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, *new_transaction = NULL; 121 tid_t tid; 122 int needed, need_to_start; 123 int nblocks = handle->h_buffer_credits; 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 tid = transaction->t_tid; 226 need_to_start = !tid_geq(journal->j_commit_request, tid); 227 read_unlock(&journal->j_state_lock); 228 if (need_to_start) 229 jbd2_log_start_commit(journal, tid); 230 schedule(); 231 finish_wait(&journal->j_wait_transaction_locked, &wait); 232 goto repeat; 233 } 234 235 /* 236 * The commit code assumes that it can get enough log space 237 * without forcing a checkpoint. This is *critical* for 238 * correctness: a checkpoint of a buffer which is also 239 * associated with a committing transaction creates a deadlock, 240 * so commit simply cannot force through checkpoints. 241 * 242 * We must therefore ensure the necessary space in the journal 243 * *before* starting to dirty potentially checkpointed buffers 244 * in the new transaction. 245 * 246 * The worst part is, any transaction currently committing can 247 * reduce the free space arbitrarily. Be careful to account for 248 * those buffers when checkpointing. 249 */ 250 251 /* 252 * @@@ AKPM: This seems rather over-defensive. We're giving commit 253 * a _lot_ of headroom: 1/4 of the journal plus the size of 254 * the committing transaction. Really, we only need to give it 255 * committing_transaction->t_outstanding_credits plus "enough" for 256 * the log control blocks. 257 * Also, this test is inconsistent with the matching one in 258 * jbd2_journal_extend(). 259 */ 260 if (__jbd2_log_space_left(journal) < jbd_space_needed(journal)) { 261 jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle); 262 atomic_sub(nblocks, &transaction->t_outstanding_credits); 263 read_unlock(&journal->j_state_lock); 264 write_lock(&journal->j_state_lock); 265 if (__jbd2_log_space_left(journal) < jbd_space_needed(journal)) 266 __jbd2_log_wait_for_space(journal); 267 write_unlock(&journal->j_state_lock); 268 goto repeat; 269 } 270 271 /* OK, account for the buffers that this operation expects to 272 * use and add the handle to the running transaction. 273 */ 274 update_t_max_wait(transaction); 275 handle->h_transaction = transaction; 276 atomic_inc(&transaction->t_updates); 277 atomic_inc(&transaction->t_handle_count); 278 jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n", 279 handle, nblocks, 280 atomic_read(&transaction->t_outstanding_credits), 281 __jbd2_log_space_left(journal)); 282 read_unlock(&journal->j_state_lock); 283 284 lock_map_acquire(&handle->h_lockdep_map); 285 kfree(new_transaction); 286 return 0; 287 } 288 289 static struct lock_class_key jbd2_handle_key; 290 291 /* Allocate a new handle. This should probably be in a slab... */ 292 static handle_t *new_handle(int nblocks) 293 { 294 handle_t *handle = jbd2_alloc_handle(GFP_NOFS); 295 if (!handle) 296 return NULL; 297 memset(handle, 0, sizeof(*handle)); 298 handle->h_buffer_credits = nblocks; 299 handle->h_ref = 1; 300 301 lockdep_init_map(&handle->h_lockdep_map, "jbd2_handle", 302 &jbd2_handle_key, 0); 303 304 return handle; 305 } 306 307 /** 308 * handle_t *jbd2_journal_start() - Obtain a new handle. 309 * @journal: Journal to start transaction on. 310 * @nblocks: number of block buffer we might modify 311 * 312 * We make sure that the transaction can guarantee at least nblocks of 313 * modified buffers in the log. We block until the log can guarantee 314 * that much space. 315 * 316 * This function is visible to journal users (like ext3fs), so is not 317 * called with the journal already locked. 318 * 319 * Return a pointer to a newly allocated handle, or NULL on failure 320 */ 321 handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int gfp_mask) 322 { 323 handle_t *handle = journal_current_handle(); 324 int err; 325 326 if (!journal) 327 return ERR_PTR(-EROFS); 328 329 if (handle) { 330 J_ASSERT(handle->h_transaction->t_journal == journal); 331 handle->h_ref++; 332 return handle; 333 } 334 335 handle = new_handle(nblocks); 336 if (!handle) 337 return ERR_PTR(-ENOMEM); 338 339 current->journal_info = handle; 340 341 err = start_this_handle(journal, handle, gfp_mask); 342 if (err < 0) { 343 jbd2_free_handle(handle); 344 current->journal_info = NULL; 345 handle = ERR_PTR(err); 346 } 347 return handle; 348 } 349 EXPORT_SYMBOL(jbd2__journal_start); 350 351 352 handle_t *jbd2_journal_start(journal_t *journal, int nblocks) 353 { 354 return jbd2__journal_start(journal, nblocks, GFP_NOFS); 355 } 356 EXPORT_SYMBOL(jbd2_journal_start); 357 358 359 /** 360 * int jbd2_journal_extend() - extend buffer credits. 361 * @handle: handle to 'extend' 362 * @nblocks: nr blocks to try to extend by. 363 * 364 * Some transactions, such as large extends and truncates, can be done 365 * atomically all at once or in several stages. The operation requests 366 * a credit for a number of buffer modications in advance, but can 367 * extend its credit if it needs more. 368 * 369 * jbd2_journal_extend tries to give the running handle more buffer credits. 370 * It does not guarantee that allocation - this is a best-effort only. 371 * The calling process MUST be able to deal cleanly with a failure to 372 * extend here. 373 * 374 * Return 0 on success, non-zero on failure. 375 * 376 * return code < 0 implies an error 377 * return code > 0 implies normal transaction-full status. 378 */ 379 int jbd2_journal_extend(handle_t *handle, int nblocks) 380 { 381 transaction_t *transaction = handle->h_transaction; 382 journal_t *journal = transaction->t_journal; 383 int result; 384 int wanted; 385 386 result = -EIO; 387 if (is_handle_aborted(handle)) 388 goto out; 389 390 result = 1; 391 392 read_lock(&journal->j_state_lock); 393 394 /* Don't extend a locked-down transaction! */ 395 if (handle->h_transaction->t_state != T_RUNNING) { 396 jbd_debug(3, "denied handle %p %d blocks: " 397 "transaction not running\n", handle, nblocks); 398 goto error_out; 399 } 400 401 spin_lock(&transaction->t_handle_lock); 402 wanted = atomic_read(&transaction->t_outstanding_credits) + nblocks; 403 404 if (wanted > journal->j_max_transaction_buffers) { 405 jbd_debug(3, "denied handle %p %d blocks: " 406 "transaction too large\n", handle, nblocks); 407 goto unlock; 408 } 409 410 if (wanted > __jbd2_log_space_left(journal)) { 411 jbd_debug(3, "denied handle %p %d blocks: " 412 "insufficient log space\n", handle, nblocks); 413 goto unlock; 414 } 415 416 handle->h_buffer_credits += nblocks; 417 atomic_add(nblocks, &transaction->t_outstanding_credits); 418 result = 0; 419 420 jbd_debug(3, "extended handle %p by %d\n", handle, nblocks); 421 unlock: 422 spin_unlock(&transaction->t_handle_lock); 423 error_out: 424 read_unlock(&journal->j_state_lock); 425 out: 426 return result; 427 } 428 429 430 /** 431 * int jbd2_journal_restart() - restart a handle . 432 * @handle: handle to restart 433 * @nblocks: nr credits requested 434 * 435 * Restart a handle for a multi-transaction filesystem 436 * operation. 437 * 438 * If the jbd2_journal_extend() call above fails to grant new buffer credits 439 * to a running handle, a call to jbd2_journal_restart will commit the 440 * handle's transaction so far and reattach the handle to a new 441 * transaction capabable of guaranteeing the requested number of 442 * credits. 443 */ 444 int jbd2__journal_restart(handle_t *handle, int nblocks, int gfp_mask) 445 { 446 transaction_t *transaction = handle->h_transaction; 447 journal_t *journal = transaction->t_journal; 448 tid_t tid; 449 int need_to_start, ret; 450 451 /* If we've had an abort of any type, don't even think about 452 * actually doing the restart! */ 453 if (is_handle_aborted(handle)) 454 return 0; 455 456 /* 457 * First unlink the handle from its current transaction, and start the 458 * commit on that. 459 */ 460 J_ASSERT(atomic_read(&transaction->t_updates) > 0); 461 J_ASSERT(journal_current_handle() == handle); 462 463 read_lock(&journal->j_state_lock); 464 spin_lock(&transaction->t_handle_lock); 465 atomic_sub(handle->h_buffer_credits, 466 &transaction->t_outstanding_credits); 467 if (atomic_dec_and_test(&transaction->t_updates)) 468 wake_up(&journal->j_wait_updates); 469 spin_unlock(&transaction->t_handle_lock); 470 471 jbd_debug(2, "restarting handle %p\n", handle); 472 tid = transaction->t_tid; 473 need_to_start = !tid_geq(journal->j_commit_request, tid); 474 read_unlock(&journal->j_state_lock); 475 if (need_to_start) 476 jbd2_log_start_commit(journal, tid); 477 478 lock_map_release(&handle->h_lockdep_map); 479 handle->h_buffer_credits = nblocks; 480 ret = start_this_handle(journal, handle, gfp_mask); 481 return ret; 482 } 483 EXPORT_SYMBOL(jbd2__journal_restart); 484 485 486 int jbd2_journal_restart(handle_t *handle, int nblocks) 487 { 488 return jbd2__journal_restart(handle, nblocks, GFP_NOFS); 489 } 490 EXPORT_SYMBOL(jbd2_journal_restart); 491 492 /** 493 * void jbd2_journal_lock_updates () - establish a transaction barrier. 