sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_destroy.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) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  23  * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
  24  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  25  * Copyright (c) 2013 by Joyent, Inc. All rights reserved.
  26  * Copyright (c) 2014 Integros [integros.com]
  27  */
  28
  29 #include <sys/zfs_context.h>
  30 #include <sys/dsl_userhold.h>
  31 #include <sys/dsl_dataset.h>
  32 #include <sys/dsl_synctask.h>
  33 #include <sys/dsl_destroy.h>
  34 #include <sys/dmu_tx.h>
  35 #include <sys/dsl_pool.h>
  36 #include <sys/dsl_dir.h>
  37 #include <sys/dmu_traverse.h>
  38 #include <sys/dsl_scan.h>
  39 #include <sys/dmu_objset.h>
  40 #include <sys/zap.h>
  41 #include <sys/zfeature.h>
  42 #include <sys/zfs_ioctl.h>
  43 #include <sys/dsl_deleg.h>
  44 #include <sys/dmu_impl.h>
  45 #include <sys/zcp.h>
  46 #if defined(__FreeBSD__) && defined(_KERNEL)
  47 #include <sys/zvol.h>
  48 #endif
  49
  50
  51 int
  52 dsl_destroy_snapshot_check_impl(dsl_dataset_t *ds, boolean_t defer)
  53 {
  54         if (!ds->ds_is_snapshot)
  55                 return (SET_ERROR(EINVAL));
  56
  57         if (dsl_dataset_long_held(ds))
  58                 return (SET_ERROR(EBUSY));
  59
  60         /*
  61          * Only allow deferred destroy on pools that support it.
  62          * NOTE: deferred destroy is only supported on snapshots.
  63          */
  64         if (defer) {
  65                 if (spa_version(ds->ds_dir->dd_pool->dp_spa) <
  66                     SPA_VERSION_USERREFS)
  67                         return (SET_ERROR(ENOTSUP));
  68                 return (0);
  69         }
  70
  71         /*
  72          * If this snapshot has an elevated user reference count,
  73          * we can't destroy it yet.
  74          */
  75         if (ds->ds_userrefs > 0)
  76                 return (SET_ERROR(EBUSY));
  77
  78         /*
  79          * Can't delete a branch point.
  80          */
  81         if (dsl_dataset_phys(ds)->ds_num_children > 1)
  82                 return (SET_ERROR(EEXIST));
  83
  84         return (0);
  85 }
  86
  87 int
  88 dsl_destroy_snapshot_check(void *arg, dmu_tx_t *tx)
  89 {
  90         dsl_destroy_snapshot_arg_t *ddsa = arg;
  91         const char *dsname = ddsa->ddsa_name;
  92         boolean_t defer = ddsa->ddsa_defer;
  93
  94         dsl_pool_t *dp = dmu_tx_pool(tx);
  95         int error = 0;
  96         dsl_dataset_t *ds;
  97
  98         error = dsl_dataset_hold(dp, dsname, FTAG, &ds);
  99
 100         /*
 101          * If the snapshot does not exist, silently ignore it, and
 102          * dsl_destroy_snapshot_sync() will be a no-op
 103          * (it's "already destroyed").
 104          */
 105         if (error == ENOENT)
 106                 return (0);
 107
 108         if (error == 0) {
 109                 error = dsl_destroy_snapshot_check_impl(ds, defer);
 110                 dsl_dataset_rele(ds, FTAG);
 111         }
 112
 113         return (error);
 114 }
 115
 116 struct process_old_arg {
 117         dsl_dataset_t *ds;
 118         dsl_dataset_t *ds_prev;
 119         boolean_t after_branch_point;
 120         zio_t *pio;
 121         uint64_t used, comp, uncomp;
 122 };
 123
 124 static int
 125 process_old_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
 126 {
 127         struct process_old_arg *poa = arg;
 128         dsl_pool_t *dp = poa->ds->ds_dir->dd_pool;
 129
 130         ASSERT(!BP_IS_HOLE(bp));
 131
 132         if (bp->blk_birth <= dsl_dataset_phys(poa->ds)->ds_prev_snap_txg) {
 133                 dsl_deadlist_insert(&poa->ds->ds_deadlist, bp, tx);
 134                 if (poa->ds_prev && !poa->after_branch_point &&
 135                     bp->blk_birth >
 136                     dsl_dataset_phys(poa->ds_prev)->ds_prev_snap_txg) {
 137                         dsl_dataset_phys(poa->ds_prev)->ds_unique_bytes +=
 138                             bp_get_dsize_sync(dp->dp_spa, bp);
 139                 }
 140         } else {
 141                 poa->used += bp_get_dsize_sync(dp->dp_spa, bp);
 142                 poa->comp += BP_GET_PSIZE(bp);
 143                 poa->uncomp += BP_GET_UCSIZE(bp);
 144                 dsl_free_sync(poa->pio, dp, tx->tx_txg, bp);
 145         }
 146         return (0);
 147 }
 148
 149 static void
 150 process_old_deadlist(dsl_dataset_t *ds, dsl_dataset_t *ds_prev,
 151     dsl_dataset_t *ds_next, boolean_t after_branch_point, dmu_tx_t *tx)
 152 {
 153         struct process_old_arg poa = { 0 };
 154         dsl_pool_t *dp = ds->ds_dir->dd_pool;
 155         objset_t *mos = dp->dp_meta_objset;
 156         uint64_t deadlist_obj;
 157
 158         ASSERT(ds->ds_deadlist.dl_oldfmt);
 159         ASSERT(ds_next->ds_deadlist.dl_oldfmt);
 160
 161         poa.ds = ds;
 162         poa.ds_prev = ds_prev;
 163         poa.after_branch_point = after_branch_point;
 164         poa.pio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
 165         VERIFY0(bpobj_iterate(&ds_next->ds_deadlist.dl_bpobj,
 166             process_old_cb, &poa, tx));
 167         VERIFY0(zio_wait(poa.pio));
 168         ASSERT3U(poa.used, ==, dsl_dataset_phys(ds)->ds_unique_bytes);
 169
 170         /* change snapused */
 171         dsl_dir_diduse_space(ds->ds_dir, DD_USED_SNAP,
 172             -poa.used, -poa.comp, -poa.uncomp, tx);
 173
 174         /* swap next's deadlist to our deadlist */
 175         dsl_deadlist_close(&ds->ds_deadlist);
 176         dsl_deadlist_close(&ds_next->ds_deadlist);
 177         deadlist_obj = dsl_dataset_phys(ds)->ds_deadlist_obj;
 178         dsl_dataset_phys(ds)->ds_deadlist_obj =
 179             dsl_dataset_phys(ds_next)->ds_deadlist_obj;
 180         dsl_dataset_phys(ds_next)->ds_deadlist_obj = deadlist_obj;
 181         dsl_deadlist_open(&ds->ds_deadlist, mos,
 182             dsl_dataset_phys(ds)->ds_deadlist_obj);
 183         dsl_deadlist_open(&ds_next->ds_deadlist, mos,
 184             dsl_dataset_phys(ds_next)->ds_deadlist_obj);
 185 }
 186
 187 static void
 188 dsl_dataset_remove_clones_key(dsl_dataset_t *ds, uint64_t mintxg, dmu_tx_t *tx)
 189 {
 190         objset_t *mos = ds->ds_dir->dd_pool->dp_meta_objset;
 191         zap_cursor_t zc;
 192         zap_attribute_t za;
 193
 194         /*
 195          * If it is the old version, dd_clones doesn't exist so we can't
 196          * find the clones, but dsl_deadlist_remove_key() is a no-op so it
 197          * doesn't matter.
