1 /* 2 * linux/fs/jbd2/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/jbd2.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 #include <linux/backing-dev.h> 30 #include <linux/module.h> 31 32 static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh); 33 34 /* 35 * jbd2_get_transaction: obtain a new transaction_t object. 36 * 37 * Simply allocate and initialise a new transaction. Create it in 38 * RUNNING state and add it to the current journal (which should not 39 * have an existing running transaction: we only make a new transaction 40 * once we have started to commit the old one). 41 * 42 * Preconditions: 43 * The journal MUST be locked. We don't perform atomic mallocs on the 44 * new transaction and we can't block without protecting against other 45 * processes trying to touch the journal while it is in transition. 46 * 47 */ 48 49 static transaction_t * 50 jbd2_get_transaction(journal_t *journal, transaction_t *transaction) 51 { 52 transaction->t_journal = journal; 53 transaction->t_state = T_RUNNING; 54 transaction->t_start_time = ktime_get(); 55 transaction->t_tid = journal->j_transaction_sequence++; 56 transaction->t_expires = jiffies + journal->j_commit_interval; 57 spin_lock_init(&transaction->t_handle_lock); 58 atomic_set(&transaction->t_updates, 0); 59 atomic_set(&transaction->t_outstanding_credits, 0); 60 atomic_set(&transaction->t_handle_count, 0); 61 INIT_LIST_HEAD(&transaction->t_inode_list); 62 INIT_LIST_HEAD(&transaction->t_private_list); 63 64 /* Set up the commit timer for the new transaction. */ 65 journal->j_commit_timer.expires = round_jiffies_up(transaction->t_expires); 66 add_timer(&journal->j_commit_timer); 67 68 J_ASSERT(journal->j_running_transaction == NULL); 69 journal->j_running_transaction = transaction; 70 transaction->t_max_wait = 0; 71 transaction->t_start = jiffies; 72 73 return transaction; 74 } 75 76 /* 77 * Handle management. 78 * 79 * A handle_t is an object which represents a single atomic update to a 80 * filesystem, and which tracks all of the modifications which form part 81 * of that one update. 82 */ 83 84 /* 85 * Update transiaction's maximum wait time, if debugging is enabled. 86 * 87 * In order for t_max_wait to be reliable, it must be protected by a 88 * lock. But doing so will mean that start_this_handle() can not be 89 * run in parallel on SMP systems, which limits our scalability. So 90 * unless debugging is enabled, we no longer update t_max_wait, which 91 * means that maximum wait time reported by the jbd2_run_stats 92 * tracepoint will always be zero. 93 */ 94 static inline void update_t_max_wait(transaction_t *transaction) 95 { 96 #ifdef CONFIG_JBD2_DEBUG 97 unsigned long ts = jiffies; 98 99 if (jbd2_journal_enable_debug && 100 time_after(transaction->t_start, ts)) { 101 ts = jbd2_time_diff(ts, transaction->t_start); 102 spin_lock(&transaction->t_handle_lock); 103 if (ts > transaction->t_max_wait) 104 transaction->t_max_wait = ts; 105 spin_unlock(&transaction->t_handle_lock); 106 } 107 #endif 108 } 109 110 /* 111 * start_this_handle: Given a handle, deal with any locking or stalling 112 * needed to make sure that there is enough journal space for the handle 113 * to begin. Attach the handle to a transaction and set up the 114 * transaction's buffer credits. 115 */ 116 117 static int start_this_handle(journal_t *journal, handle_t *handle, 118 int gfp_mask) 119 { 120 transaction_t *transaction; 121 int needed; 122 int nblocks = handle->h_buffer_credits; 123 transaction_t *new_transaction = NULL; 124 125 if (nblocks > journal->j_max_transaction_buffers) { 126 printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n", 127 current->comm, nblocks, 128 journal->j_max_transaction_buffers); 129 return -ENOSPC; 130 } 131 132 alloc_transaction: 133 if (!journal->j_running_transaction) { 134 new_transaction = kzalloc(sizeof(*new_transaction), gfp_mask); 135 if (!new_transaction) { 136 /* 137 * If __GFP_FS is not present, then we may be 138 * being called from inside the fs writeback 139 * layer, so we MUST NOT fail. Since 140 * __GFP_NOFAIL is going away, we will arrange 141 * to retry the allocation ourselves. 142 */ 143 if ((gfp_mask & __GFP_FS) == 0) { 144 congestion_wait(BLK_RW_ASYNC, HZ/50); 145 goto alloc_transaction; 146 } 147 return -ENOMEM; 148 } 149 } 150 151 jbd_debug(3, "New handle %p going live.\n", handle); 152 153 /* 154 * We need to hold j_state_lock until t_updates has been incremented, 155 * for proper journal barrier handling 156 */ 157 repeat: 158 read_lock(&journal->j_state_lock); 159 BUG_ON(journal->j_flags & JBD2_UNMOUNT); 160 if (is_journal_aborted(journal) || 161 (journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) { 162 read_unlock(&journal->j_state_lock); 163 kfree(new_transaction); 164 return -EROFS; 165 } 166 167 /* Wait on the journal's transaction barrier if necessary */ 168 if (journal->j_barrier_count) { 169 read_unlock(&journal->j_state_lock); 170 wait_event(journal->j_wait_transaction_locked, 171 journal->j_barrier_count == 0); 172 goto repeat; 173 } 174 175 if (!journal->j_running_transaction) { 176 read_unlock(&journal->j_state_lock); 177 if (!new_transaction) 178 goto alloc_transaction; 179 write_lock(&journal->j_state_lock); 180 if (!journal->j_running_transaction) { 181 jbd2_get_transaction(journal, new_transaction); 182 new_transaction = NULL; 183 } 184 write_unlock(&journal->j_state_lock); 185 goto repeat; 186 } 187 188 transaction = journal->j_running_transaction; 189 190 /* 191 * If the current transaction is locked down for commit, wait for the 192 * lock to be released. 193 */ 194 if (transaction->t_state == T_LOCKED) { 195 DEFINE_WAIT(wait); 196 197 prepare_to_wait(&journal->j_wait_transaction_locked, 198 &wait, TASK_UNINTERRUPTIBLE); 199 read_unlock(&journal->j_state_lock); 200 schedule(); 201 finish_wait(&journal->j_wait_transaction_locked, &wait); 202 goto repeat; 203 } 204 205 /* 206 * If there is not enough space left in the log to write all potential 207 * buffers requested by this operation, we need to stall pending a log 208 * checkpoint to free some more log space. 209 */ 210 needed = atomic_add_return(nblocks, 211 &transaction->t_outstanding_credits); 212 213 if (needed > journal->j_max_transaction_buffers) { 214 /* 215 * If the current transaction is already too large, then start 216 * to commit it: we can then go back and attach this handle to 217 * a new transaction. 218 */ 219 DEFINE_WAIT(wait); 220 221 jbd_debug(2, "Handle %p starting new commit...\n", handle); 222 atomic_sub(nblocks, &transaction->t_outstanding_credits); 223 prepare_to_wait(&journal->j_wait_transaction_locked, &wait, 224 TASK_UNINTERRUPTIBLE); 225 __jbd2_log_start_commit(journal, transaction->t_tid); 226 read_unlock(&journal->j_state_lock); 227 schedule(); 228 finish_wait(&journal->j_wait_transaction_locked, &wait); 229 goto repeat; 230 } 231 232 /* 233 * The commit code assumes that it can get enough log space 234 * without forcing a checkpoint. This is *critical* for 235 * correctness: a checkpoint of a buffer which is also 236 * associated with a committing transaction creates a deadlock, 237 * so commit simply cannot force through checkpoints. 238 * 239 * We must therefore ensure the necessary space in the journal 240 * *before* starting to dirty potentially checkpointed buffers 241 * in the new transaction. 242 * 243 * The worst part is, any transaction currently committing can 244 * reduce the free space arbitrarily. Be careful to account for 245 * those buffers when checkpointing. 246 */ 247 248 /* 249 * @@@ AKPM: This seems rather over-defensive. We're giving commit 250 * a _lot_ of headroom: 1/4 of the journal plus the size of 251 * the committing transaction. Really, we only need to give it 252 * committing_transaction->t_outstanding_credits plus "enough" for 253 * the log control blocks. 254 * Also, this test is inconsitent with the matching one in 255 * jbd2_journal_extend(). 256 */ 257 if (__jbd2_log_space_left(journal) < jbd_space_needed(journal)) { 258 jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle); 259 atomic_sub(nblocks, &transaction->t_outstanding_credits); 260 read_unlock(&journal->j_state_lock); 261 write_lock(&journal->j_state_lock); 262 if (__jbd2_log_space_left(journal) < jbd_space_needed(journal)) 263 __jbd2_log_wait_for_space(journal); 264 write_unlock(&journal->j_state_lock); 265 goto repeat; 266 } 267 268 /* OK, account for the buffers that this operation expects to 269 * use and add the handle to the running transaction. 270 */ 271 update_t_max_wait(transaction); 272 handle->h_transaction = transaction; 273 atomic_inc(&transaction->t_updates); 274 atomic_inc(&transaction->t_handle_count); 275 jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n", 276 handle, nblocks, 277 atomic_read(&transaction->t_outstanding_credits), 278 __jbd2_log_space_left(journal)); 279 read_unlock(&journal->j_state_lock); 280 281 lock_map_acquire(&handle->h_lockdep_map); 282 kfree(new_transaction); 283 return 0; 284 } 285 286 static struct lock_class_key jbd2_handle_key; 287 288 /* Allocate a new handle. This should probably be in a slab... */ 289 static handle_t *new_handle(int nblocks) 290 { 291 handle_t *handle = jbd2_alloc_handle(GFP_NOFS); 292 if (!handle) 293 return NULL; 294 memset(handle, 0, sizeof(*handle)); 295 handle->h_buffer_credits = nblocks; 296 handle->h_ref = 1; 297 298 lockdep_init_map(&handle->h_lockdep_map, "jbd2_handle", 299 &jbd2_handle_key, 0); 300 301 return handle; 302 } 303 304 /** 305 * handle_t *jbd2_journal_start() - Obtain a new handle. 