4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or https://opensource.org/licenses/CDDL-1.0.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright (c) 2018, Joyent, Inc.
24 * Copyright (c) 2011, 2020, Delphix. All rights reserved.
25 * Copyright (c) 2014, Saso Kiselkov. All rights reserved.
26 * Copyright (c) 2017, Nexenta Systems, Inc. All rights reserved.
27 * Copyright (c) 2019, loli10K <ezomori.nozomu@gmail.com>. All rights reserved.
28 * Copyright (c) 2020, George Amanakis. All rights reserved.
29 * Copyright (c) 2019, Klara Inc.
30 * Copyright (c) 2019, Allan Jude
31 * Copyright (c) 2020, The FreeBSD Foundation [1]
33 * [1] Portions of this software were developed by Allan Jude
34 * under sponsorship from the FreeBSD Foundation.
38 * DVA-based Adjustable Replacement Cache
40 * While much of the theory of operation used here is
41 * based on the self-tuning, low overhead replacement cache
42 * presented by Megiddo and Modha at FAST 2003, there are some
43 * significant differences:
45 * 1. The Megiddo and Modha model assumes any page is evictable.
46 * Pages in its cache cannot be "locked" into memory. This makes
47 * the eviction algorithm simple: evict the last page in the list.
48 * This also make the performance characteristics easy to reason
49 * about. Our cache is not so simple. At any given moment, some
50 * subset of the blocks in the cache are un-evictable because we
51 * have handed out a reference to them. Blocks are only evictable
52 * when there are no external references active. This makes
53 * eviction far more problematic: we choose to evict the evictable
54 * blocks that are the "lowest" in the list.
56 * There are times when it is not possible to evict the requested
57 * space. In these circumstances we are unable to adjust the cache
58 * size. To prevent the cache growing unbounded at these times we
59 * implement a "cache throttle" that slows the flow of new data
60 * into the cache until we can make space available.
62 * 2. The Megiddo and Modha model assumes a fixed cache size.
63 * Pages are evicted when the cache is full and there is a cache
64 * miss. Our model has a variable sized cache. It grows with
65 * high use, but also tries to react to memory pressure from the
66 * operating system: decreasing its size when system memory is
69 * 3. The Megiddo and Modha model assumes a fixed page size. All
70 * elements of the cache are therefore exactly the same size. So
71 * when adjusting the cache size following a cache miss, its simply
72 * a matter of choosing a single page to evict. In our model, we
73 * have variable sized cache blocks (ranging from 512 bytes to
74 * 128K bytes). We therefore choose a set of blocks to evict to make
75 * space for a cache miss that approximates as closely as possible
76 * the space used by the new block.
78 * See also: "ARC: A Self-Tuning, Low Overhead Replacement Cache"
79 * by N. Megiddo & D. Modha, FAST 2003
85 * A new reference to a cache buffer can be obtained in two
86 * ways: 1) via a hash table lookup using the DVA as a key,
87 * or 2) via one of the ARC lists. The arc_read() interface
88 * uses method 1, while the internal ARC algorithms for
89 * adjusting the cache use method 2. We therefore provide two
90 * types of locks: 1) the hash table lock array, and 2) the
93 * Buffers do not have their own mutexes, rather they rely on the
94 * hash table mutexes for the bulk of their protection (i.e. most
95 * fields in the arc_buf_hdr_t are protected by these mutexes).
97 * buf_hash_find() returns the appropriate mutex (held) when it
98 * locates the requested buffer in the hash table. It returns
99 * NULL for the mutex if the buffer was not in the table.
101 * buf_hash_remove() expects the appropriate hash mutex to be
102 * already held before it is invoked.
104 * Each ARC state also has a mutex which is used to protect the
105 * buffer list associated with the state. When attempting to
106 * obtain a hash table lock while holding an ARC list lock you
107 * must use: mutex_tryenter() to avoid deadlock. Also note that
108 * the active state mutex must be held before the ghost state mutex.
110 * It as also possible to register a callback which is run when the
111 * metadata limit is reached and no buffers can be safely evicted. In
112 * this case the arc user should drop a reference on some arc buffers so
113 * they can be reclaimed. For example, when using the ZPL each dentry
114 * holds a references on a znode. These dentries must be pruned before
115 * the arc buffer holding the znode can be safely evicted.
117 * Note that the majority of the performance stats are manipulated
118 * with atomic operations.
120 * The L2ARC uses the l2ad_mtx on each vdev for the following:
122 * - L2ARC buflist creation
123 * - L2ARC buflist eviction
124 * - L2ARC write completion, which walks L2ARC buflists
125 * - ARC header destruction, as it removes from L2ARC buflists
126 * - ARC header release, as it removes from L2ARC buflists
132 * Every block that is in the ARC is tracked by an arc_buf_hdr_t structure.
133 * This structure can point either to a block that is still in the cache or to
134 * one that is only accessible in an L2 ARC device, or it can provide
135 * information about a block that was recently evicted. If a block is
136 * only accessible in the L2ARC, then the arc_buf_hdr_t only has enough
137 * information to retrieve it from the L2ARC device. This information is
138 * stored in the l2arc_buf_hdr_t sub-structure of the arc_buf_hdr_t. A block
139 * that is in this state cannot access the data directly.
141 * Blocks that are actively being referenced or have not been evicted
142 * are cached in the L1ARC. The L1ARC (l1arc_buf_hdr_t) is a structure within
143 * the arc_buf_hdr_t that will point to the data block in memory. A block can
144 * only be read by a consumer if it has an l1arc_buf_hdr_t. The L1ARC
145 * caches data in two ways -- in a list of ARC buffers (arc_buf_t) and
146 * also in the arc_buf_hdr_t's private physical data block pointer (b_pabd).
148 * The L1ARC's data pointer may or may not be uncompressed. The ARC has the
149 * ability to store the physical data (b_pabd) associated with the DVA of the
150 * arc_buf_hdr_t. Since the b_pabd is a copy of the on-disk physical block,
151 * it will match its on-disk compression characteristics. This behavior can be
152 * disabled by setting 'zfs_compressed_arc_enabled' to B_FALSE. When the
153 * compressed ARC functionality is disabled, the b_pabd will point to an
154 * uncompressed version of the on-disk data.
156 * Data in the L1ARC is not accessed by consumers of the ARC directly. Each
157 * arc_buf_hdr_t can have multiple ARC buffers (arc_buf_t) which reference it.
158 * Each ARC buffer (arc_buf_t) is being actively accessed by a specific ARC
159 * consumer. The ARC will provide references to this data and will keep it
160 * cached until it is no longer in use. The ARC caches only the L1ARC's physical
161 * data block and will evict any arc_buf_t that is no longer referenced. The
162 * amount of memory consumed by the arc_buf_ts' data buffers can be seen via the
163 * "overhead_size" kstat.
165 * Depending on the consumer, an arc_buf_t can be requested in uncompressed or
166 * compressed form. The typical case is that consumers will want uncompressed
167 * data, and when that happens a new data buffer is allocated where the data is
168 * decompressed for them to use. Currently the only consumer who wants
169 * compressed arc_buf_t's is "zfs send", when it streams data exactly as it
170 * exists on disk. When this happens, the arc_buf_t's data buffer is shared
171 * with the arc_buf_hdr_t.
173 * Here is a diagram showing an arc_buf_hdr_t referenced by two arc_buf_t's. The
174 * first one is owned by a compressed send consumer (and therefore references
175 * the same compressed data buffer as the arc_buf_hdr_t) and the second could be
176 * used by any other consumer (and has its own uncompressed copy of the data
191 * | b_buf +------------>+-----------+ arc_buf_t
192 * | b_pabd +-+ |b_next +---->+-----------+
193 * +-----------+ | |-----------| |b_next +-->NULL
194 * | |b_comp = T | +-----------+
195 * | |b_data +-+ |b_comp = F |
196 * | +-----------+ | |b_data +-+
197 * +->+------+ | +-----------+ |
199 * data | |<--------------+ | uncompressed
200 * +------+ compressed, | data
201 * shared +-->+------+
206 * When a consumer reads a block, the ARC must first look to see if the
207 * arc_buf_hdr_t is cached. If the hdr is cached then the ARC allocates a new
208 * arc_buf_t and either copies uncompressed data into a new data buffer from an
209 * existing uncompressed arc_buf_t, decompresses the hdr's b_pabd buffer into a
210 * new data buffer, or shares the hdr's b_pabd buffer, depending on whether the
211 * hdr is compressed and the desired compression characteristics of the
212 * arc_buf_t consumer. If the arc_buf_t ends up sharing data with the
213 * arc_buf_hdr_t and both of them are uncompressed then the arc_buf_t must be
214 * the last buffer in the hdr's b_buf list, however a shared compressed buf can
215 * be anywhere in the hdr's list.
217 * The diagram below shows an example of an uncompressed ARC hdr that is
218 * sharing its data with an arc_buf_t (note that the shared uncompressed buf is
219 * the last element in the buf list):
231 * | | arc_buf_t (shared)
232 * | b_buf +------------>+---------+ arc_buf_t
233 * | | |b_next +---->+---------+
234 * | b_pabd +-+ |---------| |b_next +-->NULL
235 * +-----------+ | | | +---------+
237 * | +---------+ | |b_data +-+
238 * +->+------+ | +---------+ |
240 * uncompressed | | | |
243 * | uncompressed | | |
246 * +---------------------------------+
248 * Writing to the ARC requires that the ARC first discard the hdr's b_pabd
249 * since the physical block is about to be rewritten. The new data contents
250 * will be contained in the arc_buf_t. As the I/O pipeline performs the write,
251 * it may compress the data before writing it to disk. The ARC will be called
252 * with the transformed data and will memcpy the transformed on-disk block into
253 * a newly allocated b_pabd. Writes are always done into buffers which have
254 * either been loaned (and hence are new and don't have other readers) or
255 * buffers which have been released (and hence have their own hdr, if there
256 * were originally other readers of the buf's original hdr). This ensures that
257 * the ARC only needs to update a single buf and its hdr after a write occurs.
259 * When the L2ARC is in use, it will also take advantage of the b_pabd. The
260 * L2ARC will always write the contents of b_pabd to the L2ARC. This means
261 * that when compressed ARC is enabled that the L2ARC blocks are identical
262 * to the on-disk block in the main data pool. This provides a significant
263 * advantage since the ARC can leverage the bp's checksum when reading from the
264 * L2ARC to determine if the contents are valid. However, if the compressed
265 * ARC is disabled, then the L2ARC's block must be transformed to look
266 * like the physical block in the main data pool before comparing the
267 * checksum and determining its validity.
269 * The L1ARC has a slightly different system for storing encrypted data.
270 * Raw (encrypted + possibly compressed) data has a few subtle differences from
271 * data that is just compressed. The biggest difference is that it is not
272 * possible to decrypt encrypted data (or vice-versa) if the keys aren't loaded.
273 * The other difference is that encryption cannot be treated as a suggestion.
274 * If a caller would prefer compressed data, but they actually wind up with
275 * uncompressed data the worst thing that could happen is there might be a
276 * performance hit. If the caller requests encrypted data, however, we must be
277 * sure they actually get it or else secret information could be leaked. Raw
278 * data is stored in hdr->b_crypt_hdr.b_rabd. An encrypted header, therefore,
279 * may have both an encrypted version and a decrypted version of its data at
280 * once. When a caller needs a raw arc_buf_t, it is allocated and the data is
281 * copied out of this header. To avoid complications with b_pabd, raw buffers
287 #include <sys/spa_impl.h>
288 #include <sys/zio_compress.h>
289 #include <sys/zio_checksum.h>
290 #include <sys/zfs_context.h>
292 #include <sys/zfs_refcount.h>
293 #include <sys/vdev.h>
294 #include <sys/vdev_impl.h>
295 #include <sys/dsl_pool.h>
296 #include <sys/multilist.h>
299 #include <sys/fm/fs/zfs.h>
300 #include <sys/callb.h>
301 #include <sys/kstat.h>
302 #include <sys/zthr.h>
303 #include <zfs_fletcher.h>
304 #include <sys/arc_impl.h>
305 #include <sys/trace_zfs.h>
306 #include <sys/aggsum.h>
307 #include <sys/wmsum.h>
308 #include <cityhash.h>
309 #include <sys/vdev_trim.h>
310 #include <sys/zfs_racct.h>
311 #include <sys/zstd/zstd.h>
314 /* set with ZFS_DEBUG=watch, to enable watchpoints on frozen buffers */
315 boolean_t arc_watch = B_FALSE;
319 * This thread's job is to keep enough free memory in the system, by
320 * calling arc_kmem_reap_soon() plus arc_reduce_target_size(), which improves
321 * arc_available_memory().
323 static zthr_t *arc_reap_zthr;
326 * This thread's job is to keep arc_size under arc_c, by calling
327 * arc_evict(), which improves arc_is_overflowing().
329 static zthr_t *arc_evict_zthr;
330 static arc_buf_hdr_t **arc_state_evict_markers;
331 static int arc_state_evict_marker_count;
333 static kmutex_t arc_evict_lock;
334 static boolean_t arc_evict_needed = B_FALSE;
335 static clock_t arc_last_uncached_flush;
338 * Count of bytes evicted since boot.
340 static uint64_t arc_evict_count;
343 * List of arc_evict_waiter_t's, representing threads waiting for the
344 * arc_evict_count to reach specific values.
346 static list_t arc_evict_waiters;
349 * When arc_is_overflowing(), arc_get_data_impl() waits for this percent of
350 * the requested amount of data to be evicted. For example, by default for
351 * every 2KB that's evicted, 1KB of it may be "reused" by a new allocation.
352 * Since this is above 100%, it ensures that progress is made towards getting
353 * arc_size under arc_c. Since this is finite, it ensures that allocations
354 * can still happen, even during the potentially long time that arc_size is
357 static uint_t zfs_arc_eviction_pct = 200;
360 * The number of headers to evict in arc_evict_state_impl() before
361 * dropping the sublist lock and evicting from another sublist. A lower
362 * value means we're more likely to evict the "correct" header (i.e. the
363 * oldest header in the arc state), but comes with higher overhead
364 * (i.e. more invocations of arc_evict_state_impl()).
366 static uint_t zfs_arc_evict_batch_limit = 10;
368 /* number of seconds before growing cache again */
369 uint_t arc_grow_retry = 5;
372 * Minimum time between calls to arc_kmem_reap_soon().
374 static const int arc_kmem_cache_reap_retry_ms = 1000;
376 /* shift of arc_c for calculating overflow limit in arc_get_data_impl */
377 static int zfs_arc_overflow_shift = 8;
379 /* log2(fraction of arc to reclaim) */
380 uint_t arc_shrink_shift = 7;
382 /* percent of pagecache to reclaim arc to */
384 uint_t zfs_arc_pc_percent = 0;
388 * log2(fraction of ARC which must be free to allow growing).
389 * I.e. If there is less than arc_c >> arc_no_grow_shift free memory,
390 * when reading a new block into the ARC, we will evict an equal-sized block
393 * This must be less than arc_shrink_shift, so that when we shrink the ARC,
394 * we will still not allow it to grow.
396 uint_t arc_no_grow_shift = 5;
400 * minimum lifespan of a prefetch block in clock ticks
401 * (initialized in arc_init())
403 static uint_t arc_min_prefetch_ms;
404 static uint_t arc_min_prescient_prefetch_ms;
407 * If this percent of memory is free, don't throttle.
409 uint_t arc_lotsfree_percent = 10;
412 * The arc has filled available memory and has now warmed up.
417 * These tunables are for performance analysis.
419 uint64_t zfs_arc_max = 0;
420 uint64_t zfs_arc_min = 0;
421 static uint64_t zfs_arc_dnode_limit = 0;
422 static uint_t zfs_arc_dnode_reduce_percent = 10;
423 static uint_t zfs_arc_grow_retry = 0;
424 static uint_t zfs_arc_shrink_shift = 0;
425 uint_t zfs_arc_average_blocksize = 8 * 1024; /* 8KB */
428 * ARC dirty data constraints for arc_tempreserve_space() throttle:
429 * * total dirty data limit
430 * * anon block dirty limit
431 * * each pool's anon allowance
433 static const unsigned long zfs_arc_dirty_limit_percent = 50;
434 static const unsigned long zfs_arc_anon_limit_percent = 25;
435 static const unsigned long zfs_arc_pool_dirty_percent = 20;
438 * Enable or disable compressed arc buffers.
440 int zfs_compressed_arc_enabled = B_TRUE;
443 * Balance between metadata and data on ghost hits. Values above 100
444 * increase metadata caching by proportionally reducing effect of ghost
445 * data hits on target data/metadata rate.
447 static uint_t zfs_arc_meta_balance = 500;
450 * Percentage that can be consumed by dnodes of ARC meta buffers.
452 static uint_t zfs_arc_dnode_limit_percent = 10;
455 * These tunables are Linux-specific
457 static uint64_t zfs_arc_sys_free = 0;
458 static uint_t zfs_arc_min_prefetch_ms = 0;
459 static uint_t zfs_arc_min_prescient_prefetch_ms = 0;
460 static uint_t zfs_arc_lotsfree_percent = 10;
463 * Number of arc_prune threads
465 static int zfs_arc_prune_task_threads = 1;
468 arc_state_t ARC_anon;
470 arc_state_t ARC_mru_ghost;
472 arc_state_t ARC_mfu_ghost;
473 arc_state_t ARC_l2c_only;
474 arc_state_t ARC_uncached;
476 arc_stats_t arc_stats = {
477 { "hits", KSTAT_DATA_UINT64 },
478 { "iohits", KSTAT_DATA_UINT64 },
479 { "misses", KSTAT_DATA_UINT64 },
480 { "demand_data_hits", KSTAT_DATA_UINT64 },
481 { "demand_data_iohits", KSTAT_DATA_UINT64 },
482 { "demand_data_misses", KSTAT_DATA_UINT64 },
483 { "demand_metadata_hits", KSTAT_DATA_UINT64 },
484 { "demand_metadata_iohits", KSTAT_DATA_UINT64 },
485 { "demand_metadata_misses", KSTAT_DATA_UINT64 },
486 { "prefetch_data_hits", KSTAT_DATA_UINT64 },
487 { "prefetch_data_iohits", KSTAT_DATA_UINT64 },
488 { "prefetch_data_misses", KSTAT_DATA_UINT64 },
489 { "prefetch_metadata_hits", KSTAT_DATA_UINT64 },
490 { "prefetch_metadata_iohits", KSTAT_DATA_UINT64 },
491 { "prefetch_metadata_misses", KSTAT_DATA_UINT64 },
492 { "mru_hits", KSTAT_DATA_UINT64 },
493 { "mru_ghost_hits", KSTAT_DATA_UINT64 },
494 { "mfu_hits", KSTAT_DATA_UINT64 },
495 { "mfu_ghost_hits", KSTAT_DATA_UINT64 },
496 { "uncached_hits", KSTAT_DATA_UINT64 },
497 { "deleted", KSTAT_DATA_UINT64 },
498 { "mutex_miss", KSTAT_DATA_UINT64 },
499 { "access_skip", KSTAT_DATA_UINT64 },
500 { "evict_skip", KSTAT_DATA_UINT64 },
501 { "evict_not_enough", KSTAT_DATA_UINT64 },
502 { "evict_l2_cached", KSTAT_DATA_UINT64 },
503 { "evict_l2_eligible", KSTAT_DATA_UINT64 },
504 { "evict_l2_eligible_mfu", KSTAT_DATA_UINT64 },
505 { "evict_l2_eligible_mru", KSTAT_DATA_UINT64 },
506 { "evict_l2_ineligible", KSTAT_DATA_UINT64 },
507 { "evict_l2_skip", KSTAT_DATA_UINT64 },
508 { "hash_elements", KSTAT_DATA_UINT64 },
509 { "hash_elements_max", KSTAT_DATA_UINT64 },
510 { "hash_collisions", KSTAT_DATA_UINT64 },
511 { "hash_chains", KSTAT_DATA_UINT64 },
512 { "hash_chain_max", KSTAT_DATA_UINT64 },
513 { "meta", KSTAT_DATA_UINT64 },
514 { "pd", KSTAT_DATA_UINT64 },
515 { "pm", KSTAT_DATA_UINT64 },
516 { "c", KSTAT_DATA_UINT64 },
517 { "c_min", KSTAT_DATA_UINT64 },
518 { "c_max", KSTAT_DATA_UINT64 },
519 { "size", KSTAT_DATA_UINT64 },
520 { "compressed_size", KSTAT_DATA_UINT64 },
521 { "uncompressed_size", KSTAT_DATA_UINT64 },
522 { "overhead_size", KSTAT_DATA_UINT64 },
523 { "hdr_size", KSTAT_DATA_UINT64 },
524 { "data_size", KSTAT_DATA_UINT64 },
525 { "metadata_size", KSTAT_DATA_UINT64 },
526 { "dbuf_size", KSTAT_DATA_UINT64 },
527 { "dnode_size", KSTAT_DATA_UINT64 },
528 { "bonus_size", KSTAT_DATA_UINT64 },
529 #if defined(COMPAT_FREEBSD11)
530 { "other_size", KSTAT_DATA_UINT64 },
532 { "anon_size", KSTAT_DATA_UINT64 },
533 { "anon_data", KSTAT_DATA_UINT64 },
534 { "anon_metadata", KSTAT_DATA_UINT64 },
535 { "anon_evictable_data", KSTAT_DATA_UINT64 },
536 { "anon_evictable_metadata", KSTAT_DATA_UINT64 },
537 { "mru_size", KSTAT_DATA_UINT64 },
538 { "mru_data", KSTAT_DATA_UINT64 },
539 { "mru_metadata", KSTAT_DATA_UINT64 },
540 { "mru_evictable_data", KSTAT_DATA_UINT64 },
541 { "mru_evictable_metadata", KSTAT_DATA_UINT64 },
542 { "mru_ghost_size", KSTAT_DATA_UINT64 },
543 { "mru_ghost_data", KSTAT_DATA_UINT64 },
544 { "mru_ghost_metadata", KSTAT_DATA_UINT64 },
545 { "mru_ghost_evictable_data", KSTAT_DATA_UINT64 },
546 { "mru_ghost_evictable_metadata", KSTAT_DATA_UINT64 },
547 { "mfu_size", KSTAT_DATA_UINT64 },
548 { "mfu_data", KSTAT_DATA_UINT64 },
549 { "mfu_metadata", KSTAT_DATA_UINT64 },
550 { "mfu_evictable_data", KSTAT_DATA_UINT64 },
551 { "mfu_evictable_metadata", KSTAT_DATA_UINT64 },
552 { "mfu_ghost_size", KSTAT_DATA_UINT64 },
553 { "mfu_ghost_data", KSTAT_DATA_UINT64 },
554 { "mfu_ghost_metadata", KSTAT_DATA_UINT64 },
555 { "mfu_ghost_evictable_data", KSTAT_DATA_UINT64 },
556 { "mfu_ghost_evictable_metadata", KSTAT_DATA_UINT64 },
557 { "uncached_size", KSTAT_DATA_UINT64 },
558 { "uncached_data", KSTAT_DATA_UINT64 },
559 { "uncached_metadata", KSTAT_DATA_UINT64 },
560 { "uncached_evictable_data", KSTAT_DATA_UINT64 },
561 { "uncached_evictable_metadata", KSTAT_DATA_UINT64 },
562 { "l2_hits", KSTAT_DATA_UINT64 },
563 { "l2_misses", KSTAT_DATA_UINT64 },
564 { "l2_prefetch_asize", KSTAT_DATA_UINT64 },
565 { "l2_mru_asize", KSTAT_DATA_UINT64 },
566 { "l2_mfu_asize", KSTAT_DATA_UINT64 },
567 { "l2_bufc_data_asize", KSTAT_DATA_UINT64 },
568 { "l2_bufc_metadata_asize", KSTAT_DATA_UINT64 },
569 { "l2_feeds", KSTAT_DATA_UINT64 },
570 { "l2_rw_clash", KSTAT_DATA_UINT64 },
571 { "l2_read_bytes", KSTAT_DATA_UINT64 },
572 { "l2_write_bytes", KSTAT_DATA_UINT64 },
573 { "l2_writes_sent", KSTAT_DATA_UINT64 },
574 { "l2_writes_done", KSTAT_DATA_UINT64 },
575 { "l2_writes_error", KSTAT_DATA_UINT64 },
576 { "l2_writes_lock_retry", KSTAT_DATA_UINT64 },
577 { "l2_evict_lock_retry", KSTAT_DATA_UINT64 },
578 { "l2_evict_reading", KSTAT_DATA_UINT64 },
579 { "l2_evict_l1cached", KSTAT_DATA_UINT64 },
580 { "l2_free_on_write", KSTAT_DATA_UINT64 },
581 { "l2_abort_lowmem", KSTAT_DATA_UINT64 },
582 { "l2_cksum_bad", KSTAT_DATA_UINT64 },
583 { "l2_io_error", KSTAT_DATA_UINT64 },
584 { "l2_size", KSTAT_DATA_UINT64 },
585 { "l2_asize", KSTAT_DATA_UINT64 },
586 { "l2_hdr_size", KSTAT_DATA_UINT64 },
587 { "l2_log_blk_writes", KSTAT_DATA_UINT64 },
588 { "l2_log_blk_avg_asize", KSTAT_DATA_UINT64 },
589 { "l2_log_blk_asize", KSTAT_DATA_UINT64 },
590 { "l2_log_blk_count", KSTAT_DATA_UINT64 },
591 { "l2_data_to_meta_ratio", KSTAT_DATA_UINT64 },
592 { "l2_rebuild_success", KSTAT_DATA_UINT64 },
593 { "l2_rebuild_unsupported", KSTAT_DATA_UINT64 },
594 { "l2_rebuild_io_errors", KSTAT_DATA_UINT64 },
595 { "l2_rebuild_dh_errors", KSTAT_DATA_UINT64 },
596 { "l2_rebuild_cksum_lb_errors", KSTAT_DATA_UINT64 },
597 { "l2_rebuild_lowmem", KSTAT_DATA_UINT64 },
598 { "l2_rebuild_size", KSTAT_DATA_UINT64 },
599 { "l2_rebuild_asize", KSTAT_DATA_UINT64 },
600 { "l2_rebuild_bufs", KSTAT_DATA_UINT64 },
601 { "l2_rebuild_bufs_precached", KSTAT_DATA_UINT64 },
602 { "l2_rebuild_log_blks", KSTAT_DATA_UINT64 },
603 { "memory_throttle_count", KSTAT_DATA_UINT64 },
604 { "memory_direct_count", KSTAT_DATA_UINT64 },
605 { "memory_indirect_count", KSTAT_DATA_UINT64 },
606 { "memory_all_bytes", KSTAT_DATA_UINT64 },
607 { "memory_free_bytes", KSTAT_DATA_UINT64 },
608 { "memory_available_bytes", KSTAT_DATA_INT64 },
609 { "arc_no_grow", KSTAT_DATA_UINT64 },
610 { "arc_tempreserve", KSTAT_DATA_UINT64 },
611 { "arc_loaned_bytes", KSTAT_DATA_UINT64 },
612 { "arc_prune", KSTAT_DATA_UINT64 },
613 { "arc_meta_used", KSTAT_DATA_UINT64 },
614 { "arc_dnode_limit", KSTAT_DATA_UINT64 },
615 { "async_upgrade_sync", KSTAT_DATA_UINT64 },
616 { "predictive_prefetch", KSTAT_DATA_UINT64 },
617 { "demand_hit_predictive_prefetch", KSTAT_DATA_UINT64 },
618 { "demand_iohit_predictive_prefetch", KSTAT_DATA_UINT64 },
619 { "prescient_prefetch", KSTAT_DATA_UINT64 },
620 { "demand_hit_prescient_prefetch", KSTAT_DATA_UINT64 },
621 { "demand_iohit_prescient_prefetch", KSTAT_DATA_UINT64 },
622 { "arc_need_free", KSTAT_DATA_UINT64 },
623 { "arc_sys_free", KSTAT_DATA_UINT64 },
624 { "arc_raw_size", KSTAT_DATA_UINT64 },
625 { "cached_only_in_progress", KSTAT_DATA_UINT64 },
626 { "abd_chunk_waste_size", KSTAT_DATA_UINT64 },
631 #define ARCSTAT_MAX(stat, val) { \
633 while ((val) > (m = arc_stats.stat.value.ui64) && \
634 (m != atomic_cas_64(&arc_stats.stat.value.ui64, m, (val)))) \
639 * We define a macro to allow ARC hits/misses to be easily broken down by
640 * two separate conditions, giving a total of four different subtypes for
641 * each of hits and misses (so eight statistics total).
643 #define ARCSTAT_CONDSTAT(cond1, stat1, notstat1, cond2, stat2, notstat2, stat) \
646 ARCSTAT_BUMP(arcstat_##stat1##_##stat2##_##stat); \
648 ARCSTAT_BUMP(arcstat_##stat1##_##notstat2##_##stat); \
652 ARCSTAT_BUMP(arcstat_##notstat1##_##stat2##_##stat); \
654 ARCSTAT_BUMP(arcstat_##notstat1##_##notstat2##_##stat);\
659 * This macro allows us to use kstats as floating averages. Each time we
660 * update this kstat, we first factor it and the update value by
661 * ARCSTAT_AVG_FACTOR to shrink the new value's contribution to the overall
662 * average. This macro assumes that integer loads and stores are atomic, but
663 * is not safe for multiple writers updating the kstat in parallel (only the
664 * last writer's update will remain).
666 #define ARCSTAT_F_AVG_FACTOR 3
667 #define ARCSTAT_F_AVG(stat, value) \
669 uint64_t x = ARCSTAT(stat); \
670 x = x - x / ARCSTAT_F_AVG_FACTOR + \
671 (value) / ARCSTAT_F_AVG_FACTOR; \
675 static kstat_t *arc_ksp;
678 * There are several ARC variables that are critical to export as kstats --
679 * but we don't want to have to grovel around in the kstat whenever we wish to
680 * manipulate them. For these variables, we therefore define them to be in
681 * terms of the statistic variable. This assures that we are not introducing
682 * the possibility of inconsistency by having shadow copies of the variables,
683 * while still allowing the code to be readable.
685 #define arc_tempreserve ARCSTAT(arcstat_tempreserve)
686 #define arc_loaned_bytes ARCSTAT(arcstat_loaned_bytes)
687 #define arc_dnode_limit ARCSTAT(arcstat_dnode_limit) /* max size for dnodes */
688 #define arc_need_free ARCSTAT(arcstat_need_free) /* waiting to be evicted */
690 hrtime_t arc_growtime;
691 list_t arc_prune_list;
692 kmutex_t arc_prune_mtx;
693 taskq_t *arc_prune_taskq;
695 #define GHOST_STATE(state) \
696 ((state) == arc_mru_ghost || (state) == arc_mfu_ghost || \
697 (state) == arc_l2c_only)
699 #define HDR_IN_HASH_TABLE(hdr) ((hdr)->b_flags & ARC_FLAG_IN_HASH_TABLE)
700 #define HDR_IO_IN_PROGRESS(hdr) ((hdr)->b_flags & ARC_FLAG_IO_IN_PROGRESS)
701 #define HDR_IO_ERROR(hdr) ((hdr)->b_flags & ARC_FLAG_IO_ERROR)
702 #define HDR_PREFETCH(hdr) ((hdr)->b_flags & ARC_FLAG_PREFETCH)
703 #define HDR_PRESCIENT_PREFETCH(hdr) \
704 ((hdr)->b_flags & ARC_FLAG_PRESCIENT_PREFETCH)
705 #define HDR_COMPRESSION_ENABLED(hdr) \
706 ((hdr)->b_flags & ARC_FLAG_COMPRESSED_ARC)
708 #define HDR_L2CACHE(hdr) ((hdr)->b_flags & ARC_FLAG_L2CACHE)
709 #define HDR_UNCACHED(hdr) ((hdr)->b_flags & ARC_FLAG_UNCACHED)
710 #define HDR_L2_READING(hdr) \
711 (((hdr)->b_flags & ARC_FLAG_IO_IN_PROGRESS) && \
712 ((hdr)->b_flags & ARC_FLAG_HAS_L2HDR))
713 #define HDR_L2_WRITING(hdr) ((hdr)->b_flags & ARC_FLAG_L2_WRITING)
714 #define HDR_L2_EVICTED(hdr) ((hdr)->b_flags & ARC_FLAG_L2_EVICTED)
715 #define HDR_L2_WRITE_HEAD(hdr) ((hdr)->b_flags & ARC_FLAG_L2_WRITE_HEAD)
716 #define HDR_PROTECTED(hdr) ((hdr)->b_flags & ARC_FLAG_PROTECTED)
717 #define HDR_NOAUTH(hdr) ((hdr)->b_flags & ARC_FLAG_NOAUTH)
718 #define HDR_SHARED_DATA(hdr) ((hdr)->b_flags & ARC_FLAG_SHARED_DATA)
720 #define HDR_ISTYPE_METADATA(hdr) \
721 ((hdr)->b_flags & ARC_FLAG_BUFC_METADATA)
722 #define HDR_ISTYPE_DATA(hdr) (!HDR_ISTYPE_METADATA(hdr))
724 #define HDR_HAS_L1HDR(hdr) ((hdr)->b_flags & ARC_FLAG_HAS_L1HDR)
725 #define HDR_HAS_L2HDR(hdr) ((hdr)->b_flags & ARC_FLAG_HAS_L2HDR)
726 #define HDR_HAS_RABD(hdr) \
727 (HDR_HAS_L1HDR(hdr) && HDR_PROTECTED(hdr) && \
728 (hdr)->b_crypt_hdr.b_rabd != NULL)
729 #define HDR_ENCRYPTED(hdr) \
730 (HDR_PROTECTED(hdr) && DMU_OT_IS_ENCRYPTED((hdr)->b_crypt_hdr.b_ot))
731 #define HDR_AUTHENTICATED(hdr) \
732 (HDR_PROTECTED(hdr) && !DMU_OT_IS_ENCRYPTED((hdr)->b_crypt_hdr.b_ot))
734 /* For storing compression mode in b_flags */
735 #define HDR_COMPRESS_OFFSET (highbit64(ARC_FLAG_COMPRESS_0) - 1)
737 #define HDR_GET_COMPRESS(hdr) ((enum zio_compress)BF32_GET((hdr)->b_flags, \
738 HDR_COMPRESS_OFFSET, SPA_COMPRESSBITS))
739 #define HDR_SET_COMPRESS(hdr, cmp) BF32_SET((hdr)->b_flags, \
740 HDR_COMPRESS_OFFSET, SPA_COMPRESSBITS, (cmp));
742 #define ARC_BUF_LAST(buf) ((buf)->b_next == NULL)
743 #define ARC_BUF_SHARED(buf) ((buf)->b_flags & ARC_BUF_FLAG_SHARED)
744 #define ARC_BUF_COMPRESSED(buf) ((buf)->b_flags & ARC_BUF_FLAG_COMPRESSED)
745 #define ARC_BUF_ENCRYPTED(buf) ((buf)->b_flags & ARC_BUF_FLAG_ENCRYPTED)
751 #define HDR_FULL_SIZE ((int64_t)sizeof (arc_buf_hdr_t))
752 #define HDR_L2ONLY_SIZE ((int64_t)offsetof(arc_buf_hdr_t, b_l1hdr))
755 * Hash table routines
758 #define BUF_LOCKS 2048
759 typedef struct buf_hash_table {
761 arc_buf_hdr_t **ht_table;
762 kmutex_t ht_locks[BUF_LOCKS] ____cacheline_aligned;
765 static buf_hash_table_t buf_hash_table;
767 #define BUF_HASH_INDEX(spa, dva, birth) \
768 (buf_hash(spa, dva, birth) & buf_hash_table.ht_mask)
769 #define BUF_HASH_LOCK(idx) (&buf_hash_table.ht_locks[idx & (BUF_LOCKS-1)])
770 #define HDR_LOCK(hdr) \
771 (BUF_HASH_LOCK(BUF_HASH_INDEX(hdr->b_spa, &hdr->b_dva, hdr->b_birth)))
773 uint64_t zfs_crc64_table[256];
779 #define L2ARC_WRITE_SIZE (8 * 1024 * 1024) /* initial write max */
780 #define L2ARC_HEADROOM 2 /* num of writes */
783 * If we discover during ARC scan any buffers to be compressed, we boost
784 * our headroom for the next scanning cycle by this percentage multiple.
786 #define L2ARC_HEADROOM_BOOST 200
787 #define L2ARC_FEED_SECS 1 /* caching interval secs */
788 #define L2ARC_FEED_MIN_MS 200 /* min caching interval ms */
791 * We can feed L2ARC from two states of ARC buffers, mru and mfu,
792 * and each of the state has two types: data and metadata.
794 #define L2ARC_FEED_TYPES 4
796 /* L2ARC Performance Tunables */
797 uint64_t l2arc_write_max = L2ARC_WRITE_SIZE; /* def max write size */
798 uint64_t l2arc_write_boost = L2ARC_WRITE_SIZE; /* extra warmup write */
799 uint64_t l2arc_headroom = L2ARC_HEADROOM; /* # of dev writes */
800 uint64_t l2arc_headroom_boost = L2ARC_HEADROOM_BOOST;
801 uint64_t l2arc_feed_secs = L2ARC_FEED_SECS; /* interval seconds */
802 uint64_t l2arc_feed_min_ms = L2ARC_FEED_MIN_MS; /* min interval msecs */
803 int l2arc_noprefetch = B_TRUE; /* don't cache prefetch bufs */
804 int l2arc_feed_again = B_TRUE; /* turbo warmup */
805 int l2arc_norw = B_FALSE; /* no reads during writes */
806 static uint_t l2arc_meta_percent = 33; /* limit on headers size */
811 static list_t L2ARC_dev_list; /* device list */
812 static list_t *l2arc_dev_list; /* device list pointer */
813 static kmutex_t l2arc_dev_mtx; /* device list mutex */
814 static l2arc_dev_t *l2arc_dev_last; /* last device used */
815 static list_t L2ARC_free_on_write; /* free after write buf list */
816 static list_t *l2arc_free_on_write; /* free after write list ptr */
817 static kmutex_t l2arc_free_on_write_mtx; /* mutex for list */
818 static uint64_t l2arc_ndev; /* number of devices */
820 typedef struct l2arc_read_callback {
821 arc_buf_hdr_t *l2rcb_hdr; /* read header */
822 blkptr_t l2rcb_bp; /* original blkptr */
823 zbookmark_phys_t l2rcb_zb; /* original bookmark */
824 int l2rcb_flags; /* original flags */
825 abd_t *l2rcb_abd; /* temporary buffer */
826 } l2arc_read_callback_t;
828 typedef struct l2arc_data_free {
829 /* protected by l2arc_free_on_write_mtx */
832 arc_buf_contents_t l2df_type;
833 list_node_t l2df_list_node;
836 typedef enum arc_fill_flags {
837 ARC_FILL_LOCKED = 1 << 0, /* hdr lock is held */
838 ARC_FILL_COMPRESSED = 1 << 1, /* fill with compressed data */
839 ARC_FILL_ENCRYPTED = 1 << 2, /* fill with encrypted data */
840 ARC_FILL_NOAUTH = 1 << 3, /* don't attempt to authenticate */
841 ARC_FILL_IN_PLACE = 1 << 4 /* fill in place (special case) */
844 typedef enum arc_ovf_level {
845 ARC_OVF_NONE, /* ARC within target size. */
846 ARC_OVF_SOME, /* ARC is slightly overflowed. */
847 ARC_OVF_SEVERE /* ARC is severely overflowed. */
850 static kmutex_t l2arc_feed_thr_lock;
851 static kcondvar_t l2arc_feed_thr_cv;
852 static uint8_t l2arc_thread_exit;
854 static kmutex_t l2arc_rebuild_thr_lock;
855 static kcondvar_t l2arc_rebuild_thr_cv;
857 enum arc_hdr_alloc_flags {
858 ARC_HDR_ALLOC_RDATA = 0x1,
859 ARC_HDR_USE_RESERVE = 0x4,
860 ARC_HDR_ALLOC_LINEAR = 0x8,
864 static abd_t *arc_get_data_abd(arc_buf_hdr_t *, uint64_t, const void *, int);
865 static void *arc_get_data_buf(arc_buf_hdr_t *, uint64_t, const void *);
866 static void arc_get_data_impl(arc_buf_hdr_t *, uint64_t, const void *, int);
867 static void arc_free_data_abd(arc_buf_hdr_t *, abd_t *, uint64_t, const void *);
868 static void arc_free_data_buf(arc_buf_hdr_t *, void *, uint64_t, const void *);
869 static void arc_free_data_impl(arc_buf_hdr_t *hdr, uint64_t size,
871 static void arc_hdr_free_abd(arc_buf_hdr_t *, boolean_t);
872 static void arc_hdr_alloc_abd(arc_buf_hdr_t *, int);
873 static void arc_hdr_destroy(arc_buf_hdr_t *);
874 static void arc_access(arc_buf_hdr_t *, arc_flags_t, boolean_t);
875 static void arc_buf_watch(arc_buf_t *);
876 static void arc_change_state(arc_state_t *, arc_buf_hdr_t *);
878 static arc_buf_contents_t arc_buf_type(arc_buf_hdr_t *);
879 static uint32_t arc_bufc_to_flags(arc_buf_contents_t);
880 static inline void arc_hdr_set_flags(arc_buf_hdr_t *hdr, arc_flags_t flags);
881 static inline void arc_hdr_clear_flags(arc_buf_hdr_t *hdr, arc_flags_t flags);
883 static boolean_t l2arc_write_eligible(uint64_t, arc_buf_hdr_t *);
884 static void l2arc_read_done(zio_t *);
885 static void l2arc_do_free_on_write(void);
886 static void l2arc_hdr_arcstats_update(arc_buf_hdr_t *hdr, boolean_t incr,
887 boolean_t state_only);
889 #define l2arc_hdr_arcstats_increment(hdr) \
890 l2arc_hdr_arcstats_update((hdr), B_TRUE, B_FALSE)
891 #define l2arc_hdr_arcstats_decrement(hdr) \
892 l2arc_hdr_arcstats_update((hdr), B_FALSE, B_FALSE)
893 #define l2arc_hdr_arcstats_increment_state(hdr) \
894 l2arc_hdr_arcstats_update((hdr), B_TRUE, B_TRUE)
895 #define l2arc_hdr_arcstats_decrement_state(hdr) \
896 l2arc_hdr_arcstats_update((hdr), B_FALSE, B_TRUE)
899 * l2arc_exclude_special : A zfs module parameter that controls whether buffers
900 * present on special vdevs are eligibile for caching in L2ARC. If
901 * set to 1, exclude dbufs on special vdevs from being cached to
904 int l2arc_exclude_special = 0;
907 * l2arc_mfuonly : A ZFS module parameter that controls whether only MFU
908 * metadata and data are cached from ARC into L2ARC.
910 static int l2arc_mfuonly = 0;
914 * l2arc_trim_ahead : A ZFS module parameter that controls how much ahead of
915 * the current write size (l2arc_write_max) we should TRIM if we
916 * have filled the device. It is defined as a percentage of the
917 * write size. If set to 100 we trim twice the space required to
918 * accommodate upcoming writes. A minimum of 64MB will be trimmed.
919 * It also enables TRIM of the whole L2ARC device upon creation or
920 * addition to an existing pool or if the header of the device is
921 * invalid upon importing a pool or onlining a cache device. The
922 * default is 0, which disables TRIM on L2ARC altogether as it can
923 * put significant stress on the underlying storage devices. This
924 * will vary depending of how well the specific device handles
927 static uint64_t l2arc_trim_ahead = 0;
930 * Performance tuning of L2ARC persistence:
932 * l2arc_rebuild_enabled : A ZFS module parameter that controls whether adding
933 * an L2ARC device (either at pool import or later) will attempt
934 * to rebuild L2ARC buffer contents.
935 * l2arc_rebuild_blocks_min_l2size : A ZFS module parameter that controls
936 * whether log blocks are written to the L2ARC device. If the L2ARC
937 * device is less than 1GB, the amount of data l2arc_evict()
938 * evicts is significant compared to the amount of restored L2ARC
939 * data. In this case do not write log blocks in L2ARC in order
940 * not to waste space.
942 static int l2arc_rebuild_enabled = B_TRUE;
943 static uint64_t l2arc_rebuild_blocks_min_l2size = 1024 * 1024 * 1024;
945 /* L2ARC persistence rebuild control routines. */
946 void l2arc_rebuild_vdev(vdev_t *vd, boolean_t reopen);
947 static __attribute__((noreturn)) void l2arc_dev_rebuild_thread(void *arg);
948 static int l2arc_rebuild(l2arc_dev_t *dev);
950 /* L2ARC persistence read I/O routines. */
951 static int l2arc_dev_hdr_read(l2arc_dev_t *dev);
952 static int l2arc_log_blk_read(l2arc_dev_t *dev,
953 const l2arc_log_blkptr_t *this_lp, const l2arc_log_blkptr_t *next_lp,
954 l2arc_log_blk_phys_t *this_lb, l2arc_log_blk_phys_t *next_lb,
955 zio_t *this_io, zio_t **next_io);
956 static zio_t *l2arc_log_blk_fetch(vdev_t *vd,
957 const l2arc_log_blkptr_t *lp, l2arc_log_blk_phys_t *lb);
958 static void l2arc_log_blk_fetch_abort(zio_t *zio);
960 /* L2ARC persistence block restoration routines. */
961 static void l2arc_log_blk_restore(l2arc_dev_t *dev,
962 const l2arc_log_blk_phys_t *lb, uint64_t lb_asize);
963 static void l2arc_hdr_restore(const l2arc_log_ent_phys_t *le,
966 /* L2ARC persistence write I/O routines. */
967 static uint64_t l2arc_log_blk_commit(l2arc_dev_t *dev, zio_t *pio,
968 l2arc_write_callback_t *cb);
970 /* L2ARC persistence auxiliary routines. */
971 boolean_t l2arc_log_blkptr_valid(l2arc_dev_t *dev,
972 const l2arc_log_blkptr_t *lbp);
973 static boolean_t l2arc_log_blk_insert(l2arc_dev_t *dev,
974 const arc_buf_hdr_t *ab);
975 boolean_t l2arc_range_check_overlap(uint64_t bottom,
976 uint64_t top, uint64_t check);
977 static void l2arc_blk_fetch_done(zio_t *zio);
978 static inline uint64_t
979 l2arc_log_blk_overhead(uint64_t write_sz, l2arc_dev_t *dev);
982 * We use Cityhash for this. It's fast, and has good hash properties without
983 * requiring any large static buffers.
986 buf_hash(uint64_t spa, const dva_t *dva, uint64_t birth)
988 return (cityhash4(spa, dva->dva_word[0], dva->dva_word[1], birth));
991 #define HDR_EMPTY(hdr) \
992 ((hdr)->b_dva.dva_word[0] == 0 && \
993 (hdr)->b_dva.dva_word[1] == 0)
995 #define HDR_EMPTY_OR_LOCKED(hdr) \
996 (HDR_EMPTY(hdr) || MUTEX_HELD(HDR_LOCK(hdr)))
998 #define HDR_EQUAL(spa, dva, birth, hdr) \
999 ((hdr)->b_dva.dva_word[0] == (dva)->dva_word[0]) && \
1000 ((hdr)->b_dva.dva_word[1] == (dva)->dva_word[1]) && \
1001 ((hdr)->b_birth == birth) && ((hdr)->b_spa == spa)
1004 buf_discard_identity(arc_buf_hdr_t *hdr)
1006 hdr->b_dva.dva_word[0] = 0;
1007 hdr->b_dva.dva_word[1] = 0;
1011 static arc_buf_hdr_t *
1012 buf_hash_find(uint64_t spa, const blkptr_t *bp, kmutex_t **lockp)
1014 const dva_t *dva = BP_IDENTITY(bp);
1015 uint64_t birth = BP_PHYSICAL_BIRTH(bp);
1016 uint64_t idx = BUF_HASH_INDEX(spa, dva, birth);
1017 kmutex_t *hash_lock = BUF_HASH_LOCK(idx);
1020 mutex_enter(hash_lock);
1021 for (hdr = buf_hash_table.ht_table[idx]; hdr != NULL;
1022 hdr = hdr->b_hash_next) {
1023 if (HDR_EQUAL(spa, dva, birth, hdr)) {
1028 mutex_exit(hash_lock);
1034 * Insert an entry into the hash table. If there is already an element
1035 * equal to elem in the hash table, then the already existing element
1036 * will be returned and the new element will not be inserted.
1037 * Otherwise returns NULL.
1038 * If lockp == NULL, the caller is assumed to already hold the hash lock.
1040 static arc_buf_hdr_t *
1041 buf_hash_insert(arc_buf_hdr_t *hdr, kmutex_t **lockp)
1043 uint64_t idx = BUF_HASH_INDEX(hdr->b_spa, &hdr->b_dva, hdr->b_birth);
1044 kmutex_t *hash_lock = BUF_HASH_LOCK(idx);
1045 arc_buf_hdr_t *fhdr;
1048 ASSERT(!DVA_IS_EMPTY(&hdr->b_dva));
1049 ASSERT(hdr->b_birth != 0);
1050 ASSERT(!HDR_IN_HASH_TABLE(hdr));
1052 if (lockp != NULL) {
1054 mutex_enter(hash_lock);
1056 ASSERT(MUTEX_HELD(hash_lock));
1059 for (fhdr = buf_hash_table.ht_table[idx], i = 0; fhdr != NULL;
1060 fhdr = fhdr->b_hash_next, i++) {
1061 if (HDR_EQUAL(hdr->b_spa, &hdr->b_dva, hdr->b_birth, fhdr))
1065 hdr->b_hash_next = buf_hash_table.ht_table[idx];
1066 buf_hash_table.ht_table[idx] = hdr;
1067 arc_hdr_set_flags(hdr, ARC_FLAG_IN_HASH_TABLE);
1069 /* collect some hash table performance data */
1071 ARCSTAT_BUMP(arcstat_hash_collisions);
1073 ARCSTAT_BUMP(arcstat_hash_chains);
1075 ARCSTAT_MAX(arcstat_hash_chain_max, i);
1077 uint64_t he = atomic_inc_64_nv(
1078 &arc_stats.arcstat_hash_elements.value.ui64);
1079 ARCSTAT_MAX(arcstat_hash_elements_max, he);
1085 buf_hash_remove(arc_buf_hdr_t *hdr)
1087 arc_buf_hdr_t *fhdr, **hdrp;
1088 uint64_t idx = BUF_HASH_INDEX(hdr->b_spa, &hdr->b_dva, hdr->b_birth);
1090 ASSERT(MUTEX_HELD(BUF_HASH_LOCK(idx)));
1091 ASSERT(HDR_IN_HASH_TABLE(hdr));
1093 hdrp = &buf_hash_table.ht_table[idx];
1094 while ((fhdr = *hdrp) != hdr) {
1095 ASSERT3P(fhdr, !=, NULL);
1096 hdrp = &fhdr->b_hash_next;
1098 *hdrp = hdr->b_hash_next;
1099 hdr->b_hash_next = NULL;
1100 arc_hdr_clear_flags(hdr, ARC_FLAG_IN_HASH_TABLE);
1102 /* collect some hash table performance data */
1103 atomic_dec_64(&arc_stats.arcstat_hash_elements.value.ui64);
1105 if (buf_hash_table.ht_table[idx] &&
1106 buf_hash_table.ht_table[idx]->b_hash_next == NULL)
1107 ARCSTAT_BUMPDOWN(arcstat_hash_chains);
1111 * Global data structures and functions for the buf kmem cache.
1114 static kmem_cache_t *hdr_full_cache;
1115 static kmem_cache_t *hdr_l2only_cache;
1116 static kmem_cache_t *buf_cache;
1121 #if defined(_KERNEL)
1123 * Large allocations which do not require contiguous pages
1124 * should be using vmem_free() in the linux kernel\
1126 vmem_free(buf_hash_table.ht_table,
1127 (buf_hash_table.ht_mask + 1) * sizeof (void *));
1129 kmem_free(buf_hash_table.ht_table,
1130 (buf_hash_table.ht_mask + 1) * sizeof (void *));
1132 for (int i = 0; i < BUF_LOCKS; i++)
1133 mutex_destroy(BUF_HASH_LOCK(i));
1134 kmem_cache_destroy(hdr_full_cache);
1135 kmem_cache_destroy(hdr_l2only_cache);
1136 kmem_cache_destroy(buf_cache);
1140 * Constructor callback - called when the cache is empty
1141 * and a new buf is requested.
1144 hdr_full_cons(void *vbuf, void *unused, int kmflag)
1146 (void) unused, (void) kmflag;
1147 arc_buf_hdr_t *hdr = vbuf;
1149 memset(hdr, 0, HDR_FULL_SIZE);
1150 hdr->b_l1hdr.b_byteswap = DMU_BSWAP_NUMFUNCS;
1151 zfs_refcount_create(&hdr->b_l1hdr.b_refcnt);
1153 mutex_init(&hdr->b_l1hdr.b_freeze_lock, NULL, MUTEX_DEFAULT, NULL);
1155 multilist_link_init(&hdr->b_l1hdr.b_arc_node);
1156 list_link_init(&hdr->b_l2hdr.b_l2node);
1157 arc_space_consume(HDR_FULL_SIZE, ARC_SPACE_HDRS);
1163 hdr_l2only_cons(void *vbuf, void *unused, int kmflag)
1165 (void) unused, (void) kmflag;
1166 arc_buf_hdr_t *hdr = vbuf;
1168 memset(hdr, 0, HDR_L2ONLY_SIZE);
1169 arc_space_consume(HDR_L2ONLY_SIZE, ARC_SPACE_L2HDRS);
1175 buf_cons(void *vbuf, void *unused, int kmflag)
1177 (void) unused, (void) kmflag;
1178 arc_buf_t *buf = vbuf;
1180 memset(buf, 0, sizeof (arc_buf_t));
1181 arc_space_consume(sizeof (arc_buf_t), ARC_SPACE_HDRS);
1187 * Destructor callback - called when a cached buf is
1188 * no longer required.
