1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. 23 * Copyright (c) 2011, 2017 by Delphix. All rights reserved. 24 * Copyright (c) 2014 Integros [integros.com] 25 */ 26 27 /* Portions Copyright 2010 Robert Milkowski */ 28 29 #include <sys/zfs_context.h> 30 #include <sys/spa.h> 31 #include <sys/dmu.h> 32 #include <sys/zap.h> 33 #include <sys/arc.h> 34 #include <sys/stat.h> 35 #include <sys/resource.h> 36 #include <sys/zil.h> 37 #include <sys/zil_impl.h> 38 #include <sys/dsl_dataset.h> 39 #include <sys/vdev_impl.h> 40 #include <sys/dmu_tx.h> 41 #include <sys/dsl_pool.h> 42 #include <sys/abd.h> 43 44 /* 45 * The ZFS Intent Log (ZIL) saves "transaction records" (itxs) of system 46 * calls that change the file system. Each itx has enough information to 47 * be able to replay them after a system crash, power loss, or 48 * equivalent failure mode. These are stored in memory until either: 49 * 50 * 1. they are committed to the pool by the DMU transaction group 51 * (txg), at which point they can be discarded; or 52 * 2. they are committed to the on-disk ZIL for the dataset being 53 * modified (e.g. due to an fsync, O_DSYNC, or other synchronous 54 * requirement). 55 * 56 * In the event of a crash or power loss, the itxs contained by each 57 * dataset's on-disk ZIL will be replayed when that dataset is first 58 * instantianted (e.g. if the dataset is a normal fileystem, when it is 59 * first mounted). 60 * 61 * As hinted at above, there is one ZIL per dataset (both the in-memory 62 * representation, and the on-disk representation). The on-disk format 63 * consists of 3 parts: 64 * 65 * - a single, per-dataset, ZIL header; which points to a chain of 66 * - zero or more ZIL blocks; each of which contains 67 * - zero or more ZIL records 68 * 69 * A ZIL record holds the information necessary to replay a single 70 * system call transaction. A ZIL block can hold many ZIL records, and 71 * the blocks are chained together, similarly to a singly linked list. 72 * 73 * Each ZIL block contains a block pointer (blkptr_t) to the next ZIL 74 * block in the chain, and the ZIL header points to the first block in 75 * the chain. 76 * 77 * Note, there is not a fixed place in the pool to hold these ZIL 78 * blocks; they are dynamically allocated and freed as needed from the 79 * blocks available on the pool, though they can be preferentially 80 * allocated from a dedicated "log" vdev. 81 */ 82 83 /* 84 * This controls the amount of time that a ZIL block (lwb) will remain 85 * "open" when it isn't "full", and it has a thread waiting for it to be 86 * committed to stable storage. Please refer to the zil_commit_waiter() 87 * function (and the comments within it) for more details. 88 */ 89 int zfs_commit_timeout_pct = 5; 90 91 /* 92 * Disable intent logging replay. This global ZIL switch affects all pools. 93 */ 94 int zil_replay_disable = 0; 95 96 /* 97 * Tunable parameter for debugging or performance analysis. Setting 98 * zfs_nocacheflush will cause corruption on power loss if a volatile 99 * out-of-order write cache is enabled. 100 */ 101 boolean_t zfs_nocacheflush = B_FALSE; 102 103 /* 104 * Limit SLOG write size per commit executed with synchronous priority. 105 * Any writes above that will be executed with lower (asynchronous) priority 106 * to limit potential SLOG device abuse by single active ZIL writer. 107 */ 108 uint64_t zil_slog_bulk = 768 * 1024; 109 110 static kmem_cache_t *zil_lwb_cache; 111 static kmem_cache_t *zil_zcw_cache; 112 113 static void zil_async_to_sync(zilog_t *zilog, uint64_t foid); 114 115 #define LWB_EMPTY(lwb) ((BP_GET_LSIZE(&lwb->lwb_blk) - \ 116 sizeof (zil_chain_t)) == (lwb->lwb_sz - lwb->lwb_nused)) 117 118 static int 119 zil_bp_compare(const void *x1, const void *x2) 120 { 121 const dva_t *dva1 = &((zil_bp_node_t *)x1)->zn_dva; 122 const dva_t *dva2 = &((zil_bp_node_t *)x2)->zn_dva; 123 124 if (DVA_GET_VDEV(dva1) < DVA_GET_VDEV(dva2)) 125 return (-1); 126 if (DVA_GET_VDEV(dva1) > DVA_GET_VDEV(dva2)) 127 return (1); 128 129 if (DVA_GET_OFFSET(dva1) < DVA_GET_OFFSET(dva2)) 130 return (-1); 131 if (DVA_GET_OFFSET(dva1) > DVA_GET_OFFSET(dva2)) 132 return (1); 133 134 return (0); 135 } 136 137 static void 138 zil_bp_tree_init(zilog_t *zilog) 139 { 140 avl_create(&zilog->zl_bp_tree, zil_bp_compare, 141 sizeof (zil_bp_node_t), offsetof(zil_bp_node_t, zn_node)); 142 } 143 144 static void 145 zil_bp_tree_fini(zilog_t *zilog) 146 { 147 avl_tree_t *t = &zilog->zl_bp_tree; 148 zil_bp_node_t *zn; 149 void *cookie = NULL; 150 151 while ((zn = avl_destroy_nodes(t, &cookie)) != NULL) 152 kmem_free(zn, sizeof (zil_bp_node_t)); 153 154 avl_destroy(t); 155 } 156 157 int 158 zil_bp_tree_add(zilog_t *zilog, const blkptr_t *bp) 159 { 160 avl_tree_t *t = &zilog->zl_bp_tree; 161 const dva_t *dva; 162 zil_bp_node_t *zn; 163 avl_index_t where; 164 165 if (BP_IS_EMBEDDED(bp)) 166 return (0); 167 168 dva = BP_IDENTITY(bp); 169 170 if (avl_find(t, dva, &where) != NULL) 171 return (SET_ERROR(EEXIST)); 172 173 zn = kmem_alloc(sizeof (zil_bp_node_t), KM_SLEEP); 174 zn->zn_dva = *dva; 175 avl_insert(t, zn, where); 176 177 return (0); 178 } 179 180 static zil_header_t * 181 zil_header_in_syncing_context(zilog_t *zilog) 182 { 183 return ((zil_header_t *)zilog->zl_header); 184 } 185 186 static void 187 zil_init_log_chain(zilog_t *zilog, blkptr_t *bp) 188 { 189 zio_cksum_t *zc = &bp->blk_cksum; 190 191 zc->zc_word[ZIL_ZC_GUID_0] = spa_get_random(-1ULL); 192 zc->zc_word[ZIL_ZC_GUID_1] = spa_get_random(-1ULL); 193 zc->zc_word[ZIL_ZC_OBJSET] = dmu_objset_id(zilog->zl_os); 194 zc->zc_word[ZIL_ZC_SEQ] = 1ULL; 195 } 196 197 /* 198 * Read a log block and make sure it's valid. 199 */ 200 static int 201 zil_read_log_block(zilog_t *zilog, const blkptr_t *bp, blkptr_t *nbp, void *dst, 202 char **end) 203 { 204 enum zio_flag zio_flags = ZIO_FLAG_CANFAIL; 205 arc_flags_t aflags = ARC_FLAG_WAIT; 206 arc_buf_t *abuf = NULL; 207 zbookmark_phys_t zb; 208 int error; 209 210 if (zilog->zl_header->zh_claim_txg == 0) 211 zio_flags |= ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SCRUB; 212 213 if (!(zilog->zl_header->zh_flags & ZIL_CLAIM_LR_SEQ_VALID)) 214 zio_flags |= ZIO_FLAG_SPECULATIVE; 215 216 SET_BOOKMARK(&zb, bp->blk_cksum.zc_word[ZIL_ZC_OBJSET], 217 ZB_ZIL_OBJECT, ZB_ZIL_LEVEL, bp->blk_cksum.zc_word[ZIL_ZC_SEQ]); 218 219 error = arc_read(NULL, zilog->zl_spa, bp, arc_getbuf_func, &abuf, 220 ZIO_PRIORITY_SYNC_READ, zio_flags, &aflags, &zb); 221 222 if (error == 0) { 223 zio_cksum_t cksum = bp->blk_cksum; 224 225 /* 226 * Validate the checksummed log block. 227 * 228 * Sequence numbers should be... sequential. The checksum 229 * verifier for the next block should be bp's checksum plus 1. 230 * 231 * Also check the log chain linkage and size used. 232 */ 233 cksum.zc_word[ZIL_ZC_SEQ]++; 234 235 if (BP_GET_CHECKSUM(bp) == ZIO_CHECKSUM_ZILOG2) { 236 zil_chain_t *zilc = abuf->b_data; 237 char *lr = (char *)(zilc + 1); 238 uint64_t len = zilc->zc_nused - sizeof (zil_chain_t); 239 240 if (bcmp(&cksum, &zilc->zc_next_blk.blk_cksum, 241 sizeof (cksum)) || BP_IS_HOLE(&zilc->zc_next_blk)) { 242 error = SET_ERROR(ECKSUM); 243 } else { 244 ASSERT3U(len, <=, SPA_OLD_MAXBLOCKSIZE); 245 bcopy(lr, dst, len); 246 *end = (char *)dst + len; 247 *nbp = zilc->zc_next_blk; 248 } 249 } else { 250 char *lr = abuf->b_data; 251 uint64_t size = BP_GET_LSIZE(bp); 252 zil_chain_t *zilc = (zil_chain_t *)(lr + size) - 1; 253 254 if (bcmp(&cksum, &zilc->zc_next_blk.blk_cksum, 255 sizeof (cksum)) || BP_IS_HOLE(&zilc->zc_next_blk) || 256 (zilc->zc_nused > (size - sizeof (*zilc)))) { 257 error = SET_ERROR(ECKSUM); 258 } else { 259 ASSERT3U(zilc->zc_nused, <=, 260 SPA_OLD_MAXBLOCKSIZE); 261 bcopy(lr, dst, zilc->zc_nused); 262 *end = (char *)dst + zilc->zc_nused; 263 *nbp = zilc->zc_next_blk; 264 } 265 } 266 267 arc_buf_destroy(abuf, &abuf); 268 } 269 270 return (error); 271 } 272 273 /* 274 * Read a TX_WRITE log data block. 275 */ 276 static int 277 zil_read_log_data(zilog_t *zilog, const lr_write_t *lr, void *wbuf) 278 { 279 enum zio_flag zio_flags = ZIO_FLAG_CANFAIL; 280 const blkptr_t *bp = &lr->lr_blkptr; 281 arc_flags_t aflags = ARC_FLAG_WAIT; 282 arc_buf_t *abuf = NULL; 283 zbookmark_phys_t zb; 284 int error; 285 286 if (BP_IS_HOLE(bp)) { 287 if (wbuf != NULL) 288 bzero(wbuf, MAX(BP_GET_LSIZE(bp), lr->lr_length)); 289 return (0); 290 } 291 292 if (zilog->zl_header->zh_claim_txg == 0) 293 zio_flags |= ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SCRUB; 294 295 SET_BOOKMARK(&zb, dmu_objset_id(zilog->zl_os), lr->lr_foid, 296 ZB_ZIL_LEVEL, lr->lr_offset / BP_GET_LSIZE(bp)); 297 298 error = arc_read(NULL, zilog->zl_spa, bp, arc_getbuf_func, &abuf, 299 ZIO_PRIORITY_SYNC_READ, zio_flags, &aflags, &zb); 300 301 if (error == 0) { 302 if (wbuf != NULL) 303 bcopy(abuf->b_data, wbuf, arc_buf_size(abuf)); 304 arc_buf_destroy(abuf, &abuf); 305 } 306 307 return (error); 308 } 309 310 /* 311 * Parse the intent log, and call parse_func for each valid record within. 312 */ 313 int 314 zil_parse(zilog_t *zilog, zil_parse_blk_func_t *parse_blk_func, 315 zil_parse_lr_func_t *parse_lr_func, void *arg, uint64_t txg) 316 { 317 const zil_header_t *zh = zilog->zl_header; 318 boolean_t claimed = !!zh->zh_claim_txg; 319 uint64_t claim_blk_seq = claimed ? zh->zh_claim_blk_seq : UINT64_MAX; 320 uint64_t claim_lr_seq = claimed ? zh->zh_claim_lr_seq : UINT64_MAX; 321 uint64_t max_blk_seq = 0; 322 uint64_t max_lr_seq = 0; 323 uint64_t blk_count = 0; 324 uint64_t lr_count = 0; 325 blkptr_t blk, next_blk; 326 char *lrbuf, *lrp; 327 int error = 0; 328 329 /* 330 * Old logs didn't record the maximum zh_claim_lr_seq. 331 */ 332 if (!(zh->zh_flags & ZIL_CLAIM_LR_SEQ_VALID)) 333 claim_lr_seq = UINT64_MAX; 334 335 /* 336 * Starting at the block pointed to by zh_log we read the log chain. 337 * For each block in the chain we strongly check that block to 338 * ensure its validity. We stop when an invalid block is found. 339 * For each block pointer in the chain we call parse_blk_func(). 340 * For each record in each valid block we call parse_lr_func(). 341 * If the log has been claimed, stop if we encounter a sequence 342 * number greater than the highest claimed sequence number. 343 */ 344 lrbuf = zio_buf_alloc(SPA_OLD_MAXBLOCKSIZE); 345 zil_bp_tree_init(zilog); 346 347 for (blk = zh->zh_log; !BP_IS_HOLE(&blk); blk = next_blk) { 348 uint64_t blk_seq = blk.blk_cksum.zc_word[ZIL_ZC_SEQ]; 349 int reclen; 350 char *end; 351 352 if (blk_seq > claim_blk_seq) 353 break; 354 if ((error = parse_blk_func(zilog, &blk, arg, txg)) != 0) 355 break; 356 ASSERT3U(max_blk_seq, <, blk_seq); 357 max_blk_seq = blk_seq; 358 blk_count++; 359 360 if (max_lr_seq == claim_lr_seq && max_blk_seq == claim_blk_seq) 361 break; 362 363 error = zil_read_log_block(zilog, &blk, &next_blk, lrbuf, &end); 364 if (error != 0) 365 break; 366 367 for (lrp = lrbuf; lrp < end; lrp += reclen) { 368 lr_t *lr = (lr_t *)lrp; 369 reclen = lr->lrc_reclen; 370 ASSERT3U(reclen, >=, sizeof (lr_t)); 371 if (lr->lrc_seq > claim_lr_seq) 372 goto done; 373 if ((error = parse_lr_func(zilog, lr, arg, txg)) != 0) 374 goto done; 375 ASSERT3U(max_lr_seq, <, lr->lrc_seq); 376 max_lr_seq = lr->lrc_seq; 377 lr_count++; 378 } 379 } 380 done: 381 zilog->zl_parse_error = error; 382 zilog->zl_parse_blk_seq = max_blk_seq; 383 zilog->zl_parse_lr_seq = max_lr_seq; 384 zilog->zl_parse_blk_count = blk_count; 385 zilog->zl_parse_lr_count = lr_count; 386 387 ASSERT(!claimed || !(zh->zh_flags & ZIL_CLAIM_LR_SEQ_VALID) || 388 (max_blk_seq == claim_blk_seq && max_lr_seq == claim_lr_seq)); 389 390 zil_bp_tree_fini(zilog); 391 zio_buf_free(lrbuf, SPA_OLD_MAXBLOCKSIZE); 392 393 return (error); 394 } 395 396 static int 397 zil_claim_log_block(zilog_t *zilog, blkptr_t *bp, void *tx, uint64_t first_txg) 398 { 399 /* 400 * Claim log block if not already committed and not already claimed. 401 * If tx == NULL, just verify that the block is claimable. 402 */ 403 if (BP_IS_HOLE(bp) || bp->blk_birth < first_txg || 404 zil_bp_tree_add(zilog, bp) != 0) 405 return (0); 406 407 return (zio_wait(zio_claim(NULL, zilog->zl_spa, 408 tx == NULL ? 