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66 * keep track of how much of each mapping entry is obsolete.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));
729 * Sync task to begin the condensing process.
732 spa_condense_indirect_start_sync(vdev_t *vd, dmu_tx_t *tx)
734 spa_t *spa = vd->vdev_spa;
735 spa_condensing_indirect_phys_t *scip =
736 &spa->spa_condensing_indirect_phys;
738 ASSERT0(scip->scip_next_mapping_object);
739 ASSERT0(scip->scip_prev_obsolete_sm_object);
740 ASSERT0(scip->scip_vdev);
741 ASSERT(dmu_tx_is_syncing(tx));
742 ASSERT3P(vd->vdev_ops, ==, &vdev_indirect_ops);
743 ASSERT(spa_feature_is_active(spa, SPA_FEATURE_OBSOLETE_COUNTS));
744 ASSERT(vdev_indirect_mapping_num_entries(vd->vdev_indirect_mapping));
746 uint64_t obsolete_sm_obj = vdev_obsolete_sm_object(vd);
747 ASSERT(obsolete_sm_obj != 0);
749 scip->scip_vdev = vd->vdev_id;
750 scip->scip_next_mapping_object =
751 vdev_indirect_mapping_alloc(spa->spa_meta_objset, tx);
753 scip->scip_prev_obsolete_sm_object = obsolete_sm_obj;
756 * We don't need to allocate a new space map object, since
757 * vdev_indirect_sync_obsolete will allocate one when needed.
759 space_map_close(vd->vdev_obsolete_sm);
760 vd->vdev_obsolete_sm = NULL;
761 VERIFY0(zap_remove(spa->spa_meta_objset, vd->vdev_top_zap,
762 VDEV_TOP_ZAP_INDIRECT_OBSOLETE_SM, tx));
764 VERIFY0(zap_add(spa->spa_dsl_pool->dp_meta_objset,
765 DMU_POOL_DIRECTORY_OBJECT,
766 DMU_POOL_CONDENSING_INDIRECT, sizeof (uint64_t),
767 sizeof (*scip) / sizeof (uint64_t), scip, tx));
769 ASSERT3P(spa->spa_condensing_indirect, ==, NULL);
770 spa->spa_condensing_indirect = spa_condensing_indirect_create(spa);
772 zfs_dbgmsg("starting condense of vdev %llu in txg %llu: "
774 vd->vdev_id, dmu_tx_get_txg(tx),
775 (u_longlong_t)scip->scip_prev_obsolete_sm_object,
776 (u_longlong_t)scip->scip_next_mapping_object);
778 zthr_wakeup(spa->spa_condense_zthr);
782 * Sync to the given vdev's obsolete space map any segments that are no longer
783 * referenced as of the given txg.
785 * If the obsolete space map doesn't exist yet, create and open it.
788 vdev_indirect_sync_obsolete(vdev_t *vd, dmu_tx_t *tx)
790 spa_t *spa = vd->vdev_spa;
791 vdev_indirect_config_t *vic = &vd->vdev_indirect_config;
793 ASSERT3U(vic->vic_mapping_object, !=, 0);
794 ASSERT(range_tree_space(vd->vdev_obsolete_segments) > 0);
795 ASSERT(vd->vdev_removing || vd->vdev_ops == &vdev_indirect_ops);
796 ASSERT(spa_feature_is_enabled(spa, SPA_FEATURE_OBSOLETE_COUNTS));
798 if (vdev_obsolete_sm_object(vd) == 0) {
799 uint64_t obsolete_sm_object =
800 space_map_alloc(spa->spa_meta_objset,
801 vdev_standard_sm_blksz, tx);
803 ASSERT(vd->vdev_top_zap != 0);
804 VERIFY0(zap_add(vd->vdev_spa->spa_meta_objset, vd->vdev_top_zap,
805 VDEV_TOP_ZAP_INDIRECT_OBSOLETE_SM,
806 sizeof (obsolete_sm_object), 1, &obsolete_sm_object, tx));
807 ASSERT3U(vdev_obsolete_sm_object(vd), !=, 0);
809 spa_feature_incr(spa, SPA_FEATURE_OBSOLETE_COUNTS, tx);
810 VERIFY0(space_map_open(&vd->vdev_obsolete_sm,
