1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  23  * Copyright (c) 2013 by Delphix. All rights reserved.
  24  */
  25 
  26 /* Portions Copyright 2010 Robert Milkowski */
  27 
  28 #include <sys/zfs_context.h>
  29 #include <sys/spa.h>
  30 #include <sys/dmu.h>
  31 #include <sys/zap.h>
  32 #include <sys/arc.h>
  33 #include <sys/stat.h>
  34 #include <sys/resource.h>
  35 #include <sys/zil.h>
  36 #include <sys/zil_impl.h>
  37 #include <sys/dsl_dataset.h>
  38 #include <sys/vdev_impl.h>
  39 #include <sys/dmu_tx.h>
  40 #include <sys/dsl_pool.h>
  41 
  42 /*
  43  * The zfs intent log (ZIL) saves transaction records of system calls
  44  * that change the file system in memory with enough information
  45  * to be able to replay them. These are stored in memory until
  46  * either the DMU transaction group (txg) commits them to the stable pool
  47  * and they can be discarded, or they are flushed to the stable log
  48  * (also in the pool) due to a fsync, O_DSYNC or other synchronous
  49  * requirement. In the event of a panic or power fail then those log
  50  * records (transactions) are replayed.
  51  *
  52  * There is one ZIL per file system. Its on-disk (pool) format consists
  53  * of 3 parts:
  54  *
  55  *      - ZIL header
  56  *      - ZIL blocks
  57  *      - ZIL records
  58  *
  59  * A log record holds a system call transaction. Log blocks can
  60  * hold many log records and the blocks are chained together.
  61  * Each ZIL block contains a block pointer (blkptr_t) to the next
  62  * ZIL block in the chain. The ZIL header points to the first
  63  * block in the chain. Note there is not a fixed place in the pool
  64  * to hold blocks. They are dynamically allocated and freed as
  65  * needed from the blocks available. Figure X shows the ZIL structure:
  66  */
  67 
  68 /*
  69  * Disable intent logging replay.  This global ZIL switch affects all pools.
  70  */
  71 int zil_replay_disable = 0;
  72 
  73 /*
  74  * Tunable parameter for debugging or performance analysis.  Setting
  75  * zfs_nocacheflush will cause corruption on power loss if a volatile
  76  * out-of-order write cache is enabled.
  77  */
  78 boolean_t zfs_nocacheflush = B_FALSE;
  79 
  80 static kmem_cache_t *zil_lwb_cache;
  81 
  82 static void zil_async_to_sync(zilog_t *zilog, uint64_t foid);
  83 
  84 #define LWB_EMPTY(lwb) ((BP_GET_LSIZE(&lwb->lwb_blk) - \
  85     sizeof (zil_chain_t)) == (lwb->lwb_sz - lwb->lwb_nused))
  86 
  87 
  88 /*
  89  * ziltest is by and large an ugly hack, but very useful in
  90  * checking replay without tedious work.
  91  * When running ziltest we want to keep all itx's and so maintain
  92  * a single list in the zl_itxg[] that uses a high txg: ZILTEST_TXG
  93  * We subtract TXG_CONCURRENT_STATES to allow for common code.
  94  */
  95 #define ZILTEST_TXG (UINT64_MAX - TXG_CONCURRENT_STATES)
  96 
  97 static int
  98 zil_bp_compare(const void *x1, const void *x2)
  99 {
 100         const dva_t *dva1 = &((zil_bp_node_t *)x1)->zn_dva;
 101         const dva_t *dva2 = &((zil_bp_node_t *)x2)->zn_dva;
 102 
 103         if (DVA_GET_VDEV(dva1) < DVA_GET_VDEV(dva2))
 104                 return (-1);
 105         if (DVA_GET_VDEV(dva1) > DVA_GET_VDEV(dva2))
 106                 return (1);
 107 
 108         if (DVA_GET_OFFSET(dva1) < DVA_GET_OFFSET(dva2))
 109                 return (-1);
 110         if (DVA_GET_OFFSET(dva1) > DVA_GET_OFFSET(dva2))
 111                 return (1);
 112 
 113         return (0);
 114 }
 115 
 116 static void
 117 zil_bp_tree_init(zilog_t *zilog)
 118 {
 119         avl_create(&zilog->zl_bp_tree, zil_bp_compare,
 120             sizeof (zil_bp_node_t), offsetof(zil_bp_node_t, zn_node));
 121 }
 122 
 123 static void
 124 zil_bp_tree_fini(zilog_t *zilog)
 125 {
 126         avl_tree_t *t = &zilog->zl_bp_tree;
 127         zil_bp_node_t *zn;
 128         void *cookie = NULL;
 129 
 130         while ((zn = avl_destroy_nodes(t, &cookie)) != NULL)
 131                 kmem_free(zn, sizeof (zil_bp_node_t));
 132 
 133         avl_destroy(t);
 134 }
 135 
 136 int
 137 zil_bp_tree_add(zilog_t *zilog, const blkptr_t *bp)
 138 {
 139         avl_tree_t *t = &zilog->zl_bp_tree;
 140         const dva_t *dva = BP_IDENTITY(bp);
 141         zil_bp_node_t *zn;
 142         avl_index_t where;
 143 
 144         if (avl_find(t, dva, &where) != NULL)
 145                 return (SET_ERROR(EEXIST));
 146 
 147         zn = kmem_alloc(sizeof (zil_bp_node_t), KM_SLEEP);
 148         zn->zn_dva = *dva;
 149         avl_insert(t, zn, where);
 150 
 151         return (0);
 152 }
 153 
 154 static zil_header_t *
 155 zil_header_in_syncing_context(zilog_t *zilog)
 156 {
 157         return ((zil_header_t *)zilog->zl_header);
 158 }
 159 
 160 static void
 161 zil_init_log_chain(zilog_t *zilog, blkptr_t *bp)
 162 {
 163         zio_cksum_t *zc = &bp->blk_cksum;
 164 
 165         zc->zc_word[ZIL_ZC_GUID_0] = spa_get_random(-1ULL);
 166         zc->zc_word[ZIL_ZC_GUID_1] = spa_get_random(-1ULL);
 167         zc->zc_word[ZIL_ZC_OBJSET] = dmu_objset_id(zilog->zl_os);
 168         zc->zc_word[ZIL_ZC_SEQ] = 1ULL;
 169 }
 170 
 171 /*
 172  * Read a log block and make sure it's valid.
 173  */
 174 static int
 175 zil_read_log_block(zilog_t *zilog, const blkptr_t *bp, blkptr_t *nbp, void *dst,
 176     char **end)
 177 {
 178         enum zio_flag zio_flags = ZIO_FLAG_CANFAIL;
 179         uint32_t aflags = ARC_WAIT;
 180         arc_buf_t *abuf = NULL;
 181         zbookmark_t zb;
 182         int error;
 183 
 184         if (zilog->zl_header->zh_claim_txg == 0)
 185                 zio_flags |= ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SCRUB;
 186 
 187         if (!(zilog->zl_header->zh_flags & ZIL_CLAIM_LR_SEQ_VALID))
 188                 zio_flags |= ZIO_FLAG_SPECULATIVE;
 189 
 190         SET_BOOKMARK(&zb, bp->blk_cksum.zc_word[ZIL_ZC_OBJSET],
 191             ZB_ZIL_OBJECT, ZB_ZIL_LEVEL, bp->blk_cksum.zc_word[ZIL_ZC_SEQ]);
 192 
 193         error = arc_read(NULL, zilog->zl_spa, bp, arc_getbuf_func, &abuf,
 194             ZIO_PRIORITY_SYNC_READ, zio_flags, &aflags, &zb);
 195 
 196         if (error == 0) {
 197                 zio_cksum_t cksum = bp->blk_cksum;
 198 
 199                 /*
 200                  * Validate the checksummed log block.
 201                  *
 202                  * Sequence numbers should be... sequential.  The checksum
 203                  * verifier for the next block should be bp's checksum plus 1.
 204                  *
 205                  * Also check the log chain linkage and size used.
 206                  */
 207                 cksum.zc_word[ZIL_ZC_SEQ]++;
 208 
 209                 if (BP_GET_CHECKSUM(bp) == ZIO_CHECKSUM_ZILOG2) {
 210                         zil_chain_t *zilc = abuf->b_data;
 211                         char *lr = (char *)(zilc + 1);
 212                         uint64_t len = zilc->zc_nused - sizeof (zil_chain_t);
 213 
 214                         if (bcmp(&cksum, &zilc->zc_next_blk.blk_cksum,
 215                             sizeof (cksum)) || BP_IS_HOLE(&zilc->zc_next_blk)) {
 216                                 error = SET_ERROR(ECKSUM);
 217                         } else {
 218                                 bcopy(lr, dst, len);
 219                                 *end = (char *)dst + len;
 220                                 *nbp = zilc->zc_next_blk;
 221                         }
 222                 } else {
 223                         char *lr = abuf->b_data;
 224                         uint64_t size = BP_GET_LSIZE(bp);
 225                         zil_chain_t *zilc = (zil_chain_t *)(lr + size) - 1;
 226 
 227                         if (bcmp(&cksum, &zilc->zc_next_blk.blk_cksum,
 228                             sizeof (cksum)) || BP_IS_HOLE(&zilc->zc_next_blk) ||
 229                             (zilc->zc_nused > (size - sizeof (*zilc)))) {
 230                                 error = SET_ERROR(ECKSUM);
 231                         } else {
 232                                 bcopy(lr, dst, zilc->zc_nused);
 233                                 *end = (char *)dst + zilc->zc_nused;
 234                                 *nbp = zilc->zc_next_blk;
 235                         }
 236                 }
 237 
 238                 VERIFY(arc_buf_remove_ref(abuf, &abuf));
 239         }
 240 
 241         return (error);
 242 }
 243 
 244 /*
 245  * Read a TX_WRITE log data block.
 246  */
 247 static int
 248 zil_read_log_data(zilog_t *zilog, const lr_write_t *lr, void *wbuf)
 249 {
 250         enum zio_flag zio_flags = ZIO_FLAG_CANFAIL;
 251         const blkptr_t *bp = &lr->lr_blkptr;
 252         uint32_t aflags = ARC_WAIT;
 253         arc_buf_t *abuf = NULL;
 254         zbookmark_t zb;
 255         int error;
 256 
 257         if (BP_IS_HOLE(bp)) {
 258                 if (wbuf != NULL)
 259                         bzero(wbuf, MAX(BP_GET_LSIZE(bp), lr->lr_length));
 260                 return (0);
 261         }
 262 
 263         if (zilog->zl_header->zh_claim_txg == 0)
 264                 zio_flags |= ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SCRUB;
 265 
 266         SET_BOOKMARK(&zb, dmu_objset_id(zilog->zl_os), lr->lr_foid,
 267             ZB_ZIL_LEVEL, lr->lr_offset / BP_GET_LSIZE(bp));
 268 
 269         error = arc_read(NULL, zilog->zl_spa, bp, arc_getbuf_func, &abuf,
 270             ZIO_PRIORITY_SYNC_READ, zio_flags, &aflags, &zb);
 271 
 272         if (error == 0) {
 273                 if (wbuf != NULL)
 274                         bcopy(abuf->b_data, wbuf, arc_buf_size(abuf));
 275                 (void) arc_buf_remove_ref(abuf, &abuf);
 276         }
 277 
 278         return (error);
 279 }
 280 
 281 /*
 282  * Parse the intent log, and call parse_func for each valid record within.
