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 * Now start flushing things to disk, in the order they appear 524 * on the transaction lists. Data blocks go first. 525 */ 526 err = 0; 527 journal_submit_data_buffers(journal, commit_transaction); 528 529 /* 530 * Wait for all previously submitted IO to complete if commit 531 * record is to be written synchronously. 532 */ 533 spin_lock(&journal->j_list_lock); 534 if (!JBD2_HAS_INCOMPAT_FEATURE(journal, 535 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) 536 err = journal_wait_on_locked_list(journal, 537 commit_transaction); 538 539 spin_unlock(&journal->j_list_lock); 540 541 if (err) 542 jbd2_journal_abort(journal, err); 543 544 jbd2_journal_write_revoke_records(journal, commit_transaction); 545 546 jbd_debug(3, "JBD: commit phase 2\n"); 547 548 /* 549 * If we found any dirty or locked buffers, then we should have 550 * looped back up to the write_out_data label. If there weren't 551 * any then journal_clean_data_list should have wiped the list 552 * clean by now, so check that it is in fact empty. 553 */ 554 J_ASSERT (commit_transaction->t_sync_datalist == NULL); 555 556 jbd_debug (3, "JBD: commit phase 3\n"); 557 558 /* 559 * Way to go: we have now written out all of the data for a 560 * transaction! Now comes the tricky part: we need to write out 561 * metadata. Loop over the transaction's entire buffer list: 562 */ 563 commit_transaction->t_state = T_COMMIT; 564 565 stats.u.run.rs_logging = jiffies; 566 stats.u.run.rs_flushing = jbd2_time_diff(stats.u.run.rs_flushing, 567 stats.u.run.rs_logging); 568 stats.u.run.rs_blocks = commit_transaction->t_outstanding_credits; 569 stats.u.run.rs_blocks_logged = 0; 570 571 J_ASSERT(commit_transaction->t_nr_buffers <= 572 commit_transaction->t_outstanding_credits); 573 574 descriptor = NULL; 575 bufs = 0; 576 while (commit_transaction->t_buffers) { 577 578 /* Find the next buffer to be journaled... */ 579 580 jh = commit_transaction->t_buffers; 581 582 /* If we're in abort mode, we just un-journal the buffer and 583 release it for background writing. */ 584 585 if (is_journal_aborted(journal)) { 586 JBUFFER_TRACE(jh, "journal is aborting: refile"); 587 jbd2_journal_refile_buffer(journal, jh); 588 /* If that was the last one, we need to clean up 589 * any descriptor buffers which may have been 590 * already allocated, even if we are now 591 * aborting. */ 592 if (!commit_transaction->t_buffers) 593 goto start_journal_io; 594 continue; 595 } 596 597 /* Make sure we have a descriptor block in which to 598 record the metadata buffer. */ 599 600 if (!descriptor) { 601 struct buffer_head *bh; 602 603 J_ASSERT (bufs == 0); 604 605 jbd_debug(4, "JBD: get descriptor\n"); 606 607 descriptor = jbd2_journal_get_descriptor_buffer(journal); 608 if (!descriptor) { 609 jbd2_journal_abort(journal, -EIO); 610 continue; 611 } 612 613 bh = jh2bh(descriptor); 614 jbd_debug(4, "JBD: got buffer %llu (%p)\n", 615 (unsigned long long)bh->b_blocknr, bh->b_data); 616 header = (journal_header_t *)&bh->b_data[0]; 617 header->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER); 618 header->h_blocktype = cpu_to_be32(JBD2_DESCRIPTOR_BLOCK); 619 header->h_sequence = cpu_to_be32(commit_transaction->t_tid); 620 621 tagp = &bh->b_data[sizeof(journal_header_t)]; 622 space_left = bh->b_size - sizeof(journal_header_t); 623 first_tag = 1; 624 set_buffer_jwrite(bh); 625 set_buffer_dirty(bh); 626 wbuf[bufs++] = bh; 627 628 /* Record it so that we can wait for IO 629 completion later */ 630 BUFFER_TRACE(bh, "ph3: file as descriptor"); 631 