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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Uwe Kleine-König58862692007-05-09 07:51:49 +02002 * linux/fs/jbd/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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070026#include <linux/mm.h>
27#include <linux/highmem.h>
Josef Bacikf420d4d2009-01-07 18:07:24 -080028#include <linux/hrtimer.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029
Adrian Bunkd394e122006-12-06 20:38:26 -080030static void __journal_temp_unlink_buffer(struct journal_head *jh);
31
Linus Torvalds1da177e2005-04-16 15:20:36 -070032/*
33 * get_transaction: obtain a new transaction_t object.
34 *
35 * Simply allocate and initialise a new transaction. Create it in
36 * RUNNING state and add it to the current journal (which should not
37 * have an existing running transaction: we only make a new transaction
38 * once we have started to commit the old one).
39 *
40 * Preconditions:
41 * The journal MUST be locked. We don't perform atomic mallocs on the
42 * new transaction and we can't block without protecting against other
43 * processes trying to touch the journal while it is in transition.
44 *
45 * Called under j_state_lock
46 */
47
48static transaction_t *
49get_transaction(journal_t *journal, transaction_t *transaction)
50{
51 transaction->t_journal = journal;
52 transaction->t_state = T_RUNNING;
Josef Bacikf420d4d2009-01-07 18:07:24 -080053 transaction->t_start_time = ktime_get();
Linus Torvalds1da177e2005-04-16 15:20:36 -070054 transaction->t_tid = journal->j_transaction_sequence++;
55 transaction->t_expires = jiffies + journal->j_commit_interval;
56 spin_lock_init(&transaction->t_handle_lock);
57
58 /* Set up the commit timer for the new transaction. */
Andreas Dilgerb449fc62009-07-30 20:09:46 +020059 journal->j_commit_timer.expires =
60 round_jiffies_up(transaction->t_expires);
Andrew Mortone3df1892006-03-25 03:06:53 -080061 add_timer(&journal->j_commit_timer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070062
63 J_ASSERT(journal->j_running_transaction == NULL);
64 journal->j_running_transaction = transaction;
65
66 return transaction;
67}
68
69/*
70 * Handle management.
71 *
72 * A handle_t is an object which represents a single atomic update to a
73 * filesystem, and which tracks all of the modifications which form part
74 * of that one update.
75 */
76
77/*
78 * start_this_handle: Given a handle, deal with any locking or stalling
79 * needed to make sure that there is enough journal space for the handle
80 * to begin. Attach the handle to a transaction and set up the
Mingming Caoae6ddcc2006-09-27 01:49:27 -070081 * transaction's buffer credits.
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 */
83
84static int start_this_handle(journal_t *journal, handle_t *handle)
85{
86 transaction_t *transaction;
87 int needed;
88 int nblocks = handle->h_buffer_credits;
89 transaction_t *new_transaction = NULL;
90 int ret = 0;
91
92 if (nblocks > journal->j_max_transaction_buffers) {
93 printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
94 current->comm, nblocks,
95 journal->j_max_transaction_buffers);
96 ret = -ENOSPC;
97 goto out;
98 }
99
100alloc_transaction:
101 if (!journal->j_running_transaction) {
Mingming Cao8c3478a2007-10-18 23:39:20 -0700102 new_transaction = kzalloc(sizeof(*new_transaction),
Mingming Caoa5005da2007-10-16 18:38:25 -0400103 GFP_NOFS|__GFP_NOFAIL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 if (!new_transaction) {
105 ret = -ENOMEM;
106 goto out;
107 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 }
109
110 jbd_debug(3, "New handle %p going live.\n", handle);
111
112repeat:
113
114 /*
115 * We need to hold j_state_lock until t_updates has been incremented,
116 * for proper journal barrier handling
117 */
118 spin_lock(&journal->j_state_lock);
119repeat_locked:
120 if (is_journal_aborted(journal) ||
121 (journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) {
122 spin_unlock(&journal->j_state_lock);
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700123 ret = -EROFS;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 goto out;
125 }
126
127 /* Wait on the journal's transaction barrier if necessary */
128 if (journal->j_barrier_count) {
129 spin_unlock(&journal->j_state_lock);
130 wait_event(journal->j_wait_transaction_locked,
131 journal->j_barrier_count == 0);
132 goto repeat;
133 }
134
135 if (!journal->j_running_transaction) {
136 if (!new_transaction) {
137 spin_unlock(&journal->j_state_lock);
138 goto alloc_transaction;
139 }
140 get_transaction(journal, new_transaction);
141 new_transaction = NULL;
142 }
143
144 transaction = journal->j_running_transaction;
145
146 /*
147 * If the current transaction is locked down for commit, wait for the
148 * lock to be released.
149 */
150 if (transaction->t_state == T_LOCKED) {
151 DEFINE_WAIT(wait);
152
153 prepare_to_wait(&journal->j_wait_transaction_locked,
154 &wait, TASK_UNINTERRUPTIBLE);
155 spin_unlock(&journal->j_state_lock);
156 schedule();
157 finish_wait(&journal->j_wait_transaction_locked, &wait);
158 goto repeat;
159 }
160
161 /*
162 * If there is not enough space left in the log to write all potential
163 * buffers requested by this operation, we need to stall pending a log
164 * checkpoint to free some more log space.
165 */
166 spin_lock(&transaction->t_handle_lock);
167 needed = transaction->t_outstanding_credits + nblocks;
168
169 if (needed > journal->j_max_transaction_buffers) {
170 /*
171 * If the current transaction is already too large, then start
172 * to commit it: we can then go back and attach this handle to
173 * a new transaction.
174 */
175 DEFINE_WAIT(wait);
176
177 jbd_debug(2, "Handle %p starting new commit...\n", handle);
178 spin_unlock(&transaction->t_handle_lock);
179 prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
180 TASK_UNINTERRUPTIBLE);
181 __log_start_commit(journal, transaction->t_tid);
182 spin_unlock(&journal->j_state_lock);
183 schedule();
184 finish_wait(&journal->j_wait_transaction_locked, &wait);
185 goto repeat;
186 }
187
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700188 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 * The commit code assumes that it can get enough log space
190 * without forcing a checkpoint. This is *critical* for
191 * correctness: a checkpoint of a buffer which is also
192 * associated with a committing transaction creates a deadlock,
193 * so commit simply cannot force through checkpoints.
194 *
195 * We must therefore ensure the necessary space in the journal
196 * *before* starting to dirty potentially checkpointed buffers
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700197 * in the new transaction.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198 *
199 * The worst part is, any transaction currently committing can
200 * reduce the free space arbitrarily. Be careful to account for
201 * those buffers when checkpointing.
202 */
203
204 /*
205 * @@@ AKPM: This seems rather over-defensive. We're giving commit
206 * a _lot_ of headroom: 1/4 of the journal plus the size of
207 * the committing transaction. Really, we only need to give it
208 * committing_transaction->t_outstanding_credits plus "enough" for
209 * the log control blocks.
210 * Also, this test is inconsitent with the matching one in
211 * journal_extend().
212 */
213 if (__log_space_left(journal) < jbd_space_needed(journal)) {
214 jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
215 spin_unlock(&transaction->t_handle_lock);
216 __log_wait_for_space(journal);
217 goto repeat_locked;
218 }
219
220 /* OK, account for the buffers that this operation expects to
221 * use and add the handle to the running transaction. */
222
223 handle->h_transaction = transaction;
224 transaction->t_outstanding_credits += nblocks;
225 transaction->t_updates++;
226 transaction->t_handle_count++;
227 jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
228 handle, nblocks, transaction->t_outstanding_credits,
229 __log_space_left(journal));
230 spin_unlock(&transaction->t_handle_lock);
231 spin_unlock(&journal->j_state_lock);
Jan Kara3adae9d2009-08-11 17:27:21 +0200232
233 lock_map_acquire(&handle->h_lockdep_map);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234out:
Andrew Morton304c4c82006-06-23 02:05:31 -0700235 if (unlikely(new_transaction)) /* It's usually NULL */
236 kfree(new_transaction);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 return ret;
238}
239
Peter Zijlstra34a3d1e2007-10-11 22:11:12 +0200240static struct lock_class_key jbd_handle_key;
241
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242/* Allocate a new handle. This should probably be in a slab... */
243static handle_t *new_handle(int nblocks)
244{
245 handle_t *handle = jbd_alloc_handle(GFP_NOFS);
246 if (!handle)
247 return NULL;
248 memset(handle, 0, sizeof(*handle));
249 handle->h_buffer_credits = nblocks;
250 handle->h_ref = 1;
251
Peter Zijlstra34a3d1e2007-10-11 22:11:12 +0200252 lockdep_init_map(&handle->h_lockdep_map, "jbd_handle", &jbd_handle_key, 0);
253
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254 return handle;
255}
256
257/**
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700258 * handle_t *journal_start() - Obtain a new handle.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 * @journal: Journal to start transaction on.
260 * @nblocks: number of block buffer we might modify
261 *
262 * We make sure that the transaction can guarantee at least nblocks of
263 * modified buffers in the log. We block until the log can guarantee
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700264 * that much space.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 *
266 * This function is visible to journal users (like ext3fs), so is not
267 * called with the journal already locked.
268 *
269 * Return a pointer to a newly allocated handle, or NULL on failure
270 */
271handle_t *journal_start(journal_t *journal, int nblocks)
272{
273 handle_t *handle = journal_current_handle();
274 int err;
275
276 if (!journal)
277 return ERR_PTR(-EROFS);
278
279 if (handle) {
280 J_ASSERT(handle->h_transaction->t_journal == journal);
281 handle->h_ref++;
282 return handle;
283 }
284
285 handle = new_handle(nblocks);
286 if (!handle)
287 return ERR_PTR(-ENOMEM);
288
289 current->journal_info = handle;
290
291 err = start_this_handle(journal, handle);
292 if (err < 0) {
293 jbd_free_handle(handle);
294 current->journal_info = NULL;
295 handle = ERR_PTR(err);
Jonas Bonnf63dcda2008-01-17 15:21:13 -0800296 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 }
Jonas Bonnf63dcda2008-01-17 15:21:13 -0800298out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 return handle;
300}
301
302/**
303 * int journal_extend() - extend buffer credits.
