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  * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
  24  */
  25 /* Copyright (c) 2013 by Saso Kiselkov. All rights reserved. */
  26 /* Copyright (c) 2013, Joyent, Inc. All rights reserved. */
  27 
  28 #include <sys/dmu.h>
  29 #include <sys/dmu_impl.h>
  30 #include <sys/dmu_tx.h>
  31 #include <sys/dbuf.h>
  32 #include <sys/dnode.h>
  33 #include <sys/zfs_context.h>
  34 #include <sys/dmu_objset.h>
  35 #include <sys/dmu_traverse.h>
  36 #include <sys/dsl_dataset.h>
  37 #include <sys/dsl_dir.h>
  38 #include <sys/dsl_pool.h>
  39 #include <sys/dsl_synctask.h>
  40 #include <sys/dsl_prop.h>
  41 #include <sys/dmu_zfetch.h>
  42 #include <sys/zfs_ioctl.h>
  43 #include <sys/zap.h>
  44 #include <sys/zio_checksum.h>
  45 #include <sys/zio_compress.h>
  46 #include <sys/sa.h>
  47 #ifdef _KERNEL
  48 #include <sys/vmsystm.h>
  49 #include <sys/zfs_znode.h>
  50 #endif
  51 
  52 /*
  53  * Enable/disable nopwrite feature.
  54  */
  55 int zfs_nopwrite_enabled = 1;
  56 
  57 const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES] = {
  58         {       DMU_BSWAP_UINT8,        TRUE,   "unallocated"           },
  59         {       DMU_BSWAP_ZAP,          TRUE,   "object directory"      },
  60         {       DMU_BSWAP_UINT64,       TRUE,   "object array"          },
  61         {       DMU_BSWAP_UINT8,        TRUE,   "packed nvlist"         },
  62         {       DMU_BSWAP_UINT64,       TRUE,   "packed nvlist size"    },
  63         {       DMU_BSWAP_UINT64,       TRUE,   "bpobj"                 },
  64         {       DMU_BSWAP_UINT64,       TRUE,   "bpobj header"          },
  65         {       DMU_BSWAP_UINT64,       TRUE,   "SPA space map header"  },
  66         {       DMU_BSWAP_UINT64,       TRUE,   "SPA space map"         },
  67         {       DMU_BSWAP_UINT64,       TRUE,   "ZIL intent log"        },
  68         {       DMU_BSWAP_DNODE,        TRUE,   "DMU dnode"             },
  69         {       DMU_BSWAP_OBJSET,       TRUE,   "DMU objset"            },
  70         {       DMU_BSWAP_UINT64,       TRUE,   "DSL directory"         },
  71         {       DMU_BSWAP_ZAP,          TRUE,   "DSL directory child map"},
  72         {       DMU_BSWAP_ZAP,          TRUE,   "DSL dataset snap map"  },
  73         {       DMU_BSWAP_ZAP,          TRUE,   "DSL props"             },
  74         {       DMU_BSWAP_UINT64,       TRUE,   "DSL dataset"           },
  75         {       DMU_BSWAP_ZNODE,        TRUE,   "ZFS znode"             },
  76         {       DMU_BSWAP_OLDACL,       TRUE,   "ZFS V0 ACL"            },
  77         {       DMU_BSWAP_UINT8,        FALSE,  "ZFS plain file"        },
  78         {       DMU_BSWAP_ZAP,          TRUE,   "ZFS directory"         },
  79         {       DMU_BSWAP_ZAP,          TRUE,   "ZFS master node"       },
  80         {       DMU_BSWAP_ZAP,          TRUE,   "ZFS delete queue"      },
  81         {       DMU_BSWAP_UINT8,        FALSE,  "zvol object"           },
  82         {       DMU_BSWAP_ZAP,          TRUE,   "zvol prop"             },
  83         {       DMU_BSWAP_UINT8,        FALSE,  "other uint8[]"         },
  84         {       DMU_BSWAP_UINT64,       FALSE,  "other uint64[]"        },
  85         {       DMU_BSWAP_ZAP,          TRUE,   "other ZAP"             },
  86         {       DMU_BSWAP_ZAP,          TRUE,   "persistent error log"  },
  87         {       DMU_BSWAP_UINT8,        TRUE,   "SPA history"           },
  88         {       DMU_BSWAP_UINT64,       TRUE,   "SPA history offsets"   },
  89         {       DMU_BSWAP_ZAP,          TRUE,   "Pool properties"       },
  90         {       DMU_BSWAP_ZAP,          TRUE,   "DSL permissions"       },
  91         {       DMU_BSWAP_ACL,          TRUE,   "ZFS ACL"               },
  92         {       DMU_BSWAP_UINT8,        TRUE,   "ZFS SYSACL"            },
  93         {       DMU_BSWAP_UINT8,        TRUE,   "FUID table"            },
  94         {       DMU_BSWAP_UINT64,       TRUE,   "FUID table size"       },
  95         {       DMU_BSWAP_ZAP,          TRUE,   "DSL dataset next clones"},
  96         {       DMU_BSWAP_ZAP,          TRUE,   "scan work queue"       },
  97         {       DMU_BSWAP_ZAP,          TRUE,   "ZFS user/group used"   },
  98         {       DMU_BSWAP_ZAP,          TRUE,   "ZFS user/group quota"  },
  99         {       DMU_BSWAP_ZAP,          TRUE,   "snapshot refcount tags"},
 100         {       DMU_BSWAP_ZAP,          TRUE,   "DDT ZAP algorithm"     },
 101         {       DMU_BSWAP_ZAP,          TRUE,   "DDT statistics"        },
 102         {       DMU_BSWAP_UINT8,        TRUE,   "System attributes"     },
 103         {       DMU_BSWAP_ZAP,          TRUE,   "SA master node"        },
 104         {       DMU_BSWAP_ZAP,          TRUE,   "SA attr registration"  },
 105         {       DMU_BSWAP_ZAP,          TRUE,   "SA attr layouts"       },
 106         {       DMU_BSWAP_ZAP,          TRUE,   "scan translations"     },
 107         {       DMU_BSWAP_UINT8,        FALSE,  "deduplicated block"    },
 108         {       DMU_BSWAP_ZAP,          TRUE,   "DSL deadlist map"      },
 109         {       DMU_BSWAP_UINT64,       TRUE,   "DSL deadlist map hdr"  },
 110         {       DMU_BSWAP_ZAP,          TRUE,   "DSL dir clones"        },
 111         {       DMU_BSWAP_UINT64,       TRUE,   "bpobj subobj"          }
 112 };
 113 
 114 const dmu_object_byteswap_info_t dmu_ot_byteswap[DMU_BSWAP_NUMFUNCS] = {
 115         {       byteswap_uint8_array,   "uint8"         },
 116         {       byteswap_uint16_array,  "uint16"        },
 117         {       byteswap_uint32_array,  "uint32"        },
 118         {       byteswap_uint64_array,  "uint64"        },
 119         {       zap_byteswap,           "zap"           },
 120         {       dnode_buf_byteswap,     "dnode"         },
 121         {       dmu_objset_byteswap,    "objset"        },
 122         {       zfs_znode_byteswap,     "znode"         },
 123         {       zfs_oldacl_byteswap,    "oldacl"        },
 124         {       zfs_acl_byteswap,       "acl"           }
 125 };
 126 
 127 int
 128 dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
 129     void *tag, dmu_buf_t **dbp, int flags)
 130 {
 131         dnode_t *dn;
 132         uint64_t blkid;
 133         dmu_buf_impl_t *db;
 134         int err;
 135         int db_flags = DB_RF_CANFAIL;
 136 
 137         if (flags & DMU_READ_NO_PREFETCH)
 138                 db_flags |= DB_RF_NOPREFETCH;
 139 
 140         err = dnode_hold(os, object, FTAG, &dn);
 141         if (err)
 142                 return (err);
 143         blkid = dbuf_whichblock(dn, offset);
 144         rw_enter(&dn->dn_struct_rwlock, RW_READER);
 145         db = dbuf_hold(dn, blkid, tag);
 146         rw_exit(&dn->dn_struct_rwlock);
 147         if (db == NULL) {
 148                 err = SET_ERROR(EIO);
 149         } else {
 150                 err = dbuf_read(db, NULL, db_flags);
 151                 if (err) {
 152                         dbuf_rele(db, tag);
 153                         db = NULL;
 154                 }
 155         }
 156 
 157         dnode_rele(dn, FTAG);
 158         *dbp = &db->db; /* NULL db plus first field offset is NULL */
 159         return (err);
 160 }
 161 
 162 int
 163 dmu_bonus_max(void)
 164 {
 165         return (DN_MAX_BONUSLEN);
 166 }
 167 
 168 int
 169 dmu_set_bonus(dmu_buf_t *db_fake, int newsize, dmu_tx_t *tx)
 170 {
 171         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
 172         dnode_t *dn;
 173         int error;
 174 
 175         DB_DNODE_ENTER(db);
 176         dn = DB_DNODE(db);
 177 
 178         if (dn->dn_bonus != db) {
 179                 error = SET_ERROR(EINVAL);
 180         } else if (newsize < 0 || newsize > db_fake->db_size) {
 181                 error = SET_ERROR(EINVAL);
 182         } else {
 183                 dnode_setbonuslen(dn, newsize, tx);
 184                 error = 0;
 185         }
 186 
 187         DB_DNODE_EXIT(db);
 188         return (error);
 189 }
 190 
 191 int
 192 dmu_set_bonustype(dmu_buf_t *db_fake, dmu_object_type_t type, dmu_tx_t *tx)
 193 {
 194         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
 195         dnode_t *dn;
 196         int error;
 197 
 198         DB_DNODE_ENTER(db);
 199         dn = DB_DNODE(db);
 200 
 201         if (!DMU_OT_IS_VALID(type)) {
 202                 error = SET_ERROR(EINVAL);
 203         } else if (dn->dn_bonus != db) {
 204                 error = SET_ERROR(EINVAL);
 205         } else {
 206                 dnode_setbonus_type(dn, type, tx);
 207                 error = 0;
 208         }
 209 
 210         DB_DNODE_EXIT(db);
 211         return (error);
 212 }
 213 
 214 dmu_object_type_t
 215 dmu_get_bonustype(dmu_buf_t *db_fake)
 216 {
 217         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
 218         dnode_t *dn;
 219         dmu_object_type_t type;
 220 
 221         DB_DNODE_ENTER(db);
 222         dn = DB_DNODE(db);
 223         type = dn->dn_bonustype;
 224         DB_DNODE_EXIT(db);
 225 
 226         return (type);
 227 }
 228 
 229 int
 230 dmu_rm_spill(objset_t *os, uint64_t object, dmu_tx_t *tx)
 231 {
 232         dnode_t *dn;
 233         int error;
 234 
 235         error = dnode_hold(os, object, FTAG, &dn);
 236         dbuf_rm_spill(dn, tx);
 237         rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
 238         dnode_rm_spill(dn, tx);
 239         rw_exit(&dn->dn_struct_rwlock);
 240         dnode_rele(dn, FTAG);
 241         return (error);
 242 }
 243 
 244 /*
 245  * returns ENOENT, EIO, or 0.
