jbd2: fix possible journal overflow issues
[linux-2.6.git] / fs / jbd2 / transaction.c
1 /*
2  * linux/fs/jbd2/transaction.c
3  *
4  * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
5  *
6  * Copyright 1998 Red Hat corp --- All Rights Reserved
7  *
8  * This file is part of the Linux kernel and is made available under
9  * the terms of the GNU General Public License, version 2, or at your
10  * option, any later version, incorporated herein by reference.
11  *
12  * Generic filesystem transaction handling code; part of the ext2fs
13  * journaling system.
14  *
15  * This file manages transactions (compound commits managed by the
16  * journaling code) and handles (individual atomic operations by the
17  * filesystem).
18  */
19
20 #include <linux/time.h>
21 #include <linux/fs.h>
22 #include <linux/jbd2.h>
23 #include <linux/errno.h>
24 #include <linux/slab.h>
25 #include <linux/timer.h>
26 #include <linux/mm.h>
27 #include <linux/highmem.h>
28
29 static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh);
30
31 /*
32  * jbd2_get_transaction: obtain a new transaction_t object.
33  *
34  * Simply allocate and initialise a new transaction.  Create it in
35  * RUNNING state and add it to the current journal (which should not
36  * have an existing running transaction: we only make a new transaction
37  * once we have started to commit the old one).
38  *
39  * Preconditions:
40  *      The journal MUST be locked.  We don't perform atomic mallocs on the
41  *      new transaction and we can't block without protecting against other
42  *      processes trying to touch the journal while it is in transition.
43  *
44  * Called under j_state_lock
45  */
46
47 static transaction_t *
48 jbd2_get_transaction(journal_t *journal, transaction_t *transaction)
49 {
50         transaction->t_journal = journal;
51         transaction->t_state = T_RUNNING;
52         transaction->t_tid = journal->j_transaction_sequence++;
53         transaction->t_expires = jiffies + journal->j_commit_interval;
54         spin_lock_init(&transaction->t_handle_lock);
55
56         /* Set up the commit timer for the new transaction. */
57         journal->j_commit_timer.expires = round_jiffies(transaction->t_expires);
58         add_timer(&journal->j_commit_timer);
59
60         J_ASSERT(journal->j_running_transaction == NULL);
61         journal->j_running_transaction = transaction;
62         transaction->t_max_wait = 0;
63         transaction->t_start = jiffies;
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
80  * transaction's buffer credits.
81  */
82
83 static 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         unsigned long ts = jiffies;
91
92         if (nblocks > journal->j_max_transaction_buffers) {
93                 printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
94                        current->comm, nblocks,
95                        journal->j_max_transaction_buffers);
96                 ret = -ENOSPC;
97                 goto out;
98         }
99
100 alloc_transaction:
101         if (!journal->j_running_transaction) {
102                 new_transaction = kzalloc(sizeof(*new_transaction),
103                                                 GFP_NOFS|__GFP_NOFAIL);
104                 if (!new_transaction) {
105                         ret = -ENOMEM;
106                         goto out;
107                 }
108         }
109
110         jbd_debug(3, "New handle %p going live.\n", handle);
111
112 repeat:
113
114         /*
115          * We need to hold j_state_lock until t_updates has been incremented,
116          * for proper journal barrier handling
117          */
118         spin_lock(&journal->j_state_lock);
119 repeat_locked:
120         if (is_journal_aborted(journal) ||
121             (journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) {
122                 spin_unlock(&journal->j_state_lock);
123                 ret = -EROFS;
124                 goto out;
125         }
126
127         /* Wait on the journal's transaction barrier if necessary */
128         if (journal->j_barrier_count) {
129                 spin_unlock(&journal->j_state_lock);
130                 wait_event(journal->j_wait_transaction_locked,
131                                 journal->j_barrier_count == 0);
132                 goto repeat;
133         }
134
135         if (!journal->j_running_transaction) {
136                 if (!new_transaction) {
137                         spin_unlock(&journal->j_state_lock);
138                         goto alloc_transaction;
139                 }
140                 jbd2_get_transaction(journal, new_transaction);
141                 new_transaction = NULL;
142         }
143
144         transaction = journal->j_running_transaction;
145
146         /*
147          * If the current transaction is locked down for commit, wait for the
148          * lock to be released.
149          */
150         if (transaction->t_state == T_LOCKED) {
151                 DEFINE_WAIT(wait);
152
153                 prepare_to_wait(&journal->j_wait_transaction_locked,
154                                         &wait, TASK_UNINTERRUPTIBLE);
155                 spin_unlock(&journal->j_state_lock);
156                 schedule();
157                 finish_wait(&journal->j_wait_transaction_locked, &wait);
158                 goto repeat;
159         }
160
161         /*
162          * If there is not enough space left in the log to write all potential
163          * buffers requested by this operation, we need to stall pending a log
164          * checkpoint to free some more log space.
165          */
166         spin_lock(&transaction->t_handle_lock);
167         needed = transaction->t_outstanding_credits + nblocks;
168
169         if (needed > journal->j_max_transaction_buffers) {
170                 /*
171                  * If the current transaction is already too large, then start
172                  * to commit it: we can then go back and attach this handle to
173                  * a new transaction.
174                  */
175                 DEFINE_WAIT(wait);
176
177                 jbd_debug(2, "Handle %p starting new commit...\n", handle);
178                 spin_unlock(&transaction->t_handle_lock);
179                 prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
180                                 TASK_UNINTERRUPTIBLE);
181                 __jbd2_log_start_commit(journal, transaction->t_tid);
182                 spin_unlock(&journal->j_state_lock);
183                 schedule();
184                 finish_wait(&journal->j_wait_transaction_locked, &wait);
185                 goto repeat;
186         }
187
188         /*
189          * The commit code assumes that it can get enough log space
190          * without forcing a checkpoint.  This is *critical* for
191          * correctness: a checkpoint of a buffer which is also
192          * associated with a committing transaction creates a deadlock,
193          * so commit simply cannot force through checkpoints.
194          *
195          * We must therefore ensure the necessary space in the journal
196          * *before* starting to dirty potentially checkpointed buffers
197          * in the new transaction.
198          *
199          * The worst part is, any transaction currently committing can
200          * reduce the free space arbitrarily.  Be careful to account for
201          * those buffers when checkpointing.
202          */
203
204         /*
205          * @@@ AKPM: This seems rather over-defensive.  We're giving commit
206          * a _lot_ of headroom: 1/4 of the journal plus the size of
207          * the committing transaction.  Really, we only need to give it
208          * committing_transaction->t_outstanding_credits plus "enough" for
209          * the log control blocks.
210          * Also, this test is inconsitent with the matching one in
211          * jbd2_journal_extend().
212          */
213         if (__jbd2_log_space_left(journal) < jbd_space_needed(journal)) {
214                 jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
215                 spin_unlock(&transaction->t_handle_lock);
216                 __jbd2_log_wait_for_space(journal);
217                 goto repeat_locked;
218         }
219
220         /* OK, account for the buffers that this operation expects to
221          * use and add the handle to the running transaction. */
222
223         if (time_after(transaction->t_start, ts)) {
224                 ts = jbd2_time_diff(ts, transaction->t_start);
225                 if (ts > transaction->t_max_wait)
226                         transaction->t_max_wait = ts;
227         }
228
229         handle->h_transaction = transaction;
230         transaction->t_outstanding_credits += nblocks;
231         transaction->t_updates++;
232         transaction->t_handle_count++;
233         jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
234                   handle, nblocks, transaction->t_outstanding_credits,
235                   __jbd2_log_space_left(journal));
236         spin_unlock(&transaction->t_handle_lock);
237         spin_unlock(&journal->j_state_lock);
238 out:
239         if (unlikely(new_transaction))          /* It's usually NULL */
240                 kfree(new_transaction);
241         return ret;
242 }
243
244 static struct lock_class_key jbd2_handle_key;
245
246 /* Allocate a new handle.  This should probably be in a slab... */
247 static handle_t *new_handle(int nblocks)
248 {
249         handle_t *handle = jbd2_alloc_handle(GFP_NOFS);
250         if (!handle)
251                 return NULL;
252         memset(handle, 0, sizeof(*handle));
253         handle->h_buffer_credits = nblocks;
254         handle->h_ref = 1;
255
256         lockdep_init_map(&handle->h_lockdep_map, "jbd2_handle",
257                                                 &jbd2_handle_key, 0);
258
259         return handle;
260 }
261
262 /**
263  * handle_t *jbd2_journal_start() - Obtain a new handle.
264  * @journal: Journal to start transaction on.
265  * @nblocks: number of block buffer we might modify
266  *
267  * We make sure that the transaction can guarantee at least nblocks of
268  * modified buffers in the log.  We block until the log can guarantee
269  * that much space.
270  *
271  * This function is visible to journal users (like ext3fs), so is not
272  * called with the journal already locked.
273  *
274  * Return a pointer to a newly allocated handle, or NULL on failure
275  */
276 handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
277 {
278         handle_t *handle = journal_current_handle();
279         int err;
280
281         if (!journal)
282                 return ERR_PTR(-EROFS);
283
284         if (handle) {
285                 J_ASSERT(handle->h_transaction->t_journal == journal);
286                 handle->h_ref++;
287                 return handle;
288         }
289
290         handle = new_handle(nblocks);
291         if (!handle)
292                 return ERR_PTR(-ENOMEM);
293
294         current->journal_info = handle;
295
296         err = start_this_handle(journal, handle);
297         if (err < 0) {
298                 jbd2_free_handle(handle);
299                 current->journal_info = NULL;
300                 handle = ERR_PTR(err);
301                 goto out;
302         }
303
304         lock_acquire(&handle->h_lockdep_map, 0, 0, 0, 2, _THIS_IP_);
305 out:
306         return handle;
307 }
308
309 /**
310  * int jbd2_journal_extend() - extend buffer credits.
