1/* 2 * linux/fs/jbd/transaction.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 * Generic filesystem transaction handling code; part of the ext2fs 13 * journaling system. 14 * 15 * This file manages transactions (compound commits managed by the 16 * journaling code) and handles (individual atomic operations by the 17 * filesystem). 18 */ 19 20#include <linux/time.h> 21#include <linux/fs.h> 22#include <linux/jbd.h> 23#include <linux/errno.h> 24#include <linux/slab.h> 25#include <linux/timer.h> 26#include <linux/mm.h> 27#include <linux/highmem.h> 28#include <linux/hrtimer.h> 29 30static void __journal_temp_unlink_buffer(struct journal_head *jh); 31 32/* 33 * get_transaction: obtain a new transaction_t object. 34 * 35 * Simply allocate and initialise a new transaction. Create it in 36 * RUNNING state and add it to the current journal (which should not 37 * have an existing running transaction: we only make a new transaction 38 * once we have started to commit the old one). 39 * 40 * Preconditions: 41 * The journal MUST be locked. We don't perform atomic mallocs on the 42 * new transaction and we can't block without protecting against other 43 * processes trying to touch the journal while it is in transition. 44 * 45 * Called under j_state_lock 46 */ 47 48static transaction_t * 49get_transaction(journal_t *journal, transaction_t *transaction) 50{ 51 transaction->t_journal = journal; 52 transaction->t_state = T_RUNNING; 53 transaction->t_start_time = ktime_get(); 54 transaction->t_tid = journal->j_transaction_sequence++; 55 transaction->t_expires = jiffies + journal->j_commit_interval; 56 spin_lock_init(&transaction->t_handle_lock); 57 58 /* Set up the commit timer for the new transaction. */ 59 journal->j_commit_timer.expires = 60 round_jiffies_up(transaction->t_expires); 61 add_timer(&journal->j_commit_timer); 62 63 J_ASSERT(journal->j_running_transaction == NULL); 64 journal->j_running_transaction = transaction; 65 66 return transaction; 67} 68 69/* 70 * Handle management. 71 * 72 * A handle_t is an object which represents a single atomic update to a 73 * filesystem, and which tracks all of the modifications which form part 74 * of that one update. 75 */ 76 77/* 78 * start_this_handle: Given a handle, deal with any locking or stalling 79 * needed to make sure that there is enough journal space for the handle 80 * to begin. Attach the handle to a transaction and set up the 81 * transaction's buffer credits. 82 */ 83 84static int start_this_handle(journal_t *journal, handle_t *handle) 85{ 86 transaction_t *transaction; 87 int needed; 88 int nblocks = handle->h_buffer_credits; 89 transaction_t *new_transaction = NULL; 90 int ret = 0; 91 92 if (nblocks > journal->j_max_transaction_buffers) { 93 printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n", 94 current->comm, nblocks, 95 journal->j_max_transaction_buffers); 96 ret = -ENOSPC; 97 goto out; 98 } 99 100alloc_transaction: 101 if (!journal->j_running_transaction) { 102 new_transaction = kzalloc(sizeof(*new_transaction), 103 GFP_NOFS|__GFP_NOFAIL); 104 if (!new_transaction) { 105 ret = -ENOMEM; 106 goto out; 107 } 108 } 109 110 jbd_debug(3, "New handle %p going live.\n", handle); 111 112repeat: 113 114 /* 115 * We need to hold j_state_lock until t_updates has been incremented, 116 * for proper journal barrier handling 117 */ 118 spin_lock(&journal->j_state_lock); 119repeat_locked: 120 if (is_journal_aborted(journal) || 121 (journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) { 122 spin_unlock(&journal->j_state_lock); 123 ret = -EROFS; 124 goto out; 125 } 126 127 /* Wait on the journal's transaction barrier if necessary */ 128 if (journal->j_barrier_count) { 129 spin_unlock(&journal->j_state_lock); 130 wait_event(journal->j_wait_transaction_locked, 131 journal->j_barrier_count == 0); 132 goto repeat; 133 } 134 135 if (!journal->j_running_transaction) { 136 if (!new_transaction) { 137 spin_unlock(&journal->j_state_lock); 138 goto alloc_transaction; 139 } 140 get_transaction(journal, new_transaction); 141 new_transaction = NULL; 142 } 143 144 transaction = journal->j_running_transaction; 145 146 /* 147 * If the current transaction is locked down for commit, wait for the 148 * lock to be released. 149 */ 150 if (transaction->t_state == T_LOCKED) { 151 DEFINE_WAIT(wait); 152 153 prepare_to_wait(&journal->j_wait_transaction_locked, 154 &wait, TASK_UNINTERRUPTIBLE); 155 spin_unlock(&journal->j_state_lock); 156 schedule(); 157 finish_wait(&journal->j_wait_transaction_locked, &wait); 158 goto repeat; 159 } 160 161 /* 162 * If there is not enough space left in the log to write all potential 163 * buffers requested by this operation, we need to stall pending a log 164 * checkpoint to free some more log space. 165 */ 166 spin_lock(&transaction->t_handle_lock); 167 needed = transaction->t_outstanding_credits + nblocks; 168 169 if (needed > journal->j_max_transaction_buffers) { 170 /* 171 * If the current transaction is already too large, then start 172 * to commit it: we can then go back and attach this handle to 173 * a new transaction. 174 */ 175 DEFINE_WAIT(wait); 176 177 jbd_debug(2, "Handle %p starting new commit...\n", handle); 178 spin_unlock(&transaction->t_handle_lock); 179 prepare_to_wait(&journal->j_wait_transaction_locked, &wait, 180 TASK_UNINTERRUPTIBLE); 181 __log_start_commit(journal, transaction->t_tid); 182 spin_unlock(&journal->j_state_lock); 183 schedule(); 184 finish_wait(&journal->j_wait_transaction_locked, &wait); 185 goto repeat; 186 } 187 188 /* 189 * The commit code assumes that it can get enough log space 190 * without forcing a checkpoint. This is *critical* for 191 * correctness: a checkpoint of a buffer which is also 192 * associated with a committing transaction creates a deadlock, 193 * so commit simply cannot force through checkpoints. 194 * 195 * We must therefore ensure the necessary space in the journal 196 * *before* starting to dirty potentially checkpointed buffers 197 * in the new transaction. 198 * 199 * The worst part is, any transaction currently committing can 200 * reduce the free space arbitrarily. Be careful to account for 201 * those buffers when checkpointing. 202 */ 203 204 /* 205 * @@@ AKPM: This seems rather over-defensive. We're giving commit 206 * a _lot_ of headroom: 1/4 of the journal plus the size of 207 * the committing transaction. Really, we only need to give it 208 * committing_transaction->t_outstanding_credits plus "enough" for 209 * the log control blocks. 210 * Also, this test is inconsistent with the matching one in 211 * journal_extend(). 212 */ 213 if (__log_space_left(journal) < jbd_space_needed(journal)) { 214 jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle); 215 spin_unlock(&transaction->t_handle_lock); 216 __log_wait_for_space(journal); 217 goto repeat_locked; 218 } 219 220 /* OK, account for the buffers that this operation expects to 221 * use and add the handle to the running transaction. */ 222 223 handle->h_transaction = transaction; 224 transaction->t_outstanding_credits += nblocks; 225 transaction->t_updates++; 226 transaction->t_handle_count++; 227 jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n", 228 handle, nblocks, transaction->t_outstanding_credits, 229 __log_space_left(journal)); 230 spin_unlock(&transaction->t_handle_lock); 231 spin_unlock(&journal->j_state_lock); 232 233 lock_map_acquire(&handle->h_lockdep_map); 234out: 235 if (unlikely(new_transaction)) /* It's usually NULL */ 236 kfree(new_transaction); 237 return ret; 238} 239 240static struct lock_class_key jbd_handle_key; 241 242/* Allocate a new handle. This should probably be in a slab... */ 243static handle_t *new_handle(int nblocks) 244{ 245 handle_t *handle = jbd_alloc_handle(GFP_NOFS); 246 if (!handle) 247 return NULL; 248 handle->h_buffer_credits = nblocks; 249 handle->h_ref = 1; 250 251 lockdep_init_map(&handle->h_lockdep_map, "jbd_handle", &jbd_handle_key, 0); 252 253 return handle; 254} 255 256/** 257 * handle_t *journal_start() - Obtain a new handle. 258 * @journal: Journal to start transaction on. 259 * @nblocks: number of block buffer we might modify 260 * 261 * We make sure that the transaction can guarantee at least nblocks of 262 * modified buffers in the log. We block until the log can guarantee 263 * that much space. 264 * 265 * This function is visible to journal users (like ext3fs), so is not 266 * called with the journal already locked. 267 * 268 * Return a pointer to a newly allocated handle, or an ERR_PTR() value 269 * on failure. 270 */ 271handle_t *journal_start(journal_t *journal, int nblocks) 272{ 273 handle_t *handle = journal_current_handle(); 274 int err; 275 276 if (!journal) 277 return ERR_PTR(-EROFS); 278 279 if (handle) { 280 J_ASSERT(handle->h_transaction->t_journal == journal); 281 handle->h_ref++; 282 return handle; 283 } 284 285 handle = new_handle(nblocks); 286 if (!handle) 287 return ERR_PTR(-ENOMEM); 288 289 current->journal_info = handle; 290 291 err = start_this_handle(journal, handle); 292 if (err < 0) { 293 jbd_free_handle(handle); 294 current->journal_info = NULL; 295 handle = ERR_PTR(err); 296 } 297 return handle; 298} 299 300/** 301 * int journal_extend() - extend buffer credits. 