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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/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/smp_lock.h>
27#include <linux/mm.h>
28#include <linux/highmem.h>
29
30/*
31 * get_transaction: obtain a new transaction_t object.
32 *
33 * Simply allocate and initialise a new transaction. Create it in
34 * RUNNING state and add it to the current journal (which should not
35 * have an existing running transaction: we only make a new transaction
36 * once we have started to commit the old one).
37 *
38 * Preconditions:
39 * The journal MUST be locked. We don't perform atomic mallocs on the
40 * new transaction and we can't block without protecting against other
41 * processes trying to touch the journal while it is in transition.
42 *
43 * Called under j_state_lock
44 */
45
46static transaction_t *
47get_transaction(journal_t *journal, transaction_t *transaction)
48{
49 transaction->t_journal = journal;
50 transaction->t_state = T_RUNNING;
51 transaction->t_tid = journal->j_transaction_sequence++;
52 transaction->t_expires = jiffies + journal->j_commit_interval;
53 spin_lock_init(&transaction->t_handle_lock);
54
55 /* Set up the commit timer for the new transaction. */
56 journal->j_commit_timer->expires = transaction->t_expires;
57 add_timer(journal->j_commit_timer);
58
59 J_ASSERT(journal->j_running_transaction == NULL);
60 journal->j_running_transaction = transaction;
61
62 return transaction;
63}
64
65/*
66 * Handle management.
67 *
68 * A handle_t is an object which represents a single atomic update to a
69 * filesystem, and which tracks all of the modifications which form part
70 * of that one update.
71 */
72
73/*
74 * start_this_handle: Given a handle, deal with any locking or stalling
75 * needed to make sure that there is enough journal space for the handle
76 * to begin. Attach the handle to a transaction and set up the
77 * transaction's buffer credits.
78 */
79
80static int start_this_handle(journal_t *journal, handle_t *handle)
81{
82 transaction_t *transaction;
83 int needed;
84 int nblocks = handle->h_buffer_credits;
85 transaction_t *new_transaction = NULL;
86 int ret = 0;
87
88 if (nblocks > journal->j_max_transaction_buffers) {
89 printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
90 current->comm, nblocks,
91 journal->j_max_transaction_buffers);
92 ret = -ENOSPC;
93 goto out;
94 }
95
96alloc_transaction:
97 if (!journal->j_running_transaction) {
98 new_transaction = jbd_kmalloc(sizeof(*new_transaction),
99 GFP_NOFS);
100 if (!new_transaction) {
101 ret = -ENOMEM;
102 goto out;
103 }
104 memset(new_transaction, 0, sizeof(*new_transaction));
105 }
106
107 jbd_debug(3, "New handle %p going live.\n", handle);
108
109repeat:
110
111 /*
112 * We need to hold j_state_lock until t_updates has been incremented,
113 * for proper journal barrier handling
114 */
115 spin_lock(&journal->j_state_lock);
116repeat_locked:
117 if (is_journal_aborted(journal) ||
118 (journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) {
119 spin_unlock(&journal->j_state_lock);
120 ret = -EROFS;
121 goto out;
122 }
123
124 /* Wait on the journal's transaction barrier if necessary */
125 if (journal->j_barrier_count) {
126 spin_unlock(&journal->j_state_lock);
127 wait_event(journal->j_wait_transaction_locked,
128 journal->j_barrier_count == 0);
129 goto repeat;
130 }
131
132 if (!journal->j_running_transaction) {
133 if (!new_transaction) {
134 spin_unlock(&journal->j_state_lock);
135 goto alloc_transaction;
136 }
137 get_transaction(journal, new_transaction);
138 new_transaction = NULL;
139 }
140
141 transaction = journal->j_running_transaction;
142
143 /*
144 * If the current transaction is locked down for commit, wait for the
145 * lock to be released.
146 */
147 if (transaction->t_state == T_LOCKED) {
148 DEFINE_WAIT(wait);
149
150 prepare_to_wait(&journal->j_wait_transaction_locked,
151 &wait, TASK_UNINTERRUPTIBLE);
152 spin_unlock(&journal->j_state_lock);
153 schedule();
154 finish_wait(&journal->j_wait_transaction_locked, &wait);
155 goto repeat;
156 }
157
158 /*
159 * If there is not enough space left in the log to write all potential
160 * buffers requested by this operation, we need to stall pending a log
161 * checkpoint to free some more log space.
162 */
163 spin_lock(&transaction->t_handle_lock);
164 needed = transaction->t_outstanding_credits + nblocks;
165
166 if (needed > journal->j_max_transaction_buffers) {
167 /*
168 * If the current transaction is already too large, then start
169 * to commit it: we can then go back and attach this handle to
170 * a new transaction.
171 */
172 DEFINE_WAIT(wait);
173
174 jbd_debug(2, "Handle %p starting new commit...\n", handle);
175 spin_unlock(&transaction->t_handle_lock);
176 prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
177 TASK_UNINTERRUPTIBLE);
178 __log_start_commit(journal, transaction->t_tid);
179 spin_unlock(&journal->j_state_lock);
180 schedule();
181 finish_wait(&journal->j_wait_transaction_locked, &wait);
182 goto repeat;
183 }
184
185 /*
186 * The commit code assumes that it can get enough log space
187 * without forcing a checkpoint. This is *critical* for
188 * correctness: a checkpoint of a buffer which is also
189 * associated with a committing transaction creates a deadlock,
190 * so commit simply cannot force through checkpoints.
191 *
192 * We must therefore ensure the necessary space in the journal
193 * *before* starting to dirty potentially checkpointed buffers
194 * in the new transaction.
195 *
196 * The worst part is, any transaction currently committing can
197 * reduce the free space arbitrarily. Be careful to account for
198 * those buffers when checkpointing.
199 */
200
201 /*
202 * @@@ AKPM: This seems rather over-defensive. We're giving commit
203 * a _lot_ of headroom: 1/4 of the journal plus the size of
204 * the committing transaction. Really, we only need to give it
205 * committing_transaction->t_outstanding_credits plus "enough" for
206 * the log control blocks.
207 * Also, this test is inconsitent with the matching one in
208 * journal_extend().
209 */
210 if (__log_space_left(journal) < jbd_space_needed(journal)) {
211 jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
212 spin_unlock(&transaction->t_handle_lock);
213 __log_wait_for_space(journal);
214 goto repeat_locked;
215 }
216
217 /* OK, account for the buffers that this operation expects to
218 * use and add the handle to the running transaction. */
219
220 handle->h_transaction = transaction;
221 transaction->t_outstanding_credits += nblocks;
222 transaction->t_updates++;
223 transaction->t_handle_count++;
224 jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
225 handle, nblocks, transaction->t_outstanding_credits,
226 __log_space_left(journal));
227 spin_unlock(&transaction->t_handle_lock);
228 spin_unlock(&journal->j_state_lock);
229out:
Jesper Juhlf99d49a2005-11-07 01:01:34 -0800230 kfree(new_transaction);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 return ret;
232}
233
234/* Allocate a new handle. This should probably be in a slab... */
235static handle_t *new_handle(int nblocks)
236{
237 handle_t *handle = jbd_alloc_handle(GFP_NOFS);
238 if (!handle)
239 return NULL;
240 memset(handle, 0, sizeof(*handle));
241 handle->h_buffer_credits = nblocks;
242 handle->h_ref = 1;
243
244 return handle;
245}
246
247/**
248 * handle_t *journal_start() - Obtain a new handle.
249 * @journal: Journal to start transaction on.
250 * @nblocks: number of block buffer we might modify
251 *
252 * We make sure that the transaction can guarantee at least nblocks of
253 * modified buffers in the log. We block until the log can guarantee
254 * that much space.
255 *
256 * This function is visible to journal users (like ext3fs), so is not
257 * called with the journal already locked.
258 *
259 * Return a pointer to a newly allocated handle, or NULL on failure
260 */
261handle_t *journal_start(journal_t *journal, int nblocks)
262{
263 handle_t *handle = journal_current_handle();
264 int err;
265
266 if (!journal)
267 return ERR_PTR(-EROFS);
268
269 if (handle) {
270 J_ASSERT(handle->h_transaction->t_journal == journal);
271 handle->h_ref++;
272 return handle;
273 }
274
275 handle = new_handle(nblocks);
276 if (!handle)
277 return ERR_PTR(-ENOMEM);
278
279 current->journal_info = handle;
280
281 err = start_this_handle(journal, handle);
282 if (err < 0) {
283 jbd_free_handle(handle);
284 current->journal_info = NULL;
285 handle = ERR_PTR(err);
286 }
287 return handle;
288}
289
290/**
291 * int journal_extend() - extend buffer credits.
292 * @handle: handle to 'extend'
293 * @nblocks: nr blocks to try to extend by.
