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 26 /* 27 * Default IO end handler for temporary BJ_IO buffer_heads. 28 */ 29 static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate) 30 { 31 BUFFER_TRACE(bh, ""); 32 if (uptodate) 33 set_buffer_uptodate(bh); 34 else 35 clear_buffer_uptodate(bh); 36 unlock_buffer(bh); 37 } 38 39 /* 40 * When an ext3-ordered file is truncated, it is possible that many pages are 41 * not sucessfully freed, because they are attached to a committing transaction. 42 * After the transaction commits, these pages are left on the LRU, with no 43 * ->mapping, and with attached buffers. These pages are trivially reclaimable 44 * by the VM, but their apparent absence upsets the VM accounting, and it makes 45 * the numbers in /proc/meminfo look odd. 46 * 47 * So here, we have a buffer which has just come off the forget list. Look to 48 * see if we can strip all buffers from the backing page. 49 * 50 * Called under lock_journal(), and possibly under journal_datalist_lock. The 51 * caller provided us with a ref against the buffer, and we drop that here. 52 */ 53 static void release_buffer_page(struct buffer_head *bh) 54 { 55 struct page *page; 56 57 if (buffer_dirty(bh)) 58 goto nope; 59 if (atomic_read(&bh->b_count) != 1) 60 goto nope; 61 page = bh->b_page; 62 if (!page) 63 goto nope; 64 if (page->mapping) 65 goto nope; 66 67 /* OK, it's a truncated page */ 68 if (TestSetPageLocked(page)) 69 goto nope; 70 71 page_cache_get(page); 72 __brelse(bh); 73 try_to_free_buffers(page); 74 unlock_page(page); 75 page_cache_release(page); 76 return; 77 78 nope: 79 __brelse(bh); 80 } 81 82 /* 83 * Try to acquire jbd_lock_bh_state() against the buffer, when j_list_lock is 84 * held. For ranking reasons we must trylock. If we lose, schedule away and 85 * return 0. j_list_lock is dropped in this case. 86 */ 87 static int inverted_lock(journal_t *journal, struct buffer_head *bh) 88 { 89 if (!jbd_trylock_bh_state(bh)) { 90 spin_unlock(&journal->j_list_lock); 91 schedule(); 92 return 0; 93 } 94 return 1; 95 } 96 97 /* 98 * Done it all: now submit the commit record. We should have 99 * cleaned up our previous buffers by now, so if we are in abort 100 * mode we can now just skip the rest of the journal write 101 * entirely. 102 * 103 * Returns 1 if the journal needs to be aborted or 0 on success 104 */ 105 static int journal_submit_commit_record(journal_t *journal, 106 transaction_t *commit_transaction, 107 struct buffer_head **cbh, 108 __u32 crc32_sum) 109 { 110 struct journal_head *descriptor; 111 struct commit_header *tmp; 112 struct buffer_head *bh; 113 int ret; 114 int barrier_done = 0; 115 116 if (is_journal_aborted(journal)) 117 return 0; 118 119 descriptor = jbd2_journal_get_descriptor_buffer(journal); 120 if (!descriptor) 121 return 1; 122 123 bh = jh2bh(descriptor); 124 125 tmp = (struct commit_header *)bh->b_data; 126 tmp->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER); 127 tmp->h_blocktype = cpu_to_be32(JBD2_COMMIT_BLOCK); 128 tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid); 129 130 if (JBD2_HAS_COMPAT_FEATURE(journal, 131 JBD2_FEATURE_COMPAT_CHECKSUM)) { 132 tmp->h_chksum_type = JBD2_CRC32_CHKSUM; 133 tmp->h_chksum_size = JBD2_CRC32_CHKSUM_SIZE; 134 tmp->h_chksum[0] = cpu_to_be32(crc32_sum); 135 } 136 137 JBUFFER_TRACE(descriptor, "submit commit block"); 138 lock_buffer(bh); 139 get_bh(bh); 140 set_buffer_dirty(bh); 141 set_buffer_uptodate(bh); 142 bh->b_end_io = journal_end_buffer_io_sync; 143 144 if (journal->j_flags & JBD2_BARRIER && 145 !JBD2_HAS_INCOMPAT_FEATURE(journal, 146 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { 147 set_buffer_ordered(bh); 148 barrier_done = 1; 149 } 150 ret = submit_bh(WRITE, bh); 151 if (barrier_done) 152 clear_buffer_ordered(bh); 153 154 /* is it possible for another commit to fail at roughly 155 * the same time as this one? If so, we don't want to 156 * trust the barrier flag in the super, but instead want 157 * to remember if we sent a barrier request 158 */ 159 if (ret == -EOPNOTSUPP && barrier_done) { 160 char b[BDEVNAME_SIZE]; 161 162 printk(KERN_WARNING 163 "JBD: barrier-based sync failed on %s - " 164 "disabling barriers\n", 165 bdevname(journal->j_dev, b)); 166 spin_lock(&journal->j_state_lock); 167 journal->j_flags &= ~JBD2_BARRIER; 168 spin_unlock(&journal->j_state_lock); 169 170 /* And try again, without the barrier */ 171 set_buffer_uptodate(bh); 172 set_buffer_dirty(bh); 173 ret = submit_bh(WRITE, bh); 174 } 175 *cbh = bh; 176 return ret; 177 } 178 179 /* 180 * This function along with journal_submit_commit_record 181 * allows to write the commit record asynchronously. 