xfs_log_cil.c revision df806158b0f6eb24247773b4a19b8b59d7217e59
1/* 2 * Copyright (c) 2010 Red Hat, Inc. All Rights Reserved. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License as 6 * published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it would be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11 * GNU General Public License for more details. 12 * 13 * You should have received a copy of the GNU General Public License 14 * along with this program; if not, write the Free Software Foundation, 15 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 16 */ 17 18#include "xfs.h" 19#include "xfs_fs.h" 20#include "xfs_types.h" 21#include "xfs_bit.h" 22#include "xfs_log.h" 23#include "xfs_inum.h" 24#include "xfs_trans.h" 25#include "xfs_trans_priv.h" 26#include "xfs_log_priv.h" 27#include "xfs_sb.h" 28#include "xfs_ag.h" 29#include "xfs_dir2.h" 30#include "xfs_dmapi.h" 31#include "xfs_mount.h" 32#include "xfs_error.h" 33#include "xfs_alloc.h" 34 35/* 36 * Perform initial CIL structure initialisation. If the CIL is not 37 * enabled in this filesystem, ensure the log->l_cilp is null so 38 * we can check this conditional to determine if we are doing delayed 39 * logging or not. 40 */ 41int 42xlog_cil_init( 43 struct log *log) 44{ 45 struct xfs_cil *cil; 46 struct xfs_cil_ctx *ctx; 47 48 log->l_cilp = NULL; 49 if (!(log->l_mp->m_flags & XFS_MOUNT_DELAYLOG)) 50 return 0; 51 52 cil = kmem_zalloc(sizeof(*cil), KM_SLEEP|KM_MAYFAIL); 53 if (!cil) 54 return ENOMEM; 55 56 ctx = kmem_zalloc(sizeof(*ctx), KM_SLEEP|KM_MAYFAIL); 57 if (!ctx) { 58 kmem_free(cil); 59 return ENOMEM; 60 } 61 62 INIT_LIST_HEAD(&cil->xc_cil); 63 INIT_LIST_HEAD(&cil->xc_committing); 64 spin_lock_init(&cil->xc_cil_lock); 65 init_rwsem(&cil->xc_ctx_lock); 66 sv_init(&cil->xc_commit_wait, SV_DEFAULT, "cilwait"); 67 68 INIT_LIST_HEAD(&ctx->committing); 69 INIT_LIST_HEAD(&ctx->busy_extents); 70 ctx->sequence = 1; 71 ctx->cil = cil; 72 cil->xc_ctx = ctx; 73 74 cil->xc_log = log; 75 log->l_cilp = cil; 76 return 0; 77} 78 79void 80xlog_cil_destroy( 81 struct log *log) 82{ 83 if (!log->l_cilp) 84 return; 85 86 if (log->l_cilp->xc_ctx) { 87 if (log->l_cilp->xc_ctx->ticket) 88 xfs_log_ticket_put(log->l_cilp->xc_ctx->ticket); 89 kmem_free(log->l_cilp->xc_ctx); 90 } 91 92 ASSERT(list_empty(&log->l_cilp->xc_cil)); 93 kmem_free(log->l_cilp); 94} 95 96/* 97 * Allocate a new ticket. Failing to get a new ticket makes it really hard to 98 * recover, so we don't allow failure here. Also, we allocate in a context that 99 * we don't want to be issuing transactions from, so we need to tell the 100 * allocation code this as well. 101 * 102 * We don't reserve any space for the ticket - we are going to steal whatever 103 * space we require from transactions as they commit. To ensure we reserve all 104 * the space required, we need to set the current reservation of the ticket to 105 * zero so that we know to steal the initial transaction overhead from the 106 * first transaction commit. 107 */ 108static struct xlog_ticket * 109xlog_cil_ticket_alloc( 110 struct log *log) 111{ 112 struct xlog_ticket *tic; 113 114 tic = xlog_ticket_alloc(log, 0, 1, XFS_TRANSACTION, 0, 115 KM_SLEEP|KM_NOFS); 116 tic->t_trans_type = XFS_TRANS_CHECKPOINT; 117 118 /* 119 * set the current reservation to zero so we know to steal the basic 120 * transaction overhead reservation from the first transaction commit. 121 */ 122 tic->t_curr_res = 0; 123 return tic; 124} 125 126/* 127 * After the first stage of log recovery is done, we know where the head and 128 * tail of the log are. We need this log initialisation done before we can 129 * initialise the first CIL checkpoint context. 