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  */
  25 
  26 /* Copyright (c) 2013 by Saso Kiselkov. 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         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  * On input, *start should be the first offset that does not need to be
 574  * freed (e.g. "offset + length").  On return, *start will be the first
 575  * offset that should be freed.
 576  */
 577 static int
 578 get_next_chunk(dnode_t *dn, uint64_t *start, uint64_t minimum)
 579 {
 580         uint64_t maxblks = DMU_MAX_ACCESS >> (dn->dn_indblkshift + 1);
 581         /* bytes of data covered by a level-1 indirect block */
 582         uint64_t iblkrange =
 583             dn->dn_datablksz * EPB(dn->dn_indblkshift, SPA_BLKPTRSHIFT);
 584 
 585         ASSERT3U(minimum, <=, *start);
 586 
 587         if (*start - minimum <= iblkrange * maxblks) {
 588                 *start = minimum;
 589                 return (0);
 590         }
 591         ASSERT(ISP2(iblkrange));
 592 
 593         for (uint64_t blks = 0; *start > minimum && blks < maxblks; blks++) {
 594                 int err;
 595 
 596                 /*
 597                  * dnode_next_offset(BACKWARDS) will find an allocated L1
 598                  * indirect block at or before the input offset.  We must
 599                  * decrement *start so that it is at the end of the region
 600                  * to search.
 601                  */
 602                 (*start)--;
 603                 err = dnode_next_offset(dn,
 604                     DNODE_FIND_BACKWARDS, start, 2, 1, 0);
 605 
 606                 /* if there are no indirect blocks before start, we are done */
 607                 if (err == ESRCH) {
 608                         *start = minimum;
 609                         break;
 610                 } else if (err != 0) {
 611                         return (err);
 612                 }
 613 
 614                 /* set start to the beginning of this L1 indirect */
 615                 *start = P2ALIGN(*start, iblkrange);
 616         }
 617         if (*start < minimum)
 618                 *start = minimum;
 619         return (0);
 620 }
 621 
 622 static int
 623 dmu_free_long_range_impl(objset_t *os, dnode_t *dn, uint64_t offset,
 624     uint64_t length)
 625 {
 626         uint64_t object_size = (dn->dn_maxblkid + 1) * dn->dn_datablksz;
 627         int err;
 628 
 629         if (offset >= object_size)
 630                 return (0);
 631 
 632         if (length == DMU_OBJECT_END || offset + length > object_size)
 633                 length = object_size - offset;
 634 
 635         while (length != 0) {
 636                 uint64_t chunk_end, chunk_begin;
 637 
 638                 chunk_end = chunk_begin = offset + length;
 639 
 640                 /* move chunk_begin backwards to the beginning of this chunk */
 641                 err = get_next_chunk(dn, &chunk_begin, offset);
 642                 if (err)
 643                         return (err);
 644                 ASSERT3U(chunk_begin, >=, offset);
 645                 ASSERT3U(chunk_begin, <=, chunk_end);
 646 
 647                 dmu_tx_t *tx = dmu_tx_create(os);
 648                 dmu_tx_hold_free(tx, dn->dn_object,
 649                     chunk_begin, chunk_end - chunk_begin);
 650                 err = dmu_tx_assign(tx, TXG_WAIT);
 651                 if (err) {
 652                         dmu_tx_abort(tx);
 653                         return (err);
 654                 }
 655                 dnode_free_range(dn, chunk_begin, chunk_end - chunk_begin, tx);
 656                 dmu_tx_commit(tx);
 657 
 658                 length -= chunk_end - chunk_begin;
 659         }
 660         return (0);
 661 }
 662 
 663 int
 664 dmu_free_long_range(objset_t *os, uint64_t object,
 665     uint64_t offset, uint64_t length)
 666 {
 667         dnode_t *dn;
 668         int err;
 669 
 670         err = dnode_hold(os, object, FTAG, &dn);
 671         if (err != 0)
 672                 return (err);
 673         err = dmu_free_long_range_impl(os, dn, offset, length);
 674         dnode_rele(dn, FTAG);
 675         return (err);
 676 }
 677 
 678 int
 679 dmu_free_long_object(objset_t *os, uint64_t object)
 680 {
 681         dmu_tx_t *tx;
 682         int err;
 683 
 684         err = dmu_free_long_range(os, object, 0, DMU_OBJECT_END);
 685         if (err != 0)
 686                 return (err);
 687 
 688         tx = dmu_tx_create(os);
 689         dmu_tx_hold_bonus(tx, object);
 690         dmu_tx_hold_free(tx, object, 0, DMU_OBJECT_END);
 691         err = dmu_tx_assign(tx, TXG_WAIT);
 692         if (err == 0) {
 693                 err = dmu_object_free(os, object, tx);
 694                 dmu_tx_commit(tx);
 695         } else {
 696                 dmu_tx_abort(tx);
 697         }
 698 
 699         return (err);
 700 }
 701 
 702 int
 703 dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
 704     uint64_t size, dmu_tx_t *tx)
 705 {
 706         dnode_t *dn;
 707         int err = dnode_hold(os, object, FTAG, &dn);
 708         if (err)
 709                 return (err);
 710         ASSERT(offset < UINT64_MAX);
 711         ASSERT(size == -1ULL || size <= UINT64_MAX - offset);
 712         dnode_free_range(dn, offset, size, tx);
 713         dnode_rele(dn, FTAG);
 714         return (0);
 715 }
 716 
 717 int
 718 dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 719     void *buf, uint32_t flags)
 720 {
 721         dnode_t *dn;
 722         dmu_buf_t **dbp;
 723         int numbufs, err;
 724 
 725         err = dnode_hold(os, object, FTAG, &dn);
 726         if (err)
 727                 return (err);
 728 
 729         /*
 730          * Deal with odd block sizes, where there can't be data past the first
 731          * block.  If we ever do the tail block optimization, we will need to
 732          * handle that here as well.