494 * @journal: Journal to establish a barrier on. 495 * 496 * This locks out any further updates from being started, and blocks 497 * until all existing updates have completed, returning only once the 498 * journal is in a quiescent state with no updates running. 499 * 500 * The journal lock should not be held on entry. 501 */ 502 void jbd2_journal_lock_updates(journal_t *journal) 503 { 504 DEFINE_WAIT(wait); 505 506 write_lock(&journal->j_state_lock); 507 ++journal->j_barrier_count; 508 509 /* Wait until there are no running updates */ 510 while (1) { 511 transaction_t *transaction = journal->j_running_transaction; 512 513 if (!transaction) 514 break; 515 516 spin_lock(&transaction->t_handle_lock); 517 if (!atomic_read(&transaction->t_updates)) { 518 spin_unlock(&transaction->t_handle_lock); 519 break; 520 } 521 prepare_to_wait(&journal->j_wait_updates, &wait, 522 TASK_UNINTERRUPTIBLE); 523 spin_unlock(&transaction->t_handle_lock); 524 write_unlock(&journal->j_state_lock); 525 schedule(); 526 finish_wait(&journal->j_wait_updates, &wait); 527 write_lock(&journal->j_state_lock); 528 } 529 write_unlock(&journal->j_state_lock); 530 531 /* 532 * We have now established a barrier against other normal updates, but 533 * we also need to barrier against other jbd2_journal_lock_updates() calls 534 * to make sure that we serialise special journal-locked operations 535 * too. 536 */ 537 mutex_lock(&journal->j_barrier); 538 } 539 540 /** 541 * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier 542 * @journal: Journal to release the barrier on. 543 * 544 * Release a transaction barrier obtained with jbd2_journal_lock_updates(). 545 * 546 * Should be called without the journal lock held. 547 */ 548 void jbd2_journal_unlock_updates (journal_t *journal) 549 { 550 J_ASSERT(journal->j_barrier_count != 0); 551 552 mutex_unlock(&journal->j_barrier); 553 write_lock(&journal->j_state_lock); 554 --journal->j_barrier_count; 555 write_unlock(&journal->j_state_lock); 556 wake_up(&journal->j_wait_transaction_locked); 557 } 558 559 static void warn_dirty_buffer(struct buffer_head *bh) 560 { 561 char b[BDEVNAME_SIZE]; 562 563 printk(KERN_WARNING 564 "JBD: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). " 565 "There's a risk of filesystem corruption in case of system " 566 "crash.\n", 567 bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr); 568 } 569 570 /* 571 * If the buffer is already part of the current transaction, then there 572 * is nothing we need to do. If it is already part of a prior 573 * transaction which we are still committing to disk, then we need to 574 * make sure that we do not overwrite the old copy: we do copy-out to 575 * preserve the copy going to disk. We also account the buffer against 576 * the handle's metadata buffer credits (unless the buffer is already 577 * part of the transaction, that is). 578 * 579 */ 580 static int 581 do_get_write_access(handle_t *handle, struct journal_head *jh, 582 int force_copy) 583 { 584 struct buffer_head *bh; 585 transaction_t *transaction; 586 journal_t *journal; 587 int error; 588 char *frozen_buffer = NULL; 589 int need_copy = 0; 590 591 if (is_handle_aborted(handle)) 592 return -EROFS; 593 594 transaction = handle->h_transaction; 595 journal = transaction->t_journal; 596 597 jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy); 598 599 JBUFFER_TRACE(jh, "entry"); 600 repeat: 601 bh = jh2bh(jh); 602 603 /* @@@ Need to check for errors here at some point. */ 604 605 lock_buffer(bh); 606 jbd_lock_bh_state(bh); 607 608 /* We now hold the buffer lock so it is safe to query the buffer 609 * state. Is the buffer dirty? 610 * 611 * If so, there are two possibilities. The buffer may be 612 * non-journaled, and undergoing a quite legitimate writeback. 613 * Otherwise, it is journaled, and we don't expect dirty buffers 614 * in that state (the buffers should be marked JBD_Dirty 615 * instead.) So either the IO is being done under our own 616 * control and this is a bug, or it's a third party IO such as 617 * dump(8) (which may leave the buffer scheduled for read --- 618 * ie. locked but not dirty) or tune2fs (which may actually have 619 * the buffer dirtied, ugh.) */ 620 621 if (buffer_dirty(bh)) { 622 /* 623 * First question: is this buffer already part of the current 624 * transaction or the existing committing transaction? 625 */ 626 if (jh->b_transaction) { 627 J_ASSERT_JH(jh, 628 jh->b_transaction == transaction || 629 jh->b_transaction == 630 journal->j_committing_transaction); 631 if (jh->b_next_transaction) 632 J_ASSERT_JH(jh, jh->b_next_transaction == 633 transaction); 634 warn_dirty_buffer(bh); 635 } 636 /* 637 * In any case we need to clean the dirty flag and we must 638 * do it under the buffer lock to be sure we don't race 639 * with running write-out. 640 */ 641 JBUFFER_TRACE(jh, "Journalling dirty buffer"); 642 clear_buffer_dirty(bh); 643 set_buffer_jbddirty(bh); 644 } 645 646 unlock_buffer(bh); 647 648 error = -EROFS; 649 if (is_handle_aborted(handle)) { 650 jbd_unlock_bh_state(bh); 651 goto out; 652 } 653 error = 0; 654 655 /* 656 * The buffer is already part of this transaction if b_transaction or 657 * b_next_transaction points to it 658 */ 659 if (jh->b_transaction == transaction || 660 jh->b_next_transaction == transaction) 661 goto done; 662 663 /* 664 * this is the first time this transaction is touching this buffer, 665 * reset the modified flag 666 */ 667 jh->b_modified = 0; 668 669 /* 670 * If there is already a copy-out version of this buffer, then we don't 671 * need to make another one 672 */ 673 if (jh->b_frozen_data) { 674 JBUFFER_TRACE(jh, "has frozen data"); 675 J_ASSERT_JH(jh, jh->b_next_transaction == NULL); 676 jh->b_next_transaction = transaction; 677 goto done; 678 } 679 680 /* Is there data here we need to preserve? */ 681 682 if (jh->b_transaction && jh->b_transaction != transaction) { 683 JBUFFER_TRACE(jh, "owned by older transaction"); 684 J_ASSERT_JH(jh, jh->b_next_transaction == NULL); 685 J_ASSERT_JH(jh, jh->b_transaction == 686 journal->j_committing_transaction); 687 688 /* There is one case we have to be very careful about. 689 * If the committing transaction is currently writing 690 * this buffer out to disk and has NOT made a copy-out, 691 * then we cannot modify the buffer contents at all 692 * right now. The essence of copy-out is that it is the 693 * extra copy, not the primary copy, which gets 694 * journaled. If the primary copy is already going to 695 * disk then we cannot do copy-out here. */ 696 697 if (jh->b_jlist == BJ_Shadow) { 698 DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow); 699 wait_queue_head_t *wqh; 700 701 wqh = bit_waitqueue(&bh->b_state, BH_Unshadow); 702 703 JBUFFER_TRACE(jh, "on shadow: sleep"); 704 jbd_unlock_bh_state(bh); 705 /* commit wakes up all shadow buffers after IO */ 706 for ( ; ; ) { 707 prepare_to_wait(wqh, &wait.wait, 708 TASK_UNINTERRUPTIBLE); 709 if (jh->b_jlist != BJ_Shadow) 710 break; 711 schedule(); 712 } 713 finish_wait(wqh, &wait.wait); 714 goto repeat; 715 } 716 717 /* Only do the copy if the currently-owning transaction 718 * still needs it. If it is on the Forget list, the 719 * committing transaction is past that stage. The 720 * buffer had better remain locked during the kmalloc, 721 * but that should be true --- we hold the journal lock 722 * still and the buffer is already on the BUF_JOURNAL 723 * list so won't be flushed. 