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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
492/*
493 * Report any unexpected dirty buffers which turn up. Normally those
494 * indicate an error, but they can occur if the user is running (say)
495 * tune2fs to modify the live filesystem, so we need the option of
496 * continuing as gracefully as possible. #
497 *
498 * The caller should already hold the journal lock and
499 * j_list_lock spinlock: most callers will need those anyway
500 * in order to probe the buffer's journaling state safely.
501 */
502static void jbd_unexpected_dirty_buffer(struct journal_head *jh)
503{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 int jlist;
505
Jan Kara4407c2b2005-09-06 15:19:17 -0700506 /* If this buffer is one which might reasonably be dirty
507 * --- ie. data, or not part of this journal --- then
508 * we're OK to leave it alone, but otherwise we need to
509 * move the dirty bit to the journal's own internal
510 * JBDDirty bit. */
511 jlist = jh->b_jlist;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512
Jan Kara4407c2b2005-09-06 15:19:17 -0700513 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
514 jlist == BJ_Shadow || jlist == BJ_Forget) {
515 struct buffer_head *bh = jh2bh(jh);
516
517 if (test_clear_buffer_dirty(bh))
518 set_buffer_jbddirty(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519 }
520}
521
522/*
523 * If the buffer is already part of the current transaction, then there
524 * is nothing we need to do. If it is already part of a prior
525 * transaction which we are still committing to disk, then we need to
526 * make sure that we do not overwrite the old copy: we do copy-out to
527 * preserve the copy going to disk. We also account the buffer against
528 * the handle's metadata buffer credits (unless the buffer is already
529 * part of the transaction, that is).
530 *
531 */
532static int
533do_get_write_access(handle_t *handle, struct journal_head *jh,
534 int force_copy)
535{
536 struct buffer_head *bh;
537 transaction_t *transaction;
538 journal_t *journal;
539 int error;
540 char *frozen_buffer = NULL;
541 int need_copy = 0;
542
543 if (is_handle_aborted(handle))
544 return -EROFS;
545
546 transaction = handle->h_transaction;
547 journal = transaction->t_journal;
548
549 jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy);
550
551 JBUFFER_TRACE(jh, "entry");
552repeat:
553 bh = jh2bh(jh);
554
555 /* @@@ Need to check for errors here at some point. */
556
557 lock_buffer(bh);
558 jbd_lock_bh_state(bh);
559
560 /* We now hold the buffer lock so it is safe to query the buffer
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700561 * state. Is the buffer dirty?
562 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563 * If so, there are two possibilities. The buffer may be
564 * non-journaled, and undergoing a quite legitimate writeback.
565 * Otherwise, it is journaled, and we don't expect dirty buffers
566 * in that state (the buffers should be marked JBD_Dirty
567 * instead.) So either the IO is being done under our own
568 * control and this is a bug, or it's a third party IO such as
569 * dump(8) (which may leave the buffer scheduled for read ---
570 * ie. locked but not dirty) or tune2fs (which may actually have
571 * the buffer dirtied, ugh.) */
572
573 if (buffer_dirty(bh)) {
574 /*
575 * First question: is this buffer already part of the current
576 * transaction or the existing committing transaction?
577 */
578 if (jh->b_transaction) {
579 J_ASSERT_JH(jh,
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700580 jh->b_transaction == transaction ||
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 jh->b_transaction ==
582 journal->j_committing_transaction);
583 if (jh->b_next_transaction)
584 J_ASSERT_JH(jh, jh->b_next_transaction ==
585 transaction);
Jan Kara4407c2b2005-09-06 15:19:17 -0700586 }
587 /*
588 * In any case we need to clean the dirty flag and we must
589 * do it under the buffer lock to be sure we don't race
590 * with running write-out.
591 */
592 JBUFFER_TRACE(jh, "Unexpected dirty buffer");
593 jbd_unexpected_dirty_buffer(jh);
Dave Kleikampe9ad5622006-09-27 01:49:35 -0700594 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595
596 unlock_buffer(bh);
597
598 error = -EROFS;
599 if (is_handle_aborted(handle)) {
600 jbd_unlock_bh_state(bh);
601 goto out;
602 }
603 error = 0;
604
605 /*
606 * The buffer is already part of this transaction if b_transaction or
607 * b_next_transaction points to it
608 */
609 if (jh->b_transaction == transaction ||
610 jh->b_next_transaction == transaction)
611 goto done;
612
613 /*
Josef Bacik5bc833f2008-04-28 02:16:10 -0700614 * this is the first time this transaction is touching this buffer,
615 * reset the modified flag
616 */
617 jh->b_modified = 0;
618
619 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620 * If there is already a copy-out version of this buffer, then we don't
621 * need to make another one
622 */
623 if (jh->b_frozen_data) {
624 JBUFFER_TRACE(jh, "has frozen data");
625 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
626 jh->b_next_transaction = transaction;
627 goto done;
628 }
629
630 /* Is there data here we need to preserve? */
631
632 if (jh->b_transaction && jh->b_transaction != transaction) {
633 JBUFFER_TRACE(jh, "owned by older transaction");
634 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
635 J_ASSERT_JH(jh, jh->b_transaction ==
636 journal->j_committing_transaction);
637
638 /* There is one case we have to be very careful about.
639 * If the committing transaction is currently writing
640 * this buffer out to disk and has NOT made a copy-out,
641 * then we cannot modify the buffer contents at all
642 * right now. The essence of copy-out is that it is the
643 * extra copy, not the primary copy, which gets
644 * journaled. If the primary copy is already going to
645 * disk then we cannot do copy-out here. */
646
647 if (jh->b_jlist == BJ_Shadow) {
648 DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
649 wait_queue_head_t *wqh;
650
651 wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
652
653 JBUFFER_TRACE(jh, "on shadow: sleep");
654 jbd_unlock_bh_state(bh);
655 /* commit wakes up all shadow buffers after IO */
656 for ( ; ; ) {
657 prepare_to_wait(wqh, &wait.wait,
658 TASK_UNINTERRUPTIBLE);
659 if (jh->b_jlist != BJ_Shadow)
660 break;
661 schedule();
662 }
663 finish_wait(wqh, &wait.wait);
664 goto repeat;
665 }
666
667 /* Only do the copy if the currently-owning transaction
668 * still needs it. If it is on the Forget list, the
669 * committing transaction is past that stage. The
670 * buffer had better remain locked during the kmalloc,
671 * but that should be true --- we hold the journal lock
672 * still and the buffer is already on the BUF_JOURNAL
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700673 * list so won't be flushed.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674 *
675 * Subtle point, though: if this is a get_undo_access,
676 * then we will be relying on the frozen_data to contain
677 * the new value of the committed_data record after the
678 * transaction, so we HAVE to force the frozen_data copy
679 * in that case. */
680
681 if (jh->b_jlist != BJ_Forget || force_copy) {
682 JBUFFER_TRACE(jh, "generate frozen data");
683 if (!frozen_buffer) {
684 JBUFFER_TRACE(jh, "allocate memory for buffer");
685 jbd_unlock_bh_state(bh);
Badari Pulavartyea817392006-08-27 01:23:52 -0700686 frozen_buffer =
Mingming Caoc089d492007-10-16 18:38:25 -0400687 jbd_alloc(jh2bh(jh)->b_size,
Badari Pulavartyea817392006-08-27 01:23:52 -0700688 GFP_NOFS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689 if (!frozen_buffer) {
690 printk(KERN_EMERG
691 "%s: OOM for frozen_buffer\n",
Harvey Harrison08fc99b2008-04-28 02:16:16 -0700692 __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 JBUFFER_TRACE(jh, "oom!");
694 error = -ENOMEM;
695 jbd_lock_bh_state(bh);
696 goto done;
697 }
698 goto repeat;
699 }
700 jh->b_frozen_data = frozen_buffer;
701 frozen_buffer = NULL;
702 need_copy = 1;
703 }
704 jh->b_next_transaction = transaction;
705 }
706
707
708 /*
709 * Finally, if the buffer is not journaled right now, we need to make
710 * sure it doesn't get written to disk before the caller actually
711 * commits the new data
712 */
713 if (!jh->b_transaction) {
714 JBUFFER_TRACE(jh, "no transaction");
715 J_ASSERT_JH(jh, !jh->b_next_transaction);
716 jh->b_transaction = transaction;
717 JBUFFER_TRACE(jh, "file as BJ_Reserved");
718 spin_lock(&journal->j_list_lock);
719 __journal_file_buffer(jh, transaction, BJ_Reserved);
720 spin_unlock(&journal->j_list_lock);
721 }
722
723done:
724 if (need_copy) {
725 struct page *page;
726 int offset;
727 char *source;
728
729 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
730 "Possible IO failure.\n");
731 page = jh2bh(jh)->b_page;
732 offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK;
733 source = kmap_atomic(page, KM_USER0);
734 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
735 kunmap_atomic(source, KM_USER0);
736 }
737 jbd_unlock_bh_state(bh);
738
739 /*
740 * If we are about to journal a buffer, then any revoke pending on it is
741 * no longer valid
742 */
743 journal_cancel_revoke(handle, jh);
744
745out:
Andrew Morton304c4c82006-06-23 02:05:31 -0700746 if (unlikely(frozen_buffer)) /* It's usually NULL */
Mingming Caoc089d492007-10-16 18:38:25 -0400747 jbd_free(frozen_buffer, bh->b_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748
749 JBUFFER_TRACE(jh, "exit");
750 return error;
751}
752
753/**
754 * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
755 * @handle: transaction to add buffer modifications to
756 * @bh: bh to be used for metadata writes
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757 *
758 * Returns an error code or 0 on success.
