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1/*
2 * linux/fs/jbd/transaction.c
3 *
4 * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
5 *
6 * Copyright 1998 Red Hat corp --- All Rights Reserved
7 *
8 * This file is part of the Linux kernel and is made available under
9 * the terms of the GNU General Public License, version 2, or at your
10 * option, any later version, incorporated herein by reference.
11 *
12 * Generic filesystem transaction handling code; part of the ext2fs
13 * journaling system.
14 *
15 * This file manages transactions (compound commits managed by the
16 * journaling code) and handles (individual atomic operations by the
17 * filesystem).
18 */
19
20#include <linux/time.h>
21#include <linux/fs.h>
22#include <linux/jbd.h>
23#include <linux/errno.h>
24#include <linux/slab.h>
25#include <linux/timer.h>
26#include <linux/mm.h>
27#include <linux/highmem.h>
28#include <linux/hrtimer.h>
29#include <linux/backing-dev.h>
30
31static void __journal_temp_unlink_buffer(struct journal_head *jh);
32
33/*
34 * get_transaction: obtain a new transaction_t object.
35 *
36 * Simply allocate and initialise a new transaction. Create it in
37 * RUNNING state and add it to the current journal (which should not
38 * have an existing running transaction: we only make a new transaction
39 * once we have started to commit the old one).
40 *
41 * Preconditions:
42 * The journal MUST be locked. We don't perform atomic mallocs on the
43 * new transaction and we can't block without protecting against other
44 * processes trying to touch the journal while it is in transition.
45 *
46 * Called under j_state_lock
47 */
48
49static transaction_t *
50get_transaction(journal_t *journal, transaction_t *transaction)
51{
52 transaction->t_journal = journal;
53 transaction->t_state = T_RUNNING;
54 transaction->t_start_time = ktime_get();
55 transaction->t_tid = journal->j_transaction_sequence++;
56 transaction->t_expires = jiffies + journal->j_commit_interval;
57 spin_lock_init(&transaction->t_handle_lock);
58
59 /* Set up the commit timer for the new transaction. */
60 journal->j_commit_timer.expires =
61 round_jiffies_up(transaction->t_expires);
62 add_timer(&journal->j_commit_timer);
63
64 J_ASSERT(journal->j_running_transaction == NULL);
65 journal->j_running_transaction = transaction;
66
67 return transaction;
68}
69
70/*
71 * Handle management.
72 *
73 * A handle_t is an object which represents a single atomic update to a
74 * filesystem, and which tracks all of the modifications which form part
75 * of that one update.
76 */
77
78/*
79 * start_this_handle: Given a handle, deal with any locking or stalling
80 * needed to make sure that there is enough journal space for the handle
81 * to begin. Attach the handle to a transaction and set up the
82 * transaction's buffer credits.
83 */
84
85static int start_this_handle(journal_t *journal, handle_t *handle)
86{
87 transaction_t *transaction;
88 int needed;
89 int nblocks = handle->h_buffer_credits;
90 transaction_t *new_transaction = NULL;
91 int ret = 0;
92
93 if (nblocks > journal->j_max_transaction_buffers) {
94 printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
95 current->comm, nblocks,
96 journal->j_max_transaction_buffers);
97 ret = -ENOSPC;
98 goto out;
99 }
100
101alloc_transaction:
102 if (!journal->j_running_transaction) {
103 new_transaction = kzalloc(sizeof(*new_transaction), GFP_NOFS);
104 if (!new_transaction) {
105 congestion_wait(BLK_RW_ASYNC, HZ/50);
106 goto alloc_transaction;
107 }
108 }
109
110 jbd_debug(3, "New handle %p going live.\n", handle);
111
112repeat:
113
114 /*
115 * We need to hold j_state_lock until t_updates has been incremented,
116 * for proper journal barrier handling
117 */
118 spin_lock(&journal->j_state_lock);
119repeat_locked:
120 if (is_journal_aborted(journal) ||
121 (journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) {
122 spin_unlock(&journal->j_state_lock);
123 ret = -EROFS;
124 goto out;
125 }
126
127 /* Wait on the journal's transaction barrier if necessary */
128 if (journal->j_barrier_count) {
129 spin_unlock(&journal->j_state_lock);
130 wait_event(journal->j_wait_transaction_locked,
131 journal->j_barrier_count == 0);
132 goto repeat;
133 }
134
135 if (!journal->j_running_transaction) {
136 if (!new_transaction) {
137 spin_unlock(&journal->j_state_lock);
138 goto alloc_transaction;
139 }
140 get_transaction(journal, new_transaction);
141 new_transaction = NULL;
142 }
143
144 transaction = journal->j_running_transaction;
145
146 /*
147 * If the current transaction is locked down for commit, wait for the
148 * lock to be released.
149 */
150 if (transaction->t_state == T_LOCKED) {
151 DEFINE_WAIT(wait);
152
153 prepare_to_wait(&journal->j_wait_transaction_locked,
154 &wait, TASK_UNINTERRUPTIBLE);
155 spin_unlock(&journal->j_state_lock);
156 schedule();
157 finish_wait(&journal->j_wait_transaction_locked, &wait);
158 goto repeat;
159 }
160
161 /*
162 * If there is not enough space left in the log to write all potential
163 * buffers requested by this operation, we need to stall pending a log
164 * checkpoint to free some more log space.
165 */
166 spin_lock(&transaction->t_handle_lock);
167 needed = transaction->t_outstanding_credits + nblocks;
168
169 if (needed > journal->j_max_transaction_buffers) {
170 /*
171 * If the current transaction is already too large, then start
172 * to commit it: we can then go back and attach this handle to
173 * a new transaction.
174 */
175 DEFINE_WAIT(wait);
176
177 jbd_debug(2, "Handle %p starting new commit...\n", handle);
178 spin_unlock(&transaction->t_handle_lock);
179 prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
180 TASK_UNINTERRUPTIBLE);
181 __log_start_commit(journal, transaction->t_tid);
182 spin_unlock(&journal->j_state_lock);
183 schedule();
184 finish_wait(&journal->j_wait_transaction_locked, &wait);
185 goto repeat;
186 }
187
188 /*
189 * The commit code assumes that it can get enough log space
190 * without forcing a checkpoint. This is *critical* for
191 * correctness: a checkpoint of a buffer which is also
192 * associated with a committing transaction creates a deadlock,
193 * so commit simply cannot force through checkpoints.
194 *
195 * We must therefore ensure the necessary space in the journal
196 * *before* starting to dirty potentially checkpointed buffers
197 * in the new transaction.
198 *
199 * The worst part is, any transaction currently committing can
200 * reduce the free space arbitrarily. Be careful to account for
201 * those buffers when checkpointing.
202 */
203
204 /*
205 * @@@ AKPM: This seems rather over-defensive. We're giving commit
206 * a _lot_ of headroom: 1/4 of the journal plus the size of
207 * the committing transaction. Really, we only need to give it
208 * committing_transaction->t_outstanding_credits plus "enough" for
209 * the log control blocks.
210 * Also, this test is inconsistent with the matching one in
211 * journal_extend().
212 */
213 if (__log_space_left(journal) < jbd_space_needed(journal)) {
214 jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
215 spin_unlock(&transaction->t_handle_lock);
216 __log_wait_for_space(journal);
217 goto repeat_locked;
218 }
219
220 /* OK, account for the buffers that this operation expects to
221 * use and add the handle to the running transaction. */
222
223 handle->h_transaction = transaction;
224 transaction->t_outstanding_credits += nblocks;
225 transaction->t_updates++;
226 transaction->t_handle_count++;
227 jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
228 handle, nblocks, transaction->t_outstanding_credits,
229 __log_space_left(journal));
230 spin_unlock(&transaction->t_handle_lock);
231 spin_unlock(&journal->j_state_lock);
232
233 lock_map_acquire(&handle->h_lockdep_map);
234out:
235 if (unlikely(new_transaction)) /* It's usually NULL */
236 kfree(new_transaction);
237 return ret;
238}
239
240static struct lock_class_key jbd_handle_key;
241
242/* Allocate a new handle. This should probably be in a slab... */
243static handle_t *new_handle(int nblocks)
244{
245 handle_t *handle = jbd_alloc_handle(GFP_NOFS);
246 if (!handle)
247 return NULL;
248 memset(handle, 0, sizeof(*handle));
249 handle->h_buffer_credits = nblocks;
250 handle->h_ref = 1;
251
252 lockdep_init_map(&handle->h_lockdep_map, "jbd_handle", &jbd_handle_key, 0);
253
254 return handle;
255}
256
257/**
258 * handle_t *journal_start() - Obtain a new handle.
259 * @journal: Journal to start transaction on.
260 * @nblocks: number of block buffer we might modify
261 *
262 * We make sure that the transaction can guarantee at least nblocks of
263 * modified buffers in the log. We block until the log can guarantee
264 * that much space.
265 *
266 * This function is visible to journal users (like ext3fs), so is not
267 * called with the journal already locked.
268 *
269 * Return a pointer to a newly allocated handle, or an ERR_PTR() value
270 * on failure.
271 */
272handle_t *journal_start(journal_t *journal, int nblocks)
273{
274 handle_t *handle = journal_current_handle();
275 int err;
276
277 if (!journal)
278 return ERR_PTR(-EROFS);
279
280 if (handle) {
281 J_ASSERT(handle->h_transaction->t_journal == journal);
282 handle->h_ref++;
283 return handle;
284 }
285
286 handle = new_handle(nblocks);
287 if (!handle)
288 return ERR_PTR(-ENOMEM);
289
290 current->journal_info = handle;
291
292 err = start_this_handle(journal, handle);
293 if (err < 0) {
294 jbd_free_handle(handle);
295 current->journal_info = NULL;
296 handle = ERR_PTR(err);
297 }
298 return handle;
299}
300
301/**
302 * int journal_extend() - extend buffer credits.