311  * @handle:  handle to 'extend'
312  * @nblocks: nr blocks to try to extend by.
313  *
314  * Some transactions, such as large extends and truncates, can be done
315  * atomically all at once or in several stages.  The operation requests
316  * a credit for a number of buffer modications in advance, but can
317  * extend its credit if it needs more.
318  *
319  * jbd2_journal_extend tries to give the running handle more buffer credits.
320  * It does not guarantee that allocation - this is a best-effort only.
321  * The calling process MUST be able to deal cleanly with a failure to
322  * extend here.
323  *
324  * Return 0 on success, non-zero on failure.
325  *
326  * return code < 0 implies an error
327  * return code > 0 implies normal transaction-full status.
328  */
329 int jbd2_journal_extend(handle_t *handle, int nblocks)
330 {
331         transaction_t *transaction = handle->h_transaction;
332         journal_t *journal = transaction->t_journal;
333         int result;
334         int wanted;
335
336         result = -EIO;
337         if (is_handle_aborted(handle))
338                 goto out;
339
340         result = 1;
341
342         spin_lock(&journal->j_state_lock);
343
344         /* Don't extend a locked-down transaction! */
345         if (handle->h_transaction->t_state != T_RUNNING) {
346                 jbd_debug(3, "denied handle %p %d blocks: "
347                           "transaction not running\n", handle, nblocks);
348                 goto error_out;
349         }
350
351         spin_lock(&transaction->t_handle_lock);
352         wanted = transaction->t_outstanding_credits + nblocks;
353
354         if (wanted > journal->j_max_transaction_buffers) {
355                 jbd_debug(3, "denied handle %p %d blocks: "
356                           "transaction too large\n", handle, nblocks);
357                 goto unlock;
358         }
359
360         if (wanted > __jbd2_log_space_left(journal)) {
361                 jbd_debug(3, "denied handle %p %d blocks: "
362                           "insufficient log space\n", handle, nblocks);
363                 goto unlock;
364         }
365
366         handle->h_buffer_credits += nblocks;
367         transaction->t_outstanding_credits += nblocks;
368         result = 0;
369
370         jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
371 unlock:
372         spin_unlock(&transaction->t_handle_lock);
373 error_out:
374         spin_unlock(&journal->j_state_lock);
375 out:
376         return result;
377 }
378
379
380 /**
381  * int jbd2_journal_restart() - restart a handle .
382  * @handle:  handle to restart
383  * @nblocks: nr credits requested
384  *
385  * Restart a handle for a multi-transaction filesystem
386  * operation.
387  *
388  * If the jbd2_journal_extend() call above fails to grant new buffer credits
389  * to a running handle, a call to jbd2_journal_restart will commit the
390  * handle's transaction so far and reattach the handle to a new
391  * transaction capabable of guaranteeing the requested number of
392  * credits.
393  */
394
395 int jbd2_journal_restart(handle_t *handle, int nblocks)
396 {
397         transaction_t *transaction = handle->h_transaction;
398         journal_t *journal = transaction->t_journal;
399         int ret;
400
401         /* If we've had an abort of any type, don't even think about
402          * actually doing the restart! */
403         if (is_handle_aborted(handle))
404                 return 0;
405
406         /*
407          * First unlink the handle from its current transaction, and start the
408          * commit on that.
409          */
410         J_ASSERT(transaction->t_updates > 0);
411         J_ASSERT(journal_current_handle() == handle);
412
413         spin_lock(&journal->j_state_lock);
414         spin_lock(&transaction->t_handle_lock);
415         transaction->t_outstanding_credits -= handle->h_buffer_credits;
416         transaction->t_updates--;
417
418         if (!transaction->t_updates)
419                 wake_up(&journal->j_wait_updates);
420         spin_unlock(&transaction->t_handle_lock);
421
422         jbd_debug(2, "restarting handle %p\n", handle);
423         __jbd2_log_start_commit(journal, transaction->t_tid);
424         spin_unlock(&journal->j_state_lock);
425
426         handle->h_buffer_credits = nblocks;
427         ret = start_this_handle(journal, handle);
428         return ret;
429 }
430
431
432 /**
433  * void jbd2_journal_lock_updates () - establish a transaction barrier.
434  * @journal:  Journal to establish a barrier on.
435  *
436  * This locks out any further updates from being started, and blocks
437  * until all existing updates have completed, returning only once the
438  * journal is in a quiescent state with no updates running.
439  *
440  * The journal lock should not be held on entry.
441  */
442 void jbd2_journal_lock_updates(journal_t *journal)
443 {
444         DEFINE_WAIT(wait);
445
446         spin_lock(&journal->j_state_lock);
447         ++journal->j_barrier_count;
448
449         /* Wait until there are no running updates */
450         while (1) {
451                 transaction_t *transaction = journal->j_running_transaction;
452
453                 if (!transaction)
454                         break;
455
456                 spin_lock(&transaction->t_handle_lock);
457                 if (!transaction->t_updates) {
458                         spin_unlock(&transaction->t_handle_lock);
459                         break;
460                 }
461                 prepare_to_wait(&journal->j_wait_updates, &wait,
462                                 TASK_UNINTERRUPTIBLE);
463                 spin_unlock(&transaction->t_handle_lock);
464                 spin_unlock(&journal->j_state_lock);
465                 schedule();
466                 finish_wait(&journal->j_wait_updates, &wait);
467                 spin_lock(&journal->j_state_lock);
468         }
469         spin_unlock(&journal->j_state_lock);
470
471         /*
472          * We have now established a barrier against other normal updates, but
473          * we also need to barrier against other jbd2_journal_lock_updates() calls
474          * to make sure that we serialise special journal-locked operations
475          * too.
476          */
477         mutex_lock(&journal->j_barrier);
478 }
479
480 /**
481  * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier
482  * @journal:  Journal to release the barrier on.
483  *
484  * Release a transaction barrier obtained with jbd2_journal_lock_updates().
485  *
486  * Should be called without the journal lock held.
487  */
488 void jbd2_journal_unlock_updates (journal_t *journal)
489 {
490         J_ASSERT(journal->j_barrier_count != 0);
491
492         mutex_unlock(&journal->j_barrier);
493         spin_lock(&journal->j_state_lock);
494         --journal->j_barrier_count;
495         spin_unlock(&journal->j_state_lock);
496         wake_up(&journal->j_wait_transaction_locked);
497 }
498
499 /*
500  * Report any unexpected dirty buffers which turn up.  Normally those
501  * indicate an error, but they can occur if the user is running (say)
502  * tune2fs to modify the live filesystem, so we need the option of
503  * continuing as gracefully as possible.  #
504  *
505  * The caller should already hold the journal lock and
506  * j_list_lock spinlock: most callers will need those anyway
507  * in order to probe the buffer's journaling state safely.
508  */
509 static void jbd_unexpected_dirty_buffer(struct journal_head *jh)
510 {
511         int jlist;
512
513         /* If this buffer is one which might reasonably be dirty
514          * --- ie. data, or not part of this journal --- then
515          * we're OK to leave it alone, but otherwise we need to
516          * move the dirty bit to the journal's own internal
517          * JBDDirty bit. */
518         jlist = jh->b_jlist;
519
520         if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
521             jlist == BJ_Shadow || jlist == BJ_Forget) {
522                 struct buffer_head *bh = jh2bh(jh);
523
524                 if (test_clear_buffer_dirty(bh))
525                         set_buffer_jbddirty(bh);
526         }
527 }
528
529 /*
530  * If the buffer is already part of the current transaction, then there
531  * is nothing we need to do.  If it is already part of a prior
532  * transaction which we are still committing to disk, then we need to
533  * make sure that we do not overwrite the old copy: we do copy-out to
534  * preserve the copy going to disk.  We also account the buffer against
535  * the handle's metadata buffer credits (unless the buffer is already
536  * part of the transaction, that is).
537  *
538  */
539 static int
540 do_get_write_access(handle_t *handle, struct journal_head *jh,
541                         int force_copy)
542 {
543         struct buffer_head *bh;
544         transaction_t *transaction;
545         journal_t *journal;
546         int error;
547         char *frozen_buffer = NULL;
548         int need_copy = 0;
549
550         if (is_handle_aborted(handle))
551                 return -EROFS;
552
553         transaction = handle->h_transaction;
554         journal = transaction->t_journal;
555
556         jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy);
557
558         JBUFFER_TRACE(jh, "entry");
559 repeat:
560         bh = jh2bh(jh);
561
562         /* @@@ Need to check for errors here at some point. */
563
564         lock_buffer(bh);
565         jbd_lock_bh_state(bh);
566
567         /* We now hold the buffer lock so it is safe to query the buffer
568          * state.  Is the buffer dirty?
569          *
570          * If so, there are two possibilities.  The buffer may be
571          * non-journaled, and undergoing a quite legitimate writeback.
572          * Otherwise, it is journaled, and we don't expect dirty buffers
573          * in that state (the buffers should be marked JBD_Dirty
574          * instead.)  So either the IO is being done under our own
575          * control and this is a bug, or it's a third party IO such as
576          * dump(8) (which may leave the buffer scheduled for read ---
577          * ie. locked but not dirty) or tune2fs (which may actually have
578          * the buffer dirtied, ugh.)  */
579
580         if (buffer_dirty(bh)) {
581                 /*
582                  * First question: is this buffer already part of the current
583                  * transaction or the existing committing transaction?