294 *
295 * Some transactions, such as large extends and truncates, can be done
296 * atomically all at once or in several stages. The operation requests
297 * a credit for a number of buffer modications in advance, but can
298 * extend its credit if it needs more.
299 *
300 * journal_extend tries to give the running handle more buffer credits.
301 * It does not guarantee that allocation - this is a best-effort only.
302 * The calling process MUST be able to deal cleanly with a failure to
303 * extend here.
304 *
305 * Return 0 on success, non-zero on failure.
306 *
307 * return code < 0 implies an error
308 * return code > 0 implies normal transaction-full status.
309 */
310int journal_extend(handle_t *handle, int nblocks)
311{
312 transaction_t *transaction = handle->h_transaction;
313 journal_t *journal = transaction->t_journal;
314 int result;
315 int wanted;
316
317 result = -EIO;
318 if (is_handle_aborted(handle))
319 goto out;
320
321 result = 1;
322
323 spin_lock(&journal->j_state_lock);
324
325 /* Don't extend a locked-down transaction! */
326 if (handle->h_transaction->t_state != T_RUNNING) {
327 jbd_debug(3, "denied handle %p %d blocks: "
328 "transaction not running\n", handle, nblocks);
329 goto error_out;
330 }
331
332 spin_lock(&transaction->t_handle_lock);
333 wanted = transaction->t_outstanding_credits + nblocks;
334
335 if (wanted > journal->j_max_transaction_buffers) {
336 jbd_debug(3, "denied handle %p %d blocks: "
337 "transaction too large\n", handle, nblocks);
338 goto unlock;
339 }
340
341 if (wanted > __log_space_left(journal)) {
342 jbd_debug(3, "denied handle %p %d blocks: "
343 "insufficient log space\n", handle, nblocks);
344 goto unlock;
345 }
346
347 handle->h_buffer_credits += nblocks;
348 transaction->t_outstanding_credits += nblocks;
349 result = 0;
350
351 jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
352unlock:
353 spin_unlock(&transaction->t_handle_lock);
354error_out:
355 spin_unlock(&journal->j_state_lock);
356out:
357 return result;
358}
359
360
361/**
362 * int journal_restart() - restart a handle .
363 * @handle: handle to restart
364 * @nblocks: nr credits requested
365 *
366 * Restart a handle for a multi-transaction filesystem
367 * operation.
368 *
369 * If the journal_extend() call above fails to grant new buffer credits
370 * to a running handle, a call to journal_restart will commit the
371 * handle's transaction so far and reattach the handle to a new
372 * transaction capabable of guaranteeing the requested number of
373 * credits.
374 */
375
376int journal_restart(handle_t *handle, int nblocks)
377{
378 transaction_t *transaction = handle->h_transaction;
379 journal_t *journal = transaction->t_journal;
380 int ret;
381
382 /* If we've had an abort of any type, don't even think about
383 * actually doing the restart! */
384 if (is_handle_aborted(handle))
385 return 0;
386
387 /*
388 * First unlink the handle from its current transaction, and start the
389 * commit on that.
390 */
391 J_ASSERT(transaction->t_updates > 0);
392 J_ASSERT(journal_current_handle() == handle);
393
394 spin_lock(&journal->j_state_lock);
395 spin_lock(&transaction->t_handle_lock);
396 transaction->t_outstanding_credits -= handle->h_buffer_credits;
397 transaction->t_updates--;
398
399 if (!transaction->t_updates)
400 wake_up(&journal->j_wait_updates);
401 spin_unlock(&transaction->t_handle_lock);
402
403 jbd_debug(2, "restarting handle %p\n", handle);
404 __log_start_commit(journal, transaction->t_tid);
405 spin_unlock(&journal->j_state_lock);
406
407 handle->h_buffer_credits = nblocks;
408 ret = start_this_handle(journal, handle);
409 return ret;
410}
411
412
413/**
414 * void journal_lock_updates () - establish a transaction barrier.
415 * @journal: Journal to establish a barrier on.
416 *
417 * This locks out any further updates from being started, and blocks
418 * until all existing updates have completed, returning only once the
419 * journal is in a quiescent state with no updates running.
420 *
421 * The journal lock should not be held on entry.
422 */
423void journal_lock_updates(journal_t *journal)
424{
425 DEFINE_WAIT(wait);
426
427 spin_lock(&journal->j_state_lock);
428 ++journal->j_barrier_count;
429
430 /* Wait until there are no running updates */
431 while (1) {
432 transaction_t *transaction = journal->j_running_transaction;
433
434 if (!transaction)
435 break;
436
437 spin_lock(&transaction->t_handle_lock);
438 if (!transaction->t_updates) {
439 spin_unlock(&transaction->t_handle_lock);
440 break;
441 }
442 prepare_to_wait(&journal->j_wait_updates, &wait,
443 TASK_UNINTERRUPTIBLE);
444 spin_unlock(&transaction->t_handle_lock);
445 spin_unlock(&journal->j_state_lock);
446 schedule();
447 finish_wait(&journal->j_wait_updates, &wait);
448 spin_lock(&journal->j_state_lock);
449 }
450 spin_unlock(&journal->j_state_lock);
451
452 /*
453 * We have now established a barrier against other normal updates, but
454 * we also need to barrier against other journal_lock_updates() calls
455 * to make sure that we serialise special journal-locked operations
456 * too.
457 */
458 down(&journal->j_barrier);
459}
460
461/**
462 * void journal_unlock_updates (journal_t* journal) - release barrier
463 * @journal: Journal to release the barrier on.
464 *
465 * Release a transaction barrier obtained with journal_lock_updates().
466 *
467 * Should be called without the journal lock held.
468 */
469void journal_unlock_updates (journal_t *journal)
470{
471 J_ASSERT(journal->j_barrier_count != 0);
472
473 up(&journal->j_barrier);
474 spin_lock(&journal->j_state_lock);
475 --journal->j_barrier_count;
476 spin_unlock(&journal->j_state_lock);
477 wake_up(&journal->j_wait_transaction_locked);
478}
479
480/*
481 * Report any unexpected dirty buffers which turn up. Normally those
482 * indicate an error, but they can occur if the user is running (say)
483 * tune2fs to modify the live filesystem, so we need the option of
484 * continuing as gracefully as possible. #
485 *
486 * The caller should already hold the journal lock and
487 * j_list_lock spinlock: most callers will need those anyway
488 * in order to probe the buffer's journaling state safely.
489 */
490static void jbd_unexpected_dirty_buffer(struct journal_head *jh)
491{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 int jlist;
493
Jan Kara4407c2b2005-09-06 15:19:17 -0700494 /* If this buffer is one which might reasonably be dirty
495 * --- ie. data, or not part of this journal --- then
496 * we're OK to leave it alone, but otherwise we need to
497 * move the dirty bit to the journal's own internal
498 * JBDDirty bit. */
499 jlist = jh->b_jlist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500
Jan Kara4407c2b2005-09-06 15:19:17 -0700501 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
502 jlist == BJ_Shadow || jlist == BJ_Forget) {
503 struct buffer_head *bh = jh2bh(jh);
504
505 if (test_clear_buffer_dirty(bh))
506 set_buffer_jbddirty(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507 }
508}
509
510/*
511 * If the buffer is already part of the current transaction, then there
512 * is nothing we need to do. If it is already part of a prior
513 * transaction which we are still committing to disk, then we need to
514 * make sure that we do not overwrite the old copy: we do copy-out to
515 * preserve the copy going to disk. We also account the buffer against
516 * the handle's metadata buffer credits (unless the buffer is already
517 * part of the transaction, that is).
518 *
519 */
520static int
521do_get_write_access(handle_t *handle, struct journal_head *jh,
522 int force_copy)
523{
524 struct buffer_head *bh;
525 transaction_t *transaction;
526 journal_t *journal;
527 int error;
528 char *frozen_buffer = NULL;
529 int need_copy = 0;
530
531 if (is_handle_aborted(handle))
532 return -EROFS;
533
534 transaction = handle->h_transaction;
535 journal = transaction->t_journal;
536
537 jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy);
538
539 JBUFFER_TRACE(jh, "entry");
540repeat:
541 bh = jh2bh(jh);
542
543 /* @@@ Need to check for errors here at some point. */
544
545 lock_buffer(bh);
546 jbd_lock_bh_state(bh);
547
548 /* We now hold the buffer lock so it is safe to query the buffer
549 * state. Is the buffer dirty?
550 *
551 * If so, there are two possibilities. The buffer may be
552 * non-journaled, and undergoing a quite legitimate writeback.
553 * Otherwise, it is journaled, and we don't expect dirty buffers
554 * in that state (the buffers should be marked JBD_Dirty
555 * instead.) So either the IO is being done under our own
556 * control and this is a bug, or it's a third party IO such as
557 * dump(8) (which may leave the buffer scheduled for read ---
558 * ie. locked but not dirty) or tune2fs (which may actually have
559 * the buffer dirtied, ugh.) */
560
561 if (buffer_dirty(bh)) {
562 /*
563 * First question: is this buffer already part of the current
564 * transaction or the existing committing transaction?
