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
) {
46 pr_emerg("JBD2: failed to create transaction cache\n");
52 void jbd2_journal_destroy_transaction_cache(void)
54 kmem_cache_destroy(transaction_cache
);
55 transaction_cache
= NULL
;
58 void jbd2_journal_free_transaction(transaction_t
*transaction
)
60 if (unlikely(ZERO_OR_NULL_PTR(transaction
)))
62 kmem_cache_free(transaction_cache
, transaction
);
66 * Base amount of descriptor blocks we reserve for each transaction.
68 static int jbd2_descriptor_blocks_per_trans(journal_t
*journal
)
70 int tag_space
= journal
->j_blocksize
- sizeof(journal_header_t
);
75 if (jbd2_journal_has_csum_v2or3(journal
))
76 tag_space
-= sizeof(struct jbd2_journal_block_tail
);
77 /* Commit code leaves a slack space of 16 bytes at the end of block */
78 tags_per_block
= (tag_space
- 16) / journal_tag_bytes(journal
);
80 * Revoke descriptors are accounted separately so we need to reserve
81 * space for commit block and normal transaction descriptor blocks.
83 return 1 + DIV_ROUND_UP(journal
->j_max_transaction_buffers
,
88 * jbd2_get_transaction: obtain a new transaction_t object.
90 * Simply initialise a new transaction. Initialize it in
91 * RUNNING state and add it to the current journal (which should not
92 * have an existing running transaction: we only make a new transaction
93 * once we have started to commit the old one).
96 * The journal MUST be locked. We don't perform atomic mallocs on the
97 * new transaction and we can't block without protecting against other
98 * processes trying to touch the journal while it is in transition.
102 static void jbd2_get_transaction(journal_t
*journal
,
103 transaction_t
*transaction
)
105 transaction
->t_journal
= journal
;
106 transaction
->t_state
= T_RUNNING
;
107 transaction
->t_start_time
= ktime_get();
108 transaction
->t_tid
= journal
->j_transaction_sequence
++;
109 transaction
->t_expires
= jiffies
+ journal
->j_commit_interval
;
110 spin_lock_init(&transaction
->t_handle_lock
);
111 atomic_set(&transaction
->t_updates
, 0);
112 atomic_set(&transaction
->t_outstanding_credits
,
113 jbd2_descriptor_blocks_per_trans(journal
) +
114 atomic_read(&journal
->j_reserved_credits
));
115 atomic_set(&transaction
->t_outstanding_revokes
, 0);
116 atomic_set(&transaction
->t_handle_count
, 0);
117 INIT_LIST_HEAD(&transaction
->t_inode_list
);
118 INIT_LIST_HEAD(&transaction
->t_private_list
);
120 /* Set up the commit timer for the new transaction. */
121 journal
->j_commit_timer
.expires
= round_jiffies_up(transaction
->t_expires
);
122 add_timer(&journal
->j_commit_timer
);
124 J_ASSERT(journal
->j_running_transaction
== NULL
);
125 journal
->j_running_transaction
= transaction
;
126 transaction
->t_max_wait
= 0;
127 transaction
->t_start
= jiffies
;
128 transaction
->t_requested
= 0;
134 * A handle_t is an object which represents a single atomic update to a
135 * filesystem, and which tracks all of the modifications which form part
136 * of that one update.
140 * Update transaction's maximum wait time, if debugging is enabled.
142 * In order for t_max_wait to be reliable, it must be protected by a
143 * lock. But doing so will mean that start_this_handle() can not be
144 * run in parallel on SMP systems, which limits our scalability. So
145 * unless debugging is enabled, we no longer update t_max_wait, which
146 * means that maximum wait time reported by the jbd2_run_stats
147 * tracepoint will always be zero.
149 static inline void update_t_max_wait(transaction_t
*transaction
,
152 #ifdef CONFIG_JBD2_DEBUG
153 if (jbd2_journal_enable_debug
&&
154 time_after(transaction
->t_start
, ts
)) {
155 ts
= jbd2_time_diff(ts
, transaction
->t_start
);
156 spin_lock(&transaction
->t_handle_lock
);
157 if (ts
> transaction
->t_max_wait
)
158 transaction
->t_max_wait
= ts
;
159 spin_unlock(&transaction
->t_handle_lock
);
165 * Wait until running transaction passes to T_FLUSH state and new transaction
166 * can thus be started. Also starts the commit if needed. The function expects
167 * running transaction to exist and releases j_state_lock.
169 static void wait_transaction_locked(journal_t
*journal
)
170 __releases(journal
->j_state_lock
)
174 tid_t tid
= journal
->j_running_transaction
->t_tid
;
176 prepare_to_wait(&journal
->j_wait_transaction_locked
, &wait
,
177 TASK_UNINTERRUPTIBLE
);
178 need_to_start
= !tid_geq(journal
->j_commit_request
, tid
);
179 read_unlock(&journal
->j_state_lock
);
181 jbd2_log_start_commit(journal
, tid
);
182 jbd2_might_wait_for_commit(journal
);
184 finish_wait(&journal
->j_wait_transaction_locked
, &wait
);
188 * Wait until running transaction transitions from T_SWITCH to T_FLUSH
189 * state and new transaction can thus be started. The function releases
192 static void wait_transaction_switching(journal_t
*journal
)
193 __releases(journal
->j_state_lock
)
197 if (WARN_ON(!journal
->j_running_transaction
||
198 journal
->j_running_transaction
->t_state
!= T_SWITCH
)) {
199 read_unlock(&journal
->j_state_lock
);
202 prepare_to_wait(&journal
->j_wait_transaction_locked
, &wait
,
203 TASK_UNINTERRUPTIBLE
);
204 read_unlock(&journal
->j_state_lock
);
206 * We don't call jbd2_might_wait_for_commit() here as there's no
207 * waiting for outstanding handles happening anymore in T_SWITCH state
208 * and handling of reserved handles actually relies on that for
212 finish_wait(&journal
->j_wait_transaction_locked
, &wait
);
215 static void sub_reserved_credits(journal_t
*journal
, int blocks
)
217 atomic_sub(blocks
, &journal
->j_reserved_credits
);
218 wake_up(&journal
->j_wait_reserved
);
222 * Wait until we can add credits for handle to the running transaction. Called
223 * with j_state_lock held for reading. Returns 0 if handle joined the running
224 * transaction. Returns 1 if we had to wait, j_state_lock is dropped, and
227 * Note: because j_state_lock may be dropped depending on the return
228 * value, we need to fake out sparse so ti doesn't complain about a
229 * locking imbalance. Callers of add_transaction_credits will need to
230 * make a similar accomodation.
232 static int add_transaction_credits(journal_t
*journal
, int blocks
,
234 __must_hold(&journal
->j_state_lock
)
236 transaction_t
*t
= journal
->j_running_transaction
;
238 int total
= blocks
+ rsv_blocks
;
241 * If the current transaction is locked down for commit, wait
242 * for the lock to be released.
244 if (t
->t_state
!= T_RUNNING
) {
245 WARN_ON_ONCE(t
->t_state
>= T_FLUSH
);
246 wait_transaction_locked(journal
);
247 __acquire(&journal
->j_state_lock
); /* fake out sparse */
252 * If there is not enough space left in the log to write all
253 * potential buffers requested by this operation, we need to
254 * stall pending a log checkpoint to free some more log space.
256 needed
= atomic_add_return(total
, &t
->t_outstanding_credits
);
257 if (needed
> journal
->j_max_transaction_buffers
) {
259 * If the current transaction is already too large,
260 * then start to commit it: we can then go back and
261 * attach this handle to a new transaction.
263 atomic_sub(total
, &t
->t_outstanding_credits
);
266 * Is the number of reserved credits in the current transaction too
267 * big to fit this handle? Wait until reserved credits are freed.
269 if (atomic_read(&journal
->j_reserved_credits
) + total
>
270 journal
->j_max_transaction_buffers
) {
271 read_unlock(&journal
->j_state_lock
);
272 jbd2_might_wait_for_commit(journal
);
273 wait_event(journal
->j_wait_reserved
,
274 atomic_read(&journal
->j_reserved_credits
) + total
<=
275 journal
->j_max_transaction_buffers
);
276 __acquire(&journal
->j_state_lock
); /* fake out sparse */
280 wait_transaction_locked(journal
);
281 __acquire(&journal
->j_state_lock
); /* fake out sparse */
286 * The commit code assumes that it can get enough log space
287 * without forcing a checkpoint. This is *critical* for
288 * correctness: a checkpoint of a buffer which is also
289 * associated with a committing transaction creates a deadlock,
290 * so commit simply cannot force through checkpoints.
292 * We must therefore ensure the necessary space in the journal
293 * *before* starting to dirty potentially checkpointed buffers
294 * in the new transaction.
296 if (jbd2_log_space_left(journal
) < journal
->j_max_transaction_buffers
) {
297 atomic_sub(total
, &t
->t_outstanding_credits
);
298 read_unlock(&journal
->j_state_lock
);
299 jbd2_might_wait_for_commit(journal
);
300 write_lock(&journal
->j_state_lock
);
301 if (jbd2_log_space_left(journal
) <
302 journal
->j_max_transaction_buffers
)
303 __jbd2_log_wait_for_space(journal
);
304 write_unlock(&journal
->j_state_lock
);
305 __acquire(&journal
->j_state_lock
); /* fake out sparse */
309 /* No reservation? We are done... */
313 needed
= atomic_add_return(rsv_blocks
, &journal
->j_reserved_credits
);
314 /* We allow at most half of a transaction to be reserved */
315 if (needed
> journal
->j_max_transaction_buffers
/ 2) {
316 sub_reserved_credits(journal
, rsv_blocks
);
317 atomic_sub(total
, &t
->t_outstanding_credits
);
318 read_unlock(&journal
->j_state_lock
);
319 jbd2_might_wait_for_commit(journal
);
320 wait_event(journal
->j_wait_reserved
,
321 atomic_read(&journal
->j_reserved_credits
) + rsv_blocks
322 <= journal
->j_max_transaction_buffers
/ 2);
323 __acquire(&journal
->j_state_lock
); /* fake out sparse */
330 * start_this_handle: Given a handle, deal with any locking or stalling
331 * needed to make sure that there is enough journal space for the handle
332 * to begin. Attach the handle to a transaction and set up the
333 * transaction's buffer credits.
336 static int start_this_handle(journal_t
*journal
, handle_t
*handle
,
339 transaction_t
*transaction
, *new_transaction
= NULL
;
340 int blocks
= handle
->h_total_credits
;
342 unsigned long ts
= jiffies
;
344 if (handle
->h_rsv_handle
)
345 rsv_blocks
= handle
->h_rsv_handle
->h_total_credits
;
348 * Limit the number of reserved credits to 1/2 of maximum transaction
349 * size and limit the number of total credits to not exceed maximum
350 * transaction size per operation.
352 if ((rsv_blocks
> journal
->j_max_transaction_buffers
/ 2) ||
353 (rsv_blocks
+ blocks
> journal
->j_max_transaction_buffers
)) {
354 printk(KERN_ERR
"JBD2: %s wants too many credits "
355 "credits:%d rsv_credits:%d max:%d\n",
356 current
->comm
, blocks
, rsv_blocks
,
357 journal
->j_max_transaction_buffers
);
364 * This check is racy but it is just an optimization of allocating new
365 * transaction early if there are high chances we'll need it. If we
366 * guess wrong, we'll retry or free unused transaction.
368 if (!data_race(journal
->j_running_transaction
)) {
370 * If __GFP_FS is not present, then we may be being called from
371 * inside the fs writeback layer, so we MUST NOT fail.