 246  */
 247 int
 248 dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **dbp)
 249 {
 250         dnode_t *dn;
 251         dmu_buf_impl_t *db;
 252         int error;
 253 
 254         error = dnode_hold(os, object, FTAG, &dn);
 255         if (error)
 256                 return (error);
 257 
 258         rw_enter(&dn->dn_struct_rwlock, RW_READER);
 259         if (dn->dn_bonus == NULL) {
 260                 rw_exit(&dn->dn_struct_rwlock);
 261                 rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
 262                 if (dn->dn_bonus == NULL)
 263                         dbuf_create_bonus(dn);
 264         }
 265         db = dn->dn_bonus;
 266 
 267         /* as long as the bonus buf is held, the dnode will be held */
 268         if (refcount_add(&db->db_holds, tag) == 1) {
 269                 VERIFY(dnode_add_ref(dn, db));
 270                 (void) atomic_inc_32_nv(&dn->dn_dbufs_count);
 271         }
 272 
 273         /*
 274          * Wait to drop dn_struct_rwlock until after adding the bonus dbuf's
 275          * hold and incrementing the dbuf count to ensure that dnode_move() sees
 276          * a dnode hold for every dbuf.
 277          */
 278         rw_exit(&dn->dn_struct_rwlock);
 279 
 280         dnode_rele(dn, FTAG);
 281 
 282         VERIFY(0 == dbuf_read(db, NULL, DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH));
 283 
 284         *dbp = &db->db;
 285         return (0);
 286 }
 287 
 288 /*
 289  * returns ENOENT, EIO, or 0.
 290  *
 291  * This interface will allocate a blank spill dbuf when a spill blk
 292  * doesn't already exist on the dnode.
 293  *
 294  * if you only want to find an already existing spill db, then
 295  * dmu_spill_hold_existing() should be used.
 296  */
 297 int
 298 dmu_spill_hold_by_dnode(dnode_t *dn, uint32_t flags, void *tag, dmu_buf_t **dbp)
 299 {
 300         dmu_buf_impl_t *db = NULL;
 301         int err;
 302 
 303         if ((flags & DB_RF_HAVESTRUCT) == 0)
 304                 rw_enter(&dn->dn_struct_rwlock, RW_READER);
 305 
 306         db = dbuf_hold(dn, DMU_SPILL_BLKID, tag);
 307 
 308         if ((flags & DB_RF_HAVESTRUCT) == 0)
 309                 rw_exit(&dn->dn_struct_rwlock);
 310 
 311         ASSERT(db != NULL);
 312         err = dbuf_read(db, NULL, flags);
 313         if (err == 0)
 314                 *dbp = &db->db;
 315         else
 316                 dbuf_rele(db, tag);
 317         return (err);
 318 }
 319 
 320 int
 321 dmu_spill_hold_existing(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp)
 322 {
 323         dmu_buf_impl_t *db = (dmu_buf_impl_t *)bonus;
 324         dnode_t *dn;
 325         int err;
 326 
 327         DB_DNODE_ENTER(db);
 328         dn = DB_DNODE(db);
 329 
 330         if (spa_version(dn->dn_objset->os_spa) < SPA_VERSION_SA) {
 331                 err = SET_ERROR(EINVAL);
 332         } else {
 333                 rw_enter(&dn->dn_struct_rwlock, RW_READER);
 334 
 335                 if (!dn->dn_have_spill) {
 336                         err = SET_ERROR(ENOENT);
 337                 } else {
 338                         err = dmu_spill_hold_by_dnode(dn,
 339                             DB_RF_HAVESTRUCT | DB_RF_CANFAIL, tag, dbp);
 340                 }
 341 
 342                 rw_exit(&dn->dn_struct_rwlock);
 343         }
 344 
 345         DB_DNODE_EXIT(db);
 346         return (err);
 347 }
 348 
 349 int
 350 dmu_spill_hold_by_bonus(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp)
 351 {
 352         dmu_buf_impl_t *db = (dmu_buf_impl_t *)bonus;
 353         dnode_t *dn;
 354         int err;
 355 
 356         DB_DNODE_ENTER(db);
 357         dn = DB_DNODE(db);
 358         err = dmu_spill_hold_by_dnode(dn, DB_RF_CANFAIL, tag, dbp);
 359         DB_DNODE_EXIT(db);
 360 
 361         return (err);
 362 }
 363 
 364 /*
 365  * Note: longer-term, we should modify all of the dmu_buf_*() interfaces
 366  * to take a held dnode rather than <os, object> -- the lookup is wasteful,
 367  * and can induce severe lock contention when writing to several files
 368  * whose dnodes are in the same block.