 198          */
 199         if (dsl_dir_phys(ds->ds_dir)->dd_clones == 0)
 200                 return;
 201
 202         for (zap_cursor_init(&zc, mos, dsl_dir_phys(ds->ds_dir)->dd_clones);
 203             zap_cursor_retrieve(&zc, &za) == 0;
 204             zap_cursor_advance(&zc)) {
 205                 dsl_dataset_t *clone;
 206
 207                 VERIFY0(dsl_dataset_hold_obj(ds->ds_dir->dd_pool,
 208                     za.za_first_integer, FTAG, &clone));
 209                 if (clone->ds_dir->dd_origin_txg > mintxg) {
 210                         dsl_deadlist_remove_key(&clone->ds_deadlist,
 211                             mintxg, tx);
 212                         if (dsl_dataset_remap_deadlist_exists(clone)) {
 213                                 dsl_deadlist_remove_key(
 214                                     &clone->ds_remap_deadlist, mintxg, tx);
 215                         }
 216                         dsl_dataset_remove_clones_key(clone, mintxg, tx);
 217                 }
 218                 dsl_dataset_rele(clone, FTAG);
 219         }
 220         zap_cursor_fini(&zc);
 221 }
 222
 223 static void
 224 dsl_destroy_snapshot_handle_remaps(dsl_dataset_t *ds, dsl_dataset_t *ds_next,
 225     dmu_tx_t *tx)
 226 {
 227         dsl_pool_t *dp = ds->ds_dir->dd_pool;
 228
 229         /* Move blocks to be obsoleted to pool's obsolete list. */
 230         if (dsl_dataset_remap_deadlist_exists(ds_next)) {
 231                 if (!bpobj_is_open(&dp->dp_obsolete_bpobj))
 232                         dsl_pool_create_obsolete_bpobj(dp, tx);
 233
 234                 dsl_deadlist_move_bpobj(&ds_next->ds_remap_deadlist,
 235                     &dp->dp_obsolete_bpobj,
 236                     dsl_dataset_phys(ds)->ds_prev_snap_txg, tx);
 237         }
 238
 239         /* Merge our deadlist into next's and free it. */
 240         if (dsl_dataset_remap_deadlist_exists(ds)) {
 241                 uint64_t remap_deadlist_object =
 242                     dsl_dataset_get_remap_deadlist_object(ds);
 243                 ASSERT(remap_deadlist_object != 0);
 244
 245                 mutex_enter(&ds_next->ds_remap_deadlist_lock);
 246                 if (!dsl_dataset_remap_deadlist_exists(ds_next))
 247                         dsl_dataset_create_remap_deadlist(ds_next, tx);
 248                 mutex_exit(&ds_next->ds_remap_deadlist_lock);
 249
 250                 dsl_deadlist_merge(&ds_next->ds_remap_deadlist,
 251                     remap_deadlist_object, tx);
 252                 dsl_dataset_destroy_remap_deadlist(ds, tx);
 253         }
 254 }
 255
 256 void
 257 dsl_destroy_snapshot_sync_impl(dsl_dataset_t *ds, boolean_t defer, dmu_tx_t *tx)
 258 {
 259         int err;
 260         int after_branch_point = FALSE;
 261         dsl_pool_t *dp = ds->ds_dir->dd_pool;
 262         objset_t *mos = dp->dp_meta_objset;
 263         dsl_dataset_t *ds_prev = NULL;
 264         uint64_t obj;
 265
 266         ASSERT(RRW_WRITE_HELD(&dp->dp_config_rwlock));
 267         rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG);
 268         ASSERT3U(dsl_dataset_phys(ds)->ds_bp.blk_birth, <=, tx->tx_txg);
 269         rrw_exit(&ds->ds_bp_rwlock, FTAG);
 270         ASSERT(zfs_refcount_is_zero(&ds->ds_longholds));
 271
 272         if (defer &&
 273             (ds->ds_userrefs > 0 ||
 274             dsl_dataset_phys(ds)->ds_num_children > 1)) {
 275                 ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
 276                 dmu_buf_will_dirty(ds->ds_dbuf, tx);
 277                 dsl_dataset_phys(ds)->ds_flags |= DS_FLAG_DEFER_DESTROY;
 278                 spa_history_log_internal_ds(ds, "defer_destroy", tx, "");
 279                 return;
 280         }
 281
 282         ASSERT3U(dsl_dataset_phys(ds)->ds_num_children, <=, 1);
 283
 284         /* We need to log before removing it from the namespace. */
 285         spa_history_log_internal_ds(ds, "destroy", tx, "");
 286
 287         dsl_scan_ds_destroyed(ds, tx);
 288
 289         obj = ds->ds_object;
 290
 291         for (spa_feature_t f = 0; f < SPA_FEATURES; f++) {
 292                 if (ds->ds_feature_inuse[f]) {
 293                         dsl_dataset_deactivate_feature(obj, f, tx);
 294                         ds->ds_feature_inuse[f] = B_FALSE;
 295                 }
 296         }
 297         if (dsl_dataset_phys(ds)->ds_prev_snap_obj != 0) {
 298                 ASSERT3P(ds->ds_prev, ==, NULL);
 299                 VERIFY0(dsl_dataset_hold_obj(dp,
 300                     dsl_dataset_phys(ds)->ds_prev_snap_obj, FTAG, &ds_prev));
 301                 after_branch_point =