0 : first_txg, bp, spa_claim_notify, NULL, 409 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SCRUB))); 410 } 411 412 static int 413 zil_claim_log_record(zilog_t *zilog, lr_t *lrc, void *tx, uint64_t first_txg) 414 { 415 lr_write_t *lr = (lr_write_t *)lrc; 416 int error; 417 418 if (lrc->lrc_txtype != TX_WRITE) 419 return (0); 420 421 /* 422 * If the block is not readable, don't claim it. This can happen 423 * in normal operation when a log block is written to disk before 424 * some of the dmu_sync() blocks it points to. In this case, the 425 * transaction cannot have been committed to anyone (we would have 426 * waited for all writes to be stable first), so it is semantically 427 * correct to declare this the end of the log. 428 */ 429 if (lr->lr_blkptr.blk_birth >= first_txg && 430 (error = zil_read_log_data(zilog, lr, NULL)) != 0) 431 return (error); 432 return (zil_claim_log_block(zilog, &lr->lr_blkptr, tx, first_txg)); 433 } 434 435 /* ARGSUSED */ 436 static int 437 zil_free_log_block(zilog_t *zilog, blkptr_t *bp, void *tx, uint64_t claim_txg) 438 { 439 zio_free_zil(zilog->zl_spa, dmu_tx_get_txg(tx), bp); 440 441 return (0); 442 } 443 444 static int 445 zil_free_log_record(zilog_t *zilog, lr_t *lrc, void *tx, uint64_t claim_txg) 446 { 447 lr_write_t *lr = (lr_write_t *)lrc; 448 blkptr_t *bp = &lr->lr_blkptr; 449 450 /* 451 * If we previously claimed it, we need to free it. 452 */ 453 if (claim_txg != 0 && lrc->lrc_txtype == TX_WRITE && 454 bp->blk_birth >= claim_txg && zil_bp_tree_add(zilog, bp) == 0 && 455 !BP_IS_HOLE(bp)) 456 zio_free(zilog->zl_spa, dmu_tx_get_txg(tx), bp); 457 458 return (0); 459 } 460 461 static int 462 zil_lwb_vdev_compare(const void *x1, const void *x2) 463 { 464 const uint64_t v1 = ((zil_vdev_node_t *)x1)->zv_vdev; 465 const uint64_t v2 = ((zil_vdev_node_t *)x2)->zv_vdev; 466 467 if (v1 < v2) 468 return (-1); 469 if (v1 > v2) 470 return (1); 471 472 return (0); 473 } 474 475 static lwb_t * 476 zil_alloc_lwb(zilog_t *zilog, blkptr_t *bp, boolean_t slog, uint64_t txg) 477 { 478 lwb_t *lwb; 479 480 lwb = kmem_cache_alloc(zil_lwb_cache, KM_SLEEP); 481 lwb->lwb_zilog = zilog; 482 lwb->lwb_blk = *bp; 483 lwb->lwb_slog = slog; 484 lwb->lwb_state = LWB_STATE_CLOSED; 485 lwb->lwb_buf = zio_buf_alloc(BP_GET_LSIZE(bp)); 486 lwb->lwb_max_txg = txg; 487 lwb->lwb_write_zio = NULL; 488 lwb->lwb_root_zio = NULL; 489 lwb->lwb_tx = NULL; 490 lwb->lwb_issued_timestamp = 0; 491 if (BP_GET_CHECKSUM(bp) == ZIO_CHECKSUM_ZILOG2) { 492 lwb->lwb_nused = sizeof (zil_chain_t); 493 lwb->lwb_sz = BP_GET_LSIZE(bp); 494 } else { 495 lwb->lwb_nused = 0; 496 lwb->lwb_sz = BP_GET_LSIZE(bp) - sizeof (zil_chain_t); 497 } 498 499 mutex_enter(&zilog->zl_lock); 500 list_insert_tail(&zilog->zl_lwb_list, lwb); 501 mutex_exit(&zilog->zl_lock); 502 503 ASSERT(!MUTEX_HELD(&lwb->lwb_vdev_lock)); 504 ASSERT(avl_is_empty(&lwb->lwb_vdev_tree)); 505 VERIFY(list_is_empty(&lwb->lwb_waiters)); 506 507 return (lwb); 508 } 509 510 static void 511 zil_free_lwb(zilog_t *zilog, lwb_t *lwb) 512 { 513 ASSERT(MUTEX_HELD(&zilog->zl_lock)); 514 ASSERT(!MUTEX_HELD(&lwb->lwb_vdev_lock)); 515 VERIFY(list_is_empty(&lwb->lwb_waiters)); 516 ASSERT(avl_is_empty(&lwb->lwb_vdev_tree)); 517 ASSERT3P(lwb->lwb_write_zio, ==, NULL); 518 ASSERT3P(lwb->lwb_root_zio, ==, NULL); 519 ASSERT3U(lwb->lwb_max_txg, <=, spa_syncing_txg(zilog->zl_spa)); 520 ASSERT(lwb->lwb_state == LWB_STATE_CLOSED || 521 lwb->lwb_state == LWB_STATE_DONE); 522 523 /* 524 * Clear the zilog's field to indicate this lwb is no longer 525 * valid, and prevent use-after-free errors. 526 */ 527 if (zilog->zl_last_lwb_opened == lwb) 528 zilog->zl_last_lwb_opened = NULL; 529 530 kmem_cache_free(zil_lwb_cache, lwb); 531 } 532 533 /* 534 * Called when we create in-memory log transactions so that we know 535 * to cleanup the itxs at the end of spa_sync(). 536 */ 537 void 538 zilog_dirty(zilog_t *zilog, uint64_t txg) 539 { 540 dsl_pool_t *dp = zilog->zl_dmu_pool; 541 dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os); 542 543 ASSERT(spa_writeable(zilog->zl_spa)); 544 545 if (ds->ds_is_snapshot) 546 panic("dirtying snapshot!"); 547 548 if (txg_list_add(&dp->dp_dirty_zilogs, zilog, txg)) { 549 /* up the hold count until we can be written out */ 550 dmu_buf_add_ref(ds->ds_dbuf, zilog); 551 552 zilog->zl_dirty_max_txg = MAX(txg, zilog->zl_dirty_max_txg); 553 } 554 } 555 556 /* 557 * Determine if the zil is dirty in the specified txg. Callers wanting to 558 * ensure that the dirty state does not change must hold the itxg_lock for 559 * the specified txg. Holding the lock will ensure that the zil cannot be 560 * dirtied (zil_itx_assign) or cleaned (zil_clean) while we check its current 561 * state. 562 */ 563 boolean_t 564 zilog_is_dirty_in_txg(zilog_t *zilog, uint64_t txg) 565 { 566 dsl_pool_t *dp = zilog->zl_dmu_pool; 567 568 if (txg_list_member(&dp->dp_dirty_zilogs, zilog, txg & TXG_MASK)) 569 return (B_TRUE); 570 return (B_FALSE); 571 } 572 573 /* 574 * Determine if the zil is dirty. The zil is considered dirty if it has 575 * any pending itx records that have not been cleaned by zil_clean(). 576 */ 577 boolean_t 578 zilog_is_dirty(zilog_t *zilog) 579 { 580 dsl_pool_t *dp = zilog->zl_dmu_pool; 581 582 for (int t = 0; t < TXG_SIZE; t++) { 583 if (txg_list_member(&dp->dp_dirty_zilogs, zilog, t)) 584 return (B_TRUE); 585 } 586 return (B_FALSE); 587 } 588 589 /* 590 * Create an on-disk intent log. 591 */ 592 static lwb_t * 593 zil_create(zilog_t *zilog) 594 { 595 const zil_header_t *zh = zilog->zl_header; 596 lwb_t *lwb = NULL; 597 uint64_t txg = 0; 598 dmu_tx_t *tx = NULL; 599 blkptr_t blk; 600 int error = 0; 601 boolean_t slog = FALSE; 602 603 /* 604 * Wait for any previous destroy to complete. 605 */ 606 txg_wait_synced(zilog->zl_dmu_pool, zilog->zl_destroy_txg); 607 608 ASSERT(zh->zh_claim_txg == 0); 609 ASSERT(zh->zh_replay_seq == 0); 610 611 blk = zh->zh_log; 612 613 /* 614 * Allocate an initial log block if: 615 * - there isn't one already 616 * - the existing block is the wrong endianess 617 */ 618 if (BP_IS_HOLE(&blk) || BP_SHOULD_BYTESWAP(&blk)) { 619 tx = dmu_tx_create(zilog->zl_os); 620 VERIFY0(dmu_tx_assign(tx, TXG_WAIT)); 621 dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx); 622 txg = dmu_tx_get_txg(tx); 623 624 if (!BP_IS_HOLE(&blk)) { 625 zio_free_zil(zilog->zl_spa, txg, &blk); 626 BP_ZERO(&blk); 627 } 628 629 error = zio_alloc_zil(zilog->zl_spa, txg, &blk, NULL, 630 ZIL_MIN_BLKSZ, &slog); 631 632 if (error == 0) 633 zil_init_log_chain(zilog, &blk); 634 } 635 636 /* 637 * Allocate a log write block (lwb) for the first log block. 638 */ 639 if (error == 0) 640 lwb = zil_alloc_lwb(zilog, &blk, slog, txg); 641 642 /* 643 * If we just allocated the first log block, commit our transaction 644 * and wait for zil_sync() to stuff the block poiner into zh_log. 645 * (zh is part of the MOS, so we cannot modify it in open context.) 646 */ 647 if (tx != NULL) { 648 dmu_tx_commit(tx); 649 txg_wait_synced(zilog->zl_dmu_pool, txg); 650 } 651 652 ASSERT(bcmp(&blk, &zh->zh_log, sizeof (blk)) == 0); 653 654 return (lwb); 655 } 656 657 /* 658 * In one tx, free all log blocks and clear the log header. If keep_first 659 * is set, then we're replaying a log with no content. We want to keep the 660 * first block, however, so that the first synchronous transaction doesn't 661 * require a txg_wait_synced() in zil_create(). We don't need to 662 * txg_wait_synced() here either when keep_first is set, because both 663 * zil_create() and zil_destroy() will wait for any in-progress destroys 664 * to complete. 665 */ 666 void 667 zil_destroy(zilog_t *zilog, boolean_t keep_first) 668 { 669 const zil_header_t *zh = zilog->zl_header; 670 lwb_t *lwb; 671 dmu_tx_t *tx; 672 uint64_t txg; 673 674 /* 675 * Wait for any previous destroy to complete. 676 */ 677 txg_wait_synced(zilog->zl_dmu_pool, zilog->zl_destroy_txg); 678 679 zilog->zl_old_header = *zh; /* debugging aid */ 680 681 if (BP_IS_HOLE(&zh->zh_log)) 682 return; 683 684 tx = dmu_tx_create(zilog->zl_os); 685 VERIFY0(dmu_tx_assign(tx, TXG_WAIT)); 686 dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx); 687 txg = dmu_tx_get_txg(tx); 688 689 mutex_enter(&zilog->zl_lock); 690 691 ASSERT3U(zilog->zl_destroy_txg, <, txg); 692 zilog->zl_destroy_txg = txg; 693 zilog->zl_keep_first = keep_first; 694 695 if (!list_is_empty(&zilog->zl_lwb_list)) { 696 ASSERT(zh->zh_claim_txg == 0); 697 VERIFY(!keep_first); 698 while ((lwb = list_head(&zilog->zl_lwb_list)) != NULL) { 699 list_remove(&zilog->zl_lwb_list, lwb); 700 if (lwb->lwb_buf != NULL) 701 zio_buf_free(lwb->lwb_buf, lwb->lwb_sz); 702 zio_free(zilog->zl_spa, txg, &lwb->lwb_blk); 703 zil_free_lwb(zilog, lwb); 704 } 705 } else if (!keep_first) { 706 zil_destroy_sync(zilog, tx); 707 } 708 mutex_exit(&zilog->zl_lock); 709 710 dmu_tx_commit(tx); 711 } 712 713 void 714 zil_destroy_sync(zilog_t *zilog, dmu_tx_t *tx) 715 { 716 ASSERT(list_is_empty(&zilog->zl_lwb_list)); 717 (void) zil_parse(zilog, zil_free_log_block, 718 zil_free_log_record, tx, zilog->zl_header->zh_claim_txg); 719 } 720 721 int 722 zil_claim(dsl_pool_t *dp, dsl_dataset_t *ds, void *txarg) 723 { 724 dmu_tx_t *tx = txarg; 725 uint64_t first_txg = dmu_tx_get_txg(tx); 726 zilog_t *zilog; 727 zil_header_t *zh; 728 objset_t *os; 729 int error; 730 731 error = dmu_objset_own_obj(dp, ds->ds_object, 732 DMU_OST_ANY, B_FALSE, FTAG, &os); 733 if (error != 0) { 734 /* 735 * EBUSY indicates that the objset is inconsistent, in which 736 * case it can not have a ZIL. 737 */ 738 if (error != EBUSY) { 739 cmn_err(CE_WARN, "can't open objset for %llu, error %u", 740 (unsigned long long)ds->ds_object, error); 741 } 742 return (0); 743 } 744 745 zilog = dmu_objset_zil(os); 746 zh = zil_header_in_syncing_context(zilog); 747 748 if (spa_get_log_state(zilog->zl_spa) == SPA_LOG_CLEAR) { 749 if (!BP_IS_HOLE(&zh->zh_log)) 750 zio_free_zil(zilog->zl_spa, first_txg, &zh->zh_log); 751 BP_ZERO(&zh->zh_log); 752 dsl_dataset_dirty(dmu_objset_ds(os), tx); 753 dmu_objset_disown(os, FTAG); 754 return (0); 755 } 756 757 /* 758 * Claim all log blocks if we haven't already done so, and remember 759 * the highest claimed sequence number. This ensures that if we can 760 * read only part of the log now (e.g. due to a missing device), 761 * but we can read the entire log later, we will not try to replay 762 * or destroy beyond the last block we successfully claimed. 763 */ 764 ASSERT3U(zh->zh_claim_txg, <=, first_txg); 765 if (zh->zh_claim_txg == 0 && !BP_IS_HOLE(&zh->zh_log)) { 766 (void) zil_parse(zilog, zil_claim_log_block, 767 zil_claim_log_record, tx, first_txg); 768 zh->zh_claim_txg = first_txg; 769 zh->zh_claim_blk_seq = zilog->zl_parse_blk_seq; 770 zh->zh_claim_lr_seq = zilog->zl_parse_lr_seq; 771 if (zilog->zl_parse_lr_count || zilog->zl_parse_blk_count > 1) 772 zh->zh_flags |= ZIL_REPLAY_NEEDED; 773 zh->zh_flags |= ZIL_CLAIM_LR_SEQ_VALID; 774 dsl_dataset_dirty(dmu_objset_ds(os), tx); 775 } 776 777 ASSERT3U(first_txg, ==, (spa_last_synced_txg(zilog->zl_spa) + 1)); 778 dmu_objset_disown(os, FTAG); 779 return (0); 780 } 781 782 /* 783 * Check the log by walking the log chain. 784 * Checksum errors are ok as they indicate the end of the chain. 785 * Any other error (no device or read failure) returns an error. 786 */ 787 /* ARGSUSED */ 788 int 789 zil_check_log_chain(dsl_pool_t *dp, dsl_dataset_t *ds, void *tx) 790 { 791 zilog_t *zilog; 792 objset_t *os; 793 blkptr_t *bp; 794 int error; 795 796 ASSERT(tx == NULL); 797 798 error = dmu_objset_from_ds(ds, &os); 799 if (error != 0) { 800 cmn_err(CE_WARN, "can't open objset %llu, error %d", 801 (unsigned long long)ds->ds_object, error); 802 return (0); 803 } 804 805 zilog = dmu_objset_zil(os); 806 bp = (blkptr_t *)&zilog->zl_header->zh_log; 807 808 /* 809 * Check the first block and determine if it's on a log device 810 * which may have been removed or faulted prior to loading this 811 * pool. If so, there's no point in checking the rest of the log 812 * as its content should have already been synced to the pool. 813 */ 814 if (!BP_IS_HOLE(bp)) { 815 vdev_t *vd; 816 boolean_t valid = B_TRUE; 817 818 spa_config_enter(os->os_spa, SCL_STATE, FTAG, RW_READER); 819 vd = vdev_lookup_top(os->os_spa, DVA_GET_VDEV(&bp->blk_dva[0])); 820 if (vd->vdev_islog && vdev_is_dead(vd)) 821 valid = vdev_log_state_valid(vd); 822 spa_config_exit(os->os_spa, SCL_STATE, FTAG); 823 824 if (!valid) 825 return (0); 826 } 827 828 /* 829 * Because tx == NULL, zil_claim_log_block() will not actually claim 830 * any blocks, but just determine whether it is possible to do so. 831 * In addition to checking the log chain, zil_claim_log_block() 832 * will invoke zio_claim() with a done func of spa_claim_notify(), 833 * which will update spa_max_claim_txg. See spa_load() for details. 834 */ 835 error = zil_parse(zilog, zil_claim_log_block, zil_claim_log_record, tx, 836 zilog->zl_header->zh_claim_txg ? -1ULL : spa_first_txg(os->os_spa)); 837 838 return ((error == ECKSUM || error == ENOENT) ? 0 : error); 839 } 840 841 /* 842 * When an itx is "skipped", this function is used to properly mark the 843 * waiter as "done, and signal any thread(s) waiting on it. An itx can 844 * be skipped (and not committed to an lwb) for a variety of reasons, 845 * one of them being that the itx was committed via spa_sync(), prior to 846 * it being committed to an lwb; this can happen if a thread calling 847 * zil_commit() is racing with spa_sync(). 848 */ 849 static void 850 zil_commit_waiter_skip(zil_commit_waiter_t *zcw) 851 { 852 mutex_enter(&zcw->zcw_lock); 853 ASSERT3B(zcw->zcw_done, ==, B_FALSE); 854 zcw->zcw_done = B_TRUE; 855 cv_broadcast(&zcw->zcw_cv); 856 mutex_exit(&zcw->zcw_lock); 857 } 858 859 /* 860 * This function is used when the given waiter is to be linked into an 861 * lwb's "lwb_waiter" list; i.e. when the itx is committed to the lwb. 862 * At this point, the waiter will no longer be referenced by the itx, 863 * and instead, will be referenced by the lwb. 864 */ 865 static void 866 zil_commit_waiter_link_lwb(zil_commit_waiter_t *zcw, lwb_t *lwb) 867 { 868 /* 869 * The lwb_waiters field of the lwb is protected by the zilog's 870 * zl_lock, thus it must be held when calling this function. 871 */ 872 ASSERT(MUTEX_HELD(&lwb->lwb_zilog->zl_lock)); 873 874 mutex_enter(&zcw->zcw_lock); 875 ASSERT(!list_link_active(&zcw->zcw_node)); 876 ASSERT3P(zcw->zcw_lwb, ==, NULL); 877 ASSERT3P(lwb, !=, NULL); 878 ASSERT(lwb->lwb_state == LWB_STATE_OPENED || 879 lwb->lwb_state == LWB_STATE_ISSUED); 880 881 list_insert_tail(&lwb->lwb_waiters, zcw); 882 zcw->zcw_lwb = lwb; 883 mutex_exit(&zcw->zcw_lock); 884 } 885 886 /* 887 * This function is used when zio_alloc_zil() fails to allocate a ZIL 888 * block, and the given waiter must be linked to the "nolwb waiters" 889 * list inside of zil_process_commit_list(). 