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>
32 #include <linux/sched/mm.h>
34 #include <trace/events/jbd2.h>
36 static void __jbd2_journal_temp_unlink_buffer(struct journal_head
*jh
);
37 static void __jbd2_journal_unfile_buffer(struct journal_head
*jh
);
39 static struct kmem_cache
*transaction_cache
;
40 int __init
jbd2_journal_init_transaction_cache(void)
42 J_ASSERT(!transaction_cache
);
43 transaction_cache
= kmem_cache_create("jbd2_transaction_s",
44 sizeof(transaction_t
),
46 SLAB_HWCACHE_ALIGN
|SLAB_TEMPORARY
,
48 if (transaction_cache
)
53 void jbd2_journal_destroy_transaction_cache(void)
55 if (transaction_cache
) {
56 kmem_cache_destroy(transaction_cache
);
57 transaction_cache
= NULL
;
61 void jbd2_journal_free_transaction(transaction_t
*transaction
)
63 if (unlikely(ZERO_OR_NULL_PTR(transaction
)))
65 kmem_cache_free(transaction_cache
, transaction
);
69 * jbd2_get_transaction: obtain a new transaction_t object.
71 * Simply allocate and initialise a new transaction. Create it in
72 * RUNNING state and add it to the current journal (which should not
73 * have an existing running transaction: we only make a new transaction
74 * once we have started to commit the old one).
77 * The journal MUST be locked. We don't perform atomic mallocs on the
78 * new transaction and we can't block without protecting against other
79 * processes trying to touch the journal while it is in transition.
83 static transaction_t
*
84 jbd2_get_transaction(journal_t
*journal
, transaction_t
*transaction
)
86 transaction
->t_journal
= journal
;
87 transaction
->t_state
= T_RUNNING
;
88 transaction
->t_start_time
= ktime_get();
89 transaction
->t_tid
= journal
->j_transaction_sequence
++;
90 transaction
->t_expires
= jiffies
+ journal
->j_commit_interval
;
91 spin_lock_init(&transaction
->t_handle_lock
);
92 atomic_set(&transaction
->t_updates
, 0);
93 atomic_set(&transaction
->t_outstanding_credits
,
94 atomic_read(&journal
->j_reserved_credits
));
95 atomic_set(&transaction
->t_handle_count
, 0);
96 INIT_LIST_HEAD(&transaction
->t_inode_list
);
97 INIT_LIST_HEAD(&transaction
->t_private_list
);
99 /* Set up the commit timer for the new transaction. */
100 journal
->j_commit_timer
.expires
= round_jiffies_up(transaction
->t_expires
);
101 add_timer(&journal
->j_commit_timer
);
103 J_ASSERT(journal
->j_running_transaction
== NULL
);
104 journal
->j_running_transaction
= transaction
;
105 transaction
->t_max_wait
= 0;
106 transaction
->t_start
= jiffies
;
107 transaction
->t_requested
= 0;
115 * A handle_t is an object which represents a single atomic update to a
116 * filesystem, and which tracks all of the modifications which form part
117 * of that one update.
121 * Update transaction's maximum wait time, if debugging is enabled.
123 * In order for t_max_wait to be reliable, it must be protected by a
124 * lock. But doing so will mean that start_this_handle() can not be
125 * run in parallel on SMP systems, which limits our scalability. So
126 * unless debugging is enabled, we no longer update t_max_wait, which
127 * means that maximum wait time reported by the jbd2_run_stats
128 * tracepoint will always be zero.
130 static inline void update_t_max_wait(transaction_t
*transaction
,
133 #ifdef CONFIG_JBD2_DEBUG
134 if (jbd2_journal_enable_debug
&&
135 time_after(transaction
->t_start
, ts
)) {
136 ts
= jbd2_time_diff(ts
, transaction
->t_start
);
137 spin_lock(&transaction
->t_handle_lock
);
138 if (ts
> transaction
->t_max_wait
)
139 transaction
->t_max_wait
= ts
;
140 spin_unlock(&transaction
->t_handle_lock
);
146 * Wait until running transaction passes T_LOCKED state. Also starts the commit
147 * if needed. The function expects running transaction to exist and releases
150 static void wait_transaction_locked(journal_t
*journal
)
151 __releases(journal
->j_state_lock
)
155 tid_t tid
= journal
->j_running_transaction
->t_tid
;
157 prepare_to_wait(&journal
->j_wait_transaction_locked
, &wait
,
158 TASK_UNINTERRUPTIBLE
);
159 need_to_start
= !tid_geq(journal
->j_commit_request
, tid
);
160 read_unlock(&journal
->j_state_lock
);
162 jbd2_log_start_commit(journal
, tid
);
163 jbd2_might_wait_for_commit(journal
);
165 finish_wait(&journal
->j_wait_transaction_locked
, &wait
);
168 static void sub_reserved_credits(journal_t
*journal
, int blocks
)
170 atomic_sub(blocks
, &journal
->j_reserved_credits
);
171 wake_up(&journal
->j_wait_reserved
);
175 * Wait until we can add credits for handle to the running transaction. Called
176 * with j_state_lock held for reading. Returns 0 if handle joined the running
177 * transaction. Returns 1 if we had to wait, j_state_lock is dropped, and
180 static int add_transaction_credits(journal_t
*journal
, int blocks
,
183 transaction_t
*t
= journal
->j_running_transaction
;
185 int total
= blocks
+ rsv_blocks
;
188 * If the current transaction is locked down for commit, wait
189 * for the lock to be released.
191 if (t
->t_state
== T_LOCKED
) {
192 wait_transaction_locked(journal
);
197 * If there is not enough space left in the log to write all
198 * potential buffers requested by this operation, we need to
199 * stall pending a log checkpoint to free some more log space.
201 needed
= atomic_add_return(total
, &t
->t_outstanding_credits
);
202 if (needed
> journal
->j_max_transaction_buffers
) {
204 * If the current transaction is already too large,
205 * then start to commit it: we can then go back and
206 * attach this handle to a new transaction.
208 atomic_sub(total
, &t
->t_outstanding_credits
);
211 * Is the number of reserved credits in the current transaction too
212 * big to fit this handle? Wait until reserved credits are freed.
214 if (atomic_read(&journal
->j_reserved_credits
) + total
>
215 journal
->j_max_transaction_buffers
) {
216 read_unlock(&journal
->j_state_lock
);
217 jbd2_might_wait_for_commit(journal
);
218 wait_event(journal
->j_wait_reserved
,
219 atomic_read(&journal
->j_reserved_credits
) + total
<=
220 journal
->j_max_transaction_buffers
);
224 wait_transaction_locked(journal
);
229 * The commit code assumes that it can get enough log space
230 * without forcing a checkpoint. This is *critical* for
231 * correctness: a checkpoint of a buffer which is also
232 * associated with a committing transaction creates a deadlock,
233 * so commit simply cannot force through checkpoints.
235 * We must therefore ensure the necessary space in the journal
236 * *before* starting to dirty potentially checkpointed buffers
237 * in the new transaction.
239 if (jbd2_log_space_left(journal
) < jbd2_space_needed(journal
)) {
240 atomic_sub(total
, &t
->t_outstanding_credits
);
241 read_unlock(&journal
->j_state_lock
);
242 jbd2_might_wait_for_commit(journal
);
243 write_lock(&journal
->j_state_lock
);
244 if (jbd2_log_space_left(journal
) < jbd2_space_needed(journal
))
245 __jbd2_log_wait_for_space(journal
);
246 write_unlock(&journal
->j_state_lock
);
250 /* No reservation? We are done... */
254 needed
= atomic_add_return(rsv_blocks
, &journal
->j_reserved_credits
);
255 /* We allow at most half of a transaction to be reserved */
256 if (needed
> journal
->j_max_transaction_buffers
/ 2) {
257 sub_reserved_credits(journal
, rsv_blocks
);
258 atomic_sub(total
, &t
->t_outstanding_credits
);
259 read_unlock(&journal
->j_state_lock
);
260 jbd2_might_wait_for_commit(journal
);
261 wait_event(journal
->j_wait_reserved
,
262 atomic_read(&journal
->j_reserved_credits
) + rsv_blocks
263 <= journal
->j_max_transaction_buffers
/ 2);
270 * start_this_handle: Given a handle, deal with any locking or stalling
271 * needed to make sure that there is enough journal space for the handle
272 * to begin. Attach the handle to a transaction and set up the
273 * transaction's buffer credits.
276 static int start_this_handle(journal_t
*journal
, handle_t
*handle
,
279 transaction_t
*transaction
, *new_transaction
= NULL
;
280 int blocks
= handle
->h_buffer_credits
;
282 unsigned long ts
= jiffies
;
284 if (handle
->h_rsv_handle
)
285 rsv_blocks
= handle
->h_rsv_handle
->h_buffer_credits
;
288 * Limit the number of reserved credits to 1/2 of maximum transaction
289 * size and limit the number of total credits to not exceed maximum
290 * transaction size per operation.
292 if ((rsv_blocks
> journal
->j_max_transaction_buffers
/ 2) ||
293 (rsv_blocks
+ blocks
> journal
->j_max_transaction_buffers
)) {
294 printk(KERN_ERR
"JBD2: %s wants too many credits "
295 "credits:%d rsv_credits:%d max:%d\n",
296 current
->comm
, blocks
, rsv_blocks
,
297 journal
->j_max_transaction_buffers
);
303 if (!journal
->j_running_transaction
) {
305 * If __GFP_FS is not present, then we may be being called from
306 * inside the fs writeback layer, so we MUST NOT fail.
308 if ((gfp_mask
& __GFP_FS
) == 0)
309 gfp_mask
|= __GFP_NOFAIL
;
310 new_transaction
= kmem_cache_zalloc(transaction_cache
,
312 if (!new_transaction
)
316 jbd_debug(3, "New handle %p going live.\n", handle
);
319 * We need to hold j_state_lock until t_updates has been incremented,
320 * for proper journal barrier handling
323 read_lock(&journal
->j_state_lock
);
324 BUG_ON(journal
->j_flags
& JBD2_UNMOUNT
);
325 if (is_journal_aborted(journal
) ||
326 (journal
->j_errno
!= 0 && !(journal
->j_flags
& JBD2_ACK_ERR
))) {
327 read_unlock(&journal
->j_state_lock
);
328 jbd2_journal_free_transaction(new_transaction
);
333 * Wait on the journal's transaction barrier if necessary. Specifically
334 * we allow reserved handles to proceed because otherwise commit could
335 * deadlock on page writeback not being able to complete.