 733          */
 734         if (dn->dn_maxblkid == 0) {
 735                 int newsz = offset > dn->dn_datablksz ? 0 :
 736                     MIN(size, dn->dn_datablksz - offset);
 737                 bzero((char *)buf + newsz, size - newsz);
 738                 size = newsz;
 739         }
 740 
 741         while (size > 0) {
 742                 uint64_t mylen = MIN(size, DMU_MAX_ACCESS / 2);
 743                 int i;
 744 
 745                 /*
 746                  * NB: we could do this block-at-a-time, but it's nice
 747                  * to be reading in parallel.
 748                  */
 749                 err = dmu_buf_hold_array_by_dnode(dn, offset, mylen,
 750                     TRUE, FTAG, &numbufs, &dbp, flags);
 751                 if (err)
 752                         break;
 753 
 754                 for (i = 0; i < numbufs; i++) {
 755                         int tocpy;
 756                         int bufoff;
 757                         dmu_buf_t *db = dbp[i];
 758 
 759                         ASSERT(size > 0);
 760 
 761                         bufoff = offset - db->db_offset;
 762                         tocpy = (int)MIN(db->db_size - bufoff, size);
 763 
 764                         bcopy((char *)db->db_data + bufoff, buf, tocpy);
 765 
 766                         offset += tocpy;
 767                         size -= tocpy;
 768                         buf = (char *)buf + tocpy;
 769                 }
 770                 dmu_buf_rele_array(dbp, numbufs, FTAG);
 771         }
 772         dnode_rele(dn, FTAG);
 773         return (err);
 774 }
 775 
 776 void
 777 dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 778     const void *buf, dmu_tx_t *tx)
 779 {
 780         dmu_buf_t **dbp;
 781         int numbufs, i;
 782 
 783         if (size == 0)
 784                 return;
 785 
 786         VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
 787             FALSE, FTAG, &numbufs, &dbp));
 788 
 789         for (i = 0; i < numbufs; i++) {
 790                 int tocpy;
 791                 int bufoff;
 792                 dmu_buf_t *db = dbp[i];
 793 
 794                 ASSERT(size > 0);
 795 
 796                 bufoff = offset - db->db_offset;
 797                 tocpy = (int)MIN(db->db_size - bufoff, size);
 798 
 799                 ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
 800 
 801                 if (tocpy == db->db_size)
 802                         dmu_buf_will_fill(db, tx);
 803                 else
 804                         dmu_buf_will_dirty(db, tx);
 805 
 806                 bcopy(buf, (char *)db->db_data + bufoff, tocpy);
 807 
 808                 if (tocpy == db->db_size)
 809                         dmu_buf_fill_done(db, tx);
 810 
 811                 offset += tocpy;
 812                 size -= tocpy;
 813                 buf = (char *)buf + tocpy;
 814         }
 815         dmu_buf_rele_array(dbp, numbufs, FTAG);
 816 }
 817 
 818 void
 819 dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 820     dmu_tx_t *tx)
 821 {
 822         dmu_buf_t **dbp;
 823         int numbufs, i;
 824 
 825         if (size == 0)
 826                 return;
 827 
 828         VERIFY(0 == dmu_buf_hold_array(os, object, offset, size,
 829             FALSE, FTAG, &numbufs, &dbp));
 830 
 831         for (i = 0; i < numbufs; i++) {
 832                 dmu_buf_t *db = dbp[i];
 833 
 834                 dmu_buf_will_not_fill(db, tx);
 835         }
 836         dmu_buf_rele_array(dbp, numbufs, FTAG);
 837 }
 838 
 839 /*
 840  * DMU support for xuio
 841  */
 842 kstat_t *xuio_ksp = NULL;
 843 
 844 int
 845 dmu_xuio_init(xuio_t *xuio, int nblk)
 846 {
 847         dmu_xuio_t *priv;
 848         uio_t *uio = &xuio->xu_uio;
 849 
 850         uio->uio_iovcnt = nblk;
 851         uio->uio_iov = kmem_zalloc(nblk * sizeof (iovec_t), KM_SLEEP);
 852 
 853         priv = kmem_zalloc(sizeof (dmu_xuio_t), KM_SLEEP);
 854         priv->cnt = nblk;
 855         priv->bufs = kmem_zalloc(nblk * sizeof (arc_buf_t *), KM_SLEEP);
 856         priv->iovp = uio->uio_iov;
 857         XUIO_XUZC_PRIV(xuio) = priv;
 858 
 859         if (XUIO_XUZC_RW(xuio) == UIO_READ)
 860                 XUIOSTAT_INCR(xuiostat_onloan_rbuf, nblk);
 861         else
 862                 XUIOSTAT_INCR(xuiostat_onloan_wbuf, nblk);
 863 
 864         return (0);
 865 }
 866 
 867 void
 868 dmu_xuio_fini(xuio_t *xuio)
 869 {
 870         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 871         int nblk = priv->cnt;
 872 
 873         kmem_free(priv->iovp, nblk * sizeof (iovec_t));
 874         kmem_free(priv->bufs, nblk * sizeof (arc_buf_t *));
 875         kmem_free(priv, sizeof (dmu_xuio_t));
 876 
 877         if (XUIO_XUZC_RW(xuio) == UIO_READ)
 878                 XUIOSTAT_INCR(xuiostat_onloan_rbuf, -nblk);
 879         else
 880                 XUIOSTAT_INCR(xuiostat_onloan_wbuf, -nblk);
 881 }
 882 
 883 /*
 884  * Initialize iov[priv->next] and priv->bufs[priv->next] with { off, n, abuf }
 885  * and increase priv->next by 1.