182 */ 183 static int journal_wait_on_commit_record(struct buffer_head *bh) 184 { 185 int ret = 0; 186 187 clear_buffer_dirty(bh); 188 wait_on_buffer(bh); 189 190 if (unlikely(!buffer_uptodate(bh))) 191 ret = -EIO; 192 put_bh(bh); /* One for getblk() */ 193 jbd2_journal_put_journal_head(bh2jh(bh)); 194 195 return ret; 196 } 197 198 /* 199 * Wait for all submitted IO to complete. 200 */ 201 static int journal_wait_on_locked_list(journal_t *journal, 202 transaction_t *commit_transaction) 203 { 204 int ret = 0; 205 struct journal_head *jh; 206 207 while (commit_transaction->t_locked_list) { 208 struct buffer_head *bh; 209 210 jh = commit_transaction->t_locked_list->b_tprev; 211 bh = jh2bh(jh); 212 get_bh(bh); 213 if (buffer_locked(bh)) { 214 spin_unlock(&journal->j_list_lock); 215 wait_on_buffer(bh); 216 if (unlikely(!buffer_uptodate(bh))) 217 ret = -EIO; 218 spin_lock(&journal->j_list_lock); 219 } 220 if (!inverted_lock(journal, bh)) { 221 put_bh(bh); 222 spin_lock(&journal->j_list_lock); 223 continue; 224 } 225 if (buffer_jbd(bh) && jh->b_jlist == BJ_Locked) { 226 __jbd2_journal_unfile_buffer(jh); 227 jbd_unlock_bh_state(bh); 228 jbd2_journal_remove_journal_head(bh); 229 put_bh(bh); 230 } else { 231 jbd_unlock_bh_state(bh); 232 } 233 put_bh(bh); 234 cond_resched_lock(&journal->j_list_lock); 235 } 236 return ret; 237 } 238 239 static void journal_do_submit_data(struct buffer_head **wbuf, int bufs) 240 { 241 int i; 242 243 for (i = 0; i < bufs; i++) { 244 wbuf[i]->b_end_io = end_buffer_write_sync; 245 /* We use-up our safety reference in submit_bh() */ 246 submit_bh(WRITE, wbuf[i]); 247 } 248 } 249 250 /* 251 * Submit all the data buffers to disk 252 */ 253 static void journal_submit_data_buffers(journal_t *journal, 254 transaction_t *commit_transaction) 255 { 256 struct journal_head *jh; 257 struct buffer_head *bh; 258 int locked; 259 int bufs = 0; 260 struct buffer_head **wbuf = journal->j_wbuf; 261 262 /* 263 * Whenever we unlock the journal and sleep, things can get added 264 * onto ->t_sync_datalist, so we have to keep looping back to 265 * write_out_data until we *know* that the list is empty. 266 * 267 * Cleanup any flushed data buffers from the data list. Even in 268 * abort mode, we want to flush this out as soon as possible. 269 */ 270 write_out_data: 271 cond_resched(); 272 spin_lock(&journal->j_list_lock); 273 274 while (commit_transaction->t_sync_datalist) { 275 jh = commit_transaction->t_sync_datalist; 276 bh = jh2bh(jh); 277 locked = 0; 278 279 /* Get reference just to make sure buffer does not disappear 280 * when we are forced to drop various locks */ 281 get_bh(bh); 282 /* If the buffer is dirty, we need to submit IO and hence 283 * we need the buffer lock. We try to lock the buffer without 284 * blocking. If we fail, we need to drop j_list_lock and do 285 * blocking lock_buffer(). 286 */ 287 if (buffer_dirty(bh)) { 288 if (test_set_buffer_locked(bh)) { 289 BUFFER_TRACE(bh, "needs blocking lock"); 290 spin_unlock(&journal->j_list_lock); 291 /* Write out all data to prevent deadlocks */ 292 journal_do_submit_data(wbuf, bufs); 293 bufs = 0; 294 lock_buffer(bh); 295 spin_lock(&journal->j_list_lock); 296 } 297 locked = 1; 298 } 299 /* We have to get bh_state lock. Again out of order, sigh. */ 300 if (!inverted_lock(journal, bh)) { 301 jbd_lock_bh_state(bh); 302 spin_lock(&journal->j_list_lock); 303 } 304 /* Someone already cleaned up the buffer? */ 305 if (!buffer_jbd(bh) 306 || jh->b_transaction != commit_transaction 307 || jh->b_jlist != BJ_SyncData) { 308 jbd_unlock_bh_state(bh); 309 if (locked) 310 unlock_buffer(bh); 311 BUFFER_TRACE(bh, "already cleaned up"); 312 put_bh(bh); 313 continue; 314 } 315 if (locked && test_clear_buffer_dirty(bh)) { 