User: | Jiri Slaby |
Error type: | Double Lock |
Error type description: | Some lock is locked twice unintentionally in a sequence |
File location: | fs/jbd/commit.c |
Line in file: | 463 |
Project: | Linux Kernel |
Project version: | 2.6.28 |
Tools: |
Stanse
(1.2)
Smatch (1.59) |
Entered: | 2011-11-07 22:19:59 UTC |
1/* 2 * linux/fs/jbd/commit.c 3 * 4 * Written by Stephen C. Tweedie <sct@redhat.com>, 1998 5 * 6 * Copyright 1998 Red Hat corp --- All Rights Reserved 7 * 8 * This file is part of the Linux kernel and is made available under 9 * the terms of the GNU General Public License, version 2, or at your 10 * option, any later version, incorporated herein by reference. 11 * 12 * Journal commit routines for the generic filesystem journaling code; 13 * part of the ext2fs journaling system. 14 */ 15 16#include <linux/time.h> 17#include <linux/fs.h> 18#include <linux/jbd.h> 19#include <linux/errno.h> 20#include <linux/slab.h> 21#include <linux/mm.h> 22#include <linux/pagemap.h> 23 24/* 25 * Default IO end handler for temporary BJ_IO buffer_heads. 26 */ 27static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate) 28{ 29 BUFFER_TRACE(bh, ""); 30 if (uptodate) 31 set_buffer_uptodate(bh); 32 else 33 clear_buffer_uptodate(bh); 34 unlock_buffer(bh); 35} 36 37/* 38 * When an ext3-ordered file is truncated, it is possible that many pages are 39 * not successfully freed, because they are attached to a committing transaction. 40 * After the transaction commits, these pages are left on the LRU, with no 41 * ->mapping, and with attached buffers. These pages are trivially reclaimable 42 * by the VM, but their apparent absence upsets the VM accounting, and it makes 43 * the numbers in /proc/meminfo look odd. 44 * 45 * So here, we have a buffer which has just come off the forget list. Look to 46 * see if we can strip all buffers from the backing page. 47 * 48 * Called under journal->j_list_lock. The caller provided us with a ref 49 * against the buffer, and we drop that here. 50 */ 51static void release_buffer_page(struct buffer_head *bh) 52{ 53 struct page *page; 54 55 if (buffer_dirty(bh)) 56 goto nope; 57 if (atomic_read(&bh->b_count) != 1) 58 goto nope; 59 page = bh->b_page; 60 if (!page) 61 goto nope; 62 if (page->mapping) 63 goto nope; 64 65 /* OK, it's a truncated page */ 66 if (!trylock_page(page)) 67 goto nope; 68 69 page_cache_get(page); 70 __brelse(bh); 71 try_to_free_buffers(page); 72 unlock_page(page); 73 page_cache_release(page); 74 return; 75 76nope: 77 __brelse(bh); 78} 79 80/* 81 * Decrement reference counter for data buffer. If it has been marked 82 * 'BH_Freed', release it and the page to which it belongs if possible. 83 */ 84static void release_data_buffer(struct buffer_head *bh) 85{ 86 if (buffer_freed(bh)) { 87 clear_buffer_freed(bh); 88 release_buffer_page(bh); 89 } else 90 put_bh(bh); 91} 92 93/* 94 * Try to acquire jbd_lock_bh_state() against the buffer, when j_list_lock is 95 * held. For ranking reasons we must trylock. If we lose, schedule away and 96 * return 0. j_list_lock is dropped in this case. 97 */ 98static int inverted_lock(journal_t *journal, struct buffer_head *bh) 99{ 100 if (!jbd_trylock_bh_state(bh)) { 101 spin_unlock(&journal->j_list_lock); 102 schedule(); 103 return 0; 104 } 105 return 1; 106} 107 108/* Done it all: now write the commit record. We should have 109 * cleaned up our previous buffers by now, so if we are in abort 110 * mode we can now just skip the rest of the journal write 111 * entirely. 