4 * This file and its contents are supplied under the terms of the
5 * Common Development and Distribution License ("CDDL"), version 1.0.
6 * You may only use this file in accordance with the terms of version
9 * A full copy of the text of the CDDL should have accompanied this
10 * source. A copy of the CDDL is also available via the Internet at
11 * http://www.illumos.org/license/CDDL.
17 * Copyright (c) 2014, 2017 by Delphix. All rights reserved.
20 #include <sys/zfs_context.h>
22 #include <sys/spa_impl.h>
23 #include <sys/vdev_impl.h>
24 #include <sys/fs/zfs.h>
26 #include <sys/zio_checksum.h>
27 #include <sys/metaslab.h>
28 #include <sys/refcount.h>
30 #include <sys/vdev_indirect_mapping.h>
31 #include <sys/dmu_tx.h>
32 #include <sys/dsl_synctask.h>
38 * An indirect vdev corresponds to a vdev that has been removed. Since
39 * we cannot rewrite block pointers of snapshots, etc., we keep a
40 * mapping from old location on the removed device to the new location
41 * on another device in the pool and use this mapping whenever we need
42 * to access the DVA. Unfortunately, this mapping did not respect
43 * logical block boundaries when it was first created, and so a DVA on
44 * this indirect vdev may be "split" into multiple sections that each
45 * map to a different location. As a consequence, not all DVAs can be
46 * translated to an equivalent new DVA. Instead we must provide a
47 * "vdev_remap" operation that executes a callback on each contiguous
48 * segment of the new location. This function is used in multiple ways:
50 * - i/os to this vdev use the callback to determine where the
51 * data is now located, and issue child i/os for each segment's new
54 * - frees and claims to this vdev use the callback to free or claim
55 * each mapped segment. (Note that we don't actually need to claim
56 * log blocks on indirect vdevs, because we don't allocate to
57 * removing vdevs. However, zdb uses zio_claim() for its leak
62 * "Big theory statement" for how we mark blocks obsolete.
64 * When a block on an indirect vdev is freed or remapped, a section of
65 * that vdev's mapping may no longer be referenced (aka "obsolete"). We
66 * keep track of how much of each mapping entry is obsolete. When
67 * an entry becomes completely obsolete, we can remove it, thus reducing
68 * the memory used by the mapping. The complete picture of obsolescence
69 * is given by the following data structures, described below:
70 * - the entry-specific obsolete count
71 * - the vdev-specific obsolete spacemap
72 * - the pool-specific obsolete bpobj
74 * == On disk data structures used ==
76 * We track the obsolete space for the pool using several objects. Each
77 * of these objects is created on demand and freed when no longer
78 * needed, and is assumed to be empty if it does not exist.
79 * SPA_FEATURE_OBSOLETE_COUNTS includes the count of these objects.
81 * - Each vic_mapping_object (associated with an indirect vdev) can
82 * have a vimp_counts_object. This is an array of uint32_t's
83 * with the same number of entries as the vic_mapping_object. When
84 * the mapping is condensed, entries from the vic_obsolete_sm_object
85 * (see below) are folded into the counts. Therefore, each
86 * obsolete_counts entry tells us the number of bytes in the
87 * corresponding mapping entry that were not referenced when the
88 * mapping was last condensed.
90 * - Each indirect or removing vdev can have a vic_obsolete_sm_object.
91 * This is a space map containing an alloc entry for every DVA that
92 * has been obsoleted since the last time this indirect vdev was
93 * condensed. We use this object in order to improve performance
94 * when marking a DVA as obsolete. Instead of modifying an arbitrary
95 * offset of the vimp_counts_object, we only need to append an entry
96 * to the end of this object. When a DVA becomes obsolete, it is
97 * added to the obsolete space map. This happens when the DVA is
98 * freed, remapped and not referenced by a snapshot, or the last
99 * snapshot referencing it is destroyed.
101 * - Each dataset can have a ds_remap_deadlist object. This is a
102 * deadlist object containing all blocks that were remapped in this
103 * dataset but referenced in a previous snapshot. Blocks can *only*
104 * appear on this list if they were remapped (dsl_dataset_block_remapped);
105 * blocks that were killed in a head dataset are put on the normal
106 * ds_deadlist and marked obsolete when they are freed.
108 * - The pool can have a dp_obsolete_bpobj. This is a list of blocks
109 * in the pool that need to be marked obsolete. When a snapshot is
110 * destroyed, we move some of the ds_remap_deadlist to the obsolete
111 * bpobj (see dsl_destroy_snapshot_handle_remaps()). We then
112 * asynchronously process the obsolete bpobj, moving its entries to
113 * the specific vdevs' obsolete space maps.
115 * == Summary of how we mark blocks as obsolete ==
117 * - When freeing a block: if any DVA is on an indirect vdev, append to
118 * vic_obsolete_sm_object.
119 * - When remapping a block, add dva to ds_remap_deadlist (if prev snap
120 * references; otherwise append to vic_obsolete_sm_object).
121 * - When freeing a snapshot: move parts of ds_remap_deadlist to
122 * dp_obsolete_bpobj (same algorithm as ds_deadlist).
123 * - When syncing the spa: process dp_obsolete_bpobj, moving ranges to
124 * individual vdev's vic_obsolete_sm_object.
128 * "Big theory statement" for how we condense indirect vdevs.
130 * Condensing an indirect vdev's mapping is the process of determining
131 * the precise counts of obsolete space for each mapping entry (by
132 * integrating the obsolete spacemap into the obsolete counts) and
133 * writing out a new mapping that contains only referenced entries.
135 * We condense a vdev when we expect the mapping to shrink (see
136 * vdev_indirect_should_condense()), but only perform one condense at a
137 * time to limit the memory usage. In addition, we use a separate
138 * open-context thread (spa_condense_indirect_thread) to incrementally
139 * create the new mapping object in a way that minimizes the impact on
140 * the rest of the system.
142 * == Generating a new mapping ==
144 * To generate a new mapping, we follow these steps:
146 * 1. Save the old obsolete space map and create a new mapping object
147 * (see spa_condense_indirect_start_sync()). This initializes the
148 * spa_condensing_indirect_phys with the "previous obsolete space map",
149 * which is now read only. Newly obsolete DVAs will be added to a
150 * new (initially empty) obsolete space map, and will not be
151 * considered as part of this condense operation.
153 * 2. Construct in memory the precise counts of obsolete space for each
154 * mapping entry, by incorporating the obsolete space map into the
155 * counts. (See vdev_indirect_mapping_load_obsolete_{counts,spacemap}().)
157 * 3. Iterate through each mapping entry, writing to the new mapping any
158 * entries that are not completely obsolete (i.e. which don't have
159 * obsolete count == mapping length). (See
160 * spa_condense_indirect_generate_new_mapping().)
162 * 4. Destroy the old mapping object and switch over to the new one
163 * (spa_condense_indirect_complete_sync).
165 * == Restarting from failure ==
167 * To restart the condense when we import/open the pool, we must start
168 * at the 2nd step above: reconstruct the precise counts in memory,
169 * based on the space map + counts. Then in the 3rd step, we start
170 * iterating where we left off: at vimp_max_offset of the new mapping
174 boolean_t zfs_condense_indirect_vdevs_enable = B_TRUE;
177 * Condense if at least this percent of the bytes in the mapping is
178 * obsolete. With the default of 25%, the amount of space mapped
179 * will be reduced to 1% of its original size after at most 16
180 * condenses. Higher values will condense less often (causing less
181 * i/o); lower values will reduce the mapping size more quickly.
