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 2011 Nexenta Systems, Inc. All rights reserved. 24 * Copyright (c) 2012 by Delphix. All rights reserved. 25 * Copyright (c) 2013, Joyent, Inc. All rights reserved. 26 */ 27 28 #include <sys/zfs_context.h> 29 #include <sys/dmu.h> 30 #include <sys/dmu_impl.h> 31 #include <sys/dbuf.h> 32 #include <sys/dmu_objset.h> 33 #include <sys/dsl_dataset.h> 34 #include <sys/dsl_dir.h> 35 #include <sys/dmu_tx.h> 36 #include <sys/spa.h> 37 #include <sys/zio.h> 38 #include <sys/dmu_zfetch.h> 39 #include <sys/sa.h> 40 #include <sys/sa_impl.h> 41 42 static void dbuf_destroy(dmu_buf_impl_t *db); 43 static int dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx); 44 static void dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx); 45 46 /* 47 * Global data structures and functions for the dbuf cache. 48 */ 49 static kmem_cache_t *dbuf_cache; 50 51 /* ARGSUSED */ 52 static int 53 dbuf_cons(void *vdb, void *unused, int kmflag) 54 { 55 dmu_buf_impl_t *db = vdb; 56 bzero(db, sizeof (dmu_buf_impl_t)); 57 58 mutex_init(&db->db_mtx, NULL, MUTEX_DEFAULT, NULL); 59 cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL); 60 refcount_create(&db->db_holds); 61 return (0); 62 } 63 64 /* ARGSUSED */ 65 static void 66 dbuf_dest(void *vdb, void *unused) 67 { 68 dmu_buf_impl_t *db = vdb; 69 mutex_destroy(&db->db_mtx); 70 cv_destroy(&db->db_changed); 71 refcount_destroy(&db->db_holds); 72 } 73 74 /* 75 * dbuf hash table routines 76 */ 77 static dbuf_hash_table_t dbuf_hash_table; 78 79 static uint64_t dbuf_hash_count; 80 81 static uint64_t 82 dbuf_hash(void *os, uint64_t obj, uint8_t lvl, uint64_t blkid) 83 { 84 uintptr_t osv = (uintptr_t)os; 85 uint64_t crc = -1ULL; 86 87 ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY); 88 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (lvl)) & 0xFF]; 89 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (osv >> 6)) & 0xFF]; 90 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 0)) & 0xFF]; 91 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 8)) & 0xFF]; 92 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 0)) & 0xFF]; 93 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 8)) & 0xFF]; 94 95 crc ^= (osv>>14) ^ (obj>>16) ^ (blkid>>16); 96 97 return (crc); 98 } 99 100 #define DBUF_HASH(os, obj, level, blkid) dbuf_hash(os, obj, level, blkid); 101 102 #define DBUF_EQUAL(dbuf, os, obj, level, blkid) \ 103 ((dbuf)->db.db_object == (obj) && \ 104 (dbuf)->db_objset == (os) && \ 105 (dbuf)->db_level == (level) && \ 106 (dbuf)->db_blkid == (blkid)) 107 108 dmu_buf_impl_t * 109 dbuf_find(dnode_t *dn, uint8_t level, uint64_t blkid) 110 { 111 dbuf_hash_table_t *h = &dbuf_hash_table; 112 objset_t *os = dn->dn_objset; 113 uint64_t obj = dn->dn_object; 114 uint64_t hv = DBUF_HASH(os, obj, level, blkid); 115 uint64_t idx = hv & h->hash_table_mask; 116 dmu_buf_impl_t *db; 117 118 mutex_enter(DBUF_HASH_MUTEX(h, idx)); 119 for (db = h->hash_table[idx]; db != NULL; db = db->db_hash_next) { 120 if (DBUF_EQUAL(db, os, obj, level, blkid)) { 121 mutex_enter(&db->db_mtx); 122 if (db->db_state != DB_EVICTING) { 123 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 124 return (db); 125 } 126 mutex_exit(&db->db_mtx); 127 } 128 } 129 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 130 return (NULL); 131 } 132 133 /* 134 * Insert an entry into the hash table. If there is already an element 135 * equal to elem in the hash table, then the already existing element 136 * will be returned and the new element will not be inserted. 137 * Otherwise returns NULL. 138 */ 139 static dmu_buf_impl_t * 140 dbuf_hash_insert(dmu_buf_impl_t *db) 141 { 142 dbuf_hash_table_t *h = &dbuf_hash_table; 143 objset_t *os = db->db_objset; 144 uint64_t obj = db->db.db_object; 145 int level = db->db_level; 146 uint64_t blkid = db->db_blkid; 147 uint64_t hv = DBUF_HASH(os, obj, level, blkid); 148 uint64_t idx = hv & h->hash_table_mask; 149 dmu_buf_impl_t *dbf; 150 151 mutex_enter(DBUF_HASH_MUTEX(h, idx)); 152 for (dbf = h->hash_table[idx]; dbf != NULL; dbf = dbf->db_hash_next) { 153 if (DBUF_EQUAL(dbf, os, obj, level, blkid)) { 154 mutex_enter(&dbf->db_mtx); 155 if (dbf->db_state != DB_EVICTING) { 156 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 157 return (dbf); 158 } 159 mutex_exit(&dbf->db_mtx); 160 } 161 } 162 163 mutex_enter(&db->db_mtx); 164 db->db_hash_next = h->hash_table[idx]; 165 h->hash_table[idx] = db; 166 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 167 atomic_add_64(&dbuf_hash_count, 1); 168 169 return (NULL); 170 } 171 172 /* 173 * Remove an entry from the hash table. This operation will 174 * fail if there are any existing holds on the db. 175 */ 176 static void 177 dbuf_hash_remove(dmu_buf_impl_t *db) 178 { 179 dbuf_hash_table_t *h = &dbuf_hash_table; 180 uint64_t hv = DBUF_HASH(db->db_objset, db->db.db_object, 181 db->db_level, db->db_blkid); 182 uint64_t idx = hv & h->hash_table_mask; 183 dmu_buf_impl_t *dbf, **dbp; 184 185 /* 186 * We musn't hold db_mtx to maintin lock ordering: 187 * DBUF_HASH_MUTEX > db_mtx. 188 */ 189 ASSERT(refcount_is_zero(&db->db_holds)); 190 ASSERT(db->db_state == DB_EVICTING); 191 ASSERT(!MUTEX_HELD(&db->db_mtx)); 192 193 mutex_enter(DBUF_HASH_MUTEX(h, idx)); 194 dbp = &h->hash_table[idx]; 195 while ((dbf = *dbp) != db) { 196 dbp = &dbf->db_hash_next; 197 ASSERT(dbf != NULL); 198 } 199 *dbp = db->db_hash_next; 200 db->db_hash_next = NULL; 201 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 202 atomic_add_64(&dbuf_hash_count, -1); 203 } 204 205 static arc_evict_func_t dbuf_do_evict; 206 207 static void 208 dbuf_evict_user(dmu_buf_impl_t *db) 209 { 210 ASSERT(MUTEX_HELD(&db->db_mtx)); 211 212 if (db->db_level != 0 || db->db_evict_func == NULL) 213 return; 214 215 if (db->db_user_data_ptr_ptr) 216 *db->db_user_data_ptr_ptr = db->db.db_data; 217 db->db_evict_func(&db->db, db->db_user_ptr); 218 db->db_user_ptr = NULL; 219 db->db_user_data_ptr_ptr = NULL; 220 db->db_evict_func = NULL; 221 } 222 223 boolean_t 224 dbuf_is_metadata(dmu_buf_impl_t *db) 225 { 226 if (db->db_level > 0) { 227 return (B_TRUE); 228 } else { 229 boolean_t is_metadata; 230 231 DB_DNODE_ENTER(db); 232 is_metadata = DMU_OT_IS_METADATA(DB_DNODE(db)->dn_type); 233 DB_DNODE_EXIT(db); 234 235 return (is_metadata); 236 } 237 } 238 239 void 240 dbuf_evict(dmu_buf_impl_t *db) 241 { 242 ASSERT(MUTEX_HELD(&db->db_mtx)); 243 ASSERT(db->db_buf == NULL); 244 ASSERT(db->db_data_pending == NULL); 245 246 dbuf_clear(db); 247 dbuf_destroy(db); 248 } 249 250 void 251 dbuf_init(void) 252 { 253 uint64_t hsize = 1ULL << 16; 254 dbuf_hash_table_t *h = &dbuf_hash_table; 255 int i; 256 257 /* 258 * The hash table is big enough to fill all of physical memory 259 * with an average 4K block size. The table will take up 260 * totalmem*sizeof(void*)/4K (i.e. 2MB/GB with 8-byte pointers). 261 */ 262 while (hsize * 4096 < physmem * PAGESIZE) 263 hsize <<= 1; 264 265 retry: 266 h->hash_table_mask = hsize - 1; 267 h->hash_table = kmem_zalloc(hsize * sizeof (void *), KM_NOSLEEP); 268 if (h->hash_table == NULL) { 269 /* XXX - we should really return an error instead of assert */ 270 ASSERT(hsize > (1ULL << 10)); 271 hsize >>= 1; 272 goto retry; 273 } 274 275 dbuf_cache = kmem_cache_create("dmu_buf_impl_t", 276 sizeof (dmu_buf_impl_t), 277 0, dbuf_cons, dbuf_dest, NULL, NULL, NULL, 0); 278 279 for (i = 0; i < DBUF_MUTEXES; i++) 280 mutex_init(&h->hash_mutexes[i], NULL, MUTEX_DEFAULT, NULL); 281 } 282 283 void 284 dbuf_fini(void) 285 { 286 dbuf_hash_table_t *h = &dbuf_hash_table; 287 int i; 288 289 for (i = 0; i < DBUF_MUTEXES; i++) 290 mutex_destroy(&h->hash_mutexes[i]); 291 kmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *)); 292 kmem_cache_destroy(dbuf_cache); 293 } 294 295 /* 296 * Other stuff. 297 */ 298 299 #ifdef ZFS_DEBUG 300 static void 301 dbuf_verify(dmu_buf_impl_t *db) 302 { 303 dnode_t *dn; 304 dbuf_dirty_record_t *dr; 305 306 ASSERT(MUTEX_HELD(&db->db_mtx)); 307 308 if (!(zfs_flags & ZFS_DEBUG_DBUF_VERIFY)) 309 return; 310 311 ASSERT(db->db_objset != NULL); 312 DB_DNODE_ENTER(db); 313 dn = DB_DNODE(db); 314 if (dn == NULL) { 315 ASSERT(db->db_parent == NULL); 316 ASSERT(db->db_blkptr == NULL); 317 } else { 318 ASSERT3U(db->db.db_object, ==, dn->dn_object); 319 ASSERT3P(db->db_objset, ==, dn->dn_objset); 320 ASSERT3U(db->db_level, <, dn->dn_nlevels); 321 ASSERT(db->db_blkid == DMU_BONUS_BLKID || 322 db->db_blkid == DMU_SPILL_BLKID || 323 !list_is_empty(&dn->dn_dbufs)); 324 } 325 if (db->db_blkid == DMU_BONUS_BLKID) { 326 ASSERT(dn != NULL); 327 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen); 328 ASSERT3U(db->db.db_offset, ==, DMU_BONUS_BLKID); 329 } else if (db->db_blkid == DMU_SPILL_BLKID) { 330 ASSERT(dn != NULL); 331 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen); 332 ASSERT0(db->db.db_offset); 333 } else { 334 ASSERT3U(db->db.db_offset, ==, db->db_blkid * db->db.db_size); 335 } 336 337 for (dr = db->db_data_pending; dr != NULL; dr = dr->dr_next) 338 ASSERT(dr->dr_dbuf == db); 339 340 for (dr = db->db_last_dirty; dr != NULL; dr = dr->dr_next) 341 ASSERT(dr->dr_dbuf == db); 342 343 /* 344 * We can't assert that db_size matches dn_datablksz because it 345 * can be momentarily different when another thread is doing 346 * dnode_set_blksz(). 347 */ 348 if (db->db_level == 0 && db->db.db_object == DMU_META_DNODE_OBJECT) { 349 dr = db->db_data_pending; 350 /* 351 * It should only be modified in syncing context, so 352 * make sure we only have one copy of the data. 353 */ 354 ASSERT(dr == NULL || dr->dt.dl.dr_data == db->db_buf); 355 } 356 357 /* verify db->db_blkptr */ 358 if (db->db_blkptr) { 359 if (db->db_parent == dn->dn_dbuf) { 360 /* db is pointed to by the dnode */ 361 /* ASSERT3U(db->db_blkid, <, dn->dn_nblkptr); */ 362 if (DMU_OBJECT_IS_SPECIAL(db->db.db_object)) 363 ASSERT(db->db_parent == NULL); 364 else 365 ASSERT(db->db_parent != NULL); 366 if (db->db_blkid != DMU_SPILL_BLKID) 367 ASSERT3P(db->db_blkptr, ==, 368 &dn->dn_phys->dn_blkptr[db->db_blkid]); 369 } else { 370 /* db is pointed to by an indirect block */ 371 int epb = db->db_parent->db.db_size >> SPA_BLKPTRSHIFT; 372 ASSERT3U(db->db_parent->db_level, ==, db->db_level+1); 373 ASSERT3U(db->db_parent->db.db_object, ==, 374 db->db.db_object); 375 /* 376 * dnode_grow_indblksz() can make this fail if we don't 377 * have the struct_rwlock. XXX indblksz no longer 378 * grows. safe to do this now? 379 */ 380 if (RW_WRITE_HELD(&dn->dn_struct_rwlock)) { 381 ASSERT3P(db->db_blkptr, ==, 382 ((blkptr_t *)db->db_parent->db.db_data + 383 db->db_blkid % epb)); 384 } 385 } 386 } 387 if ((db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr)) && 388 (db->db_buf == NULL || db->db_buf->b_data) && 389 db->db.db_data && db->db_blkid != DMU_BONUS_BLKID && 390 db->db_state != DB_FILL && !dn->dn_free_txg) { 391 /* 392 * If the blkptr isn't set but they have nonzero data, 393 * it had better be dirty, otherwise we'll lose that 394 * data when we evict this buffer. 