890 */ 891 static void 892 zil_commit_waiter_link_nolwb(zil_commit_waiter_t *zcw, list_t *nolwb) 893 { 894 mutex_enter(&zcw->zcw_lock); 895 ASSERT(!list_link_active(&zcw->zcw_node)); 896 ASSERT3P(zcw->zcw_lwb, ==, NULL); 897 list_insert_tail(nolwb, zcw); 898 mutex_exit(&zcw->zcw_lock); 899 } 900 901 void 902 zil_lwb_add_block(lwb_t *lwb, const blkptr_t *bp) 903 { 904 avl_tree_t *t = &lwb->lwb_vdev_tree; 905 avl_index_t where; 906 zil_vdev_node_t *zv, zvsearch; 907 int ndvas = BP_GET_NDVAS(bp); 908 int i; 909 910 if (zfs_nocacheflush) 911 return; 912 913 mutex_enter(&lwb->lwb_vdev_lock); 914 for (i = 0; i < ndvas; i++) { 915 zvsearch.zv_vdev = DVA_GET_VDEV(&bp->blk_dva[i]); 916 if (avl_find(t, &zvsearch, &where) == NULL) { 917 zv = kmem_alloc(sizeof (*zv), KM_SLEEP); 918 zv->zv_vdev = zvsearch.zv_vdev; 919 avl_insert(t, zv, where); 920 } 921 } 922 mutex_exit(&lwb->lwb_vdev_lock); 923 } 924 925 void 926 zil_lwb_add_txg(lwb_t *lwb, uint64_t txg) 927 { 928 lwb->lwb_max_txg = MAX(lwb->lwb_max_txg, txg); 929 } 930 931 /* 932 * This function is a called after all VDEVs associated with a given lwb 933 * write have completed their DKIOCFLUSHWRITECACHE command; or as soon 934 * as the lwb write completes, if "zfs_nocacheflush" is set. 935 * 936 * The intention is for this function to be called as soon as the 937 * contents of an lwb are considered "stable" on disk, and will survive 938 * any sudden loss of power. At this point, any threads waiting for the 939 * lwb to reach this state are signalled, and the "waiter" structures 940 * are marked "done". 941 */ 942 static void 943 zil_lwb_flush_vdevs_done(zio_t *zio) 944 { 945 lwb_t *lwb = zio->io_private; 946 zilog_t *zilog = lwb->lwb_zilog; 947 dmu_tx_t *tx = lwb->lwb_tx; 948 zil_commit_waiter_t *zcw; 949 950 spa_config_exit(zilog->zl_spa, SCL_STATE, lwb); 951 952 zio_buf_free(lwb->lwb_buf, lwb->lwb_sz); 953 954 mutex_enter(&zilog->zl_lock); 955 956 /* 957 * Ensure the lwb buffer pointer is cleared before releasing the 958 * txg. If we have had an allocation failure and the txg is 959 * waiting to sync then we want zil_sync() to remove the lwb so 960 * that it's not picked up as the next new one in 961 * zil_process_commit_list(). zil_sync() will only remove the 962 * lwb if lwb_buf is null. 963 */ 964 lwb->lwb_buf = NULL; 965 lwb->lwb_tx = NULL; 966 967 ASSERT3U(lwb->lwb_issued_timestamp, >, 0); 968 zilog->zl_last_lwb_latency = gethrtime() - lwb->lwb_issued_timestamp; 969 970 lwb->lwb_root_zio = NULL; 971 lwb->lwb_state = LWB_STATE_DONE; 972 973 if (zilog->zl_last_lwb_opened == lwb) { 974 /* 975 * Remember the highest committed log sequence number 976 * for ztest. We only update this value when all the log 977 * writes succeeded, because ztest wants to ASSERT that 978 * it got the whole log chain. 979 */ 980 zilog->zl_commit_lr_seq = zilog->zl_lr_seq; 981 } 982 983 while ((zcw = list_head(&lwb->lwb_waiters)) != NULL) { 984 mutex_enter(&zcw->zcw_lock); 985 986 ASSERT(list_link_active(&zcw->zcw_node)); 987 list_remove(&lwb->lwb_waiters, zcw); 988 989 ASSERT3P(zcw->zcw_lwb, ==, lwb); 990 zcw->zcw_lwb = NULL; 991 992 zcw->zcw_zio_error = zio->io_error; 993 994 ASSERT3B(zcw->zcw_done, ==, B_FALSE); 995 zcw->zcw_done = B_TRUE; 996 cv_broadcast(&zcw->zcw_cv); 997 998 mutex_exit(&zcw->zcw_lock); 999 } 1000 1001 mutex_exit(&zilog->zl_lock); 1002 1003 /* 1004 * Now that we've written this log block, we have a stable pointer 1005 * to the next block in the chain, so it's OK to let the txg in 1006 * which we allocated the next block sync. 1007 */ 1008 dmu_tx_commit(tx); 1009 } 1010 1011 /* 1012 * This is called when an lwb write completes. This means, this specific 1013 * lwb was written to disk, and all dependent lwb have also been 1014 * written to disk. 1015 * 1016 * At this point, a DKIOCFLUSHWRITECACHE command hasn't been issued to 1017 * the VDEVs involved in writing out this specific lwb. The lwb will be 1018 * "done" once zil_lwb_flush_vdevs_done() is called, which occurs in the 1019 * zio completion callback for the lwb's root zio. 1020 */ 1021 static void 1022 zil_lwb_write_done(zio_t *zio) 1023 { 1024 lwb_t *lwb = zio->io_private; 1025 spa_t *spa = zio->io_spa; 1026 zilog_t *zilog = lwb->lwb_zilog; 1027 avl_tree_t *t = &lwb->lwb_vdev_tree; 1028 void *cookie = NULL; 1029 zil_vdev_node_t *zv; 1030 1031 ASSERT3S(spa_config_held(spa, SCL_STATE, RW_READER), !=, 0); 1032 1033 ASSERT(BP_GET_COMPRESS(zio->io_bp) == ZIO_COMPRESS_OFF); 1034 ASSERT(BP_GET_TYPE(zio->io_bp) == DMU_OT_INTENT_LOG); 1035 ASSERT(BP_GET_LEVEL(zio->io_bp) == 0); 1036 ASSERT(BP_GET_BYTEORDER(zio->io_bp) == ZFS_HOST_BYTEORDER); 1037 ASSERT(!BP_IS_GANG(zio->io_bp)); 1038 ASSERT(!BP_IS_HOLE(zio->io_bp)); 1039 ASSERT(BP_GET_FILL(zio->io_bp) == 0); 1040 1041 abd_put(zio->io_abd); 1042 1043 ASSERT3S(lwb->lwb_state, ==, LWB_STATE_ISSUED); 1044 1045 mutex_enter(&zilog->zl_lock); 1046 lwb->lwb_write_zio = NULL; 1047 mutex_exit(&zilog->zl_lock); 1048 1049 if (avl_numnodes(t) == 0) 1050 return; 1051 1052 /* 1053 * If there was an IO error, we're not going to call zio_flush() 1054 * on these vdevs, so we simply empty the tree and free the 1055 * nodes. We avoid calling zio_flush() since there isn't any 1056 * good reason for doing so, after the lwb block failed to be 1057 * written out. 1058 */ 1059 if (zio->io_error != 0) { 1060 while ((zv = avl_destroy_nodes(t, &cookie)) != NULL) 1061 kmem_free(zv, sizeof (*zv)); 1062 return; 1063 } 1064 1065 while ((zv = avl_destroy_nodes(t, &cookie)) != NULL) { 1066 vdev_t *vd = vdev_lookup_top(spa, zv->zv_vdev); 1067 if (vd != NULL) 1068 zio_flush(lwb->lwb_root_zio, vd); 1069 kmem_free(zv, sizeof (*zv)); 1070 } 1071 } 1072 1073 /* 1074 * This function's purpose is to "open" an lwb such that it is ready to 1075 * accept new itxs being committed to it. To do this, the lwb's zio 1076 * structures are created, and linked to the lwb. This function is 1077 * idempotent; if the passed in lwb has already been opened, this 1078 * function is essentially a no-op. 1079 */ 1080 static void 1081 zil_lwb_write_open(zilog_t *zilog, lwb_t *lwb) 1082 { 1083 zbookmark_phys_t zb; 1084 zio_priority_t prio; 1085 1086 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 1087 ASSERT3P(lwb, !=, NULL); 1088 EQUIV(lwb->lwb_root_zio == NULL, lwb->lwb_state == LWB_STATE_CLOSED); 1089 EQUIV(lwb->lwb_root_zio != NULL, lwb->lwb_state == LWB_STATE_OPENED); 1090 1091 SET_BOOKMARK(&zb, lwb->lwb_blk.blk_cksum.zc_word[ZIL_ZC_OBJSET], 1092 ZB_ZIL_OBJECT, ZB_ZIL_LEVEL, 1093 lwb->lwb_blk.blk_cksum.zc_word[ZIL_ZC_SEQ]); 1094 1095 if (lwb->lwb_root_zio == NULL) { 1096 abd_t *lwb_abd = abd_get_from_buf(lwb->lwb_buf, 1097 BP_GET_LSIZE(&lwb->lwb_blk)); 1098 1099 if (!lwb->lwb_slog || zilog->zl_cur_used <= zil_slog_bulk) 1100 prio = ZIO_PRIORITY_SYNC_WRITE; 1101 else 1102 prio = ZIO_PRIORITY_ASYNC_WRITE; 1103 1104 lwb->lwb_root_zio = zio_root(zilog->zl_spa, 1105 zil_lwb_flush_vdevs_done, lwb, ZIO_FLAG_CANFAIL); 1106 ASSERT3P(lwb->lwb_root_zio, !=, NULL); 1107 1108 lwb->lwb_write_zio = zio_rewrite(lwb->lwb_root_zio, 1109 zilog->zl_spa, 0, &lwb->lwb_blk, lwb_abd, 1110 BP_GET_LSIZE(&lwb->lwb_blk), zil_lwb_write_done, lwb, 1111 prio, ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_PROPAGATE, &zb); 1112 ASSERT3P(lwb->lwb_write_zio, !=, NULL); 1113 1114 lwb->lwb_state = LWB_STATE_OPENED; 1115 1116 mutex_enter(&zilog->zl_lock); 1117 1118 /* 1119 * The zilog's "zl_last_lwb_opened" field is used to 1120 * build the lwb/zio dependency chain, which is used to 1121 * preserve the ordering of lwb completions that is 1122 * required by the semantics of the ZIL. Each new lwb 1123 * zio becomes a parent of the "previous" lwb zio, such 1124 * that the new lwb's zio cannot complete until the 1125 * "previous" lwb's zio completes. 1126 * 1127 * This is required by the semantics of zil_commit(); 1128 * the commit waiters attached to the lwbs will be woken 1129 * in the lwb zio's completion callback, so this zio 1130 * dependency graph ensures the waiters are woken in the 1131 * correct order (the same order the lwbs were created). 1132 */ 1133 lwb_t *last_lwb_opened = zilog->zl_last_lwb_opened; 1134 if (last_lwb_opened != NULL && 1135 last_lwb_opened->lwb_state != LWB_STATE_DONE) { 1136 ASSERT(last_lwb_opened->lwb_state == LWB_STATE_OPENED || 1137 last_lwb_opened->lwb_state == LWB_STATE_ISSUED); 1138 ASSERT3P(last_lwb_opened->lwb_root_zio, !=, NULL); 1139 zio_add_child(lwb->lwb_root_zio, 1140 last_lwb_opened->lwb_root_zio); 1141 } 1142 zilog->zl_last_lwb_opened = lwb; 1143 1144 mutex_exit(&zilog->zl_lock); 1145 } 1146 1147 ASSERT3P(lwb->lwb_root_zio, !=, NULL); 1148 ASSERT3P(lwb->lwb_write_zio, !=, NULL); 1149 ASSERT3S(lwb->lwb_state, ==, LWB_STATE_OPENED); 1150 } 1151 1152 /* 1153 * Define a limited set of intent log block sizes. 1154 * 1155 * These must be a multiple of 4KB. Note only the amount used (again 1156 * aligned to 4KB) actually gets written. However, we can't always just 1157 * allocate SPA_OLD_MAXBLOCKSIZE as the slog space could be exhausted. 1158 */ 1159 uint64_t zil_block_buckets[] = { 1160 4096, /* non TX_WRITE */ 1161 8192+4096, /* data base */ 1162 32*1024 + 4096, /* NFS writes */ 1163 UINT64_MAX 1164 }; 1165 1166 /* 1167 * Start a log block write and advance to the next log block. 1168 * Calls are serialized. 1169 */ 1170 static lwb_t * 1171 zil_lwb_write_issue(zilog_t *zilog, lwb_t *lwb) 1172 { 1173 lwb_t *nlwb = NULL; 1174 zil_chain_t *zilc; 1175 spa_t *spa = zilog->zl_spa; 1176 blkptr_t *bp; 1177 dmu_tx_t *tx; 1178 uint64_t txg; 1179 uint64_t zil_blksz, wsz; 1180 int i, error; 1181 boolean_t slog; 1182 1183 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 1184 ASSERT3P(lwb->lwb_root_zio, !=, NULL); 1185 ASSERT3P(lwb->lwb_write_zio, !=, NULL); 1186 ASSERT3S(lwb->lwb_state, ==, LWB_STATE_OPENED); 1187 1188 if (BP_GET_CHECKSUM(&lwb->lwb_blk) == ZIO_CHECKSUM_ZILOG2) { 1189 zilc = (zil_chain_t *)lwb->lwb_buf; 1190 bp = &zilc->zc_next_blk; 1191 } else { 1192 zilc = (zil_chain_t *)(lwb->lwb_buf + lwb->lwb_sz); 1193 bp = &zilc->zc_next_blk; 1194 } 1195 1196 ASSERT(lwb->lwb_nused <= lwb->lwb_sz); 1197 1198 /* 1199 * Allocate the next block and save its address in this block 1200 * before writing it in order to establish the log chain. 1201 * Note that if the allocation of nlwb synced before we wrote 1202 * the block that points at it (lwb), we'd leak it if we crashed. 1203 * Therefore, we don't do dmu_tx_commit() until zil_lwb_write_done(). 1204 * We dirty the dataset to ensure that zil_sync() will be called 1205 * to clean up in the event of allocation failure or I/O failure. 1206 */ 1207 1208 tx = dmu_tx_create(zilog->zl_os); 1209 1210 /* 1211 * Since we are not going to create any new dirty data and we can even 1212 * help with clearing the existing dirty data, we should not be subject 1213 * to the dirty data based delays. 1214 * We (ab)use TXG_WAITED to bypass the delay mechanism. 1215 * One side effect from using TXG_WAITED is that dmu_tx_assign() can 1216 * fail if the pool is suspended. Those are dramatic circumstances, 1217 * so we return NULL to signal that the normal ZIL processing is not 1218 * possible and txg_wait_synced() should be used to ensure that the data 1219 * is on disk. 1220 */ 1221 error = dmu_tx_assign(tx, TXG_WAITED); 1222 if (error != 0) { 1223 ASSERT3S(error, ==, EIO); 1224 dmu_tx_abort(tx); 1225 return (NULL); 1226 } 1227 dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx); 1228 txg = dmu_tx_get_txg(tx); 1229 1230 lwb->lwb_tx = tx; 1231 1232 /* 1233 * Log blocks are pre-allocated. Here we select the size of the next 1234 * block, based on size used in the last block. 1235 * - first find the smallest bucket that will fit the block from a 1236 * limited set of block sizes. This is because it's faster to write 1237 * blocks allocated from the same metaslab as they are adjacent or 1238 * close. 1239 * - next find the maximum from the new suggested size and an array of 1240 * previous sizes. This lessens a picket fence effect of wrongly 1241 * guesssing the size if we have a stream of say 2k, 64k, 2k, 64k 1242 * requests. 1243 * 1244 * Note we only write what is used, but we can't just allocate 1245 * the maximum block size because we can exhaust the available 1246 * pool log space. 1247 */ 1248 zil_blksz = zilog->zl_cur_used + sizeof (zil_chain_t); 1249 for (i = 0; zil_blksz > zil_block_buckets[i]; i++) 1250 continue; 1251 zil_blksz = zil_block_buckets[i]; 1252 if (zil_blksz == UINT64_MAX) 1253 zil_blksz = SPA_OLD_MAXBLOCKSIZE; 1254 zilog->zl_prev_blks[zilog->zl_prev_rotor] = zil_blksz; 1255 for (i = 0; i < ZIL_PREV_BLKS; i++) 1256 zil_blksz = MAX(zil_blksz, zilog->zl_prev_blks[i]); 1257 zilog->zl_prev_rotor = (zilog->zl_prev_rotor + 1) & (ZIL_PREV_BLKS - 1); 1258 1259 BP_ZERO(bp); 1260 1261 /* pass the old blkptr in order to spread log blocks across devs */ 1262 error = zio_alloc_zil(spa, txg, bp, &lwb->lwb_blk, zil_blksz, &slog); 1263 if (error == 0) { 1264 ASSERT3U(bp->blk_birth, ==, txg); 1265 bp->blk_cksum = lwb->lwb_blk.blk_cksum; 1266 bp->blk_cksum.zc_word[ZIL_ZC_SEQ]++; 1267 1268 /* 1269 * Allocate a new log write block (lwb). 