1 // SPDX-License-Identifier: GPL-2.0+
3 * linux/fs/jbd2/transaction.c
5 * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
7 * Copyright 1998 Red Hat corp --- All Rights Reserved
9 * Generic filesystem transaction handling code; part of the ext2fs
12 * This file manages transactions (compound commits managed by the
13 * journaling code) and handles (individual atomic operations by the
17 #include <linux/time.h>
19 #include <linux/jbd2.h>
20 #include <linux/errno.h>
21 #include <linux/slab.h>
22 #include <linux/timer.h>
24 #include <linux/highmem.h>
25 #include <linux/hrtimer.h>
26 #include <linux/backing-dev.h>
27 #include <linux/bug.h>
28 #include <linux/module.h>
29 #include <linux/sched/mm.h>
31 #include <trace/events/jbd2.h>
33 static void __jbd2_journal_temp_unlink_buffer(struct journal_head
*jh
);
34 static void __jbd2_journal_unfile_buffer(struct journal_head
*jh
);
36 static struct kmem_cache
*transaction_cache
;
37 int __init
jbd2_journal_init_transaction_cache(void)
39 J_ASSERT(!transaction_cache
);
40 transaction_cache
= kmem_cache_create("jbd2_transaction_s",
41 sizeof(transaction_t
),
43 SLAB_HWCACHE_ALIGN
|SLAB_TEMPORARY
,
45 if (transaction_cache
)
50 void jbd2_journal_destroy_transaction_cache(void)
52 kmem_cache_destroy(transaction_cache
);
53 transaction_cache
= NULL
;
56 void jbd2_journal_free_transaction(transaction_t
*transaction
)
58 if (unlikely(ZERO_OR_NULL_PTR(transaction
)))
60 kmem_cache_free(transaction_cache
, transaction
);
64 * jbd2_get_transaction: obtain a new transaction_t object.
66 * Simply initialise a new transaction. Initialize it in
67 * RUNNING state and add it to the current journal (which should not
68 * have an existing running transaction: we only make a new transaction
69 * once we have started to commit the old one).
72 * The journal MUST be locked. We don't perform atomic mallocs on the
73 * new transaction and we can't block without protecting against other
74 * processes trying to touch the journal while it is in transition.
78 static void jbd2_get_transaction(journal_t
*journal
,
79 transaction_t
*transaction
)
81 transaction
->t_journal
= journal
;
82 transaction
->t_state
= T_RUNNING
;
83 transaction
->t_start_time
= ktime_get();
84 transaction
->t_tid
= journal
->j_transaction_sequence
++;
85 transaction
->t_expires
= jiffies
+ journal
->j_commit_interval
;
86 spin_lock_init(&transaction
->t_handle_lock
);
87 atomic_set(&transaction
->t_updates
, 0);
88 atomic_set(&transaction
->t_outstanding_credits
,
89 atomic_read(&journal
->j_reserved_credits
));
90 atomic_set(&transaction
->t_handle_count
, 0);
91 INIT_LIST_HEAD(&transaction
->t_inode_list
);
92 INIT_LIST_HEAD(&transaction
->t_private_list
);
94 /* Set up the commit timer for the new transaction. */
95 journal
->j_commit_timer
.expires
= round_jiffies_up(transaction
->t_expires
);
96 add_timer(&journal
->j_commit_timer
);
98 J_ASSERT(journal
->j_running_transaction
== NULL
);
99 journal
->j_running_transaction
= transaction
;
100 transaction
->t_max_wait
= 0;
101 transaction
->t_start
= jiffies
;
102 transaction
->t_requested
= 0;
108 * A handle_t is an object which represents a single atomic update to a
109 * filesystem, and which tracks all of the modifications which form part
110 * of that one update.
114 * Update transaction's maximum wait time, if debugging is enabled.
116 * In order for t_max_wait to be reliable, it must be protected by a
117 * lock. But doing so will mean that start_this_handle() can not be
118 * run in parallel on SMP systems, which limits our scalability. So
119 * unless debugging is enabled, we no longer update t_max_wait, which
120 * means that maximum wait time reported by the jbd2_run_stats
121 * tracepoint will always be zero.
123 static inline void update_t_max_wait(transaction_t
*transaction
,
126 #ifdef CONFIG_JBD2_DEBUG
127 if (jbd2_journal_enable_debug
&&
128 time_after(transaction
->t_start
, ts
)) {
129 ts
= jbd2_time_diff(ts
, transaction
->t_start
);
130 spin_lock(&transaction
->t_handle_lock
);
131 if (ts
> transaction
->t_max_wait
)
132 transaction
->t_max_wait
= ts
;
133 spin_unlock(&transaction
->t_handle_lock
);
139 * Wait until running transaction passes to T_FLUSH state and new transaction
140 * can thus be started. Also starts the commit if needed. The function expects
141 * running transaction to exist and releases j_state_lock.
143 static void wait_transaction_locked(journal_t
*journal
)
144 __releases(journal
->j_state_lock
)
148 tid_t tid
= journal
->j_running_transaction
->t_tid
;
150 prepare_to_wait(&journal
->j_wait_transaction_locked
, &wait
,
151 TASK_UNINTERRUPTIBLE
);
152 need_to_start
= !tid_geq(journal
->j_commit_request
, tid
);
153 read_unlock(&journal
->j_state_lock
);
155 jbd2_log_start_commit(journal
, tid
);
156 jbd2_might_wait_for_commit(journal
);
158 finish_wait(&journal
->j_wait_transaction_locked
, &wait
);
162 * Wait until running transaction transitions from T_SWITCH to T_FLUSH
163 * state and new transaction can thus be started. The function releases
166 static void wait_transaction_switching(journal_t
*journal
)
167 __releases(journal
->j_state_lock
)
171 if (WARN_ON(!journal
->j_running_transaction
||
172 journal
->j_running_transaction
->t_state
!= T_SWITCH
))
174 prepare_to_wait(&journal
->j_wait_transaction_locked
, &wait
,
175 TASK_UNINTERRUPTIBLE
);
176 read_unlock(&journal
->j_state_lock
);
178 * We don't call jbd2_might_wait_for_commit() here as there's no
179 * waiting for outstanding handles happening anymore in T_SWITCH state
180 * and handling of reserved handles actually relies on that for
184 finish_wait(&journal
->j_wait_transaction_locked
, &wait
);
187 static void sub_reserved_credits(journal_t
*journal
, int blocks
)
189 atomic_sub(blocks
, &journal
->j_reserved_credits
);
190 wake_up(&journal
->j_wait_reserved
);
194 * Wait until we can add credits for handle to the running transaction. Called
195 * with j_state_lock held for reading. Returns 0 if handle joined the running
196 * transaction. Returns 1 if we had to wait, j_state_lock is dropped, and
199 static int add_transaction_credits(journal_t
*journal
, int blocks
,
202 transaction_t
*t
= journal
->j_running_transaction
;
204 int total
= blocks
+ rsv_blocks
;
207 * If the current transaction is locked down for commit, wait
208 * for the lock to be released.
210 if (t
->t_state
!= T_RUNNING
) {
211 WARN_ON_ONCE(t
->t_state
>= T_FLUSH
);
212 wait_transaction_locked(journal
);
217 * If there is not enough space left in the log to write all
218 * potential buffers requested by this operation, we need to
219 * stall pending a log checkpoint to free some more log space.
221 needed
= atomic_add_return(total
, &t
->t_outstanding_credits
);
222 if (needed
> journal
->j_max_transaction_buffers
) {
224 * If the current transaction is already too large,
225 * then start to commit it: we can then go back and
226 * attach this handle to a new transaction.
228 atomic_sub(total
, &t
->t_outstanding_credits
);
231 * Is the number of reserved credits in the current transaction too
232 * big to fit this handle? Wait until reserved credits are freed.
234 if (atomic_read(&journal
->j_reserved_credits
) + total
>
235 journal
->j_max_transaction_buffers
) {
236 read_unlock(&journal
->j_state_lock
);
237 jbd2_might_wait_for_commit(journal
);
238 wait_event(journal
->j_wait_reserved
,
239 atomic_read(&journal
->j_reserved_credits
) + total
<=
240 journal
->j_max_transaction_buffers
);
244 wait_transaction_locked(journal
);
249 * The commit code assumes that it can get enough log space
250 * without forcing a checkpoint. This is *critical* for
251 * correctness: a checkpoint of a buffer which is also
252 * associated with a committing transaction creates a deadlock,
253 * so commit simply cannot force through checkpoints.
255 * We must therefore ensure the necessary space in the journal
256 * *before* starting to dirty potentially checkpointed buffers
257 * in the new transaction.
259 if (jbd2_log_space_left(journal
) < jbd2_space_needed(journal
)) {
260 atomic_sub(total
, &t
->t_outstanding_credits
);
261 read_unlock(&journal
->j_state_lock
);
262 jbd2_might_wait_for_commit(journal
);
263 write_lock(&journal
->j_state_lock
);
264 if (jbd2_log_space_left(journal
) < jbd2_space_needed(journal
))
265 __jbd2_log_wait_for_space(journal
);
266 write_unlock(&journal
->j_state_lock
);
270 /* No reservation? We are done... */
274 needed
= atomic_add_return(rsv_blocks
, &journal
->j_reserved_credits
);
275 /* We allow at most half of a transaction to be reserved */
276 if (needed
> journal
->j_max_transaction_buffers
/ 2) {
277 sub_reserved_credits(journal
, rsv_blocks
);
278 atomic_sub(total
, &t
->t_outstanding_credits
);
279 read_unlock(&journal
->j_state_lock
);
280 jbd2_might_wait_for_commit(journal
);
281 wait_event(journal
->j_wait_reserved
,
282 atomic_read(&journal
->j_reserved_credits
) + rsv_blocks
283 <= journal
->j_max_transaction_buffers
/ 2);
290 * start_this_handle: Given a handle, deal with any locking or stalling
291 * needed to make sure that there is enough journal space for the handle
292 * to begin. Attach the handle to a transaction and set up the
293 * transaction's buffer credits.
296 static int start_this_handle(journal_t
*journal
, handle_t
*handle
,
299 transaction_t
*transaction
, *new_transaction
= NULL
;
300 int blocks
= handle
->h_buffer_credits
;
302 unsigned long ts
= jiffies
;
304 if (handle
->h_rsv_handle
)
305 rsv_blocks
= handle
->h_rsv_handle
->h_buffer_credits
;
308 * Limit the number of reserved credits to 1/2 of maximum transaction
309 * size and limit the number of total credits to not exceed maximum
310 * transaction size per operation.
312 if ((rsv_blocks
> journal
->j_max_transaction_buffers
/ 2) ||
313 (rsv_blocks
+ blocks
> journal
->j_max_transaction_buffers
)) {
314 printk(KERN_ERR
"JBD2: %s wants too many credits "
315 "credits:%d rsv_credits:%d max:%d\n",
316 current
->comm
, blocks
, rsv_blocks
,
317 journal
->j_max_transaction_buffers
);
323 if (!journal
->j_running_transaction
) {
325 * If __GFP_FS is not present, then we may be being called from
326 * inside the fs writeback layer, so we MUST NOT fail.