 302                     (dsl_dataset_phys(ds_prev)->ds_next_snap_obj != obj);
 303
 304                 dmu_buf_will_dirty(ds_prev->ds_dbuf, tx);
 305                 if (after_branch_point &&
 306                     dsl_dataset_phys(ds_prev)->ds_next_clones_obj != 0) {
 307                         dsl_dataset_remove_from_next_clones(ds_prev, obj, tx);
 308                         if (dsl_dataset_phys(ds)->ds_next_snap_obj != 0) {
 309                                 VERIFY0(zap_add_int(mos,
 310                                     dsl_dataset_phys(ds_prev)->
 311                                     ds_next_clones_obj,
 312                                     dsl_dataset_phys(ds)->ds_next_snap_obj,
 313                                     tx));
 314                         }
 315                 }
 316                 if (!after_branch_point) {
 317                         dsl_dataset_phys(ds_prev)->ds_next_snap_obj =
 318                             dsl_dataset_phys(ds)->ds_next_snap_obj;
 319                 }
 320         }
 321
 322         dsl_dataset_t *ds_next;
 323         uint64_t old_unique;
 324         uint64_t used = 0, comp = 0, uncomp = 0;
 325
 326         VERIFY0(dsl_dataset_hold_obj(dp,
 327             dsl_dataset_phys(ds)->ds_next_snap_obj, FTAG, &ds_next));
 328         ASSERT3U(dsl_dataset_phys(ds_next)->ds_prev_snap_obj, ==, obj);
 329
 330         old_unique = dsl_dataset_phys(ds_next)->ds_unique_bytes;
 331
 332         dmu_buf_will_dirty(ds_next->ds_dbuf, tx);
 333         dsl_dataset_phys(ds_next)->ds_prev_snap_obj =
 334             dsl_dataset_phys(ds)->ds_prev_snap_obj;
 335         dsl_dataset_phys(ds_next)->ds_prev_snap_txg =
 336             dsl_dataset_phys(ds)->ds_prev_snap_txg;
 337         ASSERT3U(dsl_dataset_phys(ds)->ds_prev_snap_txg, ==,
 338             ds_prev ? dsl_dataset_phys(ds_prev)->ds_creation_txg : 0);
 339
 340         if (ds_next->ds_deadlist.dl_oldfmt) {
 341                 process_old_deadlist(ds, ds_prev, ds_next,
 342                     after_branch_point, tx);
 343         } else {
 344                 /* Adjust prev's unique space. */
 345                 if (ds_prev && !after_branch_point) {
 346                         dsl_deadlist_space_range(&ds_next->ds_deadlist,
 347                             dsl_dataset_phys(ds_prev)->ds_prev_snap_txg,
 348                             dsl_dataset_phys(ds)->ds_prev_snap_txg,
 349                             &used, &comp, &uncomp);
 350                         dsl_dataset_phys(ds_prev)->ds_unique_bytes += used;
 351                 }
 352
 353                 /* Adjust snapused. */
 354                 dsl_deadlist_space_range(&ds_next->ds_deadlist,
 355                     dsl_dataset_phys(ds)->ds_prev_snap_txg, UINT64_MAX,
 356                     &used, &comp, &uncomp);
 357                 dsl_dir_diduse_space(ds->ds_dir, DD_USED_SNAP,
 358                     -used, -comp, -uncomp, tx);
 359
 360                 /* Move blocks to be freed to pool's free list. */
 361                 dsl_deadlist_move_bpobj(&ds_next->ds_deadlist,
 362                     &dp->dp_free_bpobj, dsl_dataset_phys(ds)->ds_prev_snap_txg,
 363                     tx);
 364                 dsl_dir_diduse_space(tx->tx_pool->dp_free_dir,
 365                     DD_USED_HEAD, used, comp, uncomp, tx);
 366
 367                 /* Merge our deadlist into next's and free it. */
 368                 dsl_deadlist_merge(&ds_next->ds_deadlist,
 369                     dsl_dataset_phys(ds)->ds_deadlist_obj, tx);
 370         }
 371
 372         dsl_deadlist_close(&ds->ds_deadlist);
 373         dsl_deadlist_free(mos, dsl_dataset_phys(ds)->ds_deadlist_obj, tx);
 374         dmu_buf_will_dirty(ds->ds_dbuf, tx);
 375         dsl_dataset_phys(ds)->ds_deadlist_obj = 0;
 376
 377         dsl_destroy_snapshot_handle_remaps(ds, ds_next, tx);
 378
 379         /* Collapse range in clone heads */
 380         dsl_dataset_remove_clones_key(ds,
 381             dsl_dataset_phys(ds)->ds_creation_txg, tx);
 382
 383         if (ds_next->ds_is_snapshot) {
 384                 dsl_dataset_t *ds_nextnext;
 385
 386                 /*
 387                  * Update next's unique to include blocks which
 388                  * were previously shared by only this snapshot
 389                  * and it.  Those blocks will be born after the
 390                  * prev snap and before this snap, and will have
 391                  * died after the next snap and before the one
 392                  * after that (ie. be on the snap after next's
 393                  * deadlist).
