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66 * keep track of how much of each mapping entry is obsolete.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
= 100;
219 * The indirect_child_t represents the vdev that we will read from, when we
220 * need to read all copies of the data (e.g. for scrub or reconstruction).
221 * For plain (non-mirror) top-level vdevs (i.e. is_vdev is not a mirror),
222 * ic_vdev is the same as is_vdev. However, for mirror top-level vdevs,
223 * ic_vdev is a child of the mirror.
225 typedef struct indirect_child
{
230 * ic_duplicate is -1 when the ic_data contents are unique, when it
231 * is determined to be a duplicate it refers to the primary child.
237 * The indirect_split_t represents one mapped segment of an i/o to the
238 * indirect vdev. For non-split (contiguously-mapped) blocks, there will be
239 * only one indirect_split_t, with is_split_offset==0 and is_size==io_size.
240 * For split blocks, there will be several of these.
242 typedef struct indirect_split
{
243 list_node_t is_node
; /* link on iv_splits */
246 * is_split_offset is the offset into the i/o.
247 * This is the sum of the previous splits' is_size's.
249 uint64_t is_split_offset
;
251 vdev_t
*is_vdev
; /* top-level vdev */
252 uint64_t is_target_offset
; /* offset on is_vdev */
254 int is_children
; /* number of entries in is_child[] */
257 * is_good_child is the child that we are currently using to
258 * attempt reconstruction.
262 indirect_child_t is_child
[1]; /* variable-length */
266 * The indirect_vsd_t is associated with each i/o to the indirect vdev.
267 * It is the "Vdev-Specific Data" in the zio_t's io_vsd.
269 typedef struct indirect_vsd
{
270 boolean_t iv_split_block
;
271 boolean_t iv_reconstruct
;
273 list_t iv_splits
; /* list of indirect_split_t's */
277 vdev_indirect_map_free(zio_t
*zio
)
279 indirect_vsd_t
*iv
= zio
->io_vsd
;
281 indirect_split_t
*is
;
282 while ((is
= list_head(&iv
->iv_splits
)) != NULL
) {
283 for (int c
= 0; c
< is
->is_children
; c
++) {
284 indirect_child_t
*ic
= &is
->is_child
[c
];
285 if (ic
->ic_data
!= NULL
)
286 abd_free(ic
->ic_data
);
288 list_remove(&iv
->iv_splits
, is
);
290 offsetof(indirect_split_t
, is_child
[is
->is_children
]));
292 kmem_free(iv
, sizeof (*iv
));
295 static const zio_vsd_ops_t vdev_indirect_vsd_ops
= {
296 .vsd_free
= vdev_indirect_map_free
,
297 .vsd_cksum_report
= zio_vsd_default_cksum_report
301 * Mark the given offset and size as being obsolete in the given txg.
304 vdev_indirect_mark_obsolete(vdev_t
*vd
, uint64_t offset
, uint64_t size
,
307 spa_t
*spa
= vd
->vdev_spa
;
308 ASSERT3U(spa_syncing_txg(spa
), ==, txg
);
309 ASSERT3U(vd
->vdev_indirect_config
.vic_mapping_object
, !=, 0);
310 ASSERT(vd
->vdev_removing
|| vd
->vdev_ops
== &vdev_indirect_ops
);
312 VERIFY(vdev_indirect_mapping_entry_for_offset(
313 vd
->vdev_indirect_mapping
, offset
) != NULL
);
315 if (spa_feature_is_enabled(spa
, SPA_FEATURE_OBSOLETE_COUNTS
)) {
316 mutex_enter(&vd
->vdev_obsolete_lock
);
317 range_tree_add(vd
->vdev_obsolete_segments
, offset
, size
);
318 mutex_exit(&vd
->vdev_obsolete_lock
);
319 vdev_dirty(vd
, 0, NULL
, txg
);
324 * Mark the DVA vdev_id:offset:size as being obsolete in the given tx. This
325 * wrapper is provided because the DMU does not know about vdev_t's and
326 * cannot directly call vdev_indirect_mark_obsolete.
329 spa_vdev_indirect_mark_obsolete(spa_t
*spa
, uint64_t vdev_id
, uint64_t offset
,
330 uint64_t size
, dmu_tx_t
*tx
)
332 vdev_t
*vd
= vdev_lookup_top(spa
, vdev_id
);
333 ASSERT(dmu_tx_is_syncing(tx
));
335 /* The DMU can only remap indirect vdevs. */
336 ASSERT3P(vd
->vdev_ops
, ==, &vdev_indirect_ops
);
337 vdev_indirect_mark_obsolete(vd
, offset
, size
, dmu_tx_get_txg(tx
));
340 static spa_condensing_indirect_t
*
341 spa_condensing_indirect_create(spa_t
*spa
)
343 spa_condensing_indirect_phys_t
*scip
=
344 &spa
->spa_condensing_indirect_phys
;
345 spa_condensing_indirect_t
*sci
= kmem_zalloc(sizeof (*sci
), KM_SLEEP
);
346 objset_t
*mos
= spa
->spa_meta_objset
;
348 for (int i
= 0; i
< TXG_SIZE
; i
++) {
349 list_create(&sci
->sci_new_mapping_entries
[i
],
350 sizeof (vdev_indirect_mapping_entry_t
),
351 offsetof(vdev_indirect_mapping_entry_t
, vime_node
));
354 sci
->sci_new_mapping
=
355 vdev_indirect_mapping_open(mos
, scip
->scip_next_mapping_object
);
361 spa_condensing_indirect_destroy(spa_condensing_indirect_t
*sci
)
363 for (int i
= 0; i
< TXG_SIZE
; i
++)
364 list_destroy(&sci
->sci_new_mapping_entries
[i
]);
366 if (sci
->sci_new_mapping
!= NULL
)
367 vdev_indirect_mapping_close(sci
->sci_new_mapping
);
369 kmem_free(sci
, sizeof (*sci
));
373 vdev_indirect_should_condense(vdev_t
*vd
)
375 vdev_indirect_mapping_t
*vim
= vd
->vdev_indirect_mapping
;
376 spa_t
*spa
= vd
->vdev_spa
;
378 ASSERT(dsl_pool_sync_context(spa
->spa_dsl_pool
));
380 if (!zfs_condense_indirect_vdevs_enable
)
384 * We can only condense one indirect vdev at a time.
386 if (spa
->spa_condensing_indirect
!= NULL
)
389 if (spa_shutting_down(spa
))
393 * The mapping object size must not change while we are
394 * condensing, so we can only condense indirect vdevs
395 * (not vdevs that are still in the middle of being removed).
397 if (vd
->vdev_ops
!= &vdev_indirect_ops
)
401 * If nothing new has been marked obsolete, there is no
402 * point in condensing.
