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 https://opensource.org/licenses/CDDL-1.0. 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, 2018 by Delphix. All rights reserved. 24 * Copyright (c) 2014 Integros [integros.com] 25 * Copyright (c) 2018 Datto Inc. 26 */ 27 28 /* Portions Copyright 2010 Robert Milkowski */ 29 30 #include <sys/zfs_context.h> 31 #include <sys/spa.h> 32 #include <sys/spa_impl.h> 33 #include <sys/dmu.h> 34 #include <sys/zap.h> 35 #include <sys/arc.h> 36 #include <sys/stat.h> 37 #include <sys/zil.h> 38 #include <sys/zil_impl.h> 39 #include <sys/dsl_dataset.h> 40 #include <sys/vdev_impl.h> 41 #include <sys/dmu_tx.h> 42 #include <sys/dsl_pool.h> 43 #include <sys/metaslab.h> 44 #include <sys/trace_zfs.h> 45 #include <sys/abd.h> 46 #include <sys/wmsum.h> 47 48 /* 49 * The ZFS Intent Log (ZIL) saves "transaction records" (itxs) of system 50 * calls that change the file system. Each itx has enough information to 51 * be able to replay them after a system crash, power loss, or 52 * equivalent failure mode. These are stored in memory until either: 53 * 54 * 1. they are committed to the pool by the DMU transaction group 55 * (txg), at which point they can be discarded; or 56 * 2. they are committed to the on-disk ZIL for the dataset being 57 * modified (e.g. due to an fsync, O_DSYNC, or other synchronous 58 * requirement). 59 * 60 * In the event of a crash or power loss, the itxs contained by each 61 * dataset's on-disk ZIL will be replayed when that dataset is first 62 * instantiated (e.g. if the dataset is a normal filesystem, when it is 63 * first mounted). 64 * 65 * As hinted at above, there is one ZIL per dataset (both the in-memory 66 * representation, and the on-disk representation). The on-disk format 67 * consists of 3 parts: 68 * 69 * - a single, per-dataset, ZIL header; which points to a chain of 70 * - zero or more ZIL blocks; each of which contains 71 * - zero or more ZIL records 72 * 73 * A ZIL record holds the information necessary to replay a single 74 * system call transaction. A ZIL block can hold many ZIL records, and 75 * the blocks are chained together, similarly to a singly linked list. 76 * 77 * Each ZIL block contains a block pointer (blkptr_t) to the next ZIL 78 * block in the chain, and the ZIL header points to the first block in 79 * the chain. 80 * 81 * Note, there is not a fixed place in the pool to hold these ZIL 82 * blocks; they are dynamically allocated and freed as needed from the 83 * blocks available on the pool, though they can be preferentially 84 * allocated from a dedicated "log" vdev. 85 */ 86 87 /* 88 * This controls the amount of time that a ZIL block (lwb) will remain 89 * "open" when it isn't "full", and it has a thread waiting for it to be 90 * committed to stable storage. Please refer to the zil_commit_waiter() 91 * function (and the comments within it) for more details. 92 */ 93 static int zfs_commit_timeout_pct = 5; 94 95 /* 96 * See zil.h for more information about these fields. 97 */ 98 static zil_kstat_values_t zil_stats = { 99 { "zil_commit_count", KSTAT_DATA_UINT64 }, 100 { "zil_commit_writer_count", KSTAT_DATA_UINT64 }, 101 { "zil_itx_count", KSTAT_DATA_UINT64 }, 102 { "zil_itx_indirect_count", KSTAT_DATA_UINT64 }, 103 { "zil_itx_indirect_bytes", KSTAT_DATA_UINT64 }, 104 { "zil_itx_copied_count", KSTAT_DATA_UINT64 }, 105 { "zil_itx_copied_bytes", KSTAT_DATA_UINT64 }, 106 { "zil_itx_needcopy_count", KSTAT_DATA_UINT64 }, 107 { "zil_itx_needcopy_bytes", KSTAT_DATA_UINT64 }, 108 { "zil_itx_metaslab_normal_count", KSTAT_DATA_UINT64 }, 109 { "zil_itx_metaslab_normal_bytes", KSTAT_DATA_UINT64 }, 110 { "zil_itx_metaslab_slog_count", KSTAT_DATA_UINT64 }, 111 { "zil_itx_metaslab_slog_bytes", KSTAT_DATA_UINT64 }, 112 }; 113 114 static zil_sums_t zil_sums_global; 115 static kstat_t *zil_kstats_global; 116 117 /* 118 * Disable intent logging replay. This global ZIL switch affects all pools. 119 */ 120 int zil_replay_disable = 0; 121 122 /* 123 * Disable the DKIOCFLUSHWRITECACHE commands that are normally sent to 124 * the disk(s) by the ZIL after an LWB write has completed. Setting this 125 * will cause ZIL corruption on power loss if a volatile out-of-order 126 * write cache is enabled. 127 */ 128 static int zil_nocacheflush = 0; 129 130 /* 131 * Limit SLOG write size per commit executed with synchronous priority. 132 * Any writes above that will be executed with lower (asynchronous) priority 133 * to limit potential SLOG device abuse by single active ZIL writer. 134 */ 135 static unsigned long zil_slog_bulk = 768 * 1024; 136 137 static kmem_cache_t *zil_lwb_cache; 138 static kmem_cache_t *zil_zcw_cache; 139 140 #define LWB_EMPTY(lwb) ((BP_GET_LSIZE(&lwb->lwb_blk) - \ 141 sizeof (zil_chain_t)) == (lwb->lwb_sz - lwb->lwb_nused)) 142 143 static int 144 zil_bp_compare(const void *x1, const void *x2) 145 { 146 const dva_t *dva1 = &((zil_bp_node_t *)x1)->zn_dva; 147 const dva_t *dva2 = &((zil_bp_node_t *)x2)->zn_dva; 148 149 int cmp = TREE_CMP(DVA_GET_VDEV(dva1), DVA_GET_VDEV(dva2)); 150 if (likely(cmp)) 151 return (cmp); 152 153 return (TREE_CMP(DVA_GET_OFFSET(dva1), DVA_GET_OFFSET(dva2))); 154 } 155 156 static void 157 zil_bp_tree_init(zilog_t *zilog) 158 { 159 avl_create(&zilog->zl_bp_tree, zil_bp_compare, 160 sizeof (zil_bp_node_t), offsetof(zil_bp_node_t, zn_node)); 161 } 162 163 static void 164 zil_bp_tree_fini(zilog_t *zilog) 165 { 166 avl_tree_t *t = &zilog->zl_bp_tree; 167 zil_bp_node_t *zn; 168 void *cookie = NULL; 169 170 while ((zn = avl_destroy_nodes(t, &cookie)) != NULL) 171 kmem_free(zn, sizeof (zil_bp_node_t)); 172 173 avl_destroy(t); 174 } 175 176 int 177 zil_bp_tree_add(zilog_t *zilog, const blkptr_t *bp) 178 { 179 avl_tree_t *t = &zilog->zl_bp_tree; 180 const dva_t *dva; 181 zil_bp_node_t *zn; 182 avl_index_t where; 183 184 if (BP_IS_EMBEDDED(bp)) 185 return (0); 186 187 dva = BP_IDENTITY(bp); 188 189 if (avl_find(t, dva, &where) != NULL) 190 return (SET_ERROR(EEXIST)); 191 192 zn = kmem_alloc(sizeof (zil_bp_node_t), KM_SLEEP); 193 zn->zn_dva = *dva; 194 avl_insert(t, zn, where); 195 196 return (0); 197 } 198 199 static zil_header_t * 200 zil_header_in_syncing_context(zilog_t *zilog) 201 { 202 return ((zil_header_t *)zilog->zl_header); 203 } 204 205 static void 206 zil_init_log_chain(zilog_t *zilog, blkptr_t *bp) 207 { 208 zio_cksum_t *zc = &bp->blk_cksum; 209 210 (void) random_get_pseudo_bytes((void *)&zc->zc_word[ZIL_ZC_GUID_0], 211 sizeof (zc->zc_word[ZIL_ZC_GUID_0])); 212 (void) random_get_pseudo_bytes((void *)&zc->zc_word[ZIL_ZC_GUID_1], 213 sizeof (zc->zc_word[ZIL_ZC_GUID_1])); 214 zc->zc_word[ZIL_ZC_OBJSET] = dmu_objset_id(zilog->zl_os); 215 zc->zc_word[ZIL_ZC_SEQ] = 1ULL; 216 } 217 218 static int 219 zil_kstats_global_update(kstat_t *ksp, int rw) 220 { 221 zil_kstat_values_t *zs = ksp->ks_data; 222 ASSERT3P(&zil_stats, ==, zs); 223 224 if (rw == KSTAT_WRITE) { 225 return (SET_ERROR(EACCES)); 226 } 227 228 zil_kstat_values_update(zs, &zil_sums_global); 229 230 return (0); 231 } 232 233 /* 234 * Read a log block and make sure it's valid. 235 */ 236 static int 237 zil_read_log_block(zilog_t *zilog, boolean_t decrypt, const blkptr_t *bp, 238 blkptr_t *nbp, void *dst, char **end) 239 { 240 enum zio_flag zio_flags = ZIO_FLAG_CANFAIL; 241 arc_flags_t aflags = ARC_FLAG_WAIT; 242 arc_buf_t *abuf = NULL; 243 zbookmark_phys_t zb; 244 int error; 245 246 if (zilog->zl_header->zh_claim_txg == 0) 247 zio_flags |= ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SCRUB; 248 249 if (!(zilog->zl_header->zh_flags & ZIL_CLAIM_LR_SEQ_VALID)) 250 zio_flags |= ZIO_FLAG_SPECULATIVE; 251 252 if (!decrypt) 253 zio_flags |= ZIO_FLAG_RAW; 254 255 SET_BOOKMARK(&zb, bp->blk_cksum.zc_word[ZIL_ZC_OBJSET], 256 ZB_ZIL_OBJECT, ZB_ZIL_LEVEL, bp->blk_cksum.zc_word[ZIL_ZC_SEQ]); 257 258 error = arc_read(NULL, zilog->zl_spa, bp, arc_getbuf_func, 259 &abuf, ZIO_PRIORITY_SYNC_READ, zio_flags, &aflags, &zb); 260 261 if (error == 0) { 262 zio_cksum_t cksum = bp->blk_cksum; 263 264 /* 265 * Validate the checksummed log block. 266 * 267 * Sequence numbers should be... sequential. The checksum 268 * verifier for the next block should be bp's checksum plus 1. 269 * 270 * Also check the log chain linkage and size used. 271 */ 272 cksum.zc_word[ZIL_ZC_SEQ]++; 273 274 if (BP_GET_CHECKSUM(bp) == ZIO_CHECKSUM_ZILOG2) { 275 zil_chain_t *zilc = abuf->b_data; 276 char *lr = (char *)(zilc + 1); 277 uint64_t len = zilc->zc_nused - sizeof (zil_chain_t); 278 279 if (memcmp(&cksum, &zilc->zc_next_blk.blk_cksum, 280 sizeof (cksum)) || BP_IS_HOLE(&zilc->zc_next_blk)) { 281 error = SET_ERROR(ECKSUM); 282 } else { 283 ASSERT3U(len, <=, SPA_OLD_MAXBLOCKSIZE); 284 memcpy(dst, lr, len); 285 *end = (char *)dst + len; 286 *nbp = zilc->zc_next_blk; 287 } 288 } else { 289 char *lr = abuf->b_data; 290 uint64_t size = BP_GET_LSIZE(bp); 291 zil_chain_t *zilc = (zil_chain_t *)(lr + size) - 1; 292 293 if (memcmp(&cksum, &zilc->zc_next_blk.blk_cksum, 294 sizeof (cksum)) || BP_IS_HOLE(&zilc->zc_next_blk) || 295 (zilc->zc_nused > (size - sizeof (*zilc)))) { 296 error = SET_ERROR(ECKSUM); 297 } else { 298 ASSERT3U(zilc->zc_nused, <=, 299 SPA_OLD_MAXBLOCKSIZE); 300 memcpy(dst, lr, zilc->zc_nused); 301 *end = (char *)dst + zilc->zc_nused; 302 *nbp = zilc->zc_next_blk; 303 } 304 } 305 306 arc_buf_destroy(abuf, &abuf); 307 } 308 309 return (error); 310 } 311 312 /* 313 * Read a TX_WRITE log data block. 314 */ 315 static int 316 zil_read_log_data(zilog_t *zilog, const lr_write_t *lr, void *wbuf) 317 { 318 enum zio_flag zio_flags = ZIO_FLAG_CANFAIL; 319 const blkptr_t *bp = &lr->lr_blkptr; 320 arc_flags_t aflags = ARC_FLAG_WAIT; 321 arc_buf_t *abuf = NULL; 322 zbookmark_phys_t zb; 323 int error; 324 325 if (BP_IS_HOLE(bp)) { 326 if (wbuf != NULL) 327 memset(wbuf, 0, MAX(BP_GET_LSIZE(bp), lr->lr_length)); 328 return (0); 329 } 330 331 if (zilog->zl_header->zh_claim_txg == 0) 332 zio_flags |= ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SCRUB; 333 334 /* 335 * If we are not using the resulting data, we are just checking that 336 * it hasn't been corrupted so we don't need to waste CPU time 337 * decompressing and decrypting it. 338 */ 339 if (wbuf == NULL) 340 zio_flags |= ZIO_FLAG_RAW; 341 342 SET_BOOKMARK(&zb, dmu_objset_id(zilog->zl_os), lr->lr_foid, 343 ZB_ZIL_LEVEL, lr->lr_offset / BP_GET_LSIZE(bp)); 344 345 error = arc_read(NULL, zilog->zl_spa, bp, arc_getbuf_func, &abuf, 346 ZIO_PRIORITY_SYNC_READ, zio_flags, &aflags, &zb); 347 348 if (error == 0) { 349 if (wbuf != NULL) 350 memcpy(wbuf, abuf->b_data, arc_buf_size(abuf)); 351 arc_buf_destroy(abuf, &abuf); 352 } 353 354 return (error); 355 } 356 357 void 358 zil_sums_init(zil_sums_t *zs) 359 { 360 wmsum_init(&zs->zil_commit_count, 0); 361 wmsum_init(&zs->zil_commit_writer_count, 0); 362 wmsum_init(&zs->zil_itx_count, 0); 363 wmsum_init(&zs->zil_itx_indirect_count, 0); 364 wmsum_init(&zs->zil_itx_indirect_bytes, 0); 365 wmsum_init(&zs->zil_itx_copied_count, 0); 366 wmsum_init(&zs->zil_itx_copied_bytes, 0); 367 wmsum_init(&zs->zil_itx_needcopy_count, 0); 368 wmsum_init(&zs->zil_itx_needcopy_bytes, 0); 369 wmsum_init(&zs->zil_itx_metaslab_normal_count, 0); 370 wmsum_init(&zs->zil_itx_metaslab_normal_bytes, 0); 371 wmsum_init(&zs->zil_itx_metaslab_slog_count, 0); 372 wmsum_init(&zs->zil_itx_metaslab_slog_bytes, 0); 373 } 374 375 void 376 zil_sums_fini(zil_sums_t *zs) 377 { 378 wmsum_fini(&zs->zil_commit_count); 379 wmsum_fini(&zs->zil_commit_writer_count); 380 wmsum_fini(&zs->zil_itx_count); 381 wmsum_fini(&zs->zil_itx_indirect_count); 382 wmsum_fini(&zs->zil_itx_indirect_bytes); 383 wmsum_fini(&zs->zil_itx_copied_count); 384 wmsum_fini(&zs->zil_itx_copied_bytes); 385 wmsum_fini(&zs->zil_itx_needcopy_count); 386 wmsum_fini(&zs->zil_itx_needcopy_bytes); 387 wmsum_fini(&zs->zil_itx_metaslab_normal_count); 388 wmsum_fini(&zs->zil_itx_metaslab_normal_bytes); 389 wmsum_fini(&zs->zil_itx_metaslab_slog_count); 390 wmsum_fini(&zs->zil_itx_metaslab_slog_bytes); 391 } 392 393 void 394 zil_kstat_values_update(zil_kstat_values_t *zs, zil_sums_t *zil_sums) 395 { 396 zs->zil_commit_count.value.ui64 = 397 wmsum_value(&zil_sums->zil_commit_count); 398 zs->zil_commit_writer_count.value.ui64 = 399 wmsum_value(&zil_sums->zil_commit_writer_count); 400 zs->zil_itx_count.value.ui64 = 401 wmsum_value(&zil_sums->zil_itx_count); 402 zs->zil_itx_indirect_count.value.ui64 = 403 wmsum_value(&zil_sums->zil_itx_indirect_count); 404 zs->zil_itx_indirect_bytes.value.ui64 = 405 wmsum_value(&zil_sums->zil_itx_indirect_bytes); 406 zs->zil_itx_copied_count.value.ui64 = 407 wmsum_value(&zil_sums->zil_itx_copied_count); 408 zs->zil_itx_copied_bytes.value.ui64 = 409 wmsum_value(&zil_sums->zil_itx_copied_bytes); 410 zs->zil_itx_needcopy_count.value.ui64 = 411 wmsum_value(&zil_sums->zil_itx_needcopy_count); 412 zs->zil_itx_needcopy_bytes.value.ui64 = 413 wmsum_value(&zil_sums->zil_itx_needcopy_bytes); 414 zs->zil_itx_metaslab_normal_count.value.ui64 = 415 wmsum_value(&zil_sums->zil_itx_metaslab_normal_count); 416 zs->zil_itx_metaslab_normal_bytes.value.ui64 = 417 wmsum_value(&zil_sums->zil_itx_metaslab_normal_bytes); 418 zs->zil_itx_metaslab_slog_count.value.ui64 = 419 wmsum_value(&zil_sums->zil_itx_metaslab_slog_count); 420 zs->zil_itx_metaslab_slog_bytes.value.ui64 = 421 wmsum_value(&zil_sums->zil_itx_metaslab_slog_bytes); 422 } 423 424 /* 425 * Parse the intent log, and call parse_func for each valid record within. 426 */ 427 int 428 zil_parse(zilog_t *zilog, zil_parse_blk_func_t *parse_blk_func, 429 zil_parse_lr_func_t *parse_lr_func, void *arg, uint64_t txg, 430 boolean_t decrypt) 431 { 432 const zil_header_t *zh = zilog->zl_header; 433 boolean_t claimed = !!zh->zh_claim_txg; 434 uint64_t claim_blk_seq = claimed ? zh->zh_claim_blk_seq : UINT64_MAX; 435 uint64_t claim_lr_seq = claimed ? zh->zh_claim_lr_seq : UINT64_MAX; 436 uint64_t max_blk_seq = 0; 437 uint64_t max_lr_seq = 0; 438 uint64_t blk_count = 0; 439 uint64_t lr_count = 0; 440 blkptr_t blk, next_blk = {{{{0}}}}; 441 char *lrbuf, *lrp; 442 int error = 0; 443 444 /* 445 * Old logs didn't record the maximum zh_claim_lr_seq. 446 */ 447 if (!(zh->zh_flags & ZIL_CLAIM_LR_SEQ_VALID)) 448 claim_lr_seq = UINT64_MAX; 449 450 /* 451 * Starting at the block pointed to by zh_log we read the log chain. 452 * For each block in the chain we strongly check that block to 453 * ensure its validity. We stop when an invalid block is found. 454 * For each block pointer in the chain we call parse_blk_func(). 455 * For each record in each valid block we call parse_lr_func(). 456 * If the log has been claimed, stop if we encounter a sequence 457 * number greater than the highest claimed sequence number. 458 */ 459 lrbuf = zio_buf_alloc(SPA_OLD_MAXBLOCKSIZE); 460 zil_bp_tree_init(zilog); 461 462 for (blk = zh->zh_log; !BP_IS_HOLE(&blk); blk = next_blk) { 463 uint64_t blk_seq = blk.blk_cksum.zc_word[ZIL_ZC_SEQ]; 464 int reclen; 465 char *end = NULL; 466 467 if (blk_seq > claim_blk_seq) 468 break; 469 470 error = parse_blk_func(zilog, &blk, arg, txg); 471 if (error != 0) 472 break; 473 ASSERT3U(max_blk_seq, <, blk_seq); 474 max_blk_seq = blk_seq; 475 blk_count++; 476 477 if (max_lr_seq == claim_lr_seq && max_blk_seq == claim_blk_seq) 478 break; 479 480 error = zil_read_log_block(zilog, decrypt, &blk, &next_blk, 481 lrbuf, &end); 482 if (error != 0) 483 break; 484 485 for (lrp = lrbuf; lrp < end; lrp += reclen) { 486 lr_t *lr = (lr_t *)lrp; 487 reclen = lr->lrc_reclen; 488 ASSERT3U(reclen, >=, sizeof (lr_t)); 489 if (lr->lrc_seq > claim_lr_seq) 490 goto done; 491 492 error = parse_lr_func(zilog, lr, arg, txg); 493 if (error != 0) 494 goto done; 495 ASSERT3U(max_lr_seq, <, lr->lrc_seq); 496 max_lr_seq = lr->lrc_seq; 497 lr_count++; 498 } 499 } 500 done: 501 zilog->zl_parse_error = error; 502 zilog->zl_parse_blk_seq = max_blk_seq; 503 zilog->zl_parse_lr_seq = max_lr_seq; 504 zilog->zl_parse_blk_count = blk_count; 505 zilog->zl_parse_lr_count = lr_count; 506 507 ASSERT(!claimed || !(zh->zh_flags & ZIL_CLAIM_LR_SEQ_VALID) || 508 (max_blk_seq == claim_blk_seq && max_lr_seq == claim_lr_seq) || 509 (decrypt && error == EIO)); 510 511 zil_bp_tree_fini(zilog); 512 zio_buf_free(lrbuf, SPA_OLD_MAXBLOCKSIZE); 513 514 return (error); 515 } 516 517 static int 518 zil_clear_log_block(zilog_t *zilog, const blkptr_t *bp, void *tx, 519 uint64_t first_txg) 520 { 521 (void) tx; 522 ASSERT(!BP_IS_HOLE(bp)); 523 524 /* 525 * As we call this function from the context of a rewind to a 526 * checkpoint, each ZIL block whose txg is later than the txg 527 * that we rewind to is invalid. Thus, we return -1 so 528 * zil_parse() doesn't attempt to read it. 529 */ 530 if (bp->blk_birth >= first_txg) 531 return (-1); 532 533 if (zil_bp_tree_add(zilog, bp) != 0) 534 return (0); 535 536 zio_free(zilog->zl_spa, first_txg, bp); 537 return (0); 538 } 539 540 static int 541 zil_noop_log_record(zilog_t *zilog, const lr_t *lrc, void *tx, 542 uint64_t first_txg) 543 { 544 (void) zilog, (void) lrc, (void) tx, (void) first_txg; 545 return (0); 546 } 547 548 static int 549 zil_claim_log_block(zilog_t *zilog, const blkptr_t *bp, void *tx, 550 uint64_t first_txg) 551 { 552 /* 553 * Claim log block if not already committed and not already claimed. 