4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
22 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright (c) 2012 by Delphix. All rights reserved.
26 #include <sys/dsl_scan.h>
27 #include <sys/dsl_pool.h>
28 #include <sys/dsl_dataset.h>
29 #include <sys/dsl_prop.h>
30 #include <sys/dsl_dir.h>
31 #include <sys/dsl_synctask.h>
32 #include <sys/dnode.h>
33 #include <sys/dmu_tx.h>
34 #include <sys/dmu_objset.h>
38 #include <sys/zfs_context.h>
39 #include <sys/fs/zfs.h>
40 #include <sys/zfs_znode.h>
41 #include <sys/spa_impl.h>
42 #include <sys/vdev_impl.h>
43 #include <sys/zil_impl.h>
44 #include <sys/zio_checksum.h>
47 #include <sys/sa_impl.h>
48 #include <sys/zfeature.h>
50 #include <sys/zfs_vfsops.h>
53 typedef int (scan_cb_t
)(dsl_pool_t
*, const blkptr_t
*, const zbookmark_t
*);
55 static scan_cb_t dsl_scan_scrub_cb
;
56 static void dsl_scan_cancel_sync(void *, dmu_tx_t
*);
57 static void dsl_scan_sync_state(dsl_scan_t
*, dmu_tx_t
*tx
);
59 int zfs_top_maxinflight
= 32; /* maximum I/Os per top-level */
60 int zfs_resilver_delay
= 2; /* number of ticks to delay resilver */
61 int zfs_scrub_delay
= 4; /* number of ticks to delay scrub */
62 int zfs_scan_idle
= 50; /* idle window in clock ticks */
64 int zfs_scan_min_time_ms
= 1000; /* min millisecs to scrub per txg */
65 int zfs_free_min_time_ms
= 1000; /* min millisecs to free per txg */
66 int zfs_resilver_min_time_ms
= 3000; /* min millisecs to resilver per txg */
67 int zfs_no_scrub_io
= B_FALSE
; /* set to disable scrub i/o */
68 int zfs_no_scrub_prefetch
= B_FALSE
; /* set to disable srub prefetching */
69 enum ddt_class zfs_scrub_ddt_class_max
= DDT_CLASS_DUPLICATE
;
70 int dsl_scan_delay_completion
= B_FALSE
; /* set to delay scan completion */
72 #define DSL_SCAN_IS_SCRUB_RESILVER(scn) \
73 ((scn)->scn_phys.scn_func == POOL_SCAN_SCRUB || \
74 (scn)->scn_phys.scn_func == POOL_SCAN_RESILVER)
76 /* the order has to match pool_scan_type */
77 static scan_cb_t
*scan_funcs
[POOL_SCAN_FUNCS
] = {
79 dsl_scan_scrub_cb
, /* POOL_SCAN_SCRUB */
80 dsl_scan_scrub_cb
, /* POOL_SCAN_RESILVER */
84 dsl_scan_init(dsl_pool_t
*dp
, uint64_t txg
)
88 spa_t
*spa
= dp
->dp_spa
;
91 scn
= dp
->dp_scan
= kmem_zalloc(sizeof (dsl_scan_t
), KM_SLEEP
);
94 err
= zap_lookup(dp
->dp_meta_objset
, DMU_POOL_DIRECTORY_OBJECT
,
95 "scrub_func", sizeof (uint64_t), 1, &f
);
98 * There was an old-style scrub in progress. Restart a
99 * new-style scrub from the beginning.
101 scn
->scn_restart_txg
= txg
;
102 zfs_dbgmsg("old-style scrub was in progress; "
103 "restarting new-style scrub in txg %llu",
104 scn
->scn_restart_txg
);
107 * Load the queue obj from the old location so that it
108 * can be freed by dsl_scan_done().
110 (void) zap_lookup(dp
->dp_meta_objset
, DMU_POOL_DIRECTORY_OBJECT
,
111 "scrub_queue", sizeof (uint64_t), 1,
112 &scn
->scn_phys
.scn_queue_obj
);
114 err
= zap_lookup(dp
->dp_meta_objset
, DMU_POOL_DIRECTORY_OBJECT
,
115 DMU_POOL_SCAN
, sizeof (uint64_t), SCAN_PHYS_NUMINTS
,
122 if (scn
->scn_phys
.scn_state
== DSS_SCANNING
&&
123 spa_prev_software_version(dp
->dp_spa
) < SPA_VERSION_SCAN
) {
125 * A new-type scrub was in progress on an old
126 * pool, and the pool was accessed by old
127 * software. Restart from the beginning, since
128 * the old software may have changed the pool in
131 scn
->scn_restart_txg
= txg
;
132 zfs_dbgmsg("new-style scrub was modified "
133 "by old software; restarting in txg %llu",
134 scn
->scn_restart_txg
);
138 spa_scan_stat_init(spa
);
143 dsl_scan_fini(dsl_pool_t
*dp
)
146 kmem_free(dp
->dp_scan
, sizeof (dsl_scan_t
));
153 dsl_scan_setup_check(void *arg
, dmu_tx_t
*tx
)
155 dsl_scan_t
*scn
= dmu_tx_pool(tx
)->dp_scan
;
157 if (scn
->scn_phys
.scn_state
== DSS_SCANNING
)
164 dsl_scan_setup_sync(void *arg
, dmu_tx_t
*tx
)
166 dsl_scan_t
*scn
= dmu_tx_pool(tx
)->dp_scan
;
167 pool_scan_func_t
*funcp
= arg
;
168 dmu_object_type_t ot
= 0;
169 dsl_pool_t
*dp
= scn
->scn_dp
;
170 spa_t
*spa
= dp
->dp_spa
;
172 ASSERT(scn
->scn_phys
.scn_state
!= DSS_SCANNING
);
173 ASSERT(*funcp
> POOL_SCAN_NONE
&& *funcp
< POOL_SCAN_FUNCS
);
174 bzero(&scn
->scn_phys
, sizeof (scn
->scn_phys
));
175 scn
->scn_phys
.scn_func
= *funcp
;
176 scn
->scn_phys
.scn_state
= DSS_SCANNING
;
177 scn
->scn_phys
.scn_min_txg
= 0;
178 scn
->scn_phys
.scn_max_txg
= tx
->tx_txg
;
179 scn
->scn_phys
.scn_ddt_class_max
= DDT_CLASSES
- 1; /* the entire DDT */
180 scn
->scn_phys
.scn_start_time
= gethrestime_sec();
181 scn
->scn_phys
.scn_errors
= 0;
182 scn
->scn_phys
.scn_to_examine
= spa
->spa_root_vdev
->vdev_stat
.vs_alloc
;
183 scn
->scn_restart_txg
= 0;
184 spa_scan_stat_init(spa
);
186 if (DSL_SCAN_IS_SCRUB_RESILVER(scn
)) {
187 scn
->scn_phys
.scn_ddt_class_max
= zfs_scrub_ddt_class_max
;
189 /* rewrite all disk labels */
190 vdev_config_dirty(spa
->spa_root_vdev
);
192 if (vdev_resilver_needed(spa
->spa_root_vdev
,
193 &scn
->scn_phys
.scn_min_txg
, &scn
->scn_phys
.scn_max_txg
)) {
194 spa_event_notify(spa
, NULL
, FM_EREPORT_ZFS_RESILVER_START
);
196 spa_event_notify(spa
, NULL
, FM_EREPORT_ZFS_SCRUB_START
);
199 spa
->spa_scrub_started
= B_TRUE
;
201 * If this is an incremental scrub, limit the DDT scrub phase
202 * to just the auto-ditto class (for correctness); the rest
203 * of the scrub should go faster using top-down pruning.
205 if (scn
->scn_phys
.scn_min_txg
> TXG_INITIAL
)
206 scn
->scn_phys
.scn_ddt_class_max
= DDT_CLASS_DITTO
;
210 /* back to the generic stuff */
212 if (dp
->dp_blkstats
== NULL
) {
213 dp
->dp_blkstats
= kmem_alloc(sizeof (zfs_all_blkstats_t
),
214 KM_PUSHPAGE
| KM_NODEBUG
);
216 bzero(dp
->dp_blkstats
, sizeof (zfs_all_blkstats_t
));
218 if (spa_version(spa
) < SPA_VERSION_DSL_SCRUB
)
219 ot
= DMU_OT_ZAP_OTHER
;
221 scn
->scn_phys
.scn_queue_obj
= zap_create(dp
->dp_meta_objset
,
222 ot
? ot
: DMU_OT_SCAN_QUEUE
, DMU_OT_NONE
, 0, tx
);
224 dsl_scan_sync_state(scn
, tx
);
226 spa_history_log_internal(spa
, "scan setup", tx
,
227 "func=%u mintxg=%llu maxtxg=%llu",
228 *funcp
, scn
->scn_phys
.scn_min_txg
, scn
->scn_phys
.scn_max_txg
);
233 dsl_scan_done(dsl_scan_t
*scn
, boolean_t complete
, dmu_tx_t
*tx
)
235 static const char *old_names
[] = {
237 "scrub_ddt_bookmark",
238 "scrub_ddt_class_max",
247 dsl_pool_t
*dp
= scn
->scn_dp
;
248 spa_t
*spa
= dp
->dp_spa
;
251 /* Remove any remnants of an old-style scrub. */
252 for (i
= 0; old_names
[i
]; i
++) {
253 (void) zap_remove(dp
->dp_meta_objset
,
254 DMU_POOL_DIRECTORY_OBJECT
, old_names
[i
], tx
);
257 if (scn
->scn_phys
.scn_queue_obj
!= 0) {
258 VERIFY(0 == dmu_object_free(dp
->dp_meta_objset
,
259 scn
->scn_phys
.scn_queue_obj
, tx
));
260 scn
->scn_phys
.scn_queue_obj
= 0;
264 * If we were "restarted" from a stopped state, don't bother
265 * with anything else.