759 *
760 * In full data journalling mode the buffer may be of type BJ_AsyncData,
761 * because we're write()ing a buffer which is also part of a shared mapping.
762 */
763
764int journal_get_write_access(handle_t *handle, struct buffer_head *bh)
765{
766 struct journal_head *jh = journal_add_journal_head(bh);
767 int rc;
768
769 /* We do not want to get caught playing with fields which the
770 * log thread also manipulates. Make sure that the buffer
771 * completes any outstanding IO before proceeding. */
772 rc = do_get_write_access(handle, jh, 0);
773 journal_put_journal_head(jh);
774 return rc;
775}
776
777
778/*
779 * When the user wants to journal a newly created buffer_head
780 * (ie. getblk() returned a new buffer and we are going to populate it
781 * manually rather than reading off disk), then we need to keep the
782 * buffer_head locked until it has been completely filled with new
783 * data. In this case, we should be able to make the assertion that
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700784 * the bh is not already part of an existing transaction.
785 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786 * The buffer should already be locked by the caller by this point.
787 * There is no lock ranking violation: it was a newly created,
788 * unlocked buffer beforehand. */
789
790/**
791 * int journal_get_create_access () - notify intent to use newly created bh
792 * @handle: transaction to new buffer to
793 * @bh: new buffer.
794 *
795 * Call this if you create a new bh.
796 */
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700797int journal_get_create_access(handle_t *handle, struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798{
799 transaction_t *transaction = handle->h_transaction;
800 journal_t *journal = transaction->t_journal;
801 struct journal_head *jh = journal_add_journal_head(bh);
802 int err;
803
804 jbd_debug(5, "journal_head %p\n", jh);
805 err = -EROFS;
806 if (is_handle_aborted(handle))
807 goto out;
808 err = 0;
809
810 JBUFFER_TRACE(jh, "entry");
811 /*
812 * The buffer may already belong to this transaction due to pre-zeroing
813 * in the filesystem's new_block code. It may also be on the previous,
814 * committing transaction's lists, but it HAS to be in Forget state in
815 * that case: the transaction must have deleted the buffer for it to be
816 * reused here.
817 */
818 jbd_lock_bh_state(bh);
819 spin_lock(&journal->j_list_lock);
820 J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
821 jh->b_transaction == NULL ||
822 (jh->b_transaction == journal->j_committing_transaction &&
823 jh->b_jlist == BJ_Forget)));
824
825 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
826 J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
827
828 if (jh->b_transaction == NULL) {
829 jh->b_transaction = transaction;
Josef Bacik5bc833f2008-04-28 02:16:10 -0700830
831 /* first access by this transaction */
832 jh->b_modified = 0;
833
Linus Torvalds1da177e2005-04-16 15:20:36 -0700834 JBUFFER_TRACE(jh, "file as BJ_Reserved");
835 __journal_file_buffer(jh, transaction, BJ_Reserved);
836 } else if (jh->b_transaction == journal->j_committing_transaction) {
Josef Bacik5bc833f2008-04-28 02:16:10 -0700837 /* first access by this transaction */
838 jh->b_modified = 0;
839
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840 JBUFFER_TRACE(jh, "set next transaction");
841 jh->b_next_transaction = transaction;
842 }
843 spin_unlock(&journal->j_list_lock);
844 jbd_unlock_bh_state(bh);
845
846 /*
847 * akpm: I added this. ext3_alloc_branch can pick up new indirect
848 * blocks which contain freed but then revoked metadata. We need
849 * to cancel the revoke in case we end up freeing it yet again
850 * and the reallocating as data - this would cause a second revoke,
851 * which hits an assertion error.
852 */
853 JBUFFER_TRACE(jh, "cancelling revoke");
854 journal_cancel_revoke(handle, jh);
855 journal_put_journal_head(jh);
856out:
857 return err;
858}
859
860/**
Randy Dunlap78a4a502008-02-29 22:02:31 -0800861 * int journal_get_undo_access() - Notify intent to modify metadata with non-rewindable consequences
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 * @handle: transaction
863 * @bh: buffer to undo
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864 *
865 * Sometimes there is a need to distinguish between metadata which has
866 * been committed to disk and that which has not. The ext3fs code uses
867 * this for freeing and allocating space, we have to make sure that we
868 * do not reuse freed space until the deallocation has been committed,
869 * since if we overwrote that space we would make the delete
870 * un-rewindable in case of a crash.
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700871 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872 * To deal with that, journal_get_undo_access requests write access to a
873 * buffer for parts of non-rewindable operations such as delete
874 * operations on the bitmaps. The journaling code must keep a copy of
875 * the buffer's contents prior to the undo_access call until such time
876 * as we know that the buffer has definitely been committed to disk.
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700877 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700878 * We never need to know which transaction the committed data is part
879 * of, buffers touched here are guaranteed to be dirtied later and so
880 * will be committed to a new transaction in due course, at which point
881 * we can discard the old committed data pointer.
882 *
883 * Returns error number or 0 on success.
884 */
885int journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
886{
887 int err;
888 struct journal_head *jh = journal_add_journal_head(bh);
889 char *committed_data = NULL;
890
891 JBUFFER_TRACE(jh, "entry");
892
893 /*
894 * Do this first --- it can drop the journal lock, so we want to
895 * make sure that obtaining the committed_data is done
896 * atomically wrt. completion of any outstanding commits.
897 */
898 err = do_get_write_access(handle, jh, 1);
899 if (err)
900 goto out;
901
902repeat:
903 if (!jh->b_committed_data) {
Mingming Caoc089d492007-10-16 18:38:25 -0400904 committed_data = jbd_alloc(jh2bh(jh)->b_size, GFP_NOFS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700905 if (!committed_data) {
906 printk(KERN_EMERG "%s: No memory for committed data\n",
Harvey Harrison08fc99b2008-04-28 02:16:16 -0700907 __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 err = -ENOMEM;
909 goto out;
910 }
911 }
912
913 jbd_lock_bh_state(bh);
914 if (!jh->b_committed_data) {
915 /* Copy out the current buffer contents into the
916 * preserved, committed copy. */
917 JBUFFER_TRACE(jh, "generate b_committed data");
918 if (!committed_data) {
919 jbd_unlock_bh_state(bh);
920 goto repeat;
921 }
922
923 jh->b_committed_data = committed_data;
924 committed_data = NULL;
925 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
926 }
927 jbd_unlock_bh_state(bh);
928out:
929 journal_put_journal_head(jh);
Andrew Morton304c4c82006-06-23 02:05:31 -0700930 if (unlikely(committed_data))
Mingming Caoc089d492007-10-16 18:38:25 -0400931 jbd_free(committed_data, bh->b_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932 return err;
933}
934
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700935/**
Randy Dunlap78a4a502008-02-29 22:02:31 -0800936 * int journal_dirty_data() - mark a buffer as containing dirty data to be flushed
Linus Torvalds1da177e2005-04-16 15:20:36 -0700937 * @handle: transaction
938 * @bh: bufferhead to mark
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700939 *
Randy Dunlap78a4a502008-02-29 22:02:31 -0800940 * Description:
941 * Mark a buffer as containing dirty data which needs to be flushed before
942 * we can commit the current transaction.
