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  * Copyright (c) 2012 by Delphix. All rights reserved.
  24  */
  25
  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>
  35 #include <sys/arc.h>
  36 #include <sys/zap.h>
  37 #include <sys/zio.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>
  45 #include <sys/ddt.h>
  46 #include <sys/sa.h>
  47 #include <sys/sa_impl.h>
  48 #include <sys/zfeature.h>
  49 #ifdef _KERNEL
  50 #include <sys/zfs_vfsops.h>
  51 #endif
  52
  53 typedef int (scan_cb_t)(dsl_pool_t *, const blkptr_t *, const zbookmark_t *);
  54
  55 static scan_cb_t dsl_scan_scrub_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_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 */
  63
  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 */
  71
  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)
  75
  76 /* the order has to match pool_scan_type */
  77 static scan_cb_t *scan_funcs[POOL_SCAN_FUNCS] = {
  78         NULL,
  79         dsl_scan_scrub_cb,      /* POOL_SCAN_SCRUB */
  80         dsl_scan_scrub_cb,      /* POOL_SCAN_RESILVER */
  81 };
  82
  83 int
  84 dsl_scan_init(dsl_pool_t *dp, uint64_t txg)
  85 {
  86         int err;
  87         dsl_scan_t *scn;
  88         spa_t *spa = dp->dp_spa;
  89         uint64_t f;
  90
  91         scn = dp->dp_scan = kmem_zalloc(sizeof (dsl_scan_t), KM_SLEEP);
  92         scn->scn_dp = dp;
  93
  94         err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
  95             "scrub_func", sizeof (uint64_t), 1, &f);
  96         if (err == 0) {
  97                 /*
  98                  * There was an old-style scrub in progress.  Restart a
  99                  * new-style scrub from the beginning.
 100                  */
 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);
 105
 106                 /*
 107                  * Load the queue obj from the old location so that it
 108                  * can be freed by dsl_scan_done().
 109                  */
 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);
 113         } else {
 114                 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 115                     DMU_POOL_SCAN, sizeof (uint64_t), SCAN_PHYS_NUMINTS,
 116                     &scn->scn_phys);
 117                 if (err == ENOENT)
 118                         return (0);
 119                 else if (err)
 120                         return (err);
 121
 122                 if (scn->scn_phys.scn_state == DSS_SCANNING &&
 123                     spa_prev_software_version(dp->dp_spa) < SPA_VERSION_SCAN) {
 124                         /*
 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
 129                          * the meantime.
 130                          */
 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);
 135                 }
 136         }
 137
 138         spa_scan_stat_init(spa);
 139         return (0);
 140 }
 141
 142 void
 143 dsl_scan_fini(dsl_pool_t *dp)
 144 {
 145         if (dp->dp_scan) {
 146                 kmem_free(dp->dp_scan, sizeof (dsl_scan_t));
 147                 dp->dp_scan = NULL;
 148         }
 149 }
 150
 151 /* ARGSUSED */
 152 static int
 153 dsl_scan_setup_check(void *arg1, void *arg2, dmu_tx_t *tx)
 154 {
 155         dsl_scan_t *scn = arg1;
 156
 157         if (scn->scn_phys.scn_state == DSS_SCANNING)
 158                 return (EBUSY);
 159
 160         return (0);
 161 }
 162
 163 /* ARGSUSED */
 164 static void
 165 dsl_scan_setup_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 166 {
 167         dsl_scan_t *scn = arg1;
 168         pool_scan_func_t *funcp = arg2;
 169         dmu_object_type_t ot = 0;
 170         dsl_pool_t *dp = scn->scn_dp;
 171         spa_t *spa = dp->dp_spa;
 172
 173         ASSERT(scn->scn_phys.scn_state != DSS_SCANNING);
 174         ASSERT(*funcp > POOL_SCAN_NONE && *funcp < POOL_SCAN_FUNCS);
 175         bzero(&scn->scn_phys, sizeof (scn->scn_phys));
 176         scn->scn_phys.scn_func = *funcp;
 177         scn->scn_phys.scn_state = DSS_SCANNING;
 178         scn->scn_phys.scn_min_txg = 0;
 179         scn->scn_phys.scn_max_txg = tx->tx_txg;
 180         scn->scn_phys.scn_ddt_class_max = DDT_CLASSES - 1; /* the entire DDT */
 181         scn->scn_phys.scn_start_time = gethrestime_sec();
 182         scn->scn_phys.scn_errors = 0;
 183         scn->scn_phys.scn_to_examine = spa->spa_root_vdev->vdev_stat.vs_alloc;
 184         scn->scn_restart_txg = 0;
 185         spa_scan_stat_init(spa);
 186
 187         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
 188                 scn->scn_phys.scn_ddt_class_max = zfs_scrub_ddt_class_max;
 189
 190                 /* rewrite all disk labels */
 191                 vdev_config_dirty(spa->spa_root_vdev);
 192
 193                 if (vdev_resilver_needed(spa->spa_root_vdev,
 194                     &scn->scn_phys.scn_min_txg, &scn->scn_phys.scn_max_txg)) {
 195                         spa_event_notify(spa, NULL, FM_EREPORT_ZFS_RESILVER_START);
 196                 } else {
 197                         spa_event_notify(spa, NULL, FM_EREPORT_ZFS_SCRUB_START);
 198                 }
 199
 200                 spa->spa_scrub_started = B_TRUE;
 201                 /*
 202                  * If this is an incremental scrub, limit the DDT scrub phase
 203                  * to just the auto-ditto class (for correctness); the rest
 204                  * of the scrub should go faster using top-down pruning.
 205                  */
 206                 if (scn->scn_phys.scn_min_txg > TXG_INITIAL)
 207                         scn->scn_phys.scn_ddt_class_max = DDT_CLASS_DITTO;
 208
 209         }
 210
 211         /* back to the generic stuff */
 212
 213         if (dp->dp_blkstats == NULL) {
 214                 dp->dp_blkstats = kmem_alloc(sizeof (zfs_all_blkstats_t),
 215                     KM_PUSHPAGE | KM_NODEBUG);
 216         }
 217         bzero(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
 218
 219         if (spa_version(spa) < SPA_VERSION_DSL_SCRUB)
 220                 ot = DMU_OT_ZAP_OTHER;
 221
 222         scn->scn_phys.scn_queue_obj = zap_create(dp->dp_meta_objset,
 223             ot ? ot : DMU_OT_SCAN_QUEUE, DMU_OT_NONE, 0, tx);
 224
 225         dsl_scan_sync_state(scn, tx);
 226
 227         spa_history_log_internal(LOG_POOL_SCAN, spa, tx,
 228             "func=%u mintxg=%llu maxtxg=%llu",
 229             *funcp, scn->scn_phys.scn_min_txg, scn->scn_phys.scn_max_txg);
 230 }
 231
 232 /* ARGSUSED */
 233 static void
 234 dsl_scan_done(dsl_scan_t *scn, boolean_t complete, dmu_tx_t *tx)
 235 {
 236         static const char *old_names[] = {
 237                 "scrub_bookmark",
 238                 "scrub_ddt_bookmark",
 239                 "scrub_ddt_class_max",
 240                 "scrub_queue",
 241                 "scrub_min_txg",
 242                 "scrub_max_txg",
 243                 "scrub_func",
 244                 "scrub_errors",
 245                 NULL
 246         };
 247
 248         dsl_pool_t *dp = scn->scn_dp;
 249         spa_t *spa = dp->dp_spa;
 250         int i;
 251
 252         /* Remove any remnants of an old-style scrub. */
 253         for (i = 0; old_names[i]; i++) {
 254                 (void) zap_remove(dp->dp_meta_objset,
 255                     DMU_POOL_DIRECTORY_OBJECT, old_names[i], tx);
 256         }
 257
 258         if (scn->scn_phys.scn_queue_obj != 0) {
 259                 VERIFY(0 == dmu_object_free(dp->dp_meta_objset,
 260                     scn->scn_phys.scn_queue_obj, tx));
 261                 scn->scn_phys.scn_queue_obj = 0;
 262         }
 263
 264         /*
 265          * If we were "restarted" from a stopped state, don't bother
 266          * with anything else.
 267          */
 268         if (scn->scn_phys.scn_state != DSS_SCANNING)
 269                 return;
 270
 271         if (complete)
 272                 scn->scn_phys.scn_state = DSS_FINISHED;
 273         else
 274                 scn->scn_phys.scn_state = DSS_CANCELED;
 275
 276         spa_history_log_internal(LOG_POOL_SCAN_DONE, spa, tx,
 277             "complete=%u", complete);
 278
 279         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
 280                 mutex_enter(&spa->spa_scrub_lock);
 281                 while (spa->spa_scrub_inflight > 0) {
 282                         cv_wait(&spa->spa_scrub_io_cv,
 283                             &spa->spa_scrub_lock);
 284                 }
 285                 mutex_exit(&spa->spa_scrub_lock);
 286                 spa->spa_scrub_started = B_FALSE;
 287                 spa->spa_scrub_active = B_FALSE;
 288
 289                 /*
 290                  * If the scrub/resilver completed, update all DTLs to
 291                  * reflect this.  Whether it succeeded or not, vacate
 292                  * all temporary scrub DTLs.
 293                  */
 294                 vdev_dtl_reassess(spa->spa_root_vdev, tx->tx_txg,
 295                     complete ? scn->scn_phys.scn_max_txg : 0, B_TRUE);
 296                 if (complete) {
 297                         spa_event_notify(spa, NULL, scn->scn_phys.scn_min_txg ?
 298                             FM_EREPORT_ZFS_RESILVER_FINISH :
 299                             FM_EREPORT_ZFS_SCRUB_FINISH);
 300                 }
 301                 spa_errlog_rotate(spa);
 302
 303                 /*
 304                  * We may have finished replacing a device.