267 if (scn
->scn_phys
.scn_state
!= DSS_SCANNING
)
271 scn
->scn_phys
.scn_state
= DSS_FINISHED
;
273 scn
->scn_phys
.scn_state
= DSS_CANCELED
;
275 spa_history_log_internal(spa
, "scan done", tx
,
276 "complete=%u", complete
);
278 if (DSL_SCAN_IS_SCRUB_RESILVER(scn
)) {
279 mutex_enter(&spa
->spa_scrub_lock
);
280 while (spa
->spa_scrub_inflight
> 0) {
281 cv_wait(&spa
->spa_scrub_io_cv
,
282 &spa
->spa_scrub_lock
);
284 mutex_exit(&spa
->spa_scrub_lock
);
285 spa
->spa_scrub_started
= B_FALSE
;
286 spa
->spa_scrub_active
= B_FALSE
;
289 * If the scrub/resilver completed, update all DTLs to
290 * reflect this. Whether it succeeded or not, vacate
291 * all temporary scrub DTLs.
293 vdev_dtl_reassess(spa
->spa_root_vdev
, tx
->tx_txg
,
294 complete
? scn
->scn_phys
.scn_max_txg
: 0, B_TRUE
);
296 spa_event_notify(spa
, NULL
, scn
->scn_phys
.scn_min_txg
?
297 FM_EREPORT_ZFS_RESILVER_FINISH
:
298 FM_EREPORT_ZFS_SCRUB_FINISH
);
300 spa_errlog_rotate(spa
);
303 * We may have finished replacing a device.
304 * Let the async thread assess this and handle the detach.
306 spa_async_request(spa
, SPA_ASYNC_RESILVER_DONE
);
309 scn
->scn_phys
.scn_end_time
= gethrestime_sec();
314 dsl_scan_cancel_check(void *arg
, dmu_tx_t
*tx
)
316 dsl_scan_t
*scn
= dmu_tx_pool(tx
)->dp_scan
;
318 if (scn
->scn_phys
.scn_state
!= DSS_SCANNING
)
325 dsl_scan_cancel_sync(void *arg
, dmu_tx_t
*tx
)
327 dsl_scan_t
*scn
= dmu_tx_pool(tx
)->dp_scan
;
329 dsl_scan_done(scn
, B_FALSE
, tx
);
330 dsl_scan_sync_state(scn
, tx
);
334 dsl_scan_cancel(dsl_pool_t
*dp
)
336 return (dsl_sync_task(spa_name(dp
->dp_spa
), dsl_scan_cancel_check
,
337 dsl_scan_cancel_sync
, NULL
, 3));
340 static void dsl_scan_visitbp(blkptr_t
*bp
,
341 const zbookmark_t
*zb
, dnode_phys_t
*dnp
, arc_buf_t
*pbuf
,
342 dsl_dataset_t
*ds
, dsl_scan_t
*scn
, dmu_objset_type_t ostype
,
344 inline __attribute__((always_inline
)) static void dsl_scan_visitdnode(
345 dsl_scan_t
*, dsl_dataset_t
*ds
, dmu_objset_type_t ostype
,
346 dnode_phys_t
*dnp
, arc_buf_t
*buf
, uint64_t object
, dmu_tx_t
*tx
);
349 dsl_free(dsl_pool_t
*dp
, uint64_t txg
, const blkptr_t
*bp
)
351 zio_free(dp
->dp_spa
, txg
, bp
);
355 dsl_free_sync(zio_t
*pio
, dsl_pool_t
*dp
, uint64_t txg
, const blkptr_t
*bpp
)
357 ASSERT(dsl_pool_sync_context(dp
));
358 zio_nowait(zio_free_sync(pio
, dp
->dp_spa
, txg
, bpp
, pio
->io_flags
));
362 dsl_scan_ds_maxtxg(dsl_dataset_t
*ds
)
364 uint64_t smt
= ds
->ds_dir
->dd_pool
->dp_scan
->scn_phys
.scn_max_txg
;
365 if (dsl_dataset_is_snapshot(ds
))
366 return (MIN(smt
, ds
->ds_phys
->ds_creation_txg
));
371 dsl_scan_sync_state(dsl_scan_t
*scn
, dmu_tx_t
*tx
)
373 VERIFY0(zap_update(scn
->scn_dp
->dp_meta_objset
,
374 DMU_POOL_DIRECTORY_OBJECT
,
375 DMU_POOL_SCAN
, sizeof (uint64_t), SCAN_PHYS_NUMINTS
,
376 &scn
->scn_phys
, tx
));
380 dsl_scan_check_pause(dsl_scan_t
*scn
, const zbookmark_t
*zb
)
382 uint64_t elapsed_nanosecs
;
385 /* we never skip user/group accounting objects */
386 if (zb
&& (int64_t)zb
->zb_object
< 0)
389 if (scn
->scn_pausing
)
390 return (B_TRUE
); /* we're already pausing */
392 if (!ZB_IS_ZERO(&scn
->scn_phys
.scn_bookmark
))
393 return (B_FALSE
); /* we're resuming */
395 /* We only know how to resume from level-0 blocks. */
396 if (zb
&& zb
->zb_level
!= 0)
399 mintime
= (scn
->scn_phys
.scn_func
== POOL_SCAN_RESILVER
) ?
400 zfs_resilver_min_time_ms
: zfs_scan_min_time_ms
;
401 elapsed_nanosecs
= gethrtime() - scn
->scn_sync_start_time
;
402 if (elapsed_nanosecs
/ NANOSEC
> zfs_txg_timeout
||
403 (elapsed_nanosecs
/ MICROSEC
> mintime
&&
404 txg_sync_waiting(scn
->scn_dp
)) ||
405 spa_shutting_down(scn
->scn_dp
->dp_spa
)) {
407 dprintf("pausing at bookmark %llx/%llx/%llx/%llx\n",
408 (longlong_t
)zb
->zb_objset
,
409 (longlong_t
)zb
->zb_object
,
410 (longlong_t
)zb
->zb_level
,
411 (longlong_t
)zb
->zb_blkid
);
412 scn
->scn_phys
.scn_bookmark
= *zb
;
414 dprintf("pausing at DDT bookmark %llx/%llx/%llx/%llx\n",
415 (longlong_t
)scn
->scn_phys
.scn_ddt_bookmark
.ddb_class
,
416 (longlong_t
)scn
->scn_phys
.scn_ddt_bookmark
.ddb_type
,
417 (longlong_t
)scn
->scn_phys
.scn_ddt_bookmark
.ddb_checksum
,
418 (longlong_t
)scn
->scn_phys
.scn_ddt_bookmark
.ddb_cursor
);
419 scn
->scn_pausing
= B_TRUE
;
425 typedef struct zil_scan_arg
{
427 zil_header_t
*zsa_zh
;
432 dsl_scan_zil_block(zilog_t
*zilog
, blkptr_t
*bp
, void *arg
, uint64_t claim_txg
)
434 zil_scan_arg_t
*zsa
= arg
;
435 dsl_pool_t
*dp
= zsa
->zsa_dp
;
436 dsl_scan_t
*scn
= dp
->dp_scan
;
437 zil_header_t
*zh
= zsa
->zsa_zh
;
440 if (bp
->blk_birth
<= scn
->scn_phys
.scn_cur_min_txg
)
444 * One block ("stubby") can be allocated a long time ago; we
445 * want to visit that one because it has been allocated
446 * (on-disk) even if it hasn't been claimed (even though for
447 * scrub there's nothing to do to it).
449 if (claim_txg
== 0 && bp
->blk_birth
>= spa_first_txg(dp
->dp_spa
))
452 SET_BOOKMARK(&zb
, zh
->zh_log
.blk_cksum
.zc_word
[ZIL_ZC_OBJSET
],
453 ZB_ZIL_OBJECT
, ZB_ZIL_LEVEL
, bp
->blk_cksum
.zc_word
[ZIL_ZC_SEQ
]);
455 VERIFY(0 == scan_funcs
[scn
->scn_phys
.scn_func
](dp
, bp
, &zb
));
461 dsl_scan_zil_record(zilog_t
*zilog
, lr_t
*lrc
, void *arg
, uint64_t claim_txg
)
463 if (lrc
->lrc_txtype
== TX_WRITE
) {
464 zil_scan_arg_t
*zsa
= arg
;
465 dsl_pool_t
*dp
= zsa
->zsa_dp
;
466 dsl_scan_t
*scn
= dp
->dp_scan
;
467 zil_header_t
*zh
= zsa
->zsa_zh
;
468 lr_write_t
*lr
= (lr_write_t
*)lrc
;
469 blkptr_t
*bp
= &lr
->lr_blkptr
;
472 if (bp
->blk_birth
<= scn
->scn_phys
.scn_cur_min_txg
)
476 * birth can be < claim_txg if this record's txg is
477 * already txg sync'ed (but this log block contains
478 * other records that are not synced)
480 if (claim_txg
== 0 || bp
->blk_birth
< claim_txg
)
483 SET_BOOKMARK(&zb
, zh
->zh_log
.blk_cksum
.zc_word
[ZIL_ZC_OBJSET
],
484 lr
->lr_foid
, ZB_ZIL_LEVEL
,
485 lr
->lr_offset
/ BP_GET_LSIZE(bp
));
487 VERIFY(0 == scan_funcs
[scn
->scn_phys
.scn_func
](dp
, bp
, &zb
));
493 dsl_scan_zil(dsl_pool_t
*dp
, zil_header_t
*zh
)
495 uint64_t claim_txg
= zh
->zh_claim_txg
;
496 zil_scan_arg_t zsa
= { dp
, zh
};
500 * We only want to visit blocks that have been claimed but not yet
501 * replayed (or, in read-only mode, blocks that *would* be claimed).