337 if (!handle
->h_reserved
&& journal
->j_barrier_count
) {
338 read_unlock(&journal
->j_state_lock
);
339 wait_event(journal
->j_wait_transaction_locked
,
340 journal
->j_barrier_count
== 0);
344 if (!journal
->j_running_transaction
) {
345 read_unlock(&journal
->j_state_lock
);
346 if (!new_transaction
)
347 goto alloc_transaction
;
348 write_lock(&journal
->j_state_lock
);
349 if (!journal
->j_running_transaction
&&
350 (handle
->h_reserved
|| !journal
->j_barrier_count
)) {
351 jbd2_get_transaction(journal
, new_transaction
);
352 new_transaction
= NULL
;
354 write_unlock(&journal
->j_state_lock
);
358 transaction
= journal
->j_running_transaction
;
360 if (!handle
->h_reserved
) {
361 /* We may have dropped j_state_lock - restart in that case */
362 if (add_transaction_credits(journal
, blocks
, rsv_blocks
))
366 * We have handle reserved so we are allowed to join T_LOCKED
367 * transaction and we don't have to check for transaction size
370 sub_reserved_credits(journal
, blocks
);
371 handle
->h_reserved
= 0;
374 /* OK, account for the buffers that this operation expects to
375 * use and add the handle to the running transaction.
377 update_t_max_wait(transaction
, ts
);
378 handle
->h_transaction
= transaction
;
379 handle
->h_requested_credits
= blocks
;
380 handle
->h_start_jiffies
= jiffies
;
381 atomic_inc(&transaction
->t_updates
);
382 atomic_inc(&transaction
->t_handle_count
);
383 jbd_debug(4, "Handle %p given %d credits (total %d, free %lu)\n",
385 atomic_read(&transaction
->t_outstanding_credits
),
386 jbd2_log_space_left(journal
));
387 read_unlock(&journal
->j_state_lock
);
388 current
->journal_info
= handle
;
390 rwsem_acquire_read(&journal
->j_trans_commit_map
, 0, 0, _THIS_IP_
);
391 jbd2_journal_free_transaction(new_transaction
);
393 * Ensure that no allocations done while the transaction is open are
394 * going to recurse back to the fs layer.
396 handle
->saved_alloc_context
= memalloc_nofs_save();
400 /* Allocate a new handle. This should probably be in a slab... */
401 static handle_t
*new_handle(int nblocks
)
403 handle_t
*handle
= jbd2_alloc_handle(GFP_NOFS
);
406 handle
->h_buffer_credits
= nblocks
;
412 handle_t
*jbd2__journal_start(journal_t
*journal
, int nblocks
, int rsv_blocks
,
413 gfp_t gfp_mask
, unsigned int type
,
414 unsigned int line_no
)
416 handle_t
*handle
= journal_current_handle();
420 return ERR_PTR(-EROFS
);
423 J_ASSERT(handle
->h_transaction
->t_journal
== journal
);
428 handle
= new_handle(nblocks
);
430 return ERR_PTR(-ENOMEM
);
432 handle_t
*rsv_handle
;
434 rsv_handle
= new_handle(rsv_blocks
);
436 jbd2_free_handle(handle
);
437 return ERR_PTR(-ENOMEM
);
439 rsv_handle
->h_reserved
= 1;
440 rsv_handle
->h_journal
= journal
;
441 handle
->h_rsv_handle
= rsv_handle
;
444 err
= start_this_handle(journal
, handle
, gfp_mask
);
446 if (handle
->h_rsv_handle
)
447 jbd2_free_handle(handle
->h_rsv_handle
);
448 jbd2_free_handle(handle
);
451 handle
->h_type
= type
;
452 handle
->h_line_no
= line_no
;
453 trace_jbd2_handle_start(journal
->j_fs_dev
->bd_dev
,
454 handle
->h_transaction
->t_tid
, type
,
459 EXPORT_SYMBOL(jbd2__journal_start
);
463 * handle_t *jbd2_journal_start() - Obtain a new handle.
464 * @journal: Journal to start transaction on.
465 * @nblocks: number of block buffer we might modify
467 * We make sure that the transaction can guarantee at least nblocks of
468 * modified buffers in the log. We block until the log can guarantee
469 * that much space. Additionally, if rsv_blocks > 0, we also create another
470 * handle with rsv_blocks reserved blocks in the journal. This handle is
471 * is stored in h_rsv_handle. It is not attached to any particular transaction
472 * and thus doesn't block transaction commit. If the caller uses this reserved
473 * handle, it has to set h_rsv_handle to NULL as otherwise jbd2_journal_stop()
474 * on the parent handle will dispose the reserved one. Reserved handle has to
475 * be converted to a normal handle using jbd2_journal_start_reserved() before
478 * Return a pointer to a newly allocated handle, or an ERR_PTR() value
481 handle_t
*jbd2_journal_start(journal_t
*journal
, int nblocks
)
483 return jbd2__journal_start(journal
, nblocks
, 0, GFP_NOFS
, 0, 0);
485 EXPORT_SYMBOL(jbd2_journal_start
);
487 void jbd2_journal_free_reserved(handle_t
*handle
)
489 journal_t
*journal
= handle
->h_journal
;
491 WARN_ON(!handle
->h_reserved
);
492 sub_reserved_credits(journal
, handle
->h_buffer_credits
);
493 jbd2_free_handle(handle
);
495 EXPORT_SYMBOL(jbd2_journal_free_reserved
);
498 * int jbd2_journal_start_reserved() - start reserved handle
499 * @handle: handle to start
500 * @type: for handle statistics
501 * @line_no: for handle statistics
503 * Start handle that has been previously reserved with jbd2_journal_reserve().
504 * This attaches @handle to the running transaction (or creates one if there's
505 * not transaction running). Unlike jbd2_journal_start() this function cannot
506 * block on journal commit, checkpointing, or similar stuff. It can block on
507 * memory allocation or frozen journal though.
509 * Return 0 on success, non-zero on error - handle is freed in that case.
511 int jbd2_journal_start_reserved(handle_t
*handle
, unsigned int type
,
512 unsigned int line_no
)
514 journal_t
*journal
= handle
->h_journal
;
517 if (WARN_ON(!handle
->h_reserved
)) {
518 /* Someone passed in normal handle? Just stop it. */
519 jbd2_journal_stop(handle
);
523 * Usefulness of mixing of reserved and unreserved handles is
524 * questionable. So far nobody seems to need it so just error out.
526 if (WARN_ON(current
->journal_info
)) {
527 jbd2_journal_free_reserved(handle
);
531 handle
->h_journal
= NULL
;
533 * GFP_NOFS is here because callers are likely from writeback or
534 * similarly constrained call sites
536 ret
= start_this_handle(journal
, handle
, GFP_NOFS
);
538 handle
->h_journal
= journal
;
539 jbd2_journal_free_reserved(handle
);
542 handle
->h_type
= type
;
543 handle
->h_line_no
= line_no
;
546 EXPORT_SYMBOL(jbd2_journal_start_reserved
);
549 * int jbd2_journal_extend() - extend buffer credits.
550 * @handle: handle to 'extend'
551 * @nblocks: nr blocks to try to extend by.
553 * Some transactions, such as large extends and truncates, can be done
554 * atomically all at once or in several stages. The operation requests
555 * a credit for a number of buffer modifications in advance, but can
556 * extend its credit if it needs more.
558 * jbd2_journal_extend tries to give the running handle more buffer credits.
559 * It does not guarantee that allocation - this is a best-effort only.
560 * The calling process MUST be able to deal cleanly with a failure to
563 * Return 0 on success, non-zero on failure.
565 * return code < 0 implies an error
566 * return code > 0 implies normal transaction-full status.
568 int jbd2_journal_extend(handle_t
*handle
, int nblocks
)
570 transaction_t
*transaction
= handle
->h_transaction
;
575 if (is_handle_aborted(handle
))
577 journal
= transaction
->t_journal
;
581 read_lock(&journal
->j_state_lock
);
583 /* Don't extend a locked-down transaction! */
584 if (transaction
->t_state
!= T_RUNNING
) {
585 jbd_debug(3, "denied handle %p %d blocks: "
586 "transaction not running\n", handle
, nblocks
);
590 spin_lock(&transaction
->t_handle_lock
);
591 wanted
= atomic_add_return(nblocks
,
592 &transaction
->t_outstanding_credits
);
594 if (wanted
> journal
->j_max_transaction_buffers
) {
595 jbd_debug(3, "denied handle %p %d blocks: "
596 "transaction too large\n", handle
, nblocks
);
597 atomic_sub(nblocks
, &transaction
->t_outstanding_credits
);
601 if (wanted
+ (wanted
>> JBD2_CONTROL_BLOCKS_SHIFT
) >
602 jbd2_log_space_left(journal
)) {
603 jbd_debug(3, "denied handle %p %d blocks: "
604 "insufficient log space\n", handle
, nblocks
);
605 atomic_sub(nblocks
, &transaction
->t_outstanding_credits
);
609 trace_jbd2_handle_extend(journal
->j_fs_dev
->bd_dev
,
611 handle
->h_type
, handle
->h_line_no
,
612 handle
->h_buffer_credits
,
615 handle
->h_buffer_credits
+= nblocks
;
616 handle
->h_requested_credits
+= nblocks
;
619 jbd_debug(3, "extended handle %p by %d\n", handle
, nblocks
);
621 spin_unlock(&transaction
->t_handle_lock
);
623 read_unlock(&journal
->j_state_lock
);
629 * int jbd2_journal_restart() - restart a handle .
630 * @handle: handle to restart
631 * @nblocks: nr credits requested
632 * @gfp_mask: memory allocation flags (for start_this_handle)
634 * Restart a handle for a multi-transaction filesystem
637 * If the jbd2_journal_extend() call above fails to grant new buffer credits
638 * to a running handle, a call to jbd2_journal_restart will commit the
639 * handle's transaction so far and reattach the handle to a new
640 * transaction capable of guaranteeing the requested number of
641 * credits. We preserve reserved handle if there's any attached to the
644 int jbd2__journal_restart(handle_t
*handle
, int nblocks
, gfp_t gfp_mask
)
646 transaction_t
*transaction
= handle
->h_transaction
;
649 int need_to_start
, ret
;
651 /* If we've had an abort of any type, don't even think about
652 * actually doing the restart! */
653 if (is_handle_aborted(handle
))
655 journal
= transaction
->t_journal
;
658 * First unlink the handle from its current transaction, and start the
661 J_ASSERT(atomic_read(&transaction
->t_updates
) > 0);
662 J_ASSERT(journal_current_handle() == handle
);
664 read_lock(&journal
->j_state_lock
);
665 spin_lock(&transaction
->t_handle_lock
);
666 atomic_sub(handle
->h_buffer_credits
,
667 &transaction
->t_outstanding_credits
);
668 if (handle
->h_rsv_handle
) {
669 sub_reserved_credits(journal
,
670 handle
->h_rsv_handle
->h_buffer_credits
);
672 if (atomic_dec_and_test(&transaction
->t_updates
))
673 wake_up(&journal
->j_wait_updates
);
674 tid
= transaction
->t_tid
;
675 spin_unlock(&transaction
->t_handle_lock
);
676 handle
->h_transaction
= NULL
;
677 current
->journal_info
= NULL
;
679 jbd_debug(2, "restarting handle %p\n", handle
);
680 need_to_start
= !tid_geq(journal
->j_commit_request
, tid
);
681 read_unlock(&journal
->j_state_lock
);
683 jbd2_log_start_commit(journal
, tid
);
685 rwsem_release(&journal
->j_trans_commit_map
, 1, _THIS_IP_
);
686 handle
->h_buffer_credits
= nblocks
;
688 * Restore the original nofs context because the journal restart
689 * is basically the same thing as journal stop and start.