304 * @handle: handle to 'extend'
305 * @nblocks: nr blocks to try to extend by.
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700306 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307 * Some transactions, such as large extends and truncates, can be done
308 * atomically all at once or in several stages. The operation requests
309 * a credit for a number of buffer modications in advance, but can
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700310 * extend its credit if it needs more.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311 *
312 * journal_extend tries to give the running handle more buffer credits.
313 * It does not guarantee that allocation - this is a best-effort only.
314 * The calling process MUST be able to deal cleanly with a failure to
315 * extend here.
316 *
317 * Return 0 on success, non-zero on failure.
318 *
319 * return code < 0 implies an error
320 * return code > 0 implies normal transaction-full status.
321 */
322int journal_extend(handle_t *handle, int nblocks)
323{
324 transaction_t *transaction = handle->h_transaction;
325 journal_t *journal = transaction->t_journal;
326 int result;
327 int wanted;
328
329 result = -EIO;
330 if (is_handle_aborted(handle))
331 goto out;
332
333 result = 1;
334
335 spin_lock(&journal->j_state_lock);
336
337 /* Don't extend a locked-down transaction! */
338 if (handle->h_transaction->t_state != T_RUNNING) {
339 jbd_debug(3, "denied handle %p %d blocks: "
340 "transaction not running\n", handle, nblocks);
341 goto error_out;
342 }
343
344 spin_lock(&transaction->t_handle_lock);
345 wanted = transaction->t_outstanding_credits + nblocks;
346
347 if (wanted > journal->j_max_transaction_buffers) {
348 jbd_debug(3, "denied handle %p %d blocks: "
349 "transaction too large\n", handle, nblocks);
350 goto unlock;
351 }
352
353 if (wanted > __log_space_left(journal)) {
354 jbd_debug(3, "denied handle %p %d blocks: "
355 "insufficient log space\n", handle, nblocks);
356 goto unlock;
357 }
358
359 handle->h_buffer_credits += nblocks;
360 transaction->t_outstanding_credits += nblocks;
361 result = 0;
362
363 jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
364unlock:
365 spin_unlock(&transaction->t_handle_lock);
366error_out:
367 spin_unlock(&journal->j_state_lock);
368out:
369 return result;
370}
371
372
373/**
Randy Dunlap78a4a502008-02-29 22:02:31 -0800374 * int journal_restart() - restart a handle.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 * @handle: handle to restart
376 * @nblocks: nr credits requested
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700377 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 * Restart a handle for a multi-transaction filesystem
379 * operation.
380 *
381 * If the journal_extend() call above fails to grant new buffer credits
382 * to a running handle, a call to journal_restart will commit the
383 * handle's transaction so far and reattach the handle to a new
384 * transaction capabable of guaranteeing the requested number of
385 * credits.
386 */
387
388int journal_restart(handle_t *handle, int nblocks)
389{
390 transaction_t *transaction = handle->h_transaction;
391 journal_t *journal = transaction->t_journal;
392 int ret;
393
394 /* If we've had an abort of any type, don't even think about
395 * actually doing the restart! */
396 if (is_handle_aborted(handle))
397 return 0;
398
399 /*
400 * First unlink the handle from its current transaction, and start the
401 * commit on that.
402 */
403 J_ASSERT(transaction->t_updates > 0);
404 J_ASSERT(journal_current_handle() == handle);
405
406 spin_lock(&journal->j_state_lock);
407 spin_lock(&transaction->t_handle_lock);
408 transaction->t_outstanding_credits -= handle->h_buffer_credits;
409 transaction->t_updates--;
410
411 if (!transaction->t_updates)
412 wake_up(&journal->j_wait_updates);
413 spin_unlock(&transaction->t_handle_lock);
414
415 jbd_debug(2, "restarting handle %p\n", handle);
416 __log_start_commit(journal, transaction->t_tid);
417 spin_unlock(&journal->j_state_lock);
418
Jan Kara3adae9d2009-08-11 17:27:21 +0200419 lock_map_release(&handle->h_lockdep_map);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 handle->h_buffer_credits = nblocks;
421 ret = start_this_handle(journal, handle);
422 return ret;
423}
424
425
426/**
427 * void journal_lock_updates () - establish a transaction barrier.
428 * @journal: Journal to establish a barrier on.
429 *
430 * This locks out any further updates from being started, and blocks
431 * until all existing updates have completed, returning only once the
432 * journal is in a quiescent state with no updates running.
433 *
434 * The journal lock should not be held on entry.
435 */
436void journal_lock_updates(journal_t *journal)
437{
438 DEFINE_WAIT(wait);
439
440 spin_lock(&journal->j_state_lock);
441 ++journal->j_barrier_count;
442
443 /* Wait until there are no running updates */
444 while (1) {
445 transaction_t *transaction = journal->j_running_transaction;
446
447 if (!transaction)
448 break;
449
450 spin_lock(&transaction->t_handle_lock);
451 if (!transaction->t_updates) {
452 spin_unlock(&transaction->t_handle_lock);
453 break;
454 }
455 prepare_to_wait(&journal->j_wait_updates, &wait,
456 TASK_UNINTERRUPTIBLE);
457 spin_unlock(&transaction->t_handle_lock);
458 spin_unlock(&journal->j_state_lock);
459 schedule();
460 finish_wait(&journal->j_wait_updates, &wait);
461 spin_lock(&journal->j_state_lock);
462 }
463 spin_unlock(&journal->j_state_lock);
464
465 /*
466 * We have now established a barrier against other normal updates, but
467 * we also need to barrier against other journal_lock_updates() calls
468 * to make sure that we serialise special journal-locked operations
469 * too.
470 */
Arjan van de Ven2c68ee72006-03-23 03:00:35 -0800471 mutex_lock(&journal->j_barrier);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472}
473
474/**
475 * void journal_unlock_updates (journal_t* journal) - release barrier
476 * @journal: Journal to release the barrier on.
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700477 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478 * Release a transaction barrier obtained with journal_lock_updates().
479 *
480 * Should be called without the journal lock held.
481 */
482void journal_unlock_updates (journal_t *journal)
483{
484 J_ASSERT(journal->j_barrier_count != 0);
485
Arjan van de Ven2c68ee72006-03-23 03:00:35 -0800486 mutex_unlock(&journal->j_barrier);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 spin_lock(&journal->j_state_lock);
488 --journal->j_barrier_count;
489 spin_unlock(&journal->j_state_lock);
490 wake_up(&journal->j_wait_transaction_locked);
491}
492
Jan Kara1e9fd532009-06-24 17:31:40 +0200493static void warn_dirty_buffer(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494{
Jan Kara1e9fd532009-06-24 17:31:40 +0200495 char b[BDEVNAME_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496
Jan Kara1e9fd532009-06-24 17:31:40 +0200497 printk(KERN_WARNING
498 "JBD: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). "
499 "There's a risk of filesystem corruption in case of system "
500 "crash.\n",
501 bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502}
503
504/*
505 * If the buffer is already part of the current transaction, then there
506 * is nothing we need to do. If it is already part of a prior
507 * transaction which we are still committing to disk, then we need to
508 * make sure that we do not overwrite the old copy: we do copy-out to
509 * preserve the copy going to disk. We also account the buffer against
510 * the handle's metadata buffer credits (unless the buffer is already
511 * part of the transaction, that is).
512 *
513 */
514static int
515do_get_write_access(handle_t *handle, struct journal_head *jh,
516 int force_copy)
517{
518 struct buffer_head *bh;
519 transaction_t *transaction;
520 journal_t *journal;
521 int error;
522 char *frozen_buffer = NULL;
523 int need_copy = 0;
524
525 if (is_handle_aborted(handle))
526 return -EROFS;
527
528 transaction = handle->h_transaction;
529 journal = transaction->t_journal;
530
531 jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy);
532
533 JBUFFER_TRACE(jh, "entry");
534repeat:
535 bh = jh2bh(jh);
536
537 /* @@@ Need to check for errors here at some point. */
538
539 lock_buffer(bh);
540 jbd_lock_bh_state(bh);
541
542 /* We now hold the buffer lock so it is safe to query the buffer
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700543 * state. Is the buffer dirty?
544 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545 * If so, there are two possibilities. The buffer may be
546 * non-journaled, and undergoing a quite legitimate writeback.
547 * Otherwise, it is journaled, and we don't expect dirty buffers
548 * in that state (the buffers should be marked JBD_Dirty
549 * instead.) So either the IO is being done under our own
550 * control and this is a bug, or it's a third party IO such as
551 * dump(8) (which may leave the buffer scheduled for read ---
552 * ie. locked but not dirty) or tune2fs (which may actually have
553 * the buffer dirtied, ugh.) */
554
555 if (buffer_dirty(bh)) {
556 /*
557 * First question: is this buffer already part of the current
558 * transaction or the existing committing transaction?
559 */
560 if (jh->b_transaction) {
561 J_ASSERT_JH(jh,
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700562 jh->b_transaction == transaction ||
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563 jh->b_transaction ==
564 journal->j_committing_transaction);
565 if (jh->b_next_transaction)
566 J_ASSERT_JH(jh, jh->b_next_transaction ==
567 transaction);
Jan Kara1e9fd532009-06-24 17:31:40 +0200568 warn_dirty_buffer(bh);
Jan Kara4407c2b2005-09-06 15:19:17 -0700569 }
570 /*
571 * In any case we need to clean the dirty flag and we must
572 * do it under the buffer lock to be sure we don't race
573 * with running write-out.
