module/zfs/dsl_scan.c

   1 /*
   2  * CDDL HEADER START
   3  *
   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.
   7  *
   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.
  12  *
  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]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  23  */
  24
  25 #include <sys/dsl_scan.h>
  26 #include <sys/dsl_pool.h>
  27 #include <sys/dsl_dataset.h>
  28 #include <sys/dsl_prop.h>
  29 #include <sys/dsl_dir.h>
  30 #include <sys/dsl_synctask.h>
  31 #include <sys/dnode.h>
  32 #include <sys/dmu_tx.h>
  33 #include <sys/dmu_objset.h>
  34 #include <sys/arc.h>
  35 #include <sys/zap.h>
  36 #include <sys/zio.h>
  37 #include <sys/zfs_context.h>
  38 #include <sys/fs/zfs.h>
  39 #include <sys/zfs_znode.h>
  40 #include <sys/spa_impl.h>
  41 #include <sys/vdev_impl.h>
  42 #include <sys/zil_impl.h>
  43 #include <sys/zio_checksum.h>
  44 #include <sys/ddt.h>
  45 #include <sys/sa.h>
  46 #include <sys/sa_impl.h>
  47 #ifdef _KERNEL
  48 #include <sys/zfs_vfsops.h>
  49 #endif
  50
  51 typedef int (scan_cb_t)(dsl_pool_t *, const blkptr_t *, const zbookmark_t *);
  52
  53 static scan_cb_t dsl_scan_defrag_cb;
  54 static scan_cb_t dsl_scan_scrub_cb;
  55 static scan_cb_t dsl_scan_remove_cb;
  56 static dsl_syncfunc_t dsl_scan_cancel_sync;
  57 static void dsl_scan_sync_state(dsl_scan_t *, dmu_tx_t *tx);
  58
  59 int zfs_scan_min_time_ms = 1000; /* min millisecs to scrub per txg */
  60 int zfs_free_min_time_ms = 1000; /* min millisecs to free per txg */
  61 int zfs_resilver_min_time_ms = 3000; /* min millisecs to resilver per txg */
  62 boolean_t zfs_no_scrub_io = B_FALSE; /* set to disable scrub i/o */
  63 boolean_t zfs_no_scrub_prefetch = B_FALSE; /* set to disable srub prefetching */
  64 enum ddt_class zfs_scrub_ddt_class_max = DDT_CLASS_DUPLICATE;
  65 int dsl_scan_delay_completion = B_FALSE; /* set to delay scan completion */
  66
  67 #define DSL_SCAN_IS_SCRUB_RESILVER(scn) \
  68         ((scn)->scn_phys.scn_func == POOL_SCAN_SCRUB || \
  69         (scn)->scn_phys.scn_func == POOL_SCAN_RESILVER)
  70
  71 extern int zfs_txg_timeout;
  72
  73 /* the order has to match pool_scan_type */
  74 static scan_cb_t *scan_funcs[POOL_SCAN_FUNCS] = {
  75         NULL,
  76         dsl_scan_scrub_cb,      /* POOL_SCAN_SCRUB */
  77         dsl_scan_scrub_cb,      /* POOL_SCAN_RESILVER */
  78 };
  79
  80 int
  81 dsl_scan_init(dsl_pool_t *dp, uint64_t txg)
  82 {
  83         int err;
  84         dsl_scan_t *scn;
  85         spa_t *spa = dp->dp_spa;
  86         uint64_t f;
  87
  88         scn = dp->dp_scan = kmem_zalloc(sizeof (dsl_scan_t), KM_SLEEP);
  89         scn->scn_dp = dp;
  90
  91         err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
  92             "scrub_func", sizeof (uint64_t), 1, &f);
  93         if (err == 0) {
  94                 /*
  95                  * There was an old-style scrub in progress.  Restart a
  96                  * new-style scrub from the beginning.
  97                  */
  98                 scn->scn_restart_txg = txg;
  99                 zfs_dbgmsg("old-style scrub was in progress; "
 100                     "restarting new-style scrub in txg %llu",
 101                     scn->scn_restart_txg);
 102
 103                 /*
 104                  * Load the queue obj from the old location so that it
 105                  * can be freed by dsl_scan_done().
 106                  */
 107                 (void) zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 108                     "scrub_queue", sizeof (uint64_t), 1,
 109                     &scn->scn_phys.scn_queue_obj);
 110         } else {
 111                 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 112                     DMU_POOL_SCAN, sizeof (uint64_t), SCAN_PHYS_NUMINTS,
 113                     &scn->scn_phys);
 114                 if (err == ENOENT)
 115                         return (0);
 116                 else if (err)
 117                         return (err);
 118
 119                 if (scn->scn_phys.scn_state == DSS_SCANNING &&
 120                     spa_prev_software_version(dp->dp_spa) < SPA_VERSION_SCAN) {
 121                         /*
 122                          * A new-type scrub was in progress on an old
 123                          * pool, and the pool was accessed by old
 124                          * software.  Restart from the beginning, since
 125                          * the old software may have changed the pool in
 126                          * the meantime.
 127                          */
 128                         scn->scn_restart_txg = txg;
 129                         zfs_dbgmsg("new-style scrub was modified "
 130                             "by old software; restarting in txg %llu",
 131                             scn->scn_restart_txg);
 132                 }
 133         }
 134
 135         spa_scan_stat_init(spa);
 136         return (0);
 137 }
 138
 139 void
 140 dsl_scan_fini(dsl_pool_t *dp)
 141 {
 142         if (dp->dp_scan) {
 143                 kmem_free(dp->dp_scan, sizeof (dsl_scan_t));
 144                 dp->dp_scan = NULL;
 145         }
 146 }
 147
 148 /* ARGSUSED */
 149 static int
 150 dsl_scan_setup_check(void *arg1, void *arg2, dmu_tx_t *tx)
 151 {
 152         dsl_scan_t *scn = arg1;
 153
 154         if (scn->scn_phys.scn_state == DSS_SCANNING)
 155                 return (EBUSY);
 156
 157         return (0);
 158 }
 159
 160 /* ARGSUSED */
 161 static void
 162 dsl_scan_setup_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 163 {
 164         dsl_scan_t *scn = arg1;
 165         pool_scan_func_t *funcp = arg2;
 166         dmu_object_type_t ot = 0;
 167         dsl_pool_t *dp = scn->scn_dp;
 168         spa_t *spa = dp->dp_spa;
 169
 170         ASSERT(scn->scn_phys.scn_state != DSS_SCANNING);
 171         ASSERT(*funcp > POOL_SCAN_NONE && *funcp < POOL_SCAN_FUNCS);
 172         bzero(&scn->scn_phys, sizeof (scn->scn_phys));
 173         scn->scn_phys.scn_func = *funcp;
 174         scn->scn_phys.scn_state = DSS_SCANNING;
 175         scn->scn_phys.scn_min_txg = 0;
 176         scn->scn_phys.scn_max_txg = tx->tx_txg;
 177         scn->scn_phys.scn_ddt_class_max = DDT_CLASSES - 1; /* the entire DDT */
 178         scn->scn_phys.scn_start_time = gethrestime_sec();
 179         scn->scn_phys.scn_errors = 0;
 180         scn->scn_phys.scn_to_examine = spa->spa_root_vdev->vdev_stat.vs_alloc;
 181         scn->scn_restart_txg = 0;
 182         spa_scan_stat_init(spa);
 183
 184         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
 185                 scn->scn_phys.scn_ddt_class_max = zfs_scrub_ddt_class_max;
 186
 187                 /* rewrite all disk labels */
 188                 vdev_config_dirty(spa->spa_root_vdev);
 189
 190                 if (vdev_resilver_needed(spa->spa_root_vdev,
 191                     &scn->scn_phys.scn_min_txg, &scn->scn_phys.scn_max_txg)) {
 192                         spa_event_notify(spa, NULL, ESC_ZFS_RESILVER_START);
 193                 } else {
 194                         spa_event_notify(spa, NULL, ESC_ZFS_SCRUB_START);
 195                 }
 196
 197                 spa->spa_scrub_started = B_TRUE;
 198                 /*
 199                  * If this is an incremental scrub, limit the DDT scrub phase
 200                  * to just the auto-ditto class (for correctness); the rest
 201                  * of the scrub should go faster using top-down pruning.
 202                  */
 203                 if (scn->scn_phys.scn_min_txg > TXG_INITIAL)
 204                         scn->scn_phys.scn_ddt_class_max = DDT_CLASS_DITTO;
 205
 206         }
 207
 208         /* back to the generic stuff */
 209
 210         if (dp->dp_blkstats == NULL) {
 211                 dp->dp_blkstats =
 212                     kmem_alloc(sizeof (zfs_all_blkstats_t), KM_SLEEP);
 213         }
 214         bzero(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
 215
 216         if (spa_version(spa) < SPA_VERSION_DSL_SCRUB)
 217                 ot = DMU_OT_ZAP_OTHER;
 218
 219         scn->scn_phys.scn_queue_obj = zap_create(dp->dp_meta_objset,
 220             ot ? ot : DMU_OT_SCAN_QUEUE, DMU_OT_NONE, 0, tx);
 221
 222         dsl_scan_sync_state(scn, tx);
 223
 224         spa_history_log_internal(LOG_POOL_SCAN, spa, tx,
 225             "func=%u mintxg=%llu maxtxg=%llu",
 226             *funcp, scn->scn_phys.scn_min_txg, scn->scn_phys.scn_max_txg);
 227 }
 228
 229 /* ARGSUSED */
 230 static void
 231 dsl_scan_done(dsl_scan_t *scn, boolean_t complete, dmu_tx_t *tx)
 232 {
 233         static const char *old_names[] = {
 234                 "scrub_bookmark",
 235                 "scrub_ddt_bookmark",
 236                 "scrub_ddt_class_max",
 237                 "scrub_queue",
 238                 "scrub_min_txg",
 239                 "scrub_max_txg",
 240                 "scrub_func",
 241                 "scrub_errors",
 242                 NULL
 243         };
 244
 245         dsl_pool_t *dp = scn->scn_dp;
 246         spa_t *spa = dp->dp_spa;
 247         int i;
 248
 249         /* Remove any remnants of an old-style scrub. */
 250         for (i = 0; old_names[i]; i++) {
 251                 (void) zap_remove(dp->dp_meta_objset,
 252                     DMU_POOL_DIRECTORY_OBJECT, old_names[i], tx);
 253         }
 254
 255         if (scn->scn_phys.scn_queue_obj != 0) {
 256                 VERIFY(0 == dmu_object_free(dp->dp_meta_objset,
 257                     scn->scn_phys.scn_queue_obj, tx));
 258                 scn->scn_phys.scn_queue_obj = 0;
 259         }
 260
 261         /*
 262          * If we were "restarted" from a stopped state, don't bother
 263          * with anything else.