565 */
566 if (jh->b_transaction) {
567 J_ASSERT_JH(jh,
568 jh->b_transaction == transaction ||
569 jh->b_transaction ==
570 journal->j_committing_transaction);
571 if (jh->b_next_transaction)
572 J_ASSERT_JH(jh, jh->b_next_transaction ==
573 transaction);
Jan Kara4407c2b2005-09-06 15:19:17 -0700574 }
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, "Unexpected dirty buffer");
581 jbd_unexpected_dirty_buffer(jh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 }
583
584 unlock_buffer(bh);
585
586 error = -EROFS;
587 if (is_handle_aborted(handle)) {
588 jbd_unlock_bh_state(bh);
589 goto out;
590 }
591 error = 0;
592
593 /*
594 * The buffer is already part of this transaction if b_transaction or
595 * b_next_transaction points to it
596 */
597 if (jh->b_transaction == transaction ||
598 jh->b_next_transaction == transaction)
599 goto done;
600
601 /*
602 * If there is already a copy-out version of this buffer, then we don't
603 * need to make another one
604 */
605 if (jh->b_frozen_data) {
606 JBUFFER_TRACE(jh, "has frozen data");
607 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
608 jh->b_next_transaction = transaction;
609 goto done;
610 }
611
612 /* Is there data here we need to preserve? */
613
614 if (jh->b_transaction && jh->b_transaction != transaction) {
615 JBUFFER_TRACE(jh, "owned by older transaction");
616 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
617 J_ASSERT_JH(jh, jh->b_transaction ==
618 journal->j_committing_transaction);
619
620 /* There is one case we have to be very careful about.
621 * If the committing transaction is currently writing
622 * this buffer out to disk and has NOT made a copy-out,
623 * then we cannot modify the buffer contents at all
624 * right now. The essence of copy-out is that it is the
625 * extra copy, not the primary copy, which gets
626 * journaled. If the primary copy is already going to
627 * disk then we cannot do copy-out here. */
628
629 if (jh->b_jlist == BJ_Shadow) {
630 DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
631 wait_queue_head_t *wqh;
632
633 wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
634
635 JBUFFER_TRACE(jh, "on shadow: sleep");
636 jbd_unlock_bh_state(bh);
637 /* commit wakes up all shadow buffers after IO */
638 for ( ; ; ) {
639 prepare_to_wait(wqh, &wait.wait,
640 TASK_UNINTERRUPTIBLE);
641 if (jh->b_jlist != BJ_Shadow)
642 break;
643 schedule();
644 }
645 finish_wait(wqh, &wait.wait);
646 goto repeat;
647 }
648
649 /* Only do the copy if the currently-owning transaction
650 * still needs it. If it is on the Forget list, the
651 * committing transaction is past that stage. The
652 * buffer had better remain locked during the kmalloc,
653 * but that should be true --- we hold the journal lock
654 * still and the buffer is already on the BUF_JOURNAL
655 * list so won't be flushed.
656 *
657 * Subtle point, though: if this is a get_undo_access,
658 * then we will be relying on the frozen_data to contain
659 * the new value of the committed_data record after the
660 * transaction, so we HAVE to force the frozen_data copy
661 * in that case. */
662
663 if (jh->b_jlist != BJ_Forget || force_copy) {
664 JBUFFER_TRACE(jh, "generate frozen data");
665 if (!frozen_buffer) {
666 JBUFFER_TRACE(jh, "allocate memory for buffer");
667 jbd_unlock_bh_state(bh);
668 frozen_buffer = jbd_kmalloc(jh2bh(jh)->b_size,
669 GFP_NOFS);
670 if (!frozen_buffer) {
671 printk(KERN_EMERG
672 "%s: OOM for frozen_buffer\n",
673 __FUNCTION__);
674 JBUFFER_TRACE(jh, "oom!");
675 error = -ENOMEM;
676 jbd_lock_bh_state(bh);
677 goto done;
678 }
679 goto repeat;
680 }
681 jh->b_frozen_data = frozen_buffer;
682 frozen_buffer = NULL;
683 need_copy = 1;
684 }
685 jh->b_next_transaction = transaction;
686 }
687
688
689 /*
690 * Finally, if the buffer is not journaled right now, we need to make
691 * sure it doesn't get written to disk before the caller actually
692 * commits the new data
693 */
694 if (!jh->b_transaction) {
695 JBUFFER_TRACE(jh, "no transaction");
696 J_ASSERT_JH(jh, !jh->b_next_transaction);
697 jh->b_transaction = transaction;
698 JBUFFER_TRACE(jh, "file as BJ_Reserved");
699 spin_lock(&journal->j_list_lock);
700 __journal_file_buffer(jh, transaction, BJ_Reserved);
701 spin_unlock(&journal->j_list_lock);
702 }
703
704done:
705 if (need_copy) {
706 struct page *page;
707 int offset;
708 char *source;
709
710 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
711 "Possible IO failure.\n");
712 page = jh2bh(jh)->b_page;
713 offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK;
714 source = kmap_atomic(page, KM_USER0);
715 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
716 kunmap_atomic(source, KM_USER0);
717 }
718 jbd_unlock_bh_state(bh);
719
720 /*
721 * If we are about to journal a buffer, then any revoke pending on it is
722 * no longer valid
723 */
724 journal_cancel_revoke(handle, jh);
725
726out:
Jesper Juhlf99d49a2005-11-07 01:01:34 -0800727 kfree(frozen_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728
729 JBUFFER_TRACE(jh, "exit");
730 return error;
731}
732
733/**
734 * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
735 * @handle: transaction to add buffer modifications to
736 * @bh: bh to be used for metadata writes
737 * @credits: variable that will receive credits for the buffer
738 *
739 * Returns an error code or 0 on success.
740 *
741 * In full data journalling mode the buffer may be of type BJ_AsyncData,
742 * because we're write()ing a buffer which is also part of a shared mapping.
743 */
744
745int journal_get_write_access(handle_t *handle, struct buffer_head *bh)
746{
747 struct journal_head *jh = journal_add_journal_head(bh);
748 int rc;
749
750 /* We do not want to get caught playing with fields which the
751 * log thread also manipulates. Make sure that the buffer
752 * completes any outstanding IO before proceeding. */
753 rc = do_get_write_access(handle, jh, 0);
754 journal_put_journal_head(jh);
755 return rc;
756}
757
758
759/*
760 * When the user wants to journal a newly created buffer_head
761 * (ie. getblk() returned a new buffer and we are going to populate it
762 * manually rather than reading off disk), then we need to keep the
763 * buffer_head locked until it has been completely filled with new
764 * data. In this case, we should be able to make the assertion that
765 * the bh is not already part of an existing transaction.
766 *
767 * The buffer should already be locked by the caller by this point.
768 * There is no lock ranking violation: it was a newly created,
769 * unlocked buffer beforehand. */
770
771/**
772 * int journal_get_create_access () - notify intent to use newly created bh
773 * @handle: transaction to new buffer to
774 * @bh: new buffer.
775 *
776 * Call this if you create a new bh.
777 */
778int journal_get_create_access(handle_t *handle, struct buffer_head *bh)
779{
780 transaction_t *transaction = handle->h_transaction;
781 journal_t *journal = transaction->t_journal;
782 struct journal_head *jh = journal_add_journal_head(bh);
783 int err;
784
785 jbd_debug(5, "journal_head %p\n", jh);
786 err = -EROFS;
787 if (is_handle_aborted(handle))
788 goto out;
789 err = 0;
790
791 JBUFFER_TRACE(jh, "entry");
792 /*
793 * The buffer may already belong to this transaction due to pre-zeroing
794 * in the filesystem's new_block code. It may also be on the previous,
795 * committing transaction's lists, but it HAS to be in Forget state in
796 * that case: the transaction must have deleted the buffer for it to be
797 * reused here.
798 */
799 jbd_lock_bh_state(bh);
800 spin_lock(&journal->j_list_lock);
801 J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
802 jh->b_transaction == NULL ||
803 (jh->b_transaction == journal->j_committing_transaction &&
804 jh->b_jlist == BJ_Forget)));
805
806 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
807 J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
808
809 if (jh->b_transaction == NULL) {
810 jh->b_transaction = transaction;
811 JBUFFER_TRACE(jh, "file as BJ_Reserved");
812 __journal_file_buffer(jh, transaction, BJ_Reserved);
813 } else if (jh->b_transaction == journal->j_committing_transaction) {
814 JBUFFER_TRACE(jh, "set next transaction");
815 jh->b_next_transaction = transaction;
816 }
817 spin_unlock(&journal->j_list_lock);
818 jbd_unlock_bh_state(bh);
819
820 /*
821 * akpm: I added this. ext3_alloc_branch can pick up new indirect
822 * blocks which contain freed but then revoked metadata. We need
823 * to cancel the revoke in case we end up freeing it yet again
824 * and the reallocating as data - this would cause a second revoke,
825 * which hits an assertion error.