584                  */
585                 if (jh->b_transaction) {
586                         J_ASSERT_JH(jh,
587                                 jh->b_transaction == transaction ||
588                                 jh->b_transaction ==
589                                         journal->j_committing_transaction);
590                         if (jh->b_next_transaction)
591                                 J_ASSERT_JH(jh, jh->b_next_transaction ==
592                                                         transaction);
593                 }
594                 /*
595                  * In any case we need to clean the dirty flag and we must
596                  * do it under the buffer lock to be sure we don't race
597                  * with running write-out.
598                  */
599                 JBUFFER_TRACE(jh, "Unexpected dirty buffer");
600                 jbd_unexpected_dirty_buffer(jh);
601         }
602
603         unlock_buffer(bh);
604
605         error = -EROFS;
606         if (is_handle_aborted(handle)) {
607                 jbd_unlock_bh_state(bh);
608                 goto out;
609         }
610         error = 0;
611
612         /*
613          * The buffer is already part of this transaction if b_transaction or
614          * b_next_transaction points to it
615          */
616         if (jh->b_transaction == transaction ||
617             jh->b_next_transaction == transaction)
618                 goto done;
619
620         /*
621          * this is the first time this transaction is touching this buffer,
622          * reset the modified flag
623          */
624        jh->b_modified = 0;
625
626         /*
627          * If there is already a copy-out version of this buffer, then we don't
628          * need to make another one
629          */
630         if (jh->b_frozen_data) {
631                 JBUFFER_TRACE(jh, "has frozen data");
632                 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
633                 jh->b_next_transaction = transaction;
634                 goto done;
635         }
636
637         /* Is there data here we need to preserve? */
638
639         if (jh->b_transaction && jh->b_transaction != transaction) {
640                 JBUFFER_TRACE(jh, "owned by older transaction");
641                 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
642                 J_ASSERT_JH(jh, jh->b_transaction ==
643                                         journal->j_committing_transaction);
644
645                 /* There is one case we have to be very careful about.
646                  * If the committing transaction is currently writing
647                  * this buffer out to disk and has NOT made a copy-out,
648                  * then we cannot modify the buffer contents at all
649                  * right now.  The essence of copy-out is that it is the
650                  * extra copy, not the primary copy, which gets
651                  * journaled.  If the primary copy is already going to
652                  * disk then we cannot do copy-out here. */
653
654                 if (jh->b_jlist == BJ_Shadow) {
655                         DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
656                         wait_queue_head_t *wqh;
657
658                         wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
659
660                         JBUFFER_TRACE(jh, "on shadow: sleep");
661                         jbd_unlock_bh_state(bh);
662                         /* commit wakes up all shadow buffers after IO */
663                         for ( ; ; ) {
664                                 prepare_to_wait(wqh, &wait.wait,
665                                                 TASK_UNINTERRUPTIBLE);
666                                 if (jh->b_jlist != BJ_Shadow)
667                                         break;
668                                 schedule();
669                         }
670                         finish_wait(wqh, &wait.wait);
671                         goto repeat;
672                 }
673
674                 /* Only do the copy if the currently-owning transaction
675                  * still needs it.  If it is on the Forget list, the
676                  * committing transaction is past that stage.  The
677                  * buffer had better remain locked during the kmalloc,
678                  * but that should be true --- we hold the journal lock
679                  * still and the buffer is already on the BUF_JOURNAL
680                  * list so won't be flushed.
681                  *
682                  * Subtle point, though: if this is a get_undo_access,
683                  * then we will be relying on the frozen_data to contain
684                  * the new value of the committed_data record after the
685                  * transaction, so we HAVE to force the frozen_data copy
686                  * in that case. */
687
688                 if (jh->b_jlist != BJ_Forget || force_copy) {
689                         JBUFFER_TRACE(jh, "generate frozen data");
690                         if (!frozen_buffer) {
691                                 JBUFFER_TRACE(jh, "allocate memory for buffer");
692                                 jbd_unlock_bh_state(bh);
693                                 frozen_buffer =
694                                         jbd2_alloc(jh2bh(jh)->b_size,
695                                                          GFP_NOFS);
696                                 if (!frozen_buffer) {
697                                         printk(KERN_EMERG
698                                                "%s: OOM for frozen_buffer\n",
699                                                __FUNCTION__);
700                                         JBUFFER_TRACE(jh, "oom!");
701                                         error = -ENOMEM;
702                                         jbd_lock_bh_state(bh);
703                                         goto done;
704                                 }
705                                 goto repeat;
706                         }
707                         jh->b_frozen_data = frozen_buffer;
708                         frozen_buffer = NULL;
709                         need_copy = 1;
710                 }
711                 jh->b_next_transaction = transaction;
712         }
713
714
715         /*
716          * Finally, if the buffer is not journaled right now, we need to make
717          * sure it doesn't get written to disk before the caller actually
718          * commits the new data
719          */
720         if (!jh->b_transaction) {
721                 JBUFFER_TRACE(jh, "no transaction");
722                 J_ASSERT_JH(jh, !jh->b_next_transaction);
723                 jh->b_transaction = transaction;
724                 JBUFFER_TRACE(jh, "file as BJ_Reserved");
725                 spin_lock(&journal->j_list_lock);
726                 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
727                 spin_unlock(&journal->j_list_lock);
728         }
729
730 done:
731         if (need_copy) {
732                 struct page *page;
733                 int offset;
734                 char *source;
735
736                 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
737                             "Possible IO failure.\n");
738                 page = jh2bh(jh)->b_page;
739                 offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK;
740                 source = kmap_atomic(page, KM_USER0);
741                 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
742                 kunmap_atomic(source, KM_USER0);
743         }
744         jbd_unlock_bh_state(bh);
745
746         /*
747          * If we are about to journal a buffer, then any revoke pending on it is
748          * no longer valid
749          */
750         jbd2_journal_cancel_revoke(handle, jh);
751
752 out:
753         if (unlikely(frozen_buffer))    /* It's usually NULL */
754                 jbd2_free(frozen_buffer, bh->b_size);
755
756         JBUFFER_TRACE(jh, "exit");
757         return error;
758 }
759
760 /**
761  * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
762  * @handle: transaction to add buffer modifications to
763  * @bh:     bh to be used for metadata writes
764  * @credits: variable that will receive credits for the buffer
765  *
766  * Returns an error code or 0 on success.
767  *
768  * In full data journalling mode the buffer may be of type BJ_AsyncData,
769  * because we're write()ing a buffer which is also part of a shared mapping.
770  */
771
772 int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
773 {
774         struct journal_head *jh = jbd2_journal_add_journal_head(bh);
775         int rc;
776
777         /* We do not want to get caught playing with fields which the
778          * log thread also manipulates.  Make sure that the buffer
779          * completes any outstanding IO before proceeding. */
780         rc = do_get_write_access(handle, jh, 0);
781         jbd2_journal_put_journal_head(jh);
782         return rc;
783 }
784
785
786 /*
787  * When the user wants to journal a newly created buffer_head
788  * (ie. getblk() returned a new buffer and we are going to populate it
789  * manually rather than reading off disk), then we need to keep the
790  * buffer_head locked until it has been completely filled with new
791  * data.  In this case, we should be able to make the assertion that
792  * the bh is not already part of an existing transaction.
793  *
794  * The buffer should already be locked by the caller by this point.
795  * There is no lock ranking violation: it was a newly created,
796  * unlocked buffer beforehand. */
797
798 /**
799  * int jbd2_journal_get_create_access () - notify intent to use newly created bh
800  * @handle: transaction to new buffer to
801  * @bh: new buffer.
802  *
803  * Call this if you create a new bh.
804  */
805 int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
806 {
807         transaction_t *transaction = handle->h_transaction;
808         journal_t *journal = transaction->t_journal;
809         struct journal_head *jh = jbd2_journal_add_journal_head(bh);
810         int err;
811
812         jbd_debug(5, "journal_head %p\n", jh);
813         err = -EROFS;
814         if (is_handle_aborted(handle))
815                 goto out;
816         err = 0;
817
818         JBUFFER_TRACE(jh, "entry");
819         /*
820          * The buffer may already belong to this transaction due to pre-zeroing
821          * in the filesystem's new_block code.  It may also be on the previous,
822          * committing transaction's lists, but it HAS to be in Forget state in
823          * that case: the transaction must have deleted the buffer for it to be
824          * reused here.
825          */
826         jbd_lock_bh_state(bh);
827         spin_lock(&journal->j_list_lock);
828         J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
829                 jh->b_transaction == NULL ||
830                 (jh->b_transaction == journal->j_committing_transaction &&
831                           jh->b_jlist == BJ_Forget)));
832
833         J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
834         J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
835
836         if (jh->b_transaction == NULL) {
837                 jh->b_transaction = transaction;
838
839                 /* first access by this transaction */
840                 jh->b_modified = 0;
841
842                 JBUFFER_TRACE(jh, "file as BJ_Reserved");
843                 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
844         } else if (jh->b_transaction == journal->j_committing_transaction) {
845                 /* first access by this transaction */
846                 jh->b_modified = 0;
847
848                 JBUFFER_TRACE(jh, "set next transaction");
849                 jh->b_next_transaction = transaction;
850         }
851         spin_unlock(&journal->j_list_lock);
852         jbd_unlock_bh_state(bh);
853
854         /*
855          * akpm: I added this.  ext3_alloc_branch can pick up new indirect
856          * blocks which contain freed but then revoked metadata.  We need
857          * to cancel the revoke in case we end up freeing it yet again
858          * and the reallocating as data - this would cause a second revoke,
859          * which hits an assertion error.