373 if ((gfp_mask
& __GFP_FS
) == 0)
374 gfp_mask
|= __GFP_NOFAIL
;
375 new_transaction
= kmem_cache_zalloc(transaction_cache
,
377 if (!new_transaction
)
381 jbd_debug(3, "New handle %p going live.\n", handle
);
384 * We need to hold j_state_lock until t_updates has been incremented,
385 * for proper journal barrier handling
388 read_lock(&journal
->j_state_lock
);
389 BUG_ON(journal
->j_flags
& JBD2_UNMOUNT
);
390 if (is_journal_aborted(journal
) ||
391 (journal
->j_errno
!= 0 && !(journal
->j_flags
& JBD2_ACK_ERR
))) {
392 read_unlock(&journal
->j_state_lock
);
393 jbd2_journal_free_transaction(new_transaction
);
398 * Wait on the journal's transaction barrier if necessary. Specifically
399 * we allow reserved handles to proceed because otherwise commit could
400 * deadlock on page writeback not being able to complete.
402 if (!handle
->h_reserved
&& journal
->j_barrier_count
) {
403 read_unlock(&journal
->j_state_lock
);
404 wait_event(journal
->j_wait_transaction_locked
,
405 journal
->j_barrier_count
== 0);
409 if (!journal
->j_running_transaction
) {
410 read_unlock(&journal
->j_state_lock
);
411 if (!new_transaction
)
412 goto alloc_transaction
;
413 write_lock(&journal
->j_state_lock
);
414 if (!journal
->j_running_transaction
&&
415 (handle
->h_reserved
|| !journal
->j_barrier_count
)) {
416 jbd2_get_transaction(journal
, new_transaction
);
417 new_transaction
= NULL
;
419 write_unlock(&journal
->j_state_lock
);
423 transaction
= journal
->j_running_transaction
;
425 if (!handle
->h_reserved
) {
426 /* We may have dropped j_state_lock - restart in that case */
427 if (add_transaction_credits(journal
, blocks
, rsv_blocks
)) {
429 * add_transaction_credits releases
430 * j_state_lock on a non-zero return
432 __release(&journal
->j_state_lock
);
437 * We have handle reserved so we are allowed to join T_LOCKED
438 * transaction and we don't have to check for transaction size
439 * and journal space. But we still have to wait while running
440 * transaction is being switched to a committing one as it
441 * won't wait for any handles anymore.
443 if (transaction
->t_state
== T_SWITCH
) {
444 wait_transaction_switching(journal
);
447 sub_reserved_credits(journal
, blocks
);
448 handle
->h_reserved
= 0;
451 /* OK, account for the buffers that this operation expects to
452 * use and add the handle to the running transaction.
454 update_t_max_wait(transaction
, ts
);
455 handle
->h_transaction
= transaction
;
456 handle
->h_requested_credits
= blocks
;
457 handle
->h_revoke_credits_requested
= handle
->h_revoke_credits
;
458 handle
->h_start_jiffies
= jiffies
;
459 atomic_inc(&transaction
->t_updates
);
460 atomic_inc(&transaction
->t_handle_count
);
461 jbd_debug(4, "Handle %p given %d credits (total %d, free %lu)\n",
463 atomic_read(&transaction
->t_outstanding_credits
),
464 jbd2_log_space_left(journal
));
465 read_unlock(&journal
->j_state_lock
);
466 current
->journal_info
= handle
;
468 rwsem_acquire_read(&journal
->j_trans_commit_map
, 0, 0, _THIS_IP_
);
469 jbd2_journal_free_transaction(new_transaction
);
471 * Ensure that no allocations done while the transaction is open are
472 * going to recurse back to the fs layer.
474 handle
->saved_alloc_context
= memalloc_nofs_save();
478 /* Allocate a new handle. This should probably be in a slab... */
479 static handle_t
*new_handle(int nblocks
)
481 handle_t
*handle
= jbd2_alloc_handle(GFP_NOFS
);
484 handle
->h_total_credits
= nblocks
;
490 handle_t
*jbd2__journal_start(journal_t
*journal
, int nblocks
, int rsv_blocks
,
491 int revoke_records
, gfp_t gfp_mask
,
492 unsigned int type
, unsigned int line_no
)
494 handle_t
*handle
= journal_current_handle();
498 return ERR_PTR(-EROFS
);
501 J_ASSERT(handle
->h_transaction
->t_journal
== journal
);
506 nblocks
+= DIV_ROUND_UP(revoke_records
,
507 journal
->j_revoke_records_per_block
);
508 handle
= new_handle(nblocks
);
510 return ERR_PTR(-ENOMEM
);
512 handle_t
*rsv_handle
;
514 rsv_handle
= new_handle(rsv_blocks
);
516 jbd2_free_handle(handle
);
517 return ERR_PTR(-ENOMEM
);
519 rsv_handle
->h_reserved
= 1;
520 rsv_handle
->h_journal
= journal
;
521 handle
->h_rsv_handle
= rsv_handle
;
523 handle
->h_revoke_credits
= revoke_records
;
525 err
= start_this_handle(journal
, handle
, gfp_mask
);
527 if (handle
->h_rsv_handle
)
528 jbd2_free_handle(handle
->h_rsv_handle
);
529 jbd2_free_handle(handle
);
532 handle
->h_type
= type
;
533 handle
->h_line_no
= line_no
;
534 trace_jbd2_handle_start(journal
->j_fs_dev
->bd_dev
,
535 handle
->h_transaction
->t_tid
, type
,
540 EXPORT_SYMBOL(jbd2__journal_start
);
544 * jbd2_journal_start() - Obtain a new handle.
545 * @journal: Journal to start transaction on.
546 * @nblocks: number of block buffer we might modify
548 * We make sure that the transaction can guarantee at least nblocks of
549 * modified buffers in the log. We block until the log can guarantee
550 * that much space. Additionally, if rsv_blocks > 0, we also create another
551 * handle with rsv_blocks reserved blocks in the journal. This handle is
552 * stored in h_rsv_handle. It is not attached to any particular transaction
553 * and thus doesn't block transaction commit. If the caller uses this reserved
554 * handle, it has to set h_rsv_handle to NULL as otherwise jbd2_journal_stop()
555 * on the parent handle will dispose the reserved one. Reserved handle has to
556 * be converted to a normal handle using jbd2_journal_start_reserved() before
559 * Return a pointer to a newly allocated handle, or an ERR_PTR() value
562 handle_t
*jbd2_journal_start(journal_t
*journal
, int nblocks
)
564 return jbd2__journal_start(journal
, nblocks
, 0, 0, GFP_NOFS
, 0, 0);
566 EXPORT_SYMBOL(jbd2_journal_start
);
568 static void __jbd2_journal_unreserve_handle(handle_t
*handle
, transaction_t
*t
)
570 journal_t
*journal
= handle
->h_journal
;
572 WARN_ON(!handle
->h_reserved
);
573 sub_reserved_credits(journal
, handle
->h_total_credits
);
575 atomic_sub(handle
->h_total_credits
, &t
->t_outstanding_credits
);
578 void jbd2_journal_free_reserved(handle_t
*handle
)
580 journal_t
*journal
= handle
->h_journal
;
582 /* Get j_state_lock to pin running transaction if it exists */
583 read_lock(&journal
->j_state_lock
);
584 __jbd2_journal_unreserve_handle(handle
, journal
->j_running_transaction
);
585 read_unlock(&journal
->j_state_lock
);
586 jbd2_free_handle(handle
);
588 EXPORT_SYMBOL(jbd2_journal_free_reserved
);
591 * jbd2_journal_start_reserved() - start reserved handle
592 * @handle: handle to start
593 * @type: for handle statistics
594 * @line_no: for handle statistics
596 * Start handle that has been previously reserved with jbd2_journal_reserve().
597 * This attaches @handle to the running transaction (or creates one if there's
598 * not transaction running). Unlike jbd2_journal_start() this function cannot
599 * block on journal commit, checkpointing, or similar stuff. It can block on
600 * memory allocation or frozen journal though.
602 * Return 0 on success, non-zero on error - handle is freed in that case.
604 int jbd2_journal_start_reserved(handle_t
*handle
, unsigned int type
,
605 unsigned int line_no
)
607 journal_t
*journal
= handle
->h_journal
;
610 if (WARN_ON(!handle
->h_reserved
)) {
611 /* Someone passed in normal handle? Just stop it. */
612 jbd2_journal_stop(handle
);
616 * Usefulness of mixing of reserved and unreserved handles is
617 * questionable. So far nobody seems to need it so just error out.
619 if (WARN_ON(current
->journal_info
)) {
620 jbd2_journal_free_reserved(handle
);
624 handle
->h_journal
= NULL
;
626 * GFP_NOFS is here because callers are likely from writeback or
627 * similarly constrained call sites
629 ret
= start_this_handle(journal
, handle
, GFP_NOFS
);
631 handle
->h_journal
= journal
;
632 jbd2_journal_free_reserved(handle
);
635 handle
->h_type
= type
;
636 handle
->h_line_no
= line_no
;
637 trace_jbd2_handle_start(journal
->j_fs_dev
->bd_dev
,
638 handle
->h_transaction
->t_tid
, type
,
639 line_no
, handle
->h_total_credits
);
642 EXPORT_SYMBOL(jbd2_journal_start_reserved
);
645 * jbd2_journal_extend() - extend buffer credits.
646 * @handle: handle to 'extend'
647 * @nblocks: nr blocks to try to extend by.
648 * @revoke_records: number of revoke records to try to extend by.
650 * Some transactions, such as large extends and truncates, can be done
651 * atomically all at once or in several stages. The operation requests
652 * a credit for a number of buffer modifications in advance, but can
653 * extend its credit if it needs more.
655 * jbd2_journal_extend tries to give the running handle more buffer credits.
656 * It does not guarantee that allocation - this is a best-effort only.
657 * The calling process MUST be able to deal cleanly with a failure to
660 * Return 0 on success, non-zero on failure.
662 * return code < 0 implies an error
663 * return code > 0 implies normal transaction-full status.
665 int jbd2_journal_extend(handle_t
*handle
, int nblocks
, int revoke_records
)
667 transaction_t
*transaction
= handle
->h_transaction
;
672 if (is_handle_aborted(handle
))
674 journal
= transaction
->t_journal
;
678 read_lock(&journal
->j_state_lock
);
680 /* Don't extend a locked-down transaction! */
681 if (transaction
->t_state
!= T_RUNNING
) {
682 jbd_debug(3, "denied handle %p %d blocks: "
683 "transaction not running\n", handle
, nblocks
);
687 nblocks
+= DIV_ROUND_UP(
688 handle
->h_revoke_credits_requested
+ revoke_records
,
689 journal
->j_revoke_records_per_block
) -
691 handle
->h_revoke_credits_requested
,
692 journal
->j_revoke_records_per_block
);
693 spin_lock(&transaction
->t_handle_lock
);
694 wanted
= atomic_add_return(nblocks
,
695 &transaction
->t_outstanding_credits
);
697 if (wanted
> journal
->j_max_transaction_buffers
) {
698 jbd_debug(3, "denied handle %p %d blocks: "
699 "transaction too large\n", handle
, nblocks
);
700 atomic_sub(nblocks
, &transaction
->t_outstanding_credits
);
704 trace_jbd2_handle_extend(journal
->j_fs_dev
->bd_dev
,
706 handle
->h_type
, handle
->h_line_no
,
707 handle
->h_total_credits
,
710 handle
->h_total_credits
+= nblocks
;
711 handle
->h_requested_credits
+= nblocks
;
712 handle
->h_revoke_credits
+= revoke_records
;
713 handle
->h_revoke_credits_requested
+= revoke_records
;
716 jbd_debug(3, "extended handle %p by %d\n", handle
, nblocks
);
718 spin_unlock(&transaction
->t_handle_lock
);
720 read_unlock(&journal
->j_state_lock
);
724 static void stop_this_handle(handle_t
*handle
)
726 transaction_t
*transaction
= handle
->h_transaction
;
727 journal_t
*journal
= transaction
->t_journal
;
730 J_ASSERT(journal_current_handle() == handle
);
731 J_ASSERT(atomic_read(&transaction
->t_updates
) > 0);
732 current
->journal_info
= NULL
;
734 * Subtract necessary revoke descriptor blocks from handle credits. We
735 * take care to account only for revoke descriptor blocks the
736 * transaction will really need as large sequences of transactions with
737 * small numbers of revokes are relatively common.
