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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/transaction.c
Mingming Caoae6ddcc2006-09-27 01:49:27 -07003 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07004 * 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
Mingming Caoae6ddcc2006-09-27 01:49:27 -070013 * journaling system.
Linus Torvalds1da177e2005-04-16 15:20:36 -070014 *
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. */
Andrew Mortone3df1892006-03-25 03:06:53 -080056 journal->j_commit_timer.expires = transaction->t_expires;
57 add_timer(&journal->j_commit_timer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070058
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
Mingming Caoae6ddcc2006-09-27 01:49:27 -070077 * transaction's buffer credits.
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 */
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);
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700120 ret = -EROFS;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 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
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700185 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186 * 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
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700194 * in the new transaction.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 *
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:
Andrew Morton304c4c82006-06-23 02:05:31 -0700230 if (unlikely(new_transaction)) /* It's usually NULL */
231 kfree(new_transaction);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 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/**
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700249 * handle_t *journal_start() - Obtain a new handle.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 * @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
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700255 * that much space.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 *
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.
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700295 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 * 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
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700299 * extend its credit if it needs more.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 *
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
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700366 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 * 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 */
Arjan van de Ven2c68ee72006-03-23 03:00:35 -0800459 mutex_lock(&journal->j_barrier);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460}
461
462/**
463 * void journal_unlock_updates (journal_t* journal) - release barrier
464 * @journal: Journal to release the barrier on.
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700465 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 * 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
Arjan van de Ven2c68ee72006-03-23 03:00:35 -0800474 mutex_unlock(&journal->j_barrier);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475 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{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 int jlist;
494
Jan Kara4407c2b2005-09-06 15:19:17 -0700495 /* If this buffer is one which might reasonably be dirty
496 * --- ie. data, or not part of this journal --- then
497 * we're OK to leave it alone, but otherwise we need to
498 * move the dirty bit to the journal's own internal
499 * JBDDirty bit. */
500 jlist = jh->b_jlist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501
Jan Kara4407c2b2005-09-06 15:19:17 -0700502 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
503 jlist == BJ_Shadow || jlist == BJ_Forget) {
504 struct buffer_head *bh = jh2bh(jh);
505
506 if (test_clear_buffer_dirty(bh))
507 set_buffer_jbddirty(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 }
509}
510
511/*
512 * If the buffer is already part of the current transaction, then there
513 * is nothing we need to do. If it is already part of a prior
514 * transaction which we are still committing to disk, then we need to
515 * make sure that we do not overwrite the old copy: we do copy-out to
516 * preserve the copy going to disk. We also account the buffer against
517 * the handle's metadata buffer credits (unless the buffer is already
518 * part of the transaction, that is).
519 *
520 */
521static int
522do_get_write_access(handle_t *handle, struct journal_head *jh,
523 int force_copy)
524{
525 struct buffer_head *bh;
526 transaction_t *transaction;
527 journal_t *journal;
528 int error;
529 char *frozen_buffer = NULL;
530 int need_copy = 0;
531
532 if (is_handle_aborted(handle))
533 return -EROFS;
534
535 transaction = handle->h_transaction;
536 journal = transaction->t_journal;
537
538 jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy);
539
540 JBUFFER_TRACE(jh, "entry");
541repeat:
542 bh = jh2bh(jh);
543
544 /* @@@ Need to check for errors here at some point. */
545
546 lock_buffer(bh);
547 jbd_lock_bh_state(bh);
548
549 /* We now hold the buffer lock so it is safe to query the buffer
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700550 * state. Is the buffer dirty?
551 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552 * If so, there are two possibilities. The buffer may be
553 * non-journaled, and undergoing a quite legitimate writeback.
554 * Otherwise, it is journaled, and we don't expect dirty buffers
555 * in that state (the buffers should be marked JBD_Dirty
556 * instead.) So either the IO is being done under our own
557 * control and this is a bug, or it's a third party IO such as
558 * dump(8) (which may leave the buffer scheduled for read ---
559 * ie. locked but not dirty) or tune2fs (which may actually have
560 * the buffer dirtied, ugh.) */
561
562 if (buffer_dirty(bh)) {
563 /*
564 * First question: is this buffer already part of the current
565 * transaction or the existing committing transaction?
566 */
567 if (jh->b_transaction) {
568 J_ASSERT_JH(jh,
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700569 jh->b_transaction == transaction ||
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570 jh->b_transaction ==
571 journal->j_committing_transaction);
572 if (jh->b_next_transaction)
573 J_ASSERT_JH(jh, jh->b_next_transaction ==
574 transaction);
Jan Kara4407c2b2005-09-06 15:19:17 -0700575 }
576 /*
577 * In any case we need to clean the dirty flag and we must
578 * do it under the buffer lock to be sure we don't race
579 * with running write-out.
580 */
581 JBUFFER_TRACE(jh, "Unexpected dirty buffer");
582 jbd_unexpected_dirty_buffer(jh);
Dave Kleikampe9ad5622006-09-27 01:49:35 -0700583 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584
585 unlock_buffer(bh);
586
587 error = -EROFS;
588 if (is_handle_aborted(handle)) {
589 jbd_unlock_bh_state(bh);
590 goto out;
591 }
592 error = 0;
593
594 /*
595 * The buffer is already part of this transaction if b_transaction or
596 * b_next_transaction points to it
597 */
598 if (jh->b_transaction == transaction ||
599 jh->b_next_transaction == transaction)
600 goto done;
601
602 /*
603 * If there is already a copy-out version of this buffer, then we don't
604 * need to make another one
605 */
606 if (jh->b_frozen_data) {
607 JBUFFER_TRACE(jh, "has frozen data");
608 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
609 jh->b_next_transaction = transaction;
610 goto done;
611 }
612
613 /* Is there data here we need to preserve? */
614
615 if (jh->b_transaction && jh->b_transaction != transaction) {
616 JBUFFER_TRACE(jh, "owned by older transaction");
617 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
618 J_ASSERT_JH(jh, jh->b_transaction ==
619 journal->j_committing_transaction);
620
621 /* There is one case we have to be very careful about.