 264          */
 265         if (scn->scn_phys.scn_state != DSS_SCANNING)
 266                 return;
 267
 268         if (complete)
 269                 scn->scn_phys.scn_state = DSS_FINISHED;
 270         else
 271                 scn->scn_phys.scn_state = DSS_CANCELED;
 272
 273         spa_history_log_internal(LOG_POOL_SCAN_DONE, spa, tx,
 274             "complete=%u", complete);
 275
 276         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
 277                 mutex_enter(&spa->spa_scrub_lock);
 278                 while (spa->spa_scrub_inflight > 0) {
 279                         cv_wait(&spa->spa_scrub_io_cv,
 280                             &spa->spa_scrub_lock);
 281                 }
 282                 mutex_exit(&spa->spa_scrub_lock);
 283                 spa->spa_scrub_started = B_FALSE;
 284                 spa->spa_scrub_active = B_FALSE;
 285
 286                 /*
 287                  * If the scrub/resilver completed, update all DTLs to
 288                  * reflect this.  Whether it succeeded or not, vacate
 289                  * all temporary scrub DTLs.
 290                  */
 291                 vdev_dtl_reassess(spa->spa_root_vdev, tx->tx_txg,
 292                     complete ? scn->scn_phys.scn_max_txg : 0, B_TRUE);
 293                 if (complete) {
 294                         spa_event_notify(spa, NULL, scn->scn_phys.scn_min_txg ?
 295                             ESC_ZFS_RESILVER_FINISH : ESC_ZFS_SCRUB_FINISH);
 296                 }
 297                 spa_errlog_rotate(spa);
 298
 299                 /*
 300                  * We may have finished replacing a device.
 301                  * Let the async thread assess this and handle the detach.
 302                  */
 303                 spa_async_request(spa, SPA_ASYNC_RESILVER_DONE);
 304         }
 305
 306         scn->scn_phys.scn_end_time = gethrestime_sec();
 307 }
 308
 309 /* ARGSUSED */
 310 static int
 311 dsl_scan_cancel_check(void *arg1, void *arg2, dmu_tx_t *tx)
 312 {
 313         dsl_scan_t *scn = arg1;
 314
 315         if (scn->scn_phys.scn_state != DSS_SCANNING)
 316                 return (ENOENT);
 317         return (0);
 318 }
 319
 320 /* ARGSUSED */
 321 static void
 322 dsl_scan_cancel_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 323 {
 324         dsl_scan_t *scn = arg1;
 325
 326         dsl_scan_done(scn, B_FALSE, tx);
 327         dsl_scan_sync_state(scn, tx);
 328 }
 329
 330 int
 331 dsl_scan_cancel(dsl_pool_t *dp)
 332 {
 333         boolean_t complete = B_FALSE;
 334         int err;
 335
 336         err = dsl_sync_task_do(dp, dsl_scan_cancel_check,
 337             dsl_scan_cancel_sync, dp->dp_scan, &complete, 3);
 338         return (err);
 339 }
 340
 341 static void dsl_scan_visitbp(blkptr_t *bp,
 342     const zbookmark_t *zb, dnode_phys_t *dnp, arc_buf_t *pbuf,
 343     dsl_dataset_t *ds, dsl_scan_t *scn, dmu_objset_type_t ostype,
 344     dmu_tx_t *tx);
 345 static void dsl_scan_visitdnode(dsl_scan_t *, dsl_dataset_t *ds,
 346     dmu_objset_type_t ostype,
 347     dnode_phys_t *dnp, arc_buf_t *buf, uint64_t object, dmu_tx_t *tx);
 348
 349 void
 350 dsl_free(dsl_pool_t *dp, uint64_t txg, const blkptr_t *bp)
 351 {
 352         zio_free(dp->dp_spa, txg, bp);
 353 }
 354
 355 void
 356 dsl_free_sync(zio_t *pio, dsl_pool_t *dp, uint64_t txg, const blkptr_t *bpp)
 357 {
 358         ASSERT(dsl_pool_sync_context(dp));
 359         zio_nowait(zio_free_sync(pio, dp->dp_spa, txg, bpp, pio->io_flags));
 360 }
 361
 362 int
 363 dsl_read(zio_t *pio, spa_t *spa, const blkptr_t *bpp, arc_buf_t *pbuf,
 364     arc_done_func_t *done, void *private, int priority, int zio_flags,
 365     uint32_t *arc_flags, const zbookmark_t *zb)
 366 {
 367         return (arc_read(pio, spa, bpp, pbuf, done, private,
 368             priority, zio_flags, arc_flags, zb));
 369 }
 370
 371 int
 372 dsl_read_nolock(zio_t *pio, spa_t *spa, const blkptr_t *bpp,
 373     arc_done_func_t *done, void *private, int priority, int zio_flags,
 374     uint32_t *arc_flags, const zbookmark_t *zb)
 375 {
 376         return (arc_read_nolock(pio, spa, bpp, done, private,
 377             priority, zio_flags, arc_flags, zb));
 378 }
 379
 380 static boolean_t
 381 bookmark_is_zero(const zbookmark_t *zb)
 382 {
 383         return (zb->zb_objset == 0 && zb->zb_object == 0 &&
 384             zb->zb_level == 0 && zb->zb_blkid == 0);
 385 }
 386
 387 /* dnp is the dnode for zb1->zb_object */
 388 static boolean_t
 389 bookmark_is_before(const dnode_phys_t *dnp, const zbookmark_t *zb1,
 390     const zbookmark_t *zb2)
 391 {
 392         uint64_t zb1nextL0, zb2thisobj;
 393
 394         ASSERT(zb1->zb_objset == zb2->zb_objset);
 395         ASSERT(zb2->zb_level == 0);
 396
 397         /*
 398          * A bookmark in the deadlist is considered to be after
 399          * everything else.
 400          */
 401         if (zb2->zb_object == DMU_DEADLIST_OBJECT)
 402                 return (B_TRUE);
 403
 404         /* The objset_phys_t isn't before anything. */
 405         if (dnp == NULL)
 406                 return (B_FALSE);
 407
 408         zb1nextL0 = (zb1->zb_blkid + 1) <<
 409             ((zb1->zb_level) * (dnp->dn_indblkshift - SPA_BLKPTRSHIFT));
 410
 411         zb2thisobj = zb2->zb_object ? zb2->zb_object :
 412             zb2->zb_blkid << (DNODE_BLOCK_SHIFT - DNODE_SHIFT);
 413
 414         if (zb1->zb_object == DMU_META_DNODE_OBJECT) {
 415                 uint64_t nextobj = zb1nextL0 *
 416                     (dnp->dn_datablkszsec << SPA_MINBLOCKSHIFT) >> DNODE_SHIFT;
 417                 return (nextobj <= zb2thisobj);
 418         }
 419
 420         if (zb1->zb_object < zb2thisobj)
 421                 return (B_TRUE);
 422         if (zb1->zb_object > zb2thisobj)
 423                 return (B_FALSE);
 424         if (zb2->zb_object == DMU_META_DNODE_OBJECT)
 425                 return (B_FALSE);
 426         return (zb1nextL0 <= zb2->zb_blkid);
 427 }
 428
 429 static uint64_t
 430 dsl_scan_ds_maxtxg(dsl_dataset_t *ds)
 431 {
 432         uint64_t smt = ds->ds_dir->dd_pool->dp_scan->scn_phys.scn_max_txg;
 433         if (dsl_dataset_is_snapshot(ds))
 434                 return (MIN(smt, ds->ds_phys->ds_creation_txg));
 435         return (smt);
 436 }
 437
 438 static void
 439 dsl_scan_sync_state(dsl_scan_t *scn, dmu_tx_t *tx)
 440 {
 441         VERIFY(0 == zap_update(scn->scn_dp->dp_meta_objset,
 442             DMU_POOL_DIRECTORY_OBJECT,
 443             DMU_POOL_SCAN, sizeof (uint64_t), SCAN_PHYS_NUMINTS,
 444             &scn->scn_phys, tx));
 445 }
 446
 447 static boolean_t
 448 dsl_scan_check_pause(dsl_scan_t *scn, const zbookmark_t *zb)
 449 {
 450         uint64_t elapsed_nanosecs;
 451         int mintime;
 452
 453         /* we never skip user/group accounting objects */
 454         if (zb && (int64_t)zb->zb_object < 0)
 455                 return (B_FALSE);
 456
 457         if (scn->scn_pausing)
 458                 return (B_TRUE); /* we're already pausing */
 459
 460         if (!bookmark_is_zero(&scn->scn_phys.scn_bookmark))
 461                 return (B_FALSE); /* we're resuming */
 462
 463         /* We only know how to resume from level-0 blocks. */
 464         if (zb && zb->zb_level != 0)
 465                 return (B_FALSE);
 466
 467         mintime = (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) ?
