aboutsummaryrefslogtreecommitdiffstats
path: root/fs/jbd/transaction.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/jbd/transaction.c')
-rw-r--r--fs/jbd/transaction.c2062
1 files changed, 2062 insertions, 0 deletions
diff --git a/fs/jbd/transaction.c b/fs/jbd/transaction.c
new file mode 100644
index 000000000000..932e7c1ef4a1
--- /dev/null
+++ b/fs/jbd/transaction.c
@@ -0,0 +1,2062 @@
1/*
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:
230 if (new_transaction)
231 kfree(new_transaction);
232 return ret;
233}
234
235/* Allocate a new handle. This should probably be in a slab... */
236static handle_t *new_handle(int nblocks)
237{
238 handle_t *handle = jbd_alloc_handle(GFP_NOFS);
239 if (!handle)
240 return NULL;
241 memset(handle, 0, sizeof(*handle));
242 handle->h_buffer_credits = nblocks;
243 handle->h_ref = 1;
244
245 return handle;
246}
247
248/**
249 * handle_t *journal_start() - Obtain a new handle.
250 * @journal: Journal to start transaction on.
251 * @nblocks: number of block buffer we might modify
252 *
253 * We make sure that the transaction can guarantee at least nblocks of
254 * modified buffers in the log. We block until the log can guarantee
255 * that much space.
256 *
257 * This function is visible to journal users (like ext3fs), so is not
258 * called with the journal already locked.
259 *
260 * Return a pointer to a newly allocated handle, or NULL on failure
261 */
262handle_t *journal_start(journal_t *journal, int nblocks)
263{
264 handle_t *handle = journal_current_handle();
265 int err;
266
267 if (!journal)
268 return ERR_PTR(-EROFS);
269
270 if (handle) {
271 J_ASSERT(handle->h_transaction->t_journal == journal);
272 handle->h_ref++;
273 return handle;
274 }
275
276 handle = new_handle(nblocks);
277 if (!handle)
278 return ERR_PTR(-ENOMEM);
279
280 current->journal_info = handle;
281
282 err = start_this_handle(journal, handle);
283 if (err < 0) {
284 jbd_free_handle(handle);
285 current->journal_info = NULL;
286 handle = ERR_PTR(err);
287 }
288 return handle;
289}
290
291/**
292 * int journal_extend() - extend buffer credits.
293 * @handle: handle to 'extend'
294 * @nblocks: nr blocks to try to extend by.
295 *
296 * Some transactions, such as large extends and truncates, can be done
297 * atomically all at once or in several stages. The operation requests
298 * a credit for a number of buffer modications in advance, but can
299 * extend its credit if it needs more.
300 *
301 * journal_extend tries to give the running handle more buffer credits.
302 * It does not guarantee that allocation - this is a best-effort only.
303 * The calling process MUST be able to deal cleanly with a failure to
304 * extend here.
305 *
306 * Return 0 on success, non-zero on failure.
307 *
308 * return code < 0 implies an error
309 * return code > 0 implies normal transaction-full status.
310 */
311int journal_extend(handle_t *handle, int nblocks)
312{
313 transaction_t *transaction = handle->h_transaction;
314 journal_t *journal = transaction->t_journal;
315 int result;
316 int wanted;
317
318 result = -EIO;
319 if (is_handle_aborted(handle))
320 goto out;
321
322 result = 1;
323
324 spin_lock(&journal->j_state_lock);
325
326 /* Don't extend a locked-down transaction! */
327 if (handle->h_transaction->t_state != T_RUNNING) {
328 jbd_debug(3, "denied handle %p %d blocks: "
329 "transaction not running\n", handle, nblocks);
330 goto error_out;
331 }
332
333 spin_lock(&transaction->t_handle_lock);
334 wanted = transaction->t_outstanding_credits + nblocks;
335
336 if (wanted > journal->j_max_transaction_buffers) {
337 jbd_debug(3, "denied handle %p %d blocks: "
338 "transaction too large\n", handle, nblocks);
339 goto unlock;
340 }
341
342 if (wanted > __log_space_left(journal)) {
343 jbd_debug(3, "denied handle %p %d blocks: "
344 "insufficient log space\n", handle, nblocks);
345 goto unlock;
346 }
347
348 handle->h_buffer_credits += nblocks;
349 transaction->t_outstanding_credits += nblocks;
350 result = 0;
351
352 jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
353unlock:
354 spin_unlock(&transaction->t_handle_lock);
355error_out:
356 spin_unlock(&journal->j_state_lock);
357out:
358 return result;
359}
360
361
362/**
363 * int journal_restart() - restart a handle .
364 * @handle: handle to restart
365 * @nblocks: nr credits requested
366 *
367 * Restart a handle for a multi-transaction filesystem
368 * operation.
369 *
370 * If the journal_extend() call above fails to grant new buffer credits
371 * to a running handle, a call to journal_restart will commit the
372 * handle's transaction so far and reattach the handle to a new
373 * transaction capabable of guaranteeing the requested number of
374 * credits.
375 */
376
377int journal_restart(handle_t *handle, int nblocks)
378{
379 transaction_t *transaction = handle->h_transaction;
380 journal_t *journal = transaction->t_journal;
381 int ret;
382
383 /* If we've had an abort of any type, don't even think about
384 * actually doing the restart! */
385 if (is_handle_aborted(handle))
386 return 0;
387
388 /*
389 * First unlink the handle from its current transaction, and start the
390 * commit on that.
391 */
392 J_ASSERT(transaction->t_updates > 0);
393 J_ASSERT(journal_current_handle() == handle);
394
395 spin_lock(&journal->j_state_lock);
396 spin_lock(&transaction->t_handle_lock);
397 transaction->t_outstanding_credits -= handle->h_buffer_credits;
398 transaction->t_updates--;
399
400 if (!transaction->t_updates)
401 wake_up(&journal->j_wait_updates);
402 spin_unlock(&transaction->t_handle_lock);
403
404 jbd_debug(2, "restarting handle %p\n", handle);
405 __log_start_commit(journal, transaction->t_tid);
406 spin_unlock(&journal->j_state_lock);
407
408 handle->h_buffer_credits = nblocks;
409 ret = start_this_handle(journal, handle);
410 return ret;
411}
412
413
414/**
415 * void journal_lock_updates () - establish a transaction barrier.
