ddt.c

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    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  */
   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 #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         ASSERT(*objectp == 0);
   73         VERIFY(ddt_ops[type]->ddt_op_create(os, objectp, tx, prehash) == 0);
   74         ASSERT(*objectp != 0);
   75 
   76         VERIFY(zap_add(os, DMU_POOL_DIRECTORY_OBJECT, name,
   77             sizeof (uint64_t), 1, objectp, tx) == 0);
   78 
   79         VERIFY(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) == 0);
   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         ASSERT(*objectp != 0);
   97         ASSERT(ddt_histogram_empty(&ddt->ddt_histogram[type][class]));
   98         VERIFY(ddt_object_count(ddt, type, class, &count) == 0 && count == 0);
   99         VERIFY(zap_remove(os, DMU_POOL_DIRECTORY_OBJECT, name, tx) == 0);
  100         VERIFY(zap_remove(os, spa->spa_ddt_stat_object, name, tx) == 0);
  101         VERIFY(ddt_ops[type]->ddt_op_destroy(os, *objectp, tx) == 0);
  102         memset(&ddt->ddt_object_stats[type][class], 0, sizeof (ddt_object_t));
  103 
  104         *objectp = 0;
  105 }
  106 
  107 static int
  108 ddt_object_load(ddt_t *ddt, enum ddt_type type, enum ddt_class class)
  109 {
  110         ddt_object_t *ddo = &ddt->ddt_object_stats[type][class];
  111         dmu_object_info_t doi;
  112         uint64_t count;
  113         char name[DDT_NAMELEN];
  114         int error;
  115 
  116         ddt_object_name(ddt, type, class, name);
  117 
  118         error = zap_lookup(ddt->ddt_os, DMU_POOL_DIRECTORY_OBJECT, name,
  119             sizeof (uint64_t), 1, &ddt->ddt_object[type][class]);
  120         if (error != 0)
  121                 return (error);
  122 
  123         error = zap_lookup(ddt->ddt_os, ddt->ddt_spa->spa_ddt_stat_object, name,
  124             sizeof (uint64_t), sizeof (ddt_histogram_t) / sizeof (uint64_t),
  125             &ddt->ddt_histogram[type][class]);
  126         if (error != 0)
  127                 return (error);
  128 
  129         /*
  130          * Seed the cached statistics.
  131          */
  132         error = ddt_object_info(ddt, type, class, &doi);
  133         if (error)
  134                 return (error);
  135 
  136         error = ddt_object_count(ddt, type, class, &count);
  137         if (error)
  138                 return (error);
  139 
  140         ddo->ddo_count = count;
  141         ddo->ddo_dspace = doi.doi_physical_blocks_512 << 9;
  142         ddo->ddo_mspace = doi.doi_fill_count * doi.doi_data_block_size;
  143 
  144         return (0);
  145 }
  146 
  147 static void
  148 ddt_object_sync(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
  149     dmu_tx_t *tx)
  150 {
  151         ddt_object_t *ddo = &ddt->ddt_object_stats[type][class];
  152         dmu_object_info_t doi;
  153         uint64_t count;
  154         char name[DDT_NAMELEN];
  155 
  156         ddt_object_name(ddt, type, class, name);
  157 
  158         VERIFY(zap_update(ddt->ddt_os, ddt->ddt_spa->spa_ddt_stat_object, name,
  159             sizeof (uint64_t), sizeof (ddt_histogram_t) / sizeof (uint64_t),
  160             &ddt->ddt_histogram[type][class], tx) == 0);
  161 
  162         /*
  163          * Cache DDT statistics; this is the only time they'll change.
  164          */
  165         VERIFY(ddt_object_info(ddt, type, class, &doi) == 0);
  166         VERIFY(ddt_object_count(ddt, type, class, &count) == 0);
  167 
  168         ddo->ddo_count = count;
  169         ddo->ddo_dspace = doi.doi_physical_blocks_512 << 9;
  170         ddo->ddo_mspace = doi.doi_fill_count * doi.doi_data_block_size;
  171 }
  172 
  173 static int
  174 ddt_object_lookup(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
  175     ddt_entry_t *dde)
  176 {
  177         if (!ddt_object_exists(ddt, type, class))
  178                 return (SET_ERROR(ENOENT));
  179 
  180         return (ddt_ops[type]->ddt_op_lookup(ddt->ddt_os,
  181             ddt->ddt_object[type][class], dde));
  182 }
  183 
  184 static void
  185 ddt_object_prefetch(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
  186     ddt_entry_t *dde)
  187 {
  188         if (!ddt_object_exists(ddt, type, class))
  189                 return;
  190 
  191         ddt_ops[type]->ddt_op_prefetch(ddt->ddt_os,
  192             ddt->ddt_object[type][class], dde);
  193 }
  194 
  195 int
  196 ddt_object_update(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
  197     ddt_entry_t *dde, dmu_tx_t *tx)
  198 {
  199         ASSERT(ddt_object_exists(ddt, type, class));
  200 
  201         return (ddt_ops[type]->ddt_op_update(ddt->ddt_os,