690 * start_this_handle will start a new nofs context.
692 memalloc_nofs_restore(handle
->saved_alloc_context
);
693 ret
= start_this_handle(journal
, handle
, gfp_mask
);
696 EXPORT_SYMBOL(jbd2__journal_restart
);
699 int jbd2_journal_restart(handle_t
*handle
, int nblocks
)
701 return jbd2__journal_restart(handle
, nblocks
, GFP_NOFS
);
703 EXPORT_SYMBOL(jbd2_journal_restart
);
706 * void jbd2_journal_lock_updates () - establish a transaction barrier.
707 * @journal: Journal to establish a barrier on.
709 * This locks out any further updates from being started, and blocks
710 * until all existing updates have completed, returning only once the
711 * journal is in a quiescent state with no updates running.
713 * The journal lock should not be held on entry.
715 void jbd2_journal_lock_updates(journal_t
*journal
)
719 jbd2_might_wait_for_commit(journal
);
721 write_lock(&journal
->j_state_lock
);
722 ++journal
->j_barrier_count
;
724 /* Wait until there are no reserved handles */
725 if (atomic_read(&journal
->j_reserved_credits
)) {
726 write_unlock(&journal
->j_state_lock
);
727 wait_event(journal
->j_wait_reserved
,
728 atomic_read(&journal
->j_reserved_credits
) == 0);
729 write_lock(&journal
->j_state_lock
);
732 /* Wait until there are no running updates */
734 transaction_t
*transaction
= journal
->j_running_transaction
;
739 spin_lock(&transaction
->t_handle_lock
);
740 prepare_to_wait(&journal
->j_wait_updates
, &wait
,
741 TASK_UNINTERRUPTIBLE
);
742 if (!atomic_read(&transaction
->t_updates
)) {
743 spin_unlock(&transaction
->t_handle_lock
);
744 finish_wait(&journal
->j_wait_updates
, &wait
);
747 spin_unlock(&transaction
->t_handle_lock
);
748 write_unlock(&journal
->j_state_lock
);
750 finish_wait(&journal
->j_wait_updates
, &wait
);
751 write_lock(&journal
->j_state_lock
);
753 write_unlock(&journal
->j_state_lock
);
756 * We have now established a barrier against other normal updates, but
757 * we also need to barrier against other jbd2_journal_lock_updates() calls
758 * to make sure that we serialise special journal-locked operations
761 mutex_lock(&journal
->j_barrier
);
765 * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier
766 * @journal: Journal to release the barrier on.
768 * Release a transaction barrier obtained with jbd2_journal_lock_updates().
770 * Should be called without the journal lock held.
772 void jbd2_journal_unlock_updates (journal_t
*journal
)
774 J_ASSERT(journal
->j_barrier_count
!= 0);
776 mutex_unlock(&journal
->j_barrier
);
777 write_lock(&journal
->j_state_lock
);
778 --journal
->j_barrier_count
;
779 write_unlock(&journal
->j_state_lock
);
780 wake_up(&journal
->j_wait_transaction_locked
);
783 static void warn_dirty_buffer(struct buffer_head
*bh
)
786 "JBD2: Spotted dirty metadata buffer (dev = %pg, blocknr = %llu). "
787 "There's a risk of filesystem corruption in case of system "
789 bh
->b_bdev
, (unsigned long long)bh
->b_blocknr
);
792 /* Call t_frozen trigger and copy buffer data into jh->b_frozen_data. */
793 static void jbd2_freeze_jh_data(struct journal_head
*jh
)
798 struct buffer_head
*bh
= jh2bh(jh
);
800 J_EXPECT_JH(jh
, buffer_uptodate(bh
), "Possible IO failure.\n");
802 offset
= offset_in_page(bh
->b_data
);
803 source
= kmap_atomic(page
);
804 /* Fire data frozen trigger just before we copy the data */
805 jbd2_buffer_frozen_trigger(jh
, source
+ offset
, jh
->b_triggers
);
806 memcpy(jh
->b_frozen_data
, source
+ offset
, bh
->b_size
);
807 kunmap_atomic(source
);
810 * Now that the frozen data is saved off, we need to store any matching
813 jh
->b_frozen_triggers
= jh
->b_triggers
;
817 * If the buffer is already part of the current transaction, then there
818 * is nothing we need to do. If it is already part of a prior
819 * transaction which we are still committing to disk, then we need to
820 * make sure that we do not overwrite the old copy: we do copy-out to
821 * preserve the copy going to disk. We also account the buffer against
822 * the handle's metadata buffer credits (unless the buffer is already
823 * part of the transaction, that is).
827 do_get_write_access(handle_t
*handle
, struct journal_head
*jh
,
830 struct buffer_head
*bh
;
831 transaction_t
*transaction
= handle
->h_transaction
;
834 char *frozen_buffer
= NULL
;
835 unsigned long start_lock
, time_lock
;
837 if (is_handle_aborted(handle
))
839 journal
= transaction
->t_journal
;
841 jbd_debug(5, "journal_head %p, force_copy %d\n", jh
, force_copy
);
843 JBUFFER_TRACE(jh
, "entry");
847 /* @@@ Need to check for errors here at some point. */
849 start_lock
= jiffies
;
851 jbd_lock_bh_state(bh
);
853 /* If it takes too long to lock the buffer, trace it */
854 time_lock
= jbd2_time_diff(start_lock
, jiffies
);
855 if (time_lock
> HZ
/10)
856 trace_jbd2_lock_buffer_stall(bh
->b_bdev
->bd_dev
,
857 jiffies_to_msecs(time_lock
));
859 /* We now hold the buffer lock so it is safe to query the buffer
860 * state. Is the buffer dirty?
862 * If so, there are two possibilities. The buffer may be
863 * non-journaled, and undergoing a quite legitimate writeback.
864 * Otherwise, it is journaled, and we don't expect dirty buffers
865 * in that state (the buffers should be marked JBD_Dirty
866 * instead.) So either the IO is being done under our own
867 * control and this is a bug, or it's a third party IO such as
868 * dump(8) (which may leave the buffer scheduled for read ---
869 * ie. locked but not dirty) or tune2fs (which may actually have
870 * the buffer dirtied, ugh.) */
872 if (buffer_dirty(bh
)) {
874 * First question: is this buffer already part of the current
875 * transaction or the existing committing transaction?
877 if (jh
->b_transaction
) {
879 jh
->b_transaction
== transaction
||
881 journal
->j_committing_transaction
);
882 if (jh
->b_next_transaction
)
883 J_ASSERT_JH(jh
, jh
->b_next_transaction
==
885 warn_dirty_buffer(bh
);
888 * In any case we need to clean the dirty flag and we must
889 * do it under the buffer lock to be sure we don't race
890 * with running write-out.
892 JBUFFER_TRACE(jh
, "Journalling dirty buffer");
893 clear_buffer_dirty(bh
);
894 set_buffer_jbddirty(bh
);
900 if (is_handle_aborted(handle
)) {
901 jbd_unlock_bh_state(bh
);
907 * The buffer is already part of this transaction if b_transaction or
908 * b_next_transaction points to it
910 if (jh
->b_transaction
== transaction
||
911 jh
->b_next_transaction
== transaction
)
915 * this is the first time this transaction is touching this buffer,
916 * reset the modified flag
921 * If the buffer is not journaled right now, we need to make sure it
922 * doesn't get written to disk before the caller actually commits the
925 if (!jh
->b_transaction
) {
926 JBUFFER_TRACE(jh
, "no transaction");
927 J_ASSERT_JH(jh
, !jh
->b_next_transaction
);
928 JBUFFER_TRACE(jh
, "file as BJ_Reserved");
930 * Make sure all stores to jh (b_modified, b_frozen_data) are
931 * visible before attaching it to the running transaction.
932 * Paired with barrier in jbd2_write_access_granted()
935 spin_lock(&journal
->j_list_lock
);
936 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Reserved
);
937 spin_unlock(&journal
->j_list_lock
);
941 * If there is already a copy-out version of this buffer, then we don't
942 * need to make another one
944 if (jh
->b_frozen_data
) {
945 JBUFFER_TRACE(jh
, "has frozen data");
946 J_ASSERT_JH(jh
, jh
->b_next_transaction
== NULL
);
950 JBUFFER_TRACE(jh
, "owned by older transaction");
951 J_ASSERT_JH(jh
, jh
->b_next_transaction
== NULL
);
952 J_ASSERT_JH(jh
, jh
->b_transaction
== journal
->j_committing_transaction
);
955 * There is one case we have to be very careful about. If the
956 * committing transaction is currently writing this buffer out to disk
957 * and has NOT made a copy-out, then we cannot modify the buffer
958 * contents at all right now. The essence of copy-out is that it is
959 * the extra copy, not the primary copy, which gets journaled. If the
960 * primary copy is already going to disk then we cannot do copy-out
963 if (buffer_shadow(bh
)) {
964 JBUFFER_TRACE(jh
, "on shadow: sleep");
965 jbd_unlock_bh_state(bh
);
966 wait_on_bit_io(&bh
->b_state
, BH_Shadow
, TASK_UNINTERRUPTIBLE
);
971 * Only do the copy if the currently-owning transaction still needs it.
972 * If buffer isn't on BJ_Metadata list, the committing transaction is
973 * past that stage (here we use the fact that BH_Shadow is set under
974 * bh_state lock together with refiling to BJ_Shadow list and at this
975 * point we know the buffer doesn't have BH_Shadow set).
977 * Subtle point, though: if this is a get_undo_access, then we will be
978 * relying on the frozen_data to contain the new value of the
979 * committed_data record after the transaction, so we HAVE to force the
980 * frozen_data copy in that case.
