module/zfs/dmu_object.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 https://opensource.org/licenses/CDDL-1.0.
  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, 2017 by Delphix. All rights reserved.
  24  * Copyright 2014 HybridCluster. All rights reserved.
  25  */
  26
  27 #include <sys/dbuf.h>
  28 #include <sys/dmu.h>
  29 #include <sys/dmu_impl.h>
  30 #include <sys/dmu_objset.h>
  31 #include <sys/dmu_tx.h>
  32 #include <sys/dnode.h>
  33 #include <sys/zap.h>
  34 #include <sys/zfeature.h>
  35 #include <sys/dsl_dataset.h>
  36
  37 /*
  38  * Each of the concurrent object allocators will grab
  39  * 2^dmu_object_alloc_chunk_shift dnode slots at a time.  The default is to
  40  * grab 128 slots, which is 4 blocks worth.  This was experimentally
  41  * determined to be the lowest value that eliminates the measurable effect
  42  * of lock contention from this code path.
  43  */
  44 uint_t dmu_object_alloc_chunk_shift = 7;
  45
  46 static uint64_t
  47 dmu_object_alloc_impl(objset_t *os, dmu_object_type_t ot, int blocksize,
  48     int indirect_blockshift, dmu_object_type_t bonustype, int bonuslen,
  49     int dnodesize, dnode_t **allocated_dnode, const void *tag, dmu_tx_t *tx)
  50 {
  51         uint64_t object;
  52         uint64_t L1_dnode_count = DNODES_PER_BLOCK <<
  53             (DMU_META_DNODE(os)->dn_indblkshift - SPA_BLKPTRSHIFT);
  54         dnode_t *dn = NULL;
  55         int dn_slots = dnodesize >> DNODE_SHIFT;
  56         boolean_t restarted = B_FALSE;
  57         uint64_t *cpuobj = NULL;
  58         uint_t dnodes_per_chunk = 1 << dmu_object_alloc_chunk_shift;
  59         int error;
  60
  61         cpuobj = &os->os_obj_next_percpu[CPU_SEQID_UNSTABLE %
  62             os->os_obj_next_percpu_len];
  63
  64         if (dn_slots == 0) {
  65                 dn_slots = DNODE_MIN_SLOTS;
  66         } else {
  67                 ASSERT3S(dn_slots, >=, DNODE_MIN_SLOTS);
  68                 ASSERT3S(dn_slots, <=, DNODE_MAX_SLOTS);
  69         }
  70
  71         /*
  72          * The "chunk" of dnodes that is assigned to a CPU-specific
  73          * allocator needs to be at least one block's worth, to avoid
  74          * lock contention on the dbuf.  It can be at most one L1 block's
  75          * worth, so that the "rescan after polishing off a L1's worth"
  76          * logic below will be sure to kick in.
  77          */
  78         if (dnodes_per_chunk < DNODES_PER_BLOCK)
  79                 dnodes_per_chunk = DNODES_PER_BLOCK;
  80         if (dnodes_per_chunk > L1_dnode_count)
  81                 dnodes_per_chunk = L1_dnode_count;
  82
  83         /*
  84          * The caller requested the dnode be returned as a performance
  85          * optimization in order to avoid releasing the hold only to
  86          * immediately reacquire it.  Since they caller is responsible
  87          * for releasing the hold they must provide the tag.
  88          */
  89         if (allocated_dnode != NULL) {
  90                 ASSERT3P(tag, !=, NULL);
  91         } else {
  92                 ASSERT3P(tag, ==, NULL);
  93                 tag = FTAG;
  94         }
  95
  96         object = *cpuobj;
  97         for (;;) {
  98                 /*
  99                  * If we finished a chunk of dnodes, get a new one from
 100                  * the global allocator.
