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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. */
Arjan van de Ven44d306e2006-12-10 02:21:26 -080059 journal->j_commit_timer.expires = round_jiffies(transaction->t_expires);
Andrew Mortone3df1892006-03-25 03:06:53 -080060 add_timer(&journal->j_commit_timer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070061
62 J_ASSERT(journal->j_running_transaction == NULL);
63 journal->j_running_transaction = transaction;
64
65 return transaction;
66}
67
68/*
69 * Handle management.
70 *
71 * A handle_t is an object which represents a single atomic update to a
72 * filesystem, and which tracks all of the modifications which form part
73 * of that one update.
74 */
75
76/*
77 * start_this_handle: Given a handle, deal with any locking or stalling
78 * needed to make sure that there is enough journal space for the handle
79 * to begin. Attach the handle to a transaction and set up the
Mingming Caoae6ddcc2006-09-27 01:49:27 -070080 * transaction's buffer credits.
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 */
82
83static int start_this_handle(journal_t *journal, handle_t *handle)
84{
85 transaction_t *transaction;
86 int needed;
87 int nblocks = handle->h_buffer_credits;
88 transaction_t *new_transaction = NULL;
89 int ret = 0;
90
91 if (nblocks > journal->j_max_transaction_buffers) {
92 printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
93 current->comm, nblocks,
94 journal->j_max_transaction_buffers);
95 ret = -ENOSPC;
96 goto out;
97 }
98
99alloc_transaction:
100 if (!journal->j_running_transaction) {
Mingming Cao8c3478a2007-10-18 23:39:20 -0700101 new_transaction = kzalloc(sizeof(*new_transaction),
Mingming Caoa5005da2007-10-16 18:38:25 -0400102 GFP_NOFS|__GFP_NOFAIL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 if (!new_transaction) {
104 ret = -ENOMEM;
105 goto out;
106 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 }
108
109 jbd_debug(3, "New handle %p going live.\n", handle);
110
111repeat:
112
113 /*
114 * We need to hold j_state_lock until t_updates has been incremented,
115 * for proper journal barrier handling
116 */
117 spin_lock(&journal->j_state_lock);
118repeat_locked:
119 if (is_journal_aborted(journal) ||
120 (journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) {
121 spin_unlock(&journal->j_state_lock);
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700122 ret = -EROFS;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 goto out;
124 }
125
126 /* Wait on the journal's transaction barrier if necessary */
127 if (journal->j_barrier_count) {
128 spin_unlock(&journal->j_state_lock);
129 wait_event(journal->j_wait_transaction_locked,
130 journal->j_barrier_count == 0);
131 goto repeat;
132 }
133
134 if (!journal->j_running_transaction) {
135 if (!new_transaction) {
136 spin_unlock(&journal->j_state_lock);
137 goto alloc_transaction;
138 }
139 get_transaction(journal, new_transaction);
140 new_transaction = NULL;
141 }
142
143 transaction = journal->j_running_transaction;
144
145 /*
146 * If the current transaction is locked down for commit, wait for the
147 * lock to be released.
148 */
149 if (transaction->t_state == T_LOCKED) {
150 DEFINE_WAIT(wait);
151
152 prepare_to_wait(&journal->j_wait_transaction_locked,
153 &wait, TASK_UNINTERRUPTIBLE);
154 spin_unlock(&journal->j_state_lock);
155 schedule();
156 finish_wait(&journal->j_wait_transaction_locked, &wait);
157 goto repeat;
158 }
159
160 /*
161 * If there is not enough space left in the log to write all potential
162 * buffers requested by this operation, we need to stall pending a log
163 * checkpoint to free some more log space.
164 */
165 spin_lock(&transaction->t_handle_lock);
166 needed = transaction->t_outstanding_credits + nblocks;
167
168 if (needed > journal->j_max_transaction_buffers) {
169 /*
170 * If the current transaction is already too large, then start
171 * to commit it: we can then go back and attach this handle to
172 * a new transaction.
173 */
174 DEFINE_WAIT(wait);
175
176 jbd_debug(2, "Handle %p starting new commit...\n", handle);
177 spin_unlock(&transaction->t_handle_lock);
178 prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
179 TASK_UNINTERRUPTIBLE);
180 __log_start_commit(journal, transaction->t_tid);
181 spin_unlock(&journal->j_state_lock);
182 schedule();
183 finish_wait(&journal->j_wait_transaction_locked, &wait);
184 goto repeat;
185 }
186
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700187 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188 * The commit code assumes that it can get enough log space
189 * without forcing a checkpoint. This is *critical* for
190 * correctness: a checkpoint of a buffer which is also
191 * associated with a committing transaction creates a deadlock,
192 * so commit simply cannot force through checkpoints.
193 *
194 * We must therefore ensure the necessary space in the journal
195 * *before* starting to dirty potentially checkpointed buffers
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700196 * in the new transaction.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 *
198 * The worst part is, any transaction currently committing can
199 * reduce the free space arbitrarily. Be careful to account for
200 * those buffers when checkpointing.
201 */
202
203 /*
204 * @@@ AKPM: This seems rather over-defensive. We're giving commit
205 * a _lot_ of headroom: 1/4 of the journal plus the size of
206 * the committing transaction. Really, we only need to give it
207 * committing_transaction->t_outstanding_credits plus "enough" for
208 * the log control blocks.
209 * Also, this test is inconsitent with the matching one in
210 * journal_extend().
211 */
212 if (__log_space_left(journal) < jbd_space_needed(journal)) {
213 jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
214 spin_unlock(&transaction->t_handle_lock);
215 __log_wait_for_space(journal);
216 goto repeat_locked;
217 }
218
219 /* OK, account for the buffers that this operation expects to
220 * use and add the handle to the running transaction. */
221
222 handle->h_transaction = transaction;
223 transaction->t_outstanding_credits += nblocks;
224 transaction->t_updates++;
225 transaction->t_handle_count++;
226 jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
227 handle, nblocks, transaction->t_outstanding_credits,
228 __log_space_left(journal));
229 spin_unlock(&transaction->t_handle_lock);
230 spin_unlock(&journal->j_state_lock);
231out:
Andrew Morton304c4c82006-06-23 02:05:31 -0700232 if (unlikely(new_transaction)) /* It's usually NULL */
233 kfree(new_transaction);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 return ret;
235}
236
Peter Zijlstra34a3d1e2007-10-11 22:11:12 +0200237static struct lock_class_key jbd_handle_key;
238
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239/* Allocate a new handle. This should probably be in a slab... */
240static handle_t *new_handle(int nblocks)
241{
242 handle_t *handle = jbd_alloc_handle(GFP_NOFS);
243 if (!handle)
244 return NULL;
245 memset(handle, 0, sizeof(*handle));
246 handle->h_buffer_credits = nblocks;
247 handle->h_ref = 1;
248
Peter Zijlstra34a3d1e2007-10-11 22:11:12 +0200249 lockdep_init_map(&handle->h_lockdep_map, "jbd_handle", &jbd_handle_key, 0);
250
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 return handle;
252}
253
254/**
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700255 * handle_t *journal_start() - Obtain a new handle.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 * @journal: Journal to start transaction on.
257 * @nblocks: number of block buffer we might modify
258 *
259 * We make sure that the transaction can guarantee at least nblocks of
260 * modified buffers in the log. We block until the log can guarantee
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700261 * that much space.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 *
263 * This function is visible to journal users (like ext3fs), so is not
264 * called with the journal already locked.
265 *
266 * Return a pointer to a newly allocated handle, or NULL on failure
267 */
268handle_t *journal_start(journal_t *journal, int nblocks)
269{
270 handle_t *handle = journal_current_handle();
271 int err;
272
273 if (!journal)
274 return ERR_PTR(-EROFS);
275
276 if (handle) {
277 J_ASSERT(handle->h_transaction->t_journal == journal);
278 handle->h_ref++;
279 return handle;
280 }
281
282 handle = new_handle(nblocks);
283 if (!handle)
284 return ERR_PTR(-ENOMEM);
285
286 current->journal_info = handle;
287
288 err = start_this_handle(journal, handle);
289 if (err < 0) {
290 jbd_free_handle(handle);
291 current->journal_info = NULL;
292 handle = ERR_PTR(err);
Jonas Bonnf63dcda2008-01-17 15:21:13 -0800293 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294 }
Peter Zijlstra34a3d1e2007-10-11 22:11:12 +0200295
Ingo Molnar3295f0e2008-08-11 10:30:30 +0200296 lock_map_acquire(&handle->h_lockdep_map);
Peter Zijlstra34a3d1e2007-10-11 22:11:12 +0200297
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
419 handle->h_buffer_credits = nblocks;
420 ret = start_this_handle(journal, handle);
421 return ret;
422}
423
424
425/**
426 * void journal_lock_updates () - establish a transaction barrier.
427 * @journal: Journal to establish a barrier on.