1270 */ 1271 nlwb = zil_alloc_lwb(zilog, bp, slog, txg); 1272 } 1273 1274 if (BP_GET_CHECKSUM(&lwb->lwb_blk) == ZIO_CHECKSUM_ZILOG2) { 1275 /* For Slim ZIL only write what is used. */ 1276 wsz = P2ROUNDUP_TYPED(lwb->lwb_nused, ZIL_MIN_BLKSZ, uint64_t); 1277 ASSERT3U(wsz, <=, lwb->lwb_sz); 1278 zio_shrink(lwb->lwb_write_zio, wsz); 1279 1280 } else { 1281 wsz = lwb->lwb_sz; 1282 } 1283 1284 zilc->zc_pad = 0; 1285 zilc->zc_nused = lwb->lwb_nused; 1286 zilc->zc_eck.zec_cksum = lwb->lwb_blk.blk_cksum; 1287 1288 /* 1289 * clear unused data for security 1290 */ 1291 bzero(lwb->lwb_buf + lwb->lwb_nused, wsz - lwb->lwb_nused); 1292 1293 spa_config_enter(zilog->zl_spa, SCL_STATE, lwb, RW_READER); 1294 1295 zil_lwb_add_block(lwb, &lwb->lwb_blk); 1296 lwb->lwb_issued_timestamp = gethrtime(); 1297 lwb->lwb_state = LWB_STATE_ISSUED; 1298 1299 zio_nowait(lwb->lwb_root_zio); 1300 zio_nowait(lwb->lwb_write_zio); 1301 1302 /* 1303 * If there was an allocation failure then nlwb will be null which 1304 * forces a txg_wait_synced(). 1305 */ 1306 return (nlwb); 1307 } 1308 1309 static lwb_t * 1310 zil_lwb_commit(zilog_t *zilog, itx_t *itx, lwb_t *lwb) 1311 { 1312 lr_t *lrcb, *lrc; 1313 lr_write_t *lrwb, *lrw; 1314 char *lr_buf; 1315 uint64_t dlen, dnow, lwb_sp, reclen, txg; 1316 1317 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 1318 ASSERT3P(lwb, !=, NULL); 1319 ASSERT3P(lwb->lwb_buf, !=, NULL); 1320 1321 zil_lwb_write_open(zilog, lwb); 1322 1323 lrc = &itx->itx_lr; 1324 lrw = (lr_write_t *)lrc; 1325 1326 /* 1327 * A commit itx doesn't represent any on-disk state; instead 1328 * it's simply used as a place holder on the commit list, and 1329 * provides a mechanism for attaching a "commit waiter" onto the 1330 * correct lwb (such that the waiter can be signalled upon 1331 * completion of that lwb). Thus, we don't process this itx's 1332 * log record if it's a commit itx (these itx's don't have log 1333 * records), and instead link the itx's waiter onto the lwb's 1334 * list of waiters. 1335 * 1336 * For more details, see the comment above zil_commit(). 1337 */ 1338 if (lrc->lrc_txtype == TX_COMMIT) { 1339 mutex_enter(&zilog->zl_lock); 1340 zil_commit_waiter_link_lwb(itx->itx_private, lwb); 1341 itx->itx_private = NULL; 1342 mutex_exit(&zilog->zl_lock); 1343 return (lwb); 1344 } 1345 1346 if (lrc->lrc_txtype == TX_WRITE && itx->itx_wr_state == WR_NEED_COPY) { 1347 dlen = P2ROUNDUP_TYPED( 1348 lrw->lr_length, sizeof (uint64_t), uint64_t); 1349 } else { 1350 dlen = 0; 1351 } 1352 reclen = lrc->lrc_reclen; 1353 zilog->zl_cur_used += (reclen + dlen); 1354 txg = lrc->lrc_txg; 1355 1356 ASSERT3U(zilog->zl_cur_used, <, UINT64_MAX - (reclen + dlen)); 1357 1358 cont: 1359 /* 1360 * If this record won't fit in the current log block, start a new one. 1361 * For WR_NEED_COPY optimize layout for minimal number of chunks. 1362 */ 1363 lwb_sp = lwb->lwb_sz - lwb->lwb_nused; 1364 if (reclen > lwb_sp || (reclen + dlen > lwb_sp && 1365 lwb_sp < ZIL_MAX_WASTE_SPACE && (dlen % ZIL_MAX_LOG_DATA == 0 || 1366 lwb_sp < reclen + dlen % ZIL_MAX_LOG_DATA))) { 1367 lwb = zil_lwb_write_issue(zilog, lwb); 1368 if (lwb == NULL) 1369 return (NULL); 1370 zil_lwb_write_open(zilog, lwb); 1371 ASSERT(LWB_EMPTY(lwb)); 1372 lwb_sp = lwb->lwb_sz - lwb->lwb_nused; 1373 ASSERT3U(reclen + MIN(dlen, sizeof (uint64_t)), <=, lwb_sp); 1374 } 1375 1376 dnow = MIN(dlen, lwb_sp - reclen); 1377 lr_buf = lwb->lwb_buf + lwb->lwb_nused; 1378 bcopy(lrc, lr_buf, reclen); 1379 lrcb = (lr_t *)lr_buf; /* Like lrc, but inside lwb. */ 1380 lrwb = (lr_write_t *)lrcb; /* Like lrw, but inside lwb. */ 1381 1382 /* 1383 * If it's a write, fetch the data or get its blkptr as appropriate. 1384 */ 1385 if (lrc->lrc_txtype == TX_WRITE) { 1386 if (txg > spa_freeze_txg(zilog->zl_spa)) 1387 txg_wait_synced(zilog->zl_dmu_pool, txg); 1388 if (itx->itx_wr_state != WR_COPIED) { 1389 char *dbuf; 1390 int error; 1391 1392 if (itx->itx_wr_state == WR_NEED_COPY) { 1393 dbuf = lr_buf + reclen; 1394 lrcb->lrc_reclen += dnow; 1395 if (lrwb->lr_length > dnow) 1396 lrwb->lr_length = dnow; 1397 lrw->lr_offset += dnow; 1398 lrw->lr_length -= dnow; 1399 } else { 1400 ASSERT(itx->itx_wr_state == WR_INDIRECT); 1401 dbuf = NULL; 1402 } 1403 1404 /* 1405 * We pass in the "lwb_write_zio" rather than 1406 * "lwb_root_zio" so that the "lwb_write_zio" 1407 * becomes the parent of any zio's created by 1408 * the "zl_get_data" callback. The vdevs are 1409 * flushed after the "lwb_write_zio" completes, 1410 * so we want to make sure that completion 1411 * callback waits for these additional zio's, 1412 * such that the vdevs used by those zio's will 1413 * be included in the lwb's vdev tree, and those 1414 * vdevs will be properly flushed. If we passed 1415 * in "lwb_root_zio" here, then these additional 1416 * vdevs may not be flushed; e.g. if these zio's 1417 * completed after "lwb_write_zio" completed. 1418 */ 1419 error = zilog->zl_get_data(itx->itx_private, 1420 lrwb, dbuf, lwb, lwb->lwb_write_zio); 1421 1422 if (error == EIO) { 1423 txg_wait_synced(zilog->zl_dmu_pool, txg); 1424 return (lwb); 1425 } 1426 if (error != 0) { 1427 ASSERT(error == ENOENT || error == EEXIST || 1428 error == EALREADY); 1429 return (lwb); 1430 } 1431 } 1432 } 1433 1434 /* 1435 * We're actually making an entry, so update lrc_seq to be the 1436 * log record sequence number. Note that this is generally not 1437 * equal to the itx sequence number because not all transactions 1438 * are synchronous, and sometimes spa_sync() gets there first. 1439 */ 1440 lrcb->lrc_seq = ++zilog->zl_lr_seq; 1441 lwb->lwb_nused += reclen + dnow; 1442 1443 zil_lwb_add_txg(lwb, txg); 1444 1445 ASSERT3U(lwb->lwb_nused, <=, lwb->lwb_sz); 1446 ASSERT0(P2PHASE(lwb->lwb_nused, sizeof (uint64_t))); 1447 1448 dlen -= dnow; 1449 if (dlen > 0) { 1450 zilog->zl_cur_used += reclen; 1451 goto cont; 1452 } 1453 1454 return (lwb); 1455 } 1456 1457 itx_t * 1458 zil_itx_create(uint64_t txtype, size_t lrsize) 1459 { 1460 itx_t *itx; 1461 1462 lrsize = P2ROUNDUP_TYPED(lrsize, sizeof (uint64_t), size_t); 1463 1464 itx = kmem_alloc(offsetof(itx_t, itx_lr) + lrsize, KM_SLEEP); 1465 itx->itx_lr.lrc_txtype = txtype; 1466 itx->itx_lr.lrc_reclen = lrsize; 1467 itx->itx_lr.lrc_seq = 0; /* defensive */ 1468 itx->itx_sync = B_TRUE; /* default is synchronous */ 1469 1470 return (itx); 1471 } 1472 1473 void 1474 zil_itx_destroy(itx_t *itx) 1475 { 1476 kmem_free(itx, offsetof(itx_t, itx_lr) + itx->itx_lr.lrc_reclen); 1477 } 1478 1479 /* 1480 * Free up the sync and async itxs. The itxs_t has already been detached 1481 * so no locks are needed. 1482 */ 1483 static void 1484 zil_itxg_clean(itxs_t *itxs) 1485 { 1486 itx_t *itx; 1487 list_t *list; 1488 avl_tree_t *t; 1489 void *cookie; 1490 itx_async_node_t *ian; 1491 1492 list = &itxs->i_sync_list; 1493 while ((itx = list_head(list)) != NULL) { 1494 /* 1495 * In the general case, commit itxs will not be found 1496 * here, as they'll be committed to an lwb via 1497 * zil_lwb_commit(), and free'd in that function. Having 1498 * said that, it is still possible for commit itxs to be 1499 * found here, due to the following race: 1500 * 1501 * - a thread calls zil_commit() which assigns the 1502 * commit itx to a per-txg i_sync_list 1503 * - zil_itxg_clean() is called (e.g. via spa_sync()) 1504 * while the waiter is still on the i_sync_list 1505 * 1506 * There's nothing to prevent syncing the txg while the 1507 * waiter is on the i_sync_list. This normally doesn't 1508 * happen because spa_sync() is slower than zil_commit(), 1509 * but if zil_commit() calls txg_wait_synced() (e.g. 1510 * because zil_create() or zil_commit_writer_stall() is 1511 * called) we will hit this case. 1512 */ 1513 if (itx->itx_lr.lrc_txtype == TX_COMMIT) 1514 zil_commit_waiter_skip(itx->itx_private); 1515 1516 list_remove(list, itx); 1517 zil_itx_destroy(itx); 1518 } 1519 1520 cookie = NULL; 1521 t = &itxs->i_async_tree; 1522 while ((ian = avl_destroy_nodes(t, &cookie)) != NULL) { 1523 list = &ian->ia_list; 1524 while ((itx = list_head(list)) != NULL) { 1525 list_remove(list, itx); 1526 /* commit itxs should never be on the async lists. */ 1527 ASSERT3U(itx->itx_lr.lrc_txtype, !=, TX_COMMIT); 1528 zil_itx_destroy(itx); 1529 } 1530 list_destroy(list); 1531 kmem_free(ian, sizeof (itx_async_node_t)); 1532 } 1533 avl_destroy(t); 1534 1535 kmem_free(itxs, sizeof (itxs_t)); 1536 } 1537 1538 static int 1539 zil_aitx_compare(const void *x1, const void *x2) 1540 { 1541 const uint64_t o1 = ((itx_async_node_t *)x1)->ia_foid; 1542 const uint64_t o2 = ((itx_async_node_t *)x2)->ia_foid; 1543 1544 if (o1 < o2) 1545 return (-1); 1546 if (o1 > o2) 1547 return (1); 1548 1549 return (0); 1550 } 1551 1552 /* 1553 * Remove all async itx with the given oid. 1554 */ 1555 static void 1556 zil_remove_async(zilog_t *zilog, uint64_t oid) 1557 { 1558 uint64_t otxg, txg; 1559 itx_async_node_t *ian; 1560 avl_tree_t *t; 1561 avl_index_t where; 1562 list_t clean_list; 1563 itx_t *itx; 1564 1565 ASSERT(oid != 0); 1566 list_create(&clean_list, sizeof (itx_t), offsetof(itx_t, itx_node)); 1567 1568 if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) /* ziltest support */ 1569 otxg = ZILTEST_TXG; 1570 else 1571 otxg = spa_last_synced_txg(zilog->zl_spa) + 1; 1572 1573 for (txg = otxg; txg < (otxg + TXG_CONCURRENT_STATES); txg++) { 1574 itxg_t *itxg = &zilog->zl_itxg[txg & TXG_MASK]; 1575 1576 mutex_enter(&itxg->itxg_lock); 1577 if (itxg->itxg_txg != txg) { 1578 mutex_exit(&itxg->itxg_lock); 1579 continue; 1580 } 1581 1582 /* 1583 * Locate the object node and append its list. 1584 */ 1585 t = &itxg->itxg_itxs->i_async_tree; 1586 ian = avl_find(t, &oid, &where); 1587 if (ian != NULL) 1588 list_move_tail(&clean_list, &ian->ia_list); 1589 mutex_exit(&itxg->itxg_lock); 1590 } 1591 while ((itx = list_head(&clean_list)) != NULL) { 1592 list_remove(&clean_list, itx); 1593 /* commit itxs should never be on the async lists. */ 1594 ASSERT3U(itx->itx_lr.lrc_txtype, !=, TX_COMMIT); 1595 zil_itx_destroy(itx); 1596 } 1597 list_destroy(&clean_list); 1598 } 1599 1600 void 1601 zil_itx_assign(zilog_t *zilog, itx_t *itx, dmu_tx_t *tx) 1602 { 1603 uint64_t txg; 1604 itxg_t *itxg; 1605 itxs_t *itxs, *clean = NULL; 1606 1607 /* 1608 * Object ids can be re-instantiated in the next txg so 1609 * remove any async transactions to avoid future leaks. 1610 * This can happen if a fsync occurs on the re-instantiated 1611 * object for a WR_INDIRECT or WR_NEED_COPY write, which gets 1612 * the new file data and flushes a write record for the old object. 1613 */ 1614 if ((itx->itx_lr.lrc_txtype & ~TX_CI) == TX_REMOVE) 1615 zil_remove_async(zilog, itx->itx_oid); 1616 1617 /* 1618 * Ensure the data of a renamed file is committed before the rename. 1619 */ 1620 if ((itx->itx_lr.lrc_txtype & ~TX_CI) == TX_RENAME) 1621 zil_async_to_sync(zilog, itx->itx_oid); 1622 1623 if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) 1624 txg = ZILTEST_TXG; 1625 else 1626 txg = dmu_tx_get_txg(tx); 1627 1628 itxg = &zilog->zl_itxg[txg & TXG_MASK]; 1629 mutex_enter(&itxg->itxg_lock); 1630 itxs = itxg->itxg_itxs; 1631 if (itxg->itxg_txg != txg) { 1632 if (itxs != NULL) { 1633 /* 1634 * The zil_clean callback hasn't got around to cleaning 1635 * this itxg. Save the itxs for release below. 1636 * This should be rare. 1637 */ 1638 zfs_dbgmsg("zil_itx_assign: missed itx cleanup for " 1639 "txg %llu", itxg->itxg_txg); 1640 clean = itxg->itxg_itxs; 1641 } 1642 itxg->itxg_txg = txg; 1643 itxs = itxg->itxg_itxs = kmem_zalloc(sizeof (itxs_t), KM_SLEEP); 1644 1645 list_create(&itxs->i_sync_list, sizeof (itx_t), 1646 offsetof(itx_t, itx_node)); 1647 avl_create(&itxs->i_async_tree, zil_aitx_compare, 1648 sizeof (itx_async_node_t), 1649 offsetof(itx_async_node_t, ia_node)); 1650 } 1651 if (itx->itx_sync) { 1652 list_insert_tail(&itxs->i_sync_list, itx); 1653 } else { 1654 avl_tree_t *t = &itxs->i_async_tree; 1655 uint64_t foid = ((lr_ooo_t *)&itx->itx_lr)->lr_foid; 1656 itx_async_node_t *ian; 1657 avl_index_t where; 1658 1659 ian = avl_find(t, &foid, &where); 1660 if (ian == NULL) { 1661 ian = kmem_alloc(sizeof (itx_async_node_t), KM_SLEEP); 1662 list_create(&ian->ia_list, sizeof (itx_t), 1663 offsetof(itx_t, itx_node)); 1664 ian->ia_foid = foid; 1665 avl_insert(t, ian, where); 1666 } 1667 list_insert_tail(&ian->ia_list, itx); 1668 } 1669 1670 itx->itx_lr.lrc_txg = dmu_tx_get_txg(tx); 1671 1672 /* 1673 * We don't want to dirty the ZIL using ZILTEST_TXG, because 1674 * zil_clean() will never be called using ZILTEST_TXG. Thus, we 1675 * need to be careful to always dirty the ZIL using the "real" 1676 * TXG (not itxg_txg) even when the SPA is frozen. 1677 */ 1678 zilog_dirty(zilog, dmu_tx_get_txg(tx)); 1679 mutex_exit(&itxg->itxg_lock); 1680 1681 /* Release the old itxs now we've dropped the lock */ 1682 if (clean != NULL) 1683 zil_itxg_clean(clean); 1684 } 1685 1686 /* 1687 * If there are any in-memory intent log transactions which have now been 1688 * synced then start up a taskq to free them. We should only do this after we 1689 * have written out the uberblocks (i.e. txg has been comitted) so that 1690 * don't inadvertently clean out in-memory log records that would be required 1691 * by zil_commit(). 1692 */ 1693 void 1694 zil_clean(zilog_t *zilog, uint64_t synced_txg) 1695 { 1696 itxg_t *itxg = &zilog->zl_itxg[synced_txg & TXG_MASK]; 1697 itxs_t *clean_me; 1698 1699 ASSERT3U(synced_txg, <, ZILTEST_TXG); 1700 1701 mutex_enter(&itxg->itxg_lock); 1702 if (itxg->itxg_itxs == NULL || itxg->itxg_txg == ZILTEST_TXG) { 1703 mutex_exit(&itxg->itxg_lock); 1704 return; 1705 } 1706 ASSERT3U(itxg->itxg_txg, <=, synced_txg); 1707 ASSERT3U(itxg->itxg_txg, !=, 0); 1708 clean_me = itxg->itxg_itxs; 1709 itxg->itxg_itxs = NULL; 1710 itxg->itxg_txg = 0; 1711 mutex_exit(&itxg->itxg_lock); 1712 /* 1713 * Preferably start a task queue to free up the old itxs but 1714 * if taskq_dispatch can't allocate resources to do that then 1715 * free it in-line. This should be rare. Note, using TQ_SLEEP 1716 * created a bad performance problem. 