 101                  */
 102                 if ((P2PHASE(object, dnodes_per_chunk) == 0) ||
 103                     (P2PHASE(object + dn_slots - 1, dnodes_per_chunk) <
 104                     dn_slots)) {
 105                         DNODE_STAT_BUMP(dnode_alloc_next_chunk);
 106                         mutex_enter(&os->os_obj_lock);
 107                         ASSERT0(P2PHASE(os->os_obj_next_chunk,
 108                             dnodes_per_chunk));
 109                         object = os->os_obj_next_chunk;
 110
 111                         /*
 112                          * Each time we polish off a L1 bp worth of dnodes
 113                          * (2^12 objects), move to another L1 bp that's
 114                          * still reasonably sparse (at most 1/4 full). Look
 115                          * from the beginning at most once per txg. If we
 116                          * still can't allocate from that L1 block, search
 117                          * for an empty L0 block, which will quickly skip
 118                          * to the end of the metadnode if no nearby L0
 119                          * blocks are empty. This fallback avoids a
 120                          * pathology where full dnode blocks containing
 121                          * large dnodes appear sparse because they have a
 122                          * low blk_fill, leading to many failed allocation
 123                          * attempts. In the long term a better mechanism to
 124                          * search for sparse metadnode regions, such as
 125                          * spacemaps, could be implemented.
 126                          *
 127                          * os_scan_dnodes is set during txg sync if enough
 128                          * objects have been freed since the previous
 129                          * rescan to justify backfilling again.
 130                          *
 131                          * Note that dmu_traverse depends on the behavior
 132                          * that we use multiple blocks of the dnode object
 133                          * before going back to reuse objects.  Any change
 134                          * to this algorithm should preserve that property
 135                          * or find another solution to the issues described
 136                          * in traverse_visitbp.
 137                          */
 138                         if (P2PHASE(object, L1_dnode_count) == 0) {
 139                                 uint64_t offset;
 140                                 uint64_t blkfill;
 141                                 int minlvl;
 142                                 if (os->os_rescan_dnodes) {
 143                                         offset = 0;
 144                                         os->os_rescan_dnodes = B_FALSE;
 145                                 } else {
 146                                         offset = object << DNODE_SHIFT;
 147                                 }
 148                                 blkfill = restarted ? 1 : DNODES_PER_BLOCK >> 2;
 149                                 minlvl = restarted ? 1 : 2;
 150                                 restarted = B_TRUE;
 151                                 error = dnode_next_offset(DMU_META_DNODE(os),
 152                                     DNODE_FIND_HOLE, &offset, minlvl,
 153                                     blkfill, 0);
 154                                 if (error == 0) {
 155                                         object = offset >> DNODE_SHIFT;
 156                                 }
 157                         }
 158                         /*
 159                          * Note: if "restarted", we may find a L0 that
 160                          * is not suitably aligned.
 161                          */
 162                         os->os_obj_next_chunk =
 163                             P2ALIGN(object, dnodes_per_chunk) +
 164                             dnodes_per_chunk;
 165                         (void) atomic_swap_64(cpuobj, object);
 166                         mutex_exit(&os->os_obj_lock);
 167                 }
 168
 169                 /*
 170                  * The value of (*cpuobj) before adding dn_slots is the object
 171                  * ID assigned to us.  The value afterwards is the object ID
 172                  * assigned to whoever wants to do an allocation next.
 173                  */
 174                 object = atomic_add_64_nv(cpuobj, dn_slots) - dn_slots;
 175
 176                 /*
 177                  * XXX We should check for an i/o error here and return
 178                  * up to our caller.  Actually we should pre-read it in
 179                  * dmu_tx_assign(), but there is currently no mechanism
 180                  * to do so.
 181                  */
 182                 error = dnode_hold_impl(os, object, DNODE_MUST_BE_FREE,
 183                     dn_slots, tag, &dn);
 184                 if (error == 0) {
 185                         rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
 186                         /*
 187                          * Another thread could have allocated it; check
 188                          * again now that we have the struct lock.
 189                          */
 190                         if (dn->dn_type == DMU_OT_NONE) {
 191                                 dnode_allocate(dn, ot, blocksize,
 192                                     indirect_blockshift, bonustype,
 193                                     bonuslen, dn_slots, tx);
 194                                 rw_exit(&dn->dn_struct_rwlock);
 195                                 dmu_tx_add_new_object(tx, dn);
 196
 197                                 /*
 198                                  * Caller requested the allocated dnode be
 199                                  * returned and is responsible for the hold.
 200                                  */
 201                                 if (allocated_dnode != NULL)
 202                                         *allocated_dnode = dn;
 203                                 else
 204                                         dnode_rele(dn, tag);
 205
 206                                 return (object);
 207                         }
 208                         rw_exit(&dn->dn_struct_rwlock);
 209                         dnode_rele(dn, tag);
 210                         DNODE_STAT_BUMP(dnode_alloc_race);
 211                 }
 212
 213                 /*
 214                  * Skip to next known valid starting point on error.  This
 215                  * is the start of the next block of dnodes.
