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66 * keep track of how much of each mapping entry is obsolete.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 int 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 unsigned long 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 unsigned long 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_ms
= 0;
209 * If an indirect split block contains more than this many possible unique
210 * combinations when being reconstructed, consider it too computationally
211 * expensive to check them all. Instead, try at most 100 randomly-selected
212 * combinations each time the block is accessed. This allows all segment
213 * copies to participate fairly in the reconstruction when all combinations
214 * cannot be checked and prevents repeated use of one bad copy.
216 int zfs_reconstruct_indirect_combinations_max
= 256;
220 * Enable to simulate damaged segments and validate reconstruction. This
221 * is intentionally not exposed as a module parameter.
223 unsigned long zfs_reconstruct_indirect_damage_fraction
= 0;
226 * The indirect_child_t represents the vdev that we will read from, when we
227 * need to read all copies of the data (e.g. for scrub or reconstruction).
228 * For plain (non-mirror) top-level vdevs (i.e. is_vdev is not a mirror),
229 * ic_vdev is the same as is_vdev. However, for mirror top-level vdevs,
230 * ic_vdev is a child of the mirror.
232 typedef struct indirect_child
{
237 * ic_duplicate is NULL when the ic_data contents are unique, when it
238 * is determined to be a duplicate it references the primary child.
240 struct indirect_child
*ic_duplicate
;
241 list_node_t ic_node
; /* node on is_unique_child */
245 * The indirect_split_t represents one mapped segment of an i/o to the
246 * indirect vdev. For non-split (contiguously-mapped) blocks, there will be
247 * only one indirect_split_t, with is_split_offset==0 and is_size==io_size.
248 * For split blocks, there will be several of these.
250 typedef struct indirect_split
{
251 list_node_t is_node
; /* link on iv_splits */
254 * is_split_offset is the offset into the i/o.
255 * This is the sum of the previous splits' is_size's.
257 uint64_t is_split_offset
;
259 vdev_t
*is_vdev
; /* top-level vdev */
260 uint64_t is_target_offset
; /* offset on is_vdev */
262 int is_children
; /* number of entries in is_child[] */
263 int is_unique_children
; /* number of entries in is_unique_child */
264 list_t is_unique_child
;
267 * is_good_child is the child that we are currently using to
268 * attempt reconstruction.
270 indirect_child_t
*is_good_child
;
272 indirect_child_t is_child
[1]; /* variable-length */
276 * The indirect_vsd_t is associated with each i/o to the indirect vdev.
277 * It is the "Vdev-Specific Data" in the zio_t's io_vsd.
279 typedef struct indirect_vsd
{
280 boolean_t iv_split_block
;
281 boolean_t iv_reconstruct
;
282 uint64_t iv_unique_combinations
;
283 uint64_t iv_attempts
;
284 uint64_t iv_attempts_max
;
286 list_t iv_splits
; /* list of indirect_split_t's */
290 vdev_indirect_map_free(zio_t
*zio
)
292 indirect_vsd_t
*iv
= zio
->io_vsd
;
294 indirect_split_t
*is
;
295 while ((is
= list_head(&iv
->iv_splits
)) != NULL
) {
296 for (int c
= 0; c
< is
->is_children
; c
++) {
297 indirect_child_t
*ic
= &is
->is_child
[c
];
298 if (ic
->ic_data
!= NULL
)
299 abd_free(ic
->ic_data
);
301 list_remove(&iv
->iv_splits
, is
);
303 indirect_child_t
*ic
;
304 while ((ic
= list_head(&is
->is_unique_child
)) != NULL
)
305 list_remove(&is
->is_unique_child
, ic
);
307 list_destroy(&is
->is_unique_child
);
310 offsetof(indirect_split_t
, is_child
[is
->is_children
]));
312 kmem_free(iv
, sizeof (*iv
));
315 static const zio_vsd_ops_t vdev_indirect_vsd_ops
= {
316 .vsd_free
= vdev_indirect_map_free
,
317 .vsd_cksum_report
= zio_vsd_default_cksum_report
321 * Mark the given offset and size as being obsolete.
324 vdev_indirect_mark_obsolete(vdev_t
*vd
, uint64_t offset
, uint64_t size
)
326 spa_t
*spa
= vd
->vdev_spa
;
328 ASSERT3U(vd
->vdev_indirect_config
.vic_mapping_object
, !=, 0);
329 ASSERT(vd
->vdev_removing
|| vd
->vdev_ops
== &vdev_indirect_ops
);
331 VERIFY(vdev_indirect_mapping_entry_for_offset(
332 vd
->vdev_indirect_mapping
, offset
) != NULL
);
334 if (spa_feature_is_enabled(spa
, SPA_FEATURE_OBSOLETE_COUNTS
)) {
335 mutex_enter(&vd
->vdev_obsolete_lock
);
336 range_tree_add(vd
->vdev_obsolete_segments
, offset
, size
);
337 mutex_exit(&vd
->vdev_obsolete_lock
);
338 vdev_dirty(vd
, 0, NULL
, spa_syncing_txg(spa
));
343 * Mark the DVA vdev_id:offset:size as being obsolete in the given tx. This
344 * wrapper is provided because the DMU does not know about vdev_t's and
345 * cannot directly call vdev_indirect_mark_obsolete.
348 spa_vdev_indirect_mark_obsolete(spa_t
*spa
, uint64_t vdev_id
, uint64_t offset
,
349 uint64_t size
, dmu_tx_t
*tx
)
351 vdev_t
*vd
= vdev_lookup_top(spa
, vdev_id
);
352 ASSERT(dmu_tx_is_syncing(tx
));
354 /* The DMU can only remap indirect vdevs. */
355 ASSERT3P(vd
->vdev_ops
, ==, &vdev_indirect_ops
);
356 vdev_indirect_mark_obsolete(vd
, offset
, size
);
359 static spa_condensing_indirect_t
*
360 spa_condensing_indirect_create(spa_t
*spa
)
362 spa_condensing_indirect_phys_t
*scip
=
363 &spa
->spa_condensing_indirect_phys
;
364 spa_condensing_indirect_t
*sci
= kmem_zalloc(sizeof (*sci
), KM_SLEEP
);
365 objset_t
*mos
= spa
->spa_meta_objset
;
367 for (int i
= 0; i
< TXG_SIZE
; i
++) {
368 list_create(&sci
->sci_new_mapping_entries
[i
],
369 sizeof (vdev_indirect_mapping_entry_t
),
370 offsetof(vdev_indirect_mapping_entry_t
, vime_node
));
373 sci
->sci_new_mapping
=
374 vdev_indirect_mapping_open(mos
, scip
->scip_next_mapping_object
);
380 spa_condensing_indirect_destroy(spa_condensing_indirect_t
*sci
)
382 for (int i
= 0; i
< TXG_SIZE
; i
++)
383 list_destroy(&sci
->sci_new_mapping_entries
[i
]);
385 if (sci
->sci_new_mapping
!= NULL
)
386 vdev_indirect_mapping_close(sci
->sci_new_mapping
);
388 kmem_free(sci
, sizeof (*sci
));
392 vdev_indirect_should_condense(vdev_t
*vd
)
394 vdev_indirect_mapping_t
*vim
= vd
->vdev_indirect_mapping
;
395 spa_t
*spa
= vd
->vdev_spa
;
397 ASSERT(dsl_pool_sync_context(spa
->spa_dsl_pool
));
399 if (!zfs_condense_indirect_vdevs_enable
)
403 * We can only condense one indirect vdev at a time.
405 if (spa
->spa_condensing_indirect
!= NULL
)
408 if (spa_shutting_down(spa
))
412 * The mapping object size must not change while we are
413 * condensing, so we can only condense indirect vdevs
414 * (not vdevs that are still in the middle of being removed).
416 if (vd
->vdev_ops
!= &vdev_indirect_ops
)
420 * If nothing new has been marked obsolete, there is no
421 * point in condensing.