404 if (vd
->vdev_obsolete_sm
== NULL
) {
405 ASSERT0(vdev_obsolete_sm_object(vd
));
409 ASSERT(vd
->vdev_obsolete_sm
!= NULL
);
411 ASSERT3U(vdev_obsolete_sm_object(vd
), ==,
412 space_map_object(vd
->vdev_obsolete_sm
));
414 uint64_t bytes_mapped
= vdev_indirect_mapping_bytes_mapped(vim
);
415 uint64_t bytes_obsolete
= space_map_allocated(vd
->vdev_obsolete_sm
);
416 uint64_t mapping_size
= vdev_indirect_mapping_size(vim
);
417 uint64_t obsolete_sm_size
= space_map_length(vd
->vdev_obsolete_sm
);
419 ASSERT3U(bytes_obsolete
, <=, bytes_mapped
);
422 * If a high percentage of the bytes that are mapped have become
423 * obsolete, condense (unless the mapping is already small enough).
424 * This has a good chance of reducing the amount of memory used
427 if (bytes_obsolete
* 100 / bytes_mapped
>=
428 zfs_indirect_condense_obsolete_pct
&&
429 mapping_size
> zfs_condense_min_mapping_bytes
) {
430 zfs_dbgmsg("should condense vdev %llu because obsolete "
431 "spacemap covers %d%% of %lluMB mapping",
432 (u_longlong_t
)vd
->vdev_id
,
433 (int)(bytes_obsolete
* 100 / bytes_mapped
),
434 (u_longlong_t
)bytes_mapped
/ 1024 / 1024);
439 * If the obsolete space map takes up too much space on disk,
440 * condense in order to free up this disk space.
442 if (obsolete_sm_size
>= zfs_condense_max_obsolete_bytes
) {
443 zfs_dbgmsg("should condense vdev %llu because obsolete sm "
444 "length %lluMB >= max size %lluMB",
445 (u_longlong_t
)vd
->vdev_id
,
446 (u_longlong_t
)obsolete_sm_size
/ 1024 / 1024,
447 (u_longlong_t
)zfs_condense_max_obsolete_bytes
/
456 * This sync task completes (finishes) a condense, deleting the old
457 * mapping and replacing it with the new one.
460 spa_condense_indirect_complete_sync(void *arg
, dmu_tx_t
*tx
)
462 spa_condensing_indirect_t
*sci
= arg
;
463 spa_t
*spa
= dmu_tx_pool(tx
)->dp_spa
;
464 spa_condensing_indirect_phys_t
*scip
=
465 &spa
->spa_condensing_indirect_phys
;
466 vdev_t
*vd
= vdev_lookup_top(spa
, scip
->scip_vdev
);
467 vdev_indirect_config_t
*vic
= &vd
->vdev_indirect_config
;
468 objset_t
*mos
= spa
->spa_meta_objset
;
469 vdev_indirect_mapping_t
*old_mapping
= vd
->vdev_indirect_mapping
;
470 uint64_t old_count
= vdev_indirect_mapping_num_entries(old_mapping
);
472 vdev_indirect_mapping_num_entries(sci
->sci_new_mapping
);
474 ASSERT(dmu_tx_is_syncing(tx
));
475 ASSERT3P(vd
->vdev_ops
, ==, &vdev_indirect_ops
);
476 ASSERT3P(sci
, ==, spa
->spa_condensing_indirect
);
477 for (int i
= 0; i
< TXG_SIZE
; i
++) {
478 ASSERT(list_is_empty(&sci
->sci_new_mapping_entries
[i
]));
480 ASSERT(vic
->vic_mapping_object
!= 0);
481 ASSERT3U(vd
->vdev_id
, ==, scip
->scip_vdev
);
482 ASSERT(scip
->scip_next_mapping_object
!= 0);
483 ASSERT(scip
->scip_prev_obsolete_sm_object
!= 0);
486 * Reset vdev_indirect_mapping to refer to the new object.
488 rw_enter(&vd
->vdev_indirect_rwlock
, RW_WRITER
);
489 vdev_indirect_mapping_close(vd
->vdev_indirect_mapping
);
490 vd
->vdev_indirect_mapping
= sci
->sci_new_mapping
;
491 rw_exit(&vd
->vdev_indirect_rwlock
);
493 sci
->sci_new_mapping
= NULL
;
494 vdev_indirect_mapping_free(mos
, vic
->vic_mapping_object
, tx
);
495 vic
->vic_mapping_object
= scip
->scip_next_mapping_object
;
496 scip
->scip_next_mapping_object
= 0;
498 space_map_free_obj(mos
, scip
->scip_prev_obsolete_sm_object
, tx
);
499 spa_feature_decr(spa
, SPA_FEATURE_OBSOLETE_COUNTS
, tx
);
500 scip
->scip_prev_obsolete_sm_object
= 0;
504 VERIFY0(zap_remove(mos
, DMU_POOL_DIRECTORY_OBJECT
,
505 DMU_POOL_CONDENSING_INDIRECT
, tx
));
506 spa_condensing_indirect_destroy(spa
->spa_condensing_indirect
);
507 spa
->spa_condensing_indirect
= NULL
;
509 zfs_dbgmsg("finished condense of vdev %llu in txg %llu: "
510 "new mapping object %llu has %llu entries "
511 "(was %llu entries)",
512 vd
->vdev_id
, dmu_tx_get_txg(tx
), vic
->vic_mapping_object
,
513 new_count
, old_count
);
515 vdev_config_dirty(spa
->spa_root_vdev
);
519 * This sync task appends entries to the new mapping object.
522 spa_condense_indirect_commit_sync(void *arg
, dmu_tx_t
*tx
)
524 spa_condensing_indirect_t
*sci
= arg
;
525 uint64_t txg
= dmu_tx_get_txg(tx
);
526 ASSERTV(spa_t
*spa
= dmu_tx_pool(tx
)->dp_spa
);
528 ASSERT(dmu_tx_is_syncing(tx
));
529 ASSERT3P(sci
, ==, spa
->spa_condensing_indirect
);
531 vdev_indirect_mapping_add_entries(sci
->sci_new_mapping
,
532 &sci
->sci_new_mapping_entries
[txg
& TXG_MASK
], tx
);
533 ASSERT(list_is_empty(&sci
->sci_new_mapping_entries
[txg
& TXG_MASK
]));
537 * Open-context function to add one entry to the new mapping. The new
538 * entry will be remembered and written from syncing context.
541 spa_condense_indirect_commit_entry(spa_t
*spa
,
542 vdev_indirect_mapping_entry_phys_t
*vimep
, uint32_t count
)
544 spa_condensing_indirect_t
*sci
= spa
->spa_condensing_indirect
;
546 ASSERT3U(count
, <, DVA_GET_ASIZE(&vimep
->vimep_dst
));
548 dmu_tx_t
*tx
= dmu_tx_create_dd(spa_get_dsl(spa
)->dp_mos_dir
);
549 dmu_tx_hold_space(tx
, sizeof (*vimep
) + sizeof (count
));
550 VERIFY0(dmu_tx_assign(tx
, TXG_WAIT
));
551 int txgoff
= dmu_tx_get_txg(tx
) & TXG_MASK
;
554 * If we are the first entry committed this txg, kick off the sync
555 * task to write to the MOS on our behalf.
