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
15 * This file manages transactions (compound commits managed by the
16 * journaling code) and handles (individual atomic operations by the
20 #include <linux/time.h>
22 #include <linux/jbd2.h>
23 #include <linux/errno.h>
24 #include <linux/slab.h>
25 #include <linux/timer.h>
27 #include <linux/highmem.h>
28 #include <linux/hrtimer.h>
29 #include <linux/backing-dev.h>
30 #include <linux/bug.h>
31 #include <linux/module.h>
33 #include <trace/events/jbd2.h>
35 static void __jbd2_journal_temp_unlink_buffer(struct journal_head
*jh
);
36 static void __jbd2_journal_unfile_buffer(struct journal_head
*jh
);
38 static struct kmem_cache
*transaction_cache
;
39 int __init
jbd2_journal_init_transaction_cache(void)
41 J_ASSERT(!transaction_cache
);
42 transaction_cache
= kmem_cache_create("jbd2_transaction_s",
43 sizeof(transaction_t
),
45 SLAB_HWCACHE_ALIGN
|SLAB_TEMPORARY
,
47 if (transaction_cache
)
52 void jbd2_journal_destroy_transaction_cache(void)
54 if (transaction_cache
) {
55 kmem_cache_destroy(transaction_cache
);
56 transaction_cache
= NULL
;
60 void jbd2_journal_free_transaction(transaction_t
*transaction
)
62 if (unlikely(ZERO_OR_NULL_PTR(transaction
)))
64 kmem_cache_free(transaction_cache
, transaction
);
68 * jbd2_get_transaction: obtain a new transaction_t object.
70 * Simply allocate and initialise a new transaction. Create it in
71 * RUNNING state and add it to the current journal (which should not
72 * have an existing running transaction: we only make a new transaction
73 * once we have started to commit the old one).
76 * The journal MUST be locked. We don't perform atomic mallocs on the
77 * new transaction and we can't block without protecting against other
78 * processes trying to touch the journal while it is in transition.
82 static transaction_t
*
83 jbd2_get_transaction(journal_t
*journal
, transaction_t
*transaction
)
85 transaction
->t_journal
= journal
;
86 transaction
->t_state
= T_RUNNING
;
87 transaction
->t_start_time
= ktime_get();
88 transaction
->t_tid
= journal
->j_transaction_sequence
++;
89 transaction
->t_expires
= jiffies
+ journal
->j_commit_interval
;
90 spin_lock_init(&transaction
->t_handle_lock
);
91 atomic_set(&transaction
->t_updates
, 0);
92 atomic_set(&transaction
->t_outstanding_credits
, 0);
93 atomic_set(&transaction
->t_handle_count
, 0);
94 INIT_LIST_HEAD(&transaction
->t_inode_list
);
95 INIT_LIST_HEAD(&transaction
->t_private_list
);
97 /* Set up the commit timer for the new transaction. */
98 journal
->j_commit_timer
.expires
= round_jiffies_up(transaction
->t_expires
);
99 add_timer(&journal
->j_commit_timer
);
101 J_ASSERT(journal
->j_running_transaction
== NULL
);
102 journal
->j_running_transaction
= transaction
;
103 transaction
->t_max_wait
= 0;
104 transaction
->t_start
= jiffies
;
105 transaction
->t_requested
= 0;
113 * A handle_t is an object which represents a single atomic update to a
114 * filesystem, and which tracks all of the modifications which form part
115 * of that one update.
119 * Update transaction's maximum wait time, if debugging is enabled.
121 * In order for t_max_wait to be reliable, it must be protected by a
122 * lock. But doing so will mean that start_this_handle() can not be
123 * run in parallel on SMP systems, which limits our scalability. So
124 * unless debugging is enabled, we no longer update t_max_wait, which
125 * means that maximum wait time reported by the jbd2_run_stats
126 * tracepoint will always be zero.
128 static inline void update_t_max_wait(transaction_t
*transaction
,
131 #ifdef CONFIG_JBD2_DEBUG
132 if (jbd2_journal_enable_debug
&&
133 time_after(transaction
->t_start
, ts
)) {
134 ts
= jbd2_time_diff(ts
, transaction
->t_start
);
135 spin_lock(&transaction
->t_handle_lock
);
136 if (ts
> transaction
->t_max_wait
)
137 transaction
->t_max_wait
= ts
;
138 spin_unlock(&transaction
->t_handle_lock
);
144 * start_this_handle: Given a handle, deal with any locking or stalling
145 * needed to make sure that there is enough journal space for the handle
146 * to begin. Attach the handle to a transaction and set up the
147 * transaction's buffer credits.
150 static int start_this_handle(journal_t
*journal
, handle_t
*handle
,
153 transaction_t
*transaction
, *new_transaction
= NULL
;
155 int needed
, need_to_start
;
156 int nblocks
= handle
->h_buffer_credits
;
157 unsigned long ts
= jiffies
;
159 if (nblocks
> journal
->j_max_transaction_buffers
) {
160 printk(KERN_ERR
"JBD2: %s wants too many credits (%d > %d)\n",
161 current
->comm
, nblocks
,
162 journal
->j_max_transaction_buffers
);
167 if (!journal
->j_running_transaction
) {
168 new_transaction
= kmem_cache_zalloc(transaction_cache
,
170 if (!new_transaction
) {
172 * If __GFP_FS is not present, then we may be
173 * being called from inside the fs writeback
174 * layer, so we MUST NOT fail. Since
175 * __GFP_NOFAIL is going away, we will arrange
176 * to retry the allocation ourselves.
178 if ((gfp_mask
& __GFP_FS
) == 0) {
179 congestion_wait(BLK_RW_ASYNC
, HZ
/50);
180 goto alloc_transaction
;
186 jbd_debug(3, "New handle %p going live.\n", handle
);
189 * We need to hold j_state_lock until t_updates has been incremented,
190 * for proper journal barrier handling
193 read_lock(&journal
->j_state_lock
);
194 BUG_ON(journal
->j_flags
& JBD2_UNMOUNT
);
195 if (is_journal_aborted(journal
) ||
196 (journal
->j_errno
!= 0 && !(journal
->j_flags
& JBD2_ACK_ERR
))) {
197 read_unlock(&journal
->j_state_lock
);
198 jbd2_journal_free_transaction(new_transaction
);
202 /* Wait on the journal's transaction barrier if necessary */
203 if (journal
->j_barrier_count
) {
204 read_unlock(&journal
->j_state_lock
);
205 wait_event(journal
->j_wait_transaction_locked
,
206 journal
->j_barrier_count
== 0);
210 if (!journal
->j_running_transaction
) {
211 read_unlock(&journal
->j_state_lock
);
212 if (!new_transaction
)
213 goto alloc_transaction
;
214 write_lock(&journal
->j_state_lock
);
215 if (!journal
->j_running_transaction
&&
216 !journal
->j_barrier_count
) {
217 jbd2_get_transaction(journal
, new_transaction
);
218 new_transaction
= NULL
;
220 write_unlock(&journal
->j_state_lock
);
224 transaction
= journal
->j_running_transaction
;
227 * If the current transaction is locked down for commit, wait for the
228 * lock to be released.
230 if (transaction
->t_state
== T_LOCKED
) {
233 prepare_to_wait(&journal
->j_wait_transaction_locked
,
234 &wait
, TASK_UNINTERRUPTIBLE
);
235 read_unlock(&journal
->j_state_lock
);
237 finish_wait(&journal
->j_wait_transaction_locked
, &wait
);
242 * If there is not enough space left in the log to write all potential
243 * buffers requested by this operation, we need to stall pending a log
244 * checkpoint to free some more log space.
246 needed
= atomic_add_return(nblocks
,
247 &transaction
->t_outstanding_credits
);
249 if (needed
> journal
->j_max_transaction_buffers
) {
251 * If the current transaction is already too large, then start
252 * to commit it: we can then go back and attach this handle to
257 jbd_debug(2, "Handle %p starting new commit...\n", handle
);
258 atomic_sub(nblocks
, &transaction
->t_outstanding_credits
);
259 prepare_to_wait(&journal
->j_wait_transaction_locked
, &wait
,
260 TASK_UNINTERRUPTIBLE
);
261 tid
= transaction
->t_tid
;
262 need_to_start
= !tid_geq(journal
->j_commit_request
, tid
);
263 read_unlock(&journal
->j_state_lock
);
265 jbd2_log_start_commit(journal
, tid
);
267 finish_wait(&journal
->j_wait_transaction_locked
, &wait
);
272 * The commit code assumes that it can get enough log space
273 * without forcing a checkpoint. This is *critical* for
274 * correctness: a checkpoint of a buffer which is also
275 * associated with a committing transaction creates a deadlock,
276 * so commit simply cannot force through checkpoints.
278 * We must therefore ensure the necessary space in the journal
279 * *before* starting to dirty potentially checkpointed buffers
280 * in the new transaction.
282 * The worst part is, any transaction currently committing can
283 * reduce the free space arbitrarily. Be careful to account for
284 * those buffers when checkpointing.
288 * @@@ AKPM: This seems rather over-defensive. We're giving commit
289 * a _lot_ of headroom: 1/4 of the journal plus the size of
290 * the committing transaction. Really, we only need to give it
291 * committing_transaction->t_outstanding_credits plus "enough" for
292 * the log control blocks.
293 * Also, this test is inconsistent with the matching one in
294 * jbd2_journal_extend().
296 if (__jbd2_log_space_left(journal
) < jbd_space_needed(journal
)) {
297 jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle
);
298 atomic_sub(nblocks
, &transaction
->t_outstanding_credits
);
299 read_unlock(&journal
->j_state_lock
);
300 write_lock(&journal
->j_state_lock
);
301 if (__jbd2_log_space_left(journal
) < jbd_space_needed(journal
))
302 __jbd2_log_wait_for_space(journal
);
303 write_unlock(&journal
->j_state_lock
);
307 /* OK, account for the buffers that this operation expects to
308 * use and add the handle to the running transaction.