 305                  * Let the async thread assess this and handle the detach.
 306                  */
 307                 spa_async_request(spa, SPA_ASYNC_RESILVER_DONE);
 308         }
 309
 310         scn->scn_phys.scn_end_time = gethrestime_sec();
 311 }
 312
 313 /* ARGSUSED */
 314 static int
 315 dsl_scan_cancel_check(void *arg1, void *arg2, dmu_tx_t *tx)
 316 {
 317         dsl_scan_t *scn = arg1;
 318
 319         if (scn->scn_phys.scn_state != DSS_SCANNING)
 320                 return (ENOENT);
 321         return (0);
 322 }
 323
 324 /* ARGSUSED */
 325 static void
 326 dsl_scan_cancel_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 327 {
 328         dsl_scan_t *scn = arg1;
 329
 330         dsl_scan_done(scn, B_FALSE, tx);
 331         dsl_scan_sync_state(scn, tx);
 332 }
 333
 334 int
 335 dsl_scan_cancel(dsl_pool_t *dp)
 336 {
 337         boolean_t complete = B_FALSE;
 338         int err;
 339
 340         err = dsl_sync_task_do(dp, dsl_scan_cancel_check,
 341             dsl_scan_cancel_sync, dp->dp_scan, &complete, 3);
 342         return (err);
 343 }
 344
 345 static void dsl_scan_visitbp(blkptr_t *bp,
 346     const zbookmark_t *zb, dnode_phys_t *dnp, arc_buf_t *pbuf,
 347     dsl_dataset_t *ds, dsl_scan_t *scn, dmu_objset_type_t ostype,
 348     dmu_tx_t *tx);
 349 inline __attribute__((always_inline)) static void dsl_scan_visitdnode(
 350     dsl_scan_t *, dsl_dataset_t *ds, dmu_objset_type_t ostype,
 351     dnode_phys_t *dnp, arc_buf_t *buf, uint64_t object, dmu_tx_t *tx);
 352
 353 void
 354 dsl_free(dsl_pool_t *dp, uint64_t txg, const blkptr_t *bp)
 355 {
 356         zio_free(dp->dp_spa, txg, bp);
 357 }
 358
 359 void
 360 dsl_free_sync(zio_t *pio, dsl_pool_t *dp, uint64_t txg, const blkptr_t *bpp)
 361 {
 362         ASSERT(dsl_pool_sync_context(dp));
 363         zio_nowait(zio_free_sync(pio, dp->dp_spa, txg, bpp, pio->io_flags));
 364 }
 365
 366 int
 367 dsl_read(zio_t *pio, spa_t *spa, const blkptr_t *bpp, arc_buf_t *pbuf,
 368     arc_done_func_t *done, void *private, int priority, int zio_flags,
 369     uint32_t *arc_flags, const zbookmark_t *zb)
 370 {
 371         return (arc_read(pio, spa, bpp, pbuf, done, private,
 372             priority, zio_flags, arc_flags, zb));
 373 }
 374
 375 int
 376 dsl_read_nolock(zio_t *pio, spa_t *spa, const blkptr_t *bpp,
 377     arc_done_func_t *done, void *private, int priority, int zio_flags,
 378     uint32_t *arc_flags, const zbookmark_t *zb)
 379 {
 380         return (arc_read_nolock(pio, spa, bpp, done, private,
 381             priority, zio_flags, arc_flags, zb));
 382 }
 383
 384 static uint64_t
 385 dsl_scan_ds_maxtxg(dsl_dataset_t *ds)
 386 {
 387         uint64_t smt = ds->ds_dir->dd_pool->dp_scan->scn_phys.scn_max_txg;
 388         if (dsl_dataset_is_snapshot(ds))
 389                 return (MIN(smt, ds->ds_phys->ds_creation_txg));
 390         return (smt);
 391 }
 392
 393 static void
 394 dsl_scan_sync_state(dsl_scan_t *scn, dmu_tx_t *tx)
 395 {
 396         VERIFY(0 == zap_update(scn->scn_dp->dp_meta_objset,
 397             DMU_POOL_DIRECTORY_OBJECT,
 398             DMU_POOL_SCAN, sizeof (uint64_t), SCAN_PHYS_NUMINTS,
 399             &scn->scn_phys, tx));
 400 }
 401
 402 static boolean_t
 403 dsl_scan_check_pause(dsl_scan_t *scn, const zbookmark_t *zb)
 404 {
 405         uint64_t elapsed_nanosecs;
 406         int mintime;
 407
 408         /* we never skip user/group accounting objects */
 409         if (zb && (int64_t)zb->zb_object < 0)
 410                 return (B_FALSE);
 411
 412         if (scn->scn_pausing)
 413                 return (B_TRUE); /* we're already pausing */
 414
 415         if (!ZB_IS_ZERO(&scn->scn_phys.scn_bookmark))
 416                 return (B_FALSE); /* we're resuming */
 417
 418         /* We only know how to resume from level-0 blocks. */
 419         if (zb && zb->zb_level != 0)
 420                 return (B_FALSE);
 421
 422         mintime = (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) ?
 423             zfs_resilver_min_time_ms : zfs_scan_min_time_ms;
 424         elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
 425         if (elapsed_nanosecs / NANOSEC > zfs_txg_timeout ||
 426             (elapsed_nanosecs / MICROSEC > mintime &&
 427             txg_sync_waiting(scn->scn_dp)) ||
 428             spa_shutting_down(scn->scn_dp->dp_spa)) {
 429                 if (zb) {
 430                         dprintf("pausing at bookmark %llx/%llx/%llx/%llx\n",
 431                             (longlong_t)zb->zb_objset,
 432                             (longlong_t)zb->zb_object,
 433                             (longlong_t)zb->zb_level,
 434                             (longlong_t)zb->zb_blkid);
 435                         scn->scn_phys.scn_bookmark = *zb;
 436                 }
 437                 dprintf("pausing at DDT bookmark %llx/%llx/%llx/%llx\n",
 438                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_class,
 439                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_type,
 440                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_checksum,
 441                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_cursor);
 442                 scn->scn_pausing = B_TRUE;
 443                 return (B_TRUE);
 444         }
 445         return (B_FALSE);
 446 }
 447
 448 typedef struct zil_scan_arg {
 449         dsl_pool_t      *zsa_dp;
 450         zil_header_t    *zsa_zh;
 451 } zil_scan_arg_t;
 452
 453 /* ARGSUSED */
 454 static int
 455 dsl_scan_zil_block(zilog_t *zilog, blkptr_t *bp, void *arg, uint64_t claim_txg)
 456 {
 457         zil_scan_arg_t *zsa = arg;
 458         dsl_pool_t *dp = zsa->zsa_dp;
 459         dsl_scan_t *scn = dp->dp_scan;
 460         zil_header_t *zh = zsa->zsa_zh;
 461         zbookmark_t zb;
 462
 463         if (bp->blk_birth <= scn->scn_phys.scn_cur_min_txg)
 464                 return (0);
 465
 466         /*
 467          * One block ("stubby") can be allocated a long time ago; we
 468          * want to visit that one because it has been allocated
 469          * (on-disk) even if it hasn't been claimed (even though for
 470          * scrub there's nothing to do to it).
 471          */
 472         if (claim_txg == 0 && bp->blk_birth >= spa_first_txg(dp->dp_spa))
 473                 return (0);
 474
 475         SET_BOOKMARK(&zb, zh->zh_log.blk_cksum.zc_word[ZIL_ZC_OBJSET],
 476             ZB_ZIL_OBJECT, ZB_ZIL_LEVEL, bp->blk_cksum.zc_word[ZIL_ZC_SEQ]);
 477
 478         VERIFY(0 == scan_funcs[scn->scn_phys.scn_func](dp, bp, &zb));
 479         return (0);
 480 }
 481
 482 /* ARGSUSED */
 483 static int
 484 dsl_scan_zil_record(zilog_t *zilog, lr_t *lrc, void *arg, uint64_t claim_txg)
 485 {
 486         if (lrc->lrc_txtype == TX_WRITE) {
 487                 zil_scan_arg_t *zsa = arg;
 488                 dsl_pool_t *dp = zsa->zsa_dp;
 489                 dsl_scan_t *scn = dp->dp_scan;
 490                 zil_header_t *zh = zsa->zsa_zh;
 491                 lr_write_t *lr = (lr_write_t *)lrc;
 492                 blkptr_t *bp = &lr->lr_blkptr;
 493                 zbookmark_t zb;
 494
 495                 if (bp->blk_birth <= scn->scn_phys.scn_cur_min_txg)
 496                         return (0);
 497
 498                 /*
 499                  * birth can be < claim_txg if this record's txg is
 500                  * already txg sync'ed (but this log block contains
 501                  * other records that are not synced)
 502                  */
 503                 if (claim_txg == 0 || bp->blk_birth < claim_txg)
 504                         return (0);
 505
 506                 SET_BOOKMARK(&zb, zh->zh_log.blk_cksum.zc_word[ZIL_ZC_OBJSET],
 507                     lr->lr_foid, ZB_ZIL_LEVEL,
 508                     lr->lr_offset / BP_GET_LSIZE(bp));
 509
 510                 VERIFY(0 == scan_funcs[scn->scn_phys.scn_func](dp, bp, &zb));
 511         }
 512         return (0);
 513 }
 514
 515 static void
 516 dsl_scan_zil(dsl_pool_t *dp, zil_header_t *zh)
 517 {
 518         uint64_t claim_txg = zh->zh_claim_txg;
 519         zil_scan_arg_t zsa = { dp, zh };
 520         zilog_t *zilog;
 521
 522         /*
 523          * We only want to visit blocks that have been claimed but not yet
 524          * replayed (or, in read-only mode, blocks that *would* be claimed).