574 */
Jan Kara1e9fd532009-06-24 17:31:40 +0200575 JBUFFER_TRACE(jh, "Journalling dirty buffer");
576 clear_buffer_dirty(bh);
577 set_buffer_jbddirty(bh);
Dave Kleikampe9ad5622006-09-27 01:49:35 -0700578 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579
580 unlock_buffer(bh);
581
582 error = -EROFS;
583 if (is_handle_aborted(handle)) {
584 jbd_unlock_bh_state(bh);
585 goto out;
586 }
587 error = 0;
588
589 /*
590 * The buffer is already part of this transaction if b_transaction or
591 * b_next_transaction points to it
592 */
593 if (jh->b_transaction == transaction ||
594 jh->b_next_transaction == transaction)
595 goto done;
596
597 /*
Josef Bacik5bc833f2008-04-28 02:16:10 -0700598 * this is the first time this transaction is touching this buffer,
599 * reset the modified flag
600 */
601 jh->b_modified = 0;
602
603 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700604 * If there is already a copy-out version of this buffer, then we don't
605 * need to make another one
606 */
607 if (jh->b_frozen_data) {
608 JBUFFER_TRACE(jh, "has frozen data");
609 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
610 jh->b_next_transaction = transaction;
611 goto done;
612 }
613
614 /* Is there data here we need to preserve? */
615
616 if (jh->b_transaction && jh->b_transaction != transaction) {
617 JBUFFER_TRACE(jh, "owned by older transaction");
618 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
619 J_ASSERT_JH(jh, jh->b_transaction ==
620 journal->j_committing_transaction);
621
622 /* There is one case we have to be very careful about.
623 * If the committing transaction is currently writing
624 * this buffer out to disk and has NOT made a copy-out,
625 * then we cannot modify the buffer contents at all
626 * right now. The essence of copy-out is that it is the
627 * extra copy, not the primary copy, which gets
628 * journaled. If the primary copy is already going to
629 * disk then we cannot do copy-out here. */
630
631 if (jh->b_jlist == BJ_Shadow) {
632 DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
633 wait_queue_head_t *wqh;
634
635 wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
636
637 JBUFFER_TRACE(jh, "on shadow: sleep");
638 jbd_unlock_bh_state(bh);
639 /* commit wakes up all shadow buffers after IO */
640 for ( ; ; ) {
641 prepare_to_wait(wqh, &wait.wait,
642 TASK_UNINTERRUPTIBLE);
643 if (jh->b_jlist != BJ_Shadow)
644 break;
645 schedule();
646 }
647 finish_wait(wqh, &wait.wait);
648 goto repeat;
649 }
650
651 /* Only do the copy if the currently-owning transaction
652 * still needs it. If it is on the Forget list, the
653 * committing transaction is past that stage. The
654 * buffer had better remain locked during the kmalloc,
655 * but that should be true --- we hold the journal lock
656 * still and the buffer is already on the BUF_JOURNAL
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700657 * list so won't be flushed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700658 *
659 * Subtle point, though: if this is a get_undo_access,
660 * then we will be relying on the frozen_data to contain
661 * the new value of the committed_data record after the
662 * transaction, so we HAVE to force the frozen_data copy
663 * in that case. */
664
665 if (jh->b_jlist != BJ_Forget || force_copy) {
666 JBUFFER_TRACE(jh, "generate frozen data");
667 if (!frozen_buffer) {
668 JBUFFER_TRACE(jh, "allocate memory for buffer");
669 jbd_unlock_bh_state(bh);
Badari Pulavartyea817392006-08-27 01:23:52 -0700670 frozen_buffer =
Mingming Caoc089d492007-10-16 18:38:25 -0400671 jbd_alloc(jh2bh(jh)->b_size,
Badari Pulavartyea817392006-08-27 01:23:52 -0700672 GFP_NOFS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 if (!frozen_buffer) {
674 printk(KERN_EMERG
675 "%s: OOM for frozen_buffer\n",
Harvey Harrison08fc99b2008-04-28 02:16:16 -0700676 __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677 JBUFFER_TRACE(jh, "oom!");
678 error = -ENOMEM;
679 jbd_lock_bh_state(bh);
680 goto done;
681 }
682 goto repeat;
683 }
684 jh->b_frozen_data = frozen_buffer;
685 frozen_buffer = NULL;
686 need_copy = 1;
687 }
688 jh->b_next_transaction = transaction;
689 }
690
691
692 /*
693 * Finally, if the buffer is not journaled right now, we need to make
694 * sure it doesn't get written to disk before the caller actually
695 * commits the new data
696 */
697 if (!jh->b_transaction) {
698 JBUFFER_TRACE(jh, "no transaction");
699 J_ASSERT_JH(jh, !jh->b_next_transaction);
700 jh->b_transaction = transaction;
701 JBUFFER_TRACE(jh, "file as BJ_Reserved");
702 spin_lock(&journal->j_list_lock);
703 __journal_file_buffer(jh, transaction, BJ_Reserved);
704 spin_unlock(&journal->j_list_lock);
705 }
706
707done:
708 if (need_copy) {
709 struct page *page;
710 int offset;
711 char *source;
712
713 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
714 "Possible IO failure.\n");
715 page = jh2bh(jh)->b_page;
716 offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK;
717 source = kmap_atomic(page, KM_USER0);
718 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
719 kunmap_atomic(source, KM_USER0);
720 }
721 jbd_unlock_bh_state(bh);
722
723 /*
724 * If we are about to journal a buffer, then any revoke pending on it is
725 * no longer valid
726 */
727 journal_cancel_revoke(handle, jh);
728
729out:
Andrew Morton304c4c82006-06-23 02:05:31 -0700730 if (unlikely(frozen_buffer)) /* It's usually NULL */
Mingming Caoc089d492007-10-16 18:38:25 -0400731 jbd_free(frozen_buffer, bh->b_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732
733 JBUFFER_TRACE(jh, "exit");
734 return error;
735}
736
737/**
738 * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
739 * @handle: transaction to add buffer modifications to
740 * @bh: bh to be used for metadata writes
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741 *
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) {
Jan Kara1e9fd532009-06-24 17:31:40 +0200813 /*
814 * Previous journal_forget() could have left the buffer
815 * with jbddirty bit set because it was being committed. When
816 * the commit finished, we've filed the buffer for
817 * checkpointing and marked it dirty. Now we are reallocating
818 * the buffer so the transaction freeing it must have
819 * committed and so it's safe to clear the dirty bit.
820 */
821 clear_buffer_dirty(jh2bh(jh));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 jh->b_transaction = transaction;
Josef Bacik5bc833f2008-04-28 02:16:10 -0700823
824 /* first access by this transaction */
825 jh->b_modified = 0;
826
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827 JBUFFER_TRACE(jh, "file as BJ_Reserved");
828 __journal_file_buffer(jh, transaction, BJ_Reserved);
829 } else if (jh->b_transaction == journal->j_committing_transaction) {
Josef Bacik5bc833f2008-04-28 02:16:10 -0700830 /* first access by this transaction */
831 jh->b_modified = 0;
832
Linus Torvalds1da177e2005-04-16 15:20:36 -0700833 JBUFFER_TRACE(jh, "set next transaction");
834 jh->b_next_transaction = transaction;
835 }
836 spin_unlock(&journal->j_list_lock);
837 jbd_unlock_bh_state(bh);
838
839 /*
840 * akpm: I added this. ext3_alloc_branch can pick up new indirect
841 * blocks which contain freed but then revoked metadata. We need
842 * to cancel the revoke in case we end up freeing it yet again
843 * and the reallocating as data - this would cause a second revoke,
844 * which hits an assertion error.
845 */
846 JBUFFER_TRACE(jh, "cancelling revoke");
847 journal_cancel_revoke(handle, jh);
848 journal_put_journal_head(jh);
849out:
850 return err;
851}
852
853/**
Randy Dunlap78a4a502008-02-29 22:02:31 -0800854 * int journal_get_undo_access() - Notify intent to modify metadata with non-rewindable consequences
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 * @handle: transaction
856 * @bh: buffer to undo
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857 *
858 * Sometimes there is a need to distinguish between metadata which has
859 * been committed to disk and that which has not. The ext3fs code uses
860 * this for freeing and allocating space, we have to make sure that we
861 * do not reuse freed space until the deallocation has been committed,
862 * since if we overwrote that space we would make the delete
863 * un-rewindable in case of a crash.
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700864 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865 * To deal with that, journal_get_undo_access requests write access to a
866 * buffer for parts of non-rewindable operations such as delete
867 * operations on the bitmaps. The journaling code must keep a copy of
868 * the buffer's contents prior to the undo_access call until such time
869 * as we know that the buffer has definitely been committed to disk.
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700870 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700871 * We never need to know which transaction the committed data is part
872 * of, buffers touched here are guaranteed to be dirtied later and so
873 * will be committed to a new transaction in due course, at which point
874 * we can discard the old committed data pointer.
875 *
876 * Returns error number or 0 on success.
877 */
878int journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
879{
880 int err;
881 struct journal_head *jh = journal_add_journal_head(bh);
882 char *committed_data = NULL;
883
884 JBUFFER_TRACE(jh, "entry");
885
886 /*
887 * Do this first --- it can drop the journal lock, so we want to
888 * make sure that obtaining the committed_data is done
889 * atomically wrt. completion of any outstanding commits.
