Pull platform-drivers into test branch
[linux-2.6] / fs / jbd2 / transaction.c
1 /*
2  * linux/fs/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/smp_lock.h>
27 #include <linux/mm.h>
28 #include <linux/highmem.h>
29
30 static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh);
31
32 /*
33  * jbd2_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
48 static transaction_t *
49 jbd2_get_transaction(journal_t *journal, transaction_t *transaction)
50 {
51         transaction->t_journal = journal;
52         transaction->t_state = T_RUNNING;
53         transaction->t_tid = journal->j_transaction_sequence++;
54         transaction->t_expires = jiffies + journal->j_commit_interval;
55         spin_lock_init(&transaction->t_handle_lock);
56
57         /* Set up the commit timer for the new transaction. */
58         journal->j_commit_timer.expires = transaction->t_expires;
59         add_timer(&journal->j_commit_timer);
60
61         J_ASSERT(journal->j_running_transaction == NULL);
62         journal->j_running_transaction = transaction;
63
64         return transaction;
65 }
66
67 /*
68  * Handle management.
69  *
70  * A handle_t is an object which represents a single atomic update to a
71  * filesystem, and which tracks all of the modifications which form part
72  * of that one update.
73  */
74
75 /*
76  * start_this_handle: Given a handle, deal with any locking or stalling
77  * needed to make sure that there is enough journal space for the handle
78  * to begin.  Attach the handle to a transaction and set up the
79  * transaction's buffer credits.
80  */
81
82 static int start_this_handle(journal_t *journal, handle_t *handle)
83 {
84         transaction_t *transaction;
85         int needed;
86         int nblocks = handle->h_buffer_credits;
87         transaction_t *new_transaction = NULL;
88         int ret = 0;
89
90         if (nblocks > journal->j_max_transaction_buffers) {
91                 printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
92                        current->comm, nblocks,
93                        journal->j_max_transaction_buffers);
94                 ret = -ENOSPC;
95                 goto out;
96         }
97
98 alloc_transaction:
99         if (!journal->j_running_transaction) {
100                 new_transaction = jbd_kmalloc(sizeof(*new_transaction),
101                                                 GFP_NOFS);
102                 if (!new_transaction) {
103                         ret = -ENOMEM;
104                         goto out;
105                 }
106                 memset(new_transaction, 0, sizeof(*new_transaction));
107         }
108
109         jbd_debug(3, "New handle %p going live.\n", handle);
110
111 repeat:
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);
118 repeat_locked:
119         if (is_journal_aborted(journal) ||
120             (journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) {
121                 spin_unlock(&journal->j_state_lock);
122                 ret = -EROFS;
123                 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                 jbd2_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                 __jbd2_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
187         /*
188          * 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
196          * in the new transaction.
197          *
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          * jbd2_journal_extend().
211          */
212         if (__jbd2_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                 __jbd2_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                   __jbd2_log_space_left(journal));
229         spin_unlock(&transaction->t_handle_lock);
230         spin_unlock(&journal->j_state_lock);
231 out:
232         if (unlikely(new_transaction))          /* It's usually NULL */
233                 kfree(new_transaction);
234         return ret;
235 }
236
237 /* Allocate a new handle.  This should probably be in a slab... */
238 static handle_t *new_handle(int nblocks)
239 {
240         handle_t *handle = jbd_alloc_handle(GFP_NOFS);
241         if (!handle)
242                 return NULL;
243         memset(handle, 0, sizeof(*handle));
244         handle->h_buffer_credits = nblocks;
245         handle->h_ref = 1;
246
247         return handle;
248 }
249
250 /**
251  * handle_t *jbd2_journal_start() - Obtain a new handle.
252  * @journal: Journal to start transaction on.
253  * @nblocks: number of block buffer we might modify
254  *
255  * We make sure that the transaction can guarantee at least nblocks of
256  * modified buffers in the log.  We block until the log can guarantee
257  * that much space.
258  *
259  * This function is visible to journal users (like ext3fs), so is not
260  * called with the journal already locked.
261  *
262  * Return a pointer to a newly allocated handle, or NULL on failure
263  */
264 handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
265 {
266         handle_t *handle = journal_current_handle();
267         int err;
268
269         if (!journal)
270                 return ERR_PTR(-EROFS);
271
272         if (handle) {
273                 J_ASSERT(handle->h_transaction->t_journal == journal);
274                 handle->h_ref++;
275                 return handle;
276         }
277
278         handle = new_handle(nblocks);
279         if (!handle)
280                 return ERR_PTR(-ENOMEM);
281
282         current->journal_info = handle;
283
284         err = start_this_handle(journal, handle);
285         if (err < 0) {
286                 jbd_free_handle(handle);
287                 current->journal_info = NULL;
288                 handle = ERR_PTR(err);
289         }
290         return handle;
291 }
292
293 /**
294  * int jbd2_journal_extend() - extend buffer credits.
295  * @handle:  handle to 'extend'
296  * @nblocks: nr blocks to try to extend by.
297  *
298  * Some transactions, such as large extends and truncates, can be done
299  * atomically all at once or in several stages.  The operation requests
300  * a credit for a number of buffer modications in advance, but can
301  * extend its credit if it needs more.
302  *
303  * jbd2_journal_extend tries to give the running handle more buffer credits.
304  * It does not guarantee that allocation - this is a best-effort only.
305  * The calling process MUST be able to deal cleanly with a failure to
306  * extend here.
307  *
308  * Return 0 on success, non-zero on failure.
309  *
310  * return code < 0 implies an error
311  * return code > 0 implies normal transaction-full status.
312  */
313 int jbd2_journal_extend(handle_t *handle, int nblocks)
314 {
315         transaction_t *transaction = handle->h_transaction;
316         journal_t *journal = transaction->t_journal;
317         int result;
318         int wanted;
319
320         result = -EIO;
321         if (is_handle_aborted(handle))
322                 goto out;
323
324         result = 1;
325
326         spin_lock(&journal->j_state_lock);
327
328         /* Don't extend a locked-down transaction! */
329         if (handle->h_transaction->t_state != T_RUNNING) {
330                 jbd_debug(3, "denied handle %p %d blocks: "
331                           "transaction not running\n", handle, nblocks);
332                 goto error_out;
333         }
334
335         spin_lock(&transaction->t_handle_lock);
336         wanted = transaction->t_outstanding_credits + nblocks;
337
338         if (wanted > journal->j_max_transaction_buffers) {
339                 jbd_debug(3, "denied handle %p %d blocks: "
340                           "transaction too large\n", handle, nblocks);
341                 goto unlock;
342         }
343
344         if (wanted > __jbd2_log_space_left(journal)) {
345                 jbd_debug(3, "denied handle %p %d blocks: "
346                           "insufficient log space\n", handle, nblocks);
347                 goto unlock;
348         }
349
350         handle->h_buffer_credits += nblocks;
351         transaction->t_outstanding_credits += nblocks;
352         result = 0;
353
354         jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
355 unlock:
356         spin_unlock(&transaction->t_handle_lock);
357 error_out:
358         spin_unlock(&journal->j_state_lock);
359 out:
360         return result;
361 }
362
363
364 /**
365  * int jbd2_journal_restart() - restart a handle .
366  * @handle:  handle to restart
367  * @nblocks: nr credits requested
368  *
369  * Restart a handle for a multi-transaction filesystem
370  * operation.
371  *
372  * If the jbd2_journal_extend() call above fails to grant new buffer credits
373  * to a running handle, a call to jbd2_journal_restart will commit the
374  * handle's transaction so far and reattach the handle to a new
375  * transaction capabable of guaranteeing the requested number of
376  * credits.
377  */
378
379 int jbd2_journal_restart(handle_t *handle, int nblocks)
380 {
381         transaction_t *transaction = handle->h_transaction;
382         journal_t *journal = transaction->t_journal;
383         int ret;
384
385         /* If we've had an abort of any type, don't even think about
386          * actually doing the restart! */
387         if (is_handle_aborted(handle))
388                 return 0;
389
390         /*
391          * First unlink the handle from its current transaction, and start the
392          * commit on that.
393          */
394         J_ASSERT(transaction->t_updates > 0);
395         J_ASSERT(journal_current_handle() == handle);
396
397         spin_lock(&journal->j_state_lock);
398         spin_lock(&transaction->t_handle_lock);
399         transaction->t_outstanding_credits -= handle->h_buffer_credits;
400         transaction->t_updates--;
401
402         if (!transaction->t_updates)
403                 wake_up(&journal->j_wait_updates);
404         spin_unlock(&transaction->t_handle_lock);
405
406         jbd_debug(2, "restarting handle %p\n", handle);
407         __jbd2_log_start_commit(journal, transaction->t_tid);
408         spin_unlock(&journal->j_state_lock);
409
410         handle->h_buffer_credits = nblocks;
411         ret = start_this_handle(journal, handle);
412         return ret;
413 }
414
415
416 /**
417  * void jbd2_journal_lock_updates () - establish a transaction barrier.
