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) 2013 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 */ 28 29 #include <sys/zfs_context.h> 30 #include <sys/dmu.h> 31 #include <sys/dmu_send.h> 32 #include <sys/dmu_impl.h> 33 #include <sys/dbuf.h> 34 #include <sys/dmu_objset.h> 35 #include <sys/dsl_dataset.h> 36 #include <sys/dsl_dir.h> 37 #include <sys/dmu_tx.h> 38 #include <sys/spa.h> 39 #include <sys/zio.h> 40 #include <sys/dmu_zfetch.h> 41 #include <sys/sa.h> 42 #include <sys/sa_impl.h> 43 44 /* 45 * Number of times that zfs_free_range() took the slow path while doing 46 * a zfs receive. A nonzero value indicates a potential performance problem. 47 */ 48 uint64_t zfs_free_range_recv_miss; 49 50 static void dbuf_destroy(dmu_buf_impl_t *db); 51 static boolean_t dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx); 52 static void dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx); 53 54 /* 55 * Global data structures and functions for the dbuf cache. 56 */ 57 static kmem_cache_t *dbuf_cache; 58 59 /* ARGSUSED */ 60 static int 61 dbuf_cons(void *vdb, void *unused, int kmflag) 62 { 63 dmu_buf_impl_t *db = vdb; 64 bzero(db, sizeof (dmu_buf_impl_t)); 65 66 mutex_init(&db->db_mtx, NULL, MUTEX_DEFAULT, NULL); 67 cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL); 68 refcount_create(&db->db_holds); 69 return (0); 70 } 71 72 /* ARGSUSED */ 73 static void 74 dbuf_dest(void *vdb, void *unused) 75 { 76 dmu_buf_impl_t *db = vdb; 77 mutex_destroy(&db->db_mtx); 78 cv_destroy(&db->db_changed); 79 refcount_destroy(&db->db_holds); 80 } 81 82 /* 83 * dbuf hash table routines 84 */ 85 static dbuf_hash_table_t dbuf_hash_table; 86 87 static uint64_t dbuf_hash_count; 88 89 static uint64_t 90 dbuf_hash(void *os, uint64_t obj, uint8_t lvl, uint64_t blkid) 91 { 92 uintptr_t osv = (uintptr_t)os; 93 uint64_t crc = -1ULL; 94 95 ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY); 96 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (lvl)) & 0xFF]; 97 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (osv >> 6)) & 0xFF]; 98 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 0)) & 0xFF]; 99 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 8)) & 0xFF]; 100 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 0)) & 0xFF]; 101 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 8)) & 0xFF]; 102 103 crc ^= (osv>>14) ^ (obj>>16) ^ (blkid>>16); 104 105 return (crc); 106 } 107 108 #define DBUF_HASH(os, obj, level, blkid) dbuf_hash(os, obj, level, blkid); 109 110 #define DBUF_EQUAL(dbuf, os, obj, level, blkid) \ 111 ((dbuf)->db.db_object == (obj) && \ 112 (dbuf)->db_objset == (os) && \ 113 (dbuf)->db_level == (level) && \ 114 (dbuf)->db_blkid == (blkid)) 115 116 dmu_buf_impl_t * 117 dbuf_find(dnode_t *dn, uint8_t level, uint64_t blkid) 118 { 119 dbuf_hash_table_t *h = &dbuf_hash_table; 120 objset_t *os = dn->dn_objset; 121 uint64_t obj = dn->dn_object; 122 uint64_t hv = DBUF_HASH(os, obj, level, blkid); 123 uint64_t idx = hv & h->hash_table_mask; 124 dmu_buf_impl_t *db; 125 126 mutex_enter(DBUF_HASH_MUTEX(h, idx)); 127 for (db = h->hash_table[idx]; db != NULL; db = db->db_hash_next) { 128 if (DBUF_EQUAL(db, os, obj, level, blkid)) { 129 mutex_enter(&db->db_mtx); 130 if (db->db_state != DB_EVICTING) { 131 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 132 return (db); 133 } 134 mutex_exit(&db->db_mtx); 135 } 136 } 137 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 138 return (NULL); 139 } 140 141 /* 142 * Insert an entry into the hash table. If there is already an element 143 * equal to elem in the hash table, then the already existing element 144 * will be returned and the new element will not be inserted. 145 * Otherwise returns NULL. 146 */ 147 static dmu_buf_impl_t * 148 dbuf_hash_insert(dmu_buf_impl_t *db) 149 { 150 dbuf_hash_table_t *h = &dbuf_hash_table; 151 objset_t *os = db->db_objset; 152 uint64_t obj = db->db.db_object; 153 int level = db->db_level; 154 uint64_t blkid = db->db_blkid; 155 uint64_t hv = DBUF_HASH(os, obj, level, blkid); 156 uint64_t idx = hv & h->hash_table_mask; 157 dmu_buf_impl_t *dbf; 158 159 mutex_enter(DBUF_HASH_MUTEX(h, idx)); 160 for (dbf = h->hash_table[idx]; dbf != NULL; dbf = dbf->db_hash_next) { 161 if (DBUF_EQUAL(dbf, os, obj, level, blkid)) { 162 mutex_enter(&dbf->db_mtx); 163 if (dbf->db_state != DB_EVICTING) { 164 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 165 return (dbf); 166 } 167 mutex_exit(&dbf->db_mtx); 168 } 169 } 170 171 mutex_enter(&db->db_mtx); 172 db->db_hash_next = h->hash_table[idx]; 173 h->hash_table[idx] = db; 174 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 175 atomic_add_64(&dbuf_hash_count, 1); 176 177 return (NULL); 178 } 179 180 /* 181 * Remove an entry from the hash table. This operation will 182 * fail if there are any existing holds on the db. 183 */ 184 static void 185 dbuf_hash_remove(dmu_buf_impl_t *db) 186 { 187 dbuf_hash_table_t *h = &dbuf_hash_table; 188 uint64_t hv = DBUF_HASH(db->db_objset, db->db.db_object, 189 db->db_level, db->db_blkid); 190 uint64_t idx = hv & h->hash_table_mask; 191 dmu_buf_impl_t *dbf, **dbp; 192 193 /* 194 * We musn't hold db_mtx to maintin lock ordering: 195 * DBUF_HASH_MUTEX > db_mtx. 196 */ 197 ASSERT(refcount_is_zero(&db->db_holds)); 198 ASSERT(db->db_state == DB_EVICTING); 199 ASSERT(!MUTEX_HELD(&db->db_mtx)); 200 201 mutex_enter(DBUF_HASH_MUTEX(h, idx)); 202 dbp = &h->hash_table[idx]; 203 while ((dbf = *dbp) != db) { 204 dbp = &dbf->db_hash_next; 205 ASSERT(dbf != NULL); 206 } 207 *dbp = db->db_hash_next; 208 db->db_hash_next = NULL; 209 mutex_exit(DBUF_HASH_MUTEX(h, idx)); 210 atomic_add_64(&dbuf_hash_count, -1); 211 } 212 213 static arc_evict_func_t dbuf_do_evict; 214 215 static void 216 dbuf_evict_user(dmu_buf_impl_t *db) 217 { 218 ASSERT(MUTEX_HELD(&db->db_mtx)); 219 220 if (db->db_level != 0 || db->db_evict_func == NULL) 221 return; 222 223 if (db->db_user_data_ptr_ptr) 224 *db->db_user_data_ptr_ptr = db->db.db_data; 225 db->db_evict_func(&db->db, db->db_user_ptr); 226 db->db_user_ptr = NULL; 227 db->db_user_data_ptr_ptr = NULL; 228 db->db_evict_func = NULL; 229 } 230 231 boolean_t 232 dbuf_is_metadata(dmu_buf_impl_t *db) 233 { 234 if (db->db_level > 0) { 235 return (B_TRUE); 236 } else { 237 boolean_t is_metadata; 238 239 DB_DNODE_ENTER(db); 240 is_metadata = DMU_OT_IS_METADATA(DB_DNODE(db)->dn_type); 241 DB_DNODE_EXIT(db); 242 243 return (is_metadata); 244 } 245 } 246 247 void 248 dbuf_evict(dmu_buf_impl_t *db) 249 { 250 ASSERT(MUTEX_HELD(&db->db_mtx)); 251 ASSERT(db->db_buf == NULL); 252 ASSERT(db->db_data_pending == NULL); 253 254 dbuf_clear(db); 255 dbuf_destroy(db); 256 } 257 258 void 259 dbuf_init(void) 260 { 261 uint64_t hsize = 1ULL << 16; 262 dbuf_hash_table_t *h = &dbuf_hash_table; 263 int i; 264 265 /* 266 * The hash table is big enough to fill all of physical memory 267 * with an average 4K block size. The table will take up 268 * totalmem*sizeof(void*)/4K (i.e. 2MB/GB with 8-byte pointers). 269 */ 270 while (hsize * 4096 < physmem * PAGESIZE) 271 hsize <<= 1; 272 273 retry: 274 h->hash_table_mask = hsize - 1; 275 h->hash_table = kmem_zalloc(hsize * sizeof (void *), KM_NOSLEEP); 276 if (h->hash_table == NULL) { 277 /* XXX - we should really return an error instead of assert */ 278 ASSERT(hsize > (1ULL << 10)); 279 hsize >>= 1; 280 goto retry; 281 } 282 283 dbuf_cache = kmem_cache_create("dmu_buf_impl_t", 284 sizeof (dmu_buf_impl_t), 285 0, dbuf_cons, dbuf_dest, NULL, NULL, NULL, 0); 286 287 for (i = 0; i < DBUF_MUTEXES; i++) 288 mutex_init(&h->hash_mutexes[i], NULL, MUTEX_DEFAULT, NULL); 289 } 290 291 void 292 dbuf_fini(void) 293 { 294 dbuf_hash_table_t *h = &dbuf_hash_table; 295 int i; 296 297 for (i = 0; i < DBUF_MUTEXES; i++) 298 mutex_destroy(&h->hash_mutexes[i]); 299 kmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *)); 300 kmem_cache_destroy(dbuf_cache); 301 } 302 303 /* 304 * Other stuff. 305 */ 306 307 #ifdef ZFS_DEBUG 308 static void 309 dbuf_verify(dmu_buf_impl_t *db) 310 { 311 dnode_t *dn; 312 dbuf_dirty_record_t *dr; 313 314 ASSERT(MUTEX_HELD(&db->db_mtx)); 315 316 if (!(zfs_flags & ZFS_DEBUG_DBUF_VERIFY)) 317 return; 318 319 ASSERT(db->db_objset != NULL); 320 DB_DNODE_ENTER(db); 321 dn = DB_DNODE(db); 322 if (dn == NULL) { 323 ASSERT(db->db_parent == NULL); 324 ASSERT(db->db_blkptr == NULL); 325 } else { 326 ASSERT3U(db->db.db_object, ==, dn->dn_object); 327 ASSERT3P(db->db_objset, ==, dn->dn_objset); 328 ASSERT3U(db->db_level, <, dn->dn_nlevels); 329 ASSERT(db->db_blkid == DMU_BONUS_BLKID || 330 db->db_blkid == DMU_SPILL_BLKID || 331 !list_is_empty(&dn->dn_dbufs)); 332 } 333 if (db->db_blkid == DMU_BONUS_BLKID) { 334 ASSERT(dn != NULL); 335 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen); 336 ASSERT3U(db->db.db_offset, ==, DMU_BONUS_BLKID); 337 } else if (db->db_blkid == DMU_SPILL_BLKID) { 338 ASSERT(dn != NULL); 339 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen); 340 ASSERT0(db->db.db_offset); 341 } else { 342 ASSERT3U(db->db.db_offset, ==, db->db_blkid * db->db.db_size); 343 } 344 345 for (dr = db->db_data_pending; dr != NULL; dr = dr->dr_next) 346 ASSERT(dr->dr_dbuf == db); 347 348 for (dr = db->db_last_dirty; dr != NULL; dr = dr->dr_next) 349 ASSERT(dr->dr_dbuf == db); 350 351 /* 352 * We can't assert that db_size matches dn_datablksz because it 353 * can be momentarily different when another thread is doing 354 * dnode_set_blksz(). 355 */ 356 if (db->db_level == 0 && db->db.db_object == DMU_META_DNODE_OBJECT) { 357 dr = db->db_data_pending; 358 /* 359 * It should only be modified in syncing context, so 360 * make sure we only have one copy of the data. 361 */ 362 ASSERT(dr == NULL || dr->dt.dl.dr_data == db->db_buf); 363 } 364 365 /* verify db->db_blkptr */ 366 if (db->db_blkptr) { 367 if (db->db_parent == dn->dn_dbuf) { 368 /* db is pointed to by the dnode */ 369 /* ASSERT3U(db->db_blkid, <, dn->dn_nblkptr); */ 370 if (DMU_OBJECT_IS_SPECIAL(db->db.db_object)) 371 ASSERT(db->db_parent == NULL); 372 else 373 ASSERT(db->db_parent != NULL); 374 if (db->db_blkid != DMU_SPILL_BLKID) 375 ASSERT3P(db->db_blkptr, ==, 376 &dn->dn_phys->dn_blkptr[db->db_blkid]); 377 } else { 378 /* db is pointed to by an indirect block */ 379 int epb = db->db_parent->db.db_size >> SPA_BLKPTRSHIFT; 380 ASSERT3U(db->db_parent->db_level, ==, db->db_level+1); 381 ASSERT3U(db->db_parent->db.db_object, ==, 382 db->db.db_object); 383 /* 384 * dnode_grow_indblksz() can make this fail if we don't 385 * have the struct_rwlock. XXX indblksz no longer 386 * grows. safe to do this now? 387 */ 388 if (RW_WRITE_HELD(&dn->dn_struct_rwlock)) { 389 ASSERT3P(db->db_blkptr, ==, 390 ((blkptr_t *)db->db_parent->db.db_data + 391 db->db_blkid % epb)); 392 } 393 } 394 } 395 if ((db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr)) && 396 (db->db_buf == NULL || db->db_buf->b_data) && 397 db->db.db_data && db->db_blkid != DMU_BONUS_BLKID && 398 db->db_state != DB_FILL && !dn->dn_free_txg) { 399 /* 400 * If the blkptr isn't set but they have nonzero data, 401 * it had better be dirty, otherwise we'll lose that 402 * data when we evict this buffer. 