303 * @handle: handle to 'extend'
304 * @nblocks: nr blocks to try to extend by.
305 *
306 * Some transactions, such as large extends and truncates, can be done
307 * atomically all at once or in several stages. The operation requests
308 * a credit for a number of buffer modications in advance, but can
309 * extend its credit if it needs more.
310 *
311 * journal_extend tries to give the running handle more buffer credits.
312 * It does not guarantee that allocation - this is a best-effort only.
313 * The calling process MUST be able to deal cleanly with a failure to
314 * extend here.
315 *
316 * Return 0 on success, non-zero on failure.
317 *
318 * return code < 0 implies an error
319 * return code > 0 implies normal transaction-full status.
320 */
321int journal_extend(handle_t *handle, int nblocks)
322{
323 transaction_t *transaction = handle->h_transaction;
324 journal_t *journal = transaction->t_journal;
325 int result;
326 int wanted;
327
328 result = -EIO;
329 if (is_handle_aborted(handle))
330 goto out;
331
332 result = 1;
333
334 spin_lock(&journal->j_state_lock);
335
336 /* Don't extend a locked-down transaction! */
337 if (handle->h_transaction->t_state != T_RUNNING) {
338 jbd_debug(3, "denied handle %p %d blocks: "
339 "transaction not running\n", handle, nblocks);
340 goto error_out;
341 }
342
343 spin_lock(&transaction->t_handle_lock);
344 wanted = transaction->t_outstanding_credits + nblocks;
345
346 if (wanted > journal->j_max_transaction_buffers) {
347 jbd_debug(3, "denied handle %p %d blocks: "
348 "transaction too large\n", handle, nblocks);
349 goto unlock;
350 }
351
352 if (wanted > __log_space_left(journal)) {
353 jbd_debug(3, "denied handle %p %d blocks: "
354 "insufficient log space\n", handle, nblocks);
355 goto unlock;
356 }
357
358 handle->h_buffer_credits += nblocks;
359 transaction->t_outstanding_credits += nblocks;
360 result = 0;
361
362 jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
363unlock:
364 spin_unlock(&transaction->t_handle_lock);
365error_out:
366 spin_unlock(&journal->j_state_lock);
367out:
368 return result;
369}
370
371
372/**
373 * int journal_restart() - restart a handle.
374 * @handle: handle to restart
375 * @nblocks: nr credits requested
376 *
377 * Restart a handle for a multi-transaction filesystem
378 * operation.
379 *
380 * If the journal_extend() call above fails to grant new buffer credits
381 * to a running handle, a call to journal_restart will commit the
382 * handle's transaction so far and reattach the handle to a new
383 * transaction capabable of guaranteeing the requested number of
384 * credits.
385 */
386
387int journal_restart(handle_t *handle, int nblocks)
388{
389 transaction_t *transaction = handle->h_transaction;
390 journal_t *journal = transaction->t_journal;
391 int ret;
392
393 /* If we've had an abort of any type, don't even think about
394 * actually doing the restart! */
395 if (is_handle_aborted(handle))
396 return 0;
397
398 /*
399 * First unlink the handle from its current transaction, and start the
400 * commit on that.
401 */
402 J_ASSERT(transaction->t_updates > 0);
403 J_ASSERT(journal_current_handle() == handle);
404
405 spin_lock(&journal->j_state_lock);
406 spin_lock(&transaction->t_handle_lock);
407 transaction->t_outstanding_credits -= handle->h_buffer_credits;
408 transaction->t_updates--;
409
410 if (!transaction->t_updates)
411 wake_up(&journal->j_wait_updates);
412 spin_unlock(&transaction->t_handle_lock);
413
414 jbd_debug(2, "restarting handle %p\n", handle);
415 __log_start_commit(journal, transaction->t_tid);
416 spin_unlock(&journal->j_state_lock);
417
418 lock_map_release(&handle->h_lockdep_map);
419 handle->h_buffer_credits = nblocks;
420 ret = start_this_handle(journal, handle);
421 return ret;
422}
423
424
425/**
426 * void journal_lock_updates () - establish a transaction barrier.
427 * @journal: Journal to establish a barrier on.
428 *
429 * This locks out any further updates from being started, and blocks until all
430 * existing updates have completed, returning only once the journal is in a
431 * quiescent state with no updates running.
432 *
433 * We do not use simple mutex for synchronization as there are syscalls which
434 * want to return with filesystem locked and that trips up lockdep. Also
435 * hibernate needs to lock filesystem but locked mutex then blocks hibernation.
436 * Since locking filesystem is rare operation, we use simple counter and
437 * waitqueue for locking.
438 */
439void journal_lock_updates(journal_t *journal)
440{
441 DEFINE_WAIT(wait);
442
443wait:
444 /* Wait for previous locked operation to finish */
445 wait_event(journal->j_wait_transaction_locked,
446 journal->j_barrier_count == 0);
447
448 spin_lock(&journal->j_state_lock);
449 /*
450 * Check reliably under the lock whether we are the ones winning the race
451 * and locking the journal
452 */
453 if (journal->j_barrier_count > 0) {
454 spin_unlock(&journal->j_state_lock);
455 goto wait;
456 }
457 ++journal->j_barrier_count;
458
459 /* Wait until there are no running updates */
460 while (1) {
461 transaction_t *transaction = journal->j_running_transaction;
462
463 if (!transaction)
464 break;
465
466 spin_lock(&transaction->t_handle_lock);
467 if (!transaction->t_updates) {
468 spin_unlock(&transaction->t_handle_lock);
469 break;
470 }
471 prepare_to_wait(&journal->j_wait_updates, &wait,
472 TASK_UNINTERRUPTIBLE);
473 spin_unlock(&transaction->t_handle_lock);
474 spin_unlock(&journal->j_state_lock);
475 schedule();
476 finish_wait(&journal->j_wait_updates, &wait);
477 spin_lock(&journal->j_state_lock);
478 }
479 spin_unlock(&journal->j_state_lock);
480}
481
482/**
483 * void journal_unlock_updates (journal_t* journal) - release barrier
484 * @journal: Journal to release the barrier on.
485 *
486 * Release a transaction barrier obtained with journal_lock_updates().
487 */
488void journal_unlock_updates (journal_t *journal)
489{
490 J_ASSERT(journal->j_barrier_count != 0);
491
492 spin_lock(&journal->j_state_lock);
493 --journal->j_barrier_count;
494 spin_unlock(&journal->j_state_lock);
495 wake_up(&journal->j_wait_transaction_locked);
496}
497
498static void warn_dirty_buffer(struct buffer_head *bh)
499{
500 char b[BDEVNAME_SIZE];
501
502 printk(KERN_WARNING
503 "JBD: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). "
504 "There's a risk of filesystem corruption in case of system "
505 "crash.\n",
506 bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr);
507}
508
509/*
510 * If the buffer is already part of the current transaction, then there
511 * is nothing we need to do. If it is already part of a prior
512 * transaction which we are still committing to disk, then we need to
513 * make sure that we do not overwrite the old copy: we do copy-out to
514 * preserve the copy going to disk. We also account the buffer against
515 * the handle's metadata buffer credits (unless the buffer is already
516 * part of the transaction, that is).
517 *
518 */
519static int
520do_get_write_access(handle_t *handle, struct journal_head *jh,
521 int force_copy)
522{
523 struct buffer_head *bh;
524 transaction_t *transaction;
525 journal_t *journal;
526 int error;
527 char *frozen_buffer = NULL;
528 int need_copy = 0;
529
530 if (is_handle_aborted(handle))
531 return -EROFS;
532
533 transaction = handle->h_transaction;
534 journal = transaction->t_journal;
535
536 jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy);
537
538 JBUFFER_TRACE(jh, "entry");
539repeat:
540 bh = jh2bh(jh);
541
542 /* @@@ Need to check for errors here at some point. */
543
544 lock_buffer(bh);
545 jbd_lock_bh_state(bh);
546
547 /* We now hold the buffer lock so it is safe to query the buffer
548 * state. Is the buffer dirty?
549 *
550 * If so, there are two possibilities. The buffer may be
551 * non-journaled, and undergoing a quite legitimate writeback.
552 * Otherwise, it is journaled, and we don't expect dirty buffers
553 * in that state (the buffers should be marked JBD_Dirty
554 * instead.) So either the IO is being done under our own
555 * control and this is a bug, or it's a third party IO such as
556 * dump(8) (which may leave the buffer scheduled for read ---
557 * ie. locked but not dirty) or tune2fs (which may actually have
558 * the buffer dirtied, ugh.) */
559
560 if (buffer_dirty(bh)) {
561 /*
562 * First question: is this buffer already part of the current
563 * transaction or the existing committing transaction?
564 */
565 if (jh->b_transaction) {
566 J_ASSERT_JH(jh,
567 jh->b_transaction == transaction ||
568 jh->b_transaction ==
569 journal->j_committing_transaction);
570 if (jh->b_next_transaction)
571 J_ASSERT_JH(jh, jh->b_next_transaction ==
572 transaction);
573 warn_dirty_buffer(bh);
574 }
575 /*
576 * In any case we need to clean the dirty flag and we must
577 * do it under the buffer lock to be sure we don't race
578 * with running write-out.