554 * If tx == NULL, just verify that the block is claimable. 555 */ 556 if (BP_IS_HOLE(bp) || bp->blk_birth < first_txg || 557 zil_bp_tree_add(zilog, bp) != 0) 558 return (0); 559 560 return (zio_wait(zio_claim(NULL, zilog->zl_spa, 561 tx == NULL ? 0 : first_txg, bp, spa_claim_notify, NULL, 562 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SCRUB))); 563 } 564 565 static int 566 zil_claim_log_record(zilog_t *zilog, const lr_t *lrc, void *tx, 567 uint64_t first_txg) 568 { 569 lr_write_t *lr = (lr_write_t *)lrc; 570 int error; 571 572 if (lrc->lrc_txtype != TX_WRITE) 573 return (0); 574 575 /* 576 * If the block is not readable, don't claim it. This can happen 577 * in normal operation when a log block is written to disk before 578 * some of the dmu_sync() blocks it points to. In this case, the 579 * transaction cannot have been committed to anyone (we would have 580 * waited for all writes to be stable first), so it is semantically 581 * correct to declare this the end of the log. 582 */ 583 if (lr->lr_blkptr.blk_birth >= first_txg) { 584 error = zil_read_log_data(zilog, lr, NULL); 585 if (error != 0) 586 return (error); 587 } 588 589 return (zil_claim_log_block(zilog, &lr->lr_blkptr, tx, first_txg)); 590 } 591 592 static int 593 zil_free_log_block(zilog_t *zilog, const blkptr_t *bp, void *tx, 594 uint64_t claim_txg) 595 { 596 (void) claim_txg; 597 598 zio_free(zilog->zl_spa, dmu_tx_get_txg(tx), bp); 599 600 return (0); 601 } 602 603 static int 604 zil_free_log_record(zilog_t *zilog, const lr_t *lrc, void *tx, 605 uint64_t claim_txg) 606 { 607 lr_write_t *lr = (lr_write_t *)lrc; 608 blkptr_t *bp = &lr->lr_blkptr; 609 610 /* 611 * If we previously claimed it, we need to free it. 612 */ 613 if (claim_txg != 0 && lrc->lrc_txtype == TX_WRITE && 614 bp->blk_birth >= claim_txg && zil_bp_tree_add(zilog, bp) == 0 && 615 !BP_IS_HOLE(bp)) 616 zio_free(zilog->zl_spa, dmu_tx_get_txg(tx), bp); 617 618 return (0); 619 } 620 621 static int 622 zil_lwb_vdev_compare(const void *x1, const void *x2) 623 { 624 const uint64_t v1 = ((zil_vdev_node_t *)x1)->zv_vdev; 625 const uint64_t v2 = ((zil_vdev_node_t *)x2)->zv_vdev; 626 627 return (TREE_CMP(v1, v2)); 628 } 629 630 static lwb_t * 631 zil_alloc_lwb(zilog_t *zilog, blkptr_t *bp, boolean_t slog, uint64_t txg, 632 boolean_t fastwrite) 633 { 634 lwb_t *lwb; 635 636 lwb = kmem_cache_alloc(zil_lwb_cache, KM_SLEEP); 637 lwb->lwb_zilog = zilog; 638 lwb->lwb_blk = *bp; 639 lwb->lwb_fastwrite = fastwrite; 640 lwb->lwb_slog = slog; 641 lwb->lwb_state = LWB_STATE_CLOSED; 642 lwb->lwb_buf = zio_buf_alloc(BP_GET_LSIZE(bp)); 643 lwb->lwb_max_txg = txg; 644 lwb->lwb_write_zio = NULL; 645 lwb->lwb_root_zio = NULL; 646 lwb->lwb_issued_timestamp = 0; 647 lwb->lwb_issued_txg = 0; 648 if (BP_GET_CHECKSUM(bp) == ZIO_CHECKSUM_ZILOG2) { 649 lwb->lwb_nused = sizeof (zil_chain_t); 650 lwb->lwb_sz = BP_GET_LSIZE(bp); 651 } else { 652 lwb->lwb_nused = 0; 653 lwb->lwb_sz = BP_GET_LSIZE(bp) - sizeof (zil_chain_t); 654 } 655 656 mutex_enter(&zilog->zl_lock); 657 list_insert_tail(&zilog->zl_lwb_list, lwb); 658 mutex_exit(&zilog->zl_lock); 659 660 ASSERT(!MUTEX_HELD(&lwb->lwb_vdev_lock)); 661 ASSERT(avl_is_empty(&lwb->lwb_vdev_tree)); 662 VERIFY(list_is_empty(&lwb->lwb_waiters)); 663 VERIFY(list_is_empty(&lwb->lwb_itxs)); 664 665 return (lwb); 666 } 667 668 static void 669 zil_free_lwb(zilog_t *zilog, lwb_t *lwb) 670 { 671 ASSERT(MUTEX_HELD(&zilog->zl_lock)); 672 ASSERT(!MUTEX_HELD(&lwb->lwb_vdev_lock)); 673 VERIFY(list_is_empty(&lwb->lwb_waiters)); 674 VERIFY(list_is_empty(&lwb->lwb_itxs)); 675 ASSERT(avl_is_empty(&lwb->lwb_vdev_tree)); 676 ASSERT3P(lwb->lwb_write_zio, ==, NULL); 677 ASSERT3P(lwb->lwb_root_zio, ==, NULL); 678 ASSERT3U(lwb->lwb_max_txg, <=, spa_syncing_txg(zilog->zl_spa)); 679 ASSERT(lwb->lwb_state == LWB_STATE_CLOSED || 680 lwb->lwb_state == LWB_STATE_FLUSH_DONE); 681 682 /* 683 * Clear the zilog's field to indicate this lwb is no longer 684 * valid, and prevent use-after-free errors. 685 */ 686 if (zilog->zl_last_lwb_opened == lwb) 687 zilog->zl_last_lwb_opened = NULL; 688 689 kmem_cache_free(zil_lwb_cache, lwb); 690 } 691 692 /* 693 * Called when we create in-memory log transactions so that we know 694 * to cleanup the itxs at the end of spa_sync(). 695 */ 696 static void 697 zilog_dirty(zilog_t *zilog, uint64_t txg) 698 { 699 dsl_pool_t *dp = zilog->zl_dmu_pool; 700 dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os); 701 702 ASSERT(spa_writeable(zilog->zl_spa)); 703 704 if (ds->ds_is_snapshot) 705 panic("dirtying snapshot!"); 706 707 if (txg_list_add(&dp->dp_dirty_zilogs, zilog, txg)) { 708 /* up the hold count until we can be written out */ 709 dmu_buf_add_ref(ds->ds_dbuf, zilog); 710 711 zilog->zl_dirty_max_txg = MAX(txg, zilog->zl_dirty_max_txg); 712 } 713 } 714 715 /* 716 * Determine if the zil is dirty in the specified txg. Callers wanting to 717 * ensure that the dirty state does not change must hold the itxg_lock for 718 * the specified txg. Holding the lock will ensure that the zil cannot be 719 * dirtied (zil_itx_assign) or cleaned (zil_clean) while we check its current 720 * state. 721 */ 722 static boolean_t __maybe_unused 723 zilog_is_dirty_in_txg(zilog_t *zilog, uint64_t txg) 724 { 725 dsl_pool_t *dp = zilog->zl_dmu_pool; 726 727 if (txg_list_member(&dp->dp_dirty_zilogs, zilog, txg & TXG_MASK)) 728 return (B_TRUE); 729 return (B_FALSE); 730 } 731 732 /* 733 * Determine if the zil is dirty. The zil is considered dirty if it has 734 * any pending itx records that have not been cleaned by zil_clean(). 735 */ 736 static boolean_t 737 zilog_is_dirty(zilog_t *zilog) 738 { 739 dsl_pool_t *dp = zilog->zl_dmu_pool; 740 741 for (int t = 0; t < TXG_SIZE; t++) { 742 if (txg_list_member(&dp->dp_dirty_zilogs, zilog, t)) 743 return (B_TRUE); 744 } 745 return (B_FALSE); 746 } 747 748 /* 749 * Its called in zil_commit context (zil_process_commit_list()/zil_create()). 750 * It activates SPA_FEATURE_ZILSAXATTR feature, if its enabled. 751 * Check dsl_dataset_feature_is_active to avoid txg_wait_synced() on every 752 * zil_commit. 753 */ 754 static void 755 zil_commit_activate_saxattr_feature(zilog_t *zilog) 756 { 757 dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os); 758 uint64_t txg = 0; 759 dmu_tx_t *tx = NULL; 760 761 if (spa_feature_is_enabled(zilog->zl_spa, 762 SPA_FEATURE_ZILSAXATTR) && 763 dmu_objset_type(zilog->zl_os) != DMU_OST_ZVOL && 764 !dsl_dataset_feature_is_active(ds, 765 SPA_FEATURE_ZILSAXATTR)) { 766 tx = dmu_tx_create(zilog->zl_os); 767 VERIFY0(dmu_tx_assign(tx, TXG_WAIT)); 768 dsl_dataset_dirty(ds, tx); 769 txg = dmu_tx_get_txg(tx); 770 771 mutex_enter(&ds->ds_lock); 772 ds->ds_feature_activation[SPA_FEATURE_ZILSAXATTR] = 773 (void *)B_TRUE; 774 mutex_exit(&ds->ds_lock); 775 dmu_tx_commit(tx); 776 txg_wait_synced(zilog->zl_dmu_pool, txg); 777 } 778 } 779 780 /* 781 * Create an on-disk intent log. 782 */ 783 static lwb_t * 784 zil_create(zilog_t *zilog) 785 { 786 const zil_header_t *zh = zilog->zl_header; 787 lwb_t *lwb = NULL; 788 uint64_t txg = 0; 789 dmu_tx_t *tx = NULL; 790 blkptr_t blk; 791 int error = 0; 792 boolean_t fastwrite = FALSE; 793 boolean_t slog = FALSE; 794 dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os); 795 796 797 /* 798 * Wait for any previous destroy to complete. 799 */ 800 txg_wait_synced(zilog->zl_dmu_pool, zilog->zl_destroy_txg); 801 802 ASSERT(zh->zh_claim_txg == 0); 803 ASSERT(zh->zh_replay_seq == 0); 804 805 blk = zh->zh_log; 806 807 /* 808 * Allocate an initial log block if: 809 * - there isn't one already 810 * - the existing block is the wrong endianness 811 */ 812 if (BP_IS_HOLE(&blk) || BP_SHOULD_BYTESWAP(&blk)) { 813 tx = dmu_tx_create(zilog->zl_os); 814 VERIFY0(dmu_tx_assign(tx, TXG_WAIT)); 815 dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx); 816 txg = dmu_tx_get_txg(tx); 817 818 if (!BP_IS_HOLE(&blk)) { 819 zio_free(zilog->zl_spa, txg, &blk); 820 BP_ZERO(&blk); 821 } 822 823 error = zio_alloc_zil(zilog->zl_spa, zilog->zl_os, txg, &blk, 824 ZIL_MIN_BLKSZ, &slog); 825 fastwrite = TRUE; 826 827 if (error == 0) 828 zil_init_log_chain(zilog, &blk); 829 } 830 831 /* 832 * Allocate a log write block (lwb) for the first log block. 833 */ 834 if (error == 0) 835 lwb = zil_alloc_lwb(zilog, &blk, slog, txg, fastwrite); 836 837 /* 838 * If we just allocated the first log block, commit our transaction 839 * and wait for zil_sync() to stuff the block pointer into zh_log. 840 * (zh is part of the MOS, so we cannot modify it in open context.) 841 */ 842 if (tx != NULL) { 843 /* 844 * If "zilsaxattr" feature is enabled on zpool, then activate 845 * it now when we're creating the ZIL chain. We can't wait with 846 * this until we write the first xattr log record because we 847 * need to wait for the feature activation to sync out. 848 */ 849 if (spa_feature_is_enabled(zilog->zl_spa, 850 SPA_FEATURE_ZILSAXATTR) && dmu_objset_type(zilog->zl_os) != 851 DMU_OST_ZVOL) { 852 mutex_enter(&ds->ds_lock); 853 ds->ds_feature_activation[SPA_FEATURE_ZILSAXATTR] = 854 (void *)B_TRUE; 855 mutex_exit(&ds->ds_lock); 856 } 857 858 dmu_tx_commit(tx); 859 txg_wait_synced(zilog->zl_dmu_pool, txg); 860 } else { 861 /* 862 * This branch covers the case where we enable the feature on a 863 * zpool that has existing ZIL headers. 864 */ 865 zil_commit_activate_saxattr_feature(zilog); 866 } 867 IMPLY(spa_feature_is_enabled(zilog->zl_spa, SPA_FEATURE_ZILSAXATTR) && 868 dmu_objset_type(zilog->zl_os) != DMU_OST_ZVOL, 869 dsl_dataset_feature_is_active(ds, SPA_FEATURE_ZILSAXATTR)); 870 871 ASSERT(error != 0 || memcmp(&blk, &zh->zh_log, sizeof (blk)) == 0); 872 IMPLY(error == 0, lwb != NULL); 873 874 return (lwb); 875 } 876 877 /* 878 * In one tx, free all log blocks and clear the log header. If keep_first 879 * is set, then we're replaying a log with no content. We want to keep the 880 * first block, however, so that the first synchronous transaction doesn't 881 * require a txg_wait_synced() in zil_create(). We don't need to 882 * txg_wait_synced() here either when keep_first is set, because both 883 * zil_create() and zil_destroy() will wait for any in-progress destroys 884 * to complete. 885 */ 886 void 887 zil_destroy(zilog_t *zilog, boolean_t keep_first) 888 { 889 const zil_header_t *zh = zilog->zl_header; 890 lwb_t *lwb; 891 dmu_tx_t *tx; 892 uint64_t txg; 893 894 /* 895 * Wait for any previous destroy to complete. 896 */ 897 txg_wait_synced(zilog->zl_dmu_pool, zilog->zl_destroy_txg); 898 899 zilog->zl_old_header = *zh; /* debugging aid */ 900 901 if (BP_IS_HOLE(&zh->zh_log)) 902 return; 903 904 tx = dmu_tx_create(zilog->zl_os); 905 VERIFY0(dmu_tx_assign(tx, TXG_WAIT)); 906 dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx); 907 txg = dmu_tx_get_txg(tx); 908 909 mutex_enter(&zilog->zl_lock); 910 911 ASSERT3U(zilog->zl_destroy_txg, <, txg); 912 zilog->zl_destroy_txg = txg; 913 zilog->zl_keep_first = keep_first; 914 915 if (!list_is_empty(&zilog->zl_lwb_list)) { 916 ASSERT(zh->zh_claim_txg == 0); 917 VERIFY(!keep_first); 918 while ((lwb = list_head(&zilog->zl_lwb_list)) != NULL) { 919 if (lwb->lwb_fastwrite) 920 metaslab_fastwrite_unmark(zilog->zl_spa, 921 &lwb->lwb_blk); 922 923 list_remove(&zilog->zl_lwb_list, lwb); 924 if (lwb->lwb_buf != NULL) 925 zio_buf_free(lwb->lwb_buf, lwb->lwb_sz); 926 zio_free(zilog->zl_spa, txg, &lwb->lwb_blk); 927 zil_free_lwb(zilog, lwb); 928 } 929 } else if (!keep_first) { 930 zil_destroy_sync(zilog, tx); 931 } 932 mutex_exit(&zilog->zl_lock); 933 934 dmu_tx_commit(tx); 935 } 936 937 void 938 zil_destroy_sync(zilog_t *zilog, dmu_tx_t *tx) 939 { 940 ASSERT(list_is_empty(&zilog->zl_lwb_list)); 941 (void) zil_parse(zilog, zil_free_log_block, 942 zil_free_log_record, tx, zilog->zl_header->zh_claim_txg, B_FALSE); 943 } 944 945 int 946 zil_claim(dsl_pool_t *dp, dsl_dataset_t *ds, void *txarg) 947 { 948 dmu_tx_t *tx = txarg; 949 zilog_t *zilog; 950 uint64_t first_txg; 951 zil_header_t *zh; 952 objset_t *os; 953 int error; 954 955 error = dmu_objset_own_obj(dp, ds->ds_object, 956 DMU_OST_ANY, B_FALSE, B_FALSE, FTAG, &os); 957 if (error != 0) { 958 /* 959 * EBUSY indicates that the objset is inconsistent, in which 960 * case it can not have a ZIL. 961 */ 962 if (error != EBUSY) { 963 cmn_err(CE_WARN, "can't open objset for %llu, error %u", 964 (unsigned long long)ds->ds_object, error); 965 } 966 967 return (0); 968 } 969 970 zilog = dmu_objset_zil(os); 971 zh = zil_header_in_syncing_context(zilog); 972 ASSERT3U(tx->tx_txg, ==, spa_first_txg(zilog->zl_spa)); 973 first_txg = spa_min_claim_txg(zilog->zl_spa); 974 975 /* 976 * If the spa_log_state is not set to be cleared, check whether 977 * the current uberblock is a checkpoint one and if the current 978 * header has been claimed before moving on. 979 * 980 * If the current uberblock is a checkpointed uberblock then 981 * one of the following scenarios took place: 982 * 983 * 1] We are currently rewinding to the checkpoint of the pool. 984 * 2] We crashed in the middle of a checkpoint rewind but we 985 * did manage to write the checkpointed uberblock to the 986 * vdev labels, so when we tried to import the pool again 987 * the checkpointed uberblock was selected from the import 988 * procedure. 989 * 990 * In both cases we want to zero out all the ZIL blocks, except 991 * the ones that have been claimed at the time of the checkpoint 992 * (their zh_claim_txg != 0). The reason is that these blocks 993 * may be corrupted since we may have reused their locations on 994 * disk after we took the checkpoint. 995 * 996 * We could try to set spa_log_state to SPA_LOG_CLEAR earlier 997 * when we first figure out whether the current uberblock is 998 * checkpointed or not. Unfortunately, that would discard all 999 * the logs, including the ones that are claimed, and we would 1000 * leak space. 1001 */ 1002 if (spa_get_log_state(zilog->zl_spa) == SPA_LOG_CLEAR || 1003 (zilog->zl_spa->spa_uberblock.ub_checkpoint_txg != 0 && 1004 zh->zh_claim_txg == 0)) { 1005 if (!BP_IS_HOLE(&zh->zh_log)) { 1006 (void) zil_parse(zilog, zil_clear_log_block, 1007 zil_noop_log_record, tx, first_txg, B_FALSE); 1008 } 1009 BP_ZERO(&zh->zh_log); 1010 if (os->os_encrypted) 1011 os->os_next_write_raw[tx->tx_txg & TXG_MASK] = B_TRUE; 1012 dsl_dataset_dirty(dmu_objset_ds(os), tx); 1013 dmu_objset_disown(os, B_FALSE, FTAG); 1014 return (0); 1015 } 1016 1017 /* 1018 * If we are not rewinding and opening the pool normally, then 1019 * the min_claim_txg should be equal to the first txg of the pool. 1020 */ 1021 ASSERT3U(first_txg, ==, spa_first_txg(zilog->zl_spa)); 1022 1023 /* 1024 * Claim all log blocks if we haven't already done so, and remember 1025 * the highest claimed sequence number. This ensures that if we can 1026 * read only part of the log now (e.g. due to a missing device), 1027 * but we can read the entire log later, we will not try to replay 1028 * or destroy beyond the last block we successfully claimed. 1029 */ 1030 ASSERT3U(zh->zh_claim_txg, <=, first_txg); 1031 if (zh->zh_claim_txg == 0 && !BP_IS_HOLE(&zh->zh_log)) { 1032 (void) zil_parse(zilog, zil_claim_log_block, 1033 zil_claim_log_record, tx, first_txg, B_FALSE); 1034 zh->zh_claim_txg = first_txg; 1035 zh->zh_claim_blk_seq = zilog->zl_parse_blk_seq; 1036 zh->zh_claim_lr_seq = zilog->zl_parse_lr_seq; 1037 if (zilog->zl_parse_lr_count || zilog->zl_parse_blk_count > 1) 1038 zh->zh_flags |= ZIL_REPLAY_NEEDED; 1039 zh->zh_flags |= ZIL_CLAIM_LR_SEQ_VALID; 1040 if (os->os_encrypted) 1041 os->os_next_write_raw[tx->tx_txg & TXG_MASK] = B_TRUE; 1042 dsl_dataset_dirty(dmu_objset_ds(os), tx); 1043 } 1044 1045 ASSERT3U(first_txg, ==, (spa_last_synced_txg(zilog->zl_spa) + 1)); 1046 dmu_objset_disown(os, B_FALSE, FTAG); 1047 return (0); 1048 } 1049 1050 /* 1051 * Check the log by walking the log chain. 1052 * Checksum errors are ok as they indicate the end of the chain. 1053 * Any other error (no device or read failure) returns an error. 