module/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) 2012 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
  40 int zfs_pd_blks_max = 100;
  41
  42 typedef struct prefetch_data {
  43         kmutex_t pd_mtx;
  44         kcondvar_t pd_cv;
  45         int pd_blks_max;
  46         int pd_blks_fetched;
  47         int pd_flags;
  48         boolean_t pd_cancel;
  49         boolean_t pd_exited;
  50 } prefetch_data_t;
  51
  52 typedef struct traverse_data {
  53         spa_t *td_spa;
  54         uint64_t td_objset;
  55         blkptr_t *td_rootbp;
  56         uint64_t td_min_txg;
  57         zbookmark_t *td_resume;
  58         int td_flags;
  59         prefetch_data_t *td_pfd;
  60         blkptr_cb_t *td_func;
  61         void *td_arg;
  62 } traverse_data_t;
  63
  64 static int traverse_dnode(traverse_data_t *td, const dnode_phys_t *dnp,
  65     arc_buf_t *buf, uint64_t objset, uint64_t object);
  66 static void prefetch_dnode_metadata(traverse_data_t *td, const dnode_phys_t *,
  67     arc_buf_t *buf, uint64_t objset, uint64_t object);
  68
  69 static int
  70 traverse_zil_block(zilog_t *zilog, blkptr_t *bp, void *arg, uint64_t claim_txg)
  71 {
  72         traverse_data_t *td = arg;
  73         zbookmark_t zb;
  74
  75         if (bp->blk_birth == 0)
  76                 return (0);
  77
  78         if (claim_txg == 0 && bp->blk_birth >= spa_first_txg(td->td_spa))
  79                 return (0);
  80
  81         SET_BOOKMARK(&zb, td->td_objset, ZB_ZIL_OBJECT, ZB_ZIL_LEVEL,
  82             bp->blk_cksum.zc_word[ZIL_ZC_SEQ]);
  83
  84         (void) td->td_func(td->td_spa, zilog, bp, NULL, &zb, NULL, td->td_arg);
  85
  86         return (0);
  87 }
  88
  89 static int
  90 traverse_zil_record(zilog_t *zilog, lr_t *lrc, void *arg, uint64_t claim_txg)
  91 {
  92         traverse_data_t *td = arg;
  93
  94         if (lrc->lrc_txtype == TX_WRITE) {
  95                 lr_write_t *lr = (lr_write_t *)lrc;
  96                 blkptr_t *bp = &lr->lr_blkptr;
  97                 zbookmark_t zb;
  98
  99                 if (bp->blk_birth == 0)
 100                         return (0);
 101
 102                 if (claim_txg == 0 || bp->blk_birth < claim_txg)
 103                         return (0);
 104
 105                 SET_BOOKMARK(&zb, td->td_objset, lr->lr_foid,
 106                     ZB_ZIL_LEVEL, lr->lr_offset / BP_GET_LSIZE(bp));
 107
 108                 (void) td->td_func(td->td_spa, zilog, bp, NULL, &zb, NULL,
 109                     td->td_arg);
 110         }
 111         return (0);
 112 }
 113
 114 static void
 115 traverse_zil(traverse_data_t *td, zil_header_t *zh)
 116 {
 117         uint64_t claim_txg = zh->zh_claim_txg;
 118         zilog_t *zilog;
 119
 120         /*
 121          * We only want to visit blocks that have been claimed but not yet
 122          * replayed; plus, in read-only mode, blocks that are already stable.
 123          */
 124         if (claim_txg == 0 && spa_writeable(td->td_spa))
 125                 return;
 126
 127         zilog = zil_alloc(spa_get_dsl(td->td_spa)->dp_meta_objset, zh);
 128
 129         (void) zil_parse(zilog, traverse_zil_block, traverse_zil_record, td,
 130             claim_txg);
 131
 132         zil_free(zilog);
 133 }
 134
 135 typedef enum resume_skip {
 136         RESUME_SKIP_ALL,
 137         RESUME_SKIP_NONE,
 138         RESUME_SKIP_CHILDREN
 139 } resume_skip_t;
 140
 141 /*
 142  * Returns RESUME_SKIP_ALL if td indicates that we are resuming a traversal and
 143  * the block indicated by zb does not need to be visited at all. Returns
 144  * RESUME_SKIP_CHILDREN if we are resuming a post traversal and we reach the
 145  * resume point. This indicates that this block should be visited but not its
 146  * children (since they must have been visited in a previous traversal).