310 update_t_max_wait(transaction
, ts
);
311 handle
->h_transaction
= transaction
;
312 handle
->h_requested_credits
= nblocks
;
313 handle
->h_start_jiffies
= jiffies
;
314 atomic_inc(&transaction
->t_updates
);
315 atomic_inc(&transaction
->t_handle_count
);
316 jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
318 atomic_read(&transaction
->t_outstanding_credits
),
319 __jbd2_log_space_left(journal
));
320 read_unlock(&journal
->j_state_lock
);
322 lock_map_acquire(&handle
->h_lockdep_map
);
323 jbd2_journal_free_transaction(new_transaction
);
327 static struct lock_class_key jbd2_handle_key
;
329 /* Allocate a new handle. This should probably be in a slab... */
330 static handle_t
*new_handle(int nblocks
)
332 handle_t
*handle
= jbd2_alloc_handle(GFP_NOFS
);
335 handle
->h_buffer_credits
= nblocks
;
338 lockdep_init_map(&handle
->h_lockdep_map
, "jbd2_handle",
339 &jbd2_handle_key
, 0);
345 * handle_t *jbd2_journal_start() - Obtain a new handle.
346 * @journal: Journal to start transaction on.
347 * @nblocks: number of block buffer we might modify
349 * We make sure that the transaction can guarantee at least nblocks of
350 * modified buffers in the log. We block until the log can guarantee
353 * This function is visible to journal users (like ext3fs), so is not
354 * called with the journal already locked.
356 * Return a pointer to a newly allocated handle, or an ERR_PTR() value
359 handle_t
*jbd2__journal_start(journal_t
*journal
, int nblocks
, gfp_t gfp_mask
,
360 unsigned int type
, unsigned int line_no
)
362 handle_t
*handle
= journal_current_handle();
366 return ERR_PTR(-EROFS
);
369 J_ASSERT(handle
->h_transaction
->t_journal
== journal
);
374 handle
= new_handle(nblocks
);
376 return ERR_PTR(-ENOMEM
);
378 current
->journal_info
= handle
;
380 err
= start_this_handle(journal
, handle
, gfp_mask
);
382 jbd2_free_handle(handle
);
383 current
->journal_info
= NULL
;
386 handle
->h_type
= type
;
387 handle
->h_line_no
= line_no
;
388 trace_jbd2_handle_start(journal
->j_fs_dev
->bd_dev
,
389 handle
->h_transaction
->t_tid
, type
,
393 EXPORT_SYMBOL(jbd2__journal_start
);
396 handle_t
*jbd2_journal_start(journal_t
*journal
, int nblocks
)
398 return jbd2__journal_start(journal
, nblocks
, GFP_NOFS
, 0, 0);
400 EXPORT_SYMBOL(jbd2_journal_start
);
404 * int jbd2_journal_extend() - extend buffer credits.
405 * @handle: handle to 'extend'
406 * @nblocks: nr blocks to try to extend by.
408 * Some transactions, such as large extends and truncates, can be done
409 * atomically all at once or in several stages. The operation requests
410 * a credit for a number of buffer modications in advance, but can
411 * extend its credit if it needs more.
413 * jbd2_journal_extend tries to give the running handle more buffer credits.
414 * It does not guarantee that allocation - this is a best-effort only.
415 * The calling process MUST be able to deal cleanly with a failure to
418 * Return 0 on success, non-zero on failure.
420 * return code < 0 implies an error
421 * return code > 0 implies normal transaction-full status.
423 int jbd2_journal_extend(handle_t
*handle
, int nblocks
)
425 transaction_t
*transaction
= handle
->h_transaction
;
426 journal_t
*journal
= transaction
->t_journal
;
431 if (is_handle_aborted(handle
))
436 read_lock(&journal
->j_state_lock
);
438 /* Don't extend a locked-down transaction! */
439 if (handle
->h_transaction
->t_state
!= T_RUNNING
) {
440 jbd_debug(3, "denied handle %p %d blocks: "
441 "transaction not running\n", handle
, nblocks
);
445 spin_lock(&transaction
->t_handle_lock
);
446 wanted
= atomic_read(&transaction
->t_outstanding_credits
) + nblocks
;
448 if (wanted
> journal
->j_max_transaction_buffers
) {
449 jbd_debug(3, "denied handle %p %d blocks: "
450 "transaction too large\n", handle
, nblocks
);
454 if (wanted
> __jbd2_log_space_left(journal
)) {
455 jbd_debug(3, "denied handle %p %d blocks: "
456 "insufficient log space\n", handle
, nblocks
);
460 trace_jbd2_handle_extend(journal
->j_fs_dev
->bd_dev
,
461 handle
->h_transaction
->t_tid
,
462 handle
->h_type
, handle
->h_line_no
,
463 handle
->h_buffer_credits
,
466 handle
->h_buffer_credits
+= nblocks
;
467 handle
->h_requested_credits
+= nblocks
;
468 atomic_add(nblocks
, &transaction
->t_outstanding_credits
);
471 jbd_debug(3, "extended handle %p by %d\n", handle
, nblocks
);
473 spin_unlock(&transaction
->t_handle_lock
);
475 read_unlock(&journal
->j_state_lock
);
482 * int jbd2_journal_restart() - restart a handle .
483 * @handle: handle to restart
484 * @nblocks: nr credits requested
486 * Restart a handle for a multi-transaction filesystem
489 * If the jbd2_journal_extend() call above fails to grant new buffer credits
490 * to a running handle, a call to jbd2_journal_restart will commit the
491 * handle's transaction so far and reattach the handle to a new
492 * transaction capabable of guaranteeing the requested number of
495 int jbd2__journal_restart(handle_t
*handle
, int nblocks
, gfp_t gfp_mask
)
497 transaction_t
*transaction
= handle
->h_transaction
;
498 journal_t
*journal
= transaction
->t_journal
;
500 int need_to_start
, ret
;
502 /* If we've had an abort of any type, don't even think about
503 * actually doing the restart! */
504 if (is_handle_aborted(handle
))
508 * First unlink the handle from its current transaction, and start the
511 J_ASSERT(atomic_read(&transaction
->t_updates
) > 0);
512 J_ASSERT(journal_current_handle() == handle
);
514 read_lock(&journal
->j_state_lock
);
515 spin_lock(&transaction
->t_handle_lock
);
516 atomic_sub(handle
->h_buffer_credits
,
517 &transaction
->t_outstanding_credits
);
518 if (atomic_dec_and_test(&transaction
->t_updates
))
519 wake_up(&journal
->j_wait_updates
);
520 tid
= transaction
->t_tid
;
521 spin_unlock(&transaction
->t_handle_lock
);
523 jbd_debug(2, "restarting handle %p\n", handle
);
524 need_to_start
= !tid_geq(journal
->j_commit_request
, tid
);
525 read_unlock(&journal
->j_state_lock
);
527 jbd2_log_start_commit(journal
, tid
);
529 lock_map_release(&handle
->h_lockdep_map
);
530 handle
->h_buffer_credits
= nblocks
;
531 ret
= start_this_handle(journal
, handle
, gfp_mask
);
534 EXPORT_SYMBOL(jbd2__journal_restart
);
537 int jbd2_journal_restart(handle_t
*handle
, int nblocks
)
539 return jbd2__journal_restart(handle
, nblocks
, GFP_NOFS
);
541 EXPORT_SYMBOL(jbd2_journal_restart
);
544 * void jbd2_journal_lock_updates () - establish a transaction barrier.
545 * @journal: Journal to establish a barrier on.
547 * This locks out any further updates from being started, and blocks
548 * until all existing updates have completed, returning only once the
549 * journal is in a quiescent state with no updates running.
551 * The journal lock should not be held on entry.
553 void jbd2_journal_lock_updates(journal_t
*journal
)
557 write_lock(&journal
->j_state_lock
);
558 ++journal
->j_barrier_count
;
560 /* Wait until there are no running updates */
562 transaction_t
*transaction
= journal
->j_running_transaction
;
567 spin_lock(&transaction
->t_handle_lock
);
568 prepare_to_wait(&journal
->j_wait_updates
, &wait
,
569 TASK_UNINTERRUPTIBLE
);
570 if (!atomic_read(&transaction
->t_updates
)) {
571 spin_unlock(&transaction
->t_handle_lock
);
572 finish_wait(&journal
->j_wait_updates
, &wait
);
575 spin_unlock(&transaction
->t_handle_lock
);
576 write_unlock(&journal
->j_state_lock
);
578 finish_wait(&journal
->j_wait_updates
, &wait
);
579 write_lock(&journal
->j_state_lock
);
581 write_unlock(&journal
->j_state_lock
);
584 * We have now established a barrier against other normal updates, but
585 * we also need to barrier against other jbd2_journal_lock_updates() calls
586 * to make sure that we serialise special journal-locked operations
589 mutex_lock(&journal
->j_barrier
);
593 * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier
594 * @journal: Journal to release the barrier on.
596 * Release a transaction barrier obtained with jbd2_journal_lock_updates().
598 * Should be called without the journal lock held.
