Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/cjb/mmc
[cris-mirror.git] / fs / jbd2 / transaction.c
blob1d1191050f99aaae5f0807149b47e699f29b12cf
1 /*
2 * linux/fs/jbd2/transaction.c
4 * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
6 * Copyright 1998 Red Hat corp --- All Rights Reserved
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.
12 * Generic filesystem transaction handling code; part of the ext2fs
13 * journaling system.
15 * This file manages transactions (compound commits managed by the
16 * journaling code) and handles (individual atomic operations by the
17 * filesystem).
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>
32 static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh);
35 * jbd2_get_transaction: obtain a new transaction_t object.
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).
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.
49 static transaction_t *
50 jbd2_get_transaction(journal_t *journal, transaction_t *transaction)
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);
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);
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;
73 return transaction;
77 * Handle management.
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.
85 * Update transiaction's maximum wait time, if debugging is enabled.
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.
94 static inline void update_t_max_wait(transaction_t *transaction)
96 #ifdef CONFIG_JBD2_DEBUG
97 unsigned long ts = jiffies;
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);
107 #endif
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.
117 static int start_this_handle(journal_t *journal, handle_t *handle,
118 int gfp_mask)
120 transaction_t *transaction, *new_transaction = NULL;
121 tid_t tid;
122 int needed, need_to_start;
123 int nblocks = handle->h_buffer_credits;
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;
132 alloc_transaction:
133 if (!journal->j_running_transaction) {
134 new_transaction = kzalloc(sizeof(*new_transaction), gfp_mask);
135 if (!new_transaction) {
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.
143 if ((gfp_mask & __GFP_FS) == 0) {
144 congestion_wait(BLK_RW_ASYNC, HZ/50);
145 goto alloc_transaction;
147 return -ENOMEM;
151 jbd_debug(3, "New handle %p going live.\n", handle);
154 * We need to hold j_state_lock until t_updates has been incremented,
155 * for proper journal barrier handling
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;
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;
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;
184 write_unlock(&journal->j_state_lock);
185 goto repeat;
188 transaction = journal->j_running_transaction;
191 * If the current transaction is locked down for commit, wait for the
192 * lock to be released.
194 if (transaction->t_state == T_LOCKED) {
195 DEFINE_WAIT(wait);
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;
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.
210 needed = atomic_add_return(nblocks,
211 &transaction->t_outstanding_credits);
213 if (needed > journal->j_max_transaction_buffers) {
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.
219 DEFINE_WAIT(wait);
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;
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.
242 * We must therefore ensure the necessary space in the journal
243 * *before* starting to dirty potentially checkpointed buffers
244 * in the new transaction.
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.
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().
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;
271 /* OK, account for the buffers that this operation expects to
272 * use and add the handle to the running transaction.
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);
284 lock_map_acquire(&handle->h_lockdep_map);
285 kfree(new_transaction);
286 return 0;
289 static struct lock_class_key jbd2_handle_key;
291 /* Allocate a new handle. This should probably be in a slab... */
292 static handle_t *new_handle(int nblocks)
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;
301 lockdep_init_map(&handle->h_lockdep_map, "jbd2_handle",
302 &jbd2_handle_key, 0);
304 return handle;
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
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.
316 * This function is visible to journal users (like ext3fs), so is not
317 * called with the journal already locked.
319 * Return a pointer to a newly allocated handle, or NULL on failure
321 handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int gfp_mask)
323 handle_t *handle = journal_current_handle();
324 int err;
326 if (!journal)
327 return ERR_PTR(-EROFS);
329 if (handle) {
330 J_ASSERT(handle->h_transaction->t_journal == journal);
331 handle->h_ref++;
332 return handle;
335 handle = new_handle(nblocks);
336 if (!handle)
337 return ERR_PTR(-ENOMEM);
339 current->journal_info = handle;
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);
347 return handle;
349 EXPORT_SYMBOL(jbd2__journal_start);
352 handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
354 return jbd2__journal_start(journal, nblocks, GFP_NOFS);
356 EXPORT_SYMBOL(jbd2_journal_start);
360 * int jbd2_journal_extend() - extend buffer credits.
361 * @handle: handle to 'extend'
362 * @nblocks: nr blocks to try to extend by.
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.
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.