423 ASSERTV(uint64_t obsolete_sm_obj
);
424 ASSERT0(vdev_obsolete_sm_object(vd
, &obsolete_sm_obj
));
425 if (vd
->vdev_obsolete_sm
== NULL
) {
426 ASSERT0(obsolete_sm_obj
);
430 ASSERT(vd
->vdev_obsolete_sm
!= NULL
);
432 ASSERT3U(obsolete_sm_obj
, ==, space_map_object(vd
->vdev_obsolete_sm
));
434 uint64_t bytes_mapped
= vdev_indirect_mapping_bytes_mapped(vim
);
435 uint64_t bytes_obsolete
= space_map_allocated(vd
->vdev_obsolete_sm
);
436 uint64_t mapping_size
= vdev_indirect_mapping_size(vim
);
437 uint64_t obsolete_sm_size
= space_map_length(vd
->vdev_obsolete_sm
);
439 ASSERT3U(bytes_obsolete
, <=, bytes_mapped
);
442 * If a high percentage of the bytes that are mapped have become
443 * obsolete, condense (unless the mapping is already small enough).
444 * This has a good chance of reducing the amount of memory used
447 if (bytes_obsolete
* 100 / bytes_mapped
>=
448 zfs_indirect_condense_obsolete_pct
&&
449 mapping_size
> zfs_condense_min_mapping_bytes
) {
450 zfs_dbgmsg("should condense vdev %llu because obsolete "
451 "spacemap covers %d%% of %lluMB mapping",
452 (u_longlong_t
)vd
->vdev_id
,
453 (int)(bytes_obsolete
* 100 / bytes_mapped
),
454 (u_longlong_t
)bytes_mapped
/ 1024 / 1024);
459 * If the obsolete space map takes up too much space on disk,
460 * condense in order to free up this disk space.
462 if (obsolete_sm_size
>= zfs_condense_max_obsolete_bytes
) {
463 zfs_dbgmsg("should condense vdev %llu because obsolete sm "
464 "length %lluMB >= max size %lluMB",
465 (u_longlong_t
)vd
->vdev_id
,
466 (u_longlong_t
)obsolete_sm_size
/ 1024 / 1024,
467 (u_longlong_t
)zfs_condense_max_obsolete_bytes
/
476 * This sync task completes (finishes) a condense, deleting the old
477 * mapping and replacing it with the new one.
480 spa_condense_indirect_complete_sync(void *arg
, dmu_tx_t
*tx
)
482 spa_condensing_indirect_t
*sci
= arg
;
483 spa_t
*spa
= dmu_tx_pool(tx
)->dp_spa
;
484 spa_condensing_indirect_phys_t
*scip
=
485 &spa
->spa_condensing_indirect_phys
;
486 vdev_t
*vd
= vdev_lookup_top(spa
, scip
->scip_vdev
);
487 vdev_indirect_config_t
*vic
= &vd
->vdev_indirect_config
;
488 objset_t
*mos
= spa
->spa_meta_objset
;
489 vdev_indirect_mapping_t
*old_mapping
= vd
->vdev_indirect_mapping
;
490 uint64_t old_count
= vdev_indirect_mapping_num_entries(old_mapping
);
492 vdev_indirect_mapping_num_entries(sci
->sci_new_mapping
);
494 ASSERT(dmu_tx_is_syncing(tx
));
495 ASSERT3P(vd
->vdev_ops
, ==, &vdev_indirect_ops
);
496 ASSERT3P(sci
, ==, spa
->spa_condensing_indirect
);
497 for (int i
= 0; i
< TXG_SIZE
; i
++) {
498 ASSERT(list_is_empty(&sci
->sci_new_mapping_entries
[i
]));
500 ASSERT(vic
->vic_mapping_object
!= 0);
501 ASSERT3U(vd
->vdev_id
, ==, scip
->scip_vdev
);
502 ASSERT(scip
->scip_next_mapping_object
!= 0);
503 ASSERT(scip
->scip_prev_obsolete_sm_object
!= 0);
506 * Reset vdev_indirect_mapping to refer to the new object.
508 rw_enter(&vd
->vdev_indirect_rwlock
, RW_WRITER
);
509 vdev_indirect_mapping_close(vd
->vdev_indirect_mapping
);
510 vd
->vdev_indirect_mapping
= sci
->sci_new_mapping
;
511 rw_exit(&vd
->vdev_indirect_rwlock
);
513 sci
->sci_new_mapping
= NULL
;
514 vdev_indirect_mapping_free(mos
, vic
->vic_mapping_object
, tx
);
515 vic
->vic_mapping_object
= scip
->scip_next_mapping_object
;
516 scip
->scip_next_mapping_object
= 0;
518 space_map_free_obj(mos
, scip
->scip_prev_obsolete_sm_object
, tx
);
519 spa_feature_decr(spa
, SPA_FEATURE_OBSOLETE_COUNTS
, tx
);
520 scip
->scip_prev_obsolete_sm_object
= 0;
524 VERIFY0(zap_remove(mos
, DMU_POOL_DIRECTORY_OBJECT
,
525 DMU_POOL_CONDENSING_INDIRECT
, tx
));
526 spa_condensing_indirect_destroy(spa
->spa_condensing_indirect
);
527 spa
->spa_condensing_indirect
= NULL
;
529 zfs_dbgmsg("finished condense of vdev %llu in txg %llu: "
530 "new mapping object %llu has %llu entries "
531 "(was %llu entries)",
532 vd
->vdev_id
, dmu_tx_get_txg(tx
), vic
->vic_mapping_object
,
533 new_count
, old_count
);
535 vdev_config_dirty(spa
->spa_root_vdev
);
539 * This sync task appends entries to the new mapping object.
542 spa_condense_indirect_commit_sync(void *arg
, dmu_tx_t
*tx
)
544 spa_condensing_indirect_t
*sci
= arg
;
545 uint64_t txg
= dmu_tx_get_txg(tx
);
546 ASSERTV(spa_t
*spa
= dmu_tx_pool(tx
)->dp_spa
);
548 ASSERT(dmu_tx_is_syncing(tx
));
549 ASSERT3P(sci
, ==, spa
->spa_condensing_indirect
);
551 vdev_indirect_mapping_add_entries(sci
->sci_new_mapping
,
552 &sci
->sci_new_mapping_entries
[txg
& TXG_MASK
], tx
);
553 ASSERT(list_is_empty(&sci
->sci_new_mapping_entries
[txg
& TXG_MASK
]));
557 * Open-context function to add one entry to the new mapping. The new
558 * entry will be remembered and written from syncing context.
561 spa_condense_indirect_commit_entry(spa_t
*spa
,
562 vdev_indirect_mapping_entry_phys_t
*vimep
, uint32_t count
)
564 spa_condensing_indirect_t
*sci
= spa
->spa_condensing_indirect
;
566 ASSERT3U(count
, <, DVA_GET_ASIZE(&vimep
->vimep_dst
));
568 dmu_tx_t
*tx
= dmu_tx_create_dd(spa_get_dsl(spa
)->dp_mos_dir
);
569 dmu_tx_hold_space(tx
, sizeof (*vimep
) + sizeof (count
));
570 VERIFY0(dmu_tx_assign(tx
, TXG_WAIT
));
571 int txgoff
= dmu_tx_get_txg(tx
) & TXG_MASK
;
574 * If we are the first entry committed this txg, kick off the sync
575 * task to write to the MOS on our behalf.