811 spa->spa_meta_objset, obsolete_sm_object,
812 0, vd->vdev_asize, 0));
813 space_map_update(vd->vdev_obsolete_sm);
816 ASSERT(vd->vdev_obsolete_sm != NULL);
817 ASSERT3U(vdev_obsolete_sm_object(vd), ==,
818 space_map_object(vd->vdev_obsolete_sm));
820 space_map_write(vd->vdev_obsolete_sm,
821 vd->vdev_obsolete_segments, SM_ALLOC, SM_NO_VDEVID, tx);
822 space_map_update(vd->vdev_obsolete_sm);
823 range_tree_vacate(vd->vdev_obsolete_segments, NULL, NULL);
827 spa_condense_init(spa_t *spa)
829 int error = zap_lookup(spa->spa_meta_objset,
830 DMU_POOL_DIRECTORY_OBJECT,
831 DMU_POOL_CONDENSING_INDIRECT, sizeof (uint64_t),
832 sizeof (spa->spa_condensing_indirect_phys) / sizeof (uint64_t),
833 &spa->spa_condensing_indirect_phys);
835 if (spa_writeable(spa)) {
836 spa->spa_condensing_indirect =
837 spa_condensing_indirect_create(spa);
840 } else if (error == ENOENT) {
848 spa_condense_fini(spa_t *spa)
850 if (spa->spa_condensing_indirect != NULL) {
851 spa_condensing_indirect_destroy(spa->spa_condensing_indirect);
852 spa->spa_condensing_indirect = NULL;
857 spa_start_indirect_condensing_thread(spa_t *spa)
859 ASSERT3P(spa->spa_condense_zthr, ==, NULL);
860 spa->spa_condense_zthr = zthr_create(spa_condense_indirect_thread_check,
861 spa_condense_indirect_thread, spa);
865 * Gets the obsolete spacemap object from the vdev's ZAP.
866 * Returns the spacemap object, or 0 if it wasn't in the ZAP or the ZAP doesn't
870 vdev_obsolete_sm_object(vdev_t *vd)
872 ASSERT0(spa_config_held(vd->vdev_spa, SCL_ALL, RW_WRITER));
873 if (vd->vdev_top_zap == 0) {
878 int err = zap_lookup(vd->vdev_spa->spa_meta_objset, vd->vdev_top_zap,
879 VDEV_TOP_ZAP_INDIRECT_OBSOLETE_SM, sizeof (sm_obj), 1, &sm_obj);
881 ASSERT(err == 0 || err == ENOENT);
887 vdev_obsolete_counts_are_precise(vdev_t *vd)
889 ASSERT0(spa_config_held(vd->vdev_spa, SCL_ALL, RW_WRITER));
890 if (vd->vdev_top_zap == 0) {
895 int err = zap_lookup(vd->vdev_spa->spa_meta_objset, vd->vdev_top_zap,
896 VDEV_TOP_ZAP_OBSOLETE_COUNTS_ARE_PRECISE, sizeof (val), 1, &val);
898 ASSERT(err == 0 || err == ENOENT);
905 vdev_indirect_close(vdev_t *vd)
911 vdev_indirect_open(vdev_t *vd, uint64_t *psize, uint64_t *max_psize,
912 uint64_t *logical_ashift, uint64_t *physical_ashift)
914 *psize = *max_psize = vd->vdev_asize +
915 VDEV_LABEL_START_SIZE + VDEV_LABEL_END_SIZE;
916 *logical_ashift = vd->vdev_ashift;
917 *physical_ashift = vd->vdev_physical_ashift;
921 typedef struct remap_segment {
925 uint64_t rs_split_offset;
930 rs_alloc(vdev_t *vd, uint64_t offset, uint64_t asize, uint64_t split_offset)
932 remap_segment_t *rs = kmem_alloc(sizeof (remap_segment_t), KM_SLEEP);
934 rs->rs_offset = offset;
935 rs->rs_asize = asize;
936 rs->rs_split_offset = split_offset;
941 * Given an indirect vdev and an extent on that vdev, it duplicates the
942 * physical entries of the indirect mapping that correspond to the extent
943 * to a new array and returns a pointer to it. In addition, copied_entries
944 * is populated with the number of mapping entries that were duplicated.