622 * If the committing transaction is currently writing
623 * this buffer out to disk and has NOT made a copy-out,
624 * then we cannot modify the buffer contents at all
625 * right now. The essence of copy-out is that it is the
626 * extra copy, not the primary copy, which gets
627 * journaled. If the primary copy is already going to
628 * disk then we cannot do copy-out here. */
629
630 if (jh->b_jlist == BJ_Shadow) {
631 DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
632 wait_queue_head_t *wqh;
633
634 wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
635
636 JBUFFER_TRACE(jh, "on shadow: sleep");
637 jbd_unlock_bh_state(bh);
638 /* commit wakes up all shadow buffers after IO */
639 for ( ; ; ) {
640 prepare_to_wait(wqh, &wait.wait,
641 TASK_UNINTERRUPTIBLE);
642 if (jh->b_jlist != BJ_Shadow)
643 break;
644 schedule();
645 }
646 finish_wait(wqh, &wait.wait);
647 goto repeat;
648 }
649
650 /* Only do the copy if the currently-owning transaction
651 * still needs it. If it is on the Forget list, the
652 * committing transaction is past that stage. The
653 * buffer had better remain locked during the kmalloc,
654 * but that should be true --- we hold the journal lock
655 * still and the buffer is already on the BUF_JOURNAL
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700656 * list so won't be flushed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657 *
658 * Subtle point, though: if this is a get_undo_access,
659 * then we will be relying on the frozen_data to contain
660 * the new value of the committed_data record after the
661 * transaction, so we HAVE to force the frozen_data copy
662 * in that case. */
663
664 if (jh->b_jlist != BJ_Forget || force_copy) {
665 JBUFFER_TRACE(jh, "generate frozen data");
666 if (!frozen_buffer) {
667 JBUFFER_TRACE(jh, "allocate memory for buffer");
668 jbd_unlock_bh_state(bh);
Badari Pulavartyea817392006-08-27 01:23:52 -0700669 frozen_buffer =
670 jbd_slab_alloc(jh2bh(jh)->b_size,
671 GFP_NOFS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672 if (!frozen_buffer) {
673 printk(KERN_EMERG
674 "%s: OOM for frozen_buffer\n",
675 __FUNCTION__);
676 JBUFFER_TRACE(jh, "oom!");
677 error = -ENOMEM;
678 jbd_lock_bh_state(bh);
679 goto done;
680 }
681 goto repeat;
682 }
683 jh->b_frozen_data = frozen_buffer;
684 frozen_buffer = NULL;
685 need_copy = 1;
686 }
687 jh->b_next_transaction = transaction;
688 }
689
690
691 /*
692 * Finally, if the buffer is not journaled right now, we need to make
693 * sure it doesn't get written to disk before the caller actually
694 * commits the new data
695 */
696 if (!jh->b_transaction) {
697 JBUFFER_TRACE(jh, "no transaction");
698 J_ASSERT_JH(jh, !jh->b_next_transaction);
699 jh->b_transaction = transaction;
700 JBUFFER_TRACE(jh, "file as BJ_Reserved");
701 spin_lock(&journal->j_list_lock);
702 __journal_file_buffer(jh, transaction, BJ_Reserved);
703 spin_unlock(&journal->j_list_lock);
704 }
705
706done:
707 if (need_copy) {
708 struct page *page;
709 int offset;
710 char *source;
711
712 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
713 "Possible IO failure.\n");
714 page = jh2bh(jh)->b_page;
715 offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK;
716 source = kmap_atomic(page, KM_USER0);
717 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
718 kunmap_atomic(source, KM_USER0);
719 }
720 jbd_unlock_bh_state(bh);
721
722 /*
723 * If we are about to journal a buffer, then any revoke pending on it is
724 * no longer valid
725 */
726 journal_cancel_revoke(handle, jh);
727
728out:
Andrew Morton304c4c82006-06-23 02:05:31 -0700729 if (unlikely(frozen_buffer)) /* It's usually NULL */
Badari Pulavarty4cfb04a2006-08-31 21:27:54 -0700730 jbd_slab_free(frozen_buffer, bh->b_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731
732 JBUFFER_TRACE(jh, "exit");
733 return error;
734}
735
736/**
737 * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
738 * @handle: transaction to add buffer modifications to
739 * @bh: bh to be used for metadata writes
740 * @credits: variable that will receive credits for the buffer
741 *
742 * Returns an error code or 0 on success.
743 *
744 * In full data journalling mode the buffer may be of type BJ_AsyncData,
745 * because we're write()ing a buffer which is also part of a shared mapping.
746 */
747
748int journal_get_write_access(handle_t *handle, struct buffer_head *bh)
749{
750 struct journal_head *jh = journal_add_journal_head(bh);
751 int rc;
752
753 /* We do not want to get caught playing with fields which the
754 * log thread also manipulates. Make sure that the buffer
755 * completes any outstanding IO before proceeding. */
756 rc = do_get_write_access(handle, jh, 0);
757 journal_put_journal_head(jh);
758 return rc;
759}
760
761
762/*
763 * When the user wants to journal a newly created buffer_head
764 * (ie. getblk() returned a new buffer and we are going to populate it
765 * manually rather than reading off disk), then we need to keep the
766 * buffer_head locked until it has been completely filled with new
767 * data. In this case, we should be able to make the assertion that
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700768 * the bh is not already part of an existing transaction.
769 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770 * The buffer should already be locked by the caller by this point.
771 * There is no lock ranking violation: it was a newly created,
772 * unlocked buffer beforehand. */
773
774/**
775 * int journal_get_create_access () - notify intent to use newly created bh
776 * @handle: transaction to new buffer to
777 * @bh: new buffer.
778 *
779 * Call this if you create a new bh.
780 */
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700781int journal_get_create_access(handle_t *handle, struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782{
783 transaction_t *transaction = handle->h_transaction;
784 journal_t *journal = transaction->t_journal;
785 struct journal_head *jh = journal_add_journal_head(bh);
786 int err;
787
788 jbd_debug(5, "journal_head %p\n", jh);
789 err = -EROFS;
790 if (is_handle_aborted(handle))
791 goto out;
792 err = 0;
793
794 JBUFFER_TRACE(jh, "entry");
795 /*
796 * The buffer may already belong to this transaction due to pre-zeroing
797 * in the filesystem's new_block code. It may also be on the previous,
798 * committing transaction's lists, but it HAS to be in Forget state in
799 * that case: the transaction must have deleted the buffer for it to be
800 * reused here.
801 */
802 jbd_lock_bh_state(bh);
803 spin_lock(&journal->j_list_lock);
804 J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
805 jh->b_transaction == NULL ||
806 (jh->b_transaction == journal->j_committing_transaction &&
807 jh->b_jlist == BJ_Forget)));
808
809 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
810 J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
811
812 if (jh->b_transaction == NULL) {
813 jh->b_transaction = transaction;
814 JBUFFER_TRACE(jh, "file as BJ_Reserved");
815 __journal_file_buffer(jh, transaction, BJ_Reserved);
816 } else if (jh->b_transaction == journal->j_committing_transaction) {
817 JBUFFER_TRACE(jh, "set next transaction");
818 jh->b_next_transaction = transaction;
819 }
820 spin_unlock(&journal->j_list_lock);
821 jbd_unlock_bh_state(bh);
822
823 /*
824 * akpm: I added this. ext3_alloc_branch can pick up new indirect
825 * blocks which contain freed but then revoked metadata. We need
826 * to cancel the revoke in case we end up freeing it yet again
827 * and the reallocating as data - this would cause a second revoke,
828 * which hits an assertion error.
829 */
830 JBUFFER_TRACE(jh, "cancelling revoke");
831 journal_cancel_revoke(handle, jh);
832 journal_put_journal_head(jh);
833out:
834 return err;
835}
836
837/**
838 * int journal_get_undo_access() - Notify intent to modify metadata with
839 * non-rewindable consequences
840 * @handle: transaction
841 * @bh: buffer to undo
842 * @credits: store the number of taken credits here (if not NULL)
843 *
844 * Sometimes there is a need to distinguish between metadata which has
845 * been committed to disk and that which has not. The ext3fs code uses
846 * this for freeing and allocating space, we have to make sure that we
847 * do not reuse freed space until the deallocation has been committed,
848 * since if we overwrote that space we would make the delete
849 * un-rewindable in case of a crash.
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700850 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851 * To deal with that, journal_get_undo_access requests write access to a
852 * buffer for parts of non-rewindable operations such as delete
853 * operations on the bitmaps. The journaling code must keep a copy of
854 * the buffer's contents prior to the undo_access call until such time
855 * as we know that the buffer has definitely been committed to disk.
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700856 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857 * We never need to know which transaction the committed data is part
858 * of, buffers touched here are guaranteed to be dirtied later and so
859 * will be committed to a new transaction in due course, at which point
860 * we can discard the old committed data pointer.