503 if (claim_txg
== 0 && spa_writeable(dp
->dp_spa
))
506 zilog
= zil_alloc(dp
->dp_meta_objset
, zh
);
508 (void) zil_parse(zilog
, dsl_scan_zil_block
, dsl_scan_zil_record
, &zsa
,
516 dsl_scan_prefetch(dsl_scan_t
*scn
, arc_buf_t
*buf
, blkptr_t
*bp
,
517 uint64_t objset
, uint64_t object
, uint64_t blkid
)
520 uint32_t flags
= ARC_NOWAIT
| ARC_PREFETCH
;
522 if (zfs_no_scrub_prefetch
)
525 if (BP_IS_HOLE(bp
) || bp
->blk_birth
<= scn
->scn_phys
.scn_min_txg
||
526 (BP_GET_LEVEL(bp
) == 0 && BP_GET_TYPE(bp
) != DMU_OT_DNODE
))
529 SET_BOOKMARK(&czb
, objset
, object
, BP_GET_LEVEL(bp
), blkid
);
531 (void) arc_read(scn
->scn_zio_root
, scn
->scn_dp
->dp_spa
, bp
,
532 NULL
, NULL
, ZIO_PRIORITY_ASYNC_READ
,
533 ZIO_FLAG_CANFAIL
| ZIO_FLAG_SCAN_THREAD
, &flags
, &czb
);
537 dsl_scan_check_resume(dsl_scan_t
*scn
, const dnode_phys_t
*dnp
,
538 const zbookmark_t
*zb
)
541 * We never skip over user/group accounting objects (obj<0)
543 if (!ZB_IS_ZERO(&scn
->scn_phys
.scn_bookmark
) &&
544 (int64_t)zb
->zb_object
>= 0) {
546 * If we already visited this bp & everything below (in
547 * a prior txg sync), don't bother doing it again.
549 if (zbookmark_is_before(dnp
, zb
, &scn
->scn_phys
.scn_bookmark
))
553 * If we found the block we're trying to resume from, or
554 * we went past it to a different object, zero it out to
555 * indicate that it's OK to start checking for pausing
558 if (bcmp(zb
, &scn
->scn_phys
.scn_bookmark
, sizeof (*zb
)) == 0 ||
559 zb
->zb_object
> scn
->scn_phys
.scn_bookmark
.zb_object
) {
560 dprintf("resuming at %llx/%llx/%llx/%llx\n",
561 (longlong_t
)zb
->zb_objset
,
562 (longlong_t
)zb
->zb_object
,
563 (longlong_t
)zb
->zb_level
,
564 (longlong_t
)zb
->zb_blkid
);
565 bzero(&scn
->scn_phys
.scn_bookmark
, sizeof (*zb
));
572 * Return nonzero on i/o error.
573 * Return new buf to write out in *bufp.
575 inline __attribute__((always_inline
)) static int
576 dsl_scan_recurse(dsl_scan_t
*scn
, dsl_dataset_t
*ds
, dmu_objset_type_t ostype
,
577 dnode_phys_t
*dnp
, const blkptr_t
*bp
,
578 const zbookmark_t
*zb
, dmu_tx_t
*tx
, arc_buf_t
**bufp
)
580 dsl_pool_t
*dp
= scn
->scn_dp
;
581 int zio_flags
= ZIO_FLAG_CANFAIL
| ZIO_FLAG_SCAN_THREAD
;
584 if (BP_GET_LEVEL(bp
) > 0) {
585 uint32_t flags
= ARC_WAIT
;
588 int epb
= BP_GET_LSIZE(bp
) >> SPA_BLKPTRSHIFT
;
590 err
= arc_read(NULL
, dp
->dp_spa
, bp
, arc_getbuf_func
, bufp
,
591 ZIO_PRIORITY_ASYNC_READ
, zio_flags
, &flags
, zb
);
593 scn
->scn_phys
.scn_errors
++;
596 for (i
= 0, cbp
= (*bufp
)->b_data
; i
< epb
; i
++, cbp
++) {
597 dsl_scan_prefetch(scn
, *bufp
, cbp
, zb
->zb_objset
,
598 zb
->zb_object
, zb
->zb_blkid
* epb
+ i
);
600 for (i
= 0, cbp
= (*bufp
)->b_data
; i
< epb
; i
++, cbp
++) {
603 SET_BOOKMARK(&czb
, zb
->zb_objset
, zb
->zb_object
,
605 zb
->zb_blkid
* epb
+ i
);
606 dsl_scan_visitbp(cbp
, &czb
, dnp
,
607 *bufp
, ds
, scn
, ostype
, tx
);
609 } else if (BP_GET_TYPE(bp
) == DMU_OT_USERGROUP_USED
) {
610 uint32_t flags
= ARC_WAIT
;
612 err
= arc_read(NULL
, dp
->dp_spa
, bp
, arc_getbuf_func
, bufp
,
613 ZIO_PRIORITY_ASYNC_READ
, zio_flags
, &flags
, zb
);
615 scn
->scn_phys
.scn_errors
++;
618 } else if (BP_GET_TYPE(bp
) == DMU_OT_DNODE
) {
619 uint32_t flags
= ARC_WAIT
;
622 int epb
= BP_GET_LSIZE(bp
) >> DNODE_SHIFT
;
624 err
= arc_read(NULL
, dp
->dp_spa
, bp
, arc_getbuf_func
, bufp
,
625 ZIO_PRIORITY_ASYNC_READ
, zio_flags
, &flags
, zb
);
627 scn
->scn_phys
.scn_errors
++;
630 for (i
= 0, cdnp
= (*bufp
)->b_data
; i
< epb
; i
++, cdnp
++) {
631 for (j
= 0; j
< cdnp
->dn_nblkptr
; j
++) {
632 blkptr_t
*cbp
= &cdnp
->dn_blkptr
[j
];
633 dsl_scan_prefetch(scn
, *bufp
, cbp
,
634 zb
->zb_objset
, zb
->zb_blkid
* epb
+ i
, j
);
637 for (i
= 0, cdnp
= (*bufp
)->b_data
; i
< epb
; i
++, cdnp
++) {
638 dsl_scan_visitdnode(scn
, ds
, ostype
,
639 cdnp
, *bufp
, zb
->zb_blkid
* epb
+ i
, tx
);
642 } else if (BP_GET_TYPE(bp
) == DMU_OT_OBJSET
) {
643 uint32_t flags
= ARC_WAIT
;
646 err
= arc_read(NULL
, dp
->dp_spa
, bp
, arc_getbuf_func
, bufp
,
647 ZIO_PRIORITY_ASYNC_READ
, zio_flags
, &flags
, zb
);
649 scn
->scn_phys
.scn_errors
++;
653 osp
= (*bufp
)->b_data
;
655 dsl_scan_visitdnode(scn
, ds
, osp
->os_type
,
656 &osp
->os_meta_dnode
, *bufp
, DMU_META_DNODE_OBJECT
, tx
);
658 if (OBJSET_BUF_HAS_USERUSED(*bufp
)) {
660 * We also always visit user/group accounting
661 * objects, and never skip them, even if we are
662 * pausing. This is necessary so that the space
663 * deltas from this txg get integrated.
665 dsl_scan_visitdnode(scn
, ds
, osp
->os_type
,
666 &osp
->os_groupused_dnode
, *bufp
,
667 DMU_GROUPUSED_OBJECT
, tx
);
668 dsl_scan_visitdnode(scn
, ds
, osp
->os_type
,
669 &osp
->os_userused_dnode
, *bufp
,
670 DMU_USERUSED_OBJECT
, tx
);
677 inline __attribute__((always_inline
)) static void
678 dsl_scan_visitdnode(dsl_scan_t
*scn
, dsl_dataset_t
*ds
,
679 dmu_objset_type_t ostype
, dnode_phys_t
*dnp
, arc_buf_t
*buf
,
680 uint64_t object
, dmu_tx_t
*tx
)
684 for (j
= 0; j
< dnp
->dn_nblkptr
; j
++) {
687 SET_BOOKMARK(&czb
, ds
? ds
->ds_object
: 0, object
,
688 dnp
->dn_nlevels
- 1, j
);
689 dsl_scan_visitbp(&dnp
->dn_blkptr
[j
],
690 &czb
, dnp
, buf
, ds
, scn
, ostype
, tx
);
693 if (dnp
->dn_flags
& DNODE_FLAG_SPILL_BLKPTR
) {
695 SET_BOOKMARK(&czb
, ds
? ds
->ds_object
: 0, object
,
697 dsl_scan_visitbp(&dnp
->dn_spill
,
698 &czb
, dnp
, buf
, ds
, scn
, ostype
, tx
);
703 * The arguments are in this order because mdb can only print the
704 * first 5; we want them to be useful.