943 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944 * The buffer is placed on the transaction's data list and is marked as
945 * belonging to the transaction.
946 *
947 * Returns error number or 0 on success.
948 *
949 * journal_dirty_data() can be called via page_launder->ext3_writepage
950 * by kswapd.
951 */
952int journal_dirty_data(handle_t *handle, struct buffer_head *bh)
953{
954 journal_t *journal = handle->h_transaction->t_journal;
955 int need_brelse = 0;
956 struct journal_head *jh;
Hidehiro Kawai960a22a2008-10-18 20:27:58 -0700957 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700958
959 if (is_handle_aborted(handle))
Hidehiro Kawai960a22a2008-10-18 20:27:58 -0700960 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961
962 jh = journal_add_journal_head(bh);
963 JBUFFER_TRACE(jh, "entry");
964
965 /*
966 * The buffer could *already* be dirty. Writeout can start
967 * at any time.
968 */
969 jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
970
971 /*
972 * What if the buffer is already part of a running transaction?
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700973 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974 * There are two cases:
975 * 1) It is part of the current running transaction. Refile it,
976 * just in case we have allocated it as metadata, deallocated
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700977 * it, then reallocated it as data.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700978 * 2) It is part of the previous, still-committing transaction.
979 * If all we want to do is to guarantee that the buffer will be
980 * written to disk before this new transaction commits, then
Mingming Caoae6ddcc2006-09-27 01:49:27 -0700981 * being sure that the *previous* transaction has this same
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982 * property is sufficient for us! Just leave it on its old
983 * transaction.
984 *
985 * In case (2), the buffer must not already exist as metadata
986 * --- that would violate write ordering (a transaction is free
987 * to write its data at any point, even before the previous
988 * committing transaction has committed). The caller must
989 * never, ever allow this to happen: there's nothing we can do
990 * about it in this layer.
991 */
992 jbd_lock_bh_state(bh);
993 spin_lock(&journal->j_list_lock);
Eric Sandeenf58a74d2006-10-28 10:38:27 -0700994
995 /* Now that we have bh_state locked, are we really still mapped? */
996 if (!buffer_mapped(bh)) {
997 JBUFFER_TRACE(jh, "unmapped buffer, bailing out");
998 goto no_journal;
999 }
1000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001 if (jh->b_transaction) {
1002 JBUFFER_TRACE(jh, "has transaction");
1003 if (jh->b_transaction != handle->h_transaction) {
1004 JBUFFER_TRACE(jh, "belongs to older transaction");
1005 J_ASSERT_JH(jh, jh->b_transaction ==
1006 journal->j_committing_transaction);
1007
1008 /* @@@ IS THIS TRUE ? */
1009 /*
1010 * Not any more. Scenario: someone does a write()
1011 * in data=journal mode. The buffer's transaction has
1012 * moved into commit. Then someone does another
1013 * write() to the file. We do the frozen data copyout
1014 * and set b_next_transaction to point to j_running_t.
1015 * And while we're in that state, someone does a
1016 * writepage() in an attempt to pageout the same area
1017 * of the file via a shared mapping. At present that
1018 * calls journal_dirty_data(), and we get right here.
1019 * It may be too late to journal the data. Simply
1020 * falling through to the next test will suffice: the
1021 * data will be dirty and wil be checkpointed. The
1022 * ordering comments in the next comment block still
1023 * apply.
1024 */
1025 //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1026
1027 /*
1028 * If we're journalling data, and this buffer was
1029 * subject to a write(), it could be metadata, forget
1030 * or shadow against the committing transaction. Now,
1031 * someone has dirtied the same darn page via a mapping
1032 * and it is being writepage()'d.
1033 * We *could* just steal the page from commit, with some
1034 * fancy locking there. Instead, we just skip it -
1035 * don't tie the page's buffers to the new transaction
1036 * at all.
1037 * Implication: if we crash before the writepage() data
1038 * is written into the filesystem, recovery will replay
1039 * the write() data.
1040 */
1041 if (jh->b_jlist != BJ_None &&
1042 jh->b_jlist != BJ_SyncData &&
1043 jh->b_jlist != BJ_Locked) {
1044 JBUFFER_TRACE(jh, "Not stealing");
1045 goto no_journal;
1046 }
1047
1048 /*
1049 * This buffer may be undergoing writeout in commit. We
1050 * can't return from here and let the caller dirty it
1051 * again because that can cause the write-out loop in
1052 * commit to never terminate.
1053 */
1054 if (buffer_dirty(bh)) {
1055 get_bh(bh);
1056 spin_unlock(&journal->j_list_lock);
1057 jbd_unlock_bh_state(bh);
1058 need_brelse = 1;
1059 sync_dirty_buffer(bh);
1060 jbd_lock_bh_state(bh);
1061 spin_lock(&journal->j_list_lock);
Eric Sandeenf58a74d2006-10-28 10:38:27 -07001062 /* Since we dropped the lock... */
1063 if (!buffer_mapped(bh)) {
1064 JBUFFER_TRACE(jh, "buffer got unmapped");
1065 goto no_journal;
1066 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067 /* The buffer may become locked again at any
1068 time if it is redirtied */
1069 }
1070
Hidehiro Kawai960a22a2008-10-18 20:27:58 -07001071 /*
1072 * We cannot remove the buffer with io error from the
1073 * committing transaction, because otherwise it would
1074 * miss the error and the commit would not abort.
1075 */
1076 if (unlikely(!buffer_uptodate(bh))) {
1077 ret = -EIO;
1078 goto no_journal;
1079 }
1080
Linus Torvalds1da177e2005-04-16 15:20:36 -07001081 if (jh->b_transaction != NULL) {
1082 JBUFFER_TRACE(jh, "unfile from commit");
1083 __journal_temp_unlink_buffer(jh);
1084 /* It still points to the committing
1085 * transaction; move it to this one so
1086 * that the refile assert checks are
1087 * happy. */
1088 jh->b_transaction = handle->h_transaction;
1089 }
1090 /* The buffer will be refiled below */
1091
1092 }
1093 /*
1094 * Special case --- the buffer might actually have been
1095 * allocated and then immediately deallocated in the previous,
1096 * committing transaction, so might still be left on that
1097 * transaction's metadata lists.
1098 */
1099 if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
1100 JBUFFER_TRACE(jh, "not on correct data list: unfile");
1101 J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
1102 __journal_temp_unlink_buffer(jh);
1103 jh->b_transaction = handle->h_transaction;
1104 JBUFFER_TRACE(jh, "file as data");
1105 __journal_file_buffer(jh, handle->h_transaction,
1106 BJ_SyncData);
1107 }
1108 } else {
1109 JBUFFER_TRACE(jh, "not on a transaction");
1110 __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
1111 }
1112no_journal:
1113 spin_unlock(&journal->j_list_lock);
1114 jbd_unlock_bh_state(bh);
1115 if (need_brelse) {
1116 BUFFER_TRACE(bh, "brelse");
1117 __brelse(bh);
1118 }
1119 JBUFFER_TRACE(jh, "exit");
1120 journal_put_journal_head(jh);
Hidehiro Kawai960a22a2008-10-18 20:27:58 -07001121 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122}
1123
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001124/**
Randy Dunlap78a4a502008-02-29 22:02:31 -08001125 * int journal_dirty_metadata() - mark a buffer as containing dirty metadata
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126 * @handle: transaction to add buffer to.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001127 * @bh: buffer to mark
1128 *
Randy Dunlap78a4a502008-02-29 22:02:31 -08001129 * Mark dirty metadata which needs to be journaled as part of the current
Linus Torvalds1da177e2005-04-16 15:20:36 -07001130 * transaction.
