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 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 /*
  23  * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
  25  */
  26
  27 #include <sys/zfs_context.h>
  28 #include <sys/spa.h>
  29 #include <sys/spa_impl.h>
  30 #include <sys/zio.h>
  31 #include <sys/ddt.h>
  32 #include <sys/zap.h>
  33 #include <sys/dmu_tx.h>
  34 #include <sys/arc.h>
  35 #include <sys/dsl_pool.h>
  36 #include <sys/zio_checksum.h>
  37 #include <sys/zio_compress.h>
  38 #include <sys/dsl_scan.h>
  39
  40 static kmem_cache_t *ddt_cache;
  41 static kmem_cache_t *ddt_entry_cache;
  42
  43 /*
  44  * Enable/disable prefetching of dedup-ed blocks which are going to be freed.
  45  */
  46 int zfs_dedup_prefetch = 0;
  47
  48 static const ddt_ops_t *ddt_ops[DDT_TYPES] = {
  49         &ddt_zap_ops,
  50 };
  51
  52 static const char *ddt_class_name[DDT_CLASSES] = {
  53         "ditto",
  54         "duplicate",
  55         "unique",
  56 };
  57
  58 static void
  59 ddt_object_create(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
  60     dmu_tx_t *tx)
  61 {
  62         spa_t *spa = ddt->ddt_spa;
  63         objset_t *os = ddt->ddt_os;
  64         uint64_t *objectp = &ddt->ddt_object[type][class];
  65         boolean_t prehash = zio_checksum_table[ddt->ddt_checksum].ci_flags &
  66             ZCHECKSUM_FLAG_DEDUP;
  67         char name[DDT_NAMELEN];
  68
  69         ddt_object_name(ddt, type, class, name);
  70
  71         ASSERT(*objectp == 0);
  72         VERIFY(ddt_ops[type]->ddt_op_create(os, objectp, tx, prehash) == 0);
  73         ASSERT(*objectp != 0);
  74
  75         VERIFY(zap_add(os, DMU_POOL_DIRECTORY_OBJECT, name,
  76             sizeof (uint64_t), 1, objectp, tx) == 0);
  77
  78         VERIFY(zap_add(os, spa->spa_ddt_stat_object, name,
  79             sizeof (uint64_t), sizeof (ddt_histogram_t) / sizeof (uint64_t),
  80             &ddt->ddt_histogram[type][class], tx) == 0);
  81 }
  82
  83 static void
  84 ddt_object_destroy(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
  85     dmu_tx_t *tx)
  86 {
  87         spa_t *spa = ddt->ddt_spa;
  88         objset_t *os = ddt->ddt_os;
  89         uint64_t *objectp = &ddt->ddt_object[type][class];
  90         uint64_t count;
  91         char name[DDT_NAMELEN];
  92
  93         ddt_object_name(ddt, type, class, name);
  94
  95         ASSERT(*objectp != 0);
  96         ASSERT(ddt_histogram_empty(&ddt->ddt_histogram[type][class]));
  97         VERIFY(ddt_object_count(ddt, type, class, &count) == 0 && count == 0);
  98         VERIFY(zap_remove(os, DMU_POOL_DIRECTORY_OBJECT, name, tx) == 0);
  99         VERIFY(zap_remove(os, spa->spa_ddt_stat_object, name, tx) == 0);
 100         VERIFY(ddt_ops[type]->ddt_op_destroy(os, *objectp, tx) == 0);
 101         bzero(&ddt->ddt_object_stats[type][class], sizeof (ddt_object_t));
 102
 103         *objectp = 0;
 104 }
 105
 106 static int
 107 ddt_object_load(ddt_t *ddt, enum ddt_type type, enum ddt_class class)
 108 {
 109         ddt_object_t *ddo = &ddt->ddt_object_stats[type][class];
 110         dmu_object_info_t doi;
 111         uint64_t count;
 112         char name[DDT_NAMELEN];
 113         int error;
 114
 115         ddt_object_name(ddt, type, class, name);
 116
 117         error = zap_lookup(ddt->ddt_os, DMU_POOL_DIRECTORY_OBJECT, name,
 118             sizeof (uint64_t), 1, &ddt->ddt_object[type][class]);
 119         if (error != 0)
 120                 return (error);
 121
 122         error = zap_lookup(ddt->ddt_os, ddt->ddt_spa->spa_ddt_stat_object, name,
 123             sizeof (uint64_t), sizeof (ddt_histogram_t) / sizeof (uint64_t),
 124             &ddt->ddt_histogram[type][class]);
 125         if (error != 0)
 126                 return (error);
 127
 128         /*
 129          * Seed the cached statistics.
 130          */
 131         error = ddt_object_info(ddt, type, class, &doi);
 132         if (error)
 133                 return (error);
 134
 135         error = ddt_object_count(ddt, type, class, &count);
 136         if (error)
 137                 return (error);
 138
 139         ddo->ddo_count = count;
 140         ddo->ddo_dspace = doi.doi_physical_blocks_512 << 9;
 141         ddo->ddo_mspace = doi.doi_fill_count * doi.doi_data_block_size;
 142
 143         return (0);
 144 }
 145
 146 static void
 147 ddt_object_sync(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 148     dmu_tx_t *tx)
 149 {
 150         ddt_object_t *ddo = &ddt->ddt_object_stats[type][class];
 151         dmu_object_info_t doi;
 152         uint64_t count;
 153         char name[DDT_NAMELEN];
 154
 155         ddt_object_name(ddt, type, class, name);
 156
 157         VERIFY(zap_update(ddt->ddt_os, ddt->ddt_spa->spa_ddt_stat_object, name,
 158             sizeof (uint64_t), sizeof (ddt_histogram_t) / sizeof (uint64_t),
 159             &ddt->ddt_histogram[type][class], tx) == 0);
 160
 161         /*
 162          * Cache DDT statistics; this is the only time they'll change.