 147  * Otherwise returns RESUME_SKIP_NONE.
 148  */
 149 static resume_skip_t
 150 resume_skip_check(traverse_data_t *td, const dnode_phys_t *dnp,
 151     const zbookmark_t *zb)
 152 {
 153         if (td->td_resume != NULL && !ZB_IS_ZERO(td->td_resume)) {
 154                 /*
 155                  * If we already visited this bp & everything below,
 156                  * don't bother doing it again.
 157                  */
 158                 if (zbookmark_is_before(dnp, zb, td->td_resume))
 159                         return (RESUME_SKIP_ALL);
 160
 161                 /*
 162                  * If we found the block we're trying to resume from, zero
 163                  * the bookmark out to indicate that we have resumed.
 164                  */
 165                 ASSERT3U(zb->zb_object, <=, td->td_resume->zb_object);
 166                 if (bcmp(zb, td->td_resume, sizeof (*zb)) == 0) {
 167                         bzero(td->td_resume, sizeof (*zb));
 168                         if (td->td_flags & TRAVERSE_POST)
 169                                 return (RESUME_SKIP_CHILDREN);
 170                 }
 171         }
 172         return (RESUME_SKIP_NONE);
 173 }
 174
 175 static void
 176 traverse_pause(traverse_data_t *td, const zbookmark_t *zb)
 177 {
 178         ASSERT(td->td_resume != NULL);
 179         ASSERT0(zb->zb_level);
 180         bcopy(zb, td->td_resume, sizeof (*td->td_resume));
 181 }
 182
 183 static void
 184 traverse_prefetch_metadata(traverse_data_t *td,
 185     arc_buf_t *pbuf, const blkptr_t *bp, const zbookmark_t *zb)
 186 {
 187         uint32_t flags = ARC_NOWAIT | ARC_PREFETCH;
 188
 189         if (!(td->td_flags & TRAVERSE_PREFETCH_METADATA))
 190                 return;
 191         /*
 192          * If we are in the process of resuming, don't prefetch, because
 193          * some children will not be needed (and in fact may have already
 194          * been freed).
 195          */
 196         if (td->td_resume != NULL && !ZB_IS_ZERO(td->td_resume))
 197                 return;
 198         if (BP_IS_HOLE(bp) || bp->blk_birth <= td->td_min_txg)
 199                 return;
 200         if (BP_GET_LEVEL(bp) == 0 && BP_GET_TYPE(bp) != DMU_OT_DNODE)
 201                 return;
 202
 203         (void) arc_read(NULL, td->td_spa, bp,
 204             pbuf, NULL, NULL, ZIO_PRIORITY_ASYNC_READ,
 205             ZIO_FLAG_CANFAIL, &flags, zb);
 206 }
 207
 208 static int
 209 traverse_visitbp(traverse_data_t *td, const dnode_phys_t *dnp,
 210     arc_buf_t *pbuf, 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_IS_HOLE(bp)) {
 231                 err = td->td_func(td->td_spa, NULL, NULL, pbuf, zb, dnp,
 232                     td->td_arg);
 233                 return (err);
 234         }
 235
 236         if (bp->blk_birth <= td->td_min_txg)
 237                 return (0);
 238
 239         if (pd && !pd->pd_exited &&
 240             ((pd->pd_flags & TRAVERSE_PREFETCH_DATA) ||
 241             BP_GET_TYPE(bp) == DMU_OT_DNODE || BP_GET_LEVEL(bp) > 0)) {
 242                 mutex_enter(&pd->pd_mtx);
 243                 ASSERT(pd->pd_blks_fetched >= 0);
 244                 while (pd->pd_blks_fetched == 0 && !pd->pd_exited)
 245                         cv_wait(&pd->pd_cv, &pd->pd_mtx);
 246                 pd->pd_blks_fetched--;
 247                 cv_broadcast(&pd->pd_cv);
 248                 mutex_exit(&pd->pd_mtx);
 249         }
 250
 251         if (td->td_flags & TRAVERSE_PRE) {
 252                 err = td->td_func(td->td_spa, NULL, bp, pbuf, zb, dnp,
 253                     td->td_arg);
 254                 if (err == TRAVERSE_VISIT_NO_CHILDREN)
 255                         return (0);
 256                 if (err == ERESTART)
 257                         pause = B_TRUE; /* handle pausing at a common point */
 258                 if (err != 0)
 259                         goto post;
 260         }
 261
 262         if (BP_GET_LEVEL(bp) > 0) {
 263                 uint32_t flags = ARC_WAIT;
 264                 int i;
 265                 blkptr_t *cbp;