428 *
429 * This locks out any further updates from being started, and blocks
430 * until all existing updates have completed, returning only once the
431 * journal is in a quiescent state with no updates running.
432 *
433 * The journal lock should not be held on entry.
434 */
435void journal_lock_updates(journal_t *journal)
436{
437 DEFINE_WAIT(wait);
438
439 spin_lock(&journal->j_state_lock);
440 ++journal->j_barrier_count;
441
442 /* Wait until there are no running updates */
443 while (1) {
444 transaction_t *transaction = journal->j_running_transaction;
445
446 if (!transaction)
447 break;
448
449 spin_lock(&transaction->t_handle_lock);
450 if (!transaction->t_updates) {
451 spin_unlock(&transaction->t_handle_lock);
452 break;
453 }
454 prepare_to_wait(&journal->j_wait_updates, &wait,
455 TASK_UNINTERRUPTIBLE);
456 spin_unlock(&transaction->t_handle_lock);
457 spin_unlock(&journal->j_state_lock);
458 schedule();
459 finish_wait(&journal->j_wait_updates, &wait);
460 spin_lock(&journal->j_state_lock);
461 }
462 spin_unlock(&journal->j_state_lock);
463
464 /*
465 * We have now established a barrier against other normal updates, but
466 * we also need to barrier against other journal_lock_updates() calls
467 * to make sure that we serialise special journal-locked operations
468 * too.
469 */
Arjan van de Ven2c68ee72006-03-23 03:00:35 -0800470 mutex_lock(&journal->j_barrier);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471}
472
473/**
474 * void journal_unlock_updates (journal_t* journal) - release barrier
475 * @journal: Journal to release the barrier on.
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700476 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 * Release a transaction barrier obtained with journal_lock_updates().
478 *
479 * Should be called without the journal lock held.
480 */
481void journal_unlock_updates (journal_t *journal)
482{
483 J_ASSERT(journal->j_barrier_count != 0);
484
Arjan van de Ven2c68ee72006-03-23 03:00:35 -0800485 mutex_unlock(&journal->j_barrier);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486 spin_lock(&journal->j_state_lock);
487 --journal->j_barrier_count;
488 spin_unlock(&journal->j_state_lock);
489 wake_up(&journal->j_wait_transaction_locked);
490}
491
Jan Kara1e9fd532009-06-24 17:31:40 +0200492static void warn_dirty_buffer(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493{
Jan Kara1e9fd532009-06-24 17:31:40 +0200494 char b[BDEVNAME_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495
Jan Kara1e9fd532009-06-24 17:31:40 +0200496 printk(KERN_WARNING
497 "JBD: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). "
498 "There's a risk of filesystem corruption in case of system "
499 "crash.\n",
500 bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501}
502
503/*
504 * If the buffer is already part of the current transaction, then there
505 * is nothing we need to do. If it is already part of a prior
506 * transaction which we are still committing to disk, then we need to
507 * make sure that we do not overwrite the old copy: we do copy-out to
508 * preserve the copy going to disk. We also account the buffer against
509 * the handle's metadata buffer credits (unless the buffer is already
510 * part of the transaction, that is).
511 *
512 */
513static int
514do_get_write_access(handle_t *handle, struct journal_head *jh,
515 int force_copy)
516{
517 struct buffer_head *bh;
518 transaction_t *transaction;
519 journal_t *journal;
520 int error;
521 char *frozen_buffer = NULL;
522 int need_copy = 0;
523
524 if (is_handle_aborted(handle))
525 return -EROFS;
526
527 transaction = handle->h_transaction;
528 journal = transaction->t_journal;
529
530 jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy);
531
532 JBUFFER_TRACE(jh, "entry");
533repeat:
534 bh = jh2bh(jh);
535
536 /* @@@ Need to check for errors here at some point. */
537
538 lock_buffer(bh);
539 jbd_lock_bh_state(bh);
540
541 /* We now hold the buffer lock so it is safe to query the buffer
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700542 * state. Is the buffer dirty?
543 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544 * If so, there are two possibilities. The buffer may be
545 * non-journaled, and undergoing a quite legitimate writeback.
546 * Otherwise, it is journaled, and we don't expect dirty buffers
547 * in that state (the buffers should be marked JBD_Dirty
548 * instead.) So either the IO is being done under our own
549 * control and this is a bug, or it's a third party IO such as
550 * dump(8) (which may leave the buffer scheduled for read ---
551 * ie. locked but not dirty) or tune2fs (which may actually have
552 * the buffer dirtied, ugh.) */
553
554 if (buffer_dirty(bh)) {
555 /*
556 * First question: is this buffer already part of the current
557 * transaction or the existing committing transaction?
558 */
559 if (jh->b_transaction) {
560 J_ASSERT_JH(jh,
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700561 jh->b_transaction == transaction ||
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 jh->b_transaction ==
563 journal->j_committing_transaction);
564 if (jh->b_next_transaction)
565 J_ASSERT_JH(jh, jh->b_next_transaction ==
566 transaction);
Jan Kara1e9fd532009-06-24 17:31:40 +0200567 warn_dirty_buffer(bh);
Jan Kara4407c2b2005-09-06 15:19:17 -0700568 }
569 /*
570 * In any case we need to clean the dirty flag and we must
571 * do it under the buffer lock to be sure we don't race
572 * with running write-out.
573 */
Jan Kara1e9fd532009-06-24 17:31:40 +0200574 JBUFFER_TRACE(jh, "Journalling dirty buffer");
575 clear_buffer_dirty(bh);
576 set_buffer_jbddirty(bh);
Dave Kleikampe9ad5622006-09-27 01:49:35 -0700577 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578
579 unlock_buffer(bh);
580
581 error = -EROFS;
582 if (is_handle_aborted(handle)) {
583 jbd_unlock_bh_state(bh);
584 goto out;
585 }
586 error = 0;
587
588 /*
589 * The buffer is already part of this transaction if b_transaction or
590 * b_next_transaction points to it
591 */
592 if (jh->b_transaction == transaction ||
593 jh->b_next_transaction == transaction)
594 goto done;
595
596 /*
Josef Bacik5bc833f2008-04-28 02:16:10 -0700597 * this is the first time this transaction is touching this buffer,
598 * reset the modified flag
599 */
600 jh->b_modified = 0;
601
602 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603 * 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 =
Mingming Caoc089d492007-10-16 18:38:25 -0400670 jbd_alloc(jh2bh(jh)->b_size,
Badari Pulavartyea817392006-08-27 01:23:52 -0700671 GFP_NOFS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672 if (!frozen_buffer) {
673 printk(KERN_EMERG
674 "%s: OOM for frozen_buffer\n",
Harvey Harrison08fc99b2008-04-28 02:16:16 -0700675 __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676 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 */
Mingming Caoc089d492007-10-16 18:38:25 -0400730 jbd_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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 *
741 * Returns an error code or 0 on success.
742 *
743 * In full data journalling mode the buffer may be of type BJ_AsyncData,
744 * because we're write()ing a buffer which is also part of a shared mapping.
745 */
746
747int journal_get_write_access(handle_t *handle, struct buffer_head *bh)
748{
749 struct journal_head *jh = journal_add_journal_head(bh);
750 int rc;
751
752 /* We do not want to get caught playing with fields which the
753 * log thread also manipulates. Make sure that the buffer
754 * completes any outstanding IO before proceeding. */
755 rc = do_get_write_access(handle, jh, 0);
756 journal_put_journal_head(jh);
757 return rc;
758}
759
760
761/*
762 * When the user wants to journal a newly created buffer_head
763 * (ie. getblk() returned a new buffer and we are going to populate it
764 * manually rather than reading off disk), then we need to keep the
765 * buffer_head locked until it has been completely filled with new
766 * data. In this case, we should be able to make the assertion that
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700767 * the bh is not already part of an existing transaction.
768 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769 * The buffer should already be locked by the caller by this point.
770 * There is no lock ranking violation: it was a newly created,
771 * unlocked buffer beforehand. */
772
773/**
774 * int journal_get_create_access () - notify intent to use newly created bh
775 * @handle: transaction to new buffer to
776 * @bh: new buffer.
777 *
778 * Call this if you create a new bh.
779 */
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700780int journal_get_create_access(handle_t *handle, struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781{
782 transaction_t *transaction = handle->h_transaction;
783 journal_t *journal = transaction->t_journal;
784 struct journal_head *jh = journal_add_journal_head(bh);
785 int err;
786
787 jbd_debug(5, "journal_head %p\n", jh);
788 err = -EROFS;
789 if (is_handle_aborted(handle))
790 goto out;
791 err = 0;
792
793 JBUFFER_TRACE(jh, "entry");
794 /*
795 * The buffer may already belong to this transaction due to pre-zeroing
796 * in the filesystem's new_block code. It may also be on the previous,
797 * committing transaction's lists, but it HAS to be in Forget state in
798 * that case: the transaction must have deleted the buffer for it to be
799 * reused here.