739 revokes
= handle
->h_revoke_credits_requested
- handle
->h_revoke_credits
;
741 int t_revokes
, revoke_descriptors
;
742 int rr_per_blk
= journal
->j_revoke_records_per_block
;
744 WARN_ON_ONCE(DIV_ROUND_UP(revokes
, rr_per_blk
)
745 > handle
->h_total_credits
);
746 t_revokes
= atomic_add_return(revokes
,
747 &transaction
->t_outstanding_revokes
);
749 DIV_ROUND_UP(t_revokes
, rr_per_blk
) -
750 DIV_ROUND_UP(t_revokes
- revokes
, rr_per_blk
);
751 handle
->h_total_credits
-= revoke_descriptors
;
753 atomic_sub(handle
->h_total_credits
,
754 &transaction
->t_outstanding_credits
);
755 if (handle
->h_rsv_handle
)
756 __jbd2_journal_unreserve_handle(handle
->h_rsv_handle
,
758 if (atomic_dec_and_test(&transaction
->t_updates
))
759 wake_up(&journal
->j_wait_updates
);
761 rwsem_release(&journal
->j_trans_commit_map
, _THIS_IP_
);
763 * Scope of the GFP_NOFS context is over here and so we can restore the
764 * original alloc context.
766 memalloc_nofs_restore(handle
->saved_alloc_context
);
770 * jbd2__journal_restart() - restart a handle .
771 * @handle: handle to restart
772 * @nblocks: nr credits requested
773 * @revoke_records: number of revoke record credits requested
774 * @gfp_mask: memory allocation flags (for start_this_handle)
776 * Restart a handle for a multi-transaction filesystem
779 * If the jbd2_journal_extend() call above fails to grant new buffer credits
780 * to a running handle, a call to jbd2_journal_restart will commit the
781 * handle's transaction so far and reattach the handle to a new
782 * transaction capable of guaranteeing the requested number of
783 * credits. We preserve reserved handle if there's any attached to the
786 int jbd2__journal_restart(handle_t
*handle
, int nblocks
, int revoke_records
,
789 transaction_t
*transaction
= handle
->h_transaction
;
795 /* If we've had an abort of any type, don't even think about
796 * actually doing the restart! */
797 if (is_handle_aborted(handle
))
799 journal
= transaction
->t_journal
;
800 tid
= transaction
->t_tid
;
803 * First unlink the handle from its current transaction, and start the
806 jbd_debug(2, "restarting handle %p\n", handle
);
807 stop_this_handle(handle
);
808 handle
->h_transaction
= NULL
;
811 * TODO: If we use READ_ONCE / WRITE_ONCE for j_commit_request we can
812 * get rid of pointless j_state_lock traffic like this.
814 read_lock(&journal
->j_state_lock
);
815 need_to_start
= !tid_geq(journal
->j_commit_request
, tid
);
816 read_unlock(&journal
->j_state_lock
);
818 jbd2_log_start_commit(journal
, tid
);
819 handle
->h_total_credits
= nblocks
+
820 DIV_ROUND_UP(revoke_records
,
821 journal
->j_revoke_records_per_block
);
822 handle
->h_revoke_credits
= revoke_records
;
823 ret
= start_this_handle(journal
, handle
, gfp_mask
);
824 trace_jbd2_handle_restart(journal
->j_fs_dev
->bd_dev
,
825 ret
? 0 : handle
->h_transaction
->t_tid
,
826 handle
->h_type
, handle
->h_line_no
,
827 handle
->h_total_credits
);
830 EXPORT_SYMBOL(jbd2__journal_restart
);
833 int jbd2_journal_restart(handle_t
*handle
, int nblocks
)
835 return jbd2__journal_restart(handle
, nblocks
, 0, GFP_NOFS
);
837 EXPORT_SYMBOL(jbd2_journal_restart
);
840 * jbd2_journal_lock_updates () - establish a transaction barrier.
841 * @journal: Journal to establish a barrier on.
843 * This locks out any further updates from being started, and blocks
844 * until all existing updates have completed, returning only once the
845 * journal is in a quiescent state with no updates running.
847 * The journal lock should not be held on entry.
849 void jbd2_journal_lock_updates(journal_t
*journal
)
853 jbd2_might_wait_for_commit(journal
);
855 write_lock(&journal
->j_state_lock
);
856 ++journal
->j_barrier_count
;
858 /* Wait until there are no reserved handles */
859 if (atomic_read(&journal
->j_reserved_credits
)) {
860 write_unlock(&journal
->j_state_lock
);
861 wait_event(journal
->j_wait_reserved
,
862 atomic_read(&journal
->j_reserved_credits
) == 0);
863 write_lock(&journal
->j_state_lock
);
866 /* Wait until there are no running updates */
868 transaction_t
*transaction
= journal
->j_running_transaction
;
873 spin_lock(&transaction
->t_handle_lock
);
874 prepare_to_wait(&journal
->j_wait_updates
, &wait
,
875 TASK_UNINTERRUPTIBLE
);
876 if (!atomic_read(&transaction
->t_updates
)) {
877 spin_unlock(&transaction
->t_handle_lock
);
878 finish_wait(&journal
->j_wait_updates
, &wait
);
881 spin_unlock(&transaction
->t_handle_lock
);
882 write_unlock(&journal
->j_state_lock
);
884 finish_wait(&journal
->j_wait_updates
, &wait
);
885 write_lock(&journal
->j_state_lock
);
887 write_unlock(&journal
->j_state_lock
);
890 * We have now established a barrier against other normal updates, but
891 * we also need to barrier against other jbd2_journal_lock_updates() calls
892 * to make sure that we serialise special journal-locked operations
895 mutex_lock(&journal
->j_barrier
);
899 * jbd2_journal_unlock_updates () - release barrier
900 * @journal: Journal to release the barrier on.
902 * Release a transaction barrier obtained with jbd2_journal_lock_updates().
904 * Should be called without the journal lock held.
906 void jbd2_journal_unlock_updates (journal_t
*journal
)
908 J_ASSERT(journal
->j_barrier_count
!= 0);
910 mutex_unlock(&journal
->j_barrier
);
911 write_lock(&journal
->j_state_lock
);
912 --journal
->j_barrier_count
;
913 write_unlock(&journal
->j_state_lock
);
914 wake_up(&journal
->j_wait_transaction_locked
);
917 static void warn_dirty_buffer(struct buffer_head
*bh
)
920 "JBD2: Spotted dirty metadata buffer (dev = %pg, blocknr = %llu). "
921 "There's a risk of filesystem corruption in case of system "
923 bh
->b_bdev
, (unsigned long long)bh
->b_blocknr
);
926 /* Call t_frozen trigger and copy buffer data into jh->b_frozen_data. */
927 static void jbd2_freeze_jh_data(struct journal_head
*jh
)
932 struct buffer_head
*bh
= jh2bh(jh
);
934 J_EXPECT_JH(jh
, buffer_uptodate(bh
), "Possible IO failure.\n");
936 offset
= offset_in_page(bh
->b_data
);
937 source
= kmap_atomic(page
);
938 /* Fire data frozen trigger just before we copy the data */
939 jbd2_buffer_frozen_trigger(jh
, source
+ offset
, jh
->b_triggers
);
940 memcpy(jh
->b_frozen_data
, source
+ offset
, bh
->b_size
);
941 kunmap_atomic(source
);
944 * Now that the frozen data is saved off, we need to store any matching
947 jh
->b_frozen_triggers
= jh
->b_triggers
;
951 * If the buffer is already part of the current transaction, then there
952 * is nothing we need to do. If it is already part of a prior
953 * transaction which we are still committing to disk, then we need to
954 * make sure that we do not overwrite the old copy: we do copy-out to
955 * preserve the copy going to disk. We also account the buffer against
956 * the handle's metadata buffer credits (unless the buffer is already
957 * part of the transaction, that is).
961 do_get_write_access(handle_t
*handle
, struct journal_head
*jh
,
964 struct buffer_head
*bh
;
965 transaction_t
*transaction
= handle
->h_transaction
;
968 char *frozen_buffer
= NULL
;
969 unsigned long start_lock
, time_lock
;
971 journal
= transaction
->t_journal
;
973 jbd_debug(5, "journal_head %p, force_copy %d\n", jh
, force_copy
);
975 JBUFFER_TRACE(jh
, "entry");
979 /* @@@ Need to check for errors here at some point. */
981 start_lock
= jiffies
;
983 spin_lock(&jh
->b_state_lock
);
985 /* If it takes too long to lock the buffer, trace it */
986 time_lock
= jbd2_time_diff(start_lock
, jiffies
);
987 if (time_lock
> HZ
/10)
988 trace_jbd2_lock_buffer_stall(bh
->b_bdev
->bd_dev
,
989 jiffies_to_msecs(time_lock
));
991 /* We now hold the buffer lock so it is safe to query the buffer
992 * state. Is the buffer dirty?
994 * If so, there are two possibilities. The buffer may be
995 * non-journaled, and undergoing a quite legitimate writeback.
996 * Otherwise, it is journaled, and we don't expect dirty buffers
997 * in that state (the buffers should be marked JBD_Dirty
998 * instead.) So either the IO is being done under our own
999 * control and this is a bug, or it's a third party IO such as
1000 * dump(8) (which may leave the buffer scheduled for read ---
1001 * ie. locked but not dirty) or tune2fs (which may actually have
1002 * the buffer dirtied, ugh.) */
1004 if (buffer_dirty(bh
)) {
1006 * First question: is this buffer already part of the current
1007 * transaction or the existing committing transaction?
1009 if (jh
->b_transaction
) {
1011 jh
->b_transaction
== transaction
||
1012 jh
->b_transaction
==
1013 journal
->j_committing_transaction
);
1014 if (jh
->b_next_transaction
)
1015 J_ASSERT_JH(jh
, jh
->b_next_transaction
==
1017 warn_dirty_buffer(bh
);
1020 * In any case we need to clean the dirty flag and we must
1021 * do it under the buffer lock to be sure we don't race
1022 * with running write-out.
1024 JBUFFER_TRACE(jh
, "Journalling dirty buffer");
1025 clear_buffer_dirty(bh
);
1026 set_buffer_jbddirty(bh
);
1032 if (is_handle_aborted(handle
)) {
1033 spin_unlock(&jh
->b_state_lock
);
1039 * The buffer is already part of this transaction if b_transaction or
1040 * b_next_transaction points to it
1042 if (jh
->b_transaction
== transaction
||
1043 jh
->b_next_transaction
== transaction
)
1047 * this is the first time this transaction is touching this buffer,
1048 * reset the modified flag
1053 * If the buffer is not journaled right now, we need to make sure it
1054 * doesn't get written to disk before the caller actually commits the
1057 if (!jh
->b_transaction
) {
1058 JBUFFER_TRACE(jh
, "no transaction");
1059 J_ASSERT_JH(jh
, !jh
->b_next_transaction
);
1060 JBUFFER_TRACE(jh
, "file as BJ_Reserved");
1062 * Make sure all stores to jh (b_modified, b_frozen_data) are
1063 * visible before attaching it to the running transaction.
