usr/src/uts/common/fs/zfs/dmu_traverse.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) 2013 by Delphix. All rights reserved.
  24  */
  25
  26 #include <sys/zfs_context.h>
  27 #include <sys/dmu_objset.h>
  28 #include <sys/dmu_traverse.h>
  29 #include <sys/dsl_dataset.h>
  30 #include <sys/dsl_dir.h>
  31 #include <sys/dsl_pool.h>
  32 #include <sys/dnode.h>
  33 #include <sys/spa.h>
  34 #include <sys/zio.h>
  35 #include <sys/dmu_impl.h>
  36 #include <sys/sa.h>
  37 #include <sys/sa_impl.h>
  38 #include <sys/callb.h>
  39 #include <sys/zfeature.h>
  40
  41 int zfs_pd_blks_max = 100;
  42
  43 typedef struct prefetch_data {
  44         kmutex_t pd_mtx;
  45         kcondvar_t pd_cv;
  46         int pd_blks_max;
  47         int pd_blks_fetched;
  48         int pd_flags;
  49         boolean_t pd_cancel;
  50         boolean_t pd_exited;
  51 } prefetch_data_t;
  52
  53 typedef struct traverse_data {
  54         spa_t *td_spa;
  55         uint64_t td_objset;
  56         blkptr_t *td_rootbp;
  57         uint64_t td_min_txg;
  58         zbookmark_t *td_resume;
  59         int td_flags;
  60         prefetch_data_t *td_pfd;
  61         blkptr_cb_t *td_func;
  62         void *td_arg;
  63 } traverse_data_t;
  64
  65 static int traverse_dnode(traverse_data_t *td, const dnode_phys_t *dnp,
  66     uint64_t objset, uint64_t object);
  67 static void prefetch_dnode_metadata(traverse_data_t *td, const dnode_phys_t *,
  68     uint64_t objset, uint64_t object);
  69
  70 static int
  71 traverse_zil_block(zilog_t *zilog, blkptr_t *bp, void *arg, uint64_t claim_txg)
  72 {
  73         traverse_data_t *td = arg;
  74         zbookmark_t zb;
  75
  76         if (BP_IS_HOLE(bp))
  77                 return (0);
  78
  79         if (claim_txg == 0 && bp->blk_birth >= spa_first_txg(td->td_spa))
  80                 return (0);
  81
  82         SET_BOOKMARK(&zb, td->td_objset, ZB_ZIL_OBJECT, ZB_ZIL_LEVEL,
  83             bp->blk_cksum.zc_word[ZIL_ZC_SEQ]);
  84
  85         (void) td->td_func(td->td_spa, zilog, bp, &zb, NULL, td->td_arg);
  86
  87         return (0);
  88 }
  89
  90 static int
  91 traverse_zil_record(zilog_t *zilog, lr_t *lrc, void *arg, uint64_t claim_txg)
  92 {
  93         traverse_data_t *td = arg;
  94
  95         if (lrc->lrc_txtype == TX_WRITE) {
  96                 lr_write_t *lr = (lr_write_t *)lrc;
  97                 blkptr_t *bp = &lr->lr_blkptr;
  98                 zbookmark_t zb;
  99
 100                 if (BP_IS_HOLE(bp))
 101                         return (0);
 102
 103                 if (claim_txg == 0 || bp->blk_birth < claim_txg)
 104                         return (0);
 105
 106                 SET_BOOKMARK(&zb, td->td_objset, lr->lr_foid,
 107                     ZB_ZIL_LEVEL, lr->lr_offset / BP_GET_LSIZE(bp));
 108
 109                 (void) td->td_func(td->td_spa, zilog, bp, &zb, NULL,
 110                     td->td_arg);
 111         }
 112         return (0);
 113 }
 114
 115 static void
 116 traverse_zil(traverse_data_t *td, zil_header_t *zh)
 117 {
 118         uint64_t claim_txg = zh->zh_claim_txg;
 119         zilog_t *zilog;
 120
 121         /*
 122          * We only want to visit blocks that have been claimed but not yet
 123          * replayed; plus, in read-only mode, blocks that are already stable.