306 * @journal: Journal to start transaction on. 307 * @nblocks: number of block buffer we might modify 308 * 309 * We make sure that the transaction can guarantee at least nblocks of 310 * modified buffers in the log. We block until the log can guarantee 311 * that much space. 312 * 313 * This function is visible to journal users (like ext3fs), so is not 314 * called with the journal already locked. 315 * 316 * Return a pointer to a newly allocated handle, or NULL on failure 317 */ 318 handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int gfp_mask) 319 { 320 handle_t *handle = journal_current_handle(); 321 int err; 322 323 if (!journal) 324 return ERR_PTR(-EROFS); 325 326 if (handle) { 327 J_ASSERT(handle->h_transaction->t_journal == journal); 328 handle->h_ref++; 329 return handle; 330 } 331 332 handle = new_handle(nblocks); 333 if (!handle) 334 return ERR_PTR(-ENOMEM); 335 336 current->journal_info = handle; 337 338 err = start_this_handle(journal, handle, gfp_mask); 339 if (err < 0) { 340 jbd2_free_handle(handle); 341 current->journal_info = NULL; 342 handle = ERR_PTR(err); 343 goto out; 344 } 345 out: 346 return handle; 347 } 348 EXPORT_SYMBOL(jbd2__journal_start); 349 350 351 handle_t *jbd2_journal_start(journal_t *journal, int nblocks) 352 { 353 return jbd2__journal_start(journal, nblocks, GFP_NOFS); 354 } 355 EXPORT_SYMBOL(jbd2_journal_start); 356 357 358 /** 359 * int jbd2_journal_extend() - extend buffer credits. 360 * @handle: handle to 'extend' 361 * @nblocks: nr blocks to try to extend by. 362 * 363 * Some transactions, such as large extends and truncates, can be done 364 * atomically all at once or in several stages. The operation requests 365 * a credit for a number of buffer modications in advance, but can 366 * extend its credit if it needs more. 367 * 368 * jbd2_journal_extend tries to give the running handle more buffer credits. 369 * It does not guarantee that allocation - this is a best-effort only. 370 * The calling process MUST be able to deal cleanly with a failure to 371 * extend here. 372 * 373 * Return 0 on success, non-zero on failure. 374 * 375 * return code < 0 implies an error 376 * return code > 0 implies normal transaction-full status. 377 */ 378 int jbd2_journal_extend(handle_t *handle, int nblocks) 379 { 380 transaction_t *transaction = handle->h_transaction; 381 journal_t *journal = transaction->t_journal; 382 int result; 383 int wanted; 384 385 result = -EIO; 386 if (is_handle_aborted(handle)) 387 goto out; 388 389 result = 1; 390 391 read_lock(&journal->j_state_lock); 392 393 /* Don't extend a locked-down transaction! */ 394 if (handle->h_transaction->t_state != T_RUNNING) { 395 jbd_debug(3, "denied handle %p %d blocks: " 396 "transaction not running\n", handle, nblocks); 397 goto error_out; 398 } 399 400 spin_lock(&transaction->t_handle_lock); 401 wanted = atomic_read(&transaction->t_outstanding_credits) + nblocks; 402 403 if (wanted > journal->j_max_transaction_buffers) { 404 jbd_debug(3, "denied handle %p %d blocks: " 405 "transaction too large\n", handle, nblocks); 406 goto unlock; 407 } 408 409 if (wanted > __jbd2_log_space_left(journal)) { 410 jbd_debug(3, "denied handle %p %d blocks: " 411 "insufficient log space\n", handle, nblocks); 412 goto unlock; 413 } 414 415 handle->h_buffer_credits += nblocks; 416 atomic_add(nblocks, &transaction->t_outstanding_credits); 417 result = 0; 418 419 jbd_debug(3, "extended handle %p by %d\n", handle, nblocks); 420 unlock: 421 spin_unlock(&transaction->t_handle_lock); 422 error_out: 423 read_unlock(&journal->j_state_lock); 424 out: 425 return result; 426 } 427 428 429 /** 430 * int jbd2_journal_restart() - restart a handle . 431 * @handle: handle to restart 432 * @nblocks: nr credits requested 433 * 434 * Restart a handle for a multi-transaction filesystem 435 * operation. 436 * 437 * If the jbd2_journal_extend() call above fails to grant new buffer credits 438 * to a running handle, a call to jbd2_journal_restart will commit the 439 * handle's transaction so far and reattach the handle to a new 440 * transaction capabable of guaranteeing the requested number of 441 * credits. 442 */ 443 int jbd2__journal_restart(handle_t *handle, int nblocks, int gfp_mask) 444 { 445 transaction_t *transaction = handle->h_transaction; 446 journal_t *journal = transaction->t_journal; 447 int ret; 448 449 /* If we've had an abort of any type, don't even think about 450 * actually doing the restart! */ 451 if (is_handle_aborted(handle)) 452 return 0; 453 454 /* 455 * First unlink the handle from its current transaction, and start the 456 * commit on that. 457 */ 458 J_ASSERT(atomic_read(&transaction->t_updates) > 0); 459 J_ASSERT(journal_current_handle() == handle); 460 461 read_lock(&journal->j_state_lock); 462 spin_lock(&transaction->t_handle_lock); 463 atomic_sub(handle->h_buffer_credits, 464 &transaction->t_outstanding_credits); 465 if (atomic_dec_and_test(&transaction->t_updates)) 466 wake_up(&journal->j_wait_updates); 467 spin_unlock(&transaction->t_handle_lock); 468 469 jbd_debug(2, "restarting handle %p\n", handle); 470 __jbd2_log_start_commit(journal, transaction->t_tid); 471 read_unlock(&journal->j_state_lock); 472 473 lock_map_release(&handle->h_lockdep_map); 474 handle->h_buffer_credits = nblocks; 475 ret = start_this_handle(journal, handle, gfp_mask); 476 return ret; 477 } 478 EXPORT_SYMBOL(jbd2__journal_restart); 479 480 481 int jbd2_journal_restart(handle_t *handle, int nblocks) 482 { 483 return jbd2__journal_restart(handle, nblocks, GFP_NOFS); 484 } 485 EXPORT_SYMBOL(jbd2_journal_restart); 486 487 /** 488 * void jbd2_journal_lock_updates () - establish a transaction barrier. 489 * @journal: Journal to establish a barrier on. 490 * 491 * This locks out any further updates from being started, and blocks 492 * until all existing updates have completed, returning only once the 493 * journal is in a quiescent state with no updates running. 494 * 495 * The journal lock should not be held on entry. 496 */ 497 void jbd2_journal_lock_updates(journal_t *journal) 498 { 499 DEFINE_WAIT(wait); 500 501 write_lock(&journal->j_state_lock); 502 ++journal->j_barrier_count; 503 504 /* Wait until there are no running updates */ 505 while (1) { 506 transaction_t *transaction = journal->j_running_transaction; 507 508 if (!transaction) 509 break; 510 511 spin_lock(&transaction->t_handle_lock); 512 if (!atomic_read(&transaction->t_updates)) { 513 spin_unlock(&transaction->t_handle_lock); 514 break; 515 } 516 prepare_to_wait(&journal->j_wait_updates, &wait, 517 TASK_UNINTERRUPTIBLE); 518 spin_unlock(&transaction->t_handle_lock); 519 write_unlock(&journal->j_state_lock); 520 schedule(); 521 finish_wait(&journal->j_wait_updates, &wait); 522 write_lock(&journal->j_state_lock); 523 } 524 write_unlock(&journal->j_state_lock); 525 526 /* 527 * We have now established a barrier against other normal updates, but 528 * we also need to barrier against other jbd2_journal_lock_updates() calls 529 * to make sure that we serialise special journal-locked operations 530 * too. 531 */ 532 mutex_lock(&journal->j_barrier); 533 } 534 535 /** 536 * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier 537 * @journal: Journal to release the barrier on. 538 * 539 * Release a transaction barrier obtained with jbd2_journal_lock_updates(). 540 * 541 * Should be called without the journal lock held. 542 */ 543 void jbd2_journal_unlock_updates (journal_t *journal) 544 { 545 J_ASSERT(journal->j_barrier_count != 0); 546 547 mutex_unlock(&journal->j_barrier); 548 write_lock(&journal->j_state_lock); 549 --journal->j_barrier_count; 550 write_unlock(&journal->j_state_lock); 551 wake_up(&journal->j_wait_transaction_locked); 552 } 553 554 static void warn_dirty_buffer(struct buffer_head *bh) 555 { 556 char b[BDEVNAME_SIZE]; 557 558 printk(KERN_WARNING 559 "JBD: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). " 560 "There's a risk of filesystem corruption in case of system " 561 "crash.\n", 562 bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr); 563 } 564 565 /* 566 * If the buffer is already part of the current transaction, then there 567 * is nothing we need to do. If it is already part of a prior 568 * transaction which we are still committing to disk, then we need to 569 * make sure that we do not overwrite the old copy: we do copy-out to 570 * preserve the copy going to disk. We also account the buffer against 571 * the handle's metadata buffer credits (unless the buffer is already 572 * part of the transaction, that is). 