module/zfs/ddt.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 /*
  23  * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Copyright (c) 2012, 2016 by Delphix. All rights reserved.
  25  * Copyright (c) 2022 by Pawel Jakub Dawidek
  26  */
  27
  28 #include <sys/zfs_context.h>
  29 #include <sys/spa.h>
  30 #include <sys/spa_impl.h>
  31 #include <sys/zio.h>
  32 #include <sys/ddt.h>
  33 #include <sys/zap.h>
  34 #include <sys/dmu_tx.h>
  35 #include <sys/arc.h>
  36 #include <sys/dsl_pool.h>
  37 #include <sys/zio_checksum.h>
  38 #include <sys/dsl_scan.h>
  39 #include <sys/abd.h>
  40
  41 static kmem_cache_t *ddt_cache;
  42 static kmem_cache_t *ddt_entry_cache;
  43
  44 /*
  45  * Enable/disable prefetching of dedup-ed blocks which are going to be freed.
  46  */
  47 int zfs_dedup_prefetch = 0;
  48
  49 static const ddt_ops_t *const ddt_ops[DDT_TYPES] = {
  50         &ddt_zap_ops,
  51 };
  52
  53 static const char *const ddt_class_name[DDT_CLASSES] = {
  54         "ditto",
  55         "duplicate",
  56         "unique",
  57 };
  58
  59 static void
  60 ddt_object_create(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
  61     dmu_tx_t *tx)
  62 {
  63         spa_t *spa = ddt->ddt_spa;
  64         objset_t *os = ddt->ddt_os;
  65         uint64_t *objectp = &ddt->ddt_object[type][class];
  66         boolean_t prehash = zio_checksum_table[ddt->ddt_checksum].ci_flags &
  67             ZCHECKSUM_FLAG_DEDUP;
  68         char name[DDT_NAMELEN];
  69
  70         ddt_object_name(ddt, type, class, name);
  71
  72         ASSERT3U(*objectp, ==, 0);
  73         VERIFY0(ddt_ops[type]->ddt_op_create(os, objectp, tx, prehash));
  74         ASSERT3U(*objectp, !=, 0);
  75
  76         VERIFY0(zap_add(os, DMU_POOL_DIRECTORY_OBJECT, name,
  77             sizeof (uint64_t), 1, objectp, tx));
  78
  79         VERIFY0(zap_add(os, spa->spa_ddt_stat_object, name,
  80             sizeof (uint64_t), sizeof (ddt_histogram_t) / sizeof (uint64_t),
  81             &ddt->ddt_histogram[type][class], tx));
  82 }
  83
  84 static void
  85 ddt_object_destroy(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
  86     dmu_tx_t *tx)
  87 {
  88         spa_t *spa = ddt->ddt_spa;
  89         objset_t *os = ddt->ddt_os;
  90         uint64_t *objectp = &ddt->ddt_object[type][class];
  91         uint64_t count;
  92         char name[DDT_NAMELEN];
  93
  94         ddt_object_name(ddt, type, class, name);
  95
  96         ASSERT3U(*objectp, !=, 0);
  97         ASSERT(ddt_histogram_empty(&ddt->ddt_histogram[type][class]));
  98         VERIFY0(ddt_object_count(ddt, type, class, &count));
  99         VERIFY0(count);
 100         VERIFY0(zap_remove(os, DMU_POOL_DIRECTORY_OBJECT, name, tx));
 101         VERIFY0(zap_remove(os, spa->spa_ddt_stat_object, name, tx));
 102         VERIFY0(ddt_ops[type]->ddt_op_destroy(os, *objectp, tx));
 103         memset(&ddt->ddt_object_stats[type][class], 0, sizeof (ddt_object_t));
 104
 105         *objectp = 0;
 106 }
 107
 108 static int
 109 ddt_object_load(ddt_t *ddt, enum ddt_type type, enum ddt_class class)
 110 {
 111         ddt_object_t *ddo = &ddt->ddt_object_stats[type][class];
 112         dmu_object_info_t doi;
 113         uint64_t count;
 114         char name[DDT_NAMELEN];
 115         int error;
 116
 117         ddt_object_name(ddt, type, class, name);
 118
 119         error = zap_lookup(ddt->ddt_os, DMU_POOL_DIRECTORY_OBJECT, name,
 120             sizeof (uint64_t), 1, &ddt->ddt_object[type][class]);
 121         if (error != 0)
 122                 return (error);
 123
 124         error = zap_lookup(ddt->ddt_os, ddt->ddt_spa->spa_ddt_stat_object, name,
 125             sizeof (uint64_t), sizeof (ddt_histogram_t) / sizeof (uint64_t),
 126             &ddt->ddt_histogram[type][class]);
 127         if (error != 0)
 128                 return (error);
 129
 130         /*
 131          * Seed the cached statistics.
