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) 2013 by Delphix. All rights reserved.
  24  */
  25
  26 #include <sys/dsl_scan.h>
  27 #include <sys/dsl_pool.h>
  28 #include <sys/dsl_dataset.h>
  29 #include <sys/dsl_prop.h>
  30 #include <sys/dsl_dir.h>
  31 #include <sys/dsl_synctask.h>
  32 #include <sys/dnode.h>
  33 #include <sys/dmu_tx.h>
  34 #include <sys/dmu_objset.h>
  35 #include <sys/arc.h>
  36 #include <sys/zap.h>
  37 #include <sys/zio.h>
  38 #include <sys/zfs_context.h>
  39 #include <sys/fs/zfs.h>
  40 #include <sys/zfs_znode.h>
  41 #include <sys/spa_impl.h>
  42 #include <sys/vdev_impl.h>
  43 #include <sys/zil_impl.h>
  44 #include <sys/zio_checksum.h>
  45 #include <sys/ddt.h>
  46 #include <sys/sa.h>
  47 #include <sys/sa_impl.h>
  48 #include <sys/zfeature.h>
  49 #ifdef _KERNEL
  50 #include <sys/zfs_vfsops.h>
  51 #endif
  52
  53 typedef int (scan_cb_t)(dsl_pool_t *, const blkptr_t *, const zbookmark_t *);
  54
  55 static scan_cb_t dsl_scan_defrag_cb;
  56 static scan_cb_t dsl_scan_scrub_cb;
  57 static scan_cb_t dsl_scan_remove_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 *tx);
  60
  61 unsigned int zfs_top_maxinflight = 32;  /* maximum I/Os per top-level */
  62 unsigned int zfs_resilver_delay = 2;    /* number of ticks to delay resilver */
  63 unsigned int zfs_scrub_delay = 4;       /* number of ticks to delay scrub */
  64 unsigned int zfs_scan_idle = 50;        /* idle window in clock ticks */
  65
  66 unsigned int zfs_scan_min_time_ms = 1000; /* min millisecs to scrub per txg */
  67 unsigned int zfs_free_min_time_ms = 1000; /* min millisecs to free per txg */
  68 unsigned int zfs_resilver_min_time_ms = 3000; /* min millisecs to resilver
  69                                                  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 srub prefetching */
  72
  73 SYSCTL_DECL(_vfs_zfs);
  74 TUNABLE_INT("vfs.zfs.top_maxinflight", &zfs_top_maxinflight);
  75 SYSCTL_UINT(_vfs_zfs, OID_AUTO, top_maxinflight, CTLFLAG_RW,
  76     &zfs_top_maxinflight, 0, "Maximum I/Os per top-level vdev");
  77 TUNABLE_INT("vfs.zfs.resilver_delay", &zfs_resilver_delay);
  78 SYSCTL_UINT(_vfs_zfs, OID_AUTO, resilver_delay, CTLFLAG_RW,
  79     &zfs_resilver_delay, 0, "Number of ticks to delay resilver");
  80 TUNABLE_INT("vfs.zfs.scrub_delay", &zfs_scrub_delay);
  81 SYSCTL_UINT(_vfs_zfs, OID_AUTO, scrub_delay, CTLFLAG_RW,
  82     &zfs_scrub_delay, 0, "Number of ticks to delay scrub");
  83 TUNABLE_INT("vfs.zfs.scan_idle", &zfs_scan_idle);
  84 SYSCTL_UINT(_vfs_zfs, OID_AUTO, scan_idle, CTLFLAG_RW,
  85     &zfs_scan_idle, 0, "Idle scan window in clock ticks");
  86 TUNABLE_INT("vfs.zfs.scan_min_time_ms", &zfs_scan_min_time_ms);
  87 SYSCTL_UINT(_vfs_zfs, OID_AUTO, scan_min_time_ms, CTLFLAG_RW,
  88     &zfs_scan_min_time_ms, 0, "Min millisecs to scrub per txg");
  89 TUNABLE_INT("vfs.zfs.free_min_time_ms", &zfs_free_min_time_ms);
  90 SYSCTL_UINT(_vfs_zfs, OID_AUTO, free_min_time_ms, CTLFLAG_RW,
  91     &zfs_free_min_time_ms, 0, "Min millisecs to free per txg");
  92 TUNABLE_INT("vfs.zfs.resilver_min_time_ms", &zfs_resilver_min_time_ms);
  93 SYSCTL_UINT(_vfs_zfs, OID_AUTO, resilver_min_time_ms, CTLFLAG_RW,
  94     &zfs_resilver_min_time_ms, 0, "Min millisecs to resilver per txg");
  95 TUNABLE_INT("vfs.zfs.no_scrub_io", &zfs_no_scrub_io);
  96 SYSCTL_INT(_vfs_zfs, OID_AUTO, no_scrub_io, CTLFLAG_RW,
  97     &zfs_no_scrub_io, 0, "Disable scrub I/O");
  98 TUNABLE_INT("vfs.zfs.no_scrub_prefetch", &zfs_no_scrub_prefetch);
  99 SYSCTL_INT(_vfs_zfs, OID_AUTO, no_scrub_prefetch, CTLFLAG_RW,
 100     &zfs_no_scrub_prefetch, 0, "Disable scrub prefetching");
 101
 102 enum ddt_class zfs_scrub_ddt_class_max = DDT_CLASS_DUPLICATE;
 103
 104 #define DSL_SCAN_IS_SCRUB_RESILVER(scn) \
 105         ((scn)->scn_phys.scn_func == POOL_SCAN_SCRUB || \
 106         (scn)->scn_phys.scn_func == POOL_SCAN_RESILVER)
 107
 108 extern int zfs_txg_timeout;
 109
 110 /* the order has to match pool_scan_type */
 111 static scan_cb_t *scan_funcs[POOL_SCAN_FUNCS] = {
 112         NULL,
 113         dsl_scan_scrub_cb,      /* POOL_SCAN_SCRUB */
 114         dsl_scan_scrub_cb,      /* POOL_SCAN_RESILVER */
 115 };
 116
 117 int
 118 dsl_scan_init(dsl_pool_t *dp, uint64_t txg)
 119 {
 120         int err;
 121         dsl_scan_t *scn;
 122         spa_t *spa = dp->dp_spa;
 123         uint64_t f;
 124
 125         scn = dp->dp_scan = kmem_zalloc(sizeof (dsl_scan_t), KM_SLEEP);
 126         scn->scn_dp = dp;
 127
 128         /*
 129          * It's possible that we're resuming a scan after a reboot so
 130          * make sure that the scan_async_destroying flag is initialized
 131          * appropriately.
 132          */
 133         ASSERT(!scn->scn_async_destroying);
 134         scn->scn_async_destroying = spa_feature_is_active(dp->dp_spa,
 135             &spa_feature_table[SPA_FEATURE_ASYNC_DESTROY]);
 136
 137         err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 138             "scrub_func", sizeof (uint64_t), 1, &f);
 139         if (err == 0) {
 140                 /*
 141                  * There was an old-style scrub in progress.  Restart a
 142                  * new-style scrub from the beginning.
 143                  */
 144                 scn->scn_restart_txg = txg;
 145                 zfs_dbgmsg("old-style scrub was in progress; "
 146                     "restarting new-style scrub in txg %llu",
 147                     scn->scn_restart_txg);
 148
 149                 /*
 150                  * Load the queue obj from the old location so that it
 151                  * can be freed by dsl_scan_done().
 152                  */
 153                 (void) zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 154                     "scrub_queue", sizeof (uint64_t), 1,
 155                     &scn->scn_phys.scn_queue_obj);
 156         } else {
 157                 err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 158                     DMU_POOL_SCAN, sizeof (uint64_t), SCAN_PHYS_NUMINTS,
 159                     &scn->scn_phys);
 160                 if (err == ENOENT)
 161                         return (0);
 162                 else if (err)
 163                         return (err);
 164
 165                 if (scn->scn_phys.scn_state == DSS_SCANNING &&
 166                     spa_prev_software_version(dp->dp_spa) < SPA_VERSION_SCAN) {
 167                         /*
 168                          * A new-type scrub was in progress on an old
 169                          * pool, and the pool was accessed by old
 170                          * software.  Restart from the beginning, since
 171                          * the old software may have changed the pool in
 172                          * the meantime.