 266                 int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT;
 267
 268                 err = dsl_read(NULL, td->td_spa, bp, pbuf,
 269                     arc_getbuf_func, &buf,
 270                     ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
 271                 if (err)
 272                         return (err);
 273                 cbp = buf->b_data;
 274
 275                 for (i = 0; i < epb; i++) {
 276                         SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
 277                             zb->zb_level - 1,
 278                             zb->zb_blkid * epb + i);
 279                         traverse_prefetch_metadata(td, buf, &cbp[i], &czb);
 280                 }
 281
 282                 /* recursively visitbp() blocks below this */
 283                 for (i = 0; i < epb; i++) {
 284                         SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
 285                             zb->zb_level - 1,
 286                             zb->zb_blkid * epb + i);
 287                         err = traverse_visitbp(td, dnp, buf, &cbp[i], &czb);
 288                         if (err) {
 289                                 if (!hard)
 290                                         break;
 291                                 lasterr = err;
 292                         }
 293                 }
 294         } else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) {
 295                 uint32_t flags = ARC_WAIT;
 296                 int i;
 297                 int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT;
 298
 299                 err = dsl_read(NULL, td->td_spa, bp, pbuf,
 300                     arc_getbuf_func, &buf,
 301                     ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
 302                 if (err)
 303                         return (err);
 304                 dnp = buf->b_data;
 305
 306                 for (i = 0; i < epb; i++) {
 307                         prefetch_dnode_metadata(td, &dnp[i], buf, zb->zb_objset,
 308                             zb->zb_blkid * epb + i);
 309                 }
 310
 311                 /* recursively visitbp() blocks below this */
 312                 for (i = 0; i < epb; i++) {
 313                         err = traverse_dnode(td, &dnp[i], buf, zb->zb_objset,
 314                             zb->zb_blkid * epb + i);
 315                         if (err) {
 316                                 if (!hard)
 317                                         break;
 318                                 lasterr = err;
 319                         }
 320                 }
 321         } else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) {
 322                 uint32_t flags = ARC_WAIT;
 323                 objset_phys_t *osp;
 324                 dnode_phys_t *dnp;
 325
 326                 err = dsl_read_nolock(NULL, td->td_spa, bp,
 327                     arc_getbuf_func, &buf,
 328                     ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
 329                 if (err)
 330                         return (err);
 331
 332                 osp = buf->b_data;
 333                 dnp = &osp->os_meta_dnode;
 334                 prefetch_dnode_metadata(td, dnp, buf, zb->zb_objset,
 335                     DMU_META_DNODE_OBJECT);
 336                 if (arc_buf_size(buf) >= sizeof (objset_phys_t)) {
 337                         prefetch_dnode_metadata(td, &osp->os_userused_dnode,
 338                             buf, zb->zb_objset, DMU_USERUSED_OBJECT);
 339                         prefetch_dnode_metadata(td, &osp->os_groupused_dnode,
 340                             buf, zb->zb_objset, DMU_USERUSED_OBJECT);
 341                 }
 342
 343                 err = traverse_dnode(td, dnp, buf, zb->zb_objset,
 344                     DMU_META_DNODE_OBJECT);
 345                 if (err && hard) {
 346                         lasterr = err;
 347                         err = 0;
 348                 }
 349                 if (err == 0 && arc_buf_size(buf) >= sizeof (objset_phys_t)) {