 132          */
 133         error = ddt_object_info(ddt, type, class, &doi);
 134         if (error)
 135                 return (error);
 136
 137         error = ddt_object_count(ddt, type, class, &count);
 138         if (error)
 139                 return (error);
 140
 141         ddo->ddo_count = count;
 142         ddo->ddo_dspace = doi.doi_physical_blocks_512 << 9;
 143         ddo->ddo_mspace = doi.doi_fill_count * doi.doi_data_block_size;
 144
 145         return (0);
 146 }
 147
 148 static void
 149 ddt_object_sync(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 150     dmu_tx_t *tx)
 151 {
 152         ddt_object_t *ddo = &ddt->ddt_object_stats[type][class];
 153         dmu_object_info_t doi;
 154         uint64_t count;
 155         char name[DDT_NAMELEN];
 156
 157         ddt_object_name(ddt, type, class, name);
 158
 159         VERIFY0(zap_update(ddt->ddt_os, ddt->ddt_spa->spa_ddt_stat_object, name,
 160             sizeof (uint64_t), sizeof (ddt_histogram_t) / sizeof (uint64_t),
 161             &ddt->ddt_histogram[type][class], tx));
 162
 163         /*
 164          * Cache DDT statistics; this is the only time they'll change.
 165          */
 166         VERIFY0(ddt_object_info(ddt, type, class, &doi));
 167         VERIFY0(ddt_object_count(ddt, type, class, &count));
 168
 169         ddo->ddo_count = count;
 170         ddo->ddo_dspace = doi.doi_physical_blocks_512 << 9;
 171         ddo->ddo_mspace = doi.doi_fill_count * doi.doi_data_block_size;
 172 }
 173
 174 static int
 175 ddt_object_lookup(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 176     ddt_entry_t *dde)
 177 {
 178         if (!ddt_object_exists(ddt, type, class))
 179                 return (SET_ERROR(ENOENT));
 180
 181         return (ddt_ops[type]->ddt_op_lookup(ddt->ddt_os,
 182             ddt->ddt_object[type][class], dde));
 183 }
 184
 185 static void
 186 ddt_object_prefetch(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 187     ddt_entry_t *dde)
 188 {
 189         if (!ddt_object_exists(ddt, type, class))
 190                 return;
 191
 192         ddt_ops[type]->ddt_op_prefetch(ddt->ddt_os,
 193             ddt->ddt_object[type][class], dde);
 194 }
 195
 196 int
 197 ddt_object_update(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 198     ddt_entry_t *dde, dmu_tx_t *tx)
 199 {
 200         ASSERT(ddt_object_exists(ddt, type, class));
 201
 202         return (ddt_ops[type]->ddt_op_update(ddt->ddt_os,
 203             ddt->ddt_object[type][class], dde, tx));
 204 }
 205
 206 static int
 207 ddt_object_remove(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 208     ddt_entry_t *dde, dmu_tx_t *tx)
 209 {
 210         ASSERT(ddt_object_exists(ddt, type, class));
 211
 212         return (ddt_ops[type]->ddt_op_remove(ddt->ddt_os,
 213             ddt->ddt_object[type][class], dde, tx));
 214 }
 215
 216 int
 217 ddt_object_walk(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 218     uint64_t *walk, ddt_entry_t *dde)
 219 {
 220         ASSERT(ddt_object_exists(ddt, type, class));
 221
 222         return (ddt_ops[type]->ddt_op_walk(ddt->ddt_os,
 223             ddt->ddt_object[type][class], dde, walk));
 224 }
 225
 226 int
 227 ddt_object_count(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 228     uint64_t *count)
 229 {
 230         ASSERT(ddt_object_exists(ddt, type, class));
 231
 232         return (ddt_ops[type]->ddt_op_count(ddt->ddt_os,
 233             ddt->ddt_object[type][class], count));
 234 }
 235
 236 int
 237 ddt_object_info(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 238     dmu_object_info_t *doi)
 239 {
 240         if (!ddt_object_exists(ddt, type, class))
 241                 return (SET_ERROR(ENOENT));
 242
 243         return (dmu_object_info(ddt->ddt_os, ddt->ddt_object[type][class],
 244             doi));
 245 }
 246
 247 boolean_t
 248 ddt_object_exists(ddt_t *ddt, enum ddt_type type, enum ddt_class class)
 249 {
 250         return (!!ddt->ddt_object[type][class]);
 251 }
 252
 253 void
 254 ddt_object_name(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 255     char *name)
 256 {
 257         (void) snprintf(name, DDT_NAMELEN, DMU_POOL_DDT,
 258             zio_checksum_table[ddt->ddt_checksum].ci_name,
 259             ddt_ops[type]->ddt_op_name, ddt_class_name[class]);
 260 }
 261
 262 void
 263 ddt_bp_fill(const ddt_phys_t *ddp, blkptr_t *bp, uint64_t txg)
 264 {
 265         ASSERT3U(txg, !=, 0);
 266
 267         for (int d = 0; d < SPA_DVAS_PER_BP; d++)
 268                 bp->blk_dva[d] = ddp->ddp_dva[d];
 269         BP_SET_BIRTH(bp, txg, ddp->ddp_phys_birth);
 270 }
 271
 272 /*
 273  * The bp created via this function may be used for repairs and scrub, but it
 274  * will be missing the salt / IV required to do a full decrypting read.