826 */
827 JBUFFER_TRACE(jh, "cancelling revoke");
828 journal_cancel_revoke(handle, jh);
829 journal_put_journal_head(jh);
830out:
831 return err;
832}
833
834/**
835 * int journal_get_undo_access() - Notify intent to modify metadata with
836 * non-rewindable consequences
837 * @handle: transaction
838 * @bh: buffer to undo
839 * @credits: store the number of taken credits here (if not NULL)
840 *
841 * Sometimes there is a need to distinguish between metadata which has
842 * been committed to disk and that which has not. The ext3fs code uses
843 * this for freeing and allocating space, we have to make sure that we
844 * do not reuse freed space until the deallocation has been committed,
845 * since if we overwrote that space we would make the delete
846 * un-rewindable in case of a crash.
847 *
848 * To deal with that, journal_get_undo_access requests write access to a
849 * buffer for parts of non-rewindable operations such as delete
850 * operations on the bitmaps. The journaling code must keep a copy of
851 * the buffer's contents prior to the undo_access call until such time
852 * as we know that the buffer has definitely been committed to disk.
853 *
854 * We never need to know which transaction the committed data is part
855 * of, buffers touched here are guaranteed to be dirtied later and so
856 * will be committed to a new transaction in due course, at which point
857 * we can discard the old committed data pointer.
858 *
859 * Returns error number or 0 on success.
860 */
861int journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
862{
863 int err;
864 struct journal_head *jh = journal_add_journal_head(bh);
865 char *committed_data = NULL;
866
867 JBUFFER_TRACE(jh, "entry");
868
869 /*
870 * Do this first --- it can drop the journal lock, so we want to
871 * make sure that obtaining the committed_data is done
872 * atomically wrt. completion of any outstanding commits.
873 */
874 err = do_get_write_access(handle, jh, 1);
875 if (err)
876 goto out;
877
878repeat:
879 if (!jh->b_committed_data) {
880 committed_data = jbd_kmalloc(jh2bh(jh)->b_size, GFP_NOFS);
881 if (!committed_data) {
882 printk(KERN_EMERG "%s: No memory for committed data\n",
883 __FUNCTION__);
884 err = -ENOMEM;
885 goto out;
886 }
887 }
888
889 jbd_lock_bh_state(bh);
890 if (!jh->b_committed_data) {
891 /* Copy out the current buffer contents into the
892 * preserved, committed copy. */
893 JBUFFER_TRACE(jh, "generate b_committed data");
894 if (!committed_data) {
895 jbd_unlock_bh_state(bh);
896 goto repeat;
897 }
898
899 jh->b_committed_data = committed_data;
900 committed_data = NULL;
901 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
902 }
903 jbd_unlock_bh_state(bh);
904out:
905 journal_put_journal_head(jh);
Jesper Juhlf99d49a2005-11-07 01:01:34 -0800906 kfree(committed_data);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700907 return err;
908}
909
910/**
911 * int journal_dirty_data() - mark a buffer as containing dirty data which
912 * needs to be flushed before we can commit the
913 * current transaction.
914 * @handle: transaction
915 * @bh: bufferhead to mark
916 *
917 * The buffer is placed on the transaction's data list and is marked as
918 * belonging to the transaction.
919 *
920 * Returns error number or 0 on success.
921 *
922 * journal_dirty_data() can be called via page_launder->ext3_writepage
923 * by kswapd.
924 */
925int journal_dirty_data(handle_t *handle, struct buffer_head *bh)
926{
927 journal_t *journal = handle->h_transaction->t_journal;
928 int need_brelse = 0;
929 struct journal_head *jh;
930
931 if (is_handle_aborted(handle))
932 return 0;
933
934 jh = journal_add_journal_head(bh);
935 JBUFFER_TRACE(jh, "entry");
936
937 /*
938 * The buffer could *already* be dirty. Writeout can start
939 * at any time.
940 */
941 jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
942
943 /*
944 * What if the buffer is already part of a running transaction?
945 *
946 * There are two cases:
947 * 1) It is part of the current running transaction. Refile it,
948 * just in case we have allocated it as metadata, deallocated
949 * it, then reallocated it as data.
950 * 2) It is part of the previous, still-committing transaction.
951 * If all we want to do is to guarantee that the buffer will be
952 * written to disk before this new transaction commits, then
953 * being sure that the *previous* transaction has this same
954 * property is sufficient for us! Just leave it on its old
955 * transaction.
956 *
957 * In case (2), the buffer must not already exist as metadata
958 * --- that would violate write ordering (a transaction is free
959 * to write its data at any point, even before the previous
960 * committing transaction has committed). The caller must
961 * never, ever allow this to happen: there's nothing we can do
962 * about it in this layer.
963 */
964 jbd_lock_bh_state(bh);
965 spin_lock(&journal->j_list_lock);
966 if (jh->b_transaction) {
967 JBUFFER_TRACE(jh, "has transaction");
968 if (jh->b_transaction != handle->h_transaction) {
969 JBUFFER_TRACE(jh, "belongs to older transaction");
970 J_ASSERT_JH(jh, jh->b_transaction ==
971 journal->j_committing_transaction);
972
973 /* @@@ IS THIS TRUE ? */
974 /*
975 * Not any more. Scenario: someone does a write()
976 * in data=journal mode. The buffer's transaction has
977 * moved into commit. Then someone does another
978 * write() to the file. We do the frozen data copyout
979 * and set b_next_transaction to point to j_running_t.
980 * And while we're in that state, someone does a
981 * writepage() in an attempt to pageout the same area
982 * of the file via a shared mapping. At present that
983 * calls journal_dirty_data(), and we get right here.
984 * It may be too late to journal the data. Simply
985 * falling through to the next test will suffice: the
986 * data will be dirty and wil be checkpointed. The
987 * ordering comments in the next comment block still
988 * apply.
989 */
990 //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
991
992 /*
993 * If we're journalling data, and this buffer was
994 * subject to a write(), it could be metadata, forget
995 * or shadow against the committing transaction. Now,
996 * someone has dirtied the same darn page via a mapping
997 * and it is being writepage()'d.
998 * We *could* just steal the page from commit, with some
999 * fancy locking there. Instead, we just skip it -
1000 * don't tie the page's buffers to the new transaction
1001 * at all.
1002 * Implication: if we crash before the writepage() data
1003 * is written into the filesystem, recovery will replay
1004 * the write() data.
1005 */
1006 if (jh->b_jlist != BJ_None &&
1007 jh->b_jlist != BJ_SyncData &&
1008 jh->b_jlist != BJ_Locked) {
1009 JBUFFER_TRACE(jh, "Not stealing");
1010 goto no_journal;
1011 }
1012
1013 /*
1014 * This buffer may be undergoing writeout in commit. We
1015 * can't return from here and let the caller dirty it
1016 * again because that can cause the write-out loop in
1017 * commit to never terminate.
1018 */
1019 if (buffer_dirty(bh)) {
1020 get_bh(bh);
1021 spin_unlock(&journal->j_list_lock);
1022 jbd_unlock_bh_state(bh);
1023 need_brelse = 1;
1024 sync_dirty_buffer(bh);
1025 jbd_lock_bh_state(bh);
1026 spin_lock(&journal->j_list_lock);
1027 /* The buffer may become locked again at any
1028 time if it is redirtied */
1029 }
1030
1031 /* journal_clean_data_list() may have got there first */
1032 if (jh->b_transaction != NULL) {
1033 JBUFFER_TRACE(jh, "unfile from commit");
1034 __journal_temp_unlink_buffer(jh);
1035 /* It still points to the committing
1036 * transaction; move it to this one so
1037 * that the refile assert checks are
1038 * happy. */
1039 jh->b_transaction = handle->h_transaction;
1040 }
1041 /* The buffer will be refiled below */
1042
1043 }
1044 /*
1045 * Special case --- the buffer might actually have been
1046 * allocated and then immediately deallocated in the previous,
1047 * committing transaction, so might still be left on that
1048 * transaction's metadata lists.
1049 */
1050 if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
1051 JBUFFER_TRACE(jh, "not on correct data list: unfile");
1052 J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
1053 __journal_temp_unlink_buffer(jh);
1054 jh->b_transaction = handle->h_transaction;
1055 JBUFFER_TRACE(jh, "file as data");
1056 __journal_file_buffer(jh, handle->h_transaction,
1057 BJ_SyncData);
1058 }
1059 } else {
1060 JBUFFER_TRACE(jh, "not on a transaction");
1061 __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
1062 }
1063no_journal:
1064 spin_unlock(&journal->j_list_lock);
1065 jbd_unlock_bh_state(bh);
1066 if (need_brelse) {
1067 BUFFER_TRACE(bh, "brelse");
1068 __brelse(bh);
1069 }
1070 JBUFFER_TRACE(jh, "exit");
1071 journal_put_journal_head(jh);
1072 return 0;
1073}
1074
1075/**
1076 * int journal_dirty_metadata() - mark a buffer as containing dirty metadata
1077 * @handle: transaction to add buffer to.