557 if (list_is_empty(&sci
->sci_new_mapping_entries
[txgoff
])) {
558 dsl_sync_task_nowait(dmu_tx_pool(tx
),
559 spa_condense_indirect_commit_sync
, sci
,
560 0, ZFS_SPACE_CHECK_NONE
, tx
);
563 vdev_indirect_mapping_entry_t
*vime
=
564 kmem_alloc(sizeof (*vime
), KM_SLEEP
);
565 vime
->vime_mapping
= *vimep
;
566 vime
->vime_obsolete_count
= count
;
567 list_insert_tail(&sci
->sci_new_mapping_entries
[txgoff
], vime
);
573 spa_condense_indirect_generate_new_mapping(vdev_t
*vd
,
574 uint32_t *obsolete_counts
, uint64_t start_index
, zthr_t
*zthr
)
576 spa_t
*spa
= vd
->vdev_spa
;
577 uint64_t mapi
= start_index
;
578 vdev_indirect_mapping_t
*old_mapping
= vd
->vdev_indirect_mapping
;
579 uint64_t old_num_entries
=
580 vdev_indirect_mapping_num_entries(old_mapping
);
582 ASSERT3P(vd
->vdev_ops
, ==, &vdev_indirect_ops
);
583 ASSERT3U(vd
->vdev_id
, ==, spa
->spa_condensing_indirect_phys
.scip_vdev
);
585 zfs_dbgmsg("starting condense of vdev %llu from index %llu",
586 (u_longlong_t
)vd
->vdev_id
,
589 while (mapi
< old_num_entries
) {
591 if (zthr_iscancelled(zthr
)) {
592 zfs_dbgmsg("pausing condense of vdev %llu "
593 "at index %llu", (u_longlong_t
)vd
->vdev_id
,
598 vdev_indirect_mapping_entry_phys_t
*entry
=
599 &old_mapping
->vim_entries
[mapi
];
600 uint64_t entry_size
= DVA_GET_ASIZE(&entry
->vimep_dst
);
601 ASSERT3U(obsolete_counts
[mapi
], <=, entry_size
);
602 if (obsolete_counts
[mapi
] < entry_size
) {
603 spa_condense_indirect_commit_entry(spa
, entry
,
604 obsolete_counts
[mapi
]);
607 * This delay may be requested for testing, debugging,
608 * or performance reasons.
610 hrtime_t now
= gethrtime();
611 hrtime_t sleep_until
= now
+ MSEC2NSEC(
612 zfs_condense_indirect_commit_entry_delay_ms
);
613 zfs_sleep_until(sleep_until
);
622 spa_condense_indirect_thread_check(void *arg
, zthr_t
*zthr
)
626 return (spa
->spa_condensing_indirect
!= NULL
);
631 spa_condense_indirect_thread(void *arg
, zthr_t
*zthr
)
636 ASSERT3P(spa
->spa_condensing_indirect
, !=, NULL
);
637 spa_config_enter(spa
, SCL_VDEV
, FTAG
, RW_READER
);
638 vd
= vdev_lookup_top(spa
, spa
->spa_condensing_indirect_phys
.scip_vdev
);
639 ASSERT3P(vd
, !=, NULL
);
640 spa_config_exit(spa
, SCL_VDEV
, FTAG
);
642 spa_condensing_indirect_t
*sci
= spa
->spa_condensing_indirect
;
643 spa_condensing_indirect_phys_t
*scip
=
644 &spa
->spa_condensing_indirect_phys
;
646 uint64_t start_index
;
647 vdev_indirect_mapping_t
*old_mapping
= vd
->vdev_indirect_mapping
;
648 space_map_t
*prev_obsolete_sm
= NULL
;
650 ASSERT3U(vd
->vdev_id
, ==, scip
->scip_vdev
);
651 ASSERT(scip
->scip_next_mapping_object
!= 0);
652 ASSERT(scip
->scip_prev_obsolete_sm_object
!= 0);
653 ASSERT3P(vd
->vdev_ops
, ==, &vdev_indirect_ops
);
655 for (int i
= 0; i
< TXG_SIZE
; i
++) {
657 * The list must start out empty in order for the
658 * _commit_sync() sync task to be properly registered
659 * on the first call to _commit_entry(); so it's wise
660 * to double check and ensure we actually are starting
663 ASSERT(list_is_empty(&sci
->sci_new_mapping_entries
[i
]));
666 VERIFY0(space_map_open(&prev_obsolete_sm
, spa
->spa_meta_objset
,
667 scip
->scip_prev_obsolete_sm_object
, 0, vd
->vdev_asize
, 0));
668 space_map_update(prev_obsolete_sm
);
669 counts
= vdev_indirect_mapping_load_obsolete_counts(old_mapping
);
670 if (prev_obsolete_sm
!= NULL
) {
671 vdev_indirect_mapping_load_obsolete_spacemap(old_mapping
,
672 counts
, prev_obsolete_sm
);
674 space_map_close(prev_obsolete_sm
);
677 * Generate new mapping. Determine what index to continue from
678 * based on the max offset that we've already written in the
681 uint64_t max_offset
=
682 vdev_indirect_mapping_max_offset(sci
->sci_new_mapping
);
683 if (max_offset
== 0) {
684 /* We haven't written anything to the new mapping yet. */
688 * Pick up from where we left off. _entry_for_offset()
689 * returns a pointer into the vim_entries array. If
690 * max_offset is greater than any of the mappings
691 * contained in the table NULL will be returned and
692 * that indicates we've exhausted our iteration of the
696 vdev_indirect_mapping_entry_phys_t
*entry
=
697 vdev_indirect_mapping_entry_for_offset_or_next(old_mapping
,
702 * We've already written the whole new mapping.
703 * This special value will cause us to skip the
704 * generate_new_mapping step and just do the sync
705 * task to complete the condense.
707 start_index
= UINT64_MAX
;
709 start_index
= entry
- old_mapping
->vim_entries
;
710 ASSERT3U(start_index
, <,
711 vdev_indirect_mapping_num_entries(old_mapping
));
715 spa_condense_indirect_generate_new_mapping(vd
, counts
,
718 vdev_indirect_mapping_free_obsolete_counts(old_mapping
, counts
);
721 * If the zthr has received a cancellation signal while running
722 * in generate_new_mapping() or at any point after that, then bail
723 * early. We don't want to complete the condense if the spa is
726 if (zthr_iscancelled(zthr
))
729 VERIFY0(dsl_sync_task(spa_name(spa
), NULL
,
730 spa_condense_indirect_complete_sync
, sci
, 0, ZFS_SPACE_CHECK_NONE
));
736 * Sync task to begin the condensing process.