 216                  */
 217                 if (dmu_object_next(os, &object, B_TRUE, 0) != 0) {
 218                         object = P2ROUNDUP(object + 1, DNODES_PER_BLOCK);
 219                         DNODE_STAT_BUMP(dnode_alloc_next_block);
 220                 }
 221                 (void) atomic_swap_64(cpuobj, object);
 222         }
 223 }
 224
 225 uint64_t
 226 dmu_object_alloc(objset_t *os, dmu_object_type_t ot, int blocksize,
 227     dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
 228 {
 229         return dmu_object_alloc_impl(os, ot, blocksize, 0, bonustype,
 230             bonuslen, 0, NULL, NULL, tx);
 231 }
 232
 233 uint64_t
 234 dmu_object_alloc_ibs(objset_t *os, dmu_object_type_t ot, int blocksize,
 235     int indirect_blockshift, dmu_object_type_t bonustype, int bonuslen,
 236     dmu_tx_t *tx)
 237 {
 238         return dmu_object_alloc_impl(os, ot, blocksize, indirect_blockshift,
 239             bonustype, bonuslen, 0, NULL, NULL, tx);
 240 }
 241
 242 uint64_t
 243 dmu_object_alloc_dnsize(objset_t *os, dmu_object_type_t ot, int blocksize,
 244     dmu_object_type_t bonustype, int bonuslen, int dnodesize, dmu_tx_t *tx)
 245 {
 246         return (dmu_object_alloc_impl(os, ot, blocksize, 0, bonustype,
 247             bonuslen, dnodesize, NULL, NULL, tx));
 248 }
 249
 250 /*
 251  * Allocate a new object and return a pointer to the newly allocated dnode
 252  * via the allocated_dnode argument.  The returned dnode will be held and
 253  * the caller is responsible for releasing the hold by calling dnode_rele().
 254  */
 255 uint64_t
 256 dmu_object_alloc_hold(objset_t *os, dmu_object_type_t ot, int blocksize,
 257     int indirect_blockshift, dmu_object_type_t bonustype, int bonuslen,
 258     int dnodesize, dnode_t **allocated_dnode, const void *tag, dmu_tx_t *tx)
 259 {
 260         return (dmu_object_alloc_impl(os, ot, blocksize, indirect_blockshift,
 261             bonustype, bonuslen, dnodesize, allocated_dnode, tag, tx));
 262 }
 263
 264 int
 265 dmu_object_claim(objset_t *os, uint64_t object, dmu_object_type_t ot,
 266     int blocksize, dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
 267 {
 268         return (dmu_object_claim_dnsize(os, object, ot, blocksize, bonustype,
 269             bonuslen, 0, tx));
 270 }
 271
 272 int
 273 dmu_object_claim_dnsize(objset_t *os, uint64_t object, dmu_object_type_t ot,
 274     int blocksize, dmu_object_type_t bonustype, int bonuslen,
 275     int dnodesize, dmu_tx_t *tx)
 276 {
 277         dnode_t *dn;
 278         int dn_slots = dnodesize >> DNODE_SHIFT;
 279         int err;
 280
 281         if (dn_slots == 0)
 282                 dn_slots = DNODE_MIN_SLOTS;
 283         ASSERT3S(dn_slots, >=, DNODE_MIN_SLOTS);
 284         ASSERT3S(dn_slots, <=, DNODE_MAX_SLOTS);
 285
 286         if (object == DMU_META_DNODE_OBJECT && !dmu_tx_private_ok(tx))
 287                 return (SET_ERROR(EBADF));
 288
 289         err = dnode_hold_impl(os, object, DNODE_MUST_BE_FREE, dn_slots,
 290             FTAG, &dn);
 291         if (err)
 292                 return (err);
 293
 294         dnode_allocate(dn, ot, blocksize, 0, bonustype, bonuslen, dn_slots, tx);
 295         dmu_tx_add_new_object(tx, dn);
 296
 297         dnode_rele(dn, FTAG);
 298
 299         return (0);
 300 }
 301
 302 int
 303 dmu_object_reclaim(objset_t *os, uint64_t object, dmu_object_type_t ot,
 304     int blocksize, dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx)
 305 {
 306         return (dmu_object_reclaim_dnsize(os, object, ot, blocksize, bonustype,