416 * @journal: Journal to establish a barrier on.
417 *
418 * This locks out any further updates from being started, and blocks
419 * until all existing updates have completed, returning only once the
420 * journal is in a quiescent state with no updates running.
421 *
422 * The journal lock should not be held on entry.
423 */
424void journal_lock_updates(journal_t *journal)
425{
426 DEFINE_WAIT(wait);
427
428 spin_lock(&journal->j_state_lock);
429 ++journal->j_barrier_count;
430
431 /* Wait until there are no running updates */
432 while (1) {
433 transaction_t *transaction = journal->j_running_transaction;
434
435 if (!transaction)
436 break;
437
438 spin_lock(&transaction->t_handle_lock);
439 if (!transaction->t_updates) {
440 spin_unlock(&transaction->t_handle_lock);
441 break;
442 }
443 prepare_to_wait(&journal->j_wait_updates, &wait,
444 TASK_UNINTERRUPTIBLE);
445 spin_unlock(&transaction->t_handle_lock);
446 spin_unlock(&journal->j_state_lock);
447 schedule();
448 finish_wait(&journal->j_wait_updates, &wait);
449 spin_lock(&journal->j_state_lock);
450 }
451 spin_unlock(&journal->j_state_lock);
452
453 /*
454 * We have now established a barrier against other normal updates, but
455 * we also need to barrier against other journal_lock_updates() calls
456 * to make sure that we serialise special journal-locked operations
457 * too.
458 */
459 down(&journal->j_barrier);
460}
461
462/**
463 * void journal_unlock_updates (journal_t* journal) - release barrier
464 * @journal: Journal to release the barrier on.
465 *
466 * Release a transaction barrier obtained with journal_lock_updates().
467 *
468 * Should be called without the journal lock held.
469 */
470void journal_unlock_updates (journal_t *journal)
471{
472 J_ASSERT(journal->j_barrier_count != 0);
473
474 up(&journal->j_barrier);
475 spin_lock(&journal->j_state_lock);
476 --journal->j_barrier_count;
477 spin_unlock(&journal->j_state_lock);
478 wake_up(&journal->j_wait_transaction_locked);
479}
480
481/*
482 * Report any unexpected dirty buffers which turn up. Normally those
483 * indicate an error, but they can occur if the user is running (say)
484 * tune2fs to modify the live filesystem, so we need the option of
485 * continuing as gracefully as possible. #
486 *
487 * The caller should already hold the journal lock and
488 * j_list_lock spinlock: most callers will need those anyway
489 * in order to probe the buffer's journaling state safely.
490 */
491static void jbd_unexpected_dirty_buffer(struct journal_head *jh)
492{
493 struct buffer_head *bh = jh2bh(jh);
494 int jlist;
495
496 if (buffer_dirty(bh)) {
497 /* If this buffer is one which might reasonably be dirty
498 * --- ie. data, or not part of this journal --- then
499 * we're OK to leave it alone, but otherwise we need to
500 * move the dirty bit to the journal's own internal
501 * JBDDirty bit. */
502 jlist = jh->b_jlist;
503
504 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
505 jlist == BJ_Shadow || jlist == BJ_Forget) {
506 if (test_clear_buffer_dirty(jh2bh(jh))) {
507 set_bit(BH_JBDDirty, &jh2bh(jh)->b_state);
508 }
509 }
510 }
511}
512
513/*
514 * If the buffer is already part of the current transaction, then there
515 * is nothing we need to do. If it is already part of a prior
516 * transaction which we are still committing to disk, then we need to
517 * make sure that we do not overwrite the old copy: we do copy-out to
518 * preserve the copy going to disk. We also account the buffer against
519 * the handle's metadata buffer credits (unless the buffer is already
520 * part of the transaction, that is).
521 *
522 */
523static int
524do_get_write_access(handle_t *handle, struct journal_head *jh,
525 int force_copy)
526{
527 struct buffer_head *bh;
528 transaction_t *transaction;
529 journal_t *journal;
530 int error;
531 char *frozen_buffer = NULL;
532 int need_copy = 0;
533
534 if (is_handle_aborted(handle))
535 return -EROFS;
536
537 transaction = handle->h_transaction;
538 journal = transaction->t_journal;
539
540 jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy);
541
542 JBUFFER_TRACE(jh, "entry");
543repeat:
544 bh = jh2bh(jh);
545
546 /* @@@ Need to check for errors here at some point. */
547
548 lock_buffer(bh);
549 jbd_lock_bh_state(bh);
550
551 /* We now hold the buffer lock so it is safe to query the buffer
552 * state. Is the buffer dirty?
553 *
554 * If so, there are two possibilities. The buffer may be
555 * non-journaled, and undergoing a quite legitimate writeback.
556 * Otherwise, it is journaled, and we don't expect dirty buffers
557 * in that state (the buffers should be marked JBD_Dirty
558 * instead.) So either the IO is being done under our own
559 * control and this is a bug, or it's a third party IO such as
560 * dump(8) (which may leave the buffer scheduled for read ---
561 * ie. locked but not dirty) or tune2fs (which may actually have
562 * the buffer dirtied, ugh.) */
563
564 if (buffer_dirty(bh)) {
565 /*
566 * First question: is this buffer already part of the current
567 * transaction or the existing committing transaction?