573 * 574 */ 575 static int 576 do_get_write_access(handle_t *handle, struct journal_head *jh, 577 int force_copy) 578 { 579 struct buffer_head *bh; 580 transaction_t *transaction; 581 journal_t *journal; 582 int error; 583 char *frozen_buffer = NULL; 584 int need_copy = 0; 585 586 if (is_handle_aborted(handle)) 587 return -EROFS; 588 589 transaction = handle->h_transaction; 590 journal = transaction->t_journal; 591 592 jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy); 593 594 JBUFFER_TRACE(jh, "entry"); 595 repeat: 596 bh = jh2bh(jh); 597 598 /* @@@ Need to check for errors here at some point. */ 599 600 lock_buffer(bh); 601 jbd_lock_bh_state(bh); 602 603 /* We now hold the buffer lock so it is safe to query the buffer 604 * state. Is the buffer dirty? 605 * 606 * If so, there are two possibilities. The buffer may be 607 * non-journaled, and undergoing a quite legitimate writeback. 608 * Otherwise, it is journaled, and we don't expect dirty buffers 609 * in that state (the buffers should be marked JBD_Dirty 610 * instead.) So either the IO is being done under our own 611 * control and this is a bug, or it's a third party IO such as 612 * dump(8) (which may leave the buffer scheduled for read --- 613 * ie. locked but not dirty) or tune2fs (which may actually have 614 * the buffer dirtied, ugh.) */ 615 616 if (buffer_dirty(bh)) { 617 /* 618 * First question: is this buffer already part of the current 619 * transaction or the existing committing transaction? 620 */ 621 if (jh->b_transaction) { 622 J_ASSERT_JH(jh, 623 jh->b_transaction == transaction || 624 jh->b_transaction == 625 journal->j_committing_transaction); 626 if (jh->b_next_transaction) 627 J_ASSERT_JH(jh, jh->b_next_transaction == 628 transaction); 629 warn_dirty_buffer(bh); 630 } 631 /* 632 * In any case we need to clean the dirty flag and we must 633 * do it under the buffer lock to be sure we don't race 634 * with running write-out. 635 */ 636 JBUFFER_TRACE(jh, "Journalling dirty buffer"); 637 clear_buffer_dirty(bh); 638 set_buffer_jbddirty(bh); 639 } 640 641 unlock_buffer(bh); 642 643 error = -EROFS; 644 if (is_handle_aborted(handle)) { 645 jbd_unlock_bh_state(bh); 646 goto out; 647 } 648 error = 0; 649 650 /* 651 * The buffer is already part of this transaction if b_transaction or 652 * b_next_transaction points to it 653 */ 654 if (jh->b_transaction == transaction || 655 jh->b_next_transaction == transaction) 656 goto done; 657 658 /* 659 * this is the first time this transaction is touching this buffer, 660 * reset the modified flag 661 */ 662 jh->b_modified = 0; 663 664 /* 665 * If there is already a copy-out version of this buffer, then we don't 666 * need to make another one 667 */ 668 if (jh->b_frozen_data) { 669 JBUFFER_TRACE(jh, "has frozen data"); 670 J_ASSERT_JH(jh, jh->b_next_transaction == NULL); 671 jh->b_next_transaction = transaction; 672 goto done; 673 } 674 675 /* Is there data here we need to preserve? */ 676 677 if (jh->b_transaction && jh->b_transaction != transaction) { 678 JBUFFER_TRACE(jh, "owned by older transaction"); 679 J_ASSERT_JH(jh, jh->b_next_transaction == NULL); 680 J_ASSERT_JH(jh, jh->b_transaction == 681 journal->j_committing_transaction); 682 683 /* There is one case we have to be very careful about. 684 * If the committing transaction is currently writing 685 * this buffer out to disk and has NOT made a copy-out, 686 * then we cannot modify the buffer contents at all 687 * right now. The essence of copy-out is that it is the 688 * extra copy, not the primary copy, which gets 689 * journaled. If the primary copy is already going to 690 * disk then we cannot do copy-out here. */ 691 692 if (jh->b_jlist == BJ_Shadow) { 693 DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow); 694 wait_queue_head_t *wqh; 695 696 wqh = bit_waitqueue(&bh->b_state, BH_Unshadow); 697 698 JBUFFER_TRACE(jh, "on shadow: sleep"); 699 jbd_unlock_bh_state(bh); 700 /* commit wakes up all shadow buffers after IO */ 701 for ( ; ; ) { 702 prepare_to_wait(wqh, &wait.wait, 703 TASK_UNINTERRUPTIBLE); 704 if (jh->b_jlist != BJ_Shadow) 705 break; 706 schedule(); 707 } 708 finish_wait(wqh, &wait.wait); 709 goto repeat; 710 } 711 712 /* Only do the copy if the currently-owning transaction 713 * still needs it. If it is on the Forget list, the 714 * committing transaction is past that stage. The 715 * buffer had better remain locked during the kmalloc, 716 * but that should be true --- we hold the journal lock 717 * still and the buffer is already on the BUF_JOURNAL 718 * list so won't be flushed. 719 * 720 * Subtle point, though: if this is a get_undo_access, 721 * then we will be relying on the frozen_data to contain 722 * the new value of the committed_data record after the 723 * transaction, so we HAVE to force the frozen_data copy 724 * in that case. */ 725 726 if (jh->b_jlist != BJ_Forget || force_copy) { 727 JBUFFER_TRACE(jh, "generate frozen data"); 728 if (!frozen_buffer) { 729 JBUFFER_TRACE(jh, "allocate memory for buffer"); 730 jbd_unlock_bh_state(bh); 731 frozen_buffer = 732 jbd2_alloc(jh2bh(jh)->b_size, 733 GFP_NOFS); 734 if (!frozen_buffer) { 735 printk(KERN_EMERG 736 "%s: OOM for frozen_buffer\n", 737 __func__); 738 JBUFFER_TRACE(jh, "oom!"); 739 error = -ENOMEM; 740 jbd_lock_bh_state(bh); 741 goto done; 742 } 743 goto repeat; 744 } 745 jh->b_frozen_data = frozen_buffer; 746 frozen_buffer = NULL; 747 need_copy = 1; 748 } 749 jh->b_next_transaction = transaction; 750 } 751 752 753 /* 754 * Finally, if the buffer is not journaled right now, we need to make 755 * sure it doesn't get written to disk before the caller actually 756 * commits the new data 757 */ 758 if (!jh->b_transaction) { 759 JBUFFER_TRACE(jh, "no transaction"); 760 J_ASSERT_JH(jh, !jh->b_next_transaction); 761 jh->b_transaction = transaction; 762 JBUFFER_TRACE(jh, "file as BJ_Reserved"); 763 spin_lock(&journal->j_list_lock); 764 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved); 765 spin_unlock(&journal->j_list_lock); 766 } 767 768 done: 769 if (need_copy) { 770 struct page *page; 771 int offset; 772 char *source; 773 774 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)), 775 "Possible IO failure.\n"); 776 page = jh2bh(jh)->b_page; 777 offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK; 778 source = kmap_atomic(page, KM_USER0); 779 /* Fire data frozen trigger just before we copy the data */ 780 jbd2_buffer_frozen_trigger(jh, source + offset, 781 jh->b_triggers); 782 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size); 783 kunmap_atomic(source, KM_USER0); 784 785 /* 786 * Now that the frozen data is saved off, we need to store 787 * any matching triggers. 788 */ 789 jh->b_frozen_triggers = jh->b_triggers; 790 } 791 jbd_unlock_bh_state(bh); 792 793 /* 794 * If we are about to journal a buffer, then any revoke pending on it is 795 * no longer valid 796 */ 797 jbd2_journal_cancel_revoke(handle, jh); 798 799 out: 800 if (unlikely(frozen_buffer)) /* It's usually NULL */ 801 jbd2_free(frozen_buffer, bh->b_size); 802 803 JBUFFER_TRACE(jh, "exit"); 804 return error; 805 } 806 807 /** 808 * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update. 809 * @handle: transaction to add buffer modifications to 810 * @bh: bh to be used for metadata writes 811 * @credits: variable that will receive credits for the buffer 812 * 813 * Returns an error code or 0 on success. 814 * 815 * In full data journalling mode the buffer may be of type BJ_AsyncData, 816 * because we're write()ing a buffer which is also part of a shared mapping. 817 */ 818 819 int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh) 820 { 821 struct journal_head *jh = jbd2_journal_add_journal_head(bh); 822 int rc; 823 824 /* We do not want to get caught playing with fields which the 825 * log thread also manipulates. Make sure that the buffer 826 * completes any outstanding IO before proceeding. */ 827 rc = do_get_write_access(handle, jh, 0); 828 jbd2_journal_put_journal_head(jh); 829 return rc; 830 } 831 832 833 /* 834 * When the user wants to journal a newly created buffer_head 835 * (ie. getblk() returned a new buffer and we are going to populate it 836 * manually rather than reading off disk), then we need to keep the 837 * buffer_head locked until it has been completely filled with new 838 * data. In this case, we should be able to make the assertion that 839 * the bh is not already part of an existing transaction. 840 * 841 * The buffer should already be locked by the caller by this point. 842 * There is no lock ranking violation: it was a newly created, 843 * unlocked buffer beforehand. */ 844 845 /** 846 * int jbd2_journal_get_create_access () - notify intent to use newly created bh 847 * @handle: transaction to new buffer to 848 * @bh: new buffer. 