 394                  */
 395                 VERIFY0(dsl_dataset_hold_obj(dp,
 396                     dsl_dataset_phys(ds_next)->ds_next_snap_obj,
 397                     FTAG, &ds_nextnext));
 398                 dsl_deadlist_space_range(&ds_nextnext->ds_deadlist,
 399                     dsl_dataset_phys(ds)->ds_prev_snap_txg,
 400                     dsl_dataset_phys(ds)->ds_creation_txg,
 401                     &used, &comp, &uncomp);
 402                 dsl_dataset_phys(ds_next)->ds_unique_bytes += used;
 403                 dsl_dataset_rele(ds_nextnext, FTAG);
 404                 ASSERT3P(ds_next->ds_prev, ==, NULL);
 405
 406                 /* Collapse range in this head. */
 407                 dsl_dataset_t *hds;
 408                 VERIFY0(dsl_dataset_hold_obj(dp,
 409                     dsl_dir_phys(ds->ds_dir)->dd_head_dataset_obj, FTAG, &hds));
 410                 dsl_deadlist_remove_key(&hds->ds_deadlist,
 411                     dsl_dataset_phys(ds)->ds_creation_txg, tx);
 412                 if (dsl_dataset_remap_deadlist_exists(hds)) {
 413                         dsl_deadlist_remove_key(&hds->ds_remap_deadlist,
 414                             dsl_dataset_phys(ds)->ds_creation_txg, tx);
 415                 }
 416                 dsl_dataset_rele(hds, FTAG);
 417
 418         } else {
 419                 ASSERT3P(ds_next->ds_prev, ==, ds);
 420                 dsl_dataset_rele(ds_next->ds_prev, ds_next);
 421                 ds_next->ds_prev = NULL;
 422                 if (ds_prev) {
 423                         VERIFY0(dsl_dataset_hold_obj(dp,
 424                             dsl_dataset_phys(ds)->ds_prev_snap_obj,
 425                             ds_next, &ds_next->ds_prev));
 426                 }
 427
 428                 dsl_dataset_recalc_head_uniq(ds_next);
 429
 430                 /*
 431                  * Reduce the amount of our unconsumed refreservation
 432                  * being charged to our parent by the amount of
 433                  * new unique data we have gained.
 434                  */
 435                 if (old_unique < ds_next->ds_reserved) {
 436                         int64_t mrsdelta;
 437                         uint64_t new_unique =
 438                             dsl_dataset_phys(ds_next)->ds_unique_bytes;
 439
 440                         ASSERT(old_unique <= new_unique);
 441                         mrsdelta = MIN(new_unique - old_unique,
 442                             ds_next->ds_reserved - old_unique);
 443                         dsl_dir_diduse_space(ds->ds_dir,
 444                             DD_USED_REFRSRV, -mrsdelta, 0, 0, tx);
 445                 }
 446         }
 447         dsl_dataset_rele(ds_next, FTAG);
 448
 449         /*
 450          * This must be done after the dsl_traverse(), because it will
 451          * re-open the objset.
 452          */
 453         if (ds->ds_objset) {
 454                 dmu_objset_evict(ds->ds_objset);
 455                 ds->ds_objset = NULL;
 456         }
 457
 458         /* remove from snapshot namespace */
 459         dsl_dataset_t *ds_head;
 460         ASSERT(dsl_dataset_phys(ds)->ds_snapnames_zapobj == 0);
 461         VERIFY0(dsl_dataset_hold_obj(dp,
 462             dsl_dir_phys(ds->ds_dir)->dd_head_dataset_obj, FTAG, &ds_head));
 463         VERIFY0(dsl_dataset_get_snapname(ds));
 464 #ifdef ZFS_DEBUG
 465         {
 466                 uint64_t val;
 467
 468                 err = dsl_dataset_snap_lookup(ds_head,
 469                     ds->ds_snapname, &val);
 470                 ASSERT0(err);
 471                 ASSERT3U(val, ==, obj);
 472         }
 473 #endif
 474         VERIFY0(dsl_dataset_snap_remove(ds_head, ds->ds_snapname, tx, B_TRUE));
 475         dsl_dataset_rele(ds_head, FTAG);
 476
 477         if (ds_prev != NULL)
 478                 dsl_dataset_rele(ds_prev, FTAG);
 479
 480         spa_prop_clear_bootfs(dp->dp_spa, ds->ds_object, tx);
 481
 482         if (dsl_dataset_phys(ds)->ds_next_clones_obj != 0) {
 483                 uint64_t count;
 484                 ASSERT0(zap_count(mos,
 485                     dsl_dataset_phys(ds)->ds_next_clones_obj, &count) &&
 486                     count == 0);
 487                 VERIFY0(dmu_object_free(mos,
 488                     dsl_dataset_phys(ds)->ds_next_clones_obj, tx));
 489         }
 490         if (dsl_dataset_phys(ds)->ds_props_obj != 0)
 491                 VERIFY0(zap_destroy(mos, dsl_dataset_phys(ds)->ds_props_obj,
 492                     tx));
 493         if (dsl_dataset_phys(ds)->ds_userrefs_obj != 0)
 494                 VERIFY0(zap_destroy(mos, dsl_dataset_phys(ds)->ds_userrefs_obj,
 495                     tx));
 496
 497 #if defined(__FreeBSD__) && defined(_KERNEL)
 498         char dsname[ZFS_MAX_DATASET_NAME_LEN];
 499
 500         dsl_dataset_name(ds, dsname);
 501         zvol_remove_minors(dp->dp_spa, dsname);
 502 #endif
 503
 504         dsl_dir_rele(ds->ds_dir, ds);
 505         ds->ds_dir = NULL;
 506         dmu_object_free_zapified(mos, obj, tx);
 507 }
 508
 509 void
 510 dsl_destroy_snapshot_sync(void *arg, dmu_tx_t *tx)
 511 {
 512         dsl_destroy_snapshot_arg_t *ddsa = arg;
 513         const char *dsname = ddsa->ddsa_name;
 514         boolean_t defer = ddsa->ddsa_defer;
 515
 516         dsl_pool_t *dp = dmu_tx_pool(tx);
 517         dsl_dataset_t *ds;
 518
 519         int error = dsl_dataset_hold(dp, dsname, FTAG, &ds);
 520         if (error == ENOENT)
 521                 return;
 522         ASSERT0(error);
 523         dsl_destroy_snapshot_sync_impl(ds, defer, tx);
 524         dsl_dataset_rele(ds, FTAG);
 525 }
 526
 527 /*
 528  * The semantics of this function are described in the comment above
 529  * lzc_destroy_snaps().  To summarize:
 530  *
 531  * The snapshots must all be in the same pool.
 532  *
 533  * Snapshots that don't exist will be silently ignored (considered to be
 534  * "already deleted").
 535  *
 536  * On success, all snaps will be destroyed and this will return 0.
 537  * On failure, no snaps will be destroyed, the errlist will be filled in,
 538  * and this will return an errno.
 539  */
 540 int
 541 dsl_destroy_snapshots_nvl(nvlist_t *snaps, boolean_t defer,
 542     nvlist_t *errlist)
 543 {
 544         if (nvlist_next_nvpair(snaps, NULL) == NULL)
 545                 return (0);
 546
 547         /*
 548          * lzc_destroy_snaps() is documented to take an nvlist whose
 549          * values "don't matter".  We need to convert that nvlist to
 550          * one that we know can be converted to LUA. We also don't
 551          * care about any duplicate entries because the nvlist will
 552          * be converted to a LUA table which should take care of this.