724 * 725 * Subtle point, though: if this is a get_undo_access, 726 * then we will be relying on the frozen_data to contain 727 * the new value of the committed_data record after the 728 * transaction, so we HAVE to force the frozen_data copy 729 * in that case. */ 730 731 if (jh->b_jlist != BJ_Forget || force_copy) { 732 JBUFFER_TRACE(jh, "generate frozen data"); 733 if (!frozen_buffer) { 734 JBUFFER_TRACE(jh, "allocate memory for buffer"); 735 jbd_unlock_bh_state(bh); 736 frozen_buffer = 737 jbd2_alloc(jh2bh(jh)->b_size, 738 GFP_NOFS); 739 if (!frozen_buffer) { 740 printk(KERN_EMERG 741 "%s: OOM for frozen_buffer\n", 742 __func__); 743 JBUFFER_TRACE(jh, "oom!"); 744 error = -ENOMEM; 745 jbd_lock_bh_state(bh); 746 goto done; 747 } 748 goto repeat; 749 } 750 jh->b_frozen_data = frozen_buffer; 751 frozen_buffer = NULL; 752 need_copy = 1; 753 } 754 jh->b_next_transaction = transaction; 755 } 756 757 758 /* 759 * Finally, if the buffer is not journaled right now, we need to make 760 * sure it doesn't get written to disk before the caller actually 761 * commits the new data 762 */ 763 if (!jh->b_transaction) { 764 JBUFFER_TRACE(jh, "no transaction"); 765 J_ASSERT_JH(jh, !jh->b_next_transaction); 766 jh->b_transaction = transaction; 767 JBUFFER_TRACE(jh, "file as BJ_Reserved"); 768 spin_lock(&journal->j_list_lock); 769 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved); 770 spin_unlock(&journal->j_list_lock); 771 } 772 773 done: 774 if (need_copy) { 775 struct page *page; 776 int offset; 777 char *source; 778 779 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)), 780 "Possible IO failure.\n"); 781 page = jh2bh(jh)->b_page; 782 offset = offset_in_page(jh2bh(jh)->b_data); 783 source = kmap_atomic(page, KM_USER0); 784 /* Fire data frozen trigger just before we copy the data */ 785 jbd2_buffer_frozen_trigger(jh, source + offset, 786 jh->b_triggers); 787 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size); 788 kunmap_atomic(source, KM_USER0); 789 790 /* 791 * Now that the frozen data is saved off, we need to store 792 * any matching triggers. 793 */ 794 jh->b_frozen_triggers = jh->b_triggers; 795 } 796 jbd_unlock_bh_state(bh); 797 798 /* 799 * If we are about to journal a buffer, then any revoke pending on it is 800 * no longer valid 801 */ 802 jbd2_journal_cancel_revoke(handle, jh); 803 804 out: 805 if (unlikely(frozen_buffer)) /* It's usually NULL */ 806 jbd2_free(frozen_buffer, bh->b_size); 807 808 JBUFFER_TRACE(jh, "exit"); 809 return error; 810 } 811 812 /** 813 * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update. 814 * @handle: transaction to add buffer modifications to 815 * @bh: bh to be used for metadata writes 816 * @credits: variable that will receive credits for the buffer 817 * 818 * Returns an error code or 0 on success. 819 * 820 * In full data journalling mode the buffer may be of type BJ_AsyncData, 821 * because we're write()ing a buffer which is also part of a shared mapping. 822 */ 823 824 int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh) 825 { 826 struct journal_head *jh = jbd2_journal_add_journal_head(bh); 827 int rc; 828 829 /* We do not want to get caught playing with fields which the 830 * log thread also manipulates. Make sure that the buffer 831 * completes any outstanding IO before proceeding. */ 832 rc = do_get_write_access(handle, jh, 0); 833 jbd2_journal_put_journal_head(jh); 834 return rc; 835 } 836 837 838 /* 839 * When the user wants to journal a newly created buffer_head 840 * (ie. getblk() returned a new buffer and we are going to populate it 841 * manually rather than reading off disk), then we need to keep the 842 * buffer_head locked until it has been completely filled with new 843 * data. In this case, we should be able to make the assertion that 844 * the bh is not already part of an existing transaction. 845 * 846 * The buffer should already be locked by the caller by this point. 847 * There is no lock ranking violation: it was a newly created, 848 * unlocked buffer beforehand. */ 849 850 /** 851 * int jbd2_journal_get_create_access () - notify intent to use newly created bh 852 * @handle: transaction to new buffer to 853 * @bh: new buffer. 854 * 855 * Call this if you create a new bh. 856 */ 857 int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh) 858 { 859 transaction_t *transaction = handle->h_transaction; 860 journal_t *journal = transaction->t_journal; 861 struct journal_head *jh = jbd2_journal_add_journal_head(bh); 862 int err; 863 864 jbd_debug(5, "journal_head %p\n", jh); 865 err = -EROFS; 866 if (is_handle_aborted(handle)) 867 goto out; 868 err = 0; 869 870 JBUFFER_TRACE(jh, "entry"); 871 /* 872 * The buffer may already belong to this transaction due to pre-zeroing 873 * in the filesystem's new_block code. It may also be on the previous, 874 * committing transaction's lists, but it HAS to be in Forget state in 875 * that case: the transaction must have deleted the buffer for it to be 876 * reused here. 877 */ 878 jbd_lock_bh_state(bh); 879 spin_lock(&journal->j_list_lock); 880 J_ASSERT_JH(jh, (jh->b_transaction == transaction || 881 jh->b_transaction == NULL || 882 (jh->b_transaction == journal->j_committing_transaction && 883 jh->b_jlist == BJ_Forget))); 884 885 J_ASSERT_JH(jh, jh->b_next_transaction == NULL); 886 J_ASSERT_JH(jh, buffer_locked(jh2bh(jh))); 887 888 if (jh->b_transaction == NULL) { 889 /* 890 * Previous jbd2_journal_forget() could have left the buffer 891 * with jbddirty bit set because it was being committed. When 892 * the commit finished, we've filed the buffer for 893 * checkpointing and marked it dirty. Now we are reallocating 894 * the buffer so the transaction freeing it must have 895 * committed and so it's safe to clear the dirty bit. 896 */ 897 clear_buffer_dirty(jh2bh(jh)); 898 jh->b_transaction = transaction; 899 900 /* first access by this transaction */ 901 jh->b_modified = 0; 902 903 JBUFFER_TRACE(jh, "file as BJ_Reserved"); 904 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved); 905 } else if (jh->b_transaction == journal->j_committing_transaction) { 906 /* first access by this transaction */ 907 jh->b_modified = 0; 908 909 JBUFFER_TRACE(jh, "set next transaction"); 910 jh->b_next_transaction = transaction; 911 } 912 spin_unlock(&journal->j_list_lock); 913 jbd_unlock_bh_state(bh); 914 915 /* 916 * akpm: I added this. ext3_alloc_branch can pick up new indirect 917 * blocks which contain freed but then revoked metadata. We need 918 * to cancel the revoke in case we end up freeing it yet again 919 * and the reallocating as data - this would cause a second revoke, 920 * which hits an assertion error. 921 */ 922 JBUFFER_TRACE(jh, "cancelling revoke"); 923 jbd2_journal_cancel_revoke(handle, jh); 924 jbd2_journal_put_journal_head(jh); 925 out: 926 return err; 927 } 928 929 /** 930 * int jbd2_journal_get_undo_access() - Notify intent to modify metadata with 931 * non-rewindable consequences 932 * @handle: transaction 933 * @bh: buffer to undo 934 * @credits: store the number of taken credits here (if not NULL) 935 * 936 * Sometimes there is a need to distinguish between metadata which has 937 * been committed to disk and that which has not. The ext3fs code uses 938 * this for freeing and allocating space, we have to make sure that we 939 * do not reuse freed space until the deallocation has been committed, 940 * since if we overwrote that space we would make the delete 941 * un-rewindable in case of a crash. 942 * 943 * To deal with that, jbd2_journal_get_undo_access requests write access to a 944 * buffer for parts of non-rewindable operations such as delete 945 * operations on the bitmaps. The journaling code must keep a copy of 946 * the buffer's contents prior to the undo_access call until such time 947 * as we know that the buffer has definitely been committed to disk. 948 * 949 * We never need to know which transaction the committed data is part 950 * of, buffers touched here are guaranteed to be dirtied later and so 951 * will be committed to a new transaction in due course, at which point 952 * we can discard the old committed data pointer. 953 * 954 * Returns error number or 0 on success. 955 */ 956 int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh) 957 { 958 int err; 959 struct journal_head *jh = jbd2_journal_add_journal_head(bh); 960 char *committed_data = NULL; 961 962 JBUFFER_TRACE(jh, "entry"); 963 964 /* 965 * Do this first --- it can drop the journal lock, so we want to 966 * make sure that obtaining the committed_data is done 967 * atomically wrt. completion of any outstanding commits. 