 525          */
 526         if (claim_txg == 0 && spa_writeable(dp->dp_spa))
 527                 return;
 528
 529         zilog = zil_alloc(dp->dp_meta_objset, zh);
 530
 531         (void) zil_parse(zilog, dsl_scan_zil_block, dsl_scan_zil_record, &zsa,
 532             claim_txg);
 533
 534         zil_free(zilog);
 535 }
 536
 537 /* ARGSUSED */
 538 static void
 539 dsl_scan_prefetch(dsl_scan_t *scn, arc_buf_t *buf, blkptr_t *bp,
 540     uint64_t objset, uint64_t object, uint64_t blkid)
 541 {
 542         zbookmark_t czb;
 543         uint32_t flags = ARC_NOWAIT | ARC_PREFETCH;
 544
 545         if (zfs_no_scrub_prefetch)
 546                 return;
 547
 548         if (BP_IS_HOLE(bp) || bp->blk_birth <= scn->scn_phys.scn_min_txg ||
 549             (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_DNODE))
 550                 return;
 551
 552         SET_BOOKMARK(&czb, objset, object, BP_GET_LEVEL(bp), blkid);
 553
 554         /*
 555          * XXX need to make sure all of these arc_read() prefetches are
 556          * done before setting xlateall (similar to dsl_read())
 557          */
 558         (void) arc_read(scn->scn_zio_root, scn->scn_dp->dp_spa, bp,
 559             buf, NULL, NULL, ZIO_PRIORITY_ASYNC_READ,
 560             ZIO_FLAG_CANFAIL | ZIO_FLAG_SCAN_THREAD, &flags, &czb);
 561 }
 562
 563 static boolean_t
 564 dsl_scan_check_resume(dsl_scan_t *scn, const dnode_phys_t *dnp,
 565     const zbookmark_t *zb)
 566 {
 567         /*
 568          * We never skip over user/group accounting objects (obj<0)
 569          */
 570         if (!ZB_IS_ZERO(&scn->scn_phys.scn_bookmark) &&
 571             (int64_t)zb->zb_object >= 0) {
 572                 /*
 573                  * If we already visited this bp & everything below (in
 574                  * a prior txg sync), don't bother doing it again.
 575                  */
 576                 if (zbookmark_is_before(dnp, zb, &scn->scn_phys.scn_bookmark))
 577                         return (B_TRUE);
 578
 579                 /*
 580                  * If we found the block we're trying to resume from, or
 581                  * we went past it to a different object, zero it out to
 582                  * indicate that it's OK to start checking for pausing
 583                  * again.
 584                  */
 585                 if (bcmp(zb, &scn->scn_phys.scn_bookmark, sizeof (*zb)) == 0 ||
 586                     zb->zb_object > scn->scn_phys.scn_bookmark.zb_object) {
 587                         dprintf("resuming at %llx/%llx/%llx/%llx\n",
 588                             (longlong_t)zb->zb_objset,
 589                             (longlong_t)zb->zb_object,
 590                             (longlong_t)zb->zb_level,
 591                             (longlong_t)zb->zb_blkid);
 592                         bzero(&scn->scn_phys.scn_bookmark, sizeof (*zb));
 593                 }
 594         }
 595         return (B_FALSE);
 596 }
 597
 598 /*
 599  * Return nonzero on i/o error.
 600  * Return new buf to write out in *bufp.
 601  */
 602 inline __attribute__((always_inline)) static int
 603 dsl_scan_recurse(dsl_scan_t *scn, dsl_dataset_t *ds, dmu_objset_type_t ostype,
 604     dnode_phys_t *dnp, const blkptr_t *bp,
 605     const zbookmark_t *zb, dmu_tx_t *tx, arc_buf_t **bufp)
 606 {
 607         dsl_pool_t *dp = scn->scn_dp;
 608         int zio_flags = ZIO_FLAG_CANFAIL | ZIO_FLAG_SCAN_THREAD;
 609         int err;
 610
 611         if (BP_GET_LEVEL(bp) > 0) {
 612                 uint32_t flags = ARC_WAIT;
 613                 int i;
 614                 blkptr_t *cbp;
 615                 int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT;
 616
 617                 err = arc_read_nolock(NULL, dp->dp_spa, bp,
 618                     arc_getbuf_func, bufp,
 619                     ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
 620                 if (err) {
 621                         scn->scn_phys.scn_errors++;
 622                         return (err);
 623                 }
 624                 for (i = 0, cbp = (*bufp)->b_data; i < epb; i++, cbp++) {
 625                         dsl_scan_prefetch(scn, *bufp, cbp, zb->zb_objset,
 626                             zb->zb_object, zb->zb_blkid * epb + i);
 627                 }
 628                 for (i = 0, cbp = (*bufp)->b_data; i < epb; i++, cbp++) {
 629                         zbookmark_t czb;
 630
 631                         SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
 632                             zb->zb_level - 1,
 633                             zb->zb_blkid * epb + i);
 634                         dsl_scan_visitbp(cbp, &czb, dnp,
 635                             *bufp, ds, scn, ostype, tx);
 636                 }
 637         } else if (BP_GET_TYPE(bp) == DMU_OT_USERGROUP_USED) {
 638                 uint32_t flags = ARC_WAIT;
 639
 640                 err = arc_read_nolock(NULL, dp->dp_spa, bp,
 641                     arc_getbuf_func, bufp,
 642                     ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
 643                 if (err) {
 644                         scn->scn_phys.scn_errors++;
 645                         return (err);
 646                 }
 647         } else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) {
 648                 uint32_t flags = ARC_WAIT;
 649                 dnode_phys_t *cdnp;
 650                 int i, j;
 651                 int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT;
 652
 653                 err = arc_read_nolock(NULL, dp->dp_spa, bp,
 654                     arc_getbuf_func, bufp,
 655                     ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
 656                 if (err) {
 657                         scn->scn_phys.scn_errors++;
 658                         return (err);
 659                 }
 660                 for (i = 0, cdnp = (*bufp)->b_data; i < epb; i++, cdnp++) {
 661                         for (j = 0; j < cdnp->dn_nblkptr; j++) {
 662                                 blkptr_t *cbp = &cdnp->dn_blkptr[j];
 663                                 dsl_scan_prefetch(scn, *bufp, cbp,
 664                                     zb->zb_objset, zb->zb_blkid * epb + i, j);
 665                         }
 666                 }
 667                 for (i = 0, cdnp = (*bufp)->b_data; i < epb; i++, cdnp++) {
 668                         dsl_scan_visitdnode(scn, ds, ostype,
 669                             cdnp, *bufp, zb->zb_blkid * epb + i, tx);
 670                 }
 671
 672         } else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) {
 673                 uint32_t flags = ARC_WAIT;
 674                 objset_phys_t *osp;
 675
 676                 err = arc_read_nolock(NULL, dp->dp_spa, bp,
 677                     arc_getbuf_func, bufp,
 678                     ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
 679                 if (err) {
 680                         scn->scn_phys.scn_errors++;
 681                         return (err);
 682                 }
 683
 684                 osp = (*bufp)->b_data;
 685
 686                 dsl_scan_visitdnode(scn, ds, osp->os_type,
 687                     &osp->os_meta_dnode, *bufp, DMU_META_DNODE_OBJECT, tx);
 688
 689                 if (OBJSET_BUF_HAS_USERUSED(*bufp)) {
 690                         /*
 691                          * We also always visit user/group accounting
 692                          * objects, and never skip them, even if we are
 693                          * pausing.  This is necessary so that the space
 694                          * deltas from this txg get integrated.
 695                          */
 696                         dsl_scan_visitdnode(scn, ds, osp->os_type,
 697                             &osp->os_groupused_dnode, *bufp,
 698                             DMU_GROUPUSED_OBJECT, tx);
 699                         dsl_scan_visitdnode(scn, ds, osp->os_type,
 700                             &osp->os_userused_dnode, *bufp,
 701                             DMU_USERUSED_OBJECT, tx);
 702                 }
 703         }
 704
 705         return (0);
 706 }
 707
 708 inline __attribute__((always_inline)) static void
 709 dsl_scan_visitdnode(dsl_scan_t *scn, dsl_dataset_t *ds,
 710     dmu_objset_type_t ostype, dnode_phys_t *dnp, arc_buf_t *buf,
 711     uint64_t object, dmu_tx_t *tx)
 712 {
 713         int j;
 714
 715         for (j = 0; j < dnp->dn_nblkptr; j++) {
 716                 zbookmark_t czb;
 717
 718                 SET_BOOKMARK(&czb, ds ? ds->ds_object : 0, object,
 719                     dnp->dn_nlevels - 1, j);
 720                 dsl_scan_visitbp(&dnp->dn_blkptr[j],
 721                     &czb, dnp, buf, ds, scn, ostype, tx);
 722         }
 723
 724         if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
 725                 zbookmark_t czb;
 726                 SET_BOOKMARK(&czb, ds ? ds->ds_object : 0, object,
 727                     0, DMU_SPILL_BLKID);
 728                 dsl_scan_visitbp(&dnp->dn_spill,
 729                     &czb, dnp, buf, ds, scn, ostype, tx);
 730         }
 731 }
 732
 733 /*
 734  * The arguments are in this order because mdb can only print the
 735  * first 5; we want them to be useful.