 124          */
 125         if (claim_txg == 0 && spa_writeable(td->td_spa))
 126                 return;
 127
 128         zilog = zil_alloc(spa_get_dsl(td->td_spa)->dp_meta_objset, zh);
 129
 130         (void) zil_parse(zilog, traverse_zil_block, traverse_zil_record, td,
 131             claim_txg);
 132
 133         zil_free(zilog);
 134 }
 135
 136 typedef enum resume_skip {
 137         RESUME_SKIP_ALL,
 138         RESUME_SKIP_NONE,
 139         RESUME_SKIP_CHILDREN
 140 } resume_skip_t;
 141
 142 /*
 143  * Returns RESUME_SKIP_ALL if td indicates that we are resuming a traversal and
 144  * the block indicated by zb does not need to be visited at all. Returns
 145  * RESUME_SKIP_CHILDREN if we are resuming a post traversal and we reach the
 146  * resume point. This indicates that this block should be visited but not its
 147  * children (since they must have been visited in a previous traversal).
 148  * Otherwise returns RESUME_SKIP_NONE.
 149  */
 150 static resume_skip_t
 151 resume_skip_check(traverse_data_t *td, const dnode_phys_t *dnp,
 152     const zbookmark_t *zb)
 153 {
 154         if (td->td_resume != NULL && !ZB_IS_ZERO(td->td_resume)) {
 155                 /*
 156                  * If we already visited this bp & everything below,
 157                  * don't bother doing it again.
 158                  */
 159                 if (zbookmark_is_before(dnp, zb, td->td_resume))
 160                         return (RESUME_SKIP_ALL);
 161
 162                 /*
 163                  * If we found the block we're trying to resume from, zero
 164                  * the bookmark out to indicate that we have resumed.
 165                  */
 166                 ASSERT3U(zb->zb_object, <=, td->td_resume->zb_object);
 167                 if (bcmp(zb, td->td_resume, sizeof (*zb)) == 0) {
 168                         bzero(td->td_resume, sizeof (*zb));
 169                         if (td->td_flags & TRAVERSE_POST)
 170                                 return (RESUME_SKIP_CHILDREN);
 171                 }
 172         }
 173         return (RESUME_SKIP_NONE);
 174 }
 175
 176 static void
 177 traverse_pause(traverse_data_t *td, const zbookmark_t *zb)
 178 {
 179         ASSERT(td->td_resume != NULL);
 180         ASSERT0(zb->zb_level);
 181         bcopy(zb, td->td_resume, sizeof (*td->td_resume));
 182 }
 183
 184 static void
 185 traverse_prefetch_metadata(traverse_data_t *td,
 186     const blkptr_t *bp, const zbookmark_t *zb)
 187 {
 188         uint32_t flags = ARC_NOWAIT | ARC_PREFETCH;
 189
 190         if (!(td->td_flags & TRAVERSE_PREFETCH_METADATA))
 191                 return;
 192         /*
 193          * If we are in the process of resuming, don't prefetch, because
 194          * some children will not be needed (and in fact may have already
 195          * been freed).
 196          */
 197         if (td->td_resume != NULL && !ZB_IS_ZERO(td->td_resume))
 198                 return;
 199         if (BP_IS_HOLE(bp) || bp->blk_birth <= td->td_min_txg)
 200                 return;
 201         if (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_DNODE)
 202                 return;
 203
 204         (void) arc_read(NULL, td->td_spa, bp, NULL, NULL,
 205             ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
 206 }
 207
 208 static int
 209 traverse_visitbp(traverse_data_t *td, const dnode_phys_t *dnp,
 210     const blkptr_t *bp, const zbookmark_t *zb)
 211 {
 212         zbookmark_t czb;
 213         int err = 0, lasterr = 0;
 214         arc_buf_t *buf = NULL;
 215         prefetch_data_t *pd = td->td_pfd;
 216         boolean_t hard = td->td_flags & TRAVERSE_HARD;
 217         boolean_t pause = B_FALSE;
 218
 219         switch (resume_skip_check(td, dnp, zb)) {
 220         case RESUME_SKIP_ALL:
 221                 return (0);
 222         case RESUME_SKIP_CHILDREN:
 223                 goto post;
 224         case RESUME_SKIP_NONE:
 225                 break;
 226         default:
 227                 ASSERT(0);
 228         }
 229
 230         if (bp->blk_birth == 0) {
 231                 if (spa_feature_is_active(td->td_spa, SPA_FEATURE_HOLE_BIRTH)) {
 232                         /*
 233                          * Since this block has a birth time of 0 it must be a
 234                          * hole created before the SPA_FEATURE_HOLE_BIRTH
 235                          * feature was enabled.  If SPA_FEATURE_HOLE_BIRTH
 236                          * was enabled before the min_txg for this traveral we
 237                          * know the hole must have been created before the
 238                          * min_txg for this traveral, so we can skip it. If
 239                          * SPA_FEATURE_HOLE_BIRTH was enabled after the min_txg
 240                          * for this traveral we cannot tell if the hole was
 241                          * created before or after the min_txg for this
 242                          * traversal, so we cannot skip it.