395 */ 396 if (db->db_dirtycnt == 0) { 397 uint64_t *buf = db->db.db_data; 398 int i; 399 400 for (i = 0; i < db->db.db_size >> 3; i++) { 401 ASSERT(buf[i] == 0); 402 } 403 } 404 } 405 DB_DNODE_EXIT(db); 406 } 407 #endif 408 409 static void 410 dbuf_update_data(dmu_buf_impl_t *db) 411 { 412 ASSERT(MUTEX_HELD(&db->db_mtx)); 413 if (db->db_level == 0 && db->db_user_data_ptr_ptr) { 414 ASSERT(!refcount_is_zero(&db->db_holds)); 415 *db->db_user_data_ptr_ptr = db->db.db_data; 416 } 417 } 418 419 static void 420 dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf) 421 { 422 ASSERT(MUTEX_HELD(&db->db_mtx)); 423 ASSERT(db->db_buf == NULL || !arc_has_callback(db->db_buf)); 424 db->db_buf = buf; 425 if (buf != NULL) { 426 ASSERT(buf->b_data != NULL); 427 db->db.db_data = buf->b_data; 428 if (!arc_released(buf)) 429 arc_set_callback(buf, dbuf_do_evict, db); 430 dbuf_update_data(db); 431 } else { 432 dbuf_evict_user(db); 433 db->db.db_data = NULL; 434 if (db->db_state != DB_NOFILL) 435 db->db_state = DB_UNCACHED; 436 } 437 } 438 439 /* 440 * Loan out an arc_buf for read. Return the loaned arc_buf. 441 */ 442 arc_buf_t * 443 dbuf_loan_arcbuf(dmu_buf_impl_t *db) 444 { 445 arc_buf_t *abuf; 446 447 mutex_enter(&db->db_mtx); 448 if (arc_released(db->db_buf) || refcount_count(&db->db_holds) > 1) { 449 int blksz = db->db.db_size; 450 spa_t *spa; 451 452 mutex_exit(&db->db_mtx); 453 DB_GET_SPA(&spa, db); 454 abuf = arc_loan_buf(spa, blksz); 455 bcopy(db->db.db_data, abuf->b_data, blksz); 456 } else { 457 abuf = db->db_buf; 458 arc_loan_inuse_buf(abuf, db); 459 dbuf_set_data(db, NULL); 460 mutex_exit(&db->db_mtx); 461 } 462 return (abuf); 463 } 464 465 uint64_t 466 dbuf_whichblock(dnode_t *dn, uint64_t offset) 467 { 468 if (dn->dn_datablkshift) { 469 return (offset >> dn->dn_datablkshift); 470 } else { 471 ASSERT3U(offset, <, dn->dn_datablksz); 472 return (0); 473 } 474 } 475 476 static void 477 dbuf_read_done(zio_t *zio, arc_buf_t *buf, void *vdb) 478 { 479 dmu_buf_impl_t *db = vdb; 480 481 mutex_enter(&db->db_mtx); 482 ASSERT3U(db->db_state, ==, DB_READ); 483 /* 484 * All reads are synchronous, so we must have a hold on the dbuf 485 */ 486 ASSERT(refcount_count(&db->db_holds) > 0); 487 ASSERT(db->db_buf == NULL); 488 ASSERT(db->db.db_data == NULL); 489 if (db->db_level == 0 && db->db_freed_in_flight) { 490 /* we were freed in flight; disregard any error */ 491 arc_release(buf, db); 492 bzero(buf->b_data, db->db.db_size); 493 arc_buf_freeze(buf); 494 db->db_freed_in_flight = FALSE; 495 dbuf_set_data(db, buf); 496 db->db_state = DB_CACHED; 497 } else if (zio == NULL || zio->io_error == 0) { 498 dbuf_set_data(db, buf); 499 db->db_state = DB_CACHED; 500 } else { 501 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 502 ASSERT3P(db->db_buf, ==, NULL); 503 VERIFY(arc_buf_remove_ref(buf, db) == 1); 504 db->db_state = DB_UNCACHED; 505 } 506 cv_broadcast(&db->db_changed); 507 dbuf_rele_and_unlock(db, NULL); 508 } 509 510 static void 511 dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t *flags) 512 { 513 dnode_t *dn; 514 spa_t *spa; 515 zbookmark_t zb; 516 uint32_t aflags = ARC_NOWAIT; 517 arc_buf_t *pbuf; 518 519 DB_DNODE_ENTER(db); 520 dn = DB_DNODE(db); 521 ASSERT(!refcount_is_zero(&db->db_holds)); 522 /* We need the struct_rwlock to prevent db_blkptr from changing. */ 523 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 524 ASSERT(MUTEX_HELD(&db->db_mtx)); 525 ASSERT(db->db_state == DB_UNCACHED); 526 ASSERT(db->db_buf == NULL); 527 528 if (db->db_blkid == DMU_BONUS_BLKID) { 529 int bonuslen = MIN(dn->dn_bonuslen, dn->dn_phys->dn_bonuslen); 530 531 ASSERT3U(bonuslen, <=, db->db.db_size); 532 db->db.db_data = zio_buf_alloc(DN_MAX_BONUSLEN); 533 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER); 534 if (bonuslen < DN_MAX_BONUSLEN) 535 bzero(db->db.db_data, DN_MAX_BONUSLEN); 536 537 if (bonuslen) { 538 /* 539 * Absent byzantine on-disk corruption, we fully expect 540 * our bonuslen to be no more than DN_MAX_BONUSLEN -- 541 * but we nonetheless explicitly clamp it on the bcopy() 542 * to prevent any on-disk corruption from becoming 543 * rampant in-kernel corruption. 544 */ 545 bcopy(DN_BONUS(dn->dn_phys), db->db.db_data, 546 MIN(bonuslen, DN_MAX_BONUSLEN)); 547 } 548 549 DB_DNODE_EXIT(db); 550 dbuf_update_data(db); 551 db->db_state = DB_CACHED; 552 mutex_exit(&db->db_mtx); 553 return; 554 } 555 556 /* 557 * Recheck BP_IS_HOLE() after dnode_block_freed() in case dnode_sync() 558 * processes the delete record and clears the bp while we are waiting 559 * for the dn_mtx (resulting in a "no" from block_freed). 560 */ 561 if (db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr) || 562 (db->db_level == 0 && (dnode_block_freed(dn, db->db_blkid) || 563 BP_IS_HOLE(db->db_blkptr)))) { 564 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 565 566 dbuf_set_data(db, arc_buf_alloc(dn->dn_objset->os_spa, 567 db->db.db_size, db, type)); 568 DB_DNODE_EXIT(db); 569 bzero(db->db.db_data, db->db.db_size); 570 db->db_state = DB_CACHED; 571 *flags |= DB_RF_CACHED; 572 mutex_exit(&db->db_mtx); 573 return; 574 } 575 576 spa = dn->dn_objset->os_spa; 577 DB_DNODE_EXIT(db); 578 579 db->db_state = DB_READ; 580 mutex_exit(&db->db_mtx); 581 582 if (DBUF_IS_L2CACHEABLE(db)) 583 aflags |= ARC_L2CACHE; 584 585 SET_BOOKMARK(&zb, db->db_objset->os_dsl_dataset ? 586 db->db_objset->os_dsl_dataset->ds_object : DMU_META_OBJSET, 587 db->db.db_object, db->db_level, db->db_blkid); 588 589 dbuf_add_ref(db, NULL); 590 /* ZIO_FLAG_CANFAIL callers have to check the parent zio's error */ 591 592 if (db->db_parent) 593 pbuf = db->db_parent->db_buf; 594 else 595 pbuf = db->db_objset->os_phys_buf; 596 597 (void) dsl_read(zio, spa, db->db_blkptr, pbuf, 598 dbuf_read_done, db, ZIO_PRIORITY_SYNC_READ, 599 (*flags & DB_RF_CANFAIL) ? ZIO_FLAG_CANFAIL : ZIO_FLAG_MUSTSUCCEED, 600 &aflags, &zb); 601 if (aflags & ARC_CACHED) 602 *flags |= DB_RF_CACHED; 603 } 604 605 int 606 dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags) 607 { 608 int err = 0; 609 int havepzio = (zio != NULL); 610 int prefetch; 611 dnode_t *dn; 612 613 /* 614 * We don't have to hold the mutex to check db_state because it 615 * can't be freed while we have a hold on the buffer. 616 */ 617 ASSERT(!refcount_is_zero(&db->db_holds)); 618 619 if (db->db_state == DB_NOFILL) 620 return (EIO); 621 622 DB_DNODE_ENTER(db); 623 dn = DB_DNODE(db); 624 if ((flags & DB_RF_HAVESTRUCT) == 0) 625 rw_enter(&dn->dn_struct_rwlock, RW_READER); 626 627 prefetch = db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID && 628 (flags & DB_RF_NOPREFETCH) == 0 && dn != NULL && 629 DBUF_IS_CACHEABLE(db); 630 631 mutex_enter(&db->db_mtx); 632 if (db->db_state == DB_CACHED) { 633 mutex_exit(&db->db_mtx); 634 if (prefetch) 635 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset, 636 db->db.db_size, TRUE); 637 if ((flags & DB_RF_HAVESTRUCT) == 0) 638 rw_exit(&dn->dn_struct_rwlock); 639 DB_DNODE_EXIT(db); 640 } else if (db->db_state == DB_UNCACHED) { 641 spa_t *spa = dn->dn_objset->os_spa; 642 643 if (zio == NULL) 644 zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL); 645 dbuf_read_impl(db, zio, &flags); 646 647 /* dbuf_read_impl has dropped db_mtx for us */ 648 649 if (prefetch) 650 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset, 651 db->db.db_size, flags & DB_RF_CACHED); 652 653 if ((flags & DB_RF_HAVESTRUCT) == 0) 654 rw_exit(&dn->dn_struct_rwlock); 655 DB_DNODE_EXIT(db); 656 657 if (!havepzio) 658 err = zio_wait(zio); 659 } else { 660 mutex_exit(&db->db_mtx); 661 if (prefetch) 662 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset, 663 db->db.db_size, TRUE); 664 if ((flags & DB_RF_HAVESTRUCT) == 0) 665 rw_exit(&dn->dn_struct_rwlock); 666 DB_DNODE_EXIT(db); 667 668 mutex_enter(&db->db_mtx); 669 if ((flags & DB_RF_NEVERWAIT) == 0) { 670 while (db->db_state == DB_READ || 671 db->db_state == DB_FILL) { 672 ASSERT(db->db_state == DB_READ || 673 (flags & DB_RF_HAVESTRUCT) == 0); 674 cv_wait(&db->db_changed, &db->db_mtx); 675 } 676 if (db->db_state == DB_UNCACHED) 677 err = EIO; 678 } 679 mutex_exit(&db->db_mtx); 680 } 681 682 ASSERT(err || havepzio || db->db_state == DB_CACHED); 683 return (err); 684 } 685 686 static void 687 dbuf_noread(dmu_buf_impl_t *db) 688 { 689 ASSERT(!refcount_is_zero(&db->db_holds)); 690 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 691 mutex_enter(&db->db_mtx); 692 while (db->db_state == DB_READ || db->db_state == DB_FILL) 693 cv_wait(&db->db_changed, &db->db_mtx); 694 if (db->db_state == DB_UNCACHED) { 695 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 696 spa_t *spa; 697 698 ASSERT(db->db_buf == NULL); 699 ASSERT(db->db.db_data == NULL); 700 DB_GET_SPA(&spa, db); 701 dbuf_set_data(db, arc_buf_alloc(spa, db->db.db_size, db, type)); 702 db->db_state = DB_FILL; 703 } else if (db->db_state == DB_NOFILL) { 704 dbuf_set_data(db, NULL); 705 } else { 706 ASSERT3U(db->db_state, ==, DB_CACHED); 707 } 708 mutex_exit(&db->db_mtx); 709 } 710 711 /* 712 * This is our just-in-time copy function. It makes a copy of 713 * buffers, that have been modified in a previous transaction 714 * group, before we modify them in the current active group. 715 * 716 * This function is used in two places: when we are dirtying a 717 * buffer for the first time in a txg, and when we are freeing 718 * a range in a dnode that includes this buffer. 719 * 720 * Note that when we are called from dbuf_free_range() we do 721 * not put a hold on the buffer, we just traverse the active 722 * dbuf list for the dnode. 