112 * 113 * Returns 1 if the journal needs to be aborted or 0 on success 114 */ 115static int journal_write_commit_record(journal_t *journal, 116 transaction_t *commit_transaction) 117{ 118 struct journal_head *descriptor; 119 struct buffer_head *bh; 120 journal_header_t *header; 121 int ret; 122 int barrier_done = 0; 123 124 if (is_journal_aborted(journal)) 125 return 0; 126 127 descriptor = journal_get_descriptor_buffer(journal); 128 if (!descriptor) 129 return 1; 130 131 bh = jh2bh(descriptor); 132 133 header = (journal_header_t *)(bh->b_data); 134 header->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER); 135 header->h_blocktype = cpu_to_be32(JFS_COMMIT_BLOCK); 136 header->h_sequence = cpu_to_be32(commit_transaction->t_tid); 137 138 JBUFFER_TRACE(descriptor, "write commit block"); 139 set_buffer_dirty(bh); 140 if (journal->j_flags & JFS_BARRIER) { 141 set_buffer_ordered(bh); 142 barrier_done = 1; 143 } 144 ret = sync_dirty_buffer(bh); 145 if (barrier_done) 146 clear_buffer_ordered(bh); 147 /* is it possible for another commit to fail at roughly 148 * the same time as this one? If so, we don't want to 149 * trust the barrier flag in the super, but instead want 150 * to remember if we sent a barrier request 151 */ 152 if (ret == -EOPNOTSUPP && barrier_done) { 153 char b[BDEVNAME_SIZE]; 154 155 printk(KERN_WARNING 156 "JBD: barrier-based sync failed on %s - " 157 "disabling barriers\n", 158 bdevname(journal->j_dev, b)); 159 spin_lock(&journal->j_state_lock); 160 journal->j_flags &= ~JFS_BARRIER; 161 spin_unlock(&journal->j_state_lock); 162 163 /* And try again, without the barrier */ 164 set_buffer_uptodate(bh); 165 set_buffer_dirty(bh); 166 ret = sync_dirty_buffer(bh); 167 } 168 put_bh(bh); /* One for getblk() */ 169 journal_put_journal_head(descriptor); 170 171 return (ret == -EIO); 172} 173 174static void journal_do_submit_data(struct buffer_head **wbuf, int bufs) 175{ 176 int i; 177 178 for (i = 0; i < bufs; i++) { 179 wbuf[i]->b_end_io = end_buffer_write_sync; 180 /* We use-up our safety reference in submit_bh() */ 181 submit_bh(WRITE, wbuf[i]); 182 } 183} 184 185/* 186 * Submit all the data buffers to disk 187 */ 188static int journal_submit_data_buffers(journal_t *journal, 189 transaction_t *commit_transaction) 190{ 191 struct journal_head *jh; 192 struct buffer_head *bh; 193 int locked; 194 int bufs = 0; 195 struct buffer_head **wbuf = journal->j_wbuf; 196 int err = 0; 197 198 /* 199 * Whenever we unlock the journal and sleep, things can get added 200 * onto ->t_sync_datalist, so we have to keep looping back to 201 * write_out_data until we *know* that the list is empty. 202 * 203 * Cleanup any flushed data buffers from the data list. Even in 204 * abort mode, we want to flush this out as soon as possible. 205 */ 206write_out_data: 207 cond_resched(); 208 spin_lock(&journal->j_list_lock); 209 210 while (commit_transaction->t_sync_datalist) { 211 jh = commit_transaction->t_sync_datalist; 212 bh = jh2bh(jh); 213 locked = 0; 214 215 /* Get reference just to make sure buffer does not disappear 216 * when we are forced to drop various locks */ 217 get_bh(bh); 218 /* If the buffer is dirty, we need to submit IO and hence 219 * we need the buffer lock. We try to lock the buffer without 220 * blocking. If we fail, we need to drop j_list_lock and do 221 * blocking lock_buffer(). 222 */ 223 if (buffer_dirty(bh)) { 224 if (!trylock_buffer(bh)) { 225 BUFFER_TRACE(bh, "needs blocking lock"); 226 spin_unlock(&journal->j_list_lock); 227 /* Write out all data to prevent deadlocks */ 228 journal_do_submit_data(wbuf, bufs); 229 bufs = 0; 230 lock_buffer(bh); 231 spin_lock(&journal->j_list_lock); 232 } 233 locked = 1; 234 } 235 /* We have to get bh_state lock. Again out of order, sigh. */ 236 if (!inverted_lock(journal, bh)) { 237 jbd_lock_bh_state(bh); 238 spin_lock(&journal->j_list_lock); 239 } 240 /* Someone already cleaned up the buffer? */ 241 if (!buffer_jbd(bh) 242 || jh->b_transaction != commit_transaction 243 || jh->b_jlist != BJ_SyncData) { 244 jbd_unlock_bh_state(bh); 245 if (locked) 246 unlock_buffer(bh); 247 BUFFER_TRACE(bh, "already cleaned up"); 248 release_data_buffer(bh); 249 continue; 250 } 251 if (locked && test_clear_buffer_dirty(bh)) { 252 BUFFER_TRACE(bh, "needs writeout, adding to array"); 253 wbuf[bufs++] = bh; 254 __journal_file_buffer(jh, commit_transaction, 255 BJ_Locked); 256 jbd_unlock_bh_state(bh); 257 if (bufs == journal->j_wbufsize) { 258 spin_unlock(&journal->j_list_lock); 259 journal_do_submit_data(wbuf, bufs); 260 bufs = 0; 261 goto write_out_data; 262 } 263 } else if (!locked && buffer_locked(bh)) { 264 __journal_file_buffer(jh, commit_transaction, 265 BJ_Locked); 266 jbd_unlock_bh_state(bh); 267 put_bh(bh); 268 } else { 269 BUFFER_TRACE(bh, "writeout complete: unfile"); 270 if (unlikely(!buffer_uptodate(bh))) 271 err = -EIO; 272 __journal_unfile_buffer(jh); 273 jbd_unlock_bh_state(bh); 274 if (locked) 275 unlock_buffer(bh); 276 journal_remove_journal_head(bh); 277 /* One for our safety reference, other for 278 * journal_remove_journal_head() */ 279 put_bh(bh); 280 release_data_buffer(bh); 281 } 282 283 if (need_resched() || spin_needbreak(&journal->j_list_lock)) { 284 spin_unlock(&journal->j_list_lock); 285 goto write_out_data; 286 } 287 } 288 spin_unlock(&journal->j_list_lock); 289 journal_do_submit_data(wbuf, bufs); 290 291 return err; 292} 293 294/* 295 * journal_commit_transaction 296 * 297 * The primary function for committing a transaction to the log. This 298 * function is called by the journal thread to begin a complete commit. 299 */ 300void journal_commit_transaction(journal_t *journal) 301{ 302 transaction_t *commit_transaction; 303 struct journal_head *jh, *new_jh, *descriptor; 304 struct buffer_head **wbuf = journal->j_wbuf; 305 int bufs; 306 int flags; 307 int err; 308 unsigned long blocknr; 309 char *tagp = NULL; 310 journal_header_t *header; 311 journal_block_tag_t *tag = NULL; 312 int space_left = 0; 313 int first_tag = 0; 314 int tag_flag; 315 int i; 316 317 /* 318 * First job: lock down the current transaction and wait for 319 * all outstanding updates to complete. 320 */ 321 322#ifdef COMMIT_STATS 323 spin_lock(&journal->j_list_lock); 324 summarise_journal_usage(journal); 325 spin_unlock(&journal->j_list_lock); 326#endif 327 328 /* Do we need to erase the effects of a prior journal_flush? */ 329 if (journal->j_flags & JFS_FLUSHED) { 330 jbd_debug(3, "super block updated\n"); 331 journal_update_superblock(journal, 1); 332 } else { 333 jbd_debug(3, "superblock not updated\n"); 334 } 335 336 J_ASSERT(journal->j_running_transaction != NULL); 337 J_ASSERT(journal->j_committing_transaction == NULL); 338 339 commit_transaction = journal->j_running_transaction; 340 J_ASSERT(commit_transaction->t_state == T_RUNNING); 341 342 jbd_debug(1, "JBD: starting commit of transaction %d\n", 343 commit_transaction->t_tid); 344 345 spin_lock(&journal->j_state_lock); 346 commit_transaction->t_state = T_LOCKED; 347 348 spin_lock(&commit_transaction->t_handle_lock); 349 while (commit_transaction->t_updates) { 350 DEFINE_WAIT(wait); 351 352 prepare_to_wait(&journal->j_wait_updates, &wait, 353 TASK_UNINTERRUPTIBLE); 354 if (commit_transaction->t_updates) { 355 spin_unlock(&commit_transaction->t_handle_lock); 356 spin_unlock(&journal->j_state_lock); 357 schedule(); 358 spin_lock(&journal->j_state_lock); 359 spin_lock(&commit_transaction->t_handle_lock); 360 } 361 finish_wait(&journal->j_wait_updates, &wait); 362 } 363 spin_unlock(&commit_transaction->t_handle_lock); 364 365 J_ASSERT (commit_transaction->t_outstanding_credits <= 366 journal->j_max_transaction_buffers); 367 368 /* 369 * First thing we are allowed to do is to discard any remaining 370 * BJ_Reserved buffers. Note, it is _not_ permissible to assume 371 * that there are no such buffers: if a large filesystem 372 * operation like a truncate needs to split itself over multiple 373 * transactions, then it may try to do a journal_restart() while 374 * there are still BJ_Reserved buffers outstanding. These must 375 * be released cleanly from the current transaction. 