/fs/jbd2/transaction.c
C | 2225 lines | 1135 code | 248 blank | 842 comment | 224 complexity | aeb233a4b2fc90793f7b349382ba7d3a MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
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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 32static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh); 33static void __jbd2_journal_unfile_buffer(struct journal_head *jh); 34 35/* 36 * jbd2_get_transaction: obtain a new transaction_t object. 37 * 38 * Simply allocate and initialise a new transaction. Create it in 39 * RUNNING state and add it to the current journal (which should not 40 * have an existing running transaction: we only make a new transaction 41 * once we have started to commit the old one). 42 * 43 * Preconditions: 44 * The journal MUST be locked. We don't perform atomic mallocs on the 45 * new transaction and we can't block without protecting against other 46 * processes trying to touch the journal while it is in transition. 47 * 48 */ 49 50static transaction_t * 51jbd2_get_transaction(journal_t *journal, transaction_t *transaction) 52{ 53 transaction->t_journal = journal; 54 transaction->t_state = T_RUNNING; 55 transaction->t_start_time = ktime_get(); 56 transaction->t_tid = journal->j_transaction_sequence++; 57 transaction->t_expires = jiffies + journal->j_commit_interval; 58 spin_lock_init(&transaction->t_handle_lock); 59 atomic_set(&transaction->t_updates, 0); 60 atomic_set(&transaction->t_outstanding_credits, 0); 61 atomic_set(&transaction->t_handle_count, 0); 62 INIT_LIST_HEAD(&transaction->t_inode_list); 63 INIT_LIST_HEAD(&transaction->t_private_list); 64 65 /* Set up the commit timer for the new transaction. */ 66 journal->j_commit_timer.expires = round_jiffies_up(transaction->t_expires); 67 add_timer(&journal->j_commit_timer); 68 69 J_ASSERT(journal->j_running_transaction == NULL); 70 journal->j_running_transaction = transaction; 71 transaction->t_max_wait = 0; 72 transaction->t_start = jiffies; 73 74 return transaction; 75} 76 77/* 78 * Handle management. 79 * 80 * A handle_t is an object which represents a single atomic update to a 81 * filesystem, and which tracks all of the modifications which form part 82 * of that one update. 83 */ 84 85/* 86 * Update transaction's maximum wait time, if debugging is enabled. 87 * 88 * In order for t_max_wait to be reliable, it must be protected by a 89 * lock. But doing so will mean that start_this_handle() can not be 90 * run in parallel on SMP systems, which limits our scalability. So 91 * unless debugging is enabled, we no longer update t_max_wait, which 92 * means that maximum wait time reported by the jbd2_run_stats 93 * tracepoint will always be zero. 94 */ 95static inline void update_t_max_wait(transaction_t *transaction, 96 unsigned long ts) 97{ 98#ifdef CONFIG_JBD2_DEBUG 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 117static 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 unsigned long ts = jiffies; 125 126 if (nblocks > journal->j_max_transaction_buffers) { 127 printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n", 128 current->comm, nblocks, 129 journal->j_max_transaction_buffers); 130 return -ENOSPC; 131 } 132 133alloc_transaction: 134 if (!journal->j_running_transaction) { 135 new_transaction = kzalloc(sizeof(*new_transaction), gfp_mask); 136 if (!new_transaction) { 137 /* 138 * If __GFP_FS is not present, then we may be 139 * being called from inside the fs writeback 140 * layer, so we MUST NOT fail. Since 141 * __GFP_NOFAIL is going away, we will arrange 142 * to retry the allocation ourselves. 143 */ 144 if ((gfp_mask & __GFP_FS) == 0) { 145 congestion_wait(BLK_RW_ASYNC, HZ/50); 146 goto alloc_transaction; 147 } 148 return -ENOMEM; 149 } 150 } 151 152 jbd_debug(3, "New handle %p going live.\n", handle); 153 154 /* 155 * We need to hold j_state_lock until t_updates has been incremented, 156 * for proper journal barrier handling 157 */ 158repeat: 159 read_lock(&journal->j_state_lock); 160 BUG_ON(journal->j_flags & JBD2_UNMOUNT); 161 if (is_journal_aborted(journal) || 162 (journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) { 163 read_unlock(&journal->j_state_lock); 164 kfree(new_transaction); 165 return -EROFS; 166 } 167 168 /* Wait on the journal's transaction barrier if necessary */ 169 if (journal->j_barrier_count) { 170 read_unlock(&journal->j_state_lock); 171 wait_event(journal->j_wait_transaction_locked, 172 journal->j_barrier_count == 0); 173 goto repeat; 174 } 175 176 if (!journal->j_running_transaction) { 177 read_unlock(&journal->j_state_lock); 178 if (!new_transaction) 179 goto alloc_transaction; 180 write_lock(&journal->j_state_lock); 181 if (!journal->j_running_transaction) { 182 jbd2_get_transaction(journal, new_transaction); 183 new_transaction = NULL; 184 } 185 write_unlock(&journal->j_state_lock); 186 goto repeat; 187 } 188 189 transaction = journal->j_running_transaction; 190 191 /* 192 * If the current transaction is locked down for commit, wait for the 193 * lock to be released. 