Merge branch 'upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/linville...
[linux-2.6] / 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 = 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
63         return transaction;
64 }
65
66 /*
67  * Handle management.
68  *
69  * A handle_t is an object which represents a single atomic update to a
70  * filesystem, and which tracks all of the modifications which form part
71  * of that one update.
72  */
73
74 /*
75  * start_this_handle: Given a handle, deal with any locking or stalling
76  * needed to make sure that there is enough journal space for the handle
77  * to begin.  Attach the handle to a transaction and set up the
78  * transaction's buffer credits.
79  */
80
81 static int start_this_handle(journal_t *journal, handle_t *handle)
82 {
83         transaction_t *transaction;
84         int needed;
85         int nblocks = handle->h_buffer_credits;
86         transaction_t *new_transaction = NULL;
87         int ret = 0;
88
89         if (nblocks > journal->j_max_transaction_buffers) {
90                 printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
91                        current->comm, nblocks,
92                        journal->j_max_transaction_buffers);
93                 ret = -ENOSPC;
94                 goto out;
95         }
96
97 alloc_transaction:
98         if (!journal->j_running_transaction) {
99                 new_transaction = jbd_kmalloc(sizeof(*new_transaction),
100                                                 GFP_NOFS);
101                 if (!new_transaction) {
102                         ret = -ENOMEM;
103                         goto out;
104                 }
105                 memset(new_transaction, 0, sizeof(*new_transaction));
106         }
107
108         jbd_debug(3, "New handle %p going live.\n", handle);
109
110 repeat:
111
112         /*
113          * We need to hold j_state_lock until t_updates has been incremented,
114          * for proper journal barrier handling
115          */
116         spin_lock(&journal->j_state_lock);
117 repeat_locked:
118         if (is_journal_aborted(journal) ||
119             (journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) {
120                 spin_unlock(&journal->j_state_lock);
121                 ret = -EROFS;
122                 goto out;
123         }
124
125         /* Wait on the journal's transaction barrier if necessary */
126         if (journal->j_barrier_count) {
127                 spin_unlock(&journal->j_state_lock);
128                 wait_event(journal->j_wait_transaction_locked,
129                                 journal->j_barrier_count == 0);
130                 goto repeat;
131         }
132
133         if (!journal->j_running_transaction) {
134                 if (!new_transaction) {
135                         spin_unlock(&journal->j_state_lock);
136                         goto alloc_transaction;
137                 }
138                 jbd2_get_transaction(journal, new_transaction);
139                 new_transaction = NULL;
140         }
141
142         transaction = journal->j_running_transaction;
143
144         /*
145          * If the current transaction is locked down for commit, wait for the
146          * lock to be released.
147          */
148         if (transaction->t_state == T_LOCKED) {
149                 DEFINE_WAIT(wait);
150
151                 prepare_to_wait(&journal->j_wait_transaction_locked,
152                                         &wait, TASK_UNINTERRUPTIBLE);
153                 spin_unlock(&journal->j_state_lock);
154                 schedule();
155                 finish_wait(&journal->j_wait_transaction_locked, &wait);
156                 goto repeat;
157         }
158
159         /*
160          * If there is not enough space left in the log to write all potential
161          * buffers requested by this operation, we need to stall pending a log
162          * checkpoint to free some more log space.
163          */
164         spin_lock(&transaction->t_handle_lock);
165         needed = transaction->t_outstanding_credits + nblocks;
166
167         if (needed > journal->j_max_transaction_buffers) {
168                 /*
169                  * If the current transaction is already too large, then start
170                  * to commit it: we can then go back and attach this handle to
171                  * a new transaction.
172                  */
173                 DEFINE_WAIT(wait);
174
175                 jbd_debug(2, "Handle %p starting new commit...\n", handle);
176                 spin_unlock(&transaction->t_handle_lock);
177                 prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
178                                 TASK_UNINTERRUPTIBLE);
179                 __jbd2_log_start_commit(journal, transaction->t_tid);
180                 spin_unlock(&journal->j_state_lock);
181                 schedule();
182                 finish_wait(&journal->j_wait_transaction_locked, &wait);
183                 goto repeat;
184         }
185
186         /*
187          * The commit code assumes that it can get enough log space
188          * without forcing a checkpoint.  This is *critical* for
189          * correctness: a checkpoint of a buffer which is also
190          * associated with a committing transaction creates a deadlock,
191          * so commit simply cannot force through checkpoints.