1054 */ 1055 int 1056 zil_check_log_chain(dsl_pool_t *dp, dsl_dataset_t *ds, void *tx) 1057 { 1058 (void) dp; 1059 zilog_t *zilog; 1060 objset_t *os; 1061 blkptr_t *bp; 1062 int error; 1063 1064 ASSERT(tx == NULL); 1065 1066 error = dmu_objset_from_ds(ds, &os); 1067 if (error != 0) { 1068 cmn_err(CE_WARN, "can't open objset %llu, error %d", 1069 (unsigned long long)ds->ds_object, error); 1070 return (0); 1071 } 1072 1073 zilog = dmu_objset_zil(os); 1074 bp = (blkptr_t *)&zilog->zl_header->zh_log; 1075 1076 if (!BP_IS_HOLE(bp)) { 1077 vdev_t *vd; 1078 boolean_t valid = B_TRUE; 1079 1080 /* 1081 * Check the first block and determine if it's on a log device 1082 * which may have been removed or faulted prior to loading this 1083 * pool. If so, there's no point in checking the rest of the 1084 * log as its content should have already been synced to the 1085 * pool. 1086 */ 1087 spa_config_enter(os->os_spa, SCL_STATE, FTAG, RW_READER); 1088 vd = vdev_lookup_top(os->os_spa, DVA_GET_VDEV(&bp->blk_dva[0])); 1089 if (vd->vdev_islog && vdev_is_dead(vd)) 1090 valid = vdev_log_state_valid(vd); 1091 spa_config_exit(os->os_spa, SCL_STATE, FTAG); 1092 1093 if (!valid) 1094 return (0); 1095 1096 /* 1097 * Check whether the current uberblock is checkpointed (e.g. 1098 * we are rewinding) and whether the current header has been 1099 * claimed or not. If it hasn't then skip verifying it. We 1100 * do this because its ZIL blocks may be part of the pool's 1101 * state before the rewind, which is no longer valid. 1102 */ 1103 zil_header_t *zh = zil_header_in_syncing_context(zilog); 1104 if (zilog->zl_spa->spa_uberblock.ub_checkpoint_txg != 0 && 1105 zh->zh_claim_txg == 0) 1106 return (0); 1107 } 1108 1109 /* 1110 * Because tx == NULL, zil_claim_log_block() will not actually claim 1111 * any blocks, but just determine whether it is possible to do so. 1112 * In addition to checking the log chain, zil_claim_log_block() 1113 * will invoke zio_claim() with a done func of spa_claim_notify(), 1114 * which will update spa_max_claim_txg. See spa_load() for details. 1115 */ 1116 error = zil_parse(zilog, zil_claim_log_block, zil_claim_log_record, tx, 1117 zilog->zl_header->zh_claim_txg ? -1ULL : 1118 spa_min_claim_txg(os->os_spa), B_FALSE); 1119 1120 return ((error == ECKSUM || error == ENOENT) ? 0 : error); 1121 } 1122 1123 /* 1124 * When an itx is "skipped", this function is used to properly mark the 1125 * waiter as "done, and signal any thread(s) waiting on it. An itx can 1126 * be skipped (and not committed to an lwb) for a variety of reasons, 1127 * one of them being that the itx was committed via spa_sync(), prior to 1128 * it being committed to an lwb; this can happen if a thread calling 1129 * zil_commit() is racing with spa_sync(). 1130 */ 1131 static void 1132 zil_commit_waiter_skip(zil_commit_waiter_t *zcw) 1133 { 1134 mutex_enter(&zcw->zcw_lock); 1135 ASSERT3B(zcw->zcw_done, ==, B_FALSE); 1136 zcw->zcw_done = B_TRUE; 1137 cv_broadcast(&zcw->zcw_cv); 1138 mutex_exit(&zcw->zcw_lock); 1139 } 1140 1141 /* 1142 * This function is used when the given waiter is to be linked into an 1143 * lwb's "lwb_waiter" list; i.e. when the itx is committed to the lwb. 1144 * At this point, the waiter will no longer be referenced by the itx, 1145 * and instead, will be referenced by the lwb. 1146 */ 1147 static void 1148 zil_commit_waiter_link_lwb(zil_commit_waiter_t *zcw, lwb_t *lwb) 1149 { 1150 /* 1151 * The lwb_waiters field of the lwb is protected by the zilog's 1152 * zl_lock, thus it must be held when calling this function. 1153 */ 1154 ASSERT(MUTEX_HELD(&lwb->lwb_zilog->zl_lock)); 1155 1156 mutex_enter(&zcw->zcw_lock); 1157 ASSERT(!list_link_active(&zcw->zcw_node)); 1158 ASSERT3P(zcw->zcw_lwb, ==, NULL); 1159 ASSERT3P(lwb, !=, NULL); 1160 ASSERT(lwb->lwb_state == LWB_STATE_OPENED || 1161 lwb->lwb_state == LWB_STATE_ISSUED || 1162 lwb->lwb_state == LWB_STATE_WRITE_DONE); 1163 1164 list_insert_tail(&lwb->lwb_waiters, zcw); 1165 zcw->zcw_lwb = lwb; 1166 mutex_exit(&zcw->zcw_lock); 1167 } 1168 1169 /* 1170 * This function is used when zio_alloc_zil() fails to allocate a ZIL 1171 * block, and the given waiter must be linked to the "nolwb waiters" 1172 * list inside of zil_process_commit_list(). 1173 */ 1174 static void 1175 zil_commit_waiter_link_nolwb(zil_commit_waiter_t *zcw, list_t *nolwb) 1176 { 1177 mutex_enter(&zcw->zcw_lock); 1178 ASSERT(!list_link_active(&zcw->zcw_node)); 1179 ASSERT3P(zcw->zcw_lwb, ==, NULL); 1180 list_insert_tail(nolwb, zcw); 1181 mutex_exit(&zcw->zcw_lock); 1182 } 1183 1184 void 1185 zil_lwb_add_block(lwb_t *lwb, const blkptr_t *bp) 1186 { 1187 avl_tree_t *t = &lwb->lwb_vdev_tree; 1188 avl_index_t where; 1189 zil_vdev_node_t *zv, zvsearch; 1190 int ndvas = BP_GET_NDVAS(bp); 1191 int i; 1192 1193 if (zil_nocacheflush) 1194 return; 1195 1196 mutex_enter(&lwb->lwb_vdev_lock); 1197 for (i = 0; i < ndvas; i++) { 1198 zvsearch.zv_vdev = DVA_GET_VDEV(&bp->blk_dva[i]); 1199 if (avl_find(t, &zvsearch, &where) == NULL) { 1200 zv = kmem_alloc(sizeof (*zv), KM_SLEEP); 1201 zv->zv_vdev = zvsearch.zv_vdev; 1202 avl_insert(t, zv, where); 1203 } 1204 } 1205 mutex_exit(&lwb->lwb_vdev_lock); 1206 } 1207 1208 static void 1209 zil_lwb_flush_defer(lwb_t *lwb, lwb_t *nlwb) 1210 { 1211 avl_tree_t *src = &lwb->lwb_vdev_tree; 1212 avl_tree_t *dst = &nlwb->lwb_vdev_tree; 1213 void *cookie = NULL; 1214 zil_vdev_node_t *zv; 1215 1216 ASSERT3S(lwb->lwb_state, ==, LWB_STATE_WRITE_DONE); 1217 ASSERT3S(nlwb->lwb_state, !=, LWB_STATE_WRITE_DONE); 1218 ASSERT3S(nlwb->lwb_state, !=, LWB_STATE_FLUSH_DONE); 1219 1220 /* 1221 * While 'lwb' is at a point in its lifetime where lwb_vdev_tree does 1222 * not need the protection of lwb_vdev_lock (it will only be modified 1223 * while holding zilog->zl_lock) as its writes and those of its 1224 * children have all completed. The younger 'nlwb' may be waiting on 1225 * future writes to additional vdevs. 1226 */ 1227 mutex_enter(&nlwb->lwb_vdev_lock); 1228 /* 1229 * Tear down the 'lwb' vdev tree, ensuring that entries which do not 1230 * exist in 'nlwb' are moved to it, freeing any would-be duplicates. 1231 */ 1232 while ((zv = avl_destroy_nodes(src, &cookie)) != NULL) { 1233 avl_index_t where; 1234 1235 if (avl_find(dst, zv, &where) == NULL) { 1236 avl_insert(dst, zv, where); 1237 } else { 1238 kmem_free(zv, sizeof (*zv)); 1239 } 1240 } 1241 mutex_exit(&nlwb->lwb_vdev_lock); 1242 } 1243 1244 void 1245 zil_lwb_add_txg(lwb_t *lwb, uint64_t txg) 1246 { 1247 lwb->lwb_max_txg = MAX(lwb->lwb_max_txg, txg); 1248 } 1249 1250 /* 1251 * This function is a called after all vdevs associated with a given lwb 1252 * write have completed their DKIOCFLUSHWRITECACHE command; or as soon 1253 * as the lwb write completes, if "zil_nocacheflush" is set. Further, 1254 * all "previous" lwb's will have completed before this function is 1255 * called; i.e. this function is called for all previous lwbs before 1256 * it's called for "this" lwb (enforced via zio the dependencies 1257 * configured in zil_lwb_set_zio_dependency()). 1258 * 1259 * The intention is for this function to be called as soon as the 1260 * contents of an lwb are considered "stable" on disk, and will survive 1261 * any sudden loss of power. At this point, any threads waiting for the 1262 * lwb to reach this state are signalled, and the "waiter" structures 1263 * are marked "done". 1264 */ 1265 static void 1266 zil_lwb_flush_vdevs_done(zio_t *zio) 1267 { 1268 lwb_t *lwb = zio->io_private; 1269 zilog_t *zilog = lwb->lwb_zilog; 1270 zil_commit_waiter_t *zcw; 1271 itx_t *itx; 1272 uint64_t txg; 1273 1274 spa_config_exit(zilog->zl_spa, SCL_STATE, lwb); 1275 1276 zio_buf_free(lwb->lwb_buf, lwb->lwb_sz); 1277 1278 mutex_enter(&zilog->zl_lock); 1279 1280 /* 1281 * If we have had an allocation failure and the txg is 1282 * waiting to sync then we want zil_sync() to remove the lwb so 1283 * that it's not picked up as the next new one in 1284 * zil_process_commit_list(). zil_sync() will only remove the 1285 * lwb if lwb_buf is null. 1286 */ 1287 lwb->lwb_buf = NULL; 1288 1289 ASSERT3U(lwb->lwb_issued_timestamp, >, 0); 1290 zilog->zl_last_lwb_latency = gethrtime() - lwb->lwb_issued_timestamp; 1291 1292 lwb->lwb_root_zio = NULL; 1293 1294 ASSERT3S(lwb->lwb_state, ==, LWB_STATE_WRITE_DONE); 1295 lwb->lwb_state = LWB_STATE_FLUSH_DONE; 1296 1297 if (zilog->zl_last_lwb_opened == lwb) { 1298 /* 1299 * Remember the highest committed log sequence number 1300 * for ztest. We only update this value when all the log 1301 * writes succeeded, because ztest wants to ASSERT that 1302 * it got the whole log chain. 1303 */ 1304 zilog->zl_commit_lr_seq = zilog->zl_lr_seq; 1305 } 1306 1307 while ((itx = list_head(&lwb->lwb_itxs)) != NULL) { 1308 list_remove(&lwb->lwb_itxs, itx); 1309 zil_itx_destroy(itx); 1310 } 1311 1312 while ((zcw = list_head(&lwb->lwb_waiters)) != NULL) { 1313 mutex_enter(&zcw->zcw_lock); 1314 1315 ASSERT(list_link_active(&zcw->zcw_node)); 1316 list_remove(&lwb->lwb_waiters, zcw); 1317 1318 ASSERT3P(zcw->zcw_lwb, ==, lwb); 1319 zcw->zcw_lwb = NULL; 1320 /* 1321 * We expect any ZIO errors from child ZIOs to have been 1322 * propagated "up" to this specific LWB's root ZIO, in 1323 * order for this error handling to work correctly. This 1324 * includes ZIO errors from either this LWB's write or 1325 * flush, as well as any errors from other dependent LWBs 1326 * (e.g. a root LWB ZIO that might be a child of this LWB). 1327 * 1328 * With that said, it's important to note that LWB flush 1329 * errors are not propagated up to the LWB root ZIO. 1330 * This is incorrect behavior, and results in VDEV flush 1331 * errors not being handled correctly here. See the 1332 * comment above the call to "zio_flush" for details. 1333 */ 1334 1335 zcw->zcw_zio_error = zio->io_error; 1336 1337 ASSERT3B(zcw->zcw_done, ==, B_FALSE); 1338 zcw->zcw_done = B_TRUE; 1339 cv_broadcast(&zcw->zcw_cv); 1340 1341 mutex_exit(&zcw->zcw_lock); 1342 } 1343 1344 mutex_exit(&zilog->zl_lock); 1345 1346 mutex_enter(&zilog->zl_lwb_io_lock); 1347 txg = lwb->lwb_issued_txg; 1348 ASSERT3U(zilog->zl_lwb_inflight[txg & TXG_MASK], >, 0); 1349 zilog->zl_lwb_inflight[txg & TXG_MASK]--; 1350 if (zilog->zl_lwb_inflight[txg & TXG_MASK] == 0) 1351 cv_broadcast(&zilog->zl_lwb_io_cv); 1352 mutex_exit(&zilog->zl_lwb_io_lock); 1353 } 1354 1355 /* 1356 * Wait for the completion of all issued write/flush of that txg provided. 1357 * It guarantees zil_lwb_flush_vdevs_done() is called and returned. 1358 */ 1359 static void 1360 zil_lwb_flush_wait_all(zilog_t *zilog, uint64_t txg) 1361 { 1362 ASSERT3U(txg, ==, spa_syncing_txg(zilog->zl_spa)); 1363 1364 mutex_enter(&zilog->zl_lwb_io_lock); 1365 while (zilog->zl_lwb_inflight[txg & TXG_MASK] > 0) 1366 cv_wait(&zilog->zl_lwb_io_cv, &zilog->zl_lwb_io_lock); 1367 mutex_exit(&zilog->zl_lwb_io_lock); 1368 1369 #ifdef ZFS_DEBUG 1370 mutex_enter(&zilog->zl_lock); 1371 mutex_enter(&zilog->zl_lwb_io_lock); 1372 lwb_t *lwb = list_head(&zilog->zl_lwb_list); 1373 while (lwb != NULL && lwb->lwb_max_txg <= txg) { 1374 if (lwb->lwb_issued_txg <= txg) { 1375 ASSERT(lwb->lwb_state != LWB_STATE_ISSUED); 1376 ASSERT(lwb->lwb_state != LWB_STATE_WRITE_DONE); 1377 IMPLY(lwb->lwb_issued_txg > 0, 1378 lwb->lwb_state == LWB_STATE_FLUSH_DONE); 1379 } 1380 IMPLY(lwb->lwb_state == LWB_STATE_FLUSH_DONE, 1381 lwb->lwb_buf == NULL); 1382 lwb = list_next(&zilog->zl_lwb_list, lwb); 1383 } 1384 mutex_exit(&zilog->zl_lwb_io_lock); 1385 mutex_exit(&zilog->zl_lock); 1386 #endif 1387 } 1388 1389 /* 1390 * This is called when an lwb's write zio completes. The callback's 1391 * purpose is to issue the DKIOCFLUSHWRITECACHE commands for the vdevs 1392 * in the lwb's lwb_vdev_tree. The tree will contain the vdevs involved 1393 * in writing out this specific lwb's data, and in the case that cache 1394 * flushes have been deferred, vdevs involved in writing the data for 1395 * previous lwbs. The writes corresponding to all the vdevs in the 1396 * lwb_vdev_tree will have completed by the time this is called, due to 1397 * the zio dependencies configured in zil_lwb_set_zio_dependency(), 1398 * which takes deferred flushes into account. The lwb will be "done" 1399 * once zil_lwb_flush_vdevs_done() is called, which occurs in the zio 1400 * completion callback for the lwb's root zio. 1401 */ 1402 static void 1403 zil_lwb_write_done(zio_t *zio) 1404 { 1405 lwb_t *lwb = zio->io_private; 1406 spa_t *spa = zio->io_spa; 1407 zilog_t *zilog = lwb->lwb_zilog; 1408 avl_tree_t *t = &lwb->lwb_vdev_tree; 1409 void *cookie = NULL; 1410 zil_vdev_node_t *zv; 1411 lwb_t *nlwb; 1412 1413 ASSERT3S(spa_config_held(spa, SCL_STATE, RW_READER), !=, 0); 1414 1415 ASSERT(BP_GET_COMPRESS(zio->io_bp) == ZIO_COMPRESS_OFF); 1416 ASSERT(BP_GET_TYPE(zio->io_bp) == DMU_OT_INTENT_LOG); 1417 ASSERT(BP_GET_LEVEL(zio->io_bp) == 0); 1418 ASSERT(BP_GET_BYTEORDER(zio->io_bp) == ZFS_HOST_BYTEORDER); 1419 ASSERT(!BP_IS_GANG(zio->io_bp)); 1420 ASSERT(!BP_IS_HOLE(zio->io_bp)); 1421 ASSERT(BP_GET_FILL(zio->io_bp) == 0); 1422 1423 abd_free(zio->io_abd); 1424 1425 mutex_enter(&zilog->zl_lock); 1426 ASSERT3S(lwb->lwb_state, ==, LWB_STATE_ISSUED); 1427 lwb->lwb_state = LWB_STATE_WRITE_DONE; 1428 lwb->lwb_write_zio = NULL; 1429 lwb->lwb_fastwrite = FALSE; 1430 nlwb = list_next(&zilog->zl_lwb_list, lwb); 1431 mutex_exit(&zilog->zl_lock); 1432 1433 if (avl_numnodes(t) == 0) 1434 return; 1435 1436 /* 1437 * If there was an IO error, we're not going to call zio_flush() 1438 * on these vdevs, so we simply empty the tree and free the 1439 * nodes. We avoid calling zio_flush() since there isn't any 1440 * good reason for doing so, after the lwb block failed to be 1441 * written out. 1442 * 1443 * Additionally, we don't perform any further error handling at 1444 * this point (e.g. setting "zcw_zio_error" appropriately), as 1445 * we expect that to occur in "zil_lwb_flush_vdevs_done" (thus, 1446 * we expect any error seen here, to have been propagated to 1447 * that function). 1448 */ 1449 if (zio->io_error != 0) { 1450 while ((zv = avl_destroy_nodes(t, &cookie)) != NULL) 1451 kmem_free(zv, sizeof (*zv)); 1452 return; 1453 } 1454 1455 /* 1456 * If this lwb does not have any threads waiting for it to 1457 * complete, we want to defer issuing the DKIOCFLUSHWRITECACHE 1458 * command to the vdevs written to by "this" lwb, and instead 1459 * rely on the "next" lwb to handle the DKIOCFLUSHWRITECACHE 1460 * command for those vdevs. Thus, we merge the vdev tree of 1461 * "this" lwb with the vdev tree of the "next" lwb in the list, 1462 * and assume the "next" lwb will handle flushing the vdevs (or 1463 * deferring the flush(s) again). 1464 * 1465 * This is a useful performance optimization, especially for 1466 * workloads with lots of async write activity and few sync 1467 * write and/or fsync activity, as it has the potential to 1468 * coalesce multiple flush commands to a vdev into one. 1469 */ 1470 if (list_head(&lwb->lwb_waiters) == NULL && nlwb != NULL) { 1471 zil_lwb_flush_defer(lwb, nlwb); 1472 ASSERT(avl_is_empty(&lwb->lwb_vdev_tree)); 1473 return; 1474 } 1475 1476 while ((zv = avl_destroy_nodes(t, &cookie)) != NULL) { 1477 vdev_t *vd = vdev_lookup_top(spa, zv->zv_vdev); 1478 if (vd != NULL) { 1479 /* 1480 * The "ZIO_FLAG_DONT_PROPAGATE" is currently 1481 * always used within "zio_flush". This means, 1482 * any errors when flushing the vdev(s), will 1483 * (unfortunately) not be handled correctly, 1484 * since these "zio_flush" errors will not be 1485 * propagated up to "zil_lwb_flush_vdevs_done". 1486 */ 1487 zio_flush(lwb->lwb_root_zio, vd); 1488 } 1489 kmem_free(zv, sizeof (*zv)); 1490 } 1491 } 1492 1493 static void 1494 zil_lwb_set_zio_dependency(zilog_t *zilog, lwb_t *lwb) 1495 { 1496 lwb_t *last_lwb_opened = zilog->zl_last_lwb_opened; 1497 1498 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 1499 ASSERT(MUTEX_HELD(&zilog->zl_lock)); 1500 1501 /* 1502 * The zilog's "zl_last_lwb_opened" field is used to build the 1503 * lwb/zio dependency chain, which is used to preserve the 1504 * ordering of lwb completions that is required by the semantics 1505 * of the ZIL. Each new lwb zio becomes a parent of the 1506 * "previous" lwb zio, such that the new lwb's zio cannot 1507 * complete until the "previous" lwb's zio completes. 1508 * 1509 * This is required by the semantics of zil_commit(); the commit 1510 * waiters attached to the lwbs will be woken in the lwb zio's 1511 * completion callback, so this zio dependency graph ensures the 1512 * waiters are woken in the correct order (the same order the 1513 * lwbs were created). 1514 */ 1515 if (last_lwb_opened != NULL && 1516 last_lwb_opened->lwb_state != LWB_STATE_FLUSH_DONE) { 1517 ASSERT(last_lwb_opened->lwb_state == LWB_STATE_OPENED || 1518 last_lwb_opened->lwb_state == LWB_STATE_ISSUED || 1519 last_lwb_opened->lwb_state == LWB_STATE_WRITE_DONE); 1520 1521 ASSERT3P(last_lwb_opened->lwb_root_zio, !