 886  */
 887 int
 888 dmu_xuio_add(xuio_t *xuio, arc_buf_t *abuf, offset_t off, size_t n)
 889 {
 890         struct iovec *iov;
 891         uio_t *uio = &xuio->xu_uio;
 892         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 893         int i = priv->next++;
 894 
 895         ASSERT(i < priv->cnt);
 896         ASSERT(off + n <= arc_buf_size(abuf));
 897         iov = uio->uio_iov + i;
 898         iov->iov_base = (char *)abuf->b_data + off;
 899         iov->iov_len = n;
 900         priv->bufs[i] = abuf;
 901         return (0);
 902 }
 903 
 904 int
 905 dmu_xuio_cnt(xuio_t *xuio)
 906 {
 907         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 908         return (priv->cnt);
 909 }
 910 
 911 arc_buf_t *
 912 dmu_xuio_arcbuf(xuio_t *xuio, int i)
 913 {
 914         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 915 
 916         ASSERT(i < priv->cnt);
 917         return (priv->bufs[i]);
 918 }
 919 
 920 void
 921 dmu_xuio_clear(xuio_t *xuio, int i)
 922 {
 923         dmu_xuio_t *priv = XUIO_XUZC_PRIV(xuio);
 924 
 925         ASSERT(i < priv->cnt);
 926         priv->bufs[i] = NULL;
 927 }
 928 
 929 static void
 930 xuio_stat_init(void)
 931 {
 932         xuio_ksp = kstat_create("zfs", 0, "xuio_stats", "misc",
 933             KSTAT_TYPE_NAMED, sizeof (xuio_stats) / sizeof (kstat_named_t),
 934             KSTAT_FLAG_VIRTUAL);
 935         if (xuio_ksp != NULL) {
 936                 xuio_ksp->ks_data = &xuio_stats;
 937                 kstat_install(xuio_ksp);
 938         }
 939 }
 940 
 941 static void
 942 xuio_stat_fini(void)
 943 {
 944         if (xuio_ksp != NULL) {
 945                 kstat_delete(xuio_ksp);
 946                 xuio_ksp = NULL;
 947         }
 948 }
 949 
 950 void
 951 xuio_stat_wbuf_copied()
 952 {
 953         XUIOSTAT_BUMP(xuiostat_wbuf_copied);
 954 }
 955 
 956 void
 957 xuio_stat_wbuf_nocopy()
 958 {
 959         XUIOSTAT_BUMP(xuiostat_wbuf_nocopy);
 960 }
 961 
 962 #ifdef _KERNEL
 963 int
 964 dmu_read_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size)
 965 {
 966         dmu_buf_t **dbp;
 967         int numbufs, i, err;
 968         xuio_t *xuio = NULL;
 969 
 970         /*
 971          * NB: we could do this block-at-a-time, but it's nice
 972          * to be reading in parallel.
 973          */
 974         err = dmu_buf_hold_array(os, object, uio->uio_loffset, size, TRUE, FTAG,
 975             &numbufs, &dbp);
 976         if (err)
 977                 return (err);
 978 
 979         if (uio->uio_extflg == UIO_XUIO)
 980                 xuio = (xuio_t *)uio;
 981 
 982         for (i = 0; i < numbufs; i++) {
 983                 int tocpy;
 984                 int bufoff;
 985                 dmu_buf_t *db = dbp[i];
 986 
 987                 ASSERT(size > 0);
 988 
 989                 bufoff = uio->uio_loffset - db->db_offset;
 990                 tocpy = (int)MIN(db->db_size - bufoff, size);
 991 
 992                 if (xuio) {
 993                         dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
 994                         arc_buf_t *dbuf_abuf = dbi->db_buf;
 995                         arc_buf_t *abuf = dbuf_loan_arcbuf(dbi);
 996                         err = dmu_xuio_add(xuio, abuf, bufoff, tocpy);
 997                         if (!err) {
 998                                 uio->uio_resid -= tocpy;
 999                                 uio->uio_loffset += tocpy;
1000                         }
1001 
1002                         if (abuf == dbuf_abuf)
1003                                 XUIOSTAT_BUMP(xuiostat_rbuf_nocopy);
1004                         else
1005                                 XUIOSTAT_BUMP(xuiostat_rbuf_copied);
1006                 } else {
1007                         err = uiomove((char *)db->db_data + bufoff, tocpy,
1008                             UIO_READ, uio);
1009                 }
1010                 if (err)
1011                         break;
1012 
1013                 size -= tocpy;
1014         }
1015         dmu_buf_rele_array(dbp, numbufs, FTAG);
1016 
1017         return (err);
1018 }
1019 
1020 static int
1021 dmu_write_uio_dnode(dnode_t *dn, uio_t *uio, uint64_t size, dmu_tx_t *tx)
1022 {
1023         dmu_buf_t **dbp;
1024         int numbufs;
1025         int err = 0;
1026         int i;
1027 
1028         err = dmu_buf_hold_array_by_dnode(dn, uio->uio_loffset, size,
1029             FALSE, FTAG, &numbufs, &dbp, DMU_READ_PREFETCH);
1030         if (err)
1031                 return (err);
1032 
1033         for (i = 0; i < numbufs; i++) {
1034                 int tocpy;
1035                 int bufoff;
1036                 dmu_buf_t *db = dbp[i];
1037 
1038                 ASSERT(size > 0);
1039 
1040                 bufoff = uio->uio_loffset - db->db_offset;
1041                 tocpy = (int)MIN(db->db_size - bufoff, size);
1042 
1043                 ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
1044 
1045                 if (tocpy == db->db_size)
1046                         dmu_buf_will_fill(db, tx);
1047                 else
1048                         dmu_buf_will_dirty(db, tx);
1049 
1050                 /*
1051                  * XXX uiomove could block forever (eg. nfs-backed
1052                  * pages).  There needs to be a uiolockdown() function
1053                  * to lock the pages in memory, so that uiomove won't
1054                  * block.