183 int zfs_indirect_condense_obsolete_pct = 25;
186 * Condense if the obsolete space map takes up more than this amount of
187 * space on disk (logically). This limits the amount of disk space
188 * consumed by the obsolete space map; the default of 1GB is small enough
189 * that we typically don't mind "wasting" it.
191 uint64_t zfs_condense_max_obsolete_bytes = 1024 * 1024 * 1024;
194 * Don't bother condensing if the mapping uses less than this amount of
195 * memory. The default of 128KB is considered a "trivial" amount of
196 * memory and not worth reducing.
198 uint64_t zfs_condense_min_mapping_bytes = 128 * 1024;
201 * This is used by the test suite so that it can ensure that certain
202 * actions happen while in the middle of a condense (which might otherwise
203 * complete too quickly). If used to reduce the performance impact of
204 * condensing in production, a maximum value of 1 should be sufficient.
206 int zfs_condense_indirect_commit_entry_delay_ticks = 0;
209 * If a split block contains more than this many segments, consider it too
210 * computationally expensive to check all (2^num_segments) possible
211 * combinations. Instead, try at most 2^_segments_max randomly-selected
214 * This is reasonable if only a few segment copies are damaged and the
215 * majority of segment copies are good. This allows all the segment copies to
216 * participate fairly in the reconstruction and prevents the repeated use of
219 int zfs_reconstruct_indirect_segments_max = 10;
222 * The indirect_child_t represents the vdev that we will read from, when we
223 * need to read all copies of the data (e.g. for scrub or reconstruction).
224 * For plain (non-mirror) top-level vdevs (i.e. is_vdev is not a mirror),
225 * ic_vdev is the same as is_vdev. However, for mirror top-level vdevs,
226 * ic_vdev is a child of the mirror.
228 typedef struct indirect_child {
234 * The indirect_split_t represents one mapped segment of an i/o to the
235 * indirect vdev. For non-split (contiguously-mapped) blocks, there will be
236 * only one indirect_split_t, with is_split_offset==0 and is_size==io_size.
237 * For split blocks, there will be several of these.
239 typedef struct indirect_split {
240 list_node_t is_node; /* link on iv_splits */
243 * is_split_offset is the offset into the i/o.
244 * This is the sum of the previous splits' is_size's.
246 uint64_t is_split_offset;
248 vdev_t *is_vdev; /* top-level vdev */
249 uint64_t is_target_offset; /* offset on is_vdev */
251 int is_children; /* number of entries in is_child[] */
254 * is_good_child is the child that we are currently using to
255 * attempt reconstruction.
259 indirect_child_t is_child[1]; /* variable-length */
263 * The indirect_vsd_t is associated with each i/o to the indirect vdev.
264 * It is the "Vdev-Specific Data" in the zio_t's io_vsd.
266 typedef struct indirect_vsd {
267 boolean_t iv_split_block;
268 boolean_t iv_reconstruct;
270 list_t iv_splits; /* list of indirect_split_t's */
274 vdev_indirect_map_free(zio_t *zio)
276 indirect_vsd_t *iv = zio->io_vsd;
278 indirect_split_t *is;
279 while ((is = list_head(&iv->iv_splits)) != NULL) {
280 for (int c = 0; c < is->is_children; c++) {
281 indirect_child_t *ic = &is->is_child[c];
282 if (ic->ic_data != NULL)
283 abd_free(ic->ic_data);
285 list_remove(&iv->iv_splits, is);
287 offsetof(indirect_split_t, is_child[is->is_children]));
289 kmem_free(iv, sizeof (*iv));
292 static const zio_vsd_ops_t vdev_indirect_vsd_ops = {
293 vdev_indirect_map_free,
294 zio_vsd_default_cksum_report
297 * Mark the given offset and size as being obsolete.
300 vdev_indirect_mark_obsolete(vdev_t *vd, uint64_t offset, uint64_t size)
302 spa_t *spa = vd->vdev_spa;
304 ASSERT3U(vd->vdev_indirect_config.vic_mapping_object, !=, 0);
305 ASSERT(vd->vdev_removing || vd->vdev_ops == &vdev_indirect_ops);
307 VERIFY(vdev_indirect_mapping_entry_for_offset(
308 vd->vdev_indirect_mapping, offset) != NULL);
310 if (spa_feature_is_enabled(spa, SPA_FEATURE_OBSOLETE_COUNTS)) {
311 mutex_enter(&vd->vdev_obsolete_lock);
312 range_tree_add(vd->vdev_obsolete_segments, offset, size);
313 mutex_exit(&vd->vdev_obsolete_lock);
314 vdev_dirty(vd, 0, NULL, spa_syncing_txg(spa));
319 * Mark the DVA vdev_id:offset:size as being obsolete in the given tx. This
320 * wrapper is provided because the DMU does not know about vdev_t's and
321 * cannot directly call vdev_indirect_mark_obsolete.
324 spa_vdev_indirect_mark_obsolete(spa_t *spa, uint64_t vdev_id, uint64_t offset,
325 uint64_t size, dmu_tx_t *tx)
327 vdev_t *vd = vdev_lookup_top(spa, vdev_id);
328 ASSERT(dmu_tx_is_syncing(tx));
330 /* The DMU can only remap indirect vdevs. */
331 ASSERT3P(vd->vdev_ops, ==, &vdev_indirect_ops);
332 vdev_indirect_mark_obsolete(vd, offset, size);
335 static spa_condensing_indirect_t *
336 spa_condensing_indirect_create(spa_t *spa)
338 spa_condensing_indirect_phys_t *scip =
339 &spa->spa_condensing_indirect_phys;
340 spa_condensing_indirect_t *sci = kmem_zalloc(sizeof (*sci), KM_SLEEP);
341 objset_t *mos = spa->spa_meta_objset;
343 for (int i = 0; i < TXG_SIZE; i++) {
344 list_create(&sci->sci_new_mapping_entries[i],
345 sizeof (vdev_indirect_mapping_entry_t),
346 offsetof(vdev_indirect_mapping_entry_t, vime_node));
349 sci->sci_new_mapping =
350 vdev_indirect_mapping_open(mos, scip->scip_next_mapping_object);
356 spa_condensing_indirect_destroy(spa_condensing_indirect_t *sci)
358 for (int i = 0; i < TXG_SIZE; i++)
359 list_destroy(&sci->sci_new_mapping_entries[i]);
361 if (sci->sci_new_mapping != NULL)
362 vdev_indirect_mapping_close(sci->sci_new_mapping);
364 kmem_free(sci, sizeof (*sci));
368 vdev_indirect_should_condense(vdev_t *vd)
370 vdev_indirect_mapping_t *vim = vd->vdev_indirect_mapping;
371 spa_t *spa = vd->vdev_spa;
373 ASSERT(dsl_pool_sync_context(spa->spa_dsl_pool));
375 if (!zfs_condense_indirect_vdevs_enable)
379 * We can only condense one indirect vdev at a time.
381 if (spa->spa_condensing_indirect != NULL)
384 if (spa_shutting_down(spa))
388 * The mapping object size must not change while we are
389 * condensing, so we can only condense indirect vdevs
390 * (not vdevs that are still in the middle of being removed).
392 if (vd->vdev_ops != &vdev_indirect_ops)
396 * If nothing new has been marked obsolete, there is no
397 * point in condensing.