374 * Return 0 on success, non-zero on failure.
376 * return code < 0 implies an error
377 * return code > 0 implies normal transaction-full status.
379 int jbd2_journal_extend(handle_t *handle, int nblocks)
381 transaction_t *transaction = handle->h_transaction;
382 journal_t *journal = transaction->t_journal;
383 int result;
384 int wanted;
386 result = -EIO;
387 if (is_handle_aborted(handle))
388 goto out;
390 result = 1;
392 read_lock(&journal->j_state_lock);
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;
401 spin_lock(&transaction->t_handle_lock);
402 wanted = atomic_read(&transaction->t_outstanding_credits) + nblocks;
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;
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;
416 handle->h_buffer_credits += nblocks;
417 atomic_add(nblocks, &transaction->t_outstanding_credits);
418 result = 0;
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;
431 * int jbd2_journal_restart() - restart a handle .
432 * @handle: handle to restart
433 * @nblocks: nr credits requested
435 * Restart a handle for a multi-transaction filesystem
436 * operation.
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.
444 int jbd2__journal_restart(handle_t *handle, int nblocks, int gfp_mask)
446 transaction_t *transaction = handle->h_transaction;
447 journal_t *journal = transaction->t_journal;
448 tid_t tid;
449 int need_to_start, ret;
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;
457 * First unlink the handle from its current transaction, and start the
458 * commit on that.
460 J_ASSERT(atomic_read(&transaction->t_updates) > 0);
461 J_ASSERT(journal_current_handle() == handle);
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);
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);
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;
483 EXPORT_SYMBOL(jbd2__journal_restart);
486 int jbd2_journal_restart(handle_t *handle, int nblocks)
488 return jbd2__journal_restart(handle, nblocks, GFP_NOFS);
490 EXPORT_SYMBOL(jbd2_journal_restart);
493 * void jbd2_journal_lock_updates () - establish a transaction barrier.
494 * @journal: Journal to establish a barrier on.
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.
500 * The journal lock should not be held on entry.
502 void jbd2_journal_lock_updates(journal_t *journal)
504 DEFINE_WAIT(wait);
506 write_lock(&journal->j_state_lock);
507 ++journal->j_barrier_count;
509 /* Wait until there are no running updates */
510 while (1) {
511 transaction_t *transaction = journal->j_running_transaction;
513 if (!transaction)
514 break;
516 spin_lock(&transaction->t_handle_lock);
517 if (!atomic_read(&transaction->t_updates)) {
518 spin_unlock(&transaction->t_handle_lock);
519 break;
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);
529 write_unlock(&journal->j_state_lock);
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.
537 mutex_lock(&journal->j_barrier);
541 * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier
542 * @journal: Journal to release the barrier on.
544 * Release a transaction barrier obtained with jbd2_journal_lock_updates().
546 * Should be called without the journal lock held.
548 void jbd2_journal_unlock_updates (journal_t *journal)
550 J_ASSERT(journal->j_barrier_count != 0);
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);
559 static void warn_dirty_buffer(struct buffer_head *bh)
561 char b[BDEVNAME_SIZE];
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);
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).
580 static int
581 do_get_write_access(handle_t *handle, struct journal_head *jh,
582 int force_copy)
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;
591 if (is_handle_aborted(handle))
592 return -EROFS;
594 transaction = handle->h_transaction;
595 journal = transaction->t_journal;
597 jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy);
599 JBUFFER_TRACE(jh, "entry");
600 repeat:
601 bh = jh2bh(jh);
603 /* @@@ Need to check for errors here at some point. */
605 lock_buffer(bh);
606 jbd_lock_bh_state(bh);
608 /* We now hold the buffer lock so it is safe to query the buffer
609 * state. Is the buffer dirty?
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.) */
621 if (buffer_dirty(bh)) {
623 * First question: is this buffer already part of the current
624 * transaction or the existing committing transaction?
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);
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.