316 BUFFER_TRACE(bh, "needs writeout, adding to array"); 317 wbuf[bufs++] = bh; 318 __jbd2_journal_file_buffer(jh, commit_transaction, 319 BJ_Locked); 320 jbd_unlock_bh_state(bh); 321 if (bufs == journal->j_wbufsize) { 322 spin_unlock(&journal->j_list_lock); 323 journal_do_submit_data(wbuf, bufs); 324 bufs = 0; 325 goto write_out_data; 326 } 327 } else if (!locked && buffer_locked(bh)) { 328 __jbd2_journal_file_buffer(jh, commit_transaction, 329 BJ_Locked); 330 jbd_unlock_bh_state(bh); 331 put_bh(bh); 332 } else { 333 BUFFER_TRACE(bh, "writeout complete: unfile"); 334 __jbd2_journal_unfile_buffer(jh); 335 jbd_unlock_bh_state(bh); 336 if (locked) 337 unlock_buffer(bh); 338 jbd2_journal_remove_journal_head(bh); 339 /* Once for our safety reference, once for 340 * jbd2_journal_remove_journal_head() */ 341 put_bh(bh); 342 put_bh(bh); 343 } 344 345 if (need_resched() || spin_needbreak(&journal->j_list_lock)) { 346 spin_unlock(&journal->j_list_lock); 347 goto write_out_data; 348 } 349 } 350 spin_unlock(&journal->j_list_lock); 351 journal_do_submit_data(wbuf, bufs); 352 } 353 354 static __u32 jbd2_checksum_data(__u32 crc32_sum, struct buffer_head *bh) 355 { 356 struct page *page = bh->b_page; 357 char *addr; 358 __u32 checksum; 359 360 addr = kmap_atomic(page, KM_USER0); 361 checksum = crc32_be(crc32_sum, 362 (void *)(addr + offset_in_page(bh->b_data)), bh->b_size); 363 kunmap_atomic(addr, KM_USER0); 364 365 return checksum; 366 } 367 368 static void write_tag_block(int tag_bytes, journal_block_tag_t *tag, 369 unsigned long long block) 370 { 371 tag->t_blocknr = cpu_to_be32(block & (u32)~0); 372 if (tag_bytes > JBD2_TAG_SIZE32) 373 tag->t_blocknr_high = cpu_to_be32((block >> 31) >> 1); 374 } 375 376 /* 377 * jbd2_journal_commit_transaction 378 * 379 * The primary function for committing a transaction to the log. This 380 * function is called by the journal thread to begin a complete commit. 381 */ 382 void jbd2_journal_commit_transaction(journal_t *journal) 383 { 384 struct transaction_stats_s stats; 385 transaction_t *commit_transaction; 386 struct journal_head *jh, *new_jh, *descriptor; 387 struct buffer_head **wbuf = journal->j_wbuf; 388 int bufs; 389 int flags; 390 int err; 391 unsigned long long blocknr; 392 char *tagp = NULL; 393 journal_header_t *header; 394 journal_block_tag_t *tag = NULL; 395 int space_left = 0; 396 int first_tag = 0; 397 int tag_flag; 398 int i; 399 int tag_bytes = journal_tag_bytes(journal); 400 struct buffer_head *cbh = NULL; /* For transactional checksums */ 401 __u32 crc32_sum = ~0; 402 403 /* 404 * First job: lock down the current transaction and wait for 405 * all outstanding updates to complete. 406 */ 407 408 #ifdef COMMIT_STATS 409 spin_lock(&journal->j_list_lock); 410 summarise_journal_usage(journal); 411 spin_unlock(&journal->j_list_lock); 412 #endif 413 414 /* Do we need to erase the effects of a prior jbd2_journal_flush? */ 415 if (journal->j_flags & JBD2_FLUSHED) { 416 jbd_debug(3, "super block updated\n"); 417 jbd2_journal_update_superblock(journal, 1); 418 } else { 419 jbd_debug(3, "superblock not updated\n"); 420 } 421 422 J_ASSERT(journal->j_running_transaction != NULL); 423 J_ASSERT(journal->j_committing_transaction == NULL); 424 425 commit_transaction = journal->j_running_transaction; 426 J_ASSERT(commit_transaction->t_state == T_RUNNING); 427 428 jbd_debug(1, "JBD: starting commit of transaction %d\n", 429 commit_transaction->t_tid); 430 431 spin_lock(&journal->j_state_lock); 432 commit_transaction->t_state = T_LOCKED; 433 434 stats.u.run.rs_wait = commit_transaction->t_max_wait; 435 stats.u.run.rs_locked = jiffies; 436 stats.u.run.rs_running = jbd2_time_diff(commit_transaction->t_start, 437 stats.u.run.rs_locked); 438 439 spin_lock(&commit_transaction->t_handle_lock); 440 while (commit_transaction->t_updates) { 441 DEFINE_WAIT(wait); 442 443 prepare_to_wait(&journal->j_wait_updates, &wait, 444 TASK_UNINTERRUPTIBLE); 445 if (commit_transaction->t_updates) { 446 spin_unlock(&commit_transaction->t_handle_lock); 447 spin_unlock(&journal->j_state_lock); 448 schedule(); 449 spin_lock(&journal->j_state_lock); 450 spin_lock(&commit_transaction->t_handle_lock); 