1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  23  */
  24 /*
  25  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  26  * Copyright (c) 2013, Joyent, Inc. All rights reserved.
  27  * Copyright 2016 Nexenta Systems, Inc. All rights reserved.
  28  * Copyright (c) 2011, 2017 by Delphix. All rights reserved.
  29  * Copyright (c) 2018 DilOS
  30  */
  31 
  32 #include <sys/dmu.h>
  33 #include <sys/dmu_impl.h>
  34 #include <sys/dmu_tx.h>
  35 #include <sys/dbuf.h>
  36 #include <sys/dnode.h>
  37 #include <sys/zfs_context.h>
  38 #include <sys/dmu_objset.h>
  39 #include <sys/dmu_traverse.h>
  40 #include <sys/dsl_dataset.h>
  41 #include <sys/dsl_dir.h>
  42 #include <sys/dsl_pool.h>
  43 #include <sys/dsl_synctask.h>
  44 #include <sys/dsl_prop.h>
  45 #include <sys/dmu_zfetch.h>
  46 #include <sys/zfs_ioctl.h>
  47 #include <sys/zap.h>
  48 #include <sys/zio_checksum.h>
  49 #include <sys/zio_compress.h>
  50 #include <sys/sa.h>
  51 #include <sys/zfeature.h>
  52 #include <sys/abd.h>
  53 #ifdef _KERNEL
  54 #include <sys/vmsystm.h>
  55 #include <sys/zfs_znode.h>
  56 #endif
  57 
  58 static xuio_stats_t xuio_stats = {
  59         { "onloan_read_buf",    KSTAT_DATA_UINT64 },
  60         { "onloan_write_buf",   KSTAT_DATA_UINT64 },
  61         { "read_buf_copied",    KSTAT_DATA_UINT64 },
  62         { "read_buf_nocopy",    KSTAT_DATA_UINT64 },
  63         { "write_buf_copied",   KSTAT_DATA_UINT64 },
  64         { "write_buf_nocopy",   KSTAT_DATA_UINT64 }
  65 };
  66 
  67 #define XUIOSTAT_INCR(stat, val)        \
  68         atomic_add_64(&xuio_stats.stat.value.ui64, (val))
  69 #define XUIOSTAT_BUMP(stat)     XUIOSTAT_INCR(stat, 1)
  70 
  71 /*
  72  * Enable/disable nopwrite feature.
  73  */
  74 int zfs_nopwrite_enabled = 1;
  75 
  76 /*
  77  * Tunable to control percentage of dirtied blocks from frees in one TXG.
  78  * After this threshold is crossed, additional dirty blocks from frees
  79  * wait until the next TXG.
  80  * A value of zero will disable this throttle.
  81  */
  82 uint32_t zfs_per_txg_dirty_frees_percent = 30;
  83 
  84 /*
  85  * This can be used for testing, to ensure that certain actions happen
  86  * while in the middle of a remap (which might otherwise complete too
  87  * quickly).
  88  */
  89 int zfs_object_remap_one_indirect_delay_ticks = 0;
  90 
  91 /*
  92  * Limit the amount we can prefetch with one call to this amount.  This
  93  * helps to limit the amount of memory that can be used by prefetching.
  94  * Larger objects should be prefetched a bit at a time.
  95  */
  96 uint64_t dmu_prefetch_max = 8 * SPA_MAXBLOCKSIZE;
  97 
  98 const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES] = {
  99         { DMU_BSWAP_UINT8,  TRUE,  FALSE, FALSE, "unallocated"          },
 100         { DMU_BSWAP_ZAP,    TRUE,  TRUE,  FALSE, "object directory"     },
 101         { DMU_BSWAP_UINT64, TRUE,  TRUE,  FALSE, "object array"         },
 102         { DMU_BSWAP_UINT8,  TRUE,  FALSE, FALSE, "packed nvlist"        },
 103         { DMU_BSWAP_UINT64, TRUE,  FALSE, FALSE, "packed nvlist size"   },
 104         { DMU_BSWAP_UINT64, TRUE,  FALSE, FALSE, "bpobj"        },
 105         { DMU_BSWAP_UINT64, TRUE,  FALSE, FALSE, "bpobj header"         },
 106         { DMU_BSWAP_UINT64, TRUE,  FALSE, FALSE, "SPA space map header" },
 107         { DMU_BSWAP_UINT64, TRUE,  FALSE, FALSE, "SPA space map"        },
 108         { DMU_BSWAP_UINT64, TRUE,  FALSE, TRUE,  "ZIL intent log"       },
 109         { DMU_BSWAP_DNODE,  TRUE,  FALSE, TRUE,  "DMU dnode"    },
 110         { DMU_BSWAP_OBJSET, TRUE,  TRUE,  FALSE, "DMU objset"   },
 111         { DMU_BSWAP_UINT64, TRUE,  TRUE,  FALSE, "DSL directory"        },
 112         { DMU_BSWAP_ZAP,    TRUE,  TRUE,  FALSE, "DSL directory child map" },
 113         { DMU_BSWAP_ZAP,    TRUE,  TRUE,  FALSE, "DSL dataset snap map" },
 114         { DMU_BSWAP_ZAP,    TRUE,  TRUE,  FALSE, "DSL props"    },
 115         { DMU_BSWAP_UINT64, TRUE,  TRUE,  FALSE, "DSL dataset"  },
 116         { DMU_BSWAP_ZNODE,  TRUE,  FALSE, FALSE, "ZFS znode"    },
 117         { DMU_BSWAP_OLDACL, TRUE,  FALSE, TRUE,  "ZFS V0 ACL"   },
 118         { DMU_BSWAP_UINT8,  FALSE, FALSE, TRUE,  "ZFS plain file"       },
 119         { DMU_BSWAP_ZAP,    TRUE,  FALSE, TRUE,  "ZFS directory"        },
 120         { DMU_BSWAP_ZAP,    TRUE,  FALSE, FALSE, "ZFS master node"      },
 121         { DMU_BSWAP_ZAP,    TRUE,  FALSE, TRUE,  "ZFS delete queue"     },
 122         { DMU_BSWAP_UINT8,  FALSE, FALSE, TRUE,  "zvol object"  },
 123         { DMU_BSWAP_ZAP,    TRUE,  FALSE, FALSE, "zvol prop"    },
 124         { DMU_BSWAP_UINT8,  FALSE, FALSE, TRUE,  "other uint8[]"        },
 125         { DMU_BSWAP_UINT64, FALSE, FALSE, TRUE,  "other uint64[]"       },
 126         { DMU_BSWAP_ZAP,    TRUE,  FALSE, FALSE, "other ZAP"    },
 127         { DMU_BSWAP_ZAP,    TRUE,  FALSE, FALSE, "persistent error log" },
 128         { DMU_BSWAP_UINT8,  TRUE,  FALSE, FALSE, "SPA history"  },
 129         { DMU_BSWAP_UINT64, TRUE,  FALSE, FALSE, "SPA history offsets"  },
 130         { DMU_BSWAP_ZAP,    TRUE,  TRUE,  FALSE, "Pool properties"      },
 131         { DMU_BSWAP_ZAP,    TRUE,  TRUE,  FALSE, "DSL permissions"      },
 132         { DMU_BSWAP_ACL,    TRUE,  FALSE, TRUE,  "ZFS ACL"      },
 133         { DMU_BSWAP_UINT8,  TRUE,  FALSE, TRUE,  "ZFS SYSACL"   },
 134         { DMU_BSWAP_UINT8,  TRUE,  FALSE, TRUE,  "FUID table"   },
 135         { DMU_BSWAP_UINT64, TRUE,  FALSE, FALSE, "FUID table size"      },
 136         { DMU_BSWAP_ZAP,    TRUE,  TRUE,  FALSE, "DSL dataset next clones" },
 137         { DMU_BSWAP_ZAP,    TRUE,  FALSE, FALSE, "scan work queue"      },
 138         { DMU_BSWAP_ZAP,    TRUE,  FALSE, TRUE,  "ZFS user/group used"  },
 139         { DMU_BSWAP_ZAP,    TRUE,  FALSE, TRUE,  "ZFS user/group quota" },
 140         { DMU_BSWAP_ZAP,    TRUE,  TRUE,  FALSE, "snapshot refcount tags" },
 141         { DMU_BSWAP_ZAP,    TRUE,  FALSE, FALSE, "DDT ZAP algorithm"    },
 142         { DMU_BSWAP_ZAP,    TRUE,  FALSE, FALSE, "DDT statistics"       },
 143         { DMU_BSWAP_UINT8,  TRUE,  FALSE, TRUE,  "System attributes"    },
 144         { DMU_BSWAP_ZAP,    TRUE,  FALSE, TRUE,  "SA master node"       },
 145         { DMU_BSWAP_ZAP,    TRUE,  FALSE, TRUE,  "SA attr registration" },
 146         { DMU_BSWAP_ZAP,    TRUE,  FALSE, TRUE,  "SA attr layouts"      },
 147         { DMU_BSWAP_ZAP,    TRUE,  FALSE, FALSE, "scan translations"    },
 148         { DMU_BSWAP_UINT8,  FALSE, FALSE, TRUE,  "deduplicated block"   },
 149         { DMU_BSWAP_ZAP,    TRUE,  TRUE,  FALSE, "DSL deadlist map" },
 150         { DMU_BSWAP_UINT64, TRUE,  TRUE,  FALSE, "DSL deadlist map hdr" },
 151         { DMU_BSWAP_ZAP,    TRUE,  TRUE,  FALSE, "DSL dir clones"       },
 152         { DMU_BSWAP_UINT64, TRUE,  FALSE, FALSE, "bpobj subobj"         }
 153 };
 154 
 155 const dmu_object_byteswap_info_t dmu_ot_byteswap[DMU_BSWAP_NUMFUNCS] = {
 156         {       byteswap_uint8_array,   "uint8"         },
 157         {       byteswap_uint16_array,  "uint16"        },
 158         {       byteswap_uint32_array,  "uint32"        },
 159         {       byteswap_uint64_array,  "uint64"        },
 160         {       zap_byteswap,           "zap"           },
 161         {       dnode_buf_byteswap,     "dnode"         },
 162         {       dmu_objset_byteswap,    "objset"        },
 163         {       zfs_znode_byteswap,     "znode"         },
 164         {       zfs_oldacl_byteswap,    "oldacl"        },
 165         {       zfs_acl_byteswap,       "acl"           }
 166 };
 167 
 168 int
 169 dmu_buf_hold_noread_by_dnode(dnode_t *dn, uint64_t offset,
 170     void *tag, dmu_buf_t **dbp)
 171 {
 172         uint64_t blkid;
 173         dmu_buf_impl_t *db;
 174 
 175         blkid = dbuf_whichblock(dn, 0, offset);
 176         rw_enter(&dn->dn_struct_rwlock, RW_READER);
 177         db = dbuf_hold(dn, blkid, tag);
 178         rw_exit(&dn->dn_struct_rwlock);
 179 
 180         if (db == NULL) {
 181                 *dbp = NULL;
 182                 return (SET_ERROR(EIO));
 183         }
 184 
 185         *dbp = &db->db;
 186         return (0);
 187 }
 188 int
 189 dmu_buf_hold_noread(objset_t *os, uint64_t object, uint64_t offset,
 190     void *tag, dmu_buf_t **dbp)
 191 {
 192         dnode_t *dn;
 193         uint64_t blkid;
 194         dmu_buf_impl_t *db;
 195         int err;
 196 
 197         err = dnode_hold(os, object, FTAG, &dn);
 198         if (err)
 199                 return (err);
 200         blkid = dbuf_whichblock(dn, 0, offset);
 201         rw_enter(&dn->dn_struct_rwlock, RW_READER);
 202         db = dbuf_hold(dn, blkid, tag);
 203         rw_exit(&dn->dn_struct_rwlock);
 204         dnode_rele(dn, FTAG);
 205 
 206         if (db == NULL) {
 207                 *dbp = NULL;
 208                 return (SET_ERROR(EIO));
 209         }
 210 
 211         *dbp = &db->db;
 212         return (err);
 213 }
 214 
 215 int
 216 dmu_buf_hold_by_dnode(dnode_t *dn, uint64_t offset,
 217     void *tag, dmu_buf_t **dbp, int flags)
 218 {
 219         int err;
 220         int db_flags = DB_RF_CANFAIL;
 221 
 222         if (flags & DMU_READ_NO_PREFETCH)
 223                 db_flags |= DB_RF_NOPREFETCH;
 224         if (flags & DMU_READ_NO_DECRYPT)
 225                 db_flags |= DB_RF_NO_DECRYPT;
 226 
 227         err = dmu_buf_hold_noread_by_dnode(dn, offset, tag, dbp);
 228         if (err == 0) {
 229                 dmu_buf_impl_t *db = (dmu_buf_impl_t *)(*dbp);
 230                 err = dbuf_read(db, NULL, db_flags);
 231                 if (err != 0) {
 232                         dbuf_rele(db, tag);
 233                         *dbp = NULL;
 234                 }
 235         }
 236 
 237         return (err);
 238 }
 239 
 240 int
 241 dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
 242     void *tag, dmu_buf_t **dbp, int flags)
 243 {
 244         int err;
 245         int db_flags = DB_RF_CANFAIL;
 246 
 247         if (flags & DMU_READ_NO_PREFETCH)
 248                 db_flags |= DB_RF_NOPREFETCH;
 249         if (flags & DMU_READ_NO_DECRYPT)
 250                 db_flags |= DB_RF_NO_DECRYPT;
 251 
 252         err = dmu_buf_hold_noread(os, object, offset, tag, dbp);
 253         if (err == 0) {
 254                 dmu_buf_impl_t *db = (dmu_buf_impl_t *)(*dbp);
 255                 err = dbuf_read(db, NULL, db_flags);
 256                 if (err != 0) {
 257                         dbuf_rele(db, tag);
 258                         *dbp = NULL;
 259                 }
 260         }
 261 
 262         return (err);
 263 }
 264 
 265 int
 266 dmu_bonus_max(void)
 267 {
 268         return (DN_OLD_MAX_BONUSLEN);
 269 }
 270 
 271 int
 272 dmu_set_bonus(dmu_buf_t *db_fake, int newsize, dmu_tx_t *tx)
 273 {
 274         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
 275         dnode_t *dn;
 276         int error;
 277 
 278         DB_DNODE_ENTER(db);
 279         dn = DB_DNODE(db);
 280 
 281         if (dn->dn_bonus != db) {
 282                 error = SET_ERROR(EINVAL);
 283         } else if (newsize < 0 || newsize > db_fake->db_size) {
 284                 error = SET_ERROR(EINVAL);
 285         } else {
 286                 dnode_setbonuslen(dn, newsize, tx);
 287                 error = 0;
 288         }
 289 
 290         DB_DNODE_EXIT(db);
 291         return (error);
 292 }
 293 
 294 int
 295 dmu_set_bonustype(dmu_buf_t *db_fake, dmu_object_type_t type, dmu_tx_t *tx)
 296 {
 297         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
 298         dnode_t *dn;
 299         int error;
 300 
 301         DB_DNODE_ENTER(db);
 302         dn = DB_DNODE(db);
 303 
 304         if (!DMU_OT_IS_VALID(type)) {
 305                 error = SET_ERROR(EINVAL);
 306         } else if (dn->dn_bonus != db) {
 307                 error = SET_ERROR(EINVAL);
 308         } else {
 309                 dnode_setbonus_type(dn, type, tx);
 310                 error = 0;
 311         }
 312 
 313         DB_DNODE_EXIT(db);
 314         return (error);
 315 }
 316 
 317 dmu_object_type_t
 318 dmu_get_bonustype(dmu_buf_t *db_fake)
 319 {
 320         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
 321         dnode_t *dn;
 322         dmu_object_type_t type;
 323 
 324         DB_DNODE_ENTER(db);
 325         dn = DB_DNODE(db);
 326         type = dn->dn_bonustype;
 327         DB_DNODE_EXIT(db);
 328 
 329         return (type);
 330 }
 331 
 332 int
 333 dmu_rm_spill(objset_t *os, uint64_t object, dmu_tx_t *tx)
 334 {
 335         dnode_t *dn;
 336         int error;
 337 
 338         error = dnode_hold(os, object, FTAG, &dn);
 339         dbuf_rm_spill(dn, tx);
 340         rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
 341         dnode_rm_spill(dn, tx);
 342         rw_exit(&dn->dn_struct_rwlock);
 343         dnode_rele(dn, FTAG);
 344         return (error);
 345 }
 346 
 347 /*
 348  * Lookup and hold the bonus buffer for the provided dnode.  If the dnode
 349  * has not yet been allocated a new bonus dbuf a will be allocated.