577 if (list_is_empty(&sci
->sci_new_mapping_entries
[txgoff
])) {
578 dsl_sync_task_nowait(dmu_tx_pool(tx
),
579 spa_condense_indirect_commit_sync
, sci
,
580 0, ZFS_SPACE_CHECK_NONE
, tx
);
583 vdev_indirect_mapping_entry_t
*vime
=
584 kmem_alloc(sizeof (*vime
), KM_SLEEP
);
585 vime
->vime_mapping
= *vimep
;
586 vime
->vime_obsolete_count
= count
;
587 list_insert_tail(&sci
->sci_new_mapping_entries
[txgoff
], vime
);
593 spa_condense_indirect_generate_new_mapping(vdev_t
*vd
,
594 uint32_t *obsolete_counts
, uint64_t start_index
, zthr_t
*zthr
)
596 spa_t
*spa
= vd
->vdev_spa
;
597 uint64_t mapi
= start_index
;
598 vdev_indirect_mapping_t
*old_mapping
= vd
->vdev_indirect_mapping
;
599 uint64_t old_num_entries
=
600 vdev_indirect_mapping_num_entries(old_mapping
);
602 ASSERT3P(vd
->vdev_ops
, ==, &vdev_indirect_ops
);
603 ASSERT3U(vd
->vdev_id
, ==, spa
->spa_condensing_indirect_phys
.scip_vdev
);
605 zfs_dbgmsg("starting condense of vdev %llu from index %llu",
606 (u_longlong_t
)vd
->vdev_id
,
609 while (mapi
< old_num_entries
) {
611 if (zthr_iscancelled(zthr
)) {
612 zfs_dbgmsg("pausing condense of vdev %llu "
613 "at index %llu", (u_longlong_t
)vd
->vdev_id
,
618 vdev_indirect_mapping_entry_phys_t
*entry
=
619 &old_mapping
->vim_entries
[mapi
];
620 uint64_t entry_size
= DVA_GET_ASIZE(&entry
->vimep_dst
);
621 ASSERT3U(obsolete_counts
[mapi
], <=, entry_size
);
622 if (obsolete_counts
[mapi
] < entry_size
) {
623 spa_condense_indirect_commit_entry(spa
, entry
,
624 obsolete_counts
[mapi
]);
627 * This delay may be requested for testing, debugging,
628 * or performance reasons.
630 hrtime_t now
= gethrtime();
631 hrtime_t sleep_until
= now
+ MSEC2NSEC(
632 zfs_condense_indirect_commit_entry_delay_ms
);
633 zfs_sleep_until(sleep_until
);
642 spa_condense_indirect_thread_check(void *arg
, zthr_t
*zthr
)
646 return (spa
->spa_condensing_indirect
!= NULL
);
651 spa_condense_indirect_thread(void *arg
, zthr_t
*zthr
)
656 ASSERT3P(spa
->spa_condensing_indirect
, !=, NULL
);
657 spa_config_enter(spa
, SCL_VDEV
, FTAG
, RW_READER
);
658 vd
= vdev_lookup_top(spa
, spa
->spa_condensing_indirect_phys
.scip_vdev
);
659 ASSERT3P(vd
, !=, NULL
);
660 spa_config_exit(spa
, SCL_VDEV
, FTAG
);
662 spa_condensing_indirect_t
*sci
= spa
->spa_condensing_indirect
;
663 spa_condensing_indirect_phys_t
*scip
=
664 &spa
->spa_condensing_indirect_phys
;
666 uint64_t start_index
;
667 vdev_indirect_mapping_t
*old_mapping
= vd
->vdev_indirect_mapping
;
668 space_map_t
*prev_obsolete_sm
= NULL
;
670 ASSERT3U(vd
->vdev_id
, ==, scip
->scip_vdev
);
671 ASSERT(scip
->scip_next_mapping_object
!= 0);
672 ASSERT(scip
->scip_prev_obsolete_sm_object
!= 0);
673 ASSERT3P(vd
->vdev_ops
, ==, &vdev_indirect_ops
);
675 for (int i
= 0; i
< TXG_SIZE
; i
++) {
677 * The list must start out empty in order for the
678 * _commit_sync() sync task to be properly registered
679 * on the first call to _commit_entry(); so it's wise
680 * to double check and ensure we actually are starting
683 ASSERT(list_is_empty(&sci
->sci_new_mapping_entries
[i
]));
686 VERIFY0(space_map_open(&prev_obsolete_sm
, spa
->spa_meta_objset
,
687 scip
->scip_prev_obsolete_sm_object
, 0, vd
->vdev_asize
, 0));
688 space_map_update(prev_obsolete_sm
);
689 counts
= vdev_indirect_mapping_load_obsolete_counts(old_mapping
);
690 if (prev_obsolete_sm
!= NULL
) {
691 vdev_indirect_mapping_load_obsolete_spacemap(old_mapping
,
692 counts
, prev_obsolete_sm
);
694 space_map_close(prev_obsolete_sm
);
697 * Generate new mapping. Determine what index to continue from
698 * based on the max offset that we've already written in the
701 uint64_t max_offset
=
702 vdev_indirect_mapping_max_offset(sci
->sci_new_mapping
);
703 if (max_offset
== 0) {
704 /* We haven't written anything to the new mapping yet. */
708 * Pick up from where we left off. _entry_for_offset()
709 * returns a pointer into the vim_entries array. If
710 * max_offset is greater than any of the mappings
711 * contained in the table NULL will be returned and
712 * that indicates we've exhausted our iteration of the
716 vdev_indirect_mapping_entry_phys_t
*entry
=
717 vdev_indirect_mapping_entry_for_offset_or_next(old_mapping
,
722 * We've already written the whole new mapping.
723 * This special value will cause us to skip the
724 * generate_new_mapping step and just do the sync
725 * task to complete the condense.
727 start_index
= UINT64_MAX
;
729 start_index
= entry
- old_mapping
->vim_entries
;
730 ASSERT3U(start_index
, <,
731 vdev_indirect_mapping_num_entries(old_mapping
));
735 spa_condense_indirect_generate_new_mapping(vd
, counts
,
738 vdev_indirect_mapping_free_obsolete_counts(old_mapping
, counts
);
741 * If the zthr has received a cancellation signal while running
742 * in generate_new_mapping() or at any point after that, then bail
743 * early. We don't want to complete the condense if the spa is
746 if (zthr_iscancelled(zthr
))
749 VERIFY0(dsl_sync_task(spa_name(spa
), NULL
,
750 spa_condense_indirect_complete_sync
, sci
, 0,
751 ZFS_SPACE_CHECK_EXTRA_RESERVED
));
757 * Sync task to begin the condensing process.
760 spa_condense_indirect_start_sync(vdev_t
*vd
, dmu_tx_t
*tx
)
762 spa_t
*spa
= vd
->vdev_spa
;
763 spa_condensing_indirect_phys_t
*scip
=
764 &spa
->spa_condensing_indirect_phys
;
766 ASSERT0(scip
->scip_next_mapping_object
);
767 ASSERT0(scip
->scip_prev_obsolete_sm_object
);
768 ASSERT0(scip
->scip_vdev
);
769 ASSERT(dmu_tx_is_syncing(tx
));
770 ASSERT3P(vd
->vdev_ops
, ==, &vdev_indirect_ops
);
771 ASSERT(spa_feature_is_active(spa
, SPA_FEATURE_OBSOLETE_COUNTS
));
772 ASSERT(vdev_indirect_mapping_num_entries(vd
->vdev_indirect_mapping
));
774 uint64_t obsolete_sm_obj
;
775 VERIFY0(vdev_obsolete_sm_object(vd
, &obsolete_sm_obj
));
776 ASSERT3U(obsolete_sm_obj
, !=, 0);
778 scip
->scip_vdev
= vd
->vdev_id
;
779 scip
->scip_next_mapping_object
=
780 vdev_indirect_mapping_alloc(spa
->spa_meta_objset
, tx
);
782 scip
->scip_prev_obsolete_sm_object
= obsolete_sm_obj
;
785 * We don't need to allocate a new space map object, since
786 * vdev_indirect_sync_obsolete will allocate one when needed.
788 space_map_close(vd
->vdev_obsolete_sm
);
789 vd
->vdev_obsolete_sm
= NULL
;
790 VERIFY0(zap_remove(spa
->spa_meta_objset
, vd
->vdev_top_zap
,
791 VDEV_TOP_ZAP_INDIRECT_OBSOLETE_SM
, tx
));
793 VERIFY0(zap_add(spa
->spa_dsl_pool
->dp_meta_objset
,
794 DMU_POOL_DIRECTORY_OBJECT
,
795 DMU_POOL_CONDENSING_INDIRECT
, sizeof (uint64_t),
796 sizeof (*scip
) / sizeof (uint64_t), scip
, tx
));
798 ASSERT3P(spa
->spa_condensing_indirect
, ==, NULL
);
799 spa
->spa_condensing_indirect
= spa_condensing_indirect_create(spa
);
801 zfs_dbgmsg("starting condense of vdev %llu in txg %llu: "
803 vd
->vdev_id
, dmu_tx_get_txg(tx
),
804 (u_longlong_t
)scip
->scip_prev_obsolete_sm_object
,
805 (u_longlong_t
)scip
->scip_next_mapping_object
);
807 zthr_wakeup(spa
->spa_condense_zthr
);
811 * Sync to the given vdev's obsolete space map any segments that are no longer
812 * referenced as of the given txg.