399 if (vd->vdev_obsolete_sm == NULL) {
400 ASSERT0(vdev_obsolete_sm_object(vd));
404 ASSERT(vd->vdev_obsolete_sm != NULL);
406 ASSERT3U(vdev_obsolete_sm_object(vd), ==,
407 space_map_object(vd->vdev_obsolete_sm));
409 uint64_t bytes_mapped = vdev_indirect_mapping_bytes_mapped(vim);
410 uint64_t bytes_obsolete = space_map_allocated(vd->vdev_obsolete_sm);
411 uint64_t mapping_size = vdev_indirect_mapping_size(vim);
412 uint64_t obsolete_sm_size = space_map_length(vd->vdev_obsolete_sm);
414 ASSERT3U(bytes_obsolete, <=, bytes_mapped);
417 * If a high percentage of the bytes that are mapped have become
418 * obsolete, condense (unless the mapping is already small enough).
419 * This has a good chance of reducing the amount of memory used
422 if (bytes_obsolete * 100 / bytes_mapped >=
423 zfs_indirect_condense_obsolete_pct &&
424 mapping_size > zfs_condense_min_mapping_bytes) {
425 zfs_dbgmsg("should condense vdev %llu because obsolete "
426 "spacemap covers %d%% of %lluMB mapping",
427 (u_longlong_t)vd->vdev_id,
428 (int)(bytes_obsolete * 100 / bytes_mapped),
429 (u_longlong_t)bytes_mapped / 1024 / 1024);
434 * If the obsolete space map takes up too much space on disk,
435 * condense in order to free up this disk space.
437 if (obsolete_sm_size >= zfs_condense_max_obsolete_bytes) {
438 zfs_dbgmsg("should condense vdev %llu because obsolete sm "
439 "length %lluMB >= max size %lluMB",
440 (u_longlong_t)vd->vdev_id,
441 (u_longlong_t)obsolete_sm_size / 1024 / 1024,
442 (u_longlong_t)zfs_condense_max_obsolete_bytes /
451 * This sync task completes (finishes) a condense, deleting the old
452 * mapping and replacing it with the new one.
455 spa_condense_indirect_complete_sync(void *arg, dmu_tx_t *tx)
457 spa_condensing_indirect_t *sci = arg;
458 spa_t *spa = dmu_tx_pool(tx)->dp_spa;
459 spa_condensing_indirect_phys_t *scip =
460 &spa->spa_condensing_indirect_phys;
461 vdev_t *vd = vdev_lookup_top(spa, scip->scip_vdev);
462 vdev_indirect_config_t *vic = &vd->vdev_indirect_config;
463 objset_t *mos = spa->spa_meta_objset;
464 vdev_indirect_mapping_t *old_mapping = vd->vdev_indirect_mapping;
465 uint64_t old_count = vdev_indirect_mapping_num_entries(old_mapping);
467 vdev_indirect_mapping_num_entries(sci->sci_new_mapping);
469 ASSERT(dmu_tx_is_syncing(tx));
470 ASSERT3P(vd->vdev_ops, ==, &vdev_indirect_ops);
471 ASSERT3P(sci, ==, spa->spa_condensing_indirect);
472 for (int i = 0; i < TXG_SIZE; i++) {
473 ASSERT(list_is_empty(&sci->sci_new_mapping_entries[i]));
475 ASSERT(vic->vic_mapping_object != 0);
476 ASSERT3U(vd->vdev_id, ==, scip->scip_vdev);
477 ASSERT(scip->scip_next_mapping_object != 0);
478 ASSERT(scip->scip_prev_obsolete_sm_object != 0);
481 * Reset vdev_indirect_mapping to refer to the new object.
483 rw_enter(&vd->vdev_indirect_rwlock, RW_WRITER);
484 vdev_indirect_mapping_close(vd->vdev_indirect_mapping);
485 vd->vdev_indirect_mapping = sci->sci_new_mapping;
486 rw_exit(&vd->vdev_indirect_rwlock);
488 sci->sci_new_mapping = NULL;
489 vdev_indirect_mapping_free(mos, vic->vic_mapping_object, tx);
490 vic->vic_mapping_object = scip->scip_next_mapping_object;
491 scip->scip_next_mapping_object = 0;
493 space_map_free_obj(mos, scip->scip_prev_obsolete_sm_object, tx);
494 spa_feature_decr(spa, SPA_FEATURE_OBSOLETE_COUNTS, tx);
495 scip->scip_prev_obsolete_sm_object = 0;
499 VERIFY0(zap_remove(mos, DMU_POOL_DIRECTORY_OBJECT,
500 DMU_POOL_CONDENSING_INDIRECT, tx));
501 spa_condensing_indirect_destroy(spa->spa_condensing_indirect);
502 spa->spa_condensing_indirect = NULL;
504 zfs_dbgmsg("finished condense of vdev %llu in txg %llu: "
505 "new mapping object %llu has %llu entries "
506 "(was %llu entries)",
507 vd->vdev_id, dmu_tx_get_txg(tx), vic->vic_mapping_object,
508 new_count, old_count);
510 vdev_config_dirty(spa->spa_root_vdev);
514 * This sync task appends entries to the new mapping object.
517 spa_condense_indirect_commit_sync(void *arg, dmu_tx_t *tx)
519 spa_condensing_indirect_t *sci = arg;
520 uint64_t txg = dmu_tx_get_txg(tx);
521 spa_t *spa = dmu_tx_pool(tx)->dp_spa;
523 ASSERT(dmu_tx_is_syncing(tx));
524 ASSERT3P(sci, ==, spa->spa_condensing_indirect);
526 vdev_indirect_mapping_add_entries(sci->sci_new_mapping,
527 &sci->sci_new_mapping_entries[txg & TXG_MASK], tx);
528 ASSERT(list_is_empty(&sci->sci_new_mapping_entries[txg & TXG_MASK]));
532 * Open-context function to add one entry to the new mapping. The new
533 * entry will be remembered and written from syncing context.
536 spa_condense_indirect_commit_entry(spa_t *spa,
537 vdev_indirect_mapping_entry_phys_t *vimep, uint32_t count)
539 spa_condensing_indirect_t *sci = spa->spa_condensing_indirect;
541 ASSERT3U(count, <, DVA_GET_ASIZE(&vimep->vimep_dst));
543 dmu_tx_t *tx = dmu_tx_create_dd(spa_get_dsl(spa)->dp_mos_dir);
544 dmu_tx_hold_space(tx, sizeof (*vimep) + sizeof (count));
545 VERIFY0(dmu_tx_assign(tx, TXG_WAIT));
546 int txgoff = dmu_tx_get_txg(tx) & TXG_MASK;
549 * If we are the first entry committed this txg, kick off the sync
550 * task to write to the MOS on our behalf.
552 if (list_is_empty(&sci->sci_new_mapping_entries[txgoff])) {
553 dsl_sync_task_nowait(dmu_tx_pool(tx),
554 spa_condense_indirect_commit_sync, sci,
555 0, ZFS_SPACE_CHECK_NONE, tx);
558 vdev_indirect_mapping_entry_t *vime =
559 kmem_alloc(sizeof (*vime), KM_SLEEP);
560 vime->vime_mapping = *vimep;
561 vime->vime_obsolete_count = count;
562 list_insert_tail(&sci->sci_new_mapping_entries[txgoff], vime);
568 spa_condense_indirect_generate_new_mapping(vdev_t *vd,
569 uint32_t *obsolete_counts, uint64_t start_index, zthr_t *zthr)
571 spa_t *spa = vd->vdev_spa;
572 uint64_t mapi = start_index;
573 vdev_indirect_mapping_t *old_mapping = vd->vdev_indirect_mapping;
574 uint64_t old_num_entries =
575 vdev_indirect_mapping_num_entries(old_mapping);
577 ASSERT3P(vd->vdev_ops, ==, &vdev_indirect_ops);
578 ASSERT3U(vd->vdev_id, ==, spa->spa_condensing_indirect_phys.scip_vdev);
580 zfs_dbgmsg("starting condense of vdev %llu from index %llu",
581 (u_longlong_t)vd->vdev_id,
584 while (mapi < old_num_entries) {
586 if (zthr_iscancelled(zthr)) {
587 zfs_dbgmsg("pausing condense of vdev %llu "
588 "at index %llu", (u_longlong_t)vd->vdev_id,
593 vdev_indirect_mapping_entry_phys_t *entry =
594 &old_mapping->vim_entries[mapi];
595 uint64_t entry_size = DVA_GET_ASIZE(&entry->vimep_dst);
596 ASSERT3U(obsolete_counts[mapi], <=, entry_size);
597 if (obsolete_counts[mapi] < entry_size) {
598 spa_condense_indirect_commit_entry(spa, entry,
599 obsolete_counts[mapi]);
602 * This delay may be requested for testing, debugging,
603 * or performance reasons.