 173                          */
 174                         scn->scn_restart_txg = txg;
 175                         zfs_dbgmsg("new-style scrub was modified "
 176                             "by old software; restarting in txg %llu",
 177                             scn->scn_restart_txg);
 178                 }
 179         }
 180
 181         spa_scan_stat_init(spa);
 182         return (0);
 183 }
 184
 185 void
 186 dsl_scan_fini(dsl_pool_t *dp)
 187 {
 188         if (dp->dp_scan) {
 189                 kmem_free(dp->dp_scan, sizeof (dsl_scan_t));
 190                 dp->dp_scan = NULL;
 191         }
 192 }
 193
 194 /* ARGSUSED */
 195 static int
 196 dsl_scan_setup_check(void *arg, dmu_tx_t *tx)
 197 {
 198         dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan;
 199
 200         if (scn->scn_phys.scn_state == DSS_SCANNING)
 201                 return (SET_ERROR(EBUSY));
 202
 203         return (0);
 204 }
 205
 206 static void
 207 dsl_scan_setup_sync(void *arg, dmu_tx_t *tx)
 208 {
 209         dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan;
 210         pool_scan_func_t *funcp = arg;
 211         dmu_object_type_t ot = 0;
 212         dsl_pool_t *dp = scn->scn_dp;
 213         spa_t *spa = dp->dp_spa;
 214
 215         ASSERT(scn->scn_phys.scn_state != DSS_SCANNING);
 216         ASSERT(*funcp > POOL_SCAN_NONE && *funcp < POOL_SCAN_FUNCS);
 217         bzero(&scn->scn_phys, sizeof (scn->scn_phys));
 218         scn->scn_phys.scn_func = *funcp;
 219         scn->scn_phys.scn_state = DSS_SCANNING;
 220         scn->scn_phys.scn_min_txg = 0;
 221         scn->scn_phys.scn_max_txg = tx->tx_txg;
 222         scn->scn_phys.scn_ddt_class_max = DDT_CLASSES - 1; /* the entire DDT */
 223         scn->scn_phys.scn_start_time = gethrestime_sec();
 224         scn->scn_phys.scn_errors = 0;
 225         scn->scn_phys.scn_to_examine = spa->spa_root_vdev->vdev_stat.vs_alloc;
 226         scn->scn_restart_txg = 0;
 227         spa_scan_stat_init(spa);
 228
 229         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
 230                 scn->scn_phys.scn_ddt_class_max = zfs_scrub_ddt_class_max;
 231
 232                 /* rewrite all disk labels */
 233                 vdev_config_dirty(spa->spa_root_vdev);
 234
 235                 if (vdev_resilver_needed(spa->spa_root_vdev,
 236                     &scn->scn_phys.scn_min_txg, &scn->scn_phys.scn_max_txg)) {
 237                         spa_event_notify(spa, NULL, ESC_ZFS_RESILVER_START);
 238                 } else {
 239                         spa_event_notify(spa, NULL, ESC_ZFS_SCRUB_START);
 240                 }
 241
 242                 spa->spa_scrub_started = B_TRUE;
 243                 /*
 244                  * If this is an incremental scrub, limit the DDT scrub phase
 245                  * to just the auto-ditto class (for correctness); the rest
 246                  * of the scrub should go faster using top-down pruning.
 247                  */
 248                 if (scn->scn_phys.scn_min_txg > TXG_INITIAL)
 249                         scn->scn_phys.scn_ddt_class_max = DDT_CLASS_DITTO;
 250
 251         }
 252
 253         /* back to the generic stuff */
 254
 255         if (dp->dp_blkstats == NULL) {
 256                 dp->dp_blkstats =
 257                     kmem_alloc(sizeof (zfs_all_blkstats_t), KM_SLEEP);
 258         }
 259         bzero(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
 260
 261         if (spa_version(spa) < SPA_VERSION_DSL_SCRUB)
 262                 ot = DMU_OT_ZAP_OTHER;
 263
 264         scn->scn_phys.scn_queue_obj = zap_create(dp->dp_meta_objset,
 265             ot ? ot : DMU_OT_SCAN_QUEUE, DMU_OT_NONE, 0, tx);
 266
 267         dsl_scan_sync_state(scn, tx);
 268
 269         spa_history_log_internal(spa, "scan setup", tx,
 270             "func=%u mintxg=%llu maxtxg=%llu",
 271             *funcp, scn->scn_phys.scn_min_txg, scn->scn_phys.scn_max_txg);
 272 }
 273
 274 /* ARGSUSED */
 275 static void
 276 dsl_scan_done(dsl_scan_t *scn, boolean_t complete, dmu_tx_t *tx)
 277 {
 278         static const char *old_names[] = {
 279                 "scrub_bookmark",
 280                 "scrub_ddt_bookmark",
 281                 "scrub_ddt_class_max",
 282                 "scrub_queue",
 283                 "scrub_min_txg",
 284                 "scrub_max_txg",
 285                 "scrub_func",
 286                 "scrub_errors",
 287                 NULL
 288         };
 289
 290         dsl_pool_t *dp = scn->scn_dp;
 291         spa_t *spa = dp->dp_spa;
 292         int i;
 293
 294         /* Remove any remnants of an old-style scrub. */
 295         for (i = 0; old_names[i]; i++) {
 296                 (void) zap_remove(dp->dp_meta_objset,
 297                     DMU_POOL_DIRECTORY_OBJECT, old_names[i], tx);
 298         }
 299
 300         if (scn->scn_phys.scn_queue_obj != 0) {
 301                 VERIFY(0 == dmu_object_free(dp->dp_meta_objset,
 302                     scn->scn_phys.scn_queue_obj, tx));
 303                 scn->scn_phys.scn_queue_obj = 0;
 304         }
 305
 306         /*
 307          * If we were "restarted" from a stopped state, don't bother
 308          * with anything else.
 309          */
 310         if (scn->scn_phys.scn_state != DSS_SCANNING)
 311                 return;
 312
 313         if (complete)
 314                 scn->scn_phys.scn_state = DSS_FINISHED;
 315         else
 316                 scn->scn_phys.scn_state = DSS_CANCELED;
 317
 318         spa_history_log_internal(spa, "scan done", tx,
 319             "complete=%u", complete);
 320
 321         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
 322                 mutex_enter(&spa->spa_scrub_lock);
 323                 while (spa->spa_scrub_inflight > 0) {
 324                         cv_wait(&spa->spa_scrub_io_cv,
 325                             &spa->spa_scrub_lock);
 326                 }
 327                 mutex_exit(&spa->spa_scrub_lock);
 328                 spa->spa_scrub_started = B_FALSE;
 329                 spa->spa_scrub_active = B_FALSE;
 330
 331                 /*
 332                  * If the scrub/resilver completed, update all DTLs to
 333                  * reflect this.  Whether it succeeded or not, vacate
 334                  * all temporary scrub DTLs.
 335                  */
 336                 vdev_dtl_reassess(spa->spa_root_vdev, tx->tx_txg,
 337                     complete ? scn->scn_phys.scn_max_txg : 0, B_TRUE);
 338                 if (complete) {
 339                         spa_event_notify(spa, NULL, scn->scn_phys.scn_min_txg ?
 340                             ESC_ZFS_RESILVER_FINISH : ESC_ZFS_SCRUB_FINISH);
 341                 }
 342                 spa_errlog_rotate(spa);
 343
 344                 /*
 345                  * We may have finished replacing a device.
 346                  * Let the async thread assess this and handle the detach.
 347                  */
 348                 spa_async_request(spa, SPA_ASYNC_RESILVER_DONE);
 349         }
 350
 351         scn->scn_phys.scn_end_time = gethrestime_sec();
 352 }
 353
 354 /* ARGSUSED */
 355 static int
 356 dsl_scan_cancel_check(void *arg, dmu_tx_t *tx)
 357 {
 358         dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan;
 359
 360         if (scn->scn_phys.scn_state != DSS_SCANNING)
 361                 return (SET_ERROR(ENOENT));
 362         return (0);
 363 }
 364
 365 /* ARGSUSED */
 366 static void
 367 dsl_scan_cancel_sync(void *arg, dmu_tx_t *tx)
 368 {
 369         dsl_scan_t *scn = dmu_tx_pool(tx)->dp_scan;
 370
 371         dsl_scan_done(scn, B_FALSE, tx);
 372         dsl_scan_sync_state(scn, tx);
 373 }
 374
 375 int
 376 dsl_scan_cancel(dsl_pool_t *dp)
 377 {
 378         return (dsl_sync_task(spa_name(dp->dp_spa), dsl_scan_cancel_check,
 379             dsl_scan_cancel_sync, NULL, 3));
 380 }
 381
 382 static void dsl_scan_visitbp(blkptr_t *bp,
 383     const zbookmark_t *zb, dnode_phys_t *dnp, arc_buf_t *pbuf,
 384     dsl_dataset_t *ds, dsl_scan_t *scn, dmu_objset_type_t ostype,
 385     dmu_tx_t *tx);
 386 static void dsl_scan_visitdnode(dsl_scan_t *, dsl_dataset_t *ds,
 387     dmu_objset_type_t ostype,
 388     dnode_phys_t *dnp, arc_buf_t *buf, uint64_t object, dmu_tx_t *tx);
 389
 390 void
 391 dsl_free(dsl_pool_t *dp, uint64_t txg, const blkptr_t *bp)
 392 {
 393         zio_free(dp->dp_spa, txg, bp);
 394 }
 395
 396 void
 397 dsl_free_sync(zio_t *pio, dsl_pool_t *dp, uint64_t txg, const blkptr_t *bpp)
 398 {
 399         ASSERT(dsl_pool_sync_context(dp));
 400         zio_nowait(zio_free_sync(pio, dp->dp_spa, txg, bpp, pio->io_flags));
 401 }
 402
 403 static uint64_t
 404 dsl_scan_ds_maxtxg(dsl_dataset_t *ds)
 405 {
 406         uint64_t smt = ds->ds_dir->dd_pool->dp_scan->scn_phys.scn_max_txg;
 407         if (dsl_dataset_is_snapshot(ds))
 408                 return (MIN(smt, ds->ds_phys->ds_creation_txg));
 409         return (smt);
 410 }
 411
 412 static void
 413 dsl_scan_sync_state(dsl_scan_t *scn, dmu_tx_t *tx)
 414 {
 415         VERIFY0(zap_update(scn->scn_dp->dp_meta_objset,
 416             DMU_POOL_DIRECTORY_OBJECT,
 417             DMU_POOL_SCAN, sizeof (uint64_t), SCAN_PHYS_NUMINTS,
 418             &scn->scn_phys, tx));
 419 }
 420
 421 static boolean_t
 422 dsl_scan_check_pause(dsl_scan_t *scn, const zbookmark_t *zb)
 423 {
 424         uint64_t elapsed_nanosecs;
 425         unsigned int mintime;
 426
 427         /* we never skip user/group accounting objects */
 428         if (zb && (int64_t)zb->zb_object < 0)
 429                 return (B_FALSE);
 430
 431         if (scn->scn_pausing)
 432                 return (B_TRUE); /* we're already pausing */
 433
 434         if (!ZB_IS_ZERO(&scn->scn_phys.scn_bookmark))
 435                 return (B_FALSE); /* we're resuming */
 436
 437         /* We only know how to resume from level-0 blocks. */
 438         if (zb && zb->zb_level != 0)
 439                 return (B_FALSE);
 440
 441         mintime = (scn->scn_phys.scn_func == POOL_SCAN_RESILVER) ?