 350  * Returns ENOENT, EIO, or 0.
 351  */
 352 int dmu_bonus_hold_by_dnode(dnode_t *dn, void *tag, dmu_buf_t **dbp,
 353     uint32_t flags)
 354 {
 355         dmu_buf_impl_t *db;
 356         int error;
 357         uint32_t db_flags = DB_RF_MUST_SUCCEED;
 358 
 359         if (flags & DMU_READ_NO_PREFETCH)
 360                 db_flags |= DB_RF_NOPREFETCH;
 361         if (flags & DMU_READ_NO_DECRYPT)
 362         db_flags |= DB_RF_NO_DECRYPT;
 363 
 364         rw_enter(&dn->dn_struct_rwlock, RW_READER);
 365         if (dn->dn_bonus == NULL) {
 366                 rw_exit(&dn->dn_struct_rwlock);
 367                 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
 368                 if (dn->dn_bonus == NULL)
 369                         dbuf_create_bonus(dn);
 370         }
 371         db = dn->dn_bonus;
 372 
 373         /* as long as the bonus buf is held, the dnode will be held */
 374         if (zfs_refcount_add(&db->db_holds, tag) == 1) {
 375                 VERIFY(dnode_add_ref(dn, db));
 376                 atomic_inc_32(&dn->dn_dbufs_count);
 377         }
 378 
 379         /*
 380          * Wait to drop dn_struct_rwlock until after adding the bonus dbuf's
 381          * hold and incrementing the dbuf count to ensure that dnode_move() sees
 382          * a dnode hold for every dbuf.
 383          */
 384         rw_exit(&dn->dn_struct_rwlock);
 385 
 386         error = dbuf_read(db, NULL, db_flags);
 387         if (error) {
 388                 dnode_evict_bonus(dn);
 389                 dbuf_rele(db, tag);
 390                 *dbp = NULL;
 391                 return (error);
 392         }
 393 
 394         *dbp = &db->db;
 395         return (0);
 396 }
 397 
 398 /*
 399  * returns ENOENT, EIO, or 0.
 400  */
 401 int
 402 dmu_bonus_hold_impl(objset_t *os, uint64_t object, void *tag, uint32_t flags,
 403     dmu_buf_t **dbp)
 404 {
 405         dnode_t *dn;
 406         dmu_buf_impl_t *db;
 407         int error;
 408         uint32_t db_flags = DB_RF_MUST_SUCCEED;
 409 
 410         if (flags & DMU_READ_NO_PREFETCH)
 411                 db_flags |= DB_RF_NOPREFETCH;
 412         if (flags & DMU_READ_NO_DECRYPT)
 413                 db_flags |= DB_RF_NO_DECRYPT;
 414 
 415         error = dnode_hold(os, object, FTAG, &dn);
 416         if (error)
 417                 return (error);
 418 
 419         rw_enter(&dn->dn_struct_rwlock, RW_READER);
 420         if (dn->dn_bonus == NULL) {
 421                 rw_exit(&dn->dn_struct_rwlock);
 422                 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
 423                 if (dn->dn_bonus == NULL)
 424                         dbuf_create_bonus(dn);
 425         }
 426         db = dn->dn_bonus;
 427 
 428         /* as long as the bonus buf is held, the dnode will be held */
 429         if (zfs_refcount_add(&db->db_holds, tag) == 1) {
 430                 VERIFY(dnode_add_ref(dn, db));
 431                 atomic_inc_32(&dn->dn_dbufs_count);
 432         }
 433 
 434         /*
 435          * Wait to drop dn_struct_rwlock until after adding the bonus dbuf's
 436          * hold and incrementing the dbuf count to ensure that dnode_move() sees
 437          * a dnode hold for every dbuf.
 438          */
 439         rw_exit(&dn->dn_struct_rwlock);
 440 
 441         dnode_rele(dn, FTAG);
 442 
 443         error = dbuf_read(db, NULL, db_flags);
 444         if (error) {
 445                 dnode_evict_bonus(dn);
 446                 dbuf_rele(db, tag);
 447                 *dbp = NULL;
 448                 return (error);
 449         }
 450 
 451         *dbp = &db->db;
 452         return (0);
 453 }
 454 
 455 int
 456 dmu_bonus_hold(objset_t *os, uint64_t obj, void *tag, dmu_buf_t **dbp)
 457 {
 458         return (dmu_bonus_hold_impl(os, obj, tag, DMU_READ_NO_PREFETCH, dbp));
 459 }
 460 
 461 /*
 462  * returns ENOENT, EIO, or 0.
 463  *
 464  * This interface will allocate a blank spill dbuf when a spill blk
 465  * doesn't already exist on the dnode.
 466  *
 467  * if you only want to find an already existing spill db, then
 468  * dmu_spill_hold_existing() should be used.
 469  */
 470 int
 471 dmu_spill_hold_by_dnode(dnode_t *dn, uint32_t flags, void *tag, dmu_buf_t **dbp)
 472 {
 473         dmu_buf_impl_t *db = NULL;
 474         int err;
 475 
 476         if ((flags & DB_RF_HAVESTRUCT) == 0)
 477                 rw_enter(&dn->dn_struct_rwlock, RW_READER);
 478 
 479         db = dbuf_hold(dn, DMU_SPILL_BLKID, tag);
 480 
 481         if ((flags & DB_RF_HAVESTRUCT) == 0)
 482                 rw_exit(&dn->dn_struct_rwlock);
 483 
 484         ASSERT(db != NULL);
 485         err = dbuf_read(db, NULL, flags);
 486         if (err == 0)
 487                 *dbp = &db->db;
 488         else
 489                 dbuf_rele(db, tag);
 490         return (err);
 491 }
 492 
 493 int
 494 dmu_spill_hold_existing(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp)
 495 {
 496         dmu_buf_impl_t *db = (dmu_buf_impl_t *)bonus;
 497         dnode_t *dn;
 498         int err;
 499 
 500         DB_DNODE_ENTER(db);
 501         dn = DB_DNODE(db);
 502 
 503         if (spa_version(dn->dn_objset->os_spa) < SPA_VERSION_SA) {
 504                 err = SET_ERROR(EINVAL);
 505         } else {
 506                 rw_enter(&dn->dn_struct_rwlock, RW_READER);
 507 
 508                 if (!dn->dn_have_spill) {
 509                         err = SET_ERROR(ENOENT);
 510                 } else {
 511                         err = dmu_spill_hold_by_dnode(dn,
 512                             DB_RF_HAVESTRUCT | DB_RF_CANFAIL, tag, dbp);
 513                 }
 514 
 515                 rw_exit(&dn->dn_struct_rwlock);
 516         }
 517 
 518         DB_DNODE_EXIT(db);
 519         return (err);
 520 }
 521 
 522 int
 523 dmu_spill_hold_by_bonus(dmu_buf_t *bonus, uint32_t flags, void *tag,
 524     dmu_buf_t **dbp)
 525 {
 526         dmu_buf_impl_t *db = (dmu_buf_impl_t *)bonus;
 527         dnode_t *dn;
 528         int err;
 529         uint32_t db_flags = DB_RF_CANFAIL;
 530 
 531         if (flags & DMU_READ_NO_DECRYPT)
 532                 db_flags |= DB_RF_NO_DECRYPT;
 533 
 534         DB_DNODE_ENTER(db);
 535         dn = DB_DNODE(db);
 536         err = dmu_spill_hold_by_dnode(dn, db_flags, tag, dbp);
 537         DB_DNODE_EXIT(db);
 538 
 539         return (err);
 540 }
 541 
 542 /*
 543  * Note: longer-term, we should modify all of the dmu_buf_*() interfaces
 544  * to take a held dnode rather than <os, object> -- the lookup is wasteful,
 545  * and can induce severe lock contention when writing to several files
 546  * whose dnodes are in the same block.
 547  */
 548 int
 549 dmu_buf_hold_array_by_dnode(dnode_t *dn, uint64_t offset, uint64_t length,
 550     boolean_t read, void *tag, int *numbufsp, dmu_buf_t ***dbpp, uint32_t flags)
 551 {
 552         dmu_buf_t **dbp;
 553         uint64_t blkid, nblks, i;
 554         uint32_t dbuf_flags;
 555         int err;
 556         zio_t *zio;
 557 
 558         ASSERT(length <= DMU_MAX_ACCESS);
 559 
 560         /*
 561          * Note: We directly notify the prefetch code of this read, so that
 562          * we can tell it about the multi-block read.  dbuf_read() only knows
 563          * about the one block it is accessing.