 369  */
 370 static int
 371 dmu_buf_hold_array_by_dnode(dnode_t *dn, uint64_t offset, uint64_t length,
 372     int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp, uint32_t flags)
 373 {
 374         dmu_buf_t **dbp;
 375         uint64_t blkid, nblks, i;
 376         uint32_t dbuf_flags;
 377         int err;
 378         zio_t *zio;
 379 
 380         ASSERT(length <= DMU_MAX_ACCESS);
 381 
 382         dbuf_flags = DB_RF_CANFAIL | DB_RF_NEVERWAIT | DB_RF_HAVESTRUCT;
 383         if (flags & DMU_READ_NO_PREFETCH || length > zfetch_array_rd_sz)
 384                 dbuf_flags |= DB_RF_NOPREFETCH;
 385 
 386         rw_enter(&dn->dn_struct_rwlock, RW_READER);
 387         if (dn->dn_datablkshift) {
 388                 int blkshift = dn->dn_datablkshift;
 389                 nblks = (P2ROUNDUP(offset+length, 1ULL<<blkshift) -
 390                     P2ALIGN(offset, 1ULL<<blkshift)) >> blkshift;
 391         } else {
 392                 if (offset + length > dn->dn_datablksz) {
 393                         zfs_panic_recover("zfs: accessing past end of object "
 394                             "%llx/%llx (size=%u access=%llu+%llu)",
 395                             (longlong_t)dn->dn_objset->
 396                             os_dsl_dataset->ds_object,
 397                             (longlong_t)dn->dn_object, dn->dn_datablksz,
 398                             (longlong_t)offset, (longlong_t)length);
 399                         rw_exit(&dn->dn_struct_rwlock);
 400                         return (SET_ERROR(EIO));
 401                 }
 402                 nblks = 1;
 403         }
 404         dbp = kmem_zalloc(sizeof (dmu_buf_t *) * nblks, KM_SLEEP);
 405 
 406         zio = zio_root(dn->dn_objset->os_spa, NULL, NULL, ZIO_FLAG_CANFAIL);
 407         blkid = dbuf_whichblock(dn, offset);
 408         for (i = 0; i < nblks; i++) {
 409                 dmu_buf_impl_t *db = dbuf_hold(dn, blkid+i, tag);
 410                 if (db == NULL) {
 411                         rw_exit(&dn->dn_struct_rwlock);
 412                         dmu_buf_rele_array(dbp, nblks, tag);
 413                         zio_nowait(zio);
 414                         return (SET_ERROR(EIO));
 415                 }
 416                 /* initiate async i/o */
 417                 if (read) {
 418                         (void) dbuf_read(db, zio, dbuf_flags);
 419                 }
 420                 dbp[i] = &db->db;
 421         }
 422         rw_exit(&dn->dn_struct_rwlock);
 423 
 424         /* wait for async i/o */
 425         err = zio_wait(zio);
 426         if (err) {
 427                 dmu_buf_rele_array(dbp, nblks, tag);
 428                 return (err);
 429         }
 430 
 431         /* wait for other io to complete */
 432         if (read) {
 433                 for (i = 0; i < nblks; i++) {
 434                         dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbp[i];
 435                         mutex_enter(&db->db_mtx);
 436                         while (db->db_state == DB_READ ||
 437                             db->db_state == DB_FILL)
 438                                 cv_wait(&db->db_changed, &db->db_mtx);
 439                         if (db->db_state == DB_UNCACHED)
 440                                 err = SET_ERROR(EIO);
 441                         mutex_exit(&db->db_mtx);
 442                         if (err) {
 443                                 dmu_buf_rele_array(dbp, nblks, tag);
 444                                 return (err);
 445                         }
 446                 }
 447         }
 448 
 449         *numbufsp = nblks;
 450         *dbpp = dbp;
 451         return (0);
 452 }
 453 
 454 static int
 455 dmu_buf_hold_array(objset_t *os, uint64_t object, uint64_t offset,
 456     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
 457 {
 458         dnode_t *dn;
 459         int err;
 460 
 461         err = dnode_hold(os, object, FTAG, &dn);
 462         if (err)
 463                 return (err);
 464 
 465         err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
 466             numbufsp, dbpp, DMU_READ_PREFETCH);
 467 
 468         dnode_rele(dn, FTAG);
 469 
 470         return (err);
 471 }
 472 
 473 int
 474 dmu_buf_hold_array_by_bonus(dmu_buf_t *db_fake, uint64_t offset,
 475     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
 476 {
 477         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
 478         dnode_t *dn;
 479         int err;
 480 
 481         DB_DNODE_ENTER(db);
 482         dn = DB_DNODE(db);
 483         err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
 484             numbufsp, dbpp, DMU_READ_PREFETCH);
 485         DB_DNODE_EXIT(db);
 486 
 487         return (err);
 488 }
 489 
 490 void
 491 dmu_buf_rele_array(dmu_buf_t **dbp_fake, int numbufs, void *tag)
 492 {
 493         int i;
 494         dmu_buf_impl_t **dbp = (dmu_buf_impl_t **)dbp_fake;
 495 
 496         if (numbufs == 0)
 497                 return;
 498 
 499         for (i = 0; i < numbufs; i++) {
 500                 if (dbp[i])
 501                         dbuf_rele(dbp[i], tag);
 502         }
 503 
 504         kmem_free(dbp, sizeof (dmu_buf_t *) * numbufs);
 505 }
 506 
 507 /*
 508  * Issue prefetch i/os for the given blocks.
 509  *
 510  * Note: The assumption is that we *know* these blocks will be needed
 511  * almost immediately.  Therefore, the prefetch i/os will be issued at
 512  * ZIO_PRIORITY_SYNC_READ
 513  *
 514  * Note: indirect blocks and other metadata will be read synchronously,
 515  * causing this function to block if they are not already cached.
 516  */
 517 void
 518 dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset, uint64_t len)
 519 {
 520         dnode_t *dn;
 521         uint64_t blkid;
 522         int nblks, err;
 523 
 524         if (zfs_prefetch_disable)
 525                 return;
 526 
 527         if (len == 0) {  /* they're interested in the bonus buffer */
 528                 dn = DMU_META_DNODE(os);
 529 
 530                 if (object == 0 || object >= DN_MAX_OBJECT)
 531                         return;
 532 
 533                 rw_enter(&dn->dn_struct_rwlock, RW_READER);
 534                 blkid = dbuf_whichblock(dn, object * sizeof (dnode_phys_t));
 535                 dbuf_prefetch(dn, blkid, ZIO_PRIORITY_SYNC_READ);
 536                 rw_exit(&dn->dn_struct_rwlock);
 537                 return;
 538         }
 539 
 540         /*
 541          * XXX - Note, if the dnode for the requested object is not
 542          * already cached, we will do a *synchronous* read in the
 543          * dnode_hold() call.  The same is true for any indirects.
 544          */
 545         err = dnode_hold(os, object, FTAG, &dn);
 546         if (err != 0)
 547                 return;
 548 
 549         rw_enter(&dn->dn_struct_rwlock, RW_READER);
 550         if (dn->dn_datablkshift) {
 551                 int blkshift = dn->dn_datablkshift;
 552                 nblks = (P2ROUNDUP(offset + len, 1 << blkshift) -
 553                     P2ALIGN(offset, 1 << blkshift)) >> blkshift;
 554         } else {
 555                 nblks = (offset < dn->dn_datablksz);
 556         }
 557 
 558         if (nblks != 0) {
 559                 blkid = dbuf_whichblock(dn, offset);
 560                 for (int i = 0; i < nblks; i++)
 561                         dbuf_prefetch(dn, blkid + i, ZIO_PRIORITY_SYNC_READ);
 562         }
 563 
 564         rw_exit(&dn->dn_struct_rwlock);
 565 
 566         dnode_rele(dn, FTAG);
 567 }
 568 
 569 /*
 570  * Get the next "chunk" of file data to free.  We traverse the file from
 571  * the end so that the file gets shorter over time (if we crashes in the
 572  * middle, this will leave us in a better state).  We find allocated file
 573  * data by simply searching the allocated level 1 indirects.
 574  *
 575  * On input, *start should be the first offset that does not need to be
 576  * freed (e.g. "offset + length").  On return, *start will be the first
 577  * offset that should be freed.
 578  */
 579 static int
 580 get_next_chunk(dnode_t *dn, uint64_t *start, uint64_t minimum)
 581 {
 582         uint64_t maxblks = DMU_MAX_ACCESS >> (dn->dn_indblkshift + 1);
 583         /* bytes of data covered by a level-1 indirect block */
 584         uint64_t iblkrange =
 585             dn->dn_datablksz * EPB(dn->dn_indblkshift, SPA_BLKPTRSHIFT);
 586 
 587         ASSERT3U(minimum, <=, *start);
 588 
 589         if (*start - minimum <= iblkrange * maxblks) {
 590                 *start = minimum;
 591                 return (0);
 592         }
 593         ASSERT(ISP2(iblkrange));
 594 
 595         for (uint64_t blks = 0; *start > minimum && blks < maxblks; blks++) {
 596                 int err;
 597 
 598                 /*
 599                  * dnode_next_offset(BACKWARDS) will find an allocated L1
 600                  * indirect block at or before the input offset.  We must
 601                  * decrement *start so that it is at the end of the region
 602                  * to search.
 603                  */
 604                 (*start)--;
 605                 err = dnode_next_offset(dn,
 606                     DNODE_FIND_BACKWARDS, start, 2, 1, 0);
 607 
 608                 /* if there are no indirect blocks before start, we are done */
 609                 if (err == ESRCH) {
 610                         *start = minimum;
 611                         break;
 612                 } else if (err != 0) {
 613                         return (err);
 614                 }
 615 
 616                 /* set start to the beginning of this L1 indirect */
 617                 *start = P2ALIGN(*start, iblkrange);
 618         }
 619         if (*start < minimum)
 620                 *start = minimum;
 621         return (0);
 622 }
 623 
 624 static int
 625 dmu_free_long_range_impl(objset_t *os, dnode_t *dn, uint64_t offset,
 626     uint64_t length)
 627 {
 628         uint64_t object_size = (dn->dn_maxblkid + 1) * dn->dn_datablksz;
 629         int err;
 630 
 631         if (offset >= object_size)
 632                 return (0);
 633 
 634         if (length == DMU_OBJECT_END || offset + length > object_size)
 635                 length = object_size - offset;
 636 
 637         while (length != 0) {
 638                 uint64_t chunk_end, chunk_begin;
 639 
 640                 chunk_end = chunk_begin = offset + length;
 641 
 642                 /* move chunk_begin backwards to the beginning of this chunk */
 643                 err = get_next_chunk(dn, &chunk_begin, offset);
 644                 if (err)
 645                         return (err);
 646                 ASSERT3U(chunk_begin, >=, offset);
 647                 ASSERT3U(chunk_begin, <=, chunk_end);
 648 
 649                 dmu_tx_t *tx = dmu_tx_create(os);
 650                 dmu_tx_hold_free(tx, dn->dn_object,
 651                     chunk_begin, chunk_end - chunk_begin);
 652                 err = dmu_tx_assign(tx, TXG_WAIT);
 653                 if (err) {
 654                         dmu_tx_abort(tx);
 655                         return (err);
 656                 }
 657                 dnode_free_range(dn, chunk_begin, chunk_end - chunk_begin, tx);
 658                 dmu_tx_commit(tx);
 659 
 660                 length -= chunk_end - chunk_begin;
 661         }
 662         return (0);
 663 }
 664 
 665 int
 666 dmu_free_long_range(objset_t *os, uint64_t object,
 667     uint64_t offset, uint64_t length)
 668 {
 669         dnode_t *dn;
 670         int err;
 671 
 672         err = dnode_hold(os, object, FTAG, &dn);
 673         if (err != 0)
 674                 return (err);
 675         err = dmu_free_long_range_impl(os, dn, offset, length);
 676 
 677         /*
 678          * It is important to zero out the maxblkid when freeing the entire
 679          * file, so that (a) subsequent calls to dmu_free_long_range_impl()
 680          * will take the fast path, and (b) dnode_reallocate() can verify
 681          * that the entire file has been freed.