1078 * @bh: buffer to mark
1079 *
1080 * mark dirty metadata which needs to be journaled as part of the current
1081 * transaction.
1082 *
1083 * The buffer is placed on the transaction's metadata list and is marked
1084 * as belonging to the transaction.
1085 *
1086 * Returns error number or 0 on success.
1087 *
1088 * Special care needs to be taken if the buffer already belongs to the
1089 * current committing transaction (in which case we should have frozen
1090 * data present for that commit). In that case, we don't relink the
1091 * buffer: that only gets done when the old transaction finally
1092 * completes its commit.
1093 */
1094int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1095{
1096 transaction_t *transaction = handle->h_transaction;
1097 journal_t *journal = transaction->t_journal;
1098 struct journal_head *jh = bh2jh(bh);
1099
1100 jbd_debug(5, "journal_head %p\n", jh);
1101 JBUFFER_TRACE(jh, "entry");
1102 if (is_handle_aborted(handle))
1103 goto out;
1104
1105 jbd_lock_bh_state(bh);
1106
1107 if (jh->b_modified == 0) {
1108 /*
1109 * This buffer's got modified and becoming part
1110 * of the transaction. This needs to be done
1111 * once a transaction -bzzz
1112 */
1113 jh->b_modified = 1;
1114 J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
1115 handle->h_buffer_credits--;
1116 }
1117
1118 /*
1119 * fastpath, to avoid expensive locking. If this buffer is already
1120 * on the running transaction's metadata list there is nothing to do.
1121 * Nobody can take it off again because there is a handle open.
1122 * I _think_ we're OK here with SMP barriers - a mistaken decision will
1123 * result in this test being false, so we go in and take the locks.
1124 */
1125 if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1126 JBUFFER_TRACE(jh, "fastpath");
1127 J_ASSERT_JH(jh, jh->b_transaction ==
1128 journal->j_running_transaction);
1129 goto out_unlock_bh;
1130 }
1131
1132 set_buffer_jbddirty(bh);
1133
1134 /*
1135 * Metadata already on the current transaction list doesn't
1136 * need to be filed. Metadata on another transaction's list must
1137 * be committing, and will be refiled once the commit completes:
1138 * leave it alone for now.
1139 */
1140 if (jh->b_transaction != transaction) {
1141 JBUFFER_TRACE(jh, "already on other transaction");
1142 J_ASSERT_JH(jh, jh->b_transaction ==
1143 journal->j_committing_transaction);
1144 J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
1145 /* And this case is illegal: we can't reuse another
1146 * transaction's data buffer, ever. */
1147 goto out_unlock_bh;
1148 }
1149
1150 /* That test should have eliminated the following case: */
1151 J_ASSERT_JH(jh, jh->b_frozen_data == 0);
1152
1153 JBUFFER_TRACE(jh, "file as BJ_Metadata");
1154 spin_lock(&journal->j_list_lock);
1155 __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1156 spin_unlock(&journal->j_list_lock);
1157out_unlock_bh:
1158 jbd_unlock_bh_state(bh);
1159out:
1160 JBUFFER_TRACE(jh, "exit");
1161 return 0;
1162}
1163
1164/*
1165 * journal_release_buffer: undo a get_write_access without any buffer
1166 * updates, if the update decided in the end that it didn't need access.
1167 *
1168 */
1169void
1170journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1171{
1172 BUFFER_TRACE(bh, "entry");
1173}
1174
1175/**
1176 * void journal_forget() - bforget() for potentially-journaled buffers.
1177 * @handle: transaction handle
1178 * @bh: bh to 'forget'
1179 *
1180 * We can only do the bforget if there are no commits pending against the
1181 * buffer. If the buffer is dirty in the current running transaction we
1182 * can safely unlink it.
1183 *
1184 * bh may not be a journalled buffer at all - it may be a non-JBD
1185 * buffer which came off the hashtable. Check for this.
1186 *
1187 * Decrements bh->b_count by one.
1188 *
1189 * Allow this call even if the handle has aborted --- it may be part of
1190 * the caller's cleanup after an abort.
1191 */
1192int journal_forget (handle_t *handle, struct buffer_head *bh)
1193{
1194 transaction_t *transaction = handle->h_transaction;
1195 journal_t *journal = transaction->t_journal;
1196 struct journal_head *jh;
1197 int drop_reserve = 0;
1198 int err = 0;
1199
1200 BUFFER_TRACE(bh, "entry");
1201
1202 jbd_lock_bh_state(bh);
1203 spin_lock(&journal->j_list_lock);
1204
1205 if (!buffer_jbd(bh))
1206 goto not_jbd;
1207 jh = bh2jh(bh);
1208
1209 /* Critical error: attempting to delete a bitmap buffer, maybe?
1210 * Don't do any jbd operations, and return an error. */
1211 if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1212 "inconsistent data on disk")) {
1213 err = -EIO;
1214 goto not_jbd;
1215 }
1216
1217 /*
1218 * The buffer's going from the transaction, we must drop
1219 * all references -bzzz
1220 */
1221 jh->b_modified = 0;
1222
1223 if (jh->b_transaction == handle->h_transaction) {
1224 J_ASSERT_JH(jh, !jh->b_frozen_data);
1225
1226 /* If we are forgetting a buffer which is already part
1227 * of this transaction, then we can just drop it from
1228 * the transaction immediately. */
1229 clear_buffer_dirty(bh);
1230 clear_buffer_jbddirty(bh);
1231
1232 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1233
1234 drop_reserve = 1;
1235
1236 /*
1237 * We are no longer going to journal this buffer.
1238 * However, the commit of this transaction is still
1239 * important to the buffer: the delete that we are now
1240 * processing might obsolete an old log entry, so by
1241 * committing, we can satisfy the buffer's checkpoint.
1242 *
1243 * So, if we have a checkpoint on the buffer, we should
1244 * now refile the buffer on our BJ_Forget list so that
1245 * we know to remove the checkpoint after we commit.
1246 */
1247
1248 if (jh->b_cp_transaction) {
1249 __journal_temp_unlink_buffer(jh);
1250 __journal_file_buffer(jh, transaction, BJ_Forget);
1251 } else {
1252 __journal_unfile_buffer(jh);
1253 journal_remove_journal_head(bh);
1254 __brelse(bh);
1255 if (!buffer_jbd(bh)) {
1256 spin_unlock(&journal->j_list_lock);
1257 jbd_unlock_bh_state(bh);
1258 __bforget(bh);
1259 goto drop;
1260 }
1261 }
1262 } else if (jh->b_transaction) {
1263 J_ASSERT_JH(jh, (jh->b_transaction ==
1264 journal->j_committing_transaction));
1265 /* However, if the buffer is still owned by a prior
1266 * (committing) transaction, we can't drop it yet... */
1267 JBUFFER_TRACE(jh, "belongs to older transaction");
1268 /* ... but we CAN drop it from the new transaction if we
1269 * have also modified it since the original commit. */
1270
1271 if (jh->b_next_transaction) {
1272 J_ASSERT(jh->b_next_transaction == transaction);
1273 jh->b_next_transaction = NULL;
1274 drop_reserve = 1;
1275 }
1276 }
1277
1278not_jbd:
1279 spin_unlock(&journal->j_list_lock);
1280 jbd_unlock_bh_state(bh);
1281 __brelse(bh);
1282drop:
1283 if (drop_reserve) {
1284 /* no need to reserve log space for this block -bzzz */
1285 handle->h_buffer_credits++;
1286 }
1287 return err;
1288}
1289
1290/**
1291 * int journal_stop() - complete a transaction
1292 * @handle: tranaction to complete.
1293 *
1294 * All done for a particular handle.
1295 *
1296 * There is not much action needed here. We just return any remaining
1297 * buffer credits to the transaction and remove the handle. The only
1298 * complication is that we need to start a commit operation if the
1299 * filesystem is marked for synchronous update.
1300 *
1301 * journal_stop itself will not usually return an error, but it may
1302 * do so in unusual circumstances. In particular, expect it to
1303 * return -EIO if a journal_abort has been executed since the
1304 * transaction began.
1305 */
1306int journal_stop(handle_t *handle)
1307{
1308 transaction_t *transaction = handle->h_transaction;
1309 journal_t *journal = transaction->t_journal;
1310 int old_handle_count, err;
1311
1312 J_ASSERT(transaction->t_updates > 0);
1313 J_ASSERT(journal_current_handle() == handle);
1314
1315 if (is_handle_aborted(handle))
1316 err = -EIO;
1317 else
1318 err = 0;
1319
1320 if (--handle->h_ref > 0) {
1321 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1322 handle->h_ref);
1323 return err;
1324 }
1325
1326 jbd_debug(4, "Handle %p going down\n", handle);
1327
1328 /*
1329 * Implement synchronous transaction batching. If the handle
1330 * was synchronous, don't force a commit immediately. Let's
1331 * yield and let another thread piggyback onto this transaction.