 468             zfs_resilver_min_time_ms : zfs_scan_min_time_ms;
 469         elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
 470         if (elapsed_nanosecs / NANOSEC > zfs_txg_timeout ||
 471             (elapsed_nanosecs / MICROSEC > mintime &&
 472             txg_sync_waiting(scn->scn_dp)) ||
 473             spa_shutting_down(scn->scn_dp->dp_spa)) {
 474                 if (zb) {
 475                         dprintf("pausing at bookmark %llx/%llx/%llx/%llx\n",
 476                             (longlong_t)zb->zb_objset,
 477                             (longlong_t)zb->zb_object,
 478                             (longlong_t)zb->zb_level,
 479                             (longlong_t)zb->zb_blkid);
 480                         scn->scn_phys.scn_bookmark = *zb;
 481                 }
 482                 dprintf("pausing at DDT bookmark %llx/%llx/%llx/%llx\n",
 483                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_class,
 484                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_type,
 485                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_checksum,
 486                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_cursor);
 487                 scn->scn_pausing = B_TRUE;
 488                 return (B_TRUE);
 489         }
 490         return (B_FALSE);
 491 }
 492
 493 typedef struct zil_scan_arg {
 494         dsl_pool_t      *zsa_dp;
 495         zil_header_t    *zsa_zh;
 496 } zil_scan_arg_t;
 497
 498 /* ARGSUSED */
 499 static int
 500 dsl_scan_zil_block(zilog_t *zilog, blkptr_t *bp, void *arg, uint64_t claim_txg)
 501 {
 502         zil_scan_arg_t *zsa = arg;
 503         dsl_pool_t *dp = zsa->zsa_dp;
 504         dsl_scan_t *scn = dp->dp_scan;
 505         zil_header_t *zh = zsa->zsa_zh;
 506         zbookmark_t zb;
 507
 508         if (bp->blk_birth <= scn->scn_phys.scn_cur_min_txg)
 509                 return (0);
 510
 511         /*
 512          * One block ("stubby") can be allocated a long time ago; we
 513          * want to visit that one because it has been allocated
 514          * (on-disk) even if it hasn't been claimed (even though for
 515          * scrub there's nothing to do to it).
 516          */
 517         if (claim_txg == 0 && bp->blk_birth >= spa_first_txg(dp->dp_spa))
 518                 return (0);
 519
 520         SET_BOOKMARK(&zb, zh->zh_log.blk_cksum.zc_word[ZIL_ZC_OBJSET],
 521             ZB_ZIL_OBJECT, ZB_ZIL_LEVEL, bp->blk_cksum.zc_word[ZIL_ZC_SEQ]);
 522
 523         VERIFY(0 == scan_funcs[scn->scn_phys.scn_func](dp, bp, &zb));
 524         return (0);
 525 }
 526
 527 /* ARGSUSED */
 528 static int
 529 dsl_scan_zil_record(zilog_t *zilog, lr_t *lrc, void *arg, uint64_t claim_txg)
 530 {
 531         if (lrc->lrc_txtype == TX_WRITE) {
 532                 zil_scan_arg_t *zsa = arg;
 533                 dsl_pool_t *dp = zsa->zsa_dp;
 534                 dsl_scan_t *scn = dp->dp_scan;
 535                 zil_header_t *zh = zsa->zsa_zh;
 536                 lr_write_t *lr = (lr_write_t *)lrc;
 537                 blkptr_t *bp = &lr->lr_blkptr;
 538                 zbookmark_t zb;
 539
 540                 if (bp->blk_birth <= scn->scn_phys.scn_cur_min_txg)
 541                         return (0);
 542
 543                 /*
 544                  * birth can be < claim_txg if this record's txg is
 545                  * already txg sync'ed (but this log block contains
 546                  * other records that are not synced)
 547                  */
 548                 if (claim_txg == 0 || bp->blk_birth < claim_txg)
 549                         return (0);
 550
 551                 SET_BOOKMARK(&zb, zh->zh_log.blk_cksum.zc_word[ZIL_ZC_OBJSET],
 552                     lr->lr_foid, ZB_ZIL_LEVEL,
 553                     lr->lr_offset / BP_GET_LSIZE(bp));
 554
 555                 VERIFY(0 == scan_funcs[scn->scn_phys.scn_func](dp, bp, &zb));
 556         }
 557         return (0);
 558 }
 559
 560 static void
 561 dsl_scan_zil(dsl_pool_t *dp, zil_header_t *zh)
 562 {
 563         uint64_t claim_txg = zh->zh_claim_txg;
 564         zil_scan_arg_t zsa = { dp, zh };
 565         zilog_t *zilog;
 566
 567         /*
 568          * We only want to visit blocks that have been claimed but not yet
 569          * replayed (or, in read-only mode, blocks that *would* be claimed).
 570          */
 571         if (claim_txg == 0 && spa_writeable(dp->dp_spa))
 572                 return;
 573
 574         zilog = zil_alloc(dp->dp_meta_objset, zh);
 575
 576         (void) zil_parse(zilog, dsl_scan_zil_block, dsl_scan_zil_record, &zsa,
 577             claim_txg);
 578
 579         zil_free(zilog);
 580 }
 581
 582 /* ARGSUSED */
 583 static void
 584 dsl_scan_prefetch(dsl_scan_t *scn, arc_buf_t *buf, blkptr_t *bp,
 585     uint64_t objset, uint64_t object, uint64_t blkid)
 586 {
 587         zbookmark_t czb;
 588         uint32_t flags = ARC_NOWAIT | ARC_PREFETCH;
 589
 590         if (zfs_no_scrub_prefetch)
 591                 return;
 592
 593         if (BP_IS_HOLE(bp) || bp->blk_birth <= scn->scn_phys.scn_min_txg ||
 594             (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_DNODE))
 595                 return;
 596
 597         SET_BOOKMARK(&czb, objset, object, BP_GET_LEVEL(bp), blkid);
 598
 599         /*
 600          * XXX need to make sure all of these arc_read() prefetches are
 601          * done before setting xlateall (similar to dsl_read())
 602          */
 603         (void) arc_read(scn->scn_zio_root, scn->scn_dp->dp_spa, bp,
 604             buf, NULL, NULL, ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL,
 605             &flags, &czb);
 606 }
 607
 608 static boolean_t
 609 dsl_scan_check_resume(dsl_scan_t *scn, const dnode_phys_t *dnp,
 610     const zbookmark_t *zb)
 611 {
 612         /*
 613          * We never skip over user/group accounting objects (obj<0)
 614          */
 615         if (!bookmark_is_zero(&scn->scn_phys.scn_bookmark) &&
 616             (int64_t)zb->zb_object >= 0) {
 617                 /*
 618                  * If we already visited this bp & everything below (in
 619                  * a prior txg sync), don't bother doing it again.
 620                  */
 621                 if (bookmark_is_before(dnp, zb, &scn->scn_phys.scn_bookmark))
 622                         return (B_TRUE);
 623
 624                 /*
 625                  * If we found the block we're trying to resume from, or
 626                  * we went past it to a different object, zero it out to
 627                  * indicate that it's OK to start checking for pausing
 628                  * again.
 629                  */
 630                 if (bcmp(zb, &scn->scn_phys.scn_bookmark, sizeof (*zb)) == 0 ||
 631                     zb->zb_object > scn->scn_phys.scn_bookmark.zb_object) {
 632                         dprintf("resuming at %llx/%llx/%llx/%llx\n",
 633                             (longlong_t)zb->zb_objset,
 634                             (longlong_t)zb->zb_object,
 635                             (longlong_t)zb->zb_level,
 636                             (longlong_t)zb->zb_blkid);
 637                         bzero(&scn->scn_phys.scn_bookmark, sizeof (*zb));
 638                 }
 639         }
 640         return (B_FALSE);
 641 }
 642
 643 /*
 644  * Return nonzero on i/o error.
 645  * Return new buf to write out in *bufp.
