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 * jbd2_get_transaction: obtain a new transaction_t object.
68 * Simply initialise a new transaction. Initialize it in
69 * RUNNING state and add it to the current journal (which should not
70 * have an existing running transaction: we only make a new transaction
71 * once we have started to commit the old one).
74 * The journal MUST be locked. We don't perform atomic mallocs on the
75 * new transaction and we can't block without protecting against other
76 * processes trying to touch the journal while it is in transition.
80 static void jbd2_get_transaction(journal_t *journal,
81 transaction_t *transaction)
83 transaction->t_journal = journal;
84 transaction->t_state = T_RUNNING;
85 transaction->t_start_time = ktime_get();
86 transaction->t_tid = journal->j_transaction_sequence++;
87 transaction->t_expires = jiffies + journal->j_commit_interval;
88 spin_lock_init(&transaction->t_handle_lock);
89 atomic_set(&transaction->t_updates, 0);
90 atomic_set(&transaction->t_outstanding_credits,
91 atomic_read(&journal->j_reserved_credits));
92 atomic_set(&transaction->t_handle_count, 0);
93 INIT_LIST_HEAD(&transaction->t_inode_list);
94 INIT_LIST_HEAD(&transaction->t_private_list);
96 /* Set up the commit timer for the new transaction. */
97 journal->j_commit_timer.expires = round_jiffies_up(transaction->t_expires);
98 add_timer(&journal->j_commit_timer);
100 J_ASSERT(journal->j_running_transaction == NULL);
101 journal->j_running_transaction = transaction;
102 transaction->t_max_wait = 0;
103 transaction->t_start = jiffies;
104 transaction->t_requested = 0;
110 * A handle_t is an object which represents a single atomic update to a
111 * filesystem, and which tracks all of the modifications which form part
112 * of that one update.
116 * Update transaction's maximum wait time, if debugging is enabled.
118 * In order for t_max_wait to be reliable, it must be protected by a
119 * lock. But doing so will mean that start_this_handle() can not be
120 * run in parallel on SMP systems, which limits our scalability. So
121 * unless debugging is enabled, we no longer update t_max_wait, which
122 * means that maximum wait time reported by the jbd2_run_stats
123 * tracepoint will always be zero.
125 static inline void update_t_max_wait(transaction_t *transaction,
128 #ifdef CONFIG_JBD2_DEBUG
129 if (jbd2_journal_enable_debug &&
130 time_after(transaction->t_start, ts)) {
131 ts = jbd2_time_diff(ts, transaction->t_start);
132 spin_lock(&transaction->t_handle_lock);
133 if (ts > transaction->t_max_wait)
134 transaction->t_max_wait = ts;
135 spin_unlock(&transaction->t_handle_lock);
141 * Wait until running transaction passes to T_FLUSH state and new transaction
142 * can thus be started. Also starts the commit if needed. The function expects
143 * running transaction to exist and releases j_state_lock.
145 static void wait_transaction_locked(journal_t *journal)
146 __releases(journal->j_state_lock)
150 tid_t tid = journal->j_running_transaction->t_tid;
152 prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
153 TASK_UNINTERRUPTIBLE);
154 need_to_start = !tid_geq(journal->j_commit_request, tid);
155 read_unlock(&journal->j_state_lock);
157 jbd2_log_start_commit(journal, tid);
158 jbd2_might_wait_for_commit(journal);
160 finish_wait(&journal->j_wait_transaction_locked, &wait);
164 * Wait until running transaction transitions from T_SWITCH to T_FLUSH
165 * state and new transaction can thus be started. The function releases
168 static void wait_transaction_switching(journal_t *journal)
169 __releases(journal->j_state_lock)
173 if (WARN_ON(!journal->j_running_transaction ||
174 journal->j_running_transaction->t_state != T_SWITCH))
176 prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
177 TASK_UNINTERRUPTIBLE);
178 read_unlock(&journal->j_state_lock);
180 * We don't call jbd2_might_wait_for_commit() here as there's no
181 * waiting for outstanding handles happening anymore in T_SWITCH state
182 * and handling of reserved handles actually relies on that for
186 finish_wait(&journal->j_wait_transaction_locked, &wait);
189 static void sub_reserved_credits(journal_t *journal, int blocks)
191 atomic_sub(blocks, &journal->j_reserved_credits);
192 wake_up(&journal->j_wait_reserved);
196 * Wait until we can add credits for handle to the running transaction. Called
197 * with j_state_lock held for reading. Returns 0 if handle joined the running
198 * transaction. Returns 1 if we had to wait, j_state_lock is dropped, and
201 static int add_transaction_credits(journal_t *journal, int blocks,
204 transaction_t *t = journal->j_running_transaction;
206 int total = blocks + rsv_blocks;
209 * If the current transaction is locked down for commit, wait
210 * for the lock to be released.
212 if (t->t_state != T_RUNNING) {
213 WARN_ON_ONCE(t->t_state >= T_FLUSH);
214 wait_transaction_locked(journal);
219 * If there is not enough space left in the log to write all
220 * potential buffers requested by this operation, we need to
221 * stall pending a log checkpoint to free some more log space.
223 needed = atomic_add_return(total, &t->t_outstanding_credits);
224 if (needed > journal->j_max_transaction_buffers) {
226 * If the current transaction is already too large,
227 * then start to commit it: we can then go back and
228 * attach this handle to a new transaction.
230 atomic_sub(total, &t->t_outstanding_credits);
233 * Is the number of reserved credits in the current transaction too
234 * big to fit this handle? Wait until reserved credits are freed.
236 if (atomic_read(&journal->j_reserved_credits) + total >
237 journal->j_max_transaction_buffers) {
238 read_unlock(&journal->j_state_lock);
239 jbd2_might_wait_for_commit(journal);
240 wait_event(journal->j_wait_reserved,
241 atomic_read(&journal->j_reserved_credits) + total <=
242 journal->j_max_transaction_buffers);
246 wait_transaction_locked(journal);
251 * The commit code assumes that it can get enough log space
252 * without forcing a checkpoint. This is *critical* for
253 * correctness: a checkpoint of a buffer which is also
254 * associated with a committing transaction creates a deadlock,
255 * so commit simply cannot force through checkpoints.
257 * We must therefore ensure the necessary space in the journal
258 * *before* starting to dirty potentially checkpointed buffers
259 * in the new transaction.
261 if (jbd2_log_space_left(journal) < jbd2_space_needed(journal)) {
262 atomic_sub(total, &t->t_outstanding_credits);
263 read_unlock(&journal->j_state_lock);
264 jbd2_might_wait_for_commit(journal);
265 write_lock(&journal->j_state_lock);
266 if (jbd2_log_space_left(journal) < jbd2_space_needed(journal))
267 __jbd2_log_wait_for_space(journal);
268 write_unlock(&journal->j_state_lock);
272 /* No reservation? We are done... */
276 needed = atomic_add_return(rsv_blocks, &journal->j_reserved_credits);
277 /* We allow at most half of a transaction to be reserved */
278 if (needed > journal->j_max_transaction_buffers / 2) {
279 sub_reserved_credits(journal, rsv_blocks);
280 atomic_sub(total, &t->t_outstanding_credits);
281 read_unlock(&journal->j_state_lock);
282 jbd2_might_wait_for_commit(journal);
283 wait_event(journal->j_wait_reserved,
284 atomic_read(&journal->j_reserved_credits) + rsv_blocks
285 <= journal->j_max_transaction_buffers / 2);
292 * start_this_handle: Given a handle, deal with any locking or stalling
293 * needed to make sure that there is enough journal space for the handle
294 * to begin. Attach the handle to a transaction and set up the
295 * transaction's buffer credits.
298 static int start_this_handle(journal_t *journal, handle_t *handle,
301 transaction_t *transaction, *new_transaction = NULL;
302 int blocks = handle->h_buffer_credits;
304 unsigned long ts = jiffies;
306 if (handle->h_rsv_handle)
307 rsv_blocks = handle->h_rsv_handle->h_buffer_credits;
310 * Limit the number of reserved credits to 1/2 of maximum transaction
311 * size and limit the number of total credits to not exceed maximum
312 * transaction size per operation.
314 if ((rsv_blocks > journal->j_max_transaction_buffers / 2) ||
315 (rsv_blocks + blocks > journal->j_max_transaction_buffers)) {
316 printk(KERN_ERR "JBD2: %s wants too many credits "
317 "credits:%d rsv_credits:%d max:%d\n",
318 current->comm, blocks, rsv_blocks,
319 journal->j_max_transaction_buffers);
325 if (!journal->j_running_transaction) {
327 * If __GFP_FS is not present, then we may be being called from
328 * inside the fs writeback layer, so we MUST NOT fail.
330 if ((gfp_mask & __GFP_FS) == 0)
331 gfp_mask |= __GFP_NOFAIL;
332 new_transaction = kmem_cache_zalloc(transaction_cache,
334 if (!new_transaction)
338 jbd_debug(3, "New handle %p going live.\n", handle);
341 * We need to hold j_state_lock until t_updates has been incremented,
342 * for proper journal barrier handling
345 read_lock(&journal->j_state_lock);
346 BUG_ON(journal->j_flags & JBD2_UNMOUNT);
347 if (is_journal_aborted(journal) ||
348 (journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) {
349 read_unlock(&journal->j_state_lock);
350 jbd2_journal_free_transaction(new_transaction);
355 * Wait on the journal's transaction barrier if necessary. Specifically
356 * we allow reserved handles to proceed because otherwise commit could
357 * deadlock on page writeback not being able to complete.