579 */
580 JBUFFER_TRACE(jh, "Journalling dirty buffer");
581 clear_buffer_dirty(bh);
582 set_buffer_jbddirty(bh);
583 }
584
585 unlock_buffer(bh);
586
587 error = -EROFS;
588 if (is_handle_aborted(handle)) {
589 jbd_unlock_bh_state(bh);
590 goto out;
591 }
592 error = 0;
593
594 /*
595 * The buffer is already part of this transaction if b_transaction or
596 * b_next_transaction points to it
597 */
598 if (jh->b_transaction == transaction ||
599 jh->b_next_transaction == transaction)
600 goto done;
601
602 /*
603 * this is the first time this transaction is touching this buffer,
604 * reset the modified flag
605 */
606 jh->b_modified = 0;
607
608 /*
609 * If there is already a copy-out version of this buffer, then we don't
610 * need to make another one
611 */
612 if (jh->b_frozen_data) {
613 JBUFFER_TRACE(jh, "has frozen data");
614 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
615 jh->b_next_transaction = transaction;
616 goto done;
617 }
618
619 /* Is there data here we need to preserve? */
620
621 if (jh->b_transaction && jh->b_transaction != transaction) {
622 JBUFFER_TRACE(jh, "owned by older transaction");
623 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
624 J_ASSERT_JH(jh, jh->b_transaction ==
625 journal->j_committing_transaction);
626
627 /* There is one case we have to be very careful about.
628 * If the committing transaction is currently writing
629 * this buffer out to disk and has NOT made a copy-out,
630 * then we cannot modify the buffer contents at all
631 * right now. The essence of copy-out is that it is the
632 * extra copy, not the primary copy, which gets
633 * journaled. If the primary copy is already going to
634 * disk then we cannot do copy-out here. */
635
636 if (jh->b_jlist == BJ_Shadow) {
637 DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
638 wait_queue_head_t *wqh;
639
640 wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
641
642 JBUFFER_TRACE(jh, "on shadow: sleep");
643 jbd_unlock_bh_state(bh);
644 /* commit wakes up all shadow buffers after IO */
645 for ( ; ; ) {
646 prepare_to_wait(wqh, &wait.wait,
647 TASK_UNINTERRUPTIBLE);
648 if (jh->b_jlist != BJ_Shadow)
649 break;
650 schedule();
651 }
652 finish_wait(wqh, &wait.wait);
653 goto repeat;
654 }
655
656 /* Only do the copy if the currently-owning transaction
657 * still needs it. If it is on the Forget list, the
658 * committing transaction is past that stage. The
659 * buffer had better remain locked during the kmalloc,
660 * but that should be true --- we hold the journal lock
661 * still and the buffer is already on the BUF_JOURNAL
662 * list so won't be flushed.
663 *
664 * Subtle point, though: if this is a get_undo_access,
665 * then we will be relying on the frozen_data to contain
666 * the new value of the committed_data record after the
667 * transaction, so we HAVE to force the frozen_data copy
668 * in that case. */
669
670 if (jh->b_jlist != BJ_Forget || force_copy) {
671 JBUFFER_TRACE(jh, "generate frozen data");
672 if (!frozen_buffer) {
673 JBUFFER_TRACE(jh, "allocate memory for buffer");
674 jbd_unlock_bh_state(bh);
675 frozen_buffer =
676 jbd_alloc(jh2bh(jh)->b_size,
677 GFP_NOFS);
678 if (!frozen_buffer) {
679 printk(KERN_EMERG
680 "%s: OOM for frozen_buffer\n",
681 __func__);
682 JBUFFER_TRACE(jh, "oom!");
683 error = -ENOMEM;
684 jbd_lock_bh_state(bh);
685 goto done;
686 }
687 goto repeat;
688 }
689 jh->b_frozen_data = frozen_buffer;
690 frozen_buffer = NULL;
691 need_copy = 1;
692 }
693 jh->b_next_transaction = transaction;
694 }
695
696
697 /*
698 * Finally, if the buffer is not journaled right now, we need to make
699 * sure it doesn't get written to disk before the caller actually
700 * commits the new data
701 */
702 if (!jh->b_transaction) {
703 JBUFFER_TRACE(jh, "no transaction");
704 J_ASSERT_JH(jh, !jh->b_next_transaction);
705 JBUFFER_TRACE(jh, "file as BJ_Reserved");
706 spin_lock(&journal->j_list_lock);
707 __journal_file_buffer(jh, transaction, BJ_Reserved);
708 spin_unlock(&journal->j_list_lock);
709 }
710
711done:
712 if (need_copy) {
713 struct page *page;
714 int offset;
715 char *source;
716
717 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
718 "Possible IO failure.\n");
719 page = jh2bh(jh)->b_page;
720 offset = offset_in_page(jh2bh(jh)->b_data);
721 source = kmap_atomic(page);
722 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
723 kunmap_atomic(source);
724 }
725 jbd_unlock_bh_state(bh);
726
727 /*
728 * If we are about to journal a buffer, then any revoke pending on it is
729 * no longer valid
730 */
731 journal_cancel_revoke(handle, jh);
732
733out:
734 if (unlikely(frozen_buffer)) /* It's usually NULL */
735 jbd_free(frozen_buffer, bh->b_size);
736
737 JBUFFER_TRACE(jh, "exit");
738 return error;
739}
740
741/**
742 * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
743 * @handle: transaction to add buffer modifications to
744 * @bh: bh to be used for metadata writes
745 *
746 * Returns an error code or 0 on success.
747 *
748 * In full data journalling mode the buffer may be of type BJ_AsyncData,
749 * because we're write()ing a buffer which is also part of a shared mapping.
750 */
751
752int journal_get_write_access(handle_t *handle, struct buffer_head *bh)
753{
754 struct journal_head *jh = journal_add_journal_head(bh);
755 int rc;
756
757 /* We do not want to get caught playing with fields which the
758 * log thread also manipulates. Make sure that the buffer
759 * completes any outstanding IO before proceeding. */
760 rc = do_get_write_access(handle, jh, 0);
761 journal_put_journal_head(jh);
762 return rc;
763}
764
765
766/*
767 * When the user wants to journal a newly created buffer_head
768 * (ie. getblk() returned a new buffer and we are going to populate it
769 * manually rather than reading off disk), then we need to keep the
770 * buffer_head locked until it has been completely filled with new
771 * data. In this case, we should be able to make the assertion that
772 * the bh is not already part of an existing transaction.
773 *
774 * The buffer should already be locked by the caller by this point.
775 * There is no lock ranking violation: it was a newly created,
776 * unlocked buffer beforehand. */
777
778/**
779 * int journal_get_create_access () - notify intent to use newly created bh
780 * @handle: transaction to new buffer to
781 * @bh: new buffer.
782 *
783 * Call this if you create a new bh.
784 */
785int journal_get_create_access(handle_t *handle, struct buffer_head *bh)
786{
787 transaction_t *transaction = handle->h_transaction;
788 journal_t *journal = transaction->t_journal;
789 struct journal_head *jh = journal_add_journal_head(bh);
790 int err;
791
792 jbd_debug(5, "journal_head %p\n", jh);
793 err = -EROFS;
794 if (is_handle_aborted(handle))
795 goto out;
796 err = 0;
797
798 JBUFFER_TRACE(jh, "entry");
799 /*
800 * The buffer may already belong to this transaction due to pre-zeroing
801 * in the filesystem's new_block code. It may also be on the previous,
802 * committing transaction's lists, but it HAS to be in Forget state in
803 * that case: the transaction must have deleted the buffer for it to be
804 * reused here.
805 */
806 jbd_lock_bh_state(bh);
807 spin_lock(&journal->j_list_lock);
808 J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
809 jh->b_transaction == NULL ||
810 (jh->b_transaction == journal->j_committing_transaction &&
811 jh->b_jlist == BJ_Forget)));
812
813 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
814 J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
815
816 if (jh->b_transaction == NULL) {
817 /*
818 * Previous journal_forget() could have left the buffer
819 * with jbddirty bit set because it was being committed. When
820 * the commit finished, we've filed the buffer for
821 * checkpointing and marked it dirty. Now we are reallocating
822 * the buffer so the transaction freeing it must have
823 * committed and so it's safe to clear the dirty bit.
824 */
825 clear_buffer_dirty(jh2bh(jh));
826
827 /* first access by this transaction */
828 jh->b_modified = 0;
829
830 JBUFFER_TRACE(jh, "file as BJ_Reserved");
831 __journal_file_buffer(jh, transaction, BJ_Reserved);
832 } else if (jh->b_transaction == journal->j_committing_transaction) {
833 /* first access by this transaction */
834 jh->b_modified = 0;
835
836 JBUFFER_TRACE(jh, "set next transaction");
837 jh->b_next_transaction = transaction;
838 }
839 spin_unlock(&journal->j_list_lock);
840 jbd_unlock_bh_state(bh);
841
842 /*
843 * akpm: I added this. ext3_alloc_branch can pick up new indirect
844 * blocks which contain freed but then revoked metadata. We need
845 * to cancel the revoke in case we end up freeing it yet again
846 * and the reallocating as data - this would cause a second revoke,
847 * which hits an assertion error.