600 void jbd2_journal_unlock_updates (journal_t
*journal
)
602 J_ASSERT(journal
->j_barrier_count
!= 0);
604 mutex_unlock(&journal
->j_barrier
);
605 write_lock(&journal
->j_state_lock
);
606 --journal
->j_barrier_count
;
607 write_unlock(&journal
->j_state_lock
);
608 wake_up(&journal
->j_wait_transaction_locked
);
611 static void warn_dirty_buffer(struct buffer_head
*bh
)
613 char b
[BDEVNAME_SIZE
];
616 "JBD2: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). "
617 "There's a risk of filesystem corruption in case of system "
619 bdevname(bh
->b_bdev
, b
), (unsigned long long)bh
->b_blocknr
);
623 * If the buffer is already part of the current transaction, then there
624 * is nothing we need to do. If it is already part of a prior
625 * transaction which we are still committing to disk, then we need to
626 * make sure that we do not overwrite the old copy: we do copy-out to
627 * preserve the copy going to disk. We also account the buffer against
628 * the handle's metadata buffer credits (unless the buffer is already
629 * part of the transaction, that is).
633 do_get_write_access(handle_t
*handle
, struct journal_head
*jh
,
636 struct buffer_head
*bh
;
637 transaction_t
*transaction
;
640 char *frozen_buffer
= NULL
;
642 unsigned long start_lock
, time_lock
;
644 if (is_handle_aborted(handle
))
647 transaction
= handle
->h_transaction
;
648 journal
= transaction
->t_journal
;
650 jbd_debug(5, "journal_head %p, force_copy %d\n", jh
, force_copy
);
652 JBUFFER_TRACE(jh
, "entry");
656 /* @@@ Need to check for errors here at some point. */
658 start_lock
= jiffies
;
660 jbd_lock_bh_state(bh
);
662 /* If it takes too long to lock the buffer, trace it */
663 time_lock
= jbd2_time_diff(start_lock
, jiffies
);
664 if (time_lock
> HZ
/10)
665 trace_jbd2_lock_buffer_stall(bh
->b_bdev
->bd_dev
,
666 jiffies_to_msecs(time_lock
));
668 /* We now hold the buffer lock so it is safe to query the buffer
669 * state. Is the buffer dirty?
671 * If so, there are two possibilities. The buffer may be
672 * non-journaled, and undergoing a quite legitimate writeback.
673 * Otherwise, it is journaled, and we don't expect dirty buffers
674 * in that state (the buffers should be marked JBD_Dirty
675 * instead.) So either the IO is being done under our own
676 * control and this is a bug, or it's a third party IO such as
677 * dump(8) (which may leave the buffer scheduled for read ---
678 * ie. locked but not dirty) or tune2fs (which may actually have
679 * the buffer dirtied, ugh.) */
681 if (buffer_dirty(bh
)) {
683 * First question: is this buffer already part of the current
684 * transaction or the existing committing transaction?
686 if (jh
->b_transaction
) {
688 jh
->b_transaction
== transaction
||
690 journal
->j_committing_transaction
);
691 if (jh
->b_next_transaction
)
692 J_ASSERT_JH(jh
, jh
->b_next_transaction
==
694 warn_dirty_buffer(bh
);
697 * In any case we need to clean the dirty flag and we must
698 * do it under the buffer lock to be sure we don't race
699 * with running write-out.
701 JBUFFER_TRACE(jh
, "Journalling dirty buffer");
702 clear_buffer_dirty(bh
);
703 set_buffer_jbddirty(bh
);
709 if (is_handle_aborted(handle
)) {
710 jbd_unlock_bh_state(bh
);
716 * The buffer is already part of this transaction if b_transaction or
717 * b_next_transaction points to it
719 if (jh
->b_transaction
== transaction
||
720 jh
->b_next_transaction
== transaction
)
724 * this is the first time this transaction is touching this buffer,
725 * reset the modified flag
730 * If there is already a copy-out version of this buffer, then we don't
731 * need to make another one
733 if (jh
->b_frozen_data
) {
734 JBUFFER_TRACE(jh
, "has frozen data");
735 J_ASSERT_JH(jh
, jh
->b_next_transaction
== NULL
);
736 jh
->b_next_transaction
= transaction
;
740 /* Is there data here we need to preserve? */
742 if (jh
->b_transaction
&& jh
->b_transaction
!= transaction
) {
743 JBUFFER_TRACE(jh
, "owned by older transaction");
744 J_ASSERT_JH(jh
, jh
->b_next_transaction
== NULL
);
745 J_ASSERT_JH(jh
, jh
->b_transaction
==
746 journal
->j_committing_transaction
);
748 /* There is one case we have to be very careful about.
749 * If the committing transaction is currently writing
750 * this buffer out to disk and has NOT made a copy-out,
751 * then we cannot modify the buffer contents at all
752 * right now. The essence of copy-out is that it is the
753 * extra copy, not the primary copy, which gets
754 * journaled. If the primary copy is already going to
755 * disk then we cannot do copy-out here. */
757 if (jh
->b_jlist
== BJ_Shadow
) {
758 DEFINE_WAIT_BIT(wait
, &bh
->b_state
, BH_Unshadow
);
759 wait_queue_head_t
*wqh
;
761 wqh
= bit_waitqueue(&bh
->b_state
, BH_Unshadow
);
763 JBUFFER_TRACE(jh
, "on shadow: sleep");
764 jbd_unlock_bh_state(bh
);
765 /* commit wakes up all shadow buffers after IO */
767 prepare_to_wait(wqh
, &wait
.wait
,
768 TASK_UNINTERRUPTIBLE
);
769 if (jh
->b_jlist
!= BJ_Shadow
)
773 finish_wait(wqh
, &wait
.wait
);
777 /* Only do the copy if the currently-owning transaction
778 * still needs it. If it is on the Forget list, the
779 * committing transaction is past that stage. The
780 * buffer had better remain locked during the kmalloc,
781 * but that should be true --- we hold the journal lock
782 * still and the buffer is already on the BUF_JOURNAL
783 * list so won't be flushed.
785 * Subtle point, though: if this is a get_undo_access,
786 * then we will be relying on the frozen_data to contain
787 * the new value of the committed_data record after the
788 * transaction, so we HAVE to force the frozen_data copy
791 if (jh
->b_jlist
!= BJ_Forget
|| force_copy
) {
792 JBUFFER_TRACE(jh
, "generate frozen data");
793 if (!frozen_buffer
) {
794 JBUFFER_TRACE(jh
, "allocate memory for buffer");
795 jbd_unlock_bh_state(bh
);
797 jbd2_alloc(jh2bh(jh
)->b_size
,
799 if (!frozen_buffer
) {
801 "%s: OOM for frozen_buffer\n",
803 JBUFFER_TRACE(jh
, "oom!");
805 jbd_lock_bh_state(bh
);
810 jh
->b_frozen_data
= frozen_buffer
;
811 frozen_buffer
= NULL
;
814 jh
->b_next_transaction
= transaction
;
819 * Finally, if the buffer is not journaled right now, we need to make
820 * sure it doesn't get written to disk before the caller actually
821 * commits the new data
823 if (!jh
->b_transaction
) {
824 JBUFFER_TRACE(jh
, "no transaction");
825 J_ASSERT_JH(jh
, !jh
->b_next_transaction
);
826 JBUFFER_TRACE(jh
, "file as BJ_Reserved");
827 spin_lock(&journal
->j_list_lock
);
828 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Reserved
);
829 spin_unlock(&journal
->j_list_lock
);
838 J_EXPECT_JH(jh
, buffer_uptodate(jh2bh(jh
)),
839 "Possible IO failure.\n");
840 page
= jh2bh(jh
)->b_page
;
841 offset
= offset_in_page(jh2bh(jh
)->b_data
);
842 source
= kmap_atomic(page
);
843 /* Fire data frozen trigger just before we copy the data */
844 jbd2_buffer_frozen_trigger(jh
, source
+ offset
,
846 memcpy(jh
->b_frozen_data
, source
+offset
, jh2bh(jh
)->b_size
);
847 kunmap_atomic(source
);
850 * Now that the frozen data is saved off, we need to store
851 * any matching triggers.
853 jh
->b_frozen_triggers
= jh
->b_triggers
;
855 jbd_unlock_bh_state(bh
);
858 * If we are about to journal a buffer, then any revoke pending on it is
861 jbd2_journal_cancel_revoke(handle
, jh
);
864 if (unlikely(frozen_buffer
)) /* It's usually NULL */
865 jbd2_free(frozen_buffer
, bh
->b_size
);
867 JBUFFER_TRACE(jh
, "exit");
872 * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
873 * @handle: transaction to add buffer modifications to
874 * @bh: bh to be used for metadata writes
876 * Returns an error code or 0 on success.
878 * In full data journalling mode the buffer may be of type BJ_AsyncData,
879 * because we're write()ing a buffer which is also part of a shared mapping.
882 int jbd2_journal_get_write_access(handle_t
*handle
, struct buffer_head
*bh
)
884 struct journal_head
*jh
= jbd2_journal_add_journal_head(bh
);
887 /* We do not want to get caught playing with fields which the
888 * log thread also manipulates. Make sure that the buffer
889 * completes any outstanding IO before proceeding. */
890 rc
= do_get_write_access(handle
, jh
, 0);
891 jbd2_journal_put_journal_head(jh
);
897 * When the user wants to journal a newly created buffer_head
898 * (ie. getblk() returned a new buffer and we are going to populate it
899 * manually rather than reading off disk), then we need to keep the
900 * buffer_head locked until it has been completely filled with new
901 * data. In this case, we should be able to make the assertion that
902 * the bh is not already part of an existing transaction.
904 * The buffer should already be locked by the caller by this point.
905 * There is no lock ranking violation: it was a newly created,
906 * unlocked buffer beforehand. */
909 * int jbd2_journal_get_create_access () - notify intent to use newly created bh
910 * @handle: transaction to new buffer to
913 * Call this if you create a new bh.