=, NULL); 1522 zio_add_child(lwb->lwb_root_zio, 1523 last_lwb_opened->lwb_root_zio); 1524 1525 /* 1526 * If the previous lwb's write hasn't already completed, 1527 * we also want to order the completion of the lwb write 1528 * zios (above, we only order the completion of the lwb 1529 * root zios). This is required because of how we can 1530 * defer the DKIOCFLUSHWRITECACHE commands for each lwb. 1531 * 1532 * When the DKIOCFLUSHWRITECACHE commands are deferred, 1533 * the previous lwb will rely on this lwb to flush the 1534 * vdevs written to by that previous lwb. Thus, we need 1535 * to ensure this lwb doesn't issue the flush until 1536 * after the previous lwb's write completes. We ensure 1537 * this ordering by setting the zio parent/child 1538 * relationship here. 1539 * 1540 * Without this relationship on the lwb's write zio, 1541 * it's possible for this lwb's write to complete prior 1542 * to the previous lwb's write completing; and thus, the 1543 * vdevs for the previous lwb would be flushed prior to 1544 * that lwb's data being written to those vdevs (the 1545 * vdevs are flushed in the lwb write zio's completion 1546 * handler, zil_lwb_write_done()). 1547 */ 1548 if (last_lwb_opened->lwb_state != LWB_STATE_WRITE_DONE) { 1549 ASSERT(last_lwb_opened->lwb_state == LWB_STATE_OPENED || 1550 last_lwb_opened->lwb_state == LWB_STATE_ISSUED); 1551 1552 ASSERT3P(last_lwb_opened->lwb_write_zio, !=, NULL); 1553 zio_add_child(lwb->lwb_write_zio, 1554 last_lwb_opened->lwb_write_zio); 1555 } 1556 } 1557 } 1558 1559 1560 /* 1561 * This function's purpose is to "open" an lwb such that it is ready to 1562 * accept new itxs being committed to it. To do this, the lwb's zio 1563 * structures are created, and linked to the lwb. This function is 1564 * idempotent; if the passed in lwb has already been opened, this 1565 * function is essentially a no-op. 1566 */ 1567 static void 1568 zil_lwb_write_open(zilog_t *zilog, lwb_t *lwb) 1569 { 1570 zbookmark_phys_t zb; 1571 zio_priority_t prio; 1572 1573 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 1574 ASSERT3P(lwb, !=, NULL); 1575 EQUIV(lwb->lwb_root_zio == NULL, lwb->lwb_state == LWB_STATE_CLOSED); 1576 EQUIV(lwb->lwb_root_zio != NULL, lwb->lwb_state == LWB_STATE_OPENED); 1577 1578 SET_BOOKMARK(&zb, lwb->lwb_blk.blk_cksum.zc_word[ZIL_ZC_OBJSET], 1579 ZB_ZIL_OBJECT, ZB_ZIL_LEVEL, 1580 lwb->lwb_blk.blk_cksum.zc_word[ZIL_ZC_SEQ]); 1581 1582 /* Lock so zil_sync() doesn't fastwrite_unmark after zio is created */ 1583 mutex_enter(&zilog->zl_lock); 1584 if (lwb->lwb_root_zio == NULL) { 1585 abd_t *lwb_abd = abd_get_from_buf(lwb->lwb_buf, 1586 BP_GET_LSIZE(&lwb->lwb_blk)); 1587 1588 if (!lwb->lwb_fastwrite) { 1589 metaslab_fastwrite_mark(zilog->zl_spa, &lwb->lwb_blk); 1590 lwb->lwb_fastwrite = 1; 1591 } 1592 1593 if (!lwb->lwb_slog || zilog->zl_cur_used <= zil_slog_bulk) 1594 prio = ZIO_PRIORITY_SYNC_WRITE; 1595 else 1596 prio = ZIO_PRIORITY_ASYNC_WRITE; 1597 1598 lwb->lwb_root_zio = zio_root(zilog->zl_spa, 1599 zil_lwb_flush_vdevs_done, lwb, ZIO_FLAG_CANFAIL); 1600 ASSERT3P(lwb->lwb_root_zio, !=, NULL); 1601 1602 lwb->lwb_write_zio = zio_rewrite(lwb->lwb_root_zio, 1603 zilog->zl_spa, 0, &lwb->lwb_blk, lwb_abd, 1604 BP_GET_LSIZE(&lwb->lwb_blk), zil_lwb_write_done, lwb, 1605 prio, ZIO_FLAG_CANFAIL | ZIO_FLAG_FASTWRITE, &zb); 1606 ASSERT3P(lwb->lwb_write_zio, !=, NULL); 1607 1608 lwb->lwb_state = LWB_STATE_OPENED; 1609 1610 zil_lwb_set_zio_dependency(zilog, lwb); 1611 zilog->zl_last_lwb_opened = lwb; 1612 } 1613 mutex_exit(&zilog->zl_lock); 1614 1615 ASSERT3P(lwb->lwb_root_zio, !=, NULL); 1616 ASSERT3P(lwb->lwb_write_zio, !=, NULL); 1617 ASSERT3S(lwb->lwb_state, ==, LWB_STATE_OPENED); 1618 } 1619 1620 /* 1621 * Define a limited set of intent log block sizes. 1622 * 1623 * These must be a multiple of 4KB. Note only the amount used (again 1624 * aligned to 4KB) actually gets written. However, we can't always just 1625 * allocate SPA_OLD_MAXBLOCKSIZE as the slog space could be exhausted. 1626 */ 1627 static const struct { 1628 uint64_t limit; 1629 uint64_t blksz; 1630 } zil_block_buckets[] = { 1631 { 4096, 4096 }, /* non TX_WRITE */ 1632 { 8192 + 4096, 8192 + 4096 }, /* database */ 1633 { 32768 + 4096, 32768 + 4096 }, /* NFS writes */ 1634 { 65536 + 4096, 65536 + 4096 }, /* 64KB writes */ 1635 { 131072, 131072 }, /* < 128KB writes */ 1636 { 131072 +4096, 65536 + 4096 }, /* 128KB writes */ 1637 { UINT64_MAX, SPA_OLD_MAXBLOCKSIZE}, /* > 128KB writes */ 1638 }; 1639 1640 /* 1641 * Maximum block size used by the ZIL. This is picked up when the ZIL is 1642 * initialized. Otherwise this should not be used directly; see 1643 * zl_max_block_size instead. 1644 */ 1645 static int zil_maxblocksize = SPA_OLD_MAXBLOCKSIZE; 1646 1647 /* 1648 * Start a log block write and advance to the next log block. 1649 * Calls are serialized. 1650 */ 1651 static lwb_t * 1652 zil_lwb_write_issue(zilog_t *zilog, lwb_t *lwb) 1653 { 1654 lwb_t *nlwb = NULL; 1655 zil_chain_t *zilc; 1656 spa_t *spa = zilog->zl_spa; 1657 blkptr_t *bp; 1658 dmu_tx_t *tx; 1659 uint64_t txg; 1660 uint64_t zil_blksz, wsz; 1661 int i, error; 1662 boolean_t slog; 1663 1664 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 1665 ASSERT3P(lwb->lwb_root_zio, !=, NULL); 1666 ASSERT3P(lwb->lwb_write_zio, !=, NULL); 1667 ASSERT3S(lwb->lwb_state, ==, LWB_STATE_OPENED); 1668 1669 if (BP_GET_CHECKSUM(&lwb->lwb_blk) == ZIO_CHECKSUM_ZILOG2) { 1670 zilc = (zil_chain_t *)lwb->lwb_buf; 1671 bp = &zilc->zc_next_blk; 1672 } else { 1673 zilc = (zil_chain_t *)(lwb->lwb_buf + lwb->lwb_sz); 1674 bp = &zilc->zc_next_blk; 1675 } 1676 1677 ASSERT(lwb->lwb_nused <= lwb->lwb_sz); 1678 1679 /* 1680 * Allocate the next block and save its address in this block 1681 * before writing it in order to establish the log chain. 1682 */ 1683 1684 tx = dmu_tx_create(zilog->zl_os); 1685 1686 /* 1687 * Since we are not going to create any new dirty data, and we 1688 * can even help with clearing the existing dirty data, we 1689 * should not be subject to the dirty data based delays. We 1690 * use TXG_NOTHROTTLE to bypass the delay mechanism. 1691 */ 1692 VERIFY0(dmu_tx_assign(tx, TXG_WAIT | TXG_NOTHROTTLE)); 1693 1694 dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx); 1695 txg = dmu_tx_get_txg(tx); 1696 1697 mutex_enter(&zilog->zl_lwb_io_lock); 1698 lwb->lwb_issued_txg = txg; 1699 zilog->zl_lwb_inflight[txg & TXG_MASK]++; 1700 zilog->zl_lwb_max_issued_txg = MAX(txg, zilog->zl_lwb_max_issued_txg); 1701 mutex_exit(&zilog->zl_lwb_io_lock); 1702 1703 /* 1704 * Log blocks are pre-allocated. Here we select the size of the next 1705 * block, based on size used in the last block. 1706 * - first find the smallest bucket that will fit the block from a 1707 * limited set of block sizes. This is because it's faster to write 1708 * blocks allocated from the same metaslab as they are adjacent or 1709 * close. 1710 * - next find the maximum from the new suggested size and an array of 1711 * previous sizes. This lessens a picket fence effect of wrongly 1712 * guessing the size if we have a stream of say 2k, 64k, 2k, 64k 1713 * requests. 1714 * 1715 * Note we only write what is used, but we can't just allocate 1716 * the maximum block size because we can exhaust the available 1717 * pool log space. 1718 */ 1719 zil_blksz = zilog->zl_cur_used + sizeof (zil_chain_t); 1720 for (i = 0; zil_blksz > zil_block_buckets[i].limit; i++) 1721 continue; 1722 zil_blksz = MIN(zil_block_buckets[i].blksz, zilog->zl_max_block_size); 1723 zilog->zl_prev_blks[zilog->zl_prev_rotor] = zil_blksz; 1724 for (i = 0; i < ZIL_PREV_BLKS; i++) 1725 zil_blksz = MAX(zil_blksz, zilog->zl_prev_blks[i]); 1726 zilog->zl_prev_rotor = (zilog->zl_prev_rotor + 1) & (ZIL_PREV_BLKS - 1); 1727 1728 BP_ZERO(bp); 1729 error = zio_alloc_zil(spa, zilog->zl_os, txg, bp, zil_blksz, &slog); 1730 if (slog) { 1731 ZIL_STAT_BUMP(zilog, zil_itx_metaslab_slog_count); 1732 ZIL_STAT_INCR(zilog, zil_itx_metaslab_slog_bytes, 1733 lwb->lwb_nused); 1734 } else { 1735 ZIL_STAT_BUMP(zilog, zil_itx_metaslab_normal_count); 1736 ZIL_STAT_INCR(zilog, zil_itx_metaslab_normal_bytes, 1737 lwb->lwb_nused); 1738 } 1739 if (error == 0) { 1740 ASSERT3U(bp->blk_birth, ==, txg); 1741 bp->blk_cksum = lwb->lwb_blk.blk_cksum; 1742 bp->blk_cksum.zc_word[ZIL_ZC_SEQ]++; 1743 1744 /* 1745 * Allocate a new log write block (lwb). 1746 */ 1747 nlwb = zil_alloc_lwb(zilog, bp, slog, txg, TRUE); 1748 } 1749 1750 if (BP_GET_CHECKSUM(&lwb->lwb_blk) == ZIO_CHECKSUM_ZILOG2) { 1751 /* For Slim ZIL only write what is used. */ 1752 wsz = P2ROUNDUP_TYPED(lwb->lwb_nused, ZIL_MIN_BLKSZ, uint64_t); 1753 ASSERT3U(wsz, <=, lwb->lwb_sz); 1754 zio_shrink(lwb->lwb_write_zio, wsz); 1755 1756 } else { 1757 wsz = lwb->lwb_sz; 1758 } 1759 1760 zilc->zc_pad = 0; 1761 zilc->zc_nused = lwb->lwb_nused; 1762 zilc->zc_eck.zec_cksum = lwb->lwb_blk.blk_cksum; 1763 1764 /* 1765 * clear unused data for security 1766 */ 1767 memset(lwb->lwb_buf + lwb->lwb_nused, 0, wsz - lwb->lwb_nused); 1768 1769 spa_config_enter(zilog->zl_spa, SCL_STATE, lwb, RW_READER); 1770 1771 zil_lwb_add_block(lwb, &lwb->lwb_blk); 1772 lwb->lwb_issued_timestamp = gethrtime(); 1773 lwb->lwb_state = LWB_STATE_ISSUED; 1774 1775 zio_nowait(lwb->lwb_root_zio); 1776 zio_nowait(lwb->lwb_write_zio); 1777 1778 dmu_tx_commit(tx); 1779 1780 /* 1781 * If there was an allocation failure then nlwb will be null which 1782 * forces a txg_wait_synced(). 1783 */ 1784 return (nlwb); 1785 } 1786 1787 /* 1788 * Maximum amount of write data that can be put into single log block. 1789 */ 1790 uint64_t 1791 zil_max_log_data(zilog_t *zilog) 1792 { 1793 return (zilog->zl_max_block_size - 1794 sizeof (zil_chain_t) - sizeof (lr_write_t)); 1795 } 1796 1797 /* 1798 * Maximum amount of log space we agree to waste to reduce number of 1799 * WR_NEED_COPY chunks to reduce zl_get_data() overhead (~12%). 1800 */ 1801 static inline uint64_t 1802 zil_max_waste_space(zilog_t *zilog) 1803 { 1804 return (zil_max_log_data(zilog) / 8); 1805 } 1806 1807 /* 1808 * Maximum amount of write data for WR_COPIED. For correctness, consumers 1809 * must fall back to WR_NEED_COPY if we can't fit the entire record into one 1810 * maximum sized log block, because each WR_COPIED record must fit in a 1811 * single log block. For space efficiency, we want to fit two records into a 1812 * max-sized log block. 1813 */ 1814 uint64_t 1815 zil_max_copied_data(zilog_t *zilog) 1816 { 1817 return ((zilog->zl_max_block_size - sizeof (zil_chain_t)) / 2 - 1818 sizeof (lr_write_t)); 1819 } 1820 1821 static lwb_t * 1822 zil_lwb_commit(zilog_t *zilog, itx_t *itx, lwb_t *lwb) 1823 { 1824 lr_t *lrcb, *lrc; 1825 lr_write_t *lrwb, *lrw; 1826 char *lr_buf; 1827 uint64_t dlen, dnow, dpad, lwb_sp, reclen, txg, max_log_data; 1828 1829 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 1830 ASSERT3P(lwb, !=, NULL); 1831 ASSERT3P(lwb->lwb_buf, !=, NULL); 1832 1833 zil_lwb_write_open(zilog, lwb); 1834 1835 lrc = &itx->itx_lr; 1836 lrw = (lr_write_t *)lrc; 1837 1838 /* 1839 * A commit itx doesn't represent any on-disk state; instead 1840 * it's simply used as a place holder on the commit list, and 1841 * provides a mechanism for attaching a "commit waiter" onto the 1842 * correct lwb (such that the waiter can be signalled upon 1843 * completion of that lwb). Thus, we don't process this itx's 1844 * log record if it's a commit itx (these itx's don't have log 1845 * records), and instead link the itx's waiter onto the lwb's 1846 * list of waiters. 1847 * 1848 * For more details, see the comment above zil_commit(). 1849 */ 1850 if (lrc->lrc_txtype == TX_COMMIT) { 1851 mutex_enter(&zilog->zl_lock); 1852 zil_commit_waiter_link_lwb(itx->itx_private, lwb); 1853 itx->itx_private = NULL; 1854 mutex_exit(&zilog->zl_lock); 1855 return (lwb); 1856 } 1857 1858 if (lrc->lrc_txtype == TX_WRITE && itx->itx_wr_state == WR_NEED_COPY) { 1859 dlen = P2ROUNDUP_TYPED( 1860 lrw->lr_length, sizeof (uint64_t), uint64_t); 1861 dpad = dlen - lrw->lr_length; 1862 } else { 1863 dlen = dpad = 0; 1864 } 1865 reclen = lrc->lrc_reclen; 1866 zilog->zl_cur_used += (reclen + dlen); 1867 txg = lrc->lrc_txg; 1868 1869 ASSERT3U(zilog->zl_cur_used, <, UINT64_MAX - (reclen + dlen)); 1870 1871 cont: 1872 /* 1873 * If this record won't fit in the current log block, start a new one. 1874 * For WR_NEED_COPY optimize layout for minimal number of chunks. 1875 */ 1876 lwb_sp = lwb->lwb_sz - lwb->lwb_nused; 1877 max_log_data = zil_max_log_data(zilog); 1878 if (reclen > lwb_sp || (reclen + dlen > lwb_sp && 1879 lwb_sp < zil_max_waste_space(zilog) && 1880 (dlen % max_log_data == 0 || 1881 lwb_sp < reclen + dlen % max_log_data))) { 1882 lwb = zil_lwb_write_issue(zilog, lwb); 1883 if (lwb == NULL) 1884 return (NULL); 1885 zil_lwb_write_open(zilog, lwb); 1886 ASSERT(LWB_EMPTY(lwb)); 1887 lwb_sp = lwb->lwb_sz - lwb->lwb_nused; 1888 1889 /* 1890 * There must be enough space in the new, empty log block to 1891 * hold reclen. For WR_COPIED, we need to fit the whole 1892 * record in one block, and reclen is the header size + the 1893 * data size. For WR_NEED_COPY, we can create multiple 1894 * records, splitting the data into multiple blocks, so we 1895 * only need to fit one word of data per block; in this case 1896 * reclen is just the header size (no data). 1897 */ 1898 ASSERT3U(reclen + MIN(dlen, sizeof (uint64_t)), <=, lwb_sp); 1899 } 1900 1901 dnow = MIN(dlen, lwb_sp - reclen); 1902 lr_buf = lwb->lwb_buf + lwb->lwb_nused; 1903 memcpy(lr_buf, lrc, reclen); 1904 lrcb = (lr_t *)lr_buf; /* Like lrc, but inside lwb. */ 1905 lrwb = (lr_write_t *)lrcb; /* Like lrw, but inside lwb. */ 1906 1907 ZIL_STAT_BUMP(zilog, zil_itx_count); 1908 1909 /* 1910 * If it's a write, fetch the data or get its blkptr as appropriate. 1911 */ 1912 if (lrc->lrc_txtype == TX_WRITE) { 1913 if (txg > spa_freeze_txg(zilog->zl_spa)) 1914 txg_wait_synced(zilog->zl_dmu_pool, txg); 1915 if (itx->itx_wr_state == WR_COPIED) { 1916 ZIL_STAT_BUMP(zilog, zil_itx_copied_count); 1917 ZIL_STAT_INCR(zilog, zil_itx_copied_bytes, 1918 lrw->lr_length); 1919 } else { 1920 char *dbuf; 1921 int error; 1922 1923 if (itx->itx_wr_state == WR_NEED_COPY) { 1924 dbuf = lr_buf + reclen; 1925 lrcb->lrc_reclen += dnow; 1926 if (lrwb->lr_length > dnow) 1927 lrwb->lr_length = dnow; 1928 lrw->lr_offset += dnow; 1929 lrw->lr_length -= dnow; 1930 ZIL_STAT_BUMP(zilog, zil_itx_needcopy_count); 1931 ZIL_STAT_INCR(zilog, zil_itx_needcopy_bytes, 1932 dnow); 1933 } else { 1934 ASSERT3S(itx->itx_wr_state, ==, WR_INDIRECT); 1935 dbuf = NULL; 1936 ZIL_STAT_BUMP(zilog, zil_itx_indirect_count); 1937 ZIL_STAT_INCR(zilog, zil_itx_indirect_bytes, 1938 lrw->lr_length); 1939 } 1940 1941 /* 1942 * We pass in the "lwb_write_zio" rather than 1943 * "lwb_root_zio" so that the "lwb_write_zio" 1944 * becomes the parent of any zio's created by 1945 * the "zl_get_data" callback. The vdevs are 1946 * flushed after the "lwb_write_zio" completes, 1947 * so we want to make sure that completion 1948 * callback waits for these additional zio's, 1949 * such that the vdevs used by those zio's will 1950 * be included in the lwb's vdev tree, and those 1951 * vdevs will be properly flushed. If we passed 1952 * in "lwb_root_zio" here, then these additional 1953 * vdevs may not be flushed; e.g. if these zio's 1954 * completed after "lwb_write_zio" completed. 1955 */ 1956 error = zilog->zl_get_data(itx->itx_private, 1957 itx->itx_gen, lrwb, dbuf, lwb, 1958 lwb->lwb_write_zio); 1959 if (dbuf != NULL && error == 0 && dnow == dlen) 1960 /* Zero any padding bytes in the last block. */ 1961 memset((char *)dbuf + lrwb->lr_length, 0, dpad); 1962 1963 if (error == EIO) { 1964 txg_wait_synced(zilog->zl_dmu_pool, txg); 1965 return (lwb); 1966 } 1967 if (error != 0) { 1968 ASSERT(error == ENOENT || error == EEXIST || 1969 error == EALREADY); 1970 return (lwb); 1971 } 1972 } 1973 } 1974 1975 /* 1976 * We're actually making an entry, so update lrc_seq to be the 1977 * log record sequence number. Note that this is generally not 1978 * equal to the itx sequence number because not all transactions 1979 * are synchronous, and sometimes spa_sync() gets there first. 1980 */ 1981 lrcb->lrc_seq = ++zilog->zl_lr_seq; 1982 lwb->lwb_nused += reclen + dnow; 1983 1984 zil_lwb_add_txg(lwb, txg); 1985 1986 ASSERT3U(lwb->lwb_nused, <=, lwb->lwb_sz); 1987 ASSERT0(P2PHASE(lwb->lwb_nused, sizeof (uint64_t))); 1988 1989 dlen -= dnow; 1990 if (dlen > 0) { 1991 zilog->zl_cur_used += reclen; 1992 goto cont; 1993 } 1994 1995 return (lwb); 1996 } 1997 1998 itx_t * 1999 zil_itx_create(uint64_t txtype, size_t olrsize) 2000 { 2001 size_t itxsize, lrsize; 2002 itx_t *itx; 2003 2004 lrsize = P2ROUNDUP_TYPED(olrsize, sizeof (uint64_t), size_t); 2005 itxsize = offsetof(itx_t, itx_lr) + lrsize; 2006 2007 itx = zio_data_buf_alloc(itxsize); 2008 itx->itx_lr.lrc_txtype = txtype; 2009 itx->itx_lr.lrc_reclen = lrsize; 2010 itx->itx_lr.lrc_seq = 0; /* defensive */ 2011 memset((char *)&itx->itx_lr + olrsize, 0, lrsize - olrsize); 2012 itx->itx_sync = B_TRUE; /* default is synchronous */ 2013 itx->itx_callback = NULL; 2014 itx->itx_callback_data = NULL; 2015 itx->itx_size = itxsize; 2016 2017 return (itx); 2018 } 2019 2020 void 2021 zil_itx_destroy(itx_t *itx) 2022 { 2023 IMPLY(itx->itx_lr.lrc_txtype == TX_COMMIT, itx->itx_callback == NULL); 2024 IMPLY(itx->itx_callback != NULL, itx->itx_lr.lrc_txtype != TX_COMMIT); 2025 2026 if (itx->itx_callback != NULL) 2027 itx->itx_callback(itx->itx_callback_data); 2028 2029 zio_data_buf_free(itx, itx->itx_size); 2030 } 2031 2032 /* 2033 * Free up the sync and async itxs. The itxs_t has already been detached 2034 * so no locks are needed. 