848 */
849 JBUFFER_TRACE(jh, "cancelling revoke");
850 journal_cancel_revoke(handle, jh);
851out:
852 journal_put_journal_head(jh);
853 return err;
854}
855
856/**
857 * int journal_get_undo_access() - Notify intent to modify metadata with non-rewindable consequences
858 * @handle: transaction
859 * @bh: buffer to undo
860 *
861 * Sometimes there is a need to distinguish between metadata which has
862 * been committed to disk and that which has not. The ext3fs code uses
863 * this for freeing and allocating space, we have to make sure that we
864 * do not reuse freed space until the deallocation has been committed,
865 * since if we overwrote that space we would make the delete
866 * un-rewindable in case of a crash.
867 *
868 * To deal with that, journal_get_undo_access requests write access to a
869 * buffer for parts of non-rewindable operations such as delete
870 * operations on the bitmaps. The journaling code must keep a copy of
871 * the buffer's contents prior to the undo_access call until such time
872 * as we know that the buffer has definitely been committed to disk.
873 *
874 * We never need to know which transaction the committed data is part
875 * of, buffers touched here are guaranteed to be dirtied later and so
876 * will be committed to a new transaction in due course, at which point
877 * we can discard the old committed data pointer.
878 *
879 * Returns error number or 0 on success.
880 */
881int journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
882{
883 int err;
884 struct journal_head *jh = journal_add_journal_head(bh);
885 char *committed_data = NULL;
886
887 JBUFFER_TRACE(jh, "entry");
888
889 /*
890 * Do this first --- it can drop the journal lock, so we want to
891 * make sure that obtaining the committed_data is done
892 * atomically wrt. completion of any outstanding commits.
893 */
894 err = do_get_write_access(handle, jh, 1);
895 if (err)
896 goto out;
897
898repeat:
899 if (!jh->b_committed_data) {
900 committed_data = jbd_alloc(jh2bh(jh)->b_size, GFP_NOFS);
901 if (!committed_data) {
902 printk(KERN_EMERG "%s: No memory for committed data\n",
903 __func__);
904 err = -ENOMEM;
905 goto out;
906 }
907 }
908
909 jbd_lock_bh_state(bh);
910 if (!jh->b_committed_data) {
911 /* Copy out the current buffer contents into the
912 * preserved, committed copy. */
913 JBUFFER_TRACE(jh, "generate b_committed data");
914 if (!committed_data) {
915 jbd_unlock_bh_state(bh);
916 goto repeat;
917 }
918
919 jh->b_committed_data = committed_data;
920 committed_data = NULL;
921 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
922 }
923 jbd_unlock_bh_state(bh);
924out:
925 journal_put_journal_head(jh);
926 if (unlikely(committed_data))
927 jbd_free(committed_data, bh->b_size);
928 return err;
929}
930
931/**
932 * int journal_dirty_data() - mark a buffer as containing dirty data to be flushed
933 * @handle: transaction
934 * @bh: bufferhead to mark
935 *
936 * Description:
937 * Mark a buffer as containing dirty data which needs to be flushed before
938 * we can commit the current transaction.
939 *
940 * The buffer is placed on the transaction's data list and is marked as
941 * belonging to the transaction.
942 *
943 * Returns error number or 0 on success.
944 *
945 * journal_dirty_data() can be called via page_launder->ext3_writepage
946 * by kswapd.
947 */
948int journal_dirty_data(handle_t *handle, struct buffer_head *bh)
949{
950 journal_t *journal = handle->h_transaction->t_journal;
951 int need_brelse = 0;
952 struct journal_head *jh;
953 int ret = 0;
954
955 if (is_handle_aborted(handle))
956 return ret;
957
958 jh = journal_add_journal_head(bh);
959 JBUFFER_TRACE(jh, "entry");
960
961 /*
962 * The buffer could *already* be dirty. Writeout can start
963 * at any time.
964 */
965 jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
966
967 /*
968 * What if the buffer is already part of a running transaction?
969 *
970 * There are two cases:
971 * 1) It is part of the current running transaction. Refile it,
972 * just in case we have allocated it as metadata, deallocated
973 * it, then reallocated it as data.
974 * 2) It is part of the previous, still-committing transaction.
975 * If all we want to do is to guarantee that the buffer will be
976 * written to disk before this new transaction commits, then
977 * being sure that the *previous* transaction has this same
978 * property is sufficient for us! Just leave it on its old
979 * transaction.
980 *
981 * In case (2), the buffer must not already exist as metadata
982 * --- that would violate write ordering (a transaction is free
983 * to write its data at any point, even before the previous
984 * committing transaction has committed). The caller must
985 * never, ever allow this to happen: there's nothing we can do
986 * about it in this layer.
987 */
988 jbd_lock_bh_state(bh);
989 spin_lock(&journal->j_list_lock);
990
991 /* Now that we have bh_state locked, are we really still mapped? */
992 if (!buffer_mapped(bh)) {
993 JBUFFER_TRACE(jh, "unmapped buffer, bailing out");
994 goto no_journal;
995 }
996
997 if (jh->b_transaction) {
998 JBUFFER_TRACE(jh, "has transaction");
999 if (jh->b_transaction != handle->h_transaction) {
1000 JBUFFER_TRACE(jh, "belongs to older transaction");
1001 J_ASSERT_JH(jh, jh->b_transaction ==
1002 journal->j_committing_transaction);
1003
1004 /* @@@ IS THIS TRUE ? */
1005 /*
1006 * Not any more. Scenario: someone does a write()
1007 * in data=journal mode. The buffer's transaction has
1008 * moved into commit. Then someone does another
1009 * write() to the file. We do the frozen data copyout
1010 * and set b_next_transaction to point to j_running_t.
1011 * And while we're in that state, someone does a
1012 * writepage() in an attempt to pageout the same area
1013 * of the file via a shared mapping. At present that
1014 * calls journal_dirty_data(), and we get right here.
1015 * It may be too late to journal the data. Simply
1016 * falling through to the next test will suffice: the
1017 * data will be dirty and wil be checkpointed. The
1018 * ordering comments in the next comment block still
1019 * apply.
1020 */
1021 //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1022
1023 /*
1024 * If we're journalling data, and this buffer was
1025 * subject to a write(), it could be metadata, forget
1026 * or shadow against the committing transaction. Now,
1027 * someone has dirtied the same darn page via a mapping
1028 * and it is being writepage()'d.
1029 * We *could* just steal the page from commit, with some
1030 * fancy locking there. Instead, we just skip it -
1031 * don't tie the page's buffers to the new transaction
1032 * at all.
1033 * Implication: if we crash before the writepage() data
1034 * is written into the filesystem, recovery will replay
1035 * the write() data.
1036 */
1037 if (jh->b_jlist != BJ_None &&
1038 jh->b_jlist != BJ_SyncData &&
1039 jh->b_jlist != BJ_Locked) {
1040 JBUFFER_TRACE(jh, "Not stealing");
1041 goto no_journal;
1042 }
1043
1044 /*
1045 * This buffer may be undergoing writeout in commit. We
1046 * can't return from here and let the caller dirty it
1047 * again because that can cause the write-out loop in
1048 * commit to never terminate.
1049 */
1050 if (buffer_dirty(bh)) {
1051 get_bh(bh);
1052 spin_unlock(&journal->j_list_lock);
1053 jbd_unlock_bh_state(bh);
1054 need_brelse = 1;
1055 sync_dirty_buffer(bh);
1056 jbd_lock_bh_state(bh);
1057 spin_lock(&journal->j_list_lock);
1058 /* Since we dropped the lock... */
1059 if (!buffer_mapped(bh)) {
1060 JBUFFER_TRACE(jh, "buffer got unmapped");
1061 goto no_journal;
1062 }
1063 /* The buffer may become locked again at any
1064 time if it is redirtied */
1065 }
1066
1067 /*
1068 * We cannot remove the buffer with io error from the
1069 * committing transaction, because otherwise it would
1070 * miss the error and the commit would not abort.
1071 */
1072 if (unlikely(!buffer_uptodate(bh))) {
1073 ret = -EIO;
1074 goto no_journal;
1075 }
1076 /* We might have slept so buffer could be refiled now */
1077 if (jh->b_transaction != NULL &&
1078 jh->b_transaction != handle->h_transaction) {
1079 JBUFFER_TRACE(jh, "unfile from commit");
1080 __journal_temp_unlink_buffer(jh);
1081 /* It still points to the committing
1082 * transaction; move it to this one so
1083 * that the refile assert checks are
1084 * happy. */
1085 jh->b_transaction = handle->h_transaction;
1086 }
1087 /* The buffer will be refiled below */
1088
1089 }
1090 /*
1091 * Special case --- the buffer might actually have been
1092 * allocated and then immediately deallocated in the previous,
1093 * committing transaction, so might still be left on that
1094 * transaction's metadata lists.
1095 */
1096 if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
1097 JBUFFER_TRACE(jh, "not on correct data list: unfile");
1098 J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
1099 JBUFFER_TRACE(jh, "file as data");
1100 __journal_file_buffer(jh, handle->h_transaction,
1101 BJ_SyncData);
1102 }
1103 } else {
1104 JBUFFER_TRACE(jh, "not on a transaction");
1105 __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
1106 }
1107no_journal:
1108 spin_unlock(&journal->j_list_lock);
1109 jbd_unlock_bh_state(bh);
1110 if (need_brelse) {
1111 BUFFER_TRACE(bh, "brelse");
1112 __brelse(bh);
1113 }
1114 JBUFFER_TRACE(jh, "exit");
1115 journal_put_journal_head(jh);
1116 return ret;
1117}
1118
1119/**
1120 * int journal_dirty_metadata() - mark a buffer as containing dirty metadata
1121 * @handle: transaction to add buffer to.