968 */ 969 err = do_get_write_access(handle, jh, 1); 970 if (err) 971 goto out; 972 973 repeat: 974 if (!jh->b_committed_data) { 975 committed_data = jbd2_alloc(jh2bh(jh)->b_size, GFP_NOFS); 976 if (!committed_data) { 977 printk(KERN_EMERG "%s: No memory for committed data\n", 978 __func__); 979 err = -ENOMEM; 980 goto out; 981 } 982 } 983 984 jbd_lock_bh_state(bh); 985 if (!jh->b_committed_data) { 986 /* Copy out the current buffer contents into the 987 * preserved, committed copy. */ 988 JBUFFER_TRACE(jh, "generate b_committed data"); 989 if (!committed_data) { 990 jbd_unlock_bh_state(bh); 991 goto repeat; 992 } 993 994 jh->b_committed_data = committed_data; 995 committed_data = NULL; 996 memcpy(jh->b_committed_data, bh->b_data, bh->b_size); 997 } 998 jbd_unlock_bh_state(bh); 999 out: 1000 jbd2_journal_put_journal_head(jh); 1001 if (unlikely(committed_data)) 1002 jbd2_free(committed_data, bh->b_size); 1003 return err; 1004 } 1005 1006 /** 1007 * void jbd2_journal_set_triggers() - Add triggers for commit writeout 1008 * @bh: buffer to trigger on 1009 * @type: struct jbd2_buffer_trigger_type containing the trigger(s). 1010 * 1011 * Set any triggers on this journal_head. This is always safe, because 1012 * triggers for a committing buffer will be saved off, and triggers for 1013 * a running transaction will match the buffer in that transaction. 1014 * 1015 * Call with NULL to clear the triggers. 1016 */ 1017 void jbd2_journal_set_triggers(struct buffer_head *bh, 1018 struct jbd2_buffer_trigger_type *type) 1019 { 1020 struct journal_head *jh = bh2jh(bh); 1021 1022 jh->b_triggers = type; 1023 } 1024 1025 void jbd2_buffer_frozen_trigger(struct journal_head *jh, void *mapped_data, 1026 struct jbd2_buffer_trigger_type *triggers) 1027 { 1028 struct buffer_head *bh = jh2bh(jh); 1029 1030 if (!triggers || !triggers->t_frozen) 1031 return; 1032 1033 triggers->t_frozen(triggers, bh, mapped_data, bh->b_size); 1034 } 1035 1036 void jbd2_buffer_abort_trigger(struct journal_head *jh, 1037 struct jbd2_buffer_trigger_type *triggers) 1038 { 1039 if (!triggers || !triggers->t_abort) 1040 return; 1041 1042 triggers->t_abort(triggers, jh2bh(jh)); 1043 } 1044 1045 1046 1047 /** 1048 * int jbd2_journal_dirty_metadata() - mark a buffer as containing dirty metadata 1049 * @handle: transaction to add buffer to. 1050 * @bh: buffer to mark 1051 * 1052 * mark dirty metadata which needs to be journaled as part of the current 1053 * transaction. 1054 * 1055 * The buffer is placed on the transaction's metadata list and is marked 1056 * as belonging to the transaction. 1057 * 1058 * Returns error number or 0 on success. 1059 * 1060 * Special care needs to be taken if the buffer already belongs to the 1061 * current committing transaction (in which case we should have frozen 1062 * data present for that commit). In that case, we don't relink the 1063 * buffer: that only gets done when the old transaction finally 1064 * completes its commit. 1065 */ 1066 int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh) 1067 { 1068 transaction_t *transaction = handle->h_transaction; 1069 journal_t *journal = transaction->t_journal; 1070 struct journal_head *jh = bh2jh(bh); 1071 1072 jbd_debug(5, "journal_head %p\n", jh); 1073 JBUFFER_TRACE(jh, "entry"); 1074 if (is_handle_aborted(handle)) 1075 goto out; 1076 1077 jbd_lock_bh_state(bh); 1078 1079 if (jh->b_modified == 0) { 1080 /* 1081 * This buffer's got modified and becoming part 1082 * of the transaction. This needs to be done 1083 * once a transaction -bzzz 1084 */ 1085 jh->b_modified = 1; 1086 J_ASSERT_JH(jh, handle->h_buffer_credits > 0); 1087 handle->h_buffer_credits--; 1088 } 1089 1090 /* 1091 * fastpath, to avoid expensive locking. If this buffer is already 1092 * on the running transaction's metadata list there is nothing to do. 1093 * Nobody can take it off again because there is a handle open. 1094 * I _think_ we're OK here with SMP barriers - a mistaken decision will 1095 * result in this test being false, so we go in and take the locks. 1096 */ 1097 if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) { 1098 JBUFFER_TRACE(jh, "fastpath"); 1099 J_ASSERT_JH(jh, jh->b_transaction == 1100 journal->j_running_transaction); 1101 goto out_unlock_bh; 1102 } 1103 1104 set_buffer_jbddirty(bh); 1105 1106 /* 1107 * Metadata already on the current transaction list doesn't 1108 * need to be filed. Metadata on another transaction's list must 1109 * be committing, and will be refiled once the commit completes: 1110 * leave it alone for now. 1111 */ 1112 if (jh->b_transaction != transaction) { 1113 JBUFFER_TRACE(jh, "already on other transaction"); 1114 J_ASSERT_JH(jh, jh->b_transaction == 1115 journal->j_committing_transaction); 1116 J_ASSERT_JH(jh, jh->b_next_transaction == transaction); 1117 /* And this case is illegal: we can't reuse another 1118 * transaction's data buffer, ever. */ 1119 goto out_unlock_bh; 1120 } 1121 1122 /* That test should have eliminated the following case: */ 1123 J_ASSERT_JH(jh, jh->b_frozen_data == NULL); 1124 1125 JBUFFER_TRACE(jh, "file as BJ_Metadata"); 1126 spin_lock(&journal->j_list_lock); 1127 __jbd2_journal_file_buffer(jh, handle->h_transaction, BJ_Metadata); 1128 spin_unlock(&journal->j_list_lock); 1129 out_unlock_bh: 1130 jbd_unlock_bh_state(bh); 1131 out: 1132 JBUFFER_TRACE(jh, "exit"); 1133 return 0; 1134 } 1135 1136 /* 1137 * jbd2_journal_release_buffer: undo a get_write_access without any buffer 1138 * updates, if the update decided in the end that it didn't need access. 1139 * 1140 */ 1141 void 1142 jbd2_journal_release_buffer(handle_t *handle, struct buffer_head *bh) 1143 { 1144 BUFFER_TRACE(bh, "entry"); 1145 } 1146 1147 /** 1148 * void jbd2_journal_forget() - bforget() for potentially-journaled buffers. 1149 * @handle: transaction handle 1150 * @bh: bh to 'forget' 1151 * 1152 * We can only do the bforget if there are no commits pending against the 1153 * buffer. If the buffer is dirty in the current running transaction we 1154 * can safely unlink it. 1155 * 1156 * bh may not be a journalled buffer at all - it may be a non-JBD 1157 * buffer which came off the hashtable. Check for this. 1158 * 1159 * Decrements bh->b_count by one. 1160 * 1161 * Allow this call even if the handle has aborted --- it may be part of 1162 * the caller's cleanup after an abort. 1163 */ 1164 int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh) 1165 { 1166 transaction_t *transaction = handle->h_transaction; 1167 journal_t *journal = transaction->t_journal; 1168 struct journal_head *jh; 1169 int drop_reserve = 0; 1170 int err = 0; 1171 int was_modified = 0; 1172 1173 BUFFER_TRACE(bh, "entry"); 1174 1175 jbd_lock_bh_state(bh); 1176 spin_lock(&journal->j_list_lock); 1177 1178 if (!buffer_jbd(bh)) 1179 goto not_jbd; 1180 jh = bh2jh(bh); 1181 1182 /* Critical error: attempting to delete a bitmap buffer, maybe? 1183 * Don't do any jbd operations, and return an error. */ 1184 if (!J_EXPECT_JH(jh, !jh->b_committed_data, 1185 "inconsistent data on disk")) { 1186 err = -EIO; 1187 goto not_jbd; 1188 } 1189 1190 /* keep track of wether or not this transaction modified us */ 1191 was_modified = jh->b_modified; 1192 1193 /* 1194 * The buffer's going from the transaction, we must drop 1195 * all references -bzzz 1196 */ 1197 jh->b_modified = 0; 1198 1199 if (jh->b_transaction == handle->h_transaction) { 1200 J_ASSERT_JH(jh, !jh->b_frozen_data); 1201 1202 /* If we are forgetting a buffer which is already part 1203 * of this transaction, then we can just drop it from 1204 * the transaction immediately. */ 1205 clear_buffer_dirty(bh); 1206 clear_buffer_jbddirty(bh); 1207 1208 JBUFFER_TRACE(jh, "belongs to current transaction: unfile"); 1209 1210 /* 1211 * we only want to drop a reference if this transaction 1212 * modified the buffer 1213 */ 1214 if (was_modified) 1215 drop_reserve = 1; 1216 1217 /* 1218 * We are no longer going to journal this buffer. 1219 * However, the commit of this transaction is still 1220 * important to the buffer: the delete that we are now 1221 * processing might obsolete an old log entry, so by 1222 * committing, we can satisfy the buffer's checkpoint. 1223 * 1224 * So, if we have a checkpoint on the buffer, we should 1225 * now refile the buffer on our BJ_Forget list so that 1226 * we know to remove the checkpoint after we commit. 