376 * 377 * In this case, the filesystem must still reserve write access 378 * again before modifying the buffer in the new transaction, but 379 * we do not require it to remember exactly which old buffers it 380 * has reserved. This is consistent with the existing behaviour 381 * that multiple journal_get_write_access() calls to the same 382 * buffer are perfectly permissable. 383 */ 384 while (commit_transaction->t_reserved_list) { 385 jh = commit_transaction->t_reserved_list; 386 JBUFFER_TRACE(jh, "reserved, unused: refile"); 387 /* 388 * A journal_get_undo_access()+journal_release_buffer() may 389 * leave undo-committed data. 390 */ 391 if (jh->b_committed_data) { 392 struct buffer_head *bh = jh2bh(jh); 393 394 jbd_lock_bh_state(bh); 395 jbd_free(jh->b_committed_data, bh->b_size); 396 jh->b_committed_data = NULL; 397 jbd_unlock_bh_state(bh); 398 } 399 journal_refile_buffer(journal, jh); 400 } 401 402 /* 403 * Now try to drop any written-back buffers from the journal's 404 * checkpoint lists. We do this *before* commit because it potentially 405 * frees some memory 406 */ 407 spin_lock(&journal->j_list_lock); 408 __journal_clean_checkpoint_list(journal); 409 spin_unlock(&journal->j_list_lock); 410 411 jbd_debug (3, "JBD: commit phase 1\n"); 412 413 /* 414 * Switch to a new revoke table. 415 */ 416 journal_switch_revoke_table(journal); 417 418 commit_transaction->t_state = T_FLUSH; 419 journal->j_committing_transaction = commit_transaction; 420 journal->j_running_transaction = NULL; 421 commit_transaction->t_log_start = journal->j_head; 422 wake_up(&journal->j_wait_transaction_locked); 423 spin_unlock(&journal->j_state_lock); 424 425 jbd_debug (3, "JBD: commit phase 2\n"); 426 427 /* 428 * Now start flushing things to disk, in the order they appear 429 * on the transaction lists. Data blocks go first. 430 */ 431 err = journal_submit_data_buffers(journal, commit_transaction); 432 433 /* 434 * Wait for all previously submitted IO to complete. 435 */ 436 spin_lock(&journal->j_list_lock); 437 while (commit_transaction->t_locked_list) { 438 struct buffer_head *bh; 439 440 jh = commit_transaction->t_locked_list->b_tprev; 441 bh = jh2bh(jh); 442 get_bh(bh); 443 if (buffer_locked(bh)) { 444 spin_unlock(&journal->j_list_lock); 445 wait_on_buffer(bh); 446 spin_lock(&journal->j_list_lock); 447 } 448 if (unlikely(!buffer_uptodate(bh))) { 449 if (!trylock_page(bh->b_page)) { 450 spin_unlock(&journal->j_list_lock); 451 lock_page(bh->b_page); 452 spin_lock(&journal->j_list_lock); 453 } 454 if (bh->b_page->mapping) 455 set_bit(AS_EIO, &bh->b_page->mapping->flags); 456 457 unlock_page(bh->b_page); 458 SetPageError(bh->b_page); 459 err = -EIO; 460 } 461 if (!inverted_lock(journal, bh)) { 462 put_bh(bh); 463 spin_lock(&journal->j_list_lock); 464 continue; 465 } 466 if (buffer_jbd(bh) && jh->b_jlist == BJ_Locked) { 467 __journal_unfile_buffer(jh); 468 jbd_unlock_bh_state(bh); 469 journal_remove_journal_head(bh); 470 put_bh(bh); 471 } else { 472 jbd_unlock_bh_state(bh); 473 } 474 release_data_buffer(bh); 475 cond_resched_lock(&journal->j_list_lock); 476 } 477 spin_unlock(&journal->j_list_lock); 478 479 if (err) { 480 char b[BDEVNAME_SIZE]; 481 482 printk(KERN_WARNING 483 "JBD: Detected IO errors while flushing file data " 484 "on %s\n", bdevname(journal->j_fs_dev, b)); 485 if (journal->j_flags & JFS_ABORT_ON_SYNCDATA_ERR) 486 journal_abort(journal, err); 487 err = 0; 488 } 489 490 journal_write_revoke_records(journal, commit_transaction); 491 492 /* 493 * If we found any dirty or locked buffers, then we should have 494 * looped back up to the write_out_data label. If there weren't 495 * any then journal_clean_data_list should have wiped the list 496 * clean by now, so check that it is in fact empty. 