707 dsl_scan_visitbp(blkptr_t
*bp
, const zbookmark_t
*zb
,
708 dnode_phys_t
*dnp
, arc_buf_t
*pbuf
,
709 dsl_dataset_t
*ds
, dsl_scan_t
*scn
, dmu_objset_type_t ostype
,
712 dsl_pool_t
*dp
= scn
->scn_dp
;
713 arc_buf_t
*buf
= NULL
;
716 bp_toread
= kmem_alloc(sizeof (blkptr_t
), KM_PUSHPAGE
);
719 /* ASSERT(pbuf == NULL || arc_released(pbuf)); */
721 if (dsl_scan_check_pause(scn
, zb
))
724 if (dsl_scan_check_resume(scn
, dnp
, zb
))
727 if (bp
->blk_birth
== 0)
730 scn
->scn_visited_this_txg
++;
733 * This debugging is commented out to conserve stack space. This
734 * function is called recursively and the debugging addes several
735 * bytes to the stack for each call. It can be commented back in
736 * if required to debug an issue in dsl_scan_visitbp().
739 * "visiting ds=%p/%llu zb=%llx/%llx/%llx/%llx buf=%p bp=%p",
740 * ds, ds ? ds->ds_object : 0,
741 * zb->zb_objset, zb->zb_object, zb->zb_level, zb->zb_blkid,
745 if (bp
->blk_birth
<= scn
->scn_phys
.scn_cur_min_txg
)
748 if (dsl_scan_recurse(scn
, ds
, ostype
, dnp
, bp_toread
, zb
, tx
,
753 * If dsl_scan_ddt() has aready visited this block, it will have
754 * already done any translations or scrubbing, so don't call the
757 if (ddt_class_contains(dp
->dp_spa
,
758 scn
->scn_phys
.scn_ddt_class_max
, bp
)) {
764 * If this block is from the future (after cur_max_txg), then we
765 * are doing this on behalf of a deleted snapshot, and we will
766 * revisit the future block on the next pass of this dataset.
767 * Don't scan it now unless we need to because something
768 * under it was modified.
770 if (bp
->blk_birth
<= scn
->scn_phys
.scn_cur_max_txg
) {
771 scan_funcs
[scn
->scn_phys
.scn_func
](dp
, bp
, zb
);
774 (void) arc_buf_remove_ref(buf
, &buf
);
776 kmem_free(bp_toread
, sizeof(blkptr_t
));
780 dsl_scan_visit_rootbp(dsl_scan_t
*scn
, dsl_dataset_t
*ds
, blkptr_t
*bp
,
785 SET_BOOKMARK(&zb
, ds
? ds
->ds_object
: DMU_META_OBJSET
,
786 ZB_ROOT_OBJECT
, ZB_ROOT_LEVEL
, ZB_ROOT_BLKID
);
787 dsl_scan_visitbp(bp
, &zb
, NULL
, NULL
,
788 ds
, scn
, DMU_OST_NONE
, tx
);
790 dprintf_ds(ds
, "finished scan%s", "");
794 dsl_scan_ds_destroyed(dsl_dataset_t
*ds
, dmu_tx_t
*tx
)
796 dsl_pool_t
*dp
= ds
->ds_dir
->dd_pool
;
797 dsl_scan_t
*scn
= dp
->dp_scan
;
800 if (scn
->scn_phys
.scn_state
!= DSS_SCANNING
)
803 if (scn
->scn_phys
.scn_bookmark
.zb_objset
== ds
->ds_object
) {
804 if (dsl_dataset_is_snapshot(ds
)) {
805 /* Note, scn_cur_{min,max}_txg stays the same. */
806 scn
->scn_phys
.scn_bookmark
.zb_objset
=
807 ds
->ds_phys
->ds_next_snap_obj
;
808 zfs_dbgmsg("destroying ds %llu; currently traversing; "
809 "reset zb_objset to %llu",
810 (u_longlong_t
)ds
->ds_object
,
811 (u_longlong_t
)ds
->ds_phys
->ds_next_snap_obj
);
812 scn
->scn_phys
.scn_flags
|= DSF_VISIT_DS_AGAIN
;
814 SET_BOOKMARK(&scn
->scn_phys
.scn_bookmark
,
815 ZB_DESTROYED_OBJSET
, 0, 0, 0);
816 zfs_dbgmsg("destroying ds %llu; currently traversing; "
817 "reset bookmark to -1,0,0,0",
818 (u_longlong_t
)ds
->ds_object
);
820 } else if (zap_lookup_int_key(dp
->dp_meta_objset
,
821 scn
->scn_phys
.scn_queue_obj
, ds
->ds_object
, &mintxg
) == 0) {
822 ASSERT3U(ds
->ds_phys
->ds_num_children
, <=, 1);
823 VERIFY3U(0, ==, zap_remove_int(dp
->dp_meta_objset
,
824 scn
->scn_phys
.scn_queue_obj
, ds
->ds_object
, tx
));
825 if (dsl_dataset_is_snapshot(ds
)) {
827 * We keep the same mintxg; it could be >
828 * ds_creation_txg if the previous snapshot was
831 VERIFY(zap_add_int_key(dp
->dp_meta_objset
,
832 scn
->scn_phys
.scn_queue_obj
,
833 ds
->ds_phys
->ds_next_snap_obj
, mintxg
, tx
) == 0);
834 zfs_dbgmsg("destroying ds %llu; in queue; "
835 "replacing with %llu",
836 (u_longlong_t
)ds
->ds_object
,
837 (u_longlong_t
)ds
->ds_phys
->ds_next_snap_obj
);
839 zfs_dbgmsg("destroying ds %llu; in queue; removing",
840 (u_longlong_t
)ds
->ds_object
);
843 zfs_dbgmsg("destroying ds %llu; ignoring",
844 (u_longlong_t
)ds
->ds_object
);
848 * dsl_scan_sync() should be called after this, and should sync
849 * out our changed state, but just to be safe, do it here.
851 dsl_scan_sync_state(scn
, tx
);
855 dsl_scan_ds_snapshotted(dsl_dataset_t
*ds
, dmu_tx_t
*tx
)
857 dsl_pool_t
*dp
= ds
->ds_dir
->dd_pool
;
858 dsl_scan_t
*scn
= dp
->dp_scan
;
861 if (scn
->scn_phys
.scn_state
!= DSS_SCANNING
)
864 ASSERT(ds
->ds_phys
->ds_prev_snap_obj
!= 0);
866 if (scn
->scn_phys
.scn_bookmark
.zb_objset
== ds
->ds_object
) {
867 scn
->scn_phys
.scn_bookmark
.zb_objset
=
868 ds
->ds_phys
->ds_prev_snap_obj
;
869 zfs_dbgmsg("snapshotting ds %llu; currently traversing; "
870 "reset zb_objset to %llu",
871 (u_longlong_t
)ds
->ds_object
,
872 (u_longlong_t
)ds
->ds_phys
->ds_prev_snap_obj
);
873 } else if (zap_lookup_int_key(dp
->dp_meta_objset
,
874 scn
->scn_phys
.scn_queue_obj
, ds
->ds_object
, &mintxg
) == 0) {
875 VERIFY3U(0, ==, zap_remove_int(dp
->dp_meta_objset
,
876 scn
->scn_phys
.scn_queue_obj
, ds
->ds_object
, tx
));
877 VERIFY(zap_add_int_key(dp
->dp_meta_objset
,
878 scn
->scn_phys
.scn_queue_obj
,
879 ds
->ds_phys
->ds_prev_snap_obj
, mintxg
, tx
) == 0);
880 zfs_dbgmsg("snapshotting ds %llu; in queue; "
881 "replacing with %llu",
882 (u_longlong_t
)ds
->ds_object
,
883 (u_longlong_t
)ds
->ds_phys
->ds_prev_snap_obj
);
885 dsl_scan_sync_state(scn
, tx
);
889 dsl_scan_ds_clone_swapped(dsl_dataset_t
*ds1
, dsl_dataset_t
*ds2
, dmu_tx_t
*tx
)
891 dsl_pool_t
*dp
= ds1
->ds_dir
->dd_pool
;
892 dsl_scan_t
*scn
= dp
->dp_scan
;
895 if (scn
->scn_phys
.scn_state
!= DSS_SCANNING
)
898 if (scn
->scn_phys
.scn_bookmark
.zb_objset
== ds1
->ds_object
) {
899 scn
->scn_phys
.scn_bookmark
.zb_objset
= ds2
->ds_object
;
900 zfs_dbgmsg("clone_swap ds %llu; currently traversing; "
901 "reset zb_objset to %llu",
902 (u_longlong_t
)ds1
->ds_object
,
903 (u_longlong_t
)ds2
->ds_object
);
904 } else if (scn
->scn_phys
.scn_bookmark
.zb_objset
== ds2
->ds_object
) {
905 scn
->scn_phys
.scn_bookmark
.zb_objset
= ds1
->ds_object
;
906 zfs_dbgmsg("clone_swap ds %llu; currently traversing; "
907 "reset zb_objset to %llu",
908 (u_longlong_t
)ds2
->ds_object
,
909 (u_longlong_t
)ds1
->ds_object
);
912 if (zap_lookup_int_key(dp
->dp_meta_objset
, scn
->scn_phys
.scn_queue_obj
,
913 ds1
->ds_object
, &mintxg
) == 0) {
916 ASSERT3U(mintxg
, ==, ds1