723 */ 724 static void 725 dbuf_fix_old_data(dmu_buf_impl_t *db, uint64_t txg) 726 { 727 dbuf_dirty_record_t *dr = db->db_last_dirty; 728 729 ASSERT(MUTEX_HELD(&db->db_mtx)); 730 ASSERT(db->db.db_data != NULL); 731 ASSERT(db->db_level == 0); 732 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT); 733 734 if (dr == NULL || 735 (dr->dt.dl.dr_data != 736 ((db->db_blkid == DMU_BONUS_BLKID) ? db->db.db_data : db->db_buf))) 737 return; 738 739 /* 740 * If the last dirty record for this dbuf has not yet synced 741 * and its referencing the dbuf data, either: 742 * reset the reference to point to a new copy, 743 * or (if there a no active holders) 744 * just null out the current db_data pointer. 745 */ 746 ASSERT(dr->dr_txg >= txg - 2); 747 if (db->db_blkid == DMU_BONUS_BLKID) { 748 /* Note that the data bufs here are zio_bufs */ 749 dr->dt.dl.dr_data = zio_buf_alloc(DN_MAX_BONUSLEN); 750 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER); 751 bcopy(db->db.db_data, dr->dt.dl.dr_data, DN_MAX_BONUSLEN); 752 } else if (refcount_count(&db->db_holds) > db->db_dirtycnt) { 753 int size = db->db.db_size; 754 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 755 spa_t *spa; 756 757 DB_GET_SPA(&spa, db); 758 dr->dt.dl.dr_data = arc_buf_alloc(spa, size, db, type); 759 bcopy(db->db.db_data, dr->dt.dl.dr_data->b_data, size); 760 } else { 761 dbuf_set_data(db, NULL); 762 } 763 } 764 765 void 766 dbuf_unoverride(dbuf_dirty_record_t *dr) 767 { 768 dmu_buf_impl_t *db = dr->dr_dbuf; 769 blkptr_t *bp = &dr->dt.dl.dr_overridden_by; 770 uint64_t txg = dr->dr_txg; 771 772 ASSERT(MUTEX_HELD(&db->db_mtx)); 773 ASSERT(dr->dt.dl.dr_override_state != DR_IN_DMU_SYNC); 774 ASSERT(db->db_level == 0); 775 776 if (db->db_blkid == DMU_BONUS_BLKID || 777 dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN) 778 return; 779 780 ASSERT(db->db_data_pending != dr); 781 782 /* free this block */ 783 if (!BP_IS_HOLE(bp) && !dr->dt.dl.dr_nopwrite) { 784 spa_t *spa; 785 786 DB_GET_SPA(&spa, db); 787 zio_free(spa, txg, bp); 788 } 789 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN; 790 dr->dt.dl.dr_nopwrite = B_FALSE; 791 792 /* 793 * Release the already-written buffer, so we leave it in 794 * a consistent dirty state. Note that all callers are 795 * modifying the buffer, so they will immediately do 796 * another (redundant) arc_release(). Therefore, leave 797 * the buf thawed to save the effort of freezing & 798 * immediately re-thawing it. 799 */ 800 arc_release(dr->dt.dl.dr_data, db); 801 } 802 803 /* 804 * Evict (if its unreferenced) or clear (if its referenced) any level-0 805 * data blocks in the free range, so that any future readers will find 806 * empty blocks. Also, if we happen accross any level-1 dbufs in the 807 * range that have not already been marked dirty, mark them dirty so 808 * they stay in memory. 809 */ 810 void 811 dbuf_free_range(dnode_t *dn, uint64_t start, uint64_t end, dmu_tx_t *tx) 812 { 813 dmu_buf_impl_t *db, *db_next; 814 uint64_t txg = tx->tx_txg; 815 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT; 816 uint64_t first_l1 = start >> epbs; 817 uint64_t last_l1 = end >> epbs; 818 819 if (end > dn->dn_maxblkid && (end != DMU_SPILL_BLKID)) { 820 end = dn->dn_maxblkid; 821 last_l1 = end >> epbs; 822 } 823 dprintf_dnode(dn, "start=%llu end=%llu\n", start, end); 824 mutex_enter(&dn->dn_dbufs_mtx); 825 for (db = list_head(&dn->dn_dbufs); db; db = db_next) { 826 db_next = list_next(&dn->dn_dbufs, db); 827 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 828 829 if (db->db_level == 1 && 830 db->db_blkid >= first_l1 && db->db_blkid <= last_l1) { 831 mutex_enter(&db->db_mtx); 832 if (db->db_last_dirty && 833 db->db_last_dirty->dr_txg < txg) { 834 dbuf_add_ref(db, FTAG); 835 mutex_exit(&db->db_mtx); 836 dbuf_will_dirty(db, tx); 837 dbuf_rele(db, FTAG); 838 } else { 839 mutex_exit(&db->db_mtx); 840 } 841 } 842 843 if (db->db_level != 0) 844 continue; 845 dprintf_dbuf(db, "found buf %s\n", ""); 846 if (db->db_blkid < start || db->db_blkid > end) 847 continue; 848 849 /* found a level 0 buffer in the range */ 850 if (dbuf_undirty(db, tx)) 851 continue; 852 853 mutex_enter(&db->db_mtx); 854 if (db->db_state == DB_UNCACHED || 855 db->db_state == DB_NOFILL || 856 db->db_state == DB_EVICTING) { 857 ASSERT(db->db.db_data == NULL); 858 mutex_exit(&db->db_mtx); 859 continue; 860 } 861 if (db->db_state == DB_READ || db->db_state == DB_FILL) { 862 /* will be handled in dbuf_read_done or dbuf_rele */ 863 db->db_freed_in_flight = TRUE; 864 mutex_exit(&db->db_mtx); 865 continue; 866 } 867 if (refcount_count(&db->db_holds) == 0) { 868 ASSERT(db->db_buf); 869 dbuf_clear(db); 870 continue; 871 } 872 /* The dbuf is referenced */ 873 874 if (db->db_last_dirty != NULL) { 875 dbuf_dirty_record_t *dr = db->db_last_dirty; 876 877 if (dr->dr_txg == txg) { 878 /* 879 * This buffer is "in-use", re-adjust the file 880 * size to reflect that this buffer may 881 * contain new data when we sync. 882 */ 883 if (db->db_blkid != DMU_SPILL_BLKID && 884 db->db_blkid > dn->dn_maxblkid) 885 dn->dn_maxblkid = db->db_blkid; 886 dbuf_unoverride(dr); 887 } else { 888 /* 889 * This dbuf is not dirty in the open context. 890 * Either uncache it (if its not referenced in 891 * the open context) or reset its contents to 892 * empty. 893 */ 894 dbuf_fix_old_data(db, txg); 895 } 896 } 897 /* clear the contents if its cached */ 898 if (db->db_state == DB_CACHED) { 899 ASSERT(db->db.db_data != NULL); 900 arc_release(db->db_buf, db); 901 bzero(db->db.db_data, db->db.db_size); 902 arc_buf_freeze(db->db_buf); 903 } 904 905 mutex_exit(&db->db_mtx); 906 } 907 mutex_exit(&dn->dn_dbufs_mtx); 908 } 909 910 static int 911 dbuf_block_freeable(dmu_buf_impl_t *db) 912 { 913 dsl_dataset_t *ds = db->db_objset->os_dsl_dataset; 914 uint64_t birth_txg = 0; 915 916 /* 917 * We don't need any locking to protect db_blkptr: 918 * If it's syncing, then db_last_dirty will be set 919 * so we'll ignore db_blkptr. 920 */ 921 ASSERT(MUTEX_HELD(&db->db_mtx)); 922 if (db->db_last_dirty) 923 birth_txg = db->db_last_dirty->dr_txg; 924 else if (db->db_blkptr) 925 birth_txg = db->db_blkptr->blk_birth; 926 927 /* 928 * If we don't exist or are in a snapshot, we can't be freed. 929 * Don't pass the bp to dsl_dataset_block_freeable() since we 930 * are holding the db_mtx lock and might deadlock if we are 931 * prefetching a dedup-ed block. 932 */ 933 if (birth_txg) 934 return (ds == NULL || 935 dsl_dataset_block_freeable(ds, NULL, birth_txg)); 936 else 937 return (FALSE); 938 } 939 940 void 941 dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx) 942 { 943 arc_buf_t *buf, *obuf; 944 int osize = db->db.db_size; 945 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 946 dnode_t *dn; 947 948 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 949 950 DB_DNODE_ENTER(db); 951 dn = DB_DNODE(db); 952 953 /* XXX does *this* func really need the lock? */ 954 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock)); 955 956 /* 957 * This call to dbuf_will_dirty() with the dn_struct_rwlock held 958 * is OK, because there can be no other references to the db 959 * when we are changing its size, so no concurrent DB_FILL can 960 * be happening. 961 */ 962 /* 963 * XXX we should be doing a dbuf_read, checking the return 964 * value and returning that up to our callers 965 */ 966 dbuf_will_dirty(db, tx); 967 968 /* create the data buffer for the new block */ 969 buf = arc_buf_alloc(dn->dn_objset->os_spa, size, db, type); 970 971 /* copy old block data to the new block */ 972 obuf = db->db_buf; 973 bcopy(obuf->b_data, buf->b_data, MIN(osize, size)); 974 /* zero the remainder */ 975 if (size > osize) 976 bzero((uint8_t *)buf->b_data + osize, size - osize); 977 978 mutex_enter(&db->db_mtx); 979 dbuf_set_data(db, buf); 980 VERIFY(arc_buf_remove_ref(obuf, db) == 1); 981 db->db.db_size = size; 982 983 if (db->db_level == 0) { 984 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg); 985 db->db_last_dirty->dt.dl.dr_data = buf; 986 } 987 mutex_exit(&db->db_mtx); 988 989 dnode_willuse_space(dn, size-osize, tx); 990 DB_DNODE_EXIT(db); 991 } 992 993 void 994 dbuf_release_bp(dmu_buf_impl_t *db) 995 { 996 objset_t *os; 997 zbookmark_t zb; 998 999 DB_GET_OBJSET(&os, db); 1000 ASSERT(dsl_pool_sync_context(dmu_objset_pool(os))); 1001 ASSERT(arc_released(os->os_phys_buf) || 1002 list_link_active(&os->os_dsl_dataset->ds_synced_link)); 1003 ASSERT(db->db_parent == NULL || arc_released(db->db_parent->db_buf)); 1004 1005 zb.zb_objset = os->os_dsl_dataset ? 1006 os->os_dsl_dataset->ds_object : 0; 1007 zb.zb_object = db->db.db_object; 1008 zb.zb_level = db->db_level; 1009 zb.zb_blkid = db->db_blkid; 1010 (void) arc_release_bp(db->db_buf, db, 1011 db->db_blkptr, os->os_spa, &zb); 1012 } 1013 1014 dbuf_dirty_record_t * 1015 dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx) 1016 { 1017 dnode_t *dn; 1018 objset_t *os; 1019 dbuf_dirty_record_t **drp, *dr; 1020 int drop_struct_lock = FALSE; 1021 boolean_t do_free_accounting = B_FALSE; 1022 int txgoff = tx->tx_txg & TXG_MASK; 1023 1024 ASSERT(tx->tx_txg != 0); 1025 ASSERT(!refcount_is_zero(&db->db_holds)); 1026 DMU_TX_DIRTY_BUF(tx, db); 1027 1028 DB_DNODE_ENTER(db); 1029 dn = DB_DNODE(db); 1030 /* 1031 * Shouldn't dirty a regular buffer in syncing context. Private 1032 * objects may be dirtied in syncing context, but only if they 1033 * were already pre-dirtied in open context. 1034 */ 1035 ASSERT(!dmu_tx_is_syncing(tx) || 1036 BP_IS_HOLE(dn->dn_objset->os_rootbp) || 1037 DMU_OBJECT_IS_SPECIAL(dn->dn_object) || 1038 dn->dn_objset->os_dsl_dataset == NULL); 1039 /* 1040 * We make this assert for private objects as well, but after we 1041 * check if we're already dirty. They are allowed to re-dirty 1042 * in syncing context. 1043 */ 1044 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT || 1045 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx == 1046 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN)); 1047 1048 mutex_enter(&db->db_mtx); 1049 /* 1050 * XXX make this true for indirects too? The problem is that 1051 * transactions created with dmu_tx_create_assigned() from 1052 * syncing context don't bother holding ahead. 1053 */ 1054 ASSERT(db->db_level != 0 || 1055 db->db_state == DB_CACHED || db->db_state == DB_FILL || 1056 db->db_state == DB_NOFILL); 1057 1058 mutex_enter(&dn->dn_mtx); 1059 /* 1060 * Don't set dirtyctx to SYNC if we're just modifying this as we 1061 * initialize the objset. 