 163          */
 164         VERIFY(ddt_object_info(ddt, type, class, &doi) == 0);
 165         VERIFY(ddt_object_count(ddt, type, class, &count) == 0);
 166
 167         ddo->ddo_count = count;
 168         ddo->ddo_dspace = doi.doi_physical_blocks_512 << 9;
 169         ddo->ddo_mspace = doi.doi_fill_count * doi.doi_data_block_size;
 170 }
 171
 172 static int
 173 ddt_object_lookup(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 174     ddt_entry_t *dde)
 175 {
 176         if (!ddt_object_exists(ddt, type, class))
 177                 return (SET_ERROR(ENOENT));
 178
 179         return (ddt_ops[type]->ddt_op_lookup(ddt->ddt_os,
 180             ddt->ddt_object[type][class], dde));
 181 }
 182
 183 static void
 184 ddt_object_prefetch(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 185     ddt_entry_t *dde)
 186 {
 187         if (!ddt_object_exists(ddt, type, class))
 188                 return;
 189
 190         ddt_ops[type]->ddt_op_prefetch(ddt->ddt_os,
 191             ddt->ddt_object[type][class], dde);
 192 }
 193
 194 int
 195 ddt_object_update(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 196     ddt_entry_t *dde, dmu_tx_t *tx)
 197 {
 198         ASSERT(ddt_object_exists(ddt, type, class));
 199
 200         return (ddt_ops[type]->ddt_op_update(ddt->ddt_os,
 201             ddt->ddt_object[type][class], dde, tx));
 202 }
 203
 204 static int
 205 ddt_object_remove(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 206     ddt_entry_t *dde, dmu_tx_t *tx)
 207 {
 208         ASSERT(ddt_object_exists(ddt, type, class));
 209
 210         return (ddt_ops[type]->ddt_op_remove(ddt->ddt_os,
 211             ddt->ddt_object[type][class], dde, tx));
 212 }
 213
 214 int
 215 ddt_object_walk(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 216     uint64_t *walk, ddt_entry_t *dde)
 217 {
 218         ASSERT(ddt_object_exists(ddt, type, class));
 219
 220         return (ddt_ops[type]->ddt_op_walk(ddt->ddt_os,
 221             ddt->ddt_object[type][class], dde, walk));
 222 }
 223
 224 int
 225 ddt_object_count(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 226     uint64_t *count)
 227 {
 228         ASSERT(ddt_object_exists(ddt, type, class));
 229
 230         return (ddt_ops[type]->ddt_op_count(ddt->ddt_os,
 231             ddt->ddt_object[type][class], count));
 232 }
 233
 234 int
 235 ddt_object_info(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 236     dmu_object_info_t *doi)
 237 {
 238         if (!ddt_object_exists(ddt, type, class))
 239                 return (SET_ERROR(ENOENT));
 240
 241         return (dmu_object_info(ddt->ddt_os, ddt->ddt_object[type][class],
 242             doi));
 243 }
 244
 245 boolean_t
 246 ddt_object_exists(ddt_t *ddt, enum ddt_type type, enum ddt_class class)
 247 {
 248         return (!!ddt->ddt_object[type][class]);
 249 }
 250
 251 void
 252 ddt_object_name(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
 253     char *name)
 254 {
 255         (void) sprintf(name, DMU_POOL_DDT,
 256             zio_checksum_table[ddt->ddt_checksum].ci_name,
 257             ddt_ops[type]->ddt_op_name, ddt_class_name[class]);
 258 }
 259
 260 void
 261 ddt_bp_fill(const ddt_phys_t *ddp, blkptr_t *bp, uint64_t txg)
 262 {
 263         int d;
 264         ASSERT(txg != 0);
 265
 266         for (d = 0; d < SPA_DVAS_PER_BP; d++)
 267                 bp->blk_dva[d] = ddp->ddp_dva[d];
 268         BP_SET_BIRTH(bp, txg, ddp->ddp_phys_birth);
 269 }
 270
 271 void
 272 ddt_bp_create(enum zio_checksum checksum,
 273     const ddt_key_t *ddk, const ddt_phys_t *ddp, blkptr_t *bp)
 274 {
 275         BP_ZERO(bp);
 276
 277         if (ddp != NULL)
 278                 ddt_bp_fill(ddp, bp, ddp->ddp_phys_birth);
 279
 280         bp->blk_cksum = ddk->ddk_cksum;
 281         bp->blk_fill = 1;
 282
 283         BP_SET_LSIZE(bp, DDK_GET_LSIZE(ddk));
 284         BP_SET_PSIZE(bp, DDK_GET_PSIZE(ddk));
 285         BP_SET_COMPRESS(bp, DDK_GET_COMPRESS(ddk));
 286         BP_SET_CHECKSUM(bp, checksum);
 287         BP_SET_TYPE(bp, DMU_OT_DEDUP);
 288         BP_SET_LEVEL(bp, 0);
 289         BP_SET_DEDUP(bp, 0);
 290         BP_SET_BYTEORDER(bp, ZFS_HOST_BYTEORDER);
 291 }
 292
 293 void
 294 ddt_key_fill(ddt_key_t *ddk, const blkptr_t *bp)
 295 {
 296         ddk->ddk_cksum = bp->blk_cksum;
 297         ddk->ddk_prop = 0;
 298
 299         DDK_SET_LSIZE(ddk, BP_GET_LSIZE(bp));
 300         DDK_SET_PSIZE(ddk, BP_GET_PSIZE(bp));
 301         DDK_SET_COMPRESS(ddk, BP_GET_COMPRESS(bp));
 302 }
 303
 304 void
 305 ddt_phys_fill(ddt_phys_t *ddp, const blkptr_t *bp)
 306 {
 307         int d;
 308         ASSERT(ddp->ddp_phys_birth == 0);
 309
 310         for (d = 0; d < SPA_DVAS_PER_BP; d++)
 311                 ddp->ddp_dva[d] = bp->blk_dva[d];
 312         ddp->ddp_phys_birth = BP_PHYSICAL_BIRTH(bp);
 313 }
 314
 315 void
 316 ddt_phys_clear(ddt_phys_t *ddp)
 317 {
 318         bzero(ddp, sizeof (*ddp));
 319 }
 320
 321 void
 322 ddt_phys_addref(ddt_phys_t *ddp)
 323 {
 324         ddp->ddp_refcnt++;
 325 }