 350                         dnp = &osp->os_userused_dnode;
 351                         err = traverse_dnode(td, dnp, buf, zb->zb_objset,
 352                             DMU_USERUSED_OBJECT);
 353                 }
 354                 if (err && hard) {
 355                         lasterr = err;
 356                         err = 0;
 357                 }
 358                 if (err == 0 && arc_buf_size(buf) >= sizeof (objset_phys_t)) {
 359                         dnp = &osp->os_groupused_dnode;
 360                         err = traverse_dnode(td, dnp, buf, zb->zb_objset,
 361                             DMU_GROUPUSED_OBJECT);
 362                 }
 363         }
 364
 365         if (buf)
 366                 (void) arc_buf_remove_ref(buf, &buf);
 367
 368 post:
 369         if (err == 0 && lasterr == 0 && (td->td_flags & TRAVERSE_POST)) {
 370                 err = td->td_func(td->td_spa, NULL, bp, pbuf, zb, dnp,
 371                     td->td_arg);
 372                 if (err == ERESTART)
 373                         pause = B_TRUE;
 374         }
 375
 376         if (pause && td->td_resume != NULL) {
 377                 ASSERT3U(err, ==, ERESTART);
 378                 ASSERT(!hard);
 379                 traverse_pause(td, zb);
 380         }
 381
 382         return (err != 0 ? err : lasterr);
 383 }
 384
 385 static void
 386 prefetch_dnode_metadata(traverse_data_t *td, const dnode_phys_t *dnp,
 387     arc_buf_t *buf, uint64_t objset, uint64_t object)
 388 {
 389         int j;
 390         zbookmark_t czb;
 391
 392         for (j = 0; j < dnp->dn_nblkptr; j++) {
 393                 SET_BOOKMARK(&czb, objset, object, dnp->dn_nlevels - 1, j);
 394                 traverse_prefetch_metadata(td, buf, &dnp->dn_blkptr[j], &czb);
 395         }
 396
 397         if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
 398                 SET_BOOKMARK(&czb, objset, object, 0, DMU_SPILL_BLKID);
 399                 traverse_prefetch_metadata(td, buf, &dnp->dn_spill, &czb);
 400         }
 401 }
 402
 403 static int
 404 traverse_dnode(traverse_data_t *td, const dnode_phys_t *dnp,
 405     arc_buf_t *buf, uint64_t objset, uint64_t object)
 406 {
 407         int j, err = 0, lasterr = 0;
 408         zbookmark_t czb;
 409         boolean_t hard = (td->td_flags & TRAVERSE_HARD);
 410
 411         for (j = 0; j < dnp->dn_nblkptr; j++) {
 412                 SET_BOOKMARK(&czb, objset, object, dnp->dn_nlevels - 1, j);
 413                 err = traverse_visitbp(td, dnp, buf, &dnp->dn_blkptr[j], &czb);
 414                 if (err) {
 415                         if (!hard)
 416                                 break;
 417                         lasterr = err;
 418                 }
 419         }
 420
 421         if (dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
 422                 SET_BOOKMARK(&czb, objset, object, 0, DMU_SPILL_BLKID);
 423                 err = traverse_visitbp(td, dnp, buf, &dnp->dn_spill, &czb);
 424                 if (err) {
 425                         if (!hard)
 426                                 return (err);
 427                         lasterr = err;
 428                 }
 429         }
 430         return (err != 0 ? err : lasterr);
 431 }
 432
 433 /* ARGSUSED */
 434 static int
 435 traverse_prefetcher(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
 436     arc_buf_t *pbuf, const zbookmark_t *zb, const dnode_phys_t *dnp,
 437     void *arg)
 438 {
 439         prefetch_data_t *pfd = arg;
 440         uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH;
 441
 442         ASSERT(pfd->pd_blks_fetched >= 0);
 443         if (pfd->pd_cancel)
 444                 return (EINTR);
 445
 446         if (bp == NULL || !((pfd->pd_flags & TRAVERSE_PREFETCH_DATA) ||
 447             BP_GET_TYPE(bp) == DMU_OT_DNODE || BP_GET_LEVEL(bp) > 0) ||
 448             BP_GET_TYPE(bp) == DMU_OT_INTENT_LOG)
 449                 return (0);
 450
 451         mutex_enter(&pfd->pd_mtx);
 452         while (!pfd->pd_cancel && pfd->pd_blks_fetched >= pfd->pd_blks_max)
 453                 cv_wait(&pfd->pd_cv, &pfd->pd_mtx);