 243                          */
 244                         uint64_t hole_birth_enabled_txg;
 245                         VERIFY(spa_feature_enabled_txg(td->td_spa,
 246                             SPA_FEATURE_HOLE_BIRTH, &hole_birth_enabled_txg));
 247                         if (hole_birth_enabled_txg < td->td_min_txg)
 248                                 return (0);
 249                 }
 250         } else if (bp->blk_birth <= td->td_min_txg) {
 251                 return (0);
 252         }
 253
 254         if (BP_IS_HOLE(bp)) {
 255                 err = td->td_func(td->td_spa, NULL, bp, zb, dnp, td->td_arg);
 256                 return (err);
 257         }
 258
 259         if (pd && !pd->pd_exited &&
 260             ((pd->pd_flags & TRAVERSE_PREFETCH_DATA) ||
 261             BP_GET_TYPE(bp) == DMU_OT_DNODE || BP_GET_LEVEL(bp) > 0)) {
 262                 mutex_enter(&pd->pd_mtx);
 263                 ASSERT(pd->pd_blks_fetched >= 0);
 264                 while (pd->pd_blks_fetched == 0 && !pd->pd_exited)
 265                         cv_wait(&pd->pd_cv, &pd->pd_mtx);
 266                 pd->pd_blks_fetched--;
 267                 cv_broadcast(&pd->pd_cv);
 268                 mutex_exit(&pd->pd_mtx);
 269         }
 270
 271         if (td->td_flags & TRAVERSE_PRE) {
 272                 err = td->td_func(td->td_spa, NULL, bp, zb, dnp,
 273                     td->td_arg);
 274                 if (err == TRAVERSE_VISIT_NO_CHILDREN)
 275                         return (0);
 276                 if (err == ERESTART)
 277                         pause = B_TRUE; /* handle pausing at a common point */
 278                 if (err != 0)
 279                         goto post;
 280         }
 281
 282         if (BP_GET_LEVEL(bp) > 0) {
 283                 uint32_t flags = ARC_WAIT;
 284                 int i;
 285                 blkptr_t *cbp;
 286                 int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT;
 287
 288                 err = arc_read(NULL, td->td_spa, bp, arc_getbuf_func, &buf,
 289                     ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
 290                 if (err != 0)
 291                         return (err);
 292                 cbp = buf->b_data;
 293
 294                 for (i = 0; i < epb; i++) {
 295                         SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
 296                             zb->zb_level - 1,
 297                             zb->zb_blkid * epb + i);
 298                         traverse_prefetch_metadata(td, &cbp[i], &czb);
 299                 }
 300
 301                 /* recursively visitbp() blocks below this */
 302                 for (i = 0; i < epb; i++) {
 303                         SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
 304                             zb->zb_level - 1,
 305                             zb->zb_blkid * epb + i);
 306                         err = traverse_visitbp(td, dnp, &cbp[i], &czb);
 307                         if (err != 0) {
 308                                 if (!hard)
 309                                         break;
 310                                 lasterr = err;
 311                         }
 312                 }
 313         } else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) {
 314                 uint32_t flags = ARC_WAIT;
 315                 int i;
 316                 int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT;
 317
 318                 err = arc_read(NULL, td->td_spa, bp, arc_getbuf_func, &buf,
 319                     ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
 320                 if (err != 0)
 321                         return (err);
 322                 dnp = buf->b_data;
 323
 324                 for (i = 0; i < epb; i++) {
 325                         prefetch_dnode_metadata(td, &dnp[i], zb->zb_objset,
 326                             zb->zb_blkid * epb + i);
 327                 }
 328
 329                 /* recursively visitbp() blocks below this */
 330                 for (i = 0; i < epb; i++) {
 331                         err = traverse_dnode(td, &dnp[i], zb->zb_objset,
 332                             zb->zb_blkid * epb + i);
 333                         if (err != 0) {
 334                                 if (!hard)
 335                                         break;
 336                                 lasterr = err;
 337                         }
 338                 }
 339         } else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) {
 340                 uint32_t flags = ARC_WAIT;
 341                 objset_phys_t *osp;
 342                 dnode_phys_t *dnp;