328 if ((gfp_mask
& __GFP_FS
) == 0)
329 gfp_mask
|= __GFP_NOFAIL
;
330 new_transaction
= kmem_cache_zalloc(transaction_cache
,
332 if (!new_transaction
)
336 jbd_debug(3, "New handle %p going live.\n", handle
);
339 * We need to hold j_state_lock until t_updates has been incremented,
340 * for proper journal barrier handling
343 read_lock(&journal
->j_state_lock
);
344 BUG_ON(journal
->j_flags
& JBD2_UNMOUNT
);
345 if (is_journal_aborted(journal
) ||
346 (journal
->j_errno
!= 0 && !(journal
->j_flags
& JBD2_ACK_ERR
))) {
347 read_unlock(&journal
->j_state_lock
);
348 jbd2_journal_free_transaction(new_transaction
);
353 * Wait on the journal's transaction barrier if necessary. Specifically
354 * we allow reserved handles to proceed because otherwise commit could
355 * deadlock on page writeback not being able to complete.
357 if (!handle
->h_reserved
&& journal
->j_barrier_count
) {
358 read_unlock(&journal
->j_state_lock
);
359 wait_event(journal
->j_wait_transaction_locked
,
360 journal
->j_barrier_count
== 0);
364 if (!journal
->j_running_transaction
) {
365 read_unlock(&journal
->j_state_lock
);
366 if (!new_transaction
)
367 goto alloc_transaction
;
368 write_lock(&journal
->j_state_lock
);
369 if (!journal
->j_running_transaction
&&
370 (handle
->h_reserved
|| !journal
->j_barrier_count
)) {
371 jbd2_get_transaction(journal
, new_transaction
);
372 new_transaction
= NULL
;
374 write_unlock(&journal
->j_state_lock
);
378 transaction
= journal
->j_running_transaction
;
380 if (!handle
->h_reserved
) {
381 /* We may have dropped j_state_lock - restart in that case */
382 if (add_transaction_credits(journal
, blocks
, rsv_blocks
))
386 * We have handle reserved so we are allowed to join T_LOCKED
387 * transaction and we don't have to check for transaction size
388 * and journal space. But we still have to wait while running
389 * transaction is being switched to a committing one as it
390 * won't wait for any handles anymore.
392 if (transaction
->t_state
== T_SWITCH
) {
393 wait_transaction_switching(journal
);
396 sub_reserved_credits(journal
, blocks
);
397 handle
->h_reserved
= 0;
400 /* OK, account for the buffers that this operation expects to
401 * use and add the handle to the running transaction.
403 update_t_max_wait(transaction
, ts
);
404 handle
->h_transaction
= transaction
;
405 handle
->h_requested_credits
= blocks
;
406 handle
->h_start_jiffies
= jiffies
;
407 atomic_inc(&transaction
->t_updates
);
408 atomic_inc(&transaction
->t_handle_count
);
409 jbd_debug(4, "Handle %p given %d credits (total %d, free %lu)\n",
411 atomic_read(&transaction
->t_outstanding_credits
),
412 jbd2_log_space_left(journal
));
413 read_unlock(&journal
->j_state_lock
);
414 current
->journal_info
= handle
;
416 rwsem_acquire_read(&journal
->j_trans_commit_map
, 0, 0, _THIS_IP_
);
417 jbd2_journal_free_transaction(new_transaction
);
419 * Ensure that no allocations done while the transaction is open are
420 * going to recurse back to the fs layer.
422 handle
->saved_alloc_context
= memalloc_nofs_save();
426 /* Allocate a new handle. This should probably be in a slab... */
427 static handle_t
*new_handle(int nblocks
)
429 handle_t
*handle
= jbd2_alloc_handle(GFP_NOFS
);
432 handle
->h_buffer_credits
= nblocks
;
438 handle_t
*jbd2__journal_start(journal_t
*journal
, int nblocks
, int rsv_blocks
,
439 gfp_t gfp_mask
, unsigned int type
,
440 unsigned int line_no
)
442 handle_t
*handle
= journal_current_handle();
446 return ERR_PTR(-EROFS
);
449 J_ASSERT(handle
->h_transaction
->t_journal
== journal
);
454 handle
= new_handle(nblocks
);
456 return ERR_PTR(-ENOMEM
);
458 handle_t
*rsv_handle
;
460 rsv_handle
= new_handle(rsv_blocks
);
462 jbd2_free_handle(handle
);
463 return ERR_PTR(-ENOMEM
);
465 rsv_handle
->h_reserved
= 1;
466 rsv_handle
->h_journal
= journal
;
467 handle
->h_rsv_handle
= rsv_handle
;
470 err
= start_this_handle(journal
, handle
, gfp_mask
);
472 if (handle
->h_rsv_handle
)
473 jbd2_free_handle(handle
->h_rsv_handle
);
474 jbd2_free_handle(handle
);
477 handle
->h_type
= type
;
478 handle
->h_line_no
= line_no
;
479 trace_jbd2_handle_start(journal
->j_fs_dev
->bd_dev
,
480 handle
->h_transaction
->t_tid
, type
,
485 EXPORT_SYMBOL(jbd2__journal_start
);
489 * handle_t *jbd2_journal_start() - Obtain a new handle.
490 * @journal: Journal to start transaction on.
491 * @nblocks: number of block buffer we might modify
493 * We make sure that the transaction can guarantee at least nblocks of
494 * modified buffers in the log. We block until the log can guarantee
495 * that much space. Additionally, if rsv_blocks > 0, we also create another
496 * handle with rsv_blocks reserved blocks in the journal. This handle is
497 * is stored in h_rsv_handle. It is not attached to any particular transaction
498 * and thus doesn't block transaction commit. If the caller uses this reserved
499 * handle, it has to set h_rsv_handle to NULL as otherwise jbd2_journal_stop()
500 * on the parent handle will dispose the reserved one. Reserved handle has to
501 * be converted to a normal handle using jbd2_journal_start_reserved() before
504 * Return a pointer to a newly allocated handle, or an ERR_PTR() value
507 handle_t
*jbd2_journal_start(journal_t
*journal
, int nblocks
)
509 return jbd2__journal_start(journal
, nblocks
, 0, GFP_NOFS
, 0, 0);
511 EXPORT_SYMBOL(jbd2_journal_start
);
513 void jbd2_journal_free_reserved(handle_t
*handle
)
515 journal_t
*journal
= handle
->h_journal
;
517 WARN_ON(!handle
->h_reserved
);
518 sub_reserved_credits(journal
, handle
->h_buffer_credits
);
519 jbd2_free_handle(handle
);
521 EXPORT_SYMBOL(jbd2_journal_free_reserved
);
524 * int jbd2_journal_start_reserved() - start reserved handle
525 * @handle: handle to start
526 * @type: for handle statistics
527 * @line_no: for handle statistics
529 * Start handle that has been previously reserved with jbd2_journal_reserve().
530 * This attaches @handle to the running transaction (or creates one if there's
531 * not transaction running). Unlike jbd2_journal_start() this function cannot
532 * block on journal commit, checkpointing, or similar stuff. It can block on
533 * memory allocation or frozen journal though.
535 * Return 0 on success, non-zero on error - handle is freed in that case.
537 int jbd2_journal_start_reserved(handle_t
*handle
, unsigned int type
,
538 unsigned int line_no
)
540 journal_t
*journal
= handle
->h_journal
;
543 if (WARN_ON(!handle
->h_reserved
)) {
544 /* Someone passed in normal handle? Just stop it. */
545 jbd2_journal_stop(handle
);
549 * Usefulness of mixing of reserved and unreserved handles is
550 * questionable. So far nobody seems to need it so just error out.
552 if (WARN_ON(current
->journal_info
)) {
553 jbd2_journal_free_reserved(handle
);
557 handle
->h_journal
= NULL
;
559 * GFP_NOFS is here because callers are likely from writeback or
560 * similarly constrained call sites
562 ret
= start_this_handle(journal
, handle
, GFP_NOFS
);
564 handle
->h_journal
= journal
;
565 jbd2_journal_free_reserved(handle
);
568 handle
->h_type
= type
;
569 handle
->h_line_no
= line_no
;
572 EXPORT_SYMBOL(jbd2_journal_start_reserved
);
575 * int jbd2_journal_extend() - extend buffer credits.
576 * @handle: handle to 'extend'
577 * @nblocks: nr blocks to try to extend by.
579 * Some transactions, such as large extends and truncates, can be done
580 * atomically all at once or in several stages. The operation requests
581 * a credit for a number of buffer modifications in advance, but can
582 * extend its credit if it needs more.
584 * jbd2_journal_extend tries to give the running handle more buffer credits.
585 * It does not guarantee that allocation - this is a best-effort only.
586 * The calling process MUST be able to deal cleanly with a failure to
589 * Return 0 on success, non-zero on failure.
591 * return code < 0 implies an error
592 * return code > 0 implies normal transaction-full status.
594 int jbd2_journal_extend(handle_t
*handle
, int nblocks
)
596 transaction_t
*transaction
= handle
->h_transaction
;
601 if (is_handle_aborted(handle
))
603 journal
= transaction
->t_journal
;
607 read_lock(&journal
->j_state_lock
);
609 /* Don't extend a locked-down transaction! */
610 if (transaction
->t_state
!= T_RUNNING
) {
611 jbd_debug(3, "denied handle %p %d blocks: "
612 "transaction not running\n", handle
, nblocks
);
616 spin_lock(&transaction
->t_handle_lock
);
617 wanted
= atomic_add_return(nblocks
,
618 &transaction
->t_outstanding_credits
);
620 if (wanted
> journal
->j_max_transaction_buffers
) {
621 jbd_debug(3, "denied handle %p %d blocks: "
622 "transaction too large\n", handle
, nblocks
);
623 atomic_sub(nblocks
, &transaction
->t_outstanding_credits
);
627 if (wanted
+ (wanted
>> JBD2_CONTROL_BLOCKS_SHIFT
) >
628 jbd2_log_space_left(journal
)) {
629 jbd_debug(3, "denied handle %p %d blocks: "
630 "insufficient log space\n", handle
, nblocks
);
631 atomic_sub(nblocks
, &transaction
->t_outstanding_credits
);
635 trace_jbd2_handle_extend(journal
->j_fs_dev
->bd_dev
,
637 handle
->h_type
, handle
->h_line_no
,
638 handle
->h_buffer_credits
,
641 handle
->h_buffer_credits
+= nblocks
;
642 handle
->h_requested_credits
+= nblocks
;
645 jbd_debug(3, "extended handle %p by %d\n", handle
, nblocks
);
647 spin_unlock(&transaction
->t_handle_lock
);
649 read_unlock(&journal
->j_state_lock
);
655 * int jbd2_journal_restart() - restart a handle .