192          *
193          * We must therefore ensure the necessary space in the journal
194          * *before* starting to dirty potentially checkpointed buffers
195          * in the new transaction.
196          *
197          * The worst part is, any transaction currently committing can
198          * reduce the free space arbitrarily.  Be careful to account for
199          * those buffers when checkpointing.
200          */
201
202         /*
203          * @@@ AKPM: This seems rather over-defensive.  We're giving commit
204          * a _lot_ of headroom: 1/4 of the journal plus the size of
205          * the committing transaction.  Really, we only need to give it
206          * committing_transaction->t_outstanding_credits plus "enough" for
207          * the log control blocks.
208          * Also, this test is inconsitent with the matching one in
209          * jbd2_journal_extend().
210          */
211         if (__jbd2_log_space_left(journal) < jbd_space_needed(journal)) {
212                 jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
213                 spin_unlock(&transaction->t_handle_lock);
214                 __jbd2_log_wait_for_space(journal);
215                 goto repeat_locked;
216         }
217
218         /* OK, account for the buffers that this operation expects to
219          * use and add the handle to the running transaction. */
220
221         handle->h_transaction = transaction;
222         transaction->t_outstanding_credits += nblocks;
223         transaction->t_updates++;
224         transaction->t_handle_count++;
225         jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
226                   handle, nblocks, transaction->t_outstanding_credits,
227                   __jbd2_log_space_left(journal));
228         spin_unlock(&transaction->t_handle_lock);
229         spin_unlock(&journal->j_state_lock);
230 out:
231         if (unlikely(new_transaction))          /* It's usually NULL */
232                 kfree(new_transaction);
233         return ret;
234 }
235
236 /* Allocate a new handle.  This should probably be in a slab... */
237 static handle_t *new_handle(int nblocks)
238 {
239         handle_t *handle = jbd_alloc_handle(GFP_NOFS);
240         if (!handle)
241                 return NULL;
242         memset(handle, 0, sizeof(*handle));
243         handle->h_buffer_credits = nblocks;
244         handle->h_ref = 1;
245
246         return handle;
247 }
248
249 /**
250  * handle_t *jbd2_journal_start() - Obtain a new handle.
251  * @journal: Journal to start transaction on.
252  * @nblocks: number of block buffer we might modify
253  *
254  * We make sure that the transaction can guarantee at least nblocks of
255  * modified buffers in the log.  We block until the log can guarantee
256  * that much space.
257  *
258  * This function is visible to journal users (like ext3fs), so is not
259  * called with the journal already locked.
260  *
261  * Return a pointer to a newly allocated handle, or NULL on failure
262  */
263 handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
264 {
265         handle_t *handle = journal_current_handle();
266         int err;
267
268         if (!journal)
269                 return ERR_PTR(-EROFS);
270
271         if (handle) {
272                 J_ASSERT(handle->h_transaction->t_journal == journal);
273                 handle->h_ref++;
274                 return handle;
275         }
276
277         handle = new_handle(nblocks);
278         if (!handle)
279                 return ERR_PTR(-ENOMEM);
280
281         current->journal_info = handle;
282
283         err = start_this_handle(journal, handle);
284         if (err < 0) {
285                 jbd_free_handle(handle);
286                 current->journal_info = NULL;
287                 handle = ERR_PTR(err);
288         }
289         return handle;
290 }
291
292 /**
293  * int jbd2_journal_extend() - extend buffer credits.
294  * @handle:  handle to 'extend'
295  * @nblocks: nr blocks to try to extend by.
296  *
297  * Some transactions, such as large extends and truncates, can be done
298  * atomically all at once or in several stages.  The operation requests
299  * a credit for a number of buffer modications in advance, but can
300  * extend its credit if it needs more.