jbd2_journal_file_buffer(descriptor, commit_transaction, 632 BJ_LogCtl); 633 } 634 635 /* Where is the buffer to be written? */ 636 637 err = jbd2_journal_next_log_block(journal, &blocknr); 638 /* If the block mapping failed, just abandon the buffer 639 and repeat this loop: we'll fall into the 640 refile-on-abort condition above. */ 641 if (err) { 642 jbd2_journal_abort(journal, err); 643 continue; 644 } 645 646 /* 647 * start_this_handle() uses t_outstanding_credits to determine 648 * the free space in the log, but this counter is changed 649 * by jbd2_journal_next_log_block() also. 650 */ 651 commit_transaction->t_outstanding_credits--; 652 653 /* Bump b_count to prevent truncate from stumbling over 654 the shadowed buffer! @@@ This can go if we ever get 655 rid of the BJ_IO/BJ_Shadow pairing of buffers. */ 656 atomic_inc(&jh2bh(jh)->b_count); 657 658 /* Make a temporary IO buffer with which to write it out 659 (this will requeue both the metadata buffer and the 660 temporary IO buffer). new_bh goes on BJ_IO*/ 661 662 set_bit(BH_JWrite, &jh2bh(jh)->b_state); 663 /* 664 * akpm: jbd2_journal_write_metadata_buffer() sets 665 * new_bh->b_transaction to commit_transaction. 666 * We need to clean this up before we release new_bh 667 * (which is of type BJ_IO) 668 */ 669 JBUFFER_TRACE(jh, "ph3: write metadata"); 670 flags = jbd2_journal_write_metadata_buffer(commit_transaction, 671 jh, &new_jh, blocknr); 672 set_bit(BH_JWrite, &jh2bh(new_jh)->b_state); 673 wbuf[bufs++] = jh2bh(new_jh); 674 675 /* Record the new block's tag in the current descriptor 676 buffer */ 677 678 tag_flag = 0; 679 if (flags & 1) 680 tag_flag |= JBD2_FLAG_ESCAPE; 681 if (!first_tag) 682 tag_flag |= JBD2_FLAG_SAME_UUID; 683 684 tag = (journal_block_tag_t *) tagp; 685 write_tag_block(tag_bytes, tag, jh2bh(jh)->b_blocknr); 686 tag->t_flags = cpu_to_be32(tag_flag); 687 tagp += tag_bytes; 688 space_left -= tag_bytes; 689 690 if (first_tag) { 691 memcpy (tagp, journal->j_uuid, 16); 692 tagp += 16; 693 space_left -= 16; 694 first_tag = 0; 695 } 696 697 /* If there's no more to do, or if the descriptor is full, 698 let the IO rip! */ 699 700 if (bufs == journal->j_wbufsize || 701 commit_transaction->t_buffers == NULL || 702 space_left < tag_bytes + 16) { 703 704 jbd_debug(4, "JBD: Submit %d IOs\n", bufs); 705 706 /* Write an end-of-descriptor marker before 707 submitting the IOs. "tag" still points to 708 the last tag we set up. */ 709 710 tag->t_flags |= cpu_to_be32(JBD2_FLAG_LAST_TAG); 711 712 start_journal_io: 713 for (i = 0; i < bufs; i++) { 714 struct buffer_head *bh = wbuf[i]; 715 /* 716 * Compute checksum. 717 */ 718 if (JBD2_HAS_COMPAT_FEATURE(journal, 719 JBD2_FEATURE_COMPAT_CHECKSUM)) { 720 crc32_sum = 721 jbd2_checksum_data(crc32_sum, bh); 722 } 723 724 lock_buffer(bh); 725 clear_buffer_dirty(bh); 726 set_buffer_uptodate(bh); 727 bh->b_end_io = journal_end_buffer_io_sync; 728 submit_bh(WRITE, bh); 729 } 730 cond_resched(); 731 stats.u.run.rs_blocks_logged += bufs; 732 733 /* Force a new descriptor to be generated next 734 time round the loop. */ 735 descriptor = NULL; 736 bufs = 0; 737 } 738 } 739 740 /* Done it all: now write the commit record asynchronously. */ 741 742 if (JBD2_HAS_INCOMPAT_FEATURE(journal, 743 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { 744 err = journal_submit_commit_record(journal, commit_transaction, 745 &cbh, crc32_sum); 746 if (err) 747 __jbd2_journal_abort_hard(journal); 748 749 spin_lock(&journal->j_list_lock); 750 err = journal_wait_on_locked_list(journal, 751 commit_transaction); 752 spin_unlock(&journal->j_list_lock); 753 if (err) 754 __jbd2_journal_abort_hard(journal); 755 } 756 757 /* Lo and behold: we have just managed to send a transaction to 758 the log. Before we can commit it, wait for the IO so far to 759 complete. Control buffers being written are on the 760 transaction's t_log_list queue, and metadata buffers are on 761 the t_iobuf_list queue. 