1055                  */
1056                 err = uiomove((char *)db->db_data + bufoff, tocpy,
1057                     UIO_WRITE, uio);
1058 
1059                 if (tocpy == db->db_size)
1060                         dmu_buf_fill_done(db, tx);
1061 
1062                 if (err)
1063                         break;
1064 
1065                 size -= tocpy;
1066         }
1067 
1068         dmu_buf_rele_array(dbp, numbufs, FTAG);
1069         return (err);
1070 }
1071 
1072 int
1073 dmu_write_uio_dbuf(dmu_buf_t *zdb, uio_t *uio, uint64_t size,
1074     dmu_tx_t *tx)
1075 {
1076         dmu_buf_impl_t *db = (dmu_buf_impl_t *)zdb;
1077         dnode_t *dn;
1078         int err;
1079 
1080         if (size == 0)
1081                 return (0);
1082 
1083         DB_DNODE_ENTER(db);
1084         dn = DB_DNODE(db);
1085         err = dmu_write_uio_dnode(dn, uio, size, tx);
1086         DB_DNODE_EXIT(db);
1087 
1088         return (err);
1089 }
1090 
1091 int
1092 dmu_write_uio(objset_t *os, uint64_t object, uio_t *uio, uint64_t size,
1093     dmu_tx_t *tx)
1094 {
1095         dnode_t *dn;
1096         int err;
1097 
1098         if (size == 0)
1099                 return (0);
1100 
1101         err = dnode_hold(os, object, FTAG, &dn);
1102         if (err)
1103                 return (err);
1104 
1105         err = dmu_write_uio_dnode(dn, uio, size, tx);
1106 
1107         dnode_rele(dn, FTAG);
1108 
1109         return (err);
1110 }
1111 
1112 int
1113 dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
1114     page_t *pp, dmu_tx_t *tx)
1115 {
1116         dmu_buf_t **dbp;
1117         int numbufs, i;
1118         int err;
1119 
1120         if (size == 0)
1121                 return (0);
1122 
1123         err = dmu_buf_hold_array(os, object, offset, size,
1124             FALSE, FTAG, &numbufs, &dbp);
1125         if (err)
1126                 return (err);
1127 
1128         for (i = 0; i < numbufs; i++) {
1129                 int tocpy, copied, thiscpy;
1130                 int bufoff;
1131                 dmu_buf_t *db = dbp[i];
1132                 caddr_t va;
1133 
1134                 ASSERT(size > 0);
1135                 ASSERT3U(db->db_size, >=, PAGESIZE);
1136 
1137                 bufoff = offset - db->db_offset;
1138                 tocpy = (int)MIN(db->db_size - bufoff, size);
1139 
1140                 ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);
1141 
1142                 if (tocpy == db->db_size)
1143                         dmu_buf_will_fill(db, tx);
1144                 else
1145                         dmu_buf_will_dirty(db, tx);
1146 
1147                 for (copied = 0; copied < tocpy; copied += PAGESIZE) {
1148                         ASSERT3U(pp->p_offset, ==, db->db_offset + bufoff);
1149                         thiscpy = MIN(PAGESIZE, tocpy - copied);
1150                         va = zfs_map_page(pp, S_READ);
1151                         bcopy(va, (char *)db->db_data + bufoff, thiscpy);
1152                         zfs_unmap_page(pp, va);
1153                         pp = pp->p_next;
1154                         bufoff += PAGESIZE;
1155                 }
1156 
1157                 if (tocpy == db->db_size)
1158                         dmu_buf_fill_done(db, tx);
1159 
1160                 offset += tocpy;
1161                 size -= tocpy;
1162         }
1163         dmu_buf_rele_array(dbp, numbufs, FTAG);
1164         return (err);
1165 }
1166 #endif
1167 
1168 /*
1169  * Allocate a loaned anonymous arc buffer.
1170  */
1171 arc_buf_t *
1172 dmu_request_arcbuf(dmu_buf_t *handle, int size)
1173 {
1174         dmu_buf_impl_t *db = (dmu_buf_impl_t *)handle;
1175         spa_t *spa;
1176 
1177         DB_GET_SPA(&spa, db);
1178         return (arc_loan_buf(spa, size));
1179 }
1180 
1181 /*
1182  * Free a loaned arc buffer.
1183  */
1184 void
1185 dmu_return_arcbuf(arc_buf_t *buf)
1186 {
1187         arc_return_buf(buf, FTAG);
1188         VERIFY(arc_buf_remove_ref(buf, FTAG));
1189 }
1190 
1191 /*
1192  * When possible directly assign passed loaned arc buffer to a dbuf.
1193  * If this is not possible copy the contents of passed arc buf via
1194  * dmu_write().
1195  */
1196 void
1197 dmu_assign_arcbuf(dmu_buf_t *handle, uint64_t offset, arc_buf_t *buf,
1198     dmu_tx_t *tx)
1199 {
1200         dmu_buf_impl_t *dbuf = (dmu_buf_impl_t *)handle;
1201         dnode_t *dn;
1202         dmu_buf_impl_t *db;
1203         uint32_t blksz = (uint32_t)arc_buf_size(buf);
1204         uint64_t blkid;
1205 
1206         DB_DNODE_ENTER(dbuf);
1207         dn = DB_DNODE(dbuf);
1208         rw_enter(&dn->dn_struct_rwlock, RW_READER);
1209         blkid = dbuf_whichblock(dn, offset);
1210         VERIFY((db = dbuf_hold(dn, blkid, FTAG)) != NULL);
1211         rw_exit(&dn->dn_struct_rwlock);
1212         DB_DNODE_EXIT(dbuf);
1213 
1214         if (offset == db->db.db_offset && blksz == db->db.db_size) {
1215                 dbuf_assign_arcbuf(db, buf, tx);
1216                 dbuf_rele(db, FTAG);
1217         } else {
1218                 objset_t *os;
1219                 uint64_t object;
1220 
1221                 DB_DNODE_ENTER(dbuf);
1222                 dn = DB_DNODE(dbuf);
1223                 os = dn->dn_objset;
1224                 object = dn->dn_object;
1225                 DB_DNODE_EXIT(dbuf);
1226 
1227                 dbuf_rele(db, FTAG);
1228                 dmu_write(os, object, offset, blksz, buf->b_data, tx);
1229                 dmu_return_arcbuf(buf);
1230                 XUIOSTAT_BUMP(xuiostat_wbuf_copied);
1231         }
1232 }
1233 
1234 typedef struct {
1235         dbuf_dirty_record_t     *dsa_dr;
1236         dmu_sync_cb_t           *dsa_done;
1237         zgd_t                   *dsa_zgd;
1238         dmu_tx_t                *dsa_tx;
1239 } dmu_sync_arg_t;
1240 
1241 /* ARGSUSED */
1242 static void
1243 dmu_sync_ready(zio_t *zio, arc_buf_t *buf, void *varg)
1244 {
1245         dmu_sync_arg_t *dsa = varg;
1246         dmu_buf_t *db = dsa->dsa_zgd->zgd_db;
1247         blkptr_t *bp = zio->io_bp;
1248 
1249         if (zio->io_error == 0) {
1250                 if (BP_IS_HOLE(bp)) {
1251                         /*
1252                          * A block of zeros may compress to a hole, but the
1253                          * block size still needs to be known for replay.
