1 /* 2 * linux/fs/jbd2/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/jbd2.h> 19 #include <linux/errno.h> 20 #include <linux/slab.h> 21 #include <linux/mm.h> 22 #include <linux/pagemap.h> 23 #include <linux/jiffies.h> 24 #include <linux/crc32.h> 25 #include <linux/writeback.h> 26 #include <linux/backing-dev.h> 27 28 /* 29 * Default IO end handler for temporary BJ_IO buffer_heads. 30 */ 31 static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate) 32 { 33 BUFFER_TRACE(bh, ""); 34 if (uptodate) 35 set_buffer_uptodate(bh); 36 else 37 clear_buffer_uptodate(bh); 38 unlock_buffer(bh); 39 } 40 41 /* 42 * When an ext4 file is truncated, it is possible that some pages are not 43 * successfully freed, because they are attached to a committing transaction. 44 * After the transaction commits, these pages are left on the LRU, with no 45 * ->mapping, and with attached buffers. These pages are trivially reclaimable 46 * by the VM, but their apparent absence upsets the VM accounting, and it makes 47 * the numbers in /proc/meminfo look odd. 48 * 49 * So here, we have a buffer which has just come off the forget list. Look to 50 * see if we can strip all buffers from the backing page. 51 * 52 * Called under lock_journal(), and possibly under journal_datalist_lock. The 53 * caller provided us with a ref against the buffer, and we drop that here. 54 */ 55 static void release_buffer_page(struct buffer_head *bh) 56 { 57 struct page *page; 58 59 if (buffer_dirty(bh)) 60 goto nope; 61 if (atomic_read(&bh->b_count) != 1) 62 goto nope; 63 page = bh->b_page; 64 if (!page) 65 goto nope; 66 if (page->mapping) 67 goto nope; 68 69 /* OK, it's a truncated page */ 70 if (!trylock_page(page)) 71 goto nope; 72 73 page_cache_get(page); 74 __brelse(bh); 75 try_to_free_buffers(page); 76 unlock_page(page); 77 page_cache_release(page); 78 return; 79 80 nope: 81 __brelse(bh); 82 } 83 84 /* 85 * Done it all: now submit the commit record. We should have 86 * cleaned up our previous buffers by now, so if we are in abort 87 * mode we can now just skip the rest of the journal write 88 * entirely. 89 * 90 * Returns 1 if the journal needs to be aborted or 0 on success 91 */ 92 static int journal_submit_commit_record(journal_t *journal, 93 transaction_t *commit_transaction, 94 struct buffer_head **cbh, 95 __u32 crc32_sum) 96 { 97 struct journal_head *descriptor; 98 struct commit_header *tmp; 99 struct buffer_head *bh; 100 int ret; 101 int barrier_done = 0; 102 struct timespec now = current_kernel_time(); 103 104 if (is_journal_aborted(journal)) 105 return 0; 106 107 descriptor = jbd2_journal_get_descriptor_buffer(journal); 108 if (!descriptor) 109 return 1; 110 111 bh = jh2bh(descriptor); 112 113 tmp = (struct commit_header *)bh->b_data; 114 tmp->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER); 115 tmp->h_blocktype = cpu_to_be32(JBD2_COMMIT_BLOCK); 116 tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid); 117 tmp->h_commit_sec = cpu_to_be64(now.tv_sec); 118 tmp->h_commit_nsec = cpu_to_be32(now.tv_nsec); 119 120 if (JBD2_HAS_COMPAT_FEATURE(journal, 121 JBD2_FEATURE_COMPAT_CHECKSUM)) { 122 tmp->h_chksum_type = JBD2_CRC32_CHKSUM; 123 tmp->h_chksum_size = JBD2_CRC32_CHKSUM_SIZE; 124 tmp->h_chksum[0] = cpu_to_be32(crc32_sum); 125 } 126 127 JBUFFER_TRACE(descriptor, "submit commit block"); 128 lock_buffer(bh); 129 get_bh(bh); 130 set_buffer_dirty(bh); 131 set_buffer_uptodate(bh); 132 bh->b_end_io = journal_end_buffer_io_sync; 133 134 if (journal->j_flags & JBD2_BARRIER && 135 !JBD2_HAS_INCOMPAT_FEATURE(journal, 136 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { 137 set_buffer_ordered(bh); 138 barrier_done = 1; 139 } 140 ret = submit_bh(WRITE, bh); 141 if (barrier_done) 142 clear_buffer_ordered(bh); 143 144 /* is it possible for another commit to fail at roughly 145 * the same time as this one? If so, we don't want to 146 * trust the barrier flag in the super, but instead want 147 * to remember if we sent a barrier