1062 */ 1063 if (dn->dn_dirtyctx == DN_UNDIRTIED && 1064 !BP_IS_HOLE(dn->dn_objset->os_rootbp)) { 1065 dn->dn_dirtyctx = 1066 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN); 1067 ASSERT(dn->dn_dirtyctx_firstset == NULL); 1068 dn->dn_dirtyctx_firstset = kmem_alloc(1, KM_SLEEP); 1069 } 1070 mutex_exit(&dn->dn_mtx); 1071 1072 if (db->db_blkid == DMU_SPILL_BLKID) 1073 dn->dn_have_spill = B_TRUE; 1074 1075 /* 1076 * If this buffer is already dirty, we're done. 1077 */ 1078 drp = &db->db_last_dirty; 1079 ASSERT(*drp == NULL || (*drp)->dr_txg <= tx->tx_txg || 1080 db->db.db_object == DMU_META_DNODE_OBJECT); 1081 while ((dr = *drp) != NULL && dr->dr_txg > tx->tx_txg) 1082 drp = &dr->dr_next; 1083 if (dr && dr->dr_txg == tx->tx_txg) { 1084 DB_DNODE_EXIT(db); 1085 1086 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID) { 1087 /* 1088 * If this buffer has already been written out, 1089 * we now need to reset its state. 1090 */ 1091 dbuf_unoverride(dr); 1092 if (db->db.db_object != DMU_META_DNODE_OBJECT && 1093 db->db_state != DB_NOFILL) 1094 arc_buf_thaw(db->db_buf); 1095 } 1096 mutex_exit(&db->db_mtx); 1097 return (dr); 1098 } 1099 1100 /* 1101 * Only valid if not already dirty. 1102 */ 1103 ASSERT(dn->dn_object == 0 || 1104 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx == 1105 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN)); 1106 1107 ASSERT3U(dn->dn_nlevels, >, db->db_level); 1108 ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) || 1109 dn->dn_phys->dn_nlevels > db->db_level || 1110 dn->dn_next_nlevels[txgoff] > db->db_level || 1111 dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level || 1112 dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level); 1113 1114 /* 1115 * We should only be dirtying in syncing context if it's the 1116 * mos or we're initializing the os or it's a special object. 1117 * However, we are allowed to dirty in syncing context provided 1118 * we already dirtied it in open context. Hence we must make 1119 * this assertion only if we're not already dirty. 1120 */ 1121 os = dn->dn_objset; 1122 ASSERT(!dmu_tx_is_syncing(tx) || DMU_OBJECT_IS_SPECIAL(dn->dn_object) || 1123 os->os_dsl_dataset == NULL || BP_IS_HOLE(os->os_rootbp)); 1124 ASSERT(db->db.db_size != 0); 1125 1126 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size); 1127 1128 if (db->db_blkid != DMU_BONUS_BLKID) { 1129 /* 1130 * Update the accounting. 1131 * Note: we delay "free accounting" until after we drop 1132 * the db_mtx. This keeps us from grabbing other locks 1133 * (and possibly deadlocking) in bp_get_dsize() while 1134 * also holding the db_mtx. 1135 */ 1136 dnode_willuse_space(dn, db->db.db_size, tx); 1137 do_free_accounting = dbuf_block_freeable(db); 1138 } 1139 1140 /* 1141 * If this buffer is dirty in an old transaction group we need 1142 * to make a copy of it so that the changes we make in this 1143 * transaction group won't leak out when we sync the older txg. 1144 */ 1145 dr = kmem_zalloc(sizeof (dbuf_dirty_record_t), KM_SLEEP); 1146 if (db->db_level == 0) { 1147 void *data_old = db->db_buf; 1148 1149 if (db->db_state != DB_NOFILL) { 1150 if (db->db_blkid == DMU_BONUS_BLKID) { 1151 dbuf_fix_old_data(db, tx->tx_txg); 1152 data_old = db->db.db_data; 1153 } else if (db->db.db_object != DMU_META_DNODE_OBJECT) { 1154 /* 1155 * Release the data buffer from the cache so 1156 * that we can modify it without impacting 1157 * possible other users of this cached data 1158 * block. Note that indirect blocks and 1159 * private objects are not released until the 1160 * syncing state (since they are only modified 1161 * then). 1162 */ 1163 arc_release(db->db_buf, db); 1164 dbuf_fix_old_data(db, tx->tx_txg); 1165 data_old = db->db_buf; 1166 } 1167 ASSERT(data_old != NULL); 1168 } 1169 dr->dt.dl.dr_data = data_old; 1170 } else { 1171 mutex_init(&dr->dt.di.dr_mtx, NULL, MUTEX_DEFAULT, NULL); 1172 list_create(&dr->dt.di.dr_children, 1173 sizeof (dbuf_dirty_record_t), 1174 offsetof(dbuf_dirty_record_t, dr_dirty_node)); 1175 } 1176 dr->dr_dbuf = db; 1177 dr->dr_txg = tx->tx_txg; 1178 dr->dr_next = *drp; 1179 *drp = dr; 1180 1181 /* 1182 * We could have been freed_in_flight between the dbuf_noread 1183 * and dbuf_dirty. We win, as though the dbuf_noread() had 1184 * happened after the free. 1185 */ 1186 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID && 1187 db->db_blkid != DMU_SPILL_BLKID) { 1188 mutex_enter(&dn->dn_mtx); 1189 dnode_clear_range(dn, db->db_blkid, 1, tx); 1190 mutex_exit(&dn->dn_mtx); 1191 db->db_freed_in_flight = FALSE; 1192 } 1193 1194 /* 1195 * This buffer is now part of this txg 1196 */ 1197 dbuf_add_ref(db, (void *)(uintptr_t)tx->tx_txg); 1198 db->db_dirtycnt += 1; 1199 ASSERT3U(db->db_dirtycnt, <=, 3); 1200 1201 mutex_exit(&db->db_mtx); 1202 1203 if (db->db_blkid == DMU_BONUS_BLKID || 1204 db->db_blkid == DMU_SPILL_BLKID) { 1205 mutex_enter(&dn->dn_mtx); 1206 ASSERT(!list_link_active(&dr->dr_dirty_node)); 1207 list_insert_tail(&dn->dn_dirty_records[txgoff], dr); 1208 mutex_exit(&dn->dn_mtx); 1209 dnode_setdirty(dn, tx); 1210 DB_DNODE_EXIT(db); 1211 return (dr); 1212 } else if (do_free_accounting) { 1213 blkptr_t *bp = db->db_blkptr; 1214 int64_t willfree = (bp && !BP_IS_HOLE(bp)) ? 1215 bp_get_dsize(os->os_spa, bp) : db->db.db_size; 1216 /* 1217 * This is only a guess -- if the dbuf is dirty 1218 * in a previous txg, we don't know how much 1219 * space it will use on disk yet. We should 1220 * really have the struct_rwlock to access 1221 * db_blkptr, but since this is just a guess, 1222 * it's OK if we get an odd answer. 1223 */ 1224 ddt_prefetch(os->os_spa, bp); 1225 dnode_willuse_space(dn, -willfree, tx); 1226 } 1227 1228 if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) { 1229 rw_enter(&dn->dn_struct_rwlock, RW_READER); 1230 drop_struct_lock = TRUE; 1231 } 1232 1233 if (db->db_level == 0) { 1234 dnode_new_blkid(dn, db->db_blkid, tx, drop_struct_lock); 1235 ASSERT(dn->dn_maxblkid >= db->db_blkid); 1236 } 1237 1238 if (db->db_level+1 < dn->dn_nlevels) { 1239 dmu_buf_impl_t *parent = db->db_parent; 1240 dbuf_dirty_record_t *di; 1241 int parent_held = FALSE; 1242 1243 if (db->db_parent == NULL || db->db_parent == dn->dn_dbuf) { 1244 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT; 1245 1246 parent = dbuf_hold_level(dn, db->db_level+1, 1247 db->db_blkid >> epbs, FTAG); 1248 ASSERT(parent != NULL); 1249 parent_held = TRUE; 1250 } 1251 if (drop_struct_lock) 1252 rw_exit(&dn->dn_struct_rwlock); 1253 ASSERT3U(db->db_level+1, ==, parent->db_level); 1254 di = dbuf_dirty(parent, tx); 1255 if (parent_held) 1256 dbuf_rele(parent, FTAG); 1257 1258 mutex_enter(&db->db_mtx); 1259 /* possible race with dbuf_undirty() */ 1260 if (db->db_last_dirty == dr || 1261 dn->dn_object == DMU_META_DNODE_OBJECT) { 1262 mutex_enter(&di->dt.di.dr_mtx); 1263 ASSERT3U(di->dr_txg, ==, tx->tx_txg); 1264 ASSERT(!list_link_active(&dr->dr_dirty_node)); 1265 list_insert_tail(&di->dt.di.dr_children, dr); 1266 mutex_exit(&di->dt.di.dr_mtx); 1267 dr->dr_parent = di; 1268 } 1269 mutex_exit(&db->db_mtx); 1270 } else { 1271 ASSERT(db->db_level+1 == dn->dn_nlevels); 1272 ASSERT(db->db_blkid < dn->dn_nblkptr); 1273 ASSERT(db->db_parent == NULL || db->db_parent == dn->dn_dbuf); 1274 mutex_enter(&dn->dn_mtx); 1275 ASSERT(!list_link_active(&dr->dr_dirty_node)); 1276 list_insert_tail(&dn->dn_dirty_records[txgoff], dr); 1277 mutex_exit(&dn->dn_mtx); 1278 if (drop_struct_lock) 1279 rw_exit(&dn->dn_struct_rwlock); 1280 } 1281 1282 dnode_setdirty(dn, tx); 1283 DB_DNODE_EXIT(db); 1284 return (dr); 1285 } 1286 1287 static int 1288 dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx) 1289 { 1290 dnode_t *dn; 1291 uint64_t txg = tx->tx_txg; 1292 dbuf_dirty_record_t *dr, **drp; 1293 1294 ASSERT(txg != 0); 1295 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1296 1297 mutex_enter(&db->db_mtx); 1298 /* 1299 * If this buffer is not dirty, we're done. 1300 */ 1301 for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next) 1302 if (dr->dr_txg <= txg) 1303 break; 1304 if (dr == NULL || dr->dr_txg < txg) { 1305 mutex_exit(&db->db_mtx); 1306 return (0); 1307 } 1308 ASSERT(dr->dr_txg == txg); 1309 ASSERT(dr->dr_dbuf == db); 1310 1311 DB_DNODE_ENTER(db); 1312 dn = DB_DNODE(db); 1313 1314 /* 1315 * If this buffer is currently held, we cannot undirty 1316 * it, since one of the current holders may be in the 1317 * middle of an update. Note that users of dbuf_undirty() 1318 * should not place a hold on the dbuf before the call. 1319 * Also note: we can get here with a spill block, so 1320 * test for that similar to how dbuf_dirty does. 1321 */ 1322 if (refcount_count(&db->db_holds) > db->db_dirtycnt) { 1323 mutex_exit(&db->db_mtx); 1324 /* Make sure we don't toss this buffer at sync phase */ 1325 if (db->db_blkid != DMU_SPILL_BLKID) { 1326 mutex_enter(&dn->dn_mtx); 1327 dnode_clear_range(dn, db->db_blkid, 1, tx); 1328 mutex_exit(&dn->dn_mtx); 1329 } 1330 DB_DNODE_EXIT(db); 1331 return (0); 1332 } 1333 1334 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size); 1335 1336 ASSERT(db->db.db_size != 0); 1337 1338 /* XXX would be nice to fix up dn_towrite_space[] */ 1339 1340 *drp = dr->dr_next; 1341 1342 /* 1343 * Note that there are three places in dbuf_dirty() 1344 * where this dirty record may be put on a list. 1345 * Make sure to do a list_remove corresponding to 1346 * every one of those list_insert calls. 