359 if (!handle->h_reserved && journal->j_barrier_count) {
360 read_unlock(&journal->j_state_lock);
361 wait_event(journal->j_wait_transaction_locked,
362 journal->j_barrier_count == 0);
366 if (!journal->j_running_transaction) {
367 read_unlock(&journal->j_state_lock);
368 if (!new_transaction)
369 goto alloc_transaction;
370 write_lock(&journal->j_state_lock);
371 if (!journal->j_running_transaction &&
372 (handle->h_reserved || !journal->j_barrier_count)) {
373 jbd2_get_transaction(journal, new_transaction);
374 new_transaction = NULL;
376 write_unlock(&journal->j_state_lock);
380 transaction = journal->j_running_transaction;
382 if (!handle->h_reserved) {
383 /* We may have dropped j_state_lock - restart in that case */
384 if (add_transaction_credits(journal, blocks, rsv_blocks))
388 * We have handle reserved so we are allowed to join T_LOCKED
389 * transaction and we don't have to check for transaction size
390 * and journal space. But we still have to wait while running
391 * transaction is being switched to a committing one as it
392 * won't wait for any handles anymore.
394 if (transaction->t_state == T_SWITCH) {
395 wait_transaction_switching(journal);
398 sub_reserved_credits(journal, blocks);
399 handle->h_reserved = 0;
402 /* OK, account for the buffers that this operation expects to
403 * use and add the handle to the running transaction.
405 update_t_max_wait(transaction, ts);
406 handle->h_transaction = transaction;
407 handle->h_requested_credits = blocks;
408 handle->h_start_jiffies = jiffies;
409 atomic_inc(&transaction->t_updates);
410 atomic_inc(&transaction->t_handle_count);
411 jbd_debug(4, "Handle %p given %d credits (total %d, free %lu)\n",
413 atomic_read(&transaction->t_outstanding_credits),
414 jbd2_log_space_left(journal));
415 read_unlock(&journal->j_state_lock);
416 current->journal_info = handle;
418 rwsem_acquire_read(&journal->j_trans_commit_map, 0, 0, _THIS_IP_);
419 jbd2_journal_free_transaction(new_transaction);
421 * Ensure that no allocations done while the transaction is open are
422 * going to recurse back to the fs layer.
424 handle->saved_alloc_context = memalloc_nofs_save();
428 /* Allocate a new handle. This should probably be in a slab... */
429 static handle_t *new_handle(int nblocks)
431 handle_t *handle = jbd2_alloc_handle(GFP_NOFS);
434 handle->h_buffer_credits = nblocks;
440 handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int rsv_blocks,
441 gfp_t gfp_mask, unsigned int type,
442 unsigned int line_no)
444 handle_t *handle = journal_current_handle();
448 return ERR_PTR(-EROFS);
451 J_ASSERT(handle->h_transaction->t_journal == journal);
456 handle = new_handle(nblocks);
458 return ERR_PTR(-ENOMEM);
460 handle_t *rsv_handle;
462 rsv_handle = new_handle(rsv_blocks);
464 jbd2_free_handle(handle);
465 return ERR_PTR(-ENOMEM);
467 rsv_handle->h_reserved = 1;
468 rsv_handle->h_journal = journal;
469 handle->h_rsv_handle = rsv_handle;
472 err = start_this_handle(journal, handle, gfp_mask);
474 if (handle->h_rsv_handle)
475 jbd2_free_handle(handle->h_rsv_handle);
476 jbd2_free_handle(handle);
479 handle->h_type = type;
480 handle->h_line_no = line_no;
481 trace_jbd2_handle_start(journal->j_fs_dev->bd_dev,
482 handle->h_transaction->t_tid, type,
487 EXPORT_SYMBOL(jbd2__journal_start);
491 * handle_t *jbd2_journal_start() - Obtain a new handle.
492 * @journal: Journal to start transaction on.
493 * @nblocks: number of block buffer we might modify
495 * We make sure that the transaction can guarantee at least nblocks of
496 * modified buffers in the log. We block until the log can guarantee
497 * that much space. Additionally, if rsv_blocks > 0, we also create another
498 * handle with rsv_blocks reserved blocks in the journal. This handle is
499 * is stored in h_rsv_handle. It is not attached to any particular transaction
500 * and thus doesn't block transaction commit. If the caller uses this reserved
501 * handle, it has to set h_rsv_handle to NULL as otherwise jbd2_journal_stop()
502 * on the parent handle will dispose the reserved one. Reserved handle has to
503 * be converted to a normal handle using jbd2_journal_start_reserved() before
506 * Return a pointer to a newly allocated handle, or an ERR_PTR() value
509 handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
511 return jbd2__journal_start(journal, nblocks, 0, GFP_NOFS, 0, 0);
513 EXPORT_SYMBOL(jbd2_journal_start);
515 void jbd2_journal_free_reserved(handle_t *handle)
517 journal_t *journal = handle->h_journal;
519 WARN_ON(!handle->h_reserved);
520 sub_reserved_credits(journal, handle->h_buffer_credits);
521 jbd2_free_handle(handle);
523 EXPORT_SYMBOL(jbd2_journal_free_reserved);
526 * int jbd2_journal_start_reserved() - start reserved handle
527 * @handle: handle to start
528 * @type: for handle statistics
529 * @line_no: for handle statistics
531 * Start handle that has been previously reserved with jbd2_journal_reserve().
532 * This attaches @handle to the running transaction (or creates one if there's
533 * not transaction running). Unlike jbd2_journal_start() this function cannot
534 * block on journal commit, checkpointing, or similar stuff. It can block on
535 * memory allocation or frozen journal though.
537 * Return 0 on success, non-zero on error - handle is freed in that case.
539 int jbd2_journal_start_reserved(handle_t *handle, unsigned int type,
540 unsigned int line_no)
542 journal_t *journal = handle->h_journal;
545 if (WARN_ON(!handle->h_reserved)) {
546 /* Someone passed in normal handle? Just stop it. */
547 jbd2_journal_stop(handle);
551 * Usefulness of mixing of reserved and unreserved handles is
552 * questionable. So far nobody seems to need it so just error out.
554 if (WARN_ON(current->journal_info)) {
555 jbd2_journal_free_reserved(handle);
559 handle->h_journal = NULL;
561 * GFP_NOFS is here because callers are likely from writeback or
562 * similarly constrained call sites
564 ret = start_this_handle(journal, handle, GFP_NOFS);
566 handle->h_journal = journal;
567 jbd2_journal_free_reserved(handle);
570 handle->h_type = type;
571 handle->h_line_no = line_no;
572 trace_jbd2_handle_start(journal->j_fs_dev->bd_dev,
573 handle->h_transaction->t_tid, type,
574 line_no, handle->h_buffer_credits);
577 EXPORT_SYMBOL(jbd2_journal_start_reserved);
580 * int jbd2_journal_extend() - extend buffer credits.
581 * @handle: handle to 'extend'
582 * @nblocks: nr blocks to try to extend by.
584 * Some transactions, such as large extends and truncates, can be done
585 * atomically all at once or in several stages. The operation requests
586 * a credit for a number of buffer modifications in advance, but can
587 * extend its credit if it needs more.
589 * jbd2_journal_extend tries to give the running handle more buffer credits.
590 * It does not guarantee that allocation - this is a best-effort only.
591 * The calling process MUST be able to deal cleanly with a failure to
594 * Return 0 on success, non-zero on failure.
596 * return code < 0 implies an error
597 * return code > 0 implies normal transaction-full status.
599 int jbd2_journal_extend(handle_t *handle, int nblocks)
601 transaction_t *transaction = handle->h_transaction;
606 if (is_handle_aborted(handle))
608 journal = transaction->t_journal;
612 read_lock(&journal->j_state_lock);
614 /* Don't extend a locked-down transaction! */
615 if (transaction->t_state != T_RUNNING) {
616 jbd_debug(3, "denied handle %p %d blocks: "
617 "transaction not running\n", handle, nblocks);
621 spin_lock(&transaction->t_handle_lock);
622 wanted = atomic_add_return(nblocks,
623 &transaction->t_outstanding_credits);
625 if (wanted > journal->j_max_transaction_buffers) {
626 jbd_debug(3, "denied handle %p %d blocks: "
627 "transaction too large\n", handle, nblocks);
628 atomic_sub(nblocks, &transaction->t_outstanding_credits);
632 if (wanted + (wanted >> JBD2_CONTROL_BLOCKS_SHIFT) >
633 jbd2_log_space_left(journal)) {
634 jbd_debug(3, "denied handle %p %d blocks: "
635 "insufficient log space\n", handle, nblocks);
636 atomic_sub(nblocks, &transaction->t_outstanding_credits);
640 trace_jbd2_handle_extend(journal->j_fs_dev->bd_dev,
642 handle->h_type, handle->h_line_no,
643 handle->h_buffer_credits,
646 handle->h_buffer_credits += nblocks;
647 handle->h_requested_credits += nblocks;
650 jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
652 spin_unlock(&transaction->t_handle_lock);
654 read_unlock(&journal->j_state_lock);
660 * int jbd2_journal_restart() - restart a handle .
661 * @handle: handle to restart
662 * @nblocks: nr credits requested
663 * @gfp_mask: memory allocation flags (for start_this_handle)
665 * Restart a handle for a multi-transaction filesystem
668 * If the jbd2_journal_extend() call above fails to grant new buffer credits
669 * to a running handle, a call to jbd2_journal_restart will commit the
670 * handle's transaction so far and reattach the handle to a new
671 * transaction capable of guaranteeing the requested number of
672 * credits. We preserve reserved handle if there's any attached to the
675 int jbd2__journal_restart(handle_t *handle, int nblocks, gfp_t gfp_mask)
677 transaction_t *transaction = handle->h_transaction;
680 int need_to_start, ret;
682 /* If we've had an abort of any type, don't even think about
683 * actually doing the restart! */
684 if (is_handle_aborted(handle))
686 journal = transaction->t_journal;
689 * First unlink the handle from its current transaction, and start the
692 J_ASSERT(atomic_read(&transaction->t_updates) > 0);
693 J_ASSERT(journal_current_handle() == handle);
695 read_lock(&journal->j_state_lock);
696 spin_lock(&transaction->t_handle_lock);
697 atomic_sub(handle->h_buffer_credits,
698 &transaction->t_outstanding_credits);
699 if (handle->h_rsv_handle) {
700 sub_reserved_credits(journal,
701 handle->h_rsv_handle->h_buffer_credits);
703 if (atomic_dec_and_test(&transaction->t_updates))
704 wake_up(&journal->j_wait_updates);
705 tid = transaction->t_tid;
706 spin_unlock(&transaction->t_handle_lock);
707 handle->h_transaction = NULL;
708 current->journal_info = NULL;
710 jbd_debug(2, "restarting handle %p\n", handle);
711 need_to_start = !tid_geq(journal->j_commit_request, tid);
712 read_unlock(&journal->j_state_lock);
714 jbd2_log_start_commit(journal, tid);
716 rwsem_release(&journal->j_trans_commit_map, 1, _THIS_IP_);
717 handle->h_buffer_credits = nblocks;
719 * Restore the original nofs context because the journal restart
720 * is basically the same thing as journal stop and start.