605 delay(zfs_condense_indirect_commit_entry_delay_ticks);
614 spa_condense_indirect_thread_check(void *arg, zthr_t *zthr)
618 return (spa->spa_condensing_indirect != NULL);
623 spa_condense_indirect_thread(void *arg, zthr_t *zthr)
628 ASSERT3P(spa->spa_condensing_indirect, !=, NULL);
629 spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);
630 vd = vdev_lookup_top(spa, spa->spa_condensing_indirect_phys.scip_vdev);
631 ASSERT3P(vd, !=, NULL);
632 spa_config_exit(spa, SCL_VDEV, FTAG);
634 spa_condensing_indirect_t *sci = spa->spa_condensing_indirect;
635 spa_condensing_indirect_phys_t *scip =
636 &spa->spa_condensing_indirect_phys;
638 uint64_t start_index;
639 vdev_indirect_mapping_t *old_mapping = vd->vdev_indirect_mapping;
640 space_map_t *prev_obsolete_sm = NULL;
642 ASSERT3U(vd->vdev_id, ==, scip->scip_vdev);
643 ASSERT(scip->scip_next_mapping_object != 0);
644 ASSERT(scip->scip_prev_obsolete_sm_object != 0);
645 ASSERT3P(vd->vdev_ops, ==, &vdev_indirect_ops);
647 for (int i = 0; i < TXG_SIZE; i++) {
649 * The list must start out empty in order for the
650 * _commit_sync() sync task to be properly registered
651 * on the first call to _commit_entry(); so it's wise
652 * to double check and ensure we actually are starting
655 ASSERT(list_is_empty(&sci->sci_new_mapping_entries[i]));
658 VERIFY0(space_map_open(&prev_obsolete_sm, spa->spa_meta_objset,
659 scip->scip_prev_obsolete_sm_object, 0, vd->vdev_asize, 0));
660 space_map_update(prev_obsolete_sm);
661 counts = vdev_indirect_mapping_load_obsolete_counts(old_mapping);
662 if (prev_obsolete_sm != NULL) {
663 vdev_indirect_mapping_load_obsolete_spacemap(old_mapping,
664 counts, prev_obsolete_sm);
666 space_map_close(prev_obsolete_sm);
669 * Generate new mapping. Determine what index to continue from
670 * based on the max offset that we've already written in the
673 uint64_t max_offset =
674 vdev_indirect_mapping_max_offset(sci->sci_new_mapping);
675 if (max_offset == 0) {
676 /* We haven't written anything to the new mapping yet. */
680 * Pick up from where we left off. _entry_for_offset()
681 * returns a pointer into the vim_entries array. If
682 * max_offset is greater than any of the mappings
683 * contained in the table NULL will be returned and
684 * that indicates we've exhausted our iteration of the
688 vdev_indirect_mapping_entry_phys_t *entry =
689 vdev_indirect_mapping_entry_for_offset_or_next(old_mapping,
694 * We've already written the whole new mapping.
695 * This special value will cause us to skip the
696 * generate_new_mapping step and just do the sync
697 * task to complete the condense.
699 start_index = UINT64_MAX;
701 start_index = entry - old_mapping->vim_entries;
702 ASSERT3U(start_index, <,
703 vdev_indirect_mapping_num_entries(old_mapping));
707 spa_condense_indirect_generate_new_mapping(vd, counts,
710 vdev_indirect_mapping_free_obsolete_counts(old_mapping, counts);
713 * If the zthr has received a cancellation signal while running
714 * in generate_new_mapping() or at any point after that, then bail
715 * early. We don't want to complete the condense if the spa is
718 if (zthr_iscancelled(zthr))
721 VERIFY0(dsl_sync_task(spa_name(spa), NULL,
722 spa_condense_indirect_complete_sync, sci, 0,
723 ZFS_SPACE_CHECK_EXTRA_RESERVED));
730 * Sync task to begin the condensing process.
733 spa_condense_indirect_start_sync(vdev_t *vd, dmu_tx_t *tx)
735 spa_t *spa = vd->vdev_spa;
736 spa_condensing_indirect_phys_t *scip =
737 &spa->spa_condensing_indirect_phys;
739 ASSERT0(scip->scip_next_mapping_object);
740 ASSERT0(scip->scip_prev_obsolete_sm_object);
741 ASSERT0(scip->scip_vdev);
742 ASSERT(dmu_tx_is_syncing(tx));
743 ASSERT3P(vd->vdev_ops, ==, &vdev_indirect_ops);
744 ASSERT(spa_feature_is_active(spa, SPA_FEATURE_OBSOLETE_COUNTS));
745 ASSERT(vdev_indirect_mapping_num_entries(vd->vdev_indirect_mapping));
747 uint64_t obsolete_sm_obj = vdev_obsolete_sm_object(vd);
748 ASSERT(obsolete_sm_obj != 0);
750 scip->scip_vdev = vd->vdev_id;
751 scip->scip_next_mapping_object =
752 vdev_indirect_mapping_alloc(spa->spa_meta_objset, tx);
754 scip->scip_prev_obsolete_sm_object = obsolete_sm_obj;
757 * We don't need to allocate a new space map object, since
758 * vdev_indirect_sync_obsolete will allocate one when needed.
760 space_map_close(vd->vdev_obsolete_sm);
761 vd->vdev_obsolete_sm = NULL;
762 VERIFY0(zap_remove(spa->spa_meta_objset, vd->vdev_top_zap,
763 VDEV_TOP_ZAP_INDIRECT_OBSOLETE_SM, tx));
765 VERIFY0(zap_add(spa->spa_dsl_pool->dp_meta_objset,
766 DMU_POOL_DIRECTORY_OBJECT,
767 DMU_POOL_CONDENSING_INDIRECT, sizeof (uint64_t),
768 sizeof (*scip) / sizeof (uint64_t), scip, tx));
770 ASSERT3P(spa->spa_condensing_indirect, ==, NULL);
771 spa->spa_condensing_indirect = spa_condensing_indirect_create(spa);
773 zfs_dbgmsg("starting condense of vdev %llu in txg %llu: "
775 vd->vdev_id, dmu_tx_get_txg(tx),
776 (u_longlong_t)scip->scip_prev_obsolete_sm_object,
777 (u_longlong_t)scip->scip_next_mapping_object);
779 zthr_wakeup(spa->spa_condense_zthr);
783 * Sync to the given vdev's obsolete space map any segments that are no longer
784 * referenced as of the given txg.
786 * If the obsolete space map doesn't exist yet, create and open it.