1254                          */
1255                         BP_SET_LSIZE(bp, db->db_size);
1256                 } else {
1257                         ASSERT(BP_GET_LEVEL(bp) == 0);
1258                         bp->blk_fill = 1;
1259                 }
1260         }
1261 }
1262 
1263 static void
1264 dmu_sync_late_arrival_ready(zio_t *zio)
1265 {
1266         dmu_sync_ready(zio, NULL, zio->io_private);
1267 }
1268 
1269 /* ARGSUSED */
1270 static void
1271 dmu_sync_done(zio_t *zio, arc_buf_t *buf, void *varg)
1272 {
1273         dmu_sync_arg_t *dsa = varg;
1274         dbuf_dirty_record_t *dr = dsa->dsa_dr;
1275         dmu_buf_impl_t *db = dr->dr_dbuf;
1276 
1277         mutex_enter(&db->db_mtx);
1278         ASSERT(dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC);
1279         if (zio->io_error == 0) {
1280                 dr->dt.dl.dr_nopwrite = !!(zio->io_flags & ZIO_FLAG_NOPWRITE);
1281                 if (dr->dt.dl.dr_nopwrite) {
1282                         blkptr_t *bp = zio->io_bp;
1283                         blkptr_t *bp_orig = &zio->io_bp_orig;
1284                         uint8_t chksum = BP_GET_CHECKSUM(bp_orig);
1285 
1286                         ASSERT(BP_EQUAL(bp, bp_orig));
1287                         ASSERT(zio->io_prop.zp_compress != ZIO_COMPRESS_OFF);
1288                         ASSERT(zio_checksum_table[chksum].ci_dedup);
1289                 }
1290                 dr->dt.dl.dr_overridden_by = *zio->io_bp;
1291                 dr->dt.dl.dr_override_state = DR_OVERRIDDEN;
1292                 dr->dt.dl.dr_copies = zio->io_prop.zp_copies;
1293                 if (BP_IS_HOLE(&dr->dt.dl.dr_overridden_by))
1294                         BP_ZERO(&dr->dt.dl.dr_overridden_by);
1295         } else {
1296                 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
1297         }
1298         cv_broadcast(&db->db_changed);
1299         mutex_exit(&db->db_mtx);
1300 
1301         dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
1302 
1303         kmem_free(dsa, sizeof (*dsa));
1304 }
1305 
1306 static void
1307 dmu_sync_late_arrival_done(zio_t *zio)
1308 {
1309         blkptr_t *bp = zio->io_bp;
1310         dmu_sync_arg_t *dsa = zio->io_private;
1311         blkptr_t *bp_orig = &zio->io_bp_orig;
1312 
1313         if (zio->io_error == 0 && !BP_IS_HOLE(bp)) {
1314                 /*
1315                  * If we didn't allocate a new block (i.e. ZIO_FLAG_NOPWRITE)
1316                  * then there is nothing to do here. Otherwise, free the
1317                  * newly allocated block in this txg.
1318                  */
1319                 if (zio->io_flags & ZIO_FLAG_NOPWRITE) {
1320                         ASSERT(BP_EQUAL(bp, bp_orig));
1321                 } else {
1322                         ASSERT(BP_IS_HOLE(bp_orig) || !BP_EQUAL(bp, bp_orig));
1323                         ASSERT(zio->io_bp->blk_birth == zio->io_txg);
1324                         ASSERT(zio->io_txg > spa_syncing_txg(zio->io_spa));
1325                         zio_free(zio->io_spa, zio->io_txg, zio->io_bp);
1326                 }
1327         }
1328 
1329         dmu_tx_commit(dsa->dsa_tx);
1330 
1331         dsa->dsa_done(dsa->dsa_zgd, zio->io_error);
1332 
1333         kmem_free(dsa, sizeof (*dsa));
1334 }
1335 
1336 static int
1337 dmu_sync_late_arrival(zio_t *pio, objset_t *os, dmu_sync_cb_t *done, zgd_t *zgd,
1338     zio_prop_t *zp, zbookmark_t *zb)
1339 {
1340         dmu_sync_arg_t *dsa;
1341         dmu_tx_t *tx;
1342 
1343         tx = dmu_tx_create(os);
1344         dmu_tx_hold_space(tx, zgd->zgd_db->db_size);
1345         if (dmu_tx_assign(tx, TXG_WAIT) != 0) {
1346                 dmu_tx_abort(tx);
1347                 /* Make zl_get_data do txg_waited_synced() */
1348                 return (SET_ERROR(EIO));
1349         }
1350 
1351         dsa = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
1352         dsa->dsa_dr = NULL;
1353         dsa->dsa_done = done;
1354         dsa->dsa_zgd = zgd;
1355         dsa->dsa_tx = tx;
1356 
1357         zio_nowait(zio_write(pio, os->os_spa, dmu_tx_get_txg(tx), zgd->zgd_bp,
1358             zgd->zgd_db->db_data, zgd->zgd_db->db_size, zp,
1359             dmu_sync_late_arrival_ready, dmu_sync_late_arrival_done, dsa,
1360             ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_CANFAIL, zb));
1361 
1362         return (0);
1363 }
1364 
1365 /*
1366  * Intent log support: sync the block associated with db to disk.
1367  * N.B. and XXX: the caller is responsible for making sure that the
1368  * data isn't changing while dmu_sync() is writing it.