1347 */ 1348 if (dr->dr_parent) { 1349 mutex_enter(&dr->dr_parent->dt.di.dr_mtx); 1350 list_remove(&dr->dr_parent->dt.di.dr_children, dr); 1351 mutex_exit(&dr->dr_parent->dt.di.dr_mtx); 1352 } else if (db->db_blkid == DMU_SPILL_BLKID || 1353 db->db_level+1 == dn->dn_nlevels) { 1354 ASSERT(db->db_blkptr == NULL || db->db_parent == dn->dn_dbuf); 1355 mutex_enter(&dn->dn_mtx); 1356 list_remove(&dn->dn_dirty_records[txg & TXG_MASK], dr); 1357 mutex_exit(&dn->dn_mtx); 1358 } 1359 DB_DNODE_EXIT(db); 1360 1361 if (db->db_level == 0) { 1362 if (db->db_state != DB_NOFILL) { 1363 dbuf_unoverride(dr); 1364 1365 ASSERT(db->db_buf != NULL); 1366 ASSERT(dr->dt.dl.dr_data != NULL); 1367 if (dr->dt.dl.dr_data != db->db_buf) 1368 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data, 1369 db) == 1); 1370 } 1371 } else { 1372 ASSERT(db->db_buf != NULL); 1373 ASSERT(list_head(&dr->dt.di.dr_children) == NULL); 1374 mutex_destroy(&dr->dt.di.dr_mtx); 1375 list_destroy(&dr->dt.di.dr_children); 1376 } 1377 kmem_free(dr, sizeof (dbuf_dirty_record_t)); 1378 1379 ASSERT(db->db_dirtycnt > 0); 1380 db->db_dirtycnt -= 1; 1381 1382 if (refcount_remove(&db->db_holds, (void *)(uintptr_t)txg) == 0) { 1383 arc_buf_t *buf = db->db_buf; 1384 1385 ASSERT(db->db_state == DB_NOFILL || arc_released(buf)); 1386 dbuf_set_data(db, NULL); 1387 VERIFY(arc_buf_remove_ref(buf, db) == 1); 1388 dbuf_evict(db); 1389 return (1); 1390 } 1391 1392 mutex_exit(&db->db_mtx); 1393 return (0); 1394 } 1395 1396 #pragma weak dmu_buf_will_dirty = dbuf_will_dirty 1397 void 1398 dbuf_will_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx) 1399 { 1400 int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH; 1401 1402 ASSERT(tx->tx_txg != 0); 1403 ASSERT(!refcount_is_zero(&db->db_holds)); 1404 1405 DB_DNODE_ENTER(db); 1406 if (RW_WRITE_HELD(&DB_DNODE(db)->dn_struct_rwlock)) 1407 rf |= DB_RF_HAVESTRUCT; 1408 DB_DNODE_EXIT(db); 1409 (void) dbuf_read(db, NULL, rf); 1410 (void) dbuf_dirty(db, tx); 1411 } 1412 1413 void 1414 dmu_buf_will_not_fill(dmu_buf_t *db_fake, dmu_tx_t *tx) 1415 { 1416 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 1417 1418 db->db_state = DB_NOFILL; 1419 1420 dmu_buf_will_fill(db_fake, tx); 1421 } 1422 1423 void 1424 dmu_buf_will_fill(dmu_buf_t *db_fake, dmu_tx_t *tx) 1425 { 1426 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 1427 1428 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1429 ASSERT(tx->tx_txg != 0); 1430 ASSERT(db->db_level == 0); 1431 ASSERT(!refcount_is_zero(&db->db_holds)); 1432 1433 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT || 1434 dmu_tx_private_ok(tx)); 1435 1436 dbuf_noread(db); 1437 (void) dbuf_dirty(db, tx); 1438 } 1439 1440 #pragma weak dmu_buf_fill_done = dbuf_fill_done 1441 /* ARGSUSED */ 1442 void 1443 dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx) 1444 { 1445 mutex_enter(&db->db_mtx); 1446 DBUF_VERIFY(db); 1447 1448 if (db->db_state == DB_FILL) { 1449 if (db->db_level == 0 && db->db_freed_in_flight) { 1450 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1451 /* we were freed while filling */ 1452 /* XXX dbuf_undirty? */ 1453 bzero(db->db.db_data, db->db.db_size); 1454 db->db_freed_in_flight = FALSE; 1455 } 1456 db->db_state = DB_CACHED; 1457 cv_broadcast(&db->db_changed); 1458 } 1459 mutex_exit(&db->db_mtx); 1460 } 1461 1462 /* 1463 * Directly assign a provided arc buf to a given dbuf if it's not referenced 1464 * by anybody except our caller. Otherwise copy arcbuf's contents to dbuf. 1465 */ 1466 void 1467 dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx) 1468 { 1469 ASSERT(!refcount_is_zero(&db->db_holds)); 1470 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1471 ASSERT(db->db_level == 0); 1472 ASSERT(DBUF_GET_BUFC_TYPE(db) == ARC_BUFC_DATA); 1473 ASSERT(buf != NULL); 1474 ASSERT(arc_buf_size(buf) == db->db.db_size); 1475 ASSERT(tx->tx_txg != 0); 1476 1477 arc_return_buf(buf, db); 1478 ASSERT(arc_released(buf)); 1479 1480 mutex_enter(&db->db_mtx); 1481 1482 while (db->db_state == DB_READ || db->db_state == DB_FILL) 1483 cv_wait(&db->db_changed, &db->db_mtx); 1484 1485 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED); 1486 1487 if (db->db_state == DB_CACHED && 1488 refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) { 1489 mutex_exit(&db->db_mtx); 1490 (void) dbuf_dirty(db, tx); 1491 bcopy(buf->b_data, db->db.db_data, db->db.db_size); 1492 VERIFY(arc_buf_remove_ref(buf, db) == 1); 1493 xuio_stat_wbuf_copied(); 1494 return; 1495 } 1496 1497 xuio_stat_wbuf_nocopy(); 1498 if (db->db_state == DB_CACHED) { 1499 dbuf_dirty_record_t *dr = db->db_last_dirty; 1500 1501 ASSERT(db->db_buf != NULL); 1502 if (dr != NULL && dr->dr_txg == tx->tx_txg) { 1503 ASSERT(dr->dt.dl.dr_data == db->db_buf); 1504 if (!arc_released(db->db_buf)) { 1505 ASSERT(dr->dt.dl.dr_override_state == 1506 DR_OVERRIDDEN); 1507 arc_release(db->db_buf, db); 1508 } 1509 dr->dt.dl.dr_data = buf; 1510 VERIFY(arc_buf_remove_ref(db->db_buf, db) == 1); 1511 } else if (dr == NULL || dr->dt.dl.dr_data != db->db_buf) { 1512 arc_release(db->db_buf, db); 1513 VERIFY(arc_buf_remove_ref(db->db_buf, db) == 1); 1514 } 1515 db->db_buf = NULL; 1516 } 1517 ASSERT(db->db_buf == NULL); 1518 dbuf_set_data(db, buf); 1519 db->db_state = DB_FILL; 1520 mutex_exit(&db->db_mtx); 1521 (void) dbuf_dirty(db, tx); 1522 dbuf_fill_done(db, tx); 1523 } 1524 1525 /* 1526 * "Clear" the contents of this dbuf. This will mark the dbuf 1527 * EVICTING and clear *most* of its references. Unfortunetely, 1528 * when we are not holding the dn_dbufs_mtx, we can't clear the 1529 * entry in the dn_dbufs list. We have to wait until dbuf_destroy() 1530 * in this case. For callers from the DMU we will usually see: 1531 * dbuf_clear()->arc_buf_evict()->dbuf_do_evict()->dbuf_destroy() 1532 * For the arc callback, we will usually see: 1533 * dbuf_do_evict()->dbuf_clear();dbuf_destroy() 1534 * Sometimes, though, we will get a mix of these two: 1535 * DMU: dbuf_clear()->arc_buf_evict() 1536 * ARC: dbuf_do_evict()->dbuf_destroy() 1537 */ 1538 void 1539 dbuf_clear(dmu_buf_impl_t *db) 1540 { 1541 dnode_t *dn; 1542 dmu_buf_impl_t *parent = db->db_parent; 1543 dmu_buf_impl_t *dndb; 1544 int dbuf_gone = FALSE; 1545 1546 ASSERT(MUTEX_HELD(&db->db_mtx)); 1547 ASSERT(refcount_is_zero(&db->db_holds)); 1548 1549 dbuf_evict_user(db); 1550 1551 if (db->db_state == DB_CACHED) { 1552 ASSERT(db->db.db_data != NULL); 1553 if (db->db_blkid == DMU_BONUS_BLKID) { 1554 zio_buf_free(db->db.db_data, DN_MAX_BONUSLEN); 1555 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER); 1556 } 1557 db->db.db_data = NULL; 1558 db->db_state = DB_UNCACHED; 1559 } 1560 1561 ASSERT(db->db_state == DB_UNCACHED || db->db_state == DB_NOFILL); 1562 ASSERT(db->db_data_pending == NULL); 1563 1564 db->db_state = DB_EVICTING; 1565 db->db_blkptr = NULL; 1566 1567 DB_DNODE_ENTER(db); 1568 dn = DB_DNODE(db); 1569 dndb = dn->dn_dbuf; 1570 if (db->db_blkid != DMU_BONUS_BLKID && MUTEX_HELD(&dn->dn_dbufs_mtx)) { 1571 list_remove(&dn->dn_dbufs, db); 1572 (void) atomic_dec_32_nv(&dn->dn_dbufs_count); 1573 membar_producer(); 1574 DB_DNODE_EXIT(db); 1575 /* 1576 * Decrementing the dbuf count means that the hold corresponding 1577 * to the removed dbuf is no longer discounted in dnode_move(), 1578 * so the dnode cannot be moved until after we release the hold. 1579 * The membar_producer() ensures visibility of the decremented 1580 * value in dnode_move(), since DB_DNODE_EXIT doesn't actually 1581 * release any lock. 1582 */ 1583 dnode_rele(dn, db); 1584 db->db_dnode_handle = NULL; 1585 } else { 1586 DB_DNODE_EXIT(db); 1587 } 1588 1589 if (db->db_buf) 1590 dbuf_gone = arc_buf_evict(db->db_buf); 1591 1592 if (!dbuf_gone) 1593 mutex_exit(&db->db_mtx); 1594 1595 /* 1596 * If this dbuf is referenced from an indirect dbuf, 1597 * decrement the ref count on the indirect dbuf. 1598 */ 1599 if (parent && parent != dndb) 1600 dbuf_rele(parent, db); 1601 } 1602 1603 static int 1604 dbuf_findbp(dnode_t *dn, int level, uint64_t blkid, int fail_sparse, 1605 dmu_buf_impl_t **parentp, blkptr_t **bpp) 1606 { 1607 int nlevels, epbs; 1608 1609 *parentp = NULL; 1610 *bpp = NULL; 1611 1612 ASSERT(blkid != DMU_BONUS_BLKID); 1613 1614 if (blkid == DMU_SPILL_BLKID) { 1615 mutex_enter(&dn->dn_mtx); 1616 if (dn->dn_have_spill && 1617 (dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR)) 1618 *bpp = &dn->dn_phys->dn_spill; 1619 else 1620 *bpp = NULL; 1621 dbuf_add_ref(dn->dn_dbuf, NULL); 1622 *parentp = dn->dn_dbuf; 1623 mutex_exit(&dn->dn_mtx); 1624 return (0); 1625 } 1626 1627 if (dn->dn_phys->dn_nlevels == 0) 1628 nlevels = 1; 1629 else 1630 nlevels = dn->dn_phys->dn_nlevels; 1631 1632 epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT; 1633 1634 ASSERT3U(level * epbs, <, 64); 1635 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 1636 if (level >= nlevels || 1637 (blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))) { 1638 /* the buffer has no parent yet */ 1639 return (ENOENT); 1640 } else if (level < nlevels-1) { 1641 /* this block is referenced from an indirect block */ 1642 int err = dbuf_hold_impl(dn, level+1, 1643 blkid >> epbs, fail_sparse, NULL, parentp); 1644 if (err) 1645 return (err); 1646 err = dbuf_read(*parentp, NULL, 1647 (DB_RF_HAVESTRUCT | DB_RF_NOPREFETCH | DB_RF_CANFAIL)); 1648 if (err) { 1649 dbuf_rele(*parentp, NULL); 1650 *parentp = NULL; 1651 return (err); 1652 } 1653 *bpp = ((blkptr_t *)(*parentp)->db.db_data) + 1654 (blkid & ((1ULL << epbs) - 1)); 1655 return (0); 1656 } else { 1657 /* the block is referenced from the dnode */ 1658 ASSERT3U(level, ==, nlevels-1); 1659 ASSERT(dn->dn_phys->dn_nblkptr == 0 || 1660 blkid < dn->dn_phys->dn_nblkptr); 1661 if (dn->dn_dbuf) { 1662 dbuf_add_ref(dn->dn_dbuf, NULL); 1663 *parentp = dn->dn_dbuf; 1664 } 1665 *bpp = &dn->dn_phys->dn_blkptr[blkid]; 1666 return (0); 1667 } 1668 } 1669 1670 static dmu_buf_impl_t * 1671 dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid, 1672 dmu_buf_impl_t *parent, blkptr_t *blkptr) 1673 { 1674 objset_t *os = dn->dn_objset; 1675 dmu_buf_impl_t *db, *odb; 1676 1677 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 1678 ASSERT(dn->dn_type != DMU_OT_NONE); 1679 1680 db = kmem_cache_alloc(dbuf_cache, KM_SLEEP); 1681 1682 db->db_objset = os; 1683 db->db.db_object = dn->dn_object; 1684 db->db_level = level; 1685 db->db_blkid = blkid; 1686 db->db_last_dirty = NULL; 1687 db->db_dirtycnt = 0; 1688 db->db_dnode_handle = dn->dn_handle; 1689 db->db_parent = parent; 1690 db->db_blkptr = blkptr; 1691 1692 db->db_user_ptr = NULL; 1693 db->db_user_data_ptr_ptr = NULL; 1694 db->db_evict_func = NULL; 1695 db->db_immediate_evict = 0; 1696 db->db_freed_in_flight = 0; 1697 1698 if (blkid == DMU_BONUS_BLKID) { 1699 ASSERT3P(parent, ==, dn->dn_dbuf); 1700 db->db.db_size = DN_MAX_BONUSLEN - 1701 (dn->dn_nblkptr-1) * sizeof (blkptr_t); 1702 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen); 1703 db->db.db_offset = DMU_BONUS_BLKID; 1704 db->db_state = DB_UNCACHED; 1705 /* the bonus dbuf is not placed in the hash table */ 1706 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER); 1707 return (db); 1708 } else if (blkid == DMU_SPILL_BLKID) { 1709 db->db.db_size = (blkptr != NULL) ? 1710 BP_GET_LSIZE(blkptr) : SPA_MINBLOCKSIZE; 1711 db->db.db_offset = 0; 1712 } else { 1713 int blocksize = 1714 db->db_level ? 