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, 2018 by Delphix. All rights reserved. 25 * Copyright (c) 2013 by Saso Kiselkov. All rights reserved. 26 * Copyright (c) 2013, Joyent, Inc. All rights reserved. 27 * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved. 28 * Copyright (c) 2014 Integros [integros.com] 29 */ 30 31 #include <sys/zfs_context.h> 32 #include <sys/dmu.h> 33 #include <sys/dmu_send.h> 34 #include <sys/dmu_impl.h> 35 #include <sys/dbuf.h> 36 #include <sys/dmu_objset.h> 37 #include <sys/dsl_dataset.h> 38 #include <sys/dsl_dir.h> 39 #include <sys/dmu_tx.h> 40 #include <sys/spa.h> 41 #include <sys/zio.h> 42 #include <sys/dmu_zfetch.h> 43 #include <sys/sa.h> 44 #include <sys/sa_impl.h> 45 #include <sys/zfeature.h> 46 #include <sys/blkptr.h> 47 #include <sys/range_tree.h> 48 #include <sys/callb.h> 49 #include <sys/abd.h> 50 #include <sys/vdev.h> 51 #include <sys/cityhash.h> 52 #include <sys/spa_impl.h> 53 54 static boolean_t dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx); 55 static void dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx); 56 57 #ifndef __lint 58 extern inline void dmu_buf_init_user(dmu_buf_user_t *dbu, 59 dmu_buf_evict_func_t *evict_func_sync, 60 dmu_buf_evict_func_t *evict_func_async, 61 dmu_buf_t **clear_on_evict_dbufp); 62 #endif /* ! __lint */ 63 64 /* 65 * Global data structures and functions for the dbuf cache. 66 */ 67 static kmem_cache_t *dbuf_kmem_cache; 68 static taskq_t *dbu_evict_taskq; 69 70 static kthread_t *dbuf_cache_evict_thread; 71 static kmutex_t dbuf_evict_lock; 72 static kcondvar_t dbuf_evict_cv; 73 static boolean_t dbuf_evict_thread_exit; 74 75 /* 76 * There are two dbuf caches; each dbuf can only be in one of them at a time. 77 * 78 * 1. Cache of metadata dbufs, to help make read-heavy administrative commands 79 * from /sbin/zfs run faster. The "metadata cache" specifically stores dbufs 80 * that represent the metadata that describes filesystems/snapshots/ 81 * bookmarks/properties/etc. We only evict from this cache when we export a 82 * pool, to short-circuit as much I/O as possible for all administrative 83 * commands that need the metadata. There is no eviction policy for this 84 * cache, because we try to only include types in it which would occupy a 85 * very small amount of space per object but create a large impact on the 86 * performance of these commands. Instead, after it reaches a maximum size 87 * (which should only happen on very small memory systems with a very large 88 * number of filesystem objects), we stop taking new dbufs into the 89 * metadata cache, instead putting them in the normal dbuf cache. 90 * 91 * 2. LRU cache of dbufs. The "dbuf cache" maintains a list of dbufs that 92 * are not currently held but have been recently released. These dbufs 93 * are not eligible for arc eviction until they are aged out of the cache. 94 * Dbufs that are aged out of the cache will be immediately destroyed and 95 * become eligible for arc eviction. 96 * 97 * Dbufs are added to these caches once the last hold is released. If a dbuf is 98 * later accessed and still exists in the dbuf cache, then it will be removed 99 * from the cache and later re-added to the head of the cache. 100 * 101 * If a given dbuf meets the requirements for the metadata cache, it will go 102 * there, otherwise it will be considered for the generic LRU dbuf cache. The 103 * caches and the refcounts tracking their sizes are stored in an array indexed 104 * by those caches' matching enum values (from dbuf_cached_state_t). 105 */ 106 typedef struct dbuf_cache { 107 multilist_t *cache; 108 zfs_refcount_t size; 109 } dbuf_cache_t; 110 dbuf_cache_t dbuf_caches[DB_CACHE_MAX]; 111 112 /* Size limits for the caches */ 113 uint64_t dbuf_cache_max_bytes = 0; 114 uint64_t dbuf_metadata_cache_max_bytes = 0; 115 /* Set the default sizes of the caches to log2 fraction of arc size */ 116 int dbuf_cache_shift = 5; 117 int dbuf_metadata_cache_shift = 6; 118 119 /* 120 * For diagnostic purposes, this is incremented whenever we can't add 121 * something to the metadata cache because it's full, and instead put 122 * the data in the regular dbuf cache. 123 */ 124 uint64_t dbuf_metadata_cache_overflow; 125 126 /* 127 * The LRU dbuf cache uses a three-stage eviction policy: 128 * - A low water marker designates when the dbuf eviction thread 129 * should stop evicting from the dbuf cache. 130 * - When we reach the maximum size (aka mid water mark), we 131 * signal the eviction thread to run. 132 * - The high water mark indicates when the eviction thread 133 * is unable to keep up with the incoming load and eviction must 134 * happen in the context of the calling thread. 135 * 136 * The dbuf cache: 137 * (max size) 138 * low water mid water hi water 139 * +----------------------------------------+----------+----------+ 140 * | | | | 141 * | | | | 142 * | | | | 143 * | | | | 144 * +----------------------------------------+----------+----------+ 145 * stop signal evict 146 * evicting eviction directly 147 * thread 148 * 149 * The high and low water marks indicate the operating range for the eviction 150 * thread. The low water mark is, by default, 90% of the total size of the 151 * cache and the high water mark is at 110% (both of these percentages can be 152 * changed by setting dbuf_cache_lowater_pct and dbuf_cache_hiwater_pct, 153 * respectively). The eviction thread will try to ensure that the cache remains 154 * within this range by waking up every second and checking if the cache is 155 * above the low water mark. The thread can also be woken up by callers adding 156 * elements into the cache if the cache is larger than the mid water (i.e max 157 * cache size). Once the eviction thread is woken up and eviction is required, 158 * it will continue evicting buffers until it's able to reduce the cache size 159 * to the low water mark. If the cache size continues to grow and hits the high 160 * water mark, then callers adding elments to the cache will begin to evict 161 * directly from the cache until the cache is no longer above the high water 162 * mark. 163 */ 164 165 /* 166 * The percentage above and below the maximum cache size. 167 */ 168 uint_t dbuf_cache_hiwater_pct = 10; 169 uint_t dbuf_cache_lowater_pct = 10; 170 171 /* ARGSUSED */ 172 static int 173 dbuf_cons(void *vdb, void *unused, int kmflag) 174 { 175 dmu_buf_impl_t *db = vdb; 176 bzero(db, sizeof (dmu_buf_impl_t)); 177 178 mutex_init(&db->db_mtx, NULL, MUTEX_DEFAULT, NULL); 179 cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL); 180 multilist_link_init(&db->db_cache_link); 181 zfs_refcount_create(&db->db_holds); 182 183 return (0); 184 } 185 186 /* ARGSUSED */ 187 static void 188 dbuf_dest(void *vdb, void *unused) 189 { 190 dmu_buf_impl_t *db = vdb; 191 mutex_destroy(&db->db_mtx); 192 cv_destroy(&db->db_changed); 193 ASSERT(!multilist_link_active(&db->db_cache_link)); 194 zfs_refcount_destroy(&db->db_holds); 195 } 196 197 /* 198 * dbuf hash table routines 199 */ 200 static dbuf_hash_table_t dbuf_hash_table; 201 202 static uint64_t dbuf_hash_count; 203 204 /* 205 * We use Cityhash for this. It's fast, and has good hash properties without 206 * requiring any large static buffers. 207 */ 208 static uint64_t 209 dbuf_hash(void *os, uint64_t obj, uint8_t lvl, uint64_t blkid) 210 { 211 return (cityhash4((uintptr_t)os, obj, (uint64_t)lvl, blkid)); 212 } 213 214 #define DBUF_EQUAL(dbuf, os, obj, level, blkid) \ 215 ((dbuf)->db.db_object == (obj) && \ 216 (dbuf)->db_objset == (os) && \ 217 (dbuf)->db_level == (level) && \ 218 (dbuf)->db_blkid == (blkid)) 219 220 dmu_buf_impl_t * 221 dbuf_find(objset_t *os, uint64_t obj, uint8_t level, uint64_t blkid) 222 { 223 dbuf_hash_table_t *h = &dbuf_hash_table; 224 uint64_t hv = dbuf_hash(os, obj, level, blkid); 225 uint64_t idx = hv & h->hash_table_mask; 226 dmu_buf_impl_t *db; 227 228 mutex_enter(DBUF_HASH_MUTEX(h, idx)); 229 for (db = h->hash_table[idx]; db != NULL; db = db->db_hash_next) { 230 if (DBUF_EQUAL(db, os, obj, level, blkid)) { 231 mutex_enter(&db->db_mtx); 232 if (db->db_state != DB_EVICTING) { 233 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 234 return (db); 235 } 236 mutex_exit(&db->db_mtx); 237 } 238 } 239 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 240 return (NULL); 241 } 242 243 static dmu_buf_impl_t * 244 dbuf_find_bonus(objset_t *os, uint64_t object) 245 { 246 dnode_t *dn; 247 dmu_buf_impl_t *db = NULL; 248 249 if (dnode_hold(os, object, FTAG, &dn) == 0) { 250 rw_enter(&dn->dn_struct_rwlock, RW_READER); 251 if (dn->dn_bonus != NULL) { 252 db = dn->dn_bonus; 253 mutex_enter(&db->db_mtx); 254 } 255 rw_exit(&dn->dn_struct_rwlock); 256 dnode_rele(dn, FTAG); 257 } 258 return (db); 259 } 260 261 /* 262 * Insert an entry into the hash table. If there is already an element 263 * equal to elem in the hash table, then the already existing element 264 * will be returned and the new element will not be inserted. 265 * Otherwise returns NULL. 266 */ 267 static dmu_buf_impl_t * 268 dbuf_hash_insert(dmu_buf_impl_t *db) 269 { 270 dbuf_hash_table_t *h = &dbuf_hash_table; 271 objset_t *os = db->db_objset; 272 uint64_t obj = db->db.db_object; 273 int level = db->db_level; 274 uint64_t blkid = db->db_blkid; 275 uint64_t hv = dbuf_hash(os, obj, level, blkid); 276 uint64_t idx = hv & h->hash_table_mask; 277 dmu_buf_impl_t *dbf; 278 279 mutex_enter(DBUF_HASH_MUTEX(h, idx)); 280 for (dbf = h->hash_table[idx]; dbf != NULL; dbf = dbf->db_hash_next) { 281 if (DBUF_EQUAL(dbf, os, obj, level, blkid)) { 282 mutex_enter(&dbf->db_mtx); 283 if (dbf->db_state != DB_EVICTING) { 284 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 285 return (dbf); 286 } 287 mutex_exit(&dbf->db_mtx); 288 } 289 } 290 291 mutex_enter(&db->db_mtx); 292 db->db_hash_next = h->hash_table[idx]; 293 h->hash_table[idx] = db; 294 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 295 atomic_inc_64(&dbuf_hash_count); 296 297 return (NULL); 298 } 299 300 /* 301 * Remove an entry from the hash table. It must be in the EVICTING state. 302 */ 303 static void 304 dbuf_hash_remove(dmu_buf_impl_t *db) 305 { 306 dbuf_hash_table_t *h = &dbuf_hash_table; 307 uint64_t hv = dbuf_hash(db->db_objset, db->db.db_object, 308 db->db_level, db->db_blkid); 309 uint64_t idx = hv & h->hash_table_mask; 310 dmu_buf_impl_t *dbf, **dbp; 311 312 /* 313 * We musn't hold db_mtx to maintain lock ordering: 314 * DBUF_HASH_MUTEX > db_mtx. 315 */ 316 ASSERT(zfs_refcount_is_zero(&db->db_holds)); 317 ASSERT(db->db_state == DB_EVICTING); 318 ASSERT(!MUTEX_HELD(&db->db_mtx)); 319 320 mutex_enter(DBUF_HASH_MUTEX(h, idx)); 321 dbp = &h->hash_table[idx]; 322 while ((dbf = *dbp) != db) { 323 dbp = &dbf->db_hash_next; 324 ASSERT(dbf != NULL); 325 } 326 *dbp = db->db_hash_next; 327 db->db_hash_next = NULL; 328 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 329 atomic_dec_64(&dbuf_hash_count); 330 } 331 332 typedef enum { 333 DBVU_EVICTING, 334 DBVU_NOT_EVICTING 335 } dbvu_verify_type_t; 336 337 static void 338 dbuf_verify_user(dmu_buf_impl_t *db, dbvu_verify_type_t verify_type) 339 { 340 #ifdef ZFS_DEBUG 341 int64_t holds; 342 343 if (db->db_user == NULL) 344 return; 345 346 /* Only data blocks support the attachment of user data. */ 347 ASSERT(db->db_level == 0); 348 349 /* Clients must resolve a dbuf before attaching user data. */ 350 ASSERT(db->db.db_data != NULL); 351 ASSERT3U(db->db_state, ==, DB_CACHED); 352 353 holds = zfs_refcount_count(&db->db_holds); 354 if (verify_type == DBVU_EVICTING) { 355 /* 356 * Immediate eviction occurs when holds == dirtycnt. 357 * For normal eviction buffers, holds is zero on 358 * eviction, except when dbuf_fix_old_data() calls 359 * dbuf_clear_data(). However, the hold count can grow 360 * during eviction even though db_mtx is held (see 361 * dmu_bonus_hold() for an example), so we can only 362 * test the generic invariant that holds >= dirtycnt. 363 */ 364 ASSERT3U(holds, >=, db->db_dirtycnt); 365 } else { 366 if (db->db_user_immediate_evict == TRUE) 367 ASSERT3U(holds, >=, db->db_dirtycnt); 368 else 369 ASSERT3U(holds, >, 0); 370 } 371 #endif 372 } 373 374 static void 375 dbuf_evict_user(dmu_buf_impl_t *db) 376 { 377 dmu_buf_user_t *dbu = db->db_user; 378 379 ASSERT(MUTEX_HELD(&db->db_mtx)); 380 381 if (dbu == NULL) 382 return; 383 384 dbuf_verify_user(db, DBVU_EVICTING); 385 db->db_user = NULL; 386 387 #ifdef ZFS_DEBUG 388 if (dbu->dbu_clear_on_evict_dbufp != NULL) 389 *dbu->dbu_clear_on_evict_dbufp = NULL; 390 #endif 391 392 /* 393 * There are two eviction callbacks - one that we call synchronously 394 * and one that we invoke via a taskq. The async one is useful for 395 * avoiding lock order reversals and limiting stack depth. 396 * 397 * Note that if we have a sync callback but no async callback, 398 * it's likely that the sync callback will free the structure 399 * containing the dbu. In that case we need to take care to not 400 * dereference dbu after calling the sync evict func. 401 */ 402 boolean_t has_async = (dbu->dbu_evict_func_async != NULL); 403 404 if (dbu->dbu_evict_func_sync != NULL) 405 dbu->dbu_evict_func_sync(dbu); 406 407 if (has_async) { 408 taskq_dispatch_ent(dbu_evict_taskq, dbu->dbu_evict_func_async, 409 dbu, 0, &dbu->dbu_tqent); 410 } 411 } 412 413 boolean_t 414 dbuf_is_metadata(dmu_buf_impl_t *db) 415 { 416 if (db->db_level > 0) { 417 return (B_TRUE); 418 } else { 419 boolean_t is_metadata; 420 421 DB_DNODE_ENTER(db); 422 is_metadata = DMU_OT_IS_METADATA(DB_DNODE(db)->dn_type); 423 DB_DNODE_EXIT(db); 424 425 return (is_metadata); 426 } 427 } 428 429 /* 430 * This returns whether this dbuf should be stored in the metadata cache, which 431 * is based on whether it's from one of the dnode types that store data related 432 * to traversing dataset hierarchies. 433 */ 434 static boolean_t 435 dbuf_include_in_metadata_cache(dmu_buf_impl_t *db) 436 { 437 DB_DNODE_ENTER(db); 438 dmu_object_type_t type = DB_DNODE(db)->dn_type; 439 DB_DNODE_EXIT(db); 440 441 /* Check if this dbuf is one of the types we care about */ 442 if (DMU_OT_IS_METADATA_CACHED(type)) { 443 /* If we hit this, then we set something up wrong in dmu_ot */ 444 ASSERT(DMU_OT_IS_METADATA(type)); 445 446 /* 447 * Sanity check for small-memory systems: don't allocate too 448 * much memory for this purpose. 449 */ 450 if (zfs_refcount_count( 451 &dbuf_caches[DB_DBUF_METADATA_CACHE].size) > 452 dbuf_metadata_cache_max_bytes) { 453 dbuf_metadata_cache_overflow++; 454 DTRACE_PROBE1(dbuf__metadata__cache__overflow, 455 dmu_buf_impl_t *, db); 456 return (B_FALSE); 457 } 458 459 return (B_TRUE); 460 } 461 462 return (B_FALSE); 463 } 464 465 /* 466 * This function *must* return indices evenly distributed between all 467 * sublists of the multilist. This is needed due to how the dbuf eviction 468 * code is laid out; dbuf_evict_thread() assumes dbufs are evenly 469 * distributed between all sublists and uses this assumption when 470 * deciding which sublist to evict from and how much to evict from it. 471 */ 472 unsigned int 473 dbuf_cache_multilist_index_func(multilist_t *ml, void *obj) 474 { 475 dmu_buf_impl_t *db = obj; 476 477 /* 478 * The assumption here, is the hash value for a given 479 * dmu_buf_impl_t will remain constant throughout it's lifetime 480 * (i.e. it's objset, object, level and blkid fields don't change). 