915 int jbd2_journal_get_create_access(handle_t
*handle
, struct buffer_head
*bh
)
917 transaction_t
*transaction
= handle
->h_transaction
;
918 journal_t
*journal
= transaction
->t_journal
;
919 struct journal_head
*jh
= jbd2_journal_add_journal_head(bh
);
922 jbd_debug(5, "journal_head %p\n", jh
);
924 if (is_handle_aborted(handle
))
928 JBUFFER_TRACE(jh
, "entry");
930 * The buffer may already belong to this transaction due to pre-zeroing
931 * in the filesystem's new_block code. It may also be on the previous,
932 * committing transaction's lists, but it HAS to be in Forget state in
933 * that case: the transaction must have deleted the buffer for it to be
936 jbd_lock_bh_state(bh
);
937 spin_lock(&journal
->j_list_lock
);
938 J_ASSERT_JH(jh
, (jh
->b_transaction
== transaction
||
939 jh
->b_transaction
== NULL
||
940 (jh
->b_transaction
== journal
->j_committing_transaction
&&
941 jh
->b_jlist
== BJ_Forget
)));
943 J_ASSERT_JH(jh
, jh
->b_next_transaction
== NULL
);
944 J_ASSERT_JH(jh
, buffer_locked(jh2bh(jh
)));
946 if (jh
->b_transaction
== NULL
) {
948 * Previous jbd2_journal_forget() could have left the buffer
949 * with jbddirty bit set because it was being committed. When
950 * the commit finished, we've filed the buffer for
951 * checkpointing and marked it dirty. Now we are reallocating
952 * the buffer so the transaction freeing it must have
953 * committed and so it's safe to clear the dirty bit.
955 clear_buffer_dirty(jh2bh(jh
));
956 /* first access by this transaction */
959 JBUFFER_TRACE(jh
, "file as BJ_Reserved");
960 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Reserved
);
961 } else if (jh
->b_transaction
== journal
->j_committing_transaction
) {
962 /* first access by this transaction */
965 JBUFFER_TRACE(jh
, "set next transaction");
966 jh
->b_next_transaction
= transaction
;
968 spin_unlock(&journal
->j_list_lock
);
969 jbd_unlock_bh_state(bh
);
972 * akpm: I added this. ext3_alloc_branch can pick up new indirect
973 * blocks which contain freed but then revoked metadata. We need
974 * to cancel the revoke in case we end up freeing it yet again
975 * and the reallocating as data - this would cause a second revoke,
976 * which hits an assertion error.
978 JBUFFER_TRACE(jh
, "cancelling revoke");
979 jbd2_journal_cancel_revoke(handle
, jh
);
981 jbd2_journal_put_journal_head(jh
);
986 * int jbd2_journal_get_undo_access() - Notify intent to modify metadata with
987 * non-rewindable consequences
988 * @handle: transaction
989 * @bh: buffer to undo
991 * Sometimes there is a need to distinguish between metadata which has
992 * been committed to disk and that which has not. The ext3fs code uses
993 * this for freeing and allocating space, we have to make sure that we
994 * do not reuse freed space until the deallocation has been committed,
995 * since if we overwrote that space we would make the delete
996 * un-rewindable in case of a crash.
998 * To deal with that, jbd2_journal_get_undo_access requests write access to a
999 * buffer for parts of non-rewindable operations such as delete
1000 * operations on the bitmaps. The journaling code must keep a copy of
1001 * the buffer's contents prior to the undo_access call until such time
1002 * as we know that the buffer has definitely been committed to disk.
1004 * We never need to know which transaction the committed data is part
1005 * of, buffers touched here are guaranteed to be dirtied later and so
1006 * will be committed to a new transaction in due course, at which point
1007 * we can discard the old committed data pointer.
1009 * Returns error number or 0 on success.
1011 int jbd2_journal_get_undo_access(handle_t
*handle
, struct buffer_head
*bh
)
1014 struct journal_head
*jh
= jbd2_journal_add_journal_head(bh
);
1015 char *committed_data
= NULL
;
1017 JBUFFER_TRACE(jh
, "entry");
1020 * Do this first --- it can drop the journal lock, so we want to
1021 * make sure that obtaining the committed_data is done
1022 * atomically wrt. completion of any outstanding commits.
1024 err
= do_get_write_access(handle
, jh
, 1);
1029 if (!jh
->b_committed_data
) {
1030 committed_data
= jbd2_alloc(jh2bh(jh
)->b_size
, GFP_NOFS
);
1031 if (!committed_data
) {
1032 printk(KERN_EMERG
"%s: No memory for committed data\n",
1039 jbd_lock_bh_state(bh
);
1040 if (!jh
->b_committed_data
) {
1041 /* Copy out the current buffer contents into the
1042 * preserved, committed copy. */
1043 JBUFFER_TRACE(jh
, "generate b_committed data");
1044 if (!committed_data
) {
1045 jbd_unlock_bh_state(bh
);
1049 jh
->b_committed_data
= committed_data
;
1050 committed_data
= NULL
;
1051 memcpy(jh
->b_committed_data
, bh
->b_data
, bh
->b_size
);
1053 jbd_unlock_bh_state(bh
);
1055 jbd2_journal_put_journal_head(jh
);
1056 if (unlikely(committed_data
))
1057 jbd2_free(committed_data
, bh
->b_size
);
1062 * void jbd2_journal_set_triggers() - Add triggers for commit writeout
1063 * @bh: buffer to trigger on
1064 * @type: struct jbd2_buffer_trigger_type containing the trigger(s).
1066 * Set any triggers on this journal_head. This is always safe, because
1067 * triggers for a committing buffer will be saved off, and triggers for
1068 * a running transaction will match the buffer in that transaction.
1070 * Call with NULL to clear the triggers.
1072 void jbd2_journal_set_triggers(struct buffer_head
*bh
,
1073 struct jbd2_buffer_trigger_type
*type
)
1075 struct journal_head
*jh
= jbd2_journal_grab_journal_head(bh
);
1079 jh
->b_triggers
= type
;
1080 jbd2_journal_put_journal_head(jh
);
1083 void jbd2_buffer_frozen_trigger(struct journal_head
*jh
, void *mapped_data
,
1084 struct jbd2_buffer_trigger_type
*triggers
)
1086 struct buffer_head
*bh
= jh2bh(jh
);
1088 if (!triggers
|| !triggers
->t_frozen
)
1091 triggers
->t_frozen(triggers
, bh
, mapped_data
, bh
->b_size
);
1094 void jbd2_buffer_abort_trigger(struct journal_head
*jh
,
1095 struct jbd2_buffer_trigger_type
*triggers
)
1097 if (!triggers
|| !triggers
->t_abort
)
1100 triggers
->t_abort(triggers
, jh2bh(jh
));
1106 * int jbd2_journal_dirty_metadata() - mark a buffer as containing dirty metadata
1107 * @handle: transaction to add buffer to.
1108 * @bh: buffer to mark
1110 * mark dirty metadata which needs to be journaled as part of the current
1113 * The buffer must have previously had jbd2_journal_get_write_access()
1114 * called so that it has a valid journal_head attached to the buffer
1117 * The buffer is placed on the transaction's metadata list and is marked
1118 * as belonging to the transaction.
1120 * Returns error number or 0 on success.
1122 * Special care needs to be taken if the buffer already belongs to the
1123 * current committing transaction (in which case we should have frozen
1124 * data present for that commit). In that case, we don't relink the
1125 * buffer: that only gets done when the old transaction finally
1126 * completes its commit.
1128 int jbd2_journal_dirty_metadata(handle_t
*handle
, struct buffer_head
*bh
)
1130 transaction_t
*transaction
= handle
->h_transaction
;
1131 journal_t
*journal
= transaction
->t_journal
;
1132 struct journal_head
*jh
;
1135 if (is_handle_aborted(handle
))
1137 jh
= jbd2_journal_grab_journal_head(bh
);
1142 jbd_debug(5, "journal_head %p\n", jh
);
1143 JBUFFER_TRACE(jh
, "entry");
1145 jbd_lock_bh_state(bh
);
1147 if (jh
->b_modified
== 0) {
1149 * This buffer's got modified and becoming part
1150 * of the transaction. This needs to be done
1151 * once a transaction -bzzz
1154 if (handle
->h_buffer_credits
<= 0) {
1158 handle
->h_buffer_credits
--;
1162 * fastpath, to avoid expensive locking. If this buffer is already
1163 * on the running transaction's metadata list there is nothing to do.
1164 * Nobody can take it off again because there is a handle open.
1165 * I _think_ we're OK here with SMP barriers - a mistaken decision will
1166 * result in this test being false, so we go in and take the locks.
1168 if (jh
->b_transaction
== transaction
&& jh
->b_jlist
== BJ_Metadata
) {
1169 JBUFFER_TRACE(jh
, "fastpath");
1170 if (unlikely(jh
->b_transaction
!=
1171 journal
->j_running_transaction
)) {
1172 printk(KERN_EMERG
"JBD: %s: "
1173 "jh->b_transaction (%llu, %p, %u) != "
1174 "journal->j_running_transaction (%p, %u)",
1176 (unsigned long long) bh
->b_blocknr
,
1178 jh
->b_transaction
? jh
->b_transaction
->t_tid
: 0,
1179 journal
->j_running_transaction
,
1180 journal
->j_running_transaction
?
1181 journal
->j_running_transaction
->t_tid
: 0);
1187 set_buffer_jbddirty(bh
);
1190 * Metadata already on the current transaction list doesn't
1191 * need to be filed. Metadata on another transaction's list must
1192 * be committing, and will be refiled once the commit completes:
1193 * leave it alone for now.
1195 if (jh
->b_transaction
!= transaction
) {
1196 JBUFFER_TRACE(jh
, "already on other transaction");
1197 if (unlikely(jh
->b_transaction
!=
1198 journal
->j_committing_transaction
)) {
1199 printk(KERN_EMERG
"JBD: %s: "
1200 "jh->b_transaction (%llu, %p, %u) != "
1201 "journal->j_committing_transaction (%p, %u)",
1203 (unsigned long long) bh
->b_blocknr
,
1205 jh
->b_transaction
? jh
->b_transaction
->t_tid
: 0,
1206 journal
->j_committing_transaction
,
1207 journal
->j_committing_transaction
?