1191 hdr_full_dest(void *vbuf, void *unused)
1194 arc_buf_hdr_t *hdr = vbuf;
1196 ASSERT(HDR_EMPTY(hdr));
1197 zfs_refcount_destroy(&hdr->b_l1hdr.b_refcnt);
1199 mutex_destroy(&hdr->b_l1hdr.b_freeze_lock);
1201 ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node));
1202 arc_space_return(HDR_FULL_SIZE, ARC_SPACE_HDRS);
1206 hdr_l2only_dest(void *vbuf, void *unused)
1209 arc_buf_hdr_t *hdr = vbuf;
1211 ASSERT(HDR_EMPTY(hdr));
1212 arc_space_return(HDR_L2ONLY_SIZE, ARC_SPACE_L2HDRS);
1216 buf_dest(void *vbuf, void *unused)
1221 arc_space_return(sizeof (arc_buf_t), ARC_SPACE_HDRS);
1227 uint64_t *ct = NULL;
1228 uint64_t hsize = 1ULL << 12;
1232 * The hash table is big enough to fill all of physical memory
1233 * with an average block size of zfs_arc_average_blocksize (default 8K).
1234 * By default, the table will take up
1235 * totalmem * sizeof(void*) / 8K (1MB per GB with 8-byte pointers).
1237 while (hsize * zfs_arc_average_blocksize < arc_all_memory())
1240 buf_hash_table.ht_mask = hsize - 1;
1241 #if defined(_KERNEL)
1243 * Large allocations which do not require contiguous pages
1244 * should be using vmem_alloc() in the linux kernel
1246 buf_hash_table.ht_table =
1247 vmem_zalloc(hsize * sizeof (void*), KM_SLEEP);
1249 buf_hash_table.ht_table =
1250 kmem_zalloc(hsize * sizeof (void*), KM_NOSLEEP);
1252 if (buf_hash_table.ht_table == NULL) {
1253 ASSERT(hsize > (1ULL << 8));
1258 hdr_full_cache = kmem_cache_create("arc_buf_hdr_t_full", HDR_FULL_SIZE,
1259 0, hdr_full_cons, hdr_full_dest, NULL, NULL, NULL, 0);
1260 hdr_l2only_cache = kmem_cache_create("arc_buf_hdr_t_l2only",
1261 HDR_L2ONLY_SIZE, 0, hdr_l2only_cons, hdr_l2only_dest, NULL,
1263 buf_cache = kmem_cache_create("arc_buf_t", sizeof (arc_buf_t),
1264 0, buf_cons, buf_dest, NULL, NULL, NULL, 0);
1266 for (i = 0; i < 256; i++)
1267 for (ct = zfs_crc64_table + i, *ct = i, j = 8; j > 0; j--)
1268 *ct = (*ct >> 1) ^ (-(*ct & 1) & ZFS_CRC64_POLY);
1270 for (i = 0; i < BUF_LOCKS; i++)
1271 mutex_init(BUF_HASH_LOCK(i), NULL, MUTEX_DEFAULT, NULL);
1274 #define ARC_MINTIME (hz>>4) /* 62 ms */
1277 * This is the size that the buf occupies in memory. If the buf is compressed,
1278 * it will correspond to the compressed size. You should use this method of
1279 * getting the buf size unless you explicitly need the logical size.
1282 arc_buf_size(arc_buf_t *buf)
1284 return (ARC_BUF_COMPRESSED(buf) ?
1285 HDR_GET_PSIZE(buf->b_hdr) : HDR_GET_LSIZE(buf->b_hdr));
1289 arc_buf_lsize(arc_buf_t *buf)
1291 return (HDR_GET_LSIZE(buf->b_hdr));
1295 * This function will return B_TRUE if the buffer is encrypted in memory.
1296 * This buffer can be decrypted by calling arc_untransform().
1299 arc_is_encrypted(arc_buf_t *buf)
1301 return (ARC_BUF_ENCRYPTED(buf) != 0);
1305 * Returns B_TRUE if the buffer represents data that has not had its MAC
1309 arc_is_unauthenticated(arc_buf_t *buf)
1311 return (HDR_NOAUTH(buf->b_hdr) != 0);
1315 arc_get_raw_params(arc_buf_t *buf, boolean_t *byteorder, uint8_t *salt,
1316 uint8_t *iv, uint8_t *mac)
1318 arc_buf_hdr_t *hdr = buf->b_hdr;
1320 ASSERT(HDR_PROTECTED(hdr));
1322 memcpy(salt, hdr->b_crypt_hdr.b_salt, ZIO_DATA_SALT_LEN);
1323 memcpy(iv, hdr->b_crypt_hdr.b_iv, ZIO_DATA_IV_LEN);
1324 memcpy(mac, hdr->b_crypt_hdr.b_mac, ZIO_DATA_MAC_LEN);
1325 *byteorder = (hdr->b_l1hdr.b_byteswap == DMU_BSWAP_NUMFUNCS) ?
1326 ZFS_HOST_BYTEORDER : !ZFS_HOST_BYTEORDER;
1330 * Indicates how this buffer is compressed in memory. If it is not compressed
1331 * the value will be ZIO_COMPRESS_OFF. It can be made normally readable with
1332 * arc_untransform() as long as it is also unencrypted.
1335 arc_get_compression(arc_buf_t *buf)
1337 return (ARC_BUF_COMPRESSED(buf) ?
1338 HDR_GET_COMPRESS(buf->b_hdr) : ZIO_COMPRESS_OFF);
1342 * Return the compression algorithm used to store this data in the ARC. If ARC
1343 * compression is enabled or this is an encrypted block, this will be the same
1344 * as what's used to store it on-disk. Otherwise, this will be ZIO_COMPRESS_OFF.
1346 static inline enum zio_compress
1347 arc_hdr_get_compress(arc_buf_hdr_t *hdr)
1349 return (HDR_COMPRESSION_ENABLED(hdr) ?
1350 HDR_GET_COMPRESS(hdr) : ZIO_COMPRESS_OFF);
1354 arc_get_complevel(arc_buf_t *buf)
1356 return (buf->b_hdr->b_complevel);
1359 static inline boolean_t
1360 arc_buf_is_shared(arc_buf_t *buf)
1362 boolean_t shared = (buf->b_data != NULL &&
1363 buf->b_hdr->b_l1hdr.b_pabd != NULL &&
1364 abd_is_linear(buf->b_hdr->b_l1hdr.b_pabd) &&
1365 buf->b_data == abd_to_buf(buf->b_hdr->b_l1hdr.b_pabd));
1366 IMPLY(shared, HDR_SHARED_DATA(buf->b_hdr));
1367 IMPLY(shared, ARC_BUF_SHARED(buf));
1368 IMPLY(shared, ARC_BUF_COMPRESSED(buf) || ARC_BUF_LAST(buf));
1371 * It would be nice to assert arc_can_share() too, but the "hdr isn't
1372 * already being shared" requirement prevents us from doing that.
1379 * Free the checksum associated with this header. If there is no checksum, this
1383 arc_cksum_free(arc_buf_hdr_t *hdr)
1386 ASSERT(HDR_HAS_L1HDR(hdr));
1388 mutex_enter(&hdr->b_l1hdr.b_freeze_lock);
1389 if (hdr->b_l1hdr.b_freeze_cksum != NULL) {
1390 kmem_free(hdr->b_l1hdr.b_freeze_cksum, sizeof (zio_cksum_t));
1391 hdr->b_l1hdr.b_freeze_cksum = NULL;
1393 mutex_exit(&hdr->b_l1hdr.b_freeze_lock);
1398 * Return true iff at least one of the bufs on hdr is not compressed.
1399 * Encrypted buffers count as compressed.
1402 arc_hdr_has_uncompressed_buf(arc_buf_hdr_t *hdr)
1404 ASSERT(hdr->b_l1hdr.b_state == arc_anon || HDR_EMPTY_OR_LOCKED(hdr));
1406 for (arc_buf_t *b = hdr->b_l1hdr.b_buf; b != NULL; b = b->b_next) {
1407 if (!ARC_BUF_COMPRESSED(b)) {
1416 * If we've turned on the ZFS_DEBUG_MODIFY flag, verify that the buf's data
1417 * matches the checksum that is stored in the hdr. If there is no checksum,
1418 * or if the buf is compressed, this is a no-op.
1421 arc_cksum_verify(arc_buf_t *buf)
1424 arc_buf_hdr_t *hdr = buf->b_hdr;
1427 if (!(zfs_flags & ZFS_DEBUG_MODIFY))
1430 if (ARC_BUF_COMPRESSED(buf))
1433 ASSERT(HDR_HAS_L1HDR(hdr));
1435 mutex_enter(&hdr->b_l1hdr.b_freeze_lock);
1437 if (hdr->b_l1hdr.b_freeze_cksum == NULL || HDR_IO_ERROR(hdr)) {
1438 mutex_exit(&hdr->b_l1hdr.b_freeze_lock);
1442 fletcher_2_native(buf->b_data, arc_buf_size(buf), NULL, &zc);
1443 if (!ZIO_CHECKSUM_EQUAL(*hdr->b_l1hdr.b_freeze_cksum, zc))
1444 panic("buffer modified while frozen!");
1445 mutex_exit(&hdr->b_l1hdr.b_freeze_lock);
1450 * This function makes the assumption that data stored in the L2ARC
1451 * will be transformed exactly as it is in the main pool. Because of
1452 * this we can verify the checksum against the reading process's bp.
1455 arc_cksum_is_equal(arc_buf_hdr_t *hdr, zio_t *zio)
1457 ASSERT(!BP_IS_EMBEDDED(zio->io_bp));
1458 VERIFY3U(BP_GET_PSIZE(zio->io_bp), ==, HDR_GET_PSIZE(hdr));
1461 * Block pointers always store the checksum for the logical data.
1462 * If the block pointer has the gang bit set, then the checksum
1463 * it represents is for the reconstituted data and not for an
1464 * individual gang member. The zio pipeline, however, must be able to
1465 * determine the checksum of each of the gang constituents so it
1466 * treats the checksum comparison differently than what we need
1467 * for l2arc blocks. This prevents us from using the
1468 * zio_checksum_error() interface directly. Instead we must call the
1469 * zio_checksum_error_impl() so that we can ensure the checksum is
1470 * generated using the correct checksum algorithm and accounts for the
1471 * logical I/O size and not just a gang fragment.
1473 return (zio_checksum_error_impl(zio->io_spa, zio->io_bp,
1474 BP_GET_CHECKSUM(zio->io_bp), zio->io_abd, zio->io_size,
1475 zio->io_offset, NULL) == 0);
1479 * Given a buf full of data, if ZFS_DEBUG_MODIFY is enabled this computes a
1480 * checksum and attaches it to the buf's hdr so that we can ensure that the buf
1481 * isn't modified later on. If buf is compressed or there is already a checksum
1482 * on the hdr, this is a no-op (we only checksum uncompressed bufs).
1485 arc_cksum_compute(arc_buf_t *buf)
1487 if (!(zfs_flags & ZFS_DEBUG_MODIFY))
1491 arc_buf_hdr_t *hdr = buf->b_hdr;
1492 ASSERT(HDR_HAS_L1HDR(hdr));
1493 mutex_enter(&hdr->b_l1hdr.b_freeze_lock);
1494 if (hdr->b_l1hdr.b_freeze_cksum != NULL || ARC_BUF_COMPRESSED(buf)) {
1495 mutex_exit(&hdr->b_l1hdr.b_freeze_lock);
1499 ASSERT(!ARC_BUF_ENCRYPTED(buf));
1500 ASSERT(!ARC_BUF_COMPRESSED(buf));
1501 hdr->b_l1hdr.b_freeze_cksum = kmem_alloc(sizeof (zio_cksum_t),
1503 fletcher_2_native(buf->b_data, arc_buf_size(buf), NULL,
1504 hdr->b_l1hdr.b_freeze_cksum);
1505 mutex_exit(&hdr->b_l1hdr.b_freeze_lock);
1512 arc_buf_sigsegv(int sig, siginfo_t *si, void *unused)
1514 (void) sig, (void) unused;
1515 panic("Got SIGSEGV at address: 0x%lx\n", (long)si->si_addr);
1520 arc_buf_unwatch(arc_buf_t *buf)
1524 ASSERT0(mprotect(buf->b_data, arc_buf_size(buf),
1525 PROT_READ | PROT_WRITE));
1533 arc_buf_watch(arc_buf_t *buf)
1537 ASSERT0(mprotect(buf->b_data, arc_buf_size(buf),
1544 static arc_buf_contents_t
1545 arc_buf_type(arc_buf_hdr_t *hdr)
1547 arc_buf_contents_t type;
1548 if (HDR_ISTYPE_METADATA(hdr)) {
1549 type = ARC_BUFC_METADATA;
1551 type = ARC_BUFC_DATA;
1553 VERIFY3U(hdr->b_type, ==, type);
1558 arc_is_metadata(arc_buf_t *buf)
1560 return (HDR_ISTYPE_METADATA(buf->b_hdr) != 0);
1564 arc_bufc_to_flags(arc_buf_contents_t type)
1568 /* metadata field is 0 if buffer contains normal data */
1570 case ARC_BUFC_METADATA:
1571 return (ARC_FLAG_BUFC_METADATA);
1575 panic("undefined ARC buffer type!");
1576 return ((uint32_t)-1);
1580 arc_buf_thaw(arc_buf_t *buf)
1582 arc_buf_hdr_t *hdr = buf->b_hdr;
1584 ASSERT3P(hdr->b_l1hdr.b_state, ==, arc_anon);
1585 ASSERT(!HDR_IO_IN_PROGRESS(hdr));
1587 arc_cksum_verify(buf);
1590 * Compressed buffers do not manipulate the b_freeze_cksum.
1592 if (ARC_BUF_COMPRESSED(buf))
1595 ASSERT(HDR_HAS_L1HDR(hdr));
1596 arc_cksum_free(hdr);
1597 arc_buf_unwatch(buf);
1601 arc_buf_freeze(arc_buf_t *buf)
1603 if (!(zfs_flags & ZFS_DEBUG_MODIFY))
1606 if (ARC_BUF_COMPRESSED(buf))
1609 ASSERT(HDR_HAS_L1HDR(buf->b_hdr));
1610 arc_cksum_compute(buf);
1614 * The arc_buf_hdr_t's b_flags should never be modified directly. Instead,
1615 * the following functions should be used to ensure that the flags are
1616 * updated in a thread-safe way. When manipulating the flags either
1617 * the hash_lock must be held or the hdr must be undiscoverable. This
1618 * ensures that we're not racing with any other threads when updating
1622 arc_hdr_set_flags(arc_buf_hdr_t *hdr, arc_flags_t flags)
1624 ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
1625 hdr->b_flags |= flags;
1629 arc_hdr_clear_flags(arc_buf_hdr_t *hdr, arc_flags_t flags)
1631 ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
1632 hdr->b_flags &= ~flags;
1636 * Setting the compression bits in the arc_buf_hdr_t's b_flags is
1637 * done in a special way since we have to clear and set bits
1638 * at the same time. Consumers that wish to set the compression bits
1639 * must use this function to ensure that the flags are updated in
1640 * thread-safe manner.
1643 arc_hdr_set_compress(arc_buf_hdr_t *hdr, enum zio_compress cmp)
1645 ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
1648 * Holes and embedded blocks will always have a psize = 0 so
1649 * we ignore the compression of the blkptr and set the
1650 * want to uncompress them. Mark them as uncompressed.
1652 if (!zfs_compressed_arc_enabled || HDR_GET_PSIZE(hdr) == 0) {
1653 arc_hdr_clear_flags(hdr, ARC_FLAG_COMPRESSED_ARC);
1654 ASSERT(!HDR_COMPRESSION_ENABLED(hdr));
1656 arc_hdr_set_flags(hdr, ARC_FLAG_COMPRESSED_ARC);
1657 ASSERT(HDR_COMPRESSION_ENABLED(hdr));
1660 HDR_SET_COMPRESS(hdr, cmp);
1661 ASSERT3U(HDR_GET_COMPRESS(hdr), ==, cmp);
1665 * Looks for another buf on the same hdr which has the data decompressed, copies
1666 * from it, and returns true. If no such buf exists, returns false.
1669 arc_buf_try_copy_decompressed_data(arc_buf_t *buf)
1671 arc_buf_hdr_t *hdr = buf->b_hdr;
1672 boolean_t copied = B_FALSE;
1674 ASSERT(HDR_HAS_L1HDR(hdr));
1675 ASSERT3P(buf->b_data, !=, NULL);
1676 ASSERT(!ARC_BUF_COMPRESSED(buf));
1678 for (arc_buf_t *from = hdr->b_l1hdr.b_buf; from != NULL;
1679 from = from->b_next) {
1680 /* can't use our own data buffer */
1685 if (!ARC_BUF_COMPRESSED(from)) {
1686 memcpy(buf->b_data, from->b_data, arc_buf_size(buf));
1694 * There were no decompressed bufs, so there should not be a
1695 * checksum on the hdr either.
1697 if (zfs_flags & ZFS_DEBUG_MODIFY)
1698 EQUIV(!copied, hdr->b_l1hdr.b_freeze_cksum == NULL);
1705 * Allocates an ARC buf header that's in an evicted & L2-cached state.
1706 * This is used during l2arc reconstruction to make empty ARC buffers
1707 * which circumvent the regular disk->arc->l2arc path and instead come
1708 * into being in the reverse order, i.e. l2arc->arc.
1710 static arc_buf_hdr_t *
1711 arc_buf_alloc_l2only(size_t size, arc_buf_contents_t type, l2arc_dev_t *dev,
1712 dva_t dva, uint64_t daddr, int32_t psize, uint64_t birth,
1713 enum zio_compress compress, uint8_t complevel, boolean_t protected,
1714 boolean_t prefetch, arc_state_type_t arcs_state)
1719 hdr = kmem_cache_alloc(hdr_l2only_cache, KM_SLEEP);
1720 hdr->b_birth = birth;
1723 arc_hdr_set_flags(hdr, arc_bufc_to_flags(type) | ARC_FLAG_HAS_L2HDR);
1724 HDR_SET_LSIZE(hdr, size);
1725 HDR_SET_PSIZE(hdr, psize);
1726 arc_hdr_set_compress(hdr, compress);
1727 hdr->b_complevel = complevel;
1729 arc_hdr_set_flags(hdr, ARC_FLAG_PROTECTED);
1731 arc_hdr_set_flags(hdr, ARC_FLAG_PREFETCH);
1732 hdr->b_spa = spa_load_guid(dev->l2ad_vdev->vdev_spa);
1736 hdr->b_l2hdr.b_dev = dev;
1737 hdr->b_l2hdr.b_daddr = daddr;
1738 hdr->b_l2hdr.b_arcs_state = arcs_state;
1744 * Return the size of the block, b_pabd, that is stored in the arc_buf_hdr_t.
1747 arc_hdr_size(arc_buf_hdr_t *hdr)
1751 if (arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF &&
1752 HDR_GET_PSIZE(hdr) > 0) {
1753 size = HDR_GET_PSIZE(hdr);
1755 ASSERT3U(HDR_GET_LSIZE(hdr), !=, 0);
1756 size = HDR_GET_LSIZE(hdr);
1762 arc_hdr_authenticate(arc_buf_hdr_t *hdr, spa_t *spa, uint64_t dsobj)
1766 uint64_t lsize = HDR_GET_LSIZE(hdr);
1767 uint64_t psize = HDR_GET_PSIZE(hdr);
1768 void *tmpbuf = NULL;
1769 abd_t *abd = hdr->b_l1hdr.b_pabd;
1771 ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
1772 ASSERT(HDR_AUTHENTICATED(hdr));
1773 ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
1776 * The MAC is calculated on the compressed data that is stored on disk.
1777 * However, if compressed arc is disabled we will only have the
1778 * decompressed data available to us now. Compress it into a temporary
1779 * abd so we can verify the MAC. The performance overhead of this will
1780 * be relatively low, since most objects in an encrypted objset will
1781 * be encrypted (instead of authenticated) anyway.
1783 if (HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF &&
1784 !HDR_COMPRESSION_ENABLED(hdr)) {
1786 csize = zio_compress_data(HDR_GET_COMPRESS(hdr),
1787 hdr->b_l1hdr.b_pabd, &tmpbuf, lsize, hdr->b_complevel);
1788 ASSERT3P(tmpbuf, !=, NULL);
1789 ASSERT3U(csize, <=, psize);
1790 abd = abd_get_from_buf(tmpbuf, lsize);
1791 abd_take_ownership_of_buf(abd, B_TRUE);
1792 abd_zero_off(abd, csize, psize - csize);
1796 * Authentication is best effort. We authenticate whenever the key is
1797 * available. If we succeed we clear ARC_FLAG_NOAUTH.
1799 if (hdr->b_crypt_hdr.b_ot == DMU_OT_OBJSET) {
1800 ASSERT3U(HDR_GET_COMPRESS(hdr), ==, ZIO_COMPRESS_OFF);
1801 ASSERT3U(lsize, ==, psize);
1802 ret = spa_do_crypt_objset_mac_abd(B_FALSE, spa, dsobj, abd,
1803 psize, hdr->b_l1hdr.b_byteswap != DMU_BSWAP_NUMFUNCS);
1805 ret = spa_do_crypt_mac_abd(B_FALSE, spa, dsobj, abd, psize,
1806 hdr->b_crypt_hdr.b_mac);
1810 arc_hdr_clear_flags(hdr, ARC_FLAG_NOAUTH);
1811 else if (ret != ENOENT)
1827 * This function will take a header that only has raw encrypted data in
1828 * b_crypt_hdr.b_rabd and decrypt it into a new buffer which is stored in
1829 * b_l1hdr.b_pabd. If designated in the header flags, this function will
1830 * also decompress the data.
1833 arc_hdr_decrypt(arc_buf_hdr_t *hdr, spa_t *spa, const zbookmark_phys_t *zb)
1838 boolean_t no_crypt = B_FALSE;
1839 boolean_t bswap = (hdr->b_l1hdr.b_byteswap != DMU_BSWAP_NUMFUNCS);
1841 ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
1842 ASSERT(HDR_ENCRYPTED(hdr));
1844 arc_hdr_alloc_abd(hdr, 0);
1846 ret = spa_do_crypt_abd(B_FALSE, spa, zb, hdr->b_crypt_hdr.b_ot,
1847 B_FALSE, bswap, hdr->b_crypt_hdr.b_salt, hdr->b_crypt_hdr.b_iv,
1848 hdr->b_crypt_hdr.b_mac, HDR_GET_PSIZE(hdr), hdr->b_l1hdr.b_pabd,
1849 hdr->b_crypt_hdr.b_rabd, &no_crypt);
1854 abd_copy(hdr->b_l1hdr.b_pabd, hdr->b_crypt_hdr.b_rabd,
1855 HDR_GET_PSIZE(hdr));
1859 * If this header has disabled arc compression but the b_pabd is
1860 * compressed after decrypting it, we need to decompress the newly
1863 if (HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF &&
1864 !HDR_COMPRESSION_ENABLED(hdr)) {
1866 * We want to make sure that we are correctly honoring the
1867 * zfs_abd_scatter_enabled setting, so we allocate an abd here
1868 * and then loan a buffer from it, rather than allocating a
1869 * linear buffer and wrapping it in an abd later.
1871 cabd = arc_get_data_abd(hdr, arc_hdr_size(hdr), hdr, 0);
1872 tmp = abd_borrow_buf(cabd, arc_hdr_size(hdr));
1874 ret = zio_decompress_data(HDR_GET_COMPRESS(hdr),
1875 hdr->b_l1hdr.b_pabd, tmp, HDR_GET_PSIZE(hdr),
1876 HDR_GET_LSIZE(hdr), &hdr->b_complevel);
1878 abd_return_buf(cabd, tmp, arc_hdr_size(hdr));
1882 abd_return_buf_copy(cabd, tmp, arc_hdr_size(hdr));
1883 arc_free_data_abd(hdr, hdr->b_l1hdr.b_pabd,
1884 arc_hdr_size(hdr), hdr);
1885 hdr->b_l1hdr.b_pabd = cabd;
1891 arc_hdr_free_abd(hdr, B_FALSE);
1893 arc_free_data_buf(hdr, cabd, arc_hdr_size(hdr), hdr);
1899 * This function is called during arc_buf_fill() to prepare the header's
1900 * abd plaintext pointer for use. This involves authenticated protected
1901 * data and decrypting encrypted data into the plaintext abd.
1904 arc_fill_hdr_crypt(arc_buf_hdr_t *hdr, kmutex_t *hash_lock, spa_t *spa,
1905 const zbookmark_phys_t *zb, boolean_t noauth)
1909 ASSERT(HDR_PROTECTED(hdr));
1911 if (hash_lock != NULL)
1912 mutex_enter(hash_lock);
1914 if (HDR_NOAUTH(hdr) && !noauth) {
1916 * The caller requested authenticated data but our data has
1917 * not been authenticated yet. Verify the MAC now if we can.
1919 ret = arc_hdr_authenticate(hdr, spa, zb->zb_objset);
1922 } else if (HDR_HAS_RABD(hdr) && hdr->b_l1hdr.b_pabd == NULL) {
1924 * If we only have the encrypted version of the data, but the
1925 * unencrypted version was requested we take this opportunity
1926 * to store the decrypted version in the header for future use.
1928 ret = arc_hdr_decrypt(hdr, spa, zb);
1933 ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
1935 if (hash_lock != NULL)
1936 mutex_exit(hash_lock);
1941 if (hash_lock != NULL)
1942 mutex_exit(hash_lock);
1948 * This function is used by the dbuf code to decrypt bonus buffers in place.
1949 * The dbuf code itself doesn't have any locking for decrypting a shared dnode
1950 * block, so we use the hash lock here to protect against concurrent calls to
1954 arc_buf_untransform_in_place(arc_buf_t *buf)
1956 arc_buf_hdr_t *hdr = buf->b_hdr;
1958 ASSERT(HDR_ENCRYPTED(hdr));
1959 ASSERT3U(hdr->b_crypt_hdr.b_ot, ==, DMU_OT_DNODE);
1960 ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
1961 ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
1963 zio_crypt_copy_dnode_bonus(hdr->b_l1hdr.b_pabd, buf->b_data,
1965 buf->b_flags &= ~ARC_BUF_FLAG_ENCRYPTED;
1966 buf->b_flags &= ~ARC_BUF_FLAG_COMPRESSED;
1970 * Given a buf that has a data buffer attached to it, this function will
1971 * efficiently fill the buf with data of the specified compression setting from
1972 * the hdr and update the hdr's b_freeze_cksum if necessary. If the buf and hdr
1973 * are already sharing a data buf, no copy is performed.
1975 * If the buf is marked as compressed but uncompressed data was requested, this
1976 * will allocate a new data buffer for the buf, remove that flag, and fill the
1977 * buf with uncompressed data. You can't request a compressed buf on a hdr with
1978 * uncompressed data, and (since we haven't added support for it yet) if you
1979 * want compressed data your buf must already be marked as compressed and have
1980 * the correct-sized data buffer.
1983 arc_buf_fill(arc_buf_t *buf, spa_t *spa, const zbookmark_phys_t *zb,
1984 arc_fill_flags_t flags)
1987 arc_buf_hdr_t *hdr = buf->b_hdr;
1988 boolean_t hdr_compressed =
1989 (arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF);
1990 boolean_t compressed = (flags & ARC_FILL_COMPRESSED) != 0;
1991 boolean_t encrypted = (flags & ARC_FILL_ENCRYPTED) != 0;
1992 dmu_object_byteswap_t bswap = hdr->b_l1hdr.b_byteswap;
1993 kmutex_t *hash_lock = (flags & ARC_FILL_LOCKED) ? NULL : HDR_LOCK(hdr);
1995 ASSERT3P(buf->b_data, !=, NULL);
1996 IMPLY(compressed, hdr_compressed || ARC_BUF_ENCRYPTED(buf));
1997 IMPLY(compressed, ARC_BUF_COMPRESSED(buf));
1998 IMPLY(encrypted, HDR_ENCRYPTED(hdr));
1999 IMPLY(encrypted, ARC_BUF_ENCRYPTED(buf));
2000 IMPLY(encrypted, ARC_BUF_COMPRESSED(buf));
2001 IMPLY(encrypted, !ARC_BUF_SHARED(buf));
2004 * If the caller wanted encrypted data we just need to copy it from
2005 * b_rabd and potentially byteswap it. We won't be able to do any
2006 * further transforms on it.
2009 ASSERT(HDR_HAS_RABD(hdr));
2010 abd_copy_to_buf(buf->b_data, hdr->b_crypt_hdr.b_rabd,
2011 HDR_GET_PSIZE(hdr));
2016 * Adjust encrypted and authenticated headers to accommodate
2017 * the request if needed. Dnode blocks (ARC_FILL_IN_PLACE) are
2018 * allowed to fail decryption due to keys not being loaded
2019 * without being marked as an IO error.
2021 if (HDR_PROTECTED(hdr)) {
2022 error = arc_fill_hdr_crypt(hdr, hash_lock, spa,
2023 zb, !!(flags & ARC_FILL_NOAUTH));
2024 if (error == EACCES && (flags & ARC_FILL_IN_PLACE) != 0) {
2026 } else if (error != 0) {
2027 if (hash_lock != NULL)
2028 mutex_enter(hash_lock);
2029 arc_hdr_set_flags(hdr, ARC_FLAG_IO_ERROR);
2030 if (hash_lock != NULL)
2031 mutex_exit(hash_lock);
2037 * There is a special case here for dnode blocks which are
2038 * decrypting their bonus buffers. These blocks may request to
2039 * be decrypted in-place. This is necessary because there may
2040 * be many dnodes pointing into this buffer and there is
2041 * currently no method to synchronize replacing the backing
2042 * b_data buffer and updating all of the pointers. Here we use
2043 * the hash lock to ensure there are no races. If the need
2044 * arises for other types to be decrypted in-place, they must
2045 * add handling here as well.
2047 if ((flags & ARC_FILL_IN_PLACE) != 0) {
2048 ASSERT(!hdr_compressed);
2049 ASSERT(!compressed);
2052 if (HDR_ENCRYPTED(hdr) && ARC_BUF_ENCRYPTED(buf)) {
2053 ASSERT3U(hdr->b_crypt_hdr.b_ot, ==, DMU_OT_DNODE);
2055 if (hash_lock != NULL)
2056 mutex_enter(hash_lock);
2057 arc_buf_untransform_in_place(buf);
2058 if (hash_lock != NULL)
2059 mutex_exit(hash_lock);
2061 /* Compute the hdr's checksum if necessary */
2062 arc_cksum_compute(buf);
2068 if (hdr_compressed == compressed) {
2069 if (!arc_buf_is_shared(buf)) {
2070 abd_copy_to_buf(buf->b_data, hdr->b_l1hdr.b_pabd,
2074 ASSERT(hdr_compressed);
2075 ASSERT(!compressed);
2078 * If the buf is sharing its data with the hdr, unlink it and
2079 * allocate a new data buffer for the buf.
2081 if (arc_buf_is_shared(buf)) {
2082 ASSERT(ARC_BUF_COMPRESSED(buf));
2084 /* We need to give the buf its own b_data */
2085 buf->b_flags &= ~ARC_BUF_FLAG_SHARED;
2087 arc_get_data_buf(hdr, HDR_GET_LSIZE(hdr), buf);
2088 arc_hdr_clear_flags(hdr, ARC_FLAG_SHARED_DATA);
2090 /* Previously overhead was 0; just add new overhead */
2091 ARCSTAT_INCR(arcstat_overhead_size, HDR_GET_LSIZE(hdr));
2092 } else if (ARC_BUF_COMPRESSED(buf)) {
2093 /* We need to reallocate the buf's b_data */
2094 arc_free_data_buf(hdr, buf->b_data, HDR_GET_PSIZE(hdr),
2097 arc_get_data_buf(hdr, HDR_GET_LSIZE(hdr), buf);
2099 /* We increased the size of b_data; update overhead */
2100 ARCSTAT_INCR(arcstat_overhead_size,
2101 HDR_GET_LSIZE(hdr) - HDR_GET_PSIZE(hdr));
2105 * Regardless of the buf's previous compression settings, it
2106 * should not be compressed at the end of this function.
2108 buf->b_flags &= ~ARC_BUF_FLAG_COMPRESSED;
2111 * Try copying the data from another buf which already has a
2112 * decompressed version. If that's not possible, it's time to
2113 * bite the bullet and decompress the data from the hdr.
2115 if (arc_buf_try_copy_decompressed_data(buf)) {
2116 /* Skip byteswapping and checksumming (already done) */
2119 error = zio_decompress_data(HDR_GET_COMPRESS(hdr),
2120 hdr->b_l1hdr.b_pabd, buf->b_data,
2121 HDR_GET_PSIZE(hdr), HDR_GET_LSIZE(hdr),
2125 * Absent hardware errors or software bugs, this should
2126 * be impossible, but log it anyway so we can debug it.
2130 "hdr %px, compress %d, psize %d, lsize %d",
2131 hdr, arc_hdr_get_compress(hdr),
2132 HDR_GET_PSIZE(hdr), HDR_GET_LSIZE(hdr));
2133 if (hash_lock != NULL)
2134 mutex_enter(hash_lock);
2135 arc_hdr_set_flags(hdr, ARC_FLAG_IO_ERROR);
2136 if (hash_lock != NULL)
2137 mutex_exit(hash_lock);
2138 return (SET_ERROR(EIO));
2144 /* Byteswap the buf's data if necessary */
2145 if (bswap != DMU_BSWAP_NUMFUNCS) {
2146 ASSERT(!HDR_SHARED_DATA(hdr));
2147 ASSERT3U(bswap, <, DMU_BSWAP_NUMFUNCS);
2148 dmu_ot_byteswap[bswap].ob_func(buf->b_data, HDR_GET_LSIZE(hdr));
2151 /* Compute the hdr's checksum if necessary */
2152 arc_cksum_compute(buf);
2158 * If this function is being called to decrypt an encrypted buffer or verify an
2159 * authenticated one, the key must be loaded and a mapping must be made
2160 * available in the keystore via spa_keystore_create_mapping() or one of its
2164 arc_untransform(arc_buf_t *buf, spa_t *spa, const zbookmark_phys_t *zb,
2168 arc_fill_flags_t flags = 0;
2171 flags |= ARC_FILL_IN_PLACE;
2173 ret = arc_buf_fill(buf, spa, zb, flags);
2174 if (ret == ECKSUM) {
2176 * Convert authentication and decryption errors to EIO
2177 * (and generate an ereport) before leaving the ARC.
2179 ret = SET_ERROR(EIO);
2180 spa_log_error(spa, zb, &buf->b_hdr->b_birth);
2181 (void) zfs_ereport_post(FM_EREPORT_ZFS_AUTHENTICATION,
2182 spa, NULL, zb, NULL, 0);
2189 * Increment the amount of evictable space in the arc_state_t's refcount.
2190 * We account for the space used by the hdr and the arc buf individually
2191 * so that we can add and remove them from the refcount individually.
2194 arc_evictable_space_increment(arc_buf_hdr_t *hdr, arc_state_t *state)
2196 arc_buf_contents_t type = arc_buf_type(hdr);
2198 ASSERT(HDR_HAS_L1HDR(hdr));
2200 if (GHOST_STATE(state)) {
2201 ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
2202 ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
2203 ASSERT(!HDR_HAS_RABD(hdr));
2204 (void) zfs_refcount_add_many(&state->arcs_esize[type],
2205 HDR_GET_LSIZE(hdr), hdr);
2209 if (hdr->b_l1hdr.b_pabd != NULL) {
2210 (void) zfs_refcount_add_many(&state->arcs_esize[type],
2211 arc_hdr_size(hdr), hdr);
2213 if (HDR_HAS_RABD(hdr)) {
2214 (void) zfs_refcount_add_many(&state->arcs_esize[type],
2215 HDR_GET_PSIZE(hdr), hdr);
2218 for (arc_buf_t *buf = hdr->b_l1hdr.b_buf; buf != NULL;
2219 buf = buf->b_next) {
2220 if (arc_buf_is_shared(buf))
2222 (void) zfs_refcount_add_many(&state->arcs_esize[type],
2223 arc_buf_size(buf), buf);
2228 * Decrement the amount of evictable space in the arc_state_t's refcount.
2229 * We account for the space used by the hdr and the arc buf individually
2230 * so that we can add and remove them from the refcount individually.
2233 arc_evictable_space_decrement(arc_buf_hdr_t *hdr, arc_state_t *state)
2235 arc_buf_contents_t type = arc_buf_type(hdr);
2237 ASSERT(HDR_HAS_L1HDR(hdr));
2239 if (GHOST_STATE(state)) {
2240 ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
2241 ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
2242 ASSERT(!HDR_HAS_RABD(hdr));
2243 (void) zfs_refcount_remove_many(&state->arcs_esize[type],
2244 HDR_GET_LSIZE(hdr), hdr);
2248 if (hdr->b_l1hdr.b_pabd != NULL) {
2249 (void) zfs_refcount_remove_many(&state->arcs_esize[type],
2250 arc_hdr_size(hdr), hdr);
2252 if (HDR_HAS_RABD(hdr)) {
2253 (void) zfs_refcount_remove_many(&state->arcs_esize[type],
2254 HDR_GET_PSIZE(hdr), hdr);
2257 for (arc_buf_t *buf = hdr->b_l1hdr.b_buf; buf != NULL;
2258 buf = buf->b_next) {
2259 if (arc_buf_is_shared(buf))
2261 (void) zfs_refcount_remove_many(&state->arcs_esize[type],
2262 arc_buf_size(buf), buf);
2267 * Add a reference to this hdr indicating that someone is actively
2268 * referencing that memory. When the refcount transitions from 0 to 1,
2269 * we remove it from the respective arc_state_t list to indicate that
2270 * it is not evictable.
2273 add_reference(arc_buf_hdr_t *hdr, const void *tag)
2275 arc_state_t *state = hdr->b_l1hdr.b_state;
2277 ASSERT(HDR_HAS_L1HDR(hdr));
2278 if (!HDR_EMPTY(hdr) && !MUTEX_HELD(HDR_LOCK(hdr))) {
2279 ASSERT(state == arc_anon);
2280 ASSERT(zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
2281 ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
2284 if ((zfs_refcount_add(&hdr->b_l1hdr.b_refcnt, tag) == 1) &&
2285 state != arc_anon && state != arc_l2c_only) {
2286 /* We don't use the L2-only state list. */
2287 multilist_remove(&state->arcs_list[arc_buf_type(hdr)], hdr);
2288 arc_evictable_space_decrement(hdr, state);
2293 * Remove a reference from this hdr. When the reference transitions from
2294 * 1 to 0 and we're not anonymous, then we add this hdr to the arc_state_t's
2295 * list making it eligible for eviction.
2298 remove_reference(arc_buf_hdr_t *hdr, const void *tag)
2301 arc_state_t *state = hdr->b_l1hdr.b_state;
2303 ASSERT(HDR_HAS_L1HDR(hdr));
2304 ASSERT(state == arc_anon || MUTEX_HELD(HDR_LOCK(hdr)));
2305 ASSERT(!GHOST_STATE(state)); /* arc_l2c_only counts as a ghost. */
2307 if ((cnt = zfs_refcount_remove(&hdr->b_l1hdr.b_refcnt, tag)) != 0)
2310 if (state == arc_anon) {
2311 arc_hdr_destroy(hdr);
2314 if (state == arc_uncached && !HDR_PREFETCH(hdr)) {
2315 arc_change_state(arc_anon, hdr);
2316 arc_hdr_destroy(hdr);
2319 multilist_insert(&state->arcs_list[arc_buf_type(hdr)], hdr);
2320 arc_evictable_space_increment(hdr, state);
2325 * Returns detailed information about a specific arc buffer. When the
2326 * state_index argument is set the function will calculate the arc header
2327 * list position for its arc state. Since this requires a linear traversal
2328 * callers are strongly encourage not to do this. However, it can be helpful
2329 * for targeted analysis so the functionality is provided.
2332 arc_buf_info(arc_buf_t *ab, arc_buf_info_t *abi, int state_index)
2335 arc_buf_hdr_t *hdr = ab->b_hdr;
2336 l1arc_buf_hdr_t *l1hdr = NULL;
2337 l2arc_buf_hdr_t *l2hdr = NULL;
2338 arc_state_t *state = NULL;
2340 memset(abi, 0, sizeof (arc_buf_info_t));
2345 abi->abi_flags = hdr->b_flags;
2347 if (HDR_HAS_L1HDR(hdr)) {
2348 l1hdr = &hdr->b_l1hdr;
2349 state = l1hdr->b_state;
2351 if (HDR_HAS_L2HDR(hdr))
2352 l2hdr = &hdr->b_l2hdr;
2355 abi->abi_bufcnt = 0;
2356 for (arc_buf_t *buf = l1hdr->b_buf; buf; buf = buf->b_next)
2358 abi->abi_access = l1hdr->b_arc_access;
2359 abi->abi_mru_hits = l1hdr->b_mru_hits;
2360 abi->abi_mru_ghost_hits = l1hdr->b_mru_ghost_hits;
2361 abi->abi_mfu_hits = l1hdr->b_mfu_hits;
2362 abi->abi_mfu_ghost_hits = l1hdr->b_mfu_ghost_hits;
2363 abi->abi_holds = zfs_refcount_count(&l1hdr->b_refcnt);
2367 abi->abi_l2arc_dattr = l2hdr->b_daddr;
2368 abi->abi_l2arc_hits = l2hdr->b_hits;
2371 abi->abi_state_type = state ? state->arcs_state : ARC_STATE_ANON;
2372 abi->abi_state_contents = arc_buf_type(hdr);
2373 abi->abi_size = arc_hdr_size(hdr);
2377 * Move the supplied buffer to the indicated state. The hash lock
2378 * for the buffer must be held by the caller.
2381 arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *hdr)
2383 arc_state_t *old_state;
2385 boolean_t update_old, update_new;
2386 arc_buf_contents_t type = arc_buf_type(hdr);
2389 * We almost always have an L1 hdr here, since we call arc_hdr_realloc()
2390 * in arc_read() when bringing a buffer out of the L2ARC. However, the
2391 * L1 hdr doesn't always exist when we change state to arc_anon before
2392 * destroying a header, in which case reallocating to add the L1 hdr is
2395 if (HDR_HAS_L1HDR(hdr)) {
2396 old_state = hdr->b_l1hdr.b_state;
2397 refcnt = zfs_refcount_count(&hdr->b_l1hdr.b_refcnt);
2398 update_old = (hdr->b_l1hdr.b_buf != NULL ||
2399 hdr->b_l1hdr.b_pabd != NULL || HDR_HAS_RABD(hdr));
2401 IMPLY(GHOST_STATE(old_state), hdr->b_l1hdr.b_buf == NULL);
2402 IMPLY(GHOST_STATE(new_state), hdr->b_l1hdr.b_buf == NULL);
2403 IMPLY(old_state == arc_anon, hdr->b_l1hdr.b_buf == NULL ||
2404 ARC_BUF_LAST(hdr->b_l1hdr.b_buf));
2406 old_state = arc_l2c_only;
2408 update_old = B_FALSE;
2410 update_new = update_old;
2411 if (GHOST_STATE(old_state))
2412 update_old = B_TRUE;
2413 if (GHOST_STATE(new_state))
2414 update_new = B_TRUE;
2416 ASSERT(MUTEX_HELD(HDR_LOCK(hdr)));
2417 ASSERT3P(new_state, !=, old_state);
2420 * If this buffer is evictable, transfer it from the
2421 * old state list to the new state list.
2424 if (old_state != arc_anon && old_state != arc_l2c_only) {
2425 ASSERT(HDR_HAS_L1HDR(hdr));
2426 /* remove_reference() saves on insert. */
2427 if (multilist_link_active(&hdr->b_l1hdr.b_arc_node)) {
2428 multilist_remove(&old_state->arcs_list[type],
2430 arc_evictable_space_decrement(hdr, old_state);
2433 if (new_state != arc_anon && new_state != arc_l2c_only) {
2435 * An L1 header always exists here, since if we're
2436 * moving to some L1-cached state (i.e. not l2c_only or
2437 * anonymous), we realloc the header to add an L1hdr
2440 ASSERT(HDR_HAS_L1HDR(hdr));
2441 multilist_insert(&new_state->arcs_list[type], hdr);
2442 arc_evictable_space_increment(hdr, new_state);
2446 ASSERT(!HDR_EMPTY(hdr));
2447 if (new_state == arc_anon && HDR_IN_HASH_TABLE(hdr))
2448 buf_hash_remove(hdr);
2450 /* adjust state sizes (ignore arc_l2c_only) */
2452 if (update_new && new_state != arc_l2c_only) {
2453 ASSERT(HDR_HAS_L1HDR(hdr));
2454 if (GHOST_STATE(new_state)) {
2457 * When moving a header to a ghost state, we first
2458 * remove all arc buffers. Thus, we'll have no arc
2459 * buffer to use for the reference. As a result, we
2460 * use the arc header pointer for the reference.
2462 (void) zfs_refcount_add_many(
2463 &new_state->arcs_size[type],
2464 HDR_GET_LSIZE(hdr), hdr);
2465 ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
2466 ASSERT(!HDR_HAS_RABD(hdr));
2470 * Each individual buffer holds a unique reference,
2471 * thus we must remove each of these references one
2474 for (arc_buf_t *buf = hdr->b_l1hdr.b_buf; buf != NULL;
2475 buf = buf->b_next) {
2478 * When the arc_buf_t is sharing the data
2479 * block with the hdr, the owner of the
2480 * reference belongs to the hdr. Only
2481 * add to the refcount if the arc_buf_t is
2484 if (arc_buf_is_shared(buf))
2487 (void) zfs_refcount_add_many(
2488 &new_state->arcs_size[type],
2489 arc_buf_size(buf), buf);
2492 if (hdr->b_l1hdr.b_pabd != NULL) {
2493 (void) zfs_refcount_add_many(
2494 &new_state->arcs_size[type],
2495 arc_hdr_size(hdr), hdr);
2498 if (HDR_HAS_RABD(hdr)) {
2499 (void) zfs_refcount_add_many(
2500 &new_state->arcs_size[type],
2501 HDR_GET_PSIZE(hdr), hdr);
2506 if (update_old && old_state != arc_l2c_only) {
2507 ASSERT(HDR_HAS_L1HDR(hdr));
2508 if (GHOST_STATE(old_state)) {
2509 ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
2510 ASSERT(!HDR_HAS_RABD(hdr));
2513 * When moving a header off of a ghost state,
2514 * the header will not contain any arc buffers.
2515 * We use the arc header pointer for the reference
2516 * which is exactly what we did when we put the
2517 * header on the ghost state.
2520 (void) zfs_refcount_remove_many(
2521 &old_state->arcs_size[type],
2522 HDR_GET_LSIZE(hdr), hdr);
2526 * Each individual buffer holds a unique reference,
2527 * thus we must remove each of these references one
2530 for (arc_buf_t *buf = hdr->b_l1hdr.b_buf; buf != NULL;
2531 buf = buf->b_next) {
2534 * When the arc_buf_t is sharing the data
2535 * block with the hdr, the owner of the
2536 * reference belongs to the hdr. Only
2537 * add to the refcount if the arc_buf_t is
2540 if (arc_buf_is_shared(buf))
2543 (void) zfs_refcount_remove_many(
2544 &old_state->arcs_size[type],
2545 arc_buf_size(buf), buf);
2547 ASSERT(hdr->b_l1hdr.b_pabd != NULL ||
2550 if (hdr->b_l1hdr.b_pabd != NULL) {
2551 (void) zfs_refcount_remove_many(
2552 &old_state->arcs_size[type],
2553 arc_hdr_size(hdr), hdr);
2556 if (HDR_HAS_RABD(hdr)) {
2557 (void) zfs_refcount_remove_many(
2558 &old_state->arcs_size[type],
2559 HDR_GET_PSIZE(hdr), hdr);
2564 if (HDR_HAS_L1HDR(hdr)) {
2565 hdr->b_l1hdr.b_state = new_state;
2567 if (HDR_HAS_L2HDR(hdr) && new_state != arc_l2c_only) {
2568 l2arc_hdr_arcstats_decrement_state(hdr);
2569 hdr->b_l2hdr.b_arcs_state = new_state->arcs_state;
2570 l2arc_hdr_arcstats_increment_state(hdr);
2576 arc_space_consume(uint64_t space, arc_space_type_t type)
2578 ASSERT(type >= 0 && type < ARC_SPACE_NUMTYPES);
2583 case ARC_SPACE_DATA:
2584 ARCSTAT_INCR(arcstat_data_size, space);
2586 case ARC_SPACE_META:
2587 ARCSTAT_INCR(arcstat_metadata_size, space);
2589 case ARC_SPACE_BONUS:
2590 ARCSTAT_INCR(arcstat_bonus_size, space);
2592 case ARC_SPACE_DNODE:
2593 ARCSTAT_INCR(arcstat_dnode_size, space);
2595 case ARC_SPACE_DBUF:
2596 ARCSTAT_INCR(arcstat_dbuf_size, space);
2598 case ARC_SPACE_HDRS:
2599 ARCSTAT_INCR(arcstat_hdr_size, space);
2601 case ARC_SPACE_L2HDRS:
2602 aggsum_add(&arc_sums.arcstat_l2_hdr_size, space);
2604 case ARC_SPACE_ABD_CHUNK_WASTE:
2606 * Note: this includes space wasted by all scatter ABD's, not
2607 * just those allocated by the ARC. But the vast majority of
2608 * scatter ABD's come from the ARC, because other users are
2611 ARCSTAT_INCR(arcstat_abd_chunk_waste_size, space);
2615 if (type != ARC_SPACE_DATA && type != ARC_SPACE_ABD_CHUNK_WASTE)
2616 ARCSTAT_INCR(arcstat_meta_used, space);
2618 aggsum_add(&arc_sums.arcstat_size, space);
2622 arc_space_return(uint64_t space, arc_space_type_t type)
2624 ASSERT(type >= 0 && type < ARC_SPACE_NUMTYPES);
2629 case ARC_SPACE_DATA:
2630 ARCSTAT_INCR(arcstat_data_size, -space);
2632 case ARC_SPACE_META:
2633 ARCSTAT_INCR(arcstat_metadata_size, -space);
2635 case ARC_SPACE_BONUS:
2636 ARCSTAT_INCR(arcstat_bonus_size, -space);
2638 case ARC_SPACE_DNODE:
2639 ARCSTAT_INCR(arcstat_dnode_size, -space);
2641 case ARC_SPACE_DBUF:
2642 ARCSTAT_INCR(arcstat_dbuf_size, -space);
2644 case ARC_SPACE_HDRS:
2645 ARCSTAT_INCR(arcstat_hdr_size, -space);
2647 case ARC_SPACE_L2HDRS:
2648 aggsum_add(&arc_sums.arcstat_l2_hdr_size, -space);
2650 case ARC_SPACE_ABD_CHUNK_WASTE:
2651 ARCSTAT_INCR(arcstat_abd_chunk_waste_size, -space);
2655 if (type != ARC_SPACE_DATA && type != ARC_SPACE_ABD_CHUNK_WASTE)
2656 ARCSTAT_INCR(arcstat_meta_used, -space);
2658 ASSERT(aggsum_compare(&arc_sums.arcstat_size, space) >= 0);
2659 aggsum_add(&arc_sums.arcstat_size, -space);
2663 * Given a hdr and a buf, returns whether that buf can share its b_data buffer
2664 * with the hdr's b_pabd.
2667 arc_can_share(arc_buf_hdr_t *hdr, arc_buf_t *buf)
2670 * The criteria for sharing a hdr's data are:
2671 * 1. the buffer is not encrypted
2672 * 2. the hdr's compression matches the buf's compression
2673 * 3. the hdr doesn't need to be byteswapped
2674 * 4. the hdr isn't already being shared
2675 * 5. the buf is either compressed or it is the last buf in the hdr list
2677 * Criterion #5 maintains the invariant that shared uncompressed
2678 * bufs must be the final buf in the hdr's b_buf list. Reading this, you
2679 * might ask, "if a compressed buf is allocated first, won't that be the
2680 * last thing in the list?", but in that case it's impossible to create
2681 * a shared uncompressed buf anyway (because the hdr must be compressed
2682 * to have the compressed buf). You might also think that #3 is
2683 * sufficient to make this guarantee, however it's possible
2684 * (specifically in the rare L2ARC write race mentioned in
2685 * arc_buf_alloc_impl()) there will be an existing uncompressed buf that
2686 * is shareable, but wasn't at the time of its allocation. Rather than
2687 * allow a new shared uncompressed buf to be created and then shuffle
2688 * the list around to make it the last element, this simply disallows
2689 * sharing if the new buf isn't the first to be added.
2691 ASSERT3P(buf->b_hdr, ==, hdr);
2692 boolean_t hdr_compressed =
2693 arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF;
2694 boolean_t buf_compressed = ARC_BUF_COMPRESSED(buf) != 0;
2695 return (!ARC_BUF_ENCRYPTED(buf) &&
2696 buf_compressed == hdr_compressed &&
2697 hdr->b_l1hdr.b_byteswap == DMU_BSWAP_NUMFUNCS &&
2698 !HDR_SHARED_DATA(hdr) &&
2699 (ARC_BUF_LAST(buf) || ARC_BUF_COMPRESSED(buf)));
2703 * Allocate a buf for this hdr. If you care about the data that's in the hdr,
2704 * or if you want a compressed buffer, pass those flags in. Returns 0 if the
2705 * copy was made successfully, or an error code otherwise.
2708 arc_buf_alloc_impl(arc_buf_hdr_t *hdr, spa_t *spa, const zbookmark_phys_t *zb,
2709 const void *tag, boolean_t encrypted, boolean_t compressed,
2710 boolean_t noauth, boolean_t fill, arc_buf_t **ret)
2713 arc_fill_flags_t flags = ARC_FILL_LOCKED;
2715 ASSERT(HDR_HAS_L1HDR(hdr));
2716 ASSERT3U(HDR_GET_LSIZE(hdr), >, 0);
2717 VERIFY(hdr->b_type == ARC_BUFC_DATA ||
2718 hdr->b_type == ARC_BUFC_METADATA);
2719 ASSERT3P(ret, !=, NULL);
2720 ASSERT3P(*ret, ==, NULL);
2721 IMPLY(encrypted, compressed);
2723 buf = *ret = kmem_cache_alloc(buf_cache, KM_PUSHPAGE);
2726 buf->b_next = hdr->b_l1hdr.b_buf;
2729 add_reference(hdr, tag);
2732 * We're about to change the hdr's b_flags. We must either
2733 * hold the hash_lock or be undiscoverable.
2735 ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
2738 * Only honor requests for compressed bufs if the hdr is actually
2739 * compressed. This must be overridden if the buffer is encrypted since
2740 * encrypted buffers cannot be decompressed.