1332 * Keep doing that while new threads continue to arrive.
1333 * It doesn't cost much - we're about to run a commit and sleep
1334 * on IO anyway. Speeds up many-threaded, many-dir operations
1335 * by 30x or more...
1336 */
1337 if (handle->h_sync) {
1338 do {
1339 old_handle_count = transaction->t_handle_count;
Nishanth Aravamudan041e0e32005-09-10 00:27:23 -07001340 schedule_timeout_uninterruptible(1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341 } while (old_handle_count != transaction->t_handle_count);
1342 }
1343
1344 current->journal_info = NULL;
1345 spin_lock(&journal->j_state_lock);
1346 spin_lock(&transaction->t_handle_lock);
1347 transaction->t_outstanding_credits -= handle->h_buffer_credits;
1348 transaction->t_updates--;
1349 if (!transaction->t_updates) {
1350 wake_up(&journal->j_wait_updates);
1351 if (journal->j_barrier_count)
1352 wake_up(&journal->j_wait_transaction_locked);
1353 }
1354
1355 /*
1356 * If the handle is marked SYNC, we need to set another commit
1357 * going! We also want to force a commit if the current
1358 * transaction is occupying too much of the log, or if the
1359 * transaction is too old now.
1360 */
1361 if (handle->h_sync ||
1362 transaction->t_outstanding_credits >
1363 journal->j_max_transaction_buffers ||
1364 time_after_eq(jiffies, transaction->t_expires)) {
1365 /* Do this even for aborted journals: an abort still
1366 * completes the commit thread, it just doesn't write
1367 * anything to disk. */
1368 tid_t tid = transaction->t_tid;
1369
1370 spin_unlock(&transaction->t_handle_lock);
1371 jbd_debug(2, "transaction too old, requesting commit for "
1372 "handle %p\n", handle);
1373 /* This is non-blocking */
1374 __log_start_commit(journal, transaction->t_tid);
1375 spin_unlock(&journal->j_state_lock);
1376
1377 /*
1378 * Special case: JFS_SYNC synchronous updates require us
1379 * to wait for the commit to complete.
1380 */
1381 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1382 err = log_wait_commit(journal, tid);
1383 } else {
1384 spin_unlock(&transaction->t_handle_lock);
1385 spin_unlock(&journal->j_state_lock);
1386 }
1387
1388 jbd_free_handle(handle);
1389 return err;
1390}
1391
1392/**int journal_force_commit() - force any uncommitted transactions
1393 * @journal: journal to force
1394 *
1395 * For synchronous operations: force any uncommitted transactions
1396 * to disk. May seem kludgy, but it reuses all the handle batching
1397 * code in a very simple manner.
1398 */
1399int journal_force_commit(journal_t *journal)
1400{
1401 handle_t *handle;
1402 int ret;
1403
1404 handle = journal_start(journal, 1);
1405 if (IS_ERR(handle)) {
1406 ret = PTR_ERR(handle);
1407 } else {
1408 handle->h_sync = 1;
1409 ret = journal_stop(handle);
1410 }
1411 return ret;
1412}
1413
1414/*
1415 *
1416 * List management code snippets: various functions for manipulating the
1417 * transaction buffer lists.
1418 *
1419 */
1420
1421/*
1422 * Append a buffer to a transaction list, given the transaction's list head
1423 * pointer.
1424 *
1425 * j_list_lock is held.
1426 *
1427 * jbd_lock_bh_state(jh2bh(jh)) is held.
1428 */
1429
1430static inline void
1431__blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1432{
1433 if (!*list) {
1434 jh->b_tnext = jh->b_tprev = jh;
1435 *list = jh;
1436 } else {
1437 /* Insert at the tail of the list to preserve order */
1438 struct journal_head *first = *list, *last = first->b_tprev;
1439 jh->b_tprev = last;
1440 jh->b_tnext = first;
1441 last->b_tnext = first->b_tprev = jh;
1442 }
1443}
1444
1445/*
1446 * Remove a buffer from a transaction list, given the transaction's list
1447 * head pointer.
1448 *
1449 * Called with j_list_lock held, and the journal may not be locked.
1450 *
1451 * jbd_lock_bh_state(jh2bh(jh)) is held.
1452 */
1453
1454static inline void
1455__blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1456{
1457 if (*list == jh) {
1458 *list = jh->b_tnext;
1459 if (*list == jh)
1460 *list = NULL;
1461 }
1462 jh->b_tprev->b_tnext = jh->b_tnext;
1463 jh->b_tnext->b_tprev = jh->b_tprev;
1464}
1465
1466/*
1467 * Remove a buffer from the appropriate transaction list.
1468 *
1469 * Note that this function can *change* the value of
1470 * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
1471 * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller
1472 * is holding onto a copy of one of thee pointers, it could go bad.
1473 * Generally the caller needs to re-read the pointer from the transaction_t.
1474 *
1475 * Called under j_list_lock. The journal may not be locked.
1476 */
1477void __journal_temp_unlink_buffer(struct journal_head *jh)
1478{
1479 struct journal_head **list = NULL;
1480 transaction_t *transaction;
1481 struct buffer_head *bh = jh2bh(jh);
1482
1483 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1484 transaction = jh->b_transaction;
1485 if (transaction)
1486 assert_spin_locked(&transaction->t_journal->j_list_lock);
1487
1488 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1489 if (jh->b_jlist != BJ_None)
1490 J_ASSERT_JH(jh, transaction != 0);
1491
1492 switch (jh->b_jlist) {
1493 case BJ_None:
1494 return;
1495 case BJ_SyncData:
1496 list = &transaction->t_sync_datalist;
1497 break;
1498 case BJ_Metadata:
1499 transaction->t_nr_buffers--;
1500 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1501 list = &transaction->t_buffers;
1502 break;
1503 case BJ_Forget:
1504 list = &transaction->t_forget;
1505 break;
1506 case BJ_IO:
1507 list = &transaction->t_iobuf_list;
1508 break;
1509 case BJ_Shadow:
1510 list = &transaction->t_shadow_list;
1511 break;
1512 case BJ_LogCtl:
1513 list = &transaction->t_log_list;
1514 break;
1515 case BJ_Reserved:
1516 list = &transaction->t_reserved_list;
1517 break;
1518 case BJ_Locked:
1519 list = &transaction->t_locked_list;
1520 break;
1521 }
1522
1523 __blist_del_buffer(list, jh);
1524 jh->b_jlist = BJ_None;
1525 if (test_clear_buffer_jbddirty(bh))
1526 mark_buffer_dirty(bh); /* Expose it to the VM */
1527}
1528
1529void __journal_unfile_buffer(struct journal_head *jh)
1530{
1531 __journal_temp_unlink_buffer(jh);
1532 jh->b_transaction = NULL;
1533}
1534
1535void journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1536{
1537 jbd_lock_bh_state(jh2bh(jh));
1538 spin_lock(&journal->j_list_lock);
1539 __journal_unfile_buffer(jh);
1540 spin_unlock(&journal->j_list_lock);
1541 jbd_unlock_bh_state(jh2bh(jh));
1542}
1543
1544/*
1545 * Called from journal_try_to_free_buffers().
1546 *
1547 * Called under jbd_lock_bh_state(bh)
1548 */
1549static void
1550__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1551{
1552 struct journal_head *jh;
1553
1554 jh = bh2jh(bh);
1555
1556 if (buffer_locked(bh) || buffer_dirty(bh))
1557 goto out;
1558
1559 if (jh->b_next_transaction != 0)
1560 goto out;
1561
1562 spin_lock(&journal->j_list_lock);
1563 if (jh->b_transaction != 0 && jh->b_cp_transaction == 0) {
1564 if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
1565 /* A written-back ordered data buffer */
1566 JBUFFER_TRACE(jh, "release data");
1567 __journal_unfile_buffer(jh);
1568 journal_remove_journal_head(bh);
1569 __brelse(bh);
1570 }
1571 } else if (jh->b_cp_transaction != 0 && jh->b_transaction == 0) {
1572 /* written-back checkpointed metadata buffer */
1573 if (jh->b_jlist == BJ_None) {
1574 JBUFFER_TRACE(jh, "remove from checkpoint list");
1575 __journal_remove_checkpoint(jh);
1576 journal_remove_journal_head(bh);
1577 __brelse(bh);
1578 }
1579 }
1580 spin_unlock(&journal->j_list_lock);
1581out:
1582 return;
1583}
1584
1585
1586/**
1587 * int journal_try_to_free_buffers() - try to free page buffers.