 736  */
 737 static void
 738 dsl_scan_visitbp(blkptr_t *bp, const zbookmark_t *zb,
 739     dnode_phys_t *dnp, arc_buf_t *pbuf,
 740     dsl_dataset_t *ds, dsl_scan_t *scn, dmu_objset_type_t ostype,
 741     dmu_tx_t *tx)
 742 {
 743         dsl_pool_t *dp = scn->scn_dp;
 744         arc_buf_t *buf = NULL;
 745         blkptr_t *bp_toread;
 746
 747         bp_toread = kmem_alloc(sizeof (blkptr_t), KM_PUSHPAGE);
 748         *bp_toread = *bp;
 749
 750         /* ASSERT(pbuf == NULL || arc_released(pbuf)); */
 751
 752         if (dsl_scan_check_pause(scn, zb))
 753                 goto out;
 754
 755         if (dsl_scan_check_resume(scn, dnp, zb))
 756                 goto out;
 757
 758         if (bp->blk_birth == 0)
 759                 goto out;
 760
 761         scn->scn_visited_this_txg++;
 762
 763         /*
 764          * This debugging is commented out to conserve stack space.  This
 765          * function is called recursively and the debugging addes several
 766          * bytes to the stack for each call.  It can be commented back in
 767          * if required to debug an issue in dsl_scan_visitbp().
 768          *
 769          * dprintf_bp(bp,
 770          *    "visiting ds=%p/%llu zb=%llx/%llx/%llx/%llx buf=%p bp=%p",
 771          *    ds, ds ? ds->ds_object : 0,
 772          *    zb->zb_objset, zb->zb_object, zb->zb_level, zb->zb_blkid,
 773          *    pbuf, bp);
 774          */
 775
 776         if (bp->blk_birth <= scn->scn_phys.scn_cur_min_txg)
 777                 goto out;
 778
 779         if (dsl_scan_recurse(scn, ds, ostype, dnp, bp_toread, zb, tx,
 780             &buf) != 0)
 781                 goto out;
 782
 783         /*
 784          * If dsl_scan_ddt() has aready visited this block, it will have
 785          * already done any translations or scrubbing, so don't call the
 786          * callback again.
 787          */
 788         if (ddt_class_contains(dp->dp_spa,
 789             scn->scn_phys.scn_ddt_class_max, bp)) {
 790                 ASSERT(buf == NULL);
 791                 goto out;
 792         }
 793
 794         /*
 795          * If this block is from the future (after cur_max_txg), then we
 796          * are doing this on behalf of a deleted snapshot, and we will
 797          * revisit the future block on the next pass of this dataset.
 798          * Don't scan it now unless we need to because something
 799          * under it was modified.
 800          */
 801         if (bp->blk_birth <= scn->scn_phys.scn_cur_max_txg) {
 802                 scan_funcs[scn->scn_phys.scn_func](dp, bp, zb);
 803         }
 804         if (buf)
 805                 (void) arc_buf_remove_ref(buf, &buf);
 806 out:
 807         kmem_free(bp_toread, sizeof(blkptr_t));
 808 }
 809
 810 static void
 811 dsl_scan_visit_rootbp(dsl_scan_t *scn, dsl_dataset_t *ds, blkptr_t *bp,
 812     dmu_tx_t *tx)
 813 {
 814         zbookmark_t zb;
 815
 816         SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
 817             ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
 818         dsl_scan_visitbp(bp, &zb, NULL, NULL,
 819             ds, scn, DMU_OST_NONE, tx);
 820
 821         dprintf_ds(ds, "finished scan%s", "");
 822 }
 823
 824 void
 825 dsl_scan_ds_destroyed(dsl_dataset_t *ds, dmu_tx_t *tx)
 826 {
 827         dsl_pool_t *dp = ds->ds_dir->dd_pool;
 828         dsl_scan_t *scn = dp->dp_scan;
 829         uint64_t mintxg;
 830
 831         if (scn->scn_phys.scn_state != DSS_SCANNING)
 832                 return;
 833
 834         if (scn->scn_phys.scn_bookmark.zb_objset == ds->ds_object) {
 835                 if (dsl_dataset_is_snapshot(ds)) {
 836                         /* Note, scn_cur_{min,max}_txg stays the same. */
 837                         scn->scn_phys.scn_bookmark.zb_objset =
 838                             ds->ds_phys->ds_next_snap_obj;
 839                         zfs_dbgmsg("destroying ds %llu; currently traversing; "
 840                             "reset zb_objset to %llu",
 841                             (u_longlong_t)ds->ds_object,
 842                             (u_longlong_t)ds->ds_phys->ds_next_snap_obj);
 843                         scn->scn_phys.scn_flags |= DSF_VISIT_DS_AGAIN;
 844                 } else {
 845                         SET_BOOKMARK(&scn->scn_phys.scn_bookmark,
 846                             ZB_DESTROYED_OBJSET, 0, 0, 0);
 847                         zfs_dbgmsg("destroying ds %llu; currently traversing; "
 848                             "reset bookmark to -1,0,0,0",
 849                             (u_longlong_t)ds->ds_object);
 850                 }
 851         } else if (zap_lookup_int_key(dp->dp_meta_objset,
 852             scn->scn_phys.scn_queue_obj, ds->ds_object, &mintxg) == 0) {
 853                 ASSERT3U(ds->ds_phys->ds_num_children, <=, 1);
 854                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 855                     scn->scn_phys.scn_queue_obj, ds->ds_object, tx));
 856                 if (dsl_dataset_is_snapshot(ds)) {
 857                         /*
 858                          * We keep the same mintxg; it could be >
 859                          * ds_creation_txg if the previous snapshot was
 860                          * deleted too.
 861                          */
 862                         VERIFY(zap_add_int_key(dp->dp_meta_objset,
 863                             scn->scn_phys.scn_queue_obj,
 864                             ds->ds_phys->ds_next_snap_obj, mintxg, tx) == 0);
 865                         zfs_dbgmsg("destroying ds %llu; in queue; "
 866                             "replacing with %llu",
 867                             (u_longlong_t)ds->ds_object,
 868                             (u_longlong_t)ds->ds_phys->ds_next_snap_obj);
 869                 } else {
 870                         zfs_dbgmsg("destroying ds %llu; in queue; removing",
 871                             (u_longlong_t)ds->ds_object);
 872                 }
 873         } else {
 874                 zfs_dbgmsg("destroying ds %llu; ignoring",
 875                     (u_longlong_t)ds->ds_object);
 876         }
 877
 878         /*
 879          * dsl_scan_sync() should be called after this, and should sync
 880          * out our changed state, but just to be safe, do it here.
 881          */
 882         dsl_scan_sync_state(scn, tx);
 883 }
 884
 885 void
 886 dsl_scan_ds_snapshotted(dsl_dataset_t *ds, dmu_tx_t *tx)
 887 {
 888         dsl_pool_t *dp = ds->ds_dir->dd_pool;
 889         dsl_scan_t *scn = dp->dp_scan;
 890         uint64_t mintxg;
 891
 892         if (scn->scn_phys.scn_state != DSS_SCANNING)
 893                 return;
 894
 895         ASSERT(ds->ds_phys->ds_prev_snap_obj != 0);
 896
 897         if (scn->scn_phys.scn_bookmark.zb_objset == ds->ds_object) {
 898                 scn->scn_phys.scn_bookmark.zb_objset =
 899                     ds->ds_phys->ds_prev_snap_obj;
 900                 zfs_dbgmsg("snapshotting ds %llu; currently traversing; "
 901                     "reset zb_objset to %llu",
 902                     (u_longlong_t)ds->ds_object,
 903                     (u_longlong_t)ds->ds_phys->ds_prev_snap_obj);
 904         } else if (zap_lookup_int_key(dp->dp_meta_objset,
 905             scn->scn_phys.scn_queue_obj, ds->ds_object, &mintxg) == 0) {
 906                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 907                     scn->scn_phys.scn_queue_obj, ds->ds_object, tx));
 908                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
 909                     scn->scn_phys.scn_queue_obj,
 910                     ds->ds_phys->ds_prev_snap_obj, mintxg, tx) == 0);
 911                 zfs_dbgmsg("snapshotting ds %llu; in queue; "
 912                     "replacing with %llu",
 913                     (u_longlong_t)ds->ds_object,
 914                     (u_longlong_t)ds->ds_phys->ds_prev_snap_obj);
 915         }
 916         dsl_scan_sync_state(scn, tx);
 917 }
 918
 919 void
 920 dsl_scan_ds_clone_swapped(dsl_dataset_t *ds1, dsl_dataset_t *ds2, dmu_tx_t *tx)
 921 {
 922         dsl_pool_t *dp = ds1->ds_dir->dd_pool;
 923         dsl_scan_t *scn = dp->dp_scan;
 924         uint64_t mintxg;
 925
 926         if (scn->scn_phys.scn_state != DSS_SCANNING)
 927                 return;
 928
 929         if (scn->scn_phys.scn_bookmark.zb_objset == ds1->ds_object) {
 930                 scn->scn_phys.scn_bookmark.zb_objset = ds2->ds_object;
 931                 zfs_dbgmsg("clone_swap ds %llu; currently traversing; "
 932                     "reset zb_objset to %llu",
 933                     (u_longlong_t)ds1->ds_object,
 934                     (u_longlong_t)ds2->ds_object);
 935         } else if (scn->scn_phys.scn_bookmark.zb_objset == ds2->ds_object) {
 936                 scn->scn_phys.scn_bookmark.zb_objset = ds1->ds_object;
 937                 zfs_dbgmsg("clone_swap ds %llu; currently traversing; "
 938                     "reset zb_objset to %llu",
 939                     (u_longlong_t)ds2->ds_object,
 940                     (u_longlong_t)ds1->ds_object);
 941         }
 942
 943         if (zap_lookup_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
 944             ds1->ds_object, &mintxg) == 0) {
 945                 int err;
 946
 947                 ASSERT3U(mintxg, ==, ds1->ds_phys->ds_prev_snap_txg);
 948                 ASSERT3U(mintxg, ==, ds2->ds_phys->ds_prev_snap_txg);
 949                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 950                     scn->scn_phys.scn_queue_obj, ds1->ds_object, tx));