 454         pfd->pd_blks_fetched++;
 455         cv_broadcast(&pfd->pd_cv);
 456         mutex_exit(&pfd->pd_mtx);
 457
 458         (void) dsl_read(NULL, spa, bp, pbuf, NULL, NULL,
 459             ZIO_PRIORITY_ASYNC_READ,
 460             ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
 461             &aflags, zb);
 462
 463         return (0);
 464 }
 465
 466 static void
 467 traverse_prefetch_thread(void *arg)
 468 {
 469         traverse_data_t *td_main = arg;
 470         traverse_data_t td = *td_main;
 471         zbookmark_t czb;
 472
 473         td.td_func = traverse_prefetcher;
 474         td.td_arg = td_main->td_pfd;
 475         td.td_pfd = NULL;
 476
 477         SET_BOOKMARK(&czb, td.td_objset,
 478             ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
 479         (void) traverse_visitbp(&td, NULL, NULL, td.td_rootbp, &czb);
 480
 481         mutex_enter(&td_main->td_pfd->pd_mtx);
 482         td_main->td_pfd->pd_exited = B_TRUE;
 483         cv_broadcast(&td_main->td_pfd->pd_cv);
 484         mutex_exit(&td_main->td_pfd->pd_mtx);
 485 }
 486
 487 /*
 488  * NB: dataset must not be changing on-disk (eg, is a snapshot or we are
 489  * in syncing context).
 490  */
 491 static int
 492 traverse_impl(spa_t *spa, dsl_dataset_t *ds, uint64_t objset, blkptr_t *rootbp,
 493     uint64_t txg_start, zbookmark_t *resume, int flags,
 494     blkptr_cb_t func, void *arg)
 495 {
 496         traverse_data_t *td;
 497         prefetch_data_t *pd;
 498         zbookmark_t *czb;
 499         int err;
 500
 501         ASSERT(ds == NULL || objset == ds->ds_object);
 502         ASSERT(!(flags & TRAVERSE_PRE) || !(flags & TRAVERSE_POST));
 503
 504         /*
 505          * The data prefetching mechanism (the prefetch thread) is incompatible
 506          * with resuming from a bookmark.
 507          */
 508         ASSERT(resume == NULL || !(flags & TRAVERSE_PREFETCH_DATA));
 509
 510         td = kmem_alloc(sizeof(traverse_data_t), KM_PUSHPAGE);
 511         pd = kmem_zalloc(sizeof(prefetch_data_t), KM_PUSHPAGE);
 512         czb = kmem_alloc(sizeof(zbookmark_t), KM_PUSHPAGE);
 513
 514         td->td_spa = spa;
 515         td->td_objset = objset;
 516         td->td_rootbp = rootbp;
 517         td->td_min_txg = txg_start;
 518         td->td_resume = resume;
 519         td->td_func = func;
 520         td->td_arg = arg;
 521         td->td_pfd = pd;
 522         td->td_flags = flags;
 523
 524         pd->pd_blks_max = zfs_pd_blks_max;
 525         pd->pd_flags = flags;
 526         mutex_init(&pd->pd_mtx, NULL, MUTEX_DEFAULT, NULL);
 527         cv_init(&pd->pd_cv, NULL, CV_DEFAULT, NULL);
 528
 529         /* See comment on ZIL traversal in dsl_scan_visitds. */
 530         if (ds != NULL && !dsl_dataset_is_snapshot(ds)) {
 531                 objset_t *os;
 532
 533                 err = dmu_objset_from_ds(ds, &os);
 534                 if (err)
 535                         return (err);
 536
 537                 traverse_zil(td, &os->os_zil_header);
 538         }
 539
 540         if (!(flags & TRAVERSE_PREFETCH_DATA) ||
 541             0 == taskq_dispatch(system_taskq, traverse_prefetch_thread,
 542             td, TQ_NOQUEUE))
 543                 pd->pd_exited = B_TRUE;
 544
 545         SET_BOOKMARK(czb, td->td_objset,
 546             ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
 547         err = traverse_visitbp(td, NULL, NULL, rootbp, czb);
 548
 549         mutex_enter(&pd->pd_mtx);
 550         pd->pd_cancel = B_TRUE;
 551         cv_broadcast(&pd->pd_cv);
 552         while (!pd->pd_exited)
 553                 cv_wait(&pd->pd_cv, &pd->pd_mtx);
 554         mutex_exit(&pd->pd_mtx);
 555
 556         mutex_destroy(&pd->pd_mtx);
 557         cv_destroy(&pd->pd_cv);
 558
 559         kmem_free(czb, sizeof(zbookmark_t));
 560         kmem_free(pd, sizeof(struct prefetch_data));
 561         kmem_free(td, sizeof(struct traverse_data));
 562
 563         return (err);
 564 }
 565
 566 /*
 567  * NB: dataset must not be changing on-disk (eg, is a snapshot or we are
 568  * in syncing context).