861 *
862 * Returns error number or 0 on success.
863 */
864int journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
865{
866 int err;
867 struct journal_head *jh = journal_add_journal_head(bh);
868 char *committed_data = NULL;
869
870 JBUFFER_TRACE(jh, "entry");
871
872 /*
873 * Do this first --- it can drop the journal lock, so we want to
874 * make sure that obtaining the committed_data is done
875 * atomically wrt. completion of any outstanding commits.
876 */
877 err = do_get_write_access(handle, jh, 1);
878 if (err)
879 goto out;
880
881repeat:
882 if (!jh->b_committed_data) {
Badari Pulavartyea817392006-08-27 01:23:52 -0700883 committed_data = jbd_slab_alloc(jh2bh(jh)->b_size, GFP_NOFS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700884 if (!committed_data) {
885 printk(KERN_EMERG "%s: No memory for committed data\n",
886 __FUNCTION__);
887 err = -ENOMEM;
888 goto out;
889 }
890 }
891
892 jbd_lock_bh_state(bh);
893 if (!jh->b_committed_data) {
894 /* Copy out the current buffer contents into the
895 * preserved, committed copy. */
896 JBUFFER_TRACE(jh, "generate b_committed data");
897 if (!committed_data) {
898 jbd_unlock_bh_state(bh);
899 goto repeat;
900 }
901
902 jh->b_committed_data = committed_data;
903 committed_data = NULL;
904 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
905 }
906 jbd_unlock_bh_state(bh);
907out:
908 journal_put_journal_head(jh);
Andrew Morton304c4c82006-06-23 02:05:31 -0700909 if (unlikely(committed_data))
Badari Pulavartyea817392006-08-27 01:23:52 -0700910 jbd_slab_free(committed_data, bh->b_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911 return err;
912}
913
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700914/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915 * int journal_dirty_data() - mark a buffer as containing dirty data which
916 * needs to be flushed before we can commit the
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700917 * current transaction.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700918 * @handle: transaction
919 * @bh: bufferhead to mark
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700920 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921 * The buffer is placed on the transaction's data list and is marked as
922 * belonging to the transaction.
923 *
924 * Returns error number or 0 on success.
925 *
926 * journal_dirty_data() can be called via page_launder->ext3_writepage
927 * by kswapd.
928 */
929int journal_dirty_data(handle_t *handle, struct buffer_head *bh)
930{
931 journal_t *journal = handle->h_transaction->t_journal;
932 int need_brelse = 0;
933 struct journal_head *jh;
934
935 if (is_handle_aborted(handle))
936 return 0;
937
938 jh = journal_add_journal_head(bh);
939 JBUFFER_TRACE(jh, "entry");
940
941 /*
942 * The buffer could *already* be dirty. Writeout can start
943 * at any time.
944 */
945 jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
946
947 /*
948 * What if the buffer is already part of a running transaction?
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700949 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950 * There are two cases:
951 * 1) It is part of the current running transaction. Refile it,
952 * just in case we have allocated it as metadata, deallocated
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700953 * it, then reallocated it as data.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954 * 2) It is part of the previous, still-committing transaction.
955 * If all we want to do is to guarantee that the buffer will be
956 * written to disk before this new transaction commits, then
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700957 * being sure that the *previous* transaction has this same
Linus Torvalds1da177e2005-04-16 15:20:36 -0700958 * property is sufficient for us! Just leave it on its old
959 * transaction.
960 *
961 * In case (2), the buffer must not already exist as metadata
962 * --- that would violate write ordering (a transaction is free
963 * to write its data at any point, even before the previous
964 * committing transaction has committed). The caller must
965 * never, ever allow this to happen: there's nothing we can do
966 * about it in this layer.
967 */
968 jbd_lock_bh_state(bh);
969 spin_lock(&journal->j_list_lock);
970 if (jh->b_transaction) {
971 JBUFFER_TRACE(jh, "has transaction");
972 if (jh->b_transaction != handle->h_transaction) {
973 JBUFFER_TRACE(jh, "belongs to older transaction");
974 J_ASSERT_JH(jh, jh->b_transaction ==
975 journal->j_committing_transaction);
976
977 /* @@@ IS THIS TRUE ? */
978 /*
979 * Not any more. Scenario: someone does a write()
980 * in data=journal mode. The buffer's transaction has
981 * moved into commit. Then someone does another
982 * write() to the file. We do the frozen data copyout
983 * and set b_next_transaction to point to j_running_t.
984 * And while we're in that state, someone does a
985 * writepage() in an attempt to pageout the same area
986 * of the file via a shared mapping. At present that
987 * calls journal_dirty_data(), and we get right here.
988 * It may be too late to journal the data. Simply
989 * falling through to the next test will suffice: the
990 * data will be dirty and wil be checkpointed. The
991 * ordering comments in the next comment block still
992 * apply.
993 */
994 //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
995
996 /*
997 * If we're journalling data, and this buffer was
998 * subject to a write(), it could be metadata, forget
999 * or shadow against the committing transaction. Now,
1000 * someone has dirtied the same darn page via a mapping
1001 * and it is being writepage()'d.
1002 * We *could* just steal the page from commit, with some
1003 * fancy locking there. Instead, we just skip it -
1004 * don't tie the page's buffers to the new transaction
1005 * at all.
1006 * Implication: if we crash before the writepage() data
1007 * is written into the filesystem, recovery will replay
1008 * the write() data.
1009 */
1010 if (jh->b_jlist != BJ_None &&
1011 jh->b_jlist != BJ_SyncData &&
1012 jh->b_jlist != BJ_Locked) {
1013 JBUFFER_TRACE(jh, "Not stealing");
1014 goto no_journal;
1015 }
1016
1017 /*
1018 * This buffer may be undergoing writeout in commit. We
1019 * can't return from here and let the caller dirty it
1020 * again because that can cause the write-out loop in
1021 * commit to never terminate.
1022 */
1023 if (buffer_dirty(bh)) {
1024 get_bh(bh);
1025 spin_unlock(&journal->j_list_lock);
1026 jbd_unlock_bh_state(bh);
1027 need_brelse = 1;
1028 sync_dirty_buffer(bh);
1029 jbd_lock_bh_state(bh);
1030 spin_lock(&journal->j_list_lock);
1031 /* The buffer may become locked again at any
1032 time if it is redirtied */
1033 }
1034
1035 /* journal_clean_data_list() may have got there first */
1036 if (jh->b_transaction != NULL) {
1037 JBUFFER_TRACE(jh, "unfile from commit");
1038 __journal_temp_unlink_buffer(jh);
1039 /* It still points to the committing
1040 * transaction; move it to this one so
1041 * that the refile assert checks are
1042 * happy. */
1043 jh->b_transaction = handle->h_transaction;
1044 }
1045 /* The buffer will be refiled below */
1046
1047 }
1048 /*
1049 * Special case --- the buffer might actually have been
1050 * allocated and then immediately deallocated in the previous,
1051 * committing transaction, so might still be left on that
1052 * transaction's metadata lists.