302 * @handle: handle to 'extend' 303 * @nblocks: nr blocks to try to extend by. 304 * 305 * Some transactions, such as large extends and truncates, can be done 306 * atomically all at once or in several stages. The operation requests 307 * a credit for a number of buffer modications in advance, but can 308 * extend its credit if it needs more. 309 * 310 * journal_extend tries to give the running handle more buffer credits. 311 * It does not guarantee that allocation - this is a best-effort only. 312 * The calling process MUST be able to deal cleanly with a failure to 313 * extend here. 314 * 315 * Return 0 on success, non-zero on failure. 316 * 317 * return code < 0 implies an error 318 * return code > 0 implies normal transaction-full status. 319 */ 320int journal_extend(handle_t *handle, int nblocks) 321{ 322 transaction_t *transaction = handle->h_transaction; 323 journal_t *journal = transaction->t_journal; 324 int result; 325 int wanted; 326 327 result = -EIO; 328 if (is_handle_aborted(handle)) 329 goto out; 330 331 result = 1; 332 333 spin_lock(&journal->j_state_lock); 334 335 /* Don't extend a locked-down transaction! */ 336 if (handle->h_transaction->t_state != T_RUNNING) { 337 jbd_debug(3, "denied handle %p %d blocks: " 338 "transaction not running\n", handle, nblocks); 339 goto error_out; 340 } 341 342 spin_lock(&transaction->t_handle_lock); 343 wanted = transaction->t_outstanding_credits + nblocks; 344 345 if (wanted > journal->j_max_transaction_buffers) { 346 jbd_debug(3, "denied handle %p %d blocks: " 347 "transaction too large\n", handle, nblocks); 348 goto unlock; 349 } 350 351 if (wanted > __log_space_left(journal)) { 352 jbd_debug(3, "denied handle %p %d blocks: " 353 "insufficient log space\n", handle, nblocks); 354 goto unlock; 355 } 356 357 handle->h_buffer_credits += nblocks; 358 transaction->t_outstanding_credits += nblocks; 359 result = 0; 360 361 jbd_debug(3, "extended handle %p by %d\n", handle, nblocks); 362unlock: 363 spin_unlock(&transaction->t_handle_lock); 364error_out: 365 spin_unlock(&journal->j_state_lock); 366out: 367 return result; 368} 369 370 371/** 372 * int journal_restart() - restart a handle. 373 * @handle: handle to restart 374 * @nblocks: nr credits requested 375 * 376 * Restart a handle for a multi-transaction filesystem 377 * operation. 378 * 379 * If the journal_extend() call above fails to grant new buffer credits 380 * to a running handle, a call to journal_restart will commit the 381 * handle's transaction so far and reattach the handle to a new 382 * transaction capabable of guaranteeing the requested number of 383 * credits. 384 */ 385 386int journal_restart(handle_t *handle, int nblocks) 387{ 388 transaction_t *transaction = handle->h_transaction; 389 journal_t *journal = transaction->t_journal; 390 int ret; 391 392 /* If we've had an abort of any type, don't even think about 393 * actually doing the restart! */ 394 if (is_handle_aborted(handle)) 395 return 0; 396 397 /* 398 * First unlink the handle from its current transaction, and start the 399 * commit on that. 400 */ 401 J_ASSERT(transaction->t_updates > 0); 402 J_ASSERT(journal_current_handle() == handle); 403 404 spin_lock(&journal->j_state_lock); 405 spin_lock(&transaction->t_handle_lock); 406 transaction->t_outstanding_credits -= handle->h_buffer_credits; 407 transaction->t_updates--; 408 409 if (!transaction->t_updates) 410 wake_up(&journal->j_wait_updates); 411 spin_unlock(&transaction->t_handle_lock); 412 413 jbd_debug(2, "restarting handle %p\n", handle); 414 __log_start_commit(journal, transaction->t_tid); 415 spin_unlock(&journal->j_state_lock); 416 417 lock_map_release(&handle->h_lockdep_map); 418 handle->h_buffer_credits = nblocks; 419 ret = start_this_handle(journal, handle); 420 return ret; 421} 422 423 424/** 425 * void journal_lock_updates () - establish a transaction barrier. 426 * @journal: Journal to establish a barrier on. 427 * 428 * This locks out any further updates from being started, and blocks until all 429 * existing updates have completed, returning only once the journal is in a 430 * quiescent state with no updates running. 431 * 432 * We do not use simple mutex for synchronization as there are syscalls which 433 * want to return with filesystem locked and that trips up lockdep. Also 434 * hibernate needs to lock filesystem but locked mutex then blocks hibernation. 435 * Since locking filesystem is rare operation, we use simple counter and 436 * waitqueue for locking. 437 */ 438void journal_lock_updates(journal_t *journal) 439{ 440 DEFINE_WAIT(wait); 441 442wait: 443 /* Wait for previous locked operation to finish */ 444 wait_event(journal->j_wait_transaction_locked, 445 journal->j_barrier_count == 0); 446 447 spin_lock(&journal->j_state_lock); 448 /* 449 * Check reliably under the lock whether we are the ones winning the race 450 * and locking the journal 451 */ 452 if (journal->j_barrier_count > 0) { 453 spin_unlock(&journal->j_state_lock); 454 goto wait; 455 } 456 ++journal->j_barrier_count; 457 458 /* Wait until there are no running updates */ 459 while (1) { 460 transaction_t *transaction = journal->j_running_transaction; 461 462 if (!transaction) 463 break; 464 465 spin_lock(&transaction->t_handle_lock); 466 if (!transaction->t_updates) { 467 spin_unlock(&transaction->t_handle_lock); 468 break; 469 } 470 prepare_to_wait(&journal->j_wait_updates, &wait, 471 TASK_UNINTERRUPTIBLE); 472 spin_unlock(&transaction->t_handle_lock); 473 spin_unlock(&journal->j_state_lock); 474 schedule(); 475 finish_wait(&journal->j_wait_updates, &wait); 476 spin_lock(&journal->j_state_lock); 477 } 478 spin_unlock(&journal->j_state_lock); 479} 480 481/** 482 * void journal_unlock_updates (journal_t* journal) - release barrier 483 * @journal: Journal to release the barrier on. 484 * 485 * Release a transaction barrier obtained with journal_lock_updates(). 486 */ 487void journal_unlock_updates (journal_t *journal) 488{ 489 J_ASSERT(journal->j_barrier_count != 0); 490 491 spin_lock(&journal->j_state_lock); 492 --journal->j_barrier_count; 493 spin_unlock(&journal->j_state_lock); 494 wake_up(&journal->j_wait_transaction_locked); 495} 496 497static void warn_dirty_buffer(struct buffer_head *bh) 498{ 499 char b[BDEVNAME_SIZE]; 500 501 printk(KERN_WARNING 502 "JBD: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). " 503 "There's a risk of filesystem corruption in case of system " 504 "crash.\n", 505 bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr); 506} 507 508/* 509 * If the buffer is already part of the current transaction, then there 510 * is nothing we need to do. If it is already part of a prior 511 * transaction which we are still committing to disk, then we need to 512 * make sure that we do not overwrite the old copy: we do copy-out to 513 * preserve the copy going to disk. We also account the buffer against 514 * the handle's metadata buffer credits (unless the buffer is already 515 * part of the transaction, that is). 516 * 517 */ 518static int 519do_get_write_access(handle_t *handle, struct journal_head *jh, 520 int force_copy) 521{ 522 struct buffer_head *bh; 523 transaction_t *transaction; 524 journal_t *journal; 525 int error; 526 char *frozen_buffer = NULL; 527 int need_copy = 0; 528 529 if (is_handle_aborted(handle)) 530 return -EROFS; 531 532 transaction = handle->h_transaction; 533 journal = transaction->t_journal; 534 535 jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy); 536 537 JBUFFER_TRACE(jh, "entry"); 538repeat: 539 bh = jh2bh(jh); 540 541 /* @@@ Need to check for errors here at some point. */ 542 543 lock_buffer(bh); 544 jbd_lock_bh_state(bh); 545 546 /* We now hold the buffer lock so it is safe to query the buffer 547 * state. Is the buffer dirty? 548 * 549 * If so, there are two possibilities. The buffer may be 550 * non-journaled, and undergoing a quite legitimate writeback. 551 * Otherwise, it is journaled, and we don't expect dirty buffers 552 * in that state (the buffers should be marked JBD_Dirty 553 * instead.) So either the IO is being done under our own 554 * control and this is a bug, or it's a third party IO such as 555 * dump(8) (which may leave the buffer scheduled for read --- 556 * ie. locked but not dirty) or tune2fs (which may actually have 557 * the buffer dirtied, ugh.) */ 558 559 if (buffer_dirty(bh)) { 560 /* 561 * First question: is this buffer already part of the current 562 * transaction or the existing committing transaction? 