1122 * @bh: buffer to mark
1123 *
1124 * Mark dirty metadata which needs to be journaled as part of the current
1125 * transaction.
1126 *
1127 * The buffer is placed on the transaction's metadata list and is marked
1128 * as belonging to the transaction.
1129 *
1130 * Returns error number or 0 on success.
1131 *
1132 * Special care needs to be taken if the buffer already belongs to the
1133 * current committing transaction (in which case we should have frozen
1134 * data present for that commit). In that case, we don't relink the
1135 * buffer: that only gets done when the old transaction finally
1136 * completes its commit.
1137 */
1138int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1139{
1140 transaction_t *transaction = handle->h_transaction;
1141 journal_t *journal = transaction->t_journal;
1142 struct journal_head *jh = bh2jh(bh);
1143
1144 jbd_debug(5, "journal_head %p\n", jh);
1145 JBUFFER_TRACE(jh, "entry");
1146 if (is_handle_aborted(handle))
1147 goto out;
1148
1149 jbd_lock_bh_state(bh);
1150
1151 if (jh->b_modified == 0) {
1152 /*
1153 * This buffer's got modified and becoming part
1154 * of the transaction. This needs to be done
1155 * once a transaction -bzzz
1156 */
1157 jh->b_modified = 1;
1158 J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
1159 handle->h_buffer_credits--;
1160 }
1161
1162 /*
1163 * fastpath, to avoid expensive locking. If this buffer is already
1164 * on the running transaction's metadata list there is nothing to do.
1165 * Nobody can take it off again because there is a handle open.
1166 * I _think_ we're OK here with SMP barriers - a mistaken decision will
1167 * result in this test being false, so we go in and take the locks.
1168 */
1169 if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1170 JBUFFER_TRACE(jh, "fastpath");
1171 J_ASSERT_JH(jh, jh->b_transaction ==
1172 journal->j_running_transaction);
1173 goto out_unlock_bh;
1174 }
1175
1176 set_buffer_jbddirty(bh);
1177
1178 /*
1179 * Metadata already on the current transaction list doesn't
1180 * need to be filed. Metadata on another transaction's list must
1181 * be committing, and will be refiled once the commit completes:
1182 * leave it alone for now.
1183 */
1184 if (jh->b_transaction != transaction) {
1185 JBUFFER_TRACE(jh, "already on other transaction");
1186 J_ASSERT_JH(jh, jh->b_transaction ==
1187 journal->j_committing_transaction);
1188 J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
1189 /* And this case is illegal: we can't reuse another
1190 * transaction's data buffer, ever. */
1191 goto out_unlock_bh;
1192 }
1193
1194 /* That test should have eliminated the following case: */
1195 J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
1196
1197 JBUFFER_TRACE(jh, "file as BJ_Metadata");
1198 spin_lock(&journal->j_list_lock);
1199 __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1200 spin_unlock(&journal->j_list_lock);
1201out_unlock_bh:
1202 jbd_unlock_bh_state(bh);
1203out:
1204 JBUFFER_TRACE(jh, "exit");
1205 return 0;
1206}
1207
1208/*
1209 * journal_release_buffer: undo a get_write_access without any buffer
1210 * updates, if the update decided in the end that it didn't need access.
1211 *
1212 */
1213void
1214journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1215{
1216 BUFFER_TRACE(bh, "entry");
1217}
1218
1219/**
1220 * void journal_forget() - bforget() for potentially-journaled buffers.
1221 * @handle: transaction handle
1222 * @bh: bh to 'forget'
1223 *
1224 * We can only do the bforget if there are no commits pending against the
1225 * buffer. If the buffer is dirty in the current running transaction we
1226 * can safely unlink it.
1227 *
1228 * bh may not be a journalled buffer at all - it may be a non-JBD
1229 * buffer which came off the hashtable. Check for this.
1230 *
1231 * Decrements bh->b_count by one.
1232 *
1233 * Allow this call even if the handle has aborted --- it may be part of
1234 * the caller's cleanup after an abort.
1235 */
1236int journal_forget (handle_t *handle, struct buffer_head *bh)
1237{
1238 transaction_t *transaction = handle->h_transaction;
1239 journal_t *journal = transaction->t_journal;
1240 struct journal_head *jh;
1241 int drop_reserve = 0;
1242 int err = 0;
1243 int was_modified = 0;
1244
1245 BUFFER_TRACE(bh, "entry");
1246
1247 jbd_lock_bh_state(bh);
1248 spin_lock(&journal->j_list_lock);
1249
1250 if (!buffer_jbd(bh))
1251 goto not_jbd;
1252 jh = bh2jh(bh);
1253
1254 /* Critical error: attempting to delete a bitmap buffer, maybe?
1255 * Don't do any jbd operations, and return an error. */
1256 if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1257 "inconsistent data on disk")) {
1258 err = -EIO;
1259 goto not_jbd;
1260 }
1261
1262 /* keep track of wether or not this transaction modified us */
1263 was_modified = jh->b_modified;
1264
1265 /*
1266 * The buffer's going from the transaction, we must drop
1267 * all references -bzzz
1268 */
1269 jh->b_modified = 0;
1270
1271 if (jh->b_transaction == handle->h_transaction) {
1272 J_ASSERT_JH(jh, !jh->b_frozen_data);
1273
1274 /* If we are forgetting a buffer which is already part
1275 * of this transaction, then we can just drop it from
1276 * the transaction immediately. */
1277 clear_buffer_dirty(bh);
1278 clear_buffer_jbddirty(bh);
1279
1280 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1281
1282 /*
1283 * we only want to drop a reference if this transaction
1284 * modified the buffer
1285 */
1286 if (was_modified)
1287 drop_reserve = 1;
1288
1289 /*
1290 * We are no longer going to journal this buffer.
1291 * However, the commit of this transaction is still
1292 * important to the buffer: the delete that we are now
1293 * processing might obsolete an old log entry, so by
1294 * committing, we can satisfy the buffer's checkpoint.
1295 *
1296 * So, if we have a checkpoint on the buffer, we should
1297 * now refile the buffer on our BJ_Forget list so that
1298 * we know to remove the checkpoint after we commit.
1299 */
1300
1301 if (jh->b_cp_transaction) {
1302 __journal_temp_unlink_buffer(jh);
1303 __journal_file_buffer(jh, transaction, BJ_Forget);
1304 } else {
1305 __journal_unfile_buffer(jh);
1306 if (!buffer_jbd(bh)) {
1307 spin_unlock(&journal->j_list_lock);
1308 jbd_unlock_bh_state(bh);
1309 __bforget(bh);
1310 goto drop;
1311 }
1312 }
1313 } else if (jh->b_transaction) {
1314 J_ASSERT_JH(jh, (jh->b_transaction ==
1315 journal->j_committing_transaction));
1316 /* However, if the buffer is still owned by a prior
1317 * (committing) transaction, we can't drop it yet... */
1318 JBUFFER_TRACE(jh, "belongs to older transaction");
1319 /* ... but we CAN drop it from the new transaction if we
1320 * have also modified it since the original commit. */
1321
1322 if (jh->b_next_transaction) {
1323 J_ASSERT(jh->b_next_transaction == transaction);
1324 jh->b_next_transaction = NULL;
1325
1326 /*
1327 * only drop a reference if this transaction modified
1328 * the buffer
1329 */
1330 if (was_modified)
1331 drop_reserve = 1;
1332 }
1333 }
1334
1335not_jbd:
1336 spin_unlock(&journal->j_list_lock);
1337 jbd_unlock_bh_state(bh);
1338 __brelse(bh);
1339drop:
1340 if (drop_reserve) {
1341 /* no need to reserve log space for this block -bzzz */
1342 handle->h_buffer_credits++;
1343 }
1344 return err;
1345}
1346
1347/**
1348 * int journal_stop() - complete a transaction
1349 * @handle: tranaction to complete.
1350 *
1351 * All done for a particular handle.
1352 *
1353 * There is not much action needed here. We just return any remaining
1354 * buffer credits to the transaction and remove the handle. The only
1355 * complication is that we need to start a commit operation if the
1356 * filesystem is marked for synchronous update.
1357 *
1358 * journal_stop itself will not usually return an error, but it may
1359 * do so in unusual circumstances. In particular, expect it to
1360 * return -EIO if a journal_abort has been executed since the
1361 * transaction began.
1362 */
1363int journal_stop(handle_t *handle)
1364{
1365 transaction_t *transaction = handle->h_transaction;
1366 journal_t *journal = transaction->t_journal;
1367 int err;
1368 pid_t pid;
1369
1370 J_ASSERT(journal_current_handle() == handle);
1371
1372 if (is_handle_aborted(handle))
1373 err = -EIO;
1374 else {
1375 J_ASSERT(transaction->t_updates > 0);
1376 err = 0;
1377 }
1378
1379 if (--handle->h_ref > 0) {
1380 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1381 handle->h_ref);
1382 return err;
1383 }
1384
1385 jbd_debug(4, "Handle %p going down\n", handle);
1386
1387 /*
1388 * Implement synchronous transaction batching. If the handle
1389 * was synchronous, don't force a commit immediately. Let's
1390 * yield and let another thread piggyback onto this transaction.
1391 * Keep doing that while new threads continue to arrive.
1392 * It doesn't cost much - we're about to run a commit and sleep
1393 * on IO anyway. Speeds up many-threaded, many-dir operations
1394 * by 30x or more...