request 148 */ 149 if (ret == -EOPNOTSUPP && barrier_done) { 150 char b[BDEVNAME_SIZE]; 151 152 printk(KERN_WARNING 153 "JBD: barrier-based sync failed on %s - " 154 "disabling barriers\n", 155 bdevname(journal->j_dev, b)); 156 spin_lock(&journal->j_state_lock); 157 journal->j_flags &= ~JBD2_BARRIER; 158 spin_unlock(&journal->j_state_lock); 159 160 /* And try again, without the barrier */ 161 lock_buffer(bh); 162 set_buffer_uptodate(bh); 163 set_buffer_dirty(bh); 164 ret = submit_bh(WRITE, bh); 165 } 166 *cbh = bh; 167 return ret; 168 } 169 170 /* 171 * This function along with journal_submit_commit_record 172 * allows to write the commit record asynchronously. 173 */ 174 static int journal_wait_on_commit_record(struct buffer_head *bh) 175 { 176 int ret = 0; 177 178 clear_buffer_dirty(bh); 179 wait_on_buffer(bh); 180 181 if (unlikely(!buffer_uptodate(bh))) 182 ret = -EIO; 183 put_bh(bh); /* One for getblk() */ 184 jbd2_journal_put_journal_head(bh2jh(bh)); 185 186 return ret; 187 } 188 189 /* 190 * write the filemap data using writepage() address_space_operations. 191 * We don't do block allocation here even for delalloc. We don't 192 * use writepages() because with dealyed allocation we may be doing 193 * block allocation in writepages(). 194 */ 195 static int journal_submit_inode_data_buffers(struct address_space *mapping) 196 { 197 int ret; 198 struct writeback_control wbc = { 199 .sync_mode = WB_SYNC_ALL, 200 .nr_to_write = mapping->nrpages * 2, 201 .range_start = 0, 202 .range_end = i_size_read(mapping->host), 203 .for_writepages = 1, 204 }; 205 206 ret = generic_writepages(mapping, &wbc); 207 return ret; 208 } 209 210 /* 211 * Submit all the data buffers of inode associated with the transaction to 212 * disk. 213 * 214 * We are in a committing transaction. Therefore no new inode can be added to 215 * our inode list. We use JI_COMMIT_RUNNING flag to protect inode we currently 216 * operate on from being released while we write out pages. 217 */ 218 static int journal_submit_data_buffers(journal_t *journal, 219 transaction_t *commit_transaction) 220 { 221 struct jbd2_inode *jinode; 222 int err, ret = 0; 223 struct address_space *mapping; 224 225 spin_lock(&journal->j_list_lock); 226 list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) { 227 mapping = jinode->i_vfs_inode->i_mapping; 228 jinode->i_flags |= JI_COMMIT_RUNNING; 229 spin_unlock(&journal->j_list_lock); 230 /* 231 * submit the inode data buffers. We use writepage 232 * instead of writepages. Because writepages can do 233 * block allocation with delalloc. We need to write 234 * only allocated blocks here. 235 */ 236 err = journal_submit_inode_data_buffers(mapping); 237 if (!ret) 238 ret = err; 239 spin_lock(&journal->j_list_lock); 240 J_ASSERT(jinode->i_transaction == commit_transaction); 241 jinode->i_flags &= ~JI_COMMIT_RUNNING; 242 wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING); 243 } 244 spin_unlock(&journal->j_list_lock); 245 return ret; 246 } 247 248 /* 249 * Wait for data submitted for writeout, refile inodes to proper 250 * transaction if needed. 251 * 252 */ 253 static int journal_finish_inode_data_buffers(journal_t *journal, 254 transaction_t *commit_transaction) 255 { 256 struct jbd2_inode *jinode, *next_i; 257 int err, ret = 0; 258 259 /* For locking, see the comment in journal_submit_data_buffers() */ 260 spin_lock(&journal->j_list_lock); 261 list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) { 262 jinode->i_flags |= JI_COMMIT_RUNNING; 263 spin_unlock(&journal->j_list_lock); 264 err = filemap_fdatawait(jinode->i_vfs_inode->i_mapping); 265 if (err) { 266 /* 267 * Because AS_EIO is cleared by 268 * wait_on_page_writeback_range(), set it again so 269 * that user process can get -EIO from fsync(). 