418  * @journal:  Journal to establish a barrier on.
419  *
420  * This locks out any further updates from being started, and blocks
421  * until all existing updates have completed, returning only once the
422  * journal is in a quiescent state with no updates running.
423  *
424  * The journal lock should not be held on entry.
425  */
426 void jbd2_journal_lock_updates(journal_t *journal)
427 {
428         DEFINE_WAIT(wait);
429
430         spin_lock(&journal->j_state_lock);
431         ++journal->j_barrier_count;
432
433         /* Wait until there are no running updates */
434         while (1) {
435                 transaction_t *transaction = journal->j_running_transaction;
436
437                 if (!transaction)
438                         break;
439
440                 spin_lock(&transaction->t_handle_lock);
441                 if (!transaction->t_updates) {
442                         spin_unlock(&transaction->t_handle_lock);
443                         break;
444                 }
445                 prepare_to_wait(&journal->j_wait_updates, &wait,
446                                 TASK_UNINTERRUPTIBLE);
447                 spin_unlock(&transaction->t_handle_lock);
448                 spin_unlock(&journal->j_state_lock);
449                 schedule();
450                 finish_wait(&journal->j_wait_updates, &wait);
451                 spin_lock(&journal->j_state_lock);
452         }
453         spin_unlock(&journal->j_state_lock);
454
455         /*
456          * We have now established a barrier against other normal updates, but
457          * we also need to barrier against other jbd2_journal_lock_updates() calls
458          * to make sure that we serialise special journal-locked operations
459          * too.
460          */
461         mutex_lock(&journal->j_barrier);
462 }
463
464 /**
465  * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier
466  * @journal:  Journal to release the barrier on.
467  *
468  * Release a transaction barrier obtained with jbd2_journal_lock_updates().
469  *
470  * Should be called without the journal lock held.
471  */
472 void jbd2_journal_unlock_updates (journal_t *journal)
473 {
474         J_ASSERT(journal->j_barrier_count != 0);
475
476         mutex_unlock(&journal->j_barrier);
477         spin_lock(&journal->j_state_lock);
478         --journal->j_barrier_count;
479         spin_unlock(&journal->j_state_lock);
480         wake_up(&journal->j_wait_transaction_locked);
481 }
482
483 /*
484  * Report any unexpected dirty buffers which turn up.  Normally those
485  * indicate an error, but they can occur if the user is running (say)
486  * tune2fs to modify the live filesystem, so we need the option of
487  * continuing as gracefully as possible.  #
488  *
489  * The caller should already hold the journal lock and
490  * j_list_lock spinlock: most callers will need those anyway
491  * in order to probe the buffer's journaling state safely.
492  */
493 static void jbd_unexpected_dirty_buffer(struct journal_head *jh)
494 {
495         int jlist;
496
497         /* If this buffer is one which might reasonably be dirty
498          * --- ie. data, or not part of this journal --- then
499          * we're OK to leave it alone, but otherwise we need to
500          * move the dirty bit to the journal's own internal
501          * JBDDirty bit. */
502         jlist = jh->b_jlist;
503
504         if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
505             jlist == BJ_Shadow || jlist == BJ_Forget) {
506                 struct buffer_head *bh = jh2bh(jh);
507
508                 if (test_clear_buffer_dirty(bh))
509                         set_buffer_jbddirty(bh);
510         }
511 }
512
513 /*
514  * If the buffer is already part of the current transaction, then there
515  * is nothing we need to do.  If it is already part of a prior
516  * transaction which we are still committing to disk, then we need to
517  * make sure that we do not overwrite the old copy: we do copy-out to
518  * preserve the copy going to disk.  We also account the buffer against
519  * the handle's metadata buffer credits (unless the buffer is already
520  * part of the transaction, that is).
521  *
522  */
523 static int
524 do_get_write_access(handle_t *handle, struct journal_head *jh,
525                         int force_copy)
526 {
527         struct buffer_head *bh;
528         transaction_t *transaction;
529         journal_t *journal;
530         int error;
531         char *frozen_buffer = NULL;
532         int need_copy = 0;
533
534         if (is_handle_aborted(handle))
535                 return -EROFS;
536
537         transaction = handle->h_transaction;
538         journal = transaction->t_journal;
539
540         jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy);
541
542         JBUFFER_TRACE(jh, "entry");
543 repeat:
544         bh = jh2bh(jh);
545
546         /* @@@ Need to check for errors here at some point. */
547
548         lock_buffer(bh);
549         jbd_lock_bh_state(bh);
550
551         /* We now hold the buffer lock so it is safe to query the buffer
552          * state.  Is the buffer dirty?
553          *
554          * If so, there are two possibilities.  The buffer may be
555          * non-journaled, and undergoing a quite legitimate writeback.
556          * Otherwise, it is journaled, and we don't expect dirty buffers
557          * in that state (the buffers should be marked JBD_Dirty
558          * instead.)  So either the IO is being done under our own
559          * control and this is a bug, or it's a third party IO such as
560          * dump(8) (which may leave the buffer scheduled for read ---
561          * ie. locked but not dirty) or tune2fs (which may actually have
562          * the buffer dirtied, ugh.)  */
563
564         if (buffer_dirty(bh)) {
565                 /*
566                  * First question: is this buffer already part of the current
567                  * transaction or the existing committing transaction?
568                  */
569                 if (jh->b_transaction) {
570                         J_ASSERT_JH(jh,
571                                 jh->b_transaction == transaction ||
572                                 jh->b_transaction ==
573                                         journal->j_committing_transaction);
574                         if (jh->b_next_transaction)
575                                 J_ASSERT_JH(jh, jh->b_next_transaction ==
576                                                         transaction);
577                 }
578                 /*
579                  * In any case we need to clean the dirty flag and we must
580                  * do it under the buffer lock to be sure we don't race
581                  * with running write-out.
582                  */
583                 JBUFFER_TRACE(jh, "Unexpected dirty buffer");
584                 jbd_unexpected_dirty_buffer(jh);
585         }
586
587         unlock_buffer(bh);
588
589         error = -EROFS;
590         if (is_handle_aborted(handle)) {
591                 jbd_unlock_bh_state(bh);
592                 goto out;
593         }
594         error = 0;
595
596         /*
597          * The buffer is already part of this transaction if b_transaction or
598          * b_next_transaction points to it
599          */
600         if (jh->b_transaction == transaction ||
601             jh->b_next_transaction == transaction)
602                 goto done;
603
604         /*
605          * If there is already a copy-out version of this buffer, then we don't
606          * need to make another one
607          */
608         if (jh->b_frozen_data) {
609                 JBUFFER_TRACE(jh, "has frozen data");
610                 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
611                 jh->b_next_transaction = transaction;
612                 goto done;
613         }
614
615         /* Is there data here we need to preserve? */
616
617         if (jh->b_transaction && jh->b_transaction != transaction) {
618                 JBUFFER_TRACE(jh, "owned by older transaction");
619                 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
620                 J_ASSERT_JH(jh, jh->b_transaction ==
621                                         journal->j_committing_transaction);
622
623                 /* There is one case we have to be very careful about.
624                  * If the committing transaction is currently writing
625                  * this buffer out to disk and has NOT made a copy-out,
626                  * then we cannot modify the buffer contents at all
627                  * right now.  The essence of copy-out is that it is the
628                  * extra copy, not the primary copy, which gets
629                  * journaled.  If the primary copy is already going to
630                  * disk then we cannot do copy-out here. */
631
632                 if (jh->b_jlist == BJ_Shadow) {
633                         DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
634                         wait_queue_head_t *wqh;
635
636                         wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
637
638                         JBUFFER_TRACE(jh, "on shadow: sleep");
639                         jbd_unlock_bh_state(bh);
640                         /* commit wakes up all shadow buffers after IO */
641                         for ( ; ; ) {
642                                 prepare_to_wait(wqh, &wait.wait,
643                                                 TASK_UNINTERRUPTIBLE);
644                                 if (jh->b_jlist != BJ_Shadow)
645                                         break;
646                                 schedule();
647                         }
648                         finish_wait(wqh, &wait.wait);
649                         goto repeat;
650                 }
651
652                 /* Only do the copy if the currently-owning transaction
653                  * still needs it.  If it is on the Forget list, the
654                  * committing transaction is past that stage.  The
655                  * buffer had better remain locked during the kmalloc,
656                  * but that should be true --- we hold the journal lock
657                  * still and the buffer is already on the BUF_JOURNAL
658                  * list so won't be flushed.