800 */
801 jbd_lock_bh_state(bh);
802 spin_lock(&journal->j_list_lock);
803 J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
804 jh->b_transaction == NULL ||
805 (jh->b_transaction == journal->j_committing_transaction &&
806 jh->b_jlist == BJ_Forget)));
807
808 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
809 J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
810
811 if (jh->b_transaction == NULL) {
Jan Kara1e9fd532009-06-24 17:31:40 +0200812 /*
813 * Previous journal_forget() could have left the buffer
814 * with jbddirty bit set because it was being committed. When
815 * the commit finished, we've filed the buffer for
816 * checkpointing and marked it dirty. Now we are reallocating
817 * the buffer so the transaction freeing it must have
818 * committed and so it's safe to clear the dirty bit.
819 */
820 clear_buffer_dirty(jh2bh(jh));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821 jh->b_transaction = transaction;
Josef Bacik5bc833f2008-04-28 02:16:10 -0700822
823 /* first access by this transaction */
824 jh->b_modified = 0;
825
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826 JBUFFER_TRACE(jh, "file as BJ_Reserved");
827 __journal_file_buffer(jh, transaction, BJ_Reserved);
828 } else if (jh->b_transaction == journal->j_committing_transaction) {
Josef Bacik5bc833f2008-04-28 02:16:10 -0700829 /* first access by this transaction */
830 jh->b_modified = 0;
831
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 JBUFFER_TRACE(jh, "set next transaction");
833 jh->b_next_transaction = transaction;
834 }
835 spin_unlock(&journal->j_list_lock);
836 jbd_unlock_bh_state(bh);
837
838 /*
839 * akpm: I added this. ext3_alloc_branch can pick up new indirect
840 * blocks which contain freed but then revoked metadata. We need
841 * to cancel the revoke in case we end up freeing it yet again
842 * and the reallocating as data - this would cause a second revoke,
843 * which hits an assertion error.
844 */
845 JBUFFER_TRACE(jh, "cancelling revoke");
846 journal_cancel_revoke(handle, jh);
847 journal_put_journal_head(jh);
848out:
849 return err;
850}
851
852/**
Randy Dunlap78a4a502008-02-29 22:02:31 -0800853 * int journal_get_undo_access() - Notify intent to modify metadata with non-rewindable consequences
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854 * @handle: transaction
855 * @bh: buffer to undo
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856 *
857 * Sometimes there is a need to distinguish between metadata which has
858 * been committed to disk and that which has not. The ext3fs code uses
859 * this for freeing and allocating space, we have to make sure that we
860 * do not reuse freed space until the deallocation has been committed,
861 * since if we overwrote that space we would make the delete
862 * un-rewindable in case of a crash.
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700863 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864 * To deal with that, journal_get_undo_access requests write access to a
865 * buffer for parts of non-rewindable operations such as delete
866 * operations on the bitmaps. The journaling code must keep a copy of
867 * the buffer's contents prior to the undo_access call until such time
868 * as we know that the buffer has definitely been committed to disk.
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700869 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700870 * We never need to know which transaction the committed data is part
871 * of, buffers touched here are guaranteed to be dirtied later and so
872 * will be committed to a new transaction in due course, at which point
873 * we can discard the old committed data pointer.
874 *
875 * Returns error number or 0 on success.
876 */
877int journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
878{
879 int err;
880 struct journal_head *jh = journal_add_journal_head(bh);
881 char *committed_data = NULL;
882
883 JBUFFER_TRACE(jh, "entry");
884
885 /*
886 * Do this first --- it can drop the journal lock, so we want to
887 * make sure that obtaining the committed_data is done
888 * atomically wrt. completion of any outstanding commits.
889 */
890 err = do_get_write_access(handle, jh, 1);
891 if (err)
892 goto out;
893
894repeat:
895 if (!jh->b_committed_data) {
Mingming Caoc089d492007-10-16 18:38:25 -0400896 committed_data = jbd_alloc(jh2bh(jh)->b_size, GFP_NOFS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700897 if (!committed_data) {
898 printk(KERN_EMERG "%s: No memory for committed data\n",
Harvey Harrison08fc99b2008-04-28 02:16:16 -0700899 __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 err = -ENOMEM;
901 goto out;
902 }
903 }
904
905 jbd_lock_bh_state(bh);
906 if (!jh->b_committed_data) {
907 /* Copy out the current buffer contents into the
908 * preserved, committed copy. */
909 JBUFFER_TRACE(jh, "generate b_committed data");
910 if (!committed_data) {
911 jbd_unlock_bh_state(bh);
912 goto repeat;
913 }
914
915 jh->b_committed_data = committed_data;
916 committed_data = NULL;
917 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
918 }
919 jbd_unlock_bh_state(bh);
920out:
921 journal_put_journal_head(jh);
Andrew Morton304c4c82006-06-23 02:05:31 -0700922 if (unlikely(committed_data))
Mingming Caoc089d492007-10-16 18:38:25 -0400923 jbd_free(committed_data, bh->b_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924 return err;
925}
926
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700927/**
Randy Dunlap78a4a502008-02-29 22:02:31 -0800928 * int journal_dirty_data() - mark a buffer as containing dirty data to be flushed
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929 * @handle: transaction
930 * @bh: bufferhead to mark
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700931 *
Randy Dunlap78a4a502008-02-29 22:02:31 -0800932 * Description:
933 * Mark a buffer as containing dirty data which needs to be flushed before
934 * we can commit the current transaction.
935 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700936 * The buffer is placed on the transaction's data list and is marked as
937 * belonging to the transaction.
938 *
939 * Returns error number or 0 on success.
940 *
941 * journal_dirty_data() can be called via page_launder->ext3_writepage
942 * by kswapd.
943 */
944int journal_dirty_data(handle_t *handle, struct buffer_head *bh)
945{
946 journal_t *journal = handle->h_transaction->t_journal;
947 int need_brelse = 0;
948 struct journal_head *jh;
Hidehiro Kawai960a22a2008-10-18 20:27:58 -0700949 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950
951 if (is_handle_aborted(handle))
Hidehiro Kawai960a22a2008-10-18 20:27:58 -0700952 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700953
954 jh = journal_add_journal_head(bh);
955 JBUFFER_TRACE(jh, "entry");
956
957 /*
958 * The buffer could *already* be dirty. Writeout can start
959 * at any time.
960 */
961 jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
962
963 /*
964 * What if the buffer is already part of a running transaction?
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700965 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700966 * There are two cases:
967 * 1) It is part of the current running transaction. Refile it,
968 * just in case we have allocated it as metadata, deallocated
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700969 * it, then reallocated it as data.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700970 * 2) It is part of the previous, still-committing transaction.
971 * If all we want to do is to guarantee that the buffer will be
972 * written to disk before this new transaction commits, then
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700973 * being sure that the *previous* transaction has this same
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974 * property is sufficient for us! Just leave it on its old
975 * transaction.
976 *
977 * In case (2), the buffer must not already exist as metadata
978 * --- that would violate write ordering (a transaction is free
979 * to write its data at any point, even before the previous
980 * committing transaction has committed). The caller must
981 * never, ever allow this to happen: there's nothing we can do
982 * about it in this layer.
983 */
984 jbd_lock_bh_state(bh);
985 spin_lock(&journal->j_list_lock);
Eric Sandeenf58a74d2006-10-28 10:38:27 -0700986
987 /* Now that we have bh_state locked, are we really still mapped? */
988 if (!buffer_mapped(bh)) {
989 JBUFFER_TRACE(jh, "unmapped buffer, bailing out");
990 goto no_journal;
991 }
992
Linus Torvalds1da177e2005-04-16 15:20:36 -0700993 if (jh->b_transaction) {
994 JBUFFER_TRACE(jh, "has transaction");
995 if (jh->b_transaction != handle->h_transaction) {
996 JBUFFER_TRACE(jh, "belongs to older transaction");
997 J_ASSERT_JH(jh, jh->b_transaction ==
998 journal->j_committing_transaction);
999
1000 /* @@@ IS THIS TRUE ? */
1001 /*
1002 * Not any more. Scenario: someone does a write()
1003 * in data=journal mode. The buffer's transaction has
1004 * moved into commit. Then someone does another
1005 * write() to the file. We do the frozen data copyout
1006 * and set b_next_transaction to point to j_running_t.
1007 * And while we're in that state, someone does a
1008 * writepage() in an attempt to pageout the same area
1009 * of the file via a shared mapping. At present that
1010 * calls journal_dirty_data(), and we get right here.
1011 * It may be too late to journal the data. Simply
1012 * falling through to the next test will suffice: the
1013 * data will be dirty and wil be checkpointed. The
1014 * ordering comments in the next comment block still
1015 * apply.