 564          */
 565         dbuf_flags = DB_RF_CANFAIL | DB_RF_NEVERWAIT | DB_RF_HAVESTRUCT |
 566             DB_RF_NOPREFETCH;
 567 
 568         rw_enter(&dn->dn_struct_rwlock, RW_READER);
 569         if (dn->dn_datablkshift) {
 570                 int blkshift = dn->dn_datablkshift;
 571                 nblks = (P2ROUNDUP(offset + length, 1ULL << blkshift) -
 572                     P2ALIGN(offset, 1ULL << blkshift)) >> blkshift;
 573         } else {
 574                 if (offset + length > dn->dn_datablksz) {
 575                         zfs_panic_recover("zfs: accessing past end of object "
 576                             "%llx/%llx (size=%u access=%llu+%llu)",
 577                             (longlong_t)dn->dn_objset->
 578                             os_dsl_dataset->ds_object,
 579                             (longlong_t)dn->dn_object, dn->dn_datablksz,
 580                             (longlong_t)offset, (longlong_t)length);
 581                         rw_exit(&dn->dn_struct_rwlock);
 582                         return (SET_ERROR(EIO));
 583                 }
 584                 nblks = 1;
 585         }
 586         dbp = kmem_zalloc(sizeof (dmu_buf_t *) * nblks, KM_SLEEP);
 587 
 588         zio = zio_root(dn->dn_objset->os_spa, NULL, NULL, ZIO_FLAG_CANFAIL);
 589         blkid = dbuf_whichblock(dn, 0, offset);
 590         for (i = 0; i < nblks; i++) {
 591                 dmu_buf_impl_t *db = dbuf_hold(dn, blkid + i, tag);
 592                 if (db == NULL) {
 593                         rw_exit(&dn->dn_struct_rwlock);
 594                         dmu_buf_rele_array(dbp, nblks, tag);
 595                         zio_nowait(zio);
 596                         return (SET_ERROR(EIO));
 597                 }
 598 
 599                 /* initiate async i/o */
 600                 if (read)
 601                         (void) dbuf_read(db, zio, dbuf_flags);
 602                 dbp[i] = &db->db;
 603         }
 604 
 605         if ((flags & DMU_READ_NO_PREFETCH) == 0 &&
 606             DNODE_META_IS_CACHEABLE(dn) && length <= zfetch_array_rd_sz) {
 607                 dmu_zfetch(&dn->dn_zfetch, blkid, nblks,
 608                     read && DNODE_IS_CACHEABLE(dn));
 609         }
 610         rw_exit(&dn->dn_struct_rwlock);
 611 
 612         /* wait for async i/o */
 613         err = zio_wait(zio);
 614         if (err) {
 615                 dmu_buf_rele_array(dbp, nblks, tag);
 616                 return (err);
 617         }
 618 
 619         /* wait for other io to complete */
 620         if (read) {
 621                 for (i = 0; i < nblks; i++) {
 622                         dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbp[i];
 623                         mutex_enter(&db->db_mtx);
 624                         while (db->db_state == DB_READ ||
 625                             db->db_state == DB_FILL)
 626                                 cv_wait(&db->db_changed, &db->db_mtx);
 627                         if (db->db_state == DB_UNCACHED)
 628                                 err = SET_ERROR(EIO);
 629                         mutex_exit(&db->db_mtx);
 630                         if (err) {
 631                                 dmu_buf_rele_array(dbp, nblks, tag);
 632                                 return (err);
 633                         }
 634                 }
 635         }
 636 
 637         *numbufsp = nblks;
 638         *dbpp = dbp;
 639         return (0);
 640 }
 641 
 642 static int
 643 dmu_buf_hold_array(objset_t *os, uint64_t object, uint64_t offset,
 644     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
 645 {
 646         dnode_t *dn;
 647         int err;
 648 
 649         err = dnode_hold(os, object, FTAG, &dn);
 650         if (err)
 651                 return (err);
 652 
 653         err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
 654             numbufsp, dbpp, DMU_READ_PREFETCH);
 655 
 656         dnode_rele(dn, FTAG);
 657 
 658         return (err);
 659 }
 660 
 661 int
 662 dmu_buf_hold_array_by_bonus(dmu_buf_t *db_fake, uint64_t offset,
 663     uint64_t length, boolean_t read, void *tag, int *numbufsp,
 664     dmu_buf_t ***dbpp)
 665 {
 666         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
 667         dnode_t *dn;
 668         int err;
 669 
 670         DB_DNODE_ENTER(db);
 671         dn = DB_DNODE(db);
 672         err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
 673             numbufsp, dbpp, DMU_READ_PREFETCH);
 674         DB_DNODE_EXIT(db);
 675 
 676         return (err);
 677 }
 678 
 679 void
 680 dmu_buf_rele_array(dmu_buf_t **dbp_fake, int numbufs, void *tag)
 681 {
 682         int i;
 683         dmu_buf_impl_t **dbp = (dmu_buf_impl_t **)dbp_fake;
 684 
 685         if (numbufs == 0)
 686                 return;
 687 
 688         for (i = 0; i < numbufs; i++) {
 689                 if (dbp[i])
 690                         dbuf_rele(dbp[i], tag);
 691         }
 692 
 693         kmem_free(dbp, sizeof (dmu_buf_t *) * numbufs);
 694 }
 695 
 696 /*
 697  * Issue prefetch i/os for the given blocks.  If level is greater than 0, the
 698  * indirect blocks prefeteched will be those that point to the blocks containing
 699  * the data starting at offset, and continuing to offset + len.
 700  *
 701  * Note that if the indirect blocks above the blocks being prefetched are not
 702  * in cache, they will be asychronously read in.
 703  */
 704 void
 705 dmu_prefetch(objset_t *os, uint64_t object, int64_t level, uint64_t offset,
 706     uint64_t len, zio_priority_t pri)
 707 {
 708         dnode_t *dn;
 709         uint64_t blkid;
 710         int nblks, err;
 711 
 712         if (len == 0) {  /* they're interested in the bonus buffer */
 713                 dn = DMU_META_DNODE(os);
 714 
 715                 if (object == 0 || object >= DN_MAX_OBJECT)
 716                         return;
 717 
 718                 rw_enter(&dn->dn_struct_rwlock, RW_READER);
 719                 blkid = dbuf_whichblock(dn, level,
 720                     object * sizeof (dnode_phys_t));
 721                 dbuf_prefetch(dn, level, blkid, pri, 0);
 722                 rw_exit(&dn->dn_struct_rwlock);
 723                 return;
 724         }
 725 
 726         /*
 727          * See comment before the definition of dmu_prefetch_max.
 728          */
 729         len = MIN(len, dmu_prefetch_max);
 730 
 731         /*
 732          * XXX - Note, if the dnode for the requested object is not
 733          * already cached, we will do a *synchronous* read in the
 734          * dnode_hold() call.  The same is true for any indirects.
 735          */
 736         err = dnode_hold(os, object, FTAG, &dn);
 737         if (err != 0)
 738                 return;
 739 
 740         rw_enter(&dn->dn_struct_rwlock, RW_READER);
 741         /*
 742          * offset + len - 1 is the last byte we want to prefetch for, and offset
 743          * is the first.  Then dbuf_whichblk(dn, level, off + len - 1) is the
 744          * last block we want to prefetch, and dbuf_whichblock(dn, level,
 745          * offset)  is the first.  Then the number we need to prefetch is the
 746          * last - first + 1.
 747          */
 748         if (level > 0 || dn->dn_datablkshift != 0) {
 749                 nblks = dbuf_whichblock(dn, level, offset + len - 1) -
 750                     dbuf_whichblock(dn, level, offset) + 1;
 751         } else {
 752                 nblks = (offset < dn->dn_datablksz);
 753         }
 754 
 755         if (nblks != 0) {
 756                 blkid = dbuf_whichblock(dn, level, offset);
 757                 for (int i = 0; i < nblks; i++)
 758                         dbuf_prefetch(dn, level, blkid + i, pri, 0);
 759         }
 760 
 761         rw_exit(&dn->dn_struct_rwlock);
 762 
 763         dnode_rele(dn, FTAG);
 764 }
 765 
 766 /*
 767  * Get the next "chunk" of file data to free.  We traverse the file from
 768  * the end so that the file gets shorter over time (if we crashes in the
 769  * middle, this will leave us in a better state).  We find allocated file
 770  * data by simply searching the allocated level 1 indirects.
 771  *
 772  * On input, *start should be the first offset that does not need to be
 773  * freed (e.g. "offset + length").  On return, *start will be the first
 774  * offset that should be freed.
 775  */
 776 static int
 777 get_next_chunk(dnode_t *dn, uint64_t *start, uint64_t minimum)
 778 {
 779         uint64_t maxblks = DMU_MAX_ACCESS >> (dn->dn_indblkshift + 1);
 780         /* bytes of data covered by a level-1 indirect block */
 781         uint64_t iblkrange =
 782             dn->dn_datablksz * EPB(dn->dn_indblkshift, SPA_BLKPTRSHIFT);
 783 
 784         ASSERT3U(minimum, <=, *start);
 785 
 786         if (*start - minimum <= iblkrange * maxblks) {
 787                 *start = minimum;
 788                 return (0);
 789         }
 790         ASSERT(ISP2(iblkrange));
 791 
 792         for (uint64_t blks = 0; *start > minimum && blks < maxblks; blks++) {
 793                 int err;
 794 
 795                 /*
 796                  * dnode_next_offset(BACKWARDS) will find an allocated L1
 797                  * indirect block at or before the input offset.  We must
 798                  * decrement *start so that it is at the end of the region
 799                  * to search.
 800                  */
 801                 (*start)--;
 802                 err = dnode_next_offset(dn,
 803                     DNODE_FIND_BACKWARDS, start, 2, 1, 0);
 804 
 805                 /* if there are no indirect blocks before start, we are done */
 806                 if (err == ESRCH) {
 807                         *start = minimum;
 808                         break;
 809                 } else if (err != 0) {
 810                         return (err);
 811                 }
 812 
 813                 /* set start to the beginning of this L1 indirect */
 814                 *start = P2ALIGN(*start, iblkrange);
 815         }
 816         if (*start < minimum)
 817                 *start = minimum;
 818         return (0);
 819 }
 820 
 821 /*
 822  * If this objset is of type OST_ZFS return true if vfs's unmounted flag is set,
 823  * otherwise return false.
 824  * Used below in dmu_free_long_range_impl() to enable abort when unmounting
 825  */
 826 /*ARGSUSED*/
 827 static boolean_t
 828 dmu_objset_zfs_unmounting(objset_t *os)
 829 {
 830 #ifdef _KERNEL
 831         if (dmu_objset_type(os) == DMU_OST_ZFS)
 832                 return (zfs_get_vfs_flag_unmounted(os));
 833 #endif
 834         return (B_FALSE);
 835 }
 836 
 837 static int
 838 dmu_free_long_range_impl(objset_t *os, dnode_t *dn, uint64_t offset,
 839     uint64_t length)
 840 {
 841         uint64_t object_size = (dn->dn_maxblkid + 1) * dn->dn_datablksz;
 842         int err;
 843         uint64_t dirty_frees_threshold;
 844         dsl_pool_t *dp = dmu_objset_pool(os);
 845 
 846         if (offset >= object_size)
 847                 return (0);
 848 
 849         if (zfs_per_txg_dirty_frees_percent <= 100)
 850                 dirty_frees_threshold =
 851                     zfs_per_txg_dirty_frees_percent * zfs_dirty_data_max / 100;
 852         else
 853                 dirty_frees_threshold = zfs_dirty_data_max / 4;
 854 
 855         if (length == DMU_OBJECT_END || offset + length > object_size)
 856                 length = object_size - offset;
 857 
 858         while (length != 0) {
 859                 uint64_t chunk_end, chunk_begin, chunk_len;
 860                 uint64_t long_free_dirty_all_txgs = 0;
 861                 dmu_tx_t *tx;
 862 
 863                 if (dmu_objset_zfs_unmounting(dn->dn_objset))
 864                         return (SET_ERROR(EINTR));
 865 
 866                 chunk_end = chunk_begin = offset + length;
 867 
 868                 /* move chunk_begin backwards to the beginning of this chunk */
 869                 err = get_next_chunk(dn, &chunk_begin, offset);
 870                 if (err)
 871                         return (err);
 872                 ASSERT3U(chunk_begin, >=, offset);
 873                 ASSERT3U(chunk_begin, <=, chunk_end);
 874 
 875                 chunk_len = chunk_end - chunk_begin;
 876 
 877                 mutex_enter(&dp->dp_lock);
 878                 for (int t = 0; t < TXG_SIZE; t++) {
 879                         long_free_dirty_all_txgs +=
 880                             dp->dp_long_free_dirty_pertxg[t];
 881                 }
 882                 mutex_exit(&dp->dp_lock);
 883 
 884                 /*
 885                  * To avoid filling up a TXG with just frees wait for
 886                  * the next TXG to open before freeing more chunks if
 887                  * we have reached the threshold of frees
 888                  */
 889                 if (dirty_frees_threshold != 0 &&
 890                     long_free_dirty_all_txgs >= dirty_frees_threshold) {
 891                         txg_wait_open(dp, 0);
 892                         continue;
 893                 }
 894 
 895                 tx = dmu_tx_create(os);
 896                 dmu_tx_hold_free(tx, dn->dn_object, chunk_begin, chunk_len);
 897 
 898                 /*
 899                  * Mark this transaction as typically resulting in a net
 900                  * reduction in space used.
 901                  */
 902                 dmu_tx_mark_netfree(tx);
 903                 err = dmu_tx_assign(tx, TXG_WAIT);
 904                 if (err) {
 905                         dmu_tx_abort(tx);
 906                         return (err);
 907                 }
 908 
 909                 mutex_enter(&dp->dp_lock);
 910                 dp->dp_long_free_dirty_pertxg[dmu_tx_get_txg(tx) & TXG_MASK] +=
 911                     chunk_len;
 912                 mutex_exit(&dp->dp_lock);
 913                 DTRACE_PROBE3(free__long__range,
 914                     uint64_t, long_free_dirty_all_txgs, uint64_t, chunk_len,
 915                     uint64_t, dmu_tx_get_txg(tx));
 916                 dnode_free_range(dn, chunk_begin, chunk_len, tx);
 917 
 918                 dmu_tx_commit(tx);
 919 
 920                 length -= chunk_len;
 921         }
 922         return (0);
 923 }
 924 
 925 int
 926 dmu_free_long_range(objset_t *os, uint64_t object,
 927     uint64_t offset, uint64_t length)
 928 {
 929         dnode_t *dn;
 930         int err;
 931 
 932         err = dnode_hold(os, object, FTAG, &dn);
 933         if (err != 0)
 934                 return (err);
 935         err = dmu_free_long_range_impl(os, dn, offset, length);
 936 
 937         /*
 938          * It is important to zero out the maxblkid when freeing the entire
 939          * file, so that (a) subsequent calls to dmu_free_long_range_impl()
 940          * will take the fast path, and (b) dnode_reallocate() can verify
 941          * that the entire file has been freed.