 283  */
 284 int
 285 zil_parse(zilog_t *zilog, zil_parse_blk_func_t *parse_blk_func,
 286     zil_parse_lr_func_t *parse_lr_func, void *arg, uint64_t txg)
 287 {
 288         const zil_header_t *zh = zilog->zl_header;
 289         boolean_t claimed = !!zh->zh_claim_txg;
 290         uint64_t claim_blk_seq = claimed ? zh->zh_claim_blk_seq : UINT64_MAX;
 291         uint64_t claim_lr_seq = claimed ? zh->zh_claim_lr_seq : UINT64_MAX;
 292         uint64_t max_blk_seq = 0;
 293         uint64_t max_lr_seq = 0;
 294         uint64_t blk_count = 0;
 295         uint64_t lr_count = 0;
 296         blkptr_t blk, next_blk;
 297         char *lrbuf, *lrp;
 298         int error = 0;
 299 
 300         /*
 301          * Old logs didn't record the maximum zh_claim_lr_seq.
 302          */
 303         if (!(zh->zh_flags & ZIL_CLAIM_LR_SEQ_VALID))
 304                 claim_lr_seq = UINT64_MAX;
 305 
 306         /*
 307          * Starting at the block pointed to by zh_log we read the log chain.
 308          * For each block in the chain we strongly check that block to
 309          * ensure its validity.  We stop when an invalid block is found.
 310          * For each block pointer in the chain we call parse_blk_func().
 311          * For each record in each valid block we call parse_lr_func().
 312          * If the log has been claimed, stop if we encounter a sequence
 313          * number greater than the highest claimed sequence number.
 314          */
 315         lrbuf = zio_buf_alloc(SPA_MAXBLOCKSIZE);
 316         zil_bp_tree_init(zilog);
 317 
 318         for (blk = zh->zh_log; !BP_IS_HOLE(&blk); blk = next_blk) {
 319                 uint64_t blk_seq = blk.blk_cksum.zc_word[ZIL_ZC_SEQ];
 320                 int reclen;
 321                 char *end;
 322 
 323                 if (blk_seq > claim_blk_seq)
 324                         break;
 325                 if ((error = parse_blk_func(zilog, &blk, arg, txg)) != 0)
 326                         break;
 327                 ASSERT3U(max_blk_seq, <, blk_seq);
 328                 max_blk_seq = blk_seq;
 329                 blk_count++;
 330 
 331                 if (max_lr_seq == claim_lr_seq && max_blk_seq == claim_blk_seq)
 332                         break;
 333 
 334                 error = zil_read_log_block(zilog, &blk, &next_blk, lrbuf, &end);
 335                 if (error != 0)
 336                         break;
 337 
 338                 for (lrp = lrbuf; lrp < end; lrp += reclen) {
 339                         lr_t *lr = (lr_t *)lrp;
 340                         reclen = lr->lrc_reclen;
 341                         ASSERT3U(reclen, >=, sizeof (lr_t));
 342                         if (lr->lrc_seq > claim_lr_seq)
 343                                 goto done;
 344                         if ((error = parse_lr_func(zilog, lr, arg, txg)) != 0)
 345                                 goto done;
 346                         ASSERT3U(max_lr_seq, <, lr->lrc_seq);
 347                         max_lr_seq = lr->lrc_seq;
 348                         lr_count++;
 349                 }
 350         }
 351 done:
 352         zilog->zl_parse_error = error;
 353         zilog->zl_parse_blk_seq = max_blk_seq;
 354         zilog->zl_parse_lr_seq = max_lr_seq;
 355         zilog->zl_parse_blk_count = blk_count;
 356         zilog->zl_parse_lr_count = lr_count;
 357 
 358         ASSERT(!claimed || !(zh->zh_flags & ZIL_CLAIM_LR_SEQ_VALID) ||
 359             (max_blk_seq == claim_blk_seq && max_lr_seq == claim_lr_seq));
 360 
 361         zil_bp_tree_fini(zilog);
 362         zio_buf_free(lrbuf, SPA_MAXBLOCKSIZE);
 363 
 364         return (error);
 365 }
 366 
 367 static int
 368 zil_claim_log_block(zilog_t *zilog, blkptr_t *bp, void *tx, uint64_t first_txg)
 369 {
 370         /*
 371          * Claim log block if not already committed and not already claimed.
 372          * If tx == NULL, just verify that the block is claimable.
 373          */
 374         if (bp->blk_birth < first_txg || zil_bp_tree_add(zilog, bp) != 0)
 375                 return (0);
 376 
 377         return (zio_wait(zio_claim(NULL, zilog->zl_spa,
 378             tx == NULL ? 0 : first_txg, bp, spa_claim_notify, NULL,
 379             ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE | ZIO_FLAG_SCRUB)));
 380 }
 381 
 382 static int
 383 zil_claim_log_record(zilog_t *zilog, lr_t *lrc, void *tx, uint64_t first_txg)
 384 {
 385         lr_write_t *lr = (lr_write_t *)lrc;
 386         int error;
 387 
 388         if (lrc->lrc_txtype != TX_WRITE)
 389                 return (0);
 390 
 391         /*
 392          * If the block is not readable, don't claim it.  This can happen
 393          * in normal operation when a log block is written to disk before
 394          * some of the dmu_sync() blocks it points to.  In this case, the
 395          * transaction cannot have been committed to anyone (we would have
 396          * waited for all writes to be stable first), so it is semantically
 397          * correct to declare this the end of the log.
 398          */
 399         if (lr->lr_blkptr.blk_birth >= first_txg &&
 400             (error = zil_read_log_data(zilog, lr, NULL)) != 0)
 401                 return (error);
 402         return (zil_claim_log_block(zilog, &lr->lr_blkptr, tx, first_txg));
 403 }
 404 
 405 /* ARGSUSED */
 406 static int
 407 zil_free_log_block(zilog_t *zilog, blkptr_t *bp, void *tx, uint64_t claim_txg)
 408 {
 409         zio_free_zil(zilog->zl_spa, dmu_tx_get_txg(tx), bp);
 410 
 411         return (0);
 412 }
 413 
 414 static int
 415 zil_free_log_record(zilog_t *zilog, lr_t *lrc, void *tx, uint64_t claim_txg)
 416 {
 417         lr_write_t *lr = (lr_write_t *)lrc;
 418         blkptr_t *bp = &lr->lr_blkptr;
 419 
 420         /*
 421          * If we previously claimed it, we need to free it.
 422          */
 423         if (claim_txg != 0 && lrc->lrc_txtype == TX_WRITE &&
 424             bp->blk_birth >= claim_txg && zil_bp_tree_add(zilog, bp) == 0)
 425                 zio_free(zilog->zl_spa, dmu_tx_get_txg(tx), bp);
 426 
 427         return (0);
 428 }
 429 
 430 static lwb_t *
 431 zil_alloc_lwb(zilog_t *zilog, blkptr_t *bp, uint64_t txg)
 432 {
 433         lwb_t *lwb;
 434 
 435         lwb = kmem_cache_alloc(zil_lwb_cache, KM_SLEEP);
 436         lwb->lwb_zilog = zilog;
 437         lwb->lwb_blk = *bp;
 438         lwb->lwb_buf = zio_buf_alloc(BP_GET_LSIZE(bp));
 439         lwb->lwb_max_txg = txg;
 440         lwb->lwb_zio = NULL;
 441         lwb->lwb_tx = NULL;
 442         if (BP_GET_CHECKSUM(bp) == ZIO_CHECKSUM_ZILOG2) {
 443                 lwb->lwb_nused = sizeof (zil_chain_t);
 444                 lwb->lwb_sz = BP_GET_LSIZE(bp);
 445         } else {
 446                 lwb->lwb_nused = 0;
 447                 lwb->lwb_sz = BP_GET_LSIZE(bp) - sizeof (zil_chain_t);
 448         }
 449 
 450         mutex_enter(&zilog->zl_lock);
 451         list_insert_tail(&zilog->zl_lwb_list, lwb);
 452         mutex_exit(&zilog->zl_lock);
 453 
 454         return (lwb);
 455 }
 456 
 457 /*
 458  * Called when we create in-memory log transactions so that we know
 459  * to cleanup the itxs at the end of spa_sync().
 460  */
 461 void
 462 zilog_dirty(zilog_t *zilog, uint64_t txg)
 463 {
 464         dsl_pool_t *dp = zilog->zl_dmu_pool;
 465         dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os);
 466 
 467         if (dsl_dataset_is_snapshot(ds))
 468                 panic("dirtying snapshot!");
 469 
 470         if (txg_list_add(&dp->dp_dirty_zilogs, zilog, txg)) {
 471                 /* up the hold count until we can be written out */
 472                 dmu_buf_add_ref(ds->ds_dbuf, zilog);
 473         }
 474 }
 475 
 476 boolean_t
 477 zilog_is_dirty(zilog_t *zilog)
 478 {
 479         dsl_pool_t *dp = zilog->zl_dmu_pool;
 480 
 481         for (int t = 0; t < TXG_SIZE; t++) {
 482                 if (txg_list_member(&dp->dp_dirty_zilogs, zilog, t))
 483                         return (B_TRUE);
 484         }
 485         return (B_FALSE);
 486 }
 487 
 488 /*
 489  * Create an on-disk intent log.
 490  */
 491 static lwb_t *
 492 zil_create(zilog_t *zilog)
 493 {
 494         const zil_header_t *zh = zilog->zl_header;
 495         lwb_t *lwb = NULL;
 496         uint64_t txg = 0;
 497         dmu_tx_t *tx = NULL;
 498         blkptr_t blk;
 499         int error = 0;
 500 
 501         /*
 502          * Wait for any previous destroy to complete.
 503          */
 504         txg_wait_synced(zilog->zl_dmu_pool, zilog->zl_destroy_txg);
 505 
 506         ASSERT(zh->zh_claim_txg == 0);
 507         ASSERT(zh->zh_replay_seq == 0);
 508 
 509         blk = zh->zh_log;
 510 
 511         /*
 512          * Allocate an initial log block if:
 513          *    - there isn't one already
 514          *    - the existing block is the wrong endianess
 515          */
 516         if (BP_IS_HOLE(&blk) || BP_SHOULD_BYTESWAP(&blk)) {
 517                 tx = dmu_tx_create(zilog->zl_os);
 518                 VERIFY(dmu_tx_assign(tx, TXG_WAIT) == 0);
 519                 dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx);
 520                 txg = dmu_tx_get_txg(tx);
 521 
 522                 if (!BP_IS_HOLE(&blk)) {
 523                         zio_free_zil(zilog->zl_spa, txg, &blk);
 524                         BP_ZERO(&blk);
 525                 }
 526 
 527                 error = zio_alloc_zil(zilog->zl_spa, txg, &blk, NULL,
 528                     ZIL_MIN_BLKSZ, zilog->zl_logbias == ZFS_LOGBIAS_LATENCY);
 529 
 530                 if (error == 0)
 531                         zil_init_log_chain(zilog, &blk);
 532         }
 533 
 534         /*
 535          * Allocate a log write buffer (lwb) for the first log block.