1064 * Paired with barrier in jbd2_write_access_granted()
1067 spin_lock(&journal
->j_list_lock
);
1068 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Reserved
);
1069 spin_unlock(&journal
->j_list_lock
);
1073 * If there is already a copy-out version of this buffer, then we don't
1074 * need to make another one
1076 if (jh
->b_frozen_data
) {
1077 JBUFFER_TRACE(jh
, "has frozen data");
1078 J_ASSERT_JH(jh
, jh
->b_next_transaction
== NULL
);
1082 JBUFFER_TRACE(jh
, "owned by older transaction");
1083 J_ASSERT_JH(jh
, jh
->b_next_transaction
== NULL
);
1084 J_ASSERT_JH(jh
, jh
->b_transaction
== journal
->j_committing_transaction
);
1087 * There is one case we have to be very careful about. If the
1088 * committing transaction is currently writing this buffer out to disk
1089 * and has NOT made a copy-out, then we cannot modify the buffer
1090 * contents at all right now. The essence of copy-out is that it is
1091 * the extra copy, not the primary copy, which gets journaled. If the
1092 * primary copy is already going to disk then we cannot do copy-out
1095 if (buffer_shadow(bh
)) {
1096 JBUFFER_TRACE(jh
, "on shadow: sleep");
1097 spin_unlock(&jh
->b_state_lock
);
1098 wait_on_bit_io(&bh
->b_state
, BH_Shadow
, TASK_UNINTERRUPTIBLE
);
1103 * Only do the copy if the currently-owning transaction still needs it.
1104 * If buffer isn't on BJ_Metadata list, the committing transaction is
1105 * past that stage (here we use the fact that BH_Shadow is set under
1106 * bh_state lock together with refiling to BJ_Shadow list and at this
1107 * point we know the buffer doesn't have BH_Shadow set).
1109 * Subtle point, though: if this is a get_undo_access, then we will be
1110 * relying on the frozen_data to contain the new value of the
1111 * committed_data record after the transaction, so we HAVE to force the
1112 * frozen_data copy in that case.
1114 if (jh
->b_jlist
== BJ_Metadata
|| force_copy
) {
1115 JBUFFER_TRACE(jh
, "generate frozen data");
1116 if (!frozen_buffer
) {
1117 JBUFFER_TRACE(jh
, "allocate memory for buffer");
1118 spin_unlock(&jh
->b_state_lock
);
1119 frozen_buffer
= jbd2_alloc(jh2bh(jh
)->b_size
,
1120 GFP_NOFS
| __GFP_NOFAIL
);
1123 jh
->b_frozen_data
= frozen_buffer
;
1124 frozen_buffer
= NULL
;
1125 jbd2_freeze_jh_data(jh
);
1129 * Make sure all stores to jh (b_modified, b_frozen_data) are visible
1130 * before attaching it to the running transaction. Paired with barrier
1131 * in jbd2_write_access_granted()
1134 jh
->b_next_transaction
= transaction
;
1137 spin_unlock(&jh
->b_state_lock
);
1140 * If we are about to journal a buffer, then any revoke pending on it is
1143 jbd2_journal_cancel_revoke(handle
, jh
);
1146 if (unlikely(frozen_buffer
)) /* It's usually NULL */
1147 jbd2_free(frozen_buffer
, bh
->b_size
);
1149 JBUFFER_TRACE(jh
, "exit");
1153 /* Fast check whether buffer is already attached to the required transaction */
1154 static bool jbd2_write_access_granted(handle_t
*handle
, struct buffer_head
*bh
,
1157 struct journal_head
*jh
;
1160 /* Dirty buffers require special handling... */
1161 if (buffer_dirty(bh
))
1165 * RCU protects us from dereferencing freed pages. So the checks we do
1166 * are guaranteed not to oops. However the jh slab object can get freed
1167 * & reallocated while we work with it. So we have to be careful. When
1168 * we see jh attached to the running transaction, we know it must stay
1169 * so until the transaction is committed. Thus jh won't be freed and
1170 * will be attached to the same bh while we run. However it can
1171 * happen jh gets freed, reallocated, and attached to the transaction
1172 * just after we get pointer to it from bh. So we have to be careful
1173 * and recheck jh still belongs to our bh before we return success.
1176 if (!buffer_jbd(bh
))
1178 /* This should be bh2jh() but that doesn't work with inline functions */
1179 jh
= READ_ONCE(bh
->b_private
);
1182 /* For undo access buffer must have data copied */
1183 if (undo
&& !jh
->b_committed_data
)
1185 if (READ_ONCE(jh
->b_transaction
) != handle
->h_transaction
&&
1186 READ_ONCE(jh
->b_next_transaction
) != handle
->h_transaction
)
1189 * There are two reasons for the barrier here:
1190 * 1) Make sure to fetch b_bh after we did previous checks so that we
1191 * detect when jh went through free, realloc, attach to transaction
1192 * while we were checking. Paired with implicit barrier in that path.
1193 * 2) So that access to bh done after jbd2_write_access_granted()
1194 * doesn't get reordered and see inconsistent state of concurrent
1195 * do_get_write_access().
1198 if (unlikely(jh
->b_bh
!= bh
))
1207 * jbd2_journal_get_write_access() - notify intent to modify a buffer
1208 * for metadata (not data) update.
1209 * @handle: transaction to add buffer modifications to
1210 * @bh: bh to be used for metadata writes
1212 * Returns: error code or 0 on success.
1214 * In full data journalling mode the buffer may be of type BJ_AsyncData,
1215 * because we're ``write()ing`` a buffer which is also part of a shared mapping.
1218 int jbd2_journal_get_write_access(handle_t
*handle
, struct buffer_head
*bh
)
1220 struct journal_head
*jh
;
1223 if (is_handle_aborted(handle
))
1226 if (jbd2_write_access_granted(handle
, bh
, false))
1229 jh
= jbd2_journal_add_journal_head(bh
);
1230 /* We do not want to get caught playing with fields which the
1231 * log thread also manipulates. Make sure that the buffer
1232 * completes any outstanding IO before proceeding. */
1233 rc
= do_get_write_access(handle
, jh
, 0);
1234 jbd2_journal_put_journal_head(jh
);
1240 * When the user wants to journal a newly created buffer_head
1241 * (ie. getblk() returned a new buffer and we are going to populate it
1242 * manually rather than reading off disk), then we need to keep the
1243 * buffer_head locked until it has been completely filled with new
1244 * data. In this case, we should be able to make the assertion that
1245 * the bh is not already part of an existing transaction.
1247 * The buffer should already be locked by the caller by this point.
1248 * There is no lock ranking violation: it was a newly created,
1249 * unlocked buffer beforehand. */
1252 * jbd2_journal_get_create_access () - notify intent to use newly created bh
1253 * @handle: transaction to new buffer to
1256 * Call this if you create a new bh.
1258 int jbd2_journal_get_create_access(handle_t
*handle
, struct buffer_head
*bh
)
1260 transaction_t
*transaction
= handle
->h_transaction
;
1262 struct journal_head
*jh
= jbd2_journal_add_journal_head(bh
);
1265 jbd_debug(5, "journal_head %p\n", jh
);
1267 if (is_handle_aborted(handle
))
1269 journal
= transaction
->t_journal
;
1272 JBUFFER_TRACE(jh
, "entry");
1274 * The buffer may already belong to this transaction due to pre-zeroing
1275 * in the filesystem's new_block code. It may also be on the previous,
1276 * committing transaction's lists, but it HAS to be in Forget state in
1277 * that case: the transaction must have deleted the buffer for it to be
1280 spin_lock(&jh
->b_state_lock
);
1281 J_ASSERT_JH(jh
, (jh
->b_transaction
== transaction
||
1282 jh
->b_transaction
== NULL
||
1283 (jh
->b_transaction
== journal
->j_committing_transaction
&&
1284 jh
->b_jlist
== BJ_Forget
)));
1286 J_ASSERT_JH(jh
, jh
->b_next_transaction
== NULL
);
1287 J_ASSERT_JH(jh
, buffer_locked(jh2bh(jh
)));
1289 if (jh
->b_transaction
== NULL
) {
1291 * Previous jbd2_journal_forget() could have left the buffer
1292 * with jbddirty bit set because it was being committed. When
1293 * the commit finished, we've filed the buffer for
1294 * checkpointing and marked it dirty. Now we are reallocating
1295 * the buffer so the transaction freeing it must have
1296 * committed and so it's safe to clear the dirty bit.
1298 clear_buffer_dirty(jh2bh(jh
));
1299 /* first access by this transaction */
1302 JBUFFER_TRACE(jh
, "file as BJ_Reserved");
1303 spin_lock(&journal
->j_list_lock
);
1304 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Reserved
);
1305 spin_unlock(&journal
->j_list_lock
);
1306 } else if (jh
->b_transaction
== journal
->j_committing_transaction
) {
1307 /* first access by this transaction */
1310 JBUFFER_TRACE(jh
, "set next transaction");
1311 spin_lock(&journal
->j_list_lock
);
1312 jh
->b_next_transaction
= transaction
;
1313 spin_unlock(&journal
->j_list_lock
);
1315 spin_unlock(&jh
->b_state_lock
);
1318 * akpm: I added this. ext3_alloc_branch can pick up new indirect
1319 * blocks which contain freed but then revoked metadata. We need
1320 * to cancel the revoke in case we end up freeing it yet again
1321 * and the reallocating as data - this would cause a second revoke,
1322 * which hits an assertion error.
1324 JBUFFER_TRACE(jh
, "cancelling revoke");
1325 jbd2_journal_cancel_revoke(handle
, jh
);
1327 jbd2_journal_put_journal_head(jh
);
1332 * jbd2_journal_get_undo_access() - Notify intent to modify metadata with
1333 * non-rewindable consequences
1334 * @handle: transaction
1335 * @bh: buffer to undo
1337 * Sometimes there is a need to distinguish between metadata which has
1338 * been committed to disk and that which has not. The ext3fs code uses
1339 * this for freeing and allocating space, we have to make sure that we
1340 * do not reuse freed space until the deallocation has been committed,
1341 * since if we overwrote that space we would make the delete
1342 * un-rewindable in case of a crash.
1344 * To deal with that, jbd2_journal_get_undo_access requests write access to a
1345 * buffer for parts of non-rewindable operations such as delete
1346 * operations on the bitmaps. The journaling code must keep a copy of
1347 * the buffer's contents prior to the undo_access call until such time
1348 * as we know that the buffer has definitely been committed to disk.
1350 * We never need to know which transaction the committed data is part
1351 * of, buffers touched here are guaranteed to be dirtied later and so
1352 * will be committed to a new transaction in due course, at which point
1353 * we can discard the old committed data pointer.
1355 * Returns error number or 0 on success.
1357 int jbd2_journal_get_undo_access(handle_t
*handle
, struct buffer_head
*bh
)
1360 struct journal_head
*jh
;
1361 char *committed_data
= NULL
;
1363 if (is_handle_aborted(handle
))
1366 if (jbd2_write_access_granted(handle
, bh
, true))
1369 jh
= jbd2_journal_add_journal_head(bh
);
1370 JBUFFER_TRACE(jh
, "entry");
1373 * Do this first --- it can drop the journal lock, so we want to
1374 * make sure that obtaining the committed_data is done
1375 * atomically wrt. completion of any outstanding commits.