2743 buf->b_flags |= ARC_BUF_FLAG_COMPRESSED;
2744 buf->b_flags |= ARC_BUF_FLAG_ENCRYPTED;
2745 flags |= ARC_FILL_COMPRESSED | ARC_FILL_ENCRYPTED;
2746 } else if (compressed &&
2747 arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF) {
2748 buf->b_flags |= ARC_BUF_FLAG_COMPRESSED;
2749 flags |= ARC_FILL_COMPRESSED;
2754 flags |= ARC_FILL_NOAUTH;
2758 * If the hdr's data can be shared then we share the data buffer and
2759 * set the appropriate bit in the hdr's b_flags to indicate the hdr is
2760 * sharing it's b_pabd with the arc_buf_t. Otherwise, we allocate a new
2761 * buffer to store the buf's data.
2763 * There are two additional restrictions here because we're sharing
2764 * hdr -> buf instead of the usual buf -> hdr. First, the hdr can't be
2765 * actively involved in an L2ARC write, because if this buf is used by
2766 * an arc_write() then the hdr's data buffer will be released when the
2767 * write completes, even though the L2ARC write might still be using it.
2768 * Second, the hdr's ABD must be linear so that the buf's user doesn't
2769 * need to be ABD-aware. It must be allocated via
2770 * zio_[data_]buf_alloc(), not as a page, because we need to be able
2771 * to abd_release_ownership_of_buf(), which isn't allowed on "linear
2772 * page" buffers because the ABD code needs to handle freeing them
2775 boolean_t can_share = arc_can_share(hdr, buf) &&
2776 !HDR_L2_WRITING(hdr) &&
2777 hdr->b_l1hdr.b_pabd != NULL &&
2778 abd_is_linear(hdr->b_l1hdr.b_pabd) &&
2779 !abd_is_linear_page(hdr->b_l1hdr.b_pabd);
2781 /* Set up b_data and sharing */
2783 buf->b_data = abd_to_buf(hdr->b_l1hdr.b_pabd);
2784 buf->b_flags |= ARC_BUF_FLAG_SHARED;
2785 arc_hdr_set_flags(hdr, ARC_FLAG_SHARED_DATA);
2788 arc_get_data_buf(hdr, arc_buf_size(buf), buf);
2789 ARCSTAT_INCR(arcstat_overhead_size, arc_buf_size(buf));
2791 VERIFY3P(buf->b_data, !=, NULL);
2793 hdr->b_l1hdr.b_buf = buf;
2796 * If the user wants the data from the hdr, we need to either copy or
2797 * decompress the data.
2800 ASSERT3P(zb, !=, NULL);
2801 return (arc_buf_fill(buf, spa, zb, flags));
2807 static const char *arc_onloan_tag = "onloan";
2810 arc_loaned_bytes_update(int64_t delta)
2812 atomic_add_64(&arc_loaned_bytes, delta);
2814 /* assert that it did not wrap around */
2815 ASSERT3S(atomic_add_64_nv(&arc_loaned_bytes, 0), >=, 0);
2819 * Loan out an anonymous arc buffer. Loaned buffers are not counted as in
2820 * flight data by arc_tempreserve_space() until they are "returned". Loaned
2821 * buffers must be returned to the arc before they can be used by the DMU or
2825 arc_loan_buf(spa_t *spa, boolean_t is_metadata, int size)
2827 arc_buf_t *buf = arc_alloc_buf(spa, arc_onloan_tag,
2828 is_metadata ? ARC_BUFC_METADATA : ARC_BUFC_DATA, size);
2830 arc_loaned_bytes_update(arc_buf_size(buf));
2836 arc_loan_compressed_buf(spa_t *spa, uint64_t psize, uint64_t lsize,
2837 enum zio_compress compression_type, uint8_t complevel)
2839 arc_buf_t *buf = arc_alloc_compressed_buf(spa, arc_onloan_tag,
2840 psize, lsize, compression_type, complevel);
2842 arc_loaned_bytes_update(arc_buf_size(buf));
2848 arc_loan_raw_buf(spa_t *spa, uint64_t dsobj, boolean_t byteorder,
2849 const uint8_t *salt, const uint8_t *iv, const uint8_t *mac,
2850 dmu_object_type_t ot, uint64_t psize, uint64_t lsize,
2851 enum zio_compress compression_type, uint8_t complevel)
2853 arc_buf_t *buf = arc_alloc_raw_buf(spa, arc_onloan_tag, dsobj,
2854 byteorder, salt, iv, mac, ot, psize, lsize, compression_type,
2857 atomic_add_64(&arc_loaned_bytes, psize);
2863 * Return a loaned arc buffer to the arc.
2866 arc_return_buf(arc_buf_t *buf, const void *tag)
2868 arc_buf_hdr_t *hdr = buf->b_hdr;
2870 ASSERT3P(buf->b_data, !=, NULL);
2871 ASSERT(HDR_HAS_L1HDR(hdr));
2872 (void) zfs_refcount_add(&hdr->b_l1hdr.b_refcnt, tag);
2873 (void) zfs_refcount_remove(&hdr->b_l1hdr.b_refcnt, arc_onloan_tag);
2875 arc_loaned_bytes_update(-arc_buf_size(buf));
2878 /* Detach an arc_buf from a dbuf (tag) */
2880 arc_loan_inuse_buf(arc_buf_t *buf, const void *tag)
2882 arc_buf_hdr_t *hdr = buf->b_hdr;
2884 ASSERT3P(buf->b_data, !=, NULL);
2885 ASSERT(HDR_HAS_L1HDR(hdr));
2886 (void) zfs_refcount_add(&hdr->b_l1hdr.b_refcnt, arc_onloan_tag);
2887 (void) zfs_refcount_remove(&hdr->b_l1hdr.b_refcnt, tag);
2889 arc_loaned_bytes_update(arc_buf_size(buf));
2893 l2arc_free_abd_on_write(abd_t *abd, size_t size, arc_buf_contents_t type)
2895 l2arc_data_free_t *df = kmem_alloc(sizeof (*df), KM_SLEEP);
2898 df->l2df_size = size;
2899 df->l2df_type = type;
2900 mutex_enter(&l2arc_free_on_write_mtx);
2901 list_insert_head(l2arc_free_on_write, df);
2902 mutex_exit(&l2arc_free_on_write_mtx);
2906 arc_hdr_free_on_write(arc_buf_hdr_t *hdr, boolean_t free_rdata)
2908 arc_state_t *state = hdr->b_l1hdr.b_state;
2909 arc_buf_contents_t type = arc_buf_type(hdr);
2910 uint64_t size = (free_rdata) ? HDR_GET_PSIZE(hdr) : arc_hdr_size(hdr);
2912 /* protected by hash lock, if in the hash table */
2913 if (multilist_link_active(&hdr->b_l1hdr.b_arc_node)) {
2914 ASSERT(zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
2915 ASSERT(state != arc_anon && state != arc_l2c_only);
2917 (void) zfs_refcount_remove_many(&state->arcs_esize[type],
2920 (void) zfs_refcount_remove_many(&state->arcs_size[type], size, hdr);
2921 if (type == ARC_BUFC_METADATA) {
2922 arc_space_return(size, ARC_SPACE_META);
2924 ASSERT(type == ARC_BUFC_DATA);
2925 arc_space_return(size, ARC_SPACE_DATA);
2929 l2arc_free_abd_on_write(hdr->b_crypt_hdr.b_rabd, size, type);
2931 l2arc_free_abd_on_write(hdr->b_l1hdr.b_pabd, size, type);
2936 * Share the arc_buf_t's data with the hdr. Whenever we are sharing the
2937 * data buffer, we transfer the refcount ownership to the hdr and update
2938 * the appropriate kstats.
2941 arc_share_buf(arc_buf_hdr_t *hdr, arc_buf_t *buf)
2943 ASSERT(arc_can_share(hdr, buf));
2944 ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
2945 ASSERT(!ARC_BUF_ENCRYPTED(buf));
2946 ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
2949 * Start sharing the data buffer. We transfer the
2950 * refcount ownership to the hdr since it always owns
2951 * the refcount whenever an arc_buf_t is shared.
2953 zfs_refcount_transfer_ownership_many(
2954 &hdr->b_l1hdr.b_state->arcs_size[arc_buf_type(hdr)],
2955 arc_hdr_size(hdr), buf, hdr);
2956 hdr->b_l1hdr.b_pabd = abd_get_from_buf(buf->b_data, arc_buf_size(buf));
2957 abd_take_ownership_of_buf(hdr->b_l1hdr.b_pabd,
2958 HDR_ISTYPE_METADATA(hdr));
2959 arc_hdr_set_flags(hdr, ARC_FLAG_SHARED_DATA);
2960 buf->b_flags |= ARC_BUF_FLAG_SHARED;
2963 * Since we've transferred ownership to the hdr we need
2964 * to increment its compressed and uncompressed kstats and
2965 * decrement the overhead size.
2967 ARCSTAT_INCR(arcstat_compressed_size, arc_hdr_size(hdr));
2968 ARCSTAT_INCR(arcstat_uncompressed_size, HDR_GET_LSIZE(hdr));
2969 ARCSTAT_INCR(arcstat_overhead_size, -arc_buf_size(buf));
2973 arc_unshare_buf(arc_buf_hdr_t *hdr, arc_buf_t *buf)
2975 ASSERT(arc_buf_is_shared(buf));
2976 ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
2977 ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
2980 * We are no longer sharing this buffer so we need
2981 * to transfer its ownership to the rightful owner.
2983 zfs_refcount_transfer_ownership_many(
2984 &hdr->b_l1hdr.b_state->arcs_size[arc_buf_type(hdr)],
2985 arc_hdr_size(hdr), hdr, buf);
2986 arc_hdr_clear_flags(hdr, ARC_FLAG_SHARED_DATA);
2987 abd_release_ownership_of_buf(hdr->b_l1hdr.b_pabd);
2988 abd_free(hdr->b_l1hdr.b_pabd);
2989 hdr->b_l1hdr.b_pabd = NULL;
2990 buf->b_flags &= ~ARC_BUF_FLAG_SHARED;
2993 * Since the buffer is no longer shared between
2994 * the arc buf and the hdr, count it as overhead.
2996 ARCSTAT_INCR(arcstat_compressed_size, -arc_hdr_size(hdr));
2997 ARCSTAT_INCR(arcstat_uncompressed_size, -HDR_GET_LSIZE(hdr));
2998 ARCSTAT_INCR(arcstat_overhead_size, arc_buf_size(buf));
3002 * Remove an arc_buf_t from the hdr's buf list and return the last
3003 * arc_buf_t on the list. If no buffers remain on the list then return
3007 arc_buf_remove(arc_buf_hdr_t *hdr, arc_buf_t *buf)
3009 ASSERT(HDR_HAS_L1HDR(hdr));
3010 ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
3012 arc_buf_t **bufp = &hdr->b_l1hdr.b_buf;
3013 arc_buf_t *lastbuf = NULL;
3016 * Remove the buf from the hdr list and locate the last
3017 * remaining buffer on the list.
3019 while (*bufp != NULL) {
3021 *bufp = buf->b_next;
3024 * If we've removed a buffer in the middle of
3025 * the list then update the lastbuf and update
3028 if (*bufp != NULL) {
3030 bufp = &(*bufp)->b_next;
3034 ASSERT3P(lastbuf, !=, buf);
3035 IMPLY(lastbuf != NULL, ARC_BUF_LAST(lastbuf));
3041 * Free up buf->b_data and pull the arc_buf_t off of the arc_buf_hdr_t's
3045 arc_buf_destroy_impl(arc_buf_t *buf)
3047 arc_buf_hdr_t *hdr = buf->b_hdr;
3050 * Free up the data associated with the buf but only if we're not
3051 * sharing this with the hdr. If we are sharing it with the hdr, the
3052 * hdr is responsible for doing the free.
3054 if (buf->b_data != NULL) {
3056 * We're about to change the hdr's b_flags. We must either
3057 * hold the hash_lock or be undiscoverable.
3059 ASSERT(HDR_EMPTY_OR_LOCKED(hdr));
3061 arc_cksum_verify(buf);
3062 arc_buf_unwatch(buf);
3064 if (arc_buf_is_shared(buf)) {
3065 arc_hdr_clear_flags(hdr, ARC_FLAG_SHARED_DATA);
3067 uint64_t size = arc_buf_size(buf);
3068 arc_free_data_buf(hdr, buf->b_data, size, buf);
3069 ARCSTAT_INCR(arcstat_overhead_size, -size);
3074 * If we have no more encrypted buffers and we've already
3075 * gotten a copy of the decrypted data we can free b_rabd
3076 * to save some space.
3078 if (ARC_BUF_ENCRYPTED(buf) && HDR_HAS_RABD(hdr) &&
3079 hdr->b_l1hdr.b_pabd != NULL && !HDR_IO_IN_PROGRESS(hdr)) {
3081 for (b = hdr->b_l1hdr.b_buf; b; b = b->b_next) {
3082 if (b != buf && ARC_BUF_ENCRYPTED(b))
3086 arc_hdr_free_abd(hdr, B_TRUE);
3090 arc_buf_t *lastbuf = arc_buf_remove(hdr, buf);
3092 if (ARC_BUF_SHARED(buf) && !ARC_BUF_COMPRESSED(buf)) {
3094 * If the current arc_buf_t is sharing its data buffer with the
3095 * hdr, then reassign the hdr's b_pabd to share it with the new
3096 * buffer at the end of the list. The shared buffer is always
3097 * the last one on the hdr's buffer list.
3099 * There is an equivalent case for compressed bufs, but since
3100 * they aren't guaranteed to be the last buf in the list and
3101 * that is an exceedingly rare case, we just allow that space be
3102 * wasted temporarily. We must also be careful not to share
3103 * encrypted buffers, since they cannot be shared.
3105 if (lastbuf != NULL && !ARC_BUF_ENCRYPTED(lastbuf)) {
3106 /* Only one buf can be shared at once */
3107 VERIFY(!arc_buf_is_shared(lastbuf));
3108 /* hdr is uncompressed so can't have compressed buf */
3109 VERIFY(!ARC_BUF_COMPRESSED(lastbuf));
3111 ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
3112 arc_hdr_free_abd(hdr, B_FALSE);
3115 * We must setup a new shared block between the
3116 * last buffer and the hdr. The data would have
3117 * been allocated by the arc buf so we need to transfer
3118 * ownership to the hdr since it's now being shared.
3120 arc_share_buf(hdr, lastbuf);
3122 } else if (HDR_SHARED_DATA(hdr)) {
3124 * Uncompressed shared buffers are always at the end
3125 * of the list. Compressed buffers don't have the
3126 * same requirements. This makes it hard to
3127 * simply assert that the lastbuf is shared so
3128 * we rely on the hdr's compression flags to determine
3129 * if we have a compressed, shared buffer.
3131 ASSERT3P(lastbuf, !=, NULL);
3132 ASSERT(arc_buf_is_shared(lastbuf) ||
3133 arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF);
3137 * Free the checksum if we're removing the last uncompressed buf from
3140 if (!arc_hdr_has_uncompressed_buf(hdr)) {
3141 arc_cksum_free(hdr);
3144 /* clean up the buf */
3146 kmem_cache_free(buf_cache, buf);
3150 arc_hdr_alloc_abd(arc_buf_hdr_t *hdr, int alloc_flags)
3153 boolean_t alloc_rdata = ((alloc_flags & ARC_HDR_ALLOC_RDATA) != 0);
3155 ASSERT3U(HDR_GET_LSIZE(hdr), >, 0);
3156 ASSERT(HDR_HAS_L1HDR(hdr));
3157 ASSERT(!HDR_SHARED_DATA(hdr) || alloc_rdata);
3158 IMPLY(alloc_rdata, HDR_PROTECTED(hdr));
3161 size = HDR_GET_PSIZE(hdr);
3162 ASSERT3P(hdr->b_crypt_hdr.b_rabd, ==, NULL);
3163 hdr->b_crypt_hdr.b_rabd = arc_get_data_abd(hdr, size, hdr,
3165 ASSERT3P(hdr->b_crypt_hdr.b_rabd, !=, NULL);
3166 ARCSTAT_INCR(arcstat_raw_size, size);
3168 size = arc_hdr_size(hdr);
3169 ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
3170 hdr->b_l1hdr.b_pabd = arc_get_data_abd(hdr, size, hdr,
3172 ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
3175 ARCSTAT_INCR(arcstat_compressed_size, size);
3176 ARCSTAT_INCR(arcstat_uncompressed_size, HDR_GET_LSIZE(hdr));
3180 arc_hdr_free_abd(arc_buf_hdr_t *hdr, boolean_t free_rdata)
3182 uint64_t size = (free_rdata) ? HDR_GET_PSIZE(hdr) : arc_hdr_size(hdr);
3184 ASSERT(HDR_HAS_L1HDR(hdr));
3185 ASSERT(hdr->b_l1hdr.b_pabd != NULL || HDR_HAS_RABD(hdr));
3186 IMPLY(free_rdata, HDR_HAS_RABD(hdr));
3189 * If the hdr is currently being written to the l2arc then
3190 * we defer freeing the data by adding it to the l2arc_free_on_write
3191 * list. The l2arc will free the data once it's finished
3192 * writing it to the l2arc device.
3194 if (HDR_L2_WRITING(hdr)) {
3195 arc_hdr_free_on_write(hdr, free_rdata);
3196 ARCSTAT_BUMP(arcstat_l2_free_on_write);
3197 } else if (free_rdata) {
3198 arc_free_data_abd(hdr, hdr->b_crypt_hdr.b_rabd, size, hdr);
3200 arc_free_data_abd(hdr, hdr->b_l1hdr.b_pabd, size, hdr);
3204 hdr->b_crypt_hdr.b_rabd = NULL;
3205 ARCSTAT_INCR(arcstat_raw_size, -size);
3207 hdr->b_l1hdr.b_pabd = NULL;
3210 if (hdr->b_l1hdr.b_pabd == NULL && !HDR_HAS_RABD(hdr))
3211 hdr->b_l1hdr.b_byteswap = DMU_BSWAP_NUMFUNCS;
3213 ARCSTAT_INCR(arcstat_compressed_size, -size);
3214 ARCSTAT_INCR(arcstat_uncompressed_size, -HDR_GET_LSIZE(hdr));
3218 * Allocate empty anonymous ARC header. The header will get its identity
3219 * assigned and buffers attached later as part of read or write operations.
3221 * In case of read arc_read() assigns header its identify (b_dva + b_birth),
3222 * inserts it into ARC hash to become globally visible and allocates physical
3223 * (b_pabd) or raw (b_rabd) ABD buffer to read into from disk. On disk read
3224 * completion arc_read_done() allocates ARC buffer(s) as needed, potentially
3225 * sharing one of them with the physical ABD buffer.
3227 * In case of write arc_alloc_buf() allocates ARC buffer to be filled with
3228 * data. Then after compression and/or encryption arc_write_ready() allocates
3229 * and fills (or potentially shares) physical (b_pabd) or raw (b_rabd) ABD
3230 * buffer. On disk write completion arc_write_done() assigns the header its
3231 * new identity (b_dva + b_birth) and inserts into ARC hash.
3233 * In case of partial overwrite the old data is read first as described. Then
3234 * arc_release() either allocates new anonymous ARC header and moves the ARC
3235 * buffer to it, or reuses the old ARC header by discarding its identity and
3236 * removing it from ARC hash. After buffer modification normal write process
3237 * follows as described.
3239 static arc_buf_hdr_t *
3240 arc_hdr_alloc(uint64_t spa, int32_t psize, int32_t lsize,
3241 boolean_t protected, enum zio_compress compression_type, uint8_t complevel,
3242 arc_buf_contents_t type)
3246 VERIFY(type == ARC_BUFC_DATA || type == ARC_BUFC_METADATA);
3247 hdr = kmem_cache_alloc(hdr_full_cache, KM_PUSHPAGE);
3249 ASSERT(HDR_EMPTY(hdr));
3251 ASSERT3P(hdr->b_l1hdr.b_freeze_cksum, ==, NULL);
3253 HDR_SET_PSIZE(hdr, psize);
3254 HDR_SET_LSIZE(hdr, lsize);
3258 arc_hdr_set_flags(hdr, arc_bufc_to_flags(type) | ARC_FLAG_HAS_L1HDR);
3259 arc_hdr_set_compress(hdr, compression_type);
3260 hdr->b_complevel = complevel;
3262 arc_hdr_set_flags(hdr, ARC_FLAG_PROTECTED);
3264 hdr->b_l1hdr.b_state = arc_anon;
3265 hdr->b_l1hdr.b_arc_access = 0;
3266 hdr->b_l1hdr.b_mru_hits = 0;
3267 hdr->b_l1hdr.b_mru_ghost_hits = 0;
3268 hdr->b_l1hdr.b_mfu_hits = 0;
3269 hdr->b_l1hdr.b_mfu_ghost_hits = 0;
3270 hdr->b_l1hdr.b_buf = NULL;
3272 ASSERT(zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
3278 * Transition between the two allocation states for the arc_buf_hdr struct.
3279 * The arc_buf_hdr struct can be allocated with (hdr_full_cache) or without
3280 * (hdr_l2only_cache) the fields necessary for the L1 cache - the smaller
3281 * version is used when a cache buffer is only in the L2ARC in order to reduce
3284 static arc_buf_hdr_t *
3285 arc_hdr_realloc(arc_buf_hdr_t *hdr, kmem_cache_t *old, kmem_cache_t *new)
3287 ASSERT(HDR_HAS_L2HDR(hdr));
3289 arc_buf_hdr_t *nhdr;
3290 l2arc_dev_t *dev = hdr->b_l2hdr.b_dev;
3292 ASSERT((old == hdr_full_cache && new == hdr_l2only_cache) ||
3293 (old == hdr_l2only_cache && new == hdr_full_cache));
3295 nhdr = kmem_cache_alloc(new, KM_PUSHPAGE);
3297 ASSERT(MUTEX_HELD(HDR_LOCK(hdr)));
3298 buf_hash_remove(hdr);
3300 memcpy(nhdr, hdr, HDR_L2ONLY_SIZE);
3302 if (new == hdr_full_cache) {
3303 arc_hdr_set_flags(nhdr, ARC_FLAG_HAS_L1HDR);
3305 * arc_access and arc_change_state need to be aware that a
3306 * header has just come out of L2ARC, so we set its state to
3307 * l2c_only even though it's about to change.
3309 nhdr->b_l1hdr.b_state = arc_l2c_only;
3311 /* Verify previous threads set to NULL before freeing */
3312 ASSERT3P(nhdr->b_l1hdr.b_pabd, ==, NULL);
3313 ASSERT(!HDR_HAS_RABD(hdr));
3315 ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
3317 ASSERT3P(hdr->b_l1hdr.b_freeze_cksum, ==, NULL);
3321 * If we've reached here, We must have been called from
3322 * arc_evict_hdr(), as such we should have already been
3323 * removed from any ghost list we were previously on
3324 * (which protects us from racing with arc_evict_state),
3325 * thus no locking is needed during this check.
3327 ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node));
3330 * A buffer must not be moved into the arc_l2c_only
3331 * state if it's not finished being written out to the
3332 * l2arc device. Otherwise, the b_l1hdr.b_pabd field
3333 * might try to be accessed, even though it was removed.
3335 VERIFY(!HDR_L2_WRITING(hdr));
3336 VERIFY3P(hdr->b_l1hdr.b_pabd, ==, NULL);
3337 ASSERT(!HDR_HAS_RABD(hdr));
3339 arc_hdr_clear_flags(nhdr, ARC_FLAG_HAS_L1HDR);
3342 * The header has been reallocated so we need to re-insert it into any
3345 (void) buf_hash_insert(nhdr, NULL);
3347 ASSERT(list_link_active(&hdr->b_l2hdr.b_l2node));
3349 mutex_enter(&dev->l2ad_mtx);
3352 * We must place the realloc'ed header back into the list at
3353 * the same spot. Otherwise, if it's placed earlier in the list,
3354 * l2arc_write_buffers() could find it during the function's
3355 * write phase, and try to write it out to the l2arc.
3357 list_insert_after(&dev->l2ad_buflist, hdr, nhdr);
3358 list_remove(&dev->l2ad_buflist, hdr);
3360 mutex_exit(&dev->l2ad_mtx);
3363 * Since we're using the pointer address as the tag when
3364 * incrementing and decrementing the l2ad_alloc refcount, we
3365 * must remove the old pointer (that we're about to destroy) and
3366 * add the new pointer to the refcount. Otherwise we'd remove
3367 * the wrong pointer address when calling arc_hdr_destroy() later.
3370 (void) zfs_refcount_remove_many(&dev->l2ad_alloc,
3371 arc_hdr_size(hdr), hdr);
3372 (void) zfs_refcount_add_many(&dev->l2ad_alloc,
3373 arc_hdr_size(nhdr), nhdr);
3375 buf_discard_identity(hdr);
3376 kmem_cache_free(old, hdr);
3382 * This function is used by the send / receive code to convert a newly
3383 * allocated arc_buf_t to one that is suitable for a raw encrypted write. It
3384 * is also used to allow the root objset block to be updated without altering
3385 * its embedded MACs. Both block types will always be uncompressed so we do not
3386 * have to worry about compression type or psize.
3389 arc_convert_to_raw(arc_buf_t *buf, uint64_t dsobj, boolean_t byteorder,
3390 dmu_object_type_t ot, const uint8_t *salt, const uint8_t *iv,
3393 arc_buf_hdr_t *hdr = buf->b_hdr;
3395 ASSERT(ot == DMU_OT_DNODE || ot == DMU_OT_OBJSET);
3396 ASSERT(HDR_HAS_L1HDR(hdr));
3397 ASSERT3P(hdr->b_l1hdr.b_state, ==, arc_anon);
3399 buf->b_flags |= (ARC_BUF_FLAG_COMPRESSED | ARC_BUF_FLAG_ENCRYPTED);
3400 arc_hdr_set_flags(hdr, ARC_FLAG_PROTECTED);
3401 hdr->b_crypt_hdr.b_dsobj = dsobj;
3402 hdr->b_crypt_hdr.b_ot = ot;
3403 hdr->b_l1hdr.b_byteswap = (byteorder == ZFS_HOST_BYTEORDER) ?
3404 DMU_BSWAP_NUMFUNCS : DMU_OT_BYTESWAP(ot);
3405 if (!arc_hdr_has_uncompressed_buf(hdr))
3406 arc_cksum_free(hdr);
3409 memcpy(hdr->b_crypt_hdr.b_salt, salt, ZIO_DATA_SALT_LEN);
3411 memcpy(hdr->b_crypt_hdr.b_iv, iv, ZIO_DATA_IV_LEN);
3413 memcpy(hdr->b_crypt_hdr.b_mac, mac, ZIO_DATA_MAC_LEN);
3417 * Allocate a new arc_buf_hdr_t and arc_buf_t and return the buf to the caller.
3418 * The buf is returned thawed since we expect the consumer to modify it.
3421 arc_alloc_buf(spa_t *spa, const void *tag, arc_buf_contents_t type,
3424 arc_buf_hdr_t *hdr = arc_hdr_alloc(spa_load_guid(spa), size, size,
3425 B_FALSE, ZIO_COMPRESS_OFF, 0, type);
3427 arc_buf_t *buf = NULL;
3428 VERIFY0(arc_buf_alloc_impl(hdr, spa, NULL, tag, B_FALSE, B_FALSE,
3429 B_FALSE, B_FALSE, &buf));
3436 * Allocate a compressed buf in the same manner as arc_alloc_buf. Don't use this
3437 * for bufs containing metadata.
3440 arc_alloc_compressed_buf(spa_t *spa, const void *tag, uint64_t psize,
3441 uint64_t lsize, enum zio_compress compression_type, uint8_t complevel)
3443 ASSERT3U(lsize, >, 0);
3444 ASSERT3U(lsize, >=, psize);
3445 ASSERT3U(compression_type, >, ZIO_COMPRESS_OFF);
3446 ASSERT3U(compression_type, <, ZIO_COMPRESS_FUNCTIONS);
3448 arc_buf_hdr_t *hdr = arc_hdr_alloc(spa_load_guid(spa), psize, lsize,
3449 B_FALSE, compression_type, complevel, ARC_BUFC_DATA);
3451 arc_buf_t *buf = NULL;
3452 VERIFY0(arc_buf_alloc_impl(hdr, spa, NULL, tag, B_FALSE,
3453 B_TRUE, B_FALSE, B_FALSE, &buf));
3457 * To ensure that the hdr has the correct data in it if we call
3458 * arc_untransform() on this buf before it's been written to disk,
3459 * it's easiest if we just set up sharing between the buf and the hdr.
3461 arc_share_buf(hdr, buf);
3467 arc_alloc_raw_buf(spa_t *spa, const void *tag, uint64_t dsobj,
3468 boolean_t byteorder, const uint8_t *salt, const uint8_t *iv,
3469 const uint8_t *mac, dmu_object_type_t ot, uint64_t psize, uint64_t lsize,
3470 enum zio_compress compression_type, uint8_t complevel)
3474 arc_buf_contents_t type = DMU_OT_IS_METADATA(ot) ?
3475 ARC_BUFC_METADATA : ARC_BUFC_DATA;
3477 ASSERT3U(lsize, >, 0);
3478 ASSERT3U(lsize, >=, psize);
3479 ASSERT3U(compression_type, >=, ZIO_COMPRESS_OFF);
3480 ASSERT3U(compression_type, <, ZIO_COMPRESS_FUNCTIONS);
3482 hdr = arc_hdr_alloc(spa_load_guid(spa), psize, lsize, B_TRUE,
3483 compression_type, complevel, type);
3485 hdr->b_crypt_hdr.b_dsobj = dsobj;
3486 hdr->b_crypt_hdr.b_ot = ot;
3487 hdr->b_l1hdr.b_byteswap = (byteorder == ZFS_HOST_BYTEORDER) ?
3488 DMU_BSWAP_NUMFUNCS : DMU_OT_BYTESWAP(ot);
3489 memcpy(hdr->b_crypt_hdr.b_salt, salt, ZIO_DATA_SALT_LEN);
3490 memcpy(hdr->b_crypt_hdr.b_iv, iv, ZIO_DATA_IV_LEN);
3491 memcpy(hdr->b_crypt_hdr.b_mac, mac, ZIO_DATA_MAC_LEN);
3494 * This buffer will be considered encrypted even if the ot is not an
3495 * encrypted type. It will become authenticated instead in
3496 * arc_write_ready().
3499 VERIFY0(arc_buf_alloc_impl(hdr, spa, NULL, tag, B_TRUE, B_TRUE,
3500 B_FALSE, B_FALSE, &buf));
3507 l2arc_hdr_arcstats_update(arc_buf_hdr_t *hdr, boolean_t incr,
3508 boolean_t state_only)
3510 l2arc_buf_hdr_t *l2hdr = &hdr->b_l2hdr;
3511 l2arc_dev_t *dev = l2hdr->b_dev;
3512 uint64_t lsize = HDR_GET_LSIZE(hdr);
3513 uint64_t psize = HDR_GET_PSIZE(hdr);
3514 uint64_t asize = vdev_psize_to_asize(dev->l2ad_vdev, psize);
3515 arc_buf_contents_t type = hdr->b_type;
3530 /* If the buffer is a prefetch, count it as such. */
3531 if (HDR_PREFETCH(hdr)) {
3532 ARCSTAT_INCR(arcstat_l2_prefetch_asize, asize_s);
3535 * We use the value stored in the L2 header upon initial
3536 * caching in L2ARC. This value will be updated in case
3537 * an MRU/MRU_ghost buffer transitions to MFU but the L2ARC
3538 * metadata (log entry) cannot currently be updated. Having
3539 * the ARC state in the L2 header solves the problem of a
3540 * possibly absent L1 header (apparent in buffers restored
3541 * from persistent L2ARC).
3543 switch (hdr->b_l2hdr.b_arcs_state) {
3544 case ARC_STATE_MRU_GHOST:
3546 ARCSTAT_INCR(arcstat_l2_mru_asize, asize_s);
3548 case ARC_STATE_MFU_GHOST:
3550 ARCSTAT_INCR(arcstat_l2_mfu_asize, asize_s);
3560 ARCSTAT_INCR(arcstat_l2_psize, psize_s);
3561 ARCSTAT_INCR(arcstat_l2_lsize, lsize_s);
3565 ARCSTAT_INCR(arcstat_l2_bufc_data_asize, asize_s);
3567 case ARC_BUFC_METADATA:
3568 ARCSTAT_INCR(arcstat_l2_bufc_metadata_asize, asize_s);
3577 arc_hdr_l2hdr_destroy(arc_buf_hdr_t *hdr)
3579 l2arc_buf_hdr_t *l2hdr = &hdr->b_l2hdr;
3580 l2arc_dev_t *dev = l2hdr->b_dev;
3581 uint64_t psize = HDR_GET_PSIZE(hdr);
3582 uint64_t asize = vdev_psize_to_asize(dev->l2ad_vdev, psize);
3584 ASSERT(MUTEX_HELD(&dev->l2ad_mtx));
3585 ASSERT(HDR_HAS_L2HDR(hdr));
3587 list_remove(&dev->l2ad_buflist, hdr);
3589 l2arc_hdr_arcstats_decrement(hdr);
3590 vdev_space_update(dev->l2ad_vdev, -asize, 0, 0);
3592 (void) zfs_refcount_remove_many(&dev->l2ad_alloc, arc_hdr_size(hdr),
3594 arc_hdr_clear_flags(hdr, ARC_FLAG_HAS_L2HDR);
3598 arc_hdr_destroy(arc_buf_hdr_t *hdr)
3600 if (HDR_HAS_L1HDR(hdr)) {
3601 ASSERT(zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
3602 ASSERT3P(hdr->b_l1hdr.b_state, ==, arc_anon);
3604 ASSERT(!HDR_IO_IN_PROGRESS(hdr));
3605 ASSERT(!HDR_IN_HASH_TABLE(hdr));
3607 if (HDR_HAS_L2HDR(hdr)) {
3608 l2arc_dev_t *dev = hdr->b_l2hdr.b_dev;
3609 boolean_t buflist_held = MUTEX_HELD(&dev->l2ad_mtx);
3612 mutex_enter(&dev->l2ad_mtx);
3615 * Even though we checked this conditional above, we
3616 * need to check this again now that we have the
3617 * l2ad_mtx. This is because we could be racing with
3618 * another thread calling l2arc_evict() which might have
3619 * destroyed this header's L2 portion as we were waiting
3620 * to acquire the l2ad_mtx. If that happens, we don't
3621 * want to re-destroy the header's L2 portion.
3623 if (HDR_HAS_L2HDR(hdr)) {
3625 if (!HDR_EMPTY(hdr))
3626 buf_discard_identity(hdr);
3628 arc_hdr_l2hdr_destroy(hdr);
3632 mutex_exit(&dev->l2ad_mtx);
3636 * The header's identify can only be safely discarded once it is no
3637 * longer discoverable. This requires removing it from the hash table
3638 * and the l2arc header list. After this point the hash lock can not
3639 * be used to protect the header.
3641 if (!HDR_EMPTY(hdr))
3642 buf_discard_identity(hdr);
3644 if (HDR_HAS_L1HDR(hdr)) {
3645 arc_cksum_free(hdr);
3647 while (hdr->b_l1hdr.b_buf != NULL)
3648 arc_buf_destroy_impl(hdr->b_l1hdr.b_buf);
3650 if (hdr->b_l1hdr.b_pabd != NULL)
3651 arc_hdr_free_abd(hdr, B_FALSE);
3653 if (HDR_HAS_RABD(hdr))
3654 arc_hdr_free_abd(hdr, B_TRUE);
3657 ASSERT3P(hdr->b_hash_next, ==, NULL);
3658 if (HDR_HAS_L1HDR(hdr)) {
3659 ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node));
3660 ASSERT3P(hdr->b_l1hdr.b_acb, ==, NULL);
3662 ASSERT3P(hdr->b_l1hdr.b_freeze_cksum, ==, NULL);
3664 kmem_cache_free(hdr_full_cache, hdr);
3666 kmem_cache_free(hdr_l2only_cache, hdr);
3671 arc_buf_destroy(arc_buf_t *buf, const void *tag)
3673 arc_buf_hdr_t *hdr = buf->b_hdr;
3675 if (hdr->b_l1hdr.b_state == arc_anon) {
3676 ASSERT3P(hdr->b_l1hdr.b_buf, ==, buf);
3677 ASSERT(ARC_BUF_LAST(buf));
3678 ASSERT(!HDR_IO_IN_PROGRESS(hdr));
3679 VERIFY0(remove_reference(hdr, tag));
3683 kmutex_t *hash_lock = HDR_LOCK(hdr);
3684 mutex_enter(hash_lock);
3686 ASSERT3P(hdr, ==, buf->b_hdr);
3687 ASSERT3P(hdr->b_l1hdr.b_buf, !=, NULL);
3688 ASSERT3P(hash_lock, ==, HDR_LOCK(hdr));
3689 ASSERT3P(hdr->b_l1hdr.b_state, !=, arc_anon);
3690 ASSERT3P(buf->b_data, !=, NULL);
3692 arc_buf_destroy_impl(buf);
3693 (void) remove_reference(hdr, tag);
3694 mutex_exit(hash_lock);
3698 * Evict the arc_buf_hdr that is provided as a parameter. The resultant
3699 * state of the header is dependent on its state prior to entering this
3700 * function. The following transitions are possible:
3702 * - arc_mru -> arc_mru_ghost
3703 * - arc_mfu -> arc_mfu_ghost
3704 * - arc_mru_ghost -> arc_l2c_only
3705 * - arc_mru_ghost -> deleted
3706 * - arc_mfu_ghost -> arc_l2c_only
3707 * - arc_mfu_ghost -> deleted
3708 * - arc_uncached -> deleted
3710 * Return total size of evicted data buffers for eviction progress tracking.
3711 * When evicting from ghost states return logical buffer size to make eviction
3712 * progress at the same (or at least comparable) rate as from non-ghost states.
3714 * Return *real_evicted for actual ARC size reduction to wake up threads
3715 * waiting for it. For non-ghost states it includes size of evicted data
3716 * buffers (the headers are not freed there). For ghost states it includes
3717 * only the evicted headers size.
3720 arc_evict_hdr(arc_buf_hdr_t *hdr, uint64_t *real_evicted)
3722 arc_state_t *evicted_state, *state;
3723 int64_t bytes_evicted = 0;
3724 uint_t min_lifetime = HDR_PRESCIENT_PREFETCH(hdr) ?
3725 arc_min_prescient_prefetch_ms : arc_min_prefetch_ms;
3727 ASSERT(MUTEX_HELD(HDR_LOCK(hdr)));
3728 ASSERT(HDR_HAS_L1HDR(hdr));
3729 ASSERT(!HDR_IO_IN_PROGRESS(hdr));
3730 ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
3731 ASSERT0(zfs_refcount_count(&hdr->b_l1hdr.b_refcnt));
3734 state = hdr->b_l1hdr.b_state;
3735 if (GHOST_STATE(state)) {
3738 * l2arc_write_buffers() relies on a header's L1 portion
3739 * (i.e. its b_pabd field) during it's write phase.
3740 * Thus, we cannot push a header onto the arc_l2c_only
3741 * state (removing its L1 piece) until the header is
3742 * done being written to the l2arc.
3744 if (HDR_HAS_L2HDR(hdr) && HDR_L2_WRITING(hdr)) {
3745 ARCSTAT_BUMP(arcstat_evict_l2_skip);
3746 return (bytes_evicted);
3749 ARCSTAT_BUMP(arcstat_deleted);
3750 bytes_evicted += HDR_GET_LSIZE(hdr);
3752 DTRACE_PROBE1(arc__delete, arc_buf_hdr_t *, hdr);
3754 if (HDR_HAS_L2HDR(hdr)) {
3755 ASSERT(hdr->b_l1hdr.b_pabd == NULL);
3756 ASSERT(!HDR_HAS_RABD(hdr));
3758 * This buffer is cached on the 2nd Level ARC;
3759 * don't destroy the header.
3761 arc_change_state(arc_l2c_only, hdr);
3763 * dropping from L1+L2 cached to L2-only,
3764 * realloc to remove the L1 header.
3766 (void) arc_hdr_realloc(hdr, hdr_full_cache,
3768 *real_evicted += HDR_FULL_SIZE - HDR_L2ONLY_SIZE;
3770 arc_change_state(arc_anon, hdr);
3771 arc_hdr_destroy(hdr);
3772 *real_evicted += HDR_FULL_SIZE;
3774 return (bytes_evicted);
3777 ASSERT(state == arc_mru || state == arc_mfu || state == arc_uncached);
3778 evicted_state = (state == arc_uncached) ? arc_anon :
3779 ((state == arc_mru) ? arc_mru_ghost : arc_mfu_ghost);
3781 /* prefetch buffers have a minimum lifespan */
3782 if ((hdr->b_flags & (ARC_FLAG_PREFETCH | ARC_FLAG_INDIRECT)) &&
3783 ddi_get_lbolt() - hdr->b_l1hdr.b_arc_access <
3784 MSEC_TO_TICK(min_lifetime)) {
3785 ARCSTAT_BUMP(arcstat_evict_skip);
3786 return (bytes_evicted);
3789 if (HDR_HAS_L2HDR(hdr)) {
3790 ARCSTAT_INCR(arcstat_evict_l2_cached, HDR_GET_LSIZE(hdr));
3792 if (l2arc_write_eligible(hdr->b_spa, hdr)) {
3793 ARCSTAT_INCR(arcstat_evict_l2_eligible,
3794 HDR_GET_LSIZE(hdr));
3796 switch (state->arcs_state) {
3799 arcstat_evict_l2_eligible_mru,
3800 HDR_GET_LSIZE(hdr));
3804 arcstat_evict_l2_eligible_mfu,
3805 HDR_GET_LSIZE(hdr));
3811 ARCSTAT_INCR(arcstat_evict_l2_ineligible,
3812 HDR_GET_LSIZE(hdr));
3816 bytes_evicted += arc_hdr_size(hdr);
3817 *real_evicted += arc_hdr_size(hdr);
3820 * If this hdr is being evicted and has a compressed buffer then we
3821 * discard it here before we change states. This ensures that the
3822 * accounting is updated correctly in arc_free_data_impl().
3824 if (hdr->b_l1hdr.b_pabd != NULL)
3825 arc_hdr_free_abd(hdr, B_FALSE);
3827 if (HDR_HAS_RABD(hdr))
3828 arc_hdr_free_abd(hdr, B_TRUE);
3830 arc_change_state(evicted_state, hdr);
3831 DTRACE_PROBE1(arc__evict, arc_buf_hdr_t *, hdr);
3832 if (evicted_state == arc_anon) {
3833 arc_hdr_destroy(hdr);
3834 *real_evicted += HDR_FULL_SIZE;
3836 ASSERT(HDR_IN_HASH_TABLE(hdr));
3839 return (bytes_evicted);
3843 arc_set_need_free(void)
3845 ASSERT(MUTEX_HELD(&arc_evict_lock));
3846 int64_t remaining = arc_free_memory() - arc_sys_free / 2;
3847 arc_evict_waiter_t *aw = list_tail(&arc_evict_waiters);
3849 arc_need_free = MAX(-remaining, 0);
3852 MAX(-remaining, (int64_t)(aw->aew_count - arc_evict_count));
3857 arc_evict_state_impl(multilist_t *ml, int idx, arc_buf_hdr_t *marker,
3858 uint64_t spa, uint64_t bytes)
3860 multilist_sublist_t *mls;
3861 uint64_t bytes_evicted = 0, real_evicted = 0;
3863 kmutex_t *hash_lock;
3864 uint_t evict_count = zfs_arc_evict_batch_limit;
3866 ASSERT3P(marker, !=, NULL);
3868 mls = multilist_sublist_lock(ml, idx);
3870 for (hdr = multilist_sublist_prev(mls, marker); likely(hdr != NULL);
3871 hdr = multilist_sublist_prev(mls, marker)) {
3872 if ((evict_count == 0) || (bytes_evicted >= bytes))
3876 * To keep our iteration location, move the marker
3877 * forward. Since we're not holding hdr's hash lock, we
3878 * must be very careful and not remove 'hdr' from the
3879 * sublist. Otherwise, other consumers might mistake the
3880 * 'hdr' as not being on a sublist when they call the
3881 * multilist_link_active() function (they all rely on
3882 * the hash lock protecting concurrent insertions and
3883 * removals). multilist_sublist_move_forward() was
3884 * specifically implemented to ensure this is the case
3885 * (only 'marker' will be removed and re-inserted).
3887 multilist_sublist_move_forward(mls, marker);
3890 * The only case where the b_spa field should ever be
3891 * zero, is the marker headers inserted by
3892 * arc_evict_state(). It's possible for multiple threads
3893 * to be calling arc_evict_state() concurrently (e.g.
3894 * dsl_pool_close() and zio_inject_fault()), so we must
3895 * skip any markers we see from these other threads.
3897 if (hdr->b_spa == 0)
3900 /* we're only interested in evicting buffers of a certain spa */
3901 if (spa != 0 && hdr->b_spa != spa) {
3902 ARCSTAT_BUMP(arcstat_evict_skip);
3906 hash_lock = HDR_LOCK(hdr);
3909 * We aren't calling this function from any code path
3910 * that would already be holding a hash lock, so we're
3911 * asserting on this assumption to be defensive in case
3912 * this ever changes. Without this check, it would be
3913 * possible to incorrectly increment arcstat_mutex_miss
3914 * below (e.g. if the code changed such that we called
3915 * this function with a hash lock held).
3917 ASSERT(!MUTEX_HELD(hash_lock));
3919 if (mutex_tryenter(hash_lock)) {
3921 uint64_t evicted = arc_evict_hdr(hdr, &revicted);
3922 mutex_exit(hash_lock);
3924 bytes_evicted += evicted;
3925 real_evicted += revicted;
3928 * If evicted is zero, arc_evict_hdr() must have
3929 * decided to skip this header, don't increment
3930 * evict_count in this case.
3936 ARCSTAT_BUMP(arcstat_mutex_miss);
3940 multilist_sublist_unlock(mls);
3943 * Increment the count of evicted bytes, and wake up any threads that
3944 * are waiting for the count to reach this value. Since the list is
3945 * ordered by ascending aew_count, we pop off the beginning of the
3946 * list until we reach the end, or a waiter that's past the current
3947 * "count". Doing this outside the loop reduces the number of times
3948 * we need to acquire the global arc_evict_lock.
3950 * Only wake when there's sufficient free memory in the system
3951 * (specifically, arc_sys_free/2, which by default is a bit more than
3952 * 1/64th of RAM). See the comments in arc_wait_for_eviction().
3954 mutex_enter(&arc_evict_lock);
3955 arc_evict_count += real_evicted;
3957 if (arc_free_memory() > arc_sys_free / 2) {
3958 arc_evict_waiter_t *aw;
3959 while ((aw = list_head(&arc_evict_waiters)) != NULL &&
3960 aw->aew_count <= arc_evict_count) {
3961 list_remove(&arc_evict_waiters, aw);
3962 cv_broadcast(&aw->aew_cv);
3965 arc_set_need_free();
3966 mutex_exit(&arc_evict_lock);
3969 * If the ARC size is reduced from arc_c_max to arc_c_min (especially
3970 * if the average cached block is small), eviction can be on-CPU for
3971 * many seconds. To ensure that other threads that may be bound to
3972 * this CPU are able to make progress, make a voluntary preemption
3975 kpreempt(KPREEMPT_SYNC);
3977 return (bytes_evicted);
3981 * Allocate an array of buffer headers used as placeholders during arc state
3984 static arc_buf_hdr_t **
3985 arc_state_alloc_markers(int count)
3987 arc_buf_hdr_t **markers;
3989 markers = kmem_zalloc(sizeof (*markers) * count, KM_SLEEP);
3990 for (int i = 0; i < count; i++) {
3991 markers[i] = kmem_cache_alloc(hdr_full_cache, KM_SLEEP);
3994 * A b_spa of 0 is used to indicate that this header is
3995 * a marker. This fact is used in arc_evict_state_impl().
3997 markers[i]->b_spa = 0;
4004 arc_state_free_markers(arc_buf_hdr_t **markers, int count)
4006 for (int i = 0; i < count; i++)
4007 kmem_cache_free(hdr_full_cache, markers[i]);
4008 kmem_free(markers, sizeof (*markers) * count);
4012 * Evict buffers from the given arc state, until we've removed the
4013 * specified number of bytes. Move the removed buffers to the
4014 * appropriate evict state.
4016 * This function makes a "best effort". It skips over any buffers
4017 * it can't get a hash_lock on, and so, may not catch all candidates.
4018 * It may also return without evicting as much space as requested.
4020 * If bytes is specified using the special value ARC_EVICT_ALL, this
4021 * will evict all available (i.e. unlocked and evictable) buffers from
4022 * the given arc state; which is used by arc_flush().
4025 arc_evict_state(arc_state_t *state, arc_buf_contents_t type, uint64_t spa,
4028 uint64_t total_evicted = 0;
4029 multilist_t *ml = &state->arcs_list[type];
4031 arc_buf_hdr_t **markers;
4033 num_sublists = multilist_get_num_sublists(ml);
4036 * If we've tried to evict from each sublist, made some
4037 * progress, but still have not hit the target number of bytes
4038 * to evict, we want to keep trying. The markers allow us to
4039 * pick up where we left off for each individual sublist, rather
4040 * than starting from the tail each time.
4042 if (zthr_iscurthread(arc_evict_zthr)) {
4043 markers = arc_state_evict_markers;
4044 ASSERT3S(num_sublists, <=, arc_state_evict_marker_count);
4046 markers = arc_state_alloc_markers(num_sublists);
4048 for (int i = 0; i < num_sublists; i++) {
4049 multilist_sublist_t *mls;
4051 mls = multilist_sublist_lock(ml, i);
4052 multilist_sublist_insert_tail(mls, markers[i]);
4053 multilist_sublist_unlock(mls);
4057 * While we haven't hit our target number of bytes to evict, or
4058 * we're evicting all available buffers.
4060 while (total_evicted < bytes) {
4061 int sublist_idx = multilist_get_random_index(ml);
4062 uint64_t scan_evicted = 0;
4065 * Start eviction using a randomly selected sublist,
4066 * this is to try and evenly balance eviction across all
4067 * sublists. Always starting at the same sublist
4068 * (e.g. index 0) would cause evictions to favor certain
4069 * sublists over others.
4071 for (int i = 0; i < num_sublists; i++) {
4072 uint64_t bytes_remaining;
4073 uint64_t bytes_evicted;
4075 if (total_evicted < bytes)
4076 bytes_remaining = bytes - total_evicted;
4080 bytes_evicted = arc_evict_state_impl(ml, sublist_idx,
4081 markers[sublist_idx], spa, bytes_remaining);
4083 scan_evicted += bytes_evicted;
4084 total_evicted += bytes_evicted;
4086 /* we've reached the end, wrap to the beginning */
4087 if (++sublist_idx >= num_sublists)
4092 * If we didn't evict anything during this scan, we have
4093 * no reason to believe we'll evict more during another
4094 * scan, so break the loop.
4096 if (scan_evicted == 0) {
4097 /* This isn't possible, let's make that obvious */
4098 ASSERT3S(bytes, !=, 0);
4101 * When bytes is ARC_EVICT_ALL, the only way to
4102 * break the loop is when scan_evicted is zero.
4103 * In that case, we actually have evicted enough,
4104 * so we don't want to increment the kstat.
4106 if (bytes != ARC_EVICT_ALL) {
4107 ASSERT3S(total_evicted, <, bytes);
4108 ARCSTAT_BUMP(arcstat_evict_not_enough);
4115 for (int i = 0; i < num_sublists; i++) {
4116 multilist_sublist_t *mls = multilist_sublist_lock(ml, i);
4117 multilist_sublist_remove(mls, markers[i]);
4118 multilist_sublist_unlock(mls);
4120 if (markers != arc_state_evict_markers)
4121 arc_state_free_markers(markers, num_sublists);
4123 return (total_evicted);
4127 * Flush all "evictable" data of the given type from the arc state
4128 * specified. This will not evict any "active" buffers (i.e. referenced).
4130 * When 'retry' is set to B_FALSE, the function will make a single pass
4131 * over the state and evict any buffers that it can. Since it doesn't
4132 * continually retry the eviction, it might end up leaving some buffers
4133 * in the ARC due to lock misses.
4135 * When 'retry' is set to B_TRUE, the function will continually retry the
4136 * eviction until *all* evictable buffers have been removed from the
4137 * state. As a result, if concurrent insertions into the state are
4138 * allowed (e.g. if the ARC isn't shutting down), this function might
4139 * wind up in an infinite loop, continually trying to evict buffers.
4142 arc_flush_state(arc_state_t *state, uint64_t spa, arc_buf_contents_t type,
4145 uint64_t evicted = 0;
4147 while (zfs_refcount_count(&state->arcs_esize[type]) != 0) {
4148 evicted += arc_evict_state(state, type, spa, ARC_EVICT_ALL);
4158 * Evict the specified number of bytes from the state specified. This
4159 * function prevents us from trying to evict more from a state's list
4160 * than is "evictable", and to skip evicting altogether when passed a
4161 * negative value for "bytes". In contrast, arc_evict_state() will
4162 * evict everything it can, when passed a negative value for "bytes".
4165 arc_evict_impl(arc_state_t *state, arc_buf_contents_t type, int64_t bytes)
4169 if (bytes > 0 && zfs_refcount_count(&state->arcs_esize[type]) > 0) {
4170 delta = MIN(zfs_refcount_count(&state->arcs_esize[type]),
4172 return (arc_evict_state(state, type, 0, delta));
4179 * Adjust specified fraction, taking into account initial ghost state(s) size,
4180 * ghost hit bytes towards increasing the fraction, ghost hit bytes towards
4181 * decreasing it, plus a balance factor, controlling the decrease rate, used
4182 * to balance metadata vs data.
4185 arc_evict_adj(uint64_t frac, uint64_t total, uint64_t up, uint64_t down,
4188 if (total < 8 || up + down == 0)
4192 * We should not have more ghost hits than ghost size, but they
4193 * may get close. Restrict maximum adjustment in that case.