 326
 327 void
 328 ddt_phys_decref(ddt_phys_t *ddp)
 329 {
 330         if (ddp) {
 331                 ASSERT(ddp->ddp_refcnt > 0);
 332                 ddp->ddp_refcnt--;
 333         }
 334 }
 335
 336 void
 337 ddt_phys_free(ddt_t *ddt, ddt_key_t *ddk, ddt_phys_t *ddp, uint64_t txg)
 338 {
 339         blkptr_t blk;
 340
 341         ddt_bp_create(ddt->ddt_checksum, ddk, ddp, &blk);
 342         ddt_phys_clear(ddp);
 343         zio_free(ddt->ddt_spa, txg, &blk);
 344 }
 345
 346 ddt_phys_t *
 347 ddt_phys_select(const ddt_entry_t *dde, const blkptr_t *bp)
 348 {
 349         ddt_phys_t *ddp = (ddt_phys_t *)dde->dde_phys;
 350         int p;
 351
 352         for (p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
 353                 if (DVA_EQUAL(BP_IDENTITY(bp), &ddp->ddp_dva[0]) &&
 354                     BP_PHYSICAL_BIRTH(bp) == ddp->ddp_phys_birth)
 355                         return (ddp);
 356         }
 357         return (NULL);
 358 }
 359
 360 uint64_t
 361 ddt_phys_total_refcnt(const ddt_entry_t *dde)
 362 {
 363         uint64_t refcnt = 0;
 364         int p;
 365
 366         for (p = DDT_PHYS_SINGLE; p <= DDT_PHYS_TRIPLE; p++)
 367                 refcnt += dde->dde_phys[p].ddp_refcnt;
 368
 369         return (refcnt);
 370 }
 371
 372 static void
 373 ddt_stat_generate(ddt_t *ddt, ddt_entry_t *dde, ddt_stat_t *dds)
 374 {
 375         spa_t *spa = ddt->ddt_spa;
 376         ddt_phys_t *ddp = dde->dde_phys;
 377         ddt_key_t *ddk = &dde->dde_key;
 378         uint64_t lsize = DDK_GET_LSIZE(ddk);
 379         uint64_t psize = DDK_GET_PSIZE(ddk);
 380         int p, d;
 381
 382         bzero(dds, sizeof (*dds));
 383
 384         for (p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
 385                 uint64_t dsize = 0;
 386                 uint64_t refcnt = ddp->ddp_refcnt;
 387
 388                 if (ddp->ddp_phys_birth == 0)
 389                         continue;
 390
 391                 for (d = 0; d < SPA_DVAS_PER_BP; d++)
 392                         dsize += dva_get_dsize_sync(spa, &ddp->ddp_dva[d]);
 393
 394                 dds->dds_blocks += 1;
 395                 dds->dds_lsize += lsize;
 396                 dds->dds_psize += psize;
 397                 dds->dds_dsize += dsize;
 398
 399                 dds->dds_ref_blocks += refcnt;
 400                 dds->dds_ref_lsize += lsize * refcnt;
 401                 dds->dds_ref_psize += psize * refcnt;
 402                 dds->dds_ref_dsize += dsize * refcnt;
 403         }
 404 }
 405
 406 void
 407 ddt_stat_add(ddt_stat_t *dst, const ddt_stat_t *src, uint64_t neg)
 408 {
 409         const uint64_t *s = (const uint64_t *)src;
 410         uint64_t *d = (uint64_t *)dst;
 411         uint64_t *d_end = (uint64_t *)(dst + 1);
 412
 413         ASSERT(neg == 0 || neg == -1ULL);       /* add or subtract */
 414
 415         while (d < d_end)
 416                 *d++ += (*s++ ^ neg) - neg;
 417 }
 418
 419 static void
 420 ddt_stat_update(ddt_t *ddt, ddt_entry_t *dde, uint64_t neg)
 421 {
 422         ddt_stat_t dds;
 423         ddt_histogram_t *ddh;
 424         int bucket;
 425
 426         ddt_stat_generate(ddt, dde, &dds);
 427
 428         bucket = highbit64(dds.dds_ref_blocks) - 1;
 429         ASSERT(bucket >= 0);
 430
 431         ddh = &ddt->ddt_histogram[dde->dde_type][dde->dde_class];
 432
 433         ddt_stat_add(&ddh->ddh_stat[bucket], &dds, neg);
 434 }
 435
 436 void
 437 ddt_histogram_add(ddt_histogram_t *dst, const ddt_histogram_t *src)
 438 {
 439         int h;
 440
 441         for (h = 0; h < 64; h++)
 442                 ddt_stat_add(&dst->ddh_stat[h], &src->ddh_stat[h], 0);
 443 }
 444
 445 void
 446 ddt_histogram_stat(ddt_stat_t *dds, const ddt_histogram_t *ddh)
 447 {
 448         int h;
 449
 450         bzero(dds, sizeof (*dds));
 451
 452         for (h = 0; h < 64; h++)
 453                 ddt_stat_add(dds, &ddh->ddh_stat[h], 0);
 454 }
 455
 456 boolean_t
 457 ddt_histogram_empty(const ddt_histogram_t *ddh)
 458 {
 459         const uint64_t *s = (const uint64_t *)ddh;
 460         const uint64_t *s_end = (const uint64_t *)(ddh + 1);
 461
 462         while (s < s_end)
 463                 if (*s++ != 0)
 464                         return (B_FALSE);
 465
 466         return (B_TRUE);
 467 }
 468
 469 void
 470 ddt_get_dedup_object_stats(spa_t *spa, ddt_object_t *ddo_total)
 471 {
 472         enum zio_checksum c;
 473         enum ddt_type type;
 474         enum ddt_class class;
 475
 476         /* Sum the statistics we cached in ddt_object_sync(). */
 477         for (c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
 478                 ddt_t *ddt = spa->spa_ddt[c];
 479                 for (type = 0; type < DDT_TYPES; type++) {
 480                         for (class = 0; class < DDT_CLASSES;
 481                             class++) {
 482                                 ddt_object_t *ddo =
 483                                     &ddt->ddt_object_stats[type][class];
 484                                 ddo_total->ddo_count += ddo->ddo_count;