568 */
569 if (jh->b_transaction) {
570 J_ASSERT_JH(jh,
571 jh->b_transaction == transaction ||
572 jh->b_transaction ==
573 journal->j_committing_transaction);
574 if (jh->b_next_transaction)
575 J_ASSERT_JH(jh, jh->b_next_transaction ==
576 transaction);
577 JBUFFER_TRACE(jh, "Unexpected dirty buffer");
578 jbd_unexpected_dirty_buffer(jh);
579 }
580 }
581
582 unlock_buffer(bh);
583
584 error = -EROFS;
585 if (is_handle_aborted(handle)) {
586 jbd_unlock_bh_state(bh);
587 goto out;
588 }
589 error = 0;
590
591 /*
592 * The buffer is already part of this transaction if b_transaction or
593 * b_next_transaction points to it
594 */
595 if (jh->b_transaction == transaction ||
596 jh->b_next_transaction == transaction)
597 goto done;
598
599 /*
600 * If there is already a copy-out version of this buffer, then we don't
601 * need to make another one
602 */
603 if (jh->b_frozen_data) {
604 JBUFFER_TRACE(jh, "has frozen data");
605 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
606 jh->b_next_transaction = transaction;
607 goto done;
608 }
609
610 /* Is there data here we need to preserve? */
611
612 if (jh->b_transaction && jh->b_transaction != transaction) {
613 JBUFFER_TRACE(jh, "owned by older transaction");
614 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
615 J_ASSERT_JH(jh, jh->b_transaction ==
616 journal->j_committing_transaction);
617
618 /* There is one case we have to be very careful about.
619 * If the committing transaction is currently writing
620 * this buffer out to disk and has NOT made a copy-out,
621 * then we cannot modify the buffer contents at all
622 * right now. The essence of copy-out is that it is the
623 * extra copy, not the primary copy, which gets
624 * journaled. If the primary copy is already going to
625 * disk then we cannot do copy-out here. */
626
627 if (jh->b_jlist == BJ_Shadow) {
628 DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
629 wait_queue_head_t *wqh;
630
631 wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
632
633 JBUFFER_TRACE(jh, "on shadow: sleep");
634 jbd_unlock_bh_state(bh);
635 /* commit wakes up all shadow buffers after IO */
636 for ( ; ; ) {
637 prepare_to_wait(wqh, &wait.wait,
638 TASK_UNINTERRUPTIBLE);
639 if (jh->b_jlist != BJ_Shadow)
640 break;
641 schedule();
642 }
643 finish_wait(wqh, &wait.wait);
644 goto repeat;
645 }
646
647 /* Only do the copy if the currently-owning transaction
648 * still needs it. If it is on the Forget list, the
649 * committing transaction is past that stage. The
650 * buffer had better remain locked during the kmalloc,
651 * but that should be true --- we hold the journal lock
652 * still and the buffer is already on the BUF_JOURNAL
653 * list so won't be flushed.
654 *
655 * Subtle point, though: if this is a get_undo_access,
656 * then we will be relying on the frozen_data to contain
657 * the new value of the committed_data record after the
658 * transaction, so we HAVE to force the frozen_data copy
659 * in that case. */
660
661 if (jh->b_jlist != BJ_Forget || force_copy) {
662 JBUFFER_TRACE(jh, "generate frozen data");
663 if (!frozen_buffer) {
664 JBUFFER_TRACE(jh, "allocate memory for buffer");
665 jbd_unlock_bh_state(bh);
666 frozen_buffer = jbd_kmalloc(jh2bh(jh)->b_size,
667 GFP_NOFS);
668 if (!frozen_buffer) {
669 printk(KERN_EMERG
670 "%s: OOM for frozen_buffer\n",
671 __FUNCTION__);
672 JBUFFER_TRACE(jh, "oom!");
673 error = -ENOMEM;
674 jbd_lock_bh_state(bh);
675 goto done;
676 }
677 goto repeat;
678 }
679 jh->b_frozen_data = frozen_buffer;
680 frozen_buffer = NULL;
681 need_copy = 1;
682 }
683 jh->b_next_transaction = transaction;
684 }
685
686
687 /*
688 * Finally, if the buffer is not journaled right now, we need to make
689 * sure it doesn't get written to disk before the caller actually
690 * commits the new data
691 */
692 if (!jh->b_transaction) {
693 JBUFFER_TRACE(jh, "no transaction");
694 J_ASSERT_JH(jh, !jh->b_next_transaction);
695 jh->b_transaction = transaction;
696 JBUFFER_TRACE(jh, "file as BJ_Reserved");
697 spin_lock(&journal->j_list_lock);
698 __journal_file_buffer(jh, transaction, BJ_Reserved);
699 spin_unlock(&journal->j_list_lock);
700 }
701
702done:
703 if (need_copy) {
704 struct page *page;
705 int offset;
706 char *source;
707
708 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
709 "Possible IO failure.\n");
710 page = jh2bh(jh)->b_page;
711 offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK;
712 source = kmap_atomic(page, KM_USER0);
713 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
714 kunmap_atomic(source, KM_USER0);
715 }
716 jbd_unlock_bh_state(bh);
717
718 /*
719 * If we are about to journal a buffer, then any revoke pending on it is
720 * no longer valid
721 */
722 journal_cancel_revoke(handle, jh);
723
724out:
725 if (frozen_buffer)
726 kfree(frozen_buffer);
727
728 JBUFFER_TRACE(jh, "exit");
729 return error;
730}
731
732/**
733 * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
734 * @handle: transaction to add buffer modifications to
735 * @bh: bh to be used for metadata writes
736 * @credits: variable that will receive credits for the buffer
737 *
738 * Returns an error code or 0 on success.
739 *
740 * In full data journalling mode the buffer may be of type BJ_AsyncData,
741 * because we're write()ing a buffer which is also part of a shared mapping.
742 */
743
744int journal_get_write_access(handle_t *handle, struct buffer_head *bh)
745{
746 struct journal_head *jh = journal_add_journal_head(bh);
747 int rc;
748
749 /* We do not want to get caught playing with fields which the
750 * log thread also manipulates. Make sure that the buffer
751 * completes any outstanding IO before proceeding. */
752 rc = do_get_write_access(handle, jh, 0);
753 journal_put_journal_head(jh);
754 return rc;
755}
756
757
758/*
759 * When the user wants to journal a newly created buffer_head
760 * (ie. getblk() returned a new buffer and we are going to populate it
761 * manually rather than reading off disk), then we need to keep the
762 * buffer_head locked until it has been completely filled with new
763 * data. In this case, we should be able to make the assertion that
764 * the bh is not already part of an existing transaction.
765 *
766 * The buffer should already be locked by the caller by this point.