721 * start_this_handle will start a new nofs context.
723 memalloc_nofs_restore(handle->saved_alloc_context);
724 ret = start_this_handle(journal, handle, gfp_mask);
727 EXPORT_SYMBOL(jbd2__journal_restart);
730 int jbd2_journal_restart(handle_t *handle, int nblocks)
732 return jbd2__journal_restart(handle, nblocks, GFP_NOFS);
734 EXPORT_SYMBOL(jbd2_journal_restart);
737 * void jbd2_journal_lock_updates () - establish a transaction barrier.
738 * @journal: Journal to establish a barrier on.
740 * This locks out any further updates from being started, and blocks
741 * until all existing updates have completed, returning only once the
742 * journal is in a quiescent state with no updates running.
744 * The journal lock should not be held on entry.
746 void jbd2_journal_lock_updates(journal_t *journal)
750 jbd2_might_wait_for_commit(journal);
752 write_lock(&journal->j_state_lock);
753 ++journal->j_barrier_count;
755 /* Wait until there are no reserved handles */
756 if (atomic_read(&journal->j_reserved_credits)) {
757 write_unlock(&journal->j_state_lock);
758 wait_event(journal->j_wait_reserved,
759 atomic_read(&journal->j_reserved_credits) == 0);
760 write_lock(&journal->j_state_lock);
763 /* Wait until there are no running updates */
765 transaction_t *transaction = journal->j_running_transaction;
770 spin_lock(&transaction->t_handle_lock);
771 prepare_to_wait(&journal->j_wait_updates, &wait,
772 TASK_UNINTERRUPTIBLE);
773 if (!atomic_read(&transaction->t_updates)) {
774 spin_unlock(&transaction->t_handle_lock);
775 finish_wait(&journal->j_wait_updates, &wait);
778 spin_unlock(&transaction->t_handle_lock);
779 write_unlock(&journal->j_state_lock);
781 finish_wait(&journal->j_wait_updates, &wait);
782 write_lock(&journal->j_state_lock);
784 write_unlock(&journal->j_state_lock);
787 * We have now established a barrier against other normal updates, but
788 * we also need to barrier against other jbd2_journal_lock_updates() calls
789 * to make sure that we serialise special journal-locked operations
792 mutex_lock(&journal->j_barrier);
796 * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier
797 * @journal: Journal to release the barrier on.
799 * Release a transaction barrier obtained with jbd2_journal_lock_updates().
801 * Should be called without the journal lock held.
803 void jbd2_journal_unlock_updates (journal_t *journal)
805 J_ASSERT(journal->j_barrier_count != 0);
807 mutex_unlock(&journal->j_barrier);
808 write_lock(&journal->j_state_lock);
809 --journal->j_barrier_count;
810 write_unlock(&journal->j_state_lock);
811 wake_up(&journal->j_wait_transaction_locked);
814 static void warn_dirty_buffer(struct buffer_head *bh)
817 "JBD2: Spotted dirty metadata buffer (dev = %pg, blocknr = %llu). "
818 "There's a risk of filesystem corruption in case of system "
820 bh->b_bdev, (unsigned long long)bh->b_blocknr);
823 /* Call t_frozen trigger and copy buffer data into jh->b_frozen_data. */
824 static void jbd2_freeze_jh_data(struct journal_head *jh)
829 struct buffer_head *bh = jh2bh(jh);
831 J_EXPECT_JH(jh, buffer_uptodate(bh), "Possible IO failure.\n");
833 offset = offset_in_page(bh->b_data);
834 source = kmap_atomic(page);
835 /* Fire data frozen trigger just before we copy the data */
836 jbd2_buffer_frozen_trigger(jh, source + offset, jh->b_triggers);
837 memcpy(jh->b_frozen_data, source + offset, bh->b_size);
838 kunmap_atomic(source);
841 * Now that the frozen data is saved off, we need to store any matching
844 jh->b_frozen_triggers = jh->b_triggers;
848 * If the buffer is already part of the current transaction, then there
849 * is nothing we need to do. If it is already part of a prior
850 * transaction which we are still committing to disk, then we need to
851 * make sure that we do not overwrite the old copy: we do copy-out to
852 * preserve the copy going to disk. We also account the buffer against
853 * the handle's metadata buffer credits (unless the buffer is already
854 * part of the transaction, that is).
858 do_get_write_access(handle_t *handle, struct journal_head *jh,
861 struct buffer_head *bh;
862 transaction_t *transaction = handle->h_transaction;
865 char *frozen_buffer = NULL;
866 unsigned long start_lock, time_lock;
868 if (is_handle_aborted(handle))
870 journal = transaction->t_journal;
872 jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy);
874 JBUFFER_TRACE(jh, "entry");
878 /* @@@ Need to check for errors here at some point. */
880 start_lock = jiffies;
882 jbd_lock_bh_state(bh);
884 /* If it takes too long to lock the buffer, trace it */
885 time_lock = jbd2_time_diff(start_lock, jiffies);
886 if (time_lock > HZ/10)
887 trace_jbd2_lock_buffer_stall(bh->b_bdev->bd_dev,
888 jiffies_to_msecs(time_lock));
890 /* We now hold the buffer lock so it is safe to query the buffer
891 * state. Is the buffer dirty?
893 * If so, there are two possibilities. The buffer may be
894 * non-journaled, and undergoing a quite legitimate writeback.
895 * Otherwise, it is journaled, and we don't expect dirty buffers
896 * in that state (the buffers should be marked JBD_Dirty
897 * instead.) So either the IO is being done under our own
898 * control and this is a bug, or it's a third party IO such as
899 * dump(8) (which may leave the buffer scheduled for read ---
900 * ie. locked but not dirty) or tune2fs (which may actually have
901 * the buffer dirtied, ugh.) */
903 if (buffer_dirty(bh)) {
905 * First question: is this buffer already part of the current
906 * transaction or the existing committing transaction?
908 if (jh->b_transaction) {
910 jh->b_transaction == transaction ||
912 journal->j_committing_transaction);
913 if (jh->b_next_transaction)
914 J_ASSERT_JH(jh, jh->b_next_transaction ==
916 warn_dirty_buffer(bh);
919 * In any case we need to clean the dirty flag and we must
920 * do it under the buffer lock to be sure we don't race
921 * with running write-out.
923 JBUFFER_TRACE(jh, "Journalling dirty buffer");
924 clear_buffer_dirty(bh);
925 set_buffer_jbddirty(bh);
931 if (is_handle_aborted(handle)) {
932 jbd_unlock_bh_state(bh);
938 * The buffer is already part of this transaction if b_transaction or
939 * b_next_transaction points to it
941 if (jh->b_transaction == transaction ||
942 jh->b_next_transaction == transaction)
946 * this is the first time this transaction is touching this buffer,
947 * reset the modified flag
952 * If the buffer is not journaled right now, we need to make sure it
953 * doesn't get written to disk before the caller actually commits the
956 if (!jh->b_transaction) {
957 JBUFFER_TRACE(jh, "no transaction");
958 J_ASSERT_JH(jh, !jh->b_next_transaction);
959 JBUFFER_TRACE(jh, "file as BJ_Reserved");
961 * Make sure all stores to jh (b_modified, b_frozen_data) are
962 * visible before attaching it to the running transaction.
963 * Paired with barrier in jbd2_write_access_granted()
966 spin_lock(&journal->j_list_lock);
967 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
968 spin_unlock(&journal->j_list_lock);
972 * If there is already a copy-out version of this buffer, then we don't
973 * need to make another one
975 if (jh->b_frozen_data) {
976 JBUFFER_TRACE(jh, "has frozen data");
977 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
981 JBUFFER_TRACE(jh, "owned by older transaction");
982 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
983 J_ASSERT_JH(jh, jh->b_transaction == journal->j_committing_transaction);
986 * There is one case we have to be very careful about. If the
987 * committing transaction is currently writing this buffer out to disk
988 * and has NOT made a copy-out, then we cannot modify the buffer
989 * contents at all right now. The essence of copy-out is that it is
990 * the extra copy, not the primary copy, which gets journaled. If the
991 * primary copy is already going to disk then we cannot do copy-out
994 if (buffer_shadow(bh)) {
995 JBUFFER_TRACE(jh, "on shadow: sleep");
996 jbd_unlock_bh_state(bh);
997 wait_on_bit_io(&bh->b_state, BH_Shadow, TASK_UNINTERRUPTIBLE);
1002 * Only do the copy if the currently-owning transaction still needs it.
1003 * If buffer isn't on BJ_Metadata list, the committing transaction is
1004 * past that stage (here we use the fact that BH_Shadow is set under
1005 * bh_state lock together with refiling to BJ_Shadow list and at this
1006 * point we know the buffer doesn't have BH_Shadow set).
1008 * Subtle point, though: if this is a get_undo_access, then we will be
1009 * relying on the frozen_data to contain the new value of the
1010 * committed_data record after the transaction, so we HAVE to force the
1011 * frozen_data copy in that case.
