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) 2011, 2015 by Delphix. All rights reserved.
  24  * Copyright 2016 Gary Mills
  25  */
  26 
  27 #include <sys/dsl_scan.h>
  28 #include <sys/dsl_pool.h>
  29 #include <sys/dsl_dataset.h>
  30 #include <sys/dsl_prop.h>
  31 #include <sys/dsl_dir.h>
  32 #include <sys/dsl_synctask.h>
  33 #include <sys/dnode.h>
  34 #include <sys/dmu_tx.h>
  35 #include <sys/dmu_objset.h>
  36 #include <sys/arc.h>
  37 #include <sys/zap.h>
  38 #include <sys/zio.h>
  39 #include <sys/zfs_context.h>
  40 #include <sys/fs/zfs.h>
  41 #include <sys/zfs_znode.h>
  42 #include <sys/spa_impl.h>
  43 #include <sys/vdev_impl.h>
  44 #include <sys/zil_impl.h>
  45 #include <sys/zio_checksum.h>
  46 #include <sys/ddt.h>
  47 #include <sys/sa.h>
  48 #include <sys/sa_impl.h>
  49 #include <sys/zfeature.h>
  50 #ifdef _KERNEL
  51 #include <sys/zfs_vfsops.h>
  52 #endif
  53 
  54 typedef int (scan_cb_t)(dsl_pool_t *, const blkptr_t *,
  55     const zbookmark_phys_t *);
  56 
  57 static scan_cb_t dsl_scan_scrub_cb;
  58 static void dsl_scan_cancel_sync(void *, dmu_tx_t *);
  59 static void dsl_scan_sync_state(dsl_scan_t *, dmu_tx_t *);
  60 static boolean_t dsl_scan_restarting(dsl_scan_t *, dmu_tx_t *);
  61 
  62 int zfs_top_maxinflight = 32;           /* maximum I/Os per top-level */
  63 int zfs_resilver_delay = 2;             /* number of ticks to delay resilver */
  64 int zfs_scrub_delay = 4;                /* number of ticks to delay scrub */
  65 int zfs_scan_idle = 50;                 /* idle window in clock ticks */
  66 
  67 int zfs_scan_min_time_ms = 1000; /* min millisecs to scrub per txg */
  68 int zfs_free_min_time_ms = 1000; /* min millisecs to free per txg */
  69 int zfs_resilver_min_time_ms = 3000; /* min millisecs to resilver per txg */
  70 boolean_t zfs_no_scrub_io = B_FALSE; /* set to disable scrub i/o */
  71 boolean_t zfs_no_scrub_prefetch = B_FALSE; /* set to disable scrub prefetch */
  72 enum ddt_class zfs_scrub_ddt_class_max = DDT_CLASS_DUPLICATE;
  73 int dsl_scan_delay_completion = B_FALSE; /* set to delay scan completion */
  74 /* max number of blocks to free in a single TXG */
  75 uint64_t zfs_free_max_blocks = UINT64_MAX;
  76 
  77 #define DSL_SCAN_IS_SCRUB_RESILVER(scn) \
  78         ((scn)->scn_phys.scn_func == POOL_SCAN_SCRUB || \
  79         (scn)->scn_phys.scn_func == POOL_SCAN_RESILVER)
  80 
  81 extern int zfs_txg_timeout;
  82 
  83 /*
  84  * Enable/disable the processing of the free_bpobj object.
  85  */
  86 boolean_t zfs_free_bpobj_enabled = B_TRUE;
  87 
  88 /* the order has to match pool_scan_type */
  89 static scan_cb_t *scan_funcs[POOL_SCAN_FUNCS] = {
  90         NULL,
  91         dsl_scan_scrub_cb,      /* POOL_SCAN_SCRUB */
  92         dsl_scan_scrub_cb,      /* POOL_SCAN_RESILVER */
  93 };
  94 
  95 int
  96 dsl_scan_init(dsl_pool_t *dp, uint64_t txg)
  97 {
  98         int err;
  99         dsl_scan_t *scn;
 100         spa_t *spa = dp->dp_spa;
 101         uint64_t f;
 102 
 103         scn = dp->dp_scan = kmem_zalloc(sizeof (dsl_scan_t), KM_SLEEP);
 104         scn->scn_dp = dp;
 105 
 106         /*
 107          * It's possible that we're resuming a scan after a reboot so
 108          * make sure that the scan_async_destroying flag is initialized
 109          * appropriately.
 110          */
 111         ASSERT(!scn->scn_async_destroying);
 112         scn->scn_async_destroying = spa_feature_is_active(dp->dp_spa,
 113             SPA_FEATURE_ASYNC_DESTROY);
 114 
 115         err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 116             "scrub_func", sizeof (uint64_t), 1, &f);
 117         if (err == 0) {
 118                 /*
 119                  * There was an old-style scrub in progress.  Restart a
 120                  * new-style scrub from the beginning.
 121                  */
 122                 scn->scn_restart_txg = txg;
 123                 zfs_dbgmsg("old-style scrub was in progress; "
 124                     "restarting new-style scrub in txg %llu",
 125                     scn->scn_restart_txg);
 126 
 127                 /*
 128                  * Load the queue obj from the old location so that it
 129                  * can be freed by dsl_scan_done().
 130                  */
 131                 (void) zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 132                     "scrub_queue", sizeof (uint64_t), 1,
 133                     &scn->scn_phys.scn_queue_obj);
 134         } else {
 135                 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 136                     DMU_POOL_SCAN, sizeof (uint64_t), SCAN_PHYS_NUMINTS,
 137                     &scn->scn_phys);
 138                 if (err == ENOENT)
 139                         return (0);
 140                 else if (err)
 141                         return (err);
 142 
 143                 if (scn->scn_phys.scn_state == DSS_SCANNING &&
 144                     spa_prev_software_version(dp->dp_spa) < SPA_VERSION_SCAN) {
 145                         /*
 146                          * A new-type scrub was in progress on an old
 147                          * pool, and the pool was accessed by old
 148                          * software.  Restart from the beginning, since
 149                          * the old software may have changed the pool in
 150                          * the meantime.
 151                          */
 152                         scn->scn_restart_txg = txg;
 153                         zfs_dbgmsg("new-style scrub was modified "
 154                             "by old software; restarting in txg %llu",
 155                             scn->scn_restart_txg);
 156                 }
 157         }
 158 
 159         spa_scan_stat_init(spa);
 160         return (0);
 161 }
 162 
 163 void
 164 dsl_scan_fini(dsl_pool_t *dp)
 165 {
 166         if (dp->dp_scan) {
 167                 kmem_free(dp->dp_scan, sizeof (dsl_scan_t));
 168                 dp->dp_scan = NULL;
 169         }
 170 }
 171 
 172 /* ARGSUSED */
 173 static int
 174 dsl_scan_setup_check(void *arg, dmu_tx_t *tx)
 175 {
 176         dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan;
 177 
 178         if (scn->scn_phys.scn_state == DSS_SCANNING)
 179                 return (SET_ERROR(EBUSY));
 180 
 181         return (0);
 182 }
 183 
 184 static void
 185 dsl_scan_setup_sync(void *arg, dmu_tx_t *tx)
 186 {
 187         dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan;
 188         pool_scan_func_t *funcp = arg;
 189         dmu_object_type_t ot = 0;
 190         dsl_pool_t *dp = scn->scn_dp;
 191         spa_t *spa = dp->dp_spa;
 192 
 193         ASSERT(scn->scn_phys.scn_state != DSS_SCANNING);
 194         ASSERT(*funcp > POOL_SCAN_NONE && *funcp < POOL_SCAN_FUNCS);
 195         bzero(&scn->scn_phys, sizeof (scn->scn_phys));
 196         scn->scn_phys.scn_func = *funcp;
 197         scn->scn_phys.scn_state = DSS_SCANNING;
 198         scn->scn_phys.scn_min_txg = 0;
 199         scn->scn_phys.scn_max_txg = tx->tx_txg;
 200         scn->scn_phys.scn_ddt_class_max = DDT_CLASSES - 1; /* the entire DDT */
 201         scn->scn_phys.scn_start_time = gethrestime_sec();
 202         scn->scn_phys.scn_errors = 0;
 203         scn->scn_phys.scn_to_examine = spa->spa_root_vdev->vdev_stat.vs_alloc;
 204         scn->scn_restart_txg = 0;
 205         scn->scn_done_txg = 0;
 206         spa_scan_stat_init(spa);
 207 
 208         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
 209                 scn->scn_phys.scn_ddt_class_max = zfs_scrub_ddt_class_max;
 210 
 211                 /* rewrite all disk labels */
 212                 vdev_config_dirty(spa->spa_root_vdev);
 213 
 214                 if (vdev_resilver_needed(spa->spa_root_vdev,
 215                     &scn->scn_phys.scn_min_txg, &scn->scn_phys.scn_max_txg)) {
 216                         spa_event_notify(spa, NULL, ESC_ZFS_RESILVER_START);
 217                 } else {
 218                         spa_event_notify(spa, NULL, ESC_ZFS_SCRUB_START);
 219                 }
 220 
 221                 spa->spa_scrub_started = B_TRUE;
 222                 /*
 223                  * If this is an incremental scrub, limit the DDT scrub phase
 224                  * to just the auto-ditto class (for correctness); the rest
 225                  * of the scrub should go faster using top-down pruning.
 226                  */
 227                 if (scn->scn_phys.scn_min_txg > TXG_INITIAL)
 228                         scn->scn_phys.scn_ddt_class_max = DDT_CLASS_DITTO;
 229 
 230         }
 231 
 232         /* back to the generic stuff */
 233 
 234         if (dp->dp_blkstats == NULL) {
 235                 dp->dp_blkstats =
 236                     kmem_alloc(sizeof (zfs_all_blkstats_t), KM_SLEEP);
 237         }
 238         bzero(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
 239 
 240         if (spa_version(spa) < SPA_VERSION_DSL_SCRUB)
 241                 ot = DMU_OT_ZAP_OTHER;
 242 
 243         scn->scn_phys.scn_queue_obj = zap_create(dp->dp_meta_objset,
 244             ot ? ot : DMU_OT_SCAN_QUEUE, DMU_OT_NONE, 0, tx);
 245 
 246         dsl_scan_sync_state(scn, tx);
 247 
 248         spa_history_log_internal(spa, "scan setup", tx,
 249             "func=%u mintxg=%llu maxtxg=%llu",
 250             *funcp, scn->scn_phys.scn_min_txg, scn->scn_phys.scn_max_txg);
 251 }
 252 
 253 /* ARGSUSED */
 254 static void
 255 dsl_scan_done(dsl_scan_t *scn, boolean_t complete, dmu_tx_t *tx)
 256 {
 257         static const char *old_names[] = {
 258                 "scrub_bookmark",
 259                 "scrub_ddt_bookmark",
 260                 "scrub_ddt_class_max",
 261                 "scrub_queue",
 262                 "scrub_min_txg",
 263                 "scrub_max_txg",
 264                 "scrub_func",
 265                 "scrub_errors",
 266                 NULL
 267         };
 268 
 269         dsl_pool_t *dp = scn->scn_dp;
 270         spa_t *spa = dp->dp_spa;
 271         int i;
 272 
 273         /* Remove any remnants of an old-style scrub. */
 274         for (i = 0; old_names[i]; i++) {
 275                 (void) zap_remove(dp->dp_meta_objset,
 276                     DMU_POOL_DIRECTORY_OBJECT, old_names[i], tx);
 277         }
 278 
 279         if (scn->scn_phys.scn_queue_obj != 0) {
 280                 VERIFY(0 == dmu_object_free(dp->dp_meta_objset,
 281                     scn->scn_phys.scn_queue_obj, tx));
 282                 scn->scn_phys.scn_queue_obj = 0;
 283         }
 284 
 285         /*
 286          * If we were "restarted" from a stopped state, don't bother
 287          * with anything else.