 682          */
 683         if (err == 0 && offset == 0 && length == DMU_OBJECT_END)
 684                 dn->dn_maxblkid = 0;
 685 
 686         dnode_rele(dn, FTAG);
 687         return (err);
 688 }
 689 
 690 int
 691 dmu_free_long_object(objset_t *os, uint64_t object)
 692 {
 693         dmu_tx_t *tx;
 694         int err;
 695 
 696         err = dmu_free_long_range(os, object, 0, DMU_OBJECT_END);
 697         if (err != 0)
 698                 return (err);
 699 
 700         tx = dmu_tx_create(os);
 701         dmu_tx_hold_bonus(tx, object);
 702         dmu_tx_hold_free(tx, object, 0, DMU_OBJECT_END);
 703         err = dmu_tx_assign(tx, TXG_WAIT);
 704         if (err == 0) {
 705                 err = dmu_object_free(os, object, tx);
 706                 dmu_tx_commit(tx);
 707         } else {
 708                 dmu_tx_abort(tx);
 709         }
 710 
 711         return (err);
 712 }
 713 
 714 int
 715 dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
 716     uint64_t size, dmu_tx_t *tx)
 717 {
 718         dnode_t *dn;
 719         int err = dnode_hold(os, object, FTAG, &dn);
 720         if (err)
 721                 return (err);
 722         ASSERT(offset < UINT64_MAX);
 723         ASSERT(size == -1ULL || size <= UINT64_MAX - offset);
 724         dnode_free_range(dn, offset, size, tx);
 725         dnode_rele(dn, FTAG);
 726         return (0);
 727 }
 728 
 729 int
 730 dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 731     void *buf, uint32_t flags)
 732 {
 733         dnode_t *dn;
 734         dmu_buf_t **dbp;
 735         int numbufs, err;
 736 
 737         err = dnode_hold(os, object, FTAG, &dn);
 738         if (err)
 739                 return (err);
 740 
 741         /*
 742          * Deal with odd block sizes, where there can't be data past the first
 743          * block.  If we ever do the tail block optimization, we will need to
 744          * handle that here as well.
 745          */
 746         if (dn->dn_maxblkid == 0) {
 747                 int newsz = offset > dn->dn_datablksz ? 0 :
 748                     MIN(size, dn->dn_datablksz - offset);
 749                 bzero((char *)buf + newsz, size - newsz);
 750                 size = newsz;
 751         }
 752 
 753         while (size > 0) {
 754                 uint64_t mylen = MIN(size, DMU_MAX_ACCESS / 2);
 755                 int i;
 756 
 757                 /*
 758                  * NB: we could do this block-at-a-time, but it's nice
 759                  * to be reading in parallel.
 760                  */
 761                 err = dmu_buf_hold_array_by_dnode(dn, offset, mylen,
 762                     TRUE, FTAG, &numbufs, &dbp, flags);
 763                 if (err)
 764                         break;
 765 
 766                 for (i = 0; i < numbufs; i++) {
 767                         int tocpy;
 768                         int bufoff;
 769                         dmu_buf_t *db = dbp[i];
 770 
 771                         ASSERT(size > 0);
 772 
 773                         bufoff = offset - db->db_offset;
 774                         tocpy = (int)MIN(db->db_size - bufoff, size);
 775 
 776                         bcopy((char *)db->db_data + bufoff, buf, tocpy);
 777 
 778                         offset += tocpy;
 779                         size -= tocpy;
 780                         buf = (char *)buf + tocpy;
 781                 }
 782                 dmu_buf_rele_array(dbp, numbufs, FTAG);
 783         }
 784         dnode_rele(dn, FTAG);
 785         return (err);
 786 }
 787 
 788 void
 789 dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 790     const void *buf, dmu_tx_t *tx)
 791 {
 792         dmu_buf_t **dbp;
 793         int numbufs, i;
 794 
 795         if (size == 0)
 796                 return;
 797 
 798         VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
 799             FALSE, FTAG, &numbufs, &dbp));
 800 
 801         for (i = 0; i < numbufs; i++) {
 802                 int tocpy;
 803                 int bufoff;
 804                 dmu_buf_t *db = dbp[i];
 805 
 806                 ASSERT(size > 0);
 807 
 808                 bufoff = offset - db->db_offset;
 809                 tocpy = (int)MIN(db->db_size - bufoff, size);
 810 
 811                 ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
 812 
 813                 if (tocpy == db->db_size)
 814                         dmu_buf_will_fill(db, tx);
 815                 else
 816                         dmu_buf_will_dirty(db, tx);
 817 
 818                 bcopy(buf, (char *)db->db_data + bufoff, tocpy);
 819 
 820                 if (tocpy == db->db_size)
 821                         dmu_buf_fill_done(db, tx);
 822 
 823                 offset += tocpy;
 824                 size -= tocpy;
 825                 buf = (char *)buf + tocpy;
 826         }
 827         dmu_buf_rele_array(dbp, numbufs, FTAG);
 828 }
 829 
 830 void
 831 dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 832     dmu_tx_t *tx)
 833 {
 834         dmu_buf_t **dbp;
 835         int numbufs, i;
 836 
 837         if (size == 0)
 838                 return;
 839 
 840         VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
 841             FALSE, FTAG, &numbufs, &dbp));
 842 
 843         for (i = 0; i < numbufs; i++) {
 844                 dmu_buf_t *db = dbp[i];
 845 
 846                 dmu_buf_will_not_fill(db, tx);
 847         }
 848         dmu_buf_rele_array(dbp, numbufs, FTAG);
 849 }
 850 
 851 /*
 852  * DMU support for xuio
 853  */
 854 kstat_t *xuio_ksp = NULL;
 855 
 856 int
 857 dmu_xuio_init(xuio_t *xuio, int nblk)
 858 {
 859         dmu_xuio_t *priv;
 860         uio_t *uio = &xuio->xu_uio;
 861 
 862         uio->uio_iovcnt = nblk;
 863         uio->uio_iov = kmem_zalloc(nblk * sizeof (iovec_t), KM_SLEEP);
 864 
 865         priv = kmem_zalloc(sizeof (dmu_xuio_t), KM_SLEEP);
 866         priv->cnt = nblk;
 867         priv->bufs = kmem_zalloc(nblk * sizeof (arc_buf_t *), KM_SLEEP);
 868         priv->iovp = uio->uio_iov;
 869         XUIO_XUZC_PRIV(xuio) = priv;
 870 
 871         if (XUIO_XUZC_RW(xuio) == UIO_READ)
 872                 XUIOSTAT_INCR(xuiostat_onloan_rbuf, nblk);
 873         else
 874                 XUIOSTAT_INCR(xuiostat_onloan_wbuf, nblk);
 875 
 876         return (0);
 877 }
 878 
 879 void
 880 dmu_xuio_fini(xuio_t *xuio)
 881 {
 882         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 883         int nblk = priv->cnt;
 884 
 885         kmem_free(priv->iovp, nblk * sizeof (iovec_t));
 886         kmem_free(priv->bufs, nblk * sizeof (arc_buf_t *));
 887         kmem_free(priv, sizeof (dmu_xuio_t));
 888 
 889         if (XUIO_XUZC_RW(xuio) == UIO_READ)
 890                 XUIOSTAT_INCR(xuiostat_onloan_rbuf, -nblk);
 891         else
 892                 XUIOSTAT_INCR(xuiostat_onloan_wbuf, -nblk);
 893 }
 894 
 895 /*
 896  * Initialize iov[priv->next] and priv->bufs[priv->next] with { off, n, abuf }
 897  * and increase priv->next by 1.