 536          */
 537         if (error == 0)
 538                 lwb = zil_alloc_lwb(zilog, &blk, txg);
 539 
 540         /*
 541          * If we just allocated the first log block, commit our transaction
 542          * and wait for zil_sync() to stuff the block poiner into zh_log.
 543          * (zh is part of the MOS, so we cannot modify it in open context.)
 544          */
 545         if (tx != NULL) {
 546                 dmu_tx_commit(tx);
 547                 txg_wait_synced(zilog->zl_dmu_pool, txg);
 548         }
 549 
 550         ASSERT(bcmp(&blk, &zh->zh_log, sizeof (blk)) == 0);
 551 
 552         return (lwb);
 553 }
 554 
 555 /*
 556  * In one tx, free all log blocks and clear the log header.
 557  * If keep_first is set, then we're replaying a log with no content.
 558  * We want to keep the first block, however, so that the first
 559  * synchronous transaction doesn't require a txg_wait_synced()
 560  * in zil_create().  We don't need to txg_wait_synced() here either
 561  * when keep_first is set, because both zil_create() and zil_destroy()
 562  * will wait for any in-progress destroys to complete.
 563  */
 564 void
 565 zil_destroy(zilog_t *zilog, boolean_t keep_first)
 566 {
 567         const zil_header_t *zh = zilog->zl_header;
 568         lwb_t *lwb;
 569         dmu_tx_t *tx;
 570         uint64_t txg;
 571 
 572         /*
 573          * Wait for any previous destroy to complete.
 574          */
 575         txg_wait_synced(zilog->zl_dmu_pool, zilog->zl_destroy_txg);
 576 
 577         zilog->zl_old_header = *zh;          /* debugging aid */
 578 
 579         if (BP_IS_HOLE(&zh->zh_log))
 580                 return;
 581 
 582         tx = dmu_tx_create(zilog->zl_os);
 583         VERIFY(dmu_tx_assign(tx, TXG_WAIT) == 0);
 584         dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx);
 585         txg = dmu_tx_get_txg(tx);
 586 
 587         mutex_enter(&zilog->zl_lock);
 588 
 589         ASSERT3U(zilog->zl_destroy_txg, <, txg);
 590         zilog->zl_destroy_txg = txg;
 591         zilog->zl_keep_first = keep_first;
 592 
 593         if (!list_is_empty(&zilog->zl_lwb_list)) {
 594                 ASSERT(zh->zh_claim_txg == 0);
 595                 VERIFY(!keep_first);
 596                 while ((lwb = list_head(&zilog->zl_lwb_list)) != NULL) {
 597                         list_remove(&zilog->zl_lwb_list, lwb);
 598                         if (lwb->lwb_buf != NULL)
 599                                 zio_buf_free(lwb->lwb_buf, lwb->lwb_sz);
 600                         zio_free_zil(zilog->zl_spa, txg, &lwb->lwb_blk);
 601                         kmem_cache_free(zil_lwb_cache, lwb);
 602                 }
 603         } else if (!keep_first) {
 604                 zil_destroy_sync(zilog, tx);
 605         }
 606         mutex_exit(&zilog->zl_lock);
 607 
 608         dmu_tx_commit(tx);
 609 }
 610 
 611 void
 612 zil_destroy_sync(zilog_t *zilog, dmu_tx_t *tx)
 613 {
 614         ASSERT(list_is_empty(&zilog->zl_lwb_list));
 615         (void) zil_parse(zilog, zil_free_log_block,
 616             zil_free_log_record, tx, zilog->zl_header->zh_claim_txg);
 617 }
 618 
 619 int
 620 zil_claim(const char *osname, void *txarg)
 621 {
 622         dmu_tx_t *tx = txarg;
 623         uint64_t first_txg = dmu_tx_get_txg(tx);
 624         zilog_t *zilog;
 625         zil_header_t *zh;
 626         objset_t *os;
 627         int error;
 628 
 629         error = dmu_objset_own(osname, DMU_OST_ANY, B_FALSE, FTAG, &os);
 630         if (error != 0) {
 631                 cmn_err(CE_WARN, "can't open objset for %s", osname);
 632                 return (0);
 633         }
 634 
 635         zilog = dmu_objset_zil(os);
 636         zh = zil_header_in_syncing_context(zilog);
 637 
 638         if (spa_get_log_state(zilog->zl_spa) == SPA_LOG_CLEAR) {
 639                 if (!BP_IS_HOLE(&zh->zh_log))
 640                         zio_free_zil(zilog->zl_spa, first_txg, &zh->zh_log);
 641                 BP_ZERO(&zh->zh_log);
 642                 dsl_dataset_dirty(dmu_objset_ds(os), tx);
 643                 dmu_objset_disown(os, FTAG);
 644                 return (0);
 645         }
 646 
 647         /*
 648          * Claim all log blocks if we haven't already done so, and remember
 649          * the highest claimed sequence number.  This ensures that if we can
 650          * read only part of the log now (e.g. due to a missing device),
 651          * but we can read the entire log later, we will not try to replay
 652          * or destroy beyond the last block we successfully claimed.
 653          */
 654         ASSERT3U(zh->zh_claim_txg, <=, first_txg);
 655         if (zh->zh_claim_txg == 0 && !BP_IS_HOLE(&zh->zh_log)) {
 656                 (void) zil_parse(zilog, zil_claim_log_block,
 657                     zil_claim_log_record, tx, first_txg);
 658                 zh->zh_claim_txg = first_txg;
 659                 zh->zh_claim_blk_seq = zilog->zl_parse_blk_seq;
 660                 zh->zh_claim_lr_seq = zilog->zl_parse_lr_seq;
 661                 if (zilog->zl_parse_lr_count || zilog->zl_parse_blk_count > 1)
 662                         zh->zh_flags |= ZIL_REPLAY_NEEDED;
 663                 zh->zh_flags |= ZIL_CLAIM_LR_SEQ_VALID;
 664                 dsl_dataset_dirty(dmu_objset_ds(os), tx);
 665         }
 666 
 667         ASSERT3U(first_txg, ==, (spa_last_synced_txg(zilog->zl_spa) + 1));
 668         dmu_objset_disown(os, FTAG);
 669         return (0);
 670 }
 671 
 672 /*
 673  * Check the log by walking the log chain.
 674  * Checksum errors are ok as they indicate the end of the chain.
 675  * Any other error (no device or read failure) returns an error.
 676  */
 677 int
 678 zil_check_log_chain(const char *osname, void *tx)
 679 {
 680         zilog_t *zilog;
 681         objset_t *os;
 682         blkptr_t *bp;
 683         int error;
 684 
 685         ASSERT(tx == NULL);
 686 
 687         error = dmu_objset_hold(osname, FTAG, &os);
 688         if (error != 0) {
 689                 cmn_err(CE_WARN, "can't open objset for %s", osname);
 690                 return (0);
 691         }
 692 
 693         zilog = dmu_objset_zil(os);
 694         bp = (blkptr_t *)&zilog->zl_header->zh_log;
 695 
 696         /*
 697          * Check the first block and determine if it's on a log device
 698          * which may have been removed or faulted prior to loading this
 699          * pool.  If so, there's no point in checking the rest of the log
 700          * as its content should have already been synced to the pool.
 701          */
 702         if (!BP_IS_HOLE(bp)) {
 703                 vdev_t *vd;
 704                 boolean_t valid = B_TRUE;
 705 
 706                 spa_config_enter(os->os_spa, SCL_STATE, FTAG, RW_READER);
 707                 vd = vdev_lookup_top(os->os_spa, DVA_GET_VDEV(&bp->blk_dva[0]));
 708                 if (vd->vdev_islog && vdev_is_dead(vd))
 709                         valid = vdev_log_state_valid(vd);
 710                 spa_config_exit(os->os_spa, SCL_STATE, FTAG);
 711 
 712                 if (!valid) {
 713                         dmu_objset_rele(os, FTAG);
 714                         return (0);
 715                 }
 716         }
 717 
 718         /*
 719          * Because tx == NULL, zil_claim_log_block() will not actually claim
 720          * any blocks, but just determine whether it is possible to do so.
 721          * In addition to checking the log chain, zil_claim_log_block()
 722          * will invoke zio_claim() with a done func of spa_claim_notify(),
 723          * which will update spa_max_claim_txg.  See spa_load() for details.
 724          */
 725         error = zil_parse(zilog, zil_claim_log_block, zil_claim_log_record, tx,
 726             zilog->zl_header->zh_claim_txg ? -1ULL : spa_first_txg(os->os_spa));
 727 
 728         dmu_objset_rele(os, FTAG);
 729 
 730         return ((error == ECKSUM || error == ENOENT) ? 0 : error);
 731 }
 732 
 733 static int
 734 zil_vdev_compare(const void *x1, const void *x2)
 735 {
 736         const uint64_t v1 = ((zil_vdev_node_t *)x1)->zv_vdev;
 737         const uint64_t v2 = ((zil_vdev_node_t *)x2)->zv_vdev;
 738 
 739         if (v1 < v2)
 740                 return (-1);
 741         if (v1 > v2)
 742                 return (1);
 743 
 744         return (0);
 745 }
 746 
 747 void
 748 zil_add_block(zilog_t *zilog, const blkptr_t *bp)
 749 {
 750         avl_tree_t *t = &zilog->zl_vdev_tree;
 751         avl_index_t where;
 752         zil_vdev_node_t *zv, zvsearch;
 753         int ndvas = BP_GET_NDVAS(bp);
 754         int i;
 755 
 756         if (zfs_nocacheflush)
 757                 return;
 758 
 759         ASSERT(zilog->zl_writer);
 760 
 761         /*
 762          * Even though we're zl_writer, we still need a lock because the
 763          * zl_get_data() callbacks may have dmu_sync() done callbacks
 764          * that will run concurrently.
 765          */
 766         mutex_enter(&zilog->zl_vdev_lock);
 767         for (i = 0; i < ndvas; i++) {
 768                 zvsearch.zv_vdev = DVA_GET_VDEV(&bp->blk_dva[i]);
 769                 if (avl_find(t, &zvsearch, &where) == NULL) {
 770                         zv = kmem_alloc(sizeof (*zv), KM_SLEEP);
 771                         zv->zv_vdev = zvsearch.zv_vdev;
 772                         avl_insert(t, zv, where);
 773                 }
 774         }
 775         mutex_exit(&zilog->zl_vdev_lock);
 776 }
 777 
 778 static void
 779 zil_flush_vdevs(zilog_t *zilog)
 780 {
 781         spa_t *spa = zilog->zl_spa;
 782         avl_tree_t *t = &zilog->zl_vdev_tree;
 783         void *cookie = NULL;
 784         zil_vdev_node_t *zv;
 785         zio_t *zio;
 786 
 787         ASSERT(zilog->zl_writer);
 788 
 789         /*
 790          * We don't need zl_vdev_lock here because we're the zl_writer,
 791          * and all zl_get_data() callbacks are done.