 288          */
 289         if (scn->scn_phys.scn_state != DSS_SCANNING)
 290                 return;
 291 
 292         if (complete)
 293                 scn->scn_phys.scn_state = DSS_FINISHED;
 294         else
 295                 scn->scn_phys.scn_state = DSS_CANCELED;
 296 
 297         if (dsl_scan_restarting(scn, tx))
 298                 spa_history_log_internal(spa, "scan aborted, restarting", tx,
 299                     "errors=%llu", spa_get_errlog_size(spa));
 300         else if (!complete)
 301                 spa_history_log_internal(spa, "scan cancelled", tx,
 302                     "errors=%llu", spa_get_errlog_size(spa));
 303         else
 304                 spa_history_log_internal(spa, "scan done", tx,
 305                     "errors=%llu", spa_get_errlog_size(spa));
 306 
 307         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
 308                 mutex_enter(&spa->spa_scrub_lock);
 309                 while (spa->spa_scrub_inflight > 0) {
 310                         cv_wait(&spa->spa_scrub_io_cv,
 311                             &spa->spa_scrub_lock);
 312                 }
 313                 mutex_exit(&spa->spa_scrub_lock);
 314                 spa->spa_scrub_started = B_FALSE;
 315                 spa->spa_scrub_active = B_FALSE;
 316 
 317                 /*
 318                  * If the scrub/resilver completed, update all DTLs to
 319                  * reflect this.  Whether it succeeded or not, vacate
 320                  * all temporary scrub DTLs.
 321                  */
 322                 vdev_dtl_reassess(spa->spa_root_vdev, tx->tx_txg,
 323                     complete ? scn->scn_phys.scn_max_txg : 0, B_TRUE);
 324                 if (complete) {
 325                         spa_event_notify(spa, NULL, scn->scn_phys.scn_min_txg ?
 326                             ESC_ZFS_RESILVER_FINISH : ESC_ZFS_SCRUB_FINISH);
 327                 }
 328                 spa_errlog_rotate(spa);
 329 
 330                 /*
 331                  * We may have finished replacing a device.
 332                  * Let the async thread assess this and handle the detach.
 333                  */
 334                 spa_async_request(spa, SPA_ASYNC_RESILVER_DONE);
 335         }
 336 
 337         scn->scn_phys.scn_end_time = gethrestime_sec();
 338 }
 339 
 340 /* ARGSUSED */
 341 static int
 342 dsl_scan_cancel_check(void *arg, dmu_tx_t *tx)
 343 {
 344         dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan;
 345 
 346         if (scn->scn_phys.scn_state != DSS_SCANNING)
 347                 return (SET_ERROR(ENOENT));
 348         return (0);
 349 }
 350 
 351 /* ARGSUSED */
 352 static void
 353 dsl_scan_cancel_sync(void *arg, dmu_tx_t *tx)
 354 {
 355         dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan;
 356 
 357         dsl_scan_done(scn, B_FALSE, tx);
 358         dsl_scan_sync_state(scn, tx);
 359 }
 360 
 361 int
 362 dsl_scan_cancel(dsl_pool_t *dp)
 363 {
 364         return (dsl_sync_task(spa_name(dp->dp_spa), dsl_scan_cancel_check,
 365             dsl_scan_cancel_sync, NULL, 3, ZFS_SPACE_CHECK_RESERVED));
 366 }
 367 
 368 static void dsl_scan_visitbp(blkptr_t *bp, const zbookmark_phys_t *zb,
 369     dnode_phys_t *dnp, dsl_dataset_t *ds, dsl_scan_t *scn,
 370     dmu_objset_type_t ostype, dmu_tx_t *tx);
 371 static void dsl_scan_visitdnode(dsl_scan_t *, dsl_dataset_t *ds,
 372     dmu_objset_type_t ostype,
 373     dnode_phys_t *dnp, uint64_t object, dmu_tx_t *tx);
 374 
 375 void
 376 dsl_free(dsl_pool_t *dp, uint64_t txg, const blkptr_t *bp)
 377 {
 378         zio_free(dp->dp_spa, txg, bp);
 379 }
 380 
 381 void
 382 dsl_free_sync(zio_t *pio, dsl_pool_t *dp, uint64_t txg, const blkptr_t *bpp)
 383 {
 384         ASSERT(dsl_pool_sync_context(dp));
 385         zio_nowait(zio_free_sync(pio, dp->dp_spa, txg, bpp, pio->io_flags));
 386 }
 387 
 388 static uint64_t
 389 dsl_scan_ds_maxtxg(dsl_dataset_t *ds)
 390 {
 391         uint64_t smt = ds->ds_dir->dd_pool->dp_scan->scn_phys.scn_max_txg;
 392         if (ds->ds_is_snapshot)
 393                 return (MIN(smt, dsl_dataset_phys(ds)->ds_creation_txg));
 394         return (smt);
 395 }
 396 
 397 static void
 398 dsl_scan_sync_state(dsl_scan_t *scn, dmu_tx_t *tx)
 399 {
 400         VERIFY0(zap_update(scn->scn_dp->dp_meta_objset,
 401             DMU_POOL_DIRECTORY_OBJECT,
 402             DMU_POOL_SCAN, sizeof (uint64_t), SCAN_PHYS_NUMINTS,
 403             &scn->scn_phys, tx));
 404 }
 405 
 406 extern int zfs_vdev_async_write_active_min_dirty_percent;
 407 
 408 static boolean_t
 409 dsl_scan_check_pause(dsl_scan_t *scn, const zbookmark_phys_t *zb)
 410 {
 411         /* we never skip user/group accounting objects */
 412         if (zb && (int64_t)zb->zb_object < 0)
 413                 return (B_FALSE);
 414 
 415         if (scn->scn_pausing)
 416                 return (B_TRUE); /* we're already pausing */
 417 
 418         if (!ZB_IS_ZERO(&scn->scn_phys.scn_bookmark))
 419                 return (B_FALSE); /* we're resuming */
 420 
 421         /* We only know how to resume from level-0 blocks. */
 422         if (zb && zb->zb_level != 0)
 423                 return (B_FALSE);
 424 
 425         /*
 426          * We pause if:
 427          *  - we have scanned for the maximum time: an entire txg
 428          *    timeout (default 5 sec)
 429          *  or
 430          *  - we have scanned for at least the minimum time (default 1 sec
 431          *    for scrub, 3 sec for resilver), and either we have sufficient
 432          *    dirty data that we are starting to write more quickly
 433          *    (default 30%), or someone is explicitly waiting for this txg
 434          *    to complete.
 435          *  or
 436          *  - the spa is shutting down because this pool is being exported
 437          *    or the machine is rebooting.
 438          */
 439         int mintime = (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) ?
 440             zfs_resilver_min_time_ms : zfs_scan_min_time_ms;
 441         uint64_t elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
 442         int dirty_pct = scn->scn_dp->dp_dirty_total * 100 / zfs_dirty_data_max;
 443         if (elapsed_nanosecs / NANOSEC >= zfs_txg_timeout ||
 444             (NSEC2MSEC(elapsed_nanosecs) > mintime &&
 445             (txg_sync_waiting(scn->scn_dp) ||
 446             dirty_pct >= zfs_vdev_async_write_active_min_dirty_percent)) ||
 447             spa_shutting_down(scn->scn_dp->dp_spa)) {
 448                 if (zb) {
 449                         dprintf("pausing at bookmark %llx/%llx/%llx/%llx\n",
 450                             (longlong_t)zb->zb_objset,
 451                             (longlong_t)zb->zb_object,
 452                             (longlong_t)zb->zb_level,
 453                             (longlong_t)zb->zb_blkid);
 454                         scn->scn_phys.scn_bookmark = *zb;
 455                 }
 456                 dprintf("pausing at DDT bookmark %llx/%llx/%llx/%llx\n",
 457                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_class,
 458                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_type,
 459                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_checksum,
 460                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_cursor);
 461                 scn->scn_pausing = B_TRUE;
 462                 return (B_TRUE);
 463         }
 464         return (B_FALSE);
 465 }
 466 
 467 typedef struct zil_scan_arg {
 468         dsl_pool_t      *zsa_dp;
 469         zil_header_t    *zsa_zh;
 470 } zil_scan_arg_t;
 471 
 472 /* ARGSUSED */
 473 static int
 474 dsl_scan_zil_block(zilog_t *zilog, blkptr_t *bp, void *arg, uint64_t claim_txg)
 475 {
 476         zil_scan_arg_t *zsa = arg;
 477         dsl_pool_t *dp = zsa->zsa_dp;
 478         dsl_scan_t *scn = dp->dp_scan;
 479         zil_header_t *zh = zsa->zsa_zh;
 480         zbookmark_phys_t zb;
 481 
 482         if (BP_IS_HOLE(bp) || bp->blk_birth <= scn->scn_phys.scn_cur_min_txg)
 483                 return (0);
 484 
 485         /*
 486          * One block ("stubby") can be allocated a long time ago; we
 487          * want to visit that one because it has been allocated
 488          * (on-disk) even if it hasn't been claimed (even though for
 489          * scrub there's nothing to do to it).