 343
 344                 err = arc_read(NULL, td->td_spa, bp, arc_getbuf_func, &buf,
 345                     ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
 346                 if (err != 0)
 347                         return (err);
 348
 349                 osp = buf->b_data;
 350                 dnp = &osp->os_meta_dnode;
 351                 prefetch_dnode_metadata(td, dnp, zb->zb_objset,
 352                     DMU_META_DNODE_OBJECT);
 353                 if (arc_buf_size(buf) >= sizeof (objset_phys_t)) {
 354                         prefetch_dnode_metadata(td, &osp->os_groupused_dnode,
 355                             zb->zb_objset, DMU_GROUPUSED_OBJECT);
 356                         prefetch_dnode_metadata(td, &osp->os_userused_dnode,
 357                             zb->zb_objset, DMU_USERUSED_OBJECT);
 358                 }
 359
 360                 err = traverse_dnode(td, dnp, zb->zb_objset,
 361                     DMU_META_DNODE_OBJECT);
 362                 if (err && hard) {
 363                         lasterr = err;
 364                         err = 0;
 365                 }
 366                 if (err == 0 && arc_buf_size(buf) >= sizeof (objset_phys_t)) {
 367                         dnp = &osp->os_groupused_dnode;
 368                         err = traverse_dnode(td, dnp, zb->zb_objset,
 369                             DMU_GROUPUSED_OBJECT);
 370                 }
 371                 if (err && hard) {
 372                         lasterr = err;
 373                         err = 0;
 374                 }
 375                 if (err == 0 && arc_buf_size(buf) >= sizeof (objset_phys_t)) {
 376                         dnp = &osp->os_userused_dnode;
 377                         err = traverse_dnode(td, dnp, zb->zb_objset,
 378                             DMU_USERUSED_OBJECT);
 379                 }
 380         }
 381
 382         if (buf)
 383                 (void) arc_buf_remove_ref(buf, &buf);
 384
 385 post:
 386         if (err == 0 && (td->td_flags & TRAVERSE_POST)) {
 387                 err = td->td_func(td->td_spa, NULL, bp, zb, dnp, td->td_arg);
 388                 if (err == ERESTART)
 389                         pause = B_TRUE;
 390         }
 391
 392         if (pause && td->td_resume != NULL) {
 393                 ASSERT3U(err, ==, ERESTART);
 394                 ASSERT(!hard);
 395                 traverse_pause(td, zb);
 396         }
 397
 398         return (err != 0 ? err : lasterr);
 399 }
 400
 401 static void
 402 prefetch_dnode_metadata(traverse_data_t *td, const dnode_phys_t *dnp,
 403     uint64_t objset, uint64_t object)
 404 {
 405         int j;
 406         zbookmark_t czb;
 407
 408         for (j = 0; j < dnp->dn_nblkptr; j++) {
 409                 SET_BOOKMARK(&czb, objset, object, dnp->dn_nlevels - 1, j);
 410                 traverse_prefetch_metadata(td, &dnp->dn_blkptr[j], &czb);
 411         }
 412
 413         if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
 414                 SET_BOOKMARK(&czb, objset, object, 0, DMU_SPILL_BLKID);
 415                 traverse_prefetch_metadata(td, &dnp->dn_spill, &czb);
 416         }
 417 }
 418
 419 static int
 420 traverse_dnode(traverse_data_t *td, const dnode_phys_t *dnp,
 421     uint64_t objset, uint64_t object)
 422 {
 423         int j, err = 0, lasterr = 0;
 424         zbookmark_t czb;
 425         boolean_t hard = (td->td_flags & TRAVERSE_HARD);
 426
 427         for (j = 0; j < dnp->dn_nblkptr; j++) {
 428                 SET_BOOKMARK(&czb, objset, object, dnp->dn_nlevels - 1, j);
 429                 err = traverse_visitbp(td, dnp, &dnp->dn_blkptr[j], &czb);
 430                 if (err != 0) {
 431                         if (!hard)
 432                                 break;
 433                         lasterr = err;
 434                 }
 435         }
 436
 437         if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
 438                 SET_BOOKMARK(&czb, objset, object, 0, DMU_SPILL_BLKID);
 439                 err = traverse_visitbp(td, dnp, &dnp->dn_spill, &czb);
 440                 if (err != 0) {
 441                         if (!hard)
 442                                 return (err);
 443                         lasterr = err;
 444                 }
 445         }
 446         return (err != 0 ? err : lasterr);
 447 }
 448
 449 /* ARGSUSED */
 450 static int
 451 traverse_prefetcher(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
 452     const zbookmark_t *zb, const dnode_phys_t *dnp, void *arg)
 453 {
 454         prefetch_data_t *pfd = arg;
 455         uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH;