 942          */
 943         if (err == 0 && offset == 0 && length == DMU_OBJECT_END)
 944                 dn->dn_maxblkid = 0;
 945 
 946         dnode_rele(dn, FTAG);
 947         return (err);
 948 }
 949 
 950 int
 951 dmu_free_long_object(objset_t *os, uint64_t object)
 952 {
 953         dmu_tx_t *tx;
 954         int err;
 955 
 956         err = dmu_free_long_range(os, object, 0, DMU_OBJECT_END);
 957         if (err != 0)
 958                 return (err);
 959 
 960         tx = dmu_tx_create(os);
 961         dmu_tx_hold_bonus(tx, object);
 962         dmu_tx_hold_free(tx, object, 0, DMU_OBJECT_END);
 963         dmu_tx_mark_netfree(tx);
 964         err = dmu_tx_assign(tx, TXG_WAIT);
 965         if (err == 0) {
 966                 if (err == 0)
 967                         err = dmu_object_free(os, object, tx);
 968 
 969                 dmu_tx_commit(tx);
 970         } else {
 971                 dmu_tx_abort(tx);
 972         }
 973 
 974         return (err);
 975 }
 976 
 977 int
 978 dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
 979     uint64_t size, dmu_tx_t *tx)
 980 {
 981         dnode_t *dn;
 982         int err = dnode_hold(os, object, FTAG, &dn);
 983         if (err)
 984                 return (err);
 985         ASSERT(offset < UINT64_MAX);
 986         ASSERT(size == DMU_OBJECT_END || size <= UINT64_MAX - offset);
 987         dnode_free_range(dn, offset, size, tx);
 988         dnode_rele(dn, FTAG);
 989         return (0);
 990 }
 991 
 992 static int
 993 dmu_read_impl(dnode_t *dn, uint64_t offset, uint64_t size,
 994     void *buf, uint32_t flags)
 995 {
 996         dmu_buf_t **dbp;
 997         int numbufs, err = 0;
 998 
 999         /*
1000          * Deal with odd block sizes, where there can't be data past the first
1001          * block.  If we ever do the tail block optimization, we will need to
1002          * handle that here as well.
1003          */
1004         if (dn->dn_maxblkid == 0) {
1005                 int newsz = offset > dn->dn_datablksz ? 0 :
1006                     MIN(size, dn->dn_datablksz - offset);
1007                 bzero((char *)buf + newsz, size - newsz);
1008                 size = newsz;
1009         }
1010 
1011         while (size > 0) {
1012                 uint64_t mylen = MIN(size, DMU_MAX_ACCESS / 2);
1013                 int i;
1014 
1015                 /*
1016                  * NB: we could do this block-at-a-time, but it's nice
1017                  * to be reading in parallel.
1018                  */
1019                 err = dmu_buf_hold_array_by_dnode(dn, offset, mylen,
1020                     TRUE, FTAG, &numbufs, &dbp, flags);
1021                 if (err)
1022                         break;
1023 
1024                 for (i = 0; i < numbufs; i++) {
1025                         int tocpy;
1026                         int bufoff;
1027                         dmu_buf_t *db = dbp[i];
1028 
1029                         ASSERT(size > 0);
1030 
1031                         bufoff = offset - db->db_offset;
1032                         tocpy = (int)MIN(db->db_size - bufoff, size);
1033 
1034                         bcopy((char *)db->db_data + bufoff, buf, tocpy);
1035 
1036                         offset += tocpy;
1037                         size -= tocpy;
1038                         buf = (char *)buf + tocpy;
1039                 }
1040                 dmu_buf_rele_array(dbp, numbufs, FTAG);
1041         }
1042         return (err);
1043 }
1044 
1045 int
1046 dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
1047     void *buf, uint32_t flags)
1048 {
1049         dnode_t *dn;
1050         int err;
1051 
1052         err = dnode_hold(os, object, FTAG, &dn);
1053         if (err != 0)
1054                 return (err);
1055 
1056         err = dmu_read_impl(dn, offset, size, buf, flags);
1057         dnode_rele(dn, FTAG);
1058         return (err);
1059 }
1060 
1061 int
1062 dmu_read_by_dnode(dnode_t *dn, uint64_t offset, uint64_t size, void *buf,
1063     uint32_t flags)
1064 {
1065         return (dmu_read_impl(dn, offset, size, buf, flags));
1066 }
1067 
1068 static void
1069 dmu_write_impl(dmu_buf_t **dbp, int numbufs, uint64_t offset, uint64_t size,
1070     const void *buf, dmu_tx_t *tx)
1071 {
1072         int i;
1073 
1074         for (i = 0; i < numbufs; i++) {
1075                 int tocpy;
1076                 int bufoff;
1077                 dmu_buf_t *db = dbp[i];
1078 
1079                 ASSERT(size > 0);
1080 
1081                 bufoff = offset - db->db_offset;
1082                 tocpy = (int)MIN(db->db_size - bufoff, size);
1083 
1084                 ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
1085 
1086                 if (tocpy == db->db_size)
1087                         dmu_buf_will_fill(db, tx);
1088                 else
1089                         dmu_buf_will_dirty(db, tx);
1090 
1091                 bcopy(buf, (char *)db->db_data + bufoff, tocpy);
1092 
1093                 if (tocpy == db->db_size)
1094                         dmu_buf_fill_done(db, tx);
1095 
1096                 offset += tocpy;
1097                 size -= tocpy;
1098                 buf = (char *)buf + tocpy;
1099         }
1100 }
1101 
1102 void
1103 dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
1104     const void *buf, dmu_tx_t *tx)
1105 {
1106         dmu_buf_t **dbp;
1107         int numbufs;
1108 
1109         if (size == 0)
1110                 return;
1111 
1112         VERIFY0(dmu_buf_hold_array(os, object, offset, size,
1113             FALSE, FTAG, &numbufs, &dbp));
1114         dmu_write_impl(dbp, numbufs, offset, size, buf, tx);
1115         dmu_buf_rele_array(dbp, numbufs, FTAG);
1116 }
1117 
1118 void
1119 dmu_write_by_dnode(dnode_t *dn, uint64_t offset, uint64_t size,
1120     const void *buf, dmu_tx_t *tx)
1121 {
1122         dmu_buf_t **dbp;
1123         int numbufs;
1124 
1125         if (size == 0)
1126                 return;
1127 
1128         VERIFY0(dmu_buf_hold_array_by_dnode(dn, offset, size,
1129             FALSE, FTAG, &numbufs, &dbp, DMU_READ_PREFETCH));
1130         dmu_write_impl(dbp, numbufs, offset, size, buf, tx);
1131         dmu_buf_rele_array(dbp, numbufs, FTAG);
1132 }
1133 
1134 static int
1135 dmu_object_remap_one_indirect(objset_t *os, dnode_t *dn,
1136     uint64_t last_removal_txg, uint64_t offset)
1137 {
1138         uint64_t l1blkid = dbuf_whichblock(dn, 1, offset);
1139         int err = 0;
1140 
1141         rw_enter(&dn->dn_struct_rwlock, RW_READER);
1142         dmu_buf_impl_t *dbuf = dbuf_hold_level(dn, 1, l1blkid, FTAG);
1143         ASSERT3P(dbuf, !=, NULL);
1144 
1145         /*
1146          * If the block hasn't been written yet, this default will ensure
1147          * we don't try to remap it.
1148          */
1149         uint64_t birth = UINT64_MAX;
1150         ASSERT3U(last_removal_txg, !=, UINT64_MAX);
1151         if (dbuf->db_blkptr != NULL)
1152                 birth = dbuf->db_blkptr->blk_birth;
1153         rw_exit(&dn->dn_struct_rwlock);
1154 
1155         /*
1156          * If this L1 was already written after the last removal, then we've
1157          * already tried to remap it.
1158          */
1159         if (birth <= last_removal_txg &&
1160             dbuf_read(dbuf, NULL, DB_RF_MUST_SUCCEED) == 0 &&
1161             dbuf_can_remap(dbuf)) {
1162                 dmu_tx_t *tx = dmu_tx_create(os);
1163                 dmu_tx_hold_remap_l1indirect(tx, dn->dn_object);
1164                 err = dmu_tx_assign(tx, TXG_WAIT);
1165                 if (err == 0) {
1166                         (void) dbuf_dirty(dbuf, tx);
1167                         dmu_tx_commit(tx);
1168                 } else {
1169                         dmu_tx_abort(tx);
1170                 }
1171         }
1172 
1173         dbuf_rele(dbuf, FTAG);
1174 
1175         delay(zfs_object_remap_one_indirect_delay_ticks);
1176 
1177         return (err);
1178 }
1179 
1180 /*
1181  * Remap all blockpointers in the object, if possible, so that they reference
1182  * only concrete vdevs.
1183  *
1184  * To do this, iterate over the L0 blockpointers and remap any that reference
1185  * an indirect vdev. Note that we only examine L0 blockpointers; since we
1186  * cannot guarantee that we can remap all blockpointer anyways (due to split
1187  * blocks), we do not want to make the code unnecessarily complicated to
1188  * catch the unlikely case that there is an L1 block on an indirect vdev that
1189  * contains no indirect blockpointers.
1190  */
1191 int
1192 dmu_object_remap_indirects(objset_t *os, uint64_t object,
1193     uint64_t last_removal_txg)
1194 {
1195         uint64_t offset, l1span;
1196         int err;
1197         dnode_t *dn;
1198 
1199         err = dnode_hold(os, object, FTAG, &dn);
1200         if (err != 0) {
1201                 return (err);
1202         }
1203 
1204         if (dn->dn_nlevels <= 1) {
1205                 if (issig(JUSTLOOKING) && issig(FORREAL)) {
1206                         err = SET_ERROR(EINTR);
1207                 }
1208 
1209                 /*
1210                  * If the dnode has no indirect blocks, we cannot dirty them.
1211                  * We still want to remap the blkptr(s) in the dnode if
1212                  * appropriate, so mark it as dirty.
1213                  */
1214                 if (err == 0 && dnode_needs_remap(dn)) {
1215                         dmu_tx_t *tx = dmu_tx_create(os);
1216                         dmu_tx_hold_bonus(tx, dn->dn_object);
1217                         if ((err = dmu_tx_assign(tx, TXG_WAIT)) == 0) {
1218                                 dnode_setdirty(dn, tx);
1219                                 dmu_tx_commit(tx);
1220                         } else {
1221                                 dmu_tx_abort(tx);
1222                         }
1223                 }
1224 
1225                 dnode_rele(dn, FTAG);
1226                 return (err);
1227         }
1228 
1229         offset = 0;
1230         l1span = 1ULL << (dn->dn_indblkshift - SPA_BLKPTRSHIFT +
1231             dn->dn_datablkshift);
1232         /*
1233          * Find the next L1 indirect that is not a hole.