563 */ 564 if (jh->b_transaction) { 565 J_ASSERT_JH(jh, 566 jh->b_transaction == transaction || 567 jh->b_transaction == 568 journal->j_committing_transaction); 569 if (jh->b_next_transaction) 570 J_ASSERT_JH(jh, jh->b_next_transaction == 571 transaction); 572 warn_dirty_buffer(bh); 573 } 574 /* 575 * In any case we need to clean the dirty flag and we must 576 * do it under the buffer lock to be sure we don't race 577 * with running write-out. 578 */ 579 JBUFFER_TRACE(jh, "Journalling dirty buffer"); 580 clear_buffer_dirty(bh); 581 set_buffer_jbddirty(bh); 582 } 583 584 unlock_buffer(bh); 585 586 error = -EROFS; 587 if (is_handle_aborted(handle)) { 588 jbd_unlock_bh_state(bh); 589 goto out; 590 } 591 error = 0; 592 593 /* 594 * The buffer is already part of this transaction if b_transaction or 595 * b_next_transaction points to it 596 */ 597 if (jh->b_transaction == transaction || 598 jh->b_next_transaction == transaction) 599 goto done; 600 601 /* 602 * this is the first time this transaction is touching this buffer, 603 * reset the modified flag 604 */ 605 jh->b_modified = 0; 606 607 /* 608 * If there is already a copy-out version of this buffer, then we don't 609 * need to make another one 610 */ 611 if (jh->b_frozen_data) { 612 JBUFFER_TRACE(jh, "has frozen data"); 613 J_ASSERT_JH(jh, jh->b_next_transaction == NULL); 614 jh->b_next_transaction = transaction; 615 goto done; 616 } 617 618 /* Is there data here we need to preserve? */ 619 620 if (jh->b_transaction && jh->b_transaction != transaction) { 621 JBUFFER_TRACE(jh, "owned by older transaction"); 622 J_ASSERT_JH(jh, jh->b_next_transaction == NULL); 623 J_ASSERT_JH(jh, jh->b_transaction == 624 journal->j_committing_transaction); 625 626 /* There is one case we have to be very careful about. 627 * If the committing transaction is currently writing 628 * this buffer out to disk and has NOT made a copy-out, 629 * then we cannot modify the buffer contents at all 630 * right now. The essence of copy-out is that it is the 631 * extra copy, not the primary copy, which gets 632 * journaled. If the primary copy is already going to 633 * disk then we cannot do copy-out here. */ 634 635 if (jh->b_jlist == BJ_Shadow) { 636 DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow); 637 wait_queue_head_t *wqh; 638 639 wqh = bit_waitqueue(&bh->b_state, BH_Unshadow); 640 641 JBUFFER_TRACE(jh, "on shadow: sleep"); 642 jbd_unlock_bh_state(bh); 643 /* commit wakes up all shadow buffers after IO */ 644 for ( ; ; ) { 645 prepare_to_wait(wqh, &wait.wait, 646 TASK_UNINTERRUPTIBLE); 647 if (jh->b_jlist != BJ_Shadow) 648 break; 649 schedule(); 650 } 651 finish_wait(wqh, &wait.wait); 652 goto repeat; 653 } 654 655 /* Only do the copy if the currently-owning transaction 656 * still needs it. If it is on the Forget list, the 657 * committing transaction is past that stage. The 658 * buffer had better remain locked during the kmalloc, 659 * but that should be true --- we hold the journal lock 660 * still and the buffer is already on the BUF_JOURNAL 661 * list so won't be flushed. 662 * 663 * Subtle point, though: if this is a get_undo_access, 664 * then we will be relying on the frozen_data to contain 665 * the new value of the committed_data record after the 666 * transaction, so we HAVE to force the frozen_data copy 667 * in that case. */ 668 669 if (jh->b_jlist != BJ_Forget || force_copy) { 670 JBUFFER_TRACE(jh, "generate frozen data"); 671 if (!frozen_buffer) { 672 JBUFFER_TRACE(jh, "allocate memory for buffer"); 673 jbd_unlock_bh_state(bh); 674 frozen_buffer = 675 jbd_alloc(jh2bh(jh)->b_size, 676 GFP_NOFS); 677 if (!frozen_buffer) { 678 printk(KERN_ERR 679 "%s: OOM for frozen_buffer\n", 680 __func__); 681 JBUFFER_TRACE(jh, "oom!"); 682 error = -ENOMEM; 683 jbd_lock_bh_state(bh); 684 goto done; 685 } 686 goto repeat; 687 } 688 jh->b_frozen_data = frozen_buffer; 689 frozen_buffer = NULL; 690 need_copy = 1; 691 } 692 jh->b_next_transaction = transaction; 693 } 694 695 696 /* 697 * Finally, if the buffer is not journaled right now, we need to make 698 * sure it doesn't get written to disk before the caller actually 699 * commits the new data 700 */ 701 if (!jh->b_transaction) { 702 JBUFFER_TRACE(jh, "no transaction"); 703 J_ASSERT_JH(jh, !jh->b_next_transaction); 704 JBUFFER_TRACE(jh, "file as BJ_Reserved"); 705 spin_lock(&journal->j_list_lock); 706 __journal_file_buffer(jh, transaction, BJ_Reserved); 707 spin_unlock(&journal->j_list_lock); 708 } 709 710done: 711 if (need_copy) { 712 struct page *page; 713 int offset; 714 char *source; 715 716 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)), 717 "Possible IO failure.\n"); 718 page = jh2bh(jh)->b_page; 719 offset = offset_in_page(jh2bh(jh)->b_data); 720 source = kmap_atomic(page); 721 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size); 722 kunmap_atomic(source); 723 } 724 jbd_unlock_bh_state(bh); 725 726 /* 727 * If we are about to journal a buffer, then any revoke pending on it is 728 * no longer valid 729 */ 730 journal_cancel_revoke(handle, jh); 731 732out: 733 if (unlikely(frozen_buffer)) /* It's usually NULL */ 734 jbd_free(frozen_buffer, bh->b_size); 735 736 JBUFFER_TRACE(jh, "exit"); 737 return error; 738} 739 740/** 741 * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update. 742 * @handle: transaction to add buffer modifications to 743 * @bh: bh to be used for metadata writes 744 * 745 * Returns an error code or 0 on success. 746 * 747 * In full data journalling mode the buffer may be of type BJ_AsyncData, 748 * because we're write()ing a buffer which is also part of a shared mapping. 749 */ 750 751int journal_get_write_access(handle_t *handle, struct buffer_head *bh) 752{ 753 struct journal_head *jh = journal_add_journal_head(bh); 754 int rc; 755 756 /* We do not want to get caught playing with fields which the 757 * log thread also manipulates. Make sure that the buffer 758 * completes any outstanding IO before proceeding. */ 759 rc = do_get_write_access(handle, jh, 0); 760 journal_put_journal_head(jh); 761 return rc; 762} 763 764 765/* 766 * When the user wants to journal a newly created buffer_head 767 * (ie. getblk() returned a new buffer and we are going to populate it 768 * manually rather than reading off disk), then we need to keep the 769 * buffer_head locked until it has been completely filled with new 770 * data. In this case, we should be able to make the assertion that 771 * the bh is not already part of an existing transaction. 772 * 773 * The buffer should already be locked by the caller by this point. 774 * There is no lock ranking violation: it was a newly created, 775 * unlocked buffer beforehand. */ 776 777/** 778 * int journal_get_create_access () - notify intent to use newly created bh 779 * @handle: transaction to new buffer to 780 * @bh: new buffer. 781 * 782 * Call this if you create a new bh. 783 */ 784int journal_get_create_access(handle_t *handle, struct buffer_head *bh) 785{ 786 transaction_t *transaction = handle->h_transaction; 787 journal_t *journal = transaction->t_journal; 788 struct journal_head *jh = journal_add_journal_head(bh); 789 int err; 790 791 jbd_debug(5, "journal_head %p\n", jh); 792 err = -EROFS; 793 if (is_handle_aborted(handle)) 794 goto out; 795 err = 0; 796 797 JBUFFER_TRACE(jh, "entry"); 798 /* 799 * The buffer may already belong to this transaction due to pre-zeroing 800 * in the filesystem's new_block code. It may also be on the previous, 801 * committing transaction's lists, but it HAS to be in Forget state in 802 * that case: the transaction must have deleted the buffer for it to be 803 * reused here. 804 */ 805 jbd_lock_bh_state(bh); 806 spin_lock(&journal->j_list_lock); 807 J_ASSERT_JH(jh, (jh->b_transaction == transaction || 808 jh->b_transaction == NULL || 809 (jh->b_transaction == journal->j_committing_transaction && 810 jh->b_jlist == BJ_Forget))); 811 812 J_ASSERT_JH(jh, jh->b_next_transaction == NULL); 813 J_ASSERT_JH(jh, buffer_locked(jh2bh(jh))); 814 815 if (jh->b_transaction == NULL) { 816 /* 817 * Previous journal_forget() could have left the buffer 818 * with jbddirty bit set because it was being committed. When 819 * the commit finished, we've filed the buffer for 820 * checkpointing and marked it dirty. Now we are reallocating 821 * the buffer so the transaction freeing it must have 822 * committed and so it's safe to clear the dirty bit. 823 */ 824 clear_buffer_dirty(jh2bh(jh)); 825 826 /* first access by this transaction */ 827 jh->b_modified = 0; 828 829 JBUFFER_TRACE(jh, "file as BJ_Reserved"); 830 __journal_file_buffer(jh, transaction, BJ_Reserved); 831 } else if (jh->b_transaction == journal->j_committing_transaction) { 832 /* first access by this transaction */ 833 jh->b_modified = 0; 834 835 JBUFFER_TRACE(jh, "set next transaction"); 836 jh->b_next_transaction = transaction; 837 } 838 spin_unlock(&journal->j_list_lock); 839 jbd_unlock_bh_state(bh); 840 841 /* 842 * akpm: I added this. ext3_alloc_branch can pick up new indirect 843 * blocks which contain freed but then revoked metadata. We need 844 * to cancel the revoke in case we end up freeing it yet again 845 * and the reallocating as data - this would cause a second revoke, 846 * which hits an assertion error. 847 */ 848 JBUFFER_TRACE(jh, "cancelling revoke"); 849 journal_cancel_revoke(handle, jh); 850out: 851 journal_put_journal_head(jh); 852 return err; 853} 854 855/** 856 * int journal_get_undo_access() - Notify intent to modify metadata with non-rewindable consequences 857 * @handle: transaction 858 * @bh: buffer to undo 859 * 860 * Sometimes there is a need to distinguish between metadata which has 861 * been committed to disk and that which has not. The ext3fs code uses 862 * this for freeing and allocating space, we have to make sure that we 863 * do not reuse freed space until the deallocation has been committed, 864 * since if we overwrote that space we would make the delete 865 * un-rewindable in case of a crash. 