982 if (jh
->b_jlist
== BJ_Metadata
|| force_copy
) {
983 JBUFFER_TRACE(jh
, "generate frozen data");
984 if (!frozen_buffer
) {
985 JBUFFER_TRACE(jh
, "allocate memory for buffer");
986 jbd_unlock_bh_state(bh
);
987 frozen_buffer
= jbd2_alloc(jh2bh(jh
)->b_size
,
988 GFP_NOFS
| __GFP_NOFAIL
);
991 jh
->b_frozen_data
= frozen_buffer
;
992 frozen_buffer
= NULL
;
993 jbd2_freeze_jh_data(jh
);
997 * Make sure all stores to jh (b_modified, b_frozen_data) are visible
998 * before attaching it to the running transaction. Paired with barrier
999 * in jbd2_write_access_granted()
1002 jh
->b_next_transaction
= transaction
;
1005 jbd_unlock_bh_state(bh
);
1008 * If we are about to journal a buffer, then any revoke pending on it is
1011 jbd2_journal_cancel_revoke(handle
, jh
);
1014 if (unlikely(frozen_buffer
)) /* It's usually NULL */
1015 jbd2_free(frozen_buffer
, bh
->b_size
);
1017 JBUFFER_TRACE(jh
, "exit");
1021 /* Fast check whether buffer is already attached to the required transaction */
1022 static bool jbd2_write_access_granted(handle_t
*handle
, struct buffer_head
*bh
,
1025 struct journal_head
*jh
;
1028 /* Dirty buffers require special handling... */
1029 if (buffer_dirty(bh
))
1033 * RCU protects us from dereferencing freed pages. So the checks we do
1034 * are guaranteed not to oops. However the jh slab object can get freed
1035 * & reallocated while we work with it. So we have to be careful. When
1036 * we see jh attached to the running transaction, we know it must stay
1037 * so until the transaction is committed. Thus jh won't be freed and
1038 * will be attached to the same bh while we run. However it can
1039 * happen jh gets freed, reallocated, and attached to the transaction
1040 * just after we get pointer to it from bh. So we have to be careful
1041 * and recheck jh still belongs to our bh before we return success.
1044 if (!buffer_jbd(bh
))
1046 /* This should be bh2jh() but that doesn't work with inline functions */
1047 jh
= READ_ONCE(bh
->b_private
);
1050 /* For undo access buffer must have data copied */
1051 if (undo
&& !jh
->b_committed_data
)
1053 if (jh
->b_transaction
!= handle
->h_transaction
&&
1054 jh
->b_next_transaction
!= handle
->h_transaction
)
1057 * There are two reasons for the barrier here:
1058 * 1) Make sure to fetch b_bh after we did previous checks so that we
1059 * detect when jh went through free, realloc, attach to transaction
1060 * while we were checking. Paired with implicit barrier in that path.
1061 * 2) So that access to bh done after jbd2_write_access_granted()
1062 * doesn't get reordered and see inconsistent state of concurrent
1063 * do_get_write_access().
1066 if (unlikely(jh
->b_bh
!= bh
))
1075 * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
1076 * @handle: transaction to add buffer modifications to
1077 * @bh: bh to be used for metadata writes
1079 * Returns: error code or 0 on success.
1081 * In full data journalling mode the buffer may be of type BJ_AsyncData,
1082 * because we're ``write()ing`` a buffer which is also part of a shared mapping.
1085 int jbd2_journal_get_write_access(handle_t
*handle
, struct buffer_head
*bh
)
1087 struct journal_head
*jh
;
1090 if (jbd2_write_access_granted(handle
, bh
, false))
1093 jh
= jbd2_journal_add_journal_head(bh
);
1094 /* We do not want to get caught playing with fields which the
1095 * log thread also manipulates. Make sure that the buffer
1096 * completes any outstanding IO before proceeding. */
1097 rc
= do_get_write_access(handle
, jh
, 0);
1098 jbd2_journal_put_journal_head(jh
);
1104 * When the user wants to journal a newly created buffer_head
1105 * (ie. getblk() returned a new buffer and we are going to populate it
1106 * manually rather than reading off disk), then we need to keep the
1107 * buffer_head locked until it has been completely filled with new
1108 * data. In this case, we should be able to make the assertion that
1109 * the bh is not already part of an existing transaction.
1111 * The buffer should already be locked by the caller by this point.
1112 * There is no lock ranking violation: it was a newly created,
1113 * unlocked buffer beforehand. */
1116 * int jbd2_journal_get_create_access () - notify intent to use newly created bh
1117 * @handle: transaction to new buffer to
1120 * Call this if you create a new bh.
1122 int jbd2_journal_get_create_access(handle_t
*handle
, struct buffer_head
*bh
)
1124 transaction_t
*transaction
= handle
->h_transaction
;
1126 struct journal_head
*jh
= jbd2_journal_add_journal_head(bh
);
1129 jbd_debug(5, "journal_head %p\n", jh
);
1131 if (is_handle_aborted(handle
))
1133 journal
= transaction
->t_journal
;
1136 JBUFFER_TRACE(jh
, "entry");
1138 * The buffer may already belong to this transaction due to pre-zeroing
1139 * in the filesystem's new_block code. It may also be on the previous,
1140 * committing transaction's lists, but it HAS to be in Forget state in
1141 * that case: the transaction must have deleted the buffer for it to be
1144 jbd_lock_bh_state(bh
);
1145 J_ASSERT_JH(jh
, (jh
->b_transaction
== transaction
||
1146 jh
->b_transaction
== NULL
||
1147 (jh
->b_transaction
== journal
->j_committing_transaction
&&
1148 jh
->b_jlist
== BJ_Forget
)));
1150 J_ASSERT_JH(jh
, jh
->b_next_transaction
== NULL
);
1151 J_ASSERT_JH(jh
, buffer_locked(jh2bh(jh
)));
1153 if (jh
->b_transaction
== NULL
) {
1155 * Previous jbd2_journal_forget() could have left the buffer
1156 * with jbddirty bit set because it was being committed. When
1157 * the commit finished, we've filed the buffer for
1158 * checkpointing and marked it dirty. Now we are reallocating
1159 * the buffer so the transaction freeing it must have
1160 * committed and so it's safe to clear the dirty bit.
1162 clear_buffer_dirty(jh2bh(jh
));
1163 /* first access by this transaction */
1166 JBUFFER_TRACE(jh
, "file as BJ_Reserved");
1167 spin_lock(&journal
->j_list_lock
);
1168 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Reserved
);
1169 spin_unlock(&journal
->j_list_lock
);
1170 } else if (jh
->b_transaction
== journal
->j_committing_transaction
) {
1171 /* first access by this transaction */
1174 JBUFFER_TRACE(jh
, "set next transaction");
1175 spin_lock(&journal
->j_list_lock
);
1176 jh
->b_next_transaction
= transaction
;
1177 spin_unlock(&journal
->j_list_lock
);
1179 jbd_unlock_bh_state(bh
);
1182 * akpm: I added this. ext3_alloc_branch can pick up new indirect
1183 * blocks which contain freed but then revoked metadata. We need
1184 * to cancel the revoke in case we end up freeing it yet again
1185 * and the reallocating as data - this would cause a second revoke,
1186 * which hits an assertion error.
1188 JBUFFER_TRACE(jh
, "cancelling revoke");
1189 jbd2_journal_cancel_revoke(handle
, jh
);
1191 jbd2_journal_put_journal_head(jh
);
1196 * int jbd2_journal_get_undo_access() - Notify intent to modify metadata with
1197 * non-rewindable consequences
1198 * @handle: transaction
1199 * @bh: buffer to undo
1201 * Sometimes there is a need to distinguish between metadata which has
1202 * been committed to disk and that which has not. The ext3fs code uses
1203 * this for freeing and allocating space, we have to make sure that we
1204 * do not reuse freed space until the deallocation has been committed,
1205 * since if we overwrote that space we would make the delete
1206 * un-rewindable in case of a crash.
1208 * To deal with that, jbd2_journal_get_undo_access requests write access to a
1209 * buffer for parts of non-rewindable operations such as delete
1210 * operations on the bitmaps. The journaling code must keep a copy of
1211 * the buffer's contents prior to the undo_access call until such time
1212 * as we know that the buffer has definitely been committed to disk.
1214 * We never need to know which transaction the committed data is part
1215 * of, buffers touched here are guaranteed to be dirtied later and so
1216 * will be committed to a new transaction in due course, at which point
1217 * we can discard the old committed data pointer.
1219 * Returns error number or 0 on success.
1221 int jbd2_journal_get_undo_access(handle_t
*handle
, struct buffer_head
*bh
)
1224 struct journal_head
*jh
;
1225 char *committed_data
= NULL
;
1227 JBUFFER_TRACE(jh
, "entry");
1228 if (jbd2_write_access_granted(handle
, bh
, true))
1231 jh
= jbd2_journal_add_journal_head(bh
);
1233 * Do this first --- it can drop the journal lock, so we want to
1234 * make sure that obtaining the committed_data is done
1235 * atomically wrt. completion of any outstanding commits.
1237 err
= do_get_write_access(handle
, jh
, 1);
1242 if (!jh
->b_committed_data
)
1243 committed_data
= jbd2_alloc(jh2bh(jh
)->b_size
,
1244 GFP_NOFS
|__GFP_NOFAIL
);
1246 jbd_lock_bh_state(bh
);
1247 if (!jh
->b_committed_data
) {
1248 /* Copy out the current buffer contents into the
1249 * preserved, committed copy. */
1250 JBUFFER_TRACE(jh
, "generate b_committed data");
1251 if (!committed_data
) {
1252 jbd_unlock_bh_state(bh
);
1256 jh
->b_committed_data
= committed_data
;
1257 committed_data
= NULL
;
1258 memcpy(jh
->b_committed_data
, bh
->b_data
, bh
->b_size
);
1260 jbd_unlock_bh_state(bh
);
1262 jbd2_journal_put_journal_head(jh
);
1263 if (unlikely(committed_data
))
1264 jbd2_free(committed_data
, bh
->b_size
);
1269 * void jbd2_journal_set_triggers() - Add triggers for commit writeout
1270 * @bh: buffer to trigger on
1271 * @type: struct jbd2_buffer_trigger_type containing the trigger(s).
1273 * Set any triggers on this journal_head. This is always safe, because
1274 * triggers for a committing buffer will be saved off, and triggers for
1275 * a running transaction will match the buffer in that transaction.
1277 * Call with NULL to clear the triggers.
1279 void jbd2_journal_set_triggers(struct buffer_head
*bh
,
1280 struct jbd2_buffer_trigger_type
*type
)
1282 struct journal_head
*jh
= jbd2_journal_grab_journal_head(bh
);
1286 jh
->b_triggers
= type
;
1287 jbd2_journal_put_journal_head(jh
);
1290 void jbd2_buffer_frozen_trigger(struct journal_head
*jh
, void *mapped_data
,
1291 struct jbd2_buffer_trigger_type
*triggers
)
1293 struct buffer_head
*bh
= jh2bh(jh
);
1295 if (!triggers
|| !triggers
->t_frozen
)
1298 triggers
->t_frozen(triggers
, bh
, mapped_data
, bh
->b_size
);
1301 void jbd2_buffer_abort_trigger(struct journal_head
*jh
,
1302 struct jbd2_buffer_trigger_type
*triggers
)
1304 if (!triggers
|| !triggers
->t_abort
)
1307 triggers
->t_abort(triggers
, jh2bh(jh
));
1311 * int jbd2_journal_dirty_metadata() - mark a buffer as containing dirty metadata
1312 * @handle: transaction to add buffer to.
1313 * @bh: buffer to mark
1315 * mark dirty metadata which needs to be journaled as part of the current
1318 * The buffer must have previously had jbd2_journal_get_write_access()
1319 * called so that it has a valid journal_head attached to the buffer
1322 * The buffer is placed on the transaction's metadata list and is marked
1323 * as belonging to the transaction.