4195 if (up + down >= total / 4) {
4196 uint64_t scale = (up + down) / (total / 8);
4201 /* Get maximal dynamic range by choosing optimal shifts. */
4202 int s = highbit64(total);
4203 s = MIN(64 - s, 32);
4205 uint64_t ofrac = (1ULL << 32) - frac;
4207 if (frac >= 4 * ofrac)
4208 up /= frac / (2 * ofrac + 1);
4209 up = (up << s) / (total >> (32 - s));
4210 if (ofrac >= 4 * frac)
4211 down /= ofrac / (2 * frac + 1);
4212 down = (down << s) / (total >> (32 - s));
4213 down = down * 100 / balance;
4215 return (frac + up - down);
4219 * Evict buffers from the cache, such that arcstat_size is capped by arc_c.
4224 uint64_t asize, bytes, total_evicted = 0;
4225 int64_t e, mrud, mrum, mfud, mfum, w;
4226 static uint64_t ogrd, ogrm, ogfd, ogfm;
4227 static uint64_t gsrd, gsrm, gsfd, gsfm;
4228 uint64_t ngrd, ngrm, ngfd, ngfm;
4230 /* Get current size of ARC states we can evict from. */
4231 mrud = zfs_refcount_count(&arc_mru->arcs_size[ARC_BUFC_DATA]) +
4232 zfs_refcount_count(&arc_anon->arcs_size[ARC_BUFC_DATA]);
4233 mrum = zfs_refcount_count(&arc_mru->arcs_size[ARC_BUFC_METADATA]) +
4234 zfs_refcount_count(&arc_anon->arcs_size[ARC_BUFC_METADATA]);
4235 mfud = zfs_refcount_count(&arc_mfu->arcs_size[ARC_BUFC_DATA]);
4236 mfum = zfs_refcount_count(&arc_mfu->arcs_size[ARC_BUFC_METADATA]);
4237 uint64_t d = mrud + mfud;
4238 uint64_t m = mrum + mfum;
4241 /* Get ARC ghost hits since last eviction. */
4242 ngrd = wmsum_value(&arc_mru_ghost->arcs_hits[ARC_BUFC_DATA]);
4243 uint64_t grd = ngrd - ogrd;
4245 ngrm = wmsum_value(&arc_mru_ghost->arcs_hits[ARC_BUFC_METADATA]);
4246 uint64_t grm = ngrm - ogrm;
4248 ngfd = wmsum_value(&arc_mfu_ghost->arcs_hits[ARC_BUFC_DATA]);
4249 uint64_t gfd = ngfd - ogfd;
4251 ngfm = wmsum_value(&arc_mfu_ghost->arcs_hits[ARC_BUFC_METADATA]);
4252 uint64_t gfm = ngfm - ogfm;
4255 /* Adjust ARC states balance based on ghost hits. */
4256 arc_meta = arc_evict_adj(arc_meta, gsrd + gsrm + gsfd + gsfm,
4257 grm + gfm, grd + gfd, zfs_arc_meta_balance);
4258 arc_pd = arc_evict_adj(arc_pd, gsrd + gsfd, grd, gfd, 100);
4259 arc_pm = arc_evict_adj(arc_pm, gsrm + gsfm, grm, gfm, 100);
4261 asize = aggsum_value(&arc_sums.arcstat_size);
4262 int64_t wt = t - (asize - arc_c);
4265 * Try to reduce pinned dnodes if more than 3/4 of wanted metadata
4266 * target is not evictable or if they go over arc_dnode_limit.
4269 int64_t dn = wmsum_value(&arc_sums.arcstat_dnode_size);
4270 w = wt * (int64_t)(arc_meta >> 16) >> 16;
4271 if (zfs_refcount_count(&arc_mru->arcs_size[ARC_BUFC_METADATA]) +
4272 zfs_refcount_count(&arc_mfu->arcs_size[ARC_BUFC_METADATA]) -
4273 zfs_refcount_count(&arc_mru->arcs_esize[ARC_BUFC_METADATA]) -
4274 zfs_refcount_count(&arc_mfu->arcs_esize[ARC_BUFC_METADATA]) >
4276 prune = dn / sizeof (dnode_t) *
4277 zfs_arc_dnode_reduce_percent / 100;
4278 } else if (dn > arc_dnode_limit) {
4279 prune = (dn - arc_dnode_limit) / sizeof (dnode_t) *
4280 zfs_arc_dnode_reduce_percent / 100;
4283 arc_prune_async(prune);
4285 /* Evict MRU metadata. */
4286 w = wt * (int64_t)(arc_meta * arc_pm >> 48) >> 16;
4287 e = MIN((int64_t)(asize - arc_c), (int64_t)(mrum - w));
4288 bytes = arc_evict_impl(arc_mru, ARC_BUFC_METADATA, e);
4289 total_evicted += bytes;
4293 /* Evict MFU metadata. */
4294 w = wt * (int64_t)(arc_meta >> 16) >> 16;
4295 e = MIN((int64_t)(asize - arc_c), (int64_t)(m - w));
4296 bytes = arc_evict_impl(arc_mfu, ARC_BUFC_METADATA, e);
4297 total_evicted += bytes;
4301 /* Evict MRU data. */
4302 wt -= m - total_evicted;
4303 w = wt * (int64_t)(arc_pd >> 16) >> 16;
4304 e = MIN((int64_t)(asize - arc_c), (int64_t)(mrud - w));
4305 bytes = arc_evict_impl(arc_mru, ARC_BUFC_DATA, e);
4306 total_evicted += bytes;
4310 /* Evict MFU data. */
4312 bytes = arc_evict_impl(arc_mfu, ARC_BUFC_DATA, e);
4314 total_evicted += bytes;
4319 * Size of each state's ghost list represents how much that state
4320 * may grow by shrinking the other states. Would it need to shrink
4321 * other states to zero (that is unlikely), its ghost size would be
4322 * equal to sum of other three state sizes. But excessive ghost
4323 * size may result in false ghost hits (too far back), that may
4324 * never result in real cache hits if several states are competing.
4325 * So choose some arbitraty point of 1/2 of other state sizes.
4327 gsrd = (mrum + mfud + mfum) / 2;
4328 e = zfs_refcount_count(&arc_mru_ghost->arcs_size[ARC_BUFC_DATA]) -
4330 (void) arc_evict_impl(arc_mru_ghost, ARC_BUFC_DATA, e);
4332 gsrm = (mrud + mfud + mfum) / 2;
4333 e = zfs_refcount_count(&arc_mru_ghost->arcs_size[ARC_BUFC_METADATA]) -
4335 (void) arc_evict_impl(arc_mru_ghost, ARC_BUFC_METADATA, e);
4337 gsfd = (mrud + mrum + mfum) / 2;
4338 e = zfs_refcount_count(&arc_mfu_ghost->arcs_size[ARC_BUFC_DATA]) -
4340 (void) arc_evict_impl(arc_mfu_ghost, ARC_BUFC_DATA, e);
4342 gsfm = (mrud + mrum + mfud) / 2;
4343 e = zfs_refcount_count(&arc_mfu_ghost->arcs_size[ARC_BUFC_METADATA]) -
4345 (void) arc_evict_impl(arc_mfu_ghost, ARC_BUFC_METADATA, e);
4347 return (total_evicted);
4351 arc_flush(spa_t *spa, boolean_t retry)
4356 * If retry is B_TRUE, a spa must not be specified since we have
4357 * no good way to determine if all of a spa's buffers have been
4358 * evicted from an arc state.
4360 ASSERT(!retry || spa == NULL);
4363 guid = spa_load_guid(spa);
4365 (void) arc_flush_state(arc_mru, guid, ARC_BUFC_DATA, retry);
4366 (void) arc_flush_state(arc_mru, guid, ARC_BUFC_METADATA, retry);
4368 (void) arc_flush_state(arc_mfu, guid, ARC_BUFC_DATA, retry);
4369 (void) arc_flush_state(arc_mfu, guid, ARC_BUFC_METADATA, retry);
4371 (void) arc_flush_state(arc_mru_ghost, guid, ARC_BUFC_DATA, retry);
4372 (void) arc_flush_state(arc_mru_ghost, guid, ARC_BUFC_METADATA, retry);
4374 (void) arc_flush_state(arc_mfu_ghost, guid, ARC_BUFC_DATA, retry);
4375 (void) arc_flush_state(arc_mfu_ghost, guid, ARC_BUFC_METADATA, retry);
4377 (void) arc_flush_state(arc_uncached, guid, ARC_BUFC_DATA, retry);
4378 (void) arc_flush_state(arc_uncached, guid, ARC_BUFC_METADATA, retry);
4382 arc_reduce_target_size(int64_t to_free)
4390 * All callers want the ARC to actually evict (at least) this much
4391 * memory. Therefore we reduce from the lower of the current size and
4392 * the target size. This way, even if arc_c is much higher than
4393 * arc_size (as can be the case after many calls to arc_freed(), we will
4394 * immediately have arc_c < arc_size and therefore the arc_evict_zthr
4397 uint64_t asize = aggsum_value(&arc_sums.arcstat_size);
4399 to_free += c - asize;
4400 arc_c = MAX((int64_t)c - to_free, (int64_t)arc_c_min);
4402 /* See comment in arc_evict_cb_check() on why lock+flag */
4403 mutex_enter(&arc_evict_lock);
4404 arc_evict_needed = B_TRUE;
4405 mutex_exit(&arc_evict_lock);
4406 zthr_wakeup(arc_evict_zthr);
4410 * Determine if the system is under memory pressure and is asking
4411 * to reclaim memory. A return value of B_TRUE indicates that the system
4412 * is under memory pressure and that the arc should adjust accordingly.
4415 arc_reclaim_needed(void)
4417 return (arc_available_memory() < 0);
4421 arc_kmem_reap_soon(void)
4424 kmem_cache_t *prev_cache = NULL;
4425 kmem_cache_t *prev_data_cache = NULL;
4430 * Reclaim unused memory from all kmem caches.
4436 for (i = 0; i < SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT; i++) {
4438 /* reach upper limit of cache size on 32-bit */
4439 if (zio_buf_cache[i] == NULL)
4442 if (zio_buf_cache[i] != prev_cache) {
4443 prev_cache = zio_buf_cache[i];
4444 kmem_cache_reap_now(zio_buf_cache[i]);
4446 if (zio_data_buf_cache[i] != prev_data_cache) {
4447 prev_data_cache = zio_data_buf_cache[i];
4448 kmem_cache_reap_now(zio_data_buf_cache[i]);
4451 kmem_cache_reap_now(buf_cache);
4452 kmem_cache_reap_now(hdr_full_cache);
4453 kmem_cache_reap_now(hdr_l2only_cache);
4454 kmem_cache_reap_now(zfs_btree_leaf_cache);
4455 abd_cache_reap_now();
4459 arc_evict_cb_check(void *arg, zthr_t *zthr)
4461 (void) arg, (void) zthr;
4465 * This is necessary in order to keep the kstat information
4466 * up to date for tools that display kstat data such as the
4467 * mdb ::arc dcmd and the Linux crash utility. These tools
4468 * typically do not call kstat's update function, but simply
4469 * dump out stats from the most recent update. Without
4470 * this call, these commands may show stale stats for the
4471 * anon, mru, mru_ghost, mfu, and mfu_ghost lists. Even
4472 * with this call, the data might be out of date if the
4473 * evict thread hasn't been woken recently; but that should
4474 * suffice. The arc_state_t structures can be queried
4475 * directly if more accurate information is needed.
4477 if (arc_ksp != NULL)
4478 arc_ksp->ks_update(arc_ksp, KSTAT_READ);
4482 * We have to rely on arc_wait_for_eviction() to tell us when to
4483 * evict, rather than checking if we are overflowing here, so that we
4484 * are sure to not leave arc_wait_for_eviction() waiting on aew_cv.
4485 * If we have become "not overflowing" since arc_wait_for_eviction()
4486 * checked, we need to wake it up. We could broadcast the CV here,
4487 * but arc_wait_for_eviction() may have not yet gone to sleep. We
4488 * would need to use a mutex to ensure that this function doesn't
4489 * broadcast until arc_wait_for_eviction() has gone to sleep (e.g.
4490 * the arc_evict_lock). However, the lock ordering of such a lock
4491 * would necessarily be incorrect with respect to the zthr_lock,
4492 * which is held before this function is called, and is held by
4493 * arc_wait_for_eviction() when it calls zthr_wakeup().
4495 if (arc_evict_needed)
4499 * If we have buffers in uncached state, evict them periodically.
4501 return ((zfs_refcount_count(&arc_uncached->arcs_esize[ARC_BUFC_DATA]) +
4502 zfs_refcount_count(&arc_uncached->arcs_esize[ARC_BUFC_METADATA]) &&
4503 ddi_get_lbolt() - arc_last_uncached_flush >
4504 MSEC_TO_TICK(arc_min_prefetch_ms / 2)));
4508 * Keep arc_size under arc_c by running arc_evict which evicts data
4512 arc_evict_cb(void *arg, zthr_t *zthr)
4514 (void) arg, (void) zthr;
4516 uint64_t evicted = 0;
4517 fstrans_cookie_t cookie = spl_fstrans_mark();
4519 /* Always try to evict from uncached state. */
4520 arc_last_uncached_flush = ddi_get_lbolt();
4521 evicted += arc_flush_state(arc_uncached, 0, ARC_BUFC_DATA, B_FALSE);
4522 evicted += arc_flush_state(arc_uncached, 0, ARC_BUFC_METADATA, B_FALSE);
4524 /* Evict from other states only if told to. */
4525 if (arc_evict_needed)
4526 evicted += arc_evict();
4529 * If evicted is zero, we couldn't evict anything
4530 * via arc_evict(). This could be due to hash lock
4531 * collisions, but more likely due to the majority of
4532 * arc buffers being unevictable. Therefore, even if
4533 * arc_size is above arc_c, another pass is unlikely to
4534 * be helpful and could potentially cause us to enter an
4535 * infinite loop. Additionally, zthr_iscancelled() is
4536 * checked here so that if the arc is shutting down, the
4537 * broadcast will wake any remaining arc evict waiters.
4539 mutex_enter(&arc_evict_lock);
4540 arc_evict_needed = !zthr_iscancelled(arc_evict_zthr) &&
4541 evicted > 0 && aggsum_compare(&arc_sums.arcstat_size, arc_c) > 0;
4542 if (!arc_evict_needed) {
4544 * We're either no longer overflowing, or we
4545 * can't evict anything more, so we should wake
4546 * arc_get_data_impl() sooner.
4548 arc_evict_waiter_t *aw;
4549 while ((aw = list_remove_head(&arc_evict_waiters)) != NULL) {
4550 cv_broadcast(&aw->aew_cv);
4552 arc_set_need_free();
4554 mutex_exit(&arc_evict_lock);
4555 spl_fstrans_unmark(cookie);
4559 arc_reap_cb_check(void *arg, zthr_t *zthr)
4561 (void) arg, (void) zthr;
4563 int64_t free_memory = arc_available_memory();
4564 static int reap_cb_check_counter = 0;
4567 * If a kmem reap is already active, don't schedule more. We must
4568 * check for this because kmem_cache_reap_soon() won't actually
4569 * block on the cache being reaped (this is to prevent callers from
4570 * becoming implicitly blocked by a system-wide kmem reap -- which,
4571 * on a system with many, many full magazines, can take minutes).
4573 if (!kmem_cache_reap_active() && free_memory < 0) {
4575 arc_no_grow = B_TRUE;
4578 * Wait at least zfs_grow_retry (default 5) seconds
4579 * before considering growing.
4581 arc_growtime = gethrtime() + SEC2NSEC(arc_grow_retry);
4583 } else if (free_memory < arc_c >> arc_no_grow_shift) {
4584 arc_no_grow = B_TRUE;
4585 } else if (gethrtime() >= arc_growtime) {
4586 arc_no_grow = B_FALSE;
4590 * Called unconditionally every 60 seconds to reclaim unused
4591 * zstd compression and decompression context. This is done
4592 * here to avoid the need for an independent thread.
4594 if (!((reap_cb_check_counter++) % 60))
4595 zfs_zstd_cache_reap_now();
4601 * Keep enough free memory in the system by reaping the ARC's kmem
4602 * caches. To cause more slabs to be reapable, we may reduce the
4603 * target size of the cache (arc_c), causing the arc_evict_cb()
4604 * to free more buffers.
4607 arc_reap_cb(void *arg, zthr_t *zthr)
4609 (void) arg, (void) zthr;
4611 int64_t free_memory;
4612 fstrans_cookie_t cookie = spl_fstrans_mark();
4615 * Kick off asynchronous kmem_reap()'s of all our caches.
4617 arc_kmem_reap_soon();
4620 * Wait at least arc_kmem_cache_reap_retry_ms between
4621 * arc_kmem_reap_soon() calls. Without this check it is possible to
4622 * end up in a situation where we spend lots of time reaping
4623 * caches, while we're near arc_c_min. Waiting here also gives the
4624 * subsequent free memory check a chance of finding that the
4625 * asynchronous reap has already freed enough memory, and we don't
4626 * need to call arc_reduce_target_size().
4628 delay((hz * arc_kmem_cache_reap_retry_ms + 999) / 1000);
4631 * Reduce the target size as needed to maintain the amount of free
4632 * memory in the system at a fraction of the arc_size (1/128th by
4633 * default). If oversubscribed (free_memory < 0) then reduce the
4634 * target arc_size by the deficit amount plus the fractional
4635 * amount. If free memory is positive but less than the fractional
4636 * amount, reduce by what is needed to hit the fractional amount.
4638 free_memory = arc_available_memory();
4640 int64_t can_free = arc_c - arc_c_min;
4642 int64_t to_free = (can_free >> arc_shrink_shift) - free_memory;
4644 arc_reduce_target_size(to_free);
4646 spl_fstrans_unmark(cookie);
4651 * Determine the amount of memory eligible for eviction contained in the
4652 * ARC. All clean data reported by the ghost lists can always be safely
4653 * evicted. Due to arc_c_min, the same does not hold for all clean data
4654 * contained by the regular mru and mfu lists.
4656 * In the case of the regular mru and mfu lists, we need to report as
4657 * much clean data as possible, such that evicting that same reported
4658 * data will not bring arc_size below arc_c_min. Thus, in certain
4659 * circumstances, the total amount of clean data in the mru and mfu
4660 * lists might not actually be evictable.
4662 * The following two distinct cases are accounted for:
4664 * 1. The sum of the amount of dirty data contained by both the mru and
4665 * mfu lists, plus the ARC's other accounting (e.g. the anon list),
4666 * is greater than or equal to arc_c_min.
4667 * (i.e. amount of dirty data >= arc_c_min)
4669 * This is the easy case; all clean data contained by the mru and mfu
4670 * lists is evictable. Evicting all clean data can only drop arc_size
4671 * to the amount of dirty data, which is greater than arc_c_min.
4673 * 2. The sum of the amount of dirty data contained by both the mru and
4674 * mfu lists, plus the ARC's other accounting (e.g. the anon list),
4675 * is less than arc_c_min.
4676 * (i.e. arc_c_min > amount of dirty data)
4678 * 2.1. arc_size is greater than or equal arc_c_min.
4679 * (i.e. arc_size >= arc_c_min > amount of dirty data)
4681 * In this case, not all clean data from the regular mru and mfu
4682 * lists is actually evictable; we must leave enough clean data
4683 * to keep arc_size above arc_c_min. Thus, the maximum amount of
4684 * evictable data from the two lists combined, is exactly the
4685 * difference between arc_size and arc_c_min.
4687 * 2.2. arc_size is less than arc_c_min
4688 * (i.e. arc_c_min > arc_size > amount of dirty data)
4690 * In this case, none of the data contained in the mru and mfu
4691 * lists is evictable, even if it's clean. Since arc_size is
4692 * already below arc_c_min, evicting any more would only
4693 * increase this negative difference.
4696 #endif /* _KERNEL */
4699 * Adapt arc info given the number of bytes we are trying to add and
4700 * the state that we are coming from. This function is only called
4701 * when we are adding new content to the cache.
4704 arc_adapt(uint64_t bytes)
4707 * Wake reap thread if we do not have any available memory
4709 if (arc_reclaim_needed()) {
4710 zthr_wakeup(arc_reap_zthr);
4717 if (arc_c >= arc_c_max)
4721 * If we're within (2 * maxblocksize) bytes of the target
4722 * cache size, increment the target cache size
4724 if (aggsum_upper_bound(&arc_sums.arcstat_size) +
4725 2 * SPA_MAXBLOCKSIZE >= arc_c) {
4726 uint64_t dc = MAX(bytes, SPA_OLD_MAXBLOCKSIZE);
4727 if (atomic_add_64_nv(&arc_c, dc) > arc_c_max)
4733 * Check if arc_size has grown past our upper threshold, determined by
4734 * zfs_arc_overflow_shift.
4736 static arc_ovf_level_t
4737 arc_is_overflowing(boolean_t use_reserve)
4739 /* Always allow at least one block of overflow */
4740 int64_t overflow = MAX(SPA_MAXBLOCKSIZE,
4741 arc_c >> zfs_arc_overflow_shift);
4744 * We just compare the lower bound here for performance reasons. Our
4745 * primary goals are to make sure that the arc never grows without
4746 * bound, and that it can reach its maximum size. This check
4747 * accomplishes both goals. The maximum amount we could run over by is
4748 * 2 * aggsum_borrow_multiplier * NUM_CPUS * the average size of a block
4749 * in the ARC. In practice, that's in the tens of MB, which is low
4750 * enough to be safe.
4752 int64_t over = aggsum_lower_bound(&arc_sums.arcstat_size) -
4753 arc_c - overflow / 2;
4756 return (over < 0 ? ARC_OVF_NONE :
4757 over < overflow ? ARC_OVF_SOME : ARC_OVF_SEVERE);
4761 arc_get_data_abd(arc_buf_hdr_t *hdr, uint64_t size, const void *tag,
4764 arc_buf_contents_t type = arc_buf_type(hdr);
4766 arc_get_data_impl(hdr, size, tag, alloc_flags);
4767 if (alloc_flags & ARC_HDR_ALLOC_LINEAR)
4768 return (abd_alloc_linear(size, type == ARC_BUFC_METADATA));
4770 return (abd_alloc(size, type == ARC_BUFC_METADATA));
4774 arc_get_data_buf(arc_buf_hdr_t *hdr, uint64_t size, const void *tag)
4776 arc_buf_contents_t type = arc_buf_type(hdr);
4778 arc_get_data_impl(hdr, size, tag, 0);
4779 if (type == ARC_BUFC_METADATA) {
4780 return (zio_buf_alloc(size));
4782 ASSERT(type == ARC_BUFC_DATA);
4783 return (zio_data_buf_alloc(size));
4788 * Wait for the specified amount of data (in bytes) to be evicted from the
4789 * ARC, and for there to be sufficient free memory in the system. Waiting for
4790 * eviction ensures that the memory used by the ARC decreases. Waiting for
4791 * free memory ensures that the system won't run out of free pages, regardless
4792 * of ARC behavior and settings. See arc_lowmem_init().
4795 arc_wait_for_eviction(uint64_t amount, boolean_t use_reserve)
4797 switch (arc_is_overflowing(use_reserve)) {
4802 * This is a bit racy without taking arc_evict_lock, but the
4803 * worst that can happen is we either call zthr_wakeup() extra
4804 * time due to race with other thread here, or the set flag
4805 * get cleared by arc_evict_cb(), which is unlikely due to
4806 * big hysteresis, but also not important since at this level
4807 * of overflow the eviction is purely advisory. Same time
4808 * taking the global lock here every time without waiting for
4809 * the actual eviction creates a significant lock contention.
4811 if (!arc_evict_needed) {
4812 arc_evict_needed = B_TRUE;
4813 zthr_wakeup(arc_evict_zthr);
4816 case ARC_OVF_SEVERE:
4819 arc_evict_waiter_t aw;
4820 list_link_init(&aw.aew_node);
4821 cv_init(&aw.aew_cv, NULL, CV_DEFAULT, NULL);
4823 uint64_t last_count = 0;
4824 mutex_enter(&arc_evict_lock);
4825 if (!list_is_empty(&arc_evict_waiters)) {
4826 arc_evict_waiter_t *last =
4827 list_tail(&arc_evict_waiters);
4828 last_count = last->aew_count;
4829 } else if (!arc_evict_needed) {
4830 arc_evict_needed = B_TRUE;
4831 zthr_wakeup(arc_evict_zthr);
4834 * Note, the last waiter's count may be less than
4835 * arc_evict_count if we are low on memory in which
4836 * case arc_evict_state_impl() may have deferred
4837 * wakeups (but still incremented arc_evict_count).
4839 aw.aew_count = MAX(last_count, arc_evict_count) + amount;
4841 list_insert_tail(&arc_evict_waiters, &aw);
4843 arc_set_need_free();
4845 DTRACE_PROBE3(arc__wait__for__eviction,
4847 uint64_t, arc_evict_count,
4848 uint64_t, aw.aew_count);
4851 * We will be woken up either when arc_evict_count reaches
4852 * aew_count, or when the ARC is no longer overflowing and
4853 * eviction completes.
4854 * In case of "false" wakeup, we will still be on the list.
4857 cv_wait(&aw.aew_cv, &arc_evict_lock);
4858 } while (list_link_active(&aw.aew_node));
4859 mutex_exit(&arc_evict_lock);
4861 cv_destroy(&aw.aew_cv);
4867 * Allocate a block and return it to the caller. If we are hitting the
4868 * hard limit for the cache size, we must sleep, waiting for the eviction
4869 * thread to catch up. If we're past the target size but below the hard
4870 * limit, we'll only signal the reclaim thread and continue on.
4873 arc_get_data_impl(arc_buf_hdr_t *hdr, uint64_t size, const void *tag,
4879 * If arc_size is currently overflowing, we must be adding data
4880 * faster than we are evicting. To ensure we don't compound the
4881 * problem by adding more data and forcing arc_size to grow even
4882 * further past it's target size, we wait for the eviction thread to
4883 * make some progress. We also wait for there to be sufficient free
4884 * memory in the system, as measured by arc_free_memory().
4886 * Specifically, we wait for zfs_arc_eviction_pct percent of the
4887 * requested size to be evicted. This should be more than 100%, to
4888 * ensure that that progress is also made towards getting arc_size
4889 * under arc_c. See the comment above zfs_arc_eviction_pct.
4891 arc_wait_for_eviction(size * zfs_arc_eviction_pct / 100,
4892 alloc_flags & ARC_HDR_USE_RESERVE);
4894 arc_buf_contents_t type = arc_buf_type(hdr);
4895 if (type == ARC_BUFC_METADATA) {
4896 arc_space_consume(size, ARC_SPACE_META);
4898 arc_space_consume(size, ARC_SPACE_DATA);
4902 * Update the state size. Note that ghost states have a
4903 * "ghost size" and so don't need to be updated.
4905 arc_state_t *state = hdr->b_l1hdr.b_state;
4906 if (!GHOST_STATE(state)) {
4908 (void) zfs_refcount_add_many(&state->arcs_size[type], size,
4912 * If this is reached via arc_read, the link is
4913 * protected by the hash lock. If reached via
4914 * arc_buf_alloc, the header should not be accessed by
4915 * any other thread. And, if reached via arc_read_done,
4916 * the hash lock will protect it if it's found in the
4917 * hash table; otherwise no other thread should be
4918 * trying to [add|remove]_reference it.
4920 if (multilist_link_active(&hdr->b_l1hdr.b_arc_node)) {
4921 ASSERT(zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
4922 (void) zfs_refcount_add_many(&state->arcs_esize[type],
4929 arc_free_data_abd(arc_buf_hdr_t *hdr, abd_t *abd, uint64_t size,
4932 arc_free_data_impl(hdr, size, tag);
4937 arc_free_data_buf(arc_buf_hdr_t *hdr, void *buf, uint64_t size, const void *tag)
4939 arc_buf_contents_t type = arc_buf_type(hdr);
4941 arc_free_data_impl(hdr, size, tag);
4942 if (type == ARC_BUFC_METADATA) {
4943 zio_buf_free(buf, size);
4945 ASSERT(type == ARC_BUFC_DATA);
4946 zio_data_buf_free(buf, size);
4951 * Free the arc data buffer.
4954 arc_free_data_impl(arc_buf_hdr_t *hdr, uint64_t size, const void *tag)
4956 arc_state_t *state = hdr->b_l1hdr.b_state;
4957 arc_buf_contents_t type = arc_buf_type(hdr);
4959 /* protected by hash lock, if in the hash table */
4960 if (multilist_link_active(&hdr->b_l1hdr.b_arc_node)) {
4961 ASSERT(zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt));
4962 ASSERT(state != arc_anon && state != arc_l2c_only);
4964 (void) zfs_refcount_remove_many(&state->arcs_esize[type],
4967 (void) zfs_refcount_remove_many(&state->arcs_size[type], size, tag);
4969 VERIFY3U(hdr->b_type, ==, type);
4970 if (type == ARC_BUFC_METADATA) {
4971 arc_space_return(size, ARC_SPACE_META);
4973 ASSERT(type == ARC_BUFC_DATA);
4974 arc_space_return(size, ARC_SPACE_DATA);
4979 * This routine is called whenever a buffer is accessed.
4982 arc_access(arc_buf_hdr_t *hdr, arc_flags_t arc_flags, boolean_t hit)
4984 ASSERT(MUTEX_HELD(HDR_LOCK(hdr)));
4985 ASSERT(HDR_HAS_L1HDR(hdr));
4988 * Update buffer prefetch status.
4990 boolean_t was_prefetch = HDR_PREFETCH(hdr);
4991 boolean_t now_prefetch = arc_flags & ARC_FLAG_PREFETCH;
4992 if (was_prefetch != now_prefetch) {
4994 ARCSTAT_CONDSTAT(hit, demand_hit, demand_iohit,
4995 HDR_PRESCIENT_PREFETCH(hdr), prescient, predictive,
4998 if (HDR_HAS_L2HDR(hdr))
4999 l2arc_hdr_arcstats_decrement_state(hdr);
5001 arc_hdr_clear_flags(hdr,
5002 ARC_FLAG_PREFETCH | ARC_FLAG_PRESCIENT_PREFETCH);
5004 arc_hdr_set_flags(hdr, ARC_FLAG_PREFETCH);
5006 if (HDR_HAS_L2HDR(hdr))
5007 l2arc_hdr_arcstats_increment_state(hdr);
5010 if (arc_flags & ARC_FLAG_PRESCIENT_PREFETCH) {
5011 arc_hdr_set_flags(hdr, ARC_FLAG_PRESCIENT_PREFETCH);
5012 ARCSTAT_BUMP(arcstat_prescient_prefetch);
5014 ARCSTAT_BUMP(arcstat_predictive_prefetch);
5017 if (arc_flags & ARC_FLAG_L2CACHE)
5018 arc_hdr_set_flags(hdr, ARC_FLAG_L2CACHE);
5020 clock_t now = ddi_get_lbolt();
5021 if (hdr->b_l1hdr.b_state == arc_anon) {
5022 arc_state_t *new_state;
5024 * This buffer is not in the cache, and does not appear in
5025 * our "ghost" lists. Add it to the MRU or uncached state.
5027 ASSERT0(hdr->b_l1hdr.b_arc_access);
5028 hdr->b_l1hdr.b_arc_access = now;
5029 if (HDR_UNCACHED(hdr)) {
5030 new_state = arc_uncached;
5031 DTRACE_PROBE1(new_state__uncached, arc_buf_hdr_t *,
5034 new_state = arc_mru;
5035 DTRACE_PROBE1(new_state__mru, arc_buf_hdr_t *, hdr);
5037 arc_change_state(new_state, hdr);
5038 } else if (hdr->b_l1hdr.b_state == arc_mru) {
5040 * This buffer has been accessed once recently and either
5041 * its read is still in progress or it is in the cache.
5043 if (HDR_IO_IN_PROGRESS(hdr)) {
5044 hdr->b_l1hdr.b_arc_access = now;
5047 hdr->b_l1hdr.b_mru_hits++;
5048 ARCSTAT_BUMP(arcstat_mru_hits);
5051 * If the previous access was a prefetch, then it already
5052 * handled possible promotion, so nothing more to do for now.
5055 hdr->b_l1hdr.b_arc_access = now;
5060 * If more than ARC_MINTIME have passed from the previous
5061 * hit, promote the buffer to the MFU state.
5063 if (ddi_time_after(now, hdr->b_l1hdr.b_arc_access +
5065 hdr->b_l1hdr.b_arc_access = now;
5066 DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, hdr);
5067 arc_change_state(arc_mfu, hdr);
5069 } else if (hdr->b_l1hdr.b_state == arc_mru_ghost) {
5070 arc_state_t *new_state;
5072 * This buffer has been accessed once recently, but was
5073 * evicted from the cache. Would we have bigger MRU, it
5074 * would be an MRU hit, so handle it the same way, except
5075 * we don't need to check the previous access time.
5077 hdr->b_l1hdr.b_mru_ghost_hits++;
5078 ARCSTAT_BUMP(arcstat_mru_ghost_hits);
5079 hdr->b_l1hdr.b_arc_access = now;
5080 wmsum_add(&arc_mru_ghost->arcs_hits[arc_buf_type(hdr)],
5083 new_state = arc_mru;
5084 DTRACE_PROBE1(new_state__mru, arc_buf_hdr_t *, hdr);
5086 new_state = arc_mfu;
5087 DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, hdr);
5089 arc_change_state(new_state, hdr);
5090 } else if (hdr->b_l1hdr.b_state == arc_mfu) {
5092 * This buffer has been accessed more than once and either
5093 * still in the cache or being restored from one of ghosts.
5095 if (!HDR_IO_IN_PROGRESS(hdr)) {
5096 hdr->b_l1hdr.b_mfu_hits++;
5097 ARCSTAT_BUMP(arcstat_mfu_hits);
5099 hdr->b_l1hdr.b_arc_access = now;
5100 } else if (hdr->b_l1hdr.b_state == arc_mfu_ghost) {
5102 * This buffer has been accessed more than once recently, but
5103 * has been evicted from the cache. Would we have bigger MFU
5104 * it would stay in cache, so move it back to MFU state.
5106 hdr->b_l1hdr.b_mfu_ghost_hits++;
5107 ARCSTAT_BUMP(arcstat_mfu_ghost_hits);
5108 hdr->b_l1hdr.b_arc_access = now;
5109 wmsum_add(&arc_mfu_ghost->arcs_hits[arc_buf_type(hdr)],
5111 DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, hdr);
5112 arc_change_state(arc_mfu, hdr);
5113 } else if (hdr->b_l1hdr.b_state == arc_uncached) {
5115 * This buffer is uncacheable, but we got a hit. Probably
5116 * a demand read after prefetch. Nothing more to do here.
5118 if (!HDR_IO_IN_PROGRESS(hdr))
5119 ARCSTAT_BUMP(arcstat_uncached_hits);
5120 hdr->b_l1hdr.b_arc_access = now;
5121 } else if (hdr->b_l1hdr.b_state == arc_l2c_only) {
5123 * This buffer is on the 2nd Level ARC and was not accessed
5124 * for a long time, so treat it as new and put into MRU.
5126 hdr->b_l1hdr.b_arc_access = now;
5127 DTRACE_PROBE1(new_state__mru, arc_buf_hdr_t *, hdr);
5128 arc_change_state(arc_mru, hdr);
5130 cmn_err(CE_PANIC, "invalid arc state 0x%p",
5131 hdr->b_l1hdr.b_state);
5136 * This routine is called by dbuf_hold() to update the arc_access() state
5137 * which otherwise would be skipped for entries in the dbuf cache.
5140 arc_buf_access(arc_buf_t *buf)
5142 arc_buf_hdr_t *hdr = buf->b_hdr;
5145 * Avoid taking the hash_lock when possible as an optimization.
5146 * The header must be checked again under the hash_lock in order
5147 * to handle the case where it is concurrently being released.
5149 if (hdr->b_l1hdr.b_state == arc_anon || HDR_EMPTY(hdr))
5152 kmutex_t *hash_lock = HDR_LOCK(hdr);
5153 mutex_enter(hash_lock);
5155 if (hdr->b_l1hdr.b_state == arc_anon || HDR_EMPTY(hdr)) {
5156 mutex_exit(hash_lock);
5157 ARCSTAT_BUMP(arcstat_access_skip);
5161 ASSERT(hdr->b_l1hdr.b_state == arc_mru ||
5162 hdr->b_l1hdr.b_state == arc_mfu ||
5163 hdr->b_l1hdr.b_state == arc_uncached);
5165 DTRACE_PROBE1(arc__hit, arc_buf_hdr_t *, hdr);
5166 arc_access(hdr, 0, B_TRUE);
5167 mutex_exit(hash_lock);
5169 ARCSTAT_BUMP(arcstat_hits);
5170 ARCSTAT_CONDSTAT(B_TRUE /* demand */, demand, prefetch,
5171 !HDR_ISTYPE_METADATA(hdr), data, metadata, hits);
5174 /* a generic arc_read_done_func_t which you can use */
5176 arc_bcopy_func(zio_t *zio, const zbookmark_phys_t *zb, const blkptr_t *bp,
5177 arc_buf_t *buf, void *arg)
5179 (void) zio, (void) zb, (void) bp;
5184 memcpy(arg, buf->b_data, arc_buf_size(buf));
5185 arc_buf_destroy(buf, arg);
5188 /* a generic arc_read_done_func_t */
5190 arc_getbuf_func(zio_t *zio, const zbookmark_phys_t *zb, const blkptr_t *bp,
5191 arc_buf_t *buf, void *arg)
5193 (void) zb, (void) bp;
5194 arc_buf_t **bufp = arg;
5197 ASSERT(zio == NULL || zio->io_error != 0);
5200 ASSERT(zio == NULL || zio->io_error == 0);
5202 ASSERT(buf->b_data != NULL);
5207 arc_hdr_verify(arc_buf_hdr_t *hdr, blkptr_t *bp)
5209 if (BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp)) {
5210 ASSERT3U(HDR_GET_PSIZE(hdr), ==, 0);
5211 ASSERT3U(arc_hdr_get_compress(hdr), ==, ZIO_COMPRESS_OFF);
5213 if (HDR_COMPRESSION_ENABLED(hdr)) {
5214 ASSERT3U(arc_hdr_get_compress(hdr), ==,
5215 BP_GET_COMPRESS(bp));
5217 ASSERT3U(HDR_GET_LSIZE(hdr), ==, BP_GET_LSIZE(bp));
5218 ASSERT3U(HDR_GET_PSIZE(hdr), ==, BP_GET_PSIZE(bp));
5219 ASSERT3U(!!HDR_PROTECTED(hdr), ==, BP_IS_PROTECTED(bp));
5224 arc_read_done(zio_t *zio)
5226 blkptr_t *bp = zio->io_bp;
5227 arc_buf_hdr_t *hdr = zio->io_private;
5228 kmutex_t *hash_lock = NULL;
5229 arc_callback_t *callback_list;
5230 arc_callback_t *acb;
5233 * The hdr was inserted into hash-table and removed from lists
5234 * prior to starting I/O. We should find this header, since
5235 * it's in the hash table, and it should be legit since it's
5236 * not possible to evict it during the I/O. The only possible
5237 * reason for it not to be found is if we were freed during the
5240 if (HDR_IN_HASH_TABLE(hdr)) {
5241 arc_buf_hdr_t *found;
5243 ASSERT3U(hdr->b_birth, ==, BP_PHYSICAL_BIRTH(zio->io_bp));
5244 ASSERT3U(hdr->b_dva.dva_word[0], ==,
5245 BP_IDENTITY(zio->io_bp)->dva_word[0]);
5246 ASSERT3U(hdr->b_dva.dva_word[1], ==,
5247 BP_IDENTITY(zio->io_bp)->dva_word[1]);
5249 found = buf_hash_find(hdr->b_spa, zio->io_bp, &hash_lock);
5251 ASSERT((found == hdr &&
5252 DVA_EQUAL(&hdr->b_dva, BP_IDENTITY(zio->io_bp))) ||
5253 (found == hdr && HDR_L2_READING(hdr)));
5254 ASSERT3P(hash_lock, !=, NULL);
5257 if (BP_IS_PROTECTED(bp)) {
5258 hdr->b_crypt_hdr.b_ot = BP_GET_TYPE(bp);
5259 hdr->b_crypt_hdr.b_dsobj = zio->io_bookmark.zb_objset;
5260 zio_crypt_decode_params_bp(bp, hdr->b_crypt_hdr.b_salt,
5261 hdr->b_crypt_hdr.b_iv);
5263 if (zio->io_error == 0) {
5264 if (BP_GET_TYPE(bp) == DMU_OT_INTENT_LOG) {
5267 tmpbuf = abd_borrow_buf_copy(zio->io_abd,
5268 sizeof (zil_chain_t));
5269 zio_crypt_decode_mac_zil(tmpbuf,
5270 hdr->b_crypt_hdr.b_mac);
5271 abd_return_buf(zio->io_abd, tmpbuf,
5272 sizeof (zil_chain_t));
5274 zio_crypt_decode_mac_bp(bp,
5275 hdr->b_crypt_hdr.b_mac);
5280 if (zio->io_error == 0) {
5281 /* byteswap if necessary */
5282 if (BP_SHOULD_BYTESWAP(zio->io_bp)) {
5283 if (BP_GET_LEVEL(zio->io_bp) > 0) {
5284 hdr->b_l1hdr.b_byteswap = DMU_BSWAP_UINT64;
5286 hdr->b_l1hdr.b_byteswap =
5287 DMU_OT_BYTESWAP(BP_GET_TYPE(zio->io_bp));
5290 hdr->b_l1hdr.b_byteswap = DMU_BSWAP_NUMFUNCS;
5292 if (!HDR_L2_READING(hdr)) {
5293 hdr->b_complevel = zio->io_prop.zp_complevel;
5297 arc_hdr_clear_flags(hdr, ARC_FLAG_L2_EVICTED);
5298 if (l2arc_noprefetch && HDR_PREFETCH(hdr))
5299 arc_hdr_clear_flags(hdr, ARC_FLAG_L2CACHE);
5301 callback_list = hdr->b_l1hdr.b_acb;
5302 ASSERT3P(callback_list, !=, NULL);
5303 hdr->b_l1hdr.b_acb = NULL;
5306 * If a read request has a callback (i.e. acb_done is not NULL), then we
5307 * make a buf containing the data according to the parameters which were
5308 * passed in. The implementation of arc_buf_alloc_impl() ensures that we
5309 * aren't needlessly decompressing the data multiple times.
5311 int callback_cnt = 0;
5312 for (acb = callback_list; acb != NULL; acb = acb->acb_next) {
5314 /* We need the last one to call below in original order. */
5315 callback_list = acb;
5317 if (!acb->acb_done || acb->acb_nobuf)
5322 if (zio->io_error != 0)
5325 int error = arc_buf_alloc_impl(hdr, zio->io_spa,
5326 &acb->acb_zb, acb->acb_private, acb->acb_encrypted,
5327 acb->acb_compressed, acb->acb_noauth, B_TRUE,
5331 * Assert non-speculative zios didn't fail because an
5332 * encryption key wasn't loaded
5334 ASSERT((zio->io_flags & ZIO_FLAG_SPECULATIVE) ||
5338 * If we failed to decrypt, report an error now (as the zio
5339 * layer would have done if it had done the transforms).
5341 if (error == ECKSUM) {
5342 ASSERT(BP_IS_PROTECTED(bp));
5343 error = SET_ERROR(EIO);
5344 if ((zio->io_flags & ZIO_FLAG_SPECULATIVE) == 0) {
5345 spa_log_error(zio->io_spa, &acb->acb_zb,
5346 &zio->io_bp->blk_birth);
5347 (void) zfs_ereport_post(
5348 FM_EREPORT_ZFS_AUTHENTICATION,
5349 zio->io_spa, NULL, &acb->acb_zb, zio, 0);
5355 * Decompression or decryption failed. Set
5356 * io_error so that when we call acb_done
5357 * (below), we will indicate that the read
5358 * failed. Note that in the unusual case
5359 * where one callback is compressed and another
5360 * uncompressed, we will mark all of them
5361 * as failed, even though the uncompressed
5362 * one can't actually fail. In this case,
5363 * the hdr will not be anonymous, because
5364 * if there are multiple callbacks, it's
5365 * because multiple threads found the same
5366 * arc buf in the hash table.
5368 zio->io_error = error;
5373 * If there are multiple callbacks, we must have the hash lock,
5374 * because the only way for multiple threads to find this hdr is
5375 * in the hash table. This ensures that if there are multiple
5376 * callbacks, the hdr is not anonymous. If it were anonymous,
5377 * we couldn't use arc_buf_destroy() in the error case below.
5379 ASSERT(callback_cnt < 2 || hash_lock != NULL);
5381 if (zio->io_error == 0) {
5382 arc_hdr_verify(hdr, zio->io_bp);
5384 arc_hdr_set_flags(hdr, ARC_FLAG_IO_ERROR);
5385 if (hdr->b_l1hdr.b_state != arc_anon)
5386 arc_change_state(arc_anon, hdr);
5387 if (HDR_IN_HASH_TABLE(hdr))
5388 buf_hash_remove(hdr);
5391 arc_hdr_clear_flags(hdr, ARC_FLAG_IO_IN_PROGRESS);
5392 (void) remove_reference(hdr, hdr);
5394 if (hash_lock != NULL)
5395 mutex_exit(hash_lock);
5397 /* execute each callback and free its structure */
5398 while ((acb = callback_list) != NULL) {
5399 if (acb->acb_done != NULL) {
5400 if (zio->io_error != 0 && acb->acb_buf != NULL) {
5402 * If arc_buf_alloc_impl() fails during
5403 * decompression, the buf will still be
5404 * allocated, and needs to be freed here.
5406 arc_buf_destroy(acb->acb_buf,
5408 acb->acb_buf = NULL;
5410 acb->acb_done(zio, &zio->io_bookmark, zio->io_bp,
5411 acb->acb_buf, acb->acb_private);
5414 if (acb->acb_zio_dummy != NULL) {
5415 acb->acb_zio_dummy->io_error = zio->io_error;
5416 zio_nowait(acb->acb_zio_dummy);
5419 callback_list = acb->acb_prev;
5420 if (acb->acb_wait) {
5421 mutex_enter(&acb->acb_wait_lock);
5422 acb->acb_wait_error = zio->io_error;
5423 acb->acb_wait = B_FALSE;
5424 cv_signal(&acb->acb_wait_cv);
5425 mutex_exit(&acb->acb_wait_lock);
5426 /* acb will be freed by the waiting thread. */
5428 kmem_free(acb, sizeof (arc_callback_t));
5434 * "Read" the block at the specified DVA (in bp) via the
5435 * cache. If the block is found in the cache, invoke the provided
5436 * callback immediately and return. Note that the `zio' parameter
5437 * in the callback will be NULL in this case, since no IO was
5438 * required. If the block is not in the cache pass the read request
5439 * on to the spa with a substitute callback function, so that the
5440 * requested block will be added to the cache.
5442 * If a read request arrives for a block that has a read in-progress,
5443 * either wait for the in-progress read to complete (and return the
5444 * results); or, if this is a read with a "done" func, add a record
5445 * to the read to invoke the "done" func when the read completes,
5446 * and return; or just return.
5448 * arc_read_done() will invoke all the requested "done" functions
5449 * for readers of this block.
5452 arc_read(zio_t *pio, spa_t *spa, const blkptr_t *bp,
5453 arc_read_done_func_t *done, void *private, zio_priority_t priority,
5454 int zio_flags, arc_flags_t *arc_flags, const zbookmark_phys_t *zb)
5456 arc_buf_hdr_t *hdr = NULL;
5457 kmutex_t *hash_lock = NULL;
5459 uint64_t guid = spa_load_guid(spa);
5460 boolean_t compressed_read = (zio_flags & ZIO_FLAG_RAW_COMPRESS) != 0;
5461 boolean_t encrypted_read = BP_IS_ENCRYPTED(bp) &&
5462 (zio_flags & ZIO_FLAG_RAW_ENCRYPT) != 0;
5463 boolean_t noauth_read = BP_IS_AUTHENTICATED(bp) &&
5464 (zio_flags & ZIO_FLAG_RAW_ENCRYPT) != 0;
5465 boolean_t embedded_bp = !!BP_IS_EMBEDDED(bp);
5466 boolean_t no_buf = *arc_flags & ARC_FLAG_NO_BUF;
5467 arc_buf_t *buf = NULL;
5470 ASSERT(!embedded_bp ||
5471 BPE_GET_ETYPE(bp) == BP_EMBEDDED_TYPE_DATA);
5472 ASSERT(!BP_IS_HOLE(bp));
5473 ASSERT(!BP_IS_REDACTED(bp));
5476 * Normally SPL_FSTRANS will already be set since kernel threads which
5477 * expect to call the DMU interfaces will set it when created. System
5478 * calls are similarly handled by setting/cleaning the bit in the
5479 * registered callback (module/os/.../zfs/zpl_*).
5481 * External consumers such as Lustre which call the exported DMU
5482 * interfaces may not have set SPL_FSTRANS. To avoid a deadlock
5483 * on the hash_lock always set and clear the bit.
5485 fstrans_cookie_t cookie = spl_fstrans_mark();
5488 * Verify the block pointer contents are reasonable. This should
5489 * always be the case since the blkptr is protected by a checksum.
5490 * However, if there is damage it's desirable to detect this early
5491 * and treat it as a checksum error. This allows an alternate blkptr
5492 * to be tried when one is available (e.g. ditto blocks).
5494 if (!zfs_blkptr_verify(spa, bp, (zio_flags & ZIO_FLAG_CONFIG_WRITER) ?
5495 BLK_CONFIG_HELD : BLK_CONFIG_NEEDED, BLK_VERIFY_LOG)) {
5496 rc = SET_ERROR(ECKSUM);
5502 * Embedded BP's have no DVA and require no I/O to "read".
5503 * Create an anonymous arc buf to back it.
5505 hdr = buf_hash_find(guid, bp, &hash_lock);
5509 * Determine if we have an L1 cache hit or a cache miss. For simplicity
5510 * we maintain encrypted data separately from compressed / uncompressed
5511 * data. If the user is requesting raw encrypted data and we don't have
5512 * that in the header we will read from disk to guarantee that we can
5513 * get it even if the encryption keys aren't loaded.
5515 if (hdr != NULL && HDR_HAS_L1HDR(hdr) && (HDR_HAS_RABD(hdr) ||
5516 (hdr->b_l1hdr.b_pabd != NULL && !encrypted_read))) {
5517 boolean_t is_data = !HDR_ISTYPE_METADATA(hdr);
5519 if (HDR_IO_IN_PROGRESS(hdr)) {
5520 if (*arc_flags & ARC_FLAG_CACHED_ONLY) {
5521 mutex_exit(hash_lock);
5522 ARCSTAT_BUMP(arcstat_cached_only_in_progress);
5523 rc = SET_ERROR(ENOENT);
5527 zio_t *head_zio = hdr->b_l1hdr.b_acb->acb_zio_head;
5528 ASSERT3P(head_zio, !=, NULL);
5529 if ((hdr->b_flags & ARC_FLAG_PRIO_ASYNC_READ) &&
5530 priority == ZIO_PRIORITY_SYNC_READ) {
5532 * This is a sync read that needs to wait for
5533 * an in-flight async read. Request that the
5534 * zio have its priority upgraded.
5536 zio_change_priority(head_zio, priority);
5537 DTRACE_PROBE1(arc__async__upgrade__sync,
5538 arc_buf_hdr_t *, hdr);
5539 ARCSTAT_BUMP(arcstat_async_upgrade_sync);
5542 DTRACE_PROBE1(arc__iohit, arc_buf_hdr_t *, hdr);
5543 arc_access(hdr, *arc_flags, B_FALSE);
5546 * If there are multiple threads reading the same block
5547 * and that block is not yet in the ARC, then only one
5548 * thread will do the physical I/O and all other
5549 * threads will wait until that I/O completes.
5550 * Synchronous reads use the acb_wait_cv whereas nowait
5551 * reads register a callback. Both are signalled/called
5554 * Errors of the physical I/O may need to be propagated.
5555 * Synchronous read errors are returned here from
5556 * arc_read_done via acb_wait_error. Nowait reads
5557 * attach the acb_zio_dummy zio to pio and
5558 * arc_read_done propagates the physical I/O's io_error
5559 * to acb_zio_dummy, and thereby to pio.
5561 arc_callback_t *acb = NULL;
5562 if (done || pio || *arc_flags & ARC_FLAG_WAIT) {
5563 acb = kmem_zalloc(sizeof (arc_callback_t),
5565 acb->acb_done = done;
5566 acb->acb_private = private;
5567 acb->acb_compressed = compressed_read;
5568 acb->acb_encrypted = encrypted_read;
5569 acb->acb_noauth = noauth_read;
5570 acb->acb_nobuf = no_buf;
5571 if (*arc_flags & ARC_FLAG_WAIT) {
5572 acb->acb_wait = B_TRUE;
5573 mutex_init(&acb->acb_wait_lock, NULL,
5574 MUTEX_DEFAULT, NULL);
5575 cv_init(&acb->acb_wait_cv, NULL,
5580 acb->acb_zio_dummy = zio_null(pio,
5581 spa, NULL, NULL, NULL, zio_flags);
5583 acb->acb_zio_head = head_zio;
5584 acb->acb_next = hdr->b_l1hdr.b_acb;
5585 hdr->b_l1hdr.b_acb->acb_prev = acb;
5586 hdr->b_l1hdr.b_acb = acb;
5588 mutex_exit(hash_lock);
5590 ARCSTAT_BUMP(arcstat_iohits);
5591 ARCSTAT_CONDSTAT(!(*arc_flags & ARC_FLAG_PREFETCH),
5592 demand, prefetch, is_data, data, metadata, iohits);
5594 if (*arc_flags & ARC_FLAG_WAIT) {
5595 mutex_enter(&acb->acb_wait_lock);
5596 while (acb->acb_wait) {
5597 cv_wait(&acb->acb_wait_cv,
5598 &acb->acb_wait_lock);
5600 rc = acb->acb_wait_error;
5601 mutex_exit(&acb->acb_wait_lock);
5602 mutex_destroy(&acb->acb_wait_lock);
5603 cv_destroy(&acb->acb_wait_cv);
5604 kmem_free(acb, sizeof (arc_callback_t));
5609 ASSERT(hdr->b_l1hdr.b_state == arc_mru ||
5610 hdr->b_l1hdr.b_state == arc_mfu ||
5611 hdr->b_l1hdr.b_state == arc_uncached);
5613 DTRACE_PROBE1(arc__hit, arc_buf_hdr_t *, hdr);
5614 arc_access(hdr, *arc_flags, B_TRUE);
5616 if (done && !no_buf) {
5617 ASSERT(!embedded_bp || !BP_IS_HOLE(bp));
5619 /* Get a buf with the desired data in it. */
5620 rc = arc_buf_alloc_impl(hdr, spa, zb, private,
5621 encrypted_read, compressed_read, noauth_read,
5625 * Convert authentication and decryption errors
5626 * to EIO (and generate an ereport if needed)
5627 * before leaving the ARC.