  202             ddt->ddt_object[type][class], dde, tx));
  203 }
  204 
  205 static int
  206 ddt_object_remove(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
  207     ddt_entry_t *dde, dmu_tx_t *tx)
  208 {
  209         ASSERT(ddt_object_exists(ddt, type, class));
  210 
  211         return (ddt_ops[type]->ddt_op_remove(ddt->ddt_os,
  212             ddt->ddt_object[type][class], dde, tx));
  213 }
  214 
  215 int
  216 ddt_object_walk(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
  217     uint64_t *walk, ddt_entry_t *dde)
  218 {
  219         ASSERT(ddt_object_exists(ddt, type, class));
  220 
  221         return (ddt_ops[type]->ddt_op_walk(ddt->ddt_os,
  222             ddt->ddt_object[type][class], dde, walk));
  223 }
  224 
  225 int
  226 ddt_object_count(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
  227     uint64_t *count)
  228 {
  229         ASSERT(ddt_object_exists(ddt, type, class));
  230 
  231         return (ddt_ops[type]->ddt_op_count(ddt->ddt_os,
  232             ddt->ddt_object[type][class], count));
  233 }
  234 
  235 int
  236 ddt_object_info(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
  237     dmu_object_info_t *doi)
  238 {
  239         if (!ddt_object_exists(ddt, type, class))
  240                 return (SET_ERROR(ENOENT));
  241 
  242         return (dmu_object_info(ddt->ddt_os, ddt->ddt_object[type][class],
  243             doi));
  244 }
  245 
  246 boolean_t
  247 ddt_object_exists(ddt_t *ddt, enum ddt_type type, enum ddt_class class)
  248 {
  249         return (!!ddt->ddt_object[type][class]);
  250 }
  251 
  252 void
  253 ddt_object_name(ddt_t *ddt, enum ddt_type type, enum ddt_class class,
  254     char *name)
  255 {
  256         (void) snprintf(name, DDT_NAMELEN, DMU_POOL_DDT,
  257             zio_checksum_table[ddt->ddt_checksum].ci_name,
  258             ddt_ops[type]->ddt_op_name, ddt_class_name[class]);
  259 }
  260 
  261 void
  262 ddt_bp_fill(const ddt_phys_t *ddp, blkptr_t *bp, uint64_t txg)
  263 {
  264         ASSERT(txg != 0);
  265 
  266         for (int 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 /*
  272  * The bp created via this function may be used for repairs and scrub, but it
  273  * will be missing the salt / IV required to do a full decrypting read.
  274  */
  275 void
  276 ddt_bp_create(enum zio_checksum checksum,
  277     const ddt_key_t *ddk, const ddt_phys_t *ddp, blkptr_t *bp)
  278 {
  279         BP_ZERO(bp);
  280 
  281         if (ddp != NULL)
  282                 ddt_bp_fill(ddp, bp, ddp->ddp_phys_birth);
  283 
  284         bp->blk_cksum = ddk->ddk_cksum;
  285 
  286         BP_SET_LSIZE(bp, DDK_GET_LSIZE(ddk));
  287         BP_SET_PSIZE(bp, DDK_GET_PSIZE(ddk));
  288         BP_SET_COMPRESS(bp, DDK_GET_COMPRESS(ddk));
  289         BP_SET_CRYPT(bp, DDK_GET_CRYPT(ddk));
  290         BP_SET_FILL(bp, 1);
  291         BP_SET_CHECKSUM(bp, checksum);
  292         BP_SET_TYPE(bp, DMU_OT_DEDUP);
  293         BP_SET_LEVEL(bp, 0);
  294         BP_SET_DEDUP(bp, 1);
  295         BP_SET_BYTEORDER(bp, ZFS_HOST_BYTEORDER);
  296 }
  297 
  298 void
  299 ddt_key_fill(ddt_key_t *ddk, const blkptr_t *bp)
  300 {
  301         ddk->ddk_cksum = bp->blk_cksum;
  302         ddk->ddk_prop = 0;
  303 
  304         ASSERT(BP_IS_ENCRYPTED(bp) || !BP_USES_CRYPT(bp));
  305 
  306         DDK_SET_LSIZE(ddk, BP_GET_LSIZE(bp));
  307         DDK_SET_PSIZE(ddk, BP_GET_PSIZE(bp));
  308         DDK_SET_COMPRESS(ddk, BP_GET_COMPRESS(bp));
  309         DDK_SET_CRYPT(ddk, BP_USES_CRYPT(bp));
  310 }
  311 
  312 void
  313 ddt_phys_fill(ddt_phys_t *ddp, const blkptr_t *bp)
  314 {
  315         ASSERT(ddp->ddp_phys_birth == 0);
  316 
  317         for (int d = 0; d < SPA_DVAS_PER_BP; d++)
  318                 ddp->ddp_dva[d] = bp->blk_dva[d];
  319         ddp->ddp_phys_birth = BP_PHYSICAL_BIRTH(bp);
  320 }
  321 
  322 void
  323 ddt_phys_clear(ddt_phys_t *ddp)
  324 {
  325         memset(ddp, 0, sizeof (*ddp));
  326 }
  327 
  328 void
  329 ddt_phys_addref(ddt_phys_t *ddp)
  330 {
  331         ddp->ddp_refcnt++;
  332 }
  333 
  334 void
  335 ddt_phys_decref(ddt_phys_t *ddp)
  336 {
  337         if (ddp) {
  338                 ASSERT(ddp->ddp_refcnt > 0);
  339                 ddp->ddp_refcnt--;
  340         }
  341 }
  342 
  343 void
  344 ddt_phys_free(ddt_t *ddt, ddt_key_t *ddk, ddt_phys_t *ddp, uint64_t txg)
  345 {
  346         blkptr_t blk;
  347 
  348         ddt_bp_create(ddt->ddt_checksum, ddk, ddp, &blk);
  349 
  350         /*
  351          * We clear the dedup bit so that zio_free() will actually free the
  352          * space, rather than just decrementing the refcount in the DDT.