946 * Note that the function assumes that the caller holds vdev_indirect_rwlock.
947 * This ensures that the mapping won't change due to condensing as we
948 * copy over its contents.
950 * Finally, since we are doing an allocation, it is up to the caller to
951 * free the array allocated in this function.
953 vdev_indirect_mapping_entry_phys_t *
954 vdev_indirect_mapping_duplicate_adjacent_entries(vdev_t *vd, uint64_t offset,
955 uint64_t asize, uint64_t *copied_entries)
957 vdev_indirect_mapping_entry_phys_t *duplicate_mappings = NULL;
958 vdev_indirect_mapping_t *vim = vd->vdev_indirect_mapping;
959 uint64_t entries = 0;
961 ASSERT(RW_READ_HELD(&vd->vdev_indirect_rwlock));
963 vdev_indirect_mapping_entry_phys_t *first_mapping =
964 vdev_indirect_mapping_entry_for_offset(vim, offset);
965 ASSERT3P(first_mapping, !=, NULL);
967 vdev_indirect_mapping_entry_phys_t *m = first_mapping;
969 uint64_t size = DVA_GET_ASIZE(&m->vimep_dst);
971 ASSERT3U(offset, >=, DVA_MAPPING_GET_SRC_OFFSET(m));
972 ASSERT3U(offset, <, DVA_MAPPING_GET_SRC_OFFSET(m) + size);
974 uint64_t inner_offset = offset - DVA_MAPPING_GET_SRC_OFFSET(m);
975 uint64_t inner_size = MIN(asize, size - inner_offset);
977 offset += inner_size;
983 size_t copy_length = entries * sizeof (*first_mapping);
984 duplicate_mappings = kmem_alloc(copy_length, KM_SLEEP);
985 bcopy(first_mapping, duplicate_mappings, copy_length);
986 *copied_entries = entries;
988 return (duplicate_mappings);
992 * Goes through the relevant indirect mappings until it hits a concrete vdev
993 * and issues the callback. On the way to the concrete vdev, if any other
994 * indirect vdevs are encountered, then the callback will also be called on
995 * each of those indirect vdevs. For example, if the segment is mapped to
996 * segment A on indirect vdev 1, and then segment A on indirect vdev 1 is
997 * mapped to segment B on concrete vdev 2, then the callback will be called on
998 * both vdev 1 and vdev 2.
1000 * While the callback passed to vdev_indirect_remap() is called on every vdev
1001 * the function encounters, certain callbacks only care about concrete vdevs.
1002 * These types of callbacks should return immediately and explicitly when they
1003 * are called on an indirect vdev.
1005 * Because there is a possibility that a DVA section in the indirect device
1006 * has been split into multiple sections in our mapping, we keep track
1007 * of the relevant contiguous segments of the new location (remap_segment_t)
1008 * in a stack. This way we can call the callback for each of the new sections
1009 * created by a single section of the indirect device. Note though, that in
1010 * this scenario the callbacks in each split block won't occur in-order in
1011 * terms of offset, so callers should not make any assumptions about that.
1013 * For callbacks that don't handle split blocks and immediately return when
1014 * they encounter them (as is the case for remap_blkptr_cb), the caller can
1015 * assume that its callback will be applied from the first indirect vdev
1016 * encountered to the last one and then the concrete vdev, in that order.
1019 vdev_indirect_remap(vdev_t *vd, uint64_t offset, uint64_t asize,
1020 void (*func)(uint64_t, vdev_t *, uint64_t, uint64_t, void *), void *arg)
1023 spa_t *spa = vd->vdev_spa;
1025 list_create(&stack, sizeof (remap_segment_t),
1026 offsetof(remap_segment_t, rs_node));
1028 for (remap_segment_t *rs = rs_alloc(vd, offset, asize, 0);
1029 rs != NULL; rs = list_remove_head(&stack)) {
1030 vdev_t *v = rs->rs_vd;
1031 uint64_t num_entries = 0;
1033 ASSERT(spa_config_held(spa, SCL_ALL, RW_READER) != 0);
1034 ASSERT(rs->rs_asize > 0);
1037 * Note: As this function can be called from open context
1038 * (e.g. zio_read()), we need the following rwlock to
1039 * prevent the mapping from being changed by condensing.