849 * 850 * Call this if you create a new bh. 851 */ 852 int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh) 853 { 854 transaction_t *transaction = handle->h_transaction; 855 journal_t *journal = transaction->t_journal; 856 struct journal_head *jh = jbd2_journal_add_journal_head(bh); 857 int err; 858 859 jbd_debug(5, "journal_head %p\n", jh); 860 err = -EROFS; 861 if (is_handle_aborted(handle)) 862 goto out; 863 err = 0; 864 865 JBUFFER_TRACE(jh, "entry"); 866 /* 867 * The buffer may already belong to this transaction due to pre-zeroing 868 * in the filesystem's new_block code. It may also be on the previous, 869 * committing transaction's lists, but it HAS to be in Forget state in 870 * that case: the transaction must have deleted the buffer for it to be 871 * reused here. 872 */ 873 jbd_lock_bh_state(bh); 874 spin_lock(&journal->j_list_lock); 875 J_ASSERT_JH(jh, (jh->b_transaction == transaction || 876 jh->b_transaction == NULL || 877 (jh->b_transaction == journal->j_committing_transaction && 878 jh->b_jlist == BJ_Forget))); 879 880 J_ASSERT_JH(jh, jh->b_next_transaction == NULL); 881 J_ASSERT_JH(jh, buffer_locked(jh2bh(jh))); 882 883 if (jh->b_transaction == NULL) { 884 /* 885 * Previous jbd2_journal_forget() could have left the buffer 886 * with jbddirty bit set because it was being committed. When 887 * the commit finished, we've filed the buffer for 888 * checkpointing and marked it dirty. Now we are reallocating 889 * the buffer so the transaction freeing it must have 890 * committed and so it's safe to clear the dirty bit. 891 */ 892 clear_buffer_dirty(jh2bh(jh)); 893 jh->b_transaction = transaction; 894 895 /* first access by this transaction */ 896 jh->b_modified = 0; 897 898 JBUFFER_TRACE(jh, "file as BJ_Reserved"); 899 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved); 900 } else if (jh->b_transaction == journal->j_committing_transaction) { 901 /* first access by this transaction */ 902 jh->b_modified = 0; 903 904 JBUFFER_TRACE(jh, "set next transaction"); 905 jh->b_next_transaction = transaction; 906 } 907 spin_unlock(&journal->j_list_lock); 908 jbd_unlock_bh_state(bh); 909 910 /* 911 * akpm: I added this. ext3_alloc_branch can pick up new indirect 912 * blocks which contain freed but then revoked metadata. We need 913 * to cancel the revoke in case we end up freeing it yet again 914 * and the reallocating as data - this would cause a second revoke, 915 * which hits an assertion error. 916 */ 917 JBUFFER_TRACE(jh, "cancelling revoke"); 918 jbd2_journal_cancel_revoke(handle, jh); 919 jbd2_journal_put_journal_head(jh); 920 out: 921 return err; 922 } 923 924 /** 925 * int jbd2_journal_get_undo_access() - Notify intent to modify metadata with 926 * non-rewindable consequences 927 * @handle: transaction 928 * @bh: buffer to undo 929 * @credits: store the number of taken credits here (if not NULL) 930 * 931 * Sometimes there is a need to distinguish between metadata which has 932 * been committed to disk and that which has not. The ext3fs code uses 933 * this for freeing and allocating space, we have to make sure that we 934 * do not reuse freed space until the deallocation has been committed, 935 * since if we overwrote that space we would make the delete 936 * un-rewindable in case of a crash. 937 * 938 * To deal with that, jbd2_journal_get_undo_access requests write access to a 939 * buffer for parts of non-rewindable operations such as delete 940 * operations on the bitmaps. The journaling code must keep a copy of 941 * the buffer's contents prior to the undo_access call until such time 942 * as we know that the buffer has definitely been committed to disk. 943 * 944 * We never need to know which transaction the committed data is part 945 * of, buffers touched here are guaranteed to be dirtied later and so 946 * will be committed to a new transaction in due course, at which point 947 * we can discard the old committed data pointer. 948 * 949 * Returns error number or 0 on success. 950 */ 951 int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh) 952 { 953 int err; 954 struct journal_head *jh = jbd2_journal_add_journal_head(bh); 955 char *committed_data = NULL; 956 957 JBUFFER_TRACE(jh, "entry"); 958 959 /* 960 * Do this first --- it can drop the journal lock, so we want to 961 * make sure that obtaining the committed_data is done 962 * atomically wrt. completion of any outstanding commits. 963 */ 964 err = do_get_write_access(handle, jh, 1); 965 if (err) 966 goto out; 967 968 repeat: 969 if (!jh->b_committed_data) { 970 committed_data = jbd2_alloc(jh2bh(jh)->b_size, GFP_NOFS); 971 if (!committed_data) { 972 printk(KERN_EMERG "%s: No memory for committed data\n", 973 __func__); 974 err = -ENOMEM; 975 goto out; 976 } 977 } 978 979 jbd_lock_bh_state(bh); 980 if (!jh->b_committed_data) { 981 /* Copy out the current buffer contents into the 982 * preserved, committed copy. */ 983 JBUFFER_TRACE(jh, "generate b_committed data"); 984 if (!committed_data) { 985 jbd_unlock_bh_state(bh); 986 goto repeat; 987 } 988 989 jh->b_committed_data = committed_data; 990 committed_data = NULL; 991 memcpy(jh->b_committed_data, bh->b_data, bh->b_size); 992 } 993 jbd_unlock_bh_state(bh); 994 out: 995 jbd2_journal_put_journal_head(jh); 996 if (unlikely(committed_data)) 997 jbd2_free(committed_data, bh->b_size); 998 return err; 999 } 1000 1001 /** 1002 * void jbd2_journal_set_triggers() - Add triggers for commit writeout 1003 * @bh: buffer to trigger on 1004 * @type: struct jbd2_buffer_trigger_type containing the trigger(s). 1005 * 1006 * Set any triggers on this journal_head. This is always safe, because 1007 * triggers for a committing buffer will be saved off, and triggers for 1008 * a running transaction will match the buffer in that transaction. 1009 * 1010 * Call with NULL to clear the triggers. 1011 */ 1012 void jbd2_journal_set_triggers(struct buffer_head *bh, 1013 struct jbd2_buffer_trigger_type *type) 1014 { 1015 struct journal_head *jh = bh2jh(bh); 1016 1017 jh->b_triggers = type; 1018 } 1019 1020 void jbd2_buffer_frozen_trigger(struct journal_head *jh, void *mapped_data, 1021 struct jbd2_buffer_trigger_type *triggers) 1022 { 1023 struct buffer_head *bh = jh2bh(jh); 1024 1025 if (!triggers || !triggers->t_frozen) 1026 return; 1027 1028 triggers->t_frozen(triggers, bh, mapped_data, bh->b_size); 1029 } 1030 1031 void jbd2_buffer_abort_trigger(struct journal_head *jh, 1032 struct jbd2_buffer_trigger_type *triggers) 1033 { 1034 if (!triggers || !triggers->t_abort) 1035 return; 1036 1037 triggers->t_abort(triggers, jh2bh(jh)); 1038 } 1039 1040 1041 1042 /** 1043 * int jbd2_journal_dirty_metadata() - mark a buffer as containing dirty metadata 1044 * @handle: transaction to add buffer to. 1045 * @bh: buffer to mark 1046 * 1047 * mark dirty metadata which needs to be journaled as part of the current 1048 * transaction. 1049 * 1050 * The buffer is placed on the transaction's metadata list and is marked 1051 * as belonging to the transaction. 1052 * 1053 * Returns error number or 0 on success. 1054 * 1055 * Special care needs to be taken if the buffer already belongs to the 1056 * current committing transaction (in which case we should have frozen 1057 * data present for that commit). In that case, we don't relink the 1058 * buffer: that only gets done when the old transaction finally 1059 * completes its commit. 1060 */ 1061 int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh) 1062 { 1063 transaction_t *transaction = handle->h_transaction; 1064 journal_t *journal = transaction->t_journal; 1065 struct journal_head *jh = bh2jh(bh); 1066 1067 jbd_debug(5, "journal_head %p\n", jh); 1068 JBUFFER_TRACE(jh, "entry"); 1069 if (is_handle_aborted(handle)) 1070 goto out; 1071 1072 jbd_lock_bh_state(bh); 1073 1074 if (jh->b_modified == 0) { 1075 /* 1076 * This buffer's got modified and becoming part 1077 * of the transaction. This needs to be done 1078 * once a transaction -bzzz 1079 */ 1080 jh->b_modified = 1; 1081 J_ASSERT_JH(jh, handle->h_buffer_credits > 0); 1082 handle->h_buffer_credits--; 1083 } 1084 1085 /* 1086 * fastpath, to avoid expensive locking. If this buffer is already 1087 * on the running transaction's metadata list there is nothing to do. 1088 * Nobody can take it off again because there is a handle open. 1089 * I _think_ we're OK here with SMP barriers - a mistaken decision will 1090 * result in this test being false, so we go in and take the locks. 1091 */ 1092 if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) { 1093 JBUFFER_TRACE(jh, "fastpath"); 1094 J_ASSERT_JH(jh, jh->b_transaction == 1095 journal->j_running_transaction); 1096 goto out_unlock_bh; 1097 } 1098 1099 set_buffer_jbddirty(bh); 1100 1101 /* 1102 * Metadata already on the current transaction list doesn't 1103 * need to be filed. Metadata on another transaction's list must 1104 * be committing, and will be refiled once the commit completes: 1105 * leave it alone for now. 1106 */ 1107 if (jh->b_transaction != transaction) { 1108 JBUFFER_TRACE(jh, "already on other transaction"); 1109 J_ASSERT_JH(jh, jh->b_transaction == 1110 journal->j_committing_transaction); 1111 J_ASSERT_JH(jh, jh->b_next_transaction == transaction); 1112 /* And this case is illegal: we can't reuse another 1113 * transaction's data buffer, ever. */ 1114 goto out_unlock_bh; 1115 } 1116 1117 /* That test should have eliminated the following case: */ 1118 J_ASSERT_JH(jh, jh->b_frozen_data == NULL); 1119 1120 JBUFFER_TRACE(jh, "file as BJ_Metadata"); 1121 spin_lock(&journal->j_list_lock); 1122 __jbd2_journal_file_buffer(jh, handle->h_transaction, BJ_Metadata); 1123 spin_unlock(&journal->j_list_lock); 1124 out_unlock_bh: 1125 jbd_unlock_bh_state(bh); 1126 out: 1127 JBUFFER_TRACE(jh, "exit"); 1128 return 0; 1129 } 1130 1131 /* 1132 * jbd2_journal_release_buffer: undo a get_write_access without any buffer 1133 * updates, if the update decided in the end that it didn't need access. 