1377 err
= do_get_write_access(handle
, jh
, 1);
1382 if (!jh
->b_committed_data
)
1383 committed_data
= jbd2_alloc(jh2bh(jh
)->b_size
,
1384 GFP_NOFS
|__GFP_NOFAIL
);
1386 spin_lock(&jh
->b_state_lock
);
1387 if (!jh
->b_committed_data
) {
1388 /* Copy out the current buffer contents into the
1389 * preserved, committed copy. */
1390 JBUFFER_TRACE(jh
, "generate b_committed data");
1391 if (!committed_data
) {
1392 spin_unlock(&jh
->b_state_lock
);
1396 jh
->b_committed_data
= committed_data
;
1397 committed_data
= NULL
;
1398 memcpy(jh
->b_committed_data
, bh
->b_data
, bh
->b_size
);
1400 spin_unlock(&jh
->b_state_lock
);
1402 jbd2_journal_put_journal_head(jh
);
1403 if (unlikely(committed_data
))
1404 jbd2_free(committed_data
, bh
->b_size
);
1409 * jbd2_journal_set_triggers() - Add triggers for commit writeout
1410 * @bh: buffer to trigger on
1411 * @type: struct jbd2_buffer_trigger_type containing the trigger(s).
1413 * Set any triggers on this journal_head. This is always safe, because
1414 * triggers for a committing buffer will be saved off, and triggers for
1415 * a running transaction will match the buffer in that transaction.
1417 * Call with NULL to clear the triggers.
1419 void jbd2_journal_set_triggers(struct buffer_head
*bh
,
1420 struct jbd2_buffer_trigger_type
*type
)
1422 struct journal_head
*jh
= jbd2_journal_grab_journal_head(bh
);
1424 if (WARN_ON_ONCE(!jh
))
1426 jh
->b_triggers
= type
;
1427 jbd2_journal_put_journal_head(jh
);
1430 void jbd2_buffer_frozen_trigger(struct journal_head
*jh
, void *mapped_data
,
1431 struct jbd2_buffer_trigger_type
*triggers
)
1433 struct buffer_head
*bh
= jh2bh(jh
);
1435 if (!triggers
|| !triggers
->t_frozen
)
1438 triggers
->t_frozen(triggers
, bh
, mapped_data
, bh
->b_size
);
1441 void jbd2_buffer_abort_trigger(struct journal_head
*jh
,
1442 struct jbd2_buffer_trigger_type
*triggers
)
1444 if (!triggers
|| !triggers
->t_abort
)
1447 triggers
->t_abort(triggers
, jh2bh(jh
));
1451 * jbd2_journal_dirty_metadata() - mark a buffer as containing dirty metadata
1452 * @handle: transaction to add buffer to.
1453 * @bh: buffer to mark
1455 * mark dirty metadata which needs to be journaled as part of the current
1458 * The buffer must have previously had jbd2_journal_get_write_access()
1459 * called so that it has a valid journal_head attached to the buffer
1462 * The buffer is placed on the transaction's metadata list and is marked
1463 * as belonging to the transaction.
1465 * Returns error number or 0 on success.
1467 * Special care needs to be taken if the buffer already belongs to the
1468 * current committing transaction (in which case we should have frozen
1469 * data present for that commit). In that case, we don't relink the
1470 * buffer: that only gets done when the old transaction finally
1471 * completes its commit.
1473 int jbd2_journal_dirty_metadata(handle_t
*handle
, struct buffer_head
*bh
)
1475 transaction_t
*transaction
= handle
->h_transaction
;
1477 struct journal_head
*jh
;
1480 if (is_handle_aborted(handle
))
1482 if (!buffer_jbd(bh
))
1486 * We don't grab jh reference here since the buffer must be part
1487 * of the running transaction.
1490 jbd_debug(5, "journal_head %p\n", jh
);
1491 JBUFFER_TRACE(jh
, "entry");
1494 * This and the following assertions are unreliable since we may see jh
1495 * in inconsistent state unless we grab bh_state lock. But this is
1496 * crucial to catch bugs so let's do a reliable check until the
1497 * lockless handling is fully proven.
1499 if (data_race(jh
->b_transaction
!= transaction
&&
1500 jh
->b_next_transaction
!= transaction
)) {
1501 spin_lock(&jh
->b_state_lock
);
1502 J_ASSERT_JH(jh
, jh
->b_transaction
== transaction
||
1503 jh
->b_next_transaction
== transaction
);
1504 spin_unlock(&jh
->b_state_lock
);
1506 if (jh
->b_modified
== 1) {
1507 /* If it's in our transaction it must be in BJ_Metadata list. */
1508 if (data_race(jh
->b_transaction
== transaction
&&
1509 jh
->b_jlist
!= BJ_Metadata
)) {
1510 spin_lock(&jh
->b_state_lock
);
1511 if (jh
->b_transaction
== transaction
&&
1512 jh
->b_jlist
!= BJ_Metadata
)
1513 pr_err("JBD2: assertion failure: h_type=%u "
1514 "h_line_no=%u block_no=%llu jlist=%u\n",
1515 handle
->h_type
, handle
->h_line_no
,
1516 (unsigned long long) bh
->b_blocknr
,
1518 J_ASSERT_JH(jh
, jh
->b_transaction
!= transaction
||
1519 jh
->b_jlist
== BJ_Metadata
);
1520 spin_unlock(&jh
->b_state_lock
);
1525 journal
= transaction
->t_journal
;
1526 spin_lock(&jh
->b_state_lock
);
1528 if (jh
->b_modified
== 0) {
1530 * This buffer's got modified and becoming part
1531 * of the transaction. This needs to be done
1532 * once a transaction -bzzz
1534 if (WARN_ON_ONCE(jbd2_handle_buffer_credits(handle
) <= 0)) {
1539 handle
->h_total_credits
--;
1543 * fastpath, to avoid expensive locking. If this buffer is already
1544 * on the running transaction's metadata list there is nothing to do.
1545 * Nobody can take it off again because there is a handle open.
1546 * I _think_ we're OK here with SMP barriers - a mistaken decision will
1547 * result in this test being false, so we go in and take the locks.
1549 if (jh
->b_transaction
== transaction
&& jh
->b_jlist
== BJ_Metadata
) {
1550 JBUFFER_TRACE(jh
, "fastpath");
1551 if (unlikely(jh
->b_transaction
!=
1552 journal
->j_running_transaction
)) {
1553 printk(KERN_ERR
"JBD2: %s: "
1554 "jh->b_transaction (%llu, %p, %u) != "
1555 "journal->j_running_transaction (%p, %u)\n",
1557 (unsigned long long) bh
->b_blocknr
,
1559 jh
->b_transaction
? jh
->b_transaction
->t_tid
: 0,
1560 journal
->j_running_transaction
,
1561 journal
->j_running_transaction
?
1562 journal
->j_running_transaction
->t_tid
: 0);
1568 set_buffer_jbddirty(bh
);
1571 * Metadata already on the current transaction list doesn't
1572 * need to be filed. Metadata on another transaction's list must
1573 * be committing, and will be refiled once the commit completes:
1574 * leave it alone for now.
1576 if (jh
->b_transaction
!= transaction
) {
1577 JBUFFER_TRACE(jh
, "already on other transaction");
1578 if (unlikely(((jh
->b_transaction
!=
1579 journal
->j_committing_transaction
)) ||
1580 (jh
->b_next_transaction
!= transaction
))) {
1581 printk(KERN_ERR
"jbd2_journal_dirty_metadata: %s: "
1582 "bad jh for block %llu: "
1583 "transaction (%p, %u), "
1584 "jh->b_transaction (%p, %u), "
1585 "jh->b_next_transaction (%p, %u), jlist %u\n",
1587 (unsigned long long) bh
->b_blocknr
,
1588 transaction
, transaction
->t_tid
,
1591 jh
->b_transaction
->t_tid
: 0,
1592 jh
->b_next_transaction
,
1593 jh
->b_next_transaction
?
1594 jh
->b_next_transaction
->t_tid
: 0,
1599 /* And this case is illegal: we can't reuse another
1600 * transaction's data buffer, ever. */
1604 /* That test should have eliminated the following case: */
1605 J_ASSERT_JH(jh
, jh
->b_frozen_data
== NULL
);
1607 JBUFFER_TRACE(jh
, "file as BJ_Metadata");
1608 spin_lock(&journal
->j_list_lock
);
1609 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Metadata
);
1610 spin_unlock(&journal
->j_list_lock
);
1612 spin_unlock(&jh
->b_state_lock
);
1614 JBUFFER_TRACE(jh
, "exit");
1619 * jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1620 * @handle: transaction handle
1621 * @bh: bh to 'forget'
1623 * We can only do the bforget if there are no commits pending against the
1624 * buffer. If the buffer is dirty in the current running transaction we
1625 * can safely unlink it.
1627 * bh may not be a journalled buffer at all - it may be a non-JBD
1628 * buffer which came off the hashtable. Check for this.
1630 * Decrements bh->b_count by one.
1632 * Allow this call even if the handle has aborted --- it may be part of
1633 * the caller's cleanup after an abort.
1635 int jbd2_journal_forget(handle_t
*handle
, struct buffer_head
*bh
)
1637 transaction_t
*transaction
= handle
->h_transaction
;
1639 struct journal_head
*jh
;
1640 int drop_reserve
= 0;
1642 int was_modified
= 0;
1644 if (is_handle_aborted(handle
))
1646 journal
= transaction
->t_journal
;
1648 BUFFER_TRACE(bh
, "entry");
1650 jh
= jbd2_journal_grab_journal_head(bh
);
1656 spin_lock(&jh
->b_state_lock
);
1658 /* Critical error: attempting to delete a bitmap buffer, maybe?
1659 * Don't do any jbd operations, and return an error. */
1660 if (!J_EXPECT_JH(jh
, !jh
->b_committed_data
,
1661 "inconsistent data on disk")) {
1666 /* keep track of whether or not this transaction modified us */
1667 was_modified
= jh
->b_modified
;
1670 * The buffer's going from the transaction, we must drop
1671 * all references -bzzz
1675 if (jh
->b_transaction
== transaction
) {
1676 J_ASSERT_JH(jh
, !jh
->b_frozen_data
);
1678 /* If we are forgetting a buffer which is already part
1679 * of this transaction, then we can just drop it from
1680 * the transaction immediately. */
1681 clear_buffer_dirty(bh
);
1682 clear_buffer_jbddirty(bh
);
1684 JBUFFER_TRACE(jh
, "belongs to current transaction: unfile");
1687 * we only want to drop a reference if this transaction
1688 * modified the buffer
1694 * We are no longer going to journal this buffer.
1695 * However, the commit of this transaction is still
1696 * important to the buffer: the delete that we are now
1697 * processing might obsolete an old log entry, so by
1698 * committing, we can satisfy the buffer's checkpoint.
1700 * So, if we have a checkpoint on the buffer, we should
1701 * now refile the buffer on our BJ_Forget list so that
1702 * we know to remove the checkpoint after we commit.
1705 spin_lock(&journal
->j_list_lock
);
1706 if (jh
->b_cp_transaction
) {
1707 __jbd2_journal_temp_unlink_buffer(jh
);
1708 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Forget
);
1710 __jbd2_journal_unfile_buffer(jh
);
1711 jbd2_journal_put_journal_head(jh
);
1713 spin_unlock(&journal
->j_list_lock
);
1714 } else if (jh
->b_transaction
) {
1715 J_ASSERT_JH(jh
, (jh
->b_transaction
==
1716 journal
->j_committing_transaction
));
1717 /* However, if the buffer is still owned by a prior
1718 * (committing) transaction, we can't drop it yet... */
1719 JBUFFER_TRACE(jh
, "belongs to older transaction");
1720 /* ... but we CAN drop it from the new transaction through
1721 * marking the buffer as freed and set j_next_transaction to
1722 * the new transaction, so that not only the commit code
1723 * knows it should clear dirty bits when it is done with the
1724 * buffer, but also the buffer can be checkpointed only
1725 * after the new transaction commits. */
1727 set_buffer_freed(bh
);
1729 if (!jh
->b_next_transaction
) {
1730 spin_lock(&journal
->j_list_lock
);
1731 jh
->b_next_transaction
= transaction
;
1732 spin_unlock(&journal
->j_list_lock
);
1734 J_ASSERT(jh
->b_next_transaction
== transaction
);
1737 * only drop a reference if this transaction modified
1745 * Finally, if the buffer is not belongs to any
1746 * transaction, we can just drop it now if it has no
1749 spin_lock(&journal
->j_list_lock
);
1750 if (!jh
->b_cp_transaction
) {
1751 JBUFFER_TRACE(jh
, "belongs to none transaction");
1752 spin_unlock(&journal
->j_list_lock
);
1757 * Otherwise, if the buffer has been written to disk,
1758 * it is safe to remove the checkpoint and drop it.