 646  */
 647 static int
 648 dsl_scan_recurse(dsl_scan_t *scn, dsl_dataset_t *ds, dmu_objset_type_t ostype,
 649     dnode_phys_t *dnp, const blkptr_t *bp,
 650     const zbookmark_t *zb, dmu_tx_t *tx, arc_buf_t **bufp)
 651 {
 652         dsl_pool_t *dp = scn->scn_dp;
 653         int err;
 654
 655         if (BP_GET_LEVEL(bp) > 0) {
 656                 uint32_t flags = ARC_WAIT;
 657                 int i;
 658                 blkptr_t *cbp;
 659                 int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT;
 660
 661                 err = arc_read_nolock(NULL, dp->dp_spa, bp,
 662                     arc_getbuf_func, bufp,
 663                     ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
 664                 if (err) {
 665                         scn->scn_phys.scn_errors++;
 666                         return (err);
 667                 }
 668                 for (i = 0, cbp = (*bufp)->b_data; i < epb; i++, cbp++) {
 669                         dsl_scan_prefetch(scn, *bufp, cbp, zb->zb_objset,
 670                             zb->zb_object, zb->zb_blkid * epb + i);
 671                 }
 672                 for (i = 0, cbp = (*bufp)->b_data; i < epb; i++, cbp++) {
 673                         zbookmark_t czb;
 674
 675                         SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
 676                             zb->zb_level - 1,
 677                             zb->zb_blkid * epb + i);
 678                         dsl_scan_visitbp(cbp, &czb, dnp,
 679                             *bufp, ds, scn, ostype, tx);
 680                 }
 681         } else if (BP_GET_TYPE(bp) == DMU_OT_USERGROUP_USED) {
 682                 uint32_t flags = ARC_WAIT;
 683
 684                 err = arc_read_nolock(NULL, dp->dp_spa, bp,
 685                     arc_getbuf_func, bufp,
 686                     ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
 687                 if (err) {
 688                         scn->scn_phys.scn_errors++;
 689                         return (err);
 690                 }
 691         } else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) {
 692                 uint32_t flags = ARC_WAIT;
 693                 dnode_phys_t *cdnp;
 694                 int i, j;
 695                 int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT;
 696
 697                 err = arc_read_nolock(NULL, dp->dp_spa, bp,
 698                     arc_getbuf_func, bufp,
 699                     ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
 700                 if (err) {
 701                         scn->scn_phys.scn_errors++;
 702                         return (err);
 703                 }
 704                 for (i = 0, cdnp = (*bufp)->b_data; i < epb; i++, cdnp++) {
 705                         for (j = 0; j < cdnp->dn_nblkptr; j++) {
 706                                 blkptr_t *cbp = &cdnp->dn_blkptr[j];
 707                                 dsl_scan_prefetch(scn, *bufp, cbp,
 708                                     zb->zb_objset, zb->zb_blkid * epb + i, j);
 709                         }
 710                 }
 711                 for (i = 0, cdnp = (*bufp)->b_data; i < epb; i++, cdnp++) {
 712                         dsl_scan_visitdnode(scn, ds, ostype,
 713                             cdnp, *bufp, zb->zb_blkid * epb + i, tx);
 714                 }
 715
 716         } else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) {
 717                 uint32_t flags = ARC_WAIT;
 718                 objset_phys_t *osp;
 719
 720                 err = arc_read_nolock(NULL, dp->dp_spa, bp,
 721                     arc_getbuf_func, bufp,
 722                     ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
 723                 if (err) {
 724                         scn->scn_phys.scn_errors++;
 725                         return (err);
 726                 }
 727
 728                 osp = (*bufp)->b_data;
 729
 730                 if (DSL_SCAN_IS_SCRUB_RESILVER(scn))
 731                         dsl_scan_zil(dp, &osp->os_zil_header);
 732
 733                 dsl_scan_visitdnode(scn, ds, osp->os_type,
 734                     &osp->os_meta_dnode, *bufp, DMU_META_DNODE_OBJECT, tx);
 735
 736                 if (OBJSET_BUF_HAS_USERUSED(*bufp)) {
 737                         /*
 738                          * We also always visit user/group accounting
 739                          * objects, and never skip them, even if we are
 740                          * pausing.  This is necessary so that the space
 741                          * deltas from this txg get integrated.
 742                          */
 743                         dsl_scan_visitdnode(scn, ds, osp->os_type,
 744                             &osp->os_groupused_dnode, *bufp,
 745                             DMU_GROUPUSED_OBJECT, tx);
 746                         dsl_scan_visitdnode(scn, ds, osp->os_type,
 747                             &osp->os_userused_dnode, *bufp,
 748                             DMU_USERUSED_OBJECT, tx);
 749                 }
 750         }
 751
 752         return (0);
 753 }
 754
 755 static void
 756 dsl_scan_visitdnode(dsl_scan_t *scn, dsl_dataset_t *ds,
 757     dmu_objset_type_t ostype, dnode_phys_t *dnp, arc_buf_t *buf,
 758     uint64_t object, dmu_tx_t *tx)
 759 {
 760         int j;
 761
 762         for (j = 0; j < dnp->dn_nblkptr; j++) {
 763                 zbookmark_t czb;
 764
 765                 SET_BOOKMARK(&czb, ds ? ds->ds_object : 0, object,
 766                     dnp->dn_nlevels - 1, j);
 767                 dsl_scan_visitbp(&dnp->dn_blkptr[j],
 768                     &czb, dnp, buf, ds, scn, ostype, tx);
 769         }
 770
 771         if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
 772                 zbookmark_t czb;
 773                 SET_BOOKMARK(&czb, ds ? ds->ds_object : 0, object,
 774                     0, DMU_SPILL_BLKID);
 775                 dsl_scan_visitbp(&dnp->dn_spill,
 776                     &czb, dnp, buf, ds, scn, ostype, tx);
 777         }
 778 }
 779
 780 /*
 781  * The arguments are in this order because mdb can only print the
 782  * first 5; we want them to be useful.
 783  */
 784 static void
 785 dsl_scan_visitbp(blkptr_t *bp, const zbookmark_t *zb,
 786     dnode_phys_t *dnp, arc_buf_t *pbuf,
 787     dsl_dataset_t *ds, dsl_scan_t *scn, dmu_objset_type_t ostype,
 788     dmu_tx_t *tx)
 789 {
 790         dsl_pool_t *dp = scn->scn_dp;
 791         arc_buf_t *buf = NULL;
 792         blkptr_t bp_toread = *bp;
 793
 794         /* ASSERT(pbuf == NULL || arc_released(pbuf)); */
 795
 796         if (dsl_scan_check_pause(scn, zb))
 797                 return;
 798
 799         if (dsl_scan_check_resume(scn, dnp, zb))
 800                 return;
 801
 802         if (bp->blk_birth == 0)
 803                 return;
 804
 805         scn->scn_visited_this_txg++;
 806
 807         dprintf_bp(bp,
 808             "visiting ds=%p/%llu zb=%llx/%llx/%llx/%llx buf=%p bp=%p",
 809             ds, ds ? ds->ds_object : 0,
 810             zb->zb_objset, zb->zb_object, zb->zb_level, zb->zb_blkid,
 811             pbuf, bp);
 812
 813         if (bp->blk_birth <= scn->scn_phys.scn_cur_min_txg)
 814                 return;
 815
 816         if (BP_GET_TYPE(bp) != DMU_OT_USERGROUP_USED) {
 817                 /*
 818                  * For non-user-accounting blocks, we need to read the
 819                  * new bp (from a deleted snapshot, found in
 820                  * check_existing_xlation).  If we used the old bp,
 821                  * pointers inside this block from before we resumed
 822                  * would be untranslated.
 823                  *
 824                  * For user-accounting blocks, we need to read the old
 825                  * bp, because we will apply the entire space delta to
 826                  * it (original untranslated -> translations from
 827                  * deleted snap -> now).
 828                  */
 829                 bp_toread = *bp;
 830         }
 831
 832         if (dsl_scan_recurse(scn, ds, ostype, dnp, &bp_toread, zb, tx,
 833             &buf) != 0)
 834                 return;
 835
 836         /*
 837          * If dsl_scan_ddt() has aready visited this block, it will have
 838          * already done any translations or scrubbing, so don't call the
 839          * callback again.
 840          */
 841         if (ddt_class_contains(dp->dp_spa,
 842             scn->scn_phys.scn_ddt_class_max, bp)) {
 843                 ASSERT(buf == NULL);
 844                 return;
 845         }
 846
 847         /*
 848          * If this block is from the future (after cur_max_txg), then we
 849          * are doing this on behalf of a deleted snapshot, and we will
 850          * revisit the future block on the next pass of this dataset.
 851          * Don't scan it now unless we need to because something
 852          * under it was modified.
 853          */
 854         if (bp->blk_birth <= scn->scn_phys.scn_cur_max_txg) {
 855                 scan_funcs[scn->scn_phys.scn_func](dp, bp, zb);
 856         }
 857         if (buf)
 858                 (void) arc_buf_remove_ref(buf, &buf);
 859 }
 860
 861 static void
 862 dsl_scan_visit_rootbp(dsl_scan_t *scn, dsl_dataset_t *ds, blkptr_t *bp,
 863     dmu_tx_t *tx)
 864 {
 865         zbookmark_t zb;
 866
 867         SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
 868             ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
 869         dsl_scan_visitbp(bp, &zb, NULL, NULL,
 870             ds, scn, DMU_OST_NONE, tx);
 871
 872         dprintf_ds(ds, "finished scan%s", "");
 873 }
 874
 875 void
 876 dsl_scan_ds_destroyed(dsl_dataset_t *ds, dmu_tx_t *tx)
 877 {
 878         dsl_pool_t *dp = ds->ds_dir->dd_pool;
 879         dsl_scan_t *scn = dp->dp_scan;
 880         uint64_t mintxg;
 881
 882         if (scn->scn_phys.scn_state != DSS_SCANNING)
 883                 return;
 884
 885         if (scn->scn_phys.scn_bookmark.zb_objset == ds->ds_object) {
 886                 if (dsl_dataset_is_snapshot(ds)) {
 887                         /* Note, scn_cur_{min,max}_txg stays the same. */
 888                         scn->scn_phys.scn_bookmark.zb_objset =
 889                             ds->ds_phys->ds_next_snap_obj;
 890                         zfs_dbgmsg("destroying ds %llu; currently traversing; "
 891                             "reset zb_objset to %llu",
 892                             (u_longlong_t)ds->ds_object,
 893                             (u_longlong_t)ds->ds_phys->ds_next_snap_obj);
 894                         scn->scn_phys.scn_flags |= DSF_VISIT_DS_AGAIN;
 895                 } else {
 896                         SET_BOOKMARK(&scn->scn_phys.scn_bookmark,
 897                             ZB_DESTROYED_OBJSET, 0, 0, 0);
 898                         zfs_dbgmsg("destroying ds %llu; currently traversing; "
 899                             "reset bookmark to -1,0,0,0",
 900                             (u_longlong_t)ds->ds_object);
 901                 }
 902         } else if (zap_lookup_int_key(dp->dp_meta_objset,
 903             scn->scn_phys.scn_queue_obj, ds->ds_object, &mintxg) == 0) {
 904                 ASSERT3U(ds->ds_phys->ds_num_children, <=, 1);
 905                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 906                     scn->scn_phys.scn_queue_obj, ds->ds_object, tx));
 907                 if (dsl_dataset_is_snapshot(ds)) {
 908                         /*
 909                          * We keep the same mintxg; it could be >
 910                          * ds_creation_txg if the previous snapshot was
 911                          * deleted too.