659                  *
660                  * Subtle point, though: if this is a get_undo_access,
661                  * then we will be relying on the frozen_data to contain
662                  * the new value of the committed_data record after the
663                  * transaction, so we HAVE to force the frozen_data copy
664                  * in that case. */
665
666                 if (jh->b_jlist != BJ_Forget || force_copy) {
667                         JBUFFER_TRACE(jh, "generate frozen data");
668                         if (!frozen_buffer) {
669                                 JBUFFER_TRACE(jh, "allocate memory for buffer");
670                                 jbd_unlock_bh_state(bh);
671                                 frozen_buffer =
672                                         jbd2_slab_alloc(jh2bh(jh)->b_size,
673                                                          GFP_NOFS);
674                                 if (!frozen_buffer) {
675                                         printk(KERN_EMERG
676                                                "%s: OOM for frozen_buffer\n",
677                                                __FUNCTION__);
678                                         JBUFFER_TRACE(jh, "oom!");
679                                         error = -ENOMEM;
680                                         jbd_lock_bh_state(bh);
681                                         goto done;
682                                 }
683                                 goto repeat;
684                         }
685                         jh->b_frozen_data = frozen_buffer;
686                         frozen_buffer = NULL;
687                         need_copy = 1;
688                 }
689                 jh->b_next_transaction = transaction;
690         }
691
692
693         /*
694          * Finally, if the buffer is not journaled right now, we need to make
695          * sure it doesn't get written to disk before the caller actually
696          * commits the new data
697          */
698         if (!jh->b_transaction) {
699                 JBUFFER_TRACE(jh, "no transaction");
700                 J_ASSERT_JH(jh, !jh->b_next_transaction);
701                 jh->b_transaction = transaction;
702                 JBUFFER_TRACE(jh, "file as BJ_Reserved");
703                 spin_lock(&journal->j_list_lock);
704                 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
705                 spin_unlock(&journal->j_list_lock);
706         }
707
708 done:
709         if (need_copy) {
710                 struct page *page;
711                 int offset;
712                 char *source;
713
714                 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
715                             "Possible IO failure.\n");
716                 page = jh2bh(jh)->b_page;
717                 offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK;
718                 source = kmap_atomic(page, KM_USER0);
719                 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
720                 kunmap_atomic(source, KM_USER0);
721         }
722         jbd_unlock_bh_state(bh);
723
724         /*
725          * If we are about to journal a buffer, then any revoke pending on it is
726          * no longer valid
727          */
728         jbd2_journal_cancel_revoke(handle, jh);
729
730 out:
731         if (unlikely(frozen_buffer))    /* It's usually NULL */
732                 jbd2_slab_free(frozen_buffer, bh->b_size);
733
734         JBUFFER_TRACE(jh, "exit");
735         return error;
736 }
737
738 /**
739  * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
740  * @handle: transaction to add buffer modifications to
741  * @bh:     bh to be used for metadata writes
742  * @credits: variable that will receive credits for the buffer
743  *
744  * Returns an error code or 0 on success.
745  *
746  * In full data journalling mode the buffer may be of type BJ_AsyncData,
747  * because we're write()ing a buffer which is also part of a shared mapping.
748  */
749
750 int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
751 {
752         struct journal_head *jh = jbd2_journal_add_journal_head(bh);
753         int rc;
754
755         /* We do not want to get caught playing with fields which the
756          * log thread also manipulates.  Make sure that the buffer
757          * completes any outstanding IO before proceeding. */
758         rc = do_get_write_access(handle, jh, 0);
759         jbd2_journal_put_journal_head(jh);
760         return rc;
761 }
762
763
764 /*
765  * When the user wants to journal a newly created buffer_head
766  * (ie. getblk() returned a new buffer and we are going to populate it
767  * manually rather than reading off disk), then we need to keep the
768  * buffer_head locked until it has been completely filled with new
769  * data.  In this case, we should be able to make the assertion that
770  * the bh is not already part of an existing transaction.
771  *
772  * The buffer should already be locked by the caller by this point.
773  * There is no lock ranking violation: it was a newly created,
774  * unlocked buffer beforehand. */
775
776 /**
777  * int jbd2_journal_get_create_access () - notify intent to use newly created bh
778  * @handle: transaction to new buffer to
779  * @bh: new buffer.
780  *
781  * Call this if you create a new bh.
782  */
783 int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
784 {
785         transaction_t *transaction = handle->h_transaction;
786         journal_t *journal = transaction->t_journal;
787         struct journal_head *jh = jbd2_journal_add_journal_head(bh);
788         int err;
789
790         jbd_debug(5, "journal_head %p\n", jh);
791         err = -EROFS;
792         if (is_handle_aborted(handle))
793                 goto out;
794         err = 0;
795
796         JBUFFER_TRACE(jh, "entry");
797         /*
798          * The buffer may already belong to this transaction due to pre-zeroing
799          * in the filesystem's new_block code.  It may also be on the previous,
800          * committing transaction's lists, but it HAS to be in Forget state in
801          * that case: the transaction must have deleted the buffer for it to be
802          * reused here.
803          */
804         jbd_lock_bh_state(bh);
805         spin_lock(&journal->j_list_lock);
806         J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
807                 jh->b_transaction == NULL ||
808                 (jh->b_transaction == journal->j_committing_transaction &&
809                           jh->b_jlist == BJ_Forget)));
810
811         J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
812         J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
813
814         if (jh->b_transaction == NULL) {
815                 jh->b_transaction = transaction;
816                 JBUFFER_TRACE(jh, "file as BJ_Reserved");
817                 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
818         } else if (jh->b_transaction == journal->j_committing_transaction) {
819                 JBUFFER_TRACE(jh, "set next transaction");
820                 jh->b_next_transaction = transaction;
821         }
822         spin_unlock(&journal->j_list_lock);
823         jbd_unlock_bh_state(bh);
824
825         /*
826          * akpm: I added this.  ext3_alloc_branch can pick up new indirect
827          * blocks which contain freed but then revoked metadata.  We need
828          * to cancel the revoke in case we end up freeing it yet again
829          * and the reallocating as data - this would cause a second revoke,
830          * which hits an assertion error.
831          */
832         JBUFFER_TRACE(jh, "cancelling revoke");
833         jbd2_journal_cancel_revoke(handle, jh);
834         jbd2_journal_put_journal_head(jh);
835 out:
836         return err;
837 }
838
839 /**
840  * int jbd2_journal_get_undo_access() -  Notify intent to modify metadata with
841  *     non-rewindable consequences
842  * @handle: transaction
843  * @bh: buffer to undo
844  * @credits: store the number of taken credits here (if not NULL)
845  *
846  * Sometimes there is a need to distinguish between metadata which has
847  * been committed to disk and that which has not.  The ext3fs code uses
848  * this for freeing and allocating space, we have to make sure that we
849  * do not reuse freed space until the deallocation has been committed,
850  * since if we overwrote that space we would make the delete
851  * un-rewindable in case of a crash.
852  *
853  * To deal with that, jbd2_journal_get_undo_access requests write access to a
854  * buffer for parts of non-rewindable operations such as delete
855  * operations on the bitmaps.  The journaling code must keep a copy of
856  * the buffer's contents prior to the undo_access call until such time
857  * as we know that the buffer has definitely been committed to disk.
858  *
859  * We never need to know which transaction the committed data is part
860  * of, buffers touched here are guaranteed to be dirtied later and so
861  * will be committed to a new transaction in due course, at which point
862  * we can discard the old committed data pointer.
863  *
864  * Returns error number or 0 on success.
865  */
866 int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
867 {
868         int err;
869         struct journal_head *jh = jbd2_journal_add_journal_head(bh);
870         char *committed_data = NULL;
871
872         JBUFFER_TRACE(jh, "entry");
873
874         /*
875          * Do this first --- it can drop the journal lock, so we want to
876          * make sure that obtaining the committed_data is done
877          * atomically wrt. completion of any outstanding commits.
878          */
879         err = do_get_write_access(handle, jh, 1);
880         if (err)
881                 goto out;
882
883 repeat:
884         if (!jh->b_committed_data) {
885                 committed_data = jbd2_slab_alloc(jh2bh(jh)->b_size, GFP_NOFS);
886                 if (!committed_data) {
887                         printk(KERN_EMERG "%s: No memory for committed data\n",
888                                 __FUNCTION__);
889                         err = -ENOMEM;
890                         goto out;
891                 }
892         }
893
894         jbd_lock_bh_state(bh);
895         if (!jh->b_committed_data) {
896                 /* Copy out the current buffer contents into the
897                  * preserved, committed copy. */
898                 JBUFFER_TRACE(jh, "generate b_committed data");
899                 if (!committed_data) {
900                         jbd_unlock_bh_state(bh);
901                         goto repeat;
902                 }
903
904                 jh->b_committed_data = committed_data;
905                 committed_data = NULL;
906                 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
907         }
908         jbd_unlock_bh_state(bh);
909 out:
910         jbd2_journal_put_journal_head(jh);
911         if (unlikely(committed_data))
912                 jbd2_slab_free(committed_data, bh->b_size);
913         return err;
914 }
915
916 /**
917  * int jbd2_journal_dirty_data() -  mark a buffer as containing dirty data which
918  *                             needs to be flushed before we can commit the
919  *                             current transaction.