1395 *
1396 * We try and optimize the sleep time against what the underlying disk
1397 * can do, instead of having a static sleep time. This is useful for
1398 * the case where our storage is so fast that it is more optimal to go
1399 * ahead and force a flush and wait for the transaction to be committed
1400 * than it is to wait for an arbitrary amount of time for new writers to
1401 * join the transaction. We achieve this by measuring how long it takes
1402 * to commit a transaction, and compare it with how long this
1403 * transaction has been running, and if run time < commit time then we
1404 * sleep for the delta and commit. This greatly helps super fast disks
1405 * that would see slowdowns as more threads started doing fsyncs.
1406 *
1407 * But don't do this if this process was the most recent one to
1408 * perform a synchronous write. We do this to detect the case where a
1409 * single process is doing a stream of sync writes. No point in waiting
1410 * for joiners in that case.
1411 */
1412 pid = current->pid;
1413 if (handle->h_sync && journal->j_last_sync_writer != pid) {
1414 u64 commit_time, trans_time;
1415
1416 journal->j_last_sync_writer = pid;
1417
1418 spin_lock(&journal->j_state_lock);
1419 commit_time = journal->j_average_commit_time;
1420 spin_unlock(&journal->j_state_lock);
1421
1422 trans_time = ktime_to_ns(ktime_sub(ktime_get(),
1423 transaction->t_start_time));
1424
1425 commit_time = min_t(u64, commit_time,
1426 1000*jiffies_to_usecs(1));
1427
1428 if (trans_time < commit_time) {
1429 ktime_t expires = ktime_add_ns(ktime_get(),
1430 commit_time);
1431 set_current_state(TASK_UNINTERRUPTIBLE);
1432 schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
1433 }
1434 }
1435
1436 current->journal_info = NULL;
1437 spin_lock(&journal->j_state_lock);
1438 spin_lock(&transaction->t_handle_lock);
1439 transaction->t_outstanding_credits -= handle->h_buffer_credits;
1440 transaction->t_updates--;
1441 if (!transaction->t_updates) {
1442 wake_up(&journal->j_wait_updates);
1443 if (journal->j_barrier_count)
1444 wake_up(&journal->j_wait_transaction_locked);
1445 }
1446
1447 /*
1448 * If the handle is marked SYNC, we need to set another commit
1449 * going! We also want to force a commit if the current
1450 * transaction is occupying too much of the log, or if the
1451 * transaction is too old now.
1452 */
1453 if (handle->h_sync ||
1454 transaction->t_outstanding_credits >
1455 journal->j_max_transaction_buffers ||
1456 time_after_eq(jiffies, transaction->t_expires)) {
1457 /* Do this even for aborted journals: an abort still
1458 * completes the commit thread, it just doesn't write
1459 * anything to disk. */
1460 tid_t tid = transaction->t_tid;
1461
1462 spin_unlock(&transaction->t_handle_lock);
1463 jbd_debug(2, "transaction too old, requesting commit for "
1464 "handle %p\n", handle);
1465 /* This is non-blocking */
1466 __log_start_commit(journal, transaction->t_tid);
1467 spin_unlock(&journal->j_state_lock);
1468
1469 /*
1470 * Special case: JFS_SYNC synchronous updates require us
1471 * to wait for the commit to complete.
1472 */
1473 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1474 err = log_wait_commit(journal, tid);
1475 } else {
1476 spin_unlock(&transaction->t_handle_lock);
1477 spin_unlock(&journal->j_state_lock);
1478 }
1479
1480 lock_map_release(&handle->h_lockdep_map);
1481
1482 jbd_free_handle(handle);
1483 return err;
1484}
1485
1486/**
1487 * int journal_force_commit() - force any uncommitted transactions
1488 * @journal: journal to force
1489 *
1490 * For synchronous operations: force any uncommitted transactions
1491 * to disk. May seem kludgy, but it reuses all the handle batching
1492 * code in a very simple manner.
1493 */
1494int journal_force_commit(journal_t *journal)
1495{
1496 handle_t *handle;
1497 int ret;
1498
1499 handle = journal_start(journal, 1);
1500 if (IS_ERR(handle)) {
1501 ret = PTR_ERR(handle);
1502 } else {
1503 handle->h_sync = 1;
1504 ret = journal_stop(handle);
1505 }
1506 return ret;
1507}
1508
1509/*
1510 *
1511 * List management code snippets: various functions for manipulating the
1512 * transaction buffer lists.
1513 *
1514 */
1515
1516/*
1517 * Append a buffer to a transaction list, given the transaction's list head
1518 * pointer.
1519 *
1520 * j_list_lock is held.
1521 *
1522 * jbd_lock_bh_state(jh2bh(jh)) is held.
1523 */
1524
1525static inline void
1526__blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1527{
1528 if (!*list) {
1529 jh->b_tnext = jh->b_tprev = jh;
1530 *list = jh;
1531 } else {
1532 /* Insert at the tail of the list to preserve order */
1533 struct journal_head *first = *list, *last = first->b_tprev;
1534 jh->b_tprev = last;
1535 jh->b_tnext = first;
1536 last->b_tnext = first->b_tprev = jh;
1537 }
1538}
1539
1540/*
1541 * Remove a buffer from a transaction list, given the transaction's list
1542 * head pointer.
1543 *
1544 * Called with j_list_lock held, and the journal may not be locked.
1545 *
1546 * jbd_lock_bh_state(jh2bh(jh)) is held.
1547 */
1548
1549static inline void
1550__blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1551{
1552 if (*list == jh) {
1553 *list = jh->b_tnext;
1554 if (*list == jh)
1555 *list = NULL;
1556 }
1557 jh->b_tprev->b_tnext = jh->b_tnext;
1558 jh->b_tnext->b_tprev = jh->b_tprev;
1559}
1560
1561/*
1562 * Remove a buffer from the appropriate transaction list.
1563 *
1564 * Note that this function can *change* the value of
1565 * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
1566 * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller
1567 * is holding onto a copy of one of thee pointers, it could go bad.
1568 * Generally the caller needs to re-read the pointer from the transaction_t.
1569 *
1570 * Called under j_list_lock. The journal may not be locked.
1571 */
1572static void __journal_temp_unlink_buffer(struct journal_head *jh)
1573{
1574 struct journal_head **list = NULL;
1575 transaction_t *transaction;
1576 struct buffer_head *bh = jh2bh(jh);
1577
1578 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1579 transaction = jh->b_transaction;
1580 if (transaction)
1581 assert_spin_locked(&transaction->t_journal->j_list_lock);
1582
1583 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1584 if (jh->b_jlist != BJ_None)
1585 J_ASSERT_JH(jh, transaction != NULL);
1586
1587 switch (jh->b_jlist) {
1588 case BJ_None:
1589 return;
1590 case BJ_SyncData:
1591 list = &transaction->t_sync_datalist;
1592 break;
1593 case BJ_Metadata:
1594 transaction->t_nr_buffers--;
1595 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1596 list = &transaction->t_buffers;
1597 break;
1598 case BJ_Forget:
1599 list = &transaction->t_forget;
1600 break;
1601 case BJ_IO:
1602 list = &transaction->t_iobuf_list;
1603 break;
1604 case BJ_Shadow:
1605 list = &transaction->t_shadow_list;
1606 break;
1607 case BJ_LogCtl:
1608 list = &transaction->t_log_list;
1609 break;
1610 case BJ_Reserved:
1611 list = &transaction->t_reserved_list;
1612 break;
1613 case BJ_Locked:
1614 list = &transaction->t_locked_list;
1615 break;
1616 }
1617
1618 __blist_del_buffer(list, jh);
1619 jh->b_jlist = BJ_None;
1620 if (test_clear_buffer_jbddirty(bh))
1621 mark_buffer_dirty(bh); /* Expose it to the VM */
1622}
1623
1624/*
1625 * Remove buffer from all transactions.
1626 *
1627 * Called with bh_state lock and j_list_lock
1628 *
1629 * jh and bh may be already freed when this function returns.
1630 */
1631void __journal_unfile_buffer(struct journal_head *jh)
1632{
1633 __journal_temp_unlink_buffer(jh);
1634 jh->b_transaction = NULL;
1635 journal_put_journal_head(jh);
1636}
1637
1638void journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1639{
1640 struct buffer_head *bh = jh2bh(jh);
1641
1642 /* Get reference so that buffer cannot be freed before we unlock it */
1643 get_bh(bh);
1644 jbd_lock_bh_state(bh);
1645 spin_lock(&journal->j_list_lock);
1646 __journal_unfile_buffer(jh);
1647 spin_unlock(&journal->j_list_lock);
1648 jbd_unlock_bh_state(bh);
1649 __brelse(bh);
1650}
1651
1652/*
1653 * Called from journal_try_to_free_buffers().
1654 *
1655 * Called under jbd_lock_bh_state(bh)
1656 */
1657static void
1658__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1659{
1660 struct journal_head *jh;
1661
1662 jh = bh2jh(bh);
1663
1664 if (buffer_locked(bh) || buffer_dirty(bh))
1665 goto out;
1666
1667 if (jh->b_next_transaction != NULL)
1668 goto out;
1669
1670 spin_lock(&journal->j_list_lock);
1671 if (jh->b_transaction != NULL && jh->b_cp_transaction == NULL) {
1672 if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
1673 /* A written-back ordered data buffer */
1674 JBUFFER_TRACE(jh, "release data");
1675 __journal_unfile_buffer(jh);
1676 }
1677 } else if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) {
1678 /* written-back checkpointed metadata buffer */
1679 if (jh->b_jlist == BJ_None) {
1680 JBUFFER_TRACE(jh, "remove from checkpoint list");
1681 __journal_remove_checkpoint(jh);
1682 }
1683 }
1684 spin_unlock(&journal->j_list_lock);
1685out:
1686 return;
1687}
1688
1689/**
1690 * int journal_try_to_free_buffers() - try to free page buffers.