 898  */
 899 int
 900 dmu_xuio_add(xuio_t *xuio, arc_buf_t *abuf, offset_t off, size_t n)
 901 {
 902         struct iovec *iov;
 903         uio_t *uio = &xuio->xu_uio;
 904         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 905         int i = priv->next++;
 906 
 907         ASSERT(i < priv->cnt);
 908         ASSERT(off + n <= arc_buf_size(abuf));
 909         iov = uio->uio_iov + i;
 910         iov->iov_base = (char *)abuf->b_data + off;
 911         iov->iov_len = n;
 912         priv->bufs[i] = abuf;
 913         return (0);
 914 }
 915 
 916 int
 917 dmu_xuio_cnt(xuio_t *xuio)
 918 {
 919         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 920         return (priv->cnt);
 921 }
 922 
 923 arc_buf_t *
 924 dmu_xuio_arcbuf(xuio_t *xuio, int i)
 925 {
 926         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 927 
 928         ASSERT(i < priv->cnt);
 929         return (priv->bufs[i]);
 930 }
 931 
 932 void
 933 dmu_xuio_clear(xuio_t *xuio, int i)
 934 {
 935         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 936 
 937         ASSERT(i < priv->cnt);
 938         priv->bufs[i] = NULL;
 939 }
 940 
 941 static void
 942 xuio_stat_init(void)
 943 {
 944         xuio_ksp = kstat_create("zfs", 0, "xuio_stats", "misc",
 945             KSTAT_TYPE_NAMED, sizeof (xuio_stats) / sizeof (kstat_named_t),
 946             KSTAT_FLAG_VIRTUAL);
 947         if (xuio_ksp != NULL) {
 948                 xuio_ksp->ks_data = &xuio_stats;
 949                 kstat_install(xuio_ksp);
 950         }
 951 }
 952 
 953 static void
 954 xuio_stat_fini(void)
 955 {
 956         if (xuio_ksp != NULL) {
 957                 kstat_delete(xuio_ksp);
 958                 xuio_ksp = NULL;
 959         }
 960 }
 961 
 962 void
 963 xuio_stat_wbuf_copied()
 964 {
 965         XUIOSTAT_BUMP(xuiostat_wbuf_copied);
 966 }
 967 
 968 void
 969 xuio_stat_wbuf_nocopy()
 970 {
 971         XUIOSTAT_BUMP(xuiostat_wbuf_nocopy);
 972 }
 973 
 974 #ifdef _KERNEL
 975 int
 976 dmu_read_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size)
 977 {
 978         dmu_buf_t **dbp;
 979         int numbufs, i, err;
 980         xuio_t *xuio = NULL;
 981 
 982         /*
 983          * NB: we could do this block-at-a-time, but it's nice
 984          * to be reading in parallel.
 985          */
 986         err = dmu_buf_hold_array(os, object, uio->uio_loffset, size, TRUE, FTAG,
 987             &numbufs, &dbp);
 988         if (err)
 989                 return (err);
 990 
 991         if (uio->uio_extflg == UIO_XUIO)
 992                 xuio = (xuio_t *)uio;
 993 
 994         for (i = 0; i < numbufs; i++) {
 995                 int tocpy;
 996                 int bufoff;
 997                 dmu_buf_t *db = dbp[i];
 998 
 999                 ASSERT(size > 0);
1000 
1001                 bufoff = uio->uio_loffset - db->db_offset;
1002                 tocpy = (int)MIN(db->db_size - bufoff, size);
1003 
1004                 if (xuio) {
1005                         dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
1006                         arc_buf_t *dbuf_abuf = dbi->db_buf;
1007                         arc_buf_t *abuf = dbuf_loan_arcbuf(dbi);
1008                         err = dmu_xuio_add(xuio, abuf, bufoff, tocpy);
1009                         if (!err) {
1010                                 uio->uio_resid -= tocpy;
1011                                 uio->uio_loffset += tocpy;
1012                         }
1013 
1014                         if (abuf == dbuf_abuf)
1015                                 XUIOSTAT_BUMP(xuiostat_rbuf_nocopy);
1016                         else
1017                                 XUIOSTAT_BUMP(xuiostat_rbuf_copied);
1018                 } else {
1019                         err = uiomove((char *)db->db_data + bufoff, tocpy,
1020                             UIO_READ, uio);
1021                 }
1022                 if (err)
1023                         break;
1024 
1025                 size -= tocpy;
1026         }
1027         dmu_buf_rele_array(dbp, numbufs, FTAG);
1028 
1029         return (err);
1030 }
1031 
1032 static int
1033 dmu_write_uio_dnode(dnode_t *dn, uio_t *uio, uint64_t size, dmu_tx_t *tx)
1034 {
1035         dmu_buf_t **dbp;
1036         int numbufs;
1037         int err = 0;
1038         int i;
1039 
1040         err = dmu_buf_hold_array_by_dnode(dn, uio->uio_loffset, size,
1041             FALSE, FTAG, &numbufs, &dbp, DMU_READ_PREFETCH);
1042         if (err)
1043                 return (err);
1044 
1045         for (i = 0; i < numbufs; i++) {
1046                 int tocpy;
1047                 int bufoff;
1048                 dmu_buf_t *db = dbp[i];
1049 
1050                 ASSERT(size > 0);
1051 
1052                 bufoff = uio->uio_loffset - db->db_offset;
1053                 tocpy = (int)MIN(db->db_size - bufoff, size);
1054 
1055                 ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
1056 
1057                 if (tocpy == db->db_size)
1058                         dmu_buf_will_fill(db, tx);
1059                 else
1060                         dmu_buf_will_dirty(db, tx);
1061 
1062                 /*
1063                  * XXX uiomove could block forever (eg. nfs-backed
1064                  * pages).  There needs to be a uiolockdown() function
1065                  * to lock the pages in memory, so that uiomove won't
1066                  * block.
1067                  */
1068                 err = uiomove((char *)db->db_data + bufoff, tocpy,
1069                     UIO_WRITE, uio);
1070 
1071                 if (tocpy == db->db_size)
1072                         dmu_buf_fill_done(db, tx);
1073 
1074                 if (err)
1075                         break;
1076 
1077                 size -= tocpy;
1078         }
1079 
1080         dmu_buf_rele_array(dbp, numbufs, FTAG);
1081         return (err);
1082 }
1083 
1084 int
1085 dmu_write_uio_dbuf(dmu_buf_t *zdb, uio_t *uio, uint64_t size,
1086     dmu_tx_t *tx)
1087 {
1088         dmu_buf_impl_t *db = (dmu_buf_impl_t *)zdb;
1089         dnode_t *dn;
1090         int err;
1091 
1092         if (size == 0)
1093                 return (0);
1094 
1095         DB_DNODE_ENTER(db);
1096         dn = DB_DNODE(db);
1097         err = dmu_write_uio_dnode(dn, uio, size, tx);
1098         DB_DNODE_EXIT(db);
1099 
1100         return (err);
1101 }
1102 
1103 int
1104 dmu_write_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size,
1105     dmu_tx_t *tx)
1106 {
1107         dnode_t *dn;
1108         int err;
1109 
1110         if (size == 0)
1111                 return (0);
1112 
1113         err = dnode_hold(os, object, FTAG, &dn);
1114         if (err)
1115                 return (err);
1116 
1117         err = dmu_write_uio_dnode(dn, uio, size, tx);
1118 
1119         dnode_rele(dn, FTAG);
1120 
1121         return (err);
1122 }
1123 
1124 int
1125 dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
1126     page_t *pp, dmu_tx_t *tx)
1127 {
1128         dmu_buf_t **dbp;
1129         int numbufs, i;
1130         int err;
1131 
1132         if (size == 0)
1133                 return (0);
1134 
1135         err = dmu_buf_hold_array(os, object, offset, size,
1136             FALSE, FTAG, &numbufs, &dbp);
1137         if (err)
1138                 return (err);
1139 
1140         for (i = 0; i < numbufs; i++) {
1141                 int tocpy, copied, thiscpy;
1142                 int bufoff;
1143                 dmu_buf_t *db = dbp[i];
1144                 caddr_t va;
1145 
1146                 ASSERT(size > 0);
1147                 ASSERT3U(db->db_size, >=, PAGESIZE);
1148 
1149                 bufoff = offset - db->db_offset;
1150                 tocpy = (int)MIN(db->db_size - bufoff, size);
1151 
1152                 ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
1153 
1154                 if (tocpy == db->db_size)
1155                         dmu_buf_will_fill(db, tx);
1156                 else
1157                         dmu_buf_will_dirty(db, tx);
1158 
1159                 for (copied = 0; copied < tocpy; copied += PAGESIZE) {
1160                         ASSERT3U(pp->p_offset, ==, db->db_offset + bufoff);
1161                         thiscpy = MIN(PAGESIZE, tocpy - copied);
1162                         va = zfs_map_page(pp, S_READ);
1163                         bcopy(va, (char *)db->db_data + bufoff, thiscpy);
1164                         zfs_unmap_page(pp, va);
1165                         pp = pp->p_next;
1166                         bufoff += PAGESIZE;
1167                 }
1168 
1169                 if (tocpy == db->db_size)
1170                         dmu_buf_fill_done(db, tx);
1171 
1172                 offset += tocpy;
1173                 size -= tocpy;
1174         }
1175         dmu_buf_rele_array(dbp, numbufs, FTAG);
1176         return (err);
1177 }
1178 #endif
1179 
1180 /*
1181  * Allocate a loaned anonymous arc buffer.