890 */
891 err = do_get_write_access(handle, jh, 1);
892 if (err)
893 goto out;
894
895repeat:
896 if (!jh->b_committed_data) {
Mingming Caoc089d492007-10-16 18:38:25 -0400897 committed_data = jbd_alloc(jh2bh(jh)->b_size, GFP_NOFS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700898 if (!committed_data) {
899 printk(KERN_EMERG "%s: No memory for committed data\n",
Harvey Harrison08fc99b2008-04-28 02:16:16 -0700900 __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 err = -ENOMEM;
902 goto out;
903 }
904 }
905
906 jbd_lock_bh_state(bh);
907 if (!jh->b_committed_data) {
908 /* Copy out the current buffer contents into the
909 * preserved, committed copy. */
910 JBUFFER_TRACE(jh, "generate b_committed data");
911 if (!committed_data) {
912 jbd_unlock_bh_state(bh);
913 goto repeat;
914 }
915
916 jh->b_committed_data = committed_data;
917 committed_data = NULL;
918 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
919 }
920 jbd_unlock_bh_state(bh);
921out:
922 journal_put_journal_head(jh);
Andrew Morton304c4c82006-06-23 02:05:31 -0700923 if (unlikely(committed_data))
Mingming Caoc089d492007-10-16 18:38:25 -0400924 jbd_free(committed_data, bh->b_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925 return err;
926}
927
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700928/**
Randy Dunlap78a4a502008-02-29 22:02:31 -0800929 * int journal_dirty_data() - mark a buffer as containing dirty data to be flushed
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930 * @handle: transaction
931 * @bh: bufferhead to mark
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700932 *
Randy Dunlap78a4a502008-02-29 22:02:31 -0800933 * Description:
934 * Mark a buffer as containing dirty data which needs to be flushed before
935 * we can commit the current transaction.
936 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700937 * The buffer is placed on the transaction's data list and is marked as
938 * belonging to the transaction.
939 *
940 * Returns error number or 0 on success.
941 *
942 * journal_dirty_data() can be called via page_launder->ext3_writepage
943 * by kswapd.
944 */
945int journal_dirty_data(handle_t *handle, struct buffer_head *bh)
946{
947 journal_t *journal = handle->h_transaction->t_journal;
948 int need_brelse = 0;
949 struct journal_head *jh;
Hidehiro Kawai960a22a2008-10-18 20:27:58 -0700950 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951
952 if (is_handle_aborted(handle))
Hidehiro Kawai960a22a2008-10-18 20:27:58 -0700953 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954
955 jh = journal_add_journal_head(bh);
956 JBUFFER_TRACE(jh, "entry");
957
958 /*
959 * The buffer could *already* be dirty. Writeout can start
960 * at any time.
961 */
962 jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
963
964 /*
965 * What if the buffer is already part of a running transaction?
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700966 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700967 * There are two cases:
968 * 1) It is part of the current running transaction. Refile it,
969 * just in case we have allocated it as metadata, deallocated
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700970 * it, then reallocated it as data.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700971 * 2) It is part of the previous, still-committing transaction.
972 * If all we want to do is to guarantee that the buffer will be
973 * written to disk before this new transaction commits, then
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700974 * being sure that the *previous* transaction has this same
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975 * property is sufficient for us! Just leave it on its old
976 * transaction.
977 *
978 * In case (2), the buffer must not already exist as metadata
979 * --- that would violate write ordering (a transaction is free
980 * to write its data at any point, even before the previous
981 * committing transaction has committed). The caller must
982 * never, ever allow this to happen: there's nothing we can do
983 * about it in this layer.
984 */
985 jbd_lock_bh_state(bh);
986 spin_lock(&journal->j_list_lock);
Eric Sandeenf58a74d2006-10-28 10:38:27 -0700987
988 /* Now that we have bh_state locked, are we really still mapped? */
989 if (!buffer_mapped(bh)) {
990 JBUFFER_TRACE(jh, "unmapped buffer, bailing out");
991 goto no_journal;
992 }
993
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994 if (jh->b_transaction) {
995 JBUFFER_TRACE(jh, "has transaction");
996 if (jh->b_transaction != handle->h_transaction) {
997 JBUFFER_TRACE(jh, "belongs to older transaction");
998 J_ASSERT_JH(jh, jh->b_transaction ==
999 journal->j_committing_transaction);
1000
1001 /* @@@ IS THIS TRUE ? */
1002 /*
1003 * Not any more. Scenario: someone does a write()
1004 * in data=journal mode. The buffer's transaction has
1005 * moved into commit. Then someone does another
1006 * write() to the file. We do the frozen data copyout
1007 * and set b_next_transaction to point to j_running_t.
1008 * And while we're in that state, someone does a
1009 * writepage() in an attempt to pageout the same area
1010 * of the file via a shared mapping. At present that
1011 * calls journal_dirty_data(), and we get right here.
1012 * It may be too late to journal the data. Simply
1013 * falling through to the next test will suffice: the
1014 * data will be dirty and wil be checkpointed. The
1015 * ordering comments in the next comment block still
1016 * apply.
1017 */
1018 //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1019
1020 /*
1021 * If we're journalling data, and this buffer was
1022 * subject to a write(), it could be metadata, forget
1023 * or shadow against the committing transaction. Now,
1024 * someone has dirtied the same darn page via a mapping
1025 * and it is being writepage()'d.
1026 * We *could* just steal the page from commit, with some
1027 * fancy locking there. Instead, we just skip it -
1028 * don't tie the page's buffers to the new transaction
1029 * at all.
1030 * Implication: if we crash before the writepage() data
1031 * is written into the filesystem, recovery will replay
1032 * the write() data.
1033 */
1034 if (jh->b_jlist != BJ_None &&
1035 jh->b_jlist != BJ_SyncData &&
1036 jh->b_jlist != BJ_Locked) {
1037 JBUFFER_TRACE(jh, "Not stealing");
1038 goto no_journal;
1039 }
1040
1041 /*
1042 * This buffer may be undergoing writeout in commit. We
1043 * can't return from here and let the caller dirty it
1044 * again because that can cause the write-out loop in
1045 * commit to never terminate.
1046 */
1047 if (buffer_dirty(bh)) {
1048 get_bh(bh);
1049 spin_unlock(&journal->j_list_lock);
1050 jbd_unlock_bh_state(bh);
1051 need_brelse = 1;
1052 sync_dirty_buffer(bh);
1053 jbd_lock_bh_state(bh);
1054 spin_lock(&journal->j_list_lock);
Eric Sandeenf58a74d2006-10-28 10:38:27 -07001055 /* Since we dropped the lock... */
1056 if (!buffer_mapped(bh)) {
1057 JBUFFER_TRACE(jh, "buffer got unmapped");
1058 goto no_journal;
1059 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060 /* The buffer may become locked again at any
1061 time if it is redirtied */
1062 }
1063
Hidehiro Kawai960a22a2008-10-18 20:27:58 -07001064 /*
1065 * We cannot remove the buffer with io error from the
1066 * committing transaction, because otherwise it would
1067 * miss the error and the commit would not abort.
1068 */
1069 if (unlikely(!buffer_uptodate(bh))) {
1070 ret = -EIO;
1071 goto no_journal;
1072 }
1073
Linus Torvalds1da177e2005-04-16 15:20:36 -07001074 if (jh->b_transaction != NULL) {
1075 JBUFFER_TRACE(jh, "unfile from commit");
1076 __journal_temp_unlink_buffer(jh);
1077 /* It still points to the committing
1078 * transaction; move it to this one so
1079 * that the refile assert checks are
1080 * happy. */
1081 jh->b_transaction = handle->h_transaction;
1082 }
1083 /* The buffer will be refiled below */
1084
1085 }
1086 /*
1087 * Special case --- the buffer might actually have been
1088 * allocated and then immediately deallocated in the previous,
1089 * committing transaction, so might still be left on that
1090 * transaction's metadata lists.
1091 */
1092 if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
1093 JBUFFER_TRACE(jh, "not on correct data list: unfile");
1094 J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
1095 __journal_temp_unlink_buffer(jh);
1096 jh->b_transaction = handle->h_transaction;
1097 JBUFFER_TRACE(jh, "file as data");
1098 __journal_file_buffer(jh, handle->h_transaction,
1099 BJ_SyncData);
1100 }
1101 } else {
1102 JBUFFER_TRACE(jh, "not on a transaction");
1103 __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
1104 }
1105no_journal:
1106 spin_unlock(&journal->j_list_lock);
1107 jbd_unlock_bh_state(bh);
1108 if (need_brelse) {
1109 BUFFER_TRACE(bh, "brelse");
1110 __brelse(bh);
1111 }
1112 JBUFFER_TRACE(jh, "exit");
1113 journal_put_journal_head(jh);
Hidehiro Kawai960a22a2008-10-18 20:27:58 -07001114 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001115}
1116
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001117/**
Randy Dunlap78a4a502008-02-29 22:02:31 -08001118 * int journal_dirty_metadata() - mark a buffer as containing dirty metadata
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119 * @handle: transaction to add buffer to.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001120 * @bh: buffer to mark
1121 *
Randy Dunlap78a4a502008-02-29 22:02:31 -08001122 * Mark dirty metadata which needs to be journaled as part of the current
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123 * transaction.
1124 *
1125 * The buffer is placed on the transaction's metadata list and is marked
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001126 * as belonging to the transaction.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001127 *
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001128 * Returns error number or 0 on success.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129 *
1130 * Special care needs to be taken if the buffer already belongs to the
1131 * current committing transaction (in which case we should have frozen
1132 * data present for that commit). In that case, we don't relink the
1133 * buffer: that only gets done when the old transaction finally
1134 * completes its commit.