1131 *
1132 * The buffer is placed on the transaction's metadata list and is marked
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001133 * as belonging to the transaction.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001134 *
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001135 * Returns error number or 0 on success.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001136 *
1137 * Special care needs to be taken if the buffer already belongs to the
1138 * current committing transaction (in which case we should have frozen
1139 * data present for that commit). In that case, we don't relink the
1140 * buffer: that only gets done when the old transaction finally
1141 * completes its commit.
1142 */
1143int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1144{
1145 transaction_t *transaction = handle->h_transaction;
1146 journal_t *journal = transaction->t_journal;
1147 struct journal_head *jh = bh2jh(bh);
1148
1149 jbd_debug(5, "journal_head %p\n", jh);
1150 JBUFFER_TRACE(jh, "entry");
1151 if (is_handle_aborted(handle))
1152 goto out;
1153
1154 jbd_lock_bh_state(bh);
1155
1156 if (jh->b_modified == 0) {
1157 /*
1158 * This buffer's got modified and becoming part
1159 * of the transaction. This needs to be done
1160 * once a transaction -bzzz
1161 */
1162 jh->b_modified = 1;
1163 J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
1164 handle->h_buffer_credits--;
1165 }
1166
1167 /*
1168 * fastpath, to avoid expensive locking. If this buffer is already
1169 * on the running transaction's metadata list there is nothing to do.
1170 * Nobody can take it off again because there is a handle open.
1171 * I _think_ we're OK here with SMP barriers - a mistaken decision will
1172 * result in this test being false, so we go in and take the locks.
1173 */
1174 if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1175 JBUFFER_TRACE(jh, "fastpath");
1176 J_ASSERT_JH(jh, jh->b_transaction ==
1177 journal->j_running_transaction);
1178 goto out_unlock_bh;
1179 }
1180
1181 set_buffer_jbddirty(bh);
1182
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001183 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184 * Metadata already on the current transaction list doesn't
1185 * need to be filed. Metadata on another transaction's list must
1186 * be committing, and will be refiled once the commit completes:
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001187 * leave it alone for now.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188 */
1189 if (jh->b_transaction != transaction) {
1190 JBUFFER_TRACE(jh, "already on other transaction");
1191 J_ASSERT_JH(jh, jh->b_transaction ==
1192 journal->j_committing_transaction);
1193 J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
1194 /* And this case is illegal: we can't reuse another
1195 * transaction's data buffer, ever. */
1196 goto out_unlock_bh;
1197 }
1198
1199 /* That test should have eliminated the following case: */
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001200 J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201
1202 JBUFFER_TRACE(jh, "file as BJ_Metadata");
1203 spin_lock(&journal->j_list_lock);
1204 __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1205 spin_unlock(&journal->j_list_lock);
1206out_unlock_bh:
1207 jbd_unlock_bh_state(bh);
1208out:
1209 JBUFFER_TRACE(jh, "exit");
1210 return 0;
1211}
1212
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001213/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214 * journal_release_buffer: undo a get_write_access without any buffer
1215 * updates, if the update decided in the end that it didn't need access.
1216 *
1217 */
1218void
1219journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1220{
1221 BUFFER_TRACE(bh, "entry");
1222}
1223
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001224/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001225 * void journal_forget() - bforget() for potentially-journaled buffers.
1226 * @handle: transaction handle
1227 * @bh: bh to 'forget'
1228 *
1229 * We can only do the bforget if there are no commits pending against the
1230 * buffer. If the buffer is dirty in the current running transaction we
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001231 * can safely unlink it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001232 *
1233 * bh may not be a journalled buffer at all - it may be a non-JBD
1234 * buffer which came off the hashtable. Check for this.
1235 *
1236 * Decrements bh->b_count by one.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001237 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238 * Allow this call even if the handle has aborted --- it may be part of
1239 * the caller's cleanup after an abort.
1240 */
1241int journal_forget (handle_t *handle, struct buffer_head *bh)
1242{
1243 transaction_t *transaction = handle->h_transaction;
1244 journal_t *journal = transaction->t_journal;
1245 struct journal_head *jh;
1246 int drop_reserve = 0;
1247 int err = 0;
Josef Bacik5b9a4992008-04-28 02:16:12 -07001248 int was_modified = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249
1250 BUFFER_TRACE(bh, "entry");
1251
1252 jbd_lock_bh_state(bh);
1253 spin_lock(&journal->j_list_lock);
1254
1255 if (!buffer_jbd(bh))
1256 goto not_jbd;
1257 jh = bh2jh(bh);
1258
1259 /* Critical error: attempting to delete a bitmap buffer, maybe?
1260 * Don't do any jbd operations, and return an error. */
1261 if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1262 "inconsistent data on disk")) {
1263 err = -EIO;
1264 goto not_jbd;
1265 }
1266
Josef Bacik5b9a4992008-04-28 02:16:12 -07001267 /* keep track of wether or not this transaction modified us */
1268 was_modified = jh->b_modified;
1269
Linus Torvalds1da177e2005-04-16 15:20:36 -07001270 /*
1271 * The buffer's going from the transaction, we must drop
1272 * all references -bzzz
1273 */
1274 jh->b_modified = 0;
1275
1276 if (jh->b_transaction == handle->h_transaction) {
1277 J_ASSERT_JH(jh, !jh->b_frozen_data);
1278
1279 /* If we are forgetting a buffer which is already part
1280 * of this transaction, then we can just drop it from
1281 * the transaction immediately. */
1282 clear_buffer_dirty(bh);
1283 clear_buffer_jbddirty(bh);
1284
1285 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1286
Josef Bacik5b9a4992008-04-28 02:16:12 -07001287 /*
1288 * we only want to drop a reference if this transaction
1289 * modified the buffer
1290 */
1291 if (was_modified)
1292 drop_reserve = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001293
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001294 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295 * We are no longer going to journal this buffer.
1296 * However, the commit of this transaction is still
1297 * important to the buffer: the delete that we are now
1298 * processing might obsolete an old log entry, so by
1299 * committing, we can satisfy the buffer's checkpoint.
1300 *
1301 * So, if we have a checkpoint on the buffer, we should
1302 * now refile the buffer on our BJ_Forget list so that
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001303 * we know to remove the checkpoint after we commit.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001304 */
1305
1306 if (jh->b_cp_transaction) {
1307 __journal_temp_unlink_buffer(jh);
1308 __journal_file_buffer(jh, transaction, BJ_Forget);
1309 } else {
1310 __journal_unfile_buffer(jh);
1311 journal_remove_journal_head(bh);
1312 __brelse(bh);
1313 if (!buffer_jbd(bh)) {
1314 spin_unlock(&journal->j_list_lock);
1315 jbd_unlock_bh_state(bh);
1316 __bforget(bh);
1317 goto drop;
1318 }
1319 }
1320 } else if (jh->b_transaction) {
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001321 J_ASSERT_JH(jh, (jh->b_transaction ==
Linus Torvalds1da177e2005-04-16 15:20:36 -07001322 journal->j_committing_transaction));
1323 /* However, if the buffer is still owned by a prior
1324 * (committing) transaction, we can't drop it yet... */
1325 JBUFFER_TRACE(jh, "belongs to older transaction");
1326 /* ... but we CAN drop it from the new transaction if we
1327 * have also modified it since the original commit. */
1328
1329 if (jh->b_next_transaction) {
1330 J_ASSERT(jh->b_next_transaction == transaction);
1331 jh->b_next_transaction = NULL;
Josef Bacik5b9a4992008-04-28 02:16:12 -07001332
1333 /*
1334 * only drop a reference if this transaction modified
1335 * the buffer
1336 */
1337 if (was_modified)
1338 drop_reserve = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001339 }
1340 }
1341
1342not_jbd:
1343 spin_unlock(&journal->j_list_lock);
1344 jbd_unlock_bh_state(bh);
1345 __brelse(bh);
1346drop:
1347 if (drop_reserve) {
1348 /* no need to reserve log space for this block -bzzz */
1349 handle->h_buffer_credits++;
1350 }
1351 return err;
1352}
1353
1354/**
1355 * int journal_stop() - complete a transaction
1356 * @handle: tranaction to complete.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001357 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358 * All done for a particular handle.
