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) 2013 by Delphix. All rights reserved.
  24  * Copyright (c) 2013 Martin Matuska. All rights reserved.
  25  */
  26 
  27 #include <sys/dmu.h>
  28 #include <sys/dmu_impl.h>
  29 #include <sys/dmu_tx.h>
  30 #include <sys/dbuf.h>
  31 #include <sys/dnode.h>
  32 #include <sys/zfs_context.h>
  33 #include <sys/dmu_objset.h>
  34 #include <sys/dmu_traverse.h>
  35 #include <sys/dsl_dataset.h>
  36 #include <sys/dsl_dir.h>
  37 #include <sys/dsl_pool.h>
  38 #include <sys/dsl_synctask.h>
  39 #include <sys/dsl_prop.h>
  40 #include <sys/dmu_zfetch.h>
  41 #include <sys/zfs_ioctl.h>
  42 #include <sys/zap.h>
  43 #include <sys/zio_checksum.h>
  44 #include <sys/zio_compress.h>
  45 #include <sys/sa.h>
  46 #include <sys/zfeature.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         dsl_pool_t *dp = NULL;
 375         dmu_buf_t **dbp;
 376         uint64_t blkid, nblks, i;
 377         uint32_t dbuf_flags;
 378         int err;
 379         zio_t *zio;
 380         hrtime_t start;
 381 
 382         ASSERT(length <= DMU_MAX_ACCESS);
 383 
 384         dbuf_flags = DB_RF_CANFAIL | DB_RF_NEVERWAIT | DB_RF_HAVESTRUCT;
 385         if (flags & DMU_READ_NO_PREFETCH || length > zfetch_array_rd_sz)
 386                 dbuf_flags |= DB_RF_NOPREFETCH;
 387 
 388         rw_enter(&dn->dn_struct_rwlock, RW_READER);
 389         if (dn->dn_datablkshift) {
 390                 int blkshift = dn->dn_datablkshift;
 391                 nblks = (P2ROUNDUP(offset+length, 1ULL<<blkshift) -
 392                     P2ALIGN(offset, 1ULL<<blkshift)) >> blkshift;
 393         } else {
 394                 if (offset + length > dn->dn_datablksz) {
 395                         zfs_panic_recover("zfs: accessing past end of object "
 396                             "%llx/%llx (size=%u access=%llu+%llu)",
 397                             (longlong_t)dn->dn_objset->
 398                             os_dsl_dataset->ds_object,
 399                             (longlong_t)dn->dn_object, dn->dn_datablksz,
 400                             (longlong_t)offset, (longlong_t)length);
 401                         rw_exit(&dn->dn_struct_rwlock);
 402                         return (SET_ERROR(EIO));
 403                 }
 404                 nblks = 1;
 405         }
 406         dbp = kmem_zalloc(sizeof (dmu_buf_t *) * nblks, KM_SLEEP);
 407 
 408         if (dn->dn_objset->os_dsl_dataset)
 409                 dp = dn->dn_objset->os_dsl_dataset->ds_dir->dd_pool;
 410         start = gethrtime();
 411         zio = zio_root(dn->dn_objset->os_spa, NULL, NULL, ZIO_FLAG_CANFAIL);
 412         blkid = dbuf_whichblock(dn, offset);
 413         for (i = 0; i < nblks; i++) {
 414                 dmu_buf_impl_t *db = dbuf_hold(dn, blkid+i, tag);
 415                 if (db == NULL) {
 416                         rw_exit(&dn->dn_struct_rwlock);
 417                         dmu_buf_rele_array(dbp, nblks, tag);
 418                         zio_nowait(zio);
 419                         return (SET_ERROR(EIO));
 420                 }
 421                 /* initiate async i/o */
 422                 if (read) {
 423                         (void) dbuf_read(db, zio, dbuf_flags);
 424                 }
 425                 dbp[i] = &db->db;
 426         }
 427         rw_exit(&dn->dn_struct_rwlock);
 428 
 429         /* wait for async i/o */
 430         err = zio_wait(zio);
 431         /* track read overhead when we are in sync context */
 432         if (dp && dsl_pool_sync_context(dp))
 433                 dp->dp_read_overhead += gethrtime() - start;
 434         if (err) {
 435                 dmu_buf_rele_array(dbp, nblks, tag);
 436                 return (err);
 437         }
 438 
 439         /* wait for other io to complete */
 440         if (read) {
 441                 for (i = 0; i < nblks; i++) {
 442                         dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbp[i];
 443                         mutex_enter(&db->db_mtx);
 444                         while (db->db_state == DB_READ ||
 445                             db->db_state == DB_FILL)
 446                                 cv_wait(&db->db_changed, &db->db_mtx);
 447                         if (db->db_state == DB_UNCACHED)
 448                                 err = SET_ERROR(EIO);
 449                         mutex_exit(&db->db_mtx);
 450                         if (err) {
 451                                 dmu_buf_rele_array(dbp, nblks, tag);
 452                                 return (err);
 453                         }
 454                 }
 455         }
 456 
 457         *numbufsp = nblks;
 458         *dbpp = dbp;
 459         return (0);
 460 }
 461 
 462 static int
 463 dmu_buf_hold_array(objset_t *os, uint64_t object, uint64_t offset,
 464     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
 465 {
 466         dnode_t *dn;
 467         int err;
 468 
 469         err = dnode_hold(os, object, FTAG, &dn);
 470         if (err)
 471                 return (err);
 472 
 473         err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
 474             numbufsp, dbpp, DMU_READ_PREFETCH);
 475 
 476         dnode_rele(dn, FTAG);
 477 
 478         return (err);
 479 }
 480 
 481 int
 482 dmu_buf_hold_array_by_bonus(dmu_buf_t *db_fake, uint64_t offset,
 483     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
 484 {
 485         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
 486         dnode_t *dn;
 487         int err;
 488 
 489         DB_DNODE_ENTER(db);
 490         dn = DB_DNODE(db);
 491         err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
 492             numbufsp, dbpp, DMU_READ_PREFETCH);
 493         DB_DNODE_EXIT(db);
 494 
 495         return (err);
 496 }
 497 
 498 void
 499 dmu_buf_rele_array(dmu_buf_t **dbp_fake, int numbufs, void *tag)
 500 {
 501         int i;
 502         dmu_buf_impl_t **dbp = (dmu_buf_impl_t **)dbp_fake;
 503 
 504         if (numbufs == 0)
 505                 return;
 506 
 507         for (i = 0; i < numbufs; i++) {
 508                 if (dbp[i])
 509                         dbuf_rele(dbp[i], tag);
 510         }
 511 
 512         kmem_free(dbp, sizeof (dmu_buf_t *) * numbufs);
 513 }
 514 
 515 void
 516 dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset, uint64_t len)
 517 {
 518         dnode_t *dn;
 519         uint64_t blkid;
 520         int nblks, i, err;
 521 
 522         if (zfs_prefetch_disable)
 523                 return;
 524 
 525         if (len == 0) {  /* they're interested in the bonus buffer */
 526                 dn = DMU_META_DNODE(os);
 527 
 528                 if (object == 0 || object >= DN_MAX_OBJECT)
 529                         return;
 530 
 531                 rw_enter(&dn->dn_struct_rwlock, RW_READER);
 532                 blkid = dbuf_whichblock(dn, object * sizeof (dnode_phys_t));
 533                 dbuf_prefetch(dn, blkid);
 534                 rw_exit(&dn->dn_struct_rwlock);
 535                 return;
 536         }
 537 
 538         /*
 539          * XXX - Note, if the dnode for the requested object is not
 540          * already cached, we will do a *synchronous* read in the
 541          * dnode_hold() call.  The same is true for any indirects.