656 * @handle: handle to restart
657 * @nblocks: nr credits requested
658 * @gfp_mask: memory allocation flags (for start_this_handle)
660 * Restart a handle for a multi-transaction filesystem
663 * If the jbd2_journal_extend() call above fails to grant new buffer credits
664 * to a running handle, a call to jbd2_journal_restart will commit the
665 * handle's transaction so far and reattach the handle to a new
666 * transaction capable of guaranteeing the requested number of
667 * credits. We preserve reserved handle if there's any attached to the
670 int jbd2__journal_restart(handle_t
*handle
, int nblocks
, gfp_t gfp_mask
)
672 transaction_t
*transaction
= handle
->h_transaction
;
675 int need_to_start
, ret
;
677 /* If we've had an abort of any type, don't even think about
678 * actually doing the restart! */
679 if (is_handle_aborted(handle
))
681 journal
= transaction
->t_journal
;
684 * First unlink the handle from its current transaction, and start the
687 J_ASSERT(atomic_read(&transaction
->t_updates
) > 0);
688 J_ASSERT(journal_current_handle() == handle
);
690 read_lock(&journal
->j_state_lock
);
691 spin_lock(&transaction
->t_handle_lock
);
692 atomic_sub(handle
->h_buffer_credits
,
693 &transaction
->t_outstanding_credits
);
694 if (handle
->h_rsv_handle
) {
695 sub_reserved_credits(journal
,
696 handle
->h_rsv_handle
->h_buffer_credits
);
698 if (atomic_dec_and_test(&transaction
->t_updates
))
699 wake_up(&journal
->j_wait_updates
);
700 tid
= transaction
->t_tid
;
701 spin_unlock(&transaction
->t_handle_lock
);
702 handle
->h_transaction
= NULL
;
703 current
->journal_info
= NULL
;
705 jbd_debug(2, "restarting handle %p\n", handle
);
706 need_to_start
= !tid_geq(journal
->j_commit_request
, tid
);
707 read_unlock(&journal
->j_state_lock
);
709 jbd2_log_start_commit(journal
, tid
);
711 rwsem_release(&journal
->j_trans_commit_map
, 1, _THIS_IP_
);
712 handle
->h_buffer_credits
= nblocks
;
714 * Restore the original nofs context because the journal restart
715 * is basically the same thing as journal stop and start.
716 * start_this_handle will start a new nofs context.
718 memalloc_nofs_restore(handle
->saved_alloc_context
);
719 ret
= start_this_handle(journal
, handle
, gfp_mask
);
722 EXPORT_SYMBOL(jbd2__journal_restart
);
725 int jbd2_journal_restart(handle_t
*handle
, int nblocks
)
727 return jbd2__journal_restart(handle
, nblocks
, GFP_NOFS
);
729 EXPORT_SYMBOL(jbd2_journal_restart
);
732 * void jbd2_journal_lock_updates () - establish a transaction barrier.
733 * @journal: Journal to establish a barrier on.
735 * This locks out any further updates from being started, and blocks
736 * until all existing updates have completed, returning only once the
737 * journal is in a quiescent state with no updates running.
739 * The journal lock should not be held on entry.
741 void jbd2_journal_lock_updates(journal_t
*journal
)
745 jbd2_might_wait_for_commit(journal
);
747 write_lock(&journal
->j_state_lock
);
748 ++journal
->j_barrier_count
;
750 /* Wait until there are no reserved handles */
751 if (atomic_read(&journal
->j_reserved_credits
)) {
752 write_unlock(&journal
->j_state_lock
);
753 wait_event(journal
->j_wait_reserved
,
754 atomic_read(&journal
->j_reserved_credits
) == 0);
755 write_lock(&journal
->j_state_lock
);
758 /* Wait until there are no running updates */
760 transaction_t
*transaction
= journal
->j_running_transaction
;
765 spin_lock(&transaction
->t_handle_lock
);
766 prepare_to_wait(&journal
->j_wait_updates
, &wait
,
767 TASK_UNINTERRUPTIBLE
);
768 if (!atomic_read(&transaction
->t_updates
)) {
769 spin_unlock(&transaction
->t_handle_lock
);
770 finish_wait(&journal
->j_wait_updates
, &wait
);
773 spin_unlock(&transaction
->t_handle_lock
);
774 write_unlock(&journal
->j_state_lock
);
776 finish_wait(&journal
->j_wait_updates
, &wait
);
777 write_lock(&journal
->j_state_lock
);
779 write_unlock(&journal
->j_state_lock
);
782 * We have now established a barrier against other normal updates, but
783 * we also need to barrier against other jbd2_journal_lock_updates() calls
784 * to make sure that we serialise special journal-locked operations
787 mutex_lock(&journal
->j_barrier
);
791 * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier
792 * @journal: Journal to release the barrier on.
794 * Release a transaction barrier obtained with jbd2_journal_lock_updates().
796 * Should be called without the journal lock held.
798 void jbd2_journal_unlock_updates (journal_t
*journal
)
800 J_ASSERT(journal
->j_barrier_count
!= 0);
802 mutex_unlock(&journal
->j_barrier
);
803 write_lock(&journal
->j_state_lock
);
804 --journal
->j_barrier_count
;
805 write_unlock(&journal
->j_state_lock
);
806 wake_up(&journal
->j_wait_transaction_locked
);
809 static void warn_dirty_buffer(struct buffer_head
*bh
)
812 "JBD2: Spotted dirty metadata buffer (dev = %pg, blocknr = %llu). "
813 "There's a risk of filesystem corruption in case of system "
815 bh
->b_bdev
, (unsigned long long)bh
->b_blocknr
);
818 /* Call t_frozen trigger and copy buffer data into jh->b_frozen_data. */
819 static void jbd2_freeze_jh_data(struct journal_head
*jh
)
824 struct buffer_head
*bh
= jh2bh(jh
);
826 J_EXPECT_JH(jh
, buffer_uptodate(bh
), "Possible IO failure.\n");
828 offset
= offset_in_page(bh
->b_data
);
829 source
= kmap_atomic(page
);
830 /* Fire data frozen trigger just before we copy the data */
831 jbd2_buffer_frozen_trigger(jh
, source
+ offset
, jh
->b_triggers
);
832 memcpy(jh
->b_frozen_data
, source
+ offset
, bh
->b_size
);
833 kunmap_atomic(source
);
836 * Now that the frozen data is saved off, we need to store any matching
839 jh
->b_frozen_triggers
= jh
->b_triggers
;
843 * If the buffer is already part of the current transaction, then there
844 * is nothing we need to do. If it is already part of a prior
845 * transaction which we are still committing to disk, then we need to
846 * make sure that we do not overwrite the old copy: we do copy-out to
847 * preserve the copy going to disk. We also account the buffer against
848 * the handle's metadata buffer credits (unless the buffer is already
849 * part of the transaction, that is).
853 do_get_write_access(handle_t
*handle
, struct journal_head
*jh
,
856 struct buffer_head
*bh
;
857 transaction_t
*transaction
= handle
->h_transaction
;
860 char *frozen_buffer
= NULL
;
861 unsigned long start_lock
, time_lock
;
863 if (is_handle_aborted(handle
))
865 journal
= transaction
->t_journal
;
867 jbd_debug(5, "journal_head %p, force_copy %d\n", jh
, force_copy
);
869 JBUFFER_TRACE(jh
, "entry");
873 /* @@@ Need to check for errors here at some point. */
875 start_lock
= jiffies
;
877 jbd_lock_bh_state(bh
);
879 /* If it takes too long to lock the buffer, trace it */
880 time_lock
= jbd2_time_diff(start_lock
, jiffies
);
881 if (time_lock
> HZ
/10)
882 trace_jbd2_lock_buffer_stall(bh
->b_bdev
->bd_dev
,
883 jiffies_to_msecs(time_lock
));
885 /* We now hold the buffer lock so it is safe to query the buffer
886 * state. Is the buffer dirty?
888 * If so, there are two possibilities. The buffer may be
889 * non-journaled, and undergoing a quite legitimate writeback.
890 * Otherwise, it is journaled, and we don't expect dirty buffers
891 * in that state (the buffers should be marked JBD_Dirty
892 * instead.) So either the IO is being done under our own
893 * control and this is a bug, or it's a third party IO such as
894 * dump(8) (which may leave the buffer scheduled for read ---
895 * ie. locked but not dirty) or tune2fs (which may actually have
896 * the buffer dirtied, ugh.) */
898 if (buffer_dirty(bh
)) {
900 * First question: is this buffer already part of the current
901 * transaction or the existing committing transaction?
903 if (jh
->b_transaction
) {
905 jh
->b_transaction
== transaction
||
907 journal
->j_committing_transaction
);
908 if (jh
->b_next_transaction
)
909 J_ASSERT_JH(jh
, jh
->b_next_transaction
==
911 warn_dirty_buffer(bh
);
914 * In any case we need to clean the dirty flag and we must
915 * do it under the buffer lock to be sure we don't race
916 * with running write-out.
918 JBUFFER_TRACE(jh
, "Journalling dirty buffer");
919 clear_buffer_dirty(bh
);
920 set_buffer_jbddirty(bh
);
926 if (is_handle_aborted(handle
)) {
927 jbd_unlock_bh_state(bh
);
933 * The buffer is already part of this transaction if b_transaction or
934 * b_next_transaction points to it
936 if (jh
->b_transaction
== transaction
||
937 jh
->b_next_transaction
== transaction
)
941 * this is the first time this transaction is touching this buffer,
942 * reset the modified flag
947 * If the buffer is not journaled right now, we need to make sure it
948 * doesn't get written to disk before the caller actually commits the
951 if (!jh
->b_transaction
) {
952 JBUFFER_TRACE(jh
, "no transaction");
953 J_ASSERT_JH(jh
, !jh
->b_next_transaction
);
954 JBUFFER_TRACE(jh
, "file as BJ_Reserved");
956 * Make sure all stores to jh (b_modified, b_frozen_data) are
957 * visible before attaching it to the running transaction.
958 * Paired with barrier in jbd2_write_access_granted()
961 spin_lock(&journal
->j_list_lock
);
962 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Reserved
);
963 spin_unlock(&journal
->j_list_lock
);
967 * If there is already a copy-out version of this buffer, then we don't
968 * need to make another one
970 if (jh
->b_frozen_data
) {
971 JBUFFER_TRACE(jh
, "has frozen data");
972 J_ASSERT_JH(jh
, jh
->b_next_transaction
== NULL
);
976 JBUFFER_TRACE(jh
, "owned by older transaction");
977 J_ASSERT_JH(jh
, jh
->b_next_transaction
== NULL
);
978 J_ASSERT_JH(jh
, jh
->b_transaction
== journal
->j_committing_transaction
);
981 * There is one case we have to be very careful about. If the
982 * committing transaction is currently writing this buffer out to disk
983 * and has NOT made a copy-out, then we cannot modify the buffer
984 * contents at all right now. The essence of copy-out is that it is
985 * the extra copy, not the primary copy, which gets journaled. If the
986 * primary copy is already going to disk then we cannot do copy-out
989 if (buffer_shadow(bh
)) {
990 JBUFFER_TRACE(jh
, "on shadow: sleep");
991 jbd_unlock_bh_state(bh
);
992 wait_on_bit_io(&bh
->b_state
, BH_Shadow
, TASK_UNINTERRUPTIBLE
);
997 * Only do the copy if the currently-owning transaction still needs it.
998 * If buffer isn't on BJ_Metadata list, the committing transaction is
999 * past that stage (here we use the fact that BH_Shadow is set under
1000 * bh_state lock together with refiling to BJ_Shadow list and at this
1001 * point we know the buffer doesn't have BH_Shadow set).
1003 * Subtle point, though: if this is a get_undo_access, then we will be
1004 * relying on the frozen_data to contain the new value of the
1005 * committed_data record after the transaction, so we HAVE to force the
1006 * frozen_data copy in that case.