860          */
861         JBUFFER_TRACE(jh, "cancelling revoke");
862         jbd2_journal_cancel_revoke(handle, jh);
863         jbd2_journal_put_journal_head(jh);
864 out:
865         return err;
866 }
867
868 /**
869  * int jbd2_journal_get_undo_access() -  Notify intent to modify metadata with
870  *     non-rewindable consequences
871  * @handle: transaction
872  * @bh: buffer to undo
873  * @credits: store the number of taken credits here (if not NULL)
874  *
875  * Sometimes there is a need to distinguish between metadata which has
876  * been committed to disk and that which has not.  The ext3fs code uses
877  * this for freeing and allocating space, we have to make sure that we
878  * do not reuse freed space until the deallocation has been committed,
879  * since if we overwrote that space we would make the delete
880  * un-rewindable in case of a crash.
881  *
882  * To deal with that, jbd2_journal_get_undo_access requests write access to a
883  * buffer for parts of non-rewindable operations such as delete
884  * operations on the bitmaps.  The journaling code must keep a copy of
885  * the buffer's contents prior to the undo_access call until such time
886  * as we know that the buffer has definitely been committed to disk.
887  *
888  * We never need to know which transaction the committed data is part
889  * of, buffers touched here are guaranteed to be dirtied later and so
890  * will be committed to a new transaction in due course, at which point
891  * we can discard the old committed data pointer.
892  *
893  * Returns error number or 0 on success.
894  */
895 int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
896 {
897         int err;
898         struct journal_head *jh = jbd2_journal_add_journal_head(bh);
899         char *committed_data = NULL;
900
901         JBUFFER_TRACE(jh, "entry");
902
903         /*
904          * Do this first --- it can drop the journal lock, so we want to
905          * make sure that obtaining the committed_data is done
906          * atomically wrt. completion of any outstanding commits.
907          */
908         err = do_get_write_access(handle, jh, 1);
909         if (err)
910                 goto out;
911
912 repeat:
913         if (!jh->b_committed_data) {
914                 committed_data = jbd2_alloc(jh2bh(jh)->b_size, GFP_NOFS);
915                 if (!committed_data) {
916                         printk(KERN_EMERG "%s: No memory for committed data\n",
917                                 __FUNCTION__);
918                         err = -ENOMEM;
919                         goto out;
920                 }
921         }
922
923         jbd_lock_bh_state(bh);
924         if (!jh->b_committed_data) {
925                 /* Copy out the current buffer contents into the
926                  * preserved, committed copy. */
927                 JBUFFER_TRACE(jh, "generate b_committed data");
928                 if (!committed_data) {
929                         jbd_unlock_bh_state(bh);
930                         goto repeat;
931                 }
932
933                 jh->b_committed_data = committed_data;
934                 committed_data = NULL;
935                 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
936         }
937         jbd_unlock_bh_state(bh);
938 out:
939         jbd2_journal_put_journal_head(jh);
940         if (unlikely(committed_data))
941                 jbd2_free(committed_data, bh->b_size);
942         return err;
943 }
944
945 /**
946  * int jbd2_journal_dirty_data() -  mark a buffer as containing dirty data which
947  *                             needs to be flushed before we can commit the
948  *                             current transaction.
949  * @handle: transaction
950  * @bh: bufferhead to mark
951  *
952  * The buffer is placed on the transaction's data list and is marked as
953  * belonging to the transaction.
954  *
955  * Returns error number or 0 on success.
956  *
957  * jbd2_journal_dirty_data() can be called via page_launder->ext3_writepage
958  * by kswapd.
959  */
960 int jbd2_journal_dirty_data(handle_t *handle, struct buffer_head *bh)
961 {
962         journal_t *journal = handle->h_transaction->t_journal;
963         int need_brelse = 0;
964         struct journal_head *jh;
965
966         if (is_handle_aborted(handle))
967                 return 0;
968
969         jh = jbd2_journal_add_journal_head(bh);
970         JBUFFER_TRACE(jh, "entry");
971
972         /*
973          * The buffer could *already* be dirty.  Writeout can start
974          * at any time.
975          */
976         jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
977
978         /*
979          * What if the buffer is already part of a running transaction?
980          *
981          * There are two cases:
982          * 1) It is part of the current running transaction.  Refile it,
983          *    just in case we have allocated it as metadata, deallocated
984          *    it, then reallocated it as data.
985          * 2) It is part of the previous, still-committing transaction.
986          *    If all we want to do is to guarantee that the buffer will be
987          *    written to disk before this new transaction commits, then
988          *    being sure that the *previous* transaction has this same
989          *    property is sufficient for us!  Just leave it on its old
990          *    transaction.
991          *
992          * In case (2), the buffer must not already exist as metadata
993          * --- that would violate write ordering (a transaction is free
994          * to write its data at any point, even before the previous
995          * committing transaction has committed).  The caller must
996          * never, ever allow this to happen: there's nothing we can do
997          * about it in this layer.
998          */
999         jbd_lock_bh_state(bh);
1000         spin_lock(&journal->j_list_lock);
1001
1002         /* Now that we have bh_state locked, are we really still mapped? */
1003         if (!buffer_mapped(bh)) {
1004                 JBUFFER_TRACE(jh, "unmapped buffer, bailing out");
1005                 goto no_journal;
1006         }
1007
1008         if (jh->b_transaction) {
1009                 JBUFFER_TRACE(jh, "has transaction");
1010                 if (jh->b_transaction != handle->h_transaction) {
1011                         JBUFFER_TRACE(jh, "belongs to older transaction");
1012                         J_ASSERT_JH(jh, jh->b_transaction ==
1013                                         journal->j_committing_transaction);
1014
1015                         /* @@@ IS THIS TRUE  ? */
1016                         /*
1017                          * Not any more.  Scenario: someone does a write()
1018                          * in data=journal mode.  The buffer's transaction has
1019                          * moved into commit.  Then someone does another
1020                          * write() to the file.  We do the frozen data copyout
1021                          * and set b_next_transaction to point to j_running_t.
1022                          * And while we're in that state, someone does a
1023                          * writepage() in an attempt to pageout the same area
1024                          * of the file via a shared mapping.  At present that
1025                          * calls jbd2_journal_dirty_data(), and we get right here.
1026                          * It may be too late to journal the data.  Simply
1027                          * falling through to the next test will suffice: the
1028                          * data will be dirty and wil be checkpointed.  The
1029                          * ordering comments in the next comment block still
1030                          * apply.
1031                          */
1032                         //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1033
1034                         /*
1035                          * If we're journalling data, and this buffer was
1036                          * subject to a write(), it could be metadata, forget
1037                          * or shadow against the committing transaction.  Now,
1038                          * someone has dirtied the same darn page via a mapping
1039                          * and it is being writepage()'d.
1040                          * We *could* just steal the page from commit, with some
1041                          * fancy locking there.  Instead, we just skip it -
1042                          * don't tie the page's buffers to the new transaction
1043                          * at all.
1044                          * Implication: if we crash before the writepage() data
1045                          * is written into the filesystem, recovery will replay
1046                          * the write() data.
1047                          */
1048                         if (jh->b_jlist != BJ_None &&
1049                                         jh->b_jlist != BJ_SyncData &&
1050                                         jh->b_jlist != BJ_Locked) {
1051                                 JBUFFER_TRACE(jh, "Not stealing");
1052                                 goto no_journal;
1053                         }
1054
1055                         /*
1056                          * This buffer may be undergoing writeout in commit.  We
1057                          * can't return from here and let the caller dirty it
1058                          * again because that can cause the write-out loop in
1059                          * commit to never terminate.
1060                          */
1061                         if (buffer_dirty(bh)) {
1062                                 get_bh(bh);
1063                                 spin_unlock(&journal->j_list_lock);
1064                                 jbd_unlock_bh_state(bh);
1065                                 need_brelse = 1;
1066                                 sync_dirty_buffer(bh);
1067                                 jbd_lock_bh_state(bh);
1068                                 spin_lock(&journal->j_list_lock);
1069                                 /* Since we dropped the lock... */
1070                                 if (!buffer_mapped(bh)) {
1071                                         JBUFFER_TRACE(jh, "buffer got unmapped");
1072                                         goto no_journal;
1073                                 }
1074                                 /* The buffer may become locked again at any
1075                                    time if it is redirtied */
1076                         }
1077
1078                         /* journal_clean_data_list() may have got there first */
1079                         if (jh->b_transaction != NULL) {
1080                                 JBUFFER_TRACE(jh, "unfile from commit");
1081                                 __jbd2_journal_temp_unlink_buffer(jh);
1082                                 /* It still points to the committing
1083                                  * transaction; move it to this one so
1084                                  * that the refile assert checks are
1085                                  * happy. */
1086                                 jh->b_transaction = handle->h_transaction;
1087                         }
1088                         /* The buffer will be refiled below */
1089
1090                 }
1091                 /*
1092                  * Special case --- the buffer might actually have been
1093                  * allocated and then immediately deallocated in the previous,
1094                  * committing transaction, so might still be left on that
1095                  * transaction's metadata lists.