481 * Thus, we don't need to store the dbuf's sublist index 482 * on insertion, as this index can be recalculated on removal. 483 * 484 * Also, the low order bits of the hash value are thought to be 485 * distributed evenly. Otherwise, in the case that the multilist 486 * has a power of two number of sublists, each sublists' usage 487 * would not be evenly distributed. 488 */ 489 return (dbuf_hash(db->db_objset, db->db.db_object, 490 db->db_level, db->db_blkid) % 491 multilist_get_num_sublists(ml)); 492 } 493 494 static inline boolean_t 495 dbuf_cache_above_hiwater(void) 496 { 497 uint64_t dbuf_cache_hiwater_bytes = 498 (dbuf_cache_max_bytes * dbuf_cache_hiwater_pct) / 100; 499 500 return (zfs_refcount_count(&dbuf_caches[DB_DBUF_CACHE].size) > 501 dbuf_cache_max_bytes + dbuf_cache_hiwater_bytes); 502 } 503 504 static inline boolean_t 505 dbuf_cache_above_lowater(void) 506 { 507 uint64_t dbuf_cache_lowater_bytes = 508 (dbuf_cache_max_bytes * dbuf_cache_lowater_pct) / 100; 509 510 return (zfs_refcount_count(&dbuf_caches[DB_DBUF_CACHE].size) > 511 dbuf_cache_max_bytes - dbuf_cache_lowater_bytes); 512 } 513 514 /* 515 * Evict the oldest eligible dbuf from the dbuf cache. 516 */ 517 static void 518 dbuf_evict_one(void) 519 { 520 int idx = multilist_get_random_index(dbuf_caches[DB_DBUF_CACHE].cache); 521 multilist_sublist_t *mls = multilist_sublist_lock( 522 dbuf_caches[DB_DBUF_CACHE].cache, idx); 523 524 ASSERT(!MUTEX_HELD(&dbuf_evict_lock)); 525 526 dmu_buf_impl_t *db = multilist_sublist_tail(mls); 527 while (db != NULL && mutex_tryenter(&db->db_mtx) == 0) { 528 db = multilist_sublist_prev(mls, db); 529 } 530 531 DTRACE_PROBE2(dbuf__evict__one, dmu_buf_impl_t *, db, 532 multilist_sublist_t *, mls); 533 534 if (db != NULL) { 535 multilist_sublist_remove(mls, db); 536 multilist_sublist_unlock(mls); 537 (void) zfs_refcount_remove_many( 538 &dbuf_caches[DB_DBUF_CACHE].size, 539 db->db.db_size, db); 540 ASSERT3U(db->db_caching_status, ==, DB_DBUF_CACHE); 541 db->db_caching_status = DB_NO_CACHE; 542 dbuf_destroy(db); 543 } else { 544 multilist_sublist_unlock(mls); 545 } 546 } 547 548 /* 549 * The dbuf evict thread is responsible for aging out dbufs from the 550 * cache. Once the cache has reached it's maximum size, dbufs are removed 551 * and destroyed. The eviction thread will continue running until the size 552 * of the dbuf cache is at or below the maximum size. Once the dbuf is aged 553 * out of the cache it is destroyed and becomes eligible for arc eviction. 554 */ 555 /* ARGSUSED */ 556 static void 557 dbuf_evict_thread(void *unused) 558 { 559 callb_cpr_t cpr; 560 561 CALLB_CPR_INIT(&cpr, &dbuf_evict_lock, callb_generic_cpr, FTAG); 562 563 mutex_enter(&dbuf_evict_lock); 564 while (!dbuf_evict_thread_exit) { 565 while (!dbuf_cache_above_lowater() && !dbuf_evict_thread_exit) { 566 CALLB_CPR_SAFE_BEGIN(&cpr); 567 (void) cv_timedwait_hires(&dbuf_evict_cv, 568 &dbuf_evict_lock, SEC2NSEC(1), MSEC2NSEC(1), 0); 569 CALLB_CPR_SAFE_END(&cpr, &dbuf_evict_lock); 570 } 571 mutex_exit(&dbuf_evict_lock); 572 573 /* 574 * Keep evicting as long as we're above the low water mark 575 * for the cache. We do this without holding the locks to 576 * minimize lock contention. 577 */ 578 while (dbuf_cache_above_lowater() && !dbuf_evict_thread_exit) { 579 dbuf_evict_one(); 580 } 581 582 mutex_enter(&dbuf_evict_lock); 583 } 584 585 dbuf_evict_thread_exit = B_FALSE; 586 cv_broadcast(&dbuf_evict_cv); 587 CALLB_CPR_EXIT(&cpr); /* drops dbuf_evict_lock */ 588 thread_exit(); 589 } 590 591 /* 592 * Wake up the dbuf eviction thread if the dbuf cache is at its max size. 593 * If the dbuf cache is at its high water mark, then evict a dbuf from the 594 * dbuf cache using the callers context. 595 */ 596 static void 597 dbuf_evict_notify(void) 598 { 599 /* 600 * We check if we should evict without holding the dbuf_evict_lock, 601 * because it's OK to occasionally make the wrong decision here, 602 * and grabbing the lock results in massive lock contention. 603 */ 604 if (zfs_refcount_count(&dbuf_caches[DB_DBUF_CACHE].size) > 605 dbuf_cache_max_bytes) { 606 if (dbuf_cache_above_hiwater()) 607 dbuf_evict_one(); 608 cv_signal(&dbuf_evict_cv); 609 } 610 } 611 612 void 613 dbuf_init(void) 614 { 615 uint64_t hsize = 1ULL << 16; 616 dbuf_hash_table_t *h = &dbuf_hash_table; 617 int i; 618 619 /* 620 * The hash table is big enough to fill all of physical memory 621 * with an average 4K block size. The table will take up 622 * totalmem*sizeof(void*)/4K (i.e. 2MB/GB with 8-byte pointers). 623 */ 624 while (hsize * 4096 < physmem * PAGESIZE) 625 hsize <<= 1; 626 627 retry: 628 h->hash_table_mask = hsize - 1; 629 h->hash_table = kmem_zalloc(hsize * sizeof (void *), KM_NOSLEEP); 630 if (h->hash_table == NULL) { 631 /* XXX - we should really return an error instead of assert */ 632 ASSERT(hsize > (1ULL << 10)); 633 hsize >>= 1; 634 goto retry; 635 } 636 637 dbuf_kmem_cache = kmem_cache_create("dmu_buf_impl_t", 638 sizeof (dmu_buf_impl_t), 639 0, dbuf_cons, dbuf_dest, NULL, NULL, NULL, 0); 640 641 for (i = 0; i < DBUF_MUTEXES; i++) 642 mutex_init(&h->hash_mutexes[i], NULL, MUTEX_DEFAULT, NULL); 643 644 /* 645 * Setup the parameters for the dbuf caches. We set the sizes of the 646 * dbuf cache and the metadata cache to 1/32nd and 1/16th (default) 647 * of the size of the ARC, respectively. If the values are set in 648 * /etc/system and they're not greater than the size of the ARC, then 649 * we honor that value. 650 */ 651 if (dbuf_cache_max_bytes == 0 || 652 dbuf_cache_max_bytes >= arc_max_bytes()) { 653 dbuf_cache_max_bytes = arc_max_bytes() >> dbuf_cache_shift; 654 } 655 if (dbuf_metadata_cache_max_bytes == 0 || 656 dbuf_metadata_cache_max_bytes >= arc_max_bytes()) { 657 dbuf_metadata_cache_max_bytes = 658 arc_max_bytes() >> dbuf_metadata_cache_shift; 659 } 660 661 /* 662 * All entries are queued via taskq_dispatch_ent(), so min/maxalloc 663 * configuration is not required. 664 */ 665 dbu_evict_taskq = taskq_create("dbu_evict", 1, minclsyspri, 0, 0, 0); 666 667 for (dbuf_cached_state_t dcs = 0; dcs < DB_CACHE_MAX; dcs++) { 668 dbuf_caches[dcs].cache = 669 multilist_create(sizeof (dmu_buf_impl_t), 670 offsetof(dmu_buf_impl_t, db_cache_link), 671 dbuf_cache_multilist_index_func); 672 zfs_refcount_create(&dbuf_caches[dcs].size); 673 } 674 675 dbuf_evict_thread_exit = B_FALSE; 676 mutex_init(&dbuf_evict_lock, NULL, MUTEX_DEFAULT, NULL); 677 cv_init(&dbuf_evict_cv, NULL, CV_DEFAULT, NULL); 678 dbuf_cache_evict_thread = thread_create(NULL, 0, dbuf_evict_thread, 679 NULL, 0, &p0, TS_RUN, minclsyspri); 680 } 681 682 void 683 dbuf_fini(void) 684 { 685 dbuf_hash_table_t *h = &dbuf_hash_table; 686 int i; 687 688 for (i = 0; i < DBUF_MUTEXES; i++) 689 mutex_destroy(&h->hash_mutexes[i]); 690 kmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *)); 691 kmem_cache_destroy(dbuf_kmem_cache); 692 taskq_destroy(dbu_evict_taskq); 693 694 mutex_enter(&dbuf_evict_lock); 695 dbuf_evict_thread_exit = B_TRUE; 696 while (dbuf_evict_thread_exit) { 697 cv_signal(&dbuf_evict_cv); 698 cv_wait(&dbuf_evict_cv, &dbuf_evict_lock); 699 } 700 mutex_exit(&dbuf_evict_lock); 701 702 mutex_destroy(&dbuf_evict_lock); 703 cv_destroy(&dbuf_evict_cv); 704 705 for (dbuf_cached_state_t dcs = 0; dcs < DB_CACHE_MAX; dcs++) { 706 zfs_refcount_destroy(&dbuf_caches[dcs].size); 707 multilist_destroy(dbuf_caches[dcs].cache); 708 } 709 } 710 711 /* 712 * Other stuff. 713 */ 714 715 #ifdef ZFS_DEBUG 716 static void 717 dbuf_verify(dmu_buf_impl_t *db) 718 { 719 dnode_t *dn; 720 dbuf_dirty_record_t *dr; 721 722 ASSERT(MUTEX_HELD(&db->db_mtx)); 723 724 if (!(zfs_flags & ZFS_DEBUG_DBUF_VERIFY)) 725 return; 726 727 ASSERT(db->db_objset != NULL); 728 DB_DNODE_ENTER(db); 729 dn = DB_DNODE(db); 730 if (dn == NULL) { 731 ASSERT(db->db_parent == NULL); 732 ASSERT(db->db_blkptr == NULL); 733 } else { 734 ASSERT3U(db->db.db_object, ==, dn->dn_object); 735 ASSERT3P(db->db_objset, ==, dn->dn_objset); 736 ASSERT3U(db->db_level, <, dn->dn_nlevels); 737 ASSERT(db->db_blkid == DMU_BONUS_BLKID || 738 db->db_blkid == DMU_SPILL_BLKID || 739 !avl_is_empty(&dn->dn_dbufs)); 740 } 741 if (db->db_blkid == DMU_BONUS_BLKID) { 742 ASSERT(dn != NULL); 743 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen); 744 ASSERT3U(db->db.db_offset, ==, DMU_BONUS_BLKID); 745 } else if (db->db_blkid == DMU_SPILL_BLKID) { 746 ASSERT(dn != NULL); 747 ASSERT0(db->db.db_offset); 748 } else { 749 ASSERT3U(db->db.db_offset, ==, db->db_blkid * db->db.db_size); 750 } 751 752 for (dr = db->db_data_pending; dr != NULL; dr = dr->dr_next) 753 ASSERT(dr->dr_dbuf == db); 754 755 for (dr = db->db_last_dirty; dr != NULL; dr = dr->dr_next) 756 ASSERT(dr->dr_dbuf == db); 757 758 /* 759 * We can't assert that db_size matches dn_datablksz because it 760 * can be momentarily different when another thread is doing 761 * dnode_set_blksz(). 762 */ 763 if (db->db_level == 0 && db->db.db_object == DMU_META_DNODE_OBJECT) { 764 dr = db->db_data_pending; 765 /* 766 * It should only be modified in syncing context, so 767 * make sure we only have one copy of the data. 768 */ 769 ASSERT(dr == NULL || dr->dt.dl.dr_data == db->db_buf); 770 } 771 772 /* verify db->db_blkptr */ 773 if (db->db_blkptr) { 774 if (db->db_parent == dn->dn_dbuf) { 775 /* db is pointed to by the dnode */ 776 /* ASSERT3U(db->db_blkid, <, dn->dn_nblkptr); */ 777 if (DMU_OBJECT_IS_SPECIAL(db->db.db_object)) 778 ASSERT(db->db_parent == NULL); 779 else 780 ASSERT(db->db_parent != NULL); 781 if (db->db_blkid != DMU_SPILL_BLKID) 782 ASSERT3P(db->db_blkptr, ==, 783 &dn->dn_phys->dn_blkptr[db->db_blkid]); 784 } else { 785 /* db is pointed to by an indirect block */ 786 int epb = db->db_parent->db.db_size >> SPA_BLKPTRSHIFT; 787 ASSERT3U(db->db_parent->db_level, ==, db->db_level+1); 788 ASSERT3U(db->db_parent->db.db_object, ==, 789 db->db.db_object); 790 /* 791 * dnode_grow_indblksz() can make this fail if we don't 792 * have the struct_rwlock. XXX indblksz no longer 793 * grows. safe to do this now? 794 */ 795 if (RW_WRITE_HELD(&dn->dn_struct_rwlock)) { 796 ASSERT3P(db->db_blkptr, ==, 797 ((blkptr_t *)db->db_parent->db.db_data + 798 db->db_blkid % epb)); 799 } 800 } 801 } 802 if ((db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr)) && 803 (db->db_buf == NULL || db->db_buf->b_data) && 804 db->db.db_data && db->db_blkid != DMU_BONUS_BLKID && 805 db->db_state != DB_FILL && !dn->dn_free_txg) { 806 /* 807 * If the blkptr isn't set but they have nonzero data, 808 * it had better be dirty, otherwise we'll lose that 809 * data when we evict this buffer. 810 * 811 * There is an exception to this rule for indirect blocks; in 812 * this case, if the indirect block is a hole, we fill in a few 813 * fields on each of the child blocks (importantly, birth time) 814 * to prevent hole birth times from being lost when you 815 * partially fill in a hole. 816 */ 817 if (db->db_dirtycnt == 0) { 818 if (db->db_level == 0) { 819 uint64_t *buf = db->db.db_data; 820 int i; 821 822 for (i = 0; i < db->db.db_size >> 3; i++) { 823 ASSERT(buf[i] == 0); 824 } 825 } else { 826 blkptr_t *bps = db->db.db_data; 827 ASSERT3U(1 << DB_DNODE(db)->dn_indblkshift, ==, 828 db->db.db_size); 829 /* 830 * We want to verify that all the blkptrs in the 831 * indirect block are holes, but we may have 832 * automatically set up a few fields for them. 833 * We iterate through each blkptr and verify 834 * they only have those fields set. 835 */ 836 for (int i = 0; 837 i < db->db.db_size / sizeof (blkptr_t); 838 i++) { 839 blkptr_t *bp = &bps[i]; 840 ASSERT(ZIO_CHECKSUM_IS_ZERO( 841 &bp->blk_cksum)); 842 ASSERT( 843 DVA_IS_EMPTY(&bp->blk_dva[0]) && 844 DVA_IS_EMPTY(&bp->blk_dva[1]) && 845 DVA_IS_EMPTY(&bp->blk_dva[2])); 846 ASSERT0(bp->blk_fill); 847 ASSERT0(bp->blk_pad[0]); 848 ASSERT0(bp->blk_pad[1]); 849 ASSERT(!BP_IS_EMBEDDED(bp)); 850 ASSERT(BP_IS_HOLE(bp)); 851 ASSERT0(bp->blk_phys_birth); 852 } 853 } 854 } 855 } 856 DB_DNODE_EXIT(db); 857 } 858 #endif 859 860 static void 861 dbuf_clear_data(dmu_buf_impl_t *db) 862 { 863 ASSERT(MUTEX_HELD(&db->db_mtx)); 864 dbuf_evict_user(db); 865 ASSERT3P(db->db_buf, ==, NULL); 866 db->db.db_data = NULL; 867 if (db->db_state != DB_NOFILL) 868 db->db_state = DB_UNCACHED; 869 } 870 871 static void 872 dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf) 873 { 874 ASSERT(MUTEX_HELD(&db->db_mtx)); 875 ASSERT(buf != NULL); 876 877 db->db_buf = buf; 878 ASSERT(buf->b_data != NULL); 879 db->db.db_data = buf->b_data; 880 } 881 882 /* 883 * Loan out an arc_buf for read. Return the loaned arc_buf. 884 */ 885 arc_buf_t * 886 dbuf_loan_arcbuf(dmu_buf_impl_t *db) 887 { 888 arc_buf_t *abuf; 889 890 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 891 mutex_enter(&db->db_mtx); 892 if (arc_released(db->db_buf) || zfs_refcount_count(&db->db_holds) > 1) { 893 int blksz = db->db.db_size; 894 spa_t *spa = db->db_objset->os_spa; 895 896 mutex_exit(&db->db_mtx); 897 abuf = arc_loan_buf(spa, B_FALSE, blksz); 898 bcopy(db->db.db_data, abuf->b_data, blksz); 899 } else { 900 abuf = db->db_buf; 901 arc_loan_inuse_buf(abuf, db); 902 db->db_buf = NULL; 903 dbuf_clear_data(db); 904 mutex_exit(&db->db_mtx); 905 } 906 return (abuf); 907 } 908 909 /* 910 * Calculate which level n block references the data at the level 0 offset 911 * provided. 912 */ 913 uint64_t 914 dbuf_whichblock(dnode_t *dn, int64_t level, uint64_t offset) 915 { 916 if (dn->dn_datablkshift != 0 && dn->dn_indblkshift != 0) { 917 /* 918 * The level n blkid is equal to the level 0 blkid divided by 919 * the number of level 0s in a level n block. 920 * 921 * The level 0 blkid is offset >> datablkshift = 922 * offset / 2^datablkshift. 923 * 924 * The number of level 0s in a level n is the number of block 925 * pointers in an indirect block, raised to the power of level. 926 * This is 2^(indblkshift - SPA_BLKPTRSHIFT)^level = 927 * 2^(level*(indblkshift - SPA_BLKPTRSHIFT)). 928 * 929 * Thus, the level n blkid is: offset / 930 * ((2^datablkshift)*(2^(level*(indblkshift - SPA_BLKPTRSHIFT))) 931 * = offset / 2^(datablkshift + level * 932 * (indblkshift - SPA_BLKPTRSHIFT)) 933 * = offset >> (datablkshift + level * 934 * (indblkshift - SPA_BLKPTRSHIFT)) 935 */ 936 return (offset >> (dn->dn_datablkshift + level * 937 (dn->dn_indblkshift - SPA_BLKPTRSHIFT))); 938 } else { 939 ASSERT3U(offset, <, dn->dn_datablksz); 940 return (0); 941 } 942 } 943 944 static void 945 dbuf_read_done(zio_t *zio, arc_buf_t *buf, void *vdb) 946 { 947 dmu_buf_impl_t *db = vdb; 948 949 mutex_enter(&db->db_mtx); 950 ASSERT3U(db->db_state, ==, DB_READ); 951 /* 952 * All reads are synchronous, so we must have a hold on the dbuf 953 */ 954 ASSERT(zfs_refcount_count(&db->db_holds) > 0); 955 ASSERT(db->db_buf == NULL); 956 ASSERT(db->db.db_data == NULL); 957 if (buf == NULL) { 958 /* i/o error */ 959 ASSERT(zio == NULL || zio->io_error != 0); 960 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 961 ASSERT3P(db->db_buf, ==, NULL); 962 db->db_state = DB_UNCACHED; 963 } else if (db->db_level == 0 && db->db_freed_in_flight) { 964 /* freed in flight */ 965 ASSERT(zio == NULL || zio->io_error == 0); 966 arc_release(buf, db); 967 bzero(buf->b_data, db->db.db_size); 968 arc_buf_freeze(buf); 969 db->db_freed_in_flight = FALSE; 970 dbuf_set_data(db, buf); 971 db->db_state = DB_CACHED; 972 } else { 973 /* success */ 974 ASSERT(zio == NULL || zio->io_error == 0); 975 dbuf_set_data(db, buf); 976 db->db_state = DB_CACHED; 977 } 978 cv_broadcast(&db->db_changed); 979 dbuf_rele_and_unlock(db, NULL, B_FALSE); 980 } 981 982 static void 983 dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags) 984 { 985 dnode_t *dn; 986 zbookmark_phys_t zb; 987 arc_flags_t aflags = ARC_FLAG_NOWAIT; 988 989 DB_DNODE_ENTER(db); 990 dn = DB_DNODE(db); 991 ASSERT(!zfs_refcount_is_zero(&db->db_holds)); 992 /* We need the struct_rwlock to prevent db_blkptr from changing. */ 993 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 994 ASSERT(MUTEX_HELD(&db->db_mtx)); 995 ASSERT(db->db_state == DB_UNCACHED); 996 ASSERT(db->db_buf == NULL); 997 998 if (db->db_blkid == DMU_BONUS_BLKID) { 999 /* 1000 * The bonus length stored in the dnode may be less than 1001 * the maximum available space in the bonus buffer. 