920  * @handle: transaction
921  * @bh: bufferhead to mark
922  *
923  * The buffer is placed on the transaction's data list and is marked as
924  * belonging to the transaction.
925  *
926  * Returns error number or 0 on success.
927  *
928  * jbd2_journal_dirty_data() can be called via page_launder->ext3_writepage
929  * by kswapd.
930  */
931 int jbd2_journal_dirty_data(handle_t *handle, struct buffer_head *bh)
932 {
933         journal_t *journal = handle->h_transaction->t_journal;
934         int need_brelse = 0;
935         struct journal_head *jh;
936
937         if (is_handle_aborted(handle))
938                 return 0;
939
940         jh = jbd2_journal_add_journal_head(bh);
941         JBUFFER_TRACE(jh, "entry");
942
943         /*
944          * The buffer could *already* be dirty.  Writeout can start
945          * at any time.
946          */
947         jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
948
949         /*
950          * What if the buffer is already part of a running transaction?
951          *
952          * There are two cases:
953          * 1) It is part of the current running transaction.  Refile it,
954          *    just in case we have allocated it as metadata, deallocated
955          *    it, then reallocated it as data.
956          * 2) It is part of the previous, still-committing transaction.
957          *    If all we want to do is to guarantee that the buffer will be
958          *    written to disk before this new transaction commits, then
959          *    being sure that the *previous* transaction has this same
960          *    property is sufficient for us!  Just leave it on its old
961          *    transaction.
962          *
963          * In case (2), the buffer must not already exist as metadata
964          * --- that would violate write ordering (a transaction is free
965          * to write its data at any point, even before the previous
966          * committing transaction has committed).  The caller must
967          * never, ever allow this to happen: there's nothing we can do
968          * about it in this layer.
969          */
970         jbd_lock_bh_state(bh);
971         spin_lock(&journal->j_list_lock);
972
973         /* Now that we have bh_state locked, are we really still mapped? */
974         if (!buffer_mapped(bh)) {
975                 JBUFFER_TRACE(jh, "unmapped buffer, bailing out");
976                 goto no_journal;
977         }
978
979         if (jh->b_transaction) {
980                 JBUFFER_TRACE(jh, "has transaction");
981                 if (jh->b_transaction != handle->h_transaction) {
982                         JBUFFER_TRACE(jh, "belongs to older transaction");
983                         J_ASSERT_JH(jh, jh->b_transaction ==
984                                         journal->j_committing_transaction);
985
986                         /* @@@ IS THIS TRUE  ? */
987                         /*
988                          * Not any more.  Scenario: someone does a write()
989                          * in data=journal mode.  The buffer's transaction has
990                          * moved into commit.  Then someone does another
991                          * write() to the file.  We do the frozen data copyout
992                          * and set b_next_transaction to point to j_running_t.
993                          * And while we're in that state, someone does a
994                          * writepage() in an attempt to pageout the same area
995                          * of the file via a shared mapping.  At present that
996                          * calls jbd2_journal_dirty_data(), and we get right here.
997                          * It may be too late to journal the data.  Simply
998                          * falling through to the next test will suffice: the
999                          * data will be dirty and wil be checkpointed.  The
1000                          * ordering comments in the next comment block still
1001                          * apply.
1002                          */
1003                         //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1004
1005                         /*
1006                          * If we're journalling data, and this buffer was
1007                          * subject to a write(), it could be metadata, forget
1008                          * or shadow against the committing transaction.  Now,
1009                          * someone has dirtied the same darn page via a mapping
1010                          * and it is being writepage()'d.
1011                          * We *could* just steal the page from commit, with some
1012                          * fancy locking there.  Instead, we just skip it -
1013                          * don't tie the page's buffers to the new transaction
1014                          * at all.
1015                          * Implication: if we crash before the writepage() data
1016                          * is written into the filesystem, recovery will replay
1017                          * the write() data.
1018                          */
1019                         if (jh->b_jlist != BJ_None &&
1020                                         jh->b_jlist != BJ_SyncData &&
1021                                         jh->b_jlist != BJ_Locked) {
1022                                 JBUFFER_TRACE(jh, "Not stealing");
1023                                 goto no_journal;
1024                         }
1025
1026                         /*
1027                          * This buffer may be undergoing writeout in commit.  We
1028                          * can't return from here and let the caller dirty it
1029                          * again because that can cause the write-out loop in
1030                          * commit to never terminate.
1031                          */
1032                         if (buffer_dirty(bh)) {
1033                                 get_bh(bh);
1034                                 spin_unlock(&journal->j_list_lock);
1035                                 jbd_unlock_bh_state(bh);
1036                                 need_brelse = 1;
1037                                 sync_dirty_buffer(bh);
1038                                 jbd_lock_bh_state(bh);
1039                                 spin_lock(&journal->j_list_lock);
1040                                 /* Since we dropped the lock... */
1041                                 if (!buffer_mapped(bh)) {
1042                                         JBUFFER_TRACE(jh, "buffer got unmapped");
1043                                         goto no_journal;
1044                                 }
1045                                 /* The buffer may become locked again at any
1046                                    time if it is redirtied */
1047                         }
1048
1049                         /* journal_clean_data_list() may have got there first */
1050                         if (jh->b_transaction != NULL) {
1051                                 JBUFFER_TRACE(jh, "unfile from commit");
1052                                 __jbd2_journal_temp_unlink_buffer(jh);
1053                                 /* It still points to the committing
1054                                  * transaction; move it to this one so
1055                                  * that the refile assert checks are
1056                                  * happy. */
1057                                 jh->b_transaction = handle->h_transaction;
1058                         }
1059                         /* The buffer will be refiled below */
1060
1061                 }
1062                 /*
1063                  * Special case --- the buffer might actually have been
1064                  * allocated and then immediately deallocated in the previous,
1065                  * committing transaction, so might still be left on that
1066                  * transaction's metadata lists.
1067                  */
1068                 if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
1069                         JBUFFER_TRACE(jh, "not on correct data list: unfile");
1070                         J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
1071                         __jbd2_journal_temp_unlink_buffer(jh);
1072                         jh->b_transaction = handle->h_transaction;
1073                         JBUFFER_TRACE(jh, "file as data");
1074                         __jbd2_journal_file_buffer(jh, handle->h_transaction,
1075                                                 BJ_SyncData);
1076                 }
1077         } else {
1078                 JBUFFER_TRACE(jh, "not on a transaction");
1079                 __jbd2_journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
1080         }
1081 no_journal:
1082         spin_unlock(&journal->j_list_lock);
1083         jbd_unlock_bh_state(bh);
1084         if (need_brelse) {
1085                 BUFFER_TRACE(bh, "brelse");
1086                 __brelse(bh);
1087         }
1088         JBUFFER_TRACE(jh, "exit");
1089         jbd2_journal_put_journal_head(jh);
1090         return 0;
1091 }
1092
1093 /**
1094  * int jbd2_journal_dirty_metadata() -  mark a buffer as containing dirty metadata
1095  * @handle: transaction to add buffer to.
1096  * @bh: buffer to mark
1097  *
1098  * mark dirty metadata which needs to be journaled as part of the current
1099  * transaction.
1100  *
1101  * The buffer is placed on the transaction's metadata list and is marked
1102  * as belonging to the transaction.
1103  *
1104  * Returns error number or 0 on success.
1105  *
1106  * Special care needs to be taken if the buffer already belongs to the
1107  * current committing transaction (in which case we should have frozen
1108  * data present for that commit).  In that case, we don't relink the
1109  * buffer: that only gets done when the old transaction finally
1110  * completes its commit.
1111  */
1112 int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1113 {
1114         transaction_t *transaction = handle->h_transaction;
1115         journal_t *journal = transaction->t_journal;
1116         struct journal_head *jh = bh2jh(bh);
1117
1118         jbd_debug(5, "journal_head %p\n", jh);
1119         JBUFFER_TRACE(jh, "entry");
1120         if (is_handle_aborted(handle))
1121                 goto out;
1122
1123         jbd_lock_bh_state(bh);
1124
1125         if (jh->b_modified == 0) {
1126                 /*
1127                  * This buffer's got modified and becoming part
1128                  * of the transaction. This needs to be done
1129                  * once a transaction -bzzz
1130                  */
1131                 jh->b_modified = 1;
1132                 J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
1133                 handle->h_buffer_credits--;
1134         }
1135
1136         /*
1137          * fastpath, to avoid expensive locking.  If this buffer is already
1138          * on the running transaction's metadata list there is nothing to do.
1139          * Nobody can take it off again because there is a handle open.