->ds_phys
->ds_prev_snap_txg
);
917 ASSERT3U(mintxg
, ==, ds2
->ds_phys
->ds_prev_snap_txg
);
918 VERIFY3U(0, ==, zap_remove_int(dp
->dp_meta_objset
,
919 scn
->scn_phys
.scn_queue_obj
, ds1
->ds_object
, tx
));
920 err
= zap_add_int_key(dp
->dp_meta_objset
,
921 scn
->scn_phys
.scn_queue_obj
, ds2
->ds_object
, mintxg
, tx
);
922 VERIFY(err
== 0 || err
== EEXIST
);
924 /* Both were there to begin with */
925 VERIFY(0 == zap_add_int_key(dp
->dp_meta_objset
,
926 scn
->scn_phys
.scn_queue_obj
,
927 ds1
->ds_object
, mintxg
, tx
));
929 zfs_dbgmsg("clone_swap ds %llu; in queue; "
930 "replacing with %llu",
931 (u_longlong_t
)ds1
->ds_object
,
932 (u_longlong_t
)ds2
->ds_object
);
933 } else if (zap_lookup_int_key(dp
->dp_meta_objset
,
934 scn
->scn_phys
.scn_queue_obj
, ds2
->ds_object
, &mintxg
) == 0) {
935 ASSERT3U(mintxg
, ==, ds1
->ds_phys
->ds_prev_snap_txg
);
936 ASSERT3U(mintxg
, ==, ds2
->ds_phys
->ds_prev_snap_txg
);
937 VERIFY3U(0, ==, zap_remove_int(dp
->dp_meta_objset
,
938 scn
->scn_phys
.scn_queue_obj
, ds2
->ds_object
, tx
));
939 VERIFY(0 == zap_add_int_key(dp
->dp_meta_objset
,
940 scn
->scn_phys
.scn_queue_obj
, ds1
->ds_object
, mintxg
, tx
));
941 zfs_dbgmsg("clone_swap ds %llu; in queue; "
942 "replacing with %llu",
943 (u_longlong_t
)ds2
->ds_object
,
944 (u_longlong_t
)ds1
->ds_object
);
947 dsl_scan_sync_state(scn
, tx
);
950 struct enqueue_clones_arg
{
957 enqueue_clones_cb(dsl_pool_t
*dp
, dsl_dataset_t
*hds
, void *arg
)
959 struct enqueue_clones_arg
*eca
= arg
;
962 dsl_scan_t
*scn
= dp
->dp_scan
;
964 if (hds
->ds_dir
->dd_phys
->dd_origin_obj
!= eca
->originobj
)
967 err
= dsl_dataset_hold_obj(dp
, hds
->ds_object
, FTAG
, &ds
);
971 while (ds
->ds_phys
->ds_prev_snap_obj
!= eca
->originobj
) {
973 err
= dsl_dataset_hold_obj(dp
,
974 ds
->ds_phys
->ds_prev_snap_obj
, FTAG
, &prev
);
976 dsl_dataset_rele(ds
, FTAG
);
981 VERIFY(zap_add_int_key(dp
->dp_meta_objset
,
982 scn
->scn_phys
.scn_queue_obj
, ds
->ds_object
,
983 ds
->ds_phys
->ds_prev_snap_txg
, eca
->tx
) == 0);
984 dsl_dataset_rele(ds
, FTAG
);
989 dsl_scan_visitds(dsl_scan_t
*scn
, uint64_t dsobj
, dmu_tx_t
*tx
)
991 dsl_pool_t
*dp
= scn
->scn_dp
;
996 VERIFY3U(0, ==, dsl_dataset_hold_obj(dp
, dsobj
, FTAG
, &ds
));
998 if (dmu_objset_from_ds(ds
, &os
))
1002 * Only the ZIL in the head (non-snapshot) is valid. Even though
1003 * snapshots can have ZIL block pointers (which may be the same
1004 * BP as in the head), they must be ignored. So we traverse the
1005 * ZIL here, rather than in scan_recurse(), because the regular
1006 * snapshot block-sharing rules don't apply to it.
1008 if (DSL_SCAN_IS_SCRUB_RESILVER(scn
) && !dsl_dataset_is_snapshot(ds
))
1009 dsl_scan_zil(dp
, &os
->os_zil_header
);
1012 * Iterate over the bps in this ds.
1014 dmu_buf_will_dirty(ds
->ds_dbuf
, tx
);
1015 dsl_scan_visit_rootbp(scn
, ds
, &ds
->ds_phys
->ds_bp
, tx
);
1017 dsname
= kmem_alloc(ZFS_MAXNAMELEN
, KM_PUSHPAGE
);
1018 dsl_dataset_name(ds
, dsname
);
1019 zfs_dbgmsg("scanned dataset %llu (%s) with min=%llu max=%llu; "
1021 (longlong_t
)dsobj
, dsname
,
1022 (longlong_t
)scn
->scn_phys
.scn_cur_min_txg
,
1023 (longlong_t
)scn
->scn_phys
.scn_cur_max_txg
,
1024 (int)scn
->scn_pausing
);
1025 kmem_free(dsname
, ZFS_MAXNAMELEN
);
1027 if (scn
->scn_pausing
)
1031 * We've finished this pass over this dataset.
1035 * If we did not completely visit this dataset, do another pass.
1037 if (scn
->scn_phys
.scn_flags
& DSF_VISIT_DS_AGAIN
) {
1038 zfs_dbgmsg("incomplete pass; visiting again");
1039 scn
->scn_phys
.scn_flags
&= ~DSF_VISIT_DS_AGAIN
;
1040 VERIFY(zap_add_int_key(dp
->dp_meta_objset
,
1041 scn
->scn_phys
.scn_queue_obj
, ds
->ds_object
,
1042 scn
->scn_phys
.scn_cur_max_txg
, tx
) == 0);
1047 * Add descendent datasets to work queue.
1049 if (ds
->ds_phys
->ds_next_snap_obj
!= 0) {
1050 VERIFY(zap_add_int_key(dp
->dp_meta_objset
,
1051 scn
->scn_phys
.scn_queue_obj
, ds
->ds_phys
->ds_next_snap_obj
,
1052 ds
->ds_phys
->ds_creation_txg
, tx
) == 0);
1054 if (ds
->ds_phys
->ds_num_children
> 1) {
1055 boolean_t usenext
= B_FALSE
;
1056 if (ds
->ds_phys
->ds_next_clones_obj
!= 0) {
1059 * A bug in a previous version of the code could
1060 * cause upgrade_clones_cb() to not set
1061 * ds_next_snap_obj when it should, leading to a
1062 * missing entry. Therefore we can only use the
1063 * next_clones_obj when its count is correct.
1065 int err
= zap_count(dp
->dp_meta_objset
,
1066 ds
->ds_phys
->ds_next_clones_obj
, &count
);
1068 count
== ds
->ds_phys
->ds_num_children
- 1)
1073 VERIFY0(zap_join_key(dp
->dp_meta_objset
,
1074 ds
->ds_phys
->ds_next_clones_obj
,
1075 scn
->scn_phys
.scn_queue_obj
,
1076 ds
->ds_phys
->ds_creation_txg
, tx
));
1078 struct enqueue_clones_arg eca
;
1080 eca
.originobj
= ds
->ds_object
;
1082 VERIFY0(dmu_objset_find_dp(dp
, dp
->dp_root_dir_obj
,
1083 enqueue_clones_cb
, &eca
, DS_FIND_CHILDREN
));
1088 dsl_dataset_rele(ds
, FTAG
);
1093 enqueue_cb(dsl_pool_t
*dp
, dsl_dataset_t
*hds
, void *arg
)
1098 dsl_scan_t
*scn
= dp
->dp_scan
;
1100 err
= dsl_dataset_hold_obj(dp
, hds
->ds_object
, FTAG
, &ds
);
1104 while (ds
->ds_phys
->ds_prev_snap_obj
!= 0) {
1105 dsl_dataset_t
*prev
;
1106 err
= dsl_dataset_hold_obj(dp
, ds
->ds_phys
->ds_prev_snap_obj
,
1109 dsl_dataset_rele(ds
, FTAG
);
1114 * If this is a clone, we don't need to worry about it for now.
1116 if (prev
->ds_phys
->ds_next_snap_obj
!= ds
->ds_object
) {
1117 dsl_dataset_rele(ds
, FTAG
);
1118 dsl_dataset_rele(prev
, FTAG
);
1121 dsl_dataset_rele(ds
, FTAG
);
1125 VERIFY(zap_add_int_key(dp
->dp_meta_objset
, scn
->scn_phys
.scn_queue_obj
,
1126 ds
->ds_object
, ds
->ds_phys
->ds_prev_snap_txg
, tx
) == 0);
1127 dsl_dataset_rele(ds
, FTAG
);
1132 * Scrub/dedup interaction.
1134 * If there are N references to a deduped block, we don't want to scrub it
1135 * N times -- ideally, we should scrub it exactly once.
1137 * We leverage the fact that the dde's replication class (enum ddt_class)
1138 * is ordered from highest replication class (DDT_CLASS_DITTO) to lowest
1139 * (DDT_CLASS_UNIQUE) so that we may walk the DDT in that order.
1141 * To prevent excess scrubbing, the scrub begins by walking the DDT
1142 * to find all blocks with refcnt > 1, and scrubs each of these once.