1208 journal
->j_committing_transaction
->t_tid
: 0);
1211 if (unlikely(jh
->b_next_transaction
!= transaction
)) {
1212 printk(KERN_EMERG
"JBD: %s: "
1213 "jh->b_next_transaction (%llu, %p, %u) != "
1214 "transaction (%p, %u)",
1216 (unsigned long long) bh
->b_blocknr
,
1217 jh
->b_next_transaction
,
1218 jh
->b_next_transaction
?
1219 jh
->b_next_transaction
->t_tid
: 0,
1220 transaction
, transaction
->t_tid
);
1223 /* And this case is illegal: we can't reuse another
1224 * transaction's data buffer, ever. */
1228 /* That test should have eliminated the following case: */
1229 J_ASSERT_JH(jh
, jh
->b_frozen_data
== NULL
);
1231 JBUFFER_TRACE(jh
, "file as BJ_Metadata");
1232 spin_lock(&journal
->j_list_lock
);
1233 __jbd2_journal_file_buffer(jh
, handle
->h_transaction
, BJ_Metadata
);
1234 spin_unlock(&journal
->j_list_lock
);
1236 jbd_unlock_bh_state(bh
);
1237 jbd2_journal_put_journal_head(jh
);
1239 JBUFFER_TRACE(jh
, "exit");
1244 * void jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1245 * @handle: transaction handle
1246 * @bh: bh to 'forget'
1248 * We can only do the bforget if there are no commits pending against the
1249 * buffer. If the buffer is dirty in the current running transaction we
1250 * can safely unlink it.
1252 * bh may not be a journalled buffer at all - it may be a non-JBD
1253 * buffer which came off the hashtable. Check for this.
1255 * Decrements bh->b_count by one.
1257 * Allow this call even if the handle has aborted --- it may be part of
1258 * the caller's cleanup after an abort.
1260 int jbd2_journal_forget (handle_t
*handle
, struct buffer_head
*bh
)
1262 transaction_t
*transaction
= handle
->h_transaction
;
1263 journal_t
*journal
= transaction
->t_journal
;
1264 struct journal_head
*jh
;
1265 int drop_reserve
= 0;
1267 int was_modified
= 0;
1269 BUFFER_TRACE(bh
, "entry");
1271 jbd_lock_bh_state(bh
);
1272 spin_lock(&journal
->j_list_lock
);
1274 if (!buffer_jbd(bh
))
1278 /* Critical error: attempting to delete a bitmap buffer, maybe?
1279 * Don't do any jbd operations, and return an error. */
1280 if (!J_EXPECT_JH(jh
, !jh
->b_committed_data
,
1281 "inconsistent data on disk")) {
1286 /* keep track of whether or not this transaction modified us */
1287 was_modified
= jh
->b_modified
;
1290 * The buffer's going from the transaction, we must drop
1291 * all references -bzzz
1295 if (jh
->b_transaction
== handle
->h_transaction
) {
1296 J_ASSERT_JH(jh
, !jh
->b_frozen_data
);
1298 /* If we are forgetting a buffer which is already part
1299 * of this transaction, then we can just drop it from
1300 * the transaction immediately. */
1301 clear_buffer_dirty(bh
);
1302 clear_buffer_jbddirty(bh
);
1304 JBUFFER_TRACE(jh
, "belongs to current transaction: unfile");
1307 * we only want to drop a reference if this transaction
1308 * modified the buffer
1314 * We are no longer going to journal this buffer.
1315 * However, the commit of this transaction is still
1316 * important to the buffer: the delete that we are now
1317 * processing might obsolete an old log entry, so by
1318 * committing, we can satisfy the buffer's checkpoint.
1320 * So, if we have a checkpoint on the buffer, we should
1321 * now refile the buffer on our BJ_Forget list so that
1322 * we know to remove the checkpoint after we commit.
1325 if (jh
->b_cp_transaction
) {
1326 __jbd2_journal_temp_unlink_buffer(jh
);
1327 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Forget
);
1329 __jbd2_journal_unfile_buffer(jh
);
1330 if (!buffer_jbd(bh
)) {
1331 spin_unlock(&journal
->j_list_lock
);
1332 jbd_unlock_bh_state(bh
);
1337 } else if (jh
->b_transaction
) {
1338 J_ASSERT_JH(jh
, (jh
->b_transaction
==
1339 journal
->j_committing_transaction
));
1340 /* However, if the buffer is still owned by a prior
1341 * (committing) transaction, we can't drop it yet... */
1342 JBUFFER_TRACE(jh
, "belongs to older transaction");
1343 /* ... but we CAN drop it from the new transaction if we
1344 * have also modified it since the original commit. */
1346 if (jh
->b_next_transaction
) {
1347 J_ASSERT(jh
->b_next_transaction
== transaction
);
1348 jh
->b_next_transaction
= NULL
;
1351 * only drop a reference if this transaction modified
1360 spin_unlock(&journal
->j_list_lock
);
1361 jbd_unlock_bh_state(bh
);
1365 /* no need to reserve log space for this block -bzzz */
1366 handle
->h_buffer_credits
++;
1372 * int jbd2_journal_stop() - complete a transaction
1373 * @handle: tranaction to complete.
1375 * All done for a particular handle.
1377 * There is not much action needed here. We just return any remaining
1378 * buffer credits to the transaction and remove the handle. The only
1379 * complication is that we need to start a commit operation if the
1380 * filesystem is marked for synchronous update.
1382 * jbd2_journal_stop itself will not usually return an error, but it may
1383 * do so in unusual circumstances. In particular, expect it to
1384 * return -EIO if a jbd2_journal_abort has been executed since the
1385 * transaction began.
1387 int jbd2_journal_stop(handle_t
*handle
)
1389 transaction_t
*transaction
= handle
->h_transaction
;
1390 journal_t
*journal
= transaction
->t_journal
;
1391 int err
, wait_for_commit
= 0;
1395 J_ASSERT(journal_current_handle() == handle
);
1397 if (is_handle_aborted(handle
))
1400 J_ASSERT(atomic_read(&transaction
->t_updates
) > 0);
1404 if (--handle
->h_ref
> 0) {
1405 jbd_debug(4, "h_ref %d -> %d\n", handle
->h_ref
+ 1,
1410 jbd_debug(4, "Handle %p going down\n", handle
);
1411 trace_jbd2_handle_stats(journal
->j_fs_dev
->bd_dev
,
1412 handle
->h_transaction
->t_tid
,
1413 handle
->h_type
, handle
->h_line_no
,
1414 jiffies
- handle
->h_start_jiffies
,
1415 handle
->h_sync
, handle
->h_requested_credits
,
1416 (handle
->h_requested_credits
-
1417 handle
->h_buffer_credits
));
1420 * Implement synchronous transaction batching. If the handle
1421 * was synchronous, don't force a commit immediately. Let's
1422 * yield and let another thread piggyback onto this
1423 * transaction. Keep doing that while new threads continue to
1424 * arrive. It doesn't cost much - we're about to run a commit
1425 * and sleep on IO anyway. Speeds up many-threaded, many-dir
1426 * operations by 30x or more...
1428 * We try and optimize the sleep time against what the
1429 * underlying disk can do, instead of having a static sleep
1430 * time. This is useful for the case where our storage is so
1431 * fast that it is more optimal to go ahead and force a flush
1432 * and wait for the transaction to be committed than it is to
1433 * wait for an arbitrary amount of time for new writers to
1434 * join the transaction. We achieve this by measuring how
1435 * long it takes to commit a transaction, and compare it with
1436 * how long this transaction has been running, and if run time
1437 * < commit time then we sleep for the delta and commit. This
1438 * greatly helps super fast disks that would see slowdowns as
1439 * more threads started doing fsyncs.
1441 * But don't do this if this process was the most recent one
1442 * to perform a synchronous write. We do this to detect the
1443 * case where a single process is doing a stream of sync
1444 * writes. No point in waiting for joiners in that case.
1446 * Setting max_batch_time to 0 disables this completely.
1449 if (handle
->h_sync
&& journal
->j_last_sync_writer
!= pid
&&
1450 journal
->j_max_batch_time
) {
1451 u64 commit_time
, trans_time
;
1453 journal
->j_last_sync_writer
= pid
;
1455 read_lock(&journal
->j_state_lock
);
1456 commit_time
= journal
->j_average_commit_time
;
1457 read_unlock(&journal
->j_state_lock
);
1459 trans_time
= ktime_to_ns(ktime_sub(ktime_get(),
1460 transaction
->t_start_time
));
1462 commit_time
= max_t(u64
, commit_time
,
1463 1000*journal
->j_min_batch_time
);
1464 commit_time
= min_t(u64
, commit_time
,
1465 1000*journal
->j_max_batch_time
);
1467 if (trans_time
< commit_time
) {
1468 ktime_t expires
= ktime_add_ns(ktime_get(),
1470 set_current_state(TASK_UNINTERRUPTIBLE
);
1471 schedule_hrtimeout(&expires
, HRTIMER_MODE_ABS
);
1476 transaction
->t_synchronous_commit
= 1;
1477 current
->journal_info
= NULL
;
1478 atomic_sub(handle
->h_buffer_credits
,
1479 &transaction
->t_outstanding_credits
);
1482 * If the handle is marked SYNC, we need to set another commit
1483 * going! We also want to force a commit if the current
1484 * transaction is occupying too much of the log, or if the
1485 * transaction is too old now.