 951                 err = zap_add_int_key(dp->dp_meta_objset,
 952                     scn->scn_phys.scn_queue_obj, ds2->ds_object, mintxg, tx);
 953                 VERIFY(err == 0 || err == EEXIST);
 954                 if (err == EEXIST) {
 955                         /* Both were there to begin with */
 956                         VERIFY(0 == zap_add_int_key(dp->dp_meta_objset,
 957                             scn->scn_phys.scn_queue_obj,
 958                             ds1->ds_object, mintxg, tx));
 959                 }
 960                 zfs_dbgmsg("clone_swap ds %llu; in queue; "
 961                     "replacing with %llu",
 962                     (u_longlong_t)ds1->ds_object,
 963                     (u_longlong_t)ds2->ds_object);
 964         } else if (zap_lookup_int_key(dp->dp_meta_objset,
 965             scn->scn_phys.scn_queue_obj, ds2->ds_object, &mintxg) == 0) {
 966                 ASSERT3U(mintxg, ==, ds1->ds_phys->ds_prev_snap_txg);
 967                 ASSERT3U(mintxg, ==, ds2->ds_phys->ds_prev_snap_txg);
 968                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 969                     scn->scn_phys.scn_queue_obj, ds2->ds_object, tx));
 970                 VERIFY(0 == zap_add_int_key(dp->dp_meta_objset,
 971                     scn->scn_phys.scn_queue_obj, ds1->ds_object, mintxg, tx));
 972                 zfs_dbgmsg("clone_swap ds %llu; in queue; "
 973                     "replacing with %llu",
 974                     (u_longlong_t)ds2->ds_object,
 975                     (u_longlong_t)ds1->ds_object);
 976         }
 977
 978         dsl_scan_sync_state(scn, tx);
 979 }
 980
 981 struct enqueue_clones_arg {
 982         dmu_tx_t *tx;
 983         uint64_t originobj;
 984 };
 985
 986 /* ARGSUSED */
 987 static int
 988 enqueue_clones_cb(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
 989 {
 990         struct enqueue_clones_arg *eca = arg;
 991         dsl_dataset_t *ds;
 992         int err;
 993         dsl_pool_t *dp = spa->spa_dsl_pool;
 994         dsl_scan_t *scn = dp->dp_scan;
 995
 996         err = dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds);
 997         if (err)
 998                 return (err);
 999
1000         if (ds->ds_dir->dd_phys->dd_origin_obj == eca->originobj) {
1001                 while (ds->ds_phys->ds_prev_snap_obj != eca->originobj) {
1002                         dsl_dataset_t *prev;
1003                         err = dsl_dataset_hold_obj(dp,
1004                             ds->ds_phys->ds_prev_snap_obj, FTAG, &prev);
1005
1006                         dsl_dataset_rele(ds, FTAG);
1007                         if (err)
1008                                 return (err);
1009                         ds = prev;
1010                 }
1011                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
1012                     scn->scn_phys.scn_queue_obj, ds->ds_object,
1013                     ds->ds_phys->ds_prev_snap_txg, eca->tx) == 0);
1014         }
1015         dsl_dataset_rele(ds, FTAG);
1016         return (0);
1017 }
1018
1019 static void
1020 dsl_scan_visitds(dsl_scan_t *scn, uint64_t dsobj, dmu_tx_t *tx)
1021 {
1022         dsl_pool_t *dp = scn->scn_dp;
1023         dsl_dataset_t *ds;
1024         objset_t *os;
1025         char *dsname;
1026
1027         VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
1028
1029         if (dmu_objset_from_ds(ds, &os))
1030                 goto out;
1031
1032         /*
1033          * Only the ZIL in the head (non-snapshot) is valid.  Even though
1034          * snapshots can have ZIL block pointers (which may be the same
1035          * BP as in the head), they must be ignored.  So we traverse the
1036          * ZIL here, rather than in scan_recurse(), because the regular
1037          * snapshot block-sharing rules don't apply to it.
1038          */
1039         if (DSL_SCAN_IS_SCRUB_RESILVER(scn) && !dsl_dataset_is_snapshot(ds))
1040                 dsl_scan_zil(dp, &os->os_zil_header);
1041
1042         /*
1043          * Iterate over the bps in this ds.
1044          */
1045         dmu_buf_will_dirty(ds->ds_dbuf, tx);
1046         dsl_scan_visit_rootbp(scn, ds, &ds->ds_phys->ds_bp, tx);
1047
1048         dsname = kmem_alloc(ZFS_MAXNAMELEN, KM_PUSHPAGE);
1049         dsl_dataset_name(ds, dsname);
1050         zfs_dbgmsg("scanned dataset %llu (%s) with min=%llu max=%llu; "
1051             "pausing=%u",
1052             (longlong_t)dsobj, dsname,
1053             (longlong_t)scn->scn_phys.scn_cur_min_txg,
1054             (longlong_t)scn->scn_phys.scn_cur_max_txg,
1055             (int)scn->scn_pausing);
1056         kmem_free(dsname, ZFS_MAXNAMELEN);
1057
1058         if (scn->scn_pausing)
1059                 goto out;
1060
1061         /*
1062          * We've finished this pass over this dataset.
1063          */
1064
1065         /*
1066          * If we did not completely visit this dataset, do another pass.
1067          */
1068         if (scn->scn_phys.scn_flags & DSF_VISIT_DS_AGAIN) {
1069                 zfs_dbgmsg("incomplete pass; visiting again");
1070                 scn->scn_phys.scn_flags &= ~DSF_VISIT_DS_AGAIN;
1071                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
1072                     scn->scn_phys.scn_queue_obj, ds->ds_object,
1073                     scn->scn_phys.scn_cur_max_txg, tx) == 0);
1074                 goto out;
1075         }
1076
1077         /*
1078          * Add descendent datasets to work queue.
1079          */
1080         if (ds->ds_phys->ds_next_snap_obj != 0) {
1081                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
1082                     scn->scn_phys.scn_queue_obj, ds->ds_phys->ds_next_snap_obj,
1083                     ds->ds_phys->ds_creation_txg, tx) == 0);
1084         }
1085         if (ds->ds_phys->ds_num_children > 1) {
1086                 boolean_t usenext = B_FALSE;
1087                 if (ds->ds_phys->ds_next_clones_obj != 0) {
1088                         uint64_t count;
1089                         /*
1090                          * A bug in a previous version of the code could
1091                          * cause upgrade_clones_cb() to not set
1092                          * ds_next_snap_obj when it should, leading to a
1093                          * missing entry.  Therefore we can only use the
1094                          * next_clones_obj when its count is correct.
1095                          */
1096                         int err = zap_count(dp->dp_meta_objset,
1097                             ds->ds_phys->ds_next_clones_obj, &count);
1098                         if (err == 0 &&
1099                             count == ds->ds_phys->ds_num_children - 1)
1100                                 usenext = B_TRUE;
1101                 }
1102
1103                 if (usenext) {
1104                         VERIFY(zap_join_key(dp->dp_meta_objset,
1105                             ds->ds_phys->ds_next_clones_obj,
1106                             scn->scn_phys.scn_queue_obj,
1107                             ds->ds_phys->ds_creation_txg, tx) == 0);
1108                 } else {
1109                         struct enqueue_clones_arg eca;
1110                         eca.tx = tx;
1111                         eca.originobj = ds->ds_object;
1112
1113                         (void) dmu_objset_find_spa(ds->ds_dir->dd_pool->dp_spa,
1114                             NULL, enqueue_clones_cb, &eca, DS_FIND_CHILDREN);
1115                 }
1116         }
1117
1118 out:
1119         dsl_dataset_rele(ds, FTAG);
1120 }
1121
1122 /* ARGSUSED */
1123 static int
1124 enqueue_cb(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
1125 {
1126         dmu_tx_t *tx = arg;
1127         dsl_dataset_t *ds;
1128         int err;
1129         dsl_pool_t *dp = spa->spa_dsl_pool;
1130         dsl_scan_t *scn = dp->dp_scan;
1131
1132         err = dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds);
1133         if (err)
1134                 return (err);
1135
1136         while (ds->ds_phys->ds_prev_snap_obj != 0) {
1137                 dsl_dataset_t *prev;
1138                 err = dsl_dataset_hold_obj(dp, ds->ds_phys->ds_prev_snap_obj,
1139                     FTAG, &prev);
1140                 if (err) {
1141                         dsl_dataset_rele(ds, FTAG);
1142                         return (err);
1143                 }
1144
1145                 /*
1146                  * If this is a clone, we don't need to worry about it for now.
1147                  */
1148                 if (prev->ds_phys->ds_next_snap_obj != ds->ds_object) {
1149                         dsl_dataset_rele(ds, FTAG);
1150                         dsl_dataset_rele(prev, FTAG);
1151                         return (0);
1152                 }
1153                 dsl_dataset_rele(ds, FTAG);
1154                 ds = prev;
1155         }
1156
1157         VERIFY(zap_add_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
1158             ds->ds_object, ds->ds_phys->ds_prev_snap_txg, tx) == 0);
1159         dsl_dataset_rele(ds, FTAG);
1160         return (0);
1161 }
1162
1163 /*
1164  * Scrub/dedup interaction.
1165  *
1166  * If there are N references to a deduped block, we don't want to scrub it
1167  * N times -- ideally, we should scrub it exactly once.
1168  *
1169  * We leverage the fact that the dde's replication class (enum ddt_class)
1170  * is ordered from highest replication class (DDT_CLASS_DITTO) to lowest
1171  * (DDT_CLASS_UNIQUE) so that we may walk the DDT in that order.