1182  */
1183 arc_buf_t *
1184 dmu_request_arcbuf(dmu_buf_t *handle, int size)
1185 {
1186         dmu_buf_impl_t *db = (dmu_buf_impl_t *)handle;
1187 
1188         return (arc_loan_buf(db->db_objset->os_spa, size));
1189 }
1190 
1191 /*
1192  * Free a loaned arc buffer.
1193  */
1194 void
1195 dmu_return_arcbuf(arc_buf_t *buf)
1196 {
1197         arc_return_buf(buf, FTAG);
1198         VERIFY(arc_buf_remove_ref(buf, FTAG));
1199 }
1200 
1201 /*
1202  * When possible directly assign passed loaned arc buffer to a dbuf.
1203  * If this is not possible copy the contents of passed arc buf via
1204  * dmu_write().
1205  */
1206 void
1207 dmu_assign_arcbuf(dmu_buf_t *handle, uint64_t offset, arc_buf_t *buf,
1208     dmu_tx_t *tx)
1209 {
1210         dmu_buf_impl_t *dbuf = (dmu_buf_impl_t *)handle;
1211         dnode_t *dn;
1212         dmu_buf_impl_t *db;
1213         uint32_t blksz = (uint32_t)arc_buf_size(buf);
1214         uint64_t blkid;
1215 
1216         DB_DNODE_ENTER(dbuf);
1217         dn = DB_DNODE(dbuf);
1218         rw_enter(&dn->dn_struct_rwlock, RW_READER);
1219         blkid = dbuf_whichblock(dn, offset);
1220         VERIFY((db = dbuf_hold(dn, blkid, FTAG)) != NULL);
1221         rw_exit(&dn->dn_struct_rwlock);
1222         DB_DNODE_EXIT(dbuf);
1223 
1224         if (offset == db->db.db_offset && blksz == db->db.db_size) {
1225                 dbuf_assign_arcbuf(db, buf, tx);
1226                 dbuf_rele(db, FTAG);
1227         } else {
1228                 objset_t *os;
1229                 uint64_t object;
1230 
1231                 DB_DNODE_ENTER(dbuf);
1232                 dn = DB_DNODE(dbuf);
1233                 os = dn->dn_objset;
1234                 object = dn->dn_object;
1235                 DB_DNODE_EXIT(dbuf);
1236 
1237                 dbuf_rele(db, FTAG);
1238                 dmu_write(os, object, offset, blksz, buf->b_data, tx);
1239                 dmu_return_arcbuf(buf);
1240                 XUIOSTAT_BUMP(xuiostat_wbuf_copied);
1241         }
1242 }
1243 
1244 typedef struct {
1245         dbuf_dirty_record_t     *dsa_dr;
1246         dmu_sync_cb_t           *dsa_done;
1247         zgd_t                   *dsa_zgd;
1248         dmu_tx_t                *dsa_tx;
1249 } dmu_sync_arg_t;
1250 
1251 /* ARGSUSED */
1252 static void
1253 dmu_sync_ready(zio_t *zio, arc_buf_t *buf, void *varg)
1254 {
1255         dmu_sync_arg_t *dsa = varg;
1256         dmu_buf_t *db = dsa->dsa_zgd->zgd_db;
1257         blkptr_t *bp = zio->io_bp;
1258 
1259         if (zio->io_error == 0) {
1260                 if (BP_IS_HOLE(bp)) {
1261                         /*
1262                          * A block of zeros may compress to a hole, but the
1263                          * block size still needs to be known for replay.
1264                          */
1265                         BP_SET_LSIZE(bp, db->db_size);
1266                 } else {
1267                         ASSERT(BP_GET_LEVEL(bp) == 0);
1268                         bp->blk_fill = 1;
1269                 }
1270         }
1271 }
1272 
1273 static void
1274 dmu_sync_late_arrival_ready(zio_t *zio)
1275 {
1276         dmu_sync_ready(zio, NULL, zio->io_private);
1277 }
1278 
1279 /* ARGSUSED */
1280 static void
1281 dmu_sync_done(zio_t *zio, arc_buf_t *buf, void *varg)
1282 {
1283         dmu_sync_arg_t *dsa = varg;
1284         dbuf_dirty_record_t *dr = dsa->dsa_dr;
1285         dmu_buf_impl_t *db = dr->dr_dbuf;
1286 
1287         mutex_enter(&db->db_mtx);
1288         ASSERT(dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC);
1289         if (zio->io_error == 0) {
1290                 dr->dt.dl.dr_nopwrite = !!(zio->io_flags & ZIO_FLAG_NOPWRITE);
1291                 if (dr->dt.dl.dr_nopwrite) {
1292                         blkptr_t *bp = zio->io_bp;
1293                         blkptr_t *bp_orig = &zio->io_bp_orig;
1294                         uint8_t chksum = BP_GET_CHECKSUM(bp_orig);
1295 
1296                         ASSERT(BP_EQUAL(bp, bp_orig));
1297                         ASSERT(zio->io_prop.zp_compress != ZIO_COMPRESS_OFF);
1298                         ASSERT(zio_checksum_table[chksum].ci_dedup);
1299                 }
1300                 dr->dt.dl.dr_overridden_by = *zio->io_bp;
1301                 dr->dt.dl.dr_override_state = DR_OVERRIDDEN;
1302                 dr->dt.dl.dr_copies = zio->io_prop.zp_copies;
1303                 if (BP_IS_HOLE(&dr->dt.dl.dr_overridden_by))
1304                         BP_ZERO(&dr->dt.dl.dr_overridden_by);
1305         } else {
1306                 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
1307         }
1308         cv_broadcast(&db->db_changed);
1309         mutex_exit(&db->db_mtx);
1310 
1311         dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
1312 
1313         kmem_free(dsa, sizeof (*dsa));
1314 }
1315 
1316 static void
1317 dmu_sync_late_arrival_done(zio_t *zio)
1318 {
1319         blkptr_t *bp = zio->io_bp;
1320         dmu_sync_arg_t *dsa = zio->io_private;
1321         blkptr_t *bp_orig = &zio->io_bp_orig;
1322 
1323         if (zio->io_error == 0 && !BP_IS_HOLE(bp)) {
1324                 /*
1325                  * If we didn't allocate a new block (i.e. ZIO_FLAG_NOPWRITE)
1326                  * then there is nothing to do here. Otherwise, free the
1327                  * newly allocated block in this txg.
1328                  */
1329                 if (zio->io_flags & ZIO_FLAG_NOPWRITE) {
1330                         ASSERT(BP_EQUAL(bp, bp_orig));
1331                 } else {
1332                         ASSERT(BP_IS_HOLE(bp_orig) || !BP_EQUAL(bp, bp_orig));
1333                         ASSERT(zio->io_bp->blk_birth == zio->io_txg);
1334                         ASSERT(zio->io_txg > spa_syncing_txg(zio->io_spa));
1335                         zio_free(zio->io_spa, zio->io_txg, zio->io_bp);
1336                 }
1337         }
1338 
1339         dmu_tx_commit(dsa->dsa_tx);
1340 
1341         dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
1342 
1343         kmem_free(dsa, sizeof (*dsa));
1344 }
1345 
1346 static int
1347 dmu_sync_late_arrival(zio_t *pio, objset_t *os, dmu_sync_cb_t *done, zgd_t *zgd,
1348     zio_prop_t *zp, zbookmark_t *zb)
1349 {
1350         dmu_sync_arg_t *dsa;
1351         dmu_tx_t *tx;
1352 
1353         tx = dmu_tx_create(os);
1354         dmu_tx_hold_space(tx, zgd->zgd_db->db_size);
1355         if (dmu_tx_assign(tx, TXG_WAIT) != 0) {
1356                 dmu_tx_abort(tx);
1357                 /* Make zl_get_data do txg_waited_synced() */
1358                 return (SET_ERROR(EIO));
1359         }
1360 
1361         dsa = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
1362         dsa->dsa_dr = NULL;
1363         dsa->dsa_done = done;
1364         dsa->dsa_zgd = zgd;
1365         dsa->dsa_tx = tx;
1366 
1367         zio_nowait(zio_write(pio, os->os_spa, dmu_tx_get_txg(tx), zgd->zgd_bp,
1368             zgd->zgd_db->db_data, zgd->zgd_db->db_size, zp,
1369             dmu_sync_late_arrival_ready, NULL, dmu_sync_late_arrival_done, dsa,
1370             ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_CANFAIL, zb));
1371 
1372         return (0);
1373 }
1374 
1375 /*
1376  * Intent log support: sync the block associated with db to disk.
1377  * N.B. and XXX: the caller is responsible for making sure that the
1378  * data isn't changing while dmu_sync() is writing it.
1379  *
1380  * Return values:
1381  *
1382  *      EEXIST: this txg has already been synced, so there's nothing to do.
1383  *              The caller should not log the write.
1384  *
1385  *      ENOENT: the block was dbuf_free_range()'d, so there's nothing to do.
1386  *              The caller should not log the write.
1387  *
1388  *      EALREADY: this block is already in the process of being synced.
1389  *              The caller should track its progress (somehow).
1390  *
1391  *      EIO: could not do the I/O.