 792          */
 793         if (avl_numnodes(t) == 0)
 794                 return;
 795 
 796         spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);
 797 
 798         zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL);
 799 
 800         while ((zv = avl_destroy_nodes(t, &cookie)) != NULL) {
 801                 vdev_t *vd = vdev_lookup_top(spa, zv->zv_vdev);
 802                 if (vd != NULL)
 803                         zio_flush(zio, vd);
 804                 kmem_free(zv, sizeof (*zv));
 805         }
 806 
 807         /*
 808          * Wait for all the flushes to complete.  Not all devices actually
 809          * support the DKIOCFLUSHWRITECACHE ioctl, so it's OK if it fails.
 810          */
 811         (void) zio_wait(zio);
 812 
 813         spa_config_exit(spa, SCL_STATE, FTAG);
 814 }
 815 
 816 /*
 817  * Function called when a log block write completes
 818  */
 819 static void
 820 zil_lwb_write_done(zio_t *zio)
 821 {
 822         lwb_t *lwb = zio->io_private;
 823         zilog_t *zilog = lwb->lwb_zilog;
 824         dmu_tx_t *tx = lwb->lwb_tx;
 825 
 826         ASSERT(BP_GET_COMPRESS(zio->io_bp) == ZIO_COMPRESS_OFF);
 827         ASSERT(BP_GET_TYPE(zio->io_bp) == DMU_OT_INTENT_LOG);
 828         ASSERT(BP_GET_LEVEL(zio->io_bp) == 0);
 829         ASSERT(BP_GET_BYTEORDER(zio->io_bp) == ZFS_HOST_BYTEORDER);
 830         ASSERT(!BP_IS_GANG(zio->io_bp));
 831         ASSERT(!BP_IS_HOLE(zio->io_bp));
 832         ASSERT(zio->io_bp->blk_fill == 0);
 833 
 834         /*
 835          * Ensure the lwb buffer pointer is cleared before releasing
 836          * the txg. If we have had an allocation failure and
 837          * the txg is waiting to sync then we want want zil_sync()
 838          * to remove the lwb so that it's not picked up as the next new
 839          * one in zil_commit_writer(). zil_sync() will only remove
 840          * the lwb if lwb_buf is null.
 841          */
 842         zio_buf_free(lwb->lwb_buf, lwb->lwb_sz);
 843         mutex_enter(&zilog->zl_lock);
 844         lwb->lwb_buf = NULL;
 845         lwb->lwb_tx = NULL;
 846         mutex_exit(&zilog->zl_lock);
 847 
 848         /*
 849          * Now that we've written this log block, we have a stable pointer
 850          * to the next block in the chain, so it's OK to let the txg in
 851          * which we allocated the next block sync.
 852          */
 853         dmu_tx_commit(tx);
 854 }
 855 
 856 /*
 857  * Initialize the io for a log block.
 858  */
 859 static void
 860 zil_lwb_write_init(zilog_t *zilog, lwb_t *lwb)
 861 {
 862         zbookmark_t zb;
 863 
 864         SET_BOOKMARK(&zb, lwb->lwb_blk.blk_cksum.zc_word[ZIL_ZC_OBJSET],
 865             ZB_ZIL_OBJECT, ZB_ZIL_LEVEL,
 866             lwb->lwb_blk.blk_cksum.zc_word[ZIL_ZC_SEQ]);
 867 
 868         if (zilog->zl_root_zio == NULL) {
 869                 zilog->zl_root_zio = zio_root(zilog->zl_spa, NULL, NULL,
 870                     ZIO_FLAG_CANFAIL);
 871         }
 872         if (lwb->lwb_zio == NULL) {
 873                 lwb->lwb_zio = zio_rewrite(zilog->zl_root_zio, zilog->zl_spa,
 874                     0, &lwb->lwb_blk, lwb->lwb_buf, BP_GET_LSIZE(&lwb->lwb_blk),
 875                     zil_lwb_write_done, lwb, ZIO_PRIORITY_LOG_WRITE,
 876                     ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_PROPAGATE, &zb);
 877         }
 878 }
 879 
 880 /*
 881  * Define a limited set of intent log block sizes.
 882  *
 883  * These must be a multiple of 4KB. Note only the amount used (again
 884  * aligned to 4KB) actually gets written. However, we can't always just
 885  * allocate SPA_MAXBLOCKSIZE as the slog space could be exhausted.
 886  */
 887 uint64_t zil_block_buckets[] = {
 888     4096,               /* non TX_WRITE */
 889     8192+4096,          /* data base */
 890     32*1024 + 4096,     /* NFS writes */
 891     UINT64_MAX
 892 };
 893 
 894 /*
 895  * Use the slog as long as the logbias is 'latency' and the current commit size
 896  * is less than the limit or the total list size is less than 2X the limit.
 897  * Limit checking is disabled by setting zil_slog_limit to UINT64_MAX.
 898  */
 899 uint64_t zil_slog_limit = 1024 * 1024;
 900 #define USE_SLOG(zilog) (((zilog)->zl_logbias == ZFS_LOGBIAS_LATENCY) && \
 901         (((zilog)->zl_cur_used < zil_slog_limit) || \
 902         ((zilog)->zl_itx_list_sz < (zil_slog_limit << 1))))
 903 
 904 /*
 905  * Start a log block write and advance to the next log block.
 906  * Calls are serialized.
 907  */
 908 static lwb_t *
 909 zil_lwb_write_start(zilog_t *zilog, lwb_t *lwb)
 910 {
 911         lwb_t *nlwb = NULL;
 912         zil_chain_t *zilc;
 913         spa_t *spa = zilog->zl_spa;
 914         blkptr_t *bp;
 915         dmu_tx_t *tx;
 916         uint64_t txg;
 917         uint64_t zil_blksz, wsz;
 918         int i, error;
 919 
 920         if (BP_GET_CHECKSUM(&lwb->lwb_blk) == ZIO_CHECKSUM_ZILOG2) {
 921                 zilc = (zil_chain_t *)lwb->lwb_buf;
 922                 bp = &zilc->zc_next_blk;
 923         } else {
 924                 zilc = (zil_chain_t *)(lwb->lwb_buf + lwb->lwb_sz);
 925                 bp = &zilc->zc_next_blk;
 926         }
 927 
 928         ASSERT(lwb->lwb_nused <= lwb->lwb_sz);
 929 
 930         /*
 931          * Allocate the next block and save its address in this block
 932          * before writing it in order to establish the log chain.
 933          * Note that if the allocation of nlwb synced before we wrote
 934          * the block that points at it (lwb), we'd leak it if we crashed.
 935          * Therefore, we don't do dmu_tx_commit() until zil_lwb_write_done().
 936          * We dirty the dataset to ensure that zil_sync() will be called
 937          * to clean up in the event of allocation failure or I/O failure.
 938          */
 939         tx = dmu_tx_create(zilog->zl_os);
 940         VERIFY(dmu_tx_assign(tx, TXG_WAIT) == 0);
 941         dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx);
 942         txg = dmu_tx_get_txg(tx);
 943 
 944         lwb->lwb_tx = tx;
 945 
 946         /*
 947          * Log blocks are pre-allocated. Here we select the size of the next
 948          * block, based on size used in the last block.
 949          * - first find the smallest bucket that will fit the block from a
 950          *   limited set of block sizes. This is because it's faster to write
 951          *   blocks allocated from the same metaslab as they are adjacent or
 952          *   close.
 953          * - next find the maximum from the new suggested size and an array of
 954          *   previous sizes. This lessens a picket fence effect of wrongly
 955          *   guesssing the size if we have a stream of say 2k, 64k, 2k, 64k
 956          *   requests.
 957          *
 958          * Note we only write what is used, but we can't just allocate
 959          * the maximum block size because we can exhaust the available
 960          * pool log space.
 961          */
 962         zil_blksz = zilog->zl_cur_used + sizeof (zil_chain_t);
 963         for (i = 0; zil_blksz > zil_block_buckets[i]; i++)
 964                 continue;
 965         zil_blksz = zil_block_buckets[i];
 966         if (zil_blksz == UINT64_MAX)
 967                 zil_blksz = SPA_MAXBLOCKSIZE;
 968         zilog->zl_prev_blks[zilog->zl_prev_rotor] = zil_blksz;
 969         for (i = 0; i < ZIL_PREV_BLKS; i++)
 970                 zil_blksz = MAX(zil_blksz, zilog->zl_prev_blks[i]);
 971         zilog->zl_prev_rotor = (zilog->zl_prev_rotor + 1) & (ZIL_PREV_BLKS - 1);
 972 
 973         BP_ZERO(bp);
 974         /* pass the old blkptr in order to spread log blocks across devs */
 975         error = zio_alloc_zil(spa, txg, bp, &lwb->lwb_blk, zil_blksz,
 976             USE_SLOG(zilog));
 977         if (error == 0) {
 978                 ASSERT3U(bp->blk_birth, ==, txg);
 979                 bp->blk_cksum = lwb->lwb_blk.blk_cksum;
 980                 bp->blk_cksum.zc_word[ZIL_ZC_SEQ]++;
 981 
 982                 /*
 983                  * Allocate a new log write buffer (lwb).
 984                  */
 985                 nlwb = zil_alloc_lwb(zilog, bp, txg);
 986 
 987                 /* Record the block for later vdev flushing */
 988                 zil_add_block(zilog, &lwb->lwb_blk);
 989         }
 990 
 991         if (BP_GET_CHECKSUM(&lwb->lwb_blk) == ZIO_CHECKSUM_ZILOG2) {
 992                 /* For Slim ZIL only write what is used. */
 993                 wsz = P2ROUNDUP_TYPED(lwb->lwb_nused, ZIL_MIN_BLKSZ, uint64_t);
 994                 ASSERT3U(wsz, <=, lwb->lwb_sz);
 995                 zio_shrink(lwb->lwb_zio, wsz);
 996 
 997         } else {
 998                 wsz = lwb->lwb_sz;
 999         }
1000 
1001         zilc->zc_pad = 0;
1002         zilc->zc_nused = lwb->lwb_nused;
1003         zilc->zc_eck.zec_cksum = lwb->lwb_blk.blk_cksum;
1004 
1005         /*
1006          * clear unused data for security
1007          */
1008         bzero(lwb->lwb_buf + lwb->lwb_nused, wsz - lwb->lwb_nused);
1009 
1010         zio_nowait(lwb->lwb_zio); /* Kick off the write for the old log block */
1011 
1012         /*
1013          * If there was an allocation failure then nlwb will be null which
1014          * forces a txg_wait_synced().
1015          */
1016         return (nlwb);
1017 }
1018 
1019 static lwb_t *
1020 zil_lwb_commit(zilog_t *zilog, itx_t *itx, lwb_t *lwb)
1021 {
1022         lr_t *lrc = &itx->itx_lr; /* common log record */
1023         lr_write_t *lrw = (lr_write_t *)lrc;
1024         char *lr_buf;
1025         uint64_t txg = lrc->lrc_txg;
1026         uint64_t reclen = lrc->lrc_reclen;
1027         uint64_t dlen = 0;
1028 
1029         if (lwb == NULL)
1030                 return (NULL);
1031 
1032         ASSERT(lwb->lwb_buf != NULL);
1033         ASSERT(zilog_is_dirty(zilog) ||
1034             spa_freeze_txg(zilog->zl_spa) != UINT64_MAX);
1035 
1036         if (lrc->lrc_txtype == TX_WRITE && itx->itx_wr_state == WR_NEED_COPY)
1037                 dlen = P2ROUNDUP_TYPED(
1038                     lrw->lr_length, sizeof (uint64_t), uint64_t);
1039 
1040         zilog->zl_cur_used += (reclen + dlen);
1041 
1042         zil_lwb_write_init(zilog, lwb);
1043 
1044         /*
1045          * If this record won't fit in the current log block, start a new one.