866 * 867 * To deal with that, journal_get_undo_access requests write access to a 868 * buffer for parts of non-rewindable operations such as delete 869 * operations on the bitmaps. The journaling code must keep a copy of 870 * the buffer's contents prior to the undo_access call until such time 871 * as we know that the buffer has definitely been committed to disk. 872 * 873 * We never need to know which transaction the committed data is part 874 * of, buffers touched here are guaranteed to be dirtied later and so 875 * will be committed to a new transaction in due course, at which point 876 * we can discard the old committed data pointer. 877 * 878 * Returns error number or 0 on success. 879 */ 880int journal_get_undo_access(handle_t *handle, struct buffer_head *bh) 881{ 882 int err; 883 struct journal_head *jh = journal_add_journal_head(bh); 884 char *committed_data = NULL; 885 886 JBUFFER_TRACE(jh, "entry"); 887 888 /* 889 * Do this first --- it can drop the journal lock, so we want to 890 * make sure that obtaining the committed_data is done 891 * atomically wrt. completion of any outstanding commits. 892 */ 893 err = do_get_write_access(handle, jh, 1); 894 if (err) 895 goto out; 896 897repeat: 898 if (!jh->b_committed_data) { 899 committed_data = jbd_alloc(jh2bh(jh)->b_size, GFP_NOFS); 900 if (!committed_data) { 901 printk(KERN_ERR "%s: No memory for committed data\n", 902 __func__); 903 err = -ENOMEM; 904 goto out; 905 } 906 } 907 908 jbd_lock_bh_state(bh); 909 if (!jh->b_committed_data) { 910 /* Copy out the current buffer contents into the 911 * preserved, committed copy. */ 912 JBUFFER_TRACE(jh, "generate b_committed data"); 913 if (!committed_data) { 914 jbd_unlock_bh_state(bh); 915 goto repeat; 916 } 917 918 jh->b_committed_data = committed_data; 919 committed_data = NULL; 920 memcpy(jh->b_committed_data, bh->b_data, bh->b_size); 921 } 922 jbd_unlock_bh_state(bh); 923out: 924 journal_put_journal_head(jh); 925 if (unlikely(committed_data)) 926 jbd_free(committed_data, bh->b_size); 927 return err; 928} 929 930/** 931 * int journal_dirty_data() - mark a buffer as containing dirty data to be flushed 932 * @handle: transaction 933 * @bh: bufferhead to mark 934 * 935 * Description: 936 * Mark a buffer as containing dirty data which needs to be flushed before 937 * we can commit the current transaction. 938 * 939 * The buffer is placed on the transaction's data list and is marked as 940 * belonging to the transaction. 941 * 942 * Returns error number or 0 on success. 943 * 944 * journal_dirty_data() can be called via page_launder->ext3_writepage 945 * by kswapd. 946 */ 947int journal_dirty_data(handle_t *handle, struct buffer_head *bh) 948{ 949 journal_t *journal = handle->h_transaction->t_journal; 950 int need_brelse = 0; 951 struct journal_head *jh; 952 int ret = 0; 953 954 if (is_handle_aborted(handle)) 955 return ret; 956 957 jh = journal_add_journal_head(bh); 958 JBUFFER_TRACE(jh, "entry"); 959 960 /* 961 * The buffer could *already* be dirty. Writeout can start 962 * at any time. 963 */ 964 jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid); 965 966 /* 967 * What if the buffer is already part of a running transaction? 968 * 969 * There are two cases: 970 * 1) It is part of the current running transaction. Refile it, 971 * just in case we have allocated it as metadata, deallocated 972 * it, then reallocated it as data. 973 * 2) It is part of the previous, still-committing transaction. 974 * If all we want to do is to guarantee that the buffer will be 975 * written to disk before this new transaction commits, then 976 * being sure that the *previous* transaction has this same 977 * property is sufficient for us! Just leave it on its old 978 * transaction. 979 * 980 * In case (2), the buffer must not already exist as metadata 981 * --- that would violate write ordering (a transaction is free 982 * to write its data at any point, even before the previous 983 * committing transaction has committed). The caller must 984 * never, ever allow this to happen: there's nothing we can do 985 * about it in this layer. 986 */ 987 jbd_lock_bh_state(bh); 988 spin_lock(&journal->j_list_lock); 989 990 /* Now that we have bh_state locked, are we really still mapped? */ 991 if (!buffer_mapped(bh)) { 992 JBUFFER_TRACE(jh, "unmapped buffer, bailing out"); 993 goto no_journal; 994 } 995 996 if (jh->b_transaction) { 997 JBUFFER_TRACE(jh, "has transaction"); 998 if (jh->b_transaction != handle->h_transaction) { 999 JBUFFER_TRACE(jh, "belongs to older transaction"); 1000 J_ASSERT_JH(jh, jh->b_transaction == 1001 journal->j_committing_transaction); 1002 1003 /* @@@ IS THIS TRUE ? */ 1004 /* 1005 * Not any more. Scenario: someone does a write() 1006 * in data=journal mode. The buffer's transaction has 1007 * moved into commit. Then someone does another 1008 * write() to the file. We do the frozen data copyout 1009 * and set b_next_transaction to point to j_running_t. 1010 * And while we're in that state, someone does a 1011 * writepage() in an attempt to pageout the same area 1012 * of the file via a shared mapping. At present that 1013 * calls journal_dirty_data(), and we get right here. 1014 * It may be too late to journal the data. Simply 1015 * falling through to the next test will suffice: the 1016 * data will be dirty and wil be checkpointed. The 1017 * ordering comments in the next comment block still 1018 * apply. 1019 */ 1020 //J_ASSERT_JH(jh, jh->b_next_transaction == NULL); 1021 1022 /* 1023 * If we're journalling data, and this buffer was 1024 * subject to a write(), it could be metadata, forget 1025 * or shadow against the committing transaction. Now, 1026 * someone has dirtied the same darn page via a mapping 1027 * and it is being writepage()'d. 1028 * We *could* just steal the page from commit, with some 1029 * fancy locking there. Instead, we just skip it - 1030 * don't tie the page's buffers to the new transaction 1031 * at all. 1032 * Implication: if we crash before the writepage() data 1033 * is written into the filesystem, recovery will replay 1034 * the write() data. 1035 */ 1036 if (jh->b_jlist != BJ_None && 1037 jh->b_jlist != BJ_SyncData && 1038 jh->b_jlist != BJ_Locked) { 1039 JBUFFER_TRACE(jh, "Not stealing"); 1040 goto no_journal; 1041 } 1042 1043 /* 1044 * This buffer may be undergoing writeout in commit. We 1045 * can't return from here and let the caller dirty it 1046 * again because that can cause the write-out loop in 1047 * commit to never terminate. 1048 */ 1049 if (buffer_dirty(bh)) { 1050 get_bh(bh); 1051 spin_unlock(&journal->j_list_lock); 1052 jbd_unlock_bh_state(bh); 1053 need_brelse = 1; 1054 sync_dirty_buffer(bh); 1055 jbd_lock_bh_state(bh); 1056 spin_lock(&journal->j_list_lock); 1057 /* Since we dropped the lock... */ 1058 if (!buffer_mapped(bh)) { 1059 JBUFFER_TRACE(jh, "buffer got unmapped"); 1060 goto no_journal; 1061 } 1062 /* The buffer may become locked again at any 1063 time if it is redirtied */ 1064 } 1065 1066 /* 1067 * We cannot remove the buffer with io error from the 1068 * committing transaction, because otherwise it would 1069 * miss the error and the commit would not abort. 1070 */ 1071 if (unlikely(!buffer_uptodate(bh))) { 1072 ret = -EIO; 1073 goto no_journal; 1074 } 1075 /* We might have slept so buffer could be refiled now */ 1076 if (jh->b_transaction != NULL && 1077 jh->b_transaction != handle->h_transaction) { 1078 JBUFFER_TRACE(jh, "unfile from commit"); 1079 __journal_temp_unlink_buffer(jh); 1080 /* It still points to the committing 1081 * transaction; move it to this one so 1082 * that the refile assert checks are 1083 * happy. */ 1084 jh->b_transaction = handle->h_transaction; 1085 } 1086 /* The buffer will be refiled below */ 1087 1088 } 1089 /* 1090 * Special case --- the buffer might actually have been 1091 * allocated and then immediately deallocated in the previous, 1092 * committing transaction, so might still be left on that 1093 * transaction's metadata lists. 1094 */ 1095 if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) { 1096 JBUFFER_TRACE(jh, "not on correct data list: unfile"); 1097 J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow); 1098 JBUFFER_TRACE(jh, "file as data"); 1099 __journal_file_buffer(jh, handle->h_transaction, 1100 BJ_SyncData); 1101 } 1102 } else { 1103 JBUFFER_TRACE(jh, "not on a transaction"); 1104 __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData); 1105 } 1106no_journal: 1107 spin_unlock(&journal->j_list_lock); 1108 jbd_unlock_bh_state(bh); 1109 if (need_brelse) { 1110 BUFFER_TRACE(bh, "brelse"); 1111 __brelse(bh); 1112 } 1113 JBUFFER_TRACE(jh, "exit"); 1114 journal_put_journal_head(jh); 1115 return ret; 1116} 1117 1118/** 1119 * int journal_dirty_metadata() - mark a buffer as containing dirty metadata 1120 * @handle: transaction to add buffer to. 1121 * @bh: buffer to mark 1122 * 1123 * Mark dirty metadata which needs to be journaled as part of the current 1124 * transaction. 1125 * 1126 * The buffer is placed on the transaction's metadata list and is marked 1127 * as belonging to the transaction. 1128 * 1129 * Returns error number or 0 on success. 