 542          */
 543         err = dnode_hold(os, object, FTAG, &dn);
 544         if (err != 0)
 545                 return;
 546 
 547         rw_enter(&dn->dn_struct_rwlock, RW_READER);
 548         if (dn->dn_datablkshift) {
 549                 int blkshift = dn->dn_datablkshift;
 550                 nblks = (P2ROUNDUP(offset+len, 1<<blkshift) -
 551                     P2ALIGN(offset, 1<<blkshift)) >> blkshift;
 552         } else {
 553                 nblks = (offset < dn->dn_datablksz);
 554         }
 555 
 556         if (nblks != 0) {
 557                 blkid = dbuf_whichblock(dn, offset);
 558                 for (i = 0; i < nblks; i++)
 559                         dbuf_prefetch(dn, blkid+i);
 560         }
 561 
 562         rw_exit(&dn->dn_struct_rwlock);
 563 
 564         dnode_rele(dn, FTAG);
 565 }
 566 
 567 /*
 568  * Get the next "chunk" of file data to free.  We traverse the file from
 569  * the end so that the file gets shorter over time (if we crashes in the
 570  * middle, this will leave us in a better state).  We find allocated file
 571  * data by simply searching the allocated level 1 indirects.
 572  */
 573 static int
 574 get_next_chunk(dnode_t *dn, uint64_t *start, uint64_t limit)
 575 {
 576         uint64_t len = *start - limit;
 577         uint64_t blkcnt = 0;
 578         uint64_t maxblks = DMU_MAX_ACCESS / (1ULL << (dn->dn_indblkshift + 1));
 579         uint64_t iblkrange =
 580             dn->dn_datablksz * EPB(dn->dn_indblkshift, SPA_BLKPTRSHIFT);
 581 
 582         ASSERT(limit <= *start);
 583 
 584         if (len <= iblkrange * maxblks) {
 585                 *start = limit;
 586                 return (0);
 587         }
 588         ASSERT(ISP2(iblkrange));
 589 
 590         while (*start > limit && blkcnt < maxblks) {
 591                 int err;
 592 
 593                 /* find next allocated L1 indirect */
 594                 err = dnode_next_offset(dn,
 595                     DNODE_FIND_BACKWARDS, start, 2, 1, 0);
 596 
 597                 /* if there are no more, then we are done */
 598                 if (err == ESRCH) {
 599                         *start = limit;
 600                         return (0);
 601                 } else if (err) {
 602                         return (err);
 603                 }
 604                 blkcnt += 1;
 605 
 606                 /* reset offset to end of "next" block back */
 607                 *start = P2ALIGN(*start, iblkrange);
 608                 if (*start <= limit)
 609                         *start = limit;
 610                 else
 611                         *start -= 1;
 612         }
 613         return (0);
 614 }
 615 
 616 static int
 617 dmu_free_long_range_impl(objset_t *os, dnode_t *dn, uint64_t offset,
 618     uint64_t length, boolean_t free_dnode)
 619 {
 620         dmu_tx_t *tx;
 621         uint64_t object_size, start, end, len;
 622         boolean_t trunc = (length == DMU_OBJECT_END);
 623         int align, err;
 624 
 625         align = 1 << dn->dn_datablkshift;
 626         ASSERT(align > 0);
 627         object_size = align == 1 ? dn->dn_datablksz :
 628             (dn->dn_maxblkid + 1) << dn->dn_datablkshift;
 629 
 630         end = offset + length;
 631         if (trunc || end > object_size)
 632                 end = object_size;
 633         if (end <= offset)
 634                 return (0);
 635         length = end - offset;
 636 
 637         while (length) {
 638                 start = end;
 639                 /* assert(offset <= start) */
 640                 err = get_next_chunk(dn, &start, offset);
 641                 if (err)
 642                         return (err);
 643                 len = trunc ? DMU_OBJECT_END : end - start;
 644 
 645                 tx = dmu_tx_create(os);
 646                 dmu_tx_hold_free(tx, dn->dn_object, start, len);
 647                 err = dmu_tx_assign(tx, TXG_WAIT);
 648                 if (err) {
 649                         dmu_tx_abort(tx);
 650                         return (err);
 651                 }
 652 
 653                 dnode_free_range(dn, start, trunc ? -1 : len, tx);
 654 
 655                 if (start == 0 && free_dnode) {
 656                         ASSERT(trunc);
 657                         dnode_free(dn, tx);
 658                 }
 659 
 660                 length -= end - start;
 661 
 662                 dmu_tx_commit(tx);
 663                 end = start;
 664         }
 665         return (0);
 666 }
 667 
 668 int
 669 dmu_free_long_range(objset_t *os, uint64_t object,
 670     uint64_t offset, uint64_t length)
 671 {
 672         dnode_t *dn;
 673         int err;
 674 
 675         err = dnode_hold(os, object, FTAG, &dn);
 676         if (err != 0)
 677                 return (err);
 678         err = dmu_free_long_range_impl(os, dn, offset, length, FALSE);
 679         dnode_rele(dn, FTAG);
 680         return (err);
 681 }
 682 
 683 int
 684 dmu_free_object(objset_t *os, uint64_t object)
 685 {
 686         dnode_t *dn;
 687         dmu_tx_t *tx;
 688         int err;
 689 
 690         err = dnode_hold_impl(os, object, DNODE_MUST_BE_ALLOCATED,
 691             FTAG, &dn);
 692         if (err != 0)
 693                 return (err);
 694         if (dn->dn_nlevels == 1) {
 695                 tx = dmu_tx_create(os);
 696                 dmu_tx_hold_bonus(tx, object);
 697                 dmu_tx_hold_free(tx, dn->dn_object, 0, DMU_OBJECT_END);
 698                 err = dmu_tx_assign(tx, TXG_WAIT);
 699                 if (err == 0) {
 700                         dnode_free_range(dn, 0, DMU_OBJECT_END, tx);
 701                         dnode_free(dn, tx);
 702                         dmu_tx_commit(tx);
 703                 } else {
 704                         dmu_tx_abort(tx);
 705                 }
 706         } else {
 707                 err = dmu_free_long_range_impl(os, dn, 0, DMU_OBJECT_END, TRUE);
 708         }
 709         dnode_rele(dn, FTAG);
 710         return (err);
 711 }
 712 
 713 int
 714 dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
 715     uint64_t size, dmu_tx_t *tx)
 716 {
 717         dnode_t *dn;
 718         int err = dnode_hold(os, object, FTAG, &dn);
 719         if (err)
 720                 return (err);
 721         ASSERT(offset < UINT64_MAX);
 722         ASSERT(size == -1ULL || size <= UINT64_MAX - offset);
 723         dnode_free_range(dn, offset, size, tx);
 724         dnode_rele(dn, FTAG);
 725         return (0);
 726 }
 727 
 728 int
 729 dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 730     void *buf, uint32_t flags)
 731 {
 732         dnode_t *dn;
 733         dmu_buf_t **dbp;
 734         int numbufs, err;
 735 
 736         err = dnode_hold(os, object, FTAG, &dn);
 737         if (err)
 738                 return (err);
 739 
 740         /*
 741          * Deal with odd block sizes, where there can't be data past the first
 742          * block.  If we ever do the tail block optimization, we will need to
 743          * handle that here as well.