 553          */
 554         nvlist_t *snaps_normalized;
 555         VERIFY0(nvlist_alloc(&snaps_normalized, 0, KM_SLEEP));
 556         for (nvpair_t *pair = nvlist_next_nvpair(snaps, NULL);
 557             pair != NULL; pair = nvlist_next_nvpair(snaps, pair)) {
 558                 fnvlist_add_boolean_value(snaps_normalized,
 559                     nvpair_name(pair), B_TRUE);
 560         }
 561
 562         nvlist_t *arg;
 563         VERIFY0(nvlist_alloc(&arg, 0, KM_SLEEP));
 564         fnvlist_add_nvlist(arg, "snaps", snaps_normalized);
 565         fnvlist_free(snaps_normalized);
 566         fnvlist_add_boolean_value(arg, "defer", defer);
 567
 568         nvlist_t *wrapper;
 569         VERIFY0(nvlist_alloc(&wrapper, 0, KM_SLEEP));
 570         fnvlist_add_nvlist(wrapper, ZCP_ARG_ARGLIST, arg);
 571         fnvlist_free(arg);
 572
 573         const char *program =
 574             "arg = ...\n"
 575             "snaps = arg['snaps']\n"
 576             "defer = arg['defer']\n"
 577             "errors = { }\n"
 578             "has_errors = false\n"
 579             "for snap, v in pairs(snaps) do\n"
 580             "    errno = zfs.check.destroy{snap, defer=defer}\n"
 581             "    zfs.debug('snap: ' .. snap .. ' errno: ' .. errno)\n"
 582             "    if errno == ENOENT then\n"
 583             "        snaps[snap] = nil\n"
 584             "    elseif errno ~= 0 then\n"
 585             "        errors[snap] = errno\n"
 586             "        has_errors = true\n"
 587             "    end\n"
 588             "end\n"
 589             "if has_errors then\n"
 590             "    return errors\n"
 591             "end\n"
 592             "for snap, v in pairs(snaps) do\n"
 593             "    errno = zfs.sync.destroy{snap, defer=defer}\n"
 594             "    assert(errno == 0)\n"
 595             "end\n"
 596             "return { }\n";
 597
 598         nvlist_t *result = fnvlist_alloc();
 599         int error = zcp_eval(nvpair_name(nvlist_next_nvpair(snaps, NULL)),
 600             program,
 601             B_TRUE,
 602             0,
 603             zfs_lua_max_memlimit,
 604             nvlist_next_nvpair(wrapper, NULL), result);
 605         if (error != 0) {
 606                 char *errorstr = NULL;
 607                 (void) nvlist_lookup_string(result, ZCP_RET_ERROR, &errorstr);
 608                 if (errorstr != NULL) {
 609                         zfs_dbgmsg(errorstr);
 610                 }
 611                 return (error);
 612         }
 613         fnvlist_free(wrapper);
 614
 615         /*
 616          * lzc_destroy_snaps() is documented to fill the errlist with
 617          * int32 values, so we need to covert the int64 values that are
 618          * returned from LUA.
 619          */
 620         int rv = 0;
 621         nvlist_t *errlist_raw = fnvlist_lookup_nvlist(result, ZCP_RET_RETURN);
 622         for (nvpair_t *pair = nvlist_next_nvpair(errlist_raw, NULL);
 623             pair != NULL; pair = nvlist_next_nvpair(errlist_raw, pair)) {
 624                 int32_t val = (int32_t)fnvpair_value_int64(pair);
 625                 if (rv == 0)
 626                         rv = val;
 627                 fnvlist_add_int32(errlist, nvpair_name(pair), val);
 628         }
 629         fnvlist_free(result);
 630         return (rv);
 631 }
 632
 633 int
 634 dsl_destroy_snapshot(const char *name, boolean_t defer)
 635 {
 636         int error;
 637         nvlist_t *nvl = fnvlist_alloc();
 638         nvlist_t *errlist = fnvlist_alloc();
 639
 640         fnvlist_add_boolean(nvl, name);
 641         error = dsl_destroy_snapshots_nvl(nvl, defer, errlist);
 642         fnvlist_free(errlist);
 643         fnvlist_free(nvl);
 644         return (error);
 645 }
 646
 647 struct killarg {
 648         dsl_dataset_t *ds;
 649         dmu_tx_t *tx;
 650 };
 651
 652 /* ARGSUSED */
 653 static int
 654 kill_blkptr(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
 655     const zbookmark_phys_t *zb, const dnode_phys_t *dnp, void *arg)
 656 {
 657         struct killarg *ka = arg;
 658         dmu_tx_t *tx = ka->tx;
 659
 660         if (bp == NULL || BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp))
 661                 return (0);
 662
 663         if (zb->zb_level == ZB_ZIL_LEVEL) {
 664                 ASSERT(zilog != NULL);
 665                 /*
 666                  * It's a block in the intent log.  It has no
 667                  * accounting, so just free it.
 668                  */
 669                 dsl_free(ka->tx->tx_pool, ka->tx->tx_txg, bp);
 670         } else {
 671                 ASSERT(zilog == NULL);
 672                 ASSERT3U(bp->blk_birth, >,
 673                     dsl_dataset_phys(ka->ds)->ds_prev_snap_txg);
 674                 (void) dsl_dataset_block_kill(ka->ds, bp, tx, B_FALSE);
 675         }
 676
 677         return (0);
 678 }
 679
 680 static void
 681 old_synchronous_dataset_destroy(dsl_dataset_t *ds, dmu_tx_t *tx)
 682 {
 683         struct killarg ka;
 684
 685         /*
 686          * Free everything that we point to (that's born after
 687          * the previous snapshot, if we are a clone)
 688          *
 689          * NB: this should be very quick, because we already
 690          * freed all the objects in open context.