 275  */
 276 void
 277 ddt_bp_create(enum zio_checksum checksum,
 278     const ddt_key_t *ddk, const ddt_phys_t *ddp, blkptr_t *bp)
 279 {
 280         BP_ZERO(bp);
 281
 282         if (ddp != NULL)
 283                 ddt_bp_fill(ddp, bp, ddp->ddp_phys_birth);
 284
 285         bp->blk_cksum = ddk->ddk_cksum;
 286
 287         BP_SET_LSIZE(bp, DDK_GET_LSIZE(ddk));
 288         BP_SET_PSIZE(bp, DDK_GET_PSIZE(ddk));
 289         BP_SET_COMPRESS(bp, DDK_GET_COMPRESS(ddk));
 290         BP_SET_CRYPT(bp, DDK_GET_CRYPT(ddk));
 291         BP_SET_FILL(bp, 1);
 292         BP_SET_CHECKSUM(bp, checksum);
 293         BP_SET_TYPE(bp, DMU_OT_DEDUP);
 294         BP_SET_LEVEL(bp, 0);
 295         BP_SET_DEDUP(bp, 1);
 296         BP_SET_BYTEORDER(bp, ZFS_HOST_BYTEORDER);
 297 }
 298
 299 void
 300 ddt_key_fill(ddt_key_t *ddk, const blkptr_t *bp)
 301 {
 302         ddk->ddk_cksum = bp->blk_cksum;
 303         ddk->ddk_prop = 0;
 304
 305         ASSERT(BP_IS_ENCRYPTED(bp) || !BP_USES_CRYPT(bp));
 306
 307         DDK_SET_LSIZE(ddk, BP_GET_LSIZE(bp));
 308         DDK_SET_PSIZE(ddk, BP_GET_PSIZE(bp));
 309         DDK_SET_COMPRESS(ddk, BP_GET_COMPRESS(bp));
 310         DDK_SET_CRYPT(ddk, BP_USES_CRYPT(bp));
 311 }
 312
 313 void
 314 ddt_phys_fill(ddt_phys_t *ddp, const blkptr_t *bp)
 315 {
 316         ASSERT0(ddp->ddp_phys_birth);
 317
 318         for (int d = 0; d < SPA_DVAS_PER_BP; d++)
 319                 ddp->ddp_dva[d] = bp->blk_dva[d];
 320         ddp->ddp_phys_birth = BP_PHYSICAL_BIRTH(bp);
 321 }
 322
 323 void
 324 ddt_phys_clear(ddt_phys_t *ddp)
 325 {
 326         memset(ddp, 0, sizeof (*ddp));
 327 }
 328
 329 void
 330 ddt_phys_addref(ddt_phys_t *ddp)
 331 {
 332         ddp->ddp_refcnt++;
 333 }
 334
 335 void
 336 ddt_phys_decref(ddt_phys_t *ddp)
 337 {
 338         if (ddp) {
 339                 ASSERT3U(ddp->ddp_refcnt, >, 0);
 340                 ddp->ddp_refcnt--;
 341         }
 342 }
 343
 344 void
 345 ddt_phys_free(ddt_t *ddt, ddt_key_t *ddk, ddt_phys_t *ddp, uint64_t txg)
 346 {
 347         blkptr_t blk;
 348
 349         ddt_bp_create(ddt->ddt_checksum, ddk, ddp, &blk);
 350
 351         /*
 352          * We clear the dedup bit so that zio_free() will actually free the
 353          * space, rather than just decrementing the refcount in the DDT.