 442             zfs_resilver_min_time_ms : zfs_scan_min_time_ms;
 443         elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
 444         if (elapsed_nanosecs / NANOSEC > zfs_txg_timeout ||
 445             (elapsed_nanosecs / MICROSEC > mintime &&
 446             txg_sync_waiting(scn->scn_dp)) ||
 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_t zb;
 481
 482         if (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_t zb;
 513
 514                 if (bp->blk_birth <= scn->scn_phys.scn_cur_min_txg)
 515                         return (0);
 516
 517                 /*
 518                  * birth can be < claim_txg if this record's txg is
 519                  * already txg sync'ed (but this log block contains
 520                  * other records that are not synced)
 521                  */
 522                 if (claim_txg == 0 || bp->blk_birth < claim_txg)
 523                         return (0);
 524
 525                 SET_BOOKMARK(&zb, zh->zh_log.blk_cksum.zc_word[ZIL_ZC_OBJSET],
 526                     lr->lr_foid, ZB_ZIL_LEVEL,
 527                     lr->lr_offset / BP_GET_LSIZE(bp));
 528
 529                 VERIFY(0 == scan_funcs[scn->scn_phys.scn_func](dp, bp, &zb));
 530         }
 531         return (0);
 532 }
 533
 534 static void
 535 dsl_scan_zil(dsl_pool_t *dp, zil_header_t *zh)
 536 {
 537         uint64_t claim_txg = zh->zh_claim_txg;
 538         zil_scan_arg_t zsa = { dp, zh };
 539         zilog_t *zilog;
 540
 541         /*
 542          * We only want to visit blocks that have been claimed but not yet
 543          * replayed (or, in read-only mode, blocks that *would* be claimed).
 544          */
 545         if (claim_txg == 0 && spa_writeable(dp->dp_spa))
 546                 return;
 547
 548         zilog = zil_alloc(dp->dp_meta_objset, zh);
 549
 550         (void) zil_parse(zilog, dsl_scan_zil_block, dsl_scan_zil_record, &zsa,
 551             claim_txg);
 552
 553         zil_free(zilog);
 554 }
 555
 556 /* ARGSUSED */
 557 static void
 558 dsl_scan_prefetch(dsl_scan_t *scn, arc_buf_t *buf, blkptr_t *bp,
 559     uint64_t objset, uint64_t object, uint64_t blkid)
 560 {
 561         zbookmark_t czb;
 562         uint32_t flags = ARC_NOWAIT | ARC_PREFETCH;
 563
 564         if (zfs_no_scrub_prefetch)
 565                 return;
 566
 567         if (BP_IS_HOLE(bp) || bp->blk_birth <= scn->scn_phys.scn_min_txg ||
 568             (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_DNODE))
 569                 return;
 570
 571         SET_BOOKMARK(&czb, objset, object, BP_GET_LEVEL(bp), blkid);
 572
 573         (void) arc_read(scn->scn_zio_root, scn->scn_dp->dp_spa, bp,
 574             NULL, NULL, ZIO_PRIORITY_ASYNC_READ,
 575             ZIO_FLAG_CANFAIL | ZIO_FLAG_SCAN_THREAD, &flags, &czb);
 576 }
 577
 578 static boolean_t
 579 dsl_scan_check_resume(dsl_scan_t *scn, const dnode_phys_t *dnp,
 580     const zbookmark_t *zb)
 581 {
 582         /*
 583          * We never skip over user/group accounting objects (obj<0)
 584          */
 585         if (!ZB_IS_ZERO(&scn->scn_phys.scn_bookmark) &&
 586             (int64_t)zb->zb_object >= 0) {
 587                 /*
 588                  * If we already visited this bp & everything below (in
 589                  * a prior txg sync), don't bother doing it again.
 590                  */
 591                 if (zbookmark_is_before(dnp, zb, &scn->scn_phys.scn_bookmark))
 592                         return (B_TRUE);
 593
 594                 /*
 595                  * If we found the block we're trying to resume from, or
 596                  * we went past it to a different object, zero it out to
 597                  * indicate that it's OK to start checking for pausing
 598                  * again.
 599                  */
 600                 if (bcmp(zb, &scn->scn_phys.scn_bookmark, sizeof (*zb)) == 0 ||
 601                     zb->zb_object > scn->scn_phys.scn_bookmark.zb_object) {
 602                         dprintf("resuming at %llx/%llx/%llx/%llx\n",
 603                             (longlong_t)zb->zb_objset,
 604                             (longlong_t)zb->zb_object,
 605                             (longlong_t)zb->zb_level,
 606                             (longlong_t)zb->zb_blkid);
 607                         bzero(&scn->scn_phys.scn_bookmark, sizeof (*zb));
 608                 }
 609         }
 610         return (B_FALSE);
 611 }
 612
 613 /*
 614  * Return nonzero on i/o error.
 615  * Return new buf to write out in *bufp.
 616  */
 617 static int
 618 dsl_scan_recurse(dsl_scan_t *scn, dsl_dataset_t *ds, dmu_objset_type_t ostype,
 619     dnode_phys_t *dnp, const blkptr_t *bp,
 620     const zbookmark_t *zb, dmu_tx_t *tx, arc_buf_t **bufp)
 621 {
 622         dsl_pool_t *dp = scn->scn_dp;
 623         int zio_flags = ZIO_FLAG_CANFAIL | ZIO_FLAG_SCAN_THREAD;
 624         int err;
 625
 626         if (BP_GET_LEVEL(bp) > 0) {
 627                 uint32_t flags = ARC_WAIT;
 628                 int i;
 629                 blkptr_t *cbp;
 630                 int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT;
 631
 632                 err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, bufp,
 633                     ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
 634                 if (err) {
 635                         scn->scn_phys.scn_errors++;
 636                         return (err);
 637                 }
 638                 for (i = 0, cbp = (*bufp)->b_data; i < epb; i++, cbp++) {
 639                         dsl_scan_prefetch(scn, *bufp, cbp, zb->zb_objset,
 640                             zb->zb_object, zb->zb_blkid * epb + i);
 641                 }
 642                 for (i = 0, cbp = (*bufp)->b_data; i < epb; i++, cbp++) {
 643                         zbookmark_t czb;
 644
 645                         SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
 646                             zb->zb_level - 1,
 647                             zb->zb_blkid * epb + i);
 648                         dsl_scan_visitbp(cbp, &czb, dnp,
 649                             *bufp, ds, scn, ostype, tx);
 650                 }
 651         } else if (BP_GET_TYPE(bp) == DMU_OT_USERGROUP_USED) {
 652                 uint32_t flags = ARC_WAIT;
 653
 654                 err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, bufp,
 655                     ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
 656                 if (err) {
 657                         scn->scn_phys.scn_errors++;
 658                         return (err);
 659                 }
 660         } else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) {
 661                 uint32_t flags = ARC_WAIT;
 662                 dnode_phys_t *cdnp;
 663                 int i, j;
 664                 int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT;
 665
 666                 err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, bufp,
 667                     ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
 668                 if (err) {
 669                         scn->scn_phys.scn_errors++;
 670                         return (err);
 671                 }
 672                 for (i = 0, cdnp = (*bufp)->b_data; i < epb; i++, cdnp++) {
 673                         for (j = 0; j < cdnp->dn_nblkptr; j++) {
 674                                 blkptr_t *cbp = &cdnp->dn_blkptr[j];
 675                                 dsl_scan_prefetch(scn, *bufp, cbp,
 676                                     zb->zb_objset, zb->zb_blkid * epb + i, j);
 677                         }
 678                 }
 679                 for (i = 0, cdnp = (*bufp)->b_data; i < epb; i++, cdnp++) {
 680                         dsl_scan_visitdnode(scn, ds, ostype,
 681                             cdnp, *bufp, zb->zb_blkid * epb + i, tx);
 682                 }
 683
 684         } else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) {
 685                 uint32_t flags = ARC_WAIT;
 686                 objset_phys_t *osp;
 687
 688                 err = arc_read(NULL, dp->dp_spa, bp, arc_getbuf_func, bufp,
 689                     ZIO_PRIORITY_ASYNC_READ, zio_flags, &flags, zb);
 690                 if (err) {
 691                         scn->scn_phys.scn_errors++;
 692                         return (err);
 693                 }
 694
 695                 osp = (*bufp)->b_data;
 696
 697                 dsl_scan_visitdnode(scn, ds, osp->os_type,
 698                     &osp->os_meta_dnode, *bufp, DMU_META_DNODE_OBJECT, tx);
 699
 700                 if (OBJSET_BUF_HAS_USERUSED(*bufp)) {
 701                         /*
 702                          * We also always visit user/group accounting
 703                          * objects, and never skip them, even if we are
 704                          * pausing.  This is necessary so that the space
 705                          * deltas from this txg get integrated.