1046          */
1047         if (lwb->lwb_nused + reclen + dlen > lwb->lwb_sz) {
1048                 lwb = zil_lwb_write_start(zilog, lwb);
1049                 if (lwb == NULL)
1050                         return (NULL);
1051                 zil_lwb_write_init(zilog, lwb);
1052                 ASSERT(LWB_EMPTY(lwb));
1053                 if (lwb->lwb_nused + reclen + dlen > lwb->lwb_sz) {
1054                         txg_wait_synced(zilog->zl_dmu_pool, txg);
1055                         return (lwb);
1056                 }
1057         }
1058 
1059         lr_buf = lwb->lwb_buf + lwb->lwb_nused;
1060         bcopy(lrc, lr_buf, reclen);
1061         lrc = (lr_t *)lr_buf;
1062         lrw = (lr_write_t *)lrc;
1063 
1064         /*
1065          * If it's a write, fetch the data or get its blkptr as appropriate.
1066          */
1067         if (lrc->lrc_txtype == TX_WRITE) {
1068                 if (txg > spa_freeze_txg(zilog->zl_spa))
1069                         txg_wait_synced(zilog->zl_dmu_pool, txg);
1070                 if (itx->itx_wr_state != WR_COPIED) {
1071                         char *dbuf;
1072                         int error;
1073 
1074                         if (dlen) {
1075                                 ASSERT(itx->itx_wr_state == WR_NEED_COPY);
1076                                 dbuf = lr_buf + reclen;
1077                                 lrw->lr_common.lrc_reclen += dlen;
1078                         } else {
1079                                 ASSERT(itx->itx_wr_state == WR_INDIRECT);
1080                                 dbuf = NULL;
1081                         }
1082                         error = zilog->zl_get_data(
1083                             itx->itx_private, lrw, dbuf, lwb->lwb_zio);
1084                         if (error == EIO) {
1085                                 txg_wait_synced(zilog->zl_dmu_pool, txg);
1086                                 return (lwb);
1087                         }
1088                         if (error != 0) {
1089                                 ASSERT(error == ENOENT || error == EEXIST ||
1090                                     error == EALREADY);
1091                                 return (lwb);
1092                         }
1093                 }
1094         }
1095 
1096         /*
1097          * We're actually making an entry, so update lrc_seq to be the
1098          * log record sequence number.  Note that this is generally not
1099          * equal to the itx sequence number because not all transactions
1100          * are synchronous, and sometimes spa_sync() gets there first.
1101          */
1102         lrc->lrc_seq = ++zilog->zl_lr_seq; /* we are single threaded */
1103         lwb->lwb_nused += reclen + dlen;
1104         lwb->lwb_max_txg = MAX(lwb->lwb_max_txg, txg);
1105         ASSERT3U(lwb->lwb_nused, <=, lwb->lwb_sz);
1106         ASSERT0(P2PHASE(lwb->lwb_nused, sizeof (uint64_t)));
1107 
1108         return (lwb);
1109 }
1110 
1111 itx_t *
1112 zil_itx_create(uint64_t txtype, size_t lrsize)
1113 {
1114         itx_t *itx;
1115 
1116         lrsize = P2ROUNDUP_TYPED(lrsize, sizeof (uint64_t), size_t);
1117 
1118         itx = kmem_alloc(offsetof(itx_t, itx_lr) + lrsize, KM_SLEEP);
1119         itx->itx_lr.lrc_txtype = txtype;
1120         itx->itx_lr.lrc_reclen = lrsize;
1121         itx->itx_sod = lrsize; /* if write & WR_NEED_COPY will be increased */
1122         itx->itx_lr.lrc_seq = 0;     /* defensive */
1123         itx->itx_sync = B_TRUE;              /* default is synchronous */
1124 
1125         return (itx);
1126 }
1127 
1128 void
1129 zil_itx_destroy(itx_t *itx)
1130 {
1131         kmem_free(itx, offsetof(itx_t, itx_lr) + itx->itx_lr.lrc_reclen);
1132 }
1133 
1134 /*
1135  * Free up the sync and async itxs. The itxs_t has already been detached
1136  * so no locks are needed.
1137  */
1138 static void
1139 zil_itxg_clean(itxs_t *itxs)
1140 {
1141         itx_t *itx;
1142         list_t *list;
1143         avl_tree_t *t;
1144         void *cookie;
1145         itx_async_node_t *ian;
1146 
1147         list = &itxs->i_sync_list;
1148         while ((itx = list_head(list)) != NULL) {
1149                 list_remove(list, itx);
1150                 kmem_free(itx, offsetof(itx_t, itx_lr) +
1151                     itx->itx_lr.lrc_reclen);
1152         }
1153 
1154         cookie = NULL;
1155         t = &itxs->i_async_tree;
1156         while ((ian = avl_destroy_nodes(t, &cookie)) != NULL) {
1157                 list = &ian->ia_list;
1158                 while ((itx = list_head(list)) != NULL) {
1159                         list_remove(list, itx);
1160                         kmem_free(itx, offsetof(itx_t, itx_lr) +
1161                             itx->itx_lr.lrc_reclen);
1162                 }
1163                 list_destroy(list);
1164                 kmem_free(ian, sizeof (itx_async_node_t));
1165         }
1166         avl_destroy(t);
1167 
1168         kmem_free(itxs, sizeof (itxs_t));
1169 }
1170 
1171 static int
1172 zil_aitx_compare(const void *x1, const void *x2)
1173 {
1174         const uint64_t o1 = ((itx_async_node_t *)x1)->ia_foid;
1175         const uint64_t o2 = ((itx_async_node_t *)x2)->ia_foid;
1176 
1177         if (o1 < o2)
1178                 return (-1);
1179         if (o1 > o2)
1180                 return (1);
1181 
1182         return (0);
1183 }
1184 
1185 /*
1186  * Remove all async itx with the given oid.
1187  */
1188 static void
1189 zil_remove_async(zilog_t *zilog, uint64_t oid)
1190 {
1191         uint64_t otxg, txg;
1192         itx_async_node_t *ian;
1193         avl_tree_t *t;
1194         avl_index_t where;
1195         list_t clean_list;
1196         itx_t *itx;
1197 
1198         ASSERT(oid != 0);
1199         list_create(&clean_list, sizeof (itx_t), offsetof(itx_t, itx_node));
1200 
1201         if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) /* ziltest support */
1202                 otxg = ZILTEST_TXG;
1203         else
1204                 otxg = spa_last_synced_txg(zilog->zl_spa) + 1;
1205 
1206         for (txg = otxg; txg < (otxg + TXG_CONCURRENT_STATES); txg++) {
1207                 itxg_t *itxg = &zilog->zl_itxg[txg & TXG_MASK];
1208 
1209                 mutex_enter(&itxg->itxg_lock);
1210                 if (itxg->itxg_txg != txg) {
1211                         mutex_exit(&itxg->itxg_lock);
1212                         continue;
1213                 }
1214 
1215                 /*
1216                  * Locate the object node and append its list.
1217                  */
1218                 t = &itxg->itxg_itxs->i_async_tree;
1219                 ian = avl_find(t, &oid, &where);
1220                 if (ian != NULL)
1221                         list_move_tail(&clean_list, &ian->ia_list);
1222                 mutex_exit(&itxg->itxg_lock);
1223         }
1224         while ((itx = list_head(&clean_list)) != NULL) {
1225                 list_remove(&clean_list, itx);
1226                 kmem_free(itx, offsetof(itx_t, itx_lr) +
1227                     itx->itx_lr.lrc_reclen);
1228         }
1229         list_destroy(&clean_list);
1230 }
1231 
1232 void
1233 zil_itx_assign(zilog_t *zilog, itx_t *itx, dmu_tx_t *tx)
1234 {
1235         uint64_t txg;
1236         itxg_t *itxg;
1237         itxs_t *itxs, *clean = NULL;
1238 
1239         /*
1240          * Object ids can be re-instantiated in the next txg so
1241          * remove any async transactions to avoid future leaks.
1242          * This can happen if a fsync occurs on the re-instantiated
1243          * object for a WR_INDIRECT or WR_NEED_COPY write, which gets
1244          * the new file data and flushes a write record for the old object.
1245          */
1246         if ((itx->itx_lr.lrc_txtype & ~TX_CI) == TX_REMOVE)
1247                 zil_remove_async(zilog, itx->itx_oid);
1248 
1249         /*
1250          * Ensure the data of a renamed file is committed before the rename.
1251          */
1252         if ((itx->itx_lr.lrc_txtype & ~TX_CI) == TX_RENAME)
1253                 zil_async_to_sync(zilog, itx->itx_oid);
1254 
1255         if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX)
1256                 txg = ZILTEST_TXG;
1257         else
1258                 txg = dmu_tx_get_txg(tx);
1259 
1260         itxg = &zilog->zl_itxg[txg & TXG_MASK];
1261         mutex_enter(&itxg->itxg_lock);
1262         itxs = itxg->itxg_itxs;
1263         if (itxg->itxg_txg != txg) {
1264                 if (itxs != NULL) {
1265                         /*
1266                          * The zil_clean callback hasn't got around to cleaning
1267                          * this itxg. Save the itxs for release below.
1268                          * This should be rare.
1269                          */
1270                         atomic_add_64(&zilog->zl_itx_list_sz, -itxg->itxg_sod);
1271                         itxg->itxg_sod = 0;
1272                         clean = itxg->itxg_itxs;
1273                 }
1274                 ASSERT(itxg->itxg_sod == 0);
1275                 itxg->itxg_txg = txg;
1276                 itxs = itxg->itxg_itxs = kmem_zalloc(sizeof (itxs_t), KM_SLEEP);
1277 
1278                 list_create(&itxs->i_sync_list, sizeof (itx_t),
1279                     offsetof(itx_t, itx_node));
1280                 avl_create(&itxs->i_async_tree, zil_aitx_compare,
1281                     sizeof (itx_async_node_t),
1282                     offsetof(itx_async_node_t, ia_node));
1283         }
1284         if (itx->itx_sync) {
1285                 list_insert_tail(&itxs->i_sync_list, itx);
1286                 atomic_add_64(&zilog->zl_itx_list_sz, itx->itx_sod);
1287                 itxg->itxg_sod += itx->itx_sod;
1288         } else {
1289                 avl_tree_t *t = &itxs->i_async_tree;
1290                 uint64_t foid = ((lr_ooo_t *)&itx->itx_lr)->lr_foid;
1291                 itx_async_node_t *ian;
1292                 avl_index_t where;
1293 
1294                 ian = avl_find(t, &foid, &where);
1295                 if (ian == NULL) {
1296                         ian = kmem_alloc(sizeof (itx_async_node_t), KM_SLEEP);
1297                         list_create(&ian->ia_list, sizeof (itx_t),
1298                             offsetof(itx_t, itx_node));
1299                         ian->ia_foid = foid;
1300                         avl_insert(t, ian, where);
1301                 }
1302                 list_insert_tail(&ian->ia_list, itx);
1303         }
1304 
1305         itx->itx_lr.lrc_txg = dmu_tx_get_txg(tx);
1306         zilog_dirty(zilog, txg);
1307         mutex_exit(&itxg->itxg_lock);
1308 
1309         /* Release the old itxs now we've dropped the lock */
1310         if (clean != NULL)
1311                 zil_itxg_clean(clean);
1312 }
1313 
1314 /*
1315  * If there are any in-memory intent log transactions which have now been
1316  * synced then start up a taskq to free them. We should only do this after we
1317  * have written out the uberblocks (i.e. txg has been comitted) so that
1318  * don't inadvertently clean out in-memory log records that would be required
1319  * by zil_commit().