1717 */ 1718 ASSERT3P(zilog->zl_dmu_pool, !=, NULL); 1719 ASSERT3P(zilog->zl_dmu_pool->dp_zil_clean_taskq, !=, NULL); 1720 if (taskq_dispatch(zilog->zl_dmu_pool->dp_zil_clean_taskq, 1721 (void (*)(void *))zil_itxg_clean, clean_me, TQ_NOSLEEP) == NULL) 1722 zil_itxg_clean(clean_me); 1723 } 1724 1725 /* 1726 * This function will traverse the queue of itxs that need to be 1727 * committed, and move them onto the ZIL's zl_itx_commit_list. 1728 */ 1729 static void 1730 zil_get_commit_list(zilog_t *zilog) 1731 { 1732 uint64_t otxg, txg; 1733 list_t *commit_list = &zilog->zl_itx_commit_list; 1734 1735 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 1736 1737 if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) /* ziltest support */ 1738 otxg = ZILTEST_TXG; 1739 else 1740 otxg = spa_last_synced_txg(zilog->zl_spa) + 1; 1741 1742 /* 1743 * This is inherently racy, since there is nothing to prevent 1744 * the last synced txg from changing. That's okay since we'll 1745 * only commit things in the future. 1746 */ 1747 for (txg = otxg; txg < (otxg + TXG_CONCURRENT_STATES); txg++) { 1748 itxg_t *itxg = &zilog->zl_itxg[txg & TXG_MASK]; 1749 1750 mutex_enter(&itxg->itxg_lock); 1751 if (itxg->itxg_txg != txg) { 1752 mutex_exit(&itxg->itxg_lock); 1753 continue; 1754 } 1755 1756 /* 1757 * If we're adding itx records to the zl_itx_commit_list, 1758 * then the zil better be dirty in this "txg". We can assert 1759 * that here since we're holding the itxg_lock which will 1760 * prevent spa_sync from cleaning it. Once we add the itxs 1761 * to the zl_itx_commit_list we must commit it to disk even 1762 * if it's unnecessary (i.e. the txg was synced). 1763 */ 1764 ASSERT(zilog_is_dirty_in_txg(zilog, txg) || 1765 spa_freeze_txg(zilog->zl_spa) != UINT64_MAX); 1766 list_move_tail(commit_list, &itxg->itxg_itxs->i_sync_list); 1767 1768 mutex_exit(&itxg->itxg_lock); 1769 } 1770 } 1771 1772 /* 1773 * Move the async itxs for a specified object to commit into sync lists. 1774 */ 1775 static void 1776 zil_async_to_sync(zilog_t *zilog, uint64_t foid) 1777 { 1778 uint64_t otxg, txg; 1779 itx_async_node_t *ian; 1780 avl_tree_t *t; 1781 avl_index_t where; 1782 1783 if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) /* ziltest support */ 1784 otxg = ZILTEST_TXG; 1785 else 1786 otxg = spa_last_synced_txg(zilog->zl_spa) + 1; 1787 1788 /* 1789 * This is inherently racy, since there is nothing to prevent 1790 * the last synced txg from changing. 1791 */ 1792 for (txg = otxg; txg < (otxg + TXG_CONCURRENT_STATES); txg++) { 1793 itxg_t *itxg = &zilog->zl_itxg[txg & TXG_MASK]; 1794 1795 mutex_enter(&itxg->itxg_lock); 1796 if (itxg->itxg_txg != txg) { 1797 mutex_exit(&itxg->itxg_lock); 1798 continue; 1799 } 1800 1801 /* 1802 * If a foid is specified then find that node and append its 1803 * list. Otherwise walk the tree appending all the lists 1804 * to the sync list. We add to the end rather than the 1805 * beginning to ensure the create has happened. 1806 */ 1807 t = &itxg->itxg_itxs->i_async_tree; 1808 if (foid != 0) { 1809 ian = avl_find(t, &foid, &where); 1810 if (ian != NULL) { 1811 list_move_tail(&itxg->itxg_itxs->i_sync_list, 1812 &ian->ia_list); 1813 } 1814 } else { 1815 void *cookie = NULL; 1816 1817 while ((ian = avl_destroy_nodes(t, &cookie)) != NULL) { 1818 list_move_tail(&itxg->itxg_itxs->i_sync_list, 1819 &ian->ia_list); 1820 list_destroy(&ian->ia_list); 1821 kmem_free(ian, sizeof (itx_async_node_t)); 1822 } 1823 } 1824 mutex_exit(&itxg->itxg_lock); 1825 } 1826 } 1827 1828 /* 1829 * This function will prune commit itxs that are at the head of the 1830 * commit list (it won't prune past the first non-commit itx), and 1831 * either: a) attach them to the last lwb that's still pending 1832 * completion, or b) skip them altogether. 1833 * 1834 * This is used as a performance optimization to prevent commit itxs 1835 * from generating new lwbs when it's unnecessary to do so. 1836 */ 1837 static void 1838 zil_prune_commit_list(zilog_t *zilog) 1839 { 1840 itx_t *itx; 1841 1842 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 1843 1844 while (itx = list_head(&zilog->zl_itx_commit_list)) { 1845 lr_t *lrc = &itx->itx_lr; 1846 if (lrc->lrc_txtype != TX_COMMIT) 1847 break; 1848 1849 mutex_enter(&zilog->zl_lock); 1850 1851 lwb_t *last_lwb = zilog->zl_last_lwb_opened; 1852 if (last_lwb == NULL || last_lwb->lwb_state == LWB_STATE_DONE) { 1853 /* 1854 * All of the itxs this waiter was waiting on 1855 * must have already completed (or there were 1856 * never any itx's for it to wait on), so it's 1857 * safe to skip this waiter and mark it done. 1858 */ 1859 zil_commit_waiter_skip(itx->itx_private); 1860 } else { 1861 zil_commit_waiter_link_lwb(itx->itx_private, last_lwb); 1862 itx->itx_private = NULL; 1863 } 1864 1865 mutex_exit(&zilog->zl_lock); 1866 1867 list_remove(&zilog->zl_itx_commit_list, itx); 1868 zil_itx_destroy(itx); 1869 } 1870 1871 IMPLY(itx != NULL, itx->itx_lr.lrc_txtype != TX_COMMIT); 1872 } 1873 1874 static void 1875 zil_commit_writer_stall(zilog_t *zilog) 1876 { 1877 /* 1878 * When zio_alloc_zil() fails to allocate the next lwb block on 1879 * disk, we must call txg_wait_synced() to ensure all of the 1880 * lwbs in the zilog's zl_lwb_list are synced and then freed (in 1881 * zil_sync()), such that any subsequent ZIL writer (i.e. a call 1882 * to zil_process_commit_list()) will have to call zil_create(), 1883 * and start a new ZIL chain. 1884 * 1885 * Since zil_alloc_zil() failed, the lwb that was previously 1886 * issued does not have a pointer to the "next" lwb on disk. 1887 * Thus, if another ZIL writer thread was to allocate the "next" 1888 * on-disk lwb, that block could be leaked in the event of a 1889 * crash (because the previous lwb on-disk would not point to 1890 * it). 1891 * 1892 * We must hold the zilog's zl_issuer_lock while we do this, to 1893 * ensure no new threads enter zil_process_commit_list() until 1894 * all lwb's in the zl_lwb_list have been synced and freed 1895 * (which is achieved via the txg_wait_synced() call). 1896 */ 1897 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 1898 txg_wait_synced(zilog->zl_dmu_pool, 0); 1899 ASSERT3P(list_tail(&zilog->zl_lwb_list), ==, NULL); 1900 } 1901 1902 /* 1903 * This function will traverse the commit list, creating new lwbs as 1904 * needed, and committing the itxs from the commit list to these newly 1905 * created lwbs. Additionally, as a new lwb is created, the previous 1906 * lwb will be issued to the zio layer to be written to disk. 1907 */ 1908 static void 1909 zil_process_commit_list(zilog_t *zilog) 1910 { 1911 spa_t *spa = zilog->zl_spa; 1912 list_t nolwb_waiters; 1913 lwb_t *lwb; 1914 itx_t *itx; 1915 1916 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 1917 1918 /* 1919 * Return if there's nothing to commit before we dirty the fs by 1920 * calling zil_create(). 1921 */ 1922 if (list_head(&zilog->zl_itx_commit_list) == NULL) 1923 return; 1924 1925 list_create(&nolwb_waiters, sizeof (zil_commit_waiter_t), 1926 offsetof(zil_commit_waiter_t, zcw_node)); 1927 1928 lwb = list_tail(&zilog->zl_lwb_list); 1929 if (lwb == NULL) { 1930 lwb = zil_create(zilog); 1931 } else { 1932 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_ISSUED); 1933 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_DONE); 1934 } 1935 1936 while (itx = list_head(&zilog->zl_itx_commit_list)) { 1937 lr_t *lrc = &itx->itx_lr; 1938 uint64_t txg = lrc->lrc_txg; 1939 1940 ASSERT3U(txg, !=, 0); 1941 1942 if (lrc->lrc_txtype == TX_COMMIT) { 1943 DTRACE_PROBE2(zil__process__commit__itx, 1944 zilog_t *, zilog, itx_t *, itx); 1945 } else { 1946 DTRACE_PROBE2(zil__process__normal__itx, 1947 zilog_t *, zilog, itx_t *, itx); 1948 } 1949 1950 boolean_t synced = txg <= spa_last_synced_txg(spa); 1951 boolean_t frozen = txg > spa_freeze_txg(spa); 1952 1953 /* 1954 * If the txg of this itx has already been synced out, then 1955 * we don't need to commit this itx to an lwb. This is 1956 * because the data of this itx will have already been 1957 * written to the main pool. This is inherently racy, and 1958 * it's still ok to commit an itx whose txg has already 1959 * been synced; this will result in a write that's 1960 * unnecessary, but will do no harm. 1961 * 1962 * With that said, we always want to commit TX_COMMIT itxs 1963 * to an lwb, regardless of whether or not that itx's txg 1964 * has been synced out. We do this to ensure any OPENED lwb 1965 * will always have at least one zil_commit_waiter_t linked 1966 * to the lwb. 1967 * 1968 * As a counter-example, if we skipped TX_COMMIT itx's 1969 * whose txg had already been synced, the following 1970 * situation could occur if we happened to be racing with 1971 * spa_sync: 1972 * 1973 * 1. we commit a non-TX_COMMIT itx to an lwb, where the 1974 * itx's txg is 10 and the last synced txg is 9. 1975 * 2. spa_sync finishes syncing out txg 10. 1976 * 3. we move to the next itx in the list, it's a TX_COMMIT 1977 * whose txg is 10, so we skip it rather than committing 1978 * it to the lwb used in (1). 1979 * 1980 * If the itx that is skipped in (3) is the last TX_COMMIT 1981 * itx in the commit list, than it's possible for the lwb 1982 * used in (1) to remain in the OPENED state indefinitely. 1983 * 1984 * To prevent the above scenario from occuring, ensuring 1985 * that once an lwb is OPENED it will transition to ISSUED 1986 * and eventually DONE, we always commit TX_COMMIT itx's to 1987 * an lwb here, even if that itx's txg has already been 1988 * synced. 1989 * 1990 * Finally, if the pool is frozen, we _always_ commit the 1991 * itx. The point of freezing the pool is to prevent data 1992 * from being written to the main pool via spa_sync, and 1993 * instead rely solely on the ZIL to persistently store the 1994 * data; i.e. when the pool is frozen, the last synced txg 1995 * value can't be trusted. 1996 */ 1997 if (frozen || !synced || lrc->lrc_txtype == TX_COMMIT) { 1998 if (lwb != NULL) { 1999 lwb = zil_lwb_commit(zilog, itx, lwb); 2000 } else if (lrc->lrc_txtype == TX_COMMIT) { 2001 ASSERT3P(lwb, ==, NULL); 2002 zil_commit_waiter_link_nolwb( 2003 itx->itx_private, &nolwb_waiters); 2004 } 2005 } 2006 2007 list_remove(&zilog->zl_itx_commit_list, itx); 2008 zil_itx_destroy(itx); 2009 } 2010 2011 if (lwb == NULL) { 2012 /* 2013 * This indicates zio_alloc_zil() failed to allocate the 2014 * "next" lwb on-disk. When this happens, we must stall 2015 * the ZIL write pipeline; see the comment within 2016 * zil_commit_writer_stall() for more details. 2017 */ 2018 zil_commit_writer_stall(zilog); 2019 2020 /* 2021 * Additionally, we have to signal and mark the "nolwb" 2022 * waiters as "done" here, since without an lwb, we 2023 * can't do this via zil_lwb_flush_vdevs_done() like 2024 * normal. 2025 */ 2026 zil_commit_waiter_t *zcw; 2027 while (zcw = list_head(&nolwb_waiters)) { 2028 zil_commit_waiter_skip(zcw); 2029 list_remove(&nolwb_waiters, zcw); 2030 } 2031 } else { 2032 ASSERT(list_is_empty(&nolwb_waiters)); 2033 ASSERT3P(lwb, !=, NULL); 2034 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_ISSUED); 2035 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_DONE); 2036 2037 /* 2038 * At this point, the ZIL block pointed at by the "lwb" 2039 * variable is in one of the following states: "closed" 2040 * or "open". 2041 * 2042 * If its "closed", then no itxs have been committed to 2043 * it, so there's no point in issuing its zio (i.e. 2044 * it's "empty"). 2045 * 2046 * If its "open" state, then it contains one or more 2047 * itxs that eventually need to be committed to stable 2048 * storage. In this case we intentionally do not issue 2049 * the lwb's zio to disk yet, and instead rely on one of 2050 * the following two mechanisms for issuing the zio: 2051 * 2052 * 1. Ideally, there will be more ZIL activity occuring 2053 * on the system, such that this function will be 2054 * immediately called again (not necessarily by the same 2055 * thread) and this lwb's zio will be issued via 2056 * zil_lwb_commit(). This way, the lwb is guaranteed to 2057 * be "full" when it is issued to disk, and we'll make 2058 * use of the lwb's size the best we can. 2059 * 2060 * 2. If there isn't sufficient ZIL activity occuring on 2061 * the system, such that this lwb's zio isn't issued via 2062 * zil_lwb_commit(), zil_commit_waiter() will issue the 2063 * lwb's zio. If this occurs, the lwb is not guaranteed 2064 * to be "full" by the time its zio is issued, and means 2065 * the size of the lwb was "too large" given the amount 2066 * of ZIL activity occuring on the system at that time. 2067 * 2068 * We do this for a couple of reasons: 2069 * 2070 * 1. To try and reduce the number of IOPs needed to 2071 * write the same number of itxs. If an lwb has space 2072 * available in it's buffer for more itxs, and more itxs 2073 * will be committed relatively soon (relative to the 2074 * latency of performing a write), then it's beneficial 2075 * to wait for these "next" itxs. This way, more itxs 2076 * can be committed to stable storage with fewer writes. 