 706                          */
 707                         dsl_scan_visitdnode(scn, ds, osp->os_type,
 708                             &osp->os_groupused_dnode, *bufp,
 709                             DMU_GROUPUSED_OBJECT, tx);
 710                         dsl_scan_visitdnode(scn, ds, osp->os_type,
 711                             &osp->os_userused_dnode, *bufp,
 712                             DMU_USERUSED_OBJECT, tx);
 713                 }
 714         }
 715
 716         return (0);
 717 }
 718
 719 static void
 720 dsl_scan_visitdnode(dsl_scan_t *scn, dsl_dataset_t *ds,
 721     dmu_objset_type_t ostype, dnode_phys_t *dnp, arc_buf_t *buf,
 722     uint64_t object, dmu_tx_t *tx)
 723 {
 724         int j;
 725
 726         for (j = 0; j < dnp->dn_nblkptr; j++) {
 727                 zbookmark_t czb;
 728
 729                 SET_BOOKMARK(&czb, ds ? ds->ds_object : 0, object,
 730                     dnp->dn_nlevels - 1, j);
 731                 dsl_scan_visitbp(&dnp->dn_blkptr[j],
 732                     &czb, dnp, buf, ds, scn, ostype, tx);
 733         }
 734
 735         if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
 736                 zbookmark_t czb;
 737                 SET_BOOKMARK(&czb, ds ? ds->ds_object : 0, object,
 738                     0, DMU_SPILL_BLKID);
 739                 dsl_scan_visitbp(&dnp->dn_spill,
 740                     &czb, dnp, buf, ds, scn, ostype, tx);
 741         }
 742 }
 743
 744 /*
 745  * The arguments are in this order because mdb can only print the
 746  * first 5; we want them to be useful.
 747  */
 748 static void
 749 dsl_scan_visitbp(blkptr_t *bp, const zbookmark_t *zb,
 750     dnode_phys_t *dnp, arc_buf_t *pbuf,
 751     dsl_dataset_t *ds, dsl_scan_t *scn, dmu_objset_type_t ostype,
 752     dmu_tx_t *tx)
 753 {
 754         dsl_pool_t *dp = scn->scn_dp;
 755         arc_buf_t *buf = NULL;
 756         blkptr_t bp_toread = *bp;
 757
 758         /* ASSERT(pbuf == NULL || arc_released(pbuf)); */
 759
 760         if (dsl_scan_check_pause(scn, zb))
 761                 return;
 762
 763         if (dsl_scan_check_resume(scn, dnp, zb))
 764                 return;
 765
 766         if (bp->blk_birth == 0)
 767                 return;
 768
 769         scn->scn_visited_this_txg++;
 770
 771         dprintf_bp(bp,
 772             "visiting ds=%p/%llu zb=%llx/%llx/%llx/%llx buf=%p bp=%p",
 773             ds, ds ? ds->ds_object : 0,
 774             zb->zb_objset, zb->zb_object, zb->zb_level, zb->zb_blkid,
 775             pbuf, bp);
 776
 777         if (bp->blk_birth <= scn->scn_phys.scn_cur_min_txg)
 778                 return;
 779
 780         if (dsl_scan_recurse(scn, ds, ostype, dnp, &bp_toread, zb, tx,
 781             &buf) != 0)
 782                 return;
 783
 784         /*
 785          * If dsl_scan_ddt() has aready visited this block, it will have
 786          * already done any translations or scrubbing, so don't call the
 787          * callback again.
 788          */
 789         if (ddt_class_contains(dp->dp_spa,
 790             scn->scn_phys.scn_ddt_class_max, bp)) {
 791                 ASSERT(buf == NULL);
 792                 return;
 793         }
 794
 795         /*
 796          * If this block is from the future (after cur_max_txg), then we
 797          * are doing this on behalf of a deleted snapshot, and we will
 798          * revisit the future block on the next pass of this dataset.
 799          * Don't scan it now unless we need to because something
 800          * under it was modified.
 801          */
 802         if (bp->blk_birth <= scn->scn_phys.scn_cur_max_txg) {
 803                 scan_funcs[scn->scn_phys.scn_func](dp, bp, zb);
 804         }
 805         if (buf)
 806                 (void) arc_buf_remove_ref(buf, &buf);
 807 }
 808
 809 static void
 810 dsl_scan_visit_rootbp(dsl_scan_t *scn, dsl_dataset_t *ds, blkptr_t *bp,
 811     dmu_tx_t *tx)
 812 {
 813         zbookmark_t zb;
 814
 815         SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
 816             ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
 817         dsl_scan_visitbp(bp, &zb, NULL, NULL,
 818             ds, scn, DMU_OST_NONE, tx);
 819
 820         dprintf_ds(ds, "finished scan%s", "");
 821 }
 822
 823 void
 824 dsl_scan_ds_destroyed(dsl_dataset_t *ds, dmu_tx_t *tx)
 825 {
 826         dsl_pool_t *dp = ds->ds_dir->dd_pool;
 827         dsl_scan_t *scn = dp->dp_scan;
 828         uint64_t mintxg;
 829
 830         if (scn->scn_phys.scn_state != DSS_SCANNING)
 831                 return;
 832
 833         if (scn->scn_phys.scn_bookmark.zb_objset == ds->ds_object) {
 834                 if (dsl_dataset_is_snapshot(ds)) {
 835                         /* Note, scn_cur_{min,max}_txg stays the same. */
 836                         scn->scn_phys.scn_bookmark.zb_objset =
 837                             ds->ds_phys->ds_next_snap_obj;
 838                         zfs_dbgmsg("destroying ds %llu; currently traversing; "
 839                             "reset zb_objset to %llu",
 840                             (u_longlong_t)ds->ds_object,
 841                             (u_longlong_t)ds->ds_phys->ds_next_snap_obj);
 842                         scn->scn_phys.scn_flags |= DSF_VISIT_DS_AGAIN;
 843                 } else {
 844                         SET_BOOKMARK(&scn->scn_phys.scn_bookmark,
 845                             ZB_DESTROYED_OBJSET, 0, 0, 0);
 846                         zfs_dbgmsg("destroying ds %llu; currently traversing; "
 847                             "reset bookmark to -1,0,0,0",
 848                             (u_longlong_t)ds->ds_object);
 849                 }
 850         } else if (zap_lookup_int_key(dp->dp_meta_objset,
 851             scn->scn_phys.scn_queue_obj, ds->ds_object, &mintxg) == 0) {
 852                 ASSERT3U(ds->ds_phys->ds_num_children, <=, 1);
 853                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 854                     scn->scn_phys.scn_queue_obj, ds->ds_object, tx));
 855                 if (dsl_dataset_is_snapshot(ds)) {
 856                         /*
 857                          * We keep the same mintxg; it could be >
 858                          * ds_creation_txg if the previous snapshot was
 859                          * deleted too.
 860                          */
 861                         VERIFY(zap_add_int_key(dp->dp_meta_objset,
 862                             scn->scn_phys.scn_queue_obj,
 863                             ds->ds_phys->ds_next_snap_obj, mintxg, tx) == 0);
 864                         zfs_dbgmsg("destroying ds %llu; in queue; "
 865                             "replacing with %llu",
 866                             (u_longlong_t)ds->ds_object,
 867                             (u_longlong_t)ds->ds_phys->ds_next_snap_obj);
 868                 } else {
 869                         zfs_dbgmsg("destroying ds %llu; in queue; removing",
 870                             (u_longlong_t)ds->ds_object);
 871                 }
 872         } else {
 873                 zfs_dbgmsg("destroying ds %llu; ignoring",
 874                     (u_longlong_t)ds->ds_object);
 875         }
 876
 877         /*
 878          * dsl_scan_sync() should be called after this, and should sync
 879          * out our changed state, but just to be safe, do it here.