1008 if (jh
->b_jlist
== BJ_Metadata
|| force_copy
) {
1009 JBUFFER_TRACE(jh
, "generate frozen data");
1010 if (!frozen_buffer
) {
1011 JBUFFER_TRACE(jh
, "allocate memory for buffer");
1012 jbd_unlock_bh_state(bh
);
1013 frozen_buffer
= jbd2_alloc(jh2bh(jh
)->b_size
,
1014 GFP_NOFS
| __GFP_NOFAIL
);
1017 jh
->b_frozen_data
= frozen_buffer
;
1018 frozen_buffer
= NULL
;
1019 jbd2_freeze_jh_data(jh
);
1023 * Make sure all stores to jh (b_modified, b_frozen_data) are visible
1024 * before attaching it to the running transaction. Paired with barrier
1025 * in jbd2_write_access_granted()
1028 jh
->b_next_transaction
= transaction
;
1031 jbd_unlock_bh_state(bh
);
1034 * If we are about to journal a buffer, then any revoke pending on it is
1037 jbd2_journal_cancel_revoke(handle
, jh
);
1040 if (unlikely(frozen_buffer
)) /* It's usually NULL */
1041 jbd2_free(frozen_buffer
, bh
->b_size
);
1043 JBUFFER_TRACE(jh
, "exit");
1047 /* Fast check whether buffer is already attached to the required transaction */
1048 static bool jbd2_write_access_granted(handle_t
*handle
, struct buffer_head
*bh
,
1051 struct journal_head
*jh
;
1054 /* Dirty buffers require special handling... */
1055 if (buffer_dirty(bh
))
1059 * RCU protects us from dereferencing freed pages. So the checks we do
1060 * are guaranteed not to oops. However the jh slab object can get freed
1061 * & reallocated while we work with it. So we have to be careful. When
1062 * we see jh attached to the running transaction, we know it must stay
1063 * so until the transaction is committed. Thus jh won't be freed and
1064 * will be attached to the same bh while we run. However it can
1065 * happen jh gets freed, reallocated, and attached to the transaction
1066 * just after we get pointer to it from bh. So we have to be careful
1067 * and recheck jh still belongs to our bh before we return success.
1070 if (!buffer_jbd(bh
))
1072 /* This should be bh2jh() but that doesn't work with inline functions */
1073 jh
= READ_ONCE(bh
->b_private
);
1076 /* For undo access buffer must have data copied */
1077 if (undo
&& !jh
->b_committed_data
)
1079 if (jh
->b_transaction
!= handle
->h_transaction
&&
1080 jh
->b_next_transaction
!= handle
->h_transaction
)
1083 * There are two reasons for the barrier here:
1084 * 1) Make sure to fetch b_bh after we did previous checks so that we
1085 * detect when jh went through free, realloc, attach to transaction
1086 * while we were checking. Paired with implicit barrier in that path.
1087 * 2) So that access to bh done after jbd2_write_access_granted()
1088 * doesn't get reordered and see inconsistent state of concurrent
1089 * do_get_write_access().
1092 if (unlikely(jh
->b_bh
!= bh
))
1101 * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
1102 * @handle: transaction to add buffer modifications to
1103 * @bh: bh to be used for metadata writes
1105 * Returns: error code or 0 on success.
1107 * In full data journalling mode the buffer may be of type BJ_AsyncData,
1108 * because we're ``write()ing`` a buffer which is also part of a shared mapping.
1111 int jbd2_journal_get_write_access(handle_t
*handle
, struct buffer_head
*bh
)
1113 struct journal_head
*jh
;
1116 if (jbd2_write_access_granted(handle
, bh
, false))
1119 jh
= jbd2_journal_add_journal_head(bh
);
1120 /* We do not want to get caught playing with fields which the
1121 * log thread also manipulates. Make sure that the buffer
1122 * completes any outstanding IO before proceeding. */
1123 rc
= do_get_write_access(handle
, jh
, 0);
1124 jbd2_journal_put_journal_head(jh
);
1130 * When the user wants to journal a newly created buffer_head
1131 * (ie. getblk() returned a new buffer and we are going to populate it
1132 * manually rather than reading off disk), then we need to keep the
1133 * buffer_head locked until it has been completely filled with new
1134 * data. In this case, we should be able to make the assertion that
1135 * the bh is not already part of an existing transaction.
1137 * The buffer should already be locked by the caller by this point.
1138 * There is no lock ranking violation: it was a newly created,
1139 * unlocked buffer beforehand. */
1142 * int jbd2_journal_get_create_access () - notify intent to use newly created bh
1143 * @handle: transaction to new buffer to
1146 * Call this if you create a new bh.
1148 int jbd2_journal_get_create_access(handle_t
*handle
, struct buffer_head
*bh
)
1150 transaction_t
*transaction
= handle
->h_transaction
;
1152 struct journal_head
*jh
= jbd2_journal_add_journal_head(bh
);
1155 jbd_debug(5, "journal_head %p\n", jh
);
1157 if (is_handle_aborted(handle
))
1159 journal
= transaction
->t_journal
;
1162 JBUFFER_TRACE(jh
, "entry");
1164 * The buffer may already belong to this transaction due to pre-zeroing
1165 * in the filesystem's new_block code. It may also be on the previous,
1166 * committing transaction's lists, but it HAS to be in Forget state in
1167 * that case: the transaction must have deleted the buffer for it to be
1170 jbd_lock_bh_state(bh
);
1171 J_ASSERT_JH(jh
, (jh
->b_transaction
== transaction
||
1172 jh
->b_transaction
== NULL
||
1173 (jh
->b_transaction
== journal
->j_committing_transaction
&&
1174 jh
->b_jlist
== BJ_Forget
)));
1176 J_ASSERT_JH(jh
, jh
->b_next_transaction
== NULL
);
1177 J_ASSERT_JH(jh
, buffer_locked(jh2bh(jh
)));
1179 if (jh
->b_transaction
== NULL
) {
1181 * Previous jbd2_journal_forget() could have left the buffer
1182 * with jbddirty bit set because it was being committed. When
1183 * the commit finished, we've filed the buffer for
1184 * checkpointing and marked it dirty. Now we are reallocating
1185 * the buffer so the transaction freeing it must have
1186 * committed and so it's safe to clear the dirty bit.
1188 clear_buffer_dirty(jh2bh(jh
));
1189 /* first access by this transaction */
1192 JBUFFER_TRACE(jh
, "file as BJ_Reserved");
1193 spin_lock(&journal
->j_list_lock
);
1194 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Reserved
);
1195 spin_unlock(&journal
->j_list_lock
);
1196 } else if (jh
->b_transaction
== journal
->j_committing_transaction
) {
1197 /* first access by this transaction */
1200 JBUFFER_TRACE(jh
, "set next transaction");
1201 spin_lock(&journal
->j_list_lock
);
1202 jh
->b_next_transaction
= transaction
;
1203 spin_unlock(&journal
->j_list_lock
);
1205 jbd_unlock_bh_state(bh
);
1208 * akpm: I added this. ext3_alloc_branch can pick up new indirect
1209 * blocks which contain freed but then revoked metadata. We need
1210 * to cancel the revoke in case we end up freeing it yet again
1211 * and the reallocating as data - this would cause a second revoke,
1212 * which hits an assertion error.
1214 JBUFFER_TRACE(jh
, "cancelling revoke");
1215 jbd2_journal_cancel_revoke(handle
, jh
);
1217 jbd2_journal_put_journal_head(jh
);
1222 * int jbd2_journal_get_undo_access() - Notify intent to modify metadata with
1223 * non-rewindable consequences
1224 * @handle: transaction
1225 * @bh: buffer to undo
1227 * Sometimes there is a need to distinguish between metadata which has
1228 * been committed to disk and that which has not. The ext3fs code uses
1229 * this for freeing and allocating space, we have to make sure that we
1230 * do not reuse freed space until the deallocation has been committed,
1231 * since if we overwrote that space we would make the delete
1232 * un-rewindable in case of a crash.
1234 * To deal with that, jbd2_journal_get_undo_access requests write access to a
1235 * buffer for parts of non-rewindable operations such as delete
1236 * operations on the bitmaps. The journaling code must keep a copy of
1237 * the buffer's contents prior to the undo_access call until such time
1238 * as we know that the buffer has definitely been committed to disk.
1240 * We never need to know which transaction the committed data is part
1241 * of, buffers touched here are guaranteed to be dirtied later and so
1242 * will be committed to a new transaction in due course, at which point
1243 * we can discard the old committed data pointer.
1245 * Returns error number or 0 on success.
1247 int jbd2_journal_get_undo_access(handle_t
*handle
, struct buffer_head
*bh
)
1250 struct journal_head
*jh
;
1251 char *committed_data
= NULL
;
1253 if (jbd2_write_access_granted(handle
, bh
, true))
1256 jh
= jbd2_journal_add_journal_head(bh
);
1257 JBUFFER_TRACE(jh
, "entry");
1260 * Do this first --- it can drop the journal lock, so we want to
1261 * make sure that obtaining the committed_data is done
1262 * atomically wrt. completion of any outstanding commits.
1264 err
= do_get_write_access(handle
, jh
, 1);
1269 if (!jh
->b_committed_data
)
1270 committed_data
= jbd2_alloc(jh2bh(jh
)->b_size
,
1271 GFP_NOFS
|__GFP_NOFAIL
);
1273 jbd_lock_bh_state(bh
);
1274 if (!jh
->b_committed_data
) {
1275 /* Copy out the current buffer contents into the
1276 * preserved, committed copy. */
1277 JBUFFER_TRACE(jh
, "generate b_committed data");
1278 if (!committed_data
) {
1279 jbd_unlock_bh_state(bh
);
1283 jh
->b_committed_data
= committed_data
;
1284 committed_data
= NULL
;
1285 memcpy(jh
->b_committed_data
, bh
->b_data
, bh
->b_size
);
1287 jbd_unlock_bh_state(bh
);
1289 jbd2_journal_put_journal_head(jh
);
1290 if (unlikely(committed_data
))
1291 jbd2_free(committed_data
, bh
->b_size
);
1296 * void jbd2_journal_set_triggers() - Add triggers for commit writeout
1297 * @bh: buffer to trigger on
1298 * @type: struct jbd2_buffer_trigger_type containing the trigger(s).
1300 * Set any triggers on this journal_head. This is always safe, because
1301 * triggers for a committing buffer will be saved off, and triggers for
1302 * a running transaction will match the buffer in that transaction.
1304 * Call with NULL to clear the triggers.
1306 void jbd2_journal_set_triggers(struct buffer_head
*bh
,
1307 struct jbd2_buffer_trigger_type
*type
)
1309 struct journal_head
*jh
= jbd2_journal_grab_journal_head(bh
);
1313 jh
->b_triggers
= type
;
1314 jbd2_journal_put_journal_head(jh
);
1317 void jbd2_buffer_frozen_trigger(struct journal_head
*jh
, void *mapped_data
,
1318 struct jbd2_buffer_trigger_type
*triggers
)
1320 struct buffer_head
*bh
= jh2bh(jh
);
1322 if (!triggers
|| !triggers
->t_frozen
)
1325 triggers
->t_frozen(triggers
, bh
, mapped_data
, bh
->b_size
);
1328 void jbd2_buffer_abort_trigger(struct journal_head
*jh
,
1329 struct jbd2_buffer_trigger_type
*triggers
)
1331 if (!triggers
|| !triggers
->t_abort
)
1334 triggers
->t_abort(triggers
, jh2bh(jh
));
1338 * int jbd2_journal_dirty_metadata() - mark a buffer as containing dirty metadata
1339 * @handle: transaction to add buffer to.