1359 *
1360 * There is not much action needed here. We just return any remaining
1361 * buffer credits to the transaction and remove the handle. The only
1362 * complication is that we need to start a commit operation if the
1363 * filesystem is marked for synchronous update.
1364 *
1365 * journal_stop itself will not usually return an error, but it may
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001366 * do so in unusual circumstances. In particular, expect it to
Linus Torvalds1da177e2005-04-16 15:20:36 -07001367 * return -EIO if a journal_abort has been executed since the
1368 * transaction began.
1369 */
1370int journal_stop(handle_t *handle)
1371{
1372 transaction_t *transaction = handle->h_transaction;
1373 journal_t *journal = transaction->t_journal;
Josef Bacikf420d4d2009-01-07 18:07:24 -08001374 int err;
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001375 pid_t pid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377 J_ASSERT(journal_current_handle() == handle);
1378
1379 if (is_handle_aborted(handle))
1380 err = -EIO;
OGAWA Hirofumi3e2a5322006-10-19 23:29:11 -07001381 else {
1382 J_ASSERT(transaction->t_updates > 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 err = 0;
OGAWA Hirofumi3e2a5322006-10-19 23:29:11 -07001384 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385
1386 if (--handle->h_ref > 0) {
1387 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1388 handle->h_ref);
1389 return err;
1390 }
1391
1392 jbd_debug(4, "Handle %p going down\n", handle);
1393
1394 /*
1395 * Implement synchronous transaction batching. If the handle
1396 * was synchronous, don't force a commit immediately. Let's
1397 * yield and let another thread piggyback onto this transaction.
1398 * Keep doing that while new threads continue to arrive.
1399 * It doesn't cost much - we're about to run a commit and sleep
1400 * on IO anyway. Speeds up many-threaded, many-dir operations
1401 * by 30x or more...
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001402 *
Josef Bacikf420d4d2009-01-07 18:07:24 -08001403 * We try and optimize the sleep time against what the underlying disk
1404 * can do, instead of having a static sleep time. This is usefull for
1405 * the case where our storage is so fast that it is more optimal to go
1406 * ahead and force a flush and wait for the transaction to be committed
1407 * than it is to wait for an arbitrary amount of time for new writers to
1408 * join the transaction. We acheive this by measuring how long it takes
1409 * to commit a transaction, and compare it with how long this
1410 * transaction has been running, and if run time < commit time then we
1411 * sleep for the delta and commit. This greatly helps super fast disks
1412 * that would see slowdowns as more threads started doing fsyncs.
1413 *
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001414 * But don't do this if this process was the most recent one to
1415 * perform a synchronous write. We do this to detect the case where a
1416 * single process is doing a stream of sync writes. No point in waiting
1417 * for joiners in that case.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418 */
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001419 pid = current->pid;
1420 if (handle->h_sync && journal->j_last_sync_writer != pid) {
Josef Bacikf420d4d2009-01-07 18:07:24 -08001421 u64 commit_time, trans_time;
1422
Andrew Mortonfe1dcbc2006-02-04 23:27:54 -08001423 journal->j_last_sync_writer = pid;
Josef Bacikf420d4d2009-01-07 18:07:24 -08001424
1425 spin_lock(&journal->j_state_lock);
1426 commit_time = journal->j_average_commit_time;
1427 spin_unlock(&journal->j_state_lock);
1428
1429 trans_time = ktime_to_ns(ktime_sub(ktime_get(),
1430 transaction->t_start_time));
1431
1432 commit_time = min_t(u64, commit_time,
1433 1000*jiffies_to_usecs(1));
1434
1435 if (trans_time < commit_time) {
1436 ktime_t expires = ktime_add_ns(ktime_get(),
1437 commit_time);
1438 set_current_state(TASK_UNINTERRUPTIBLE);
1439 schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
1440 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441 }
1442
Theodore Ts'o512a0042009-03-27 22:14:27 -04001443 if (handle->h_sync)
1444 transaction->t_synchronous_commit = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445 current->journal_info = NULL;
1446 spin_lock(&journal->j_state_lock);
1447 spin_lock(&transaction->t_handle_lock);
1448 transaction->t_outstanding_credits -= handle->h_buffer_credits;
1449 transaction->t_updates--;
1450 if (!transaction->t_updates) {
1451 wake_up(&journal->j_wait_updates);
1452 if (journal->j_barrier_count)
1453 wake_up(&journal->j_wait_transaction_locked);
1454 }
1455
1456 /*
1457 * If the handle is marked SYNC, we need to set another commit
1458 * going! We also want to force a commit if the current
1459 * transaction is occupying too much of the log, or if the
1460 * transaction is too old now.
1461 */
1462 if (handle->h_sync ||
1463 transaction->t_outstanding_credits >
1464 journal->j_max_transaction_buffers ||
Dave Kleikampe9ad5622006-09-27 01:49:35 -07001465 time_after_eq(jiffies, transaction->t_expires)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466 /* Do this even for aborted journals: an abort still
1467 * completes the commit thread, it just doesn't write
1468 * anything to disk. */
1469 tid_t tid = transaction->t_tid;
1470
1471 spin_unlock(&transaction->t_handle_lock);
1472 jbd_debug(2, "transaction too old, requesting commit for "
1473 "handle %p\n", handle);
1474 /* This is non-blocking */
1475 __log_start_commit(journal, transaction->t_tid);
1476 spin_unlock(&journal->j_state_lock);
1477
1478 /*
1479 * Special case: JFS_SYNC synchronous updates require us
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001480 * to wait for the commit to complete.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001481 */
1482 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1483 err = log_wait_commit(journal, tid);
1484 } else {
1485 spin_unlock(&transaction->t_handle_lock);
1486 spin_unlock(&journal->j_state_lock);
1487 }
1488
Ingo Molnar3295f0e2008-08-11 10:30:30 +02001489 lock_map_release(&handle->h_lockdep_map);
Peter Zijlstra34a3d1e2007-10-11 22:11:12 +02001490
Linus Torvalds1da177e2005-04-16 15:20:36 -07001491 jbd_free_handle(handle);
1492 return err;
1493}
1494
Randy Dunlap0cf01f62008-03-19 17:00:44 -07001495/**
1496 * int journal_force_commit() - force any uncommitted transactions
Linus Torvalds1da177e2005-04-16 15:20:36 -07001497 * @journal: journal to force
1498 *
1499 * For synchronous operations: force any uncommitted transactions
1500 * to disk. May seem kludgy, but it reuses all the handle batching
1501 * code in a very simple manner.
1502 */
1503int journal_force_commit(journal_t *journal)
1504{
1505 handle_t *handle;
1506 int ret;
1507
1508 handle = journal_start(journal, 1);
1509 if (IS_ERR(handle)) {
1510 ret = PTR_ERR(handle);
1511 } else {
1512 handle->h_sync = 1;
1513 ret = journal_stop(handle);
1514 }
1515 return ret;
1516}
1517
1518/*
1519 *
1520 * List management code snippets: various functions for manipulating the
1521 * transaction buffer lists.
1522 *
1523 */
1524
1525/*
1526 * Append a buffer to a transaction list, given the transaction's list head
1527 * pointer.
1528 *
1529 * j_list_lock is held.
1530 *
1531 * jbd_lock_bh_state(jh2bh(jh)) is held.