 354          */
 355         BP_SET_DEDUP(&blk, 0);
 356
 357         ddt_phys_clear(ddp);
 358         zio_free(ddt->ddt_spa, txg, &blk);
 359 }
 360
 361 ddt_phys_t *
 362 ddt_phys_select(const ddt_entry_t *dde, const blkptr_t *bp)
 363 {
 364         ddt_phys_t *ddp = (ddt_phys_t *)dde->dde_phys;
 365
 366         for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
 367                 if (DVA_EQUAL(BP_IDENTITY(bp), &ddp->ddp_dva[0]) &&
 368                     BP_PHYSICAL_BIRTH(bp) == ddp->ddp_phys_birth)
 369                         return (ddp);
 370         }
 371         return (NULL);
 372 }
 373
 374 uint64_t
 375 ddt_phys_total_refcnt(const ddt_entry_t *dde)
 376 {
 377         uint64_t refcnt = 0;
 378
 379         for (int p = DDT_PHYS_SINGLE; p <= DDT_PHYS_TRIPLE; p++)
 380                 refcnt += dde->dde_phys[p].ddp_refcnt;
 381
 382         return (refcnt);
 383 }
 384
 385 ddt_t *
 386 ddt_select(spa_t *spa, const blkptr_t *bp)
 387 {
 388         return (spa->spa_ddt[BP_GET_CHECKSUM(bp)]);
 389 }
 390
 391 void
 392 ddt_enter(ddt_t *ddt)
 393 {
 394         mutex_enter(&ddt->ddt_lock);
 395 }
 396
 397 void
 398 ddt_exit(ddt_t *ddt)
 399 {
 400         mutex_exit(&ddt->ddt_lock);
 401 }
 402
 403 void
 404 ddt_init(void)
 405 {
 406         ddt_cache = kmem_cache_create("ddt_cache",
 407             sizeof (ddt_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
 408         ddt_entry_cache = kmem_cache_create("ddt_entry_cache",
 409             sizeof (ddt_entry_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
 410 }
 411
 412 void
 413 ddt_fini(void)
 414 {
 415         kmem_cache_destroy(ddt_entry_cache);
 416         kmem_cache_destroy(ddt_cache);
 417 }
 418
 419 static ddt_entry_t *
 420 ddt_alloc(const ddt_key_t *ddk)
 421 {
 422         ddt_entry_t *dde;
 423
 424         dde = kmem_cache_alloc(ddt_entry_cache, KM_SLEEP);
 425         memset(dde, 0, sizeof (ddt_entry_t));
 426         cv_init(&dde->dde_cv, NULL, CV_DEFAULT, NULL);
 427
 428         dde->dde_key = *ddk;
 429
 430         return (dde);
 431 }
 432
 433 static void
 434 ddt_free(ddt_entry_t *dde)
 435 {
 436         ASSERT(!dde->dde_loading);
 437
 438         for (int p = 0; p < DDT_PHYS_TYPES; p++)
 439                 ASSERT3P(dde->dde_lead_zio[p], ==, NULL);
 440
 441         if (dde->dde_repair_abd != NULL)
 442                 abd_free(dde->dde_repair_abd);
 443
 444         cv_destroy(&dde->dde_cv);
 445         kmem_cache_free(ddt_entry_cache, dde);
 446 }
 447
 448 void
 449 ddt_remove(ddt_t *ddt, ddt_entry_t *dde)
 450 {
 451         ASSERT(MUTEX_HELD(&ddt->ddt_lock));
 452
 453         avl_remove(&ddt->ddt_tree, dde);
 454         ddt_free(dde);
 455 }
 456
 457 ddt_entry_t *
 458 ddt_lookup(ddt_t *ddt, const blkptr_t *bp, boolean_t add)
 459 {
 460         ddt_key_t search;
 461         ddt_entry_t *dde;
 462         enum ddt_type type;
 463         enum ddt_class class;
 464         avl_index_t where;
 465         int error;
 466
 467         ASSERT(MUTEX_HELD(&ddt->ddt_lock));
 468
 469         ddt_key_fill(&search, bp);
 470
 471         dde = avl_find(&ddt->ddt_tree, &search, &where);
 472         if (dde == NULL) {
 473                 if (!add)
 474                         return (NULL);
 475                 dde = ddt_alloc(&search);
 476                 avl_insert(&ddt->ddt_tree, dde, where);
 477         }
 478
 479         while (dde->dde_loading)
 480                 cv_wait(&dde->dde_cv, &ddt->ddt_lock);
 481
 482         if (dde->dde_loaded)
 483                 return (dde);
 484
 485         dde->dde_loading = B_TRUE;
 486
 487         ddt_exit(ddt);
 488
 489         error = ENOENT;
 490
 491         for (type = 0; type < DDT_TYPES; type++) {
 492                 for (class = 0; class < DDT_CLASSES; class++) {
 493                         error = ddt_object_lookup(ddt, type, class, dde);
 494                         if (error != ENOENT) {
 495                                 ASSERT0(error);
 496                                 break;
 497                         }
 498                 }
 499                 if (error != ENOENT)
 500                         break;
 501         }
 502
 503         ddt_enter(ddt);
 504
 505         ASSERT(!dde->dde_loaded);
 506         ASSERT(dde->dde_loading);
 507
 508         dde->dde_type = type;   /* will be DDT_TYPES if no entry found */
 509         dde->dde_class = class; /* will be DDT_CLASSES if no entry found */
 510         dde->dde_loaded = B_TRUE;
 511         dde->dde_loading = B_FALSE;
 512
 513         if (error == 0)
 514                 ddt_stat_update(ddt, dde, -1ULL);
 515
 516         cv_broadcast(&dde->dde_cv);
 517
 518         return (dde);
 519 }
 520
 521 void
 522 ddt_prefetch(spa_t *spa, const blkptr_t *bp)
 523 {
 524         ddt_t *ddt;
 525         ddt_entry_t dde;
 526
 527         if (!zfs_dedup_prefetch || bp == NULL || !BP_GET_DEDUP(bp))
 528                 return;
 529
 530         /*
 531          * We only remove the DDT once all tables are empty and only
 532          * prefetch dedup blocks when there are entries in the DDT.
 533          * Thus no locking is required as the DDT can't disappear on us.
 534          */
 535         ddt = ddt_select(spa, bp);
 536         ddt_key_fill(&dde.dde_key, bp);
 537
 538         for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
 539                 for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
 540                         ddt_object_prefetch(ddt, type, class, &dde);
 541                 }
 542         }
 543 }
 544
 545 /*
 546  * Key comparison. Any struct wanting to make use of this function must have
 547  * the key as the first element.