1340 * @bh: buffer to mark
1342 * mark dirty metadata which needs to be journaled as part of the current
1345 * The buffer must have previously had jbd2_journal_get_write_access()
1346 * called so that it has a valid journal_head attached to the buffer
1349 * The buffer is placed on the transaction's metadata list and is marked
1350 * as belonging to the transaction.
1352 * Returns error number or 0 on success.
1354 * Special care needs to be taken if the buffer already belongs to the
1355 * current committing transaction (in which case we should have frozen
1356 * data present for that commit). In that case, we don't relink the
1357 * buffer: that only gets done when the old transaction finally
1358 * completes its commit.
1360 int jbd2_journal_dirty_metadata(handle_t
*handle
, struct buffer_head
*bh
)
1362 transaction_t
*transaction
= handle
->h_transaction
;
1364 struct journal_head
*jh
;
1367 if (is_handle_aborted(handle
))
1369 if (!buffer_jbd(bh
))
1373 * We don't grab jh reference here since the buffer must be part
1374 * of the running transaction.
1377 jbd_debug(5, "journal_head %p\n", jh
);
1378 JBUFFER_TRACE(jh
, "entry");
1381 * This and the following assertions are unreliable since we may see jh
1382 * in inconsistent state unless we grab bh_state lock. But this is
1383 * crucial to catch bugs so let's do a reliable check until the
1384 * lockless handling is fully proven.
1386 if (jh
->b_transaction
!= transaction
&&
1387 jh
->b_next_transaction
!= transaction
) {
1388 jbd_lock_bh_state(bh
);
1389 J_ASSERT_JH(jh
, jh
->b_transaction
== transaction
||
1390 jh
->b_next_transaction
== transaction
);
1391 jbd_unlock_bh_state(bh
);
1393 if (jh
->b_modified
== 1) {
1394 /* If it's in our transaction it must be in BJ_Metadata list. */
1395 if (jh
->b_transaction
== transaction
&&
1396 jh
->b_jlist
!= BJ_Metadata
) {
1397 jbd_lock_bh_state(bh
);
1398 if (jh
->b_transaction
== transaction
&&
1399 jh
->b_jlist
!= BJ_Metadata
)
1400 pr_err("JBD2: assertion failure: h_type=%u "
1401 "h_line_no=%u block_no=%llu jlist=%u\n",
1402 handle
->h_type
, handle
->h_line_no
,
1403 (unsigned long long) bh
->b_blocknr
,
1405 J_ASSERT_JH(jh
, jh
->b_transaction
!= transaction
||
1406 jh
->b_jlist
== BJ_Metadata
);
1407 jbd_unlock_bh_state(bh
);
1412 journal
= transaction
->t_journal
;
1413 jbd_lock_bh_state(bh
);
1415 if (jh
->b_modified
== 0) {
1417 * This buffer's got modified and becoming part
1418 * of the transaction. This needs to be done
1419 * once a transaction -bzzz
1421 if (handle
->h_buffer_credits
<= 0) {
1426 handle
->h_buffer_credits
--;
1430 * fastpath, to avoid expensive locking. If this buffer is already
1431 * on the running transaction's metadata list there is nothing to do.
1432 * Nobody can take it off again because there is a handle open.
1433 * I _think_ we're OK here with SMP barriers - a mistaken decision will
1434 * result in this test being false, so we go in and take the locks.
1436 if (jh
->b_transaction
== transaction
&& jh
->b_jlist
== BJ_Metadata
) {
1437 JBUFFER_TRACE(jh
, "fastpath");
1438 if (unlikely(jh
->b_transaction
!=
1439 journal
->j_running_transaction
)) {
1440 printk(KERN_ERR
"JBD2: %s: "
1441 "jh->b_transaction (%llu, %p, %u) != "
1442 "journal->j_running_transaction (%p, %u)\n",
1444 (unsigned long long) bh
->b_blocknr
,
1446 jh
->b_transaction
? jh
->b_transaction
->t_tid
: 0,
1447 journal
->j_running_transaction
,
1448 journal
->j_running_transaction
?
1449 journal
->j_running_transaction
->t_tid
: 0);
1455 set_buffer_jbddirty(bh
);
1458 * Metadata already on the current transaction list doesn't
1459 * need to be filed. Metadata on another transaction's list must
1460 * be committing, and will be refiled once the commit completes:
1461 * leave it alone for now.
1463 if (jh
->b_transaction
!= transaction
) {
1464 JBUFFER_TRACE(jh
, "already on other transaction");
1465 if (unlikely(((jh
->b_transaction
!=
1466 journal
->j_committing_transaction
)) ||
1467 (jh
->b_next_transaction
!= transaction
))) {
1468 printk(KERN_ERR
"jbd2_journal_dirty_metadata: %s: "
1469 "bad jh for block %llu: "
1470 "transaction (%p, %u), "
1471 "jh->b_transaction (%p, %u), "
1472 "jh->b_next_transaction (%p, %u), jlist %u\n",
1474 (unsigned long long) bh
->b_blocknr
,
1475 transaction
, transaction
->t_tid
,
1478 jh
->b_transaction
->t_tid
: 0,
1479 jh
->b_next_transaction
,
1480 jh
->b_next_transaction
?
1481 jh
->b_next_transaction
->t_tid
: 0,
1486 /* And this case is illegal: we can't reuse another
1487 * transaction's data buffer, ever. */
1491 /* That test should have eliminated the following case: */
1492 J_ASSERT_JH(jh
, jh
->b_frozen_data
== NULL
);
1494 JBUFFER_TRACE(jh
, "file as BJ_Metadata");
1495 spin_lock(&journal
->j_list_lock
);
1496 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Metadata
);
1497 spin_unlock(&journal
->j_list_lock
);
1499 jbd_unlock_bh_state(bh
);
1501 JBUFFER_TRACE(jh
, "exit");
1506 * void jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1507 * @handle: transaction handle
1508 * @bh: bh to 'forget'
1510 * We can only do the bforget if there are no commits pending against the
1511 * buffer. If the buffer is dirty in the current running transaction we
1512 * can safely unlink it.
1514 * bh may not be a journalled buffer at all - it may be a non-JBD
1515 * buffer which came off the hashtable. Check for this.
1517 * Decrements bh->b_count by one.
1519 * Allow this call even if the handle has aborted --- it may be part of
1520 * the caller's cleanup after an abort.
1522 int jbd2_journal_forget (handle_t
*handle
, struct buffer_head
*bh
)
1524 transaction_t
*transaction
= handle
->h_transaction
;
1526 struct journal_head
*jh
;
1527 int drop_reserve
= 0;
1529 int was_modified
= 0;
1531 if (is_handle_aborted(handle
))
1533 journal
= transaction
->t_journal
;
1535 BUFFER_TRACE(bh
, "entry");
1537 jbd_lock_bh_state(bh
);
1539 if (!buffer_jbd(bh
))
1543 /* Critical error: attempting to delete a bitmap buffer, maybe?
1544 * Don't do any jbd operations, and return an error. */
1545 if (!J_EXPECT_JH(jh
, !jh
->b_committed_data
,
1546 "inconsistent data on disk")) {
1551 /* keep track of whether or not this transaction modified us */
1552 was_modified
= jh
->b_modified
;
1555 * The buffer's going from the transaction, we must drop
1556 * all references -bzzz
1560 if (jh
->b_transaction
== transaction
) {
1561 J_ASSERT_JH(jh
, !jh
->b_frozen_data
);
1563 /* If we are forgetting a buffer which is already part
1564 * of this transaction, then we can just drop it from
1565 * the transaction immediately. */
1566 clear_buffer_dirty(bh
);
1567 clear_buffer_jbddirty(bh
);
1569 JBUFFER_TRACE(jh
, "belongs to current transaction: unfile");
1572 * we only want to drop a reference if this transaction
1573 * modified the buffer
1579 * We are no longer going to journal this buffer.
1580 * However, the commit of this transaction is still
1581 * important to the buffer: the delete that we are now
1582 * processing might obsolete an old log entry, so by
1583 * committing, we can satisfy the buffer's checkpoint.
1585 * So, if we have a checkpoint on the buffer, we should
1586 * now refile the buffer on our BJ_Forget list so that
1587 * we know to remove the checkpoint after we commit.
1590 spin_lock(&journal
->j_list_lock
);
1591 if (jh
->b_cp_transaction
) {
1592 __jbd2_journal_temp_unlink_buffer(jh
);
1593 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Forget
);
1595 __jbd2_journal_unfile_buffer(jh
);
1596 if (!buffer_jbd(bh
)) {
1597 spin_unlock(&journal
->j_list_lock
);
1601 spin_unlock(&journal
->j_list_lock
);
1602 } else if (jh
->b_transaction
) {
1603 J_ASSERT_JH(jh
, (jh
->b_transaction
==
1604 journal
->j_committing_transaction
));
1605 /* However, if the buffer is still owned by a prior
1606 * (committing) transaction, we can't drop it yet... */
1607 JBUFFER_TRACE(jh
, "belongs to older transaction");
1608 /* ... but we CAN drop it from the new transaction through
1609 * marking the buffer as freed and set j_next_transaction to
1610 * the new transaction, so that not only the commit code
1611 * knows it should clear dirty bits when it is done with the
1612 * buffer, but also the buffer can be checkpointed only
1613 * after the new transaction commits. */
1615 set_buffer_freed(bh
);
1617 if (!jh
->b_next_transaction
) {
1618 spin_lock(&journal
->j_list_lock
);
1619 jh
->b_next_transaction
= transaction
;
1620 spin_unlock(&journal
->j_list_lock
);
1622 J_ASSERT(jh
->b_next_transaction
== transaction
);
1625 * only drop a reference if this transaction modified
1633 * Finally, if the buffer is not belongs to any
1634 * transaction, we can just drop it now if it has no
1637 spin_lock(&journal
->j_list_lock
);
1638 if (!jh
->b_cp_transaction
) {
1639 JBUFFER_TRACE(jh
, "belongs to none transaction");
1640 spin_unlock(&journal
->j_list_lock
);
1645 * Otherwise, if the buffer has been written to disk,
1646 * it is safe to remove the checkpoint and drop it.
1648 if (!buffer_dirty(bh
)) {
1649 __jbd2_journal_remove_checkpoint(jh
);
1650 spin_unlock(&journal
->j_list_lock
);
1655 * The buffer is still not written to disk, we should
1656 * attach this buffer to current transaction so that the
1657 * buffer can be checkpointed only after the current
1658 * transaction commits.
1660 clear_buffer_dirty(bh
);
1661 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Forget
);
1662 spin_unlock(&journal
->j_list_lock
);
1665 jbd_unlock_bh_state(bh
);
1669 /* no need to reserve log space for this block -bzzz */
1670 handle
->h_buffer_credits
++;
1675 jbd_unlock_bh_state(bh
);
1681 * int jbd2_journal_stop() - complete a transaction
1682 * @handle: transaction to complete.
1684 * All done for a particular handle.
1686 * There is not much action needed here. We just return any remaining
1687 * buffer credits to the transaction and remove the handle. The only
1688 * complication is that we need to start a commit operation if the
1689 * filesystem is marked for synchronous update.
1691 * jbd2_journal_stop itself will not usually return an error, but it may
1692 * do so in unusual circumstances. In particular, expect it to
1693 * return -EIO if a jbd2_journal_abort has been executed since the
1694 * transaction began.