2035 */ 2036 static void 2037 zil_itxg_clean(void *arg) 2038 { 2039 itx_t *itx; 2040 list_t *list; 2041 avl_tree_t *t; 2042 void *cookie; 2043 itxs_t *itxs = arg; 2044 itx_async_node_t *ian; 2045 2046 list = &itxs->i_sync_list; 2047 while ((itx = list_head(list)) != NULL) { 2048 /* 2049 * In the general case, commit itxs will not be found 2050 * here, as they'll be committed to an lwb via 2051 * zil_lwb_commit(), and free'd in that function. Having 2052 * said that, it is still possible for commit itxs to be 2053 * found here, due to the following race: 2054 * 2055 * - a thread calls zil_commit() which assigns the 2056 * commit itx to a per-txg i_sync_list 2057 * - zil_itxg_clean() is called (e.g. via spa_sync()) 2058 * while the waiter is still on the i_sync_list 2059 * 2060 * There's nothing to prevent syncing the txg while the 2061 * waiter is on the i_sync_list. This normally doesn't 2062 * happen because spa_sync() is slower than zil_commit(), 2063 * but if zil_commit() calls txg_wait_synced() (e.g. 2064 * because zil_create() or zil_commit_writer_stall() is 2065 * called) we will hit this case. 2066 */ 2067 if (itx->itx_lr.lrc_txtype == TX_COMMIT) 2068 zil_commit_waiter_skip(itx->itx_private); 2069 2070 list_remove(list, itx); 2071 zil_itx_destroy(itx); 2072 } 2073 2074 cookie = NULL; 2075 t = &itxs->i_async_tree; 2076 while ((ian = avl_destroy_nodes(t, &cookie)) != NULL) { 2077 list = &ian->ia_list; 2078 while ((itx = list_head(list)) != NULL) { 2079 list_remove(list, itx); 2080 /* commit itxs should never be on the async lists. */ 2081 ASSERT3U(itx->itx_lr.lrc_txtype, !=, TX_COMMIT); 2082 zil_itx_destroy(itx); 2083 } 2084 list_destroy(list); 2085 kmem_free(ian, sizeof (itx_async_node_t)); 2086 } 2087 avl_destroy(t); 2088 2089 kmem_free(itxs, sizeof (itxs_t)); 2090 } 2091 2092 static int 2093 zil_aitx_compare(const void *x1, const void *x2) 2094 { 2095 const uint64_t o1 = ((itx_async_node_t *)x1)->ia_foid; 2096 const uint64_t o2 = ((itx_async_node_t *)x2)->ia_foid; 2097 2098 return (TREE_CMP(o1, o2)); 2099 } 2100 2101 /* 2102 * Remove all async itx with the given oid. 2103 */ 2104 void 2105 zil_remove_async(zilog_t *zilog, uint64_t oid) 2106 { 2107 uint64_t otxg, txg; 2108 itx_async_node_t *ian; 2109 avl_tree_t *t; 2110 avl_index_t where; 2111 list_t clean_list; 2112 itx_t *itx; 2113 2114 ASSERT(oid != 0); 2115 list_create(&clean_list, sizeof (itx_t), offsetof(itx_t, itx_node)); 2116 2117 if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) /* ziltest support */ 2118 otxg = ZILTEST_TXG; 2119 else 2120 otxg = spa_last_synced_txg(zilog->zl_spa) + 1; 2121 2122 for (txg = otxg; txg < (otxg + TXG_CONCURRENT_STATES); txg++) { 2123 itxg_t *itxg = &zilog->zl_itxg[txg & TXG_MASK]; 2124 2125 mutex_enter(&itxg->itxg_lock); 2126 if (itxg->itxg_txg != txg) { 2127 mutex_exit(&itxg->itxg_lock); 2128 continue; 2129 } 2130 2131 /* 2132 * Locate the object node and append its list. 2133 */ 2134 t = &itxg->itxg_itxs->i_async_tree; 2135 ian = avl_find(t, &oid, &where); 2136 if (ian != NULL) 2137 list_move_tail(&clean_list, &ian->ia_list); 2138 mutex_exit(&itxg->itxg_lock); 2139 } 2140 while ((itx = list_head(&clean_list)) != NULL) { 2141 list_remove(&clean_list, itx); 2142 /* commit itxs should never be on the async lists. */ 2143 ASSERT3U(itx->itx_lr.lrc_txtype, !=, TX_COMMIT); 2144 zil_itx_destroy(itx); 2145 } 2146 list_destroy(&clean_list); 2147 } 2148 2149 void 2150 zil_itx_assign(zilog_t *zilog, itx_t *itx, dmu_tx_t *tx) 2151 { 2152 uint64_t txg; 2153 itxg_t *itxg; 2154 itxs_t *itxs, *clean = NULL; 2155 2156 /* 2157 * Ensure the data of a renamed file is committed before the rename. 2158 */ 2159 if ((itx->itx_lr.lrc_txtype & ~TX_CI) == TX_RENAME) 2160 zil_async_to_sync(zilog, itx->itx_oid); 2161 2162 if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) 2163 txg = ZILTEST_TXG; 2164 else 2165 txg = dmu_tx_get_txg(tx); 2166 2167 itxg = &zilog->zl_itxg[txg & TXG_MASK]; 2168 mutex_enter(&itxg->itxg_lock); 2169 itxs = itxg->itxg_itxs; 2170 if (itxg->itxg_txg != txg) { 2171 if (itxs != NULL) { 2172 /* 2173 * The zil_clean callback hasn't got around to cleaning 2174 * this itxg. Save the itxs for release below. 2175 * This should be rare. 2176 */ 2177 zfs_dbgmsg("zil_itx_assign: missed itx cleanup for " 2178 "txg %llu", (u_longlong_t)itxg->itxg_txg); 2179 clean = itxg->itxg_itxs; 2180 } 2181 itxg->itxg_txg = txg; 2182 itxs = itxg->itxg_itxs = kmem_zalloc(sizeof (itxs_t), 2183 KM_SLEEP); 2184 2185 list_create(&itxs->i_sync_list, sizeof (itx_t), 2186 offsetof(itx_t, itx_node)); 2187 avl_create(&itxs->i_async_tree, zil_aitx_compare, 2188 sizeof (itx_async_node_t), 2189 offsetof(itx_async_node_t, ia_node)); 2190 } 2191 if (itx->itx_sync) { 2192 list_insert_tail(&itxs->i_sync_list, itx); 2193 } else { 2194 avl_tree_t *t = &itxs->i_async_tree; 2195 uint64_t foid = 2196 LR_FOID_GET_OBJ(((lr_ooo_t *)&itx->itx_lr)->lr_foid); 2197 itx_async_node_t *ian; 2198 avl_index_t where; 2199 2200 ian = avl_find(t, &foid, &where); 2201 if (ian == NULL) { 2202 ian = kmem_alloc(sizeof (itx_async_node_t), 2203 KM_SLEEP); 2204 list_create(&ian->ia_list, sizeof (itx_t), 2205 offsetof(itx_t, itx_node)); 2206 ian->ia_foid = foid; 2207 avl_insert(t, ian, where); 2208 } 2209 list_insert_tail(&ian->ia_list, itx); 2210 } 2211 2212 itx->itx_lr.lrc_txg = dmu_tx_get_txg(tx); 2213 2214 /* 2215 * We don't want to dirty the ZIL using ZILTEST_TXG, because 2216 * zil_clean() will never be called using ZILTEST_TXG. Thus, we 2217 * need to be careful to always dirty the ZIL using the "real" 2218 * TXG (not itxg_txg) even when the SPA is frozen. 2219 */ 2220 zilog_dirty(zilog, dmu_tx_get_txg(tx)); 2221 mutex_exit(&itxg->itxg_lock); 2222 2223 /* Release the old itxs now we've dropped the lock */ 2224 if (clean != NULL) 2225 zil_itxg_clean(clean); 2226 } 2227 2228 /* 2229 * If there are any in-memory intent log transactions which have now been 2230 * synced then start up a taskq to free them. We should only do this after we 2231 * have written out the uberblocks (i.e. txg has been committed) so that 2232 * don't inadvertently clean out in-memory log records that would be required 2233 * by zil_commit(). 2234 */ 2235 void 2236 zil_clean(zilog_t *zilog, uint64_t synced_txg) 2237 { 2238 itxg_t *itxg = &zilog->zl_itxg[synced_txg & TXG_MASK]; 2239 itxs_t *clean_me; 2240 2241 ASSERT3U(synced_txg, <, ZILTEST_TXG); 2242 2243 mutex_enter(&itxg->itxg_lock); 2244 if (itxg->itxg_itxs == NULL || itxg->itxg_txg == ZILTEST_TXG) { 2245 mutex_exit(&itxg->itxg_lock); 2246 return; 2247 } 2248 ASSERT3U(itxg->itxg_txg, <=, synced_txg); 2249 ASSERT3U(itxg->itxg_txg, !=, 0); 2250 clean_me = itxg->itxg_itxs; 2251 itxg->itxg_itxs = NULL; 2252 itxg->itxg_txg = 0; 2253 mutex_exit(&itxg->itxg_lock); 2254 /* 2255 * Preferably start a task queue to free up the old itxs but 2256 * if taskq_dispatch can't allocate resources to do that then 2257 * free it in-line. This should be rare. Note, using TQ_SLEEP 2258 * created a bad performance problem. 2259 */ 2260 ASSERT3P(zilog->zl_dmu_pool, !=, NULL); 2261 ASSERT3P(zilog->zl_dmu_pool->dp_zil_clean_taskq, !=, NULL); 2262 taskqid_t id = taskq_dispatch(zilog->zl_dmu_pool->dp_zil_clean_taskq, 2263 zil_itxg_clean, clean_me, TQ_NOSLEEP); 2264 if (id == TASKQID_INVALID) 2265 zil_itxg_clean(clean_me); 2266 } 2267 2268 /* 2269 * This function will traverse the queue of itxs that need to be 2270 * committed, and move them onto the ZIL's zl_itx_commit_list. 2271 */ 2272 static void 2273 zil_get_commit_list(zilog_t *zilog) 2274 { 2275 uint64_t otxg, txg; 2276 list_t *commit_list = &zilog->zl_itx_commit_list; 2277 2278 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 2279 2280 if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) /* ziltest support */ 2281 otxg = ZILTEST_TXG; 2282 else 2283 otxg = spa_last_synced_txg(zilog->zl_spa) + 1; 2284 2285 /* 2286 * This is inherently racy, since there is nothing to prevent 2287 * the last synced txg from changing. That's okay since we'll 2288 * only commit things in the future. 2289 */ 2290 for (txg = otxg; txg < (otxg + TXG_CONCURRENT_STATES); txg++) { 2291 itxg_t *itxg = &zilog->zl_itxg[txg & TXG_MASK]; 2292 2293 mutex_enter(&itxg->itxg_lock); 2294 if (itxg->itxg_txg != txg) { 2295 mutex_exit(&itxg->itxg_lock); 2296 continue; 2297 } 2298 2299 /* 2300 * If we're adding itx records to the zl_itx_commit_list, 2301 * then the zil better be dirty in this "txg". We can assert 2302 * that here since we're holding the itxg_lock which will 2303 * prevent spa_sync from cleaning it. Once we add the itxs 2304 * to the zl_itx_commit_list we must commit it to disk even 2305 * if it's unnecessary (i.e. the txg was synced). 2306 */ 2307 ASSERT(zilog_is_dirty_in_txg(zilog, txg) || 2308 spa_freeze_txg(zilog->zl_spa) != UINT64_MAX); 2309 list_move_tail(commit_list, &itxg->itxg_itxs->i_sync_list); 2310 2311 mutex_exit(&itxg->itxg_lock); 2312 } 2313 } 2314 2315 /* 2316 * Move the async itxs for a specified object to commit into sync lists. 2317 */ 2318 void 2319 zil_async_to_sync(zilog_t *zilog, uint64_t foid) 2320 { 2321 uint64_t otxg, txg; 2322 itx_async_node_t *ian; 2323 avl_tree_t *t; 2324 avl_index_t where; 2325 2326 if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) /* ziltest support */ 2327 otxg = ZILTEST_TXG; 2328 else 2329 otxg = spa_last_synced_txg(zilog->zl_spa) + 1; 2330 2331 /* 2332 * This is inherently racy, since there is nothing to prevent 2333 * the last synced txg from changing. 2334 */ 2335 for (txg = otxg; txg < (otxg + TXG_CONCURRENT_STATES); txg++) { 2336 itxg_t *itxg = &zilog->zl_itxg[txg & TXG_MASK]; 2337 2338 mutex_enter(&itxg->itxg_lock); 2339 if (itxg->itxg_txg != txg) { 2340 mutex_exit(&itxg->itxg_lock); 2341 continue; 2342 } 2343 2344 /* 2345 * If a foid is specified then find that node and append its 2346 * list. Otherwise walk the tree appending all the lists 2347 * to the sync list. We add to the end rather than the 2348 * beginning to ensure the create has happened. 2349 */ 2350 t = &itxg->itxg_itxs->i_async_tree; 2351 if (foid != 0) { 2352 ian = avl_find(t, &foid, &where); 2353 if (ian != NULL) { 2354 list_move_tail(&itxg->itxg_itxs->i_sync_list, 2355 &ian->ia_list); 2356 } 2357 } else { 2358 void *cookie = NULL; 2359 2360 while ((ian = avl_destroy_nodes(t, &cookie)) != NULL) { 2361 list_move_tail(&itxg->itxg_itxs->i_sync_list, 2362 &ian->ia_list); 2363 list_destroy(&ian->ia_list); 2364 kmem_free(ian, sizeof (itx_async_node_t)); 2365 } 2366 } 2367 mutex_exit(&itxg->itxg_lock); 2368 } 2369 } 2370 2371 /* 2372 * This function will prune commit itxs that are at the head of the 2373 * commit list (it won't prune past the first non-commit itx), and 2374 * either: a) attach them to the last lwb that's still pending 2375 * completion, or b) skip them altogether. 2376 * 2377 * This is used as a performance optimization to prevent commit itxs 2378 * from generating new lwbs when it's unnecessary to do so. 2379 */ 2380 static void 2381 zil_prune_commit_list(zilog_t *zilog) 2382 { 2383 itx_t *itx; 2384 2385 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 2386 2387 while ((itx = list_head(&zilog->zl_itx_commit_list)) != NULL) { 2388 lr_t *lrc = &itx->itx_lr; 2389 if (lrc->lrc_txtype != TX_COMMIT) 2390 break; 2391 2392 mutex_enter(&zilog->zl_lock); 2393 2394 lwb_t *last_lwb = zilog->zl_last_lwb_opened; 2395 if (last_lwb == NULL || 2396 last_lwb->lwb_state == LWB_STATE_FLUSH_DONE) { 2397 /* 2398 * All of the itxs this waiter was waiting on 2399 * must have already completed (or there were 2400 * never any itx's for it to wait on), so it's 2401 * safe to skip this waiter and mark it done. 2402 */ 2403 zil_commit_waiter_skip(itx->itx_private); 2404 } else { 2405 zil_commit_waiter_link_lwb(itx->itx_private, last_lwb); 2406 itx->itx_private = NULL; 2407 } 2408 2409 mutex_exit(&zilog->zl_lock); 2410 2411 list_remove(&zilog->zl_itx_commit_list, itx); 2412 zil_itx_destroy(itx); 2413 } 2414 2415 IMPLY(itx != NULL, itx->itx_lr.lrc_txtype != TX_COMMIT); 2416 } 2417 2418 static void 2419 zil_commit_writer_stall(zilog_t *zilog) 2420 { 2421 /* 2422 * When zio_alloc_zil() fails to allocate the next lwb block on 2423 * disk, we must call txg_wait_synced() to ensure all of the 2424 * lwbs in the zilog's zl_lwb_list are synced and then freed (in 2425 * zil_sync()), such that any subsequent ZIL writer (i.e. a call 2426 * to zil_process_commit_list()) will have to call zil_create(), 2427 * and start a new ZIL chain. 2428 * 2429 * Since zil_alloc_zil() failed, the lwb that was previously 2430 * issued does not have a pointer to the "next" lwb on disk. 2431 * Thus, if another ZIL writer thread was to allocate the "next" 2432 * on-disk lwb, that block could be leaked in the event of a 2433 * crash (because the previous lwb on-disk would not point to 2434 * it). 2435 * 2436 * We must hold the zilog's zl_issuer_lock while we do this, to 2437 * ensure no new threads enter zil_process_commit_list() until 2438 * all lwb's in the zl_lwb_list have been synced and freed 2439 * (which is achieved via the txg_wait_synced() call). 2440 */ 2441 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 2442 txg_wait_synced(zilog->zl_dmu_pool, 0); 2443 ASSERT3P(list_tail(&zilog->zl_lwb_list), ==, NULL); 2444 } 2445 2446 /* 2447 * This function will traverse the commit list, creating new lwbs as 2448 * needed, and committing the itxs from the commit list to these newly 2449 * created lwbs. Additionally, as a new lwb is created, the previous 2450 * lwb will be issued to the zio layer to be written to disk. 2451 */ 2452 static void 2453 zil_process_commit_list(zilog_t *zilog) 2454 { 2455 spa_t *spa = zilog->zl_spa; 2456 list_t nolwb_itxs; 2457 list_t nolwb_waiters; 2458 lwb_t *lwb; 2459 itx_t *itx; 2460 2461 ASSERT(MUTEX_HELD(&zilog->zl_issuer_lock)); 2462 2463 /* 2464 * Return if there's nothing to commit before we dirty the fs by 2465 * calling zil_create(). 2466 */ 2467 if (list_head(&zilog->zl_itx_commit_list) == NULL) 2468 return; 2469 2470 list_create(&nolwb_itxs, sizeof (itx_t), offsetof(itx_t, itx_node)); 2471 list_create(&nolwb_waiters, sizeof (zil_commit_waiter_t), 2472 offsetof(zil_commit_waiter_t, zcw_node)); 2473 2474 lwb = list_tail(&zilog->zl_lwb_list); 2475 if (lwb == NULL) { 2476 lwb = zil_create(zilog); 2477 } else { 2478 /* 2479 * Activate SPA_FEATURE_ZILSAXATTR for the cases where ZIL will 2480 * have already been created (zl_lwb_list not empty). 2481 */ 2482 zil_commit_activate_saxattr_feature(zilog); 2483 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_ISSUED); 2484 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_WRITE_DONE); 2485 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_FLUSH_DONE); 2486 } 2487 2488 while ((itx = list_head(&zilog->zl_itx_commit_list)) != NULL) { 2489 lr_t *lrc = &itx->itx_lr; 2490 uint64_t txg = lrc->lrc_txg; 2491 2492 ASSERT3U(txg, !=, 0); 2493 2494 if (lrc->lrc_txtype == TX_COMMIT) { 2495 DTRACE_PROBE2(zil__process__commit__itx, 2496 zilog_t *, zilog, itx_t *, itx); 2497 } else { 2498 DTRACE_PROBE2(zil__process__normal__itx, 2499 zilog_t *, zilog, itx_t *, itx); 2500 } 2501 2502 list_remove(&zilog->zl_itx_commit_list, itx); 2503 2504 boolean_t synced = txg <= spa_last_synced_txg(spa); 2505 boolean_t frozen = txg > spa_freeze_txg(spa); 2506 2507 /* 2508 * If the txg of this itx has already been synced out, then 2509 * we don't need to commit this itx to an lwb. This is 2510 * because the data of this itx will have already been 2511 * written to the main pool. This is inherently racy, and 2512 * it's still ok to commit an itx whose txg has already 2513 * been synced; this will result in a write that's 2514 * unnecessary, but will do no harm. 2515 * 2516 * With that said, we always want to commit TX_COMMIT itxs 2517 * to an lwb, regardless of whether or not that itx's txg 2518 * has been synced out. We do this to ensure any OPENED lwb 2519 * will always have at least one zil_commit_waiter_t linked 2520 * to the lwb. 2521 * 2522 * As a counter-example, if we skipped TX_COMMIT itx's 2523 * whose txg had already been synced, the following 2524 * situation could occur if we happened to be racing with 2525 * spa_sync: 2526 * 2527 * 1. We commit a non-TX_COMMIT itx to an lwb, where the 2528 * itx's txg is 10 and the last synced txg is 9. 2529 * 2. spa_sync finishes syncing out txg 10. 2530 * 3. We move to the next itx in the list, it's a TX_COMMIT 2531 * whose txg is 10, so we skip it rather than committing 2532 * it to the lwb used in (1). 