 548  */
 549 #define DDT_KEY_CMP_LEN (sizeof (ddt_key_t) / sizeof (uint16_t))
 550
 551 typedef struct ddt_key_cmp {
 552         uint16_t        u16[DDT_KEY_CMP_LEN];
 553 } ddt_key_cmp_t;
 554
 555 int
 556 ddt_key_compare(const void *x1, const void *x2)
 557 {
 558         const ddt_key_cmp_t *k1 = (const ddt_key_cmp_t *)x1;
 559         const ddt_key_cmp_t *k2 = (const ddt_key_cmp_t *)x2;
 560         int32_t cmp = 0;
 561
 562         for (int i = 0; i < DDT_KEY_CMP_LEN; i++) {
 563                 cmp = (int32_t)k1->u16[i] - (int32_t)k2->u16[i];
 564                 if (likely(cmp))
 565                         break;
 566         }
 567
 568         return (TREE_ISIGN(cmp));
 569 }
 570
 571 static ddt_t *
 572 ddt_table_alloc(spa_t *spa, enum zio_checksum c)
 573 {
 574         ddt_t *ddt;
 575
 576         ddt = kmem_cache_alloc(ddt_cache, KM_SLEEP);
 577         memset(ddt, 0, sizeof (ddt_t));
 578
 579         mutex_init(&ddt->ddt_lock, NULL, MUTEX_DEFAULT, NULL);
 580         avl_create(&ddt->ddt_tree, ddt_key_compare,
 581             sizeof (ddt_entry_t), offsetof(ddt_entry_t, dde_node));
 582         avl_create(&ddt->ddt_repair_tree, ddt_key_compare,
 583             sizeof (ddt_entry_t), offsetof(ddt_entry_t, dde_node));
 584         ddt->ddt_checksum = c;
 585         ddt->ddt_spa = spa;
 586         ddt->ddt_os = spa->spa_meta_objset;
 587
 588         return (ddt);
 589 }
 590
 591 static void
 592 ddt_table_free(ddt_t *ddt)
 593 {
 594         ASSERT0(avl_numnodes(&ddt->ddt_tree));
 595         ASSERT0(avl_numnodes(&ddt->ddt_repair_tree));
 596         avl_destroy(&ddt->ddt_tree);
 597         avl_destroy(&ddt->ddt_repair_tree);
 598         mutex_destroy(&ddt->ddt_lock);
 599         kmem_cache_free(ddt_cache, ddt);
 600 }
 601
 602 void
 603 ddt_create(spa_t *spa)
 604 {
 605         spa->spa_dedup_checksum = ZIO_DEDUPCHECKSUM;
 606
 607         for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++)
 608                 spa->spa_ddt[c] = ddt_table_alloc(spa, c);
 609 }
 610
 611 int
 612 ddt_load(spa_t *spa)
 613 {
 614         int error;
 615
 616         ddt_create(spa);
 617
 618         error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 619             DMU_POOL_DDT_STATS, sizeof (uint64_t), 1,
 620             &spa->spa_ddt_stat_object);
 621
 622         if (error)
 623                 return (error == ENOENT ? 0 : error);
 624
 625         for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
 626                 ddt_t *ddt = spa->spa_ddt[c];
 627                 for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
 628                         for (enum ddt_class class = 0; class < DDT_CLASSES;
 629                             class++) {
 630                                 error = ddt_object_load(ddt, type, class);
 631                                 if (error != 0 && error != ENOENT)
 632                                         return (error);
 633                         }
 634                 }
 635
 636                 /*
 637                  * Seed the cached histograms.
 638                  */
 639                 memcpy(&ddt->ddt_histogram_cache, ddt->ddt_histogram,
 640                     sizeof (ddt->ddt_histogram));
 641                 spa->spa_dedup_dspace = ~0ULL;
 642         }
 643
 644         return (0);
 645 }
 646
 647 void
 648 ddt_unload(spa_t *spa)
 649 {
 650         for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
 651                 if (spa->spa_ddt[c]) {
 652                         ddt_table_free(spa->spa_ddt[c]);
 653                         spa->spa_ddt[c] = NULL;
 654                 }
 655         }
 656 }
 657
 658 boolean_t
 659 ddt_class_contains(spa_t *spa, enum ddt_class max_class, const blkptr_t *bp)
 660 {
 661         ddt_t *ddt;
 662         ddt_entry_t *dde;
 663
 664         if (!BP_GET_DEDUP(bp))
 665                 return (B_FALSE);
 666
 667         if (max_class == DDT_CLASS_UNIQUE)
 668                 return (B_TRUE);
 669
 670         ddt = spa->spa_ddt[BP_GET_CHECKSUM(bp)];
 671         dde = kmem_cache_alloc(ddt_entry_cache, KM_SLEEP);
 672
 673         ddt_key_fill(&(dde->dde_key), bp);
 674
 675         for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
 676                 for (enum ddt_class class = 0; class <= max_class; class++) {
 677                         if (ddt_object_lookup(ddt, type, class, dde) == 0) {
 678                                 kmem_cache_free(ddt_entry_cache, dde);
 679                                 return (B_TRUE);
 680                         }
 681                 }
 682         }
 683
 684         kmem_cache_free(ddt_entry_cache, dde);
 685         return (B_FALSE);
 686 }
 687
 688 ddt_entry_t *
 689 ddt_repair_start(ddt_t *ddt, const blkptr_t *bp)
 690 {
 691         ddt_key_t ddk;
 692         ddt_entry_t *dde;
 693
 694         ddt_key_fill(&ddk, bp);
 695
 696         dde = ddt_alloc(&ddk);
 697
 698         for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
 699                 for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
 700                         /*
 701                          * We can only do repair if there are multiple copies
 702                          * of the block.  For anything in the UNIQUE class,
 703                          * there's definitely only one copy, so don't even try.