451 } 452 finish_wait(&journal->j_wait_updates, &wait); 453 } 454 spin_unlock(&commit_transaction->t_handle_lock); 455 456 J_ASSERT (commit_transaction->t_outstanding_credits <= 457 journal->j_max_transaction_buffers); 458 459 /* 460 * First thing we are allowed to do is to discard any remaining 461 * BJ_Reserved buffers. Note, it is _not_ permissible to assume 462 * that there are no such buffers: if a large filesystem 463 * operation like a truncate needs to split itself over multiple 464 * transactions, then it may try to do a jbd2_journal_restart() while 465 * there are still BJ_Reserved buffers outstanding. These must 466 * be released cleanly from the current transaction. 467 * 468 * In this case, the filesystem must still reserve write access 469 * again before modifying the buffer in the new transaction, but 470 * we do not require it to remember exactly which old buffers it 471 * has reserved. This is consistent with the existing behaviour 472 * that multiple jbd2_journal_get_write_access() calls to the same 473 * buffer are perfectly permissable. 474 */ 475 while (commit_transaction->t_reserved_list) { 476 jh = commit_transaction->t_reserved_list; 477 JBUFFER_TRACE(jh, "reserved, unused: refile"); 478 /* 479 * A jbd2_journal_get_undo_access()+jbd2_journal_release_buffer() may 480 * leave undo-committed data. 481 */ 482 if (jh->b_committed_data) { 483 struct buffer_head *bh = jh2bh(jh); 484 485 jbd_lock_bh_state(bh); 486 jbd2_free(jh->b_committed_data, bh->b_size); 487 jh->b_committed_data = NULL; 488 jbd_unlock_bh_state(bh); 489 } 490 jbd2_journal_refile_buffer(journal, jh); 491 } 492 493 /* 494 * Now try to drop any written-back buffers from the journal's 495 * checkpoint lists. We do this *before* commit because it potentially 496 * frees some memory 497 */ 498 spin_lock(&journal->j_list_lock); 499 __jbd2_journal_clean_checkpoint_list(journal); 500 spin_unlock(&journal->j_list_lock); 501 502 jbd_debug (3, "JBD: commit phase 1\n"); 503 504 /* 505 * Switch to a new revoke table. 506 */ 507 jbd2_journal_switch_revoke_table(journal); 508 509 stats.u.run.rs_flushing = jiffies; 510 stats.u.run.rs_locked = jbd2_time_diff(stats.u.run.rs_locked, 511 stats.u.run.rs_flushing); 512 513 commit_transaction->t_state = T_FLUSH; 514 journal->j_committing_transaction = commit_transaction; 515 journal->j_running_transaction = NULL; 516 commit_transaction->t_log_start = journal->j_head; 517 wake_up(&journal->j_wait_transaction_locked); 518 spin_unlock(&journal->j_state_lock); 519 520 jbd_debug (3, "JBD: commit phase 2\n"); 521 522 /* 523 * First, drop modified flag: all accesses to the buffers 524 * will be tracked for a new trasaction only -bzzz 525 */ 526 spin_lock(&journal->j_list_lock); 527 if (commit_transaction->t_buffers) { 528 new_jh = jh = commit_transaction->t_buffers->b_tnext; 529 do { 530 J_ASSERT_JH(new_jh, new_jh->b_modified == 1 || 531 new_jh->b_modified == 0); 532 new_jh->b_modified = 0; 533 new_jh = new_jh->b_tnext; 534 } while (new_jh != jh); 535 } 536 spin_unlock(&journal->j_list_lock); 537 538 /* 539 * Now start flushing things to disk, in the order they appear 540 * on the transaction lists. Data blocks go first. 541 */ 542 err = 0; 543 journal_submit_data_buffers(journal, commit_transaction); 544 545 /* 546 * Wait for all previously submitted IO to complete if commit 547 * record is to be written synchronously. 548 */ 549 spin_lock(&journal->j_list_lock); 550 if (!JBD2_HAS_INCOMPAT_FEATURE(journal, 551 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) 552 err = journal_wait_on_locked_list(journal, 553 commit_transaction); 554 555 spin_unlock(&journal->j_list_lock); 556 557 if (err) 558 jbd2_journal_abort(journal, err); 559 560 jbd2_journal_write_revoke_records(journal, commit_transaction); 561 562 jbd_debug(3, "JBD: commit phase 2\n"); 563 564 /* 565 * If we found any dirty or locked buffers, then we should have 566 * looped back up to the write_out_data label. If there weren't 567 * any then journal_clean_data_list should have wiped the list 568 * clean by now, so check that it is in fact empty. 