1096                  */
1097                 if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
1098                         JBUFFER_TRACE(jh, "not on correct data list: unfile");
1099                         J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
1100                         __jbd2_journal_temp_unlink_buffer(jh);
1101                         jh->b_transaction = handle->h_transaction;
1102                         JBUFFER_TRACE(jh, "file as data");
1103                         __jbd2_journal_file_buffer(jh, handle->h_transaction,
1104                                                 BJ_SyncData);
1105                 }
1106         } else {
1107                 JBUFFER_TRACE(jh, "not on a transaction");
1108                 __jbd2_journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
1109         }
1110 no_journal:
1111         spin_unlock(&journal->j_list_lock);
1112         jbd_unlock_bh_state(bh);
1113         if (need_brelse) {
1114                 BUFFER_TRACE(bh, "brelse");
1115                 __brelse(bh);
1116         }
1117         JBUFFER_TRACE(jh, "exit");
1118         jbd2_journal_put_journal_head(jh);
1119         return 0;
1120 }
1121
1122 /**
1123  * int jbd2_journal_dirty_metadata() -  mark a buffer as containing dirty metadata
1124  * @handle: transaction to add buffer to.
1125  * @bh: buffer to mark
1126  *
1127  * mark dirty metadata which needs to be journaled as part of the current
1128  * transaction.
1129  *
1130  * The buffer is placed on the transaction's metadata list and is marked
1131  * as belonging to the transaction.
1132  *
1133  * Returns error number or 0 on success.
1134  *
1135  * Special care needs to be taken if the buffer already belongs to the
1136  * current committing transaction (in which case we should have frozen
1137  * data present for that commit).  In that case, we don't relink the
1138  * buffer: that only gets done when the old transaction finally
1139  * completes its commit.
1140  */
1141 int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1142 {
1143         transaction_t *transaction = handle->h_transaction;
1144         journal_t *journal = transaction->t_journal;
1145         struct journal_head *jh = bh2jh(bh);
1146
1147         jbd_debug(5, "journal_head %p\n", jh);
1148         JBUFFER_TRACE(jh, "entry");
1149         if (is_handle_aborted(handle))
1150                 goto out;
1151
1152         jbd_lock_bh_state(bh);
1153
1154         if (jh->b_modified == 0) {
1155                 /*
1156                  * This buffer's got modified and becoming part
1157                  * of the transaction. This needs to be done
1158                  * once a transaction -bzzz
1159                  */
1160                 jh->b_modified = 1;
1161                 J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
1162                 handle->h_buffer_credits--;
1163         }
1164
1165         /*
1166          * fastpath, to avoid expensive locking.  If this buffer is already
1167          * on the running transaction's metadata list there is nothing to do.
1168          * Nobody can take it off again because there is a handle open.
1169          * I _think_ we're OK here with SMP barriers - a mistaken decision will
1170          * result in this test being false, so we go in and take the locks.
1171          */
1172         if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1173                 JBUFFER_TRACE(jh, "fastpath");
1174                 J_ASSERT_JH(jh, jh->b_transaction ==
1175                                         journal->j_running_transaction);
1176                 goto out_unlock_bh;
1177         }
1178
1179         set_buffer_jbddirty(bh);
1180
1181         /*
1182          * Metadata already on the current transaction list doesn't
1183          * need to be filed.  Metadata on another transaction's list must
1184          * be committing, and will be refiled once the commit completes:
1185          * leave it alone for now.
1186          */
1187         if (jh->b_transaction != transaction) {
1188                 JBUFFER_TRACE(jh, "already on other transaction");
1189                 J_ASSERT_JH(jh, jh->b_transaction ==
1190                                         journal->j_committing_transaction);
1191                 J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
1192                 /* And this case is illegal: we can't reuse another
1193                  * transaction's data buffer, ever. */
1194                 goto out_unlock_bh;
1195         }
1196
1197         /* That test should have eliminated the following case: */
1198         J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
1199
1200         JBUFFER_TRACE(jh, "file as BJ_Metadata");
1201         spin_lock(&journal->j_list_lock);
1202         __jbd2_journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1203         spin_unlock(&journal->j_list_lock);
1204 out_unlock_bh:
1205         jbd_unlock_bh_state(bh);
1206 out:
1207         JBUFFER_TRACE(jh, "exit");
1208         return 0;
1209 }
1210
1211 /*
1212  * jbd2_journal_release_buffer: undo a get_write_access without any buffer
1213  * updates, if the update decided in the end that it didn't need access.
1214  *
1215  */
1216 void
1217 jbd2_journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1218 {
1219         BUFFER_TRACE(bh, "entry");
1220 }
1221
1222 /**
1223  * void jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1224  * @handle: transaction handle
1225  * @bh:     bh to 'forget'
1226  *
1227  * We can only do the bforget if there are no commits pending against the
1228  * buffer.  If the buffer is dirty in the current running transaction we
1229  * can safely unlink it.
1230  *
1231  * bh may not be a journalled buffer at all - it may be a non-JBD
1232  * buffer which came off the hashtable.  Check for this.
1233  *
1234  * Decrements bh->b_count by one.
1235  *
1236  * Allow this call even if the handle has aborted --- it may be part of
1237  * the caller's cleanup after an abort.
1238  */
1239 int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh)
1240 {
1241         transaction_t *transaction = handle->h_transaction;
1242         journal_t *journal = transaction->t_journal;
1243         struct journal_head *jh;
1244         int drop_reserve = 0;
1245         int err = 0;
1246         int was_modified = 0;
1247
1248         BUFFER_TRACE(bh, "entry");
1249
1250         jbd_lock_bh_state(bh);
1251         spin_lock(&journal->j_list_lock);
1252
1253         if (!buffer_jbd(bh))
1254                 goto not_jbd;
1255         jh = bh2jh(bh);
1256
1257         /* Critical error: attempting to delete a bitmap buffer, maybe?
1258          * Don't do any jbd operations, and return an error. */
1259         if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1260                          "inconsistent data on disk")) {
1261                 err = -EIO;
1262                 goto not_jbd;
1263         }
1264
1265         /* keep track of wether or not this transaction modified us */
1266         was_modified = jh->b_modified;
1267
1268         /*
1269          * The buffer's going from the transaction, we must drop
1270          * all references -bzzz
1271          */
1272         jh->b_modified = 0;
1273
1274         if (jh->b_transaction == handle->h_transaction) {
1275                 J_ASSERT_JH(jh, !jh->b_frozen_data);
1276
1277                 /* If we are forgetting a buffer which is already part
1278                  * of this transaction, then we can just drop it from
1279                  * the transaction immediately. */
1280                 clear_buffer_dirty(bh);
1281                 clear_buffer_jbddirty(bh);
1282
1283                 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1284
1285                 /*
1286                  * we only want to drop a reference if this transaction
1287                  * modified the buffer
1288                  */
1289                 if (was_modified)
1290                         drop_reserve = 1;
1291
1292                 /*
1293                  * We are no longer going to journal this buffer.
1294                  * However, the commit of this transaction is still
1295                  * important to the buffer: the delete that we are now
1296                  * processing might obsolete an old log entry, so by
1297                  * committing, we can satisfy the buffer's checkpoint.
1298                  *
1299                  * So, if we have a checkpoint on the buffer, we should
1300                  * now refile the buffer on our BJ_Forget list so that
1301                  * we know to remove the checkpoint after we commit.
1302                  */
1303
1304                 if (jh->b_cp_transaction) {
1305                         __jbd2_journal_temp_unlink_buffer(jh);
1306                         __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1307                 } else {
1308                         __jbd2_journal_unfile_buffer(jh);
1309                         jbd2_journal_remove_journal_head(bh);
1310                         __brelse(bh);
1311                         if (!buffer_jbd(bh)) {
1312                                 spin_unlock(&journal->j_list_lock);
1313                                 jbd_unlock_bh_state(bh);
1314                                 __bforget(bh);
1315                                 goto drop;
1316                         }
1317                 }
1318         } else if (jh->b_transaction) {
1319                 J_ASSERT_JH(jh, (jh->b_transaction ==
1320                                  journal->j_committing_transaction));
1321                 /* However, if the buffer is still owned by a prior
1322                  * (committing) transaction, we can't drop it yet... */
1323                 JBUFFER_TRACE(jh, "belongs to older transaction");
1324                 /* ... but we CAN drop it from the new transaction if we
1325                  * have also modified it since the original commit. */
1326
1327                 if (jh->b_next_transaction) {
1328                         J_ASSERT(jh->b_next_transaction == transaction);
1329                         jh->b_next_transaction = NULL;
1330
1331                         /*
1332                          * only drop a reference if this transaction modified
1333                          * the buffer
1334                          */
1335                         if (was_modified)
1336                                 drop_reserve = 1;
1337                 }
1338         }
1339
1340 not_jbd:
1341         spin_unlock(&journal->j_list_lock);
1342         jbd_unlock_bh_state(bh);
1343         __brelse(bh);
1344 drop:
1345         if (drop_reserve) {
1346                 /* no need to reserve log space for this block -bzzz */
1347                 handle->h_buffer_credits++;
1348         }
1349         return err;
1350 }
1351
1352 /**
1353  * int jbd2_journal_stop() - complete a transaction
1354  * @handle: tranaction to complete.
1355  *
1356  * All done for a particular handle.
1357  *
1358  * There is not much action needed here.  We just return any remaining
1359  * buffer credits to the transaction and remove the handle.  The only
1360  * complication is that we need to start a commit operation if the
1361  * filesystem is marked for synchronous update.
1362  *
1363  * jbd2_journal_stop itself will not usually return an error, but it may
1364  * do so in unusual circumstances.  In particular, expect it to
1365  * return -EIO if a jbd2_journal_abort has been executed since the
1366  * transaction began.