  353          */
  354         BP_SET_DEDUP(&blk, 0);
  355 
  356         ddt_phys_clear(ddp);
  357         zio_free(ddt->ddt_spa, txg, &blk);
  358 }
  359 
  360 ddt_phys_t *
  361 ddt_phys_select(const ddt_entry_t *dde, const blkptr_t *bp)
  362 {
  363         ddt_phys_t *ddp = (ddt_phys_t *)dde->dde_phys;
  364 
  365         for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
  366                 if (DVA_EQUAL(BP_IDENTITY(bp), &ddp->ddp_dva[0]) &&
  367                     BP_PHYSICAL_BIRTH(bp) == ddp->ddp_phys_birth)
  368                         return (ddp);
  369         }
  370         return (NULL);
  371 }
  372 
  373 uint64_t
  374 ddt_phys_total_refcnt(const ddt_entry_t *dde)
  375 {
  376         uint64_t refcnt = 0;
  377 
  378         for (int p = DDT_PHYS_SINGLE; p <= DDT_PHYS_TRIPLE; p++)
  379                 refcnt += dde->dde_phys[p].ddp_refcnt;
  380 
  381         return (refcnt);
  382 }
  383 
  384 static void
  385 ddt_stat_generate(ddt_t *ddt, ddt_entry_t *dde, ddt_stat_t *dds)
  386 {
  387         spa_t *spa = ddt->ddt_spa;
  388         ddt_phys_t *ddp = dde->dde_phys;
  389         ddt_key_t *ddk = &dde->dde_key;
  390         uint64_t lsize = DDK_GET_LSIZE(ddk);
  391         uint64_t psize = DDK_GET_PSIZE(ddk);
  392 
  393         memset(dds, 0, sizeof (*dds));
  394 
  395         for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
  396                 uint64_t dsize = 0;
  397                 uint64_t refcnt = ddp->ddp_refcnt;
  398 
  399                 if (ddp->ddp_phys_birth == 0)
  400                         continue;
  401 
  402                 for (int d = 0; d < DDE_GET_NDVAS(dde); d++)
  403                         dsize += dva_get_dsize_sync(spa, &ddp->ddp_dva[d]);
  404 
  405                 dds->dds_blocks += 1;
  406                 dds->dds_lsize += lsize;
  407                 dds->dds_psize += psize;
  408                 dds->dds_dsize += dsize;
  409 
  410                 dds->dds_ref_blocks += refcnt;
  411                 dds->dds_ref_lsize += lsize * refcnt;
  412                 dds->dds_ref_psize += psize * refcnt;
  413                 dds->dds_ref_dsize += dsize * refcnt;
  414         }
  415 }
  416 
  417 void
  418 ddt_stat_add(ddt_stat_t *dst, const ddt_stat_t *src, uint64_t neg)
  419 {
  420         const uint64_t *s = (const uint64_t *)src;
  421         uint64_t *d = (uint64_t *)dst;
  422         uint64_t *d_end = (uint64_t *)(dst + 1);
  423 
  424         ASSERT(neg == 0 || neg == -1ULL);       /* add or subtract */
  425 
  426         for (int i = 0; i < d_end - d; i++)
  427                 d[i] += (s[i] ^ neg) - neg;
  428 }
  429 
  430 static void
  431 ddt_stat_update(ddt_t *ddt, ddt_entry_t *dde, uint64_t neg)
  432 {
  433         ddt_stat_t dds;
  434         ddt_histogram_t *ddh;
  435         int bucket;
  436 
  437         ddt_stat_generate(ddt, dde, &dds);
  438 
  439         bucket = highbit64(dds.dds_ref_blocks) - 1;
  440         ASSERT(bucket >= 0);
  441 
  442         ddh = &ddt->ddt_histogram[dde->dde_type][dde->dde_class];
  443 
  444         ddt_stat_add(&ddh->ddh_stat[bucket], &dds, neg);
  445 }
  446 
  447 void
  448 ddt_histogram_add(ddt_histogram_t *dst, const ddt_histogram_t *src)
  449 {
  450         for (int h = 0; h < 64; h++)
  451                 ddt_stat_add(&dst->ddh_stat[h], &src->ddh_stat[h], 0);
  452 }
  453 
  454 void
  455 ddt_histogram_stat(ddt_stat_t *dds, const ddt_histogram_t *ddh)
  456 {
  457         memset(dds, 0, sizeof (*dds));
  458 
  459         for (int h = 0; h < 64; h++)
  460                 ddt_stat_add(dds, &ddh->ddh_stat[h], 0);
  461 }
  462 
  463 boolean_t
  464 ddt_histogram_empty(const ddt_histogram_t *ddh)
  465 {
  466         const uint64_t *s = (const uint64_t *)ddh;
  467         const uint64_t *s_end = (const uint64_t *)(ddh + 1);
  468 
  469         while (s < s_end)
  470                 if (*s++ != 0)
  471                         return (B_FALSE);
  472 
  473         return (B_TRUE);
  474 }
  475 
  476 void
  477 ddt_get_dedup_object_stats(spa_t *spa, ddt_object_t *ddo_total)
  478 {
  479         /* Sum the statistics we cached in ddt_object_sync(). */
  480         for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
  481                 ddt_t *ddt = spa->spa_ddt[c];
  482                 for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
  483                         for (enum ddt_class class = 0; class < DDT_CLASSES;
  484                             class++) {
  485                                 ddt_object_t *ddo =
  486                                     &ddt->ddt_object_stats[type][class];
  487                                 ddo_total->ddo_count += ddo->ddo_count;
  488                                 ddo_total->ddo_dspace += ddo->ddo_dspace;