 691          */
 692         ka.ds = ds;
 693         ka.tx = tx;
 694         VERIFY0(traverse_dataset(ds,
 695             dsl_dataset_phys(ds)->ds_prev_snap_txg, TRAVERSE_POST,
 696             kill_blkptr, &ka));
 697         ASSERT(!DS_UNIQUE_IS_ACCURATE(ds) ||
 698             dsl_dataset_phys(ds)->ds_unique_bytes == 0);
 699 }
 700
 701 int
 702 dsl_destroy_head_check_impl(dsl_dataset_t *ds, int expected_holds)
 703 {
 704         int error;
 705         uint64_t count;
 706         objset_t *mos;
 707
 708         ASSERT(!ds->ds_is_snapshot);
 709         if (ds->ds_is_snapshot)
 710                 return (SET_ERROR(EINVAL));
 711
 712         if (zfs_refcount_count(&ds->ds_longholds) != expected_holds)
 713                 return (SET_ERROR(EBUSY));
 714
 715         mos = ds->ds_dir->dd_pool->dp_meta_objset;
 716
 717         /*
 718          * Can't delete a head dataset if there are snapshots of it.
 719          * (Except if the only snapshots are from the branch we cloned
 720          * from.)
 721          */
 722         if (ds->ds_prev != NULL &&
 723             dsl_dataset_phys(ds->ds_prev)->ds_next_snap_obj == ds->ds_object)
 724                 return (SET_ERROR(EBUSY));
 725
 726         /*
 727          * Can't delete if there are children of this fs.
 728          */
 729         error = zap_count(mos,
 730             dsl_dir_phys(ds->ds_dir)->dd_child_dir_zapobj, &count);
 731         if (error != 0)
 732                 return (error);
 733         if (count != 0)
 734                 return (SET_ERROR(EEXIST));
 735
 736         if (dsl_dir_is_clone(ds->ds_dir) && DS_IS_DEFER_DESTROY(ds->ds_prev) &&
 737             dsl_dataset_phys(ds->ds_prev)->ds_num_children == 2 &&
 738             ds->ds_prev->ds_userrefs == 0) {
 739                 /* We need to remove the origin snapshot as well. */
 740                 if (!zfs_refcount_is_zero(&ds->ds_prev->ds_longholds))
 741                         return (SET_ERROR(EBUSY));
 742         }
 743         return (0);
 744 }
 745
 746 int
 747 dsl_destroy_head_check(void *arg, dmu_tx_t *tx)
 748 {
 749         dsl_destroy_head_arg_t *ddha = arg;
 750         dsl_pool_t *dp = dmu_tx_pool(tx);
 751         dsl_dataset_t *ds;
 752         int error;
 753
 754         error = dsl_dataset_hold(dp, ddha->ddha_name, FTAG, &ds);
 755         if (error != 0)
 756                 return (error);
 757
 758         error = dsl_destroy_head_check_impl(ds, 0);
 759         dsl_dataset_rele(ds, FTAG);
 760         return (error);
 761 }
 762
 763 static void
 764 dsl_dir_destroy_sync(uint64_t ddobj, dmu_tx_t *tx)
 765 {
 766         dsl_dir_t *dd;
 767         dsl_pool_t *dp = dmu_tx_pool(tx);
 768         objset_t *mos = dp->dp_meta_objset;
 769         dd_used_t t;
 770
 771         ASSERT(RRW_WRITE_HELD(&dmu_tx_pool(tx)->dp_config_rwlock));
 772
 773         VERIFY0(dsl_dir_hold_obj(dp, ddobj, NULL, FTAG, &dd));
 774
 775         ASSERT0(dsl_dir_phys(dd)->dd_head_dataset_obj);
 776
 777         /*
 778          * Decrement the filesystem count for all parent filesystems.
 779          *
 780          * When we receive an incremental stream into a filesystem that already
 781          * exists, a temporary clone is created.  We never count this temporary
 782          * clone, whose name begins with a '%'.
 783          */
 784         if (dd->dd_myname[0] != '%' && dd->dd_parent != NULL)
 785                 dsl_fs_ss_count_adjust(dd->dd_parent, -1,
 786                     DD_FIELD_FILESYSTEM_COUNT, tx);
 787
 788         /*
 789          * Remove our reservation. The impl() routine avoids setting the
 790          * actual property, which would require the (already destroyed) ds.
 791          */
 792         dsl_dir_set_reservation_sync_impl(dd, 0, tx);
 793
 794         ASSERT0(dsl_dir_phys(dd)->dd_used_bytes);
 795         ASSERT0(dsl_dir_phys(dd)->dd_reserved);
 796         for (t = 0; t < DD_USED_NUM; t++)
 797                 ASSERT0(dsl_dir_phys(dd)->dd_used_breakdown[t]);
 798
 799         VERIFY0(zap_destroy(mos, dsl_dir_phys(dd)->dd_child_dir_zapobj, tx));
 800         VERIFY0(zap_destroy(mos, dsl_dir_phys(dd)->dd_props_zapobj, tx));
 801         if (dsl_dir_phys(dd)->dd_clones != 0)
 802                 VERIFY0(zap_destroy(mos, dsl_dir_phys(dd)->dd_clones, tx));
 803         VERIFY0(dsl_deleg_destroy(mos, dsl_dir_phys(dd)->dd_deleg_zapobj, tx));
 804         VERIFY0(zap_remove(mos,
 805             dsl_dir_phys(dd->dd_parent)->dd_child_dir_zapobj,
 806             dd->dd_myname, tx));
 807
 808         dsl_dir_rele(dd, FTAG);
 809         dmu_object_free_zapified(mos, ddobj, tx);
 810 }
 811
 812 void
 813 dsl_destroy_head_sync_impl(dsl_dataset_t *ds, dmu_tx_t *tx)
 814 {
 815         dsl_pool_t *dp = dmu_tx_pool(tx);
 816         objset_t *mos = dp->dp_meta_objset;
 817         uint64_t obj, ddobj, prevobj = 0;
 818         boolean_t rmorigin;
 819
 820         ASSERT3U(dsl_dataset_phys(ds)->ds_num_children, <=, 1);
 821         ASSERT(ds->ds_prev == NULL ||
 822             dsl_dataset_phys(ds->ds_prev)->ds_next_snap_obj != ds->ds_object);
 823         rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG);
 824         ASSERT3U(dsl_dataset_phys(ds)->ds_bp.blk_birth, <=, tx->tx_txg);
 825         rrw_exit(&ds->ds_bp_rwlock, FTAG);
 826         ASSERT(RRW_WRITE_HELD(&dp->dp_config_rwlock));
 827
 828         /* We need to log before removing it from the namespace. */
 829         spa_history_log_internal_ds(ds, "destroy", tx, "");