 490          */
 491         if (claim_txg == 0 && bp->blk_birth >= spa_first_txg(dp->dp_spa))
 492                 return (0);
 493 
 494         SET_BOOKMARK(&zb, zh->zh_log.blk_cksum.zc_word[ZIL_ZC_OBJSET],
 495             ZB_ZIL_OBJECT, ZB_ZIL_LEVEL, bp->blk_cksum.zc_word[ZIL_ZC_SEQ]);
 496 
 497         VERIFY(0 == scan_funcs[scn->scn_phys.scn_func](dp, bp, &zb));
 498         return (0);
 499 }
 500 
 501 /* ARGSUSED */
 502 static int
 503 dsl_scan_zil_record(zilog_t *zilog, lr_t *lrc, void *arg, uint64_t claim_txg)
 504 {
 505         if (lrc->lrc_txtype == TX_WRITE) {
 506                 zil_scan_arg_t *zsa = arg;
 507                 dsl_pool_t *dp = zsa->zsa_dp;
 508                 dsl_scan_t *scn = dp->dp_scan;
 509                 zil_header_t *zh = zsa->zsa_zh;
 510                 lr_write_t *lr = (lr_write_t *)lrc;
 511                 blkptr_t *bp = &lr->lr_blkptr;
 512                 zbookmark_phys_t zb;
 513 
 514                 if (BP_IS_HOLE(bp) ||
 515                     bp->blk_birth <= scn->scn_phys.scn_cur_min_txg)
 516                         return (0);
 517 
 518                 /*
 519                  * birth can be < claim_txg if this record's txg is
 520                  * already txg sync'ed (but this log block contains
 521                  * other records that are not synced)
 522                  */
 523                 if (claim_txg == 0 || bp->blk_birth < claim_txg)
 524                         return (0);
 525 
 526                 SET_BOOKMARK(&zb, zh->zh_log.blk_cksum.zc_word[ZIL_ZC_OBJSET],
 527                     lr->lr_foid, ZB_ZIL_LEVEL,
 528                     lr->lr_offset / BP_GET_LSIZE(bp));
 529 
 530                 VERIFY(0 == scan_funcs[scn->scn_phys.scn_func](dp, bp, &zb));
 531         }
 532         return (0);
 533 }
 534 
 535 static void
 536 dsl_scan_zil(dsl_pool_t *dp, zil_header_t *zh)
 537 {
 538         uint64_t claim_txg = zh->zh_claim_txg;
 539         zil_scan_arg_t zsa = { dp, zh };
 540         zilog_t *zilog;
 541 
 542         /*
 543          * We only want to visit blocks that have been claimed but not yet
 544          * replayed (or, in read-only mode, blocks that *would* be claimed).
 545          */
 546         if (claim_txg == 0 && spa_writeable(dp->dp_spa))
 547                 return;
 548 
 549         zilog = zil_alloc(dp->dp_meta_objset, zh);
 550 
 551         (void) zil_parse(zilog, dsl_scan_zil_block, dsl_scan_zil_record, &zsa,
 552             claim_txg);
 553 
 554         zil_free(zilog);
 555 }
 556 
 557 /* ARGSUSED */
 558 static void
 559 dsl_scan_prefetch(dsl_scan_t *scn, arc_buf_t *buf, blkptr_t *bp,
 560     uint64_t objset, uint64_t object, uint64_t blkid)
 561 {
 562         zbookmark_phys_t czb;
 563         arc_flags_t flags = ARC_FLAG_NOWAIT | ARC_FLAG_PREFETCH;
 564 
 565         if (zfs_no_scrub_prefetch)
 566                 return;
 567 
 568         if (BP_IS_HOLE(bp) || bp->blk_birth <= scn->scn_phys.scn_min_txg ||
 569             (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_DNODE))
 570                 return;
 571 
 572         SET_BOOKMARK(&czb, objset, object, BP_GET_LEVEL(bp), blkid);
 573 
 574         (void) arc_read(scn->scn_zio_root, scn->scn_dp->dp_spa, bp,
 575             NULL, NULL, ZIO_PRIORITY_ASYNC_READ,
 576             ZIO_FLAG_CANFAIL | ZIO_FLAG_SCAN_THREAD, &flags, &czb);
 577 }
 578 
 579 static boolean_t
 580 dsl_scan_check_resume(dsl_scan_t *scn, const dnode_phys_t *dnp,
 581     const zbookmark_phys_t *zb)
 582 {
 583         /*
 584          * We never skip over user/group accounting objects (obj<0)
 585          */
 586         if (!ZB_IS_ZERO(&scn->scn_phys.scn_bookmark) &&
 587             (int64_t)zb->zb_object >= 0) {
 588                 /*
 589                  * If we already visited this bp & everything below (in
 590                  * a prior txg sync), don't bother doing it again.
 591                  */
 592                 if (zbookmark_subtree_completed(dnp, zb,
 593                     &scn->scn_phys.scn_bookmark))
 594                         return (B_TRUE);
 595 
 596                 /*
 597                  * If we found the block we're trying to resume from, or
 598                  * we went past it to a different object, zero it out to
 599                  * indicate that it's OK to start checking for pausing
 600                  * again.
 601                  */
 602                 if (bcmp(zb, &scn->scn_phys.scn_bookmark, sizeof (*zb)) == 0 ||
 603                     zb->zb_object > scn->scn_phys.scn_bookmark.zb_object) {
 604                         dprintf("resuming at %llx/%llx/%llx/%llx\n",
 605                             (longlong_t)zb->zb_objset,
 606                             (longlong_t)zb->zb_object,
 607                             (longlong_t)zb->zb_level,
 608                             (longlong_t)zb->zb_blkid);
 609                         bzero(&scn->scn_phys.scn_bookmark, sizeof (*zb));
 610                 }
 611         }
 612         return (B_FALSE);
 613 }
 614 
 615 /*
 616  * Return nonzero on i/o error.
 617  * Return new buf to write out in *bufp.
 618  */
 619 static int
 620 dsl_scan_recurse(dsl_scan_t *scn, dsl_dataset_t *ds, dmu_objset_type_t ostype,
 621     dnode_phys_t *dnp, const blkptr_t *bp,
 622     const zbookmark_phys_t *zb, dmu_tx_t *tx)
 623 {
 624         dsl_pool_t *dp = scn->scn_dp;
 625         int zio_flags = ZIO_FLAG_CANFAIL | ZIO_FLAG_SCAN_THREAD;
 626         int err;
 627 
 628         if (BP_GET_LEVEL(bp) > 0) {
 629                 arc_flags_t flags = ARC_FLAG_WAIT;
 630                 int i;
 631                 blkptr_t *cbp;
 632                 int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT;
 633                 arc_buf_t *buf;
 634 
 635                 err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, &buf,
 636                     ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
 637                 if (err) {
 638                         scn->scn_phys.scn_errors++;
 639                         return (err);
 640                 }
 641                 for (i = 0, cbp = buf->b_data; i < epb; i++, cbp++) {
 642                         dsl_scan_prefetch(scn, buf, cbp, zb->zb_objset,
 643                             zb->zb_object, zb->zb_blkid * epb + i);
 644                 }
 645                 for (i = 0, cbp = buf->b_data; i < epb; i++, cbp++) {
 646                         zbookmark_phys_t czb;
 647 
 648                         SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
 649                             zb->zb_level - 1,
 650                             zb->zb_blkid * epb + i);
 651                         dsl_scan_visitbp(cbp, &czb, dnp,
 652                             ds, scn, ostype, tx);
 653                 }
 654                 (void) arc_buf_remove_ref(buf, &buf);
 655         } else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) {
 656                 arc_flags_t flags = ARC_FLAG_WAIT;
 657                 dnode_phys_t *cdnp;
 658                 int i, j;
 659                 int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT;
 660                 arc_buf_t *buf;
 661 
 662                 err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, &buf,
 663                     ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
 664                 if (err) {
 665                         scn->scn_phys.scn_errors++;
 666                         return (err);
 667                 }
 668                 for (i = 0, cdnp = buf->b_data; i < epb; i++, cdnp++) {
 669                         for (j = 0; j < cdnp->dn_nblkptr; j++) {
 670                                 blkptr_t *cbp = &cdnp->dn_blkptr[j];
 671                                 dsl_scan_prefetch(scn, buf, cbp,
 672                                     zb->zb_objset, zb->zb_blkid * epb + i, j);
 673                         }
 674                 }
 675                 for (i = 0, cdnp = buf->b_data; i < epb; i++, cdnp++) {
 676                         dsl_scan_visitdnode(scn, ds, ostype,
 677                             cdnp, zb->zb_blkid * epb + i, tx);
 678                 }
 679 
 680                 (void) arc_buf_remove_ref(buf, &buf);
 681         } else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) {
 682                 arc_flags_t flags = ARC_FLAG_WAIT;
 683                 objset_phys_t *osp;
 684                 arc_buf_t *buf;
 685 
 686                 err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, &buf,
 687                     ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
 688                 if (err) {
 689                         scn->scn_phys.scn_errors++;
 690                         return (err);
 691                 }
 692 
 693                 osp = buf->b_data;
 694 
 695                 dsl_scan_visitdnode(scn, ds, osp->os_type,
 696                     &osp->os_meta_dnode, DMU_META_DNODE_OBJECT, tx);
 697 
 698                 if (OBJSET_BUF_HAS_USERUSED(buf)) {
 699                         /*
 700                          * We also always visit user/group accounting
 701                          * objects, and never skip them, even if we are
 702                          * pausing.  This is necessary so that the space
 703                          * deltas from this txg get integrated.
 704                          */
 705                         dsl_scan_visitdnode(scn, ds, osp->os_type,
 706                             &osp->os_groupused_dnode,
 707                             DMU_GROUPUSED_OBJECT, tx);
 708                         dsl_scan_visitdnode(scn, ds, osp->os_type,
 709                             &osp->os_userused_dnode,
 710                             DMU_USERUSED_OBJECT, tx);
 711                 }
 712                 (void) arc_buf_remove_ref(buf, &buf);
 713         }
 714 
 715         return (0);
 716 }
 717 
 718 static void
 719 dsl_scan_visitdnode(dsl_scan_t *scn, dsl_dataset_t *ds,
 720     dmu_objset_type_t ostype, dnode_phys_t *dnp,
 721     uint64_t object, dmu_tx_t *tx)
 722 {
 723         int j;
 724 
 725         for (j = 0; j < dnp->dn_nblkptr; j++) {
 726                 zbookmark_phys_t czb;
 727 
 728                 SET_BOOKMARK(&czb, ds ? ds->ds_object : 0, object,
 729                     dnp->dn_nlevels - 1, j);
 730                 dsl_scan_visitbp(&dnp->dn_blkptr[j],
 731                     &czb, dnp, ds, scn, ostype, tx);
 732         }
 733 
 734         if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
 735                 zbookmark_phys_t czb;
 736                 SET_BOOKMARK(&czb, ds ? ds->ds_object : 0, object,
 737                     0, DMU_SPILL_BLKID);
 738                 dsl_scan_visitbp(&dnp->dn_spill,
 739                     &czb, dnp, ds, scn, ostype, tx);
 740         }
 741 }
 742 
 743 /*
 744  * The arguments are in this order because mdb can only print the
 745  * first 5; we want them to be useful.