1369  *
1370  * Return values:
1371  *
1372  *      EEXIST: this txg has already been synced, so there's nothing to do.
1373  *              The caller should not log the write.
1374  *
1375  *      ENOENT: the block was dbuf_free_range()'d, so there's nothing to do.
1376  *              The caller should not log the write.
1377  *
1378  *      EALREADY: this block is already in the process of being synced.
1379  *              The caller should track its progress (somehow).
1380  *
1381  *      EIO: could not do the I/O.
1382  *              The caller should do a txg_wait_synced().
1383  *
1384  *      0: the I/O has been initiated.
1385  *              The caller should log this blkptr in the done callback.
1386  *              It is possible that the I/O will fail, in which case
1387  *              the error will be reported to the done callback and
1388  *              propagated to pio from zio_done().
1389  */
1390 int
1391 dmu_sync(zio_t *pio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd)
1392 {
1393         blkptr_t *bp = zgd->zgd_bp;
1394         dmu_buf_impl_t *db = (dmu_buf_impl_t *)zgd->zgd_db;
1395         objset_t *os = db->db_objset;
1396         dsl_dataset_t *ds = os->os_dsl_dataset;
1397         dbuf_dirty_record_t *dr;
1398         dmu_sync_arg_t *dsa;
1399         zbookmark_t zb;
1400         zio_prop_t zp;
1401         dnode_t *dn;
1402 
1403         ASSERT(pio != NULL);
1404         ASSERT(txg != 0);
1405 
1406         SET_BOOKMARK(&zb, ds->ds_object,
1407             db->db.db_object, db->db_level, db->db_blkid);
1408 
1409         DB_DNODE_ENTER(db);
1410         dn = DB_DNODE(db);
1411         dmu_write_policy(os, dn, db->db_level, WP_DMU_SYNC, &zp);
1412         DB_DNODE_EXIT(db);
1413 
1414         /*
1415          * If we're frozen (running ziltest), we always need to generate a bp.
1416          */
1417         if (txg > spa_freeze_txg(os->os_spa))
1418                 return (dmu_sync_late_arrival(pio, os, done, zgd, &zp, &zb));
1419 
1420         /*
1421          * Grabbing db_mtx now provides a barrier between dbuf_sync_leaf()
1422          * and us.  If we determine that this txg is not yet syncing,
1423          * but it begins to sync a moment later, that's OK because the
1424          * sync thread will block in dbuf_sync_leaf() until we drop db_mtx.
1425          */
1426         mutex_enter(&db->db_mtx);
1427 
1428         if (txg <= spa_last_synced_txg(os->os_spa)) {
1429                 /*
1430                  * This txg has already synced.  There's nothing to do.
1431                  */
1432                 mutex_exit(&db->db_mtx);
1433                 return (SET_ERROR(EEXIST));
1434         }
1435 
1436         if (txg <= spa_syncing_txg(os->os_spa)) {
1437                 /*
1438                  * This txg is currently syncing, so we can't mess with
1439                  * the dirty record anymore; just write a new log block.
1440                  */
1441                 mutex_exit(&db->db_mtx);
1442                 return (dmu_sync_late_arrival(pio, os, done, zgd, &zp, &zb));
1443         }
1444 
1445         dr = db->db_last_dirty;
1446         while (dr && dr->dr_txg != txg)
1447                 dr = dr->dr_next;
1448 
1449         if (dr == NULL) {
1450                 /*
1451                  * There's no dr for this dbuf, so it must have been freed.
1452                  * There's no need to log writes to freed blocks, so we're done.
1453                  */
1454                 mutex_exit(&db->db_mtx);
1455                 return (SET_ERROR(ENOENT));
1456         }
1457 
1458         ASSERT(dr->dr_next == NULL || dr->dr_next->dr_txg < txg);
1459 
1460         /*
1461          * Assume the on-disk data is X, the current syncing data is Y,
1462          * and the current in-memory data is Z (currently in dmu_sync).
1463          * X and Z are identical but Y is has been modified. Normally,
1464          * when X and Z are the same we will perform a nopwrite but if Y
1465          * is different we must disable nopwrite since the resulting write
1466          * of Y to disk can free the block containing X. If we allowed a
1467          * nopwrite to occur the block pointing to Z would reference a freed
1468          * block. Since this is a rare case we simplify this by disabling
1469          * nopwrite if the current dmu_sync-ing dbuf has been modified in
1470          * a previous transaction.
1471          */
1472         if (dr->dr_next)
1473                 zp.zp_nopwrite = B_FALSE;
1474 
1475         ASSERT(dr->dr_txg == txg);
1476         if (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC ||
1477             dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
1478                 /*
1479                  * We have already issued a sync write for this buffer,
1480                  * or this buffer has already been synced.  It could not
1481                  * have been dirtied since, or we would have cleared the state.