 830
 831         rmorigin = (dsl_dir_is_clone(ds->ds_dir) &&
 832             DS_IS_DEFER_DESTROY(ds->ds_prev) &&
 833             dsl_dataset_phys(ds->ds_prev)->ds_num_children == 2 &&
 834             ds->ds_prev->ds_userrefs == 0);
 835
 836         /* Remove our reservation. */
 837         if (ds->ds_reserved != 0) {
 838                 dsl_dataset_set_refreservation_sync_impl(ds,
 839                     (ZPROP_SRC_NONE | ZPROP_SRC_LOCAL | ZPROP_SRC_RECEIVED),
 840                     0, tx);
 841                 ASSERT0(ds->ds_reserved);
 842         }
 843
 844         obj = ds->ds_object;
 845
 846         for (spa_feature_t f = 0; f < SPA_FEATURES; f++) {
 847                 if (ds->ds_feature_inuse[f]) {
 848                         dsl_dataset_deactivate_feature(obj, f, tx);
 849                         ds->ds_feature_inuse[f] = B_FALSE;
 850                 }
 851         }
 852
 853         dsl_scan_ds_destroyed(ds, tx);
 854
 855         if (dsl_dataset_phys(ds)->ds_prev_snap_obj != 0) {
 856                 /* This is a clone */
 857                 ASSERT(ds->ds_prev != NULL);
 858                 ASSERT3U(dsl_dataset_phys(ds->ds_prev)->ds_next_snap_obj, !=,
 859                     obj);
 860                 ASSERT0(dsl_dataset_phys(ds)->ds_next_snap_obj);
 861
 862                 dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
 863                 if (dsl_dataset_phys(ds->ds_prev)->ds_next_clones_obj != 0) {
 864                         dsl_dataset_remove_from_next_clones(ds->ds_prev,
 865                             obj, tx);
 866                 }
 867
 868                 ASSERT3U(dsl_dataset_phys(ds->ds_prev)->ds_num_children, >, 1);
 869                 dsl_dataset_phys(ds->ds_prev)->ds_num_children--;
 870         }
 871
 872         /*
 873          * Destroy the deadlist.  Unless it's a clone, the
 874          * deadlist should be empty since the dataset has no snapshots.
 875          * (If it's a clone, it's safe to ignore the deadlist contents
 876          * since they are still referenced by the origin snapshot.)
 877          */
 878         dsl_deadlist_close(&ds->ds_deadlist);
 879         dsl_deadlist_free(mos, dsl_dataset_phys(ds)->ds_deadlist_obj, tx);
 880         dmu_buf_will_dirty(ds->ds_dbuf, tx);
 881         dsl_dataset_phys(ds)->ds_deadlist_obj = 0;
 882
 883         if (dsl_dataset_remap_deadlist_exists(ds))
 884                 dsl_dataset_destroy_remap_deadlist(ds, tx);
 885
 886         objset_t *os;
 887         VERIFY0(dmu_objset_from_ds(ds, &os));
 888
 889         if (!spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_ASYNC_DESTROY)) {
 890                 old_synchronous_dataset_destroy(ds, tx);
 891         } else {
 892                 /*
 893                  * Move the bptree into the pool's list of trees to
 894                  * clean up and update space accounting information.
 895                  */
 896                 uint64_t used, comp, uncomp;
 897
 898                 zil_destroy_sync(dmu_objset_zil(os), tx);
 899
 900                 if (!spa_feature_is_active(dp->dp_spa,
 901                     SPA_FEATURE_ASYNC_DESTROY)) {
 902                         dsl_scan_t *scn = dp->dp_scan;
 903                         spa_feature_incr(dp->dp_spa, SPA_FEATURE_ASYNC_DESTROY,
 904                             tx);
 905                         dp->dp_bptree_obj = bptree_alloc(mos, tx);
 906                         VERIFY0(zap_add(mos,
 907                             DMU_POOL_DIRECTORY_OBJECT,
 908                             DMU_POOL_BPTREE_OBJ, sizeof (uint64_t), 1,
 909                             &dp->dp_bptree_obj, tx));
 910                         ASSERT(!scn->scn_async_destroying);
 911                         scn->scn_async_destroying = B_TRUE;
 912                 }
 913
 914                 used = dsl_dir_phys(ds->ds_dir)->dd_used_bytes;
 915                 comp = dsl_dir_phys(ds->ds_dir)->dd_compressed_bytes;
 916                 uncomp = dsl_dir_phys(ds->ds_dir)->dd_uncompressed_bytes;
 917
 918                 ASSERT(!DS_UNIQUE_IS_ACCURATE(ds) ||
 919                     dsl_dataset_phys(ds)->ds_unique_bytes == used);
 920
 921                 rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG);
 922                 bptree_add(mos, dp->dp_bptree_obj,
 923                     &dsl_dataset_phys(ds)->ds_bp,
 924                     dsl_dataset_phys(ds)->ds_prev_snap_txg,
 925                     used, comp, uncomp, tx);
 926                 rrw_exit(&ds->ds_bp_rwlock, FTAG);
 927                 dsl_dir_diduse_space(ds->ds_dir, DD_USED_HEAD,
 928                     -used, -comp, -uncomp, tx);
 929                 dsl_dir_diduse_space(dp->dp_free_dir, DD_USED_HEAD,
 930                     used, comp, uncomp, tx);
 931         }
 932
 933         if (ds->ds_prev != NULL) {
 934                 if (spa_version(dp->dp_spa) >= SPA_VERSION_DIR_CLONES) {
 935                         VERIFY0(zap_remove_int(mos,
 936                             dsl_dir_phys(ds->ds_prev->ds_dir)->dd_clones,
 937                             ds->ds_object, tx));
 938                 }
 939                 prevobj = ds->ds_prev->ds_object;
 940                 dsl_dataset_rele(ds->ds_prev, ds);
 941                 ds->ds_prev = NULL;
 942         }
 943
 944         /*
 945          * This must be done after the dsl_traverse(), because it will
 946          * re-open the objset.
