sys/cddl/contrib/opensolaris/uts/common/fs/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) 2011, 2014 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 *,
  54     const zbookmark_phys_t *);
  55
  56 static scan_cb_t dsl_scan_scrub_cb;
  57 static void dsl_scan_cancel_sync(void *, dmu_tx_t *);
  58 static void dsl_scan_sync_state(dsl_scan_t *, dmu_tx_t *tx);
  59
  60 unsigned int zfs_top_maxinflight = 32;  /* maximum I/Os per top-level */
  61 unsigned int zfs_resilver_delay = 2;    /* number of ticks to delay resilver */
  62 unsigned int zfs_scrub_delay = 4;       /* number of ticks to delay scrub */
  63 unsigned int zfs_scan_idle = 50;        /* idle window in clock ticks */
  64
  65 unsigned int zfs_scan_min_time_ms = 1000; /* min millisecs to scrub per txg */
  66 unsigned int zfs_free_min_time_ms = 1000; /* min millisecs to free per txg */
  67 unsigned int zfs_resilver_min_time_ms = 3000; /* min millisecs to resilver
  68                                                  per txg */
  69 boolean_t zfs_no_scrub_io = B_FALSE; /* set to disable scrub i/o */
  70 boolean_t zfs_no_scrub_prefetch = B_FALSE; /* set to disable scrub prefetch */
  71
  72 SYSCTL_DECL(_vfs_zfs);
  73 SYSCTL_UINT(_vfs_zfs, OID_AUTO, top_maxinflight, CTLFLAG_RWTUN,
  74     &zfs_top_maxinflight, 0, "Maximum I/Os per top-level vdev");
  75 SYSCTL_UINT(_vfs_zfs, OID_AUTO, resilver_delay, CTLFLAG_RWTUN,
  76     &zfs_resilver_delay, 0, "Number of ticks to delay resilver");
  77 SYSCTL_UINT(_vfs_zfs, OID_AUTO, scrub_delay, CTLFLAG_RWTUN,
  78     &zfs_scrub_delay, 0, "Number of ticks to delay scrub");
  79 SYSCTL_UINT(_vfs_zfs, OID_AUTO, scan_idle, CTLFLAG_RWTUN,
  80     &zfs_scan_idle, 0, "Idle scan window in clock ticks");
  81 SYSCTL_UINT(_vfs_zfs, OID_AUTO, scan_min_time_ms, CTLFLAG_RWTUN,
  82     &zfs_scan_min_time_ms, 0, "Min millisecs to scrub per txg");
  83 SYSCTL_UINT(_vfs_zfs, OID_AUTO, free_min_time_ms, CTLFLAG_RWTUN,
  84     &zfs_free_min_time_ms, 0, "Min millisecs to free per txg");
  85 SYSCTL_UINT(_vfs_zfs, OID_AUTO, resilver_min_time_ms, CTLFLAG_RWTUN,
  86     &zfs_resilver_min_time_ms, 0, "Min millisecs to resilver per txg");
  87 SYSCTL_INT(_vfs_zfs, OID_AUTO, no_scrub_io, CTLFLAG_RWTUN,
  88     &zfs_no_scrub_io, 0, "Disable scrub I/O");
  89 SYSCTL_INT(_vfs_zfs, OID_AUTO, no_scrub_prefetch, CTLFLAG_RWTUN,
  90     &zfs_no_scrub_prefetch, 0, "Disable scrub prefetching");
  91
  92 enum ddt_class zfs_scrub_ddt_class_max = DDT_CLASS_DUPLICATE;
  93 /* max number of blocks to free in a single TXG */
  94 uint64_t zfs_free_max_blocks = UINT64_MAX;
  95 SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, free_max_blocks, CTLFLAG_RWTUN,
  96     &zfs_free_max_blocks, 0, "Maximum number of blocks to free in one TXG");
  97
  98
  99 #define DSL_SCAN_IS_SCRUB_RESILVER(scn) \
 100         ((scn)->scn_phys.scn_func == POOL_SCAN_SCRUB || \
 101         (scn)->scn_phys.scn_func == POOL_SCAN_RESILVER)
 102
 103 extern int zfs_txg_timeout;
 104
 105 /* the order has to match pool_scan_type */
 106 static scan_cb_t *scan_funcs[POOL_SCAN_FUNCS] = {
 107         NULL,
 108         dsl_scan_scrub_cb,      /* POOL_SCAN_SCRUB */
 109         dsl_scan_scrub_cb,      /* POOL_SCAN_RESILVER */
 110 };
 111
 112 int
 113 dsl_scan_init(dsl_pool_t *dp, uint64_t txg)
 114 {
 115         int err;
 116         dsl_scan_t *scn;
 117         spa_t *spa = dp->dp_spa;
 118         uint64_t f;
 119
 120         scn = dp->dp_scan = kmem_zalloc(sizeof (dsl_scan_t), KM_SLEEP);
 121         scn->scn_dp = dp;
 122
 123         /*
 124          * It's possible that we're resuming a scan after a reboot so
 125          * make sure that the scan_async_destroying flag is initialized
 126          * appropriately.
 127          */
 128         ASSERT(!scn->scn_async_destroying);
 129         scn->scn_async_destroying = spa_feature_is_active(dp->dp_spa,
 130             SPA_FEATURE_ASYNC_DESTROY);
 131
 132         err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 133             "scrub_func", sizeof (uint64_t), 1, &f);
 134         if (err == 0) {
 135                 /*
 136                  * There was an old-style scrub in progress.  Restart a
 137                  * new-style scrub from the beginning.
 138                  */
 139                 scn->scn_restart_txg = txg;
 140                 zfs_dbgmsg("old-style scrub was in progress; "
 141                     "restarting new-style scrub in txg %llu",
 142                     scn->scn_restart_txg);
 143
 144                 /*
 145                  * Load the queue obj from the old location so that it
 146                  * can be freed by dsl_scan_done().
 147                  */
 148                 (void) zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 149                     "scrub_queue", sizeof (uint64_t), 1,
 150                     &scn->scn_phys.scn_queue_obj);
 151         } else {
 152                 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 153                     DMU_POOL_SCAN, sizeof (uint64_t), SCAN_PHYS_NUMINTS,
 154                     &scn->scn_phys);
 155                 if (err == ENOENT)
 156                         return (0);
 157                 else if (err)
 158                         return (err);
 159
 160                 if (scn->scn_phys.scn_state == DSS_SCANNING &&
 161                     spa_prev_software_version(dp->dp_spa) < SPA_VERSION_SCAN) {
 162                         /*
 163                          * A new-type scrub was in progress on an old
 164                          * pool, and the pool was accessed by old
 165                          * software.  Restart from the beginning, since
 166                          * the old software may have changed the pool in
 167                          * the meantime.
 168                          */
 169                         scn->scn_restart_txg = txg;
 170                         zfs_dbgmsg("new-style scrub was modified "
 171                             "by old software; restarting in txg %llu",
 172                             scn->scn_restart_txg);
 173                 }
 174         }
 175
 176         spa_scan_stat_init(spa);
 177         return (0);
 178 }
 179
 180 void
 181 dsl_scan_fini(dsl_pool_t *dp)
 182 {
 183         if (dp->dp_scan) {
 184                 kmem_free(dp->dp_scan, sizeof (dsl_scan_t));
 185                 dp->dp_scan = NULL;
 186         }
 187 }
 188
 189 /* ARGSUSED */
 190 static int
 191 dsl_scan_setup_check(void *arg, dmu_tx_t *tx)
 192 {
 193         dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan;
 194
 195         if (scn->scn_phys.scn_state == DSS_SCANNING)
 196                 return (SET_ERROR(EBUSY));
 197
 198         return (0);
 199 }
 200
 201 static void
 202 dsl_scan_setup_sync(void *arg, dmu_tx_t *tx)
 203 {
 204         dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan;
 205         pool_scan_func_t *funcp = arg;
 206         dmu_object_type_t ot = 0;
 207         dsl_pool_t *dp = scn->scn_dp;
 208         spa_t *spa = dp->dp_spa;
 209
 210         ASSERT(scn->scn_phys.scn_state != DSS_SCANNING);
 211         ASSERT(*funcp > POOL_SCAN_NONE && *funcp < POOL_SCAN_FUNCS);
 212         bzero(&scn->scn_phys, sizeof (scn->scn_phys));
 213         scn->scn_phys.scn_func = *funcp;
 214         scn->scn_phys.scn_state = DSS_SCANNING;
 215         scn->scn_phys.scn_min_txg = 0;
 216         scn->scn_phys.scn_max_txg = tx->tx_txg;
 217         scn->scn_phys.scn_ddt_class_max = DDT_CLASSES - 1; /* the entire DDT */
 218         scn->scn_phys.scn_start_time = gethrestime_sec();
 219         scn->scn_phys.scn_errors = 0;
 220         scn->scn_phys.scn_to_examine = spa->spa_root_vdev->vdev_stat.vs_alloc;
 221         scn->scn_restart_txg = 0;
 222         scn->scn_done_txg = 0;
 223         spa_scan_stat_init(spa);
 224
 225         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
 226                 scn->scn_phys.scn_ddt_class_max = zfs_scrub_ddt_class_max;
 227
 228                 /* rewrite all disk labels */
 229                 vdev_config_dirty(spa->spa_root_vdev);
 230
 231                 if (vdev_resilver_needed(spa->spa_root_vdev,
 232                     &scn->scn_phys.scn_min_txg, &scn->scn_phys.scn_max_txg)) {
 233                         spa_event_notify(spa, NULL, ESC_ZFS_RESILVER_START);
 234                 } else {
 235                         spa_event_notify(spa, NULL, ESC_ZFS_SCRUB_START);
 236                 }
 237
 238                 spa->spa_scrub_started = B_TRUE;
 239                 /*
 240                  * If this is an incremental scrub, limit the DDT scrub phase
 241                  * to just the auto-ditto class (for correctness); the rest
 242                  * of the scrub should go faster using top-down pruning.