497 */ 498 J_ASSERT (commit_transaction->t_sync_datalist == NULL); 499 500 jbd_debug (3, "JBD: commit phase 3\n"); 501 502 /* 503 * Way to go: we have now written out all of the data for a 504 * transaction! Now comes the tricky part: we need to write out 505 * metadata. Loop over the transaction's entire buffer list: 506 */ 507 spin_lock(&journal->j_state_lock); 508 commit_transaction->t_state = T_COMMIT; 509 spin_unlock(&journal->j_state_lock); 510 511 J_ASSERT(commit_transaction->t_nr_buffers <= 512 commit_transaction->t_outstanding_credits); 513 514 descriptor = NULL; 515 bufs = 0; 516 while (commit_transaction->t_buffers) { 517 518 /* Find the next buffer to be journaled... */ 519 520 jh = commit_transaction->t_buffers; 521 522 /* If we're in abort mode, we just un-journal the buffer and 523 release it. */ 524 525 if (is_journal_aborted(journal)) { 526 clear_buffer_jbddirty(jh2bh(jh)); 527 JBUFFER_TRACE(jh, "journal is aborting: refile"); 528 journal_refile_buffer(journal, jh); 529 /* If that was the last one, we need to clean up 530 * any descriptor buffers which may have been 531 * already allocated, even if we are now 532 * aborting. */ 533 if (!commit_transaction->t_buffers) 534 goto start_journal_io; 535 continue; 536 } 537 538 /* Make sure we have a descriptor block in which to 539 record the metadata buffer. */ 540 541 if (!descriptor) { 542 struct buffer_head *bh; 543 544 J_ASSERT (bufs == 0); 545 546 jbd_debug(4, "JBD: get descriptor\n"); 547 548 descriptor = journal_get_descriptor_buffer(journal); 549 if (!descriptor) { 550 journal_abort(journal, -EIO); 551 continue; 552 } 553 554 bh = jh2bh(descriptor); 555 jbd_debug(4, "JBD: got buffer %llu (%p)\n", 556 (unsigned long long)bh->b_blocknr, bh->b_data); 557 header = (journal_header_t *)&bh->b_data[0]; 558 header->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER); 559 header->h_blocktype = cpu_to_be32(JFS_DESCRIPTOR_BLOCK); 560 header->h_sequence = cpu_to_be32(commit_transaction->t_tid); 561 562 tagp = &bh->b_data[sizeof(journal_header_t)]; 563 space_left = bh->b_size - sizeof(journal_header_t); 564 first_tag = 1; 565 set_buffer_jwrite(bh); 566 set_buffer_dirty(bh); 567 wbuf[bufs++] = bh; 568 569 /* Record it so that we can wait for IO 570 completion later */ 571 BUFFER_TRACE(bh, "ph3: file as descriptor"); 572 journal_file_buffer(descriptor, commit_transaction, 573 BJ_LogCtl); 574 } 575 576 /* Where is the buffer to be written? */ 577 578 err = journal_next_log_block(journal, &blocknr); 579 /* If the block mapping failed, just abandon the buffer 580 and repeat this loop: we'll fall into the 581 refile-on-abort condition above. */ 582 if (err) { 583 journal_abort(journal, err); 584 continue; 585 } 586 587 /* 588 * start_this_handle() uses t_outstanding_credits to determine 589 * the free space in the log, but this counter is changed 590 * by journal_next_log_block() also. 591 */ 592 commit_transaction->t_outstanding_credits--; 593 594 /* Bump b_count to prevent truncate from stumbling over 595 the shadowed buffer! @@@ This can go if we ever get 596 rid of the BJ_IO/BJ_Shadow pairing of buffers. */ 597 atomic_inc(&jh2bh(jh)->b_count); 598 599 /* Make a temporary IO buffer with which to write it out 600 (this will requeue both the metadata buffer and the 601 temporary IO buffer). new_bh goes on BJ_IO*/ 602 603 set_bit(BH_JWrite, &jh2bh(jh)->b_state); 604 /* 605 * akpm: journal_write_metadata_buffer() sets 606 * new_bh->b_transaction to commit_transaction. 