767 * There is no lock ranking violation: it was a newly created,
768 * unlocked buffer beforehand. */
769
770/**
771 * int journal_get_create_access () - notify intent to use newly created bh
772 * @handle: transaction to new buffer to
773 * @bh: new buffer.
774 *
775 * Call this if you create a new bh.
776 */
777int journal_get_create_access(handle_t *handle, struct buffer_head *bh)
778{
779 transaction_t *transaction = handle->h_transaction;
780 journal_t *journal = transaction->t_journal;
781 struct journal_head *jh = journal_add_journal_head(bh);
782 int err;
783
784 jbd_debug(5, "journal_head %p\n", jh);
785 err = -EROFS;
786 if (is_handle_aborted(handle))
787 goto out;
788 err = 0;
789
790 JBUFFER_TRACE(jh, "entry");
791 /*
792 * The buffer may already belong to this transaction due to pre-zeroing
793 * in the filesystem's new_block code. It may also be on the previous,
794 * committing transaction's lists, but it HAS to be in Forget state in
795 * that case: the transaction must have deleted the buffer for it to be
796 * reused here.
797 */
798 jbd_lock_bh_state(bh);
799 spin_lock(&journal->j_list_lock);
800 J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
801 jh->b_transaction == NULL ||
802 (jh->b_transaction == journal->j_committing_transaction &&
803 jh->b_jlist == BJ_Forget)));
804
805 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
806 J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
807
808 if (jh->b_transaction == NULL) {
809 jh->b_transaction = transaction;
810 JBUFFER_TRACE(jh, "file as BJ_Reserved");
811 __journal_file_buffer(jh, transaction, BJ_Reserved);
812 } else if (jh->b_transaction == journal->j_committing_transaction) {
813 JBUFFER_TRACE(jh, "set next transaction");
814 jh->b_next_transaction = transaction;
815 }
816 spin_unlock(&journal->j_list_lock);
817 jbd_unlock_bh_state(bh);
818
819 /*
820 * akpm: I added this. ext3_alloc_branch can pick up new indirect
821 * blocks which contain freed but then revoked metadata. We need
822 * to cancel the revoke in case we end up freeing it yet again
823 * and the reallocating as data - this would cause a second revoke,
824 * which hits an assertion error.
825 */
826 JBUFFER_TRACE(jh, "cancelling revoke");
827 journal_cancel_revoke(handle, jh);
828 journal_put_journal_head(jh);
829out:
830 return err;
831}
832
833/**
834 * int journal_get_undo_access() - Notify intent to modify metadata with
835 * non-rewindable consequences
836 * @handle: transaction
837 * @bh: buffer to undo
838 * @credits: store the number of taken credits here (if not NULL)
839 *
840 * Sometimes there is a need to distinguish between metadata which has
841 * been committed to disk and that which has not. The ext3fs code uses
842 * this for freeing and allocating space, we have to make sure that we
843 * do not reuse freed space until the deallocation has been committed,
844 * since if we overwrote that space we would make the delete
845 * un-rewindable in case of a crash.
846 *
847 * To deal with that, journal_get_undo_access requests write access to a
848 * buffer for parts of non-rewindable operations such as delete
849 * operations on the bitmaps. The journaling code must keep a copy of
850 * the buffer's contents prior to the undo_access call until such time
851 * as we know that the buffer has definitely been committed to disk.
852 *
853 * We never need to know which transaction the committed data is part
854 * of, buffers touched here are guaranteed to be dirtied later and so
855 * will be committed to a new transaction in due course, at which point
856 * we can discard the old committed data pointer.
857 *
858 * Returns error number or 0 on success.
859 */
860int journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
861{
862 int err;
863 struct journal_head *jh = journal_add_journal_head(bh);
864 char *committed_data = NULL;
865
866 JBUFFER_TRACE(jh, "entry");
867
868 /*
869 * Do this first --- it can drop the journal lock, so we want to
870 * make sure that obtaining the committed_data is done
871 * atomically wrt. completion of any outstanding commits.
872 */
873 err = do_get_write_access(handle, jh, 1);
874 if (err)
875 goto out;
876
877repeat:
878 if (!jh->b_committed_data) {
879 committed_data = jbd_kmalloc(jh2bh(jh)->b_size, GFP_NOFS);
880 if (!committed_data) {
881 printk(KERN_EMERG "%s: No memory for committed data\n",
882 __FUNCTION__);
883 err = -ENOMEM;
884 goto out;
885 }
886 }
887
888 jbd_lock_bh_state(bh);
889 if (!jh->b_committed_data) {
890 /* Copy out the current buffer contents into the
891 * preserved, committed copy. */
892 JBUFFER_TRACE(jh, "generate b_committed data");
893 if (!committed_data) {
894 jbd_unlock_bh_state(bh);
895 goto repeat;
896 }
897
898 jh->b_committed_data = committed_data;
899 committed_data = NULL;
900 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
901 }
902 jbd_unlock_bh_state(bh);
903out:
904 journal_put_journal_head(jh);
905 if (committed_data)
906 kfree(committed_data);
907 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;
1340 set_current_state(TASK_UNINTERRUPTIBLE);
1341 schedule_timeout(1);
1342 } while (old_handle_count != transaction->t_handle_count);
1343 }
1344
1345 current->journal_info = NULL;
1346 spin_lock(&journal->j_state_lock);
1347 spin_lock(&transaction->t_handle_lock);
1348 transaction->t_outstanding_credits -= handle->h_buffer_credits;
1349 transaction->t_updates--;
1350 if (!transaction->t_updates) {
1351 wake_up(&journal->j_wait_updates);
1352 if (journal->j_barrier_count)
1353 wake_up(&journal->j_wait_transaction_locked);
1354 }
1355
1356 /*
1357 * If the handle is marked SYNC, we need to set another commit
1358 * going! We also want to force a commit if the current
1359 * transaction is occupying too much of the log, or if the
1360 * transaction is too old now.