1013 if (jh->b_jlist == BJ_Metadata || force_copy) {
1014 JBUFFER_TRACE(jh, "generate frozen data");
1015 if (!frozen_buffer) {
1016 JBUFFER_TRACE(jh, "allocate memory for buffer");
1017 jbd_unlock_bh_state(bh);
1018 frozen_buffer = jbd2_alloc(jh2bh(jh)->b_size,
1019 GFP_NOFS | __GFP_NOFAIL);
1022 jh->b_frozen_data = frozen_buffer;
1023 frozen_buffer = NULL;
1024 jbd2_freeze_jh_data(jh);
1028 * Make sure all stores to jh (b_modified, b_frozen_data) are visible
1029 * before attaching it to the running transaction. Paired with barrier
1030 * in jbd2_write_access_granted()
1033 jh->b_next_transaction = transaction;
1036 jbd_unlock_bh_state(bh);
1039 * If we are about to journal a buffer, then any revoke pending on it is
1042 jbd2_journal_cancel_revoke(handle, jh);
1045 if (unlikely(frozen_buffer)) /* It's usually NULL */
1046 jbd2_free(frozen_buffer, bh->b_size);
1048 JBUFFER_TRACE(jh, "exit");
1052 /* Fast check whether buffer is already attached to the required transaction */
1053 static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh,
1056 struct journal_head *jh;
1059 /* Dirty buffers require special handling... */
1060 if (buffer_dirty(bh))
1064 * RCU protects us from dereferencing freed pages. So the checks we do
1065 * are guaranteed not to oops. However the jh slab object can get freed
1066 * & reallocated while we work with it. So we have to be careful. When
1067 * we see jh attached to the running transaction, we know it must stay
1068 * so until the transaction is committed. Thus jh won't be freed and
1069 * will be attached to the same bh while we run. However it can
1070 * happen jh gets freed, reallocated, and attached to the transaction
1071 * just after we get pointer to it from bh. So we have to be careful
1072 * and recheck jh still belongs to our bh before we return success.
1075 if (!buffer_jbd(bh))
1077 /* This should be bh2jh() but that doesn't work with inline functions */
1078 jh = READ_ONCE(bh->b_private);
1081 /* For undo access buffer must have data copied */
1082 if (undo && !jh->b_committed_data)
1084 if (jh->b_transaction != handle->h_transaction &&
1085 jh->b_next_transaction != handle->h_transaction)
1088 * There are two reasons for the barrier here:
1089 * 1) Make sure to fetch b_bh after we did previous checks so that we
1090 * detect when jh went through free, realloc, attach to transaction
1091 * while we were checking. Paired with implicit barrier in that path.
1092 * 2) So that access to bh done after jbd2_write_access_granted()
1093 * doesn't get reordered and see inconsistent state of concurrent
1094 * do_get_write_access().
1097 if (unlikely(jh->b_bh != bh))
1106 * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
1107 * @handle: transaction to add buffer modifications to
1108 * @bh: bh to be used for metadata writes
1110 * Returns: error code or 0 on success.
1112 * In full data journalling mode the buffer may be of type BJ_AsyncData,
1113 * because we're ``write()ing`` a buffer which is also part of a shared mapping.
1116 int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
1118 struct journal_head *jh;
1121 if (jbd2_write_access_granted(handle, bh, false))
1124 jh = jbd2_journal_add_journal_head(bh);
1125 /* We do not want to get caught playing with fields which the
1126 * log thread also manipulates. Make sure that the buffer
1127 * completes any outstanding IO before proceeding. */
1128 rc = do_get_write_access(handle, jh, 0);
1129 jbd2_journal_put_journal_head(jh);
1135 * When the user wants to journal a newly created buffer_head
1136 * (ie. getblk() returned a new buffer and we are going to populate it
1137 * manually rather than reading off disk), then we need to keep the
1138 * buffer_head locked until it has been completely filled with new
1139 * data. In this case, we should be able to make the assertion that
1140 * the bh is not already part of an existing transaction.
1142 * The buffer should already be locked by the caller by this point.
1143 * There is no lock ranking violation: it was a newly created,
1144 * unlocked buffer beforehand. */
1147 * int jbd2_journal_get_create_access () - notify intent to use newly created bh
1148 * @handle: transaction to new buffer to
1151 * Call this if you create a new bh.
1153 int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
1155 transaction_t *transaction = handle->h_transaction;
1157 struct journal_head *jh = jbd2_journal_add_journal_head(bh);
1160 jbd_debug(5, "journal_head %p\n", jh);
1162 if (is_handle_aborted(handle))
1164 journal = transaction->t_journal;
1167 JBUFFER_TRACE(jh, "entry");
1169 * The buffer may already belong to this transaction due to pre-zeroing
1170 * in the filesystem's new_block code. It may also be on the previous,
1171 * committing transaction's lists, but it HAS to be in Forget state in
1172 * that case: the transaction must have deleted the buffer for it to be
1175 jbd_lock_bh_state(bh);
1176 J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
1177 jh->b_transaction == NULL ||
1178 (jh->b_transaction == journal->j_committing_transaction &&
1179 jh->b_jlist == BJ_Forget)));
1181 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1182 J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
1184 if (jh->b_transaction == NULL) {
1186 * Previous jbd2_journal_forget() could have left the buffer
1187 * with jbddirty bit set because it was being committed. When
1188 * the commit finished, we've filed the buffer for
1189 * checkpointing and marked it dirty. Now we are reallocating
1190 * the buffer so the transaction freeing it must have
1191 * committed and so it's safe to clear the dirty bit.
1193 clear_buffer_dirty(jh2bh(jh));
1194 /* first access by this transaction */
1197 JBUFFER_TRACE(jh, "file as BJ_Reserved");
1198 spin_lock(&journal->j_list_lock);
1199 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
1200 spin_unlock(&journal->j_list_lock);
1201 } else if (jh->b_transaction == journal->j_committing_transaction) {
1202 /* first access by this transaction */
1205 JBUFFER_TRACE(jh, "set next transaction");
1206 spin_lock(&journal->j_list_lock);
1207 jh->b_next_transaction = transaction;
1208 spin_unlock(&journal->j_list_lock);
1210 jbd_unlock_bh_state(bh);
1213 * akpm: I added this. ext3_alloc_branch can pick up new indirect
1214 * blocks which contain freed but then revoked metadata. We need
1215 * to cancel the revoke in case we end up freeing it yet again
1216 * and the reallocating as data - this would cause a second revoke,
1217 * which hits an assertion error.
1219 JBUFFER_TRACE(jh, "cancelling revoke");
1220 jbd2_journal_cancel_revoke(handle, jh);
1222 jbd2_journal_put_journal_head(jh);
1227 * int jbd2_journal_get_undo_access() - Notify intent to modify metadata with
1228 * non-rewindable consequences
1229 * @handle: transaction
1230 * @bh: buffer to undo
1232 * Sometimes there is a need to distinguish between metadata which has
1233 * been committed to disk and that which has not. The ext3fs code uses
1234 * this for freeing and allocating space, we have to make sure that we
1235 * do not reuse freed space until the deallocation has been committed,
1236 * since if we overwrote that space we would make the delete
1237 * un-rewindable in case of a crash.
1239 * To deal with that, jbd2_journal_get_undo_access requests write access to a
1240 * buffer for parts of non-rewindable operations such as delete
1241 * operations on the bitmaps. The journaling code must keep a copy of
1242 * the buffer's contents prior to the undo_access call until such time
1243 * as we know that the buffer has definitely been committed to disk.
1245 * We never need to know which transaction the committed data is part
1246 * of, buffers touched here are guaranteed to be dirtied later and so
1247 * will be committed to a new transaction in due course, at which point
1248 * we can discard the old committed data pointer.
1250 * Returns error number or 0 on success.
1252 int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
1255 struct journal_head *jh;
1256 char *committed_data = NULL;
1258 if (jbd2_write_access_granted(handle, bh, true))
1261 jh = jbd2_journal_add_journal_head(bh);
1262 JBUFFER_TRACE(jh, "entry");
1265 * Do this first --- it can drop the journal lock, so we want to
1266 * make sure that obtaining the committed_data is done
1267 * atomically wrt. completion of any outstanding commits.
1269 err = do_get_write_access(handle, jh, 1);
1274 if (!jh->b_committed_data)
1275 committed_data = jbd2_alloc(jh2bh(jh)->b_size,
1276 GFP_NOFS|__GFP_NOFAIL);
1278 jbd_lock_bh_state(bh);
1279 if (!jh->b_committed_data) {
1280 /* Copy out the current buffer contents into the
1281 * preserved, committed copy. */
1282 JBUFFER_TRACE(jh, "generate b_committed data");
1283 if (!committed_data) {
1284 jbd_unlock_bh_state(bh);
1288 jh->b_committed_data = committed_data;
1289 committed_data = NULL;
1290 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
1292 jbd_unlock_bh_state(bh);
1294 jbd2_journal_put_journal_head(jh);
1295 if (unlikely(committed_data))
1296 jbd2_free(committed_data, bh->b_size);
1301 * void jbd2_journal_set_triggers() - Add triggers for commit writeout
1302 * @bh: buffer to trigger on
1303 * @type: struct jbd2_buffer_trigger_type containing the trigger(s).
1305 * Set any triggers on this journal_head. This is always safe, because
1306 * triggers for a committing buffer will be saved off, and triggers for
1307 * a running transaction will match the buffer in that transaction.
1309 * Call with NULL to clear the triggers.