194 */ 195 if (transaction->t_state == T_LOCKED) { 196 DEFINE_WAIT(wait); 197 198 prepare_to_wait(&journal->j_wait_transaction_locked, 199 &wait, TASK_UNINTERRUPTIBLE); 200 read_unlock(&journal->j_state_lock); 201 schedule(); 202 finish_wait(&journal->j_wait_transaction_locked, &wait); 203 goto repeat; 204 } 205 206 /* 207 * If there is not enough space left in the log to write all potential 208 * buffers requested by this operation, we need to stall pending a log 209 * checkpoint to free some more log space. 210 */ 211 needed = atomic_add_return(nblocks, 212 &transaction->t_outstanding_credits); 213 214 if (needed > journal->j_max_transaction_buffers) { 215 /* 216 * If the current transaction is already too large, then start 217 * to commit it: we can then go back and attach this handle to 218 * a new transaction. 219 */ 220 DEFINE_WAIT(wait); 221 222 jbd_debug(2, "Handle %p starting new commit...\n", handle); 223 atomic_sub(nblocks, &transaction->t_outstanding_credits); 224 prepare_to_wait(&journal->j_wait_transaction_locked, &wait, 225 TASK_UNINTERRUPTIBLE); 226 tid = transaction->t_tid; 227 need_to_start = !tid_geq(journal->j_commit_request, tid); 228 read_unlock(&journal->j_state_lock); 229 if (need_to_start) 230 jbd2_log_start_commit(journal, tid); 231 schedule(); 232 finish_wait(&journal->j_wait_transaction_locked, &wait); 233 goto repeat; 234 } 235 236 /* 237 * The commit code assumes that it can get enough log space 238 * without forcing a checkpoint. This is *critical* for 239 * correctness: a checkpoint of a buffer which is also 240 * associated with a committing transaction creates a deadlock, 241 * so commit simply cannot force through checkpoints. 242 * 243 * We must therefore ensure the necessary space in the journal 244 * *before* starting to dirty potentially checkpointed buffers 245 * in the new transaction. 246 * 247 * The worst part is, any transaction currently committing can 248 * reduce the free space arbitrarily. Be careful to account for 249 * those buffers when checkpointing. 250 */ 251 252 /* 253 * @@@ AKPM: This seems rather over-defensive. We're giving commit 254 * a _lot_ of headroom: 1/4 of the journal plus the size of 255 * the committing transaction. Really, we only need to give it 256 * committing_transaction->t_outstanding_credits plus "enough" for 257 * the log control blocks. 258 * Also, this test is inconsistent with the matching one in 259 * jbd2_journal_extend(). 260 */ 261 if (__jbd2_log_space_left(journal) < jbd_space_needed(journal)) { 262 jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle); 263 atomic_sub(nblocks, &transaction->t_outstanding_credits); 264 read_unlock(&journal->j_state_lock); 265 write_lock(&journal->j_state_lock); 266 if (__jbd2_log_space_left(journal) < jbd_space_needed(journal)) 267 __jbd2_log_wait_for_space(journal); 268 write_unlock(&journal->j_state_lock); 269 goto repeat; 270 } 271 272 /* OK, account for the buffers that this operation expects to 273 * use and add the handle to the running transaction. 274 */ 275 update_t_max_wait(transaction, ts); 276 handle->h_transaction = transaction; 277 atomic_inc(&transaction->t_updates); 278 atomic_inc(&transaction->t_handle_count); 279 jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n", 280 handle, nblocks, 281 atomic_read(&transaction->t_outstanding_credits), 282 __jbd2_log_space_left(journal)); 283 read_unlock(&journal->j_state_lock); 284 285 lock_map_acquire(&handle->h_lockdep_map); 286 kfree(new_transaction); 287 return 0; 288} 289 290static struct lock_class_key jbd2_handle_key; 291 292/* Allocate a new handle. This should probably be in a slab... */ 293static handle_t *new_handle(int nblocks) 294{ 295 handle_t *handle = jbd2_alloc_handle(GFP_NOFS); 296 if (!handle) 297 return NULL; 298 memset(handle, 0, sizeof(*handle)); 299 handle->h_buffer_credits = nblocks; 300 handle->h_ref = 1; 301 302 lockdep_init_map(&handle->h_lockdep_map, "jbd2_handle", 303 &jbd2_handle_key, 0); 304 305 return handle; 306} 307 308/** 309 * handle_t *jbd2_journal_start() - Obtain a new handle. 310 * @journal: Journal to start transaction on. 311 * @nblocks: number of block buffer we might modify 312 * 313 * We make sure that the transaction can guarantee at least nblocks of 314 * modified buffers in the log. We block until the log can guarantee 315 * that much space. 316 * 317 * This function is visible to journal users (like ext3fs), so is not 318 * called with the journal already locked. 319 * 320 * Return a pointer to a newly allocated handle, or an ERR_PTR() value 321 * on failure. 322 */ 323handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int gfp_mask) 324{ 325 handle_t *handle = journal_current_handle(); 326 int err; 327 328 if (!journal) 329 return ERR_PTR(-EROFS); 330 331 if (handle) { 332 J_ASSERT(handle->h_transaction->t_journal == journal); 333 handle->h_ref++; 334 return handle; 335 } 336 337 handle = new_handle(nblocks); 338 if (!handle) 339 return ERR_PTR(-ENOMEM); 340 341 current->journal_info = handle; 342 343 err = start_this_handle(journal, handle, gfp_mask); 344 if (err < 0) { 345 jbd2_free_handle(handle); 346 current->journal_info = NULL; 347 handle = ERR_PTR(err); 348 } 349 return handle; 350} 351EXPORT_SYMBOL(jbd2__journal_start); 352 353 354handle_t *jbd2_journal_start(journal_t *journal, int nblocks) 355{ 356 return jbd2__journal_start(journal, nblocks, GFP_NOFS); 357} 358EXPORT_SYMBOL(jbd2_journal_start); 359 360 361/** 362 * int jbd2_journal_extend() - extend buffer credits. 