1135 */
1136int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1137{
1138 transaction_t *transaction = handle->h_transaction;
1139 journal_t *journal = transaction->t_journal;
1140 struct journal_head *jh = bh2jh(bh);
1141
1142 jbd_debug(5, "journal_head %p\n", jh);
1143 JBUFFER_TRACE(jh, "entry");
1144 if (is_handle_aborted(handle))
1145 goto out;
1146
1147 jbd_lock_bh_state(bh);
1148
1149 if (jh->b_modified == 0) {
1150 /*
1151 * This buffer's got modified and becoming part
1152 * of the transaction. This needs to be done
1153 * once a transaction -bzzz
1154 */
1155 jh->b_modified = 1;
1156 J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
1157 handle->h_buffer_credits--;
1158 }
1159
1160 /*
1161 * fastpath, to avoid expensive locking. If this buffer is already
1162 * on the running transaction's metadata list there is nothing to do.
1163 * Nobody can take it off again because there is a handle open.
1164 * I _think_ we're OK here with SMP barriers - a mistaken decision will
1165 * result in this test being false, so we go in and take the locks.
1166 */
1167 if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1168 JBUFFER_TRACE(jh, "fastpath");
1169 J_ASSERT_JH(jh, jh->b_transaction ==
1170 journal->j_running_transaction);
1171 goto out_unlock_bh;
1172 }
1173
1174 set_buffer_jbddirty(bh);
1175
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001176 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177 * Metadata already on the current transaction list doesn't
1178 * need to be filed. Metadata on another transaction's list must
1179 * be committing, and will be refiled once the commit completes:
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001180 * leave it alone for now.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181 */
1182 if (jh->b_transaction != transaction) {
1183 JBUFFER_TRACE(jh, "already on other transaction");
1184 J_ASSERT_JH(jh, jh->b_transaction ==
1185 journal->j_committing_transaction);
1186 J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
1187 /* And this case is illegal: we can't reuse another
1188 * transaction's data buffer, ever. */
1189 goto out_unlock_bh;
1190 }
1191
1192 /* That test should have eliminated the following case: */
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001193 J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001194
1195 JBUFFER_TRACE(jh, "file as BJ_Metadata");
1196 spin_lock(&journal->j_list_lock);
1197 __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1198 spin_unlock(&journal->j_list_lock);
1199out_unlock_bh:
1200 jbd_unlock_bh_state(bh);
1201out:
1202 JBUFFER_TRACE(jh, "exit");
1203 return 0;
1204}
1205
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001206/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207 * journal_release_buffer: undo a get_write_access without any buffer
1208 * updates, if the update decided in the end that it didn't need access.
1209 *
1210 */
1211void
1212journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1213{
1214 BUFFER_TRACE(bh, "entry");
1215}
1216
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001217/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218 * void journal_forget() - bforget() for potentially-journaled buffers.
1219 * @handle: transaction handle
1220 * @bh: bh to 'forget'
1221 *
1222 * We can only do the bforget if there are no commits pending against the
1223 * buffer. If the buffer is dirty in the current running transaction we
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001224 * can safely unlink it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001225 *
1226 * bh may not be a journalled buffer at all - it may be a non-JBD
1227 * buffer which came off the hashtable. Check for this.
1228 *
1229 * Decrements bh->b_count by one.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001230 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001231 * Allow this call even if the handle has aborted --- it may be part of
1232 * the caller's cleanup after an abort.
1233 */
1234int journal_forget (handle_t *handle, struct buffer_head *bh)
1235{
1236 transaction_t *transaction = handle->h_transaction;
1237 journal_t *journal = transaction->t_journal;
1238 struct journal_head *jh;
1239 int drop_reserve = 0;
1240 int err = 0;
Josef Bacik5b9a4992008-04-28 02:16:12 -07001241 int was_modified = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242
1243 BUFFER_TRACE(bh, "entry");
1244
1245 jbd_lock_bh_state(bh);
1246 spin_lock(&journal->j_list_lock);
1247
1248 if (!buffer_jbd(bh))
1249 goto not_jbd;
1250 jh = bh2jh(bh);
1251
1252 /* Critical error: attempting to delete a bitmap buffer, maybe?
1253 * Don't do any jbd operations, and return an error. */
1254 if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1255 "inconsistent data on disk")) {
1256 err = -EIO;
1257 goto not_jbd;
1258 }
1259
Josef Bacik5b9a4992008-04-28 02:16:12 -07001260 /* keep track of wether or not this transaction modified us */
1261 was_modified = jh->b_modified;
1262
Linus Torvalds1da177e2005-04-16 15:20:36 -07001263 /*
1264 * The buffer's going from the transaction, we must drop
1265 * all references -bzzz
1266 */
1267 jh->b_modified = 0;
1268
1269 if (jh->b_transaction == handle->h_transaction) {
1270 J_ASSERT_JH(jh, !jh->b_frozen_data);
1271
1272 /* If we are forgetting a buffer which is already part
1273 * of this transaction, then we can just drop it from
1274 * the transaction immediately. */
1275 clear_buffer_dirty(bh);
1276 clear_buffer_jbddirty(bh);
1277
1278 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1279
Josef Bacik5b9a4992008-04-28 02:16:12 -07001280 /*
1281 * we only want to drop a reference if this transaction
1282 * modified the buffer
1283 */
1284 if (was_modified)
1285 drop_reserve = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001287 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001288 * We are no longer going to journal this buffer.
1289 * However, the commit of this transaction is still
1290 * important to the buffer: the delete that we are now
1291 * processing might obsolete an old log entry, so by
1292 * committing, we can satisfy the buffer's checkpoint.
1293 *
1294 * So, if we have a checkpoint on the buffer, we should
1295 * now refile the buffer on our BJ_Forget list so that
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001296 * we know to remove the checkpoint after we commit.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001297 */
1298
1299 if (jh->b_cp_transaction) {
1300 __journal_temp_unlink_buffer(jh);
1301 __journal_file_buffer(jh, transaction, BJ_Forget);
1302 } else {
1303 __journal_unfile_buffer(jh);
1304 journal_remove_journal_head(bh);
1305 __brelse(bh);
1306 if (!buffer_jbd(bh)) {
1307 spin_unlock(&journal->j_list_lock);
1308 jbd_unlock_bh_state(bh);
1309 __bforget(bh);
1310 goto drop;
1311 }
1312 }
1313 } else if (jh->b_transaction) {
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001314 J_ASSERT_JH(jh, (jh->b_transaction ==
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315 journal->j_committing_transaction));
1316 /* However, if the buffer is still owned by a prior
1317 * (committing) transaction, we can't drop it yet... */
1318 JBUFFER_TRACE(jh, "belongs to older transaction");
1319 /* ... but we CAN drop it from the new transaction if we
1320 * have also modified it since the original commit. */
1321
1322 if (jh->b_next_transaction) {
1323 J_ASSERT(jh->b_next_transaction == transaction);
1324 jh->b_next_transaction = NULL;
Josef Bacik5b9a4992008-04-28 02:16:12 -07001325
1326 /*
1327 * only drop a reference if this transaction modified
1328 * the buffer
1329 */
1330 if (was_modified)
1331 drop_reserve = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332 }
1333 }
1334
1335not_jbd:
1336 spin_unlock(&journal->j_list_lock);
1337 jbd_unlock_bh_state(bh);
1338 __brelse(bh);
1339drop:
1340 if (drop_reserve) {
1341 /* no need to reserve log space for this block -bzzz */
1342 handle->h_buffer_credits++;
1343 }
1344 return err;
1345}
1346
1347/**
1348 * int journal_stop() - complete a transaction
1349 * @handle: tranaction to complete.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001350 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351 * All done for a particular handle.
1352 *
1353 * There is not much action needed here. We just return any remaining
1354 * buffer credits to the transaction and remove the handle. The only
1355 * complication is that we need to start a commit operation if the
1356 * filesystem is marked for synchronous update.
1357 *
1358 * journal_stop itself will not usually return an error, but it may
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001359 * do so in unusual circumstances. In particular, expect it to
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360 * return -EIO if a journal_abort has been executed since the
1361 * transaction began.
1362 */
1363int journal_stop(handle_t *handle)
1364{
1365 transaction_t *transaction = handle->h_transaction;
1366 journal_t *journal = transaction->t_journal;
Josef Bacikf420d4d2009-01-07 18:07:24 -08001367 int err;
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001368 pid_t pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370 J_ASSERT(journal_current_handle() == handle);
1371
1372 if (is_handle_aborted(handle))
1373 err = -EIO;
OGAWA Hirofumi3e2a5322006-10-19 23:29:11 -07001374 else {
1375 J_ASSERT(transaction->t_updates > 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 err = 0;
OGAWA Hirofumi3e2a5322006-10-19 23:29:11 -07001377 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001378
1379 if (--handle->h_ref > 0) {
1380 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1381 handle->h_ref);
1382 return err;
1383 }
1384
1385 jbd_debug(4, "Handle %p going down\n", handle);
1386
1387 /*
1388 * Implement synchronous transaction batching. If the handle
1389 * was synchronous, don't force a commit immediately. Let's
1390 * yield and let another thread piggyback onto this transaction.
1391 * Keep doing that while new threads continue to arrive.
1392 * It doesn't cost much - we're about to run a commit and sleep
1393 * on IO anyway. Speeds up many-threaded, many-dir operations
1394 * by 30x or more...
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001395 *
Josef Bacikf420d4d2009-01-07 18:07:24 -08001396 * We try and optimize the sleep time against what the underlying disk
1397 * can do, instead of having a static sleep time. This is usefull for
1398 * the case where our storage is so fast that it is more optimal to go
1399 * ahead and force a flush and wait for the transaction to be committed
1400 * than it is to wait for an arbitrary amount of time for new writers to
1401 * join the transaction. We acheive this by measuring how long it takes
1402 * to commit a transaction, and compare it with how long this
1403 * transaction has been running, and if run time < commit time then we
1404 * sleep for the delta and commit. This greatly helps super fast disks
1405 * that would see slowdowns as more threads started doing fsyncs.