1053 */
1054 if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
1055 JBUFFER_TRACE(jh, "not on correct data list: unfile");
1056 J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
1057 __journal_temp_unlink_buffer(jh);
1058 jh->b_transaction = handle->h_transaction;
1059 JBUFFER_TRACE(jh, "file as data");
1060 __journal_file_buffer(jh, handle->h_transaction,
1061 BJ_SyncData);
1062 }
1063 } else {
1064 JBUFFER_TRACE(jh, "not on a transaction");
1065 __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
1066 }
1067no_journal:
1068 spin_unlock(&journal->j_list_lock);
1069 jbd_unlock_bh_state(bh);
1070 if (need_brelse) {
1071 BUFFER_TRACE(bh, "brelse");
1072 __brelse(bh);
1073 }
1074 JBUFFER_TRACE(jh, "exit");
1075 journal_put_journal_head(jh);
1076 return 0;
1077}
1078
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001079/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001080 * int journal_dirty_metadata() - mark a buffer as containing dirty metadata
1081 * @handle: transaction to add buffer to.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001082 * @bh: buffer to mark
1083 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001084 * mark dirty metadata which needs to be journaled as part of the current
1085 * transaction.
1086 *
1087 * The buffer is placed on the transaction's metadata list and is marked
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001088 * as belonging to the transaction.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001089 *
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001090 * Returns error number or 0 on success.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001091 *
1092 * Special care needs to be taken if the buffer already belongs to the
1093 * current committing transaction (in which case we should have frozen
1094 * data present for that commit). In that case, we don't relink the
1095 * buffer: that only gets done when the old transaction finally
1096 * completes its commit.
1097 */
1098int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1099{
1100 transaction_t *transaction = handle->h_transaction;
1101 journal_t *journal = transaction->t_journal;
1102 struct journal_head *jh = bh2jh(bh);
1103
1104 jbd_debug(5, "journal_head %p\n", jh);
1105 JBUFFER_TRACE(jh, "entry");
1106 if (is_handle_aborted(handle))
1107 goto out;
1108
1109 jbd_lock_bh_state(bh);
1110
1111 if (jh->b_modified == 0) {
1112 /*
1113 * This buffer's got modified and becoming part
1114 * of the transaction. This needs to be done
1115 * once a transaction -bzzz
1116 */
1117 jh->b_modified = 1;
1118 J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
1119 handle->h_buffer_credits--;
1120 }
1121
1122 /*
1123 * fastpath, to avoid expensive locking. If this buffer is already
1124 * on the running transaction's metadata list there is nothing to do.
1125 * Nobody can take it off again because there is a handle open.
1126 * I _think_ we're OK here with SMP barriers - a mistaken decision will
1127 * result in this test being false, so we go in and take the locks.
1128 */
1129 if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1130 JBUFFER_TRACE(jh, "fastpath");
1131 J_ASSERT_JH(jh, jh->b_transaction ==
1132 journal->j_running_transaction);
1133 goto out_unlock_bh;
1134 }
1135
1136 set_buffer_jbddirty(bh);
1137
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001138 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001139 * Metadata already on the current transaction list doesn't
1140 * need to be filed. Metadata on another transaction's list must
1141 * be committing, and will be refiled once the commit completes:
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001142 * leave it alone for now.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001143 */
1144 if (jh->b_transaction != transaction) {
1145 JBUFFER_TRACE(jh, "already on other transaction");
1146 J_ASSERT_JH(jh, jh->b_transaction ==
1147 journal->j_committing_transaction);
1148 J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
1149 /* And this case is illegal: we can't reuse another
1150 * transaction's data buffer, ever. */
1151 goto out_unlock_bh;
1152 }
1153
1154 /* That test should have eliminated the following case: */
1155 J_ASSERT_JH(jh, jh->b_frozen_data == 0);
1156
1157 JBUFFER_TRACE(jh, "file as BJ_Metadata");
1158 spin_lock(&journal->j_list_lock);
1159 __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1160 spin_unlock(&journal->j_list_lock);
1161out_unlock_bh:
1162 jbd_unlock_bh_state(bh);
1163out:
1164 JBUFFER_TRACE(jh, "exit");
1165 return 0;
1166}
1167
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001168/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001169 * journal_release_buffer: undo a get_write_access without any buffer
1170 * updates, if the update decided in the end that it didn't need access.
1171 *
1172 */
1173void
1174journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1175{
1176 BUFFER_TRACE(bh, "entry");
1177}
1178
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001179/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180 * void journal_forget() - bforget() for potentially-journaled buffers.
1181 * @handle: transaction handle
1182 * @bh: bh to 'forget'
1183 *
1184 * We can only do the bforget if there are no commits pending against the
1185 * buffer. If the buffer is dirty in the current running transaction we
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001186 * can safely unlink it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001187 *
1188 * bh may not be a journalled buffer at all - it may be a non-JBD
1189 * buffer which came off the hashtable. Check for this.
1190 *
1191 * Decrements bh->b_count by one.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001192 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193 * Allow this call even if the handle has aborted --- it may be part of
1194 * the caller's cleanup after an abort.
1195 */
1196int journal_forget (handle_t *handle, struct buffer_head *bh)
1197{
1198 transaction_t *transaction = handle->h_transaction;
1199 journal_t *journal = transaction->t_journal;
1200 struct journal_head *jh;
1201 int drop_reserve = 0;
1202 int err = 0;
1203
1204 BUFFER_TRACE(bh, "entry");
1205
1206 jbd_lock_bh_state(bh);
1207 spin_lock(&journal->j_list_lock);
1208
1209 if (!buffer_jbd(bh))
1210 goto not_jbd;
1211 jh = bh2jh(bh);
1212
1213 /* Critical error: attempting to delete a bitmap buffer, maybe?
1214 * Don't do any jbd operations, and return an error. */
1215 if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1216 "inconsistent data on disk")) {
1217 err = -EIO;
1218 goto not_jbd;
1219 }
1220
1221 /*
1222 * The buffer's going from the transaction, we must drop
1223 * all references -bzzz
1224 */
1225 jh->b_modified = 0;
1226
1227 if (jh->b_transaction == handle->h_transaction) {
1228 J_ASSERT_JH(jh, !jh->b_frozen_data);
1229
1230 /* If we are forgetting a buffer which is already part
1231 * of this transaction, then we can just drop it from
1232 * the transaction immediately. */
1233 clear_buffer_dirty(bh);
1234 clear_buffer_jbddirty(bh);
1235
1236 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1237
1238 drop_reserve = 1;
1239
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001240 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001241 * We are no longer going to journal this buffer.
1242 * However, the commit of this transaction is still
1243 * important to the buffer: the delete that we are now
1244 * processing might obsolete an old log entry, so by
1245 * committing, we can satisfy the buffer's checkpoint.