1361 */
1362 if (handle->h_sync ||
1363 transaction->t_outstanding_credits >
1364 journal->j_max_transaction_buffers ||
1365 time_after_eq(jiffies, transaction->t_expires)) {
1366 /* Do this even for aborted journals: an abort still
1367 * completes the commit thread, it just doesn't write
1368 * anything to disk. */
1369 tid_t tid = transaction->t_tid;
1370
1371 spin_unlock(&transaction->t_handle_lock);
1372 jbd_debug(2, "transaction too old, requesting commit for "
1373 "handle %p\n", handle);
1374 /* This is non-blocking */
1375 __log_start_commit(journal, transaction->t_tid);
1376 spin_unlock(&journal->j_state_lock);
1377
1378 /*
1379 * Special case: JFS_SYNC synchronous updates require us
1380 * to wait for the commit to complete.
1381 */
1382 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1383 err = log_wait_commit(journal, tid);
1384 } else {
1385 spin_unlock(&transaction->t_handle_lock);
1386 spin_unlock(&journal->j_state_lock);
1387 }
1388
1389 jbd_free_handle(handle);
1390 return err;
1391}
1392
1393/**int journal_force_commit() - force any uncommitted transactions
1394 * @journal: journal to force
1395 *
1396 * For synchronous operations: force any uncommitted transactions
1397 * to disk. May seem kludgy, but it reuses all the handle batching
1398 * code in a very simple manner.
1399 */
1400int journal_force_commit(journal_t *journal)
1401{
1402 handle_t *handle;
1403 int ret;
1404
1405 handle = journal_start(journal, 1);
1406 if (IS_ERR(handle)) {
1407 ret = PTR_ERR(handle);
1408 } else {
1409 handle->h_sync = 1;
1410 ret = journal_stop(handle);
1411 }
1412 return ret;
1413}
1414
1415/*
1416 *
1417 * List management code snippets: various functions for manipulating the
1418 * transaction buffer lists.
1419 *
1420 */
1421
1422/*
1423 * Append a buffer to a transaction list, given the transaction's list head
1424 * pointer.
1425 *
1426 * j_list_lock is held.
1427 *
1428 * jbd_lock_bh_state(jh2bh(jh)) is held.
1429 */
1430
1431static inline void
1432__blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1433{
1434 if (!*list) {
1435 jh->b_tnext = jh->b_tprev = jh;
1436 *list = jh;
1437 } else {
1438 /* Insert at the tail of the list to preserve order */
1439 struct journal_head *first = *list, *last = first->b_tprev;
1440 jh->b_tprev = last;
1441 jh->b_tnext = first;
1442 last->b_tnext = first->b_tprev = jh;
1443 }
1444}
1445
1446/*
1447 * Remove a buffer from a transaction list, given the transaction's list
1448 * head pointer.
1449 *
1450 * Called with j_list_lock held, and the journal may not be locked.
1451 *
1452 * jbd_lock_bh_state(jh2bh(jh)) is held.
1453 */
1454
1455static inline void
1456__blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1457{
1458 if (*list == jh) {
1459 *list = jh->b_tnext;
1460 if (*list == jh)
1461 *list = NULL;
1462 }
1463 jh->b_tprev->b_tnext = jh->b_tnext;
1464 jh->b_tnext->b_tprev = jh->b_tprev;
1465}
1466
1467/*
1468 * Remove a buffer from the appropriate transaction list.
1469 *
1470 * Note that this function can *change* the value of
1471 * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
1472 * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller
1473 * is holding onto a copy of one of thee pointers, it could go bad.
1474 * Generally the caller needs to re-read the pointer from the transaction_t.
1475 *
1476 * Called under j_list_lock. The journal may not be locked.
1477 */
1478void __journal_temp_unlink_buffer(struct journal_head *jh)
1479{
1480 struct journal_head **list = NULL;
1481 transaction_t *transaction;
1482 struct buffer_head *bh = jh2bh(jh);
1483
1484 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1485 transaction = jh->b_transaction;
1486 if (transaction)
1487 assert_spin_locked(&transaction->t_journal->j_list_lock);
1488
1489 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1490 if (jh->b_jlist != BJ_None)
1491 J_ASSERT_JH(jh, transaction != 0);
1492
1493 switch (jh->b_jlist) {
1494 case BJ_None:
1495 return;
1496 case BJ_SyncData:
1497 list = &transaction->t_sync_datalist;
1498 break;
1499 case BJ_Metadata:
1500 transaction->t_nr_buffers--;
1501 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1502 list = &transaction->t_buffers;
1503 break;
1504 case BJ_Forget:
1505 list = &transaction->t_forget;
1506 break;
1507 case BJ_IO:
1508 list = &transaction->t_iobuf_list;
1509 break;
1510 case BJ_Shadow:
1511 list = &transaction->t_shadow_list;
1512 break;
1513 case BJ_LogCtl:
1514 list = &transaction->t_log_list;
1515 break;
1516 case BJ_Reserved:
1517 list = &transaction->t_reserved_list;
1518 break;
1519 case BJ_Locked:
1520 list = &transaction->t_locked_list;
1521 break;
1522 }
1523
1524 __blist_del_buffer(list, jh);
1525 jh->b_jlist = BJ_None;
1526 if (test_clear_buffer_jbddirty(bh))
1527 mark_buffer_dirty(bh); /* Expose it to the VM */
1528}
1529
1530void __journal_unfile_buffer(struct journal_head *jh)
1531{
1532 __journal_temp_unlink_buffer(jh);
1533 jh->b_transaction = NULL;
1534}
1535
1536void journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1537{
1538 jbd_lock_bh_state(jh2bh(jh));
1539 spin_lock(&journal->j_list_lock);
1540 __journal_unfile_buffer(jh);
1541 spin_unlock(&journal->j_list_lock);
1542 jbd_unlock_bh_state(jh2bh(jh));
1543}
1544
1545/*
1546 * Called from journal_try_to_free_buffers().