1696 int jbd2_journal_stop(handle_t
*handle
)
1698 transaction_t
*transaction
= handle
->h_transaction
;
1700 int err
= 0, wait_for_commit
= 0;
1706 * Handle is already detached from the transaction so
1707 * there is nothing to do other than decrease a refcount,
1708 * or free the handle if refcount drops to zero
1710 if (--handle
->h_ref
> 0) {
1711 jbd_debug(4, "h_ref %d -> %d\n", handle
->h_ref
+ 1,
1715 if (handle
->h_rsv_handle
)
1716 jbd2_free_handle(handle
->h_rsv_handle
);
1720 journal
= transaction
->t_journal
;
1722 J_ASSERT(journal_current_handle() == handle
);
1724 if (is_handle_aborted(handle
))
1727 J_ASSERT(atomic_read(&transaction
->t_updates
) > 0);
1729 if (--handle
->h_ref
> 0) {
1730 jbd_debug(4, "h_ref %d -> %d\n", handle
->h_ref
+ 1,
1735 jbd_debug(4, "Handle %p going down\n", handle
);
1736 trace_jbd2_handle_stats(journal
->j_fs_dev
->bd_dev
,
1738 handle
->h_type
, handle
->h_line_no
,
1739 jiffies
- handle
->h_start_jiffies
,
1740 handle
->h_sync
, handle
->h_requested_credits
,
1741 (handle
->h_requested_credits
-
1742 handle
->h_buffer_credits
));
1745 * Implement synchronous transaction batching. If the handle
1746 * was synchronous, don't force a commit immediately. Let's
1747 * yield and let another thread piggyback onto this
1748 * transaction. Keep doing that while new threads continue to
1749 * arrive. It doesn't cost much - we're about to run a commit
1750 * and sleep on IO anyway. Speeds up many-threaded, many-dir
1751 * operations by 30x or more...
1753 * We try and optimize the sleep time against what the
1754 * underlying disk can do, instead of having a static sleep
1755 * time. This is useful for the case where our storage is so
1756 * fast that it is more optimal to go ahead and force a flush
1757 * and wait for the transaction to be committed than it is to
1758 * wait for an arbitrary amount of time for new writers to
1759 * join the transaction. We achieve this by measuring how
1760 * long it takes to commit a transaction, and compare it with
1761 * how long this transaction has been running, and if run time
1762 * < commit time then we sleep for the delta and commit. This
1763 * greatly helps super fast disks that would see slowdowns as
1764 * more threads started doing fsyncs.
1766 * But don't do this if this process was the most recent one
1767 * to perform a synchronous write. We do this to detect the
1768 * case where a single process is doing a stream of sync
1769 * writes. No point in waiting for joiners in that case.
1771 * Setting max_batch_time to 0 disables this completely.
1774 if (handle
->h_sync
&& journal
->j_last_sync_writer
!= pid
&&
1775 journal
->j_max_batch_time
) {
1776 u64 commit_time
, trans_time
;
1778 journal
->j_last_sync_writer
= pid
;
1780 read_lock(&journal
->j_state_lock
);
1781 commit_time
= journal
->j_average_commit_time
;
1782 read_unlock(&journal
->j_state_lock
);
1784 trans_time
= ktime_to_ns(ktime_sub(ktime_get(),
1785 transaction
->t_start_time
));
1787 commit_time
= max_t(u64
, commit_time
,
1788 1000*journal
->j_min_batch_time
);
1789 commit_time
= min_t(u64
, commit_time
,
1790 1000*journal
->j_max_batch_time
);
1792 if (trans_time
< commit_time
) {
1793 ktime_t expires
= ktime_add_ns(ktime_get(),
1795 set_current_state(TASK_UNINTERRUPTIBLE
);
1796 schedule_hrtimeout(&expires
, HRTIMER_MODE_ABS
);
1801 transaction
->t_synchronous_commit
= 1;
1802 current
->journal_info
= NULL
;
1803 atomic_sub(handle
->h_buffer_credits
,
1804 &transaction
->t_outstanding_credits
);
1807 * If the handle is marked SYNC, we need to set another commit
1808 * going! We also want to force a commit if the current
1809 * transaction is occupying too much of the log, or if the
1810 * transaction is too old now.
1812 if (handle
->h_sync
||
1813 (atomic_read(&transaction
->t_outstanding_credits
) >
1814 journal
->j_max_transaction_buffers
) ||
1815 time_after_eq(jiffies
, transaction
->t_expires
)) {
1816 /* Do this even for aborted journals: an abort still
1817 * completes the commit thread, it just doesn't write
1818 * anything to disk. */
1820 jbd_debug(2, "transaction too old, requesting commit for "
1821 "handle %p\n", handle
);
1822 /* This is non-blocking */
1823 jbd2_log_start_commit(journal
, transaction
->t_tid
);
1826 * Special case: JBD2_SYNC synchronous updates require us
1827 * to wait for the commit to complete.
1829 if (handle
->h_sync
&& !(current
->flags
& PF_MEMALLOC
))
1830 wait_for_commit
= 1;
1834 * Once we drop t_updates, if it goes to zero the transaction
1835 * could start committing on us and eventually disappear. So
1836 * once we do this, we must not dereference transaction
1839 tid
= transaction
->t_tid
;
1840 if (atomic_dec_and_test(&transaction
->t_updates
)) {
1841 wake_up(&journal
->j_wait_updates
);
1842 if (journal
->j_barrier_count
)
1843 wake_up(&journal
->j_wait_transaction_locked
);
1846 rwsem_release(&journal
->j_trans_commit_map
, 1, _THIS_IP_
);
1848 if (wait_for_commit
)
1849 err
= jbd2_log_wait_commit(journal
, tid
);
1851 if (handle
->h_rsv_handle
)
1852 jbd2_journal_free_reserved(handle
->h_rsv_handle
);
1855 * Scope of the GFP_NOFS context is over here and so we can restore the
1856 * original alloc context.
1858 memalloc_nofs_restore(handle
->saved_alloc_context
);
1859 jbd2_free_handle(handle
);
1865 * List management code snippets: various functions for manipulating the
1866 * transaction buffer lists.
1871 * Append a buffer to a transaction list, given the transaction's list head
1874 * j_list_lock is held.
1876 * jbd_lock_bh_state(jh2bh(jh)) is held.
1880 __blist_add_buffer(struct journal_head
**list
, struct journal_head
*jh
)
1883 jh
->b_tnext
= jh
->b_tprev
= jh
;
1886 /* Insert at the tail of the list to preserve order */
1887 struct journal_head
*first
= *list
, *last
= first
->b_tprev
;
1889 jh
->b_tnext
= first
;
1890 last
->b_tnext
= first
->b_tprev
= jh
;
1895 * Remove a buffer from a transaction list, given the transaction's list
1898 * Called with j_list_lock held, and the journal may not be locked.
1900 * jbd_lock_bh_state(jh2bh(jh)) is held.
1904 __blist_del_buffer(struct journal_head
**list
, struct journal_head
*jh
)
1907 *list
= jh
->b_tnext
;
1911 jh
->b_tprev
->b_tnext
= jh
->b_tnext
;
1912 jh
->b_tnext
->b_tprev
= jh
->b_tprev
;
1916 * Remove a buffer from the appropriate transaction list.
1918 * Note that this function can *change* the value of
1919 * bh->b_transaction->t_buffers, t_forget, t_shadow_list, t_log_list or
1920 * t_reserved_list. If the caller is holding onto a copy of one of these
1921 * pointers, it could go bad. Generally the caller needs to re-read the
1922 * pointer from the transaction_t.
1924 * Called under j_list_lock.
1926 static void __jbd2_journal_temp_unlink_buffer(struct journal_head
*jh
)
1928 struct journal_head
**list
= NULL
;
1929 transaction_t
*transaction
;
1930 struct buffer_head
*bh
= jh2bh(jh
);
1932 J_ASSERT_JH(jh
, jbd_is_locked_bh_state(bh
));
1933 transaction
= jh
->b_transaction
;
1935 assert_spin_locked(&transaction
->t_journal
->j_list_lock
);
1937 J_ASSERT_JH(jh
, jh
->b_jlist
< BJ_Types
);
1938 if (jh
->b_jlist
!= BJ_None
)
1939 J_ASSERT_JH(jh
, transaction
!= NULL
);
1941 switch (jh
->b_jlist
) {
1945 transaction
->t_nr_buffers
--;
1946 J_ASSERT_JH(jh
, transaction
->t_nr_buffers
>= 0);
1947 list
= &transaction
->t_buffers
;
1950 list
= &transaction
->t_forget
;
1953 list
= &transaction
->t_shadow_list
;
1956 list
= &transaction
->t_reserved_list
;
1960 __blist_del_buffer(list
, jh
);
1961 jh
->b_jlist
= BJ_None
;
1962 if (transaction
&& is_journal_aborted(transaction
->t_journal
))
1963 clear_buffer_jbddirty(bh
);
1964 else if (test_clear_buffer_jbddirty(bh
))
1965 mark_buffer_dirty(bh
); /* Expose it to the VM */
1969 * Remove buffer from all transactions.
1971 * Called with bh_state lock and j_list_lock
1973 * jh and bh may be already freed when this function returns.
1975 static void __jbd2_journal_unfile_buffer(struct journal_head
*jh
)
1977 __jbd2_journal_temp_unlink_buffer(jh
);
1978 jh
->b_transaction
= NULL
;
1979 jbd2_journal_put_journal_head(jh
);
1982 void jbd2_journal_unfile_buffer(journal_t
*journal
, struct journal_head
*jh
)
1984 struct buffer_head
*bh
= jh2bh(jh
);
1986 /* Get reference so that buffer cannot be freed before we unlock it */
1988 jbd_lock_bh_state(bh
);
1989 spin_lock(&journal
->j_list_lock
);
1990 __jbd2_journal_unfile_buffer(jh
);
1991 spin_unlock(&journal
->j_list_lock
);
1992 jbd_unlock_bh_state(bh
);
1997 * Called from jbd2_journal_try_to_free_buffers().
1999 * Called under jbd_lock_bh_state(bh)
2002 __journal_try_to_free_buffer(journal_t
*journal
, struct buffer_head
*bh
)
2004 struct journal_head
*jh
;
2008 if (buffer_locked(bh
) || buffer_dirty(bh
))
2011 if (jh
->b_next_transaction
!= NULL
|| jh
->b_transaction
!= NULL
)
2014 spin_lock(&journal
->j_list_lock
);
2015 if (jh
->b_cp_transaction
!= NULL
) {
2016 /* written-back checkpointed metadata buffer */
2017 JBUFFER_TRACE(jh
, "remove from checkpoint list");
2018 __jbd2_journal_remove_checkpoint(jh
);
2020 spin_unlock(&journal
->j_list_lock
);
2026 * int jbd2_journal_try_to_free_buffers() - try to free page buffers.
2027 * @journal: journal for operation
2028 * @page: to try and free
2029 * @gfp_mask: we use the mask to detect how hard should we try to release
2030 * buffers. If __GFP_DIRECT_RECLAIM and __GFP_FS is set, we wait for commit
2031 * code to release the buffers.
2034 * For all the buffers on this page,
2035 * if they are fully written out ordered data, move them onto BUF_CLEAN
2036 * so try_to_free_buffers() can reap them.
2038 * This function returns non-zero if we wish try_to_free_buffers()
2039 * to be called. We do this if the page is releasable by try_to_free_buffers().