1134 * 1135 */ 1136 void 1137 jbd2_journal_release_buffer(handle_t *handle, struct buffer_head *bh) 1138 { 1139 BUFFER_TRACE(bh, "entry"); 1140 } 1141 1142 /** 1143 * void jbd2_journal_forget() - bforget() for potentially-journaled buffers. 1144 * @handle: transaction handle 1145 * @bh: bh to 'forget' 1146 * 1147 * We can only do the bforget if there are no commits pending against the 1148 * buffer. If the buffer is dirty in the current running transaction we 1149 * can safely unlink it. 1150 * 1151 * bh may not be a journalled buffer at all - it may be a non-JBD 1152 * buffer which came off the hashtable. Check for this. 1153 * 1154 * Decrements bh->b_count by one. 1155 * 1156 * Allow this call even if the handle has aborted --- it may be part of 1157 * the caller's cleanup after an abort. 1158 */ 1159 int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh) 1160 { 1161 transaction_t *transaction = handle->h_transaction; 1162 journal_t *journal = transaction->t_journal; 1163 struct journal_head *jh; 1164 int drop_reserve = 0; 1165 int err = 0; 1166 int was_modified = 0; 1167 1168 BUFFER_TRACE(bh, "entry"); 1169 1170 jbd_lock_bh_state(bh); 1171 spin_lock(&journal->j_list_lock); 1172 1173 if (!buffer_jbd(bh)) 1174 goto not_jbd; 1175 jh = bh2jh(bh); 1176 1177 /* Critical error: attempting to delete a bitmap buffer, maybe? 1178 * Don't do any jbd operations, and return an error. */ 1179 if (!J_EXPECT_JH(jh, !jh->b_committed_data, 1180 "inconsistent data on disk")) { 1181 err = -EIO; 1182 goto not_jbd; 1183 } 1184 1185 /* keep track of wether or not this transaction modified us */ 1186 was_modified = jh->b_modified; 1187 1188 /* 1189 * The buffer's going from the transaction, we must drop 1190 * all references -bzzz 1191 */ 1192 jh->b_modified = 0; 1193 1194 if (jh->b_transaction == handle->h_transaction) { 1195 J_ASSERT_JH(jh, !jh->b_frozen_data); 1196 1197 /* If we are forgetting a buffer which is already part 1198 * of this transaction, then we can just drop it from 1199 * the transaction immediately. */ 1200 clear_buffer_dirty(bh); 1201 clear_buffer_jbddirty(bh); 1202 1203 JBUFFER_TRACE(jh, "belongs to current transaction: unfile"); 1204 1205 /* 1206 * we only want to drop a reference if this transaction 1207 * modified the buffer 1208 */ 1209 if (was_modified) 1210 drop_reserve = 1; 1211 1212 /* 1213 * We are no longer going to journal this buffer. 1214 * However, the commit of this transaction is still 1215 * important to the buffer: the delete that we are now 1216 * processing might obsolete an old log entry, so by 1217 * committing, we can satisfy the buffer's checkpoint. 1218 * 1219 * So, if we have a checkpoint on the buffer, we should 1220 * now refile the buffer on our BJ_Forget list so that 1221 * we know to remove the checkpoint after we commit. 1222 */ 1223 1224 if (jh->b_cp_transaction) { 1225 __jbd2_journal_temp_unlink_buffer(jh); 1226 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget); 1227 } else { 1228 __jbd2_journal_unfile_buffer(jh); 1229 jbd2_journal_remove_journal_head(bh); 1230 __brelse(bh); 1231 if (!buffer_jbd(bh)) { 1232 spin_unlock(&journal->j_list_lock); 1233 jbd_unlock_bh_state(bh); 1234 __bforget(bh); 1235 goto drop; 1236 } 1237 } 1238 } else if (jh->b_transaction) { 1239 J_ASSERT_JH(jh, (jh->b_transaction == 1240 journal->j_committing_transaction)); 1241 /* However, if the buffer is still owned by a prior 1242 * (committing) transaction, we can't drop it yet... */ 1243 JBUFFER_TRACE(jh, "belongs to older transaction"); 1244 /* ... but we CAN drop it from the new transaction if we 1245 * have also modified it since the original commit. */ 1246 1247 if (jh->b_next_transaction) { 1248 J_ASSERT(jh->b_next_transaction == transaction); 1249 jh->b_next_transaction = NULL; 1250 1251 /* 1252 * only drop a reference if this transaction modified 1253 * the buffer 1254 */ 1255 if (was_modified) 1256 drop_reserve = 1; 1257 } 1258 } 1259 1260 not_jbd: 1261 spin_unlock(&journal->j_list_lock); 1262 jbd_unlock_bh_state(bh); 1263 __brelse(bh); 1264 drop: 1265 if (drop_reserve) { 1266 /* no need to reserve log space for this block -bzzz */ 1267 handle->h_buffer_credits++; 1268 } 1269 return err; 1270 } 1271 1272 /** 1273 * int jbd2_journal_stop() - complete a transaction 1274 * @handle: tranaction to complete. 1275 * 1276 * All done for a particular handle. 1277 * 1278 * There is not much action needed here. We just return any remaining 1279 * buffer credits to the transaction and remove the handle. The only 1280 * complication is that we need to start a commit operation if the 1281 * filesystem is marked for synchronous update. 1282 * 1283 * jbd2_journal_stop itself will not usually return an error, but it may 1284 * do so in unusual circumstances. In particular, expect it to 1285 * return -EIO if a jbd2_journal_abort has been executed since the 1286 * transaction began. 1287 */ 1288 int jbd2_journal_stop(handle_t *handle) 1289 { 1290 transaction_t *transaction = handle->h_transaction; 1291 journal_t *journal = transaction->t_journal; 1292 int err, wait_for_commit = 0; 1293 tid_t tid; 1294 pid_t pid; 1295 1296 J_ASSERT(journal_current_handle() == handle); 1297 1298 if (is_handle_aborted(handle)) 1299 err = -EIO; 1300 else { 1301 J_ASSERT(atomic_read(&transaction->t_updates) > 0); 1302 err = 0; 1303 } 1304 1305 if (--handle->h_ref > 0) { 1306 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1, 1307 handle->h_ref); 1308 return err; 1309 } 1310 1311 jbd_debug(4, "Handle %p going down\n", handle); 1312 1313 /* 1314 * Implement synchronous transaction batching. If the handle 1315 * was synchronous, don't force a commit immediately. Let's 1316 * yield and let another thread piggyback onto this 1317 * transaction. Keep doing that while new threads continue to 1318 * arrive. It doesn't cost much - we're about to run a commit 1319 * and sleep on IO anyway. Speeds up many-threaded, many-dir 1320 * operations by 30x or more... 1321 * 1322 * We try and optimize the sleep time against what the 1323 * underlying disk can do, instead of having a static sleep 1324 * time. This is useful for the case where our storage is so 1325 * fast that it is more optimal to go ahead and force a flush 1326 * and wait for the transaction to be committed than it is to 1327 * wait for an arbitrary amount of time for new writers to 1328 * join the transaction. We achieve this by measuring how 1329 * long it takes to commit a transaction, and compare it with 1330 * how long this transaction has been running, and if run time 1331 * < commit time then we sleep for the delta and commit. This 1332 * greatly helps super fast disks that would see slowdowns as 1333 * more threads started doing fsyncs. 1334 * 1335 * But don't do this if this process was the most recent one 1336 * to perform a synchronous write. We do this to detect the 1337 * case where a single process is doing a stream of sync 1338 * writes. No point in waiting for joiners in that case. 1339 */ 1340 pid = current->pid; 1341 if (handle->h_sync && journal->j_last_sync_writer != pid) { 1342 u64 commit_time, trans_time; 1343 1344 journal->j_last_sync_writer = pid; 1345 1346 read_lock(&journal->j_state_lock); 1347 commit_time = journal->j_average_commit_time; 1348 read_unlock(&journal->j_state_lock); 1349 1350 trans_time = ktime_to_ns(ktime_sub(ktime_get(), 1351 transaction->t_start_time)); 1352 1353 commit_time = max_t(u64, commit_time, 1354 1000*journal->j_min_batch_time); 1355 commit_time = min_t(u64, commit_time, 1356 1000*journal->j_max_batch_time); 1357 1358 if (trans_time < commit_time) { 1359 ktime_t expires = ktime_add_ns(ktime_get(), 1360 commit_time); 1361 set_current_state(TASK_UNINTERRUPTIBLE); 1362 schedule_hrtimeout(&expires, HRTIMER_MODE_ABS); 1363 } 1364 } 1365 1366 if (handle->h_sync) 1367 transaction->t_synchronous_commit = 1; 1368 current->journal_info = NULL; 1369 atomic_sub(handle->h_buffer_credits, 1370 &transaction->t_outstanding_credits); 1371 1372 /* 1373 * If the handle is marked SYNC, we need to set another commit 1374 * going! We also want to force a commit if the current 1375 * transaction is occupying too much of the log, or if the 1376 * transaction is too old now. 1377 */ 1378 if (handle->h_sync || 1379 (atomic_read(&transaction->t_outstanding_credits) > 1380 journal->j_max_transaction_buffers) || 1381 time_after_eq(jiffies, transaction->t_expires)) { 1382 /* Do this even for aborted journals: an abort still 1383 * completes the commit thread, it just doesn't write 1384 * anything to disk. */ 1385 1386 jbd_debug(2, "transaction too old, requesting commit for " 1387 "handle %p\n", handle); 1388 /* This is non-blocking */ 1389 jbd2_log_start_commit(journal, transaction->t_tid); 1390 1391 /* 1392 * Special case: JBD2_SYNC synchronous updates require us 1393 * to wait for the commit to complete. 1394 */ 1395 if (handle->h_sync && !