 456
 457         ASSERT(pfd->pd_blks_fetched >= 0);
 458         if (pfd->pd_cancel)
 459                 return (SET_ERROR(EINTR));
 460
 461         if (BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp) ||
 462             !((pfd->pd_flags & TRAVERSE_PREFETCH_DATA) ||
 463             BP_GET_TYPE(bp) == DMU_OT_DNODE || BP_GET_LEVEL(bp) > 0) ||
 464             BP_GET_TYPE(bp) == DMU_OT_INTENT_LOG)
 465                 return (0);
 466
 467         mutex_enter(&pfd->pd_mtx);
 468         while (!pfd->pd_cancel && pfd->pd_blks_fetched >= pfd->pd_blks_max)
 469                 cv_wait(&pfd->pd_cv, &pfd->pd_mtx);
 470         pfd->pd_blks_fetched++;
 471         cv_broadcast(&pfd->pd_cv);
 472         mutex_exit(&pfd->pd_mtx);
 473
 474         (void) arc_read(NULL, spa, bp, NULL, NULL, ZIO_PRIORITY_ASYNC_READ,
 475             ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE, &aflags, zb);
 476
 477         return (0);
 478 }
 479
 480 static void
 481 traverse_prefetch_thread(void *arg)
 482 {
 483         traverse_data_t *td_main = arg;
 484         traverse_data_t td = *td_main;
 485         zbookmark_t czb;
 486
 487         td.td_func = traverse_prefetcher;
 488         td.td_arg = td_main->td_pfd;
 489         td.td_pfd = NULL;
 490
 491         SET_BOOKMARK(&czb, td.td_objset,
 492             ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
 493         (void) traverse_visitbp(&td, NULL, td.td_rootbp, &czb);
 494
 495         mutex_enter(&td_main->td_pfd->pd_mtx);
 496         td_main->td_pfd->pd_exited = B_TRUE;
 497         cv_broadcast(&td_main->td_pfd->pd_cv);
 498         mutex_exit(&td_main->td_pfd->pd_mtx);
 499 }
 500
 501 /*
 502  * NB: dataset must not be changing on-disk (eg, is a snapshot or we are
 503  * in syncing context).
 504  */
 505 static int
 506 traverse_impl(spa_t *spa, dsl_dataset_t *ds, uint64_t objset, blkptr_t *rootbp,
 507     uint64_t txg_start, zbookmark_t *resume, int flags,
 508     blkptr_cb_t func, void *arg)
 509 {
 510         traverse_data_t td;
 511         prefetch_data_t pd = { 0 };
 512         zbookmark_t czb;
 513         int err;
 514
 515         ASSERT(ds == NULL || objset == ds->ds_object);
 516         ASSERT(!(flags & TRAVERSE_PRE) || !(flags & TRAVERSE_POST));
 517
 518         /*
 519          * The data prefetching mechanism (the prefetch thread) is incompatible
 520          * with resuming from a bookmark.
 521          */
 522         ASSERT(resume == NULL || !(flags & TRAVERSE_PREFETCH_DATA));
 523
 524         td.td_spa = spa;
 525         td.td_objset = objset;
 526         td.td_rootbp = rootbp;
 527         td.td_min_txg = txg_start;
 528         td.td_resume = resume;
 529         td.td_func = func;
 530         td.td_arg = arg;
 531         td.td_pfd = &pd;
 532         td.td_flags = flags;
 533
 534         pd.pd_blks_max = zfs_pd_blks_max;
 535         pd.pd_flags = flags;
 536         mutex_init(&pd.pd_mtx, NULL, MUTEX_DEFAULT, NULL);
 537         cv_init(&pd.pd_cv, NULL, CV_DEFAULT, NULL);
 538
 539         /* See comment on ZIL traversal in dsl_scan_visitds. */
 540         if (ds != NULL && !dsl_dataset_is_snapshot(ds) && !BP_IS_HOLE(rootbp)) {
 541                 uint32_t flags = ARC_WAIT;
 542                 objset_phys_t *osp;
 543                 arc_buf_t *buf;
 544
 545                 err = arc_read(NULL, td.td_spa, rootbp,
 546                     arc_getbuf_func, &buf,
 547                     ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, NULL);
 548                 if (err != 0)
 549                         return (err);
 550
 551                 osp = buf->b_data;
 552                 traverse_zil(&td, &osp->os_zil_header);
 553                 (void) arc_buf_remove_ref(buf, &buf);
 554         }
 555
 556         if (!(flags & TRAVERSE_PREFETCH_DATA) ||
 557             0 == taskq_dispatch(system_taskq, traverse_prefetch_thread,
 558             &td, TQ_NOQUEUE))
 559                 pd.pd_exited = B_TRUE;
 560
 561         SET_BOOKMARK(&czb, td.td_objset,
 562             ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
 563         err = traverse_visitbp(&td, NULL, rootbp, &czb);
 564
 565         mutex_enter(&pd.pd_mtx);
 566         pd.pd_cancel = B_TRUE;
 567         cv_broadcast(&pd.pd_cv);
 568         while (!pd.pd_exited)
 569                 cv_wait(&pd.pd_cv, &pd.pd_mtx);
 570         mutex_exit(&pd.pd_mtx);
 571
 572         mutex_destroy(&pd.pd_mtx);
 573         cv_destroy(&pd.pd_cv);
 574
 575         return (err);
 576 }
 577
 578 /*
 579  * NB: dataset must not be changing on-disk (eg, is a snapshot or we are
 580  * in syncing context).