1246 *
1247 * So, if we have a checkpoint on the buffer, we should
1248 * now refile the buffer on our BJ_Forget list so that
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001249 * we know to remove the checkpoint after we commit.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001250 */
1251
1252 if (jh->b_cp_transaction) {
1253 __journal_temp_unlink_buffer(jh);
1254 __journal_file_buffer(jh, transaction, BJ_Forget);
1255 } else {
1256 __journal_unfile_buffer(jh);
1257 journal_remove_journal_head(bh);
1258 __brelse(bh);
1259 if (!buffer_jbd(bh)) {
1260 spin_unlock(&journal->j_list_lock);
1261 jbd_unlock_bh_state(bh);
1262 __bforget(bh);
1263 goto drop;
1264 }
1265 }
1266 } else if (jh->b_transaction) {
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001267 J_ASSERT_JH(jh, (jh->b_transaction ==
Linus Torvalds1da177e2005-04-16 15:20:36 -07001268 journal->j_committing_transaction));
1269 /* However, if the buffer is still owned by a prior
1270 * (committing) transaction, we can't drop it yet... */
1271 JBUFFER_TRACE(jh, "belongs to older transaction");
1272 /* ... but we CAN drop it from the new transaction if we
1273 * have also modified it since the original commit. */
1274
1275 if (jh->b_next_transaction) {
1276 J_ASSERT(jh->b_next_transaction == transaction);
1277 jh->b_next_transaction = NULL;
1278 drop_reserve = 1;
1279 }
1280 }
1281
1282not_jbd:
1283 spin_unlock(&journal->j_list_lock);
1284 jbd_unlock_bh_state(bh);
1285 __brelse(bh);
1286drop:
1287 if (drop_reserve) {
1288 /* no need to reserve log space for this block -bzzz */
1289 handle->h_buffer_credits++;
1290 }
1291 return err;
1292}
1293
1294/**
1295 * int journal_stop() - complete a transaction
1296 * @handle: tranaction to complete.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001297 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298 * All done for a particular handle.
1299 *
1300 * There is not much action needed here. We just return any remaining
1301 * buffer credits to the transaction and remove the handle. The only
1302 * complication is that we need to start a commit operation if the
1303 * filesystem is marked for synchronous update.
1304 *
1305 * journal_stop itself will not usually return an error, but it may
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001306 * do so in unusual circumstances. In particular, expect it to
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307 * return -EIO if a journal_abort has been executed since the
1308 * transaction began.
1309 */
1310int journal_stop(handle_t *handle)
1311{
1312 transaction_t *transaction = handle->h_transaction;
1313 journal_t *journal = transaction->t_journal;
1314 int old_handle_count, err;
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001315 pid_t pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001316
1317 J_ASSERT(transaction->t_updates > 0);
1318 J_ASSERT(journal_current_handle() == handle);
1319
1320 if (is_handle_aborted(handle))
1321 err = -EIO;
1322 else
1323 err = 0;
1324
1325 if (--handle->h_ref > 0) {
1326 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1327 handle->h_ref);
1328 return err;
1329 }
1330
1331 jbd_debug(4, "Handle %p going down\n", handle);
1332
1333 /*
1334 * Implement synchronous transaction batching. If the handle
1335 * was synchronous, don't force a commit immediately. Let's
1336 * yield and let another thread piggyback onto this transaction.
1337 * Keep doing that while new threads continue to arrive.
1338 * It doesn't cost much - we're about to run a commit and sleep
1339 * on IO anyway. Speeds up many-threaded, many-dir operations
1340 * by 30x or more...
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001341 *
1342 * But don't do this if this process was the most recent one to
1343 * perform a synchronous write. We do this to detect the case where a
1344 * single process is doing a stream of sync writes. No point in waiting
1345 * for joiners in that case.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346 */
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001347 pid = current->pid;
1348 if (handle->h_sync && journal->j_last_sync_writer != pid) {
1349 journal->j_last_sync_writer = pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001350 do {
1351 old_handle_count = transaction->t_handle_count;
Nishanth Aravamudan041e0e32005-09-10 00:27:23 -07001352 schedule_timeout_uninterruptible(1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353 } while (old_handle_count != transaction->t_handle_count);
1354 }
1355
1356 current->journal_info = NULL;
1357 spin_lock(&journal->j_state_lock);
1358 spin_lock(&transaction->t_handle_lock);
1359 transaction->t_outstanding_credits -= handle->h_buffer_credits;
1360 transaction->t_updates--;
1361 if (!transaction->t_updates) {
1362 wake_up(&journal->j_wait_updates);
1363 if (journal->j_barrier_count)
1364 wake_up(&journal->j_wait_transaction_locked);
1365 }
1366
1367 /*
1368 * If the handle is marked SYNC, we need to set another commit
1369 * going! We also want to force a commit if the current
1370 * transaction is occupying too much of the log, or if the
1371 * transaction is too old now.
1372 */
1373 if (handle->h_sync ||
1374 transaction->t_outstanding_credits >
1375 journal->j_max_transaction_buffers ||
Dave Kleikampe9ad5622006-09-27 01:49:35 -07001376 time_after_eq(jiffies, transaction->t_expires)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377 /* Do this even for aborted journals: an abort still
1378 * completes the commit thread, it just doesn't write
1379 * anything to disk. */
1380 tid_t tid = transaction->t_tid;
1381
1382 spin_unlock(&transaction->t_handle_lock);
1383 jbd_debug(2, "transaction too old, requesting commit for "
1384 "handle %p\n", handle);
1385 /* This is non-blocking */
1386 __log_start_commit(journal, transaction->t_tid);
1387 spin_unlock(&journal->j_state_lock);
1388
1389 /*
1390 * Special case: JFS_SYNC synchronous updates require us
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001391 * to wait for the commit to complete.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001392 */
1393 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1394 err = log_wait_commit(journal, tid);
1395 } else {
1396 spin_unlock(&transaction->t_handle_lock);
1397 spin_unlock(&journal->j_state_lock);
1398 }
1399
1400 jbd_free_handle(handle);
1401 return err;
1402}
1403
1404/**int journal_force_commit() - force any uncommitted transactions
1405 * @journal: journal to force
1406 *
1407 * For synchronous operations: force any uncommitted transactions
1408 * to disk. May seem kludgy, but it reuses all the handle batching
1409 * code in a very simple manner.
1410 */
1411int journal_force_commit(journal_t *journal)
1412{
1413 handle_t *handle;
1414 int ret;
1415
1416 handle = journal_start(journal, 1);
1417 if (IS_ERR(handle)) {
1418 ret = PTR_ERR(handle);
1419 } else {
1420 handle->h_sync = 1;
1421 ret = journal_stop(handle);
1422 }
1423 return ret;
1424}
1425
1426/*
1427 *
1428 * List management code snippets: various functions for manipulating the
1429 * transaction buffer lists.
1430 *
1431 */
1432
1433/*
1434 * Append a buffer to a transaction list, given the transaction's list head
1435 * pointer.
1436 *
1437 * j_list_lock is held.
1438 *
1439 * jbd_lock_bh_state(jh2bh(jh)) is held.
1440 */
1441
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001442static inline void
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443__blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1444{
1445 if (!*list) {
1446 jh->b_tnext = jh->b_tprev = jh;
1447 *list = jh;
1448 } else {
1449 /* Insert at the tail of the list to preserve order */
1450 struct journal_head *first = *list, *last = first->b_tprev;
1451 jh->b_tprev = last;
1452 jh->b_tnext = first;
1453 last->b_tnext = first->b_tprev = jh;
1454 }
1455}
1456
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001457/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 * Remove a buffer from a transaction list, given the transaction's list
1459 * head pointer.
1460 *
1461 * Called with j_list_lock held, and the journal may not be locked.
1462 *
1463 * jbd_lock_bh_state(jh2bh(jh)) is held.
1464 */
1465
1466static inline void
1467__blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1468{
1469 if (*list == jh) {
1470 *list = jh->b_tnext;
1471 if (*list == jh)
1472 *list = NULL;
1473 }
1474 jh->b_tprev->b_tnext = jh->b_tnext;
1475 jh->b_tnext->b_tprev = jh->b_tprev;
1476}
1477
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001478/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001479 * Remove a buffer from the appropriate transaction list.
1480 *
1481 * Note that this function can *change* the value of
1482 * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
1483 * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller
1484 * is holding onto a copy of one of thee pointers, it could go bad.