1588 * @journal: journal for operation
1589 * @page: to try and free
1590 * @unused_gfp_mask: unused
1591 *
1592 *
1593 * For all the buffers on this page,
1594 * if they are fully written out ordered data, move them onto BUF_CLEAN
1595 * so try_to_free_buffers() can reap them.
1596 *
1597 * This function returns non-zero if we wish try_to_free_buffers()
1598 * to be called. We do this if the page is releasable by try_to_free_buffers().
1599 * We also do it if the page has locked or dirty buffers and the caller wants
1600 * us to perform sync or async writeout.
1601 *
1602 * This complicates JBD locking somewhat. We aren't protected by the
1603 * BKL here. We wish to remove the buffer from its committing or
1604 * running transaction's ->t_datalist via __journal_unfile_buffer.
1605 *
1606 * This may *change* the value of transaction_t->t_datalist, so anyone
1607 * who looks at t_datalist needs to lock against this function.
1608 *
1609 * Even worse, someone may be doing a journal_dirty_data on this
1610 * buffer. So we need to lock against that. journal_dirty_data()
1611 * will come out of the lock with the buffer dirty, which makes it
1612 * ineligible for release here.
1613 *
1614 * Who else is affected by this? hmm... Really the only contender
1615 * is do_get_write_access() - it could be looking at the buffer while
1616 * journal_try_to_free_buffer() is changing its state. But that
1617 * cannot happen because we never reallocate freed data as metadata
1618 * while the data is part of a transaction. Yes?
1619 */
1620int journal_try_to_free_buffers(journal_t *journal,
Al Viro27496a82005-10-21 03:20:48 -04001621 struct page *page, gfp_t unused_gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001622{
1623 struct buffer_head *head;
1624 struct buffer_head *bh;
1625 int ret = 0;
1626
1627 J_ASSERT(PageLocked(page));
1628
1629 head = page_buffers(page);
1630 bh = head;
1631 do {
1632 struct journal_head *jh;
1633
1634 /*
1635 * We take our own ref against the journal_head here to avoid
1636 * having to add tons of locking around each instance of
1637 * journal_remove_journal_head() and journal_put_journal_head().
1638 */
1639 jh = journal_grab_journal_head(bh);
1640 if (!jh)
1641 continue;
1642
1643 jbd_lock_bh_state(bh);
1644 __journal_try_to_free_buffer(journal, bh);
1645 journal_put_journal_head(jh);
1646 jbd_unlock_bh_state(bh);
1647 if (buffer_jbd(bh))
1648 goto busy;
1649 } while ((bh = bh->b_this_page) != head);
1650 ret = try_to_free_buffers(page);
1651busy:
1652 return ret;
1653}
1654
1655/*
1656 * This buffer is no longer needed. If it is on an older transaction's
1657 * checkpoint list we need to record it on this transaction's forget list
1658 * to pin this buffer (and hence its checkpointing transaction) down until
1659 * this transaction commits. If the buffer isn't on a checkpoint list, we
1660 * release it.
1661 * Returns non-zero if JBD no longer has an interest in the buffer.
1662 *
1663 * Called under j_list_lock.
1664 *
1665 * Called under jbd_lock_bh_state(bh).
1666 */
1667static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1668{
1669 int may_free = 1;
1670 struct buffer_head *bh = jh2bh(jh);
1671
1672 __journal_unfile_buffer(jh);
1673
1674 if (jh->b_cp_transaction) {
1675 JBUFFER_TRACE(jh, "on running+cp transaction");
1676 __journal_file_buffer(jh, transaction, BJ_Forget);
1677 clear_buffer_jbddirty(bh);
1678 may_free = 0;
1679 } else {
1680 JBUFFER_TRACE(jh, "on running transaction");
1681 journal_remove_journal_head(bh);
1682 __brelse(bh);
1683 }
1684 return may_free;
1685}
1686
1687/*
1688 * journal_invalidatepage
1689 *
1690 * This code is tricky. It has a number of cases to deal with.
1691 *
1692 * There are two invariants which this code relies on:
1693 *
1694 * i_size must be updated on disk before we start calling invalidatepage on the
1695 * data.
1696 *
1697 * This is done in ext3 by defining an ext3_setattr method which
1698 * updates i_size before truncate gets going. By maintaining this
1699 * invariant, we can be sure that it is safe to throw away any buffers
1700 * attached to the current transaction: once the transaction commits,
1701 * we know that the data will not be needed.
1702 *
1703 * Note however that we can *not* throw away data belonging to the
1704 * previous, committing transaction!
1705 *
1706 * Any disk blocks which *are* part of the previous, committing
1707 * transaction (and which therefore cannot be discarded immediately) are
1708 * not going to be reused in the new running transaction
1709 *
1710 * The bitmap committed_data images guarantee this: any block which is
1711 * allocated in one transaction and removed in the next will be marked
1712 * as in-use in the committed_data bitmap, so cannot be reused until
1713 * the next transaction to delete the block commits. This means that
1714 * leaving committing buffers dirty is quite safe: the disk blocks
1715 * cannot be reallocated to a different file and so buffer aliasing is
1716 * not possible.
1717 *
1718 *
1719 * The above applies mainly to ordered data mode. In writeback mode we
1720 * don't make guarantees about the order in which data hits disk --- in
1721 * particular we don't guarantee that new dirty data is flushed before
1722 * transaction commit --- so it is always safe just to discard data
1723 * immediately in that mode. --sct
1724 */
1725
1726/*
1727 * The journal_unmap_buffer helper function returns zero if the buffer
1728 * concerned remains pinned as an anonymous buffer belonging to an older
1729 * transaction.
1730 *
1731 * We're outside-transaction here. Either or both of j_running_transaction
1732 * and j_committing_transaction may be NULL.
1733 */
1734static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1735{
1736 transaction_t *transaction;
1737 struct journal_head *jh;
1738 int may_free = 1;
1739 int ret;
1740
1741 BUFFER_TRACE(bh, "entry");
1742
1743 /*
1744 * It is safe to proceed here without the j_list_lock because the
1745 * buffers cannot be stolen by try_to_free_buffers as long as we are
1746 * holding the page lock. --sct
1747 */
1748
1749 if (!buffer_jbd(bh))
1750 goto zap_buffer_unlocked;
1751
1752 spin_lock(&journal->j_state_lock);
1753 jbd_lock_bh_state(bh);
1754 spin_lock(&journal->j_list_lock);
1755
1756 jh = journal_grab_journal_head(bh);
1757 if (!jh)
1758 goto zap_buffer_no_jh;
1759
1760 transaction = jh->b_transaction;
1761 if (transaction == NULL) {
1762 /* First case: not on any transaction. If it
1763 * has no checkpoint link, then we can zap it:
1764 * it's a writeback-mode buffer so we don't care
1765 * if it hits disk safely. */
1766 if (!jh->b_cp_transaction) {
1767 JBUFFER_TRACE(jh, "not on any transaction: zap");
1768 goto zap_buffer;
1769 }
1770
1771 if (!buffer_dirty(bh)) {
1772 /* bdflush has written it. We can drop it now */
1773 goto zap_buffer;
1774 }
1775
1776 /* OK, it must be in the journal but still not
1777 * written fully to disk: it's metadata or
1778 * journaled data... */
1779
1780 if (journal->j_running_transaction) {
1781 /* ... and once the current transaction has
1782 * committed, the buffer won't be needed any
1783 * longer. */
1784 JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1785 ret = __dispose_buffer(jh,
1786 journal->j_running_transaction);
1787 journal_put_journal_head(jh);
1788 spin_unlock(&journal->j_list_lock);
1789 jbd_unlock_bh_state(bh);
1790 spin_unlock(&journal->j_state_lock);
1791 return ret;
1792 } else {
1793 /* There is no currently-running transaction. So the
1794 * orphan record which we wrote for this file must have
1795 * passed into commit. We must attach this buffer to
1796 * the committing transaction, if it exists. */
1797 if (journal->j_committing_transaction) {
1798 JBUFFER_TRACE(jh, "give to committing trans");
1799 ret = __dispose_buffer(jh,
1800 journal->j_committing_transaction);
1801 journal_put_journal_head(jh);
1802 spin_unlock(&journal->j_list_lock);
1803 jbd_unlock_bh_state(bh);
1804 spin_unlock(&journal->j_state_lock);
1805 return ret;
1806 } else {
1807 /* The orphan record's transaction has
1808 * committed. We can cleanse this buffer */
1809 clear_buffer_jbddirty(bh);
1810 goto zap_buffer;
1811 }
1812 }
1813 } else if (transaction == journal->j_committing_transaction) {
akpm@osdl.orgd13df842005-04-16 15:26:36 -07001814 if (jh->b_jlist == BJ_Locked) {
1815 /*
1816 * The buffer is on the committing transaction's locked
1817 * list. We have the buffer locked, so I/O has
1818 * completed. So we can nail the buffer now.