789 vdev_indirect_sync_obsolete(vdev_t *vd, dmu_tx_t *tx)
791 spa_t *spa = vd->vdev_spa;
792 vdev_indirect_config_t *vic = &vd->vdev_indirect_config;
794 ASSERT3U(vic->vic_mapping_object, !=, 0);
795 ASSERT(range_tree_space(vd->vdev_obsolete_segments) > 0);
796 ASSERT(vd->vdev_removing || vd->vdev_ops == &vdev_indirect_ops);
797 ASSERT(spa_feature_is_enabled(spa, SPA_FEATURE_OBSOLETE_COUNTS));
799 if (vdev_obsolete_sm_object(vd) == 0) {
800 uint64_t obsolete_sm_object =
801 space_map_alloc(spa->spa_meta_objset,
802 vdev_standard_sm_blksz, tx);
804 ASSERT(vd->vdev_top_zap != 0);
805 VERIFY0(zap_add(vd->vdev_spa->spa_meta_objset, vd->vdev_top_zap,
806 VDEV_TOP_ZAP_INDIRECT_OBSOLETE_SM,
807 sizeof (obsolete_sm_object), 1, &obsolete_sm_object, tx));
808 ASSERT3U(vdev_obsolete_sm_object(vd), !=, 0);
810 spa_feature_incr(spa, SPA_FEATURE_OBSOLETE_COUNTS, tx);
811 VERIFY0(space_map_open(&vd->vdev_obsolete_sm,
812 spa->spa_meta_objset, obsolete_sm_object,
813 0, vd->vdev_asize, 0));
814 space_map_update(vd->vdev_obsolete_sm);
817 ASSERT(vd->vdev_obsolete_sm != NULL);
818 ASSERT3U(vdev_obsolete_sm_object(vd), ==,
819 space_map_object(vd->vdev_obsolete_sm));
821 space_map_write(vd->vdev_obsolete_sm,
822 vd->vdev_obsolete_segments, SM_ALLOC, SM_NO_VDEVID, tx);
823 space_map_update(vd->vdev_obsolete_sm);
824 range_tree_vacate(vd->vdev_obsolete_segments, NULL, NULL);
828 spa_condense_init(spa_t *spa)
830 int error = zap_lookup(spa->spa_meta_objset,
831 DMU_POOL_DIRECTORY_OBJECT,
832 DMU_POOL_CONDENSING_INDIRECT, sizeof (uint64_t),
833 sizeof (spa->spa_condensing_indirect_phys) / sizeof (uint64_t),
834 &spa->spa_condensing_indirect_phys);
836 if (spa_writeable(spa)) {
837 spa->spa_condensing_indirect =
838 spa_condensing_indirect_create(spa);
841 } else if (error == ENOENT) {
849 spa_condense_fini(spa_t *spa)
851 if (spa->spa_condensing_indirect != NULL) {
852 spa_condensing_indirect_destroy(spa->spa_condensing_indirect);
853 spa->spa_condensing_indirect = NULL;
858 spa_start_indirect_condensing_thread(spa_t *spa)
860 ASSERT3P(spa->spa_condense_zthr, ==, NULL);
861 spa->spa_condense_zthr = zthr_create(spa_condense_indirect_thread_check,
862 spa_condense_indirect_thread, spa);
866 * Gets the obsolete spacemap object from the vdev's ZAP.
867 * Returns the spacemap object, or 0 if it wasn't in the ZAP or the ZAP doesn't
871 vdev_obsolete_sm_object(vdev_t *vd)
873 ASSERT0(spa_config_held(vd->vdev_spa, SCL_ALL, RW_WRITER));
874 if (vd->vdev_top_zap == 0) {
879 int err = zap_lookup(vd->vdev_spa->spa_meta_objset, vd->vdev_top_zap,
880 VDEV_TOP_ZAP_INDIRECT_OBSOLETE_SM, sizeof (sm_obj), 1, &sm_obj);
882 ASSERT(err == 0 || err == ENOENT);
888 vdev_obsolete_counts_are_precise(vdev_t *vd)
890 ASSERT0(spa_config_held(vd->vdev_spa, SCL_ALL, RW_WRITER));
891 if (vd->vdev_top_zap == 0) {
896 int err = zap_lookup(vd->vdev_spa->spa_meta_objset, vd->vdev_top_zap,
897 VDEV_TOP_ZAP_OBSOLETE_COUNTS_ARE_PRECISE, sizeof (val), 1, &val);
899 ASSERT(err == 0 || err == ENOENT);
906 vdev_indirect_close(vdev_t *vd)
912 vdev_indirect_open(vdev_t *vd, uint64_t *psize, uint64_t *max_psize,
913 uint64_t *logical_ashift, uint64_t *physical_ashift)
915 *psize = *max_psize = vd->vdev_asize +
916 VDEV_LABEL_START_SIZE + VDEV_LABEL_END_SIZE;
917 *logical_ashift = vd->vdev_ashift;
918 *physical_ashift = vd->vdev_physical_ashift;
922 typedef struct remap_segment {
926 uint64_t rs_split_offset;
931 rs_alloc(vdev_t *vd, uint64_t offset, uint64_t asize, uint64_t split_offset)
933 remap_segment_t *rs = kmem_alloc(sizeof (remap_segment_t), KM_SLEEP);
935 rs->rs_offset = offset;
936 rs->rs_asize = asize;
937 rs->rs_split_offset = split_offset;
942 * Given an indirect vdev and an extent on that vdev, it duplicates the
943 * physical entries of the indirect mapping that correspond to the extent
944 * to a new array and returns a pointer to it. In addition, copied_entries
945 * is populated with the number of mapping entries that were duplicated.
947 * Note that the function assumes that the caller holds vdev_indirect_rwlock.
948 * This ensures that the mapping won't change due to condensing as we
949 * copy over its contents.
951 * Finally, since we are doing an allocation, it is up to the caller to
952 * free the array allocated in this function.
954 vdev_indirect_mapping_entry_phys_t *
955 vdev_indirect_mapping_duplicate_adjacent_entries(vdev_t *vd, uint64_t offset,
956 uint64_t asize, uint64_t *copied_entries)
958 vdev_indirect_mapping_entry_phys_t *duplicate_mappings = NULL;
959 vdev_indirect_mapping_t *vim = vd->vdev_indirect_mapping;
960 uint64_t entries = 0;
962 ASSERT(RW_READ_HELD(&vd->vdev_indirect_rwlock));
964 vdev_indirect_mapping_entry_phys_t *first_mapping =
965 vdev_indirect_mapping_entry_for_offset(vim, offset);
966 ASSERT3P(first_mapping, !=, NULL);
968 vdev_indirect_mapping_entry_phys_t *m = first_mapping;
970 uint64_t size = DVA_GET_ASIZE(&m->vimep_dst);
972 ASSERT3U(offset, >=, DVA_MAPPING_GET_SRC_OFFSET(m));
973 ASSERT3U(offset, <, DVA_MAPPING_GET_SRC_OFFSET(m) + size);
975 uint64_t inner_offset = offset - DVA_MAPPING_GET_SRC_OFFSET(m);
976 uint64_t inner_size = MIN(asize, size - inner_offset);
978 offset += inner_size;
984 size_t copy_length = entries * sizeof (*first_mapping);
985 duplicate_mappings = kmem_alloc(copy_length, KM_SLEEP);
986 bcopy(first_mapping, duplicate_mappings, copy_length);
987 *copied_entries = entries;
989 return (duplicate_mappings);
993 * Goes through the relevant indirect mappings until it hits a concrete vdev
994 * and issues the callback. On the way to the concrete vdev, if any other
995 * indirect vdevs are encountered, then the callback will also be called on
996 * each of those indirect vdevs. For example, if the segment is mapped to
997 * segment A on indirect vdev 1, and then segment A on indirect vdev 1 is
998 * mapped to segment B on concrete vdev 2, then the callback will be called on
999 * both vdev 1 and vdev 2.