1392  *              The caller should do a txg_wait_synced().
1393  *
1394  *      0: the I/O has been initiated.
1395  *              The caller should log this blkptr in the done callback.
1396  *              It is possible that the I/O will fail, in which case
1397  *              the error will be reported to the done callback and
1398  *              propagated to pio from zio_done().
1399  */
1400 int
1401 dmu_sync(zio_t *pio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd)
1402 {
1403         blkptr_t *bp = zgd->zgd_bp;
1404         dmu_buf_impl_t *db = (dmu_buf_impl_t *)zgd->zgd_db;
1405         objset_t *os = db->db_objset;
1406         dsl_dataset_t *ds = os->os_dsl_dataset;
1407         dbuf_dirty_record_t *dr;
1408         dmu_sync_arg_t *dsa;
1409         zbookmark_t zb;
1410         zio_prop_t zp;
1411         dnode_t *dn;
1412 
1413         ASSERT(pio != NULL);
1414         ASSERT(txg != 0);
1415 
1416         SET_BOOKMARK(&zb, ds->ds_object,
1417             db->db.db_object, db->db_level, db->db_blkid);
1418 
1419         DB_DNODE_ENTER(db);
1420         dn = DB_DNODE(db);
1421         dmu_write_policy(os, dn, db->db_level, WP_DMU_SYNC, &zp);
1422         DB_DNODE_EXIT(db);
1423 
1424         /*
1425          * If we're frozen (running ziltest), we always need to generate a bp.
1426          */
1427         if (txg > spa_freeze_txg(os->os_spa))
1428                 return (dmu_sync_late_arrival(pio, os, done, zgd, &zp, &zb));
1429 
1430         /*
1431          * Grabbing db_mtx now provides a barrier between dbuf_sync_leaf()
1432          * and us.  If we determine that this txg is not yet syncing,
1433          * but it begins to sync a moment later, that's OK because the
1434          * sync thread will block in dbuf_sync_leaf() until we drop db_mtx.
1435          */
1436         mutex_enter(&db->db_mtx);
1437 
1438         if (txg <= spa_last_synced_txg(os->os_spa)) {
1439                 /*
1440                  * This txg has already synced.  There's nothing to do.
1441                  */
1442                 mutex_exit(&db->db_mtx);
1443                 return (SET_ERROR(EEXIST));
1444         }
1445 
1446         if (txg <= spa_syncing_txg(os->os_spa)) {
1447                 /*
1448                  * This txg is currently syncing, so we can't mess with
1449                  * the dirty record anymore; just write a new log block.
1450                  */
1451                 mutex_exit(&db->db_mtx);
1452                 return (dmu_sync_late_arrival(pio, os, done, zgd, &zp, &zb));
1453         }
1454 
1455         dr = db->db_last_dirty;
1456         while (dr && dr->dr_txg != txg)
1457                 dr = dr->dr_next;
1458 
1459         if (dr == NULL) {
1460                 /*
1461                  * There's no dr for this dbuf, so it must have been freed.
1462                  * There's no need to log writes to freed blocks, so we're done.
1463                  */
1464                 mutex_exit(&db->db_mtx);
1465                 return (SET_ERROR(ENOENT));
1466         }
1467 
1468         ASSERT(dr->dr_next == NULL || dr->dr_next->dr_txg < txg);
1469 
1470         /*
1471          * Assume the on-disk data is X, the current syncing data is Y,
1472          * and the current in-memory data is Z (currently in dmu_sync).
1473          * X and Z are identical but Y is has been modified. Normally,
1474          * when X and Z are the same we will perform a nopwrite but if Y
1475          * is different we must disable nopwrite since the resulting write
1476          * of Y to disk can free the block containing X. If we allowed a
1477          * nopwrite to occur the block pointing to Z would reference a freed
1478          * block. Since this is a rare case we simplify this by disabling
1479          * nopwrite if the current dmu_sync-ing dbuf has been modified in
1480          * a previous transaction.
1481          */
1482         if (dr->dr_next)
1483                 zp.zp_nopwrite = B_FALSE;
1484 
1485         ASSERT(dr->dr_txg == txg);
1486         if (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC ||
1487             dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
1488                 /*
1489                  * We have already issued a sync write for this buffer,
1490                  * or this buffer has already been synced.  It could not
1491                  * have been dirtied since, or we would have cleared the state.
1492                  */
1493                 mutex_exit(&db->db_mtx);
1494                 return (SET_ERROR(EALREADY));
1495         }
1496 
1497         ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
1498         dr->dt.dl.dr_override_state = DR_IN_DMU_SYNC;
1499         mutex_exit(&db->db_mtx);
1500 
1501         dsa = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
1502         dsa->dsa_dr = dr;
1503         dsa->dsa_done = done;
1504         dsa->dsa_zgd = zgd;
1505         dsa->dsa_tx = NULL;
1506 
1507         zio_nowait(arc_write(pio, os->os_spa, txg,
1508             bp, dr->dt.dl.dr_data, DBUF_IS_L2CACHEABLE(db),
1509             DBUF_IS_L2COMPRESSIBLE(db), &zp, dmu_sync_ready,
1510             NULL, dmu_sync_done, dsa, ZIO_PRIORITY_SYNC_WRITE,
1511             ZIO_FLAG_CANFAIL, &zb));
1512 
1513         return (0);
1514 }
1515 
1516 int
1517 dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size, int ibs,
1518         dmu_tx_t *tx)
1519 {
1520         dnode_t *dn;
1521         int err;
1522 
1523         err = dnode_hold(os, object, FTAG, &dn);
1524         if (err)
1525                 return (err);
1526         err = dnode_set_blksz(dn, size, ibs, tx);
1527         dnode_rele(dn, FTAG);
1528         return (err);
1529 }
1530 
1531 void
1532 dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
1533         dmu_tx_t *tx)
1534 {
1535         dnode_t *dn;
1536 
1537         /* XXX assumes dnode_hold will not get an i/o error */
1538         (void) dnode_hold(os, object, FTAG, &dn);
1539         ASSERT(checksum < ZIO_CHECKSUM_FUNCTIONS);
1540         dn->dn_checksum = checksum;
1541         dnode_setdirty(dn, tx);
1542         dnode_rele(dn, FTAG);
1543 }
1544 
1545 void
1546 dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
1547         dmu_tx_t *tx)
1548 {
1549         dnode_t *dn;
1550 
1551         /* XXX assumes dnode_hold will not get an i/o error */
1552         (void) dnode_hold(os, object, FTAG, &dn);
1553         ASSERT(compress < ZIO_COMPRESS_FUNCTIONS);
1554         dn->dn_compress = compress;
1555         dnode_setdirty(dn, tx);
1556         dnode_rele(dn, FTAG);
1557 }
1558 
1559 int zfs_mdcomp_disable = 0;
1560 
1561 /*
1562  * When the "redundant_metadata" property is set to "most", only indirect
1563  * blocks of this level and higher will have an additional ditto block.
1564  */
1565 int zfs_redundant_metadata_most_ditto_level = 2;
1566 
1567 void
1568 dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp, zio_prop_t *zp)
1569 {
1570         dmu_object_type_t type = dn ? dn->dn_type : DMU_OT_OBJSET;
1571         boolean_t ismd = (level > 0 || DMU_OT_IS_METADATA(type) ||
1572             (wp & WP_SPILL));
1573         enum zio_checksum checksum = os->os_checksum;
1574         enum zio_compress compress = os->os_compress;
1575         enum zio_checksum dedup_checksum = os->os_dedup_checksum;
1576         boolean_t dedup = B_FALSE;
1577         boolean_t nopwrite = B_FALSE;
1578         boolean_t dedup_verify = os->os_dedup_verify;
1579         int copies = os->os_copies;
1580 
1581         /*
1582          * We maintain different write policies for each of the following
1583          * types of data:
1584          *       1. metadata
1585          *       2. preallocated blocks (i.e. level-0 blocks of a dump device)
1586          *       3. all other level 0 blocks
1587          */
1588         if (ismd) {
1589                 /*
1590                  * XXX -- we should design a compression algorithm
1591                  * that specializes in arrays of bps.
1592                  */
1593                 compress = zfs_mdcomp_disable ? ZIO_COMPRESS_EMPTY :
1594                     ZIO_COMPRESS_LZJB;
1595 
1596                 /*
1597                  * Metadata always gets checksummed.  If the data
1598                  * checksum is multi-bit correctable, and it's not a
1599                  * ZBT-style checksum, then it's suitable for metadata
1600                  * as well.  Otherwise, the metadata checksum defaults
1601                  * to fletcher4.