270 */ 271 set_bit(AS_EIO, 272 &jinode->i_vfs_inode->i_mapping->flags); 273 274 if (!ret) 275 ret = err; 276 } 277 spin_lock(&journal->j_list_lock); 278 jinode->i_flags &= ~JI_COMMIT_RUNNING; 279 wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING); 280 } 281 282 /* Now refile inode to proper lists */ 283 list_for_each_entry_safe(jinode, next_i, 284 &commit_transaction->t_inode_list, i_list) { 285 list_del(&jinode->i_list); 286 if (jinode->i_next_transaction) { 287 jinode->i_transaction = jinode->i_next_transaction; 288 jinode->i_next_transaction = NULL; 289 list_add(&jinode->i_list, 290 &jinode->i_transaction->t_inode_list); 291 } else { 292 jinode->i_transaction = NULL; 293 } 294 } 295 spin_unlock(&journal->j_list_lock); 296 297 return ret; 298 } 299 300 static __u32 jbd2_checksum_data(__u32 crc32_sum, struct buffer_head *bh) 301 { 302 struct page *page = bh->b_page; 303 char *addr; 304 __u32 checksum; 305 306 addr = kmap_atomic(page, KM_USER0); 307 checksum = crc32_be(crc32_sum, 308 (void *)(addr + offset_in_page(bh->b_data)), bh->b_size); 309 kunmap_atomic(addr, KM_USER0); 310 311 return checksum; 312 } 313 314 static void write_tag_block(int tag_bytes, journal_block_tag_t *tag, 315 unsigned long long block) 316 { 317 tag->t_blocknr = cpu_to_be32(block & (u32)~0); 318 if (tag_bytes > JBD2_TAG_SIZE32) 319 tag->t_blocknr_high = cpu_to_be32((block >> 31) >> 1); 320 } 321 322 /* 323 * jbd2_journal_commit_transaction 324 * 325 * The primary function for committing a transaction to the log. This 326 * function is called by the journal thread to begin a complete commit. 327 */ 328 void jbd2_journal_commit_transaction(journal_t *journal) 329 { 330 struct transaction_stats_s stats; 331 transaction_t *commit_transaction; 332 struct journal_head *jh, *new_jh, *descriptor; 333 struct buffer_head **wbuf = journal->j_wbuf; 334 int bufs; 335 int flags; 336 int err; 337 unsigned long long blocknr; 338 char *tagp = NULL; 339 journal_header_t *header; 340 journal_block_tag_t *tag = NULL; 341 int space_left = 0; 342 int first_tag = 0; 343 int tag_flag; 344 int i; 345 int tag_bytes = journal_tag_bytes(journal); 346 struct buffer_head *cbh = NULL; /* For transactional checksums */ 347 __u32 crc32_sum = ~0; 348 349 /* 350 * First job: lock down the current transaction and wait for 351 * all outstanding updates to complete. 352 */ 353 354 #ifdef COMMIT_STATS 355 spin_lock(&journal->j_list_lock); 356 summarise_journal_usage(journal); 357 spin_unlock(&journal->j_list_lock); 358 #endif 359 360 /* Do we need to erase the effects of a prior jbd2_journal_flush? */ 361 if (journal->j_flags & JBD2_FLUSHED) { 362 jbd_debug(3, "super block updated\n"); 363 jbd2_journal_update_superblock(journal, 1); 364 } else { 365 jbd_debug(3, "superblock not updated\n"); 366 } 367 368 J_ASSERT(journal->j_running_transaction != NULL); 369 J_ASSERT(journal->j_committing_transaction == NULL); 370 371 commit_transaction = journal->j_running_transaction; 372 J_ASSERT(commit_transaction->t_state == T_RUNNING); 373 374 jbd_debug(1, "JBD: starting commit of transaction %d\n", 375 commit_transaction->t_tid); 376 377 spin_lock(&journal->j_state_lock); 378 commit_transaction->t_state = T_LOCKED; 379 380 stats.u.run.rs_wait = commit_transaction->t_max_wait; 381 stats.u.run.rs_locked = jiffies; 382 stats.u.run.rs_running = jbd2_time_diff(commit_transaction->t_start, 383 stats.u.run.rs_locked); 384 385 spin_lock(&commit_transaction->t_handle_lock); 386 while (commit_transaction->t_updates) { 387 DEFINE_WAIT(wait); 388 389 prepare_to_wait(&journal->j_wait_updates, &wait, 390 TASK_UNINTERRUPTIBLE); 391 if (commit_transaction->t_updates) { 392 spin_unlock(&commit_transaction->t_handle_lock); 393 spin_unlock(&journal->j_state_lock); 394 schedule(); 395 spin_lock(&journal->j_state_lock); 396 spin_lock(&commit_transaction->t_handle_lock); 397 } 398 finish_wait(&journal->j_wait_updates, &wait); 399 } 400 spin_unlock(&commit_transaction->t_handle_lock); 401 402 J_ASSERT (commit_transaction->t_outstanding_credits <= 403 journal->j_max_transaction_buffers); 404 405 /* 406 * First thing we are allowed to do is to discard any remaining 407 * BJ_Reserved buffers. Note, it is _not_ permissible to assume 408 * that there are no such buffers: if a large filesystem 409 * operation like a truncate needs to split itself over multiple 410 * transactions, then it may try to do a jbd2_journal_restart() while 411 * there are still BJ_Reserved buffers outstanding. These must 412 * be released cleanly from the current transaction. 