5629 rc = SET_ERROR(EIO);
5630 if ((zio_flags & ZIO_FLAG_SPECULATIVE) == 0) {
5631 spa_log_error(spa, zb, &hdr->b_birth);
5632 (void) zfs_ereport_post(
5633 FM_EREPORT_ZFS_AUTHENTICATION,
5634 spa, NULL, zb, NULL, 0);
5638 arc_buf_destroy_impl(buf);
5640 (void) remove_reference(hdr, private);
5643 /* assert any errors weren't due to unloaded keys */
5644 ASSERT((zio_flags & ZIO_FLAG_SPECULATIVE) ||
5647 mutex_exit(hash_lock);
5648 ARCSTAT_BUMP(arcstat_hits);
5649 ARCSTAT_CONDSTAT(!(*arc_flags & ARC_FLAG_PREFETCH),
5650 demand, prefetch, is_data, data, metadata, hits);
5651 *arc_flags |= ARC_FLAG_CACHED;
5654 uint64_t lsize = BP_GET_LSIZE(bp);
5655 uint64_t psize = BP_GET_PSIZE(bp);
5656 arc_callback_t *acb;
5659 boolean_t devw = B_FALSE;
5662 int alloc_flags = encrypted_read ? ARC_HDR_ALLOC_RDATA : 0;
5663 arc_buf_contents_t type = BP_GET_BUFC_TYPE(bp);
5665 if (*arc_flags & ARC_FLAG_CACHED_ONLY) {
5666 if (hash_lock != NULL)
5667 mutex_exit(hash_lock);
5668 rc = SET_ERROR(ENOENT);
5674 * This block is not in the cache or it has
5677 arc_buf_hdr_t *exists = NULL;
5678 hdr = arc_hdr_alloc(spa_load_guid(spa), psize, lsize,
5679 BP_IS_PROTECTED(bp), BP_GET_COMPRESS(bp), 0, type);
5682 hdr->b_dva = *BP_IDENTITY(bp);
5683 hdr->b_birth = BP_PHYSICAL_BIRTH(bp);
5684 exists = buf_hash_insert(hdr, &hash_lock);
5686 if (exists != NULL) {
5687 /* somebody beat us to the hash insert */
5688 mutex_exit(hash_lock);
5689 buf_discard_identity(hdr);
5690 arc_hdr_destroy(hdr);
5691 goto top; /* restart the IO request */
5695 * This block is in the ghost cache or encrypted data
5696 * was requested and we didn't have it. If it was
5697 * L2-only (and thus didn't have an L1 hdr),
5698 * we realloc the header to add an L1 hdr.
5700 if (!HDR_HAS_L1HDR(hdr)) {
5701 hdr = arc_hdr_realloc(hdr, hdr_l2only_cache,
5705 if (GHOST_STATE(hdr->b_l1hdr.b_state)) {
5706 ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
5707 ASSERT(!HDR_HAS_RABD(hdr));
5708 ASSERT(!HDR_IO_IN_PROGRESS(hdr));
5709 ASSERT0(zfs_refcount_count(
5710 &hdr->b_l1hdr.b_refcnt));
5711 ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL);
5713 ASSERT3P(hdr->b_l1hdr.b_freeze_cksum, ==, NULL);
5715 } else if (HDR_IO_IN_PROGRESS(hdr)) {
5717 * If this header already had an IO in progress
5718 * and we are performing another IO to fetch
5719 * encrypted data we must wait until the first
5720 * IO completes so as not to confuse
5721 * arc_read_done(). This should be very rare
5722 * and so the performance impact shouldn't
5725 arc_callback_t *acb = kmem_zalloc(
5726 sizeof (arc_callback_t), KM_SLEEP);
5727 acb->acb_wait = B_TRUE;
5728 mutex_init(&acb->acb_wait_lock, NULL,
5729 MUTEX_DEFAULT, NULL);
5730 cv_init(&acb->acb_wait_cv, NULL, CV_DEFAULT,
5733 hdr->b_l1hdr.b_acb->acb_zio_head;
5734 acb->acb_next = hdr->b_l1hdr.b_acb;
5735 hdr->b_l1hdr.b_acb->acb_prev = acb;
5736 hdr->b_l1hdr.b_acb = acb;
5737 mutex_exit(hash_lock);
5738 mutex_enter(&acb->acb_wait_lock);
5739 while (acb->acb_wait) {
5740 cv_wait(&acb->acb_wait_cv,
5741 &acb->acb_wait_lock);
5743 mutex_exit(&acb->acb_wait_lock);
5744 mutex_destroy(&acb->acb_wait_lock);
5745 cv_destroy(&acb->acb_wait_cv);
5746 kmem_free(acb, sizeof (arc_callback_t));
5750 if (*arc_flags & ARC_FLAG_UNCACHED) {
5751 arc_hdr_set_flags(hdr, ARC_FLAG_UNCACHED);
5752 if (!encrypted_read)
5753 alloc_flags |= ARC_HDR_ALLOC_LINEAR;
5757 * Take additional reference for IO_IN_PROGRESS. It stops
5758 * arc_access() from putting this header without any buffers
5759 * and so other references but obviously nonevictable onto
5760 * the evictable list of MRU or MFU state.
5762 add_reference(hdr, hdr);
5764 arc_access(hdr, *arc_flags, B_FALSE);
5765 arc_hdr_set_flags(hdr, ARC_FLAG_IO_IN_PROGRESS);
5766 arc_hdr_alloc_abd(hdr, alloc_flags);
5767 if (encrypted_read) {
5768 ASSERT(HDR_HAS_RABD(hdr));
5769 size = HDR_GET_PSIZE(hdr);
5770 hdr_abd = hdr->b_crypt_hdr.b_rabd;
5771 zio_flags |= ZIO_FLAG_RAW;
5773 ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
5774 size = arc_hdr_size(hdr);
5775 hdr_abd = hdr->b_l1hdr.b_pabd;
5777 if (arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF) {
5778 zio_flags |= ZIO_FLAG_RAW_COMPRESS;
5782 * For authenticated bp's, we do not ask the ZIO layer
5783 * to authenticate them since this will cause the entire
5784 * IO to fail if the key isn't loaded. Instead, we
5785 * defer authentication until arc_buf_fill(), which will
5786 * verify the data when the key is available.
5788 if (BP_IS_AUTHENTICATED(bp))
5789 zio_flags |= ZIO_FLAG_RAW_ENCRYPT;
5792 if (BP_IS_AUTHENTICATED(bp))
5793 arc_hdr_set_flags(hdr, ARC_FLAG_NOAUTH);
5794 if (BP_GET_LEVEL(bp) > 0)
5795 arc_hdr_set_flags(hdr, ARC_FLAG_INDIRECT);
5796 ASSERT(!GHOST_STATE(hdr->b_l1hdr.b_state));
5798 acb = kmem_zalloc(sizeof (arc_callback_t), KM_SLEEP);
5799 acb->acb_done = done;
5800 acb->acb_private = private;
5801 acb->acb_compressed = compressed_read;
5802 acb->acb_encrypted = encrypted_read;
5803 acb->acb_noauth = noauth_read;
5806 ASSERT3P(hdr->b_l1hdr.b_acb, ==, NULL);
5807 hdr->b_l1hdr.b_acb = acb;
5809 if (HDR_HAS_L2HDR(hdr) &&
5810 (vd = hdr->b_l2hdr.b_dev->l2ad_vdev) != NULL) {
5811 devw = hdr->b_l2hdr.b_dev->l2ad_writing;
5812 addr = hdr->b_l2hdr.b_daddr;
5814 * Lock out L2ARC device removal.
5816 if (vdev_is_dead(vd) ||
5817 !spa_config_tryenter(spa, SCL_L2ARC, vd, RW_READER))
5822 * We count both async reads and scrub IOs as asynchronous so
5823 * that both can be upgraded in the event of a cache hit while
5824 * the read IO is still in-flight.
5826 if (priority == ZIO_PRIORITY_ASYNC_READ ||
5827 priority == ZIO_PRIORITY_SCRUB)
5828 arc_hdr_set_flags(hdr, ARC_FLAG_PRIO_ASYNC_READ);
5830 arc_hdr_clear_flags(hdr, ARC_FLAG_PRIO_ASYNC_READ);
5833 * At this point, we have a level 1 cache miss or a blkptr
5834 * with embedded data. Try again in L2ARC if possible.
5836 ASSERT3U(HDR_GET_LSIZE(hdr), ==, lsize);
5839 * Skip ARC stat bump for block pointers with embedded
5840 * data. The data are read from the blkptr itself via
5841 * decode_embedded_bp_compressed().
5844 DTRACE_PROBE4(arc__miss, arc_buf_hdr_t *, hdr,
5845 blkptr_t *, bp, uint64_t, lsize,
5846 zbookmark_phys_t *, zb);
5847 ARCSTAT_BUMP(arcstat_misses);
5848 ARCSTAT_CONDSTAT(!(*arc_flags & ARC_FLAG_PREFETCH),
5849 demand, prefetch, !HDR_ISTYPE_METADATA(hdr), data,
5851 zfs_racct_read(size, 1);
5854 /* Check if the spa even has l2 configured */
5855 const boolean_t spa_has_l2 = l2arc_ndev != 0 &&
5856 spa->spa_l2cache.sav_count > 0;
5858 if (vd != NULL && spa_has_l2 && !(l2arc_norw && devw)) {
5860 * Read from the L2ARC if the following are true:
5861 * 1. The L2ARC vdev was previously cached.
5862 * 2. This buffer still has L2ARC metadata.
5863 * 3. This buffer isn't currently writing to the L2ARC.
5864 * 4. The L2ARC entry wasn't evicted, which may
5865 * also have invalidated the vdev.
5866 * 5. This isn't prefetch or l2arc_noprefetch is 0.
5868 if (HDR_HAS_L2HDR(hdr) &&
5869 !HDR_L2_WRITING(hdr) && !HDR_L2_EVICTED(hdr) &&
5870 !(l2arc_noprefetch &&
5871 (*arc_flags & ARC_FLAG_PREFETCH))) {
5872 l2arc_read_callback_t *cb;
5876 DTRACE_PROBE1(l2arc__hit, arc_buf_hdr_t *, hdr);
5877 ARCSTAT_BUMP(arcstat_l2_hits);
5878 hdr->b_l2hdr.b_hits++;
5880 cb = kmem_zalloc(sizeof (l2arc_read_callback_t),
5882 cb->l2rcb_hdr = hdr;
5885 cb->l2rcb_flags = zio_flags;
5888 * When Compressed ARC is disabled, but the
5889 * L2ARC block is compressed, arc_hdr_size()
5890 * will have returned LSIZE rather than PSIZE.
5892 if (HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF &&
5893 !HDR_COMPRESSION_ENABLED(hdr) &&
5894 HDR_GET_PSIZE(hdr) != 0) {
5895 size = HDR_GET_PSIZE(hdr);
5898 asize = vdev_psize_to_asize(vd, size);
5899 if (asize != size) {
5900 abd = abd_alloc_for_io(asize,
5901 HDR_ISTYPE_METADATA(hdr));
5902 cb->l2rcb_abd = abd;
5907 ASSERT(addr >= VDEV_LABEL_START_SIZE &&
5908 addr + asize <= vd->vdev_psize -
5909 VDEV_LABEL_END_SIZE);
5912 * l2arc read. The SCL_L2ARC lock will be
5913 * released by l2arc_read_done().
5914 * Issue a null zio if the underlying buffer
5915 * was squashed to zero size by compression.
5917 ASSERT3U(arc_hdr_get_compress(hdr), !=,
5918 ZIO_COMPRESS_EMPTY);
5919 rzio = zio_read_phys(pio, vd, addr,
5922 l2arc_read_done, cb, priority,
5923 zio_flags | ZIO_FLAG_CANFAIL |
5924 ZIO_FLAG_DONT_PROPAGATE |
5925 ZIO_FLAG_DONT_RETRY, B_FALSE);
5926 acb->acb_zio_head = rzio;
5928 if (hash_lock != NULL)
5929 mutex_exit(hash_lock);
5931 DTRACE_PROBE2(l2arc__read, vdev_t *, vd,
5933 ARCSTAT_INCR(arcstat_l2_read_bytes,
5934 HDR_GET_PSIZE(hdr));
5936 if (*arc_flags & ARC_FLAG_NOWAIT) {
5941 ASSERT(*arc_flags & ARC_FLAG_WAIT);
5942 if (zio_wait(rzio) == 0)
5945 /* l2arc read error; goto zio_read() */
5946 if (hash_lock != NULL)
5947 mutex_enter(hash_lock);
5949 DTRACE_PROBE1(l2arc__miss,
5950 arc_buf_hdr_t *, hdr);
5951 ARCSTAT_BUMP(arcstat_l2_misses);
5952 if (HDR_L2_WRITING(hdr))
5953 ARCSTAT_BUMP(arcstat_l2_rw_clash);
5954 spa_config_exit(spa, SCL_L2ARC, vd);
5958 spa_config_exit(spa, SCL_L2ARC, vd);
5961 * Only a spa with l2 should contribute to l2
5962 * miss stats. (Including the case of having a
5963 * faulted cache device - that's also a miss.)
5967 * Skip ARC stat bump for block pointers with
5968 * embedded data. The data are read from the
5970 * decode_embedded_bp_compressed().
5973 DTRACE_PROBE1(l2arc__miss,
5974 arc_buf_hdr_t *, hdr);
5975 ARCSTAT_BUMP(arcstat_l2_misses);
5980 rzio = zio_read(pio, spa, bp, hdr_abd, size,
5981 arc_read_done, hdr, priority, zio_flags, zb);
5982 acb->acb_zio_head = rzio;
5984 if (hash_lock != NULL)
5985 mutex_exit(hash_lock);
5987 if (*arc_flags & ARC_FLAG_WAIT) {
5988 rc = zio_wait(rzio);
5992 ASSERT(*arc_flags & ARC_FLAG_NOWAIT);
5997 /* embedded bps don't actually go to disk */
5999 spa_read_history_add(spa, zb, *arc_flags);
6000 spl_fstrans_unmark(cookie);
6005 done(NULL, zb, bp, buf, private);
6006 if (pio && rc != 0) {
6007 zio_t *zio = zio_null(pio, spa, NULL, NULL, NULL, zio_flags);
6015 arc_add_prune_callback(arc_prune_func_t *func, void *private)
6019 p = kmem_alloc(sizeof (*p), KM_SLEEP);
6021 p->p_private = private;
6022 list_link_init(&p->p_node);
6023 zfs_refcount_create(&p->p_refcnt);
6025 mutex_enter(&arc_prune_mtx);
6026 zfs_refcount_add(&p->p_refcnt, &arc_prune_list);
6027 list_insert_head(&arc_prune_list, p);
6028 mutex_exit(&arc_prune_mtx);
6034 arc_remove_prune_callback(arc_prune_t *p)
6036 boolean_t wait = B_FALSE;
6037 mutex_enter(&arc_prune_mtx);
6038 list_remove(&arc_prune_list, p);
6039 if (zfs_refcount_remove(&p->p_refcnt, &arc_prune_list) > 0)
6041 mutex_exit(&arc_prune_mtx);
6043 /* wait for arc_prune_task to finish */
6045 taskq_wait_outstanding(arc_prune_taskq, 0);
6046 ASSERT0(zfs_refcount_count(&p->p_refcnt));
6047 zfs_refcount_destroy(&p->p_refcnt);
6048 kmem_free(p, sizeof (*p));
6052 * Notify the arc that a block was freed, and thus will never be used again.
6055 arc_freed(spa_t *spa, const blkptr_t *bp)
6058 kmutex_t *hash_lock;
6059 uint64_t guid = spa_load_guid(spa);
6061 ASSERT(!BP_IS_EMBEDDED(bp));
6063 hdr = buf_hash_find(guid, bp, &hash_lock);
6068 * We might be trying to free a block that is still doing I/O
6069 * (i.e. prefetch) or has some other reference (i.e. a dedup-ed,
6070 * dmu_sync-ed block). A block may also have a reference if it is
6071 * part of a dedup-ed, dmu_synced write. The dmu_sync() function would
6072 * have written the new block to its final resting place on disk but
6073 * without the dedup flag set. This would have left the hdr in the MRU
6074 * state and discoverable. When the txg finally syncs it detects that
6075 * the block was overridden in open context and issues an override I/O.
6076 * Since this is a dedup block, the override I/O will determine if the
6077 * block is already in the DDT. If so, then it will replace the io_bp
6078 * with the bp from the DDT and allow the I/O to finish. When the I/O
6079 * reaches the done callback, dbuf_write_override_done, it will
6080 * check to see if the io_bp and io_bp_override are identical.
6081 * If they are not, then it indicates that the bp was replaced with
6082 * the bp in the DDT and the override bp is freed. This allows
6083 * us to arrive here with a reference on a block that is being
6084 * freed. So if we have an I/O in progress, or a reference to
6085 * this hdr, then we don't destroy the hdr.
6087 if (!HDR_HAS_L1HDR(hdr) ||
6088 zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt)) {
6089 arc_change_state(arc_anon, hdr);
6090 arc_hdr_destroy(hdr);
6091 mutex_exit(hash_lock);
6093 mutex_exit(hash_lock);
6099 * Release this buffer from the cache, making it an anonymous buffer. This
6100 * must be done after a read and prior to modifying the buffer contents.
6101 * If the buffer has more than one reference, we must make
6102 * a new hdr for the buffer.
6105 arc_release(arc_buf_t *buf, const void *tag)
6107 arc_buf_hdr_t *hdr = buf->b_hdr;
6110 * It would be nice to assert that if its DMU metadata (level >
6111 * 0 || it's the dnode file), then it must be syncing context.
6112 * But we don't know that information at this level.
6115 ASSERT(HDR_HAS_L1HDR(hdr));
6118 * We don't grab the hash lock prior to this check, because if
6119 * the buffer's header is in the arc_anon state, it won't be
6120 * linked into the hash table.
6122 if (hdr->b_l1hdr.b_state == arc_anon) {
6123 ASSERT(!HDR_IO_IN_PROGRESS(hdr));
6124 ASSERT(!HDR_IN_HASH_TABLE(hdr));
6125 ASSERT(!HDR_HAS_L2HDR(hdr));
6127 ASSERT3P(hdr->b_l1hdr.b_buf, ==, buf);
6128 ASSERT(ARC_BUF_LAST(buf));
6129 ASSERT3S(zfs_refcount_count(&hdr->b_l1hdr.b_refcnt), ==, 1);
6130 ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node));
6132 hdr->b_l1hdr.b_arc_access = 0;
6135 * If the buf is being overridden then it may already
6136 * have a hdr that is not empty.
6138 buf_discard_identity(hdr);
6144 kmutex_t *hash_lock = HDR_LOCK(hdr);
6145 mutex_enter(hash_lock);
6148 * This assignment is only valid as long as the hash_lock is
6149 * held, we must be careful not to reference state or the
6150 * b_state field after dropping the lock.
6152 arc_state_t *state = hdr->b_l1hdr.b_state;
6153 ASSERT3P(hash_lock, ==, HDR_LOCK(hdr));
6154 ASSERT3P(state, !=, arc_anon);
6156 /* this buffer is not on any list */
6157 ASSERT3S(zfs_refcount_count(&hdr->b_l1hdr.b_refcnt), >, 0);
6159 if (HDR_HAS_L2HDR(hdr)) {
6160 mutex_enter(&hdr->b_l2hdr.b_dev->l2ad_mtx);
6163 * We have to recheck this conditional again now that
6164 * we're holding the l2ad_mtx to prevent a race with
6165 * another thread which might be concurrently calling
6166 * l2arc_evict(). In that case, l2arc_evict() might have
6167 * destroyed the header's L2 portion as we were waiting
6168 * to acquire the l2ad_mtx.
6170 if (HDR_HAS_L2HDR(hdr))
6171 arc_hdr_l2hdr_destroy(hdr);
6173 mutex_exit(&hdr->b_l2hdr.b_dev->l2ad_mtx);
6177 * Do we have more than one buf?
6179 if (hdr->b_l1hdr.b_buf != buf || !ARC_BUF_LAST(buf)) {
6180 arc_buf_hdr_t *nhdr;
6181 uint64_t spa = hdr->b_spa;
6182 uint64_t psize = HDR_GET_PSIZE(hdr);
6183 uint64_t lsize = HDR_GET_LSIZE(hdr);
6184 boolean_t protected = HDR_PROTECTED(hdr);
6185 enum zio_compress compress = arc_hdr_get_compress(hdr);
6186 arc_buf_contents_t type = arc_buf_type(hdr);
6187 VERIFY3U(hdr->b_type, ==, type);
6189 ASSERT(hdr->b_l1hdr.b_buf != buf || buf->b_next != NULL);
6190 VERIFY3S(remove_reference(hdr, tag), >, 0);
6192 if (arc_buf_is_shared(buf) && !ARC_BUF_COMPRESSED(buf)) {
6193 ASSERT3P(hdr->b_l1hdr.b_buf, !=, buf);
6194 ASSERT(ARC_BUF_LAST(buf));
6198 * Pull the data off of this hdr and attach it to
6199 * a new anonymous hdr. Also find the last buffer
6200 * in the hdr's buffer list.
6202 arc_buf_t *lastbuf = arc_buf_remove(hdr, buf);
6203 ASSERT3P(lastbuf, !=, NULL);
6206 * If the current arc_buf_t and the hdr are sharing their data
6207 * buffer, then we must stop sharing that block.
6209 if (arc_buf_is_shared(buf)) {
6210 ASSERT3P(hdr->b_l1hdr.b_buf, !=, buf);
6211 VERIFY(!arc_buf_is_shared(lastbuf));
6214 * First, sever the block sharing relationship between
6215 * buf and the arc_buf_hdr_t.
6217 arc_unshare_buf(hdr, buf);
6220 * Now we need to recreate the hdr's b_pabd. Since we
6221 * have lastbuf handy, we try to share with it, but if
6222 * we can't then we allocate a new b_pabd and copy the
6223 * data from buf into it.
6225 if (arc_can_share(hdr, lastbuf)) {
6226 arc_share_buf(hdr, lastbuf);
6228 arc_hdr_alloc_abd(hdr, 0);
6229 abd_copy_from_buf(hdr->b_l1hdr.b_pabd,
6230 buf->b_data, psize);
6232 VERIFY3P(lastbuf->b_data, !=, NULL);
6233 } else if (HDR_SHARED_DATA(hdr)) {
6235 * Uncompressed shared buffers are always at the end
6236 * of the list. Compressed buffers don't have the
6237 * same requirements. This makes it hard to
6238 * simply assert that the lastbuf is shared so
6239 * we rely on the hdr's compression flags to determine
6240 * if we have a compressed, shared buffer.
6242 ASSERT(arc_buf_is_shared(lastbuf) ||
6243 arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF);
6244 ASSERT(!ARC_BUF_SHARED(buf));
6247 ASSERT(hdr->b_l1hdr.b_pabd != NULL || HDR_HAS_RABD(hdr));
6248 ASSERT3P(state, !=, arc_l2c_only);
6250 (void) zfs_refcount_remove_many(&state->arcs_size[type],
6251 arc_buf_size(buf), buf);
6253 if (zfs_refcount_is_zero(&hdr->b_l1hdr.b_refcnt)) {
6254 ASSERT3P(state, !=, arc_l2c_only);
6255 (void) zfs_refcount_remove_many(
6256 &state->arcs_esize[type],
6257 arc_buf_size(buf), buf);
6260 arc_cksum_verify(buf);
6261 arc_buf_unwatch(buf);
6263 /* if this is the last uncompressed buf free the checksum */
6264 if (!arc_hdr_has_uncompressed_buf(hdr))
6265 arc_cksum_free(hdr);
6267 mutex_exit(hash_lock);
6269 nhdr = arc_hdr_alloc(spa, psize, lsize, protected,
6270 compress, hdr->b_complevel, type);
6271 ASSERT3P(nhdr->b_l1hdr.b_buf, ==, NULL);
6272 ASSERT0(zfs_refcount_count(&nhdr->b_l1hdr.b_refcnt));
6273 VERIFY3U(nhdr->b_type, ==, type);
6274 ASSERT(!HDR_SHARED_DATA(nhdr));
6276 nhdr->b_l1hdr.b_buf = buf;
6277 (void) zfs_refcount_add(&nhdr->b_l1hdr.b_refcnt, tag);
6280 (void) zfs_refcount_add_many(&arc_anon->arcs_size[type],
6281 arc_buf_size(buf), buf);
6283 ASSERT(zfs_refcount_count(&hdr->b_l1hdr.b_refcnt) == 1);
6284 /* protected by hash lock, or hdr is on arc_anon */
6285 ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node));
6286 ASSERT(!HDR_IO_IN_PROGRESS(hdr));
6287 hdr->b_l1hdr.b_mru_hits = 0;
6288 hdr->b_l1hdr.b_mru_ghost_hits = 0;
6289 hdr->b_l1hdr.b_mfu_hits = 0;
6290 hdr->b_l1hdr.b_mfu_ghost_hits = 0;
6291 arc_change_state(arc_anon, hdr);
6292 hdr->b_l1hdr.b_arc_access = 0;
6294 mutex_exit(hash_lock);
6295 buf_discard_identity(hdr);
6301 arc_released(arc_buf_t *buf)
6303 return (buf->b_data != NULL &&
6304 buf->b_hdr->b_l1hdr.b_state == arc_anon);
6309 arc_referenced(arc_buf_t *buf)
6311 return (zfs_refcount_count(&buf->b_hdr->b_l1hdr.b_refcnt));
6316 arc_write_ready(zio_t *zio)
6318 arc_write_callback_t *callback = zio->io_private;
6319 arc_buf_t *buf = callback->awcb_buf;
6320 arc_buf_hdr_t *hdr = buf->b_hdr;
6321 blkptr_t *bp = zio->io_bp;
6322 uint64_t psize = BP_IS_HOLE(bp) ? 0 : BP_GET_PSIZE(bp);
6323 fstrans_cookie_t cookie = spl_fstrans_mark();
6325 ASSERT(HDR_HAS_L1HDR(hdr));
6326 ASSERT(!zfs_refcount_is_zero(&buf->b_hdr->b_l1hdr.b_refcnt));
6327 ASSERT3P(hdr->b_l1hdr.b_buf, !=, NULL);
6330 * If we're reexecuting this zio because the pool suspended, then
6331 * cleanup any state that was previously set the first time the
6332 * callback was invoked.
6334 if (zio->io_flags & ZIO_FLAG_REEXECUTED) {
6335 arc_cksum_free(hdr);
6336 arc_buf_unwatch(buf);
6337 if (hdr->b_l1hdr.b_pabd != NULL) {
6338 if (arc_buf_is_shared(buf)) {
6339 arc_unshare_buf(hdr, buf);
6341 arc_hdr_free_abd(hdr, B_FALSE);
6345 if (HDR_HAS_RABD(hdr))
6346 arc_hdr_free_abd(hdr, B_TRUE);
6348 ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
6349 ASSERT(!HDR_HAS_RABD(hdr));
6350 ASSERT(!HDR_SHARED_DATA(hdr));
6351 ASSERT(!arc_buf_is_shared(buf));
6353 callback->awcb_ready(zio, buf, callback->awcb_private);
6355 if (HDR_IO_IN_PROGRESS(hdr)) {
6356 ASSERT(zio->io_flags & ZIO_FLAG_REEXECUTED);
6358 arc_hdr_set_flags(hdr, ARC_FLAG_IO_IN_PROGRESS);
6359 add_reference(hdr, hdr); /* For IO_IN_PROGRESS. */
6362 if (BP_IS_PROTECTED(bp)) {
6363 /* ZIL blocks are written through zio_rewrite */
6364 ASSERT3U(BP_GET_TYPE(bp), !=, DMU_OT_INTENT_LOG);
6366 if (BP_SHOULD_BYTESWAP(bp)) {
6367 if (BP_GET_LEVEL(bp) > 0) {
6368 hdr->b_l1hdr.b_byteswap = DMU_BSWAP_UINT64;
6370 hdr->b_l1hdr.b_byteswap =
6371 DMU_OT_BYTESWAP(BP_GET_TYPE(bp));
6374 hdr->b_l1hdr.b_byteswap = DMU_BSWAP_NUMFUNCS;
6377 arc_hdr_set_flags(hdr, ARC_FLAG_PROTECTED);
6378 hdr->b_crypt_hdr.b_ot = BP_GET_TYPE(bp);
6379 hdr->b_crypt_hdr.b_dsobj = zio->io_bookmark.zb_objset;
6380 zio_crypt_decode_params_bp(bp, hdr->b_crypt_hdr.b_salt,
6381 hdr->b_crypt_hdr.b_iv);
6382 zio_crypt_decode_mac_bp(bp, hdr->b_crypt_hdr.b_mac);
6384 arc_hdr_clear_flags(hdr, ARC_FLAG_PROTECTED);
6388 * If this block was written for raw encryption but the zio layer
6389 * ended up only authenticating it, adjust the buffer flags now.
6391 if (BP_IS_AUTHENTICATED(bp) && ARC_BUF_ENCRYPTED(buf)) {
6392 arc_hdr_set_flags(hdr, ARC_FLAG_NOAUTH);
6393 buf->b_flags &= ~ARC_BUF_FLAG_ENCRYPTED;
6394 if (BP_GET_COMPRESS(bp) == ZIO_COMPRESS_OFF)
6395 buf->b_flags &= ~ARC_BUF_FLAG_COMPRESSED;
6396 } else if (BP_IS_HOLE(bp) && ARC_BUF_ENCRYPTED(buf)) {
6397 buf->b_flags &= ~ARC_BUF_FLAG_ENCRYPTED;
6398 buf->b_flags &= ~ARC_BUF_FLAG_COMPRESSED;
6401 /* this must be done after the buffer flags are adjusted */
6402 arc_cksum_compute(buf);
6404 enum zio_compress compress;
6405 if (BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp)) {
6406 compress = ZIO_COMPRESS_OFF;
6408 ASSERT3U(HDR_GET_LSIZE(hdr), ==, BP_GET_LSIZE(bp));
6409 compress = BP_GET_COMPRESS(bp);
6411 HDR_SET_PSIZE(hdr, psize);
6412 arc_hdr_set_compress(hdr, compress);
6413 hdr->b_complevel = zio->io_prop.zp_complevel;
6415 if (zio->io_error != 0 || psize == 0)
6419 * Fill the hdr with data. If the buffer is encrypted we have no choice
6420 * but to copy the data into b_radb. If the hdr is compressed, the data
6421 * we want is available from the zio, otherwise we can take it from
6424 * We might be able to share the buf's data with the hdr here. However,
6425 * doing so would cause the ARC to be full of linear ABDs if we write a
6426 * lot of shareable data. As a compromise, we check whether scattered
6427 * ABDs are allowed, and assume that if they are then the user wants
6428 * the ARC to be primarily filled with them regardless of the data being
6429 * written. Therefore, if they're allowed then we allocate one and copy
6430 * the data into it; otherwise, we share the data directly if we can.
6432 if (ARC_BUF_ENCRYPTED(buf)) {
6433 ASSERT3U(psize, >, 0);
6434 ASSERT(ARC_BUF_COMPRESSED(buf));
6435 arc_hdr_alloc_abd(hdr, ARC_HDR_ALLOC_RDATA |
6436 ARC_HDR_USE_RESERVE);
6437 abd_copy(hdr->b_crypt_hdr.b_rabd, zio->io_abd, psize);
6438 } else if (!(HDR_UNCACHED(hdr) ||
6439 abd_size_alloc_linear(arc_buf_size(buf))) ||
6440 !arc_can_share(hdr, buf)) {
6442 * Ideally, we would always copy the io_abd into b_pabd, but the
6443 * user may have disabled compressed ARC, thus we must check the
6444 * hdr's compression setting rather than the io_bp's.
6446 if (BP_IS_ENCRYPTED(bp)) {
6447 ASSERT3U(psize, >, 0);
6448 arc_hdr_alloc_abd(hdr, ARC_HDR_ALLOC_RDATA |
6449 ARC_HDR_USE_RESERVE);
6450 abd_copy(hdr->b_crypt_hdr.b_rabd, zio->io_abd, psize);
6451 } else if (arc_hdr_get_compress(hdr) != ZIO_COMPRESS_OFF &&
6452 !ARC_BUF_COMPRESSED(buf)) {
6453 ASSERT3U(psize, >, 0);
6454 arc_hdr_alloc_abd(hdr, ARC_HDR_USE_RESERVE);
6455 abd_copy(hdr->b_l1hdr.b_pabd, zio->io_abd, psize);
6457 ASSERT3U(zio->io_orig_size, ==, arc_hdr_size(hdr));
6458 arc_hdr_alloc_abd(hdr, ARC_HDR_USE_RESERVE);
6459 abd_copy_from_buf(hdr->b_l1hdr.b_pabd, buf->b_data,
6463 ASSERT3P(buf->b_data, ==, abd_to_buf(zio->io_orig_abd));
6464 ASSERT3U(zio->io_orig_size, ==, arc_buf_size(buf));
6465 ASSERT3P(hdr->b_l1hdr.b_buf, ==, buf);
6466 ASSERT(ARC_BUF_LAST(buf));
6468 arc_share_buf(hdr, buf);
6472 arc_hdr_verify(hdr, bp);
6473 spl_fstrans_unmark(cookie);
6477 arc_write_children_ready(zio_t *zio)
6479 arc_write_callback_t *callback = zio->io_private;
6480 arc_buf_t *buf = callback->awcb_buf;
6482 callback->awcb_children_ready(zio, buf, callback->awcb_private);
6486 arc_write_done(zio_t *zio)
6488 arc_write_callback_t *callback = zio->io_private;
6489 arc_buf_t *buf = callback->awcb_buf;
6490 arc_buf_hdr_t *hdr = buf->b_hdr;
6492 ASSERT3P(hdr->b_l1hdr.b_acb, ==, NULL);
6494 if (zio->io_error == 0) {
6495 arc_hdr_verify(hdr, zio->io_bp);
6497 if (BP_IS_HOLE(zio->io_bp) || BP_IS_EMBEDDED(zio->io_bp)) {
6498 buf_discard_identity(hdr);
6500 hdr->b_dva = *BP_IDENTITY(zio->io_bp);
6501 hdr->b_birth = BP_PHYSICAL_BIRTH(zio->io_bp);
6504 ASSERT(HDR_EMPTY(hdr));
6508 * If the block to be written was all-zero or compressed enough to be
6509 * embedded in the BP, no write was performed so there will be no
6510 * dva/birth/checksum. The buffer must therefore remain anonymous
6513 if (!HDR_EMPTY(hdr)) {
6514 arc_buf_hdr_t *exists;
6515 kmutex_t *hash_lock;
6517 ASSERT3U(zio->io_error, ==, 0);
6519 arc_cksum_verify(buf);
6521 exists = buf_hash_insert(hdr, &hash_lock);
6522 if (exists != NULL) {
6524 * This can only happen if we overwrite for
6525 * sync-to-convergence, because we remove
6526 * buffers from the hash table when we arc_free().
6528 if (zio->io_flags & ZIO_FLAG_IO_REWRITE) {
6529 if (!BP_EQUAL(&zio->io_bp_orig, zio->io_bp))
6530 panic("bad overwrite, hdr=%p exists=%p",
6531 (void *)hdr, (void *)exists);
6532 ASSERT(zfs_refcount_is_zero(
6533 &exists->b_l1hdr.b_refcnt));
6534 arc_change_state(arc_anon, exists);
6535 arc_hdr_destroy(exists);
6536 mutex_exit(hash_lock);
6537 exists = buf_hash_insert(hdr, &hash_lock);
6538 ASSERT3P(exists, ==, NULL);
6539 } else if (zio->io_flags & ZIO_FLAG_NOPWRITE) {
6541 ASSERT(zio->io_prop.zp_nopwrite);
6542 if (!BP_EQUAL(&zio->io_bp_orig, zio->io_bp))
6543 panic("bad nopwrite, hdr=%p exists=%p",
6544 (void *)hdr, (void *)exists);
6547 ASSERT3P(hdr->b_l1hdr.b_buf, !=, NULL);
6548 ASSERT(ARC_BUF_LAST(hdr->b_l1hdr.b_buf));
6549 ASSERT(hdr->b_l1hdr.b_state == arc_anon);
6550 ASSERT(BP_GET_DEDUP(zio->io_bp));
6551 ASSERT(BP_GET_LEVEL(zio->io_bp) == 0);
6554 arc_hdr_clear_flags(hdr, ARC_FLAG_IO_IN_PROGRESS);
6555 VERIFY3S(remove_reference(hdr, hdr), >, 0);
6556 /* if it's not anon, we are doing a scrub */
6557 if (exists == NULL && hdr->b_l1hdr.b_state == arc_anon)
6558 arc_access(hdr, 0, B_FALSE);
6559 mutex_exit(hash_lock);
6561 arc_hdr_clear_flags(hdr, ARC_FLAG_IO_IN_PROGRESS);
6562 VERIFY3S(remove_reference(hdr, hdr), >, 0);
6565 callback->awcb_done(zio, buf, callback->awcb_private);
6567 abd_free(zio->io_abd);
6568 kmem_free(callback, sizeof (arc_write_callback_t));
6572 arc_write(zio_t *pio, spa_t *spa, uint64_t txg,
6573 blkptr_t *bp, arc_buf_t *buf, boolean_t uncached, boolean_t l2arc,
6574 const zio_prop_t *zp, arc_write_done_func_t *ready,
6575 arc_write_done_func_t *children_ready, arc_write_done_func_t *done,
6576 void *private, zio_priority_t priority, int zio_flags,
6577 const zbookmark_phys_t *zb)
6579 arc_buf_hdr_t *hdr = buf->b_hdr;
6580 arc_write_callback_t *callback;
6582 zio_prop_t localprop = *zp;
6584 ASSERT3P(ready, !=, NULL);
6585 ASSERT3P(done, !=, NULL);
6586 ASSERT(!HDR_IO_ERROR(hdr));
6587 ASSERT(!HDR_IO_IN_PROGRESS(hdr));
6588 ASSERT3P(hdr->b_l1hdr.b_acb, ==, NULL);
6589 ASSERT3P(hdr->b_l1hdr.b_buf, !=, NULL);
6591 arc_hdr_set_flags(hdr, ARC_FLAG_UNCACHED);
6593 arc_hdr_set_flags(hdr, ARC_FLAG_L2CACHE);
6595 if (ARC_BUF_ENCRYPTED(buf)) {
6596 ASSERT(ARC_BUF_COMPRESSED(buf));
6597 localprop.zp_encrypt = B_TRUE;
6598 localprop.zp_compress = HDR_GET_COMPRESS(hdr);
6599 localprop.zp_complevel = hdr->b_complevel;
6600 localprop.zp_byteorder =
6601 (hdr->b_l1hdr.b_byteswap == DMU_BSWAP_NUMFUNCS) ?
6602 ZFS_HOST_BYTEORDER : !ZFS_HOST_BYTEORDER;
6603 memcpy(localprop.zp_salt, hdr->b_crypt_hdr.b_salt,
6605 memcpy(localprop.zp_iv, hdr->b_crypt_hdr.b_iv,
6607 memcpy(localprop.zp_mac, hdr->b_crypt_hdr.b_mac,
6609 if (DMU_OT_IS_ENCRYPTED(localprop.zp_type)) {
6610 localprop.zp_nopwrite = B_FALSE;
6611 localprop.zp_copies =
6612 MIN(localprop.zp_copies, SPA_DVAS_PER_BP - 1);
6614 zio_flags |= ZIO_FLAG_RAW;
6615 } else if (ARC_BUF_COMPRESSED(buf)) {
6616 ASSERT3U(HDR_GET_LSIZE(hdr), !=, arc_buf_size(buf));
6617 localprop.zp_compress = HDR_GET_COMPRESS(hdr);
6618 localprop.zp_complevel = hdr->b_complevel;
6619 zio_flags |= ZIO_FLAG_RAW_COMPRESS;
6621 callback = kmem_zalloc(sizeof (arc_write_callback_t), KM_SLEEP);
6622 callback->awcb_ready = ready;
6623 callback->awcb_children_ready = children_ready;
6624 callback->awcb_done = done;
6625 callback->awcb_private = private;
6626 callback->awcb_buf = buf;
6629 * The hdr's b_pabd is now stale, free it now. A new data block
6630 * will be allocated when the zio pipeline calls arc_write_ready().
6632 if (hdr->b_l1hdr.b_pabd != NULL) {
6634 * If the buf is currently sharing the data block with
6635 * the hdr then we need to break that relationship here.
6636 * The hdr will remain with a NULL data pointer and the
6637 * buf will take sole ownership of the block.
6639 if (arc_buf_is_shared(buf)) {
6640 arc_unshare_buf(hdr, buf);
6642 arc_hdr_free_abd(hdr, B_FALSE);
6644 VERIFY3P(buf->b_data, !=, NULL);
6647 if (HDR_HAS_RABD(hdr))
6648 arc_hdr_free_abd(hdr, B_TRUE);
6650 if (!(zio_flags & ZIO_FLAG_RAW))
6651 arc_hdr_set_compress(hdr, ZIO_COMPRESS_OFF);
6653 ASSERT(!arc_buf_is_shared(buf));
6654 ASSERT3P(hdr->b_l1hdr.b_pabd, ==, NULL);
6656 zio = zio_write(pio, spa, txg, bp,
6657 abd_get_from_buf(buf->b_data, HDR_GET_LSIZE(hdr)),
6658 HDR_GET_LSIZE(hdr), arc_buf_size(buf), &localprop, arc_write_ready,
6659 (children_ready != NULL) ? arc_write_children_ready : NULL,
6660 arc_write_done, callback, priority, zio_flags, zb);
6666 arc_tempreserve_clear(uint64_t reserve)
6668 atomic_add_64(&arc_tempreserve, -reserve);
6669 ASSERT((int64_t)arc_tempreserve >= 0);
6673 arc_tempreserve_space(spa_t *spa, uint64_t reserve, uint64_t txg)
6679 reserve > arc_c/4 &&
6680 reserve * 4 > (2ULL << SPA_MAXBLOCKSHIFT))
6681 arc_c = MIN(arc_c_max, reserve * 4);
6684 * Throttle when the calculated memory footprint for the TXG
6685 * exceeds the target ARC size.
6687 if (reserve > arc_c) {
6688 DMU_TX_STAT_BUMP(dmu_tx_memory_reserve);
6689 return (SET_ERROR(ERESTART));
6693 * Don't count loaned bufs as in flight dirty data to prevent long
6694 * network delays from blocking transactions that are ready to be
6695 * assigned to a txg.
6698 /* assert that it has not wrapped around */
6699 ASSERT3S(atomic_add_64_nv(&arc_loaned_bytes, 0), >=, 0);
6701 anon_size = MAX((int64_t)
6702 (zfs_refcount_count(&arc_anon->arcs_size[ARC_BUFC_DATA]) +
6703 zfs_refcount_count(&arc_anon->arcs_size[ARC_BUFC_METADATA]) -
6704 arc_loaned_bytes), 0);
6707 * Writes will, almost always, require additional memory allocations
6708 * in order to compress/encrypt/etc the data. We therefore need to
6709 * make sure that there is sufficient available memory for this.
6711 error = arc_memory_throttle(spa, reserve, txg);
6716 * Throttle writes when the amount of dirty data in the cache
6717 * gets too large. We try to keep the cache less than half full
6718 * of dirty blocks so that our sync times don't grow too large.
6720 * In the case of one pool being built on another pool, we want
6721 * to make sure we don't end up throttling the lower (backing)
6722 * pool when the upper pool is the majority contributor to dirty
6723 * data. To insure we make forward progress during throttling, we
6724 * also check the current pool's net dirty data and only throttle
6725 * if it exceeds zfs_arc_pool_dirty_percent of the anonymous dirty
6726 * data in the cache.
6728 * Note: if two requests come in concurrently, we might let them
6729 * both succeed, when one of them should fail. Not a huge deal.
6731 uint64_t total_dirty = reserve + arc_tempreserve + anon_size;
6732 uint64_t spa_dirty_anon = spa_dirty_data(spa);
6733 uint64_t rarc_c = arc_warm ? arc_c : arc_c_max;
6734 if (total_dirty > rarc_c * zfs_arc_dirty_limit_percent / 100 &&
6735 anon_size > rarc_c * zfs_arc_anon_limit_percent / 100 &&
6736 spa_dirty_anon > anon_size * zfs_arc_pool_dirty_percent / 100) {
6738 uint64_t meta_esize = zfs_refcount_count(
6739 &arc_anon->arcs_esize[ARC_BUFC_METADATA]);
6740 uint64_t data_esize =
6741 zfs_refcount_count(&arc_anon->arcs_esize[ARC_BUFC_DATA]);
6742 dprintf("failing, arc_tempreserve=%lluK anon_meta=%lluK "
6743 "anon_data=%lluK tempreserve=%lluK rarc_c=%lluK\n",
6744 (u_longlong_t)arc_tempreserve >> 10,
6745 (u_longlong_t)meta_esize >> 10,
6746 (u_longlong_t)data_esize >> 10,
6747 (u_longlong_t)reserve >> 10,
6748 (u_longlong_t)rarc_c >> 10);
6750 DMU_TX_STAT_BUMP(dmu_tx_dirty_throttle);
6751 return (SET_ERROR(ERESTART));
6753 atomic_add_64(&arc_tempreserve, reserve);
6758 arc_kstat_update_state(arc_state_t *state, kstat_named_t *size,
6759 kstat_named_t *data, kstat_named_t *metadata,
6760 kstat_named_t *evict_data, kstat_named_t *evict_metadata)
6763 zfs_refcount_count(&state->arcs_size[ARC_BUFC_DATA]);
6764 metadata->value.ui64 =
6765 zfs_refcount_count(&state->arcs_size[ARC_BUFC_METADATA]);
6766 size->value.ui64 = data->value.ui64 + metadata->value.ui64;
6767 evict_data->value.ui64 =
6768 zfs_refcount_count(&state->arcs_esize[ARC_BUFC_DATA]);
6769 evict_metadata->value.ui64 =
6770 zfs_refcount_count(&state->arcs_esize[ARC_BUFC_METADATA]);
6774 arc_kstat_update(kstat_t *ksp, int rw)
6776 arc_stats_t *as = ksp->ks_data;
6778 if (rw == KSTAT_WRITE)
6779 return (SET_ERROR(EACCES));
6781 as->arcstat_hits.value.ui64 =
6782 wmsum_value(&arc_sums.arcstat_hits);
6783 as->arcstat_iohits.value.ui64 =
6784 wmsum_value(&arc_sums.arcstat_iohits);
6785 as->arcstat_misses.value.ui64 =
6786 wmsum_value(&arc_sums.arcstat_misses);
6787 as->arcstat_demand_data_hits.value.ui64 =
6788 wmsum_value(&arc_sums.arcstat_demand_data_hits);
6789 as->arcstat_demand_data_iohits.value.ui64 =
6790 wmsum_value(&arc_sums.arcstat_demand_data_iohits);
6791 as->arcstat_demand_data_misses.value.ui64 =
6792 wmsum_value(&arc_sums.arcstat_demand_data_misses);
6793 as->arcstat_demand_metadata_hits.value.ui64 =
6794 wmsum_value(&arc_sums.arcstat_demand_metadata_hits);
6795 as->arcstat_demand_metadata_iohits.value.ui64 =
6796 wmsum_value(&arc_sums.arcstat_demand_metadata_iohits);
6797 as->arcstat_demand_metadata_misses.value.ui64 =
6798 wmsum_value(&arc_sums.arcstat_demand_metadata_misses);
6799 as->arcstat_prefetch_data_hits.value.ui64 =
6800 wmsum_value(&arc_sums.arcstat_prefetch_data_hits);
6801 as->arcstat_prefetch_data_iohits.value.ui64 =
6802 wmsum_value(&arc_sums.arcstat_prefetch_data_iohits);
6803 as->arcstat_prefetch_data_misses.value.ui64 =
6804 wmsum_value(&arc_sums.arcstat_prefetch_data_misses);
6805 as->arcstat_prefetch_metadata_hits.value.ui64 =
6806 wmsum_value(&arc_sums.arcstat_prefetch_metadata_hits);
6807 as->arcstat_prefetch_metadata_iohits.value.ui64 =
6808 wmsum_value(&arc_sums.arcstat_prefetch_metadata_iohits);
6809 as->arcstat_prefetch_metadata_misses.value.ui64 =
6810 wmsum_value(&arc_sums.arcstat_prefetch_metadata_misses);
6811 as->arcstat_mru_hits.value.ui64 =
6812 wmsum_value(&arc_sums.arcstat_mru_hits);
6813 as->arcstat_mru_ghost_hits.value.ui64 =
6814 wmsum_value(&arc_sums.arcstat_mru_ghost_hits);
6815 as->arcstat_mfu_hits.value.ui64 =
6816 wmsum_value(&arc_sums.arcstat_mfu_hits);
6817 as->arcstat_mfu_ghost_hits.value.ui64 =
6818 wmsum_value(&arc_sums.arcstat_mfu_ghost_hits);
6819 as->arcstat_uncached_hits.value.ui64 =
6820 wmsum_value(&arc_sums.arcstat_uncached_hits);
6821 as->arcstat_deleted.value.ui64 =
6822 wmsum_value(&arc_sums.arcstat_deleted);
6823 as->arcstat_mutex_miss.value.ui64 =
6824 wmsum_value(&arc_sums.arcstat_mutex_miss);
6825 as->arcstat_access_skip.value.ui64 =
6826 wmsum_value(&arc_sums.arcstat_access_skip);
6827 as->arcstat_evict_skip.value.ui64 =
6828 wmsum_value(&arc_sums.arcstat_evict_skip);
6829 as->arcstat_evict_not_enough.value.ui64 =
6830 wmsum_value(&arc_sums.arcstat_evict_not_enough);
6831 as->arcstat_evict_l2_cached.value.ui64 =
6832 wmsum_value(&arc_sums.arcstat_evict_l2_cached);
6833 as->arcstat_evict_l2_eligible.value.ui64 =
6834 wmsum_value(&arc_sums.arcstat_evict_l2_eligible);
6835 as->arcstat_evict_l2_eligible_mfu.value.ui64 =
6836 wmsum_value(&arc_sums.arcstat_evict_l2_eligible_mfu);
6837 as->arcstat_evict_l2_eligible_mru.value.ui64 =
6838 wmsum_value(&arc_sums.arcstat_evict_l2_eligible_mru);
6839 as->arcstat_evict_l2_ineligible.value.ui64 =
6840 wmsum_value(&arc_sums.arcstat_evict_l2_ineligible);
6841 as->arcstat_evict_l2_skip.value.ui64 =
6842 wmsum_value(&arc_sums.arcstat_evict_l2_skip);
6843 as->arcstat_hash_collisions.value.ui64 =
6844 wmsum_value(&arc_sums.arcstat_hash_collisions);
6845 as->arcstat_hash_chains.value.ui64 =
6846 wmsum_value(&arc_sums.arcstat_hash_chains);
6847 as->arcstat_size.value.ui64 =
6848 aggsum_value(&arc_sums.arcstat_size);
6849 as->arcstat_compressed_size.value.ui64 =
6850 wmsum_value(&arc_sums.arcstat_compressed_size);
6851 as->arcstat_uncompressed_size.value.ui64 =
6852 wmsum_value(&arc_sums.arcstat_uncompressed_size);
6853 as->arcstat_overhead_size.value.ui64 =
6854 wmsum_value(&arc_sums.arcstat_overhead_size);
6855 as->arcstat_hdr_size.value.ui64 =
6856 wmsum_value(&arc_sums.arcstat_hdr_size);
6857 as->arcstat_data_size.value.ui64 =
6858 wmsum_value(&arc_sums.arcstat_data_size);
6859 as->arcstat_metadata_size.value.ui64 =
6860 wmsum_value(&arc_sums.arcstat_metadata_size);
6861 as->arcstat_dbuf_size.value.ui64 =
6862 wmsum_value(&arc_sums.arcstat_dbuf_size);
6863 #if defined(COMPAT_FREEBSD11)
6864 as->arcstat_other_size.value.ui64 =
6865 wmsum_value(&arc_sums.arcstat_bonus_size) +
6866 wmsum_value(&arc_sums.arcstat_dnode_size) +
6867 wmsum_value(&arc_sums.arcstat_dbuf_size);
6870 arc_kstat_update_state(arc_anon,
6871 &as->arcstat_anon_size,
6872 &as->arcstat_anon_data,
6873 &as->arcstat_anon_metadata,
6874 &as->arcstat_anon_evictable_data,
6875 &as->arcstat_anon_evictable_metadata);
6876 arc_kstat_update_state(arc_mru,
6877 &as->arcstat_mru_size,
6878 &as->arcstat_mru_data,
6879 &as->arcstat_mru_metadata,
6880 &as->arcstat_mru_evictable_data,
6881 &as->arcstat_mru_evictable_metadata);
6882 arc_kstat_update_state(arc_mru_ghost,
6883 &as->arcstat_mru_ghost_size,
6884 &as->arcstat_mru_ghost_data,
6885 &as->arcstat_mru_ghost_metadata,
6886 &as->arcstat_mru_ghost_evictable_data,
6887 &as->arcstat_mru_ghost_evictable_metadata);
6888 arc_kstat_update_state(arc_mfu,
6889 &as->arcstat_mfu_size,
6890 &as->arcstat_mfu_data,
6891 &as->arcstat_mfu_metadata,
6892 &as->arcstat_mfu_evictable_data,
6893 &as->arcstat_mfu_evictable_metadata);
6894 arc_kstat_update_state(arc_mfu_ghost,
6895 &as->arcstat_mfu_ghost_size,
6896 &as->arcstat_mfu_ghost_data,
6897 &as->arcstat_mfu_ghost_metadata,
6898 &as->arcstat_mfu_ghost_evictable_data,
6899 &as->arcstat_mfu_ghost_evictable_metadata);
6900 arc_kstat_update_state(arc_uncached,
6901 &as->arcstat_uncached_size,
6902 &as->arcstat_uncached_data,
6903 &as->arcstat_uncached_metadata,
6904 &as->arcstat_uncached_evictable_data,
6905 &as->arcstat_uncached_evictable_metadata);
6907 as->arcstat_dnode_size.value.ui64 =
6908 wmsum_value(&arc_sums.arcstat_dnode_size);
6909 as->arcstat_bonus_size.value.ui64 =
6910 wmsum_value(&arc_sums.arcstat_bonus_size);
6911 as->arcstat_l2_hits.value.ui64 =
6912 wmsum_value(&arc_sums.arcstat_l2_hits);
6913 as->arcstat_l2_misses.value.ui64 =
6914 wmsum_value(&arc_sums.arcstat_l2_misses);
6915 as->arcstat_l2_prefetch_asize.value.ui64 =
6916 wmsum_value(&arc_sums.arcstat_l2_prefetch_asize);
6917 as->arcstat_l2_mru_asize.value.ui64 =
6918 wmsum_value(&arc_sums.arcstat_l2_mru_asize);
6919 as->arcstat_l2_mfu_asize.value.ui64 =
6920 wmsum_value(&arc_sums.arcstat_l2_mfu_asize);
6921 as->arcstat_l2_bufc_data_asize.value.ui64 =
6922 wmsum_value(&arc_sums.arcstat_l2_bufc_data_asize);
6923 as->arcstat_l2_bufc_metadata_asize.value.ui64 =
6924 wmsum_value(&arc_sums.arcstat_l2_bufc_metadata_asize);
6925 as->arcstat_l2_feeds.value.ui64 =
6926 wmsum_value(&arc_sums.arcstat_l2_feeds);
6927 as->arcstat_l2_rw_clash.value.ui64 =
6928 wmsum_value(&arc_sums.arcstat_l2_rw_clash);
6929 as->arcstat_l2_read_bytes.value.ui64 =
6930 wmsum_value(&arc_sums.arcstat_l2_read_bytes);
6931 as->arcstat_l2_write_bytes.value.ui64 =
6932 wmsum_value(&arc_sums.arcstat_l2_write_bytes);
6933 as->arcstat_l2_writes_sent.value.ui64 =
6934 wmsum_value(&arc_sums.arcstat_l2_writes_sent);
6935 as->arcstat_l2_writes_done.value.ui64 =
6936 wmsum_value(&arc_sums.arcstat_l2_writes_done);
6937 as->arcstat_l2_writes_error.value.ui64 =
6938 wmsum_value(&arc_sums.arcstat_l2_writes_error);
6939 as->arcstat_l2_writes_lock_retry.value.ui64 =
6940 wmsum_value(&arc_sums.arcstat_l2_writes_lock_retry);
6941 as->arcstat_l2_evict_lock_retry.value.ui64 =
6942 wmsum_value(&arc_sums.arcstat_l2_evict_lock_retry);
6943 as->arcstat_l2_evict_reading.value.ui64 =
6944 wmsum_value(&arc_sums.arcstat_l2_evict_reading);
6945 as->arcstat_l2_evict_l1cached.value.ui64 =
6946 wmsum_value(&arc_sums.arcstat_l2_evict_l1cached);
6947 as->arcstat_l2_free_on_write.value.ui64 =
6948 wmsum_value(&arc_sums.arcstat_l2_free_on_write);
6949 as->arcstat_l2_abort_lowmem.value.ui64 =
6950 wmsum_value(&arc_sums.arcstat_l2_abort_lowmem);
6951 as->arcstat_l2_cksum_bad.value.ui64 =
6952 wmsum_value(&arc_sums.arcstat_l2_cksum_bad);
6953 as->arcstat_l2_io_error.value.ui64 =
6954 wmsum_value(&arc_sums.arcstat_l2_io_error);
6955 as->arcstat_l2_lsize.value.ui64 =
6956 wmsum_value(&arc_sums.arcstat_l2_lsize);
6957 as->arcstat_l2_psize.value.ui64 =
6958 wmsum_value(&arc_sums.arcstat_l2_psize);
6959 as->arcstat_l2_hdr_size.value.ui64 =
6960 aggsum_value(&arc_sums.arcstat_l2_hdr_size);
6961 as->arcstat_l2_log_blk_writes.value.ui64 =
6962 wmsum_value(&arc_sums.arcstat_l2_log_blk_writes);
6963 as->arcstat_l2_log_blk_asize.value.ui64 =
6964 wmsum_value(&arc_sums.arcstat_l2_log_blk_asize);
6965 as->arcstat_l2_log_blk_count.value.ui64 =
6966 wmsum_value(&arc_sums.arcstat_l2_log_blk_count);
6967 as->arcstat_l2_rebuild_success.value.ui64 =
6968 wmsum_value(&arc_sums.arcstat_l2_rebuild_success);
6969 as->arcstat_l2_rebuild_abort_unsupported.value.ui64 =
6970 wmsum_value(&arc_sums.arcstat_l2_rebuild_abort_unsupported);
6971 as->arcstat_l2_rebuild_abort_io_errors.value.ui64 =
6972 wmsum_value(&arc_sums.arcstat_l2_rebuild_abort_io_errors);
6973 as->arcstat_l2_rebuild_abort_dh_errors.value.ui64 =
6974 wmsum_value(&arc_sums.arcstat_l2_rebuild_abort_dh_errors);
6975 as->arcstat_l2_rebuild_abort_cksum_lb_errors.value.ui64 =
6976 wmsum_value(&arc_sums.arcstat_l2_rebuild_abort_cksum_lb_errors);
6977 as->arcstat_l2_rebuild_abort_lowmem.value.ui64 =
6978 wmsum_value(&arc_sums.arcstat_l2_rebuild_abort_lowmem);
6979 as->arcstat_l2_rebuild_size.value.ui64 =
6980 wmsum_value(&arc_sums.arcstat_l2_rebuild_size);
6981 as->arcstat_l2_rebuild_asize.value.ui64 =
6982 wmsum_value(&arc_sums.arcstat_l2_rebuild_asize);
6983 as->arcstat_l2_rebuild_bufs.value.ui64 =
6984 wmsum_value(&arc_sums.arcstat_l2_rebuild_bufs);
6985 as->arcstat_l2_rebuild_bufs_precached.value.ui64 =
6986 wmsum_value(&arc_sums.arcstat_l2_rebuild_bufs_precached);
6987 as->arcstat_l2_rebuild_log_blks.value.ui64 =
6988 wmsum_value(&arc_sums.arcstat_l2_rebuild_log_blks);
6989 as->arcstat_memory_throttle_count.value.ui64 =
6990 wmsum_value(&arc_sums.arcstat_memory_throttle_count);
6991 as->arcstat_memory_direct_count.value.ui64 =
6992 wmsum_value(&arc_sums.arcstat_memory_direct_count);
6993 as->arcstat_memory_indirect_count.value.ui64 =
6994 wmsum_value(&arc_sums.arcstat_memory_indirect_count);
6996 as->arcstat_memory_all_bytes.value.ui64 =
6998 as->arcstat_memory_free_bytes.value.ui64 =
7000 as->arcstat_memory_available_bytes.value.i64 =
7001 arc_available_memory();
7003 as->arcstat_prune.value.ui64 =
7004 wmsum_value(&arc_sums.arcstat_prune);
7005 as->arcstat_meta_used.value.ui64 =
7006 wmsum_value(&arc_sums.arcstat_meta_used);
7007 as->arcstat_async_upgrade_sync.value.ui64 =
7008 wmsum_value(&arc_sums.arcstat_async_upgrade_sync);
7009 as->arcstat_predictive_prefetch.value.ui64 =
7010 wmsum_value(&arc_sums.arcstat_predictive_prefetch);
7011 as->arcstat_demand_hit_predictive_prefetch.value.ui64 =
7012 wmsum_value(&arc_sums.arcstat_demand_hit_predictive_prefetch);
7013 as->arcstat_demand_iohit_predictive_prefetch.value.ui64 =
7014 wmsum_value(&arc_sums.arcstat_demand_iohit_predictive_prefetch);
7015 as->arcstat_prescient_prefetch.value.ui64 =
7016 wmsum_value(&arc_sums.arcstat_prescient_prefetch);
7017 as->arcstat_demand_hit_prescient_prefetch.value.ui64 =
7018 wmsum_value(&arc_sums.arcstat_demand_hit_prescient_prefetch);
7019 as->arcstat_demand_iohit_prescient_prefetch.value.ui64 =
7020 wmsum_value(&arc_sums.arcstat_demand_iohit_prescient_prefetch);
7021 as->arcstat_raw_size.value.ui64 =
7022 wmsum_value(&arc_sums.arcstat_raw_size);
7023 as->arcstat_cached_only_in_progress.value.ui64 =
7024 wmsum_value(&arc_sums.arcstat_cached_only_in_progress);
7025 as->arcstat_abd_chunk_waste_size.value.ui64 =
7026 wmsum_value(&arc_sums.arcstat_abd_chunk_waste_size);
7032 * This function *must* return indices evenly distributed between all
7033 * sublists of the multilist. This is needed due to how the ARC eviction
7034 * code is laid out; arc_evict_state() assumes ARC buffers are evenly
7035 * distributed between all sublists and uses this assumption when
7036 * deciding which sublist to evict from and how much to evict from it.