1760 if (!buffer_dirty(bh
)) {
1761 __jbd2_journal_remove_checkpoint(jh
);
1762 spin_unlock(&journal
->j_list_lock
);
1767 * The buffer is still not written to disk, we should
1768 * attach this buffer to current transaction so that the
1769 * buffer can be checkpointed only after the current
1770 * transaction commits.
1772 clear_buffer_dirty(bh
);
1773 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Forget
);
1774 spin_unlock(&journal
->j_list_lock
);
1778 spin_unlock(&jh
->b_state_lock
);
1779 jbd2_journal_put_journal_head(jh
);
1781 /* no need to reserve log space for this block -bzzz */
1782 handle
->h_total_credits
++;
1788 * jbd2_journal_stop() - complete a transaction
1789 * @handle: transaction to complete.
1791 * All done for a particular handle.
1793 * There is not much action needed here. We just return any remaining
1794 * buffer credits to the transaction and remove the handle. The only
1795 * complication is that we need to start a commit operation if the
1796 * filesystem is marked for synchronous update.
1798 * jbd2_journal_stop itself will not usually return an error, but it may
1799 * do so in unusual circumstances. In particular, expect it to
1800 * return -EIO if a jbd2_journal_abort has been executed since the
1801 * transaction began.
1803 int jbd2_journal_stop(handle_t
*handle
)
1805 transaction_t
*transaction
= handle
->h_transaction
;
1807 int err
= 0, wait_for_commit
= 0;
1811 if (--handle
->h_ref
> 0) {
1812 jbd_debug(4, "h_ref %d -> %d\n", handle
->h_ref
+ 1,
1814 if (is_handle_aborted(handle
))
1820 * Handle is already detached from the transaction so there is
1821 * nothing to do other than free the handle.
1823 memalloc_nofs_restore(handle
->saved_alloc_context
);
1826 journal
= transaction
->t_journal
;
1827 tid
= transaction
->t_tid
;
1829 if (is_handle_aborted(handle
))
1832 jbd_debug(4, "Handle %p going down\n", handle
);
1833 trace_jbd2_handle_stats(journal
->j_fs_dev
->bd_dev
,
1834 tid
, handle
->h_type
, handle
->h_line_no
,
1835 jiffies
- handle
->h_start_jiffies
,
1836 handle
->h_sync
, handle
->h_requested_credits
,
1837 (handle
->h_requested_credits
-
1838 handle
->h_total_credits
));
1841 * Implement synchronous transaction batching. If the handle
1842 * was synchronous, don't force a commit immediately. Let's
1843 * yield and let another thread piggyback onto this
1844 * transaction. Keep doing that while new threads continue to
1845 * arrive. It doesn't cost much - we're about to run a commit
1846 * and sleep on IO anyway. Speeds up many-threaded, many-dir
1847 * operations by 30x or more...
1849 * We try and optimize the sleep time against what the
1850 * underlying disk can do, instead of having a static sleep
1851 * time. This is useful for the case where our storage is so
1852 * fast that it is more optimal to go ahead and force a flush
1853 * and wait for the transaction to be committed than it is to
1854 * wait for an arbitrary amount of time for new writers to
1855 * join the transaction. We achieve this by measuring how
1856 * long it takes to commit a transaction, and compare it with
1857 * how long this transaction has been running, and if run time
1858 * < commit time then we sleep for the delta and commit. This
1859 * greatly helps super fast disks that would see slowdowns as
1860 * more threads started doing fsyncs.
1862 * But don't do this if this process was the most recent one
1863 * to perform a synchronous write. We do this to detect the
1864 * case where a single process is doing a stream of sync
1865 * writes. No point in waiting for joiners in that case.
1867 * Setting max_batch_time to 0 disables this completely.
1870 if (handle
->h_sync
&& journal
->j_last_sync_writer
!= pid
&&
1871 journal
->j_max_batch_time
) {
1872 u64 commit_time
, trans_time
;
1874 journal
->j_last_sync_writer
= pid
;
1876 read_lock(&journal
->j_state_lock
);
1877 commit_time
= journal
->j_average_commit_time
;
1878 read_unlock(&journal
->j_state_lock
);
1880 trans_time
= ktime_to_ns(ktime_sub(ktime_get(),
1881 transaction
->t_start_time
));
1883 commit_time
= max_t(u64
, commit_time
,
1884 1000*journal
->j_min_batch_time
);
1885 commit_time
= min_t(u64
, commit_time
,
1886 1000*journal
->j_max_batch_time
);
1888 if (trans_time
< commit_time
) {
1889 ktime_t expires
= ktime_add_ns(ktime_get(),
1891 set_current_state(TASK_UNINTERRUPTIBLE
);
1892 schedule_hrtimeout(&expires
, HRTIMER_MODE_ABS
);
1897 transaction
->t_synchronous_commit
= 1;
1900 * If the handle is marked SYNC, we need to set another commit
1901 * going! We also want to force a commit if the transaction is too
1904 if (handle
->h_sync
||
1905 time_after_eq(jiffies
, transaction
->t_expires
)) {
1906 /* Do this even for aborted journals: an abort still
1907 * completes the commit thread, it just doesn't write
1908 * anything to disk. */
1910 jbd_debug(2, "transaction too old, requesting commit for "
1911 "handle %p\n", handle
);
1912 /* This is non-blocking */
1913 jbd2_log_start_commit(journal
, tid
);
1916 * Special case: JBD2_SYNC synchronous updates require us
1917 * to wait for the commit to complete.
1919 if (handle
->h_sync
&& !(current
->flags
& PF_MEMALLOC
))
1920 wait_for_commit
= 1;
1924 * Once stop_this_handle() drops t_updates, the transaction could start
1925 * committing on us and eventually disappear. So we must not
1926 * dereference transaction pointer again after calling
1927 * stop_this_handle().
1929 stop_this_handle(handle
);
1931 if (wait_for_commit
)
1932 err
= jbd2_log_wait_commit(journal
, tid
);
1935 if (handle
->h_rsv_handle
)
1936 jbd2_free_handle(handle
->h_rsv_handle
);
1937 jbd2_free_handle(handle
);
1943 * List management code snippets: various functions for manipulating the
1944 * transaction buffer lists.
1949 * Append a buffer to a transaction list, given the transaction's list head
1952 * j_list_lock is held.
1954 * jh->b_state_lock is held.
1958 __blist_add_buffer(struct journal_head
**list
, struct journal_head
*jh
)
1961 jh
->b_tnext
= jh
->b_tprev
= jh
;
1964 /* Insert at the tail of the list to preserve order */
1965 struct journal_head
*first
= *list
, *last
= first
->b_tprev
;
1967 jh
->b_tnext
= first
;
1968 last
->b_tnext
= first
->b_tprev
= jh
;
1973 * Remove a buffer from a transaction list, given the transaction's list
1976 * Called with j_list_lock held, and the journal may not be locked.
1978 * jh->b_state_lock is held.
1982 __blist_del_buffer(struct journal_head
**list
, struct journal_head
*jh
)
1985 *list
= jh
->b_tnext
;
1989 jh
->b_tprev
->b_tnext
= jh
->b_tnext
;
1990 jh
->b_tnext
->b_tprev
= jh
->b_tprev
;
1994 * Remove a buffer from the appropriate transaction list.
1996 * Note that this function can *change* the value of
1997 * bh->b_transaction->t_buffers, t_forget, t_shadow_list, t_log_list or
1998 * t_reserved_list. If the caller is holding onto a copy of one of these
1999 * pointers, it could go bad. Generally the caller needs to re-read the
2000 * pointer from the transaction_t.
2002 * Called under j_list_lock.
2004 static void __jbd2_journal_temp_unlink_buffer(struct journal_head
*jh
)
2006 struct journal_head
**list
= NULL
;
2007 transaction_t
*transaction
;
2008 struct buffer_head
*bh
= jh2bh(jh
);
2010 lockdep_assert_held(&jh
->b_state_lock
);
2011 transaction
= jh
->b_transaction
;
2013 assert_spin_locked(&transaction
->t_journal
->j_list_lock
);
2015 J_ASSERT_JH(jh
, jh
->b_jlist
< BJ_Types
);
2016 if (jh
->b_jlist
!= BJ_None
)
2017 J_ASSERT_JH(jh
, transaction
!= NULL
);
2019 switch (jh
->b_jlist
) {
2023 transaction
->t_nr_buffers
--;
2024 J_ASSERT_JH(jh
, transaction
->t_nr_buffers
>= 0);
2025 list
= &transaction
->t_buffers
;
2028 list
= &transaction
->t_forget
;
2031 list
= &transaction
->t_shadow_list
;
2034 list
= &transaction
->t_reserved_list
;
2038 __blist_del_buffer(list
, jh
);
2039 jh
->b_jlist
= BJ_None
;
2040 if (transaction
&& is_journal_aborted(transaction
->t_journal
))
2041 clear_buffer_jbddirty(bh
);
2042 else if (test_clear_buffer_jbddirty(bh
))
2043 mark_buffer_dirty(bh
); /* Expose it to the VM */
2047 * Remove buffer from all transactions. The caller is responsible for dropping
2048 * the jh reference that belonged to the transaction.
2050 * Called with bh_state lock and j_list_lock
2052 static void __jbd2_journal_unfile_buffer(struct journal_head
*jh
)
2054 J_ASSERT_JH(jh
, jh
->b_transaction
!= NULL
);
2055 J_ASSERT_JH(jh
, jh
->b_next_transaction
== NULL
);
2057 __jbd2_journal_temp_unlink_buffer(jh
);
2058 jh
->b_transaction
= NULL
;
2061 void jbd2_journal_unfile_buffer(journal_t
*journal
, struct journal_head
*jh
)
2063 struct buffer_head
*bh
= jh2bh(jh
);
2065 /* Get reference so that buffer cannot be freed before we unlock it */
2067 spin_lock(&jh
->b_state_lock
);
2068 spin_lock(&journal
->j_list_lock
);
2069 __jbd2_journal_unfile_buffer(jh
);
2070 spin_unlock(&journal
->j_list_lock
);
2071 spin_unlock(&jh
->b_state_lock
);
2072 jbd2_journal_put_journal_head(jh
);
2077 * Called from jbd2_journal_try_to_free_buffers().
2079 * Called under jh->b_state_lock
2082 __journal_try_to_free_buffer(journal_t
*journal
, struct buffer_head
*bh
)
2084 struct journal_head
*jh
;
2088 if (buffer_locked(bh
) || buffer_dirty(bh
))
2091 if (jh
->b_next_transaction
!= NULL
|| jh
->b_transaction
!= NULL
)
2094 spin_lock(&journal
->j_list_lock
);
2095 if (jh
->b_cp_transaction
!= NULL
) {
2096 /* written-back checkpointed metadata buffer */
2097 JBUFFER_TRACE(jh
, "remove from checkpoint list");
2098 __jbd2_journal_remove_checkpoint(jh
);
2100 spin_unlock(&journal
->j_list_lock
);
2106 * jbd2_journal_try_to_free_buffers() - try to free page buffers.