(current->flags & PF_MEMALLOC)) 1396 wait_for_commit = 1; 1397 } 1398 1399 /* 1400 * Once we drop t_updates, if it goes to zero the transaction 1401 * could start commiting on us and eventually disappear. So 1402 * once we do this, we must not dereference transaction 1403 * pointer again. 1404 */ 1405 tid = transaction->t_tid; 1406 if (atomic_dec_and_test(&transaction->t_updates)) { 1407 wake_up(&journal->j_wait_updates); 1408 if (journal->j_barrier_count) 1409 wake_up(&journal->j_wait_transaction_locked); 1410 } 1411 1412 if (wait_for_commit) 1413 err = jbd2_log_wait_commit(journal, tid); 1414 1415 lock_map_release(&handle->h_lockdep_map); 1416 1417 jbd2_free_handle(handle); 1418 return err; 1419 } 1420 1421 /** 1422 * int jbd2_journal_force_commit() - force any uncommitted transactions 1423 * @journal: journal to force 1424 * 1425 * For synchronous operations: force any uncommitted transactions 1426 * to disk. May seem kludgy, but it reuses all the handle batching 1427 * code in a very simple manner. 1428 */ 1429 int jbd2_journal_force_commit(journal_t *journal) 1430 { 1431 handle_t *handle; 1432 int ret; 1433 1434 handle = jbd2_journal_start(journal, 1); 1435 if (IS_ERR(handle)) { 1436 ret = PTR_ERR(handle); 1437 } else { 1438 handle->h_sync = 1; 1439 ret = jbd2_journal_stop(handle); 1440 } 1441 return ret; 1442 } 1443 1444 /* 1445 * 1446 * List management code snippets: various functions for manipulating the 1447 * transaction buffer lists. 1448 * 1449 */ 1450 1451 /* 1452 * Append a buffer to a transaction list, given the transaction's list head 1453 * pointer. 1454 * 1455 * j_list_lock is held. 1456 * 1457 * jbd_lock_bh_state(jh2bh(jh)) is held. 1458 */ 1459 1460 static inline void 1461 __blist_add_buffer(struct journal_head **list, struct journal_head *jh) 1462 { 1463 if (!*list) { 1464 jh->b_tnext = jh->b_tprev = jh; 1465 *list = jh; 1466 } else { 1467 /* Insert at the tail of the list to preserve order */ 1468 struct journal_head *first = *list, *last = first->b_tprev; 1469 jh->b_tprev = last; 1470 jh->b_tnext = first; 1471 last->b_tnext = first->b_tprev = jh; 1472 } 1473 } 1474 1475 /* 1476 * Remove a buffer from a transaction list, given the transaction's list 1477 * head pointer. 1478 * 1479 * Called with j_list_lock held, and the journal may not be locked. 1480 * 1481 * jbd_lock_bh_state(jh2bh(jh)) is held. 1482 */ 1483 1484 static inline void 1485 __blist_del_buffer(struct journal_head **list, struct journal_head *jh) 1486 { 1487 if (*list == jh) { 1488 *list = jh->b_tnext; 1489 if (*list == jh) 1490 *list = NULL; 1491 } 1492 jh->b_tprev->b_tnext = jh->b_tnext; 1493 jh->b_tnext->b_tprev = jh->b_tprev; 1494 } 1495 1496 /* 1497 * Remove a buffer from the appropriate transaction list. 1498 * 1499 * Note that this function can *change* the value of 1500 * bh->b_transaction->t_buffers, t_forget, t_iobuf_list, t_shadow_list, 1501 * t_log_list or t_reserved_list. If the caller is holding onto a copy of one 1502 * of these pointers, it could go bad. Generally the caller needs to re-read 1503 * the pointer from the transaction_t. 1504 * 1505 * Called under j_list_lock. The journal may not be locked. 1506 */ 1507 void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh) 1508 { 1509 struct journal_head **list = NULL; 1510 transaction_t *transaction; 1511 struct buffer_head *bh = jh2bh(jh); 1512 1513 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); 1514 transaction = jh->b_transaction; 1515 if (transaction) 1516 assert_spin_locked(&transaction->t_journal->j_list_lock); 1517 1518 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types); 1519 if (jh->b_jlist != BJ_None) 1520 J_ASSERT_JH(jh, transaction != NULL); 1521 1522 switch (jh->b_jlist) { 1523 case BJ_None: 1524 return; 1525 case BJ_Metadata: 1526 transaction->t_nr_buffers--; 1527 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0); 1528 list = &transaction->t_buffers; 1529 break; 1530 case BJ_Forget: 1531 list = &transaction->t_forget; 1532 break; 1533 case BJ_IO: 1534 list = &transaction->t_iobuf_list; 1535 break; 1536 case BJ_Shadow: 1537 list = &transaction->t_shadow_list; 1538 break; 1539 case BJ_LogCtl: 1540 list = &transaction->t_log_list; 1541 break; 1542 case BJ_Reserved: 1543 list = &transaction->t_reserved_list; 1544 break; 1545 } 1546 1547 __blist_del_buffer(list, jh); 1548 jh->b_jlist = BJ_None; 1549 if (test_clear_buffer_jbddirty(bh)) 1550 mark_buffer_dirty(bh); /* Expose it to the VM */ 1551 } 1552 1553 void __jbd2_journal_unfile_buffer(struct journal_head *jh) 1554 { 1555 __jbd2_journal_temp_unlink_buffer(jh); 1556 jh->b_transaction = NULL; 1557 } 1558 1559 void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh) 1560 { 1561 jbd_lock_bh_state(jh2bh(jh)); 1562 spin_lock(&journal->j_list_lock); 1563 __jbd2_journal_unfile_buffer(jh); 1564 spin_unlock(&journal->j_list_lock); 1565 jbd_unlock_bh_state(jh2bh(jh)); 1566 } 1567 1568 /* 1569 * Called from jbd2_journal_try_to_free_buffers(). 1570 * 1571 * Called under jbd_lock_bh_state(bh) 1572 */ 1573 static void 1574 __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh) 1575 { 1576 struct journal_head *jh; 1577 1578 jh = bh2jh(bh); 1579 1580 if (buffer_locked(bh) || buffer_dirty(bh)) 1581 goto out; 1582 1583 if (jh->b_next_transaction != NULL) 1584 goto out; 1585 1586 spin_lock(&journal->j_list_lock); 1587 if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) { 1588 /* written-back checkpointed metadata buffer */ 1589 if (jh->b_jlist == BJ_None) { 1590 JBUFFER_TRACE(jh, "remove from checkpoint list"); 1591 __jbd2_journal_remove_checkpoint(jh); 1592 jbd2_journal_remove_journal_head(bh); 1593 __brelse(bh); 1594 } 1595 } 1596 spin_unlock(&journal->j_list_lock); 1597 out: 1598 return; 1599 } 1600 1601 /** 1602 * int jbd2_journal_try_to_free_buffers() - try to free page buffers. 1603 * @journal: journal for operation 1604 * @page: to try and free 1605 * @gfp_mask: we use the mask to detect how hard should we try to release 1606 * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to 1607 * release the buffers. 1608 * 1609 * 1610 * For all the buffers on this page, 1611 * if they are fully written out ordered data, move them onto BUF_CLEAN 1612 * so try_to_free_buffers() can reap them. 1613 * 1614 * This function returns non-zero if we wish try_to_free_buffers() 1615 * to be called. We do this if the page is releasable by try_to_free_buffers(). 1616 * We also do it if the page has locked or dirty buffers and the caller wants 1617 * us to perform sync or async writeout. 1618 * 1619 * This complicates JBD locking somewhat. We aren't protected by the 1620 * BKL here. We wish to remove the buffer from its committing or 1621 * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer. 1622 * 1623 * This may *change* the value of transaction_t->t_datalist, so anyone 1624 * who looks at t_datalist needs to lock against this function. 1625 * 1626 * Even worse, someone may be doing a jbd2_journal_dirty_data on this 1627 * buffer. So we need to lock against that. jbd2_journal_dirty_data() 1628 * will come out of the lock with the buffer dirty, which makes it 1629 * ineligible for release here. 1630 * 1631 * Who else is affected by this? hmm... Really the only contender 1632 * is do_get_write_access() - it could be looking at the buffer while 1633 * journal_try_to_free_buffer() is changing its state. But that 1634 * cannot happen because we never reallocate freed data as metadata 1635 * while the data is part of a transaction. Yes? 1636 * 1637 * Return 0 on failure, 1 on success 1638 */ 1639 int jbd2_journal_try_to_free_buffers(journal_t *journal, 1640 struct page *page, gfp_t gfp_mask) 1641 { 1642 struct buffer_head *head; 1643 struct buffer_head *bh; 1644 int ret = 0; 1645 1646 J_ASSERT(PageLocked(page)); 1647 1648 head = page_buffers(page); 1649 bh = head; 1650 do { 1651 struct journal_head *jh; 1652 1653 /* 1654 * We take our own ref against the journal_head here to avoid 1655 * having to add tons of locking around each instance of 1656 * jbd2_journal_remove_journal_head() and 1657 * jbd2_journal_put_journal_head(). 1658 */ 1659 jh = jbd2_journal_grab_journal_head(bh); 1660 if (!jh) 1661 continue; 1662 1663 jbd_lock_bh_state(bh); 1664 __journal_try_to_free_buffer(journal, bh); 1665 jbd2_journal_put_journal_head(jh); 1666 jbd_unlock_bh_state(bh); 1667 if (buffer_jbd(bh)) 1668 goto busy; 1669 } while ((bh = bh->b_this_page) != head); 1670 1671 ret = try_to_free_buffers(page); 1672 1673 busy: 1674 return ret; 1675 } 1676 1677 /* 1678 * This buffer is no longer needed. If it is on an older transaction's 1679 * checkpoint list we need to record it on this transaction's forget list 1680 * to pin this buffer (and hence its checkpointing transaction) down until 1681 * this transaction commits. If the buffer isn't on a checkpoint list, we 1682 * release it. 1683 * Returns non-zero if JBD no longer has an interest in the buffer. 1684 * 1685 * Called under j_list_lock. 1686 * 1687 * Called under jbd_lock_bh_state(bh). 