413 * 414 * In this case, the filesystem must still reserve write access 415 * again before modifying the buffer in the new transaction, but 416 * we do not require it to remember exactly which old buffers it 417 * has reserved. This is consistent with the existing behaviour 418 * that multiple jbd2_journal_get_write_access() calls to the same 419 * buffer are perfectly permissable. 420 */ 421 while (commit_transaction->t_reserved_list) { 422 jh = commit_transaction->t_reserved_list; 423 JBUFFER_TRACE(jh, "reserved, unused: refile"); 424 /* 425 * A jbd2_journal_get_undo_access()+jbd2_journal_release_buffer() may 426 * leave undo-committed data. 427 */ 428 if (jh->b_committed_data) { 429 struct buffer_head *bh = jh2bh(jh); 430 431 jbd_lock_bh_state(bh); 432 jbd2_free(jh->b_committed_data, bh->b_size); 433 jh->b_committed_data = NULL; 434 jbd_unlock_bh_state(bh); 435 } 436 jbd2_journal_refile_buffer(journal, jh); 437 } 438 439 /* 440 * Now try to drop any written-back buffers from the journal's 441 * checkpoint lists. We do this *before* commit because it potentially 442 * frees some memory 443 */ 444 spin_lock(&journal->j_list_lock); 445 __jbd2_journal_clean_checkpoint_list(journal); 446 spin_unlock(&journal->j_list_lock); 447 448 jbd_debug (3, "JBD: commit phase 1\n"); 449 450 /* 451 * Switch to a new revoke table. 452 */ 453 jbd2_journal_switch_revoke_table(journal); 454 455 stats.u.run.rs_flushing = jiffies; 456 stats.u.run.rs_locked = jbd2_time_diff(stats.u.run.rs_locked, 457 stats.u.run.rs_flushing); 458 459 commit_transaction->t_state = T_FLUSH; 460 journal->j_committing_transaction = commit_transaction; 461 journal->j_running_transaction = NULL; 462 commit_transaction->t_log_start = journal->j_head; 463 wake_up(&journal->j_wait_transaction_locked); 464 spin_unlock(&journal->j_state_lock); 465 466 jbd_debug (3, "JBD: commit phase 2\n"); 467 468 /* 469 * Now start flushing things to disk, in the order they appear 470 * on the transaction lists. Data blocks go first. 471 */ 472 err = journal_submit_data_buffers(journal, commit_transaction); 473 if (err) 474 jbd2_journal_abort(journal, err); 475 476 jbd2_journal_write_revoke_records(journal, commit_transaction); 477 478 jbd_debug(3, "JBD: commit phase 2\n"); 479 480 /* 481 * Way to go: we have now written out all of the data for a 482 * transaction! Now comes the tricky part: we need to write out 483 * metadata. Loop over the transaction's entire buffer list: 484 */ 485 spin_lock(&journal->j_state_lock); 486 commit_transaction->t_state = T_COMMIT; 487 spin_unlock(&journal->j_state_lock); 488 489 stats.u.run.rs_logging = jiffies; 490 stats.u.run.rs_flushing = jbd2_time_diff(stats.u.run.rs_flushing, 491 stats.u.run.rs_logging); 492 stats.u.run.rs_blocks = commit_transaction->t_outstanding_credits; 493 stats.u.run.rs_blocks_logged = 0; 494 495 J_ASSERT(commit_transaction->t_nr_buffers <= 496 commit_transaction->t_outstanding_credits); 497 498 err = 0; 499 descriptor = NULL; 500 bufs = 0; 501 while (commit_transaction->t_buffers) { 502 503 /* Find the next buffer to be journaled... */ 504 505 jh = commit_transaction->t_buffers; 506 507 /* If we're in abort mode, we just un-journal the buffer and 508 release it for background writing. */ 509 510 if (is_journal_aborted(journal)) { 511 JBUFFER_TRACE(jh, "journal is aborting: refile"); 512 jbd2_journal_refile_buffer(journal, jh); 513 /* If that was the last one, we need to clean up 514 * any descriptor buffers which may have been 515 * already allocated, even if we are now 516 * aborting. */ 517 if (!commit_transaction->t_buffers) 518 goto