  489                                 ddo_total->ddo_mspace += ddo->ddo_mspace;
  490                         }
  491                 }
  492         }
  493 
  494         /* ... and compute the averages. */
  495         if (ddo_total->ddo_count != 0) {
  496                 ddo_total->ddo_dspace /= ddo_total->ddo_count;
  497                 ddo_total->ddo_mspace /= ddo_total->ddo_count;
  498         }
  499 }
  500 
  501 void
  502 ddt_get_dedup_histogram(spa_t *spa, ddt_histogram_t *ddh)
  503 {
  504         for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
  505                 ddt_t *ddt = spa->spa_ddt[c];
  506                 for (enum ddt_type type = 0; type < DDT_TYPES && ddt; type++) {
  507                         for (enum ddt_class class = 0; class < DDT_CLASSES;
  508                             class++) {
  509                                 ddt_histogram_add(ddh,
  510                                     &ddt->ddt_histogram_cache[type][class]);
  511                         }
  512                 }
  513         }
  514 }
  515 
  516 void
  517 ddt_get_dedup_stats(spa_t *spa, ddt_stat_t *dds_total)
  518 {
  519         ddt_histogram_t *ddh_total;
  520 
  521         ddh_total = kmem_zalloc(sizeof (ddt_histogram_t), KM_SLEEP);
  522         ddt_get_dedup_histogram(spa, ddh_total);
  523         ddt_histogram_stat(dds_total, ddh_total);
  524         kmem_free(ddh_total, sizeof (ddt_histogram_t));
  525 }
  526 
  527 uint64_t
  528 ddt_get_dedup_dspace(spa_t *spa)
  529 {
  530         ddt_stat_t dds_total;
  531 
  532         if (spa->spa_dedup_dspace != ~0ULL)
  533                 return (spa->spa_dedup_dspace);
  534 
  535         memset(&dds_total, 0, sizeof (ddt_stat_t));
  536 
  537         /* Calculate and cache the stats */
  538         ddt_get_dedup_stats(spa, &dds_total);
  539         spa->spa_dedup_dspace = dds_total.dds_ref_dsize - dds_total.dds_dsize;
  540         return (spa->spa_dedup_dspace);
  541 }
  542 
  543 uint64_t
  544 ddt_get_pool_dedup_ratio(spa_t *spa)
  545 {
  546         ddt_stat_t dds_total = { 0 };
  547 
  548         ddt_get_dedup_stats(spa, &dds_total);
  549         if (dds_total.dds_dsize == 0)
  550                 return (100);
  551 
  552         return (dds_total.dds_ref_dsize * 100 / dds_total.dds_dsize);
  553 }
  554 
  555 size_t
  556 ddt_compress(void *src, uchar_t *dst, size_t s_len, size_t d_len)
  557 {
  558         uchar_t *version = dst++;
  559         int cpfunc = ZIO_COMPRESS_ZLE;
  560         zio_compress_info_t *ci = &zio_compress_table[cpfunc];
  561         size_t c_len;
  562 
  563         ASSERT(d_len >= s_len + 1);     /* no compression plus version byte */
  564 
  565         c_len = ci->ci_compress(src, dst, s_len, d_len - 1, ci->ci_level);
  566 
  567         if (c_len == s_len) {
  568                 cpfunc = ZIO_COMPRESS_OFF;
  569                 memcpy(dst, src, s_len);
  570         }
  571 
  572         *version = cpfunc;
  573         if (ZFS_HOST_BYTEORDER)
  574                 *version |= DDT_COMPRESS_BYTEORDER_MASK;
  575 
  576         return (c_len + 1);
  577 }
  578 
  579 void
  580 ddt_decompress(uchar_t *src, void *dst, size_t s_len, size_t d_len)
  581 {
  582         uchar_t version = *src++;
  583         int cpfunc = version & DDT_COMPRESS_FUNCTION_MASK;
  584         zio_compress_info_t *ci = &zio_compress_table[cpfunc];
  585 
  586         if (ci->ci_decompress != NULL)
  587                 (void) ci->ci_decompress(src, dst, s_len, d_len, ci->ci_level);
  588         else
  589                 memcpy(dst, src, d_len);
  590 
  591         if (((version & DDT_COMPRESS_BYTEORDER_MASK) != 0) !=
  592             (ZFS_HOST_BYTEORDER != 0))
  593                 byteswap_uint64_array(dst, d_len);
  594 }
  595 
  596 ddt_t *
  597 ddt_select(spa_t *spa, const blkptr_t *bp)
  598 {
  599         return (spa->spa_ddt[BP_GET_CHECKSUM(bp)]);
  600 }
  601 
  602 void
  603 ddt_enter(ddt_t *ddt)
  604 {
  605         mutex_enter(&ddt->ddt_lock);
  606 }
  607 
  608 void
  609 ddt_exit(ddt_t *ddt)
  610 {
  611         mutex_exit(&ddt->ddt_lock);
  612 }
  613 
  614 void
  615 ddt_init(void)
  616 {
  617         ddt_cache = kmem_cache_create("ddt_cache",
  618             sizeof (ddt_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
  619         ddt_entry_cache = kmem_cache_create("ddt_entry_cache",
  620             sizeof (ddt_entry_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
  621 }
  622 
  623 void
  624 ddt_fini(void)
  625 {
  626         kmem_cache_destroy(ddt_entry_cache);
  627         kmem_cache_destroy(ddt_cache);
  628 }
  629 
  630 static ddt_entry_t *
  631 ddt_alloc(const ddt_key_t *ddk)
  632 {
  633         ddt_entry_t *dde;
  634 