2533 * 2534 * If the itx that is skipped in (3) is the last TX_COMMIT 2535 * itx in the commit list, than it's possible for the lwb 2536 * used in (1) to remain in the OPENED state indefinitely. 2537 * 2538 * To prevent the above scenario from occurring, ensuring 2539 * that once an lwb is OPENED it will transition to ISSUED 2540 * and eventually DONE, we always commit TX_COMMIT itx's to 2541 * an lwb here, even if that itx's txg has already been 2542 * synced. 2543 * 2544 * Finally, if the pool is frozen, we _always_ commit the 2545 * itx. The point of freezing the pool is to prevent data 2546 * from being written to the main pool via spa_sync, and 2547 * instead rely solely on the ZIL to persistently store the 2548 * data; i.e. when the pool is frozen, the last synced txg 2549 * value can't be trusted. 2550 */ 2551 if (frozen || !synced || lrc->lrc_txtype == TX_COMMIT) { 2552 if (lwb != NULL) { 2553 lwb = zil_lwb_commit(zilog, itx, lwb); 2554 2555 if (lwb == NULL) 2556 list_insert_tail(&nolwb_itxs, itx); 2557 else 2558 list_insert_tail(&lwb->lwb_itxs, itx); 2559 } else { 2560 if (lrc->lrc_txtype == TX_COMMIT) { 2561 zil_commit_waiter_link_nolwb( 2562 itx->itx_private, &nolwb_waiters); 2563 } 2564 2565 list_insert_tail(&nolwb_itxs, itx); 2566 } 2567 } else { 2568 ASSERT3S(lrc->lrc_txtype, !=, TX_COMMIT); 2569 zil_itx_destroy(itx); 2570 } 2571 } 2572 2573 if (lwb == NULL) { 2574 /* 2575 * This indicates zio_alloc_zil() failed to allocate the 2576 * "next" lwb on-disk. When this happens, we must stall 2577 * the ZIL write pipeline; see the comment within 2578 * zil_commit_writer_stall() for more details. 2579 */ 2580 zil_commit_writer_stall(zilog); 2581 2582 /* 2583 * Additionally, we have to signal and mark the "nolwb" 2584 * waiters as "done" here, since without an lwb, we 2585 * can't do this via zil_lwb_flush_vdevs_done() like 2586 * normal. 2587 */ 2588 zil_commit_waiter_t *zcw; 2589 while ((zcw = list_head(&nolwb_waiters)) != NULL) { 2590 zil_commit_waiter_skip(zcw); 2591 list_remove(&nolwb_waiters, zcw); 2592 } 2593 2594 /* 2595 * And finally, we have to destroy the itx's that 2596 * couldn't be committed to an lwb; this will also call 2597 * the itx's callback if one exists for the itx. 2598 */ 2599 while ((itx = list_head(&nolwb_itxs)) != NULL) { 2600 list_remove(&nolwb_itxs, itx); 2601 zil_itx_destroy(itx); 2602 } 2603 } else { 2604 ASSERT(list_is_empty(&nolwb_waiters)); 2605 ASSERT3P(lwb, !=, NULL); 2606 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_ISSUED); 2607 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_WRITE_DONE); 2608 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_FLUSH_DONE); 2609 2610 /* 2611 * At this point, the ZIL block pointed at by the "lwb" 2612 * variable is in one of the following states: "closed" 2613 * or "open". 2614 * 2615 * If it's "closed", then no itxs have been committed to 2616 * it, so there's no point in issuing its zio (i.e. it's 2617 * "empty"). 2618 * 2619 * If it's "open", then it contains one or more itxs that 2620 * eventually need to be committed to stable storage. In 2621 * this case we intentionally do not issue the lwb's zio 2622 * to disk yet, and instead rely on one of the following 2623 * two mechanisms for issuing the zio: 2624 * 2625 * 1. Ideally, there will be more ZIL activity occurring 2626 * on the system, such that this function will be 2627 * immediately called again (not necessarily by the same 2628 * thread) and this lwb's zio will be issued via 2629 * zil_lwb_commit(). This way, the lwb is guaranteed to 2630 * be "full" when it is issued to disk, and we'll make 2631 * use of the lwb's size the best we can. 2632 * 2633 * 2. If there isn't sufficient ZIL activity occurring on 2634 * the system, such that this lwb's zio isn't issued via 2635 * zil_lwb_commit(), zil_commit_waiter() will issue the 2636 * lwb's zio. If this occurs, the lwb is not guaranteed 2637 * to be "full" by the time its zio is issued, and means 2638 * the size of the lwb was "too large" given the amount 2639 * of ZIL activity occurring on the system at that time. 2640 * 2641 * We do this for a couple of reasons: 2642 * 2643 * 1. To try and reduce the number of IOPs needed to 2644 * write the same number of itxs. If an lwb has space 2645 * available in its buffer for more itxs, and more itxs 2646 * will be committed relatively soon (relative to the 2647 * latency of performing a write), then it's beneficial 2648 * to wait for these "next" itxs. This way, more itxs 2649 * can be committed to stable storage with fewer writes. 2650 * 2651 * 2. To try and use the largest lwb block size that the 2652 * incoming rate of itxs can support. Again, this is to 2653 * try and pack as many itxs into as few lwbs as 2654 * possible, without significantly impacting the latency 2655 * of each individual itx. 2656 */ 2657 } 2658 } 2659 2660 /* 2661 * This function is responsible for ensuring the passed in commit waiter 2662 * (and associated commit itx) is committed to an lwb. If the waiter is 2663 * not already committed to an lwb, all itxs in the zilog's queue of 2664 * itxs will be processed. The assumption is the passed in waiter's 2665 * commit itx will found in the queue just like the other non-commit 2666 * itxs, such that when the entire queue is processed, the waiter will 2667 * have been committed to an lwb. 2668 * 2669 * The lwb associated with the passed in waiter is not guaranteed to 2670 * have been issued by the time this function completes. If the lwb is 2671 * not issued, we rely on future calls to zil_commit_writer() to issue 2672 * the lwb, or the timeout mechanism found in zil_commit_waiter(). 2673 */ 2674 static void 2675 zil_commit_writer(zilog_t *zilog, zil_commit_waiter_t *zcw) 2676 { 2677 ASSERT(!MUTEX_HELD(&zilog->zl_lock)); 2678 ASSERT(spa_writeable(zilog->zl_spa)); 2679 2680 mutex_enter(&zilog->zl_issuer_lock); 2681 2682 if (zcw->zcw_lwb != NULL || zcw->zcw_done) { 2683 /* 2684 * It's possible that, while we were waiting to acquire 2685 * the "zl_issuer_lock", another thread committed this 2686 * waiter to an lwb. If that occurs, we bail out early, 2687 * without processing any of the zilog's queue of itxs. 2688 * 2689 * On certain workloads and system configurations, the 2690 * "zl_issuer_lock" can become highly contended. In an 2691 * attempt to reduce this contention, we immediately drop 2692 * the lock if the waiter has already been processed. 2693 * 2694 * We've measured this optimization to reduce CPU spent 2695 * contending on this lock by up to 5%, using a system 2696 * with 32 CPUs, low latency storage (~50 usec writes), 2697 * and 1024 threads performing sync writes. 2698 */ 2699 goto out; 2700 } 2701 2702 ZIL_STAT_BUMP(zilog, zil_commit_writer_count); 2703 2704 zil_get_commit_list(zilog); 2705 zil_prune_commit_list(zilog); 2706 zil_process_commit_list(zilog); 2707 2708 out: 2709 mutex_exit(&zilog->zl_issuer_lock); 2710 } 2711 2712 static void 2713 zil_commit_waiter_timeout(zilog_t *zilog, zil_commit_waiter_t *zcw) 2714 { 2715 ASSERT(!MUTEX_HELD(&zilog->zl_issuer_lock)); 2716 ASSERT(MUTEX_HELD(&zcw->zcw_lock)); 2717 ASSERT3B(zcw->zcw_done, ==, B_FALSE); 2718 2719 lwb_t *lwb = zcw->zcw_lwb; 2720 ASSERT3P(lwb, !=, NULL); 2721 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_CLOSED); 2722 2723 /* 2724 * If the lwb has already been issued by another thread, we can 2725 * immediately return since there's no work to be done (the 2726 * point of this function is to issue the lwb). Additionally, we 2727 * do this prior to acquiring the zl_issuer_lock, to avoid 2728 * acquiring it when it's not necessary to do so. 2729 */ 2730 if (lwb->lwb_state == LWB_STATE_ISSUED || 2731 lwb->lwb_state == LWB_STATE_WRITE_DONE || 2732 lwb->lwb_state == LWB_STATE_FLUSH_DONE) 2733 return; 2734 2735 /* 2736 * In order to call zil_lwb_write_issue() we must hold the 2737 * zilog's "zl_issuer_lock". We can't simply acquire that lock, 2738 * since we're already holding the commit waiter's "zcw_lock", 2739 * and those two locks are acquired in the opposite order 2740 * elsewhere. 2741 */ 2742 mutex_exit(&zcw->zcw_lock); 2743 mutex_enter(&zilog->zl_issuer_lock); 2744 mutex_enter(&zcw->zcw_lock); 2745 2746 /* 2747 * Since we just dropped and re-acquired the commit waiter's 2748 * lock, we have to re-check to see if the waiter was marked 2749 * "done" during that process. If the waiter was marked "done", 2750 * the "lwb" pointer is no longer valid (it can be free'd after 2751 * the waiter is marked "done"), so without this check we could 2752 * wind up with a use-after-free error below. 2753 */ 2754 if (zcw->zcw_done) 2755 goto out; 2756 2757 ASSERT3P(lwb, ==, zcw->zcw_lwb); 2758 2759 /* 2760 * We've already checked this above, but since we hadn't acquired 2761 * the zilog's zl_issuer_lock, we have to perform this check a 2762 * second time while holding the lock. 2763 * 2764 * We don't need to hold the zl_lock since the lwb cannot transition 2765 * from OPENED to ISSUED while we hold the zl_issuer_lock. The lwb 2766 * _can_ transition from ISSUED to DONE, but it's OK to race with 2767 * that transition since we treat the lwb the same, whether it's in 2768 * the ISSUED or DONE states. 2769 * 2770 * The important thing, is we treat the lwb differently depending on 2771 * if it's ISSUED or OPENED, and block any other threads that might 2772 * attempt to issue this lwb. For that reason we hold the 2773 * zl_issuer_lock when checking the lwb_state; we must not call 2774 * zil_lwb_write_issue() if the lwb had already been issued. 2775 * 2776 * See the comment above the lwb_state_t structure definition for 2777 * more details on the lwb states, and locking requirements. 2778 */ 2779 if (lwb->lwb_state == LWB_STATE_ISSUED || 2780 lwb->lwb_state == LWB_STATE_WRITE_DONE || 2781 lwb->lwb_state == LWB_STATE_FLUSH_DONE) 2782 goto out; 2783 2784 ASSERT3S(lwb->lwb_state, ==, LWB_STATE_OPENED); 2785 2786 /* 2787 * As described in the comments above zil_commit_waiter() and 2788 * zil_process_commit_list(), we need to issue this lwb's zio 2789 * since we've reached the commit waiter's timeout and it still 2790 * hasn't been issued. 2791 */ 2792 lwb_t *nlwb = zil_lwb_write_issue(zilog, lwb); 2793 2794 IMPLY(nlwb != NULL, lwb->lwb_state != LWB_STATE_OPENED); 2795 2796 /* 2797 * Since the lwb's zio hadn't been issued by the time this thread 2798 * reached its timeout, we reset the zilog's "zl_cur_used" field 2799 * to influence the zil block size selection algorithm. 2800 * 2801 * By having to issue the lwb's zio here, it means the size of the 2802 * lwb was too large, given the incoming throughput of itxs. By 2803 * setting "zl_cur_used" to zero, we communicate this fact to the 2804 * block size selection algorithm, so it can take this information 2805 * into account, and potentially select a smaller size for the 2806 * next lwb block that is allocated. 2807 */ 2808 zilog->zl_cur_used = 0; 2809 2810 if (nlwb == NULL) { 2811 /* 2812 * When zil_lwb_write_issue() returns NULL, this 2813 * indicates zio_alloc_zil() failed to allocate the 2814 * "next" lwb on-disk. When this occurs, the ZIL write 2815 * pipeline must be stalled; see the comment within the 2816 * zil_commit_writer_stall() function for more details. 2817 * 2818 * We must drop the commit waiter's lock prior to 2819 * calling zil_commit_writer_stall() or else we can wind 2820 * up with the following deadlock: 2821 * 2822 * - This thread is waiting for the txg to sync while 2823 * holding the waiter's lock; txg_wait_synced() is 2824 * used within txg_commit_writer_stall(). 2825 * 2826 * - The txg can't sync because it is waiting for this 2827 * lwb's zio callback to call dmu_tx_commit(). 2828 * 2829 * - The lwb's zio callback can't call dmu_tx_commit() 2830 * because it's blocked trying to acquire the waiter's 2831 * lock, which occurs prior to calling dmu_tx_commit() 2832 */ 2833 mutex_exit(&zcw->zcw_lock); 2834 zil_commit_writer_stall(zilog); 2835 mutex_enter(&zcw->zcw_lock); 2836 } 2837 2838 out: 2839 mutex_exit(&zilog->zl_issuer_lock); 2840 ASSERT(MUTEX_HELD(&zcw->zcw_lock)); 2841 } 2842 2843 /* 2844 * This function is responsible for performing the following two tasks: 2845 * 2846 * 1. its primary responsibility is to block until the given "commit 2847 * waiter" is considered "done". 2848 * 2849 * 2. its secondary responsibility is to issue the zio for the lwb that 2850 * the given "commit waiter" is waiting on, if this function has 2851 * waited "long enough" and the lwb is still in the "open" state. 2852 * 2853 * Given a sufficient amount of itxs being generated and written using 2854 * the ZIL, the lwb's zio will be issued via the zil_lwb_commit() 2855 * function. If this does not occur, this secondary responsibility will 2856 * ensure the lwb is issued even if there is not other synchronous 2857 * activity on the system. 2858 * 2859 * For more details, see zil_process_commit_list(); more specifically, 2860 * the comment at the bottom of that function. 2861 */ 2862 static void 2863 zil_commit_waiter(zilog_t *zilog, zil_commit_waiter_t *zcw) 2864 { 2865 ASSERT(!MUTEX_HELD(&zilog->zl_lock)); 2866 ASSERT(!MUTEX_HELD(&zilog->zl_issuer_lock)); 2867 ASSERT(spa_writeable(zilog->zl_spa)); 2868 2869 mutex_enter(&zcw->zcw_lock); 2870 2871 /* 2872 * The timeout is scaled based on the lwb latency to avoid 2873 * significantly impacting the latency of each individual itx. 2874 * For more details, see the comment at the bottom of the 2875 * zil_process_commit_list() function. 2876 */ 2877 int pct = MAX(zfs_commit_timeout_pct, 1); 2878 hrtime_t sleep = (zilog->zl_last_lwb_latency * pct) / 100; 2879 hrtime_t wakeup = gethrtime() + sleep; 2880 boolean_t timedout = B_FALSE; 2881 2882 while (!zcw->zcw_done) { 2883 ASSERT(MUTEX_HELD(&zcw->zcw_lock)); 2884 2885 lwb_t *lwb = zcw->zcw_lwb; 2886 2887 /* 2888 * Usually, the waiter will have a non-NULL lwb field here, 2889 * but it's possible for it to be NULL as a result of 2890 * zil_commit() racing with spa_sync(). 2891 * 2892 * When zil_clean() is called, it's possible for the itxg 2893 * list (which may be cleaned via a taskq) to contain 2894 * commit itxs. When this occurs, the commit waiters linked 2895 * off of these commit itxs will not be committed to an 2896 * lwb. Additionally, these commit waiters will not be 2897 * marked done until zil_commit_waiter_skip() is called via 2898 * zil_itxg_clean(). 2899 * 2900 * Thus, it's possible for this commit waiter (i.e. the 2901 * "zcw" variable) to be found in this "in between" state; 2902 * where it's "zcw_lwb" field is NULL, and it hasn't yet 2903 * been skipped, so it's "zcw_done" field is still B_FALSE. 2904 */ 2905 IMPLY(lwb != NULL, lwb->lwb_state != LWB_STATE_CLOSED); 2906 2907 if (lwb != NULL && lwb->lwb_state == LWB_STATE_OPENED) { 2908 ASSERT3B(timedout, ==, B_FALSE); 2909 2910 /* 2911 * If the lwb hasn't been issued yet, then we 2912 * need to wait with a timeout, in case this 2913 * function needs to issue the lwb after the 2914 * timeout is reached; responsibility (2) from 2915 * the comment above this function. 2916 */ 2917 int rc = cv_timedwait_hires(&zcw->zcw_cv, 2918 &zcw->zcw_lock, wakeup, USEC2NSEC(1), 2919 CALLOUT_FLAG_ABSOLUTE); 2920 2921 if (rc != -1 || zcw->zcw_done) 2922 continue; 2923 2924 timedout = B_TRUE; 2925 zil_commit_waiter_timeout(zilog, zcw); 2926 2927 if (!zcw->zcw_done) { 2928 /* 2929 * If the commit waiter has already been 2930 * marked "done", it's possible for the 2931 * waiter's lwb structure to have already 2932 * been freed. Thus, we can only reliably 2933 * make these assertions if the waiter 2934 * isn't done. 2935 */ 2936 ASSERT3P(lwb, ==, zcw->zcw_lwb); 2937 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_OPENED); 2938 } 2939 } else { 2940 /* 2941 * If the lwb isn't open, then it must have already 2942 * been issued. In that case, there's no need to 2943 * use a timeout when waiting for the lwb to 2944 * complete. 2945 * 2946 * Additionally, if the lwb is NULL, the waiter 2947 * will soon be signaled and marked done via 2948 * zil_clean() and zil_itxg_clean(), so no timeout 2949 * is required. 2950 */ 2951 2952 IMPLY(lwb != NULL, 2953 lwb->lwb_state == LWB_STATE_ISSUED || 2954 lwb->lwb_state == LWB_STATE_WRITE_DONE || 2955 lwb->lwb_state == LWB_STATE_FLUSH_DONE); 2956 cv_wait(&zcw->zcw_cv, &zcw->zcw_lock); 2957 } 2958 } 2959 2960 mutex_exit(&zcw->zcw_lock); 2961 } 2962 2963 static zil_commit_waiter_t * 2964 zil_alloc_commit_waiter(void) 2965 { 2966 zil_commit_waiter_t *zcw = kmem_cache_alloc(zil_zcw_cache, KM_SLEEP); 2967 2968 cv_init(&zcw->zcw_cv, NULL, CV_DEFAULT, NULL); 2969 mutex_init(&zcw->zcw_lock, NULL, MUTEX_DEFAULT, NULL); 2970 list_link_init(&zcw->zcw_node); 2971 zcw->zcw_lwb = NULL; 2972 zcw->zcw_done = B_FALSE; 2973 zcw->zcw_zio_error = 0; 2974 2975 return (zcw); 2976 } 2977 2978 static void 2979 zil_free_commit_waiter(zil_commit_waiter_t *zcw) 2980 { 2981 ASSERT(!list_link_active(&zcw->zcw_node)); 2982 ASSERT3P(zcw->zcw_lwb, ==, NULL); 2983 ASSERT3B(zcw->zcw_done, ==, B_TRUE); 2984 mutex_destroy(&zcw->zcw_lock); 2985 cv_destroy(&zcw->zcw_cv); 2986 kmem_cache_free(zil_zcw_cache, zcw); 2987 } 2988 2989 /* 2990 * This function is used to create a TX_COMMIT itx and assign it. This 2991 * way, it will be linked into the ZIL's list of synchronous itxs, and 2992 * then later committed to an lwb (or skipped) when 2993 * zil_process_commit_list() is called. 