1140          * I _think_ we're OK here with SMP barriers - a mistaken decision will
1141          * result in this test being false, so we go in and take the locks.
1142          */
1143         if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1144                 JBUFFER_TRACE(jh, "fastpath");
1145                 J_ASSERT_JH(jh, jh->b_transaction ==
1146                                         journal->j_running_transaction);
1147                 goto out_unlock_bh;
1148         }
1149
1150         set_buffer_jbddirty(bh);
1151
1152         /*
1153          * Metadata already on the current transaction list doesn't
1154          * need to be filed.  Metadata on another transaction's list must
1155          * be committing, and will be refiled once the commit completes:
1156          * leave it alone for now.
1157          */
1158         if (jh->b_transaction != transaction) {
1159                 JBUFFER_TRACE(jh, "already on other transaction");
1160                 J_ASSERT_JH(jh, jh->b_transaction ==
1161                                         journal->j_committing_transaction);
1162                 J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
1163                 /* And this case is illegal: we can't reuse another
1164                  * transaction's data buffer, ever. */
1165                 goto out_unlock_bh;
1166         }
1167
1168         /* That test should have eliminated the following case: */
1169         J_ASSERT_JH(jh, jh->b_frozen_data == 0);
1170
1171         JBUFFER_TRACE(jh, "file as BJ_Metadata");
1172         spin_lock(&journal->j_list_lock);
1173         __jbd2_journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1174         spin_unlock(&journal->j_list_lock);
1175 out_unlock_bh:
1176         jbd_unlock_bh_state(bh);
1177 out:
1178         JBUFFER_TRACE(jh, "exit");
1179         return 0;
1180 }
1181
1182 /*
1183  * jbd2_journal_release_buffer: undo a get_write_access without any buffer
1184  * updates, if the update decided in the end that it didn't need access.
1185  *
1186  */
1187 void
1188 jbd2_journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1189 {
1190         BUFFER_TRACE(bh, "entry");
1191 }
1192
1193 /**
1194  * void jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1195  * @handle: transaction handle
1196  * @bh:     bh to 'forget'
1197  *
1198  * We can only do the bforget if there are no commits pending against the
1199  * buffer.  If the buffer is dirty in the current running transaction we
1200  * can safely unlink it.
1201  *
1202  * bh may not be a journalled buffer at all - it may be a non-JBD
1203  * buffer which came off the hashtable.  Check for this.
1204  *
1205  * Decrements bh->b_count by one.
1206  *
1207  * Allow this call even if the handle has aborted --- it may be part of
1208  * the caller's cleanup after an abort.
1209  */
1210 int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh)
1211 {
1212         transaction_t *transaction = handle->h_transaction;
1213         journal_t *journal = transaction->t_journal;
1214         struct journal_head *jh;
1215         int drop_reserve = 0;
1216         int err = 0;
1217
1218         BUFFER_TRACE(bh, "entry");
1219
1220         jbd_lock_bh_state(bh);
1221         spin_lock(&journal->j_list_lock);
1222
1223         if (!buffer_jbd(bh))
1224                 goto not_jbd;
1225         jh = bh2jh(bh);
1226
1227         /* Critical error: attempting to delete a bitmap buffer, maybe?
1228          * Don't do any jbd operations, and return an error. */
1229         if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1230                          "inconsistent data on disk")) {
1231                 err = -EIO;
1232                 goto not_jbd;
1233         }
1234
1235         /*
1236          * The buffer's going from the transaction, we must drop
1237          * all references -bzzz
1238          */
1239         jh->b_modified = 0;
1240
1241         if (jh->b_transaction == handle->h_transaction) {
1242                 J_ASSERT_JH(jh, !jh->b_frozen_data);
1243
1244                 /* If we are forgetting a buffer which is already part
1245                  * of this transaction, then we can just drop it from
1246                  * the transaction immediately. */
1247                 clear_buffer_dirty(bh);
1248                 clear_buffer_jbddirty(bh);
1249
1250                 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1251
1252                 drop_reserve = 1;
1253
1254                 /*
1255                  * We are no longer going to journal this buffer.
1256                  * However, the commit of this transaction is still
1257                  * important to the buffer: the delete that we are now
1258                  * processing might obsolete an old log entry, so by
1259                  * committing, we can satisfy the buffer's checkpoint.
1260                  *
1261                  * So, if we have a checkpoint on the buffer, we should
1262                  * now refile the buffer on our BJ_Forget list so that
1263                  * we know to remove the checkpoint after we commit.
1264                  */
1265
1266                 if (jh->b_cp_transaction) {
1267                         __jbd2_journal_temp_unlink_buffer(jh);
1268                         __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1269                 } else {
1270                         __jbd2_journal_unfile_buffer(jh);
1271                         jbd2_journal_remove_journal_head(bh);
1272                         __brelse(bh);
1273                         if (!buffer_jbd(bh)) {
1274                                 spin_unlock(&journal->j_list_lock);
1275                                 jbd_unlock_bh_state(bh);
1276                                 __bforget(bh);
1277                                 goto drop;
1278                         }
1279                 }
1280         } else if (jh->b_transaction) {
1281                 J_ASSERT_JH(jh, (jh->b_transaction ==
1282                                  journal->j_committing_transaction));
1283                 /* However, if the buffer is still owned by a prior
1284                  * (committing) transaction, we can't drop it yet... */
1285                 JBUFFER_TRACE(jh, "belongs to older transaction");
1286                 /* ... but we CAN drop it from the new transaction if we
1287                  * have also modified it since the original commit. */
1288
1289                 if (jh->b_next_transaction) {
1290                         J_ASSERT(jh->b_next_transaction == transaction);
1291                         jh->b_next_transaction = NULL;
1292                         drop_reserve = 1;
1293                 }
1294         }
1295
1296 not_jbd:
1297         spin_unlock(&journal->j_list_lock);
1298         jbd_unlock_bh_state(bh);
1299         __brelse(bh);
1300 drop:
1301         if (drop_reserve) {
1302                 /* no need to reserve log space for this block -bzzz */
1303                 handle->h_buffer_credits++;
1304         }
1305         return err;
1306 }
1307
1308 /**
1309  * int jbd2_journal_stop() - complete a transaction
1310  * @handle: tranaction to complete.
1311  *
1312  * All done for a particular handle.
1313  *
1314  * There is not much action needed here.  We just return any remaining
1315  * buffer credits to the transaction and remove the handle.  The only
1316  * complication is that we need to start a commit operation if the
1317  * filesystem is marked for synchronous update.
1318  *
1319  * jbd2_journal_stop itself will not usually return an error, but it may
1320  * do so in unusual circumstances.  In particular, expect it to
1321  * return -EIO if a jbd2_journal_abort has been executed since the
1322  * transaction began.
1323  */
1324 int jbd2_journal_stop(handle_t *handle)
1325 {
1326         transaction_t *transaction = handle->h_transaction;
1327         journal_t *journal = transaction->t_journal;
1328         int old_handle_count, err;
1329         pid_t pid;
1330
1331         J_ASSERT(journal_current_handle() == handle);
1332
1333         if (is_handle_aborted(handle))
1334                 err = -EIO;
1335         else {
1336                 J_ASSERT(transaction->t_updates > 0);
1337                 err = 0;
1338         }
1339
1340         if (--handle->h_ref > 0) {
1341                 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1342                           handle->h_ref);
1343                 return err;
1344         }
1345
1346         jbd_debug(4, "Handle %p going down\n", handle);
1347
1348         /*
1349          * Implement synchronous transaction batching.  If the handle
1350          * was synchronous, don't force a commit immediately.  Let's
1351          * yield and let another thread piggyback onto this transaction.
1352          * Keep doing that while new threads continue to arrive.
1353          * It doesn't cost much - we're about to run a commit and sleep
1354          * on IO anyway.  Speeds up many-threaded, many-dir operations
1355          * by 30x or more...
1356          *
1357          * But don't do this if this process was the most recent one to
1358          * perform a synchronous write.  We do this to detect the case where a
1359          * single process is doing a stream of sync writes.  No point in waiting
1360          * for joiners in that case.
1361          */
1362         pid = current->pid;
1363         if (handle->h_sync && journal->j_last_sync_writer != pid) {
1364                 journal->j_last_sync_writer = pid;
1365                 do {
1366                         old_handle_count = transaction->t_handle_count;
1367                         schedule_timeout_uninterruptible(1);
1368                 } while (old_handle_count != transaction->t_handle_count);
1369         }
1370
1371         current->journal_info = NULL;
1372         spin_lock(&journal->j_state_lock);
1373         spin_lock(&transaction->t_handle_lock);
1374         transaction->t_outstanding_credits -= handle->h_buffer_credits;
1375         transaction->t_updates--;
1376         if (!transaction->t_updates) {
1377                 wake_up(&journal->j_wait_updates);
1378                 if (journal->j_barrier_count)
1379                         wake_up(&journal->j_wait_transaction_locked);
1380         }
1381
1382         /*
1383          * If the handle is marked SYNC, we need to set another commit
1384          * going!  We also want to force a commit if the current
1385          * transaction is occupying too much of the log, or if the
1386          * transaction is too old now.