130 * 131 * Here we allocate a log ticket to track space usage during a CIL push. This 132 * ticket is passed to xlog_write() directly so that we don't slowly leak log 133 * space by failing to account for space used by log headers and additional 134 * region headers for split regions. 135 */ 136void 137xlog_cil_init_post_recovery( 138 struct log *log) 139{ 140 if (!log->l_cilp) 141 return; 142 143 log->l_cilp->xc_ctx->ticket = xlog_cil_ticket_alloc(log); 144 log->l_cilp->xc_ctx->sequence = 1; 145 log->l_cilp->xc_ctx->commit_lsn = xlog_assign_lsn(log->l_curr_cycle, 146 log->l_curr_block); 147} 148 149/* 150 * Insert the log item into the CIL and calculate the difference in space 151 * consumed by the item. Add the space to the checkpoint ticket and calculate 152 * if the change requires additional log metadata. If it does, take that space 153 * as well. Remove the amount of space we addded to the checkpoint ticket from 154 * the current transaction ticket so that the accounting works out correctly. 155 * 156 * If this is the first time the item is being placed into the CIL in this 157 * context, pin it so it can't be written to disk until the CIL is flushed to 158 * the iclog and the iclog written to disk. 159 */ 160static void 161xlog_cil_insert( 162 struct log *log, 163 struct xlog_ticket *ticket, 164 struct xfs_log_item *item, 165 struct xfs_log_vec *lv) 166{ 167 struct xfs_cil *cil = log->l_cilp; 168 struct xfs_log_vec *old = lv->lv_item->li_lv; 169 struct xfs_cil_ctx *ctx = cil->xc_ctx; 170 int len; 171 int diff_iovecs; 172 int iclog_space; 173 174 if (old) { 175 /* existing lv on log item, space used is a delta */ 176 ASSERT(!list_empty(&item->li_cil)); 177 ASSERT(old->lv_buf && old->lv_buf_len && old->lv_niovecs); 178 179 len = lv->lv_buf_len - old->lv_buf_len; 180 diff_iovecs = lv->lv_niovecs - old->lv_niovecs; 181 kmem_free(old->lv_buf); 182 kmem_free(old); 183 } else { 184 /* new lv, must pin the log item */ 185 ASSERT(!lv->lv_item->li_lv); 186 ASSERT(list_empty(&item->li_cil)); 187 188 len = lv->lv_buf_len; 189 diff_iovecs = lv->lv_niovecs; 190 IOP_PIN(lv->lv_item); 191 192 } 193 len += diff_iovecs * sizeof(xlog_op_header_t); 194 195 /* attach new log vector to log item */ 196 lv->lv_item->li_lv = lv; 197 198 spin_lock(&cil->xc_cil_lock); 199 list_move_tail(&item->li_cil, &cil->xc_cil); 200 ctx->nvecs += diff_iovecs; 201 202 /* 203 * Now transfer enough transaction reservation to the context ticket 204 * for the checkpoint. The context ticket is special - the unit 205 * reservation has to grow as well as the current reservation as we 206 * steal from tickets so we can correctly determine the space used 207 * during the transaction commit. 208 */ 209 if (ctx->ticket->t_curr_res == 0) { 210 /* first commit in checkpoint, steal the header reservation */ 211 ASSERT(ticket->t_curr_res >= ctx->ticket->t_unit_res + len); 212 ctx->ticket->t_curr_res = ctx->ticket->t_unit_res; 213 ticket->t_curr_res -= ctx->ticket->t_unit_res; 214 } 215 216 /* do we need space for more log record headers? */ 217 iclog_space = log->l_iclog_size - log->l_iclog_hsize; 218 if (len > 0 && (ctx->space_used / iclog_space != 219 (ctx->space_used + len) / iclog_space)) { 220 int hdrs; 221 222 hdrs = (len + iclog_space - 1) / iclog_space; 223 /* need to take into account split region headers, too */ 224 hdrs *= log->l_iclog_hsize + sizeof(struct xlog_op_header); 225 ctx->ticket->t_unit_res += hdrs; 226 ctx->ticket->t_curr_res += hdrs; 227 ticket->t_curr_res -= hdrs; 228 ASSERT(ticket->t_curr_res >= len); 229 } 230 ticket->t_curr_res -= len; 231 ctx->space_used += len; 232 233 spin_unlock(&cil->xc_cil_lock); 234} 235 236/* 237 * Format log item into a flat buffers 238 * 239 * For delayed logging, we need to hold a formatted buffer containing all the 240 * changes on the log item. This enables us to relog the item in memory and 241 * write it out asynchronously without needing to relock the object that was 242 * modified at the time it gets written into the iclog. 