739 spa_condense_indirect_start_sync(vdev_t
*vd
, dmu_tx_t
*tx
)
741 spa_t
*spa
= vd
->vdev_spa
;
742 spa_condensing_indirect_phys_t
*scip
=
743 &spa
->spa_condensing_indirect_phys
;
745 ASSERT0(scip
->scip_next_mapping_object
);
746 ASSERT0(scip
->scip_prev_obsolete_sm_object
);
747 ASSERT0(scip
->scip_vdev
);
748 ASSERT(dmu_tx_is_syncing(tx
));
749 ASSERT3P(vd
->vdev_ops
, ==, &vdev_indirect_ops
);
750 ASSERT(spa_feature_is_active(spa
, SPA_FEATURE_OBSOLETE_COUNTS
));
751 ASSERT(vdev_indirect_mapping_num_entries(vd
->vdev_indirect_mapping
));
753 uint64_t obsolete_sm_obj
= vdev_obsolete_sm_object(vd
);
754 ASSERT(obsolete_sm_obj
!= 0);
756 scip
->scip_vdev
= vd
->vdev_id
;
757 scip
->scip_next_mapping_object
=
758 vdev_indirect_mapping_alloc(spa
->spa_meta_objset
, tx
);
760 scip
->scip_prev_obsolete_sm_object
= obsolete_sm_obj
;
763 * We don't need to allocate a new space map object, since
764 * vdev_indirect_sync_obsolete will allocate one when needed.
766 space_map_close(vd
->vdev_obsolete_sm
);
767 vd
->vdev_obsolete_sm
= NULL
;
768 VERIFY0(zap_remove(spa
->spa_meta_objset
, vd
->vdev_top_zap
,
769 VDEV_TOP_ZAP_INDIRECT_OBSOLETE_SM
, tx
));
771 VERIFY0(zap_add(spa
->spa_dsl_pool
->dp_meta_objset
,
772 DMU_POOL_DIRECTORY_OBJECT
,
773 DMU_POOL_CONDENSING_INDIRECT
, sizeof (uint64_t),
774 sizeof (*scip
) / sizeof (uint64_t), scip
, tx
));
776 ASSERT3P(spa
->spa_condensing_indirect
, ==, NULL
);
777 spa
->spa_condensing_indirect
= spa_condensing_indirect_create(spa
);
779 zfs_dbgmsg("starting condense of vdev %llu in txg %llu: "
781 vd
->vdev_id
, dmu_tx_get_txg(tx
),
782 (u_longlong_t
)scip
->scip_prev_obsolete_sm_object
,
783 (u_longlong_t
)scip
->scip_next_mapping_object
);
785 zthr_wakeup(spa
->spa_condense_zthr
);
789 * Sync to the given vdev's obsolete space map any segments that are no longer
790 * referenced as of the given txg.
792 * If the obsolete space map doesn't exist yet, create and open it.
795 vdev_indirect_sync_obsolete(vdev_t
*vd
, dmu_tx_t
*tx
)
797 spa_t
*spa
= vd
->vdev_spa
;
798 ASSERTV(vdev_indirect_config_t
*vic
= &vd
->vdev_indirect_config
);
800 ASSERT3U(vic
->vic_mapping_object
, !=, 0);
801 ASSERT(range_tree_space(vd
->vdev_obsolete_segments
) > 0);
802 ASSERT(vd
->vdev_removing
|| vd
->vdev_ops
== &vdev_indirect_ops
);
803 ASSERT(spa_feature_is_enabled(spa
, SPA_FEATURE_OBSOLETE_COUNTS
));
805 if (vdev_obsolete_sm_object(vd
) == 0) {
806 uint64_t obsolete_sm_object
=
807 space_map_alloc(spa
->spa_meta_objset
, tx
);
809 ASSERT(vd
->vdev_top_zap
!= 0);
810 VERIFY0(zap_add(vd
->vdev_spa
->spa_meta_objset
, vd
->vdev_top_zap
,
811 VDEV_TOP_ZAP_INDIRECT_OBSOLETE_SM
,
812 sizeof (obsolete_sm_object
), 1, &obsolete_sm_object
, tx
));
813 ASSERT3U(vdev_obsolete_sm_object(vd
), !=, 0);
815 spa_feature_incr(spa
, SPA_FEATURE_OBSOLETE_COUNTS
, tx
);
816 VERIFY0(space_map_open(&vd
->vdev_obsolete_sm
,
817 spa
->spa_meta_objset
, obsolete_sm_object
,
818 0, vd
->vdev_asize
, 0));
819 space_map_update(vd
->vdev_obsolete_sm
);
822 ASSERT(vd
->vdev_obsolete_sm
!= NULL
);
823 ASSERT3U(vdev_obsolete_sm_object(vd
), ==,
824 space_map_object(vd
->vdev_obsolete_sm
));
826 space_map_write(vd
->vdev_obsolete_sm
,
827 vd
->vdev_obsolete_segments
, SM_ALLOC
, tx
);
828 space_map_update(vd
->vdev_obsolete_sm
);
829 range_tree_vacate(vd
->vdev_obsolete_segments
, NULL
, NULL
);
833 spa_condense_init(spa_t
*spa
)
835 int error
= zap_lookup(spa
->spa_meta_objset
,
836 DMU_POOL_DIRECTORY_OBJECT
,
837 DMU_POOL_CONDENSING_INDIRECT
, sizeof (uint64_t),
838 sizeof (spa
->spa_condensing_indirect_phys
) / sizeof (uint64_t),
839 &spa
->spa_condensing_indirect_phys
);
841 if (spa_writeable(spa
)) {
842 spa
->spa_condensing_indirect
=
843 spa_condensing_indirect_create(spa
);
846 } else if (error
== ENOENT
) {
854 spa_condense_fini(spa_t
*spa
)
856 if (spa
->spa_condensing_indirect
!= NULL
) {
857 spa_condensing_indirect_destroy(spa
->spa_condensing_indirect
);
858 spa
->spa_condensing_indirect
= NULL
;
863 spa_start_indirect_condensing_thread(spa_t
*spa
)
865 ASSERT3P(spa
->spa_condense_zthr
, ==, NULL
);
866 spa
->spa_condense_zthr
= zthr_create(spa_condense_indirect_thread_check
,
867 spa_condense_indirect_thread
, spa
);
871 * Gets the obsolete spacemap object from the vdev's ZAP.
872 * Returns the spacemap object, or 0 if it wasn't in the ZAP or the ZAP doesn't
876 vdev_obsolete_sm_object(vdev_t
*vd
)
878 ASSERT0(spa_config_held(vd
->vdev_spa
, SCL_ALL
, RW_WRITER
));
879 if (vd
->vdev_top_zap
== 0) {
885 err
= zap_lookup(vd
->vdev_spa
->spa_meta_objset
, vd
->vdev_top_zap
,
886 VDEV_TOP_ZAP_INDIRECT_OBSOLETE_SM
, sizeof (sm_obj
), 1, &sm_obj
);
888 ASSERT(err
== 0 || err
== ENOENT
);
894 vdev_obsolete_counts_are_precise(vdev_t
*vd
)
896 ASSERT0(spa_config_held(vd
->vdev_spa
, SCL_ALL
, RW_WRITER
));
897 if (vd
->vdev_top_zap
== 0) {
903 err
= zap_lookup(vd
->vdev_spa
->spa_meta_objset
, vd
->vdev_top_zap
,
904 VDEV_TOP_ZAP_OBSOLETE_COUNTS_ARE_PRECISE
, sizeof (val
), 1, &val
);
906 ASSERT(err
== 0 || err
== ENOENT
);
913 vdev_indirect_close(vdev_t
*vd
)
919 vdev_indirect_open(vdev_t
*vd
, uint64_t *psize
, uint64_t *max_psize
,
922 *psize
= *max_psize
= vd
->vdev_asize
+
923 VDEV_LABEL_START_SIZE
+ VDEV_LABEL_END_SIZE
;
924 *ashift
= vd
->vdev_ashift
;
928 typedef struct remap_segment
{
932 uint64_t rs_split_offset
;
937 rs_alloc(vdev_t
*vd
, uint64_t offset
, uint64_t asize
, uint64_t split_offset
)
939 remap_segment_t
*rs
= kmem_alloc(sizeof (remap_segment_t
), KM_SLEEP
);
941 rs
->rs_offset
= offset
;
942 rs
->rs_asize
= asize
;
943 rs
->rs_split_offset
= split_offset
;
948 * Given an indirect vdev and an extent on that vdev, it duplicates the
949 * physical entries of the indirect mapping that correspond to the extent
950 * to a new array and returns a pointer to it. In addition, copied_entries
951 * is populated with the number of mapping entries that were duplicated.