2077 * 2078 * 2. To try and use the largest lwb block size that the 2079 * incoming rate of itxs can support. Again, this is to 2080 * try and pack as many itxs into as few lwbs as 2081 * possible, without significantly impacting the latency 2082 * of each individual itx. 2083 */ 2084 } 2085 } 2086 2087 /* 2088 * This function is responsible for ensuring the passed in commit waiter 2089 * (and associated commit itx) is committed to an lwb. If the waiter is 2090 * not already committed to an lwb, all itxs in the zilog's queue of 2091 * itxs will be processed. The assumption is the passed in waiter's 2092 * commit itx will found in the queue just like the other non-commit 2093 * itxs, such that when the entire queue is processed, the waiter will 2094 * have been commited to an lwb. 2095 * 2096 * The lwb associated with the passed in waiter is not guaranteed to 2097 * have been issued by the time this function completes. If the lwb is 2098 * not issued, we rely on future calls to zil_commit_writer() to issue 2099 * the lwb, or the timeout mechanism found in zil_commit_waiter(). 2100 */ 2101 static void 2102 zil_commit_writer(zilog_t *zilog, zil_commit_waiter_t *zcw) 2103 { 2104 ASSERT(!MUTEX_HELD(&zilog->zl_lock)); 2105 ASSERT(spa_writeable(zilog->zl_spa)); 2106 2107 mutex_enter(&zilog->zl_issuer_lock); 2108 2109 if (zcw->zcw_lwb != NULL || zcw->zcw_done) { 2110 /* 2111 * It's possible that, while we were waiting to acquire 2112 * the "zl_issuer_lock", another thread committed this 2113 * waiter to an lwb. If that occurs, we bail out early, 2114 * without processing any of the zilog's queue of itxs. 2115 * 2116 * On certain workloads and system configurations, the 2117 * "zl_issuer_lock" can become highly contended. In an 2118 * attempt to reduce this contention, we immediately drop 2119 * the lock if the waiter has already been processed. 2120 * 2121 * We've measured this optimization to reduce CPU spent 2122 * contending on this lock by up to 5%, using a system 2123 * with 32 CPUs, low latency storage (~50 usec writes), 2124 * and 1024 threads performing sync writes. 2125 */ 2126 goto out; 2127 } 2128 2129 zil_get_commit_list(zilog); 2130 zil_prune_commit_list(zilog); 2131 zil_process_commit_list(zilog); 2132 2133 out: 2134 mutex_exit(&zilog->zl_issuer_lock); 2135 } 2136 2137 static void 2138 zil_commit_waiter_timeout(zilog_t *zilog, zil_commit_waiter_t *zcw) 2139 { 2140 ASSERT(!MUTEX_HELD(&zilog->zl_issuer_lock)); 2141 ASSERT(MUTEX_HELD(&zcw->zcw_lock)); 2142 ASSERT3B(zcw->zcw_done, ==, B_FALSE); 2143 2144 lwb_t *lwb = zcw->zcw_lwb; 2145 ASSERT3P(lwb, !=, NULL); 2146 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_CLOSED); 2147 2148 /* 2149 * If the lwb has already been issued by another thread, we can 2150 * immediately return since there's no work to be done (the 2151 * point of this function is to issue the lwb). Additionally, we 2152 * do this prior to acquiring the zl_issuer_lock, to avoid 2153 * acquiring it when it's not necessary to do so. 2154 */ 2155 if (lwb->lwb_state == LWB_STATE_ISSUED || 2156 lwb->lwb_state == LWB_STATE_DONE) 2157 return; 2158 2159 /* 2160 * In order to call zil_lwb_write_issue() we must hold the 2161 * zilog's "zl_issuer_lock". We can't simply acquire that lock, 2162 * since we're already holding the commit waiter's "zcw_lock", 2163 * and those two locks are aquired in the opposite order 2164 * elsewhere. 2165 */ 2166 mutex_exit(&zcw->zcw_lock); 2167 mutex_enter(&zilog->zl_issuer_lock); 2168 mutex_enter(&zcw->zcw_lock); 2169 2170 /* 2171 * Since we just dropped and re-acquired the commit waiter's 2172 * lock, we have to re-check to see if the waiter was marked 2173 * "done" during that process. If the waiter was marked "done", 2174 * the "lwb" pointer is no longer valid (it can be free'd after 2175 * the waiter is marked "done"), so without this check we could 2176 * wind up with a use-after-free error below. 2177 */ 2178 if (zcw->zcw_done) 2179 goto out; 2180 2181 ASSERT3P(lwb, ==, zcw->zcw_lwb); 2182 2183 /* 2184 * We've already checked this above, but since we hadn't acquired 2185 * the zilog's zl_issuer_lock, we have to perform this check a 2186 * second time while holding the lock. 2187 * 2188 * We don't need to hold the zl_lock since the lwb cannot transition 2189 * from OPENED to ISSUED while we hold the zl_issuer_lock. The lwb 2190 * _can_ transition from ISSUED to DONE, but it's OK to race with 2191 * that transition since we treat the lwb the same, whether it's in 2192 * the ISSUED or DONE states. 2193 * 2194 * The important thing, is we treat the lwb differently depending on 2195 * if it's ISSUED or OPENED, and block any other threads that might 2196 * attempt to issue this lwb. For that reason we hold the 2197 * zl_issuer_lock when checking the lwb_state; we must not call 2198 * zil_lwb_write_issue() if the lwb had already been issued. 2199 * 2200 * See the comment above the lwb_state_t structure definition for 2201 * more details on the lwb states, and locking requirements. 2202 */ 2203 if (lwb->lwb_state == LWB_STATE_ISSUED || 2204 lwb->lwb_state == LWB_STATE_DONE) 2205 goto out; 2206 2207 ASSERT3S(lwb->lwb_state, ==, LWB_STATE_OPENED); 2208 2209 /* 2210 * As described in the comments above zil_commit_waiter() and 2211 * zil_process_commit_list(), we need to issue this lwb's zio 2212 * since we've reached the commit waiter's timeout and it still 2213 * hasn't been issued. 2214 */ 2215 lwb_t *nlwb = zil_lwb_write_issue(zilog, lwb); 2216 2217 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_OPENED); 2218 2219 /* 2220 * Since the lwb's zio hadn't been issued by the time this thread 2221 * reached its timeout, we reset the zilog's "zl_cur_used" field 2222 * to influence the zil block size selection algorithm. 2223 * 2224 * By having to issue the lwb's zio here, it means the size of the 2225 * lwb was too large, given the incoming throughput of itxs. By 2226 * setting "zl_cur_used" to zero, we communicate this fact to the 2227 * block size selection algorithm, so it can take this informaiton 2228 * into account, and potentially select a smaller size for the 2229 * next lwb block that is allocated. 2230 */ 2231 zilog->zl_cur_used = 0; 2232 2233 if (nlwb == NULL) { 2234 /* 2235 * When zil_lwb_write_issue() returns NULL, this 2236 * indicates zio_alloc_zil() failed to allocate the 2237 * "next" lwb on-disk. When this occurs, the ZIL write 2238 * pipeline must be stalled; see the comment within the 2239 * zil_commit_writer_stall() function for more details. 2240 * 2241 * We must drop the commit waiter's lock prior to 2242 * calling zil_commit_writer_stall() or else we can wind 2243 * up with the following deadlock: 2244 * 2245 * - This thread is waiting for the txg to sync while 2246 * holding the waiter's lock; txg_wait_synced() is 2247 * used within txg_commit_writer_stall(). 2248 * 2249 * - The txg can't sync because it is waiting for this 2250 * lwb's zio callback to call dmu_tx_commit(). 2251 * 2252 * - The lwb's zio callback can't call dmu_tx_commit() 2253 * because it's blocked trying to acquire the waiter's 2254 * lock, which occurs prior to calling dmu_tx_commit() 2255 */ 2256 mutex_exit(&zcw->zcw_lock); 2257 zil_commit_writer_stall(zilog); 2258 mutex_enter(&zcw->zcw_lock); 2259 } 2260 2261 out: 2262 mutex_exit(&zilog->zl_issuer_lock); 2263 ASSERT(MUTEX_HELD(&zcw->zcw_lock)); 2264 } 2265 2266 /* 2267 * This function is responsible for performing the following two tasks: 2268 * 2269 * 1. its primary responsibility is to block until the given "commit 2270 * waiter" is considered "done". 2271 * 2272 * 2. its secondary responsibility is to issue the zio for the lwb that 2273 * the given "commit waiter" is waiting on, if this function has 2274 * waited "long enough" and the lwb is still in the "open" state. 2275 * 2276 * Given a sufficient amount of itxs being generated and written using 2277 * the ZIL, the lwb's zio will be issued via the zil_lwb_commit() 2278 * function. If this does not occur, this secondary responsibility will 2279 * ensure the lwb is issued even if there is not other synchronous 2280 * activity on the system. 2281 * 2282 * For more details, see zil_process_commit_list(); more specifically, 2283 * the comment at the bottom of that function. 2284 */ 2285 static void 2286 zil_commit_waiter(zilog_t *zilog, zil_commit_waiter_t *zcw) 2287 { 2288 ASSERT(!MUTEX_HELD(&zilog->zl_lock)); 2289 ASSERT(!MUTEX_HELD(&zilog->zl_issuer_lock)); 2290 ASSERT(spa_writeable(zilog->zl_spa)); 2291 2292 mutex_enter(&zcw->zcw_lock); 2293 2294 /* 2295 * The timeout is scaled based on the lwb latency to avoid 2296 * significantly impacting the latency of each individual itx. 2297 * For more details, see the comment at the bottom of the 2298 * zil_process_commit_list() function. 2299 */ 2300 int pct = MAX(zfs_commit_timeout_pct, 1); 2301 hrtime_t sleep = (zilog->zl_last_lwb_latency * pct) / 100; 2302 hrtime_t wakeup = gethrtime() + sleep; 2303 boolean_t timedout = B_FALSE; 2304 2305 while (!zcw->zcw_done) { 2306 ASSERT(MUTEX_HELD(&zcw->zcw_lock)); 2307 2308 lwb_t *lwb = zcw->zcw_lwb; 2309 2310 /* 2311 * Usually, the waiter will have a non-NULL lwb field here, 2312 * but it's possible for it to be NULL as a result of 2313 * zil_commit() racing with spa_sync(). 2314 * 2315 * When zil_clean() is called, it's possible for the itxg 2316 * list (which may be cleaned via a taskq) to contain 2317 * commit itxs. When this occurs, the commit waiters linked 2318 * off of these commit itxs will not be committed to an 2319 * lwb. Additionally, these commit waiters will not be 2320 * marked done until zil_commit_waiter_skip() is called via 2321 * zil_itxg_clean(). 2322 * 2323 * Thus, it's possible for this commit waiter (i.e. the 2324 * "zcw" variable) to be found in this "in between" state; 2325 * where it's "zcw_lwb" field is NULL, and it hasn't yet 2326 * been skipped, so it's "zcw_done" field is still B_FALSE. 2327 */ 2328 IMPLY(lwb != NULL, lwb->lwb_state != LWB_STATE_CLOSED); 2329 2330 if (lwb != NULL && lwb->lwb_state == LWB_STATE_OPENED) { 2331 ASSERT3B(timedout, ==, B_FALSE); 2332 2333 /* 2334 * If the lwb hasn't been issued yet, then we 2335 * need to wait with a timeout, in case this 2336 * function needs to issue the lwb after the 2337 * timeout is reached; responsibility (2) from 2338 * the comment above this function. 2339 */ 2340 clock_t timeleft = cv_timedwait_hires(&zcw->zcw_cv, 2341 &zcw->zcw_lock, wakeup, USEC2NSEC(1), 2342 CALLOUT_FLAG_ABSOLUTE); 2343 2344 if (timeleft >= 0 || zcw->zcw_done) 2345 continue; 2346 2347 timedout = B_TRUE; 2348 zil_commit_waiter_timeout(zilog, zcw); 2349 2350 if (!zcw->zcw_done) { 2351 /* 2352 * If the commit waiter has already been 2353 * marked "done", it's possible for the 2354 * waiter's lwb structure to have already 2355 * been freed. Thus, we can only reliably 2356 * make these assertions if the waiter 2357 * isn't done. 2358 */ 2359 ASSERT3P(lwb, ==, zcw->zcw_lwb); 2360 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_OPENED); 2361 } 2362 } else { 2363 /* 2364 * If the lwb isn't open, then it must have already 2365 * been issued. In that case, there's no need to 2366 * use a timeout when waiting for the lwb to 2367 * complete. 2368 * 2369 * Additionally, if the lwb is NULL, the waiter 2370 * will soon be signalled and marked done via 2371 * zil_clean() and zil_itxg_clean(), so no timeout 2372 * is required. 2373 */ 2374 2375 IMPLY(lwb != NULL, 2376 lwb->lwb_state == LWB_STATE_ISSUED || 2377 lwb->lwb_state == LWB_STATE_DONE); 2378 cv_wait(&zcw->zcw_cv, &zcw->zcw_lock); 2379 } 2380 } 2381 2382 mutex_exit(&zcw->zcw_lock); 2383 } 2384 2385 static zil_commit_waiter_t * 2386 zil_alloc_commit_waiter() 2387 { 2388 zil_commit_waiter_t *zcw = kmem_cache_alloc(zil_zcw_cache, KM_SLEEP); 2389 2390 cv_init(&zcw->zcw_cv, NULL, CV_DEFAULT, NULL); 2391 mutex_init(&zcw->zcw_lock, NULL, MUTEX_DEFAULT, NULL); 2392 list_link_init(&zcw->zcw_node); 2393 zcw->zcw_lwb = NULL; 2394 zcw->zcw_done = B_FALSE; 2395 zcw->zcw_zio_error = 0; 2396 2397 return (zcw); 2398 } 2399 2400 static void 2401 zil_free_commit_waiter(zil_commit_waiter_t *zcw) 2402 { 2403 ASSERT(!list_link_active(&zcw->zcw_node)); 2404 ASSERT3P(zcw->zcw_lwb, ==, NULL); 2405 ASSERT3B(zcw->zcw_done, ==, B_TRUE); 2406 mutex_destroy(&zcw->zcw_lock); 2407 cv_destroy(&zcw->zcw_cv); 2408 kmem_cache_free(zil_zcw_cache, zcw); 2409 } 2410 2411 /* 2412 * This function is used to create a TX_COMMIT itx and assign it. This 2413 * way, it will be linked into the ZIL's list of synchronous itxs, and 2414 * then later committed to an lwb (or skipped) when 2415 * zil_process_commit_list() is called. 2416 */ 2417 static void 2418 zil_commit_itx_assign(zilog_t *zilog, zil_commit_waiter_t *zcw) 2419 { 2420 dmu_tx_t *tx = dmu_tx_create(zilog->zl_os); 2421 VERIFY0(dmu_tx_assign(tx, TXG_WAIT)); 2422 2423 itx_t *itx = zil_itx_create(TX_COMMIT, sizeof (lr_t)); 2424 itx->itx_sync = B_TRUE; 2425 itx->itx_private = zcw; 2426 2427 zil_itx_assign(zilog, itx, tx); 2428 2429 dmu_tx_commit(tx); 2430 } 2431 2432 /* 2433 * Commit ZFS Intent Log transactions (itxs) to stable storage. 2434 * 2435 * When writing ZIL transactions to the on-disk representation of the 2436 * ZIL, the itxs are committed to a Log Write Block (lwb). Multiple 2437 * itxs can be committed to a single lwb. Once a lwb is written and 2438 * committed to stable storage (i.e. the lwb is written, and vdevs have 2439 * been flushed), each itx that was committed to that lwb is also 2440 * considered to be committed to stable storage. 2441 * 2442 * When an itx is committed to an lwb, the log record (lr_t) contained 2443 * by the itx is copied into the lwb's zio buffer, and once this buffer 2444 * is written to disk, it becomes an on-disk ZIL block. 