243 * 244 * This function builds a vector for the changes in each log item in the 245 * transaction. It then works out the length of the buffer needed for each log 246 * item, allocates them and formats the vector for the item into the buffer. 247 * The buffer is then attached to the log item are then inserted into the 248 * Committed Item List for tracking until the next checkpoint is written out. 249 * 250 * We don't set up region headers during this process; we simply copy the 251 * regions into the flat buffer. We can do this because we still have to do a 252 * formatting step to write the regions into the iclog buffer. Writing the 253 * ophdrs during the iclog write means that we can support splitting large 254 * regions across iclog boundares without needing a change in the format of the 255 * item/region encapsulation. 256 * 257 * Hence what we need to do now is change the rewrite the vector array to point 258 * to the copied region inside the buffer we just allocated. This allows us to 259 * format the regions into the iclog as though they are being formatted 260 * directly out of the objects themselves. 261 */ 262static void 263xlog_cil_format_items( 264 struct log *log, 265 struct xfs_log_vec *log_vector, 266 struct xlog_ticket *ticket, 267 xfs_lsn_t *start_lsn) 268{ 269 struct xfs_log_vec *lv; 270 271 if (start_lsn) 272 *start_lsn = log->l_cilp->xc_ctx->sequence; 273 274 ASSERT(log_vector); 275 for (lv = log_vector; lv; lv = lv->lv_next) { 276 void *ptr; 277 int index; 278 int len = 0; 279 280 /* build the vector array and calculate it's length */ 281 IOP_FORMAT(lv->lv_item, lv->lv_iovecp); 282 for (index = 0; index < lv->lv_niovecs; index++) 283 len += lv->lv_iovecp[index].i_len; 284 285 lv->lv_buf_len = len; 286 lv->lv_buf = kmem_zalloc(lv->lv_buf_len, KM_SLEEP|KM_NOFS); 287 ptr = lv->lv_buf; 288 289 for (index = 0; index < lv->lv_niovecs; index++) { 290 struct xfs_log_iovec *vec = &lv->lv_iovecp[index]; 291 292 memcpy(ptr, vec->i_addr, vec->i_len); 293 vec->i_addr = ptr; 294 ptr += vec->i_len; 295 } 296 ASSERT(ptr == lv->lv_buf + lv->lv_buf_len); 297 298 xlog_cil_insert(log, ticket, lv->lv_item, lv); 299 } 300} 301 302static void 303xlog_cil_free_logvec( 304 struct xfs_log_vec *log_vector) 305{ 306 struct xfs_log_vec *lv; 307 308 for (lv = log_vector; lv; ) { 309 struct xfs_log_vec *next = lv->lv_next; 310 kmem_free(lv->lv_buf); 311 kmem_free(lv); 312 lv = next; 313 } 314} 315 316/* 317 * Commit a transaction with the given vector to the Committed Item List. 318 * 319 * To do this, we need to format the item, pin it in memory if required and 320 * account for the space used by the transaction. Once we have done that we 321 * need to release the unused reservation for the transaction, attach the 322 * transaction to the checkpoint context so we carry the busy extents through 323 * to checkpoint completion, and then unlock all the items in the transaction. 324 * 325 * For more specific information about the order of operations in 326 * xfs_log_commit_cil() please refer to the comments in 327 * xfs_trans_commit_iclog(). 