403 */ 404 if (db->db_dirtycnt == 0) { 405 uint64_t *buf = db->db.db_data; 406 int i; 407 408 for (i = 0; i < db->db.db_size >> 3; i++) { 409 ASSERT(buf[i] == 0); 410 } 411 } 412 } 413 DB_DNODE_EXIT(db); 414 } 415 #endif 416 417 static void 418 dbuf_update_data(dmu_buf_impl_t *db) 419 { 420 ASSERT(MUTEX_HELD(&db->db_mtx)); 421 if (db->db_level == 0 && db->db_user_data_ptr_ptr) { 422 ASSERT(!refcount_is_zero(&db->db_holds)); 423 *db->db_user_data_ptr_ptr = db->db.db_data; 424 } 425 } 426 427 static void 428 dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf) 429 { 430 ASSERT(MUTEX_HELD(&db->db_mtx)); 431 ASSERT(db->db_buf == NULL || !arc_has_callback(db->db_buf)); 432 db->db_buf = buf; 433 if (buf != NULL) { 434 ASSERT(buf->b_data != NULL); 435 db->db.db_data = buf->b_data; 436 if (!arc_released(buf)) 437 arc_set_callback(buf, dbuf_do_evict, db); 438 dbuf_update_data(db); 439 } else { 440 dbuf_evict_user(db); 441 db->db.db_data = NULL; 442 if (db->db_state != DB_NOFILL) 443 db->db_state = DB_UNCACHED; 444 } 445 } 446 447 /* 448 * Loan out an arc_buf for read. Return the loaned arc_buf. 449 */ 450 arc_buf_t * 451 dbuf_loan_arcbuf(dmu_buf_impl_t *db) 452 { 453 arc_buf_t *abuf; 454 455 mutex_enter(&db->db_mtx); 456 if (arc_released(db->db_buf) || refcount_count(&db->db_holds) > 1) { 457 int blksz = db->db.db_size; 458 spa_t *spa = db->db_objset->os_spa; 459 460 mutex_exit(&db->db_mtx); 461 abuf = arc_loan_buf(spa, blksz); 462 bcopy(db->db.db_data, abuf->b_data, blksz); 463 } else { 464 abuf = db->db_buf; 465 arc_loan_inuse_buf(abuf, db); 466 dbuf_set_data(db, NULL); 467 mutex_exit(&db->db_mtx); 468 } 469 return (abuf); 470 } 471 472 uint64_t 473 dbuf_whichblock(dnode_t *dn, uint64_t offset) 474 { 475 if (dn->dn_datablkshift) { 476 return (offset >> dn->dn_datablkshift); 477 } else { 478 ASSERT3U(offset, <, dn->dn_datablksz); 479 return (0); 480 } 481 } 482 483 static void 484 dbuf_read_done(zio_t *zio, arc_buf_t *buf, void *vdb) 485 { 486 dmu_buf_impl_t *db = vdb; 487 488 mutex_enter(&db->db_mtx); 489 ASSERT3U(db->db_state, ==, DB_READ); 490 /* 491 * All reads are synchronous, so we must have a hold on the dbuf 492 */ 493 ASSERT(refcount_count(&db->db_holds) > 0); 494 ASSERT(db->db_buf == NULL); 495 ASSERT(db->db.db_data == NULL); 496 if (db->db_level == 0 && db->db_freed_in_flight) { 497 /* we were freed in flight; disregard any error */ 498 arc_release(buf, db); 499 bzero(buf->b_data, db->db.db_size); 500 arc_buf_freeze(buf); 501 db->db_freed_in_flight = FALSE; 502 dbuf_set_data(db, buf); 503 db->db_state = DB_CACHED; 504 } else if (zio == NULL || zio->io_error == 0) { 505 dbuf_set_data(db, buf); 506 db->db_state = DB_CACHED; 507 } else { 508 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 509 ASSERT3P(db->db_buf, ==, NULL); 510 VERIFY(arc_buf_remove_ref(buf, db)); 511 db->db_state = DB_UNCACHED; 512 } 513 cv_broadcast(&db->db_changed); 514 dbuf_rele_and_unlock(db, NULL); 515 } 516 517 static void 518 dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t *flags) 519 { 520 dnode_t *dn; 521 zbookmark_t zb; 522 uint32_t aflags = ARC_NOWAIT; 523 524 DB_DNODE_ENTER(db); 525 dn = DB_DNODE(db); 526 ASSERT(!refcount_is_zero(&db->db_holds)); 527 /* We need the struct_rwlock to prevent db_blkptr from changing. */ 528 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 529 ASSERT(MUTEX_HELD(&db->db_mtx)); 530 ASSERT(db->db_state == DB_UNCACHED); 531 ASSERT(db->db_buf == NULL); 532 533 if (db->db_blkid == DMU_BONUS_BLKID) { 534 int bonuslen = MIN(dn->dn_bonuslen, dn->dn_phys->dn_bonuslen); 535 536 ASSERT3U(bonuslen, <=, db->db.db_size); 537 db->db.db_data = zio_buf_alloc(DN_MAX_BONUSLEN); 538 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER); 539 if (bonuslen < DN_MAX_BONUSLEN) 540 bzero(db->db.db_data, DN_MAX_BONUSLEN); 541 if (bonuslen) 542 bcopy(DN_BONUS(dn->dn_phys), db->db.db_data, bonuslen); 543 DB_DNODE_EXIT(db); 544 dbuf_update_data(db); 545 db->db_state = DB_CACHED; 546 mutex_exit(&db->db_mtx); 547 return; 548 } 549 550 /* 551 * Recheck BP_IS_HOLE() after dnode_block_freed() in case dnode_sync() 552 * processes the delete record and clears the bp while we are waiting 553 * for the dn_mtx (resulting in a "no" from block_freed). 554 */ 555 if (db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr) || 556 (db->db_level == 0 && (dnode_block_freed(dn, db->db_blkid) || 557 BP_IS_HOLE(db->db_blkptr)))) { 558 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 559 560 DB_DNODE_EXIT(db); 561 dbuf_set_data(db, arc_buf_alloc(db->db_objset->os_spa, 562 db->db.db_size, db, type)); 563 bzero(db->db.db_data, db->db.db_size); 564 db->db_state = DB_CACHED; 565 *flags |= DB_RF_CACHED; 566 mutex_exit(&db->db_mtx); 567 return; 568 } 569 570 DB_DNODE_EXIT(db); 571 572 db->db_state = DB_READ; 573 mutex_exit(&db->db_mtx); 574 575 if (DBUF_IS_L2CACHEABLE(db)) 576 aflags |= ARC_L2CACHE; 577 if (DBUF_IS_L2COMPRESSIBLE(db)) 578 aflags |= ARC_L2COMPRESS; 579 580 SET_BOOKMARK(&zb, db->db_objset->os_dsl_dataset ? 581 db->db_objset->os_dsl_dataset->ds_object : DMU_META_OBJSET, 582 db->db.db_object, db->db_level, db->db_blkid); 583 584 dbuf_add_ref(db, NULL); 585 586 (void) arc_read(zio, db->db_objset->os_spa, db->db_blkptr, 587 dbuf_read_done, db, ZIO_PRIORITY_SYNC_READ, 588 (*flags & DB_RF_CANFAIL) ? ZIO_FLAG_CANFAIL : ZIO_FLAG_MUSTSUCCEED, 589 &aflags, &zb); 590 if (aflags & ARC_CACHED) 591 *flags |= DB_RF_CACHED; 592 } 593 594 int 595 dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags) 596 { 597 int err = 0; 598 boolean_t havepzio = (zio != NULL); 599 boolean_t prefetch; 600 dnode_t *dn; 601 602 /* 603 * We don't have to hold the mutex to check db_state because it 604 * can't be freed while we have a hold on the buffer. 605 */ 606 ASSERT(!refcount_is_zero(&db->db_holds)); 607 608 if (db->db_state == DB_NOFILL) 609 return (SET_ERROR(EIO)); 610 611 DB_DNODE_ENTER(db); 612 dn = DB_DNODE(db); 613 if ((flags & DB_RF_HAVESTRUCT) == 0) 614 rw_enter(&dn->dn_struct_rwlock, RW_READER); 615 616 prefetch = db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID && 617 (flags & DB_RF_NOPREFETCH) == 0 && dn != NULL && 618 DBUF_IS_CACHEABLE(db); 619 620 mutex_enter(&db->db_mtx); 621 if (db->db_state == DB_CACHED) { 622 mutex_exit(&db->db_mtx); 623 if (prefetch) 624 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset, 625 db->db.db_size, TRUE); 626 if ((flags & DB_RF_HAVESTRUCT) == 0) 627 rw_exit(&dn->dn_struct_rwlock); 628 DB_DNODE_EXIT(db); 629 } else if (db->db_state == DB_UNCACHED) { 630 spa_t *spa = dn->dn_objset->os_spa; 631 632 if (zio == NULL) 633 zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL); 634 dbuf_read_impl(db, zio, &flags); 635 636 /* dbuf_read_impl has dropped db_mtx for us */ 637 638 if (prefetch) 639 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset, 640 db->db.db_size, flags & DB_RF_CACHED); 641 642 if ((flags & DB_RF_HAVESTRUCT) == 0) 643 rw_exit(&dn->dn_struct_rwlock); 644 DB_DNODE_EXIT(db); 645 646 if (!havepzio) 647 err = zio_wait(zio); 648 } else { 649 /* 650 * Another reader came in while the dbuf was in flight 651 * between UNCACHED and CACHED. Either a writer will finish 652 * writing the buffer (sending the dbuf to CACHED) or the 653 * first reader's request will reach the read_done callback 654 * and send the dbuf to CACHED. Otherwise, a failure 655 * occurred and the dbuf went to UNCACHED. 656 */ 657 mutex_exit(&db->db_mtx); 658 if (prefetch) 659 dmu_zfetch(&dn->dn_zfetch, db->db.db_offset, 660 db->db.db_size, TRUE); 661 if ((flags & DB_RF_HAVESTRUCT) == 0) 662 rw_exit(&dn->dn_struct_rwlock); 663 DB_DNODE_EXIT(db); 664 665 /* Skip the wait per the caller's request. */ 666 mutex_enter(&db->db_mtx); 667 if ((flags & DB_RF_NEVERWAIT) == 0) { 668 while (db->db_state == DB_READ || 669 db->db_state == DB_FILL) { 670 ASSERT(db->db_state == DB_READ || 671 (flags & DB_RF_HAVESTRUCT) == 0); 672 cv_wait(&db->db_changed, &db->db_mtx); 673 } 674 if (db->db_state == DB_UNCACHED) 675 err = SET_ERROR(EIO); 676 } 677 mutex_exit(&db->db_mtx); 678 } 679 680 ASSERT(err || havepzio || db->db_state == DB_CACHED); 681 return (err); 682 } 683 684 static void 685 dbuf_noread(dmu_buf_impl_t *db) 686 { 687 ASSERT(!refcount_is_zero(&db->db_holds)); 688 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 689 mutex_enter(&db->db_mtx); 690 while (db->db_state == DB_READ || db->db_state == DB_FILL) 691 cv_wait(&db->db_changed, &db->db_mtx); 692 if (db->db_state == DB_UNCACHED) { 693 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 694 spa_t *spa = db->db_objset->os_spa; 695 696 ASSERT(db->db_buf == NULL); 697 ASSERT(db->db.db_data == NULL); 698 dbuf_set_data(db, arc_buf_alloc(spa, db->db.db_size, db, type)); 699 db->db_state = DB_FILL; 700 } else if (db->db_state == DB_NOFILL) { 701 dbuf_set_data(db, NULL); 702 } else { 703 ASSERT3U(db->db_state, ==, DB_CACHED); 704 } 705 mutex_exit(&db->db_mtx); 706 } 707 708 /* 709 * This is our just-in-time copy function. It makes a copy of 710 * buffers, that have been modified in a previous transaction 711 * group, before we modify them in the current active group. 712 * 713 * This function is used in two places: when we are dirtying a 714 * buffer for the first time in a txg, and when we are freeing 715 * a range in a dnode that includes this buffer. 716 * 717 * Note that when we are called from dbuf_free_range() we do 718 * not put a hold on the buffer, we just traverse the active 719 * dbuf list for the dnode. 720 */ 721 static void 722 dbuf_fix_old_data(dmu_buf_impl_t *db, uint64_t txg) 723 { 724 dbuf_dirty_record_t *dr = db->db_last_dirty; 725 726 ASSERT(MUTEX_HELD(&db->db_mtx)); 727 ASSERT(db->db.db_data != NULL); 728 ASSERT(db->db_level == 0); 729 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT); 730 731 if (dr == NULL || 732 (dr->dt.dl.dr_data != 733 ((db->db_blkid == DMU_BONUS_BLKID) ? db->db.db_data : db->db_buf))) 734 return; 735 736 /* 737 * If the last dirty record for this dbuf has not yet synced 738 * and its referencing the dbuf data, either: 739 * reset the reference to point to a new copy, 740 * or (if there a no active holders) 741 * just null out the current db_data pointer. 