1532 */
1533
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001534static inline void
Linus Torvalds1da177e2005-04-16 15:20:36 -07001535__blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1536{
1537 if (!*list) {
1538 jh->b_tnext = jh->b_tprev = jh;
1539 *list = jh;
1540 } else {
1541 /* Insert at the tail of the list to preserve order */
1542 struct journal_head *first = *list, *last = first->b_tprev;
1543 jh->b_tprev = last;
1544 jh->b_tnext = first;
1545 last->b_tnext = first->b_tprev = jh;
1546 }
1547}
1548
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001549/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001550 * Remove a buffer from a transaction list, given the transaction's list
1551 * head pointer.
1552 *
1553 * Called with j_list_lock held, and the journal may not be locked.
1554 *
1555 * jbd_lock_bh_state(jh2bh(jh)) is held.
1556 */
1557
1558static inline void
1559__blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1560{
1561 if (*list == jh) {
1562 *list = jh->b_tnext;
1563 if (*list == jh)
1564 *list = NULL;
1565 }
1566 jh->b_tprev->b_tnext = jh->b_tnext;
1567 jh->b_tnext->b_tprev = jh->b_tprev;
1568}
1569
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001570/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001571 * Remove a buffer from the appropriate transaction list.
1572 *
1573 * Note that this function can *change* the value of
1574 * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
1575 * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list. If the caller
1576 * is holding onto a copy of one of thee pointers, it could go bad.
1577 * Generally the caller needs to re-read the pointer from the transaction_t.
1578 *
1579 * Called under j_list_lock. The journal may not be locked.
1580 */
Adrian Bunkd394e122006-12-06 20:38:26 -08001581static void __journal_temp_unlink_buffer(struct journal_head *jh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001582{
1583 struct journal_head **list = NULL;
1584 transaction_t *transaction;
1585 struct buffer_head *bh = jh2bh(jh);
1586
1587 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1588 transaction = jh->b_transaction;
1589 if (transaction)
1590 assert_spin_locked(&transaction->t_journal->j_list_lock);
1591
1592 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1593 if (jh->b_jlist != BJ_None)
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001594 J_ASSERT_JH(jh, transaction != NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001595
1596 switch (jh->b_jlist) {
1597 case BJ_None:
1598 return;
1599 case BJ_SyncData:
1600 list = &transaction->t_sync_datalist;
1601 break;
1602 case BJ_Metadata:
1603 transaction->t_nr_buffers--;
1604 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1605 list = &transaction->t_buffers;
1606 break;
1607 case BJ_Forget:
1608 list = &transaction->t_forget;
1609 break;
1610 case BJ_IO:
1611 list = &transaction->t_iobuf_list;
1612 break;
1613 case BJ_Shadow:
1614 list = &transaction->t_shadow_list;
1615 break;
1616 case BJ_LogCtl:
1617 list = &transaction->t_log_list;
1618 break;
1619 case BJ_Reserved:
1620 list = &transaction->t_reserved_list;
1621 break;
1622 case BJ_Locked:
1623 list = &transaction->t_locked_list;
1624 break;
1625 }
1626
1627 __blist_del_buffer(list, jh);
1628 jh->b_jlist = BJ_None;
1629 if (test_clear_buffer_jbddirty(bh))
1630 mark_buffer_dirty(bh); /* Expose it to the VM */
1631}
1632
1633void __journal_unfile_buffer(struct journal_head *jh)
1634{
1635 __journal_temp_unlink_buffer(jh);
1636 jh->b_transaction = NULL;
1637}
1638
1639void journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1640{
1641 jbd_lock_bh_state(jh2bh(jh));
1642 spin_lock(&journal->j_list_lock);
1643 __journal_unfile_buffer(jh);
1644 spin_unlock(&journal->j_list_lock);
1645 jbd_unlock_bh_state(jh2bh(jh));
1646}
1647
1648/*
1649 * Called from journal_try_to_free_buffers().
1650 *
1651 * Called under jbd_lock_bh_state(bh)
1652 */
1653static void
1654__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1655{
1656 struct journal_head *jh;
1657
1658 jh = bh2jh(bh);
1659
1660 if (buffer_locked(bh) || buffer_dirty(bh))
1661 goto out;
1662
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001663 if (jh->b_next_transaction != NULL)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664 goto out;
1665
1666 spin_lock(&journal->j_list_lock);
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001667 if (jh->b_transaction != NULL && jh->b_cp_transaction == NULL) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001668 if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
1669 /* A written-back ordered data buffer */
1670 JBUFFER_TRACE(jh, "release data");
1671 __journal_unfile_buffer(jh);
1672 journal_remove_journal_head(bh);
1673 __brelse(bh);
1674 }
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07001675 } else if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001676 /* written-back checkpointed metadata buffer */
1677 if (jh->b_jlist == BJ_None) {
1678 JBUFFER_TRACE(jh, "remove from checkpoint list");
1679 __journal_remove_checkpoint(jh);
1680 journal_remove_journal_head(bh);
1681 __brelse(bh);
1682 }
1683 }
1684 spin_unlock(&journal->j_list_lock);
1685out:
1686 return;
1687}
1688
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001689/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001690 * int journal_try_to_free_buffers() - try to free page buffers.
1691 * @journal: journal for operation
1692 * @page: to try and free
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001693 * @gfp_mask: we use the mask to detect how hard should we try to release
1694 * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to
1695 * release the buffers.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696 *
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001697 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001698 * For all the buffers on this page,
1699 * if they are fully written out ordered data, move them onto BUF_CLEAN
1700 * so try_to_free_buffers() can reap them.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001701 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001702 * This function returns non-zero if we wish try_to_free_buffers()
1703 * to be called. We do this if the page is releasable by try_to_free_buffers().
1704 * We also do it if the page has locked or dirty buffers and the caller wants
1705 * us to perform sync or async writeout.
1706 *
1707 * This complicates JBD locking somewhat. We aren't protected by the
1708 * BKL here. We wish to remove the buffer from its committing or
1709 * running transaction's ->t_datalist via __journal_unfile_buffer.
1710 *
1711 * This may *change* the value of transaction_t->t_datalist, so anyone
1712 * who looks at t_datalist needs to lock against this function.
1713 *
1714 * Even worse, someone may be doing a journal_dirty_data on this
1715 * buffer. So we need to lock against that. journal_dirty_data()
1716 * will come out of the lock with the buffer dirty, which makes it
1717 * ineligible for release here.
1718 *
1719 * Who else is affected by this? hmm... Really the only contender
1720 * is do_get_write_access() - it could be looking at the buffer while
1721 * journal_try_to_free_buffer() is changing its state. But that
1722 * cannot happen because we never reallocate freed data as metadata
1723 * while the data is part of a transaction. Yes?
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001724 *
1725 * Return 0 on failure, 1 on success
Linus Torvalds1da177e2005-04-16 15:20:36 -07001726 */
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001727int journal_try_to_free_buffers(journal_t *journal,
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001728 struct page *page, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001729{
1730 struct buffer_head *head;
1731 struct buffer_head *bh;
1732 int ret = 0;
1733
1734 J_ASSERT(PageLocked(page));
1735
1736 head = page_buffers(page);
1737 bh = head;
1738 do {
1739 struct journal_head *jh;
1740
1741 /*
1742 * We take our own ref against the journal_head here to avoid
1743 * having to add tons of locking around each instance of
1744 * journal_remove_journal_head() and journal_put_journal_head().
1745 */
1746 jh = journal_grab_journal_head(bh);
1747 if (!jh)
1748 continue;
1749
1750 jbd_lock_bh_state(bh);
1751 __journal_try_to_free_buffer(journal, bh);
1752 journal_put_journal_head(jh);
1753 jbd_unlock_bh_state(bh);
1754 if (buffer_jbd(bh))
1755 goto busy;
1756 } while ((bh = bh->b_this_page) != head);
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001757
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758 ret = try_to_free_buffers(page);
Mingming Cao3f31fdd2008-07-25 01:46:22 -07001759
Linus Torvalds1da177e2005-04-16 15:20:36 -07001760busy:
1761 return ret;
1762}
1763
1764/*
1765 * This buffer is no longer needed. If it is on an older transaction's
1766 * checkpoint list we need to record it on this transaction's forget list
1767 * to pin this buffer (and hence its checkpointing transaction) down until
1768 * this transaction commits. If the buffer isn't on a checkpoint list, we
1769 * release it.