 744          */
 745         if (dn->dn_maxblkid == 0) {
 746                 int newsz = offset > dn->dn_datablksz ? 0 :
 747                     MIN(size, dn->dn_datablksz - offset);
 748                 bzero((char *)buf + newsz, size - newsz);
 749                 size = newsz;
 750         }
 751 
 752         while (size > 0) {
 753                 uint64_t mylen = MIN(size, DMU_MAX_ACCESS / 2);
 754                 int i;
 755 
 756                 /*
 757                  * NB: we could do this block-at-a-time, but it's nice
 758                  * to be reading in parallel.
 759                  */
 760                 err = dmu_buf_hold_array_by_dnode(dn, offset, mylen,
 761                     TRUE, FTAG, &numbufs, &dbp, flags);
 762                 if (err)
 763                         break;
 764 
 765                 for (i = 0; i < numbufs; i++) {
 766                         int tocpy;
 767                         int bufoff;
 768                         dmu_buf_t *db = dbp[i];
 769 
 770                         ASSERT(size > 0);
 771 
 772                         bufoff = offset - db->db_offset;
 773                         tocpy = (int)MIN(db->db_size - bufoff, size);
 774 
 775                         bcopy((char *)db->db_data + bufoff, buf, tocpy);
 776 
 777                         offset += tocpy;
 778                         size -= tocpy;
 779                         buf = (char *)buf + tocpy;
 780                 }
 781                 dmu_buf_rele_array(dbp, numbufs, FTAG);
 782         }
 783         dnode_rele(dn, FTAG);
 784         return (err);
 785 }
 786 
 787 void
 788 dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 789     const void *buf, dmu_tx_t *tx)
 790 {
 791         dmu_buf_t **dbp;
 792         int numbufs, i;
 793 
 794         if (size == 0)
 795                 return;
 796 
 797         VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
 798             FALSE, FTAG, &numbufs, &dbp));
 799 
 800         for (i = 0; i < numbufs; i++) {
 801                 int tocpy;
 802                 int bufoff;
 803                 dmu_buf_t *db = dbp[i];
 804 
 805                 ASSERT(size > 0);
 806 
 807                 bufoff = offset - db->db_offset;
 808                 tocpy = (int)MIN(db->db_size - bufoff, size);
 809 
 810                 ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
 811 
 812                 if (tocpy == db->db_size)
 813                         dmu_buf_will_fill(db, tx);
 814                 else
 815                         dmu_buf_will_dirty(db, tx);
 816 
 817                 bcopy(buf, (char *)db->db_data + bufoff, tocpy);
 818 
 819                 if (tocpy == db->db_size)
 820                         dmu_buf_fill_done(db, tx);
 821 
 822                 offset += tocpy;
 823                 size -= tocpy;
 824                 buf = (char *)buf + tocpy;
 825         }
 826         dmu_buf_rele_array(dbp, numbufs, FTAG);
 827 }
 828 
 829 void
 830 dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 831     dmu_tx_t *tx)
 832 {
 833         dmu_buf_t **dbp;
 834         int numbufs, i;
 835 
 836         if (size == 0)
 837                 return;
 838 
 839         VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
 840             FALSE, FTAG, &numbufs, &dbp));
 841 
 842         for (i = 0; i < numbufs; i++) {
 843                 dmu_buf_t *db = dbp[i];
 844 
 845                 dmu_buf_will_not_fill(db, tx);
 846         }
 847         dmu_buf_rele_array(dbp, numbufs, FTAG);
 848 }
 849 
 850 /*
 851  * DMU support for xuio
 852  */
 853 kstat_t *xuio_ksp = NULL;
 854 
 855 int
 856 dmu_xuio_init(xuio_t *xuio, int nblk)
 857 {
 858         dmu_xuio_t *priv;
 859         uio_t *uio = &xuio->xu_uio;
 860 
 861         uio->uio_iovcnt = nblk;
 862         uio->uio_iov = kmem_zalloc(nblk * sizeof (iovec_t), KM_SLEEP);
 863 
 864         priv = kmem_zalloc(sizeof (dmu_xuio_t), KM_SLEEP);
 865         priv->cnt = nblk;
 866         priv->bufs = kmem_zalloc(nblk * sizeof (arc_buf_t *), KM_SLEEP);
 867         priv->iovp = uio->uio_iov;
 868         XUIO_XUZC_PRIV(xuio) = priv;
 869 
 870         if (XUIO_XUZC_RW(xuio) == UIO_READ)
 871                 XUIOSTAT_INCR(xuiostat_onloan_rbuf, nblk);
 872         else
 873                 XUIOSTAT_INCR(xuiostat_onloan_wbuf, nblk);
 874 
 875         return (0);
 876 }
 877 
 878 void
 879 dmu_xuio_fini(xuio_t *xuio)
 880 {
 881         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 882         int nblk = priv->cnt;
 883 
 884         kmem_free(priv->iovp, nblk * sizeof (iovec_t));
 885         kmem_free(priv->bufs, nblk * sizeof (arc_buf_t *));
 886         kmem_free(priv, sizeof (dmu_xuio_t));
 887 
 888         if (XUIO_XUZC_RW(xuio) == UIO_READ)
 889                 XUIOSTAT_INCR(xuiostat_onloan_rbuf, -nblk);
 890         else
 891                 XUIOSTAT_INCR(xuiostat_onloan_wbuf, -nblk);
 892 }
 893 
 894 /*
 895  * Initialize iov[priv->next] and priv->bufs[priv->next] with { off, n, abuf }
 896  * and increase priv->next by 1.