1002 */ 1003 int bonuslen = MIN(dn->dn_bonuslen, dn->dn_phys->dn_bonuslen); 1004 int max_bonuslen = DN_SLOTS_TO_BONUSLEN(dn->dn_num_slots); 1005 1006 ASSERT3U(bonuslen, <=, db->db.db_size); 1007 db->db.db_data = zio_buf_alloc(max_bonuslen); 1008 arc_space_consume(max_bonuslen, ARC_SPACE_BONUS); 1009 if (bonuslen < max_bonuslen) 1010 bzero(db->db.db_data, max_bonuslen); 1011 if (bonuslen) 1012 bcopy(DN_BONUS(dn->dn_phys), db->db.db_data, bonuslen); 1013 DB_DNODE_EXIT(db); 1014 db->db_state = DB_CACHED; 1015 mutex_exit(&db->db_mtx); 1016 return; 1017 } 1018 1019 /* 1020 * Recheck BP_IS_HOLE() after dnode_block_freed() in case dnode_sync() 1021 * processes the delete record and clears the bp while we are waiting 1022 * for the dn_mtx (resulting in a "no" from block_freed). 1023 */ 1024 if (db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr) || 1025 (db->db_level == 0 && (dnode_block_freed(dn, db->db_blkid) || 1026 BP_IS_HOLE(db->db_blkptr)))) { 1027 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 1028 1029 dbuf_set_data(db, arc_alloc_buf(db->db_objset->os_spa, db, type, 1030 db->db.db_size)); 1031 bzero(db->db.db_data, db->db.db_size); 1032 1033 if (db->db_blkptr != NULL && db->db_level > 0 && 1034 BP_IS_HOLE(db->db_blkptr) && 1035 db->db_blkptr->blk_birth != 0) { 1036 blkptr_t *bps = db->db.db_data; 1037 for (int i = 0; i < ((1 << 1038 DB_DNODE(db)->dn_indblkshift) / sizeof (blkptr_t)); 1039 i++) { 1040 blkptr_t *bp = &bps[i]; 1041 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==, 1042 1 << dn->dn_indblkshift); 1043 BP_SET_LSIZE(bp, 1044 BP_GET_LEVEL(db->db_blkptr) == 1 ? 1045 dn->dn_datablksz : 1046 BP_GET_LSIZE(db->db_blkptr)); 1047 BP_SET_TYPE(bp, BP_GET_TYPE(db->db_blkptr)); 1048 BP_SET_LEVEL(bp, 1049 BP_GET_LEVEL(db->db_blkptr) - 1); 1050 BP_SET_BIRTH(bp, db->db_blkptr->blk_birth, 0); 1051 } 1052 } 1053 DB_DNODE_EXIT(db); 1054 db->db_state = DB_CACHED; 1055 mutex_exit(&db->db_mtx); 1056 return; 1057 } 1058 1059 DB_DNODE_EXIT(db); 1060 1061 db->db_state = DB_READ; 1062 mutex_exit(&db->db_mtx); 1063 1064 if (DBUF_IS_L2CACHEABLE(db)) 1065 aflags |= ARC_FLAG_L2CACHE; 1066 1067 SET_BOOKMARK(&zb, db->db_objset->os_dsl_dataset ? 1068 db->db_objset->os_dsl_dataset->ds_object : DMU_META_OBJSET, 1069 db->db.db_object, db->db_level, db->db_blkid); 1070 1071 dbuf_add_ref(db, NULL); 1072 1073 (void) arc_read(zio, db->db_objset->os_spa, db->db_blkptr, 1074 dbuf_read_done, db, ZIO_PRIORITY_SYNC_READ, 1075 (flags & DB_RF_CANFAIL) ? ZIO_FLAG_CANFAIL : ZIO_FLAG_MUSTSUCCEED, 1076 &aflags, &zb); 1077 } 1078 1079 /* 1080 * This is our just-in-time copy function. It makes a copy of buffers that 1081 * have been modified in a previous transaction group before we access them in 1082 * the current active group. 1083 * 1084 * This function is used in three places: when we are dirtying a buffer for the 1085 * first time in a txg, when we are freeing a range in a dnode that includes 1086 * this buffer, and when we are accessing a buffer which was received compressed 1087 * and later referenced in a WRITE_BYREF record. 1088 * 1089 * Note that when we are called from dbuf_free_range() we do not put a hold on 1090 * the buffer, we just traverse the active dbuf list for the dnode. 1091 */ 1092 static void 1093 dbuf_fix_old_data(dmu_buf_impl_t *db, uint64_t txg) 1094 { 1095 dbuf_dirty_record_t *dr = db->db_last_dirty; 1096 1097 ASSERT(MUTEX_HELD(&db->db_mtx)); 1098 ASSERT(db->db.db_data != NULL); 1099 ASSERT(db->db_level == 0); 1100 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT); 1101 1102 if (dr == NULL || 1103 (dr->dt.dl.dr_data != 1104 ((db->db_blkid == DMU_BONUS_BLKID) ? db->db.db_data : db->db_buf))) 1105 return; 1106 1107 /* 1108 * If the last dirty record for this dbuf has not yet synced 1109 * and its referencing the dbuf data, either: 1110 * reset the reference to point to a new copy, 1111 * or (if there a no active holders) 1112 * just null out the current db_data pointer. 1113 */ 1114 ASSERT(dr->dr_txg >= txg - 2); 1115 if (db->db_blkid == DMU_BONUS_BLKID) { 1116 /* Note that the data bufs here are zio_bufs */ 1117 dnode_t *dn = DB_DNODE(db); 1118 int bonuslen = DN_SLOTS_TO_BONUSLEN(dn->dn_num_slots); 1119 dr->dt.dl.dr_data = zio_buf_alloc(bonuslen); 1120 arc_space_consume(bonuslen, ARC_SPACE_BONUS); 1121 bcopy(db->db.db_data, dr->dt.dl.dr_data, bonuslen); 1122 } else if (zfs_refcount_count(&db->db_holds) > db->db_dirtycnt) { 1123 int size = arc_buf_size(db->db_buf); 1124 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 1125 spa_t *spa = db->db_objset->os_spa; 1126 enum zio_compress compress_type = 1127 arc_get_compression(db->db_buf); 1128 1129 if (compress_type == ZIO_COMPRESS_OFF) { 1130 dr->dt.dl.dr_data = arc_alloc_buf(spa, db, type, size); 1131 } else { 1132 ASSERT3U(type, ==, ARC_BUFC_DATA); 1133 dr->dt.dl.dr_data = arc_alloc_compressed_buf(spa, db, 1134 size, arc_buf_lsize(db->db_buf), compress_type); 1135 } 1136 bcopy(db->db.db_data, dr->dt.dl.dr_data->b_data, size); 1137 } else { 1138 db->db_buf = NULL; 1139 dbuf_clear_data(db); 1140 } 1141 } 1142 1143 int 1144 dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags) 1145 { 1146 int err = 0; 1147 boolean_t prefetch; 1148 dnode_t *dn; 1149 1150 /* 1151 * We don't have to hold the mutex to check db_state because it 1152 * can't be freed while we have a hold on the buffer. 1153 */ 1154 ASSERT(!zfs_refcount_is_zero(&db->db_holds)); 1155 1156 if (db->db_state == DB_NOFILL) 1157 return (SET_ERROR(EIO)); 1158 1159 DB_DNODE_ENTER(db); 1160 dn = DB_DNODE(db); 1161 if ((flags & DB_RF_HAVESTRUCT) == 0) 1162 rw_enter(&dn->dn_struct_rwlock, RW_READER); 1163 1164 prefetch = db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID && 1165 (flags & DB_RF_NOPREFETCH) == 0 && dn != NULL && 1166 DBUF_IS_CACHEABLE(db); 1167 1168 mutex_enter(&db->db_mtx); 1169 if (db->db_state == DB_CACHED) { 1170 /* 1171 * If the arc buf is compressed, we need to decompress it to 1172 * read the data. This could happen during the "zfs receive" of 1173 * a stream which is compressed and deduplicated. 1174 */ 1175 if (db->db_buf != NULL && 1176 arc_get_compression(db->db_buf) != ZIO_COMPRESS_OFF) { 1177 dbuf_fix_old_data(db, 1178 spa_syncing_txg(dmu_objset_spa(db->db_objset))); 1179 err = arc_decompress(db->db_buf); 1180 dbuf_set_data(db, db->db_buf); 1181 } 1182 mutex_exit(&db->db_mtx); 1183 if (prefetch) 1184 dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1, B_TRUE); 1185 if ((flags & DB_RF_HAVESTRUCT) == 0) 1186 rw_exit(&dn->dn_struct_rwlock); 1187 DB_DNODE_EXIT(db); 1188 } else if (db->db_state == DB_UNCACHED) { 1189 spa_t *spa = dn->dn_objset->os_spa; 1190 boolean_t need_wait = B_FALSE; 1191 1192 if (zio == NULL && 1193 db->db_blkptr != NULL && !BP_IS_HOLE(db->db_blkptr)) { 1194 zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL); 1195 need_wait = B_TRUE; 1196 } 1197 dbuf_read_impl(db, zio, flags); 1198 1199 /* dbuf_read_impl has dropped db_mtx for us */ 1200 1201 if (prefetch) 1202 dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1, B_TRUE); 1203 1204 if ((flags & DB_RF_HAVESTRUCT) == 0) 1205 rw_exit(&dn->dn_struct_rwlock); 1206 DB_DNODE_EXIT(db); 1207 1208 if (need_wait) 1209 err = zio_wait(zio); 1210 } else { 1211 /* 1212 * Another reader came in while the dbuf was in flight 1213 * between UNCACHED and CACHED. Either a writer will finish 1214 * writing the buffer (sending the dbuf to CACHED) or the 1215 * first reader's request will reach the read_done callback 1216 * and send the dbuf to CACHED. Otherwise, a failure 1217 * occurred and the dbuf went to UNCACHED. 1218 */ 1219 mutex_exit(&db->db_mtx); 1220 if (prefetch) 1221 dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1, B_TRUE); 1222 if ((flags & DB_RF_HAVESTRUCT) == 0) 1223 rw_exit(&dn->dn_struct_rwlock); 1224 DB_DNODE_EXIT(db); 1225 1226 /* Skip the wait per the caller's request. */ 1227 mutex_enter(&db->db_mtx); 1228 if ((flags & DB_RF_NEVERWAIT) == 0) { 1229 while (db->db_state == DB_READ || 1230 db->db_state == DB_FILL) { 1231 ASSERT(db->db_state == DB_READ || 1232 (flags & DB_RF_HAVESTRUCT) == 0); 1233 DTRACE_PROBE2(blocked__read, dmu_buf_impl_t *, 1234 db, zio_t *, zio); 1235 cv_wait(&db->db_changed, &db->db_mtx); 1236 } 1237 if (db->db_state == DB_UNCACHED) 1238 err = SET_ERROR(EIO); 1239 } 1240 mutex_exit(&db->db_mtx); 1241 } 1242 1243 return (err); 1244 } 1245 1246 static void 1247 dbuf_noread(dmu_buf_impl_t *db) 1248 { 1249 ASSERT(!zfs_refcount_is_zero(&db->db_holds)); 1250 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1251 mutex_enter(&db->db_mtx); 1252 while (db->db_state == DB_READ || db->db_state == DB_FILL) 1253 cv_wait(&db->db_changed, &db->db_mtx); 1254 if (db->db_state == DB_UNCACHED) { 1255 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 1256 spa_t *spa = db->db_objset->os_spa; 1257 1258 ASSERT(db->db_buf == NULL); 1259 ASSERT(db->db.db_data == NULL); 1260 dbuf_set_data(db, arc_alloc_buf(spa, db, type, db->db.db_size)); 1261 db->db_state = DB_FILL; 1262 } else if (db->db_state == DB_NOFILL) { 1263 dbuf_clear_data(db); 1264 } else { 1265 ASSERT3U(db->db_state, ==, DB_CACHED); 1266 } 1267 mutex_exit(&db->db_mtx); 1268 } 1269 1270 void 1271 dbuf_unoverride(dbuf_dirty_record_t *dr) 1272 { 1273 dmu_buf_impl_t *db = dr->dr_dbuf; 1274 blkptr_t *bp = &dr->dt.dl.dr_overridden_by; 1275 uint64_t txg = dr->dr_txg; 1276 1277 ASSERT(MUTEX_HELD(&db->db_mtx)); 1278 /* 1279 * This assert is valid because dmu_sync() expects to be called by 1280 * a zilog's get_data while holding a range lock. This call only 1281 * comes from dbuf_dirty() callers who must also hold a range lock. 1282 */ 1283 ASSERT(dr->dt.dl.dr_override_state != DR_IN_DMU_SYNC); 1284 ASSERT(db->db_level == 0); 1285 1286 if (db->db_blkid == DMU_BONUS_BLKID || 1287 dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN) 1288 return; 1289 1290 ASSERT(db->db_data_pending != dr); 1291 1292 /* free this block */ 1293 if (!BP_IS_HOLE(bp) && !dr->dt.dl.dr_nopwrite) 1294 zio_free(db->db_objset->os_spa, txg, bp); 1295 1296 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN; 1297 dr->dt.dl.dr_nopwrite = B_FALSE; 1298 1299 /* 1300 * Release the already-written buffer, so we leave it in 1301 * a consistent dirty state. Note that all callers are 1302 * modifying the buffer, so they will immediately do 1303 * another (redundant) arc_release(). Therefore, leave 1304 * the buf thawed to save the effort of freezing & 1305 * immediately re-thawing it. 1306 */ 1307 arc_release(dr->dt.dl.dr_data, db); 1308 } 1309 1310 /* 1311 * Evict (if its unreferenced) or clear (if its referenced) any level-0 1312 * data blocks in the free range, so that any future readers will find 1313 * empty blocks. 1314 */ 1315 void 1316 dbuf_free_range(dnode_t *dn, uint64_t start_blkid, uint64_t end_blkid, 1317 dmu_tx_t *tx) 1318 { 1319 dmu_buf_impl_t db_search; 1320 dmu_buf_impl_t *db, *db_next; 1321 uint64_t txg = tx->tx_txg; 1322 avl_index_t where; 1323 1324 if (end_blkid > dn->dn_maxblkid && 1325 !(start_blkid == DMU_SPILL_BLKID || end_blkid == DMU_SPILL_BLKID)) 1326 end_blkid = dn->dn_maxblkid; 1327 dprintf_dnode(dn, "start=%llu end=%llu\n", start_blkid, end_blkid); 1328 1329 db_search.db_level = 0; 1330 db_search.db_blkid = start_blkid; 1331 db_search.db_state = DB_SEARCH; 1332 1333 mutex_enter(&dn->dn_dbufs_mtx); 1334 db = avl_find(&dn->dn_dbufs, &db_search, &where); 1335 ASSERT3P(db, ==, NULL); 1336 1337 db = avl_nearest(&dn->dn_dbufs, where, AVL_AFTER); 1338 1339 for (; db != NULL; db = db_next) { 1340 db_next = AVL_NEXT(&dn->dn_dbufs, db); 1341 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1342 1343 if (db->db_level != 0 || db->db_blkid > end_blkid) { 1344 break; 1345 } 1346 ASSERT3U(db->db_blkid, >=, start_blkid); 1347 1348 /* found a level 0 buffer in the range */ 1349 mutex_enter(&db->db_mtx); 1350 if (dbuf_undirty(db, tx)) { 1351 /* mutex has been dropped and dbuf destroyed */ 1352 continue; 1353 } 1354 1355 if (db->db_state == DB_UNCACHED || 1356 db->db_state == DB_NOFILL || 1357 db->db_state == DB_EVICTING) { 1358 ASSERT(db->db.db_data == NULL); 1359 mutex_exit(&db->db_mtx); 1360 continue; 1361 } 1362 if (db->db_state == DB_READ || db->db_state == DB_FILL) { 1363 /* will be handled in dbuf_read_done or dbuf_rele */ 1364 db->db_freed_in_flight = TRUE; 1365 mutex_exit(&db->db_mtx); 1366 continue; 1367 } 1368 if (zfs_refcount_count(&db->db_holds) == 0) { 1369 ASSERT(db->db_buf); 1370 dbuf_destroy(db); 1371 continue; 1372 } 1373 /* The dbuf is referenced */ 1374 1375 if (db->db_last_dirty != NULL) { 1376 dbuf_dirty_record_t *dr = db->db_last_dirty; 1377 1378 if (dr->dr_txg == txg) { 1379 /* 1380 * This buffer is "in-use", re-adjust the file 1381 * size to reflect that this buffer may 1382 * contain new data when we sync. 1383 */ 1384 if (db->db_blkid != DMU_SPILL_BLKID && 1385 db->db_blkid > dn->dn_maxblkid) 1386 dn->dn_maxblkid = db->db_blkid; 1387 dbuf_unoverride(dr); 1388 } else { 1389 /* 1390 * This dbuf is not dirty in the open context. 1391 * Either uncache it (if its not referenced in 1392 * the open context) or reset its contents to 1393 * empty. 1394 */ 1395 dbuf_fix_old_data(db, txg); 1396 } 1397 } 1398 /* clear the contents if its cached */ 1399 if (db->db_state == DB_CACHED) { 1400 ASSERT(db->db.db_data != NULL); 1401 arc_release(db->db_buf, db); 1402 bzero(db->db.db_data, db->db.db_size); 1403 arc_buf_freeze(db->db_buf); 1404 } 1405 1406 mutex_exit(&db->db_mtx); 1407 } 1408 mutex_exit(&dn->dn_dbufs_mtx); 1409 } 1410 1411 void 1412 dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx) 1413 { 1414 arc_buf_t *buf, *obuf; 1415 int osize = db->db.db_size; 1416 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 1417 dnode_t *dn; 1418 1419 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1420 1421 DB_DNODE_ENTER(db); 1422 dn = DB_DNODE(db); 1423 1424 /* XXX does *this* func really need the lock? */ 1425 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock)); 1426 1427 /* 1428 * This call to dmu_buf_will_dirty() with the dn_struct_rwlock held 1429 * is OK, because there can be no other references to the db 1430 * when we are changing its size, so no concurrent DB_FILL can 1431 * be happening. 