1325 * Returns error number or 0 on success.
1327 * Special care needs to be taken if the buffer already belongs to the
1328 * current committing transaction (in which case we should have frozen
1329 * data present for that commit). In that case, we don't relink the
1330 * buffer: that only gets done when the old transaction finally
1331 * completes its commit.
1333 int jbd2_journal_dirty_metadata(handle_t
*handle
, struct buffer_head
*bh
)
1335 transaction_t
*transaction
= handle
->h_transaction
;
1337 struct journal_head
*jh
;
1340 if (is_handle_aborted(handle
))
1342 if (!buffer_jbd(bh
)) {
1347 * We don't grab jh reference here since the buffer must be part
1348 * of the running transaction.
1352 * This and the following assertions are unreliable since we may see jh
1353 * in inconsistent state unless we grab bh_state lock. But this is
1354 * crucial to catch bugs so let's do a reliable check until the
1355 * lockless handling is fully proven.
1357 if (jh
->b_transaction
!= transaction
&&
1358 jh
->b_next_transaction
!= transaction
) {
1359 jbd_lock_bh_state(bh
);
1360 J_ASSERT_JH(jh
, jh
->b_transaction
== transaction
||
1361 jh
->b_next_transaction
== transaction
);
1362 jbd_unlock_bh_state(bh
);
1364 if (jh
->b_modified
== 1) {
1365 /* If it's in our transaction it must be in BJ_Metadata list. */
1366 if (jh
->b_transaction
== transaction
&&
1367 jh
->b_jlist
!= BJ_Metadata
) {
1368 jbd_lock_bh_state(bh
);
1369 J_ASSERT_JH(jh
, jh
->b_transaction
!= transaction
||
1370 jh
->b_jlist
== BJ_Metadata
);
1371 jbd_unlock_bh_state(bh
);
1376 journal
= transaction
->t_journal
;
1377 jbd_debug(5, "journal_head %p\n", jh
);
1378 JBUFFER_TRACE(jh
, "entry");
1380 jbd_lock_bh_state(bh
);
1382 if (jh
->b_modified
== 0) {
1384 * This buffer's got modified and becoming part
1385 * of the transaction. This needs to be done
1386 * once a transaction -bzzz
1389 if (handle
->h_buffer_credits
<= 0) {
1393 handle
->h_buffer_credits
--;
1397 * fastpath, to avoid expensive locking. If this buffer is already
1398 * on the running transaction's metadata list there is nothing to do.
1399 * Nobody can take it off again because there is a handle open.
1400 * I _think_ we're OK here with SMP barriers - a mistaken decision will
1401 * result in this test being false, so we go in and take the locks.
1403 if (jh
->b_transaction
== transaction
&& jh
->b_jlist
== BJ_Metadata
) {
1404 JBUFFER_TRACE(jh
, "fastpath");
1405 if (unlikely(jh
->b_transaction
!=
1406 journal
->j_running_transaction
)) {
1407 printk(KERN_ERR
"JBD2: %s: "
1408 "jh->b_transaction (%llu, %p, %u) != "
1409 "journal->j_running_transaction (%p, %u)\n",
1411 (unsigned long long) bh
->b_blocknr
,
1413 jh
->b_transaction
? jh
->b_transaction
->t_tid
: 0,
1414 journal
->j_running_transaction
,
1415 journal
->j_running_transaction
?
1416 journal
->j_running_transaction
->t_tid
: 0);
1422 set_buffer_jbddirty(bh
);
1425 * Metadata already on the current transaction list doesn't
1426 * need to be filed. Metadata on another transaction's list must
1427 * be committing, and will be refiled once the commit completes:
1428 * leave it alone for now.
1430 if (jh
->b_transaction
!= transaction
) {
1431 JBUFFER_TRACE(jh
, "already on other transaction");
1432 if (unlikely(((jh
->b_transaction
!=
1433 journal
->j_committing_transaction
)) ||
1434 (jh
->b_next_transaction
!= transaction
))) {
1435 printk(KERN_ERR
"jbd2_journal_dirty_metadata: %s: "
1436 "bad jh for block %llu: "
1437 "transaction (%p, %u), "
1438 "jh->b_transaction (%p, %u), "
1439 "jh->b_next_transaction (%p, %u), jlist %u\n",
1441 (unsigned long long) bh
->b_blocknr
,
1442 transaction
, transaction
->t_tid
,
1445 jh
->b_transaction
->t_tid
: 0,
1446 jh
->b_next_transaction
,
1447 jh
->b_next_transaction
?
1448 jh
->b_next_transaction
->t_tid
: 0,
1453 /* And this case is illegal: we can't reuse another
1454 * transaction's data buffer, ever. */
1458 /* That test should have eliminated the following case: */
1459 J_ASSERT_JH(jh
, jh
->b_frozen_data
== NULL
);
1461 JBUFFER_TRACE(jh
, "file as BJ_Metadata");
1462 spin_lock(&journal
->j_list_lock
);
1463 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Metadata
);
1464 spin_unlock(&journal
->j_list_lock
);
1466 jbd_unlock_bh_state(bh
);
1468 JBUFFER_TRACE(jh
, "exit");
1473 * void jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1474 * @handle: transaction handle
1475 * @bh: bh to 'forget'
1477 * We can only do the bforget if there are no commits pending against the
1478 * buffer. If the buffer is dirty in the current running transaction we
1479 * can safely unlink it.
1481 * bh may not be a journalled buffer at all - it may be a non-JBD
1482 * buffer which came off the hashtable. Check for this.
1484 * Decrements bh->b_count by one.
1486 * Allow this call even if the handle has aborted --- it may be part of
1487 * the caller's cleanup after an abort.
1489 int jbd2_journal_forget (handle_t
*handle
, struct buffer_head
*bh
)
1491 transaction_t
*transaction
= handle
->h_transaction
;
1493 struct journal_head
*jh
;
1494 int drop_reserve
= 0;
1496 int was_modified
= 0;
1498 if (is_handle_aborted(handle
))
1500 journal
= transaction
->t_journal
;
1502 BUFFER_TRACE(bh
, "entry");
1504 jbd_lock_bh_state(bh
);
1506 if (!buffer_jbd(bh
))
1510 /* Critical error: attempting to delete a bitmap buffer, maybe?
1511 * Don't do any jbd operations, and return an error. */
1512 if (!J_EXPECT_JH(jh
, !jh
->b_committed_data
,
1513 "inconsistent data on disk")) {
1518 /* keep track of whether or not this transaction modified us */
1519 was_modified
= jh
->b_modified
;
1522 * The buffer's going from the transaction, we must drop
1523 * all references -bzzz
1527 if (jh
->b_transaction
== transaction
) {
1528 J_ASSERT_JH(jh
, !jh
->b_frozen_data
);
1530 /* If we are forgetting a buffer which is already part
1531 * of this transaction, then we can just drop it from
1532 * the transaction immediately. */
1533 clear_buffer_dirty(bh
);
1534 clear_buffer_jbddirty(bh
);
1536 JBUFFER_TRACE(jh
, "belongs to current transaction: unfile");
1539 * we only want to drop a reference if this transaction
1540 * modified the buffer
1546 * We are no longer going to journal this buffer.
1547 * However, the commit of this transaction is still
1548 * important to the buffer: the delete that we are now
1549 * processing might obsolete an old log entry, so by
1550 * committing, we can satisfy the buffer's checkpoint.
1552 * So, if we have a checkpoint on the buffer, we should
1553 * now refile the buffer on our BJ_Forget list so that
1554 * we know to remove the checkpoint after we commit.
1557 spin_lock(&journal
->j_list_lock
);
1558 if (jh
->b_cp_transaction
) {
1559 __jbd2_journal_temp_unlink_buffer(jh
);
1560 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Forget
);
1562 __jbd2_journal_unfile_buffer(jh
);
1563 if (!buffer_jbd(bh
)) {
1564 spin_unlock(&journal
->j_list_lock
);
1565 jbd_unlock_bh_state(bh
);
1570 spin_unlock(&journal
->j_list_lock
);
1571 } else if (jh
->b_transaction
) {
1572 J_ASSERT_JH(jh
, (jh
->b_transaction
==
1573 journal
->j_committing_transaction
));
1574 /* However, if the buffer is still owned by a prior
1575 * (committing) transaction, we can't drop it yet... */
1576 JBUFFER_TRACE(jh
, "belongs to older transaction");
1577 /* ... but we CAN drop it from the new transaction if we
1578 * have also modified it since the original commit. */
1580 if (jh
->b_next_transaction
) {
1581 J_ASSERT(jh
->b_next_transaction
== transaction
);
1582 spin_lock(&journal
->j_list_lock
);
1583 jh
->b_next_transaction
= NULL
;
1584 spin_unlock(&journal
->j_list_lock
);
1587 * only drop a reference if this transaction modified
1596 jbd_unlock_bh_state(bh
);
1600 /* no need to reserve log space for this block -bzzz */
1601 handle
->h_buffer_credits
++;
1607 * int jbd2_journal_stop() - complete a transaction
1608 * @handle: transaction to complete.
1610 * All done for a particular handle.
1612 * There is not much action needed here. We just return any remaining
1613 * buffer credits to the transaction and remove the handle. The only
1614 * complication is that we need to start a commit operation if the
1615 * filesystem is marked for synchronous update.
1617 * jbd2_journal_stop itself will not usually return an error, but it may
1618 * do so in unusual circumstances. In particular, expect it to
1619 * return -EIO if a jbd2_journal_abort has been executed since the
1620 * transaction began.
1622 int jbd2_journal_stop(handle_t
*handle
)
1624 transaction_t
*transaction
= handle
->h_transaction
;
1626 int err
= 0, wait_for_commit
= 0;
1632 * Handle is already detached from the transaction so
1633 * there is nothing to do other than decrease a refcount,
1634 * or free the handle if refcount drops to zero
1636 if (--handle
->h_ref
> 0) {
1637 jbd_debug(4, "h_ref %d -> %d\n", handle
->h_ref
+ 1,
1641 if (handle
->h_rsv_handle
)
1642 jbd2_free_handle(handle
->h_rsv_handle
);
1646 journal
= transaction
->t_journal
;
1648 J_ASSERT(journal_current_handle() == handle
);
1650 if (is_handle_aborted(handle
))
1653 J_ASSERT(atomic_read(&transaction
->t_updates
) > 0);
1655 if (--handle
->h_ref
> 0) {
1656 jbd_debug(4, "h_ref %d -> %d\n", handle
->h_ref
+ 1,
1661 jbd_debug(4, "Handle %p going down\n", handle
);
1662 trace_jbd2_handle_stats(journal
->j_fs_dev
->bd_dev
,
1664 handle
->h_type
, handle
->h_line_no
,
1665 jiffies
- handle
->h_start_jiffies
,
1666 handle
->h_sync
, handle
->h_requested_credits
,
1667 (handle
->h_requested_credits
-
1668 handle
->h_buffer_credits
));
1671 * Implement synchronous transaction batching. If the handle
1672 * was synchronous, don't force a commit immediately. Let's
1673 * yield and let another thread piggyback onto this
1674 * transaction. Keep doing that while new threads continue to
1675 * arrive. It doesn't cost much - we're about to run a commit
1676 * and sleep on IO anyway. Speeds up many-threaded, many-dir
1677 * operations by 30x or more...