 897  */
 898 int
 899 dmu_xuio_add(xuio_t *xuio, arc_buf_t *abuf, offset_t off, size_t n)
 900 {
 901         struct iovec *iov;
 902         uio_t *uio = &xuio->xu_uio;
 903         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 904         int i = priv->next++;
 905 
 906         ASSERT(i < priv->cnt);
 907         ASSERT(off + n <= arc_buf_size(abuf));
 908         iov = uio->uio_iov + i;
 909         iov->iov_base = (char *)abuf->b_data + off;
 910         iov->iov_len = n;
 911         priv->bufs[i] = abuf;
 912         return (0);
 913 }
 914 
 915 int
 916 dmu_xuio_cnt(xuio_t *xuio)
 917 {
 918         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 919         return (priv->cnt);
 920 }
 921 
 922 arc_buf_t *
 923 dmu_xuio_arcbuf(xuio_t *xuio, int i)
 924 {
 925         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 926 
 927         ASSERT(i < priv->cnt);
 928         return (priv->bufs[i]);
 929 }
 930 
 931 void
 932 dmu_xuio_clear(xuio_t *xuio, int i)
 933 {
 934         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 935 
 936         ASSERT(i < priv->cnt);
 937         priv->bufs[i] = NULL;
 938 }
 939 
 940 static void
 941 xuio_stat_init(void)
 942 {
 943         xuio_ksp = kstat_create("zfs", 0, "xuio_stats", "misc",
 944             KSTAT_TYPE_NAMED, sizeof (xuio_stats) / sizeof (kstat_named_t),
 945             KSTAT_FLAG_VIRTUAL);
 946         if (xuio_ksp != NULL) {
 947                 xuio_ksp->ks_data = &xuio_stats;
 948                 kstat_install(xuio_ksp);
 949         }
 950 }
 951 
 952 static void
 953 xuio_stat_fini(void)
 954 {
 955         if (xuio_ksp != NULL) {
 956                 kstat_delete(xuio_ksp);
 957                 xuio_ksp = NULL;
 958         }
 959 }
 960 
 961 void
 962 xuio_stat_wbuf_copied()
 963 {
 964         XUIOSTAT_BUMP(xuiostat_wbuf_copied);
 965 }
 966 
 967 void
 968 xuio_stat_wbuf_nocopy()
 969 {
 970         XUIOSTAT_BUMP(xuiostat_wbuf_nocopy);
 971 }
 972 
 973 #ifdef _KERNEL
 974 int
 975 dmu_read_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size)
 976 {
 977         dmu_buf_t **dbp;
 978         int numbufs, i, err;
 979         xuio_t *xuio = NULL;
 980 
 981         /*
 982          * NB: we could do this block-at-a-time, but it's nice
 983          * to be reading in parallel.
 984          */
 985         err = dmu_buf_hold_array(os, object, uio->uio_loffset, size, TRUE, FTAG,
 986             &numbufs, &dbp);
 987         if (err)
 988                 return (err);
 989 
 990         if (uio->uio_extflg == UIO_XUIO)
 991                 xuio = (xuio_t *)uio;
 992 
 993         for (i = 0; i < numbufs; i++) {
 994                 int tocpy;
 995                 int bufoff;
 996                 dmu_buf_t *db = dbp[i];
 997 
 998                 ASSERT(size > 0);
 999 
1000                 bufoff = uio->uio_loffset - db->db_offset;
1001                 tocpy = (int)MIN(db->db_size - bufoff, size);
1002 
1003                 if (xuio) {
1004                         dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
1005                         arc_buf_t *dbuf_abuf = dbi->db_buf;
1006                         arc_buf_t *abuf = dbuf_loan_arcbuf(dbi);
1007                         err = dmu_xuio_add(xuio, abuf, bufoff, tocpy);
1008                         if (!err) {
1009                                 uio->uio_resid -= tocpy;
1010                                 uio->uio_loffset += tocpy;
1011                         }
1012 
1013                         if (abuf == dbuf_abuf)
1014                                 XUIOSTAT_BUMP(xuiostat_rbuf_nocopy);
1015                         else
1016                                 XUIOSTAT_BUMP(xuiostat_rbuf_copied);
1017                 } else {
1018                         err = uiomove((char *)db->db_data + bufoff, tocpy,
1019                             UIO_READ, uio);
1020                 }
1021                 if (err)
1022                         break;
1023 
1024                 size -= tocpy;
1025         }
1026         dmu_buf_rele_array(dbp, numbufs, FTAG);
1027 
1028         return (err);
1029 }
1030 
1031 static int
1032 dmu_write_uio_dnode(dnode_t *dn, uio_t *uio, uint64_t size, dmu_tx_t *tx)
1033 {
1034         dmu_buf_t **dbp;
1035         int numbufs;
1036         int err = 0;
1037         int i;
1038 
1039         err = dmu_buf_hold_array_by_dnode(dn, uio->uio_loffset, size,
1040             FALSE, FTAG, &numbufs, &dbp, DMU_READ_PREFETCH);
1041         if (err)
1042                 return (err);
1043 
1044         for (i = 0; i < numbufs; i++) {
1045                 int tocpy;
1046                 int bufoff;
1047                 dmu_buf_t *db = dbp[i];
1048 
1049                 ASSERT(size > 0);
1050 
1051                 bufoff = uio->uio_loffset - db->db_offset;
1052                 tocpy = (int)MIN(db->db_size - bufoff, size);
1053 
1054                 ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
1055 
1056                 if (tocpy == db->db_size)
1057                         dmu_buf_will_fill(db, tx);
1058                 else
1059                         dmu_buf_will_dirty(db, tx);
1060 
1061                 /*
1062                  * XXX uiomove could block forever (eg. nfs-backed
1063                  * pages).  There needs to be a uiolockdown() function
1064                  * to lock the pages in memory, so that uiomove won't
1065                  * block.