 485                                 ddo_total->ddo_dspace += ddo->ddo_dspace;
 486                                 ddo_total->ddo_mspace += ddo->ddo_mspace;
 487                         }
 488                 }
 489         }
 490
 491         /* ... and compute the averages. */
 492         if (ddo_total->ddo_count != 0) {
 493                 ddo_total->ddo_dspace /= ddo_total->ddo_count;
 494                 ddo_total->ddo_mspace /= ddo_total->ddo_count;
 495         }
 496 }
 497
 498 void
 499 ddt_get_dedup_histogram(spa_t *spa, ddt_histogram_t *ddh)
 500 {
 501         enum zio_checksum c;
 502         enum ddt_type type;
 503         enum ddt_class class;
 504
 505         for (c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
 506                 ddt_t *ddt = spa->spa_ddt[c];
 507                 for (type = 0; type < DDT_TYPES; type++) {
 508                         for (class = 0; class < DDT_CLASSES;
 509                             class++) {
 510                                 ddt_histogram_add(ddh,
 511                                     &ddt->ddt_histogram_cache[type][class]);
 512                         }
 513                 }
 514         }
 515 }
 516
 517 void
 518 ddt_get_dedup_stats(spa_t *spa, ddt_stat_t *dds_total)
 519 {
 520         ddt_histogram_t *ddh_total;
 521
 522         ddh_total = kmem_zalloc(sizeof (ddt_histogram_t), KM_SLEEP);
 523         ddt_get_dedup_histogram(spa, ddh_total);
 524         ddt_histogram_stat(dds_total, ddh_total);
 525         kmem_free(ddh_total, sizeof (ddt_histogram_t));
 526 }
 527
 528 uint64_t
 529 ddt_get_dedup_dspace(spa_t *spa)
 530 {
 531         ddt_stat_t dds_total = { 0 };
 532
 533         ddt_get_dedup_stats(spa, &dds_total);
 534         return (dds_total.dds_ref_dsize - dds_total.dds_dsize);
 535 }
 536
 537 uint64_t
 538 ddt_get_pool_dedup_ratio(spa_t *spa)
 539 {
 540         ddt_stat_t dds_total = { 0 };
 541
 542         ddt_get_dedup_stats(spa, &dds_total);
 543         if (dds_total.dds_dsize == 0)
 544                 return (100);
 545
 546         return (dds_total.dds_ref_dsize * 100 / dds_total.dds_dsize);
 547 }
 548
 549 int
 550 ddt_ditto_copies_needed(ddt_t *ddt, ddt_entry_t *dde, ddt_phys_t *ddp_willref)
 551 {
 552         spa_t *spa = ddt->ddt_spa;
 553         uint64_t total_refcnt = 0;
 554         uint64_t ditto = spa->spa_dedup_ditto;
 555         int total_copies = 0;
 556         int desired_copies = 0;
 557         int p;
 558
 559         for (p = DDT_PHYS_SINGLE; p <= DDT_PHYS_TRIPLE; p++) {
 560                 ddt_phys_t *ddp = &dde->dde_phys[p];
 561                 zio_t *zio = dde->dde_lead_zio[p];
 562                 uint64_t refcnt = ddp->ddp_refcnt;      /* committed refs */
 563                 if (zio != NULL)
 564                         refcnt += zio->io_parent_count; /* pending refs */
 565                 if (ddp == ddp_willref)
 566                         refcnt++;                       /* caller's ref */
 567                 if (refcnt != 0) {
 568                         total_refcnt += refcnt;
 569                         total_copies += p;
 570                 }
 571         }
 572
 573         if (ditto == 0 || ditto > UINT32_MAX)
 574                 ditto = UINT32_MAX;
 575
 576         if (total_refcnt >= 1)
 577                 desired_copies++;
 578         if (total_refcnt >= ditto)
 579                 desired_copies++;
 580         if (total_refcnt >= ditto * ditto)
 581                 desired_copies++;
 582
 583         return (MAX(desired_copies, total_copies) - total_copies);
 584 }
 585
 586 int
 587 ddt_ditto_copies_present(ddt_entry_t *dde)
 588 {
 589         ddt_phys_t *ddp = &dde->dde_phys[DDT_PHYS_DITTO];
 590         dva_t *dva = ddp->ddp_dva;
 591         int copies = 0 - DVA_GET_GANG(dva);
 592         int d;
 593
 594         for (d = 0; d < SPA_DVAS_PER_BP; d++, dva++)
 595                 if (DVA_IS_VALID(dva))
 596                         copies++;
 597
 598         ASSERT(copies >= 0 && copies < SPA_DVAS_PER_BP);
 599
 600         return (copies);
 601 }
 602
 603 size_t
 604 ddt_compress(void *src, uchar_t *dst, size_t s_len, size_t d_len)
 605 {
 606         uchar_t *version = dst++;
 607         int cpfunc = ZIO_COMPRESS_ZLE;
 608         zio_compress_info_t *ci = &zio_compress_table[cpfunc];
 609         size_t c_len;
 610
 611         ASSERT(d_len >= s_len + 1);     /* no compression plus version byte */
 612
 613         c_len = ci->ci_compress(src, dst, s_len, d_len - 1, ci->ci_level);
 614
 615         if (c_len == s_len) {
 616                 cpfunc = ZIO_COMPRESS_OFF;
 617                 bcopy(src, dst, s_len);
 618         }
 619
 620         *version = cpfunc;
 621         /* CONSTCOND */
 622         if (ZFS_HOST_BYTEORDER)
 623                 *version |= DDT_COMPRESS_BYTEORDER_MASK;
 624
 625         return (c_len + 1);
 626 }
 627
 628 void
 629 ddt_decompress(uchar_t *src, void *dst, size_t s_len, size_t d_len)
 630 {
 631         uchar_t version = *src++;