641 JBUFFER_TRACE(jh, "Journalling dirty buffer");
642 clear_buffer_dirty(bh);
643 set_buffer_jbddirty(bh);
646 unlock_buffer(bh);
648 error = -EROFS;
649 if (is_handle_aborted(handle)) {
650 jbd_unlock_bh_state(bh);
651 goto out;
653 error = 0;
656 * The buffer is already part of this transaction if b_transaction or
657 * b_next_transaction points to it
659 if (jh->b_transaction == transaction ||
660 jh->b_next_transaction == transaction)
661 goto done;
664 * this is the first time this transaction is touching this buffer,
665 * reset the modified flag
667 jh->b_modified = 0;
670 * If there is already a copy-out version of this buffer, then we don't
671 * need to make another one
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;
680 /* Is there data here we need to preserve? */
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);
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. */
697 if (jh->b_jlist == BJ_Shadow) {
698 DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
699 wait_queue_head_t *wqh;
701 wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
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();
713 finish_wait(wqh, &wait.wait);
714 goto repeat;
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.
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. */
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;
748 goto repeat;
750 jh->b_frozen_data = frozen_buffer;
751 frozen_buffer = NULL;
752 need_copy = 1;
754 jh->b_next_transaction = transaction;
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
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);
773 done:
774 if (need_copy) {
775 struct page *page;
776 int offset;
777 char *source;
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);
791 * Now that the frozen data is saved off, we need to store
792 * any matching triggers.
794 jh->b_frozen_triggers = jh->b_triggers;
796 jbd_unlock_bh_state(bh);
799 * If we are about to journal a buffer, then any revoke pending on it is
800 * no longer valid
802 jbd2_journal_cancel_revoke(handle, jh);
804 out:
805 if (unlikely(frozen_buffer)) /* It's usually NULL */
806 jbd2_free(frozen_buffer, bh->b_size);
808 JBUFFER_TRACE(jh, "exit");
809 return error;
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
818 * Returns an error code or 0 on success.
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.
824 int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
826 struct journal_head *jh = jbd2_journal_add_journal_head(bh);
827 int rc;
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;
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.
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. */
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.
855 * Call this if you create a new bh.
857 int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
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;
864 jbd_debug(5, "journal_head %p\n", jh);
865 err = -EROFS;
866 if (is_handle_aborted(handle))
867 goto out;
868 err = 0;
870 JBUFFER_TRACE(jh, "entry");
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.
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)));
885 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
886 J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
888 if (jh->b_transaction == NULL) {
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.
897 clear_buffer_dirty(jh2bh(jh));
898 jh->b_transaction = transaction;
900 /* first access by this transaction */
901 jh->b_modified = 0;
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;
909 JBUFFER_TRACE(jh, "set next transaction");
910 jh->b_next_transaction = transaction;
912 spin_unlock(&journal->j_list_lock);
913 jbd_unlock_bh_state(bh);
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.
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;
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)
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.
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.
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.
954 * Returns error number or 0 on success.
956 int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
958 int err;
959 struct journal_head *jh = jbd2_journal_add_journal_head(bh);
960 char *committed_data = NULL;
962 JBUFFER_TRACE(jh, "entry");
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.
969 err = do_get_write_access(handle, jh, 1);
970 if (err)
971 goto out;
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;
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;
994 jh->b_committed_data = committed_data;
995 committed_data = NULL;
996 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
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;
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).
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.
1015 * Call with NULL to clear the triggers.
1017 void jbd2_journal_set_triggers(struct buffer_head *bh,
1018 struct jbd2_buffer_trigger_type *type)
1020 struct journal_head *jh = bh2jh(bh);
1022 jh->b_triggers = type;
1025 void jbd2_buffer_frozen_trigger(struct journal_head *jh, void *mapped_data,
1026 struct jbd2_buffer_trigger_type *triggers)
1028 struct buffer_head *bh = jh2bh(jh);
1030 if (!triggers || !triggers->t_frozen)
1031 return;
1033 triggers->t_frozen(triggers, bh, mapped_data, bh->b_size);
1036 void jbd2_buffer_abort_trigger(struct journal_head *jh,
1037 struct jbd2_buffer_trigger_type *triggers)
1039 if (!triggers || !triggers->t_abort)
1040 return;
1042 triggers->t_abort(triggers, jh2bh(jh));
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
1052 * mark dirty metadata which needs to be journaled as part of the current
1053 * transaction.
1055 * The buffer is placed on the transaction's metadata list and is marked
1056 * as belonging to the transaction.
1058 * Returns error number or 0 on success.
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.