814 * If the obsolete space map doesn't exist yet, create and open it.
817 vdev_indirect_sync_obsolete(vdev_t
*vd
, dmu_tx_t
*tx
)
819 spa_t
*spa
= vd
->vdev_spa
;
820 ASSERTV(vdev_indirect_config_t
*vic
= &vd
->vdev_indirect_config
);
822 ASSERT3U(vic
->vic_mapping_object
, !=, 0);
823 ASSERT(range_tree_space(vd
->vdev_obsolete_segments
) > 0);
824 ASSERT(vd
->vdev_removing
|| vd
->vdev_ops
== &vdev_indirect_ops
);
825 ASSERT(spa_feature_is_enabled(spa
, SPA_FEATURE_OBSOLETE_COUNTS
));
827 uint64_t obsolete_sm_object
;
828 VERIFY0(vdev_obsolete_sm_object(vd
, &obsolete_sm_object
));
829 if (obsolete_sm_object
== 0) {
830 obsolete_sm_object
= space_map_alloc(spa
->spa_meta_objset
,
831 vdev_standard_sm_blksz
, tx
);
833 ASSERT(vd
->vdev_top_zap
!= 0);
834 VERIFY0(zap_add(vd
->vdev_spa
->spa_meta_objset
, vd
->vdev_top_zap
,
835 VDEV_TOP_ZAP_INDIRECT_OBSOLETE_SM
,
836 sizeof (obsolete_sm_object
), 1, &obsolete_sm_object
, tx
));
837 ASSERT0(vdev_obsolete_sm_object(vd
, &obsolete_sm_object
));
838 ASSERT3U(obsolete_sm_object
, !=, 0);
840 spa_feature_incr(spa
, SPA_FEATURE_OBSOLETE_COUNTS
, tx
);
841 VERIFY0(space_map_open(&vd
->vdev_obsolete_sm
,
842 spa
->spa_meta_objset
, obsolete_sm_object
,
843 0, vd
->vdev_asize
, 0));
844 space_map_update(vd
->vdev_obsolete_sm
);
847 ASSERT(vd
->vdev_obsolete_sm
!= NULL
);
848 ASSERT3U(obsolete_sm_object
, ==,
849 space_map_object(vd
->vdev_obsolete_sm
));
851 space_map_write(vd
->vdev_obsolete_sm
,
852 vd
->vdev_obsolete_segments
, SM_ALLOC
, SM_NO_VDEVID
, tx
);
853 space_map_update(vd
->vdev_obsolete_sm
);
854 range_tree_vacate(vd
->vdev_obsolete_segments
, NULL
, NULL
);
858 spa_condense_init(spa_t
*spa
)
860 int error
= zap_lookup(spa
->spa_meta_objset
,
861 DMU_POOL_DIRECTORY_OBJECT
,
862 DMU_POOL_CONDENSING_INDIRECT
, sizeof (uint64_t),
863 sizeof (spa
->spa_condensing_indirect_phys
) / sizeof (uint64_t),
864 &spa
->spa_condensing_indirect_phys
);
866 if (spa_writeable(spa
)) {
867 spa
->spa_condensing_indirect
=
868 spa_condensing_indirect_create(spa
);
871 } else if (error
== ENOENT
) {
879 spa_condense_fini(spa_t
*spa
)
881 if (spa
->spa_condensing_indirect
!= NULL
) {
882 spa_condensing_indirect_destroy(spa
->spa_condensing_indirect
);
883 spa
->spa_condensing_indirect
= NULL
;
888 spa_start_indirect_condensing_thread(spa_t
*spa
)
890 ASSERT3P(spa
->spa_condense_zthr
, ==, NULL
);
891 spa
->spa_condense_zthr
= zthr_create(spa_condense_indirect_thread_check
,
892 spa_condense_indirect_thread
, spa
);
896 * Gets the obsolete spacemap object from the vdev's ZAP. On success sm_obj
897 * will contain either the obsolete spacemap object or zero if none exists.
898 * All other errors are returned to the caller.
901 vdev_obsolete_sm_object(vdev_t
*vd
, uint64_t *sm_obj
)
903 ASSERT0(spa_config_held(vd
->vdev_spa
, SCL_ALL
, RW_WRITER
));
905 if (vd
->vdev_top_zap
== 0) {
910 int error
= zap_lookup(vd
->vdev_spa
->spa_meta_objset
, vd
->vdev_top_zap
,
911 VDEV_TOP_ZAP_INDIRECT_OBSOLETE_SM
, sizeof (sm_obj
), 1, sm_obj
);
912 if (error
== ENOENT
) {
921 * Gets the obsolete count are precise spacemap object from the vdev's ZAP.
922 * On success are_precise will be set to reflect if the counts are precise.
923 * All other errors are returned to the caller.
926 vdev_obsolete_counts_are_precise(vdev_t
*vd
, boolean_t
*are_precise
)
928 ASSERT0(spa_config_held(vd
->vdev_spa
, SCL_ALL
, RW_WRITER
));
930 if (vd
->vdev_top_zap
== 0) {
931 *are_precise
= B_FALSE
;
936 int error
= zap_lookup(vd
->vdev_spa
->spa_meta_objset
, vd
->vdev_top_zap
,
937 VDEV_TOP_ZAP_OBSOLETE_COUNTS_ARE_PRECISE
, sizeof (val
), 1, &val
);
939 *are_precise
= (val
!= 0);
940 } else if (error
== ENOENT
) {
941 *are_precise
= B_FALSE
;
950 vdev_indirect_close(vdev_t
*vd
)
956 vdev_indirect_open(vdev_t
*vd
, uint64_t *psize
, uint64_t *max_psize
,
959 *psize
= *max_psize
= vd
->vdev_asize
+
960 VDEV_LABEL_START_SIZE
+ VDEV_LABEL_END_SIZE
;
961 *ashift
= vd
->vdev_ashift
;
965 typedef struct remap_segment
{
969 uint64_t rs_split_offset
;
974 rs_alloc(vdev_t
*vd
, uint64_t offset
, uint64_t asize
, uint64_t split_offset
)
976 remap_segment_t
*rs
= kmem_alloc(sizeof (remap_segment_t
), KM_SLEEP
);
978 rs
->rs_offset
= offset
;
979 rs
->rs_asize
= asize
;
980 rs
->rs_split_offset
= split_offset
;
985 * Given an indirect vdev and an extent on that vdev, it duplicates the
986 * physical entries of the indirect mapping that correspond to the extent
987 * to a new array and returns a pointer to it. In addition, copied_entries
988 * is populated with the number of mapping entries that were duplicated.
990 * Note that the function assumes that the caller holds vdev_indirect_rwlock.
991 * This ensures that the mapping won't change due to condensing as we
992 * copy over its contents.
994 * Finally, since we are doing an allocation, it is up to the caller to
995 * free the array allocated in this function.