2994 */ 2995 static void 2996 zil_commit_itx_assign(zilog_t *zilog, zil_commit_waiter_t *zcw) 2997 { 2998 dmu_tx_t *tx = dmu_tx_create(zilog->zl_os); 2999 VERIFY0(dmu_tx_assign(tx, TXG_WAIT)); 3000 3001 itx_t *itx = zil_itx_create(TX_COMMIT, sizeof (lr_t)); 3002 itx->itx_sync = B_TRUE; 3003 itx->itx_private = zcw; 3004 3005 zil_itx_assign(zilog, itx, tx); 3006 3007 dmu_tx_commit(tx); 3008 } 3009 3010 /* 3011 * Commit ZFS Intent Log transactions (itxs) to stable storage. 3012 * 3013 * When writing ZIL transactions to the on-disk representation of the 3014 * ZIL, the itxs are committed to a Log Write Block (lwb). Multiple 3015 * itxs can be committed to a single lwb. Once a lwb is written and 3016 * committed to stable storage (i.e. the lwb is written, and vdevs have 3017 * been flushed), each itx that was committed to that lwb is also 3018 * considered to be committed to stable storage. 3019 * 3020 * When an itx is committed to an lwb, the log record (lr_t) contained 3021 * by the itx is copied into the lwb's zio buffer, and once this buffer 3022 * is written to disk, it becomes an on-disk ZIL block. 3023 * 3024 * As itxs are generated, they're inserted into the ZIL's queue of 3025 * uncommitted itxs. The semantics of zil_commit() are such that it will 3026 * block until all itxs that were in the queue when it was called, are 3027 * committed to stable storage. 3028 * 3029 * If "foid" is zero, this means all "synchronous" and "asynchronous" 3030 * itxs, for all objects in the dataset, will be committed to stable 3031 * storage prior to zil_commit() returning. If "foid" is non-zero, all 3032 * "synchronous" itxs for all objects, but only "asynchronous" itxs 3033 * that correspond to the foid passed in, will be committed to stable 3034 * storage prior to zil_commit() returning. 3035 * 3036 * Generally speaking, when zil_commit() is called, the consumer doesn't 3037 * actually care about _all_ of the uncommitted itxs. Instead, they're 3038 * simply trying to waiting for a specific itx to be committed to disk, 3039 * but the interface(s) for interacting with the ZIL don't allow such 3040 * fine-grained communication. A better interface would allow a consumer 3041 * to create and assign an itx, and then pass a reference to this itx to 3042 * zil_commit(); such that zil_commit() would return as soon as that 3043 * specific itx was committed to disk (instead of waiting for _all_ 3044 * itxs to be committed). 3045 * 3046 * When a thread calls zil_commit() a special "commit itx" will be 3047 * generated, along with a corresponding "waiter" for this commit itx. 3048 * zil_commit() will wait on this waiter's CV, such that when the waiter 3049 * is marked done, and signaled, zil_commit() will return. 3050 * 3051 * This commit itx is inserted into the queue of uncommitted itxs. This 3052 * provides an easy mechanism for determining which itxs were in the 3053 * queue prior to zil_commit() having been called, and which itxs were 3054 * added after zil_commit() was called. 3055 * 3056 * The commit itx is special; it doesn't have any on-disk representation. 3057 * When a commit itx is "committed" to an lwb, the waiter associated 3058 * with it is linked onto the lwb's list of waiters. Then, when that lwb 3059 * completes, each waiter on the lwb's list is marked done and signaled 3060 * -- allowing the thread waiting on the waiter to return from zil_commit(). 3061 * 3062 * It's important to point out a few critical factors that allow us 3063 * to make use of the commit itxs, commit waiters, per-lwb lists of 3064 * commit waiters, and zio completion callbacks like we're doing: 3065 * 3066 * 1. The list of waiters for each lwb is traversed, and each commit 3067 * waiter is marked "done" and signaled, in the zio completion 3068 * callback of the lwb's zio[*]. 3069 * 3070 * * Actually, the waiters are signaled in the zio completion 3071 * callback of the root zio for the DKIOCFLUSHWRITECACHE commands 3072 * that are sent to the vdevs upon completion of the lwb zio. 3073 * 3074 * 2. When the itxs are inserted into the ZIL's queue of uncommitted 3075 * itxs, the order in which they are inserted is preserved[*]; as 3076 * itxs are added to the queue, they are added to the tail of 3077 * in-memory linked lists. 3078 * 3079 * When committing the itxs to lwbs (to be written to disk), they 3080 * are committed in the same order in which the itxs were added to 3081 * the uncommitted queue's linked list(s); i.e. the linked list of 3082 * itxs to commit is traversed from head to tail, and each itx is 3083 * committed to an lwb in that order. 3084 * 3085 * * To clarify: 3086 * 3087 * - the order of "sync" itxs is preserved w.r.t. other 3088 * "sync" itxs, regardless of the corresponding objects. 3089 * - the order of "async" itxs is preserved w.r.t. other 3090 * "async" itxs corresponding to the same object. 3091 * - the order of "async" itxs is *not* preserved w.r.t. other 3092 * "async" itxs corresponding to different objects. 3093 * - the order of "sync" itxs w.r.t. "async" itxs (or vice 3094 * versa) is *not* preserved, even for itxs that correspond 3095 * to the same object. 3096 * 3097 * For more details, see: zil_itx_assign(), zil_async_to_sync(), 3098 * zil_get_commit_list(), and zil_process_commit_list(). 3099 * 3100 * 3. The lwbs represent a linked list of blocks on disk. Thus, any 3101 * lwb cannot be considered committed to stable storage, until its 3102 * "previous" lwb is also committed to stable storage. This fact, 3103 * coupled with the fact described above, means that itxs are 3104 * committed in (roughly) the order in which they were generated. 3105 * This is essential because itxs are dependent on prior itxs. 3106 * Thus, we *must not* deem an itx as being committed to stable 3107 * storage, until *all* prior itxs have also been committed to 3108 * stable storage. 3109 * 3110 * To enforce this ordering of lwb zio's, while still leveraging as 3111 * much of the underlying storage performance as possible, we rely 3112 * on two fundamental concepts: 3113 * 3114 * 1. The creation and issuance of lwb zio's is protected by 3115 * the zilog's "zl_issuer_lock", which ensures only a single 3116 * thread is creating and/or issuing lwb's at a time 3117 * 2. The "previous" lwb is a child of the "current" lwb 3118 * (leveraging the zio parent-child dependency graph) 3119 * 3120 * By relying on this parent-child zio relationship, we can have 3121 * many lwb zio's concurrently issued to the underlying storage, 3122 * but the order in which they complete will be the same order in 3123 * which they were created. 3124 */ 3125 void 3126 zil_commit(zilog_t *zilog, uint64_t foid) 3127 { 3128 /* 3129 * We should never attempt to call zil_commit on a snapshot for 3130 * a couple of reasons: 3131 * 3132 * 1. A snapshot may never be modified, thus it cannot have any 3133 * in-flight itxs that would have modified the dataset. 3134 * 3135 * 2. By design, when zil_commit() is called, a commit itx will 3136 * be assigned to this zilog; as a result, the zilog will be 3137 * dirtied. We must not dirty the zilog of a snapshot; there's 3138 * checks in the code that enforce this invariant, and will 3139 * cause a panic if it's not upheld. 3140 */ 3141 ASSERT3B(dmu_objset_is_snapshot(zilog->zl_os), ==, B_FALSE); 3142 3143 if (zilog->zl_sync == ZFS_SYNC_DISABLED) 3144 return; 3145 3146 if (!spa_writeable(zilog->zl_spa)) { 3147 /* 3148 * If the SPA is not writable, there should never be any 3149 * pending itxs waiting to be committed to disk. If that 3150 * weren't true, we'd skip writing those itxs out, and 3151 * would break the semantics of zil_commit(); thus, we're 3152 * verifying that truth before we return to the caller. 3153 */ 3154 ASSERT(list_is_empty(&zilog->zl_lwb_list)); 3155 ASSERT3P(zilog->zl_last_lwb_opened, ==, NULL); 3156 for (int i = 0; i < TXG_SIZE; i++) 3157 ASSERT3P(zilog->zl_itxg[i].itxg_itxs, ==, NULL); 3158 return; 3159 } 3160 3161 /* 3162 * If the ZIL is suspended, we don't want to dirty it by calling 3163 * zil_commit_itx_assign() below, nor can we write out 3164 * lwbs like would be done in zil_commit_write(). Thus, we 3165 * simply rely on txg_wait_synced() to maintain the necessary 3166 * semantics, and avoid calling those functions altogether. 3167 */ 3168 if (zilog->zl_suspend > 0) { 3169 txg_wait_synced(zilog->zl_dmu_pool, 0); 3170 return; 3171 } 3172 3173 zil_commit_impl(zilog, foid); 3174 } 3175 3176 void 3177 zil_commit_impl(zilog_t *zilog, uint64_t foid) 3178 { 3179 ZIL_STAT_BUMP(zilog, zil_commit_count); 3180 3181 /* 3182 * Move the "async" itxs for the specified foid to the "sync" 3183 * queues, such that they will be later committed (or skipped) 3184 * to an lwb when zil_process_commit_list() is called. 3185 * 3186 * Since these "async" itxs must be committed prior to this 3187 * call to zil_commit returning, we must perform this operation 3188 * before we call zil_commit_itx_assign(). 3189 */ 3190 zil_async_to_sync(zilog, foid); 3191 3192 /* 3193 * We allocate a new "waiter" structure which will initially be 3194 * linked to the commit itx using the itx's "itx_private" field. 3195 * Since the commit itx doesn't represent any on-disk state, 3196 * when it's committed to an lwb, rather than copying the its 3197 * lr_t into the lwb's buffer, the commit itx's "waiter" will be 3198 * added to the lwb's list of waiters. Then, when the lwb is 3199 * committed to stable storage, each waiter in the lwb's list of 3200 * waiters will be marked "done", and signalled. 3201 * 3202 * We must create the waiter and assign the commit itx prior to 3203 * calling zil_commit_writer(), or else our specific commit itx 3204 * is not guaranteed to be committed to an lwb prior to calling 3205 * zil_commit_waiter(). 3206 */ 3207 zil_commit_waiter_t *zcw = zil_alloc_commit_waiter(); 3208 zil_commit_itx_assign(zilog, zcw); 3209 3210 zil_commit_writer(zilog, zcw); 3211 zil_commit_waiter(zilog, zcw); 3212 3213 if (zcw->zcw_zio_error != 0) { 3214 /* 3215 * If there was an error writing out the ZIL blocks that 3216 * this thread is waiting on, then we fallback to 3217 * relying on spa_sync() to write out the data this 3218 * thread is waiting on. Obviously this has performance 3219 * implications, but the expectation is for this to be 3220 * an exceptional case, and shouldn't occur often. 3221 */ 3222 DTRACE_PROBE2(zil__commit__io__error, 3223 zilog_t *, zilog, zil_commit_waiter_t *, zcw); 3224 txg_wait_synced(zilog->zl_dmu_pool, 0); 3225 } 3226 3227 zil_free_commit_waiter(zcw); 3228 } 3229 3230 /* 3231 * Called in syncing context to free committed log blocks and update log header. 3232 */ 3233 void 3234 zil_sync(zilog_t *zilog, dmu_tx_t *tx) 3235 { 3236 zil_header_t *zh = zil_header_in_syncing_context(zilog); 3237 uint64_t txg = dmu_tx_get_txg(tx); 3238 spa_t *spa = zilog->zl_spa; 3239 uint64_t *replayed_seq = &zilog->zl_replayed_seq[txg & TXG_MASK]; 3240 lwb_t *lwb; 3241 3242 /* 3243 * We don't zero out zl_destroy_txg, so make sure we don't try 3244 * to destroy it twice. 3245 */ 3246 if (spa_sync_pass(spa) != 1) 3247 return; 3248 3249 zil_lwb_flush_wait_all(zilog, txg); 3250 3251 mutex_enter(&zilog->zl_lock); 3252 3253 ASSERT(zilog->zl_stop_sync == 0); 3254 3255 if (*replayed_seq != 0) { 3256 ASSERT(zh->zh_replay_seq < *replayed_seq); 3257 zh->zh_replay_seq = *replayed_seq; 3258 *replayed_seq = 0; 3259 } 3260 3261 if (zilog->zl_destroy_txg == txg) { 3262 blkptr_t blk = zh->zh_log; 3263 dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os); 3264 3265 ASSERT(list_head(&zilog->zl_lwb_list) == NULL); 3266 3267 memset(zh, 0, sizeof (zil_header_t)); 3268 memset(zilog->zl_replayed_seq, 0, 3269 sizeof (zilog->zl_replayed_seq)); 3270 3271 if (zilog->zl_keep_first) { 3272 /* 3273 * If this block was part of log chain that couldn't 3274 * be claimed because a device was missing during 3275 * zil_claim(), but that device later returns, 3276 * then this block could erroneously appear valid. 3277 * To guard against this, assign a new GUID to the new 3278 * log chain so it doesn't matter what blk points to. 3279 */ 3280 zil_init_log_chain(zilog, &blk); 3281 zh->zh_log = blk; 3282 } else { 3283 /* 3284 * A destroyed ZIL chain can't contain any TX_SETSAXATTR 3285 * records. So, deactivate the feature for this dataset. 3286 * We activate it again when we start a new ZIL chain. 3287 */ 3288 if (dsl_dataset_feature_is_active(ds, 3289 SPA_FEATURE_ZILSAXATTR)) 3290 dsl_dataset_deactivate_feature(ds, 3291 SPA_FEATURE_ZILSAXATTR, tx); 3292 } 3293 } 3294 3295 while ((lwb = list_head(&zilog->zl_lwb_list)) != NULL) { 3296 zh->zh_log = lwb->lwb_blk; 3297 if (lwb->lwb_buf != NULL || lwb->lwb_max_txg > txg) 3298 break; 3299 list_remove(&zilog->zl_lwb_list, lwb); 3300 zio_free(spa, txg, &lwb->lwb_blk); 3301 zil_free_lwb(zilog, lwb); 3302 3303 /* 3304 * If we don't have anything left in the lwb list then 3305 * we've had an allocation failure and we need to zero 3306 * out the zil_header blkptr so that we don't end 3307 * up freeing the same block twice. 3308 */ 3309 if (list_head(&zilog->zl_lwb_list) == NULL) 3310 BP_ZERO(&zh->zh_log); 3311 } 3312 3313 /* 3314 * Remove fastwrite on any blocks that have been pre-allocated for 3315 * the next commit. This prevents fastwrite counter pollution by 3316 * unused, long-lived LWBs. 3317 */ 3318 for (; lwb != NULL; lwb = list_next(&zilog->zl_lwb_list, lwb)) { 3319 if (lwb->lwb_fastwrite && !lwb->lwb_write_zio) { 3320 metaslab_fastwrite_unmark(zilog->zl_spa, &lwb->lwb_blk); 3321 lwb->lwb_fastwrite = 0; 3322 } 3323 } 3324 3325 mutex_exit(&zilog->zl_lock); 3326 } 3327 3328 static int 3329 zil_lwb_cons(void *vbuf, void *unused, int kmflag) 3330 { 3331 (void) unused, (void) kmflag; 3332 lwb_t *lwb = vbuf; 3333 list_create(&lwb->lwb_itxs, sizeof (itx_t), offsetof(itx_t, itx_node)); 3334 list_create(&lwb->lwb_waiters, sizeof (zil_commit_waiter_t), 3335 offsetof(zil_commit_waiter_t, zcw_node)); 3336 avl_create(&lwb->lwb_vdev_tree, zil_lwb_vdev_compare, 3337 sizeof (zil_vdev_node_t), offsetof(zil_vdev_node_t, zv_node)); 3338 mutex_init(&lwb->lwb_vdev_lock, NULL, MUTEX_DEFAULT, NULL); 3339 return (0); 3340 } 3341 3342 static void 3343 zil_lwb_dest(void *vbuf, void *unused) 3344 { 3345 (void) unused; 3346 lwb_t *lwb = vbuf; 3347 mutex_destroy(&lwb->lwb_vdev_lock); 3348 avl_destroy(&lwb->lwb_vdev_tree); 3349 list_destroy(&lwb->lwb_waiters); 3350 list_destroy(&lwb->lwb_itxs); 3351 } 3352 3353 void 3354 zil_init(void) 3355 { 3356 zil_lwb_cache = kmem_cache_create("zil_lwb_cache", 3357 sizeof (lwb_t), 0, zil_lwb_cons, zil_lwb_dest, NULL, NULL, NULL, 0); 3358 3359 zil_zcw_cache = kmem_cache_create("zil_zcw_cache", 3360 sizeof (zil_commit_waiter_t), 0, NULL, NULL, NULL, NULL, NULL, 0); 3361 3362 zil_sums_init(&zil_sums_global); 3363 zil_kstats_global = kstat_create("zfs", 0, "zil", "misc", 3364 KSTAT_TYPE_NAMED, sizeof (zil_stats) / sizeof (kstat_named_t), 3365 KSTAT_FLAG_VIRTUAL); 3366 3367 if (zil_kstats_global != NULL) { 3368 zil_kstats_global->ks_data = &zil_stats; 3369 zil_kstats_global->ks_update = zil_kstats_global_update; 3370 zil_kstats_global->ks_private = NULL; 3371 kstat_install(zil_kstats_global); 3372 } 3373 } 3374 3375 void 3376 zil_fini(void) 3377 { 3378 kmem_cache_destroy(zil_zcw_cache); 3379 kmem_cache_destroy(zil_lwb_cache); 3380 3381 if (zil_kstats_global != NULL) { 3382 kstat_delete(zil_kstats_global); 3383 zil_kstats_global = NULL; 3384 } 3385 3386 zil_sums_fini(&zil_sums_global); 3387 } 3388 3389 void 3390 zil_set_sync(zilog_t *zilog, uint64_t sync) 3391 { 3392 zilog->zl_sync = sync; 3393 } 3394 3395 void 3396 zil_set_logbias(zilog_t *zilog, uint64_t logbias) 3397 { 3398 zilog->zl_logbias = logbias; 3399 } 3400 3401 zilog_t * 3402 zil_alloc(objset_t *os, zil_header_t *zh_phys) 3403 { 3404 zilog_t *zilog; 3405 3406 zilog = kmem_zalloc(sizeof (zilog_t), KM_SLEEP); 3407 3408 zilog->zl_header = zh_phys; 3409 zilog->zl_os = os; 3410 zilog->zl_spa = dmu_objset_spa(os); 3411 zilog->zl_dmu_pool = dmu_objset_pool(os); 3412 zilog->zl_destroy_txg = TXG_INITIAL - 1; 3413 zilog->zl_logbias = dmu_objset_logbias(os); 3414 zilog->zl_sync = dmu_objset_syncprop(os); 3415 zilog->zl_dirty_max_txg = 0; 3416 zilog->zl_last_lwb_opened = NULL; 3417 