1679 * We try and optimize the sleep time against what the
1680 * underlying disk can do, instead of having a static sleep
1681 * time. This is useful for the case where our storage is so
1682 * fast that it is more optimal to go ahead and force a flush
1683 * and wait for the transaction to be committed than it is to
1684 * wait for an arbitrary amount of time for new writers to
1685 * join the transaction. We achieve this by measuring how
1686 * long it takes to commit a transaction, and compare it with
1687 * how long this transaction has been running, and if run time
1688 * < commit time then we sleep for the delta and commit. This
1689 * greatly helps super fast disks that would see slowdowns as
1690 * more threads started doing fsyncs.
1692 * But don't do this if this process was the most recent one
1693 * to perform a synchronous write. We do this to detect the
1694 * case where a single process is doing a stream of sync
1695 * writes. No point in waiting for joiners in that case.
1697 * Setting max_batch_time to 0 disables this completely.
1700 if (handle
->h_sync
&& journal
->j_last_sync_writer
!= pid
&&
1701 journal
->j_max_batch_time
) {
1702 u64 commit_time
, trans_time
;
1704 journal
->j_last_sync_writer
= pid
;
1706 read_lock(&journal
->j_state_lock
);
1707 commit_time
= journal
->j_average_commit_time
;
1708 read_unlock(&journal
->j_state_lock
);
1710 trans_time
= ktime_to_ns(ktime_sub(ktime_get(),
1711 transaction
->t_start_time
));
1713 commit_time
= max_t(u64
, commit_time
,
1714 1000*journal
->j_min_batch_time
);
1715 commit_time
= min_t(u64
, commit_time
,
1716 1000*journal
->j_max_batch_time
);
1718 if (trans_time
< commit_time
) {
1719 ktime_t expires
= ktime_add_ns(ktime_get(),
1721 set_current_state(TASK_UNINTERRUPTIBLE
);
1722 schedule_hrtimeout(&expires
, HRTIMER_MODE_ABS
);
1727 transaction
->t_synchronous_commit
= 1;
1728 current
->journal_info
= NULL
;
1729 atomic_sub(handle
->h_buffer_credits
,
1730 &transaction
->t_outstanding_credits
);
1733 * If the handle is marked SYNC, we need to set another commit
1734 * going! We also want to force a commit if the current
1735 * transaction is occupying too much of the log, or if the
1736 * transaction is too old now.
1738 if (handle
->h_sync
||
1739 (atomic_read(&transaction
->t_outstanding_credits
) >
1740 journal
->j_max_transaction_buffers
) ||
1741 time_after_eq(jiffies
, transaction
->t_expires
)) {
1742 /* Do this even for aborted journals: an abort still
1743 * completes the commit thread, it just doesn't write
1744 * anything to disk. */
1746 jbd_debug(2, "transaction too old, requesting commit for "
1747 "handle %p\n", handle
);
1748 /* This is non-blocking */
1749 jbd2_log_start_commit(journal
, transaction
->t_tid
);
1752 * Special case: JBD2_SYNC synchronous updates require us
1753 * to wait for the commit to complete.
1755 if (handle
->h_sync
&& !(current
->flags
& PF_MEMALLOC
))
1756 wait_for_commit
= 1;
1760 * Once we drop t_updates, if it goes to zero the transaction
1761 * could start committing on us and eventually disappear. So
1762 * once we do this, we must not dereference transaction
1765 tid
= transaction
->t_tid
;
1766 if (atomic_dec_and_test(&transaction
->t_updates
)) {
1767 wake_up(&journal
->j_wait_updates
);
1768 if (journal
->j_barrier_count
)
1769 wake_up(&journal
->j_wait_transaction_locked
);
1772 rwsem_release(&journal
->j_trans_commit_map
, 1, _THIS_IP_
);
1774 if (wait_for_commit
)
1775 err
= jbd2_log_wait_commit(journal
, tid
);
1777 if (handle
->h_rsv_handle
)
1778 jbd2_journal_free_reserved(handle
->h_rsv_handle
);
1781 * Scope of the GFP_NOFS context is over here and so we can restore the
1782 * original alloc context.
1784 memalloc_nofs_restore(handle
->saved_alloc_context
);
1785 jbd2_free_handle(handle
);
1791 * List management code snippets: various functions for manipulating the
1792 * transaction buffer lists.
1797 * Append a buffer to a transaction list, given the transaction's list head
1800 * j_list_lock is held.
1802 * jbd_lock_bh_state(jh2bh(jh)) is held.
1806 __blist_add_buffer(struct journal_head
**list
, struct journal_head
*jh
)
1809 jh
->b_tnext
= jh
->b_tprev
= jh
;
1812 /* Insert at the tail of the list to preserve order */
1813 struct journal_head
*first
= *list
, *last
= first
->b_tprev
;
1815 jh
->b_tnext
= first
;
1816 last
->b_tnext
= first
->b_tprev
= jh
;
1821 * Remove a buffer from a transaction list, given the transaction's list
1824 * Called with j_list_lock held, and the journal may not be locked.
1826 * jbd_lock_bh_state(jh2bh(jh)) is held.
1830 __blist_del_buffer(struct journal_head
**list
, struct journal_head
*jh
)
1833 *list
= jh
->b_tnext
;
1837 jh
->b_tprev
->b_tnext
= jh
->b_tnext
;
1838 jh
->b_tnext
->b_tprev
= jh
->b_tprev
;
1842 * Remove a buffer from the appropriate transaction list.
1844 * Note that this function can *change* the value of
1845 * bh->b_transaction->t_buffers, t_forget, t_shadow_list, t_log_list or
1846 * t_reserved_list. If the caller is holding onto a copy of one of these
1847 * pointers, it could go bad. Generally the caller needs to re-read the
1848 * pointer from the transaction_t.
1850 * Called under j_list_lock.
1852 static void __jbd2_journal_temp_unlink_buffer(struct journal_head
*jh
)
1854 struct journal_head
**list
= NULL
;
1855 transaction_t
*transaction
;
1856 struct buffer_head
*bh
= jh2bh(jh
);
1858 J_ASSERT_JH(jh
, jbd_is_locked_bh_state(bh
));
1859 transaction
= jh
->b_transaction
;
1861 assert_spin_locked(&transaction
->t_journal
->j_list_lock
);
1863 J_ASSERT_JH(jh
, jh
->b_jlist
< BJ_Types
);
1864 if (jh
->b_jlist
!= BJ_None
)
1865 J_ASSERT_JH(jh
, transaction
!= NULL
);
1867 switch (jh
->b_jlist
) {
1871 transaction
->t_nr_buffers
--;
1872 J_ASSERT_JH(jh
, transaction
->t_nr_buffers
>= 0);
1873 list
= &transaction
->t_buffers
;
1876 list
= &transaction
->t_forget
;
1879 list
= &transaction
->t_shadow_list
;
1882 list
= &transaction
->t_reserved_list
;
1886 __blist_del_buffer(list
, jh
);
1887 jh
->b_jlist
= BJ_None
;
1888 if (transaction
&& is_journal_aborted(transaction
->t_journal
))
1889 clear_buffer_jbddirty(bh
);
1890 else if (test_clear_buffer_jbddirty(bh
))
1891 mark_buffer_dirty(bh
); /* Expose it to the VM */
1895 * Remove buffer from all transactions.
1897 * Called with bh_state lock and j_list_lock
1899 * jh and bh may be already freed when this function returns.
1901 static void __jbd2_journal_unfile_buffer(struct journal_head
*jh
)
1903 __jbd2_journal_temp_unlink_buffer(jh
);
1904 jh
->b_transaction
= NULL
;
1905 jbd2_journal_put_journal_head(jh
);
1908 void jbd2_journal_unfile_buffer(journal_t
*journal
, struct journal_head
*jh
)
1910 struct buffer_head
*bh
= jh2bh(jh
);
1912 /* Get reference so that buffer cannot be freed before we unlock it */
1914 jbd_lock_bh_state(bh
);
1915 spin_lock(&journal
->j_list_lock
);
1916 __jbd2_journal_unfile_buffer(jh
);
1917 spin_unlock(&journal
->j_list_lock
);
1918 jbd_unlock_bh_state(bh
);
1923 * Called from jbd2_journal_try_to_free_buffers().
1925 * Called under jbd_lock_bh_state(bh)
1928 __journal_try_to_free_buffer(journal_t
*journal
, struct buffer_head
*bh
)
1930 struct journal_head
*jh
;
1934 if (buffer_locked(bh
) || buffer_dirty(bh
))
1937 if (jh
->b_next_transaction
!= NULL
|| jh
->b_transaction
!= NULL
)
1940 spin_lock(&journal
->j_list_lock
);
1941 if (jh
->b_cp_transaction
!= NULL
) {
1942 /* written-back checkpointed metadata buffer */
1943 JBUFFER_TRACE(jh
, "remove from checkpoint list");
1944 __jbd2_journal_remove_checkpoint(jh
);
1946 spin_unlock(&journal
->j_list_lock
);
1952 * int jbd2_journal_try_to_free_buffers() - try to free page buffers.
1953 * @journal: journal for operation
1954 * @page: to try and free
1955 * @gfp_mask: we use the mask to detect how hard should we try to release
1956 * buffers. If __GFP_DIRECT_RECLAIM and __GFP_FS is set, we wait for commit
1957 * code to release the buffers.
1960 * For all the buffers on this page,
1961 * if they are fully written out ordered data, move them onto BUF_CLEAN
1962 * so try_to_free_buffers() can reap them.
1964 * This function returns non-zero if we wish try_to_free_buffers()
1965 * to be called. We do this if the page is releasable by try_to_free_buffers().
1966 * We also do it if the page has locked or dirty buffers and the caller wants
1967 * us to perform sync or async writeout.
1969 * This complicates JBD locking somewhat. We aren't protected by the
1970 * BKL here. We wish to remove the buffer from its committing or
1971 * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
1973 * This may *change* the value of transaction_t->t_datalist, so anyone
1974 * who looks at t_datalist needs to lock against this function.
1976 * Even worse, someone may be doing a jbd2_journal_dirty_data on this
1977 * buffer. So we need to lock against that. jbd2_journal_dirty_data()
1978 * will come out of the lock with the buffer dirty, which makes it
1979 * ineligible for release here.
1981 * Who else is affected by this? hmm... Really the only contender
1982 * is do_get_write_access() - it could be looking at the buffer while
1983 * journal_try_to_free_buffer() is changing its state. But that
1984 * cannot happen because we never reallocate freed data as metadata
1985 * while the data is part of a transaction. Yes?