997 vdev_indirect_mapping_entry_phys_t
*
998 vdev_indirect_mapping_duplicate_adjacent_entries(vdev_t
*vd
, uint64_t offset
,
999 uint64_t asize
, uint64_t *copied_entries
)
1001 vdev_indirect_mapping_entry_phys_t
*duplicate_mappings
= NULL
;
1002 vdev_indirect_mapping_t
*vim
= vd
->vdev_indirect_mapping
;
1003 uint64_t entries
= 0;
1005 ASSERT(RW_READ_HELD(&vd
->vdev_indirect_rwlock
));
1007 vdev_indirect_mapping_entry_phys_t
*first_mapping
=
1008 vdev_indirect_mapping_entry_for_offset(vim
, offset
);
1009 ASSERT3P(first_mapping
, !=, NULL
);
1011 vdev_indirect_mapping_entry_phys_t
*m
= first_mapping
;
1013 uint64_t size
= DVA_GET_ASIZE(&m
->vimep_dst
);
1015 ASSERT3U(offset
, >=, DVA_MAPPING_GET_SRC_OFFSET(m
));
1016 ASSERT3U(offset
, <, DVA_MAPPING_GET_SRC_OFFSET(m
) + size
);
1018 uint64_t inner_offset
= offset
- DVA_MAPPING_GET_SRC_OFFSET(m
);
1019 uint64_t inner_size
= MIN(asize
, size
- inner_offset
);
1021 offset
+= inner_size
;
1022 asize
-= inner_size
;
1027 size_t copy_length
= entries
* sizeof (*first_mapping
);
1028 duplicate_mappings
= kmem_alloc(copy_length
, KM_SLEEP
);
1029 bcopy(first_mapping
, duplicate_mappings
, copy_length
);
1030 *copied_entries
= entries
;
1032 return (duplicate_mappings
);
1036 * Goes through the relevant indirect mappings until it hits a concrete vdev
1037 * and issues the callback. On the way to the concrete vdev, if any other
1038 * indirect vdevs are encountered, then the callback will also be called on
1039 * each of those indirect vdevs. For example, if the segment is mapped to
1040 * segment A on indirect vdev 1, and then segment A on indirect vdev 1 is
1041 * mapped to segment B on concrete vdev 2, then the callback will be called on
1042 * both vdev 1 and vdev 2.
1044 * While the callback passed to vdev_indirect_remap() is called on every vdev
1045 * the function encounters, certain callbacks only care about concrete vdevs.
1046 * These types of callbacks should return immediately and explicitly when they
1047 * are called on an indirect vdev.
1049 * Because there is a possibility that a DVA section in the indirect device
1050 * has been split into multiple sections in our mapping, we keep track
1051 * of the relevant contiguous segments of the new location (remap_segment_t)
1052 * in a stack. This way we can call the callback for each of the new sections
1053 * created by a single section of the indirect device. Note though, that in
1054 * this scenario the callbacks in each split block won't occur in-order in
1055 * terms of offset, so callers should not make any assumptions about that.
1057 * For callbacks that don't handle split blocks and immediately return when
1058 * they encounter them (as is the case for remap_blkptr_cb), the caller can
1059 * assume that its callback will be applied from the first indirect vdev
1060 * encountered to the last one and then the concrete vdev, in that order.
1063 vdev_indirect_remap(vdev_t
*vd
, uint64_t offset
, uint64_t asize
,
1064 void (*func
)(uint64_t, vdev_t
*, uint64_t, uint64_t, void *), void *arg
)
1067 spa_t
*spa
= vd
->vdev_spa
;
1069 list_create(&stack
, sizeof (remap_segment_t
),
1070 offsetof(remap_segment_t
, rs_node
));
1072 for (remap_segment_t
*rs
= rs_alloc(vd
, offset
, asize
, 0);
1073 rs
!= NULL
; rs
= list_remove_head(&stack
)) {
1074 vdev_t
*v
= rs
->rs_vd
;
1075 uint64_t num_entries
= 0;
1077 ASSERT(spa_config_held(spa
, SCL_ALL
, RW_READER
) != 0);
1078 ASSERT(rs
->rs_asize
> 0);
1081 * Note: As this function can be called from open context
1082 * (e.g. zio_read()), we need the following rwlock to
1083 * prevent the mapping from being changed by condensing.
1085 * So we grab the lock and we make a copy of the entries
1086 * that are relevant to the extent that we are working on.
1087 * Once that is done, we drop the lock and iterate over
1088 * our copy of the mapping. Once we are done with the with
1089 * the remap segment and we free it, we also free our copy
1090 * of the indirect mapping entries that are relevant to it.
1092 * This way we don't need to wait until the function is
1093 * finished with a segment, to condense it. In addition, we
1094 * don't need a recursive rwlock for the case that a call to
1095 * vdev_indirect_remap() needs to call itself (through the
1096 * codepath of its callback) for the same vdev in the middle
1099 rw_enter(&v
->vdev_indirect_rwlock
, RW_READER
);
1100 ASSERT3P(v
->vdev_indirect_mapping
, !=, NULL
);
1102 vdev_indirect_mapping_entry_phys_t
*mapping
=
1103 vdev_indirect_mapping_duplicate_adjacent_entries(v
,
1104 rs
->rs_offset
, rs
->rs_asize
, &num_entries
);
1105 ASSERT3P(mapping
, !=, NULL
);
1106 ASSERT3U(num_entries
, >, 0);
1107 rw_exit(&v
->vdev_indirect_rwlock
);
1109 for (uint64_t i
= 0; i
< num_entries
; i
++) {
1111 * Note: the vdev_indirect_mapping can not change
1112 * while we are running. It only changes while the
1113 * removal is in progress, and then only from syncing
1114 * context. While a removal is in progress, this
1115 * function is only called for frees, which also only
1116 * happen from syncing context.
1118 vdev_indirect_mapping_entry_phys_t
*m
= &mapping
[i
];
1120 ASSERT3P(m
, !=, NULL
);
1121 ASSERT3U(rs
->rs_asize
, >, 0);
1123 uint64_t size
= DVA_GET_ASIZE(&m
->vimep_dst
);
1124 uint64_t dst_offset
= DVA_GET_OFFSET(&m
->vimep_dst
);
1125 uint64_t dst_vdev
= DVA_GET_VDEV(&m
->vimep_dst
);
1127 ASSERT3U(rs
->rs_offset
, >=,
1128 DVA_MAPPING_GET_SRC_OFFSET(m
));
1129 ASSERT3U(rs
->rs_offset
, <,
1130 DVA_MAPPING_GET_SRC_OFFSET(m
) + size
);
1131 ASSERT3U(dst_vdev
, !=, v
->vdev_id
);
1133 uint64_t inner_offset
= rs
->rs_offset
-
1134 DVA_MAPPING_GET_SRC_OFFSET(m
);
1135 uint64_t inner_size
=
1136 MIN(rs
->rs_asize
, size
- inner_offset
);
1138 vdev_t
*dst_v
= vdev_lookup_top(spa
, dst_vdev
);
1139 ASSERT3P(dst_v
, !=, NULL
);
1141 if (dst_v
->vdev_ops
== &vdev_indirect_ops
) {
1142 list_insert_head(&stack
,
1143 rs_alloc(dst_v
, dst_offset
+ inner_offset
,
1144 inner_size
, rs
->rs_split_offset
));
1148 if ((zfs_flags
& ZFS_DEBUG_INDIRECT_REMAP
) &&
1149 IS_P2ALIGNED(inner_size
, 2 * SPA_MINBLOCKSIZE
)) {
1151 * Note: This clause exists only solely for
1152 * testing purposes. We use it to ensure that
1153 * split blocks work and that the callbacks
1154 * using them yield the same result if issued
1157 uint64_t inner_half
= inner_size
/ 2;
1159 func(rs
->rs_split_offset
+ inner_half
, dst_v
,
1160 dst_offset
+ inner_offset
+ inner_half
,
1163 func(rs
->rs_split_offset
, dst_v
,
1164 dst_offset
+ inner_offset
,
1167 func(rs
->rs_split_offset
, dst_v
,
1168 dst_offset
+ inner_offset
,
1172 rs
->rs_offset
+= inner_size
;
1173 rs
->rs_asize
-= inner_size
;
1174 rs
->rs_split_offset
+= inner_size
;
1176 VERIFY0(rs
->rs_asize
);
1178 kmem_free(mapping
, num_entries
* sizeof (*mapping
));
1179 kmem_free(rs
, sizeof (remap_segment_t
));
1181 list_destroy(&stack
);
1185 vdev_indirect_child_io_done(zio_t
*zio
)
1187 zio_t
*pio
= zio
->io_private
;
1189 mutex_enter(&pio
->io_lock
);
1190 pio
->io_error
= zio_worst_error(pio
->io_error
, zio
->io_error
);
1191 mutex_exit(&pio
->io_lock
);
1193 abd_put(zio
->io_abd
);
1197 * This is a callback for vdev_indirect_remap() which allocates an
1198 * indirect_split_t for each split segment and adds it to iv_splits.