1130 * 1131 * Special care needs to be taken if the buffer already belongs to the 1132 * current committing transaction (in which case we should have frozen 1133 * data present for that commit). In that case, we don't relink the 1134 * buffer: that only gets done when the old transaction finally 1135 * completes its commit. 1136 */ 1137int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh) 1138{ 1139 transaction_t *transaction = handle->h_transaction; 1140 journal_t *journal = transaction->t_journal; 1141 struct journal_head *jh = bh2jh(bh); 1142 1143 jbd_debug(5, "journal_head %p\n", jh); 1144 JBUFFER_TRACE(jh, "entry"); 1145 if (is_handle_aborted(handle)) 1146 goto out; 1147 1148 jbd_lock_bh_state(bh); 1149 1150 if (jh->b_modified == 0) { 1151 /* 1152 * This buffer's got modified and becoming part 1153 * of the transaction. This needs to be done 1154 * once a transaction -bzzz 1155 */ 1156 jh->b_modified = 1; 1157 J_ASSERT_JH(jh, handle->h_buffer_credits > 0); 1158 handle->h_buffer_credits--; 1159 } 1160 1161 /* 1162 * fastpath, to avoid expensive locking. If this buffer is already 1163 * on the running transaction's metadata list there is nothing to do. 1164 * Nobody can take it off again because there is a handle open. 1165 * I _think_ we're OK here with SMP barriers - a mistaken decision will 1166 * result in this test being false, so we go in and take the locks. 1167 */ 1168 if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) { 1169 JBUFFER_TRACE(jh, "fastpath"); 1170 J_ASSERT_JH(jh, jh->b_transaction == 1171 journal->j_running_transaction); 1172 goto out_unlock_bh; 1173 } 1174 1175 set_buffer_jbddirty(bh); 1176 1177 /* 1178 * Metadata already on the current transaction list doesn't 1179 * need to be filed. Metadata on another transaction's list must 1180 * be committing, and will be refiled once the commit completes: 1181 * leave it alone for now. 1182 */ 1183 if (jh->b_transaction != transaction) { 1184 JBUFFER_TRACE(jh, "already on other transaction"); 1185 J_ASSERT_JH(jh, jh->b_transaction == 1186 journal->j_committing_transaction); 1187 J_ASSERT_JH(jh, jh->b_next_transaction == transaction); 1188 /* And this case is illegal: we can't reuse another 1189 * transaction's data buffer, ever. */ 1190 goto out_unlock_bh; 1191 } 1192 1193 /* That test should have eliminated the following case: */ 1194 J_ASSERT_JH(jh, jh->b_frozen_data == NULL); 1195 1196 JBUFFER_TRACE(jh, "file as BJ_Metadata"); 1197 spin_lock(&journal->j_list_lock); 1198 __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata); 1199 spin_unlock(&journal->j_list_lock); 1200out_unlock_bh: 1201 jbd_unlock_bh_state(bh); 1202out: 1203 JBUFFER_TRACE(jh, "exit"); 1204 return 0; 1205} 1206 1207/* 1208 * journal_release_buffer: undo a get_write_access without any buffer 1209 * updates, if the update decided in the end that it didn't need access. 1210 * 1211 */ 1212void 1213journal_release_buffer(handle_t *handle, struct buffer_head *bh) 1214{ 1215 BUFFER_TRACE(bh, "entry"); 1216} 1217 1218/** 1219 * void journal_forget() - bforget() for potentially-journaled buffers. 1220 * @handle: transaction handle 1221 * @bh: bh to 'forget' 1222 * 1223 * We can only do the bforget if there are no commits pending against the 1224 * buffer. If the buffer is dirty in the current running transaction we 1225 * can safely unlink it. 1226 * 1227 * bh may not be a journalled buffer at all - it may be a non-JBD 1228 * buffer which came off the hashtable. Check for this. 1229 * 1230 * Decrements bh->b_count by one. 1231 * 1232 * Allow this call even if the handle has aborted --- it may be part of 1233 * the caller's cleanup after an abort. 1234 */ 1235int journal_forget (handle_t *handle, struct buffer_head *bh) 1236{ 1237 transaction_t *transaction = handle->h_transaction; 1238 journal_t *journal = transaction->t_journal; 1239 struct journal_head *jh; 1240 int drop_reserve = 0; 1241 int err = 0; 1242 int was_modified = 0; 1243 1244 BUFFER_TRACE(bh, "entry"); 1245 1246 jbd_lock_bh_state(bh); 1247 spin_lock(&journal->j_list_lock); 1248 1249 if (!buffer_jbd(bh)) 1250 goto not_jbd; 1251 jh = bh2jh(bh); 1252 1253 /* Critical error: attempting to delete a bitmap buffer, maybe? 1254 * Don't do any jbd operations, and return an error. */ 1255 if (!J_EXPECT_JH(jh, !jh->b_committed_data, 1256 "inconsistent data on disk")) { 1257 err = -EIO; 1258 goto not_jbd; 1259 } 1260 1261 /* keep track of whether or not this transaction modified us */ 1262 was_modified = jh->b_modified; 1263 1264 /* 1265 * The buffer's going from the transaction, we must drop 1266 * all references -bzzz 1267 */ 1268 jh->b_modified = 0; 1269 1270 if (jh->b_transaction == handle->h_transaction) { 1271 J_ASSERT_JH(jh, !jh->b_frozen_data); 1272 1273 /* If we are forgetting a buffer which is already part 1274 * of this transaction, then we can just drop it from 1275 * the transaction immediately. */ 1276 clear_buffer_dirty(bh); 1277 clear_buffer_jbddirty(bh); 1278 1279 JBUFFER_TRACE(jh, "belongs to current transaction: unfile"); 1280 1281 /* 1282 * we only want to drop a reference if this transaction 1283 * modified the buffer 1284 */ 1285 if (was_modified) 1286 drop_reserve = 1; 1287 1288 /* 1289 * We are no longer going to journal this buffer. 1290 * However, the commit of this transaction is still 1291 * important to the buffer: the delete that we are now 1292 * processing might obsolete an old log entry, so by 1293 * committing, we can satisfy the buffer's checkpoint. 1294 * 1295 * So, if we have a checkpoint on the buffer, we should 1296 * now refile the buffer on our BJ_Forget list so that 1297 * we know to remove the checkpoint after we commit. 1298 */ 1299 1300 if (jh->b_cp_transaction) { 1301 __journal_temp_unlink_buffer(jh); 1302 __journal_file_buffer(jh, transaction, BJ_Forget); 1303 } else { 1304 __journal_unfile_buffer(jh); 1305 if (!buffer_jbd(bh)) { 1306 spin_unlock(&journal->j_list_lock); 1307 jbd_unlock_bh_state(bh); 1308 __bforget(bh); 1309 goto drop; 1310 } 1311 } 1312 } else if (jh->b_transaction) { 1313 J_ASSERT_JH(jh, (jh->b_transaction == 1314 journal->j_committing_transaction)); 1315 /* However, if the buffer is still owned by a prior 1316 * (committing) transaction, we can't drop it yet... */ 1317 JBUFFER_TRACE(jh, "belongs to older transaction"); 1318 /* ... but we CAN drop it from the new transaction if we 1319 * have also modified it since the original commit. */ 1320 1321 if (jh->b_next_transaction) { 1322 J_ASSERT(jh->b_next_transaction == transaction); 1323 jh->b_next_transaction = NULL; 1324 1325 /* 1326 * only drop a reference if this transaction modified 1327 * the buffer 1328 */ 1329 if (was_modified) 1330 drop_reserve = 1; 1331 } 1332 } 1333 1334not_jbd: 1335 spin_unlock(&journal->j_list_lock); 1336 jbd_unlock_bh_state(bh); 1337 __brelse(bh); 1338drop: 1339 if (drop_reserve) { 1340 /* no need to reserve log space for this block -bzzz */ 1341 handle->h_buffer_credits++; 1342 } 1343 return err; 1344} 1345 1346/** 1347 * int journal_stop() - complete a transaction 1348 * @handle: tranaction to complete. 1349 * 1350 * All done for a particular handle. 1351 * 1352 * There is not much action needed here. We just return any remaining 1353 * buffer credits to the transaction and remove the handle. The only 1354 * complication is that we need to start a commit operation if the 1355 * filesystem is marked for synchronous update. 1356 * 1357 * journal_stop itself will not usually return an error, but it may 1358 * do so in unusual circumstances. In particular, expect it to 1359 * return -EIO if a journal_abort has been executed since the 1360 * transaction began. 1361 */ 1362int journal_stop(handle_t *handle) 1363{ 1364 transaction_t *transaction = handle->h_transaction; 1365 journal_t *journal = transaction->t_journal; 1366 int err; 1367 pid_t pid; 1368 1369 J_ASSERT(journal_current_handle() == handle); 1370 1371 if (is_handle_aborted(handle)) 1372 err = -EIO; 1373 else { 1374 J_ASSERT(transaction->t_updates > 0); 1375 err = 0; 1376 } 1377 1378 if (--handle->h_ref > 0) { 1379 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1, 1380 handle->h_ref); 1381 return err; 1382 } 1383 1384 jbd_debug(4, "Handle %p going down\n", handle); 1385 1386 /* 1387 * Implement synchronous transaction batching. If the handle 1388 * was synchronous, don't force a commit immediately. Let's 1389 * yield and let another thread piggyback onto this transaction. 1390 * Keep doing that while new threads continue to arrive. 1391 * It doesn't cost much - we're about to run a commit and sleep 1392 * on IO anyway. Speeds up many-threaded, many-dir operations 1393 * by 30x or more... 1394 * 1395 * We try and optimize the sleep time against what the underlying disk 1396 * can do, instead of having a static sleep time. This is useful for 1397 * the case where our storage is so fast that it is more optimal to go 1398 * ahead and force a flush and wait for the transaction to be committed 1399 * than it is to wait for an arbitrary amount of time for new writers to 1400 * join the transaction. We achieve this by measuring how long it takes 1401 * to commit a transaction, and compare it with how long this 1402 * transaction has been running, and if run time < commit time then we 1403 * sleep for the delta and commit. This greatly helps super fast disks 1404 * that would see slowdowns as more threads started doing fsyncs. 