1987 * Return 0 on failure, 1 on success
1989 int jbd2_journal_try_to_free_buffers(journal_t
*journal
,
1990 struct page
*page
, gfp_t gfp_mask
)
1992 struct buffer_head
*head
;
1993 struct buffer_head
*bh
;
1996 J_ASSERT(PageLocked(page
));
1998 head
= page_buffers(page
);
2001 struct journal_head
*jh
;
2004 * We take our own ref against the journal_head here to avoid
2005 * having to add tons of locking around each instance of
2006 * jbd2_journal_put_journal_head().
2008 jh
= jbd2_journal_grab_journal_head(bh
);
2012 jbd_lock_bh_state(bh
);
2013 __journal_try_to_free_buffer(journal
, bh
);
2014 jbd2_journal_put_journal_head(jh
);
2015 jbd_unlock_bh_state(bh
);
2018 } while ((bh
= bh
->b_this_page
) != head
);
2020 ret
= try_to_free_buffers(page
);
2027 * This buffer is no longer needed. If it is on an older transaction's
2028 * checkpoint list we need to record it on this transaction's forget list
2029 * to pin this buffer (and hence its checkpointing transaction) down until
2030 * this transaction commits. If the buffer isn't on a checkpoint list, we
2032 * Returns non-zero if JBD no longer has an interest in the buffer.
2034 * Called under j_list_lock.
2036 * Called under jbd_lock_bh_state(bh).
2038 static int __dispose_buffer(struct journal_head
*jh
, transaction_t
*transaction
)
2041 struct buffer_head
*bh
= jh2bh(jh
);
2043 if (jh
->b_cp_transaction
) {
2044 JBUFFER_TRACE(jh
, "on running+cp transaction");
2045 __jbd2_journal_temp_unlink_buffer(jh
);
2047 * We don't want to write the buffer anymore, clear the
2048 * bit so that we don't confuse checks in
2049 * __journal_file_buffer
2051 clear_buffer_dirty(bh
);
2052 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Forget
);
2055 JBUFFER_TRACE(jh
, "on running transaction");
2056 __jbd2_journal_unfile_buffer(jh
);
2062 * jbd2_journal_invalidatepage
2064 * This code is tricky. It has a number of cases to deal with.
2066 * There are two invariants which this code relies on:
2068 * i_size must be updated on disk before we start calling invalidatepage on the
2071 * This is done in ext3 by defining an ext3_setattr method which
2072 * updates i_size before truncate gets going. By maintaining this
2073 * invariant, we can be sure that it is safe to throw away any buffers
2074 * attached to the current transaction: once the transaction commits,
2075 * we know that the data will not be needed.
2077 * Note however that we can *not* throw away data belonging to the
2078 * previous, committing transaction!
2080 * Any disk blocks which *are* part of the previous, committing
2081 * transaction (and which therefore cannot be discarded immediately) are
2082 * not going to be reused in the new running transaction
2084 * The bitmap committed_data images guarantee this: any block which is
2085 * allocated in one transaction and removed in the next will be marked
2086 * as in-use in the committed_data bitmap, so cannot be reused until
2087 * the next transaction to delete the block commits. This means that
2088 * leaving committing buffers dirty is quite safe: the disk blocks
2089 * cannot be reallocated to a different file and so buffer aliasing is
2093 * The above applies mainly to ordered data mode. In writeback mode we
2094 * don't make guarantees about the order in which data hits disk --- in
2095 * particular we don't guarantee that new dirty data is flushed before
2096 * transaction commit --- so it is always safe just to discard data
2097 * immediately in that mode. --sct
2101 * The journal_unmap_buffer helper function returns zero if the buffer
2102 * concerned remains pinned as an anonymous buffer belonging to an older
2105 * We're outside-transaction here. Either or both of j_running_transaction
2106 * and j_committing_transaction may be NULL.
2108 static int journal_unmap_buffer(journal_t
*journal
, struct buffer_head
*bh
,
2111 transaction_t
*transaction
;
2112 struct journal_head
*jh
;
2115 BUFFER_TRACE(bh
, "entry");
2118 * It is safe to proceed here without the j_list_lock because the
2119 * buffers cannot be stolen by try_to_free_buffers as long as we are
2120 * holding the page lock. --sct
2123 if (!buffer_jbd(bh
))
2124 goto zap_buffer_unlocked
;
2126 /* OK, we have data buffer in journaled mode */
2127 write_lock(&journal
->j_state_lock
);
2128 jbd_lock_bh_state(bh
);
2129 spin_lock(&journal
->j_list_lock
);
2131 jh
= jbd2_journal_grab_journal_head(bh
);
2133 goto zap_buffer_no_jh
;
2136 * We cannot remove the buffer from checkpoint lists until the
2137 * transaction adding inode to orphan list (let's call it T)
2138 * is committed. Otherwise if the transaction changing the
2139 * buffer would be cleaned from the journal before T is
2140 * committed, a crash will cause that the correct contents of
2141 * the buffer will be lost. On the other hand we have to
2142 * clear the buffer dirty bit at latest at the moment when the
2143 * transaction marking the buffer as freed in the filesystem
2144 * structures is committed because from that moment on the
2145 * block can be reallocated and used by a different page.
2146 * Since the block hasn't been freed yet but the inode has
2147 * already been added to orphan list, it is safe for us to add
2148 * the buffer to BJ_Forget list of the newest transaction.
2150 * Also we have to clear buffer_mapped flag of a truncated buffer
2151 * because the buffer_head may be attached to the page straddling
2152 * i_size (can happen only when blocksize < pagesize) and thus the
2153 * buffer_head can be reused when the file is extended again. So we end
2154 * up keeping around invalidated buffers attached to transactions'
2155 * BJ_Forget list just to stop checkpointing code from cleaning up
2156 * the transaction this buffer was modified in.
2158 transaction
= jh
->b_transaction
;
2159 if (transaction
== NULL
) {
2160 /* First case: not on any transaction. If it
2161 * has no checkpoint link, then we can zap it:
2162 * it's a writeback-mode buffer so we don't care
2163 * if it hits disk safely. */
2164 if (!jh
->b_cp_transaction
) {
2165 JBUFFER_TRACE(jh
, "not on any transaction: zap");
2169 if (!buffer_dirty(bh
)) {
2170 /* bdflush has written it. We can drop it now */
2171 __jbd2_journal_remove_checkpoint(jh
);
2175 /* OK, it must be in the journal but still not
2176 * written fully to disk: it's metadata or
2177 * journaled data... */
2179 if (journal
->j_running_transaction
) {
2180 /* ... and once the current transaction has
2181 * committed, the buffer won't be needed any
2183 JBUFFER_TRACE(jh
, "checkpointed: add to BJ_Forget");
2184 may_free
= __dispose_buffer(jh
,
2185 journal
->j_running_transaction
);
2188 /* There is no currently-running transaction. So the
2189 * orphan record which we wrote for this file must have
2190 * passed into commit. We must attach this buffer to
2191 * the committing transaction, if it exists. */
2192 if (journal
->j_committing_transaction
) {
2193 JBUFFER_TRACE(jh
, "give to committing trans");
2194 may_free
= __dispose_buffer(jh
,
2195 journal
->j_committing_transaction
);
2198 /* The orphan record's transaction has
2199 * committed. We can cleanse this buffer */
2200 clear_buffer_jbddirty(bh
);
2201 __jbd2_journal_remove_checkpoint(jh
);
2205 } else if (transaction
== journal
->j_committing_transaction
) {
2206 JBUFFER_TRACE(jh
, "on committing transaction");
2208 * The buffer is committing, we simply cannot touch
2209 * it. If the page is straddling i_size we have to wait
2210 * for commit and try again.
2213 jbd2_journal_put_journal_head(jh
);
2214 spin_unlock(&journal
->j_list_lock
);
2215 jbd_unlock_bh_state(bh
);
2216 write_unlock(&journal
->j_state_lock
);
2220 * OK, buffer won't be reachable after truncate. We just set
2221 * j_next_transaction to the running transaction (if there is
2222 * one) and mark buffer as freed so that commit code knows it
2223 * should clear dirty bits when it is done with the buffer.
2225 set_buffer_freed(bh
);
2226 if (journal
->j_running_transaction
&& buffer_jbddirty(bh
))
2227 jh
->b_next_transaction
= journal
->j_running_transaction
;
2228 jbd2_journal_put_journal_head(jh
);
2229 spin_unlock(&journal
->j_list_lock
);
2230 jbd_unlock_bh_state(bh
);
2231 write_unlock(&journal
->j_state_lock
);
2234 /* Good, the buffer belongs to the running transaction.
2235 * We are writing our own transaction's data, not any
2236 * previous one's, so it is safe to throw it away
2237 * (remember that we expect the filesystem to have set
2238 * i_size already for this truncate so recovery will not
2239 * expose the disk blocks we are discarding here.) */
2240 J_ASSERT_JH(jh
, transaction
== journal
->j_running_transaction
);
2241 JBUFFER_TRACE(jh
, "on running transaction");
2242 may_free
= __dispose_buffer(jh
, transaction
);
2247 * This is tricky. Although the buffer is truncated, it may be reused
2248 * if blocksize < pagesize and it is attached to the page straddling
2249 * EOF. Since the buffer might have been added to BJ_Forget list of the
2250 * running transaction, journal_get_write_access() won't clear
2251 * b_modified and credit accounting gets confused. So clear b_modified
2255 jbd2_journal_put_journal_head(jh
);
2257 spin_unlock(&journal
->j_list_lock
);
2258 jbd_unlock_bh_state(bh
);
2259 write_unlock(&journal
->j_state_lock
);
2260 zap_buffer_unlocked
:
2261 clear_buffer_dirty(bh
);
2262 J_ASSERT_BH(bh
, !buffer_jbddirty(bh
));
2263 clear_buffer_mapped(bh
);
2264 clear_buffer_req(bh
);
2265 clear_buffer_new(bh
);
2266 clear_buffer_delay(bh
);
2267 clear_buffer_unwritten(bh
);
2273 * void jbd2_journal_invalidatepage()
2274 * @journal: journal to use for flush...
2275 * @page: page to flush
2276 * @offset: start of the range to invalidate
2277 * @length: length of the range to invalidate
2279 * Reap page buffers containing data after in the specified range in page.