1234          */
1235         while (dnode_next_offset(dn, 0, &offset, 2, 1, 0) == 0) {
1236                 if (issig(JUSTLOOKING) && issig(FORREAL)) {
1237                         err = SET_ERROR(EINTR);
1238                         break;
1239                 }
1240                 if ((err = dmu_object_remap_one_indirect(os, dn,
1241                     last_removal_txg, offset)) != 0) {
1242                         break;
1243                 }
1244                 offset += l1span;
1245         }
1246 
1247         dnode_rele(dn, FTAG);
1248         return (err);
1249 }
1250 
1251 void
1252 dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
1253     dmu_tx_t *tx)
1254 {
1255         dmu_buf_t **dbp;
1256         int numbufs, i;
1257 
1258         if (size == 0)
1259                 return;
1260 
1261         VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
1262             FALSE, FTAG, &numbufs, &dbp));
1263 
1264         for (i = 0; i < numbufs; i++) {
1265                 dmu_buf_t *db = dbp[i];
1266 
1267                 dmu_buf_will_not_fill(db, tx);
1268         }
1269         dmu_buf_rele_array(dbp, numbufs, FTAG);
1270 }
1271 
1272 void
1273 dmu_write_embedded(objset_t *os, uint64_t object, uint64_t offset,
1274     void *data, uint8_t etype, uint8_t comp, int uncompressed_size,
1275     int compressed_size, int byteorder, dmu_tx_t *tx)
1276 {
1277         dmu_buf_t *db;
1278 
1279         ASSERT3U(etype, <, NUM_BP_EMBEDDED_TYPES);
1280         ASSERT3U(comp, <, ZIO_COMPRESS_FUNCTIONS);
1281         VERIFY0(dmu_buf_hold_noread(os, object, offset,
1282             FTAG, &db));
1283 
1284         dmu_buf_write_embedded(db,
1285             data, (bp_embedded_type_t)etype, (enum zio_compress)comp,
1286             uncompressed_size, compressed_size, byteorder, tx);
1287 
1288         dmu_buf_rele(db, FTAG);
1289 }
1290 
1291 /*
1292  * DMU support for xuio
1293  */
1294 kstat_t *xuio_ksp = NULL;
1295 
1296 int
1297 dmu_xuio_init(xuio_t *xuio, int nblk)
1298 {
1299         dmu_xuio_t *priv;
1300         uio_t *uio = &xuio->xu_uio;
1301 
1302         uio->uio_iovcnt = nblk;
1303         uio->uio_iov = kmem_zalloc(nblk * sizeof (iovec_t), KM_SLEEP);
1304 
1305         priv = kmem_zalloc(sizeof (dmu_xuio_t), KM_SLEEP);
1306         priv->cnt = nblk;
1307         priv->bufs = kmem_zalloc(nblk * sizeof (arc_buf_t *), KM_SLEEP);
1308         priv->iovp = uio->uio_iov;
1309         XUIO_XUZC_PRIV(xuio) = priv;
1310 
1311         if (XUIO_XUZC_RW(xuio) == UIO_READ)
1312                 XUIOSTAT_INCR(xuiostat_onloan_rbuf, nblk);
1313         else
1314                 XUIOSTAT_INCR(xuiostat_onloan_wbuf, nblk);
1315 
1316         return (0);
1317 }
1318 
1319 void
1320 dmu_xuio_fini(xuio_t *xuio)
1321 {
1322         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
1323         int nblk = priv->cnt;
1324 
1325         kmem_free(priv->iovp, nblk * sizeof (iovec_t));
1326         kmem_free(priv->bufs, nblk * sizeof (arc_buf_t *));
1327         kmem_free(priv, sizeof (dmu_xuio_t));
1328 
1329         if (XUIO_XUZC_RW(xuio) == UIO_READ)
1330                 XUIOSTAT_INCR(xuiostat_onloan_rbuf, -nblk);
1331         else
1332                 XUIOSTAT_INCR(xuiostat_onloan_wbuf, -nblk);
1333 }
1334 
1335 /*
1336  * Initialize iov[priv->next] and priv->bufs[priv->next] with { off, n, abuf }
1337  * and increase priv->next by 1.
1338  */
1339 int
1340 dmu_xuio_add(xuio_t *xuio, arc_buf_t *abuf, offset_t off, size_t n)
1341 {
1342         struct iovec *iov;
1343         uio_t *uio = &xuio->xu_uio;
1344         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
1345         int i = priv->next++;
1346 
1347         ASSERT(i < priv->cnt);
1348         ASSERT(off + n <= arc_buf_lsize(abuf));
1349         iov = uio->uio_iov + i;
1350         iov->iov_base = (char *)abuf->b_data + off;
1351         iov->iov_len = n;
1352         priv->bufs[i] = abuf;
1353         return (0);
1354 }
1355 
1356 int
1357 dmu_xuio_cnt(xuio_t *xuio)
1358 {
1359         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
1360         return (priv->cnt);
1361 }
1362 
1363 arc_buf_t *
1364 dmu_xuio_arcbuf(xuio_t *xuio, int i)
1365 {
1366         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
1367 
1368         ASSERT(i < priv->cnt);
1369         return (priv->bufs[i]);
1370 }
1371 
1372 void
1373 dmu_xuio_clear(xuio_t *xuio, int i)
1374 {
1375         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
1376 
1377         ASSERT(i < priv->cnt);
1378         priv->bufs[i] = NULL;
1379 }
1380 
1381 static void
1382 xuio_stat_init(void)
1383 {
1384         xuio_ksp = kstat_create("zfs", 0, "xuio_stats", "misc",
1385             KSTAT_TYPE_NAMED, sizeof (xuio_stats) / sizeof (kstat_named_t),
1386             KSTAT_FLAG_VIRTUAL);
1387         if (xuio_ksp != NULL) {
1388                 xuio_ksp->ks_data = &xuio_stats;
1389                 kstat_install(xuio_ksp);
1390         }
1391 }
1392 
1393 static void
1394 xuio_stat_fini(void)
1395 {
1396         if (xuio_ksp != NULL) {
1397                 kstat_delete(xuio_ksp);
1398                 xuio_ksp = NULL;
1399         }
1400 }
1401 
1402 void
1403 xuio_stat_wbuf_copied(void)
1404 {
1405         XUIOSTAT_BUMP(xuiostat_wbuf_copied);
1406 }
1407 
1408 void
1409 xuio_stat_wbuf_nocopy(void)
1410 {
1411         XUIOSTAT_BUMP(xuiostat_wbuf_nocopy);
1412 }
1413 
1414 #ifdef _KERNEL
1415 int
1416 dmu_read_uio_dnode(dnode_t *dn, uio_t *uio, uint64_t size)
1417 {
1418         dmu_buf_t **dbp;
1419         int numbufs, i, err;
1420         xuio_t *xuio = NULL;
1421 
1422         /*
1423          * NB: we could do this block-at-a-time, but it's nice
1424          * to be reading in parallel.
1425          */
1426         err = dmu_buf_hold_array_by_dnode(dn, uio->uio_loffset, size,
1427             TRUE, FTAG, &numbufs, &dbp, 0);
1428         if (err)
1429                 return (err);
1430 
1431         if (uio->uio_extflg == UIO_XUIO)
1432                 xuio = (xuio_t *)uio;
1433 
1434         for (i = 0; i < numbufs; i++) {
1435                 int tocpy;
1436                 int bufoff;
1437                 dmu_buf_t *db = dbp[i];
1438 
1439                 ASSERT(size > 0);
1440 
1441                 bufoff = uio->uio_loffset - db->db_offset;
1442                 tocpy = (int)MIN(db->db_size - bufoff, size);
1443 
1444                 if (xuio) {
1445                         dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
1446                         arc_buf_t *dbuf_abuf = dbi->db_buf;
1447                         arc_buf_t *abuf = dbuf_loan_arcbuf(dbi);
1448                         err = dmu_xuio_add(xuio, abuf, bufoff, tocpy);
1449                         if (!err) {
1450                                 uio->uio_resid -= tocpy;
1451                                 uio->uio_loffset += tocpy;
1452                         }
1453 
1454                         if (abuf == dbuf_abuf)
1455                                 XUIOSTAT_BUMP(xuiostat_rbuf_nocopy);
1456                         else
1457                                 XUIOSTAT_BUMP(xuiostat_rbuf_copied);
1458                 } else {
1459                         err = uiomove((char *)db->db_data + bufoff, tocpy,
1460                             UIO_READ, uio);
1461                 }
1462                 if (err)
1463                         break;
1464 
1465                 size -= tocpy;
1466         }
1467         dmu_buf_rele_array(dbp, numbufs, FTAG);
1468 
1469         return (err);
1470 }
1471 
1472 /*
1473  * Read 'size' bytes into the uio buffer.
1474  * From object zdb->db_object.
1475  * Starting at offset uio->uio_loffset.
1476  *
1477  * If the caller already has a dbuf in the target object
1478  * (e.g. its bonus buffer), this routine is faster than dmu_read_uio(),
1479  * because we don't have to find the dnode_t for the object.
1480  */
1481 int
1482 dmu_read_uio_dbuf(dmu_buf_t *zdb, uio_t *uio, uint64_t size)
1483 {
1484         dmu_buf_impl_t *db = (dmu_buf_impl_t *)zdb;
1485         dnode_t *dn;
1486         int err;
1487 
1488         if (size == 0)
1489                 return (0);
1490 
1491         DB_DNODE_ENTER(db);
1492         dn = DB_DNODE(db);
1493         err = dmu_read_uio_dnode(dn, uio, size);
1494         DB_DNODE_EXIT(db);
1495 
1496         return (err);
1497 }
1498 
1499 /*
1500  * Read 'size' bytes into the uio buffer.
1501  * From the specified object
1502  * Starting at offset uio->uio_loffset.
1503  */
1504 int
1505 dmu_read_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size)
1506 {
1507         dnode_t *dn;
1508         int err;
1509 
1510         if (size == 0)
1511                 return (0);
1512 
1513         err = dnode_hold(os, object, FTAG, &dn);
1514         if (err)
1515                 return (err);
1516 
1517         err = dmu_read_uio_dnode(dn, uio, size);
1518 
1519         dnode_rele(dn, FTAG);
1520 
1521         return (err);
1522 }
1523 
1524 int
1525 dmu_write_uio_dnode(dnode_t *dn, uio_t *uio, uint64_t size, dmu_tx_t *tx)
1526 {
1527         dmu_buf_t **dbp;
1528         int numbufs;
1529         int err = 0;
1530         int i;
1531 
1532         err = dmu_buf_hold_array_by_dnode(dn, uio->uio_loffset, size,
1533             FALSE, FTAG, &numbufs, &dbp, DMU_READ_PREFETCH);
1534         if (err)
1535                 return (err);
1536 
1537         for (i = 0; i < numbufs; i++) {
1538                 int tocpy;
1539                 int bufoff;
1540                 dmu_buf_t *db = dbp[i];
1541 
1542                 ASSERT(size > 0);
1543 
1544                 bufoff = uio->uio_loffset - db->db_offset;
1545                 tocpy = (int)MIN(db->db_size - bufoff, size);
1546 
1547                 ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
1548 
1549                 if (tocpy == db->db_size)
1550                         dmu_buf_will_fill(db, tx);
1551                 else
1552                         dmu_buf_will_dirty(db, tx);
1553 
1554                 /*
1555                  * XXX uiomove could block forever (eg. nfs-backed
1556                  * pages).  There needs to be a uiolockdown() function
1557                  * to lock the pages in memory, so that uiomove won't
1558                  * block.
1559                  */
1560                 err = uiomove((char *)db->db_data + bufoff, tocpy,
1561                     UIO_WRITE, uio);
1562 
1563                 if (tocpy == db->db_size)
1564                         dmu_buf_fill_done(db, tx);
1565 
1566                 if (err)
1567                         break;
1568 
1569                 size -= tocpy;
1570         }
1571 
1572         dmu_buf_rele_array(dbp, numbufs, FTAG);
1573         return (err);
1574 }
1575 
1576 /*
1577  * Write 'size' bytes from the uio buffer.
1578  * To object zdb->db_object.
1579  * Starting at offset uio->uio_loffset.
1580  *
1581  * If the caller already has a dbuf in the target object
1582  * (e.g. its bonus buffer), this routine is faster than dmu_write_uio(),
1583  * because we don't have to find the dnode_t for the object.
1584  */
1585 int
1586 dmu_write_uio_dbuf(dmu_buf_t *zdb, uio_t *uio, uint64_t size,
1587     dmu_tx_t *tx)
1588 {
1589         dmu_buf_impl_t *db = (dmu_buf_impl_t *)zdb;
1590         dnode_t *dn;
1591         int err;
1592 
1593         if (size == 0)
1594                 return (0);
1595 
1596         DB_DNODE_ENTER(db);
1597         dn = DB_DNODE(db);
1598         err = dmu_write_uio_dnode(dn, uio, size, tx);
1599         DB_DNODE_EXIT(db);
1600 
1601         return (err);
1602 }
1603 
1604 /*
1605  * Write 'size' bytes from the uio buffer.
1606  * To the specified object.
1607  * Starting at offset uio->uio_loffset.
1608  */
1609 int
1610 dmu_write_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size,
1611     dmu_tx_t *tx)
1612 {
1613         dnode_t *dn;
1614         int err;
1615 
1616         if (size == 0)
1617                 return (0);
1618 
1619         err = dnode_hold(os, object, FTAG, &dn);
1620         if (err)
1621                 return (err);
1622 
1623         err = dmu_write_uio_dnode(dn, uio, size, tx);
1624 
1625         dnode_rele(dn, FTAG);
1626 
1627         return (err);
1628 }
1629 
1630 int
1631 dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
1632     page_t *pp, dmu_tx_t *tx)
1633 {
1634         dmu_buf_t **dbp;
1635         int numbufs, i;
1636         int err;
1637 
1638         if (size == 0)
1639                 return (0);
1640 
1641         err = dmu_buf_hold_array(os, object, offset, size,
1642             FALSE, FTAG, &numbufs, &dbp);
1643         if (err)
1644                 return (err);
1645 
1646         for (i = 0; i < numbufs; i++) {
1647                 int tocpy, copied, thiscpy;
1648                 int bufoff;
1649                 dmu_buf_t *db = dbp[i];
1650                 caddr_t va;
1651 
1652                 ASSERT(size > 0);
1653                 ASSERT3U(db->db_size, >=, PAGESIZE);
1654 
1655                 bufoff = offset - db->db_offset;
1656                 tocpy = (int)MIN(db->db_size - bufoff, size);
1657 
1658                 ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
1659 
1660                 if (tocpy == db->db_size)
1661                         dmu_buf_will_fill(db, tx);
1662                 else
1663                         dmu_buf_will_dirty(db, tx);
1664 
1665                 for (copied = 0; copied < tocpy; copied += PAGESIZE) {
1666                         ASSERT3U(pp->p_offset, ==, db->db_offset + bufoff);
1667                         thiscpy = MIN(PAGESIZE, tocpy - copied);
1668                         va = zfs_map_page(pp, S_READ);
1669                         bcopy(va, (char *)db->db_data + bufoff, thiscpy);
1670                         zfs_unmap_page(pp, va);
1671                         pp = pp->p_next;
1672                         bufoff += PAGESIZE;
1673                 }
1674 
1675                 if (tocpy == db->db_size)
1676                         dmu_buf_fill_done(db, tx);
1677 
1678                 offset += tocpy;
1679                 size -= tocpy;
1680         }
1681         dmu_buf_rele_array(dbp, numbufs, FTAG);
1682         return (err);
1683 }
1684 #endif
1685 
1686 /*
1687  * Allocate a loaned anonymous arc buffer.