1482                  */
1483                 mutex_exit(&db->db_mtx);
1484                 return (SET_ERROR(EALREADY));
1485         }
1486 
1487         ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
1488         dr->dt.dl.dr_override_state = DR_IN_DMU_SYNC;
1489         mutex_exit(&db->db_mtx);
1490 
1491         dsa = kmem_alloc(sizeof (dmu_sync_arg_t), KM_SLEEP);
1492         dsa->dsa_dr = dr;
1493         dsa->dsa_done = done;
1494         dsa->dsa_zgd = zgd;
1495         dsa->dsa_tx = NULL;
1496 
1497         zio_nowait(arc_write(pio, os->os_spa, txg,
1498             bp, dr->dt.dl.dr_data, DBUF_IS_L2CACHEABLE(db),
1499             DBUF_IS_L2COMPRESSIBLE(db), &zp, dmu_sync_ready, dmu_sync_done,
1500             dsa, ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_CANFAIL, &zb));
1501 
1502         return (0);
1503 }
1504 
1505 int
1506 dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size, int ibs,
1507         dmu_tx_t *tx)
1508 {
1509         dnode_t *dn;
1510         int err;
1511 
1512         err = dnode_hold(os, object, FTAG, &dn);
1513         if (err)
1514                 return (err);
1515         err = dnode_set_blksz(dn, size, ibs, tx);
1516         dnode_rele(dn, FTAG);
1517         return (err);
1518 }
1519 
1520 void
1521 dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
1522         dmu_tx_t *tx)
1523 {
1524         dnode_t *dn;
1525 
1526         /* XXX assumes dnode_hold will not get an i/o error */
1527         (void) dnode_hold(os, object, FTAG, &dn);
1528         ASSERT(checksum < ZIO_CHECKSUM_FUNCTIONS);
1529         dn->dn_checksum = checksum;
1530         dnode_setdirty(dn, tx);
1531         dnode_rele(dn, FTAG);
1532 }
1533 
1534 void
1535 dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
1536         dmu_tx_t *tx)
1537 {
1538         dnode_t *dn;
1539 
1540         /* XXX assumes dnode_hold will not get an i/o error */
1541         (void) dnode_hold(os, object, FTAG, &dn);
1542         ASSERT(compress < ZIO_COMPRESS_FUNCTIONS);
1543         dn->dn_compress = compress;
1544         dnode_setdirty(dn, tx);
1545         dnode_rele(dn, FTAG);
1546 }
1547 
1548 int zfs_mdcomp_disable = 0;
1549 
1550 void
1551 dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp, zio_prop_t *zp)
1552 {
1553         dmu_object_type_t type = dn ? dn->dn_type : DMU_OT_OBJSET;
1554         boolean_t ismd = (level > 0 || DMU_OT_IS_METADATA(type) ||
1555             (wp & WP_SPILL));
1556         enum zio_checksum checksum = os->os_checksum;
1557         enum zio_compress compress = os->os_compress;
1558         enum zio_checksum dedup_checksum = os->os_dedup_checksum;
1559         boolean_t dedup = B_FALSE;
1560         boolean_t nopwrite = B_FALSE;
1561         boolean_t dedup_verify = os->os_dedup_verify;
1562         int copies = os->os_copies;
1563 
1564         /*
1565          * We maintain different write policies for each of the following
1566          * types of data:
1567          *       1. metadata
1568          *       2. preallocated blocks (i.e. level-0 blocks of a dump device)
1569          *       3. all other level 0 blocks
1570          */
1571         if (ismd) {
1572                 /*
1573                  * XXX -- we should design a compression algorithm
1574                  * that specializes in arrays of bps.
1575                  */
1576                 compress = zfs_mdcomp_disable ? ZIO_COMPRESS_EMPTY :
1577                     ZIO_COMPRESS_LZJB;
1578 
1579                 /*
1580                  * Metadata always gets checksummed.  If the data
1581                  * checksum is multi-bit correctable, and it's not a
1582                  * ZBT-style checksum, then it's suitable for metadata
1583                  * as well.  Otherwise, the metadata checksum defaults
1584                  * to fletcher4.
1585                  */
1586                 if (zio_checksum_table[checksum].ci_correctable < 1 ||
1587                     zio_checksum_table[checksum].ci_eck)
1588                         checksum = ZIO_CHECKSUM_FLETCHER_4;
1589         } else if (wp & WP_NOFILL) {
1590                 ASSERT(level == 0);
1591 
1592                 /*
1593                  * If we're writing preallocated blocks, we aren't actually
1594                  * writing them so don't set any policy properties.  These
1595                  * blocks are currently only used by an external subsystem
1596                  * outside of zfs (i.e. dump) and not written by the zio
1597                  * pipeline.
1598                  */
1599                 compress = ZIO_COMPRESS_OFF;
1600                 checksum = ZIO_CHECKSUM_OFF;
1601         } else {
1602                 compress = zio_compress_select(dn->dn_compress, compress);
1603 
1604                 checksum = (dedup_checksum == ZIO_CHECKSUM_OFF) ?
1605                     zio_checksum_select(dn->dn_checksum, checksum) :
1606                     dedup_checksum;
1607 
1608                 /*
1609                  * Determine dedup setting.  If we are in dmu_sync(),
1610                  * we won't actually dedup now because that's all
1611                  * done in syncing context; but we do want to use the
1612                  * dedup checkum.  If the checksum is not strong
1613                  * enough to ensure unique signatures, force
1614                  * dedup_verify.
1615                  */
1616                 if (dedup_checksum != ZIO_CHECKSUM_OFF) {
1617                         dedup = (wp & WP_DMU_SYNC) ? B_FALSE : B_TRUE;
1618                         if (!zio_checksum_table[checksum].ci_dedup)
1619                                 dedup_verify = B_TRUE;
1620                 }
1621 
1622                 /*
1623                  * Enable nopwrite if we have a cryptographically secure
1624                  * checksum that has no known collisions (i.e. SHA-256)
1625                  * and compression is enabled.  We don't enable nopwrite if
1626                  * dedup is enabled as the two features are mutually exclusive.
1627                  */
1628                 nopwrite = (!dedup && zio_checksum_table[checksum].ci_dedup &&
1629                     compress != ZIO_COMPRESS_OFF && zfs_nopwrite_enabled);
1630         }
1631 
1632         zp->zp_checksum = checksum;
1633         zp->zp_compress = compress;
1634         zp->zp_type = (wp & WP_SPILL) ? dn->dn_bonustype : type;
1635         zp->zp_level = level;
1636         zp->zp_copies = MIN(copies + ismd, spa_max_replication(os->os_spa));
1637         zp->zp_dedup = dedup;
1638         zp->zp_dedup_verify = dedup && dedup_verify;
1639         zp->zp_nopwrite = nopwrite;
1640 }
1641 
1642 int
1643 dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole, uint64_t *off)
1644 {
1645         dnode_t *dn;
1646         int i, err;
1647 
1648         err = dnode_hold(os, object, FTAG, &dn);
1649         if (err)
1650                 return (err);
1651         /*
1652          * Sync any current changes before
1653          * we go trundling through the block pointers.