1432 */ 1433 /* 1434 * XXX we should be doing a dbuf_read, checking the return 1435 * value and returning that up to our callers 1436 */ 1437 dmu_buf_will_dirty(&db->db, tx); 1438 1439 /* create the data buffer for the new block */ 1440 buf = arc_alloc_buf(dn->dn_objset->os_spa, db, type, size); 1441 1442 /* copy old block data to the new block */ 1443 obuf = db->db_buf; 1444 bcopy(obuf->b_data, buf->b_data, MIN(osize, size)); 1445 /* zero the remainder */ 1446 if (size > osize) 1447 bzero((uint8_t *)buf->b_data + osize, size - osize); 1448 1449 mutex_enter(&db->db_mtx); 1450 dbuf_set_data(db, buf); 1451 arc_buf_destroy(obuf, db); 1452 db->db.db_size = size; 1453 1454 if (db->db_level == 0) { 1455 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg); 1456 db->db_last_dirty->dt.dl.dr_data = buf; 1457 } 1458 mutex_exit(&db->db_mtx); 1459 1460 dmu_objset_willuse_space(dn->dn_objset, size - osize, tx); 1461 DB_DNODE_EXIT(db); 1462 } 1463 1464 void 1465 dbuf_release_bp(dmu_buf_impl_t *db) 1466 { 1467 objset_t *os = db->db_objset; 1468 1469 ASSERT(dsl_pool_sync_context(dmu_objset_pool(os))); 1470 ASSERT(arc_released(os->os_phys_buf) || 1471 list_link_active(&os->os_dsl_dataset->ds_synced_link)); 1472 ASSERT(db->db_parent == NULL || arc_released(db->db_parent->db_buf)); 1473 1474 (void) arc_release(db->db_buf, db); 1475 } 1476 1477 /* 1478 * We already have a dirty record for this TXG, and we are being 1479 * dirtied again. 1480 */ 1481 static void 1482 dbuf_redirty(dbuf_dirty_record_t *dr) 1483 { 1484 dmu_buf_impl_t *db = dr->dr_dbuf; 1485 1486 ASSERT(MUTEX_HELD(&db->db_mtx)); 1487 1488 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID) { 1489 /* 1490 * If this buffer has already been written out, 1491 * we now need to reset its state. 1492 */ 1493 dbuf_unoverride(dr); 1494 if (db->db.db_object != DMU_META_DNODE_OBJECT && 1495 db->db_state != DB_NOFILL) { 1496 /* Already released on initial dirty, so just thaw. */ 1497 ASSERT(arc_released(db->db_buf)); 1498 arc_buf_thaw(db->db_buf); 1499 } 1500 } 1501 } 1502 1503 dbuf_dirty_record_t * 1504 dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx) 1505 { 1506 dnode_t *dn; 1507 objset_t *os; 1508 dbuf_dirty_record_t **drp, *dr; 1509 int drop_struct_lock = FALSE; 1510 int txgoff = tx->tx_txg & TXG_MASK; 1511 1512 ASSERT(tx->tx_txg != 0); 1513 ASSERT(!zfs_refcount_is_zero(&db->db_holds)); 1514 DMU_TX_DIRTY_BUF(tx, db); 1515 1516 DB_DNODE_ENTER(db); 1517 dn = DB_DNODE(db); 1518 /* 1519 * Shouldn't dirty a regular buffer in syncing context. Private 1520 * objects may be dirtied in syncing context, but only if they 1521 * were already pre-dirtied in open context. 1522 */ 1523 #ifdef DEBUG 1524 if (dn->dn_objset->os_dsl_dataset != NULL) { 1525 rrw_enter(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock, 1526 RW_READER, FTAG); 1527 } 1528 ASSERT(!dmu_tx_is_syncing(tx) || 1529 BP_IS_HOLE(dn->dn_objset->os_rootbp) || 1530 DMU_OBJECT_IS_SPECIAL(dn->dn_object) || 1531 dn->dn_objset->os_dsl_dataset == NULL); 1532 if (dn->dn_objset->os_dsl_dataset != NULL) 1533 rrw_exit(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock, FTAG); 1534 #endif 1535 /* 1536 * We make this assert for private objects as well, but after we 1537 * check if we're already dirty. They are allowed to re-dirty 1538 * in syncing context. 1539 */ 1540 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT || 1541 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx == 1542 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN)); 1543 1544 mutex_enter(&db->db_mtx); 1545 /* 1546 * XXX make this true for indirects too? The problem is that 1547 * transactions created with dmu_tx_create_assigned() from 1548 * syncing context don't bother holding ahead. 1549 */ 1550 ASSERT(db->db_level != 0 || 1551 db->db_state == DB_CACHED || db->db_state == DB_FILL || 1552 db->db_state == DB_NOFILL); 1553 1554 mutex_enter(&dn->dn_mtx); 1555 /* 1556 * Don't set dirtyctx to SYNC if we're just modifying this as we 1557 * initialize the objset. 1558 */ 1559 if (dn->dn_dirtyctx == DN_UNDIRTIED) { 1560 if (dn->dn_objset->os_dsl_dataset != NULL) { 1561 rrw_enter(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock, 1562 RW_READER, FTAG); 1563 } 1564 if (!BP_IS_HOLE(dn->dn_objset->os_rootbp)) { 1565 dn->dn_dirtyctx = (dmu_tx_is_syncing(tx) ? 1566 DN_DIRTY_SYNC : DN_DIRTY_OPEN); 1567 ASSERT(dn->dn_dirtyctx_firstset == NULL); 1568 dn->dn_dirtyctx_firstset = kmem_alloc(1, KM_SLEEP); 1569 } 1570 if (dn->dn_objset->os_dsl_dataset != NULL) { 1571 rrw_exit(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock, 1572 FTAG); 1573 } 1574 } 1575 mutex_exit(&dn->dn_mtx); 1576 1577 if (db->db_blkid == DMU_SPILL_BLKID) 1578 dn->dn_have_spill = B_TRUE; 1579 1580 /* 1581 * If this buffer is already dirty, we're done. 1582 */ 1583 drp = &db->db_last_dirty; 1584 ASSERT(*drp == NULL || (*drp)->dr_txg <= tx->tx_txg || 1585 db->db.db_object == DMU_META_DNODE_OBJECT); 1586 while ((dr = *drp) != NULL && dr->dr_txg > tx->tx_txg) 1587 drp = &dr->dr_next; 1588 if (dr && dr->dr_txg == tx->tx_txg) { 1589 DB_DNODE_EXIT(db); 1590 1591 dbuf_redirty(dr); 1592 mutex_exit(&db->db_mtx); 1593 return (dr); 1594 } 1595 1596 /* 1597 * Only valid if not already dirty. 1598 */ 1599 ASSERT(dn->dn_object == 0 || 1600 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx == 1601 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN)); 1602 1603 ASSERT3U(dn->dn_nlevels, >, db->db_level); 1604 1605 /* 1606 * We should only be dirtying in syncing context if it's the 1607 * mos or we're initializing the os or it's a special object. 1608 * However, we are allowed to dirty in syncing context provided 1609 * we already dirtied it in open context. Hence we must make 1610 * this assertion only if we're not already dirty. 1611 */ 1612 os = dn->dn_objset; 1613 VERIFY3U(tx->tx_txg, <=, spa_final_dirty_txg(os->os_spa)); 1614 #ifdef DEBUG 1615 if (dn->dn_objset->os_dsl_dataset != NULL) 1616 rrw_enter(&os->os_dsl_dataset->ds_bp_rwlock, RW_READER, FTAG); 1617 ASSERT(!dmu_tx_is_syncing(tx) || DMU_OBJECT_IS_SPECIAL(dn->dn_object) || 1618 os->os_dsl_dataset == NULL || BP_IS_HOLE(os->os_rootbp)); 1619 if (dn->dn_objset->os_dsl_dataset != NULL) 1620 rrw_exit(&os->os_dsl_dataset->ds_bp_rwlock, FTAG); 1621 #endif 1622 ASSERT(db->db.db_size != 0); 1623 1624 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size); 1625 1626 if (db->db_blkid != DMU_BONUS_BLKID) { 1627 dmu_objset_willuse_space(os, db->db.db_size, tx); 1628 } 1629 1630 /* 1631 * If this buffer is dirty in an old transaction group we need 1632 * to make a copy of it so that the changes we make in this 1633 * transaction group won't leak out when we sync the older txg. 1634 */ 1635 dr = kmem_zalloc(sizeof (dbuf_dirty_record_t), KM_SLEEP); 1636 if (db->db_level == 0) { 1637 void *data_old = db->db_buf; 1638 1639 if (db->db_state != DB_NOFILL) { 1640 if (db->db_blkid == DMU_BONUS_BLKID) { 1641 dbuf_fix_old_data(db, tx->tx_txg); 1642 data_old = db->db.db_data; 1643 } else if (db->db.db_object != DMU_META_DNODE_OBJECT) { 1644 /* 1645 * Release the data buffer from the cache so 1646 * that we can modify it without impacting 1647 * possible other users of this cached data 1648 * block. Note that indirect blocks and 1649 * private objects are not released until the 1650 * syncing state (since they are only modified 1651 * then). 1652 */ 1653 arc_release(db->db_buf, db); 1654 dbuf_fix_old_data(db, tx->tx_txg); 1655 data_old = db->db_buf; 1656 } 1657 ASSERT(data_old != NULL); 1658 } 1659 dr->dt.dl.dr_data = data_old; 1660 } else { 1661 mutex_init(&dr->dt.di.dr_mtx, NULL, MUTEX_DEFAULT, NULL); 1662 list_create(&dr->dt.di.dr_children, 1663 sizeof (dbuf_dirty_record_t), 1664 offsetof(dbuf_dirty_record_t, dr_dirty_node)); 1665 } 1666 if (db->db_blkid != DMU_BONUS_BLKID && os->os_dsl_dataset != NULL) 1667 dr->dr_accounted = db->db.db_size; 1668 dr->dr_dbuf = db; 1669 dr->dr_txg = tx->tx_txg; 1670 dr->dr_next = *drp; 1671 *drp = dr; 1672 1673 /* 1674 * We could have been freed_in_flight between the dbuf_noread 1675 * and dbuf_dirty. We win, as though the dbuf_noread() had 1676 * happened after the free. 1677 */ 1678 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID && 1679 db->db_blkid != DMU_SPILL_BLKID) { 1680 mutex_enter(&dn->dn_mtx); 1681 if (dn->dn_free_ranges[txgoff] != NULL) { 1682 range_tree_clear(dn->dn_free_ranges[txgoff], 1683 db->db_blkid, 1); 1684 } 1685 mutex_exit(&dn->dn_mtx); 1686 db->db_freed_in_flight = FALSE; 1687 } 1688 1689 /* 1690 * This buffer is now part of this txg 1691 */ 1692 dbuf_add_ref(db, (void *)(uintptr_t)tx->tx_txg); 1693 db->db_dirtycnt += 1; 1694 ASSERT3U(db->db_dirtycnt, <=, 3); 1695 1696 mutex_exit(&db->db_mtx); 1697 1698 if (db->db_blkid == DMU_BONUS_BLKID || 1699 db->db_blkid == DMU_SPILL_BLKID) { 1700 mutex_enter(&dn->dn_mtx); 1701 ASSERT(!list_link_active(&dr->dr_dirty_node)); 1702 list_insert_tail(&dn->dn_dirty_records[txgoff], dr); 1703 mutex_exit(&dn->dn_mtx); 1704 dnode_setdirty(dn, tx); 1705 DB_DNODE_EXIT(db); 1706 return (dr); 1707 } 1708 1709 /* 1710 * The dn_struct_rwlock prevents db_blkptr from changing 1711 * due to a write from syncing context completing 1712 * while we are running, so we want to acquire it before 1713 * looking at db_blkptr. 1714 */ 1715 if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) { 1716 rw_enter(&dn->dn_struct_rwlock, RW_READER); 1717 drop_struct_lock = TRUE; 1718 } 1719 1720 /* 1721 * We need to hold the dn_struct_rwlock to make this assertion, 1722 * because it protects dn_phys / dn_next_nlevels from changing. 1723 */ 1724 ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) || 1725 dn->dn_phys->dn_nlevels > db->db_level || 1726 dn->dn_next_nlevels[txgoff] > db->db_level || 1727 dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level || 1728 dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level); 1729 1730 /* 1731 * If we are overwriting a dedup BP, then unless it is snapshotted, 1732 * when we get to syncing context we will need to decrement its 1733 * refcount in the DDT. Prefetch the relevant DDT block so that 1734 * syncing context won't have to wait for the i/o. 1735 */ 1736 ddt_prefetch(os->os_spa, db->db_blkptr); 1737 1738 if (db->db_level == 0) { 1739 dnode_new_blkid(dn, db->db_blkid, tx, drop_struct_lock); 1740 ASSERT(dn->dn_maxblkid >= db->db_blkid); 1741 } 1742 1743 if (db->db_level+1 < dn->dn_nlevels) { 1744 dmu_buf_impl_t *parent = db->db_parent; 1745 dbuf_dirty_record_t *di; 1746 int parent_held = FALSE; 1747 1748 if (db->db_parent == NULL || db->db_parent == dn->dn_dbuf) { 1749 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT; 1750 1751 parent = dbuf_hold_level(dn, db->db_level+1, 1752 db->db_blkid >> epbs, FTAG); 1753 ASSERT(parent != NULL); 1754 parent_held = TRUE; 1755 } 1756 if (drop_struct_lock) 1757 rw_exit(&dn->dn_struct_rwlock); 1758 ASSERT3U(db->db_level+1, ==, parent->db_level); 1759 di = dbuf_dirty(parent, tx); 1760 if (parent_held) 1761 dbuf_rele(parent, FTAG); 1762 1763 mutex_enter(&db->db_mtx); 1764 /* 1765 * Since we've dropped the mutex, it's possible that 1766 * dbuf_undirty() might have changed this out from under us. 1767 */ 1768 if (db->db_last_dirty == dr || 1769 dn->dn_object == DMU_META_DNODE_OBJECT) { 1770 mutex_enter(&di->dt.di.dr_mtx); 1771 ASSERT3U(di->dr_txg, ==, tx->tx_txg); 1772 ASSERT(!list_link_active(&dr->dr_dirty_node)); 1773 list_insert_tail(&di->dt.di.dr_children, dr); 1774 mutex_exit(&di->dt.di.dr_mtx); 1775 dr->dr_parent = di; 1776 } 1777 mutex_exit(&db->db_mtx); 1778 } else { 1779 ASSERT(db->db_level+1 == dn->dn_nlevels); 1780 ASSERT(db->db_blkid < dn->dn_nblkptr); 1781 ASSERT(db->db_parent == NULL || db->db_parent == dn->dn_dbuf); 1782 mutex_enter(&dn->dn_mtx); 1783 ASSERT(!list_link_active(&dr->dr_dirty_node)); 1784 list_insert_tail(&dn->dn_dirty_records[txgoff], dr); 1785 mutex_exit(&dn->dn_mtx); 1786 if (drop_struct_lock) 1787 rw_exit(&dn->dn_struct_rwlock); 1788 } 1789 1790 dnode_setdirty(dn, tx); 1791 DB_DNODE_EXIT(db); 1792 return (dr); 1793 } 1794 1795 /* 1796 * Undirty a buffer in the transaction group referenced by the given 1797 * transaction. Return whether this evicted the dbuf. 1798 */ 1799 static boolean_t 1800 dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx) 1801 { 1802 dnode_t *dn; 1803 uint64_t txg = tx->tx_txg; 1804 dbuf_dirty_record_t *dr, **drp; 1805 1806 ASSERT(txg != 0); 1807 1808 /* 1809 * Due to our use of dn_nlevels below, this can only be called 1810 * in open context, unless we are operating on the MOS. 1811 * From syncing context, dn_nlevels may be different from the 1812 * dn_nlevels used when dbuf was dirtied. 1813 */ 1814 ASSERT(db->db_objset == 1815 dmu_objset_pool(db->db_objset)->dp_meta_objset || 1816 txg != spa_syncing_txg(dmu_objset_spa(db->db_objset))); 1817 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1818 ASSERT0(db->db_level); 1819 ASSERT(MUTEX_HELD(&db->db_mtx)); 1820 1821 /* 1822 * If this buffer is not dirty, we're done. 1823 */ 1824 for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next) 1825 if (dr->dr_txg <= txg) 1826 break; 1827 if (dr == NULL || dr->dr_txg < txg) 1828 return (B_FALSE); 1829 ASSERT(dr->dr_txg == txg); 1830 ASSERT(dr->dr_dbuf == db); 1831 1832 DB_DNODE_ENTER(db); 1833 dn = DB_DNODE(db); 1834 1835 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size); 1836 1837 ASSERT(db->db.db_size != 0); 1838 1839 dsl_pool_undirty_space(dmu_objset_pool(dn->dn_objset), 1840 dr->dr_accounted, txg); 1841 1842 *drp = dr->dr_next; 1843 1844 /* 1845 * Note that there are three places in dbuf_dirty() 1846 * where this dirty record may be put on a list. 1847 * Make sure to do a list_remove corresponding to 1848 * every one of those list_insert calls. 1849 */ 1850 if (dr->dr_parent) { 1851 mutex_enter(&dr->dr_parent->dt.di.dr_mtx); 1852 list_remove(&dr->dr_parent->dt.di.dr_children, dr); 1853 mutex_exit(&dr->dr_parent->dt.di.dr_mtx); 1854 } else if (db->db_blkid == DMU_SPILL_BLKID || 1855 db->db_level + 1 == dn->dn_nlevels) { 1856 ASSERT(db->db_blkptr == NULL || db->db_parent == dn->dn_dbuf); 1857 mutex_enter(&dn->dn_mtx); 1858 list_remove(&dn->dn_dirty_records[txg & TXG_MASK], dr); 1859 mutex_exit(&dn->dn_mtx); 1860 } 1861 DB_DNODE_EXIT(db); 1862 1863 if (db->db_state != DB_NOFILL) { 1864 dbuf_unoverride(dr); 1865 1866 ASSERT(db->db_buf != NULL); 1867 ASSERT(dr->dt.dl.dr_data != NULL); 1868 if (dr->dt.dl.dr_data != db->db_buf) 1869 arc_buf_destroy(dr->dt.dl.dr_data, db); 1870 } 1871 1872 kmem_free(dr, sizeof (dbuf_dirty_record_t)); 1873 1874 ASSERT(db->db_dirtycnt > 0); 1875 db->db_dirtycnt -= 1; 1876 1877 if (zfs_refcount_remove(&db->db_holds, (void *)(uintptr_t)txg) == 0) { 1878 ASSERT(db->db_state == DB_NOFILL || arc_released(db->db_buf)); 1879 dbuf_destroy(db); 1880 return (B_TRUE); 1881 } 1882 1883 return (B_FALSE); 1884 } 1885 1886 void 1887 dmu_buf_will_dirty(dmu_buf_t *db_fake, dmu_tx_t *tx) 1888 { 1889 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 1890 int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH; 1891 1892 ASSERT(tx->tx_txg != 0); 1893 ASSERT(!zfs_refcount_is_zero(&db->db_holds)); 1894 1895 /* 1896 * Quick check for dirtyness. For already dirty blocks, this 1897 * reduces runtime of this function by >90%, and overall performance 1898 * by 50% for some workloads (e.g. file deletion with indirect blocks 1899 * cached). 1900 */ 1901 mutex_enter(&db->db_mtx); 1902 dbuf_dirty_record_t *dr; 1903 for (dr = db->db_last_dirty; 1904 dr != NULL && dr->dr_txg >= tx->tx_txg; dr = dr->dr_next) { 1905 /* 1906 * It's possible that it is already dirty but not cached, 1907 * because there are some calls to dbuf_dirty() that don't 1908 * go through dmu_buf_will_dirty(). 