1688  */
1689 arc_buf_t *
1690 dmu_request_arcbuf(dmu_buf_t *handle, int size)
1691 {
1692         dmu_buf_impl_t *db = (dmu_buf_impl_t *)handle;
1693 
1694         return (arc_loan_buf(db->db_objset->os_spa, B_FALSE, size));
1695 }
1696 
1697 /*
1698  * Free a loaned arc buffer.
1699  */
1700 void
1701 dmu_return_arcbuf(arc_buf_t *buf)
1702 {
1703         arc_return_buf(buf, FTAG);
1704         arc_buf_destroy(buf, FTAG);
1705 }
1706 
1707 void
1708 dmu_copy_from_buf(objset_t *os, uint64_t object, uint64_t offset,
1709     dmu_buf_t *handle, dmu_tx_t *tx)
1710 {
1711         dmu_buf_t *dst_handle;
1712         dmu_buf_impl_t *dstdb;
1713         dmu_buf_impl_t *srcdb = (dmu_buf_impl_t *)handle;
1714         dmu_object_type_t type;
1715         arc_buf_t *abuf;
1716         uint64_t datalen;
1717         boolean_t byteorder;
1718         uint8_t salt[ZIO_DATA_SALT_LEN];
1719         uint8_t iv[ZIO_DATA_IV_LEN];
1720         uint8_t mac[ZIO_DATA_MAC_LEN];
1721 
1722         ASSERT3P(srcdb->db_buf, !=, NULL);
1723 
1724         /* hold the db that we want to write to */
1725         VERIFY0(dmu_buf_hold(os, object, offset, FTAG, &dst_handle,
1726             DMU_READ_NO_DECRYPT));
1727         dstdb = (dmu_buf_impl_t *)dst_handle;
1728         datalen = arc_buf_size(srcdb->db_buf);
1729 
1730         DB_DNODE_ENTER(dstdb);
1731         type = DB_DNODE(dstdb)->dn_type;
1732         DB_DNODE_EXIT(dstdb);
1733 
1734         /* allocated an arc buffer that matches the type of srcdb->db_buf */
1735         if (arc_is_encrypted(srcdb->db_buf)) {
1736                 arc_get_raw_params(srcdb->db_buf, &byteorder, salt, iv, mac);
1737                 abuf = arc_loan_raw_buf(os->os_spa, dmu_objset_id(os),
1738                     byteorder, salt, iv, mac, type,
1739                     datalen, arc_buf_lsize(srcdb->db_buf),
1740                     arc_get_compression(srcdb->db_buf));
1741         } else {
1742                 /* we won't get a compressed db back from dmu_buf_hold() */
1743                 ASSERT3U(arc_get_compression(srcdb->db_buf),
1744                     ==, ZIO_COMPRESS_OFF);
1745                 abuf = arc_loan_buf(os->os_spa,
1746                     DMU_OT_IS_METADATA(type), datalen);
1747         }
1748 
1749         ASSERT3U(datalen, ==, arc_buf_size(abuf));
1750 
1751         /* copy the data to the new buffer and assign it to the dstdb */
1752         bcopy(srcdb->db_buf->b_data, abuf->b_data, datalen);
1753         dbuf_assign_arcbuf(dstdb, abuf, tx);
1754         dmu_buf_rele(dst_handle, FTAG);
1755 }
1756 
1757 /*
1758  * When possible directly assign passed loaned arc buffer to a dbuf.
1759  * If this is not possible copy the contents of passed arc buf via
1760  * dmu_write().
1761  */
1762 int
1763 dmu_assign_arcbuf_by_dnode(dnode_t *dn, uint64_t offset, arc_buf_t *buf,
1764     dmu_tx_t *tx)
1765 {
1766         dmu_buf_impl_t *db;
1767         objset_t *os = dn->dn_objset;
1768         uint64_t object = dn->dn_object;
1769         uint32_t blksz = (uint32_t)arc_buf_lsize(buf);
1770         uint64_t blkid;
1771 
1772         rw_enter(&dn->dn_struct_rwlock, RW_READER);
1773         blkid = dbuf_whichblock(dn, 0, offset);
1774         db = dbuf_hold(dn, blkid, FTAG);
1775         if (db == NULL)
1776                 return (SET_ERROR(EIO));
1777         rw_exit(&dn->dn_struct_rwlock);
1778 
1779         /*
1780          * We can only assign if the offset is aligned, the arc buf is the
1781          * same size as the dbuf, and the dbuf is not metadata.
1782          */
1783         if (offset == db->db.db_offset && blksz == db->db.db_size) {
1784                 dbuf_assign_arcbuf(db, buf, tx);
1785                 dbuf_rele(db, FTAG);
1786         } else {
1787                 /* compressed bufs must always be assignable to their dbuf */
1788                 ASSERT3U(arc_get_compression(buf), ==, ZIO_COMPRESS_OFF);
1789                 ASSERT(!(buf->b_flags & ARC_BUF_FLAG_COMPRESSED));
1790 
1791                 os = dn->dn_objset;
1792                 object = dn->dn_object;
1793                 dbuf_rele(db, FTAG);
1794                 dmu_write(os, object, offset, blksz, buf->b_data, tx);
1795                 dmu_return_arcbuf(buf);
1796                 XUIOSTAT_BUMP(xuiostat_wbuf_copied);
1797         }
1798 
1799         return (0);
1800 }
1801 
1802 int
1803 dmu_assign_arcbuf_by_dbuf(dmu_buf_t *handle, uint64_t offset, arc_buf_t *buf,
1804     dmu_tx_t *tx)
1805 {
1806         int err;
1807         dmu_buf_impl_t *dbuf = (dmu_buf_impl_t *)handle;
1808 
1809         DB_DNODE_ENTER(dbuf);
1810         err = dmu_assign_arcbuf_by_dnode(DB_DNODE(dbuf), offset, buf, tx);
1811         DB_DNODE_EXIT(dbuf);
1812 
1813         return (err);
1814 }
1815 
1816 typedef struct {
1817         dbuf_dirty_record_t     *dsa_dr;
1818         dmu_sync_cb_t           *dsa_done;
1819         zgd_t                   *dsa_zgd;
1820         dmu_tx_t                *dsa_tx;
1821 } dmu_sync_arg_t;
1822 
1823 /* ARGSUSED */
1824 static void
1825 dmu_sync_ready(zio_t *zio, arc_buf_t *buf, void *varg)
1826 {
1827         dmu_sync_arg_t *dsa = varg;
1828         dmu_buf_t *db = dsa->dsa_zgd->zgd_db;
1829         blkptr_t *bp = zio->io_bp;
1830 
1831         if (zio->io_error == 0) {
1832                 if (BP_IS_HOLE(bp)) {
1833                         /*
1834                          * A block of zeros may compress to a hole, but the
1835                          * block size still needs to be known for replay.
1836                          */
1837                         BP_SET_LSIZE(bp, db->db_size);
1838                 } else if (!BP_IS_EMBEDDED(bp)) {
1839                         ASSERT(BP_GET_LEVEL(bp) == 0);
1840                         BP_SET_FILL(bp, 1);
1841                 }
1842         }
1843 }
1844 
1845 static void
1846 dmu_sync_late_arrival_ready(zio_t *zio)
1847 {
1848         dmu_sync_ready(zio, NULL, zio->io_private);
1849 }
1850 
1851 /* ARGSUSED */
1852 static void
1853 dmu_sync_done(zio_t *zio, arc_buf_t *buf, void *varg)
1854 {
1855         dmu_sync_arg_t *dsa = varg;
1856         dbuf_dirty_record_t *dr = dsa->dsa_dr;
1857         dmu_buf_impl_t *db = dr->dr_dbuf;
1858         zgd_t *zgd = dsa->dsa_zgd;
1859 
1860         /*
1861          * Record the vdev(s) backing this blkptr so they can be flushed after
1862          * the writes for the lwb have completed.
1863          */
1864         if (zio->io_error == 0) {
1865                 zil_lwb_add_block(zgd->zgd_lwb, zgd->zgd_bp);
1866         }
1867 
1868         mutex_enter(&db->db_mtx);
1869         ASSERT(dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC);
1870         if (zio->io_error == 0) {
1871                 dr->dt.dl.dr_nopwrite = !!(zio->io_flags & ZIO_FLAG_NOPWRITE);
1872                 if (dr->dt.dl.dr_nopwrite) {
1873                         blkptr_t *bp = zio->io_bp;
1874                         blkptr_t *bp_orig = &zio->io_bp_orig;
1875                         uint8_t chksum = BP_GET_CHECKSUM(bp_orig);
1876 
1877                         ASSERT(BP_EQUAL(bp, bp_orig));
1878                         VERIFY(BP_EQUAL(bp, db->db_blkptr));
1879                         ASSERT(zio->io_prop.zp_compress != ZIO_COMPRESS_OFF);
1880                         ASSERT(zio_checksum_table[chksum].ci_flags &
1881                             ZCHECKSUM_FLAG_NOPWRITE);
1882                 }
1883                 dr->dt.dl.dr_overridden_by = *zio->io_bp;
1884                 dr->dt.dl.dr_override_state = DR_OVERRIDDEN;
1885                 dr->dt.dl.dr_copies = zio->io_prop.zp_copies;
1886 
1887                 /*
1888                  * Old style holes are filled with all zeros, whereas
1889                  * new-style holes maintain their lsize, type, level,
1890                  * and birth time (see zio_write_compress). While we
1891                  * need to reset the BP_SET_LSIZE() call that happened
1892                  * in dmu_sync_ready for old style holes, we do *not*
1893                  * want to wipe out the information contained in new
1894                  * style holes. Thus, only zero out the block pointer if
1895                  * it's an old style hole.
1896                  */
1897                 if (BP_IS_HOLE(&dr->dt.dl.dr_overridden_by) &&
1898                     dr->dt.dl.dr_overridden_by.blk_birth == 0)
1899                         BP_ZERO(&dr->dt.dl.dr_overridden_by);
1900         } else {
1901                 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
1902         }
1903         cv_broadcast(&db->db_changed);
1904         mutex_exit(&db->db_mtx);
1905 
1906         dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
1907 
1908         kmem_free(dsa, sizeof (*dsa));
1909 }
1910 
1911 static void
1912 dmu_sync_late_arrival_done(zio_t *zio)
1913 {
1914         blkptr_t *bp = zio->io_bp;
1915         dmu_sync_arg_t *dsa = zio->io_private;
1916         blkptr_t *bp_orig = &zio->io_bp_orig;
1917         zgd_t *zgd = dsa->dsa_zgd;
1918 
1919         if (zio->io_error == 0) {
1920                 /*
1921                  * Record the vdev(s) backing this blkptr so they can be
1922                  * flushed after the writes for the lwb have completed.
1923                  */
1924                 zil_lwb_add_block(zgd->zgd_lwb, zgd->zgd_bp);
1925 
1926                 if (!BP_IS_HOLE(bp)) {
1927                         ASSERT(!(zio->io_flags & ZIO_FLAG_NOPWRITE));
1928                         ASSERT(BP_IS_HOLE(bp_orig) || !BP_EQUAL(bp, bp_orig));
1929                         ASSERT(zio->io_bp->blk_birth == zio->io_txg);
1930                         ASSERT(zio->io_txg > spa_syncing_txg(zio->io_spa));
1931                         zio_free(zio->io_spa, zio->io_txg, zio->io_bp);
1932                 }
1933         }
1934 
1935         dmu_tx_commit(dsa->dsa_tx);
1936 
1937         dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
1938 
1939         abd_put(zio->io_abd);
1940         kmem_free(dsa, sizeof (*dsa));
1941 }
1942 
1943 static int
1944 dmu_sync_late_arrival(zio_t *pio, objset_t *os, dmu_sync_cb_t *done, zgd_t *zgd,
1945     zio_prop_t *zp, zbookmark_phys_t *zb)
1946 {
1947         dmu_sync_arg_t *dsa;
1948         dmu_tx_t *tx;
1949 
1950         tx = dmu_tx_create(os);
1951         dmu_tx_hold_space(tx, zgd->zgd_db->db_size);
1952         if (dmu_tx_assign(tx, TXG_WAIT) != 0) {
1953                 dmu_tx_abort(tx);
1954                 /* Make zl_get_data do txg_waited_synced() */
1955                 return (SET_ERROR(EIO));
1956         }
1957 
1958         /*
1959          * In order to prevent the zgd's lwb from being free'd prior to
1960          * dmu_sync_late_arrival_done() being called, we have to ensure
1961          * the lwb's "max txg" takes this tx's txg into account.