  635         dde = kmem_cache_alloc(ddt_entry_cache, KM_SLEEP);
  636         memset(dde, 0, sizeof (ddt_entry_t));
  637         cv_init(&dde->dde_cv, NULL, CV_DEFAULT, NULL);
  638 
  639         dde->dde_key = *ddk;
  640 
  641         return (dde);
  642 }
  643 
  644 static void
  645 ddt_free(ddt_entry_t *dde)
  646 {
  647         ASSERT(!dde->dde_loading);
  648 
  649         for (int p = 0; p < DDT_PHYS_TYPES; p++)
  650                 ASSERT(dde->dde_lead_zio[p] == NULL);
  651 
  652         if (dde->dde_repair_abd != NULL)
  653                 abd_free(dde->dde_repair_abd);
  654 
  655         cv_destroy(&dde->dde_cv);
  656         kmem_cache_free(ddt_entry_cache, dde);
  657 }
  658 
  659 void
  660 ddt_remove(ddt_t *ddt, ddt_entry_t *dde)
  661 {
  662         ASSERT(MUTEX_HELD(&ddt->ddt_lock));
  663 
  664         avl_remove(&ddt->ddt_tree, dde);
  665         ddt_free(dde);
  666 }
  667 
  668 ddt_entry_t *
  669 ddt_lookup(ddt_t *ddt, const blkptr_t *bp, boolean_t add)
  670 {
  671         ddt_entry_t *dde, dde_search;
  672         enum ddt_type type;
  673         enum ddt_class class;
  674         avl_index_t where;
  675         int error;
  676 
  677         ASSERT(MUTEX_HELD(&ddt->ddt_lock));
  678 
  679         ddt_key_fill(&dde_search.dde_key, bp);
  680 
  681         dde = avl_find(&ddt->ddt_tree, &dde_search, &where);
  682         if (dde == NULL) {
  683                 if (!add)
  684                         return (NULL);
  685                 dde = ddt_alloc(&dde_search.dde_key);
  686                 avl_insert(&ddt->ddt_tree, dde, where);
  687         }
  688 
  689         while (dde->dde_loading)
  690                 cv_wait(&dde->dde_cv, &ddt->ddt_lock);
  691 
  692         if (dde->dde_loaded)
  693                 return (dde);
  694 
  695         dde->dde_loading = B_TRUE;
  696 
  697         ddt_exit(ddt);
  698 
  699         error = ENOENT;
  700 
  701         for (type = 0; type < DDT_TYPES; type++) {
  702                 for (class = 0; class < DDT_CLASSES; class++) {
  703                         error = ddt_object_lookup(ddt, type, class, dde);
  704                         if (error != ENOENT) {
  705                                 ASSERT0(error);
  706                                 break;
  707                         }
  708                 }
  709                 if (error != ENOENT)
  710                         break;
  711         }
  712 
  713         ddt_enter(ddt);
  714 
  715         ASSERT(dde->dde_loaded == B_FALSE);
  716         ASSERT(dde->dde_loading == B_TRUE);
  717 
  718         dde->dde_type = type;   /* will be DDT_TYPES if no entry found */
  719         dde->dde_class = class; /* will be DDT_CLASSES if no entry found */
  720         dde->dde_loaded = B_TRUE;
  721         dde->dde_loading = B_FALSE;
  722 
  723         if (error == 0)
  724                 ddt_stat_update(ddt, dde, -1ULL);
  725 
  726         cv_broadcast(&dde->dde_cv);
  727 
  728         return (dde);
  729 }
  730 
  731 void
  732 ddt_prefetch(spa_t *spa, const blkptr_t *bp)
  733 {
  734         ddt_t *ddt;
  735         ddt_entry_t dde;
  736 
  737         if (!zfs_dedup_prefetch || bp == NULL || !BP_GET_DEDUP(bp))
  738                 return;
  739 
  740         /*
  741          * We only remove the DDT once all tables are empty and only
  742          * prefetch dedup blocks when there are entries in the DDT.
  743          * Thus no locking is required as the DDT can't disappear on us.
  744          */
  745         ddt = ddt_select(spa, bp);
  746         ddt_key_fill(&dde.dde_key, bp);
  747 
  748         for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
  749                 for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
  750                         ddt_object_prefetch(ddt, type, class, &dde);
  751                 }
  752         }
  753 }
  754 
  755 /*
  756  * Opaque struct used for ddt_key comparison
  757  */
  758 #define DDT_KEY_CMP_LEN (sizeof (ddt_key_t) / sizeof (uint16_t))
  759 
  760 typedef struct ddt_key_cmp {
  761         uint16_t        u16[DDT_KEY_CMP_LEN];
  762 } ddt_key_cmp_t;
  763 
  764 int
  765 ddt_entry_compare(const void *x1, const void *x2)
  766 {
  767         const ddt_entry_t *dde1 = x1;
  768         const ddt_entry_t *dde2 = x2;
  769         const ddt_key_cmp_t *k1 = (const ddt_key_cmp_t *)&dde1->dde_key;
  770         const ddt_key_cmp_t *k2 = (const ddt_key_cmp_t *)&dde2->dde_key;
  771         int32_t cmp = 0;
  772 
  773         for (int i = 0; i < DDT_KEY_CMP_LEN; i++) {
  774                 cmp = (int32_t)k1->u16[i] - (int32_t)k2->u16[i];
  775                 if (likely(cmp))
  776                         break;
  777         }
  778 
  779         return (TREE_ISIGN(cmp));
  780 }
  781 
  782 static ddt_t *