742 */ 743 ASSERT(dr->dr_txg >= txg - 2); 744 if (db->db_blkid == DMU_BONUS_BLKID) { 745 /* Note that the data bufs here are zio_bufs */ 746 dr->dt.dl.dr_data = zio_buf_alloc(DN_MAX_BONUSLEN); 747 arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER); 748 bcopy(db->db.db_data, dr->dt.dl.dr_data, DN_MAX_BONUSLEN); 749 } else if (refcount_count(&db->db_holds) > db->db_dirtycnt) { 750 int size = db->db.db_size; 751 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 752 spa_t *spa = db->db_objset->os_spa; 753 754 dr->dt.dl.dr_data = arc_buf_alloc(spa, size, db, type); 755 bcopy(db->db.db_data, dr->dt.dl.dr_data->b_data, size); 756 } else { 757 dbuf_set_data(db, NULL); 758 } 759 } 760 761 void 762 dbuf_unoverride(dbuf_dirty_record_t *dr) 763 { 764 dmu_buf_impl_t *db = dr->dr_dbuf; 765 blkptr_t *bp = &dr->dt.dl.dr_overridden_by; 766 uint64_t txg = dr->dr_txg; 767 768 ASSERT(MUTEX_HELD(&db->db_mtx)); 769 ASSERT(dr->dt.dl.dr_override_state != DR_IN_DMU_SYNC); 770 ASSERT(db->db_level == 0); 771 772 if (db->db_blkid == DMU_BONUS_BLKID || 773 dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN) 774 return; 775 776 ASSERT(db->db_data_pending != dr); 777 778 /* free this block */ 779 if (!BP_IS_HOLE(bp) && !dr->dt.dl.dr_nopwrite) 780 zio_free(db->db_objset->os_spa, txg, bp); 781 782 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN; 783 dr->dt.dl.dr_nopwrite = B_FALSE; 784 785 /* 786 * Release the already-written buffer, so we leave it in 787 * a consistent dirty state. Note that all callers are 788 * modifying the buffer, so they will immediately do 789 * another (redundant) arc_release(). Therefore, leave 790 * the buf thawed to save the effort of freezing & 791 * immediately re-thawing it. 792 */ 793 arc_release(dr->dt.dl.dr_data, db); 794 } 795 796 /* 797 * Evict (if its unreferenced) or clear (if its referenced) any level-0 798 * data blocks in the free range, so that any future readers will find 799 * empty blocks. 800 * 801 * This is a no-op if the dataset is in the middle of an incremental 802 * receive; see comment below for details. 803 */ 804 void 805 dbuf_free_range(dnode_t *dn, uint64_t start, uint64_t end, dmu_tx_t *tx) 806 { 807 dmu_buf_impl_t *db, *db_next; 808 uint64_t txg = tx->tx_txg; 809 810 if (end > dn->dn_maxblkid && (end != DMU_SPILL_BLKID)) 811 end = dn->dn_maxblkid; 812 dprintf_dnode(dn, "start=%llu end=%llu\n", start, end); 813 814 mutex_enter(&dn->dn_dbufs_mtx); 815 if (start >= dn->dn_unlisted_l0_blkid * dn->dn_datablksz) { 816 /* There can't be any dbufs in this range; no need to search. */ 817 mutex_exit(&dn->dn_dbufs_mtx); 818 return; 819 } else if (dmu_objset_is_receiving(dn->dn_objset)) { 820 /* 821 * If we are receiving, we expect there to be no dbufs in 822 * the range to be freed, because receive modifies each 823 * block at most once, and in offset order. If this is 824 * not the case, it can lead to performance problems, 825 * so note that we unexpectedly took the slow path. 826 */ 827 atomic_inc_64(&zfs_free_range_recv_miss); 828 } 829 830 for (db = list_head(&dn->dn_dbufs); db != NULL; db = db_next) { 831 db_next = list_next(&dn->dn_dbufs, db); 832 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 833 834 if (db->db_level != 0) 835 continue; 836 if (db->db_blkid < start || db->db_blkid > end) 837 continue; 838 839 /* found a level 0 buffer in the range */ 840 mutex_enter(&db->db_mtx); 841 if (dbuf_undirty(db, tx)) { 842 /* mutex has been dropped and dbuf destroyed */ 843 continue; 844 } 845 846 if (db->db_state == DB_UNCACHED || 847 db->db_state == DB_NOFILL || 848 db->db_state == DB_EVICTING) { 849 ASSERT(db->db.db_data == NULL); 850 mutex_exit(&db->db_mtx); 851 continue; 852 } 853 if (db->db_state == DB_READ || db->db_state == DB_FILL) { 854 /* will be handled in dbuf_read_done or dbuf_rele */ 855 db->db_freed_in_flight = TRUE; 856 mutex_exit(&db->db_mtx); 857 continue; 858 } 859 if (refcount_count(&db->db_holds) == 0) { 860 ASSERT(db->db_buf); 861 dbuf_clear(db); 862 continue; 863 } 864 /* The dbuf is referenced */ 865 866 if (db->db_last_dirty != NULL) { 867 dbuf_dirty_record_t *dr = db->db_last_dirty; 868 869 if (dr->dr_txg == txg) { 870 /* 871 * This buffer is "in-use", re-adjust the file 872 * size to reflect that this buffer may 873 * contain new data when we sync. 874 */ 875 if (db->db_blkid != DMU_SPILL_BLKID && 876 db->db_blkid > dn->dn_maxblkid) 877 dn->dn_maxblkid = db->db_blkid; 878 dbuf_unoverride(dr); 879 } else { 880 /* 881 * This dbuf is not dirty in the open context. 882 * Either uncache it (if its not referenced in 883 * the open context) or reset its contents to 884 * empty. 885 */ 886 dbuf_fix_old_data(db, txg); 887 } 888 } 889 /* clear the contents if its cached */ 890 if (db->db_state == DB_CACHED) { 891 ASSERT(db->db.db_data != NULL); 892 arc_release(db->db_buf, db); 893 bzero(db->db.db_data, db->db.db_size); 894 arc_buf_freeze(db->db_buf); 895 } 896 897 mutex_exit(&db->db_mtx); 898 } 899 mutex_exit(&dn->dn_dbufs_mtx); 900 } 901 902 static int 903 dbuf_block_freeable(dmu_buf_impl_t *db) 904 { 905 dsl_dataset_t *ds = db->db_objset->os_dsl_dataset; 906 uint64_t birth_txg = 0; 907 908 /* 909 * We don't need any locking to protect db_blkptr: 910 * If it's syncing, then db_last_dirty will be set 911 * so we'll ignore db_blkptr. 912 * 913 * This logic ensures that only block births for 914 * filled blocks are considered. 915 */ 916 ASSERT(MUTEX_HELD(&db->db_mtx)); 917 if (db->db_last_dirty && (db->db_blkptr == NULL || 918 !BP_IS_HOLE(db->db_blkptr))) { 919 birth_txg = db->db_last_dirty->dr_txg; 920 } else if (db->db_blkptr != NULL && !BP_IS_HOLE(db->db_blkptr)) { 921 birth_txg = db->db_blkptr->blk_birth; 922 } 923 924 /* 925 * If this block don't exist or is in a snapshot, it can't be freed. 926 * Don't pass the bp to dsl_dataset_block_freeable() since we 927 * are holding the db_mtx lock and might deadlock if we are 928 * prefetching a dedup-ed block. 929 */ 930 if (birth_txg != 0) 931 return (ds == NULL || 932 dsl_dataset_block_freeable(ds, NULL, birth_txg)); 933 else 934 return (B_FALSE); 935 } 936 937 void 938 dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx) 939 { 940 arc_buf_t *buf, *obuf; 941 int osize = db->db.db_size; 942 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 943 dnode_t *dn; 944 945 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 946 947 DB_DNODE_ENTER(db); 948 dn = DB_DNODE(db); 949 950 /* XXX does *this* func really need the lock? */ 951 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock)); 952 953 /* 954 * This call to dmu_buf_will_dirty() with the dn_struct_rwlock held 955 * is OK, because there can be no other references to the db 956 * when we are changing its size, so no concurrent DB_FILL can 957 * be happening. 958 */ 959 /* 960 * XXX we should be doing a dbuf_read, checking the return 961 * value and returning that up to our callers 962 */ 963 dmu_buf_will_dirty(&db->db, tx); 964 965 /* create the data buffer for the new block */ 966 buf = arc_buf_alloc(dn->dn_objset->os_spa, size, db, type); 967 968 /* copy old block data to the new block */ 969 obuf = db->db_buf; 970 bcopy(obuf->b_data, buf->b_data, MIN(osize, size)); 971 /* zero the remainder */ 972 if (size > osize) 973 bzero((uint8_t *)buf->b_data + osize, size - osize); 974 975 mutex_enter(&db->db_mtx); 976 dbuf_set_data(db, buf); 977 VERIFY(arc_buf_remove_ref(obuf, db)); 978 db->db.db_size = size; 979 980 if (db->db_level == 0) { 981 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg); 982 db->db_last_dirty->dt.dl.dr_data = buf; 983 } 984 mutex_exit(&db->db_mtx); 985 986 dnode_willuse_space(dn, size-osize, tx); 987 DB_DNODE_EXIT(db); 988 } 989 990 void 991 dbuf_release_bp(dmu_buf_impl_t *db) 992 { 993 objset_t *os = db->db_objset; 994 995 ASSERT(dsl_pool_sync_context(dmu_objset_pool(os))); 996 ASSERT(arc_released(os->os_phys_buf) || 997 list_link_active(&os->os_dsl_dataset->ds_synced_link)); 998 ASSERT(db->db_parent == NULL || arc_released(db->db_parent->db_buf)); 999 1000 (void) arc_release(db->db_buf, db); 1001 } 1002 1003 dbuf_dirty_record_t * 1004 dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx) 1005 { 1006 dnode_t *dn; 1007 objset_t *os; 1008 dbuf_dirty_record_t **drp, *dr; 1009 int drop_struct_lock = FALSE; 1010 boolean_t do_free_accounting = B_FALSE; 1011 int txgoff = tx->tx_txg & TXG_MASK; 1012 1013 ASSERT(tx->tx_txg != 0); 1014 ASSERT(!refcount_is_zero(&db->db_holds)); 1015 DMU_TX_DIRTY_BUF(tx, db); 1016 1017 DB_DNODE_ENTER(db); 1018 dn = DB_DNODE(db); 1019 /* 1020 * Shouldn't dirty a regular buffer in syncing context. Private 1021 * objects may be dirtied in syncing context, but only if they 1022 * were already pre-dirtied in open context. 1023 */ 1024 ASSERT(!dmu_tx_is_syncing(tx) || 1025 BP_IS_HOLE(dn->dn_objset->os_rootbp) || 1026 DMU_OBJECT_IS_SPECIAL(dn->dn_object) || 1027 dn->dn_objset->os_dsl_dataset == NULL); 1028 /* 1029 * We make this assert for private objects as well, but after we 1030 * check if we're already dirty. They are allowed to re-dirty 1031 * in syncing context. 1032 */ 1033 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT || 1034 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx == 1035 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN)); 1036 1037 mutex_enter(&db->db_mtx); 1038 /* 1039 * XXX make this true for indirects too? The problem is that 1040 * transactions created with dmu_tx_create_assigned() from 1041 * syncing context don't bother holding ahead. 1042 */ 1043 ASSERT(db->db_level != 0 || 1044 db->db_state == DB_CACHED || db->db_state == DB_FILL || 1045 db->db_state == DB_NOFILL); 1046 1047 mutex_enter(&dn->dn_mtx); 1048 /* 1049 * Don't set dirtyctx to SYNC if we're just modifying this as we 1050 * initialize the objset. 1051 */ 1052 if (dn->dn_dirtyctx == DN_UNDIRTIED && 1053 !BP_IS_HOLE(dn->dn_objset->os_rootbp)) { 1054 dn->dn_dirtyctx = 1055 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN); 1056 ASSERT(dn->dn_dirtyctx_firstset == NULL); 1057 dn->dn_dirtyctx_firstset = kmem_alloc(1, KM_SLEEP); 1058 } 1059 mutex_exit(&dn->dn_mtx); 1060 1061 if (db->db_blkid == DMU_SPILL_BLKID) 1062 dn->dn_have_spill = B_TRUE; 1063 1064 /* 1065 * If this buffer is already dirty, we're done. 1066 */ 1067 drp = &db->db_last_dirty; 1068 ASSERT(*drp == NULL || (*drp)->dr_txg <= tx->tx_txg || 1069 db->db.db_object == DMU_META_DNODE_OBJECT); 1070 while ((dr = *drp) != NULL && dr->dr_txg > tx->tx_txg) 1071 drp = &dr->dr_next; 1072 if (dr && dr->dr_txg == tx->tx_txg) { 1073 DB_DNODE_EXIT(db); 1074 1075 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID) { 1076 /* 1077 * If this buffer has already been written out, 1078 * we now need to reset its state. 