 632         int cpfunc = version & DDT_COMPRESS_FUNCTION_MASK;
 633         zio_compress_info_t *ci = &zio_compress_table[cpfunc];
 634
 635         if (ci->ci_decompress != NULL)
 636                 (void) ci->ci_decompress(src, dst, s_len, d_len, ci->ci_level);
 637         else
 638                 bcopy(src, dst, d_len);
 639
 640         if (((version & DDT_COMPRESS_BYTEORDER_MASK) != 0) !=
 641             (ZFS_HOST_BYTEORDER != 0))
 642                 byteswap_uint64_array(dst, d_len);
 643 }
 644
 645 ddt_t *
 646 ddt_select_by_checksum(spa_t *spa, enum zio_checksum c)
 647 {
 648         return (spa->spa_ddt[c]);
 649 }
 650
 651 ddt_t *
 652 ddt_select(spa_t *spa, const blkptr_t *bp)
 653 {
 654         return (spa->spa_ddt[BP_GET_CHECKSUM(bp)]);
 655 }
 656
 657 void
 658 ddt_enter(ddt_t *ddt)
 659 {
 660         mutex_enter(&ddt->ddt_lock);
 661 }
 662
 663 void
 664 ddt_exit(ddt_t *ddt)
 665 {
 666         mutex_exit(&ddt->ddt_lock);
 667 }
 668
 669 void
 670 ddt_init(void)
 671 {
 672         ddt_cache = kmem_cache_create("ddt_cache",
 673             sizeof (ddt_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
 674         ddt_entry_cache = kmem_cache_create("ddt_entry_cache",
 675             sizeof (ddt_entry_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
 676 }
 677
 678 void
 679 ddt_fini(void)
 680 {
 681         kmem_cache_destroy(ddt_entry_cache);
 682         kmem_cache_destroy(ddt_cache);
 683 }
 684
 685 static ddt_entry_t *
 686 ddt_alloc(const ddt_key_t *ddk)
 687 {
 688         ddt_entry_t *dde;
 689
 690         dde = kmem_cache_alloc(ddt_entry_cache, KM_SLEEP);
 691         bzero(dde, sizeof (ddt_entry_t));
 692         cv_init(&dde->dde_cv, NULL, CV_DEFAULT, NULL);
 693
 694         dde->dde_key = *ddk;
 695
 696         return (dde);
 697 }
 698
 699 static void
 700 ddt_free(ddt_entry_t *dde)
 701 {
 702         int p;
 703
 704         ASSERT(!dde->dde_loading);
 705
 706         for (p = 0; p < DDT_PHYS_TYPES; p++)
 707                 ASSERT(dde->dde_lead_zio[p] == NULL);
 708
 709         if (dde->dde_repair_data != NULL)
 710                 zio_buf_free(dde->dde_repair_data,
 711                     DDK_GET_PSIZE(&dde->dde_key));
 712
 713         cv_destroy(&dde->dde_cv);
 714         kmem_cache_free(ddt_entry_cache, dde);
 715 }
 716
 717 void
 718 ddt_remove(ddt_t *ddt, ddt_entry_t *dde)
 719 {
 720         ASSERT(MUTEX_HELD(&ddt->ddt_lock));
 721
 722         avl_remove(&ddt->ddt_tree, dde);
 723         ddt_free(dde);
 724 }
 725
 726 ddt_entry_t *
 727 ddt_lookup(ddt_t *ddt, const blkptr_t *bp, boolean_t add)
 728 {
 729         ddt_entry_t *dde, dde_search;
 730         enum ddt_type type;
 731         enum ddt_class class;
 732         avl_index_t where;
 733         int error;
 734
 735         ASSERT(MUTEX_HELD(&ddt->ddt_lock));
 736
 737         ddt_key_fill(&dde_search.dde_key, bp);
 738
 739         dde = avl_find(&ddt->ddt_tree, &dde_search, &where);
 740         if (dde == NULL) {
 741                 if (!add)
 742                         return (NULL);
 743                 dde = ddt_alloc(&dde_search.dde_key);
 744                 avl_insert(&ddt->ddt_tree, dde, where);
 745         }
 746
 747         while (dde->dde_loading)
 748                 cv_wait(&dde->dde_cv, &ddt->ddt_lock);
 749
 750         if (dde->dde_loaded)
 751                 return (dde);
 752
 753         dde->dde_loading = B_TRUE;
 754
 755         ddt_exit(ddt);
 756
 757         error = ENOENT;
 758
 759         for (type = 0; type < DDT_TYPES; type++) {
 760                 for (class = 0; class < DDT_CLASSES; class++) {
 761                         error = ddt_object_lookup(ddt, type, class, dde);
 762                         if (error != ENOENT)
 763                                 break;
 764                 }
 765                 if (error != ENOENT)
 766                         break;
 767         }
 768
 769         ASSERT(error == 0 || error == ENOENT);
 770
 771         ddt_enter(ddt);
 772
 773         ASSERT(dde->dde_loaded == B_FALSE);
 774         ASSERT(dde->dde_loading == B_TRUE);
 775
 776         dde->dde_type = type;   /* will be DDT_TYPES if no entry found */
 777         dde->dde_class = class; /* will be DDT_CLASSES if no entry found */
 778         dde->dde_loaded = B_TRUE;
 779         dde->dde_loading = B_FALSE;
 780
 781         if (error == 0)
 782                 ddt_stat_update(ddt, dde, -1ULL);
 783
 784         cv_broadcast(&dde->dde_cv);
 785
 786         return (dde);
 787 }
 788
 789 void
 790 ddt_prefetch(spa_t *spa, const blkptr_t *bp)
 791 {
 792         ddt_t *ddt;
 793         ddt_entry_t dde;
 794         enum ddt_type type;
 795         enum ddt_class class;
 796
 797         if (!zfs_dedup_prefetch || bp == NULL || !BP_GET_DEDUP(bp))
 798                 return;
 799
 800         /*
 801          * We only remove the DDT once all tables are empty and only
 802          * prefetch dedup blocks when there are entries in the DDT.
 803          * Thus no locking is required as the DDT can't disappear on us.