1311 void jbd2_journal_set_triggers(struct buffer_head *bh,
1312 struct jbd2_buffer_trigger_type *type)
1314 struct journal_head *jh = jbd2_journal_grab_journal_head(bh);
1318 jh->b_triggers = type;
1319 jbd2_journal_put_journal_head(jh);
1322 void jbd2_buffer_frozen_trigger(struct journal_head *jh, void *mapped_data,
1323 struct jbd2_buffer_trigger_type *triggers)
1325 struct buffer_head *bh = jh2bh(jh);
1327 if (!triggers || !triggers->t_frozen)
1330 triggers->t_frozen(triggers, bh, mapped_data, bh->b_size);
1333 void jbd2_buffer_abort_trigger(struct journal_head *jh,
1334 struct jbd2_buffer_trigger_type *triggers)
1336 if (!triggers || !triggers->t_abort)
1339 triggers->t_abort(triggers, jh2bh(jh));
1343 * int jbd2_journal_dirty_metadata() - mark a buffer as containing dirty metadata
1344 * @handle: transaction to add buffer to.
1345 * @bh: buffer to mark
1347 * mark dirty metadata which needs to be journaled as part of the current
1350 * The buffer must have previously had jbd2_journal_get_write_access()
1351 * called so that it has a valid journal_head attached to the buffer
1354 * The buffer is placed on the transaction's metadata list and is marked
1355 * as belonging to the transaction.
1357 * Returns error number or 0 on success.
1359 * Special care needs to be taken if the buffer already belongs to the
1360 * current committing transaction (in which case we should have frozen
1361 * data present for that commit). In that case, we don't relink the
1362 * buffer: that only gets done when the old transaction finally
1363 * completes its commit.
1365 int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1367 transaction_t *transaction = handle->h_transaction;
1369 struct journal_head *jh;
1372 if (is_handle_aborted(handle))
1374 if (!buffer_jbd(bh))
1378 * We don't grab jh reference here since the buffer must be part
1379 * of the running transaction.
1382 jbd_debug(5, "journal_head %p\n", jh);
1383 JBUFFER_TRACE(jh, "entry");
1386 * This and the following assertions are unreliable since we may see jh
1387 * in inconsistent state unless we grab bh_state lock. But this is
1388 * crucial to catch bugs so let's do a reliable check until the
1389 * lockless handling is fully proven.
1391 if (jh->b_transaction != transaction &&
1392 jh->b_next_transaction != transaction) {
1393 jbd_lock_bh_state(bh);
1394 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
1395 jh->b_next_transaction == transaction);
1396 jbd_unlock_bh_state(bh);
1398 if (jh->b_modified == 1) {
1399 /* If it's in our transaction it must be in BJ_Metadata list. */
1400 if (jh->b_transaction == transaction &&
1401 jh->b_jlist != BJ_Metadata) {
1402 jbd_lock_bh_state(bh);
1403 if (jh->b_transaction == transaction &&
1404 jh->b_jlist != BJ_Metadata)
1405 pr_err("JBD2: assertion failure: h_type=%u "
1406 "h_line_no=%u block_no=%llu jlist=%u\n",
1407 handle->h_type, handle->h_line_no,
1408 (unsigned long long) bh->b_blocknr,
1410 J_ASSERT_JH(jh, jh->b_transaction != transaction ||
1411 jh->b_jlist == BJ_Metadata);
1412 jbd_unlock_bh_state(bh);
1417 journal = transaction->t_journal;
1418 jbd_lock_bh_state(bh);
1420 if (jh->b_modified == 0) {
1422 * This buffer's got modified and becoming part
1423 * of the transaction. This needs to be done
1424 * once a transaction -bzzz
1426 if (handle->h_buffer_credits <= 0) {
1431 handle->h_buffer_credits--;
1435 * fastpath, to avoid expensive locking. If this buffer is already
1436 * on the running transaction's metadata list there is nothing to do.
1437 * Nobody can take it off again because there is a handle open.
1438 * I _think_ we're OK here with SMP barriers - a mistaken decision will
1439 * result in this test being false, so we go in and take the locks.
1441 if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1442 JBUFFER_TRACE(jh, "fastpath");
1443 if (unlikely(jh->b_transaction !=
1444 journal->j_running_transaction)) {
1445 printk(KERN_ERR "JBD2: %s: "
1446 "jh->b_transaction (%llu, %p, %u) != "
1447 "journal->j_running_transaction (%p, %u)\n",
1449 (unsigned long long) bh->b_blocknr,
1451 jh->b_transaction ? jh->b_transaction->t_tid : 0,
1452 journal->j_running_transaction,
1453 journal->j_running_transaction ?
1454 journal->j_running_transaction->t_tid : 0);
1460 set_buffer_jbddirty(bh);
1463 * Metadata already on the current transaction list doesn't
1464 * need to be filed. Metadata on another transaction's list must
1465 * be committing, and will be refiled once the commit completes:
1466 * leave it alone for now.
1468 if (jh->b_transaction != transaction) {
1469 JBUFFER_TRACE(jh, "already on other transaction");
1470 if (unlikely(((jh->b_transaction !=
1471 journal->j_committing_transaction)) ||
1472 (jh->b_next_transaction != transaction))) {
1473 printk(KERN_ERR "jbd2_journal_dirty_metadata: %s: "
1474 "bad jh for block %llu: "
1475 "transaction (%p, %u), "
1476 "jh->b_transaction (%p, %u), "
1477 "jh->b_next_transaction (%p, %u), jlist %u\n",
1479 (unsigned long long) bh->b_blocknr,
1480 transaction, transaction->t_tid,
1483 jh->b_transaction->t_tid : 0,
1484 jh->b_next_transaction,
1485 jh->b_next_transaction ?
1486 jh->b_next_transaction->t_tid : 0,
1491 /* And this case is illegal: we can't reuse another
1492 * transaction's data buffer, ever. */
1496 /* That test should have eliminated the following case: */
1497 J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
1499 JBUFFER_TRACE(jh, "file as BJ_Metadata");
1500 spin_lock(&journal->j_list_lock);
1501 __jbd2_journal_file_buffer(jh, transaction, BJ_Metadata);
1502 spin_unlock(&journal->j_list_lock);
1504 jbd_unlock_bh_state(bh);
1506 JBUFFER_TRACE(jh, "exit");
1511 * void jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1512 * @handle: transaction handle
1513 * @bh: bh to 'forget'
1515 * We can only do the bforget if there are no commits pending against the
1516 * buffer. If the buffer is dirty in the current running transaction we
1517 * can safely unlink it.
1519 * bh may not be a journalled buffer at all - it may be a non-JBD
1520 * buffer which came off the hashtable. Check for this.
1522 * Decrements bh->b_count by one.
1524 * Allow this call even if the handle has aborted --- it may be part of
1525 * the caller's cleanup after an abort.
1527 int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh)
1529 transaction_t *transaction = handle->h_transaction;
1531 struct journal_head *jh;
1532 int drop_reserve = 0;
1534 int was_modified = 0;
1536 if (is_handle_aborted(handle))
1538 journal = transaction->t_journal;
1540 BUFFER_TRACE(bh, "entry");
1542 jbd_lock_bh_state(bh);
1544 if (!buffer_jbd(bh))
1548 /* Critical error: attempting to delete a bitmap buffer, maybe?
1549 * Don't do any jbd operations, and return an error. */
1550 if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1551 "inconsistent data on disk")) {
1556 /* keep track of whether or not this transaction modified us */
1557 was_modified = jh->b_modified;
1560 * The buffer's going from the transaction, we must drop
1561 * all references -bzzz
1565 if (jh->b_transaction == transaction) {
1566 J_ASSERT_JH(jh, !jh->b_frozen_data);
1568 /* If we are forgetting a buffer which is already part
1569 * of this transaction, then we can just drop it from
1570 * the transaction immediately. */
1571 clear_buffer_dirty(bh);
1572 clear_buffer_jbddirty(bh);
1574 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1577 * we only want to drop a reference if this transaction
1578 * modified the buffer
1584 * We are no longer going to journal this buffer.
1585 * However, the commit of this transaction is still
1586 * important to the buffer: the delete that we are now
1587 * processing might obsolete an old log entry, so by
1588 * committing, we can satisfy the buffer's checkpoint.
1590 * So, if we have a checkpoint on the buffer, we should
1591 * now refile the buffer on our BJ_Forget list so that
1592 * we know to remove the checkpoint after we commit.
1595 spin_lock(&journal->j_list_lock);
1596 if (jh->b_cp_transaction) {
1597 __jbd2_journal_temp_unlink_buffer(jh);
1598 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1600 __jbd2_journal_unfile_buffer(jh);
1601 if (!buffer_jbd(bh)) {
1602 spin_unlock(&journal->j_list_lock);
1606 spin_unlock(&journal->j_list_lock);
1607 } else if (jh->b_transaction) {
1608 J_ASSERT_JH(jh, (jh->b_transaction ==
1609 journal->j_committing_transaction));
1610 /* However, if the buffer is still owned by a prior
1611 * (committing) transaction, we can't drop it yet... */
1612 JBUFFER_TRACE(jh, "belongs to older transaction");
1613 /* ... but we CAN drop it from the new transaction through
1614 * marking the buffer as freed and set j_next_transaction to
1615 * the new transaction, so that not only the commit code
1616 * knows it should clear dirty bits when it is done with the
1617 * buffer, but also the buffer can be checkpointed only
1618 * after the new transaction commits. */
1620 set_buffer_freed(bh);
1622 if (!jh->b_next_transaction) {
1623 spin_lock(&journal->j_list_lock);
1624 jh->b_next_transaction = transaction;
1625 spin_unlock(&journal->j_list_lock);
1627 J_ASSERT(jh->b_next_transaction == transaction);
1630 * only drop a reference if this transaction modified
1638 * Finally, if the buffer is not belongs to any
1639 * transaction, we can just drop it now if it has no
1642 spin_lock(&journal->j_list_lock);
1643 if (!jh->b_cp_transaction) {
1644 JBUFFER_TRACE(jh, "belongs to none transaction");
1645 spin_unlock(&journal->j_list_lock);
1650 * Otherwise, if the buffer has been written to disk,
1651 * it is safe to remove the checkpoint and drop it.