1172  *
1173  * To prevent excess scrubbing, the scrub begins by walking the DDT
1174  * to find all blocks with refcnt > 1, and scrubs each of these once.
1175  * Since there are two replication classes which contain blocks with
1176  * refcnt > 1, we scrub the highest replication class (DDT_CLASS_DITTO) first.
1177  * Finally the top-down scrub begins, only visiting blocks with refcnt == 1.
1178  *
1179  * There would be nothing more to say if a block's refcnt couldn't change
1180  * during a scrub, but of course it can so we must account for changes
1181  * in a block's replication class.
1182  *
1183  * Here's an example of what can occur:
1184  *
1185  * If a block has refcnt > 1 during the DDT scrub phase, but has refcnt == 1
1186  * when visited during the top-down scrub phase, it will be scrubbed twice.
1187  * This negates our scrub optimization, but is otherwise harmless.
1188  *
1189  * If a block has refcnt == 1 during the DDT scrub phase, but has refcnt > 1
1190  * on each visit during the top-down scrub phase, it will never be scrubbed.
1191  * To catch this, ddt_sync_entry() notifies the scrub code whenever a block's
1192  * reference class transitions to a higher level (i.e DDT_CLASS_UNIQUE to
1193  * DDT_CLASS_DUPLICATE); if it transitions from refcnt == 1 to refcnt > 1
1194  * while a scrub is in progress, it scrubs the block right then.
1195  */
1196 static void
1197 dsl_scan_ddt(dsl_scan_t *scn, dmu_tx_t *tx)
1198 {
1199         ddt_bookmark_t *ddb = &scn->scn_phys.scn_ddt_bookmark;
1200         ddt_entry_t dde;
1201         int error;
1202         uint64_t n = 0;
1203
1204         bzero(&dde, sizeof (ddt_entry_t));
1205
1206         while ((error = ddt_walk(scn->scn_dp->dp_spa, ddb, &dde)) == 0) {
1207                 ddt_t *ddt;
1208
1209                 if (ddb->ddb_class > scn->scn_phys.scn_ddt_class_max)
1210                         break;
1211                 dprintf("visiting ddb=%llu/%llu/%llu/%llx\n",
1212                     (longlong_t)ddb->ddb_class,
1213                     (longlong_t)ddb->ddb_type,
1214                     (longlong_t)ddb->ddb_checksum,
1215                     (longlong_t)ddb->ddb_cursor);
1216
1217                 /* There should be no pending changes to the dedup table */
1218                 ddt = scn->scn_dp->dp_spa->spa_ddt[ddb->ddb_checksum];
1219                 ASSERT(avl_first(&ddt->ddt_tree) == NULL);
1220
1221                 dsl_scan_ddt_entry(scn, ddb->ddb_checksum, &dde, tx);
1222                 n++;
1223
1224                 if (dsl_scan_check_pause(scn, NULL))
1225                         break;
1226         }
1227
1228         zfs_dbgmsg("scanned %llu ddt entries with class_max = %u; pausing=%u",
1229             (longlong_t)n, (int)scn->scn_phys.scn_ddt_class_max,
1230             (int)scn->scn_pausing);
1231
1232         ASSERT(error == 0 || error == ENOENT);
1233         ASSERT(error != ENOENT ||
1234             ddb->ddb_class > scn->scn_phys.scn_ddt_class_max);
1235 }
1236
1237 /* ARGSUSED */
1238 void
1239 dsl_scan_ddt_entry(dsl_scan_t *scn, enum zio_checksum checksum,
1240     ddt_entry_t *dde, dmu_tx_t *tx)
1241 {
1242         const ddt_key_t *ddk = &dde->dde_key;
1243         ddt_phys_t *ddp = dde->dde_phys;
1244         blkptr_t bp;
1245         zbookmark_t zb = { 0 };
1246         int p;
1247
1248         if (scn->scn_phys.scn_state != DSS_SCANNING)
1249                 return;
1250
1251         for (p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
1252                 if (ddp->ddp_phys_birth == 0 ||
1253                     ddp->ddp_phys_birth > scn->scn_phys.scn_cur_max_txg)
1254                         continue;
1255                 ddt_bp_create(checksum, ddk, ddp, &bp);
1256
1257                 scn->scn_visited_this_txg++;
1258                 scan_funcs[scn->scn_phys.scn_func](scn->scn_dp, &bp, &zb);
1259         }
1260 }
1261
1262 static void
1263 dsl_scan_visit(dsl_scan_t *scn, dmu_tx_t *tx)
1264 {
1265         dsl_pool_t *dp = scn->scn_dp;
1266         zap_cursor_t *zc;
1267         zap_attribute_t *za;
1268
1269         if (scn->scn_phys.scn_ddt_bookmark.ddb_class <=
1270             scn->scn_phys.scn_ddt_class_max) {
1271                 scn->scn_phys.scn_cur_min_txg = scn->scn_phys.scn_min_txg;
1272                 scn->scn_phys.scn_cur_max_txg = scn->scn_phys.scn_max_txg;
1273                 dsl_scan_ddt(scn, tx);
1274                 if (scn->scn_pausing)
1275                         return;
1276         }
1277
1278         if (scn->scn_phys.scn_bookmark.zb_objset == DMU_META_OBJSET) {
1279                 /* First do the MOS & ORIGIN */
1280
1281                 scn->scn_phys.scn_cur_min_txg = scn->scn_phys.scn_min_txg;
1282                 scn->scn_phys.scn_cur_max_txg = scn->scn_phys.scn_max_txg;
1283                 dsl_scan_visit_rootbp(scn, NULL,
1284                     &dp->dp_meta_rootbp, tx);
1285                 spa_set_rootblkptr(dp->dp_spa, &dp->dp_meta_rootbp);
1286                 if (scn->scn_pausing)
1287                         return;
1288
1289                 if (spa_version(dp->dp_spa) < SPA_VERSION_DSL_SCRUB) {
1290                         VERIFY(0 == dmu_objset_find_spa(dp->dp_spa,
1291                             NULL, enqueue_cb, tx, DS_FIND_CHILDREN));
1292                 } else {
1293                         dsl_scan_visitds(scn,
1294                             dp->dp_origin_snap->ds_object, tx);
1295                 }
1296                 ASSERT(!scn->scn_pausing);
1297         } else if (scn->scn_phys.scn_bookmark.zb_objset !=
1298             ZB_DESTROYED_OBJSET) {
1299                 /*
1300                  * If we were paused, continue from here.  Note if the
1301                  * ds we were paused on was deleted, the zb_objset may
1302                  * be -1, so we will skip this and find a new objset
1303                  * below.
1304                  */
1305                 dsl_scan_visitds(scn, scn->scn_phys.scn_bookmark.zb_objset, tx);
1306                 if (scn->scn_pausing)
1307                         return;
1308         }
1309
1310         /*
1311          * In case we were paused right at the end of the ds, zero the
1312          * bookmark so we don't think that we're still trying to resume.
1313          */
1314         bzero(&scn->scn_phys.scn_bookmark, sizeof (zbookmark_t));
1315         zc = kmem_alloc(sizeof(zap_cursor_t), KM_PUSHPAGE);
1316         za = kmem_alloc(sizeof(zap_attribute_t), KM_PUSHPAGE);
1317
1318         /* keep pulling things out of the zap-object-as-queue */
1319         while (zap_cursor_init(zc, dp->dp_meta_objset,
1320             scn->scn_phys.scn_queue_obj),
1321             zap_cursor_retrieve(zc, za) == 0) {
1322                 dsl_dataset_t *ds;
1323                 uint64_t dsobj;
1324
1325                 dsobj = strtonum(za->za_name, NULL);
1326                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
1327                     scn->scn_phys.scn_queue_obj, dsobj, tx));
1328
1329                 /* Set up min/max txg */
1330                 VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
1331                 if (za->za_first_integer != 0) {
1332                         scn->scn_phys.scn_cur_min_txg =
1333                             MAX(scn->scn_phys.scn_min_txg,
1334                             za->za_first_integer);
1335                 } else {
1336                         scn->scn_phys.scn_cur_min_txg =
1337                             MAX(scn->scn_phys.scn_min_txg,
1338                             ds->ds_phys->ds_prev_snap_txg);
1339                 }
1340                 scn->scn_phys.scn_cur_max_txg = dsl_scan_ds_maxtxg(ds);
1341                 dsl_dataset_rele(ds, FTAG);
1342
1343                 dsl_scan_visitds(scn, dsobj, tx);
1344                 zap_cursor_fini(zc);
1345                 if (scn->scn_pausing)
1346                         goto out;
1347         }
1348         zap_cursor_fini(zc);
1349 out:
1350         kmem_free(za, sizeof(zap_attribute_t));
1351         kmem_free(zc, sizeof(zap_cursor_t));
1352 }
1353
1354 static boolean_t
1355 dsl_scan_free_should_pause(dsl_scan_t *scn)
1356 {
1357         uint64_t elapsed_nanosecs;
1358
1359         elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
1360         return (elapsed_nanosecs / NANOSEC > zfs_txg_timeout ||
1361             (elapsed_nanosecs / MICROSEC > zfs_free_min_time_ms &&
1362             txg_sync_waiting(scn->scn_dp)) ||
1363             spa_shutting_down(scn->scn_dp->dp_spa));
1364 }
1365
1366 static int
1367 dsl_scan_free_block_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
1368 {
1369         dsl_scan_t *scn = arg;
1370
1371         if (!scn->scn_is_bptree ||
1372             (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_OBJSET)) {
1373                 if (dsl_scan_free_should_pause(scn))
1374                         return (ERESTART);
1375         }
1376
1377         zio_nowait(zio_free_sync(scn->scn_zio_root, scn->scn_dp->dp_spa,
1378             dmu_tx_get_txg(tx), bp, 0));
1379         dsl_dir_diduse_space(tx->tx_pool->dp_free_dir, DD_USED_HEAD,
1380             -bp_get_dsize_sync(scn->scn_dp->dp_spa, bp),
1381             -BP_GET_PSIZE(bp), -BP_GET_UCSIZE(bp), tx);
1382         scn->scn_visited_this_txg++;
1383         return (0);
1384 }
1385
1386 boolean_t
1387 dsl_scan_active(dsl_scan_t *scn)
1388 {
1389         spa_t *spa = scn->scn_dp->dp_spa;
1390         uint64_t used = 0, comp, uncomp;
1391
1392         if (spa->spa_load_state != SPA_LOAD_NONE)
1393                 return (B_FALSE);
1394         if (spa_shutting_down(spa))
1395                 return (B_FALSE);
1396
1397         if (scn->scn_phys.scn_state == DSS_SCANNING)
1398                 return (B_TRUE);
1399
1400         if (spa_feature_is_active(spa,
1401             &spa_feature_table[SPA_FEATURE_ASYNC_DESTROY])) {
1402                 return (B_TRUE);
1403         }
1404         if (spa_version(scn->scn_dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
1405                 (void) bpobj_space(&scn->scn_dp->dp_free_bpobj,
1406                     &used, &comp, &uncomp);
1407         }
1408         return (used != 0);
1409 }
1410
1411 void
1412 dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t *tx)
1413 {
1414         dsl_scan_t *scn = dp->dp_scan;
1415         spa_t *spa = dp->dp_spa;
1416         int err;
1417
1418         /*
1419          * Check for scn_restart_txg before checking spa_load_state, so
1420          * that we can restart an old-style scan while the pool is being
1421          * imported (see dsl_scan_init).