7039 arc_state_multilist_index_func(multilist_t *ml, void *obj)
7041 arc_buf_hdr_t *hdr = obj;
7044 * We rely on b_dva to generate evenly distributed index
7045 * numbers using buf_hash below. So, as an added precaution,
7046 * let's make sure we never add empty buffers to the arc lists.
7048 ASSERT(!HDR_EMPTY(hdr));
7051 * The assumption here, is the hash value for a given
7052 * arc_buf_hdr_t will remain constant throughout its lifetime
7053 * (i.e. its b_spa, b_dva, and b_birth fields don't change).
7054 * Thus, we don't need to store the header's sublist index
7055 * on insertion, as this index can be recalculated on removal.
7057 * Also, the low order bits of the hash value are thought to be
7058 * distributed evenly. Otherwise, in the case that the multilist
7059 * has a power of two number of sublists, each sublists' usage
7060 * would not be evenly distributed. In this context full 64bit
7061 * division would be a waste of time, so limit it to 32 bits.
7063 return ((unsigned int)buf_hash(hdr->b_spa, &hdr->b_dva, hdr->b_birth) %
7064 multilist_get_num_sublists(ml));
7068 arc_state_l2c_multilist_index_func(multilist_t *ml, void *obj)
7070 panic("Header %p insert into arc_l2c_only %p", obj, ml);
7073 #define WARN_IF_TUNING_IGNORED(tuning, value, do_warn) do { \
7074 if ((do_warn) && (tuning) && ((tuning) != (value))) { \
7076 "ignoring tunable %s (using %llu instead)", \
7077 (#tuning), (u_longlong_t)(value)); \
7082 * Called during module initialization and periodically thereafter to
7083 * apply reasonable changes to the exposed performance tunings. Can also be
7084 * called explicitly by param_set_arc_*() functions when ARC tunables are
7085 * updated manually. Non-zero zfs_* values which differ from the currently set
7086 * values will be applied.
7089 arc_tuning_update(boolean_t verbose)
7091 uint64_t allmem = arc_all_memory();
7093 /* Valid range: 32M - <arc_c_max> */
7094 if ((zfs_arc_min) && (zfs_arc_min != arc_c_min) &&
7095 (zfs_arc_min >= 2ULL << SPA_MAXBLOCKSHIFT) &&
7096 (zfs_arc_min <= arc_c_max)) {
7097 arc_c_min = zfs_arc_min;
7098 arc_c = MAX(arc_c, arc_c_min);
7100 WARN_IF_TUNING_IGNORED(zfs_arc_min, arc_c_min, verbose);
7102 /* Valid range: 64M - <all physical memory> */
7103 if ((zfs_arc_max) && (zfs_arc_max != arc_c_max) &&
7104 (zfs_arc_max >= MIN_ARC_MAX) && (zfs_arc_max < allmem) &&
7105 (zfs_arc_max > arc_c_min)) {
7106 arc_c_max = zfs_arc_max;
7107 arc_c = MIN(arc_c, arc_c_max);
7108 if (arc_dnode_limit > arc_c_max)
7109 arc_dnode_limit = arc_c_max;
7111 WARN_IF_TUNING_IGNORED(zfs_arc_max, arc_c_max, verbose);
7113 /* Valid range: 0 - <all physical memory> */
7114 arc_dnode_limit = zfs_arc_dnode_limit ? zfs_arc_dnode_limit :
7115 MIN(zfs_arc_dnode_limit_percent, 100) * arc_c_max / 100;
7116 WARN_IF_TUNING_IGNORED(zfs_arc_dnode_limit, arc_dnode_limit, verbose);
7118 /* Valid range: 1 - N */
7119 if (zfs_arc_grow_retry)
7120 arc_grow_retry = zfs_arc_grow_retry;
7122 /* Valid range: 1 - N */
7123 if (zfs_arc_shrink_shift) {
7124 arc_shrink_shift = zfs_arc_shrink_shift;
7125 arc_no_grow_shift = MIN(arc_no_grow_shift, arc_shrink_shift -1);
7128 /* Valid range: 1 - N ms */
7129 if (zfs_arc_min_prefetch_ms)
7130 arc_min_prefetch_ms = zfs_arc_min_prefetch_ms;
7132 /* Valid range: 1 - N ms */
7133 if (zfs_arc_min_prescient_prefetch_ms) {
7134 arc_min_prescient_prefetch_ms =
7135 zfs_arc_min_prescient_prefetch_ms;
7138 /* Valid range: 0 - 100 */
7139 if (zfs_arc_lotsfree_percent <= 100)
7140 arc_lotsfree_percent = zfs_arc_lotsfree_percent;
7141 WARN_IF_TUNING_IGNORED(zfs_arc_lotsfree_percent, arc_lotsfree_percent,
7144 /* Valid range: 0 - <all physical memory> */
7145 if ((zfs_arc_sys_free) && (zfs_arc_sys_free != arc_sys_free))
7146 arc_sys_free = MIN(zfs_arc_sys_free, allmem);
7147 WARN_IF_TUNING_IGNORED(zfs_arc_sys_free, arc_sys_free, verbose);
7151 arc_state_multilist_init(multilist_t *ml,
7152 multilist_sublist_index_func_t *index_func, int *maxcountp)
7154 multilist_create(ml, sizeof (arc_buf_hdr_t),
7155 offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node), index_func);
7156 *maxcountp = MAX(*maxcountp, multilist_get_num_sublists(ml));
7160 arc_state_init(void)
7162 int num_sublists = 0;
7164 arc_state_multilist_init(&arc_mru->arcs_list[ARC_BUFC_METADATA],
7165 arc_state_multilist_index_func, &num_sublists);
7166 arc_state_multilist_init(&arc_mru->arcs_list[ARC_BUFC_DATA],
7167 arc_state_multilist_index_func, &num_sublists);
7168 arc_state_multilist_init(&arc_mru_ghost->arcs_list[ARC_BUFC_METADATA],
7169 arc_state_multilist_index_func, &num_sublists);
7170 arc_state_multilist_init(&arc_mru_ghost->arcs_list[ARC_BUFC_DATA],
7171 arc_state_multilist_index_func, &num_sublists);
7172 arc_state_multilist_init(&arc_mfu->arcs_list[ARC_BUFC_METADATA],
7173 arc_state_multilist_index_func, &num_sublists);
7174 arc_state_multilist_init(&arc_mfu->arcs_list[ARC_BUFC_DATA],
7175 arc_state_multilist_index_func, &num_sublists);
7176 arc_state_multilist_init(&arc_mfu_ghost->arcs_list[ARC_BUFC_METADATA],
7177 arc_state_multilist_index_func, &num_sublists);
7178 arc_state_multilist_init(&arc_mfu_ghost->arcs_list[ARC_BUFC_DATA],
7179 arc_state_multilist_index_func, &num_sublists);
7180 arc_state_multilist_init(&arc_uncached->arcs_list[ARC_BUFC_METADATA],
7181 arc_state_multilist_index_func, &num_sublists);
7182 arc_state_multilist_init(&arc_uncached->arcs_list[ARC_BUFC_DATA],
7183 arc_state_multilist_index_func, &num_sublists);
7186 * L2 headers should never be on the L2 state list since they don't
7187 * have L1 headers allocated. Special index function asserts that.
7189 arc_state_multilist_init(&arc_l2c_only->arcs_list[ARC_BUFC_METADATA],
7190 arc_state_l2c_multilist_index_func, &num_sublists);
7191 arc_state_multilist_init(&arc_l2c_only->arcs_list[ARC_BUFC_DATA],
7192 arc_state_l2c_multilist_index_func, &num_sublists);
7195 * Keep track of the number of markers needed to reclaim buffers from
7196 * any ARC state. The markers will be pre-allocated so as to minimize
7197 * the number of memory allocations performed by the eviction thread.
7199 arc_state_evict_marker_count = num_sublists;
7201 zfs_refcount_create(&arc_anon->arcs_esize[ARC_BUFC_METADATA]);
7202 zfs_refcount_create(&arc_anon->arcs_esize[ARC_BUFC_DATA]);
7203 zfs_refcount_create(&arc_mru->arcs_esize[ARC_BUFC_METADATA]);
7204 zfs_refcount_create(&arc_mru->arcs_esize[ARC_BUFC_DATA]);
7205 zfs_refcount_create(&arc_mru_ghost->arcs_esize[ARC_BUFC_METADATA]);
7206 zfs_refcount_create(&arc_mru_ghost->arcs_esize[ARC_BUFC_DATA]);
7207 zfs_refcount_create(&arc_mfu->arcs_esize[ARC_BUFC_METADATA]);
7208 zfs_refcount_create(&arc_mfu->arcs_esize[ARC_BUFC_DATA]);
7209 zfs_refcount_create(&arc_mfu_ghost->arcs_esize[ARC_BUFC_METADATA]);
7210 zfs_refcount_create(&arc_mfu_ghost->arcs_esize[ARC_BUFC_DATA]);
7211 zfs_refcount_create(&arc_l2c_only->arcs_esize[ARC_BUFC_METADATA]);
7212 zfs_refcount_create(&arc_l2c_only->arcs_esize[ARC_BUFC_DATA]);
7213 zfs_refcount_create(&arc_uncached->arcs_esize[ARC_BUFC_METADATA]);
7214 zfs_refcount_create(&arc_uncached->arcs_esize[ARC_BUFC_DATA]);
7216 zfs_refcount_create(&arc_anon->arcs_size[ARC_BUFC_DATA]);
7217 zfs_refcount_create(&arc_anon->arcs_size[ARC_BUFC_METADATA]);
7218 zfs_refcount_create(&arc_mru->arcs_size[ARC_BUFC_DATA]);
7219 zfs_refcount_create(&arc_mru->arcs_size[ARC_BUFC_METADATA]);
7220 zfs_refcount_create(&arc_mru_ghost->arcs_size[ARC_BUFC_DATA]);
7221 zfs_refcount_create(&arc_mru_ghost->arcs_size[ARC_BUFC_METADATA]);
7222 zfs_refcount_create(&arc_mfu->arcs_size[ARC_BUFC_DATA]);
7223 zfs_refcount_create(&arc_mfu->arcs_size[ARC_BUFC_METADATA]);
7224 zfs_refcount_create(&arc_mfu_ghost->arcs_size[ARC_BUFC_DATA]);
7225 zfs_refcount_create(&arc_mfu_ghost->arcs_size[ARC_BUFC_METADATA]);
7226 zfs_refcount_create(&arc_l2c_only->arcs_size[ARC_BUFC_DATA]);
7227 zfs_refcount_create(&arc_l2c_only->arcs_size[ARC_BUFC_METADATA]);
7228 zfs_refcount_create(&arc_uncached->arcs_size[ARC_BUFC_DATA]);
7229 zfs_refcount_create(&arc_uncached->arcs_size[ARC_BUFC_METADATA]);
7231 wmsum_init(&arc_mru_ghost->arcs_hits[ARC_BUFC_DATA], 0);
7232 wmsum_init(&arc_mru_ghost->arcs_hits[ARC_BUFC_METADATA], 0);
7233 wmsum_init(&arc_mfu_ghost->arcs_hits[ARC_BUFC_DATA], 0);
7234 wmsum_init(&arc_mfu_ghost->arcs_hits[ARC_BUFC_METADATA], 0);
7236 wmsum_init(&arc_sums.arcstat_hits, 0);
7237 wmsum_init(&arc_sums.arcstat_iohits, 0);
7238 wmsum_init(&arc_sums.arcstat_misses, 0);
7239 wmsum_init(&arc_sums.arcstat_demand_data_hits, 0);
7240 wmsum_init(&arc_sums.arcstat_demand_data_iohits, 0);
7241 wmsum_init(&arc_sums.arcstat_demand_data_misses, 0);
7242 wmsum_init(&arc_sums.arcstat_demand_metadata_hits, 0);
7243 wmsum_init(&arc_sums.arcstat_demand_metadata_iohits, 0);
7244 wmsum_init(&arc_sums.arcstat_demand_metadata_misses, 0);
7245 wmsum_init(&arc_sums.arcstat_prefetch_data_hits, 0);
7246 wmsum_init(&arc_sums.arcstat_prefetch_data_iohits, 0);
7247 wmsum_init(&arc_sums.arcstat_prefetch_data_misses, 0);
7248 wmsum_init(&arc_sums.arcstat_prefetch_metadata_hits, 0);
7249 wmsum_init(&arc_sums.arcstat_prefetch_metadata_iohits, 0);
7250 wmsum_init(&arc_sums.arcstat_prefetch_metadata_misses, 0);
7251 wmsum_init(&arc_sums.arcstat_mru_hits, 0);
7252 wmsum_init(&arc_sums.arcstat_mru_ghost_hits, 0);
7253 wmsum_init(&arc_sums.arcstat_mfu_hits, 0);
7254 wmsum_init(&arc_sums.arcstat_mfu_ghost_hits, 0);
7255 wmsum_init(&arc_sums.arcstat_uncached_hits, 0);
7256 wmsum_init(&arc_sums.arcstat_deleted, 0);
7257 wmsum_init(&arc_sums.arcstat_mutex_miss, 0);
7258 wmsum_init(&arc_sums.arcstat_access_skip, 0);
7259 wmsum_init(&arc_sums.arcstat_evict_skip, 0);
7260 wmsum_init(&arc_sums.arcstat_evict_not_enough, 0);
7261 wmsum_init(&arc_sums.arcstat_evict_l2_cached, 0);
7262 wmsum_init(&arc_sums.arcstat_evict_l2_eligible, 0);
7263 wmsum_init(&arc_sums.arcstat_evict_l2_eligible_mfu, 0);
7264 wmsum_init(&arc_sums.arcstat_evict_l2_eligible_mru, 0);
7265 wmsum_init(&arc_sums.arcstat_evict_l2_ineligible, 0);
7266 wmsum_init(&arc_sums.arcstat_evict_l2_skip, 0);
7267 wmsum_init(&arc_sums.arcstat_hash_collisions, 0);
7268 wmsum_init(&arc_sums.arcstat_hash_chains, 0);
7269 aggsum_init(&arc_sums.arcstat_size, 0);
7270 wmsum_init(&arc_sums.arcstat_compressed_size, 0);
7271 wmsum_init(&arc_sums.arcstat_uncompressed_size, 0);
7272 wmsum_init(&arc_sums.arcstat_overhead_size, 0);
7273 wmsum_init(&arc_sums.arcstat_hdr_size, 0);
7274 wmsum_init(&arc_sums.arcstat_data_size, 0);
7275 wmsum_init(&arc_sums.arcstat_metadata_size, 0);
7276 wmsum_init(&arc_sums.arcstat_dbuf_size, 0);
7277 wmsum_init(&arc_sums.arcstat_dnode_size, 0);
7278 wmsum_init(&arc_sums.arcstat_bonus_size, 0);
7279 wmsum_init(&arc_sums.arcstat_l2_hits, 0);
7280 wmsum_init(&arc_sums.arcstat_l2_misses, 0);
7281 wmsum_init(&arc_sums.arcstat_l2_prefetch_asize, 0);
7282 wmsum_init(&arc_sums.arcstat_l2_mru_asize, 0);
7283 wmsum_init(&arc_sums.arcstat_l2_mfu_asize, 0);
7284 wmsum_init(&arc_sums.arcstat_l2_bufc_data_asize, 0);
7285 wmsum_init(&arc_sums.arcstat_l2_bufc_metadata_asize, 0);
7286 wmsum_init(&arc_sums.arcstat_l2_feeds, 0);
7287 wmsum_init(&arc_sums.arcstat_l2_rw_clash, 0);
7288 wmsum_init(&arc_sums.arcstat_l2_read_bytes, 0);
7289 wmsum_init(&arc_sums.arcstat_l2_write_bytes, 0);
7290 wmsum_init(&arc_sums.arcstat_l2_writes_sent, 0);
7291 wmsum_init(&arc_sums.arcstat_l2_writes_done, 0);
7292 wmsum_init(&arc_sums.arcstat_l2_writes_error, 0);
7293 wmsum_init(&arc_sums.arcstat_l2_writes_lock_retry, 0);
7294 wmsum_init(&arc_sums.arcstat_l2_evict_lock_retry, 0);
7295 wmsum_init(&arc_sums.arcstat_l2_evict_reading, 0);
7296 wmsum_init(&arc_sums.arcstat_l2_evict_l1cached, 0);
7297 wmsum_init(&arc_sums.arcstat_l2_free_on_write, 0);
7298 wmsum_init(&arc_sums.arcstat_l2_abort_lowmem, 0);
7299 wmsum_init(&arc_sums.arcstat_l2_cksum_bad, 0);
7300 wmsum_init(&arc_sums.arcstat_l2_io_error, 0);
7301 wmsum_init(&arc_sums.arcstat_l2_lsize, 0);
7302 wmsum_init(&arc_sums.arcstat_l2_psize, 0);
7303 aggsum_init(&arc_sums.arcstat_l2_hdr_size, 0);
7304 wmsum_init(&arc_sums.arcstat_l2_log_blk_writes, 0);
7305 wmsum_init(&arc_sums.arcstat_l2_log_blk_asize, 0);
7306 wmsum_init(&arc_sums.arcstat_l2_log_blk_count, 0);
7307 wmsum_init(&arc_sums.arcstat_l2_rebuild_success, 0);
7308 wmsum_init(&arc_sums.arcstat_l2_rebuild_abort_unsupported, 0);
7309 wmsum_init(&arc_sums.arcstat_l2_rebuild_abort_io_errors, 0);
7310 wmsum_init(&arc_sums.arcstat_l2_rebuild_abort_dh_errors, 0);
7311 wmsum_init(&arc_sums.arcstat_l2_rebuild_abort_cksum_lb_errors, 0);
7312 wmsum_init(&arc_sums.arcstat_l2_rebuild_abort_lowmem, 0);
7313 wmsum_init(&arc_sums.arcstat_l2_rebuild_size, 0);
7314 wmsum_init(&arc_sums.arcstat_l2_rebuild_asize, 0);
7315 wmsum_init(&arc_sums.arcstat_l2_rebuild_bufs, 0);
7316 wmsum_init(&arc_sums.arcstat_l2_rebuild_bufs_precached, 0);
7317 wmsum_init(&arc_sums.arcstat_l2_rebuild_log_blks, 0);
7318 wmsum_init(&arc_sums.arcstat_memory_throttle_count, 0);
7319 wmsum_init(&arc_sums.arcstat_memory_direct_count, 0);
7320 wmsum_init(&arc_sums.arcstat_memory_indirect_count, 0);
7321 wmsum_init(&arc_sums.arcstat_prune, 0);
7322 wmsum_init(&arc_sums.arcstat_meta_used, 0);
7323 wmsum_init(&arc_sums.arcstat_async_upgrade_sync, 0);
7324 wmsum_init(&arc_sums.arcstat_predictive_prefetch, 0);
7325 wmsum_init(&arc_sums.arcstat_demand_hit_predictive_prefetch, 0);
7326 wmsum_init(&arc_sums.arcstat_demand_iohit_predictive_prefetch, 0);
7327 wmsum_init(&arc_sums.arcstat_prescient_prefetch, 0);
7328 wmsum_init(&arc_sums.arcstat_demand_hit_prescient_prefetch, 0);
7329 wmsum_init(&arc_sums.arcstat_demand_iohit_prescient_prefetch, 0);
7330 wmsum_init(&arc_sums.arcstat_raw_size, 0);
7331 wmsum_init(&arc_sums.arcstat_cached_only_in_progress, 0);
7332 wmsum_init(&arc_sums.arcstat_abd_chunk_waste_size, 0);
7334 arc_anon->arcs_state = ARC_STATE_ANON;
7335 arc_mru->arcs_state = ARC_STATE_MRU;
7336 arc_mru_ghost->arcs_state = ARC_STATE_MRU_GHOST;
7337 arc_mfu->arcs_state = ARC_STATE_MFU;
7338 arc_mfu_ghost->arcs_state = ARC_STATE_MFU_GHOST;
7339 arc_l2c_only->arcs_state = ARC_STATE_L2C_ONLY;
7340 arc_uncached->arcs_state = ARC_STATE_UNCACHED;
7344 arc_state_fini(void)
7346 zfs_refcount_destroy(&arc_anon->arcs_esize[ARC_BUFC_METADATA]);
7347 zfs_refcount_destroy(&arc_anon->arcs_esize[ARC_BUFC_DATA]);
7348 zfs_refcount_destroy(&arc_mru->arcs_esize[ARC_BUFC_METADATA]);
7349 zfs_refcount_destroy(&arc_mru->arcs_esize[ARC_BUFC_DATA]);
7350 zfs_refcount_destroy(&arc_mru_ghost->arcs_esize[ARC_BUFC_METADATA]);
7351 zfs_refcount_destroy(&arc_mru_ghost->arcs_esize[ARC_BUFC_DATA]);
7352 zfs_refcount_destroy(&arc_mfu->arcs_esize[ARC_BUFC_METADATA]);
7353 zfs_refcount_destroy(&arc_mfu->arcs_esize[ARC_BUFC_DATA]);
7354 zfs_refcount_destroy(&arc_mfu_ghost->arcs_esize[ARC_BUFC_METADATA]);
7355 zfs_refcount_destroy(&arc_mfu_ghost->arcs_esize[ARC_BUFC_DATA]);
7356 zfs_refcount_destroy(&arc_l2c_only->arcs_esize[ARC_BUFC_METADATA]);
7357 zfs_refcount_destroy(&arc_l2c_only->arcs_esize[ARC_BUFC_DATA]);
7358 zfs_refcount_destroy(&arc_uncached->arcs_esize[ARC_BUFC_METADATA]);
7359 zfs_refcount_destroy(&arc_uncached->arcs_esize[ARC_BUFC_DATA]);
7361 zfs_refcount_destroy(&arc_anon->arcs_size[ARC_BUFC_DATA]);
7362 zfs_refcount_destroy(&arc_anon->arcs_size[ARC_BUFC_METADATA]);
7363 zfs_refcount_destroy(&arc_mru->arcs_size[ARC_BUFC_DATA]);
7364 zfs_refcount_destroy(&arc_mru->arcs_size[ARC_BUFC_METADATA]);
7365 zfs_refcount_destroy(&arc_mru_ghost->arcs_size[ARC_BUFC_DATA]);
7366 zfs_refcount_destroy(&arc_mru_ghost->arcs_size[ARC_BUFC_METADATA]);
7367 zfs_refcount_destroy(&arc_mfu->arcs_size[ARC_BUFC_DATA]);
7368 zfs_refcount_destroy(&arc_mfu->arcs_size[ARC_BUFC_METADATA]);
7369 zfs_refcount_destroy(&arc_mfu_ghost->arcs_size[ARC_BUFC_DATA]);
7370 zfs_refcount_destroy(&arc_mfu_ghost->arcs_size[ARC_BUFC_METADATA]);
7371 zfs_refcount_destroy(&arc_l2c_only->arcs_size[ARC_BUFC_DATA]);
7372 zfs_refcount_destroy(&arc_l2c_only->arcs_size[ARC_BUFC_METADATA]);
7373 zfs_refcount_destroy(&arc_uncached->arcs_size[ARC_BUFC_DATA]);
7374 zfs_refcount_destroy(&arc_uncached->arcs_size[ARC_BUFC_METADATA]);
7376 multilist_destroy(&arc_mru->arcs_list[ARC_BUFC_METADATA]);
7377 multilist_destroy(&arc_mru_ghost->arcs_list[ARC_BUFC_METADATA]);
7378 multilist_destroy(&arc_mfu->arcs_list[ARC_BUFC_METADATA]);
7379 multilist_destroy(&arc_mfu_ghost->arcs_list[ARC_BUFC_METADATA]);
7380 multilist_destroy(&arc_mru->arcs_list[ARC_BUFC_DATA]);
7381 multilist_destroy(&arc_mru_ghost->arcs_list[ARC_BUFC_DATA]);
7382 multilist_destroy(&arc_mfu->arcs_list[ARC_BUFC_DATA]);
7383 multilist_destroy(&arc_mfu_ghost->arcs_list[ARC_BUFC_DATA]);
7384 multilist_destroy(&arc_l2c_only->arcs_list[ARC_BUFC_METADATA]);
7385 multilist_destroy(&arc_l2c_only->arcs_list[ARC_BUFC_DATA]);
7386 multilist_destroy(&arc_uncached->arcs_list[ARC_BUFC_METADATA]);
7387 multilist_destroy(&arc_uncached->arcs_list[ARC_BUFC_DATA]);
7389 wmsum_fini(&arc_mru_ghost->arcs_hits[ARC_BUFC_DATA]);
7390 wmsum_fini(&arc_mru_ghost->arcs_hits[ARC_BUFC_METADATA]);
7391 wmsum_fini(&arc_mfu_ghost->arcs_hits[ARC_BUFC_DATA]);
7392 wmsum_fini(&arc_mfu_ghost->arcs_hits[ARC_BUFC_METADATA]);
7394 wmsum_fini(&arc_sums.arcstat_hits);
7395 wmsum_fini(&arc_sums.arcstat_iohits);
7396 wmsum_fini(&arc_sums.arcstat_misses);
7397 wmsum_fini(&arc_sums.arcstat_demand_data_hits);
7398 wmsum_fini(&arc_sums.arcstat_demand_data_iohits);
7399 wmsum_fini(&arc_sums.arcstat_demand_data_misses);
7400 wmsum_fini(&arc_sums.arcstat_demand_metadata_hits);
7401 wmsum_fini(&arc_sums.arcstat_demand_metadata_iohits);
7402 wmsum_fini(&arc_sums.arcstat_demand_metadata_misses);
7403 wmsum_fini(&arc_sums.arcstat_prefetch_data_hits);
7404 wmsum_fini(&arc_sums.arcstat_prefetch_data_iohits);
7405 wmsum_fini(&arc_sums.arcstat_prefetch_data_misses);
7406 wmsum_fini(&arc_sums.arcstat_prefetch_metadata_hits);
7407 wmsum_fini(&arc_sums.arcstat_prefetch_metadata_iohits);
7408 wmsum_fini(&arc_sums.arcstat_prefetch_metadata_misses);
7409 wmsum_fini(&arc_sums.arcstat_mru_hits);
7410 wmsum_fini(&arc_sums.arcstat_mru_ghost_hits);
7411 wmsum_fini(&arc_sums.arcstat_mfu_hits);
7412 wmsum_fini(&arc_sums.arcstat_mfu_ghost_hits);
7413 wmsum_fini(&arc_sums.arcstat_uncached_hits);
7414 wmsum_fini(&arc_sums.arcstat_deleted);
7415 wmsum_fini(&arc_sums.arcstat_mutex_miss);
7416 wmsum_fini(&arc_sums.arcstat_access_skip);
7417 wmsum_fini(&arc_sums.arcstat_evict_skip);
7418 wmsum_fini(&arc_sums.arcstat_evict_not_enough);
7419 wmsum_fini(&arc_sums.arcstat_evict_l2_cached);
7420 wmsum_fini(&arc_sums.arcstat_evict_l2_eligible);
7421 wmsum_fini(&arc_sums.arcstat_evict_l2_eligible_mfu);
7422 wmsum_fini(&arc_sums.arcstat_evict_l2_eligible_mru);
7423 wmsum_fini(&arc_sums.arcstat_evict_l2_ineligible);
7424 wmsum_fini(&arc_sums.arcstat_evict_l2_skip);
7425 wmsum_fini(&arc_sums.arcstat_hash_collisions);
7426 wmsum_fini(&arc_sums.arcstat_hash_chains);
7427 aggsum_fini(&arc_sums.arcstat_size);
7428 wmsum_fini(&arc_sums.arcstat_compressed_size);
7429 wmsum_fini(&arc_sums.arcstat_uncompressed_size);
7430 wmsum_fini(&arc_sums.arcstat_overhead_size);
7431 wmsum_fini(&arc_sums.arcstat_hdr_size);
7432 wmsum_fini(&arc_sums.arcstat_data_size);
7433 wmsum_fini(&arc_sums.arcstat_metadata_size);
7434 wmsum_fini(&arc_sums.arcstat_dbuf_size);
7435 wmsum_fini(&arc_sums.arcstat_dnode_size);
7436 wmsum_fini(&arc_sums.arcstat_bonus_size);
7437 wmsum_fini(&arc_sums.arcstat_l2_hits);
7438 wmsum_fini(&arc_sums.arcstat_l2_misses);
7439 wmsum_fini(&arc_sums.arcstat_l2_prefetch_asize);
7440 wmsum_fini(&arc_sums.arcstat_l2_mru_asize);
7441 wmsum_fini(&arc_sums.arcstat_l2_mfu_asize);
7442 wmsum_fini(&arc_sums.arcstat_l2_bufc_data_asize);
7443 wmsum_fini(&arc_sums.arcstat_l2_bufc_metadata_asize);
7444 wmsum_fini(&arc_sums.arcstat_l2_feeds);
7445 wmsum_fini(&arc_sums.arcstat_l2_rw_clash);
7446 wmsum_fini(&arc_sums.arcstat_l2_read_bytes);
7447 wmsum_fini(&arc_sums.arcstat_l2_write_bytes);
7448 wmsum_fini(&arc_sums.arcstat_l2_writes_sent);
7449 wmsum_fini(&arc_sums.arcstat_l2_writes_done);
7450 wmsum_fini(&arc_sums.arcstat_l2_writes_error);
7451 wmsum_fini(&arc_sums.arcstat_l2_writes_lock_retry);
7452 wmsum_fini(&arc_sums.arcstat_l2_evict_lock_retry);
7453 wmsum_fini(&arc_sums.arcstat_l2_evict_reading);
7454 wmsum_fini(&arc_sums.arcstat_l2_evict_l1cached);
7455 wmsum_fini(&arc_sums.arcstat_l2_free_on_write);
7456 wmsum_fini(&arc_sums.arcstat_l2_abort_lowmem);
7457 wmsum_fini(&arc_sums.arcstat_l2_cksum_bad);
7458 wmsum_fini(&arc_sums.arcstat_l2_io_error);
7459 wmsum_fini(&arc_sums.arcstat_l2_lsize);
7460 wmsum_fini(&arc_sums.arcstat_l2_psize);
7461 aggsum_fini(&arc_sums.arcstat_l2_hdr_size);
7462 wmsum_fini(&arc_sums.arcstat_l2_log_blk_writes);
7463 wmsum_fini(&arc_sums.arcstat_l2_log_blk_asize);
7464 wmsum_fini(&arc_sums.arcstat_l2_log_blk_count);
7465 wmsum_fini(&arc_sums.arcstat_l2_rebuild_success);
7466 wmsum_fini(&arc_sums.arcstat_l2_rebuild_abort_unsupported);
7467 wmsum_fini(&arc_sums.arcstat_l2_rebuild_abort_io_errors);
7468 wmsum_fini(&arc_sums.arcstat_l2_rebuild_abort_dh_errors);
7469 wmsum_fini(&arc_sums.arcstat_l2_rebuild_abort_cksum_lb_errors);
7470 wmsum_fini(&arc_sums.arcstat_l2_rebuild_abort_lowmem);
7471 wmsum_fini(&arc_sums.arcstat_l2_rebuild_size);
7472 wmsum_fini(&arc_sums.arcstat_l2_rebuild_asize);
7473 wmsum_fini(&arc_sums.arcstat_l2_rebuild_bufs);
7474 wmsum_fini(&arc_sums.arcstat_l2_rebuild_bufs_precached);
7475 wmsum_fini(&arc_sums.arcstat_l2_rebuild_log_blks);
7476 wmsum_fini(&arc_sums.arcstat_memory_throttle_count);
7477 wmsum_fini(&arc_sums.arcstat_memory_direct_count);
7478 wmsum_fini(&arc_sums.arcstat_memory_indirect_count);
7479 wmsum_fini(&arc_sums.arcstat_prune);
7480 wmsum_fini(&arc_sums.arcstat_meta_used);
7481 wmsum_fini(&arc_sums.arcstat_async_upgrade_sync);
7482 wmsum_fini(&arc_sums.arcstat_predictive_prefetch);
7483 wmsum_fini(&arc_sums.arcstat_demand_hit_predictive_prefetch);
7484 wmsum_fini(&arc_sums.arcstat_demand_iohit_predictive_prefetch);
7485 wmsum_fini(&arc_sums.arcstat_prescient_prefetch);
7486 wmsum_fini(&arc_sums.arcstat_demand_hit_prescient_prefetch);
7487 wmsum_fini(&arc_sums.arcstat_demand_iohit_prescient_prefetch);
7488 wmsum_fini(&arc_sums.arcstat_raw_size);
7489 wmsum_fini(&arc_sums.arcstat_cached_only_in_progress);
7490 wmsum_fini(&arc_sums.arcstat_abd_chunk_waste_size);
7494 arc_target_bytes(void)
7500 arc_set_limits(uint64_t allmem)
7502 /* Set min cache to 1/32 of all memory, or 32MB, whichever is more. */
7503 arc_c_min = MAX(allmem / 32, 2ULL << SPA_MAXBLOCKSHIFT);
7505 /* How to set default max varies by platform. */
7506 arc_c_max = arc_default_max(arc_c_min, allmem);
7511 uint64_t percent, allmem = arc_all_memory();
7512 mutex_init(&arc_evict_lock, NULL, MUTEX_DEFAULT, NULL);
7513 list_create(&arc_evict_waiters, sizeof (arc_evict_waiter_t),
7514 offsetof(arc_evict_waiter_t, aew_node));
7516 arc_min_prefetch_ms = 1000;
7517 arc_min_prescient_prefetch_ms = 6000;
7519 #if defined(_KERNEL)
7523 arc_set_limits(allmem);
7527 * If zfs_arc_max is non-zero at init, meaning it was set in the kernel
7528 * environment before the module was loaded, don't block setting the
7529 * maximum because it is less than arc_c_min, instead, reset arc_c_min
7531 * zfs_arc_min will be handled by arc_tuning_update().
7533 if (zfs_arc_max != 0 && zfs_arc_max >= MIN_ARC_MAX &&
7534 zfs_arc_max < allmem) {
7535 arc_c_max = zfs_arc_max;
7536 if (arc_c_min >= arc_c_max) {
7537 arc_c_min = MAX(zfs_arc_max / 2,
7538 2ULL << SPA_MAXBLOCKSHIFT);
7543 * In userland, there's only the memory pressure that we artificially
7544 * create (see arc_available_memory()). Don't let arc_c get too
7545 * small, because it can cause transactions to be larger than
7546 * arc_c, causing arc_tempreserve_space() to fail.
7548 arc_c_min = MAX(arc_c_max / 2, 2ULL << SPA_MAXBLOCKSHIFT);
7553 * 32-bit fixed point fractions of metadata from total ARC size,
7554 * MRU data from all data and MRU metadata from all metadata.
7556 arc_meta = (1ULL << 32) / 4; /* Metadata is 25% of arc_c. */
7557 arc_pd = (1ULL << 32) / 2; /* Data MRU is 50% of data. */
7558 arc_pm = (1ULL << 32) / 2; /* Metadata MRU is 50% of metadata. */
7560 percent = MIN(zfs_arc_dnode_limit_percent, 100);
7561 arc_dnode_limit = arc_c_max * percent / 100;
7563 /* Apply user specified tunings */
7564 arc_tuning_update(B_TRUE);
7566 /* if kmem_flags are set, lets try to use less memory */
7567 if (kmem_debugging())
7569 if (arc_c < arc_c_min)
7572 arc_register_hotplug();
7578 list_create(&arc_prune_list, sizeof (arc_prune_t),
7579 offsetof(arc_prune_t, p_node));
7580 mutex_init(&arc_prune_mtx, NULL, MUTEX_DEFAULT, NULL);
7582 arc_prune_taskq = taskq_create("arc_prune", zfs_arc_prune_task_threads,
7583 defclsyspri, 100, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
7585 arc_ksp = kstat_create("zfs", 0, "arcstats", "misc", KSTAT_TYPE_NAMED,
7586 sizeof (arc_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL);
7588 if (arc_ksp != NULL) {
7589 arc_ksp->ks_data = &arc_stats;
7590 arc_ksp->ks_update = arc_kstat_update;
7591 kstat_install(arc_ksp);
7594 arc_state_evict_markers =
7595 arc_state_alloc_markers(arc_state_evict_marker_count);
7596 arc_evict_zthr = zthr_create_timer("arc_evict",
7597 arc_evict_cb_check, arc_evict_cb, NULL, SEC2NSEC(1), defclsyspri);
7598 arc_reap_zthr = zthr_create_timer("arc_reap",
7599 arc_reap_cb_check, arc_reap_cb, NULL, SEC2NSEC(1), minclsyspri);
7604 * Calculate maximum amount of dirty data per pool.
7606 * If it has been set by a module parameter, take that.
7607 * Otherwise, use a percentage of physical memory defined by
7608 * zfs_dirty_data_max_percent (default 10%) with a cap at
7609 * zfs_dirty_data_max_max (default 4G or 25% of physical memory).
7612 if (zfs_dirty_data_max_max == 0)
7613 zfs_dirty_data_max_max = MIN(4ULL * 1024 * 1024 * 1024,
7614 allmem * zfs_dirty_data_max_max_percent / 100);
7616 if (zfs_dirty_data_max_max == 0)
7617 zfs_dirty_data_max_max = MIN(1ULL * 1024 * 1024 * 1024,
7618 allmem * zfs_dirty_data_max_max_percent / 100);
7621 if (zfs_dirty_data_max == 0) {
7622 zfs_dirty_data_max = allmem *
7623 zfs_dirty_data_max_percent / 100;
7624 zfs_dirty_data_max = MIN(zfs_dirty_data_max,
7625 zfs_dirty_data_max_max);
7628 if (zfs_wrlog_data_max == 0) {
7631 * dp_wrlog_total is reduced for each txg at the end of
7632 * spa_sync(). However, dp_dirty_total is reduced every time
7633 * a block is written out. Thus under normal operation,
7634 * dp_wrlog_total could grow 2 times as big as
7635 * zfs_dirty_data_max.
7637 zfs_wrlog_data_max = zfs_dirty_data_max * 2;
7648 #endif /* _KERNEL */
7650 /* Use B_TRUE to ensure *all* buffers are evicted */
7651 arc_flush(NULL, B_TRUE);
7653 if (arc_ksp != NULL) {
7654 kstat_delete(arc_ksp);
7658 taskq_wait(arc_prune_taskq);
7659 taskq_destroy(arc_prune_taskq);
7661 mutex_enter(&arc_prune_mtx);
7662 while ((p = list_remove_head(&arc_prune_list)) != NULL) {
7663 zfs_refcount_remove(&p->p_refcnt, &arc_prune_list);
7664 zfs_refcount_destroy(&p->p_refcnt);
7665 kmem_free(p, sizeof (*p));
7667 mutex_exit(&arc_prune_mtx);
7669 list_destroy(&arc_prune_list);
7670 mutex_destroy(&arc_prune_mtx);
7672 (void) zthr_cancel(arc_evict_zthr);
7673 (void) zthr_cancel(arc_reap_zthr);
7674 arc_state_free_markers(arc_state_evict_markers,
7675 arc_state_evict_marker_count);
7677 mutex_destroy(&arc_evict_lock);
7678 list_destroy(&arc_evict_waiters);
7681 * Free any buffers that were tagged for destruction. This needs
7682 * to occur before arc_state_fini() runs and destroys the aggsum
7683 * values which are updated when freeing scatter ABDs.
7685 l2arc_do_free_on_write();
7688 * buf_fini() must proceed arc_state_fini() because buf_fin() may
7689 * trigger the release of kmem magazines, which can callback to
7690 * arc_space_return() which accesses aggsums freed in act_state_fini().
7695 arc_unregister_hotplug();
7698 * We destroy the zthrs after all the ARC state has been
7699 * torn down to avoid the case of them receiving any
7700 * wakeup() signals after they are destroyed.
7702 zthr_destroy(arc_evict_zthr);
7703 zthr_destroy(arc_reap_zthr);
7705 ASSERT0(arc_loaned_bytes);
7711 * The level 2 ARC (L2ARC) is a cache layer in-between main memory and disk.
7712 * It uses dedicated storage devices to hold cached data, which are populated
7713 * using large infrequent writes. The main role of this cache is to boost
7714 * the performance of random read workloads. The intended L2ARC devices
7715 * include short-stroked disks, solid state disks, and other media with
7716 * substantially faster read latency than disk.
7718 * +-----------------------+
7720 * +-----------------------+
7723 * l2arc_feed_thread() arc_read()
7727 * +---------------+ |
7729 * +---------------+ |
7734 * +-------+ +-------+
7736 * | cache | | cache |
7737 * +-------+ +-------+
7738 * +=========+ .-----.
7739 * : L2ARC : |-_____-|
7740 * : devices : | Disks |
7741 * +=========+ `-_____-'
7743 * Read requests are satisfied from the following sources, in order:
7746 * 2) vdev cache of L2ARC devices
7748 * 4) vdev cache of disks
7751 * Some L2ARC device types exhibit extremely slow write performance.
7752 * To accommodate for this there are some significant differences between
7753 * the L2ARC and traditional cache design:
7755 * 1. There is no eviction path from the ARC to the L2ARC. Evictions from
7756 * the ARC behave as usual, freeing buffers and placing headers on ghost
7757 * lists. The ARC does not send buffers to the L2ARC during eviction as
7758 * this would add inflated write latencies for all ARC memory pressure.
7760 * 2. The L2ARC attempts to cache data from the ARC before it is evicted.
7761 * It does this by periodically scanning buffers from the eviction-end of
7762 * the MFU and MRU ARC lists, copying them to the L2ARC devices if they are
7763 * not already there. It scans until a headroom of buffers is satisfied,
7764 * which itself is a buffer for ARC eviction. If a compressible buffer is
7765 * found during scanning and selected for writing to an L2ARC device, we
7766 * temporarily boost scanning headroom during the next scan cycle to make
7767 * sure we adapt to compression effects (which might significantly reduce
7768 * the data volume we write to L2ARC). The thread that does this is
7769 * l2arc_feed_thread(), illustrated below; example sizes are included to
7770 * provide a better sense of ratio than this diagram:
7773 * +---------------------+----------+
7774 * ARC_mfu |:::::#:::::::::::::::|o#o###o###|-->. # already on L2ARC
7775 * +---------------------+----------+ | o L2ARC eligible
7776 * ARC_mru |:#:::::::::::::::::::|#o#ooo####|-->| : ARC buffer
7777 * +---------------------+----------+ |
7778 * 15.9 Gbytes ^ 32 Mbytes |
7780 * l2arc_feed_thread()
7782 * l2arc write hand <--[oooo]--'
7786 * +==============================+
7787 * L2ARC dev |####|#|###|###| |####| ... |
7788 * +==============================+
7791 * 3. If an ARC buffer is copied to the L2ARC but then hit instead of
7792 * evicted, then the L2ARC has cached a buffer much sooner than it probably
7793 * needed to, potentially wasting L2ARC device bandwidth and storage. It is
7794 * safe to say that this is an uncommon case, since buffers at the end of
7795 * the ARC lists have moved there due to inactivity.
7797 * 4. If the ARC evicts faster than the L2ARC can maintain a headroom,
7798 * then the L2ARC simply misses copying some buffers. This serves as a
7799 * pressure valve to prevent heavy read workloads from both stalling the ARC
7800 * with waits and clogging the L2ARC with writes. This also helps prevent
7801 * the potential for the L2ARC to churn if it attempts to cache content too
7802 * quickly, such as during backups of the entire pool.
7804 * 5. After system boot and before the ARC has filled main memory, there are
7805 * no evictions from the ARC and so the tails of the ARC_mfu and ARC_mru
7806 * lists can remain mostly static. Instead of searching from tail of these
7807 * lists as pictured, the l2arc_feed_thread() will search from the list heads
7808 * for eligible buffers, greatly increasing its chance of finding them.
7810 * The L2ARC device write speed is also boosted during this time so that
7811 * the L2ARC warms up faster. Since there have been no ARC evictions yet,
7812 * there are no L2ARC reads, and no fear of degrading read performance
7813 * through increased writes.
7815 * 6. Writes to the L2ARC devices are grouped and sent in-sequence, so that
7816 * the vdev queue can aggregate them into larger and fewer writes. Each
7817 * device is written to in a rotor fashion, sweeping writes through
7818 * available space then repeating.
7820 * 7. The L2ARC does not store dirty content. It never needs to flush
7821 * write buffers back to disk based storage.
7823 * 8. If an ARC buffer is written (and dirtied) which also exists in the
7824 * L2ARC, the now stale L2ARC buffer is immediately dropped.
7826 * The performance of the L2ARC can be tweaked by a number of tunables, which
7827 * may be necessary for different workloads:
7829 * l2arc_write_max max write bytes per interval
7830 * l2arc_write_boost extra write bytes during device warmup
7831 * l2arc_noprefetch skip caching prefetched buffers
7832 * l2arc_headroom number of max device writes to precache
7833 * l2arc_headroom_boost when we find compressed buffers during ARC
7834 * scanning, we multiply headroom by this
7835 * percentage factor for the next scan cycle,
7836 * since more compressed buffers are likely to
7838 * l2arc_feed_secs seconds between L2ARC writing
7840 * Tunables may be removed or added as future performance improvements are
7841 * integrated, and also may become zpool properties.
7843 * There are three key functions that control how the L2ARC warms up:
7845 * l2arc_write_eligible() check if a buffer is eligible to cache
7846 * l2arc_write_size() calculate how much to write
7847 * l2arc_write_interval() calculate sleep delay between writes
7849 * These three functions determine what to write, how much, and how quickly
7852 * L2ARC persistence:
7854 * When writing buffers to L2ARC, we periodically add some metadata to
7855 * make sure we can pick them up after reboot, thus dramatically reducing
7856 * the impact that any downtime has on the performance of storage systems
7857 * with large caches.