2040 * We also do it if the page has locked or dirty buffers and the caller wants
2041 * us to perform sync or async writeout.
2043 * This complicates JBD locking somewhat. We aren't protected by the
2044 * BKL here. We wish to remove the buffer from its committing or
2045 * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
2047 * This may *change* the value of transaction_t->t_datalist, so anyone
2048 * who looks at t_datalist needs to lock against this function.
2050 * Even worse, someone may be doing a jbd2_journal_dirty_data on this
2051 * buffer. So we need to lock against that. jbd2_journal_dirty_data()
2052 * will come out of the lock with the buffer dirty, which makes it
2053 * ineligible for release here.
2055 * Who else is affected by this? hmm... Really the only contender
2056 * is do_get_write_access() - it could be looking at the buffer while
2057 * journal_try_to_free_buffer() is changing its state. But that
2058 * cannot happen because we never reallocate freed data as metadata
2059 * while the data is part of a transaction. Yes?
2061 * Return 0 on failure, 1 on success
2063 int jbd2_journal_try_to_free_buffers(journal_t
*journal
,
2064 struct page
*page
, gfp_t gfp_mask
)
2066 struct buffer_head
*head
;
2067 struct buffer_head
*bh
;
2070 J_ASSERT(PageLocked(page
));
2072 head
= page_buffers(page
);
2075 struct journal_head
*jh
;
2078 * We take our own ref against the journal_head here to avoid
2079 * having to add tons of locking around each instance of
2080 * jbd2_journal_put_journal_head().
2082 jh
= jbd2_journal_grab_journal_head(bh
);
2086 jbd_lock_bh_state(bh
);
2087 __journal_try_to_free_buffer(journal
, bh
);
2088 jbd2_journal_put_journal_head(jh
);
2089 jbd_unlock_bh_state(bh
);
2092 } while ((bh
= bh
->b_this_page
) != head
);
2094 ret
= try_to_free_buffers(page
);
2101 * This buffer is no longer needed. If it is on an older transaction's
2102 * checkpoint list we need to record it on this transaction's forget list
2103 * to pin this buffer (and hence its checkpointing transaction) down until
2104 * this transaction commits. If the buffer isn't on a checkpoint list, we
2106 * Returns non-zero if JBD no longer has an interest in the buffer.
2108 * Called under j_list_lock.
2110 * Called under jbd_lock_bh_state(bh).
2112 static int __dispose_buffer(struct journal_head
*jh
, transaction_t
*transaction
)
2115 struct buffer_head
*bh
= jh2bh(jh
);
2117 if (jh
->b_cp_transaction
) {
2118 JBUFFER_TRACE(jh
, "on running+cp transaction");
2119 __jbd2_journal_temp_unlink_buffer(jh
);
2121 * We don't want to write the buffer anymore, clear the
2122 * bit so that we don't confuse checks in
2123 * __journal_file_buffer
2125 clear_buffer_dirty(bh
);
2126 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Forget
);
2129 JBUFFER_TRACE(jh
, "on running transaction");
2130 __jbd2_journal_unfile_buffer(jh
);
2136 * jbd2_journal_invalidatepage
2138 * This code is tricky. It has a number of cases to deal with.
2140 * There are two invariants which this code relies on:
2142 * i_size must be updated on disk before we start calling invalidatepage on the
2145 * This is done in ext3 by defining an ext3_setattr method which
2146 * updates i_size before truncate gets going. By maintaining this
2147 * invariant, we can be sure that it is safe to throw away any buffers
2148 * attached to the current transaction: once the transaction commits,
2149 * we know that the data will not be needed.
2151 * Note however that we can *not* throw away data belonging to the
2152 * previous, committing transaction!
2154 * Any disk blocks which *are* part of the previous, committing
2155 * transaction (and which therefore cannot be discarded immediately) are
2156 * not going to be reused in the new running transaction
2158 * The bitmap committed_data images guarantee this: any block which is
2159 * allocated in one transaction and removed in the next will be marked
2160 * as in-use in the committed_data bitmap, so cannot be reused until
2161 * the next transaction to delete the block commits. This means that
2162 * leaving committing buffers dirty is quite safe: the disk blocks
2163 * cannot be reallocated to a different file and so buffer aliasing is
2167 * The above applies mainly to ordered data mode. In writeback mode we
2168 * don't make guarantees about the order in which data hits disk --- in
2169 * particular we don't guarantee that new dirty data is flushed before
2170 * transaction commit --- so it is always safe just to discard data
2171 * immediately in that mode. --sct
2175 * The journal_unmap_buffer helper function returns zero if the buffer
2176 * concerned remains pinned as an anonymous buffer belonging to an older
2179 * We're outside-transaction here. Either or both of j_running_transaction
2180 * and j_committing_transaction may be NULL.
2182 static int journal_unmap_buffer(journal_t
*journal
, struct buffer_head
*bh
,
2185 transaction_t
*transaction
;
2186 struct journal_head
*jh
;
2189 BUFFER_TRACE(bh
, "entry");
2192 * It is safe to proceed here without the j_list_lock because the
2193 * buffers cannot be stolen by try_to_free_buffers as long as we are
2194 * holding the page lock. --sct
2197 if (!buffer_jbd(bh
))
2198 goto zap_buffer_unlocked
;
2200 /* OK, we have data buffer in journaled mode */
2201 write_lock(&journal
->j_state_lock
);
2202 jbd_lock_bh_state(bh
);
2203 spin_lock(&journal
->j_list_lock
);
2205 jh
= jbd2_journal_grab_journal_head(bh
);
2207 goto zap_buffer_no_jh
;
2210 * We cannot remove the buffer from checkpoint lists until the
2211 * transaction adding inode to orphan list (let's call it T)
2212 * is committed. Otherwise if the transaction changing the
2213 * buffer would be cleaned from the journal before T is
2214 * committed, a crash will cause that the correct contents of
2215 * the buffer will be lost. On the other hand we have to
2216 * clear the buffer dirty bit at latest at the moment when the
2217 * transaction marking the buffer as freed in the filesystem
2218 * structures is committed because from that moment on the
2219 * block can be reallocated and used by a different page.
2220 * Since the block hasn't been freed yet but the inode has
2221 * already been added to orphan list, it is safe for us to add
2222 * the buffer to BJ_Forget list of the newest transaction.
2224 * Also we have to clear buffer_mapped flag of a truncated buffer
2225 * because the buffer_head may be attached to the page straddling
2226 * i_size (can happen only when blocksize < pagesize) and thus the
2227 * buffer_head can be reused when the file is extended again. So we end
2228 * up keeping around invalidated buffers attached to transactions'
2229 * BJ_Forget list just to stop checkpointing code from cleaning up
2230 * the transaction this buffer was modified in.
2232 transaction
= jh
->b_transaction
;
2233 if (transaction
== NULL
) {
2234 /* First case: not on any transaction. If it
2235 * has no checkpoint link, then we can zap it:
2236 * it's a writeback-mode buffer so we don't care
2237 * if it hits disk safely. */
2238 if (!jh
->b_cp_transaction
) {
2239 JBUFFER_TRACE(jh
, "not on any transaction: zap");
2243 if (!buffer_dirty(bh
)) {
2244 /* bdflush has written it. We can drop it now */
2245 __jbd2_journal_remove_checkpoint(jh
);
2249 /* OK, it must be in the journal but still not
2250 * written fully to disk: it's metadata or
2251 * journaled data... */
2253 if (journal
->j_running_transaction
) {
2254 /* ... and once the current transaction has
2255 * committed, the buffer won't be needed any
2257 JBUFFER_TRACE(jh
, "checkpointed: add to BJ_Forget");
2258 may_free
= __dispose_buffer(jh
,
2259 journal
->j_running_transaction
);
2262 /* There is no currently-running transaction. So the
2263 * orphan record which we wrote for this file must have
2264 * passed into commit. We must attach this buffer to
2265 * the committing transaction, if it exists. */
2266 if (journal
->j_committing_transaction
) {
2267 JBUFFER_TRACE(jh
, "give to committing trans");
2268 may_free
= __dispose_buffer(jh
,
2269 journal
->j_committing_transaction
);
2272 /* The orphan record's transaction has
2273 * committed. We can cleanse this buffer */
2274 clear_buffer_jbddirty(bh
);
2275 __jbd2_journal_remove_checkpoint(jh
);
2279 } else if (transaction
== journal
->j_committing_transaction
) {
2280 JBUFFER_TRACE(jh
, "on committing transaction");
2282 * The buffer is committing, we simply cannot touch
2283 * it. If the page is straddling i_size we have to wait
2284 * for commit and try again.
2287 jbd2_journal_put_journal_head(jh
);
2288 spin_unlock(&journal
->j_list_lock
);
2289 jbd_unlock_bh_state(bh
);
2290 write_unlock(&journal
->j_state_lock
);
2294 * OK, buffer won't be reachable after truncate. We just set
2295 * j_next_transaction to the running transaction (if there is
2296 * one) and mark buffer as freed so that commit code knows it
2297 * should clear dirty bits when it is done with the buffer.
2299 set_buffer_freed(bh
);
2300 if (journal
->j_running_transaction
&& buffer_jbddirty(bh
))
2301 jh
->b_next_transaction
= journal
->j_running_transaction
;
2302 jbd2_journal_put_journal_head(jh
);
2303 spin_unlock(&journal
->j_list_lock
);
2304 jbd_unlock_bh_state(bh
);
2305 write_unlock(&journal
->j_state_lock
);
2308 /* Good, the buffer belongs to the running transaction.
2309 * We are writing our own transaction's data, not any
2310 * previous one's, so it is safe to throw it away
2311 * (remember that we expect the filesystem to have set
2312 * i_size already for this truncate so recovery will not
2313 * expose the disk blocks we are discarding here.) */
2314 J_ASSERT_JH(jh
, transaction
== journal
->j_running_transaction
);
2315 JBUFFER_TRACE(jh
, "on running transaction");
2316 may_free
= __dispose_buffer(jh
, transaction
);
2321 * This is tricky. Although the buffer is truncated, it may be reused
2322 * if blocksize < pagesize and it is attached to the page straddling
2323 * EOF. Since the buffer might have been added to BJ_Forget list of the
2324 * running transaction, journal_get_write_access() won't clear
2325 * b_modified and credit accounting gets confused. So clear b_modified
2329 jbd2_journal_put_journal_head(jh
);
2331 spin_unlock(&journal
->j_list_lock
);
2332 jbd_unlock_bh_state(bh
);
2333 write_unlock(&journal
->j_state_lock
);
2334 zap_buffer_unlocked
:
2335 clear_buffer_dirty(bh
);
2336 J_ASSERT_BH(bh
, !buffer_jbddirty(bh
));
2337 clear_buffer_mapped(bh
);
2338 clear_buffer_req(bh
);
2339 clear_buffer_new(bh
);
2340 clear_buffer_delay(bh
);
2341 clear_buffer_unwritten(bh
);
2347 * void jbd2_journal_invalidatepage()
2348 * @journal: journal to use for flush...
2349 * @page: page to flush
2350 * @offset: start of the range to invalidate
2351 * @length: length of the range to invalidate
2353 * Reap page buffers containing data after in the specified range in page.