953 * Note that the function assumes that the caller holds vdev_indirect_rwlock.
954 * This ensures that the mapping won't change due to condensing as we
955 * copy over its contents.
957 * Finally, since we are doing an allocation, it is up to the caller to
958 * free the array allocated in this function.
960 vdev_indirect_mapping_entry_phys_t
*
961 vdev_indirect_mapping_duplicate_adjacent_entries(vdev_t
*vd
, uint64_t offset
,
962 uint64_t asize
, uint64_t *copied_entries
)
964 vdev_indirect_mapping_entry_phys_t
*duplicate_mappings
= NULL
;
965 vdev_indirect_mapping_t
*vim
= vd
->vdev_indirect_mapping
;
966 uint64_t entries
= 0;
968 ASSERT(RW_READ_HELD(&vd
->vdev_indirect_rwlock
));
970 vdev_indirect_mapping_entry_phys_t
*first_mapping
=
971 vdev_indirect_mapping_entry_for_offset(vim
, offset
);
972 ASSERT3P(first_mapping
, !=, NULL
);
974 vdev_indirect_mapping_entry_phys_t
*m
= first_mapping
;
976 uint64_t size
= DVA_GET_ASIZE(&m
->vimep_dst
);
978 ASSERT3U(offset
, >=, DVA_MAPPING_GET_SRC_OFFSET(m
));
979 ASSERT3U(offset
, <, DVA_MAPPING_GET_SRC_OFFSET(m
) + size
);
981 uint64_t inner_offset
= offset
- DVA_MAPPING_GET_SRC_OFFSET(m
);
982 uint64_t inner_size
= MIN(asize
, size
- inner_offset
);
984 offset
+= inner_size
;
990 size_t copy_length
= entries
* sizeof (*first_mapping
);
991 duplicate_mappings
= kmem_alloc(copy_length
, KM_SLEEP
);
992 bcopy(first_mapping
, duplicate_mappings
, copy_length
);
993 *copied_entries
= entries
;
995 return (duplicate_mappings
);
999 * Goes through the relevant indirect mappings until it hits a concrete vdev
1000 * and issues the callback. On the way to the concrete vdev, if any other
1001 * indirect vdevs are encountered, then the callback will also be called on
1002 * each of those indirect vdevs. For example, if the segment is mapped to
1003 * segment A on indirect vdev 1, and then segment A on indirect vdev 1 is
1004 * mapped to segment B on concrete vdev 2, then the callback will be called on
1005 * both vdev 1 and vdev 2.
1007 * While the callback passed to vdev_indirect_remap() is called on every vdev
1008 * the function encounters, certain callbacks only care about concrete vdevs.
1009 * These types of callbacks should return immediately and explicitly when they
1010 * are called on an indirect vdev.
1012 * Because there is a possibility that a DVA section in the indirect device
1013 * has been split into multiple sections in our mapping, we keep track
1014 * of the relevant contiguous segments of the new location (remap_segment_t)
1015 * in a stack. This way we can call the callback for each of the new sections
1016 * created by a single section of the indirect device. Note though, that in
1017 * this scenario the callbacks in each split block won't occur in-order in
1018 * terms of offset, so callers should not make any assumptions about that.
1020 * For callbacks that don't handle split blocks and immediately return when
1021 * they encounter them (as is the case for remap_blkptr_cb), the caller can
1022 * assume that its callback will be applied from the first indirect vdev
1023 * encountered to the last one and then the concrete vdev, in that order.
1026 vdev_indirect_remap(vdev_t
*vd
, uint64_t offset
, uint64_t asize
,
1027 void (*func
)(uint64_t, vdev_t
*, uint64_t, uint64_t, void *), void *arg
)
1030 spa_t
*spa
= vd
->vdev_spa
;
1032 list_create(&stack
, sizeof (remap_segment_t
),
1033 offsetof(remap_segment_t
, rs_node
));
1035 for (remap_segment_t
*rs
= rs_alloc(vd
, offset
, asize
, 0);
1036 rs
!= NULL
; rs
= list_remove_head(&stack
)) {
1037 vdev_t
*v
= rs
->rs_vd
;
1038 uint64_t num_entries
= 0;
1040 ASSERT(spa_config_held(spa
, SCL_ALL
, RW_READER
) != 0);
1041 ASSERT(rs
->rs_asize
> 0);
1044 * Note: As this function can be called from open context
1045 * (e.g. zio_read()), we need the following rwlock to
1046 * prevent the mapping from being changed by condensing.
1048 * So we grab the lock and we make a copy of the entries
1049 * that are relevant to the extent that we are working on.
1050 * Once that is done, we drop the lock and iterate over
1051 * our copy of the mapping. Once we are done with the with
1052 * the remap segment and we free it, we also free our copy
1053 * of the indirect mapping entries that are relevant to it.
1055 * This way we don't need to wait until the function is
1056 * finished with a segment, to condense it. In addition, we
1057 * don't need a recursive rwlock for the case that a call to
1058 * vdev_indirect_remap() needs to call itself (through the
1059 * codepath of its callback) for the same vdev in the middle
1062 rw_enter(&v
->vdev_indirect_rwlock
, RW_READER
);
1063 ASSERT3P(v
->vdev_indirect_mapping
, !=, NULL
);
1065 vdev_indirect_mapping_entry_phys_t
*mapping
=
1066 vdev_indirect_mapping_duplicate_adjacent_entries(v
,
1067 rs
->rs_offset
, rs
->rs_asize
, &num_entries
);
1068 ASSERT3P(mapping
, !=, NULL
);
1069 ASSERT3U(num_entries
, >, 0);
1070 rw_exit(&v
->vdev_indirect_rwlock
);
1072 for (uint64_t i
= 0; i
< num_entries
; i
++) {
1074 * Note: the vdev_indirect_mapping can not change
1075 * while we are running. It only changes while the
1076 * removal is in progress, and then only from syncing
1077 * context. While a removal is in progress, this
1078 * function is only called for frees, which also only
1079 * happen from syncing context.