762 763 Wait for the buffers in reverse order. That way we are 764 less likely to be woken up until all IOs have completed, and 765 so we incur less scheduling load. 766 */ 767 768 jbd_debug(3, "JBD: commit phase 4\n"); 769 770 /* 771 * akpm: these are BJ_IO, and j_list_lock is not needed. 772 * See __journal_try_to_free_buffer. 773 */ 774 wait_for_iobuf: 775 while (commit_transaction->t_iobuf_list != NULL) { 776 struct buffer_head *bh; 777 778 jh = commit_transaction->t_iobuf_list->b_tprev; 779 bh = jh2bh(jh); 780 if (buffer_locked(bh)) { 781 wait_on_buffer(bh); 782 goto wait_for_iobuf; 783 } 784 if (cond_resched()) 785 goto wait_for_iobuf; 786 787 if (unlikely(!buffer_uptodate(bh))) 788 err = -EIO; 789 790 clear_buffer_jwrite(bh); 791 792 JBUFFER_TRACE(jh, "ph4: unfile after journal write"); 793 jbd2_journal_unfile_buffer(journal, jh); 794 795 /* 796 * ->t_iobuf_list should contain only dummy buffer_heads 797 * which were created by jbd2_journal_write_metadata_buffer(). 798 */ 799 BUFFER_TRACE(bh, "dumping temporary bh"); 800 jbd2_journal_put_journal_head(jh); 801 __brelse(bh); 802 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0); 803 free_buffer_head(bh); 804 805 /* We also have to unlock and free the corresponding 806 shadowed buffer */ 807 jh = commit_transaction->t_shadow_list->b_tprev; 808 bh = jh2bh(jh); 809 clear_bit(BH_JWrite, &bh->b_state); 810 J_ASSERT_BH(bh, buffer_jbddirty(bh)); 811 812 /* The metadata is now released for reuse, but we need 813 to remember it against this transaction so that when 814 we finally commit, we can do any checkpointing 815 required. */ 816 JBUFFER_TRACE(jh, "file as BJ_Forget"); 817 jbd2_journal_file_buffer(jh, commit_transaction, BJ_Forget); 818 /* Wake up any transactions which were waiting for this 819 IO to complete */ 820 wake_up_bit(&bh->b_state, BH_Unshadow); 821 JBUFFER_TRACE(jh, "brelse shadowed buffer"); 822 __brelse(bh); 823 } 824 825 J_ASSERT (commit_transaction->t_shadow_list == NULL); 826 827 jbd_debug(3, "JBD: commit phase 5\n"); 828 829 /* Here we wait for the revoke record and descriptor record buffers */ 830 wait_for_ctlbuf: 831 while (commit_transaction->t_log_list != NULL) { 832 struct buffer_head *bh; 833 834 jh = commit_transaction->t_log_list->b_tprev; 835 bh = jh2bh(jh); 836 if (buffer_locked(bh)) { 837 wait_on_buffer(bh); 838 goto wait_for_ctlbuf; 839 } 840 if (cond_resched()) 841 goto wait_for_ctlbuf; 842 843 if (unlikely(!buffer_uptodate(bh))) 844 err = -EIO; 845 846 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile"); 847 clear_buffer_jwrite(bh); 848 jbd2_journal_unfile_buffer(journal, jh); 849 jbd2_journal_put_journal_head(jh); 850 __brelse(bh); /* One for getblk */ 851 /* AKPM: bforget here */ 852 } 853 854 jbd_debug(3, "JBD: commit phase 6\n"); 855 856 if (!JBD2_HAS_INCOMPAT_FEATURE(journal, 857 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { 858 err = journal_submit_commit_record(journal, commit_transaction, 859 &cbh, crc32_sum); 860 if (err) 861 __jbd2_journal_abort_hard(journal); 862 } 863 if (!err && !is_journal_aborted(journal)) 864 err = journal_wait_on_commit_record(cbh); 865 866 if (err) 867 jbd2_journal_abort(journal, err); 868 869 /* End of a transaction! Finally, we can do checkpoint 870 processing: any buffers