1079 */ 1080 dbuf_unoverride(dr); 1081 if (db->db.db_object != DMU_META_DNODE_OBJECT && 1082 db->db_state != DB_NOFILL) 1083 arc_buf_thaw(db->db_buf); 1084 } 1085 mutex_exit(&db->db_mtx); 1086 return (dr); 1087 } 1088 1089 /* 1090 * Only valid if not already dirty. 1091 */ 1092 ASSERT(dn->dn_object == 0 || 1093 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx == 1094 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN)); 1095 1096 ASSERT3U(dn->dn_nlevels, >, db->db_level); 1097 ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) || 1098 dn->dn_phys->dn_nlevels > db->db_level || 1099 dn->dn_next_nlevels[txgoff] > db->db_level || 1100 dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level || 1101 dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level); 1102 1103 /* 1104 * We should only be dirtying in syncing context if it's the 1105 * mos or we're initializing the os or it's a special object. 1106 * However, we are allowed to dirty in syncing context provided 1107 * we already dirtied it in open context. Hence we must make 1108 * this assertion only if we're not already dirty. 1109 */ 1110 os = dn->dn_objset; 1111 ASSERT(!dmu_tx_is_syncing(tx) || DMU_OBJECT_IS_SPECIAL(dn->dn_object) || 1112 os->os_dsl_dataset == NULL || BP_IS_HOLE(os->os_rootbp)); 1113 ASSERT(db->db.db_size != 0); 1114 1115 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size); 1116 1117 if (db->db_blkid != DMU_BONUS_BLKID) { 1118 /* 1119 * Update the accounting. 1120 * Note: we delay "free accounting" until after we drop 1121 * the db_mtx. This keeps us from grabbing other locks 1122 * (and possibly deadlocking) in bp_get_dsize() while 1123 * also holding the db_mtx. 1124 */ 1125 dnode_willuse_space(dn, db->db.db_size, tx); 1126 do_free_accounting = dbuf_block_freeable(db); 1127 } 1128 1129 /* 1130 * If this buffer is dirty in an old transaction group we need 1131 * to make a copy of it so that the changes we make in this 1132 * transaction group won't leak out when we sync the older txg. 1133 */ 1134 dr = kmem_zalloc(sizeof (dbuf_dirty_record_t), KM_SLEEP); 1135 if (db->db_level == 0) { 1136 void *data_old = db->db_buf; 1137 1138 if (db->db_state != DB_NOFILL) { 1139 if (db->db_blkid == DMU_BONUS_BLKID) { 1140 dbuf_fix_old_data(db, tx->tx_txg); 1141 data_old = db->db.db_data; 1142 } else if (db->db.db_object != DMU_META_DNODE_OBJECT) { 1143 /* 1144 * Release the data buffer from the cache so 1145 * that we can modify it without impacting 1146 * possible other users of this cached data 1147 * block. Note that indirect blocks and 1148 * private objects are not released until the 1149 * syncing state (since they are only modified 1150 * then). 1151 */ 1152 arc_release(db->db_buf, db); 1153 dbuf_fix_old_data(db, tx->tx_txg); 1154 data_old = db->db_buf; 1155 } 1156 ASSERT(data_old != NULL); 1157 } 1158 dr->dt.dl.dr_data = data_old; 1159 } else { 1160 mutex_init(&dr->dt.di.dr_mtx, NULL, MUTEX_DEFAULT, NULL); 1161 list_create(&dr->dt.di.dr_children, 1162 sizeof (dbuf_dirty_record_t), 1163 offsetof(dbuf_dirty_record_t, dr_dirty_node)); 1164 } 1165 if (db->db_blkid != DMU_BONUS_BLKID && os->os_dsl_dataset != NULL) 1166 dr->dr_accounted = db->db.db_size; 1167 dr->dr_dbuf = db; 1168 dr->dr_txg = tx->tx_txg; 1169 dr->dr_next = *drp; 1170 *drp = dr; 1171 1172 /* 1173 * We could have been freed_in_flight between the dbuf_noread 1174 * and dbuf_dirty. We win, as though the dbuf_noread() had 1175 * happened after the free. 1176 */ 1177 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID && 1178 db->db_blkid != DMU_SPILL_BLKID) { 1179 mutex_enter(&dn->dn_mtx); 1180 dnode_clear_range(dn, db->db_blkid, 1, tx); 1181 mutex_exit(&dn->dn_mtx); 1182 db->db_freed_in_flight = FALSE; 1183 } 1184 1185 /* 1186 * This buffer is now part of this txg 1187 */ 1188 dbuf_add_ref(db, (void *)(uintptr_t)tx->tx_txg); 1189 db->db_dirtycnt += 1; 1190 ASSERT3U(db->db_dirtycnt, <=, 3); 1191 1192 mutex_exit(&db->db_mtx); 1193 1194 if (db->db_blkid == DMU_BONUS_BLKID || 1195 db->db_blkid == DMU_SPILL_BLKID) { 1196 mutex_enter(&dn->dn_mtx); 1197 ASSERT(!list_link_active(&dr->dr_dirty_node)); 1198 list_insert_tail(&dn->dn_dirty_records[txgoff], dr); 1199 mutex_exit(&dn->dn_mtx); 1200 dnode_setdirty(dn, tx); 1201 DB_DNODE_EXIT(db); 1202 return (dr); 1203 } else if (do_free_accounting) { 1204 blkptr_t *bp = db->db_blkptr; 1205 int64_t willfree = (bp && !BP_IS_HOLE(bp)) ? 1206 bp_get_dsize(os->os_spa, bp) : db->db.db_size; 1207 /* 1208 * This is only a guess -- if the dbuf is dirty 1209 * in a previous txg, we don't know how much 1210 * space it will use on disk yet. We should 1211 * really have the struct_rwlock to access 1212 * db_blkptr, but since this is just a guess, 1213 * it's OK if we get an odd answer. 1214 */ 1215 ddt_prefetch(os->os_spa, bp); 1216 dnode_willuse_space(dn, -willfree, tx); 1217 } 1218 1219 if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) { 1220 rw_enter(&dn->dn_struct_rwlock, RW_READER); 1221 drop_struct_lock = TRUE; 1222 } 1223 1224 if (db->db_level == 0) { 1225 dnode_new_blkid(dn, db->db_blkid, tx, drop_struct_lock); 1226 ASSERT(dn->dn_maxblkid >= db->db_blkid); 1227 } 1228 1229 if (db->db_level+1 < dn->dn_nlevels) { 1230 dmu_buf_impl_t *parent = db->db_parent; 1231 dbuf_dirty_record_t *di; 1232 int parent_held = FALSE; 1233 1234 if (db->db_parent == NULL || db->db_parent == dn->dn_dbuf) { 1235 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT; 1236 1237 parent = dbuf_hold_level(dn, db->db_level+1, 1238 db->db_blkid >> epbs, FTAG); 1239 ASSERT(parent != NULL); 1240 parent_held = TRUE; 1241 } 1242 if (drop_struct_lock) 1243 rw_exit(&dn->dn_struct_rwlock); 1244 ASSERT3U(db->db_level+1, ==, parent->db_level); 1245 di = dbuf_dirty(parent, tx); 1246 if (parent_held) 1247 dbuf_rele(parent, FTAG); 1248 1249 mutex_enter(&db->db_mtx); 1250 /* 1251 * Since we've dropped the mutex, it's possible that 1252 * dbuf_undirty() might have changed this out from under us. 1253 */ 1254 if (db->db_last_dirty == dr || 1255 dn->dn_object == DMU_META_DNODE_OBJECT) { 1256 mutex_enter(&di->dt.di.dr_mtx); 1257 ASSERT3U(di->dr_txg, ==, tx->tx_txg); 1258 ASSERT(!list_link_active(&dr->dr_dirty_node)); 1259 list_insert_tail(&di->dt.di.dr_children, dr); 1260 mutex_exit(&di->dt.di.dr_mtx); 1261 dr->dr_parent = di; 1262 } 1263 mutex_exit(&db->db_mtx); 1264 } else { 1265 ASSERT(db->db_level+1 == dn->dn_nlevels); 1266 ASSERT(db->db_blkid < dn->dn_nblkptr); 1267 ASSERT(db->db_parent == NULL || db->db_parent == dn->dn_dbuf); 1268 mutex_enter(&dn->dn_mtx); 1269 ASSERT(!list_link_active(&dr->dr_dirty_node)); 1270 list_insert_tail(&dn->dn_dirty_records[txgoff], dr); 1271 mutex_exit(&dn->dn_mtx); 1272 if (drop_struct_lock) 1273 rw_exit(&dn->dn_struct_rwlock); 1274 } 1275 1276 dnode_setdirty(dn, tx); 1277 DB_DNODE_EXIT(db); 1278 return (dr); 1279 } 1280 1281 /* 1282 * Undirty a buffer in the transaction group referenced by the given 1283 * transaction. Return whether this evicted the dbuf. 1284 */ 1285 static boolean_t 1286 dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx) 1287 { 1288 dnode_t *dn; 1289 uint64_t txg = tx->tx_txg; 1290 dbuf_dirty_record_t *dr, **drp; 1291 1292 ASSERT(txg != 0); 1293 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1294 ASSERT0(db->db_level); 1295 ASSERT(MUTEX_HELD(&db->db_mtx)); 1296 1297 /* 1298 * If this buffer is not dirty, we're done. 1299 */ 1300 for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next) 1301 if (dr->dr_txg <= txg) 1302 break; 1303 if (dr == NULL || dr->dr_txg < txg) 1304 return (B_FALSE); 1305 ASSERT(dr->dr_txg == txg); 1306 ASSERT(dr->dr_dbuf == db); 1307 1308 DB_DNODE_ENTER(db); 1309 dn = DB_DNODE(db); 1310 1311 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size); 1312 1313 ASSERT(db->db.db_size != 0); 1314 1315 /* 1316 * Any space we accounted for in dp_dirty_* will be cleaned up by 1317 * dsl_pool_sync(). This is relatively rare so the discrepancy 1318 * is not a big deal. 1319 */ 1320 1321 *drp = dr->dr_next; 1322 1323 /* 1324 * Note that there are three places in dbuf_dirty() 1325 * where this dirty record may be put on a list. 1326 * Make sure to do a list_remove corresponding to 1327 * every one of those list_insert calls. 1328 */ 1329 if (dr->dr_parent) { 1330 mutex_enter(&dr->dr_parent->dt.di.dr_mtx); 1331 list_remove(&dr->dr_parent->dt.di.dr_children, dr); 1332 mutex_exit(&dr->dr_parent->dt.di.dr_mtx); 1333 } else if (db->db_blkid == DMU_SPILL_BLKID || 1334 db->db_level+1 == dn->dn_nlevels) { 1335 ASSERT(db->db_blkptr == NULL || db->db_parent == dn->dn_dbuf); 1336 mutex_enter(&dn->dn_mtx); 1337 list_remove(&dn->dn_dirty_records[txg & TXG_MASK], dr); 1338 mutex_exit(&dn->dn_mtx); 1339 } 1340 DB_DNODE_EXIT(db); 1341 1342 if (db->db_state != DB_NOFILL) { 1343 dbuf_unoverride(dr); 1344 1345 ASSERT(db->db_buf != NULL); 1346 ASSERT(dr->dt.dl.dr_data != NULL); 1347 if (dr->dt.dl.dr_data != db->db_buf) 1348 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data, db)); 1349 } 1350 kmem_free(dr, sizeof (dbuf_dirty_record_t)); 1351 1352 ASSERT(db->db_dirtycnt > 0); 1353 db->db_dirtycnt -= 1; 1354 1355 if (refcount_remove(&db->db_holds, (void *)(uintptr_t)txg) == 0) { 1356 arc_buf_t *buf = db->db_buf; 1357 1358 ASSERT(db->db_state == DB_NOFILL || arc_released(buf)); 1359 dbuf_set_data(db, NULL); 1360 VERIFY(arc_buf_remove_ref(buf, db)); 1361 dbuf_evict(db); 1362 return (B_TRUE); 1363 } 1364 1365 return (B_FALSE); 1366 } 1367 1368 void 1369 dmu_buf_will_dirty(dmu_buf_t *db_fake, dmu_tx_t *tx) 1370 { 1371 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 1372 int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH; 1373 1374 ASSERT(tx->tx_txg != 0); 1375 ASSERT(!refcount_is_zero(&db->db_holds)); 1376 1377 DB_DNODE_ENTER(db); 1378 if (RW_WRITE_HELD(&DB_DNODE(db)->dn_struct_rwlock)) 1379 rf |= DB_RF_HAVESTRUCT; 1380 DB_DNODE_EXIT(db); 1381 (void) dbuf_read(db, NULL, rf); 1382 (void) dbuf_dirty(db, tx); 1383 } 1384 1385 void 1386 dmu_buf_will_not_fill(dmu_buf_t *db_fake, dmu_tx_t *tx) 1387 { 1388 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 1389 