1081 vdev_indirect_mapping_entry_phys_t
*m
= &mapping
[i
];
1083 ASSERT3P(m
, !=, NULL
);
1084 ASSERT3U(rs
->rs_asize
, >, 0);
1086 uint64_t size
= DVA_GET_ASIZE(&m
->vimep_dst
);
1087 uint64_t dst_offset
= DVA_GET_OFFSET(&m
->vimep_dst
);
1088 uint64_t dst_vdev
= DVA_GET_VDEV(&m
->vimep_dst
);
1090 ASSERT3U(rs
->rs_offset
, >=,
1091 DVA_MAPPING_GET_SRC_OFFSET(m
));
1092 ASSERT3U(rs
->rs_offset
, <,
1093 DVA_MAPPING_GET_SRC_OFFSET(m
) + size
);
1094 ASSERT3U(dst_vdev
, !=, v
->vdev_id
);
1096 uint64_t inner_offset
= rs
->rs_offset
-
1097 DVA_MAPPING_GET_SRC_OFFSET(m
);
1098 uint64_t inner_size
=
1099 MIN(rs
->rs_asize
, size
- inner_offset
);
1101 vdev_t
*dst_v
= vdev_lookup_top(spa
, dst_vdev
);
1102 ASSERT3P(dst_v
, !=, NULL
);
1104 if (dst_v
->vdev_ops
== &vdev_indirect_ops
) {
1105 list_insert_head(&stack
,
1106 rs_alloc(dst_v
, dst_offset
+ inner_offset
,
1107 inner_size
, rs
->rs_split_offset
));
1111 if ((zfs_flags
& ZFS_DEBUG_INDIRECT_REMAP
) &&
1112 IS_P2ALIGNED(inner_size
, 2 * SPA_MINBLOCKSIZE
)) {
1114 * Note: This clause exists only solely for
1115 * testing purposes. We use it to ensure that
1116 * split blocks work and that the callbacks
1117 * using them yield the same result if issued
1120 uint64_t inner_half
= inner_size
/ 2;
1122 func(rs
->rs_split_offset
+ inner_half
, dst_v
,
1123 dst_offset
+ inner_offset
+ inner_half
,
1126 func(rs
->rs_split_offset
, dst_v
,
1127 dst_offset
+ inner_offset
,
1130 func(rs
->rs_split_offset
, dst_v
,
1131 dst_offset
+ inner_offset
,
1135 rs
->rs_offset
+= inner_size
;
1136 rs
->rs_asize
-= inner_size
;
1137 rs
->rs_split_offset
+= inner_size
;
1139 VERIFY0(rs
->rs_asize
);
1141 kmem_free(mapping
, num_entries
* sizeof (*mapping
));
1142 kmem_free(rs
, sizeof (remap_segment_t
));
1144 list_destroy(&stack
);
1148 vdev_indirect_child_io_done(zio_t
*zio
)
1150 zio_t
*pio
= zio
->io_private
;
1152 mutex_enter(&pio
->io_lock
);
1153 pio
->io_error
= zio_worst_error(pio
->io_error
, zio
->io_error
);
1154 mutex_exit(&pio
->io_lock
);
1156 abd_put(zio
->io_abd
);
1160 * This is a callback for vdev_indirect_remap() which allocates an
1161 * indirect_split_t for each split segment and adds it to iv_splits.
1164 vdev_indirect_gather_splits(uint64_t split_offset
, vdev_t
*vd
, uint64_t offset
,
1165 uint64_t size
, void *arg
)
1168 indirect_vsd_t
*iv
= zio
->io_vsd
;
1170 ASSERT3P(vd
, !=, NULL
);
1172 if (vd
->vdev_ops
== &vdev_indirect_ops
)
1176 if (vd
->vdev_ops
== &vdev_mirror_ops
)
1177 n
= vd
->vdev_children
;
1179 indirect_split_t
*is
=
1180 kmem_zalloc(offsetof(indirect_split_t
, is_child
[n
]), KM_SLEEP
);
1182 is
->is_children
= n
;
1184 is
->is_split_offset
= split_offset
;
1185 is
->is_target_offset
= offset
;
1189 * Note that we only consider multiple copies of the data for
1190 * *mirror* vdevs. We don't for "replacing" or "spare" vdevs, even
1191 * though they use the same ops as mirror, because there's only one
1192 * "good" copy under the replacing/spare.
1194 if (vd
->vdev_ops
== &vdev_mirror_ops
) {
1195 for (int i
= 0; i
< n
; i
++) {
1196 is
->is_child
[i
].ic_vdev
= vd
->vdev_child
[i
];
1199 is
->is_child
[0].ic_vdev
= vd
;
1202 list_insert_tail(&iv
->iv_splits
, is
);
1206 vdev_indirect_read_split_done(zio_t
*zio
)
1208 indirect_child_t
*ic
= zio
->io_private
;
1210 if (zio
->io_error
!= 0) {
1212 * Clear ic_data to indicate that we do not have data for this
1215 abd_free(ic
->ic_data
);
1221 * Issue reads for all copies (mirror children) of all splits.
1224 vdev_indirect_read_all(zio_t
*zio
)
1226 indirect_vsd_t
*iv
= zio
->io_vsd
;
1228 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1229 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1230 for (int i
= 0; i
< is
->is_children
; i
++) {
1231 indirect_child_t
*ic
= &is
->is_child
[i
];
1233 if (!vdev_readable(ic
->ic_vdev
))
1237 * Note, we may read from a child whose DTL
1238 * indicates that the data may not be present here.
1239 * While this might result in a few i/os that will
1240 * likely return incorrect data, it simplifies the
1241 * code since we can treat scrub and resilver
1242 * identically. (The incorrect data will be
1243 * detected and ignored when we verify the
1247 ic
->ic_data
= abd_alloc_sametype(zio
->io_abd
,
1249 ic
->ic_duplicate
= -1;
1251 zio_nowait(zio_vdev_child_io(zio
, NULL
,
1252 ic
->ic_vdev
, is
->is_target_offset
, ic
->ic_data
,
1253 is
->is_size
, zio
->io_type
, zio
->io_priority
, 0,
1254 vdev_indirect_read_split_done
, ic
));
1257 iv
->iv_reconstruct
= B_TRUE
;
1261 vdev_indirect_io_start(zio_t
*zio
)
1263 ASSERTV(spa_t
*spa
= zio
->io_spa
);
1264 indirect_vsd_t
*iv
= kmem_zalloc(sizeof (*iv
), KM_SLEEP
);
1265 list_create(&iv
->iv_splits
,
1266 sizeof (indirect_split_t
), offsetof(indirect_split_t
, is_node
));
1269 zio
->io_vsd_ops
= &vdev_indirect_vsd_ops
;
1271 ASSERT(spa_config_held(spa
, SCL_ALL
, RW_READER
) != 0);
1272 if (zio
->io_type
!= ZIO_TYPE_READ
) {
1273 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
,
1305 abd_get_offset(zio
->io_abd
, 0),
1306 zio
->io_size
, zio
->io_type
, zio
->io_priority
, 0,
1307 vdev_indirect_child_io_done
, zio
));
1309 iv
->iv_split_block
= B_TRUE
;
1310 if (zio
->io_flags
& (ZIO_FLAG_SCRUB
| ZIO_FLAG_RESILVER
)) {
1312 * Read all copies. Note that for simplicity,
1313 * we don't bother consulting the DTL in the
1316 vdev_indirect_read_all(zio
);
1319 * Read one copy of each split segment, from the
1320 * top-level vdev. Since we don't know the
1321 * checksum of each split individually, the child
1322 * zio can't ensure that we get the right data.