 746  */
 747 static void
 748 dsl_scan_visitbp(blkptr_t *bp, const zbookmark_phys_t *zb,
 749     dnode_phys_t *dnp, dsl_dataset_t *ds, dsl_scan_t *scn,
 750     dmu_objset_type_t ostype, dmu_tx_t *tx)
 751 {
 752         dsl_pool_t *dp = scn->scn_dp;
 753         arc_buf_t *buf = NULL;
 754         blkptr_t bp_toread = *bp;
 755 
 756         /* ASSERT(pbuf == NULL || arc_released(pbuf)); */
 757 
 758         if (dsl_scan_check_pause(scn, zb))
 759                 return;
 760 
 761         if (dsl_scan_check_resume(scn, dnp, zb))
 762                 return;
 763 
 764         if (BP_IS_HOLE(bp))
 765                 return;
 766 
 767         scn->scn_visited_this_txg++;
 768 
 769         dprintf_bp(bp,
 770             "visiting ds=%p/%llu zb=%llx/%llx/%llx/%llx bp=%p",
 771             ds, ds ? ds->ds_object : 0,
 772             zb->zb_objset, zb->zb_object, zb->zb_level, zb->zb_blkid,
 773             bp);
 774 
 775         if (bp->blk_birth <= scn->scn_phys.scn_cur_min_txg)
 776                 return;
 777 
 778         if (dsl_scan_recurse(scn, ds, ostype, dnp, &bp_toread, zb, tx) != 0)
 779                 return;
 780 
 781         /*
 782          * If dsl_scan_ddt() has aready visited this block, it will have
 783          * already done any translations or scrubbing, so don't call the
 784          * callback again.
 785          */
 786         if (ddt_class_contains(dp->dp_spa,
 787             scn->scn_phys.scn_ddt_class_max, bp)) {
 788                 ASSERT(buf == NULL);
 789                 return;
 790         }
 791 
 792         /*
 793          * If this block is from the future (after cur_max_txg), then we
 794          * are doing this on behalf of a deleted snapshot, and we will
 795          * revisit the future block on the next pass of this dataset.
 796          * Don't scan it now unless we need to because something
 797          * under it was modified.
 798          */
 799         if (BP_PHYSICAL_BIRTH(bp) <= scn->scn_phys.scn_cur_max_txg) {
 800                 scan_funcs[scn->scn_phys.scn_func](dp, bp, zb);
 801         }
 802 }
 803 
 804 static void
 805 dsl_scan_visit_rootbp(dsl_scan_t *scn, dsl_dataset_t *ds, blkptr_t *bp,
 806     dmu_tx_t *tx)
 807 {
 808         zbookmark_phys_t zb;
 809 
 810         SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
 811             ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
 812         dsl_scan_visitbp(bp, &zb, NULL,
 813             ds, scn, DMU_OST_NONE, tx);
 814 
 815         dprintf_ds(ds, "finished scan%s", "");
 816 }
 817 
 818 void
 819 dsl_scan_ds_destroyed(dsl_dataset_t *ds, dmu_tx_t *tx)
 820 {
 821         dsl_pool_t *dp = ds->ds_dir->dd_pool;
 822         dsl_scan_t *scn = dp->dp_scan;
 823         uint64_t mintxg;
 824 
 825         if (scn->scn_phys.scn_state != DSS_SCANNING)
 826                 return;
 827 
 828         if (scn->scn_phys.scn_bookmark.zb_objset == ds->ds_object) {
 829                 if (ds->ds_is_snapshot) {
 830                         /*
 831                          * Note:
 832                          *  - scn_cur_{min,max}_txg stays the same.
 833                          *  - Setting the flag is not really necessary if
 834                          *    scn_cur_max_txg == scn_max_txg, because there
 835                          *    is nothing after this snapshot that we care
 836                          *    about.  However, we set it anyway and then
 837                          *    ignore it when we retraverse it in
 838                          *    dsl_scan_visitds().
 839                          */
 840                         scn->scn_phys.scn_bookmark.zb_objset =
 841                             dsl_dataset_phys(ds)->ds_next_snap_obj;
 842                         zfs_dbgmsg("destroying ds %llu; currently traversing; "
 843                             "reset zb_objset to %llu",
 844                             (u_longlong_t)ds->ds_object,
 845                             (u_longlong_t)dsl_dataset_phys(ds)->
 846                             ds_next_snap_obj);
 847                         scn->scn_phys.scn_flags |= DSF_VISIT_DS_AGAIN;
 848                 } else {
 849                         SET_BOOKMARK(&scn->scn_phys.scn_bookmark,
 850                             ZB_DESTROYED_OBJSET, 0, 0, 0);
 851                         zfs_dbgmsg("destroying ds %llu; currently traversing; "
 852                             "reset bookmark to -1,0,0,0",
 853                             (u_longlong_t)ds->ds_object);
 854                 }
 855         } else if (zap_lookup_int_key(dp->dp_meta_objset,
 856             scn->scn_phys.scn_queue_obj, ds->ds_object, &mintxg) == 0) {
 857                 ASSERT3U(dsl_dataset_phys(ds)->ds_num_children, <=, 1);
 858                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 859                     scn->scn_phys.scn_queue_obj, ds->ds_object, tx));
 860                 if (ds->ds_is_snapshot) {
 861                         /*
 862                          * We keep the same mintxg; it could be >
 863                          * ds_creation_txg if the previous snapshot was
 864                          * deleted too.
 865                          */
 866                         VERIFY(zap_add_int_key(dp->dp_meta_objset,
 867                             scn->scn_phys.scn_queue_obj,
 868                             dsl_dataset_phys(ds)->ds_next_snap_obj,
 869                             mintxg, tx) == 0);
 870                         zfs_dbgmsg("destroying ds %llu; in queue; "
 871                             "replacing with %llu",
 872                             (u_longlong_t)ds->ds_object,
 873                             (u_longlong_t)dsl_dataset_phys(ds)->
 874                             ds_next_snap_obj);
 875                 } else {
 876                         zfs_dbgmsg("destroying ds %llu; in queue; removing",
 877                             (u_longlong_t)ds->ds_object);
 878                 }
 879         }
 880 
 881         /*
 882          * dsl_scan_sync() should be called after this, and should sync
 883          * out our changed state, but just to be safe, do it here.
 884          */
 885         dsl_scan_sync_state(scn, tx);
 886 }
 887 
 888 void
 889 dsl_scan_ds_snapshotted(dsl_dataset_t *ds, dmu_tx_t *tx)
 890 {
 891         dsl_pool_t *dp = ds->ds_dir->dd_pool;
 892         dsl_scan_t *scn = dp->dp_scan;
 893         uint64_t mintxg;
 894 
 895         if (scn->scn_phys.scn_state != DSS_SCANNING)
 896                 return;
 897 
 898         ASSERT(dsl_dataset_phys(ds)->ds_prev_snap_obj != 0);
 899 
 900         if (scn->scn_phys.scn_bookmark.zb_objset == ds->ds_object) {
 901                 scn->scn_phys.scn_bookmark.zb_objset =
 902                     dsl_dataset_phys(ds)->ds_prev_snap_obj;
 903                 zfs_dbgmsg("snapshotting ds %llu; currently traversing; "
 904                     "reset zb_objset to %llu",
 905                     (u_longlong_t)ds->ds_object,
 906                     (u_longlong_t)dsl_dataset_phys(ds)->ds_prev_snap_obj);
 907         } else if (zap_lookup_int_key(dp->dp_meta_objset,
 908             scn->scn_phys.scn_queue_obj, ds->ds_object, &mintxg) == 0) {
 909                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 910                     scn->scn_phys.scn_queue_obj, ds->ds_object, tx));
 911                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
 912                     scn->scn_phys.scn_queue_obj,
 913                     dsl_dataset_phys(ds)->ds_prev_snap_obj, mintxg, tx) == 0);
 914                 zfs_dbgmsg("snapshotting ds %llu; in queue; "
 915                     "replacing with %llu",
 916                     (u_longlong_t)ds->ds_object,
 917                     (u_longlong_t)dsl_dataset_phys(ds)->ds_prev_snap_obj);
 918         }
 919         dsl_scan_sync_state(scn, tx);
 920 }
 921 
 922 void
 923 dsl_scan_ds_clone_swapped(dsl_dataset_t *ds1, dsl_dataset_t *ds2, dmu_tx_t *tx)
 924 {
 925         dsl_pool_t *dp = ds1->ds_dir->dd_pool;
 926         dsl_scan_t *scn = dp->dp_scan;
 927         uint64_t mintxg;
 928 
 929         if (scn->scn_phys.scn_state != DSS_SCANNING)
 930                 return;
 931 
 932         if (scn->scn_phys.scn_bookmark.zb_objset == ds1->ds_object) {
 933                 scn->scn_phys.scn_bookmark.zb_objset = ds2->ds_object;
 934                 zfs_dbgmsg("clone_swap ds %llu; currently traversing; "
 935                     "reset zb_objset to %llu",
 936                     (u_longlong_t)ds1->ds_object,
 937                     (u_longlong_t)ds2->ds_object);
 938         } else if (scn->scn_phys.scn_bookmark.zb_objset == ds2->ds_object) {
 939                 scn->scn_phys.scn_bookmark.zb_objset = ds1->ds_object;
 940                 zfs_dbgmsg("clone_swap ds %llu; currently traversing; "
 941                     "reset zb_objset to %llu",
 942                     (u_longlong_t)ds2->ds_object,
 943                     (u_longlong_t)ds1->ds_object);
 944         }
 945 
 946         if (zap_lookup_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
 947             ds1->ds_object, &mintxg) == 0) {
 948                 int err;
 949 
 950                 ASSERT3U(mintxg, ==, dsl_dataset_phys(ds1)->ds_prev_snap_txg);
 951                 ASSERT3U(mintxg, ==, dsl_dataset_phys(ds2)->ds_prev_snap_txg);
 952                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 953                     scn->scn_phys.scn_queue_obj, ds1->ds_object, tx));
 954                 err = zap_add_int_key(dp->dp_meta_objset,
 955                     scn->scn_phys.scn_queue_obj, ds2->ds_object, mintxg, tx);
 956                 VERIFY(err == 0 || err == EEXIST);
 957                 if (err == EEXIST) {
 958                         /* Both were there to begin with */
 959                         VERIFY(0 == zap_add_int_key(dp->dp_meta_objset,
 960                             scn->scn_phys.scn_queue_obj,
 961                             ds1->ds_object, mintxg, tx));
 962                 }
 963                 zfs_dbgmsg("clone_swap ds %llu; in queue; "
 964                     "replacing with %llu",
 965                     (u_longlong_t)ds1->ds_object,
 966                     (u_longlong_t)ds2->ds_object);
 967         } else if (zap_lookup_int_key(dp->dp_meta_objset,
 968             scn->scn_phys.scn_queue_obj, ds2->ds_object, &mintxg) == 0) {
 969                 ASSERT3U(mintxg, ==, dsl_dataset_phys(ds1)->ds_prev_snap_txg);