569 */ 570 J_ASSERT (commit_transaction->t_sync_datalist == NULL); 571 572 jbd_debug (3, "JBD: commit phase 3\n"); 573 574 /* 575 * Way to go: we have now written out all of the data for a 576 * transaction! Now comes the tricky part: we need to write out 577 * metadata. Loop over the transaction's entire buffer list: 578 */ 579 commit_transaction->t_state = T_COMMIT; 580 581 stats.u.run.rs_logging = jiffies; 582 stats.u.run.rs_flushing = jbd2_time_diff(stats.u.run.rs_flushing, 583 stats.u.run.rs_logging); 584 stats.u.run.rs_blocks = commit_transaction->t_outstanding_credits; 585 stats.u.run.rs_blocks_logged = 0; 586 587 descriptor = NULL; 588 bufs = 0; 589 while (commit_transaction->t_buffers) { 590 591 /* Find the next buffer to be journaled... */ 592 593 jh = commit_transaction->t_buffers; 594 595 /* If we're in abort mode, we just un-journal the buffer and 596 release it for background writing. */ 597 598 if (is_journal_aborted(journal)) { 599 JBUFFER_TRACE(jh, "journal is aborting: refile"); 600 jbd2_journal_refile_buffer(journal, jh); 601 /* If that was the last one, we need to clean up 602 * any descriptor buffers which may have been 603 * already allocated, even if we are now 604 * aborting. */ 605 if (!commit_transaction->t_buffers) 606 goto start_journal_io; 607 continue; 608 } 609 610 /* Make sure we have a descriptor block in which to 611 record the metadata buffer. */ 612 613 if (!descriptor) { 614 struct buffer_head *bh; 615 616 J_ASSERT (bufs == 0); 617 618 jbd_debug(4, "JBD: get descriptor\n"); 619 620 descriptor = jbd2_journal_get_descriptor_buffer(journal); 621 if (!descriptor) { 622 jbd2_journal_abort(journal, -EIO); 623 continue; 624 } 625 626 bh = jh2bh(descriptor); 627 jbd_debug(4, "JBD: got buffer %llu (%p)\n", 628 (unsigned long long)bh->b_blocknr, bh->b_data); 629 header = (journal_header_t *)&bh->b_data[0]; 630 header->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER); 631 header->h_blocktype = cpu_to_be32(JBD2_DESCRIPTOR_BLOCK); 632 header->h_sequence = cpu_to_be32(commit_transaction->t_tid); 633 634 tagp = &bh->b_data[sizeof(journal_header_t)]; 635 space_left = bh->b_size - sizeof(journal_header_t); 636 first_tag = 1; 637 set_buffer_jwrite(bh); 638 set_buffer_dirty(bh); 639 wbuf[bufs++] = bh; 640 641 /* Record it so that we can wait for IO 642 completion later */ 643 BUFFER_TRACE(bh, "ph3: file as descriptor"); 644 jbd2_journal_file_buffer(descriptor, commit_transaction, 645 BJ_LogCtl); 646 } 647 648 /* Where is the buffer to be written? */ 649 650 err = jbd2_journal_next_log_block(journal, &blocknr); 651 /* If the block mapping failed, just abandon the buffer 652 and repeat this loop: we'll fall into the 653 refile-on-abort condition above. */ 654 if (err) { 655 jbd2_journal_abort(journal, err); 656 continue; 657 } 658 659 /* 660 * start_this_handle() uses t_outstanding_credits to determine 661 * the free space in the log, but this counter is changed 662 * by jbd2_journal_next_log_block() also. 663 */ 664 commit_transaction->t_outstanding_credits--; 665 666 /* Bump b_count to prevent truncate from stumbling over 667 the shadowed buffer! @@@ This can go if we ever get 668 rid of the BJ_IO/BJ_Shadow pairing of buffers. */ 669 atomic_inc(&jh2bh(jh)->b_count); 670 671 /* Make a temporary IO buffer with which to write it out 672 (this will requeue both the metadata buffer and the 673 temporary IO buffer). new_bh goes on BJ_IO*/ 674 675 set_bit(BH_JWrite, &jh2bh(jh)->b_state); 676 /* 677 * akpm: jbd2_journal_write_metadata_buffer() sets 678 * new_bh->b_transaction to commit_transaction. 679 * We need to clean this up before we release new_bh 680 * (which is of type BJ_IO) 681 */ 682 JBUFFER_TRACE(jh, "ph3: write metadata"); 683 flags = jbd2_journal_write_metadata_buffer(commit_transaction, 684 jh, &new_jh, blocknr); 685 set_bit(BH_JWrite, &jh2bh(new_jh)->b_state); 686 wbuf[bufs++] = jh2bh(new_jh); 687 688 /* Record the new block's tag in the current descriptor 689 buffer */ 690 691 tag_flag = 0; 692 if (flags & 1) 693 tag_flag |= JBD2_FLAG_ESCAPE; 694 if (!first_tag) 695 tag_flag |= JBD2_FLAG_SAME_UUID; 696 697 tag = (journal_block_tag_t *) tagp; 698 write_tag_block(tag_bytes, tag, jh2bh(jh)->b_blocknr); 699 tag->t_flags = cpu_to_be32(tag_flag); 700 tagp += tag_bytes; 701 space_left -= tag_bytes; 702 703 if (first_tag) { 704 memcpy (tagp, journal->j_uuid, 16); 705 tagp += 16; 706 space_left -= 16; 707 first_tag = 0; 708 } 709 710 /* If there's no more to do, or if the descriptor is full, 711 let the IO rip! */ 712 713 if (bufs == journal->j_wbufsize || 714 commit_transaction->t_buffers == NULL || 715 space_left < tag_bytes + 16) { 716 717 jbd_debug(4, "JBD: Submit %d IOs\n", bufs); 718 719 /* Write an end-of-descriptor marker before 720 submitting the IOs. "tag" still points to 721 the last tag we set up. */ 722 723 tag->t_flags |= cpu_to_be32(JBD2_FLAG_LAST_TAG); 724 725 start_journal_io: 726 for (i = 0; i < bufs; i++) { 727 struct buffer_head *bh = wbuf[i]; 728 /* 729 * Compute checksum. 730 */ 731 if (JBD2_HAS_COMPAT_FEATURE(journal, 732 JBD2_FEATURE_COMPAT_CHECKSUM)) { 733 crc32_sum = 734 jbd2_checksum_data(crc32_sum, bh); 735 } 736 737 lock_buffer(bh); 738 clear_buffer_dirty(bh); 739 set_buffer_uptodate(bh); 740 bh->b_end_io = journal_end_buffer_io_sync; 741 submit_bh(WRITE, bh); 742 } 743 cond_resched(); 744 stats.u.run.rs_blocks_logged += bufs; 745 746 /* Force a new descriptor to be generated next 747 time round the loop. */ 748 descriptor = NULL; 749 bufs = 0; 750 } 751 } 752 753 /* Done it all: now write the commit record asynchronously. */ 754 755 if (JBD2_HAS_INCOMPAT_FEATURE(journal, 756 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { 757 err = journal_submit_commit_record(journal, commit_transaction, 758 &cbh, crc32_sum); 759 if (err) 760 __jbd2_journal_abort_hard(journal); 761 762 spin_lock(&journal->j_list_lock); 763 err = journal_wait_on_locked_list(journal, 764 commit_transaction); 765 spin_unlock(&journal->j_list_lock); 766 if (err) 767 __jbd2_journal_abort_hard(journal); 768 } 769 770 /* Lo and behold: we have just managed to send a transaction to 771 the log. Before we can commit it, wait for the IO so far to 772 complete. Control buffers being written are on the 773 transaction's t_log_list queue, and metadata buffers are on 774 the t_iobuf_list queue. 775 776 Wait for the buffers in reverse order. That way we are 777 less likely to be woken up until all IOs have completed, and 778 so we incur less scheduling load. 779 */ 780 781 jbd_debug(3, "JBD: commit phase 4\n"); 782 783 /* 784 * akpm: these are BJ_IO, and j_list_lock is not needed. 785 * See __journal_try_to_free_buffer. 786 */ 787 wait_for_iobuf: 788 while (commit_transaction->t_iobuf_list != NULL) { 789 struct buffer_head *bh; 790 791 jh = commit_transaction->t_iobuf_list->b_tprev; 792 bh = jh2bh(jh); 793 if (buffer_locked(bh)) { 794 wait_on_buffer(bh); 795 goto wait_for_iobuf; 796 } 797 if (cond_resched()) 798 goto wait_for_iobuf; 799 800 if (unlikely(!buffer_uptodate(bh))) 801 err = -EIO; 802 803 clear_buffer_jwrite(bh); 804 805 JBUFFER_TRACE(jh, "ph4: unfile after journal write"); 806 jbd2_journal_unfile_buffer(journal, jh); 807 808 /* 809 * ->t_iobuf_list should contain only dummy buffer_heads 810 * which were created by jbd2_journal_write_metadata_buffer(). 811 */ 812 BUFFER_TRACE(bh, "dumping temporary bh"); 813 jbd2_journal_put_journal_head(jh); 814 __brelse(bh); 815 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0); 816 free_buffer_head(bh); 817 818 /* We also have to unlock and free the corresponding 819 shadowed buffer */ 820 jh = commit_transaction->t_shadow_list->b_tprev; 821 bh = jh2bh(jh); 822 clear_bit(BH_JWrite, &bh->b_state); 823 J_ASSERT_BH(bh, buffer_jbddirty(bh)); 824 825 /* The metadata is now released for reuse, but we need 826 to remember it against this transaction so that when 827 we finally commit, we can do any checkpointing 828 required. */ 829 JBUFFER_TRACE(jh, "file as BJ_Forget"); 830 jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget); 831 /* Wake up any transactions which were waiting for this 832 IO to complete */ 833 wake_up_bit(&bh->b_state, BH_Unshadow); 834 JBUFFER_TRACE(jh, "brelse shadowed buffer"); 835 __brelse(bh); 836 } 837 838 J_ASSERT (commit_transaction->t_shadow_list == NULL); 839 840 jbd_debug(3, "JBD: commit phase 5\n"); 841 842 /* Here we wait for the revoke record and descriptor record buffers */ 843 