 704                          */
 705                         if (class != DDT_CLASS_UNIQUE &&
 706                             ddt_object_lookup(ddt, type, class, dde) == 0)
 707                                 return (dde);
 708                 }
 709         }
 710
 711         memset(dde->dde_phys, 0, sizeof (dde->dde_phys));
 712
 713         return (dde);
 714 }
 715
 716 void
 717 ddt_repair_done(ddt_t *ddt, ddt_entry_t *dde)
 718 {
 719         avl_index_t where;
 720
 721         ddt_enter(ddt);
 722
 723         if (dde->dde_repair_abd != NULL && spa_writeable(ddt->ddt_spa) &&
 724             avl_find(&ddt->ddt_repair_tree, dde, &where) == NULL)
 725                 avl_insert(&ddt->ddt_repair_tree, dde, where);
 726         else
 727                 ddt_free(dde);
 728
 729         ddt_exit(ddt);
 730 }
 731
 732 static void
 733 ddt_repair_entry_done(zio_t *zio)
 734 {
 735         ddt_entry_t *rdde = zio->io_private;
 736
 737         ddt_free(rdde);
 738 }
 739
 740 static void
 741 ddt_repair_entry(ddt_t *ddt, ddt_entry_t *dde, ddt_entry_t *rdde, zio_t *rio)
 742 {
 743         ddt_phys_t *ddp = dde->dde_phys;
 744         ddt_phys_t *rddp = rdde->dde_phys;
 745         ddt_key_t *ddk = &dde->dde_key;
 746         ddt_key_t *rddk = &rdde->dde_key;
 747         zio_t *zio;
 748         blkptr_t blk;
 749
 750         zio = zio_null(rio, rio->io_spa, NULL,
 751             ddt_repair_entry_done, rdde, rio->io_flags);
 752
 753         for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++, rddp++) {
 754                 if (ddp->ddp_phys_birth == 0 ||
 755                     ddp->ddp_phys_birth != rddp->ddp_phys_birth ||
 756                     memcmp(ddp->ddp_dva, rddp->ddp_dva, sizeof (ddp->ddp_dva)))
 757                         continue;
 758                 ddt_bp_create(ddt->ddt_checksum, ddk, ddp, &blk);
 759                 zio_nowait(zio_rewrite(zio, zio->io_spa, 0, &blk,
 760                     rdde->dde_repair_abd, DDK_GET_PSIZE(rddk), NULL, NULL,
 761                     ZIO_PRIORITY_SYNC_WRITE, ZIO_DDT_CHILD_FLAGS(zio), NULL));
 762         }
 763
 764         zio_nowait(zio);
 765 }
 766
 767 static void
 768 ddt_repair_table(ddt_t *ddt, zio_t *rio)
 769 {
 770         spa_t *spa = ddt->ddt_spa;
 771         ddt_entry_t *dde, *rdde_next, *rdde;
 772         avl_tree_t *t = &ddt->ddt_repair_tree;
 773         blkptr_t blk;
 774
 775         if (spa_sync_pass(spa) > 1)
 776                 return;
 777
 778         ddt_enter(ddt);
 779         for (rdde = avl_first(t); rdde != NULL; rdde = rdde_next) {
 780                 rdde_next = AVL_NEXT(t, rdde);
 781                 avl_remove(&ddt->ddt_repair_tree, rdde);
 782                 ddt_exit(ddt);
 783                 ddt_bp_create(ddt->ddt_checksum, &rdde->dde_key, NULL, &blk);
 784                 dde = ddt_repair_start(ddt, &blk);
 785                 ddt_repair_entry(ddt, dde, rdde, rio);
 786                 ddt_repair_done(ddt, dde);
 787                 ddt_enter(ddt);
 788         }
 789         ddt_exit(ddt);
 790 }
 791
 792 static void
 793 ddt_sync_entry(ddt_t *ddt, ddt_entry_t *dde, dmu_tx_t *tx, uint64_t txg)
 794 {
 795         dsl_pool_t *dp = ddt->ddt_spa->spa_dsl_pool;
 796         ddt_phys_t *ddp = dde->dde_phys;
 797         ddt_key_t *ddk = &dde->dde_key;
 798         enum ddt_type otype = dde->dde_type;
 799         enum ddt_type ntype = DDT_TYPE_CURRENT;
 800         enum ddt_class oclass = dde->dde_class;
 801         enum ddt_class nclass;
 802         uint64_t total_refcnt = 0;
 803
 804         ASSERT(dde->dde_loaded);
 805         ASSERT(!dde->dde_loading);
 806
 807         for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
 808                 ASSERT3P(dde->dde_lead_zio[p], ==, NULL);
 809                 if (ddp->ddp_phys_birth == 0) {
 810                         ASSERT0(ddp->ddp_refcnt);
 811                         continue;
 812                 }
 813                 if (p == DDT_PHYS_DITTO) {
 814                         /*
 815                          * Note, we no longer create DDT-DITTO blocks, but we
 816                          * don't want to leak any written by older software.