1227 */ 1228 1229 if (jh->b_cp_transaction) { 1230 __jbd2_journal_temp_unlink_buffer(jh); 1231 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget); 1232 } else { 1233 __jbd2_journal_unfile_buffer(jh); 1234 jbd2_journal_remove_journal_head(bh); 1235 __brelse(bh); 1236 if (!buffer_jbd(bh)) { 1237 spin_unlock(&journal->j_list_lock); 1238 jbd_unlock_bh_state(bh); 1239 __bforget(bh); 1240 goto drop; 1241 } 1242 } 1243 } else if (jh->b_transaction) { 1244 J_ASSERT_JH(jh, (jh->b_transaction == 1245 journal->j_committing_transaction)); 1246 /* However, if the buffer is still owned by a prior 1247 * (committing) transaction, we can't drop it yet... */ 1248 JBUFFER_TRACE(jh, "belongs to older transaction"); 1249 /* ... but we CAN drop it from the new transaction if we 1250 * have also modified it since the original commit. */ 1251 1252 if (jh->b_next_transaction) { 1253 J_ASSERT(jh->b_next_transaction == transaction); 1254 jh->b_next_transaction = NULL; 1255 1256 /* 1257 * only drop a reference if this transaction modified 1258 * the buffer 1259 */ 1260 if (was_modified) 1261 drop_reserve = 1; 1262 } 1263 } 1264 1265 not_jbd: 1266 spin_unlock(&journal->j_list_lock); 1267 jbd_unlock_bh_state(bh); 1268 __brelse(bh); 1269 drop: 1270 if (drop_reserve) { 1271 /* no need to reserve log space for this block -bzzz */ 1272 handle->h_buffer_credits++; 1273 } 1274 return err; 1275 } 1276 1277 /** 1278 * int jbd2_journal_stop() - complete a transaction 1279 * @handle: tranaction to complete. 1280 * 1281 * All done for a particular handle. 1282 * 1283 * There is not much action needed here. We just return any remaining 1284 * buffer credits to the transaction and remove the handle. The only 1285 * complication is that we need to start a commit operation if the 1286 * filesystem is marked for synchronous update. 1287 * 1288 * jbd2_journal_stop itself will not usually return an error, but it may 1289 * do so in unusual circumstances. In particular, expect it to 1290 * return -EIO if a jbd2_journal_abort has been executed since the 1291 * transaction began. 1292 */ 1293 int jbd2_journal_stop(handle_t *handle) 1294 { 1295 transaction_t *transaction = handle->h_transaction; 1296 journal_t *journal = transaction->t_journal; 1297 int err, wait_for_commit = 0; 1298 tid_t tid; 1299 pid_t pid; 1300 1301 J_ASSERT(journal_current_handle() == handle); 1302 1303 if (is_handle_aborted(handle)) 1304 err = -EIO; 1305 else { 1306 J_ASSERT(atomic_read(&transaction->t_updates) > 0); 1307 err = 0; 1308 } 1309 1310 if (--handle->h_ref > 0) { 1311 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1, 1312 handle->h_ref); 1313 return err; 1314 } 1315 1316 jbd_debug(4, "Handle %p going down\n", handle); 1317 1318 /* 1319 * Implement synchronous transaction batching. If the handle 1320 * was synchronous, don't force a commit immediately. Let's 1321 * yield and let another thread piggyback onto this 1322 * transaction. Keep doing that while new threads continue to 1323 * arrive. It doesn't cost much - we're about to run a commit 1324 * and sleep on IO anyway. Speeds up many-threaded, many-dir 1325 * operations by 30x or more... 1326 * 1327 * We try and optimize the sleep time against what the 1328 * underlying disk can do, instead of having a static sleep 1329 * time. This is useful for the case where our storage is so 1330 * fast that it is more optimal to go ahead and force a flush 1331 * and wait for the transaction to be committed than it is to 1332 * wait for an arbitrary amount of time for new writers to 1333 * join the transaction. We achieve this by measuring how 1334 * long it takes to commit a transaction, and compare it with 1335 * how long this transaction has been running, and if run time 1336 * < commit time then we sleep for the delta and commit. This 1337 * greatly helps super fast disks that would see slowdowns as 1338 * more threads started doing fsyncs. 1339 * 1340 * But don't do this if this process was the most recent one 1341 * to perform a synchronous write. We do this to detect the 1342 * case where a single process is doing a stream of sync 1343 * writes. No point in waiting for joiners in that case. 1344 */ 1345 pid = current->pid; 1346 if (handle->h_sync && journal->j_last_sync_writer != pid) { 1347 u64 commit_time, trans_time; 1348 1349 journal->j_last_sync_writer = pid; 1350 1351 read_lock(&journal->j_state_lock); 1352 commit_time = journal->j_average_commit_time; 1353 read_unlock(&journal->j_state_lock); 1354 1355 trans_time = ktime_to_ns(ktime_sub(ktime_get(), 1356 transaction->t_start_time)); 1357 1358 commit_time = max_t(u64, commit_time, 1359 1000*journal->j_min_batch_time); 1360 commit_time = min_t(u64, commit_time, 1361 1000*journal->j_max_batch_time); 1362 1363 if (trans_time < commit_time) { 1364 ktime_t expires = ktime_add_ns(ktime_get(), 1365 commit_time); 1366 set_current_state(TASK_UNINTERRUPTIBLE); 1367 schedule_hrtimeout(&expires, HRTIMER_MODE_ABS); 1368 } 1369 } 1370 1371 if (handle->h_sync) 1372 transaction->t_synchronous_commit = 1; 1373 current->journal_info = NULL; 1374 atomic_sub(handle->h_buffer_credits, 1375 &transaction->t_outstanding_credits); 1376 1377 /* 1378 * If the handle is marked SYNC, we need to set another commit 1379 * going! We also want to force a commit if the current 1380 * transaction is occupying too much of the log, or if the 1381 * transaction is too old now. 1382 */ 1383 if (handle->h_sync || 1384 (atomic_read(&transaction->t_outstanding_credits) > 1385 journal->j_max_transaction_buffers) || 1386 time_after_eq(jiffies, transaction->t_expires)) { 1387 /* Do this even for aborted journals: an abort still 1388 * completes the commit thread, it just doesn't write 1389 * anything to disk. */ 1390 1391 jbd_debug(2, "transaction too old, requesting commit for " 1392 "handle %p\n", handle); 1393 /* This is non-blocking */ 1394 jbd2_log_start_commit(journal, transaction->t_tid); 1395 1396 /* 1397 * Special case: JBD2_SYNC synchronous updates require us 1398 * to wait for the commit to complete. 1399 */ 1400 if (handle->h_sync && !(current->flags & PF_MEMALLOC)) 1401 wait_for_commit = 1; 1402 } 1403 1404 /* 1405 * Once we drop t_updates, if it goes to zero the transaction 1406 * could start commiting on us and eventually disappear. So 1407 * once we do this, we must not dereference transaction 1408 * pointer again. 1409 */ 1410 tid = transaction->t_tid; 1411 if (atomic_dec_and_test(&transaction->t_updates)) { 1412 wake_up(&journal->j_wait_updates); 1413 if (journal->j_barrier_count) 1414 wake_up(&journal->j_wait_transaction_locked); 1415 } 1416 1417 if (wait_for_commit) 1418 err = jbd2_log_wait_commit(journal, tid); 1419 1420 lock_map_release(&handle->h_lockdep_map); 1421 1422 jbd2_free_handle(handle); 1423 return err; 1424 } 1425 1426 /** 1427 * int jbd2_journal_force_commit() - force any uncommitted transactions 1428 * @journal: journal to force 1429 * 1430 * For synchronous operations: force any uncommitted transactions 1431 * to disk. May seem kludgy, but it reuses all the handle batching 1432 * code in a very simple manner. 1433 */ 1434 int jbd2_journal_force_commit(journal_t *journal) 1435 { 1436 handle_t *handle; 1437 int ret; 1438 1439 handle = jbd2_journal_start(journal, 1); 1440 if (IS_ERR(handle)) { 1441 ret = PTR_ERR(handle); 1442 } else { 1443 handle->h_sync = 1; 1444 ret = jbd2_journal_stop(handle); 1445 } 1446 return ret; 1447 } 1448 1449 /* 1450 * 1451 * List management code snippets: various functions for manipulating the 1452 * transaction buffer lists. 1453 * 1454 */ 1455 1456 /* 1457 * Append a buffer to a transaction list, given the transaction's list head 1458 * pointer. 1459 * 1460 * j_list_lock is held. 1461 * 1462 * jbd_lock_bh_state(jh2bh(jh)) is held. 1463 */ 1464 1465 static inline void 1466 __blist_add_buffer(struct journal_head **list, struct journal_head *jh) 1467 { 1468 if (!*list) { 1469 jh->b_tnext = jh->b_tprev = jh; 1470 *list = jh; 1471 } else { 1472 /* Insert at the tail of the list to preserve order */ 1473 struct journal_head *first = *list, *last = first->b_tprev; 1474 jh->b_tprev = last; 1475 jh->b_tnext = first; 1476 last->b_tnext = first->b_tprev = jh; 1477 } 1478 } 1479 1480 /* 1481 * Remove a buffer from a transaction list, given the transaction's list 1482 * head pointer. 1483 * 1484 * Called with j_list_lock held, and the journal may not be locked. 