wait_for_ctlbuf: 844 while (commit_transaction->t_log_list != NULL) { 845 struct buffer_head *bh; 846 847 jh = commit_transaction->t_log_list->b_tprev; 848 bh = jh2bh(jh); 849 if (buffer_locked(bh)) { 850 wait_on_buffer(bh); 851 goto wait_for_ctlbuf; 852 } 853 if (cond_resched()) 854 goto wait_for_ctlbuf; 855 856 if (unlikely(!buffer_uptodate(bh))) 857 err = -EIO; 858 859 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile"); 860 clear_buffer_jwrite(bh); 861 jbd2_journal_unfile_buffer(journal, jh); 862 jbd2_journal_put_journal_head(jh); 863 __brelse(bh); /* One for getblk */ 864 /* AKPM: bforget here */ 865 } 866 867 jbd_debug(3, "JBD: commit phase 6\n"); 868 869 if (!JBD2_HAS_INCOMPAT_FEATURE(journal, 870 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { 871 err = journal_submit_commit_record(journal, commit_transaction, 872 &cbh, crc32_sum); 873 if (err) 874 __jbd2_journal_abort_hard(journal); 875 } 876 if (!err && !is_journal_aborted(journal)) 877 err = journal_wait_on_commit_record(cbh); 878 879 if (err) 880 jbd2_journal_abort(journal, err); 881 882 /* End of a transaction! Finally, we can do checkpoint 883 processing: any buffers committed as a result of this 884 transaction can be removed from any checkpoint list it was on 885 before. */ 886 887 jbd_debug(3, "JBD: commit phase 7\n"); 888 889 J_ASSERT(commit_transaction->t_sync_datalist == NULL); 890 J_ASSERT(commit_transaction->t_buffers == NULL); 891 J_ASSERT(commit_transaction->t_checkpoint_list == NULL); 892 J_ASSERT(commit_transaction->t_iobuf_list == NULL); 893 J_ASSERT(commit_transaction->t_shadow_list == NULL); 894 J_ASSERT(commit_transaction->t_log_list == NULL); 895 896 restart_loop: 897 /* 898 * As there are other places (journal_unmap_buffer()) adding buffers 899 * to this list we have to be careful and hold the j_list_lock. 900 */ 901 spin_lock(&journal->j_list_lock); 902 while (commit_transaction->t_forget) { 903 transaction_t *cp_transaction; 904 struct buffer_head *bh; 905 906 jh = commit_transaction->t_forget; 907 spin_unlock(&journal->j_list_lock); 908 bh = jh2bh(jh); 909 jbd_lock_bh_state(bh); 910 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction || 911 jh->b_transaction == journal->j_running_transaction); 912 913 /* 914 * If there is undo-protected committed data against 915 * this buffer, then we can remove it now. If it is a 916 * buffer needing such protection, the old frozen_data 917 * field now points to a committed version of the 918 * buffer, so rotate that field to the new committed 919 * data. 920 * 921 * Otherwise, we can just throw away the frozen data now. 922 */ 923 if (jh->b_committed_data) { 924 jbd2_free(jh->b_committed_data, bh->b_size); 925 jh->b_committed_data = NULL; 926 if (jh->b_frozen_data) { 927 jh->b_committed_data = jh->b_frozen_data; 928 jh->b_frozen_data = NULL; 929 } 930 } else if (jh->b_frozen_data) { 931 jbd2_free(jh->b_frozen_data, bh->b_size); 932 jh->b_frozen_data = NULL; 933 } 934 935 spin_lock(&journal->j_list_lock); 936 cp_transaction = jh->b_cp_transaction; 937 if (cp_transaction) { 938 JBUFFER_TRACE(jh, "remove from old cp transaction"); 939 cp_transaction->t_chp_stats.cs_dropped++; 940 __jbd2_journal_remove_checkpoint(jh); 941 } 942 943 /* Only re-checkpoint the buffer_head if it is marked 944 * dirty. If the buffer was added to the BJ_Forget list 945 * by jbd2_journal_forget, it may no longer be dirty and 946 * there's no point in keeping a checkpoint record for 947 * it. */ 948 949 /* A buffer which has been freed while still being 950 * journaled by a previous transaction may end up still 951 * being dirty here, but we want to avoid writing back 952 * that buffer in the future now that the last use has 953 * been committed. That's not only a performance gain, 954 * it also stops aliasing problems if the buffer is left 955 * behind for writeback and gets reallocated for another 956 * use in a different page. */ 957 if (buffer_freed(bh)) { 958 clear_buffer_freed(bh); 959 clear_buffer_jbddirty(bh); 960 } 961 962 if (buffer_jbddirty(bh)) { 963 JBUFFER_TRACE(jh, "add to new checkpointing trans"); 964 __jbd2_journal_insert_checkpoint(jh, commit_transaction); 965 JBUFFER_TRACE(jh, "refile