 804          */
 805         ddt = ddt_select(spa, bp);
 806         ddt_key_fill(&dde.dde_key, bp);
 807
 808         for (type = 0; type < DDT_TYPES; type++) {
 809                 for (class = 0; class < DDT_CLASSES; class++) {
 810                         ddt_object_prefetch(ddt, type, class, &dde);
 811                 }
 812         }
 813 }
 814
 815 /*
 816  * Opaque struct used for ddt_key comparison
 817  */
 818 #define DDT_KEY_CMP_LEN (sizeof (ddt_key_t) / sizeof (uint16_t))
 819
 820 typedef struct ddt_key_cmp {
 821         uint16_t        u16[DDT_KEY_CMP_LEN];
 822 } ddt_key_cmp_t;
 823
 824 int
 825 ddt_entry_compare(const void *x1, const void *x2)
 826 {
 827         const ddt_entry_t *dde1 = x1;
 828         const ddt_entry_t *dde2 = x2;
 829         const ddt_key_cmp_t *k1 = (const ddt_key_cmp_t *)&dde1->dde_key;
 830         const ddt_key_cmp_t *k2 = (const ddt_key_cmp_t *)&dde2->dde_key;
 831         int32_t cmp = 0;
 832         int i;
 833
 834         for (i = 0; i < DDT_KEY_CMP_LEN; i++) {
 835                 cmp = (int32_t)k1->u16[i] - (int32_t)k2->u16[i];
 836                 if (likely(cmp))
 837                         break;
 838         }
 839
 840         return (AVL_ISIGN(cmp));
 841 }
 842
 843 static ddt_t *
 844 ddt_table_alloc(spa_t *spa, enum zio_checksum c)
 845 {
 846         ddt_t *ddt;
 847
 848         ddt = kmem_cache_alloc(ddt_cache, KM_SLEEP);
 849         bzero(ddt, sizeof (ddt_t));
 850
 851         mutex_init(&ddt->ddt_lock, NULL, MUTEX_DEFAULT, NULL);
 852         avl_create(&ddt->ddt_tree, ddt_entry_compare,
 853             sizeof (ddt_entry_t), offsetof(ddt_entry_t, dde_node));
 854         avl_create(&ddt->ddt_repair_tree, ddt_entry_compare,
 855             sizeof (ddt_entry_t), offsetof(ddt_entry_t, dde_node));
 856         ddt->ddt_checksum = c;
 857         ddt->ddt_spa = spa;
 858         ddt->ddt_os = spa->spa_meta_objset;
 859
 860         return (ddt);
 861 }
 862
 863 static void
 864 ddt_table_free(ddt_t *ddt)
 865 {
 866         ASSERT(avl_numnodes(&ddt->ddt_tree) == 0);
 867         ASSERT(avl_numnodes(&ddt->ddt_repair_tree) == 0);
 868         avl_destroy(&ddt->ddt_tree);
 869         avl_destroy(&ddt->ddt_repair_tree);
 870         mutex_destroy(&ddt->ddt_lock);
 871         kmem_cache_free(ddt_cache, ddt);
 872 }
 873
 874 void
 875 ddt_create(spa_t *spa)
 876 {
 877         enum zio_checksum c;
 878
 879         spa->spa_dedup_checksum = ZIO_DEDUPCHECKSUM;
 880
 881         for (c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++)
 882                 spa->spa_ddt[c] = ddt_table_alloc(spa, c);
 883 }
 884
 885 int
 886 ddt_load(spa_t *spa)
 887 {
 888         enum zio_checksum c;
 889         enum ddt_type type;
 890         enum ddt_class class;
 891         int error;
 892
 893         ddt_create(spa);
 894
 895         error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 896             DMU_POOL_DDT_STATS, sizeof (uint64_t), 1,
 897             &spa->spa_ddt_stat_object);
 898
 899         if (error)
 900                 return (error == ENOENT ? 0 : error);
 901
 902         for (c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
 903                 ddt_t *ddt = spa->spa_ddt[c];
 904                 for (type = 0; type < DDT_TYPES; type++) {
 905                         for (class = 0; class < DDT_CLASSES;
 906                             class++) {
 907                                 error = ddt_object_load(ddt, type, class);
 908                                 if (error != 0 && error != ENOENT)
 909                                         return (error);
 910                         }
 911                 }
 912
 913                 /*
 914                  * Seed the cached histograms.
 915                  */
 916                 bcopy(ddt->ddt_histogram, &ddt->ddt_histogram_cache,
 917                     sizeof (ddt->ddt_histogram));
 918         }
 919
 920         return (0);
 921 }
 922
 923 void
 924 ddt_unload(spa_t *spa)
 925 {
 926         enum zio_checksum c;
 927
 928         for (c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
 929                 if (spa->spa_ddt[c]) {
 930                         ddt_table_free(spa->spa_ddt[c]);
 931                         spa->spa_ddt[c] = NULL;
 932                 }
 933         }
 934 }
 935
 936 boolean_t
 937 ddt_class_contains(spa_t *spa, enum ddt_class max_class, const blkptr_t *bp)
 938 {
 939         ddt_t *ddt;
 940         ddt_entry_t *dde;
 941         enum ddt_type type;
 942         enum ddt_class class;
 943
 944         if (!BP_GET_DEDUP(bp))
 945                 return (B_FALSE);
 946
 947         if (max_class == DDT_CLASS_UNIQUE)
 948                 return (B_TRUE);
 949
 950         ddt = spa->spa_ddt[BP_GET_CHECKSUM(bp)];
 951         dde = kmem_cache_alloc(ddt_entry_cache, KM_SLEEP);
 952
 953         ddt_key_fill(&(dde->dde_key), bp);
 954
 955         for (type = 0; type < DDT_TYPES; type++) {
 956                 for (class = 0; class <= max_class; class++) {
 957                         if (ddt_object_lookup(ddt, type, class, dde) == 0) {
 958                                 kmem_cache_free(ddt_entry_cache, dde);
 959                                 return (B_TRUE);
 960                         }
 961                 }
 962         }
 963
 964         kmem_cache_free(ddt_entry_cache, dde);
 965         return (B_FALSE);
 966 }
 967
 968 ddt_entry_t *
 969 ddt_repair_start(ddt_t *ddt, const blkptr_t *bp)
 970 {
 971         ddt_key_t ddk;
 972         ddt_entry_t *dde;
 973         enum ddt_type type;
 974         enum ddt_class class;
 975
 976         ddt_key_fill(&ddk, bp);
 977
 978         dde = ddt_alloc(&ddk);
 979
 980         for (type = 0; type < DDT_TYPES; type++) {
 981                 for (class = 0; class < DDT_CLASSES; class++) {
 982                         /*
 983                          * We can only do repair if there are multiple copies
 984                          * of the block.  For anything in the UNIQUE class,
 985                          * there's definitely only one copy, so don't even try.