 817                          */
 818                         ddt_phys_free(ddt, ddk, ddp, txg);
 819                         continue;
 820                 }
 821                 if (ddp->ddp_refcnt == 0)
 822                         ddt_phys_free(ddt, ddk, ddp, txg);
 823                 total_refcnt += ddp->ddp_refcnt;
 824         }
 825
 826         /* We do not create new DDT-DITTO blocks. */
 827         ASSERT0(dde->dde_phys[DDT_PHYS_DITTO].ddp_phys_birth);
 828         if (total_refcnt > 1)
 829                 nclass = DDT_CLASS_DUPLICATE;
 830         else
 831                 nclass = DDT_CLASS_UNIQUE;
 832
 833         if (otype != DDT_TYPES &&
 834             (otype != ntype || oclass != nclass || total_refcnt == 0)) {
 835                 VERIFY0(ddt_object_remove(ddt, otype, oclass, dde, tx));
 836                 ASSERT3U(
 837                     ddt_object_lookup(ddt, otype, oclass, dde), ==, ENOENT);
 838         }
 839
 840         if (total_refcnt != 0) {
 841                 dde->dde_type = ntype;
 842                 dde->dde_class = nclass;
 843                 ddt_stat_update(ddt, dde, 0);
 844                 if (!ddt_object_exists(ddt, ntype, nclass))
 845                         ddt_object_create(ddt, ntype, nclass, tx);
 846                 VERIFY0(ddt_object_update(ddt, ntype, nclass, dde, tx));
 847
 848                 /*
 849                  * If the class changes, the order that we scan this bp
 850                  * changes.  If it decreases, we could miss it, so
 851                  * scan it right now.  (This covers both class changing
 852                  * while we are doing ddt_walk(), and when we are
 853                  * traversing.)
 854                  */
 855                 if (nclass < oclass) {
 856                         dsl_scan_ddt_entry(dp->dp_scan,
 857                             ddt->ddt_checksum, dde, tx);
 858                 }
 859         }
 860 }
 861
 862 static void
 863 ddt_sync_table(ddt_t *ddt, dmu_tx_t *tx, uint64_t txg)
 864 {
 865         spa_t *spa = ddt->ddt_spa;
 866         ddt_entry_t *dde;
 867         void *cookie = NULL;
 868
 869         if (avl_numnodes(&ddt->ddt_tree) == 0)
 870                 return;
 871
 872         ASSERT3U(spa->spa_uberblock.ub_version, >=, SPA_VERSION_DEDUP);
 873
 874         if (spa->spa_ddt_stat_object == 0) {
 875                 spa->spa_ddt_stat_object = zap_create_link(ddt->ddt_os,
 876                     DMU_OT_DDT_STATS, DMU_POOL_DIRECTORY_OBJECT,
 877                     DMU_POOL_DDT_STATS, tx);
 878         }
 879
 880         while ((dde = avl_destroy_nodes(&ddt->ddt_tree, &cookie)) != NULL) {
 881                 ddt_sync_entry(ddt, dde, tx, txg);
 882                 ddt_free(dde);
 883         }
 884
 885         for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
 886                 uint64_t add, count = 0;
 887                 for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
 888                         if (ddt_object_exists(ddt, type, class)) {
 889                                 ddt_object_sync(ddt, type, class, tx);
 890                                 VERIFY0(ddt_object_count(ddt, type, class,
 891                                     &add));
 892                                 count += add;
 893                         }
 894                 }
 895                 for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
 896                         if (count == 0 && ddt_object_exists(ddt, type, class))
 897                                 ddt_object_destroy(ddt, type, class, tx);
 898                 }
 899         }
 900
 901         memcpy(&ddt->ddt_histogram_cache, ddt->ddt_histogram,
 902             sizeof (ddt->ddt_histogram));
 903         spa->spa_dedup_dspace = ~0ULL;
 904 }
 905
 906 void
 907 ddt_sync(spa_t *spa, uint64_t txg)
 908 {
 909         dsl_scan_t *scn = spa->spa_dsl_pool->dp_scan;
 910         dmu_tx_t *tx;
 911         zio_t *rio;
 912
 913         ASSERT3U(spa_syncing_txg(spa), ==, txg);
 914
 915         tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
 916
 917         rio = zio_root(spa, NULL, NULL,
 918             ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SELF_HEAL);
 919
 920         /*
 921          * This function may cause an immediate scan of ddt blocks (see
 922          * the comment above dsl_scan_ddt() for details). We set the
 923          * scan's root zio here so that we can wait for any scan IOs in
 924          * addition to the regular ddt IOs.