start_journal_io; 519 continue; 520 } 521 522 /* Make sure we have a descriptor block in which to 523 record the metadata buffer. */ 524 525 if (!descriptor) { 526 struct buffer_head *bh; 527 528 J_ASSERT (bufs == 0); 529 530 jbd_debug(4, "JBD: get descriptor\n"); 531 532 descriptor = jbd2_journal_get_descriptor_buffer(journal); 533 if (!descriptor) { 534 jbd2_journal_abort(journal, -EIO); 535 continue; 536 } 537 538 bh = jh2bh(descriptor); 539 jbd_debug(4, "JBD: got buffer %llu (%p)\n", 540 (unsigned long long)bh->b_blocknr, bh->b_data); 541 header = (journal_header_t *)&bh->b_data[0]; 542 header->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER); 543 header->h_blocktype = cpu_to_be32(JBD2_DESCRIPTOR_BLOCK); 544 header->h_sequence = cpu_to_be32(commit_transaction->t_tid); 545 546 tagp = &bh->b_data[sizeof(journal_header_t)]; 547 space_left = bh->b_size - sizeof(journal_header_t); 548 first_tag = 1; 549 set_buffer_jwrite(bh); 550 set_buffer_dirty(bh); 551 wbuf[bufs++] = bh; 552 553 /* Record it so that we can wait for IO 554 completion later */ 555 BUFFER_TRACE(bh, "ph3: file as descriptor"); 556 jbd2_journal_file_buffer(descriptor, commit_transaction, 557 BJ_LogCtl); 558 } 559 560 /* Where is the buffer to be written? */ 561 562 err = jbd2_journal_next_log_block(journal, &blocknr); 563 /* If the block mapping failed, just abandon the buffer 564 and repeat this loop: we'll fall into the 565 refile-on-abort condition above. */ 566 if (err) { 567 jbd2_journal_abort(journal, err); 568 continue; 569 } 570 571 /* 572 * start_this_handle() uses t_outstanding_credits to determine 573 * the free space in the log, but this counter is changed 574 * by jbd2_journal_next_log_block() also. 575 */ 576 commit_transaction->t_outstanding_credits--; 577 578 /* Bump b_count to prevent truncate from stumbling over 579 the shadowed buffer! @@@ This can go if we ever get 580 rid of the BJ_IO/BJ_Shadow pairing of buffers. */ 581 atomic_inc(&jh2bh(jh)->b_count); 582 583 /* Make a temporary IO buffer with which to write it out 584 (this will requeue both the metadata buffer and the 585 temporary IO buffer). new_bh goes on BJ_IO*/ 586 587 set_bit(BH_JWrite, &jh2bh(jh)->b_state); 588 /* 589 * akpm: jbd2_journal_write_metadata_buffer() sets 590 * new_bh->b_transaction to commit_transaction. 591 * We need to clean this up before we release new_bh 592 * (which is of type BJ_IO) 593 */ 594 JBUFFER_TRACE(jh, "ph3: write metadata"); 595 flags = jbd2_journal_write_metadata_buffer(commit_transaction, 596 jh, &new_jh, blocknr); 597 set_bit(BH_JWrite, &jh2bh(new_jh)->b_state); 598 wbuf[bufs++] = jh2bh(new_jh); 599 600 /* Record the new block's tag in the current descriptor 601 buffer */ 602 603 tag_flag = 0; 604 if (flags & 1) 605 tag_flag |= JBD2_FLAG_ESCAPE; 606 if (!first_tag) 607 tag_flag |= JBD2_FLAG_SAME_UUID; 608 609 tag = (journal_block_tag_t *) tagp; 610 write_tag_block(tag_bytes, tag, jh2bh(jh)->b_blocknr); 611 tag->t_flags = cpu_to_be32(tag_flag); 612 tagp += tag_bytes; 613 space_left -= tag_bytes; 614 615 if (first_tag) { 616 memcpy (tagp, journal->j_uuid, 16); 617 tagp += 16; 618 space_left -= 16; 619 first_tag = 0; 620 } 621 622 /* If there's no more to do, or if the descriptor is full, 623 let the IO rip! */ 624 625 if (bufs == journal->j_wbufsize || 626 commit_transaction->t_buffers == NULL || 627 space_left < tag_bytes + 16) { 628 629 jbd_debug(4, "JBD: Submit %d IOs\n", bufs); 630 631 /* Write an end-of-descriptor marker before 632 submitting the IOs. "tag" still points to 633 the last tag we set up. */ 634 635 tag->t_flags |= cpu_to_be32(JBD2_FLAG_LAST_TAG); 636 637 start_journal_io: 638 for (i = 0; i < bufs; i++) { 639 struct buffer_head *bh = wbuf[i]; 640 /* 641 * Compute checksum. 