1201 vdev_indirect_gather_splits(uint64_t split_offset
, vdev_t
*vd
, uint64_t offset
,
1202 uint64_t size
, void *arg
)
1205 indirect_vsd_t
*iv
= zio
->io_vsd
;
1207 ASSERT3P(vd
, !=, NULL
);
1209 if (vd
->vdev_ops
== &vdev_indirect_ops
)
1213 if (vd
->vdev_ops
== &vdev_mirror_ops
)
1214 n
= vd
->vdev_children
;
1216 indirect_split_t
*is
=
1217 kmem_zalloc(offsetof(indirect_split_t
, is_child
[n
]), KM_SLEEP
);
1219 is
->is_children
= n
;
1221 is
->is_split_offset
= split_offset
;
1222 is
->is_target_offset
= offset
;
1224 list_create(&is
->is_unique_child
, sizeof (indirect_child_t
),
1225 offsetof(indirect_child_t
, ic_node
));
1228 * Note that we only consider multiple copies of the data for
1229 * *mirror* vdevs. We don't for "replacing" or "spare" vdevs, even
1230 * though they use the same ops as mirror, because there's only one
1231 * "good" copy under the replacing/spare.
1233 if (vd
->vdev_ops
== &vdev_mirror_ops
) {
1234 for (int i
= 0; i
< n
; i
++) {
1235 is
->is_child
[i
].ic_vdev
= vd
->vdev_child
[i
];
1236 list_link_init(&is
->is_child
[i
].ic_node
);
1239 is
->is_child
[0].ic_vdev
= vd
;
1242 list_insert_tail(&iv
->iv_splits
, is
);
1246 vdev_indirect_read_split_done(zio_t
*zio
)
1248 indirect_child_t
*ic
= zio
->io_private
;
1250 if (zio
->io_error
!= 0) {
1252 * Clear ic_data to indicate that we do not have data for this
1255 abd_free(ic
->ic_data
);
1261 * Issue reads for all copies (mirror children) of all splits.
1264 vdev_indirect_read_all(zio_t
*zio
)
1266 indirect_vsd_t
*iv
= zio
->io_vsd
;
1268 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1269 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1270 for (int i
= 0; i
< is
->is_children
; i
++) {
1271 indirect_child_t
*ic
= &is
->is_child
[i
];
1273 if (!vdev_readable(ic
->ic_vdev
))
1277 * Note, we may read from a child whose DTL
1278 * indicates that the data may not be present here.
1279 * While this might result in a few i/os that will
1280 * likely return incorrect data, it simplifies the
1281 * code since we can treat scrub and resilver
1282 * identically. (The incorrect data will be
1283 * detected and ignored when we verify the
1287 ic
->ic_data
= abd_alloc_sametype(zio
->io_abd
,
1289 ic
->ic_duplicate
= NULL
;
1291 zio_nowait(zio_vdev_child_io(zio
, NULL
,
1292 ic
->ic_vdev
, is
->is_target_offset
, ic
->ic_data
,
1293 is
->is_size
, zio
->io_type
, zio
->io_priority
, 0,
1294 vdev_indirect_read_split_done
, ic
));
1297 iv
->iv_reconstruct
= B_TRUE
;
1301 vdev_indirect_io_start(zio_t
*zio
)
1303 ASSERTV(spa_t
*spa
= zio
->io_spa
);
1304 indirect_vsd_t
*iv
= kmem_zalloc(sizeof (*iv
), KM_SLEEP
);
1305 list_create(&iv
->iv_splits
,
1306 sizeof (indirect_split_t
), offsetof(indirect_split_t
, is_node
));
1309 zio
->io_vsd_ops
= &vdev_indirect_vsd_ops
;
1311 ASSERT(spa_config_held(spa
, SCL_ALL
, RW_READER
) != 0);
1312 if (zio
->io_type
!= ZIO_TYPE_READ
) {
1313 ASSERT3U(zio
->io_type
, ==, ZIO_TYPE_WRITE
);
1315 * Note: this code can handle other kinds of writes,
1316 * but we don't expect them.
1318 ASSERT((zio
->io_flags
& (ZIO_FLAG_SELF_HEAL
|
1319 ZIO_FLAG_RESILVER
| ZIO_FLAG_INDUCE_DAMAGE
)) != 0);
1322 vdev_indirect_remap(zio
->io_vd
, zio
->io_offset
, zio
->io_size
,
1323 vdev_indirect_gather_splits
, zio
);
1325 indirect_split_t
*first
= list_head(&iv
->iv_splits
);
1326 if (first
->is_size
== zio
->io_size
) {
1328 * This is not a split block; we are pointing to the entire
1329 * data, which will checksum the same as the original data.
1330 * Pass the BP down so that the child i/o can verify the
1331 * checksum, and try a different location if available
1332 * (e.g. on a mirror).
1334 * While this special case could be handled the same as the
1335 * general (split block) case, doing it this way ensures
1336 * that the vast majority of blocks on indirect vdevs
1337 * (which are not split) are handled identically to blocks
1338 * on non-indirect vdevs. This allows us to be less strict
1339 * about performance in the general (but rare) case.
1341 ASSERT0(first
->is_split_offset
);
1342 ASSERT3P(list_next(&iv
->iv_splits
, first
), ==, NULL
);
1343 zio_nowait(zio_vdev_child_io(zio
, zio
->io_bp
,
1344 first
->is_vdev
, first
->is_target_offset
,
1345 abd_get_offset(zio
->io_abd
, 0),
1346 zio
->io_size
, zio
->io_type
, zio
->io_priority
, 0,
1347 vdev_indirect_child_io_done
, zio
));
1349 iv
->iv_split_block
= B_TRUE
;
1350 if (zio
->io_flags
& (ZIO_FLAG_SCRUB
| ZIO_FLAG_RESILVER
)) {
1352 * Read all copies. Note that for simplicity,
1353 * we don't bother consulting the DTL in the
1356 vdev_indirect_read_all(zio
);
1359 * Read one copy of each split segment, from the
1360 * top-level vdev. Since we don't know the
1361 * checksum of each split individually, the child
1362 * zio can't ensure that we get the right data.
1363 * E.g. if it's a mirror, it will just read from a
1364 * random (healthy) leaf vdev. We have to verify
1365 * the checksum in vdev_indirect_io_done().
1367 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1368 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1369 zio_nowait(zio_vdev_child_io(zio
, NULL
,
1370 is
->is_vdev
, is
->is_target_offset
,
1371 abd_get_offset(zio
->io_abd
,
1372 is
->is_split_offset
), is
->is_size
,
1373 zio
->io_type
, zio
->io_priority
, 0,
1374 vdev_indirect_child_io_done
, zio
));
1384 * Report a checksum error for a child.
1387 vdev_indirect_checksum_error(zio_t
*zio
,
1388 indirect_split_t
*is
, indirect_child_t
*ic
)
1390 vdev_t
*vd
= ic
->ic_vdev
;
1392 if (zio
->io_flags
& ZIO_FLAG_SPECULATIVE
)
1395 mutex_enter(&vd
->vdev_stat_lock
);
1396 vd
->vdev_stat
.vs_checksum_errors
++;
1397 mutex_exit(&vd
->vdev_stat_lock
);
1399 zio_bad_cksum_t zbc
= {{{ 0 }}};
1400 abd_t
*bad_abd
= ic
->ic_data
;
1401 abd_t
*good_abd
= is
->is_good_child
->ic_data
;
1402 zfs_ereport_post_checksum(zio
->io_spa
, vd
, NULL
, zio
,
1403 is
->is_target_offset
, is
->is_size
, good_abd
, bad_abd
, &zbc
);
1407 * Issue repair i/os for any incorrect copies. We do this by comparing
1408 * each split segment's correct data (is_good_child's ic_data) with each
1409 * other copy of the data. If they differ, then we overwrite the bad data
1410 * with the good copy. Note that we do this without regard for the DTL's,
1411 * which simplifies this code and also issues the optimal number of writes
1412 * (based on which copies actually read bad data, as opposed to which we
1413 * think might be wrong). For the same reason, we always use
1414 * ZIO_FLAG_SELF_HEAL, to bypass the DTL check in zio_vdev_io_start().