7859 * The implementation works fairly simply by integrating the following two
7862 * *) When writing to the L2ARC, we occasionally write a "l2arc log block",
7863 * which is an additional piece of metadata which describes what's been
7864 * written. This allows us to rebuild the arc_buf_hdr_t structures of the
7865 * main ARC buffers. There are 2 linked-lists of log blocks headed by
7866 * dh_start_lbps[2]. We alternate which chain we append to, so they are
7867 * time-wise and offset-wise interleaved, but that is an optimization rather
7868 * than for correctness. The log block also includes a pointer to the
7869 * previous block in its chain.
7871 * *) We reserve SPA_MINBLOCKSIZE of space at the start of each L2ARC device
7872 * for our header bookkeeping purposes. This contains a device header,
7873 * which contains our top-level reference structures. We update it each
7874 * time we write a new log block, so that we're able to locate it in the
7875 * L2ARC device. If this write results in an inconsistent device header
7876 * (e.g. due to power failure), we detect this by verifying the header's
7877 * checksum and simply fail to reconstruct the L2ARC after reboot.
7879 * Implementation diagram:
7881 * +=== L2ARC device (not to scale) ======================================+
7882 * | ___two newest log block pointers__.__________ |
7883 * | / \dh_start_lbps[1] |
7884 * | / \ \dh_start_lbps[0]|
7886 * ||L2 dev|....|lb |bufs |lb |bufs |lb |bufs |lb |bufs |lb |---(empty)---|
7887 * || hdr| ^ /^ /^ / / |
7888 * |+------+ ...--\-------/ \-----/--\------/ / |
7889 * | \--------------/ \--------------/ |
7890 * +======================================================================+
7892 * As can be seen on the diagram, rather than using a simple linked list,
7893 * we use a pair of linked lists with alternating elements. This is a
7894 * performance enhancement due to the fact that we only find out the
7895 * address of the next log block access once the current block has been
7896 * completely read in. Obviously, this hurts performance, because we'd be
7897 * keeping the device's I/O queue at only a 1 operation deep, thus
7898 * incurring a large amount of I/O round-trip latency. Having two lists
7899 * allows us to fetch two log blocks ahead of where we are currently
7900 * rebuilding L2ARC buffers.
7902 * On-device data structures:
7904 * L2ARC device header: l2arc_dev_hdr_phys_t
7905 * L2ARC log block: l2arc_log_blk_phys_t
7907 * L2ARC reconstruction:
7909 * When writing data, we simply write in the standard rotary fashion,
7910 * evicting buffers as we go and simply writing new data over them (writing
7911 * a new log block every now and then). This obviously means that once we
7912 * loop around the end of the device, we will start cutting into an already
7913 * committed log block (and its referenced data buffers), like so:
7915 * current write head__ __old tail
7918 * <--|bufs |lb |bufs |lb | |bufs |lb |bufs |lb |-->
7919 * ^ ^^^^^^^^^___________________________________
7921 * <<nextwrite>> may overwrite this blk and/or its bufs --'
7923 * When importing the pool, we detect this situation and use it to stop
7924 * our scanning process (see l2arc_rebuild).
7926 * There is one significant caveat to consider when rebuilding ARC contents
7927 * from an L2ARC device: what about invalidated buffers? Given the above
7928 * construction, we cannot update blocks which we've already written to amend
7929 * them to remove buffers which were invalidated. Thus, during reconstruction,
7930 * we might be populating the cache with buffers for data that's not on the
7931 * main pool anymore, or may have been overwritten!
7933 * As it turns out, this isn't a problem. Every arc_read request includes
7934 * both the DVA and, crucially, the birth TXG of the BP the caller is
7935 * looking for. So even if the cache were populated by completely rotten
7936 * blocks for data that had been long deleted and/or overwritten, we'll
7937 * never actually return bad data from the cache, since the DVA with the
7938 * birth TXG uniquely identify a block in space and time - once created,
7939 * a block is immutable on disk. The worst thing we have done is wasted
7940 * some time and memory at l2arc rebuild to reconstruct outdated ARC
7941 * entries that will get dropped from the l2arc as it is being updated
7944 * L2ARC buffers that have been evicted by l2arc_evict() ahead of the write
7945 * hand are not restored. This is done by saving the offset (in bytes)
7946 * l2arc_evict() has evicted to in the L2ARC device header and taking it
7947 * into account when restoring buffers.
7951 l2arc_write_eligible(uint64_t spa_guid, arc_buf_hdr_t *hdr)
7954 * A buffer is *not* eligible for the L2ARC if it:
7955 * 1. belongs to a different spa.
7956 * 2. is already cached on the L2ARC.
7957 * 3. has an I/O in progress (it may be an incomplete read).
7958 * 4. is flagged not eligible (zfs property).
7960 if (hdr->b_spa != spa_guid || HDR_HAS_L2HDR(hdr) ||
7961 HDR_IO_IN_PROGRESS(hdr) || !HDR_L2CACHE(hdr))
7968 l2arc_write_size(l2arc_dev_t *dev)
7973 * Make sure our globals have meaningful values in case the user
7976 size = l2arc_write_max;
7978 cmn_err(CE_NOTE, "Bad value for l2arc_write_max, value must "
7979 "be greater than zero, resetting it to the default (%d)",
7981 size = l2arc_write_max = L2ARC_WRITE_SIZE;
7984 if (arc_warm == B_FALSE)
7985 size += l2arc_write_boost;
7987 /* We need to add in the worst case scenario of log block overhead. */
7988 size += l2arc_log_blk_overhead(size, dev);
7989 if (dev->l2ad_vdev->vdev_has_trim && l2arc_trim_ahead > 0) {
7991 * Trim ahead of the write size 64MB or (l2arc_trim_ahead/100)
7992 * times the writesize, whichever is greater.
7994 size += MAX(64 * 1024 * 1024,
7995 (size * l2arc_trim_ahead) / 100);
7999 * Make sure the write size does not exceed the size of the cache
8000 * device. This is important in l2arc_evict(), otherwise infinite
8001 * iteration can occur.
8003 if (size > dev->l2ad_end - dev->l2ad_start) {
8004 cmn_err(CE_NOTE, "l2arc_write_max or l2arc_write_boost "
8005 "plus the overhead of log blocks (persistent L2ARC, "
8006 "%llu bytes) exceeds the size of the cache device "
8007 "(guid %llu), resetting them to the default (%d)",
8008 (u_longlong_t)l2arc_log_blk_overhead(size, dev),
8009 (u_longlong_t)dev->l2ad_vdev->vdev_guid, L2ARC_WRITE_SIZE);
8011 size = l2arc_write_max = l2arc_write_boost = L2ARC_WRITE_SIZE;
8013 if (l2arc_trim_ahead > 1) {
8014 cmn_err(CE_NOTE, "l2arc_trim_ahead set to 1");
8015 l2arc_trim_ahead = 1;
8018 if (arc_warm == B_FALSE)
8019 size += l2arc_write_boost;
8021 size += l2arc_log_blk_overhead(size, dev);
8022 if (dev->l2ad_vdev->vdev_has_trim && l2arc_trim_ahead > 0) {
8023 size += MAX(64 * 1024 * 1024,
8024 (size * l2arc_trim_ahead) / 100);
8033 l2arc_write_interval(clock_t began, uint64_t wanted, uint64_t wrote)
8035 clock_t interval, next, now;
8038 * If the ARC lists are busy, increase our write rate; if the
8039 * lists are stale, idle back. This is achieved by checking
8040 * how much we previously wrote - if it was more than half of
8041 * what we wanted, schedule the next write much sooner.
8043 if (l2arc_feed_again && wrote > (wanted / 2))
8044 interval = (hz * l2arc_feed_min_ms) / 1000;
8046 interval = hz * l2arc_feed_secs;
8048 now = ddi_get_lbolt();
8049 next = MAX(now, MIN(now + interval, began + interval));
8055 * Cycle through L2ARC devices. This is how L2ARC load balances.
8056 * If a device is returned, this also returns holding the spa config lock.
8058 static l2arc_dev_t *
8059 l2arc_dev_get_next(void)
8061 l2arc_dev_t *first, *next = NULL;
8064 * Lock out the removal of spas (spa_namespace_lock), then removal
8065 * of cache devices (l2arc_dev_mtx). Once a device has been selected,
8066 * both locks will be dropped and a spa config lock held instead.
8068 mutex_enter(&spa_namespace_lock);
8069 mutex_enter(&l2arc_dev_mtx);
8071 /* if there are no vdevs, there is nothing to do */
8072 if (l2arc_ndev == 0)
8076 next = l2arc_dev_last;
8078 /* loop around the list looking for a non-faulted vdev */
8080 next = list_head(l2arc_dev_list);
8082 next = list_next(l2arc_dev_list, next);
8084 next = list_head(l2arc_dev_list);
8087 /* if we have come back to the start, bail out */
8090 else if (next == first)
8093 ASSERT3P(next, !=, NULL);
8094 } while (vdev_is_dead(next->l2ad_vdev) || next->l2ad_rebuild ||
8095 next->l2ad_trim_all);
8097 /* if we were unable to find any usable vdevs, return NULL */
8098 if (vdev_is_dead(next->l2ad_vdev) || next->l2ad_rebuild ||
8099 next->l2ad_trim_all)
8102 l2arc_dev_last = next;
8105 mutex_exit(&l2arc_dev_mtx);
8108 * Grab the config lock to prevent the 'next' device from being
8109 * removed while we are writing to it.
8112 spa_config_enter(next->l2ad_spa, SCL_L2ARC, next, RW_READER);
8113 mutex_exit(&spa_namespace_lock);
8119 * Free buffers that were tagged for destruction.
8122 l2arc_do_free_on_write(void)
8124 l2arc_data_free_t *df;
8126 mutex_enter(&l2arc_free_on_write_mtx);
8127 while ((df = list_remove_head(l2arc_free_on_write)) != NULL) {
8128 ASSERT3P(df->l2df_abd, !=, NULL);
8129 abd_free(df->l2df_abd);
8130 kmem_free(df, sizeof (l2arc_data_free_t));
8132 mutex_exit(&l2arc_free_on_write_mtx);
8136 * A write to a cache device has completed. Update all headers to allow
8137 * reads from these buffers to begin.
8140 l2arc_write_done(zio_t *zio)
8142 l2arc_write_callback_t *cb;
8143 l2arc_lb_abd_buf_t *abd_buf;
8144 l2arc_lb_ptr_buf_t *lb_ptr_buf;
8146 l2arc_dev_hdr_phys_t *l2dhdr;
8148 arc_buf_hdr_t *head, *hdr, *hdr_prev;
8149 kmutex_t *hash_lock;
8150 int64_t bytes_dropped = 0;
8152 cb = zio->io_private;
8153 ASSERT3P(cb, !=, NULL);
8154 dev = cb->l2wcb_dev;
8155 l2dhdr = dev->l2ad_dev_hdr;
8156 ASSERT3P(dev, !=, NULL);
8157 head = cb->l2wcb_head;
8158 ASSERT3P(head, !=, NULL);
8159 buflist = &dev->l2ad_buflist;
8160 ASSERT3P(buflist, !=, NULL);
8161 DTRACE_PROBE2(l2arc__iodone, zio_t *, zio,
8162 l2arc_write_callback_t *, cb);
8165 * All writes completed, or an error was hit.
8168 mutex_enter(&dev->l2ad_mtx);
8169 for (hdr = list_prev(buflist, head); hdr; hdr = hdr_prev) {
8170 hdr_prev = list_prev(buflist, hdr);
8172 hash_lock = HDR_LOCK(hdr);
8175 * We cannot use mutex_enter or else we can deadlock
8176 * with l2arc_write_buffers (due to swapping the order
8177 * the hash lock and l2ad_mtx are taken).
8179 if (!mutex_tryenter(hash_lock)) {
8181 * Missed the hash lock. We must retry so we
8182 * don't leave the ARC_FLAG_L2_WRITING bit set.
8184 ARCSTAT_BUMP(arcstat_l2_writes_lock_retry);
8187 * We don't want to rescan the headers we've
8188 * already marked as having been written out, so
8189 * we reinsert the head node so we can pick up
8190 * where we left off.
8192 list_remove(buflist, head);
8193 list_insert_after(buflist, hdr, head);
8195 mutex_exit(&dev->l2ad_mtx);
8198 * We wait for the hash lock to become available
8199 * to try and prevent busy waiting, and increase
8200 * the chance we'll be able to acquire the lock
8201 * the next time around.
8203 mutex_enter(hash_lock);
8204 mutex_exit(hash_lock);
8209 * We could not have been moved into the arc_l2c_only
8210 * state while in-flight due to our ARC_FLAG_L2_WRITING
8211 * bit being set. Let's just ensure that's being enforced.
8213 ASSERT(HDR_HAS_L1HDR(hdr));
8216 * Skipped - drop L2ARC entry and mark the header as no
8217 * longer L2 eligibile.
8219 if (zio->io_error != 0) {
8221 * Error - drop L2ARC entry.
8223 list_remove(buflist, hdr);
8224 arc_hdr_clear_flags(hdr, ARC_FLAG_HAS_L2HDR);
8226 uint64_t psize = HDR_GET_PSIZE(hdr);
8227 l2arc_hdr_arcstats_decrement(hdr);
8230 vdev_psize_to_asize(dev->l2ad_vdev, psize);
8231 (void) zfs_refcount_remove_many(&dev->l2ad_alloc,
8232 arc_hdr_size(hdr), hdr);
8236 * Allow ARC to begin reads and ghost list evictions to
8239 arc_hdr_clear_flags(hdr, ARC_FLAG_L2_WRITING);
8241 mutex_exit(hash_lock);
8245 * Free the allocated abd buffers for writing the log blocks.
8246 * If the zio failed reclaim the allocated space and remove the
8247 * pointers to these log blocks from the log block pointer list
8248 * of the L2ARC device.
8250 while ((abd_buf = list_remove_tail(&cb->l2wcb_abd_list)) != NULL) {
8251 abd_free(abd_buf->abd);
8252 zio_buf_free(abd_buf, sizeof (*abd_buf));
8253 if (zio->io_error != 0) {
8254 lb_ptr_buf = list_remove_head(&dev->l2ad_lbptr_list);
8256 * L2BLK_GET_PSIZE returns aligned size for log
8260 L2BLK_GET_PSIZE((lb_ptr_buf->lb_ptr)->lbp_prop);
8261 bytes_dropped += asize;
8262 ARCSTAT_INCR(arcstat_l2_log_blk_asize, -asize);
8263 ARCSTAT_BUMPDOWN(arcstat_l2_log_blk_count);
8264 zfs_refcount_remove_many(&dev->l2ad_lb_asize, asize,
8266 zfs_refcount_remove(&dev->l2ad_lb_count, lb_ptr_buf);
8267 kmem_free(lb_ptr_buf->lb_ptr,
8268 sizeof (l2arc_log_blkptr_t));
8269 kmem_free(lb_ptr_buf, sizeof (l2arc_lb_ptr_buf_t));
8272 list_destroy(&cb->l2wcb_abd_list);
8274 if (zio->io_error != 0) {
8275 ARCSTAT_BUMP(arcstat_l2_writes_error);
8278 * Restore the lbps array in the header to its previous state.
8279 * If the list of log block pointers is empty, zero out the
8280 * log block pointers in the device header.
8282 lb_ptr_buf = list_head(&dev->l2ad_lbptr_list);
8283 for (int i = 0; i < 2; i++) {
8284 if (lb_ptr_buf == NULL) {
8286 * If the list is empty zero out the device
8287 * header. Otherwise zero out the second log
8288 * block pointer in the header.
8292 dev->l2ad_dev_hdr_asize);
8294 memset(&l2dhdr->dh_start_lbps[i], 0,
8295 sizeof (l2arc_log_blkptr_t));
8299 memcpy(&l2dhdr->dh_start_lbps[i], lb_ptr_buf->lb_ptr,
8300 sizeof (l2arc_log_blkptr_t));
8301 lb_ptr_buf = list_next(&dev->l2ad_lbptr_list,
8306 ARCSTAT_BUMP(arcstat_l2_writes_done);
8307 list_remove(buflist, head);
8308 ASSERT(!HDR_HAS_L1HDR(head));
8309 kmem_cache_free(hdr_l2only_cache, head);
8310 mutex_exit(&dev->l2ad_mtx);
8312 ASSERT(dev->l2ad_vdev != NULL);
8313 vdev_space_update(dev->l2ad_vdev, -bytes_dropped, 0, 0);
8315 l2arc_do_free_on_write();
8317 kmem_free(cb, sizeof (l2arc_write_callback_t));
8321 l2arc_untransform(zio_t *zio, l2arc_read_callback_t *cb)
8324 spa_t *spa = zio->io_spa;
8325 arc_buf_hdr_t *hdr = cb->l2rcb_hdr;
8326 blkptr_t *bp = zio->io_bp;
8327 uint8_t salt[ZIO_DATA_SALT_LEN];
8328 uint8_t iv[ZIO_DATA_IV_LEN];
8329 uint8_t mac[ZIO_DATA_MAC_LEN];
8330 boolean_t no_crypt = B_FALSE;
8333 * ZIL data is never be written to the L2ARC, so we don't need
8334 * special handling for its unique MAC storage.
8336 ASSERT3U(BP_GET_TYPE(bp), !=, DMU_OT_INTENT_LOG);
8337 ASSERT(MUTEX_HELD(HDR_LOCK(hdr)));
8338 ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
8341 * If the data was encrypted, decrypt it now. Note that
8342 * we must check the bp here and not the hdr, since the
8343 * hdr does not have its encryption parameters updated
8344 * until arc_read_done().
8346 if (BP_IS_ENCRYPTED(bp)) {
8347 abd_t *eabd = arc_get_data_abd(hdr, arc_hdr_size(hdr), hdr,
8348 ARC_HDR_USE_RESERVE);
8350 zio_crypt_decode_params_bp(bp, salt, iv);
8351 zio_crypt_decode_mac_bp(bp, mac);
8353 ret = spa_do_crypt_abd(B_FALSE, spa, &cb->l2rcb_zb,
8354 BP_GET_TYPE(bp), BP_GET_DEDUP(bp), BP_SHOULD_BYTESWAP(bp),
8355 salt, iv, mac, HDR_GET_PSIZE(hdr), eabd,
8356 hdr->b_l1hdr.b_pabd, &no_crypt);
8358 arc_free_data_abd(hdr, eabd, arc_hdr_size(hdr), hdr);
8363 * If we actually performed decryption, replace b_pabd
8364 * with the decrypted data. Otherwise we can just throw
8365 * our decryption buffer away.
8368 arc_free_data_abd(hdr, hdr->b_l1hdr.b_pabd,
8369 arc_hdr_size(hdr), hdr);
8370 hdr->b_l1hdr.b_pabd = eabd;
8373 arc_free_data_abd(hdr, eabd, arc_hdr_size(hdr), hdr);
8378 * If the L2ARC block was compressed, but ARC compression
8379 * is disabled we decompress the data into a new buffer and
8380 * replace the existing data.
8382 if (HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF &&
8383 !HDR_COMPRESSION_ENABLED(hdr)) {
8384 abd_t *cabd = arc_get_data_abd(hdr, arc_hdr_size(hdr), hdr,
8385 ARC_HDR_USE_RESERVE);
8386 void *tmp = abd_borrow_buf(cabd, arc_hdr_size(hdr));
8388 ret = zio_decompress_data(HDR_GET_COMPRESS(hdr),
8389 hdr->b_l1hdr.b_pabd, tmp, HDR_GET_PSIZE(hdr),
8390 HDR_GET_LSIZE(hdr), &hdr->b_complevel);
8392 abd_return_buf_copy(cabd, tmp, arc_hdr_size(hdr));
8393 arc_free_data_abd(hdr, cabd, arc_hdr_size(hdr), hdr);
8397 abd_return_buf_copy(cabd, tmp, arc_hdr_size(hdr));
8398 arc_free_data_abd(hdr, hdr->b_l1hdr.b_pabd,
8399 arc_hdr_size(hdr), hdr);
8400 hdr->b_l1hdr.b_pabd = cabd;
8402 zio->io_size = HDR_GET_LSIZE(hdr);
8413 * A read to a cache device completed. Validate buffer contents before
8414 * handing over to the regular ARC routines.
8417 l2arc_read_done(zio_t *zio)
8420 l2arc_read_callback_t *cb = zio->io_private;
8422 kmutex_t *hash_lock;
8423 boolean_t valid_cksum;
8424 boolean_t using_rdata = (BP_IS_ENCRYPTED(&cb->l2rcb_bp) &&
8425 (cb->l2rcb_flags & ZIO_FLAG_RAW_ENCRYPT));
8427 ASSERT3P(zio->io_vd, !=, NULL);
8428 ASSERT(zio->io_flags & ZIO_FLAG_DONT_PROPAGATE);
8430 spa_config_exit(zio->io_spa, SCL_L2ARC, zio->io_vd);
8432 ASSERT3P(cb, !=, NULL);
8433 hdr = cb->l2rcb_hdr;
8434 ASSERT3P(hdr, !=, NULL);
8436 hash_lock = HDR_LOCK(hdr);
8437 mutex_enter(hash_lock);
8438 ASSERT3P(hash_lock, ==, HDR_LOCK(hdr));
8441 * If the data was read into a temporary buffer,
8442 * move it and free the buffer.
8444 if (cb->l2rcb_abd != NULL) {
8445 ASSERT3U(arc_hdr_size(hdr), <, zio->io_size);
8446 if (zio->io_error == 0) {
8448 abd_copy(hdr->b_crypt_hdr.b_rabd,
8449 cb->l2rcb_abd, arc_hdr_size(hdr));
8451 abd_copy(hdr->b_l1hdr.b_pabd,
8452 cb->l2rcb_abd, arc_hdr_size(hdr));
8457 * The following must be done regardless of whether
8458 * there was an error:
8459 * - free the temporary buffer
8460 * - point zio to the real ARC buffer
8461 * - set zio size accordingly
8462 * These are required because zio is either re-used for
8463 * an I/O of the block in the case of the error
8464 * or the zio is passed to arc_read_done() and it
8467 abd_free(cb->l2rcb_abd);
8468 zio->io_size = zio->io_orig_size = arc_hdr_size(hdr);
8471 ASSERT(HDR_HAS_RABD(hdr));
8472 zio->io_abd = zio->io_orig_abd =
8473 hdr->b_crypt_hdr.b_rabd;
8475 ASSERT3P(hdr->b_l1hdr.b_pabd, !=, NULL);
8476 zio->io_abd = zio->io_orig_abd = hdr->b_l1hdr.b_pabd;
8480 ASSERT3P(zio->io_abd, !=, NULL);
8483 * Check this survived the L2ARC journey.
8485 ASSERT(zio->io_abd == hdr->b_l1hdr.b_pabd ||
8486 (HDR_HAS_RABD(hdr) && zio->io_abd == hdr->b_crypt_hdr.b_rabd));
8487 zio->io_bp_copy = cb->l2rcb_bp; /* XXX fix in L2ARC 2.0 */
8488 zio->io_bp = &zio->io_bp_copy; /* XXX fix in L2ARC 2.0 */
8489 zio->io_prop.zp_complevel = hdr->b_complevel;
8491 valid_cksum = arc_cksum_is_equal(hdr, zio);
8494 * b_rabd will always match the data as it exists on disk if it is
8495 * being used. Therefore if we are reading into b_rabd we do not
8496 * attempt to untransform the data.
8498 if (valid_cksum && !using_rdata)
8499 tfm_error = l2arc_untransform(zio, cb);
8501 if (valid_cksum && tfm_error == 0 && zio->io_error == 0 &&
8502 !HDR_L2_EVICTED(hdr)) {
8503 mutex_exit(hash_lock);
8504 zio->io_private = hdr;
8508 * Buffer didn't survive caching. Increment stats and
8509 * reissue to the original storage device.
8511 if (zio->io_error != 0) {
8512 ARCSTAT_BUMP(arcstat_l2_io_error);
8514 zio->io_error = SET_ERROR(EIO);
8516 if (!valid_cksum || tfm_error != 0)
8517 ARCSTAT_BUMP(arcstat_l2_cksum_bad);
8520 * If there's no waiter, issue an async i/o to the primary
8521 * storage now. If there *is* a waiter, the caller must
8522 * issue the i/o in a context where it's OK to block.
8524 if (zio->io_waiter == NULL) {
8525 zio_t *pio = zio_unique_parent(zio);
8526 void *abd = (using_rdata) ?
8527 hdr->b_crypt_hdr.b_rabd : hdr->b_l1hdr.b_pabd;
8529 ASSERT(!pio || pio->io_child_type == ZIO_CHILD_LOGICAL);
8531 zio = zio_read(pio, zio->io_spa, zio->io_bp,
8532 abd, zio->io_size, arc_read_done,
8533 hdr, zio->io_priority, cb->l2rcb_flags,
8537 * Original ZIO will be freed, so we need to update
8538 * ARC header with the new ZIO pointer to be used
8539 * by zio_change_priority() in arc_read().
8541 for (struct arc_callback *acb = hdr->b_l1hdr.b_acb;
8542 acb != NULL; acb = acb->acb_next)
8543 acb->acb_zio_head = zio;
8545 mutex_exit(hash_lock);
8548 mutex_exit(hash_lock);
8552 kmem_free(cb, sizeof (l2arc_read_callback_t));
8556 * This is the list priority from which the L2ARC will search for pages to
8557 * cache. This is used within loops (0..3) to cycle through lists in the
8558 * desired order. This order can have a significant effect on cache
8561 * Currently the metadata lists are hit first, MFU then MRU, followed by
8562 * the data lists. This function returns a locked list, and also returns
8565 static multilist_sublist_t *
8566 l2arc_sublist_lock(int list_num)
8568 multilist_t *ml = NULL;
8571 ASSERT(list_num >= 0 && list_num < L2ARC_FEED_TYPES);
8575 ml = &arc_mfu->arcs_list[ARC_BUFC_METADATA];
8578 ml = &arc_mru->arcs_list[ARC_BUFC_METADATA];
8581 ml = &arc_mfu->arcs_list[ARC_BUFC_DATA];
8584 ml = &arc_mru->arcs_list[ARC_BUFC_DATA];
8591 * Return a randomly-selected sublist. This is acceptable
8592 * because the caller feeds only a little bit of data for each
8593 * call (8MB). Subsequent calls will result in different
8594 * sublists being selected.
8596 idx = multilist_get_random_index(ml);
8597 return (multilist_sublist_lock(ml, idx));
8601 * Calculates the maximum overhead of L2ARC metadata log blocks for a given
8602 * L2ARC write size. l2arc_evict and l2arc_write_size need to include this
8603 * overhead in processing to make sure there is enough headroom available
8604 * when writing buffers.
8606 static inline uint64_t
8607 l2arc_log_blk_overhead(uint64_t write_sz, l2arc_dev_t *dev)
8609 if (dev->l2ad_log_entries == 0) {
8612 uint64_t log_entries = write_sz >> SPA_MINBLOCKSHIFT;
8614 uint64_t log_blocks = (log_entries +
8615 dev->l2ad_log_entries - 1) /
8616 dev->l2ad_log_entries;
8618 return (vdev_psize_to_asize(dev->l2ad_vdev,
8619 sizeof (l2arc_log_blk_phys_t)) * log_blocks);
8624 * Evict buffers from the device write hand to the distance specified in
8625 * bytes. This distance may span populated buffers, it may span nothing.
8626 * This is clearing a region on the L2ARC device ready for writing.
8627 * If the 'all' boolean is set, every buffer is evicted.
8630 l2arc_evict(l2arc_dev_t *dev, uint64_t distance, boolean_t all)
8633 arc_buf_hdr_t *hdr, *hdr_prev;
8634 kmutex_t *hash_lock;
8636 l2arc_lb_ptr_buf_t *lb_ptr_buf, *lb_ptr_buf_prev;
8637 vdev_t *vd = dev->l2ad_vdev;
8640 buflist = &dev->l2ad_buflist;
8644 if (dev->l2ad_hand + distance > dev->l2ad_end) {
8646 * When there is no space to accommodate upcoming writes,
8647 * evict to the end. Then bump the write and evict hands
8648 * to the start and iterate. This iteration does not
8649 * happen indefinitely as we make sure in
8650 * l2arc_write_size() that when the write hand is reset,
8651 * the write size does not exceed the end of the device.
8654 taddr = dev->l2ad_end;
8656 taddr = dev->l2ad_hand + distance;
8658 DTRACE_PROBE4(l2arc__evict, l2arc_dev_t *, dev, list_t *, buflist,
8659 uint64_t, taddr, boolean_t, all);
8663 * This check has to be placed after deciding whether to
8666 if (dev->l2ad_first) {
8668 * This is the first sweep through the device. There is
8669 * nothing to evict. We have already trimmmed the
8675 * Trim the space to be evicted.
8677 if (vd->vdev_has_trim && dev->l2ad_evict < taddr &&
8678 l2arc_trim_ahead > 0) {
8680 * We have to drop the spa_config lock because
8681 * vdev_trim_range() will acquire it.
8682 * l2ad_evict already accounts for the label
8683 * size. To prevent vdev_trim_ranges() from
8684 * adding it again, we subtract it from
8687 spa_config_exit(dev->l2ad_spa, SCL_L2ARC, dev);
8688 vdev_trim_simple(vd,
8689 dev->l2ad_evict - VDEV_LABEL_START_SIZE,
8690 taddr - dev->l2ad_evict);
8691 spa_config_enter(dev->l2ad_spa, SCL_L2ARC, dev,
8696 * When rebuilding L2ARC we retrieve the evict hand
8697 * from the header of the device. Of note, l2arc_evict()
8698 * does not actually delete buffers from the cache
8699 * device, but trimming may do so depending on the
8700 * hardware implementation. Thus keeping track of the
8701 * evict hand is useful.
8703 dev->l2ad_evict = MAX(dev->l2ad_evict, taddr);
8708 mutex_enter(&dev->l2ad_mtx);
8710 * We have to account for evicted log blocks. Run vdev_space_update()
8711 * on log blocks whose offset (in bytes) is before the evicted offset
8712 * (in bytes) by searching in the list of pointers to log blocks
8713 * present in the L2ARC device.
8715 for (lb_ptr_buf = list_tail(&dev->l2ad_lbptr_list); lb_ptr_buf;
8716 lb_ptr_buf = lb_ptr_buf_prev) {
8718 lb_ptr_buf_prev = list_prev(&dev->l2ad_lbptr_list, lb_ptr_buf);
8720 /* L2BLK_GET_PSIZE returns aligned size for log blocks */
8721 uint64_t asize = L2BLK_GET_PSIZE(
8722 (lb_ptr_buf->lb_ptr)->lbp_prop);
8725 * We don't worry about log blocks left behind (ie
8726 * lbp_payload_start < l2ad_hand) because l2arc_write_buffers()
8727 * will never write more than l2arc_evict() evicts.
8729 if (!all && l2arc_log_blkptr_valid(dev, lb_ptr_buf->lb_ptr)) {
8732 vdev_space_update(vd, -asize, 0, 0);
8733 ARCSTAT_INCR(arcstat_l2_log_blk_asize, -asize);
8734 ARCSTAT_BUMPDOWN(arcstat_l2_log_blk_count);
8735 zfs_refcount_remove_many(&dev->l2ad_lb_asize, asize,
8737 zfs_refcount_remove(&dev->l2ad_lb_count, lb_ptr_buf);
8738 list_remove(&dev->l2ad_lbptr_list, lb_ptr_buf);
8739 kmem_free(lb_ptr_buf->lb_ptr,
8740 sizeof (l2arc_log_blkptr_t));
8741 kmem_free(lb_ptr_buf, sizeof (l2arc_lb_ptr_buf_t));
8745 for (hdr = list_tail(buflist); hdr; hdr = hdr_prev) {
8746 hdr_prev = list_prev(buflist, hdr);
8748 ASSERT(!HDR_EMPTY(hdr));
8749 hash_lock = HDR_LOCK(hdr);
8752 * We cannot use mutex_enter or else we can deadlock
8753 * with l2arc_write_buffers (due to swapping the order
8754 * the hash lock and l2ad_mtx are taken).
8756 if (!mutex_tryenter(hash_lock)) {
8758 * Missed the hash lock. Retry.
8760 ARCSTAT_BUMP(arcstat_l2_evict_lock_retry);
8761 mutex_exit(&dev->l2ad_mtx);
8762 mutex_enter(hash_lock);
8763 mutex_exit(hash_lock);
8768 * A header can't be on this list if it doesn't have L2 header.
8770 ASSERT(HDR_HAS_L2HDR(hdr));
8772 /* Ensure this header has finished being written. */
8773 ASSERT(!HDR_L2_WRITING(hdr));
8774 ASSERT(!HDR_L2_WRITE_HEAD(hdr));
8776 if (!all && (hdr->b_l2hdr.b_daddr >= dev->l2ad_evict ||
8777 hdr->b_l2hdr.b_daddr < dev->l2ad_hand)) {
8779 * We've evicted to the target address,
8780 * or the end of the device.
8782 mutex_exit(hash_lock);
8786 if (!HDR_HAS_L1HDR(hdr)) {
8787 ASSERT(!HDR_L2_READING(hdr));
8789 * This doesn't exist in the ARC. Destroy.
8790 * arc_hdr_destroy() will call list_remove()
8791 * and decrement arcstat_l2_lsize.
8793 arc_change_state(arc_anon, hdr);
8794 arc_hdr_destroy(hdr);
8796 ASSERT(hdr->b_l1hdr.b_state != arc_l2c_only);
8797 ARCSTAT_BUMP(arcstat_l2_evict_l1cached);
8799 * Invalidate issued or about to be issued
8800 * reads, since we may be about to write
8801 * over this location.
8803 if (HDR_L2_READING(hdr)) {
8804 ARCSTAT_BUMP(arcstat_l2_evict_reading);
8805 arc_hdr_set_flags(hdr, ARC_FLAG_L2_EVICTED);
8808 arc_hdr_l2hdr_destroy(hdr);
8810 mutex_exit(hash_lock);
8812 mutex_exit(&dev->l2ad_mtx);
8816 * We need to check if we evict all buffers, otherwise we may iterate
8819 if (!all && rerun) {
8821 * Bump device hand to the device start if it is approaching the
8822 * end. l2arc_evict() has already evicted ahead for this case.
8824 dev->l2ad_hand = dev->l2ad_start;
8825 dev->l2ad_evict = dev->l2ad_start;
8826 dev->l2ad_first = B_FALSE;
8832 * In case of cache device removal (all) the following
8833 * assertions may be violated without functional consequences
8834 * as the device is about to be removed.
8836 ASSERT3U(dev->l2ad_hand + distance, <, dev->l2ad_end);
8837 if (!dev->l2ad_first)
8838 ASSERT3U(dev->l2ad_hand, <=, dev->l2ad_evict);
8843 * Handle any abd transforms that might be required for writing to the L2ARC.
8844 * If successful, this function will always return an abd with the data
8845 * transformed as it is on disk in a new abd of asize bytes.
8848 l2arc_apply_transforms(spa_t *spa, arc_buf_hdr_t *hdr, uint64_t asize,
8853 abd_t *cabd = NULL, *eabd = NULL, *to_write = hdr->b_l1hdr.b_pabd;
8854 enum zio_compress compress = HDR_GET_COMPRESS(hdr);
8855 uint64_t psize = HDR_GET_PSIZE(hdr);
8856 uint64_t size = arc_hdr_size(hdr);
8857 boolean_t ismd = HDR_ISTYPE_METADATA(hdr);
8858 boolean_t bswap = (hdr->b_l1hdr.b_byteswap != DMU_BSWAP_NUMFUNCS);
8859 dsl_crypto_key_t *dck = NULL;
8860 uint8_t mac[ZIO_DATA_MAC_LEN] = { 0 };
8861 boolean_t no_crypt = B_FALSE;
8863 ASSERT((HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF &&
8864 !HDR_COMPRESSION_ENABLED(hdr)) ||
8865 HDR_ENCRYPTED(hdr) || HDR_SHARED_DATA(hdr) || psize != asize);
8866 ASSERT3U(psize, <=, asize);
8869 * If this data simply needs its own buffer, we simply allocate it
8870 * and copy the data. This may be done to eliminate a dependency on a
8871 * shared buffer or to reallocate the buffer to match asize.
8873 if (HDR_HAS_RABD(hdr) && asize != psize) {
8874 ASSERT3U(asize, >=, psize);
8875 to_write = abd_alloc_for_io(asize, ismd);
8876 abd_copy(to_write, hdr->b_crypt_hdr.b_rabd, psize);
8878 abd_zero_off(to_write, psize, asize - psize);
8882 if ((compress == ZIO_COMPRESS_OFF || HDR_COMPRESSION_ENABLED(hdr)) &&
8883 !HDR_ENCRYPTED(hdr)) {
8884 ASSERT3U(size, ==, psize);
8885 to_write = abd_alloc_for_io(asize, ismd);
8886 abd_copy(to_write, hdr->b_l1hdr.b_pabd, size);
8888 abd_zero_off(to_write, size, asize - size);
8892 if (compress != ZIO_COMPRESS_OFF && !HDR_COMPRESSION_ENABLED(hdr)) {
8894 * In some cases, we can wind up with size > asize, so
8895 * we need to opt for the larger allocation option here.
8897 * (We also need abd_return_buf_copy in all cases because
8898 * it's an ASSERT() to modify the buffer before returning it
8899 * with arc_return_buf(), and all the compressors
8900 * write things before deciding to fail compression in nearly
8903 uint64_t bufsize = MAX(size, asize);
8904 cabd = abd_alloc_for_io(bufsize, ismd);
8905 tmp = abd_borrow_buf(cabd, bufsize);
8907 psize = zio_compress_data(compress, to_write, &tmp, size,
8910 if (psize >= asize) {
8911 psize = HDR_GET_PSIZE(hdr);
8912 abd_return_buf_copy(cabd, tmp, bufsize);
8913 HDR_SET_COMPRESS(hdr, ZIO_COMPRESS_OFF);
8915 abd_copy(to_write, hdr->b_l1hdr.b_pabd, psize);
8917 abd_zero_off(to_write, psize, asize - psize);
8920 ASSERT3U(psize, <=, HDR_GET_PSIZE(hdr));
8922 memset((char *)tmp + psize, 0, bufsize - psize);
8923 psize = HDR_GET_PSIZE(hdr);
8924 abd_return_buf_copy(cabd, tmp, bufsize);
8929 if (HDR_ENCRYPTED(hdr)) {
8930 eabd = abd_alloc_for_io(asize, ismd);
8933 * If the dataset was disowned before the buffer
8934 * made it to this point, the key to re-encrypt
8935 * it won't be available. In this case we simply
8936 * won't write the buffer to the L2ARC.
8938 ret = spa_keystore_lookup_key(spa, hdr->b_crypt_hdr.b_dsobj,
8943 ret = zio_do_crypt_abd(B_TRUE, &dck->dck_key,
8944 hdr->b_crypt_hdr.b_ot, bswap, hdr->b_crypt_hdr.b_salt,
8945 hdr->b_crypt_hdr.b_iv, mac, psize, to_write, eabd,
8951 abd_copy(eabd, to_write, psize);
8954 abd_zero_off(eabd, psize, asize - psize);
8956 /* assert that the MAC we got here matches the one we saved */
8957 ASSERT0(memcmp(mac, hdr->b_crypt_hdr.b_mac, ZIO_DATA_MAC_LEN));
8958 spa_keystore_dsl_key_rele(spa, dck, FTAG);
8960 if (to_write == cabd)
8967 ASSERT3P(to_write, !=, hdr->b_l1hdr.b_pabd);
8968 *abd_out = to_write;
8973 spa_keystore_dsl_key_rele(spa, dck, FTAG);
8984 l2arc_blk_fetch_done(zio_t *zio)
8986 l2arc_read_callback_t *cb;
8988 cb = zio->io_private;
8989 if (cb->l2rcb_abd != NULL)
8990 abd_free(cb->l2rcb_abd);
8991 kmem_free(cb, sizeof (l2arc_read_callback_t));
8995 * Find and write ARC buffers to the L2ARC device.
8997 * An ARC_FLAG_L2_WRITING flag is set so that the L2ARC buffers are not valid
8998 * for reading until they have completed writing.
8999 * The headroom_boost is an in-out parameter used to maintain headroom boost
9000 * state between calls to this function.
9002 * Returns the number of bytes actually written (which may be smaller than
9003 * the delta by which the device hand has changed due to alignment and the
9004 * writing of log blocks).
9007 l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz)
9009 arc_buf_hdr_t *hdr, *hdr_prev, *head;
9010 uint64_t write_asize, write_psize, write_lsize, headroom;
9012 l2arc_write_callback_t *cb = NULL;
9014 uint64_t guid = spa_load_guid(spa);
9015 l2arc_dev_hdr_phys_t *l2dhdr = dev->l2ad_dev_hdr;
9017 ASSERT3P(dev->l2ad_vdev, !=, NULL);
9020 write_lsize = write_asize = write_psize = 0;
9022 head = kmem_cache_alloc(hdr_l2only_cache, KM_PUSHPAGE);
9023 arc_hdr_set_flags(head, ARC_FLAG_L2_WRITE_HEAD | ARC_FLAG_HAS_L2HDR);
9026 * Copy buffers for L2ARC writing.
9028 for (int pass = 0; pass < L2ARC_FEED_TYPES; pass++) {
9030 * If pass == 1 or 3, we cache MRU metadata and data
9033 if (l2arc_mfuonly) {
9034 if (pass == 1 || pass == 3)
9038 multilist_sublist_t *mls = l2arc_sublist_lock(pass);
9039 uint64_t passed_sz = 0;
9041 VERIFY3P(mls, !=, NULL);
9044 * L2ARC fast warmup.
9046 * Until the ARC is warm and starts to evict, read from the
9047 * head of the ARC lists rather than the tail.
9049 if (arc_warm == B_FALSE)
9050 hdr = multilist_sublist_head(mls);
9052 hdr = multilist_sublist_tail(mls);
9054 headroom = target_sz * l2arc_headroom;
9055 if (zfs_compressed_arc_enabled)
9056 headroom = (headroom * l2arc_headroom_boost) / 100;
9058 for (; hdr; hdr = hdr_prev) {
9059 kmutex_t *hash_lock;
9060 abd_t *to_write = NULL;
9062 if (arc_warm == B_FALSE)
9063 hdr_prev = multilist_sublist_next(mls, hdr);
9065 hdr_prev = multilist_sublist_prev(mls, hdr);
9067 hash_lock = HDR_LOCK(hdr);
9068 if (!mutex_tryenter(hash_lock)) {
9070 * Skip this buffer rather than waiting.
9075 passed_sz += HDR_GET_LSIZE(hdr);
9076 if (l2arc_headroom != 0 && passed_sz > headroom) {
9080 mutex_exit(hash_lock);
9084 if (!l2arc_write_eligible(guid, hdr)) {
9085 mutex_exit(hash_lock);
9089 ASSERT(HDR_HAS_L1HDR(hdr));
9091 ASSERT3U(HDR_GET_PSIZE(hdr), >, 0);
9092 ASSERT3U(arc_hdr_size(hdr), >, 0);
9093 ASSERT(hdr->b_l1hdr.b_pabd != NULL ||
9095 uint64_t psize = HDR_GET_PSIZE(hdr);
9096 uint64_t asize = vdev_psize_to_asize(dev->l2ad_vdev,
9100 * If the allocated size of this buffer plus the max
9101 * size for the pending log block exceeds the evicted
9102 * target size, terminate writing buffers for this run.
9104 if (write_asize + asize +
9105 sizeof (l2arc_log_blk_phys_t) > target_sz) {
9107 mutex_exit(hash_lock);
9112 * We rely on the L1 portion of the header below, so
9113 * it's invalid for this header to have been evicted out
9114 * of the ghost cache, prior to being written out. The
9115 * ARC_FLAG_L2_WRITING bit ensures this won't happen.
9117 arc_hdr_set_flags(hdr, ARC_FLAG_L2_WRITING);
9120 * If this header has b_rabd, we can use this since it
9121 * must always match the data exactly as it exists on
9122 * disk. Otherwise, the L2ARC can normally use the
9123 * hdr's data, but if we're sharing data between the
9124 * hdr and one of its bufs, L2ARC needs its own copy of
9125 * the data so that the ZIO below can't race with the
9126 * buf consumer. To ensure that this copy will be
9127 * available for the lifetime of the ZIO and be cleaned
9128 * up afterwards, we add it to the l2arc_free_on_write
9129 * queue. If we need to apply any transforms to the
9130 * data (compression, encryption) we will also need the
9133 if (HDR_HAS_RABD(hdr) && psize == asize) {
9134 to_write = hdr->b_crypt_hdr.b_rabd;
9135 } else if ((HDR_COMPRESSION_ENABLED(hdr) ||
9136 HDR_GET_COMPRESS(hdr) == ZIO_COMPRESS_OFF) &&
9137 !HDR_ENCRYPTED(hdr) && !HDR_SHARED_DATA(hdr) &&
9139 to_write = hdr->b_l1hdr.b_pabd;
9142 arc_buf_contents_t type = arc_buf_type(hdr);
9144 ret = l2arc_apply_transforms(spa, hdr, asize,
9147 arc_hdr_clear_flags(hdr,
9148 ARC_FLAG_L2_WRITING);
9149 mutex_exit(hash_lock);
9153 l2arc_free_abd_on_write(to_write, asize, type);
9158 * Insert a dummy header on the buflist so
9159 * l2arc_write_done() can find where the
9160 * write buffers begin without searching.
9162 mutex_enter(&dev->l2ad_mtx);
9163 list_insert_head(&dev->l2ad_buflist, head);
9164 mutex_exit(&dev->l2ad_mtx);
9167 sizeof (l2arc_write_callback_t), KM_SLEEP);
9168 cb->l2wcb_dev = dev;
9169 cb->l2wcb_head = head;
9171 * Create a list to save allocated abd buffers
9172 * for l2arc_log_blk_commit().
9174 list_create(&cb->l2wcb_abd_list,
9175 sizeof (l2arc_lb_abd_buf_t),
9176 offsetof(l2arc_lb_abd_buf_t, node));
9177 pio = zio_root(spa, l2arc_write_done, cb,
9181 hdr->b_l2hdr.b_dev = dev;
9182 hdr->b_l2hdr.b_hits = 0;
9184 hdr->b_l2hdr.b_daddr = dev->l2ad_hand;
9185 hdr->b_l2hdr.b_arcs_state =
9186 hdr->b_l1hdr.b_state->arcs_state;
9187 arc_hdr_set_flags(hdr, ARC_FLAG_HAS_L2HDR);
9189 mutex_enter(&dev->l2ad_mtx);
9190 list_insert_head(&dev->l2ad_buflist, hdr);
9191 mutex_exit(&dev->l2ad_mtx);
9193 (void) zfs_refcount_add_many(&dev->l2ad_alloc,
9194 arc_hdr_size(hdr), hdr);
9196 wzio = zio_write_phys(pio, dev->l2ad_vdev,
9197 hdr->b_l2hdr.b_daddr, asize, to_write,
9198 ZIO_CHECKSUM_OFF, NULL, hdr,
9199 ZIO_PRIORITY_ASYNC_WRITE,
9200 ZIO_FLAG_CANFAIL, B_FALSE);
9202 write_lsize += HDR_GET_LSIZE(hdr);
9203 DTRACE_PROBE2(l2arc__write, vdev_t *, dev->l2ad_vdev,
9206 write_psize += psize;
9207 write_asize += asize;
9208 dev->l2ad_hand += asize;
9209 l2arc_hdr_arcstats_increment(hdr);
9210 vdev_space_update(dev->l2ad_vdev, asize, 0, 0);
9212 mutex_exit(hash_lock);
9215 * Append buf info to current log and commit if full.
9216 * arcstat_l2_{size,asize} kstats are updated
9219 if (l2arc_log_blk_insert(dev, hdr)) {
9221 * l2ad_hand will be adjusted in
9222 * l2arc_log_blk_commit().
9225 l2arc_log_blk_commit(dev, pio, cb);
9231 multilist_sublist_unlock(mls);
9237 /* No buffers selected for writing? */
9239 ASSERT0(write_lsize);
9240 ASSERT(!HDR_HAS_L1HDR(head));
9241 kmem_cache_free(hdr_l2only_cache, head);
9244 * Although we did not write any buffers l2ad_evict may
9247 if (dev->l2ad_evict != l2dhdr->dh_evict)
9248 l2arc_dev_hdr_update(dev);
9253 if (!dev->l2ad_first)
9254 ASSERT3U(dev->l2ad_hand, <=, dev->l2ad_evict);
9256 ASSERT3U(write_asize, <=, target_sz);
9257 ARCSTAT_BUMP(arcstat_l2_writes_sent);
9258 ARCSTAT_INCR(arcstat_l2_write_bytes, write_psize);
9260 dev->l2ad_writing = B_TRUE;
9261 (void) zio_wait(pio);
9262 dev->l2ad_writing = B_FALSE;
9265 * Update the device header after the zio completes as
9266 * l2arc_write_done() may have updated the memory holding the log block
9267 * pointers in the device header.
9269 l2arc_dev_hdr_update(dev);
9271 return (write_asize);
9275 l2arc_hdr_limit_reached(void)
9277 int64_t s = aggsum_upper_bound(&arc_sums.arcstat_l2_hdr_size);
9279 return (arc_reclaim_needed() ||
9280 (s > (arc_warm ? arc_c : arc_c_max) * l2arc_meta_percent / 100));
9284 * This thread feeds the L2ARC at regular intervals. This is the beating
9285 * heart of the L2ARC.
9287 static __attribute__((noreturn)) void
9288 l2arc_feed_thread(void *unused)
9294 uint64_t size, wrote;
9295 clock_t begin, next = ddi_get_lbolt();
9296 fstrans_cookie_t cookie;
9298 CALLB_CPR_INIT(&cpr, &l2arc_feed_thr_lock, callb_generic_cpr, FTAG);
9300 mutex_enter(&l2arc_feed_thr_lock);
9302 cookie = spl_fstrans_mark();
9303 while (l2arc_thread_exit == 0) {
9304 CALLB_CPR_SAFE_BEGIN(&cpr);
9305 (void) cv_timedwait_idle(&l2arc_feed_thr_cv,
9306 &l2arc_feed_thr_lock, next);
9307 CALLB_CPR_SAFE_END(&cpr, &l2arc_feed_thr_lock);
9308 next = ddi_get_lbolt() + hz;
9311 * Quick check for L2ARC devices.
9313 mutex_enter(&l2arc_dev_mtx);
9314 if (l2arc_ndev == 0) {
9315 mutex_exit(&l2arc_dev_mtx);
9318 mutex_exit(&l2arc_dev_mtx);
9319 begin = ddi_get_lbolt();
9322 * This selects the next l2arc device to write to, and in
9323 * doing so the next spa to feed from: dev->l2ad_spa. This
9324 * will return NULL if there are now no l2arc devices or if
9325 * they are all faulted.
9327 * If a device is returned, its spa's config lock is also
9328 * held to prevent device removal. l2arc_dev_get_next()
9329 * will grab and release l2arc_dev_mtx.
9331 if ((dev = l2arc_dev_get_next()) == NULL)
9334 spa = dev->l2ad_spa;
9335 ASSERT3P(spa, !=, NULL);
9338 * If the pool is read-only then force the feed thread to
9339 * sleep a little longer.
9341 if (!spa_writeable(spa)) {
9342 next = ddi_get_lbolt() + 5 * l2arc_feed_secs * hz;
9343 spa_config_exit(spa, SCL_L2ARC, dev);
9348 * Avoid contributing to memory pressure.
9350 if (l2arc_hdr_limit_reached()) {
9351 ARCSTAT_BUMP(arcstat_l2_abort_lowmem);
9352 spa_config_exit(spa, SCL_L2ARC, dev);
9356 ARCSTAT_BUMP(arcstat_l2_feeds);
9358 size = l2arc_write_size(dev);
9361 * Evict L2ARC buffers that will be overwritten.
9363 l2arc_evict(dev, size, B_FALSE);
9366 * Write ARC buffers.
9368 wrote = l2arc_write_buffers(spa, dev, size);
9371 * Calculate interval between writes.
9373 next = l2arc_write_interval(begin, size, wrote);
9374 spa_config_exit(spa, SCL_L2ARC, dev);
9376 spl_fstrans_unmark(cookie);
9378 l2arc_thread_exit = 0;
9379 cv_broadcast(&l2arc_feed_thr_cv);
9380 CALLB_CPR_EXIT(&cpr); /* drops l2arc_feed_thr_lock */
9385 l2arc_vdev_present(vdev_t *vd)
9387 return (l2arc_vdev_get(vd) != NULL);
9391 * Returns the l2arc_dev_t associated with a particular vdev_t or NULL if
9392 * the vdev_t isn't an L2ARC device.
9395 l2arc_vdev_get(vdev_t *vd)
9399 mutex_enter(&l2arc_dev_mtx);
9400 for (dev = list_head(l2arc_dev_list); dev != NULL;
9401 dev = list_next(l2arc_dev_list, dev)) {
9402 if (dev->l2ad_vdev == vd)
9405 mutex_exit(&l2arc_dev_mtx);
9411 l2arc_rebuild_dev(l2arc_dev_t *dev, boolean_t reopen)
9413 l2arc_dev_hdr_phys_t *l2dhdr = dev->l2ad_dev_hdr;
9414 uint64_t l2dhdr_asize = dev->l2ad_dev_hdr_asize;
9415 spa_t *spa = dev->l2ad_spa;
9418 * The L2ARC has to hold at least the payload of one log block for
9419 * them to be restored (persistent L2ARC). The payload of a log block
9420 * depends on the amount of its log entries. We always write log blocks
9421 * with 1022 entries. How many of them are committed or restored depends
9422 * on the size of the L2ARC device. Thus the maximum payload of
9423 * one log block is 1022 * SPA_MAXBLOCKSIZE = 16GB. If the L2ARC device
9424 * is less than that, we reduce the amount of committed and restored
9425 * log entries per block so as to enable persistence.
9427 if (dev->l2ad_end < l2arc_rebuild_blocks_min_l2size) {
9428 dev->l2ad_log_entries = 0;
9430 dev->l2ad_log_entries = MIN((dev->l2ad_end -
9431 dev->l2ad_start) >> SPA_MAXBLOCKSHIFT,
9432 L2ARC_LOG_BLK_MAX_ENTRIES);
9436 * Read the device header, if an error is returned do not rebuild L2ARC.