2354 * Can return -EBUSY if buffers are part of the committing transaction and
2355 * the page is straddling i_size. Caller then has to wait for current commit
2358 int jbd2_journal_invalidatepage(journal_t
*journal
,
2360 unsigned int offset
,
2361 unsigned int length
)
2363 struct buffer_head
*head
, *bh
, *next
;
2364 unsigned int stop
= offset
+ length
;
2365 unsigned int curr_off
= 0;
2366 int partial_page
= (offset
|| length
< PAGE_SIZE
);
2370 if (!PageLocked(page
))
2372 if (!page_has_buffers(page
))
2375 BUG_ON(stop
> PAGE_SIZE
|| stop
< length
);
2377 /* We will potentially be playing with lists other than just the
2378 * data lists (especially for journaled data mode), so be
2379 * cautious in our locking. */
2381 head
= bh
= page_buffers(page
);
2383 unsigned int next_off
= curr_off
+ bh
->b_size
;
2384 next
= bh
->b_this_page
;
2386 if (next_off
> stop
)
2389 if (offset
<= curr_off
) {
2390 /* This block is wholly outside the truncation point */
2392 ret
= journal_unmap_buffer(journal
, bh
, partial_page
);
2398 curr_off
= next_off
;
2401 } while (bh
!= head
);
2403 if (!partial_page
) {
2404 if (may_free
&& try_to_free_buffers(page
))
2405 J_ASSERT(!page_has_buffers(page
));
2411 * File a buffer on the given transaction list.
2413 void __jbd2_journal_file_buffer(struct journal_head
*jh
,
2414 transaction_t
*transaction
, int jlist
)
2416 struct journal_head
**list
= NULL
;
2418 struct buffer_head
*bh
= jh2bh(jh
);
2420 J_ASSERT_JH(jh
, jbd_is_locked_bh_state(bh
));
2421 assert_spin_locked(&transaction
->t_journal
->j_list_lock
);
2423 J_ASSERT_JH(jh
, jh
->b_jlist
< BJ_Types
);
2424 J_ASSERT_JH(jh
, jh
->b_transaction
== transaction
||
2425 jh
->b_transaction
== NULL
);
2427 if (jh
->b_transaction
&& jh
->b_jlist
== jlist
)
2430 if (jlist
== BJ_Metadata
|| jlist
== BJ_Reserved
||
2431 jlist
== BJ_Shadow
|| jlist
== BJ_Forget
) {
2433 * For metadata buffers, we track dirty bit in buffer_jbddirty
2434 * instead of buffer_dirty. We should not see a dirty bit set
2435 * here because we clear it in do_get_write_access but e.g.
2436 * tune2fs can modify the sb and set the dirty bit at any time
2437 * so we try to gracefully handle that.
2439 if (buffer_dirty(bh
))
2440 warn_dirty_buffer(bh
);
2441 if (test_clear_buffer_dirty(bh
) ||
2442 test_clear_buffer_jbddirty(bh
))
2446 if (jh
->b_transaction
)
2447 __jbd2_journal_temp_unlink_buffer(jh
);
2449 jbd2_journal_grab_journal_head(bh
);
2450 jh
->b_transaction
= transaction
;
2454 J_ASSERT_JH(jh
, !jh
->b_committed_data
);
2455 J_ASSERT_JH(jh
, !jh
->b_frozen_data
);
2458 transaction
->t_nr_buffers
++;
2459 list
= &transaction
->t_buffers
;
2462 list
= &transaction
->t_forget
;
2465 list
= &transaction
->t_shadow_list
;
2468 list
= &transaction
->t_reserved_list
;
2472 __blist_add_buffer(list
, jh
);
2473 jh
->b_jlist
= jlist
;
2476 set_buffer_jbddirty(bh
);
2479 void jbd2_journal_file_buffer(struct journal_head
*jh
,
2480 transaction_t
*transaction
, int jlist
)
2482 jbd_lock_bh_state(jh2bh(jh
));
2483 spin_lock(&transaction
->t_journal
->j_list_lock
);
2484 __jbd2_journal_file_buffer(jh
, transaction
, jlist
);
2485 spin_unlock(&transaction
->t_journal
->j_list_lock
);
2486 jbd_unlock_bh_state(jh2bh(jh
));
2490 * Remove a buffer from its current buffer list in preparation for
2491 * dropping it from its current transaction entirely. If the buffer has
2492 * already started to be used by a subsequent transaction, refile the
2493 * buffer on that transaction's metadata list.
2495 * Called under j_list_lock
2496 * Called under jbd_lock_bh_state(jh2bh(jh))
2498 * jh and bh may be already free when this function returns
2500 void __jbd2_journal_refile_buffer(struct journal_head
*jh
)
2502 int was_dirty
, jlist
;
2503 struct buffer_head
*bh
= jh2bh(jh
);
2505 J_ASSERT_JH(jh
, jbd_is_locked_bh_state(bh
));
2506 if (jh
->b_transaction
)
2507 assert_spin_locked(&jh
->b_transaction
->t_journal
->j_list_lock
);
2509 /* If the buffer is now unused, just drop it. */
2510 if (jh
->b_next_transaction
== NULL
) {
2511 __jbd2_journal_unfile_buffer(jh
);
2516 * It has been modified by a later transaction: add it to the new
2517 * transaction's metadata list.
2520 was_dirty
= test_clear_buffer_jbddirty(bh
);
2521 __jbd2_journal_temp_unlink_buffer(jh
);
2523 * We set b_transaction here because b_next_transaction will inherit
2524 * our jh reference and thus __jbd2_journal_file_buffer() must not
2527 jh
->b_transaction
= jh
->b_next_transaction
;
2528 jh
->b_next_transaction
= NULL
;
2529 if (buffer_freed(bh
))
2531 else if (jh
->b_modified
)
2532 jlist
= BJ_Metadata
;
2534 jlist
= BJ_Reserved
;
2535 __jbd2_journal_file_buffer(jh
, jh
->b_transaction
, jlist
);
2536 J_ASSERT_JH(jh
, jh
->b_transaction
->t_state
== T_RUNNING
);
2539 set_buffer_jbddirty(bh
);
2543 * __jbd2_journal_refile_buffer() with necessary locking added. We take our
2544 * bh reference so that we can safely unlock bh.
2546 * The jh and bh may be freed by this call.
2548 void jbd2_journal_refile_buffer(journal_t
*journal
, struct journal_head
*jh
)
2550 struct buffer_head
*bh
= jh2bh(jh
);
2552 /* Get reference so that buffer cannot be freed before we unlock it */
2554 jbd_lock_bh_state(bh
);
2555 spin_lock(&journal
->j_list_lock
);
2556 __jbd2_journal_refile_buffer(jh
);
2557 jbd_unlock_bh_state(bh
);
2558 spin_unlock(&journal
->j_list_lock
);
2563 * File inode in the inode list of the handle's transaction
2565 static int jbd2_journal_file_inode(handle_t
*handle
, struct jbd2_inode
*jinode
,
2566 unsigned long flags
)
2568 transaction_t
*transaction
= handle
->h_transaction
;
2571 if (is_handle_aborted(handle
))
2573 journal
= transaction
->t_journal
;
2575 jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode
->i_vfs_inode
->i_ino
,
2576 transaction
->t_tid
);
2579 * First check whether inode isn't already on the transaction's
2580 * lists without taking the lock. Note that this check is safe
2581 * without the lock as we cannot race with somebody removing inode
2582 * from the transaction. The reason is that we remove inode from the
2583 * transaction only in journal_release_jbd_inode() and when we commit
2584 * the transaction. We are guarded from the first case by holding
2585 * a reference to the inode. We are safe against the second case
2586 * because if jinode->i_transaction == transaction, commit code
2587 * cannot touch the transaction because we hold reference to it,
2588 * and if jinode->i_next_transaction == transaction, commit code
2589 * will only file the inode where we want it.
2591 if ((jinode
->i_transaction
== transaction
||
2592 jinode
->i_next_transaction
== transaction
) &&
2593 (jinode
->i_flags
& flags
) == flags
)
2596 spin_lock(&journal
->j_list_lock
);
2597 jinode
->i_flags
|= flags
;
2598 /* Is inode already attached where we need it? */
2599 if (jinode
->i_transaction
== transaction
||
2600 jinode
->i_next_transaction
== transaction
)
2604 * We only ever set this variable to 1 so the test is safe. Since
2605 * t_need_data_flush is likely to be set, we do the test to save some
2606 * cacheline bouncing
2608 if (!transaction
->t_need_data_flush
)
2609 transaction
->t_need_data_flush
= 1;
2610 /* On some different transaction's list - should be
2611 * the committing one */
2612 if (jinode
->i_transaction
) {
2613 J_ASSERT(jinode
->i_next_transaction
== NULL
);
2614 J_ASSERT(jinode
->i_transaction
==
2615 journal
->j_committing_transaction
);
2616 jinode
->i_next_transaction
= transaction
;
2619 /* Not on any transaction list... */
2620 J_ASSERT(!jinode
->i_next_transaction
);
2621 jinode
->i_transaction
= transaction
;
2622 list_add(&jinode
->i_list
, &transaction
->t_inode_list
);
2624 spin_unlock(&journal
->j_list_lock
);
2629 int jbd2_journal_inode_add_write(handle_t
*handle
, struct jbd2_inode
*jinode
)
2631 return jbd2_journal_file_inode(handle
, jinode
,
2632 JI_WRITE_DATA
| JI_WAIT_DATA
);
2635 int jbd2_journal_inode_add_wait(handle_t
*handle
, struct jbd2_inode
*jinode
)
2637 return jbd2_journal_file_inode(handle
, jinode
, JI_WAIT_DATA
);
2641 * File truncate and transaction commit interact with each other in a
2642 * non-trivial way. If a transaction writing data block A is
2643 * committing, we cannot discard the data by truncate until we have
2644 * written them. Otherwise if we crashed after the transaction with
2645 * write has committed but before the transaction with truncate has
2646 * committed, we could see stale data in block A. This function is a
2647 * helper to solve this problem. It starts writeout of the truncated
2648 * part in case it is in the committing transaction.
2650 * Filesystem code must call this function when inode is journaled in
2651 * ordered mode before truncation happens and after the inode has been
2652 * placed on orphan list with the new inode size. The second condition
2653 * avoids the race that someone writes new data and we start
2654 * committing the transaction after this function has been called but
2655 * before a transaction for truncate is started (and furthermore it
2656 * allows us to optimize the case where the addition to orphan list
2657 * happens in the same transaction as write --- we don't have to write
2658 * any data in such case).
2660 int jbd2_journal_begin_ordered_truncate(journal_t
*journal
,
2661 struct jbd2_inode
*jinode
,
2664 transaction_t
*inode_trans
, *commit_trans
;
2667 /* This is a quick check to avoid locking if not necessary */
2668 if (!jinode
->i_transaction
)
2670 /* Locks are here just to force reading of recent values, it is
2671 * enough that the transaction was not committing before we started
2672 * a transaction adding the inode to orphan list */
2673 read_lock(&journal
->j_state_lock
);
2674 commit_trans
= journal
->j_committing_transaction
;
2675 read_unlock(&journal
->j_state_lock
);
2676 spin_lock(&journal
->j_list_lock
);
2677 inode_trans
= jinode
->i_transaction
;
2678 spin_unlock(&journal
->j_list_lock
);
2679 if (inode_trans
== commit_trans
) {
2680 ret
= filemap_fdatawrite_range(jinode
->i_vfs_inode
->i_mapping
,
2681 new_size
, LLONG_MAX
);
2683 jbd2_journal_abort(journal
, ret
);