 947          */
 948         if (ds->ds_objset) {
 949                 dmu_objset_evict(ds->ds_objset);
 950                 ds->ds_objset = NULL;
 951         }
 952
 953         /* Erase the link in the dir */
 954         dmu_buf_will_dirty(ds->ds_dir->dd_dbuf, tx);
 955         dsl_dir_phys(ds->ds_dir)->dd_head_dataset_obj = 0;
 956         ddobj = ds->ds_dir->dd_object;
 957         ASSERT(dsl_dataset_phys(ds)->ds_snapnames_zapobj != 0);
 958         VERIFY0(zap_destroy(mos,
 959             dsl_dataset_phys(ds)->ds_snapnames_zapobj, tx));
 960
 961         if (ds->ds_bookmarks != 0) {
 962                 VERIFY0(zap_destroy(mos, ds->ds_bookmarks, tx));
 963                 spa_feature_decr(dp->dp_spa, SPA_FEATURE_BOOKMARKS, tx);
 964         }
 965
 966         spa_prop_clear_bootfs(dp->dp_spa, ds->ds_object, tx);
 967
 968         ASSERT0(dsl_dataset_phys(ds)->ds_next_clones_obj);
 969         ASSERT0(dsl_dataset_phys(ds)->ds_props_obj);
 970         ASSERT0(dsl_dataset_phys(ds)->ds_userrefs_obj);
 971         dsl_dir_rele(ds->ds_dir, ds);
 972         ds->ds_dir = NULL;
 973         dmu_object_free_zapified(mos, obj, tx);
 974
 975         dsl_dir_destroy_sync(ddobj, tx);
 976
 977         if (rmorigin) {
 978                 dsl_dataset_t *prev;
 979                 VERIFY0(dsl_dataset_hold_obj(dp, prevobj, FTAG, &prev));
 980                 dsl_destroy_snapshot_sync_impl(prev, B_FALSE, tx);
 981                 dsl_dataset_rele(prev, FTAG);
 982         }
 983 }
 984
 985 void
 986 dsl_destroy_head_sync(void *arg, dmu_tx_t *tx)
 987 {
 988         dsl_destroy_head_arg_t *ddha = arg;
 989         dsl_pool_t *dp = dmu_tx_pool(tx);
 990         dsl_dataset_t *ds;
 991
 992         VERIFY0(dsl_dataset_hold(dp, ddha->ddha_name, FTAG, &ds));
 993         dsl_destroy_head_sync_impl(ds, tx);
 994 #if defined(__FreeBSD__) && defined(_KERNEL)
 995         zvol_remove_minors(dp->dp_spa, ddha->ddha_name);
 996 #endif
 997         dsl_dataset_rele(ds, FTAG);
 998 }
 999
1000 static void
1001 dsl_destroy_head_begin_sync(void *arg, dmu_tx_t *tx)
1002 {
1003         dsl_destroy_head_arg_t *ddha = arg;
1004         dsl_pool_t *dp = dmu_tx_pool(tx);
1005         dsl_dataset_t *ds;
1006
1007         VERIFY0(dsl_dataset_hold(dp, ddha->ddha_name, FTAG, &ds));
1008
1009         /* Mark it as inconsistent on-disk, in case we crash */
1010         dmu_buf_will_dirty(ds->ds_dbuf, tx);
1011         dsl_dataset_phys(ds)->ds_flags |= DS_FLAG_INCONSISTENT;
1012
1013         spa_history_log_internal_ds(ds, "destroy begin", tx, "");
1014         dsl_dataset_rele(ds, FTAG);
1015 }
1016
1017 int
1018 dsl_destroy_head(const char *name)
1019 {
1020         dsl_destroy_head_arg_t ddha;
1021         int error;
1022         spa_t *spa;
1023         boolean_t isenabled;
1024
1025 #ifdef _KERNEL
1026         zfs_destroy_unmount_origin(name);
1027 #endif
1028
1029         error = spa_open(name, &spa, FTAG);
1030         if (error != 0)
1031                 return (error);
1032         isenabled = spa_feature_is_enabled(spa, SPA_FEATURE_ASYNC_DESTROY);
1033         spa_close(spa, FTAG);
1034
1035         ddha.ddha_name = name;
1036
1037         if (!isenabled) {
1038                 objset_t *os;
1039
1040                 error = dsl_sync_task(name, dsl_destroy_head_check,
1041                     dsl_destroy_head_begin_sync, &ddha,
1042                     0, ZFS_SPACE_CHECK_DESTROY);
1043                 if (error != 0)
1044                         return (error);
1045
1046                 /*
1047                  * Head deletion is processed in one txg on old pools;
1048                  * remove the objects from open context so that the txg sync
1049                  * is not too long.
1050                  */
1051                 error = dmu_objset_own(name, DMU_OST_ANY, B_FALSE, FTAG, &os);
1052                 if (error == 0) {
1053                         uint64_t prev_snap_txg =
1054                             dsl_dataset_phys(dmu_objset_ds(os))->
1055                             ds_prev_snap_txg;
1056                         for (uint64_t obj = 0; error == 0;
1057                             error = dmu_object_next(os, &obj, FALSE,
1058                             prev_snap_txg))
1059                                 (void) dmu_free_long_object(os, obj);
1060                         /* sync out all frees */
1061                         txg_wait_synced(dmu_objset_pool(os), 0);
1062                         dmu_objset_disown(os, FTAG);
1063                 }
1064         }
1065
1066         return (dsl_sync_task(name, dsl_destroy_head_check,
1067             dsl_destroy_head_sync, &ddha, 0, ZFS_SPACE_CHECK_DESTROY));
1068 }
1069
1070 /*
1071  * Note, this function is used as the callback for dmu_objset_find().  We
1072  * always return 0 so that we will continue to find and process
1073  * inconsistent datasets, even if we encounter an error trying to
1074  * process one of them.
1075  */
1076 /* ARGSUSED */
1077 int
1078 dsl_destroy_inconsistent(const char *dsname, void *arg)
1079 {
1080         objset_t *os;
1081
1082         if (dmu_objset_hold(dsname, FTAG, &os) == 0) {
1083                 boolean_t need_destroy = DS_IS_INCONSISTENT(dmu_objset_ds(os));
1084
1085                 /*
1086                  * If the dataset is inconsistent because a resumable receive
1087                  * has failed, then do not destroy it.
1088                  */
1089                 if (dsl_dataset_has_resume_receive_state(dmu_objset_ds(os)))
1090                         need_destroy = B_FALSE;
1091
1092                 dmu_objset_rele(os, FTAG);
1093                 if (need_destroy)
1094                         (void) dsl_destroy_head(dsname);
1095         }
1096         return (0);
1097 }