 581  */
 582 int
 583 traverse_dataset(dsl_dataset_t *ds, uint64_t txg_start, int flags,
 584     blkptr_cb_t func, void *arg)
 585 {
 586         return (traverse_impl(ds->ds_dir->dd_pool->dp_spa, ds, ds->ds_object,
 587             &ds->ds_phys->ds_bp, txg_start, NULL, flags, func, arg));
 588 }
 589
 590 int
 591 traverse_dataset_destroyed(spa_t *spa, blkptr_t *blkptr,
 592     uint64_t txg_start, zbookmark_t *resume, int flags,
 593     blkptr_cb_t func, void *arg)
 594 {
 595         return (traverse_impl(spa, NULL, ZB_DESTROYED_OBJSET,
 596             blkptr, txg_start, resume, flags, func, arg));
 597 }
 598
 599 /*
 600  * NB: pool must not be changing on-disk (eg, from zdb or sync context).
 601  */
 602 int
 603 traverse_pool(spa_t *spa, uint64_t txg_start, int flags,
 604     blkptr_cb_t func, void *arg)
 605 {
 606         int err, lasterr = 0;
 607         uint64_t obj;
 608         dsl_pool_t *dp = spa_get_dsl(spa);
 609         objset_t *mos = dp->dp_meta_objset;
 610         boolean_t hard = (flags & TRAVERSE_HARD);
 611
 612         /* visit the MOS */
 613         err = traverse_impl(spa, NULL, 0, spa_get_rootblkptr(spa),
 614             txg_start, NULL, flags, func, arg);
 615         if (err != 0)
 616                 return (err);
 617
 618         /* visit each dataset */
 619         for (obj = 1; err == 0 || (err != ESRCH && hard);
 620             err = dmu_object_next(mos, &obj, FALSE, txg_start)) {
 621                 dmu_object_info_t doi;
 622
 623                 err = dmu_object_info(mos, obj, &doi);
 624                 if (err != 0) {
 625                         if (!hard)
 626                                 return (err);
 627                         lasterr = err;
 628                         continue;
 629                 }
 630
 631                 if (doi.doi_bonus_type == DMU_OT_DSL_DATASET) {
 632                         dsl_dataset_t *ds;
 633                         uint64_t txg = txg_start;
 634
 635                         dsl_pool_config_enter(dp, FTAG);
 636                         err = dsl_dataset_hold_obj(dp, obj, FTAG, &ds);
 637                         dsl_pool_config_exit(dp, FTAG);
 638                         if (err != 0) {
 639                                 if (!hard)
 640                                         return (err);
 641                                 lasterr = err;
 642                                 continue;
 643                         }
 644                         if (ds->ds_phys->ds_prev_snap_txg > txg)
 645                                 txg = ds->ds_phys->ds_prev_snap_txg;
 646                         err = traverse_dataset(ds, txg, flags, func, arg);
 647                         dsl_dataset_rele(ds, FTAG);
 648                         if (err != 0) {
 649                                 if (!hard)
 650                                         return (err);
 651                                 lasterr = err;
 652                         }
 653                 }
 654         }
 655         if (err == ESRCH)
 656                 err = 0;
 657         return (err != 0 ? err : lasterr);
 658 }