9438 if (l2arc_dev_hdr_read(dev) == 0 && dev->l2ad_log_entries > 0) {
9440 * If we are onlining a cache device (vdev_reopen) that was
9441 * still present (l2arc_vdev_present()) and rebuild is enabled,
9442 * we should evict all ARC buffers and pointers to log blocks
9443 * and reclaim their space before restoring its contents to
9447 if (!l2arc_rebuild_enabled) {
9450 l2arc_evict(dev, 0, B_TRUE);
9451 /* start a new log block */
9452 dev->l2ad_log_ent_idx = 0;
9453 dev->l2ad_log_blk_payload_asize = 0;
9454 dev->l2ad_log_blk_payload_start = 0;
9458 * Just mark the device as pending for a rebuild. We won't
9459 * be starting a rebuild in line here as it would block pool
9460 * import. Instead spa_load_impl will hand that off to an
9461 * async task which will call l2arc_spa_rebuild_start.
9463 dev->l2ad_rebuild = B_TRUE;
9464 } else if (spa_writeable(spa)) {
9466 * In this case TRIM the whole device if l2arc_trim_ahead > 0,
9467 * otherwise create a new header. We zero out the memory holding
9468 * the header to reset dh_start_lbps. If we TRIM the whole
9469 * device the new header will be written by
9470 * vdev_trim_l2arc_thread() at the end of the TRIM to update the
9471 * trim_state in the header too. When reading the header, if
9472 * trim_state is not VDEV_TRIM_COMPLETE and l2arc_trim_ahead > 0
9473 * we opt to TRIM the whole device again.
9475 if (l2arc_trim_ahead > 0) {
9476 dev->l2ad_trim_all = B_TRUE;
9478 memset(l2dhdr, 0, l2dhdr_asize);
9479 l2arc_dev_hdr_update(dev);
9485 * Add a vdev for use by the L2ARC. By this point the spa has already
9486 * validated the vdev and opened it.
9489 l2arc_add_vdev(spa_t *spa, vdev_t *vd)
9491 l2arc_dev_t *adddev;
9492 uint64_t l2dhdr_asize;
9494 ASSERT(!l2arc_vdev_present(vd));
9497 * Create a new l2arc device entry.
9499 adddev = vmem_zalloc(sizeof (l2arc_dev_t), KM_SLEEP);
9500 adddev->l2ad_spa = spa;
9501 adddev->l2ad_vdev = vd;
9502 /* leave extra size for an l2arc device header */
9503 l2dhdr_asize = adddev->l2ad_dev_hdr_asize =
9504 MAX(sizeof (*adddev->l2ad_dev_hdr), 1 << vd->vdev_ashift);
9505 adddev->l2ad_start = VDEV_LABEL_START_SIZE + l2dhdr_asize;
9506 adddev->l2ad_end = VDEV_LABEL_START_SIZE + vdev_get_min_asize(vd);
9507 ASSERT3U(adddev->l2ad_start, <, adddev->l2ad_end);
9508 adddev->l2ad_hand = adddev->l2ad_start;
9509 adddev->l2ad_evict = adddev->l2ad_start;
9510 adddev->l2ad_first = B_TRUE;
9511 adddev->l2ad_writing = B_FALSE;
9512 adddev->l2ad_trim_all = B_FALSE;
9513 list_link_init(&adddev->l2ad_node);
9514 adddev->l2ad_dev_hdr = kmem_zalloc(l2dhdr_asize, KM_SLEEP);
9516 mutex_init(&adddev->l2ad_mtx, NULL, MUTEX_DEFAULT, NULL);
9518 * This is a list of all ARC buffers that are still valid on the
9521 list_create(&adddev->l2ad_buflist, sizeof (arc_buf_hdr_t),
9522 offsetof(arc_buf_hdr_t, b_l2hdr.b_l2node));
9525 * This is a list of pointers to log blocks that are still present
9528 list_create(&adddev->l2ad_lbptr_list, sizeof (l2arc_lb_ptr_buf_t),
9529 offsetof(l2arc_lb_ptr_buf_t, node));
9531 vdev_space_update(vd, 0, 0, adddev->l2ad_end - adddev->l2ad_hand);
9532 zfs_refcount_create(&adddev->l2ad_alloc);
9533 zfs_refcount_create(&adddev->l2ad_lb_asize);
9534 zfs_refcount_create(&adddev->l2ad_lb_count);
9537 * Decide if dev is eligible for L2ARC rebuild or whole device
9538 * trimming. This has to happen before the device is added in the
9539 * cache device list and l2arc_dev_mtx is released. Otherwise
9540 * l2arc_feed_thread() might already start writing on the
9543 l2arc_rebuild_dev(adddev, B_FALSE);
9546 * Add device to global list
9548 mutex_enter(&l2arc_dev_mtx);
9549 list_insert_head(l2arc_dev_list, adddev);
9550 atomic_inc_64(&l2arc_ndev);
9551 mutex_exit(&l2arc_dev_mtx);
9555 * Decide if a vdev is eligible for L2ARC rebuild, called from vdev_reopen()
9556 * in case of onlining a cache device.
9559 l2arc_rebuild_vdev(vdev_t *vd, boolean_t reopen)
9561 l2arc_dev_t *dev = NULL;
9563 dev = l2arc_vdev_get(vd);
9564 ASSERT3P(dev, !=, NULL);
9567 * In contrast to l2arc_add_vdev() we do not have to worry about
9568 * l2arc_feed_thread() invalidating previous content when onlining a
9569 * cache device. The device parameters (l2ad*) are not cleared when
9570 * offlining the device and writing new buffers will not invalidate
9571 * all previous content. In worst case only buffers that have not had
9572 * their log block written to the device will be lost.
9573 * When onlining the cache device (ie offline->online without exporting
9574 * the pool in between) this happens:
9575 * vdev_reopen() -> vdev_open() -> l2arc_rebuild_vdev()
9577 * vdev_is_dead() = B_FALSE l2ad_rebuild = B_TRUE
9578 * During the time where vdev_is_dead = B_FALSE and until l2ad_rebuild
9579 * is set to B_TRUE we might write additional buffers to the device.
9581 l2arc_rebuild_dev(dev, reopen);
9585 * Remove a vdev from the L2ARC.
9588 l2arc_remove_vdev(vdev_t *vd)
9590 l2arc_dev_t *remdev = NULL;
9593 * Find the device by vdev
9595 remdev = l2arc_vdev_get(vd);
9596 ASSERT3P(remdev, !=, NULL);
9599 * Cancel any ongoing or scheduled rebuild.
9601 mutex_enter(&l2arc_rebuild_thr_lock);
9602 if (remdev->l2ad_rebuild_began == B_TRUE) {
9603 remdev->l2ad_rebuild_cancel = B_TRUE;
9604 while (remdev->l2ad_rebuild == B_TRUE)
9605 cv_wait(&l2arc_rebuild_thr_cv, &l2arc_rebuild_thr_lock);
9607 mutex_exit(&l2arc_rebuild_thr_lock);
9610 * Remove device from global list
9612 mutex_enter(&l2arc_dev_mtx);
9613 list_remove(l2arc_dev_list, remdev);
9614 l2arc_dev_last = NULL; /* may have been invalidated */
9615 atomic_dec_64(&l2arc_ndev);
9616 mutex_exit(&l2arc_dev_mtx);
9619 * Clear all buflists and ARC references. L2ARC device flush.
9621 l2arc_evict(remdev, 0, B_TRUE);
9622 list_destroy(&remdev->l2ad_buflist);
9623 ASSERT(list_is_empty(&remdev->l2ad_lbptr_list));
9624 list_destroy(&remdev->l2ad_lbptr_list);
9625 mutex_destroy(&remdev->l2ad_mtx);
9626 zfs_refcount_destroy(&remdev->l2ad_alloc);
9627 zfs_refcount_destroy(&remdev->l2ad_lb_asize);
9628 zfs_refcount_destroy(&remdev->l2ad_lb_count);
9629 kmem_free(remdev->l2ad_dev_hdr, remdev->l2ad_dev_hdr_asize);
9630 vmem_free(remdev, sizeof (l2arc_dev_t));
9636 l2arc_thread_exit = 0;
9639 mutex_init(&l2arc_feed_thr_lock, NULL, MUTEX_DEFAULT, NULL);
9640 cv_init(&l2arc_feed_thr_cv, NULL, CV_DEFAULT, NULL);
9641 mutex_init(&l2arc_rebuild_thr_lock, NULL, MUTEX_DEFAULT, NULL);
9642 cv_init(&l2arc_rebuild_thr_cv, NULL, CV_DEFAULT, NULL);
9643 mutex_init(&l2arc_dev_mtx, NULL, MUTEX_DEFAULT, NULL);
9644 mutex_init(&l2arc_free_on_write_mtx, NULL, MUTEX_DEFAULT, NULL);
9646 l2arc_dev_list = &L2ARC_dev_list;
9647 l2arc_free_on_write = &L2ARC_free_on_write;
9648 list_create(l2arc_dev_list, sizeof (l2arc_dev_t),
9649 offsetof(l2arc_dev_t, l2ad_node));
9650 list_create(l2arc_free_on_write, sizeof (l2arc_data_free_t),
9651 offsetof(l2arc_data_free_t, l2df_list_node));
9657 mutex_destroy(&l2arc_feed_thr_lock);
9658 cv_destroy(&l2arc_feed_thr_cv);
9659 mutex_destroy(&l2arc_rebuild_thr_lock);
9660 cv_destroy(&l2arc_rebuild_thr_cv);
9661 mutex_destroy(&l2arc_dev_mtx);
9662 mutex_destroy(&l2arc_free_on_write_mtx);
9664 list_destroy(l2arc_dev_list);
9665 list_destroy(l2arc_free_on_write);
9671 if (!(spa_mode_global & SPA_MODE_WRITE))
9674 (void) thread_create(NULL, 0, l2arc_feed_thread, NULL, 0, &p0,
9675 TS_RUN, defclsyspri);
9681 if (!(spa_mode_global & SPA_MODE_WRITE))
9684 mutex_enter(&l2arc_feed_thr_lock);
9685 cv_signal(&l2arc_feed_thr_cv); /* kick thread out of startup */
9686 l2arc_thread_exit = 1;
9687 while (l2arc_thread_exit != 0)
9688 cv_wait(&l2arc_feed_thr_cv, &l2arc_feed_thr_lock);
9689 mutex_exit(&l2arc_feed_thr_lock);
9693 * Punches out rebuild threads for the L2ARC devices in a spa. This should
9694 * be called after pool import from the spa async thread, since starting
9695 * these threads directly from spa_import() will make them part of the
9696 * "zpool import" context and delay process exit (and thus pool import).
9699 l2arc_spa_rebuild_start(spa_t *spa)
9701 ASSERT(MUTEX_HELD(&spa_namespace_lock));
9704 * Locate the spa's l2arc devices and kick off rebuild threads.
9706 for (int i = 0; i < spa->spa_l2cache.sav_count; i++) {
9708 l2arc_vdev_get(spa->spa_l2cache.sav_vdevs[i]);
9710 /* Don't attempt a rebuild if the vdev is UNAVAIL */
9713 mutex_enter(&l2arc_rebuild_thr_lock);
9714 if (dev->l2ad_rebuild && !dev->l2ad_rebuild_cancel) {
9715 dev->l2ad_rebuild_began = B_TRUE;
9716 (void) thread_create(NULL, 0, l2arc_dev_rebuild_thread,
9717 dev, 0, &p0, TS_RUN, minclsyspri);
9719 mutex_exit(&l2arc_rebuild_thr_lock);
9724 * Main entry point for L2ARC rebuilding.
9726 static __attribute__((noreturn)) void
9727 l2arc_dev_rebuild_thread(void *arg)
9729 l2arc_dev_t *dev = arg;
9731 VERIFY(!dev->l2ad_rebuild_cancel);
9732 VERIFY(dev->l2ad_rebuild);
9733 (void) l2arc_rebuild(dev);
9734 mutex_enter(&l2arc_rebuild_thr_lock);
9735 dev->l2ad_rebuild_began = B_FALSE;
9736 dev->l2ad_rebuild = B_FALSE;
9737 mutex_exit(&l2arc_rebuild_thr_lock);
9743 * This function implements the actual L2ARC metadata rebuild. It:
9744 * starts reading the log block chain and restores each block's contents
9745 * to memory (reconstructing arc_buf_hdr_t's).
9747 * Operation stops under any of the following conditions:
9749 * 1) We reach the end of the log block chain.
9750 * 2) We encounter *any* error condition (cksum errors, io errors)
9753 l2arc_rebuild(l2arc_dev_t *dev)
9755 vdev_t *vd = dev->l2ad_vdev;
9756 spa_t *spa = vd->vdev_spa;
9758 l2arc_dev_hdr_phys_t *l2dhdr = dev->l2ad_dev_hdr;
9759 l2arc_log_blk_phys_t *this_lb, *next_lb;
9760 zio_t *this_io = NULL, *next_io = NULL;
9761 l2arc_log_blkptr_t lbps[2];
9762 l2arc_lb_ptr_buf_t *lb_ptr_buf;
9763 boolean_t lock_held;
9765 this_lb = vmem_zalloc(sizeof (*this_lb), KM_SLEEP);
9766 next_lb = vmem_zalloc(sizeof (*next_lb), KM_SLEEP);
9769 * We prevent device removal while issuing reads to the device,
9770 * then during the rebuilding phases we drop this lock again so
9771 * that a spa_unload or device remove can be initiated - this is
9772 * safe, because the spa will signal us to stop before removing
9773 * our device and wait for us to stop.
9775 spa_config_enter(spa, SCL_L2ARC, vd, RW_READER);
9779 * Retrieve the persistent L2ARC device state.
9780 * L2BLK_GET_PSIZE returns aligned size for log blocks.
9782 dev->l2ad_evict = MAX(l2dhdr->dh_evict, dev->l2ad_start);
9783 dev->l2ad_hand = MAX(l2dhdr->dh_start_lbps[0].lbp_daddr +
9784 L2BLK_GET_PSIZE((&l2dhdr->dh_start_lbps[0])->lbp_prop),
9786 dev->l2ad_first = !!(l2dhdr->dh_flags & L2ARC_DEV_HDR_EVICT_FIRST);
9788 vd->vdev_trim_action_time = l2dhdr->dh_trim_action_time;
9789 vd->vdev_trim_state = l2dhdr->dh_trim_state;
9792 * In case the zfs module parameter l2arc_rebuild_enabled is false
9793 * we do not start the rebuild process.
9795 if (!l2arc_rebuild_enabled)
9798 /* Prepare the rebuild process */
9799 memcpy(lbps, l2dhdr->dh_start_lbps, sizeof (lbps));
9801 /* Start the rebuild process */
9803 if (!l2arc_log_blkptr_valid(dev, &lbps[0]))
9806 if ((err = l2arc_log_blk_read(dev, &lbps[0], &lbps[1],
9807 this_lb, next_lb, this_io, &next_io)) != 0)
9811 * Our memory pressure valve. If the system is running low
9812 * on memory, rather than swamping memory with new ARC buf
9813 * hdrs, we opt not to rebuild the L2ARC. At this point,
9814 * however, we have already set up our L2ARC dev to chain in
9815 * new metadata log blocks, so the user may choose to offline/
9816 * online the L2ARC dev at a later time (or re-import the pool)
9817 * to reconstruct it (when there's less memory pressure).
9819 if (l2arc_hdr_limit_reached()) {
9820 ARCSTAT_BUMP(arcstat_l2_rebuild_abort_lowmem);
9821 cmn_err(CE_NOTE, "System running low on memory, "
9822 "aborting L2ARC rebuild.");
9823 err = SET_ERROR(ENOMEM);
9827 spa_config_exit(spa, SCL_L2ARC, vd);
9828 lock_held = B_FALSE;
9831 * Now that we know that the next_lb checks out alright, we
9832 * can start reconstruction from this log block.
9833 * L2BLK_GET_PSIZE returns aligned size for log blocks.
9835 uint64_t asize = L2BLK_GET_PSIZE((&lbps[0])->lbp_prop);
9836 l2arc_log_blk_restore(dev, this_lb, asize);
9839 * log block restored, include its pointer in the list of
9840 * pointers to log blocks present in the L2ARC device.
9842 lb_ptr_buf = kmem_zalloc(sizeof (l2arc_lb_ptr_buf_t), KM_SLEEP);
9843 lb_ptr_buf->lb_ptr = kmem_zalloc(sizeof (l2arc_log_blkptr_t),
9845 memcpy(lb_ptr_buf->lb_ptr, &lbps[0],
9846 sizeof (l2arc_log_blkptr_t));
9847 mutex_enter(&dev->l2ad_mtx);
9848 list_insert_tail(&dev->l2ad_lbptr_list, lb_ptr_buf);
9849 ARCSTAT_INCR(arcstat_l2_log_blk_asize, asize);
9850 ARCSTAT_BUMP(arcstat_l2_log_blk_count);
9851 zfs_refcount_add_many(&dev->l2ad_lb_asize, asize, lb_ptr_buf);
9852 zfs_refcount_add(&dev->l2ad_lb_count, lb_ptr_buf);
9853 mutex_exit(&dev->l2ad_mtx);
9854 vdev_space_update(vd, asize, 0, 0);
9857 * Protection against loops of log blocks:
9859 * l2ad_hand l2ad_evict
9861 * l2ad_start |=======================================| l2ad_end
9862 * -----|||----|||---|||----|||
9864 * ---|||---|||----|||---|||
9867 * In this situation the pointer of log block (4) passes
9868 * l2arc_log_blkptr_valid() but the log block should not be
9869 * restored as it is overwritten by the payload of log block
9870 * (0). Only log blocks (0)-(3) should be restored. We check
9871 * whether l2ad_evict lies in between the payload starting
9872 * offset of the next log block (lbps[1].lbp_payload_start)
9873 * and the payload starting offset of the present log block
9874 * (lbps[0].lbp_payload_start). If true and this isn't the
9875 * first pass, we are looping from the beginning and we should
9878 if (l2arc_range_check_overlap(lbps[1].lbp_payload_start,
9879 lbps[0].lbp_payload_start, dev->l2ad_evict) &&
9883 kpreempt(KPREEMPT_SYNC);
9885 mutex_enter(&l2arc_rebuild_thr_lock);
9886 if (dev->l2ad_rebuild_cancel) {
9887 dev->l2ad_rebuild = B_FALSE;
9888 cv_signal(&l2arc_rebuild_thr_cv);
9889 mutex_exit(&l2arc_rebuild_thr_lock);
9890 err = SET_ERROR(ECANCELED);
9893 mutex_exit(&l2arc_rebuild_thr_lock);
9894 if (spa_config_tryenter(spa, SCL_L2ARC, vd,
9900 * L2ARC config lock held by somebody in writer,
9901 * possibly due to them trying to remove us. They'll
9902 * likely to want us to shut down, so after a little
9903 * delay, we check l2ad_rebuild_cancel and retry
9910 * Continue with the next log block.
9913 lbps[1] = this_lb->lb_prev_lbp;
9914 PTR_SWAP(this_lb, next_lb);
9919 if (this_io != NULL)
9920 l2arc_log_blk_fetch_abort(this_io);
9922 if (next_io != NULL)
9923 l2arc_log_blk_fetch_abort(next_io);
9924 vmem_free(this_lb, sizeof (*this_lb));
9925 vmem_free(next_lb, sizeof (*next_lb));
9927 if (!l2arc_rebuild_enabled) {
9928 spa_history_log_internal(spa, "L2ARC rebuild", NULL,
9930 } else if (err == 0 && zfs_refcount_count(&dev->l2ad_lb_count) > 0) {
9931 ARCSTAT_BUMP(arcstat_l2_rebuild_success);
9932 spa_history_log_internal(spa, "L2ARC rebuild", NULL,
9933 "successful, restored %llu blocks",
9934 (u_longlong_t)zfs_refcount_count(&dev->l2ad_lb_count));
9935 } else if (err == 0 && zfs_refcount_count(&dev->l2ad_lb_count) == 0) {
9937 * No error but also nothing restored, meaning the lbps array
9938 * in the device header points to invalid/non-present log
9939 * blocks. Reset the header.
9941 spa_history_log_internal(spa, "L2ARC rebuild", NULL,
9942 "no valid log blocks");
9943 memset(l2dhdr, 0, dev->l2ad_dev_hdr_asize);
9944 l2arc_dev_hdr_update(dev);
9945 } else if (err == ECANCELED) {
9947 * In case the rebuild was canceled do not log to spa history
9948 * log as the pool may be in the process of being removed.
9950 zfs_dbgmsg("L2ARC rebuild aborted, restored %llu blocks",
9951 (u_longlong_t)zfs_refcount_count(&dev->l2ad_lb_count));
9952 } else if (err != 0) {
9953 spa_history_log_internal(spa, "L2ARC rebuild", NULL,
9954 "aborted, restored %llu blocks",
9955 (u_longlong_t)zfs_refcount_count(&dev->l2ad_lb_count));
9959 spa_config_exit(spa, SCL_L2ARC, vd);
9965 * Attempts to read the device header on the provided L2ARC device and writes
9966 * it to `hdr'. On success, this function returns 0, otherwise the appropriate
9967 * error code is returned.
9970 l2arc_dev_hdr_read(l2arc_dev_t *dev)
9974 l2arc_dev_hdr_phys_t *l2dhdr = dev->l2ad_dev_hdr;
9975 const uint64_t l2dhdr_asize = dev->l2ad_dev_hdr_asize;
9978 guid = spa_guid(dev->l2ad_vdev->vdev_spa);
9980 abd = abd_get_from_buf(l2dhdr, l2dhdr_asize);
9982 err = zio_wait(zio_read_phys(NULL, dev->l2ad_vdev,
9983 VDEV_LABEL_START_SIZE, l2dhdr_asize, abd,
9984 ZIO_CHECKSUM_LABEL, NULL, NULL, ZIO_PRIORITY_SYNC_READ,
9985 ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_PROPAGATE | ZIO_FLAG_DONT_RETRY |
9986 ZIO_FLAG_SPECULATIVE, B_FALSE));
9991 ARCSTAT_BUMP(arcstat_l2_rebuild_abort_dh_errors);
9992 zfs_dbgmsg("L2ARC IO error (%d) while reading device header, "
9993 "vdev guid: %llu", err,
9994 (u_longlong_t)dev->l2ad_vdev->vdev_guid);
9998 if (l2dhdr->dh_magic == BSWAP_64(L2ARC_DEV_HDR_MAGIC))
9999 byteswap_uint64_array(l2dhdr, sizeof (*l2dhdr));
10001 if (l2dhdr->dh_magic != L2ARC_DEV_HDR_MAGIC ||
10002 l2dhdr->dh_spa_guid != guid ||
10003 l2dhdr->dh_vdev_guid != dev->l2ad_vdev->vdev_guid ||
10004 l2dhdr->dh_version != L2ARC_PERSISTENT_VERSION ||
10005 l2dhdr->dh_log_entries != dev->l2ad_log_entries ||
10006 l2dhdr->dh_end != dev->l2ad_end ||
10007 !l2arc_range_check_overlap(dev->l2ad_start, dev->l2ad_end,
10008 l2dhdr->dh_evict) ||
10009 (l2dhdr->dh_trim_state != VDEV_TRIM_COMPLETE &&
10010 l2arc_trim_ahead > 0)) {
10012 * Attempt to rebuild a device containing no actual dev hdr
10013 * or containing a header from some other pool or from another
10014 * version of persistent L2ARC.
10016 ARCSTAT_BUMP(arcstat_l2_rebuild_abort_unsupported);
10017 return (SET_ERROR(ENOTSUP));
10024 * Reads L2ARC log blocks from storage and validates their contents.
10026 * This function implements a simple fetcher to make sure that while
10027 * we're processing one buffer the L2ARC is already fetching the next
10028 * one in the chain.
10030 * The arguments this_lp and next_lp point to the current and next log block
10031 * address in the block chain. Similarly, this_lb and next_lb hold the
10032 * l2arc_log_blk_phys_t's of the current and next L2ARC blk.
10034 * The `this_io' and `next_io' arguments are used for block fetching.
10035 * When issuing the first blk IO during rebuild, you should pass NULL for
10036 * `this_io'. This function will then issue a sync IO to read the block and
10037 * also issue an async IO to fetch the next block in the block chain. The
10038 * fetched IO is returned in `next_io'. On subsequent calls to this
10039 * function, pass the value returned in `next_io' from the previous call
10040 * as `this_io' and a fresh `next_io' pointer to hold the next fetch IO.
10041 * Prior to the call, you should initialize your `next_io' pointer to be
10042 * NULL. If no fetch IO was issued, the pointer is left set at NULL.
10044 * On success, this function returns 0, otherwise it returns an appropriate
10045 * error code. On error the fetching IO is aborted and cleared before
10046 * returning from this function. Therefore, if we return `success', the
10047 * caller can assume that we have taken care of cleanup of fetch IOs.
10050 l2arc_log_blk_read(l2arc_dev_t *dev,
10051 const l2arc_log_blkptr_t *this_lbp, const l2arc_log_blkptr_t *next_lbp,
10052 l2arc_log_blk_phys_t *this_lb, l2arc_log_blk_phys_t *next_lb,
10053 zio_t *this_io, zio_t **next_io)
10060 ASSERT(this_lbp != NULL && next_lbp != NULL);
10061 ASSERT(this_lb != NULL && next_lb != NULL);
10062 ASSERT(next_io != NULL && *next_io == NULL);
10063 ASSERT(l2arc_log_blkptr_valid(dev, this_lbp));
10066 * Check to see if we have issued the IO for this log block in a
10067 * previous run. If not, this is the first call, so issue it now.
10069 if (this_io == NULL) {
10070 this_io = l2arc_log_blk_fetch(dev->l2ad_vdev, this_lbp,
10075 * Peek to see if we can start issuing the next IO immediately.
10077 if (l2arc_log_blkptr_valid(dev, next_lbp)) {
10079 * Start issuing IO for the next log block early - this
10080 * should help keep the L2ARC device busy while we
10081 * decompress and restore this log block.
10083 *next_io = l2arc_log_blk_fetch(dev->l2ad_vdev, next_lbp,
10087 /* Wait for the IO to read this log block to complete */
10088 if ((err = zio_wait(this_io)) != 0) {
10089 ARCSTAT_BUMP(arcstat_l2_rebuild_abort_io_errors);
10090 zfs_dbgmsg("L2ARC IO error (%d) while reading log block, "
10091 "offset: %llu, vdev guid: %llu", err,
10092 (u_longlong_t)this_lbp->lbp_daddr,
10093 (u_longlong_t)dev->l2ad_vdev->vdev_guid);
10098 * Make sure the buffer checks out.
10099 * L2BLK_GET_PSIZE returns aligned size for log blocks.
10101 asize = L2BLK_GET_PSIZE((this_lbp)->lbp_prop);
10102 fletcher_4_native(this_lb, asize, NULL, &cksum);
10103 if (!ZIO_CHECKSUM_EQUAL(cksum, this_lbp->lbp_cksum)) {
10104 ARCSTAT_BUMP(arcstat_l2_rebuild_abort_cksum_lb_errors);
10105 zfs_dbgmsg("L2ARC log block cksum failed, offset: %llu, "
10106 "vdev guid: %llu, l2ad_hand: %llu, l2ad_evict: %llu",
10107 (u_longlong_t)this_lbp->lbp_daddr,
10108 (u_longlong_t)dev->l2ad_vdev->vdev_guid,
10109 (u_longlong_t)dev->l2ad_hand,
10110 (u_longlong_t)dev->l2ad_evict);
10111 err = SET_ERROR(ECKSUM);
10115 /* Now we can take our time decoding this buffer */
10116 switch (L2BLK_GET_COMPRESS((this_lbp)->lbp_prop)) {
10117 case ZIO_COMPRESS_OFF:
10119 case ZIO_COMPRESS_LZ4:
10120 abd = abd_alloc_for_io(asize, B_TRUE);
10121 abd_copy_from_buf_off(abd, this_lb, 0, asize);
10122 if ((err = zio_decompress_data(
10123 L2BLK_GET_COMPRESS((this_lbp)->lbp_prop),
10124 abd, this_lb, asize, sizeof (*this_lb), NULL)) != 0) {
10125 err = SET_ERROR(EINVAL);
10130 err = SET_ERROR(EINVAL);
10133 if (this_lb->lb_magic == BSWAP_64(L2ARC_LOG_BLK_MAGIC))
10134 byteswap_uint64_array(this_lb, sizeof (*this_lb));
10135 if (this_lb->lb_magic != L2ARC_LOG_BLK_MAGIC) {
10136 err = SET_ERROR(EINVAL);
10140 /* Abort an in-flight fetch I/O in case of error */
10141 if (err != 0 && *next_io != NULL) {
10142 l2arc_log_blk_fetch_abort(*next_io);
10151 * Restores the payload of a log block to ARC. This creates empty ARC hdr
10152 * entries which only contain an l2arc hdr, essentially restoring the
10153 * buffers to their L2ARC evicted state. This function also updates space
10154 * usage on the L2ARC vdev to make sure it tracks restored buffers.
10157 l2arc_log_blk_restore(l2arc_dev_t *dev, const l2arc_log_blk_phys_t *lb,
10160 uint64_t size = 0, asize = 0;
10161 uint64_t log_entries = dev->l2ad_log_entries;
10164 * Usually arc_adapt() is called only for data, not headers, but
10165 * since we may allocate significant amount of memory here, let ARC
10168 arc_adapt(log_entries * HDR_L2ONLY_SIZE);
10170 for (int i = log_entries - 1; i >= 0; i--) {
10172 * Restore goes in the reverse temporal direction to preserve
10173 * correct temporal ordering of buffers in the l2ad_buflist.
10174 * l2arc_hdr_restore also does a list_insert_tail instead of
10175 * list_insert_head on the l2ad_buflist:
10177 * LIST l2ad_buflist LIST
10178 * HEAD <------ (time) ------ TAIL
10179 * direction +-----+-----+-----+-----+-----+ direction
10180 * of l2arc <== | buf | buf | buf | buf | buf | ===> of rebuild
10181 * fill +-----+-----+-----+-----+-----+
10185 * l2arc_feed_thread l2arc_rebuild
10186 * will place new bufs here restores bufs here
10188 * During l2arc_rebuild() the device is not used by
10189 * l2arc_feed_thread() as dev->l2ad_rebuild is set to true.
10191 size += L2BLK_GET_LSIZE((&lb->lb_entries[i])->le_prop);
10192 asize += vdev_psize_to_asize(dev->l2ad_vdev,
10193 L2BLK_GET_PSIZE((&lb->lb_entries[i])->le_prop));
10194 l2arc_hdr_restore(&lb->lb_entries[i], dev);
10198 * Record rebuild stats:
10199 * size Logical size of restored buffers in the L2ARC
10200 * asize Aligned size of restored buffers in the L2ARC
10202 ARCSTAT_INCR(arcstat_l2_rebuild_size, size);
10203 ARCSTAT_INCR(arcstat_l2_rebuild_asize, asize);
10204 ARCSTAT_INCR(arcstat_l2_rebuild_bufs, log_entries);
10205 ARCSTAT_F_AVG(arcstat_l2_log_blk_avg_asize, lb_asize);
10206 ARCSTAT_F_AVG(arcstat_l2_data_to_meta_ratio, asize / lb_asize);
10207 ARCSTAT_BUMP(arcstat_l2_rebuild_log_blks);
10211 * Restores a single ARC buf hdr from a log entry. The ARC buffer is put
10212 * into a state indicating that it has been evicted to L2ARC.
10215 l2arc_hdr_restore(const l2arc_log_ent_phys_t *le, l2arc_dev_t *dev)
10217 arc_buf_hdr_t *hdr, *exists;
10218 kmutex_t *hash_lock;
10219 arc_buf_contents_t type = L2BLK_GET_TYPE((le)->le_prop);
10223 * Do all the allocation before grabbing any locks, this lets us
10224 * sleep if memory is full and we don't have to deal with failed
10227 hdr = arc_buf_alloc_l2only(L2BLK_GET_LSIZE((le)->le_prop), type,
10228 dev, le->le_dva, le->le_daddr,
10229 L2BLK_GET_PSIZE((le)->le_prop), le->le_birth,
10230 L2BLK_GET_COMPRESS((le)->le_prop), le->le_complevel,
10231 L2BLK_GET_PROTECTED((le)->le_prop),
10232 L2BLK_GET_PREFETCH((le)->le_prop),
10233 L2BLK_GET_STATE((le)->le_prop));
10234 asize = vdev_psize_to_asize(dev->l2ad_vdev,
10235 L2BLK_GET_PSIZE((le)->le_prop));
10238 * vdev_space_update() has to be called before arc_hdr_destroy() to
10239 * avoid underflow since the latter also calls vdev_space_update().
10241 l2arc_hdr_arcstats_increment(hdr);
10242 vdev_space_update(dev->l2ad_vdev, asize, 0, 0);
10244 mutex_enter(&dev->l2ad_mtx);
10245 list_insert_tail(&dev->l2ad_buflist, hdr);
10246 (void) zfs_refcount_add_many(&dev->l2ad_alloc, arc_hdr_size(hdr), hdr);
10247 mutex_exit(&dev->l2ad_mtx);
10249 exists = buf_hash_insert(hdr, &hash_lock);
10251 /* Buffer was already cached, no need to restore it. */
10252 arc_hdr_destroy(hdr);
10254 * If the buffer is already cached, check whether it has
10255 * L2ARC metadata. If not, enter them and update the flag.
10256 * This is important is case of onlining a cache device, since
10257 * we previously evicted all L2ARC metadata from ARC.
10259 if (!HDR_HAS_L2HDR(exists)) {
10260 arc_hdr_set_flags(exists, ARC_FLAG_HAS_L2HDR);
10261 exists->b_l2hdr.b_dev = dev;
10262 exists->b_l2hdr.b_daddr = le->le_daddr;
10263 exists->b_l2hdr.b_arcs_state =
10264 L2BLK_GET_STATE((le)->le_prop);
10265 mutex_enter(&dev->l2ad_mtx);
10266 list_insert_tail(&dev->l2ad_buflist, exists);
10267 (void) zfs_refcount_add_many(&dev->l2ad_alloc,
10268 arc_hdr_size(exists), exists);
10269 mutex_exit(&dev->l2ad_mtx);
10270 l2arc_hdr_arcstats_increment(exists);
10271 vdev_space_update(dev->l2ad_vdev, asize, 0, 0);
10273 ARCSTAT_BUMP(arcstat_l2_rebuild_bufs_precached);
10276 mutex_exit(hash_lock);
10280 * Starts an asynchronous read IO to read a log block. This is used in log
10281 * block reconstruction to start reading the next block before we are done
10282 * decoding and reconstructing the current block, to keep the l2arc device
10283 * nice and hot with read IO to process.
10284 * The returned zio will contain a newly allocated memory buffers for the IO
10285 * data which should then be freed by the caller once the zio is no longer
10286 * needed (i.e. due to it having completed). If you wish to abort this
10287 * zio, you should do so using l2arc_log_blk_fetch_abort, which takes
10288 * care of disposing of the allocated buffers correctly.
10291 l2arc_log_blk_fetch(vdev_t *vd, const l2arc_log_blkptr_t *lbp,
10292 l2arc_log_blk_phys_t *lb)
10296 l2arc_read_callback_t *cb;
10298 /* L2BLK_GET_PSIZE returns aligned size for log blocks */
10299 asize = L2BLK_GET_PSIZE((lbp)->lbp_prop);
10300 ASSERT(asize <= sizeof (l2arc_log_blk_phys_t));
10302 cb = kmem_zalloc(sizeof (l2arc_read_callback_t), KM_SLEEP);
10303 cb->l2rcb_abd = abd_get_from_buf(lb, asize);
10304 pio = zio_root(vd->vdev_spa, l2arc_blk_fetch_done, cb,
10305 ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_PROPAGATE | ZIO_FLAG_DONT_RETRY);
10306 (void) zio_nowait(zio_read_phys(pio, vd, lbp->lbp_daddr, asize,
10307 cb->l2rcb_abd, ZIO_CHECKSUM_OFF, NULL, NULL,
10308 ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL |
10309 ZIO_FLAG_DONT_PROPAGATE | ZIO_FLAG_DONT_RETRY, B_FALSE));
10315 * Aborts a zio returned from l2arc_log_blk_fetch and frees the data
10316 * buffers allocated for it.
10319 l2arc_log_blk_fetch_abort(zio_t *zio)
10321 (void) zio_wait(zio);
10325 * Creates a zio to update the device header on an l2arc device.
10328 l2arc_dev_hdr_update(l2arc_dev_t *dev)
10330 l2arc_dev_hdr_phys_t *l2dhdr = dev->l2ad_dev_hdr;
10331 const uint64_t l2dhdr_asize = dev->l2ad_dev_hdr_asize;
10335 VERIFY(spa_config_held(dev->l2ad_spa, SCL_STATE_ALL, RW_READER));
10337 l2dhdr->dh_magic = L2ARC_DEV_HDR_MAGIC;
10338 l2dhdr->dh_version = L2ARC_PERSISTENT_VERSION;
10339 l2dhdr->dh_spa_guid = spa_guid(dev->l2ad_vdev->vdev_spa);
10340 l2dhdr->dh_vdev_guid = dev->l2ad_vdev->vdev_guid;
10341 l2dhdr->dh_log_entries = dev->l2ad_log_entries;
10342 l2dhdr->dh_evict = dev->l2ad_evict;
10343 l2dhdr->dh_start = dev->l2ad_start;
10344 l2dhdr->dh_end = dev->l2ad_end;
10345 l2dhdr->dh_lb_asize = zfs_refcount_count(&dev->l2ad_lb_asize);
10346 l2dhdr->dh_lb_count = zfs_refcount_count(&dev->l2ad_lb_count);
10347 l2dhdr->dh_flags = 0;
10348 l2dhdr->dh_trim_action_time = dev->l2ad_vdev->vdev_trim_action_time;
10349 l2dhdr->dh_trim_state = dev->l2ad_vdev->vdev_trim_state;
10350 if (dev->l2ad_first)
10351 l2dhdr->dh_flags |= L2ARC_DEV_HDR_EVICT_FIRST;
10353 abd = abd_get_from_buf(l2dhdr, l2dhdr_asize);
10355 err = zio_wait(zio_write_phys(NULL, dev->l2ad_vdev,
10356 VDEV_LABEL_START_SIZE, l2dhdr_asize, abd, ZIO_CHECKSUM_LABEL, NULL,
10357 NULL, ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_CANFAIL, B_FALSE));
10362 zfs_dbgmsg("L2ARC IO error (%d) while writing device header, "
10363 "vdev guid: %llu", err,
10364 (u_longlong_t)dev->l2ad_vdev->vdev_guid);
10369 * Commits a log block to the L2ARC device. This routine is invoked from
10370 * l2arc_write_buffers when the log block fills up.
10371 * This function allocates some memory to temporarily hold the serialized
10372 * buffer to be written. This is then released in l2arc_write_done.
10375 l2arc_log_blk_commit(l2arc_dev_t *dev, zio_t *pio, l2arc_write_callback_t *cb)
10377 l2arc_log_blk_phys_t *lb = &dev->l2ad_log_blk;
10378 l2arc_dev_hdr_phys_t *l2dhdr = dev->l2ad_dev_hdr;
10379 uint64_t psize, asize;
10381 l2arc_lb_abd_buf_t *abd_buf;
10382 uint8_t *tmpbuf = NULL;
10383 l2arc_lb_ptr_buf_t *lb_ptr_buf;
10385 VERIFY3S(dev->l2ad_log_ent_idx, ==, dev->l2ad_log_entries);
10387 abd_buf = zio_buf_alloc(sizeof (*abd_buf));
10388 abd_buf->abd = abd_get_from_buf(lb, sizeof (*lb));
10389 lb_ptr_buf = kmem_zalloc(sizeof (l2arc_lb_ptr_buf_t), KM_SLEEP);
10390 lb_ptr_buf->lb_ptr = kmem_zalloc(sizeof (l2arc_log_blkptr_t), KM_SLEEP);
10392 /* link the buffer into the block chain */
10393 lb->lb_prev_lbp = l2dhdr->dh_start_lbps[1];
10394 lb->lb_magic = L2ARC_LOG_BLK_MAGIC;
10397 * l2arc_log_blk_commit() may be called multiple times during a single
10398 * l2arc_write_buffers() call. Save the allocated abd buffers in a list
10399 * so we can free them in l2arc_write_done() later on.
10401 list_insert_tail(&cb->l2wcb_abd_list, abd_buf);
10403 /* try to compress the buffer */
10404 psize = zio_compress_data(ZIO_COMPRESS_LZ4,
10405 abd_buf->abd, (void **) &tmpbuf, sizeof (*lb), 0);
10407 /* a log block is never entirely zero */
10408 ASSERT(psize != 0);
10409 asize = vdev_psize_to_asize(dev->l2ad_vdev, psize);
10410 ASSERT(asize <= sizeof (*lb));
10413 * Update the start log block pointer in the device header to point
10414 * to the log block we're about to write.
10416 l2dhdr->dh_start_lbps[1] = l2dhdr->dh_start_lbps[0];
10417 l2dhdr->dh_start_lbps[0].lbp_daddr = dev->l2ad_hand;
10418 l2dhdr->dh_start_lbps[0].lbp_payload_asize =
10419 dev->l2ad_log_blk_payload_asize;
10420 l2dhdr->dh_start_lbps[0].lbp_payload_start =
10421 dev->l2ad_log_blk_payload_start;
10423 (&l2dhdr->dh_start_lbps[0])->lbp_prop, sizeof (*lb));
10425 (&l2dhdr->dh_start_lbps[0])->lbp_prop, asize);
10426 L2BLK_SET_CHECKSUM(
10427 (&l2dhdr->dh_start_lbps[0])->lbp_prop,
10428 ZIO_CHECKSUM_FLETCHER_4);
10429 if (asize < sizeof (*lb)) {
10430 /* compression succeeded */
10431 memset(tmpbuf + psize, 0, asize - psize);
10432 L2BLK_SET_COMPRESS(
10433 (&l2dhdr->dh_start_lbps[0])->lbp_prop,
10436 /* compression failed */
10437 memcpy(tmpbuf, lb, sizeof (*lb));
10438 L2BLK_SET_COMPRESS(
10439 (&l2dhdr->dh_start_lbps[0])->lbp_prop,
10443 /* checksum what we're about to write */
10444 fletcher_4_native(tmpbuf, asize, NULL,
10445 &l2dhdr->dh_start_lbps[0].lbp_cksum);
10447 abd_free(abd_buf->abd);
10449 /* perform the write itself */
10450 abd_buf->abd = abd_get_from_buf(tmpbuf, sizeof (*lb));
10451 abd_take_ownership_of_buf(abd_buf->abd, B_TRUE);
10452 wzio = zio_write_phys(pio, dev->l2ad_vdev, dev->l2ad_hand,
10453 asize, abd_buf->abd, ZIO_CHECKSUM_OFF, NULL, NULL,
10454 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_CANFAIL, B_FALSE);
10455 DTRACE_PROBE2(l2arc__write, vdev_t *, dev->l2ad_vdev, zio_t *, wzio);
10456 (void) zio_nowait(wzio);
10458 dev->l2ad_hand += asize;
10460 * Include the committed log block's pointer in the list of pointers
10461 * to log blocks present in the L2ARC device.
10463 memcpy(lb_ptr_buf->lb_ptr, &l2dhdr->dh_start_lbps[0],
10464 sizeof (l2arc_log_blkptr_t));
10465 mutex_enter(&dev->l2ad_mtx);
10466 list_insert_head(&dev->l2ad_lbptr_list, lb_ptr_buf);
10467 ARCSTAT_INCR(arcstat_l2_log_blk_asize, asize);
10468 ARCSTAT_BUMP(arcstat_l2_log_blk_count);
10469 zfs_refcount_add_many(&dev->l2ad_lb_asize, asize, lb_ptr_buf);
10470 zfs_refcount_add(&dev->l2ad_lb_count, lb_ptr_buf);
10471 mutex_exit(&dev->l2ad_mtx);
10472 vdev_space_update(dev->l2ad_vdev, asize, 0, 0);
10474 /* bump the kstats */
10475 ARCSTAT_INCR(arcstat_l2_write_bytes, asize);
10476 ARCSTAT_BUMP(arcstat_l2_log_blk_writes);
10477 ARCSTAT_F_AVG(arcstat_l2_log_blk_avg_asize, asize);
10478 ARCSTAT_F_AVG(arcstat_l2_data_to_meta_ratio,
10479 dev->l2ad_log_blk_payload_asize / asize);
10481 /* start a new log block */
10482 dev->l2ad_log_ent_idx = 0;
10483 dev->l2ad_log_blk_payload_asize = 0;
10484 dev->l2ad_log_blk_payload_start = 0;
10490 * Validates an L2ARC log block address to make sure that it can be read
10491 * from the provided L2ARC device.
10494 l2arc_log_blkptr_valid(l2arc_dev_t *dev, const l2arc_log_blkptr_t *lbp)
10496 /* L2BLK_GET_PSIZE returns aligned size for log blocks */
10497 uint64_t asize = L2BLK_GET_PSIZE((lbp)->lbp_prop);
10498 uint64_t end = lbp->lbp_daddr + asize - 1;
10499 uint64_t start = lbp->lbp_payload_start;
10500 boolean_t evicted = B_FALSE;
10503 * A log block is valid if all of the following conditions are true:
10504 * - it fits entirely (including its payload) between l2ad_start and
10506 * - it has a valid size
10507 * - neither the log block itself nor part of its payload was evicted
10508 * by l2arc_evict():
10510 * l2ad_hand l2ad_evict
10515 * l2ad_start ============================================ l2ad_end
10516 * --------------------------||||
10523 l2arc_range_check_overlap(start, end, dev->l2ad_hand) ||
10524 l2arc_range_check_overlap(start, end, dev->l2ad_evict) ||
10525 l2arc_range_check_overlap(dev->l2ad_hand, dev->l2ad_evict, start) ||
10526 l2arc_range_check_overlap(dev->l2ad_hand, dev->l2ad_evict, end);
10528 return (start >= dev->l2ad_start && end <= dev->l2ad_end &&
10529 asize > 0 && asize <= sizeof (l2arc_log_blk_phys_t) &&
10530 (!evicted || dev->l2ad_first));
10534 * Inserts ARC buffer header `hdr' into the current L2ARC log block on
10535 * the device. The buffer being inserted must be present in L2ARC.
10536 * Returns B_TRUE if the L2ARC log block is full and needs to be committed
10537 * to L2ARC, or B_FALSE if it still has room for more ARC buffers.
10540 l2arc_log_blk_insert(l2arc_dev_t *dev, const arc_buf_hdr_t *hdr)
10542 l2arc_log_blk_phys_t *lb = &dev->l2ad_log_blk;
10543 l2arc_log_ent_phys_t *le;
10545 if (dev->l2ad_log_entries == 0)
10548 int index = dev->l2ad_log_ent_idx++;
10550 ASSERT3S(index, <, dev->l2ad_log_entries);
10551 ASSERT(HDR_HAS_L2HDR(hdr));
10553 le = &lb->lb_entries[index];
10554 memset(le, 0, sizeof (*le));
10555 le->le_dva = hdr->b_dva;
10556 le->le_birth = hdr->b_birth;
10557 le->le_daddr = hdr->b_l2hdr.b_daddr;
10559 dev->l2ad_log_blk_payload_start = le->le_daddr;
10560 L2BLK_SET_LSIZE((le)->le_prop, HDR_GET_LSIZE(hdr));
10561 L2BLK_SET_PSIZE((le)->le_prop, HDR_GET_PSIZE(hdr));
10562 L2BLK_SET_COMPRESS((le)->le_prop, HDR_GET_COMPRESS(hdr));
10563 le->le_complevel = hdr->b_complevel;
10564 L2BLK_SET_TYPE((le)->le_prop, hdr->b_type);
10565 L2BLK_SET_PROTECTED((le)->le_prop, !!(HDR_PROTECTED(hdr)));
10566 L2BLK_SET_PREFETCH((le)->le_prop, !!(HDR_PREFETCH(hdr)));
10567 L2BLK_SET_STATE((le)->le_prop, hdr->b_l1hdr.b_state->arcs_state);
10569 dev->l2ad_log_blk_payload_asize += vdev_psize_to_asize(dev->l2ad_vdev,
10570 HDR_GET_PSIZE(hdr));
10572 return (dev->l2ad_log_ent_idx == dev->l2ad_log_entries);
10576 * Checks whether a given L2ARC device address sits in a time-sequential
10577 * range. The trick here is that the L2ARC is a rotary buffer, so we can't
10578 * just do a range comparison, we need to handle the situation in which the
10579 * range wraps around the end of the L2ARC device. Arguments:
10580 * bottom -- Lower end of the range to check (written to earlier).
10581 * top -- Upper end of the range to check (written to later).
10582 * check -- The address for which we want to determine if it sits in
10583 * between the top and bottom.
10585 * The 3-way conditional below represents the following cases:
10587 * bottom < top : Sequentially ordered case:
10588 * <check>--------+-------------------+
10589 * | (overlap here?) |
10591 * |---------------<bottom>============<top>--------------|
10593 * bottom > top: Looped-around case:
10594 * <check>--------+------------------+
10595 * | (overlap here?) |
10597 * |===============<top>---------------<bottom>===========|
10600 * +---------------+---------<check>
10602 * top == bottom : Just a single address comparison.
10605 l2arc_range_check_overlap(uint64_t bottom, uint64_t top, uint64_t check)
10608 return (bottom <= check && check <= top);
10609 else if (bottom > top)
10610 return (check <= top || bottom <= check);
10612 return (check == top);
10615 EXPORT_SYMBOL(arc_buf_size);
10616 EXPORT_SYMBOL(arc_write);
10617 EXPORT_SYMBOL(arc_read);
10618 EXPORT_SYMBOL(arc_buf_info);
10619 EXPORT_SYMBOL(arc_getbuf_func);
10620 EXPORT_SYMBOL(arc_add_prune_callback);
10621 EXPORT_SYMBOL(arc_remove_prune_callback);
10623 ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, min, param_set_arc_min,
10624 spl_param_get_u64, ZMOD_RW, "Minimum ARC size in bytes");
10626 ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, max, param_set_arc_max,
10627 spl_param_get_u64, ZMOD_RW, "Maximum ARC size in bytes");
10629 ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, meta_balance, UINT, ZMOD_RW,
10630 "Balance between metadata and data on ghost hits.");
10632 ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, grow_retry, param_set_arc_int,
10633 param_get_uint, ZMOD_RW, "Seconds before growing ARC size");
10635 ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, shrink_shift, param_set_arc_int,
10636 param_get_uint, ZMOD_RW, "log2(fraction of ARC to reclaim)");
10638 ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, pc_percent, UINT, ZMOD_RW,
10639 "Percent of pagecache to reclaim ARC to");
10641 ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, average_blocksize, UINT, ZMOD_RD,
10642 "Target average block size");
10644 ZFS_MODULE_PARAM(zfs, zfs_, compressed_arc_enabled, INT, ZMOD_RW,
10645 "Disable compressed ARC buffers");
10647 ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, min_prefetch_ms, param_set_arc_int,
10648 param_get_uint, ZMOD_RW, "Min life of prefetch block in ms");
10650 ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, min_prescient_prefetch_ms,
10651 param_set_arc_int, param_get_uint, ZMOD_RW,
10652 "Min life of prescient prefetched block in ms");
10654 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, write_max, U64, ZMOD_RW,
10655 "Max write bytes per interval");
10657 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, write_boost, U64, ZMOD_RW,
10658 "Extra write bytes during device warmup");
10660 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, headroom, U64, ZMOD_RW,
10661 "Number of max device writes to precache");
10663 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, headroom_boost, U64, ZMOD_RW,
10664 "Compressed l2arc_headroom multiplier");
10666 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, trim_ahead, U64, ZMOD_RW,
10667 "TRIM ahead L2ARC write size multiplier");
10669 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, feed_secs, U64, ZMOD_RW,
10670 "Seconds between L2ARC writing");
10672 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, feed_min_ms, U64, ZMOD_RW,
10673 "Min feed interval in milliseconds");
10675 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, noprefetch, INT, ZMOD_RW,
10676 "Skip caching prefetched buffers");
10678 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, feed_again, INT, ZMOD_RW,
10679 "Turbo L2ARC warmup");
10681 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, norw, INT, ZMOD_RW,
10682 "No reads during writes");
10684 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, meta_percent, UINT, ZMOD_RW,
10685 "Percent of ARC size allowed for L2ARC-only headers");
10687 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, rebuild_enabled, INT, ZMOD_RW,
10688 "Rebuild the L2ARC when importing a pool");
10690 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, rebuild_blocks_min_l2size, U64, ZMOD_RW,
10691 "Min size in bytes to write rebuild log blocks in L2ARC");
10693 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, mfuonly, INT, ZMOD_RW,
10694 "Cache only MFU data from ARC into L2ARC");
10696 ZFS_MODULE_PARAM(zfs_l2arc, l2arc_, exclude_special, INT, ZMOD_RW,
10697 "Exclude dbufs on special vdevs from being cached to L2ARC if set.");
10699 ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, lotsfree_percent, param_set_arc_int,
10700 param_get_uint, ZMOD_RW, "System free memory I/O throttle in bytes");
10702 ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, sys_free, param_set_arc_u64,
10703 spl_param_get_u64, ZMOD_RW, "System free memory target size in bytes");
10705 ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, dnode_limit, param_set_arc_u64,
10706 spl_param_get_u64, ZMOD_RW, "Minimum bytes of dnodes in ARC");
10708 ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, dnode_limit_percent,
10709 param_set_arc_int, param_get_uint, ZMOD_RW,
10710 "Percent of ARC meta buffers for dnodes");
10712 ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, dnode_reduce_percent, UINT, ZMOD_RW,
10713 "Percentage of excess dnodes to try to unpin");
10715 ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, eviction_pct, UINT, ZMOD_RW,
10716 "When full, ARC allocation waits for eviction of this % of alloc size");
10718 ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, evict_batch_limit, UINT, ZMOD_RW,
10719 "The number of headers to evict per sublist before moving to the next");
10721 ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, prune_task_threads, INT, ZMOD_RW,
10722 "Number of arc_prune threads");
projects / FreeBSD / FreeBSD.git / blob