 307             bonuslen, DNODE_MIN_SIZE, B_FALSE, tx));
 308 }
 309
 310 int
 311 dmu_object_reclaim_dnsize(objset_t *os, uint64_t object, dmu_object_type_t ot,
 312     int blocksize, dmu_object_type_t bonustype, int bonuslen, int dnodesize,
 313     boolean_t keep_spill, dmu_tx_t *tx)
 314 {
 315         dnode_t *dn;
 316         int dn_slots = dnodesize >> DNODE_SHIFT;
 317         int err;
 318
 319         if (dn_slots == 0)
 320                 dn_slots = DNODE_MIN_SLOTS;
 321
 322         if (object == DMU_META_DNODE_OBJECT)
 323                 return (SET_ERROR(EBADF));
 324
 325         err = dnode_hold_impl(os, object, DNODE_MUST_BE_ALLOCATED, 0,
 326             FTAG, &dn);
 327         if (err)
 328                 return (err);
 329
 330         dnode_reallocate(dn, ot, blocksize, bonustype, bonuslen, dn_slots,
 331             keep_spill, tx);
 332
 333         dnode_rele(dn, FTAG);
 334         return (err);
 335 }
 336
 337 int
 338 dmu_object_rm_spill(objset_t *os, uint64_t object, dmu_tx_t *tx)
 339 {
 340         dnode_t *dn;
 341         int err;
 342
 343         err = dnode_hold_impl(os, object, DNODE_MUST_BE_ALLOCATED, 0,
 344             FTAG, &dn);
 345         if (err)
 346                 return (err);
 347
 348         rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
 349         if (dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR) {
 350                 dbuf_rm_spill(dn, tx);
 351                 dnode_rm_spill(dn, tx);
 352         }
 353         rw_exit(&dn->dn_struct_rwlock);
 354
 355         dnode_rele(dn, FTAG);
 356         return (err);
 357 }
 358
 359 int
 360 dmu_object_free(objset_t *os, uint64_t object, dmu_tx_t *tx)
 361 {
 362         dnode_t *dn;
 363         int err;
 364
 365         ASSERT(object != DMU_META_DNODE_OBJECT || dmu_tx_private_ok(tx));
 366
 367         err = dnode_hold_impl(os, object, DNODE_MUST_BE_ALLOCATED, 0,
 368             FTAG, &dn);
 369         if (err)
 370                 return (err);
 371
 372         ASSERT(dn->dn_type != DMU_OT_NONE);
 373         /*
 374          * If we don't create this free range, we'll leak indirect blocks when
 375          * we get to freeing the dnode in syncing context.
 376          */
 377         dnode_free_range(dn, 0, DMU_OBJECT_END, tx);
 378         dnode_free(dn, tx);
 379         dnode_rele(dn, FTAG);
 380
 381         return (0);
 382 }
 383
 384 /*
 385  * Return (in *objectp) the next object which is allocated (or a hole)
 386  * after *object, taking into account only objects that may have been modified
 387  * after the specified txg.
 388  */
 389 int
 390 dmu_object_next(objset_t *os, uint64_t *objectp, boolean_t hole, uint64_t txg)
 391 {
 392         uint64_t offset;
 393         uint64_t start_obj;
 394         struct dsl_dataset *ds = os->os_dsl_dataset;
 395         int error;
 396
 397         if (*objectp == 0) {
 398                 start_obj = 1;
 399         } else if (ds && dsl_dataset_feature_is_active(ds,
 400             SPA_FEATURE_LARGE_DNODE)) {
 401                 uint64_t i = *objectp + 1;
 402                 uint64_t last_obj = *objectp | (DNODES_PER_BLOCK - 1);
 403                 dmu_object_info_t doi;
 404
 405                 /*
 406                  * Scan through the remaining meta dnode block.  The contents
 407                  * of each slot in the block are known so it can be quickly
 408                  * checked.  If the block is exhausted without a match then
 409                  * hand off to dnode_next_offset() for further scanning.