1406 *
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001407 * But don't do this if this process was the most recent one to
1408 * perform a synchronous write. We do this to detect the case where a
1409 * single process is doing a stream of sync writes. No point in waiting
1410 * for joiners in that case.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001411 */
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001412 pid = current->pid;
1413 if (handle->h_sync && journal->j_last_sync_writer != pid) {
Josef Bacikf420d4d2009-01-07 18:07:24 -08001414 u64 commit_time, trans_time;
1415
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001416 journal->j_last_sync_writer = pid;
Josef Bacikf420d4d2009-01-07 18:07:24 -08001417
1418 spin_lock(&journal->j_state_lock);
1419 commit_time = journal->j_average_commit_time;
1420 spin_unlock(&journal->j_state_lock);
1421
1422 trans_time = ktime_to_ns(ktime_sub(ktime_get(),
1423 transaction->t_start_time));
1424
1425 commit_time = min_t(u64, commit_time,
1426 1000*jiffies_to_usecs(1));
1427
1428 if (trans_time < commit_time) {
1429 ktime_t expires = ktime_add_ns(ktime_get(),
1430 commit_time);
1431 set_current_state(TASK_UNINTERRUPTIBLE);
1432 schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
1433 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001434 }
1435
Theodore Ts'o512a0042009-03-27 22:14:27 -04001436 if (handle->h_sync)
1437 transaction->t_synchronous_commit = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438 current->journal_info = NULL;
1439 spin_lock(&journal->j_state_lock);
1440 spin_lock(&transaction->t_handle_lock);
1441 transaction->t_outstanding_credits -= handle->h_buffer_credits;
1442 transaction->t_updates--;
1443 if (!transaction->t_updates) {
1444 wake_up(&journal->j_wait_updates);
1445 if (journal->j_barrier_count)
1446 wake_up(&journal->j_wait_transaction_locked);
1447 }
1448
1449 /*
1450 * If the handle is marked SYNC, we need to set another commit
1451 * going! We also want to force a commit if the current
1452 * transaction is occupying too much of the log, or if the
1453 * transaction is too old now.
1454 */
1455 if (handle->h_sync ||
1456 transaction->t_outstanding_credits >
1457 journal->j_max_transaction_buffers ||
Dave Kleikampe9ad5622006-09-27 01:49:35 -07001458 time_after_eq(jiffies, transaction->t_expires)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459 /* Do this even for aborted journals: an abort still
1460 * completes the commit thread, it just doesn't write
1461 * anything to disk. */
1462 tid_t tid = transaction->t_tid;
1463
1464 spin_unlock(&transaction->t_handle_lock);
1465 jbd_debug(2, "transaction too old, requesting commit for "
1466 "handle %p\n", handle);
1467 /* This is non-blocking */
1468 __log_start_commit(journal, transaction->t_tid);
1469 spin_unlock(&journal->j_state_lock);
1470
1471 /*
1472 * Special case: JFS_SYNC synchronous updates require us
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001473 * to wait for the commit to complete.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001474 */
1475 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1476 err = log_wait_commit(journal, tid);
1477 } else {
1478 spin_unlock(&transaction->t_handle_lock);
1479 spin_unlock(&journal->j_state_lock);
1480 }
1481
Ingo Molnar3295f0e2008-08-11 10:30:30 +02001482 lock_map_release(&handle->h_lockdep_map);
Peter Zijlstra34a3d1e2007-10-11 22:11:12 +02001483
Linus Torvalds1da177e2005-04-16 15:20:36 -07001484 jbd_free_handle(handle);
1485 return err;
1486}
1487
Randy Dunlap0cf01f62008-03-19 17:00:44 -07001488/**
1489 * int journal_force_commit() - force any uncommitted transactions
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 * @journal: journal to force
1491 *
1492 * For synchronous operations: force any uncommitted transactions
1493 * to disk. May seem kludgy, but it reuses all the handle batching
1494 * code in a very simple manner.
1495 */
1496int journal_force_commit(journal_t *journal)
1497{
1498 handle_t *handle;
1499 int ret;
1500
1501 handle = journal_start(journal, 1);
1502 if (IS_ERR(handle)) {
1503 ret = PTR_ERR(handle);
1504 } else {
1505 handle->h_sync = 1;
1506 ret = journal_stop(handle);
1507 }
1508 return ret;
1509}
1510
1511/*
1512 *
1513 * List management code snippets: various functions for manipulating the
1514 * transaction buffer lists.
1515 *
1516 */
1517
1518/*
1519 * Append a buffer to a transaction list, given the transaction's list head
1520 * pointer.
1521 *
1522 * j_list_lock is held.
1523 *
1524 * jbd_lock_bh_state(jh2bh(jh)) is held.
1525 */
1526
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001527static inline void
Linus Torvalds1da177e2005-04-16 15:20:36 -07001528__blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1529{
1530 if (!*list) {
1531 jh->b_tnext = jh->b_tprev = jh;
1532 *list = jh;
1533 } else {
1534 /* Insert at the tail of the list to preserve order */
1535 struct journal_head *first = *list, *last = first->b_tprev;
1536 jh->b_tprev = last;
1537 jh->b_tnext = first;
1538 last->b_tnext = first->b_tprev = jh;
1539 }
1540}
1541
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001542/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001543 * Remove a buffer from a transaction list, given the transaction's list
1544 * head pointer.
1545 *
1546 * Called with j_list_lock held, and the journal may not be locked.
1547 *
1548 * jbd_lock_bh_state(jh2bh(jh)) is held.
1549 */
1550
1551static inline void
1552__blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1553{
1554 if (*list == jh) {
1555 *list = jh->b_tnext;
1556 if (*list == jh)
1557 *list = NULL;
1558 }
1559 jh->b_tprev->b_tnext = jh->b_tnext;
1560 jh->b_tnext->b_tprev = jh->b_tprev;
1561}
1562
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001563/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001564 * Remove a buffer from the appropriate transaction list.
1565 *
1566 * Note that this function can *change* the value of
1567 * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
1568 * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller
1569 * is holding onto a copy of one of thee pointers, it could go bad.
1570 * Generally the caller needs to re-read the pointer from the transaction_t.
1571 *
1572 * Called under j_list_lock. The journal may not be locked.
1573 */
Adrian Bunkd394e122006-12-06 20:38:26 -08001574static void __journal_temp_unlink_buffer(struct journal_head *jh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001575{
1576 struct journal_head **list = NULL;
1577 transaction_t *transaction;
1578 struct buffer_head *bh = jh2bh(jh);
1579
1580 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1581 transaction = jh->b_transaction;
1582 if (transaction)
1583 assert_spin_locked(&transaction->t_journal->j_list_lock);
1584
1585 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1586 if (jh->b_jlist != BJ_None)
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001587 J_ASSERT_JH(jh, transaction != NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001588
1589 switch (jh->b_jlist) {
1590 case BJ_None:
1591 return;
1592 case BJ_SyncData:
1593 list = &transaction->t_sync_datalist;
1594 break;
1595 case BJ_Metadata:
1596 transaction->t_nr_buffers--;
1597 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1598 list = &transaction->t_buffers;
1599 break;
1600 case BJ_Forget:
1601 list = &transaction->t_forget;
1602 break;
1603 case BJ_IO:
1604 list = &transaction->t_iobuf_list;
1605 break;
1606 case BJ_Shadow:
1607 list = &transaction->t_shadow_list;
1608 break;
1609 case BJ_LogCtl:
1610 list = &transaction->t_log_list;
1611 break;
1612 case BJ_Reserved:
1613 list = &transaction->t_reserved_list;
1614 break;
1615 case BJ_Locked:
1616 list = &transaction->t_locked_list;
1617 break;
1618 }
1619
1620 __blist_del_buffer(list, jh);
1621 jh->b_jlist = BJ_None;
1622 if (test_clear_buffer_jbddirty(bh))
1623 mark_buffer_dirty(bh); /* Expose it to the VM */
1624}
1625
1626void __journal_unfile_buffer(struct journal_head *jh)
1627{
1628 __journal_temp_unlink_buffer(jh);
1629 jh->b_transaction = NULL;
1630}
1631
1632void journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1633{
1634 jbd_lock_bh_state(jh2bh(jh));
1635 spin_lock(&journal->j_list_lock);
1636 __journal_unfile_buffer(jh);
1637 spin_unlock(&journal->j_list_lock);
1638 jbd_unlock_bh_state(jh2bh(jh));
1639}
1640
1641/*
1642 * Called from journal_try_to_free_buffers().
1643 *
1644 * Called under jbd_lock_bh_state(bh)
1645 */
1646static void
1647__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1648{
1649 struct journal_head *jh;
1650
1651 jh = bh2jh(bh);
1652
1653 if (buffer_locked(bh) || buffer_dirty(bh))
1654 goto out;
1655
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001656 if (jh->b_next_transaction != NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001657 goto out;
1658
1659 spin_lock(&journal->j_list_lock);
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001660 if (jh->b_transaction != NULL && jh->b_cp_transaction == NULL) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001661 if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
1662 /* A written-back ordered data buffer */
1663 JBUFFER_TRACE(jh, "release data");
1664 __journal_unfile_buffer(jh);
1665 journal_remove_journal_head(bh);
1666 __brelse(bh);
1667 }
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001668 } else if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001669 /* written-back checkpointed metadata buffer */
1670 if (jh->b_jlist == BJ_None) {
1671 JBUFFER_TRACE(jh, "remove from checkpoint list");
1672 __journal_remove_checkpoint(jh);
1673 journal_remove_journal_head(bh);
1674 __brelse(bh);
1675 }
1676 }
1677 spin_unlock(&journal->j_list_lock);
1678out:
1679 return;
1680}
1681
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001682/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683 * int journal_try_to_free_buffers() - try to free page buffers.