1001 * While the callback passed to vdev_indirect_remap() is called on every vdev
1002 * the function encounters, certain callbacks only care about concrete vdevs.
1003 * These types of callbacks should return immediately and explicitly when they
1004 * are called on an indirect vdev.
1006 * Because there is a possibility that a DVA section in the indirect device
1007 * has been split into multiple sections in our mapping, we keep track
1008 * of the relevant contiguous segments of the new location (remap_segment_t)
1009 * in a stack. This way we can call the callback for each of the new sections
1010 * created by a single section of the indirect device. Note though, that in
1011 * this scenario the callbacks in each split block won't occur in-order in
1012 * terms of offset, so callers should not make any assumptions about that.
1014 * For callbacks that don't handle split blocks and immediately return when
1015 * they encounter them (as is the case for remap_blkptr_cb), the caller can
1016 * assume that its callback will be applied from the first indirect vdev
1017 * encountered to the last one and then the concrete vdev, in that order.
1020 vdev_indirect_remap(vdev_t *vd, uint64_t offset, uint64_t asize,
1021 void (*func)(uint64_t, vdev_t *, uint64_t, uint64_t, void *), void *arg)
1024 spa_t *spa = vd->vdev_spa;
1026 list_create(&stack, sizeof (remap_segment_t),
1027 offsetof(remap_segment_t, rs_node));
1029 for (remap_segment_t *rs = rs_alloc(vd, offset, asize, 0);
1030 rs != NULL; rs = list_remove_head(&stack)) {
1031 vdev_t *v = rs->rs_vd;
1032 uint64_t num_entries = 0;
1034 ASSERT(spa_config_held(spa, SCL_ALL, RW_READER) != 0);
1035 ASSERT(rs->rs_asize > 0);
1038 * Note: As this function can be called from open context
1039 * (e.g. zio_read()), we need the following rwlock to
1040 * prevent the mapping from being changed by condensing.
1042 * So we grab the lock and we make a copy of the entries
1043 * that are relevant to the extent that we are working on.
1044 * Once that is done, we drop the lock and iterate over
1045 * our copy of the mapping. Once we are done with the with
1046 * the remap segment and we free it, we also free our copy
1047 * of the indirect mapping entries that are relevant to it.
1049 * This way we don't need to wait until the function is
1050 * finished with a segment, to condense it. In addition, we
1051 * don't need a recursive rwlock for the case that a call to
1052 * vdev_indirect_remap() needs to call itself (through the
1053 * codepath of its callback) for the same vdev in the middle
1056 rw_enter(&v->vdev_indirect_rwlock, RW_READER);
1057 vdev_indirect_mapping_t *vim = v->vdev_indirect_mapping;
1058 ASSERT3P(vim, !=, NULL);
1060 vdev_indirect_mapping_entry_phys_t *mapping =
1061 vdev_indirect_mapping_duplicate_adjacent_entries(v,
1062 rs->rs_offset, rs->rs_asize, &num_entries);
1063 ASSERT3P(mapping, !=, NULL);
1064 ASSERT3U(num_entries, >, 0);
1065 rw_exit(&v->vdev_indirect_rwlock);
1067 for (uint64_t i = 0; i < num_entries; i++) {
1069 * Note: the vdev_indirect_mapping can not change
1070 * while we are running. It only changes while the
1071 * removal is in progress, and then only from syncing
1072 * context. While a removal is in progress, this
1073 * function is only called for frees, which also only
1074 * happen from syncing context.
1076 vdev_indirect_mapping_entry_phys_t *m = &mapping[i];
1078 ASSERT3P(m, !=, NULL);
1079 ASSERT3U(rs->rs_asize, >, 0);
1081 uint64_t size = DVA_GET_ASIZE(&m->vimep_dst);
1082 uint64_t dst_offset = DVA_GET_OFFSET(&m->vimep_dst);
1083 uint64_t dst_vdev = DVA_GET_VDEV(&m->vimep_dst);
1085 ASSERT3U(rs->rs_offset, >=,
1086 DVA_MAPPING_GET_SRC_OFFSET(m));
1087 ASSERT3U(rs->rs_offset, <,
1088 DVA_MAPPING_GET_SRC_OFFSET(m) + size);
1089 ASSERT3U(dst_vdev, !=, v->vdev_id);
1091 uint64_t inner_offset = rs->rs_offset -
1092 DVA_MAPPING_GET_SRC_OFFSET(m);
1093 uint64_t inner_size =
1094 MIN(rs->rs_asize, size - inner_offset);
1096 vdev_t *dst_v = vdev_lookup_top(spa, dst_vdev);
1097 ASSERT3P(dst_v, !=, NULL);
1099 if (dst_v->vdev_ops == &vdev_indirect_ops) {
1100 list_insert_head(&stack,
1101 rs_alloc(dst_v, dst_offset + inner_offset,
1102 inner_size, rs->rs_split_offset));
1106 if ((zfs_flags & ZFS_DEBUG_INDIRECT_REMAP) &&
1107 IS_P2ALIGNED(inner_size, 2 * SPA_MINBLOCKSIZE)) {
1109 * Note: This clause exists only solely for
1110 * testing purposes. We use it to ensure that
1111 * split blocks work and that the callbacks
1112 * using them yield the same result if issued
1115 uint64_t inner_half = inner_size / 2;
1117 func(rs->rs_split_offset + inner_half, dst_v,
1118 dst_offset + inner_offset + inner_half,
1121 func(rs->rs_split_offset, dst_v,
1122 dst_offset + inner_offset,
1125 func(rs->rs_split_offset, dst_v,
1126 dst_offset + inner_offset,
1130 rs->rs_offset += inner_size;
1131 rs->rs_asize -= inner_size;
1132 rs->rs_split_offset += inner_size;
1134 VERIFY0(rs->rs_asize);
1136 kmem_free(mapping, num_entries * sizeof (*mapping));
1137 kmem_free(rs, sizeof (remap_segment_t));
1139 list_destroy(&stack);
1143 vdev_indirect_child_io_done(zio_t *zio)
1145 zio_t *pio = zio->io_private;
1147 mutex_enter(&pio->io_lock);
1148 pio->io_error = zio_worst_error(pio->io_error, zio->io_error);
1149 mutex_exit(&pio->io_lock);
1151 abd_put(zio->io_abd);
1155 * This is a callback for vdev_indirect_remap() which allocates an
1156 * indirect_split_t for each split segment and adds it to iv_splits.
1159 vdev_indirect_gather_splits(uint64_t split_offset, vdev_t *vd, uint64_t offset,
1160 uint64_t size, void *arg)
1163 indirect_vsd_t *iv = zio->io_vsd;
1165 ASSERT3P(vd, !=, NULL);
1167 if (vd->vdev_ops == &vdev_indirect_ops)
1171 if (vd->vdev_ops == &vdev_mirror_ops)
1172 n = vd->vdev_children;
1174 indirect_split_t *is =
1175 kmem_zalloc(offsetof(indirect_split_t, is_child[n]), KM_SLEEP);
1177 is->is_children = n;
1179 is->is_split_offset = split_offset;
1180 is->is_target_offset = offset;
1184 * Note that we only consider multiple copies of the data for
1185 * *mirror* vdevs. We don't for "replacing" or "spare" vdevs, even
1186 * though they use the same ops as mirror, because there's only one
1187 * "good" copy under the replacing/spare.