1323 * E.g. if it's a mirror, it will just read from a
1324 * random (healthy) leaf vdev. We have to verify
1325 * the checksum in vdev_indirect_io_done().
1327 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1328 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1329 zio_nowait(zio_vdev_child_io(zio
, NULL
,
1330 is
->is_vdev
, is
->is_target_offset
,
1331 abd_get_offset(zio
->io_abd
,
1332 is
->is_split_offset
), is
->is_size
,
1333 zio
->io_type
, zio
->io_priority
, 0,
1334 vdev_indirect_child_io_done
, zio
));
1344 * Report a checksum error for a child.
1347 vdev_indirect_checksum_error(zio_t
*zio
,
1348 indirect_split_t
*is
, indirect_child_t
*ic
)
1350 vdev_t
*vd
= ic
->ic_vdev
;
1352 if (zio
->io_flags
& ZIO_FLAG_SPECULATIVE
)
1355 mutex_enter(&vd
->vdev_stat_lock
);
1356 vd
->vdev_stat
.vs_checksum_errors
++;
1357 mutex_exit(&vd
->vdev_stat_lock
);
1359 zio_bad_cksum_t zbc
= {{{ 0 }}};
1360 abd_t
*bad_abd
= ic
->ic_data
;
1361 abd_t
*good_abd
= is
->is_child
[is
->is_good_child
].ic_data
;
1362 zfs_ereport_post_checksum(zio
->io_spa
, vd
, NULL
, zio
,
1363 is
->is_target_offset
, is
->is_size
, good_abd
, bad_abd
, &zbc
);
1367 * Issue repair i/os for any incorrect copies. We do this by comparing
1368 * each split segment's correct data (is_good_child's ic_data) with each
1369 * other copy of the data. If they differ, then we overwrite the bad data
1370 * with the good copy. Note that we do this without regard for the DTL's,
1371 * which simplifies this code and also issues the optimal number of writes
1372 * (based on which copies actually read bad data, as opposed to which we
1373 * think might be wrong). For the same reason, we always use
1374 * ZIO_FLAG_SELF_HEAL, to bypass the DTL check in zio_vdev_io_start().
1377 vdev_indirect_repair(zio_t
*zio
)
1379 indirect_vsd_t
*iv
= zio
->io_vsd
;
1381 enum zio_flag flags
= ZIO_FLAG_IO_REPAIR
;
1383 if (!(zio
->io_flags
& (ZIO_FLAG_SCRUB
| ZIO_FLAG_RESILVER
)))
1384 flags
|= ZIO_FLAG_SELF_HEAL
;
1386 if (!spa_writeable(zio
->io_spa
))
1389 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1390 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1391 indirect_child_t
*good_child
= &is
->is_child
[is
->is_good_child
];
1393 for (int c
= 0; c
< is
->is_children
; c
++) {
1394 indirect_child_t
*ic
= &is
->is_child
[c
];
1395 if (ic
== good_child
)
1397 if (ic
->ic_data
== NULL
)
1399 if (ic
->ic_duplicate
== is
->is_good_child
)
1402 zio_nowait(zio_vdev_child_io(zio
, NULL
,
1403 ic
->ic_vdev
, is
->is_target_offset
,
1404 good_child
->ic_data
, is
->is_size
,
1405 ZIO_TYPE_WRITE
, ZIO_PRIORITY_ASYNC_WRITE
,
1406 ZIO_FLAG_IO_REPAIR
| ZIO_FLAG_SELF_HEAL
,
1409 vdev_indirect_checksum_error(zio
, is
, ic
);
1415 * Report checksum errors on all children that we read from.
1418 vdev_indirect_all_checksum_errors(zio_t
*zio
)
1420 indirect_vsd_t
*iv
= zio
->io_vsd
;
1422 if (zio
->io_flags
& ZIO_FLAG_SPECULATIVE
)
1425 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1426 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1427 for (int c
= 0; c
< is
->is_children
; c
++) {
1428 indirect_child_t
*ic
= &is
->is_child
[c
];
1430 if (ic
->ic_data
== NULL
)
1433 vdev_t
*vd
= ic
->ic_vdev
;
1435 mutex_enter(&vd
->vdev_stat_lock
);
1436 vd
->vdev_stat
.vs_checksum_errors
++;
1437 mutex_exit(&vd
->vdev_stat_lock
);
1439 zfs_ereport_post_checksum(zio
->io_spa
, vd
, NULL
, zio
,
1440 is
->is_target_offset
, is
->is_size
,
1447 * This function is called when we have read all copies of the data and need
1448 * to try to find a combination of copies that gives us the right checksum.
1450 * If we pointed to any mirror vdevs, this effectively does the job of the
1451 * mirror. The mirror vdev code can't do its own job because we don't know
1452 * the checksum of each split segment individually.
1454 * We have to try every unique combination of copies of split segments, until
1455 * we find one that checksums correctly. Duplicate segment copies are first
1456 * discarded as an optimization to reduce the search space. After pruning
1457 * there will exist at most one valid combination.
1459 * When the total number of combinations is small they can all be checked.
1460 * For example, if we have 3 segments in the split, and each points to a
1461 * 2-way mirror with unique copies, we will have the following pieces of data:
1465 * ======|=====================
1466 * A | data_A_0 data_A_1
1467 * B | data_B_0 data_B_1
1468 * C | data_C_0 data_C_1
1470 * We will try the following (mirror children)^(number of splits) (2^3=8)
1471 * combinations, which is similar to bitwise-little-endian counting in
1472 * binary. In general each "digit" corresponds to a split segment, and the
1473 * base of each digit is is_children, which can be different for each
1476 * "low bit" "high bit"
1478 * data_A_0 data_B_0 data_C_0
1479 * data_A_1 data_B_0 data_C_0
1480 * data_A_0 data_B_1 data_C_0
1481 * data_A_1 data_B_1 data_C_0
1482 * data_A_0 data_B_0 data_C_1
1483 * data_A_1 data_B_0 data_C_1
1484 * data_A_0 data_B_1 data_C_1
1485 * data_A_1 data_B_1 data_C_1
1487 * Note that the split segments may be on the same or different top-level
1488 * vdevs. In either case, we try lots of combinations (see
1489 * zfs_reconstruct_indirect_segments_max). This ensures that if a mirror has
1490 * small silent errors on all of its children, we can still reconstruct the
1491 * correct data, as long as those errors are at sufficiently-separated
1492 * offsets (specifically, separated by the largest block size - default of
1493 * 128KB, but up to 16MB).