1016 */
1017 //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1018
1019 /*
1020 * If we're journalling data, and this buffer was
1021 * subject to a write(), it could be metadata, forget
1022 * or shadow against the committing transaction. Now,
1023 * someone has dirtied the same darn page via a mapping
1024 * and it is being writepage()'d.
1025 * We *could* just steal the page from commit, with some
1026 * fancy locking there. Instead, we just skip it -
1027 * don't tie the page's buffers to the new transaction
1028 * at all.
1029 * Implication: if we crash before the writepage() data
1030 * is written into the filesystem, recovery will replay
1031 * the write() data.
1032 */
1033 if (jh->b_jlist != BJ_None &&
1034 jh->b_jlist != BJ_SyncData &&
1035 jh->b_jlist != BJ_Locked) {
1036 JBUFFER_TRACE(jh, "Not stealing");
1037 goto no_journal;
1038 }
1039
1040 /*
1041 * This buffer may be undergoing writeout in commit. We
1042 * can't return from here and let the caller dirty it
1043 * again because that can cause the write-out loop in
1044 * commit to never terminate.
1045 */
1046 if (buffer_dirty(bh)) {
1047 get_bh(bh);
1048 spin_unlock(&journal->j_list_lock);
1049 jbd_unlock_bh_state(bh);
1050 need_brelse = 1;
1051 sync_dirty_buffer(bh);
1052 jbd_lock_bh_state(bh);
1053 spin_lock(&journal->j_list_lock);
Eric Sandeenf58a74d2006-10-28 10:38:27 -07001054 /* Since we dropped the lock... */
1055 if (!buffer_mapped(bh)) {
1056 JBUFFER_TRACE(jh, "buffer got unmapped");
1057 goto no_journal;
1058 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001059 /* The buffer may become locked again at any
1060 time if it is redirtied */
1061 }
1062
Hidehiro Kawai960a22a2008-10-18 20:27:58 -07001063 /*
1064 * We cannot remove the buffer with io error from the
1065 * committing transaction, because otherwise it would
1066 * miss the error and the commit would not abort.
1067 */
1068 if (unlikely(!buffer_uptodate(bh))) {
1069 ret = -EIO;
1070 goto no_journal;
1071 }
1072
Linus Torvalds1da177e2005-04-16 15:20:36 -07001073 if (jh->b_transaction != NULL) {
1074 JBUFFER_TRACE(jh, "unfile from commit");
1075 __journal_temp_unlink_buffer(jh);
1076 /* It still points to the committing
1077 * transaction; move it to this one so
1078 * that the refile assert checks are
1079 * happy. */
1080 jh->b_transaction = handle->h_transaction;
1081 }
1082 /* The buffer will be refiled below */
1083
1084 }
1085 /*
1086 * Special case --- the buffer might actually have been
1087 * allocated and then immediately deallocated in the previous,
1088 * committing transaction, so might still be left on that
1089 * transaction's metadata lists.
1090 */
1091 if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
1092 JBUFFER_TRACE(jh, "not on correct data list: unfile");
1093 J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
1094 __journal_temp_unlink_buffer(jh);
1095 jh->b_transaction = handle->h_transaction;
1096 JBUFFER_TRACE(jh, "file as data");
1097 __journal_file_buffer(jh, handle->h_transaction,
1098 BJ_SyncData);
1099 }
1100 } else {
1101 JBUFFER_TRACE(jh, "not on a transaction");
1102 __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
1103 }
1104no_journal:
1105 spin_unlock(&journal->j_list_lock);
1106 jbd_unlock_bh_state(bh);
1107 if (need_brelse) {
1108 BUFFER_TRACE(bh, "brelse");
1109 __brelse(bh);
1110 }
1111 JBUFFER_TRACE(jh, "exit");
1112 journal_put_journal_head(jh);
Hidehiro Kawai960a22a2008-10-18 20:27:58 -07001113 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114}
1115
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001116/**
Randy Dunlap78a4a502008-02-29 22:02:31 -08001117 * int journal_dirty_metadata() - mark a buffer as containing dirty metadata
Linus Torvalds1da177e2005-04-16 15:20:36 -07001118 * @handle: transaction to add buffer to.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001119 * @bh: buffer to mark
1120 *
Randy Dunlap78a4a502008-02-29 22:02:31 -08001121 * Mark dirty metadata which needs to be journaled as part of the current
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122 * transaction.
1123 *
1124 * The buffer is placed on the transaction's metadata list and is marked
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001125 * as belonging to the transaction.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126 *
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001127 * Returns error number or 0 on success.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001128 *
1129 * Special care needs to be taken if the buffer already belongs to the
1130 * current committing transaction (in which case we should have frozen
1131 * data present for that commit). In that case, we don't relink the
1132 * buffer: that only gets done when the old transaction finally
1133 * completes its commit.
1134 */
1135int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1136{
1137 transaction_t *transaction = handle->h_transaction;
1138 journal_t *journal = transaction->t_journal;
1139 struct journal_head *jh = bh2jh(bh);
1140
1141 jbd_debug(5, "journal_head %p\n", jh);
1142 JBUFFER_TRACE(jh, "entry");
1143 if (is_handle_aborted(handle))
1144 goto out;
1145
1146 jbd_lock_bh_state(bh);
1147
1148 if (jh->b_modified == 0) {
1149 /*
1150 * This buffer's got modified and becoming part
1151 * of the transaction. This needs to be done
1152 * once a transaction -bzzz
1153 */
1154 jh->b_modified = 1;
1155 J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
1156 handle->h_buffer_credits--;
1157 }
1158
1159 /*
1160 * fastpath, to avoid expensive locking. If this buffer is already
1161 * on the running transaction's metadata list there is nothing to do.
1162 * Nobody can take it off again because there is a handle open.
1163 * I _think_ we're OK here with SMP barriers - a mistaken decision will
1164 * result in this test being false, so we go in and take the locks.
1165 */
1166 if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1167 JBUFFER_TRACE(jh, "fastpath");
1168 J_ASSERT_JH(jh, jh->b_transaction ==
1169 journal->j_running_transaction);
1170 goto out_unlock_bh;
1171 }
1172
1173 set_buffer_jbddirty(bh);
1174
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001175 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001176 * Metadata already on the current transaction list doesn't
1177 * need to be filed. Metadata on another transaction's list must
1178 * be committing, and will be refiled once the commit completes:
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001179 * leave it alone for now.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180 */
1181 if (jh->b_transaction != transaction) {
1182 JBUFFER_TRACE(jh, "already on other transaction");
1183 J_ASSERT_JH(jh, jh->b_transaction ==
1184 journal->j_committing_transaction);
1185 J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
1186 /* And this case is illegal: we can't reuse another
1187 * transaction's data buffer, ever. */
1188 goto out_unlock_bh;
1189 }
1190
1191 /* That test should have eliminated the following case: */
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001192 J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193
1194 JBUFFER_TRACE(jh, "file as BJ_Metadata");
1195 spin_lock(&journal->j_list_lock);
1196 __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1197 spin_unlock(&journal->j_list_lock);
1198out_unlock_bh:
1199 jbd_unlock_bh_state(bh);
1200out:
1201 JBUFFER_TRACE(jh, "exit");
1202 return 0;
1203}
1204
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001205/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206 * journal_release_buffer: undo a get_write_access without any buffer
1207 * updates, if the update decided in the end that it didn't need access.
1208 *
1209 */
1210void
1211journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1212{
1213 BUFFER_TRACE(bh, "entry");
1214}
1215
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001216/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001217 * void journal_forget() - bforget() for potentially-journaled buffers.
1218 * @handle: transaction handle
1219 * @bh: bh to 'forget'
1220 *
1221 * We can only do the bforget if there are no commits pending against the
1222 * buffer. If the buffer is dirty in the current running transaction we
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001223 * can safely unlink it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001224 *
1225 * bh may not be a journalled buffer at all - it may be a non-JBD
1226 * buffer which came off the hashtable. Check for this.
1227 *
1228 * Decrements bh->b_count by one.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001229 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001230 * Allow this call even if the handle has aborted --- it may be part of
1231 * the caller's cleanup after an abort.
1232 */
1233int journal_forget (handle_t *handle, struct buffer_head *bh)
1234{
1235 transaction_t *transaction = handle->h_transaction;
1236 journal_t *journal = transaction->t_journal;
1237 struct journal_head *jh;
1238 int drop_reserve = 0;
1239 int err = 0;
Josef Bacik5b9a4992008-04-28 02:16:12 -07001240 int was_modified = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001241
1242 BUFFER_TRACE(bh, "entry");
1243
1244 jbd_lock_bh_state(bh);
1245 spin_lock(&journal->j_list_lock);
1246
1247 if (!buffer_jbd(bh))
1248 goto not_jbd;
1249 jh = bh2jh(bh);
1250
1251 /* Critical error: attempting to delete a bitmap buffer, maybe?