1405 * 1406 * But don't do this if this process was the most recent one to 1407 * perform a synchronous write. We do this to detect the case where a 1408 * single process is doing a stream of sync writes. No point in waiting 1409 * for joiners in that case. 1410 */ 1411 pid = current->pid; 1412 if (handle->h_sync && journal->j_last_sync_writer != pid) { 1413 u64 commit_time, trans_time; 1414 1415 journal->j_last_sync_writer = pid; 1416 1417 spin_lock(&journal->j_state_lock); 1418 commit_time = journal->j_average_commit_time; 1419 spin_unlock(&journal->j_state_lock); 1420 1421 trans_time = ktime_to_ns(ktime_sub(ktime_get(), 1422 transaction->t_start_time)); 1423 1424 commit_time = min_t(u64, commit_time, 1425 1000*jiffies_to_usecs(1)); 1426 1427 if (trans_time < commit_time) { 1428 ktime_t expires = ktime_add_ns(ktime_get(), 1429 commit_time); 1430 set_current_state(TASK_UNINTERRUPTIBLE); 1431 schedule_hrtimeout(&expires, HRTIMER_MODE_ABS); 1432 } 1433 } 1434 1435 current->journal_info = NULL; 1436 spin_lock(&journal->j_state_lock); 1437 spin_lock(&transaction->t_handle_lock); 1438 transaction->t_outstanding_credits -= handle->h_buffer_credits; 1439 transaction->t_updates--; 1440 if (!transaction->t_updates) { 1441 wake_up(&journal->j_wait_updates); 1442 if (journal->j_barrier_count) 1443 wake_up(&journal->j_wait_transaction_locked); 1444 } 1445 1446 /* 1447 * If the handle is marked SYNC, we need to set another commit 1448 * going! We also want to force a commit if the current 1449 * transaction is occupying too much of the log, or if the 1450 * transaction is too old now. 1451 */ 1452 if (handle->h_sync || 1453 transaction->t_outstanding_credits > 1454 journal->j_max_transaction_buffers || 1455 time_after_eq(jiffies, transaction->t_expires)) { 1456 /* Do this even for aborted journals: an abort still 1457 * completes the commit thread, it just doesn't write 1458 * anything to disk. */ 1459 tid_t tid = transaction->t_tid; 1460 1461 spin_unlock(&transaction->t_handle_lock); 1462 jbd_debug(2, "transaction too old, requesting commit for " 1463 "handle %p\n", handle); 1464 /* This is non-blocking */ 1465 __log_start_commit(journal, transaction->t_tid); 1466 spin_unlock(&journal->j_state_lock); 1467 1468 /* 1469 * Special case: JFS_SYNC synchronous updates require us 1470 * to wait for the commit to complete. 1471 */ 1472 if (handle->h_sync && !(current->flags & PF_MEMALLOC)) 1473 err = log_wait_commit(journal, tid); 1474 } else { 1475 spin_unlock(&transaction->t_handle_lock); 1476 spin_unlock(&journal->j_state_lock); 1477 } 1478 1479 lock_map_release(&handle->h_lockdep_map); 1480 1481 jbd_free_handle(handle); 1482 return err; 1483} 1484 1485/** 1486 * int journal_force_commit() - force any uncommitted transactions 1487 * @journal: journal to force 1488 * 1489 * For synchronous operations: force any uncommitted transactions 1490 * to disk. May seem kludgy, but it reuses all the handle batching 1491 * code in a very simple manner. 1492 */ 1493int journal_force_commit(journal_t *journal) 1494{ 1495 handle_t *handle; 1496 int ret; 1497 1498 handle = journal_start(journal, 1); 1499 if (IS_ERR(handle)) { 1500 ret = PTR_ERR(handle); 1501 } else { 1502 handle->h_sync = 1; 1503 ret = journal_stop(handle); 1504 } 1505 return ret; 1506} 1507 1508/* 1509 * 1510 * List management code snippets: various functions for manipulating the 1511 * transaction buffer lists. 1512 * 1513 */ 1514 1515/* 1516 * Append a buffer to a transaction list, given the transaction's list head 1517 * pointer. 1518 * 1519 * j_list_lock is held. 1520 * 1521 * jbd_lock_bh_state(jh2bh(jh)) is held. 1522 */ 1523 1524static inline void 1525__blist_add_buffer(struct journal_head **list, struct journal_head *jh) 1526{ 1527 if (!*list) { 1528 jh->b_tnext = jh->b_tprev = jh; 1529 *list = jh; 1530 } else { 1531 /* Insert at the tail of the list to preserve order */ 1532 struct journal_head *first = *list, *last = first->b_tprev; 1533 jh->b_tprev = last; 1534 jh->b_tnext = first; 1535 last->b_tnext = first->b_tprev = jh; 1536 } 1537} 1538 1539/* 1540 * Remove a buffer from a transaction list, given the transaction's list 1541 * head pointer. 1542 * 1543 * Called with j_list_lock held, and the journal may not be locked. 1544 * 1545 * jbd_lock_bh_state(jh2bh(jh)) is held. 1546 */ 1547 1548static inline void 1549__blist_del_buffer(struct journal_head **list, struct journal_head *jh) 1550{ 1551 if (*list == jh) { 1552 *list = jh->b_tnext; 1553 if (*list == jh) 1554 *list = NULL; 1555 } 1556 jh->b_tprev->b_tnext = jh->b_tnext; 1557 jh->b_tnext->b_tprev = jh->b_tprev; 1558} 1559 1560/* 1561 * Remove a buffer from the appropriate transaction list. 1562 * 1563 * Note that this function can *change* the value of 1564 * bh->b_transaction->t_sync_datalist, t_buffers, t_forget, 1565 * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller 1566 * is holding onto a copy of one of thee pointers, it could go bad. 1567 * Generally the caller needs to re-read the pointer from the transaction_t. 1568 * 1569 * Called under j_list_lock. The journal may not be locked. 1570 */ 1571static void __journal_temp_unlink_buffer(struct journal_head *jh) 1572{ 1573 struct journal_head **list = NULL; 1574 transaction_t *transaction; 1575 struct buffer_head *bh = jh2bh(jh); 1576 1577 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); 1578 transaction = jh->b_transaction; 1579 if (transaction) 1580 assert_spin_locked(&transaction->t_journal->j_list_lock); 1581 1582 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types); 1583 if (jh->b_jlist != BJ_None) 1584 J_ASSERT_JH(jh, transaction != NULL); 1585 1586 switch (jh->b_jlist) { 1587 case BJ_None: 1588 return; 1589 case BJ_SyncData: 1590 list = &transaction->t_sync_datalist; 1591 break; 1592 case BJ_Metadata: 1593 transaction->t_nr_buffers--; 1594 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0); 1595 list = &transaction->t_buffers; 1596 break; 1597 case BJ_Forget: 1598 list = &transaction->t_forget; 1599 break; 1600 case BJ_IO: 1601 list = &transaction->t_iobuf_list; 1602 break; 1603 case BJ_Shadow: 1604 list = &transaction->t_shadow_list; 1605 break; 1606 case BJ_LogCtl: 1607 list = &transaction->t_log_list; 1608 break; 1609 case BJ_Reserved: 1610 list = &transaction->t_reserved_list; 1611 break; 1612 case BJ_Locked: 1613 list = &transaction->t_locked_list; 1614 break; 1615 } 1616 1617 __blist_del_buffer(list, jh); 1618 jh->b_jlist = BJ_None; 1619 if (test_clear_buffer_jbddirty(bh)) 1620 mark_buffer_dirty(bh); /* Expose it to the VM */ 1621} 1622 1623/* 1624 * Remove buffer from all transactions. 1625 * 1626 * Called with bh_state lock and j_list_lock 1627 * 1628 * jh and bh may be already freed when this function returns. 1629 */ 1630void __journal_unfile_buffer(struct journal_head *jh) 1631{ 1632 __journal_temp_unlink_buffer(jh); 1633 jh->b_transaction = NULL; 1634 journal_put_journal_head(jh); 1635} 1636 1637void journal_unfile_buffer(journal_t *journal, struct journal_head *jh) 1638{ 1639 struct buffer_head *bh = jh2bh(jh); 1640 1641 /* Get reference so that buffer cannot be freed before we unlock it */ 1642 get_bh(bh); 1643 jbd_lock_bh_state(bh); 1644 spin_lock(&journal->j_list_lock); 1645 __journal_unfile_buffer(jh); 1646 spin_unlock(&journal->j_list_lock); 1647 jbd_unlock_bh_state(bh); 1648 __brelse(bh); 1649} 1650 1651/* 1652 * Called from journal_try_to_free_buffers(). 1653 * 1654 * Called under jbd_lock_bh_state(bh) 1655 */ 1656static void 1657__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh) 1658{ 1659 struct journal_head *jh; 1660 1661 jh = bh2jh(bh); 1662 1663 if (buffer_locked(bh) || buffer_dirty(bh)) 1664 goto out; 1665 1666 if (jh->b_next_transaction != NULL) 1667 goto out; 1668 1669 spin_lock(&journal->j_list_lock); 1670 if (jh->b_transaction != NULL && jh->b_cp_transaction == NULL) { 1671 if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) { 1672 /* A written-back ordered data buffer */ 1673 JBUFFER_TRACE(jh, "release data"); 1674 __journal_unfile_buffer(jh); 1675 } 1676 } else if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) { 1677 /* written-back checkpointed metadata buffer */ 1678 if (jh->b_jlist == BJ_None) { 1679 JBUFFER_TRACE(jh, "remove from checkpoint list"); 1680 __journal_remove_checkpoint(jh); 1681 } 1682 } 1683 spin_unlock(&journal->j_list_lock); 1684out: 1685 return; 1686} 1687 1688/** 1689 * int journal_try_to_free_buffers() - try to free page buffers. 1690 * @journal: journal for operation 1691 * @page: to try and free 1692 * @gfp_mask: we use the mask to detect how hard should we try to release 1693 * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to 1694 * release the buffers. 1695 * 1696 * 1697 * For all the buffers on this page, 1698 * if they are fully written out ordered data, move them onto BUF_CLEAN 1699 * so try_to_free_buffers() can reap them. 1700 * 1701 * This function returns non-zero if we wish try_to_free_buffers() 1702 * to be called. We do this if the page is releasable by try_to_free_buffers(). 