1066                  */
1067                 err = uiomove((char *)db->db_data + bufoff, tocpy,
1068                     UIO_WRITE, uio);
1069 
1070                 if (tocpy == db->db_size)
1071                         dmu_buf_fill_done(db, tx);
1072 
1073                 if (err)
1074                         break;
1075 
1076                 size -= tocpy;
1077         }
1078 
1079         dmu_buf_rele_array(dbp, numbufs, FTAG);
1080         return (err);
1081 }
1082 
1083 int
1084 dmu_write_uio_dbuf(dmu_buf_t *zdb, uio_t *uio, uint64_t size,
1085     dmu_tx_t *tx)
1086 {
1087         dmu_buf_impl_t *db = (dmu_buf_impl_t *)zdb;
1088         dnode_t *dn;
1089         int err;
1090 
1091         if (size == 0)
1092                 return (0);
1093 
1094         DB_DNODE_ENTER(db);
1095         dn = DB_DNODE(db);
1096         err = dmu_write_uio_dnode(dn, uio, size, tx);
1097         DB_DNODE_EXIT(db);
1098 
1099         return (err);
1100 }
1101 
1102 int
1103 dmu_write_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size,
1104     dmu_tx_t *tx)
1105 {
1106         dnode_t *dn;
1107         int err;
1108 
1109         if (size == 0)
1110                 return (0);
1111 
1112         err = dnode_hold(os, object, FTAG, &dn);
1113         if (err)
1114                 return (err);
1115 
1116         err = dmu_write_uio_dnode(dn, uio, size, tx);
1117 
1118         dnode_rele(dn, FTAG);
1119 
1120         return (err);
1121 }
1122 
1123 int
1124 dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
1125     page_t *pp, dmu_tx_t *tx)
1126 {
1127         dmu_buf_t **dbp;
1128         int numbufs, i;
1129         int err;
1130 
1131         if (size == 0)
1132                 return (0);
1133 
1134         err = dmu_buf_hold_array(os, object, offset, size,
1135             FALSE, FTAG, &numbufs, &dbp);
1136         if (err)
1137                 return (err);
1138 
1139         for (i = 0; i < numbufs; i++) {
1140                 int tocpy, copied, thiscpy;
1141                 int bufoff;
1142                 dmu_buf_t *db = dbp[i];
1143                 caddr_t va;
1144 
1145                 ASSERT(size > 0);
1146                 ASSERT3U(db->db_size, >=, PAGESIZE);
1147 
1148                 bufoff = offset - db->db_offset;
1149                 tocpy = (int)MIN(db->db_size - bufoff, size);
1150 
1151                 ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
1152 
1153                 if (tocpy == db->db_size)
1154                         dmu_buf_will_fill(db, tx);
1155                 else
1156                         dmu_buf_will_dirty(db, tx);
1157 
1158                 for (copied = 0; copied < tocpy; copied += PAGESIZE) {
1159                         ASSERT3U(pp->p_offset, ==, db->db_offset + bufoff);
1160                         thiscpy = MIN(PAGESIZE, tocpy - copied);
1161                         va = zfs_map_page(pp, S_READ);
1162                         bcopy(va, (char *)db->db_data + bufoff, thiscpy);
1163                         zfs_unmap_page(pp, va);
1164                         pp = pp->p_next;
1165                         bufoff += PAGESIZE;
1166                 }
1167 
1168                 if (tocpy == db->db_size)
1169                         dmu_buf_fill_done(db, tx);
1170 
1171                 offset += tocpy;
1172                 size -= tocpy;
1173         }
1174         dmu_buf_rele_array(dbp, numbufs, FTAG);
1175         return (err);
1176 }
1177 #endif
1178 
1179 /*
1180  * Allocate a loaned anonymous arc buffer.
1181  */
1182 arc_buf_t *
1183 dmu_request_arcbuf(dmu_buf_t *handle, int size)
1184 {
1185         dmu_buf_impl_t *db = (dmu_buf_impl_t *)handle;
1186         spa_t *spa;
1187 
1188         DB_GET_SPA(&spa, db);
1189         return (arc_loan_buf(spa, size));
1190 }
1191 
1192 /*
1193  * Free a loaned arc buffer.
1194  */
1195 void
1196 dmu_return_arcbuf(arc_buf_t *buf)
1197 {
1198         arc_return_buf(buf, FTAG);
1199         VERIFY(arc_buf_remove_ref(buf, FTAG));
1200 }
1201 
1202 /*
1203  * When possible directly assign passed loaned arc buffer to a dbuf.
1204  * If this is not possible copy the contents of passed arc buf via
1205  * dmu_write().
1206  */
1207 void
1208 dmu_assign_arcbuf(dmu_buf_t *handle, uint64_t offset, arc_buf_t *buf,
1209     dmu_tx_t *tx)
1210 {
1211         dmu_buf_impl_t *dbuf = (dmu_buf_impl_t *)handle;
1212         dnode_t *dn;
1213         dmu_buf_impl_t *db;
1214         uint32_t blksz = (uint32_t)arc_buf_size(buf);
1215         uint64_t blkid;
1216 
1217         DB_DNODE_ENTER(dbuf);
1218         dn = DB_DNODE(dbuf);
1219         rw_enter(&dn->dn_struct_rwlock, RW_READER);
1220         blkid = dbuf_whichblock(dn, offset);
1221         VERIFY((db = dbuf_hold(dn, blkid, FTAG)) != NULL);
1222         rw_exit(&dn->dn_struct_rwlock);
1223         DB_DNODE_EXIT(dbuf);
1224 
1225         if (offset == db->db.db_offset && blksz == db->db.db_size) {
1226                 dbuf_assign_arcbuf(db, buf, tx);
1227                 dbuf_rele(db, FTAG);
1228         } else {
1229                 objset_t *os;
1230                 uint64_t object;
1231 
1232                 DB_DNODE_ENTER(dbuf);
1233                 dn = DB_DNODE(dbuf);
1234                 os = dn->dn_objset;
1235                 object = dn->dn_object;
1236                 DB_DNODE_EXIT(dbuf);
1237 
1238                 dbuf_rele(db, FTAG);
1239                 dmu_write(os, object, offset, blksz, buf->b_data, tx);
1240                 dmu_return_arcbuf(buf);
1241                 XUIOSTAT_BUMP(xuiostat_wbuf_copied);
1242         }
1243 }
1244 
1245 typedef struct {
1246         dbuf_dirty_record_t     *dsa_dr;
1247         dmu_sync_cb_t           *dsa_done;
1248         zgd_t                   *dsa_zgd;
1249         dmu_tx_t                *dsa_tx;
1250 } dmu_sync_arg_t;
1251 
1252 /* ARGSUSED */
1253 static void
1254 dmu_sync_ready(zio_t *zio, arc_buf_t *buf, void *varg)
1255 {
1256         dmu_sync_arg_t *dsa = varg;
1257         dmu_buf_t *db = dsa->dsa_zgd->zgd_db;
1258         blkptr_t *bp = zio->io_bp;
1259 
1260         if (zio->io_error == 0) {
1261                 if (BP_IS_HOLE(bp)) {
1262                         /*
1263                          * A block of zeros may compress to a hole, but the
1264                          * block size still needs to be known for replay.
1265                          */
1266                         BP_SET_LSIZE(bp, db->db_size);
1267                 } else {
1268                         ASSERT(BP_GET_LEVEL(bp) == 0);
1269                         bp->blk_fill = 1;
1270                 }
1271         }
1272 }
1273 
1274 static void
1275 dmu_sync_late_arrival_ready(zio_t *zio)
1276 {
1277         dmu_sync_ready(zio, NULL, zio->io_private);
1278 }
1279 
1280 /* ARGSUSED */
1281 static void
1282 dmu_sync_done(zio_t *zio, arc_buf_t *buf, void *varg)
1283 {
1284         dmu_sync_arg_t *dsa = varg;
1285         dbuf_dirty_record_t *dr = dsa->dsa_dr;
1286         dmu_buf_impl_t *db = dr->dr_dbuf;
1287 
1288         mutex_enter(&db->db_mtx);
1289         ASSERT(dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC);
1290         if (zio->io_error == 0) {
1291                 dr->dt.dl.dr_nopwrite = !!(zio->io_flags & ZIO_FLAG_NOPWRITE);
1292                 if (dr->dt.dl.dr_nopwrite) {
1293                         blkptr_t *bp = zio->io_bp;
1294                         blkptr_t *bp_orig = &zio->io_bp_orig;
1295                         uint8_t chksum = BP_GET_CHECKSUM(bp_orig);
1296 
1297                         ASSERT(BP_EQUAL(bp, bp_orig));
1298                         ASSERT(zio->io_prop.zp_compress != ZIO_COMPRESS_OFF);
1299                         ASSERT(zio_checksum_table[chksum].ci_dedup);
1300                 }
1301                 dr->dt.dl.dr_overridden_by = *zio->io_bp;
1302                 dr->dt.dl.dr_override_state = DR_OVERRIDDEN;
1303                 dr->dt.dl.dr_copies = zio->io_prop.zp_copies;
1304                 if (BP_IS_HOLE(&dr->dt.dl.dr_overridden_by))
1305                         BP_ZERO(&dr->dt.dl.dr_overridden_by);
1306         } else {
1307                 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
1308         }
1309         cv_broadcast(&db->db_changed);
1310         mutex_exit(&db->db_mtx);
1311 
1312         dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
1313 
1314         kmem_free(dsa, sizeof (*dsa));
1315 }
1316 
1317 static void
1318 dmu_sync_late_arrival_done(zio_t *zio)
1319 {
1320         blkptr_t *bp = zio->io_bp;
1321         dmu_sync_arg_t *dsa = zio->io_private;
1322         blkptr_t *bp_orig = &zio->io_bp_orig;
1323 
1324         if (zio->io_error == 0 && !BP_IS_HOLE(bp)) {
1325                 /*
1326                  * If we didn't allocate a new block (i.e. ZIO_FLAG_NOPWRITE)
1327                  * then there is nothing to do here. Otherwise, free the
1328                  * newly allocated block in this txg.