1390 db->db_state = DB_NOFILL; 1391 1392 dmu_buf_will_fill(db_fake, tx); 1393 } 1394 1395 void 1396 dmu_buf_will_fill(dmu_buf_t *db_fake, dmu_tx_t *tx) 1397 { 1398 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 1399 1400 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1401 ASSERT(tx->tx_txg != 0); 1402 ASSERT(db->db_level == 0); 1403 ASSERT(!refcount_is_zero(&db->db_holds)); 1404 1405 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT || 1406 dmu_tx_private_ok(tx)); 1407 1408 dbuf_noread(db); 1409 (void) dbuf_dirty(db, tx); 1410 } 1411 1412 #pragma weak dmu_buf_fill_done = dbuf_fill_done 1413 /* ARGSUSED */ 1414 void 1415 dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx) 1416 { 1417 mutex_enter(&db->db_mtx); 1418 DBUF_VERIFY(db); 1419 1420 if (db->db_state == DB_FILL) { 1421 if (db->db_level == 0 && db->db_freed_in_flight) { 1422 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1423 /* we were freed while filling */ 1424 /* XXX dbuf_undirty? */ 1425 bzero(db->db.db_data, db->db.db_size); 1426 db->db_freed_in_flight = FALSE; 1427 } 1428 db->db_state = DB_CACHED; 1429 cv_broadcast(&db->db_changed); 1430 } 1431 mutex_exit(&db->db_mtx); 1432 } 1433 1434 /* 1435 * Directly assign a provided arc buf to a given dbuf if it's not referenced 1436 * by anybody except our caller. Otherwise copy arcbuf's contents to dbuf. 1437 */ 1438 void 1439 dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx) 1440 { 1441 ASSERT(!refcount_is_zero(&db->db_holds)); 1442 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 1443 ASSERT(db->db_level == 0); 1444 ASSERT(DBUF_GET_BUFC_TYPE(db) == ARC_BUFC_DATA); 1445 ASSERT(buf != NULL); 1446 ASSERT(arc_buf_size(buf) == db->db.db_size); 1447 ASSERT(tx->tx_txg != 0); 1448 1449 arc_return_buf(buf, db); 1450 ASSERT(arc_released(buf)); 1451 1452 mutex_enter(&db->db_mtx); 1453 1454 while (db->db_state == DB_READ || db->db_state == DB_FILL) 1455 cv_wait(&db->db_changed, &db->db_mtx); 1456 1457 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED); 1458 1459 if (db->db_state == DB_CACHED && 1460 refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) { 1461 mutex_exit(&db->db_mtx); 1462 (void) dbuf_dirty(db, tx); 1463 bcopy(buf->b_data, db->db.db_data, db->db.db_size); 1464 VERIFY(arc_buf_remove_ref(buf, db)); 1465 xuio_stat_wbuf_copied(); 1466 return; 1467 } 1468 1469 xuio_stat_wbuf_nocopy(); 1470 if (db->db_state == DB_CACHED) { 1471 dbuf_dirty_record_t *dr = db->db_last_dirty; 1472 1473 ASSERT(db->db_buf != NULL); 1474 if (dr != NULL && dr->dr_txg == tx->tx_txg) { 1475 ASSERT(dr->dt.dl.dr_data == db->db_buf); 1476 if (!arc_released(db->db_buf)) { 1477 ASSERT(dr->dt.dl.dr_override_state == 1478 DR_OVERRIDDEN); 1479 arc_release(db->db_buf, db); 1480 } 1481 dr->dt.dl.dr_data = buf; 1482 VERIFY(arc_buf_remove_ref(db->db_buf, db)); 1483 } else if (dr == NULL || dr->dt.dl.dr_data != db->db_buf) { 1484 arc_release(db->db_buf, db); 1485 VERIFY(arc_buf_remove_ref(db->db_buf, db)); 1486 } 1487 db->db_buf = NULL; 1488 } 1489 ASSERT(db->db_buf == NULL); 1490 dbuf_set_data(db, buf); 1491 db->db_state = DB_FILL; 1492 mutex_exit(&db->db_mtx); 1493 (void) dbuf_dirty(db, tx); 1494 dmu_buf_fill_done(&db->db, tx); 1495 } 1496 1497 /* 1498 * "Clear" the contents of this dbuf. This will mark the dbuf 1499 * EVICTING and clear *most* of its references. Unfortunately, 1500 * when we are not holding the dn_dbufs_mtx, we can't clear the 1501 * entry in the dn_dbufs list. We have to wait until dbuf_destroy() 1502 * in this case. For callers from the DMU we will usually see: 1503 * dbuf_clear()->arc_buf_evict()->dbuf_do_evict()->dbuf_destroy() 1504 * For the arc callback, we will usually see: 1505 * dbuf_do_evict()->dbuf_clear();dbuf_destroy() 1506 * Sometimes, though, we will get a mix of these two: 1507 * DMU: dbuf_clear()->arc_buf_evict() 1508 * ARC: dbuf_do_evict()->dbuf_destroy() 1509 */ 1510 void 1511 dbuf_clear(dmu_buf_impl_t *db) 1512 { 1513 dnode_t *dn; 1514 dmu_buf_impl_t *parent = db->db_parent; 1515 dmu_buf_impl_t *dndb; 1516 int dbuf_gone = FALSE; 1517 1518 ASSERT(MUTEX_HELD(&db->db_mtx)); 1519 ASSERT(refcount_is_zero(&db->db_holds)); 1520 1521 dbuf_evict_user(db); 1522 1523 if (db->db_state == DB_CACHED) { 1524 ASSERT(db->db.db_data != NULL); 1525 if (db->db_blkid == DMU_BONUS_BLKID) { 1526 zio_buf_free(db->db.db_data, DN_MAX_BONUSLEN); 1527 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER); 1528 } 1529 db->db.db_data = NULL; 1530 db->db_state = DB_UNCACHED; 1531 } 1532 1533 ASSERT(db->db_state == DB_UNCACHED || db->db_state == DB_NOFILL); 1534 ASSERT(db->db_data_pending == NULL); 1535 1536 db->db_state = DB_EVICTING; 1537 db->db_blkptr = NULL; 1538 1539 DB_DNODE_ENTER(db); 1540 dn = DB_DNODE(db); 1541 dndb = dn->dn_dbuf; 1542 if (db->db_blkid != DMU_BONUS_BLKID && MUTEX_HELD(&dn->dn_dbufs_mtx)) { 1543 list_remove(&dn->dn_dbufs, db); 1544 (void) atomic_dec_32_nv(&dn->dn_dbufs_count); 1545 membar_producer(); 1546 DB_DNODE_EXIT(db); 1547 /* 1548 * Decrementing the dbuf count means that the hold corresponding 1549 * to the removed dbuf is no longer discounted in dnode_move(), 1550 * so the dnode cannot be moved until after we release the hold. 1551 * The membar_producer() ensures visibility of the decremented 1552 * value in dnode_move(), since DB_DNODE_EXIT doesn't actually 1553 * release any lock. 1554 */ 1555 dnode_rele(dn, db); 1556 db->db_dnode_handle = NULL; 1557 } else { 1558 DB_DNODE_EXIT(db); 1559 } 1560 1561 if (db->db_buf) 1562 dbuf_gone = arc_buf_evict(db->db_buf); 1563 1564 if (!dbuf_gone) 1565 mutex_exit(&db->db_mtx); 1566 1567 /* 1568 * If this dbuf is referenced from an indirect dbuf, 1569 * decrement the ref count on the indirect dbuf. 1570 */ 1571 if (parent && parent != dndb) 1572 dbuf_rele(parent, db); 1573 } 1574 1575 static int 1576 dbuf_findbp(dnode_t *dn, int level, uint64_t blkid, int fail_sparse, 1577 dmu_buf_impl_t **parentp, blkptr_t **bpp) 1578 { 1579 int nlevels, epbs; 1580 1581 *parentp = NULL; 1582 *bpp = NULL; 1583 1584 ASSERT(blkid != DMU_BONUS_BLKID); 1585 1586 if (blkid == DMU_SPILL_BLKID) { 1587 mutex_enter(&dn->dn_mtx); 1588 if (dn->dn_have_spill && 1589 (dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR)) 1590 *bpp = &dn->dn_phys->dn_spill; 1591 else 1592 *bpp = NULL; 1593 dbuf_add_ref(dn->dn_dbuf, NULL); 1594 *parentp = dn->dn_dbuf; 1595 mutex_exit(&dn->dn_mtx); 1596 return (0); 1597 } 1598 1599 if (dn->dn_phys->dn_nlevels == 0) 1600 nlevels = 1; 1601 else 1602 nlevels = dn->dn_phys->dn_nlevels; 1603 1604 epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT; 1605 1606 ASSERT3U(level * epbs, <, 64); 1607 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 1608 if (level >= nlevels || 1609 (blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))) { 1610 /* the buffer has no parent yet */ 1611 return (SET_ERROR(ENOENT)); 1612 } else if (level < nlevels-1) { 1613 /* this block is referenced from an indirect block */ 1614 int err = dbuf_hold_impl(dn, level+1, 1615 blkid >> epbs, fail_sparse, NULL, parentp); 1616 if (err) 1617 return (err); 1618 err = dbuf_read(*parentp, NULL, 1619 (DB_RF_HAVESTRUCT | DB_RF_NOPREFETCH | DB_RF_CANFAIL)); 1620 if (err) { 1621 dbuf_rele(*parentp, NULL); 1622 *parentp = NULL; 1623 return (err); 1624 } 1625 *bpp = ((blkptr_t *)(*parentp)->db.db_data) + 1626 (blkid & ((1ULL << epbs) - 1)); 1627 return (0); 1628 } else { 1629 /* the block is referenced from the dnode */ 1630 ASSERT3U(level, ==, nlevels-1); 1631 ASSERT(dn->dn_phys->dn_nblkptr == 0 || 1632 blkid < dn->dn_phys->dn_nblkptr); 1633 if (dn->dn_dbuf) { 1634 dbuf_add_ref(dn->dn_dbuf, NULL); 1635 *parentp = dn->dn_dbuf; 1636 } 1637 *bpp = &dn->dn_phys->dn_blkptr[blkid]; 1638 return (0); 1639 } 1640 } 1641 1642 static dmu_buf_impl_t * 1643 dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid, 1644 dmu_buf_impl_t *parent, blkptr_t *blkptr) 1645 { 1646 objset_t *os = dn->dn_objset; 1647 dmu_buf_impl_t *db, *odb; 1648 1649 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 1650 ASSERT(dn->dn_type != DMU_OT_NONE); 1651 1652 db = kmem_cache_alloc(dbuf_cache, KM_SLEEP); 1653 1654 db->db_objset = os; 1655 db->db.db_object = dn->dn_object; 1656 db->db_level = level; 1657 db->db_blkid = blkid; 1658 db->db_last_dirty = NULL; 1659 db->db_dirtycnt = 0; 1660 db->db_dnode_handle = dn->dn_handle; 1661 db->db_parent = parent; 1662 db->db_blkptr = blkptr; 1663 1664 db->db_user_ptr = NULL; 1665 db->db_user_data_ptr_ptr = NULL; 1666 db->db_evict_func = NULL; 1667 db->db_immediate_evict = 0; 1668 db->db_freed_in_flight = 0; 1669 1670 if (blkid == DMU_BONUS_BLKID) { 1671 ASSERT3P(parent, ==, dn->dn_dbuf); 1672 db->db.db_size = DN_MAX_BONUSLEN - 1673 (dn->dn_nblkptr-1) * sizeof (blkptr_t); 1674 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen); 1675 db->db.db_offset = DMU_BONUS_BLKID; 1676 db->db_state = DB_UNCACHED; 1677 /* the bonus dbuf is not placed in the hash table */ 1678 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER); 1679 return (db); 1680 } else if (blkid == DMU_SPILL_BLKID) { 1681 db->db.db_size = (blkptr != NULL) ? 1682 BP_GET_LSIZE(blkptr) : SPA_MINBLOCKSIZE; 1683 db->db.db_offset = 0; 1684 } else { 1685 int blocksize = 1686 db->db_level ? 