1703 * We also do it if the page has locked or dirty buffers and the caller wants 1704 * us to perform sync or async writeout. 1705 * 1706 * This complicates JBD locking somewhat. We aren't protected by the 1707 * BKL here. We wish to remove the buffer from its committing or 1708 * running transaction's ->t_datalist via __journal_unfile_buffer. 1709 * 1710 * This may *change* the value of transaction_t->t_datalist, so anyone 1711 * who looks at t_datalist needs to lock against this function. 1712 * 1713 * Even worse, someone may be doing a journal_dirty_data on this 1714 * buffer. So we need to lock against that. journal_dirty_data() 1715 * will come out of the lock with the buffer dirty, which makes it 1716 * ineligible for release here. 1717 * 1718 * Who else is affected by this? hmm... Really the only contender 1719 * is do_get_write_access() - it could be looking at the buffer while 1720 * journal_try_to_free_buffer() is changing its state. But that 1721 * cannot happen because we never reallocate freed data as metadata 1722 * while the data is part of a transaction. Yes? 1723 * 1724 * Return 0 on failure, 1 on success 1725 */ 1726int journal_try_to_free_buffers(journal_t *journal, 1727 struct page *page, gfp_t gfp_mask) 1728{ 1729 struct buffer_head *head; 1730 struct buffer_head *bh; 1731 int ret = 0; 1732 1733 J_ASSERT(PageLocked(page)); 1734 1735 head = page_buffers(page); 1736 bh = head; 1737 do { 1738 struct journal_head *jh; 1739 1740 /* 1741 * We take our own ref against the journal_head here to avoid 1742 * having to add tons of locking around each instance of 1743 * journal_put_journal_head(). 1744 */ 1745 jh = journal_grab_journal_head(bh); 1746 if (!jh) 1747 continue; 1748 1749 jbd_lock_bh_state(bh); 1750 __journal_try_to_free_buffer(journal, bh); 1751 journal_put_journal_head(jh); 1752 jbd_unlock_bh_state(bh); 1753 if (buffer_jbd(bh)) 1754 goto busy; 1755 } while ((bh = bh->b_this_page) != head); 1756 1757 ret = try_to_free_buffers(page); 1758 1759busy: 1760 return ret; 1761} 1762 1763/* 1764 * This buffer is no longer needed. If it is on an older transaction's 1765 * checkpoint list we need to record it on this transaction's forget list 1766 * to pin this buffer (and hence its checkpointing transaction) down until 1767 * this transaction commits. If the buffer isn't on a checkpoint list, we 1768 * release it. 1769 * Returns non-zero if JBD no longer has an interest in the buffer. 1770 * 1771 * Called under j_list_lock. 1772 * 1773 * Called under jbd_lock_bh_state(bh). 1774 */ 1775static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction) 1776{ 1777 int may_free = 1; 1778 struct buffer_head *bh = jh2bh(jh); 1779 1780 if (jh->b_cp_transaction) { 1781 JBUFFER_TRACE(jh, "on running+cp transaction"); 1782 __journal_temp_unlink_buffer(jh); 1783 /* 1784 * We don't want to write the buffer anymore, clear the 1785 * bit so that we don't confuse checks in 1786 * __journal_file_buffer 1787 */ 1788 clear_buffer_dirty(bh); 1789 __journal_file_buffer(jh, transaction, BJ_Forget); 1790 may_free = 0; 1791 } else { 1792 JBUFFER_TRACE(jh, "on running transaction"); 1793 __journal_unfile_buffer(jh); 1794 } 1795 return may_free; 1796} 1797 1798/* 1799 * journal_invalidatepage 1800 * 1801 * This code is tricky. It has a number of cases to deal with. 1802 * 1803 * There are two invariants which this code relies on: 1804 * 1805 * i_size must be updated on disk before we start calling invalidatepage on the 1806 * data. 1807 * 1808 * This is done in ext3 by defining an ext3_setattr method which 1809 * updates i_size before truncate gets going. By maintaining this 1810 * invariant, we can be sure that it is safe to throw away any buffers 1811 * attached to the current transaction: once the transaction commits, 1812 * we know that the data will not be needed. 1813 * 1814 * Note however that we can *not* throw away data belonging to the 1815 * previous, committing transaction! 1816 * 1817 * Any disk blocks which *are* part of the previous, committing 1818 * transaction (and which therefore cannot be discarded immediately) are 1819 * not going to be reused in the new running transaction 1820 * 1821 * The bitmap committed_data images guarantee this: any block which is 1822 * allocated in one transaction and removed in the next will be marked 1823 * as in-use in the committed_data bitmap, so cannot be reused until 1824 * the next transaction to delete the block commits. This means that 1825 * leaving committing buffers dirty is quite safe: the disk blocks 1826 * cannot be reallocated to a different file and so buffer aliasing is 1827 * not possible. 1828 * 1829 * 1830 * The above applies mainly to ordered data mode. In writeback mode we 1831 * don't make guarantees about the order in which data hits disk --- in 1832 * particular we don't guarantee that new dirty data is flushed before 1833 * transaction commit --- so it is always safe just to discard data 1834 * immediately in that mode. --sct 1835 */ 1836 1837/* 1838 * The journal_unmap_buffer helper function returns zero if the buffer 1839 * concerned remains pinned as an anonymous buffer belonging to an older 1840 * transaction. 1841 * 1842 * We're outside-transaction here. Either or both of j_running_transaction 1843 * and j_committing_transaction may be NULL. 1844 */ 1845static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh, 1846 int partial_page) 1847{ 1848 transaction_t *transaction; 1849 struct journal_head *jh; 1850 int may_free = 1; 1851 1852 BUFFER_TRACE(bh, "entry"); 1853 1854retry: 1855 /* 1856 * It is safe to proceed here without the j_list_lock because the 1857 * buffers cannot be stolen by try_to_free_buffers as long as we are 1858 * holding the page lock. --sct 1859 */ 1860 1861 if (!buffer_jbd(bh)) 1862 goto zap_buffer_unlocked; 1863 1864 spin_lock(&journal->j_state_lock); 1865 jbd_lock_bh_state(bh); 1866 spin_lock(&journal->j_list_lock); 1867 1868 jh = journal_grab_journal_head(bh); 1869 if (!jh) 1870 goto zap_buffer_no_jh; 1871 1872 /* 1873 * We cannot remove the buffer from checkpoint lists until the 1874 * transaction adding inode to orphan list (let's call it T) 1875 * is committed. Otherwise if the transaction changing the 1876 * buffer would be cleaned from the journal before T is 1877 * committed, a crash will cause that the correct contents of 1878 * the buffer will be lost. On the other hand we have to 1879 * clear the buffer dirty bit at latest at the moment when the 1880 * transaction marking the buffer as freed in the filesystem 1881 * structures is committed because from that moment on the 1882 * block can be reallocated and used by a different page. 1883 * Since the block hasn't been freed yet but the inode has 1884 * already been added to orphan list, it is safe for us to add 1885 * the buffer to BJ_Forget list of the newest transaction. 1886 * 1887 * Also we have to clear buffer_mapped flag of a truncated buffer 1888 * because the buffer_head may be attached to the page straddling 1889 * i_size (can happen only when blocksize < pagesize) and thus the 1890 * buffer_head can be reused when the file is extended again. So we end 1891 * up keeping around invalidated buffers attached to transactions' 1892 * BJ_Forget list just to stop checkpointing code from cleaning up 1893 * the transaction this buffer was modified in. 1894 */ 1895 transaction = jh->b_transaction; 1896 if (transaction == NULL) { 1897 /* First case: not on any transaction. If it 1898 * has no checkpoint link, then we can zap it: 1899 * it's a writeback-mode buffer so we don't care 1900 * if it hits disk safely. */ 1901 if (!jh->b_cp_transaction) { 1902 JBUFFER_TRACE(jh, "not on any transaction: zap"); 1903 goto zap_buffer; 1904 } 1905 1906 if (!buffer_dirty(bh)) { 1907 /* bdflush has written it. We can drop it now */ 1908 goto zap_buffer; 1909 } 1910 1911 /* OK, it must be in the journal but still not 1912 * written fully to disk: it's metadata or 1913 * journaled data... */ 1914 1915 if (journal->j_running_transaction) { 1916 /* ... and once the current transaction has 1917 * committed, the buffer won't be needed any 1918 * longer. */ 1919 JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget"); 1920 may_free = __dispose_buffer(jh, 1921 journal->j_running_transaction); 1922 goto zap_buffer; 1923 } else { 1924 /* There is no currently-running transaction. So the 1925 * orphan record which we wrote for this file must have 1926 * passed into commit. We must attach this buffer to 1927 * the committing transaction, if it exists. */ 1928 if (journal->j_committing_transaction) { 1929 JBUFFER_TRACE(jh, "give to committing trans"); 1930 may_free = __dispose_buffer(jh, 1931 journal->j_committing_transaction); 1932 goto zap_buffer; 1933 } else { 1934 /* The orphan record's transaction has 1935 * committed. We can cleanse this buffer */ 1936 clear_buffer_jbddirty(bh); 1937 goto zap_buffer; 1938 } 1939 } 1940 } else if (transaction == journal->j_committing_transaction) { 1941 JBUFFER_TRACE(jh, "on committing transaction"); 1942 if (jh->b_jlist == BJ_Locked) { 1943 /* 1944 * The buffer is on the committing transaction's locked 1945 * list. We have the buffer locked, so I/O has 1946 * completed. So we can nail the buffer now. 1947 */ 1948 may_free = __dispose_buffer(jh, transaction); 1949 goto zap_buffer; 1950 } 1951 /* 1952 * The buffer is committing, we simply cannot touch 1953 * it. If the page is straddling i_size we have to wait 1954 * for commit and try again. 