642 */ 643 if (JBD2_HAS_COMPAT_FEATURE(journal, 644 JBD2_FEATURE_COMPAT_CHECKSUM)) { 645 crc32_sum = 646 jbd2_checksum_data(crc32_sum, bh); 647 } 648 649 lock_buffer(bh); 650 clear_buffer_dirty(bh); 651 set_buffer_uptodate(bh); 652 bh->b_end_io = journal_end_buffer_io_sync; 653 submit_bh(WRITE, bh); 654 } 655 cond_resched(); 656 stats.u.run.rs_blocks_logged += bufs; 657 658 /* Force a new descriptor to be generated next 659 time round the loop. */ 660 descriptor = NULL; 661 bufs = 0; 662 } 663 } 664 665 /* Done it all: now write the commit record asynchronously. */ 666 667 if (JBD2_HAS_INCOMPAT_FEATURE(journal, 668 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { 669 err = journal_submit_commit_record(journal, commit_transaction, 670 &cbh, crc32_sum); 671 if (err) 672 __jbd2_journal_abort_hard(journal); 673 } 674 675 /* 676 * This is the right place to wait for data buffers both for ASYNC 677 * and !ASYNC commit. If commit is ASYNC, we need to wait only after 678 * the commit block went to disk (which happens above). If commit is 679 * SYNC, we need to wait for data buffers before we start writing 680 * commit block, which happens below in such setting. 681 */ 682 err = journal_finish_inode_data_buffers(journal, commit_transaction); 683 if (err) { 684 char b[BDEVNAME_SIZE]; 685 686 printk(KERN_WARNING 687 "JBD2: Detected IO errors while flushing file data " 688 "on %s\n", bdevname(journal->j_fs_dev, b)); 689 err = 0; 690 } 691 692 /* Lo and behold: we have just managed to send a transaction to 693 the log. Before we can commit it, wait for the IO so far to 694 complete. Control buffers being written are on the 695 transaction's t_log_list queue, and metadata buffers are on 696 the t_iobuf_list queue. 697 698 Wait for the buffers in reverse order. That way we are 699 less likely to be woken up until all IOs have completed, and 700 so we incur less scheduling load. 701 */ 702 703 jbd_debug(3, "JBD: commit phase 3\n"); 704 705 /* 706 * akpm: these are BJ_IO, and j_list_lock is not needed. 707 * See __journal_try_to_free_buffer. 708 */ 709 wait_for_iobuf: 710 while (commit_transaction->t_iobuf_list != NULL) { 711 struct buffer_head *bh; 712 713 jh = commit_transaction->t_iobuf_list->b_tprev; 714 bh = jh2bh(jh); 715 if (buffer_locked(bh)) { 716 wait_on_buffer(bh); 717 goto wait_for_iobuf; 718 } 719 if (cond_resched()) 720 goto wait_for_iobuf; 721 722 if (unlikely(!buffer_uptodate(bh))) 723 err = -EIO; 724 725 clear_buffer_jwrite(bh); 726 727 JBUFFER_TRACE(jh, "ph4: unfile after journal write"); 728 jbd2_journal_unfile_buffer(journal, jh); 729 730 /* 731 * ->t_iobuf_list should contain only dummy buffer_heads 732 * which were created by jbd2_journal_write_metadata_buffer(). 733 */ 734 BUFFER_TRACE(bh, "dumping temporary bh"); 735 jbd2_journal_put_journal_head(jh); 736 __brelse(bh); 737 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0); 738 free_buffer_head(bh); 739 740 /* We also have to unlock and free the corresponding 741 shadowed buffer */ 742 jh = commit_transaction->t_shadow_list->b_tprev; 743 bh = jh2bh(jh); 744 clear_bit(BH_JWrite, &bh->b_state); 745 J_ASSERT_BH(bh, buffer_jbddirty(bh)); 746 747 /* The metadata is now released for reuse, but we need 748 to remember it against this transaction so that when 749 we finally commit, we can do any checkpointing 750 required. */ 751 JBUFFER_TRACE(jh, "file as BJ_Forget"); 752 jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget); 753 /* Wake up any transactions which were waiting for this 754 IO to complete */ 755 wake_up_bit(&bh->b_state, BH_Unshadow); 756 JBUFFER_TRACE(jh, "brelse shadowed buffer"); 757 __brelse(bh); 758 } 759 760 J_ASSERT (commit_transaction->t_shadow_list == NULL); 761 762 jbd_debug(3, "JBD: commit phase 4\n"); 763 764 /* Here we wait for the revoke record and descriptor record buffers */ 765 wait_for_ctlbuf: 766 while (commit_transaction->t_log_list != NULL) { 767 struct buffer_head *bh; 768 769 jh = commit_transaction->t_log_list->b_tprev; 770 bh = jh2bh(jh); 771 if (buffer_locked(bh)) { 772 wait_on_buffer(bh); 773 goto wait_for_ctlbuf; 774 } 775 if (cond_resched()) 776 goto wait_for_ctlbuf; 777 778 if (unlikely(!buffer_uptodate(bh))) 779 err = -EIO; 780 781 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile"); 782 clear_buffer_jwrite(bh); 783 jbd2_journal_unfile_buffer(journal, jh); 784 jbd2_journal_put_journal_head(jh); 785 __brelse(bh); /* One for getblk */ 786 /* AKPM: bforget here */ 787 } 788 789 jbd_debug(3, "JBD: commit phase 5\n"); 790 791 if (!JBD2_HAS_INCOMPAT_FEATURE(journal, 792 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { 793 err = journal_submit_commit_record(journal, commit_transaction, 794 &cbh, crc32_sum); 795 if (err) 796 __jbd2_journal_abort_hard(journal); 797 } 798 if (!err && !is_journal_aborted(journal)) 799 err = journal_wait_on_commit_record(cbh); 800 801 if (err) 802 jbd2_journal_abort(journal, err); 803 804 /* End of a transaction! Finally, we can do checkpoint 805 processing: any buffers committed as a result of this 806 transaction can be removed from any checkpoint list it was on 807 before. */ 808 809 jbd_debug(3, "JBD: commit phase 6\n"); 810 811 J_ASSERT(list_empty(&commit_transaction->t_inode_list)); 812 J_ASSERT(commit_transaction->t_buffers == NULL); 813 J_ASSERT(commit_transaction->t_checkpoint_list == NULL); 814 J_ASSERT(commit_transaction->t_iobuf_list == NULL); 815 J_ASSERT(commit_transaction->t_shadow_list == NULL); 816 J_ASSERT(commit_transaction->t_log_list == NULL); 817 818 restart_loop: 819 /* 820 * As there are other places (journal_unmap_buffer()) adding buffers 821 * to this list we have to be careful and hold the j_list_lock. 822 */ 823 spin_lock(&journal->j_list_lock); 824 while (commit_transaction->t_forget) { 825 transaction_t *cp_transaction; 826 struct buffer_head *bh; 827 828 jh = commit_transaction->t_forget; 829 spin_unlock(&journal->j_list_lock); 830 bh = jh2bh(jh); 831 jbd_lock_bh_state(bh); 832 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction || 833 jh->b_transaction == journal->j_running_transaction); 834 835 /* 836 * If there is undo-protected committed data against 837 * this buffer, then we can remove it now. If it is a 838 * buffer needing such protection, the old frozen_data 839 * field now points to a committed version of the 840 * buffer, so rotate that field to the new committed 841 * data. 842 * 843 * Otherwise, we can just throw away the frozen data now. 844 */ 845 if (jh->b_committed_data) { 846 jbd2_free(jh->b_committed_data, bh->b_size); 847 jh->b_committed_data = NULL; 848 if (jh->b_frozen_data) { 849 jh->b_committed_data = jh->b_frozen_data; 850 jh->b_frozen_data = NULL; 851 } 852 } else if (jh->b_frozen_data) { 853 jbd2_free(jh->b_frozen_data, bh->b_size); 854 jh->b_frozen_data = NULL; 855 } 856 857 spin_lock(&journal->j_list_lock); 858 cp_transaction = jh->b_cp_transaction; 859 if (cp_transaction) { 860 JBUFFER_TRACE(jh, "remove from old cp transaction"); 861 cp_transaction->t_chp_stats.cs_dropped++; 862 __jbd2_journal_remove_checkpoint(jh); 863 } 864 865 /* Only re-checkpoint the buffer_head if it is marked 866 * dirty. If the buffer was added to the BJ_Forget list 867 * by jbd2_journal_forget, it may no longer be dirty and 868 * there's no point in keeping a checkpoint record for 869 * it. */ 870 871 /* A buffer which has been freed while still being 872 * journaled by a previous transaction may end up still 873 * being dirty here, but we want to avoid writing back 874 * that buffer in the future now that the last use has 875 * been committed. That's not only a performance gain, 876 * it also stops aliasing problems if the buffer is left 877 * behind for writeback and gets reallocated for another 878 * use in a different page. */ 879 if (buffer_freed(bh)) { 880 clear_buffer_freed(bh); 881 clear_buffer_jbddirty(bh); 882 } 883 884 if (buffer_jbddirty(bh)) { 885 JBUFFER_TRACE(jh, "add to new checkpointing trans"); 886 __jbd2_journal_insert_checkpoint(jh, commit_transaction); 887 JBUFFER_TRACE(jh, "refile for checkpoint writeback"); 888 __jbd2_journal_refile_buffer(jh); 889 jbd_unlock_bh_state(bh); 890 } else { 891 