1329                  */
1330                 if (zio->io_flags & ZIO_FLAG_NOPWRITE) {
1331                         ASSERT(BP_EQUAL(bp, bp_orig));
1332                 } else {
1333                         ASSERT(BP_IS_HOLE(bp_orig) || !BP_EQUAL(bp, bp_orig));
1334                         ASSERT(zio->io_bp->blk_birth == zio->io_txg);
1335                         ASSERT(zio->io_txg > spa_syncing_txg(zio->io_spa));
1336                         zio_free(zio->io_spa, zio->io_txg, zio->io_bp);
1337                 }
1338         }
1339 
1340         dmu_tx_commit(dsa->dsa_tx);
1341 
1342         dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
1343 
1344         kmem_free(dsa, sizeof (*dsa));
1345 }
1346 
1347 static int
1348 dmu_sync_late_arrival(zio_t *pio, objset_t *os, dmu_sync_cb_t *done, zgd_t *zgd,
1349     zio_prop_t *zp, zbookmark_t *zb)
1350 {
1351         dmu_sync_arg_t *dsa;
1352         dmu_tx_t *tx;
1353 
1354         tx = dmu_tx_create(os);
1355         dmu_tx_hold_space(tx, zgd->zgd_db->db_size);
1356         if (dmu_tx_assign(tx, TXG_WAIT) != 0) {
1357                 dmu_tx_abort(tx);
1358                 /* Make zl_get_data do txg_waited_synced() */
1359                 return (SET_ERROR(EIO));
1360         }
1361 
1362         dsa = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
1363         dsa->dsa_dr = NULL;
1364         dsa->dsa_done = done;
1365         dsa->dsa_zgd = zgd;
1366         dsa->dsa_tx = tx;
1367 
1368         zio_nowait(zio_write(pio, os->os_spa, dmu_tx_get_txg(tx), zgd->zgd_bp,
1369             zgd->zgd_db->db_data, zgd->zgd_db->db_size, zp,
1370             dmu_sync_late_arrival_ready, dmu_sync_late_arrival_done, dsa,
1371             ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_CANFAIL, zb));
1372 
1373         return (0);
1374 }
1375 
1376 /*
1377  * Intent log support: sync the block associated with db to disk.
1378  * N.B. and XXX: the caller is responsible for making sure that the
1379  * data isn't changing while dmu_sync() is writing it.
1380  *
1381  * Return values:
1382  *
1383  *      EEXIST: this txg has already been synced, so there's nothing to do.
1384  *              The caller should not log the write.
1385  *
1386  *      ENOENT: the block was dbuf_free_range()'d, so there's nothing to do.
1387  *              The caller should not log the write.
1388  *
1389  *      EALREADY: this block is already in the process of being synced.
1390  *              The caller should track its progress (somehow).
1391  *
1392  *      EIO: could not do the I/O.
1393  *              The caller should do a txg_wait_synced().
1394  *
1395  *      0: the I/O has been initiated.
1396  *              The caller should log this blkptr in the done callback.
1397  *              It is possible that the I/O will fail, in which case
1398  *              the error will be reported to the done callback and
1399  *              propagated to pio from zio_done().
1400  */
1401 int
1402 dmu_sync(zio_t *pio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd)
1403 {
1404         blkptr_t *bp = zgd->zgd_bp;
1405         dmu_buf_impl_t *db = (dmu_buf_impl_t *)zgd->zgd_db;
1406         objset_t *os = db->db_objset;
1407         dsl_dataset_t *ds = os->os_dsl_dataset;
1408         dbuf_dirty_record_t *dr;
1409         dmu_sync_arg_t *dsa;
1410         zbookmark_t zb;
1411         zio_prop_t zp;
1412         dnode_t *dn;
1413 
1414         ASSERT(pio != NULL);
1415         ASSERT(txg != 0);
1416 
1417         SET_BOOKMARK(&zb, ds->ds_object,
1418             db->db.db_object, db->db_level, db->db_blkid);
1419 
1420         DB_DNODE_ENTER(db);
1421         dn = DB_DNODE(db);
1422         dmu_write_policy(os, dn, db->db_level, WP_DMU_SYNC, &zp, txg);
1423         DB_DNODE_EXIT(db);
1424 
1425         /*
1426          * If we're frozen (running ziltest), we always need to generate a bp.
1427          */
1428         if (txg > spa_freeze_txg(os->os_spa))
1429                 return (dmu_sync_late_arrival(pio, os, done, zgd, &zp, &zb));
1430 
1431         /*
1432          * Grabbing db_mtx now provides a barrier between dbuf_sync_leaf()
1433          * and us.  If we determine that this txg is not yet syncing,
1434          * but it begins to sync a moment later, that's OK because the
1435          * sync thread will block in dbuf_sync_leaf() until we drop db_mtx.
1436          */
1437         mutex_enter(&db->db_mtx);
1438 
1439         if (txg <= spa_last_synced_txg(os->os_spa)) {
1440                 /*
1441                  * This txg has already synced.  There's nothing to do.
1442                  */
1443                 mutex_exit(&db->db_mtx);
1444                 return (SET_ERROR(EEXIST));
1445         }
1446 
1447         if (txg <= spa_syncing_txg(os->os_spa)) {
1448                 /*
1449                  * This txg is currently syncing, so we can't mess with
1450                  * the dirty record anymore; just write a new log block.
1451                  */
1452                 mutex_exit(&db->db_mtx);
1453                 return (dmu_sync_late_arrival(pio, os, done, zgd, &zp, &zb));
1454         }
1455 
1456         dr = db->db_last_dirty;
1457         while (dr && dr->dr_txg != txg)
1458                 dr = dr->dr_next;
1459 
1460         if (dr == NULL) {
1461                 /*
1462                  * There's no dr for this dbuf, so it must have been freed.