1909 */ 1910 if (dr->dr_txg == tx->tx_txg && db->db_state == DB_CACHED) { 1911 /* This dbuf is already dirty and cached. */ 1912 dbuf_redirty(dr); 1913 mutex_exit(&db->db_mtx); 1914 return; 1915 } 1916 } 1917 mutex_exit(&db->db_mtx); 1918 1919 DB_DNODE_ENTER(db); 1920 if (RW_WRITE_HELD(&DB_DNODE(db)->dn_struct_rwlock)) 1921 rf |= DB_RF_HAVESTRUCT; 1922 DB_DNODE_EXIT(db); 1923 (void) dbuf_read(db, NULL, rf); 1924 (void) dbuf_dirty(db, tx); 1925 } 1926 1927 void 1928 dmu_buf_will_not_fill(dmu_buf_t *db_fake, dmu_tx_t *tx) 1929 { 1930 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 1931 1932 db->db_state = DB_NOFILL; 1933 1934 dmu_buf_will_fill(db_fake, tx); 1935 } 1936 1937 void 1938 dmu_buf_will_fill(dmu_buf_t *db_fake, dmu_tx_t *tx) 1939 { 1940 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 1941 1942 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1943 ASSERT(tx->tx_txg != 0); 1944 ASSERT(db->db_level == 0); 1945 ASSERT(!zfs_refcount_is_zero(&db->db_holds)); 1946 1947 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT || 1948 dmu_tx_private_ok(tx)); 1949 1950 dbuf_noread(db); 1951 (void) dbuf_dirty(db, tx); 1952 } 1953 1954 #pragma weak dmu_buf_fill_done = dbuf_fill_done 1955 /* ARGSUSED */ 1956 void 1957 dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx) 1958 { 1959 mutex_enter(&db->db_mtx); 1960 DBUF_VERIFY(db); 1961 1962 if (db->db_state == DB_FILL) { 1963 if (db->db_level == 0 && db->db_freed_in_flight) { 1964 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1965 /* we were freed while filling */ 1966 /* XXX dbuf_undirty? */ 1967 bzero(db->db.db_data, db->db.db_size); 1968 db->db_freed_in_flight = FALSE; 1969 } 1970 db->db_state = DB_CACHED; 1971 cv_broadcast(&db->db_changed); 1972 } 1973 mutex_exit(&db->db_mtx); 1974 } 1975 1976 void 1977 dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data, 1978 bp_embedded_type_t etype, enum zio_compress comp, 1979 int uncompressed_size, int compressed_size, int byteorder, 1980 dmu_tx_t *tx) 1981 { 1982 dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf; 1983 struct dirty_leaf *dl; 1984 dmu_object_type_t type; 1985 1986 if (etype == BP_EMBEDDED_TYPE_DATA) { 1987 ASSERT(spa_feature_is_active(dmu_objset_spa(db->db_objset), 1988 SPA_FEATURE_EMBEDDED_DATA)); 1989 } 1990 1991 DB_DNODE_ENTER(db); 1992 type = DB_DNODE(db)->dn_type; 1993 DB_DNODE_EXIT(db); 1994 1995 ASSERT0(db->db_level); 1996 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1997 1998 dmu_buf_will_not_fill(dbuf, tx); 1999 2000 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg); 2001 dl = &db->db_last_dirty->dt.dl; 2002 encode_embedded_bp_compressed(&dl->dr_overridden_by, 2003 data, comp, uncompressed_size, compressed_size); 2004 BPE_SET_ETYPE(&dl->dr_overridden_by, etype); 2005 BP_SET_TYPE(&dl->dr_overridden_by, type); 2006 BP_SET_LEVEL(&dl->dr_overridden_by, 0); 2007 BP_SET_BYTEORDER(&dl->dr_overridden_by, byteorder); 2008 2009 dl->dr_override_state = DR_OVERRIDDEN; 2010 dl->dr_overridden_by.blk_birth = db->db_last_dirty->dr_txg; 2011 } 2012 2013 /* 2014 * Directly assign a provided arc buf to a given dbuf if it's not referenced 2015 * by anybody except our caller. Otherwise copy arcbuf's contents to dbuf. 2016 */ 2017 void 2018 dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx) 2019 { 2020 ASSERT(!zfs_refcount_is_zero(&db->db_holds)); 2021 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 2022 ASSERT(db->db_level == 0); 2023 ASSERT3U(dbuf_is_metadata(db), ==, arc_is_metadata(buf)); 2024 ASSERT(buf != NULL); 2025 ASSERT(arc_buf_lsize(buf) == db->db.db_size); 2026 ASSERT(tx->tx_txg != 0); 2027 2028 arc_return_buf(buf, db); 2029 ASSERT(arc_released(buf)); 2030 2031 mutex_enter(&db->db_mtx); 2032 2033 while (db->db_state == DB_READ || db->db_state == DB_FILL) 2034 cv_wait(&db->db_changed, &db->db_mtx); 2035 2036 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED); 2037 2038 if (db->db_state == DB_CACHED && 2039 zfs_refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) { 2040 mutex_exit(&db->db_mtx); 2041 (void) dbuf_dirty(db, tx); 2042 bcopy(buf->b_data, db->db.db_data, db->db.db_size); 2043 arc_buf_destroy(buf, db); 2044 xuio_stat_wbuf_copied(); 2045 return; 2046 } 2047 2048 xuio_stat_wbuf_nocopy(); 2049 if (db->db_state == DB_CACHED) { 2050 dbuf_dirty_record_t *dr = db->db_last_dirty; 2051 2052 ASSERT(db->db_buf != NULL); 2053 if (dr != NULL && dr->dr_txg == tx->tx_txg) { 2054 ASSERT(dr->dt.dl.dr_data == db->db_buf); 2055 if (!arc_released(db->db_buf)) { 2056 ASSERT(dr->dt.dl.dr_override_state == 2057 DR_OVERRIDDEN); 2058 arc_release(db->db_buf, db); 2059 } 2060 dr->dt.dl.dr_data = buf; 2061 arc_buf_destroy(db->db_buf, db); 2062 } else if (dr == NULL || dr->dt.dl.dr_data != db->db_buf) { 2063 arc_release(db->db_buf, db); 2064 arc_buf_destroy(db->db_buf, db); 2065 } 2066 db->db_buf = NULL; 2067 } 2068 ASSERT(db->db_buf == NULL); 2069 dbuf_set_data(db, buf); 2070 db->db_state = DB_FILL; 2071 mutex_exit(&db->db_mtx); 2072 (void) dbuf_dirty(db, tx); 2073 dmu_buf_fill_done(&db->db, tx); 2074 } 2075 2076 void 2077 dbuf_destroy(dmu_buf_impl_t *db) 2078 { 2079 dnode_t *dn; 2080 dmu_buf_impl_t *parent = db->db_parent; 2081 dmu_buf_impl_t *dndb; 2082 2083 ASSERT(MUTEX_HELD(&db->db_mtx)); 2084 ASSERT(zfs_refcount_is_zero(&db->db_holds)); 2085 2086 if (db->db_buf != NULL) { 2087 arc_buf_destroy(db->db_buf, db); 2088 db->db_buf = NULL; 2089 } 2090 2091 if (db->db_blkid == DMU_BONUS_BLKID) { 2092 int slots = DB_DNODE(db)->dn_num_slots; 2093 int bonuslen = DN_SLOTS_TO_BONUSLEN(slots); 2094 if (db->db.db_data != NULL) { 2095 zio_buf_free(db->db.db_data, bonuslen); 2096 arc_space_return(bonuslen, ARC_SPACE_BONUS); 2097 db->db_state = DB_UNCACHED; 2098 } 2099 } 2100 2101 dbuf_clear_data(db); 2102 2103 if (multilist_link_active(&db->db_cache_link)) { 2104 ASSERT(db->db_caching_status == DB_DBUF_CACHE || 2105 db->db_caching_status == DB_DBUF_METADATA_CACHE); 2106 2107 multilist_remove(dbuf_caches[db->db_caching_status].cache, db); 2108 (void) zfs_refcount_remove_many( 2109 &dbuf_caches[db->db_caching_status].size, 2110 db->db.db_size, db); 2111 2112 db->db_caching_status = DB_NO_CACHE; 2113 } 2114 2115 ASSERT(db->db_state == DB_UNCACHED || db->db_state == DB_NOFILL); 2116 ASSERT(db->db_data_pending == NULL); 2117 2118 db->db_state = DB_EVICTING; 2119 db->db_blkptr = NULL; 2120 2121 /* 2122 * Now that db_state is DB_EVICTING, nobody else can find this via 2123 * the hash table. We can now drop db_mtx, which allows us to 2124 * acquire the dn_dbufs_mtx. 2125 */ 2126 mutex_exit(&db->db_mtx); 2127 2128 DB_DNODE_ENTER(db); 2129 dn = DB_DNODE(db); 2130 dndb = dn->dn_dbuf; 2131 if (db->db_blkid != DMU_BONUS_BLKID) { 2132 boolean_t needlock = !MUTEX_HELD(&dn->dn_dbufs_mtx); 2133 if (needlock) 2134 mutex_enter(&dn->dn_dbufs_mtx); 2135 avl_remove(&dn->dn_dbufs, db); 2136 atomic_dec_32(&dn->dn_dbufs_count); 2137 membar_producer(); 2138 DB_DNODE_EXIT(db); 2139 if (needlock) 2140 mutex_exit(&dn->dn_dbufs_mtx); 2141 /* 2142 * Decrementing the dbuf count means that the hold corresponding 2143 * to the removed dbuf is no longer discounted in dnode_move(), 2144 * so the dnode cannot be moved until after we release the hold. 2145 * The membar_producer() ensures visibility of the decremented 2146 * value in dnode_move(), since DB_DNODE_EXIT doesn't actually 2147 * release any lock. 2148 */ 2149 mutex_enter(&dn->dn_mtx); 2150 dnode_rele_and_unlock(dn, db, B_TRUE); 2151 db->db_dnode_handle = NULL; 2152 2153 dbuf_hash_remove(db); 2154 } else { 2155 DB_DNODE_EXIT(db); 2156 } 2157 2158 ASSERT(zfs_refcount_is_zero(&db->db_holds)); 2159 2160 db->db_parent = NULL; 2161 2162 ASSERT(db->db_buf == NULL); 2163 ASSERT(db->db.db_data == NULL); 2164 ASSERT(db->db_hash_next == NULL); 2165 ASSERT(db->db_blkptr == NULL); 2166 ASSERT(db->db_data_pending == NULL); 2167 ASSERT3U(db->db_caching_status, ==, DB_NO_CACHE); 2168 ASSERT(!multilist_link_active(&db->db_cache_link)); 2169 2170 kmem_cache_free(dbuf_kmem_cache, db); 2171 arc_space_return(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER); 2172 2173 /* 2174 * If this dbuf is referenced from an indirect dbuf, 2175 * decrement the ref count on the indirect dbuf. 2176 */ 2177 if (parent && parent != dndb) { 2178 mutex_enter(&parent->db_mtx); 2179 dbuf_rele_and_unlock(parent, db, B_TRUE); 2180 } 2181 } 2182 2183 /* 2184 * Note: While bpp will always be updated if the function returns success, 2185 * parentp will not be updated if the dnode does not have dn_dbuf filled in; 2186 * this happens when the dnode is the meta-dnode, or a userused or groupused 2187 * object. 2188 */ 2189 static int 2190 dbuf_findbp(dnode_t *dn, int level, uint64_t blkid, int fail_sparse, 2191 dmu_buf_impl_t **parentp, blkptr_t **bpp) 2192 { 2193 *parentp = NULL; 2194 *bpp = NULL; 2195 2196 ASSERT(blkid != DMU_BONUS_BLKID); 2197 2198 if (blkid == DMU_SPILL_BLKID) { 2199 mutex_enter(&dn->dn_mtx); 2200 if (dn->dn_have_spill && 2201 (dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR)) 2202 *bpp = DN_SPILL_BLKPTR(dn->dn_phys); 2203 else 2204 *bpp = NULL; 2205 dbuf_add_ref(dn->dn_dbuf, NULL); 2206 *parentp = dn->dn_dbuf; 2207 mutex_exit(&dn->dn_mtx); 2208 return (0); 2209 } 2210 2211 int nlevels = 2212 (dn->dn_phys->dn_nlevels == 0) ? 1 : dn->dn_phys->dn_nlevels; 2213 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT; 2214 2215 ASSERT3U(level * epbs, <, 64); 2216 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 2217 /* 2218 * This assertion shouldn't trip as long as the max indirect block size 2219 * is less than 1M. The reason for this is that up to that point, 2220 * the number of levels required to address an entire object with blocks 2221 * of size SPA_MINBLOCKSIZE satisfies nlevels * epbs + 1 <= 64. In 2222 * other words, if N * epbs + 1 > 64, then if (N-1) * epbs + 1 > 55 2223 * (i.e. we can address the entire object), objects will all use at most 2224 * N-1 levels and the assertion won't overflow. However, once epbs is 2225 * 13, 4 * 13 + 1 = 53, but 5 * 13 + 1 = 66. Then, 4 levels will not be 2226 * enough to address an entire object, so objects will have 5 levels, 2227 * but then this assertion will overflow. 2228 * 2229 * All this is to say that if we ever increase DN_MAX_INDBLKSHIFT, we 2230 * need to redo this logic to handle overflows. 2231 */ 2232 ASSERT(level >= nlevels || 2233 ((nlevels - level - 1) * epbs) + 2234 highbit64(dn->dn_phys->dn_nblkptr) <= 64); 2235 if (level >= nlevels || 2236 blkid >= ((uint64_t)dn->dn_phys->dn_nblkptr << 2237 ((nlevels - level - 1) * epbs)) || 2238 (fail_sparse && 2239 blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))) { 2240 /* the buffer has no parent yet */ 2241 return (SET_ERROR(ENOENT)); 2242 } else if (level < nlevels-1) { 2243 /* this block is referenced from an indirect block */ 2244 int err = dbuf_hold_impl(dn, level+1, 2245 blkid >> epbs, fail_sparse, FALSE, NULL, parentp); 2246 if (err) 2247 return (err); 2248 err = dbuf_read(*parentp, NULL, 2249 (DB_RF_HAVESTRUCT | DB_RF_NOPREFETCH | DB_RF_CANFAIL)); 2250 if (err) { 2251 dbuf_rele(*parentp, NULL); 2252 *parentp = NULL; 2253 return (err); 2254 } 2255 *bpp = ((blkptr_t *)(*parentp)->db.db_data) + 2256 (blkid & ((1ULL << epbs) - 1)); 2257 if (blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs))) 2258 ASSERT(BP_IS_HOLE(*bpp)); 2259 return (0); 2260 } else { 2261 /* the block is referenced from the dnode */ 2262 ASSERT3U(level, ==, nlevels-1); 2263 ASSERT(dn->dn_phys->dn_nblkptr == 0 || 2264 blkid < dn->dn_phys->dn_nblkptr); 2265 if (dn->dn_dbuf) { 2266 dbuf_add_ref(dn->dn_dbuf, NULL); 2267 *parentp = dn->dn_dbuf; 2268 } 2269 *bpp = &dn->dn_phys->dn_blkptr[blkid]; 2270 return (0); 2271 } 2272 } 2273 2274 static dmu_buf_impl_t * 2275 dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid, 2276 dmu_buf_impl_t *parent, blkptr_t *blkptr) 2277 { 2278 objset_t *os = dn->dn_objset; 2279 dmu_buf_impl_t *db, *odb; 2280 2281 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 2282 ASSERT(dn->dn_type != DMU_OT_NONE); 2283 2284 db = kmem_cache_alloc(dbuf_kmem_cache, KM_SLEEP); 2285 2286 db->db_objset = os; 2287 db->db.db_object = dn->dn_object; 2288 db->db_level = level; 2289 db->db_blkid = blkid; 2290 db->db_last_dirty = NULL; 2291 db->db_dirtycnt = 0; 2292 db->db_dnode_handle = dn->dn_handle; 2293 db->db_parent = parent; 2294 db->db_blkptr = blkptr; 2295 2296 db->db_user = NULL; 2297 db->db_user_immediate_evict = FALSE; 2298 db->db_freed_in_flight = FALSE; 2299 db->db_pending_evict = FALSE; 2300 2301 if (blkid == DMU_BONUS_BLKID) { 2302 ASSERT3P(parent, ==, dn->dn_dbuf); 2303 db->db.db_size = DN_SLOTS_TO_BONUSLEN(dn->dn_num_slots) - 2304 (dn->dn_nblkptr-1) * sizeof (blkptr_t); 2305 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen); 2306 db->db.db_offset = DMU_BONUS_BLKID; 2307 db->db_state = DB_UNCACHED; 2308 db->db_caching_status = DB_NO_CACHE; 2309 /* the bonus dbuf is not placed in the hash table */ 2310 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER); 2311 return (db); 2312 } else if (blkid == DMU_SPILL_BLKID) { 2313 db->db.db_size = (blkptr != NULL) ? 2314 BP_GET_LSIZE(blkptr) : SPA_MINBLOCKSIZE; 2315 db->db.db_offset = 0; 2316 } else { 2317 int blocksize = 2318 db->db_level ? 1 << dn->dn_indblkshift : dn->dn_datablksz; 2319 db->db.db_size = blocksize; 2320 db->db.db_offset = db->db_blkid * blocksize; 2321 } 2322 2323 /* 2324 * Hold the dn_dbufs_mtx while we get the new dbuf 2325 * in the hash table *and* added to the dbufs list. 2326 * This prevents a possible deadlock with someone 2327 * trying to look up this dbuf before its added to the 2328 * dn_dbufs list. 2329 */ 2330 mutex_enter(&dn->dn_dbufs_mtx); 2331 db->db_state = DB_EVICTING; 2332 if ((odb = dbuf_hash_insert(db)) != NULL) { 2333 /* someone else inserted it first */ 2334 kmem_cache_free(dbuf_kmem_cache, db); 2335 mutex_exit(&dn->dn_dbufs_mtx); 2336 return (odb); 2337 } 2338 avl_add(&dn->dn_dbufs, db); 2339 2340 db->db_state = DB_UNCACHED; 2341 db->db_caching_status = DB_NO_CACHE; 2342 mutex_exit(&dn->dn_dbufs_mtx); 2343 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER); 2344 2345 if (parent && parent != dn->dn_dbuf) 2346 dbuf_add_ref(parent, db); 2347 2348 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT || 2349 zfs_refcount_count(&dn->dn_holds) > 0); 2350 (void) zfs_refcount_add(&dn->dn_holds, db); 2351 atomic_inc_32(&dn->dn_dbufs_count); 2352 2353 dprintf_dbuf(db, "db=%p\n", db); 2354 2355 return (db); 2356 } 2357 2358 typedef struct dbuf_prefetch_arg { 2359 spa_t *dpa_spa; /* The spa to issue the prefetch in. */ 2360 zbookmark_phys_t dpa_zb; /* The target block to prefetch. */ 2361 int dpa_epbs; /* Entries (blkptr_t's) Per Block Shift. */ 2362 int dpa_curlevel; /* The current level that we're reading */ 2363 dnode_t *dpa_dnode; /* The dnode associated with the prefetch */ 2364 zio_priority_t dpa_prio; /* The priority I/Os should be issued at. */ 2365 zio_t *dpa_zio; /* The parent zio_t for all prefetches. */ 2366 arc_flags_t dpa_aflags; /* Flags to pass to the final prefetch. */ 2367 } dbuf_prefetch_arg_t; 2368 2369 /* 2370 * Actually issue the prefetch read for the block given. 