1485 * Generally the caller needs to re-read the pointer from the transaction_t.
1486 *
1487 * Called under j_list_lock. The journal may not be locked.
1488 */
1489void __journal_temp_unlink_buffer(struct journal_head *jh)
1490{
1491 struct journal_head **list = NULL;
1492 transaction_t *transaction;
1493 struct buffer_head *bh = jh2bh(jh);
1494
1495 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1496 transaction = jh->b_transaction;
1497 if (transaction)
1498 assert_spin_locked(&transaction->t_journal->j_list_lock);
1499
1500 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1501 if (jh->b_jlist != BJ_None)
1502 J_ASSERT_JH(jh, transaction != 0);
1503
1504 switch (jh->b_jlist) {
1505 case BJ_None:
1506 return;
1507 case BJ_SyncData:
1508 list = &transaction->t_sync_datalist;
1509 break;
1510 case BJ_Metadata:
1511 transaction->t_nr_buffers--;
1512 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1513 list = &transaction->t_buffers;
1514 break;
1515 case BJ_Forget:
1516 list = &transaction->t_forget;
1517 break;
1518 case BJ_IO:
1519 list = &transaction->t_iobuf_list;
1520 break;
1521 case BJ_Shadow:
1522 list = &transaction->t_shadow_list;
1523 break;
1524 case BJ_LogCtl:
1525 list = &transaction->t_log_list;
1526 break;
1527 case BJ_Reserved:
1528 list = &transaction->t_reserved_list;
1529 break;
1530 case BJ_Locked:
1531 list = &transaction->t_locked_list;
1532 break;
1533 }
1534
1535 __blist_del_buffer(list, jh);
1536 jh->b_jlist = BJ_None;
1537 if (test_clear_buffer_jbddirty(bh))
1538 mark_buffer_dirty(bh); /* Expose it to the VM */
1539}
1540
1541void __journal_unfile_buffer(struct journal_head *jh)
1542{
1543 __journal_temp_unlink_buffer(jh);
1544 jh->b_transaction = NULL;
1545}
1546
1547void journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1548{
1549 jbd_lock_bh_state(jh2bh(jh));
1550 spin_lock(&journal->j_list_lock);
1551 __journal_unfile_buffer(jh);
1552 spin_unlock(&journal->j_list_lock);
1553 jbd_unlock_bh_state(jh2bh(jh));
1554}
1555
1556/*
1557 * Called from journal_try_to_free_buffers().
1558 *
1559 * Called under jbd_lock_bh_state(bh)
1560 */
1561static void
1562__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1563{
1564 struct journal_head *jh;
1565
1566 jh = bh2jh(bh);
1567
1568 if (buffer_locked(bh) || buffer_dirty(bh))
1569 goto out;
1570
1571 if (jh->b_next_transaction != 0)
1572 goto out;
1573
1574 spin_lock(&journal->j_list_lock);
1575 if (jh->b_transaction != 0 && jh->b_cp_transaction == 0) {
1576 if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
1577 /* A written-back ordered data buffer */
1578 JBUFFER_TRACE(jh, "release data");
1579 __journal_unfile_buffer(jh);
1580 journal_remove_journal_head(bh);
1581 __brelse(bh);
1582 }
1583 } else if (jh->b_cp_transaction != 0 && jh->b_transaction == 0) {
1584 /* written-back checkpointed metadata buffer */
1585 if (jh->b_jlist == BJ_None) {
1586 JBUFFER_TRACE(jh, "remove from checkpoint list");
1587 __journal_remove_checkpoint(jh);
1588 journal_remove_journal_head(bh);
1589 __brelse(bh);
1590 }
1591 }
1592 spin_unlock(&journal->j_list_lock);
1593out:
1594 return;
1595}
1596
1597
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001598/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599 * int journal_try_to_free_buffers() - try to free page buffers.
1600 * @journal: journal for operation
1601 * @page: to try and free
1602 * @unused_gfp_mask: unused
1603 *
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001604 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001605 * For all the buffers on this page,
1606 * if they are fully written out ordered data, move them onto BUF_CLEAN
1607 * so try_to_free_buffers() can reap them.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001608 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609 * This function returns non-zero if we wish try_to_free_buffers()
1610 * to be called. We do this if the page is releasable by try_to_free_buffers().
1611 * We also do it if the page has locked or dirty buffers and the caller wants
1612 * us to perform sync or async writeout.
1613 *
1614 * This complicates JBD locking somewhat. We aren't protected by the
1615 * BKL here. We wish to remove the buffer from its committing or
1616 * running transaction's ->t_datalist via __journal_unfile_buffer.
1617 *
1618 * This may *change* the value of transaction_t->t_datalist, so anyone
1619 * who looks at t_datalist needs to lock against this function.
1620 *
1621 * Even worse, someone may be doing a journal_dirty_data on this
1622 * buffer. So we need to lock against that. journal_dirty_data()
1623 * will come out of the lock with the buffer dirty, which makes it
1624 * ineligible for release here.
1625 *
1626 * Who else is affected by this? hmm... Really the only contender
1627 * is do_get_write_access() - it could be looking at the buffer while
1628 * journal_try_to_free_buffer() is changing its state. But that
1629 * cannot happen because we never reallocate freed data as metadata
1630 * while the data is part of a transaction. Yes?
1631 */
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001632int journal_try_to_free_buffers(journal_t *journal,
Al Viro27496a82005-10-21 03:20:48 -04001633 struct page *page, gfp_t unused_gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001634{
1635 struct buffer_head *head;
1636 struct buffer_head *bh;
1637 int ret = 0;
1638
1639 J_ASSERT(PageLocked(page));
1640
1641 head = page_buffers(page);
1642 bh = head;
1643 do {
1644 struct journal_head *jh;
1645
1646 /*
1647 * We take our own ref against the journal_head here to avoid
1648 * having to add tons of locking around each instance of
1649 * journal_remove_journal_head() and journal_put_journal_head().
1650 */
1651 jh = journal_grab_journal_head(bh);
1652 if (!jh)
1653 continue;
1654
1655 jbd_lock_bh_state(bh);
1656 __journal_try_to_free_buffer(journal, bh);
1657 journal_put_journal_head(jh);
1658 jbd_unlock_bh_state(bh);
1659 if (buffer_jbd(bh))
1660 goto busy;
1661 } while ((bh = bh->b_this_page) != head);
1662 ret = try_to_free_buffers(page);
1663busy:
1664 return ret;
1665}
1666
1667/*
1668 * This buffer is no longer needed. If it is on an older transaction's
1669 * checkpoint list we need to record it on this transaction's forget list
1670 * to pin this buffer (and hence its checkpointing transaction) down until
1671 * this transaction commits. If the buffer isn't on a checkpoint list, we
1672 * release it.
1673 * Returns non-zero if JBD no longer has an interest in the buffer.
1674 *
1675 * Called under j_list_lock.
1676 *
1677 * Called under jbd_lock_bh_state(bh).
1678 */
1679static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1680{
1681 int may_free = 1;
1682 struct buffer_head *bh = jh2bh(jh);
1683
1684 __journal_unfile_buffer(jh);
1685
1686 if (jh->b_cp_transaction) {
1687 JBUFFER_TRACE(jh, "on running+cp transaction");
1688 __journal_file_buffer(jh, transaction, BJ_Forget);
1689 clear_buffer_jbddirty(bh);
1690 may_free = 0;
1691 } else {
1692 JBUFFER_TRACE(jh, "on running transaction");
1693 journal_remove_journal_head(bh);
1694 __brelse(bh);
1695 }
1696 return may_free;
1697}
1698
1699/*
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001700 * journal_invalidatepage
Linus Torvalds1da177e2005-04-16 15:20:36 -07001701 *
1702 * This code is tricky. It has a number of cases to deal with.