1485 * 1486 * jbd_lock_bh_state(jh2bh(jh)) is held. 1487 */ 1488 1489 static inline void 1490 __blist_del_buffer(struct journal_head **list, struct journal_head *jh) 1491 { 1492 if (*list == jh) { 1493 *list = jh->b_tnext; 1494 if (*list == jh) 1495 *list = NULL; 1496 } 1497 jh->b_tprev->b_tnext = jh->b_tnext; 1498 jh->b_tnext->b_tprev = jh->b_tprev; 1499 } 1500 1501 /* 1502 * Remove a buffer from the appropriate transaction list. 1503 * 1504 * Note that this function can *change* the value of 1505 * bh->b_transaction->t_buffers, t_forget, t_iobuf_list, t_shadow_list, 1506 * t_log_list or t_reserved_list. If the caller is holding onto a copy of one 1507 * of these pointers, it could go bad. Generally the caller needs to re-read 1508 * the pointer from the transaction_t. 1509 * 1510 * Called under j_list_lock. The journal may not be locked. 1511 */ 1512 void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh) 1513 { 1514 struct journal_head **list = NULL; 1515 transaction_t *transaction; 1516 struct buffer_head *bh = jh2bh(jh); 1517 1518 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); 1519 transaction = jh->b_transaction; 1520 if (transaction) 1521 assert_spin_locked(&transaction->t_journal->j_list_lock); 1522 1523 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types); 1524 if (jh->b_jlist != BJ_None) 1525 J_ASSERT_JH(jh, transaction != NULL); 1526 1527 switch (jh->b_jlist) { 1528 case BJ_None: 1529 return; 1530 case BJ_Metadata: 1531 transaction->t_nr_buffers--; 1532 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0); 1533 list = &transaction->t_buffers; 1534 break; 1535 case BJ_Forget: 1536 list = &transaction->t_forget; 1537 break; 1538 case BJ_IO: 1539 list = &transaction->t_iobuf_list; 1540 break; 1541 case BJ_Shadow: 1542 list = &transaction->t_shadow_list; 1543 break; 1544 case BJ_LogCtl: 1545 list = &transaction->t_log_list; 1546 break; 1547 case BJ_Reserved: 1548 list = &transaction->t_reserved_list; 1549 break; 1550 } 1551 1552 __blist_del_buffer(list, jh); 1553 jh->b_jlist = BJ_None; 1554 if (test_clear_buffer_jbddirty(bh)) 1555 mark_buffer_dirty(bh); /* Expose it to the VM */ 1556 } 1557 1558 void __jbd2_journal_unfile_buffer(struct journal_head *jh) 1559 { 1560 __jbd2_journal_temp_unlink_buffer(jh); 1561 jh->b_transaction = NULL; 1562 } 1563 1564 void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh) 1565 { 1566 jbd_lock_bh_state(jh2bh(jh)); 1567 spin_lock(&journal->j_list_lock); 1568 __jbd2_journal_unfile_buffer(jh); 1569 spin_unlock(&journal->j_list_lock); 1570 jbd_unlock_bh_state(jh2bh(jh)); 1571 } 1572 1573 /* 1574 * Called from jbd2_journal_try_to_free_buffers(). 1575 * 1576 * Called under jbd_lock_bh_state(bh) 1577 */ 1578 static void 1579 __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh) 1580 { 1581 struct journal_head *jh; 1582 1583 jh = bh2jh(bh); 1584 1585 if (buffer_locked(bh) || buffer_dirty(bh)) 1586 goto out; 1587 1588 if (jh->b_next_transaction != NULL) 1589 goto out; 1590 1591 spin_lock(&journal->j_list_lock); 1592 if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) { 1593 /* written-back checkpointed metadata buffer */ 1594 if (jh->b_jlist == BJ_None) { 1595 JBUFFER_TRACE(jh, "remove from checkpoint list"); 1596 __jbd2_journal_remove_checkpoint(jh); 1597 jbd2_journal_remove_journal_head(bh); 1598 __brelse(bh); 1599 } 1600 } 1601 spin_unlock(&journal->j_list_lock); 1602 out: 1603 return; 1604 } 1605 1606 /** 1607 * int jbd2_journal_try_to_free_buffers() - try to free page buffers. 1608 * @journal: journal for operation 1609 * @page: to try and free 1610 * @gfp_mask: we use the mask to detect how hard should we try to release 1611 * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to 1612 * release the buffers. 1613 * 1614 * 1615 * For all the buffers on this page, 1616 * if they are fully written out ordered data, move them onto BUF_CLEAN 1617 * so try_to_free_buffers() can reap them. 1618 * 1619 * This function returns non-zero if we wish try_to_free_buffers() 1620 * to be called. We do this if the page is releasable by try_to_free_buffers(). 1621 * We also do it if the page has locked or dirty buffers and the caller wants 1622 * us to perform sync or async writeout. 1623 * 1624 * This complicates JBD locking somewhat. We aren't protected by the 1625 * BKL here. We wish to remove the buffer from its committing or 1626 * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer. 1627 * 1628 * This may *change* the value of transaction_t->t_datalist, so anyone 1629 * who looks at t_datalist needs to lock against this function. 1630 * 1631 * Even worse, someone may be doing a jbd2_journal_dirty_data on this 1632 * buffer. So we need to lock against that. jbd2_journal_dirty_data() 1633 * will come out of the lock with the buffer dirty, which makes it 1634 * ineligible for release here. 1635 * 1636 * Who else is affected by this? hmm... Really the only contender 1637 * is do_get_write_access() - it could be looking at the buffer while 1638 * journal_try_to_free_buffer() is changing its state. But that 1639 * cannot happen because we never reallocate freed data as metadata 1640 * while the data is part of a transaction. Yes? 1641 * 1642 * Return 0 on failure, 1 on success 1643 */ 1644 int jbd2_journal_try_to_free_buffers(journal_t *journal, 1645 struct page *page, gfp_t gfp_mask) 1646 { 1647 struct buffer_head *head; 1648 struct buffer_head *bh; 1649 int ret = 0; 1650 1651 J_ASSERT(PageLocked(page)); 1652 1653 head = page_buffers(page); 1654 bh = head; 1655 do { 1656 struct journal_head *jh; 1657 1658 /* 1659 * We take our own ref against the journal_head here to avoid 1660 * having to add tons of locking around each instance of 1661 * jbd2_journal_remove_journal_head() and 1662 * jbd2_journal_put_journal_head(). 1663 */ 1664 jh = jbd2_journal_grab_journal_head(bh); 1665 if (!jh) 1666 continue; 1667 1668 jbd_lock_bh_state(bh); 1669 __journal_try_to_free_buffer(journal, bh); 1670 jbd2_journal_put_journal_head(jh); 1671 jbd_unlock_bh_state(bh); 1672 if (buffer_jbd(bh)) 1673 goto busy; 1674 } while ((bh = bh->b_this_page) != head); 1675 1676 ret = try_to_free_buffers(page); 1677 1678 busy: 1679 return ret; 1680 } 1681 1682 /* 1683 * This buffer is no longer needed. If it is on an older transaction's 1684 * checkpoint list we need to record it on this transaction's forget list 1685 * to pin this buffer (and hence its checkpointing transaction) down until 1686 * this transaction commits. If the buffer isn't on a checkpoint list, we 1687 * release it. 1688 * Returns non-zero if JBD no longer has an interest in the buffer. 1689 * 1690 * Called under j_list_lock. 1691 * 1692 * Called under jbd_lock_bh_state(bh). 1693 */ 1694 static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction) 1695 { 1696 int may_free = 1; 1697 struct buffer_head *bh = jh2bh(jh); 1698 1699 __jbd2_journal_unfile_buffer(jh); 1700 1701 if (jh->b_cp_transaction) { 1702 JBUFFER_TRACE(jh, "on running+cp transaction"); 1703 /* 1704 * We don't want to write the buffer anymore, clear the 1705 * bit so that we don't confuse checks in 1706 * __journal_file_buffer 1707 */ 1708 clear_buffer_dirty(bh); 1709 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget); 1710 may_free = 0; 1711 } else { 1712 JBUFFER_TRACE(jh, "on running transaction"); 1713 jbd2_journal_remove_journal_head(bh); 1714 __brelse(bh); 1715 } 1716 return may_free; 1717 } 1718 1719 /* 1720 * jbd2_journal_invalidatepage 1721 * 1722 * This code is tricky. It has a number of cases to deal with. 1723 * 1724 * There are two invariants which this code relies on: 1725 * 1726 * i_size must be updated on disk before we start calling invalidatepage on the 1727 * data. 1728 * 1729 * This is done in ext3 by defining an ext3_setattr method which 1730 * updates i_size before truncate gets going. By maintaining this 1731 * invariant, we can be sure that it is safe to throw away any buffers 1732 * attached to the current transaction: once the transaction commits, 1733 * we know that the data will not be needed. 1734 * 1735 * Note however that we can *not* throw away data belonging to the 1736 * previous, committing transaction! 1737 * 1738 * Any disk blocks which *are* part of the previous, committing 1739 * transaction (and which therefore cannot be discarded immediately) are 1740 * not going to be reused in the new running transaction 1741 * 1742 * The bitmap committed_data images guarantee this: any block which is 1743 * allocated in one transaction and removed in the next will be marked 1744 * as in-use in the committed_data bitmap, so cannot be reused until 1745 * the next transaction to delete the block commits. This means that 1746 * leaving committing buffers dirty is quite safe: the disk blocks 1747 * cannot be reallocated to a different file and so buffer aliasing is 1748 * not possible. 