607 * We need to clean this up before we release new_bh 608 * (which is of type BJ_IO) 609 */ 610 JBUFFER_TRACE(jh, "ph3: write metadata"); 611 flags = journal_write_metadata_buffer(commit_transaction, 612 jh, &new_jh, blocknr); 613 set_bit(BH_JWrite, &jh2bh(new_jh)->b_state); 614 wbuf[bufs++] = jh2bh(new_jh); 615 616 /* Record the new block's tag in the current descriptor 617 buffer */ 618 619 tag_flag = 0; 620 if (flags & 1) 621 tag_flag |= JFS_FLAG_ESCAPE; 622 if (!first_tag) 623 tag_flag |= JFS_FLAG_SAME_UUID; 624 625 tag = (journal_block_tag_t *) tagp; 626 tag->t_blocknr = cpu_to_be32(jh2bh(jh)->b_blocknr); 627 tag->t_flags = cpu_to_be32(tag_flag); 628 tagp += sizeof(journal_block_tag_t); 629 space_left -= sizeof(journal_block_tag_t); 630 631 if (first_tag) { 632 memcpy (tagp, journal->j_uuid, 16); 633 tagp += 16; 634 space_left -= 16; 635 first_tag = 0; 636 } 637 638 /* If there's no more to do, or if the descriptor is full, 639 let the IO rip! */ 640 641 if (bufs == journal->j_wbufsize || 642 commit_transaction->t_buffers == NULL || 643 space_left < sizeof(journal_block_tag_t) + 16) { 644 645 jbd_debug(4, "JBD: Submit %d IOs\n", bufs); 646 647 /* Write an end-of-descriptor marker before 648 submitting the IOs. "tag" still points to 649 the last tag we set up. */ 650 651 tag->t_flags |= cpu_to_be32(JFS_FLAG_LAST_TAG); 652 653start_journal_io: 654 for (i = 0; i < bufs; i++) { 655 struct buffer_head *bh = wbuf[i]; 656 lock_buffer(bh); 657 clear_buffer_dirty(bh); 658 set_buffer_uptodate(bh); 659 bh->b_end_io = journal_end_buffer_io_sync; 660 submit_bh(WRITE, bh); 661 } 662 cond_resched(); 663 664 /* Force a new descriptor to be generated next 665 time round the loop. */ 666 descriptor = NULL; 667 bufs = 0; 668 } 669 } 670 671 /* Lo and behold: we have just managed to send a transaction to 672 the log. Before we can commit it, wait for the IO so far to 673 complete. Control buffers being written are on the 674 transaction's t_log_list queue, and metadata buffers are on 675 the t_iobuf_list queue. 676 677 Wait for the buffers in reverse order. That way we are 678 less likely to be woken up until all IOs have completed, and 679 so we incur less scheduling load. 680 */ 681 682 jbd_debug(3, "JBD: commit phase 4\n"); 683 684 /* 685 * akpm: these are BJ_IO, and j_list_lock is not needed. 686 * See __journal_try_to_free_buffer. 687 */ 688wait_for_iobuf: 689 while (commit_transaction->t_iobuf_list != NULL) { 690 struct buffer_head *bh; 691 692 jh = commit_transaction->t_iobuf_list->b_tprev; 693 bh = jh2bh(jh); 694 if (buffer_locked(bh)) { 695 wait_on_buffer(bh); 696 goto wait_for_iobuf; 697 } 698 if (cond_resched()) 699 goto wait_for_iobuf; 700 701 if (unlikely(!buffer_uptodate(bh))) 702 err = -EIO; 703 704 clear_buffer_jwrite(bh); 705 706 JBUFFER_TRACE(jh, "ph4: unfile after journal write"); 707 journal_unfile_buffer(journal, jh); 708 709 /* 710 * ->t_iobuf_list should contain only dummy buffer_heads 711 * which were created by journal_write_metadata_buffer(). 