 243                  */
 244                 if (scn->scn_phys.scn_min_txg > TXG_INITIAL)
 245                         scn->scn_phys.scn_ddt_class_max = DDT_CLASS_DITTO;
 246
 247         }
 248
 249         /* back to the generic stuff */
 250
 251         if (dp->dp_blkstats == NULL) {
 252                 dp->dp_blkstats =
 253                     kmem_alloc(sizeof (zfs_all_blkstats_t), KM_SLEEP);
 254         }
 255         bzero(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
 256
 257         if (spa_version(spa) < SPA_VERSION_DSL_SCRUB)
 258                 ot = DMU_OT_ZAP_OTHER;
 259
 260         scn->scn_phys.scn_queue_obj = zap_create(dp->dp_meta_objset,
 261             ot ? ot : DMU_OT_SCAN_QUEUE, DMU_OT_NONE, 0, tx);
 262
 263         dsl_scan_sync_state(scn, tx);
 264
 265         spa_history_log_internal(spa, "scan setup", tx,
 266             "func=%u mintxg=%llu maxtxg=%llu",
 267             *funcp, scn->scn_phys.scn_min_txg, scn->scn_phys.scn_max_txg);
 268 }
 269
 270 /* ARGSUSED */
 271 static void
 272 dsl_scan_done(dsl_scan_t *scn, boolean_t complete, dmu_tx_t *tx)
 273 {
 274         static const char *old_names[] = {
 275                 "scrub_bookmark",
 276                 "scrub_ddt_bookmark",
 277                 "scrub_ddt_class_max",
 278                 "scrub_queue",
 279                 "scrub_min_txg",
 280                 "scrub_max_txg",
 281                 "scrub_func",
 282                 "scrub_errors",
 283                 NULL
 284         };
 285
 286         dsl_pool_t *dp = scn->scn_dp;
 287         spa_t *spa = dp->dp_spa;
 288         int i;
 289
 290         /* Remove any remnants of an old-style scrub. */
 291         for (i = 0; old_names[i]; i++) {
 292                 (void) zap_remove(dp->dp_meta_objset,
 293                     DMU_POOL_DIRECTORY_OBJECT, old_names[i], tx);
 294         }
 295
 296         if (scn->scn_phys.scn_queue_obj != 0) {
 297                 VERIFY(0 == dmu_object_free(dp->dp_meta_objset,
 298                     scn->scn_phys.scn_queue_obj, tx));
 299                 scn->scn_phys.scn_queue_obj = 0;
 300         }
 301
 302         /*
 303          * If we were "restarted" from a stopped state, don't bother
 304          * with anything else.
 305          */
 306         if (scn->scn_phys.scn_state != DSS_SCANNING)
 307                 return;
 308
 309         if (complete)
 310                 scn->scn_phys.scn_state = DSS_FINISHED;
 311         else
 312                 scn->scn_phys.scn_state = DSS_CANCELED;
 313
 314         spa_history_log_internal(spa, "scan done", tx,
 315             "complete=%u", complete);
 316
 317         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
 318                 mutex_enter(&spa->spa_scrub_lock);
 319                 while (spa->spa_scrub_inflight > 0) {
 320                         cv_wait(&spa->spa_scrub_io_cv,
 321                             &spa->spa_scrub_lock);
 322                 }
 323                 mutex_exit(&spa->spa_scrub_lock);
 324                 spa->spa_scrub_started = B_FALSE;
 325                 spa->spa_scrub_active = B_FALSE;
 326
 327                 /*
 328                  * If the scrub/resilver completed, update all DTLs to
 329                  * reflect this.  Whether it succeeded or not, vacate
 330                  * all temporary scrub DTLs.
 331                  */
 332                 vdev_dtl_reassess(spa->spa_root_vdev, tx->tx_txg,
 333                     complete ? scn->scn_phys.scn_max_txg : 0, B_TRUE);
 334                 if (complete) {
 335                         spa_event_notify(spa, NULL, scn->scn_phys.scn_min_txg ?
 336                             ESC_ZFS_RESILVER_FINISH : ESC_ZFS_SCRUB_FINISH);
 337                 }
 338                 spa_errlog_rotate(spa);
 339
 340                 /*
 341                  * We may have finished replacing a device.
 342                  * Let the async thread assess this and handle the detach.
 343                  */
 344                 spa_async_request(spa, SPA_ASYNC_RESILVER_DONE);
 345         }
 346
 347         scn->scn_phys.scn_end_time = gethrestime_sec();
 348 }
 349
 350 /* ARGSUSED */
 351 static int
 352 dsl_scan_cancel_check(void *arg, dmu_tx_t *tx)
 353 {
 354         dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan;
 355
 356         if (scn->scn_phys.scn_state != DSS_SCANNING)
 357                 return (SET_ERROR(ENOENT));
 358         return (0);
 359 }
 360
 361 /* ARGSUSED */
 362 static void
 363 dsl_scan_cancel_sync(void *arg, dmu_tx_t *tx)
 364 {
 365         dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan;
 366
 367         dsl_scan_done(scn, B_FALSE, tx);
 368         dsl_scan_sync_state(scn, tx);
 369 }
 370
 371 int
 372 dsl_scan_cancel(dsl_pool_t *dp)
 373 {
 374         return (dsl_sync_task(spa_name(dp->dp_spa), dsl_scan_cancel_check,
 375             dsl_scan_cancel_sync, NULL, 3, ZFS_SPACE_CHECK_RESERVED));
 376 }
 377
 378 static void dsl_scan_visitbp(blkptr_t *bp,
 379     const zbookmark_phys_t *zb, dnode_phys_t *dnp, arc_buf_t *pbuf,
 380     dsl_dataset_t *ds, dsl_scan_t *scn, dmu_objset_type_t ostype,
 381     dmu_tx_t *tx);
 382 static void dsl_scan_visitdnode(dsl_scan_t *, dsl_dataset_t *ds,
 383     dmu_objset_type_t ostype,
 384     dnode_phys_t *dnp, arc_buf_t *buf, uint64_t object, dmu_tx_t *tx);
 385
 386 void
 387 dsl_free(dsl_pool_t *dp, uint64_t txg, const blkptr_t *bp)
 388 {
 389         zio_free(dp->dp_spa, txg, bp);
 390 }
 391
 392 void
 393 dsl_free_sync(zio_t *pio, dsl_pool_t *dp, uint64_t txg, const blkptr_t *bpp)
 394 {
 395         ASSERT(dsl_pool_sync_context(dp));
 396         zio_nowait(zio_free_sync(pio, dp->dp_spa, txg, bpp, BP_GET_PSIZE(bpp),
 397             pio->io_flags));
 398 }
 399
 400 static uint64_t
 401 dsl_scan_ds_maxtxg(dsl_dataset_t *ds)
 402 {
 403         uint64_t smt = ds->ds_dir->dd_pool->dp_scan->scn_phys.scn_max_txg;
 404         if (dsl_dataset_is_snapshot(ds))
 405                 return (MIN(smt, ds->ds_phys->ds_creation_txg));
 406         return (smt);
 407 }
 408
 409 static void
 410 dsl_scan_sync_state(dsl_scan_t *scn, dmu_tx_t *tx)
 411 {
 412         VERIFY0(zap_update(scn->scn_dp->dp_meta_objset,
 413             DMU_POOL_DIRECTORY_OBJECT,
 414             DMU_POOL_SCAN, sizeof (uint64_t), SCAN_PHYS_NUMINTS,
 415             &scn->scn_phys, tx));
 416 }
 417
 418 static boolean_t
 419 dsl_scan_check_pause(dsl_scan_t *scn, const zbookmark_phys_t *zb)
 420 {
 421         uint64_t elapsed_nanosecs;
 422         unsigned int mintime;
 423
 424         /* we never skip user/group accounting objects */
 425         if (zb && (int64_t)zb->zb_object < 0)
 426                 return (B_FALSE);
 427
 428         if (scn->scn_pausing)
 429                 return (B_TRUE); /* we're already pausing */
 430
 431         if (!ZB_IS_ZERO(&scn->scn_phys.scn_bookmark))
 432                 return (B_FALSE); /* we're resuming */
 433
 434         /* We only know how to resume from level-0 blocks. */
 435         if (zb && zb->zb_level != 0)
 436                 return (B_FALSE);
 437
 438         mintime = (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) ?
 439             zfs_resilver_min_time_ms : zfs_scan_min_time_ms;
 440         elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
 441         if (elapsed_nanosecs / NANOSEC > zfs_txg_timeout ||
 442             (NSEC2MSEC(elapsed_nanosecs) > mintime &&
 443             txg_sync_waiting(scn->scn_dp)) ||
 444             spa_shutting_down(scn->scn_dp->dp_spa)) {
 445                 if (zb) {
 446                         dprintf("pausing at bookmark %llx/%llx/%llx/%llx\n",
 447                             (longlong_t)zb->zb_objset,
 448                             (longlong_t)zb->zb_object,
 449                             (longlong_t)zb->zb_level,
 450                             (longlong_t)zb->zb_blkid);
 451                         scn->scn_phys.scn_bookmark = *zb;
 452                 }
 453                 dprintf("pausing at DDT bookmark %llx/%llx/%llx/%llx\n",
 454                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_class,
 455                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_type,
 456                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_checksum,
 457                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_cursor);
 458                 scn->scn_pausing = B_TRUE;
 459                 return (B_TRUE);
 460         }
 461         return (B_FALSE);
 462 }
 463
 464 typedef struct zil_scan_arg {
 465         dsl_pool_t      *zsa_dp;
 466         zil_header_t    *zsa_zh;
 467 } zil_scan_arg_t;
 468
 469 /* ARGSUSED */
 470 static int
 471 dsl_scan_zil_block(zilog_t *zilog, blkptr_t *bp, void *arg, uint64_t claim_txg)
 472 {
 473         zil_scan_arg_t *zsa = arg;
 474         dsl_pool_t *dp = zsa->zsa_dp;
 475         dsl_scan_t *scn = dp->dp_scan;
 476         zil_header_t *zh = zsa->zsa_zh;
 477         zbookmark_phys_t zb;
 478
 479         if (BP_IS_HOLE(bp) || bp->blk_birth <= scn->scn_phys.scn_cur_min_txg)
 480                 return (0);
 481
 482         /*
 483          * One block ("stubby") can be allocated a long time ago; we
 484          * want to visit that one because it has been allocated
 485          * (on-disk) even if it hasn't been claimed (even though for
 486          * scrub there's nothing to do to it).