 912                          */
 913                         VERIFY(zap_add_int_key(dp->dp_meta_objset,
 914                             scn->scn_phys.scn_queue_obj,
 915                             ds->ds_phys->ds_next_snap_obj, mintxg, tx) == 0);
 916                         zfs_dbgmsg("destroying ds %llu; in queue; "
 917                             "replacing with %llu",
 918                             (u_longlong_t)ds->ds_object,
 919                             (u_longlong_t)ds->ds_phys->ds_next_snap_obj);
 920                 } else {
 921                         zfs_dbgmsg("destroying ds %llu; in queue; removing",
 922                             (u_longlong_t)ds->ds_object);
 923                 }
 924         } else {
 925                 zfs_dbgmsg("destroying ds %llu; ignoring",
 926                     (u_longlong_t)ds->ds_object);
 927         }
 928
 929         /*
 930          * dsl_scan_sync() should be called after this, and should sync
 931          * out our changed state, but just to be safe, do it here.
 932          */
 933         dsl_scan_sync_state(scn, tx);
 934 }
 935
 936 void
 937 dsl_scan_ds_snapshotted(dsl_dataset_t *ds, dmu_tx_t *tx)
 938 {
 939         dsl_pool_t *dp = ds->ds_dir->dd_pool;
 940         dsl_scan_t *scn = dp->dp_scan;
 941         uint64_t mintxg;
 942
 943         if (scn->scn_phys.scn_state != DSS_SCANNING)
 944                 return;
 945
 946         ASSERT(ds->ds_phys->ds_prev_snap_obj != 0);
 947
 948         if (scn->scn_phys.scn_bookmark.zb_objset == ds->ds_object) {
 949                 scn->scn_phys.scn_bookmark.zb_objset =
 950                     ds->ds_phys->ds_prev_snap_obj;
 951                 zfs_dbgmsg("snapshotting ds %llu; currently traversing; "
 952                     "reset zb_objset to %llu",
 953                     (u_longlong_t)ds->ds_object,
 954                     (u_longlong_t)ds->ds_phys->ds_prev_snap_obj);
 955         } else if (zap_lookup_int_key(dp->dp_meta_objset,
 956             scn->scn_phys.scn_queue_obj, ds->ds_object, &mintxg) == 0) {
 957                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 958                     scn->scn_phys.scn_queue_obj, ds->ds_object, tx));
 959                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
 960                     scn->scn_phys.scn_queue_obj,
 961                     ds->ds_phys->ds_prev_snap_obj, mintxg, tx) == 0);
 962                 zfs_dbgmsg("snapshotting ds %llu; in queue; "
 963                     "replacing with %llu",
 964                     (u_longlong_t)ds->ds_object,
 965                     (u_longlong_t)ds->ds_phys->ds_prev_snap_obj);
 966         }
 967         dsl_scan_sync_state(scn, tx);
 968 }
 969
 970 void
 971 dsl_scan_ds_clone_swapped(dsl_dataset_t *ds1, dsl_dataset_t *ds2, dmu_tx_t *tx)
 972 {
 973         dsl_pool_t *dp = ds1->ds_dir->dd_pool;
 974         dsl_scan_t *scn = dp->dp_scan;
 975         uint64_t mintxg;
 976
 977         if (scn->scn_phys.scn_state != DSS_SCANNING)
 978                 return;
 979
 980         if (scn->scn_phys.scn_bookmark.zb_objset == ds1->ds_object) {
 981                 scn->scn_phys.scn_bookmark.zb_objset = ds2->ds_object;
 982                 zfs_dbgmsg("clone_swap ds %llu; currently traversing; "
 983                     "reset zb_objset to %llu",
 984                     (u_longlong_t)ds1->ds_object,
 985                     (u_longlong_t)ds2->ds_object);
 986         } else if (scn->scn_phys.scn_bookmark.zb_objset == ds2->ds_object) {
 987                 scn->scn_phys.scn_bookmark.zb_objset = ds1->ds_object;
 988                 zfs_dbgmsg("clone_swap ds %llu; currently traversing; "
 989                     "reset zb_objset to %llu",
 990                     (u_longlong_t)ds2->ds_object,
 991                     (u_longlong_t)ds1->ds_object);
 992         }
 993
 994         if (zap_lookup_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
 995             ds1->ds_object, &mintxg) == 0) {
 996                 int err;
 997
 998                 ASSERT3U(mintxg, ==, ds1->ds_phys->ds_prev_snap_txg);
 999                 ASSERT3U(mintxg, ==, ds2->ds_phys->ds_prev_snap_txg);
1000                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
1001                     scn->scn_phys.scn_queue_obj, ds1->ds_object, tx));
1002                 err = zap_add_int_key(dp->dp_meta_objset,
1003                     scn->scn_phys.scn_queue_obj, ds2->ds_object, mintxg, tx);
1004                 VERIFY(err == 0 || err == EEXIST);
1005                 if (err == EEXIST) {
1006                         /* Both were there to begin with */
1007                         VERIFY(0 == zap_add_int_key(dp->dp_meta_objset,
1008                             scn->scn_phys.scn_queue_obj,
1009                             ds1->ds_object, mintxg, tx));
1010                 }
1011                 zfs_dbgmsg("clone_swap ds %llu; in queue; "
1012                     "replacing with %llu",
1013                     (u_longlong_t)ds1->ds_object,
1014                     (u_longlong_t)ds2->ds_object);
1015         } else if (zap_lookup_int_key(dp->dp_meta_objset,
1016             scn->scn_phys.scn_queue_obj, ds2->ds_object, &mintxg) == 0) {
1017                 ASSERT3U(mintxg, ==, ds1->ds_phys->ds_prev_snap_txg);
1018                 ASSERT3U(mintxg, ==, ds2->ds_phys->ds_prev_snap_txg);
1019                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
1020                     scn->scn_phys.scn_queue_obj, ds2->ds_object, tx));
1021                 VERIFY(0 == zap_add_int_key(dp->dp_meta_objset,
1022                     scn->scn_phys.scn_queue_obj, ds1->ds_object, mintxg, tx));
1023                 zfs_dbgmsg("clone_swap ds %llu; in queue; "
1024                     "replacing with %llu",
1025                     (u_longlong_t)ds2->ds_object,
1026                     (u_longlong_t)ds1->ds_object);
1027         }
1028
1029         dsl_scan_sync_state(scn, tx);
1030 }
1031
1032 struct enqueue_clones_arg {
1033         dmu_tx_t *tx;
1034         uint64_t originobj;
1035 };
1036
1037 /* ARGSUSED */
1038 static int
1039 enqueue_clones_cb(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
1040 {
1041         struct enqueue_clones_arg *eca = arg;
1042         dsl_dataset_t *ds;
1043         int err;
1044         dsl_pool_t *dp = spa->spa_dsl_pool;
1045         dsl_scan_t *scn = dp->dp_scan;
1046
1047         err = dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds);
1048         if (err)
1049                 return (err);
1050
1051         if (ds->ds_dir->dd_phys->dd_origin_obj == eca->originobj) {
1052                 while (ds->ds_phys->ds_prev_snap_obj != eca->originobj) {
1053                         dsl_dataset_t *prev;
1054                         err = dsl_dataset_hold_obj(dp,
1055                             ds->ds_phys->ds_prev_snap_obj, FTAG, &prev);
1056
1057                         dsl_dataset_rele(ds, FTAG);
1058                         if (err)
1059                                 return (err);
1060                         ds = prev;
1061                 }
1062                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
1063                     scn->scn_phys.scn_queue_obj, ds->ds_object,
1064                     ds->ds_phys->ds_prev_snap_txg, eca->tx) == 0);
1065         }
1066         dsl_dataset_rele(ds, FTAG);
1067         return (0);
1068 }
1069
1070 static void
1071 dsl_scan_visitds(dsl_scan_t *scn, uint64_t dsobj, dmu_tx_t *tx)
1072 {
1073         dsl_pool_t *dp = scn->scn_dp;
1074         dsl_dataset_t *ds;
1075
1076         VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
1077
1078         /*
1079          * Iterate over the bps in this ds.
1080          */
1081         dmu_buf_will_dirty(ds->ds_dbuf, tx);
1082         dsl_scan_visit_rootbp(scn, ds, &ds->ds_phys->ds_bp, tx);
1083
1084         char *dsname = kmem_alloc(ZFS_MAXNAMELEN, KM_SLEEP);
1085         dsl_dataset_name(ds, dsname);
1086         zfs_dbgmsg("scanned dataset %llu (%s) with min=%llu max=%llu; "
1087             "pausing=%u",
1088             (longlong_t)dsobj, dsname,
1089             (longlong_t)scn->scn_phys.scn_cur_min_txg,
1090             (longlong_t)scn->scn_phys.scn_cur_max_txg,
1091             (int)scn->scn_pausing);
1092         kmem_free(dsname, ZFS_MAXNAMELEN);
1093
1094         if (scn->scn_pausing)
1095                 goto out;
1096
1097         /*
1098          * We've finished this pass over this dataset.
