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