 487          */
 488         if (claim_txg == 0 && bp->blk_birth >= spa_first_txg(dp->dp_spa))
 489                 return (0);
 490
 491         SET_BOOKMARK(&zb, zh->zh_log.blk_cksum.zc_word[ZIL_ZC_OBJSET],
 492             ZB_ZIL_OBJECT, ZB_ZIL_LEVEL, bp->blk_cksum.zc_word[ZIL_ZC_SEQ]);
 493
 494         VERIFY(0 == scan_funcs[scn->scn_phys.scn_func](dp, bp, &zb));
 495         return (0);
 496 }
 497
 498 /* ARGSUSED */
 499 static int
 500 dsl_scan_zil_record(zilog_t *zilog, lr_t *lrc, void *arg, uint64_t claim_txg)
 501 {
 502         if (lrc->lrc_txtype == TX_WRITE) {
 503                 zil_scan_arg_t *zsa = arg;
 504                 dsl_pool_t *dp = zsa->zsa_dp;
 505                 dsl_scan_t *scn = dp->dp_scan;
 506                 zil_header_t *zh = zsa->zsa_zh;
 507                 lr_write_t *lr = (lr_write_t *)lrc;
 508                 blkptr_t *bp = &lr->lr_blkptr;
 509                 zbookmark_phys_t zb;
 510
 511                 if (BP_IS_HOLE(bp) ||
 512                     bp->blk_birth <= scn->scn_phys.scn_cur_min_txg)
 513                         return (0);
 514
 515                 /*
 516                  * birth can be < claim_txg if this record's txg is
 517                  * already txg sync'ed (but this log block contains
 518                  * other records that are not synced)
 519                  */
 520                 if (claim_txg == 0 || bp->blk_birth < claim_txg)
 521                         return (0);
 522
 523                 SET_BOOKMARK(&zb, zh->zh_log.blk_cksum.zc_word[ZIL_ZC_OBJSET],
 524                     lr->lr_foid, ZB_ZIL_LEVEL,
 525                     lr->lr_offset / BP_GET_LSIZE(bp));
 526
 527                 VERIFY(0 == scan_funcs[scn->scn_phys.scn_func](dp, bp, &zb));
 528         }
 529         return (0);
 530 }
 531
 532 static void
 533 dsl_scan_zil(dsl_pool_t *dp, zil_header_t *zh)
 534 {
 535         uint64_t claim_txg = zh->zh_claim_txg;
 536         zil_scan_arg_t zsa = { dp, zh };
 537         zilog_t *zilog;
 538
 539         /*
 540          * We only want to visit blocks that have been claimed but not yet
 541          * replayed (or, in read-only mode, blocks that *would* be claimed).
 542          */
 543         if (claim_txg == 0 && spa_writeable(dp->dp_spa))
 544                 return;
 545
 546         zilog = zil_alloc(dp->dp_meta_objset, zh);
 547
 548         (void) zil_parse(zilog, dsl_scan_zil_block, dsl_scan_zil_record, &zsa,
 549             claim_txg);
 550
 551         zil_free(zilog);
 552 }
 553
 554 /* ARGSUSED */
 555 static void
 556 dsl_scan_prefetch(dsl_scan_t *scn, arc_buf_t *buf, blkptr_t *bp,
 557     uint64_t objset, uint64_t object, uint64_t blkid)
 558 {
 559         zbookmark_phys_t czb;
 560         uint32_t flags = ARC_NOWAIT | ARC_PREFETCH;
 561
 562         if (zfs_no_scrub_prefetch)
 563                 return;
 564
 565         if (BP_IS_HOLE(bp) || bp->blk_birth <= scn->scn_phys.scn_min_txg ||
 566             (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_DNODE))
 567                 return;
 568
 569         SET_BOOKMARK(&czb, objset, object, BP_GET_LEVEL(bp), blkid);
 570
 571         (void) arc_read(scn->scn_zio_root, scn->scn_dp->dp_spa, bp,
 572             NULL, NULL, ZIO_PRIORITY_ASYNC_READ,
 573             ZIO_FLAG_CANFAIL | ZIO_FLAG_SCAN_THREAD, &flags, &czb);
 574 }
 575
 576 static boolean_t
 577 dsl_scan_check_resume(dsl_scan_t *scn, const dnode_phys_t *dnp,
 578     const zbookmark_phys_t *zb)
 579 {
 580         /*
 581          * We never skip over user/group accounting objects (obj<0)
 582          */
 583         if (!ZB_IS_ZERO(&scn->scn_phys.scn_bookmark) &&
 584             (int64_t)zb->zb_object >= 0) {
 585                 /*
 586                  * If we already visited this bp & everything below (in
 587                  * a prior txg sync), don't bother doing it again.
 588                  */
 589                 if (zbookmark_is_before(dnp, zb, &scn->scn_phys.scn_bookmark))
 590                         return (B_TRUE);
 591
 592                 /*
 593                  * If we found the block we're trying to resume from, or
 594                  * we went past it to a different object, zero it out to
 595                  * indicate that it's OK to start checking for pausing
 596                  * again.
 597                  */
 598                 if (bcmp(zb, &scn->scn_phys.scn_bookmark, sizeof (*zb)) == 0 ||
 599                     zb->zb_object > scn->scn_phys.scn_bookmark.zb_object) {
 600                         dprintf("resuming at %llx/%llx/%llx/%llx\n",
 601                             (longlong_t)zb->zb_objset,
 602                             (longlong_t)zb->zb_object,
 603                             (longlong_t)zb->zb_level,
 604                             (longlong_t)zb->zb_blkid);
 605                         bzero(&scn->scn_phys.scn_bookmark, sizeof (*zb));
 606                 }
 607         }
 608         return (B_FALSE);
 609 }
 610
 611 /*
 612  * Return nonzero on i/o error.
 613  * Return new buf to write out in *bufp.
 614  */
 615 static int
 616 dsl_scan_recurse(dsl_scan_t *scn, dsl_dataset_t *ds, dmu_objset_type_t ostype,
 617     dnode_phys_t *dnp, const blkptr_t *bp,
 618     const zbookmark_phys_t *zb, dmu_tx_t *tx, arc_buf_t **bufp)
 619 {
 620         dsl_pool_t *dp = scn->scn_dp;
 621         int zio_flags = ZIO_FLAG_CANFAIL | ZIO_FLAG_SCAN_THREAD;
 622         int err;
 623
 624         if (BP_GET_LEVEL(bp) > 0) {
 625                 uint32_t flags = ARC_WAIT;
 626                 int i;
 627                 blkptr_t *cbp;
 628                 int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT;
 629
 630                 err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, bufp,
 631                     ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
 632                 if (err) {
 633                         scn->scn_phys.scn_errors++;
 634                         return (err);
 635                 }
 636                 for (i = 0, cbp = (*bufp)->b_data; i < epb; i++, cbp++) {
 637                         dsl_scan_prefetch(scn, *bufp, cbp, zb->zb_objset,
 638                             zb->zb_object, zb->zb_blkid * epb + i);
 639                 }
 640                 for (i = 0, cbp = (*bufp)->b_data; i < epb; i++, cbp++) {
 641                         zbookmark_phys_t czb;
 642
 643                         SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
 644                             zb->zb_level - 1,
 645                             zb->zb_blkid * epb + i);
 646                         dsl_scan_visitbp(cbp, &czb, dnp,
 647                             *bufp, ds, scn, ostype, tx);
 648                 }
 649         } else if (BP_GET_TYPE(bp) == DMU_OT_USERGROUP_USED) {
 650                 uint32_t flags = ARC_WAIT;
 651
 652                 err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, bufp,
 653                     ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
 654                 if (err) {
 655                         scn->scn_phys.scn_errors++;
 656                         return (err);
 657                 }
 658         } else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) {
 659                 uint32_t flags = ARC_WAIT;
 660                 dnode_phys_t *cdnp;
 661                 int i, j;
 662                 int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT;
 663
 664                 err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, bufp,
 665                     ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
 666                 if (err) {
 667                         scn->scn_phys.scn_errors++;
 668                         return (err);
 669                 }
 670                 for (i = 0, cdnp = (*bufp)->b_data; i < epb; i++, cdnp++) {
 671                         for (j = 0; j < cdnp->dn_nblkptr; j++) {
 672                                 blkptr_t *cbp = &cdnp->dn_blkptr[j];
 673                                 dsl_scan_prefetch(scn, *bufp, cbp,
 674                                     zb->zb_objset, zb->zb_blkid * epb + i, j);
 675                         }
 676                 }
 677                 for (i = 0, cdnp = (*bufp)->b_data; i < epb; i++, cdnp++) {
 678                         dsl_scan_visitdnode(scn, ds, ostype,
 679                             cdnp, *bufp, zb->zb_blkid * epb + i, tx);
 680                 }
 681
 682         } else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) {
 683                 uint32_t flags = ARC_WAIT;
 684                 objset_phys_t *osp;
 685
 686                 err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, bufp,
 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 = (*bufp)->b_data;
 694
 695                 dsl_scan_visitdnode(scn, ds, osp->os_type,
 696                     &osp->os_meta_dnode, *bufp, DMU_META_DNODE_OBJECT, tx);
 697
 698                 if (OBJSET_BUF_HAS_USERUSED(*bufp)) {
 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, *bufp,
 707                             DMU_GROUPUSED_OBJECT, tx);
 708                         dsl_scan_visitdnode(scn, ds, osp->os_type,
 709                             &osp->os_userused_dnode, *bufp,
 710                             DMU_USERUSED_OBJECT, tx);
 711                 }
 712         }
 713
 714         return (0);
 715 }
 716
 717 static void
 718 dsl_scan_visitdnode(dsl_scan_t *scn, dsl_dataset_t *ds,
 719     dmu_objset_type_t ostype, dnode_phys_t *dnp, arc_buf_t *buf,
 720     uint64_t object, dmu_tx_t *tx)
 721 {
 722         int j;
 723
 724         for (j = 0; j < dnp->dn_nblkptr; j++) {
 725                 zbookmark_phys_t czb;
 726
 727                 SET_BOOKMARK(&czb, ds ? ds->ds_object : 0, object,
 728                     dnp->dn_nlevels - 1, j);
 729                 dsl_scan_visitbp(&dnp->dn_blkptr[j],
 730                     &czb, dnp, buf, ds, scn, ostype, tx);
 731         }
 732
 733         if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
 734                 zbookmark_phys_t czb;
 735                 SET_BOOKMARK(&czb, ds ? ds->ds_object : 0, object,
 736                     0, DMU_SPILL_BLKID);
 737                 dsl_scan_visitbp(&dnp->dn_spill,
 738                     &czb, dnp, buf, ds, scn, ostype, tx);
 739         }
 740 }
 741
 742 /*
 743  * The arguments are in this order because mdb can only print the
 744  * first 5; we want them to be useful.