1143 * Since there are two replication classes which contain blocks with
1144 * refcnt > 1, we scrub the highest replication class (DDT_CLASS_DITTO) first.
1145 * Finally the top-down scrub begins, only visiting blocks with refcnt == 1.
1147 * There would be nothing more to say if a block's refcnt couldn't change
1148 * during a scrub, but of course it can so we must account for changes
1149 * in a block's replication class.
1151 * Here's an example of what can occur:
1153 * If a block has refcnt > 1 during the DDT scrub phase, but has refcnt == 1
1154 * when visited during the top-down scrub phase, it will be scrubbed twice.
1155 * This negates our scrub optimization, but is otherwise harmless.
1157 * If a block has refcnt == 1 during the DDT scrub phase, but has refcnt > 1
1158 * on each visit during the top-down scrub phase, it will never be scrubbed.
1159 * To catch this, ddt_sync_entry() notifies the scrub code whenever a block's
1160 * reference class transitions to a higher level (i.e DDT_CLASS_UNIQUE to
1161 * DDT_CLASS_DUPLICATE); if it transitions from refcnt == 1 to refcnt > 1
1162 * while a scrub is in progress, it scrubs the block right then.
1165 dsl_scan_ddt(dsl_scan_t
*scn
, dmu_tx_t
*tx
)
1167 ddt_bookmark_t
*ddb
= &scn
->scn_phys
.scn_ddt_bookmark
;
1172 bzero(&dde
, sizeof (ddt_entry_t
));
1174 while ((error
= ddt_walk(scn
->scn_dp
->dp_spa
, ddb
, &dde
)) == 0) {
1177 if (ddb
->ddb_class
> scn
->scn_phys
.scn_ddt_class_max
)
1179 dprintf("visiting ddb=%llu/%llu/%llu/%llx\n",
1180 (longlong_t
)ddb
->ddb_class
,
1181 (longlong_t
)ddb
->ddb_type
,
1182 (longlong_t
)ddb
->ddb_checksum
,
1183 (longlong_t
)ddb
->ddb_cursor
);
1185 /* There should be no pending changes to the dedup table */
1186 ddt
= scn
->scn_dp
->dp_spa
->spa_ddt
[ddb
->ddb_checksum
];
1187 ASSERT(avl_first(&ddt
->ddt_tree
) == NULL
);
1189 dsl_scan_ddt_entry(scn
, ddb
->ddb_checksum
, &dde
, tx
);
1192 if (dsl_scan_check_pause(scn
, NULL
))
1196 zfs_dbgmsg("scanned %llu ddt entries with class_max = %u; pausing=%u",
1197 (longlong_t
)n
, (int)scn
->scn_phys
.scn_ddt_class_max
,
1198 (int)scn
->scn_pausing
);
1200 ASSERT(error
== 0 || error
== ENOENT
);
1201 ASSERT(error
!= ENOENT
||
1202 ddb
->ddb_class
> scn
->scn_phys
.scn_ddt_class_max
);
1207 dsl_scan_ddt_entry(dsl_scan_t
*scn
, enum zio_checksum checksum
,
1208 ddt_entry_t
*dde
, dmu_tx_t
*tx
)
1210 const ddt_key_t
*ddk
= &dde
->dde_key
;
1211 ddt_phys_t
*ddp
= dde
->dde_phys
;
1213 zbookmark_t zb
= { 0 };
1216 if (scn
->scn_phys
.scn_state
!= DSS_SCANNING
)
1219 for (p
= 0; p
< DDT_PHYS_TYPES
; p
++, ddp
++) {
1220 if (ddp
->ddp_phys_birth
== 0 ||
1221 ddp
->ddp_phys_birth
> scn
->scn_phys
.scn_cur_max_txg
)
1223 ddt_bp_create(checksum
, ddk
, ddp
, &bp
);
1225 scn
->scn_visited_this_txg
++;
1226 scan_funcs
[scn
->scn_phys
.scn_func
](scn
->scn_dp
, &bp
, &zb
);
1231 dsl_scan_visit(dsl_scan_t
*scn
, dmu_tx_t
*tx
)
1233 dsl_pool_t
*dp
= scn
->scn_dp
;
1235 zap_attribute_t
*za
;
1237 if (scn
->scn_phys
.scn_ddt_bookmark
.ddb_class
<=
1238 scn
->scn_phys
.scn_ddt_class_max
) {
1239 scn
->scn_phys
.scn_cur_min_txg
= scn
->scn_phys
.scn_min_txg
;
1240 scn
->scn_phys
.scn_cur_max_txg
= scn
->scn_phys
.scn_max_txg
;
1241 dsl_scan_ddt(scn
, tx
);
1242 if (scn
->scn_pausing
)
1246 if (scn
->scn_phys
.scn_bookmark
.zb_objset
== DMU_META_OBJSET
) {
1247 /* First do the MOS & ORIGIN */
1249 scn
->scn_phys
.scn_cur_min_txg
= scn
->scn_phys
.scn_min_txg
;
1250 scn
->scn_phys
.scn_cur_max_txg
= scn
->scn_phys
.scn_max_txg
;
1251 dsl_scan_visit_rootbp(scn
, NULL
,
1252 &dp
->dp_meta_rootbp
, tx
);
1253 spa_set_rootblkptr(dp
->dp_spa
, &dp
->dp_meta_rootbp
);
1254 if (scn
->scn_pausing
)
1257 if (spa_version(dp
->dp_spa
) < SPA_VERSION_DSL_SCRUB
) {
1258 VERIFY0(dmu_objset_find_dp(dp
, dp
->dp_root_dir_obj
,
1259 enqueue_cb
, tx
, DS_FIND_CHILDREN
));
1261 dsl_scan_visitds(scn
,
1262 dp
->dp_origin_snap
->ds_object
, tx
);
1264 ASSERT(!scn
->scn_pausing
);
1265 } else if (scn
->scn_phys
.scn_bookmark
.zb_objset
!=
1266 ZB_DESTROYED_OBJSET
) {
1268 * If we were paused, continue from here. Note if the
1269 * ds we were paused on was deleted, the zb_objset may
1270 * be -1, so we will skip this and find a new objset
1273 dsl_scan_visitds(scn
, scn
->scn_phys
.scn_bookmark
.zb_objset
, tx
);
1274 if (scn
->scn_pausing
)
1279 * In case we were paused right at the end of the ds, zero the
1280 * bookmark so we don't think that we're still trying to resume.
1282 bzero(&scn
->scn_phys
.scn_bookmark
, sizeof (zbookmark_t
));
1283 zc
= kmem_alloc(sizeof(zap_cursor_t
), KM_PUSHPAGE
);
1284 za
= kmem_alloc(sizeof(zap_attribute_t
), KM_PUSHPAGE
);
1286 /* keep pulling things out of the zap-object-as-queue */
1287 while (zap_cursor_init(zc
, dp
->dp_meta_objset
,
1288 scn
->scn_phys
.scn_queue_obj
),
1289 zap_cursor_retrieve(zc
, za
) == 0) {
1293 dsobj
= strtonum(za
->za_name
, NULL
);
1294 VERIFY3U(0, ==, zap_remove_int(dp
->dp_meta_objset
,
1295 scn
->scn_phys
.scn_queue_obj
, dsobj
, tx
));
1297 /* Set up min/max txg */
1298 VERIFY3U(0, ==, dsl_dataset_hold_obj(dp
, dsobj
, FTAG
, &ds
));
1299 if (za
->za_first_integer
!= 0) {
1300 scn
->scn_phys
.scn_cur_min_txg
=
1301 MAX(scn
->scn_phys
.scn_min_txg
,
1302 za
->za_first_integer
);
1304 scn
->scn_phys
.scn_cur_min_txg
=
1305 MAX(scn
->scn_phys
.scn_min_txg
,
1306 ds
->ds_phys
->ds_prev_snap_txg
);
1308 scn
->scn_phys
.scn_cur_max_txg
= dsl_scan_ds_maxtxg(ds
);
1309 dsl_dataset_rele(ds
, FTAG
);
1311 dsl_scan_visitds(scn
, dsobj
, tx
);
1312 zap_cursor_fini(zc
);
1313 if (scn
->scn_pausing
)
1316 zap_cursor_fini(zc
);
1318 kmem_free(za
, sizeof(zap_attribute_t
));
1319 kmem_free(zc
, sizeof(zap_cursor_t
));
1323 dsl_scan_free_should_pause(dsl_scan_t
*scn
)
1325 uint64_t elapsed_nanosecs
;
1327 elapsed_nanosecs
= gethrtime() - scn
->scn_sync_start_time
;
1328 return (elapsed_nanosecs
/ NANOSEC
> zfs_txg_timeout
||
1329 (elapsed_nanosecs
/ MICROSEC
> zfs_free_min_time_ms
&&
1330 txg_sync_waiting(scn
->scn_dp
)) ||
1331 spa_shutting_down(scn
->scn_dp
->dp_spa
));
1335 dsl_scan_free_block_cb(void *arg
, const blkptr_t
*bp
, dmu_tx_t
*tx
)
1337 dsl_scan_t
*scn
= arg
;
1339 if (!scn
->scn_is_bptree
||
1340 (BP_GET_LEVEL(bp
) == 0 && BP_GET_TYPE(bp
) != DMU_OT_OBJSET
)) {
1341 if (dsl_scan_free_should_pause(scn
))
1345 zio_nowait(zio_free_sync(scn
->scn_zio_root
, scn
->scn_dp
->dp_spa
,
1346 dmu_tx_get_txg(tx
), bp
, 0));
1347 dsl_dir_diduse_space(tx
->tx_pool
->dp_free_dir
, DD_USED_HEAD
,
1348 -bp_get_dsize_sync(scn
->scn_dp
->dp_spa
, bp
),
1349 -BP_GET_PSIZE(bp
), -BP_GET_UCSIZE(bp
), tx
);
1350 scn
->scn_visited_this_txg
++;
1355 dsl_scan_active(dsl_scan_t
*scn
)
1357 spa_t
*spa
= scn
->scn_dp
->dp_spa
;
1358 uint64_t used
= 0, comp
, uncomp
;
1360 if (spa
->spa_load_state
!= SPA_LOAD_NONE
)
1362 if (spa_shutting_down(spa
))
1365 if (scn
->scn_phys
.scn_state
== DSS_SCANNING
)
1368 if (spa_feature_is_active(spa
,
1369 &spa_feature_table
[SPA_FEATURE_ASYNC_DESTROY
])) {
1372 if (spa_version(scn
->scn_dp
->dp_spa
) >= SPA_VERSION_DEADLISTS
) {
1373 (void) bpobj_space(&scn
->scn_dp
->dp_free_bpobj
,
1374 &used
, &comp
, &uncomp
);
1380 dsl_scan_sync(dsl_pool_t
*dp
, dmu_tx_t
*tx
)
1382 dsl_scan_t
*scn
= dp
->dp_scan
;
1383 spa_t
*spa
= dp
->dp_spa
;
1387 * Check for scn_restart_txg before checking spa_load_state, so
1388 * that we can restart an old-style scan while the pool is being
1389 * imported (see dsl_scan_init).