 986                          */
 987                         if (class != DDT_CLASS_UNIQUE &&
 988                             ddt_object_lookup(ddt, type, class, dde) == 0)
 989                                 return (dde);
 990                 }
 991         }
 992
 993         bzero(dde->dde_phys, sizeof (dde->dde_phys));
 994
 995         return (dde);
 996 }
 997
 998 void
 999 ddt_repair_done(ddt_t *ddt, ddt_entry_t *dde)
1000 {
1001         avl_index_t where;
1002
1003         ddt_enter(ddt);
1004
1005         if (dde->dde_repair_data != NULL && spa_writeable(ddt->ddt_spa) &&
1006             avl_find(&ddt->ddt_repair_tree, dde, &where) == NULL)
1007                 avl_insert(&ddt->ddt_repair_tree, dde, where);
1008         else
1009                 ddt_free(dde);
1010
1011         ddt_exit(ddt);
1012 }
1013
1014 static void
1015 ddt_repair_entry_done(zio_t *zio)
1016 {
1017         ddt_entry_t *rdde = zio->io_private;
1018
1019         ddt_free(rdde);
1020 }
1021
1022 static void
1023 ddt_repair_entry(ddt_t *ddt, ddt_entry_t *dde, ddt_entry_t *rdde, zio_t *rio)
1024 {
1025         ddt_phys_t *ddp = dde->dde_phys;
1026         ddt_phys_t *rddp = rdde->dde_phys;
1027         ddt_key_t *ddk = &dde->dde_key;
1028         ddt_key_t *rddk = &rdde->dde_key;
1029         zio_t *zio;
1030         blkptr_t blk;
1031         int p;
1032
1033         zio = zio_null(rio, rio->io_spa, NULL,
1034             ddt_repair_entry_done, rdde, rio->io_flags);
1035
1036         for (p = 0; p < DDT_PHYS_TYPES; p++, ddp++, rddp++) {
1037                 if (ddp->ddp_phys_birth == 0 ||
1038                     ddp->ddp_phys_birth != rddp->ddp_phys_birth ||
1039                     bcmp(ddp->ddp_dva, rddp->ddp_dva, sizeof (ddp->ddp_dva)))
1040                         continue;
1041                 ddt_bp_create(ddt->ddt_checksum, ddk, ddp, &blk);
1042                 zio_nowait(zio_rewrite(zio, zio->io_spa, 0, &blk,
1043                     rdde->dde_repair_data, DDK_GET_PSIZE(rddk), NULL, NULL,
1044                     ZIO_PRIORITY_SYNC_WRITE, ZIO_DDT_CHILD_FLAGS(zio), NULL));
1045         }
1046
1047         zio_nowait(zio);
1048 }
1049
1050 static void
1051 ddt_repair_table(ddt_t *ddt, zio_t *rio)
1052 {
1053         spa_t *spa = ddt->ddt_spa;
1054         ddt_entry_t *dde, *rdde_next, *rdde;
1055         avl_tree_t *t = &ddt->ddt_repair_tree;
1056         blkptr_t blk;
1057
1058         if (spa_sync_pass(spa) > 1)
1059                 return;
1060
1061         ddt_enter(ddt);
1062         for (rdde = avl_first(t); rdde != NULL; rdde = rdde_next) {
1063                 rdde_next = AVL_NEXT(t, rdde);
1064                 avl_remove(&ddt->ddt_repair_tree, rdde);
1065                 ddt_exit(ddt);
1066                 ddt_bp_create(ddt->ddt_checksum, &rdde->dde_key, NULL, &blk);
1067                 dde = ddt_repair_start(ddt, &blk);
1068                 ddt_repair_entry(ddt, dde, rdde, rio);
1069                 ddt_repair_done(ddt, dde);
1070                 ddt_enter(ddt);
1071         }
1072         ddt_exit(ddt);
1073 }
1074
1075 static void
1076 ddt_sync_entry(ddt_t *ddt, ddt_entry_t *dde, dmu_tx_t *tx, uint64_t txg)
1077 {
1078         dsl_pool_t *dp = ddt->ddt_spa->spa_dsl_pool;
1079         ddt_phys_t *ddp = dde->dde_phys;
1080         ddt_key_t *ddk = &dde->dde_key;
1081         enum ddt_type otype = dde->dde_type;
1082         enum ddt_type ntype = DDT_TYPE_CURRENT;
1083         enum ddt_class oclass = dde->dde_class;
1084         enum ddt_class nclass;
1085         uint64_t total_refcnt = 0;
1086         int p;
1087
1088         ASSERT(dde->dde_loaded);
1089         ASSERT(!dde->dde_loading);
1090
1091         for (p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
1092                 ASSERT(dde->dde_lead_zio[p] == NULL);
1093                 if (ddp->ddp_phys_birth == 0) {
1094                         ASSERT(ddp->ddp_refcnt == 0);
1095                         continue;
1096                 }
1097                 if (p == DDT_PHYS_DITTO) {
1098                         if (ddt_ditto_copies_needed(ddt, dde, NULL) == 0)
1099                                 ddt_phys_free(ddt, ddk, ddp, txg);
1100                         continue;
1101                 }
1102                 if (ddp->ddp_refcnt == 0)
1103                         ddt_phys_free(ddt, ddk, ddp, txg);
1104                 total_refcnt += ddp->ddp_refcnt;
1105         }
1106
1107         if (dde->dde_phys[DDT_PHYS_DITTO].ddp_phys_birth != 0)
1108                 nclass = DDT_CLASS_DITTO;
1109         else if (total_refcnt > 1)
1110                 nclass = DDT_CLASS_DUPLICATE;
1111         else
1112                 nclass = DDT_CLASS_UNIQUE;
1113
1114         if (otype != DDT_TYPES &&
1115             (otype != ntype || oclass != nclass || total_refcnt == 0)) {
1116                 VERIFY(ddt_object_remove(ddt, otype, oclass, dde, tx) == 0);
1117                 ASSERT(ddt_object_lookup(ddt, otype, oclass, dde) == ENOENT);
1118         }
1119
1120         if (total_refcnt != 0) {
1121                 dde->dde_type = ntype;
1122                 dde->dde_class = nclass;
1123                 ddt_stat_update(ddt, dde, 0);
1124                 if (!ddt_object_exists(ddt, ntype, nclass))
1125                         ddt_object_create(ddt, ntype, nclass, tx);
1126                 VERIFY(ddt_object_update(ddt, ntype, nclass, dde, tx) == 0);
1127
1128                 /*
1129                  * If the class changes, the order that we scan this bp
1130                  * changes.  If it decreases, we could miss it, so
1131                  * scan it right now.  (This covers both class changing
1132                  * while we are doing ddt_walk(), and when we are
1133                  * traversing.)