1189 if (vd->vdev_ops == &vdev_mirror_ops) {
1190 for (int i = 0; i < n; i++) {
1191 is->is_child[i].ic_vdev = vd->vdev_child[i];
1194 is->is_child[0].ic_vdev = vd;
1197 list_insert_tail(&iv->iv_splits, is);
1201 vdev_indirect_read_split_done(zio_t *zio)
1203 indirect_child_t *ic = zio->io_private;
1205 if (zio->io_error != 0) {
1207 * Clear ic_data to indicate that we do not have data for this
1210 abd_free(ic->ic_data);
1216 * Issue reads for all copies (mirror children) of all splits.
1219 vdev_indirect_read_all(zio_t *zio)
1221 indirect_vsd_t *iv = zio->io_vsd;
1223 for (indirect_split_t *is = list_head(&iv->iv_splits);
1224 is != NULL; is = list_next(&iv->iv_splits, is)) {
1225 for (int i = 0; i < is->is_children; i++) {
1226 indirect_child_t *ic = &is->is_child[i];
1228 if (!vdev_readable(ic->ic_vdev))
1232 * Note, we may read from a child whose DTL
1233 * indicates that the data may not be present here.
1234 * While this might result in a few i/os that will
1235 * likely return incorrect data, it simplifies the
1236 * code since we can treat scrub and resilver
1237 * identically. (The incorrect data will be
1238 * detected and ignored when we verify the
1242 ic->ic_data = abd_alloc_sametype(zio->io_abd,
1245 zio_nowait(zio_vdev_child_io(zio, NULL,
1246 ic->ic_vdev, is->is_target_offset, ic->ic_data,
1247 is->is_size, zio->io_type, zio->io_priority, 0,
1248 vdev_indirect_read_split_done, ic));
1251 iv->iv_reconstruct = B_TRUE;
1255 vdev_indirect_io_start(zio_t *zio)
1257 spa_t *spa = zio->io_spa;
1258 indirect_vsd_t *iv = kmem_zalloc(sizeof (*iv), KM_SLEEP);
1259 list_create(&iv->iv_splits,
1260 sizeof (indirect_split_t), offsetof(indirect_split_t, is_node));
1263 zio->io_vsd_ops = &vdev_indirect_vsd_ops;
1265 ASSERT(spa_config_held(spa, SCL_ALL, RW_READER) != 0);
1266 if (zio->io_type != ZIO_TYPE_READ) {
1267 ASSERT3U(zio->io_type, ==, ZIO_TYPE_WRITE);
1269 * Note: this code can handle other kinds of writes,
1270 * but we don't expect them.
1272 ASSERT((zio->io_flags & (ZIO_FLAG_SELF_HEAL |
1273 ZIO_FLAG_RESILVER | ZIO_FLAG_INDUCE_DAMAGE)) != 0);
1276 vdev_indirect_remap(zio->io_vd, zio->io_offset, zio->io_size,
1277 vdev_indirect_gather_splits, zio);
1279 indirect_split_t *first = list_head(&iv->iv_splits);
1280 if (first->is_size == zio->io_size) {
1282 * This is not a split block; we are pointing to the entire
1283 * data, which will checksum the same as the original data.
1284 * Pass the BP down so that the child i/o can verify the
1285 * checksum, and try a different location if available
1286 * (e.g. on a mirror).
1288 * While this special case could be handled the same as the
1289 * general (split block) case, doing it this way ensures
1290 * that the vast majority of blocks on indirect vdevs
1291 * (which are not split) are handled identically to blocks
1292 * on non-indirect vdevs. This allows us to be less strict
1293 * about performance in the general (but rare) case.
1295 ASSERT0(first->is_split_offset);
1296 ASSERT3P(list_next(&iv->iv_splits, first), ==, NULL);
1297 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
1298 first->is_vdev, first->is_target_offset,
1299 abd_get_offset(zio->io_abd, 0),
1300 zio->io_size, zio->io_type, zio->io_priority, 0,
1301 vdev_indirect_child_io_done, zio));
1303 iv->iv_split_block = B_TRUE;
1304 if (zio->io_flags & (ZIO_FLAG_SCRUB | ZIO_FLAG_RESILVER)) {
1306 * Read all copies. Note that for simplicity,
1307 * we don't bother consulting the DTL in the
1310 vdev_indirect_read_all(zio);
1313 * Read one copy of each split segment, from the
1314 * top-level vdev. Since we don't know the
1315 * checksum of each split individually, the child
1316 * zio can't ensure that we get the right data.
1317 * E.g. if it's a mirror, it will just read from a
1318 * random (healthy) leaf vdev. We have to verify
1319 * the checksum in vdev_indirect_io_done().
1321 for (indirect_split_t *is = list_head(&iv->iv_splits);
1322 is != NULL; is = list_next(&iv->iv_splits, is)) {
1323 zio_nowait(zio_vdev_child_io(zio, NULL,
1324 is->is_vdev, is->is_target_offset,
1325 abd_get_offset(zio->io_abd,
1326 is->is_split_offset),
1327 is->is_size, zio->io_type,
1328 zio->io_priority, 0,
1329 vdev_indirect_child_io_done, zio));
1338 * Report a checksum error for a child.
1341 vdev_indirect_checksum_error(zio_t *zio,
1342 indirect_split_t *is, indirect_child_t *ic)
1344 vdev_t *vd = ic->ic_vdev;
1346 if (zio->io_flags & ZIO_FLAG_SPECULATIVE)
1349 mutex_enter(&vd->vdev_stat_lock);
1350 vd->vdev_stat.vs_checksum_errors++;
1351 mutex_exit(&vd->vdev_stat_lock);
1353 zio_bad_cksum_t zbc = { 0 };
1354 void *bad_buf = abd_borrow_buf_copy(ic->ic_data, is->is_size);
1355 abd_t *good_abd = is->is_child[is->is_good_child].ic_data;
1356 void *good_buf = abd_borrow_buf_copy(good_abd, is->is_size);
1357 zfs_ereport_post_checksum(zio->io_spa, vd, zio,
1358 is->is_target_offset, is->is_size, good_buf, bad_buf, &zbc);
1359 abd_return_buf(ic->ic_data, bad_buf, is->is_size);
1360 abd_return_buf(good_abd, good_buf, is->is_size);
1364 * Issue repair i/os for any incorrect copies. We do this by comparing
1365 * each split segment's correct data (is_good_child's ic_data) with each
1366 * other copy of the data. If they differ, then we overwrite the bad data
1367 * with the good copy. Note that we do this without regard for the DTL's,
1368 * which simplifies this code and also issues the optimal number of writes
1369 * (based on which copies actually read bad data, as opposed to which we
1370 * think might be wrong). For the same reason, we always use
1371 * ZIO_FLAG_SELF_HEAL, to bypass the DTL check in zio_vdev_io_start().