363 * @handle: handle to 'extend' 364 * @nblocks: nr blocks to try to extend by. 365 * 366 * Some transactions, such as large extends and truncates, can be done 367 * atomically all at once or in several stages. The operation requests 368 * a credit for a number of buffer modications in advance, but can 369 * extend its credit if it needs more. 370 * 371 * jbd2_journal_extend tries to give the running handle more buffer credits. 372 * It does not guarantee that allocation - this is a best-effort only. 373 * The calling process MUST be able to deal cleanly with a failure to 374 * extend here. 375 * 376 * Return 0 on success, non-zero on failure. 377 * 378 * return code < 0 implies an error 379 * return code > 0 implies normal transaction-full status. 380 */ 381int jbd2_journal_extend(handle_t *handle, int nblocks) 382{ 383 transaction_t *transaction = handle->h_transaction; 384 journal_t *journal = transaction->t_journal; 385 int result; 386 int wanted; 387 388 result = -EIO; 389 if (is_handle_aborted(handle)) 390 goto out; 391 392 result = 1; 393 394 read_lock(&journal->j_state_lock); 395 396 /* Don't extend a locked-down transaction! */ 397 if (handle->h_transaction->t_state != T_RUNNING) { 398 jbd_debug(3, "denied handle %p %d blocks: " 399 "transaction not running\n", handle, nblocks); 400 goto error_out; 401 } 402 403 spin_lock(&transaction->t_handle_lock); 404 wanted = atomic_read(&transaction->t_outstanding_credits) + nblocks; 405 406 if (wanted > journal->j_max_transaction_buffers) { 407 jbd_debug(3, "denied handle %p %d blocks: " 408 "transaction too large\n", handle, nblocks); 409 goto unlock; 410 } 411 412 if (wanted > __jbd2_log_space_left(journal)) { 413 jbd_debug(3, "denied handle %p %d blocks: " 414 "insufficient log space\n", handle, nblocks); 415 goto unlock; 416 } 417 418 handle->h_buffer_credits += nblocks; 419 atomic_add(nblocks, &transaction->t_outstanding_credits); 420 result = 0; 421 422 jbd_debug(3, "extended handle %p by %d\n", handle, nblocks); 423unlock: 424 spin_unlock(&transaction->t_handle_lock); 425error_out: 426 read_unlock(&journal->j_state_lock); 427out: 428 return result; 429} 430 431 432/** 433 * int jbd2_journal_restart() - restart a handle . 434 * @handle: handle to restart 435 * @nblocks: nr credits requested 436 * 437 * Restart a handle for a multi-transaction filesystem 438 * operation. 439 * 440 * If the jbd2_journal_extend() call above fails to grant new buffer credits 441 * to a running handle, a call to jbd2_journal_restart will commit the 442 * handle's transaction so far and reattach the handle to a new 443 * transaction capabable of guaranteeing the requested number of 444 * credits. 445 */ 446int jbd2__journal_restart(handle_t *handle, int nblocks, int gfp_mask) 447{ 448 transaction_t *transaction = handle->h_transaction; 449 journal_t *journal = transaction->t_journal; 450 tid_t tid; 451 int need_to_start, ret; 452 453 /* If we've had an abort of any type, don't even think about 454 * actually doing the restart! */ 455 if (is_handle_aborted(handle)) 456 return 0; 457 458 /* 459 * First unlink the handle from its current transaction, and start the 460 * commit on that. 461 */ 462 J_ASSERT(atomic_read(&transaction->t_updates) > 0); 463 J_ASSERT(journal_current_handle() == handle); 464 465 read_lock(&journal->j_state_lock); 466 spin_lock(&transaction->t_handle_lock); 467 atomic_sub(handle->h_buffer_credits, 468 &transaction->t_outstanding_credits); 469 if (atomic_dec_and_test(&transaction->t_updates)) 470 wake_up(&journal->j_wait_updates); 471 spin_unlock(&transaction->t_handle_lock); 472 473 jbd_debug(2, "restarting handle %p\n", handle); 474 tid = transaction->t_tid; 475 need_to_start = !tid_geq(journal->j_commit_request, tid); 476 read_unlock(&journal->j_state_lock); 477 if (need_to_start) 478 jbd2_log_start_commit(journal, tid); 479 480 lock_map_release(&handle->h_lockdep_map); 481 handle->h_buffer_credits = nblocks; 482 ret = start_this_handle(journal, handle, gfp_mask); 483 return ret; 484} 485EXPORT_SYMBOL(jbd2__journal_restart); 486 487 488int jbd2_journal_restart(handle_t *handle, int nblocks) 489{ 490 return jbd2__journal_restart(handle, nblocks, GFP_NOFS); 491} 492EXPORT_SYMBOL(jbd2_journal_restart); 493 494/** 495 * void jbd2_journal_lock_updates () - establish a transaction barrier. 496 * @journal: Journal to establish a barrier on. 497 * 498 * This locks out any further updates from being started, and blocks 499 * until all existing updates have completed, returning only once the 500 * journal is in a quiescent state with no updates running. 