1463                  * There's no need to log writes to freed blocks, so we're done.
1464                  */
1465                 mutex_exit(&db->db_mtx);
1466                 return (SET_ERROR(ENOENT));
1467         }
1468 
1469         ASSERT(dr->dr_next == NULL || dr->dr_next->dr_txg < txg);
1470 
1471         /*
1472          * Assume the on-disk data is X, the current syncing data is Y,
1473          * and the current in-memory data is Z (currently in dmu_sync).
1474          * X and Z are identical but Y is has been modified. Normally,
1475          * when X and Z are the same we will perform a nopwrite but if Y
1476          * is different we must disable nopwrite since the resulting write
1477          * of Y to disk can free the block containing X. If we allowed a
1478          * nopwrite to occur the block pointing to Z would reference a freed
1479          * block. Since this is a rare case we simplify this by disabling
1480          * nopwrite if the current dmu_sync-ing dbuf has been modified in
1481          * a previous transaction.
1482          */
1483         if (dr->dr_next)
1484                 zp.zp_nopwrite = B_FALSE;
1485 
1486         ASSERT(dr->dr_txg == txg);
1487         if (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC ||
1488             dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
1489                 /*
1490                  * We have already issued a sync write for this buffer,
1491                  * or this buffer has already been synced.  It could not
1492                  * have been dirtied since, or we would have cleared the state.
1493                  */
1494                 mutex_exit(&db->db_mtx);
1495                 return (SET_ERROR(EALREADY));
1496         }
1497 
1498         ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
1499         dr->dt.dl.dr_override_state = DR_IN_DMU_SYNC;
1500         mutex_exit(&db->db_mtx);
1501 
1502         dsa = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
1503         dsa->dsa_dr = dr;
1504         dsa->dsa_done = done;
1505         dsa->dsa_zgd = zgd;
1506         dsa->dsa_tx = NULL;
1507 
1508         zio_nowait(arc_write(pio, os->os_spa, txg,
1509             bp, dr->dt.dl.dr_data, DBUF_IS_L2CACHEABLE(db), &zp,
1510             dmu_sync_ready, dmu_sync_done, dsa,
1511             ZIO_PRIORITY_SYNC_WRITE, 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 int zfs_mdcomp_lz4 = 0;
1561 
1562 void
1563 dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp, zio_prop_t *zp,
1564     uint64_t txg)
1565 {
1566         dmu_object_type_t type = dn ? dn->dn_type : DMU_OT_OBJSET;
1567         boolean_t ismd = (level > 0 || DMU_OT_IS_METADATA(type) ||
1568             (wp & WP_SPILL));
1569         enum zio_checksum checksum = os->os_checksum;
1570         enum zio_compress compress = os->os_compress;
1571         enum zio_checksum dedup_checksum = os->os_dedup_checksum;
1572         boolean_t dedup = B_FALSE;
1573         boolean_t nopwrite = B_FALSE;
1574         boolean_t dedup_verify = os->os_dedup_verify;
1575         int copies = os->os_copies;
1576 
1577         /*
1578          * We maintain different write policies for each of the following
1579          * types of data:
1580          *       1. metadata
1581          *       2. preallocated blocks (i.e. level-0 blocks of a dump device)
1582          *       3. all other level 0 blocks
1583          */
1584         if (ismd) {
1585                 /*
1586                  * XXX -- we should design a compression algorithm
1587                  * that specializes in arrays of bps.
1588                  */
1589                 if (zfs_mdcomp_disable)
1590                         compress = ZIO_COMPRESS_EMPTY;
1591                 else if (zfs_mdcomp_lz4 && os->os_spa != NULL) {
1592                         zfeature_info_t *feat = &spa_feature_table
1593                             [SPA_FEATURE_LZ4_COMPRESS];
1594 
1595                         if (spa_feature_is_active(os->os_spa, feat))
1596                                 compress = ZIO_COMPRESS_LZ4;
1597                         else if (spa_feature_is_enabled(os->os_spa, feat)) {
1598                                 dmu_tx_t *tx;
1599 
1600                                 tx = dmu_tx_create_assigned(
1601                                     spa_get_dsl(os->os_spa), txg);
1602                                 spa_feature_incr(os->os_spa, feat, tx);
1603                                 dmu_tx_commit(tx);
1604                                 compress = ZIO_COMPRESS_LZ4;
1605                         } else
1606                                 compress = ZIO_COMPRESS_LZJB;
1607                 } else
1608                         compress = ZIO_COMPRESS_LZJB;
1609 
1610                 /*
1611                  * Metadata always gets checksummed.  If the data
1612                  * checksum is multi-bit correctable, and it's not a
1613                  * ZBT-style checksum, then it's suitable for metadata
1614                  * as well.  Otherwise, the metadata checksum defaults
1615                  * to fletcher4.
1616                  */
1617                 if (zio_checksum_table[checksum].ci_correctable < 1 ||
1618                     zio_checksum_table[checksum].ci_eck)
1619                         checksum = ZIO_CHECKSUM_FLETCHER_4;
1620         } else if (wp & WP_NOFILL) {
1621                 ASSERT(level == 0);
1622 
1623                 /*
1624                  * If we're writing preallocated blocks, we aren't actually
1625                  * writing them so don't set any policy properties.  These
1626                  * blocks are currently only used by an external subsystem
1627                  * outside of zfs (i.e. dump) and not written by the zio
1628                  * pipeline.
1629                  */
1630                 compress = ZIO_COMPRESS_OFF;
1631                 checksum = ZIO_CHECKSUM_OFF;
1632         } else {
1633                 compress = zio_compress_select(dn->dn_compress, compress);
1634 
1635                 checksum = (dedup_checksum == ZIO_CHECKSUM_OFF) ?
1636                     zio_checksum_select(dn->dn_checksum, checksum) :
1637                     dedup_checksum;
1638 
1639                 /*
1640                  * Determine dedup setting.  If we are in dmu_sync(),
1641                  * we won't actually dedup now because that's all
1642                  * done in syncing context; but we do want to use the
1643                  * dedup checkum.  If the checksum is not strong
1644                  * enough to ensure unique signatures, force
1645                  * dedup_verify.
1646                  */
1647                 if (dedup_checksum != ZIO_CHECKSUM_OFF) {
1648                         dedup = (wp & WP_DMU_SYNC) ? B_FALSE : B_TRUE;
1649                         if (!zio_checksum_table[checksum].ci_dedup)
1650                                 dedup_verify = B_TRUE;
1651                 }
1652 
1653                 /*
1654                  * Enable nopwrite if we have a cryptographically secure
1655                  * checksum that has no known collisions (i.e. SHA-256)
1656                  * and compression is enabled.  We don't enable nopwrite if
1657                  * dedup is enabled as the two features are mutually exclusive.