  783 ddt_table_alloc(spa_t *spa, enum zio_checksum c)
  784 {
  785         ddt_t *ddt;
  786 
  787         ddt = kmem_cache_alloc(ddt_cache, KM_SLEEP);
  788         memset(ddt, 0, sizeof (ddt_t));
  789 
  790         mutex_init(&ddt->ddt_lock, NULL, MUTEX_DEFAULT, NULL);
  791         avl_create(&ddt->ddt_tree, ddt_entry_compare,
  792             sizeof (ddt_entry_t), offsetof(ddt_entry_t, dde_node));
  793         avl_create(&ddt->ddt_repair_tree, ddt_entry_compare,
  794             sizeof (ddt_entry_t), offsetof(ddt_entry_t, dde_node));
  795         ddt->ddt_checksum = c;
  796         ddt->ddt_spa = spa;
  797         ddt->ddt_os = spa->spa_meta_objset;
  798 
  799         return (ddt);
  800 }
  801 
  802 static void
  803 ddt_table_free(ddt_t *ddt)
  804 {
  805         ASSERT(avl_numnodes(&ddt->ddt_tree) == 0);
  806         ASSERT(avl_numnodes(&ddt->ddt_repair_tree) == 0);
  807         avl_destroy(&ddt->ddt_tree);
  808         avl_destroy(&ddt->ddt_repair_tree);
  809         mutex_destroy(&ddt->ddt_lock);
  810         kmem_cache_free(ddt_cache, ddt);
  811 }
  812 
  813 void
  814 ddt_create(spa_t *spa)
  815 {
  816         spa->spa_dedup_checksum = ZIO_DEDUPCHECKSUM;
  817 
  818         for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++)
  819                 spa->spa_ddt[c] = ddt_table_alloc(spa, c);
  820 }
  821 
  822 int
  823 ddt_load(spa_t *spa)
  824 {
  825         int error;
  826 
  827         ddt_create(spa);
  828 
  829         error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
  830             DMU_POOL_DDT_STATS, sizeof (uint64_t), 1,
  831             &spa->spa_ddt_stat_object);
  832 
  833         if (error)
  834                 return (error == ENOENT ? 0 : error);
  835 
  836         for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
  837                 ddt_t *ddt = spa->spa_ddt[c];
  838                 for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
  839                         for (enum ddt_class class = 0; class < DDT_CLASSES;
  840                             class++) {
  841                                 error = ddt_object_load(ddt, type, class);
  842                                 if (error != 0 && error != ENOENT)
  843                                         return (error);
  844                         }
  845                 }
  846 
  847                 /*
  848                  * Seed the cached histograms.
  849                  */
  850                 memcpy(&ddt->ddt_histogram_cache, ddt->ddt_histogram,
  851                     sizeof (ddt->ddt_histogram));
  852                 spa->spa_dedup_dspace = ~0ULL;
  853         }
  854 
  855         return (0);
  856 }
  857 
  858 void
  859 ddt_unload(spa_t *spa)
  860 {
  861         for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
  862                 if (spa->spa_ddt[c]) {
  863                         ddt_table_free(spa->spa_ddt[c]);
  864                         spa->spa_ddt[c] = NULL;
  865                 }
  866         }
  867 }
  868 
  869 boolean_t
  870 ddt_class_contains(spa_t *spa, enum ddt_class max_class, const blkptr_t *bp)
  871 {
  872         ddt_t *ddt;
  873         ddt_entry_t *dde;
  874 
  875         if (!BP_GET_DEDUP(bp))
  876                 return (B_FALSE);
  877 
  878         if (max_class == DDT_CLASS_UNIQUE)
  879                 return (B_TRUE);
  880 
  881         ddt = spa->spa_ddt[BP_GET_CHECKSUM(bp)];
  882         dde = kmem_cache_alloc(ddt_entry_cache, KM_SLEEP);
  883 
  884         ddt_key_fill(&(dde->dde_key), bp);
  885 
  886         for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
  887                 for (enum ddt_class class = 0; class <= max_class; class++) {
  888                         if (ddt_object_lookup(ddt, type, class, dde) == 0) {
  889                                 kmem_cache_free(ddt_entry_cache, dde);
  890                                 return (B_TRUE);
  891                         }
  892                 }
  893         }
  894 
  895         kmem_cache_free(ddt_entry_cache, dde);
  896         return (B_FALSE);
  897 }
  898 
  899 ddt_entry_t *
  900 ddt_repair_start(ddt_t *ddt, const blkptr_t *bp)
  901 {
  902         ddt_key_t ddk;
  903         ddt_entry_t *dde;
  904 
  905         ddt_key_fill(&ddk, bp);
  906 
  907         dde = ddt_alloc(&ddk);
  908 
  909         for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
  910                 for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
  911                         /*
  912                          * We can only do repair if there are multiple copies
  913                          * of the block.  For anything in the UNIQUE class,
  914                          * there's definitely only one copy, so don't even try.