712 */ 713 BUFFER_TRACE(bh, "dumping temporary bh"); 714 journal_put_journal_head(jh); 715 __brelse(bh); 716 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0); 717 free_buffer_head(bh); 718 719 /* We also have to unlock and free the corresponding 720 shadowed buffer */ 721 jh = commit_transaction->t_shadow_list->b_tprev; 722 bh = jh2bh(jh); 723 clear_bit(BH_JWrite, &bh->b_state); 724 J_ASSERT_BH(bh, buffer_jbddirty(bh)); 725 726 /* The metadata is now released for reuse, but we need 727 to remember it against this transaction so that when 728 we finally commit, we can do any checkpointing 729 required. */ 730 JBUFFER_TRACE(jh, "file as BJ_Forget"); 731 journal_file_buffer(jh, commit_transaction, BJ_Forget); 732 /* Wake up any transactions which were waiting for this 733 IO to complete */ 734 wake_up_bit(&bh->b_state, BH_Unshadow); 735 JBUFFER_TRACE(jh, "brelse shadowed buffer"); 736 __brelse(bh); 737 } 738 739 J_ASSERT (commit_transaction->t_shadow_list == NULL); 740 741 jbd_debug(3, "JBD: commit phase 5\n"); 742 743 /* Here we wait for the revoke record and descriptor record buffers */ 744 wait_for_ctlbuf: 745 while (commit_transaction->t_log_list != NULL) { 746 struct buffer_head *bh; 747 748 jh = commit_transaction->t_log_list->b_tprev; 749 bh = jh2bh(jh); 750 if (buffer_locked(bh)) { 751 wait_on_buffer(bh); 752 goto wait_for_ctlbuf; 753 } 754 if (cond_resched()) 755 goto wait_for_ctlbuf; 756 757 if (unlikely(!buffer_uptodate(bh))) 758 err = -EIO; 759 760 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile"); 761 clear_buffer_jwrite(bh); 762 journal_unfile_buffer(journal, jh); 763 journal_put_journal_head(jh); 764 __brelse(bh); /* One for getblk */ 765 /* AKPM: bforget here */ 766 } 767 768 if (err) 769 journal_abort(journal, err); 770 771 jbd_debug(3, "JBD: commit phase 6\n"); 772 773 if (journal_write_commit_record(journal, commit_transaction)) 774 err = -EIO; 775 776 if (err) 777 journal_abort(journal, err); 778 779 /* End of a transaction! Finally, we can do checkpoint 780 processing: any buffers committed as a result of this 781 transaction can be removed from any checkpoint list it was on 782 before. */ 783 784 jbd_debug(3, "JBD: commit phase 7\n"); 785 786 J_ASSERT(commit_transaction->t_sync_datalist == NULL); 787 J_ASSERT(commit_transaction->t_buffers == NULL); 788 J_ASSERT(commit_transaction->t_checkpoint_list == NULL); 789 J_ASSERT(commit_transaction->t_iobuf_list == NULL); 790 J_ASSERT(commit_transaction->t_shadow_list == NULL); 791 J_ASSERT(commit_transaction->t_log_list == NULL); 792 793restart_loop: 794 /* 795 * As there are other places (journal_unmap_buffer()) adding buffers 796 * to this list we have to be careful and hold the j_list_lock. 797 */ 798 spin_lock(&journal->j_list_lock); 799 while (commit_transaction->t_forget) { 800 transaction_t *cp_transaction; 801 struct buffer_head *bh; 802 803 jh = commit_transaction->t_forget; 804 spin_unlock(&journal->j_list_lock); 805 bh = jh2bh(jh); 806 jbd_lock_bh_state(bh); 807 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction || 808 jh->b_transaction == journal->j_running_transaction); 809 810 /* 811 * If there is undo-protected committed data against 812 * this buffer, then we can remove it now. If it is a 813 * buffer needing such protection, the old frozen_data 814 * field now points to a committed version of the 815 * buffer, so rotate that field to the new committed 816 * data. 817 * 818 * Otherwise, we can just throw away the frozen data now. 819 */ 820 if (jh->b_committed_data) { 821 jbd_free(jh->b_committed_data, bh->b_size); 822 jh->b_committed_data = NULL; 823 if (jh->b_frozen_data) { 824 jh->b_committed_data = jh->b_frozen_data; 825 jh->b_frozen_data = NULL; 826 } 827 } else if (jh->b_frozen_data) { 828 jbd_free(jh->b_frozen_data, bh->b_size); 829 jh->b_frozen_data = NULL; 830 } 831 832 spin_lock(&journal->j_list_lock); 833 cp_transaction = jh->b_cp_transaction; 834 if (cp_transaction) { 835 JBUFFER_TRACE(jh, "remove from old cp transaction"); 836 __journal_remove_checkpoint(jh); 837 } 838 839 /* Only re-checkpoint the buffer_head if it is marked 840 * dirty. If the buffer was added to the BJ_Forget list 841 * by journal_forget, it