1422          */
1423         if (scn->scn_restart_txg != 0 &&
1424             scn->scn_restart_txg <= tx->tx_txg) {
1425                 pool_scan_func_t func = POOL_SCAN_SCRUB;
1426                 dsl_scan_done(scn, B_FALSE, tx);
1427                 if (vdev_resilver_needed(spa->spa_root_vdev, NULL, NULL))
1428                         func = POOL_SCAN_RESILVER;
1429                 zfs_dbgmsg("restarting scan func=%u txg=%llu",
1430                     func, tx->tx_txg);
1431                 dsl_scan_setup_sync(scn, &func, tx);
1432         }
1433
1434         if (!dsl_scan_active(scn) ||
1435             spa_sync_pass(dp->dp_spa) > 1)
1436                 return;
1437
1438         scn->scn_visited_this_txg = 0;
1439         scn->scn_pausing = B_FALSE;
1440         scn->scn_sync_start_time = gethrtime();
1441         spa->spa_scrub_active = B_TRUE;
1442
1443         /*
1444          * First process the free list.  If we pause the free, don't do
1445          * any scanning.  This ensures that there is no free list when
1446          * we are scanning, so the scan code doesn't have to worry about
1447          * traversing it.
1448          */
1449         if (spa_version(dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
1450                 scn->scn_is_bptree = B_FALSE;
1451                 scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
1452                     NULL, ZIO_FLAG_MUSTSUCCEED);
1453                 err = bpobj_iterate(&dp->dp_free_bpobj,
1454                     dsl_scan_free_block_cb, scn, tx);
1455                 VERIFY3U(0, ==, zio_wait(scn->scn_zio_root));
1456
1457                 if (err == 0 && spa_feature_is_active(spa,
1458                     &spa_feature_table[SPA_FEATURE_ASYNC_DESTROY])) {
1459                         scn->scn_is_bptree = B_TRUE;
1460                         scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
1461                             NULL, ZIO_FLAG_MUSTSUCCEED);
1462                         err = bptree_iterate(dp->dp_meta_objset,
1463                             dp->dp_bptree_obj, B_TRUE, dsl_scan_free_block_cb,
1464                             scn, tx);
1465                         VERIFY3U(0, ==, zio_wait(scn->scn_zio_root));
1466                         if (err != 0)
1467                                 return;
1468
1469                         /* disable async destroy feature */
1470                         spa_feature_decr(spa,
1471                             &spa_feature_table[SPA_FEATURE_ASYNC_DESTROY], tx);
1472                         ASSERT(!spa_feature_is_active(spa,
1473                             &spa_feature_table[SPA_FEATURE_ASYNC_DESTROY]));
1474                         VERIFY3U(0, ==, zap_remove(dp->dp_meta_objset,
1475                             DMU_POOL_DIRECTORY_OBJECT,
1476                             DMU_POOL_BPTREE_OBJ, tx));
1477                         VERIFY3U(0, ==, bptree_free(dp->dp_meta_objset,
1478                             dp->dp_bptree_obj, tx));
1479                         dp->dp_bptree_obj = 0;
1480                 }
1481                 if (scn->scn_visited_this_txg) {
1482                         zfs_dbgmsg("freed %llu blocks in %llums from "
1483                             "free_bpobj/bptree txg %llu",
1484                             (longlong_t)scn->scn_visited_this_txg,
1485                             (longlong_t)
1486                             (gethrtime() - scn->scn_sync_start_time) / MICROSEC,
1487                             (longlong_t)tx->tx_txg);
1488                         scn->scn_visited_this_txg = 0;
1489                         /*
1490                          * Re-sync the ddt so that we can further modify
1491                          * it when doing bprewrite.
1492                          */
1493                         ddt_sync(spa, tx->tx_txg);
1494                 }
1495                 if (err == ERESTART)
1496                         return;
1497         }
1498
1499         if (scn->scn_phys.scn_state != DSS_SCANNING)
1500                 return;
1501
1502         if (scn->scn_phys.scn_ddt_bookmark.ddb_class <=
1503             scn->scn_phys.scn_ddt_class_max) {
1504                 zfs_dbgmsg("doing scan sync txg %llu; "
1505                     "ddt bm=%llu/%llu/%llu/%llx",
1506                     (longlong_t)tx->tx_txg,
1507                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_class,
1508                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_type,
1509                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_checksum,
1510                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_cursor);
1511                 ASSERT(scn->scn_phys.scn_bookmark.zb_objset == 0);
1512                 ASSERT(scn->scn_phys.scn_bookmark.zb_object == 0);
1513                 ASSERT(scn->scn_phys.scn_bookmark.zb_level == 0);
1514                 ASSERT(scn->scn_phys.scn_bookmark.zb_blkid == 0);
1515         } else {
1516                 zfs_dbgmsg("doing scan sync txg %llu; bm=%llu/%llu/%llu/%llu",
1517                     (longlong_t)tx->tx_txg,
1518                     (longlong_t)scn->scn_phys.scn_bookmark.zb_objset,
1519                     (longlong_t)scn->scn_phys.scn_bookmark.zb_object,
1520                     (longlong_t)scn->scn_phys.scn_bookmark.zb_level,
1521                     (longlong_t)scn->scn_phys.scn_bookmark.zb_blkid);
1522         }
1523
1524         scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
1525             NULL, ZIO_FLAG_CANFAIL);
1526         dsl_scan_visit(scn, tx);
1527         (void) zio_wait(scn->scn_zio_root);
1528         scn->scn_zio_root = NULL;
1529
1530         zfs_dbgmsg("visited %llu blocks in %llums",
1531             (longlong_t)scn->scn_visited_this_txg,
1532             (longlong_t)(gethrtime() - scn->scn_sync_start_time) / MICROSEC);
1533
1534         if (!scn->scn_pausing) {
1535                 /* finished with scan. */
1536                 zfs_dbgmsg("finished scan txg %llu", (longlong_t)tx->tx_txg);
1537                 dsl_scan_done(scn, B_TRUE, tx);
1538         }
1539
1540         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
1541                 mutex_enter(&spa->spa_scrub_lock);
1542                 while (spa->spa_scrub_inflight > 0) {
1543                         cv_wait(&spa->spa_scrub_io_cv,
1544                             &spa->spa_scrub_lock);
1545                 }
1546                 mutex_exit(&spa->spa_scrub_lock);
1547         }
1548
1549         dsl_scan_sync_state(scn, tx);
1550 }
1551
1552 /*
1553  * This will start a new scan, or restart an existing one.
1554  */
1555 void
1556 dsl_resilver_restart(dsl_pool_t *dp, uint64_t txg)
1557 {
1558         if (txg == 0) {
1559                 dmu_tx_t *tx;
1560                 tx = dmu_tx_create_dd(dp->dp_mos_dir);
1561                 VERIFY(0 == dmu_tx_assign(tx, TXG_WAIT));
1562
1563                 txg = dmu_tx_get_txg(tx);
1564                 dp->dp_scan->scn_restart_txg = txg;
1565                 dmu_tx_commit(tx);
1566         } else {
1567                 dp->dp_scan->scn_restart_txg = txg;
1568         }
1569         zfs_dbgmsg("restarting resilver txg=%llu", txg);
1570 }
1571
1572 boolean_t
1573 dsl_scan_resilvering(dsl_pool_t *dp)
1574 {
1575         return (dp->dp_scan->scn_phys.scn_state == DSS_SCANNING &&
1576             dp->dp_scan->scn_phys.scn_func == POOL_SCAN_RESILVER);
1577 }
1578
1579 /*
1580  * scrub consumers
1581  */
1582
1583 static void
1584 count_block(zfs_all_blkstats_t *zab, const blkptr_t *bp)
1585 {
1586         int i;
1587
1588         /*
1589          * If we resume after a reboot, zab will be NULL; don't record
1590          * incomplete stats in that case.