501 * 502 * The journal lock should not be held on entry. 503 */ 504void jbd2_journal_lock_updates(journal_t *journal) 505{ 506 DEFINE_WAIT(wait); 507 508 write_lock(&journal->j_state_lock); 509 ++journal->j_barrier_count; 510 511 /* Wait until there are no running updates */ 512 while (1) { 513 transaction_t *transaction = journal->j_running_transaction; 514 515 if (!transaction) 516 break; 517 518 spin_lock(&transaction->t_handle_lock); 519 if (!atomic_read(&transaction->t_updates)) { 520 spin_unlock(&transaction->t_handle_lock); 521 break; 522 } 523 prepare_to_wait(&journal->j_wait_updates, &wait, 524 TASK_UNINTERRUPTIBLE); 525 spin_unlock(&transaction->t_handle_lock); 526 write_unlock(&journal->j_state_lock); 527 schedule(); 528 finish_wait(&journal->j_wait_updates, &wait); 529 write_lock(&journal->j_state_lock); 530 } 531 write_unlock(&journal->j_state_lock); 532 533 /* 534 * We have now established a barrier against other normal updates, but 535 * we also need to barrier against other jbd2_journal_lock_updates() calls 536 * to make sure that we serialise special journal-locked operations 537 * too. 538 */ 539 mutex_lock(&journal->j_barrier); 540} 541 542/** 543 * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier 544 * @journal: Journal to release the barrier on. 545 * 546 * Release a transaction barrier obtained with jbd2_journal_lock_updates(). 547 * 548 * Should be called without the journal lock held. 549 */ 550void jbd2_journal_unlock_updates (journal_t *journal) 551{ 552 J_ASSERT(journal->j_barrier_count != 0); 553 554 mutex_unlock(&journal->j_barrier); 555 write_lock(&journal->j_state_lock); 556 --journal->j_barrier_count; 557 write_unlock(&journal->j_state_lock); 558 wake_up(&journal->j_wait_transaction_locked); 559} 560 561static void warn_dirty_buffer(struct buffer_head *bh) 562{ 563 char b[BDEVNAME_SIZE]; 564 565 printk(KERN_WARNING 566 "JBD: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). " 567 "There's a risk of filesystem corruption in case of system " 568 "crash.\n", 569 bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr); 570} 571 572/* 573 * If the buffer is already part of the current transaction, then there 574 * is nothing we need to do. If it is already part of a prior 575 * transaction which we are still committing to disk, then we need to 576 * make sure that we do not overwrite the old copy: we do copy-out to 577 * preserve the copy going to disk. We also account the buffer against 578 * the handle's metadata buffer credits (unless the buffer is already 579 * part of the transaction, that is). 580 * 581 */ 582static int 583do_get_write_access(handle_t *handle, struct journal_head *jh, 584 int force_copy) 585{ 586 struct buffer_head *bh; 587 transaction_t *transaction; 588 journal_t *journal; 589 int error; 590 char *frozen_buffer = NULL; 591 int need_copy = 0; 592 593 if (is_handle_aborted(handle)) 594 return -EROFS; 595 596 transaction = handle->h_transaction; 597 journal = transaction->t_journal; 598 599 jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy); 600 601 JBUFFER_TRACE(jh, "entry"); 602repeat: 603 bh = jh2bh(jh); 604 605 /* @@@ Need to check for errors here at some point. */ 606 607 lock_buffer(bh); 608 jbd_lock_bh_state(bh); 609 610 /* We now hold the buffer lock so it is safe to query the buffer 611 * state. Is the buffer dirty? 612 * 613 * If so, there are two possibilities. The buffer may be 614 * non-journaled, and undergoing a quite legitimate writeback. 615 * Otherwise, it is journaled, and we don't expect dirty buffers 616 * in that state (the buffers should be marked JBD_Dirty 617 * instead.) So either the IO is being done under our own 618 * control and this is a bug, or it's a third party IO such as 619 * dump(8) (which may leave the buffer scheduled for read --- 620 * ie. locked but not dirty) or tune2fs (which may actually have 621 * the buffer dirtied, ugh.) */ 622 623 if (buffer_dirty(bh)) { 624 /* 625 * First question: is this buffer already part of the current 626 * transaction or the existing committing transaction? 627 */ 628 if (jh->b_transaction) { 629 J_ASSERT_JH(jh, 630 jh->b_transaction == transaction || 631 jh->b_transaction == 632 journal->j_committing_transaction); 633 if (jh->b_next_transaction) 634 J_ASSERT_JH(jh, jh->b_next_transaction == 635 transaction); 636 warn_dirty_buffer(bh); 637 } 638 /* 639 * In any case we need to clean the dirty flag and we must 640 * do it under the buffer lock to be sure we don't race 641 * with running write-out. 642 */ 643 JBUFFER_TRACE(jh, "Journalling dirty buffer"); 644 clear_buffer_dirty(bh); 645 set_buffer_jbddirty(bh); 646 } 647 648 unlock_buffer(bh); 649 650 error = -EROFS; 651 if (is_handle_aborted(handle)) { 652 jbd_unlock_bh_state(bh); 653 goto out; 654 } 655 error = 0; 656 657 /* 658 * The buffer is already part of this transaction if b_transaction or 659 * b_next_transaction points to it 660 */ 661 if (jh->b_transaction == transaction || 662 jh->b_next_transaction == transaction) 663 goto done; 664 665 /* 666 * this is