1819 */
1820 may_free = __dispose_buffer(jh, transaction);
1821 goto zap_buffer;
1822 }
1823 /*
1824 * If it is committing, we simply cannot touch it. We
Linus Torvalds1da177e2005-04-16 15:20:36 -07001825 * can remove it's next_transaction pointer from the
1826 * running transaction if that is set, but nothing
1827 * else. */
1828 JBUFFER_TRACE(jh, "on committing transaction");
1829 set_buffer_freed(bh);
1830 if (jh->b_next_transaction) {
1831 J_ASSERT(jh->b_next_transaction ==
1832 journal->j_running_transaction);
1833 jh->b_next_transaction = NULL;
1834 }
1835 journal_put_journal_head(jh);
1836 spin_unlock(&journal->j_list_lock);
1837 jbd_unlock_bh_state(bh);
1838 spin_unlock(&journal->j_state_lock);
1839 return 0;
1840 } else {
1841 /* Good, the buffer belongs to the running transaction.
1842 * We are writing our own transaction's data, not any
1843 * previous one's, so it is safe to throw it away
1844 * (remember that we expect the filesystem to have set
1845 * i_size already for this truncate so recovery will not
1846 * expose the disk blocks we are discarding here.) */
1847 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
1848 may_free = __dispose_buffer(jh, transaction);
1849 }
1850
1851zap_buffer:
1852 journal_put_journal_head(jh);
1853zap_buffer_no_jh:
1854 spin_unlock(&journal->j_list_lock);
1855 jbd_unlock_bh_state(bh);
1856 spin_unlock(&journal->j_state_lock);
1857zap_buffer_unlocked:
1858 clear_buffer_dirty(bh);
1859 J_ASSERT_BH(bh, !buffer_jbddirty(bh));
1860 clear_buffer_mapped(bh);
1861 clear_buffer_req(bh);
1862 clear_buffer_new(bh);
1863 bh->b_bdev = NULL;
1864 return may_free;
1865}
1866
1867/**
1868 * int journal_invalidatepage()
1869 * @journal: journal to use for flush...
1870 * @page: page to flush
1871 * @offset: length of page to invalidate.
1872 *
1873 * Reap page buffers containing data after offset in page.
1874 *
1875 * Return non-zero if the page's buffers were successfully reaped.
1876 */
1877int journal_invalidatepage(journal_t *journal,
1878 struct page *page,
1879 unsigned long offset)
1880{
1881 struct buffer_head *head, *bh, *next;
1882 unsigned int curr_off = 0;
1883 int may_free = 1;
1884
1885 if (!PageLocked(page))
1886 BUG();
1887 if (!page_has_buffers(page))
1888 return 1;
1889
1890 /* We will potentially be playing with lists other than just the
1891 * data lists (especially for journaled data mode), so be
1892 * cautious in our locking. */
1893
1894 head = bh = page_buffers(page);
1895 do {
1896 unsigned int next_off = curr_off + bh->b_size;
1897 next = bh->b_this_page;
1898
Linus Torvalds1da177e2005-04-16 15:20:36 -07001899 if (offset <= curr_off) {
1900 /* This block is wholly outside the truncation point */
1901 lock_buffer(bh);
1902 may_free &= journal_unmap_buffer(journal, bh);
1903 unlock_buffer(bh);
1904 }
1905 curr_off = next_off;
1906 bh = next;
1907
1908 } while (bh != head);
1909
1910 if (!offset) {
1911 if (!may_free || !try_to_free_buffers(page))
1912 return 0;
1913 J_ASSERT(!page_has_buffers(page));
1914 }
1915 return 1;
1916}
1917
1918/*
1919 * File a buffer on the given transaction list.
1920 */
1921void __journal_file_buffer(struct journal_head *jh,
1922 transaction_t *transaction, int jlist)
1923{
1924 struct journal_head **list = NULL;
1925 int was_dirty = 0;
1926 struct buffer_head *bh = jh2bh(jh);
1927
1928 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1929 assert_spin_locked(&transaction->t_journal->j_list_lock);
1930
1931 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1932 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
1933 jh->b_transaction == 0);
1934
1935 if (jh->b_transaction && jh->b_jlist == jlist)
1936 return;
1937
1938 /* The following list of buffer states needs to be consistent
1939 * with __jbd_unexpected_dirty_buffer()'s handling of dirty
1940 * state. */
1941
1942 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
1943 jlist == BJ_Shadow || jlist == BJ_Forget) {
1944 if (test_clear_buffer_dirty(bh) ||
1945 test_clear_buffer_jbddirty(bh))
1946 was_dirty = 1;
1947 }
1948
1949 if (jh->b_transaction)
1950 __journal_temp_unlink_buffer(jh);
1951 jh->b_transaction = transaction;
1952
1953 switch (jlist) {
1954 case BJ_None:
1955 J_ASSERT_JH(jh, !jh->b_committed_data);
1956 J_ASSERT_JH(jh, !jh->b_frozen_data);
1957 return;
1958 case BJ_SyncData:
1959 list = &transaction->t_sync_datalist;
1960 break;
1961 case BJ_Metadata:
1962 transaction->t_nr_buffers++;
1963 list = &transaction->t_buffers;
1964 break;
1965 case BJ_Forget:
1966 list = &transaction->t_forget;
1967 break;
1968 case BJ_IO:
1969 list = &transaction->t_iobuf_list;
1970 break;
1971 case BJ_Shadow:
1972 list = &transaction->t_shadow_list;
1973 break;
1974 case BJ_LogCtl:
1975 list = &transaction->t_log_list;
1976 break;
1977 case BJ_Reserved:
1978 list = &transaction->t_reserved_list;
1979 break;
1980 case BJ_Locked:
1981 list = &transaction->t_locked_list;
1982 break;
1983 }
1984
1985 __blist_add_buffer(list, jh);
1986 jh->b_jlist = jlist;
1987
1988 if (was_dirty)
1989 set_buffer_jbddirty(bh);
1990}
1991
1992void journal_file_buffer(struct journal_head *jh,
1993 transaction_t *transaction, int jlist)
1994{
1995 jbd_lock_bh_state(jh2bh(jh));
1996 spin_lock(&transaction->t_journal->j_list_lock);
1997 __journal_file_buffer(jh, transaction, jlist);
1998 spin_unlock(&transaction->t_journal->j_list_lock);
1999 jbd_unlock_bh_state(jh2bh(jh));
2000}
2001
2002/*
2003 * Remove a buffer from its current buffer list in preparation for
2004 * dropping it from its current transaction entirely. If the buffer has
2005 * already started to be used by a subsequent transaction, refile the
2006 * buffer on that transaction's metadata list.
2007 *
2008 * Called under journal->j_list_lock
2009 *
2010 * Called under jbd_lock_bh_state(jh2bh(jh))
2011 */
2012void __journal_refile_buffer(struct journal_head *jh)
2013{
2014 int was_dirty;
2015 struct buffer_head *bh = jh2bh(jh);
2016
2017 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2018 if (jh->b_transaction)
2019 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2020
2021 /* If the buffer is now unused, just drop it. */
2022 if (jh->b_next_transaction == NULL) {
2023 __journal_unfile_buffer(jh);
2024 return;
2025 }
2026
2027 /*
2028 * It has been modified by a later transaction: add it to the new
2029 * transaction's metadata list.
2030 */
2031
2032 was_dirty = test_clear_buffer_jbddirty(bh);
2033 __journal_temp_unlink_buffer(jh);
2034 jh->b_transaction = jh->b_next_transaction;
2035 jh->b_next_transaction = NULL;
2036 __journal_file_buffer(jh, jh->b_transaction, BJ_Metadata);
2037 J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2038
2039 if (was_dirty)
2040 set_buffer_jbddirty(bh);
2041}
2042
2043/*
2044 * For the unlocked version of this call, also make sure that any
2045 * hanging journal_head is cleaned up if necessary.
2046 *
2047 * __journal_refile_buffer is usually called as part of a single locked
2048 * operation on a buffer_head, in which the caller is probably going to
2049 * be hooking the journal_head onto other lists. In that case it is up
2050 * to the caller to remove the journal_head if necessary. For the
2051 * unlocked journal_refile_buffer call, the caller isn't going to be
2052 * doing anything else to the buffer so we need to do the cleanup
2053 * ourselves to avoid a jh leak.
2054 *
2055 * *** The journal_head may be freed by this call! ***
2056 */
2057void journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2058{
2059 struct buffer_head *bh = jh2bh(jh);
2060
2061 jbd_lock_bh_state(bh);
2062 spin_lock(&journal->j_list_lock);
2063
2064 __journal_refile_buffer(jh);
2065 jbd_unlock_bh_state(bh);
2066 journal_remove_journal_head(bh);
2067
2068 spin_unlock(&journal->j_list_lock);
2069 __brelse(bh);
2070}