1 << dn->dn_indblkshift : dn->dn_datablksz; 1687 db->db.db_size = blocksize; 1688 db->db.db_offset = db->db_blkid * blocksize; 1689 } 1690 1691 /* 1692 * Hold the dn_dbufs_mtx while we get the new dbuf 1693 * in the hash table *and* added to the dbufs list. 1694 * This prevents a possible deadlock with someone 1695 * trying to look up this dbuf before its added to the 1696 * dn_dbufs list. 1697 */ 1698 mutex_enter(&dn->dn_dbufs_mtx); 1699 db->db_state = DB_EVICTING; 1700 if ((odb = dbuf_hash_insert(db)) != NULL) { 1701 /* someone else inserted it first */ 1702 kmem_cache_free(dbuf_cache, db); 1703 mutex_exit(&dn->dn_dbufs_mtx); 1704 return (odb); 1705 } 1706 list_insert_head(&dn->dn_dbufs, db); 1707 if (db->db_level == 0 && db->db_blkid >= 1708 dn->dn_unlisted_l0_blkid) 1709 dn->dn_unlisted_l0_blkid = db->db_blkid + 1; 1710 db->db_state = DB_UNCACHED; 1711 mutex_exit(&dn->dn_dbufs_mtx); 1712 arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER); 1713 1714 if (parent && parent != dn->dn_dbuf) 1715 dbuf_add_ref(parent, db); 1716 1717 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT || 1718 refcount_count(&dn->dn_holds) > 0); 1719 (void) refcount_add(&dn->dn_holds, db); 1720 (void) atomic_inc_32_nv(&dn->dn_dbufs_count); 1721 1722 dprintf_dbuf(db, "db=%p\n", db); 1723 1724 return (db); 1725 } 1726 1727 static int 1728 dbuf_do_evict(void *private) 1729 { 1730 arc_buf_t *buf = private; 1731 dmu_buf_impl_t *db = buf->b_private; 1732 1733 if (!MUTEX_HELD(&db->db_mtx)) 1734 mutex_enter(&db->db_mtx); 1735 1736 ASSERT(refcount_is_zero(&db->db_holds)); 1737 1738 if (db->db_state != DB_EVICTING) { 1739 ASSERT(db->db_state == DB_CACHED); 1740 DBUF_VERIFY(db); 1741 db->db_buf = NULL; 1742 dbuf_evict(db); 1743 } else { 1744 mutex_exit(&db->db_mtx); 1745 dbuf_destroy(db); 1746 } 1747 return (0); 1748 } 1749 1750 static void 1751 dbuf_destroy(dmu_buf_impl_t *db) 1752 { 1753 ASSERT(refcount_is_zero(&db->db_holds)); 1754 1755 if (db->db_blkid != DMU_BONUS_BLKID) { 1756 /* 1757 * If this dbuf is still on the dn_dbufs list, 1758 * remove it from that list. 1759 */ 1760 if (db->db_dnode_handle != NULL) { 1761 dnode_t *dn; 1762 1763 DB_DNODE_ENTER(db); 1764 dn = DB_DNODE(db); 1765 mutex_enter(&dn->dn_dbufs_mtx); 1766 list_remove(&dn->dn_dbufs, db); 1767 (void) atomic_dec_32_nv(&dn->dn_dbufs_count); 1768 mutex_exit(&dn->dn_dbufs_mtx); 1769 DB_DNODE_EXIT(db); 1770 /* 1771 * Decrementing the dbuf count means that the hold 1772 * corresponding to the removed dbuf is no longer 1773 * discounted in dnode_move(), so the dnode cannot be 1774 * moved until after we release the hold. 1775 */ 1776 dnode_rele(dn, db); 1777 db->db_dnode_handle = NULL; 1778 } 1779 dbuf_hash_remove(db); 1780 } 1781 db->db_parent = NULL; 1782 db->db_buf = NULL; 1783 1784 ASSERT(!list_link_active(&db->db_link)); 1785 ASSERT(db->db.db_data == NULL); 1786 ASSERT(db->db_hash_next == NULL); 1787 ASSERT(db->db_blkptr == NULL); 1788 ASSERT(db->db_data_pending == NULL); 1789 1790 kmem_cache_free(dbuf_cache, db); 1791 arc_space_return(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER); 1792 } 1793 1794 void 1795 dbuf_prefetch(dnode_t *dn, uint64_t blkid, zio_priority_t prio) 1796 { 1797 dmu_buf_impl_t *db = NULL; 1798 blkptr_t *bp = NULL; 1799 1800 ASSERT(blkid != DMU_BONUS_BLKID); 1801 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 1802 1803 if (dnode_block_freed(dn, blkid)) 1804 return; 1805 1806 /* dbuf_find() returns with db_mtx held */ 1807 if (db = dbuf_find(dn, 0, blkid)) { 1808 /* 1809 * This dbuf is already in the cache. We assume that 1810 * it is already CACHED, or else about to be either 1811 * read or filled. 1812 */ 1813 mutex_exit(&db->db_mtx); 1814 return; 1815 } 1816 1817 if (dbuf_findbp(dn, 0, blkid, TRUE, &db, &bp) == 0) { 1818 if (bp && !BP_IS_HOLE(bp)) { 1819 dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset; 1820 uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH; 1821 zbookmark_t zb; 1822 1823 SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET, 1824 dn->dn_object, 0, blkid); 1825 1826 (void) arc_read(NULL, dn->dn_objset->os_spa, 1827 bp, NULL, NULL, prio, 1828 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE, 1829 &aflags, &zb); 1830 } 1831 if (db) 1832 dbuf_rele(db, NULL); 1833 } 1834 } 1835 1836 /* 1837 * Returns with db_holds incremented, and db_mtx not held. 1838 * Note: dn_struct_rwlock must be held. 1839 */ 1840 int 1841 dbuf_hold_impl(dnode_t *dn, uint8_t level, uint64_t blkid, int fail_sparse, 1842 void *tag, dmu_buf_impl_t **dbp) 1843 { 1844 dmu_buf_impl_t *db, *parent = NULL; 1845 1846 ASSERT(blkid != DMU_BONUS_BLKID); 1847 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); 1848 ASSERT3U(dn->dn_nlevels, >, level); 1849 1850 *dbp = NULL; 1851 top: 1852 /* dbuf_find() returns with db_mtx held */ 1853 db = dbuf_find(dn, level, blkid); 1854 1855 if (db == NULL) { 1856 blkptr_t *bp = NULL; 1857 int err; 1858 1859 ASSERT3P(parent, ==, NULL); 1860 err = dbuf_findbp(dn, level, blkid, fail_sparse, &parent, &bp); 1861 if (fail_sparse) { 1862 if (err == 0 && bp && BP_IS_HOLE(bp)) 1863 err = SET_ERROR(ENOENT); 1864 if (err) { 1865 if (parent) 1866 dbuf_rele(parent, NULL); 1867 return (err); 1868 } 1869 } 1870 if (err && err != ENOENT) 1871 return (err); 1872 db = dbuf_create(dn, level, blkid, parent, bp); 1873 } 1874 1875 if (db->db_buf && refcount_is_zero(&db->db_holds)) { 1876 arc_buf_add_ref(db->db_buf, db); 1877 if (db->db_buf->b_data == NULL) { 1878 dbuf_clear(db); 1879 if (parent) { 1880 dbuf_rele(parent, NULL); 1881 parent = NULL; 1882 } 1883 goto top; 1884 } 1885 ASSERT3P(db->db.db_data, ==, db->db_buf->b_data); 1886 } 1887 1888 ASSERT(db->db_buf == NULL || arc_referenced(db->db_buf)); 1889 1890 /* 1891 * If this buffer is currently syncing out, and we are are 1892 * still referencing it from db_data, we need to make a copy 1893 * of it in case we decide we want to dirty it again in this txg. 1894 */ 1895 if (db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID && 1896 dn->dn_object != DMU_META_DNODE_OBJECT && 1897 db->db_state == DB_CACHED && db->db_data_pending) { 1898 dbuf_dirty_record_t *dr = db->db_data_pending; 1899 1900 if (dr->dt.dl.dr_data == db->db_buf) { 1901 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 1902 1903 dbuf_set_data(db, 1904 arc_buf_alloc(dn->dn_objset->os_spa, 1905 db->db.db_size, db, type)); 1906 bcopy(dr->dt.dl.dr_data->b_data, db->db.db_data, 1907 db->db.db_size); 1908 } 1909 } 1910 1911 (void) refcount_add(&db->db_holds, tag); 1912 dbuf_update_data(db); 1913 DBUF_VERIFY(db); 1914 mutex_exit(&db->db_mtx); 1915 1916 /* NOTE: we can't rele the parent until after we drop the db_mtx */ 1917 if (parent) 1918 dbuf_rele(parent, NULL); 1919 1920 ASSERT3P(DB_DNODE(db), ==, dn); 1921 ASSERT3U(db->db_blkid, ==, blkid); 1922 ASSERT3U(db->db_level, ==, level); 1923 *dbp = db; 1924 1925 return (0); 1926 } 1927 1928 dmu_buf_impl_t * 1929 dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag) 1930 { 1931 dmu_buf_impl_t *db; 1932 int err = dbuf_hold_impl(dn, 0, blkid, FALSE, tag, &db); 1933 return (err ? NULL : db); 1934 } 1935 1936 dmu_buf_impl_t * 1937 dbuf_hold_level(dnode_t *dn, int level, uint64_t blkid, void *tag) 1938 { 1939 dmu_buf_impl_t *db; 1940 int err = dbuf_hold_impl(dn, level, blkid, FALSE, tag, &db); 1941 return (err ? NULL : db); 1942 } 1943 1944 void 1945 dbuf_create_bonus(dnode_t *dn) 1946 { 1947 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock)); 1948 1949 ASSERT(dn->dn_bonus == NULL); 1950 dn->dn_bonus = dbuf_create(dn, 0, DMU_BONUS_BLKID, dn->dn_dbuf, NULL); 1951 } 1952 1953 int 1954 dbuf_spill_set_blksz(dmu_buf_t *db_fake, uint64_t blksz, dmu_tx_t *tx) 1955 { 1956 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 1957 dnode_t *dn; 1958 1959 if (db->db_blkid != DMU_SPILL_BLKID) 1960 return (SET_ERROR(ENOTSUP)); 1961 if (blksz == 0) 1962 blksz = SPA_MINBLOCKSIZE; 1963 if (blksz > SPA_MAXBLOCKSIZE) 1964 blksz = SPA_MAXBLOCKSIZE; 1965 else 1966 blksz = P2ROUNDUP(blksz, SPA_MINBLOCKSIZE); 1967 1968 DB_DNODE_ENTER(db); 1969 dn = DB_DNODE(db); 1970 rw_enter(&dn->dn_struct_rwlock, RW_WRITER); 1971 dbuf_new_size(db, blksz, tx); 1972 rw_exit(&dn->dn_struct_rwlock); 1973 DB_DNODE_EXIT(db); 1974 1975 return (0); 1976 } 1977 1978 void 1979 dbuf_rm_spill(dnode_t *dn, dmu_tx_t *tx) 1980 { 1981 dbuf_free_range(dn, DMU_SPILL_BLKID, DMU_SPILL_BLKID, tx); 1982 } 1983 1984 #pragma weak dmu_buf_add_ref = dbuf_add_ref 1985 void 1986 dbuf_add_ref(dmu_buf_impl_t *db, void *tag) 1987 { 1988 int64_t holds = refcount_add(&db->db_holds, tag); 1989 ASSERT(holds > 1); 1990 } 1991 1992 /* 1993 * If you call dbuf_rele() you had better not be referencing the dnode handle 1994 * unless you have some other direct or indirect hold on the dnode. (An indirect 1995 * hold is a hold on one of the dnode's dbufs, including the bonus buffer.) 1996 * Without that, the dbuf_rele() could lead to a dnode_rele() followed by the 1997 * dnode's parent dbuf evicting its dnode handles. 1998 */ 1999 void 2000 dbuf_rele(dmu_buf_impl_t *db, void *tag) 2001 { 2002 mutex_enter(&db->db_mtx); 2003 dbuf_rele_and_unlock(db, tag); 2004 } 2005 2006 void 2007 dmu_buf_rele(dmu_buf_t *db, void *tag) 2008 { 2009 dbuf_rele((dmu_buf_impl_t *)db, tag); 2010 } 2011 2012 /* 2013 * dbuf_rele() for an already-locked dbuf. This is necessary to allow 2014 * db_dirtycnt and db_holds to be updated atomically. 2015 */ 2016 void 2017 dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag) 2018 { 2019 int64_t holds; 2020 2021 ASSERT(MUTEX_HELD(&db->db_mtx)); 2022 DBUF_VERIFY(db); 2023 2024 /* 2025 * Remove the reference to the dbuf before removing its hold on the 2026 * dnode so we can guarantee in dnode_move() that a referenced bonus 2027 * buffer has a corresponding dnode hold. 2028 */ 2029 holds = refcount_remove(&db->db_holds, tag); 2030 ASSERT(holds >= 0); 2031 2032 /* 2033 * We can't freeze indirects if there is a possibility that they 2034 * may be modified in the current syncing context. 2035 */ 2036 if (db->db_buf && holds == (db->db_level == 0 ? db->db_dirtycnt : 0)) 2037 arc_buf_freeze(db->db_buf); 2038 2039 if (holds == db->db_dirtycnt && 2040 db->db_level == 0 && db->db_immediate_evict) 2041 dbuf_evict_user(db); 2042 2043 if (holds == 0) { 2044 if (db->db_blkid == DMU_BONUS_BLKID) { 2045 mutex_exit(&db->db_mtx); 2046 2047 /* 2048 * If the dnode moves here, we cannot cross this barrier 2049 * until the move completes. 2050 */ 2051 DB_DNODE_ENTER(db); 2052 (void) atomic_dec_32_nv(&DB_DNODE(db)->dn_dbufs_count); 2053 DB_DNODE_EXIT(db); 2054 /* 2055 * The bonus buffer's dnode hold is no longer discounted 2056 * in dnode_move(). The dnode cannot move until after 2057 * the dnode_rele(). 2058 */ 2059 dnode_rele(DB_DNODE(db), db); 2060 } else if (db->db_buf == NULL) { 2061 /* 2062 * This is a special case: we never associated this 2063 * dbuf with any data allocated from the ARC. 2064 */ 2065 ASSERT(db->db_state == DB_UNCACHED || 2066 db->db_state == DB_NOFILL); 2067 dbuf_evict(db); 2068 } else if (arc_released(db->db_buf)) { 2069 arc_buf_t *buf = db->db_buf; 2070 /* 2071 * This dbuf has anonymous data associated with it. 2072 */ 2073 dbuf_set_data(db, NULL); 2074 VERIFY(arc_buf_remove_ref(buf, db)); 2075 dbuf_evict(db); 2076 } else { 2077 VERIFY(!arc_buf_remove_ref(db->db_buf, db)); 2078 2079 /* 2080 * A dbuf will be eligible for eviction if either the 2081 * 'primarycache' property is set or a duplicate 2082 * copy of this buffer is already cached in the arc. 2083 * 2084 * In the case of the 'primarycache' a buffer 2085 * is considered for eviction if it matches the 2086 * criteria set in the property. 2087 * 2088 * To decide if our buffer is considered a 2089 * duplicate, we must call into the arc to determine 2090 * if multiple buffers are referencing the same 2091 * block on-disk. If so, then we simply evict 2092 * ourselves. 