1417 vdev_indirect_repair(zio_t
*zio
)
1419 indirect_vsd_t
*iv
= zio
->io_vsd
;
1421 enum zio_flag flags
= ZIO_FLAG_IO_REPAIR
;
1423 if (!(zio
->io_flags
& (ZIO_FLAG_SCRUB
| ZIO_FLAG_RESILVER
)))
1424 flags
|= ZIO_FLAG_SELF_HEAL
;
1426 if (!spa_writeable(zio
->io_spa
))
1429 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1430 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1431 for (int c
= 0; c
< is
->is_children
; c
++) {
1432 indirect_child_t
*ic
= &is
->is_child
[c
];
1433 if (ic
== is
->is_good_child
)
1435 if (ic
->ic_data
== NULL
)
1437 if (ic
->ic_duplicate
== is
->is_good_child
)
1440 zio_nowait(zio_vdev_child_io(zio
, NULL
,
1441 ic
->ic_vdev
, is
->is_target_offset
,
1442 is
->is_good_child
->ic_data
, is
->is_size
,
1443 ZIO_TYPE_WRITE
, ZIO_PRIORITY_ASYNC_WRITE
,
1444 ZIO_FLAG_IO_REPAIR
| ZIO_FLAG_SELF_HEAL
,
1447 vdev_indirect_checksum_error(zio
, is
, ic
);
1453 * Report checksum errors on all children that we read from.
1456 vdev_indirect_all_checksum_errors(zio_t
*zio
)
1458 indirect_vsd_t
*iv
= zio
->io_vsd
;
1460 if (zio
->io_flags
& ZIO_FLAG_SPECULATIVE
)
1463 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1464 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1465 for (int c
= 0; c
< is
->is_children
; c
++) {
1466 indirect_child_t
*ic
= &is
->is_child
[c
];
1468 if (ic
->ic_data
== NULL
)
1471 vdev_t
*vd
= ic
->ic_vdev
;
1473 mutex_enter(&vd
->vdev_stat_lock
);
1474 vd
->vdev_stat
.vs_checksum_errors
++;
1475 mutex_exit(&vd
->vdev_stat_lock
);
1477 zfs_ereport_post_checksum(zio
->io_spa
, vd
, NULL
, zio
,
1478 is
->is_target_offset
, is
->is_size
,
1485 * Copy data from all the splits to a main zio then validate the checksum.
1486 * If then checksum is successfully validated return success.
1489 vdev_indirect_splits_checksum_validate(indirect_vsd_t
*iv
, zio_t
*zio
)
1491 zio_bad_cksum_t zbc
;
1493 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1494 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1496 ASSERT3P(is
->is_good_child
->ic_data
, !=, NULL
);
1497 ASSERT3P(is
->is_good_child
->ic_duplicate
, ==, NULL
);
1499 abd_copy_off(zio
->io_abd
, is
->is_good_child
->ic_data
,
1500 is
->is_split_offset
, 0, is
->is_size
);
1503 return (zio_checksum_error(zio
, &zbc
));
1507 * There are relatively few possible combinations making it feasible to
1508 * deterministically check them all. We do this by setting the good_child
1509 * to the next unique split version. If we reach the end of the list then
1510 * "carry over" to the next unique split version (like counting in base
1511 * is_unique_children, but each digit can have a different base).
1514 vdev_indirect_splits_enumerate_all(indirect_vsd_t
*iv
, zio_t
*zio
)
1516 boolean_t more
= B_TRUE
;
1518 iv
->iv_attempts
= 0;
1520 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1521 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
))
1522 is
->is_good_child
= list_head(&is
->is_unique_child
);
1524 while (more
== B_TRUE
) {
1528 if (vdev_indirect_splits_checksum_validate(iv
, zio
) == 0)
1531 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1532 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1533 is
->is_good_child
= list_next(&is
->is_unique_child
,
1535 if (is
->is_good_child
!= NULL
) {
1540 is
->is_good_child
= list_head(&is
->is_unique_child
);
1544 ASSERT3S(iv
->iv_attempts
, <=, iv
->iv_unique_combinations
);
1546 return (SET_ERROR(ECKSUM
));
1550 * There are too many combinations to try all of them in a reasonable amount
1551 * of time. So try a fixed number of random combinations from the unique
1552 * split versions, after which we'll consider the block unrecoverable.
1555 vdev_indirect_splits_enumerate_randomly(indirect_vsd_t
*iv
, zio_t
*zio
)
1557 iv
->iv_attempts
= 0;
1559 while (iv
->iv_attempts
< iv
->iv_attempts_max
) {
1562 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1563 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1564 indirect_child_t
*ic
= list_head(&is
->is_unique_child
);
1565 int children
= is
->is_unique_children
;
1567 for (int i
= spa_get_random(children
); i
> 0; i
--)
1568 ic
= list_next(&is
->is_unique_child
, ic
);
1570 ASSERT3P(ic
, !=, NULL
);
1571 is
->is_good_child
= ic
;
1574 if (vdev_indirect_splits_checksum_validate(iv
, zio
) == 0)
1578 return (SET_ERROR(ECKSUM
));
1582 * This is a validation function for reconstruction. It randomly selects
1583 * a good combination, if one can be found, and then it intentionally
1584 * damages all other segment copes by zeroing them. This forces the
1585 * reconstruction algorithm to locate the one remaining known good copy.
1588 vdev_indirect_splits_damage(indirect_vsd_t
*iv
, zio_t
*zio
)
1590 /* Presume all the copies are unique for initial selection. */
1591 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1592 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1593 is
->is_unique_children
= 0;
1595 for (int i
= 0; i
< is
->is_children
; i
++) {
1596 indirect_child_t
*ic
= &is
->is_child
[i
];
1597 if (ic
->ic_data
!= NULL
) {
1598 is
->is_unique_children
++;
1599 list_insert_tail(&is
->is_unique_child
, ic
);
1605 * Set each is_good_child to a randomly-selected child which
1606 * is known to contain validated data.
1608 int error
= vdev_indirect_splits_enumerate_randomly(iv
, zio
);
1613 * Damage all but the known good copy by zeroing it. This will
1614 * result in two or less unique copies per indirect_child_t.
1615 * Both may need to be checked in order to reconstruct the block.
1616 * Set iv->iv_attempts_max such that all unique combinations will
1617 * enumerated, but limit the damage to at most 12 indirect splits.
1619 iv
->iv_attempts_max
= 1;
1621 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1622 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1623 for (int c
= 0; c
< is
->is_children
; c
++) {
1624 indirect_child_t
*ic
= &is
->is_child
[c
];
1626 if (ic
== is
->is_good_child
)
1628 if (ic
->ic_data
== NULL
)
1631 abd_zero(ic
->ic_data
, ic
->ic_data
->abd_size
);
1634 iv
->iv_attempts_max
*= 2;
1635 if (iv
->iv_attempts_max
>= (1ULL << 12)) {
1636 iv
->iv_attempts_max
= UINT64_MAX
;
1642 /* Empty the unique children lists so they can be reconstructed. */
1643 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1644 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1645 indirect_child_t
*ic
;
1646 while ((ic
= list_head(&is
->is_unique_child
)) != NULL
)
1647 list_remove(&is
->is_unique_child
, ic
);
1649 is
->is_unique_children
= 0;
1656 * This function is called when we have read all copies of the data and need
1657 * to try to find a combination of copies that gives us the right checksum.
1659 * If we pointed to any mirror vdevs, this effectively does the job of the
1660 * mirror. The mirror vdev code can't do its own job because we don't know
1661 * the checksum of each split segment individually.
1663 * We have to try every unique combination of copies of split segments, until
1664 * we find one that checksums correctly. Duplicate segment copies are first
1665 * identified and latter skipped during reconstruction. This optimization
1666 * reduces the search space and ensures that of the remaining combinations
1667 * at most one is correct.
1669 * When the total number of combinations is small they can all be checked.