1688 */ 1689 static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction) 1690 { 1691 int may_free = 1; 1692 struct buffer_head *bh = jh2bh(jh); 1693 1694 __jbd2_journal_unfile_buffer(jh); 1695 1696 if (jh->b_cp_transaction) { 1697 JBUFFER_TRACE(jh, "on running+cp transaction"); 1698 /* 1699 * We don't want to write the buffer anymore, clear the 1700 * bit so that we don't confuse checks in 1701 * __journal_file_buffer 1702 */ 1703 clear_buffer_dirty(bh); 1704 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget); 1705 may_free = 0; 1706 } else { 1707 JBUFFER_TRACE(jh, "on running transaction"); 1708 jbd2_journal_remove_journal_head(bh); 1709 __brelse(bh); 1710 } 1711 return may_free; 1712 } 1713 1714 /* 1715 * jbd2_journal_invalidatepage 1716 * 1717 * This code is tricky. It has a number of cases to deal with. 1718 * 1719 * There are two invariants which this code relies on: 1720 * 1721 * i_size must be updated on disk before we start calling invalidatepage on the 1722 * data. 1723 * 1724 * This is done in ext3 by defining an ext3_setattr method which 1725 * updates i_size before truncate gets going. By maintaining this 1726 * invariant, we can be sure that it is safe to throw away any buffers 1727 * attached to the current transaction: once the transaction commits, 1728 * we know that the data will not be needed. 1729 * 1730 * Note however that we can *not* throw away data belonging to the 1731 * previous, committing transaction! 1732 * 1733 * Any disk blocks which *are* part of the previous, committing 1734 * transaction (and which therefore cannot be discarded immediately) are 1735 * not going to be reused in the new running transaction 1736 * 1737 * The bitmap committed_data images guarantee this: any block which is 1738 * allocated in one transaction and removed in the next will be marked 1739 * as in-use in the committed_data bitmap, so cannot be reused until 1740 * the next transaction to delete the block commits. This means that 1741 * leaving committing buffers dirty is quite safe: the disk blocks 1742 * cannot be reallocated to a different file and so buffer aliasing is 1743 * not possible. 1744 * 1745 * 1746 * The above applies mainly to ordered data mode. In writeback mode we 1747 * don't make guarantees about the order in which data hits disk --- in 1748 * particular we don't guarantee that new dirty data is flushed before 1749 * transaction commit --- so it is always safe just to discard data 1750 * immediately in that mode. --sct 1751 */ 1752 1753 /* 1754 * The journal_unmap_buffer helper function returns zero if the buffer 1755 * concerned remains pinned as an anonymous buffer belonging to an older 1756 * transaction. 1757 * 1758 * We're outside-transaction here. Either or both of j_running_transaction 1759 * and j_committing_transaction may be NULL. 1760 */ 1761 static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh) 1762 { 1763 transaction_t *transaction; 1764 struct journal_head *jh; 1765 int may_free = 1; 1766 int ret; 1767 1768 BUFFER_TRACE(bh, "entry"); 1769 1770 /* 1771 * It is safe to proceed here without the j_list_lock because the 1772 * buffers cannot be stolen by try_to_free_buffers as long as we are 1773 * holding the page lock. --sct 1774 */ 1775 1776 if (!buffer_jbd(bh)) 1777 goto zap_buffer_unlocked; 1778 1779 /* OK, we have data buffer in journaled mode */ 1780 write_lock(&journal->j_state_lock); 1781 jbd_lock_bh_state(bh); 1782 spin_lock(&journal->j_list_lock); 1783 1784 jh = jbd2_journal_grab_journal_head(bh); 1785 if (!jh) 1786 goto zap_buffer_no_jh; 1787 1788 /* 1789 * We cannot remove the buffer from checkpoint lists until the 1790 * transaction adding inode to orphan list (let's call it T) 1791 * is committed. Otherwise if the transaction changing the 1792 * buffer would be cleaned from the journal before T is 1793 * committed, a crash will cause that the correct contents of 1794 * the buffer will be lost. On the other hand we have to 1795 * clear the buffer dirty bit at latest at the moment when the 1796 * transaction marking the buffer as freed in the filesystem 1797 * structures is committed because from that moment on the 1798 * buffer can be reallocated and used by a different page. 1799 * Since the block hasn't been freed yet but the inode has 1800 * already been added to orphan list, it is safe for us to add 1801 * the buffer to BJ_Forget list of the newest transaction. 1802 */ 1803 transaction = jh->b_transaction; 1804 if (transaction == NULL) { 1805 /* First case: not on any transaction. If it 1806 * has no checkpoint link, then we can zap it: 1807 * it's a writeback-mode buffer so we don't care 1808 * if it hits disk safely. */ 1809 if (!jh->b_cp_transaction) { 1810 JBUFFER_TRACE(jh, "not on any transaction: zap"); 1811 goto zap_buffer; 1812 } 1813 1814 if (!buffer_dirty(bh)) { 1815 /* bdflush has written it. We can drop it now */ 1816 goto zap_buffer; 1817 } 1818 1819 /* OK, it must be in the journal but still not 1820 * written fully to disk: it's metadata or 1821 * journaled data... */ 1822 1823 if (journal->j_running_transaction) { 1824 /* ... and once the current transaction has 1825 * committed, the buffer won't be needed any 1826 * longer. */ 1827 JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget"); 1828 ret = __dispose_buffer(jh, 1829 journal->j_running_transaction); 1830 jbd2_journal_put_journal_head(jh); 1831 spin_unlock(&journal->j_list_lock); 1832 jbd_unlock_bh_state(bh); 1833 write_unlock(&journal->j_state_lock); 1834 return ret; 1835 } else { 1836 /* There is no currently-running transaction. So the 1837 * orphan record which we wrote for this file must have 1838 * passed into commit. We must attach this buffer to 1839 * the committing transaction, if it exists. */ 1840 if (journal->j_committing_transaction) { 1841 JBUFFER_TRACE(jh, "give to committing trans"); 1842 ret = __dispose_buffer(jh, 1843 journal->j_committing_transaction); 1844 jbd2_journal_put_journal_head(jh); 1845 spin_unlock(&journal->j_list_lock); 1846 jbd_unlock_bh_state(bh); 1847 write_unlock(&journal->j_state_lock); 1848 return ret; 1849 } else { 1850 /* The orphan record's transaction has 1851 * committed. We can cleanse this buffer */ 1852 clear_buffer_jbddirty(bh); 1853 goto zap_buffer; 1854 } 1855 } 1856 } else if (transaction == journal->j_committing_transaction) { 1857 JBUFFER_TRACE(jh, "on committing transaction"); 1858 /* 1859 * The buffer is committing, we simply cannot touch 1860 * it. So we just set j_next_transaction to the 1861 * running transaction (if there is one) and mark 1862 * buffer as freed so that commit code knows it should 1863 * clear dirty bits when it is done with the buffer. 1864 */ 1865 set_buffer_freed(bh); 1866 if (journal->j_running_transaction && buffer_jbddirty(bh)) 1867 jh->b_next_transaction = journal->j_running_transaction; 1868 jbd2_journal_put_journal_head(jh); 1869 spin_unlock(&journal->j_list_lock); 1870 jbd_unlock_bh_state(bh); 1871 write_unlock(&journal->j_state_lock); 1872 return 0; 1873 } else { 1874 /* Good, the buffer belongs to the running transaction. 1875 * We are writing our own transaction's data, not any 1876 * previous one's, so it is safe to throw it away 1877 * (remember that we expect the filesystem to have set 1878 * i_size already for this truncate so recovery will not 1879 * expose the disk blocks we are discarding here.) */ 1880 J_ASSERT_JH(jh, transaction == journal->j_running_transaction); 1881 JBUFFER_TRACE(jh, "on running transaction"); 1882 may_free = __dispose_buffer(jh, transaction); 1883 } 1884 1885 zap_buffer: 1886 jbd2_journal_put_journal_head(jh); 1887 zap_buffer_no_jh: 1888 spin_unlock(&journal->j_list_lock); 1889 jbd_unlock_bh_state(bh); 1890 write_unlock(&journal->j_state_lock); 1891 zap_buffer_unlocked: 1892 clear_buffer_dirty(bh); 1893 J_ASSERT_BH(bh, !buffer_jbddirty(bh)); 1894 clear_buffer_mapped(bh); 1895 clear_buffer_req(bh); 1896 clear_buffer_new(bh); 1897 bh->b_bdev = NULL; 1898 return may_free; 1899 } 1900 1901 /** 1902 * void jbd2_journal_invalidatepage() 1903 * @journal: journal to use for flush... 1904 * @page: page to flush 1905 * @offset: length of page to invalidate. 