1658                  */
1659                 nopwrite = (!dedup && zio_checksum_table[checksum].ci_dedup &&
1660                     compress != ZIO_COMPRESS_OFF && zfs_nopwrite_enabled);
1661         }
1662 
1663         zp->zp_checksum = checksum;
1664         zp->zp_compress = compress;
1665         zp->zp_type = (wp & WP_SPILL) ? dn->dn_bonustype : type;
1666         zp->zp_level = level;
1667         zp->zp_copies = MIN(copies + ismd, spa_max_replication(os->os_spa));
1668         zp->zp_dedup = dedup;
1669         zp->zp_dedup_verify = dedup && dedup_verify;
1670         zp->zp_nopwrite = nopwrite;
1671 }
1672 
1673 int
1674 dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole, uint64_t *off)
1675 {
1676         dnode_t *dn;
1677         int i, err;
1678 
1679         err = dnode_hold(os, object, FTAG, &dn);
1680         if (err)
1681                 return (err);
1682         /*
1683          * Sync any current changes before
1684          * we go trundling through the block pointers.
1685          */
1686         for (i = 0; i < TXG_SIZE; i++) {
1687                 if (list_link_active(&dn->dn_dirty_link[i]))
1688                         break;
1689         }
1690         if (i != TXG_SIZE) {
1691                 dnode_rele(dn, FTAG);
1692                 txg_wait_synced(dmu_objset_pool(os), 0);
1693                 err = dnode_hold(os, object, FTAG, &dn);
1694                 if (err)
1695                         return (err);
1696         }
1697 
1698         err = dnode_next_offset(dn, (hole ? DNODE_FIND_HOLE : 0), off, 1, 1, 0);
1699         dnode_rele(dn, FTAG);
1700 
1701         return (err);
1702 }
1703 
1704 void
1705 dmu_object_info_from_dnode(dnode_t *dn, dmu_object_info_t *doi)
1706 {
1707         dnode_phys_t *dnp;
1708 
1709         rw_enter(&dn->dn_struct_rwlock, RW_READER);
1710         mutex_enter(&dn->dn_mtx);
1711 
1712         dnp = dn->dn_phys;
1713 
1714         doi->doi_data_block_size = dn->dn_datablksz;
1715         doi->doi_metadata_block_size = dn->dn_indblkshift ?
1716             1ULL << dn->dn_indblkshift : 0;
1717         doi->doi_type = dn->dn_type;
1718         doi->doi_bonus_type = dn->dn_bonustype;
1719         doi->doi_bonus_size = dn->dn_bonuslen;
1720         doi->doi_indirection = dn->dn_nlevels;
1721         doi->doi_checksum = dn->dn_checksum;
1722         doi->doi_compress = dn->dn_compress;
1723         doi->doi_physical_blocks_512 = (DN_USED_BYTES(dnp) + 256) >> 9;
1724         doi->doi_max_offset = (dn->dn_maxblkid + 1) * dn->dn_datablksz;
1725         doi->doi_fill_count = 0;
1726         for (int i = 0; i < dnp->dn_nblkptr; i++)
1727                 doi->doi_fill_count += dnp->dn_blkptr[i].blk_fill;
1728 
1729         mutex_exit(&dn->dn_mtx);
1730         rw_exit(&dn->dn_struct_rwlock);
1731 }
1732 
1733 /*
1734  * Get information on a DMU object.
1735  * If doi is NULL, just indicates whether the object exists.
1736  */
1737 int
1738 dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi)
1739 {
1740         dnode_t *dn;
1741         int err = dnode_hold(os, object, FTAG, &dn);
1742 
1743         if (err)
1744                 return (err);
1745 
1746         if (doi != NULL)
1747                 dmu_object_info_from_dnode(dn, doi);
1748 
1749         dnode_rele(dn, FTAG);
1750         return (0);
1751 }
1752 
1753 /*
1754  * As above, but faster; can be used when you have a held dbuf in hand.
1755  */
1756 void
1757 dmu_object_info_from_db(dmu_buf_t *db_fake, dmu_object_info_t *doi)
1758 {
1759         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1760 
1761         DB_DNODE_ENTER(db);
1762         dmu_object_info_from_dnode(DB_DNODE(db), doi);
1763         DB_DNODE_EXIT(db);
1764 }
1765 
1766 /*
1767  * Faster still when you only care about the size.
1768  * This is specifically optimized for zfs_getattr().
1769  */
1770 void
1771 dmu_object_size_from_db(dmu_buf_t *db_fake, uint32_t *blksize,
1772     u_longlong_t *nblk512)
1773 {
1774         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1775         dnode_t *dn;
1776 
1777         DB_DNODE_ENTER(db);
1778         dn = DB_DNODE(db);
1779 
1780         *blksize = dn->dn_datablksz;
1781         /* add 1 for dnode space */
1782         *nblk512 = ((DN_USED_BYTES(dn->dn_phys) + SPA_MINBLOCKSIZE/2) >>
1783             SPA_MINBLOCKSHIFT) + 1;
1784         DB_DNODE_EXIT(db);
1785 }
1786 
1787 void
1788 byteswap_uint64_array(void *vbuf, size_t size)
1789 {
1790         uint64_t *buf = vbuf;
1791         size_t count = size >> 3;
1792         int i;
1793 
1794         ASSERT((size & 7) == 0);
1795 
1796         for (i = 0; i < count; i++)
1797                 buf[i] = BSWAP_64(buf[i]);
1798 }
1799 
1800 void
1801 byteswap_uint32_array(void *vbuf, size_t size)
1802 {
1803         uint32_t *buf = vbuf;
1804         size_t count = size >> 2;
1805         int i;
1806 
1807         ASSERT((size & 3) == 0);
1808 
1809         for (i = 0; i < count; i++)
1810                 buf[i] = BSWAP_32(buf[i]);
1811 }
1812 
1813 void
1814 byteswap_uint16_array(void *vbuf, size_t size)
1815 {
1816         uint16_t *buf = vbuf;
1817         size_t count = size >> 1;
1818         int i;
1819 
1820         ASSERT((size & 1) == 0);
1821 
1822         for (i = 0; i < count; i++)
1823                 buf[i] = BSWAP_16(buf[i]);
1824 }
1825 
1826 /* ARGSUSED */
1827 void
1828 byteswap_uint8_array(void *vbuf, size_t size)
1829 {
1830 }
1831 
1832 void
1833 dmu_init(void)
1834 {
1835         zfs_dbgmsg_init();
1836         sa_cache_init();
1837         xuio_stat_init();
1838         dmu_objset_init();
1839         dnode_init();
1840         dbuf_init();
1841         zfetch_init();
1842         l2arc_init();
1843         arc_init();
1844 }
1845 
1846 void
1847 dmu_fini(void)
1848 {
1849         arc_fini();
1850         l2arc_fini();
1851         zfetch_fini();
1852         dbuf_fini();
1853         dnode_fini();
1854         dmu_objset_fini();
1855         xuio_stat_fini();
1856         sa_cache_fini();
1857         zfs_dbgmsg_fini();
1858 }