1602                  */
1603                 if (zio_checksum_table[checksum].ci_correctable < 1 ||
1604                     zio_checksum_table[checksum].ci_eck)
1605                         checksum = ZIO_CHECKSUM_FLETCHER_4;
1606 
1607                 if (os->os_redundant_metadata == ZFS_REDUNDANT_METADATA_ALL ||
1608                     (os->os_redundant_metadata ==
1609                     ZFS_REDUNDANT_METADATA_MOST &&
1610                     (level >= zfs_redundant_metadata_most_ditto_level ||
1611                     DMU_OT_IS_METADATA(type) || (wp & WP_SPILL))))
1612                         copies++;
1613         } else if (wp & WP_NOFILL) {
1614                 ASSERT(level == 0);
1615 
1616                 /*
1617                  * If we're writing preallocated blocks, we aren't actually
1618                  * writing them so don't set any policy properties.  These
1619                  * blocks are currently only used by an external subsystem
1620                  * outside of zfs (i.e. dump) and not written by the zio
1621                  * pipeline.
1622                  */
1623                 compress = ZIO_COMPRESS_OFF;
1624                 checksum = ZIO_CHECKSUM_NOPARITY;
1625         } else {
1626                 compress = zio_compress_select(dn->dn_compress, compress);
1627 
1628                 checksum = (dedup_checksum == ZIO_CHECKSUM_OFF) ?
1629                     zio_checksum_select(dn->dn_checksum, checksum) :
1630                     dedup_checksum;
1631 
1632                 /*
1633                  * Determine dedup setting.  If we are in dmu_sync(),
1634                  * we won't actually dedup now because that's all
1635                  * done in syncing context; but we do want to use the
1636                  * dedup checkum.  If the checksum is not strong
1637                  * enough to ensure unique signatures, force
1638                  * dedup_verify.
1639                  */
1640                 if (dedup_checksum != ZIO_CHECKSUM_OFF) {
1641                         dedup = (wp & WP_DMU_SYNC) ? B_FALSE : B_TRUE;
1642                         if (!zio_checksum_table[checksum].ci_dedup)
1643                                 dedup_verify = B_TRUE;
1644                 }
1645 
1646                 /*
1647                  * Enable nopwrite if we have a cryptographically secure
1648                  * checksum that has no known collisions (i.e. SHA-256)
1649                  * and compression is enabled.  We don't enable nopwrite if
1650                  * dedup is enabled as the two features are mutually exclusive.
1651                  */
1652                 nopwrite = (!dedup && zio_checksum_table[checksum].ci_dedup &&
1653                     compress != ZIO_COMPRESS_OFF && zfs_nopwrite_enabled);
1654         }
1655 
1656         zp->zp_checksum = checksum;
1657         zp->zp_compress = compress;
1658         zp->zp_type = (wp & WP_SPILL) ? dn->dn_bonustype : type;
1659         zp->zp_level = level;
1660         zp->zp_copies = MIN(copies, spa_max_replication(os->os_spa));
1661         zp->zp_dedup = dedup;
1662         zp->zp_dedup_verify = dedup && dedup_verify;
1663         zp->zp_nopwrite = nopwrite;
1664 }
1665 
1666 int
1667 dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole, uint64_t *off)
1668 {
1669         dnode_t *dn;
1670         int i, err;
1671 
1672         err = dnode_hold(os, object, FTAG, &dn);
1673         if (err)
1674                 return (err);
1675         /*
1676          * Sync any current changes before
1677          * we go trundling through the block pointers.
1678          */
1679         for (i = 0; i < TXG_SIZE; i++) {
1680                 if (list_link_active(&dn->dn_dirty_link[i]))
1681                         break;
1682         }
1683         if (i != TXG_SIZE) {
1684                 dnode_rele(dn, FTAG);
1685                 txg_wait_synced(dmu_objset_pool(os), 0);
1686                 err = dnode_hold(os, object, FTAG, &dn);
1687                 if (err)
1688                         return (err);
1689         }
1690 
1691         err = dnode_next_offset(dn, (hole ? DNODE_FIND_HOLE : 0), off, 1, 1, 0);
1692         dnode_rele(dn, FTAG);
1693 
1694         return (err);
1695 }
1696 
1697 void
1698 dmu_object_info_from_dnode(dnode_t *dn, dmu_object_info_t *doi)
1699 {
1700         dnode_phys_t *dnp;
1701 
1702         rw_enter(&dn->dn_struct_rwlock, RW_READER);
1703         mutex_enter(&dn->dn_mtx);
1704 
1705         dnp = dn->dn_phys;
1706 
1707         doi->doi_data_block_size = dn->dn_datablksz;
1708         doi->doi_metadata_block_size = dn->dn_indblkshift ?
1709             1ULL << dn->dn_indblkshift : 0;
1710         doi->doi_type = dn->dn_type;
1711         doi->doi_bonus_type = dn->dn_bonustype;
1712         doi->doi_bonus_size = dn->dn_bonuslen;
1713         doi->doi_indirection = dn->dn_nlevels;
1714         doi->doi_checksum = dn->dn_checksum;
1715         doi->doi_compress = dn->dn_compress;
1716         doi->doi_physical_blocks_512 = (DN_USED_BYTES(dnp) + 256) >> 9;
1717         doi->doi_max_offset = (dn->dn_maxblkid + 1) * dn->dn_datablksz;
1718         doi->doi_fill_count = 0;
1719         for (int i = 0; i < dnp->dn_nblkptr; i++)
1720                 doi->doi_fill_count += dnp->dn_blkptr[i].blk_fill;
1721 
1722         mutex_exit(&dn->dn_mtx);
1723         rw_exit(&dn->dn_struct_rwlock);
1724 }
1725 
1726 /*
1727  * Get information on a DMU object.
1728  * If doi is NULL, just indicates whether the object exists.
1729  */
1730 int
1731 dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi)
1732 {
1733         dnode_t *dn;
1734         int err = dnode_hold(os, object, FTAG, &dn);
1735 
1736         if (err)
1737                 return (err);
1738 
1739         if (doi != NULL)
1740                 dmu_object_info_from_dnode(dn, doi);
1741 
1742         dnode_rele(dn, FTAG);
1743         return (0);
1744 }
1745 
1746 /*
1747  * As above, but faster; can be used when you have a held dbuf in hand.
1748  */
1749 void
1750 dmu_object_info_from_db(dmu_buf_t *db_fake, dmu_object_info_t *doi)
1751 {
1752         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1753 
1754         DB_DNODE_ENTER(db);
1755         dmu_object_info_from_dnode(DB_DNODE(db), doi);
1756         DB_DNODE_EXIT(db);
1757 }
1758 
1759 /*
1760  * Faster still when you only care about the size.
1761  * This is specifically optimized for zfs_getattr().
1762  */
1763 void
1764 dmu_object_size_from_db(dmu_buf_t *db_fake, uint32_t *blksize,
1765     u_longlong_t *nblk512)
1766 {
1767         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1768         dnode_t *dn;
1769 
1770         DB_DNODE_ENTER(db);
1771         dn = DB_DNODE(db);
1772 
1773         *blksize = dn->dn_datablksz;
1774         /* add 1 for dnode space */
1775         *nblk512 = ((DN_USED_BYTES(dn->dn_phys) + SPA_MINBLOCKSIZE/2) >>
1776             SPA_MINBLOCKSHIFT) + 1;
1777         DB_DNODE_EXIT(db);
1778 }
1779 
1780 void
1781 byteswap_uint64_array(void *vbuf, size_t size)
1782 {
1783         uint64_t *buf = vbuf;
1784         size_t count = size >> 3;
1785         int i;
1786 
1787         ASSERT((size & 7) == 0);
1788 
1789         for (i = 0; i < count; i++)
1790                 buf[i] = BSWAP_64(buf[i]);
1791 }
1792 
1793 void
1794 byteswap_uint32_array(void *vbuf, size_t size)
1795 {
1796         uint32_t *buf = vbuf;
1797         size_t count = size >> 2;
1798         int i;
1799 
1800         ASSERT((size & 3) == 0);
1801 
1802         for (i = 0; i < count; i++)
1803                 buf[i] = BSWAP_32(buf[i]);
1804 }
1805 
1806 void
1807 byteswap_uint16_array(void *vbuf, size_t size)
1808 {
1809         uint16_t *buf = vbuf;
1810         size_t count = size >> 1;
1811         int i;
1812 
1813         ASSERT((size & 1) == 0);
1814 
1815         for (i = 0; i < count; i++)
1816                 buf[i] = BSWAP_16(buf[i]);
1817 }
1818 
1819 /* ARGSUSED */
1820 void
1821 byteswap_uint8_array(void *vbuf, size_t size)
1822 {
1823 }
1824 
1825 void
1826 dmu_init(void)
1827 {
1828         zfs_dbgmsg_init();
1829         sa_cache_init();
1830         xuio_stat_init();
1831         dmu_objset_init();
1832         dnode_init();
1833         dbuf_init();
1834         zfetch_init();
1835         l2arc_init();
1836         arc_init();
1837 }
1838 
1839 void
1840 dmu_fini(void)
1841 {
1842         arc_fini(); /* arc depends on l2arc, so arc must go first */
1843         l2arc_fini();
1844         zfetch_fini();
1845         dbuf_fini();
1846         dnode_fini();
1847         dmu_objset_fini();
1848         xuio_stat_fini();
1849         sa_cache_fini();
1850         zfs_dbgmsg_fini();
1851 }