1066 int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1068 transaction_t *transaction = handle->h_transaction;
1069 journal_t *journal = transaction->t_journal;
1070 struct journal_head *jh = bh2jh(bh);
1072 jbd_debug(5, "journal_head %p\n", jh);
1073 JBUFFER_TRACE(jh, "entry");
1074 if (is_handle_aborted(handle))
1075 goto out;
1077 jbd_lock_bh_state(bh);
1079 if (jh->b_modified == 0) {
1081 * This buffer's got modified and becoming part
1082 * of the transaction. This needs to be done
1083 * once a transaction -bzzz
1085 jh->b_modified = 1;
1086 J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
1087 handle->h_buffer_credits--;
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.
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;
1104 set_buffer_jbddirty(bh);
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.
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;
1122 /* That test should have eliminated the following case: */
1123 J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
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;
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.
1141 void
1142 jbd2_journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1144 BUFFER_TRACE(bh, "entry");
1148 * void jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1149 * @handle: transaction handle
1150 * @bh: bh to 'forget'
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.
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.
1159 * Decrements bh->b_count by one.
1161 * Allow this call even if the handle has aborted --- it may be part of
1162 * the caller's cleanup after an abort.
1164 int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh)
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;
1173 BUFFER_TRACE(bh, "entry");
1175 jbd_lock_bh_state(bh);
1176 spin_lock(&journal->j_list_lock);
1178 if (!buffer_jbd(bh))
1179 goto not_jbd;
1180 jh = bh2jh(bh);
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;
1190 /* keep track of wether or not this transaction modified us */
1191 was_modified = jh->b_modified;
1194 * The buffer's going from the transaction, we must drop
1195 * all references -bzzz
1197 jh->b_modified = 0;
1199 if (jh->b_transaction == handle->h_transaction) {
1200 J_ASSERT_JH(jh, !jh->b_frozen_data);
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);
1208 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1211 * we only want to drop a reference if this transaction
1212 * modified the buffer
1214 if (was_modified)
1215 drop_reserve = 1;
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.
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.
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;
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. */
1252 if (jh->b_next_transaction) {
1253 J_ASSERT(jh->b_next_transaction == transaction);
1254 jh->b_next_transaction = NULL;
1257 * only drop a reference if this transaction modified
1258 * the buffer
1260 if (was_modified)
1261 drop_reserve = 1;
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++;
1274 return err;
1278 * int jbd2_journal_stop() - complete a transaction
1279 * @handle: tranaction to complete.
1281 * All done for a particular handle.
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.
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.
1293 int jbd2_journal_stop(handle_t *handle)
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;
1301 J_ASSERT(journal_current_handle() == handle);
1303 if (is_handle_aborted(handle))
1304 err = -EIO;
1305 else {
1306 J_ASSERT(atomic_read(&transaction->t_updates) > 0);
1307 err = 0;
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;
1316 jbd_debug(4, "Handle %p going down\n", handle);
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...
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.
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.
1345 pid = current->pid;
1346 if (handle->h_sync && journal->j_last_sync_writer != pid) {
1347 u64 commit_time, trans_time;
1349 journal->j_last_sync_writer = pid;
1351 read_lock(&journal->j_state_lock);
1352 commit_time = journal->j_average_commit_time;
1353 read_unlock(&journal->j_state_lock);
1355 trans_time = ktime_to_ns(ktime_sub(ktime_get(),
1356 transaction->t_start_time));
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);
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);
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);
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.
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. */
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);
1397 * Special case: JBD2_SYNC synchronous updates require us
1398 * to wait for the commit to complete.
1400 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1401 wait_for_commit = 1;
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.
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);
1417 if (wait_for_commit)
1418 err = jbd2_log_wait_commit(journal, tid);
1420 lock_map_release(&handle->h_lockdep_map);
1422 jbd2_free_handle(handle);
1423 return err;
1427 * int jbd2_journal_force_commit() - force any uncommitted transactions
1428 * @journal: journal to force
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.
1434 int jbd2_journal_force_commit(journal_t *journal)
1436 handle_t *handle;
1437 int ret;
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);
1446 return ret;
1451 * List management code snippets: various functions for manipulating the
1452 * transaction buffer lists.
1457 * Append a buffer to a transaction list, given the transaction's list head
1458 * pointer.
1460 * j_list_lock is held.