1320  */
1321 void
1322 zil_clean(zilog_t *zilog, uint64_t synced_txg)
1323 {
1324         itxg_t *itxg = &zilog->zl_itxg[synced_txg & TXG_MASK];
1325         itxs_t *clean_me;
1326 
1327         mutex_enter(&itxg->itxg_lock);
1328         if (itxg->itxg_itxs == NULL || itxg->itxg_txg == ZILTEST_TXG) {
1329                 mutex_exit(&itxg->itxg_lock);
1330                 return;
1331         }
1332         ASSERT3U(itxg->itxg_txg, <=, synced_txg);
1333         ASSERT(itxg->itxg_txg != 0);
1334         ASSERT(zilog->zl_clean_taskq != NULL);
1335         atomic_add_64(&zilog->zl_itx_list_sz, -itxg->itxg_sod);
1336         itxg->itxg_sod = 0;
1337         clean_me = itxg->itxg_itxs;
1338         itxg->itxg_itxs = NULL;
1339         itxg->itxg_txg = 0;
1340         mutex_exit(&itxg->itxg_lock);
1341         /*
1342          * Preferably start a task queue to free up the old itxs but
1343          * if taskq_dispatch can't allocate resources to do that then
1344          * free it in-line. This should be rare. Note, using TQ_SLEEP
1345          * created a bad performance problem.
1346          */
1347         if (taskq_dispatch(zilog->zl_clean_taskq,
1348             (void (*)(void *))zil_itxg_clean, clean_me, TQ_NOSLEEP) == NULL)
1349                 zil_itxg_clean(clean_me);
1350 }
1351 
1352 /*
1353  * Get the list of itxs to commit into zl_itx_commit_list.
1354  */
1355 static void
1356 zil_get_commit_list(zilog_t *zilog)
1357 {
1358         uint64_t otxg, txg;
1359         list_t *commit_list = &zilog->zl_itx_commit_list;
1360         uint64_t push_sod = 0;
1361 
1362         if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) /* ziltest support */
1363                 otxg = ZILTEST_TXG;
1364         else
1365                 otxg = spa_last_synced_txg(zilog->zl_spa) + 1;
1366 
1367         for (txg = otxg; txg < (otxg + TXG_CONCURRENT_STATES); txg++) {
1368                 itxg_t *itxg = &zilog->zl_itxg[txg & TXG_MASK];
1369 
1370                 mutex_enter(&itxg->itxg_lock);
1371                 if (itxg->itxg_txg != txg) {
1372                         mutex_exit(&itxg->itxg_lock);
1373                         continue;
1374                 }
1375 
1376                 list_move_tail(commit_list, &itxg->itxg_itxs->i_sync_list);
1377                 push_sod += itxg->itxg_sod;
1378                 itxg->itxg_sod = 0;
1379 
1380                 mutex_exit(&itxg->itxg_lock);
1381         }
1382         atomic_add_64(&zilog->zl_itx_list_sz, -push_sod);
1383 }
1384 
1385 /*
1386  * Move the async itxs for a specified object to commit into sync lists.
1387  */
1388 static void
1389 zil_async_to_sync(zilog_t *zilog, uint64_t foid)
1390 {
1391         uint64_t otxg, txg;
1392         itx_async_node_t *ian;
1393         avl_tree_t *t;
1394         avl_index_t where;
1395 
1396         if (spa_freeze_txg(zilog->zl_spa) != UINT64_MAX) /* ziltest support */
1397                 otxg = ZILTEST_TXG;
1398         else
1399                 otxg = spa_last_synced_txg(zilog->zl_spa) + 1;
1400 
1401         for (txg = otxg; txg < (otxg + TXG_CONCURRENT_STATES); txg++) {
1402                 itxg_t *itxg = &zilog->zl_itxg[txg & TXG_MASK];
1403 
1404                 mutex_enter(&itxg->itxg_lock);
1405                 if (itxg->itxg_txg != txg) {
1406                         mutex_exit(&itxg->itxg_lock);
1407                         continue;
1408                 }
1409 
1410                 /*
1411                  * If a foid is specified then find that node and append its
1412                  * list. Otherwise walk the tree appending all the lists
1413                  * to the sync list. We add to the end rather than the
1414                  * beginning to ensure the create has happened.
1415                  */
1416                 t = &itxg->itxg_itxs->i_async_tree;
1417                 if (foid != 0) {
1418                         ian = avl_find(t, &foid, &where);
1419                         if (ian != NULL) {
1420                                 list_move_tail(&itxg->itxg_itxs->i_sync_list,
1421                                     &ian->ia_list);
1422                         }
1423                 } else {
1424                         void *cookie = NULL;
1425 
1426                         while ((ian = avl_destroy_nodes(t, &cookie)) != NULL) {
1427                                 list_move_tail(&itxg->itxg_itxs->i_sync_list,
1428                                     &ian->ia_list);
1429                                 list_destroy(&ian->ia_list);
1430                                 kmem_free(ian, sizeof (itx_async_node_t));
1431                         }
1432                 }
1433                 mutex_exit(&itxg->itxg_lock);
1434         }
1435 }
1436 
1437 static void
1438 zil_commit_writer(zilog_t *zilog)
1439 {
1440         uint64_t txg;
1441         itx_t *itx;
1442         lwb_t *lwb;
1443         spa_t *spa = zilog->zl_spa;
1444         int error = 0;
1445 
1446         ASSERT(zilog->zl_root_zio == NULL);
1447 
1448         mutex_exit(&zilog->zl_lock);
1449 
1450         zil_get_commit_list(zilog);
1451 
1452         /*
1453          * Return if there's nothing to commit before we dirty the fs by
1454          * calling zil_create().
1455          */
1456         if (list_head(&zilog->zl_itx_commit_list) == NULL) {
1457                 mutex_enter(&zilog->zl_lock);
1458                 return;
1459         }
1460 
1461         if (zilog->zl_suspend) {
1462                 lwb = NULL;
1463         } else {
1464                 lwb = list_tail(&zilog->zl_lwb_list);
1465                 if (lwb == NULL)
1466                         lwb = zil_create(zilog);
1467         }
1468 
1469         DTRACE_PROBE1(zil__cw1, zilog_t *, zilog);
1470         while (itx = list_head(&zilog->zl_itx_commit_list)) {
1471                 txg = itx->itx_lr.lrc_txg;
1472                 ASSERT(txg);
1473 
1474                 if (txg > spa_last_synced_txg(spa) || txg > spa_freeze_txg(spa))
1475                         lwb = zil_lwb_commit(zilog, itx, lwb);
1476                 list_remove(&zilog->zl_itx_commit_list, itx);
1477                 kmem_free(itx, offsetof(itx_t, itx_lr)
1478                     + itx->itx_lr.lrc_reclen);
1479         }
1480         DTRACE_PROBE1(zil__cw2, zilog_t *, zilog);
1481 
1482         /* write the last block out */
1483         if (lwb != NULL && lwb->lwb_zio != NULL)
1484                 lwb = zil_lwb_write_start(zilog, lwb);
1485 
1486         zilog->zl_cur_used = 0;
1487 
1488         /*
1489          * Wait if necessary for the log blocks to be on stable storage.
1490          */
1491         if (zilog->zl_root_zio) {
1492                 error = zio_wait(zilog->zl_root_zio);
1493                 zilog->zl_root_zio = NULL;
1494                 zil_flush_vdevs(zilog);
1495         }
1496 
1497         if (error || lwb == NULL)
1498                 txg_wait_synced(zilog->zl_dmu_pool, 0);
1499 
1500         mutex_enter(&zilog->zl_lock);
1501 
1502         /*
1503          * Remember the highest committed log sequence number for ztest.
1504          * We only update this value when all the log writes succeeded,
1505          * because ztest wants to ASSERT that it got the whole log chain.
1506          */
1507         if (error == 0 && lwb != NULL)
1508                 zilog->zl_commit_lr_seq = zilog->zl_lr_seq;
1509 }
1510 
1511 /*
1512  * Commit zfs transactions to stable storage.
1513  * If foid is 0 push out all transactions, otherwise push only those
1514  * for that object or might reference that object.
1515  *
1516  * itxs are committed in batches. In a heavily stressed zil there will be
1517  * a commit writer thread who is writing out a bunch of itxs to the log
1518  * for a set of committing threads (cthreads) in the same batch as the writer.
1519  * Those cthreads are all waiting on the same cv for that batch.
1520  *
1521  * There will also be a different and growing batch of threads that are
1522  * waiting to commit (qthreads). When the committing batch completes
1523  * a transition occurs such that the cthreads exit and the qthreads become
1524  * cthreads. One of the new cthreads becomes the writer thread for the
1525  * batch. Any new threads arriving become new qthreads.
1526  *
1527  * Only 2 condition variables are needed and there's no transition
1528  * between the two cvs needed. They just flip-flop between qthreads
1529  * and cthreads.
1530  *
1531  * Using this scheme we can efficiently wakeup up only those threads
1532  * that have been committed.
1533  */
1534 void
1535 zil_commit(zilog_t *zilog, uint64_t foid)
1536 {
1537         uint64_t mybatch;
1538 
1539         if (zilog->zl_sync == ZFS_SYNC_DISABLED)
1540                 return;
1541 
1542         /* move the async itxs for the foid to the sync queues */
1543         zil_async_to_sync(zilog, foid);
1544 
1545         mutex_enter(&zilog->zl_lock);
1546         mybatch = zilog->zl_next_batch;
1547         while (zilog->zl_writer) {
1548                 cv_wait(&zilog->zl_cv_batch[mybatch & 1], &zilog->zl_lock);
1549                 if (mybatch <= zilog->zl_com_batch) {
1550                         mutex_exit(&zilog->zl_lock);
1551                         return;
1552                 }
1553         }
1554 
1555         zilog->zl_next_batch++;
1556         zilog->zl_writer = B_TRUE;
1557         zil_commit_writer(zilog);
1558         zilog->zl_com_batch = mybatch;
1559         zilog->zl_writer = B_FALSE;
1560         mutex_exit(&zilog->zl_lock);
1561 
1562         /* wake up one thread to become the next writer */
1563         cv_signal(&zilog->zl_cv_batch[(mybatch+1) & 1]);
1564 
1565         /* wake up all threads waiting for this batch to be committed */
1566         cv_broadcast(&zilog->zl_cv_batch[mybatch & 1]);
1567 }
1568 
1569 /*
1570  * Called in syncing context to free committed log blocks and update log header.