1749 * 1750 * 1751 * The above applies mainly to ordered data mode. In writeback mode we 1752 * don't make guarantees about the order in which data hits disk --- in 1753 * particular we don't guarantee that new dirty data is flushed before 1754 * transaction commit --- so it is always safe just to discard data 1755 * immediately in that mode. --sct 1756 */ 1757 1758 /* 1759 * The journal_unmap_buffer helper function returns zero if the buffer 1760 * concerned remains pinned as an anonymous buffer belonging to an older 1761 * transaction. 1762 * 1763 * We're outside-transaction here. Either or both of j_running_transaction 1764 * and j_committing_transaction may be NULL. 1765 */ 1766 static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh) 1767 { 1768 transaction_t *transaction; 1769 struct journal_head *jh; 1770 int may_free = 1; 1771 int ret; 1772 1773 BUFFER_TRACE(bh, "entry"); 1774 1775 /* 1776 * It is safe to proceed here without the j_list_lock because the 1777 * buffers cannot be stolen by try_to_free_buffers as long as we are 1778 * holding the page lock. --sct 1779 */ 1780 1781 if (!buffer_jbd(bh)) 1782 goto zap_buffer_unlocked; 1783 1784 /* OK, we have data buffer in journaled mode */ 1785 write_lock(&journal->j_state_lock); 1786 jbd_lock_bh_state(bh); 1787 spin_lock(&journal->j_list_lock); 1788 1789 jh = jbd2_journal_grab_journal_head(bh); 1790 if (!jh) 1791 goto zap_buffer_no_jh; 1792 1793 /* 1794 * We cannot remove the buffer from checkpoint lists until the 1795 * transaction adding inode to orphan list (let's call it T) 1796 * is committed. Otherwise if the transaction changing the 1797 * buffer would be cleaned from the journal before T is 1798 * committed, a crash will cause that the correct contents of 1799 * the buffer will be lost. On the other hand we have to 1800 * clear the buffer dirty bit at latest at the moment when the 1801 * transaction marking the buffer as freed in the filesystem 1802 * structures is committed because from that moment on the 1803 * buffer can be reallocated and used by a different page. 1804 * Since the block hasn't been freed yet but the inode has 1805 * already been added to orphan list, it is safe for us to add 1806 * the buffer to BJ_Forget list of the newest transaction. 1807 */ 1808 transaction = jh->b_transaction; 1809 if (transaction == NULL) { 1810 /* First case: not on any transaction. If it 1811 * has no checkpoint link, then we can zap it: 1812 * it's a writeback-mode buffer so we don't care 1813 * if it hits disk safely. */ 1814 if (!jh->b_cp_transaction) { 1815 JBUFFER_TRACE(jh, "not on any transaction: zap"); 1816 goto zap_buffer; 1817 } 1818 1819 if (!buffer_dirty(bh)) { 1820 /* bdflush has written it. We can drop it now */ 1821 goto zap_buffer; 1822 } 1823 1824 /* OK, it must be in the journal but still not 1825 * written fully to disk: it's metadata or 1826 * journaled data... */ 1827 1828 if (journal->j_running_transaction) { 1829 /* ... and once the current transaction has 1830 * committed, the buffer won't be needed any 1831 * longer. */ 1832 JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget"); 1833 ret = __dispose_buffer(jh, 1834 journal->j_running_transaction); 1835 jbd2_journal_put_journal_head(jh); 1836 spin_unlock(&journal->j_list_lock); 1837 jbd_unlock_bh_state(bh); 1838 write_unlock(&journal->j_state_lock); 1839 return ret; 1840 } else { 1841 /* There is no currently-running transaction. So the 1842 * orphan record which we wrote for this file must have 1843 * passed into commit. We must attach this buffer to 1844 * the committing transaction, if it exists. */ 1845 if (journal->j_committing_transaction) { 1846 JBUFFER_TRACE(jh, "give to committing trans"); 1847 ret = __dispose_buffer(jh, 1848 journal->j_committing_transaction); 1849 jbd2_journal_put_journal_head(jh); 1850 spin_unlock(&journal->j_list_lock); 1851 jbd_unlock_bh_state(bh); 1852 write_unlock(&journal->j_state_lock); 1853 return ret; 1854 } else { 1855 /* The orphan record's transaction has 1856 * committed. We can cleanse this buffer */ 1857 clear_buffer_jbddirty(bh); 1858 goto zap_buffer; 1859 } 1860 } 1861 } else if (transaction == journal->j_committing_transaction) { 1862 JBUFFER_TRACE(jh, "on committing transaction"); 1863 /* 1864 * The buffer is committing, we simply cannot touch 1865 * it. So we just set j_next_transaction to the 1866 * running transaction (if there is one) and mark 1867 * buffer as freed so that commit code knows it should 1868 * clear dirty bits when it is done with the buffer. 1869 */ 1870 set_buffer_freed(bh); 1871 if (journal->j_running_transaction && buffer_jbddirty(bh)) 1872 jh->b_next_transaction = journal->j_running_transaction; 1873 jbd2_journal_put_journal_head(jh); 1874 spin_unlock(&journal->j_list_lock); 1875 jbd_unlock_bh_state(bh); 1876 write_unlock(&journal->j_state_lock); 1877 return 0; 1878 } else { 1879 /* Good, the buffer belongs to the running transaction. 1880 * We are writing our own transaction's data, not any 1881 * previous one's, so it is safe to throw it away 1882 * (remember that we expect the filesystem to have set 1883 * i_size already for this truncate so recovery will not 1884 * expose the disk blocks we are discarding here.) */ 1885 J_ASSERT_JH(jh, transaction == journal->j_running_transaction); 1886 JBUFFER_TRACE(jh, "on running transaction"); 1887 may_free = __dispose_buffer(jh, transaction); 1888 } 1889 1890 zap_buffer: 1891 jbd2_journal_put_journal_head(jh); 1892 zap_buffer_no_jh: 1893 spin_unlock(&journal->j_list_lock); 1894 jbd_unlock_bh_state(bh); 1895 write_unlock(&journal->j_state_lock); 1896 zap_buffer_unlocked: 1897 clear_buffer_dirty(bh); 1898 J_ASSERT_BH(bh, !buffer_jbddirty(bh)); 1899 clear_buffer_mapped(bh); 1900 clear_buffer_req(bh); 1901 clear_buffer_new(bh); 1902 bh->b_bdev = NULL; 1903 return may_free; 1904 } 1905 1906 /** 1907 * void jbd2_journal_invalidatepage() 1908 * @journal: journal to use for flush... 1909 * @page: page to flush 1910 * @offset: length of page to invalidate. 1911 * 1912 * Reap page buffers containing data after offset in page. 1913 * 1914 */ 1915 void jbd2_journal_invalidatepage(journal_t *journal, 1916 struct page *page, 1917 unsigned long offset) 1918 { 1919 struct buffer_head *head, *bh, *next; 1920 unsigned int curr_off = 0; 1921 int may_free = 1; 1922 1923 if (!PageLocked(page)) 1924 BUG(); 1925 if (!page_has_buffers(page)) 1926 return; 1927 1928 /* We will potentially be playing with lists other than just the 1929 * data lists (especially for journaled data mode), so be 1930 * cautious in our locking. */ 1931 1932 head = bh = page_buffers(page); 1933 do { 1934 unsigned int next_off = curr_off + bh->b_size; 1935 next = bh->b_this_page; 1936 1937 if (offset <= curr_off) { 1938 /* This block is wholly outside the truncation point */ 1939 lock_buffer(bh); 1940 may_free &= journal_unmap_buffer(journal, bh); 1941 unlock_buffer(bh); 1942 } 1943 curr_off = next_off; 1944 bh = next; 1945 1946 } while (bh != head); 1947 1948 if (!offset) { 1949 if (may_free && try_to_free_buffers(page)) 1950 J_ASSERT(!page_has_buffers(page)); 1951 } 1952 } 1953 1954 /* 1955 * File a buffer on the given transaction list. 1956 */ 1957 void __jbd2_journal_file_buffer(struct journal_head *jh, 1958 transaction_t *transaction, int jlist) 1959 { 1960 struct journal_head **list = NULL; 1961 int was_dirty = 0; 1962 struct buffer_head *bh = jh2bh(jh); 1963 1964 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); 1965 assert_spin_locked(&transaction->t_journal->j_list_lock); 1966 1967 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types); 1968 J_ASSERT_JH(jh, jh->b_transaction == transaction || 1969 jh->b_transaction == NULL); 1970 1971 if (jh->b_transaction && jh->b_jlist == jlist) 1972 return; 1973 1974 if (jlist == BJ_Metadata || jlist == BJ_Reserved || 1975 jlist == BJ_Shadow || jlist == BJ_Forget) { 1976 /* 1977 * For metadata buffers, we track dirty bit in buffer_jbddirty 1978 * instead of buffer_dirty. We should not see a dirty bit set 1979 * here because we clear it in do_get_write_access