1041 * So we grab the lock and we make a copy of the entries
1042 * that are relevant to the extent that we are working on.
1043 * Once that is done, we drop the lock and iterate over
1044 * our copy of the mapping. Once we are done with the with
1045 * the remap segment and we free it, we also free our copy
1046 * of the indirect mapping entries that are relevant to it.
1048 * This way we don't need to wait until the function is
1049 * finished with a segment, to condense it. In addition, we
1050 * don't need a recursive rwlock for the case that a call to
1051 * vdev_indirect_remap() needs to call itself (through the
1052 * codepath of its callback) for the same vdev in the middle
1055 rw_enter(&v->vdev_indirect_rwlock, RW_READER);
1056 vdev_indirect_mapping_t *vim = v->vdev_indirect_mapping;
1057 ASSERT3P(vim, !=, NULL);
1059 vdev_indirect_mapping_entry_phys_t *mapping =
1060 vdev_indirect_mapping_duplicate_adjacent_entries(v,
1061 rs->rs_offset, rs->rs_asize, &num_entries);
1062 ASSERT3P(mapping, !=, NULL);
1063 ASSERT3U(num_entries, >, 0);
1064 rw_exit(&v->vdev_indirect_rwlock);
1066 for (uint64_t i = 0; i < num_entries; i++) {
1068 * Note: the vdev_indirect_mapping can not change
1069 * while we are running. It only changes while the
1070 * removal is in progress, and then only from syncing
1071 * context. While a removal is in progress, this
1072 * function is only called for frees, which also only
1073 * happen from syncing context.
1075 vdev_indirect_mapping_entry_phys_t *m = &mapping[i];
1077 ASSERT3P(m, !=, NULL);
1078 ASSERT3U(rs->rs_asize, >, 0);
1080 uint64_t size = DVA_GET_ASIZE(&m->vimep_dst);
1081 uint64_t dst_offset = DVA_GET_OFFSET(&m->vimep_dst);
1082 uint64_t dst_vdev = DVA_GET_VDEV(&m->vimep_dst);
1084 ASSERT3U(rs->rs_offset, >=,
1085 DVA_MAPPING_GET_SRC_OFFSET(m));
1086 ASSERT3U(rs->rs_offset, <,
1087 DVA_MAPPING_GET_SRC_OFFSET(m) + size);
1088 ASSERT3U(dst_vdev, !=, v->vdev_id);
1090 uint64_t inner_offset = rs->rs_offset -
1091 DVA_MAPPING_GET_SRC_OFFSET(m);
1092 uint64_t inner_size =
1093 MIN(rs->rs_asize, size - inner_offset);
1095 vdev_t *dst_v = vdev_lookup_top(spa, dst_vdev);
1096 ASSERT3P(dst_v, !=, NULL);
1098 if (dst_v->vdev_ops == &vdev_indirect_ops) {
1099 list_insert_head(&stack,
1100 rs_alloc(dst_v, dst_offset + inner_offset,
1101 inner_size, rs->rs_split_offset));
1105 if ((zfs_flags & ZFS_DEBUG_INDIRECT_REMAP) &&
1106 IS_P2ALIGNED(inner_size, 2 * SPA_MINBLOCKSIZE)) {
1108 * Note: This clause exists only solely for
1109 * testing purposes. We use it to ensure that
1110 * split blocks work and that the callbacks
1111 * using them yield the same result if issued
1114 uint64_t inner_half = inner_size / 2;
1116 func(rs->rs_split_offset + inner_half, dst_v,
1117 dst_offset + inner_offset + inner_half,
1120 func(rs->rs_split_offset, dst_v,
1121 dst_offset + inner_offset,
1124 func(rs->rs_split_offset, dst_v,
1125 dst_offset + inner_offset,
1129 rs->rs_offset += inner_size;
1130 rs->rs_asize -= inner_size;
1131 rs->rs_split_offset += inner_size;
1133 VERIFY0(rs->rs_asize);
1135 kmem_free(mapping, num_entries * sizeof (*mapping));
1136 kmem_free(rs, sizeof (remap_segment_t));
1138 list_destroy(&stack);
1142 vdev_indirect_child_io_done(zio_t *zio)
1144 zio_t *pio = zio->io_private;
1146 mutex_enter(&pio->io_lock);
1147 pio->io_error = zio_worst_error(pio->io_error, zio->io_error);
1148 mutex_exit(&pio->io_lock);
1151 if (zio->io_abd != NULL)
1153 abd_put(zio->io_abd);
1157 * This is a callback for vdev_indirect_remap() which allocates an
1158 * indirect_split_t for each split segment and adds it to iv_splits.