1<<dn->dn_indblkshift : dn->dn_datablksz; 1715 db->db.db_size = blocksize; 1716 db->db.db_offset = db->db_blkid * blocksize; 1717 } 1718 1719 /* 1720 * Hold the dn_dbufs_mtx while we get the new dbuf 1721 * in the hash table *and* added to the dbufs list. 1722 * This prevents a possible deadlock with someone 1723 * trying to look up this dbuf before its added to the 1724 * dn_dbufs list. 1725 */ 1726 mutex_enter(&dn->dn_dbufs_mtx); 1727 db->db_state = DB_EVICTING; 1728 if ((odb = dbuf_hash_insert(db)) != NULL) { 1729 /* someone else inserted it first */ 1730 kmem_cache_free(dbuf_cache, db); 1731 mutex_exit(&dn->dn_dbufs_mtx); 1732 return (odb); 1733 } 1734 list_insert_head(&dn->dn_dbufs, db); 1735 db->db_state = DB_UNCACHED; 1736 mutex_exit(&dn->dn_dbufs_mtx); 1737 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER); 1738 1739 if (parent && parent != dn->dn_dbuf) 1740 dbuf_add_ref(parent, db); 1741 1742 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT || 1743 refcount_count(&dn->dn_holds) > 0); 1744 (void) refcount_add(&dn->dn_holds, db); 1745 (void) atomic_inc_32_nv(&dn->dn_dbufs_count); 1746 1747 dprintf_dbuf(db, "db=%p\n", db); 1748 1749 return (db); 1750 } 1751 1752 static int 1753 dbuf_do_evict(void *private) 1754 { 1755 arc_buf_t *buf = private; 1756 dmu_buf_impl_t *db = buf->b_private; 1757 1758 if (!MUTEX_HELD(&db->db_mtx)) 1759 mutex_enter(&db->db_mtx); 1760 1761 ASSERT(refcount_is_zero(&db->db_holds)); 1762 1763 if (db->db_state != DB_EVICTING) { 1764 ASSERT(db->db_state == DB_CACHED); 1765 DBUF_VERIFY(db); 1766 db->db_buf = NULL; 1767 dbuf_evict(db); 1768 } else { 1769 mutex_exit(&db->db_mtx); 1770 dbuf_destroy(db); 1771 } 1772 return (0); 1773 } 1774 1775 static void 1776 dbuf_destroy(dmu_buf_impl_t *db) 1777 { 1778 ASSERT(refcount_is_zero(&db->db_holds)); 1779 1780 if (db->db_blkid != DMU_BONUS_BLKID) { 1781 /* 1782 * If this dbuf is still on the dn_dbufs list, 1783 * remove it from that list. 1784 */ 1785 if (db->db_dnode_handle != NULL) { 1786 dnode_t *dn; 1787 1788 DB_DNODE_ENTER(db); 1789 dn = DB_DNODE(db); 1790 mutex_enter(&dn->dn_dbufs_mtx); 1791 list_remove(&dn->dn_dbufs, db); 1792 (void) atomic_dec_32_nv(&dn->dn_dbufs_count); 1793 mutex_exit(&dn->dn_dbufs_mtx); 1794 DB_DNODE_EXIT(db); 1795 /* 1796 * Decrementing the dbuf count means that the hold 1797 * corresponding to the removed dbuf is no longer 1798 * discounted in dnode_move(), so the dnode cannot be 1799 * moved until after we release the hold. 1800 */ 1801 dnode_rele(dn, db); 1802 db->db_dnode_handle = NULL; 1803 } 1804 dbuf_hash_remove(db); 1805 } 1806 db->db_parent = NULL; 1807 db->db_buf = NULL; 1808 1809 ASSERT(!list_link_active(&db->db_link)); 1810 ASSERT(db->db.db_data == NULL); 1811 ASSERT(db->db_hash_next == NULL); 1812 ASSERT(db->db_blkptr == NULL); 1813 ASSERT(db->db_data_pending == NULL); 1814 1815 kmem_cache_free(dbuf_cache, db); 1816 arc_space_return(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER); 1817 } 1818 1819 void 1820 dbuf_prefetch(dnode_t *dn, uint64_t blkid) 1821 { 1822 dmu_buf_impl_t *db = NULL; 1823 blkptr_t *bp = NULL; 1824 1825 ASSERT(blkid != DMU_BONUS_BLKID); 1826 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 1827 1828 if (dnode_block_freed(dn, blkid)) 1829 return; 1830 1831 /* dbuf_find() returns with db_mtx held */ 1832 if (db = dbuf_find(dn, 0, blkid)) { 1833 /* 1834 * This dbuf is already in the cache. We assume that 1835 * it is already CACHED, or else about to be either 1836 * read or filled. 1837 */ 1838 mutex_exit(&db->db_mtx); 1839 return; 1840 } 1841 1842 if (dbuf_findbp(dn, 0, blkid, TRUE, &db, &bp) == 0) { 1843 if (bp && !BP_IS_HOLE(bp)) { 1844 int priority = dn->dn_type == DMU_OT_DDT_ZAP ? 1845 ZIO_PRIORITY_DDT_PREFETCH : ZIO_PRIORITY_ASYNC_READ; 1846 arc_buf_t *pbuf; 1847 dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset; 1848 uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH; 1849 zbookmark_t zb; 1850 1851 SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET, 1852 dn->dn_object, 0, blkid); 1853 1854 if (db) 1855 pbuf = db->db_buf; 1856 else 1857 pbuf = dn->dn_objset->os_phys_buf; 1858 1859 (void) dsl_read(NULL, dn->dn_objset->os_spa, 1860 bp, pbuf, NULL, NULL, priority, 1861 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE, 1862 &aflags, &zb); 1863 } 1864 if (db) 1865 dbuf_rele(db, NULL); 1866 } 1867 } 1868 1869 /* 1870 * Returns with db_holds incremented, and db_mtx not held. 1871 * Note: dn_struct_rwlock must be held. 1872 */ 1873 int 1874 dbuf_hold_impl(dnode_t *dn, uint8_t level, uint64_t blkid, int fail_sparse, 1875 void *tag, dmu_buf_impl_t **dbp) 1876 { 1877 dmu_buf_impl_t *db, *parent = NULL; 1878 1879 ASSERT(blkid != DMU_BONUS_BLKID); 1880 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 1881 ASSERT3U(dn->dn_nlevels, >, level); 1882 1883 *dbp = NULL; 1884 top: 1885 /* dbuf_find() returns with db_mtx held */ 1886 db = dbuf_find(dn, level, blkid); 1887 1888 if (db == NULL) { 1889 blkptr_t *bp = NULL; 1890 int err; 1891 1892 ASSERT3P(parent, ==, NULL); 1893 err = dbuf_findbp(dn, level, blkid, fail_sparse, &parent, &bp); 1894 if (fail_sparse) { 1895 if (err == 0 && bp && BP_IS_HOLE(bp)) 1896 err = ENOENT; 1897 if (err) { 1898 if (parent) 1899 dbuf_rele(parent, NULL); 1900 return (err); 1901 } 1902 } 1903 if (err && err != ENOENT) 1904 return (err); 1905 db = dbuf_create(dn, level, blkid, parent, bp); 1906 } 1907 1908 if (db->db_buf && refcount_is_zero(&db->db_holds)) { 1909 arc_buf_add_ref(db->db_buf, db); 1910 if (db->db_buf->b_data == NULL) { 1911 dbuf_clear(db); 1912 if (parent) { 1913 dbuf_rele(parent, NULL); 1914 parent = NULL; 1915 } 1916 goto top; 1917 } 1918 ASSERT3P(db->db.db_data, ==, db->db_buf->b_data); 1919 } 1920 1921 ASSERT(db->db_buf == NULL || arc_referenced(db->db_buf)); 1922 1923 /* 1924 * If this buffer is currently syncing out, and we are are 1925 * still referencing it from db_data, we need to make a copy 1926 * of it in case we decide we want to dirty it again in this txg. 1927 */ 1928 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID && 1929 dn->dn_object != DMU_META_DNODE_OBJECT && 1930 db->db_state == DB_CACHED && db->db_data_pending) { 1931 dbuf_dirty_record_t *dr = db->db_data_pending; 1932 1933 if (dr->dt.dl.dr_data == db->db_buf) { 1934 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 1935 1936 dbuf_set_data(db, 1937 arc_buf_alloc(dn->dn_objset->os_spa, 1938 db->db.db_size, db, type)); 1939 bcopy(dr->dt.dl.dr_data->b_data, db->db.db_data, 1940 db->db.db_size); 1941 } 1942 } 1943 1944 (void) refcount_add(&db->db_holds, tag); 1945 dbuf_update_data(db); 1946 DBUF_VERIFY(db); 1947 mutex_exit(&db->db_mtx); 1948 1949 /* NOTE: we can't rele the parent until after we drop the db_mtx */ 1950 if (parent) 1951 dbuf_rele(parent, NULL); 1952 1953 ASSERT3P(DB_DNODE(db), ==, dn); 1954 ASSERT3U(db->db_blkid, ==, blkid); 1955 ASSERT3U(db->db_level, ==, level); 1956 *dbp = db; 1957 1958 return (0); 1959 } 1960 1961 dmu_buf_impl_t * 1962 dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag) 1963 { 1964 dmu_buf_impl_t *db; 1965 int err = dbuf_hold_impl(dn, 0, blkid, FALSE, tag, &db); 1966 return (err ? NULL : db); 1967 } 1968 1969 dmu_buf_impl_t * 1970 dbuf_hold_level(dnode_t *dn, int level, uint64_t blkid, void *tag) 1971 { 1972 dmu_buf_impl_t *db; 1973 int err = dbuf_hold_impl(dn, level, blkid, FALSE, tag, &db); 1974 return (err ? NULL : db); 1975 } 1976 1977 void 1978 dbuf_create_bonus(dnode_t *dn) 1979 { 1980 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock)); 1981 1982 ASSERT(dn->dn_bonus == NULL); 1983 dn->dn_bonus = dbuf_create(dn, 0, DMU_BONUS_BLKID, dn->dn_dbuf, NULL); 1984 } 1985 1986 int 1987 dbuf_spill_set_blksz(dmu_buf_t *db_fake, uint64_t blksz, dmu_tx_t *tx) 1988 { 1989 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 1990 dnode_t *dn; 1991 1992 if (db->db_blkid != DMU_SPILL_BLKID) 1993 return (ENOTSUP); 1994 if (blksz == 0) 1995 blksz = SPA_MINBLOCKSIZE; 1996 if (blksz > SPA_MAXBLOCKSIZE) 1997 blksz = SPA_MAXBLOCKSIZE; 1998 else 1999 blksz = P2ROUNDUP(blksz, SPA_MINBLOCKSIZE); 2000 2001 DB_DNODE_ENTER(db); 2002 dn = DB_DNODE(db); 2003 rw_enter(&dn->dn_struct_rwlock, RW_WRITER); 2004 dbuf_new_size(db, blksz, tx); 2005 rw_exit(&dn->dn_struct_rwlock); 2006 DB_DNODE_EXIT(db); 2007 2008 return (0); 2009 } 2010 2011 void 2012 dbuf_rm_spill(dnode_t *dn, dmu_tx_t *tx) 2013 { 2014 dbuf_free_range(dn, DMU_SPILL_BLKID, DMU_SPILL_BLKID, tx); 2015 } 2016 2017 #pragma weak dmu_buf_add_ref = dbuf_add_ref 2018 void 2019 dbuf_add_ref(dmu_buf_impl_t *db, void *tag) 2020 { 2021 int64_t holds = refcount_add(&db->db_holds, tag); 2022 ASSERT(holds > 1); 2023 } 2024 2025 /* 2026 * If you call dbuf_rele() you had better not be referencing the dnode handle 2027 * unless you have some other direct or indirect hold on the dnode. (An indirect 2028 * hold is a hold on one of the dnode's dbufs, including the bonus buffer.) 2029 * Without that, the dbuf_rele() could lead to a dnode_rele() followed by the 2030 * dnode's parent dbuf evicting its dnode handles. 2031 */ 2032 #pragma weak dmu_buf_rele = dbuf_rele 2033 void 2034 dbuf_rele(dmu_buf_impl_t *db, void *tag) 2035 { 2036 mutex_enter(&db->db_mtx); 2037 dbuf_rele_and_unlock(db, tag); 2038 } 2039 2040 /* 2041 * dbuf_rele() for an already-locked dbuf. This is necessary to allow 2042 * db_dirtycnt and db_holds to be updated atomically. 2043 */ 2044 void 2045 dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag) 2046 { 2047 int64_t holds; 2048 2049 ASSERT(MUTEX_HELD(&db->db_mtx)); 2050 DBUF_VERIFY(db); 2051 2052 /* 2053 * Remove the reference to the dbuf before removing its hold on the 2054 * dnode so we can guarantee in dnode_move() that a referenced bonus 2055 * buffer has a corresponding dnode hold. 2056 */ 2057 holds = refcount_remove(&db->db_holds, tag); 2058 ASSERT(holds >= 0); 2059 2060 /* 2061 * We can't freeze indirects if there is a possibility that they 2062 * may be modified in the current syncing context. 2063 */ 2064 if (db->db_buf && holds == (db->db_level == 0 ? db->db_dirtycnt : 0)) 2065 arc_buf_freeze(db->db_buf); 2066 2067 if (holds == db->db_dirtycnt && 2068 db->db_level == 0 && db->db_immediate_evict) 2069 dbuf_evict_user(db); 2070 2071 if (holds == 0) { 2072 if (db->db_blkid == DMU_BONUS_BLKID) { 2073 mutex_exit(&db->db_mtx); 2074 2075 /* 2076 * If the dnode moves here, we cannot cross this barrier 2077 * until the move completes. 