2371 */ 2372 static void 2373 dbuf_issue_final_prefetch(dbuf_prefetch_arg_t *dpa, blkptr_t *bp) 2374 { 2375 if (BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp)) 2376 return; 2377 2378 arc_flags_t aflags = 2379 dpa->dpa_aflags | ARC_FLAG_NOWAIT | ARC_FLAG_PREFETCH; 2380 2381 ASSERT3U(dpa->dpa_curlevel, ==, BP_GET_LEVEL(bp)); 2382 ASSERT3U(dpa->dpa_curlevel, ==, dpa->dpa_zb.zb_level); 2383 ASSERT(dpa->dpa_zio != NULL); 2384 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa, bp, NULL, NULL, 2385 dpa->dpa_prio, ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE, 2386 &aflags, &dpa->dpa_zb); 2387 } 2388 2389 /* 2390 * Called when an indirect block above our prefetch target is read in. This 2391 * will either read in the next indirect block down the tree or issue the actual 2392 * prefetch if the next block down is our target. 2393 */ 2394 static void 2395 dbuf_prefetch_indirect_done(zio_t *zio, arc_buf_t *abuf, void *private) 2396 { 2397 dbuf_prefetch_arg_t *dpa = private; 2398 2399 ASSERT3S(dpa->dpa_zb.zb_level, <, dpa->dpa_curlevel); 2400 ASSERT3S(dpa->dpa_curlevel, >, 0); 2401 2402 if (abuf == NULL) { 2403 ASSERT(zio == NULL || zio->io_error != 0); 2404 kmem_free(dpa, sizeof (*dpa)); 2405 return; 2406 } 2407 ASSERT(zio == NULL || zio->io_error == 0); 2408 2409 /* 2410 * The dpa_dnode is only valid if we are called with a NULL 2411 * zio. This indicates that the arc_read() returned without 2412 * first calling zio_read() to issue a physical read. Once 2413 * a physical read is made the dpa_dnode must be invalidated 2414 * as the locks guarding it may have been dropped. If the 2415 * dpa_dnode is still valid, then we want to add it to the dbuf 2416 * cache. To do so, we must hold the dbuf associated with the block 2417 * we just prefetched, read its contents so that we associate it 2418 * with an arc_buf_t, and then release it. 2419 */ 2420 if (zio != NULL) { 2421 ASSERT3S(BP_GET_LEVEL(zio->io_bp), ==, dpa->dpa_curlevel); 2422 if (zio->io_flags & ZIO_FLAG_RAW) { 2423 ASSERT3U(BP_GET_PSIZE(zio->io_bp), ==, zio->io_size); 2424 } else { 2425 ASSERT3U(BP_GET_LSIZE(zio->io_bp), ==, zio->io_size); 2426 } 2427 ASSERT3P(zio->io_spa, ==, dpa->dpa_spa); 2428 2429 dpa->dpa_dnode = NULL; 2430 } else if (dpa->dpa_dnode != NULL) { 2431 uint64_t curblkid = dpa->dpa_zb.zb_blkid >> 2432 (dpa->dpa_epbs * (dpa->dpa_curlevel - 2433 dpa->dpa_zb.zb_level)); 2434 dmu_buf_impl_t *db = dbuf_hold_level(dpa->dpa_dnode, 2435 dpa->dpa_curlevel, curblkid, FTAG); 2436 (void) dbuf_read(db, NULL, 2437 DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH | DB_RF_HAVESTRUCT); 2438 dbuf_rele(db, FTAG); 2439 } 2440 2441 dpa->dpa_curlevel--; 2442 2443 uint64_t nextblkid = dpa->dpa_zb.zb_blkid >> 2444 (dpa->dpa_epbs * (dpa->dpa_curlevel - dpa->dpa_zb.zb_level)); 2445 blkptr_t *bp = ((blkptr_t *)abuf->b_data) + 2446 P2PHASE(nextblkid, 1ULL << dpa->dpa_epbs); 2447 if (BP_IS_HOLE(bp)) { 2448 kmem_free(dpa, sizeof (*dpa)); 2449 } else if (dpa->dpa_curlevel == dpa->dpa_zb.zb_level) { 2450 ASSERT3U(nextblkid, ==, dpa->dpa_zb.zb_blkid); 2451 dbuf_issue_final_prefetch(dpa, bp); 2452 kmem_free(dpa, sizeof (*dpa)); 2453 } else { 2454 arc_flags_t iter_aflags = ARC_FLAG_NOWAIT; 2455 zbookmark_phys_t zb; 2456 2457 /* flag if L2ARC eligible, l2arc_noprefetch then decides */ 2458 if (dpa->dpa_aflags & ARC_FLAG_L2CACHE) 2459 iter_aflags |= ARC_FLAG_L2CACHE; 2460 2461 ASSERT3U(dpa->dpa_curlevel, ==, BP_GET_LEVEL(bp)); 2462 2463 SET_BOOKMARK(&zb, dpa->dpa_zb.zb_objset, 2464 dpa->dpa_zb.zb_object, dpa->dpa_curlevel, nextblkid); 2465 2466 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa, 2467 bp, dbuf_prefetch_indirect_done, dpa, dpa->dpa_prio, 2468 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE, 2469 &iter_aflags, &zb); 2470 } 2471 2472 arc_buf_destroy(abuf, private); 2473 } 2474 2475 /* 2476 * Issue prefetch reads for the given block on the given level. If the indirect 2477 * blocks above that block are not in memory, we will read them in 2478 * asynchronously. As a result, this call never blocks waiting for a read to 2479 * complete. 2480 */ 2481 void 2482 dbuf_prefetch(dnode_t *dn, int64_t level, uint64_t blkid, zio_priority_t prio, 2483 arc_flags_t aflags) 2484 { 2485 blkptr_t bp; 2486 int epbs, nlevels, curlevel; 2487 uint64_t curblkid; 2488 2489 ASSERT(blkid != DMU_BONUS_BLKID); 2490 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 2491 2492 if (blkid > dn->dn_maxblkid) 2493 return; 2494 2495 if (dnode_block_freed(dn, blkid)) 2496 return; 2497 2498 /* 2499 * This dnode hasn't been written to disk yet, so there's nothing to 2500 * prefetch. 2501 */ 2502 nlevels = dn->dn_phys->dn_nlevels; 2503 if (level >= nlevels || dn->dn_phys->dn_nblkptr == 0) 2504 return; 2505 2506 epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT; 2507 if (dn->dn_phys->dn_maxblkid < blkid << (epbs * level)) 2508 return; 2509 2510 dmu_buf_impl_t *db = dbuf_find(dn->dn_objset, dn->dn_object, 2511 level, blkid); 2512 if (db != NULL) { 2513 mutex_exit(&db->db_mtx); 2514 /* 2515 * This dbuf already exists. It is either CACHED, or 2516 * (we assume) about to be read or filled. 2517 */ 2518 return; 2519 } 2520 2521 /* 2522 * Find the closest ancestor (indirect block) of the target block 2523 * that is present in the cache. In this indirect block, we will 2524 * find the bp that is at curlevel, curblkid. 2525 */ 2526 curlevel = level; 2527 curblkid = blkid; 2528 while (curlevel < nlevels - 1) { 2529 int parent_level = curlevel + 1; 2530 uint64_t parent_blkid = curblkid >> epbs; 2531 dmu_buf_impl_t *db; 2532 2533 if (dbuf_hold_impl(dn, parent_level, parent_blkid, 2534 FALSE, TRUE, FTAG, &db) == 0) { 2535 blkptr_t *bpp = db->db_buf->b_data; 2536 bp = bpp[P2PHASE(curblkid, 1 << epbs)]; 2537 dbuf_rele(db, FTAG); 2538 break; 2539 } 2540 2541 curlevel = parent_level; 2542 curblkid = parent_blkid; 2543 } 2544 2545 if (curlevel == nlevels - 1) { 2546 /* No cached indirect blocks found. */ 2547 ASSERT3U(curblkid, <, dn->dn_phys->dn_nblkptr); 2548 bp = dn->dn_phys->dn_blkptr[curblkid]; 2549 } 2550 if (BP_IS_HOLE(&bp)) 2551 return; 2552 2553 ASSERT3U(curlevel, ==, BP_GET_LEVEL(&bp)); 2554 2555 zio_t *pio = zio_root(dmu_objset_spa(dn->dn_objset), NULL, NULL, 2556 ZIO_FLAG_CANFAIL); 2557 2558 dbuf_prefetch_arg_t *dpa = kmem_zalloc(sizeof (*dpa), KM_SLEEP); 2559 dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset; 2560 SET_BOOKMARK(&dpa->dpa_zb, ds != NULL ? ds->ds_object : DMU_META_OBJSET, 2561 dn->dn_object, level, blkid); 2562 dpa->dpa_curlevel = curlevel; 2563 dpa->dpa_prio = prio; 2564 dpa->dpa_aflags = aflags; 2565 dpa->dpa_spa = dn->dn_objset->os_spa; 2566 dpa->dpa_dnode = dn; 2567 dpa->dpa_epbs = epbs; 2568 dpa->dpa_zio = pio; 2569 2570 /* flag if L2ARC eligible, l2arc_noprefetch then decides */ 2571 if (DNODE_LEVEL_IS_L2CACHEABLE(dn, level)) 2572 dpa->dpa_aflags |= ARC_FLAG_L2CACHE; 2573 2574 /* 2575 * If we have the indirect just above us, no need to do the asynchronous 2576 * prefetch chain; we'll just run the last step ourselves. If we're at 2577 * a higher level, though, we want to issue the prefetches for all the 2578 * indirect blocks asynchronously, so we can go on with whatever we were 2579 * doing. 2580 */ 2581 if (curlevel == level) { 2582 ASSERT3U(curblkid, ==, blkid); 2583 dbuf_issue_final_prefetch(dpa, &bp); 2584 kmem_free(dpa, sizeof (*dpa)); 2585 } else { 2586 arc_flags_t iter_aflags = ARC_FLAG_NOWAIT; 2587 zbookmark_phys_t zb; 2588 2589 /* flag if L2ARC eligible, l2arc_noprefetch then decides */ 2590 if (DNODE_LEVEL_IS_L2CACHEABLE(dn, level)) 2591 iter_aflags |= ARC_FLAG_L2CACHE; 2592 2593 SET_BOOKMARK(&zb, ds != NULL ? ds->ds_object : DMU_META_OBJSET, 2594 dn->dn_object, curlevel, curblkid); 2595 (void) arc_read(dpa->dpa_zio, dpa->dpa_spa, 2596 &bp, dbuf_prefetch_indirect_done, dpa, prio, 2597 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE, 2598 &iter_aflags, &zb); 2599 } 2600 /* 2601 * We use pio here instead of dpa_zio since it's possible that 2602 * dpa may have already been freed. 2603 */ 2604 zio_nowait(pio); 2605 } 2606 2607 /* 2608 * Returns with db_holds incremented, and db_mtx not held. 2609 * Note: dn_struct_rwlock must be held. 2610 */ 2611 int 2612 dbuf_hold_impl(dnode_t *dn, uint8_t level, uint64_t blkid, 2613 boolean_t fail_sparse, boolean_t fail_uncached, 2614 void *tag, dmu_buf_impl_t **dbp) 2615 { 2616 dmu_buf_impl_t *db, *parent = NULL; 2617 2618 ASSERT(blkid != DMU_BONUS_BLKID); 2619 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 2620 ASSERT3U(dn->dn_nlevels, >, level); 2621 2622 *dbp = NULL; 2623 top: 2624 /* dbuf_find() returns with db_mtx held */ 2625 db = dbuf_find(dn->dn_objset, dn->dn_object, level, blkid); 2626 2627 if (db == NULL) { 2628 blkptr_t *bp = NULL; 2629 int err; 2630 2631 if (fail_uncached) 2632 return (SET_ERROR(ENOENT)); 2633 2634 ASSERT3P(parent, ==, NULL); 2635 err = dbuf_findbp(dn, level, blkid, fail_sparse, &parent, &bp); 2636 if (fail_sparse) { 2637 if (err == 0 && bp && BP_IS_HOLE(bp)) 2638 err = SET_ERROR(ENOENT); 2639 if (err) { 2640 if (parent) 2641 dbuf_rele(parent, NULL); 2642 return (err); 2643 } 2644 } 2645 if (err && err != ENOENT) 2646 return (err); 2647 db = dbuf_create(dn, level, blkid, parent, bp); 2648 } 2649 2650 if (fail_uncached && db->db_state != DB_CACHED) { 2651 mutex_exit(&db->db_mtx); 2652 return (SET_ERROR(ENOENT)); 2653 } 2654 2655 if (db->db_buf != NULL) { 2656 arc_buf_access(db->db_buf); 2657 ASSERT3P(db->db.db_data, ==, db->db_buf->b_data); 2658 } 2659 2660 ASSERT(db->db_buf == NULL || arc_referenced(db->db_buf)); 2661 2662 /* 2663 * If this buffer is currently syncing out, and we are are 2664 * still referencing it from db_data, we need to make a copy 2665 * of it in case we decide we want to dirty it again in this txg. 2666 */ 2667 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID && 2668 dn->dn_object != DMU_META_DNODE_OBJECT && 2669 db->db_state == DB_CACHED && db->db_data_pending) { 2670 dbuf_dirty_record_t *dr = db->db_data_pending; 2671 2672 if (dr->dt.dl.dr_data == db->db_buf) { 2673 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 2674 2675 dbuf_set_data(db, 2676 arc_alloc_buf(dn->dn_objset->os_spa, db, type, 2677 db->db.db_size)); 2678 bcopy(dr->dt.dl.dr_data->b_data, db->db.db_data, 2679 db->db.db_size); 2680 } 2681 } 2682 2683 if (multilist_link_active(&db->db_cache_link)) { 2684 ASSERT(zfs_refcount_is_zero(&db->db_holds)); 2685 ASSERT(db->db_caching_status == DB_DBUF_CACHE || 2686 db->db_caching_status == DB_DBUF_METADATA_CACHE); 2687 2688 multilist_remove(dbuf_caches[db->db_caching_status].cache, db); 2689 (void) zfs_refcount_remove_many( 2690 &dbuf_caches[db->db_caching_status].size, 2691 db->db.db_size, db); 2692 2693 db->db_caching_status = DB_NO_CACHE; 2694 } 2695 (void) zfs_refcount_add(&db->db_holds, tag); 2696 DBUF_VERIFY(db); 2697 mutex_exit(&db->db_mtx); 2698 2699 /* NOTE: we can't rele the parent until after we drop the db_mtx */ 2700 if (parent) 2701 dbuf_rele(parent, NULL); 2702 2703 ASSERT3P(DB_DNODE(db), ==, dn); 2704 ASSERT3U(db->db_blkid, ==, blkid); 2705 ASSERT3U(db->db_level, ==, level); 2706 *dbp = db; 2707 2708 return (0); 2709 } 2710 2711 dmu_buf_impl_t * 2712 dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag) 2713 { 2714 return (dbuf_hold_level(dn, 0, blkid, tag)); 2715 } 2716 2717 dmu_buf_impl_t * 2718 dbuf_hold_level(dnode_t *dn, int level, uint64_t blkid, void *tag) 2719 { 2720 dmu_buf_impl_t *db; 2721 int err = dbuf_hold_impl(dn, level, blkid, FALSE, FALSE, tag, &db); 2722 return (err ? NULL : db); 2723 } 2724 2725 void 2726 dbuf_create_bonus(dnode_t *dn) 2727 { 2728 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock)); 2729 2730 ASSERT(dn->dn_bonus == NULL); 2731 dn->dn_bonus = dbuf_create(dn, 0, DMU_BONUS_BLKID, dn->dn_dbuf, NULL); 2732 } 2733 2734 int 2735 dbuf_spill_set_blksz(dmu_buf_t *db_fake, uint64_t blksz, dmu_tx_t *tx) 2736 { 2737 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 2738 dnode_t *dn; 2739 2740 if (db->db_blkid != DMU_SPILL_BLKID) 2741 return (SET_ERROR(ENOTSUP)); 2742 if (blksz == 0) 2743 blksz = SPA_MINBLOCKSIZE; 2744 ASSERT3U(blksz, <=, spa_maxblocksize(dmu_objset_spa(db->db_objset))); 2745 blksz = P2ROUNDUP(blksz, SPA_MINBLOCKSIZE); 2746 2747 DB_DNODE_ENTER(db); 2748 dn = DB_DNODE(db); 2749 rw_enter(&dn->dn_struct_rwlock, RW_WRITER); 2750 dbuf_new_size(db, blksz, tx); 2751 rw_exit(&dn->dn_struct_rwlock); 2752 DB_DNODE_EXIT(db); 2753 2754 return (0); 2755 } 2756 2757 void 2758 dbuf_rm_spill(dnode_t *dn, dmu_tx_t *tx) 2759 { 2760 dbuf_free_range(dn, DMU_SPILL_BLKID, DMU_SPILL_BLKID, tx); 2761 } 2762 2763 #pragma weak dmu_buf_add_ref = dbuf_add_ref 2764 void 2765 dbuf_add_ref(dmu_buf_impl_t *db, void *tag) 2766 { 2767 int64_t holds = zfs_refcount_add(&db->db_holds, tag); 2768 ASSERT3S(holds, >, 1); 2769 } 2770 2771 #pragma weak dmu_buf_try_add_ref = dbuf_try_add_ref 2772 boolean_t 2773 dbuf_try_add_ref(dmu_buf_t *db_fake, objset_t *os, uint64_t obj, uint64_t blkid, 2774 void *tag) 2775 { 2776 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 2777 dmu_buf_impl_t *found_db; 2778 boolean_t result = B_FALSE; 2779 2780 if (db->db_blkid == DMU_BONUS_BLKID) 2781 found_db = dbuf_find_bonus(os, obj); 2782 else 2783 found_db = dbuf_find(os, obj, 0, blkid); 2784 2785 if (found_db != NULL) { 2786 if (db == found_db && dbuf_refcount(db) > db->db_dirtycnt) { 2787 (void) zfs_refcount_add(&db->db_holds, tag); 2788 result = B_TRUE; 2789 } 2790 mutex_exit(&db->db_mtx); 2791 } 2792 return (result); 2793 } 2794 2795 /* 2796 * If you call dbuf_rele() you had better not be referencing the dnode handle 2797 * unless you have some other direct or indirect hold on the dnode. (An indirect 2798 * hold is a hold on one of the dnode's dbufs, including the bonus buffer.) 2799 * Without that, the dbuf_rele() could lead to a dnode_rele() followed by the 2800 * dnode's parent dbuf evicting its dnode handles. 2801 */ 2802 void 2803 dbuf_rele(dmu_buf_impl_t *db, void *tag) 2804 { 2805 mutex_enter(&db->db_mtx); 2806 dbuf_rele_and_unlock(db, tag, B_FALSE); 2807 } 2808 2809 void 2810 dmu_buf_rele(dmu_buf_t *db, void *tag) 2811 { 2812 dbuf_rele((dmu_buf_impl_t *)db, tag); 2813 } 2814 2815 /* 2816 * dbuf_rele() for an already-locked dbuf. This is necessary to allow 2817 * db_dirtycnt and db_holds to be updated atomically. The 'evicting' 2818 * argument should be set if we are already in the dbuf-evicting code 2819 * path, in which case we don't want to recursively evict. This allows us to 2820 * avoid deeply nested stacks that would have a call flow similar to this: 2821 * 2822 * dbuf_rele()-->dbuf_rele_and_unlock()-->dbuf_evict_notify() 2823 * ^ | 2824 * | | 2825 * +-----dbuf_destroy()<--dbuf_evict_one()<--------+ 2826 * 2827 */ 2828 void 2829 dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag, boolean_t evicting) 2830 { 2831 int64_t holds; 2832 2833 ASSERT(MUTEX_HELD(&db->db_mtx)); 2834 DBUF_VERIFY(db); 2835 2836 /* 2837 * Remove the reference to the dbuf before removing its hold on the 2838 * dnode so we can guarantee in dnode_move() that a referenced bonus 2839 * buffer has a corresponding dnode hold. 2840 */ 2841 holds = zfs_refcount_remove(&db->db_holds, tag); 2842 ASSERT(holds >= 0); 2843 2844 /* 2845 * We can't freeze indirects if there is a possibility that they 2846 * may be modified in the current syncing context. 