1487 if (handle
->h_sync
||
1488 (atomic_read(&transaction
->t_outstanding_credits
) >
1489 journal
->j_max_transaction_buffers
) ||
1490 time_after_eq(jiffies
, transaction
->t_expires
)) {
1491 /* Do this even for aborted journals: an abort still
1492 * completes the commit thread, it just doesn't write
1493 * anything to disk. */
1495 jbd_debug(2, "transaction too old, requesting commit for "
1496 "handle %p\n", handle
);
1497 /* This is non-blocking */
1498 jbd2_log_start_commit(journal
, transaction
->t_tid
);
1501 * Special case: JBD2_SYNC synchronous updates require us
1502 * to wait for the commit to complete.
1504 if (handle
->h_sync
&& !(current
->flags
& PF_MEMALLOC
))
1505 wait_for_commit
= 1;
1509 * Once we drop t_updates, if it goes to zero the transaction
1510 * could start committing on us and eventually disappear. So
1511 * once we do this, we must not dereference transaction
1514 tid
= transaction
->t_tid
;
1515 if (atomic_dec_and_test(&transaction
->t_updates
)) {
1516 wake_up(&journal
->j_wait_updates
);
1517 if (journal
->j_barrier_count
)
1518 wake_up(&journal
->j_wait_transaction_locked
);
1521 if (wait_for_commit
)
1522 err
= jbd2_log_wait_commit(journal
, tid
);
1524 lock_map_release(&handle
->h_lockdep_map
);
1526 jbd2_free_handle(handle
);
1531 * int jbd2_journal_force_commit() - force any uncommitted transactions
1532 * @journal: journal to force
1534 * For synchronous operations: force any uncommitted transactions
1535 * to disk. May seem kludgy, but it reuses all the handle batching
1536 * code in a very simple manner.
1538 int jbd2_journal_force_commit(journal_t
*journal
)
1543 handle
= jbd2_journal_start(journal
, 1);
1544 if (IS_ERR(handle
)) {
1545 ret
= PTR_ERR(handle
);
1548 ret
= jbd2_journal_stop(handle
);
1555 * List management code snippets: various functions for manipulating the
1556 * transaction buffer lists.
1561 * Append a buffer to a transaction list, given the transaction's list head
1564 * j_list_lock is held.
1566 * jbd_lock_bh_state(jh2bh(jh)) is held.
1570 __blist_add_buffer(struct journal_head
**list
, struct journal_head
*jh
)
1573 jh
->b_tnext
= jh
->b_tprev
= jh
;
1576 /* Insert at the tail of the list to preserve order */
1577 struct journal_head
*first
= *list
, *last
= first
->b_tprev
;
1579 jh
->b_tnext
= first
;
1580 last
->b_tnext
= first
->b_tprev
= jh
;
1585 * Remove a buffer from a transaction list, given the transaction's list
1588 * Called with j_list_lock held, and the journal may not be locked.
1590 * jbd_lock_bh_state(jh2bh(jh)) is held.
1594 __blist_del_buffer(struct journal_head
**list
, struct journal_head
*jh
)
1597 *list
= jh
->b_tnext
;
1601 jh
->b_tprev
->b_tnext
= jh
->b_tnext
;
1602 jh
->b_tnext
->b_tprev
= jh
->b_tprev
;
1606 * Remove a buffer from the appropriate transaction list.
1608 * Note that this function can *change* the value of
1609 * bh->b_transaction->t_buffers, t_forget, t_iobuf_list, t_shadow_list,
1610 * t_log_list or t_reserved_list. If the caller is holding onto a copy of one
1611 * of these pointers, it could go bad. Generally the caller needs to re-read
1612 * the pointer from the transaction_t.
1614 * Called under j_list_lock.
1616 static void __jbd2_journal_temp_unlink_buffer(struct journal_head
*jh
)
1618 struct journal_head
**list
= NULL
;
1619 transaction_t
*transaction
;
1620 struct buffer_head
*bh
= jh2bh(jh
);
1622 J_ASSERT_JH(jh
, jbd_is_locked_bh_state(bh
));
1623 transaction
= jh
->b_transaction
;
1625 assert_spin_locked(&transaction
->t_journal
->j_list_lock
);
1627 J_ASSERT_JH(jh
, jh
->b_jlist
< BJ_Types
);
1628 if (jh
->b_jlist
!= BJ_None
)
1629 J_ASSERT_JH(jh
, transaction
!= NULL
);
1631 switch (jh
->b_jlist
) {
1635 transaction
->t_nr_buffers
--;
1636 J_ASSERT_JH(jh
, transaction
->t_nr_buffers
>= 0);
1637 list
= &transaction
->t_buffers
;
1640 list
= &transaction
->t_forget
;
1643 list
= &transaction
->t_iobuf_list
;
1646 list
= &transaction
->t_shadow_list
;
1649 list
= &transaction
->t_log_list
;
1652 list
= &transaction
->t_reserved_list
;
1656 __blist_del_buffer(list
, jh
);
1657 jh
->b_jlist
= BJ_None
;
1658 if (transaction
&& is_journal_aborted(transaction
->t_journal
))
1659 clear_buffer_jbddirty(bh
);
1660 else if (test_clear_buffer_jbddirty(bh
))
1661 mark_buffer_dirty(bh
); /* Expose it to the VM */
1665 * Remove buffer from all transactions.
1667 * Called with bh_state lock and j_list_lock
1669 * jh and bh may be already freed when this function returns.
1671 static void __jbd2_journal_unfile_buffer(struct journal_head
*jh
)
1673 __jbd2_journal_temp_unlink_buffer(jh
);
1674 jh
->b_transaction
= NULL
;
1675 jbd2_journal_put_journal_head(jh
);
1678 void jbd2_journal_unfile_buffer(journal_t
*journal
, struct journal_head
*jh
)
1680 struct buffer_head
*bh
= jh2bh(jh
);
1682 /* Get reference so that buffer cannot be freed before we unlock it */
1684 jbd_lock_bh_state(bh
);
1685 spin_lock(&journal
->j_list_lock
);
1686 __jbd2_journal_unfile_buffer(jh
);
1687 spin_unlock(&journal
->j_list_lock
);
1688 jbd_unlock_bh_state(bh
);
1693 * Called from jbd2_journal_try_to_free_buffers().
1695 * Called under jbd_lock_bh_state(bh)
1698 __journal_try_to_free_buffer(journal_t
*journal
, struct buffer_head
*bh
)
1700 struct journal_head
*jh
;
1704 if (buffer_locked(bh
) || buffer_dirty(bh
))
1707 if (jh
->b_next_transaction
!= NULL
)
1710 spin_lock(&journal
->j_list_lock
);
1711 if (jh
->b_cp_transaction
!= NULL
&& jh
->b_transaction
== NULL
) {
1712 /* written-back checkpointed metadata buffer */
1713 JBUFFER_TRACE(jh
, "remove from checkpoint list");
1714 __jbd2_journal_remove_checkpoint(jh
);
1716 spin_unlock(&journal
->j_list_lock
);
1722 * int jbd2_journal_try_to_free_buffers() - try to free page buffers.
1723 * @journal: journal for operation
1724 * @page: to try and free
1725 * @gfp_mask: we use the mask to detect how hard should we try to release
1726 * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to
1727 * release the buffers.
1730 * For all the buffers on this page,
1731 * if they are fully written out ordered data, move them onto BUF_CLEAN
1732 * so try_to_free_buffers() can reap them.
1734 * This function returns non-zero if we wish try_to_free_buffers()
1735 * to be called. We do this if the page is releasable by try_to_free_buffers().
1736 * We also do it if the page has locked or dirty buffers and the caller wants
1737 * us to perform sync or async writeout.
1739 * This complicates JBD locking somewhat. We aren't protected by the
1740 * BKL here. We wish to remove the buffer from its committing or
1741 * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
1743 * This may *change* the value of transaction_t->t_datalist, so anyone
1744 * who looks at t_datalist needs to lock against this function.
1746 * Even worse, someone may be doing a jbd2_journal_dirty_data on this
1747 * buffer. So we need to lock against that. jbd2_journal_dirty_data()
1748 * will come out of the lock with the buffer dirty, which makes it
1749 * ineligible for release here.
1751 * Who else is affected by this? hmm... Really the only contender
1752 * is do_get_write_access() - it could be looking at the buffer while
1753 * journal_try_to_free_buffer() is changing its state. But that
1754 * cannot happen because we never reallocate freed data as metadata
1755 * while the data is part of a transaction. Yes?
1757 * Return 0 on failure, 1 on success
1759 int jbd2_journal_try_to_free_buffers(journal_t
*journal
,
1760 struct page
*page
, gfp_t gfp_mask
)
1762 struct buffer_head
*head
;
1763 struct buffer_head
*bh
;
1766 J_ASSERT(PageLocked(page
));
1768 head
= page_buffers(page
);
1771 struct journal_head
*jh
;
1774 * We take our own ref against the journal_head here to avoid
1775 * having to add tons of locking around each instance of
1776 * jbd2_journal_put_journal_head().
1778 jh
= jbd2_journal_grab_journal_head(bh
);
1782 jbd_lock_bh_state(bh
);
1783 __journal_try_to_free_buffer(journal
, bh
);
1784 jbd2_journal_put_journal_head(jh
);
1785 jbd_unlock_bh_state(bh
);
1788 } while ((bh
= bh
->b_this_page
) != head
);
1790 ret
= try_to_free_buffers(page
);
1797 * This buffer is no longer needed. If it is on an older transaction's
1798 * checkpoint list we need to record it on this transaction's forget list
1799 * to pin this buffer (and hence its checkpointing transaction) down until
1800 * this transaction commits. If the buffer isn't on a checkpoint list, we
1802 * Returns non-zero if JBD no longer has an interest in the buffer.
1804 * Called under j_list_lock.
1806 * Called under jbd_lock_bh_state(bh).