1962          */
1963         zil_lwb_add_txg(zgd->zgd_lwb, dmu_tx_get_txg(tx));
1964 
1965         dsa = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
1966         dsa->dsa_dr = NULL;
1967         dsa->dsa_done = done;
1968         dsa->dsa_zgd = zgd;
1969         dsa->dsa_tx = tx;
1970 
1971         /*
1972          * Since we are currently syncing this txg, it's nontrivial to
1973          * determine what BP to nopwrite against, so we disable nopwrite.
1974          *
1975          * When syncing, the db_blkptr is initially the BP of the previous
1976          * txg.  We can not nopwrite against it because it will be changed
1977          * (this is similar to the non-late-arrival case where the dbuf is
1978          * dirty in a future txg).
1979          *
1980          * Then dbuf_write_ready() sets bp_blkptr to the location we will write.
1981          * We can not nopwrite against it because although the BP will not
1982          * (typically) be changed, the data has not yet been persisted to this
1983          * location.
1984          *
1985          * Finally, when dbuf_write_done() is called, it is theoretically
1986          * possible to always nopwrite, because the data that was written in
1987          * this txg is the same data that we are trying to write.  However we
1988          * would need to check that this dbuf is not dirty in any future
1989          * txg's (as we do in the normal dmu_sync() path). For simplicity, we
1990          * don't nopwrite in this case.
1991          */
1992         zp->zp_nopwrite = B_FALSE;
1993 
1994         zio_nowait(zio_write(pio, os->os_spa, dmu_tx_get_txg(tx), zgd->zgd_bp,
1995             abd_get_from_buf(zgd->zgd_db->db_data, zgd->zgd_db->db_size),
1996             zgd->zgd_db->db_size, zgd->zgd_db->db_size, zp,
1997             dmu_sync_late_arrival_ready, NULL, NULL, dmu_sync_late_arrival_done,
1998             dsa, ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_CANFAIL, zb));
1999 
2000         return (0);
2001 }
2002 
2003 /*
2004  * Intent log support: sync the block associated with db to disk.
2005  * N.B. and XXX: the caller is responsible for making sure that the
2006  * data isn't changing while dmu_sync() is writing it.
2007  *
2008  * Return values:
2009  *
2010  *      EEXIST: this txg has already been synced, so there's nothing to do.
2011  *              The caller should not log the write.
2012  *
2013  *      ENOENT: the block was dbuf_free_range()'d, so there's nothing to do.
2014  *              The caller should not log the write.
2015  *
2016  *      EALREADY: this block is already in the process of being synced.
2017  *              The caller should track its progress (somehow).
2018  *
2019  *      EIO: could not do the I/O.
2020  *              The caller should do a txg_wait_synced().
2021  *
2022  *      0: the I/O has been initiated.
2023  *              The caller should log this blkptr in the done callback.
2024  *              It is possible that the I/O will fail, in which case
2025  *              the error will be reported to the done callback and
2026  *              propagated to pio from zio_done().
2027  */
2028 int
2029 dmu_sync(zio_t *pio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd)
2030 {
2031         dmu_buf_impl_t *db = (dmu_buf_impl_t *)zgd->zgd_db;
2032         objset_t *os = db->db_objset;
2033         dsl_dataset_t *ds = os->os_dsl_dataset;
2034         dbuf_dirty_record_t *dr;
2035         dmu_sync_arg_t *dsa;
2036         zbookmark_phys_t zb;
2037         zio_prop_t zp;
2038         dnode_t *dn;
2039 
2040         ASSERT(pio != NULL);
2041         ASSERT(txg != 0);
2042 
2043         SET_BOOKMARK(&zb, ds->ds_object,
2044             db->db.db_object, db->db_level, db->db_blkid);
2045 
2046         DB_DNODE_ENTER(db);
2047         dn = DB_DNODE(db);
2048         dmu_write_policy(os, dn, db->db_level, WP_DMU_SYNC, &zp);
2049         DB_DNODE_EXIT(db);
2050 
2051         /*
2052          * If we're frozen (running ziltest), we always need to generate a bp.
2053          */
2054         if (txg > spa_freeze_txg(os->os_spa))
2055                 return (dmu_sync_late_arrival(pio, os, done, zgd, &zp, &zb));
2056 
2057         /*
2058          * Grabbing db_mtx now provides a barrier between dbuf_sync_leaf()
2059          * and us.  If we determine that this txg is not yet syncing,
2060          * but it begins to sync a moment later, that's OK because the
2061          * sync thread will block in dbuf_sync_leaf() until we drop db_mtx.
2062          */
2063         mutex_enter(&db->db_mtx);
2064 
2065         if (txg <= spa_last_synced_txg(os->os_spa)) {
2066                 /*
2067                  * This txg has already synced.  There's nothing to do.
2068                  */
2069                 mutex_exit(&db->db_mtx);
2070                 return (SET_ERROR(EEXIST));
2071         }
2072 
2073         if (txg <= spa_syncing_txg(os->os_spa)) {
2074                 /*
2075                  * This txg is currently syncing, so we can't mess with
2076                  * the dirty record anymore; just write a new log block.
2077                  */
2078                 mutex_exit(&db->db_mtx);
2079                 return (dmu_sync_late_arrival(pio, os, done, zgd, &zp, &zb));
2080         }
2081 
2082         dr = db->db_last_dirty;
2083         while (dr && dr->dr_txg != txg)
2084                 dr = dr->dr_next;
2085 
2086         if (dr == NULL) {
2087                 /*
2088                  * There's no dr for this dbuf, so it must have been freed.
2089                  * There's no need to log writes to freed blocks, so we're done.
2090                  */
2091                 mutex_exit(&db->db_mtx);
2092                 return (SET_ERROR(ENOENT));
2093         }
2094 
2095         ASSERT(dr->dr_next == NULL || dr->dr_next->dr_txg < txg);
2096 
2097         if (db->db_blkptr != NULL) {
2098                 /*
2099                  * We need to fill in zgd_bp with the current blkptr so that
2100                  * the nopwrite code can check if we're writing the same
2101                  * data that's already on disk.  We can only nopwrite if we
2102                  * are sure that after making the copy, db_blkptr will not
2103                  * change until our i/o completes.  We ensure this by
2104                  * holding the db_mtx, and only allowing nopwrite if the
2105                  * block is not already dirty (see below).  This is verified
2106                  * by dmu_sync_done(), which VERIFYs that the db_blkptr has
2107                  * not changed.
2108                  */
2109                 *zgd->zgd_bp = *db->db_blkptr;
2110         }
2111 
2112         /*
2113          * Assume the on-disk data is X, the current syncing data (in
2114          * txg - 1) is Y, and the current in-memory data is Z (currently
2115          * in dmu_sync).
2116          *
2117          * We usually want to perform a nopwrite if X and Z are the
2118          * same.  However, if Y is different (i.e. the BP is going to
2119          * change before this write takes effect), then a nopwrite will
2120          * be incorrect - we would override with X, which could have
2121          * been freed when Y was written.
2122          *
2123          * (Note that this is not a concern when we are nop-writing from
2124          * syncing context, because X and Y must be identical, because
2125          * all previous txgs have been synced.)
2126          *
2127          * Therefore, we disable nopwrite if the current BP could change
2128          * before this TXG.  There are two ways it could change: by
2129          * being dirty (dr_next is non-NULL), or by being freed
2130          * (dnode_block_freed()).  This behavior is verified by
2131          * zio_done(), which VERIFYs that the override BP is identical
2132          * to the on-disk BP.
2133          */
2134         DB_DNODE_ENTER(db);
2135         dn = DB_DNODE(db);
2136         if (dr->dr_next != NULL || dnode_block_freed(dn, db->db_blkid))
2137                 zp.zp_nopwrite = B_FALSE;
2138         DB_DNODE_EXIT(db);
2139 
2140         ASSERT(dr->dr_txg == txg);
2141         if (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC ||
2142             dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
2143                 /*
2144                  * We have already issued a sync write for this buffer,
2145                  * or this buffer has already been synced.  It could not
2146                  * have been dirtied since, or we would have cleared the state.
2147                  */
2148                 mutex_exit(&db->db_mtx);
2149                 return (SET_ERROR(EALREADY));
2150         }
2151 
2152         ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
2153         dr->dt.dl.dr_override_state = DR_IN_DMU_SYNC;
2154         mutex_exit(&db->db_mtx);
2155 
2156         dsa = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
2157         dsa->dsa_dr = dr;
2158         dsa->dsa_done = done;
2159         dsa->dsa_zgd = zgd;
2160         dsa->dsa_tx = NULL;
2161 
2162         zio_nowait(arc_write(pio, os->os_spa, txg,
2163             zgd->zgd_bp, dr->dt.dl.dr_data, DBUF_IS_L2CACHEABLE(db),
2164             &zp, dmu_sync_ready, NULL, NULL, dmu_sync_done, dsa,
2165             ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_CANFAIL, &zb));
2166 
2167         return (0);
2168 }
2169 
2170 int
2171 dmu_object_set_nlevels(objset_t *os, uint64_t object, int nlevels, dmu_tx_t *tx)
2172 {
2173         dnode_t *dn;
2174         int err;
2175 
2176         err = dnode_hold(os, object, FTAG, &dn);
2177         if (err)
2178                 return (err);
2179         err = dnode_set_nlevels(dn, nlevels, tx);
2180         dnode_rele(dn, FTAG);
2181         return (err);
2182 }
2183 
2184 int
2185 dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size, int ibs,
2186     dmu_tx_t *tx)
2187 {
2188         dnode_t *dn;
2189         int err;
2190 
2191         err = dnode_hold(os, object, FTAG, &dn);
2192         if (err)
2193                 return (err);
2194         err = dnode_set_blksz(dn, size, ibs, tx);
2195         dnode_rele(dn, FTAG);
2196         return (err);
2197 }
2198 
2199 int
2200 dmu_object_set_maxblkid(objset_t *os, uint64_t object, uint64_t maxblkid,
2201     dmu_tx_t *tx)
2202 {
2203         dnode_t *dn;
2204         int err;
2205 
2206         err = dnode_hold(os, object, FTAG, &dn);
2207         if (err)
2208                 return (err);
2209         rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
2210         dnode_new_blkid(dn, maxblkid, tx, B_FALSE, B_TRUE);
2211         rw_exit(&dn->dn_struct_rwlock);
2212         dnode_rele(dn, FTAG);
2213         return (0);
2214 }
2215 
2216 void
2217 dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
2218     dmu_tx_t *tx)
2219 {
2220         dnode_t *dn;
2221 
2222         /*
2223          * Send streams include each object's checksum function.  This
2224          * check ensures that the receiving system can understand the
2225          * checksum function transmitted.
2226          */
2227         ASSERT3U(checksum, <, ZIO_CHECKSUM_LEGACY_FUNCTIONS);
2228 
2229         VERIFY0(dnode_hold(os, object, FTAG, &dn));
2230         ASSERT3U(checksum, <, ZIO_CHECKSUM_FUNCTIONS);
2231         dn->dn_checksum = checksum;
2232         dnode_setdirty(dn, tx);
2233         dnode_rele(dn, FTAG);
2234 }
2235 
2236 void
2237 dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
2238     dmu_tx_t *tx)
2239 {
2240         dnode_t *dn;
2241 
2242         /*
2243          * Send streams include each object's compression function.  This
2244          * check ensures that the receiving system can understand the
2245          * compression function transmitted.
2246          */
2247         ASSERT3U(compress, <, ZIO_COMPRESS_LEGACY_FUNCTIONS);
2248 
2249         VERIFY0(dnode_hold(os, object, FTAG, &dn));
2250         dn->dn_compress = compress;
2251         dnode_setdirty(dn, tx);
2252         dnode_rele(dn, FTAG);
2253 }
2254 
2255 /*
2256  * When the "redundant_metadata" property is set to "most", only indirect
2257  * blocks of this level and higher will have an additional ditto block.
2258  */
2259 int zfs_redundant_metadata_most_ditto_level = 2;
2260 
2261 void
2262 dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp, zio_prop_t *zp)
2263 {
2264         dmu_object_type_t type = dn ? dn->dn_type : DMU_OT_OBJSET;
2265         boolean_t ismd = (level > 0 || DMU_OT_IS_METADATA(type) ||
2266             (wp & WP_SPILL));
2267         enum zio_checksum checksum = os->os_checksum;
2268         enum zio_compress compress = os->os_compress;
2269         enum zio_checksum dedup_checksum = os->os_dedup_checksum;
2270         boolean_t dedup = B_FALSE;
2271         boolean_t nopwrite = B_FALSE;
2272         boolean_t dedup_verify = os->os_dedup_verify;
2273         boolean_t encrypt = B_FALSE;
2274         int copies = os->os_copies;
2275 
2276         /*
2277          * We maintain different write policies for each of the following
2278          * types of data:
2279          *       1. metadata
2280          *       2. preallocated blocks (i.e. level-0 blocks of a dump device)
2281          *       3. all other level 0 blocks
2282          */
2283         if (ismd) {
2284                 /*
2285                  * XXX -- we should design a compression algorithm
2286                  * that specializes in arrays of bps.