1654          */
1655         for (i = 0; i < TXG_SIZE; i++) {
1656                 if (list_link_active(&dn->dn_dirty_link[i]))
1657                         break;
1658         }
1659         if (i != TXG_SIZE) {
1660                 dnode_rele(dn, FTAG);
1661                 txg_wait_synced(dmu_objset_pool(os), 0);
1662                 err = dnode_hold(os, object, FTAG, &dn);
1663                 if (err)
1664                         return (err);
1665         }
1666 
1667         err = dnode_next_offset(dn, (hole ? DNODE_FIND_HOLE : 0), off, 1, 1, 0);
1668         dnode_rele(dn, FTAG);
1669 
1670         return (err);
1671 }
1672 
1673 void
1674 dmu_object_info_from_dnode(dnode_t *dn, dmu_object_info_t *doi)
1675 {
1676         dnode_phys_t *dnp;
1677 
1678         rw_enter(&dn->dn_struct_rwlock, RW_READER);
1679         mutex_enter(&dn->dn_mtx);
1680 
1681         dnp = dn->dn_phys;
1682 
1683         doi->doi_data_block_size = dn->dn_datablksz;
1684         doi->doi_metadata_block_size = dn->dn_indblkshift ?
1685             1ULL << dn->dn_indblkshift : 0;
1686         doi->doi_type = dn->dn_type;
1687         doi->doi_bonus_type = dn->dn_bonustype;
1688         doi->doi_bonus_size = dn->dn_bonuslen;
1689         doi->doi_indirection = dn->dn_nlevels;
1690         doi->doi_checksum = dn->dn_checksum;
1691         doi->doi_compress = dn->dn_compress;
1692         doi->doi_physical_blocks_512 = (DN_USED_BYTES(dnp) + 256) >> 9;
1693         doi->doi_max_offset = (dn->dn_maxblkid + 1) * dn->dn_datablksz;
1694         doi->doi_fill_count = 0;
1695         for (int i = 0; i < dnp->dn_nblkptr; i++)
1696                 doi->doi_fill_count += dnp->dn_blkptr[i].blk_fill;
1697 
1698         mutex_exit(&dn->dn_mtx);
1699         rw_exit(&dn->dn_struct_rwlock);
1700 }
1701 
1702 /*
1703  * Get information on a DMU object.
1704  * If doi is NULL, just indicates whether the object exists.
1705  */
1706 int
1707 dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi)
1708 {
1709         dnode_t *dn;
1710         int err = dnode_hold(os, object, FTAG, &dn);
1711 
1712         if (err)
1713                 return (err);
1714 
1715         if (doi != NULL)
1716                 dmu_object_info_from_dnode(dn, doi);
1717 
1718         dnode_rele(dn, FTAG);
1719         return (0);
1720 }
1721 
1722 /*
1723  * As above, but faster; can be used when you have a held dbuf in hand.
1724  */
1725 void
1726 dmu_object_info_from_db(dmu_buf_t *db_fake, dmu_object_info_t *doi)
1727 {
1728         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1729 
1730         DB_DNODE_ENTER(db);
1731         dmu_object_info_from_dnode(DB_DNODE(db), doi);
1732         DB_DNODE_EXIT(db);
1733 }
1734 
1735 /*
1736  * Faster still when you only care about the size.
1737  * This is specifically optimized for zfs_getattr().
1738  */
1739 void
1740 dmu_object_size_from_db(dmu_buf_t *db_fake, uint32_t *blksize,
1741     u_longlong_t *nblk512)
1742 {
1743         dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1744         dnode_t *dn;
1745 
1746         DB_DNODE_ENTER(db);
1747         dn = DB_DNODE(db);
1748 
1749         *blksize = dn->dn_datablksz;
1750         /* add 1 for dnode space */
1751         *nblk512 = ((DN_USED_BYTES(dn->dn_phys) + SPA_MINBLOCKSIZE/2) >>
1752             SPA_MINBLOCKSHIFT) + 1;
1753         DB_DNODE_EXIT(db);
1754 }
1755 
1756 void
1757 byteswap_uint64_array(void *vbuf, size_t size)
1758 {
1759         uint64_t *buf = vbuf;
1760         size_t count = size >> 3;
1761         int i;
1762 
1763         ASSERT((size & 7) == 0);
1764 
1765         for (i = 0; i < count; i++)
1766                 buf[i] = BSWAP_64(buf[i]);
1767 }
1768 
1769 void
1770 byteswap_uint32_array(void *vbuf, size_t size)
1771 {
1772         uint32_t *buf = vbuf;
1773         size_t count = size >> 2;
1774         int i;
1775 
1776         ASSERT((size & 3) == 0);
1777 
1778         for (i = 0; i < count; i++)
1779                 buf[i] = BSWAP_32(buf[i]);
1780 }
1781 
1782 void
1783 byteswap_uint16_array(void *vbuf, size_t size)
1784 {
1785         uint16_t *buf = vbuf;
1786         size_t count = size >> 1;
1787         int i;
1788 
1789         ASSERT((size & 1) == 0);
1790 
1791         for (i = 0; i < count; i++)
1792                 buf[i] = BSWAP_16(buf[i]);
1793 }
1794 
1795 /* ARGSUSED */
1796 void
1797 byteswap_uint8_array(void *vbuf, size_t size)
1798 {
1799 }
1800 
1801 void
1802 dmu_init(void)
1803 {
1804         zfs_dbgmsg_init();
1805         sa_cache_init();
1806         xuio_stat_init();
1807         dmu_objset_init();
1808         dnode_init();
1809         dbuf_init();
1810         zfetch_init();
1811         l2arc_init();
1812         arc_init();
1813 }
1814 
1815 void
1816 dmu_fini(void)
1817 {
1818         arc_fini(); /* arc depends on l2arc, so arc must go first */
1819         l2arc_fini();
1820         zfetch_fini();
1821         dbuf_fini();
1822         dnode_fini();
1823         dmu_objset_fini();
1824         xuio_stat_fini();
1825         sa_cache_fini();
1826         zfs_dbgmsg_fini();
1827 }