2847 */ 2848 if (db->db_buf != NULL && 2849 holds == (db->db_level == 0 ? db->db_dirtycnt : 0)) { 2850 arc_buf_freeze(db->db_buf); 2851 } 2852 2853 if (holds == db->db_dirtycnt && 2854 db->db_level == 0 && db->db_user_immediate_evict) 2855 dbuf_evict_user(db); 2856 2857 if (holds == 0) { 2858 if (db->db_blkid == DMU_BONUS_BLKID) { 2859 dnode_t *dn; 2860 boolean_t evict_dbuf = db->db_pending_evict; 2861 2862 /* 2863 * If the dnode moves here, we cannot cross this 2864 * barrier until the move completes. 2865 */ 2866 DB_DNODE_ENTER(db); 2867 2868 dn = DB_DNODE(db); 2869 atomic_dec_32(&dn->dn_dbufs_count); 2870 2871 /* 2872 * Decrementing the dbuf count means that the bonus 2873 * buffer's dnode hold is no longer discounted in 2874 * dnode_move(). The dnode cannot move until after 2875 * the dnode_rele() below. 2876 */ 2877 DB_DNODE_EXIT(db); 2878 2879 /* 2880 * Do not reference db after its lock is dropped. 2881 * Another thread may evict it. 2882 */ 2883 mutex_exit(&db->db_mtx); 2884 2885 if (evict_dbuf) 2886 dnode_evict_bonus(dn); 2887 2888 dnode_rele(dn, db); 2889 } else if (db->db_buf == NULL) { 2890 /* 2891 * This is a special case: we never associated this 2892 * dbuf with any data allocated from the ARC. 2893 */ 2894 ASSERT(db->db_state == DB_UNCACHED || 2895 db->db_state == DB_NOFILL); 2896 dbuf_destroy(db); 2897 } else if (arc_released(db->db_buf)) { 2898 /* 2899 * This dbuf has anonymous data associated with it. 2900 */ 2901 dbuf_destroy(db); 2902 } else { 2903 boolean_t do_arc_evict = B_FALSE; 2904 blkptr_t bp; 2905 spa_t *spa = dmu_objset_spa(db->db_objset); 2906 2907 if (!DBUF_IS_CACHEABLE(db) && 2908 db->db_blkptr != NULL && 2909 !BP_IS_HOLE(db->db_blkptr) && 2910 !BP_IS_EMBEDDED(db->db_blkptr)) { 2911 do_arc_evict = B_TRUE; 2912 bp = *db->db_blkptr; 2913 } 2914 2915 if (!DBUF_IS_CACHEABLE(db) || 2916 db->db_pending_evict) { 2917 dbuf_destroy(db); 2918 } else if (!multilist_link_active(&db->db_cache_link)) { 2919 ASSERT3U(db->db_caching_status, ==, 2920 DB_NO_CACHE); 2921 2922 dbuf_cached_state_t dcs = 2923 dbuf_include_in_metadata_cache(db) ? 2924 DB_DBUF_METADATA_CACHE : DB_DBUF_CACHE; 2925 db->db_caching_status = dcs; 2926 2927 multilist_insert(dbuf_caches[dcs].cache, db); 2928 (void) zfs_refcount_add_many( 2929 &dbuf_caches[dcs].size, db->db.db_size, db); 2930 mutex_exit(&db->db_mtx); 2931 2932 if (db->db_caching_status == DB_DBUF_CACHE && 2933 !evicting) { 2934 dbuf_evict_notify(); 2935 } 2936 } 2937 2938 if (do_arc_evict) 2939 arc_freed(spa, &bp); 2940 } 2941 } else { 2942 mutex_exit(&db->db_mtx); 2943 } 2944 2945 } 2946 2947 #pragma weak dmu_buf_refcount = dbuf_refcount 2948 uint64_t 2949 dbuf_refcount(dmu_buf_impl_t *db) 2950 { 2951 return (zfs_refcount_count(&db->db_holds)); 2952 } 2953 2954 void * 2955 dmu_buf_replace_user(dmu_buf_t *db_fake, dmu_buf_user_t *old_user, 2956 dmu_buf_user_t *new_user) 2957 { 2958 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 2959 2960 mutex_enter(&db->db_mtx); 2961 dbuf_verify_user(db, DBVU_NOT_EVICTING); 2962 if (db->db_user == old_user) 2963 db->db_user = new_user; 2964 else 2965 old_user = db->db_user; 2966 dbuf_verify_user(db, DBVU_NOT_EVICTING); 2967 mutex_exit(&db->db_mtx); 2968 2969 return (old_user); 2970 } 2971 2972 void * 2973 dmu_buf_set_user(dmu_buf_t *db_fake, dmu_buf_user_t *user) 2974 { 2975 return (dmu_buf_replace_user(db_fake, NULL, user)); 2976 } 2977 2978 void * 2979 dmu_buf_set_user_ie(dmu_buf_t *db_fake, dmu_buf_user_t *user) 2980 { 2981 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 2982 2983 db->db_user_immediate_evict = TRUE; 2984 return (dmu_buf_set_user(db_fake, user)); 2985 } 2986 2987 void * 2988 dmu_buf_remove_user(dmu_buf_t *db_fake, dmu_buf_user_t *user) 2989 { 2990 return (dmu_buf_replace_user(db_fake, user, NULL)); 2991 } 2992 2993 void * 2994 dmu_buf_get_user(dmu_buf_t *db_fake) 2995 { 2996 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 2997 2998 dbuf_verify_user(db, DBVU_NOT_EVICTING); 2999 return (db->db_user); 3000 } 3001 3002 void 3003 dmu_buf_user_evict_wait() 3004 { 3005 taskq_wait(dbu_evict_taskq); 3006 } 3007 3008 blkptr_t * 3009 dmu_buf_get_blkptr(dmu_buf_t *db) 3010 { 3011 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db; 3012 return (dbi->db_blkptr); 3013 } 3014 3015 objset_t * 3016 dmu_buf_get_objset(dmu_buf_t *db) 3017 { 3018 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db; 3019 return (dbi->db_objset); 3020 } 3021 3022 dnode_t * 3023 dmu_buf_dnode_enter(dmu_buf_t *db) 3024 { 3025 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db; 3026 DB_DNODE_ENTER(dbi); 3027 return (DB_DNODE(dbi)); 3028 } 3029 3030 void 3031 dmu_buf_dnode_exit(dmu_buf_t *db) 3032 { 3033 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db; 3034 DB_DNODE_EXIT(dbi); 3035 } 3036 3037 static void 3038 dbuf_check_blkptr(dnode_t *dn, dmu_buf_impl_t *db) 3039 { 3040 /* ASSERT(dmu_tx_is_syncing(tx) */ 3041 ASSERT(MUTEX_HELD(&db->db_mtx)); 3042 3043 if (db->db_blkptr != NULL) 3044 return; 3045 3046 if (db->db_blkid == DMU_SPILL_BLKID) { 3047 db->db_blkptr = DN_SPILL_BLKPTR(dn->dn_phys); 3048 BP_ZERO(db->db_blkptr); 3049 return; 3050 } 3051 if (db->db_level == dn->dn_phys->dn_nlevels-1) { 3052 /* 3053 * This buffer was allocated at a time when there was 3054 * no available blkptrs from the dnode, or it was 3055 * inappropriate to hook it in (i.e., nlevels mis-match). 3056 */ 3057 ASSERT(db->db_blkid < dn->dn_phys->dn_nblkptr); 3058 ASSERT(db->db_parent == NULL); 3059 db->db_parent = dn->dn_dbuf; 3060 db->db_blkptr = &dn->dn_phys->dn_blkptr[db->db_blkid]; 3061 DBUF_VERIFY(db); 3062 } else { 3063 dmu_buf_impl_t *parent = db->db_parent; 3064 int epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT; 3065 3066 ASSERT(dn->dn_phys->dn_nlevels > 1); 3067 if (parent == NULL) { 3068 mutex_exit(&db->db_mtx); 3069 rw_enter(&dn->dn_struct_rwlock, RW_READER); 3070 parent = dbuf_hold_level(dn, db->db_level + 1, 3071 db->db_blkid >> epbs, db); 3072 rw_exit(&dn->dn_struct_rwlock); 3073 mutex_enter(&db->db_mtx); 3074 db->db_parent = parent; 3075 } 3076 db->db_blkptr = (blkptr_t *)parent->db.db_data + 3077 (db->db_blkid & ((1ULL << epbs) - 1)); 3078 DBUF_VERIFY(db); 3079 } 3080 } 3081 3082 static void 3083 dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx) 3084 { 3085 dmu_buf_impl_t *db = dr->dr_dbuf; 3086 dnode_t *dn; 3087 zio_t *zio; 3088 3089 ASSERT(dmu_tx_is_syncing(tx)); 3090 3091 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr); 3092 3093 mutex_enter(&db->db_mtx); 3094 3095 ASSERT(db->db_level > 0); 3096 DBUF_VERIFY(db); 3097 3098 /* Read the block if it hasn't been read yet. */ 3099 if (db->db_buf == NULL) { 3100 mutex_exit(&db->db_mtx); 3101 (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED); 3102 mutex_enter(&db->db_mtx); 3103 } 3104 ASSERT3U(db->db_state, ==, DB_CACHED); 3105 ASSERT(db->db_buf != NULL); 3106 3107 DB_DNODE_ENTER(db); 3108 dn = DB_DNODE(db); 3109 /* Indirect block size must match what the dnode thinks it is. */ 3110 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift); 3111 dbuf_check_blkptr(dn, db); 3112 DB_DNODE_EXIT(db); 3113 3114 /* Provide the pending dirty record to child dbufs */ 3115 db->db_data_pending = dr; 3116 3117 mutex_exit(&db->db_mtx); 3118 3119 dbuf_write(dr, db->db_buf, tx); 3120 3121 zio = dr->dr_zio; 3122 mutex_enter(&dr->dt.di.dr_mtx); 3123 dbuf_sync_list(&dr->dt.di.dr_children, db->db_level - 1, tx); 3124 ASSERT(list_head(&dr->dt.di.dr_children) == NULL); 3125 mutex_exit(&dr->dt.di.dr_mtx); 3126 zio_nowait(zio); 3127 } 3128 3129 static void 3130 dbuf_sync_leaf(dbuf_dirty_record_t *dr, dmu_tx_t *tx) 3131 { 3132 arc_buf_t **datap = &dr->dt.dl.dr_data; 3133 dmu_buf_impl_t *db = dr->dr_dbuf; 3134 dnode_t *dn; 3135 objset_t *os; 3136 uint64_t txg = tx->tx_txg; 3137 3138 ASSERT(dmu_tx_is_syncing(tx)); 3139 3140 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr); 3141 3142 mutex_enter(&db->db_mtx); 3143 /* 3144 * To be synced, we must be dirtied. But we 3145 * might have been freed after the dirty. 3146 */ 3147 if (db->db_state == DB_UNCACHED) { 3148 /* This buffer has been freed since it was dirtied */ 3149 ASSERT(db->db.db_data == NULL); 3150 } else if (db->db_state == DB_FILL) { 3151 /* This buffer was freed and is now being re-filled */ 3152 ASSERT(db->db.db_data != dr->dt.dl.dr_data); 3153 } else { 3154 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_NOFILL); 3155 } 3156 DBUF_VERIFY(db); 3157 3158 DB_DNODE_ENTER(db); 3159 dn = DB_DNODE(db); 3160 3161 if (db->db_blkid == DMU_SPILL_BLKID) { 3162 mutex_enter(&dn->dn_mtx); 3163 dn->dn_phys->dn_flags |= DNODE_FLAG_SPILL_BLKPTR; 3164 mutex_exit(&dn->dn_mtx); 3165 } 3166 3167 /* 3168 * If this is a bonus buffer, simply copy the bonus data into the 3169 * dnode. It will be written out when the dnode is synced (and it 3170 * will be synced, since it must have been dirty for dbuf_sync to 3171 * be called). 3172 */ 3173 if (db->db_blkid == DMU_BONUS_BLKID) { 3174 dbuf_dirty_record_t **drp; 3175 3176 ASSERT(*datap != NULL); 3177 ASSERT0(db->db_level); 3178 ASSERT3U(DN_MAX_BONUS_LEN(dn->dn_phys), <=, 3179 DN_SLOTS_TO_BONUSLEN(dn->dn_phys->dn_extra_slots + 1)); 3180 bcopy(*datap, DN_BONUS(dn->dn_phys), 3181 DN_MAX_BONUS_LEN(dn->dn_phys)); 3182 DB_DNODE_EXIT(db); 3183 3184 if (*datap != db->db.db_data) { 3185 int slots = DB_DNODE(db)->dn_num_slots; 3186 int bonuslen = DN_SLOTS_TO_BONUSLEN(slots); 3187 zio_buf_free(*datap, bonuslen); 3188 arc_space_return(bonuslen, ARC_SPACE_BONUS); 3189 } 3190 db->db_data_pending = NULL; 3191 drp = &db->db_last_dirty; 3192 while (*drp != dr) 3193 drp = &(*drp)->dr_next; 3194 ASSERT(dr->dr_next == NULL); 3195 ASSERT(dr->dr_dbuf == db); 3196 *drp = dr->dr_next; 3197 kmem_free(dr, sizeof (dbuf_dirty_record_t)); 3198 ASSERT(db->db_dirtycnt > 0); 3199 db->db_dirtycnt -= 1; 3200 dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg, B_FALSE); 3201 return; 3202 } 3203 3204 os = dn->dn_objset; 3205 3206 /* 3207 * This function may have dropped the db_mtx lock allowing a dmu_sync 3208 * operation to sneak in. As a result, we need to ensure that we 3209 * don't check the dr_override_state until we have returned from 3210 * dbuf_check_blkptr. 3211 */ 3212 dbuf_check_blkptr(dn, db); 3213 3214 /* 3215 * If this buffer is in the middle of an immediate write, 3216 * wait for the synchronous IO to complete. 3217 */ 3218 while (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC) { 3219 ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT); 3220 cv_wait(&db->db_changed, &db->db_mtx); 3221 ASSERT(dr->dt.dl.dr_override_state != DR_NOT_OVERRIDDEN); 3222 } 3223 3224 if (db->db_state != DB_NOFILL && 3225 dn->dn_object != DMU_META_DNODE_OBJECT && 3226 zfs_refcount_count(&db->db_holds) > 1 && 3227 dr->dt.dl.dr_override_state != DR_OVERRIDDEN && 3228 *datap == db->db_buf) { 3229 /* 3230 * If this buffer is currently "in use" (i.e., there 3231 * are active holds and db_data still references it), 3232 * then make a copy before we start the write so that 3233 * any modifications from the open txg will not leak 3234 * into this write. 3235 * 3236 * NOTE: this copy does not need to be made for 3237 * objects only modified in the syncing context (e.g. 3238 * DNONE_DNODE blocks). 3239 */ 3240 int psize = arc_buf_size(*datap); 3241 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 3242 enum zio_compress compress_type = arc_get_compression(*datap); 3243 3244 if (compress_type == ZIO_COMPRESS_OFF) { 3245 *datap = arc_alloc_buf(os->os_spa, db, type, psize); 3246 } else { 3247 ASSERT3U(type, ==, ARC_BUFC_DATA); 3248 int lsize = arc_buf_lsize(*datap); 3249 *datap = arc_alloc_compressed_buf(os->os_spa, db, 3250 psize, lsize, compress_type); 3251 } 3252 bcopy(db->db.db_data, (*datap)->b_data, psize); 3253 } 3254 db->db_data_pending = dr; 3255 3256 mutex_exit(&db->db_mtx); 3257 3258 dbuf_write(dr, *datap, tx); 3259 3260 ASSERT(!list_link_active(&dr->dr_dirty_node)); 3261 if (dn->dn_object == DMU_META_DNODE_OBJECT) { 3262 list_insert_tail(&dn->dn_dirty_records[txg&TXG_MASK], dr); 3263 DB_DNODE_EXIT(db); 3264 } else { 3265 /* 3266 * Although zio_nowait() does not "wait for an IO", it does 3267 * initiate the IO. If this is an empty write it seems plausible 3268 * that the IO could actually be completed before the nowait 3269 * returns. We need to DB_DNODE_EXIT() first in case 3270 * zio_nowait() invalidates the dbuf. 3271 */ 3272 DB_DNODE_EXIT(db); 3273 zio_nowait(dr->dr_zio); 3274 } 3275 } 3276 3277 void 3278 dbuf_sync_list(list_t *list, int level, dmu_tx_t *tx) 3279 { 3280 dbuf_dirty_record_t *dr; 3281 3282 while (dr = list_head(list)) { 3283 if (dr->dr_zio != NULL) { 3284 /* 3285 * If we find an already initialized zio then we 3286 * are processing the meta-dnode, and we have finished. 3287 * The dbufs for all dnodes are put back on the list 3288 * during processing, so that we can zio_wait() 3289 * these IOs after initiating all child IOs. 3290 */ 3291 ASSERT3U(dr->dr_dbuf->db.db_object, ==, 3292 DMU_META_DNODE_OBJECT); 3293 break; 3294 } 3295 if (dr->dr_dbuf->db_blkid != DMU_BONUS_BLKID && 3296 dr->dr_dbuf->db_blkid != DMU_SPILL_BLKID) { 3297 VERIFY3U(dr->dr_dbuf->db_level, ==, level); 3298 } 3299 list_remove(list, dr); 3300 if (dr->dr_dbuf->db_level > 0) 3301 dbuf_sync_indirect(dr, tx); 3302 else 3303 dbuf_sync_leaf(dr, tx); 3304 } 3305 } 3306 3307 /* ARGSUSED */ 3308 static void 3309 dbuf_write_ready(zio_t *zio, arc_buf_t *buf, void *vdb) 3310 { 3311 dmu_buf_impl_t *db = vdb; 3312 dnode_t *dn; 3313 blkptr_t *bp = zio->io_bp; 3314 blkptr_t *bp_orig = &zio->io_bp_orig; 3315 spa_t *spa = zio->io_spa; 3316 int64_t delta; 3317 uint64_t fill = 0; 3318 int i; 3319 3320 ASSERT3P(db->db_blkptr, !=, NULL); 3321 ASSERT3P(&db->db_data_pending->dr_bp_copy, ==, bp); 3322 3323 DB_DNODE_ENTER(db); 3324 dn = DB_DNODE(db); 3325 delta = bp_get_dsize_sync(spa, bp) - bp_get_dsize_sync(spa, bp_orig); 3326 dnode_diduse_space(dn, delta - zio->io_prev_space_delta); 3327 zio->io_prev_space_delta = delta; 3328 3329 if (bp->blk_birth != 0) { 3330 ASSERT((db->db_blkid != DMU_SPILL_BLKID && 3331 BP_GET_TYPE(bp) == dn->dn_type) || 3332 (db->db_blkid == DMU_SPILL_BLKID && 3333 BP_GET_TYPE(bp) == dn->dn_bonustype) || 3334 BP_IS_EMBEDDED(bp)); 3335 ASSERT(BP_GET_LEVEL(bp) == db->db_level); 3336 } 3337 3338 mutex_enter(&db->db_mtx); 3339 3340 #ifdef ZFS_DEBUG 3341 if (db->db_blkid == DMU_SPILL_BLKID) { 3342 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR); 3343 ASSERT(!