J_ASSERT_BH(bh, !buffer_dirty(bh)); 892 /* The buffer on BJ_Forget list and not jbddirty means 893 * it has been freed by this transaction and hence it 894 * could not have been reallocated until this 895 * transaction has committed. *BUT* it could be 896 * reallocated once we have written all the data to 897 * disk and before we process the buffer on BJ_Forget 898 * list. */ 899 JBUFFER_TRACE(jh, "refile or unfile freed buffer"); 900 __jbd2_journal_refile_buffer(jh); 901 if (!jh->b_transaction) { 902 jbd_unlock_bh_state(bh); 903 /* needs a brelse */ 904 jbd2_journal_remove_journal_head(bh); 905 release_buffer_page(bh); 906 } else 907 jbd_unlock_bh_state(bh); 908 } 909 cond_resched_lock(&journal->j_list_lock); 910 } 911 spin_unlock(&journal->j_list_lock); 912 /* 913 * This is a bit sleazy. We use j_list_lock to protect transition 914 * of a transaction into T_FINISHED state and calling 915 * __jbd2_journal_drop_transaction(). Otherwise we could race with 916 * other checkpointing code processing the transaction... 917 */ 918 spin_lock(&journal->j_state_lock); 919 spin_lock(&journal->j_list_lock); 920 /* 921 * Now recheck if some buffers did not get attached to the transaction 922 * while the lock was dropped... 923 */ 924 if (commit_transaction->t_forget) { 925 spin_unlock(&journal->j_list_lock); 926 spin_unlock(&journal->j_state_lock); 927 goto restart_loop; 928 } 929 930 /* Done with this transaction! */ 931 932 jbd_debug(3, "JBD: commit phase 7\n"); 933 934 J_ASSERT(commit_transaction->t_state == T_COMMIT); 935 936 commit_transaction->t_start = jiffies; 937 stats.u.run.rs_logging = jbd2_time_diff(stats.u.run.rs_logging, 938 commit_transaction->t_start); 939 940 /* 941 * File the transaction for history 942 */ 943 stats.ts_type = JBD2_STATS_RUN; 944 stats.ts_tid = commit_transaction->t_tid; 945 stats.u.run.rs_handle_count = commit_transaction->t_handle_count; 946 spin_lock(&journal->j_history_lock); 947 memcpy(journal->j_history + journal->j_history_cur, &stats, 948 sizeof(stats)); 949 if (++journal->j_history_cur == journal->j_history_max) 950 journal->j_history_cur = 0; 951 952 /* 953 * Calculate overall stats 954 */ 955 journal->j_stats.ts_tid++; 956 journal->j_stats.u.run.rs_wait += stats.u.run.rs_wait; 957 journal->j_stats.u.run.rs_running += stats.u.run.rs_running; 958 journal->j_stats.u.run.rs_locked += stats.u.run.rs_locked; 959 journal->j_stats.u.run.rs_flushing += stats.u.run.rs_flushing; 960 journal->j_stats.u.run.rs_logging += stats.u.run.rs_logging; 961 journal->j_stats.u.run.rs_handle_count += stats.u.run.rs_handle_count; 962 journal->j_stats.u.run.rs_blocks += stats.u.run.rs_blocks; 963 journal->j_stats.u.run.rs_blocks_logged += stats.u.run.rs_blocks_logged; 964 spin_unlock(&journal->j_history_lock); 965 966 commit_transaction->t_state = T_FINISHED; 967 J_ASSERT(commit_transaction == journal->j_committing_transaction); 968 journal->j_commit_sequence = commit_transaction->t_tid; 969 journal->j_committing_transaction = NULL; 970 spin_unlock(&journal->j_state_lock); 971 972 if (commit_transaction->t_checkpoint_list == NULL && 973 commit_transaction->t_checkpoint_io_list == NULL) { 974 __jbd2_journal_drop_transaction(journal, commit_transaction); 975 } else { 976 if (journal->j_checkpoint_transactions == NULL) { 977 journal->j_checkpoint_transactions = commit_transaction; 978 commit_transaction->t_cpnext = commit_transaction; 979 commit_transaction->t_cpprev = commit_transaction; 980 } else { 981 commit_transaction->t_cpnext = 982 journal->j_checkpoint_transactions; 983 commit_transaction->t_cpprev = 984 commit_transaction->t_cpnext->t_cpprev; 985 commit_transaction->t_cpnext->t_cpprev = 986 commit_transaction; 987 commit_transaction->t_cpprev->t_cpnext = 988 commit_transaction; 989 } 990 } 991 spin_unlock(&journal->j_list_lock); 992 993 jbd_debug(1, "JBD: commit %d complete, head %d\n", 994 journal->j_commit_sequence, journal->j_tail_sequence); 995 996 wake_up(&journal->j_wait_done_commit); 997 } 998