1684 * @journal: journal for operation
1685 * @page: to try and free
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001686 * @gfp_mask: we use the mask to detect how hard should we try to release
1687 * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to
1688 * release the buffers.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001689 *
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001690 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001691 * For all the buffers on this page,
1692 * if they are fully written out ordered data, move them onto BUF_CLEAN
1693 * so try_to_free_buffers() can reap them.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001694 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001695 * This function returns non-zero if we wish try_to_free_buffers()
1696 * to be called. We do this if the page is releasable by try_to_free_buffers().
1697 * We also do it if the page has locked or dirty buffers and the caller wants
1698 * us to perform sync or async writeout.
1699 *
1700 * This complicates JBD locking somewhat. We aren't protected by the
1701 * BKL here. We wish to remove the buffer from its committing or
1702 * running transaction's ->t_datalist via __journal_unfile_buffer.
1703 *
1704 * This may *change* the value of transaction_t->t_datalist, so anyone
1705 * who looks at t_datalist needs to lock against this function.
1706 *
1707 * Even worse, someone may be doing a journal_dirty_data on this
1708 * buffer. So we need to lock against that. journal_dirty_data()
1709 * will come out of the lock with the buffer dirty, which makes it
1710 * ineligible for release here.
1711 *
1712 * Who else is affected by this? hmm... Really the only contender
1713 * is do_get_write_access() - it could be looking at the buffer while
1714 * journal_try_to_free_buffer() is changing its state. But that
1715 * cannot happen because we never reallocate freed data as metadata
1716 * while the data is part of a transaction. Yes?
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001717 *
1718 * Return 0 on failure, 1 on success
Linus Torvalds1da177e2005-04-16 15:20:36 -07001719 */
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001720int journal_try_to_free_buffers(journal_t *journal,
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001721 struct page *page, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001722{
1723 struct buffer_head *head;
1724 struct buffer_head *bh;
1725 int ret = 0;
1726
1727 J_ASSERT(PageLocked(page));
1728
1729 head = page_buffers(page);
1730 bh = head;
1731 do {
1732 struct journal_head *jh;
1733
1734 /*
1735 * We take our own ref against the journal_head here to avoid
1736 * having to add tons of locking around each instance of
1737 * journal_remove_journal_head() and journal_put_journal_head().
1738 */
1739 jh = journal_grab_journal_head(bh);
1740 if (!jh)
1741 continue;
1742
1743 jbd_lock_bh_state(bh);
1744 __journal_try_to_free_buffer(journal, bh);
1745 journal_put_journal_head(jh);
1746 jbd_unlock_bh_state(bh);
1747 if (buffer_jbd(bh))
1748 goto busy;
1749 } while ((bh = bh->b_this_page) != head);
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001750
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751 ret = try_to_free_buffers(page);
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001752
Linus Torvalds1da177e2005-04-16 15:20:36 -07001753busy:
1754 return ret;
1755}
1756
1757/*
1758 * This buffer is no longer needed. If it is on an older transaction's
1759 * checkpoint list we need to record it on this transaction's forget list
1760 * to pin this buffer (and hence its checkpointing transaction) down until
1761 * this transaction commits. If the buffer isn't on a checkpoint list, we
1762 * release it.
1763 * Returns non-zero if JBD no longer has an interest in the buffer.
1764 *
1765 * Called under j_list_lock.
1766 *
1767 * Called under jbd_lock_bh_state(bh).
1768 */
1769static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1770{
1771 int may_free = 1;
1772 struct buffer_head *bh = jh2bh(jh);
1773
1774 __journal_unfile_buffer(jh);
1775
1776 if (jh->b_cp_transaction) {
1777 JBUFFER_TRACE(jh, "on running+cp transaction");
Jan Kara1e9fd532009-06-24 17:31:40 +02001778 /*
1779 * We don't want to write the buffer anymore, clear the
1780 * bit so that we don't confuse checks in
1781 * __journal_file_buffer
1782 */
1783 clear_buffer_dirty(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784 __journal_file_buffer(jh, transaction, BJ_Forget);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001785 may_free = 0;
1786 } else {
1787 JBUFFER_TRACE(jh, "on running transaction");
1788 journal_remove_journal_head(bh);
1789 __brelse(bh);
1790 }
1791 return may_free;
1792}
1793
1794/*
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001795 * journal_invalidatepage
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796 *
1797 * This code is tricky. It has a number of cases to deal with.
1798 *
1799 * There are two invariants which this code relies on:
1800 *
1801 * i_size must be updated on disk before we start calling invalidatepage on the
1802 * data.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001803 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001804 * This is done in ext3 by defining an ext3_setattr method which
1805 * updates i_size before truncate gets going. By maintaining this
1806 * invariant, we can be sure that it is safe to throw away any buffers
1807 * attached to the current transaction: once the transaction commits,
1808 * we know that the data will not be needed.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001809 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810 * Note however that we can *not* throw away data belonging to the
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001811 * previous, committing transaction!
Linus Torvalds1da177e2005-04-16 15:20:36 -07001812 *
1813 * Any disk blocks which *are* part of the previous, committing
1814 * transaction (and which therefore cannot be discarded immediately) are
1815 * not going to be reused in the new running transaction
1816 *
1817 * The bitmap committed_data images guarantee this: any block which is
1818 * allocated in one transaction and removed in the next will be marked
1819 * as in-use in the committed_data bitmap, so cannot be reused until
1820 * the next transaction to delete the block commits. This means that
1821 * leaving committing buffers dirty is quite safe: the disk blocks
1822 * cannot be reallocated to a different file and so buffer aliasing is
1823 * not possible.
1824 *
1825 *
1826 * The above applies mainly to ordered data mode. In writeback mode we
1827 * don't make guarantees about the order in which data hits disk --- in
1828 * particular we don't guarantee that new dirty data is flushed before
1829 * transaction commit --- so it is always safe just to discard data
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001830 * immediately in that mode. --sct
Linus Torvalds1da177e2005-04-16 15:20:36 -07001831 */
1832
1833/*
1834 * The journal_unmap_buffer helper function returns zero if the buffer
1835 * concerned remains pinned as an anonymous buffer belonging to an older
1836 * transaction.
1837 *
1838 * We're outside-transaction here. Either or both of j_running_transaction
1839 * and j_committing_transaction may be NULL.
1840 */
1841static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1842{
1843 transaction_t *transaction;
1844 struct journal_head *jh;
1845 int may_free = 1;
1846 int ret;
1847
1848 BUFFER_TRACE(bh, "entry");
1849
1850 /*
1851 * It is safe to proceed here without the j_list_lock because the
1852 * buffers cannot be stolen by try_to_free_buffers as long as we are
1853 * holding the page lock. --sct
1854 */
1855
1856 if (!buffer_jbd(bh))
1857 goto zap_buffer_unlocked;
1858
1859 spin_lock(&journal->j_state_lock);
1860 jbd_lock_bh_state(bh);
1861 spin_lock(&journal->j_list_lock);
1862
1863 jh = journal_grab_journal_head(bh);
1864 if (!jh)
1865 goto zap_buffer_no_jh;
1866
1867 transaction = jh->b_transaction;
1868 if (transaction == NULL) {
1869 /* First case: not on any transaction. If it
1870 * has no checkpoint link, then we can zap it:
1871 * it's a writeback-mode buffer so we don't care
1872 * if it hits disk safely. */
1873 if (!jh->b_cp_transaction) {
1874 JBUFFER_TRACE(jh, "not on any transaction: zap");
1875 goto zap_buffer;
1876 }
1877
1878 if (!buffer_dirty(bh)) {
1879 /* bdflush has written it. We can drop it now */
1880 goto zap_buffer;
1881 }
1882
1883 /* OK, it must be in the journal but still not
1884 * written fully to disk: it's metadata or
1885 * journaled data... */
1886
1887 if (journal->j_running_transaction) {
1888 /* ... and once the current transaction has
1889 * committed, the buffer won't be needed any
1890 * longer. */
1891 JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1892 ret = __dispose_buffer(jh,
1893 journal->j_running_transaction);
1894 journal_put_journal_head(jh);
1895 spin_unlock(&journal->j_list_lock);
1896 jbd_unlock_bh_state(bh);
1897 spin_unlock(&journal->j_state_lock);
1898 return ret;
1899 } else {
1900 /* There is no currently-running transaction. So the
1901 * orphan record which we wrote for this file must have
1902 * passed into commit. We must attach this buffer to
1903 * the committing transaction, if it exists. */
1904 if (journal->j_committing_transaction) {
1905 JBUFFER_TRACE(jh, "give to committing trans");
1906 ret = __dispose_buffer(jh,
1907 journal->j_committing_transaction);
1908 journal_put_journal_head(jh);
1909 spin_unlock(&journal->j_list_lock);
1910 jbd_unlock_bh_state(bh);
1911 spin_unlock(&journal->j_state_lock);
1912 return ret;
1913 } else {
1914 /* The orphan record's transaction has
1915 * committed. We can cleanse this buffer */
1916 clear_buffer_jbddirty(bh);
1917 goto zap_buffer;
1918 }
1919 }
1920 } else if (transaction == journal->j_committing_transaction) {
Eric Sandeenf58a74d2006-10-28 10:38:27 -07001921 JBUFFER_TRACE(jh, "on committing transaction");
akpm@osdl.orgd13df842005-04-16 15:26:36 -07001922 if (jh->b_jlist == BJ_Locked) {
1923 /*
1924 * The buffer is on the committing transaction's locked
1925 * list. We have the buffer locked, so I/O has
1926 * completed. So we can nail the buffer now.