1252 * Don't do any jbd operations, and return an error. */
1253 if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1254 "inconsistent data on disk")) {
1255 err = -EIO;
1256 goto not_jbd;
1257 }
1258
Josef Bacik5b9a4992008-04-28 02:16:12 -07001259 /* keep track of wether or not this transaction modified us */
1260 was_modified = jh->b_modified;
1261
Linus Torvalds1da177e2005-04-16 15:20:36 -07001262 /*
1263 * The buffer's going from the transaction, we must drop
1264 * all references -bzzz
1265 */
1266 jh->b_modified = 0;
1267
1268 if (jh->b_transaction == handle->h_transaction) {
1269 J_ASSERT_JH(jh, !jh->b_frozen_data);
1270
1271 /* If we are forgetting a buffer which is already part
1272 * of this transaction, then we can just drop it from
1273 * the transaction immediately. */
1274 clear_buffer_dirty(bh);
1275 clear_buffer_jbddirty(bh);
1276
1277 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1278
Josef Bacik5b9a4992008-04-28 02:16:12 -07001279 /*
1280 * we only want to drop a reference if this transaction
1281 * modified the buffer
1282 */
1283 if (was_modified)
1284 drop_reserve = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001286 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001287 * We are no longer going to journal this buffer.
1288 * However, the commit of this transaction is still
1289 * important to the buffer: the delete that we are now
1290 * processing might obsolete an old log entry, so by
1291 * committing, we can satisfy the buffer's checkpoint.
1292 *
1293 * So, if we have a checkpoint on the buffer, we should
1294 * now refile the buffer on our BJ_Forget list so that
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001295 * we know to remove the checkpoint after we commit.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296 */
1297
1298 if (jh->b_cp_transaction) {
1299 __journal_temp_unlink_buffer(jh);
1300 __journal_file_buffer(jh, transaction, BJ_Forget);
1301 } else {
1302 __journal_unfile_buffer(jh);
1303 journal_remove_journal_head(bh);
1304 __brelse(bh);
1305 if (!buffer_jbd(bh)) {
1306 spin_unlock(&journal->j_list_lock);
1307 jbd_unlock_bh_state(bh);
1308 __bforget(bh);
1309 goto drop;
1310 }
1311 }
1312 } else if (jh->b_transaction) {
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001313 J_ASSERT_JH(jh, (jh->b_transaction ==
Linus Torvalds1da177e2005-04-16 15:20:36 -07001314 journal->j_committing_transaction));
1315 /* However, if the buffer is still owned by a prior
1316 * (committing) transaction, we can't drop it yet... */
1317 JBUFFER_TRACE(jh, "belongs to older transaction");
1318 /* ... but we CAN drop it from the new transaction if we
1319 * have also modified it since the original commit. */
1320
1321 if (jh->b_next_transaction) {
1322 J_ASSERT(jh->b_next_transaction == transaction);
1323 jh->b_next_transaction = NULL;
Josef Bacik5b9a4992008-04-28 02:16:12 -07001324
1325 /*
1326 * only drop a reference if this transaction modified
1327 * the buffer
1328 */
1329 if (was_modified)
1330 drop_reserve = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001331 }
1332 }
1333
1334not_jbd:
1335 spin_unlock(&journal->j_list_lock);
1336 jbd_unlock_bh_state(bh);
1337 __brelse(bh);
1338drop:
1339 if (drop_reserve) {
1340 /* no need to reserve log space for this block -bzzz */
1341 handle->h_buffer_credits++;
1342 }
1343 return err;
1344}
1345
1346/**
1347 * int journal_stop() - complete a transaction
1348 * @handle: tranaction to complete.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001349 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001350 * All done for a particular handle.
1351 *
1352 * There is not much action needed here. We just return any remaining
1353 * buffer credits to the transaction and remove the handle. The only
1354 * complication is that we need to start a commit operation if the
1355 * filesystem is marked for synchronous update.
1356 *
1357 * journal_stop itself will not usually return an error, but it may
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001358 * do so in unusual circumstances. In particular, expect it to
Linus Torvalds1da177e2005-04-16 15:20:36 -07001359 * return -EIO if a journal_abort has been executed since the
1360 * transaction began.
1361 */
1362int journal_stop(handle_t *handle)
1363{
1364 transaction_t *transaction = handle->h_transaction;
1365 journal_t *journal = transaction->t_journal;
Josef Bacikf420d4d2009-01-07 18:07:24 -08001366 int err;
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001367 pid_t pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369 J_ASSERT(journal_current_handle() == handle);
1370
1371 if (is_handle_aborted(handle))
1372 err = -EIO;
OGAWA Hirofumi3e2a5322006-10-19 23:29:11 -07001373 else {
1374 J_ASSERT(transaction->t_updates > 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001375 err = 0;
OGAWA Hirofumi3e2a5322006-10-19 23:29:11 -07001376 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377
1378 if (--handle->h_ref > 0) {
1379 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1380 handle->h_ref);
1381 return err;
1382 }
1383
1384 jbd_debug(4, "Handle %p going down\n", handle);
1385
1386 /*
1387 * Implement synchronous transaction batching. If the handle
1388 * was synchronous, don't force a commit immediately. Let's
1389 * yield and let another thread piggyback onto this transaction.
1390 * Keep doing that while new threads continue to arrive.
1391 * It doesn't cost much - we're about to run a commit and sleep
1392 * on IO anyway. Speeds up many-threaded, many-dir operations
1393 * by 30x or more...
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001394 *
Josef Bacikf420d4d2009-01-07 18:07:24 -08001395 * We try and optimize the sleep time against what the underlying disk
1396 * can do, instead of having a static sleep time. This is usefull for
1397 * the case where our storage is so fast that it is more optimal to go
1398 * ahead and force a flush and wait for the transaction to be committed
1399 * than it is to wait for an arbitrary amount of time for new writers to
1400 * join the transaction. We acheive this by measuring how long it takes
1401 * to commit a transaction, and compare it with how long this
1402 * transaction has been running, and if run time < commit time then we
1403 * sleep for the delta and commit. This greatly helps super fast disks
1404 * that would see slowdowns as more threads started doing fsyncs.
1405 *
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001406 * But don't do this if this process was the most recent one to
1407 * perform a synchronous write. We do this to detect the case where a
1408 * single process is doing a stream of sync writes. No point in waiting
1409 * for joiners in that case.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410 */
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001411 pid = current->pid;
1412 if (handle->h_sync && journal->j_last_sync_writer != pid) {
Josef Bacikf420d4d2009-01-07 18:07:24 -08001413 u64 commit_time, trans_time;
1414
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001415 journal->j_last_sync_writer = pid;
Josef Bacikf420d4d2009-01-07 18:07:24 -08001416
1417 spin_lock(&journal->j_state_lock);
1418 commit_time = journal->j_average_commit_time;
1419 spin_unlock(&journal->j_state_lock);
1420
1421 trans_time = ktime_to_ns(ktime_sub(ktime_get(),
1422 transaction->t_start_time));
1423
1424 commit_time = min_t(u64, commit_time,
1425 1000*jiffies_to_usecs(1));
1426
1427 if (trans_time < commit_time) {
1428 ktime_t expires = ktime_add_ns(ktime_get(),
1429 commit_time);
1430 set_current_state(TASK_UNINTERRUPTIBLE);
1431 schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
1432 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433 }
1434
Theodore Ts'o512a0042009-03-27 22:14:27 -04001435 if (handle->h_sync)
1436 transaction->t_synchronous_commit = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437 current->journal_info = NULL;
1438 spin_lock(&journal->j_state_lock);
1439 spin_lock(&transaction->t_handle_lock);
1440 transaction->t_outstanding_credits -= handle->h_buffer_credits;
1441 transaction->t_updates--;
1442 if (!transaction->t_updates) {
1443 wake_up(&journal->j_wait_updates);
1444 if (journal->j_barrier_count)
1445 wake_up(&journal->j_wait_transaction_locked);
1446 }
1447
1448 /*
1449 * If the handle is marked SYNC, we need to set another commit
1450 * going! We also want to force a commit if the current
1451 * transaction is occupying too much of the log, or if the
1452 * transaction is too old now.