1955 */ 1956 if (partial_page) { 1957 tid_t tid = journal->j_committing_transaction->t_tid; 1958 1959 journal_put_journal_head(jh); 1960 spin_unlock(&journal->j_list_lock); 1961 jbd_unlock_bh_state(bh); 1962 spin_unlock(&journal->j_state_lock); 1963 unlock_buffer(bh); 1964 log_wait_commit(journal, tid); 1965 lock_buffer(bh); 1966 goto retry; 1967 } 1968 /* 1969 * OK, buffer won't be reachable after truncate. We just set 1970 * j_next_transaction to the running transaction (if there is 1971 * one) and mark buffer as freed so that commit code knows it 1972 * should clear dirty bits when it is done with the buffer. 1973 */ 1974 set_buffer_freed(bh); 1975 if (journal->j_running_transaction && buffer_jbddirty(bh)) 1976 jh->b_next_transaction = journal->j_running_transaction; 1977 journal_put_journal_head(jh); 1978 spin_unlock(&journal->j_list_lock); 1979 jbd_unlock_bh_state(bh); 1980 spin_unlock(&journal->j_state_lock); 1981 return 0; 1982 } else { 1983 /* Good, the buffer belongs to the running transaction. 1984 * We are writing our own transaction's data, not any 1985 * previous one's, so it is safe to throw it away 1986 * (remember that we expect the filesystem to have set 1987 * i_size already for this truncate so recovery will not 1988 * expose the disk blocks we are discarding here.) */ 1989 J_ASSERT_JH(jh, transaction == journal->j_running_transaction); 1990 JBUFFER_TRACE(jh, "on running transaction"); 1991 may_free = __dispose_buffer(jh, transaction); 1992 } 1993 1994zap_buffer: 1995 /* 1996 * This is tricky. Although the buffer is truncated, it may be reused 1997 * if blocksize < pagesize and it is attached to the page straddling 1998 * EOF. Since the buffer might have been added to BJ_Forget list of the 1999 * running transaction, journal_get_write_access() won't clear 2000 * b_modified and credit accounting gets confused. So clear b_modified 2001 * here. */ 2002 jh->b_modified = 0; 2003 journal_put_journal_head(jh); 2004zap_buffer_no_jh: 2005 spin_unlock(&journal->j_list_lock); 2006 jbd_unlock_bh_state(bh); 2007 spin_unlock(&journal->j_state_lock); 2008zap_buffer_unlocked: 2009 clear_buffer_dirty(bh); 2010 J_ASSERT_BH(bh, !buffer_jbddirty(bh)); 2011 clear_buffer_mapped(bh); 2012 clear_buffer_req(bh); 2013 clear_buffer_new(bh); 2014 bh->b_bdev = NULL; 2015 return may_free; 2016} 2017 2018/** 2019 * void journal_invalidatepage() - invalidate a journal page 2020 * @journal: journal to use for flush 2021 * @page: page to flush 2022 * @offset: offset of the range to invalidate 2023 * @length: length of the range to invalidate 2024 * 2025 * Reap page buffers containing data in specified range in page. 2026 */ 2027void journal_invalidatepage(journal_t *journal, 2028 struct page *page, 2029 unsigned int offset, 2030 unsigned int length) 2031{ 2032 struct buffer_head *head, *bh, *next; 2033 unsigned int stop = offset + length; 2034 unsigned int curr_off = 0; 2035 int partial_page = (offset || length < PAGE_CACHE_SIZE); 2036 int may_free = 1; 2037 2038 if (!PageLocked(page)) 2039 BUG(); 2040 if (!page_has_buffers(page)) 2041 return; 2042 2043 BUG_ON(stop > PAGE_CACHE_SIZE || stop < length); 2044 2045 /* We will potentially be playing with lists other than just the 2046 * data lists (especially for journaled data mode), so be 2047 * cautious in our locking. */ 2048 2049 head = bh = page_buffers(page); 2050 do { 2051 unsigned int next_off = curr_off + bh->b_size; 2052 next = bh->b_this_page; 2053 2054 if (next_off > stop) 2055 return; 2056 2057 if (offset <= curr_off) { 2058 /* This block is wholly outside the truncation point */ 2059 lock_buffer(bh); 2060 may_free &= journal_unmap_buffer(journal, bh, 2061 partial_page); 2062 unlock_buffer(bh); 2063 } 2064 curr_off = next_off; 2065 bh = next; 2066 2067 } while (bh != head); 2068 2069 if (!partial_page) { 2070 if (may_free && try_to_free_buffers(page)) 2071 J_ASSERT(!page_has_buffers(page)); 2072 } 2073} 2074 2075/* 2076 * File a buffer on the given transaction list. 2077 */ 2078void __journal_file_buffer(struct journal_head *jh, 2079 transaction_t *transaction, int jlist) 2080{ 2081 struct journal_head **list = NULL; 2082 int was_dirty = 0; 2083 struct buffer_head *bh = jh2bh(jh); 2084 2085 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); 2086 assert_spin_locked(&transaction->t_journal->j_list_lock); 2087 2088 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types); 2089 J_ASSERT_JH(jh, jh->b_transaction == transaction || 2090 jh->b_transaction == NULL); 2091 2092 if (jh->b_transaction && jh->b_jlist == jlist) 2093 return; 2094 2095 if (jlist == BJ_Metadata || jlist == BJ_Reserved || 2096 jlist == BJ_Shadow || jlist == BJ_Forget) { 2097 /* 2098 * For metadata buffers, we track dirty bit in buffer_jbddirty 2099 * instead of buffer_dirty. We should not see a dirty bit set 2100 * here because we clear it in do_get_write_access but e.g. 2101 * tune2fs can modify the sb and set the dirty bit at any time 2102 * so we try to gracefully handle that. 2103 */ 2104 if (buffer_dirty(bh)) 2105 warn_dirty_buffer(bh); 2106 if (test_clear_buffer_dirty(bh) || 2107 test_clear_buffer_jbddirty(bh)) 2108 was_dirty = 1; 2109 } 2110 2111 if (jh->b_transaction) 2112 __journal_temp_unlink_buffer(jh); 2113 else 2114 journal_grab_journal_head(bh); 2115 jh->b_transaction = transaction; 2116 2117 switch (jlist) { 2118 case BJ_None: 2119 J_ASSERT_JH(jh, !jh->b_committed_data); 2120 J_ASSERT_JH(jh, !jh->b_frozen_data); 2121 return; 2122 case BJ_SyncData: 2123 list = &transaction->t_sync_datalist; 2124 break; 2125 case BJ_Metadata: 2126 transaction->t_nr_buffers++; 2127 list = &transaction->t_buffers; 2128 break; 2129 case BJ_Forget: 2130 list = &transaction->t_forget; 2131 break; 2132 case BJ_IO: 2133 list = &transaction->t_iobuf_list; 2134 break; 2135 case BJ_Shadow: 2136 list = &transaction->t_shadow_list; 2137 break; 2138 case BJ_LogCtl: 2139 list = &transaction->t_log_list; 2140 break; 2141 case BJ_Reserved: 2142 list = &transaction->t_reserved_list; 2143 break; 2144 case BJ_Locked: 2145 list = &transaction->t_locked_list; 2146 break; 2147 } 2148 2149 __blist_add_buffer(list, jh); 2150 jh->b_jlist = jlist; 2151 2152 if (was_dirty) 2153 set_buffer_jbddirty(bh); 2154} 2155 2156void journal_file_buffer(struct journal_head *jh, 2157 transaction_t *transaction, int jlist) 2158{ 2159 jbd_lock_bh_state(jh2bh(jh)); 2160 spin_lock(&transaction->t_journal->j_list_lock); 2161 __journal_file_buffer(jh, transaction, jlist); 2162 spin_unlock(&transaction->t_journal->j_list_lock); 2163 jbd_unlock_bh_state(jh2bh(jh)); 2164} 2165 2166/* 2167 * Remove a buffer from its current buffer list in preparation for 2168 * dropping it from its current transaction entirely. If the buffer has 2169 * already started to be used by a subsequent transaction, refile the 2170 * buffer on that transaction's metadata list. 2171 * 2172 * Called under j_list_lock 2173 * Called under jbd_lock_bh_state(jh2bh(jh)) 2174 * 2175 * jh and bh may be already free when this function returns 2176 */ 2177void __journal_refile_buffer(struct journal_head *jh) 2178{ 2179 int was_dirty, jlist; 2180 struct buffer_head *bh = jh2bh(jh); 2181 2182 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); 2183 if (jh->b_transaction) 2184 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock); 2185 2186 /* If the buffer is now unused, just drop it. */ 2187 if (jh->b_next_transaction == NULL) { 2188 __journal_unfile_buffer(jh); 2189 return; 2190 } 2191 2192 /* 2193 * It has been modified by a later transaction: add it to the new 2194 * transaction's metadata list. 2195 */ 2196 2197 was_dirty = test_clear_buffer_jbddirty(bh); 2198 __journal_temp_unlink_buffer(jh); 2199 /* 2200 * We set b_transaction here because b_next_transaction will inherit 2201 * our jh reference and thus __journal_file_buffer() must not take a 2202 * new one. 2203 */ 2204 jh->b_transaction = jh->b_next_transaction; 2205 jh->b_next_transaction = NULL; 2206 if (buffer_freed(bh)) 2207 jlist = BJ_Forget; 2208 else if (jh->b_modified) 2209 jlist = BJ_Metadata; 2210 else 2211 jlist = BJ_Reserved; 2212 __journal_file_buffer(jh, jh->b_transaction, jlist); 2213 J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING); 2214 2215 if (was_dirty) 2216 set_buffer_jbddirty(bh); 2217} 2218 2219/* 2220 * __journal_refile_buffer() with necessary locking added. We take our bh 2221 * reference so that we can safely unlock bh. 2222 * 2223 * The jh and bh may be freed by this call. 2224 */ 2225void journal_refile_buffer(journal_t *journal, struct journal_head *jh) 2226{ 2227 struct buffer_head *bh = jh2bh(jh); 2228 2229 /* Get reference so that buffer cannot be freed before we unlock it */ 2230 get_bh(bh); 2231 jbd_lock_bh_state(bh); 2232 spin_lock(&journal->j_list_lock); 2233 __journal_refile_buffer(jh); 2234 jbd_unlock_bh_state(bh); 2235 spin_unlock(&journal->j_list_lock); 2236 __brelse(bh); 2237} 2238