zilog->zl_last_lwb_latency = 0; 3418 zilog->zl_max_block_size = zil_maxblocksize; 3419 3420 mutex_init(&zilog->zl_lock, NULL, MUTEX_DEFAULT, NULL); 3421 mutex_init(&zilog->zl_issuer_lock, NULL, MUTEX_DEFAULT, NULL); 3422 mutex_init(&zilog->zl_lwb_io_lock, NULL, MUTEX_DEFAULT, NULL); 3423 3424 for (int i = 0; i < TXG_SIZE; i++) { 3425 mutex_init(&zilog->zl_itxg[i].itxg_lock, NULL, 3426 MUTEX_DEFAULT, NULL); 3427 } 3428 3429 list_create(&zilog->zl_lwb_list, sizeof (lwb_t), 3430 offsetof(lwb_t, lwb_node)); 3431 3432 list_create(&zilog->zl_itx_commit_list, sizeof (itx_t), 3433 offsetof(itx_t, itx_node)); 3434 3435 cv_init(&zilog->zl_cv_suspend, NULL, CV_DEFAULT, NULL); 3436 cv_init(&zilog->zl_lwb_io_cv, NULL, CV_DEFAULT, NULL); 3437 3438 return (zilog); 3439 } 3440 3441 void 3442 zil_free(zilog_t *zilog) 3443 { 3444 int i; 3445 3446 zilog->zl_stop_sync = 1; 3447 3448 ASSERT0(zilog->zl_suspend); 3449 ASSERT0(zilog->zl_suspending); 3450 3451 ASSERT(list_is_empty(&zilog->zl_lwb_list)); 3452 list_destroy(&zilog->zl_lwb_list); 3453 3454 ASSERT(list_is_empty(&zilog->zl_itx_commit_list)); 3455 list_destroy(&zilog->zl_itx_commit_list); 3456 3457 for (i = 0; i < TXG_SIZE; i++) { 3458 /* 3459 * It's possible for an itx to be generated that doesn't dirty 3460 * a txg (e.g. ztest TX_TRUNCATE). So there's no zil_clean() 3461 * callback to remove the entry. We remove those here. 3462 * 3463 * Also free up the ziltest itxs. 3464 */ 3465 if (zilog->zl_itxg[i].itxg_itxs) 3466 zil_itxg_clean(zilog->zl_itxg[i].itxg_itxs); 3467 mutex_destroy(&zilog->zl_itxg[i].itxg_lock); 3468 } 3469 3470 mutex_destroy(&zilog->zl_issuer_lock); 3471 mutex_destroy(&zilog->zl_lock); 3472 mutex_destroy(&zilog->zl_lwb_io_lock); 3473 3474 cv_destroy(&zilog->zl_cv_suspend); 3475 cv_destroy(&zilog->zl_lwb_io_cv); 3476 3477 kmem_free(zilog, sizeof (zilog_t)); 3478 } 3479 3480 /* 3481 * Open an intent log. 3482 */ 3483 zilog_t * 3484 zil_open(objset_t *os, zil_get_data_t *get_data, zil_sums_t *zil_sums) 3485 { 3486 zilog_t *zilog = dmu_objset_zil(os); 3487 3488 ASSERT3P(zilog->zl_get_data, ==, NULL); 3489 ASSERT3P(zilog->zl_last_lwb_opened, ==, NULL); 3490 ASSERT(list_is_empty(&zilog->zl_lwb_list)); 3491 3492 zilog->zl_get_data = get_data; 3493 zilog->zl_sums = zil_sums; 3494 3495 return (zilog); 3496 } 3497 3498 /* 3499 * Close an intent log. 3500 */ 3501 void 3502 zil_close(zilog_t *zilog) 3503 { 3504 lwb_t *lwb; 3505 uint64_t txg; 3506 3507 if (!dmu_objset_is_snapshot(zilog->zl_os)) { 3508 zil_commit(zilog, 0); 3509 } else { 3510 ASSERT3P(list_tail(&zilog->zl_lwb_list), ==, NULL); 3511 ASSERT0(zilog->zl_dirty_max_txg); 3512 ASSERT3B(zilog_is_dirty(zilog), ==, B_FALSE); 3513 } 3514 3515 mutex_enter(&zilog->zl_lock); 3516 lwb = list_tail(&zilog->zl_lwb_list); 3517 if (lwb == NULL) 3518 txg = zilog->zl_dirty_max_txg; 3519 else 3520 txg = MAX(zilog->zl_dirty_max_txg, lwb->lwb_max_txg); 3521 mutex_exit(&zilog->zl_lock); 3522 3523 /* 3524 * zl_lwb_max_issued_txg may be larger than lwb_max_txg. It depends 3525 * on the time when the dmu_tx transaction is assigned in 3526 * zil_lwb_write_issue(). 3527 */ 3528 mutex_enter(&zilog->zl_lwb_io_lock); 3529 txg = MAX(zilog->zl_lwb_max_issued_txg, txg); 3530 mutex_exit(&zilog->zl_lwb_io_lock); 3531 3532 /* 3533 * We need to use txg_wait_synced() to wait until that txg is synced. 3534 * zil_sync() will guarantee all lwbs up to that txg have been 3535 * written out, flushed, and cleaned. 3536 */ 3537 if (txg != 0) 3538 txg_wait_synced(zilog->zl_dmu_pool, txg); 3539 3540 if (zilog_is_dirty(zilog)) 3541 zfs_dbgmsg("zil (%px) is dirty, txg %llu", zilog, 3542 (u_longlong_t)txg); 3543 if (txg < spa_freeze_txg(zilog->zl_spa)) 3544 VERIFY(!zilog_is_dirty(zilog)); 3545 3546 zilog->zl_get_data = NULL; 3547 3548 /* 3549 * We should have only one lwb left on the list; remove it now. 3550 */ 3551 mutex_enter(&zilog->zl_lock); 3552 lwb = list_head(&zilog->zl_lwb_list); 3553 if (lwb != NULL) { 3554 ASSERT3P(lwb, ==, list_tail(&zilog->zl_lwb_list)); 3555 ASSERT3S(lwb->lwb_state, !=, LWB_STATE_ISSUED); 3556 3557 if (lwb->lwb_fastwrite) 3558 metaslab_fastwrite_unmark(zilog->zl_spa, &lwb->lwb_blk); 3559 3560 list_remove(&zilog->zl_lwb_list, lwb); 3561 zio_buf_free(lwb->lwb_buf, lwb->lwb_sz); 3562 zil_free_lwb(zilog, lwb); 3563 } 3564 mutex_exit(&zilog->zl_lock); 3565 } 3566 3567 static const char *suspend_tag = "zil suspending"; 3568 3569 /* 3570 * Suspend an intent log. While in suspended mode, we still honor 3571 * synchronous semantics, but we rely on txg_wait_synced() to do it. 3572 * On old version pools, we suspend the log briefly when taking a 3573 * snapshot so that it will have an empty intent log. 3574 * 3575 * Long holds are not really intended to be used the way we do here -- 3576 * held for such a short time. A concurrent caller of dsl_dataset_long_held() 3577 * could fail. Therefore we take pains to only put a long hold if it is 3578 * actually necessary. Fortunately, it will only be necessary if the 3579 * objset is currently mounted (or the ZVOL equivalent). In that case it 3580 * will already have a long hold, so we are not really making things any worse. 3581 * 3582 * Ideally, we would locate the existing long-holder (i.e. the zfsvfs_t or 3583 * zvol_state_t), and use their mechanism to prevent their hold from being 3584 * dropped (e.g. VFS_HOLD()). However, that would be even more pain for 3585 * very little gain. 3586 * 3587 * if cookiep == NULL, this does both the suspend & resume. 3588 * Otherwise, it returns with the dataset "long held", and the cookie 3589 * should be passed into zil_resume(). 3590 */ 3591 int 3592 zil_suspend(const char *osname, void **cookiep) 3593 { 3594 objset_t *os; 3595 zilog_t *zilog; 3596 const zil_header_t *zh; 3597 int error; 3598 3599 error = dmu_objset_hold(osname, suspend_tag, &os); 3600 if (error != 0) 3601 return (error); 3602 zilog = dmu_objset_zil(os); 3603 3604 mutex_enter(&zilog->zl_lock); 3605 zh = zilog->zl_header; 3606 3607 if (zh->zh_flags & ZIL_REPLAY_NEEDED) { /* unplayed log */ 3608 mutex_exit(&zilog->zl_lock); 3609 dmu_objset_rele(os, suspend_tag); 3610 return (SET_ERROR(EBUSY)); 3611 } 3612 3613 /* 3614 * Don't put a long hold in the cases where we can avoid it. This 3615 * is when there is no cookie so we are doing a suspend & resume 3616 * (i.e. called from zil_vdev_offline()), and there's nothing to do 3617 * for the suspend because it's already suspended, or there's no ZIL. 3618 */ 3619 if (cookiep == NULL && !zilog->zl_suspending && 3620 (zilog->zl_suspend > 0 || BP_IS_HOLE(&zh->zh_log))) { 3621 mutex_exit(&zilog->zl_lock); 3622 dmu_objset_rele(os, suspend_tag); 3623 return (0); 3624 } 3625 3626 dsl_dataset_long_hold(dmu_objset_ds(os), suspend_tag); 3627 dsl_pool_rele(dmu_objset_pool(os), suspend_tag); 3628 3629 zilog->zl_suspend++; 3630 3631 if (zilog->zl_suspend > 1) { 3632 /* 3633 * Someone else is already suspending it. 3634 * Just wait for them to finish. 3635 */ 3636 3637 while (zilog->zl_suspending) 3638 cv_wait(&zilog->zl_cv_suspend, &zilog->zl_lock); 3639 mutex_exit(&zilog->zl_lock); 3640 3641 if (cookiep == NULL) 3642 zil_resume(os); 3643 else 3644 *cookiep = os; 3645 return (0); 3646 } 3647 3648 /* 3649 * If there is no pointer to an on-disk block, this ZIL must not 3650 * be active (e.g. filesystem not mounted), so there's nothing 3651 * to clean up. 3652 */ 3653 if (BP_IS_HOLE(&zh->zh_log)) { 3654 ASSERT(cookiep != NULL); /* fast path already handled */ 3655 3656 *cookiep = os; 3657 mutex_exit(&zilog->zl_lock); 3658 return (0); 3659 } 3660 3661 /* 3662 * The ZIL has work to do. Ensure that the associated encryption 3663 * key will remain mapped while we are committing the log by 3664 * grabbing a reference to it. If the key isn't loaded we have no 3665 * choice but to return an error until the wrapping key is loaded. 3666 */ 3667 if (os->os_encrypted && 3668 dsl_dataset_create_key_mapping(dmu_objset_ds(os)) != 0) { 3669 zilog->zl_suspend--; 3670 mutex_exit(&zilog->zl_lock); 3671 dsl_dataset_long_rele(dmu_objset_ds(os), suspend_tag); 3672 dsl_dataset_rele(dmu_objset_ds(os), suspend_tag); 3673 return (SET_ERROR(EACCES)); 3674 } 3675 3676 zilog->zl_suspending = B_TRUE; 3677 mutex_exit(&zilog->zl_lock); 3678 3679 /* 3680 * We need to use zil_commit_impl to ensure we wait for all 3681 * LWB_STATE_OPENED and LWB_STATE_ISSUED lwbs to be committed 3682 * to disk before proceeding. If we used zil_commit instead, it 3683 * would just call txg_wait_synced(), because zl_suspend is set. 3684 * txg_wait_synced() doesn't wait for these lwb's to be 3685 * LWB_STATE_FLUSH_DONE before returning. 3686 */ 3687 zil_commit_impl(zilog, 0); 3688 3689 /* 3690 * Now that we've ensured all lwb's are LWB_STATE_FLUSH_DONE, we 3691 * use txg_wait_synced() to ensure the data from the zilog has 3692 * migrated to the main pool before calling zil_destroy(). 3693 */ 3694 txg_wait_synced(zilog->zl_dmu_pool, 0); 3695 3696 zil_destroy(zilog, B_FALSE); 3697 3698 mutex_enter(&zilog->zl_lock); 3699 zilog->zl_suspending = B_FALSE; 3700 cv_broadcast(&zilog->zl_cv_suspend); 3701 mutex_exit(&zilog->zl_lock); 3702 3703 if (os->os_encrypted) 3704 dsl_dataset_remove_key_mapping(dmu_objset_ds(os)); 3705 3706 if (cookiep == NULL) 3707 zil_resume(os); 3708 else 3709 *cookiep = os; 3710 return (0); 3711 } 3712 3713 void 3714 zil_resume(void *cookie) 3715 { 3716 objset_t *os = cookie; 3717 zilog_t *zilog = dmu_objset_zil(os); 3718 3719 mutex_enter(&zilog->zl_lock); 3720 ASSERT(zilog->zl_suspend != 0); 3721 zilog->zl_suspend--; 3722 mutex_exit(&zilog->zl_lock); 3723 dsl_dataset_long_rele(dmu_objset_ds(os), suspend_tag); 3724 dsl_dataset_rele(dmu_objset_ds(os), suspend_tag); 3725 } 3726 3727 typedef struct zil_replay_arg { 3728 zil_replay_func_t *const *zr_replay; 3729 void *zr_arg; 3730 boolean_t zr_byteswap; 3731 char *zr_lr; 3732 } zil_replay_arg_t; 3733 3734 static int 3735 zil_replay_error(zilog_t *zilog, const lr_t *lr, int error) 3736 { 3737 char name[ZFS_MAX_DATASET_NAME_LEN]; 3738 3739 zilog->zl_replaying_seq--; /* didn't actually replay this one */ 3740 3741 dmu_objset_name(zilog->zl_os, name); 3742 3743 cmn_err(CE_WARN, "ZFS replay transaction error %d, " 3744 "dataset %s, seq 0x%llx, txtype %llu %s\n", error, name, 3745 (u_longlong_t)lr->lrc_seq, 3746 (u_longlong_t)(lr->lrc_txtype & ~TX_CI), 3747 (lr->lrc_txtype & TX_CI) ? "CI" : ""); 3748 3749 return (error); 3750 } 3751 3752 static int 3753 zil_replay_log_record(zilog_t *zilog, const lr_t *lr, void *zra, 3754 uint64_t claim_txg) 3755 { 3756 zil_replay_arg_t *zr = zra; 3757 const zil_header_t *zh = zilog->zl_header; 3758 uint64_t reclen = lr->lrc_reclen; 3759 uint64_t txtype = lr->lrc_txtype; 3760 int error = 0; 3761 3762 zilog->zl_replaying_seq = lr->lrc_seq; 3763 3764 if (lr->lrc_seq <= zh->zh_replay_seq) /* already replayed */ 3765 return (0); 3766 3767 if (lr->lrc_txg < claim_txg) /* already committed */ 3768 return (0); 3769 3770 /* Strip case-insensitive bit, still present in log record */ 3771 txtype &= ~TX_CI; 3772 3773 if (txtype == 0 || txtype >= TX_MAX_TYPE) 3774 return (zil_replay_error(zilog, lr, EINVAL)); 3775 3776 /* 3777 * If this record type can be logged out of order, the object 3778 * (lr_foid) may no longer exist. That's legitimate, not an error. 3779 */ 3780 if (TX_OOO(txtype)) { 3781 error = dmu_object_info(zilog->zl_os, 3782 LR_FOID_GET_OBJ(((lr_ooo_t *)lr)->lr_foid), NULL); 3783 if (error == ENOENT || error == EEXIST) 3784 return (0); 3785 } 3786 3787 /* 3788 * Make a copy of the data so we can revise and extend it. 3789 */ 3790 memcpy(zr->zr_lr, lr, reclen); 3791 3792 /* 3793 * If this is a TX_WRITE with a blkptr, suck in the data. 3794 */ 3795 if (txtype == TX_WRITE && reclen == sizeof (lr_write_t)) { 3796 error = zil_read_log_data(zilog, (lr_write_t *)lr, 3797 zr->zr_lr + reclen); 3798 if (error != 0) 3799 return (zil_replay_error(zilog, lr, error)); 3800 } 3801 3802 /* 3803 * The log block containing this lr may have been byteswapped 3804 * so that we can easily examine common fields like lrc_txtype. 3805 * However, the log is a mix of different record types, and only the 3806 * replay vectors know how to byteswap their records. Therefore, if 3807 * the lr was byteswapped, undo it before invoking the replay vector. 3808 */ 3809 if (zr->zr_byteswap) 3810 byteswap_uint64_array(zr->zr_lr, reclen); 3811 3812 /* 3813 * We must now do two things atomically: replay this log record, 3814 * and update the log header sequence number to reflect the fact that 3815 * we did so. At the end of each replay function the sequence number 3816 * is updated if we are in replay mode. 3817 */ 3818 error = zr->zr_replay[txtype](zr->zr_arg, zr->zr_lr, zr->zr_byteswap); 3819 if (error != 0) { 3820 /* 3821 * The DMU's dnode layer doesn't see removes until the txg 3822 * commits, so a subsequent claim can spuriously fail with 3823 * EEXIST. So if we receive any error we try syncing out 3824 * any removes then retry the transaction. Note that we 3825 * specify B_FALSE for byteswap now, so we don't do it twice. 3826 */ 3827 txg_wait_synced(spa_get_dsl(zilog->zl_spa), 0); 3828 error = zr->zr_replay[txtype](zr->zr_arg, zr->zr_lr, B_FALSE); 3829 if (error != 0) 3830 return (zil_replay_error(zilog, lr, error)); 3831 } 3832 return (0); 3833 } 3834 3835 static int 3836 zil_incr_blks(zilog_t *zilog, const blkptr_t *bp, void *arg, uint64_t claim_txg) 3837 { 3838 (void) bp, (void) arg, (void) claim_txg; 3839 3840 zilog->zl_replay_blks++; 3841 3842 return (0); 3843 } 3844 3845 /* 3846 * If this dataset has a non-empty intent log, replay it and destroy it. 3847 */ 3848 void 3849 zil_replay(objset_t *os, void *arg, 3850 zil_replay_func_t *const replay_func[TX_MAX_TYPE]) 3851 { 3852 zilog_t *zilog = dmu_objset_zil(os); 3853 const zil_header_t *zh = zilog->zl_header; 3854 zil_replay_arg_t zr; 3855 3856 if ((zh->zh_flags & ZIL_REPLAY_NEEDED) == 0) { 3857 zil_destroy(zilog, B_TRUE); 3858 return; 3859 } 3860 3861 zr.zr_replay = replay_func; 3862 zr.zr_arg = arg; 3863 zr.zr_byteswap = BP_SHOULD_BYTESWAP(&zh->zh_log); 3864 zr.zr_lr = vmem_alloc(2 * SPA_MAXBLOCKSIZE, KM_SLEEP); 3865 3866 /* 3867 * Wait for in-progress removes to sync before starting replay. 3868 */ 3869 txg_wait_synced(zilog->zl_dmu_pool, 0); 3870 3871 zilog->zl_replay = B_TRUE; 3872 zilog->zl_replay_time = ddi_get_lbolt(); 3873 ASSERT(zilog->zl_replay_blks == 0); 3874 (void) zil_parse(zilog, zil_incr_blks, zil_replay_log_record, &zr, 3875 zh->zh_claim_txg, B_TRUE); 3876 vmem_free(zr.zr_lr, 2 * SPA_MAXBLOCKSIZE); 3877 3878 zil_destroy(zilog, B_FALSE); 3879 txg_wait_synced(zilog->zl_dmu_pool, zilog->zl_destroy_txg); 3880 zilog->zl_replay = B_FALSE; 3881 } 3882 3883 boolean_t 3884 zil_replaying(zilog_t *zilog, dmu_tx_t *tx) 3885 { 3886 if (zilog->zl_sync == ZFS_SYNC_DISABLED) 3887 return (B_TRUE); 3888 3889 if (zilog->zl_replay) { 3890 dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx); 3891 zilog->zl_replayed_seq[dmu_tx_get_txg(tx) & TXG_MASK] = 3892 zilog->zl_replaying_seq; 3893 return (B_TRUE); 3894 } 3895 3896 return (B_FALSE); 3897 } 3898 3899 int 3900 zil_reset(const char *osname, void *arg) 3901 { 3902 (void) arg; 3903 3904 int error = zil_suspend(osname, NULL); 3905 /* EACCES means crypto key not loaded */ 3906 if ((error == EACCES) || (error == EBUSY)) 3907 return (SET_ERROR(error)); 3908 if (error != 0) 3909 return (SET_ERROR(EEXIST)); 3910 return (0); 3911 } 3912 3913 EXPORT_SYMBOL(zil_alloc); 3914 EXPORT_SYMBOL(zil_free); 3915 EXPORT_SYMBOL(zil_open); 3916 EXPORT_SYMBOL(zil_close); 3917 EXPORT_SYMBOL(zil_replay); 3918 EXPORT_SYMBOL(zil_replaying); 3919 EXPORT_SYMBOL(zil_destroy); 3920 EXPORT_SYMBOL(zil_destroy_sync); 3921 EXPORT_SYMBOL(zil_itx_create); 3922 EXPORT_SYMBOL(zil_itx_destroy); 3923 EXPORT_SYMBOL(zil_itx_assign); 3924 EXPORT_SYMBOL(zil_commit); 3925 EXPORT_SYMBOL(zil_claim); 3926 EXPORT_SYMBOL(zil_check_log_chain); 3927 EXPORT_SYMBOL(zil_sync); 3928 EXPORT_SYMBOL(zil_clean); 3929 EXPORT_SYMBOL(zil_suspend); 3930 EXPORT_SYMBOL(zil_resume); 3931 EXPORT_SYMBOL(zil_lwb_add_block); 3932 EXPORT_SYMBOL(zil_bp_tree_add); 3933 EXPORT_SYMBOL(zil_set_sync); 3934 EXPORT_SYMBOL(zil_set_logbias); 3935 EXPORT_SYMBOL(zil_sums_init); 3936 EXPORT_SYMBOL(zil_sums_fini); 3937 EXPORT_SYMBOL(zil_kstat_values_update); 3938 3939 ZFS_MODULE_PARAM(zfs, zfs_, commit_timeout_pct, INT, ZMOD_RW, 3940 "ZIL block open timeout percentage"); 3941 3942 ZFS_MODULE_PARAM(zfs_zil, zil_, replay_disable, INT, ZMOD_RW, 3943 "Disable intent logging replay"); 3944 3945 ZFS_MODULE_PARAM(zfs_zil, zil_, nocacheflush, INT, ZMOD_RW, 3946 "Disable ZIL cache flushes"); 3947 3948 ZFS_MODULE_PARAM(zfs_zil, zil_, slog_bulk, ULONG, ZMOD_RW, 3949 "Limit in bytes slog sync writes per commit"); 3950 3951 ZFS_MODULE_PARAM(zfs_zil, zil_, maxblocksize, INT, ZMOD_RW, 3952 "Limit in bytes of ZIL log block size"); 3953