1099          */
1100
1101         /*
1102          * If we did not completely visit this dataset, do another pass.
1103          */
1104         if (scn->scn_phys.scn_flags & DSF_VISIT_DS_AGAIN) {
1105                 zfs_dbgmsg("incomplete pass; visiting again");
1106                 scn->scn_phys.scn_flags &= ~DSF_VISIT_DS_AGAIN;
1107                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
1108                     scn->scn_phys.scn_queue_obj, ds->ds_object,
1109                     scn->scn_phys.scn_cur_max_txg, tx) == 0);
1110                 goto out;
1111         }
1112
1113         /*
1114          * Add descendent datasets to work queue.
1115          */
1116         if (ds->ds_phys->ds_next_snap_obj != 0) {
1117                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
1118                     scn->scn_phys.scn_queue_obj, ds->ds_phys->ds_next_snap_obj,
1119                     ds->ds_phys->ds_creation_txg, tx) == 0);
1120         }
1121         if (ds->ds_phys->ds_num_children > 1) {
1122                 boolean_t usenext = B_FALSE;
1123                 if (ds->ds_phys->ds_next_clones_obj != 0) {
1124                         uint64_t count;
1125                         /*
1126                          * A bug in a previous version of the code could
1127                          * cause upgrade_clones_cb() to not set
1128                          * ds_next_snap_obj when it should, leading to a
1129                          * missing entry.  Therefore we can only use the
1130                          * next_clones_obj when its count is correct.
1131                          */
1132                         int err = zap_count(dp->dp_meta_objset,
1133                             ds->ds_phys->ds_next_clones_obj, &count);
1134                         if (err == 0 &&
1135                             count == ds->ds_phys->ds_num_children - 1)
1136                                 usenext = B_TRUE;
1137                 }
1138
1139                 if (usenext) {
1140                         VERIFY(zap_join_key(dp->dp_meta_objset,
1141                             ds->ds_phys->ds_next_clones_obj,
1142                             scn->scn_phys.scn_queue_obj,
1143                             ds->ds_phys->ds_creation_txg, tx) == 0);
1144                 } else {
1145                         struct enqueue_clones_arg eca;
1146                         eca.tx = tx;
1147                         eca.originobj = ds->ds_object;
1148
1149                         (void) dmu_objset_find_spa(ds->ds_dir->dd_pool->dp_spa,
1150                             NULL, enqueue_clones_cb, &eca, DS_FIND_CHILDREN);
1151                 }
1152         }
1153
1154 out:
1155         dsl_dataset_rele(ds, FTAG);
1156 }
1157
1158 /* ARGSUSED */
1159 static int
1160 enqueue_cb(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
1161 {
1162         dmu_tx_t *tx = arg;
1163         dsl_dataset_t *ds;
1164         int err;
1165         dsl_pool_t *dp = spa->spa_dsl_pool;
1166         dsl_scan_t *scn = dp->dp_scan;
1167
1168         err = dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds);
1169         if (err)
1170                 return (err);
1171
1172         while (ds->ds_phys->ds_prev_snap_obj != 0) {
1173                 dsl_dataset_t *prev;
1174                 err = dsl_dataset_hold_obj(dp, ds->ds_phys->ds_prev_snap_obj,
1175                     FTAG, &prev);
1176                 if (err) {
1177                         dsl_dataset_rele(ds, FTAG);
1178                         return (err);
1179                 }
1180
1181                 /*
1182                  * If this is a clone, we don't need to worry about it for now.
1183                  */
1184                 if (prev->ds_phys->ds_next_snap_obj != ds->ds_object) {
1185                         dsl_dataset_rele(ds, FTAG);
1186                         dsl_dataset_rele(prev, FTAG);
1187                         return (0);
1188                 }
1189                 dsl_dataset_rele(ds, FTAG);
1190                 ds = prev;
1191         }
1192
1193         VERIFY(zap_add_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
1194             ds->ds_object, ds->ds_phys->ds_prev_snap_txg, tx) == 0);
1195         dsl_dataset_rele(ds, FTAG);
1196         return (0);
1197 }
1198
1199 /*
1200  * Scrub/dedup interaction.
1201  *
1202  * If there are N references to a deduped block, we don't want to scrub it
1203  * N times -- ideally, we should scrub it exactly once.
1204  *
1205  * We leverage the fact that the dde's replication class (enum ddt_class)
1206  * is ordered from highest replication class (DDT_CLASS_DITTO) to lowest
1207  * (DDT_CLASS_UNIQUE) so that we may walk the DDT in that order.
1208  *
1209  * To prevent excess scrubbing, the scrub begins by walking the DDT
1210  * to find all blocks with refcnt > 1, and scrubs each of these once.
1211  * Since there are two replication classes which contain blocks with
1212  * refcnt > 1, we scrub the highest replication class (DDT_CLASS_DITTO) first.
1213  * Finally the top-down scrub begins, only visiting blocks with refcnt == 1.
1214  *
1215  * There would be nothing more to say if a block's refcnt couldn't change
1216  * during a scrub, but of course it can so we must account for changes
1217  * in a block's replication class.
1218  *
1219  * Here's an example of what can occur:
1220  *
1221  * If a block has refcnt > 1 during the DDT scrub phase, but has refcnt == 1
1222  * when visited during the top-down scrub phase, it will be scrubbed twice.
1223  * This negates our scrub optimization, but is otherwise harmless.
1224  *
1225  * If a block has refcnt == 1 during the DDT scrub phase, but has refcnt > 1
1226  * on each visit during the top-down scrub phase, it will never be scrubbed.
1227  * To catch this, ddt_sync_entry() notifies the scrub code whenever a block's
1228  * reference class transitions to a higher level (i.e DDT_CLASS_UNIQUE to
1229  * DDT_CLASS_DUPLICATE); if it transitions from refcnt == 1 to refcnt > 1
1230  * while a scrub is in progress, it scrubs the block right then.
1231  */
1232 static void
1233 dsl_scan_ddt(dsl_scan_t *scn, dmu_tx_t *tx)
1234 {
1235         ddt_bookmark_t *ddb = &scn->scn_phys.scn_ddt_bookmark;
1236         ddt_entry_t dde = { 0 };
1237         int error;
1238         uint64_t n = 0;
1239
1240         while ((error = ddt_walk(scn->scn_dp->dp_spa, ddb, &dde)) == 0) {
1241                 ddt_t *ddt;
1242
1243                 if (ddb->ddb_class > scn->scn_phys.scn_ddt_class_max)
1244                         break;
1245                 dprintf("visiting ddb=%llu/%llu/%llu/%llx\n",
1246                     (longlong_t)ddb->ddb_class,
1247                     (longlong_t)ddb->ddb_type,
1248                     (longlong_t)ddb->ddb_checksum,
1249                     (longlong_t)ddb->ddb_cursor);
1250
1251                 /* There should be no pending changes to the dedup table */
1252                 ddt = scn->scn_dp->dp_spa->spa_ddt[ddb->ddb_checksum];
1253                 ASSERT(avl_first(&ddt->ddt_tree) == NULL);
1254
1255                 dsl_scan_ddt_entry(scn, ddb->ddb_checksum, &dde, tx);
1256                 n++;
1257
1258                 if (dsl_scan_check_pause(scn, NULL))
1259                         break;
1260         }
1261
1262         zfs_dbgmsg("scanned %llu ddt entries with class_max = %u; pausing=%u",
1263             (longlong_t)n, (int)scn->scn_phys.scn_ddt_class_max,
1264             (int)scn->scn_pausing);
1265
1266         ASSERT(error == 0 || error == ENOENT);
1267         ASSERT(error != ENOENT ||
1268             ddb->ddb_class > scn->scn_phys.scn_ddt_class_max);
1269 }
1270
1271 /* ARGSUSED */
1272 void
1273 dsl_scan_ddt_entry(dsl_scan_t *scn, enum zio_checksum checksum,
1274     ddt_entry_t *dde, dmu_tx_t *tx)
1275 {
1276         const ddt_key_t *ddk = &dde->dde_key;
1277         ddt_phys_t *ddp = dde->dde_phys;
1278         blkptr_t bp;
1279         zbookmark_t zb = { 0 };
1280
1281         if (scn->scn_phys.scn_state != DSS_SCANNING)
1282                 return;
1283
1284         for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
1285                 if (ddp->ddp_phys_birth == 0 ||
1286                     ddp->ddp_phys_birth > scn->scn_phys.scn_cur_max_txg)
1287                         continue;
1288                 ddt_bp_create(checksum, ddk, ddp, &bp);
1289
1290                 scn->scn_visited_this_txg++;
1291                 scan_funcs[scn->scn_phys.scn_func](scn->scn_dp, &bp, &zb);
1292         }
1293 }
1294
1295 static void
1296 dsl_scan_visit(dsl_scan_t *scn, dmu_tx_t *tx)
1297 {
1298         dsl_pool_t *dp = scn->scn_dp;
1299         zap_cursor_t zc;
1300         zap_attribute_t za;
1301
1302         if (scn->scn_phys.scn_ddt_bookmark.ddb_class <=
1303             scn->scn_phys.scn_ddt_class_max) {
1304                 scn->scn_phys.scn_cur_min_txg = scn->scn_phys.scn_min_txg;
1305                 scn->scn_phys.scn_cur_max_txg = scn->scn_phys.scn_max_txg;
1306                 dsl_scan_ddt(scn, tx);
1307                 if (scn->scn_pausing)
1308                         return;
1309         }
1310
1311         if (scn->scn_phys.scn_bookmark.zb_objset == DMU_META_OBJSET) {
1312                 /* First do the MOS & ORIGIN */
1313
1314                 scn->scn_phys.scn_cur_min_txg = scn->scn_phys.scn_min_txg;
1315                 scn->scn_phys.scn_cur_max_txg = scn->scn_phys.scn_max_txg;
1316                 dsl_scan_visit_rootbp(scn, NULL,
1317                     &dp->dp_meta_rootbp, tx);
1318                 spa_set_rootblkptr(dp->dp_spa, &dp->dp_meta_rootbp);
1319                 if (scn->scn_pausing)
1320                         return;
1321
1322                 if (spa_version(dp->dp_spa) < SPA_VERSION_DSL_SCRUB) {
1323                         VERIFY(0 == dmu_objset_find_spa(dp->dp_spa,
1324                             NULL, enqueue_cb, tx, DS_FIND_CHILDREN));
1325                 } else {
1326                         dsl_scan_visitds(scn,
1327                             dp->dp_origin_snap->ds_object, tx);
1328                 }
1329                 ASSERT(!scn->scn_pausing);
1330         } else if (scn->scn_phys.scn_bookmark.zb_objset !=
1331             ZB_DESTROYED_OBJSET) {
1332                 /*
1333                  * If we were paused, continue from here.  Note if the
1334                  * ds we were paused on was deleted, the zb_objset may
1335                  * be -1, so we will skip this and find a new objset
1336                  * below.