 745  */
 746 static void
 747 dsl_scan_visitbp(blkptr_t *bp, const zbookmark_phys_t *zb,
 748     dnode_phys_t *dnp, arc_buf_t *pbuf,
 749     dsl_dataset_t *ds, dsl_scan_t *scn, dmu_objset_type_t ostype,
 750     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 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         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,
 779             &buf) != 0)
 780                 return;
 781
 782         /*
 783          * If dsl_scan_ddt() has aready visited this block, it will have
 784          * already done any translations or scrubbing, so don't call the
 785          * callback again.
 786          */
 787         if (ddt_class_contains(dp->dp_spa,
 788             scn->scn_phys.scn_ddt_class_max, bp)) {
 789                 ASSERT(buf == NULL);
 790                 return;
 791         }
 792
 793         /*
 794          * If this block is from the future (after cur_max_txg), then we
 795          * are doing this on behalf of a deleted snapshot, and we will
 796          * revisit the future block on the next pass of this dataset.
 797          * Don't scan it now unless we need to because something
 798          * under it was modified.
 799          */
 800         if (BP_PHYSICAL_BIRTH(bp) <= scn->scn_phys.scn_cur_max_txg) {
 801                 scan_funcs[scn->scn_phys.scn_func](dp, bp, zb);
 802         }
 803         if (buf)
 804                 (void) arc_buf_remove_ref(buf, &buf);
 805 }
 806
 807 static void
 808 dsl_scan_visit_rootbp(dsl_scan_t *scn, dsl_dataset_t *ds, blkptr_t *bp,
 809     dmu_tx_t *tx)
 810 {
 811         zbookmark_phys_t zb;
 812
 813         SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
 814             ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
 815         dsl_scan_visitbp(bp, &zb, NULL, NULL,
 816             ds, scn, DMU_OST_NONE, tx);
 817
 818         dprintf_ds(ds, "finished scan%s", "");
 819 }
 820
 821 void
 822 dsl_scan_ds_destroyed(dsl_dataset_t *ds, dmu_tx_t *tx)
 823 {
 824         dsl_pool_t *dp = ds->ds_dir->dd_pool;
 825         dsl_scan_t *scn = dp->dp_scan;
 826         uint64_t mintxg;
 827
 828         if (scn->scn_phys.scn_state != DSS_SCANNING)
 829                 return;
 830
 831         if (scn->scn_phys.scn_bookmark.zb_objset == ds->ds_object) {
 832                 if (dsl_dataset_is_snapshot(ds)) {
 833                         /* Note, scn_cur_{min,max}_txg stays the same. */
 834                         scn->scn_phys.scn_bookmark.zb_objset =
 835                             ds->ds_phys->ds_next_snap_obj;
 836                         zfs_dbgmsg("destroying ds %llu; currently traversing; "
 837                             "reset zb_objset to %llu",
 838                             (u_longlong_t)ds->ds_object,
 839                             (u_longlong_t)ds->ds_phys->ds_next_snap_obj);
 840                         scn->scn_phys.scn_flags |= DSF_VISIT_DS_AGAIN;
 841                 } else {
 842                         SET_BOOKMARK(&scn->scn_phys.scn_bookmark,
 843                             ZB_DESTROYED_OBJSET, 0, 0, 0);
 844                         zfs_dbgmsg("destroying ds %llu; currently traversing; "
 845                             "reset bookmark to -1,0,0,0",
 846                             (u_longlong_t)ds->ds_object);
 847                 }
 848         } else if (zap_lookup_int_key(dp->dp_meta_objset,
 849             scn->scn_phys.scn_queue_obj, ds->ds_object, &mintxg) == 0) {
 850                 ASSERT3U(ds->ds_phys->ds_num_children, <=, 1);
 851                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 852                     scn->scn_phys.scn_queue_obj, ds->ds_object, tx));
 853                 if (dsl_dataset_is_snapshot(ds)) {
 854                         /*
 855                          * We keep the same mintxg; it could be >
 856                          * ds_creation_txg if the previous snapshot was
 857                          * deleted too.
 858                          */
 859                         VERIFY(zap_add_int_key(dp->dp_meta_objset,
 860                             scn->scn_phys.scn_queue_obj,
 861                             ds->ds_phys->ds_next_snap_obj, mintxg, tx) == 0);
 862                         zfs_dbgmsg("destroying ds %llu; in queue; "
 863                             "replacing with %llu",
 864                             (u_longlong_t)ds->ds_object,
 865                             (u_longlong_t)ds->ds_phys->ds_next_snap_obj);
 866                 } else {
 867                         zfs_dbgmsg("destroying ds %llu; in queue; removing",
 868                             (u_longlong_t)ds->ds_object);
 869                 }
 870         } else {
 871                 zfs_dbgmsg("destroying ds %llu; ignoring",
 872                     (u_longlong_t)ds->ds_object);
 873         }
 874
 875         /*
 876          * dsl_scan_sync() should be called after this, and should sync
 877          * out our changed state, but just to be safe, do it here.
 878          */
 879         dsl_scan_sync_state(scn, tx);
 880 }
 881
 882 void
 883 dsl_scan_ds_snapshotted(dsl_dataset_t *ds, dmu_tx_t *tx)
 884 {
 885         dsl_pool_t *dp = ds->ds_dir->dd_pool;
 886         dsl_scan_t *scn = dp->dp_scan;
 887         uint64_t mintxg;
 888
 889         if (scn->scn_phys.scn_state != DSS_SCANNING)
 890                 return;
 891
 892         ASSERT(ds->ds_phys->ds_prev_snap_obj != 0);
 893
 894         if (scn->scn_phys.scn_bookmark.zb_objset == ds->ds_object) {
 895                 scn->scn_phys.scn_bookmark.zb_objset =
 896                     ds->ds_phys->ds_prev_snap_obj;
 897                 zfs_dbgmsg("snapshotting ds %llu; currently traversing; "
 898                     "reset zb_objset to %llu",
 899                     (u_longlong_t)ds->ds_object,
 900                     (u_longlong_t)ds->ds_phys->ds_prev_snap_obj);
 901         } else if (zap_lookup_int_key(dp->dp_meta_objset,
 902             scn->scn_phys.scn_queue_obj, ds->ds_object, &mintxg) == 0) {
 903                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 904                     scn->scn_phys.scn_queue_obj, ds->ds_object, tx));
 905                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
 906                     scn->scn_phys.scn_queue_obj,
 907                     ds->ds_phys->ds_prev_snap_obj, mintxg, tx) == 0);
 908                 zfs_dbgmsg("snapshotting ds %llu; in queue; "
 909                     "replacing with %llu",
 910                     (u_longlong_t)ds->ds_object,
 911                     (u_longlong_t)ds->ds_phys->ds_prev_snap_obj);
 912         }
 913         dsl_scan_sync_state(scn, tx);
 914 }
 915
 916 void
 917 dsl_scan_ds_clone_swapped(dsl_dataset_t *ds1, dsl_dataset_t *ds2, dmu_tx_t *tx)
 918 {
 919         dsl_pool_t *dp = ds1->ds_dir->dd_pool;
 920         dsl_scan_t *scn = dp->dp_scan;
 921         uint64_t mintxg;
 922
 923         if (scn->scn_phys.scn_state != DSS_SCANNING)
 924                 return;
 925
 926         if (scn->scn_phys.scn_bookmark.zb_objset == ds1->ds_object) {
 927                 scn->scn_phys.scn_bookmark.zb_objset = ds2->ds_object;
 928                 zfs_dbgmsg("clone_swap ds %llu; currently traversing; "
 929                     "reset zb_objset to %llu",
 930                     (u_longlong_t)ds1->ds_object,
 931                     (u_longlong_t)ds2->ds_object);
 932         } else if (scn->scn_phys.scn_bookmark.zb_objset == ds2->ds_object) {
 933                 scn->scn_phys.scn_bookmark.zb_objset = ds1->ds_object;
 934                 zfs_dbgmsg("clone_swap ds %llu; currently traversing; "
 935                     "reset zb_objset to %llu",
 936                     (u_longlong_t)ds2->ds_object,
 937                     (u_longlong_t)ds1->ds_object);
 938         }
 939
 940         if (zap_lookup_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
 941             ds1->ds_object, &mintxg) == 0) {
 942                 int err;
 943
 944                 ASSERT3U(mintxg, ==, ds1->ds_phys->ds_prev_snap_txg);
 945                 ASSERT3U(mintxg, ==, ds2->ds_phys->ds_prev_snap_txg);
 946                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 947                     scn->scn_phys.scn_queue_obj, ds1->ds_object, tx));
 948                 err = zap_add_int_key(dp->dp_meta_objset,
 949                     scn->scn_phys.scn_queue_obj, ds2->ds_object, mintxg, tx);
 950                 VERIFY(err == 0 || err == EEXIST);
 951                 if (err == EEXIST) {
 952                         /* Both were there to begin with */
 953                         VERIFY(0 == zap_add_int_key(dp->dp_meta_objset,
 954                             scn->scn_phys.scn_queue_obj,
 955                             ds1->ds_object, mintxg, tx));
 956                 }
 957                 zfs_dbgmsg("clone_swap ds %llu; in queue; "
 958                     "replacing with %llu",
 959                     (u_longlong_t)ds1->ds_object,
 960                     (u_longlong_t)ds2->ds_object);
 961         } else if (zap_lookup_int_key(dp->dp_meta_objset,
 962             scn->scn_phys.scn_queue_obj, ds2->ds_object, &mintxg) == 0) {