2107 * @journal: journal for operation
2108 * @page: to try and free
2110 * For all the buffers on this page,
2111 * if they are fully written out ordered data, move them onto BUF_CLEAN
2112 * so try_to_free_buffers() can reap them.
2114 * This function returns non-zero if we wish try_to_free_buffers()
2115 * to be called. We do this if the page is releasable by try_to_free_buffers().
2116 * We also do it if the page has locked or dirty buffers and the caller wants
2117 * us to perform sync or async writeout.
2119 * This complicates JBD locking somewhat. We aren't protected by the
2120 * BKL here. We wish to remove the buffer from its committing or
2121 * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
2123 * This may *change* the value of transaction_t->t_datalist, so anyone
2124 * who looks at t_datalist needs to lock against this function.
2126 * Even worse, someone may be doing a jbd2_journal_dirty_data on this
2127 * buffer. So we need to lock against that. jbd2_journal_dirty_data()
2128 * will come out of the lock with the buffer dirty, which makes it
2129 * ineligible for release here.
2131 * Who else is affected by this? hmm... Really the only contender
2132 * is do_get_write_access() - it could be looking at the buffer while
2133 * journal_try_to_free_buffer() is changing its state. But that
2134 * cannot happen because we never reallocate freed data as metadata
2135 * while the data is part of a transaction. Yes?
2137 * Return 0 on failure, 1 on success
2139 int jbd2_journal_try_to_free_buffers(journal_t
*journal
, struct page
*page
)
2141 struct buffer_head
*head
;
2142 struct buffer_head
*bh
;
2145 J_ASSERT(PageLocked(page
));
2147 head
= page_buffers(page
);
2150 struct journal_head
*jh
;
2153 * We take our own ref against the journal_head here to avoid
2154 * having to add tons of locking around each instance of
2155 * jbd2_journal_put_journal_head().
2157 jh
= jbd2_journal_grab_journal_head(bh
);
2161 spin_lock(&jh
->b_state_lock
);
2162 __journal_try_to_free_buffer(journal
, bh
);
2163 spin_unlock(&jh
->b_state_lock
);
2164 jbd2_journal_put_journal_head(jh
);
2167 } while ((bh
= bh
->b_this_page
) != head
);
2169 ret
= try_to_free_buffers(page
);
2175 * This buffer is no longer needed. If it is on an older transaction's
2176 * checkpoint list we need to record it on this transaction's forget list
2177 * to pin this buffer (and hence its checkpointing transaction) down until
2178 * this transaction commits. If the buffer isn't on a checkpoint list, we
2180 * Returns non-zero if JBD no longer has an interest in the buffer.
2182 * Called under j_list_lock.
2184 * Called under jh->b_state_lock.
2186 static int __dispose_buffer(struct journal_head
*jh
, transaction_t
*transaction
)
2189 struct buffer_head
*bh
= jh2bh(jh
);
2191 if (jh
->b_cp_transaction
) {
2192 JBUFFER_TRACE(jh
, "on running+cp transaction");
2193 __jbd2_journal_temp_unlink_buffer(jh
);
2195 * We don't want to write the buffer anymore, clear the
2196 * bit so that we don't confuse checks in
2197 * __journal_file_buffer
2199 clear_buffer_dirty(bh
);
2200 __jbd2_journal_file_buffer(jh
, transaction
, BJ_Forget
);
2203 JBUFFER_TRACE(jh
, "on running transaction");
2204 __jbd2_journal_unfile_buffer(jh
);
2205 jbd2_journal_put_journal_head(jh
);
2211 * jbd2_journal_invalidatepage
2213 * This code is tricky. It has a number of cases to deal with.
2215 * There are two invariants which this code relies on:
2217 * i_size must be updated on disk before we start calling invalidatepage on the
2220 * This is done in ext3 by defining an ext3_setattr method which
2221 * updates i_size before truncate gets going. By maintaining this
2222 * invariant, we can be sure that it is safe to throw away any buffers
2223 * attached to the current transaction: once the transaction commits,
2224 * we know that the data will not be needed.
2226 * Note however that we can *not* throw away data belonging to the
2227 * previous, committing transaction!
2229 * Any disk blocks which *are* part of the previous, committing
2230 * transaction (and which therefore cannot be discarded immediately) are
2231 * not going to be reused in the new running transaction
2233 * The bitmap committed_data images guarantee this: any block which is
2234 * allocated in one transaction and removed in the next will be marked
2235 * as in-use in the committed_data bitmap, so cannot be reused until
2236 * the next transaction to delete the block commits. This means that
2237 * leaving committing buffers dirty is quite safe: the disk blocks
2238 * cannot be reallocated to a different file and so buffer aliasing is
2242 * The above applies mainly to ordered data mode. In writeback mode we
2243 * don't make guarantees about the order in which data hits disk --- in
2244 * particular we don't guarantee that new dirty data is flushed before
2245 * transaction commit --- so it is always safe just to discard data
2246 * immediately in that mode. --sct
2250 * The journal_unmap_buffer helper function returns zero if the buffer
2251 * concerned remains pinned as an anonymous buffer belonging to an older
2254 * We're outside-transaction here. Either or both of j_running_transaction
2255 * and j_committing_transaction may be NULL.
2257 static int journal_unmap_buffer(journal_t
*journal
, struct buffer_head
*bh
,
2260 transaction_t
*transaction
;
2261 struct journal_head
*jh
;
2264 BUFFER_TRACE(bh
, "entry");
2267 * It is safe to proceed here without the j_list_lock because the
2268 * buffers cannot be stolen by try_to_free_buffers as long as we are
2269 * holding the page lock. --sct
2272 jh
= jbd2_journal_grab_journal_head(bh
);
2274 goto zap_buffer_unlocked
;
2276 /* OK, we have data buffer in journaled mode */
2277 write_lock(&journal
->j_state_lock
);
2278 spin_lock(&jh
->b_state_lock
);
2279 spin_lock(&journal
->j_list_lock
);
2282 * We cannot remove the buffer from checkpoint lists until the
2283 * transaction adding inode to orphan list (let's call it T)
2284 * is committed. Otherwise if the transaction changing the
2285 * buffer would be cleaned from the journal before T is
2286 * committed, a crash will cause that the correct contents of
2287 * the buffer will be lost. On the other hand we have to
2288 * clear the buffer dirty bit at latest at the moment when the
2289 * transaction marking the buffer as freed in the filesystem
2290 * structures is committed because from that moment on the
2291 * block can be reallocated and used by a different page.
2292 * Since the block hasn't been freed yet but the inode has
2293 * already been added to orphan list, it is safe for us to add
2294 * the buffer to BJ_Forget list of the newest transaction.
2296 * Also we have to clear buffer_mapped flag of a truncated buffer
2297 * because the buffer_head may be attached to the page straddling
2298 * i_size (can happen only when blocksize < pagesize) and thus the
2299 * buffer_head can be reused when the file is extended again. So we end
2300 * up keeping around invalidated buffers attached to transactions'
2301 * BJ_Forget list just to stop checkpointing code from cleaning up
2302 * the transaction this buffer was modified in.
2304 transaction
= jh
->b_transaction
;
2305 if (transaction
== NULL
) {
2306 /* First case: not on any transaction. If it
2307 * has no checkpoint link, then we can zap it:
2308 * it's a writeback-mode buffer so we don't care
2309 * if it hits disk safely. */
2310 if (!jh
->b_cp_transaction
) {
2311 JBUFFER_TRACE(jh
, "not on any transaction: zap");
2315 if (!buffer_dirty(bh
)) {
2316 /* bdflush has written it. We can drop it now */
2317 __jbd2_journal_remove_checkpoint(jh
);
2321 /* OK, it must be in the journal but still not
2322 * written fully to disk: it's metadata or
2323 * journaled data... */
2325 if (journal
->j_running_transaction
) {
2326 /* ... and once the current transaction has
2327 * committed, the buffer won't be needed any
2329 JBUFFER_TRACE(jh
, "checkpointed: add to BJ_Forget");
2330 may_free
= __dispose_buffer(jh
,
2331 journal
->j_running_transaction
);
2334 /* There is no currently-running transaction. So the
2335 * orphan record which we wrote for this file must have
2336 * passed into commit. We must attach this buffer to
2337 * the committing transaction, if it exists. */
2338 if (journal
->j_committing_transaction
) {
2339 JBUFFER_TRACE(jh
, "give to committing trans");
2340 may_free
= __dispose_buffer(jh
,
2341 journal
->j_committing_transaction
);
2344 /* The orphan record's transaction has
2345 * committed. We can cleanse this buffer */
2346 clear_buffer_jbddirty(bh
);
2347 __jbd2_journal_remove_checkpoint(jh
);
2351 } else if (transaction
== journal
->j_committing_transaction
) {
2352 JBUFFER_TRACE(jh
, "on committing transaction");
2354 * The buffer is committing, we simply cannot touch
2355 * it. If the page is straddling i_size we have to wait
2356 * for commit and try again.
2359 spin_unlock(&journal
->j_list_lock
);
2360 spin_unlock(&jh
->b_state_lock
);
2361 write_unlock(&journal
->j_state_lock
);
2362 jbd2_journal_put_journal_head(jh
);
2366 * OK, buffer won't be reachable after truncate. We just clear
2367 * b_modified to not confuse transaction credit accounting, and
2368 * set j_next_transaction to the running transaction (if there
2369 * is one) and mark buffer as freed so that commit code knows
2370 * it should clear dirty bits when it is done with the buffer.
2372 set_buffer_freed(bh
);
2373 if (journal
->j_running_transaction
&& buffer_jbddirty(bh
))
2374 jh
->b_next_transaction
= journal
->j_running_transaction
;
2376 spin_unlock(&journal
->j_list_lock
);
2377 spin_unlock(&jh
->b_state_lock
);
2378 write_unlock(&journal
->j_state_lock
);
2379 jbd2_journal_put_journal_head(jh
);
2382 /* Good, the buffer belongs to the running transaction.
2383 * We are writing our own transaction's data, not any
2384 * previous one's, so it is safe to throw it away
2385 * (remember that we expect the filesystem to have set
2386 * i_size already for this truncate so recovery will not
2387 * expose the disk blocks we are discarding here.) */
2388 J_ASSERT_JH(jh
, transaction
== journal
->j_running_transaction
);
2389 JBUFFER_TRACE(jh
, "on running transaction");
2390 may_free
= __dispose_buffer(jh
, transaction
);
2395 * This is tricky. Although the buffer is truncated, it may be reused
2396 * if blocksize < pagesize and it is attached to the page straddling
2397 * EOF. Since the buffer might have been added to BJ_Forget list of the
2398 * running transaction, journal_get_write_access() won't clear
2399 * b_modified and credit accounting gets confused. So clear b_modified
2403 spin_unlock(&journal
->j_list_lock
);
2404 spin_unlock(&jh
->b_state_lock
);
2405 write_unlock(&journal
->j_state_lock
);
2406 jbd2_journal_put_journal_head(jh
);
2407 zap_buffer_unlocked
:
2408 clear_buffer_dirty(bh
);
2409 J_ASSERT_BH(bh
, !buffer_jbddirty(bh
));
2410 clear_buffer_mapped(bh
);
2411 clear_buffer_req(bh
);
2412 clear_buffer_new(bh
);
2413 clear_buffer_delay(bh
);
2414 clear_buffer_unwritten(bh
);
2420 * jbd2_journal_invalidatepage()
2421 * @journal: journal to use for flush...
2422 * @page: page to flush
2423 * @offset: start of the range to invalidate
2424 * @length: length of the range to invalidate
2426 * Reap page buffers containing data after in the specified range in page.