the first time this transaction is touching this buffer, 667 * reset the modified flag 668 */ 669 jh->b_modified = 0; 670 671 /* 672 * If there is already a copy-out version of this buffer, then we don't 673 * need to make another one 674 */ 675 if (jh->b_frozen_data) { 676 JBUFFER_TRACE(jh, "has frozen data"); 677 J_ASSERT_JH(jh, jh->b_next_transaction == NULL); 678 jh->b_next_transaction = transaction; 679 goto done; 680 } 681 682 /* Is there data here we need to preserve? */ 683 684 if (jh->b_transaction && jh->b_transaction != transaction) { 685 JBUFFER_TRACE(jh, "owned by older transaction"); 686 J_ASSERT_JH(jh, jh->b_next_transaction == NULL); 687 J_ASSERT_JH(jh, jh->b_transaction == 688 journal->j_committing_transaction); 689 690 /* There is one case we have to be very careful about. 691 * If the committing transaction is currently writing 692 * this buffer out to disk and has NOT made a copy-out, 693 * then we cannot modify the buffer contents at all 694 * right now. The essence of copy-out is that it is the 695 * extra copy, not the primary copy, which gets 696 * journaled. If the primary copy is already going to 697 * disk then we cannot do copy-out here. */ 698 699 if (jh->b_jlist == BJ_Shadow) { 700 DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow); 701 wait_queue_head_t *wqh; 702 703 wqh = bit_waitqueue(&bh->b_state, BH_Unshadow); 704 705 JBUFFER_TRACE(jh, "on shadow: sleep"); 706 jbd_unlock_bh_state(bh); 707 /* commit wakes up all shadow buffers after IO */ 708 for ( ; ; ) { 709 prepare_to_wait(wqh, &wait.wait, 710 TASK_UNINTERRUPTIBLE); 711 if (jh->b_jlist != BJ_Shadow) 712 break; 713 schedule(); 714 } 715 finish_wait(wqh, &wait.wait); 716 goto repeat; 717 } 718 719 /* Only do the copy if the currently-owning transaction 720 * still needs it. If it is on the Forget list, the 721 * committing transaction is past that stage. The 722 * buffer had better remain locked during the kmalloc, 723 * but that should be true --- we hold the journal lock 724 * still and the buffer is already on the BUF_JOURNAL 725 * list so won't be flushed. 726 * 727 * Subtle point, though: if this is a get_undo_access, 728 * then we will be relying on the frozen_data to contain 729 * the new value of the committed_data record after the 730 * transaction, so we HAVE to force the frozen_data copy 731 * in that case. */ 732 733 if (jh->b_jlist != BJ_Forget || force_copy) { 734 JBUFFER_TRACE(jh, "generate frozen data"); 735 if (!frozen_buffer) { 736 JBUFFER_TRACE(jh, "allocate memory for buffer"); 737 jbd_unlock_bh_state(bh); 738 frozen_buffer = 739 jbd2_alloc(jh2bh(jh)->b_size, 740 GFP_NOFS); 741 if (!frozen_buffer) { 742 printk(KERN_EMERG 743 "%s: OOM for frozen_buffer\n", 744 __func__); 745 JBUFFER_TRACE(jh, "oom!"); 746 error = -ENOMEM; 747 jbd_lock_bh_state(bh); 748 goto done; 749 } 750 goto repeat; 751 } 752 jh->b_frozen_data = frozen_buffer; 753 frozen_buffer = NULL; 754 need_copy = 1; 755 } 756 jh->b_next_transaction = transaction; 757 } 758 759 760 /* 761 * Finally, if the buffer is not journaled right now, we need to make 762 * sure it doesn't get written to disk before the caller actually 763 * commits the new data 764 */ 765 if (!jh->b_transaction) { 766 JBUFFER_TRACE(jh, "no transaction"); 767 J_ASSERT_JH(jh, !jh->b_next_transaction); 768 JBUFFER_TRACE(jh, "file as BJ_Reserved"); 769 spin_lock(&journal->j_list_lock); 770 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved); 771 spin_unlock(&journal->j_list_lock); 772 } 773 774done: 775 if (need_copy) { 776 struct page *page; 777 int offset; 778 char *source; 779 780 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)), 781 "Possible IO failure.\n"); 782 page = jh2bh(jh)->b_page; 783 offset = offset_in_page(jh2bh(jh)->b_data); 784 source = kmap_atomic(page, KM_USER0); 785 /* Fire data frozen trigger just before we copy the data */ 786 jbd2_buffer_frozen_trigger(jh, source + offset, 787 jh->b_triggers); 788 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size); 789 kunmap_atomic(source, KM_USER0); 790 791 /* 792 * Now that the frozen data is saved off, we need to store 793 * any matching triggers. 794 */ 795 jh->b_frozen_triggers = jh->b_triggers; 796 } 797 jbd_unlock_bh_state(bh); 798 799 /* 800 * If we are about to journal a buffer, then any revoke pending on it is 801 * no longer valid 802 */ 803 jbd2_journal_cancel_revoke(handle, jh); 804 805out: 806 if (unlikely(frozen_buffer)) /* It's usually NULL */ 807 jbd2_free(frozen_buffer, bh->b_size); 808 809 JBUFFER_TRACE(jh, "exit"); 810 return error; 811} 812 813/** 814 * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update. 