(BP_IS_HOLE(bp)) && 3344 db->db_blkptr == DN_SPILL_BLKPTR(dn->dn_phys)); 3345 } 3346 #endif 3347 3348 if (db->db_level == 0) { 3349 mutex_enter(&dn->dn_mtx); 3350 if (db->db_blkid > dn->dn_phys->dn_maxblkid && 3351 db->db_blkid != DMU_SPILL_BLKID) 3352 dn->dn_phys->dn_maxblkid = db->db_blkid; 3353 mutex_exit(&dn->dn_mtx); 3354 3355 if (dn->dn_type == DMU_OT_DNODE) { 3356 i = 0; 3357 while (i < db->db.db_size) { 3358 dnode_phys_t *dnp = 3359 (void *)(((char *)db->db.db_data) + i); 3360 3361 i += DNODE_MIN_SIZE; 3362 if (dnp->dn_type != DMU_OT_NONE) { 3363 fill++; 3364 i += dnp->dn_extra_slots * 3365 DNODE_MIN_SIZE; 3366 } 3367 } 3368 } else { 3369 if (BP_IS_HOLE(bp)) { 3370 fill = 0; 3371 } else { 3372 fill = 1; 3373 } 3374 } 3375 } else { 3376 blkptr_t *ibp = db->db.db_data; 3377 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift); 3378 for (i = db->db.db_size >> SPA_BLKPTRSHIFT; i > 0; i--, ibp++) { 3379 if (BP_IS_HOLE(ibp)) 3380 continue; 3381 fill += BP_GET_FILL(ibp); 3382 } 3383 } 3384 DB_DNODE_EXIT(db); 3385 3386 if (!BP_IS_EMBEDDED(bp)) 3387 bp->blk_fill = fill; 3388 3389 mutex_exit(&db->db_mtx); 3390 3391 rw_enter(&dn->dn_struct_rwlock, RW_WRITER); 3392 *db->db_blkptr = *bp; 3393 rw_exit(&dn->dn_struct_rwlock); 3394 } 3395 3396 /* ARGSUSED */ 3397 /* 3398 * This function gets called just prior to running through the compression 3399 * stage of the zio pipeline. If we're an indirect block comprised of only 3400 * holes, then we want this indirect to be compressed away to a hole. In 3401 * order to do that we must zero out any information about the holes that 3402 * this indirect points to prior to before we try to compress it. 3403 */ 3404 static void 3405 dbuf_write_children_ready(zio_t *zio, arc_buf_t *buf, void *vdb) 3406 { 3407 dmu_buf_impl_t *db = vdb; 3408 dnode_t *dn; 3409 blkptr_t *bp; 3410 unsigned int epbs, i; 3411 3412 ASSERT3U(db->db_level, >, 0); 3413 DB_DNODE_ENTER(db); 3414 dn = DB_DNODE(db); 3415 epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT; 3416 ASSERT3U(epbs, <, 31); 3417 3418 /* Determine if all our children are holes */ 3419 for (i = 0, bp = db->db.db_data; i < 1 << epbs; i++, bp++) { 3420 if (!BP_IS_HOLE(bp)) 3421 break; 3422 } 3423 3424 /* 3425 * If all the children are holes, then zero them all out so that 3426 * we may get compressed away. 3427 */ 3428 if (i == 1 << epbs) { 3429 /* 3430 * We only found holes. Grab the rwlock to prevent 3431 * anybody from reading the blocks we're about to 3432 * zero out. 3433 */ 3434 rw_enter(&dn->dn_struct_rwlock, RW_WRITER); 3435 bzero(db->db.db_data, db->db.db_size); 3436 rw_exit(&dn->dn_struct_rwlock); 3437 } 3438 DB_DNODE_EXIT(db); 3439 } 3440 3441 /* 3442 * The SPA will call this callback several times for each zio - once 3443 * for every physical child i/o (zio->io_phys_children times). This 3444 * allows the DMU to monitor the progress of each logical i/o. For example, 3445 * there may be 2 copies of an indirect block, or many fragments of a RAID-Z 3446 * block. There may be a long delay before all copies/fragments are completed, 3447 * so this callback allows us to retire dirty space gradually, as the physical 3448 * i/os complete. 3449 */ 3450 /* ARGSUSED */ 3451 static void 3452 dbuf_write_physdone(zio_t *zio, arc_buf_t *buf, void *arg) 3453 { 3454 dmu_buf_impl_t *db = arg; 3455 objset_t *os = db->db_objset; 3456 dsl_pool_t *dp = dmu_objset_pool(os); 3457 dbuf_dirty_record_t *dr; 3458 int delta = 0; 3459 3460 dr = db->db_data_pending; 3461 ASSERT3U(dr->dr_txg, ==, zio->io_txg); 3462 3463 /* 3464 * The callback will be called io_phys_children times. Retire one 3465 * portion of our dirty space each time we are called. Any rounding 3466 * error will be cleaned up by dsl_pool_sync()'s call to 3467 * dsl_pool_undirty_space(). 3468 */ 3469 delta = dr->dr_accounted / zio->io_phys_children; 3470 dsl_pool_undirty_space(dp, delta, zio->io_txg); 3471 } 3472 3473 /* ARGSUSED */ 3474 static void 3475 dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb) 3476 { 3477 dmu_buf_impl_t *db = vdb; 3478 blkptr_t *bp_orig = &zio->io_bp_orig; 3479 blkptr_t *bp = db->db_blkptr; 3480 objset_t *os = db->db_objset; 3481 dmu_tx_t *tx = os->os_synctx; 3482 dbuf_dirty_record_t **drp, *dr; 3483 3484 ASSERT0(zio->io_error); 3485 ASSERT(db->db_blkptr == bp); 3486 3487 /* 3488 * For nopwrites and rewrites we ensure that the bp matches our 3489 * original and bypass all the accounting. 3490 */ 3491 if (zio->io_flags & (ZIO_FLAG_IO_REWRITE | ZIO_FLAG_NOPWRITE)) { 3492 ASSERT(BP_EQUAL(bp, bp_orig)); 3493 } else { 3494 dsl_dataset_t *ds = os->os_dsl_dataset; 3495 (void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE); 3496 dsl_dataset_block_born(ds, bp, tx); 3497 } 3498 3499 mutex_enter(&db->db_mtx); 3500 3501 DBUF_VERIFY(db); 3502 3503 drp = &db->db_last_dirty; 3504 while ((dr = *drp) != db->db_data_pending) 3505 drp = &dr->dr_next; 3506 ASSERT(!list_link_active(&dr->dr_dirty_node)); 3507 ASSERT(dr->dr_dbuf == db); 3508 ASSERT(dr->dr_next == NULL); 3509 *drp = dr->dr_next; 3510 3511 #ifdef ZFS_DEBUG 3512 if (db->db_blkid == DMU_SPILL_BLKID) { 3513 dnode_t *dn; 3514 3515 DB_DNODE_ENTER(db); 3516 dn = DB_DNODE(db); 3517 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR); 3518 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) && 3519 db->db_blkptr == DN_SPILL_BLKPTR(dn->dn_phys)); 3520 DB_DNODE_EXIT(db); 3521 } 3522 #endif 3523 3524 if (db->db_level == 0) { 3525 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 3526 ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN); 3527 if (db->db_state != DB_NOFILL) { 3528 if (dr->dt.dl.dr_data != db->db_buf) 3529 arc_buf_destroy(dr->dt.dl.dr_data, db); 3530 } 3531 } else { 3532 dnode_t *dn; 3533 3534 DB_DNODE_ENTER(db); 3535 dn = DB_DNODE(db); 3536 ASSERT(list_head(&dr->dt.di.dr_children) == NULL); 3537 ASSERT3U(db->db.db_size, ==, 1 << dn->dn_phys->dn_indblkshift); 3538 if (!BP_IS_HOLE(db->db_blkptr)) { 3539 int epbs = 3540 dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT; 3541 ASSERT3U(db->db_blkid, <=, 3542 dn->dn_phys->dn_maxblkid >> (db->db_level * epbs)); 3543 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==, 3544 db->db.db_size); 3545 } 3546 DB_DNODE_EXIT(db); 3547 mutex_destroy(&dr->dt.di.dr_mtx); 3548 list_destroy(&dr->dt.di.dr_children); 3549 } 3550 kmem_free(dr, sizeof (dbuf_dirty_record_t)); 3551 3552 cv_broadcast(&db->db_changed); 3553 ASSERT(db->db_dirtycnt > 0); 3554 db->db_dirtycnt -= 1; 3555 db->db_data_pending = NULL; 3556 dbuf_rele_and_unlock(db, (void *)(uintptr_t)tx->tx_txg, B_FALSE); 3557 } 3558 3559 static void 3560 dbuf_write_nofill_ready(zio_t *zio) 3561 { 3562 dbuf_write_ready(zio, NULL, zio->io_private); 3563 } 3564 3565 static void 3566 dbuf_write_nofill_done(zio_t *zio) 3567 { 3568 dbuf_write_done(zio, NULL, zio->io_private); 3569 } 3570 3571 static void 3572 dbuf_write_override_ready(zio_t *zio) 3573 { 3574 dbuf_dirty_record_t *dr = zio->io_private; 3575 dmu_buf_impl_t *db = dr->dr_dbuf; 3576 3577 dbuf_write_ready(zio, NULL, db); 3578 } 3579 3580 static void 3581 dbuf_write_override_done(zio_t *zio) 3582 { 3583 dbuf_dirty_record_t *dr = zio->io_private; 3584 dmu_buf_impl_t *db = dr->dr_dbuf; 3585 blkptr_t *obp = &dr->dt.dl.dr_overridden_by; 3586 3587 mutex_enter(&db->db_mtx); 3588 if (!BP_EQUAL(zio->io_bp, obp)) { 3589 if (!BP_IS_HOLE(obp)) 3590 dsl_free(spa_get_dsl(zio->io_spa), zio->io_txg, obp); 3591 arc_release(dr->dt.dl.dr_data, db); 3592 } 3593 mutex_exit(&db->db_mtx); 3594 dbuf_write_done(zio, NULL, db); 3595 3596 if (zio->io_abd != NULL) 3597 abd_put(zio->io_abd); 3598 } 3599 3600 typedef struct dbuf_remap_impl_callback_arg { 3601 objset_t *drica_os; 3602 uint64_t drica_blk_birth; 3603 dmu_tx_t *drica_tx; 3604 } dbuf_remap_impl_callback_arg_t; 3605 3606 static void 3607 dbuf_remap_impl_callback(uint64_t vdev, uint64_t offset, uint64_t size, 3608 void *arg) 3609 { 3610 dbuf_remap_impl_callback_arg_t *drica = arg; 3611 objset_t *os = drica->drica_os; 3612 spa_t *spa = dmu_objset_spa(os); 3613 dmu_tx_t *tx = drica->drica_tx; 3614 3615 ASSERT(dsl_pool_sync_context(spa_get_dsl(spa))); 3616 3617 if (os == spa_meta_objset(spa)) { 3618 spa_vdev_indirect_mark_obsolete(spa, vdev, offset, size, tx); 3619 } else { 3620 dsl_dataset_block_remapped(dmu_objset_ds(os), vdev, offset, 3621 size, drica->drica_blk_birth, tx); 3622 } 3623 } 3624 3625 static void 3626 dbuf_remap_impl(dnode_t *dn, blkptr_t *bp, dmu_tx_t *tx) 3627 { 3628 blkptr_t bp_copy = *bp; 3629 spa_t *spa = dmu_objset_spa(dn->dn_objset); 3630 dbuf_remap_impl_callback_arg_t drica; 3631 3632 ASSERT(dsl_pool_sync_context(spa_get_dsl(spa))); 3633 3634 drica.drica_os = dn->dn_objset; 3635 drica.drica_blk_birth = bp->blk_birth; 3636 drica.drica_tx = tx; 3637 if (spa_remap_blkptr(spa, &bp_copy, dbuf_remap_impl_callback, 3638 &drica)) { 3639 /* 3640 * The struct_rwlock prevents dbuf_read_impl() from 3641 * dereferencing the BP while we are changing it. To 3642 * avoid lock contention, only grab it when we are actually 3643 * changing the BP. 3644 */ 3645 rw_enter(&dn->dn_struct_rwlock, RW_WRITER); 3646 *bp = bp_copy; 3647 rw_exit(&dn->dn_struct_rwlock); 3648 } 3649 } 3650 3651 /* 3652 * Returns true if a dbuf_remap would modify the dbuf. We do this by attempting 3653 * to remap a copy of every bp in the dbuf. 3654 */ 3655 boolean_t 3656 dbuf_can_remap(const dmu_buf_impl_t *db) 3657 { 3658 spa_t *spa = dmu_objset_spa(db->db_objset); 3659 blkptr_t *bp = db->db.db_data; 3660 boolean_t ret = B_FALSE; 3661 3662 ASSERT3U(db->db_level, >, 0); 3663 ASSERT3S(db->db_state, ==, DB_CACHED); 3664 3665 ASSERT(spa_feature_is_active(spa, SPA_FEATURE_DEVICE_REMOVAL)); 3666 3667 spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER); 3668 for (int i = 0; i < db->db.db_size >> SPA_BLKPTRSHIFT; i++) { 3669 blkptr_t bp_copy = bp[i]; 3670 if (spa_remap_blkptr(spa, &bp_copy, NULL, NULL)) { 3671 ret = B_TRUE; 3672 break; 3673 } 3674 } 3675 spa_config_exit(spa, SCL_VDEV, FTAG); 3676 3677 return (ret); 3678 } 3679 3680 boolean_t 3681 dnode_needs_remap(const dnode_t *dn) 3682 { 3683 spa_t *spa = dmu_objset_spa(dn->dn_objset); 3684 boolean_t ret = B_FALSE; 3685 3686 if (dn->dn_phys->dn_nlevels == 0) { 3687 return (B_FALSE); 3688 } 3689 3690 ASSERT(spa_feature_is_active(spa, SPA_FEATURE_DEVICE_REMOVAL)); 3691 3692 spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER); 3693 for (int j = 0; j < dn->dn_phys->dn_nblkptr; j++) { 3694 blkptr_t bp_copy = dn->dn_phys->dn_blkptr[j]; 3695 if (spa_remap_blkptr(spa, &bp_copy, NULL, NULL)) { 3696 ret = B_TRUE; 3697 break; 3698 } 3699 } 3700 spa_config_exit(spa, SCL_VDEV, FTAG); 3701 3702 return (ret); 3703 } 3704 3705 /* 3706 * Remap any existing BP's to concrete vdevs, if possible. 3707 */ 3708 static void 3709 dbuf_remap(dnode_t *dn, dmu_buf_impl_t *db, dmu_tx_t *tx) 3710 { 3711 spa_t *spa = dmu_objset_spa(db->db_objset); 3712 ASSERT(dsl_pool_sync_context(spa_get_dsl(spa))); 3713 3714 if (!spa_feature_is_active(spa, SPA_FEATURE_DEVICE_REMOVAL)) 3715 return; 3716 3717 if (db->db_level > 0) { 3718 blkptr_t *bp = db->db.db_data; 3719 for (int i = 0; i < db->db.db_size >> SPA_BLKPTRSHIFT; i++) { 3720 dbuf_remap_impl(dn, &bp[i], tx); 3721 } 3722 } else if (db->db.db_object == DMU_META_DNODE_OBJECT) { 3723 dnode_phys_t *dnp = db->db.db_data; 3724 ASSERT3U(db->db_dnode_handle->dnh_dnode->dn_type, ==, 3725 DMU_OT_DNODE); 3726 for (int i = 0; i < db->db.db_size >> DNODE_SHIFT; i++) { 3727 for (int j = 0; j < dnp[i].dn_nblkptr; j++) { 3728 dbuf_remap_impl(dn, &dnp[i].dn_blkptr[j], tx); 3729 } 3730 } 3731 } 3732 } 3733 3734 3735 /* Issue I/O to commit a dirty buffer to disk. */ 3736 static void 3737 dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx) 3738 { 3739 dmu_buf_impl_t *db = dr->dr_dbuf; 3740 dnode_t *dn; 3741 objset_t *os; 3742 dmu_buf_impl_t *parent = db->db_parent; 3743 uint64_t txg = tx->tx_txg; 3744 zbookmark_phys_t zb; 3745 zio_prop_t zp; 3746 zio_t *zio; 3747 int wp_flag = 0; 3748 3749 ASSERT(dmu_tx_is_syncing(tx)); 3750 3751 DB_DNODE_ENTER(db); 3752 dn = DB_DNODE(db); 3753 os = dn->dn_objset; 3754 3755 if (db->db_state != DB_NOFILL) { 3756 if (db->db_level > 0 || dn->dn_type == DMU_OT_DNODE) { 3757 /* 3758 * Private object buffers are released here rather 3759 * than in dbuf_dirty() since they are only modified 3760 * in the syncing context and we don't want the 3761 * overhead of making multiple copies of the data. 3762 */ 3763 if (BP_IS_HOLE(db->db_blkptr)) { 3764 arc_buf_thaw(data); 3765 } else { 3766 dbuf_release_bp(db); 3767 } 3768 dbuf_remap(dn, db, tx); 3769 } 3770 } 3771 3772 if (parent != dn->dn_dbuf) { 3773 /* Our parent is an indirect block. */ 3774 /* We have a dirty parent that has been scheduled for write. */ 3775 ASSERT(parent && parent->db_data_pending); 3776 /* Our parent's buffer is one level closer to the dnode. */ 3777 ASSERT(db->db_level == parent->db_level-1); 3778 /* 3779 * We're about to modify our parent's db_data by modifying 3780 * our block pointer, so the parent must be released. 3781 */ 3782 ASSERT(arc_released(parent->db_buf)); 3783 zio = parent->db_data_pending->dr_zio; 3784 } else { 3785 /* Our parent is the dnode itself. */ 3786 ASSERT((db->db_level == dn->dn_phys->dn_nlevels-1 && 3787 db->db_blkid != DMU_SPILL_BLKID) || 3788 (db->db_blkid == DMU_SPILL_BLKID && db->db_level == 0)); 3789 if (db->db_blkid != DMU_SPILL_BLKID) 3790 ASSERT3P(db->db_blkptr, ==, 3791 &dn->dn_phys->dn_blkptr[db->db_blkid]); 3792 zio = dn->dn_zio; 3793 } 3794 3795 ASSERT(db->db_level == 0 || data == db->db_buf); 3796 ASSERT3U(db->db_blkptr->blk_birth, <=, txg); 3797 ASSERT(zio); 3798 3799 SET_BOOKMARK(&zb, os->os_dsl_dataset ? 3800 os->os_dsl_dataset->ds_object : DMU_META_OBJSET, 3801 db->db.db_object, db->db_level, db->db_blkid); 3802 3803 if (db->db_blkid == DMU_SPILL_BLKID) 3804 wp_flag = WP_SPILL; 3805 wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0; 3806 3807 dmu_write_policy(os, dn, db->db_level, wp_flag, &zp); 3808 DB_DNODE_EXIT(db); 3809 3810 /* 3811 * We copy the blkptr now (rather than when we instantiate the dirty 3812 * record), because its value can change between open context and 3813 * syncing context. We do not need to hold dn_struct_rwlock to read 3814 * db_blkptr because we are in syncing context. 3815 */ 3816 dr->dr_bp_copy = *db->db_blkptr; 3817 3818 if (db->db_level == 0 && 3819 dr->dt.dl.dr_override_state == DR_OVERRIDDEN) { 3820 /* 3821 * The BP for this block has been provided by open context 3822 * (by dmu_sync() or dmu_buf_write_embedded()). 3823 */ 3824 abd_t *contents = (data != NULL) ? 3825 abd_get_from_buf(data->b_data, arc_buf_size(data)) : NULL; 3826 3827 dr->dr_zio = zio_write(zio, os->os_spa, txg, &dr->dr_bp_copy, 3828 contents, db->db.db_size, db->db.db_size, &zp, 3829 dbuf_write_override_ready, NULL, NULL, 3830 dbuf_write_override_done, 3831 dr, ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb); 3832 mutex_enter(&db->db_mtx); 3833 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN; 3834 zio_write_override(dr->dr_zio, &dr->dt.dl.dr_overridden_by, 3835 dr->dt.dl.dr_copies, dr->dt.dl.dr_nopwrite); 3836 mutex_exit(&db->db_mtx); 3837 } else if (db->db_state == DB_NOFILL) { 3838 ASSERT(zp.zp_checksum == ZIO_CHECKSUM_OFF || 3839 zp.zp_checksum == ZIO_CHECKSUM_NOPARITY); 3840 dr->dr_zio = zio_write(zio, os->os_spa, txg, 3841 &dr->dr_bp_copy, NULL, db->db.db_size, db->db.db_size, &zp, 3842 dbuf_write_nofill_ready, NULL, NULL, 3843 dbuf_write_nofill_done, db, 3844 ZIO_PRIORITY_ASYNC_WRITE, 3845 ZIO_FLAG_MUSTSUCCEED | ZIO_FLAG_NODATA, &zb); 3846 } else { 3847 ASSERT(arc_released(data)); 3848 3849 /* 3850 * For indirect blocks, we want to setup the children 3851 * ready callback so that we can properly handle an indirect 3852 * block that only contains holes. 3853 */ 3854 arc_done_func_t *children_ready_cb = NULL; 3855 if (db->db_level != 0) 3856 children_ready_cb = dbuf_write_children_ready; 3857 3858 dr->dr_zio = arc_write(zio, os->os_spa, txg, 3859 &dr->dr_bp_copy, data, DBUF_IS_L2CACHEABLE(db), 3860 &zp, dbuf_write_ready, children_ready_cb, 3861 dbuf_write_physdone, dbuf_write_done, db, 3862 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb); 3863 } 3864 } 3865