1374 vdev_indirect_repair(zio_t *zio)
1376 indirect_vsd_t *iv = zio->io_vsd;
1378 enum zio_flag flags = ZIO_FLAG_IO_REPAIR;
1380 if (!(zio->io_flags & (ZIO_FLAG_SCRUB | ZIO_FLAG_RESILVER)))
1381 flags |= ZIO_FLAG_SELF_HEAL;
1383 if (!spa_writeable(zio->io_spa))
1386 for (indirect_split_t *is = list_head(&iv->iv_splits);
1387 is != NULL; is = list_next(&iv->iv_splits, is)) {
1388 indirect_child_t *good_child = &is->is_child[is->is_good_child];
1390 for (int c = 0; c < is->is_children; c++) {
1391 indirect_child_t *ic = &is->is_child[c];
1392 if (ic == good_child)
1394 if (ic->ic_data == NULL)
1396 if (abd_cmp(good_child->ic_data, ic->ic_data,
1400 zio_nowait(zio_vdev_child_io(zio, NULL,
1401 ic->ic_vdev, is->is_target_offset,
1402 good_child->ic_data, is->is_size,
1403 ZIO_TYPE_WRITE, ZIO_PRIORITY_ASYNC_WRITE,
1404 ZIO_FLAG_IO_REPAIR | ZIO_FLAG_SELF_HEAL,
1407 vdev_indirect_checksum_error(zio, is, ic);
1413 * Report checksum errors on all children that we read from.
1416 vdev_indirect_all_checksum_errors(zio_t *zio)
1418 indirect_vsd_t *iv = zio->io_vsd;
1420 if (zio->io_flags & ZIO_FLAG_SPECULATIVE)
1423 for (indirect_split_t *is = list_head(&iv->iv_splits);
1424 is != NULL; is = list_next(&iv->iv_splits, is)) {
1425 for (int c = 0; c < is->is_children; c++) {
1426 indirect_child_t *ic = &is->is_child[c];
1428 if (ic->ic_data == NULL)
1431 vdev_t *vd = ic->ic_vdev;
1433 mutex_enter(&vd->vdev_stat_lock);
1434 vd->vdev_stat.vs_checksum_errors++;
1435 mutex_exit(&vd->vdev_stat_lock);
1437 zfs_ereport_post_checksum(zio->io_spa, vd, zio,
1438 is->is_target_offset, is->is_size,
1445 * This function is called when we have read all copies of the data and need
1446 * to try to find a combination of copies that gives us the right checksum.
1448 * If we pointed to any mirror vdevs, this effectively does the job of the
1449 * mirror. The mirror vdev code can't do its own job because we don't know
1450 * the checksum of each split segment individually. We have to try every
1451 * combination of copies of split segments, until we find one that checksums
1452 * correctly. (Or until we have tried all combinations, or have tried
1453 * 2^zfs_reconstruct_indirect_segments_max combinations. In these cases we
1454 * set io_error to ECKSUM to propagate the error up to the user.)
1456 * For example, if we have 3 segments in the split,
1457 * and each points to a 2-way mirror, we will have the following pieces of
1462 * ======|=====================
1463 * A | data_A_0 data_A_1
1464 * B | data_B_0 data_B_1
1465 * C | data_C_0 data_C_1
1467 * We will try the following (mirror children)^(number of splits) (2^3=8)
1468 * combinations, which is similar to bitwise-little-endian counting in
1469 * binary. In general each "digit" corresponds to a split segment, and the
1470 * base of each digit is is_children, which can be different for each
1473 * "low bit" "high bit"
1475 * data_A_0 data_B_0 data_C_0
1476 * data_A_1 data_B_0 data_C_0
1477 * data_A_0 data_B_1 data_C_0
1478 * data_A_1 data_B_1 data_C_0
1479 * data_A_0 data_B_0 data_C_1
1480 * data_A_1 data_B_0 data_C_1
1481 * data_A_0 data_B_1 data_C_1
1482 * data_A_1 data_B_1 data_C_1
1484 * Note that the split segments may be on the same or different top-level
1485 * vdevs. In either case, we try lots of combinations (see
1486 * zfs_reconstruct_indirect_segments_max). This ensures that if a mirror has
1487 * small silent errors on all of its children, we can still reconstruct the
1488 * correct data, as long as those errors are at sufficiently-separated
1489 * offsets (specifically, separated by the largest block size - default of
1490 * 128KB, but up to 16MB).
1493 vdev_indirect_reconstruct_io_done(zio_t *zio)
1495 indirect_vsd_t *iv = zio->io_vsd;
1496 uint64_t attempts = 0;
1497 uint64_t attempts_max = 1ULL << zfs_reconstruct_indirect_segments_max;
1500 for (indirect_split_t *is = list_head(&iv->iv_splits);
1501 is != NULL; is = list_next(&iv->iv_splits, is))
1505 /* copy data from splits to main zio */
1507 for (indirect_split_t *is = list_head(&iv->iv_splits);
1508 is != NULL; is = list_next(&iv->iv_splits, is)) {
1511 * If this child failed, its ic_data will be NULL.
1512 * Skip this combination.
1514 if (is->is_child[is->is_good_child].ic_data == NULL) {
1519 abd_copy_off(zio->io_abd,
1520 is->is_child[is->is_good_child].ic_data,
1521 is->is_split_offset, 0, is->is_size);
1524 /* See if this checksum matches. */
1525 zio_bad_cksum_t zbc;
1526 ret = zio_checksum_error(zio, &zbc);
1528 /* Found a matching checksum. Issue repair i/os. */
1529 vdev_indirect_repair(zio);
1530 zio_checksum_verified(zio);
1535 * Checksum failed; try a different combination of split
1541 if (segments <= zfs_reconstruct_indirect_segments_max) {
1543 * There are relatively few segments, so
1544 * deterministically check all combinations. We do
1545 * this by by adding one to the first split's
1546 * good_child. If it overflows, then "carry over" to
1547 * the next split (like counting in base is_children,
1548 * but each digit can have a different base).
1550 for (indirect_split_t *is = list_head(&iv->iv_splits);
1551 is != NULL; is = list_next(&iv->iv_splits, is)) {
1552 is->is_good_child++;
1553 if (is->is_good_child < is->is_children) {
1557 is->is_good_child = 0;
1559 } else if (++attempts < attempts_max) {
1561 * There are too many combinations to try all of them
1562 * in a reasonable amount of time, so try a fixed
1563 * number of random combinations, after which we'll
1564 * consider the block unrecoverable.
1566 for (indirect_split_t *is = list_head(&iv->iv_splits);
1567 is != NULL; is = list_next(&iv->iv_splits, is)) {
1569 spa_get_random(is->is_children);
1574 /* All combinations failed. */
1575 zio->io_error = ret;
1576 vdev_indirect_all_checksum_errors(zio);
1577 zio_checksum_verified(zio);
1584 vdev_indirect_io_done(zio_t *zio)
1586 indirect_vsd_t *iv = zio->io_vsd;
1588 if (iv->iv_reconstruct) {
1590 * We have read all copies of the data (e.g. from mirrors),
1591 * either because this was a scrub/resilver, or because the
1592 * one-copy read didn't checksum correctly.
1594 vdev_indirect_reconstruct_io_done(zio);
1598 if (!iv->iv_split_block) {
1600 * This was not a split block, so we passed the BP down,
1601 * and the checksum was handled by the (one) child zio.
1606 zio_bad_cksum_t zbc;
1607 int ret = zio_checksum_error(zio, &zbc);
1609 zio_checksum_verified(zio);
1614 * The checksum didn't match. Read all copies of all splits, and
1615 * then we will try to reconstruct. The next time
1616 * vdev_indirect_io_done() is called, iv_reconstruct will be set.
1618 vdev_indirect_read_all(zio);
1620 zio_vdev_io_redone(zio);
1623 vdev_ops_t vdev_indirect_ops = {
1625 vdev_indirect_close,
1627 vdev_indirect_io_start,
1628 vdev_indirect_io_done,
1633 vdev_indirect_remap,
1635 VDEV_TYPE_INDIRECT, /* name of this vdev type */
1636 B_FALSE /* leaf vdev */