 925          */
 926         ASSERT3P(scn->scn_zio_root, ==, NULL);
 927         scn->scn_zio_root = rio;
 928
 929         for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
 930                 ddt_t *ddt = spa->spa_ddt[c];
 931                 if (ddt == NULL)
 932                         continue;
 933                 ddt_sync_table(ddt, tx, txg);
 934                 ddt_repair_table(ddt, rio);
 935         }
 936
 937         (void) zio_wait(rio);
 938         scn->scn_zio_root = NULL;
 939
 940         dmu_tx_commit(tx);
 941 }
 942
 943 int
 944 ddt_walk(spa_t *spa, ddt_bookmark_t *ddb, ddt_entry_t *dde)
 945 {
 946         do {
 947                 do {
 948                         do {
 949                                 ddt_t *ddt = spa->spa_ddt[ddb->ddb_checksum];
 950                                 int error = ENOENT;
 951                                 if (ddt_object_exists(ddt, ddb->ddb_type,
 952                                     ddb->ddb_class)) {
 953                                         error = ddt_object_walk(ddt,
 954                                             ddb->ddb_type, ddb->ddb_class,
 955                                             &ddb->ddb_cursor, dde);
 956                                 }
 957                                 dde->dde_type = ddb->ddb_type;
 958                                 dde->dde_class = ddb->ddb_class;
 959                                 if (error == 0)
 960                                         return (0);
 961                                 if (error != ENOENT)
 962                                         return (error);
 963                                 ddb->ddb_cursor = 0;
 964                         } while (++ddb->ddb_checksum < ZIO_CHECKSUM_FUNCTIONS);
 965                         ddb->ddb_checksum = 0;
 966                 } while (++ddb->ddb_type < DDT_TYPES);
 967                 ddb->ddb_type = 0;
 968         } while (++ddb->ddb_class < DDT_CLASSES);
 969
 970         return (SET_ERROR(ENOENT));
 971 }
 972
 973 /*
 974  * This function is used by Block Cloning (brt.c) to increase reference
 975  * counter for the DDT entry if the block is already in DDT.
 976  *
 977  * Return false if the block, despite having the D bit set, is not present
 978  * in the DDT. Currently this is not possible but might be in the future.
 979  * See the comment below.
 980  */
 981 boolean_t
 982 ddt_addref(spa_t *spa, const blkptr_t *bp)
 983 {
 984         ddt_t *ddt;
 985         ddt_entry_t *dde;
 986         boolean_t result;
 987
 988         spa_config_enter(spa, SCL_ZIO, FTAG, RW_READER);
 989         ddt = ddt_select(spa, bp);
 990         ddt_enter(ddt);
 991
 992         dde = ddt_lookup(ddt, bp, B_TRUE);
 993         ASSERT3P(dde, !=, NULL);
 994
 995         if (dde->dde_type < DDT_TYPES) {
 996                 ddt_phys_t *ddp;
 997
 998                 ASSERT3S(dde->dde_class, <, DDT_CLASSES);
 999
1000                 ddp = &dde->dde_phys[BP_GET_NDVAS(bp)];
1001
1002                 /*
1003                  * This entry already existed (dde_type is real), so it must
1004                  * have refcnt >0 at the start of this txg. We are called from
1005                  * brt_pending_apply(), before frees are issued, so the refcnt
1006                  * can't be lowered yet. Therefore, it must be >0. We assert
1007                  * this because if the order of BRT and DDT interactions were
1008                  * ever to change and the refcnt was ever zero here, then
1009                  * likely further action is required to fill out the DDT entry,
1010                  * and this is a place that is likely to be missed in testing.
1011                  */
1012                 ASSERT3U(ddp->ddp_refcnt, >, 0);
1013
1014                 ddt_phys_addref(ddp);
1015                 result = B_TRUE;
1016         } else {
1017                 /*
1018                  * At the time of implementating this if the block has the
1019                  * DEDUP flag set it must exist in the DEDUP table, but
1020                  * there are many advocates that want ability to remove
1021                  * entries from DDT with refcnt=1. If this will happen,
1022                  * we may have a block with the DEDUP set, but which doesn't
1023                  * have a corresponding entry in the DDT. Be ready.
1024                  */
1025                 ASSERT3S(dde->dde_class, ==, DDT_CLASSES);
1026                 ddt_remove(ddt, dde);
1027                 result = B_FALSE;
1028         }
1029
1030         ddt_exit(ddt);
1031         spa_config_exit(spa, SCL_ZIO, FTAG);
1032
1033         return (result);
1034 }
1035
1036 ZFS_MODULE_PARAM(zfs_dedup, zfs_dedup_, prefetch, INT, ZMOD_RW,
1037         "Enable prefetching dedup-ed blks");