2280 * Can return -EBUSY if buffers are part of the committing transaction and
2281 * the page is straddling i_size. Caller then has to wait for current commit
2284 int jbd2_journal_invalidatepage(journal_t
*journal
,
2286 unsigned int offset
,
2287 unsigned int length
)
2289 struct buffer_head
*head
, *bh
, *next
;
2290 unsigned int stop
= offset
+ length
;
2291 unsigned int curr_off
= 0;
2292 int partial_page
= (offset
|| length
< PAGE_SIZE
);
2296 if (!PageLocked(page
))
2298 if (!page_has_buffers(page
))
2301 BUG_ON(stop
> PAGE_SIZE
|| stop
< length
);
2303 /* We will potentially be playing with lists other than just the
2304 * data lists (especially for journaled data mode), so be
2305 * cautious in our locking. */
2307 head
= bh
= page_buffers(page
);
2309 unsigned int next_off
= curr_off
+ bh
->b_size
;
2310 next
= bh
->b_this_page
;
2312 if (next_off
> stop
)
2315 if (offset
<= curr_off
) {
2316 /* This block is wholly outside the truncation point */
2318 ret
= journal_unmap_buffer(journal
, bh
, partial_page
);
2324 curr_off
= next_off
;
2327 } while (bh
!= head
);
2329 if (!partial_page
) {
2330 if (may_free
&& try_to_free_buffers(page
))
2331 J_ASSERT(!page_has_buffers(page
));
2337 * File a buffer on the given transaction list.
2339 void __jbd2_journal_file_buffer(struct journal_head
*jh
,
2340 transaction_t
*transaction
, int jlist
)
2342 struct journal_head
**list
= NULL
;
2344 struct buffer_head
*bh
= jh2bh(jh
);
2346 J_ASSERT_JH(jh
, jbd_is_locked_bh_state(bh
));
2347 assert_spin_locked(&transaction
->t_journal
->j_list_lock
);
2349 J_ASSERT_JH(jh
, jh
->b_jlist
< BJ_Types
);
2350 J_ASSERT_JH(jh
, jh
->b_transaction
== transaction
||
2351 jh
->b_transaction
== NULL
);
2353 if (jh
->b_transaction
&& jh
->b_jlist
== jlist
)
2356 if (jlist
== BJ_Metadata
|| jlist
== BJ_Reserved
||
2357 jlist
== BJ_Shadow
|| jlist
== BJ_Forget
) {
2359 * For metadata buffers, we track dirty bit in buffer_jbddirty
2360 * instead of buffer_dirty. We should not see a dirty bit set
2361 * here because we clear it in do_get_write_access but e.g.
2362 * tune2fs can modify the sb and set the dirty bit at any time
2363 * so we try to gracefully handle that.
2365 if (buffer_dirty(bh
))
2366 warn_dirty_buffer(bh
);
2367 if (test_clear_buffer_dirty(bh
) ||
2368 test_clear_buffer_jbddirty(bh
))
2372 if (jh
->b_transaction
)
2373 __jbd2_journal_temp_unlink_buffer(jh
);
2375 jbd2_journal_grab_journal_head(bh
);
2376 jh
->b_transaction
= transaction
;
2380 J_ASSERT_JH(jh
, !jh
->b_committed_data
);
2381 J_ASSERT_JH(jh
, !jh
->b_frozen_data
);
2384 transaction
->t_nr_buffers
++;
2385 list
= &transaction
->t_buffers
;
2388 list
= &transaction
->t_forget
;
2391 list
= &transaction
->t_shadow_list
;
2394 list
= &transaction
->t_reserved_list
;
2398 __blist_add_buffer(list
, jh
);
2399 jh
->b_jlist
= jlist
;
2402 set_buffer_jbddirty(bh
);
2405 void jbd2_journal_file_buffer(struct journal_head
*jh
,
2406 transaction_t
*transaction
, int jlist
)
2408 jbd_lock_bh_state(jh2bh(jh
));
2409 spin_lock(&transaction
->t_journal
->j_list_lock
);
2410 __jbd2_journal_file_buffer(jh
, transaction
, jlist
);
2411 spin_unlock(&transaction
->t_journal
->j_list_lock
);
2412 jbd_unlock_bh_state(jh2bh(jh
));
2416 * Remove a buffer from its current buffer list in preparation for
2417 * dropping it from its current transaction entirely. If the buffer has
2418 * already started to be used by a subsequent transaction, refile the
2419 * buffer on that transaction's metadata list.
2421 * Called under j_list_lock
2422 * Called under jbd_lock_bh_state(jh2bh(jh))
2424 * jh and bh may be already free when this function returns
2426 void __jbd2_journal_refile_buffer(struct journal_head
*jh
)
2428 int was_dirty
, jlist
;
2429 struct buffer_head
*bh
= jh2bh(jh
);
2431 J_ASSERT_JH(jh
, jbd_is_locked_bh_state(bh
));
2432 if (jh
->b_transaction
)
2433 assert_spin_locked(&jh
->b_transaction
->t_journal
->j_list_lock
);
2435 /* If the buffer is now unused, just drop it. */
2436 if (jh
->b_next_transaction
== NULL
) {
2437 __jbd2_journal_unfile_buffer(jh
);
2442 * It has been modified by a later transaction: add it to the new
2443 * transaction's metadata list.
2446 was_dirty
= test_clear_buffer_jbddirty(bh
);
2447 __jbd2_journal_temp_unlink_buffer(jh
);
2449 * We set b_transaction here because b_next_transaction will inherit
2450 * our jh reference and thus __jbd2_journal_file_buffer() must not
2453 jh
->b_transaction
= jh
->b_next_transaction
;
2454 jh
->b_next_transaction
= NULL
;
2455 if (buffer_freed(bh
))
2457 else if (jh
->b_modified
)
2458 jlist
= BJ_Metadata
;
2460 jlist
= BJ_Reserved
;
2461 __jbd2_journal_file_buffer(jh
, jh
->b_transaction
, jlist
);
2462 J_ASSERT_JH(jh
, jh
->b_transaction
->t_state
== T_RUNNING
);
2465 set_buffer_jbddirty(bh
);
2469 * __jbd2_journal_refile_buffer() with necessary locking added. We take our
2470 * bh reference so that we can safely unlock bh.
2472 * The jh and bh may be freed by this call.
2474 void jbd2_journal_refile_buffer(journal_t
*journal
, struct journal_head
*jh
)
2476 struct buffer_head
*bh
= jh2bh(jh
);
2478 /* Get reference so that buffer cannot be freed before we unlock it */
2480 jbd_lock_bh_state(bh
);
2481 spin_lock(&journal
->j_list_lock
);
2482 __jbd2_journal_refile_buffer(jh
);
2483 jbd_unlock_bh_state(bh
);
2484 spin_unlock(&journal
->j_list_lock
);
2489 * File inode in the inode list of the handle's transaction
2491 static int jbd2_journal_file_inode(handle_t
*handle
, struct jbd2_inode
*jinode
,
2492 unsigned long flags
)
2494 transaction_t
*transaction
= handle
->h_transaction
;
2497 if (is_handle_aborted(handle
))
2499 journal
= transaction
->t_journal
;
2501 jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode
->i_vfs_inode
->i_ino
,
2502 transaction
->t_tid
);
2505 * First check whether inode isn't already on the transaction's
2506 * lists without taking the lock. Note that this check is safe
2507 * without the lock as we cannot race with somebody removing inode
2508 * from the transaction. The reason is that we remove inode from the
2509 * transaction only in journal_release_jbd_inode() and when we commit
2510 * the transaction. We are guarded from the first case by holding
2511 * a reference to the inode. We are safe against the second case
2512 * because if jinode->i_transaction == transaction, commit code
2513 * cannot touch the transaction because we hold reference to it,
2514 * and if jinode->i_next_transaction == transaction, commit code
2515 * will only file the inode where we want it.
2517 if ((jinode
->i_transaction
== transaction
||
2518 jinode
->i_next_transaction
== transaction
) &&
2519 (jinode
->i_flags
& flags
) == flags
)
2522 spin_lock(&journal
->j_list_lock
);
2523 jinode
->i_flags
|= flags
;
2524 /* Is inode already attached where we need it? */
2525 if (jinode
->i_transaction
== transaction
||
2526 jinode
->i_next_transaction
== transaction
)
2530 * We only ever set this variable to 1 so the test is safe. Since
2531 * t_need_data_flush is likely to be set, we do the test to save some
2532 * cacheline bouncing
2534 if (!transaction
->t_need_data_flush
)
2535 transaction
->t_need_data_flush
= 1;
2536 /* On some different transaction's list - should be
2537 * the committing one */
2538 if (jinode
->i_transaction
) {
2539 J_ASSERT(jinode
->i_next_transaction
== NULL
);
2540 J_ASSERT(jinode
->i_transaction
==
2541 journal
->j_committing_transaction
);
2542 jinode
->i_next_transaction
= transaction
;
2545 /* Not on any transaction list... */
2546 J_ASSERT(!jinode
->i_next_transaction
);
2547 jinode
->i_transaction
= transaction
;
2548 list_add(&jinode
->i_list
, &transaction
->t_inode_list
);
2550 spin_unlock(&journal
->j_list_lock
);
2555 int jbd2_journal_inode_add_write(handle_t
*handle
, struct jbd2_inode
*jinode
)
2557 return jbd2_journal_file_inode(handle
, jinode
,
2558 JI_WRITE_DATA
| JI_WAIT_DATA
);
2561 int jbd2_journal_inode_add_wait(handle_t
*handle
, struct jbd2_inode
*jinode
)
2563 return jbd2_journal_file_inode(handle
, jinode
, JI_WAIT_DATA
);
2567 * File truncate and transaction commit interact with each other in a
2568 * non-trivial way. If a transaction writing data block A is
2569 * committing, we cannot discard the data by truncate until we have
2570 * written them. Otherwise if we crashed after the transaction with
2571 * write has committed but before the transaction with truncate has
2572 * committed, we could see stale data in block A. This function is a
2573 * helper to solve this problem. It starts writeout of the truncated
2574 * part in case it is in the committing transaction.
2576 * Filesystem code must call this function when inode is journaled in
2577 * ordered mode before truncation happens and after the inode has been
2578 * placed on orphan list with the new inode size. The second condition
2579 * avoids the race that someone writes new data and we start
2580 * committing the transaction after this function has been called but
2581 * before a transaction for truncate is started (and furthermore it
2582 * allows us to optimize the case where the addition to orphan list
2583 * happens in the same transaction as write --- we don't have to write
2584 * any data in such case).
2586 int jbd2_journal_begin_ordered_truncate(journal_t
*journal
,
2587 struct jbd2_inode
*jinode
,
2590 transaction_t
*inode_trans
, *commit_trans
;
2593 /* This is a quick check to avoid locking if not necessary */
2594 if (!jinode
->i_transaction
)
2596 /* Locks are here just to force reading of recent values, it is
2597 * enough that the transaction was not committing before we started
2598 * a transaction adding the inode to orphan list */
2599 read_lock(&journal
->j_state_lock
);
2600 commit_trans
= journal
->j_committing_transaction
;
2601 read_unlock(&journal
->j_state_lock
);
2602 spin_lock(&journal
->j_list_lock
);
2603 inode_trans
= jinode
->i_transaction
;
2604 spin_unlock(&journal
->j_list_lock
);
2605 if (inode_trans
== commit_trans
) {
2606 ret
= filemap_fdatawrite_range(jinode
->i_vfs_inode
->i_mapping
,
2607 new_size
, LLONG_MAX
);
2609 jbd2_journal_abort(journal
, ret
);