committed as a result of this 871 transaction can be removed from any checkpoint list it was on 872 before. */ 873 874 jbd_debug(3, "JBD: commit phase 7\n"); 875 876 J_ASSERT(commit_transaction->t_sync_datalist == NULL); 877 J_ASSERT(commit_transaction->t_buffers == NULL); 878 J_ASSERT(commit_transaction->t_checkpoint_list == NULL); 879 J_ASSERT(commit_transaction->t_iobuf_list == NULL); 880 J_ASSERT(commit_transaction->t_shadow_list == NULL); 881 J_ASSERT(commit_transaction->t_log_list == NULL); 882 883 restart_loop: 884 /* 885 * As there are other places (journal_unmap_buffer()) adding buffers 886 * to this list we have to be careful and hold the j_list_lock. 887 */ 888 spin_lock(&journal->j_list_lock); 889 while (commit_transaction->t_forget) { 890 transaction_t *cp_transaction; 891 struct buffer_head *bh; 892 893 jh = commit_transaction->t_forget; 894 spin_unlock(&journal->j_list_lock); 895 bh = jh2bh(jh); 896 jbd_lock_bh_state(bh); 897 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction || 898 jh->b_transaction == journal->j_running_transaction); 899 900 /* 901 * If there is undo-protected committed data against 902 * this buffer, then we can remove it now. If it is a 903 * buffer needing such protection, the old frozen_data 904 * field now points to a committed version of the 905 * buffer, so rotate that field to the new committed 906 * data. 907 * 908 * Otherwise, we can just throw away the frozen data now. 909 */ 910 if (jh->b_committed_data) { 911 jbd2_free(jh->b_committed_data, bh->b_size); 912 jh->b_committed_data = NULL; 913 if (jh->b_frozen_data) { 914 jh->b_committed_data = jh->b_frozen_data; 915 jh->b_frozen_data = NULL; 916 } 917 } else if (jh->b_frozen_data) { 918 jbd2_free(jh->b_frozen_data, bh->b_size); 919 jh->b_frozen_data = NULL; 920 } 921 922 spin_lock(&journal->j_list_lock); 923 cp_transaction = jh->b_cp_transaction; 924 if (cp_transaction) { 925 JBUFFER_TRACE(jh, "remove from old cp transaction"); 926 cp_transaction->t_chp_stats.cs_dropped++; 927 __jbd2_journal_remove_checkpoint(jh); 928 } 929 930 /* Only re-checkpoint the buffer_head if it is marked 931 * dirty. If the buffer was added to the BJ_Forget list 932 * by jbd2_journal_forget, it may no longer be dirty and 933 * there's no point in keeping a checkpoint record for 934 * it. */ 935 936 /* A buffer which has been freed while still being 937 * journaled by a previous transaction may end up still 938 * being dirty here, but we want to avoid writing back 939 * that buffer in the future now that the last use has 940 * been committed. That's not only a performance gain, 941 * it also stops aliasing problems if the buffer is left 942 * behind for writeback and gets reallocated for another 943 * use in a different page. */ 944 if (buffer_freed(bh)) { 945 clear_buffer_freed(bh); 946 clear_buffer_jbddirty(bh); 947 } 948 949 if (buffer_jbddirty(bh)) { 950 JBUFFER_TRACE(jh, "add to new checkpointing trans"); 951 __jbd2_journal_insert_checkpoint(jh, commit_transaction); 952 JBUFFER_TRACE(jh, "refile for checkpoint writeback"); 953 __jbd2_journal_refile_buffer(jh); 954 jbd_unlock_bh_state(bh); 955 } else { 956 J_ASSERT_BH(bh, !buffer_dirty(bh)); 957 /* The buffer on BJ_Forget list and not jbddirty means 958 * it has been freed by this transaction and hence it 959 * could not have been reallocated until this 960 * transaction has committed. *BUT* it could be 961 * reallocated once we have written all the data to 962 * disk and before we process the buffer on BJ_Forget 963 * list. */ 964 JBUFFER_TRACE(jh, "refile or unfile freed buffer"); 965 __jbd2_journal_refile_buffer(jh); 966 if (!jh->b_transaction) { 967 jbd_unlock_bh_state(bh); 968 /* needs a brelse */ 969 jbd2_journal_remove_journal_head(bh); 970 release_buffer_page(bh); 971 } else 972 jbd_unlock_bh_state(bh); 973 } 974 cond_resched_lock(&journal->j_list_lock); 975 } 976 spin_unlock(&journal->j_list_lock); 977 /* 978 * This is a bit sleazy. We use j_list_lock to protect transition 979 * of a transaction into T_FINISHED state and calling 980 * __jbd2_journal_drop_transaction(). Otherwise we could race with 981 * other checkpointing code processing the transaction... 982 */ 983 spin_lock(&journal->j_state_lock); 984 spin_lock(&journal->j_list_lock); 985 /* 986 * Now recheck if some buffers did not get attached to the transaction 987 * while the lock was dropped... 988 */ 989 if (commit_transaction->t_forget) { 990 spin_unlock(&journal->j_list_lock); 991 spin_unlock(&journal->j_state_lock); 992 goto restart_loop; 993 } 994 995 /* Done with this transaction! */ 996 997 jbd_debug(3, "JBD: commit phase 8\n"); 998 999 J_ASSERT(commit_transaction->t_state == T_COMMIT); 1000 1001 commit_transaction->t_start = jiffies; 1002 stats.u.run.rs_logging = jbd2_time_diff(stats.u.run.rs_logging, 1003 commit_transaction->t_start); 1004 1005 /* 1006 * File the transaction for history 1007 */ 1008 stats.ts_type = JBD2_STATS_RUN; 1009 stats.ts_tid = commit_transaction->t_tid; 1010 stats.u.run.rs_handle_count = commit_transaction->t_handle_count; 1011 spin_lock(&journal->j_history_lock); 1012 memcpy(journal->j_history + journal->j_history_cur, &stats, 1013 sizeof(stats)); 1014 if (++journal->j_history_cur == journal->j_history_max) 1015 journal->j_history_cur = 0; 1016 1017 /* 1018 * Calculate overall stats 1019 */ 1020 journal->j_stats.ts_tid++; 1021 journal->j_stats.u.run.rs_wait += stats.u.run.rs_wait; 1022 journal->j_stats.u.run.rs_running += stats.u.run.rs_running; 1023 journal->j_stats.u.run.rs_locked += stats.u.run.rs_locked; 1024 journal->j_stats.u.run.rs_flushing += stats.u.run.rs_flushing; 1025 journal->j_stats.u.run.rs_logging += stats.u.run.rs_logging; 1026 journal->j_stats.u.run.rs_handle_count += stats.u.run.rs_handle_count; 1027 journal->j_stats.u.run.rs_blocks += stats.u.run.rs_blocks; 1028 journal->j_stats.u.run.rs_blocks_logged += stats.u.run.rs_blocks_logged; 1029 spin_unlock(&journal->j_history_lock); 1030 1031 commit_transaction->t_state = T_FINISHED; 1032 J_ASSERT(commit_transaction == journal->j_committing_transaction); 1033 journal->j_commit_sequence = commit_transaction->t_tid; 1034 journal->j_committing_transaction = NULL; 1035 spin_unlock(&journal->j_state_lock); 1036 1037 if (commit_transaction->t_checkpoint_list == NULL && 1038 commit_transaction->t_checkpoint_io_list == NULL) { 1039 __jbd2_journal_drop_transaction(journal, commit_transaction); 1040 } else { 1041 if (journal->j_checkpoint_transactions == NULL) { 1042 journal->j_checkpoint_transactions = commit_transaction; 1043 commit_transaction->t_cpnext = commit_transaction; 1044 commit_transaction->t_cpprev = commit_transaction; 1045 } else { 1046 commit_transaction->t_cpnext = 1047 journal->j_checkpoint_transactions; 1048 commit_transaction->t_cpprev = 1049 commit_transaction->t_cpnext->t_cpprev; 1050 commit_transaction->t_cpnext->t_cpprev = 1051 commit_transaction; 1052 commit_transaction->t_cpprev->t_cpnext = 1053 commit_transaction; 1054 } 1055 } 1056 spin_unlock(&journal->j_list_lock); 1057 1058 jbd_debug(1, "JBD: commit %d complete, head %d\n", 1059 journal->j_commit_sequence, journal->j_tail_sequence); 1060 1061 wake_up(&journal->j_wait_done_commit); 1062 } 1063