 569  */
 570 int
 571 traverse_dataset(dsl_dataset_t *ds, uint64_t txg_start, int flags,
 572     blkptr_cb_t func, void *arg)
 573 {
 574         return (traverse_impl(ds->ds_dir->dd_pool->dp_spa, ds, ds->ds_object,
 575             &ds->ds_phys->ds_bp, txg_start, NULL, flags, func, arg));
 576 }
 577
 578 int
 579 traverse_dataset_destroyed(spa_t *spa, blkptr_t *blkptr,
 580     uint64_t txg_start, zbookmark_t *resume, int flags,
 581     blkptr_cb_t func, void *arg)
 582 {
 583         return (traverse_impl(spa, NULL, ZB_DESTROYED_OBJSET,
 584             blkptr, txg_start, resume, flags, func, arg));
 585 }
 586
 587 /*
 588  * NB: pool must not be changing on-disk (eg, from zdb or sync context).
 589  */
 590 int
 591 traverse_pool(spa_t *spa, uint64_t txg_start, int flags,
 592     blkptr_cb_t func, void *arg)
 593 {
 594         int err, lasterr = 0;
 595         uint64_t obj;
 596         dsl_pool_t *dp = spa_get_dsl(spa);
 597         objset_t *mos = dp->dp_meta_objset;
 598         boolean_t hard = (flags & TRAVERSE_HARD);
 599
 600         /* visit the MOS */
 601         err = traverse_impl(spa, NULL, 0, spa_get_rootblkptr(spa),
 602             txg_start, NULL, flags, func, arg);
 603         if (err)
 604                 return (err);
 605
 606         /* visit each dataset */
 607         for (obj = 1; err == 0 || (err != ESRCH && hard);
 608             err = dmu_object_next(mos, &obj, FALSE, txg_start)) {
 609                 dmu_object_info_t doi;
 610
 611                 err = dmu_object_info(mos, obj, &doi);
 612                 if (err) {
 613                         if (!hard)
 614                                 return (err);
 615                         lasterr = err;
 616                         continue;
 617                 }
 618
 619                 if (doi.doi_type == DMU_OT_DSL_DATASET) {
 620                         dsl_dataset_t *ds;
 621                         uint64_t txg = txg_start;
 622
 623                         rw_enter(&dp->dp_config_rwlock, RW_READER);
 624                         err = dsl_dataset_hold_obj(dp, obj, FTAG, &ds);
 625                         rw_exit(&dp->dp_config_rwlock);
 626                         if (err) {
 627                                 if (!hard)
 628                                         return (err);
 629                                 lasterr = err;
 630                                 continue;
 631                         }
 632                         if (ds->ds_phys->ds_prev_snap_txg > txg)
 633                                 txg = ds->ds_phys->ds_prev_snap_txg;
 634                         err = traverse_dataset(ds, txg, flags, func, arg);
 635                         dsl_dataset_rele(ds, FTAG);
 636                         if (err) {
 637                                 if (!hard)
 638                                         return (err);
 639                                 lasterr = err;
 640                         }
 641                 }
 642         }
 643         if (err == ESRCH)
 644                 err = 0;
 645         return (err != 0 ? err : lasterr);
 646 }
 647
 648 #if defined(_KERNEL) && defined(HAVE_SPL)
 649 EXPORT_SYMBOL(traverse_dataset);
 650 EXPORT_SYMBOL(traverse_pool);
 651
 652 module_param(zfs_pd_blks_max, int, 0644);
 653 MODULE_PARM_DESC(zfs_pd_blks_max, "Max number of blocks to prefetch");
 654 #endif