1808 static int __dispose_buffer(struct journal_head
*jh
, transaction_t
*transaction
)
1811 struct buffer_head
*bh
= jh2bh(jh
);
1813 if (jh
->b_cp_transaction
) {
1814 JBUFFER_TRACE(jh
, "on running+cp transaction");
1815 __jbd2_journal_temp_unlink_buffer(jh
);
1817 * We don't want to write the buffer anymore, clear the
1818 * bit so that we don't confuse checks in
1819 * __journal_file_buffer
1821 clear_buffer_dirty(bh
);
1822 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Forget
);
1825 JBUFFER_TRACE(jh
, "on running transaction");
1826 __jbd2_journal_unfile_buffer(jh
);
1832 * jbd2_journal_invalidatepage
1834 * This code is tricky. It has a number of cases to deal with.
1836 * There are two invariants which this code relies on:
1838 * i_size must be updated on disk before we start calling invalidatepage on the
1841 * This is done in ext3 by defining an ext3_setattr method which
1842 * updates i_size before truncate gets going. By maintaining this
1843 * invariant, we can be sure that it is safe to throw away any buffers
1844 * attached to the current transaction: once the transaction commits,
1845 * we know that the data will not be needed.
1847 * Note however that we can *not* throw away data belonging to the
1848 * previous, committing transaction!
1850 * Any disk blocks which *are* part of the previous, committing
1851 * transaction (and which therefore cannot be discarded immediately) are
1852 * not going to be reused in the new running transaction
1854 * The bitmap committed_data images guarantee this: any block which is
1855 * allocated in one transaction and removed in the next will be marked
1856 * as in-use in the committed_data bitmap, so cannot be reused until
1857 * the next transaction to delete the block commits. This means that
1858 * leaving committing buffers dirty is quite safe: the disk blocks
1859 * cannot be reallocated to a different file and so buffer aliasing is
1863 * The above applies mainly to ordered data mode. In writeback mode we
1864 * don't make guarantees about the order in which data hits disk --- in
1865 * particular we don't guarantee that new dirty data is flushed before
1866 * transaction commit --- so it is always safe just to discard data
1867 * immediately in that mode. --sct
1871 * The journal_unmap_buffer helper function returns zero if the buffer
1872 * concerned remains pinned as an anonymous buffer belonging to an older
1875 * We're outside-transaction here. Either or both of j_running_transaction
1876 * and j_committing_transaction may be NULL.
1878 static int journal_unmap_buffer(journal_t
*journal
, struct buffer_head
*bh
,
1881 transaction_t
*transaction
;
1882 struct journal_head
*jh
;
1885 BUFFER_TRACE(bh
, "entry");
1888 * It is safe to proceed here without the j_list_lock because the
1889 * buffers cannot be stolen by try_to_free_buffers as long as we are
1890 * holding the page lock. --sct
1893 if (!buffer_jbd(bh
))
1894 goto zap_buffer_unlocked
;
1896 /* OK, we have data buffer in journaled mode */
1897 write_lock(&journal
->j_state_lock
);
1898 jbd_lock_bh_state(bh
);
1899 spin_lock(&journal
->j_list_lock
);
1901 jh
= jbd2_journal_grab_journal_head(bh
);
1903 goto zap_buffer_no_jh
;
1906 * We cannot remove the buffer from checkpoint lists until the
1907 * transaction adding inode to orphan list (let's call it T)
1908 * is committed. Otherwise if the transaction changing the
1909 * buffer would be cleaned from the journal before T is
1910 * committed, a crash will cause that the correct contents of
1911 * the buffer will be lost. On the other hand we have to
1912 * clear the buffer dirty bit at latest at the moment when the
1913 * transaction marking the buffer as freed in the filesystem
1914 * structures is committed because from that moment on the
1915 * block can be reallocated and used by a different page.
1916 * Since the block hasn't been freed yet but the inode has
1917 * already been added to orphan list, it is safe for us to add
1918 * the buffer to BJ_Forget list of the newest transaction.
1920 * Also we have to clear buffer_mapped flag of a truncated buffer
1921 * because the buffer_head may be attached to the page straddling
1922 * i_size (can happen only when blocksize < pagesize) and thus the
1923 * buffer_head can be reused when the file is extended again. So we end
1924 * up keeping around invalidated buffers attached to transactions'
1925 * BJ_Forget list just to stop checkpointing code from cleaning up
1926 * the transaction this buffer was modified in.
1928 transaction
= jh
->b_transaction
;
1929 if (transaction
== NULL
) {
1930 /* First case: not on any transaction. If it
1931 * has no checkpoint link, then we can zap it:
1932 * it's a writeback-mode buffer so we don't care
1933 * if it hits disk safely. */
1934 if (!jh
->b_cp_transaction
) {
1935 JBUFFER_TRACE(jh
, "not on any transaction: zap");
1939 if (!buffer_dirty(bh
)) {
1940 /* bdflush has written it. We can drop it now */
1941 __jbd2_journal_remove_checkpoint(jh
);
1945 /* OK, it must be in the journal but still not
1946 * written fully to disk: it's metadata or
1947 * journaled data... */
1949 if (journal
->j_running_transaction
) {
1950 /* ... and once the current transaction has
1951 * committed, the buffer won't be needed any
1953 JBUFFER_TRACE(jh
, "checkpointed: add to BJ_Forget");
1954 may_free
= __dispose_buffer(jh
,
1955 journal
->j_running_transaction
);
1958 /* There is no currently-running transaction. So the
1959 * orphan record which we wrote for this file must have
1960 * passed into commit. We must attach this buffer to
1961 * the committing transaction, if it exists. */
1962 if (journal
->j_committing_transaction
) {
1963 JBUFFER_TRACE(jh
, "give to committing trans");
1964 may_free
= __dispose_buffer(jh
,
1965 journal
->j_committing_transaction
);
1968 /* The orphan record's transaction has
1969 * committed. We can cleanse this buffer */
1970 clear_buffer_jbddirty(bh
);
1971 __jbd2_journal_remove_checkpoint(jh
);
1975 } else if (transaction
== journal
->j_committing_transaction
) {
1976 JBUFFER_TRACE(jh
, "on committing transaction");
1978 * The buffer is committing, we simply cannot touch
1979 * it. If the page is straddling i_size we have to wait
1980 * for commit and try again.
1983 jbd2_journal_put_journal_head(jh
);
1984 spin_unlock(&journal
->j_list_lock
);
1985 jbd_unlock_bh_state(bh
);
1986 write_unlock(&journal
->j_state_lock
);
1990 * OK, buffer won't be reachable after truncate. We just set
1991 * j_next_transaction to the running transaction (if there is
1992 * one) and mark buffer as freed so that commit code knows it
1993 * should clear dirty bits when it is done with the buffer.
1995 set_buffer_freed(bh
);
1996 if (journal
->j_running_transaction
&& buffer_jbddirty(bh
))
1997 jh
->b_next_transaction
= journal
->j_running_transaction
;
1998 jbd2_journal_put_journal_head(jh
);
1999 spin_unlock(&journal
->j_list_lock
);
2000 jbd_unlock_bh_state(bh
);
2001 write_unlock(&journal
->j_state_lock
);
2004 /* Good, the buffer belongs to the running transaction.
2005 * We are writing our own transaction's data, not any
2006 * previous one's, so it is safe to throw it away
2007 * (remember that we expect the filesystem to have set
2008 * i_size already for this truncate so recovery will not
2009 * expose the disk blocks we are discarding here.) */
2010 J_ASSERT_JH(jh
, transaction
== journal
->j_running_transaction
);
2011 JBUFFER_TRACE(jh
, "on running transaction");
2012 may_free
= __dispose_buffer(jh
, transaction
);
2017 * This is tricky. Although the buffer is truncated, it may be reused
2018 * if blocksize < pagesize and it is attached to the page straddling
2019 * EOF. Since the buffer might have been added to BJ_Forget list of the
2020 * running transaction, journal_get_write_access() won't clear
2021 * b_modified and credit accounting gets confused. So clear b_modified
2025 jbd2_journal_put_journal_head(jh
);
2027 spin_unlock(&journal
->j_list_lock
);
2028 jbd_unlock_bh_state(bh
);
2029 write_unlock(&journal
->j_state_lock
);
2030 zap_buffer_unlocked
:
2031 clear_buffer_dirty(bh
);
2032 J_ASSERT_BH(bh
, !buffer_jbddirty(bh
));
2033 clear_buffer_mapped(bh
);
2034 clear_buffer_req(bh
);
2035 clear_buffer_new(bh
);
2036 clear_buffer_delay(bh
);
2037 clear_buffer_unwritten(bh
);
2043 * void jbd2_journal_invalidatepage()
2044 * @journal: journal to use for flush...
2045 * @page: page to flush
2046 * @offset: length of page to invalidate.
2048 * Reap page buffers containing data after offset in page. Can return -EBUSY
2049 * if buffers are part of the committing transaction and the page is straddling
2050 * i_size. Caller then has to wait for current commit and try again.
2052 int jbd2_journal_invalidatepage(journal_t
*journal
,
2054 unsigned long offset
)
2056 struct buffer_head
*head
, *bh
, *next
;
2057 unsigned int curr_off
= 0;
2061 if (!PageLocked(page
))
2063 if (!page_has_buffers(page
))
2066 /* We will potentially be playing with lists other than just the
2067 * data lists (especially for journaled data mode), so be
2068 * cautious in our locking. */
2070 head
= bh
= page_buffers(page
);
2072 unsigned int next_off
= curr_off
+ bh
->b_size
;
2073 next
= bh
->b_this_page
;
2075 if (offset
<= curr_off
) {
2076 /* This block is wholly outside the truncation point */
2078 ret
= journal_unmap_buffer(journal
, bh
, offset
> 0);
2084 curr_off
= next_off
;
2087 } while (bh
!= head
);
2090 if (may_free
&& try_to_free_buffers(page
))
2091 J_ASSERT(!page_has_buffers(page
));
2097 * File a buffer on the given transaction list.