2093 */ 2094 if (!DBUF_IS_CACHEABLE(db) || 2095 arc_buf_eviction_needed(db->db_buf)) 2096 dbuf_clear(db); 2097 else 2098 mutex_exit(&db->db_mtx); 2099 } 2100 } else { 2101 mutex_exit(&db->db_mtx); 2102 } 2103 } 2104 2105 #pragma weak dmu_buf_refcount = dbuf_refcount 2106 uint64_t 2107 dbuf_refcount(dmu_buf_impl_t *db) 2108 { 2109 return (refcount_count(&db->db_holds)); 2110 } 2111 2112 void * 2113 dmu_buf_set_user(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr, 2114 dmu_buf_evict_func_t *evict_func) 2115 { 2116 return (dmu_buf_update_user(db_fake, NULL, user_ptr, 2117 user_data_ptr_ptr, evict_func)); 2118 } 2119 2120 void * 2121 dmu_buf_set_user_ie(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr, 2122 dmu_buf_evict_func_t *evict_func) 2123 { 2124 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 2125 2126 db->db_immediate_evict = TRUE; 2127 return (dmu_buf_update_user(db_fake, NULL, user_ptr, 2128 user_data_ptr_ptr, evict_func)); 2129 } 2130 2131 void * 2132 dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr, void *user_ptr, 2133 void *user_data_ptr_ptr, dmu_buf_evict_func_t *evict_func) 2134 { 2135 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 2136 ASSERT(db->db_level == 0); 2137 2138 ASSERT((user_ptr == NULL) == (evict_func == NULL)); 2139 2140 mutex_enter(&db->db_mtx); 2141 2142 if (db->db_user_ptr == old_user_ptr) { 2143 db->db_user_ptr = user_ptr; 2144 db->db_user_data_ptr_ptr = user_data_ptr_ptr; 2145 db->db_evict_func = evict_func; 2146 2147 dbuf_update_data(db); 2148 } else { 2149 old_user_ptr = db->db_user_ptr; 2150 } 2151 2152 mutex_exit(&db->db_mtx); 2153 return (old_user_ptr); 2154 } 2155 2156 void * 2157 dmu_buf_get_user(dmu_buf_t *db_fake) 2158 { 2159 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; 2160 ASSERT(!refcount_is_zero(&db->db_holds)); 2161 2162 return (db->db_user_ptr); 2163 } 2164 2165 boolean_t 2166 dmu_buf_freeable(dmu_buf_t *dbuf) 2167 { 2168 boolean_t res = B_FALSE; 2169 dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf; 2170 2171 if (db->db_blkptr) 2172 res = dsl_dataset_block_freeable(db->db_objset->os_dsl_dataset, 2173 db->db_blkptr, db->db_blkptr->blk_birth); 2174 2175 return (res); 2176 } 2177 2178 blkptr_t * 2179 dmu_buf_get_blkptr(dmu_buf_t *db) 2180 { 2181 dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db; 2182 return (dbi->db_blkptr); 2183 } 2184 2185 static void 2186 dbuf_check_blkptr(dnode_t *dn, dmu_buf_impl_t *db) 2187 { 2188 /* ASSERT(dmu_tx_is_syncing(tx) */ 2189 ASSERT(MUTEX_HELD(&db->db_mtx)); 2190 2191 if (db->db_blkptr != NULL) 2192 return; 2193 2194 if (db->db_blkid == DMU_SPILL_BLKID) { 2195 db->db_blkptr = &dn->dn_phys->dn_spill; 2196 BP_ZERO(db->db_blkptr); 2197 return; 2198 } 2199 if (db->db_level == dn->dn_phys->dn_nlevels-1) { 2200 /* 2201 * This buffer was allocated at a time when there was 2202 * no available blkptrs from the dnode, or it was 2203 * inappropriate to hook it in (i.e., nlevels mis-match). 2204 */ 2205 ASSERT(db->db_blkid < dn->dn_phys->dn_nblkptr); 2206 ASSERT(db->db_parent == NULL); 2207 db->db_parent = dn->dn_dbuf; 2208 db->db_blkptr = &dn->dn_phys->dn_blkptr[db->db_blkid]; 2209 DBUF_VERIFY(db); 2210 } else { 2211 dmu_buf_impl_t *parent = db->db_parent; 2212 int epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT; 2213 2214 ASSERT(dn->dn_phys->dn_nlevels > 1); 2215 if (parent == NULL) { 2216 mutex_exit(&db->db_mtx); 2217 rw_enter(&dn->dn_struct_rwlock, RW_READER); 2218 (void) dbuf_hold_impl(dn, db->db_level+1, 2219 db->db_blkid >> epbs, FALSE, db, &parent); 2220 rw_exit(&dn->dn_struct_rwlock); 2221 mutex_enter(&db->db_mtx); 2222 db->db_parent = parent; 2223 } 2224 db->db_blkptr = (blkptr_t *)parent->db.db_data + 2225 (db->db_blkid & ((1ULL << epbs) - 1)); 2226 DBUF_VERIFY(db); 2227 } 2228 } 2229 2230 static void 2231 dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx) 2232 { 2233 dmu_buf_impl_t *db = dr->dr_dbuf; 2234 dnode_t *dn; 2235 zio_t *zio; 2236 2237 ASSERT(dmu_tx_is_syncing(tx)); 2238 2239 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr); 2240 2241 mutex_enter(&db->db_mtx); 2242 2243 ASSERT(db->db_level > 0); 2244 DBUF_VERIFY(db); 2245 2246 /* Read the block if it hasn't been read yet. */ 2247 if (db->db_buf == NULL) { 2248 mutex_exit(&db->db_mtx); 2249 (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED); 2250 mutex_enter(&db->db_mtx); 2251 } 2252 ASSERT3U(db->db_state, ==, DB_CACHED); 2253 ASSERT(db->db_buf != NULL); 2254 2255 DB_DNODE_ENTER(db); 2256 dn = DB_DNODE(db); 2257 /* Indirect block size must match what the dnode thinks it is. */ 2258 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift); 2259 dbuf_check_blkptr(dn, db); 2260 DB_DNODE_EXIT(db); 2261 2262 /* Provide the pending dirty record to child dbufs */ 2263 db->db_data_pending = dr; 2264 2265 mutex_exit(&db->db_mtx); 2266 dbuf_write(dr, db->db_buf, tx); 2267 2268 zio = dr->dr_zio; 2269 mutex_enter(&dr->dt.di.dr_mtx); 2270 dbuf_sync_list(&dr->dt.di.dr_children, tx); 2271 ASSERT(list_head(&dr->dt.di.dr_children) == NULL); 2272 mutex_exit(&dr->dt.di.dr_mtx); 2273 zio_nowait(zio); 2274 } 2275 2276 static void 2277 dbuf_sync_leaf(dbuf_dirty_record_t *dr, dmu_tx_t *tx) 2278 { 2279 arc_buf_t **datap = &dr->dt.dl.dr_data; 2280 dmu_buf_impl_t *db = dr->dr_dbuf; 2281 dnode_t *dn; 2282 objset_t *os; 2283 uint64_t txg = tx->tx_txg; 2284 2285 ASSERT(dmu_tx_is_syncing(tx)); 2286 2287 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr); 2288 2289 mutex_enter(&db->db_mtx); 2290 /* 2291 * To be synced, we must be dirtied. But we 2292 * might have been freed after the dirty. 2293 */ 2294 if (db->db_state == DB_UNCACHED) { 2295 /* This buffer has been freed since it was dirtied */ 2296 ASSERT(db->db.db_data == NULL); 2297 } else if (db->db_state == DB_FILL) { 2298 /* This buffer was freed and is now being re-filled */ 2299 ASSERT(db->db.db_data != dr->dt.dl.dr_data); 2300 } else { 2301 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_NOFILL); 2302 } 2303 DBUF_VERIFY(db); 2304 2305 DB_DNODE_ENTER(db); 2306 dn = DB_DNODE(db); 2307 2308 if (db->db_blkid == DMU_SPILL_BLKID) { 2309 mutex_enter(&dn->dn_mtx); 2310 dn->dn_phys->dn_flags |= DNODE_FLAG_SPILL_BLKPTR; 2311 mutex_exit(&dn->dn_mtx); 2312 } 2313 2314 /* 2315 * If this is a bonus buffer, simply copy the bonus data into the 2316 * dnode. It will be written out when the dnode is synced (and it 2317 * will be synced, since it must have been dirty for dbuf_sync to 2318 * be called). 2319 */ 2320 if (db->db_blkid == DMU_BONUS_BLKID) { 2321 dbuf_dirty_record_t **drp; 2322 2323 ASSERT(*datap != NULL); 2324 ASSERT0(db->db_level); 2325 ASSERT3U(dn->dn_phys->dn_bonuslen, <=, DN_MAX_BONUSLEN); 2326 bcopy(*datap, DN_BONUS(dn->dn_phys), dn->dn_phys->dn_bonuslen); 2327 DB_DNODE_EXIT(db); 2328 2329 if (*datap != db->db.db_data) { 2330 zio_buf_free(*datap, DN_MAX_BONUSLEN); 2331 arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER); 2332 } 2333 db->db_data_pending = NULL; 2334 drp = &db->db_last_dirty; 2335 while (*drp != dr) 2336 drp = &(*drp)->dr_next; 2337 ASSERT(dr->dr_next == NULL); 2338 ASSERT(dr->dr_dbuf == db); 2339 *drp = dr->dr_next; 2340 kmem_free(dr, sizeof (dbuf_dirty_record_t)); 2341 ASSERT(db->db_dirtycnt > 0); 2342 db->db_dirtycnt -= 1; 2343 dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg); 2344 return; 2345 } 2346 2347 os = dn->dn_objset; 2348 2349 /* 2350 * This function may have dropped the db_mtx lock allowing a dmu_sync 2351 * operation to sneak in. As a result, we need to ensure that we 2352 * don't check the dr_override_state until we have returned from 2353 * dbuf_check_blkptr. 2354 */ 2355 dbuf_check_blkptr(dn, db); 2356 2357 /* 2358 * If this buffer is in the middle of an immediate write, 2359 * wait for the synchronous IO to complete. 2360 */ 2361 while (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC) { 2362 ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT); 2363 cv_wait(&db->db_changed, &db->db_mtx); 2364 ASSERT(dr->dt.dl.dr_override_state != DR_NOT_OVERRIDDEN); 2365 } 2366 2367 if (db->db_state != DB_NOFILL && 2368 dn->dn_object != DMU_META_DNODE_OBJECT && 2369 refcount_count(&db->db_holds) > 1 && 2370 dr->dt.dl.dr_override_state != DR_OVERRIDDEN && 2371 *datap == db->db_buf) { 2372 /* 2373 * If this buffer is currently "in use" (i.e., there 2374 * are active holds and db_data still references it), 2375 * then make a copy before we start the write so that 2376 * any modifications from the open txg will not leak 2377 * into this write. 2378 * 2379 * NOTE: this copy does not need to be made for 2380 * objects only modified in the syncing context (e.g. 2381 * DNONE_DNODE blocks). 2382 */ 2383 int blksz = arc_buf_size(*datap); 2384 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); 2385 *datap = arc_buf_alloc(os->os_spa, blksz, db, type); 2386 bcopy(db->db.db_data, (*datap)->b_data, blksz); 2387 } 2388 db->db_data_pending = dr; 2389 2390 mutex_exit(&db->db_mtx); 2391 2392 dbuf_write(dr, *datap, tx); 2393 2394 ASSERT(!list_link_active(&dr->dr_dirty_node)); 2395 if (dn->dn_object == DMU_META_DNODE_OBJECT) { 2396 list_insert_tail(&dn->dn_dirty_records[txg&TXG_MASK], dr); 2397 DB_DNODE_EXIT(db); 2398 } else { 2399 /* 2400 * Although zio_nowait() does not "wait for an IO", it does 2401 * initiate the IO. If this is an empty write it seems plausible 2402 * that the IO could actually be completed before the nowait 2403 * returns. We need to DB_DNODE_EXIT() first in case 2404 * zio_nowait() invalidates the dbuf. 2405 */ 2406 DB_DNODE_EXIT(db); 2407 zio_nowait(dr->dr_zio); 2408 } 2409 } 2410 2411 void 2412 dbuf_sync_list(list_t *list, dmu_tx_t *tx) 2413 { 2414 dbuf_dirty_record_t *dr; 2415 2416 while (dr = list_head(list)) { 2417 if (dr->dr_zio != NULL) { 2418 /* 2419 * If we find an already initialized zio then we 2420 * are processing the meta-dnode, and we have finished. 