1670 * For example, if we have 3 segments in the split, and each points to a
1671 * 2-way mirror with unique copies, we will have the following pieces of data:
1675 * ======|=====================
1676 * A | data_A_0 data_A_1
1677 * B | data_B_0 data_B_1
1678 * C | data_C_0 data_C_1
1680 * We will try the following (mirror children)^(number of splits) (2^3=8)
1681 * combinations, which is similar to bitwise-little-endian counting in
1682 * binary. In general each "digit" corresponds to a split segment, and the
1683 * base of each digit is is_children, which can be different for each
1686 * "low bit" "high bit"
1688 * data_A_0 data_B_0 data_C_0
1689 * data_A_1 data_B_0 data_C_0
1690 * data_A_0 data_B_1 data_C_0
1691 * data_A_1 data_B_1 data_C_0
1692 * data_A_0 data_B_0 data_C_1
1693 * data_A_1 data_B_0 data_C_1
1694 * data_A_0 data_B_1 data_C_1
1695 * data_A_1 data_B_1 data_C_1
1697 * Note that the split segments may be on the same or different top-level
1698 * vdevs. In either case, we may need to try lots of combinations (see
1699 * zfs_reconstruct_indirect_combinations_max). This ensures that if a mirror
1700 * has small silent errors on all of its children, we can still reconstruct
1701 * the correct data, as long as those errors are at sufficiently-separated
1702 * offsets (specifically, separated by the largest block size - default of
1703 * 128KB, but up to 16MB).
1706 vdev_indirect_reconstruct_io_done(zio_t
*zio
)
1708 indirect_vsd_t
*iv
= zio
->io_vsd
;
1709 boolean_t known_good
= B_FALSE
;
1712 iv
->iv_unique_combinations
= 1;
1713 iv
->iv_attempts_max
= UINT64_MAX
;
1715 if (zfs_reconstruct_indirect_combinations_max
> 0)
1716 iv
->iv_attempts_max
= zfs_reconstruct_indirect_combinations_max
;
1719 * If nonzero, every 1/x blocks will be damaged, in order to validate
1720 * reconstruction when there are split segments with damaged copies.
1721 * Known_good will be TRUE when reconstruction is known to be possible.
1723 if (zfs_reconstruct_indirect_damage_fraction
!= 0 &&
1724 spa_get_random(zfs_reconstruct_indirect_damage_fraction
) == 0)
1725 known_good
= (vdev_indirect_splits_damage(iv
, zio
) == 0);
1728 * Determine the unique children for a split segment and add them
1729 * to the is_unique_child list. By restricting reconstruction
1730 * to these children, only unique combinations will be considered.
1731 * This can vastly reduce the search space when there are a large
1732 * number of indirect splits.
1734 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1735 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1736 is
->is_unique_children
= 0;
1738 for (int i
= 0; i
< is
->is_children
; i
++) {
1739 indirect_child_t
*ic_i
= &is
->is_child
[i
];
1741 if (ic_i
->ic_data
== NULL
||
1742 ic_i
->ic_duplicate
!= NULL
)
1745 for (int j
= i
+ 1; j
< is
->is_children
; j
++) {
1746 indirect_child_t
*ic_j
= &is
->is_child
[j
];
1748 if (ic_j
->ic_data
== NULL
||
1749 ic_j
->ic_duplicate
!= NULL
)
1752 if (abd_cmp(ic_i
->ic_data
, ic_j
->ic_data
) == 0)
1753 ic_j
->ic_duplicate
= ic_i
;
1756 is
->is_unique_children
++;
1757 list_insert_tail(&is
->is_unique_child
, ic_i
);
1760 /* Reconstruction is impossible, no valid children */
1761 EQUIV(list_is_empty(&is
->is_unique_child
),
1762 is
->is_unique_children
== 0);
1763 if (list_is_empty(&is
->is_unique_child
)) {
1764 zio
->io_error
= EIO
;
1765 vdev_indirect_all_checksum_errors(zio
);
1766 zio_checksum_verified(zio
);
1770 iv
->iv_unique_combinations
*= is
->is_unique_children
;
1773 if (iv
->iv_unique_combinations
<= iv
->iv_attempts_max
)
1774 error
= vdev_indirect_splits_enumerate_all(iv
, zio
);
1776 error
= vdev_indirect_splits_enumerate_randomly(iv
, zio
);
1779 /* All attempted combinations failed. */
1780 ASSERT3B(known_good
, ==, B_FALSE
);
1781 zio
->io_error
= error
;
1782 vdev_indirect_all_checksum_errors(zio
);
1785 * The checksum has been successfully validated. Issue
1786 * repair I/Os to any copies of splits which don't match
1787 * the validated version.
1789 ASSERT0(vdev_indirect_splits_checksum_validate(iv
, zio
));
1790 vdev_indirect_repair(zio
);
1791 zio_checksum_verified(zio
);
1796 vdev_indirect_io_done(zio_t
*zio
)
1798 indirect_vsd_t
*iv
= zio
->io_vsd
;
1800 if (iv
->iv_reconstruct
) {
1802 * We have read all copies of the data (e.g. from mirrors),
1803 * either because this was a scrub/resilver, or because the
1804 * one-copy read didn't checksum correctly.
1806 vdev_indirect_reconstruct_io_done(zio
);
1810 if (!iv
->iv_split_block
) {
1812 * This was not a split block, so we passed the BP down,
1813 * and the checksum was handled by the (one) child zio.
1818 zio_bad_cksum_t zbc
;
1819 int ret
= zio_checksum_error(zio
, &zbc
);
1821 zio_checksum_verified(zio
);
1826 * The checksum didn't match. Read all copies of all splits, and
1827 * then we will try to reconstruct. The next time
1828 * vdev_indirect_io_done() is called, iv_reconstruct will be set.
1830 vdev_indirect_read_all(zio
);
1832 zio_vdev_io_redone(zio
);
1835 vdev_ops_t vdev_indirect_ops
= {
1837 vdev_indirect_close
,
1839 vdev_indirect_io_start
,
1840 vdev_indirect_io_done
,
1845 vdev_indirect_remap
,
1846 VDEV_TYPE_INDIRECT
, /* name of this vdev type */
1847 B_FALSE
/* leaf vdev */
1850 #if defined(_KERNEL)
1851 EXPORT_SYMBOL(rs_alloc
);
1852 EXPORT_SYMBOL(spa_condense_fini
);
1853 EXPORT_SYMBOL(spa_start_indirect_condensing_thread
);
1854 EXPORT_SYMBOL(spa_condense_indirect_start_sync
);
1855 EXPORT_SYMBOL(spa_condense_init
);
1856 EXPORT_SYMBOL(spa_vdev_indirect_mark_obsolete
);
1857 EXPORT_SYMBOL(vdev_indirect_mark_obsolete
);
1858 EXPORT_SYMBOL(vdev_indirect_should_condense
);
1859 EXPORT_SYMBOL(vdev_indirect_sync_obsolete
);
1860 EXPORT_SYMBOL(vdev_obsolete_counts_are_precise
);
1861 EXPORT_SYMBOL(vdev_obsolete_sm_object
);
1863 module_param(zfs_condense_indirect_vdevs_enable
, int, 0644);
1864 MODULE_PARM_DESC(zfs_condense_indirect_vdevs_enable
,
1865 "Whether to attempt condensing indirect vdev mappings");
1868 module_param(zfs_condense_min_mapping_bytes
, ulong
, 0644);
1869 MODULE_PARM_DESC(zfs_condense_min_mapping_bytes
,
1870 "Minimum size of vdev mapping to condense");
1873 module_param(zfs_condense_max_obsolete_bytes
, ulong
, 0644);
1874 MODULE_PARM_DESC(zfs_condense_max_obsolete_bytes
,
1875 "Minimum size obsolete spacemap to attempt condensing");
1877 module_param(zfs_condense_indirect_commit_entry_delay_ms
, int, 0644);
1878 MODULE_PARM_DESC(zfs_condense_indirect_commit_entry_delay_ms
,
1879 "Delay while condensing vdev mapping");
1881 module_param(zfs_reconstruct_indirect_combinations_max
, int, 0644);
1882 MODULE_PARM_DESC(zfs_reconstruct_indirect_combinations_max
,
1883 "Maximum number of combinations when reconstructing split segments");