2078 */ 2079 DB_DNODE_ENTER(db); 2080 (void) atomic_dec_32_nv(&DB_DNODE(db)->dn_dbufs_count); 2081 DB_DNODE_EXIT(db); 2082 /* 2083 * The bonus buffer's dnode hold is no longer discounted 2084 * in dnode_move(). The dnode cannot move until after 2085 * the dnode_rele(). 2086 */ 2087 dnode_rele(DB_DNODE(db), db); 2088 } else if (db->db_buf == NULL) { 2089 /* 2090 * This is a special case: we never associated this 2091 * dbuf with any data allocated from the ARC. 2092 */ 2093 ASSERT(db->db_state == DB_UNCACHED || 2094 db->db_state == DB_NOFILL); 2095 dbuf_evict(db); 2096 } else if (arc_released(db->db_buf)) { 2097 arc_buf_t *buf = db->db_buf; 2098 /* 2099 * This dbuf has anonymous data associated with it. 2100 */ 2101 dbuf_set_data(db, NULL); 2102 VERIFY(arc_buf_remove_ref(buf, db) == 1); 2103 dbuf_evict(db); 2104 } else { 2105 VERIFY(arc_buf_remove_ref(db->db_buf, db) == 0); 2106 2107 /* 2108 * A dbuf will be eligible for eviction if either the 2109 * 'primarycache' property is set or a duplicate 2110 * copy of this buffer is already cached in the arc. 2111 * 2112 * In the case of the 'primarycache' a buffer 2113 * is considered for eviction if it matches the 2114 * criteria set in the property. 2115 * 2116 * To decide if our buffer is considered a 2117 * duplicate, we must call into the arc to determine 2118 * if multiple buffers are referencing the same 2119 * block on-disk. If so, then we simply evict 2120 * ourselves. 2121 */ 2122 if (!DBUF_IS_CACHEABLE(db) || 2123 arc_buf_eviction_needed(db->db_buf)) 2124 dbuf_clear(db); 2125 else 2126 mutex_exit(&db->db_mtx); 2127 } 2128 } else { 2129 mutex_exit(&db->db_mtx); 2130 } 2131 } 2132 2133 #pragma weak dmu_buf_refcount = dbuf_refcount 2134 uint64_t 2135 dbuf_refcount(dmu_buf_impl_t *db) 2136 { 2137 return (refcount_count(&db->db_holds)); 2138 } 2139 2140 void * 2141 dmu_buf_set_user(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr, 2142 dmu_buf_evict_func_t *evict_func) 2143 { 2144 return (dmu_buf_update_user(db_fake, NULL, user_ptr, 2145 user_data_ptr_ptr, evict_func)); 2146 } 2147 2148 void * 2149 dmu_buf_set_user_ie(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr, 2150 dmu_buf_evict_func_t *evict_func) 2151 { 2152 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 2153 2154 db->db_immediate_evict = TRUE; 2155 return (dmu_buf_update_user(db_fake, NULL, user_ptr, 2156 user_data_ptr_ptr, evict_func)); 2157 } 2158 2159 void * 2160 dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr, void *user_ptr, 2161 void *user_data_ptr_ptr, dmu_buf_evict_func_t *evict_func) 2162 { 2163 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 2164 ASSERT(db->db_level == 0); 2165 2166 ASSERT((user_ptr == NULL) == (evict_func == NULL)); 2167 2168 mutex_enter(&db->db_mtx); 2169 2170 if (db->db_user_ptr == old_user_ptr) { 2171 db->db_user_ptr = user_ptr; 2172 db->db_user_data_ptr_ptr = user_data_ptr_ptr; 2173 db->db_evict_func = evict_func; 2174 2175 dbuf_update_data(db); 2176 } else { 2177 old_user_ptr = db->db_user_ptr; 2178 } 2179 2180 mutex_exit(&db->db_mtx); 2181 return (old_user_ptr); 2182 } 2183 2184 void * 2185 dmu_buf_get_user(dmu_buf_t *db_fake) 2186 { 2187 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 2188 ASSERT(!refcount_is_zero(&db->db_holds)); 2189 2190 return (db->db_user_ptr); 2191 } 2192 2193 boolean_t 2194 dmu_buf_freeable(dmu_buf_t *dbuf) 2195 { 2196 boolean_t res = B_FALSE; 2197 dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf; 2198 2199 if (db->db_blkptr) 2200 res = dsl_dataset_block_freeable(db->db_objset->os_dsl_dataset, 2201 db->db_blkptr, db->db_blkptr->blk_birth); 2202 2203 return (res); 2204 } 2205 2206 blkptr_t * 2207 dmu_buf_get_blkptr(dmu_buf_t *db) 2208 { 2209 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db; 2210 return (dbi->db_blkptr); 2211 } 2212 2213 static void 2214 dbuf_check_blkptr(dnode_t *dn, dmu_buf_impl_t *db) 2215 { 2216 /* ASSERT(dmu_tx_is_syncing(tx) */ 2217 ASSERT(MUTEX_HELD(&db->db_mtx)); 2218 2219 if (db->db_blkptr != NULL) 2220 return; 2221 2222 if (db->db_blkid == DMU_SPILL_BLKID) { 2223 db->db_blkptr = &dn->dn_phys->dn_spill; 2224 BP_ZERO(db->db_blkptr); 2225 return; 2226 } 2227 if (db->db_level == dn->dn_phys->dn_nlevels-1) { 2228 /* 2229 * This buffer was allocated at a time when there was 2230 * no available blkptrs from the dnode, or it was 2231 * inappropriate to hook it in (i.e., nlevels mis-match). 2232 */ 2233 ASSERT(db->db_blkid < dn->dn_phys->dn_nblkptr); 2234 ASSERT(db->db_parent == NULL); 2235 db->db_parent = dn->dn_dbuf; 2236 db->db_blkptr = &dn->dn_phys->dn_blkptr[db->db_blkid]; 2237 DBUF_VERIFY(db); 2238 } else { 2239 dmu_buf_impl_t *parent = db->db_parent; 2240 int epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT; 2241 2242 ASSERT(dn->dn_phys->dn_nlevels > 1); 2243 if (parent == NULL) { 2244 mutex_exit(&db->db_mtx); 2245 rw_enter(&dn->dn_struct_rwlock, RW_READER); 2246 (void) dbuf_hold_impl(dn, db->db_level+1, 2247 db->db_blkid >> epbs, FALSE, db, &parent); 2248 rw_exit(&dn->dn_struct_rwlock); 2249 mutex_enter(&db->db_mtx); 2250 db->db_parent = parent; 2251 } 2252 db->db_blkptr = (blkptr_t *)parent->db.db_data + 2253 (db->db_blkid & ((1ULL << epbs) - 1)); 2254 DBUF_VERIFY(db); 2255 } 2256 } 2257 2258 static void 2259 dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx) 2260 { 2261 dmu_buf_impl_t *db = dr->dr_dbuf; 2262 dnode_t *dn; 2263 zio_t *zio; 2264 2265 ASSERT(dmu_tx_is_syncing(tx)); 2266 2267 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr); 2268 2269 mutex_enter(&db->db_mtx); 2270 2271 ASSERT(db->db_level > 0); 2272 DBUF_VERIFY(db); 2273 2274 if (db->db_buf == NULL) { 2275 mutex_exit(&db->db_mtx); 2276 (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED); 2277 mutex_enter(&db->db_mtx); 2278 } 2279 ASSERT3U(db->db_state, ==, DB_CACHED); 2280 ASSERT(db->db_buf != NULL); 2281 2282 DB_DNODE_ENTER(db); 2283 dn = DB_DNODE(db); 2284 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift); 2285 dbuf_check_blkptr(dn, db); 2286 DB_DNODE_EXIT(db); 2287 2288 db->db_data_pending = dr; 2289 2290 mutex_exit(&db->db_mtx); 2291 dbuf_write(dr, db->db_buf, tx); 2292 2293 zio = dr->dr_zio; 2294 mutex_enter(&dr->dt.di.dr_mtx); 2295 dbuf_sync_list(&dr->dt.di.dr_children, tx); 2296 ASSERT(list_head(&dr->dt.di.dr_children) == NULL); 2297 mutex_exit(&dr->dt.di.dr_mtx); 2298 zio_nowait(zio); 2299 } 2300 2301 static void 2302 dbuf_sync_leaf(dbuf_dirty_record_t *dr, dmu_tx_t *tx) 2303 { 2304 arc_buf_t **datap = &dr->dt.dl.dr_data; 2305 dmu_buf_impl_t *db = dr->dr_dbuf; 2306 dnode_t *dn; 2307 objset_t *os; 2308 uint64_t txg = tx->tx_txg; 2309 2310 ASSERT(dmu_tx_is_syncing(tx)); 2311 2312 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr); 2313 2314 mutex_enter(&db->db_mtx); 2315 /* 2316 * To be synced, we must be dirtied. But we 2317 * might have been freed after the dirty. 2318 */ 2319 if (db->db_state == DB_UNCACHED) { 2320 /* This buffer has been freed since it was dirtied */ 2321 ASSERT(db->db.db_data == NULL); 2322 } else if (db->db_state == DB_FILL) { 2323 /* This buffer was freed and is now being re-filled */ 2324 ASSERT(db->db.db_data != dr->dt.dl.dr_data); 2325 } else { 2326 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_NOFILL); 2327 } 2328 DBUF_VERIFY(db); 2329 2330 DB_DNODE_ENTER(db); 2331 dn = DB_DNODE(db); 2332 2333 if (db->db_blkid == DMU_SPILL_BLKID) { 2334 mutex_enter(&dn->dn_mtx); 2335 dn->dn_phys->dn_flags |= DNODE_FLAG_SPILL_BLKPTR; 2336 mutex_exit(&dn->dn_mtx); 2337 } 2338 2339 /* 2340 * If this is a bonus buffer, simply copy the bonus data into the 2341 * dnode. It will be written out when the dnode is synced (and it 2342 * will be synced, since it must have been dirty for dbuf_sync to 2343 * be called). 2344 */ 2345 if (db->db_blkid == DMU_BONUS_BLKID) { 2346 dbuf_dirty_record_t **drp; 2347 2348 ASSERT(*datap != NULL); 2349 ASSERT0(db->db_level); 2350 ASSERT3U(dn->dn_phys->dn_bonuslen, <=, DN_MAX_BONUSLEN); 2351 bcopy(*datap, DN_BONUS(dn->dn_phys), dn->dn_phys->dn_bonuslen); 2352 DB_DNODE_EXIT(db); 2353 2354 if (*datap != db->db.db_data) { 2355 zio_buf_free(*datap, DN_MAX_BONUSLEN); 2356 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER); 2357 } 2358 db->db_data_pending = NULL; 2359 drp = &db->db_last_dirty; 2360 while (*drp != dr) 2361 drp = &(*drp)->dr_next; 2362 ASSERT(dr->dr_next == NULL); 2363 ASSERT(dr->dr_dbuf == db); 2364 *drp = dr->dr_next; 2365 kmem_free(dr, sizeof (dbuf_dirty_record_t)); 2366 ASSERT(db->db_dirtycnt > 0); 2367 db->db_dirtycnt -= 1; 2368 dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg); 2369 return; 2370 } 2371 2372 os = dn->dn_objset; 2373 2374 /* 2375 * This function may have dropped the db_mtx lock allowing a dmu_sync 2376 * operation to sneak in. As a result, we need to ensure that we 2377 * don't check the dr_override_state until we have returned from 2378 * dbuf_check_blkptr. 2379 */ 2380 dbuf_check_blkptr(dn, db); 2381 2382 /* 2383 * If this buffer is in the middle of an immediate write, 2384 * wait for the synchronous IO to complete. 2385 */ 2386 while (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC) { 2387 ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT); 2388 cv_wait(&db->db_changed, &db->db_mtx); 2389 ASSERT(dr->dt.dl.dr_override_state != DR_NOT_OVERRIDDEN); 2390 } 2391 2392 if (db->db_state != DB_NOFILL && 2393 dn->dn_object != DMU_META_DNODE_OBJECT && 2394 refcount_count(&db->db_holds) > 1 && 2395 dr->dt.dl.dr_override_state != DR_OVERRIDDEN && 2396 *datap == db->db_buf) { 2397 /* 2398 * If this buffer is currently "in use" (i.e., there 2399 * are active holds and db_data still references it), 2400 * then make a copy before we start the write so that 2401 * any modifications from the open txg will not leak 2402 * into this write. 2403 * 2404 * NOTE: this copy does not need to be made for 2405 * objects only modified in the syncing context (e.g. 2406 * DNONE_DNODE blocks). 