328 */ 329int 330xfs_log_commit_cil( 331 struct xfs_mount *mp, 332 struct xfs_trans *tp, 333 struct xfs_log_vec *log_vector, 334 xfs_lsn_t *commit_lsn, 335 int flags) 336{ 337 struct log *log = mp->m_log; 338 int log_flags = 0; 339 int push = 0; 340 341 if (flags & XFS_TRANS_RELEASE_LOG_RES) 342 log_flags = XFS_LOG_REL_PERM_RESERV; 343 344 if (XLOG_FORCED_SHUTDOWN(log)) { 345 xlog_cil_free_logvec(log_vector); 346 return XFS_ERROR(EIO); 347 } 348 349 /* lock out background commit */ 350 down_read(&log->l_cilp->xc_ctx_lock); 351 xlog_cil_format_items(log, log_vector, tp->t_ticket, commit_lsn); 352 353 /* check we didn't blow the reservation */ 354 if (tp->t_ticket->t_curr_res < 0) 355 xlog_print_tic_res(log->l_mp, tp->t_ticket); 356 357 /* attach the transaction to the CIL if it has any busy extents */ 358 if (!list_empty(&tp->t_busy)) { 359 spin_lock(&log->l_cilp->xc_cil_lock); 360 list_splice_init(&tp->t_busy, 361 &log->l_cilp->xc_ctx->busy_extents); 362 spin_unlock(&log->l_cilp->xc_cil_lock); 363 } 364 365 tp->t_commit_lsn = *commit_lsn; 366 xfs_log_done(mp, tp->t_ticket, NULL, log_flags); 367 xfs_trans_unreserve_and_mod_sb(tp); 368 369 /* check for background commit before unlock */ 370 if (log->l_cilp->xc_ctx->space_used > XLOG_CIL_SPACE_LIMIT(log)) 371 push = 1; 372 up_read(&log->l_cilp->xc_ctx_lock); 373 374 /* 375 * We need to push CIL every so often so we don't cache more than we 376 * can fit in the log. The limit really is that a checkpoint can't be 377 * more than half the log (the current checkpoint is not allowed to 378 * overwrite the previous checkpoint), but commit latency and memory 379 * usage limit this to a smaller size in most cases. 380 */ 381 if (push) 382 xlog_cil_push(log, 0); 383 return 0; 384} 385 386/* 387 * Mark all items committed and clear busy extents. We free the log vector 388 * chains in a separate pass so that we unpin the log items as quickly as 389 * possible. 390 */ 391static void 392xlog_cil_committed( 393 void *args, 394 int abort) 395{ 396 struct xfs_cil_ctx *ctx = args; 397 struct xfs_log_vec *lv; 398 int abortflag = abort ? XFS_LI_ABORTED : 0; 399 struct xfs_busy_extent *busyp, *n; 400 401 /* unpin all the log items */ 402 for (lv = ctx->lv_chain; lv; lv = lv->lv_next ) { 403 xfs_trans_item_committed(lv->lv_item, ctx->start_lsn, 404 abortflag); 405 } 406 407 list_for_each_entry_safe(busyp, n, &ctx->busy_extents, list) 408 xfs_alloc_busy_clear(ctx->cil->xc_log->l_mp, busyp); 409 410 spin_lock(&ctx->cil->xc_cil_lock); 411 list_del(&ctx->committing); 412 spin_unlock(&ctx->cil->xc_cil_lock); 413 414 xlog_cil_free_logvec(ctx->lv_chain); 415 kmem_free(ctx); 416} 417 418/* 419 * Push the Committed Item List to the log. If the push_now flag is not set, 420 * then it is a background flush and so we can chose to ignore it. 421 */ 422int 423xlog_cil_push( 424 struct log *log, 425 int push_now) 426{ 427 struct xfs_cil *cil = log->l_cilp; 428 struct xfs_log_vec *lv; 429 struct xfs_cil_ctx *ctx; 430 struct xfs_cil_ctx *new_ctx; 431 struct xlog_in_core *commit_iclog; 432 struct xlog_ticket *tic; 433 int num_lv; 434 int num_iovecs; 435 int len; 436 int error = 0; 437 struct xfs_trans_header thdr; 438 struct xfs_log_iovec lhdr; 439 struct xfs_log_vec lvhdr = { NULL }; 440 xfs_lsn_t commit_lsn; 441 442 if (!cil) 443 return 0; 444 445 new_ctx = kmem_zalloc(sizeof(*new_ctx), KM_SLEEP|KM_NOFS); 446 new_ctx->ticket = xlog_cil_ticket_alloc(log); 447 448 /* lock out transaction commit, but don't block on background push */ 449 if (!down_write_trylock(&cil->xc_ctx_lock)) { 450 if (!push_now) 451 goto out_free_ticket; 452 down_write(&cil->xc_ctx_lock); 453 } 454 ctx = cil->xc_ctx; 455 456 /* check if we've anything to push */ 457 if (list_empty(&cil->xc_cil)) 458 goto out_skip; 459 460 /* check for spurious background flush */ 461 if (!push_now && cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log)) 462 goto