may no longer be dirty and 842 * there's no point in keeping a checkpoint record for 843 * it. */ 844 845 /* A buffer which has been freed while still being 846 * journaled by a previous transaction may end up still 847 * being dirty here, but we want to avoid writing back 848 * that buffer in the future now that the last use has 849 * been committed. That's not only a performance gain, 850 * it also stops aliasing problems if the buffer is left 851 * behind for writeback and gets reallocated for another 852 * use in a different page. */ 853 if (buffer_freed(bh)) { 854 clear_buffer_freed(bh); 855 clear_buffer_jbddirty(bh); 856 } 857 858 if (buffer_jbddirty(bh)) { 859 JBUFFER_TRACE(jh, "add to new checkpointing trans"); 860 __journal_insert_checkpoint(jh, commit_transaction); 861 if (is_journal_aborted(journal)) 862 clear_buffer_jbddirty(bh); 863 JBUFFER_TRACE(jh, "refile for checkpoint writeback"); 864 __journal_refile_buffer(jh); 865 jbd_unlock_bh_state(bh); 866 } else { 867 J_ASSERT_BH(bh, !buffer_dirty(bh)); 868 /* The buffer on BJ_Forget list and not jbddirty means 869 * it has been freed by this transaction and hence it 870 * could not have been reallocated until this 871 * transaction has committed. *BUT* it could be 872 * reallocated once we have written all the data to 873 * disk and before we process the buffer on BJ_Forget 874 * list. */ 875 JBUFFER_TRACE(jh, "refile or unfile freed buffer"); 876 __journal_refile_buffer(jh); 877 if (!jh->b_transaction) { 878 jbd_unlock_bh_state(bh); 879 /* needs a brelse */ 880 journal_remove_journal_head(bh); 881 release_buffer_page(bh); 882 } else 883 jbd_unlock_bh_state(bh); 884 } 885 cond_resched_lock(&journal->j_list_lock); 886 } 887 spin_unlock(&journal->j_list_lock); 888 /* 889 * This is a bit sleazy. We use j_list_lock to protect transition 890 * of a transaction into T_FINISHED state and calling 891 * __journal_drop_transaction(). Otherwise we could race with 892 * other checkpointing code processing the transaction... 893 */ 894 spin_lock(&journal->j_state_lock); 895 spin_lock(&journal->j_list_lock); 896 /* 897 * Now recheck if some buffers did not get attached to the transaction 898 * while the lock was dropped... 899 */ 900 if (commit_transaction->t_forget) { 901 spin_unlock(&journal->j_list_lock); 902 spin_unlock(&journal->j_state_lock); 903 goto restart_loop; 904 } 905 906 /* Done with this transaction! */ 907 908 jbd_debug(3, "JBD: commit phase 8\n"); 909 910 J_ASSERT(commit_transaction->t_state == T_COMMIT); 911 912 commit_transaction->t_state = T_FINISHED; 913 J_ASSERT(commit_transaction == journal->j_committing_transaction); 914 journal->j_commit_sequence = commit_transaction->t_tid; 915 journal->j_committing_transaction = NULL; 916 spin_unlock(&journal->j_state_lock); 917 918 if (commit_transaction->t_checkpoint_list == NULL && 919 commit_transaction->t_checkpoint_io_list == NULL) { 920 __journal_drop_transaction(journal, commit_transaction); 921 } else { 922 if (journal->j_checkpoint_transactions == NULL) { 923 journal->j_checkpoint_transactions = commit_transaction; 924 commit_transaction->t_cpnext = commit_transaction; 925 commit_transaction->t_cpprev = commit_transaction; 926 } else { 927 commit_transaction->t_cpnext = 928 journal->j_checkpoint_transactions; 929 commit_transaction->t_cpprev = 930 commit_transaction->t_cpnext->t_cpprev; 931 commit_transaction->t_cpnext->t_cpprev = 932 commit_transaction; 933 commit_transaction->t_cpprev->t_cpnext = 934 commit_transaction; 935 } 936 } 937 spin_unlock(&journal->j_list_lock); 938 939 jbd_debug(1, "JBD: commit %d complete, head %d\n", 940 journal->j_commit_sequence, journal->j_tail_sequence); 941 942 wake_up(&journal->j_wait_done_commit); 943}