2445 * 2446 * As itxs are generated, they're inserted into the ZIL's queue of 2447 * uncommitted itxs. The semantics of zil_commit() are such that it will 2448 * block until all itxs that were in the queue when it was called, are 2449 * committed to stable storage. 2450 * 2451 * If "foid" is zero, this means all "synchronous" and "asynchronous" 2452 * itxs, for all objects in the dataset, will be committed to stable 2453 * storage prior to zil_commit() returning. If "foid" is non-zero, all 2454 * "synchronous" itxs for all objects, but only "asynchronous" itxs 2455 * that correspond to the foid passed in, will be committed to stable 2456 * storage prior to zil_commit() returning. 2457 * 2458 * Generally speaking, when zil_commit() is called, the consumer doesn't 2459 * actually care about _all_ of the uncommitted itxs. Instead, they're 2460 * simply trying to waiting for a specific itx to be committed to disk, 2461 * but the interface(s) for interacting with the ZIL don't allow such 2462 * fine-grained communication. A better interface would allow a consumer 2463 * to create and assign an itx, and then pass a reference to this itx to 2464 * zil_commit(); such that zil_commit() would return as soon as that 2465 * specific itx was committed to disk (instead of waiting for _all_ 2466 * itxs to be committed). 2467 * 2468 * When a thread calls zil_commit() a special "commit itx" will be 2469 * generated, along with a corresponding "waiter" for this commit itx. 2470 * zil_commit() will wait on this waiter's CV, such that when the waiter 2471 * is marked done, and signalled, zil_commit() will return. 2472 * 2473 * This commit itx is inserted into the queue of uncommitted itxs. This 2474 * provides an easy mechanism for determining which itxs were in the 2475 * queue prior to zil_commit() having been called, and which itxs were 2476 * added after zil_commit() was called. 2477 * 2478 * The commit it is special; it doesn't have any on-disk representation. 2479 * When a commit itx is "committed" to an lwb, the waiter associated 2480 * with it is linked onto the lwb's list of waiters. Then, when that lwb 2481 * completes, each waiter on the lwb's list is marked done and signalled 2482 * -- allowing the thread waiting on the waiter to return from zil_commit(). 2483 * 2484 * It's important to point out a few critical factors that allow us 2485 * to make use of the commit itxs, commit waiters, per-lwb lists of 2486 * commit waiters, and zio completion callbacks like we're doing: 2487 * 2488 * 1. The list of waiters for each lwb is traversed, and each commit 2489 * waiter is marked "done" and signalled, in the zio completion 2490 * callback of the lwb's zio[*]. 2491 * 2492 * * Actually, the waiters are signalled in the zio completion 2493 * callback of the root zio for the DKIOCFLUSHWRITECACHE commands 2494 * that are sent to the vdevs upon completion of the lwb zio. 2495 * 2496 * 2. When the itxs are inserted into the ZIL's queue of uncommitted 2497 * itxs, the order in which they are inserted is preserved[*]; as 2498 * itxs are added to the queue, they are added to the tail of 2499 * in-memory linked lists. 2500 * 2501 * When committing the itxs to lwbs (to be written to disk), they 2502 * are committed in the same order in which the itxs were added to 2503 * the uncommitted queue's linked list(s); i.e. the linked list of 2504 * itxs to commit is traversed from head to tail, and each itx is 2505 * committed to an lwb in that order. 2506 * 2507 * * To clarify: 2508 * 2509 * - the order of "sync" itxs is preserved w.r.t. other 2510 * "sync" itxs, regardless of the corresponding objects. 2511 * - the order of "async" itxs is preserved w.r.t. other 2512 * "async" itxs corresponding to the same object. 2513 * - the order of "async" itxs is *not* preserved w.r.t. other 2514 * "async" itxs corresponding to different objects. 2515 * - the order of "sync" itxs w.r.t. "async" itxs (or vice 2516 * versa) is *not* preserved, even for itxs that correspond 2517 * to the same object. 2518 * 2519 * For more details, see: zil_itx_assign(), zil_async_to_sync(), 2520 * zil_get_commit_list(), and zil_process_commit_list(). 2521 * 2522 * 3. The lwbs represent a linked list of blocks on disk. Thus, any 2523 * lwb cannot be considered committed to stable storage, until its 2524 * "previous" lwb is also committed to stable storage. This fact, 2525 * coupled with the fact described above, means that itxs are 2526 * committed in (roughly) the order in which they were generated. 2527 * This is essential because itxs are dependent on prior itxs. 2528 * Thus, we *must not* deem an itx as being committed to stable 2529 * storage, until *all* prior itxs have also been committed to 2530 * stable storage. 2531 * 2532 * To enforce this ordering of lwb zio's, while still leveraging as 2533 * much of the underlying storage performance as possible, we rely 2534 * on two fundamental concepts: 2535 * 2536 * 1. The creation and issuance of lwb zio's is protected by 2537 * the zilog's "zl_issuer_lock", which ensures only a single 2538 * thread is creating and/or issuing lwb's at a time 2539 * 2. The "previous" lwb is a child of the "current" lwb 2540 * (leveraging the zio parent-child depenency graph) 2541 * 2542 * By relying on this parent-child zio relationship, we can have 2543 * many lwb zio's concurrently issued to the underlying storage, 2544 * but the order in which they complete will be the same order in 2545 * which they were created. 2546 */ 2547 void 2548 zil_commit(zilog_t *zilog, uint64_t foid) 2549 { 2550 /* 2551 * We should never attempt to call zil_commit on a snapshot for 2552 * a couple of reasons: 2553 * 2554 * 1. A snapshot may never be modified, thus it cannot have any 2555 * in-flight itxs that would have modified the dataset. 2556 * 2557 * 2. By design, when zil_commit() is called, a commit itx will 2558 * be assigned to this zilog; as a result, the zilog will be 2559 * dirtied. We must not dirty the zilog of a snapshot; there's 2560 * checks in the code that enforce this invariant, and will 2561 * cause a panic if it's not upheld. 2562 */ 2563 ASSERT3B(dmu_objset_is_snapshot(zilog->zl_os), ==, B_FALSE); 2564 2565 if (zilog->zl_sync == ZFS_SYNC_DISABLED) 2566 return; 2567 2568 if (!spa_writeable(zilog->zl_spa)) { 2569 /* 2570 * If the SPA is not writable, there should never be any 2571 * pending itxs waiting to be committed to disk. If that 2572 * weren't true, we'd skip writing those itxs out, and 2573 * would break the sematics of zil_commit(); thus, we're 2574 * verifying that truth before we return to the caller. 2575 */ 2576 ASSERT(list_is_empty(&zilog->zl_lwb_list)); 2577 ASSERT3P(zilog->zl_last_lwb_opened, ==, NULL); 2578 for (int i = 0; i < TXG_SIZE; i++) 2579 ASSERT3P(zilog->zl_itxg[i].itxg_itxs, ==, NULL); 2580 return; 2581 } 2582 2583 /* 2584 * If the ZIL is suspended, we don't want to dirty it by calling 2585 * zil_commit_itx_assign() below, nor can we write out 2586 * lwbs like would be done in zil_commit_write(). Thus, we 2587 * simply rely on txg_wait_synced() to maintain the necessary 2588 * semantics, and avoid calling those functions altogether. 2589 */ 2590 if (zilog->zl_suspend > 0) { 2591 txg_wait_synced(zilog->zl_dmu_pool, 0); 2592 return; 2593 } 2594 2595 zil_commit_impl(zilog, foid); 2596 } 2597 2598 void 2599 zil_commit_impl(zilog_t *zilog, uint64_t foid) 2600 { 2601 /* 2602 * Move the "async" itxs for the specified foid to the "sync" 2603 * queues, such that they will be later committed (or skipped) 2604 * to an lwb when zil_process_commit_list() is called. 2605 * 2606 * Since these "async" itxs must be committed prior to this 2607 * call to zil_commit returning, we must perform this operation 2608 * before we call zil_commit_itx_assign(). 2609 */ 2610 zil_async_to_sync(zilog, foid); 2611 2612 /* 2613 * We allocate a new "waiter" structure which will initially be 2614 * linked to the commit itx using the itx's "itx_private" field. 2615 * Since the commit itx doesn't represent any on-disk state, 2616 * when it's committed to an lwb, rather than copying the its 2617 * lr_t into the lwb's buffer, the commit itx's "waiter" will be 2618 * added to the lwb's list of waiters. Then, when the lwb is 2619 * committed to stable storage, each waiter in the lwb's list of 2620 * waiters will be marked "done", and signalled. 2621 * 2622 * We must create the waiter and assign the commit itx prior to 2623 * calling zil_commit_writer(), or else our specific commit itx 2624 * is not guaranteed to be committed to an lwb prior to calling 2625 * zil_commit_waiter(). 2626 */ 2627 zil_commit_waiter_t *zcw = zil_alloc_commit_waiter(); 2628 zil_commit_itx_assign(zilog, zcw); 2629 2630 zil_commit_writer(zilog, zcw); 2631 zil_commit_waiter(zilog, zcw); 2632 2633 if (zcw->zcw_zio_error != 0) { 2634 /* 2635 * If there was an error writing out the ZIL blocks that 2636 * this thread is waiting on, then we fallback to 2637 * relying on spa_sync() to write out the data this 2638 * thread is waiting on. Obviously this has performance 2639 * implications, but the expectation is for this to be 2640 * an exceptional case, and shouldn't occur often. 2641 */ 2642 DTRACE_PROBE2(zil__commit__io__error, 2643 zilog_t *, zilog, zil_commit_waiter_t *, zcw); 2644 txg_wait_synced(zilog->zl_dmu_pool, 0); 2645 } 2646 2647 zil_free_commit_waiter(zcw); 2648 } 2649 2650 /* 2651 * Called in syncing context to free committed log blocks and update log header. 2652 */ 2653 void 2654 zil_sync(zilog_t *zilog, dmu_tx_t *tx) 2655 { 2656 zil_header_t *zh = zil_header_in_syncing_context(zilog); 2657 uint64_t txg = dmu_tx_get_txg(tx); 2658 spa_t *spa = zilog->zl_spa; 2659 uint64_t *replayed_seq = &zilog->zl_replayed_seq[txg & TXG_MASK]; 2660 lwb_t *lwb; 2661 2662 /* 2663 * We don't zero out zl_destroy_txg, so make sure we don't try 2664 * to destroy it twice. 2665 */ 2666 if (spa_sync_pass(spa) != 1) 2667 return; 2668 2669 mutex_enter(&zilog->zl_lock); 2670 2671 ASSERT(zilog->zl_stop_sync == 0); 2672 2673 if (*replayed_seq != 0) { 2674 ASSERT(zh->zh_replay_seq < *replayed_seq); 2675 zh->zh_replay_seq = *replayed_seq; 2676 *replayed_seq = 0; 2677 } 2678 2679 if (zilog->zl_destroy_txg == txg) { 2680 blkptr_t blk = zh->zh_log; 2681 2682 ASSERT(list_head(&zilog->zl_lwb_list) == NULL); 2683 2684 bzero(zh, sizeof (zil_header_t)); 2685 bzero(zilog->zl_replayed_seq, sizeof (zilog->zl_replayed_seq)); 2686 2687 if (zilog->zl_keep_first) { 2688 /* 2689 * If this block was part of log chain that couldn't 2690 * be claimed because a device was missing during 2691 * zil_claim(), but that device later returns, 2692 * then this block could erroneously appear valid. 2693 * To guard against this, assign a new GUID to the new 2694 * log chain so it doesn't matter what blk points to. 2695 */ 2696 zil_init_log_chain(zilog, &blk); 2697 zh->zh_log = blk; 2698 } 2699 } 2700 2701 while ((lwb = list_head(&zilog->zl_lwb_list)) != NULL) { 2702 zh->zh_log = lwb->lwb_blk; 2703 if (lwb->lwb_buf != NULL || lwb->lwb_max_txg > txg) 2704 break; 2705 list_remove(&zilog->zl_lwb_list, lwb); 2706 zio_free(spa, txg, &lwb->lwb_blk); 2707 zil_free_lwb(zilog, lwb); 2708 2709 /* 2710 * If we don't have anything left in the lwb list then 2711 * we've had an allocation failure and we need to zero 2712 * out the zil_header blkptr so that we don't end 2713 * up freeing the same block twice. 2714 */ 2715 if (list_head(&zilog->zl_lwb_list) == NULL) 2716 BP_ZERO(&zh->zh_log); 2717 } 2718 mutex_exit(&zilog->zl_lock); 2719 } 2720 2721 /* ARGSUSED */ 2722 static int 2723 zil_lwb_cons(void *vbuf, void *unused, int kmflag) 2724 { 2725 lwb_t *lwb = vbuf; 2726 list_create(&lwb->lwb_waiters, sizeof (zil_commit_waiter_t), 2727 offsetof(zil_commit_waiter_t, zcw_node)); 2728 avl_create(&lwb->lwb_vdev_tree, zil_lwb_vdev_compare, 2729 sizeof (zil_vdev_node_t), offsetof(zil_vdev_node_t, zv_node)); 2730 mutex_init(&lwb->lwb_vdev_lock, NULL, MUTEX_DEFAULT, NULL); 2731 return (0); 2732 } 2733 2734 /* ARGSUSED */ 2735 static void 2736 zil_lwb_dest(void *vbuf, void *unused) 2737 { 2738 lwb_t *lwb = vbuf; 2739 mutex_destroy(&lwb->lwb_vdev_lock); 2740 avl_destroy(&lwb->lwb_vdev_tree); 2741 list_destroy(&lwb->lwb_waiters); 2742 } 2743 2744 void 2745 zil_init(void) 2746 { 2747 zil_lwb_cache = kmem_cache_create("zil_lwb_cache", 2748 sizeof (lwb_t), 0, zil_lwb_cons, zil_lwb_dest, NULL, NULL, NULL, 0); 2749 2750 zil_zcw_cache = kmem_cache_create("zil_zcw_cache", 2751 sizeof (zil_commit_waiter_t), 0, NULL, NULL, NULL, NULL, NULL, 0); 2752 } 2753 2754 void 2755 zil_fini(void) 2756 { 2757 kmem_cache_destroy(zil_zcw_cache); 2758 kmem_cache_destroy(zil_lwb_cache); 2759 } 2760 2761 void 2762 zil_set_sync(zilog_t *zilog, uint64_t sync) 2763 { 2764 zilog->zl_sync = sync; 2765 } 2766 2767 void 2768 zil_set_logbias(zilog_t *zilog, uint64_t logbias) 2769 { 2770 zilog->zl_logbias = logbias; 2771 } 2772 2773 zilog_t * 2774 zil_alloc(objset_t *os, zil_header_t *zh_phys) 2775 { 2776 zilog_t *zilog; 2777 2778 zilog = kmem_zalloc(sizeof (zilog_t), KM_SLEEP); 2779 2780 zilog->zl_header = zh_phys; 2781 zilog->zl_os = os; 2782 zilog->zl_spa = dmu_objset_spa(os); 2783 zilog->zl_dmu_pool = dmu_objset_pool(os); 2784 zilog->zl_destroy_txg = TXG_INITIAL - 1; 2785 zilog->zl_logbias = dmu_objset_logbias(os); 2786 zilog->zl_sync = dmu_objset_syncprop(os); 2787 zilog->zl_dirty_max_txg = 0; 2788 zilog->zl_last_lwb_opened = NULL; 2789 zilog->zl_last_lwb_latency = 0; 2790 2791 mutex_init(&zilog->zl_lock, NULL, MUTEX_DEFAULT, NULL); 2792 mutex_init(&zilog->zl_issuer_lock, NULL, MUTEX_DEFAULT, NULL); 