1571  */
1572 void
1573 zil_sync(zilog_t *zilog, dmu_tx_t *tx)
1574 {
1575         zil_header_t *zh = zil_header_in_syncing_context(zilog);
1576         uint64_t txg = dmu_tx_get_txg(tx);
1577         spa_t *spa = zilog->zl_spa;
1578         uint64_t *replayed_seq = &zilog->zl_replayed_seq[txg & TXG_MASK];
1579         lwb_t *lwb;
1580 
1581         /*
1582          * We don't zero out zl_destroy_txg, so make sure we don't try
1583          * to destroy it twice.
1584          */
1585         if (spa_sync_pass(spa) != 1)
1586                 return;
1587 
1588         mutex_enter(&zilog->zl_lock);
1589 
1590         ASSERT(zilog->zl_stop_sync == 0);
1591 
1592         if (*replayed_seq != 0) {
1593                 ASSERT(zh->zh_replay_seq < *replayed_seq);
1594                 zh->zh_replay_seq = *replayed_seq;
1595                 *replayed_seq = 0;
1596         }
1597 
1598         if (zilog->zl_destroy_txg == txg) {
1599                 blkptr_t blk = zh->zh_log;
1600 
1601                 ASSERT(list_head(&zilog->zl_lwb_list) == NULL);
1602 
1603                 bzero(zh, sizeof (zil_header_t));
1604                 bzero(zilog->zl_replayed_seq, sizeof (zilog->zl_replayed_seq));
1605 
1606                 if (zilog->zl_keep_first) {
1607                         /*
1608                          * If this block was part of log chain that couldn't
1609                          * be claimed because a device was missing during
1610                          * zil_claim(), but that device later returns,
1611                          * then this block could erroneously appear valid.
1612                          * To guard against this, assign a new GUID to the new
1613                          * log chain so it doesn't matter what blk points to.
1614                          */
1615                         zil_init_log_chain(zilog, &blk);
1616                         zh->zh_log = blk;
1617                 }
1618         }
1619 
1620         while ((lwb = list_head(&zilog->zl_lwb_list)) != NULL) {
1621                 zh->zh_log = lwb->lwb_blk;
1622                 if (lwb->lwb_buf != NULL || lwb->lwb_max_txg > txg)
1623                         break;
1624                 list_remove(&zilog->zl_lwb_list, lwb);
1625                 zio_free_zil(spa, txg, &lwb->lwb_blk);
1626                 kmem_cache_free(zil_lwb_cache, lwb);
1627 
1628                 /*
1629                  * If we don't have anything left in the lwb list then
1630                  * we've had an allocation failure and we need to zero
1631                  * out the zil_header blkptr so that we don't end
1632                  * up freeing the same block twice.
1633                  */
1634                 if (list_head(&zilog->zl_lwb_list) == NULL)
1635                         BP_ZERO(&zh->zh_log);
1636         }
1637         mutex_exit(&zilog->zl_lock);
1638 }
1639 
1640 void
1641 zil_init(void)
1642 {
1643         zil_lwb_cache = kmem_cache_create("zil_lwb_cache",
1644             sizeof (struct lwb), 0, NULL, NULL, NULL, NULL, NULL, 0);
1645 }
1646 
1647 void
1648 zil_fini(void)
1649 {
1650         kmem_cache_destroy(zil_lwb_cache);
1651 }
1652 
1653 void
1654 zil_set_sync(zilog_t *zilog, uint64_t sync)
1655 {
1656         zilog->zl_sync = sync;
1657 }
1658 
1659 void
1660 zil_set_logbias(zilog_t *zilog, uint64_t logbias)
1661 {
1662         zilog->zl_logbias = logbias;
1663 }
1664 
1665 zilog_t *
1666 zil_alloc(objset_t *os, zil_header_t *zh_phys)
1667 {
1668         zilog_t *zilog;
1669 
1670         zilog = kmem_zalloc(sizeof (zilog_t), KM_SLEEP);
1671 
1672         zilog->zl_header = zh_phys;
1673         zilog->zl_os = os;
1674         zilog->zl_spa = dmu_objset_spa(os);
1675         zilog->zl_dmu_pool = dmu_objset_pool(os);
1676         zilog->zl_destroy_txg = TXG_INITIAL - 1;
1677         zilog->zl_logbias = dmu_objset_logbias(os);
1678         zilog->zl_sync = dmu_objset_syncprop(os);
1679         zilog->zl_next_batch = 1;
1680 
1681         mutex_init(&zilog->zl_lock, NULL, MUTEX_DEFAULT, NULL);
1682 
1683         for (int i = 0; i < TXG_SIZE; i++) {
1684                 mutex_init(&zilog->zl_itxg[i].itxg_lock, NULL,
1685                     MUTEX_DEFAULT, NULL);
1686         }
1687 
1688         list_create(&zilog->zl_lwb_list, sizeof (lwb_t),
1689             offsetof(lwb_t, lwb_node));
1690 
1691         list_create(&zilog->zl_itx_commit_list, sizeof (itx_t),
1692             offsetof(itx_t, itx_node));
1693 
1694         mutex_init(&zilog->zl_vdev_lock, NULL, MUTEX_DEFAULT, NULL);
1695 
1696         avl_create(&zilog->zl_vdev_tree, zil_vdev_compare,
1697             sizeof (zil_vdev_node_t), offsetof(zil_vdev_node_t, zv_node));
1698 
1699         cv_init(&zilog->zl_cv_writer, NULL, CV_DEFAULT, NULL);
1700         cv_init(&zilog->zl_cv_suspend, NULL, CV_DEFAULT, NULL);
1701         cv_init(&zilog->zl_cv_batch[0], NULL, CV_DEFAULT, NULL);
1702         cv_init(&zilog->zl_cv_batch[1], NULL, CV_DEFAULT, NULL);
1703 
1704         return (zilog);
1705 }
1706 
1707 void
1708 zil_free(zilog_t *zilog)
1709 {
1710         zilog->zl_stop_sync = 1;
1711 
1712         ASSERT0(zilog->zl_suspend);
1713         ASSERT0(zilog->zl_suspending);
1714 
1715         ASSERT(list_is_empty(&zilog->zl_lwb_list));
1716         list_destroy(&zilog->zl_lwb_list);
1717 
1718         avl_destroy(&zilog->zl_vdev_tree);
1719         mutex_destroy(&zilog->zl_vdev_lock);
1720 
1721         ASSERT(list_is_empty(&zilog->zl_itx_commit_list));
1722         list_destroy(&zilog->zl_itx_commit_list);
1723 
1724         for (int i = 0; i < TXG_SIZE; i++) {
1725                 /*
1726                  * It's possible for an itx to be generated that doesn't dirty
1727                  * a txg (e.g. ztest TX_TRUNCATE). So there's no zil_clean()
1728                  * callback to remove the entry. We remove those here.
1729                  *
1730                  * Also free up the ziltest itxs.
1731                  */
1732                 if (zilog->zl_itxg[i].itxg_itxs)
1733                         zil_itxg_clean(zilog->zl_itxg[i].itxg_itxs);
1734                 mutex_destroy(&zilog->zl_itxg[i].itxg_lock);
1735         }
1736 
1737         mutex_destroy(&zilog->zl_lock);
1738 
1739         cv_destroy(&zilog->zl_cv_writer);
1740         cv_destroy(&zilog->zl_cv_suspend);
1741         cv_destroy(&zilog->zl_cv_batch[0]);
1742         cv_destroy(&zilog->zl_cv_batch[1]);
1743 
1744         kmem_free(zilog, sizeof (zilog_t));
1745 }
1746 
1747 /*
1748  * Open an intent log.
1749  */
1750 zilog_t *
1751 zil_open(objset_t *os, zil_get_data_t *get_data)
1752 {
1753         zilog_t *zilog = dmu_objset_zil(os);
1754 
1755         ASSERT(zilog->zl_clean_taskq == NULL);
1756         ASSERT(zilog->zl_get_data == NULL);
1757         ASSERT(list_is_empty(&zilog->zl_lwb_list));
1758 
1759         zilog->zl_get_data = get_data;
1760         zilog->zl_clean_taskq = taskq_create("zil_clean", 1, minclsyspri,
1761             2, 2, TASKQ_PREPOPULATE);
1762 
1763         return (zilog);
1764 }
1765 
1766 /*
1767  * Close an intent log.
1768  */
1769 void
1770 zil_close(zilog_t *zilog)
1771 {
1772         lwb_t *lwb;
1773         uint64_t txg = 0;
1774 
1775         zil_commit(zilog, 0); /* commit all itx */
1776 
1777         /*
1778          * The lwb_max_txg for the stubby lwb will reflect the last activity
1779          * for the zil.  After a txg_wait_synced() on the txg we know all the
1780          * callbacks have occurred that may clean the zil.  Only then can we
1781          * destroy the zl_clean_taskq.
1782          */
1783         mutex_enter(&zilog->zl_lock);
1784         lwb = list_tail(&zilog->zl_lwb_list);
1785         if (lwb != NULL)
1786                 txg = lwb->lwb_max_txg;
1787         mutex_exit(&zilog->zl_lock);
1788         if (txg)
1789                 txg_wait_synced(zilog->zl_dmu_pool, txg);
1790         ASSERT(!zilog_is_dirty(zilog));
1791 
1792         taskq_destroy(zilog->zl_clean_taskq);
1793         zilog->zl_clean_taskq = NULL;
1794         zilog->zl_get_data = NULL;
1795 
1796         /*
1797          * We should have only one LWB left on the list; remove it now.
1798          */
1799         mutex_enter(&zilog->zl_lock);
1800         lwb = list_head(&zilog->zl_lwb_list);
1801         if (lwb != NULL) {
1802                 ASSERT(lwb == list_tail(&zilog->zl_lwb_list));
1803                 list_remove(&zilog->zl_lwb_list, lwb);
1804                 zio_buf_free(lwb->lwb_buf, lwb->lwb_sz);
1805                 kmem_cache_free(zil_lwb_cache, lwb);
1806         }
1807         mutex_exit(&zilog->zl_lock);
1808 }
1809 
1810 static char *suspend_tag = "zil suspending";
1811 
1812 /*
1813  * Suspend an intent log.  While in suspended mode, we still honor
1814  * synchronous semantics, but we rely on txg_wait_synced() to do it.
1815  * On old version pools, we suspend the log briefly when taking a
1816  * snapshot so that it will have an empty intent log.
1817  *
1818  * Long holds are not really intended to be used the way we do here --
1819  * held for such a short time.  A concurrent caller of dsl_dataset_long_held()
1820  * could fail.  Therefore we take pains to only put a long hold if it is
1821  * actually necessary.  Fortunately, it will only be necessary if the
1822  * objset is currently mounted (or the ZVOL equivalent).  In that case it
1823  * will already have a long hold, so we are not really making things any worse.
1824  *
1825  * Ideally, we would locate the existing long-holder (i.e. the zfsvfs_t or
1826  * zvol_state_t), and use their mechanism to prevent their hold from being
1827  * dropped (e.g. VFS_HOLD()).  However, that would be even more pain for
1828  * very little gain.
1829  *
1830  * if cookiep == NULL, this does both the suspend & resume.
1831  * Otherwise, it returns with the dataset "long held", and the cookie
1832  * should be passed into zil_resume().