815 * @handle: transaction to add buffer modifications to 816 * @bh: bh to be used for metadata writes 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 824int 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 */ 857int 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 /* first access by this transaction */ 899 jh->b_modified = 0; 900 901 JBUFFER_TRACE(jh, "file as BJ_Reserved"); 902 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved); 903 } else if (jh->b_transaction == journal->j_committing_transaction) { 904 /* first access by this transaction */ 905 jh->b_modified = 0; 906 907 JBUFFER_TRACE(jh, "set next transaction"); 908 jh->b_next_transaction = transaction; 909 } 910 spin_unlock(&journal->j_list_lock); 911 jbd_unlock_bh_state(bh); 912 913 /* 914 * akpm: I added this. ext3_alloc_branch can pick up new indirect 915 * blocks which contain freed but then revoked metadata. We need 916 * to cancel the revoke in case we end up freeing it yet again 917 * and the reallocating as data - this would cause a second revoke, 918 * which hits an assertion error. 919 */ 920 JBUFFER_TRACE(jh, "cancelling revoke"); 921 jbd2_journal_cancel_revoke(handle, jh); 922out: 923 jbd2_journal_put_journal_head(jh); 924 return err; 925} 926 927/** 928 * int jbd2_journal_get_undo_access() - Notify intent to modify metadata with 929 * non-rewindable consequences 930 * @handle: transaction 931 * @bh: buffer to undo 932 * 933 * Sometimes there is a need to distinguish between metadata which has 934 * been committed to disk and that which has not. The ext3fs code uses 935 * this for freeing and allocating space, we have to make sure that we 936 * do not reuse freed space until the deallocation has been committed, 937 * since if we overwrote that space we would make the delete 938 * un-rewindable in case of a crash. 939 * 940 * To deal with that, jbd2_journal_get_undo_access requests write access to a 941 * buffer for parts of non-rewindable operations such as delete 942 * operations on the bitmaps. The journaling code must keep a copy of 943 * the buffer's contents prior to the undo_access call until such time 944 * as we know that the buffer has definitely been committed to disk. 945 * 946 * We never need to know which transaction the committed data is part 947 * of, buffers touched here are guaranteed to be dirtied later and so 948 * will be committed to a new transaction in due course, at which point 949 * we can discard the old committed data pointer. 950 * 951 * Returns error number or 0 on success. 952 */ 953int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh) 954{ 955 int err; 956 struct journal_head *jh = jbd2_journal_add_journal_head(bh); 957 char *committed_data = NULL; 958 959 JBUFFER_TRACE(jh, "entry"); 960 961 /* 962 * Do this first --- it can drop the journal lock, so we want to 963 * make sure that obtaining the committed_data is done 964 * atomically wrt. completion of any outstanding commits. 965 */ 966 err = do_get_write_access(handle, jh, 1); 967 if (err) 968 goto out; 969 970repeat: 971 if (!jh->b_committed_data) { 972 committed_data = jbd2_alloc(jh2bh(jh)->b_size, GFP_NOFS); 973 if (!committed_data) { 974 printk(KERN_EMERG "%s: No memory for committed data\n", 975 __func__); 976 err = -ENOMEM; 977 goto out; 978 } 979 } 980 981 jbd_lock_bh_state(bh); 982 if (!jh->b_committed_data) { 983 /* Copy out the current buffer contents into the 984 * preserved, committed copy. */ 985 JBUFFER_TRACE(jh, "generate b_committed data"); 986 if (!committed_data) { 987 jbd_unlock_bh_state(bh); 988 goto repeat; 989 } 990 991 jh->b_committed_data = committed_data; 992 committed_data = NULL; 993 memcpy(jh->b_committed_data, bh->b_data, bh->b_size); 994 } 995 jbd_unlock_bh_state(bh); 996out: 997 jbd2_journal_put_journal_head(jh); 998 if (unlikely(committed_data)) 999 jbd2_free(committed_data, bh->b_size); 1000 return err; 1001} 1002 1003/** 1004 * void jbd2_journal_set_triggers() - Add triggers for commit writeout 1005 * @bh: buffer to trigger on 1006 * @type: struct jbd2_buffer_trigger_type containing the trigger(s). 1007 * 1008 * Set any triggers on this journal_head. This is always safe, because 1009 * triggers for a committing buffer will be saved off, and triggers for 1010 * a running transaction will match the buffer in that transaction. 1011 * 1012 * Call with NULL to clear the triggers. 1013 */ 1014void jbd2_journal_set_triggers(struct buffer_head *bh, 1015 struct jbd2_buffer_trigger_type *type) 1016{ 1017 struct journal_head *jh = bh2jh(bh); 1018 1019 jh->b_triggers = type; 1020} 1021 1022void jbd2_buffer_frozen_trigger(struct journal_head *jh, void *mapped_data, 1023 struct jbd2_buffer_trigger_type *triggers) 1024{ 1025 struct buffer_head *bh = jh2bh(jh); 1026 1027 if (!triggers || !triggers->t_frozen) 1028 return; 1029 1030 triggers->t_frozen(triggers, bh, mapped_data, bh->b_size); 1031} 1032 1033void jbd2_buffer_abort_trigger(struct journal_head *jh, 1034 struct jbd2_buffer_trigger_type *triggers) 1035{ 1036 if (!triggers || !triggers->t_abort) 1037 return; 1038 1039 triggers->t_abort(triggers, jh2bh(jh)); 1040} 1041 1042 1043 1044/** 1045 * int jbd2_journal_dirty_metadata() - mark a buffer as containing dirty metadata 1046 * @handle: transaction to add buffer to. 1047 * @bh: buffer to mark 1048 * 1049 * mark dirty metadata which needs to be journaled as part of the current 1050 * transaction. 1051 * 1052 * The buffer is placed on the transaction's metadata list and is marked 1053 * as belonging to the transaction. 