 410                  */
 411                 while (i <= last_obj) {
 412                         if (i == 0)
 413                                 return (SET_ERROR(ESRCH));
 414                         error = dmu_object_info(os, i, &doi);
 415                         if (error == ENOENT) {
 416                                 if (hole) {
 417                                         *objectp = i;
 418                                         return (0);
 419                                 } else {
 420                                         i++;
 421                                 }
 422                         } else if (error == EEXIST) {
 423                                 i++;
 424                         } else if (error == 0) {
 425                                 if (hole) {
 426                                         i += doi.doi_dnodesize >> DNODE_SHIFT;
 427                                 } else {
 428                                         *objectp = i;
 429                                         return (0);
 430                                 }
 431                         } else {
 432                                 return (error);
 433                         }
 434                 }
 435
 436                 start_obj = i;
 437         } else {
 438                 start_obj = *objectp + 1;
 439         }
 440
 441         offset = start_obj << DNODE_SHIFT;
 442
 443         error = dnode_next_offset(DMU_META_DNODE(os),
 444             (hole ? DNODE_FIND_HOLE : 0), &offset, 0, DNODES_PER_BLOCK, txg);
 445
 446         *objectp = offset >> DNODE_SHIFT;
 447
 448         return (error);
 449 }
 450
 451 /*
 452  * Turn this object from old_type into DMU_OTN_ZAP_METADATA, and bump the
 453  * refcount on SPA_FEATURE_EXTENSIBLE_DATASET.
 454  *
 455  * Only for use from syncing context, on MOS objects.
 456  */
 457 void
 458 dmu_object_zapify(objset_t *mos, uint64_t object, dmu_object_type_t old_type,
 459     dmu_tx_t *tx)
 460 {
 461         dnode_t *dn;
 462
 463         ASSERT(dmu_tx_is_syncing(tx));
 464
 465         VERIFY0(dnode_hold(mos, object, FTAG, &dn));
 466         if (dn->dn_type == DMU_OTN_ZAP_METADATA) {
 467                 dnode_rele(dn, FTAG);
 468                 return;
 469         }
 470         ASSERT3U(dn->dn_type, ==, old_type);
 471         ASSERT0(dn->dn_maxblkid);
 472
 473         /*
 474          * We must initialize the ZAP data before changing the type,
 475          * so that concurrent calls to *_is_zapified() can determine if
 476          * the object has been completely zapified by checking the type.
 477          */
 478         mzap_create_impl(dn, 0, 0, tx);
 479
 480         dn->dn_next_type[tx->tx_txg & TXG_MASK] = dn->dn_type =
 481             DMU_OTN_ZAP_METADATA;
 482         dnode_setdirty(dn, tx);
 483         dnode_rele(dn, FTAG);
 484
 485         spa_feature_incr(dmu_objset_spa(mos),
 486             SPA_FEATURE_EXTENSIBLE_DATASET, tx);
 487 }
 488
 489 void
 490 dmu_object_free_zapified(objset_t *mos, uint64_t object, dmu_tx_t *tx)
 491 {
 492         dnode_t *dn;
 493         dmu_object_type_t t;
 494
 495         ASSERT(dmu_tx_is_syncing(tx));
 496
 497         VERIFY0(dnode_hold(mos, object, FTAG, &dn));
 498         t = dn->dn_type;
 499         dnode_rele(dn, FTAG);
 500
 501         if (t == DMU_OTN_ZAP_METADATA) {
 502                 spa_feature_decr(dmu_objset_spa(mos),
 503                     SPA_FEATURE_EXTENSIBLE_DATASET, tx);
 504         }
 505         VERIFY0(dmu_object_free(mos, object, tx));
 506 }
 507
 508 EXPORT_SYMBOL(dmu_object_alloc);
 509 EXPORT_SYMBOL(dmu_object_alloc_ibs);
 510 EXPORT_SYMBOL(dmu_object_alloc_dnsize);
 511 EXPORT_SYMBOL(dmu_object_alloc_hold);
 512 EXPORT_SYMBOL(dmu_object_claim);
 513 EXPORT_SYMBOL(dmu_object_claim_dnsize);
 514 EXPORT_SYMBOL(dmu_object_reclaim);
 515 EXPORT_SYMBOL(dmu_object_reclaim_dnsize);
 516 EXPORT_SYMBOL(dmu_object_rm_spill);
 517 EXPORT_SYMBOL(dmu_object_free);
 518 EXPORT_SYMBOL(dmu_object_next);
 519 EXPORT_SYMBOL(dmu_object_zapify);
 520 EXPORT_SYMBOL(dmu_object_free_zapified);
 521
 522 /* BEGIN CSTYLED */
 523 ZFS_MODULE_PARAM(zfs, , dmu_object_alloc_chunk_shift, UINT, ZMOD_RW,
 524         "CPU-specific allocator grabs 2^N objects at once");
 525 /* END CSTYLED */