2793 2794 for (int i = 0; i < TXG_SIZE; i++) { 2795 mutex_init(&zilog->zl_itxg[i].itxg_lock, NULL, 2796 MUTEX_DEFAULT, NULL); 2797 } 2798 2799 list_create(&zilog->zl_lwb_list, sizeof (lwb_t), 2800 offsetof(lwb_t, lwb_node)); 2801 2802 list_create(&zilog->zl_itx_commit_list, sizeof (itx_t), 2803 offsetof(itx_t, itx_node)); 2804 2805 cv_init(&zilog->zl_cv_suspend, NULL, CV_DEFAULT, NULL); 2806 2807 return (zilog); 2808 } 2809 2810 void 2811 zil_free(zilog_t *zilog) 2812 { 2813 zilog->zl_stop_sync = 1; 2814 2815 ASSERT0(zilog->zl_suspend); 2816 ASSERT0(zilog->zl_suspending); 2817 2818 ASSERT(list_is_empty(&zilog->zl_lwb_list)); 2819 list_destroy(&zilog->zl_lwb_list); 2820 2821 ASSERT(list_is_empty(&zilog->zl_itx_commit_list)); 2822 list_destroy(&zilog->zl_itx_commit_list); 2823 2824 for (int i = 0; i < TXG_SIZE; i++) { 2825 /* 2826 * It's possible for an itx to be generated that doesn't dirty 2827 * a txg (e.g. ztest TX_TRUNCATE). So there's no zil_clean() 2828 * callback to remove the entry. We remove those here. 2829 * 2830 * Also free up the ziltest itxs. 2831 */ 2832 if (zilog->zl_itxg[i].itxg_itxs) 2833 zil_itxg_clean(zilog->zl_itxg[i].itxg_itxs); 2834 mutex_destroy(&zilog->zl_itxg[i].itxg_lock); 2835 } 2836 2837 mutex_destroy(&zilog->zl_issuer_lock); 2838 mutex_destroy(&zilog->zl_lock); 2839 2840 cv_destroy(&zilog->zl_cv_suspend); 2841 2842 kmem_free(zilog, sizeof (zilog_t)); 2843 } 2844 2845 /* 2846 * Open an intent log. 2847 */ 2848 zilog_t * 2849 zil_open(objset_t *os, zil_get_data_t *get_data) 2850 { 2851 zilog_t *zilog = dmu_objset_zil(os); 2852 2853 ASSERT3P(zilog->zl_get_data, ==, NULL); 2854 ASSERT3P(zilog->zl_last_lwb_opened, ==, NULL); 2855 ASSERT(list_is_empty(&zilog->zl_lwb_list)); 2856 2857 zilog->zl_get_data = get_data; 2858 2859 return (zilog); 2860 } 2861 2862 /* 2863 * Close an intent log. 2864 */ 2865 void 2866 zil_close(zilog_t *zilog) 2867 { 2868 lwb_t *lwb; 2869 uint64_t txg; 2870 2871 if (!dmu_objset_is_snapshot(zilog->zl_os)) { 2872 zil_commit(zilog, 0); 2873 } else { 2874 ASSERT3P(list_tail(&zilog->zl_lwb_list), ==, NULL); 2875 ASSERT0(zilog->zl_dirty_max_txg); 2876 ASSERT3B(zilog_is_dirty(zilog), ==, B_FALSE); 2877 } 2878 2879 mutex_enter(&zilog->zl_lock); 2880 lwb = list_tail(&zilog->zl_lwb_list); 2881 if (lwb == NULL) 2882 txg = zilog->zl_dirty_max_txg; 2883 else 2884 txg = MAX(zilog->zl_dirty_max_txg, lwb->lwb_max_txg); 2885 mutex_exit(&zilog->zl_lock); 2886 2887 /* 2888 * We need to use txg_wait_synced() to wait long enough for the 2889 * ZIL to be clean, and to wait for all pending lwbs to be 2890 * written out. 2891 */ 2892 if (txg != 0) 2893 txg_wait_synced(zilog->zl_dmu_pool, txg); 2894 2895 if (zilog_is_dirty(zilog)) 2896 zfs_dbgmsg("zil (%p) is dirty, txg %llu", zilog, txg); 2897 VERIFY(!zilog_is_dirty(zilog)); 2898 2899 zilog->zl_get_data = NULL; 2900 2901 /* 2902 * We should have only one lwb left on the list; remove it now. 2903 */ 2904 mutex_enter(&zilog->zl_lock); 2905 lwb = list_head(&zilog->zl_lwb_list); 2906 if (lwb != NULL) { 2907 ASSERT3P(lwb, ==, list_tail(&zilog->zl_lwb_list)); 2908 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_ISSUED); 2909 list_remove(&zilog->zl_lwb_list, lwb); 2910 zio_buf_free(lwb->lwb_buf, lwb->lwb_sz); 2911 zil_free_lwb(zilog, lwb); 2912 } 2913 mutex_exit(&zilog->zl_lock); 2914 } 2915 2916 static char *suspend_tag = "zil suspending"; 2917 2918 /* 2919 * Suspend an intent log. While in suspended mode, we still honor 2920 * synchronous semantics, but we rely on txg_wait_synced() to do it. 2921 * On old version pools, we suspend the log briefly when taking a 2922 * snapshot so that it will have an empty intent log. 2923 * 2924 * Long holds are not really intended to be used the way we do here -- 2925 * held for such a short time. A concurrent caller of dsl_dataset_long_held() 2926 * could fail. Therefore we take pains to only put a long hold if it is 2927 * actually necessary. Fortunately, it will only be necessary if the 2928 * objset is currently mounted (or the ZVOL equivalent). In that case it 2929 * will already have a long hold, so we are not really making things any worse. 2930 * 2931 * Ideally, we would locate the existing long-holder (i.e. the zfsvfs_t or 2932 * zvol_state_t), and use their mechanism to prevent their hold from being 2933 * dropped (e.g. VFS_HOLD()). However, that would be even more pain for 2934 * very little gain. 2935 * 2936 * if cookiep == NULL, this does both the suspend & resume. 2937 * Otherwise, it returns with the dataset "long held", and the cookie 2938 * should be passed into zil_resume(). 2939 */ 2940 int 2941 zil_suspend(const char *osname, void **cookiep) 2942 { 2943 objset_t *os; 2944 zilog_t *zilog; 2945 const zil_header_t *zh; 2946 int error; 2947 2948 error = dmu_objset_hold(osname, suspend_tag, &os); 2949 if (error != 0) 2950 return (error); 2951 zilog = dmu_objset_zil(os); 2952 2953 mutex_enter(&zilog->zl_lock); 2954 zh = zilog->zl_header; 2955 2956 if (zh->zh_flags & ZIL_REPLAY_NEEDED) { /* unplayed log */ 2957 mutex_exit(&zilog->zl_lock); 2958 dmu_objset_rele(os, suspend_tag); 2959 return (SET_ERROR(EBUSY)); 2960 } 2961 2962 /* 2963 * Don't put a long hold in the cases where we can avoid it. This 2964 * is when there is no cookie so we are doing a suspend & resume 2965 * (i.e. called from zil_vdev_offline()), and there's nothing to do 2966 * for the suspend because it's already suspended, or there's no ZIL. 2967 */ 2968 if (cookiep == NULL && !zilog->zl_suspending && 2969 (zilog->zl_suspend > 0 || BP_IS_HOLE(&zh->zh_log))) { 2970 mutex_exit(&zilog->zl_lock); 2971 dmu_objset_rele(os, suspend_tag); 2972 return (0); 2973 } 2974 2975 dsl_dataset_long_hold(dmu_objset_ds(os), suspend_tag); 2976 dsl_pool_rele(dmu_objset_pool(os), suspend_tag); 2977 2978 zilog->zl_suspend++; 2979 2980 if (zilog->zl_suspend > 1) { 2981 /* 2982 * Someone else is already suspending it. 2983 * Just wait for them to finish. 2984 */ 2985 2986 while (zilog->zl_suspending) 2987 cv_wait(&zilog->zl_cv_suspend, &zilog->zl_lock); 2988 mutex_exit(&zilog->zl_lock); 2989 2990 if (cookiep == NULL) 2991 zil_resume(os); 2992 else 2993 *cookiep = os; 2994 return (0); 2995 } 2996 2997 /* 2998 * If there is no pointer to an on-disk block, this ZIL must not 2999 * be active (e.g. filesystem not mounted), so there's nothing 3000 * to clean up. 3001 */ 3002 if (BP_IS_HOLE(&zh->zh_log)) { 3003 ASSERT(cookiep != NULL); /* fast path already handled */ 3004 3005 *cookiep = os; 3006 mutex_exit(&zilog->zl_lock); 3007 return (0); 3008 } 3009 3010 zilog->zl_suspending = B_TRUE; 3011 mutex_exit(&zilog->zl_lock); 3012 3013 /* 3014 * We need to use zil_commit_impl to ensure we wait for all 3015 * LWB_STATE_OPENED and LWB_STATE_ISSUED lwb's to be committed 3016 * to disk before proceeding. If we used zil_commit instead, it 3017 * would just call txg_wait_synced(), because zl_suspend is set. 3018 * txg_wait_synced() doesn't wait for these lwb's to be 3019 * LWB_STATE_DONE before returning. 3020 */ 3021 zil_commit_impl(zilog, 0); 3022 3023 /* 3024 * Now that we've ensured all lwb's are LWB_STATE_DONE, we use 3025 * txg_wait_synced() to ensure the data from the zilog has 3026 * migrated to the main pool before calling zil_destroy(). 3027 */ 3028 txg_wait_synced(zilog->zl_dmu_pool, 0); 3029 3030 zil_destroy(zilog, B_FALSE); 3031 3032 mutex_enter(&zilog->zl_lock); 3033 zilog->zl_suspending = B_FALSE; 3034 cv_broadcast(&zilog->zl_cv_suspend); 3035 mutex_exit(&zilog->zl_lock); 3036 3037 if (cookiep == NULL) 3038 zil_resume(os); 3039 else 3040 *cookiep = os; 3041 return (0); 3042 } 3043 3044 void 3045 zil_resume(void *cookie) 3046 { 3047 objset_t *os = cookie; 3048 zilog_t *zilog = dmu_objset_zil(os); 3049 3050 mutex_enter(&zilog->zl_lock); 3051 ASSERT(zilog->zl_suspend != 0); 3052 zilog->zl_suspend--; 3053 mutex_exit(&zilog->zl_lock); 3054 dsl_dataset_long_rele(dmu_objset_ds(os), suspend_tag); 3055 dsl_dataset_rele(dmu_objset_ds(os), suspend_tag); 3056 } 3057 3058 typedef struct zil_replay_arg { 3059 zil_replay_func_t **zr_replay; 3060 void *zr_arg; 3061 boolean_t zr_byteswap; 3062 char *zr_lr; 3063 } zil_replay_arg_t; 3064 3065 static int 3066 zil_replay_error(zilog_t *zilog, lr_t *lr, int error) 3067 { 3068 char name[ZFS_MAX_DATASET_NAME_LEN]; 3069 3070 zilog->zl_replaying_seq--; /* didn't actually replay this one */ 3071 3072 dmu_objset_name(zilog->zl_os, name); 3073 3074 cmn_err(CE_WARN, "ZFS replay transaction error %d, " 3075 "dataset %s, seq 0x%llx, txtype %llu %s\n", error, name, 3076 (u_longlong_t)lr->lrc_seq, 3077 (u_longlong_t)(lr->lrc_txtype & ~TX_CI), 3078 (lr->lrc_txtype & TX_CI) ? "CI" : ""); 3079 3080 return (error); 3081 } 3082 3083 static int 3084 zil_replay_log_record(zilog_t *zilog, lr_t *lr, void *zra, uint64_t claim_txg) 3085 { 3086 zil_replay_arg_t *zr = zra; 3087 const zil_header_t *zh = zilog->zl_header; 3088 uint64_t reclen = lr->lrc_reclen; 3089 uint64_t txtype = lr->lrc_txtype; 3090 int error = 0; 3091 3092 zilog->zl_replaying_seq = lr->lrc_seq; 3093 3094 if (lr->lrc_seq <= zh->zh_replay_seq) /* already replayed */ 3095 return (0); 3096 3097 if (lr->lrc_txg < claim_txg) /* already committed */ 3098 return (0); 3099 3100 /* Strip case-insensitive bit, still present in log record */ 3101 txtype &= ~TX_CI; 3102 3103 if (txtype == 0 || txtype >= TX_MAX_TYPE) 3104 return (zil_replay_error(zilog, lr, EINVAL)); 3105 3106 /* 3107 * If this record type can be logged out of order, the object 3108 * (lr_foid) may no longer exist. That's legitimate, not an error. 3109 */ 3110 if (TX_OOO(txtype)) { 3111 error = dmu_object_info(zilog->zl_os, 3112 ((lr_ooo_t *)lr)->lr_foid, NULL); 3113 if (error == ENOENT || error == EEXIST) 3114 return (0); 3115 } 3116 3117 /* 3118 * Make a copy of the data so we can revise and extend it. 3119 */ 3120 bcopy(lr, zr->zr_lr, reclen); 3121 3122 /* 3123 * If this is a TX_WRITE with a blkptr, suck in the data. 3124 */ 3125 if (txtype == TX_WRITE && reclen == sizeof (lr_write_t)) { 3126 error = zil_read_log_data(zilog, (lr_write_t *)lr, 3127 zr->zr_lr + reclen); 3128 if (error != 0) 3129 return (zil_replay_error(zilog, lr, error)); 3130 } 3131 3132 /* 3133 * The log block containing this lr may have been byteswapped 3134 * so that we can easily examine common fields like lrc_txtype. 3135 * However, the log is a mix of different record types, and only the 3136 * replay vectors know how to byteswap their records. Therefore, if 3137 * the lr was byteswapped, undo it before invoking the replay vector. 3138 */ 3139 if (zr->zr_byteswap) 3140 byteswap_uint64_array(zr->zr_lr, reclen); 3141 3142 /* 3143 * We must now do two things atomically: replay this log record, 3144 * and update the log header sequence number to reflect the fact that 3145 * we did so. At the end of each replay function the sequence number 3146 * is updated if we are in replay mode. 3147 */ 3148 error = zr->zr_replay[txtype](zr->zr_arg, zr->zr_lr, zr->zr_byteswap); 3149 if (error != 0) { 3150 /* 3151 * The DMU's dnode layer doesn't see removes until the txg 3152 * commits, so a subsequent claim can spuriously fail with 3153 * EEXIST. So if we receive any error we try syncing out 3154 * any removes then retry the transaction. Note that we 3155 * specify B_FALSE for byteswap now, so we don't do it twice. 3156 */ 3157 txg_wait_synced(spa_get_dsl(zilog->zl_spa), 0); 3158 error = zr->zr_replay[txtype](zr->zr_arg, zr->zr_lr, B_FALSE); 3159 if (error != 0) 3160 return (zil_replay_error(zilog, lr, error)); 3161 } 3162 return (0); 3163 } 3164 3165 /* ARGSUSED */ 3166 static int 3167 zil_incr_blks(zilog_t *zilog, blkptr_t *bp, void *arg, uint64_t claim_txg) 3168 { 3169 zilog->zl_replay_blks++; 3170 3171 return (0); 3172 } 3173 3174 /* 3175 * If this dataset has a non-empty intent log, replay it and destroy it. 3176 */ 3177 void 3178 zil_replay(objset_t *os, void *arg, zil_replay_func_t *replay_func[TX_MAX_TYPE]) 3179 { 3180 zilog_t *zilog = dmu_objset_zil(os); 3181 const zil_header_t *zh = zilog->zl_header; 3182 zil_replay_arg_t zr; 3183 3184 if ((zh->zh_flags & ZIL_REPLAY_NEEDED) == 0) { 3185 zil_destroy(zilog, B_TRUE); 3186 return; 3187 } 3188 3189 zr.zr_replay = replay_func; 3190 zr.zr_arg = arg; 3191 zr.zr_byteswap = BP_SHOULD_BYTESWAP(&zh->zh_log); 3192 zr.zr_lr = kmem_alloc(2 * SPA_MAXBLOCKSIZE, KM_SLEEP); 3193 3194 /* 3195 * Wait for in-progress removes to sync before starting replay. 3196 */ 3197 txg_wait_synced(zilog->zl_dmu_pool, 0); 3198 3199 zilog->zl_replay = B_TRUE; 3200 zilog->zl_replay_time = ddi_get_lbolt(); 3201 ASSERT(zilog->zl_replay_blks == 0); 3202 (void) zil_parse(zilog, zil_incr_blks, zil_replay_log_record, &zr, 3203 zh->zh_claim_txg); 3204 kmem_free(zr.zr_lr, 2 * SPA_MAXBLOCKSIZE); 3205 3206 zil_destroy(zilog, B_FALSE); 3207 txg_wait_synced(zilog->zl_dmu_pool, zilog->zl_destroy_txg); 3208 zilog->zl_replay = B_FALSE; 3209 } 3210 3211 boolean_t 3212 zil_replaying(zilog_t *zilog, dmu_tx_t *tx) 3213 { 3214 if (zilog->zl_sync == ZFS_SYNC_DISABLED) 3215 return (B_TRUE); 3216 3217 if (zilog->zl_replay) { 3218 dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx); 3219 zilog->zl_replayed_seq[dmu_tx_get_txg(tx) & TXG_MASK] = 3220 zilog->zl_replaying_seq; 3221 return (B_TRUE); 3222 } 3223 3224 return (B_FALSE); 3225 } 3226 3227 /* ARGSUSED */ 3228 int 3229 zil_reset(const char *osname, void *arg) 3230 { 3231 int error; 3232 3233 error = zil_suspend(osname, NULL); 3234 if (error != 0) 3235 return (SET_ERROR(EEXIST)); 3236 return (0); 3237 } 3238