1591          */
1592         if (zab == NULL)
1593                 return;
1594
1595         for (i = 0; i < 4; i++) {
1596                 int l = (i < 2) ? BP_GET_LEVEL(bp) : DN_MAX_LEVELS;
1597                 int t = (i & 1) ? BP_GET_TYPE(bp) : DMU_OT_TOTAL;
1598                 int equal;
1599                 zfs_blkstat_t *zb;
1600
1601                 if (t & DMU_OT_NEWTYPE)
1602                         t = DMU_OT_OTHER;
1603
1604                 zb = &zab->zab_type[l][t];
1605                 zb->zb_count++;
1606                 zb->zb_asize += BP_GET_ASIZE(bp);
1607                 zb->zb_lsize += BP_GET_LSIZE(bp);
1608                 zb->zb_psize += BP_GET_PSIZE(bp);
1609                 zb->zb_gangs += BP_COUNT_GANG(bp);
1610
1611                 switch (BP_GET_NDVAS(bp)) {
1612                 case 2:
1613                         if (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1614                             DVA_GET_VDEV(&bp->blk_dva[1]))
1615                                 zb->zb_ditto_2_of_2_samevdev++;
1616                         break;
1617                 case 3:
1618                         equal = (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1619                             DVA_GET_VDEV(&bp->blk_dva[1])) +
1620                             (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1621                             DVA_GET_VDEV(&bp->blk_dva[2])) +
1622                             (DVA_GET_VDEV(&bp->blk_dva[1]) ==
1623                             DVA_GET_VDEV(&bp->blk_dva[2]));
1624                         if (equal == 1)
1625                                 zb->zb_ditto_2_of_3_samevdev++;
1626                         else if (equal == 3)
1627                                 zb->zb_ditto_3_of_3_samevdev++;
1628                         break;
1629                 }
1630         }
1631 }
1632
1633 static void
1634 dsl_scan_scrub_done(zio_t *zio)
1635 {
1636         spa_t *spa = zio->io_spa;
1637
1638         zio_data_buf_free(zio->io_data, zio->io_size);
1639
1640         mutex_enter(&spa->spa_scrub_lock);
1641         spa->spa_scrub_inflight--;
1642         cv_broadcast(&spa->spa_scrub_io_cv);
1643
1644         if (zio->io_error && (zio->io_error != ECKSUM ||
1645             !(zio->io_flags & ZIO_FLAG_SPECULATIVE))) {
1646                 spa->spa_dsl_pool->dp_scan->scn_phys.scn_errors++;
1647         }
1648         mutex_exit(&spa->spa_scrub_lock);
1649 }
1650
1651 static int
1652 dsl_scan_scrub_cb(dsl_pool_t *dp,
1653     const blkptr_t *bp, const zbookmark_t *zb)
1654 {
1655         dsl_scan_t *scn = dp->dp_scan;
1656         size_t size = BP_GET_PSIZE(bp);
1657         spa_t *spa = dp->dp_spa;
1658         uint64_t phys_birth = BP_PHYSICAL_BIRTH(bp);
1659         boolean_t needs_io = B_FALSE;
1660         int zio_flags = ZIO_FLAG_SCAN_THREAD | ZIO_FLAG_RAW | ZIO_FLAG_CANFAIL;
1661         int zio_priority = 0;
1662         int scan_delay = 0;
1663         int d;
1664
1665         if (phys_birth <= scn->scn_phys.scn_min_txg ||
1666             phys_birth >= scn->scn_phys.scn_max_txg)
1667                 return (0);
1668
1669         count_block(dp->dp_blkstats, bp);
1670
1671         ASSERT(DSL_SCAN_IS_SCRUB_RESILVER(scn));
1672         if (scn->scn_phys.scn_func == POOL_SCAN_SCRUB) {
1673                 zio_flags |= ZIO_FLAG_SCRUB;
1674                 zio_priority = ZIO_PRIORITY_SCRUB;
1675                 needs_io = B_TRUE;
1676                 scan_delay = zfs_scrub_delay;
1677         } else if (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) {
1678                 zio_flags |= ZIO_FLAG_RESILVER;
1679                 zio_priority = ZIO_PRIORITY_RESILVER;
1680                 needs_io = B_FALSE;
1681                 scan_delay = zfs_resilver_delay;
1682         }
1683
1684         /* If it's an intent log block, failure is expected. */
1685         if (zb->zb_level == ZB_ZIL_LEVEL)
1686                 zio_flags |= ZIO_FLAG_SPECULATIVE;
1687
1688         for (d = 0; d < BP_GET_NDVAS(bp); d++) {
1689                 vdev_t *vd = vdev_lookup_top(spa,
1690                     DVA_GET_VDEV(&bp->blk_dva[d]));
1691
1692                 /*
1693                  * Keep track of how much data we've examined so that
1694                  * zpool(1M) status can make useful progress reports.
1695                  */
1696                 scn->scn_phys.scn_examined += DVA_GET_ASIZE(&bp->blk_dva[d]);
1697                 spa->spa_scan_pass_exam += DVA_GET_ASIZE(&bp->blk_dva[d]);
1698
1699                 /* if it's a resilver, this may not be in the target range */
1700                 if (!needs_io) {
1701                         if (DVA_GET_GANG(&bp->blk_dva[d])) {
1702                                 /*
1703                                  * Gang members may be spread across multiple
1704                                  * vdevs, so the best estimate we have is the
1705                                  * scrub range, which has already been checked.
1706                                  * XXX -- it would be better to change our
1707                                  * allocation policy to ensure that all
1708                                  * gang members reside on the same vdev.
1709                                  */
1710                                 needs_io = B_TRUE;
1711                         } else {
1712                                 needs_io = vdev_dtl_contains(vd, DTL_PARTIAL,
1713                                     phys_birth, 1);
1714                         }
1715                 }
1716         }
1717
1718         if (needs_io && !zfs_no_scrub_io) {
1719                 vdev_t *rvd = spa->spa_root_vdev;
1720                 uint64_t maxinflight = rvd->vdev_children * zfs_top_maxinflight;
1721                 void *data = zio_data_buf_alloc(size);
1722
1723                 mutex_enter(&spa->spa_scrub_lock);
1724                 while (spa->spa_scrub_inflight >= maxinflight)
1725                         cv_wait(&spa->spa_scrub_io_cv, &spa->spa_scrub_lock);
1726                 spa->spa_scrub_inflight++;
1727                 mutex_exit(&spa->spa_scrub_lock);
1728
1729                 /*
1730                  * If we're seeing recent (zfs_scan_idle) "important" I/Os
1731                  * then throttle our workload to limit the impact of a scan.
1732                  */
1733                 if (ddi_get_lbolt64() - spa->spa_last_io <= zfs_scan_idle)
1734                         delay(scan_delay);
1735
1736                 zio_nowait(zio_read(NULL, spa, bp, data, size,
1737                     dsl_scan_scrub_done, NULL, zio_priority,
1738                     zio_flags, zb));
1739         }
1740
1741         /* do not relocate this block */
1742         return (0);
1743 }
1744
1745 int
1746 dsl_scan(dsl_pool_t *dp, pool_scan_func_t func)
1747 {
1748         spa_t *spa = dp->dp_spa;
1749
1750         /*
1751          * Purge all vdev caches and probe all devices.  We do this here
1752          * rather than in sync context because this requires a writer lock
1753          * on the spa_config lock, which we can't do from sync context.  The
1754          * spa_scrub_reopen flag indicates that vdev_open() should not
1755          * attempt to start another scrub.
1756          */
1757         spa_vdev_state_enter(spa, SCL_NONE);
1758         spa->spa_scrub_reopen = B_TRUE;
1759         vdev_reopen(spa->spa_root_vdev);
1760         spa->spa_scrub_reopen = B_FALSE;
1761         (void) spa_vdev_state_exit(spa, NULL, 0);
1762
1763         return (dsl_sync_task_do(dp, dsl_scan_setup_check,
1764             dsl_scan_setup_sync, dp->dp_scan, &func, 0));
1765 }
1766
1767 #if defined(_KERNEL) && defined(HAVE_SPL)
1768 module_param(zfs_top_maxinflight, int, 0644);
1769 MODULE_PARM_DESC(zfs_top_maxinflight, "Max I/Os per top-level");
1770
1771 module_param(zfs_resilver_delay, int, 0644);
1772 MODULE_PARM_DESC(zfs_resilver_delay, "Number of ticks to delay resilver");
1773
1774 module_param(zfs_scrub_delay, int, 0644);
1775 MODULE_PARM_DESC(zfs_scrub_delay, "Number of ticks to delay scrub");
1776
1777 module_param(zfs_scan_idle, int, 0644);
1778 MODULE_PARM_DESC(zfs_scan_idle, "Idle window in clock ticks");
1779
1780 module_param(zfs_scan_min_time_ms, int, 0644);
1781 MODULE_PARM_DESC(zfs_scan_min_time_ms, "Min millisecs to scrub per txg");
1782
1783 module_param(zfs_free_min_time_ms, int, 0644);
1784 MODULE_PARM_DESC(zfs_free_min_time_ms, "Min millisecs to free per txg");
1785
1786 module_param(zfs_resilver_min_time_ms, int, 0644);
1787 MODULE_PARM_DESC(zfs_resilver_min_time_ms, "Min millisecs to resilver per txg");
1788
1789 module_param(zfs_no_scrub_io, int, 0644);
1790 MODULE_PARM_DESC(zfs_no_scrub_io, "Set to disable scrub I/O");
1791
1792 module_param(zfs_no_scrub_prefetch, int, 0644);
1793 MODULE_PARM_DESC(zfs_no_scrub_prefetch, "Set to disable scrub prefetching");
1794 #endif