1387          */
1388         if (handle->h_sync ||
1389                         transaction->t_outstanding_credits >
1390                                 journal->j_max_transaction_buffers ||
1391                         time_after_eq(jiffies, transaction->t_expires)) {
1392                 /* Do this even for aborted journals: an abort still
1393                  * completes the commit thread, it just doesn't write
1394                  * anything to disk. */
1395                 tid_t tid = transaction->t_tid;
1396
1397                 spin_unlock(&transaction->t_handle_lock);
1398                 jbd_debug(2, "transaction too old, requesting commit for "
1399                                         "handle %p\n", handle);
1400                 /* This is non-blocking */
1401                 __jbd2_log_start_commit(journal, transaction->t_tid);
1402                 spin_unlock(&journal->j_state_lock);
1403
1404                 /*
1405                  * Special case: JBD2_SYNC synchronous updates require us
1406                  * to wait for the commit to complete.
1407                  */
1408                 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1409                         err = jbd2_log_wait_commit(journal, tid);
1410         } else {
1411                 spin_unlock(&transaction->t_handle_lock);
1412                 spin_unlock(&journal->j_state_lock);
1413         }
1414
1415         jbd_free_handle(handle);
1416         return err;
1417 }
1418
1419 /**int jbd2_journal_force_commit() - force any uncommitted transactions
1420  * @journal: journal to force
1421  *
1422  * For synchronous operations: force any uncommitted transactions
1423  * to disk.  May seem kludgy, but it reuses all the handle batching
1424  * code in a very simple manner.
1425  */
1426 int jbd2_journal_force_commit(journal_t *journal)
1427 {
1428         handle_t *handle;
1429         int ret;
1430
1431         handle = jbd2_journal_start(journal, 1);
1432         if (IS_ERR(handle)) {
1433                 ret = PTR_ERR(handle);
1434         } else {
1435                 handle->h_sync = 1;
1436                 ret = jbd2_journal_stop(handle);
1437         }
1438         return ret;
1439 }
1440
1441 /*
1442  *
1443  * List management code snippets: various functions for manipulating the
1444  * transaction buffer lists.
1445  *
1446  */
1447
1448 /*
1449  * Append a buffer to a transaction list, given the transaction's list head
1450  * pointer.
1451  *
1452  * j_list_lock is held.
1453  *
1454  * jbd_lock_bh_state(jh2bh(jh)) is held.
1455  */
1456
1457 static inline void
1458 __blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1459 {
1460         if (!*list) {
1461                 jh->b_tnext = jh->b_tprev = jh;
1462                 *list = jh;
1463         } else {
1464                 /* Insert at the tail of the list to preserve order */
1465                 struct journal_head *first = *list, *last = first->b_tprev;
1466                 jh->b_tprev = last;
1467                 jh->b_tnext = first;
1468                 last->b_tnext = first->b_tprev = jh;
1469         }
1470 }
1471
1472 /*
1473  * Remove a buffer from a transaction list, given the transaction's list
1474  * head pointer.
1475  *
1476  * Called with j_list_lock held, and the journal may not be locked.
1477  *
1478  * jbd_lock_bh_state(jh2bh(jh)) is held.
1479  */
1480
1481 static inline void
1482 __blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1483 {
1484         if (*list == jh) {
1485                 *list = jh->b_tnext;
1486                 if (*list == jh)
1487                         *list = NULL;
1488         }
1489         jh->b_tprev->b_tnext = jh->b_tnext;
1490         jh->b_tnext->b_tprev = jh->b_tprev;
1491 }
1492
1493 /*
1494  * Remove a buffer from the appropriate transaction list.
1495  *
1496  * Note that this function can *change* the value of
1497  * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
1498  * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list.  If the caller
1499  * is holding onto a copy of one of thee pointers, it could go bad.
1500  * Generally the caller needs to re-read the pointer from the transaction_t.
1501  *
1502  * Called under j_list_lock.  The journal may not be locked.
1503  */
1504 void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
1505 {
1506         struct journal_head **list = NULL;
1507         transaction_t *transaction;
1508         struct buffer_head *bh = jh2bh(jh);
1509
1510         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1511         transaction = jh->b_transaction;
1512         if (transaction)
1513                 assert_spin_locked(&transaction->t_journal->j_list_lock);
1514
1515         J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1516         if (jh->b_jlist != BJ_None)
1517                 J_ASSERT_JH(jh, transaction != 0);
1518
1519         switch (jh->b_jlist) {
1520         case BJ_None:
1521                 return;
1522         case BJ_SyncData:
1523                 list = &transaction->t_sync_datalist;
1524                 break;
1525         case BJ_Metadata:
1526                 transaction->t_nr_buffers--;
1527                 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1528                 list = &transaction->t_buffers;
1529                 break;
1530         case BJ_Forget:
1531                 list = &transaction->t_forget;
1532                 break;
1533         case BJ_IO:
1534                 list = &transaction->t_iobuf_list;
1535                 break;
1536         case BJ_Shadow:
1537                 list = &transaction->t_shadow_list;
1538                 break;
1539         case BJ_LogCtl:
1540                 list = &transaction->t_log_list;
1541                 break;
1542         case BJ_Reserved:
1543                 list = &transaction->t_reserved_list;
1544                 break;
1545         case BJ_Locked:
1546                 list = &transaction->t_locked_list;
1547                 break;
1548         }
1549
1550         __blist_del_buffer(list, jh);
1551         jh->b_jlist = BJ_None;
1552         if (test_clear_buffer_jbddirty(bh))
1553                 mark_buffer_dirty(bh);  /* Expose it to the VM */
1554 }
1555
1556 void __jbd2_journal_unfile_buffer(struct journal_head *jh)
1557 {
1558         __jbd2_journal_temp_unlink_buffer(jh);
1559         jh->b_transaction = NULL;
1560 }
1561
1562 void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1563 {
1564         jbd_lock_bh_state(jh2bh(jh));
1565         spin_lock(&journal->j_list_lock);
1566         __jbd2_journal_unfile_buffer(jh);
1567         spin_unlock(&journal->j_list_lock);
1568         jbd_unlock_bh_state(jh2bh(jh));
1569 }
1570
1571 /*
1572  * Called from jbd2_journal_try_to_free_buffers().
1573  *
1574  * Called under jbd_lock_bh_state(bh)
1575  */
1576 static void
1577 __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1578 {
1579         struct journal_head *jh;
1580
1581         jh = bh2jh(bh);
1582
1583         if (buffer_locked(bh) || buffer_dirty(bh))
1584                 goto out;
1585
1586         if (jh->b_next_transaction != 0)
1587                 goto out;
1588
1589         spin_lock(&journal->j_list_lock);
1590         if (jh->b_transaction != 0 && jh->b_cp_transaction == 0) {
1591                 if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
1592                         /* A written-back ordered data buffer */
1593                         JBUFFER_TRACE(jh, "release data");
1594                         __jbd2_journal_unfile_buffer(jh);
1595                         jbd2_journal_remove_journal_head(bh);
1596                         __brelse(bh);
1597                 }
1598         } else if (jh->b_cp_transaction != 0 && jh->b_transaction == 0) {
1599                 /* written-back checkpointed metadata buffer */
1600                 if (jh->b_jlist == BJ_None) {
1601                         JBUFFER_TRACE(jh, "remove from checkpoint list");
1602                         __jbd2_journal_remove_checkpoint(jh);
1603                         jbd2_journal_remove_journal_head(bh);
1604                         __brelse(bh);
1605                 }
1606         }
1607         spin_unlock(&journal->j_list_lock);
1608 out:
1609         return;
1610 }
1611
1612
1613 /**
1614  * int jbd2_journal_try_to_free_buffers() - try to free page buffers.
1615  * @journal: journal for operation
1616  * @page: to try and free
1617  * @unused_gfp_mask: unused
1618  *
1619  *
1620  * For all the buffers on this page,
1621  * if they are fully written out ordered data, move them onto BUF_CLEAN
1622  * so try_to_free_buffers() can reap them.
1623  *
1624  * This function returns non-zero if we wish try_to_free_buffers()
1625  * to be called. We do this if the page is releasable by try_to_free_buffers().
1626  * We also do it if the page has locked or dirty buffers and the caller wants
1627  * us to perform sync or async writeout.
1628  *
1629  * This complicates JBD locking somewhat.  We aren't protected by the
1630  * BKL here.  We wish to remove the buffer from its committing or
1631  * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
1632  *
1633  * This may *change* the value of transaction_t->t_datalist, so anyone
1634  * who looks at t_datalist needs to lock against this function.