 880          */
 881         dsl_scan_sync_state(scn, tx);
 882 }
 883
 884 void
 885 dsl_scan_ds_snapshotted(dsl_dataset_t *ds, dmu_tx_t *tx)
 886 {
 887         dsl_pool_t *dp = ds->ds_dir->dd_pool;
 888         dsl_scan_t *scn = dp->dp_scan;
 889         uint64_t mintxg;
 890
 891         if (scn->scn_phys.scn_state != DSS_SCANNING)
 892                 return;
 893
 894         ASSERT(ds->ds_phys->ds_prev_snap_obj != 0);
 895
 896         if (scn->scn_phys.scn_bookmark.zb_objset == ds->ds_object) {
 897                 scn->scn_phys.scn_bookmark.zb_objset =
 898                     ds->ds_phys->ds_prev_snap_obj;
 899                 zfs_dbgmsg("snapshotting ds %llu; currently traversing; "
 900                     "reset zb_objset to %llu",
 901                     (u_longlong_t)ds->ds_object,
 902                     (u_longlong_t)ds->ds_phys->ds_prev_snap_obj);
 903         } else if (zap_lookup_int_key(dp->dp_meta_objset,
 904             scn->scn_phys.scn_queue_obj, ds->ds_object, &mintxg) == 0) {
 905                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 906                     scn->scn_phys.scn_queue_obj, ds->ds_object, tx));
 907                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
 908                     scn->scn_phys.scn_queue_obj,
 909                     ds->ds_phys->ds_prev_snap_obj, mintxg, tx) == 0);
 910                 zfs_dbgmsg("snapshotting ds %llu; in queue; "
 911                     "replacing with %llu",
 912                     (u_longlong_t)ds->ds_object,
 913                     (u_longlong_t)ds->ds_phys->ds_prev_snap_obj);
 914         }
 915         dsl_scan_sync_state(scn, tx);
 916 }
 917
 918 void
 919 dsl_scan_ds_clone_swapped(dsl_dataset_t *ds1, dsl_dataset_t *ds2, dmu_tx_t *tx)
 920 {
 921         dsl_pool_t *dp = ds1->ds_dir->dd_pool;
 922         dsl_scan_t *scn = dp->dp_scan;
 923         uint64_t mintxg;
 924
 925         if (scn->scn_phys.scn_state != DSS_SCANNING)
 926                 return;
 927
 928         if (scn->scn_phys.scn_bookmark.zb_objset == ds1->ds_object) {
 929                 scn->scn_phys.scn_bookmark.zb_objset = ds2->ds_object;
 930                 zfs_dbgmsg("clone_swap ds %llu; currently traversing; "
 931                     "reset zb_objset to %llu",
 932                     (u_longlong_t)ds1->ds_object,
 933                     (u_longlong_t)ds2->ds_object);
 934         } else if (scn->scn_phys.scn_bookmark.zb_objset == ds2->ds_object) {
 935                 scn->scn_phys.scn_bookmark.zb_objset = ds1->ds_object;
 936                 zfs_dbgmsg("clone_swap ds %llu; currently traversing; "
 937                     "reset zb_objset to %llu",
 938                     (u_longlong_t)ds2->ds_object,
 939                     (u_longlong_t)ds1->ds_object);
 940         }
 941
 942         if (zap_lookup_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
 943             ds1->ds_object, &mintxg) == 0) {
 944                 int err;
 945
 946                 ASSERT3U(mintxg, ==, ds1->ds_phys->ds_prev_snap_txg);
 947                 ASSERT3U(mintxg, ==, ds2->ds_phys->ds_prev_snap_txg);
 948                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 949                     scn->scn_phys.scn_queue_obj, ds1->ds_object, tx));
 950                 err = zap_add_int_key(dp->dp_meta_objset,
 951                     scn->scn_phys.scn_queue_obj, ds2->ds_object, mintxg, tx);
 952                 VERIFY(err == 0 || err == EEXIST);
 953                 if (err == EEXIST) {
 954                         /* Both were there to begin with */
 955                         VERIFY(0 == zap_add_int_key(dp->dp_meta_objset,
 956                             scn->scn_phys.scn_queue_obj,
 957                             ds1->ds_object, mintxg, tx));
 958                 }
 959                 zfs_dbgmsg("clone_swap ds %llu; in queue; "
 960                     "replacing with %llu",
 961                     (u_longlong_t)ds1->ds_object,
 962                     (u_longlong_t)ds2->ds_object);
 963         } else if (zap_lookup_int_key(dp->dp_meta_objset,
 964             scn->scn_phys.scn_queue_obj, ds2->ds_object, &mintxg) == 0) {
 965                 ASSERT3U(mintxg, ==, ds1->ds_phys->ds_prev_snap_txg);
 966                 ASSERT3U(mintxg, ==, ds2->ds_phys->ds_prev_snap_txg);
 967                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
 968                     scn->scn_phys.scn_queue_obj, ds2->ds_object, tx));
 969                 VERIFY(0 == zap_add_int_key(dp->dp_meta_objset,
 970                     scn->scn_phys.scn_queue_obj, ds1->ds_object, mintxg, tx));
 971                 zfs_dbgmsg("clone_swap ds %llu; in queue; "
 972                     "replacing with %llu",
 973                     (u_longlong_t)ds2->ds_object,
 974                     (u_longlong_t)ds1->ds_object);
 975         }
 976
 977         dsl_scan_sync_state(scn, tx);
 978 }
 979
 980 struct enqueue_clones_arg {
 981         dmu_tx_t *tx;
 982         uint64_t originobj;
 983 };
 984
 985 /* ARGSUSED */
 986 static int
 987 enqueue_clones_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg)
 988 {
 989         struct enqueue_clones_arg *eca = arg;
 990         dsl_dataset_t *ds;
 991         int err;
 992         dsl_scan_t *scn = dp->dp_scan;
 993
 994         if (hds->ds_dir->dd_phys->dd_origin_obj != eca->originobj)
 995                 return (0);
 996
 997         err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds);
 998         if (err)
 999                 return (err);
1000
1001         while (ds->ds_phys->ds_prev_snap_obj != eca->originobj) {
1002                 dsl_dataset_t *prev;
1003                 err = dsl_dataset_hold_obj(dp,
1004                     ds->ds_phys->ds_prev_snap_obj, FTAG, &prev);
1005
1006                 dsl_dataset_rele(ds, FTAG);
1007                 if (err)
1008                         return (err);
1009                 ds = prev;
1010         }
1011         VERIFY(zap_add_int_key(dp->dp_meta_objset,
1012             scn->scn_phys.scn_queue_obj, ds->ds_object,
1013             ds->ds_phys->ds_prev_snap_txg, eca->tx) == 0);
1014         dsl_dataset_rele(ds, FTAG);
1015         return (0);
1016 }
1017
1018 static void
1019 dsl_scan_visitds(dsl_scan_t *scn, uint64_t dsobj, dmu_tx_t *tx)
1020 {
1021         dsl_pool_t *dp = scn->scn_dp;
1022         dsl_dataset_t *ds;
1023         objset_t *os;
1024
1025         VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
1026
1027         if (dmu_objset_from_ds(ds, &os))
1028                 goto out;
1029
1030         /*
1031          * Only the ZIL in the head (non-snapshot) is valid.  Even though
1032          * snapshots can have ZIL block pointers (which may be the same
1033          * BP as in the head), they must be ignored.  So we traverse the
1034          * ZIL here, rather than in scan_recurse(), because the regular
1035          * snapshot block-sharing rules don't apply to it.
1036          */
1037         if (DSL_SCAN_IS_SCRUB_RESILVER(scn) && !dsl_dataset_is_snapshot(ds))
1038                 dsl_scan_zil(dp, &os->os_zil_header);
1039
1040         /*
1041          * Iterate over the bps in this ds.
1042          */
1043         dmu_buf_will_dirty(ds->ds_dbuf, tx);
1044         dsl_scan_visit_rootbp(scn, ds, &ds->ds_phys->ds_bp, tx);
1045
1046         char *dsname = kmem_alloc(ZFS_MAXNAMELEN, KM_SLEEP);
1047         dsl_dataset_name(ds, dsname);
1048         zfs_dbgmsg("scanned dataset %llu (%s) with min=%llu max=%llu; "
1049             "pausing=%u",
1050             (longlong_t)dsobj, dsname,
1051             (longlong_t)scn->scn_phys.scn_cur_min_txg,
1052             (longlong_t)scn->scn_phys.scn_cur_max_txg,
1053             (int)scn->scn_pausing);
1054         kmem_free(dsname, ZFS_MAXNAMELEN);
1055
1056         if (scn->scn_pausing)
1057                 goto out;
1058
1059         /*
1060          * We've finished this pass over this dataset.
1061          */
1062
1063         /*
1064          * If we did not completely visit this dataset, do another pass.
1065          */
1066         if (scn->scn_phys.scn_flags & DSF_VISIT_DS_AGAIN) {
1067                 zfs_dbgmsg("incomplete pass; visiting again");
1068                 scn->scn_phys.scn_flags &= ~DSF_VISIT_DS_AGAIN;
1069                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
1070                     scn->scn_phys.scn_queue_obj, ds->ds_object,
1071                     scn->scn_phys.scn_cur_max_txg, tx) == 0);
1072                 goto out;
1073         }
1074
1075         /*
1076          * Add descendent datasets to work queue.
1077          */
1078         if (ds->ds_phys->ds_next_snap_obj != 0) {
1079                 VERIFY(zap_add_int_key(dp->dp_meta_objset,
1080                     scn->scn_phys.scn_queue_obj, ds->ds_phys->ds_next_snap_obj,
1081                     ds->ds_phys->ds_creation_txg, tx) == 0);
1082         }
1083         if (ds->ds_phys->ds_num_children > 1) {
1084                 boolean_t usenext = B_FALSE;
1085                 if (ds->ds_phys->ds_next_clones_obj != 0) {
1086                         uint64_t count;
1087                         /*
1088                          * A bug in a previous version of the code could
1089                          * cause upgrade_clones_cb() to not set
1090                          * ds_next_snap_obj when it should, leading to a
1091                          * missing entry.  Therefore we can only use the
1092                          * next_clones_obj when its count is correct.
1093                          */
1094                         int err = zap_count(dp->dp_meta_objset,
1095                             ds->ds_phys->ds_next_clones_obj, &count);
1096                         if (err == 0 &&
1097                             count == ds->ds_phys->ds_num_children - 1)
1098                                 usenext = B_TRUE;
1099                 }
1100
1101                 if (usenext) {
1102                         VERIFY0(zap_join_key(dp->dp_meta_objset,
1103                             ds->ds_phys->ds_next_clones_obj,
1104                             scn->scn_phys.scn_queue_obj,
1105                             ds->ds_phys->ds_creation_txg, tx));
1106                 } else {
1107                         struct enqueue_clones_arg eca;
1108                         eca.tx = tx;
1109                         eca.originobj = ds->ds_object;
1110
1111                         VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
1112                             enqueue_clones_cb, &eca, DS_FIND_CHILDREN));
1113                 }
1114         }
1115
1116 out:
1117         dsl_dataset_rele(ds, FTAG);
1118 }
1119
1120 /* ARGSUSED */
1121 static int
1122 enqueue_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg)
1123 {
1124         dmu_tx_t *tx = arg;
1125         dsl_dataset_t *ds;
1126         int err;
1127         dsl_scan_t *scn = dp->dp_scan;
1128
1129         err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds);
1130         if (err)
1131                 return (err);
1132
1133         while (ds->ds_phys->ds_prev_snap_obj != 0) {
1134                 dsl_dataset_t *prev;
1135                 err = dsl_dataset_hold_obj(dp, ds->ds_phys->ds_prev_snap_obj,
1136                     FTAG, &prev);
1137                 if (err) {
1138                         dsl_dataset_rele(ds, FTAG);
1139                         return (err);
1140                 }
1141
1142                 /*
1143                  * If this is a clone, we don't need to worry about it for now.