out_skip; 463 464 /* 465 * pull all the log vectors off the items in the CIL, and 466 * remove the items from the CIL. We don't need the CIL lock 467 * here because it's only needed on the transaction commit 468 * side which is currently locked out by the flush lock. 469 */ 470 lv = NULL; 471 num_lv = 0; 472 num_iovecs = 0; 473 len = 0; 474 while (!list_empty(&cil->xc_cil)) { 475 struct xfs_log_item *item; 476 int i; 477 478 item = list_first_entry(&cil->xc_cil, 479 struct xfs_log_item, li_cil); 480 list_del_init(&item->li_cil); 481 if (!ctx->lv_chain) 482 ctx->lv_chain = item->li_lv; 483 else 484 lv->lv_next = item->li_lv; 485 lv = item->li_lv; 486 item->li_lv = NULL; 487 488 num_lv++; 489 num_iovecs += lv->lv_niovecs; 490 for (i = 0; i < lv->lv_niovecs; i++) 491 len += lv->lv_iovecp[i].i_len; 492 } 493 494 /* 495 * initialise the new context and attach it to the CIL. Then attach 496 * the current context to the CIL committing lsit so it can be found 497 * during log forces to extract the commit lsn of the sequence that 498 * needs to be forced. 499 */ 500 INIT_LIST_HEAD(&new_ctx->committing); 501 INIT_LIST_HEAD(&new_ctx->busy_extents); 502 new_ctx->sequence = ctx->sequence + 1; 503 new_ctx->cil = cil; 504 cil->xc_ctx = new_ctx; 505 506 /* 507 * The switch is now done, so we can drop the context lock and move out 508 * of a shared context. We can't just go straight to the commit record, 509 * though - we need to synchronise with previous and future commits so 510 * that the commit records are correctly ordered in the log to ensure 511 * that we process items during log IO completion in the correct order. 512 * 513 * For example, if we get an EFI in one checkpoint and the EFD in the 514 * next (e.g. due to log forces), we do not want the checkpoint with 515 * the EFD to be committed before the checkpoint with the EFI. Hence 516 * we must strictly order the commit records of the checkpoints so 517 * that: a) the checkpoint callbacks are attached to the iclogs in the 518 * correct order; and b) the checkpoints are replayed in correct order 519 * in log recovery. 520 * 521 * Hence we need to add this context to the committing context list so 522 * that higher sequences will wait for us to write out a commit record 523 * before they do. 524 */ 525 spin_lock(&cil->xc_cil_lock); 526 list_add(&ctx->committing, &cil->xc_committing); 527 spin_unlock(&cil->xc_cil_lock); 528 up_write(&cil->xc_ctx_lock); 529 530 /* 531 * Build a checkpoint transaction header and write it to the log to 532 * begin the transaction. We need to account for the space used by the 533 * transaction header here as it is not accounted for in xlog_write(). 534 * 535 * The LSN we need to pass to the log items on transaction commit is 536 * the LSN reported by the first log vector write. If we use the commit 537 * record lsn then we can move the tail beyond the grant write head. 538 */ 539 tic = ctx->ticket; 540 thdr.th_magic = XFS_TRANS_HEADER_MAGIC; 541 thdr.th_type = XFS_TRANS_CHECKPOINT; 542 thdr.th_tid = tic->t_tid; 543 thdr.th_num_items = num_iovecs; 544 lhdr.i_addr = (xfs_caddr_t)&thdr; 545 lhdr.i_len = sizeof(xfs_trans_header_t); 546 lhdr.i_type = XLOG_REG_TYPE_TRANSHDR; 547 tic->t_curr_res -= lhdr.i_len + sizeof(xlog_op_header_t); 548 549 lvhdr.lv_niovecs = 1; 550 lvhdr.lv_iovecp = &lhdr; 551 lvhdr.lv_next = ctx->lv_chain; 552 553 error = xlog_write(log, &lvhdr, tic, &ctx->start_lsn, NULL, 0); 554 if (error) 555 goto out_abort; 556 557 /* 558 * now that we've written the checkpoint into the log, strictly 559 * order the commit records so replay will get them in the right order. 