1906 * 1907 * Reap page buffers containing data after offset in page. 1908 * 1909 */ 1910 void jbd2_journal_invalidatepage(journal_t *journal, 1911 struct page *page, 1912 unsigned long offset) 1913 { 1914 struct buffer_head *head, *bh, *next; 1915 unsigned int curr_off = 0; 1916 int may_free = 1; 1917 1918 if (!PageLocked(page)) 1919 BUG(); 1920 if (!page_has_buffers(page)) 1921 return; 1922 1923 /* We will potentially be playing with lists other than just the 1924 * data lists (especially for journaled data mode), so be 1925 * cautious in our locking. */ 1926 1927 head = bh = page_buffers(page); 1928 do { 1929 unsigned int next_off = curr_off + bh->b_size; 1930 next = bh->b_this_page; 1931 1932 if (offset <= curr_off) { 1933 /* This block is wholly outside the truncation point */ 1934 lock_buffer(bh); 1935 may_free &= journal_unmap_buffer(journal, bh); 1936 unlock_buffer(bh); 1937 } 1938 curr_off = next_off; 1939 bh = next; 1940 1941 } while (bh != head); 1942 1943 if (!offset) { 1944 if (may_free && try_to_free_buffers(page)) 1945 J_ASSERT(!page_has_buffers(page)); 1946 } 1947 } 1948 1949 /* 1950 * File a buffer on the given transaction list. 1951 */ 1952 void __jbd2_journal_file_buffer(struct journal_head *jh, 1953 transaction_t *transaction, int jlist) 1954 { 1955 struct journal_head **list = NULL; 1956 int was_dirty = 0; 1957 struct buffer_head *bh = jh2bh(jh); 1958 1959 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); 1960 assert_spin_locked(&transaction->t_journal->j_list_lock); 1961 1962 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types); 1963 J_ASSERT_JH(jh, jh->b_transaction == transaction || 1964 jh->b_transaction == NULL); 1965 1966 if (jh->b_transaction && jh->b_jlist == jlist) 1967 return; 1968 1969 if (jlist == BJ_Metadata || jlist == BJ_Reserved || 1970 jlist == BJ_Shadow || jlist == BJ_Forget) { 1971 /* 1972 * For metadata buffers, we track dirty bit in buffer_jbddirty 1973 * instead of buffer_dirty. We should not see a dirty bit set 1974 * here because we clear it in do_get_write_access but e.g. 1975 * tune2fs can modify the sb and set the dirty bit at any time 1976 * so we try to gracefully handle that. 1977 */ 1978 if (buffer_dirty(bh)) 1979 warn_dirty_buffer(bh); 1980 if (test_clear_buffer_dirty(bh) || 1981 test_clear_buffer_jbddirty(bh)) 1982 was_dirty = 1; 1983 } 1984 1985 if (jh->b_transaction) 1986 __jbd2_journal_temp_unlink_buffer(jh); 1987 jh->b_transaction = transaction; 1988 1989 switch (jlist) { 1990 case BJ_None: 1991 J_ASSERT_JH(jh, !jh->b_committed_data); 1992 J_ASSERT_JH(jh, !jh->b_frozen_data); 1993 return; 1994 case BJ_Metadata: 1995 transaction->t_nr_buffers++; 1996 list = &transaction->t_buffers; 1997 break; 1998 case BJ_Forget: 1999 list = &transaction->t_forget; 2000 break; 2001 case BJ_IO: 2002 list = &transaction->t_iobuf_list; 2003 break; 2004 case BJ_Shadow: 2005 list = &transaction->t_shadow_list; 2006 break; 2007 case BJ_LogCtl: 2008 list = &transaction->t_log_list; 2009 break; 2010 case BJ_Reserved: 2011 list = &transaction->t_reserved_list; 2012 break; 2013 } 2014 2015 __blist_add_buffer(list, jh); 2016 jh->b_jlist = jlist; 2017 2018 if (was_dirty) 2019 set_buffer_jbddirty(bh); 2020 } 2021 2022 void jbd2_journal_file_buffer(struct journal_head *jh, 2023 transaction_t *transaction, int jlist) 2024 { 2025 jbd_lock_bh_state(jh2bh(jh)); 2026 spin_lock(&transaction->t_journal->j_list_lock); 2027 __jbd2_journal_file_buffer(jh, transaction, jlist); 2028 spin_unlock(&transaction->t_journal->j_list_lock); 2029 jbd_unlock_bh_state(jh2bh(jh)); 2030 } 2031 2032 /* 2033 * Remove a buffer from its current buffer list in preparation for 2034 * dropping it from its current transaction entirely. If the buffer has 2035 * already started to be used by a subsequent transaction, refile the 2036 * buffer on that transaction's metadata list. 2037 * 2038 * Called under journal->j_list_lock 2039 * 2040 * Called under jbd_lock_bh_state(jh2bh(jh)) 2041 */ 2042 void __jbd2_journal_refile_buffer(struct journal_head *jh) 2043 { 2044 int was_dirty, jlist; 2045 struct buffer_head *bh = jh2bh(jh); 2046 2047 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); 2048 if (jh->b_transaction) 2049 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock); 2050 2051 /* If the buffer is now unused, just drop it. */ 2052 if (jh->b_next_transaction == NULL) { 2053 __jbd2_journal_unfile_buffer(jh); 2054 return; 2055 } 2056 2057 /* 2058 * It has been modified by a later transaction: add it to the new 2059 * transaction's metadata list. 2060 */ 2061 2062 was_dirty = test_clear_buffer_jbddirty(bh); 2063 __jbd2_journal_temp_unlink_buffer(jh); 2064 jh->b_transaction = jh->b_next_transaction; 2065 jh->b_next_transaction = NULL; 2066 if (buffer_freed(bh)) 2067 jlist = BJ_Forget; 2068 else if (jh->b_modified) 2069 jlist = BJ_Metadata; 2070 else 2071 jlist = BJ_Reserved; 2072 __jbd2_journal_file_buffer(jh, jh->b_transaction, jlist); 2073 J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING); 2074 2075 if (was_dirty) 2076 set_buffer_jbddirty(bh); 2077 } 2078 2079 /* 2080 * For the unlocked version of this call, also make sure that any 2081 * hanging journal_head is cleaned up if necessary. 2082 * 2083 * __jbd2_journal_refile_buffer is usually called as part of a single locked 2084 * operation on a buffer_head, in which the caller is probably going to 2085 * be hooking the journal_head onto other lists. In that case it is up 2086 * to the caller to remove the journal_head if necessary. For the 2087 * unlocked jbd2_journal_refile_buffer call, the caller isn't going to be 2088 * doing anything else to the buffer so we need to do the cleanup 2089 * ourselves to avoid a jh leak. 2090 * 2091 * *** The journal_head may be freed by this call! *** 2092 */ 2093 void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh) 2094 { 2095 struct buffer_head *bh = jh2bh(jh); 2096 2097 jbd_lock_bh_state(bh); 2098 spin_lock(&journal->j_list_lock); 2099 2100 __jbd2_journal_refile_buffer(jh); 2101 jbd_unlock_bh_state(bh); 2102 jbd2_journal_remove_journal_head(bh); 2103 2104 spin_unlock(&journal->j_list_lock); 2105 __brelse(bh); 2106 } 2107 2108 /* 2109 * File inode in the inode list of the handle's transaction 2110 */ 2111 int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode) 2112 { 2113 transaction_t *transaction = handle->h_transaction; 2114 journal_t *journal = transaction->t_journal; 2115 2116 if (is_handle_aborted(handle)) 2117 return -EIO; 2118 2119 jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode->i_vfs_inode->i_ino, 2120 transaction->t_tid); 2121 2122 /* 2123 * First check whether inode isn't already on the transaction's 2124 * lists without taking the lock. Note that this check is safe 2125 * without the lock as we cannot race with somebody removing inode 2126 * from the transaction. The reason is that we remove inode from the 2127 * transaction only in journal_release_jbd_inode() and when we commit 2128 * the transaction. We are guarded from the first case by holding 2129 * a reference to the inode. We are safe against the second case 2130 * because if jinode->i_transaction == transaction, commit code 2131 * cannot touch the transaction because we hold reference to it, 2132 * and if jinode->i_next_transaction == transaction, commit code 2133 * will only file the inode where we want it. 2134 */ 2135 if (jinode->i_transaction == transaction || 2136 jinode->i_next_transaction == transaction) 2137 return 0; 2138 2139 spin_lock(&journal->j_list_lock); 2140 2141 if (jinode->i_transaction == transaction || 2142 jinode->i_next_transaction == transaction) 2143 goto done; 2144 2145 /* On some different transaction's list - should be 2146 * the committing one */ 2147 if (jinode->i_transaction) { 2148 J_ASSERT(jinode->i_next_transaction == NULL); 2149 J_ASSERT(jinode->i_transaction == 2150 journal->j_committing_transaction); 2151 jinode->i_next_transaction = transaction; 2152 goto done; 2153 } 2154 /* Not on any transaction list... */ 2155 J_ASSERT(!jinode->i_next_transaction); 2156 jinode->i_transaction = transaction; 2157 list_add(&jinode->i_list, &transaction->t_inode_list); 2158 done: 2159 spin_unlock(&journal->j_list_lock); 2160 2161 return 0; 2162 } 2163 2164 /* 2165 * File truncate and transaction commit interact with each other in a 2166 * non-trivial way. If a transaction writing data block A is 2167 * committing, we cannot discard the data by truncate until we have 2168 * written them. Otherwise if we crashed after the transaction with 2169 * write has committed but before the transaction with truncate has 2170 * committed, we could see stale data in block A. This function is a 2171 * helper to solve this problem. It starts writeout of the truncated 2172 * part in case it is in the committing transaction. 2173 * 2174 * Filesystem code must call this function when inode is journaled in 2175 * ordered mode before truncation happens and after the inode has been 2176 * placed on orphan list with the new inode size. The second condition 2177 * avoids the race that someone writes new data and we start 2178 * committing the transaction after this function has been called but 2179 * before a transaction for truncate is started (and furthermore it 2180 * allows us to optimize the case where the addition to orphan list 2181 * happens in the same transaction as write --- we don't have to write 2182 * any data in such case). 2183 */ 2184 int jbd2_journal_begin_ordered_truncate(journal_t *journal, 2185 struct jbd2_inode *jinode, 2186 loff_t new_size) 2187 { 2188 transaction_t *inode_trans, *commit_trans; 2189 int ret = 0; 2190 2191 /* This is a quick check to avoid locking if not necessary */ 2192 if (!jinode->i_transaction) 2193 goto out; 2194 /* Locks are here just to force reading of recent values, it is 2195 * enough that the transaction was not committing before we started 2196 * a transaction adding the inode to orphan list */ 2197 read_lock(&journal->j_state_lock); 2198 commit_trans = journal->j_committing_transaction; 2199 read_unlock(&journal->j_state_lock); 2200 spin_lock(&journal->j_list_lock); 2201 inode_trans = jinode->i_transaction; 2202 spin_unlock(&journal->j_list_lock); 2203 if (inode_trans == commit_trans) { 2204 ret = filemap_fdatawrite_range(jinode->i_vfs_inode->i_mapping, 2205 new_size, LLONG_MAX); 2206 if (ret) 2207 jbd2_journal_abort(journal, ret); 2208 } 2209 out: 2210 return ret; 2211 } 2212