1161 vdev_indirect_gather_splits(uint64_t split_offset, vdev_t *vd, uint64_t offset,
1162 uint64_t size, void *arg)
1165 indirect_vsd_t *iv = zio->io_vsd;
1167 ASSERT3P(vd, !=, NULL);
1169 if (vd->vdev_ops == &vdev_indirect_ops)
1173 if (vd->vdev_ops == &vdev_mirror_ops)
1174 n = vd->vdev_children;
1176 indirect_split_t *is =
1177 kmem_zalloc(offsetof(indirect_split_t, is_child[n]), KM_SLEEP);
1179 is->is_children = n;
1181 is->is_split_offset = split_offset;
1182 is->is_target_offset = offset;
1186 * Note that we only consider multiple copies of the data for
1187 * *mirror* vdevs. We don't for "replacing" or "spare" vdevs, even
1188 * though they use the same ops as mirror, because there's only one
1189 * "good" copy under the replacing/spare.
1191 if (vd->vdev_ops == &vdev_mirror_ops) {
1192 for (int i = 0; i < n; i++) {
1193 is->is_child[i].ic_vdev = vd->vdev_child[i];
1196 is->is_child[0].ic_vdev = vd;
1199 list_insert_tail(&iv->iv_splits, is);
1203 vdev_indirect_read_split_done(zio_t *zio)
1205 indirect_child_t *ic = zio->io_private;
1207 if (zio->io_error != 0) {
1209 * Clear ic_data to indicate that we do not have data for this
1212 abd_free(ic->ic_data);
1218 * Issue reads for all copies (mirror children) of all splits.
1221 vdev_indirect_read_all(zio_t *zio)
1223 indirect_vsd_t *iv = zio->io_vsd;
1225 for (indirect_split_t *is = list_head(&iv->iv_splits);
1226 is != NULL; is = list_next(&iv->iv_splits, is)) {
1227 for (int i = 0; i < is->is_children; i++) {
1228 indirect_child_t *ic = &is->is_child[i];
1230 if (!vdev_readable(ic->ic_vdev))
1234 * Note, we may read from a child whose DTL
1235 * indicates that the data may not be present here.
1236 * While this might result in a few i/os that will
1237 * likely return incorrect data, it simplifies the
1238 * code since we can treat scrub and resilver
1239 * identically. (The incorrect data will be
1240 * detected and ignored when we verify the
1244 ic->ic_data = abd_alloc_sametype(zio->io_abd,
1247 zio_nowait(zio_vdev_child_io(zio, NULL,
1248 ic->ic_vdev, is->is_target_offset, ic->ic_data,
1249 is->is_size, zio->io_type, zio->io_priority, 0,
1250 vdev_indirect_read_split_done, ic));
1253 iv->iv_reconstruct = B_TRUE;
1257 vdev_indirect_io_start(zio_t *zio)
1259 spa_t *spa = zio->io_spa;
1260 indirect_vsd_t *iv = kmem_zalloc(sizeof (*iv), KM_SLEEP);
1261 list_create(&iv->iv_splits,
1262 sizeof (indirect_split_t), offsetof(indirect_split_t, is_node));
1265 zio->io_vsd_ops = &vdev_indirect_vsd_ops;
1267 ASSERT(spa_config_held(spa, SCL_ALL, RW_READER) != 0);
1269 if (zio->io_type == ZIO_TYPE_WRITE) {
1271 if (zio->io_type != ZIO_TYPE_READ) {
1272 ASSERT3U(zio->io_type, ==, ZIO_TYPE_WRITE);
1275 * Note: this code can handle other kinds of writes,
1276 * but we don't expect them.