1833  */
1834 int
1835 zil_suspend(const char *osname, void **cookiep)
1836 {
1837         objset_t *os;
1838         zilog_t *zilog;
1839         const zil_header_t *zh;
1840         int error;
1841 
1842         error = dmu_objset_hold(osname, suspend_tag, &os);
1843         if (error != 0)
1844                 return (error);
1845         zilog = dmu_objset_zil(os);
1846 
1847         mutex_enter(&zilog->zl_lock);
1848         zh = zilog->zl_header;
1849 
1850         if (zh->zh_flags & ZIL_REPLAY_NEEDED) {          /* unplayed log */
1851                 mutex_exit(&zilog->zl_lock);
1852                 dmu_objset_rele(os, suspend_tag);
1853                 return (SET_ERROR(EBUSY));
1854         }
1855 
1856         /*
1857          * Don't put a long hold in the cases where we can avoid it.  This
1858          * is when there is no cookie so we are doing a suspend & resume
1859          * (i.e. called from zil_vdev_offline()), and there's nothing to do
1860          * for the suspend because it's already suspended, or there's no ZIL.
1861          */
1862         if (cookiep == NULL && !zilog->zl_suspending &&
1863             (zilog->zl_suspend > 0 || BP_IS_HOLE(&zh->zh_log))) {
1864                 mutex_exit(&zilog->zl_lock);
1865                 dmu_objset_rele(os, suspend_tag);
1866                 return (0);
1867         }
1868 
1869         dsl_dataset_long_hold(dmu_objset_ds(os), suspend_tag);
1870         dsl_pool_rele(dmu_objset_pool(os), suspend_tag);
1871 
1872         zilog->zl_suspend++;
1873 
1874         if (zilog->zl_suspend > 1) {
1875                 /*
1876                  * Someone else is already suspending it.
1877                  * Just wait for them to finish.
1878                  */
1879 
1880                 while (zilog->zl_suspending)
1881                         cv_wait(&zilog->zl_cv_suspend, &zilog->zl_lock);
1882                 mutex_exit(&zilog->zl_lock);
1883 
1884                 if (cookiep == NULL)
1885                         zil_resume(os);
1886                 else
1887                         *cookiep = os;
1888                 return (0);
1889         }
1890 
1891         /*
1892          * If there is no pointer to an on-disk block, this ZIL must not
1893          * be active (e.g. filesystem not mounted), so there's nothing
1894          * to clean up.
1895          */
1896         if (BP_IS_HOLE(&zh->zh_log)) {
1897                 ASSERT(cookiep != NULL); /* fast path already handled */
1898 
1899                 *cookiep = os;
1900                 mutex_exit(&zilog->zl_lock);
1901                 return (0);
1902         }
1903 
1904         zilog->zl_suspending = B_TRUE;
1905         mutex_exit(&zilog->zl_lock);
1906 
1907         zil_commit(zilog, 0);
1908 
1909         zil_destroy(zilog, B_FALSE);
1910 
1911         mutex_enter(&zilog->zl_lock);
1912         zilog->zl_suspending = B_FALSE;
1913         cv_broadcast(&zilog->zl_cv_suspend);
1914         mutex_exit(&zilog->zl_lock);
1915 
1916         if (cookiep == NULL)
1917                 zil_resume(os);
1918         else
1919                 *cookiep = os;
1920         return (0);
1921 }
1922 
1923 void
1924 zil_resume(void *cookie)
1925 {
1926         objset_t *os = cookie;
1927         zilog_t *zilog = dmu_objset_zil(os);
1928 
1929         mutex_enter(&zilog->zl_lock);
1930         ASSERT(zilog->zl_suspend != 0);
1931         zilog->zl_suspend--;
1932         mutex_exit(&zilog->zl_lock);
1933         dsl_dataset_long_rele(dmu_objset_ds(os), suspend_tag);
1934         dsl_dataset_rele(dmu_objset_ds(os), suspend_tag);
1935 }
1936 
1937 typedef struct zil_replay_arg {
1938         zil_replay_func_t **zr_replay;
1939         void            *zr_arg;
1940         boolean_t       zr_byteswap;
1941         char            *zr_lr;
1942 } zil_replay_arg_t;
1943 
1944 static int
1945 zil_replay_error(zilog_t *zilog, lr_t *lr, int error)
1946 {
1947         char name[MAXNAMELEN];
1948 
1949         zilog->zl_replaying_seq--;   /* didn't actually replay this one */
1950 
1951         dmu_objset_name(zilog->zl_os, name);
1952 
1953         cmn_err(CE_WARN, "ZFS replay transaction error %d, "
1954             "dataset %s, seq 0x%llx, txtype %llu %s\n", error, name,
1955             (u_longlong_t)lr->lrc_seq,
1956             (u_longlong_t)(lr->lrc_txtype & ~TX_CI),
1957             (lr->lrc_txtype & TX_CI) ? "CI" : "");
1958 
1959         return (error);
1960 }
1961 
1962 static int
1963 zil_replay_log_record(zilog_t *zilog, lr_t *lr, void *zra, uint64_t claim_txg)
1964 {
1965         zil_replay_arg_t *zr = zra;
1966         const zil_header_t *zh = zilog->zl_header;
1967         uint64_t reclen = lr->lrc_reclen;
1968         uint64_t txtype = lr->lrc_txtype;
1969         int error = 0;
1970 
1971         zilog->zl_replaying_seq = lr->lrc_seq;
1972 
1973         if (lr->lrc_seq <= zh->zh_replay_seq)  /* already replayed */
1974                 return (0);
1975 
1976         if (lr->lrc_txg < claim_txg)              /* already committed */
1977                 return (0);
1978 
1979         /* Strip case-insensitive bit, still present in log record */
1980         txtype &= ~TX_CI;
1981 
1982         if (txtype == 0 || txtype >= TX_MAX_TYPE)
1983                 return (zil_replay_error(zilog, lr, EINVAL));
1984 
1985         /*
1986          * If this record type can be logged out of order, the object
1987          * (lr_foid) may no longer exist.  That's legitimate, not an error.
1988          */
1989         if (TX_OOO(txtype)) {
1990                 error = dmu_object_info(zilog->zl_os,
1991                     ((lr_ooo_t *)lr)->lr_foid, NULL);
1992                 if (error == ENOENT || error == EEXIST)
1993                         return (0);
1994         }
1995 
1996         /*
1997          * Make a copy of the data so we can revise and extend it.
1998          */
1999         bcopy(lr, zr->zr_lr, reclen);
2000 
2001         /*
2002          * If this is a TX_WRITE with a blkptr, suck in the data.
2003          */
2004         if (txtype == TX_WRITE && reclen == sizeof (lr_write_t)) {
2005                 error = zil_read_log_data(zilog, (lr_write_t *)lr,
2006                     zr->zr_lr + reclen);
2007                 if (error != 0)
2008                         return (zil_replay_error(zilog, lr, error));
2009         }
2010 
2011         /*
2012          * The log block containing this lr may have been byteswapped
2013          * so that we can easily examine common fields like lrc_txtype.
2014          * However, the log is a mix of different record types, and only the
2015          * replay vectors know how to byteswap their records.  Therefore, if
2016          * the lr was byteswapped, undo it before invoking the replay vector.
2017          */
2018         if (zr->zr_byteswap)
2019                 byteswap_uint64_array(zr->zr_lr, reclen);
2020 
2021         /*
2022          * We must now do two things atomically: replay this log record,
2023          * and update the log header sequence number to reflect the fact that
2024          * we did so. At the end of each replay function the sequence number
2025          * is updated if we are in replay mode.
2026          */
2027         error = zr->zr_replay[txtype](zr->zr_arg, zr->zr_lr, zr->zr_byteswap);
2028         if (error != 0) {
2029                 /*
2030                  * The DMU's dnode layer doesn't see removes until the txg
2031                  * commits, so a subsequent claim can spuriously fail with
2032                  * EEXIST. So if we receive any error we try syncing out
2033                  * any removes then retry the transaction.  Note that we
2034                  * specify B_FALSE for byteswap now, so we don't do it twice.
2035                  */
2036                 txg_wait_synced(spa_get_dsl(zilog->zl_spa), 0);
2037                 error = zr->zr_replay[txtype](zr->zr_arg, zr->zr_lr, B_FALSE);
2038                 if (error != 0)
2039                         return (zil_replay_error(zilog, lr, error));
2040         }
2041         return (0);
2042 }
2043 
2044 /* ARGSUSED */
2045 static int
2046 zil_incr_blks(zilog_t *zilog, blkptr_t *bp, void *arg, uint64_t claim_txg)
2047 {
2048         zilog->zl_replay_blks++;
2049 
2050         return (0);
2051 }
2052 
2053 /*
2054  * If this dataset has a non-empty intent log, replay it and destroy it.
2055  */
2056 void
2057 zil_replay(objset_t *os, void *arg, zil_replay_func_t *replay_func[TX_MAX_TYPE])
2058 {
2059         zilog_t *zilog = dmu_objset_zil(os);
2060         const zil_header_t *zh = zilog->zl_header;
2061         zil_replay_arg_t zr;
2062 
2063         if ((zh->zh_flags & ZIL_REPLAY_NEEDED) == 0) {
2064                 zil_destroy(zilog, B_TRUE);
2065                 return;
2066         }
2067 
2068         zr.zr_replay = replay_func;
2069         zr.zr_arg = arg;
2070         zr.zr_byteswap = BP_SHOULD_BYTESWAP(&zh->zh_log);
2071         zr.zr_lr = kmem_alloc(2 * SPA_MAXBLOCKSIZE, KM_SLEEP);
2072 
2073         /*
2074          * Wait for in-progress removes to sync before starting replay.
2075          */
2076         txg_wait_synced(zilog->zl_dmu_pool, 0);
2077 
2078         zilog->zl_replay = B_TRUE;
2079         zilog->zl_replay_time = ddi_get_lbolt();
2080         ASSERT(zilog->zl_replay_blks == 0);
2081         (void) zil_parse(zilog, zil_incr_blks, zil_replay_log_record, &zr,
2082             zh->zh_claim_txg);
2083         kmem_free(zr.zr_lr, 2 * SPA_MAXBLOCKSIZE);
2084 
2085         zil_destroy(zilog, B_FALSE);
2086         txg_wait_synced(zilog->zl_dmu_pool, zilog->zl_destroy_txg);
2087         zilog->zl_replay = B_FALSE;
2088 }
2089 
2090 boolean_t
2091 zil_replaying(zilog_t *zilog, dmu_tx_t *tx)
2092 {
2093         if (zilog->zl_sync == ZFS_SYNC_DISABLED)
2094                 return (B_TRUE);
2095 
2096         if (zilog->zl_replay) {
2097                 dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx);
2098                 zilog->zl_replayed_seq[dmu_tx_get_txg(tx) & TXG_MASK] =
2099                     zilog->zl_replaying_seq;
2100                 return (B_TRUE);
2101         }
2102 
2103         return (B_FALSE);
2104 }
2105 
2106 /* ARGSUSED */
2107 int
2108 zil_vdev_offline(const char *osname, void *arg)
2109 {
2110         int error;
2111 
2112         error = zil_suspend(osname, NULL);
2113         if (error != 0)
2114                 return (SET_ERROR(EEXIST));
2115         return (0);
2116 }