1453 */
1454 if (handle->h_sync ||
1455 transaction->t_outstanding_credits >
1456 journal->j_max_transaction_buffers ||
Dave Kleikampe9ad5622006-09-27 01:49:35 -07001457 time_after_eq(jiffies, transaction->t_expires)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 /* Do this even for aborted journals: an abort still
1459 * completes the commit thread, it just doesn't write
1460 * anything to disk. */
1461 tid_t tid = transaction->t_tid;
1462
1463 spin_unlock(&transaction->t_handle_lock);
1464 jbd_debug(2, "transaction too old, requesting commit for "
1465 "handle %p\n", handle);
1466 /* This is non-blocking */
1467 __log_start_commit(journal, transaction->t_tid);
1468 spin_unlock(&journal->j_state_lock);
1469
1470 /*
1471 * Special case: JFS_SYNC synchronous updates require us
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001472 * to wait for the commit to complete.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473 */
1474 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1475 err = log_wait_commit(journal, tid);
1476 } else {
1477 spin_unlock(&transaction->t_handle_lock);
1478 spin_unlock(&journal->j_state_lock);
1479 }
1480
Ingo Molnar3295f0e2008-08-11 10:30:30 +02001481 lock_map_release(&handle->h_lockdep_map);
Peter Zijlstra34a3d1e2007-10-11 22:11:12 +02001482
Linus Torvalds1da177e2005-04-16 15:20:36 -07001483 jbd_free_handle(handle);
1484 return err;
1485}
1486
Randy Dunlap0cf01f62008-03-19 17:00:44 -07001487/**
1488 * int journal_force_commit() - force any uncommitted transactions
Linus Torvalds1da177e2005-04-16 15:20:36 -07001489 * @journal: journal to force
1490 *
1491 * For synchronous operations: force any uncommitted transactions
1492 * to disk. May seem kludgy, but it reuses all the handle batching
1493 * code in a very simple manner.
1494 */
1495int journal_force_commit(journal_t *journal)
1496{
1497 handle_t *handle;
1498 int ret;
1499
1500 handle = journal_start(journal, 1);
1501 if (IS_ERR(handle)) {
1502 ret = PTR_ERR(handle);
1503 } else {
1504 handle->h_sync = 1;
1505 ret = journal_stop(handle);
1506 }
1507 return ret;
1508}
1509
1510/*
1511 *
1512 * List management code snippets: various functions for manipulating the
1513 * transaction buffer lists.
1514 *
1515 */
1516
1517/*
1518 * Append a buffer to a transaction list, given the transaction's list head
1519 * pointer.
1520 *
1521 * j_list_lock is held.
1522 *
1523 * jbd_lock_bh_state(jh2bh(jh)) is held.
1524 */
1525
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001526static inline void
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527__blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1528{
1529 if (!*list) {
1530 jh->b_tnext = jh->b_tprev = jh;
1531 *list = jh;
1532 } else {
1533 /* Insert at the tail of the list to preserve order */
1534 struct journal_head *first = *list, *last = first->b_tprev;
1535 jh->b_tprev = last;
1536 jh->b_tnext = first;
1537 last->b_tnext = first->b_tprev = jh;
1538 }
1539}
1540
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001541/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001542 * Remove a buffer from a transaction list, given the transaction's list
1543 * head pointer.
1544 *
1545 * Called with j_list_lock held, and the journal may not be locked.
1546 *
1547 * jbd_lock_bh_state(jh2bh(jh)) is held.
1548 */
1549
1550static inline void
1551__blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1552{
1553 if (*list == jh) {
1554 *list = jh->b_tnext;
1555 if (*list == jh)
1556 *list = NULL;
1557 }
1558 jh->b_tprev->b_tnext = jh->b_tnext;
1559 jh->b_tnext->b_tprev = jh->b_tprev;
1560}
1561
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001562/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001563 * Remove a buffer from the appropriate transaction list.
1564 *
1565 * Note that this function can *change* the value of
1566 * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
1567 * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller
1568 * is holding onto a copy of one of thee pointers, it could go bad.
1569 * Generally the caller needs to re-read the pointer from the transaction_t.
1570 *
1571 * Called under j_list_lock. The journal may not be locked.
1572 */
Adrian Bunkd394e122006-12-06 20:38:26 -08001573static void __journal_temp_unlink_buffer(struct journal_head *jh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574{
1575 struct journal_head **list = NULL;
1576 transaction_t *transaction;
1577 struct buffer_head *bh = jh2bh(jh);
1578
1579 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1580 transaction = jh->b_transaction;
1581 if (transaction)
1582 assert_spin_locked(&transaction->t_journal->j_list_lock);
1583
1584 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1585 if (jh->b_jlist != BJ_None)
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001586 J_ASSERT_JH(jh, transaction != NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587
1588 switch (jh->b_jlist) {
1589 case BJ_None:
1590 return;
1591 case BJ_SyncData:
1592 list = &transaction->t_sync_datalist;
1593 break;
1594 case BJ_Metadata:
1595 transaction->t_nr_buffers--;
1596 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1597 list = &transaction->t_buffers;
1598 break;
1599 case BJ_Forget:
1600 list = &transaction->t_forget;
1601 break;
1602 case BJ_IO:
1603 list = &transaction->t_iobuf_list;
1604 break;
1605 case BJ_Shadow:
1606 list = &transaction->t_shadow_list;
1607 break;
1608 case BJ_LogCtl:
1609 list = &transaction->t_log_list;
1610 break;
1611 case BJ_Reserved:
1612 list = &transaction->t_reserved_list;
1613 break;
1614 case BJ_Locked:
1615 list = &transaction->t_locked_list;
1616 break;
1617 }
1618
1619 __blist_del_buffer(list, jh);
1620 jh->b_jlist = BJ_None;
1621 if (test_clear_buffer_jbddirty(bh))
1622 mark_buffer_dirty(bh); /* Expose it to the VM */
1623}
1624
1625void __journal_unfile_buffer(struct journal_head *jh)
1626{
1627 __journal_temp_unlink_buffer(jh);
1628 jh->b_transaction = NULL;
1629}
1630
1631void journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1632{
1633 jbd_lock_bh_state(jh2bh(jh));
1634 spin_lock(&journal->j_list_lock);
1635 __journal_unfile_buffer(jh);
1636 spin_unlock(&journal->j_list_lock);
1637 jbd_unlock_bh_state(jh2bh(jh));
1638}
1639
1640/*
1641 * Called from journal_try_to_free_buffers().
1642 *
1643 * Called under jbd_lock_bh_state(bh)
1644 */
1645static void
1646__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1647{
1648 struct journal_head *jh;
1649
1650 jh = bh2jh(bh);
1651
1652 if (buffer_locked(bh) || buffer_dirty(bh))
1653 goto out;
1654
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001655 if (jh->b_next_transaction != NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001656 goto out;
1657
1658 spin_lock(&journal->j_list_lock);
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001659 if (jh->b_transaction != NULL && jh->b_cp_transaction == NULL) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660 if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
1661 /* A written-back ordered data buffer */
1662 JBUFFER_TRACE(jh, "release data");
1663 __journal_unfile_buffer(jh);
1664 journal_remove_journal_head(bh);
1665 __brelse(bh);
1666 }
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001667 } else if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001668 /* written-back checkpointed metadata buffer */
1669 if (jh->b_jlist == BJ_None) {
1670 JBUFFER_TRACE(jh, "remove from checkpoint list");
1671 __journal_remove_checkpoint(jh);
1672 journal_remove_journal_head(bh);
1673 __brelse(bh);
1674 }
1675 }
1676 spin_unlock(&journal->j_list_lock);
1677out:
1678 return;
1679}
1680
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001681/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001682 * int journal_try_to_free_buffers() - try to free page buffers.
1683 * @journal: journal for operation
1684 * @page: to try and free
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001685 * @gfp_mask: we use the mask to detect how hard should we try to release
1686 * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to
1687 * release the buffers.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001688 *
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001689 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001690 * For all the buffers on this page,
1691 * if they are fully written out ordered data, move them onto BUF_CLEAN
1692 * so try_to_free_buffers() can reap them.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001693 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001694 * This function returns non-zero if we wish try_to_free_buffers()
1695 * to be called. We do this if the page is releasable by try_to_free_buffers().
1696 * We also do it if the page has locked or dirty buffers and the caller wants
1697 * us to perform sync or async writeout.
1698 *
1699 * This complicates JBD locking somewhat. We aren't protected by the
1700 * BKL here. We wish to remove the buffer from its committing or
1701 * running transaction's ->t_datalist via __journal_unfile_buffer.
1702 *
1703 * This may *change* the value of transaction_t->t_datalist, so anyone
1704 * who looks at t_datalist needs to lock against this function.
1705 *
1706 * Even worse, someone may be doing a journal_dirty_data on this
1707 * buffer. So we need to lock against that. journal_dirty_data()
1708 * will come out of the lock with the buffer dirty, which makes it
1709 * ineligible for release here.
1710 *
1711 * Who else is affected by this? hmm... Really the only contender
1712 * is do_get_write_access() - it could be looking at the buffer while
1713 * journal_try_to_free_buffer() is changing its state. But that
1714 * cannot happen because we never reallocate freed data as metadata
1715 * while the data is part of a transaction. Yes?