1703 *
1704 * There are two invariants which this code relies on:
1705 *
1706 * i_size must be updated on disk before we start calling invalidatepage on the
1707 * data.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001708 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001709 * This is done in ext3 by defining an ext3_setattr method which
1710 * updates i_size before truncate gets going. By maintaining this
1711 * invariant, we can be sure that it is safe to throw away any buffers
1712 * attached to the current transaction: once the transaction commits,
1713 * we know that the data will not be needed.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001714 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715 * Note however that we can *not* throw away data belonging to the
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001716 * previous, committing transaction!
Linus Torvalds1da177e2005-04-16 15:20:36 -07001717 *
1718 * Any disk blocks which *are* part of the previous, committing
1719 * transaction (and which therefore cannot be discarded immediately) are
1720 * not going to be reused in the new running transaction
1721 *
1722 * The bitmap committed_data images guarantee this: any block which is
1723 * allocated in one transaction and removed in the next will be marked
1724 * as in-use in the committed_data bitmap, so cannot be reused until
1725 * the next transaction to delete the block commits. This means that
1726 * leaving committing buffers dirty is quite safe: the disk blocks
1727 * cannot be reallocated to a different file and so buffer aliasing is
1728 * not possible.
1729 *
1730 *
1731 * The above applies mainly to ordered data mode. In writeback mode we
1732 * don't make guarantees about the order in which data hits disk --- in
1733 * particular we don't guarantee that new dirty data is flushed before
1734 * transaction commit --- so it is always safe just to discard data
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001735 * immediately in that mode. --sct
Linus Torvalds1da177e2005-04-16 15:20:36 -07001736 */
1737
1738/*
1739 * The journal_unmap_buffer helper function returns zero if the buffer
1740 * concerned remains pinned as an anonymous buffer belonging to an older
1741 * transaction.
1742 *
1743 * We're outside-transaction here. Either or both of j_running_transaction
1744 * and j_committing_transaction may be NULL.
1745 */
1746static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1747{
1748 transaction_t *transaction;
1749 struct journal_head *jh;
1750 int may_free = 1;
1751 int ret;
1752
1753 BUFFER_TRACE(bh, "entry");
1754
1755 /*
1756 * It is safe to proceed here without the j_list_lock because the
1757 * buffers cannot be stolen by try_to_free_buffers as long as we are
1758 * holding the page lock. --sct
1759 */
1760
1761 if (!buffer_jbd(bh))
1762 goto zap_buffer_unlocked;
1763
1764 spin_lock(&journal->j_state_lock);
1765 jbd_lock_bh_state(bh);
1766 spin_lock(&journal->j_list_lock);
1767
1768 jh = journal_grab_journal_head(bh);
1769 if (!jh)
1770 goto zap_buffer_no_jh;
1771
1772 transaction = jh->b_transaction;
1773 if (transaction == NULL) {
1774 /* First case: not on any transaction. If it
1775 * has no checkpoint link, then we can zap it:
1776 * it's a writeback-mode buffer so we don't care
1777 * if it hits disk safely. */
1778 if (!jh->b_cp_transaction) {
1779 JBUFFER_TRACE(jh, "not on any transaction: zap");
1780 goto zap_buffer;
1781 }
1782
1783 if (!buffer_dirty(bh)) {
1784 /* bdflush has written it. We can drop it now */
1785 goto zap_buffer;
1786 }
1787
1788 /* OK, it must be in the journal but still not
1789 * written fully to disk: it's metadata or
1790 * journaled data... */
1791
1792 if (journal->j_running_transaction) {
1793 /* ... and once the current transaction has
1794 * committed, the buffer won't be needed any
1795 * longer. */
1796 JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1797 ret = __dispose_buffer(jh,
1798 journal->j_running_transaction);
1799 journal_put_journal_head(jh);
1800 spin_unlock(&journal->j_list_lock);
1801 jbd_unlock_bh_state(bh);
1802 spin_unlock(&journal->j_state_lock);
1803 return ret;
1804 } else {
1805 /* There is no currently-running transaction. So the
1806 * orphan record which we wrote for this file must have
1807 * passed into commit. We must attach this buffer to
1808 * the committing transaction, if it exists. */
1809 if (journal->j_committing_transaction) {
1810 JBUFFER_TRACE(jh, "give to committing trans");
1811 ret = __dispose_buffer(jh,
1812 journal->j_committing_transaction);
1813 journal_put_journal_head(jh);
1814 spin_unlock(&journal->j_list_lock);
1815 jbd_unlock_bh_state(bh);
1816 spin_unlock(&journal->j_state_lock);
1817 return ret;
1818 } else {
1819 /* The orphan record's transaction has
1820 * committed. We can cleanse this buffer */
1821 clear_buffer_jbddirty(bh);
1822 goto zap_buffer;
1823 }
1824 }
1825 } else if (transaction == journal->j_committing_transaction) {
akpm@osdl.orgd13df842005-04-16 15:26:36 -07001826 if (jh->b_jlist == BJ_Locked) {
1827 /*
1828 * The buffer is on the committing transaction's locked
1829 * list. We have the buffer locked, so I/O has
1830 * completed. So we can nail the buffer now.
1831 */
1832 may_free = __dispose_buffer(jh, transaction);
1833 goto zap_buffer;
1834 }
1835 /*
1836 * If it is committing, we simply cannot touch it. We
Linus Torvalds1da177e2005-04-16 15:20:36 -07001837 * can remove it's next_transaction pointer from the
1838 * running transaction if that is set, but nothing
1839 * else. */
1840 JBUFFER_TRACE(jh, "on committing transaction");
1841 set_buffer_freed(bh);
1842 if (jh->b_next_transaction) {
1843 J_ASSERT(jh->b_next_transaction ==
1844 journal->j_running_transaction);
1845 jh->b_next_transaction = NULL;
1846 }
1847 journal_put_journal_head(jh);
1848 spin_unlock(&journal->j_list_lock);
1849 jbd_unlock_bh_state(bh);
1850 spin_unlock(&journal->j_state_lock);
1851 return 0;
1852 } else {
1853 /* Good, the buffer belongs to the running transaction.
1854 * We are writing our own transaction's data, not any
1855 * previous one's, so it is safe to throw it away
1856 * (remember that we expect the filesystem to have set
1857 * i_size already for this truncate so recovery will not
1858 * expose the disk blocks we are discarding here.) */
1859 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
1860 may_free = __dispose_buffer(jh, transaction);
1861 }
1862
1863zap_buffer:
1864 journal_put_journal_head(jh);
1865zap_buffer_no_jh:
1866 spin_unlock(&journal->j_list_lock);
1867 jbd_unlock_bh_state(bh);
1868 spin_unlock(&journal->j_state_lock);
1869zap_buffer_unlocked:
1870 clear_buffer_dirty(bh);
1871 J_ASSERT_BH(bh, !buffer_jbddirty(bh));
1872 clear_buffer_mapped(bh);
1873 clear_buffer_req(bh);
1874 clear_buffer_new(bh);
1875 bh->b_bdev = NULL;
1876 return may_free;
1877}
1878
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001879/**
NeilBrown2ff28e22006-03-26 01:37:18 -08001880 * void journal_invalidatepage()
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001881 * @journal: journal to use for flush...