2407 */ 2408 int blksz = arc_buf_size(*datap); 2409 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 2410 *datap = arc_buf_alloc(os->os_spa, blksz, db, type); 2411 bcopy(db->db.db_data, (*datap)->b_data, blksz); 2412 } 2413 db->db_data_pending = dr; 2414 2415 mutex_exit(&db->db_mtx); 2416 2417 dbuf_write(dr, *datap, tx); 2418 2419 ASSERT(!list_link_active(&dr->dr_dirty_node)); 2420 if (dn->dn_object == DMU_META_DNODE_OBJECT) { 2421 list_insert_tail(&dn->dn_dirty_records[txg&TXG_MASK], dr); 2422 DB_DNODE_EXIT(db); 2423 } else { 2424 /* 2425 * Although zio_nowait() does not "wait for an IO", it does 2426 * initiate the IO. If this is an empty write it seems plausible 2427 * that the IO could actually be completed before the nowait 2428 * returns. We need to DB_DNODE_EXIT() first in case 2429 * zio_nowait() invalidates the dbuf. 2430 */ 2431 DB_DNODE_EXIT(db); 2432 zio_nowait(dr->dr_zio); 2433 } 2434 } 2435 2436 void 2437 dbuf_sync_list(list_t *list, dmu_tx_t *tx) 2438 { 2439 dbuf_dirty_record_t *dr; 2440 2441 while (dr = list_head(list)) { 2442 if (dr->dr_zio != NULL) { 2443 /* 2444 * If we find an already initialized zio then we 2445 * are processing the meta-dnode, and we have finished. 2446 * The dbufs for all dnodes are put back on the list 2447 * during processing, so that we can zio_wait() 2448 * these IOs after initiating all child IOs. 2449 */ 2450 ASSERT3U(dr->dr_dbuf->db.db_object, ==, 2451 DMU_META_DNODE_OBJECT); 2452 break; 2453 } 2454 list_remove(list, dr); 2455 if (dr->dr_dbuf->db_level > 0) 2456 dbuf_sync_indirect(dr, tx); 2457 else 2458 dbuf_sync_leaf(dr, tx); 2459 } 2460 } 2461 2462 /* ARGSUSED */ 2463 static void 2464 dbuf_write_ready(zio_t *zio, arc_buf_t *buf, void *vdb) 2465 { 2466 dmu_buf_impl_t *db = vdb; 2467 dnode_t *dn; 2468 blkptr_t *bp = zio->io_bp; 2469 blkptr_t *bp_orig = &zio->io_bp_orig; 2470 spa_t *spa = zio->io_spa; 2471 int64_t delta; 2472 uint64_t fill = 0; 2473 int i; 2474 2475 ASSERT(db->db_blkptr == bp); 2476 2477 DB_DNODE_ENTER(db); 2478 dn = DB_DNODE(db); 2479 delta = bp_get_dsize_sync(spa, bp) - bp_get_dsize_sync(spa, bp_orig); 2480 dnode_diduse_space(dn, delta - zio->io_prev_space_delta); 2481 zio->io_prev_space_delta = delta; 2482 2483 if (BP_IS_HOLE(bp)) { 2484 ASSERT(bp->blk_fill == 0); 2485 DB_DNODE_EXIT(db); 2486 return; 2487 } 2488 2489 ASSERT((db->db_blkid != DMU_SPILL_BLKID && 2490 BP_GET_TYPE(bp) == dn->dn_type) || 2491 (db->db_blkid == DMU_SPILL_BLKID && 2492 BP_GET_TYPE(bp) == dn->dn_bonustype)); 2493 ASSERT(BP_GET_LEVEL(bp) == db->db_level); 2494 2495 mutex_enter(&db->db_mtx); 2496 2497 #ifdef ZFS_DEBUG 2498 if (db->db_blkid == DMU_SPILL_BLKID) { 2499 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR); 2500 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) && 2501 db->db_blkptr == &dn->dn_phys->dn_spill); 2502 } 2503 #endif 2504 2505 if (db->db_level == 0) { 2506 mutex_enter(&dn->dn_mtx); 2507 if (db->db_blkid > dn->dn_phys->dn_maxblkid && 2508 db->db_blkid != DMU_SPILL_BLKID) 2509 dn->dn_phys->dn_maxblkid = db->db_blkid; 2510 mutex_exit(&dn->dn_mtx); 2511 2512 if (dn->dn_type == DMU_OT_DNODE) { 2513 dnode_phys_t *dnp = db->db.db_data; 2514 for (i = db->db.db_size >> DNODE_SHIFT; i > 0; 2515 i--, dnp++) { 2516 if (dnp->dn_type != DMU_OT_NONE) 2517 fill++; 2518 } 2519 } else { 2520 fill = 1; 2521 } 2522 } else { 2523 blkptr_t *ibp = db->db.db_data; 2524 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift); 2525 for (i = db->db.db_size >> SPA_BLKPTRSHIFT; i > 0; i--, ibp++) { 2526 if (BP_IS_HOLE(ibp)) 2527 continue; 2528 fill += ibp->blk_fill; 2529 } 2530 } 2531 DB_DNODE_EXIT(db); 2532 2533 bp->blk_fill = fill; 2534 2535 mutex_exit(&db->db_mtx); 2536 } 2537 2538 /* ARGSUSED */ 2539 static void 2540 dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb) 2541 { 2542 dmu_buf_impl_t *db = vdb; 2543 blkptr_t *bp = zio->io_bp; 2544 blkptr_t *bp_orig = &zio->io_bp_orig; 2545 uint64_t txg = zio->io_txg; 2546 dbuf_dirty_record_t **drp, *dr; 2547 2548 ASSERT0(zio->io_error); 2549 ASSERT(db->db_blkptr == bp); 2550 2551 /* 2552 * For nopwrites and rewrites we ensure that the bp matches our 2553 * original and bypass all the accounting. 2554 */ 2555 if (zio->io_flags & (ZIO_FLAG_IO_REWRITE | ZIO_FLAG_NOPWRITE)) { 2556 ASSERT(BP_EQUAL(bp, bp_orig)); 2557 } else { 2558 objset_t *os; 2559 dsl_dataset_t *ds; 2560 dmu_tx_t *tx; 2561 2562 DB_GET_OBJSET(&os, db); 2563 ds = os->os_dsl_dataset; 2564 tx = os->os_synctx; 2565 2566 (void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE); 2567 dsl_dataset_block_born(ds, bp, tx); 2568 } 2569 2570 mutex_enter(&db->db_mtx); 2571 2572 DBUF_VERIFY(db); 2573 2574 drp = &db->db_last_dirty; 2575 while ((dr = *drp) != db->db_data_pending) 2576 drp = &dr->dr_next; 2577 ASSERT(!list_link_active(&dr->dr_dirty_node)); 2578 ASSERT(dr->dr_txg == txg); 2579 ASSERT(dr->dr_dbuf == db); 2580 ASSERT(dr->dr_next == NULL); 2581 *drp = dr->dr_next; 2582 2583 #ifdef ZFS_DEBUG 2584 if (db->db_blkid == DMU_SPILL_BLKID) { 2585 dnode_t *dn; 2586 2587 DB_DNODE_ENTER(db); 2588 dn = DB_DNODE(db); 2589 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR); 2590 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) && 2591 db->db_blkptr == &dn->dn_phys->dn_spill); 2592 DB_DNODE_EXIT(db); 2593 } 2594 #endif 2595 2596 if (db->db_level == 0) { 2597 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 2598 ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN); 2599 if (db->db_state != DB_NOFILL) { 2600 if (dr->dt.dl.dr_data != db->db_buf) 2601 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data, 2602 db) == 1); 2603 else if (!arc_released(db->db_buf)) 2604 arc_set_callback(db->db_buf, dbuf_do_evict, db); 2605 } 2606 } else { 2607 dnode_t *dn; 2608 2609 DB_DNODE_ENTER(db); 2610 dn = DB_DNODE(db); 2611 ASSERT(list_head(&dr->dt.di.dr_children) == NULL); 2612 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift); 2613 if (!BP_IS_HOLE(db->db_blkptr)) { 2614 int epbs = 2615 dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT; 2616 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==, 2617 db->db.db_size); 2618 ASSERT3U(dn->dn_phys->dn_maxblkid 2619 >> (db->db_level * epbs), >=, db->db_blkid); 2620 arc_set_callback(db->db_buf, dbuf_do_evict, db); 2621 } 2622 DB_DNODE_EXIT(db); 2623 mutex_destroy(&dr->dt.di.dr_mtx); 2624 list_destroy(&dr->dt.di.dr_children); 2625 } 2626 kmem_free(dr, sizeof (dbuf_dirty_record_t)); 2627 2628 cv_broadcast(&db->db_changed); 2629 ASSERT(db->db_dirtycnt > 0); 2630 db->db_dirtycnt -= 1; 2631 db->db_data_pending = NULL; 2632 dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg); 2633 } 2634 2635 static void 2636 dbuf_write_nofill_ready(zio_t *zio) 2637 { 2638 dbuf_write_ready(zio, NULL, zio->io_private); 2639 } 2640 2641 static void 2642 dbuf_write_nofill_done(zio_t *zio) 2643 { 2644 dbuf_write_done(zio, NULL, zio->io_private); 2645 } 2646 2647 static void 2648 dbuf_write_override_ready(zio_t *zio) 2649 { 2650 dbuf_dirty_record_t *dr = zio->io_private; 2651 dmu_buf_impl_t *db = dr->dr_dbuf; 2652 2653 dbuf_write_ready(zio, NULL, db); 2654 } 2655 2656 static void 2657 dbuf_write_override_done(zio_t *zio) 2658 { 2659 dbuf_dirty_record_t *dr = zio->io_private; 2660 dmu_buf_impl_t *db = dr->dr_dbuf; 2661 blkptr_t *obp = &dr->dt.dl.dr_overridden_by; 2662 2663 mutex_enter(&db->db_mtx); 2664 if (!BP_EQUAL(zio->io_bp, obp)) { 2665 if (!BP_IS_HOLE(obp)) 2666 dsl_free(spa_get_dsl(zio->io_spa), zio->io_txg, obp); 2667 arc_release(dr->dt.dl.dr_data, db); 2668 } 2669 mutex_exit(&db->db_mtx); 2670 2671 dbuf_write_done(zio, NULL, db); 2672 } 2673 2674 static void 2675 dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx) 2676 { 2677 dmu_buf_impl_t *db = dr->dr_dbuf; 2678 dnode_t *dn; 2679 objset_t *os; 2680 dmu_buf_impl_t *parent = db->db_parent; 2681 uint64_t txg = tx->tx_txg; 2682 zbookmark_t zb; 2683 zio_prop_t zp; 2684 zio_t *zio; 2685 int wp_flag = 0; 2686 2687 DB_DNODE_ENTER(db); 2688 dn = DB_DNODE(db); 2689 os = dn->dn_objset; 2690 2691 if (db->db_state != DB_NOFILL) { 2692 if (db->db_level > 0 || dn->dn_type == DMU_OT_DNODE) { 2693 /* 2694 * Private object buffers are released here rather 2695 * than in dbuf_dirty() since they are only modified 2696 * in the syncing context and we don't want the 2697 * overhead of making multiple copies of the data. 2698 */ 2699 if (BP_IS_HOLE(db->db_blkptr)) { 2700 arc_buf_thaw(data); 2701 } else { 2702 dbuf_release_bp(db); 2703 } 2704 } 2705 } 2706 2707 if (parent != dn->dn_dbuf) { 2708 ASSERT(parent && parent->db_data_pending); 2709 ASSERT(db->db_level == parent->db_level-1); 2710 ASSERT(arc_released(parent->db_buf)); 2711 zio = parent->db_data_pending->dr_zio; 2712 } else { 2713 ASSERT((db->db_level == dn->dn_phys->dn_nlevels-1 && 2714 db->db_blkid != DMU_SPILL_BLKID) || 2715 (db->db_blkid == DMU_SPILL_BLKID && db->db_level == 0)); 2716 if (db->db_blkid != DMU_SPILL_BLKID) 2717 ASSERT3P(db->db_blkptr, ==, 2718 &dn->dn_phys->dn_blkptr[db->db_blkid]); 2719 zio = dn->dn_zio; 2720 } 2721 2722 ASSERT(db->db_level == 0 || data == db->db_buf); 2723 ASSERT3U(db->db_blkptr->blk_birth, <=, txg); 2724 ASSERT(zio); 2725 2726 SET_BOOKMARK(&zb, os->os_dsl_dataset ? 2727 os->os_dsl_dataset->ds_object : DMU_META_OBJSET, 2728 db->db.db_object, db->db_level, db->db_blkid); 2729 2730 if (db->db_blkid == DMU_SPILL_BLKID) 2731 wp_flag = WP_SPILL; 2732 wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0; 2733 2734 dmu_write_policy(os, dn, db->db_level, wp_flag, &zp); 2735 DB_DNODE_EXIT(db); 2736 2737 if (db->db_level == 0 && dr->dt.dl.dr_override_state == DR_OVERRIDDEN) { 2738 ASSERT(db->db_state != DB_NOFILL); 2739 dr->dr_zio = zio_write(zio, os->os_spa, txg, 2740 db->db_blkptr, data->b_data, arc_buf_size(data), &zp, 2741 dbuf_write_override_ready, dbuf_write_override_done, dr, 2742 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb); 2743 mutex_enter(&db->db_mtx); 2744 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN; 2745 zio_write_override(dr->dr_zio, &dr->dt.dl.dr_overridden_by, 2746 dr->dt.dl.dr_copies, dr->dt.dl.dr_nopwrite); 2747 mutex_exit(&db->db_mtx); 2748 } else if (db->db_state == DB_NOFILL) { 2749 ASSERT(zp.zp_checksum == ZIO_CHECKSUM_OFF); 2750 dr->dr_zio = zio_write(zio, os->os_spa, txg, 2751 db->db_blkptr, NULL, db->db.db_size, &zp, 2752 dbuf_write_nofill_ready, dbuf_write_nofill_done, db, 2753 ZIO_PRIORITY_ASYNC_WRITE, 2754 ZIO_FLAG_MUSTSUCCEED | ZIO_FLAG_NODATA, &zb); 2755 } else { 2756 ASSERT(arc_released(data)); 2757 dr->dr_zio = arc_write(zio, os->os_spa, txg, 2758 db->db_blkptr, data, DBUF_IS_L2CACHEABLE(db), &zp, 2759 dbuf_write_ready, dbuf_write_done, db, 2760 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb); 2761 } 2762 }