560 */ 561restart: 562 spin_lock(&cil->xc_cil_lock); 563 list_for_each_entry(new_ctx, &cil->xc_committing, committing) { 564 /* 565 * Higher sequences will wait for this one so skip them. 566 * Don't wait for own own sequence, either. 567 */ 568 if (new_ctx->sequence >= ctx->sequence) 569 continue; 570 if (!new_ctx->commit_lsn) { 571 /* 572 * It is still being pushed! Wait for the push to 573 * complete, then start again from the beginning. 574 */ 575 sv_wait(&cil->xc_commit_wait, 0, &cil->xc_cil_lock, 0); 576 goto restart; 577 } 578 } 579 spin_unlock(&cil->xc_cil_lock); 580 581 commit_lsn = xfs_log_done(log->l_mp, tic, &commit_iclog, 0); 582 if (error || commit_lsn == -1) 583 goto out_abort; 584 585 /* attach all the transactions w/ busy extents to iclog */ 586 ctx->log_cb.cb_func = xlog_cil_committed; 587 ctx->log_cb.cb_arg = ctx; 588 error = xfs_log_notify(log->l_mp, commit_iclog, &ctx->log_cb); 589 if (error) 590 goto out_abort; 591 592 /* 593 * now the checkpoint commit is complete and we've attached the 594 * callbacks to the iclog we can assign the commit LSN to the context 595 * and wake up anyone who is waiting for the commit to complete. 596 */ 597 spin_lock(&cil->xc_cil_lock); 598 ctx->commit_lsn = commit_lsn; 599 sv_broadcast(&cil->xc_commit_wait); 600 spin_unlock(&cil->xc_cil_lock); 601 602 /* release the hounds! */ 603 return xfs_log_release_iclog(log->l_mp, commit_iclog); 604 605out_skip: 606 up_write(&cil->xc_ctx_lock); 607out_free_ticket: 608 xfs_log_ticket_put(new_ctx->ticket); 609 kmem_free(new_ctx); 610 return 0; 611 612out_abort: 613 xlog_cil_committed(ctx, XFS_LI_ABORTED); 614 return XFS_ERROR(EIO); 615} 616 617/* 618 * Conditionally push the CIL based on the sequence passed in. 619 * 620 * We only need to push if we haven't already pushed the sequence 621 * number given. Hence the only time we will trigger a push here is 622 * if the push sequence is the same as the current context. 623 * 624 * We return the current commit lsn to allow the callers to determine if a 625 * iclog flush is necessary following this call. 626 * 627 * XXX: Initially, just push the CIL unconditionally and return whatever 628 * commit lsn is there. It'll be empty, so this is broken for now. 629 */ 630xfs_lsn_t 631xlog_cil_push_lsn( 632 struct log *log, 633 xfs_lsn_t push_seq) 634{ 635 struct xfs_cil *cil = log->l_cilp; 636 struct xfs_cil_ctx *ctx; 637 xfs_lsn_t commit_lsn = NULLCOMMITLSN; 638 639restart: 640 down_write(&cil->xc_ctx_lock); 641 ASSERT(push_seq <= cil->xc_ctx->sequence); 642 643 /* check to see if we need to force out the current context */ 644 if (push_seq == cil->xc_ctx->sequence) { 645 up_write(&cil->xc_ctx_lock); 646 xlog_cil_push(log, 1); 647 goto restart; 648 } 649 650 /* 651 * See if we can find a previous sequence still committing. 652 * We can drop the flush lock as soon as we have the cil lock 653 * because we are now only comparing contexts protected by 654 * the cil lock. 655 * 656 * We need to wait for all previous sequence commits to complete 657 * before allowing the force of push_seq to go ahead. Hence block 658 * on commits for those as well. 659 */ 660 spin_lock(&cil->xc_cil_lock); 661 up_write(&cil->xc_ctx_lock); 662 list_for_each_entry(ctx, &cil->xc_committing, committing) { 663 if (ctx->sequence > push_seq) 664 continue; 665 if (!ctx->commit_lsn) { 666 /* 667 * It is still being pushed! Wait for the push to 668 * complete, then start again from the beginning. 669 */ 670 sv_wait(&cil->xc_commit_wait, 0, &cil->xc_cil_lock, 0); 671 goto restart; 672 } 673 if (ctx->sequence != push_seq) 674 continue; 675 /* found it! */ 676 commit_lsn = ctx->commit_lsn; 677 } 678 spin_unlock(&cil->xc_cil_lock); 679 return commit_lsn; 680} 681