but e.g. 1980 * tune2fs can modify the sb and set the dirty bit at any time 1981 * so we try to gracefully handle that. 1982 */ 1983 if (buffer_dirty(bh)) 1984 warn_dirty_buffer(bh); 1985 if (test_clear_buffer_dirty(bh) || 1986 test_clear_buffer_jbddirty(bh)) 1987 was_dirty = 1; 1988 } 1989 1990 if (jh->b_transaction) 1991 __jbd2_journal_temp_unlink_buffer(jh); 1992 jh->b_transaction = transaction; 1993 1994 switch (jlist) { 1995 case BJ_None: 1996 J_ASSERT_JH(jh, !jh->b_committed_data); 1997 J_ASSERT_JH(jh, !jh->b_frozen_data); 1998 return; 1999 case BJ_Metadata: 2000 transaction->t_nr_buffers++; 2001 list = &transaction->t_buffers; 2002 break; 2003 case BJ_Forget: 2004 list = &transaction->t_forget; 2005 break; 2006 case BJ_IO: 2007 list = &transaction->t_iobuf_list; 2008 break; 2009 case BJ_Shadow: 2010 list = &transaction->t_shadow_list; 2011 break; 2012 case BJ_LogCtl: 2013 list = &transaction->t_log_list; 2014 break; 2015 case BJ_Reserved: 2016 list = &transaction->t_reserved_list; 2017 break; 2018 } 2019 2020 __blist_add_buffer(list, jh); 2021 jh->b_jlist = jlist; 2022 2023 if (was_dirty) 2024 set_buffer_jbddirty(bh); 2025 } 2026 2027 void jbd2_journal_file_buffer(struct journal_head *jh, 2028 transaction_t *transaction, int jlist) 2029 { 2030 jbd_lock_bh_state(jh2bh(jh)); 2031 spin_lock(&transaction->t_journal->j_list_lock); 2032 __jbd2_journal_file_buffer(jh, transaction, jlist); 2033 spin_unlock(&transaction->t_journal->j_list_lock); 2034 jbd_unlock_bh_state(jh2bh(jh)); 2035 } 2036 2037 /* 2038 * Remove a buffer from its current buffer list in preparation for 2039 * dropping it from its current transaction entirely. If the buffer has 2040 * already started to be used by a subsequent transaction, refile the 2041 * buffer on that transaction's metadata list. 2042 * 2043 * Called under journal->j_list_lock 2044 * 2045 * Called under jbd_lock_bh_state(jh2bh(jh)) 2046 */ 2047 void __jbd2_journal_refile_buffer(struct journal_head *jh) 2048 { 2049 int was_dirty, jlist; 2050 struct buffer_head *bh = jh2bh(jh); 2051 2052 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh)); 2053 if (jh->b_transaction) 2054 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock); 2055 2056 /* If the buffer is now unused, just drop it. */ 2057 if (jh->b_next_transaction == NULL) { 2058 __jbd2_journal_unfile_buffer(jh); 2059 return; 2060 } 2061 2062 /* 2063 * It has been modified by a later transaction: add it to the new 2064 * transaction's metadata list. 2065 */ 2066 2067 was_dirty = test_clear_buffer_jbddirty(bh); 2068 __jbd2_journal_temp_unlink_buffer(jh); 2069 jh->b_transaction = jh->b_next_transaction; 2070 jh->b_next_transaction = NULL; 2071 if (buffer_freed(bh)) 2072 jlist = BJ_Forget; 2073 else if (jh->b_modified) 2074 jlist = BJ_Metadata; 2075 else 2076 jlist = BJ_Reserved; 2077 __jbd2_journal_file_buffer(jh, jh->b_transaction, jlist); 2078 J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING); 2079 2080 if (was_dirty) 2081 set_buffer_jbddirty(bh); 2082 } 2083 2084 /* 2085 * For the unlocked version of this call, also make sure that any 2086 * hanging journal_head is cleaned up if necessary. 2087 * 2088 * __jbd2_journal_refile_buffer is usually called as part of a single locked 2089 * operation on a buffer_head, in which the caller is probably going to 2090 * be hooking the journal_head onto other lists. In that case it is up 2091 * to the caller to remove the journal_head if necessary. For the 2092 * unlocked jbd2_journal_refile_buffer call, the caller isn't going to be 2093 * doing anything else to the buffer so we need to do the cleanup 2094 * ourselves to avoid a jh leak. 2095 * 2096 * *** The journal_head may be freed by this call! *** 2097 */ 2098 void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh) 2099 { 2100 struct buffer_head *bh = jh2bh(jh); 2101 2102 jbd_lock_bh_state(bh); 2103 spin_lock(&journal->j_list_lock); 2104 2105 __jbd2_journal_refile_buffer(jh); 2106 jbd_unlock_bh_state(bh); 2107 jbd2_journal_remove_journal_head(bh); 2108 2109 spin_unlock(&journal->j_list_lock); 2110 __brelse(bh); 2111 } 2112 2113 /* 2114 * File inode in the inode list of the handle's transaction 2115 */ 2116 int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode) 2117 { 2118 transaction_t *transaction = handle->h_transaction; 2119 journal_t *journal = transaction->t_journal; 2120 2121 if (is_handle_aborted(handle)) 2122 return -EIO; 2123 2124 jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode->i_vfs_inode->i_ino, 2125 transaction->t_tid); 2126 2127 /* 2128 * First check whether inode isn't already on the transaction's 2129 * lists without taking the lock. Note that this check is safe 2130 * without the lock as we cannot race with somebody removing inode 2131 * from the transaction. The reason is that we remove inode from the 2132 * transaction only in journal_release_jbd_inode() and when we commit 2133 * the transaction. We are guarded from the first case by holding 2134 * a reference to the inode. We are safe against the second case 2135 * because if jinode->i_transaction == transaction, commit code 2136 * cannot touch the transaction because we hold reference to it, 2137 * and if jinode->i_next_transaction == transaction, commit code 2138 * will only file the inode where we want it. 2139 */ 2140 if (jinode->i_transaction == transaction || 2141 jinode->i_next_transaction == transaction) 2142 return 0; 2143 2144 spin_lock(&journal->j_list_lock); 2145 2146 if (jinode->i_transaction == transaction || 2147 jinode->i_next_transaction == transaction) 2148 goto done; 2149 2150 /* On some different transaction's list - should be 2151 * the committing one */ 2152 if (jinode->i_transaction) { 2153 J_ASSERT(jinode->i_next_transaction == NULL); 2154 J_ASSERT(jinode->i_transaction == 2155 journal->j_committing_transaction); 2156 jinode->i_next_transaction = transaction; 2157 goto done; 2158 } 2159 /* Not on any transaction list... */ 2160 J_ASSERT(!jinode->i_next_transaction); 2161 jinode->i_transaction = transaction; 2162 list_add(&jinode->i_list, &transaction->t_inode_list); 2163 done: 2164 spin_unlock(&journal->j_list_lock); 2165 2166 return 0; 2167 } 2168 2169 /* 2170 * File truncate and transaction commit interact with each other in a 2171 * non-trivial way. If a transaction writing data block A is 2172 * committing, we cannot discard the data by truncate until we have 2173 * written them. Otherwise if we crashed after the transaction with 2174 * write has committed but before the transaction with truncate has 2175 * committed, we could see stale data in block A. This function is a 2176 * helper to solve this problem. It starts writeout of the truncated 2177 * part in case it is in the committing transaction. 2178 * 2179 * Filesystem code must call this function when inode is journaled in 2180 * ordered mode before truncation happens and after the inode has been 2181 * placed on orphan list with the new inode size. The second condition 2182 * avoids the race that someone writes new data and we start 2183 * committing the transaction after this function has been called but 2184 * before a transaction for truncate is started (and furthermore it 2185 * allows us to optimize the case where the addition to orphan list 2186 * happens in the same transaction as write --- we don't have to write 2187 * any data in such case). 2188 */ 2189 int jbd2_journal_begin_ordered_truncate(journal_t *journal, 2190 struct jbd2_inode *jinode, 2191 loff_t new_size) 2192 { 2193 transaction_t *inode_trans, *commit_trans; 2194 int ret = 0; 2195 2196 /* This is a quick check to avoid locking if not necessary */ 2197 if (!jinode->i_transaction) 2198 goto out; 2199 /* Locks are here just to force reading of recent values, it is 2200 * enough that the transaction was not committing before we started 2201 * a transaction adding the inode to orphan list */ 2202 read_lock(&journal->j_state_lock); 2203 commit_trans = journal->j_committing_transaction; 2204 read_unlock(&journal->j_state_lock); 2205 spin_lock(&journal->j_list_lock); 2206 inode_trans = jinode->i_transaction; 2207 spin_unlock(&journal->j_list_lock); 2208 if (inode_trans == commit_trans) { 2209 ret = filemap_fdatawrite_range(jinode->i_vfs_inode->i_mapping, 2210 new_size, LLONG_MAX); 2211 if (ret) 2212 jbd2_journal_abort(journal, ret); 2213 } 2214 out: 2215 return ret; 2216 } 2217