 970                 ASSERT3U(mintxg, ==, dsl_dataset_phys(ds2)->ds_prev_snap_txg);
 971                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 972                     scn->scn_phys.scn_queue_obj, ds2->ds_object, tx));
 973                 VERIFY(0 == zap_add_int_key(dp->dp_meta_objset,
 974                     scn->scn_phys.scn_queue_obj, ds1->ds_object, mintxg, tx));
 975                 zfs_dbgmsg("clone_swap ds %llu; in queue; "
 976                     "replacing with %llu",
 977                     (u_longlong_t)ds2->ds_object,
 978                     (u_longlong_t)ds1->ds_object);
 979         }
 980 
 981         dsl_scan_sync_state(scn, tx);
 982 }
 983 
 984 struct enqueue_clones_arg {
 985         dmu_tx_t *tx;
 986         uint64_t originobj;
 987 };
 988 
 989 /* ARGSUSED */
 990 static int
 991 enqueue_clones_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg)
 992 {
 993         struct enqueue_clones_arg *eca = arg;
 994         dsl_dataset_t *ds;
 995         int err;
 996         dsl_scan_t *scn = dp->dp_scan;
 997 
 998         if (dsl_dir_phys(hds->ds_dir)->dd_origin_obj != eca->originobj)
 999                 return (0);
1000 
1001         err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds);
1002         if (err)
1003                 return (err);
1004 
1005         while (dsl_dataset_phys(ds)->ds_prev_snap_obj != eca->originobj) {
1006                 dsl_dataset_t *prev;
1007                 err = dsl_dataset_hold_obj(dp,
1008                     dsl_dataset_phys(ds)->ds_prev_snap_obj, FTAG, &prev);
1009 
1010                 dsl_dataset_rele(ds, FTAG);
1011                 if (err)
1012                         return (err);
1013                 ds = prev;
1014         }
1015         VERIFY(zap_add_int_key(dp->dp_meta_objset,
1016             scn->scn_phys.scn_queue_obj, ds->ds_object,
1017             dsl_dataset_phys(ds)->ds_prev_snap_txg, eca->tx) == 0);
1018         dsl_dataset_rele(ds, FTAG);
1019         return (0);
1020 }
1021 
1022 static void
1023 dsl_scan_visitds(dsl_scan_t *scn, uint64_t dsobj, dmu_tx_t *tx)
1024 {
1025         dsl_pool_t *dp = scn->scn_dp;
1026         dsl_dataset_t *ds;
1027         objset_t *os;
1028 
1029         VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
1030 
1031         if (scn->scn_phys.scn_cur_min_txg >=
1032             scn->scn_phys.scn_max_txg) {
1033                 /*
1034                  * This can happen if this snapshot was created after the
1035                  * scan started, and we already completed a previous snapshot
1036                  * that was created after the scan started.  This snapshot
1037                  * only references blocks with:
1038                  *
1039                  *      birth < our ds_creation_txg
1040                  *      cur_min_txg is no less than ds_creation_txg.
1041                  *      We have already visited these blocks.
1042                  * or
1043                  *      birth > scn_max_txg
1044                  *      The scan requested not to visit these blocks.
1045                  *
1046                  * Subsequent snapshots (and clones) can reference our
1047                  * blocks, or blocks with even higher birth times.
1048                  * Therefore we do not need to visit them either,
1049                  * so we do not add them to the work queue.
1050                  *
1051                  * Note that checking for cur_min_txg >= cur_max_txg
1052                  * is not sufficient, because in that case we may need to
1053                  * visit subsequent snapshots.  This happens when min_txg > 0,
1054                  * which raises cur_min_txg.  In this case we will visit
1055                  * this dataset but skip all of its blocks, because the
1056                  * rootbp's birth time is < cur_min_txg.  Then we will
1057                  * add the next snapshots/clones to the work queue.
1058                  */
1059                 char *dsname = kmem_alloc(MAXNAMELEN, KM_SLEEP);
1060                 dsl_dataset_name(ds, dsname);
1061                 zfs_dbgmsg("scanning dataset %llu (%s) is unnecessary because "
1062                     "cur_min_txg (%llu) >= max_txg (%llu)",
1063                     dsobj, dsname,
1064                     scn->scn_phys.scn_cur_min_txg,
1065                     scn->scn_phys.scn_max_txg);
1066                 kmem_free(dsname, MAXNAMELEN);
1067 
1068                 goto out;
1069         }
1070 
1071         if (dmu_objset_from_ds(ds, &os))
1072                 goto out;
1073 
1074         /*
1075          * Only the ZIL in the head (non-snapshot) is valid.  Even though
1076          * snapshots can have ZIL block pointers (which may be the same
1077          * BP as in the head), they must be ignored.  So we traverse the
1078          * ZIL here, rather than in scan_recurse(), because the regular
1079          * snapshot block-sharing rules don't apply to it.
1080          */
1081         if (DSL_SCAN_IS_SCRUB_RESILVER(scn) && !ds->ds_is_snapshot)
1082                 dsl_scan_zil(dp, &os->os_zil_header);
1083 
1084         /*
1085          * Iterate over the bps in this ds.
1086          */
1087         dmu_buf_will_dirty(ds->ds_dbuf, tx);
1088         dsl_scan_visit_rootbp(scn, ds, &dsl_dataset_phys(ds)->ds_bp, tx);
1089 
1090         char *dsname = kmem_alloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP);
1091         dsl_dataset_name(ds, dsname);
1092         zfs_dbgmsg("scanned dataset %llu (%s) with min=%llu max=%llu; "
1093             "pausing=%u",
1094             (longlong_t)dsobj, dsname,
1095             (longlong_t)scn->scn_phys.scn_cur_min_txg,
1096             (longlong_t)scn->scn_phys.scn_cur_max_txg,
1097             (int)scn->scn_pausing);
1098         kmem_free(dsname, ZFS_MAX_DATASET_NAME_LEN);
1099 
1100         if (scn->scn_pausing)
1101                 goto out;
1102 
1103         /*
1104          * We've finished this pass over this dataset.
1105          */
1106 
1107         /*
1108          * If we did not completely visit this dataset, do another pass.
1109          */
1110         if (scn->scn_phys.scn_flags & DSF_VISIT_DS_AGAIN) {
1111                 zfs_dbgmsg("incomplete pass; visiting again");
1112                 scn->scn_phys.scn_flags &= ~DSF_VISIT_DS_AGAIN;
1113                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
1114                     scn->scn_phys.scn_queue_obj, ds->ds_object,
1115                     scn->scn_phys.scn_cur_max_txg, tx) == 0);
1116                 goto out;
1117         }
1118 
1119         /*
1120          * Add descendent datasets to work queue.
1121          */
1122         if (dsl_dataset_phys(ds)->ds_next_snap_obj != 0) {
1123                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
1124                     scn->scn_phys.scn_queue_obj,
1125                     dsl_dataset_phys(ds)->ds_next_snap_obj,
1126                     dsl_dataset_phys(ds)->ds_creation_txg, tx) == 0);
1127         }
1128         if (dsl_dataset_phys(ds)->ds_num_children > 1) {
1129                 boolean_t usenext = B_FALSE;
1130                 if (dsl_dataset_phys(ds)->ds_next_clones_obj != 0) {
1131                         uint64_t count;
1132                         /*
1133                          * A bug in a previous version of the code could
1134                          * cause upgrade_clones_cb() to not set
1135                          * ds_next_snap_obj when it should, leading to a
1136                          * missing entry.  Therefore we can only use the
1137                          * next_clones_obj when its count is correct.
1138                          */
1139                         int err = zap_count(dp->dp_meta_objset,
1140                             dsl_dataset_phys(ds)->ds_next_clones_obj, &count);
1141                         if (err == 0 &&
1142                             count == dsl_dataset_phys(ds)->ds_num_children - 1)
1143                                 usenext = B_TRUE;
1144                 }
1145 
1146                 if (usenext) {
1147                         VERIFY0(zap_join_key(dp->dp_meta_objset,
1148                             dsl_dataset_phys(ds)->ds_next_clones_obj,
1149                             scn->scn_phys.scn_queue_obj,
1150                             dsl_dataset_phys(ds)->ds_creation_txg, tx));
1151                 } else {
1152                         struct enqueue_clones_arg eca;
1153                         eca.tx = tx;
1154                         eca.originobj = ds->ds_object;
1155 
1156                         VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
1157                             enqueue_clones_cb, &eca, DS_FIND_CHILDREN));
1158                 }
1159         }
1160 
1161 out:
1162         dsl_dataset_rele(ds, FTAG);
1163 }
1164 
1165 /* ARGSUSED */
1166 static int
1167 enqueue_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg)
1168 {
1169         dmu_tx_t *tx = arg;
1170         dsl_dataset_t *ds;
1171         int err;
1172         dsl_scan_t *scn = dp->dp_scan;
1173 
1174         err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds);
1175         if (err)
1176                 return (err);
1177 
1178         while (dsl_dataset_phys(ds)->ds_prev_snap_obj != 0) {
1179                 dsl_dataset_t *prev;
1180                 err = dsl_dataset_hold_obj(dp,
1181                     dsl_dataset_phys(ds)->ds_prev_snap_obj, FTAG, &prev);
1182                 if (err) {
1183                         dsl_dataset_rele(ds, FTAG);
1184                         return (err);
1185                 }
1186 
1187                 /*
1188                  * If this is a clone, we don't need to worry about it for now.
1189                  */
1190                 if (dsl_dataset_phys(prev)->ds_next_snap_obj != ds->ds_object) {
1191                         dsl_dataset_rele(ds, FTAG);
1192                         dsl_dataset_rele(prev, FTAG);
1193                         return (0);
1194                 }
1195                 dsl_dataset_rele(ds, FTAG);
1196                 ds = prev;
1197         }
1198 
1199         VERIFY(zap_add_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
1200             ds->ds_object, dsl_dataset_phys(ds)->ds_prev_snap_txg, tx) == 0);
1201         dsl_dataset_rele(ds, FTAG);
1202         return (0);
1203 }
1204 
1205 /*
1206  * Scrub/dedup interaction.
1207  *
1208  * If there are N references to a deduped block, we don't want to scrub it
1209  * N times -- ideally, we should scrub it exactly once.