  915                          */
  916                         if (class != DDT_CLASS_UNIQUE &&
  917                             ddt_object_lookup(ddt, type, class, dde) == 0)
  918                                 return (dde);
  919                 }
  920         }
  921 
  922         memset(dde->dde_phys, 0, sizeof (dde->dde_phys));
  923 
  924         return (dde);
  925 }
  926 
  927 void
  928 ddt_repair_done(ddt_t *ddt, ddt_entry_t *dde)
  929 {
  930         avl_index_t where;
  931 
  932         ddt_enter(ddt);
  933 
  934         if (dde->dde_repair_abd != NULL && spa_writeable(ddt->ddt_spa) &&
  935             avl_find(&ddt->ddt_repair_tree, dde, &where) == NULL)
  936                 avl_insert(&ddt->ddt_repair_tree, dde, where);
  937         else
  938                 ddt_free(dde);
  939 
  940         ddt_exit(ddt);
  941 }
  942 
  943 static void
  944 ddt_repair_entry_done(zio_t *zio)
  945 {
  946         ddt_entry_t *rdde = zio->io_private;
  947 
  948         ddt_free(rdde);
  949 }
  950 
  951 static void
  952 ddt_repair_entry(ddt_t *ddt, ddt_entry_t *dde, ddt_entry_t *rdde, zio_t *rio)
  953 {
  954         ddt_phys_t *ddp = dde->dde_phys;
  955         ddt_phys_t *rddp = rdde->dde_phys;
  956         ddt_key_t *ddk = &dde->dde_key;
  957         ddt_key_t *rddk = &rdde->dde_key;
  958         zio_t *zio;
  959         blkptr_t blk;
  960 
  961         zio = zio_null(rio, rio->io_spa, NULL,
  962             ddt_repair_entry_done, rdde, rio->io_flags);
  963 
  964         for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++, rddp++) {
  965                 if (ddp->ddp_phys_birth == 0 ||
  966                     ddp->ddp_phys_birth != rddp->ddp_phys_birth ||
  967                     memcmp(ddp->ddp_dva, rddp->ddp_dva, sizeof (ddp->ddp_dva)))
  968                         continue;
  969                 ddt_bp_create(ddt->ddt_checksum, ddk, ddp, &blk);
  970                 zio_nowait(zio_rewrite(zio, zio->io_spa, 0, &blk,
  971                     rdde->dde_repair_abd, DDK_GET_PSIZE(rddk), NULL, NULL,
  972                     ZIO_PRIORITY_SYNC_WRITE, ZIO_DDT_CHILD_FLAGS(zio), NULL));
  973         }
  974 
  975         zio_nowait(zio);
  976 }
  977 
  978 static void
  979 ddt_repair_table(ddt_t *ddt, zio_t *rio)
  980 {
  981         spa_t *spa = ddt->ddt_spa;
  982         ddt_entry_t *dde, *rdde_next, *rdde;
  983         avl_tree_t *t = &ddt->ddt_repair_tree;
  984         blkptr_t blk;
  985 
  986         if (spa_sync_pass(spa) > 1)
  987                 return;
  988 
  989         ddt_enter(ddt);
  990         for (rdde = avl_first(t); rdde != NULL; rdde = rdde_next) {
  991                 rdde_next = AVL_NEXT(t, rdde);
  992                 avl_remove(&ddt->ddt_repair_tree, rdde);
  993                 ddt_exit(ddt);
  994                 ddt_bp_create(ddt->ddt_checksum, &rdde->dde_key, NULL, &blk);
  995                 dde = ddt_repair_start(ddt, &blk);
  996                 ddt_repair_entry(ddt, dde, rdde, rio);
  997                 ddt_repair_done(ddt, dde);
  998                 ddt_enter(ddt);
  999         }
 1000         ddt_exit(ddt);
 1001 }
 1002 
 1003 static void
 1004 ddt_sync_entry(ddt_t *ddt, ddt_entry_t *dde, dmu_tx_t *tx, uint64_t txg)
 1005 {
 1006         dsl_pool_t *dp = ddt->ddt_spa->spa_dsl_pool;
 1007         ddt_phys_t *ddp = dde->dde_phys;
 1008         ddt_key_t *ddk = &dde->dde_key;
 1009         enum ddt_type otype = dde->dde_type;
 1010         enum ddt_type ntype = DDT_TYPE_CURRENT;
 1011         enum ddt_class oclass = dde->dde_class;
 1012         enum ddt_class nclass;
 1013         uint64_t total_refcnt = 0;
 1014 
 1015         ASSERT(dde->dde_loaded);
 1016         ASSERT(!dde->dde_loading);
 1017 
 1018         for (int p = 0; p < DDT_PHYS_TYPES; p++, ddp++) {
 1019                 ASSERT(dde->dde_lead_zio[p] == NULL);
 1020                 if (ddp->ddp_phys_birth == 0) {
 1021                         ASSERT(ddp->ddp_refcnt == 0);
 1022                         continue;
 1023                 }
 1024                 if (p == DDT_PHYS_DITTO) {
 1025                         /*
 1026                          * Note, we no longer create DDT-DITTO blocks, but we
 1027                          * don't want to leak any written by older software.
 1028                          */
 1029                         ddt_phys_free(ddt, ddk, ddp, txg);
 1030                         continue;
 1031                 }
 1032                 if (ddp->ddp_refcnt == 0)
 1033                         ddt_phys_free(ddt, ddk, ddp, txg);
 1034                 total_refcnt += ddp->ddp_refcnt;
 1035         }
 1036 
 1037         /* We do not create new DDT-DITTO blocks. */
 1038         ASSERT0(dde->dde_phys[DDT_PHYS_DITTO].ddp_phys_birth);
 1039         if (total_refcnt > 1)
 1040                 nclass = DDT_CLASS_DUPLICATE;
 1041         else
 1042                 nclass = DDT_CLASS_UNIQUE;
 1043 
 1044         if (otype != DDT_TYPES &&
 1045             (otype != ntype || oclass != nclass || total_refcnt == 0)) {
 1046                 VERIFY(ddt_object_remove(ddt, otype, oclass, dde, tx) == 0);
 1047                 ASSERT(ddt_object_lookup(ddt, otype, oclass, dde) == ENOENT);
 1048         }
 1049 
 1050         if (total_refcnt != 0) {
 1051                 dde->dde_type = ntype;
 1052                 dde->dde_class = nclass;
 1053                 ddt_stat_update(ddt, dde, 0);
 1054                 if (!ddt_object_exists(ddt, ntype, nclass))
 1055                         ddt_object_create(ddt, ntype, nclass, tx);
 1056                 VERIFY(ddt_object_update(ddt, ntype, nclass, dde, tx) == 0);
 1057 
 1058                 /*
 1059                  * If the class changes, the order that we scan this bp
 1060                  * changes.  If it decreases, we could miss it, so
 1061                  * scan it right now.  (This covers both class changing
 1062                  * while we are doing ddt_walk(), and when we are
 1063                  * traversing.)