1691 * @journal: journal for operation
1692 * @page: to try and free
1693 * @gfp_mask: we use the mask to detect how hard should we try to release
1694 * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to
1695 * release the buffers.
1696 *
1697 *
1698 * For all the buffers on this page,
1699 * if they are fully written out ordered data, move them onto BUF_CLEAN
1700 * so try_to_free_buffers() can reap them.
1701 *
1702 * This function returns non-zero if we wish try_to_free_buffers()
1703 * to be called. We do this if the page is releasable by try_to_free_buffers().
1704 * We also do it if the page has locked or dirty buffers and the caller wants
1705 * us to perform sync or async writeout.
1706 *
1707 * This complicates JBD locking somewhat. We aren't protected by the
1708 * BKL here. We wish to remove the buffer from its committing or
1709 * running transaction's ->t_datalist via __journal_unfile_buffer.
1710 *
1711 * This may *change* the value of transaction_t->t_datalist, so anyone
1712 * who looks at t_datalist needs to lock against this function.
1713 *
1714 * Even worse, someone may be doing a journal_dirty_data on this
1715 * buffer. So we need to lock against that. journal_dirty_data()
1716 * will come out of the lock with the buffer dirty, which makes it
1717 * ineligible for release here.
1718 *
1719 * Who else is affected by this? hmm... Really the only contender
1720 * is do_get_write_access() - it could be looking at the buffer while
1721 * journal_try_to_free_buffer() is changing its state. But that
1722 * cannot happen because we never reallocate freed data as metadata
1723 * while the data is part of a transaction. Yes?
1724 *
1725 * Return 0 on failure, 1 on success
1726 */
1727int journal_try_to_free_buffers(journal_t *journal,
1728 struct page *page, gfp_t gfp_mask)
1729{
1730 struct buffer_head *head;
1731 struct buffer_head *bh;
1732 int ret = 0;
1733
1734 J_ASSERT(PageLocked(page));
1735
1736 head = page_buffers(page);
1737 bh = head;
1738 do {
1739 struct journal_head *jh;
1740
1741 /*
1742 * We take our own ref against the journal_head here to avoid
1743 * having to add tons of locking around each instance of
1744 * journal_put_journal_head().
1745 */
1746 jh = journal_grab_journal_head(bh);
1747 if (!jh)
1748 continue;
1749
1750 jbd_lock_bh_state(bh);
1751 __journal_try_to_free_buffer(journal, bh);
1752 journal_put_journal_head(jh);
1753 jbd_unlock_bh_state(bh);
1754 if (buffer_jbd(bh))
1755 goto busy;
1756 } while ((bh = bh->b_this_page) != head);
1757
1758 ret = try_to_free_buffers(page);
1759
1760busy:
1761 return ret;
1762}
1763
1764/*
1765 * This buffer is no longer needed. If it is on an older transaction's
1766 * checkpoint list we need to record it on this transaction's forget list
1767 * to pin this buffer (and hence its checkpointing transaction) down until
1768 * this transaction commits. If the buffer isn't on a checkpoint list, we
1769 * release it.
1770 * Returns non-zero if JBD no longer has an interest in the buffer.
1771 *
1772 * Called under j_list_lock.
1773 *
1774 * Called under jbd_lock_bh_state(bh).
1775 */
1776static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1777{
1778 int may_free = 1;
1779 struct buffer_head *bh = jh2bh(jh);
1780
1781 if (jh->b_cp_transaction) {
1782 JBUFFER_TRACE(jh, "on running+cp transaction");
1783 __journal_temp_unlink_buffer(jh);
1784 /*
1785 * We don't want to write the buffer anymore, clear the
1786 * bit so that we don't confuse checks in
1787 * __journal_file_buffer
1788 */
1789 clear_buffer_dirty(bh);
1790 __journal_file_buffer(jh, transaction, BJ_Forget);
1791 may_free = 0;
1792 } else {
1793 JBUFFER_TRACE(jh, "on running transaction");
1794 __journal_unfile_buffer(jh);
1795 }
1796 return may_free;
1797}
1798
1799/*
1800 * journal_invalidatepage
1801 *
1802 * This code is tricky. It has a number of cases to deal with.
1803 *
1804 * There are two invariants which this code relies on:
1805 *
1806 * i_size must be updated on disk before we start calling invalidatepage on the
1807 * data.
1808 *
1809 * This is done in ext3 by defining an ext3_setattr method which
1810 * updates i_size before truncate gets going. By maintaining this
1811 * invariant, we can be sure that it is safe to throw away any buffers
1812 * attached to the current transaction: once the transaction commits,
1813 * we know that the data will not be needed.
1814 *
1815 * Note however that we can *not* throw away data belonging to the
1816 * previous, committing transaction!
1817 *
1818 * Any disk blocks which *are* part of the previous, committing
1819 * transaction (and which therefore cannot be discarded immediately) are
1820 * not going to be reused in the new running transaction
1821 *
1822 * The bitmap committed_data images guarantee this: any block which is
1823 * allocated in one transaction and removed in the next will be marked
1824 * as in-use in the committed_data bitmap, so cannot be reused until
1825 * the next transaction to delete the block commits. This means that
1826 * leaving committing buffers dirty is quite safe: the disk blocks
1827 * cannot be reallocated to a different file and so buffer aliasing is
1828 * not possible.
1829 *
1830 *
1831 * The above applies mainly to ordered data mode. In writeback mode we
1832 * don't make guarantees about the order in which data hits disk --- in
1833 * particular we don't guarantee that new dirty data is flushed before
1834 * transaction commit --- so it is always safe just to discard data
1835 * immediately in that mode. --sct
1836 */
1837
1838/*
1839 * The journal_unmap_buffer helper function returns zero if the buffer
1840 * concerned remains pinned as an anonymous buffer belonging to an older
1841 * transaction.
1842 *
1843 * We're outside-transaction here. Either or both of j_running_transaction
1844 * and j_committing_transaction may be NULL.
1845 */
1846static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1847{
1848 transaction_t *transaction;
1849 struct journal_head *jh;
1850 int may_free = 1;
1851 int ret;
1852
1853 BUFFER_TRACE(bh, "entry");
1854
1855 /*
1856 * It is safe to proceed here without the j_list_lock because the
1857 * buffers cannot be stolen by try_to_free_buffers as long as we are
1858 * holding the page lock. --sct
1859 */
1860
1861 if (!buffer_jbd(bh))
1862 goto zap_buffer_unlocked;
1863
1864 spin_lock(&journal->j_state_lock);
1865 jbd_lock_bh_state(bh);
1866 spin_lock(&journal->j_list_lock);
1867
1868 jh = journal_grab_journal_head(bh);
1869 if (!jh)
1870 goto zap_buffer_no_jh;
1871
1872 /*
1873 * We cannot remove the buffer from checkpoint lists until the
1874 * transaction adding inode to orphan list (let's call it T)
1875 * is committed. Otherwise if the transaction changing the
1876 * buffer would be cleaned from the journal before T is
1877 * committed, a crash will cause that the correct contents of
1878 * the buffer will be lost. On the other hand we have to
1879 * clear the buffer dirty bit at latest at the moment when the
1880 * transaction marking the buffer as freed in the filesystem
1881 * structures is committed because from that moment on the
1882 * buffer can be reallocated and used by a different page.
1883 * Since the block hasn't been freed yet but the inode has
1884 * already been added to orphan list, it is safe for us to add
1885 * the buffer to BJ_Forget list of the newest transaction.
1886 */
1887 transaction = jh->b_transaction;
1888 if (transaction == NULL) {
1889 /* First case: not on any transaction. If it
1890 * has no checkpoint link, then we can zap it:
1891 * it's a writeback-mode buffer so we don't care
1892 * if it hits disk safely. */
1893 if (!jh->b_cp_transaction) {
1894 JBUFFER_TRACE(jh, "not on any transaction: zap");
1895 goto zap_buffer;
1896 }
1897
1898 if (!buffer_dirty(bh)) {
1899 /* bdflush has written it. We can drop it now */
1900 goto zap_buffer;
1901 }
1902
1903 /* OK, it must be in the journal but still not
1904 * written fully to disk: it's metadata or
1905 * journaled data... */
1906
1907 if (journal->j_running_transaction) {
1908 /* ... and once the current transaction has
1909 * committed, the buffer won't be needed any
1910 * longer. */
1911 JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1912 ret = __dispose_buffer(jh,
1913 journal->j_running_transaction);
1914 journal_put_journal_head(jh);
1915 spin_unlock(&journal->j_list_lock);
1916 jbd_unlock_bh_state(bh);
1917 spin_unlock(&journal->j_state_lock);
1918 return ret;
1919 } else {
1920 /* There is no currently-running transaction. So the
1921 * orphan record which we wrote for this file must have
1922 * passed into commit. We must attach this buffer to
1923 * the committing transaction, if it exists. */
1924 if (journal->j_committing_transaction) {
1925 JBUFFER_TRACE(jh, "give to committing trans");
1926 ret = __dispose_buffer(jh,
1927 journal->j_committing_transaction);
1928 journal_put_journal_head(jh);
1929 spin_unlock(&journal->j_list_lock);
1930 jbd_unlock_bh_state(bh);
1931 spin_unlock(&journal->j_state_lock);
1932 return ret;
1933 } else {
1934 /* The orphan record's transaction has
1935 * committed. We can cleanse this buffer */
1936 clear_buffer_jbddirty(bh);
1937 goto zap_buffer;
1938 }
1939 }
1940 } else if (transaction == journal->j_committing_transaction) {
1941 JBUFFER_TRACE(jh, "on committing transaction");
1942 if (jh->b_jlist == BJ_Locked) {
1943 /*
1944 * The buffer is on the committing transaction's locked
1945 * list. We have the buffer locked, so I/O has
1946 * completed. So we can nail the buffer now.