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001716 *
1717 * Return 0 on failure, 1 on success
Linus Torvalds1da177e2005-04-16 15:20:36 -07001718 */
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001719int journal_try_to_free_buffers(journal_t *journal,
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001720 struct page *page, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721{
1722 struct buffer_head *head;
1723 struct buffer_head *bh;
1724 int ret = 0;
1725
1726 J_ASSERT(PageLocked(page));
1727
1728 head = page_buffers(page);
1729 bh = head;
1730 do {
1731 struct journal_head *jh;
1732
1733 /*
1734 * We take our own ref against the journal_head here to avoid
1735 * having to add tons of locking around each instance of
1736 * journal_remove_journal_head() and journal_put_journal_head().
1737 */
1738 jh = journal_grab_journal_head(bh);
1739 if (!jh)
1740 continue;
1741
1742 jbd_lock_bh_state(bh);
1743 __journal_try_to_free_buffer(journal, bh);
1744 journal_put_journal_head(jh);
1745 jbd_unlock_bh_state(bh);
1746 if (buffer_jbd(bh))
1747 goto busy;
1748 } while ((bh = bh->b_this_page) != head);
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001749
Linus Torvalds1da177e2005-04-16 15:20:36 -07001750 ret = try_to_free_buffers(page);
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001751
Linus Torvalds1da177e2005-04-16 15:20:36 -07001752busy:
1753 return ret;
1754}
1755
1756/*
1757 * This buffer is no longer needed. If it is on an older transaction's
1758 * checkpoint list we need to record it on this transaction's forget list
1759 * to pin this buffer (and hence its checkpointing transaction) down until
1760 * this transaction commits. If the buffer isn't on a checkpoint list, we
1761 * release it.
1762 * Returns non-zero if JBD no longer has an interest in the buffer.
1763 *
1764 * Called under j_list_lock.
1765 *
1766 * Called under jbd_lock_bh_state(bh).
1767 */
1768static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1769{
1770 int may_free = 1;
1771 struct buffer_head *bh = jh2bh(jh);
1772
1773 __journal_unfile_buffer(jh);
1774
1775 if (jh->b_cp_transaction) {
1776 JBUFFER_TRACE(jh, "on running+cp transaction");
Jan Kara1e9fd532009-06-24 17:31:40 +02001777 /*
1778 * We don't want to write the buffer anymore, clear the
1779 * bit so that we don't confuse checks in
1780 * __journal_file_buffer
1781 */
1782 clear_buffer_dirty(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001783 __journal_file_buffer(jh, transaction, BJ_Forget);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784 may_free = 0;
1785 } else {
1786 JBUFFER_TRACE(jh, "on running transaction");
1787 journal_remove_journal_head(bh);
1788 __brelse(bh);
1789 }
1790 return may_free;
1791}
1792
1793/*
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001794 * journal_invalidatepage
Linus Torvalds1da177e2005-04-16 15:20:36 -07001795 *
1796 * This code is tricky. It has a number of cases to deal with.
1797 *
1798 * There are two invariants which this code relies on:
1799 *
1800 * i_size must be updated on disk before we start calling invalidatepage on the
1801 * data.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001802 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001803 * This is done in ext3 by defining an ext3_setattr method which
1804 * updates i_size before truncate gets going. By maintaining this
1805 * invariant, we can be sure that it is safe to throw away any buffers
1806 * attached to the current transaction: once the transaction commits,
1807 * we know that the data will not be needed.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001808 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001809 * Note however that we can *not* throw away data belonging to the
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001810 * previous, committing transaction!
Linus Torvalds1da177e2005-04-16 15:20:36 -07001811 *
1812 * Any disk blocks which *are* part of the previous, committing
1813 * transaction (and which therefore cannot be discarded immediately) are
1814 * not going to be reused in the new running transaction
1815 *
1816 * The bitmap committed_data images guarantee this: any block which is
1817 * allocated in one transaction and removed in the next will be marked
1818 * as in-use in the committed_data bitmap, so cannot be reused until
1819 * the next transaction to delete the block commits. This means that
1820 * leaving committing buffers dirty is quite safe: the disk blocks
1821 * cannot be reallocated to a different file and so buffer aliasing is
1822 * not possible.
1823 *
1824 *
1825 * The above applies mainly to ordered data mode. In writeback mode we
1826 * don't make guarantees about the order in which data hits disk --- in
1827 * particular we don't guarantee that new dirty data is flushed before
1828 * transaction commit --- so it is always safe just to discard data
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001829 * immediately in that mode. --sct
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830 */
1831
1832/*
1833 * The journal_unmap_buffer helper function returns zero if the buffer
1834 * concerned remains pinned as an anonymous buffer belonging to an older
1835 * transaction.
1836 *
1837 * We're outside-transaction here. Either or both of j_running_transaction
1838 * and j_committing_transaction may be NULL.
1839 */
1840static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1841{
1842 transaction_t *transaction;
1843 struct journal_head *jh;
1844 int may_free = 1;
1845 int ret;
1846
1847 BUFFER_TRACE(bh, "entry");
1848
1849 /*
1850 * It is safe to proceed here without the j_list_lock because the
1851 * buffers cannot be stolen by try_to_free_buffers as long as we are
1852 * holding the page lock. --sct
1853 */
1854
1855 if (!buffer_jbd(bh))
1856 goto zap_buffer_unlocked;
1857
1858 spin_lock(&journal->j_state_lock);
1859 jbd_lock_bh_state(bh);
1860 spin_lock(&journal->j_list_lock);
1861
1862 jh = journal_grab_journal_head(bh);
1863 if (!jh)
1864 goto zap_buffer_no_jh;
1865
1866 transaction = jh->b_transaction;
1867 if (transaction == NULL) {
1868 /* First case: not on any transaction. If it
1869 * has no checkpoint link, then we can zap it:
1870 * it's a writeback-mode buffer so we don't care
1871 * if it hits disk safely. */
1872 if (!jh->b_cp_transaction) {
1873 JBUFFER_TRACE(jh, "not on any transaction: zap");
1874 goto zap_buffer;
1875 }
1876
1877 if (!buffer_dirty(bh)) {
1878 /* bdflush has written it. We can drop it now */
1879 goto zap_buffer;
1880 }
1881
1882 /* OK, it must be in the journal but still not
1883 * written fully to disk: it's metadata or
1884 * journaled data... */
1885
1886 if (journal->j_running_transaction) {
1887 /* ... and once the current transaction has
1888 * committed, the buffer won't be needed any
1889 * longer. */
1890 JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1891 ret = __dispose_buffer(jh,
1892 journal->j_running_transaction);
1893 journal_put_journal_head(jh);
1894 spin_unlock(&journal->j_list_lock);
1895 jbd_unlock_bh_state(bh);
1896 spin_unlock(&journal->j_state_lock);
1897 return ret;
1898 } else {
1899 /* There is no currently-running transaction. So the
1900 * orphan record which we wrote for this file must have
1901 * passed into commit. We must attach this buffer to
1902 * the committing transaction, if it exists. */
1903 if (journal->j_committing_transaction) {
1904 JBUFFER_TRACE(jh, "give to committing trans");
1905 ret = __dispose_buffer(jh,
1906 journal->j_committing_transaction);
1907 journal_put_journal_head(jh);
1908 spin_unlock(&journal->j_list_lock);
1909 jbd_unlock_bh_state(bh);
1910 spin_unlock(&journal->j_state_lock);
1911 return ret;
1912 } else {
1913 /* The orphan record's transaction has
1914 * committed. We can cleanse this buffer */
1915 clear_buffer_jbddirty(bh);
1916 goto zap_buffer;
1917 }
1918 }
1919 } else if (transaction == journal->j_committing_transaction) {
Eric Sandeenf58a74d2006-10-28 10:38:27 -07001920 JBUFFER_TRACE(jh, "on committing transaction");
akpm@osdl.orgd13df842005-04-16 15:26:36 -07001921 if (jh->b_jlist == BJ_Locked) {
1922 /*
1923 * The buffer is on the committing transaction's locked
1924 * list. We have the buffer locked, so I/O has
1925 * completed. So we can nail the buffer now.
1926 */
1927 may_free = __dispose_buffer(jh, transaction);
1928 goto zap_buffer;
1929 }
1930 /*
1931 * If it is committing, we simply cannot touch it. We
Linus Torvalds1da177e2005-04-16 15:20:36 -07001932 * can remove it's next_transaction pointer from the
1933 * running transaction if that is set, but nothing
1934 * else. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001935 set_buffer_freed(bh);
1936 if (jh->b_next_transaction) {
1937 J_ASSERT(jh->b_next_transaction ==
1938 journal->j_running_transaction);
1939 jh->b_next_transaction = NULL;
1940 }
1941 journal_put_journal_head(jh);
1942 spin_unlock(&journal->j_list_lock);
1943 jbd_unlock_bh_state(bh);
1944 spin_unlock(&journal->j_state_lock);
1945 return 0;
1946 } else {
1947 /* Good, the buffer belongs to the running transaction.