1278 ASSERT((zio->io_flags & (ZIO_FLAG_SELF_HEAL |
1279 ZIO_FLAG_RESILVER | ZIO_FLAG_INDUCE_DAMAGE)) != 0);
1282 vdev_indirect_remap(zio->io_vd, zio->io_offset, zio->io_size,
1283 vdev_indirect_gather_splits, zio);
1285 indirect_split_t *first = list_head(&iv->iv_splits);
1286 if (first->is_size == zio->io_size) {
1288 * This is not a split block; we are pointing to the entire
1289 * data, which will checksum the same as the original data.
1290 * Pass the BP down so that the child i/o can verify the
1291 * checksum, and try a different location if available
1292 * (e.g. on a mirror).
1294 * While this special case could be handled the same as the
1295 * general (split block) case, doing it this way ensures
1296 * that the vast majority of blocks on indirect vdevs
1297 * (which are not split) are handled identically to blocks
1298 * on non-indirect vdevs. This allows us to be less strict
1299 * about performance in the general (but rare) case.
1301 ASSERT0(first->is_split_offset);
1302 ASSERT3P(list_next(&iv->iv_splits, first), ==, NULL);
1303 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
1304 first->is_vdev, first->is_target_offset,
1306 zio->io_abd == NULL ? NULL :
1308 abd_get_offset(zio->io_abd, 0),
1309 zio->io_size, zio->io_type, zio->io_priority, 0,
1310 vdev_indirect_child_io_done, zio));
1312 iv->iv_split_block = B_TRUE;
1313 if (zio->io_flags & (ZIO_FLAG_SCRUB | ZIO_FLAG_RESILVER)) {
1315 * Read all copies. Note that for simplicity,
1316 * we don't bother consulting the DTL in the
1319 vdev_indirect_read_all(zio);
1322 * Read one copy of each split segment, from the
1323 * top-level vdev. Since we don't know the
1324 * checksum of each split individually, the child
1325 * zio can't ensure that we get the right data.
1326 * E.g. if it's a mirror, it will just read from a
1327 * random (healthy) leaf vdev. We have to verify
1328 * the checksum in vdev_indirect_io_done().
1330 for (indirect_split_t *is = list_head(&iv->iv_splits);
1331 is != NULL; is = list_next(&iv->iv_splits, is)) {
1332 zio_nowait(zio_vdev_child_io(zio, NULL,
1333 is->is_vdev, is->is_target_offset,
1335 zio->io_abd == NULL ? NULL :
1337 abd_get_offset(zio->io_abd,
1338 is->is_split_offset),
1339 is->is_size, zio->io_type,
1340 zio->io_priority, 0,
1341 vdev_indirect_child_io_done, zio));
1350 * Report a checksum error for a child.
1353 vdev_indirect_checksum_error(zio_t *zio,
1354 indirect_split_t *is, indirect_child_t *ic)
1356 vdev_t *vd = ic->ic_vdev;
1358 if (zio->io_flags & ZIO_FLAG_SPECULATIVE)
1361 mutex_enter(&vd->vdev_stat_lock);
1362 vd->vdev_stat.vs_checksum_errors++;
1363 mutex_exit(&vd->vdev_stat_lock);
1365 zio_bad_cksum_t zbc = { 0 };
1366 void *bad_buf = abd_borrow_buf_copy(ic->ic_data, is->is_size);
1367 abd_t *good_abd = is->is_child[is->is_good_child].ic_data;
1368 void *good_buf = abd_borrow_buf_copy(good_abd, is->is_size);
1369 zfs_ereport_post_checksum(zio->io_spa, vd, zio,
1370 is->is_target_offset, is->is_size, good_buf, bad_buf, &zbc);
1371 abd_return_buf(ic->ic_data, bad_buf, is->is_size);
1372 abd_return_buf(good_abd, good_buf, is->is_size);
1376 * Issue repair i/os for any incorrect copies. We do this by comparing
1377 * each split segment's correct data (is_good_child's ic_data) with each
1378 * other copy of the data. If they differ, then we overwrite the bad data
1379 * with the good copy. Note that we do this without regard for the DTL's,
1380 * which simplifies this code and also issues the optimal number of writes
1381 * (based on which copies actually read bad data, as opposed to which we
1382 * think might be wrong). For the same reason, we always use
1383 * ZIO_FLAG_SELF_HEAL, to bypass the DTL check in zio_vdev_io_start().