1367  */
1368 int jbd2_journal_stop(handle_t *handle)
1369 {
1370         transaction_t *transaction = handle->h_transaction;
1371         journal_t *journal = transaction->t_journal;
1372         int old_handle_count, err;
1373         pid_t pid;
1374
1375         J_ASSERT(journal_current_handle() == handle);
1376
1377         if (is_handle_aborted(handle))
1378                 err = -EIO;
1379         else {
1380                 J_ASSERT(transaction->t_updates > 0);
1381                 err = 0;
1382         }
1383
1384         if (--handle->h_ref > 0) {
1385                 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1386                           handle->h_ref);
1387                 return err;
1388         }
1389
1390         jbd_debug(4, "Handle %p going down\n", handle);
1391
1392         /*
1393          * Implement synchronous transaction batching.  If the handle
1394          * was synchronous, don't force a commit immediately.  Let's
1395          * yield and let another thread piggyback onto this transaction.
1396          * Keep doing that while new threads continue to arrive.
1397          * It doesn't cost much - we're about to run a commit and sleep
1398          * on IO anyway.  Speeds up many-threaded, many-dir operations
1399          * by 30x or more...
1400          *
1401          * But don't do this if this process was the most recent one to
1402          * perform a synchronous write.  We do this to detect the case where a
1403          * single process is doing a stream of sync writes.  No point in waiting
1404          * for joiners in that case.
1405          */
1406         pid = current->pid;
1407         if (handle->h_sync && journal->j_last_sync_writer != pid) {
1408                 journal->j_last_sync_writer = pid;
1409                 do {
1410                         old_handle_count = transaction->t_handle_count;
1411                         schedule_timeout_uninterruptible(1);
1412                 } while (old_handle_count != transaction->t_handle_count);
1413         }
1414
1415         current->journal_info = NULL;
1416         spin_lock(&journal->j_state_lock);
1417         spin_lock(&transaction->t_handle_lock);
1418         transaction->t_outstanding_credits -= handle->h_buffer_credits;
1419         transaction->t_updates--;
1420         if (!transaction->t_updates) {
1421                 wake_up(&journal->j_wait_updates);
1422                 if (journal->j_barrier_count)
1423                         wake_up(&journal->j_wait_transaction_locked);
1424         }
1425
1426         /*
1427          * If the handle is marked SYNC, we need to set another commit
1428          * going!  We also want to force a commit if the current
1429          * transaction is occupying too much of the log, or if the
1430          * transaction is too old now.
1431          */
1432         if (handle->h_sync ||
1433                         transaction->t_outstanding_credits >
1434                                 journal->j_max_transaction_buffers ||
1435                         time_after_eq(jiffies, transaction->t_expires)) {
1436                 /* Do this even for aborted journals: an abort still
1437                  * completes the commit thread, it just doesn't write
1438                  * anything to disk. */
1439                 tid_t tid = transaction->t_tid;
1440
1441                 spin_unlock(&transaction->t_handle_lock);
1442                 jbd_debug(2, "transaction too old, requesting commit for "
1443                                         "handle %p\n", handle);
1444                 /* This is non-blocking */
1445                 __jbd2_log_start_commit(journal, transaction->t_tid);
1446                 spin_unlock(&journal->j_state_lock);
1447
1448                 /*
1449                  * Special case: JBD2_SYNC synchronous updates require us
1450                  * to wait for the commit to complete.
1451                  */
1452                 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1453                         err = jbd2_log_wait_commit(journal, tid);
1454         } else {
1455                 spin_unlock(&transaction->t_handle_lock);
1456                 spin_unlock(&journal->j_state_lock);
1457         }
1458
1459         lock_release(&handle->h_lockdep_map, 1, _THIS_IP_);
1460
1461         jbd2_free_handle(handle);
1462         return err;
1463 }
1464
1465 /**int jbd2_journal_force_commit() - force any uncommitted transactions
1466  * @journal: journal to force
1467  *
1468  * For synchronous operations: force any uncommitted transactions
1469  * to disk.  May seem kludgy, but it reuses all the handle batching
1470  * code in a very simple manner.
1471  */
1472 int jbd2_journal_force_commit(journal_t *journal)
1473 {
1474         handle_t *handle;
1475         int ret;
1476
1477         handle = jbd2_journal_start(journal, 1);
1478         if (IS_ERR(handle)) {
1479                 ret = PTR_ERR(handle);
1480         } else {
1481                 handle->h_sync = 1;
1482                 ret = jbd2_journal_stop(handle);
1483         }
1484         return ret;
1485 }
1486
1487 /*
1488  *
1489  * List management code snippets: various functions for manipulating the
1490  * transaction buffer lists.
1491  *
1492  */
1493
1494 /*
1495  * Append a buffer to a transaction list, given the transaction's list head
1496  * pointer.
1497  *
1498  * j_list_lock is held.
1499  *
1500  * jbd_lock_bh_state(jh2bh(jh)) is held.
1501  */
1502
1503 static inline void
1504 __blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1505 {
1506         if (!*list) {
1507                 jh->b_tnext = jh->b_tprev = jh;
1508                 *list = jh;
1509         } else {
1510                 /* Insert at the tail of the list to preserve order */
1511                 struct journal_head *first = *list, *last = first->b_tprev;
1512                 jh->b_tprev = last;
1513                 jh->b_tnext = first;
1514                 last->b_tnext = first->b_tprev = jh;
1515         }
1516 }
1517
1518 /*
1519  * Remove a buffer from a transaction list, given the transaction's list
1520  * head pointer.
1521  *
1522  * Called with j_list_lock held, and the journal may not be locked.
1523  *
1524  * jbd_lock_bh_state(jh2bh(jh)) is held.
1525  */
1526
1527 static inline void
1528 __blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1529 {
1530         if (*list == jh) {
1531                 *list = jh->b_tnext;
1532                 if (*list == jh)
1533                         *list = NULL;
1534         }
1535         jh->b_tprev->b_tnext = jh->b_tnext;
1536         jh->b_tnext->b_tprev = jh->b_tprev;
1537 }
1538
1539 /*
1540  * Remove a buffer from the appropriate transaction list.
1541  *
1542  * Note that this function can *change* the value of
1543  * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
1544  * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list.  If the caller
1545  * is holding onto a copy of one of thee pointers, it could go bad.
1546  * Generally the caller needs to re-read the pointer from the transaction_t.
1547  *
1548  * Called under j_list_lock.  The journal may not be locked.
1549  */
1550 void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
1551 {
1552         struct journal_head **list = NULL;
1553         transaction_t *transaction;
1554         struct buffer_head *bh = jh2bh(jh);
1555
1556         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1557         transaction = jh->b_transaction;
1558         if (transaction)
1559                 assert_spin_locked(&transaction->t_journal->j_list_lock);
1560
1561         J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1562         if (jh->b_jlist != BJ_None)
1563                 J_ASSERT_JH(jh, transaction != NULL);
1564
1565         switch (jh->b_jlist) {
1566         case BJ_None:
1567                 return;
1568         case BJ_SyncData:
1569                 list = &transaction->t_sync_datalist;
1570                 break;
1571         case BJ_Metadata:
1572                 transaction->t_nr_buffers--;
1573                 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1574                 list = &transaction->t_buffers;
1575                 break;
1576         case BJ_Forget:
1577                 list = &transaction->t_forget;
1578                 break;
1579         case BJ_IO:
1580                 list = &transaction->t_iobuf_list;
1581                 break;
1582         case BJ_Shadow:
1583                 list = &transaction->t_shadow_list;
1584                 break;
1585         case BJ_LogCtl:
1586                 list = &transaction->t_log_list;
1587                 break;
1588         case BJ_Reserved:
1589                 list = &transaction->t_reserved_list;
1590                 break;
1591         case BJ_Locked:
1592                 list = &transaction->t_locked_list;
1593                 break;
1594         }
1595
1596         __blist_del_buffer(list, jh);
1597         jh->b_jlist = BJ_None;
1598         if (test_clear_buffer_jbddirty(bh))
1599                 mark_buffer_dirty(bh);  /* Expose it to the VM */
1600 }
1601
1602 void __jbd2_journal_unfile_buffer(struct journal_head *jh)
1603 {
1604         __jbd2_journal_temp_unlink_buffer(jh);
1605         jh->b_transaction = NULL;
1606 }
1607
1608 void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1609 {
1610         jbd_lock_bh_state(jh2bh(jh));
1611         spin_lock(&journal->j_list_lock);
1612         __jbd2_journal_unfile_buffer(jh);
1613         spin_unlock(&journal->j_list_lock);
1614         jbd_unlock_bh_state(jh2bh(jh));
1615 }
1616
1617 /*
1618  * Called from jbd2_journal_try_to_free_buffers().
1619  *
1620  * Called under jbd_lock_bh_state(bh)
1621  */
1622 static void
1623 __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1624 {
1625         struct journal_head *jh;
1626
1627         jh = bh2jh(bh);
1628
1629         if (buffer_locked(bh) || buffer_dirty(bh))
1630                 goto out;
1631
1632         if (jh->b_next_transaction != NULL)
1633                 goto out;
1634
1635         spin_lock(&journal->j_list_lock);
1636         if (jh->b_transaction != NULL && jh->b_cp_transaction == NULL) {
1637                 if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
1638                         /* A written-back ordered data buffer */
1639                         JBUFFER_TRACE(jh, "release data");
1640                         __jbd2_journal_unfile_buffer(jh);
1641                         jbd2_journal_remove_journal_head(bh);
1642                         __brelse(bh);
1643                 }
1644         } else if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) {
1645                 /* written-back checkpointed metadata buffer */
1646                 if (jh->b_jlist == BJ_None) {
1647                         JBUFFER_TRACE(jh, "remove from checkpoint list");
1648                         __jbd2_journal_remove_checkpoint(jh);
1649                         jbd2_journal_remove_journal_head(bh);
1650                         __brelse(bh);
1651                 }
1652         }
1653         spin_unlock(&journal->j_list_lock);
1654 out:
1655         return;
1656 }
1657
1658
1659 /**
1660  * int jbd2_journal_try_to_free_buffers() - try to free page buffers.