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882 * @page: page to flush
1883 * @offset: length of page to invalidate.
1884 *
1885 * Reap page buffers containing data after offset in page.
1886 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001887 */
NeilBrown2ff28e22006-03-26 01:37:18 -08001888void journal_invalidatepage(journal_t *journal,
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001889 struct page *page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001890 unsigned long offset)
1891{
1892 struct buffer_head *head, *bh, *next;
1893 unsigned int curr_off = 0;
1894 int may_free = 1;
1895
1896 if (!PageLocked(page))
1897 BUG();
1898 if (!page_has_buffers(page))
NeilBrown2ff28e22006-03-26 01:37:18 -08001899 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001900
1901 /* We will potentially be playing with lists other than just the
1902 * data lists (especially for journaled data mode), so be
1903 * cautious in our locking. */
1904
1905 head = bh = page_buffers(page);
1906 do {
1907 unsigned int next_off = curr_off + bh->b_size;
1908 next = bh->b_this_page;
1909
Linus Torvalds1da177e2005-04-16 15:20:36 -07001910 if (offset <= curr_off) {
Dave Kleikampe9ad5622006-09-27 01:49:35 -07001911 /* This block is wholly outside the truncation point */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001912 lock_buffer(bh);
1913 may_free &= journal_unmap_buffer(journal, bh);
1914 unlock_buffer(bh);
1915 }
1916 curr_off = next_off;
1917 bh = next;
1918
1919 } while (bh != head);
1920
1921 if (!offset) {
NeilBrown2ff28e22006-03-26 01:37:18 -08001922 if (may_free && try_to_free_buffers(page))
1923 J_ASSERT(!page_has_buffers(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001924 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001925}
1926
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001927/*
1928 * File a buffer on the given transaction list.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001929 */
1930void __journal_file_buffer(struct journal_head *jh,
1931 transaction_t *transaction, int jlist)
1932{
1933 struct journal_head **list = NULL;
1934 int was_dirty = 0;
1935 struct buffer_head *bh = jh2bh(jh);
1936
1937 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1938 assert_spin_locked(&transaction->t_journal->j_list_lock);
1939
1940 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1941 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
1942 jh->b_transaction == 0);
1943
1944 if (jh->b_transaction && jh->b_jlist == jlist)
1945 return;
1946
1947 /* The following list of buffer states needs to be consistent
1948 * with __jbd_unexpected_dirty_buffer()'s handling of dirty
1949 * state. */
1950
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001951 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07001952 jlist == BJ_Shadow || jlist == BJ_Forget) {
1953 if (test_clear_buffer_dirty(bh) ||
1954 test_clear_buffer_jbddirty(bh))
1955 was_dirty = 1;
1956 }
1957
1958 if (jh->b_transaction)
1959 __journal_temp_unlink_buffer(jh);
1960 jh->b_transaction = transaction;
1961
1962 switch (jlist) {
1963 case BJ_None:
1964 J_ASSERT_JH(jh, !jh->b_committed_data);
1965 J_ASSERT_JH(jh, !jh->b_frozen_data);
1966 return;
1967 case BJ_SyncData:
1968 list = &transaction->t_sync_datalist;
1969 break;
1970 case BJ_Metadata:
1971 transaction->t_nr_buffers++;
1972 list = &transaction->t_buffers;
1973 break;
1974 case BJ_Forget:
1975 list = &transaction->t_forget;
1976 break;
1977 case BJ_IO:
1978 list = &transaction->t_iobuf_list;
1979 break;
1980 case BJ_Shadow:
1981 list = &transaction->t_shadow_list;
1982 break;
1983 case BJ_LogCtl:
1984 list = &transaction->t_log_list;
1985 break;
1986 case BJ_Reserved:
1987 list = &transaction->t_reserved_list;
1988 break;
1989 case BJ_Locked:
1990 list = &transaction->t_locked_list;
1991 break;
1992 }
1993
1994 __blist_add_buffer(list, jh);
1995 jh->b_jlist = jlist;
1996
1997 if (was_dirty)
1998 set_buffer_jbddirty(bh);
1999}
2000
2001void journal_file_buffer(struct journal_head *jh,
2002 transaction_t *transaction, int jlist)
2003{
2004 jbd_lock_bh_state(jh2bh(jh));
2005 spin_lock(&transaction->t_journal->j_list_lock);
2006 __journal_file_buffer(jh, transaction, jlist);
2007 spin_unlock(&transaction->t_journal->j_list_lock);
2008 jbd_unlock_bh_state(jh2bh(jh));
2009}
2010
Mingming Caoae6ddcc2006-09-27 01:49:27 -07002011/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002012 * Remove a buffer from its current buffer list in preparation for
2013 * dropping it from its current transaction entirely. If the buffer has
2014 * already started to be used by a subsequent transaction, refile the
2015 * buffer on that transaction's metadata list.
2016 *
2017 * Called under journal->j_list_lock
2018 *
2019 * Called under jbd_lock_bh_state(jh2bh(jh))
2020 */
2021void __journal_refile_buffer(struct journal_head *jh)
2022{
2023 int was_dirty;
2024 struct buffer_head *bh = jh2bh(jh);
2025
2026 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2027 if (jh->b_transaction)
2028 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2029
2030 /* If the buffer is now unused, just drop it. */
2031 if (jh->b_next_transaction == NULL) {
2032 __journal_unfile_buffer(jh);
2033 return;
2034 }
2035
2036 /*
2037 * It has been modified by a later transaction: add it to the new
2038 * transaction's metadata list.
2039 */
2040
2041 was_dirty = test_clear_buffer_jbddirty(bh);
2042 __journal_temp_unlink_buffer(jh);
2043 jh->b_transaction = jh->b_next_transaction;
2044 jh->b_next_transaction = NULL;
Jan Kara9ada7342006-06-23 02:05:25 -07002045 __journal_file_buffer(jh, jh->b_transaction,
2046 was_dirty ? BJ_Metadata : BJ_Reserved);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002047 J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2048
2049 if (was_dirty)
2050 set_buffer_jbddirty(bh);
2051}
2052
2053/*
2054 * For the unlocked version of this call, also make sure that any
2055 * hanging journal_head is cleaned up if necessary.
2056 *
2057 * __journal_refile_buffer is usually called as part of a single locked
2058 * operation on a buffer_head, in which the caller is probably going to
2059 * be hooking the journal_head onto other lists. In that case it is up
2060 * to the caller to remove the journal_head if necessary. For the
2061 * unlocked journal_refile_buffer call, the caller isn't going to be
2062 * doing anything else to the buffer so we need to do the cleanup
Mingming Caoae6ddcc2006-09-27 01:49:27 -07002063 * ourselves to avoid a jh leak.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002064 *
2065 * *** The journal_head may be freed by this call! ***
2066 */
2067void journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2068{
2069 struct buffer_head *bh = jh2bh(jh);
2070
2071 jbd_lock_bh_state(bh);
2072 spin_lock(&journal->j_list_lock);
2073
2074 __journal_refile_buffer(jh);
2075 jbd_unlock_bh_state(bh);
2076 journal_remove_journal_head(bh);
2077
2078 spin_unlock(&journal->j_list_lock);
2079 __brelse(bh);
2080}