1386 vdev_indirect_repair(zio_t *zio)
1388 indirect_vsd_t *iv = zio->io_vsd;
1390 enum zio_flag flags = ZIO_FLAG_IO_REPAIR;
1392 if (!(zio->io_flags & (ZIO_FLAG_SCRUB | ZIO_FLAG_RESILVER)))
1393 flags |= ZIO_FLAG_SELF_HEAL;
1395 if (!spa_writeable(zio->io_spa))
1398 for (indirect_split_t *is = list_head(&iv->iv_splits);
1399 is != NULL; is = list_next(&iv->iv_splits, is)) {
1400 indirect_child_t *good_child = &is->is_child[is->is_good_child];
1402 for (int c = 0; c < is->is_children; c++) {
1403 indirect_child_t *ic = &is->is_child[c];
1404 if (ic == good_child)
1406 if (ic->ic_data == NULL)
1408 if (abd_cmp(good_child->ic_data, ic->ic_data,
1412 zio_nowait(zio_vdev_child_io(zio, NULL,
1413 ic->ic_vdev, is->is_target_offset,
1414 good_child->ic_data, is->is_size,
1415 ZIO_TYPE_WRITE, ZIO_PRIORITY_ASYNC_WRITE,
1416 ZIO_FLAG_IO_REPAIR | ZIO_FLAG_SELF_HEAL,
1419 vdev_indirect_checksum_error(zio, is, ic);
1425 * Report checksum errors on all children that we read from.
1428 vdev_indirect_all_checksum_errors(zio_t *zio)
1430 indirect_vsd_t *iv = zio->io_vsd;
1432 if (zio->io_flags & ZIO_FLAG_SPECULATIVE)
1435 for (indirect_split_t *is = list_head(&iv->iv_splits);
1436 is != NULL; is = list_next(&iv->iv_splits, is)) {
1437 for (int c = 0; c < is->is_children; c++) {
1438 indirect_child_t *ic = &is->is_child[c];
1440 if (ic->ic_data == NULL)
1443 vdev_t *vd = ic->ic_vdev;
1445 mutex_enter(&vd->vdev_stat_lock);
1446 vd->vdev_stat.vs_checksum_errors++;
1447 mutex_exit(&vd->vdev_stat_lock);
1449 zfs_ereport_post_checksum(zio->io_spa, vd, zio,
1450 is->is_target_offset, is->is_size,
1457 * This function is called when we have read all copies of the data and need
1458 * to try to find a combination of copies that gives us the right checksum.
1460 * If we pointed to any mirror vdevs, this effectively does the job of the
1461 * mirror. The mirror vdev code can't do its own job because we don't know
1462 * the checksum of each split segment individually. We have to try every
1463 * combination of copies of split segments, until we find one that checksums
1464 * correctly. (Or until we have tried all combinations, or have tried
1465 * 2^zfs_reconstruct_indirect_segments_max combinations. In these cases we
1466 * set io_error to ECKSUM to propagate the error up to the user.)
1468 * For example, if we have 3 segments in the split,
1469 * and each points to a 2-way mirror, we will have the following pieces of
1474 * ======|=====================
1475 * A | data_A_0 data_A_1
1476 * B | data_B_0 data_B_1
1477 * C | data_C_0 data_C_1
1479 * We will try the following (mirror children)^(number of splits) (2^3=8)
1480 * combinations, which is similar to bitwise-little-endian counting in
1481 * binary. In general each "digit" corresponds to a split segment, and the
1482 * base of each digit is is_children, which can be different for each
1485 * "low bit" "high bit"
1487 * data_A_0 data_B_0 data_C_0
1488 * data_A_1 data_B_0 data_C_0
1489 * data_A_0 data_B_1 data_C_0
1490 * data_A_1 data_B_1 data_C_0
1491 * data_A_0 data_B_0 data_C_1
1492 * data_A_1 data_B_0 data_C_1
1493 * data_A_0 data_B_1 data_C_1
1494 * data_A_1 data_B_1 data_C_1
1496 * Note that the split segments may be on the same or different top-level
1497 * vdevs. In either case, we try lots of combinations (see
1498 * zfs_reconstruct_indirect_segments_max). This ensures that if a mirror has
1499 * small silent errors on all of its children, we can still reconstruct the
1500 * correct data, as long as those errors are at sufficiently-separated
1501 * offsets (specifically, separated by the largest block size - default of
1502 * 128KB, but up to 16MB).