1134                  */
1135                 if (nclass < oclass) {
1136                         dsl_scan_ddt_entry(dp->dp_scan,
1137                             ddt->ddt_checksum, dde, tx);
1138                 }
1139         }
1140 }
1141
1142 static void
1143 ddt_sync_table(ddt_t *ddt, dmu_tx_t *tx, uint64_t txg)
1144 {
1145         spa_t *spa = ddt->ddt_spa;
1146         ddt_entry_t *dde;
1147         void *cookie = NULL;
1148         enum ddt_type type;
1149         enum ddt_class class;
1150
1151         if (avl_numnodes(&ddt->ddt_tree) == 0)
1152                 return;
1153
1154         ASSERT(spa->spa_uberblock.ub_version >= SPA_VERSION_DEDUP);
1155
1156         if (spa->spa_ddt_stat_object == 0) {
1157                 spa->spa_ddt_stat_object = zap_create_link(ddt->ddt_os,
1158                     DMU_OT_DDT_STATS, DMU_POOL_DIRECTORY_OBJECT,
1159                     DMU_POOL_DDT_STATS, tx);
1160         }
1161
1162         while ((dde = avl_destroy_nodes(&ddt->ddt_tree, &cookie)) != NULL) {
1163                 ddt_sync_entry(ddt, dde, tx, txg);
1164                 ddt_free(dde);
1165         }
1166
1167         for (type = 0; type < DDT_TYPES; type++) {
1168                 uint64_t add, count = 0;
1169                 for (class = 0; class < DDT_CLASSES; class++) {
1170                         if (ddt_object_exists(ddt, type, class)) {
1171                                 ddt_object_sync(ddt, type, class, tx);
1172                                 VERIFY(ddt_object_count(ddt, type, class,
1173                                     &add) == 0);
1174                                 count += add;
1175                         }
1176                 }
1177                 for (class = 0; class < DDT_CLASSES; class++) {
1178                         if (count == 0 && ddt_object_exists(ddt, type, class))
1179                                 ddt_object_destroy(ddt, type, class, tx);
1180                 }
1181         }
1182
1183         bcopy(ddt->ddt_histogram, &ddt->ddt_histogram_cache,
1184             sizeof (ddt->ddt_histogram));
1185 }
1186
1187 void
1188 ddt_sync(spa_t *spa, uint64_t txg)
1189 {
1190         dmu_tx_t *tx;
1191         zio_t *rio = zio_root(spa, NULL, NULL,
1192             ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE);
1193         enum zio_checksum c;
1194
1195         ASSERT(spa_syncing_txg(spa) == txg);
1196
1197         tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
1198
1199         for (c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
1200                 ddt_t *ddt = spa->spa_ddt[c];
1201                 if (ddt == NULL)
1202                         continue;
1203                 ddt_sync_table(ddt, tx, txg);
1204                 ddt_repair_table(ddt, rio);
1205         }
1206
1207         (void) zio_wait(rio);
1208
1209         dmu_tx_commit(tx);
1210 }
1211
1212 int
1213 ddt_walk(spa_t *spa, ddt_bookmark_t *ddb, ddt_entry_t *dde)
1214 {
1215         do {
1216                 do {
1217                         do {
1218                                 ddt_t *ddt = spa->spa_ddt[ddb->ddb_checksum];
1219                                 int error = ENOENT;
1220                                 if (ddt_object_exists(ddt, ddb->ddb_type,
1221                                     ddb->ddb_class)) {
1222                                         error = ddt_object_walk(ddt,
1223                                             ddb->ddb_type, ddb->ddb_class,
1224                                             &ddb->ddb_cursor, dde);
1225                                 }
1226                                 dde->dde_type = ddb->ddb_type;
1227                                 dde->dde_class = ddb->ddb_class;
1228                                 if (error == 0)
1229                                         return (0);
1230                                 if (error != ENOENT)
1231                                         return (error);
1232                                 ddb->ddb_cursor = 0;
1233                         } while (++ddb->ddb_checksum < ZIO_CHECKSUM_FUNCTIONS);
1234                         ddb->ddb_checksum = 0;
1235                 } while (++ddb->ddb_type < DDT_TYPES);
1236                 ddb->ddb_type = 0;
1237         } while (++ddb->ddb_class < DDT_CLASSES);
1238
1239         return (SET_ERROR(ENOENT));
1240 }
1241
1242 #if defined(_KERNEL) && defined(HAVE_SPL)
1243 module_param(zfs_dedup_prefetch, int, 0644);
1244 MODULE_PARM_DESC(zfs_dedup_prefetch, "Enable prefetching dedup-ed blks");
1245 #endif