 963                 ASSERT3U(mintxg, ==, ds1->ds_phys->ds_prev_snap_txg);
 964                 ASSERT3U(mintxg, ==, ds2->ds_phys->ds_prev_snap_txg);
 965                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 966                     scn->scn_phys.scn_queue_obj, ds2->ds_object, tx));
 967                 VERIFY(0 == zap_add_int_key(dp->dp_meta_objset,
 968                     scn->scn_phys.scn_queue_obj, ds1->ds_object, mintxg, tx));
 969                 zfs_dbgmsg("clone_swap ds %llu; in queue; "
 970                     "replacing with %llu",
 971                     (u_longlong_t)ds2->ds_object,
 972                     (u_longlong_t)ds1->ds_object);
 973         }
 974
 975         dsl_scan_sync_state(scn, tx);
 976 }
 977
 978 struct enqueue_clones_arg {
 979         dmu_tx_t *tx;
 980         uint64_t originobj;
 981 };
 982
 983 /* ARGSUSED */
 984 static int
 985 enqueue_clones_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg)
 986 {
 987         struct enqueue_clones_arg *eca = arg;
 988         dsl_dataset_t *ds;
 989         int err;
 990         dsl_scan_t *scn = dp->dp_scan;
 991
 992         if (hds->ds_dir->dd_phys->dd_origin_obj != eca->originobj)
 993                 return (0);
 994
 995         err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds);
 996         if (err)
 997                 return (err);
 998
 999         while (ds->ds_phys->ds_prev_snap_obj != eca->originobj) {
1000                 dsl_dataset_t *prev;
1001                 err = dsl_dataset_hold_obj(dp,
1002                     ds->ds_phys->ds_prev_snap_obj, FTAG, &prev);
1003
1004                 dsl_dataset_rele(ds, FTAG);
1005                 if (err)
1006                         return (err);
1007                 ds = prev;
1008         }
1009         VERIFY(zap_add_int_key(dp->dp_meta_objset,
1010             scn->scn_phys.scn_queue_obj, ds->ds_object,
1011             ds->ds_phys->ds_prev_snap_txg, eca->tx) == 0);
1012         dsl_dataset_rele(ds, FTAG);
1013         return (0);
1014 }
1015
1016 static void
1017 dsl_scan_visitds(dsl_scan_t *scn, uint64_t dsobj, dmu_tx_t *tx)
1018 {
1019         dsl_pool_t *dp = scn->scn_dp;
1020         dsl_dataset_t *ds;
1021         objset_t *os;
1022
1023         VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
1024
1025         if (dmu_objset_from_ds(ds, &os))
1026                 goto out;
1027
1028         /*
1029          * Only the ZIL in the head (non-snapshot) is valid.  Even though
1030          * snapshots can have ZIL block pointers (which may be the same
1031          * BP as in the head), they must be ignored.  So we traverse the
1032          * ZIL here, rather than in scan_recurse(), because the regular
1033          * snapshot block-sharing rules don't apply to it.
1034          */
1035         if (DSL_SCAN_IS_SCRUB_RESILVER(scn) && !dsl_dataset_is_snapshot(ds))
1036                 dsl_scan_zil(dp, &os->os_zil_header);
1037
1038         /*
1039          * Iterate over the bps in this ds.
1040          */
1041         dmu_buf_will_dirty(ds->ds_dbuf, tx);
1042         dsl_scan_visit_rootbp(scn, ds, &ds->ds_phys->ds_bp, tx);
1043
1044         char *dsname = kmem_alloc(ZFS_MAXNAMELEN, KM_SLEEP);
1045         dsl_dataset_name(ds, dsname);
1046         zfs_dbgmsg("scanned dataset %llu (%s) with min=%llu max=%llu; "
1047             "pausing=%u",
1048             (longlong_t)dsobj, dsname,
1049             (longlong_t)scn->scn_phys.scn_cur_min_txg,
1050             (longlong_t)scn->scn_phys.scn_cur_max_txg,
1051             (int)scn->scn_pausing);
1052         kmem_free(dsname, ZFS_MAXNAMELEN);
1053
1054         if (scn->scn_pausing)
1055                 goto out;
1056
1057         /*
1058          * We've finished this pass over this dataset.
1059          */
1060
1061         /*
1062          * If we did not completely visit this dataset, do another pass.
1063          */
1064         if (scn->scn_phys.scn_flags & DSF_VISIT_DS_AGAIN) {
1065                 zfs_dbgmsg("incomplete pass; visiting again");
1066                 scn->scn_phys.scn_flags &= ~DSF_VISIT_DS_AGAIN;
1067                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
1068                     scn->scn_phys.scn_queue_obj, ds->ds_object,
1069                     scn->scn_phys.scn_cur_max_txg, tx) == 0);
1070                 goto out;
1071         }
1072
1073         /*
1074          * Add descendent datasets to work queue.
1075          */
1076         if (ds->ds_phys->ds_next_snap_obj != 0) {
1077                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
1078                     scn->scn_phys.scn_queue_obj, ds->ds_phys->ds_next_snap_obj,
1079                     ds->ds_phys->ds_creation_txg, tx) == 0);
1080         }
1081         if (ds->ds_phys->ds_num_children > 1) {
1082                 boolean_t usenext = B_FALSE;
1083                 if (ds->ds_phys->ds_next_clones_obj != 0) {
1084                         uint64_t count;
1085                         /*
1086                          * A bug in a previous version of the code could
1087                          * cause upgrade_clones_cb() to not set
1088                          * ds_next_snap_obj when it should, leading to a
1089                          * missing entry.  Therefore we can only use the
1090                          * next_clones_obj when its count is correct.
1091                          */
1092                         int err = zap_count(dp->dp_meta_objset,
1093                             ds->ds_phys->ds_next_clones_obj, &count);
1094                         if (err == 0 &&
1095                             count == ds->ds_phys->ds_num_children - 1)
1096                                 usenext = B_TRUE;
1097                 }
1098
1099                 if (usenext) {
1100                         VERIFY0(zap_join_key(dp->dp_meta_objset,
1101                             ds->ds_phys->ds_next_clones_obj,
1102                             scn->scn_phys.scn_queue_obj,
1103                             ds->ds_phys->ds_creation_txg, tx));
1104                 } else {
1105                         struct enqueue_clones_arg eca;
1106                         eca.tx = tx;
1107                         eca.originobj = ds->ds_object;
1108
1109                         VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
1110                             enqueue_clones_cb, &eca, DS_FIND_CHILDREN));
1111                 }
1112         }
1113
1114 out:
1115         dsl_dataset_rele(ds, FTAG);
1116 }
1117
1118 /* ARGSUSED */
1119 static int
1120 enqueue_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg)
1121 {
1122         dmu_tx_t *tx = arg;
1123         dsl_dataset_t *ds;
1124         int err;
1125         dsl_scan_t *scn = dp->dp_scan;
1126
1127         err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds);
1128         if (err)
1129                 return (err);
1130
1131         while (ds->ds_phys->ds_prev_snap_obj != 0) {
1132                 dsl_dataset_t *prev;
1133                 err = dsl_dataset_hold_obj(dp, ds->ds_phys->ds_prev_snap_obj,
1134                     FTAG, &prev);
1135                 if (err) {
1136                         dsl_dataset_rele(ds, FTAG);
1137                         return (err);
1138                 }
1139
1140                 /*
1141                  * If this is a clone, we don't need to worry about it for now.
1142                  */
1143                 if (prev->ds_phys->ds_next_snap_obj != ds->ds_object) {
1144                         dsl_dataset_rele(ds, FTAG);
1145                         dsl_dataset_rele(prev, FTAG);
1146                         return (0);
1147                 }
1148                 dsl_dataset_rele(ds, FTAG);
1149                 ds = prev;
1150         }
1151
1152         VERIFY(zap_add_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
1153             ds->ds_object, ds->ds_phys->ds_prev_snap_txg, tx) == 0);
1154         dsl_dataset_rele(ds, FTAG);
1155         return (0);
1156 }
1157
1158 /*
1159  * Scrub/dedup interaction.
1160  *
1161  * If there are N references to a deduped block, we don't want to scrub it
1162  * N times -- ideally, we should scrub it exactly once.
1163  *
1164  * We leverage the fact that the dde's replication class (enum ddt_class)
1165  * is ordered from highest replication class (DDT_CLASS_DITTO) to lowest
1166  * (DDT_CLASS_UNIQUE) so that we may walk the DDT in that order.
1167  *
1168  * To prevent excess scrubbing, the scrub begins by walking the DDT
1169  * to find all blocks with refcnt > 1, and scrubs each of these once.
1170  * Since there are two replication classes which contain blocks with
1171  * refcnt > 1, we scrub the highest replication class (DDT_CLASS_DITTO) first.
1172  * Finally the top-down scrub begins, only visiting blocks with refcnt == 1.
1173  *
1174  * There would be nothing more to say if a block's refcnt couldn't change
1175  * during a scrub, but of course it can so we must account for changes
1176  * in a block's replication class.
1177  *
1178  * Here's an example of what can occur:
1179  *
1180  * If a block has refcnt > 1 during the DDT scrub phase, but has refcnt == 1
1181  * when visited during the top-down scrub phase, it will be scrubbed twice.