1547 *
1548 * Called under jbd_lock_bh_state(bh)
1549 */
1550static void
1551__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1552{
1553 struct journal_head *jh;
1554
1555 jh = bh2jh(bh);
1556
1557 if (buffer_locked(bh) || buffer_dirty(bh))
1558 goto out;
1559
1560 if (jh->b_next_transaction != 0)
1561 goto out;
1562
1563 spin_lock(&journal->j_list_lock);
1564 if (jh->b_transaction != 0 && jh->b_cp_transaction == 0) {
1565 if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
1566 /* A written-back ordered data buffer */
1567 JBUFFER_TRACE(jh, "release data");
1568 __journal_unfile_buffer(jh);
1569 journal_remove_journal_head(bh);
1570 __brelse(bh);
1571 }
1572 } else if (jh->b_cp_transaction != 0 && jh->b_transaction == 0) {
1573 /* written-back checkpointed metadata buffer */
1574 if (jh->b_jlist == BJ_None) {
1575 JBUFFER_TRACE(jh, "remove from checkpoint list");
1576 __journal_remove_checkpoint(jh);
1577 journal_remove_journal_head(bh);
1578 __brelse(bh);
1579 }
1580 }
1581 spin_unlock(&journal->j_list_lock);
1582out:
1583 return;
1584}
1585
1586
1587/**
1588 * int journal_try_to_free_buffers() - try to free page buffers.
1589 * @journal: journal for operation
1590 * @page: to try and free
1591 * @unused_gfp_mask: unused
1592 *
1593 *
1594 * For all the buffers on this page,
1595 * if they are fully written out ordered data, move them onto BUF_CLEAN
1596 * so try_to_free_buffers() can reap them.
1597 *
1598 * This function returns non-zero if we wish try_to_free_buffers()
1599 * to be called. We do this if the page is releasable by try_to_free_buffers().
1600 * We also do it if the page has locked or dirty buffers and the caller wants
1601 * us to perform sync or async writeout.
1602 *
1603 * This complicates JBD locking somewhat. We aren't protected by the
1604 * BKL here. We wish to remove the buffer from its committing or
1605 * running transaction's ->t_datalist via __journal_unfile_buffer.
1606 *
1607 * This may *change* the value of transaction_t->t_datalist, so anyone
1608 * who looks at t_datalist needs to lock against this function.
1609 *
1610 * Even worse, someone may be doing a journal_dirty_data on this
1611 * buffer. So we need to lock against that. journal_dirty_data()
1612 * will come out of the lock with the buffer dirty, which makes it
1613 * ineligible for release here.
1614 *
1615 * Who else is affected by this? hmm... Really the only contender
1616 * is do_get_write_access() - it could be looking at the buffer while
1617 * journal_try_to_free_buffer() is changing its state. But that
1618 * cannot happen because we never reallocate freed data as metadata
1619 * while the data is part of a transaction. Yes?
1620 */
1621int journal_try_to_free_buffers(journal_t *journal,
1622 struct page *page, int unused_gfp_mask)
1623{
1624 struct buffer_head *head;
1625 struct buffer_head *bh;
1626 int ret = 0;
1627
1628 J_ASSERT(PageLocked(page));
1629
1630 head = page_buffers(page);
1631 bh = head;
1632 do {
1633 struct journal_head *jh;
1634
1635 /*
1636 * We take our own ref against the journal_head here to avoid
1637 * having to add tons of locking around each instance of
1638 * journal_remove_journal_head() and journal_put_journal_head().
1639 */
1640 jh = journal_grab_journal_head(bh);
1641 if (!jh)
1642 continue;
1643
1644 jbd_lock_bh_state(bh);
1645 __journal_try_to_free_buffer(journal, bh);
1646 journal_put_journal_head(jh);
1647 jbd_unlock_bh_state(bh);
1648 if (buffer_jbd(bh))
1649 goto busy;
1650 } while ((bh = bh->b_this_page) != head);
1651 ret = try_to_free_buffers(page);
1652busy:
1653 return ret;
1654}
1655
1656/*
1657 * This buffer is no longer needed. If it is on an older transaction's
1658 * checkpoint list we need to record it on this transaction's forget list
1659 * to pin this buffer (and hence its checkpointing transaction) down until
1660 * this transaction commits. If the buffer isn't on a checkpoint list, we
1661 * release it.
1662 * Returns non-zero if JBD no longer has an interest in the buffer.
1663 *
1664 * Called under j_list_lock.
1665 *
1666 * Called under jbd_lock_bh_state(bh).
1667 */
1668static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1669{
1670 int may_free = 1;
1671 struct buffer_head *bh = jh2bh(jh);
1672
1673 __journal_unfile_buffer(jh);
1674
1675 if (jh->b_cp_transaction) {
1676 JBUFFER_TRACE(jh, "on running+cp transaction");
1677 __journal_file_buffer(jh, transaction, BJ_Forget);
1678 clear_buffer_jbddirty(bh);
1679 may_free = 0;
1680 } else {
1681 JBUFFER_TRACE(jh, "on running transaction");
1682 journal_remove_journal_head(bh);
1683 __brelse(bh);
1684 }
1685 return may_free;
1686}
1687
1688/*
1689 * journal_invalidatepage
1690 *
1691 * This code is tricky. It has a number of cases to deal with.
1692 *
1693 * There are two invariants which this code relies on:
1694 *
1695 * i_size must be updated on disk before we start calling invalidatepage on the
1696 * data.
1697 *
1698 * This is done in ext3 by defining an ext3_setattr method which
1699 * updates i_size before truncate gets going. By maintaining this
1700 * invariant, we can be sure that it is safe to throw away any buffers
1701 * attached to the current transaction: once the transaction commits,
1702 * we know that the data will not be needed.
1703 *
1704 * Note however that we can *not* throw away data belonging to the
1705 * previous, committing transaction!
1706 *
1707 * Any disk blocks which *are* part of the previous, committing
1708 * transaction (and which therefore cannot be discarded immediately) are
1709 * not going to be reused in the new running transaction
1710 *
1711 * The bitmap committed_data images guarantee this: any block which is
1712 * allocated in one transaction and removed in the next will be marked
1713 * as in-use in the committed_data bitmap, so cannot be reused until
1714 * the next transaction to delete the block commits. This means that
1715 * leaving committing buffers dirty is quite safe: the disk blocks
1716 * cannot be reallocated to a different file and so buffer aliasing is
1717 * not possible.