2287                  */
2288                 compress = zio_compress_select(os->os_spa,
2289                     ZIO_COMPRESS_ON, ZIO_COMPRESS_ON);
2290 
2291                 /*
2292                  * Metadata always gets checksummed.  If the data
2293                  * checksum is multi-bit correctable, and it's not a
2294                  * ZBT-style checksum, then it's suitable for metadata
2295                  * as well.  Otherwise, the metadata checksum defaults
2296                  * to fletcher4.
2297                  */
2298                 if (!(zio_checksum_table[checksum].ci_flags &
2299                     ZCHECKSUM_FLAG_METADATA) ||
2300                     (zio_checksum_table[checksum].ci_flags &
2301                     ZCHECKSUM_FLAG_EMBEDDED))
2302                         checksum = ZIO_CHECKSUM_FLETCHER_4;
2303 
2304                 if (os->os_redundant_metadata == ZFS_REDUNDANT_METADATA_ALL ||
2305                     (os->os_redundant_metadata ==
2306                     ZFS_REDUNDANT_METADATA_MOST &&
2307                     (level >= zfs_redundant_metadata_most_ditto_level ||
2308                     DMU_OT_IS_METADATA(type) || (wp & WP_SPILL))))
2309                         copies++;
2310         } else if (wp & WP_NOFILL) {
2311                 ASSERT(level == 0);
2312 
2313                 /*
2314                  * If we're writing preallocated blocks, we aren't actually
2315                  * writing them so don't set any policy properties.  These
2316                  * blocks are currently only used by an external subsystem
2317                  * outside of zfs (i.e. dump) and not written by the zio
2318                  * pipeline.
2319                  */
2320                 compress = ZIO_COMPRESS_OFF;
2321                 checksum = ZIO_CHECKSUM_NOPARITY;
2322         } else {
2323                 compress = zio_compress_select(os->os_spa, dn->dn_compress,
2324                     compress);
2325 
2326                 checksum = (dedup_checksum == ZIO_CHECKSUM_OFF) ?
2327                     zio_checksum_select(dn->dn_checksum, checksum) :
2328                     dedup_checksum;
2329 
2330                 /*
2331                  * Determine dedup setting.  If we are in dmu_sync(),
2332                  * we won't actually dedup now because that's all
2333                  * done in syncing context; but we do want to use the
2334                  * dedup checkum.  If the checksum is not strong
2335                  * enough to ensure unique signatures, force
2336                  * dedup_verify.
2337                  */
2338                 if (dedup_checksum != ZIO_CHECKSUM_OFF) {
2339                         dedup = (wp & WP_DMU_SYNC) ? B_FALSE : B_TRUE;
2340                         if (!(zio_checksum_table[checksum].ci_flags &
2341                             ZCHECKSUM_FLAG_DEDUP))
2342                                 dedup_verify = B_TRUE;
2343                 }
2344 
2345                 /*
2346                  * Enable nopwrite if we have secure enough checksum
2347                  * algorithm (see comment in zio_nop_write) and
2348                  * compression is enabled.  We don't enable nopwrite if
2349                  * dedup is enabled as the two features are mutually
2350                  * exclusive.
2351                  */
2352                 nopwrite = (!dedup && (zio_checksum_table[checksum].ci_flags &
2353                     ZCHECKSUM_FLAG_NOPWRITE) &&
2354                     compress != ZIO_COMPRESS_OFF && zfs_nopwrite_enabled);
2355         }
2356 
2357         /*
2358          * All objects in an encrypted objset are protected from modification
2359          * via a MAC. Encrypted objects store their IV and salt in the last DVA
2360          * in the bp, so we cannot use all copies. Encrypted objects are also
2361          * not subject to nopwrite since writing the same data will still
2362          * result in a new ciphertext. Only encrypted blocks can be dedup'd
2363          * to avoid ambiguity in the dedup code since the DDT does not store
2364          * object types.
2365          */
2366         if (os->os_encrypted && (wp & WP_NOFILL) == 0) {
2367                 encrypt = B_TRUE;
2368 
2369                 if (DMU_OT_IS_ENCRYPTED(type)) {
2370                         copies = MIN(copies, SPA_DVAS_PER_BP - 1);
2371                         nopwrite = B_FALSE;
2372                 } else {
2373                         dedup = B_FALSE;
2374                 }
2375 
2376                 if (level <= 0 &&
2377                     (type == DMU_OT_DNODE || type == DMU_OT_OBJSET)) {
2378                         compress = ZIO_COMPRESS_EMPTY;
2379                 }
2380         }
2381 
2382         zp->zp_compress = compress;
2383         zp->zp_checksum = checksum;
2384         zp->zp_type = (wp & WP_SPILL) ? dn->dn_bonustype : type;
2385         zp->zp_level = level;
2386         zp->zp_copies = MIN(copies, spa_max_replication(os->os_spa));
2387         zp->zp_dedup = dedup;
2388         zp->zp_dedup_verify = dedup && dedup_verify;
2389         zp->zp_nopwrite = nopwrite;
2390         zp->zp_zpl_smallblk = DMU_OT_IS_FILE(zp->zp_type) ?
2391             os->os_zpl_special_smallblock : 0;
2392         zp->zp_encrypt = encrypt;
2393         zp->zp_byteorder = ZFS_HOST_BYTEORDER;
2394         bzero(zp->zp_salt, ZIO_DATA_SALT_LEN);
2395         bzero(zp->zp_iv, ZIO_DATA_IV_LEN);
2396         bzero(zp->zp_mac, ZIO_DATA_MAC_LEN);
2397 }
2398 
2399 int
2400 dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole, uint64_t *off)
2401 {
2402         dnode_t *dn;
2403         int err;
2404 
2405         /*
2406          * Sync any current changes before
2407          * we go trundling through the block pointers.
2408          */
2409         err = dmu_object_wait_synced(os, object);
2410         if (err) {
2411                 return (err);
2412         }
2413 
2414         err = dnode_hold(os, object, FTAG, &dn);
2415         if (err) {
2416                 return (err);
2417         }
2418 
2419         err = dnode_next_offset(dn, (hole ? DNODE_FIND_HOLE : 0), off, 1, 1, 0);
2420         dnode_rele(dn, FTAG);
2421 
2422         return (err);
2423 }
2424 
2425 /*
2426  * Given the ZFS object, if it contains any dirty nodes
2427  * this function flushes all dirty blocks to disk. This
2428  * ensures the DMU object info is updated. A more efficient
2429  * future version might just find the TXG with the maximum
2430  * ID and wait for that to be synced.
2431  */
2432 int
2433 dmu_object_wait_synced(objset_t *os, uint64_t object)
2434 {
2435         dnode_t *dn;
2436         int error, i;
2437 
2438         error = dnode_hold(os, object, FTAG, &dn);
2439         if (error) {
2440                 return (error);
2441         }
2442 
2443         for (i = 0; i < TXG_SIZE; i++) {
2444                 if (list_link_active(&dn->dn_dirty_link[i])) {
2445                         break;
2446                 }
2447         }
2448         dnode_rele(dn, FTAG);
2449         if (i != TXG_SIZE) {
2450                 txg_wait_synced(dmu_objset_pool(os), 0);
2451         }
2452 
2453         return (0);
2454 }
2455 
2456 void
2457 dmu_object_info_from_dnode(dnode_t *dn, dmu_object_info_t *doi)
2458 {
2459         dnode_phys_t *dnp;
2460 
2461         rw_enter(&dn->dn_struct_rwlock, RW_READER);
2462         mutex_enter(&dn->dn_mtx);
2463 
2464         dnp = dn->dn_phys;
2465 
2466         doi->doi_data_block_size = dn->dn_datablksz;
2467         doi->doi_metadata_block_size = dn->dn_indblkshift ?
2468             1ULL << dn->dn_indblkshift : 0;
2469         doi->doi_type = dn->dn_type;
2470         doi->doi_bonus_type = dn->dn_bonustype;
2471         doi->doi_bonus_size = dn->dn_bonuslen;
2472         doi->doi_dnodesize = dn->dn_num_slots << DNODE_SHIFT;
2473         doi->doi_indirection = dn->dn_nlevels;
2474         doi->doi_checksum = dn->dn_checksum;
2475         doi->doi_compress = dn->dn_compress;
2476         doi->doi_nblkptr = dn->dn_nblkptr;
2477         doi->doi_physical_blocks_512 = (DN_USED_BYTES(dnp) + 256) >> 9;
2478         doi->doi_max_offset = (dn->dn_maxblkid + 1) * dn->dn_datablksz;
2479         doi->doi_fill_count = 0;
2480         for (int i = 0; i < dnp->dn_nblkptr; i++)
2481                 doi->doi_fill_count += BP_GET_FILL(&dnp->dn_blkptr[i]);
2482 
2483         mutex_exit(&dn->dn_mtx);
2484         rw_exit(&dn->dn_struct_rwlock);
2485 }
2486 
2487 /*
2488  * Get information on a DMU object.
2489  * If doi is NULL, just indicates whether the object exists.
2490  */
2491 int
2492 dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi)
2493 {
2494         dnode_t *dn;
2495         int err = dnode_hold(os, object, FTAG, &dn);
2496 
2497         if (err)
2498                 return (err);
2499 
2500         if (doi != NULL)
2501                 dmu_object_info_from_dnode(dn, doi);
2502 
2503         dnode_rele(dn, FTAG);
2504         return (0);
2505 }
2506 
2507 /*
2508  * As above, but faster; can be used when you have a held dbuf in hand.
2509  */
2510 void
2511 dmu_object_info_from_db(dmu_buf_t *db_fake, dmu_object_info_t *doi)
2512 {
2513         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2514 
2515         DB_DNODE_ENTER(db);
2516         dmu_object_info_from_dnode(DB_DNODE(db), doi);
2517         DB_DNODE_EXIT(db);
2518 }
2519 
2520 /*
2521  * Faster still when you only care about the size.
2522  * This is specifically optimized for zfs_getattr().
2523  */
2524 void
2525 dmu_object_size_from_db(dmu_buf_t *db_fake, uint32_t *blksize,
2526     u_longlong_t *nblk512)
2527 {
2528         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2529         dnode_t *dn;
2530 
2531         DB_DNODE_ENTER(db);
2532         dn = DB_DNODE(db);
2533 
2534         *blksize = dn->dn_datablksz;
2535         /* add in number of slots used for the dnode itself */
2536         *nblk512 = ((DN_USED_BYTES(dn->dn_phys) + SPA_MINBLOCKSIZE/2) >>
2537             SPA_MINBLOCKSHIFT) + dn->dn_num_slots;
2538         DB_DNODE_EXIT(db);
2539 }
2540 
2541 void
2542 dmu_object_dnsize_from_db(dmu_buf_t *db_fake, int *dnsize)
2543 {
2544         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
2545         dnode_t *dn;
2546 
2547         DB_DNODE_ENTER(db);
2548         dn = DB_DNODE(db);
2549         *dnsize = dn->dn_num_slots << DNODE_SHIFT;
2550         DB_DNODE_EXIT(db);
2551 }
2552 
2553 void
2554 byteswap_uint64_array(void *vbuf, size_t size)
2555 {
2556         uint64_t *buf = vbuf;
2557         size_t count = size >> 3;
2558         int i;
2559 
2560         ASSERT((size & 7) == 0);
2561 
2562         for (i = 0; i < count; i++)
2563                 buf[i] = BSWAP_64(buf[i]);
2564 }
2565 
2566 void
2567 byteswap_uint32_array(void *vbuf, size_t size)
2568 {
2569         uint32_t *buf = vbuf;
2570         size_t count = size >> 2;
2571         int i;
2572 
2573         ASSERT((size & 3) == 0);
2574 
2575         for (i = 0; i < count; i++)
2576                 buf[i] = BSWAP_32(buf[i]);
2577 }
2578 
2579 void
2580 byteswap_uint16_array(void *vbuf, size_t size)
2581 {
2582         uint16_t *buf = vbuf;
2583         size_t count = size >> 1;
2584         int i;
2585 
2586         ASSERT((size & 1) == 0);
2587 
2588         for (i = 0; i < count; i++)
2589                 buf[i] = BSWAP_16(buf[i]);
2590 }
2591 
2592 /* ARGSUSED */
2593 void
2594 byteswap_uint8_array(void *vbuf, size_t size)
2595 {
2596 }
2597 
2598 void
2599 dmu_init(void)
2600 {
2601         abd_init();
2602         zfs_dbgmsg_init();
2603         sa_cache_init();
2604         xuio_stat_init();
2605         dmu_objset_init();
2606         dnode_init();
2607         zfetch_init();
2608         l2arc_init();
2609         arc_init();
2610         dbuf_init();
2611 }
2612 
2613 void
2614 dmu_fini(void)
2615 {
2616         arc_fini(); /* arc depends on l2arc, so arc must go first */
2617         l2arc_fini();
2618         zfetch_fini();
2619         dbuf_fini();
2620         dnode_fini();
2621         dmu_objset_fini();
2622         xuio_stat_fini();
2623         sa_cache_fini();
2624         zfs_dbgmsg_fini();
2625         abd_fini();
2626 }