1054 * 1055 * Returns error number or 0 on success. 1056 * 1057 * Special care needs to be taken if the buffer already belongs to the 1058 * current committing transaction (in which case we should have frozen 1059 * data present for that commit). In that case, we don't relink the 1060 * buffer: that only gets done when the old transaction finally 1061 * completes its commit. 1062 */ 1063int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh) 1064{ 1065 transaction_t *transaction = handle->h_transaction; 1066 journal_t *journal = transaction->t_journal; 1067 struct journal_head *jh = bh2jh(bh); 1068 1069 jbd_debug(5, "journal_head %p\n", jh); 1070 JBUFFER_TRACE(jh, "entry"); 1071 if (is_handle_aborted(handle)) 1072 goto out; 1073 1074 jbd_lock_bh_state(bh); 1075 1076 if (jh->b_modified == 0) { 1077 /* 1078 * This buffer's got modified and becoming part 1079 * of the transaction. This needs to be done 1080 * once a transaction -bzzz 1081 */ 1082 jh->b_modified = 1; 1083 J_ASSERT_JH(jh, handle->h_buffer_credits > 0); 1084 handle->h_buffer_credits--; 1085 } 1086 1087 /* 1088 * fastpath, to avoid expensive locking. If this buffer is already 1089 * on the running transaction's metadata list there is nothing to do. 1090 * Nobody can take it off again because there is a handle open. 1091 * I _think_ we're OK here with SMP barriers - a mistaken decision will 1092 * result in this test being false, so we go in and take the locks. 1093 */ 1094 if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) { 1095 JBUFFER_TRACE(jh, "fastpath"); 1096 J_ASSERT_JH(jh, jh->b_transaction == 1097 journal->j_running_transaction); 1098 goto out_unlock_bh; 1099 } 1100 1101 set_buffer_jbddirty(bh); 1102 1103 /* 1104 * Metadata already on the current transaction list doesn't 1105 * need to be filed. Metadata on another transaction's list must 1106 * be committing, and will be refiled once the commit completes: 1107 * leave it alone for now. 1108 */ 1109 if (jh->b_transaction != transaction) { 1110 JBUFFER_TRACE(jh, "already on other transaction"); 1111 J_ASSERT_JH(jh, jh->b_transaction == 1112 journal->j_committing_transaction); 1113 J_ASSERT_JH(jh, jh->b_next_transaction == transaction); 1114 /* And this case is illegal: we can't reuse another 1115 * transaction's data buffer, ever. */ 1116 goto out_unlock_bh; 1117 } 1118 1119 /* That test should have eliminated the following case: */ 1120 J_ASSERT_JH(jh, jh->b_frozen_data == NULL); 1121 1122 JBUFFER_TRACE(jh, "file as BJ_Metadata"); 1123 spin_lock(&journal->j_list_lock); 1124 __jbd2_journal_file_buffer(jh, handle->h_transaction, BJ_Metadata); 1125 spin_unlock(&journal->j_list_lock); 1126out_unlock_bh: 1127 jbd_unlock_bh_state(bh); 1128out: 1129 JBUFFER_TRACE(jh, "exit"); 1130 return 0; 1131} 1132 1133/* 1134 * jbd2_journal_release_buffer: undo a get_write_access without any buffer 1135 * updates, if the update decided in the end that it didn't need access. 1136 * 1137 */ 1138void 1139jbd2_journal_release_buffer(handle_t *handle, struct buffer_head *bh) 1140{ 1141 BUFFER_TRACE(bh, "entry"); 1142} 1143 1144/** 1145 * void jbd2_journal_forget() - bforget() for potentially-journaled buffers. 1146 * @handle: transaction handle 1147 * @bh: bh to 'forget' 1148 * 1149 * We can only do the bforget if there are no commits pending against the 1150 * buffer. If the buffer is dirty in the current running transaction we 1151 * can safely unlink it. 1152 * 1153 * bh may not be a journalled buffer at all - it may be a non-JBD 1154 * buffer which came off the hashtable. Check for this. 1155 * 1156 * Decrements bh->b_count by one. 1157 * 1158 * Allow this call even if the handle has aborted --- it may be part of 1159 * the caller's cleanup after an abort. 1160 */ 1161int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh) 1162{ 1163 transaction_t *transaction = handle->h_transaction; 1164 journal_t *journal = transaction->t_journal; 1165 struct journal_head *jh; 1166 int drop_reserve = 0; 1167 int err = 0; 1168 int was_modified = 0; 1169 1170 BUFFER_TRACE(bh, "entry"); 1171 1172 jbd_lock_bh_state(bh); 1173 spin_lock(&journal->j_list_lock); 1174 1175 if (!buffer_jbd(bh)) 1176 goto not_jbd; 1177 jh = bh2jh(bh); 1178 1179 /* Critical error: attempting to delete a bitmap buffer, maybe? 1180 * Don't do any jbd operations, and return an error. */ 1181 if (!J_EXPECT_JH(jh, !jh->b_committed_data, 1182 "inconsistent data on disk")) { 1183 err = -EIO; 1184 goto not_jbd; 1185 } 1186 1187 /* keep track of wether or not this transaction modified us */ 1188 was_modified = jh->b_modified; 1189 1190 /* 1191 * The buffer's going from the transaction, we must drop 1192 * all references -bzzz 1193 */ 1194 jh->b_modified = 0; 1195 1196 if (jh->b_transaction == handle->h_transaction) { 1197 J_ASSERT_JH(jh, !jh->b_frozen_data); 1198 1199 /* If we are forgetting a buffer which is already part 1200 * of this transaction, then we can just drop it from 1201 * the transaction immediately. */ 1202 clear_buffer_dirty(bh); 1203 clear_buffer_jbddirty(bh); 1204 1205 JBUFFER_TRACE(jh, "belongs to current transaction: unfile"); 1206 1207 /* 1208 * we only want to drop a reference if this transaction 1209 * modified the buffer 1210 */ 1211 if (was_modified) 1212 drop_reserve = 1; 1213 1214 /* 1215 * We are no longer going to journal this buffer. 