1337                  */
1338                 dsl_scan_visitds(scn, scn->scn_phys.scn_bookmark.zb_objset, tx);
1339                 if (scn->scn_pausing)
1340                         return;
1341         }
1342
1343         /*
1344          * In case we were paused right at the end of the ds, zero the
1345          * bookmark so we don't think that we're still trying to resume.
1346          */
1347         bzero(&scn->scn_phys.scn_bookmark, sizeof (zbookmark_t));
1348
1349         /* keep pulling things out of the zap-object-as-queue */
1350         while (zap_cursor_init(&zc, dp->dp_meta_objset,
1351             scn->scn_phys.scn_queue_obj),
1352             zap_cursor_retrieve(&zc, &za) == 0) {
1353                 dsl_dataset_t *ds;
1354                 uint64_t dsobj;
1355
1356                 dsobj = strtonum(za.za_name, NULL);
1357                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
1358                     scn->scn_phys.scn_queue_obj, dsobj, tx));
1359
1360                 /* Set up min/max txg */
1361                 VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
1362                 if (za.za_first_integer != 0) {
1363                         scn->scn_phys.scn_cur_min_txg =
1364                             MAX(scn->scn_phys.scn_min_txg,
1365                             za.za_first_integer);
1366                 } else {
1367                         scn->scn_phys.scn_cur_min_txg =
1368                             MAX(scn->scn_phys.scn_min_txg,
1369                             ds->ds_phys->ds_prev_snap_txg);
1370                 }
1371                 scn->scn_phys.scn_cur_max_txg = dsl_scan_ds_maxtxg(ds);
1372                 dsl_dataset_rele(ds, FTAG);
1373
1374                 dsl_scan_visitds(scn, dsobj, tx);
1375                 zap_cursor_fini(&zc);
1376                 if (scn->scn_pausing)
1377                         return;
1378         }
1379         zap_cursor_fini(&zc);
1380 }
1381
1382 static int
1383 dsl_scan_free_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
1384 {
1385         dsl_scan_t *scn = arg;
1386         uint64_t elapsed_nanosecs;
1387
1388         elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
1389
1390         if (elapsed_nanosecs / NANOSEC > zfs_txg_timeout ||
1391             (elapsed_nanosecs / MICROSEC > zfs_free_min_time_ms &&
1392             txg_sync_waiting(scn->scn_dp)) ||
1393             spa_shutting_down(scn->scn_dp->dp_spa))
1394                 return (ERESTART);
1395
1396         zio_nowait(zio_free_sync(scn->scn_zio_root, scn->scn_dp->dp_spa,
1397             dmu_tx_get_txg(tx), bp, 0));
1398         dsl_dir_diduse_space(tx->tx_pool->dp_free_dir, DD_USED_HEAD,
1399             -bp_get_dsize_sync(scn->scn_dp->dp_spa, bp),
1400             -BP_GET_PSIZE(bp), -BP_GET_UCSIZE(bp), tx);
1401         scn->scn_visited_this_txg++;
1402         return (0);
1403 }
1404
1405 boolean_t
1406 dsl_scan_active(dsl_scan_t *scn)
1407 {
1408         spa_t *spa = scn->scn_dp->dp_spa;
1409         uint64_t used = 0, comp, uncomp;
1410
1411         if (spa->spa_load_state != SPA_LOAD_NONE)
1412                 return (B_FALSE);
1413         if (spa_shutting_down(spa))
1414                 return (B_FALSE);
1415
1416         if (scn->scn_phys.scn_state == DSS_SCANNING)
1417                 return (B_TRUE);
1418
1419         if (spa_version(scn->scn_dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
1420                 (void) bpobj_space(&scn->scn_dp->dp_free_bpobj,
1421                     &used, &comp, &uncomp);
1422         }
1423         return (used != 0);
1424 }
1425
1426 void
1427 dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t *tx)
1428 {
1429         dsl_scan_t *scn = dp->dp_scan;
1430         spa_t *spa = dp->dp_spa;
1431         int err;
1432
1433         /*
1434          * Check for scn_restart_txg before checking spa_load_state, so
1435          * that we can restart an old-style scan while the pool is being
1436          * imported (see dsl_scan_init).
1437          */
1438         if (scn->scn_restart_txg != 0 &&
1439             scn->scn_restart_txg <= tx->tx_txg) {
1440                 pool_scan_func_t func = POOL_SCAN_SCRUB;
1441                 dsl_scan_done(scn, B_FALSE, tx);
1442                 if (vdev_resilver_needed(spa->spa_root_vdev, NULL, NULL))
1443                         func = POOL_SCAN_RESILVER;
1444                 zfs_dbgmsg("restarting scan func=%u txg=%llu",
1445                     func, tx->tx_txg);
1446                 dsl_scan_setup_sync(scn, &func, tx);
1447         }
1448
1449
1450         if (!dsl_scan_active(scn) ||
1451             spa_sync_pass(dp->dp_spa) > 1)
1452                 return;
1453
1454         scn->scn_visited_this_txg = 0;
1455         scn->scn_pausing = B_FALSE;
1456         scn->scn_sync_start_time = gethrtime();
1457         spa->spa_scrub_active = B_TRUE;
1458
1459         /*
1460          * First process the free list.  If we pause the free, don't do
1461          * any scanning.  This ensures that there is no free list when
1462          * we are scanning, so the scan code doesn't have to worry about
1463          * traversing it.
1464          */
1465         if (spa_version(dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
1466                 scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
1467                     NULL, ZIO_FLAG_MUSTSUCCEED);
1468                 err = bpobj_iterate(&dp->dp_free_bpobj,
1469                     dsl_scan_free_cb, scn, tx);
1470                 VERIFY3U(0, ==, zio_wait(scn->scn_zio_root));
1471                 if (scn->scn_visited_this_txg) {
1472                         zfs_dbgmsg("freed %llu blocks in %llums from "
1473                             "free_bpobj txg %llu",
1474                             (longlong_t)scn->scn_visited_this_txg,
1475                             (longlong_t)
1476                             (gethrtime() - scn->scn_sync_start_time) / MICROSEC,
1477                             (longlong_t)tx->tx_txg);
1478                         scn->scn_visited_this_txg = 0;
1479                         /*
1480                          * Re-sync the ddt so that we can further modify
1481                          * it when doing bprewrite.
1482                          */
1483                         ddt_sync(spa, tx->tx_txg);
1484                 }
1485                 if (err == ERESTART)
1486                         return;
1487         }
1488
1489         if (scn->scn_phys.scn_state != DSS_SCANNING)
1490                 return;
1491
1492
1493         if (scn->scn_phys.scn_ddt_bookmark.ddb_class <=
1494             scn->scn_phys.scn_ddt_class_max) {
1495                 zfs_dbgmsg("doing scan sync txg %llu; "
1496                     "ddt bm=%llu/%llu/%llu/%llx",
1497                     (longlong_t)tx->tx_txg,
1498                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_class,
1499                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_type,
1500                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_checksum,
1501                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_cursor);
1502                 ASSERT(scn->scn_phys.scn_bookmark.zb_objset == 0);
1503                 ASSERT(scn->scn_phys.scn_bookmark.zb_object == 0);
1504                 ASSERT(scn->scn_phys.scn_bookmark.zb_level == 0);
1505                 ASSERT(scn->scn_phys.scn_bookmark.zb_blkid == 0);
1506         } else {
1507                 zfs_dbgmsg("doing scan sync txg %llu; bm=%llu/%llu/%llu/%llu",
1508                     (longlong_t)tx->tx_txg,
1509                     (longlong_t)scn->scn_phys.scn_bookmark.zb_objset,
1510                     (longlong_t)scn->scn_phys.scn_bookmark.zb_object,
1511                     (longlong_t)scn->scn_phys.scn_bookmark.zb_level,
1512                     (longlong_t)scn->scn_phys.scn_bookmark.zb_blkid);
1513         }
1514
1515         scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
1516             NULL, ZIO_FLAG_CANFAIL);
1517         dsl_scan_visit(scn, tx);
1518         (void) zio_wait(scn->scn_zio_root);
1519         scn->scn_zio_root = NULL;
1520
1521         zfs_dbgmsg("visited %llu blocks in %llums",
1522             (longlong_t)scn->scn_visited_this_txg,
1523             (longlong_t)(gethrtime() - scn->scn_sync_start_time) / MICROSEC);
1524
1525         if (!scn->scn_pausing) {
1526                 /* finished with scan. */
1527                 zfs_dbgmsg("finished scan txg %llu", (longlong_t)tx->tx_txg);
1528                 dsl_scan_done(scn, B_TRUE, tx);
1529         }
1530
1531         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
1532                 mutex_enter(&spa->spa_scrub_lock);
1533                 while (spa->spa_scrub_inflight > 0) {
1534                         cv_wait(&spa->spa_scrub_io_cv,
1535                             &spa->spa_scrub_lock);
1536                 }
1537                 mutex_exit(&spa->spa_scrub_lock);
1538         }
1539
1540         dsl_scan_sync_state(scn, tx);
1541 }
1542
1543 /*
1544  * This will start a new scan, or restart an existing one.