1947 */
1948 may_free = __dispose_buffer(jh, transaction);
1949 goto zap_buffer;
1950 }
1951 /*
1952 * The buffer is committing, we simply cannot touch
1953 * it. So we just set j_next_transaction to the
1954 * running transaction (if there is one) and mark
1955 * buffer as freed so that commit code knows it should
1956 * clear dirty bits when it is done with the buffer.
1957 */
1958 set_buffer_freed(bh);
1959 if (journal->j_running_transaction && buffer_jbddirty(bh))
1960 jh->b_next_transaction = journal->j_running_transaction;
1961 journal_put_journal_head(jh);
1962 spin_unlock(&journal->j_list_lock);
1963 jbd_unlock_bh_state(bh);
1964 spin_unlock(&journal->j_state_lock);
1965 return 0;
1966 } else {
1967 /* Good, the buffer belongs to the running transaction.
1968 * We are writing our own transaction's data, not any
1969 * previous one's, so it is safe to throw it away
1970 * (remember that we expect the filesystem to have set
1971 * i_size already for this truncate so recovery will not
1972 * expose the disk blocks we are discarding here.) */
1973 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
1974 JBUFFER_TRACE(jh, "on running transaction");
1975 may_free = __dispose_buffer(jh, transaction);
1976 }
1977
1978zap_buffer:
1979 journal_put_journal_head(jh);
1980zap_buffer_no_jh:
1981 spin_unlock(&journal->j_list_lock);
1982 jbd_unlock_bh_state(bh);
1983 spin_unlock(&journal->j_state_lock);
1984zap_buffer_unlocked:
1985 clear_buffer_dirty(bh);
1986 J_ASSERT_BH(bh, !buffer_jbddirty(bh));
1987 clear_buffer_mapped(bh);
1988 clear_buffer_req(bh);
1989 clear_buffer_new(bh);
1990 bh->b_bdev = NULL;
1991 return may_free;
1992}
1993
1994/**
1995 * void journal_invalidatepage() - invalidate a journal page
1996 * @journal: journal to use for flush
1997 * @page: page to flush
1998 * @offset: length of page to invalidate.
1999 *
2000 * Reap page buffers containing data after offset in page.
2001 */
2002void journal_invalidatepage(journal_t *journal,
2003 struct page *page,
2004 unsigned long offset)
2005{
2006 struct buffer_head *head, *bh, *next;
2007 unsigned int curr_off = 0;
2008 int may_free = 1;
2009
2010 if (!PageLocked(page))
2011 BUG();
2012 if (!page_has_buffers(page))
2013 return;
2014
2015 /* We will potentially be playing with lists other than just the
2016 * data lists (especially for journaled data mode), so be
2017 * cautious in our locking. */
2018
2019 head = bh = page_buffers(page);
2020 do {
2021 unsigned int next_off = curr_off + bh->b_size;
2022 next = bh->b_this_page;
2023
2024 if (offset <= curr_off) {
2025 /* This block is wholly outside the truncation point */
2026 lock_buffer(bh);
2027 may_free &= journal_unmap_buffer(journal, bh);
2028 unlock_buffer(bh);
2029 }
2030 curr_off = next_off;
2031 bh = next;
2032
2033 } while (bh != head);
2034
2035 if (!offset) {
2036 if (may_free && try_to_free_buffers(page))
2037 J_ASSERT(!page_has_buffers(page));
2038 }
2039}
2040
2041/*
2042 * File a buffer on the given transaction list.
2043 */
2044void __journal_file_buffer(struct journal_head *jh,
2045 transaction_t *transaction, int jlist)
2046{
2047 struct journal_head **list = NULL;
2048 int was_dirty = 0;
2049 struct buffer_head *bh = jh2bh(jh);
2050
2051 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2052 assert_spin_locked(&transaction->t_journal->j_list_lock);
2053
2054 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
2055 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
2056 jh->b_transaction == NULL);
2057
2058 if (jh->b_transaction && jh->b_jlist == jlist)
2059 return;
2060
2061 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
2062 jlist == BJ_Shadow || jlist == BJ_Forget) {
2063 /*
2064 * For metadata buffers, we track dirty bit in buffer_jbddirty
2065 * instead of buffer_dirty. We should not see a dirty bit set
2066 * here because we clear it in do_get_write_access but e.g.
2067 * tune2fs can modify the sb and set the dirty bit at any time
2068 * so we try to gracefully handle that.
2069 */
2070 if (buffer_dirty(bh))
2071 warn_dirty_buffer(bh);
2072 if (test_clear_buffer_dirty(bh) ||
2073 test_clear_buffer_jbddirty(bh))
2074 was_dirty = 1;
2075 }
2076
2077 if (jh->b_transaction)
2078 __journal_temp_unlink_buffer(jh);
2079 else
2080 journal_grab_journal_head(bh);
2081 jh->b_transaction = transaction;
2082
2083 switch (jlist) {
2084 case BJ_None:
2085 J_ASSERT_JH(jh, !jh->b_committed_data);
2086 J_ASSERT_JH(jh, !jh->b_frozen_data);
2087 return;
2088 case BJ_SyncData:
2089 list = &transaction->t_sync_datalist;
2090 break;
2091 case BJ_Metadata:
2092 transaction->t_nr_buffers++;
2093 list = &transaction->t_buffers;
2094 break;
2095 case BJ_Forget:
2096 list = &transaction->t_forget;
2097 break;
2098 case BJ_IO:
2099 list = &transaction->t_iobuf_list;
2100 break;
2101 case BJ_Shadow:
2102 list = &transaction->t_shadow_list;
2103 break;
2104 case BJ_LogCtl:
2105 list = &transaction->t_log_list;
2106 break;
2107 case BJ_Reserved:
2108 list = &transaction->t_reserved_list;
2109 break;
2110 case BJ_Locked:
2111 list = &transaction->t_locked_list;
2112 break;
2113 }
2114
2115 __blist_add_buffer(list, jh);
2116 jh->b_jlist = jlist;
2117
2118 if (was_dirty)
2119 set_buffer_jbddirty(bh);
2120}
2121
2122void journal_file_buffer(struct journal_head *jh,
2123 transaction_t *transaction, int jlist)
2124{
2125 jbd_lock_bh_state(jh2bh(jh));
2126 spin_lock(&transaction->t_journal->j_list_lock);
2127 __journal_file_buffer(jh, transaction, jlist);
2128 spin_unlock(&transaction->t_journal->j_list_lock);
2129 jbd_unlock_bh_state(jh2bh(jh));
2130}
2131
2132/*
2133 * Remove a buffer from its current buffer list in preparation for
2134 * dropping it from its current transaction entirely. If the buffer has
2135 * already started to be used by a subsequent transaction, refile the
2136 * buffer on that transaction's metadata list.
2137 *
2138 * Called under j_list_lock
2139 * Called under jbd_lock_bh_state(jh2bh(jh))
2140 *
2141 * jh and bh may be already free when this function returns
2142 */
2143void __journal_refile_buffer(struct journal_head *jh)
2144{
2145 int was_dirty, jlist;
2146 struct buffer_head *bh = jh2bh(jh);
2147
2148 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2149 if (jh->b_transaction)
2150 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2151
2152 /* If the buffer is now unused, just drop it. */
2153 if (jh->b_next_transaction == NULL) {
2154 __journal_unfile_buffer(jh);
2155 return;
2156 }
2157
2158 /*
2159 * It has been modified by a later transaction: add it to the new
2160 * transaction's metadata list.
2161 */
2162
2163 was_dirty = test_clear_buffer_jbddirty(bh);
2164 __journal_temp_unlink_buffer(jh);
2165 /*
2166 * We set b_transaction here because b_next_transaction will inherit
2167 * our jh reference and thus __journal_file_buffer() must not take a
2168 * new one.
2169 */
2170 jh->b_transaction = jh->b_next_transaction;
2171 jh->b_next_transaction = NULL;
2172 if (buffer_freed(bh))
2173 jlist = BJ_Forget;
2174 else if (jh->b_modified)
2175 jlist = BJ_Metadata;
2176 else
2177 jlist = BJ_Reserved;
2178 __journal_file_buffer(jh, jh->b_transaction, jlist);
2179 J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2180
2181 if (was_dirty)
2182 set_buffer_jbddirty(bh);
2183}
2184
2185/*
2186 * __journal_refile_buffer() with necessary locking added. We take our bh
2187 * reference so that we can safely unlock bh.
2188 *
2189 * The jh and bh may be freed by this call.
2190 */
2191void journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2192{
2193 struct buffer_head *bh = jh2bh(jh);
2194
2195 /* Get reference so that buffer cannot be freed before we unlock it */
2196 get_bh(bh);
2197 jbd_lock_bh_state(bh);
2198 spin_lock(&journal->j_list_lock);
2199 __journal_refile_buffer(jh);
2200 jbd_unlock_bh_state(bh);
2201 spin_unlock(&journal->j_list_lock);
2202 __brelse(bh);
2203}