1496 vdev_indirect_reconstruct_io_done(zio_t
*zio
)
1498 indirect_vsd_t
*iv
= zio
->io_vsd
;
1499 uint64_t attempts
= 0;
1500 uint64_t attempts_max
= UINT64_MAX
;
1501 uint64_t combinations
= 1;
1503 if (zfs_reconstruct_indirect_combinations_max
> 0)
1504 attempts_max
= zfs_reconstruct_indirect_combinations_max
;
1507 * Discard duplicate copies of split segments to minimize the
1508 * number of unique combinations when attempting reconstruction.
1510 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1511 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1512 uint64_t is_copies
= 0;
1514 for (int i
= 0; i
< is
->is_children
; i
++) {
1515 if (is
->is_child
[i
].ic_data
== NULL
)
1518 for (int j
= i
+ 1; j
< is
->is_children
; j
++) {
1519 if (is
->is_child
[j
].ic_data
== NULL
)
1522 if (is
->is_child
[j
].ic_duplicate
== -1 &&
1523 abd_cmp(is
->is_child
[i
].ic_data
,
1524 is
->is_child
[j
].ic_data
) == 0) {
1525 is
->is_child
[j
].ic_duplicate
= i
;
1532 /* Reconstruction is impossible, no valid is->is_child[] */
1533 if (is_copies
== 0) {
1534 zio
->io_error
= EIO
;
1535 vdev_indirect_all_checksum_errors(zio
);
1536 zio_checksum_verified(zio
);
1540 combinations
*= is_copies
;
1544 /* copy data from splits to main zio */
1546 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1547 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1550 * If this child failed, its ic_data will be NULL.
1551 * Skip this combination.
1553 if (is
->is_child
[is
->is_good_child
].ic_data
== NULL
) {
1559 * If this child is a duplicate, its is_duplicate will
1560 * refer to the primary copy. Skip this combination.
1562 if (is
->is_child
[is
->is_good_child
].ic_duplicate
>= 0) {
1567 abd_copy_off(zio
->io_abd
,
1568 is
->is_child
[is
->is_good_child
].ic_data
,
1569 is
->is_split_offset
, 0, is
->is_size
);
1572 /* See if this checksum matches. */
1573 zio_bad_cksum_t zbc
;
1574 ret
= zio_checksum_error(zio
, &zbc
);
1576 /* Found a matching checksum. Issue repair i/os. */
1577 vdev_indirect_repair(zio
);
1578 zio_checksum_verified(zio
);
1583 * Checksum failed; try a different combination of split
1589 if (combinations
<= attempts_max
) {
1591 * There are relatively few possible combinations, so
1592 * deterministically check them all. We do this by
1593 * adding one to the first split's good_child. If it
1594 * overflows, then "carry over" to the next split
1595 * (like counting in base is_children, but each
1596 * digit can have a different base).
1598 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1599 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1600 is
->is_good_child
++;
1601 if (is
->is_good_child
< is
->is_children
) {
1605 is
->is_good_child
= 0;
1607 } else if (++attempts
< attempts_max
) {
1609 * There are too many combinations to try all of them
1610 * in a reasonable amount of time, so try a fixed
1611 * number of random combinations, after which we'll
1612 * consider the block unrecoverable.
1614 for (indirect_split_t
*is
= list_head(&iv
->iv_splits
);
1615 is
!= NULL
; is
= list_next(&iv
->iv_splits
, is
)) {
1616 int c
= spa_get_random(is
->is_children
);
1618 while (is
->is_child
[c
].ic_duplicate
>= 0)
1619 c
= (c
+ 1) % is
->is_children
;
1621 is
->is_good_child
= c
;
1626 /* All combinations failed. */
1627 zio
->io_error
= ret
;
1628 vdev_indirect_all_checksum_errors(zio
);
1629 zio_checksum_verified(zio
);
1636 vdev_indirect_io_done(zio_t
*zio
)
1638 indirect_vsd_t
*iv
= zio
->io_vsd
;
1640 if (iv
->iv_reconstruct
) {
1642 * We have read all copies of the data (e.g. from mirrors),
1643 * either because this was a scrub/resilver, or because the
1644 * one-copy read didn't checksum correctly.
1646 vdev_indirect_reconstruct_io_done(zio
);
1650 if (!iv
->iv_split_block
) {
1652 * This was not a split block, so we passed the BP down,
1653 * and the checksum was handled by the (one) child zio.
1658 zio_bad_cksum_t zbc
;
1659 int ret
= zio_checksum_error(zio
, &zbc
);
1661 zio_checksum_verified(zio
);
1666 * The checksum didn't match. Read all copies of all splits, and
1667 * then we will try to reconstruct. The next time
1668 * vdev_indirect_io_done() is called, iv_reconstruct will be set.
1670 vdev_indirect_read_all(zio
);
1672 zio_vdev_io_redone(zio
);
1675 vdev_ops_t vdev_indirect_ops
= {
1677 vdev_indirect_close
,
1679 vdev_indirect_io_start
,
1680 vdev_indirect_io_done
,
1685 vdev_indirect_remap
,
1686 VDEV_TYPE_INDIRECT
, /* name of this vdev type */
1687 B_FALSE
/* leaf vdev */
1690 #if defined(_KERNEL)
1691 EXPORT_SYMBOL(rs_alloc
);
1692 EXPORT_SYMBOL(spa_condense_fini
);
1693 EXPORT_SYMBOL(spa_start_indirect_condensing_thread
);
1694 EXPORT_SYMBOL(spa_condense_indirect_start_sync
);
1695 EXPORT_SYMBOL(spa_condense_init
);
1696 EXPORT_SYMBOL(spa_vdev_indirect_mark_obsolete
);
1697 EXPORT_SYMBOL(vdev_indirect_mark_obsolete
);
1698 EXPORT_SYMBOL(vdev_indirect_should_condense
);
1699 EXPORT_SYMBOL(vdev_indirect_sync_obsolete
);
1700 EXPORT_SYMBOL(vdev_obsolete_counts_are_precise
);
1701 EXPORT_SYMBOL(vdev_obsolete_sm_object
);
1703 module_param(zfs_condense_indirect_vdevs_enable
, int, 0644);
1704 MODULE_PARM_DESC(zfs_condense_indirect_vdevs_enable
,
1705 "Whether to attempt condensing indirect vdev mappings");
1708 module_param(zfs_condense_min_mapping_bytes
, ulong
, 0644);
1709 MODULE_PARM_DESC(zfs_condense_min_mapping_bytes
,
1710 "Minimum size of vdev mapping to condense");
1713 module_param(zfs_condense_max_obsolete_bytes
, ulong
, 0644);
1714 MODULE_PARM_DESC(zfs_condense_max_obsolete_bytes
,
1715 "Minimum size obsolete spacemap to attempt condensing");
1717 module_param(zfs_condense_indirect_commit_entry_delay_ms
, int, 0644);
1718 MODULE_PARM_DESC(zfs_condense_indirect_commit_entry_delay_ms
,
1719 "Delay while condensing vdev mapping");
1721 module_param(zfs_reconstruct_indirect_combinations_max
, int, 0644);
1722 MODULE_PARM_DESC(zfs_reconstruct_indirect_combinations_max
,
1723 "Maximum number of combinations when reconstructing split segments");