1718 *
1719 *
1720 * The above applies mainly to ordered data mode. In writeback mode we
1721 * don't make guarantees about the order in which data hits disk --- in
1722 * particular we don't guarantee that new dirty data is flushed before
1723 * transaction commit --- so it is always safe just to discard data
1724 * immediately in that mode. --sct
1725 */
1726
1727/*
1728 * The journal_unmap_buffer helper function returns zero if the buffer
1729 * concerned remains pinned as an anonymous buffer belonging to an older
1730 * transaction.
1731 *
1732 * We're outside-transaction here. Either or both of j_running_transaction
1733 * and j_committing_transaction may be NULL.
1734 */
1735static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1736{
1737 transaction_t *transaction;
1738 struct journal_head *jh;
1739 int may_free = 1;
1740 int ret;
1741
1742 BUFFER_TRACE(bh, "entry");
1743
1744 /*
1745 * It is safe to proceed here without the j_list_lock because the
1746 * buffers cannot be stolen by try_to_free_buffers as long as we are
1747 * holding the page lock. --sct
1748 */
1749
1750 if (!buffer_jbd(bh))
1751 goto zap_buffer_unlocked;
1752
1753 spin_lock(&journal->j_state_lock);
1754 jbd_lock_bh_state(bh);
1755 spin_lock(&journal->j_list_lock);
1756
1757 jh = journal_grab_journal_head(bh);
1758 if (!jh)
1759 goto zap_buffer_no_jh;
1760
1761 transaction = jh->b_transaction;
1762 if (transaction == NULL) {
1763 /* First case: not on any transaction. If it
1764 * has no checkpoint link, then we can zap it:
1765 * it's a writeback-mode buffer so we don't care
1766 * if it hits disk safely. */
1767 if (!jh->b_cp_transaction) {
1768 JBUFFER_TRACE(jh, "not on any transaction: zap");
1769 goto zap_buffer;
1770 }
1771
1772 if (!buffer_dirty(bh)) {
1773 /* bdflush has written it. We can drop it now */
1774 goto zap_buffer;
1775 }
1776
1777 /* OK, it must be in the journal but still not
1778 * written fully to disk: it's metadata or
1779 * journaled data... */
1780
1781 if (journal->j_running_transaction) {
1782 /* ... and once the current transaction has
1783 * committed, the buffer won't be needed any
1784 * longer. */
1785 JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1786 ret = __dispose_buffer(jh,
1787 journal->j_running_transaction);
1788 journal_put_journal_head(jh);
1789 spin_unlock(&journal->j_list_lock);
1790 jbd_unlock_bh_state(bh);
1791 spin_unlock(&journal->j_state_lock);
1792 return ret;
1793 } else {
1794 /* There is no currently-running transaction. So the
1795 * orphan record which we wrote for this file must have
1796 * passed into commit. We must attach this buffer to
1797 * the committing transaction, if it exists. */
1798 if (journal->j_committing_transaction) {
1799 JBUFFER_TRACE(jh, "give to committing trans");
1800 ret = __dispose_buffer(jh,
1801 journal->j_committing_transaction);
1802 journal_put_journal_head(jh);
1803 spin_unlock(&journal->j_list_lock);
1804 jbd_unlock_bh_state(bh);
1805 spin_unlock(&journal->j_state_lock);
1806 return ret;
1807 } else {
1808 /* The orphan record's transaction has
1809 * committed. We can cleanse this buffer */
1810 clear_buffer_jbddirty(bh);
1811 goto zap_buffer;
1812 }
1813 }
1814 } else if (transaction == journal->j_committing_transaction) {
1815 /* If it is committing, we simply cannot touch it. We
1816 * can remove it's next_transaction pointer from the
1817 * running transaction if that is set, but nothing
1818 * else. */
1819 JBUFFER_TRACE(jh, "on committing transaction");
1820 set_buffer_freed(bh);
1821 if (jh->b_next_transaction) {
1822 J_ASSERT(jh->b_next_transaction ==
1823 journal->j_running_transaction);
1824 jh->b_next_transaction = NULL;
1825 }
1826 journal_put_journal_head(jh);
1827 spin_unlock(&journal->j_list_lock);
1828 jbd_unlock_bh_state(bh);
1829 spin_unlock(&journal->j_state_lock);
1830 return 0;
1831 } else {
1832 /* Good, the buffer belongs to the running transaction.
1833 * We are writing our own transaction's data, not any
1834 * previous one's, so it is safe to throw it away
1835 * (remember that we expect the filesystem to have set
1836 * i_size already for this truncate so recovery will not
1837 * expose the disk blocks we are discarding here.) */
1838 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
1839 may_free = __dispose_buffer(jh, transaction);
1840 }
1841
1842zap_buffer:
1843 journal_put_journal_head(jh);
1844zap_buffer_no_jh:
1845 spin_unlock(&journal->j_list_lock);
1846 jbd_unlock_bh_state(bh);
1847 spin_unlock(&journal->j_state_lock);
1848zap_buffer_unlocked:
1849 clear_buffer_dirty(bh);
1850 J_ASSERT_BH(bh, !buffer_jbddirty(bh));
1851 clear_buffer_mapped(bh);
1852 clear_buffer_req(bh);
1853 clear_buffer_new(bh);
1854 bh->b_bdev = NULL;
1855 return may_free;
1856}
1857
1858/**
1859 * int journal_invalidatepage()
1860 * @journal: journal to use for flush...
1861 * @page: page to flush
1862 * @offset: length of page to invalidate.
1863 *
1864 * Reap page buffers containing data after offset in page.
1865 *
1866 * Return non-zero if the page's buffers were successfully reaped.