1462 * jbd_lock_bh_state(jh2bh(jh)) is held.
1465 static inline void
1466 __blist_add_buffer(struct journal_head **list, struct journal_head *jh)
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;
1481 * Remove a buffer from a transaction list, given the transaction's list
1482 * head pointer.
1484 * Called with j_list_lock held, and the journal may not be locked.
1486 * jbd_lock_bh_state(jh2bh(jh)) is held.
1489 static inline void
1490 __blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1492 if (*list == jh) {
1493 *list = jh->b_tnext;
1494 if (*list == jh)
1495 *list = NULL;
1497 jh->b_tprev->b_tnext = jh->b_tnext;
1498 jh->b_tnext->b_tprev = jh->b_tprev;
1502 * Remove a buffer from the appropriate transaction list.
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.
1510 * Called under j_list_lock. The journal may not be locked.
1512 void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
1514 struct journal_head **list = NULL;
1515 transaction_t *transaction;
1516 struct buffer_head *bh = jh2bh(jh);
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);
1523 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1524 if (jh->b_jlist != BJ_None)
1525 J_ASSERT_JH(jh, transaction != NULL);
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;
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 */
1558 void __jbd2_journal_unfile_buffer(struct journal_head *jh)
1560 __jbd2_journal_temp_unlink_buffer(jh);
1561 jh->b_transaction = NULL;
1564 void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
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));
1574 * Called from jbd2_journal_try_to_free_buffers().
1576 * Called under jbd_lock_bh_state(bh)
1578 static void
1579 __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1581 struct journal_head *jh;
1583 jh = bh2jh(bh);
1585 if (buffer_locked(bh) || buffer_dirty(bh))
1586 goto out;
1588 if (jh->b_next_transaction != NULL)
1589 goto out;
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);
1601 spin_unlock(&journal->j_list_lock);
1602 out:
1603 return;
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.
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.
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.
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.
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.
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.
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?
1642 * Return 0 on failure, 1 on success
1644 int jbd2_journal_try_to_free_buffers(journal_t *journal,
1645 struct page *page, gfp_t gfp_mask)
1647 struct buffer_head *head;
1648 struct buffer_head *bh;
1649 int ret = 0;
1651 J_ASSERT(PageLocked(page));
1653 head = page_buffers(page);
1654 bh = head;
1655 do {
1656 struct journal_head *jh;
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().
1664 jh = jbd2_journal_grab_journal_head(bh);
1665 if (!jh)
1666 continue;
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);
1676 ret = try_to_free_buffers(page);
1678 busy:
1679 return ret;
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.
1690 * Called under j_list_lock.
1692 * Called under jbd_lock_bh_state(bh).
1694 static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1696 int may_free = 1;
1697 struct buffer_head *bh = jh2bh(jh);
1699 __jbd2_journal_unfile_buffer(jh);
1701 if (jh->b_cp_transaction) {
1702 JBUFFER_TRACE(jh, "on running+cp transaction");
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
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);
1716 return may_free;
1720 * jbd2_journal_invalidatepage
1722 * This code is tricky. It has a number of cases to deal with.
1724 * There are two invariants which this code relies on:
1726 * i_size must be updated on disk before we start calling invalidatepage on the
1727 * data.
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.
1735 * Note however that we can *not* throw away data belonging to the
1736 * previous, committing transaction!
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
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.
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
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.
1763 * We're outside-transaction here. Either or both of j_running_transaction
1764 * and j_committing_transaction may be NULL.
1766 static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1768 transaction_t *transaction;
1769 struct journal_head *jh;
1770 int may_free = 1;
1771 int ret;
1773 BUFFER_TRACE(bh, "entry");
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
1781 if (!buffer_jbd(bh))
1782 goto zap_buffer_unlocked;
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);
1789 jh = jbd2_journal_grab_journal_head(bh);
1790 if (!jh)
1791 goto zap_buffer_no_jh;
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.
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;
1819 if (!buffer_dirty(bh)) {
1820 /* bdflush has written it. We can drop it now */
1821 goto zap_buffer;
1824 /* OK, it must be in the journal but still not
1825 * written fully to disk: it's metadata or
1826 * journaled data... */
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;
1861 } else if (transaction == journal->j_committing_transaction) {
1862 JBUFFER_TRACE(jh, "on committing transaction");
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.