1927 */
1928 may_free = __dispose_buffer(jh, transaction);
1929 goto zap_buffer;
1930 }
1931 /*
1932 * If it is committing, we simply cannot touch it. We
Linus Torvalds1da177e2005-04-16 15:20:36 -07001933 * can remove it's next_transaction pointer from the
1934 * running transaction if that is set, but nothing
1935 * else. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001936 set_buffer_freed(bh);
1937 if (jh->b_next_transaction) {
1938 J_ASSERT(jh->b_next_transaction ==
1939 journal->j_running_transaction);
1940 jh->b_next_transaction = NULL;
1941 }
1942 journal_put_journal_head(jh);
1943 spin_unlock(&journal->j_list_lock);
1944 jbd_unlock_bh_state(bh);
1945 spin_unlock(&journal->j_state_lock);
1946 return 0;
1947 } else {
1948 /* Good, the buffer belongs to the running transaction.
1949 * We are writing our own transaction's data, not any
1950 * previous one's, so it is safe to throw it away
1951 * (remember that we expect the filesystem to have set
1952 * i_size already for this truncate so recovery will not
1953 * expose the disk blocks we are discarding here.) */
1954 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
Eric Sandeenf58a74d2006-10-28 10:38:27 -07001955 JBUFFER_TRACE(jh, "on running transaction");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001956 may_free = __dispose_buffer(jh, transaction);
1957 }
1958
1959zap_buffer:
1960 journal_put_journal_head(jh);
1961zap_buffer_no_jh:
1962 spin_unlock(&journal->j_list_lock);
1963 jbd_unlock_bh_state(bh);
1964 spin_unlock(&journal->j_state_lock);
1965zap_buffer_unlocked:
1966 clear_buffer_dirty(bh);
1967 J_ASSERT_BH(bh, !buffer_jbddirty(bh));
1968 clear_buffer_mapped(bh);
1969 clear_buffer_req(bh);
1970 clear_buffer_new(bh);
1971 bh->b_bdev = NULL;
1972 return may_free;
1973}
1974
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001975/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07001976 * void journal_invalidatepage() - invalidate a journal page
1977 * @journal: journal to use for flush
Linus Torvalds1da177e2005-04-16 15:20:36 -07001978 * @page: page to flush
1979 * @offset: length of page to invalidate.
1980 *
1981 * Reap page buffers containing data after offset in page.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001982 */
NeilBrown2ff28e22006-03-26 01:37:18 -08001983void journal_invalidatepage(journal_t *journal,
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001984 struct page *page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001985 unsigned long offset)
1986{
1987 struct buffer_head *head, *bh, *next;
1988 unsigned int curr_off = 0;
1989 int may_free = 1;
1990
1991 if (!PageLocked(page))
1992 BUG();
1993 if (!page_has_buffers(page))
NeilBrown2ff28e22006-03-26 01:37:18 -08001994 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001995
1996 /* We will potentially be playing with lists other than just the
1997 * data lists (especially for journaled data mode), so be
1998 * cautious in our locking. */
1999
2000 head = bh = page_buffers(page);
2001 do {
2002 unsigned int next_off = curr_off + bh->b_size;
2003 next = bh->b_this_page;
2004
Linus Torvalds1da177e2005-04-16 15:20:36 -07002005 if (offset <= curr_off) {
Dave Kleikampe9ad5622006-09-27 01:49:35 -07002006 /* This block is wholly outside the truncation point */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002007 lock_buffer(bh);
2008 may_free &= journal_unmap_buffer(journal, bh);
2009 unlock_buffer(bh);
2010 }
2011 curr_off = next_off;
2012 bh = next;
2013
2014 } while (bh != head);
2015
2016 if (!offset) {
NeilBrown2ff28e22006-03-26 01:37:18 -08002017 if (may_free && try_to_free_buffers(page))
2018 J_ASSERT(!page_has_buffers(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002019 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002020}
2021
Mingming Caoae6ddcc2006-09-27 01:49:27 -07002022/*
2023 * File a buffer on the given transaction list.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002024 */
2025void __journal_file_buffer(struct journal_head *jh,
2026 transaction_t *transaction, int jlist)
2027{
2028 struct journal_head **list = NULL;
2029 int was_dirty = 0;
2030 struct buffer_head *bh = jh2bh(jh);
2031
2032 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2033 assert_spin_locked(&transaction->t_journal->j_list_lock);
2034
2035 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
2036 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07002037 jh->b_transaction == NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002038
2039 if (jh->b_transaction && jh->b_jlist == jlist)
2040 return;
2041
Mingming Caoae6ddcc2006-09-27 01:49:27 -07002042 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07002043 jlist == BJ_Shadow || jlist == BJ_Forget) {
Jan Kara1e9fd532009-06-24 17:31:40 +02002044 /*
2045 * For metadata buffers, we track dirty bit in buffer_jbddirty
2046 * instead of buffer_dirty. We should not see a dirty bit set
2047 * here because we clear it in do_get_write_access but e.g.
2048 * tune2fs can modify the sb and set the dirty bit at any time
2049 * so we try to gracefully handle that.
2050 */
2051 if (buffer_dirty(bh))
2052 warn_dirty_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002053 if (test_clear_buffer_dirty(bh) ||
2054 test_clear_buffer_jbddirty(bh))
2055 was_dirty = 1;
2056 }
2057
2058 if (jh->b_transaction)
2059 __journal_temp_unlink_buffer(jh);
2060 jh->b_transaction = transaction;
2061
2062 switch (jlist) {
2063 case BJ_None:
2064 J_ASSERT_JH(jh, !jh->b_committed_data);
2065 J_ASSERT_JH(jh, !jh->b_frozen_data);
2066 return;
2067 case BJ_SyncData:
2068 list = &transaction->t_sync_datalist;
2069 break;
2070 case BJ_Metadata:
2071 transaction->t_nr_buffers++;
2072 list = &transaction->t_buffers;
2073 break;
2074 case BJ_Forget:
2075 list = &transaction->t_forget;
2076 break;
2077 case BJ_IO:
2078 list = &transaction->t_iobuf_list;
2079 break;
2080 case BJ_Shadow:
2081 list = &transaction->t_shadow_list;
2082 break;
2083 case BJ_LogCtl:
2084 list = &transaction->t_log_list;
2085 break;
2086 case BJ_Reserved:
2087 list = &transaction->t_reserved_list;
2088 break;
2089 case BJ_Locked:
2090 list = &transaction->t_locked_list;
2091 break;
2092 }
2093
2094 __blist_add_buffer(list, jh);
2095 jh->b_jlist = jlist;
2096
2097 if (was_dirty)
2098 set_buffer_jbddirty(bh);
2099}
2100
2101void journal_file_buffer(struct journal_head *jh,
2102 transaction_t *transaction, int jlist)
2103{
2104 jbd_lock_bh_state(jh2bh(jh));
2105 spin_lock(&transaction->t_journal->j_list_lock);
2106 __journal_file_buffer(jh, transaction, jlist);
2107 spin_unlock(&transaction->t_journal->j_list_lock);
2108 jbd_unlock_bh_state(jh2bh(jh));
2109}
2110
Mingming Caoae6ddcc2006-09-27 01:49:27 -07002111/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002112 * Remove a buffer from its current buffer list in preparation for
2113 * dropping it from its current transaction entirely. If the buffer has
2114 * already started to be used by a subsequent transaction, refile the
2115 * buffer on that transaction's metadata list.
2116 *
2117 * Called under journal->j_list_lock
2118 *
2119 * Called under jbd_lock_bh_state(jh2bh(jh))
2120 */
2121void __journal_refile_buffer(struct journal_head *jh)
2122{
2123 int was_dirty;
2124 struct buffer_head *bh = jh2bh(jh);
2125
2126 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2127 if (jh->b_transaction)
2128 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2129
2130 /* If the buffer is now unused, just drop it. */
2131 if (jh->b_next_transaction == NULL) {
2132 __journal_unfile_buffer(jh);
2133 return;
2134 }
2135
2136 /*
2137 * It has been modified by a later transaction: add it to the new
2138 * transaction's metadata list.
2139 */
2140
2141 was_dirty = test_clear_buffer_jbddirty(bh);
2142 __journal_temp_unlink_buffer(jh);
2143 jh->b_transaction = jh->b_next_transaction;
2144 jh->b_next_transaction = NULL;
Jan Kara9ada7342006-06-23 02:05:25 -07002145 __journal_file_buffer(jh, jh->b_transaction,
Josef Bacik5b9a4992008-04-28 02:16:12 -07002146 jh->b_modified ? BJ_Metadata : BJ_Reserved);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002147 J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2148
2149 if (was_dirty)
2150 set_buffer_jbddirty(bh);
2151}
2152
2153/*
2154 * For the unlocked version of this call, also make sure that any
2155 * hanging journal_head is cleaned up if necessary.
2156 *
2157 * __journal_refile_buffer is usually called as part of a single locked
2158 * operation on a buffer_head, in which the caller is probably going to
2159 * be hooking the journal_head onto other lists. In that case it is up
2160 * to the caller to remove the journal_head if necessary. For the
2161 * unlocked journal_refile_buffer call, the caller isn't going to be
2162 * doing anything else to the buffer so we need to do the cleanup
Mingming Caoae6ddcc2006-09-27 01:49:27 -07002163 * ourselves to avoid a jh leak.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002164 *
2165 * *** The journal_head may be freed by this call! ***
2166 */
2167void journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2168{
2169 struct buffer_head *bh = jh2bh(jh);
2170
2171 jbd_lock_bh_state(bh);
2172 spin_lock(&journal->j_list_lock);
2173
2174 __journal_refile_buffer(jh);
2175 jbd_unlock_bh_state(bh);
2176 journal_remove_journal_head(bh);
2177
2178 spin_unlock(&journal->j_list_lock);
2179 __brelse(bh);
2180}