1661  * @journal: journal for operation
1662  * @page: to try and free
1663  * @unused_gfp_mask: unused
1664  *
1665  *
1666  * For all the buffers on this page,
1667  * if they are fully written out ordered data, move them onto BUF_CLEAN
1668  * so try_to_free_buffers() can reap them.
1669  *
1670  * This function returns non-zero if we wish try_to_free_buffers()
1671  * to be called. We do this if the page is releasable by try_to_free_buffers().
1672  * We also do it if the page has locked or dirty buffers and the caller wants
1673  * us to perform sync or async writeout.
1674  *
1675  * This complicates JBD locking somewhat.  We aren't protected by the
1676  * BKL here.  We wish to remove the buffer from its committing or
1677  * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
1678  *
1679  * This may *change* the value of transaction_t->t_datalist, so anyone
1680  * who looks at t_datalist needs to lock against this function.
1681  *
1682  * Even worse, someone may be doing a jbd2_journal_dirty_data on this
1683  * buffer.  So we need to lock against that.  jbd2_journal_dirty_data()
1684  * will come out of the lock with the buffer dirty, which makes it
1685  * ineligible for release here.
1686  *
1687  * Who else is affected by this?  hmm...  Really the only contender
1688  * is do_get_write_access() - it could be looking at the buffer while
1689  * journal_try_to_free_buffer() is changing its state.  But that
1690  * cannot happen because we never reallocate freed data as metadata
1691  * while the data is part of a transaction.  Yes?
1692  */
1693 int jbd2_journal_try_to_free_buffers(journal_t *journal,
1694                                 struct page *page, gfp_t unused_gfp_mask)
1695 {
1696         struct buffer_head *head;
1697         struct buffer_head *bh;
1698         int ret = 0;
1699
1700         J_ASSERT(PageLocked(page));
1701
1702         head = page_buffers(page);
1703         bh = head;
1704         do {
1705                 struct journal_head *jh;
1706
1707                 /*
1708                  * We take our own ref against the journal_head here to avoid
1709                  * having to add tons of locking around each instance of
1710                  * jbd2_journal_remove_journal_head() and jbd2_journal_put_journal_head().
1711                  */
1712                 jh = jbd2_journal_grab_journal_head(bh);
1713                 if (!jh)
1714                         continue;
1715
1716                 jbd_lock_bh_state(bh);
1717                 __journal_try_to_free_buffer(journal, bh);
1718                 jbd2_journal_put_journal_head(jh);
1719                 jbd_unlock_bh_state(bh);
1720                 if (buffer_jbd(bh))
1721                         goto busy;
1722         } while ((bh = bh->b_this_page) != head);
1723         ret = try_to_free_buffers(page);
1724 busy:
1725         return ret;
1726 }
1727
1728 /*
1729  * This buffer is no longer needed.  If it is on an older transaction's
1730  * checkpoint list we need to record it on this transaction's forget list
1731  * to pin this buffer (and hence its checkpointing transaction) down until
1732  * this transaction commits.  If the buffer isn't on a checkpoint list, we
1733  * release it.
1734  * Returns non-zero if JBD no longer has an interest in the buffer.
1735  *
1736  * Called under j_list_lock.
1737  *
1738  * Called under jbd_lock_bh_state(bh).
1739  */
1740 static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1741 {
1742         int may_free = 1;
1743         struct buffer_head *bh = jh2bh(jh);
1744
1745         __jbd2_journal_unfile_buffer(jh);
1746
1747         if (jh->b_cp_transaction) {
1748                 JBUFFER_TRACE(jh, "on running+cp transaction");
1749                 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1750                 clear_buffer_jbddirty(bh);
1751                 may_free = 0;
1752         } else {
1753                 JBUFFER_TRACE(jh, "on running transaction");
1754                 jbd2_journal_remove_journal_head(bh);
1755                 __brelse(bh);
1756         }
1757         return may_free;
1758 }
1759
1760 /*
1761  * jbd2_journal_invalidatepage
1762  *
1763  * This code is tricky.  It has a number of cases to deal with.
1764  *
1765  * There are two invariants which this code relies on:
1766  *
1767  * i_size must be updated on disk before we start calling invalidatepage on the
1768  * data.
1769  *
1770  *  This is done in ext3 by defining an ext3_setattr method which
1771  *  updates i_size before truncate gets going.  By maintaining this
1772  *  invariant, we can be sure that it is safe to throw away any buffers
1773  *  attached to the current transaction: once the transaction commits,
1774  *  we know that the data will not be needed.
1775  *
1776  *  Note however that we can *not* throw away data belonging to the
1777  *  previous, committing transaction!
1778  *
1779  * Any disk blocks which *are* part of the previous, committing
1780  * transaction (and which therefore cannot be discarded immediately) are
1781  * not going to be reused in the new running transaction
1782  *
1783  *  The bitmap committed_data images guarantee this: any block which is
1784  *  allocated in one transaction and removed in the next will be marked
1785  *  as in-use in the committed_data bitmap, so cannot be reused until
1786  *  the next transaction to delete the block commits.  This means that
1787  *  leaving committing buffers dirty is quite safe: the disk blocks
1788  *  cannot be reallocated to a different file and so buffer aliasing is
1789  *  not possible.
1790  *
1791  *
1792  * The above applies mainly to ordered data mode.  In writeback mode we
1793  * don't make guarantees about the order in which data hits disk --- in
1794  * particular we don't guarantee that new dirty data is flushed before
1795  * transaction commit --- so it is always safe just to discard data
1796  * immediately in that mode.  --sct
1797  */
1798
1799 /*
1800  * The journal_unmap_buffer helper function returns zero if the buffer
1801  * concerned remains pinned as an anonymous buffer belonging to an older
1802  * transaction.
1803  *
1804  * We're outside-transaction here.  Either or both of j_running_transaction
1805  * and j_committing_transaction may be NULL.
1806  */
1807 static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1808 {
1809         transaction_t *transaction;
1810         struct journal_head *jh;
1811         int may_free = 1;
1812         int ret;
1813
1814         BUFFER_TRACE(bh, "entry");
1815
1816         /*
1817          * It is safe to proceed here without the j_list_lock because the
1818          * buffers cannot be stolen by try_to_free_buffers as long as we are
1819          * holding the page lock. --sct
1820          */
1821
1822         if (!buffer_jbd(bh))
1823                 goto zap_buffer_unlocked;
1824
1825         spin_lock(&journal->j_state_lock);
1826         jbd_lock_bh_state(bh);
1827         spin_lock(&journal->j_list_lock);
1828
1829         jh = jbd2_journal_grab_journal_head(bh);
1830         if (!jh)
1831                 goto zap_buffer_no_jh;
1832
1833         transaction = jh->b_transaction;
1834         if (transaction == NULL) {
1835                 /* First case: not on any transaction.  If it
1836                  * has no checkpoint link, then we can zap it:
1837                  * it's a writeback-mode buffer so we don't care
1838                  * if it hits disk safely. */
1839                 if (!jh->b_cp_transaction) {
1840                         JBUFFER_TRACE(jh, "not on any transaction: zap");
1841                         goto zap_buffer;
1842                 }
1843
1844                 if (!buffer_dirty(bh)) {
1845                         /* bdflush has written it.  We can drop it now */
1846                         goto zap_buffer;
1847                 }
1848
1849                 /* OK, it must be in the journal but still not
1850                  * written fully to disk: it's metadata or
1851                  * journaled data... */
1852
1853                 if (journal->j_running_transaction) {
1854                         /* ... and once the current transaction has
1855                          * committed, the buffer won't be needed any
1856                          * longer. */
1857                         JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1858                         ret = __dispose_buffer(jh,
1859                                         journal->j_running_transaction);
1860                         jbd2_journal_put_journal_head(jh);
1861                         spin_unlock(&journal->j_list_lock);
1862                         jbd_unlock_bh_state(bh);
1863                         spin_unlock(&journal->j_state_lock);
1864                         return ret;
1865                 } else {
1866                         /* There is no currently-running transaction. So the
1867                          * orphan record which we wrote for this file must have
1868                          * passed into commit.  We must attach this buffer to
1869                          * the committing transaction, if it exists. */
1870                         if (journal->j_committing_transaction) {
1871                                 JBUFFER_TRACE(jh, "give to committing trans");
1872                                 ret = __dispose_buffer(jh,
1873                                         journal->j_committing_transaction);
1874                                 jbd2_journal_put_journal_head(jh);
1875                                 spin_unlock(&journal->j_list_lock);
1876                                 jbd_unlock_bh_state(bh);
1877                                 spin_unlock(&journal->j_state_lock);
1878                                 return ret;
1879                         } else {
1880                                 /* The orphan record's transaction has
1881                                  * committed.  We can cleanse this buffer */
1882                                 clear_buffer_jbddirty(bh);
1883                                 goto zap_buffer;
1884                         }
1885                 }
1886         } else if (transaction == journal->j_committing_transaction) {
1887                 JBUFFER_TRACE(jh, "on committing transaction");
1888                 if (jh->b_jlist == BJ_Locked) {
1889                         /*
1890                          * The buffer is on the committing transaction's locked
1891                          * list.  We have the buffer locked, so I/O has
1892                          * completed.  So we can nail the buffer now.