2427 * Can return -EBUSY if buffers are part of the committing transaction and
2428 * the page is straddling i_size. Caller then has to wait for current commit
2431 int jbd2_journal_invalidatepage(journal_t
*journal
,
2433 unsigned int offset
,
2434 unsigned int length
)
2436 struct buffer_head
*head
, *bh
, *next
;
2437 unsigned int stop
= offset
+ length
;
2438 unsigned int curr_off
= 0;
2439 int partial_page
= (offset
|| length
< PAGE_SIZE
);
2443 if (!PageLocked(page
))
2445 if (!page_has_buffers(page
))
2448 BUG_ON(stop
> PAGE_SIZE
|| stop
< length
);
2450 /* We will potentially be playing with lists other than just the
2451 * data lists (especially for journaled data mode), so be
2452 * cautious in our locking. */
2454 head
= bh
= page_buffers(page
);
2456 unsigned int next_off
= curr_off
+ bh
->b_size
;
2457 next
= bh
->b_this_page
;
2459 if (next_off
> stop
)
2462 if (offset
<= curr_off
) {
2463 /* This block is wholly outside the truncation point */
2465 ret
= journal_unmap_buffer(journal
, bh
, partial_page
);
2471 curr_off
= next_off
;
2474 } while (bh
!= head
);
2476 if (!partial_page
) {
2477 if (may_free
&& try_to_free_buffers(page
))
2478 J_ASSERT(!page_has_buffers(page
));
2484 * File a buffer on the given transaction list.
2486 void __jbd2_journal_file_buffer(struct journal_head
*jh
,
2487 transaction_t
*transaction
, int jlist
)
2489 struct journal_head
**list
= NULL
;
2491 struct buffer_head
*bh
= jh2bh(jh
);
2493 lockdep_assert_held(&jh
->b_state_lock
);
2494 assert_spin_locked(&transaction
->t_journal
->j_list_lock
);
2496 J_ASSERT_JH(jh
, jh
->b_jlist
< BJ_Types
);
2497 J_ASSERT_JH(jh
, jh
->b_transaction
== transaction
||
2498 jh
->b_transaction
== NULL
);
2500 if (jh
->b_transaction
&& jh
->b_jlist
== jlist
)
2503 if (jlist
== BJ_Metadata
|| jlist
== BJ_Reserved
||
2504 jlist
== BJ_Shadow
|| jlist
== BJ_Forget
) {
2506 * For metadata buffers, we track dirty bit in buffer_jbddirty
2507 * instead of buffer_dirty. We should not see a dirty bit set
2508 * here because we clear it in do_get_write_access but e.g.
2509 * tune2fs can modify the sb and set the dirty bit at any time
2510 * so we try to gracefully handle that.
2512 if (buffer_dirty(bh
))
2513 warn_dirty_buffer(bh
);
2514 if (test_clear_buffer_dirty(bh
) ||
2515 test_clear_buffer_jbddirty(bh
))
2519 if (jh
->b_transaction
)
2520 __jbd2_journal_temp_unlink_buffer(jh
);
2522 jbd2_journal_grab_journal_head(bh
);
2523 jh
->b_transaction
= transaction
;
2527 J_ASSERT_JH(jh
, !jh
->b_committed_data
);
2528 J_ASSERT_JH(jh
, !jh
->b_frozen_data
);
2531 transaction
->t_nr_buffers
++;
2532 list
= &transaction
->t_buffers
;
2535 list
= &transaction
->t_forget
;
2538 list
= &transaction
->t_shadow_list
;
2541 list
= &transaction
->t_reserved_list
;
2545 __blist_add_buffer(list
, jh
);
2546 jh
->b_jlist
= jlist
;
2549 set_buffer_jbddirty(bh
);
2552 void jbd2_journal_file_buffer(struct journal_head
*jh
,
2553 transaction_t
*transaction
, int jlist
)
2555 spin_lock(&jh
->b_state_lock
);
2556 spin_lock(&transaction
->t_journal
->j_list_lock
);
2557 __jbd2_journal_file_buffer(jh
, transaction
, jlist
);
2558 spin_unlock(&transaction
->t_journal
->j_list_lock
);
2559 spin_unlock(&jh
->b_state_lock
);
2563 * Remove a buffer from its current buffer list in preparation for
2564 * dropping it from its current transaction entirely. If the buffer has
2565 * already started to be used by a subsequent transaction, refile the
2566 * buffer on that transaction's metadata list.
2568 * Called under j_list_lock
2569 * Called under jh->b_state_lock
2571 * When this function returns true, there's no next transaction to refile to
2572 * and the caller has to drop jh reference through
2573 * jbd2_journal_put_journal_head().
2575 bool __jbd2_journal_refile_buffer(struct journal_head
*jh
)
2577 int was_dirty
, jlist
;
2578 struct buffer_head
*bh
= jh2bh(jh
);
2580 lockdep_assert_held(&jh
->b_state_lock
);
2581 if (jh
->b_transaction
)
2582 assert_spin_locked(&jh
->b_transaction
->t_journal
->j_list_lock
);
2584 /* If the buffer is now unused, just drop it. */
2585 if (jh
->b_next_transaction
== NULL
) {
2586 __jbd2_journal_unfile_buffer(jh
);
2591 * It has been modified by a later transaction: add it to the new
2592 * transaction's metadata list.
2595 was_dirty
= test_clear_buffer_jbddirty(bh
);
2596 __jbd2_journal_temp_unlink_buffer(jh
);
2599 * b_transaction must be set, otherwise the new b_transaction won't
2600 * be holding jh reference
2602 J_ASSERT_JH(jh
, jh
->b_transaction
!= NULL
);
2605 * We set b_transaction here because b_next_transaction will inherit
2606 * our jh reference and thus __jbd2_journal_file_buffer() must not
2609 WRITE_ONCE(jh
->b_transaction
, jh
->b_next_transaction
);
2610 WRITE_ONCE(jh
->b_next_transaction
, NULL
);
2611 if (buffer_freed(bh
))
2613 else if (jh
->b_modified
)
2614 jlist
= BJ_Metadata
;
2616 jlist
= BJ_Reserved
;
2617 __jbd2_journal_file_buffer(jh
, jh
->b_transaction
, jlist
);
2618 J_ASSERT_JH(jh
, jh
->b_transaction
->t_state
== T_RUNNING
);
2621 set_buffer_jbddirty(bh
);
2626 * __jbd2_journal_refile_buffer() with necessary locking added. We take our
2627 * bh reference so that we can safely unlock bh.
2629 * The jh and bh may be freed by this call.
2631 void jbd2_journal_refile_buffer(journal_t
*journal
, struct journal_head
*jh
)
2635 spin_lock(&jh
->b_state_lock
);
2636 spin_lock(&journal
->j_list_lock
);
2637 drop
= __jbd2_journal_refile_buffer(jh
);
2638 spin_unlock(&jh
->b_state_lock
);
2639 spin_unlock(&journal
->j_list_lock
);
2641 jbd2_journal_put_journal_head(jh
);
2645 * File inode in the inode list of the handle's transaction
2647 static int jbd2_journal_file_inode(handle_t
*handle
, struct jbd2_inode
*jinode
,
2648 unsigned long flags
, loff_t start_byte
, loff_t end_byte
)
2650 transaction_t
*transaction
= handle
->h_transaction
;
2653 if (is_handle_aborted(handle
))
2655 journal
= transaction
->t_journal
;
2657 jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode
->i_vfs_inode
->i_ino
,
2658 transaction
->t_tid
);
2660 spin_lock(&journal
->j_list_lock
);
2661 jinode
->i_flags
|= flags
;
2663 if (jinode
->i_dirty_end
) {
2664 jinode
->i_dirty_start
= min(jinode
->i_dirty_start
, start_byte
);
2665 jinode
->i_dirty_end
= max(jinode
->i_dirty_end
, end_byte
);
2667 jinode
->i_dirty_start
= start_byte
;
2668 jinode
->i_dirty_end
= end_byte
;
2671 /* Is inode already attached where we need it? */
2672 if (jinode
->i_transaction
== transaction
||
2673 jinode
->i_next_transaction
== transaction
)
2677 * We only ever set this variable to 1 so the test is safe. Since
2678 * t_need_data_flush is likely to be set, we do the test to save some
2679 * cacheline bouncing
2681 if (!transaction
->t_need_data_flush
)
2682 transaction
->t_need_data_flush
= 1;
2683 /* On some different transaction's list - should be
2684 * the committing one */
2685 if (jinode
->i_transaction
) {
2686 J_ASSERT(jinode
->i_next_transaction
== NULL
);
2687 J_ASSERT(jinode
->i_transaction
==
2688 journal
->j_committing_transaction
);
2689 jinode
->i_next_transaction
= transaction
;
2692 /* Not on any transaction list... */
2693 J_ASSERT(!jinode
->i_next_transaction
);
2694 jinode
->i_transaction
= transaction
;
2695 list_add(&jinode
->i_list
, &transaction
->t_inode_list
);
2697 spin_unlock(&journal
->j_list_lock
);
2702 int jbd2_journal_inode_ranged_write(handle_t
*handle
,
2703 struct jbd2_inode
*jinode
, loff_t start_byte
, loff_t length
)
2705 return jbd2_journal_file_inode(handle
, jinode
,
2706 JI_WRITE_DATA
| JI_WAIT_DATA
, start_byte
,
2707 start_byte
+ length
- 1);
2710 int jbd2_journal_inode_ranged_wait(handle_t
*handle
, struct jbd2_inode
*jinode
,
2711 loff_t start_byte
, loff_t length
)
2713 return jbd2_journal_file_inode(handle
, jinode
, JI_WAIT_DATA
,
2714 start_byte
, start_byte
+ length
- 1);
2718 * File truncate and transaction commit interact with each other in a
2719 * non-trivial way. If a transaction writing data block A is
2720 * committing, we cannot discard the data by truncate until we have
2721 * written them. Otherwise if we crashed after the transaction with
2722 * write has committed but before the transaction with truncate has
2723 * committed, we could see stale data in block A. This function is a
2724 * helper to solve this problem. It starts writeout of the truncated
2725 * part in case it is in the committing transaction.
2727 * Filesystem code must call this function when inode is journaled in
2728 * ordered mode before truncation happens and after the inode has been
2729 * placed on orphan list with the new inode size. The second condition
2730 * avoids the race that someone writes new data and we start
2731 * committing the transaction after this function has been called but
2732 * before a transaction for truncate is started (and furthermore it
2733 * allows us to optimize the case where the addition to orphan list
2734 * happens in the same transaction as write --- we don't have to write
2735 * any data in such case).
2737 int jbd2_journal_begin_ordered_truncate(journal_t
*journal
,
2738 struct jbd2_inode
*jinode
,
2741 transaction_t
*inode_trans
, *commit_trans
;
2744 /* This is a quick check to avoid locking if not necessary */
2745 if (!jinode
->i_transaction
)
2747 /* Locks are here just to force reading of recent values, it is
2748 * enough that the transaction was not committing before we started
2749 * a transaction adding the inode to orphan list */
2750 read_lock(&journal
->j_state_lock
);
2751 commit_trans
= journal
->j_committing_transaction
;
2752 read_unlock(&journal
->j_state_lock
);
2753 spin_lock(&journal
->j_list_lock
);
2754 inode_trans
= jinode
->i_transaction
;
2755 spin_unlock(&journal
->j_list_lock
);
2756 if (inode_trans
== commit_trans
) {
2757 ret
= filemap_fdatawrite_range(jinode
->i_vfs_inode
->i_mapping
,
2758 new_size
, LLONG_MAX
);
2760 jbd2_journal_abort(journal
, ret
);