1210  *
1211  * We leverage the fact that the dde's replication class (enum ddt_class)
1212  * is ordered from highest replication class (DDT_CLASS_DITTO) to lowest
1213  * (DDT_CLASS_UNIQUE) so that we may walk the DDT in that order.
1214  *
1215  * To prevent excess scrubbing, the scrub begins by walking the DDT
1216  * to find all blocks with refcnt > 1, and scrubs each of these once.
1217  * Since there are two replication classes which contain blocks with
1218  * refcnt > 1, we scrub the highest replication class (DDT_CLASS_DITTO) first.
1219  * Finally the top-down scrub begins, only visiting blocks with refcnt == 1.
1220  *
1221  * There would be nothing more to say if a block's refcnt couldn't change
1222  * during a scrub, but of course it can so we must account for changes
1223  * in a block's replication class.
1224  *
1225  * Here's an example of what can occur:
1226  *
1227  * If a block has refcnt > 1 during the DDT scrub phase, but has refcnt == 1
1228  * when visited during the top-down scrub phase, it will be scrubbed twice.
1229  * This negates our scrub optimization, but is otherwise harmless.
1230  *
1231  * If a block has refcnt == 1 during the DDT scrub phase, but has refcnt > 1
1232  * on each visit during the top-down scrub phase, it will never be scrubbed.
1233  * To catch this, ddt_sync_entry() notifies the scrub code whenever a block's
1234  * reference class transitions to a higher level (i.e DDT_CLASS_UNIQUE to
1235  * DDT_CLASS_DUPLICATE); if it transitions from refcnt == 1 to refcnt > 1
1236  * while a scrub is in progress, it scrubs the block right then.
1237  */
1238 static void
1239 dsl_scan_ddt(dsl_scan_t *scn, dmu_tx_t *tx)
1240 {
1241         ddt_bookmark_t *ddb = &scn->scn_phys.scn_ddt_bookmark;
1242         ddt_entry_t dde = { 0 };
1243         int error;
1244         uint64_t n = 0;
1245 
1246         while ((error = ddt_walk(scn->scn_dp->dp_spa, ddb, &dde)) == 0) {
1247                 ddt_t *ddt;
1248 
1249                 if (ddb->ddb_class > scn->scn_phys.scn_ddt_class_max)
1250                         break;
1251                 dprintf("visiting ddb=%llu/%llu/%llu/%llx\n",
1252                     (longlong_t)ddb->ddb_class,
1253                     (longlong_t)ddb->ddb_type,
1254                     (longlong_t)ddb->ddb_checksum,
1255                     (longlong_t)ddb->ddb_cursor);
1256 
1257                 /* There should be no pending changes to the dedup table */
1258                 ddt = scn->scn_dp->dp_spa->spa_ddt[ddb->ddb_checksum];
1259                 ASSERT(avl_first(&ddt->ddt_tree) == NULL);
1260 
1261                 dsl_scan_ddt_entry(scn, ddb->ddb_checksum, &dde, tx);
1262                 n++;
1263 
1264                 if (dsl_scan_check_pause(scn, NULL))
1265                         break;
1266         }
1267 
1268         zfs_dbgmsg("scanned %llu ddt entries with class_max = %u; pausing=%u",
1269             (longlong_t)n, (int)scn->scn_phys.scn_ddt_class_max,
1270             (int)scn->scn_pausing);
1271 
1272         ASSERT(error == 0 || error == ENOENT);
1273         ASSERT(error != ENOENT ||
1274             ddb->ddb_class > scn->scn_phys.scn_ddt_class_max);
1275 }
1276 
1277 /* ARGSUSED */
1278 void
1279 dsl_scan_ddt_entry(dsl_scan_t *scn, enum zio_checksum checksum,
1280     ddt_entry_t *dde, dmu_tx_t *tx)
1281 {
1282         const ddt_key_t *ddk = &dde->dde_key;
1283         ddt_phys_t *ddp = dde->dde_phys;
1284         blkptr_t bp;
1285         zbookmark_phys_t zb = { 0 };
1286 
1287         if (scn->scn_phys.scn_state != DSS_SCANNING)
1288                 return;
1289 
1290         for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
1291                 if (ddp->ddp_phys_birth == 0 ||
1292                     ddp->ddp_phys_birth > scn->scn_phys.scn_max_txg)
1293                         continue;
1294                 ddt_bp_create(checksum, ddk, ddp, &bp);
1295 
1296                 scn->scn_visited_this_txg++;
1297                 scan_funcs[scn->scn_phys.scn_func](scn->scn_dp, &bp, &zb);
1298         }
1299 }
1300 
1301 static void
1302 dsl_scan_visit(dsl_scan_t *scn, dmu_tx_t *tx)
1303 {
1304         dsl_pool_t *dp = scn->scn_dp;
1305         zap_cursor_t zc;
1306         zap_attribute_t za;
1307 
1308         if (scn->scn_phys.scn_ddt_bookmark.ddb_class <=
1309             scn->scn_phys.scn_ddt_class_max) {
1310                 scn->scn_phys.scn_cur_min_txg = scn->scn_phys.scn_min_txg;
1311                 scn->scn_phys.scn_cur_max_txg = scn->scn_phys.scn_max_txg;
1312                 dsl_scan_ddt(scn, tx);
1313                 if (scn->scn_pausing)
1314                         return;
1315         }
1316 
1317         if (scn->scn_phys.scn_bookmark.zb_objset == DMU_META_OBJSET) {
1318                 /* First do the MOS & ORIGIN */
1319 
1320                 scn->scn_phys.scn_cur_min_txg = scn->scn_phys.scn_min_txg;
1321                 scn->scn_phys.scn_cur_max_txg = scn->scn_phys.scn_max_txg;
1322                 dsl_scan_visit_rootbp(scn, NULL,
1323                     &dp->dp_meta_rootbp, tx);
1324                 spa_set_rootblkptr(dp->dp_spa, &dp->dp_meta_rootbp);
1325                 if (scn->scn_pausing)
1326                         return;
1327 
1328                 if (spa_version(dp->dp_spa) < SPA_VERSION_DSL_SCRUB) {
1329                         VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
1330                             enqueue_cb, tx, DS_FIND_CHILDREN));
1331                 } else {
1332                         dsl_scan_visitds(scn,
1333                             dp->dp_origin_snap->ds_object, tx);
1334                 }
1335                 ASSERT(!scn->scn_pausing);
1336         } else if (scn->scn_phys.scn_bookmark.zb_objset !=
1337             ZB_DESTROYED_OBJSET) {
1338                 /*
1339                  * If we were paused, continue from here.  Note if the
1340                  * ds we were paused on was deleted, the zb_objset may
1341                  * be -1, so we will skip this and find a new objset
1342                  * below.
1343                  */
1344                 dsl_scan_visitds(scn, scn->scn_phys.scn_bookmark.zb_objset, tx);
1345                 if (scn->scn_pausing)
1346                         return;
1347         }
1348 
1349         /*
1350          * In case we were paused right at the end of the ds, zero the
1351          * bookmark so we don't think that we're still trying to resume.
1352          */
1353         bzero(&scn->scn_phys.scn_bookmark, sizeof (zbookmark_phys_t));
1354 
1355         /* keep pulling things out of the zap-object-as-queue */
1356         while (zap_cursor_init(&zc, dp->dp_meta_objset,
1357             scn->scn_phys.scn_queue_obj),
1358             zap_cursor_retrieve(&zc, &za) == 0) {
1359                 dsl_dataset_t *ds;
1360                 uint64_t dsobj;
1361 
1362                 dsobj = strtonum(za.za_name, NULL);
1363                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
1364                     scn->scn_phys.scn_queue_obj, dsobj, tx));
1365 
1366                 /* Set up min/max txg */
1367                 VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
1368                 if (za.za_first_integer != 0) {
1369                         scn->scn_phys.scn_cur_min_txg =
1370                             MAX(scn->scn_phys.scn_min_txg,
1371                             za.za_first_integer);
1372                 } else {
1373                         scn->scn_phys.scn_cur_min_txg =
1374                             MAX(scn->scn_phys.scn_min_txg,
1375                             dsl_dataset_phys(ds)->ds_prev_snap_txg);
1376                 }
1377                 scn->scn_phys.scn_cur_max_txg = dsl_scan_ds_maxtxg(ds);
1378                 dsl_dataset_rele(ds, FTAG);
1379 
1380                 dsl_scan_visitds(scn, dsobj, tx);
1381                 zap_cursor_fini(&zc);
1382                 if (scn->scn_pausing)
1383                         return;
1384         }
1385         zap_cursor_fini(&zc);
1386 }
1387 
1388 static boolean_t
1389 dsl_scan_free_should_pause(dsl_scan_t *scn)
1390 {
1391         uint64_t elapsed_nanosecs;
1392 
1393         if (zfs_recover)
1394                 return (B_FALSE);
1395 
1396         if (scn->scn_visited_this_txg >= zfs_free_max_blocks)
1397                 return (B_TRUE);
1398 
1399         elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
1400         return (elapsed_nanosecs / NANOSEC > zfs_txg_timeout ||
1401             (NSEC2MSEC(elapsed_nanosecs) > zfs_free_min_time_ms &&
1402             txg_sync_waiting(scn->scn_dp)) ||
1403             spa_shutting_down(scn->scn_dp->dp_spa));
1404 }
1405 
1406 static int
1407 dsl_scan_free_block_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
1408 {
1409         dsl_scan_t *scn = arg;
1410 
1411         if (!scn->scn_is_bptree ||
1412             (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_OBJSET)) {
1413                 if (dsl_scan_free_should_pause(scn))
1414                         return (SET_ERROR(ERESTART));
1415         }
1416 
1417         zio_nowait(zio_free_sync(scn->scn_zio_root, scn->scn_dp->dp_spa,
1418             dmu_tx_get_txg(tx), bp, 0));
1419         dsl_dir_diduse_space(tx->tx_pool->dp_free_dir, DD_USED_HEAD,
1420             -bp_get_dsize_sync(scn->scn_dp->dp_spa, bp),
1421             -BP_GET_PSIZE(bp), -BP_GET_UCSIZE(bp), tx);
1422         scn->scn_visited_this_txg++;
1423         return (0);
1424 }
1425 
1426 boolean_t
1427 dsl_scan_active(dsl_scan_t *scn)
1428 {
1429         spa_t *spa = scn->scn_dp->dp_spa;
1430         uint64_t used = 0, comp, uncomp;
1431 
1432         if (spa->spa_load_state != SPA_LOAD_NONE)
1433                 return (B_FALSE);
1434         if (spa_shutting_down(spa))
1435                 return (B_FALSE);
1436         if (scn->scn_phys.scn_state == DSS_SCANNING ||
1437             (scn->scn_async_destroying && !scn->scn_async_stalled))
1438                 return (B_TRUE);
1439 
1440         if (spa_version(scn->scn_dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
1441                 (void) bpobj_space(&scn->scn_dp->dp_free_bpobj,
1442                     &used, &comp, &uncomp);
1443         }
1444         return (used != 0);
1445 }
1446 
1447 void
1448 dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t *tx)
1449 {
1450         dsl_scan_t *scn = dp->dp_scan;
1451         spa_t *spa = dp->dp_spa;
1452         int err = 0;
1453 
1454         /*
1455          * Check for scn_restart_txg before checking spa_load_state, so
1456          * that we can restart an old-style scan while the pool is being
1457          * imported (see dsl_scan_init).