1144                  */
1145                 if (prev->ds_phys->ds_next_snap_obj != ds->ds_object) {
1146                         dsl_dataset_rele(ds, FTAG);
1147                         dsl_dataset_rele(prev, FTAG);
1148                         return (0);
1149                 }
1150                 dsl_dataset_rele(ds, FTAG);
1151                 ds = prev;
1152         }
1153
1154         VERIFY(zap_add_int_key(dp->dp_meta_objset, scn->scn_phys.scn_queue_obj,
1155             ds->ds_object, ds->ds_phys->ds_prev_snap_txg, tx) == 0);
1156         dsl_dataset_rele(ds, FTAG);
1157         return (0);
1158 }
1159
1160 /*
1161  * Scrub/dedup interaction.
1162  *
1163  * If there are N references to a deduped block, we don't want to scrub it
1164  * N times -- ideally, we should scrub it exactly once.
1165  *
1166  * We leverage the fact that the dde's replication class (enum ddt_class)
1167  * is ordered from highest replication class (DDT_CLASS_DITTO) to lowest
1168  * (DDT_CLASS_UNIQUE) so that we may walk the DDT in that order.
1169  *
1170  * To prevent excess scrubbing, the scrub begins by walking the DDT
1171  * to find all blocks with refcnt > 1, and scrubs each of these once.
1172  * Since there are two replication classes which contain blocks with
1173  * refcnt > 1, we scrub the highest replication class (DDT_CLASS_DITTO) first.
1174  * Finally the top-down scrub begins, only visiting blocks with refcnt == 1.
1175  *
1176  * There would be nothing more to say if a block's refcnt couldn't change
1177  * during a scrub, but of course it can so we must account for changes
1178  * in a block's replication class.
1179  *
1180  * Here's an example of what can occur:
1181  *
1182  * If a block has refcnt > 1 during the DDT scrub phase, but has refcnt == 1
1183  * when visited during the top-down scrub phase, it will be scrubbed twice.
1184  * This negates our scrub optimization, but is otherwise harmless.
1185  *
1186  * If a block has refcnt == 1 during the DDT scrub phase, but has refcnt > 1
1187  * on each visit during the top-down scrub phase, it will never be scrubbed.
1188  * To catch this, ddt_sync_entry() notifies the scrub code whenever a block's
1189  * reference class transitions to a higher level (i.e DDT_CLASS_UNIQUE to
1190  * DDT_CLASS_DUPLICATE); if it transitions from refcnt == 1 to refcnt > 1
1191  * while a scrub is in progress, it scrubs the block right then.
1192  */
1193 static void
1194 dsl_scan_ddt(dsl_scan_t *scn, dmu_tx_t *tx)
1195 {
1196         ddt_bookmark_t *ddb = &scn->scn_phys.scn_ddt_bookmark;
1197         ddt_entry_t dde = { 0 };
1198         int error;
1199         uint64_t n = 0;
1200
1201         while ((error = ddt_walk(scn->scn_dp->dp_spa, ddb, &dde)) == 0) {
1202                 ddt_t *ddt;
1203
1204                 if (ddb->ddb_class > scn->scn_phys.scn_ddt_class_max)
1205                         break;
1206                 dprintf("visiting ddb=%llu/%llu/%llu/%llx\n",
1207                     (longlong_t)ddb->ddb_class,
1208                     (longlong_t)ddb->ddb_type,
1209                     (longlong_t)ddb->ddb_checksum,
1210                     (longlong_t)ddb->ddb_cursor);
1211
1212                 /* There should be no pending changes to the dedup table */
1213                 ddt = scn->scn_dp->dp_spa->spa_ddt[ddb->ddb_checksum];
1214                 ASSERT(avl_first(&ddt->ddt_tree) == NULL);
1215
1216                 dsl_scan_ddt_entry(scn, ddb->ddb_checksum, &dde, tx);
1217                 n++;
1218
1219                 if (dsl_scan_check_pause(scn, NULL))
1220                         break;
1221         }
1222
1223         zfs_dbgmsg("scanned %llu ddt entries with class_max = %u; pausing=%u",
1224             (longlong_t)n, (int)scn->scn_phys.scn_ddt_class_max,
1225             (int)scn->scn_pausing);
1226
1227         ASSERT(error == 0 || error == ENOENT);
1228         ASSERT(error != ENOENT ||
1229             ddb->ddb_class > scn->scn_phys.scn_ddt_class_max);
1230 }
1231
1232 /* ARGSUSED */
1233 void
1234 dsl_scan_ddt_entry(dsl_scan_t *scn, enum zio_checksum checksum,
1235     ddt_entry_t *dde, dmu_tx_t *tx)
1236 {
1237         const ddt_key_t *ddk = &dde->dde_key;
1238         ddt_phys_t *ddp = dde->dde_phys;
1239         blkptr_t bp;
1240         zbookmark_t zb = { 0 };
1241
1242         if (scn->scn_phys.scn_state != DSS_SCANNING)
1243                 return;
1244
1245         for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
1246                 if (ddp->ddp_phys_birth == 0 ||
1247                     ddp->ddp_phys_birth > scn->scn_phys.scn_cur_max_txg)
1248                         continue;
1249                 ddt_bp_create(checksum, ddk, ddp, &bp);
1250
1251                 scn->scn_visited_this_txg++;
1252                 scan_funcs[scn->scn_phys.scn_func](scn->scn_dp, &bp, &zb);
1253         }
1254 }
1255
1256 static void
1257 dsl_scan_visit(dsl_scan_t *scn, dmu_tx_t *tx)
1258 {
1259         dsl_pool_t *dp = scn->scn_dp;
1260         zap_cursor_t zc;
1261         zap_attribute_t za;
1262
1263         if (scn->scn_phys.scn_ddt_bookmark.ddb_class <=
1264             scn->scn_phys.scn_ddt_class_max) {
1265                 scn->scn_phys.scn_cur_min_txg = scn->scn_phys.scn_min_txg;
1266                 scn->scn_phys.scn_cur_max_txg = scn->scn_phys.scn_max_txg;
1267                 dsl_scan_ddt(scn, tx);
1268                 if (scn->scn_pausing)
1269                         return;
1270         }
1271
1272         if (scn->scn_phys.scn_bookmark.zb_objset == DMU_META_OBJSET) {
1273                 /* First do the MOS & ORIGIN */
1274
1275                 scn->scn_phys.scn_cur_min_txg = scn->scn_phys.scn_min_txg;
1276                 scn->scn_phys.scn_cur_max_txg = scn->scn_phys.scn_max_txg;
1277                 dsl_scan_visit_rootbp(scn, NULL,
1278                     &dp->dp_meta_rootbp, tx);
1279                 spa_set_rootblkptr(dp->dp_spa, &dp->dp_meta_rootbp);
1280                 if (scn->scn_pausing)
1281                         return;
1282
1283                 if (spa_version(dp->dp_spa) < SPA_VERSION_DSL_SCRUB) {
1284                         VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
1285                             enqueue_cb, tx, DS_FIND_CHILDREN));
1286                 } else {
1287                         dsl_scan_visitds(scn,
1288                             dp->dp_origin_snap->ds_object, tx);
1289                 }
1290                 ASSERT(!scn->scn_pausing);
1291         } else if (scn->scn_phys.scn_bookmark.zb_objset !=
1292             ZB_DESTROYED_OBJSET) {
1293                 /*
1294                  * If we were paused, continue from here.  Note if the
1295                  * ds we were paused on was deleted, the zb_objset may
1296                  * be -1, so we will skip this and find a new objset
1297                  * below.
1298                  */
1299                 dsl_scan_visitds(scn, scn->scn_phys.scn_bookmark.zb_objset, tx);
1300                 if (scn->scn_pausing)
1301                         return;
1302         }
1303
1304         /*
1305          * In case we were paused right at the end of the ds, zero the
1306          * bookmark so we don't think that we're still trying to resume.