1770 * Returns non-zero if JBD no longer has an interest in the buffer.
1771 *
1772 * Called under j_list_lock.
1773 *
1774 * Called under jbd_lock_bh_state(bh).
1775 */
1776static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1777{
1778 int may_free = 1;
1779 struct buffer_head *bh = jh2bh(jh);
1780
1781 __journal_unfile_buffer(jh);
1782
1783 if (jh->b_cp_transaction) {
1784 JBUFFER_TRACE(jh, "on running+cp transaction");
1785 __journal_file_buffer(jh, transaction, BJ_Forget);
1786 clear_buffer_jbddirty(bh);
1787 may_free = 0;
1788 } else {
1789 JBUFFER_TRACE(jh, "on running transaction");
1790 journal_remove_journal_head(bh);
1791 __brelse(bh);
1792 }
1793 return may_free;
1794}
1795
1796/*
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001797 * journal_invalidatepage
Linus Torvalds1da177e2005-04-16 15:20:36 -07001798 *
1799 * This code is tricky. It has a number of cases to deal with.
1800 *
1801 * There are two invariants which this code relies on:
1802 *
1803 * i_size must be updated on disk before we start calling invalidatepage on the
1804 * data.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001805 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001806 * This is done in ext3 by defining an ext3_setattr method which
1807 * updates i_size before truncate gets going. By maintaining this
1808 * invariant, we can be sure that it is safe to throw away any buffers
1809 * attached to the current transaction: once the transaction commits,
1810 * we know that the data will not be needed.
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001811 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001812 * Note however that we can *not* throw away data belonging to the
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001813 * previous, committing transaction!
Linus Torvalds1da177e2005-04-16 15:20:36 -07001814 *
1815 * Any disk blocks which *are* part of the previous, committing
1816 * transaction (and which therefore cannot be discarded immediately) are
1817 * not going to be reused in the new running transaction
1818 *
1819 * The bitmap committed_data images guarantee this: any block which is
1820 * allocated in one transaction and removed in the next will be marked
1821 * as in-use in the committed_data bitmap, so cannot be reused until
1822 * the next transaction to delete the block commits. This means that
1823 * leaving committing buffers dirty is quite safe: the disk blocks
1824 * cannot be reallocated to a different file and so buffer aliasing is
1825 * not possible.
1826 *
1827 *
1828 * The above applies mainly to ordered data mode. In writeback mode we
1829 * don't make guarantees about the order in which data hits disk --- in
1830 * particular we don't guarantee that new dirty data is flushed before
1831 * transaction commit --- so it is always safe just to discard data
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001832 * immediately in that mode. --sct
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833 */
1834
1835/*
1836 * The journal_unmap_buffer helper function returns zero if the buffer
1837 * concerned remains pinned as an anonymous buffer belonging to an older
1838 * transaction.
1839 *
1840 * We're outside-transaction here. Either or both of j_running_transaction
1841 * and j_committing_transaction may be NULL.
1842 */
1843static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1844{
1845 transaction_t *transaction;
1846 struct journal_head *jh;
1847 int may_free = 1;
1848 int ret;
1849
1850 BUFFER_TRACE(bh, "entry");
1851
1852 /*
1853 * It is safe to proceed here without the j_list_lock because the
1854 * buffers cannot be stolen by try_to_free_buffers as long as we are
1855 * holding the page lock. --sct
1856 */
1857
1858 if (!buffer_jbd(bh))
1859 goto zap_buffer_unlocked;
1860
1861 spin_lock(&journal->j_state_lock);
1862 jbd_lock_bh_state(bh);
1863 spin_lock(&journal->j_list_lock);
1864
1865 jh = journal_grab_journal_head(bh);
1866 if (!jh)
1867 goto zap_buffer_no_jh;
1868
1869 transaction = jh->b_transaction;
1870 if (transaction == NULL) {
1871 /* First case: not on any transaction. If it
1872 * has no checkpoint link, then we can zap it:
1873 * it's a writeback-mode buffer so we don't care
1874 * if it hits disk safely. */
1875 if (!jh->b_cp_transaction) {
1876 JBUFFER_TRACE(jh, "not on any transaction: zap");
1877 goto zap_buffer;
1878 }
1879
1880 if (!buffer_dirty(bh)) {
1881 /* bdflush has written it. We can drop it now */
1882 goto zap_buffer;
1883 }
1884
1885 /* OK, it must be in the journal but still not
1886 * written fully to disk: it's metadata or
1887 * journaled data... */
1888
1889 if (journal->j_running_transaction) {
1890 /* ... and once the current transaction has
1891 * committed, the buffer won't be needed any
1892 * longer. */
1893 JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1894 ret = __dispose_buffer(jh,
1895 journal->j_running_transaction);
1896 journal_put_journal_head(jh);
1897 spin_unlock(&journal->j_list_lock);
1898 jbd_unlock_bh_state(bh);
1899 spin_unlock(&journal->j_state_lock);
1900 return ret;
1901 } else {
1902 /* There is no currently-running transaction. So the
1903 * orphan record which we wrote for this file must have
1904 * passed into commit. We must attach this buffer to
1905 * the committing transaction, if it exists. */
1906 if (journal->j_committing_transaction) {
1907 JBUFFER_TRACE(jh, "give to committing trans");
1908 ret = __dispose_buffer(jh,
1909 journal->j_committing_transaction);
1910 journal_put_journal_head(jh);
1911 spin_unlock(&journal->j_list_lock);
1912 jbd_unlock_bh_state(bh);
1913 spin_unlock(&journal->j_state_lock);
1914 return ret;
1915 } else {
1916 /* The orphan record's transaction has
1917 * committed. We can cleanse this buffer */
1918 clear_buffer_jbddirty(bh);
1919 goto zap_buffer;
1920 }
1921 }
1922 } else if (transaction == journal->j_committing_transaction) {
Eric Sandeenf58a74d2006-10-28 10:38:27 -07001923 JBUFFER_TRACE(jh, "on committing transaction");
akpm@osdl.orgd13df842005-04-16 15:26:36 -07001924 if (jh->b_jlist == BJ_Locked) {
1925 /*
1926 * The buffer is on the committing transaction's locked
1927 * list. We have the buffer locked, so I/O has
1928 * completed. So we can nail the buffer now.
1929 */
1930 may_free = __dispose_buffer(jh, transaction);
1931 goto zap_buffer;
1932 }
1933 /*
1934 * If it is committing, we simply cannot touch it. We
Linus Torvalds1da177e2005-04-16 15:20:36 -07001935 * can remove it's next_transaction pointer from the
1936 * running transaction if that is set, but nothing
1937 * else. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001938 set_buffer_freed(bh);
1939 if (jh->b_next_transaction) {
1940 J_ASSERT(jh->b_next_transaction ==
1941 journal->j_running_transaction);
1942 jh->b_next_transaction = NULL;
1943 }
1944 journal_put_journal_head(jh);
1945 spin_unlock(&journal->j_list_lock);
1946 jbd_unlock_bh_state(bh);
1947 spin_unlock(&journal->j_state_lock);
1948 return 0;
1949 } else {
1950 /* Good, the buffer belongs to the running transaction.
1951 * We are writing our own transaction's data, not any
1952 * previous one's, so it is safe to throw it away
1953 * (remember that we expect the filesystem to have set
1954 * i_size already for this truncate so recovery will not
1955 * expose the disk blocks we are discarding here.) */
1956 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
Eric Sandeenf58a74d2006-10-28 10:38:27 -07001957 JBUFFER_TRACE(jh, "on running transaction");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001958 may_free = __dispose_buffer(jh, transaction);
1959 }
1960
1961zap_buffer:
1962 journal_put_journal_head(jh);
1963zap_buffer_no_jh:
1964 spin_unlock(&journal->j_list_lock);
1965 jbd_unlock_bh_state(bh);
1966 spin_unlock(&journal->j_state_lock);
1967zap_buffer_unlocked:
1968 clear_buffer_dirty(bh);
1969 J_ASSERT_BH(bh, !buffer_jbddirty(bh));
1970 clear_buffer_mapped(bh);
1971 clear_buffer_req(bh);
1972 clear_buffer_new(bh);
1973 bh->b_bdev = NULL;
1974 return may_free;
1975}
1976
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001977/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07001978 * void journal_invalidatepage() - invalidate a journal page
1979 * @journal: journal to use for flush
Linus Torvalds1da177e2005-04-16 15:20:36 -07001980 * @page: page to flush
1981 * @offset: length of page to invalidate.