1391 if (scn
->scn_restart_txg
!= 0 &&
1392 scn
->scn_restart_txg
<= tx
->tx_txg
) {
1393 pool_scan_func_t func
= POOL_SCAN_SCRUB
;
1394 dsl_scan_done(scn
, B_FALSE
, tx
);
1395 if (vdev_resilver_needed(spa
->spa_root_vdev
, NULL
, NULL
))
1396 func
= POOL_SCAN_RESILVER
;
1397 zfs_dbgmsg("restarting scan func=%u txg=%llu",
1399 dsl_scan_setup_sync(&func
, tx
);
1402 if (!dsl_scan_active(scn
) ||
1403 spa_sync_pass(dp
->dp_spa
) > 1)
1406 scn
->scn_visited_this_txg
= 0;
1407 scn
->scn_pausing
= B_FALSE
;
1408 scn
->scn_sync_start_time
= gethrtime();
1409 spa
->spa_scrub_active
= B_TRUE
;
1412 * First process the free list. If we pause the free, don't do
1413 * any scanning. This ensures that there is no free list when
1414 * we are scanning, so the scan code doesn't have to worry about
1417 if (spa_version(dp
->dp_spa
) >= SPA_VERSION_DEADLISTS
) {
1418 scn
->scn_is_bptree
= B_FALSE
;
1419 scn
->scn_zio_root
= zio_root(dp
->dp_spa
, NULL
,
1420 NULL
, ZIO_FLAG_MUSTSUCCEED
);
1421 err
= bpobj_iterate(&dp
->dp_free_bpobj
,
1422 dsl_scan_free_block_cb
, scn
, tx
);
1423 VERIFY3U(0, ==, zio_wait(scn
->scn_zio_root
));
1425 if (err
== 0 && spa_feature_is_active(spa
,
1426 &spa_feature_table
[SPA_FEATURE_ASYNC_DESTROY
])) {
1427 scn
->scn_is_bptree
= B_TRUE
;
1428 scn
->scn_zio_root
= zio_root(dp
->dp_spa
, NULL
,
1429 NULL
, ZIO_FLAG_MUSTSUCCEED
);
1430 err
= bptree_iterate(dp
->dp_meta_objset
,
1431 dp
->dp_bptree_obj
, B_TRUE
, dsl_scan_free_block_cb
,
1433 VERIFY0(zio_wait(scn
->scn_zio_root
));
1436 zfeature_info_t
*feat
= &spa_feature_table
1437 [SPA_FEATURE_ASYNC_DESTROY
];
1438 /* finished; deactivate async destroy feature */
1439 spa_feature_decr(spa
, feat
, tx
);
1440 ASSERT(!spa_feature_is_active(spa
, feat
));
1441 VERIFY0(zap_remove(dp
->dp_meta_objset
,
1442 DMU_POOL_DIRECTORY_OBJECT
,
1443 DMU_POOL_BPTREE_OBJ
, tx
));
1444 VERIFY0(bptree_free(dp
->dp_meta_objset
,
1445 dp
->dp_bptree_obj
, tx
));
1446 dp
->dp_bptree_obj
= 0;
1449 if (scn
->scn_visited_this_txg
) {
1450 zfs_dbgmsg("freed %llu blocks in %llums from "
1451 "free_bpobj/bptree txg %llu",
1452 (longlong_t
)scn
->scn_visited_this_txg
,
1454 (gethrtime() - scn
->scn_sync_start_time
) / MICROSEC
,
1455 (longlong_t
)tx
->tx_txg
);
1456 scn
->scn_visited_this_txg
= 0;
1458 * Re-sync the ddt so that we can further modify
1459 * it when doing bprewrite.
1461 ddt_sync(spa
, tx
->tx_txg
);
1463 if (err
== ERESTART
)
1467 if (scn
->scn_phys
.scn_state
!= DSS_SCANNING
)
1470 if (scn
->scn_phys
.scn_ddt_bookmark
.ddb_class
<=
1471 scn
->scn_phys
.scn_ddt_class_max
) {
1472 zfs_dbgmsg("doing scan sync txg %llu; "
1473 "ddt bm=%llu/%llu/%llu/%llx",
1474 (longlong_t
)tx
->tx_txg
,
1475 (longlong_t
)scn
->scn_phys
.scn_ddt_bookmark
.ddb_class
,
1476 (longlong_t
)scn
->scn_phys
.scn_ddt_bookmark
.ddb_type
,
1477 (longlong_t
)scn
->scn_phys
.scn_ddt_bookmark
.ddb_checksum
,
1478 (longlong_t
)scn
->scn_phys
.scn_ddt_bookmark
.ddb_cursor
);
1479 ASSERT(scn
->scn_phys
.scn_bookmark
.zb_objset
== 0);
1480 ASSERT(scn
->scn_phys
.scn_bookmark
.zb_object
== 0);
1481 ASSERT(scn
->scn_phys
.scn_bookmark
.zb_level
== 0);
1482 ASSERT(scn
->scn_phys
.scn_bookmark
.zb_blkid
== 0);
1484 zfs_dbgmsg("doing scan sync txg %llu; bm=%llu/%llu/%llu/%llu",
1485 (longlong_t
)tx
->tx_txg
,
1486 (longlong_t
)scn
->scn_phys
.scn_bookmark
.zb_objset
,
1487 (longlong_t
)scn
->scn_phys
.scn_bookmark
.zb_object
,
1488 (longlong_t
)scn
->scn_phys
.scn_bookmark
.zb_level
,
1489 (longlong_t
)scn
->scn_phys
.scn_bookmark
.zb_blkid
);
1492 scn
->scn_zio_root
= zio_root(dp
->dp_spa
, NULL
,
1493 NULL
, ZIO_FLAG_CANFAIL
);
1494 dsl_pool_config_enter(dp
, FTAG
);
1495 dsl_scan_visit(scn
, tx
);
1496 dsl_pool_config_exit(dp
, FTAG
);
1497 (void) zio_wait(scn
->scn_zio_root
);
1498 scn
->scn_zio_root
= NULL
;
1500 zfs_dbgmsg("visited %llu blocks in %llums",
1501 (longlong_t
)scn
->scn_visited_this_txg
,
1502 (longlong_t
)(gethrtime() - scn
->scn_sync_start_time
) / MICROSEC
);
1504 if (!scn
->scn_pausing
) {
1505 /* finished with scan. */
1506 zfs_dbgmsg("finished scan txg %llu", (longlong_t
)tx
->tx_txg
);
1507 dsl_scan_done(scn
, B_TRUE
, tx
);
1510 if (DSL_SCAN_IS_SCRUB_RESILVER(scn
)) {
1511 mutex_enter(&spa
->spa_scrub_lock
);
1512 while (spa
->spa_scrub_inflight
> 0) {
1513 cv_wait(&spa
->spa_scrub_io_cv
,
1514 &spa
->spa_scrub_lock
);
1516 mutex_exit(&spa
->spa_scrub_lock
);
1519 dsl_scan_sync_state(scn
, tx
);
1523 * This will start a new scan, or restart an existing one.
1526 dsl_resilver_restart(dsl_pool_t
*dp
, uint64_t txg
)
1530 tx
= dmu_tx_create_dd(dp
->dp_mos_dir
);
1531 VERIFY(0 == dmu_tx_assign(tx
, TXG_WAIT
));
1533 txg
= dmu_tx_get_txg(tx
);
1534 dp
->dp_scan
->scn_restart_txg
= txg
;
1537 dp
->dp_scan
->scn_restart_txg
= txg
;
1539 zfs_dbgmsg("restarting resilver txg=%llu", txg
);
1543 dsl_scan_resilvering(dsl_pool_t
*dp
)
1545 return (dp
->dp_scan
->scn_phys
.scn_state
== DSS_SCANNING
&&
1546 dp
->dp_scan
->scn_phys
.scn_func
== POOL_SCAN_RESILVER
);
1554 count_block(zfs_all_blkstats_t
*zab
, const blkptr_t
*bp
)
1559 * If we resume after a reboot, zab will be NULL; don't record
1560 * incomplete stats in that case.