1635  *
1636  * Even worse, someone may be doing a jbd2_journal_dirty_data on this
1637  * buffer.  So we need to lock against that.  jbd2_journal_dirty_data()
1638  * will come out of the lock with the buffer dirty, which makes it
1639  * ineligible for release here.
1640  *
1641  * Who else is affected by this?  hmm...  Really the only contender
1642  * is do_get_write_access() - it could be looking at the buffer while
1643  * journal_try_to_free_buffer() is changing its state.  But that
1644  * cannot happen because we never reallocate freed data as metadata
1645  * while the data is part of a transaction.  Yes?
1646  */
1647 int jbd2_journal_try_to_free_buffers(journal_t *journal,
1648                                 struct page *page, gfp_t unused_gfp_mask)
1649 {
1650         struct buffer_head *head;
1651         struct buffer_head *bh;
1652         int ret = 0;
1653
1654         J_ASSERT(PageLocked(page));
1655
1656         head = page_buffers(page);
1657         bh = head;
1658         do {
1659                 struct journal_head *jh;
1660
1661                 /*
1662                  * We take our own ref against the journal_head here to avoid
1663                  * having to add tons of locking around each instance of
1664                  * jbd2_journal_remove_journal_head() and jbd2_journal_put_journal_head().
1665                  */
1666                 jh = jbd2_journal_grab_journal_head(bh);
1667                 if (!jh)
1668                         continue;
1669
1670                 jbd_lock_bh_state(bh);
1671                 __journal_try_to_free_buffer(journal, bh);
1672                 jbd2_journal_put_journal_head(jh);
1673                 jbd_unlock_bh_state(bh);
1674                 if (buffer_jbd(bh))
1675                         goto busy;
1676         } while ((bh = bh->b_this_page) != head);
1677         ret = try_to_free_buffers(page);
1678 busy:
1679         return ret;
1680 }
1681
1682 /*
1683  * This buffer is no longer needed.  If it is on an older transaction's
1684  * checkpoint list we need to record it on this transaction's forget list
1685  * to pin this buffer (and hence its checkpointing transaction) down until
1686  * this transaction commits.  If the buffer isn't on a checkpoint list, we
1687  * release it.
1688  * Returns non-zero if JBD no longer has an interest in the buffer.
1689  *
1690  * Called under j_list_lock.
1691  *
1692  * Called under jbd_lock_bh_state(bh).
1693  */
1694 static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1695 {
1696         int may_free = 1;
1697         struct buffer_head *bh = jh2bh(jh);
1698
1699         __jbd2_journal_unfile_buffer(jh);
1700
1701         if (jh->b_cp_transaction) {
1702                 JBUFFER_TRACE(jh, "on running+cp transaction");
1703                 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1704                 clear_buffer_jbddirty(bh);
1705                 may_free = 0;
1706         } else {
1707                 JBUFFER_TRACE(jh, "on running transaction");
1708                 jbd2_journal_remove_journal_head(bh);
1709                 __brelse(bh);
1710         }
1711         return may_free;
1712 }
1713
1714 /*
1715  * jbd2_journal_invalidatepage
1716  *
1717  * This code is tricky.  It has a number of cases to deal with.
1718  *
1719  * There are two invariants which this code relies on:
1720  *
1721  * i_size must be updated on disk before we start calling invalidatepage on the
1722  * data.
1723  *
1724  *  This is done in ext3 by defining an ext3_setattr method which
1725  *  updates i_size before truncate gets going.  By maintaining this
1726  *  invariant, we can be sure that it is safe to throw away any buffers
1727  *  attached to the current transaction: once the transaction commits,
1728  *  we know that the data will not be needed.
1729  *
1730  *  Note however that we can *not* throw away data belonging to the
1731  *  previous, committing transaction!
1732  *
1733  * Any disk blocks which *are* part of the previous, committing
1734  * transaction (and which therefore cannot be discarded immediately) are
1735  * not going to be reused in the new running transaction
1736  *
1737  *  The bitmap committed_data images guarantee this: any block which is
1738  *  allocated in one transaction and removed in the next will be marked
1739  *  as in-use in the committed_data bitmap, so cannot be reused until
1740  *  the next transaction to delete the block commits.  This means that
1741  *  leaving committing buffers dirty is quite safe: the disk blocks
1742  *  cannot be reallocated to a different file and so buffer aliasing is
1743  *  not possible.
1744  *
1745  *
1746  * The above applies mainly to ordered data mode.  In writeback mode we
1747  * don't make guarantees about the order in which data hits disk --- in
1748  * particular we don't guarantee that new dirty data is flushed before
1749  * transaction commit --- so it is always safe just to discard data
1750  * immediately in that mode.  --sct
1751  */
1752
1753 /*
1754  * The journal_unmap_buffer helper function returns zero if the buffer
1755  * concerned remains pinned as an anonymous buffer belonging to an older
1756  * transaction.
1757  *
1758  * We're outside-transaction here.  Either or both of j_running_transaction
1759  * and j_committing_transaction may be NULL.
1760  */
1761 static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1762 {
1763         transaction_t *transaction;
1764         struct journal_head *jh;
1765         int may_free = 1;
1766         int ret;
1767
1768         BUFFER_TRACE(bh, "entry");
1769
1770         /*
1771          * It is safe to proceed here without the j_list_lock because the
1772          * buffers cannot be stolen by try_to_free_buffers as long as we are
1773          * holding the page lock. --sct
1774          */
1775
1776         if (!buffer_jbd(bh))
1777                 goto zap_buffer_unlocked;
1778
1779         spin_lock(&journal->j_state_lock);
1780         jbd_lock_bh_state(bh);
1781         spin_lock(&journal->j_list_lock);
1782
1783         jh = jbd2_journal_grab_journal_head(bh);
1784         if (!jh)
1785                 goto zap_buffer_no_jh;
1786
1787         transaction = jh->b_transaction;
1788         if (transaction == NULL) {
1789                 /* First case: not on any transaction.  If it
1790                  * has no checkpoint link, then we can zap it:
1791                  * it's a writeback-mode buffer so we don't care
1792                  * if it hits disk safely. */
1793                 if (!jh->b_cp_transaction) {
1794                         JBUFFER_TRACE(jh, "not on any transaction: zap");
1795                         goto zap_buffer;
1796                 }
1797
1798                 if (!buffer_dirty(bh)) {
1799                         /* bdflush has written it.  We can drop it now */
1800                         goto zap_buffer;
1801                 }
1802
1803                 /* OK, it must be in the journal but still not
1804                  * written fully to disk: it's metadata or
1805                  * journaled data... */
1806
1807                 if (journal->j_running_transaction) {
1808                         /* ... and once the current transaction has
1809                          * committed, the buffer won't be needed any
1810                          * longer. */
1811                         JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1812                         ret = __dispose_buffer(jh,
1813                                         journal->j_running_transaction);
1814                         jbd2_journal_put_journal_head(jh);
1815                         spin_unlock(&journal->j_list_lock);
1816                         jbd_unlock_bh_state(bh);
1817                         spin_unlock(&journal->j_state_lock);
1818                         return ret;
1819                 } else {
1820                         /* There is no currently-running transaction. So the
1821                          * orphan record which we wrote for this file must have
1822                          * passed into commit.  We must attach this buffer to
1823                          * the committing transaction, if it exists. */
1824                         if (journal->j_committing_transaction) {
1825                                 JBUFFER_TRACE(jh, "give to committing trans");
1826                                 ret = __dispose_buffer(jh,
1827                                         journal->j_committing_transaction);
1828                                 jbd2_journal_put_journal_head(jh);
1829                                 spin_unlock(&journal->j_list_lock);
1830                                 jbd_unlock_bh_state(bh);
1831                                 spin_unlock(&journal->j_state_lock);
1832                                 return ret;
1833                         } else {
1834                                 /* The orphan record's transaction has
1835                                  * committed.  We can cleanse this buffer */
1836                                 clear_buffer_jbddirty(bh);
1837                                 goto zap_buffer;
1838                         }
1839                 }
1840         } else if (transaction == journal->j_committing_transaction) {
1841                 JBUFFER_TRACE(jh, "on committing transaction");
1842                 if (jh->b_jlist == BJ_Locked) {
1843                         /*
1844                          * The buffer is on the committing transaction's locked
1845                          * list.  We have the buffer locked, so I/O has
1846                          * completed.  So we can nail the buffer now.