1458          */
1459         if (dsl_scan_restarting(scn, tx)) {
1460                 pool_scan_func_t func = POOL_SCAN_SCRUB;
1461                 dsl_scan_done(scn, B_FALSE, tx);
1462                 if (vdev_resilver_needed(spa->spa_root_vdev, NULL, NULL))
1463                         func = POOL_SCAN_RESILVER;
1464                 zfs_dbgmsg("restarting scan func=%u txg=%llu",
1465                     func, tx->tx_txg);
1466                 dsl_scan_setup_sync(&func, tx);
1467         }
1468 
1469         /*
1470          * Only process scans in sync pass 1.
1471          */
1472         if (spa_sync_pass(dp->dp_spa) > 1)
1473                 return;
1474 
1475         /*
1476          * If the spa is shutting down, then stop scanning. This will
1477          * ensure that the scan does not dirty any new data during the
1478          * shutdown phase.
1479          */
1480         if (spa_shutting_down(spa))
1481                 return;
1482 
1483         /*
1484          * If the scan is inactive due to a stalled async destroy, try again.
1485          */
1486         if (!scn->scn_async_stalled && !dsl_scan_active(scn))
1487                 return;
1488 
1489         scn->scn_visited_this_txg = 0;
1490         scn->scn_pausing = B_FALSE;
1491         scn->scn_sync_start_time = gethrtime();
1492         spa->spa_scrub_active = B_TRUE;
1493 
1494         /*
1495          * First process the async destroys.  If we pause, don't do
1496          * any scrubbing or resilvering.  This ensures that there are no
1497          * async destroys while we are scanning, so the scan code doesn't
1498          * have to worry about traversing it.  It is also faster to free the
1499          * blocks than to scrub them.
1500          */
1501         if (zfs_free_bpobj_enabled &&
1502             spa_version(dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
1503                 scn->scn_is_bptree = B_FALSE;
1504                 scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
1505                     NULL, ZIO_FLAG_MUSTSUCCEED);
1506                 err = bpobj_iterate(&dp->dp_free_bpobj,
1507                     dsl_scan_free_block_cb, scn, tx);
1508                 VERIFY3U(0, ==, zio_wait(scn->scn_zio_root));
1509 
1510                 if (err != 0 && err != ERESTART)
1511                         zfs_panic_recover("error %u from bpobj_iterate()", err);
1512         }
1513 
1514         if (err == 0 && spa_feature_is_active(spa, SPA_FEATURE_ASYNC_DESTROY)) {
1515                 ASSERT(scn->scn_async_destroying);
1516                 scn->scn_is_bptree = B_TRUE;
1517                 scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
1518                     NULL, ZIO_FLAG_MUSTSUCCEED);
1519                 err = bptree_iterate(dp->dp_meta_objset,
1520                     dp->dp_bptree_obj, B_TRUE, dsl_scan_free_block_cb, scn, tx);
1521                 VERIFY0(zio_wait(scn->scn_zio_root));
1522 
1523                 if (err == EIO || err == ECKSUM) {
1524                         err = 0;
1525                 } else if (err != 0 && err != ERESTART) {
1526                         zfs_panic_recover("error %u from "
1527                             "traverse_dataset_destroyed()", err);
1528                 }
1529 
1530                 if (bptree_is_empty(dp->dp_meta_objset, dp->dp_bptree_obj)) {
1531                         /* finished; deactivate async destroy feature */
1532                         spa_feature_decr(spa, SPA_FEATURE_ASYNC_DESTROY, tx);
1533                         ASSERT(!spa_feature_is_active(spa,
1534                             SPA_FEATURE_ASYNC_DESTROY));
1535                         VERIFY0(zap_remove(dp->dp_meta_objset,
1536                             DMU_POOL_DIRECTORY_OBJECT,
1537                             DMU_POOL_BPTREE_OBJ, tx));
1538                         VERIFY0(bptree_free(dp->dp_meta_objset,
1539                             dp->dp_bptree_obj, tx));
1540                         dp->dp_bptree_obj = 0;
1541                         scn->scn_async_destroying = B_FALSE;
1542                         scn->scn_async_stalled = B_FALSE;
1543                 } else {
1544                         /*
1545                          * If we didn't make progress, mark the async
1546                          * destroy as stalled, so that we will not initiate
1547                          * a spa_sync() on its behalf.  Note that we only
1548                          * check this if we are not finished, because if the
1549                          * bptree had no blocks for us to visit, we can
1550                          * finish without "making progress".
1551                          */
1552                         scn->scn_async_stalled =
1553                             (scn->scn_visited_this_txg == 0);
1554                 }
1555         }
1556         if (scn->scn_visited_this_txg) {
1557                 zfs_dbgmsg("freed %llu blocks in %llums from "
1558                     "free_bpobj/bptree txg %llu; err=%u",
1559                     (longlong_t)scn->scn_visited_this_txg,
1560                     (longlong_t)
1561                     NSEC2MSEC(gethrtime() - scn->scn_sync_start_time),
1562                     (longlong_t)tx->tx_txg, err);
1563                 scn->scn_visited_this_txg = 0;
1564 
1565                 /*
1566                  * Write out changes to the DDT that may be required as a
1567                  * result of the blocks freed.  This ensures that the DDT
1568                  * is clean when a scrub/resilver runs.
1569                  */
1570                 ddt_sync(spa, tx->tx_txg);
1571         }
1572         if (err != 0)
1573                 return;
1574         if (dp->dp_free_dir != NULL && !scn->scn_async_destroying &&
1575             zfs_free_leak_on_eio &&
1576             (dsl_dir_phys(dp->dp_free_dir)->dd_used_bytes != 0 ||
1577             dsl_dir_phys(dp->dp_free_dir)->dd_compressed_bytes != 0 ||
1578             dsl_dir_phys(dp->dp_free_dir)->dd_uncompressed_bytes != 0)) {
1579                 /*
1580                  * We have finished background destroying, but there is still
1581                  * some space left in the dp_free_dir. Transfer this leaked
1582                  * space to the dp_leak_dir.
1583                  */
1584                 if (dp->dp_leak_dir == NULL) {
1585                         rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
1586                         (void) dsl_dir_create_sync(dp, dp->dp_root_dir,
1587                             LEAK_DIR_NAME, tx);
1588                         VERIFY0(dsl_pool_open_special_dir(dp,
1589                             LEAK_DIR_NAME, &dp->dp_leak_dir));
1590                         rrw_exit(&dp->dp_config_rwlock, FTAG);
1591                 }
1592                 dsl_dir_diduse_space(dp->dp_leak_dir, DD_USED_HEAD,
1593                     dsl_dir_phys(dp->dp_free_dir)->dd_used_bytes,
1594                     dsl_dir_phys(dp->dp_free_dir)->dd_compressed_bytes,
1595                     dsl_dir_phys(dp->dp_free_dir)->dd_uncompressed_bytes, tx);
1596                 dsl_dir_diduse_space(dp->dp_free_dir, DD_USED_HEAD,
1597                     -dsl_dir_phys(dp->dp_free_dir)->dd_used_bytes,
1598                     -dsl_dir_phys(dp->dp_free_dir)->dd_compressed_bytes,
1599                     -dsl_dir_phys(dp->dp_free_dir)->dd_uncompressed_bytes, tx);
1600         }
1601         if (dp->dp_free_dir != NULL && !scn->scn_async_destroying) {
1602                 /* finished; verify that space accounting went to zero */
1603                 ASSERT0(dsl_dir_phys(dp->dp_free_dir)->dd_used_bytes);
1604                 ASSERT0(dsl_dir_phys(dp->dp_free_dir)->dd_compressed_bytes);
1605                 ASSERT0(dsl_dir_phys(dp->dp_free_dir)->dd_uncompressed_bytes);
1606         }
1607 
1608         if (scn->scn_phys.scn_state != DSS_SCANNING)
1609                 return;
1610 
1611         if (scn->scn_done_txg == tx->tx_txg) {
1612                 ASSERT(!scn->scn_pausing);
1613                 /* finished with scan. */
1614                 zfs_dbgmsg("txg %llu scan complete", tx->tx_txg);
1615                 dsl_scan_done(scn, B_TRUE, tx);
1616                 ASSERT3U(spa->spa_scrub_inflight, ==, 0);
1617                 dsl_scan_sync_state(scn, tx);
1618                 return;
1619         }
1620 
1621         if (scn->scn_phys.scn_ddt_bookmark.ddb_class <=
1622             scn->scn_phys.scn_ddt_class_max) {
1623                 zfs_dbgmsg("doing scan sync txg %llu; "
1624                     "ddt bm=%llu/%llu/%llu/%llx",
1625                     (longlong_t)tx->tx_txg,
1626                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_class,
1627                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_type,
1628                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_checksum,
1629                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_cursor);
1630                 ASSERT(scn->scn_phys.scn_bookmark.zb_objset == 0);
1631                 ASSERT(scn->scn_phys.scn_bookmark.zb_object == 0);
1632                 ASSERT(scn->scn_phys.scn_bookmark.zb_level == 0);
1633                 ASSERT(scn->scn_phys.scn_bookmark.zb_blkid == 0);
1634         } else {
1635                 zfs_dbgmsg("doing scan sync txg %llu; bm=%llu/%llu/%llu/%llu",
1636                     (longlong_t)tx->tx_txg,
1637                     (longlong_t)scn->scn_phys.scn_bookmark.zb_objset,
1638                     (longlong_t)scn->scn_phys.scn_bookmark.zb_object,
1639                     (longlong_t)scn->scn_phys.scn_bookmark.zb_level,
1640                     (longlong_t)scn->scn_phys.scn_bookmark.zb_blkid);
1641         }
1642 
1643         scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
1644             NULL, ZIO_FLAG_CANFAIL);
1645         dsl_pool_config_enter(dp, FTAG);
1646         dsl_scan_visit(scn, tx);
1647         dsl_pool_config_exit(dp, FTAG);
1648         (void) zio_wait(scn->scn_zio_root);
1649         scn->scn_zio_root = NULL;
1650 
1651         zfs_dbgmsg("visited %llu blocks in %llums",
1652             (longlong_t)scn->scn_visited_this_txg,
1653             (longlong_t)NSEC2MSEC(gethrtime() - scn->scn_sync_start_time));
1654 
1655         if (!scn->scn_pausing) {
1656                 scn->scn_done_txg = tx->tx_txg + 1;
1657                 zfs_dbgmsg("txg %llu traversal complete, waiting till txg %llu",
1658                     tx->tx_txg, scn->scn_done_txg);
1659         }
1660 
1661         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
1662                 mutex_enter(&spa->spa_scrub_lock);
1663                 while (spa->spa_scrub_inflight > 0) {
1664                         cv_wait(&spa->spa_scrub_io_cv,
1665                             &spa->spa_scrub_lock);
1666                 }
1667                 mutex_exit(&spa->spa_scrub_lock);
1668         }
1669 
1670         dsl_scan_sync_state(scn, tx);
1671 }
1672 
1673 /*
1674  * This will start a new scan, or restart an existing one.