1653 if (!buffer_dirty(bh)) {
1654 __jbd2_journal_remove_checkpoint(jh);
1655 spin_unlock(&journal->j_list_lock);
1660 * The buffer is still not written to disk, we should
1661 * attach this buffer to current transaction so that the
1662 * buffer can be checkpointed only after the current
1663 * transaction commits.
1665 clear_buffer_dirty(bh);
1666 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1667 spin_unlock(&journal->j_list_lock);
1670 jbd_unlock_bh_state(bh);
1674 /* no need to reserve log space for this block -bzzz */
1675 handle->h_buffer_credits++;
1680 jbd_unlock_bh_state(bh);
1686 * int jbd2_journal_stop() - complete a transaction
1687 * @handle: transaction to complete.
1689 * All done for a particular handle.
1691 * There is not much action needed here. We just return any remaining
1692 * buffer credits to the transaction and remove the handle. The only
1693 * complication is that we need to start a commit operation if the
1694 * filesystem is marked for synchronous update.
1696 * jbd2_journal_stop itself will not usually return an error, but it may
1697 * do so in unusual circumstances. In particular, expect it to
1698 * return -EIO if a jbd2_journal_abort has been executed since the
1699 * transaction began.
1701 int jbd2_journal_stop(handle_t *handle)
1703 transaction_t *transaction = handle->h_transaction;
1705 int err = 0, wait_for_commit = 0;
1711 * Handle is already detached from the transaction so
1712 * there is nothing to do other than decrease a refcount,
1713 * or free the handle if refcount drops to zero
1715 if (--handle->h_ref > 0) {
1716 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1720 if (handle->h_rsv_handle)
1721 jbd2_free_handle(handle->h_rsv_handle);
1725 journal = transaction->t_journal;
1727 J_ASSERT(journal_current_handle() == handle);
1729 if (is_handle_aborted(handle))
1732 J_ASSERT(atomic_read(&transaction->t_updates) > 0);
1734 if (--handle->h_ref > 0) {
1735 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1740 jbd_debug(4, "Handle %p going down\n", handle);
1741 trace_jbd2_handle_stats(journal->j_fs_dev->bd_dev,
1743 handle->h_type, handle->h_line_no,
1744 jiffies - handle->h_start_jiffies,
1745 handle->h_sync, handle->h_requested_credits,
1746 (handle->h_requested_credits -
1747 handle->h_buffer_credits));
1750 * Implement synchronous transaction batching. If the handle
1751 * was synchronous, don't force a commit immediately. Let's
1752 * yield and let another thread piggyback onto this
1753 * transaction. Keep doing that while new threads continue to
1754 * arrive. It doesn't cost much - we're about to run a commit
1755 * and sleep on IO anyway. Speeds up many-threaded, many-dir
1756 * operations by 30x or more...
1758 * We try and optimize the sleep time against what the
1759 * underlying disk can do, instead of having a static sleep
1760 * time. This is useful for the case where our storage is so
1761 * fast that it is more optimal to go ahead and force a flush
1762 * and wait for the transaction to be committed than it is to
1763 * wait for an arbitrary amount of time for new writers to
1764 * join the transaction. We achieve this by measuring how
1765 * long it takes to commit a transaction, and compare it with
1766 * how long this transaction has been running, and if run time
1767 * < commit time then we sleep for the delta and commit. This
1768 * greatly helps super fast disks that would see slowdowns as
1769 * more threads started doing fsyncs.
1771 * But don't do this if this process was the most recent one
1772 * to perform a synchronous write. We do this to detect the
1773 * case where a single process is doing a stream of sync
1774 * writes. No point in waiting for joiners in that case.
1776 * Setting max_batch_time to 0 disables this completely.
1779 if (handle->h_sync && journal->j_last_sync_writer != pid &&
1780 journal->j_max_batch_time) {
1781 u64 commit_time, trans_time;
1783 journal->j_last_sync_writer = pid;
1785 read_lock(&journal->j_state_lock);
1786 commit_time = journal->j_average_commit_time;
1787 read_unlock(&journal->j_state_lock);
1789 trans_time = ktime_to_ns(ktime_sub(ktime_get(),
1790 transaction->t_start_time));
1792 commit_time = max_t(u64, commit_time,
1793 1000*journal->j_min_batch_time);
1794 commit_time = min_t(u64, commit_time,
1795 1000*journal->j_max_batch_time);
1797 if (trans_time < commit_time) {
1798 ktime_t expires = ktime_add_ns(ktime_get(),
1800 set_current_state(TASK_UNINTERRUPTIBLE);
1801 schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
1806 transaction->t_synchronous_commit = 1;
1807 current->journal_info = NULL;
1808 atomic_sub(handle->h_buffer_credits,
1809 &transaction->t_outstanding_credits);
1812 * If the handle is marked SYNC, we need to set another commit
1813 * going! We also want to force a commit if the current
1814 * transaction is occupying too much of the log, or if the
1815 * transaction is too old now.
1817 if (handle->h_sync ||
1818 (atomic_read(&transaction->t_outstanding_credits) >
1819 journal->j_max_transaction_buffers) ||
1820 time_after_eq(jiffies, transaction->t_expires)) {
1821 /* Do this even for aborted journals: an abort still
1822 * completes the commit thread, it just doesn't write
1823 * anything to disk. */
1825 jbd_debug(2, "transaction too old, requesting commit for "
1826 "handle %p\n", handle);
1827 /* This is non-blocking */
1828 jbd2_log_start_commit(journal, transaction->t_tid);
1831 * Special case: JBD2_SYNC synchronous updates require us
1832 * to wait for the commit to complete.
1834 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1835 wait_for_commit = 1;
1839 * Once we drop t_updates, if it goes to zero the transaction
1840 * could start committing on us and eventually disappear. So
1841 * once we do this, we must not dereference transaction
1844 tid = transaction->t_tid;
1845 if (atomic_dec_and_test(&transaction->t_updates)) {
1846 wake_up(&journal->j_wait_updates);
1847 if (journal->j_barrier_count)
1848 wake_up(&journal->j_wait_transaction_locked);
1851 rwsem_release(&journal->j_trans_commit_map, 1, _THIS_IP_);
1853 if (wait_for_commit)
1854 err = jbd2_log_wait_commit(journal, tid);
1856 if (handle->h_rsv_handle)
1857 jbd2_journal_free_reserved(handle->h_rsv_handle);
1860 * Scope of the GFP_NOFS context is over here and so we can restore the
1861 * original alloc context.
1863 memalloc_nofs_restore(handle->saved_alloc_context);
1864 jbd2_free_handle(handle);
1870 * List management code snippets: various functions for manipulating the
1871 * transaction buffer lists.
1876 * Append a buffer to a transaction list, given the transaction's list head
1879 * j_list_lock is held.
1881 * jbd_lock_bh_state(jh2bh(jh)) is held.
1885 __blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1888 jh->b_tnext = jh->b_tprev = jh;
1891 /* Insert at the tail of the list to preserve order */
1892 struct journal_head *first = *list, *last = first->b_tprev;
1894 jh->b_tnext = first;
1895 last->b_tnext = first->b_tprev = jh;
1900 * Remove a buffer from a transaction list, given the transaction's list
1903 * Called with j_list_lock held, and the journal may not be locked.
1905 * jbd_lock_bh_state(jh2bh(jh)) is held.
1909 __blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1912 *list = jh->b_tnext;
1916 jh->b_tprev->b_tnext = jh->b_tnext;
1917 jh->b_tnext->b_tprev = jh->b_tprev;
1921 * Remove a buffer from the appropriate transaction list.
1923 * Note that this function can *change* the value of
1924 * bh->b_transaction->t_buffers, t_forget, t_shadow_list, t_log_list or
1925 * t_reserved_list. If the caller is holding onto a copy of one of these
1926 * pointers, it could go bad. Generally the caller needs to re-read the
1927 * pointer from the transaction_t.
1929 * Called under j_list_lock.
1931 static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
1933 struct journal_head **list = NULL;
1934 transaction_t *transaction;
1935 struct buffer_head *bh = jh2bh(jh);
1937 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1938 transaction = jh->b_transaction;
1940 assert_spin_locked(&transaction->t_journal->j_list_lock);
1942 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1943 if (jh->b_jlist != BJ_None)
1944 J_ASSERT_JH(jh, transaction != NULL);
1946 switch (jh->b_jlist) {
1950 transaction->t_nr_buffers--;
1951 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1952 list = &transaction->t_buffers;
1955 list = &transaction->t_forget;
1958 list = &transaction->t_shadow_list;
1961 list = &transaction->t_reserved_list;
1965 __blist_del_buffer(list, jh);
1966 jh->b_jlist = BJ_None;
1967 if (transaction && is_journal_aborted(transaction->t_journal))
1968 clear_buffer_jbddirty(bh);
1969 else if (test_clear_buffer_jbddirty(bh))
1970 mark_buffer_dirty(bh); /* Expose it to the VM */
1974 * Remove buffer from all transactions.
1976 * Called with bh_state lock and j_list_lock
1978 * jh and bh may be already freed when this function returns.
1980 static void __jbd2_journal_unfile_buffer(struct journal_head *jh)
1982 __jbd2_journal_temp_unlink_buffer(jh);
1983 jh->b_transaction = NULL;
1984 jbd2_journal_put_journal_head(jh);
1987 void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1989 struct buffer_head *bh = jh2bh(jh);
1991 /* Get reference so that buffer cannot be freed before we unlock it */
1993 jbd_lock_bh_state(bh);
1994 spin_lock(&journal->j_list_lock);
1995 __jbd2_journal_unfile_buffer(jh);
1996 spin_unlock(&journal->j_list_lock);
1997 jbd_unlock_bh_state(bh);
2002 * Called from jbd2_journal_try_to_free_buffers().