1545  */
1546 void
1547 dsl_resilver_restart(dsl_pool_t *dp, uint64_t txg)
1548 {
1549         if (txg == 0) {
1550                 dmu_tx_t *tx;
1551                 tx = dmu_tx_create_dd(dp->dp_mos_dir);
1552                 VERIFY(0 == dmu_tx_assign(tx, TXG_WAIT));
1553
1554                 txg = dmu_tx_get_txg(tx);
1555                 dp->dp_scan->scn_restart_txg = txg;
1556                 dmu_tx_commit(tx);
1557         } else {
1558                 dp->dp_scan->scn_restart_txg = txg;
1559         }
1560         zfs_dbgmsg("restarting resilver txg=%llu", txg);
1561 }
1562
1563 boolean_t
1564 dsl_scan_resilvering(dsl_pool_t *dp)
1565 {
1566         return (dp->dp_scan->scn_phys.scn_state == DSS_SCANNING &&
1567             dp->dp_scan->scn_phys.scn_func == POOL_SCAN_RESILVER);
1568 }
1569
1570 /*
1571  * scrub consumers
1572  */
1573
1574 static void
1575 count_block(zfs_all_blkstats_t *zab, const blkptr_t *bp)
1576 {
1577         int i;
1578
1579         /*
1580          * If we resume after a reboot, zab will be NULL; don't record
1581          * incomplete stats in that case.
1582          */
1583         if (zab == NULL)
1584                 return;
1585
1586         for (i = 0; i < 4; i++) {
1587                 int l = (i < 2) ? BP_GET_LEVEL(bp) : DN_MAX_LEVELS;
1588                 int t = (i & 1) ? BP_GET_TYPE(bp) : DMU_OT_TOTAL;
1589                 zfs_blkstat_t *zb = &zab->zab_type[l][t];
1590                 int equal;
1591
1592                 zb->zb_count++;
1593                 zb->zb_asize += BP_GET_ASIZE(bp);
1594                 zb->zb_lsize += BP_GET_LSIZE(bp);
1595                 zb->zb_psize += BP_GET_PSIZE(bp);
1596                 zb->zb_gangs += BP_COUNT_GANG(bp);
1597
1598                 switch (BP_GET_NDVAS(bp)) {
1599                 case 2:
1600                         if (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1601                             DVA_GET_VDEV(&bp->blk_dva[1]))
1602                                 zb->zb_ditto_2_of_2_samevdev++;
1603                         break;
1604                 case 3:
1605                         equal = (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1606                             DVA_GET_VDEV(&bp->blk_dva[1])) +
1607                             (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1608                             DVA_GET_VDEV(&bp->blk_dva[2])) +
1609                             (DVA_GET_VDEV(&bp->blk_dva[1]) ==
1610                             DVA_GET_VDEV(&bp->blk_dva[2]));
1611                         if (equal == 1)
1612                                 zb->zb_ditto_2_of_3_samevdev++;
1613                         else if (equal == 3)
1614                                 zb->zb_ditto_3_of_3_samevdev++;
1615                         break;
1616                 }
1617         }
1618 }
1619
1620 static void
1621 dsl_scan_scrub_done(zio_t *zio)
1622 {
1623         spa_t *spa = zio->io_spa;
1624
1625         zio_data_buf_free(zio->io_data, zio->io_size);
1626
1627         mutex_enter(&spa->spa_scrub_lock);
1628         spa->spa_scrub_inflight--;
1629         cv_broadcast(&spa->spa_scrub_io_cv);
1630
1631         if (zio->io_error && (zio->io_error != ECKSUM ||
1632             !(zio->io_flags & ZIO_FLAG_SPECULATIVE))) {
1633                 spa->spa_dsl_pool->dp_scan->scn_phys.scn_errors++;
1634         }
1635         mutex_exit(&spa->spa_scrub_lock);
1636 }
1637
1638 static int
1639 dsl_scan_scrub_cb(dsl_pool_t *dp,
1640     const blkptr_t *bp, const zbookmark_t *zb)
1641 {
1642         dsl_scan_t *scn = dp->dp_scan;
1643         size_t size = BP_GET_PSIZE(bp);
1644         spa_t *spa = dp->dp_spa;
1645         uint64_t phys_birth = BP_PHYSICAL_BIRTH(bp);
1646         boolean_t needs_io;
1647         int zio_flags = ZIO_FLAG_SCRUB_THREAD | ZIO_FLAG_RAW | ZIO_FLAG_CANFAIL;
1648         int zio_priority;
1649
1650         if (phys_birth <= scn->scn_phys.scn_min_txg ||
1651             phys_birth >= scn->scn_phys.scn_max_txg)
1652                 return (0);
1653
1654         count_block(dp->dp_blkstats, bp);
1655
1656         ASSERT(DSL_SCAN_IS_SCRUB_RESILVER(scn));
1657         if (scn->scn_phys.scn_func == POOL_SCAN_SCRUB) {
1658                 zio_flags |= ZIO_FLAG_SCRUB;
1659                 zio_priority = ZIO_PRIORITY_SCRUB;
1660                 needs_io = B_TRUE;
1661         } else if (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) {
1662                 zio_flags |= ZIO_FLAG_RESILVER;
1663                 zio_priority = ZIO_PRIORITY_RESILVER;
1664                 needs_io = B_FALSE;
1665         }
1666
1667         /* If it's an intent log block, failure is expected. */
1668         if (zb->zb_level == ZB_ZIL_LEVEL)
1669                 zio_flags |= ZIO_FLAG_SPECULATIVE;
1670
1671         for (int d = 0; d < BP_GET_NDVAS(bp); d++) {
1672                 vdev_t *vd = vdev_lookup_top(spa,
1673                     DVA_GET_VDEV(&bp->blk_dva[d]));
1674
1675                 /*
1676                  * Keep track of how much data we've examined so that
1677                  * zpool(1M) status can make useful progress reports.
1678                  */
1679                 scn->scn_phys.scn_examined += DVA_GET_ASIZE(&bp->blk_dva[d]);
1680                 spa->spa_scan_pass_exam += DVA_GET_ASIZE(&bp->blk_dva[d]);
1681
1682                 /* if it's a resilver, this may not be in the target range */
1683                 if (!needs_io) {
1684                         if (DVA_GET_GANG(&bp->blk_dva[d])) {
1685                                 /*
1686                                  * Gang members may be spread across multiple
1687                                  * vdevs, so the best estimate we have is the
1688                                  * scrub range, which has already been checked.
1689                                  * XXX -- it would be better to change our
1690                                  * allocation policy to ensure that all
1691                                  * gang members reside on the same vdev.
1692                                  */
1693                                 needs_io = B_TRUE;
1694                         } else {
1695                                 needs_io = vdev_dtl_contains(vd, DTL_PARTIAL,
1696                                     phys_birth, 1);
1697                         }
1698                 }
1699         }
1700
1701         if (needs_io && !zfs_no_scrub_io) {
1702                 void *data = zio_data_buf_alloc(size);
1703
1704                 mutex_enter(&spa->spa_scrub_lock);
1705                 while (spa->spa_scrub_inflight >= spa->spa_scrub_maxinflight)
1706                         cv_wait(&spa->spa_scrub_io_cv, &spa->spa_scrub_lock);
1707                 spa->spa_scrub_inflight++;
1708                 mutex_exit(&spa->spa_scrub_lock);
1709
1710                 zio_nowait(zio_read(NULL, spa, bp, data, size,
1711                     dsl_scan_scrub_done, NULL, zio_priority,
1712                     zio_flags, zb));
1713         }
1714
1715         /* do not relocate this block */
1716         return (0);
1717 }
1718
1719 int
1720 dsl_scan(dsl_pool_t *dp, pool_scan_func_t func)
1721 {
1722         spa_t *spa = dp->dp_spa;
1723
1724         /*
1725          * Purge all vdev caches and probe all devices.  We do this here
1726          * rather than in sync context because this requires a writer lock
1727          * on the spa_config lock, which we can't do from sync context.  The
1728          * spa_scrub_reopen flag indicates that vdev_open() should not
1729          * attempt to start another scrub.
1730          */
1731         spa_vdev_state_enter(spa, SCL_NONE);
1732         spa->spa_scrub_reopen = B_TRUE;
1733         vdev_reopen(spa->spa_root_vdev);
1734         spa->spa_scrub_reopen = B_FALSE;
1735         (void) spa_vdev_state_exit(spa, NULL, 0);
1736
1737         return (dsl_sync_task_do(dp, dsl_scan_setup_check,
1738             dsl_scan_setup_sync, dp->dp_scan, &func, 0));
1739 }