1565 for (i
= 0; i
< 4; i
++) {
1566 int l
= (i
< 2) ? BP_GET_LEVEL(bp
) : DN_MAX_LEVELS
;
1567 int t
= (i
& 1) ? BP_GET_TYPE(bp
) : DMU_OT_TOTAL
;
1571 if (t
& DMU_OT_NEWTYPE
)
1574 zb
= &zab
->zab_type
[l
][t
];
1576 zb
->zb_asize
+= BP_GET_ASIZE(bp
);
1577 zb
->zb_lsize
+= BP_GET_LSIZE(bp
);
1578 zb
->zb_psize
+= BP_GET_PSIZE(bp
);
1579 zb
->zb_gangs
+= BP_COUNT_GANG(bp
);
1581 switch (BP_GET_NDVAS(bp
)) {
1583 if (DVA_GET_VDEV(&bp
->blk_dva
[0]) ==
1584 DVA_GET_VDEV(&bp
->blk_dva
[1]))
1585 zb
->zb_ditto_2_of_2_samevdev
++;
1588 equal
= (DVA_GET_VDEV(&bp
->blk_dva
[0]) ==
1589 DVA_GET_VDEV(&bp
->blk_dva
[1])) +
1590 (DVA_GET_VDEV(&bp
->blk_dva
[0]) ==
1591 DVA_GET_VDEV(&bp
->blk_dva
[2])) +
1592 (DVA_GET_VDEV(&bp
->blk_dva
[1]) ==
1593 DVA_GET_VDEV(&bp
->blk_dva
[2]));
1595 zb
->zb_ditto_2_of_3_samevdev
++;
1596 else if (equal
== 3)
1597 zb
->zb_ditto_3_of_3_samevdev
++;
1604 dsl_scan_scrub_done(zio_t
*zio
)
1606 spa_t
*spa
= zio
->io_spa
;
1608 zio_data_buf_free(zio
->io_data
, zio
->io_size
);
1610 mutex_enter(&spa
->spa_scrub_lock
);
1611 spa
->spa_scrub_inflight
--;
1612 cv_broadcast(&spa
->spa_scrub_io_cv
);
1614 if (zio
->io_error
&& (zio
->io_error
!= ECKSUM
||
1615 !(zio
->io_flags
& ZIO_FLAG_SPECULATIVE
))) {
1616 spa
->spa_dsl_pool
->dp_scan
->scn_phys
.scn_errors
++;
1618 mutex_exit(&spa
->spa_scrub_lock
);
1622 dsl_scan_scrub_cb(dsl_pool_t
*dp
,
1623 const blkptr_t
*bp
, const zbookmark_t
*zb
)
1625 dsl_scan_t
*scn
= dp
->dp_scan
;
1626 size_t size
= BP_GET_PSIZE(bp
);
1627 spa_t
*spa
= dp
->dp_spa
;
1628 uint64_t phys_birth
= BP_PHYSICAL_BIRTH(bp
);
1629 boolean_t needs_io
= B_FALSE
;
1630 int zio_flags
= ZIO_FLAG_SCAN_THREAD
| ZIO_FLAG_RAW
| ZIO_FLAG_CANFAIL
;
1631 int zio_priority
= 0;
1635 if (phys_birth
<= scn
->scn_phys
.scn_min_txg
||
1636 phys_birth
>= scn
->scn_phys
.scn_max_txg
)
1639 count_block(dp
->dp_blkstats
, bp
);
1641 ASSERT(DSL_SCAN_IS_SCRUB_RESILVER(scn
));
1642 if (scn
->scn_phys
.scn_func
== POOL_SCAN_SCRUB
) {
1643 zio_flags
|= ZIO_FLAG_SCRUB
;
1644 zio_priority
= ZIO_PRIORITY_SCRUB
;
1646 scan_delay
= zfs_scrub_delay
;
1648 ASSERT3U(scn
->scn_phys
.scn_func
, ==, POOL_SCAN_RESILVER
);
1649 zio_flags
|= ZIO_FLAG_RESILVER
;
1650 zio_priority
= ZIO_PRIORITY_RESILVER
;
1652 scan_delay
= zfs_resilver_delay
;
1655 /* If it's an intent log block, failure is expected. */
1656 if (zb
->zb_level
== ZB_ZIL_LEVEL
)
1657 zio_flags
|= ZIO_FLAG_SPECULATIVE
;
1659 for (d
= 0; d
< BP_GET_NDVAS(bp
); d
++) {
1660 vdev_t
*vd
= vdev_lookup_top(spa
,
1661 DVA_GET_VDEV(&bp
->blk_dva
[d
]));
1664 * Keep track of how much data we've examined so that
1665 * zpool(1M) status can make useful progress reports.
1667 scn
->scn_phys
.scn_examined
+= DVA_GET_ASIZE(&bp
->blk_dva
[d
]);
1668 spa
->spa_scan_pass_exam
+= DVA_GET_ASIZE(&bp
->blk_dva
[d
]);
1670 /* if it's a resilver, this may not be in the target range */
1672 if (DVA_GET_GANG(&bp
->blk_dva
[d
])) {
1674 * Gang members may be spread across multiple
1675 * vdevs, so the best estimate we have is the
1676 * scrub range, which has already been checked.
1677 * XXX -- it would be better to change our
1678 * allocation policy to ensure that all
1679 * gang members reside on the same vdev.
1683 needs_io
= vdev_dtl_contains(vd
, DTL_PARTIAL
,
1689 if (needs_io
&& !zfs_no_scrub_io
) {
1690 vdev_t
*rvd
= spa
->spa_root_vdev
;
1691 uint64_t maxinflight
= rvd
->vdev_children
* zfs_top_maxinflight
;
1692 void *data
= zio_data_buf_alloc(size
);
1694 mutex_enter(&spa
->spa_scrub_lock
);
1695 while (spa
->spa_scrub_inflight
>= maxinflight
)
1696 cv_wait(&spa
->spa_scrub_io_cv
, &spa
->spa_scrub_lock
);
1697 spa
->spa_scrub_inflight
++;
1698 mutex_exit(&spa
->spa_scrub_lock
);
1701 * If we're seeing recent (zfs_scan_idle) "important" I/Os
1702 * then throttle our workload to limit the impact of a scan.
1704 if (ddi_get_lbolt64() - spa
->spa_last_io
<= zfs_scan_idle
)
1707 zio_nowait(zio_read(NULL
, spa
, bp
, data
, size
,
1708 dsl_scan_scrub_done
, NULL
, zio_priority
,
1712 /* do not relocate this block */
1717 dsl_scan(dsl_pool_t
*dp
, pool_scan_func_t func
)
1719 spa_t
*spa
= dp
->dp_spa
;
1722 * Purge all vdev caches and probe all devices. We do this here
1723 * rather than in sync context because this requires a writer lock
1724 * on the spa_config lock, which we can't do from sync context. The
1725 * spa_scrub_reopen flag indicates that vdev_open() should not
1726 * attempt to start another scrub.
1728 spa_vdev_state_enter(spa
, SCL_NONE
);
1729 spa
->spa_scrub_reopen
= B_TRUE
;
1730 vdev_reopen(spa
->spa_root_vdev
);
1731 spa
->spa_scrub_reopen
= B_FALSE
;
1732 (void) spa_vdev_state_exit(spa
, NULL
, 0);
1734 return (dsl_sync_task(spa_name(spa
), dsl_scan_setup_check
,
1735 dsl_scan_setup_sync
, &func
, 0));
1738 #if defined(_KERNEL) && defined(HAVE_SPL)
1739 module_param(zfs_top_maxinflight
, int, 0644);
1740 MODULE_PARM_DESC(zfs_top_maxinflight
, "Max I/Os per top-level");
1742 module_param(zfs_resilver_delay
, int, 0644);
1743 MODULE_PARM_DESC(zfs_resilver_delay
, "Number of ticks to delay resilver");
1745 module_param(zfs_scrub_delay
, int, 0644);
1746 MODULE_PARM_DESC(zfs_scrub_delay
, "Number of ticks to delay scrub");
1748 module_param(zfs_scan_idle
, int, 0644);
1749 MODULE_PARM_DESC(zfs_scan_idle
, "Idle window in clock ticks");
1751 module_param(zfs_scan_min_time_ms
, int, 0644);
1752 MODULE_PARM_DESC(zfs_scan_min_time_ms
, "Min millisecs to scrub per txg");
1754 module_param(zfs_free_min_time_ms
, int, 0644);
1755 MODULE_PARM_DESC(zfs_free_min_time_ms
, "Min millisecs to free per txg");
1757 module_param(zfs_resilver_min_time_ms
, int, 0644);
1758 MODULE_PARM_DESC(zfs_resilver_min_time_ms
, "Min millisecs to resilver per txg");
1760 module_param(zfs_no_scrub_io
, int, 0644);
1761 MODULE_PARM_DESC(zfs_no_scrub_io
, "Set to disable scrub I/O");
1763 module_param(zfs_no_scrub_prefetch
, int, 0644);
1764 MODULE_PARM_DESC(zfs_no_scrub_prefetch
, "Set to disable scrub prefetching");