1307          */
1308         bzero(&scn->scn_phys.scn_bookmark, sizeof (zbookmark_t));
1309
1310         /* keep pulling things out of the zap-object-as-queue */
1311         while (zap_cursor_init(&zc, dp->dp_meta_objset,
1312             scn->scn_phys.scn_queue_obj),
1313             zap_cursor_retrieve(&zc, &za) == 0) {
1314                 dsl_dataset_t *ds;
1315                 uint64_t dsobj;
1316
1317                 dsobj = strtonum(za.za_name, NULL);
1318                 VERIFY3U(0, ==, zap_remove_int(dp->dp_meta_objset,
1319                     scn->scn_phys.scn_queue_obj, dsobj, tx));
1320
1321                 /* Set up min/max txg */
1322                 VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
1323                 if (za.za_first_integer != 0) {
1324                         scn->scn_phys.scn_cur_min_txg =
1325                             MAX(scn->scn_phys.scn_min_txg,
1326                             za.za_first_integer);
1327                 } else {
1328                         scn->scn_phys.scn_cur_min_txg =
1329                             MAX(scn->scn_phys.scn_min_txg,
1330                             ds->ds_phys->ds_prev_snap_txg);
1331                 }
1332                 scn->scn_phys.scn_cur_max_txg = dsl_scan_ds_maxtxg(ds);
1333                 dsl_dataset_rele(ds, FTAG);
1334
1335                 dsl_scan_visitds(scn, dsobj, tx);
1336                 zap_cursor_fini(&zc);
1337                 if (scn->scn_pausing)
1338                         return;
1339         }
1340         zap_cursor_fini(&zc);
1341 }
1342
1343 static boolean_t
1344 dsl_scan_free_should_pause(dsl_scan_t *scn)
1345 {
1346         uint64_t elapsed_nanosecs;
1347
1348         elapsed_nanosecs = gethrtime() - scn->scn_sync_start_time;
1349         return (elapsed_nanosecs / NANOSEC > zfs_txg_timeout ||
1350             (elapsed_nanosecs / MICROSEC > zfs_free_min_time_ms &&
1351             txg_sync_waiting(scn->scn_dp)) ||
1352             spa_shutting_down(scn->scn_dp->dp_spa));
1353 }
1354
1355 static int
1356 dsl_scan_free_block_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
1357 {
1358         dsl_scan_t *scn = arg;
1359
1360         if (!scn->scn_is_bptree ||
1361             (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_OBJSET)) {
1362                 if (dsl_scan_free_should_pause(scn))
1363                         return (SET_ERROR(ERESTART));
1364         }
1365
1366         zio_nowait(zio_free_sync(scn->scn_zio_root, scn->scn_dp->dp_spa,
1367             dmu_tx_get_txg(tx), bp, 0));
1368         dsl_dir_diduse_space(tx->tx_pool->dp_free_dir, DD_USED_HEAD,
1369             -bp_get_dsize_sync(scn->scn_dp->dp_spa, bp),
1370             -BP_GET_PSIZE(bp), -BP_GET_UCSIZE(bp), tx);
1371         scn->scn_visited_this_txg++;
1372         return (0);
1373 }
1374
1375 boolean_t
1376 dsl_scan_active(dsl_scan_t *scn)
1377 {
1378         spa_t *spa = scn->scn_dp->dp_spa;
1379         uint64_t used = 0, comp, uncomp;
1380
1381         if (spa->spa_load_state != SPA_LOAD_NONE)
1382                 return (B_FALSE);
1383         if (spa_shutting_down(spa))
1384                 return (B_FALSE);
1385
1386         if (scn->scn_phys.scn_state == DSS_SCANNING ||
1387             scn->scn_async_destroying)
1388                 return (B_TRUE);
1389
1390         if (spa_version(scn->scn_dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
1391                 (void) bpobj_space(&scn->scn_dp->dp_free_bpobj,
1392                     &used, &comp, &uncomp);
1393         }
1394         return (used != 0);
1395 }
1396
1397 void
1398 dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t *tx)
1399 {
1400         dsl_scan_t *scn = dp->dp_scan;
1401         spa_t *spa = dp->dp_spa;
1402         int err;
1403
1404         /*
1405          * Check for scn_restart_txg before checking spa_load_state, so
1406          * that we can restart an old-style scan while the pool is being
1407          * imported (see dsl_scan_init).
1408          */
1409         if (scn->scn_restart_txg != 0 &&
1410             scn->scn_restart_txg <= tx->tx_txg) {
1411                 pool_scan_func_t func = POOL_SCAN_SCRUB;
1412                 dsl_scan_done(scn, B_FALSE, tx);
1413                 if (vdev_resilver_needed(spa->spa_root_vdev, NULL, NULL))
1414                         func = POOL_SCAN_RESILVER;
1415                 zfs_dbgmsg("restarting scan func=%u txg=%llu",
1416                     func, tx->tx_txg);
1417                 dsl_scan_setup_sync(&func, tx);
1418         }
1419
1420         if (!dsl_scan_active(scn) ||
1421             spa_sync_pass(dp->dp_spa) > 1)
1422                 return;
1423
1424         scn->scn_visited_this_txg = 0;
1425         scn->scn_pausing = B_FALSE;
1426         scn->scn_sync_start_time = gethrtime();
1427         spa->spa_scrub_active = B_TRUE;
1428
1429         /*
1430          * First process the free list.  If we pause the free, don't do
1431          * any scanning.  This ensures that there is no free list when
1432          * we are scanning, so the scan code doesn't have to worry about
1433          * traversing it.
1434          */
1435         if (spa_version(dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
1436                 scn->scn_is_bptree = B_FALSE;
1437                 scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
1438                     NULL, ZIO_FLAG_MUSTSUCCEED);
1439                 err = bpobj_iterate(&dp->dp_free_bpobj,
1440                     dsl_scan_free_block_cb, scn, tx);
1441                 VERIFY3U(0, ==, zio_wait(scn->scn_zio_root));
1442
1443                 if (err == 0 && spa_feature_is_active(spa,
1444                     &spa_feature_table[SPA_FEATURE_ASYNC_DESTROY])) {
1445                         ASSERT(scn->scn_async_destroying);
1446                         scn->scn_is_bptree = B_TRUE;
1447                         scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
1448                             NULL, ZIO_FLAG_MUSTSUCCEED);
1449                         err = bptree_iterate(dp->dp_meta_objset,
1450                             dp->dp_bptree_obj, B_TRUE, dsl_scan_free_block_cb,
1451                             scn, tx);
1452                         VERIFY0(zio_wait(scn->scn_zio_root));
1453
1454                         if (err == 0) {
1455                                 zfeature_info_t *feat = &spa_feature_table
1456                                     [SPA_FEATURE_ASYNC_DESTROY];
1457                                 /* finished; deactivate async destroy feature */
1458                                 spa_feature_decr(spa, feat, tx);
1459                                 ASSERT(!spa_feature_is_active(spa, feat));
1460                                 VERIFY0(zap_remove(dp->dp_meta_objset,
1461                                     DMU_POOL_DIRECTORY_OBJECT,
1462                                     DMU_POOL_BPTREE_OBJ, tx));
1463                                 VERIFY0(bptree_free(dp->dp_meta_objset,
1464                                     dp->dp_bptree_obj, tx));
1465                                 dp->dp_bptree_obj = 0;
1466                                 scn->scn_async_destroying = B_FALSE;
1467                         }
1468                 }
1469                 if (scn->scn_visited_this_txg) {
1470                         zfs_dbgmsg("freed %llu blocks in %llums from "
1471                             "free_bpobj/bptree txg %llu",
1472                             (longlong_t)scn->scn_visited_this_txg,
1473                             (longlong_t)
1474                             (gethrtime() - scn->scn_sync_start_time) / MICROSEC,
1475                             (longlong_t)tx->tx_txg);
1476                         scn->scn_visited_this_txg = 0;
1477                         /*
1478                          * Re-sync the ddt so that we can further modify
1479                          * it when doing bprewrite.
1480                          */
1481                         ddt_sync(spa, tx->tx_txg);
1482                 }
1483                 if (err == ERESTART)
1484                         return;
1485         }
1486
1487         if (scn->scn_phys.scn_state != DSS_SCANNING)
1488                 return;
1489
1490         if (scn->scn_phys.scn_ddt_bookmark.ddb_class <=
1491             scn->scn_phys.scn_ddt_class_max) {
1492                 zfs_dbgmsg("doing scan sync txg %llu; "
1493                     "ddt bm=%llu/%llu/%llu/%llx",
1494                     (longlong_t)tx->tx_txg,
1495                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_class,
1496                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_type,
1497                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_checksum,
1498                     (longlong_t)scn->scn_phys.scn_ddt_bookmark.ddb_cursor);
1499                 ASSERT(scn->scn_phys.scn_bookmark.zb_objset == 0);
1500                 ASSERT(scn->scn_phys.scn_bookmark.zb_object == 0);
1501                 ASSERT(scn->scn_phys.scn_bookmark.zb_level == 0);
1502                 ASSERT(scn->scn_phys.scn_bookmark.zb_blkid == 0);
1503         } else {
1504                 zfs_dbgmsg("doing scan sync txg %llu; bm=%llu/%llu/%llu/%llu",
1505                     (longlong_t)tx->tx_txg,
1506                     (longlong_t)scn->scn_phys.scn_bookmark.zb_objset,
1507                     (longlong_t)scn->scn_phys.scn_bookmark.zb_object,
1508                     (longlong_t)scn->scn_phys.scn_bookmark.zb_level,
1509                     (longlong_t)scn->scn_phys.scn_bookmark.zb_blkid);
1510         }
1511
1512         scn->scn_zio_root = zio_root(dp->dp_spa, NULL,
1513             NULL, ZIO_FLAG_CANFAIL);
1514         dsl_pool_config_enter(dp, FTAG);
1515         dsl_scan_visit(scn, tx);
1516         dsl_pool_config_exit(dp, FTAG);
1517         (void) zio_wait(scn->scn_zio_root);
1518         scn->scn_zio_root = NULL;
1519
1520         zfs_dbgmsg("visited %llu blocks in %llums",
1521             (longlong_t)scn->scn_visited_this_txg,
1522             (longlong_t)(gethrtime() - scn->scn_sync_start_time) / MICROSEC);
1523
1524         if (!scn->scn_pausing) {
1525                 /* finished with scan. */
1526                 zfs_dbgmsg("finished scan txg %llu", (longlong_t)tx->tx_txg);
1527                 dsl_scan_done(scn, B_TRUE, tx);
1528         }
1529
1530         if (DSL_SCAN_IS_SCRUB_RESILVER(scn)) {
1531                 mutex_enter(&spa->spa_scrub_lock);
1532                 while (spa->spa_scrub_inflight > 0) {
1533                         cv_wait(&spa->spa_scrub_io_cv,
1534                             &spa->spa_scrub_lock);
1535                 }
1536                 mutex_exit(&spa->spa_scrub_lock);
1537         }
1538
1539         dsl_scan_sync_state(scn, tx);
1540 }
1541
1542 /*
1543  * This will start a new scan, or restart an existing one.