for checkpoint writeback"); 966 __jbd2_journal_refile_buffer(jh); 967 jbd_unlock_bh_state(bh); 968 } else { 969 J_ASSERT_BH(bh, !buffer_dirty(bh)); 970 /* The buffer on BJ_Forget list and not jbddirty means 971 * it has been freed by this transaction and hence it 972 * could not have been reallocated until this 973 * transaction has committed. *BUT* it could be 974 * reallocated once we have written all the data to 975 * disk and before we process the buffer on BJ_Forget 976 * list. */ 977 JBUFFER_TRACE(jh, "refile or unfile freed buffer"); 978 __jbd2_journal_refile_buffer(jh); 979 if (!jh->b_transaction) { 980 jbd_unlock_bh_state(bh); 981 /* needs a brelse */ 982 jbd2_journal_remove_journal_head(bh); 983 release_buffer_page(bh); 984 } else 985 jbd_unlock_bh_state(bh); 986 } 987 cond_resched_lock(&journal->j_list_lock); 988 } 989 spin_unlock(&journal->j_list_lock); 990 /* 991 * This is a bit sleazy. We use j_list_lock to protect transition 992 * of a transaction into T_FINISHED state and calling 993 * __jbd2_journal_drop_transaction(). Otherwise we could race with 994 * other checkpointing code processing the transaction... 995 */ 996 spin_lock(&journal->j_state_lock); 997 spin_lock(&journal->j_list_lock); 998 /* 999 * Now recheck if some buffers did not get attached to the transaction 1000 * while the lock was dropped... 1001 */ 1002 if (commit_transaction->t_forget) { 1003 spin_unlock(&journal->j_list_lock); 1004 spin_unlock(&journal->j_state_lock); 1005 goto restart_loop; 1006 } 1007 1008 /* Done with this transaction! */ 1009 1010 jbd_debug(3, "JBD: commit phase 8\n"); 1011 1012 J_ASSERT(commit_transaction->t_state == T_COMMIT); 1013 1014 commit_transaction->t_start = jiffies; 1015 stats.u.run.rs_logging = jbd2_time_diff(stats.u.run.rs_logging, 1016 commit_transaction->t_start); 1017 1018 /* 1019 * File the transaction for history 1020 */ 1021 stats.ts_type = JBD2_STATS_RUN; 1022 stats.ts_tid = commit_transaction->t_tid; 1023 stats.u.run.rs_handle_count = commit_transaction->t_handle_count; 1024 spin_lock(&journal->j_history_lock); 1025 memcpy(journal->j_history + journal->j_history_cur, &stats, 1026 sizeof(stats)); 1027 if (++journal->j_history_cur == journal->j_history_max) 1028 journal->j_history_cur = 0; 1029 1030 /* 1031 * Calculate overall stats 1032 */ 1033 journal->j_stats.ts_tid++; 1034 journal->j_stats.u.run.rs_wait += stats.u.run.rs_wait; 1035 journal->j_stats.u.run.rs_running += stats.u.run.rs_running; 1036 journal->j_stats.u.run.rs_locked += stats.u.run.rs_locked; 1037 journal->j_stats.u.run.rs_flushing += stats.u.run.rs_flushing; 1038 journal->j_stats.u.run.rs_logging += stats.u.run.rs_logging; 1039 journal->j_stats.u.run.rs_handle_count += stats.u.run.rs_handle_count; 1040 journal->j_stats.u.run.rs_blocks += stats.u.run.rs_blocks; 1041 journal->j_stats.u.run.rs_blocks_logged += stats.u.run.rs_blocks_logged; 1042 spin_unlock(&journal->j_history_lock); 1043 1044 commit_transaction->t_state = T_FINISHED; 1045 J_ASSERT(commit_transaction == journal->j_committing_transaction); 1046 journal->j_commit_sequence = commit_transaction->t_tid; 1047 journal->j_committing_transaction = NULL; 1048 spin_unlock(&journal->j_state_lock); 1049 1050 if (commit_transaction->t_checkpoint_list == NULL && 1051 commit_transaction->t_checkpoint_io_list == NULL) { 1052 __jbd2_journal_drop_transaction(journal, commit_transaction); 1053 } else { 1054 if (journal->j_checkpoint_transactions == NULL) { 1055 journal->j_checkpoint_transactions = commit_transaction; 1056 commit_transaction->t_cpnext = commit_transaction; 1057 commit_transaction->t_cpprev = commit_transaction; 1058 } else { 1059 commit_transaction->t_cpnext = 1060 journal->j_checkpoint_transactions; 1061 commit_transaction->t_cpprev = 1062 commit_transaction->t_cpnext->t_cpprev; 1063 commit_transaction->t_cpnext->t_cpprev = 1064 commit_transaction; 1065 commit_transaction->t_cpprev->t_cpnext = 1066 commit_transaction; 1067 } 1068 } 1069 spin_unlock(&journal->j_list_lock); 1070 1071 jbd_debug(1, "JBD: commit %d complete, head %d\n", 1072 journal->j_commit_sequence, journal->j_tail_sequence); 1073 1074 wake_up(&journal->j_wait_done_commit); 1075 } 1076