2421 * The dbufs for all dnodes are put back on the list 2422 * during processing, so that we can zio_wait() 2423 * these IOs after initiating all child IOs. 2424 */ 2425 ASSERT3U(dr->dr_dbuf->db.db_object, ==, 2426 DMU_META_DNODE_OBJECT); 2427 break; 2428 } 2429 list_remove(list, dr); 2430 if (dr->dr_dbuf->db_level > 0) 2431 dbuf_sync_indirect(dr, tx); 2432 else 2433 dbuf_sync_leaf(dr, tx); 2434 } 2435 } 2436 2437 /* ARGSUSED */ 2438 static void 2439 dbuf_write_ready(zio_t *zio, arc_buf_t *buf, void *vdb) 2440 { 2441 dmu_buf_impl_t *db = vdb; 2442 dnode_t *dn; 2443 blkptr_t *bp = zio->io_bp; 2444 blkptr_t *bp_orig = &zio->io_bp_orig; 2445 spa_t *spa = zio->io_spa; 2446 int64_t delta; 2447 uint64_t fill = 0; 2448 int i; 2449 2450 ASSERT(db->db_blkptr == bp); 2451 2452 DB_DNODE_ENTER(db); 2453 dn = DB_DNODE(db); 2454 delta = bp_get_dsize_sync(spa, bp) - bp_get_dsize_sync(spa, bp_orig); 2455 dnode_diduse_space(dn, delta - zio->io_prev_space_delta); 2456 zio->io_prev_space_delta = delta; 2457 2458 if (bp->blk_birth != 0) { 2459 ASSERT((db->db_blkid != DMU_SPILL_BLKID && 2460 BP_GET_TYPE(bp) == dn->dn_type) || 2461 (db->db_blkid == DMU_SPILL_BLKID && 2462 BP_GET_TYPE(bp) == dn->dn_bonustype)); 2463 ASSERT(BP_GET_LEVEL(bp) == db->db_level); 2464 } 2465 2466 mutex_enter(&db->db_mtx); 2467 2468 #ifdef ZFS_DEBUG 2469 if (db->db_blkid == DMU_SPILL_BLKID) { 2470 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR); 2471 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) && 2472 db->db_blkptr == &dn->dn_phys->dn_spill); 2473 } 2474 #endif 2475 2476 if (db->db_level == 0) { 2477 mutex_enter(&dn->dn_mtx); 2478 if (db->db_blkid > dn->dn_phys->dn_maxblkid && 2479 db->db_blkid != DMU_SPILL_BLKID) 2480 dn->dn_phys->dn_maxblkid = db->db_blkid; 2481 mutex_exit(&dn->dn_mtx); 2482 2483 if (dn->dn_type == DMU_OT_DNODE) { 2484 dnode_phys_t *dnp = db->db.db_data; 2485 for (i = db->db.db_size >> DNODE_SHIFT; i > 0; 2486 i--, dnp++) { 2487 if (dnp->dn_type != DMU_OT_NONE) 2488 fill++; 2489 } 2490 } else { 2491 if (BP_IS_HOLE(bp)) { 2492 fill = 0; 2493 } else { 2494 fill = 1; 2495 } 2496 } 2497 } else { 2498 blkptr_t *ibp = db->db.db_data; 2499 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift); 2500 for (i = db->db.db_size >> SPA_BLKPTRSHIFT; i > 0; i--, ibp++) { 2501 if (BP_IS_HOLE(ibp)) 2502 continue; 2503 fill += ibp->blk_fill; 2504 } 2505 } 2506 DB_DNODE_EXIT(db); 2507 2508 bp->blk_fill = fill; 2509 2510 mutex_exit(&db->db_mtx); 2511 } 2512 2513 /* 2514 * The SPA will call this callback several times for each zio - once 2515 * for every physical child i/o (zio->io_phys_children times). This 2516 * allows the DMU to monitor the progress of each logical i/o. For example, 2517 * there may be 2 copies of an indirect block, or many fragments of a RAID-Z 2518 * block. There may be a long delay before all copies/fragments are completed, 2519 * so this callback allows us to retire dirty space gradually, as the physical 2520 * i/os complete. 2521 */ 2522 /* ARGSUSED */ 2523 static void 2524 dbuf_write_physdone(zio_t *zio, arc_buf_t *buf, void *arg) 2525 { 2526 dmu_buf_impl_t *db = arg; 2527 objset_t *os = db->db_objset; 2528 dsl_pool_t *dp = dmu_objset_pool(os); 2529 dbuf_dirty_record_t *dr; 2530 int delta = 0; 2531 2532 dr = db->db_data_pending; 2533 ASSERT3U(dr->dr_txg, ==, zio->io_txg); 2534 2535 /* 2536 * The callback will be called io_phys_children times. Retire one 2537 * portion of our dirty space each time we are called. Any rounding 2538 * error will be cleaned up by dsl_pool_sync()'s call to 2539 * dsl_pool_undirty_space(). 2540 */ 2541 delta = dr->dr_accounted / zio->io_phys_children; 2542 dsl_pool_undirty_space(dp, delta, zio->io_txg); 2543 } 2544 2545 /* ARGSUSED */ 2546 static void 2547 dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb) 2548 { 2549 dmu_buf_impl_t *db = vdb; 2550 blkptr_t *bp_orig = &zio->io_bp_orig; 2551 blkptr_t *bp = db->db_blkptr; 2552 objset_t *os = db->db_objset; 2553 dmu_tx_t *tx = os->os_synctx; 2554 dbuf_dirty_record_t **drp, *dr; 2555 2556 ASSERT0(zio->io_error); 2557 ASSERT(db->db_blkptr == bp); 2558 2559 /* 2560 * For nopwrites and rewrites we ensure that the bp matches our 2561 * original and bypass all the accounting. 2562 */ 2563 if (zio->io_flags & (ZIO_FLAG_IO_REWRITE | ZIO_FLAG_NOPWRITE)) { 2564 ASSERT(BP_EQUAL(bp, bp_orig)); 2565 } else { 2566 dsl_dataset_t *ds = os->os_dsl_dataset; 2567 (void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE); 2568 dsl_dataset_block_born(ds, bp, tx); 2569 } 2570 2571 mutex_enter(&db->db_mtx); 2572 2573 DBUF_VERIFY(db); 2574 2575 drp = &db->db_last_dirty; 2576 while ((dr = *drp) != db->db_data_pending) 2577 drp = &dr->dr_next; 2578 ASSERT(!list_link_active(&dr->dr_dirty_node)); 2579 ASSERT(dr->dr_dbuf == db); 2580 ASSERT(dr->dr_next == NULL); 2581 *drp = dr->dr_next; 2582 2583 #ifdef ZFS_DEBUG 2584 if (db->db_blkid == DMU_SPILL_BLKID) { 2585 dnode_t *dn; 2586 2587 DB_DNODE_ENTER(db); 2588 dn = DB_DNODE(db); 2589 ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR); 2590 ASSERT(!(BP_IS_HOLE(db->db_blkptr)) && 2591 db->db_blkptr == &dn->dn_phys->dn_spill); 2592 DB_DNODE_EXIT(db); 2593 } 2594 #endif 2595 2596 if (db->db_level == 0) { 2597 ASSERT(db->db_blkid != DMU_BONUS_BLKID); 2598 ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN); 2599 if (db->db_state != DB_NOFILL) { 2600 if (dr->dt.dl.dr_data != db->db_buf) 2601 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data, 2602 db)); 2603 else if (!arc_released(db->db_buf)) 2604 arc_set_callback(db->db_buf, dbuf_do_evict, db); 2605 } 2606 } else { 2607 dnode_t *dn; 2608 2609 DB_DNODE_ENTER(db); 2610 dn = DB_DNODE(db); 2611 ASSERT(list_head(&dr->dt.di.dr_children) == NULL); 2612 ASSERT3U(db->db.db_size, ==, 1 << dn->dn_phys->dn_indblkshift); 2613 if (!BP_IS_HOLE(db->db_blkptr)) { 2614 int epbs = 2615 dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT; 2616 ASSERT3U(db->db_blkid, <=, 2617 dn->dn_phys->dn_maxblkid >> (db->db_level * epbs)); 2618 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==, 2619 db->db.db_size); 2620 arc_set_callback(db->db_buf, dbuf_do_evict, db); 2621 } 2622 DB_DNODE_EXIT(db); 2623 mutex_destroy(&dr->dt.di.dr_mtx); 2624 list_destroy(&dr->dt.di.dr_children); 2625 } 2626 kmem_free(dr, sizeof (dbuf_dirty_record_t)); 2627 2628 cv_broadcast(&db->db_changed); 2629 ASSERT(db->db_dirtycnt > 0); 2630 db->db_dirtycnt -= 1; 2631 db->db_data_pending = NULL; 2632 dbuf_rele_and_unlock(db, (void *)(uintptr_t)tx->tx_txg); 2633 } 2634 2635 static void 2636 dbuf_write_nofill_ready(zio_t *zio) 2637 { 2638 dbuf_write_ready(zio, NULL, zio->io_private); 2639 } 2640 2641 static void 2642 dbuf_write_nofill_done(zio_t *zio) 2643 { 2644 dbuf_write_done(zio, NULL, zio->io_private); 2645 } 2646 2647 static void 2648 dbuf_write_override_ready(zio_t *zio) 2649 { 2650 dbuf_dirty_record_t *dr = zio->io_private; 2651 dmu_buf_impl_t *db = dr->dr_dbuf; 2652 2653 dbuf_write_ready(zio, NULL, db); 2654 } 2655 2656 static void 2657 dbuf_write_override_done(zio_t *zio) 2658 { 2659 dbuf_dirty_record_t *dr = zio->io_private; 2660 dmu_buf_impl_t *db = dr->dr_dbuf; 2661 blkptr_t *obp = &dr->dt.dl.dr_overridden_by; 2662 2663 mutex_enter(&db->db_mtx); 2664 if (!BP_EQUAL(zio->io_bp, obp)) { 2665 if (!BP_IS_HOLE(obp)) 2666 dsl_free(spa_get_dsl(zio->io_spa), zio->io_txg, obp); 2667 arc_release(dr->dt.dl.dr_data, db); 2668 } 2669 mutex_exit(&db->db_mtx); 2670 2671 dbuf_write_done(zio, NULL, db); 2672 } 2673 2674 /* Issue I/O to commit a dirty buffer to disk. */ 2675 static void 2676 dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx) 2677 { 2678 dmu_buf_impl_t *db = dr->dr_dbuf; 2679 dnode_t *dn; 2680 objset_t *os; 2681 dmu_buf_impl_t *parent = db->db_parent; 2682 uint64_t txg = tx->tx_txg; 2683 zbookmark_t zb; 2684 zio_prop_t zp; 2685 zio_t *zio; 2686 int wp_flag = 0; 2687 2688 DB_DNODE_ENTER(db); 2689 dn = DB_DNODE(db); 2690 os = dn->dn_objset; 2691 2692 if (db->db_state != DB_NOFILL) { 2693 if (db->db_level > 0 || dn->dn_type == DMU_OT_DNODE) { 2694 /* 2695 * Private object buffers are released here rather 2696 * than in dbuf_dirty() since they are only modified 2697 * in the syncing context and we don't want the 2698 * overhead of making multiple copies of the data. 2699 */ 2700 if (BP_IS_HOLE(db->db_blkptr)) { 2701 arc_buf_thaw(data); 2702 } else { 2703 dbuf_release_bp(db); 2704 } 2705 } 2706 } 2707 2708 if (parent != dn->dn_dbuf) { 2709 /* Our parent is an indirect block. */ 2710 /* We have a dirty parent that has been scheduled for write. */ 2711 ASSERT(parent && parent->db_data_pending); 2712 /* Our parent's buffer is one level closer to the dnode. */ 2713 ASSERT(db->db_level == parent->db_level-1); 2714 /* 2715 * We're about to modify our parent's db_data by modifying 2716 * our block pointer, so the parent must be released. 2717 */ 2718 ASSERT(arc_released(parent->db_buf)); 2719 zio = parent->db_data_pending->dr_zio; 2720 } else { 2721 /* Our parent is the dnode itself. */ 2722 ASSERT((db->db_level == dn->dn_phys->dn_nlevels-1 && 2723 db->db_blkid != DMU_SPILL_BLKID) || 2724 (db->db_blkid == DMU_SPILL_BLKID && db->db_level == 0)); 2725 if (db->db_blkid != DMU_SPILL_BLKID) 2726 ASSERT3P(db->db_blkptr, ==, 2727 &dn->dn_phys->dn_blkptr[db->db_blkid]); 2728 zio = dn->dn_zio; 2729 } 2730 2731 ASSERT(db->db_level == 0 || data == db->db_buf); 2732 ASSERT3U(db->db_blkptr->blk_birth, <=, txg); 2733 ASSERT(zio); 2734 2735 SET_BOOKMARK(&zb, os->os_dsl_dataset ? 2736 os->os_dsl_dataset->ds_object : DMU_META_OBJSET, 2737 db->db.db_object, db->db_level, db->db_blkid); 2738 2739 if (db->db_blkid == DMU_SPILL_BLKID) 2740 wp_flag = WP_SPILL; 2741 wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0; 2742 2743 dmu_write_policy(os, dn, db->db_level, wp_flag, &zp); 2744 DB_DNODE_EXIT(db); 2745 2746 if (db->db_level == 0 && dr->dt.dl.dr_override_state == DR_OVERRIDDEN) { 2747 ASSERT(db->db_state != DB_NOFILL); 2748 dr->dr_zio = zio_write(zio, os->os_spa, txg, 2749 db->db_blkptr, data->b_data, arc_buf_size(data), &zp, 2750 dbuf_write_override_ready, NULL, dbuf_write_override_done, 2751 dr, ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb); 2752 mutex_enter(&db->db_mtx); 2753 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN; 2754 zio_write_override(dr->dr_zio, &dr->dt.dl.dr_overridden_by, 2755 dr->dt.dl.dr_copies, dr->dt.dl.dr_nopwrite); 2756 mutex_exit(&db->db_mtx); 2757 } else if (db->db_state == DB_NOFILL) { 2758 ASSERT(zp.zp_checksum == ZIO_CHECKSUM_OFF || 2759 zp.zp_checksum == ZIO_CHECKSUM_NOPARITY); 2760 dr->dr_zio = zio_write(zio, os->os_spa, txg, 2761 db->db_blkptr, NULL, db->db.db_size, &zp, 2762 dbuf_write_nofill_ready, NULL, dbuf_write_nofill_done, db, 2763 ZIO_PRIORITY_ASYNC_WRITE, 2764 ZIO_FLAG_MUSTSUCCEED | ZIO_FLAG_NODATA, &zb); 2765 } else { 2766 ASSERT(arc_released(data)); 2767 dr->dr_zio = arc_write(zio, os->os_spa, txg, 2768 db->db_blkptr, data, DBUF_IS_L2CACHEABLE(db), 2769 DBUF_IS_L2COMPRESSIBLE(db), &zp, dbuf_write_ready, 2770 dbuf_write_physdone, dbuf_write_done, db, 2771 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb); 2772 } 2773 } 2774