1182  * This negates our scrub optimization, but is otherwise harmless.
1183  *
1184  * If a block has refcnt == 1 during the DDT scrub phase, but has refcnt > 1
1185  * on each visit during the top-down scrub phase, it will never be scrubbed.
1186  * To catch this, ddt_sync_entry() notifies the scrub code whenever a block's
1187  * reference class transitions to a higher level (i.e DDT_CLASS_UNIQUE to
1188  * DDT_CLASS_DUPLICATE); if it transitions from refcnt == 1 to refcnt > 1
1189  * while a scrub is in progress, it scrubs the block right then.
1190  */
1191 static void
1192 dsl_scan_ddt(dsl_scan_t *scn, dmu_tx_t *tx)
1193 {
1194         ddt_bookmark_t *ddb = &scn->scn_phys.scn_ddt_bookmark;
1195         ddt_entry_t dde = { 0 };
1196         int error;
1197         uint64_t n = 0;
1198
1199         while ((error = ddt_walk(scn->scn_dp->dp_spa, ddb, &dde)) == 0) {
1200                 ddt_t *ddt;
1201
1202                 if (ddb->ddb_class > scn->scn_phys.scn_ddt_class_max)
1203                         break;
1204                 dprintf("visiting ddb=%llu/%llu/%llu/%llx\n",
1205                     (longlong_t)ddb->ddb_class,
1206                     (longlong_t)ddb->ddb_type,
1207                     (longlong_t)ddb->ddb_checksum,
1208                     (longlong_t)ddb->ddb_cursor);
1209
1210                 /* There should be no pending changes to the dedup table */
1211                 ddt = scn->scn_dp->dp_spa->spa_ddt[ddb->ddb_checksum];
1212                 ASSERT(avl_first(&ddt->ddt_tree) == NULL);
1213
1214                 dsl_scan_ddt_entry(scn, ddb->ddb_checksum, &dde, tx);
1215                 n++;
1216
1217                 if (dsl_scan_check_pause(scn, NULL))
1218                         break;
1219         }
1220
1221         zfs_dbgmsg("scanned %llu ddt entries with class_max = %u; pausing=%u",
1222             (longlong_t)n, (int)scn->scn_phys.scn_ddt_class_max,
1223             (int)scn->scn_pausing);
1224
1225         ASSERT(error == 0 || error == ENOENT);
1226         ASSERT(error != ENOENT ||
1227             ddb->ddb_class > scn->scn_phys.scn_ddt_class_max);
1228 }
1229
1230 /* ARGSUSED */
1231 void
1232 dsl_scan_ddt_entry(dsl_scan_t *scn, enum zio_checksum checksum,
1233     ddt_entry_t *dde, dmu_tx_t *tx)
1234 {
1235         const ddt_key_t *ddk = &dde->dde_key;
1236         ddt_phys_t *ddp = dde->dde_phys;
1237         blkptr_t bp;
1238         zbookmark_phys_t zb = { 0 };
1239
1240         if (scn->scn_phys.scn_state != DSS_SCANNING)
1241                 return;
1242
1243         for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
1244                 if (ddp->ddp_phys_birth == 0 ||
1245                     ddp->ddp_phys_birth > scn->scn_phys.scn_max_txg)
1246                         continue;
1247                 ddt_bp_create(checksum, ddk, ddp, &bp);
1248
1249                 scn->scn_visited_this_txg++;
1250                 scan_funcs[scn->scn_phys.scn_func](scn->scn_dp, &bp, &zb);
1251         }
1252 }
1253
1254 static void
1255 dsl_scan_visit(dsl_scan_t *scn, dmu_tx_t *tx)
1256 {
1257         dsl_pool_t *dp = scn->scn_dp;
1258         zap_cursor_t zc;
1259         zap_attribute_t za;
1260
1261         if (scn->scn_phys.scn_ddt_bookmark.ddb_class <=
1262             scn->scn_phys.scn_ddt_class_max) {
1263                 scn->scn_phys.scn_cur_min_txg = scn->scn_phys.scn_min_txg;
1264                 scn->scn_phys.scn_cur_max_txg = scn->scn_phys.scn_max_txg;
1265                 dsl_scan_ddt(scn, tx);
1266                 if (scn->scn_pausing)
1267                         return;
1268         }
1269
1270         if (scn->scn_phys.scn_bookmark.zb_objset == DMU_META_OBJSET) {
1271                 /* First do the MOS & ORIGIN */
1272
1273                 scn->scn_phys.scn_cur_min_txg = scn->scn_phys.scn_min_txg;
1274                 scn->scn_phys.scn_cur_max_txg = scn->scn_phys.scn_max_txg;
1275                 dsl_scan_visit_rootbp(scn, NULL,
1276                     &dp->dp_meta_rootbp, tx);
1277                 spa_set_rootblkptr(dp->dp_spa, &dp->dp_meta_rootbp);
1278                 if (scn->scn_pausing)
1279                         return;
1280
1281                 if (spa_version(dp->dp_spa) < SPA_VERSION_DSL_SCRUB) {
1282                         VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
1283                             enqueue_cb, tx, DS_FIND_CHILDREN));
1284                 } else {
1285                         dsl_scan_visitds(scn,
1286                             dp->dp_origin_snap->ds_object, tx);
1287                 }
1288                 ASSERT(!scn->scn_pausing);
1289         } else if (scn->scn_phys.scn_bookmark.zb_objset !=
1290             ZB_DESTROYED_OBJSET) {
1291                 /*
1292                  * If we were paused, continue from here.  Note if the
1293                  * ds we were paused on was deleted, the zb_objset may
1294                  * be -1, so we will skip this and find a new objset
1295                  * below.
1296                  */
1297                 dsl_scan_visitds(scn, scn->scn_phys.scn_bookmark.zb_objset, tx);
1298                 if (scn->scn_pausing)
1299                         return;
1300         }
1301
1302         /*
1303          * In case we were paused right at the end of the ds, zero the
1304          * bookmark so we don't think that we're still trying to resume.
1305          */
1306         bzero(&scn->scn_phys.scn_bookmark, sizeof (zbookmark_phys_t));
1307
1308         /* keep pulling things out of the zap-object-as-queue */
1309         while (zap_cursor_init(&zc, dp->dp_meta_objset,
1310             scn->scn_phys.scn_queue_obj),
1311             zap_cursor_retrieve(&zc, &za) == 0) {
1312                 dsl_dataset_t *ds;
1313                 uint64_t dsobj;
1314
1315                 dsobj = strtonum(za.za_name, NULL);
1316                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
1317                     scn->scn_phys.scn_queue_obj, dsobj, tx));
1318
1319                 /* Set up min/max txg */
1320                 VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
1321                 if (za.za_first_integer != 0) {
1322                         scn->scn_phys.scn_cur_min_txg =
1323                             MAX(scn->scn_phys.scn_min_txg,
1324                             za.za_first_integer);
1325                 } else {
1326                         scn->scn_phys.scn_cur_min_txg =
1327                             MAX(scn->scn_phys.scn_min_txg,
1328                             ds->ds_phys->ds_prev_snap_txg);
1329                 }
1330                 scn->scn_phys.scn_cur_max_txg = dsl_scan_ds_maxtxg(ds);
1331                 dsl_dataset_rele(ds, FTAG);
1332
1333                 dsl_scan_visitds(scn, dsobj, tx);
1334                 zap_cursor_fini(&zc);
1335                 if (scn->scn_pausing)
1336                         return;
1337         }
1338         zap_cursor_fini(&zc);
1339 }
1340
1341 static boolean_t
1342 dsl_scan_free_should_pause(dsl_scan_t *scn)
1343 {
1344         uint64_t elapsed_nanosecs;
1345
1346         if (zfs_recover)
1347                 return (B_FALSE);
1348
1349         if (scn->scn_visited_this_txg >= zfs_free_max_blocks)
1350                 return (B_TRUE);
1351
1352         elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
1353         return (elapsed_nanosecs / NANOSEC > zfs_txg_timeout ||
1354             (NSEC2MSEC(elapsed_nanosecs) > zfs_free_min_time_ms &&
1355             txg_sync_waiting(scn->scn_dp)) ||
1356             spa_shutting_down(scn->scn_dp->dp_spa));
1357 }
1358
1359 static int
1360 dsl_scan_free_block_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
1361 {
1362         dsl_scan_t *scn = arg;
1363
1364         if (!scn->scn_is_bptree ||
1365             (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_OBJSET)) {
1366                 if (dsl_scan_free_should_pause(scn))
1367                         return (SET_ERROR(ERESTART));
1368         }
1369
1370         zio_nowait(zio_free_sync(scn->scn_zio_root, scn->scn_dp->dp_spa,
1371             dmu_tx_get_txg(tx), bp, BP_GET_PSIZE(bp), 0));
1372         dsl_dir_diduse_space(tx->tx_pool->dp_free_dir, DD_USED_HEAD,
1373             -bp_get_dsize_sync(scn->scn_dp->dp_spa, bp),
1374             -BP_GET_PSIZE(bp), -BP_GET_UCSIZE(bp), tx);
1375         scn->scn_visited_this_txg++;
1376         return (0);
1377 }
1378
1379 boolean_t
1380 dsl_scan_active(dsl_scan_t *scn)
1381 {
1382         spa_t *spa = scn->scn_dp->dp_spa;
1383         uint64_t used = 0, comp, uncomp;
1384
1385         if (spa->spa_load_state != SPA_LOAD_NONE)
1386                 return (B_FALSE);
1387         if (spa_shutting_down(spa))
1388                 return (B_FALSE);
1389         if (scn->scn_phys.scn_state == DSS_SCANNING ||
1390             (scn->scn_async_destroying && !scn->scn_async_stalled))
1391                 return (B_TRUE);
1392
1393         if (spa_version(scn->scn_dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
1394                 (void) bpobj_space(&scn->scn_dp->dp_free_bpobj,
1395                     &used, &comp, &uncomp);
1396         }
1397         return (used != 0);
1398 }
1399
1400 void
1401 dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t *tx)
1402 {
1403         dsl_scan_t *scn = dp->dp_scan;
1404         spa_t *spa = dp->dp_spa;
1405         int err = 0;
1406
1407         /*
1408          * Check for scn_restart_txg before checking spa_load_state, so
1409          * that we can restart an old-style scan while the pool is being
1410          * imported (see dsl_scan_init).