1982 *
1983 * Reap page buffers containing data after offset in page.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001984 */
NeilBrown2ff28e22006-03-26 01:37:18 -08001985void journal_invalidatepage(journal_t *journal,
Mingming Caoae6ddcc2006-09-27 01:49:27 -07001986 struct page *page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001987 unsigned long offset)
1988{
1989 struct buffer_head *head, *bh, *next;
1990 unsigned int curr_off = 0;
1991 int may_free = 1;
1992
1993 if (!PageLocked(page))
1994 BUG();
1995 if (!page_has_buffers(page))
NeilBrown2ff28e22006-03-26 01:37:18 -08001996 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001997
1998 /* We will potentially be playing with lists other than just the
1999 * data lists (especially for journaled data mode), so be
2000 * cautious in our locking. */
2001
2002 head = bh = page_buffers(page);
2003 do {
2004 unsigned int next_off = curr_off + bh->b_size;
2005 next = bh->b_this_page;
2006
Linus Torvalds1da177e2005-04-16 15:20:36 -07002007 if (offset <= curr_off) {
Dave Kleikampe9ad5622006-09-27 01:49:35 -07002008 /* This block is wholly outside the truncation point */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002009 lock_buffer(bh);
2010 may_free &= journal_unmap_buffer(journal, bh);
2011 unlock_buffer(bh);
2012 }
2013 curr_off = next_off;
2014 bh = next;
2015
2016 } while (bh != head);
2017
2018 if (!offset) {
NeilBrown2ff28e22006-03-26 01:37:18 -08002019 if (may_free && try_to_free_buffers(page))
2020 J_ASSERT(!page_has_buffers(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002021 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002022}
2023
Mingming Caoae6ddcc2006-09-27 01:49:27 -07002024/*
2025 * File a buffer on the given transaction list.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002026 */
2027void __journal_file_buffer(struct journal_head *jh,
2028 transaction_t *transaction, int jlist)
2029{
2030 struct journal_head **list = NULL;
2031 int was_dirty = 0;
2032 struct buffer_head *bh = jh2bh(jh);
2033
2034 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2035 assert_spin_locked(&transaction->t_journal->j_list_lock);
2036
2037 J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
2038 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
Stephen Hemmingerc80544d2007-10-18 03:07:05 -07002039 jh->b_transaction == NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002040
2041 if (jh->b_transaction && jh->b_jlist == jlist)
2042 return;
2043
2044 /* The following list of buffer states needs to be consistent
2045 * with __jbd_unexpected_dirty_buffer()'s handling of dirty
2046 * state. */
2047
Mingming Caoae6ddcc2006-09-27 01:49:27 -07002048 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07002049 jlist == BJ_Shadow || jlist == BJ_Forget) {
2050 if (test_clear_buffer_dirty(bh) ||
2051 test_clear_buffer_jbddirty(bh))
2052 was_dirty = 1;
2053 }
2054
2055 if (jh->b_transaction)
2056 __journal_temp_unlink_buffer(jh);
2057 jh->b_transaction = transaction;
2058
2059 switch (jlist) {
2060 case BJ_None:
2061 J_ASSERT_JH(jh, !jh->b_committed_data);
2062 J_ASSERT_JH(jh, !jh->b_frozen_data);
2063 return;
2064 case BJ_SyncData:
2065 list = &transaction->t_sync_datalist;
2066 break;
2067 case BJ_Metadata:
2068 transaction->t_nr_buffers++;
2069 list = &transaction->t_buffers;
2070 break;
2071 case BJ_Forget:
2072 list = &transaction->t_forget;
2073 break;
2074 case BJ_IO:
2075 list = &transaction->t_iobuf_list;
2076 break;
2077 case BJ_Shadow:
2078 list = &transaction->t_shadow_list;
2079 break;
2080 case BJ_LogCtl:
2081 list = &transaction->t_log_list;
2082 break;
2083 case BJ_Reserved:
2084 list = &transaction->t_reserved_list;
2085 break;
2086 case BJ_Locked:
2087 list = &transaction->t_locked_list;
2088 break;
2089 }
2090
2091 __blist_add_buffer(list, jh);
2092 jh->b_jlist = jlist;
2093
2094 if (was_dirty)
2095 set_buffer_jbddirty(bh);
2096}
2097
2098void journal_file_buffer(struct journal_head *jh,
2099 transaction_t *transaction, int jlist)
2100{
2101 jbd_lock_bh_state(jh2bh(jh));
2102 spin_lock(&transaction->t_journal->j_list_lock);
2103 __journal_file_buffer(jh, transaction, jlist);
2104 spin_unlock(&transaction->t_journal->j_list_lock);
2105 jbd_unlock_bh_state(jh2bh(jh));
2106}
2107
Mingming Caoae6ddcc2006-09-27 01:49:27 -07002108/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109 * Remove a buffer from its current buffer list in preparation for
2110 * dropping it from its current transaction entirely. If the buffer has
2111 * already started to be used by a subsequent transaction, refile the
2112 * buffer on that transaction's metadata list.
2113 *
2114 * Called under journal->j_list_lock
2115 *
2116 * Called under jbd_lock_bh_state(jh2bh(jh))
2117 */
2118void __journal_refile_buffer(struct journal_head *jh)
2119{
2120 int was_dirty;
2121 struct buffer_head *bh = jh2bh(jh);
2122
2123 J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2124 if (jh->b_transaction)
2125 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2126
2127 /* If the buffer is now unused, just drop it. */
2128 if (jh->b_next_transaction == NULL) {
2129 __journal_unfile_buffer(jh);
2130 return;
2131 }
2132
2133 /*
2134 * It has been modified by a later transaction: add it to the new
2135 * transaction's metadata list.
2136 */
2137
2138 was_dirty = test_clear_buffer_jbddirty(bh);
2139 __journal_temp_unlink_buffer(jh);
2140 jh->b_transaction = jh->b_next_transaction;
2141 jh->b_next_transaction = NULL;
Jan Kara9ada7342006-06-23 02:05:25 -07002142 __journal_file_buffer(jh, jh->b_transaction,
Josef Bacik5b9a4992008-04-28 02:16:12 -07002143 jh->b_modified ? BJ_Metadata : BJ_Reserved);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002144 J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2145
2146 if (was_dirty)
2147 set_buffer_jbddirty(bh);
2148}
2149
2150/*
2151 * For the unlocked version of this call, also make sure that any
2152 * hanging journal_head is cleaned up if necessary.
2153 *
2154 * __journal_refile_buffer is usually called as part of a single locked
2155 * operation on a buffer_head, in which the caller is probably going to
2156 * be hooking the journal_head onto other lists. In that case it is up
2157 * to the caller to remove the journal_head if necessary. For the
2158 * unlocked journal_refile_buffer call, the caller isn't going to be
2159 * doing anything else to the buffer so we need to do the cleanup
Mingming Caoae6ddcc2006-09-27 01:49:27 -07002160 * ourselves to avoid a jh leak.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002161 *
2162 * *** The journal_head may be freed by this call! ***
2163 */
2164void journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2165{
2166 struct buffer_head *bh = jh2bh(jh);
2167
2168 jbd_lock_bh_state(bh);
2169 spin_lock(&journal->j_list_lock);
2170
2171 __journal_refile_buffer(jh);
2172 jbd_unlock_bh_state(bh);
2173 journal_remove_journal_head(bh);
2174
2175 spin_unlock(&journal->j_list_lock);
2176 __brelse(bh);
2177}