1544  */
1545 void
1546 dsl_resilver_restart(dsl_pool_t *dp, uint64_t txg)
1547 {
1548         if (txg == 0) {
1549                 dmu_tx_t *tx;
1550                 tx = dmu_tx_create_dd(dp->dp_mos_dir);
1551                 VERIFY(0 == dmu_tx_assign(tx, TXG_WAIT));
1552
1553                 txg = dmu_tx_get_txg(tx);
1554                 dp->dp_scan->scn_restart_txg = txg;
1555                 dmu_tx_commit(tx);
1556         } else {
1557                 dp->dp_scan->scn_restart_txg = txg;
1558         }
1559         zfs_dbgmsg("restarting resilver txg=%llu", txg);
1560 }
1561
1562 boolean_t
1563 dsl_scan_resilvering(dsl_pool_t *dp)
1564 {
1565         return (dp->dp_scan->scn_phys.scn_state == DSS_SCANNING &&
1566             dp->dp_scan->scn_phys.scn_func == POOL_SCAN_RESILVER);
1567 }
1568
1569 /*
1570  * scrub consumers
1571  */
1572
1573 static void
1574 count_block(zfs_all_blkstats_t *zab, const blkptr_t *bp)
1575 {
1576         int i;
1577
1578         /*
1579          * If we resume after a reboot, zab will be NULL; don't record
1580          * incomplete stats in that case.
1581          */
1582         if (zab == NULL)
1583                 return;
1584
1585         for (i = 0; i < 4; i++) {
1586                 int l = (i < 2) ? BP_GET_LEVEL(bp) : DN_MAX_LEVELS;
1587                 int t = (i & 1) ? BP_GET_TYPE(bp) : DMU_OT_TOTAL;
1588                 if (t & DMU_OT_NEWTYPE)
1589                         t = DMU_OT_OTHER;
1590                 zfs_blkstat_t *zb = &zab->zab_type[l][t];
1591                 int equal;
1592
1593                 zb->zb_count++;
1594                 zb->zb_asize += BP_GET_ASIZE(bp);
1595                 zb->zb_lsize += BP_GET_LSIZE(bp);
1596                 zb->zb_psize += BP_GET_PSIZE(bp);
1597                 zb->zb_gangs += BP_COUNT_GANG(bp);
1598
1599                 switch (BP_GET_NDVAS(bp)) {
1600                 case 2:
1601                         if (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1602                             DVA_GET_VDEV(&bp->blk_dva[1]))
1603                                 zb->zb_ditto_2_of_2_samevdev++;
1604                         break;
1605                 case 3:
1606                         equal = (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1607                             DVA_GET_VDEV(&bp->blk_dva[1])) +
1608                             (DVA_GET_VDEV(&bp->blk_dva[0]) ==
1609                             DVA_GET_VDEV(&bp->blk_dva[2])) +
1610                             (DVA_GET_VDEV(&bp->blk_dva[1]) ==
1611                             DVA_GET_VDEV(&bp->blk_dva[2]));
1612                         if (equal == 1)
1613                                 zb->zb_ditto_2_of_3_samevdev++;
1614                         else if (equal == 3)
1615                                 zb->zb_ditto_3_of_3_samevdev++;
1616                         break;
1617                 }
1618         }
1619 }
1620
1621 static void
1622 dsl_scan_scrub_done(zio_t *zio)
1623 {
1624         spa_t *spa = zio->io_spa;
1625
1626         zio_data_buf_free(zio->io_data, zio->io_size);
1627
1628         mutex_enter(&spa->spa_scrub_lock);
1629         spa->spa_scrub_inflight--;
1630         cv_broadcast(&spa->spa_scrub_io_cv);
1631
1632         if (zio->io_error && (zio->io_error != ECKSUM ||
1633             !(zio->io_flags & ZIO_FLAG_SPECULATIVE))) {
1634                 spa->spa_dsl_pool->dp_scan->scn_phys.scn_errors++;
1635         }
1636         mutex_exit(&spa->spa_scrub_lock);
1637 }
1638
1639 static int
1640 dsl_scan_scrub_cb(dsl_pool_t *dp,
1641     const blkptr_t *bp, const zbookmark_t *zb)
1642 {
1643         dsl_scan_t *scn = dp->dp_scan;
1644         size_t size = BP_GET_PSIZE(bp);
1645         spa_t *spa = dp->dp_spa;
1646         uint64_t phys_birth = BP_PHYSICAL_BIRTH(bp);
1647         boolean_t needs_io;
1648         int zio_flags = ZIO_FLAG_SCAN_THREAD | ZIO_FLAG_RAW | ZIO_FLAG_CANFAIL;
1649         int zio_priority;
1650         unsigned int scan_delay = 0;
1651
1652         if (phys_birth <= scn->scn_phys.scn_min_txg ||
1653             phys_birth >= scn->scn_phys.scn_max_txg)
1654                 return (0);
1655
1656         count_block(dp->dp_blkstats, bp);
1657
1658         ASSERT(DSL_SCAN_IS_SCRUB_RESILVER(scn));
1659         if (scn->scn_phys.scn_func == POOL_SCAN_SCRUB) {
1660                 zio_flags |= ZIO_FLAG_SCRUB;
1661                 zio_priority = ZIO_PRIORITY_SCRUB;
1662                 needs_io = B_TRUE;
1663                 scan_delay = zfs_scrub_delay;
1664         } else {
1665                 ASSERT3U(scn->scn_phys.scn_func, ==, POOL_SCAN_RESILVER);
1666                 zio_flags |= ZIO_FLAG_RESILVER;
1667                 zio_priority = ZIO_PRIORITY_RESILVER;
1668                 needs_io = B_FALSE;
1669                 scan_delay = zfs_resilver_delay;
1670         }
1671
1672         /* If it's an intent log block, failure is expected. */
1673         if (zb->zb_level == ZB_ZIL_LEVEL)
1674                 zio_flags |= ZIO_FLAG_SPECULATIVE;
1675
1676         for (int d = 0; d < BP_GET_NDVAS(bp); d++) {
1677                 vdev_t *vd = vdev_lookup_top(spa,
1678                     DVA_GET_VDEV(&bp->blk_dva[d]));
1679
1680                 /*
1681                  * Keep track of how much data we've examined so that
1682                  * zpool(1M) status can make useful progress reports.
1683                  */
1684                 scn->scn_phys.scn_examined += DVA_GET_ASIZE(&bp->blk_dva[d]);
1685                 spa->spa_scan_pass_exam += DVA_GET_ASIZE(&bp->blk_dva[d]);
1686
1687                 /* if it's a resilver, this may not be in the target range */
1688                 if (!needs_io) {
1689                         if (DVA_GET_GANG(&bp->blk_dva[d])) {
1690                                 /*
1691                                  * Gang members may be spread across multiple
1692                                  * vdevs, so the best estimate we have is the
1693                                  * scrub range, which has already been checked.
1694                                  * XXX -- it would be better to change our
1695                                  * allocation policy to ensure that all
1696                                  * gang members reside on the same vdev.
1697                                  */
1698                                 needs_io = B_TRUE;
1699                         } else {
1700                                 needs_io = vdev_dtl_contains(vd, DTL_PARTIAL,
1701                                     phys_birth, 1);
1702                         }
1703                 }
1704         }
1705
1706         if (needs_io && !zfs_no_scrub_io) {
1707                 vdev_t *rvd = spa->spa_root_vdev;
1708                 uint64_t maxinflight = rvd->vdev_children *
1709                     MAX(zfs_top_maxinflight, 1);
1710                 void *data = zio_data_buf_alloc(size);
1711
1712                 mutex_enter(&spa->spa_scrub_lock);
1713                 while (spa->spa_scrub_inflight >= maxinflight)
1714                         cv_wait(&spa->spa_scrub_io_cv, &spa->spa_scrub_lock);
1715                 spa->spa_scrub_inflight++;
1716                 mutex_exit(&spa->spa_scrub_lock);
1717
1718                 /*
1719                  * If we're seeing recent (zfs_scan_idle) "important" I/Os
1720                  * then throttle our workload to limit the impact of a scan.
1721                  */
1722                 if (ddi_get_lbolt64() - spa->spa_last_io <= zfs_scan_idle)
1723                         delay(MAX((int)scan_delay, 0));
1724
1725                 zio_nowait(zio_read(NULL, spa, bp, data, size,
1726                     dsl_scan_scrub_done, NULL, zio_priority,
1727                     zio_flags, zb));
1728         }
1729
1730         /* do not relocate this block */
1731         return (0);
1732 }
1733
1734 int
1735 dsl_scan(dsl_pool_t *dp, pool_scan_func_t func)
1736 {
1737         spa_t *spa = dp->dp_spa;
1738
1739         /*
1740          * Purge all vdev caches and probe all devices.  We do this here
1741          * rather than in sync context because this requires a writer lock
1742          * on the spa_config lock, which we can't do from sync context.  The
1743          * spa_scrub_reopen flag indicates that vdev_open() should not
1744          * attempt to start another scrub.
1745          */
1746         spa_vdev_state_enter(spa, SCL_NONE);
1747         spa->spa_scrub_reopen = B_TRUE;
1748         vdev_reopen(spa->spa_root_vdev);
1749         spa->spa_scrub_reopen = B_FALSE;
1750         (void) spa_vdev_state_exit(spa, NULL, 0);
1751
1752         return (dsl_sync_task(spa_name(spa), dsl_scan_setup_check,
1753             dsl_scan_setup_sync, &func, 0));
1754 }