1411          */
1412         if (scn->scn_restart_txg != 0 &&
1413             scn->scn_restart_txg <= tx->tx_txg) {
1414                 pool_scan_func_t func = POOL_SCAN_SCRUB;
1415                 dsl_scan_done(scn, B_FALSE, tx);
1416                 if (vdev_resilver_needed(spa->spa_root_vdev, NULL, NULL))
1417                         func = POOL_SCAN_RESILVER;
1418                 zfs_dbgmsg("restarting scan func=%u txg=%llu",
1419                     func, tx->tx_txg);
1420                 dsl_scan_setup_sync(&func, tx);
1421         }
1422
1423         /*
1424          * If the scan is inactive due to a stalled async destroy, try again.
1425          */
1426         if ((!scn->scn_async_stalled && !dsl_scan_active(scn)) ||
1427             spa_sync_pass(dp->dp_spa) > 1)
1428                 return;
1429
1430         scn->scn_visited_this_txg = 0;
1431         scn->scn_pausing = B_FALSE;
1432         scn->scn_sync_start_time = gethrtime();
1433         spa->spa_scrub_active = B_TRUE;
1434
1435         /*
1436          * First process the async destroys.  If we pause, don't do
1437          * any scrubbing or resilvering.  This ensures that there are no
1438          * async destroys while we are scanning, so the scan code doesn't
1439          * have to worry about traversing it.  It is also faster to free the
1440          * blocks than to scrub them.
1441          */
1442         if (spa_version(dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
1443                 scn->scn_is_bptree = B_FALSE;
1444                 scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
1445                     NULL, ZIO_FLAG_MUSTSUCCEED);
1446                 err = bpobj_iterate(&dp->dp_free_bpobj,
1447                     dsl_scan_free_block_cb, scn, tx);
1448                 VERIFY3U(0, ==, zio_wait(scn->scn_zio_root));
1449
1450                 if (err != 0 && err != ERESTART)
1451                         zfs_panic_recover("error %u from bpobj_iterate()", err);
1452         }
1453
1454         if (err == 0 && spa_feature_is_active(spa, SPA_FEATURE_ASYNC_DESTROY)) {
1455                 ASSERT(scn->scn_async_destroying);
1456                 scn->scn_is_bptree = B_TRUE;
1457                 scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
1458                     NULL, ZIO_FLAG_MUSTSUCCEED);
1459                 err = bptree_iterate(dp->dp_meta_objset,
1460                     dp->dp_bptree_obj, B_TRUE, dsl_scan_free_block_cb, scn, tx);
1461                 VERIFY0(zio_wait(scn->scn_zio_root));
1462
1463                 if (err == EIO || err == ECKSUM) {
1464                         err = 0;
1465                 } else if (err != 0 && err != ERESTART) {
1466                         zfs_panic_recover("error %u from "
1467                             "traverse_dataset_destroyed()", err);
1468                 }
1469
1470                 /*
1471                  * If we didn't make progress, mark the async destroy as
1472                  * stalled, so that we will not initiate a spa_sync() on
1473                  * its behalf.
1474                  */
1475                 scn->scn_async_stalled = (scn->scn_visited_this_txg == 0);
1476
1477                 if (bptree_is_empty(dp->dp_meta_objset, dp->dp_bptree_obj)) {
1478                         /* finished; deactivate async destroy feature */
1479                         spa_feature_decr(spa, SPA_FEATURE_ASYNC_DESTROY, tx);
1480                         ASSERT(!spa_feature_is_active(spa,
1481                             SPA_FEATURE_ASYNC_DESTROY));
1482                         VERIFY0(zap_remove(dp->dp_meta_objset,
1483                             DMU_POOL_DIRECTORY_OBJECT,
1484                             DMU_POOL_BPTREE_OBJ, tx));
1485                         VERIFY0(bptree_free(dp->dp_meta_objset,
1486                             dp->dp_bptree_obj, tx));
1487                         dp->dp_bptree_obj = 0;
1488                         scn->scn_async_destroying = B_FALSE;
1489                 }
1490         }
1491         if (scn->scn_visited_this_txg) {
1492                 zfs_dbgmsg("freed %llu blocks in %llums from "
1493                     "free_bpobj/bptree txg %llu; err=%u",
1494                     (longlong_t)scn->scn_visited_this_txg,
1495                     (longlong_t)
1496                     NSEC2MSEC(gethrtime() - scn->scn_sync_start_time),
1497                     (longlong_t)tx->tx_txg, err);
1498                 scn->scn_visited_this_txg = 0;
1499
1500                 /*
1501                  * Write out changes to the DDT that may be required as a
1502                  * result of the blocks freed.  This ensures that the DDT
1503                  * is clean when a scrub/resilver runs.
1504                  */
1505                 ddt_sync(spa, tx->tx_txg);
1506         }
1507         if (err != 0)
1508                 return;
1509         if (!scn->scn_async_destroying && zfs_free_leak_on_eio &&
1510             (dp->dp_free_dir->dd_phys->dd_used_bytes != 0 ||
1511             dp->dp_free_dir->dd_phys->dd_compressed_bytes != 0 ||
1512             dp->dp_free_dir->dd_phys->dd_uncompressed_bytes != 0)) {
1513                 /*
1514                  * We have finished background destroying, but there is still
1515                  * some space left in the dp_free_dir. Transfer this leaked
1516                  * space to the dp_leak_dir.
1517                  */
1518                 if (dp->dp_leak_dir == NULL) {
1519                         rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
1520                         (void) dsl_dir_create_sync(dp, dp->dp_root_dir,
1521                             LEAK_DIR_NAME, tx);
1522                         VERIFY0(dsl_pool_open_special_dir(dp,
1523                             LEAK_DIR_NAME, &dp->dp_leak_dir));
1524                         rrw_exit(&dp->dp_config_rwlock, FTAG);
1525                 }
1526                 dsl_dir_diduse_space(dp->dp_leak_dir, DD_USED_HEAD,
1527                     dp->dp_free_dir->dd_phys->dd_used_bytes,
1528                     dp->dp_free_dir->dd_phys->dd_compressed_bytes,
1529                     dp->dp_free_dir->dd_phys->dd_uncompressed_bytes, tx);
1530                 dsl_dir_diduse_space(dp->dp_free_dir, DD_USED_HEAD,
1531                     -dp->dp_free_dir->dd_phys->dd_used_bytes,
1532                     -dp->dp_free_dir->dd_phys->dd_compressed_bytes,
1533                     -dp->dp_free_dir->dd_phys->dd_uncompressed_bytes, tx);
1534         }
1535         if (!scn->scn_async_destroying) {
1536                 /* finished; verify that space accounting went to zero */
1537                 ASSERT0(dp->dp_free_dir->dd_phys->dd_used_bytes);
1538                 ASSERT0(dp->dp_free_dir->dd_phys->dd_compressed_bytes);
1539                 ASSERT0(dp->dp_free_dir->dd_phys->dd_uncompressed_bytes);
1540         }
1541
1542         if (scn->scn_phys.scn_state != DSS_SCANNING)
1543                 return;
1544
1545         if (scn->scn_done_txg == tx->tx_txg) {
1546                 ASSERT(!scn->scn_pausing);
1547                 /* finished with scan. */
1548                 zfs_dbgmsg("txg %llu scan complete", tx->tx_txg);
1549                 dsl_scan_done(scn, B_TRUE, tx);
1550                 ASSERT3U(spa->spa_scrub_inflight, ==, 0);
1551                 dsl_scan_sync_state(scn, tx);
1552                 return;
1553         }
1554
1555         if (scn->scn_phys.scn_ddt_bookmark.ddb_class <=
1556             scn->scn_phys.scn_ddt_class_max) {
1557                 zfs_dbgmsg("doing scan sync txg %llu; "
1558                     "ddt bm=%llu/%llu/%llu/%llx",
1559                     (longlong_t)tx->tx_txg,
1560                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_class,
1561                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_type,
1562                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_checksum,
1563                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_cursor);
1564                 ASSERT(scn->scn_phys.scn_bookmark.zb_objset == 0);
1565                 ASSERT(scn->scn_phys.scn_bookmark.zb_object == 0);
1566                 ASSERT(scn->scn_phys.scn_bookmark.zb_level == 0);
1567                 ASSERT(scn->scn_phys.scn_bookmark.zb_blkid == 0);
1568         } else {
1569                 zfs_dbgmsg("doing scan sync txg %llu; bm=%llu/%llu/%llu/%llu",
1570                     (longlong_t)tx->tx_txg,
1571                     (longlong_t)scn->scn_phys.scn_bookmark.zb_objset,
1572                     (longlong_t)scn->scn_phys.scn_bookmark.zb_object,
1573                     (longlong_t)scn->scn_phys.scn_bookmark.zb_level,
1574                     (longlong_t)scn->scn_phys.scn_bookmark.zb_blkid);
1575         }
1576
1577         scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
1578             NULL, ZIO_FLAG_CANFAIL);
1579         dsl_pool_config_enter(dp, FTAG);
1580         dsl_scan_visit(scn, tx);
1581         dsl_pool_config_exit(dp, FTAG);
1582         (void) zio_wait(scn->scn_zio_root);
1583         scn->scn_zio_root = NULL;
1584
1585         zfs_dbgmsg("visited %llu blocks in %llums",
1586             (longlong_t)scn->scn_visited_this_txg,
1587             (longlong_t)NSEC2MSEC(gethrtime() - scn->scn_sync_start_time));
1588
1589         if (!scn->scn_pausing) {
1590                 scn->scn_done_txg = tx->tx_txg + 1;
1591                 zfs_dbgmsg("txg %llu traversal complete, waiting till txg %llu",
1592                     tx->tx_txg, scn->scn_done_txg);
1593         }
1594
1595         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
1596                 mutex_enter(&spa->spa_scrub_lock);
1597                 while (spa->spa_scrub_inflight > 0) {
1598                         cv_wait(&spa->spa_scrub_io_cv,
1599                             &spa->spa_scrub_lock);
1600                 }
1601                 mutex_exit(&spa->spa_scrub_lock);
1602         }
1603
1604         dsl_scan_sync_state(scn, tx);
1605 }
1606
1607 /*
1608  * This will start a new scan, or restart an existing one.