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);
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;
1907 * void jbd2_journal_invalidatepage()
1908 * @journal: journal to use for flush...
1909 * @page: page to flush
1910 * @offset: length of page to invalidate.
1912 * Reap page buffers containing data after offset in page.
1915 void jbd2_journal_invalidatepage(journal_t *journal,
1916 struct page *page,
1917 unsigned long offset)
1919 struct buffer_head *head, *bh, *next;
1920 unsigned int curr_off = 0;
1921 int may_free = 1;
1923 if (!PageLocked(page))
1924 BUG();
1925 if (!page_has_buffers(page))
1926 return;
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. */
1932 head = bh = page_buffers(page);
1933 do {
1934 unsigned int next_off = curr_off + bh->b_size;
1935 next = bh->b_this_page;
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);
1943 curr_off = next_off;
1944 bh = next;
1946 } while (bh != head);
1948 if (!offset) {
1949 if (may_free && try_to_free_buffers(page))
1950 J_ASSERT(!page_has_buffers(page));
1955 * File a buffer on the given transaction list.
1957 void __jbd2_journal_file_buffer(struct journal_head *jh,
1958 transaction_t *transaction, int jlist)
1960 struct journal_head **list = NULL;
1961 int was_dirty = 0;
1962 struct buffer_head *bh = jh2bh(jh);
1964 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1965 assert_spin_locked(&transaction->t_journal->j_list_lock);
1967 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1968 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
1969 jh->b_transaction == NULL);
1971 if (jh->b_transaction && jh->b_jlist == jlist)
1972 return;
1974 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
1975 jlist == BJ_Shadow || jlist == BJ_Forget) {
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.
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;
1990 if (jh->b_transaction)
1991 __jbd2_journal_temp_unlink_buffer(jh);
1992 jh->b_transaction = transaction;
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;
2020 __blist_add_buffer(list, jh);
2021 jh->b_jlist = jlist;
2023 if (was_dirty)
2024 set_buffer_jbddirty(bh);
2027 void jbd2_journal_file_buffer(struct journal_head *jh,
2028 transaction_t *transaction, int jlist)
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));
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.
2043 * Called under journal->j_list_lock
2045 * Called under jbd_lock_bh_state(jh2bh(jh))
2047 void __jbd2_journal_refile_buffer(struct journal_head *jh)
2049 int was_dirty, jlist;
2050 struct buffer_head *bh = jh2bh(jh);
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);
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;
2063 * It has been modified by a later transaction: add it to the new
2064 * transaction's metadata list.
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);
2080 if (was_dirty)
2081 set_buffer_jbddirty(bh);
2085 * For the unlocked version of this call, also make sure that any
2086 * hanging journal_head is cleaned up if necessary.
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.
2096 * *** The journal_head may be freed by this call! ***
2098 void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2100 struct buffer_head *bh = jh2bh(jh);
2102 jbd_lock_bh_state(bh);
2103 spin_lock(&journal->j_list_lock);
2105 __jbd2_journal_refile_buffer(jh);
2106 jbd_unlock_bh_state(bh);
2107 jbd2_journal_remove_journal_head(bh);
2109 spin_unlock(&journal->j_list_lock);
2110 __brelse(bh);
2114 * File inode in the inode list of the handle's transaction
2116 int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode)
2118 transaction_t *transaction = handle->h_transaction;
2119 journal_t *journal = transaction->t_journal;
2121 if (is_handle_aborted(handle))
2122 return -EIO;
2124 jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode->i_vfs_inode->i_ino,
2125 transaction->t_tid);
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.
2140 if (jinode->i_transaction == transaction ||
2141 jinode->i_next_transaction == transaction)
2142 return 0;
2144 spin_lock(&journal->j_list_lock);
2146 if (jinode->i_transaction == transaction ||
2147 jinode->i_next_transaction == transaction)
2148 goto done;
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;
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);
2166 return 0;
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.
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).
2189 int jbd2_journal_begin_ordered_truncate(journal_t *journal,
2190 struct jbd2_inode *jinode,
2191 loff_t new_size)
2193 transaction_t *inode_trans, *commit_trans;
2194 int ret = 0;
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);
2214 out:
2215 return ret;