1216 * However, the commit of this transaction is still 1217 * important to the buffer: the delete that we are now 1218 * processing might obsolete an old log entry, so by 1219 * committing, we can satisfy the buffer's checkpoint. 1220 * 1221 * So, if we have a checkpoint on the buffer, we should 1222 * now refile the buffer on our BJ_Forget list so that 1223 * we know to remove the checkpoint after we commit. 1224 */ 1225 1226 if (jh->b_cp_transaction) { 1227 __jbd2_journal_temp_unlink_buffer(jh); 1228 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget); 1229 } else { 1230 __jbd2_journal_unfile_buffer(jh); 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 1260not_jbd: 1261 spin_unlock(&journal->j_list_lock); 1262 jbd_unlock_bh_state(bh); 1263 __brelse(bh); 1264drop: 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 */ 1288int 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 committing 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 */ 1429int 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 1460static 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 1484static 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 */ 1507void __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/* 1554 * Remove buffer from all transactions. 1555 * 1556 * Called with bh_state lock and j_list_lock 1557 * 1558 * jh and bh may be already freed when this function returns. 1559 */ 1560static void __jbd2_journal_unfile_buffer(struct journal_head *jh) 1561{ 1562 __jbd2_journal_temp_unlink_buffer(jh); 1563 jh->b_transaction = NULL; 1564 jbd2_journal_put_journal_head(jh); 1565} 1566 1567void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh) 1568{ 1569 struct buffer_head *bh = jh2bh(jh); 1570 1571 /* Get reference so that buffer cannot be freed before we unlock it */ 1572 get_bh(bh); 1573 jbd_lock_bh_state(bh); 1574 spin_lock(&journal->j_list_lock); 1575 __jbd2_journal_unfile_buffer(jh); 1576 spin_unlock(&journal->j_list_lock); 1577 jbd_unlock_bh_state(bh); 1578 __brelse(bh); 1579} 1580 1581/* 1582 * Called from jbd2_journal_try_to_free_buffers(). 1583 * 1584 * Called under jbd_lock_bh_state(bh) 1585 */ 1586static void 1587__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh) 1588{ 1589 struct journal_head *jh; 1590 1591 jh = bh2jh(bh); 1592 1593 if (buffer_locked(bh) || buffer_dirty(bh)) 1594 goto out; 1595 1596 if (jh->b_next_transaction != NULL) 1597 goto out; 1598 1599 spin_lock(&journal->j_list_lock); 1600 if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) { 1601 /* written-back checkpointed metadata buffer */ 1602 if (jh->b_jlist == BJ_None) { 1603 JBUFFER_TRACE(jh, "remove from checkpoint list"); 1604 __jbd2_journal_remove_checkpoint(jh); 1605 } 1606 } 1607 spin_unlock(&journal->j_list_lock); 1608out: 1609 return; 1610} 1611 1612/** 1613 * int jbd2_journal_try_to_free_buffers() - try to free page buffers. 1614 * @journal: journal for operation 1615 * @page: to try and free 1616 * @gfp_mask: we use the mask to detect how hard should we try to release 1617 * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to 1618 * release the buffers. 1619 * 1620 * 1621 * For all the buffers on this page, 1622 * if they are fully written out ordered data, move them onto BUF_CLEAN 1623 * so try_to_free_buffers() can reap them. 1624 * 1625 * This function returns non-zero if we wish try_to_free_buffers() 1626 * to be called. We do this if the page is releasable by try_to_free_buffers(). 1627 * We also do it if the page has locked or dirty buffers and the caller wants 1628 * us to perform sync or async writeout. 1629 * 1630 * This complicates JBD locking somewhat. We aren't protected by the 1631 * BKL here. We wish to remove the buffer from its committing or 1632 * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer. 1633 * 1634 * This may *change* the value of transaction_t->t_datalist, so anyone 1635 * who looks at t_datalist needs to lock against this function. 1636 * 1637 * Even worse, someone may be doing a jbd2_journal_dirty_data on this 1638 * buffer. So we need to lock against that. jbd2_journal_dirty_data() 1639 * will come out of the lock with the buffer dirty, which makes it 1640 * ineligible for release here. 1641 * 1642 * Who else is affected by this? hmm... Really the only contender 1643 * is do_get_write_access() - it could be looking at the buffer while 1644 * journal_try_to_free_buffer() is changing its state. But that 1645 * cannot happen because we never reallocate freed data as metadata 1646 * while the data is part of a transaction. Yes? 1647 * 1648 * Return 0 on failure, 1 on success 1649 */ 1650int jbd2_journal_try_to_free_buffers(journal…
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