 1064                  */
 1065                 if (nclass < oclass) {
 1066                         dsl_scan_ddt_entry(dp->dp_scan,
 1067                             ddt->ddt_checksum, dde, tx);
 1068                 }
 1069         }
 1070 }
 1071 
 1072 static void
 1073 ddt_sync_table(ddt_t *ddt, dmu_tx_t *tx, uint64_t txg)
 1074 {
 1075         spa_t *spa = ddt->ddt_spa;
 1076         ddt_entry_t *dde;
 1077         void *cookie = NULL;
 1078 
 1079         if (avl_numnodes(&ddt->ddt_tree) == 0)
 1080                 return;
 1081 
 1082         ASSERT(spa->spa_uberblock.ub_version >= SPA_VERSION_DEDUP);
 1083 
 1084         if (spa->spa_ddt_stat_object == 0) {
 1085                 spa->spa_ddt_stat_object = zap_create_link(ddt->ddt_os,
 1086                     DMU_OT_DDT_STATS, DMU_POOL_DIRECTORY_OBJECT,
 1087                     DMU_POOL_DDT_STATS, tx);
 1088         }
 1089 
 1090         while ((dde = avl_destroy_nodes(&ddt->ddt_tree, &cookie)) != NULL) {
 1091                 ddt_sync_entry(ddt, dde, tx, txg);
 1092                 ddt_free(dde);
 1093         }
 1094 
 1095         for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
 1096                 uint64_t add, count = 0;
 1097                 for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
 1098                         if (ddt_object_exists(ddt, type, class)) {
 1099                                 ddt_object_sync(ddt, type, class, tx);
 1100                                 VERIFY(ddt_object_count(ddt, type, class,
 1101                                     &add) == 0);
 1102                                 count += add;
 1103                         }
 1104                 }
 1105                 for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
 1106                         if (count == 0 && ddt_object_exists(ddt, type, class))
 1107                                 ddt_object_destroy(ddt, type, class, tx);
 1108                 }
 1109         }
 1110 
 1111         memcpy(&ddt->ddt_histogram_cache, ddt->ddt_histogram,
 1112             sizeof (ddt->ddt_histogram));
 1113         spa->spa_dedup_dspace = ~0ULL;
 1114 }
 1115 
 1116 void
 1117 ddt_sync(spa_t *spa, uint64_t txg)
 1118 {
 1119         dsl_scan_t *scn = spa->spa_dsl_pool->dp_scan;
 1120         dmu_tx_t *tx;
 1121         zio_t *rio;
 1122 
 1123         ASSERT(spa_syncing_txg(spa) == txg);
 1124 
 1125         tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
 1126 
 1127         rio = zio_root(spa, NULL, NULL,
 1128             ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SELF_HEAL);
 1129 
 1130         /*
 1131          * This function may cause an immediate scan of ddt blocks (see
 1132          * the comment above dsl_scan_ddt() for details). We set the
 1133          * scan's root zio here so that we can wait for any scan IOs in
 1134          * addition to the regular ddt IOs.
 1135          */
 1136         ASSERT3P(scn->scn_zio_root, ==, NULL);
 1137         scn->scn_zio_root = rio;
 1138 
 1139         for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
 1140                 ddt_t *ddt = spa->spa_ddt[c];
 1141                 if (ddt == NULL)
 1142                         continue;
 1143                 ddt_sync_table(ddt, tx, txg);
 1144                 ddt_repair_table(ddt, rio);
 1145         }
 1146 
 1147         (void) zio_wait(rio);
 1148         scn->scn_zio_root = NULL;
 1149 
 1150         dmu_tx_commit(tx);
 1151 }
 1152 
 1153 int
 1154 ddt_walk(spa_t *spa, ddt_bookmark_t *ddb, ddt_entry_t *dde)
 1155 {
 1156         do {
 1157                 do {
 1158                         do {
 1159                                 ddt_t *ddt = spa->spa_ddt[ddb->ddb_checksum];
 1160                                 int error = ENOENT;
 1161                                 if (ddt_object_exists(ddt, ddb->ddb_type,
 1162                                     ddb->ddb_class)) {
 1163                                         error = ddt_object_walk(ddt,
 1164                                             ddb->ddb_type, ddb->ddb_class,
 1165                                             &ddb->ddb_cursor, dde);
 1166                                 }
 1167                                 dde->dde_type = ddb->ddb_type;
 1168                                 dde->dde_class = ddb->ddb_class;
 1169                                 if (error == 0)
 1170                                         return (0);
 1171                                 if (error != ENOENT)
 1172                                         return (error);
 1173                                 ddb->ddb_cursor = 0;
 1174                         } while (++ddb->ddb_checksum < ZIO_CHECKSUM_FUNCTIONS);
 1175                         ddb->ddb_checksum = 0;
 1176                 } while (++ddb->ddb_type < DDT_TYPES);
 1177                 ddb->ddb_type = 0;
 1178         } while (++ddb->ddb_class < DDT_CLASSES);
 1179 
 1180         return (SET_ERROR(ENOENT));
 1181 }
 1182 
 1183 ZFS_MODULE_PARAM(zfs_dedup, zfs_dedup_, prefetch, INT, ZMOD_RW,
 1184         "Enable prefetching dedup-ed blks");
Cache object: c11a71d7ad6f0202cad49176b77f463e
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FreeBSD/Linux Kernel Cross Reference sys/contrib/openzfs/module/zfs/ddt.c

FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/module/zfs/ddt.c