1675  */
1676 void
1677 dsl_resilver_restart(dsl_pool_t *dp, uint64_t txg)
1678 {
1679         if (txg == 0) {
1680                 dmu_tx_t *tx;
1681                 tx = dmu_tx_create_dd(dp->dp_mos_dir);
1682                 VERIFY(0 == dmu_tx_assign(tx, TXG_WAIT));
1683 
1684                 txg = dmu_tx_get_txg(tx);
1685                 dp->dp_scan->scn_restart_txg = txg;
1686                 dmu_tx_commit(tx);
1687         } else {
1688                 dp->dp_scan->scn_restart_txg = txg;
1689         }
1690         zfs_dbgmsg("restarting resilver txg=%llu", txg);
1691 }
1692 
1693 boolean_t
1694 dsl_scan_resilvering(dsl_pool_t *dp)
1695 {
1696         return (dp->dp_scan->scn_phys.scn_state == DSS_SCANNING &&
1697             dp->dp_scan->scn_phys.scn_func == POOL_SCAN_RESILVER);
1698 }
1699 
1700 /*
1701  * scrub consumers
1702  */
1703 
1704 static void
1705 count_block(zfs_all_blkstats_t *zab, const blkptr_t *bp)
1706 {
1707         int i;
1708 
1709         /*
1710          * If we resume after a reboot, zab will be NULL; don't record
1711          * incomplete stats in that case.
1712          */
1713         if (zab == NULL)
1714                 return;
1715 
1716         for (i = 0; i < 4; i++) {
1717                 int l = (i < 2) ? BP_GET_LEVEL(bp) : DN_MAX_LEVELS;
1718                 int t = (i & 1) ? BP_GET_TYPE(bp) : DMU_OT_TOTAL;
1719                 if (t & DMU_OT_NEWTYPE)
1720                         t = DMU_OT_OTHER;
1721                 zfs_blkstat_t *zb = &zab->zab_type[l][t];
1722                 int equal;
1723 
1724                 zb->zb_count++;
1725                 zb->zb_asize += BP_GET_ASIZE(bp);
1726                 zb->zb_lsize += BP_GET_LSIZE(bp);
1727                 zb->zb_psize += BP_GET_PSIZE(bp);
1728                 zb->zb_gangs += BP_COUNT_GANG(bp);
1729 
1730                 switch (BP_GET_NDVAS(bp)) {
1731                 case 2:
1732                         if (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1733                             DVA_GET_VDEV(&bp->blk_dva[1]))
1734                                 zb->zb_ditto_2_of_2_samevdev++;
1735                         break;
1736                 case 3:
1737                         equal = (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1738                             DVA_GET_VDEV(&bp->blk_dva[1])) +
1739                             (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1740                             DVA_GET_VDEV(&bp->blk_dva[2])) +
1741                             (DVA_GET_VDEV(&bp->blk_dva[1]) ==
1742                             DVA_GET_VDEV(&bp->blk_dva[2]));
1743                         if (equal == 1)
1744                                 zb->zb_ditto_2_of_3_samevdev++;
1745                         else if (equal == 3)
1746                                 zb->zb_ditto_3_of_3_samevdev++;
1747                         break;
1748                 }
1749         }
1750 }
1751 
1752 static void
1753 dsl_scan_scrub_done(zio_t *zio)
1754 {
1755         spa_t *spa = zio->io_spa;
1756 
1757         zio_data_buf_free(zio->io_data, zio->io_size);
1758 
1759         mutex_enter(&spa->spa_scrub_lock);
1760         spa->spa_scrub_inflight--;
1761         cv_broadcast(&spa->spa_scrub_io_cv);
1762 
1763         if (zio->io_error && (zio->io_error != ECKSUM ||
1764             !(zio->io_flags & ZIO_FLAG_SPECULATIVE))) {
1765                 spa->spa_dsl_pool->dp_scan->scn_phys.scn_errors++;
1766         }
1767         mutex_exit(&spa->spa_scrub_lock);
1768 }
1769 
1770 static int
1771 dsl_scan_scrub_cb(dsl_pool_t *dp,
1772     const blkptr_t *bp, const zbookmark_phys_t *zb)
1773 {
1774         dsl_scan_t *scn = dp->dp_scan;
1775         size_t size = BP_GET_PSIZE(bp);
1776         spa_t *spa = dp->dp_spa;
1777         uint64_t phys_birth = BP_PHYSICAL_BIRTH(bp);
1778         boolean_t needs_io;
1779         int zio_flags = ZIO_FLAG_SCAN_THREAD | ZIO_FLAG_RAW | ZIO_FLAG_CANFAIL;
1780         int scan_delay = 0;
1781 
1782         if (phys_birth <= scn->scn_phys.scn_min_txg ||
1783             phys_birth >= scn->scn_phys.scn_max_txg)
1784                 return (0);
1785 
1786         count_block(dp->dp_blkstats, bp);
1787 
1788         if (BP_IS_EMBEDDED(bp))
1789                 return (0);
1790 
1791         ASSERT(DSL_SCAN_IS_SCRUB_RESILVER(scn));
1792         if (scn->scn_phys.scn_func == POOL_SCAN_SCRUB) {
1793                 zio_flags |= ZIO_FLAG_SCRUB;
1794                 needs_io = B_TRUE;
1795                 scan_delay = zfs_scrub_delay;
1796         } else {
1797                 ASSERT3U(scn->scn_phys.scn_func, ==, POOL_SCAN_RESILVER);
1798                 zio_flags |= ZIO_FLAG_RESILVER;
1799                 needs_io = B_FALSE;
1800                 scan_delay = zfs_resilver_delay;
1801         }
1802 
1803         /* If it's an intent log block, failure is expected. */
1804         if (zb->zb_level == ZB_ZIL_LEVEL)
1805                 zio_flags |= ZIO_FLAG_SPECULATIVE;
1806 
1807         for (int d = 0; d < BP_GET_NDVAS(bp); d++) {
1808                 vdev_t *vd = vdev_lookup_top(spa,
1809                     DVA_GET_VDEV(&bp->blk_dva[d]));
1810 
1811                 /*
1812                  * Keep track of how much data we've examined so that
1813                  * zpool(1M) status can make useful progress reports.
1814                  */
1815                 scn->scn_phys.scn_examined += DVA_GET_ASIZE(&bp->blk_dva[d]);
1816                 spa->spa_scan_pass_exam += DVA_GET_ASIZE(&bp->blk_dva[d]);
1817 
1818                 /* if it's a resilver, this may not be in the target range */
1819                 if (!needs_io) {
1820                         if (DVA_GET_GANG(&bp->blk_dva[d])) {
1821                                 /*
1822                                  * Gang members may be spread across multiple
1823                                  * vdevs, so the best estimate we have is the
1824                                  * scrub range, which has already been checked.
1825                                  * XXX -- it would be better to change our
1826                                  * allocation policy to ensure that all
1827                                  * gang members reside on the same vdev.
1828                                  */
1829                                 needs_io = B_TRUE;
1830                         } else {
1831                                 needs_io = vdev_dtl_contains(vd, DTL_PARTIAL,
1832                                     phys_birth, 1);
1833                         }
1834                 }
1835         }
1836 
1837         if (needs_io && !zfs_no_scrub_io) {
1838                 vdev_t *rvd = spa->spa_root_vdev;
1839                 uint64_t maxinflight = rvd->vdev_children * zfs_top_maxinflight;
1840                 void *data = zio_data_buf_alloc(size);
1841 
1842                 mutex_enter(&spa->spa_scrub_lock);
1843                 while (spa->spa_scrub_inflight >= maxinflight)
1844                         cv_wait(&spa->spa_scrub_io_cv, &spa->spa_scrub_lock);
1845                 spa->spa_scrub_inflight++;
1846                 mutex_exit(&spa->spa_scrub_lock);
1847 
1848                 /*
1849                  * If we're seeing recent (zfs_scan_idle) "important" I/Os
1850                  * then throttle our workload to limit the impact of a scan.
1851                  */
1852                 if (ddi_get_lbolt64() - spa->spa_last_io <= zfs_scan_idle)
1853                         delay(scan_delay);
1854 
1855                 zio_nowait(zio_read(NULL, spa, bp, data, size,
1856                     dsl_scan_scrub_done, NULL, ZIO_PRIORITY_SCRUB,
1857                     zio_flags, zb));
1858         }
1859 
1860         /* do not relocate this block */
1861         return (0);
1862 }
1863 
1864 int
1865 dsl_scan(dsl_pool_t *dp, pool_scan_func_t func)
1866 {
1867         spa_t *spa = dp->dp_spa;
1868 
1869         /*
1870          * Purge all vdev caches and probe all devices.  We do this here
1871          * rather than in sync context because this requires a writer lock
1872          * on the spa_config lock, which we can't do from sync context.  The
1873          * spa_scrub_reopen flag indicates that vdev_open() should not
1874          * attempt to start another scrub.
1875          */
1876         spa_vdev_state_enter(spa, SCL_NONE);
1877         spa->spa_scrub_reopen = B_TRUE;
1878         vdev_reopen(spa->spa_root_vdev);
1879         spa->spa_scrub_reopen = B_FALSE;
1880         (void) spa_vdev_state_exit(spa, NULL, 0);
1881 
1882         return (dsl_sync_task(spa_name(spa), dsl_scan_setup_check,
1883             dsl_scan_setup_sync, &func, 0, ZFS_SPACE_CHECK_NONE));
1884 }
1885 
1886 static boolean_t
1887 dsl_scan_restarting(dsl_scan_t *scn, dmu_tx_t *tx)
1888 {
1889         return (scn->scn_restart_txg != 0 &&
1890             scn->scn_restart_txg <= tx->tx_txg);
1891 }