2099 void __jbd2_journal_file_buffer(struct journal_head
*jh
,
2100 transaction_t
*transaction
, int jlist
)
2102 struct journal_head
**list
= NULL
;
2104 struct buffer_head
*bh
= jh2bh(jh
);
2106 J_ASSERT_JH(jh
, jbd_is_locked_bh_state(bh
));
2107 assert_spin_locked(&transaction
->t_journal
->j_list_lock
);
2109 J_ASSERT_JH(jh
, jh
->b_jlist
< BJ_Types
);
2110 J_ASSERT_JH(jh
, jh
->b_transaction
== transaction
||
2111 jh
->b_transaction
== NULL
);
2113 if (jh
->b_transaction
&& jh
->b_jlist
== jlist
)
2116 if (jlist
== BJ_Metadata
|| jlist
== BJ_Reserved
||
2117 jlist
== BJ_Shadow
|| jlist
== BJ_Forget
) {
2119 * For metadata buffers, we track dirty bit in buffer_jbddirty
2120 * instead of buffer_dirty. We should not see a dirty bit set
2121 * here because we clear it in do_get_write_access but e.g.
2122 * tune2fs can modify the sb and set the dirty bit at any time
2123 * so we try to gracefully handle that.
2125 if (buffer_dirty(bh
))
2126 warn_dirty_buffer(bh
);
2127 if (test_clear_buffer_dirty(bh
) ||
2128 test_clear_buffer_jbddirty(bh
))
2132 if (jh
->b_transaction
)
2133 __jbd2_journal_temp_unlink_buffer(jh
);
2135 jbd2_journal_grab_journal_head(bh
);
2136 jh
->b_transaction
= transaction
;
2140 J_ASSERT_JH(jh
, !jh
->b_committed_data
);
2141 J_ASSERT_JH(jh
, !jh
->b_frozen_data
);
2144 transaction
->t_nr_buffers
++;
2145 list
= &transaction
->t_buffers
;
2148 list
= &transaction
->t_forget
;
2151 list
= &transaction
->t_iobuf_list
;
2154 list
= &transaction
->t_shadow_list
;
2157 list
= &transaction
->t_log_list
;
2160 list
= &transaction
->t_reserved_list
;
2164 __blist_add_buffer(list
, jh
);
2165 jh
->b_jlist
= jlist
;
2168 set_buffer_jbddirty(bh
);
2171 void jbd2_journal_file_buffer(struct journal_head
*jh
,
2172 transaction_t
*transaction
, int jlist
)
2174 jbd_lock_bh_state(jh2bh(jh
));
2175 spin_lock(&transaction
->t_journal
->j_list_lock
);
2176 __jbd2_journal_file_buffer(jh
, transaction
, jlist
);
2177 spin_unlock(&transaction
->t_journal
->j_list_lock
);
2178 jbd_unlock_bh_state(jh2bh(jh
));
2182 * Remove a buffer from its current buffer list in preparation for
2183 * dropping it from its current transaction entirely. If the buffer has
2184 * already started to be used by a subsequent transaction, refile the
2185 * buffer on that transaction's metadata list.
2187 * Called under j_list_lock
2188 * Called under jbd_lock_bh_state(jh2bh(jh))
2190 * jh and bh may be already free when this function returns
2192 void __jbd2_journal_refile_buffer(struct journal_head
*jh
)
2194 int was_dirty
, jlist
;
2195 struct buffer_head
*bh
= jh2bh(jh
);
2197 J_ASSERT_JH(jh
, jbd_is_locked_bh_state(bh
));
2198 if (jh
->b_transaction
)
2199 assert_spin_locked(&jh
->b_transaction
->t_journal
->j_list_lock
);
2201 /* If the buffer is now unused, just drop it. */
2202 if (jh
->b_next_transaction
== NULL
) {
2203 __jbd2_journal_unfile_buffer(jh
);
2208 * It has been modified by a later transaction: add it to the new
2209 * transaction's metadata list.
2212 was_dirty
= test_clear_buffer_jbddirty(bh
);
2213 __jbd2_journal_temp_unlink_buffer(jh
);
2215 * We set b_transaction here because b_next_transaction will inherit
2216 * our jh reference and thus __jbd2_journal_file_buffer() must not
2219 jh
->b_transaction
= jh
->b_next_transaction
;
2220 jh
->b_next_transaction
= NULL
;
2221 if (buffer_freed(bh
))
2223 else if (jh
->b_modified
)
2224 jlist
= BJ_Metadata
;
2226 jlist
= BJ_Reserved
;
2227 __jbd2_journal_file_buffer(jh
, jh
->b_transaction
, jlist
);
2228 J_ASSERT_JH(jh
, jh
->b_transaction
->t_state
== T_RUNNING
);
2231 set_buffer_jbddirty(bh
);
2235 * __jbd2_journal_refile_buffer() with necessary locking added. We take our
2236 * bh reference so that we can safely unlock bh.
2238 * The jh and bh may be freed by this call.
2240 void jbd2_journal_refile_buffer(journal_t
*journal
, struct journal_head
*jh
)
2242 struct buffer_head
*bh
= jh2bh(jh
);
2244 /* Get reference so that buffer cannot be freed before we unlock it */
2246 jbd_lock_bh_state(bh
);
2247 spin_lock(&journal
->j_list_lock
);
2248 __jbd2_journal_refile_buffer(jh
);
2249 jbd_unlock_bh_state(bh
);
2250 spin_unlock(&journal
->j_list_lock
);
2255 * File inode in the inode list of the handle's transaction
2257 int jbd2_journal_file_inode(handle_t
*handle
, struct jbd2_inode
*jinode
)
2259 transaction_t
*transaction
= handle
->h_transaction
;
2260 journal_t
*journal
= transaction
->t_journal
;
2262 if (is_handle_aborted(handle
))
2265 jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode
->i_vfs_inode
->i_ino
,
2266 transaction
->t_tid
);
2269 * First check whether inode isn't already on the transaction's
2270 * lists without taking the lock. Note that this check is safe
2271 * without the lock as we cannot race with somebody removing inode
2272 * from the transaction. The reason is that we remove inode from the
2273 * transaction only in journal_release_jbd_inode() and when we commit
2274 * the transaction. We are guarded from the first case by holding
2275 * a reference to the inode. We are safe against the second case
2276 * because if jinode->i_transaction == transaction, commit code
2277 * cannot touch the transaction because we hold reference to it,
2278 * and if jinode->i_next_transaction == transaction, commit code
2279 * will only file the inode where we want it.
2281 if (jinode
->i_transaction
== transaction
||
2282 jinode
->i_next_transaction
== transaction
)
2285 spin_lock(&journal
->j_list_lock
);
2287 if (jinode
->i_transaction
== transaction
||
2288 jinode
->i_next_transaction
== transaction
)
2292 * We only ever set this variable to 1 so the test is safe. Since
2293 * t_need_data_flush is likely to be set, we do the test to save some
2294 * cacheline bouncing
2296 if (!transaction
->t_need_data_flush
)
2297 transaction
->t_need_data_flush
= 1;
2298 /* On some different transaction's list - should be
2299 * the committing one */
2300 if (jinode
->i_transaction
) {
2301 J_ASSERT(jinode
->i_next_transaction
== NULL
);
2302 J_ASSERT(jinode
->i_transaction
==
2303 journal
->j_committing_transaction
);
2304 jinode
->i_next_transaction
= transaction
;
2307 /* Not on any transaction list... */
2308 J_ASSERT(!jinode
->i_next_transaction
);
2309 jinode
->i_transaction
= transaction
;
2310 list_add(&jinode
->i_list
, &transaction
->t_inode_list
);
2312 spin_unlock(&journal
->j_list_lock
);
2318 * File truncate and transaction commit interact with each other in a
2319 * non-trivial way. If a transaction writing data block A is
2320 * committing, we cannot discard the data by truncate until we have
2321 * written them. Otherwise if we crashed after the transaction with
2322 * write has committed but before the transaction with truncate has
2323 * committed, we could see stale data in block A. This function is a
2324 * helper to solve this problem. It starts writeout of the truncated
2325 * part in case it is in the committing transaction.
2327 * Filesystem code must call this function when inode is journaled in
2328 * ordered mode before truncation happens and after the inode has been
2329 * placed on orphan list with the new inode size. The second condition
2330 * avoids the race that someone writes new data and we start
2331 * committing the transaction after this function has been called but
2332 * before a transaction for truncate is started (and furthermore it
2333 * allows us to optimize the case where the addition to orphan list
2334 * happens in the same transaction as write --- we don't have to write
2335 * any data in such case).
2337 int jbd2_journal_begin_ordered_truncate(journal_t
*journal
,
2338 struct jbd2_inode
*jinode
,
2341 transaction_t
*inode_trans
, *commit_trans
;
2344 /* This is a quick check to avoid locking if not necessary */
2345 if (!jinode
->i_transaction
)
2347 /* Locks are here just to force reading of recent values, it is
2348 * enough that the transaction was not committing before we started
2349 * a transaction adding the inode to orphan list */
2350 read_lock(&journal
->j_state_lock
);
2351 commit_trans
= journal
->j_committing_transaction
;
2352 read_unlock(&journal
->j_state_lock
);
2353 spin_lock(&journal
->j_list_lock
);
2354 inode_trans
= jinode
->i_transaction
;
2355 spin_unlock(&journal
->j_list_lock
);
2356 if (inode_trans
== commit_trans
) {
2357 ret
= filemap_fdatawrite_range(jinode
->i_vfs_inode
->i_mapping
,
2358 new_size
, LLONG_MAX
);
2360 jbd2_journal_abort(journal
, ret
);