2004 * Called under jbd_lock_bh_state(bh)
2007 __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
2009 struct journal_head *jh;
2013 if (buffer_locked(bh) || buffer_dirty(bh))
2016 if (jh->b_next_transaction != NULL || jh->b_transaction != NULL)
2019 spin_lock(&journal->j_list_lock);
2020 if (jh->b_cp_transaction != NULL) {
2021 /* written-back checkpointed metadata buffer */
2022 JBUFFER_TRACE(jh, "remove from checkpoint list");
2023 __jbd2_journal_remove_checkpoint(jh);
2025 spin_unlock(&journal->j_list_lock);
2031 * int jbd2_journal_try_to_free_buffers() - try to free page buffers.
2032 * @journal: journal for operation
2033 * @page: to try and free
2034 * @gfp_mask: we use the mask to detect how hard should we try to release
2035 * buffers. If __GFP_DIRECT_RECLAIM and __GFP_FS is set, we wait for commit
2036 * code to release the buffers.
2039 * For all the buffers on this page,
2040 * if they are fully written out ordered data, move them onto BUF_CLEAN
2041 * so try_to_free_buffers() can reap them.
2043 * This function returns non-zero if we wish try_to_free_buffers()
2044 * to be called. We do this if the page is releasable by try_to_free_buffers().
2045 * We also do it if the page has locked or dirty buffers and the caller wants
2046 * us to perform sync or async writeout.
2048 * This complicates JBD locking somewhat. We aren't protected by the
2049 * BKL here. We wish to remove the buffer from its committing or
2050 * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
2052 * This may *change* the value of transaction_t->t_datalist, so anyone
2053 * who looks at t_datalist needs to lock against this function.
2055 * Even worse, someone may be doing a jbd2_journal_dirty_data on this
2056 * buffer. So we need to lock against that. jbd2_journal_dirty_data()
2057 * will come out of the lock with the buffer dirty, which makes it
2058 * ineligible for release here.
2060 * Who else is affected by this? hmm... Really the only contender
2061 * is do_get_write_access() - it could be looking at the buffer while
2062 * journal_try_to_free_buffer() is changing its state. But that
2063 * cannot happen because we never reallocate freed data as metadata
2064 * while the data is part of a transaction. Yes?
2066 * Return 0 on failure, 1 on success
2068 int jbd2_journal_try_to_free_buffers(journal_t *journal,
2069 struct page *page, gfp_t gfp_mask)
2071 struct buffer_head *head;
2072 struct buffer_head *bh;
2075 J_ASSERT(PageLocked(page));
2077 head = page_buffers(page);
2080 struct journal_head *jh;
2083 * We take our own ref against the journal_head here to avoid
2084 * having to add tons of locking around each instance of
2085 * jbd2_journal_put_journal_head().
2087 jh = jbd2_journal_grab_journal_head(bh);
2091 jbd_lock_bh_state(bh);
2092 __journal_try_to_free_buffer(journal, bh);
2093 jbd2_journal_put_journal_head(jh);
2094 jbd_unlock_bh_state(bh);
2097 } while ((bh = bh->b_this_page) != head);
2099 ret = try_to_free_buffers(page);
2106 * This buffer is no longer needed. If it is on an older transaction's
2107 * checkpoint list we need to record it on this transaction's forget list
2108 * to pin this buffer (and hence its checkpointing transaction) down until
2109 * this transaction commits. If the buffer isn't on a checkpoint list, we
2111 * Returns non-zero if JBD no longer has an interest in the buffer.
2113 * Called under j_list_lock.
2115 * Called under jbd_lock_bh_state(bh).
2117 static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
2120 struct buffer_head *bh = jh2bh(jh);
2122 if (jh->b_cp_transaction) {
2123 JBUFFER_TRACE(jh, "on running+cp transaction");
2124 __jbd2_journal_temp_unlink_buffer(jh);
2126 * We don't want to write the buffer anymore, clear the
2127 * bit so that we don't confuse checks in
2128 * __journal_file_buffer
2130 clear_buffer_dirty(bh);
2131 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
2134 JBUFFER_TRACE(jh, "on running transaction");
2135 __jbd2_journal_unfile_buffer(jh);
2141 * jbd2_journal_invalidatepage
2143 * This code is tricky. It has a number of cases to deal with.
2145 * There are two invariants which this code relies on:
2147 * i_size must be updated on disk before we start calling invalidatepage on the
2150 * This is done in ext3 by defining an ext3_setattr method which
2151 * updates i_size before truncate gets going. By maintaining this
2152 * invariant, we can be sure that it is safe to throw away any buffers
2153 * attached to the current transaction: once the transaction commits,
2154 * we know that the data will not be needed.
2156 * Note however that we can *not* throw away data belonging to the
2157 * previous, committing transaction!
2159 * Any disk blocks which *are* part of the previous, committing
2160 * transaction (and which therefore cannot be discarded immediately) are
2161 * not going to be reused in the new running transaction
2163 * The bitmap committed_data images guarantee this: any block which is
2164 * allocated in one transaction and removed in the next will be marked
2165 * as in-use in the committed_data bitmap, so cannot be reused until
2166 * the next transaction to delete the block commits. This means that
2167 * leaving committing buffers dirty is quite safe: the disk blocks
2168 * cannot be reallocated to a different file and so buffer aliasing is
2172 * The above applies mainly to ordered data mode. In writeback mode we
2173 * don't make guarantees about the order in which data hits disk --- in
2174 * particular we don't guarantee that new dirty data is flushed before
2175 * transaction commit --- so it is always safe just to discard data
2176 * immediately in that mode. --sct
2180 * The journal_unmap_buffer helper function returns zero if the buffer
2181 * concerned remains pinned as an anonymous buffer belonging to an older
2184 * We're outside-transaction here. Either or both of j_running_transaction
2185 * and j_committing_transaction may be NULL.
2187 static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
2190 transaction_t *transaction;
2191 struct journal_head *jh;
2194 BUFFER_TRACE(bh, "entry");
2197 * It is safe to proceed here without the j_list_lock because the
2198 * buffers cannot be stolen by try_to_free_buffers as long as we are
2199 * holding the page lock. --sct
2202 if (!buffer_jbd(bh))
2203 goto zap_buffer_unlocked;
2205 /* OK, we have data buffer in journaled mode */
2206 write_lock(&journal->j_state_lock);
2207 jbd_lock_bh_state(bh);
2208 spin_lock(&journal->j_list_lock);
2210 jh = jbd2_journal_grab_journal_head(bh);
2212 goto zap_buffer_no_jh;
2215 * We cannot remove the buffer from checkpoint lists until the
2216 * transaction adding inode to orphan list (let's call it T)
2217 * is committed. Otherwise if the transaction changing the
2218 * buffer would be cleaned from the journal before T is
2219 * committed, a crash will cause that the correct contents of
2220 * the buffer will be lost. On the other hand we have to
2221 * clear the buffer dirty bit at latest at the moment when the
2222 * transaction marking the buffer as freed in the filesystem
2223 * structures is committed because from that moment on the
2224 * block can be reallocated and used by a different page.
2225 * Since the block hasn't been freed yet but the inode has
2226 * already been added to orphan list, it is safe for us to add
2227 * the buffer to BJ_Forget list of the newest transaction.
2229 * Also we have to clear buffer_mapped flag of a truncated buffer
2230 * because the buffer_head may be attached to the page straddling
2231 * i_size (can happen only when blocksize < pagesize) and thus the
2232 * buffer_head can be reused when the file is extended again. So we end
2233 * up keeping around invalidated buffers attached to transactions'
2234 * BJ_Forget list just to stop checkpointing code from cleaning up
2235 * the transaction this buffer was modified in.
2237 transaction = jh->b_transaction;
2238 if (transaction == NULL) {
2239 /* First case: not on any transaction. If it
2240 * has no checkpoint link, then we can zap it:
2241 * it's a writeback-mode buffer so we don't care
2242 * if it hits disk safely. */
2243 if (!jh->b_cp_transaction) {
2244 JBUFFER_TRACE(jh, "not on any transaction: zap");
2248 if (!buffer_dirty(bh)) {
2249 /* bdflush has written it. We can drop it now */
2250 __jbd2_journal_remove_checkpoint(jh);
2254 /* OK, it must be in the journal but still not
2255 * written fully to disk: it's metadata or
2256 * journaled data... */
2258 if (journal->j_running_transaction) {
2259 /* ... and once the current transaction has
2260 * committed, the buffer won't be needed any
2262 JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
2263 may_free = __dispose_buffer(jh,
2264 journal->j_running_transaction);
2267 /* There is no currently-running transaction. So the
2268 * orphan record which we wrote for this file must have
2269 * passed into commit. We must attach this buffer to
2270 * the committing transaction, if it exists. */
2271 if (journal->j_committing_transaction) {
2272 JBUFFER_TRACE(jh, "give to committing trans");
2273 may_free = __dispose_buffer(jh,
2274 journal->j_committing_transaction);
2277 /* The orphan record's transaction has
2278 * committed. We can cleanse this buffer */
2279 clear_buffer_jbddirty(bh);
2280 __jbd2_journal_remove_checkpoint(jh);
2284 } else if (transaction == journal->j_committing_transaction) {
2285 JBUFFER_TRACE(jh, "on committing transaction");
2287 * The buffer is committing, we simply cannot touch
2288 * it. If the page is straddling i_size we have to wait
2289 * for commit and try again.
2292 jbd2_journal_put_journal_head(jh);
2293 spin_unlock(&journal->j_list_lock);
2294 jbd_unlock_bh_state(bh);
2295 write_unlock(&journal->j_state_lock);
2299 * OK, buffer won't be reachable after truncate. We just set
2300 * j_next_transaction to the running transaction (if there is
2301 * one) and mark buffer as freed so that commit code knows it
2302 * should clear dirty bits when it is done with the buffer.