1867 */
1868int journal_invalidatepage(journal_t *journal,
1869 struct page *page,
1870 unsigned long offset)
1871{
1872 struct buffer_head *head, *bh, *next;
1873 unsigned int curr_off = 0;
1874 int may_free = 1;
1875
1876 if (!PageLocked(page))
1877 BUG();
1878 if (!page_has_buffers(page))
1879 return 1;
1880
1881 /* We will potentially be playing with lists other than just the
1882 * data lists (especially for journaled data mode), so be
1883 * cautious in our locking. */
1884
1885 head = bh = page_buffers(page);
1886 do {
1887 unsigned int next_off = curr_off + bh->b_size;
1888 next = bh->b_this_page;
1889
1890 /* AKPM: doing lock_buffer here may be overly paranoid */
1891 if (offset <= curr_off) {
1892 /* This block is wholly outside the truncation point */
1893 lock_buffer(bh);
1894 may_free &= journal_unmap_buffer(journal, bh);
1895 unlock_buffer(bh);
1896 }
1897 curr_off = next_off;
1898 bh = next;
1899
1900 } while (bh != head);
1901
1902 if (!offset) {
1903 if (!may_free || !try_to_free_buffers(page))
1904 return 0;
1905 J_ASSERT(!page_has_buffers(page));
1906 }
1907 return 1;
1908}
1909
1910/*
1911 * File a buffer on the given transaction list.
1912 */
1913void __journal_file_buffer(struct journal_head *jh,
1914 transaction_t *transaction, int jlist)
1915{
1916 struct journal_head **list = NULL;
1917 int was_dirty = 0;
1918 struct buffer_head *bh = jh2bh(jh);
1919
1920 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1921 assert_spin_locked(&transaction->t_journal->j_list_lock);
1922
1923 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1924 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
1925 jh->b_transaction == 0);
1926
1927 if (jh->b_transaction && jh->b_jlist == jlist)
1928 return;
1929
1930 /* The following list of buffer states needs to be consistent
1931 * with __jbd_unexpected_dirty_buffer()'s handling of dirty
1932 * state. */
1933
1934 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
1935 jlist == BJ_Shadow || jlist == BJ_Forget) {
1936 if (test_clear_buffer_dirty(bh) ||
1937 test_clear_buffer_jbddirty(bh))
1938 was_dirty = 1;
1939 }
1940
1941 if (jh->b_transaction)
1942 __journal_temp_unlink_buffer(jh);
1943 jh->b_transaction = transaction;
1944
1945 switch (jlist) {
1946 case BJ_None:
1947 J_ASSERT_JH(jh, !jh->b_committed_data);
1948 J_ASSERT_JH(jh, !jh->b_frozen_data);
1949 return;
1950 case BJ_SyncData:
1951 list = &transaction->t_sync_datalist;
1952 break;
1953 case BJ_Metadata:
1954 transaction->t_nr_buffers++;
1955 list = &transaction->t_buffers;
1956 break;
1957 case BJ_Forget:
1958 list = &transaction->t_forget;
1959 break;
1960 case BJ_IO:
1961 list = &transaction->t_iobuf_list;
1962 break;
1963 case BJ_Shadow:
1964 list = &transaction->t_shadow_list;
1965 break;
1966 case BJ_LogCtl:
1967 list = &transaction->t_log_list;
1968 break;
1969 case BJ_Reserved:
1970 list = &transaction->t_reserved_list;
1971 break;
1972 case BJ_Locked:
1973 list = &transaction->t_locked_list;
1974 break;
1975 }
1976
1977 __blist_add_buffer(list, jh);
1978 jh->b_jlist = jlist;
1979
1980 if (was_dirty)
1981 set_buffer_jbddirty(bh);
1982}
1983
1984void journal_file_buffer(struct journal_head *jh,
1985 transaction_t *transaction, int jlist)
1986{
1987 jbd_lock_bh_state(jh2bh(jh));
1988 spin_lock(&transaction->t_journal->j_list_lock);
1989 __journal_file_buffer(jh, transaction, jlist);
1990 spin_unlock(&transaction->t_journal->j_list_lock);
1991 jbd_unlock_bh_state(jh2bh(jh));
1992}
1993
1994/*
1995 * Remove a buffer from its current buffer list in preparation for
1996 * dropping it from its current transaction entirely. If the buffer has
1997 * already started to be used by a subsequent transaction, refile the
1998 * buffer on that transaction's metadata list.
1999 *
2000 * Called under journal->j_list_lock
2001 *
2002 * Called under jbd_lock_bh_state(jh2bh(jh))
2003 */
2004void __journal_refile_buffer(struct journal_head *jh)
2005{
2006 int was_dirty;
2007 struct buffer_head *bh = jh2bh(jh);
2008
2009 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2010 if (jh->b_transaction)
2011 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2012
2013 /* If the buffer is now unused, just drop it. */
2014 if (jh->b_next_transaction == NULL) {
2015 __journal_unfile_buffer(jh);
2016 return;
2017 }
2018
2019 /*
2020 * It has been modified by a later transaction: add it to the new
2021 * transaction's metadata list.
2022 */
2023
2024 was_dirty = test_clear_buffer_jbddirty(bh);
2025 __journal_temp_unlink_buffer(jh);
2026 jh->b_transaction = jh->b_next_transaction;
2027 jh->b_next_transaction = NULL;
2028 __journal_file_buffer(jh, jh->b_transaction, BJ_Metadata);
2029 J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2030
2031 if (was_dirty)
2032 set_buffer_jbddirty(bh);
2033}
2034
2035/*
2036 * For the unlocked version of this call, also make sure that any
2037 * hanging journal_head is cleaned up if necessary.
2038 *
2039 * __journal_refile_buffer is usually called as part of a single locked
2040 * operation on a buffer_head, in which the caller is probably going to
2041 * be hooking the journal_head onto other lists. In that case it is up
2042 * to the caller to remove the journal_head if necessary. For the
2043 * unlocked journal_refile_buffer call, the caller isn't going to be
2044 * doing anything else to the buffer so we need to do the cleanup
2045 * ourselves to avoid a jh leak.
2046 *
2047 * *** The journal_head may be freed by this call! ***
2048 */
2049void journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2050{
2051 struct buffer_head *bh = jh2bh(jh);
2052
2053 jbd_lock_bh_state(bh);
2054 spin_lock(&journal->j_list_lock);
2055
2056 __journal_refile_buffer(jh);
2057 jbd_unlock_bh_state(bh);
2058 journal_remove_journal_head(bh);
2059
2060 spin_unlock(&journal->j_list_lock);
2061 __brelse(bh);
2062}
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-10 07:25:12 -0500