1847                          */
1848                         may_free = __dispose_buffer(jh, transaction);
1849                         goto zap_buffer;
1850                 }
1851                 /*
1852                  * If it is committing, we simply cannot touch it.  We
1853                  * can remove it's next_transaction pointer from the
1854                  * running transaction if that is set, but nothing
1855                  * else. */
1856                 set_buffer_freed(bh);
1857                 if (jh->b_next_transaction) {
1858                         J_ASSERT(jh->b_next_transaction ==
1859                                         journal->j_running_transaction);
1860                         jh->b_next_transaction = NULL;
1861                 }
1862                 jbd2_journal_put_journal_head(jh);
1863                 spin_unlock(&journal->j_list_lock);
1864                 jbd_unlock_bh_state(bh);
1865                 spin_unlock(&journal->j_state_lock);
1866                 return 0;
1867         } else {
1868                 /* Good, the buffer belongs to the running transaction.
1869                  * We are writing our own transaction's data, not any
1870                  * previous one's, so it is safe to throw it away
1871                  * (remember that we expect the filesystem to have set
1872                  * i_size already for this truncate so recovery will not
1873                  * expose the disk blocks we are discarding here.) */
1874                 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
1875                 JBUFFER_TRACE(jh, "on running transaction");
1876                 may_free = __dispose_buffer(jh, transaction);
1877         }
1878
1879 zap_buffer:
1880         jbd2_journal_put_journal_head(jh);
1881 zap_buffer_no_jh:
1882         spin_unlock(&journal->j_list_lock);
1883         jbd_unlock_bh_state(bh);
1884         spin_unlock(&journal->j_state_lock);
1885 zap_buffer_unlocked:
1886         clear_buffer_dirty(bh);
1887         J_ASSERT_BH(bh, !buffer_jbddirty(bh));
1888         clear_buffer_mapped(bh);
1889         clear_buffer_req(bh);
1890         clear_buffer_new(bh);
1891         bh->b_bdev = NULL;
1892         return may_free;
1893 }
1894
1895 /**
1896  * void jbd2_journal_invalidatepage()
1897  * @journal: journal to use for flush...
1898  * @page:    page to flush
1899  * @offset:  length of page to invalidate.
1900  *
1901  * Reap page buffers containing data after offset in page.
1902  *
1903  */
1904 void jbd2_journal_invalidatepage(journal_t *journal,
1905                       struct page *page,
1906                       unsigned long offset)
1907 {
1908         struct buffer_head *head, *bh, *next;
1909         unsigned int curr_off = 0;
1910         int may_free = 1;
1911
1912         if (!PageLocked(page))
1913                 BUG();
1914         if (!page_has_buffers(page))
1915                 return;
1916
1917         /* We will potentially be playing with lists other than just the
1918          * data lists (especially for journaled data mode), so be
1919          * cautious in our locking. */
1920
1921         head = bh = page_buffers(page);
1922         do {
1923                 unsigned int next_off = curr_off + bh->b_size;
1924                 next = bh->b_this_page;
1925
1926                 if (offset <= curr_off) {
1927                         /* This block is wholly outside the truncation point */
1928                         lock_buffer(bh);
1929                         may_free &= journal_unmap_buffer(journal, bh);
1930                         unlock_buffer(bh);
1931                 }
1932                 curr_off = next_off;
1933                 bh = next;
1934
1935         } while (bh != head);
1936
1937         if (!offset) {
1938                 if (may_free && try_to_free_buffers(page))
1939                         J_ASSERT(!page_has_buffers(page));
1940         }
1941 }
1942
1943 /*
1944  * File a buffer on the given transaction list.
1945  */
1946 void __jbd2_journal_file_buffer(struct journal_head *jh,
1947                         transaction_t *transaction, int jlist)
1948 {
1949         struct journal_head **list = NULL;
1950         int was_dirty = 0;
1951         struct buffer_head *bh = jh2bh(jh);
1952
1953         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1954         assert_spin_locked(&transaction->t_journal->j_list_lock);
1955
1956         J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1957         J_ASSERT_JH(jh, jh->b_transaction == transaction ||
1958                                 jh->b_transaction == 0);
1959
1960         if (jh->b_transaction && jh->b_jlist == jlist)
1961                 return;
1962
1963         /* The following list of buffer states needs to be consistent
1964          * with __jbd_unexpected_dirty_buffer()'s handling of dirty
1965          * state. */
1966
1967         if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
1968             jlist == BJ_Shadow || jlist == BJ_Forget) {
1969                 if (test_clear_buffer_dirty(bh) ||
1970                     test_clear_buffer_jbddirty(bh))
1971                         was_dirty = 1;
1972         }
1973
1974         if (jh->b_transaction)
1975                 __jbd2_journal_temp_unlink_buffer(jh);
1976         jh->b_transaction = transaction;
1977
1978         switch (jlist) {
1979         case BJ_None:
1980                 J_ASSERT_JH(jh, !jh->b_committed_data);
1981                 J_ASSERT_JH(jh, !jh->b_frozen_data);
1982                 return;
1983         case BJ_SyncData:
1984                 list = &transaction->t_sync_datalist;
1985                 break;
1986         case BJ_Metadata:
1987                 transaction->t_nr_buffers++;
1988                 list = &transaction->t_buffers;
1989                 break;
1990         case BJ_Forget:
1991                 list = &transaction->t_forget;
1992                 break;
1993         case BJ_IO:
1994                 list = &transaction->t_iobuf_list;
1995                 break;
1996         case BJ_Shadow:
1997                 list = &transaction->t_shadow_list;
1998                 break;
1999         case BJ_LogCtl:
2000                 list = &transaction->t_log_list;
2001                 break;
2002         case BJ_Reserved:
2003                 list = &transaction->t_reserved_list;
2004                 break;
2005         case BJ_Locked:
2006                 list =  &transaction->t_locked_list;
2007                 break;
2008         }
2009
2010         __blist_add_buffer(list, jh);
2011         jh->b_jlist = jlist;
2012
2013         if (was_dirty)
2014                 set_buffer_jbddirty(bh);
2015 }
2016
2017 void jbd2_journal_file_buffer(struct journal_head *jh,
2018                                 transaction_t *transaction, int jlist)
2019 {
2020         jbd_lock_bh_state(jh2bh(jh));
2021         spin_lock(&transaction->t_journal->j_list_lock);
2022         __jbd2_journal_file_buffer(jh, transaction, jlist);
2023         spin_unlock(&transaction->t_journal->j_list_lock);
2024         jbd_unlock_bh_state(jh2bh(jh));
2025 }
2026
2027 /*
2028  * Remove a buffer from its current buffer list in preparation for
2029  * dropping it from its current transaction entirely.  If the buffer has
2030  * already started to be used by a subsequent transaction, refile the
2031  * buffer on that transaction's metadata list.
2032  *
2033  * Called under journal->j_list_lock
2034  *
2035  * Called under jbd_lock_bh_state(jh2bh(jh))
2036  */
2037 void __jbd2_journal_refile_buffer(struct journal_head *jh)
2038 {
2039         int was_dirty;
2040         struct buffer_head *bh = jh2bh(jh);
2041
2042         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2043         if (jh->b_transaction)
2044                 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2045
2046         /* If the buffer is now unused, just drop it. */
2047         if (jh->b_next_transaction == NULL) {
2048                 __jbd2_journal_unfile_buffer(jh);
2049                 return;
2050         }
2051
2052         /*
2053          * It has been modified by a later transaction: add it to the new
2054          * transaction's metadata list.
2055          */
2056
2057         was_dirty = test_clear_buffer_jbddirty(bh);
2058         __jbd2_journal_temp_unlink_buffer(jh);
2059         jh->b_transaction = jh->b_next_transaction;
2060         jh->b_next_transaction = NULL;
2061         __jbd2_journal_file_buffer(jh, jh->b_transaction,
2062                                 was_dirty ? BJ_Metadata : BJ_Reserved);
2063         J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2064
2065         if (was_dirty)
2066                 set_buffer_jbddirty(bh);
2067 }
2068
2069 /*
2070  * For the unlocked version of this call, also make sure that any
2071  * hanging journal_head is cleaned up if necessary.
2072  *
2073  * __jbd2_journal_refile_buffer is usually called as part of a single locked
2074  * operation on a buffer_head, in which the caller is probably going to
2075  * be hooking the journal_head onto other lists.  In that case it is up
2076  * to the caller to remove the journal_head if necessary.  For the
2077  * unlocked jbd2_journal_refile_buffer call, the caller isn't going to be
2078  * doing anything else to the buffer so we need to do the cleanup
2079  * ourselves to avoid a jh leak.
2080  *
2081  * *** The journal_head may be freed by this call! ***
2082  */
2083 void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2084 {
2085         struct buffer_head *bh = jh2bh(jh);
2086
2087         jbd_lock_bh_state(bh);
2088         spin_lock(&journal->j_list_lock);
2089
2090         __jbd2_journal_refile_buffer(jh);
2091         jbd_unlock_bh_state(bh);
2092         jbd2_journal_remove_journal_head(bh);
2093
2094         spin_unlock(&journal->j_list_lock);
2095         __brelse(bh);
2096 }