1505 vdev_indirect_reconstruct_io_done(zio_t *zio)
1507 indirect_vsd_t *iv = zio->io_vsd;
1508 uint64_t attempts = 0;
1509 uint64_t attempts_max = 1ULL << zfs_reconstruct_indirect_segments_max;
1512 for (indirect_split_t *is = list_head(&iv->iv_splits);
1513 is != NULL; is = list_next(&iv->iv_splits, is))
1517 /* copy data from splits to main zio */
1519 for (indirect_split_t *is = list_head(&iv->iv_splits);
1520 is != NULL; is = list_next(&iv->iv_splits, is)) {
1523 * If this child failed, its ic_data will be NULL.
1524 * Skip this combination.
1526 if (is->is_child[is->is_good_child].ic_data == NULL) {
1531 abd_copy_off(zio->io_abd,
1532 is->is_child[is->is_good_child].ic_data,
1533 is->is_split_offset, 0, is->is_size);
1536 /* See if this checksum matches. */
1537 zio_bad_cksum_t zbc;
1538 ret = zio_checksum_error(zio, &zbc);
1540 /* Found a matching checksum. Issue repair i/os. */
1541 vdev_indirect_repair(zio);
1542 zio_checksum_verified(zio);
1547 * Checksum failed; try a different combination of split
1553 if (segments <= zfs_reconstruct_indirect_segments_max) {
1555 * There are relatively few segments, so
1556 * deterministically check all combinations. We do
1557 * this by by adding one to the first split's
1558 * good_child. If it overflows, then "carry over" to
1559 * the next split (like counting in base is_children,
1560 * but each digit can have a different base).
1562 for (indirect_split_t *is = list_head(&iv->iv_splits);
1563 is != NULL; is = list_next(&iv->iv_splits, is)) {
1564 is->is_good_child++;
1565 if (is->is_good_child < is->is_children) {
1569 is->is_good_child = 0;
1571 } else if (++attempts < attempts_max) {
1573 * There are too many combinations to try all of them
1574 * in a reasonable amount of time, so try a fixed
1575 * number of random combinations, after which we'll
1576 * consider the block unrecoverable.
1578 for (indirect_split_t *is = list_head(&iv->iv_splits);
1579 is != NULL; is = list_next(&iv->iv_splits, is)) {
1581 spa_get_random(is->is_children);
1586 /* All combinations failed. */
1587 zio->io_error = ret;
1588 vdev_indirect_all_checksum_errors(zio);
1589 zio_checksum_verified(zio);
1596 vdev_indirect_io_done(zio_t *zio)
1598 indirect_vsd_t *iv = zio->io_vsd;
1600 if (iv->iv_reconstruct) {
1602 * We have read all copies of the data (e.g. from mirrors),
1603 * either because this was a scrub/resilver, or because the
1604 * one-copy read didn't checksum correctly.
1606 vdev_indirect_reconstruct_io_done(zio);
1610 if (!iv->iv_split_block) {
1612 * This was not a split block, so we passed the BP down,
1613 * and the checksum was handled by the (one) child zio.
1618 zio_bad_cksum_t zbc;
1619 int ret = zio_checksum_error(zio, &zbc);
1621 zio_checksum_verified(zio);
1626 * The checksum didn't match. Read all copies of all splits, and
1627 * then we will try to reconstruct. The next time
1628 * vdev_indirect_io_done() is called, iv_reconstruct will be set.
1630 vdev_indirect_read_all(zio);
1632 zio_vdev_io_redone(zio);
1635 vdev_ops_t vdev_indirect_ops = {
1637 vdev_indirect_close,
1639 vdev_indirect_io_start,
1640 vdev_indirect_io_done,
1645 vdev_indirect_remap,
1647 VDEV_TYPE_INDIRECT, /* name of this vdev type */
1648 B_FALSE /* leaf vdev */