2304 set_buffer_freed(bh);
2305 if (journal->j_running_transaction && buffer_jbddirty(bh))
2306 jh->b_next_transaction = journal->j_running_transaction;
2307 jbd2_journal_put_journal_head(jh);
2308 spin_unlock(&journal->j_list_lock);
2309 jbd_unlock_bh_state(bh);
2310 write_unlock(&journal->j_state_lock);
2313 /* Good, the buffer belongs to the running transaction.
2314 * We are writing our own transaction's data, not any
2315 * previous one's, so it is safe to throw it away
2316 * (remember that we expect the filesystem to have set
2317 * i_size already for this truncate so recovery will not
2318 * expose the disk blocks we are discarding here.) */
2319 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
2320 JBUFFER_TRACE(jh, "on running transaction");
2321 may_free = __dispose_buffer(jh, transaction);
2326 * This is tricky. Although the buffer is truncated, it may be reused
2327 * if blocksize < pagesize and it is attached to the page straddling
2328 * EOF. Since the buffer might have been added to BJ_Forget list of the
2329 * running transaction, journal_get_write_access() won't clear
2330 * b_modified and credit accounting gets confused. So clear b_modified
2334 jbd2_journal_put_journal_head(jh);
2336 spin_unlock(&journal->j_list_lock);
2337 jbd_unlock_bh_state(bh);
2338 write_unlock(&journal->j_state_lock);
2339 zap_buffer_unlocked:
2340 clear_buffer_dirty(bh);
2341 J_ASSERT_BH(bh, !buffer_jbddirty(bh));
2342 clear_buffer_mapped(bh);
2343 clear_buffer_req(bh);
2344 clear_buffer_new(bh);
2345 clear_buffer_delay(bh);
2346 clear_buffer_unwritten(bh);
2352 * void jbd2_journal_invalidatepage()
2353 * @journal: journal to use for flush...
2354 * @page: page to flush
2355 * @offset: start of the range to invalidate
2356 * @length: length of the range to invalidate
2358 * Reap page buffers containing data after in the specified range in page.
2359 * Can return -EBUSY if buffers are part of the committing transaction and
2360 * the page is straddling i_size. Caller then has to wait for current commit
2363 int jbd2_journal_invalidatepage(journal_t *journal,
2365 unsigned int offset,
2366 unsigned int length)
2368 struct buffer_head *head, *bh, *next;
2369 unsigned int stop = offset + length;
2370 unsigned int curr_off = 0;
2371 int partial_page = (offset || length < PAGE_SIZE);
2375 if (!PageLocked(page))
2377 if (!page_has_buffers(page))
2380 BUG_ON(stop > PAGE_SIZE || stop < length);
2382 /* We will potentially be playing with lists other than just the
2383 * data lists (especially for journaled data mode), so be
2384 * cautious in our locking. */
2386 head = bh = page_buffers(page);
2388 unsigned int next_off = curr_off + bh->b_size;
2389 next = bh->b_this_page;
2391 if (next_off > stop)
2394 if (offset <= curr_off) {
2395 /* This block is wholly outside the truncation point */
2397 ret = journal_unmap_buffer(journal, bh, partial_page);
2403 curr_off = next_off;
2406 } while (bh != head);
2408 if (!partial_page) {
2409 if (may_free && try_to_free_buffers(page))
2410 J_ASSERT(!page_has_buffers(page));
2416 * File a buffer on the given transaction list.
2418 void __jbd2_journal_file_buffer(struct journal_head *jh,
2419 transaction_t *transaction, int jlist)
2421 struct journal_head **list = NULL;
2423 struct buffer_head *bh = jh2bh(jh);
2425 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2426 assert_spin_locked(&transaction->t_journal->j_list_lock);
2428 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
2429 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
2430 jh->b_transaction == NULL);
2432 if (jh->b_transaction && jh->b_jlist == jlist)
2435 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
2436 jlist == BJ_Shadow || jlist == BJ_Forget) {
2438 * For metadata buffers, we track dirty bit in buffer_jbddirty
2439 * instead of buffer_dirty. We should not see a dirty bit set
2440 * here because we clear it in do_get_write_access but e.g.
2441 * tune2fs can modify the sb and set the dirty bit at any time
2442 * so we try to gracefully handle that.
2444 if (buffer_dirty(bh))
2445 warn_dirty_buffer(bh);
2446 if (test_clear_buffer_dirty(bh) ||
2447 test_clear_buffer_jbddirty(bh))
2451 if (jh->b_transaction)
2452 __jbd2_journal_temp_unlink_buffer(jh);
2454 jbd2_journal_grab_journal_head(bh);
2455 jh->b_transaction = transaction;
2459 J_ASSERT_JH(jh, !jh->b_committed_data);
2460 J_ASSERT_JH(jh, !jh->b_frozen_data);
2463 transaction->t_nr_buffers++;
2464 list = &transaction->t_buffers;
2467 list = &transaction->t_forget;
2470 list = &transaction->t_shadow_list;
2473 list = &transaction->t_reserved_list;
2477 __blist_add_buffer(list, jh);
2478 jh->b_jlist = jlist;
2481 set_buffer_jbddirty(bh);
2484 void jbd2_journal_file_buffer(struct journal_head *jh,
2485 transaction_t *transaction, int jlist)
2487 jbd_lock_bh_state(jh2bh(jh));
2488 spin_lock(&transaction->t_journal->j_list_lock);
2489 __jbd2_journal_file_buffer(jh, transaction, jlist);
2490 spin_unlock(&transaction->t_journal->j_list_lock);
2491 jbd_unlock_bh_state(jh2bh(jh));
2495 * Remove a buffer from its current buffer list in preparation for
2496 * dropping it from its current transaction entirely. If the buffer has
2497 * already started to be used by a subsequent transaction, refile the
2498 * buffer on that transaction's metadata list.
2500 * Called under j_list_lock
2501 * Called under jbd_lock_bh_state(jh2bh(jh))
2503 * jh and bh may be already free when this function returns
2505 void __jbd2_journal_refile_buffer(struct journal_head *jh)
2507 int was_dirty, jlist;
2508 struct buffer_head *bh = jh2bh(jh);
2510 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2511 if (jh->b_transaction)
2512 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2514 /* If the buffer is now unused, just drop it. */
2515 if (jh->b_next_transaction == NULL) {
2516 __jbd2_journal_unfile_buffer(jh);
2521 * It has been modified by a later transaction: add it to the new
2522 * transaction's metadata list.
2525 was_dirty = test_clear_buffer_jbddirty(bh);
2526 __jbd2_journal_temp_unlink_buffer(jh);
2528 * We set b_transaction here because b_next_transaction will inherit
2529 * our jh reference and thus __jbd2_journal_file_buffer() must not
2532 jh->b_transaction = jh->b_next_transaction;
2533 jh->b_next_transaction = NULL;
2534 if (buffer_freed(bh))
2536 else if (jh->b_modified)
2537 jlist = BJ_Metadata;
2539 jlist = BJ_Reserved;
2540 __jbd2_journal_file_buffer(jh, jh->b_transaction, jlist);
2541 J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2544 set_buffer_jbddirty(bh);
2548 * __jbd2_journal_refile_buffer() with necessary locking added. We take our
2549 * bh reference so that we can safely unlock bh.
2551 * The jh and bh may be freed by this call.
2553 void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2555 struct buffer_head *bh = jh2bh(jh);
2557 /* Get reference so that buffer cannot be freed before we unlock it */
2559 jbd_lock_bh_state(bh);
2560 spin_lock(&journal->j_list_lock);
2561 __jbd2_journal_refile_buffer(jh);
2562 jbd_unlock_bh_state(bh);
2563 spin_unlock(&journal->j_list_lock);
2568 * File inode in the inode list of the handle's transaction
2570 static int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode,
2571 unsigned long flags, loff_t start_byte, loff_t end_byte)
2573 transaction_t *transaction = handle->h_transaction;
2576 if (is_handle_aborted(handle))
2578 journal = transaction->t_journal;
2580 jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode->i_vfs_inode->i_ino,
2581 transaction->t_tid);
2583 spin_lock(&journal->j_list_lock);
2584 jinode->i_flags |= flags;
2586 if (jinode->i_dirty_end) {
2587 jinode->i_dirty_start = min(jinode->i_dirty_start, start_byte);
2588 jinode->i_dirty_end = max(jinode->i_dirty_end, end_byte);
2590 jinode->i_dirty_start = start_byte;
2591 jinode->i_dirty_end = end_byte;
2594 /* Is inode already attached where we need it? */
2595 if (jinode->i_transaction == transaction ||
2596 jinode->i_next_transaction == transaction)
2600 * We only ever set this variable to 1 so the test is safe. Since
2601 * t_need_data_flush is likely to be set, we do the test to save some
2602 * cacheline bouncing
2604 if (!transaction->t_need_data_flush)
2605 transaction->t_need_data_flush = 1;
2606 /* On some different transaction's list - should be
2607 * the committing one */
2608 if (jinode->i_transaction) {
2609 J_ASSERT(jinode->i_next_transaction == NULL);
2610 J_ASSERT(jinode->i_transaction ==
2611 journal->j_committing_transaction);
2612 jinode->i_next_transaction = transaction;
2615 /* Not on any transaction list... */
2616 J_ASSERT(!jinode->i_next_transaction);
2617 jinode->i_transaction = transaction;
2618 list_add(&jinode->i_list, &transaction->t_inode_list);
2620 spin_unlock(&journal->j_list_lock);
2625 int jbd2_journal_inode_ranged_write(handle_t *handle,
2626 struct jbd2_inode *jinode, loff_t start_byte, loff_t length)
2628 return jbd2_journal_file_inode(handle, jinode,
2629 JI_WRITE_DATA | JI_WAIT_DATA, start_byte,
2630 start_byte + length - 1);
2633 int jbd2_journal_inode_ranged_wait(handle_t *handle, struct jbd2_inode *jinode,
2634 loff_t start_byte, loff_t length)
2636 return jbd2_journal_file_inode(handle, jinode, JI_WAIT_DATA,
2637 start_byte, start_byte + length - 1);
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);