1948 * We are writing our own transaction's data, not any
1949 * previous one's, so it is safe to throw it away
1950 * (remember that we expect the filesystem to have set
1951 * i_size already for this truncate so recovery will not
1952 * expose the disk blocks we are discarding here.) */
1953 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
Eric Sandeenf58a74d2006-10-28 10:38:27 -07001954 JBUFFER_TRACE(jh, "on running transaction");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001955 may_free = __dispose_buffer(jh, transaction);
1956 }
1957
1958zap_buffer:
1959 journal_put_journal_head(jh);
1960zap_buffer_no_jh:
1961 spin_unlock(&journal->j_list_lock);
1962 jbd_unlock_bh_state(bh);
1963 spin_unlock(&journal->j_state_lock);
1964zap_buffer_unlocked:
1965 clear_buffer_dirty(bh);
1966 J_ASSERT_BH(bh, !buffer_jbddirty(bh));
1967 clear_buffer_mapped(bh);
1968 clear_buffer_req(bh);
1969 clear_buffer_new(bh);
1970 bh->b_bdev = NULL;
1971 return may_free;
1972}
1973
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001974/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07001975 * void journal_invalidatepage() - invalidate a journal page
1976 * @journal: journal to use for flush
Linus Torvalds1da177e2005-04-16 15:20:36 -07001977 * @page: page to flush
1978 * @offset: length of page to invalidate.
1979 *
1980 * Reap page buffers containing data after offset in page.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001981 */
NeilBrown2ff28e22006-03-26 01:37:18 -08001982void journal_invalidatepage(journal_t *journal,
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001983 struct page *page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001984 unsigned long offset)
1985{
1986 struct buffer_head *head, *bh, *next;
1987 unsigned int curr_off = 0;
1988 int may_free = 1;
1989
1990 if (!PageLocked(page))
1991 BUG();
1992 if (!page_has_buffers(page))
NeilBrown2ff28e22006-03-26 01:37:18 -08001993 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001994
1995 /* We will potentially be playing with lists other than just the
1996 * data lists (especially for journaled data mode), so be
1997 * cautious in our locking. */
1998
1999 head = bh = page_buffers(page);
2000 do {
2001 unsigned int next_off = curr_off + bh->b_size;
2002 next = bh->b_this_page;
2003
Linus Torvalds1da177e2005-04-16 15:20:36 -07002004 if (offset <= curr_off) {
Dave Kleikampe9ad5622006-09-27 01:49:35 -07002005 /* This block is wholly outside the truncation point */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002006 lock_buffer(bh);
2007 may_free &= journal_unmap_buffer(journal, bh);
2008 unlock_buffer(bh);
2009 }
2010 curr_off = next_off;
2011 bh = next;
2012
2013 } while (bh != head);
2014
2015 if (!offset) {
NeilBrown2ff28e22006-03-26 01:37:18 -08002016 if (may_free && try_to_free_buffers(page))
2017 J_ASSERT(!page_has_buffers(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002018 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002019}
2020
Mingming Caoae6ddcc2006-09-27 01:49:27 -07002021/*
2022 * File a buffer on the given transaction list.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002023 */
2024void __journal_file_buffer(struct journal_head *jh,
2025 transaction_t *transaction, int jlist)
2026{
2027 struct journal_head **list = NULL;
2028 int was_dirty = 0;
2029 struct buffer_head *bh = jh2bh(jh);
2030
2031 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2032 assert_spin_locked(&transaction->t_journal->j_list_lock);
2033
2034 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
2035 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07002036 jh->b_transaction == NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002037
2038 if (jh->b_transaction && jh->b_jlist == jlist)
2039 return;
2040
Mingming Caoae6ddcc2006-09-27 01:49:27 -07002041 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07002042 jlist == BJ_Shadow || jlist == BJ_Forget) {
Jan Kara1e9fd532009-06-24 17:31:40 +02002043 /*
2044 * For metadata buffers, we track dirty bit in buffer_jbddirty
2045 * instead of buffer_dirty. We should not see a dirty bit set
2046 * here because we clear it in do_get_write_access but e.g.
2047 * tune2fs can modify the sb and set the dirty bit at any time
2048 * so we try to gracefully handle that.
2049 */
2050 if (buffer_dirty(bh))
2051 warn_dirty_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002052 if (test_clear_buffer_dirty(bh) ||
2053 test_clear_buffer_jbddirty(bh))
2054 was_dirty = 1;
2055 }
2056
2057 if (jh->b_transaction)
2058 __journal_temp_unlink_buffer(jh);
2059 jh->b_transaction = transaction;
2060
2061 switch (jlist) {
2062 case BJ_None:
2063 J_ASSERT_JH(jh, !jh->b_committed_data);
2064 J_ASSERT_JH(jh, !jh->b_frozen_data);
2065 return;
2066 case BJ_SyncData:
2067 list = &transaction->t_sync_datalist;
2068 break;
2069 case BJ_Metadata:
2070 transaction->t_nr_buffers++;
2071 list = &transaction->t_buffers;
2072 break;
2073 case BJ_Forget:
2074 list = &transaction->t_forget;
2075 break;
2076 case BJ_IO:
2077 list = &transaction->t_iobuf_list;
2078 break;
2079 case BJ_Shadow:
2080 list = &transaction->t_shadow_list;
2081 break;
2082 case BJ_LogCtl:
2083 list = &transaction->t_log_list;
2084 break;
2085 case BJ_Reserved:
2086 list = &transaction->t_reserved_list;
2087 break;
2088 case BJ_Locked:
2089 list = &transaction->t_locked_list;
2090 break;
2091 }
2092
2093 __blist_add_buffer(list, jh);
2094 jh->b_jlist = jlist;
2095
2096 if (was_dirty)
2097 set_buffer_jbddirty(bh);
2098}
2099
2100void journal_file_buffer(struct journal_head *jh,
2101 transaction_t *transaction, int jlist)
2102{
2103 jbd_lock_bh_state(jh2bh(jh));
2104 spin_lock(&transaction->t_journal->j_list_lock);
2105 __journal_file_buffer(jh, transaction, jlist);
2106 spin_unlock(&transaction->t_journal->j_list_lock);
2107 jbd_unlock_bh_state(jh2bh(jh));
2108}
2109
Mingming Caoae6ddcc2006-09-27 01:49:27 -07002110/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002111 * Remove a buffer from its current buffer list in preparation for
2112 * dropping it from its current transaction entirely. If the buffer has
2113 * already started to be used by a subsequent transaction, refile the
2114 * buffer on that transaction's metadata list.
2115 *
2116 * Called under journal->j_list_lock
2117 *
2118 * Called under jbd_lock_bh_state(jh2bh(jh))
2119 */
2120void __journal_refile_buffer(struct journal_head *jh)
2121{
2122 int was_dirty;
2123 struct buffer_head *bh = jh2bh(jh);
2124
2125 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2126 if (jh->b_transaction)
2127 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2128
2129 /* If the buffer is now unused, just drop it. */
2130 if (jh->b_next_transaction == NULL) {
2131 __journal_unfile_buffer(jh);
2132 return;
2133 }
2134
2135 /*
2136 * It has been modified by a later transaction: add it to the new
2137 * transaction's metadata list.
2138 */
2139
2140 was_dirty = test_clear_buffer_jbddirty(bh);
2141 __journal_temp_unlink_buffer(jh);
2142 jh->b_transaction = jh->b_next_transaction;
2143 jh->b_next_transaction = NULL;
Jan Kara9ada7342006-06-23 02:05:25 -07002144 __journal_file_buffer(jh, jh->b_transaction,
Josef Bacik5b9a4992008-04-28 02:16:12 -07002145 jh->b_modified ? BJ_Metadata : BJ_Reserved);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146 J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2147
2148 if (was_dirty)
2149 set_buffer_jbddirty(bh);
2150}
2151
2152/*
2153 * For the unlocked version of this call, also make sure that any
2154 * hanging journal_head is cleaned up if necessary.
2155 *
2156 * __journal_refile_buffer is usually called as part of a single locked
2157 * operation on a buffer_head, in which the caller is probably going to
2158 * be hooking the journal_head onto other lists. In that case it is up
2159 * to the caller to remove the journal_head if necessary. For the
2160 * unlocked journal_refile_buffer call, the caller isn't going to be
2161 * doing anything else to the buffer so we need to do the cleanup
Mingming Caoae6ddcc2006-09-27 01:49:27 -07002162 * ourselves to avoid a jh leak.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002163 *
2164 * *** The journal_head may be freed by this call! ***
2165 */
2166void journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2167{
2168 struct buffer_head *bh = jh2bh(jh);
2169
2170 jbd_lock_bh_state(bh);
2171 spin_lock(&journal->j_list_lock);
2172
2173 __journal_refile_buffer(jh);
2174 jbd_unlock_bh_state(bh);
2175 journal_remove_journal_head(bh);
2176
2177 spin_unlock(&journal->j_list_lock);
2178 __brelse(bh);
2179}