1609  */
1610 void
1611 dsl_resilver_restart(dsl_pool_t *dp, uint64_t txg)
1612 {
1613         if (txg == 0) {
1614                 dmu_tx_t *tx;
1615                 tx = dmu_tx_create_dd(dp->dp_mos_dir);
1616                 VERIFY(0 == dmu_tx_assign(tx, TXG_WAIT));
1617
1618                 txg = dmu_tx_get_txg(tx);
1619                 dp->dp_scan->scn_restart_txg = txg;
1620                 dmu_tx_commit(tx);
1621         } else {
1622                 dp->dp_scan->scn_restart_txg = txg;
1623         }
1624         zfs_dbgmsg("restarting resilver txg=%llu", txg);
1625 }
1626
1627 boolean_t
1628 dsl_scan_resilvering(dsl_pool_t *dp)
1629 {
1630         return (dp->dp_scan->scn_phys.scn_state == DSS_SCANNING &&
1631             dp->dp_scan->scn_phys.scn_func == POOL_SCAN_RESILVER);
1632 }
1633
1634 /*
1635  * scrub consumers
1636  */
1637
1638 static void
1639 count_block(zfs_all_blkstats_t *zab, const blkptr_t *bp)
1640 {
1641         int i;
1642
1643         /*
1644          * If we resume after a reboot, zab will be NULL; don't record
1645          * incomplete stats in that case.
1646          */
1647         if (zab == NULL)
1648                 return;
1649
1650         for (i = 0; i < 4; i++) {
1651                 int l = (i < 2) ? BP_GET_LEVEL(bp) : DN_MAX_LEVELS;
1652                 int t = (i & 1) ? BP_GET_TYPE(bp) : DMU_OT_TOTAL;
1653                 if (t & DMU_OT_NEWTYPE)
1654                         t = DMU_OT_OTHER;
1655                 zfs_blkstat_t *zb = &zab->zab_type[l][t];
1656                 int equal;
1657
1658                 zb->zb_count++;
1659                 zb->zb_asize += BP_GET_ASIZE(bp);
1660                 zb->zb_lsize += BP_GET_LSIZE(bp);
1661                 zb->zb_psize += BP_GET_PSIZE(bp);
1662                 zb->zb_gangs += BP_COUNT_GANG(bp);
1663
1664                 switch (BP_GET_NDVAS(bp)) {
1665                 case 2:
1666                         if (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1667                             DVA_GET_VDEV(&bp->blk_dva[1]))
1668                                 zb->zb_ditto_2_of_2_samevdev++;
1669                         break;
1670                 case 3:
1671                         equal = (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1672                             DVA_GET_VDEV(&bp->blk_dva[1])) +
1673                             (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1674                             DVA_GET_VDEV(&bp->blk_dva[2])) +
1675                             (DVA_GET_VDEV(&bp->blk_dva[1]) ==
1676                             DVA_GET_VDEV(&bp->blk_dva[2]));
1677                         if (equal == 1)
1678                                 zb->zb_ditto_2_of_3_samevdev++;
1679                         else if (equal == 3)
1680                                 zb->zb_ditto_3_of_3_samevdev++;
1681                         break;
1682                 }
1683         }
1684 }
1685
1686 static void
1687 dsl_scan_scrub_done(zio_t *zio)
1688 {
1689         spa_t *spa = zio->io_spa;
1690
1691         zio_data_buf_free(zio->io_data, zio->io_size);
1692
1693         mutex_enter(&spa->spa_scrub_lock);
1694         spa->spa_scrub_inflight--;
1695         cv_broadcast(&spa->spa_scrub_io_cv);
1696
1697         if (zio->io_error && (zio->io_error != ECKSUM ||
1698             !(zio->io_flags & ZIO_FLAG_SPECULATIVE))) {
1699                 spa->spa_dsl_pool->dp_scan->scn_phys.scn_errors++;
1700         }
1701         mutex_exit(&spa->spa_scrub_lock);
1702 }
1703
1704 static int
1705 dsl_scan_scrub_cb(dsl_pool_t *dp,
1706     const blkptr_t *bp, const zbookmark_phys_t *zb)
1707 {
1708         dsl_scan_t *scn = dp->dp_scan;
1709         size_t size = BP_GET_PSIZE(bp);
1710         spa_t *spa = dp->dp_spa;
1711         uint64_t phys_birth = BP_PHYSICAL_BIRTH(bp);
1712         boolean_t needs_io;
1713         int zio_flags = ZIO_FLAG_SCAN_THREAD | ZIO_FLAG_RAW | ZIO_FLAG_CANFAIL;
1714         unsigned int scan_delay = 0;
1715
1716         if (phys_birth <= scn->scn_phys.scn_min_txg ||
1717             phys_birth >= scn->scn_phys.scn_max_txg)
1718                 return (0);
1719
1720         count_block(dp->dp_blkstats, bp);
1721
1722         if (BP_IS_EMBEDDED(bp))
1723                 return (0);
1724
1725         ASSERT(DSL_SCAN_IS_SCRUB_RESILVER(scn));
1726         if (scn->scn_phys.scn_func == POOL_SCAN_SCRUB) {
1727                 zio_flags |= ZIO_FLAG_SCRUB;
1728                 needs_io = B_TRUE;
1729                 scan_delay = zfs_scrub_delay;
1730         } else {
1731                 ASSERT3U(scn->scn_phys.scn_func, ==, POOL_SCAN_RESILVER);
1732                 zio_flags |= ZIO_FLAG_RESILVER;
1733                 needs_io = B_FALSE;
1734                 scan_delay = zfs_resilver_delay;
1735         }
1736
1737         /* If it's an intent log block, failure is expected. */
1738         if (zb->zb_level == ZB_ZIL_LEVEL)
1739                 zio_flags |= ZIO_FLAG_SPECULATIVE;
1740
1741         for (int d = 0; d < BP_GET_NDVAS(bp); d++) {
1742                 vdev_t *vd = vdev_lookup_top(spa,
1743                     DVA_GET_VDEV(&bp->blk_dva[d]));
1744
1745                 /*
1746                  * Keep track of how much data we've examined so that
1747                  * zpool(1M) status can make useful progress reports.
1748                  */
1749                 scn->scn_phys.scn_examined += DVA_GET_ASIZE(&bp->blk_dva[d]);
1750                 spa->spa_scan_pass_exam += DVA_GET_ASIZE(&bp->blk_dva[d]);
1751
1752                 /* if it's a resilver, this may not be in the target range */
1753                 if (!needs_io) {
1754                         if (DVA_GET_GANG(&bp->blk_dva[d])) {
1755                                 /*
1756                                  * Gang members may be spread across multiple
1757                                  * vdevs, so the best estimate we have is the
1758                                  * scrub range, which has already been checked.
1759                                  * XXX -- it would be better to change our
1760                                  * allocation policy to ensure that all
1761                                  * gang members reside on the same vdev.
1762                                  */
1763                                 needs_io = B_TRUE;
1764                         } else {
1765                                 needs_io = vdev_dtl_contains(vd, DTL_PARTIAL,
1766                                     phys_birth, 1);
1767                         }
1768                 }
1769         }
1770
1771         if (needs_io && !zfs_no_scrub_io) {
1772                 vdev_t *rvd = spa->spa_root_vdev;
1773                 uint64_t maxinflight = rvd->vdev_children *
1774                     MAX(zfs_top_maxinflight, 1);
1775                 void *data = zio_data_buf_alloc(size);
1776
1777                 mutex_enter(&spa->spa_scrub_lock);
1778                 while (spa->spa_scrub_inflight >= maxinflight)
1779                         cv_wait(&spa->spa_scrub_io_cv, &spa->spa_scrub_lock);
1780                 spa->spa_scrub_inflight++;
1781                 mutex_exit(&spa->spa_scrub_lock);
1782
1783                 /*
1784                  * If we're seeing recent (zfs_scan_idle) "important" I/Os
1785                  * then throttle our workload to limit the impact of a scan.
1786                  */
1787                 if (ddi_get_lbolt64() - spa->spa_last_io <= zfs_scan_idle)
1788                         delay(MAX((int)scan_delay, 0));
1789
1790                 zio_nowait(zio_read(NULL, spa, bp, data, size,
1791                     dsl_scan_scrub_done, NULL, ZIO_PRIORITY_SCRUB,
1792                     zio_flags, zb));
1793         }
1794
1795         /* do not relocate this block */
1796         return (0);
1797 }
1798
1799 int
1800 dsl_scan(dsl_pool_t *dp, pool_scan_func_t func)
1801 {
1802         spa_t *spa = dp->dp_spa;
1803
1804         /*
1805          * Purge all vdev caches and probe all devices.  We do this here
1806          * rather than in sync context because this requires a writer lock
1807          * on the spa_config lock, which we can't do from sync context.  The
1808          * spa_scrub_reopen flag indicates that vdev_open() should not
1809          * attempt to start another scrub.
1810          */
1811         spa_vdev_state_enter(spa, SCL_NONE);
1812         spa->spa_scrub_reopen = B_TRUE;
1813         vdev_reopen(spa->spa_root_vdev);
1814         spa->spa_scrub_reopen = B_FALSE;
1815         (void) spa_vdev_state_exit(spa, NULL, 0);
1816
1817         return (dsl_sync_task(spa_name(spa), dsl_scan_setup_check,
1818             dsl_scan_setup_sync, &func, 0, ZFS_SPACE_CHECK_NONE));
1819 }