1893                          */
1894                         may_free = __dispose_buffer(jh, transaction);
1895                         goto zap_buffer;
1896                 }
1897                 /*
1898                  * If it is committing, we simply cannot touch it.  We
1899                  * can remove it's next_transaction pointer from the
1900                  * running transaction if that is set, but nothing
1901                  * else. */
1902                 set_buffer_freed(bh);
1903                 if (jh->b_next_transaction) {
1904                         J_ASSERT(jh->b_next_transaction ==
1905                                         journal->j_running_transaction);
1906                         jh->b_next_transaction = NULL;
1907                 }
1908                 jbd2_journal_put_journal_head(jh);
1909                 spin_unlock(&journal->j_list_lock);
1910                 jbd_unlock_bh_state(bh);
1911                 spin_unlock(&journal->j_state_lock);
1912                 return 0;
1913         } else {
1914                 /* Good, the buffer belongs to the running transaction.
1915                  * We are writing our own transaction's data, not any
1916                  * previous one's, so it is safe to throw it away
1917                  * (remember that we expect the filesystem to have set
1918                  * i_size already for this truncate so recovery will not
1919                  * expose the disk blocks we are discarding here.) */
1920                 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
1921                 JBUFFER_TRACE(jh, "on running transaction");
1922                 may_free = __dispose_buffer(jh, transaction);
1923         }
1924
1925 zap_buffer:
1926         jbd2_journal_put_journal_head(jh);
1927 zap_buffer_no_jh:
1928         spin_unlock(&journal->j_list_lock);
1929         jbd_unlock_bh_state(bh);
1930         spin_unlock(&journal->j_state_lock);
1931 zap_buffer_unlocked:
1932         clear_buffer_dirty(bh);
1933         J_ASSERT_BH(bh, !buffer_jbddirty(bh));
1934         clear_buffer_mapped(bh);
1935         clear_buffer_req(bh);
1936         clear_buffer_new(bh);
1937         bh->b_bdev = NULL;
1938         return may_free;
1939 }
1940
1941 /**
1942  * void jbd2_journal_invalidatepage()
1943  * @journal: journal to use for flush...
1944  * @page:    page to flush
1945  * @offset:  length of page to invalidate.
1946  *
1947  * Reap page buffers containing data after offset in page.
1948  *
1949  */
1950 void jbd2_journal_invalidatepage(journal_t *journal,
1951                       struct page *page,
1952                       unsigned long offset)
1953 {
1954         struct buffer_head *head, *bh, *next;
1955         unsigned int curr_off = 0;
1956         int may_free = 1;
1957
1958         if (!PageLocked(page))
1959                 BUG();
1960         if (!page_has_buffers(page))
1961                 return;
1962
1963         /* We will potentially be playing with lists other than just the
1964          * data lists (especially for journaled data mode), so be
1965          * cautious in our locking. */
1966
1967         head = bh = page_buffers(page);
1968         do {
1969                 unsigned int next_off = curr_off + bh->b_size;
1970                 next = bh->b_this_page;
1971
1972                 if (offset <= curr_off) {
1973                         /* This block is wholly outside the truncation point */
1974                         lock_buffer(bh);
1975                         may_free &= journal_unmap_buffer(journal, bh);
1976                         unlock_buffer(bh);
1977                 }
1978                 curr_off = next_off;
1979                 bh = next;
1980
1981         } while (bh != head);
1982
1983         if (!offset) {
1984                 if (may_free && try_to_free_buffers(page))
1985                         J_ASSERT(!page_has_buffers(page));
1986         }
1987 }
1988
1989 /*
1990  * File a buffer on the given transaction list.
1991  */
1992 void __jbd2_journal_file_buffer(struct journal_head *jh,
1993                         transaction_t *transaction, int jlist)
1994 {
1995         struct journal_head **list = NULL;
1996         int was_dirty = 0;
1997         struct buffer_head *bh = jh2bh(jh);
1998
1999         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2000         assert_spin_locked(&transaction->t_journal->j_list_lock);
2001
2002         J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
2003         J_ASSERT_JH(jh, jh->b_transaction == transaction ||
2004                                 jh->b_transaction == NULL);
2005
2006         if (jh->b_transaction && jh->b_jlist == jlist)
2007                 return;
2008
2009         /* The following list of buffer states needs to be consistent
2010          * with __jbd_unexpected_dirty_buffer()'s handling of dirty
2011          * state. */
2012
2013         if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
2014             jlist == BJ_Shadow || jlist == BJ_Forget) {
2015                 if (test_clear_buffer_dirty(bh) ||
2016                     test_clear_buffer_jbddirty(bh))
2017                         was_dirty = 1;
2018         }
2019
2020         if (jh->b_transaction)
2021                 __jbd2_journal_temp_unlink_buffer(jh);
2022         jh->b_transaction = transaction;
2023
2024         switch (jlist) {
2025         case BJ_None:
2026                 J_ASSERT_JH(jh, !jh->b_committed_data);
2027                 J_ASSERT_JH(jh, !jh->b_frozen_data);
2028                 return;
2029         case BJ_SyncData:
2030                 list = &transaction->t_sync_datalist;
2031                 break;
2032         case BJ_Metadata:
2033                 transaction->t_nr_buffers++;
2034                 list = &transaction->t_buffers;
2035                 break;
2036         case BJ_Forget:
2037                 list = &transaction->t_forget;
2038                 break;
2039         case BJ_IO:
2040                 list = &transaction->t_iobuf_list;
2041                 break;
2042         case BJ_Shadow:
2043                 list = &transaction->t_shadow_list;
2044                 break;
2045         case BJ_LogCtl:
2046                 list = &transaction->t_log_list;
2047                 break;
2048         case BJ_Reserved:
2049                 list = &transaction->t_reserved_list;
2050                 break;
2051         case BJ_Locked:
2052                 list =  &transaction->t_locked_list;
2053                 break;
2054         }
2055
2056         __blist_add_buffer(list, jh);
2057         jh->b_jlist = jlist;
2058
2059         if (was_dirty)
2060                 set_buffer_jbddirty(bh);
2061 }
2062
2063 void jbd2_journal_file_buffer(struct journal_head *jh,
2064                                 transaction_t *transaction, int jlist)
2065 {
2066         jbd_lock_bh_state(jh2bh(jh));
2067         spin_lock(&transaction->t_journal->j_list_lock);
2068         __jbd2_journal_file_buffer(jh, transaction, jlist);
2069         spin_unlock(&transaction->t_journal->j_list_lock);
2070         jbd_unlock_bh_state(jh2bh(jh));
2071 }
2072
2073 /*
2074  * Remove a buffer from its current buffer list in preparation for
2075  * dropping it from its current transaction entirely.  If the buffer has
2076  * already started to be used by a subsequent transaction, refile the
2077  * buffer on that transaction's metadata list.
2078  *
2079  * Called under journal->j_list_lock
2080  *
2081  * Called under jbd_lock_bh_state(jh2bh(jh))
2082  */
2083 void __jbd2_journal_refile_buffer(struct journal_head *jh)
2084 {
2085         int was_dirty;
2086         struct buffer_head *bh = jh2bh(jh);
2087
2088         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2089         if (jh->b_transaction)
2090                 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2091
2092         /* If the buffer is now unused, just drop it. */
2093         if (jh->b_next_transaction == NULL) {
2094                 __jbd2_journal_unfile_buffer(jh);
2095                 return;
2096         }
2097
2098         /*
2099          * It has been modified by a later transaction: add it to the new
2100          * transaction's metadata list.
2101          */
2102
2103         was_dirty = test_clear_buffer_jbddirty(bh);
2104         __jbd2_journal_temp_unlink_buffer(jh);
2105         jh->b_transaction = jh->b_next_transaction;
2106         jh->b_next_transaction = NULL;
2107         __jbd2_journal_file_buffer(jh, jh->b_transaction,
2108                                 jh->b_modified ? BJ_Metadata : BJ_Reserved);
2109         J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2110
2111         if (was_dirty)
2112                 set_buffer_jbddirty(bh);
2113 }
2114
2115 /*
2116  * For the unlocked version of this call, also make sure that any
2117  * hanging journal_head is cleaned up if necessary.
2118  *
2119  * __jbd2_journal_refile_buffer is usually called as part of a single locked
2120  * operation on a buffer_head, in which the caller is probably going to
2121  * be hooking the journal_head onto other lists.  In that case it is up
2122  * to the caller to remove the journal_head if necessary.  For the
2123  * unlocked jbd2_journal_refile_buffer call, the caller isn't going to be
2124  * doing anything else to the buffer so we need to do the cleanup
2125  * ourselves to avoid a jh leak.
2126  *
2127  * *** The journal_head may be freed by this call! ***
2128  */
2129 void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2130 {
2131         struct buffer_head *bh = jh2bh(jh);
2132
2133         jbd_lock_bh_state(bh);
2134         spin_lock(&journal->j_list_lock);
2135
2136         __jbd2_journal_refile_buffer(jh);
2137         jbd_unlock_bh_state(bh);
2138         jbd2_journal_remove_journal_head(bh);
2139
2140         spin_unlock(&journal->j_list_lock);
2141         __brelse(bh);
2142 }