301  *
302  * jbd2_journal_extend tries to give the running handle more buffer credits.
303  * It does not guarantee that allocation - this is a best-effort only.
304  * The calling process MUST be able to deal cleanly with a failure to
305  * extend here.
306  *
307  * Return 0 on success, non-zero on failure.
308  *
309  * return code < 0 implies an error
310  * return code > 0 implies normal transaction-full status.
311  */
312 int jbd2_journal_extend(handle_t *handle, int nblocks)
313 {
314         transaction_t *transaction = handle->h_transaction;
315         journal_t *journal = transaction->t_journal;
316         int result;
317         int wanted;
318
319         result = -EIO;
320         if (is_handle_aborted(handle))
321                 goto out;
322
323         result = 1;
324
325         spin_lock(&journal->j_state_lock);
326
327         /* Don't extend a locked-down transaction! */
328         if (handle->h_transaction->t_state != T_RUNNING) {
329                 jbd_debug(3, "denied handle %p %d blocks: "
330                           "transaction not running\n", handle, nblocks);
331                 goto error_out;
332         }
333
334         spin_lock(&transaction->t_handle_lock);
335         wanted = transaction->t_outstanding_credits + nblocks;
336
337         if (wanted > journal->j_max_transaction_buffers) {
338                 jbd_debug(3, "denied handle %p %d blocks: "
339                           "transaction too large\n", handle, nblocks);
340                 goto unlock;
341         }
342
343         if (wanted > __jbd2_log_space_left(journal)) {
344                 jbd_debug(3, "denied handle %p %d blocks: "
345                           "insufficient log space\n", handle, nblocks);
346                 goto unlock;
347         }
348
349         handle->h_buffer_credits += nblocks;
350         transaction->t_outstanding_credits += nblocks;
351         result = 0;
352
353         jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
354 unlock:
355         spin_unlock(&transaction->t_handle_lock);
356 error_out:
357         spin_unlock(&journal->j_state_lock);
358 out:
359         return result;
360 }
361
362
363 /**
364  * int jbd2_journal_restart() - restart a handle .
365  * @handle:  handle to restart
366  * @nblocks: nr credits requested
367  *
368  * Restart a handle for a multi-transaction filesystem
369  * operation.
370  *
371  * If the jbd2_journal_extend() call above fails to grant new buffer credits
372  * to a running handle, a call to jbd2_journal_restart will commit the
373  * handle's transaction so far and reattach the handle to a new
374  * transaction capabable of guaranteeing the requested number of
375  * credits.
376  */
377
378 int jbd2_journal_restart(handle_t *handle, int nblocks)
379 {
380         transaction_t *transaction = handle->h_transaction;
381         journal_t *journal = transaction->t_journal;
382         int ret;
383
384         /* If we've had an abort of any type, don't even think about
385          * actually doing the restart! */
386         if (is_handle_aborted(handle))
387                 return 0;
388
389         /*
390          * First unlink the handle from its current transaction, and start the
391          * commit on that.
392          */
393         J_ASSERT(transaction->t_updates > 0);
394         J_ASSERT(journal_current_handle() == handle);
395
396         spin_lock(&journal->j_state_lock);
397         spin_lock(&transaction->t_handle_lock);
398         transaction->t_outstanding_credits -= handle->h_buffer_credits;
399         transaction->t_updates--;
400
401         if (!transaction->t_updates)
402                 wake_up(&journal->j_wait_updates);
403         spin_unlock(&transaction->t_handle_lock);
404
405         jbd_debug(2, "restarting handle %p\n", handle);
406         __jbd2_log_start_commit(journal, transaction->t_tid);
407         spin_unlock(&journal->j_state_lock);
408
409         handle->h_buffer_credits = nblocks;
410         ret = start_this_handle(journal, handle);
411         return ret;
412 }
413
414
415 /**
416  * void jbd2_journal_lock_updates () - establish a transaction barrier.
417  * @journal:  Journal to establish a barrier on.
418  *
419  * This locks out any further updates from being started, and blocks
420  * until all existing updates have completed, returning only once the
421  * journal is in a quiescent state with no updates running.
422  *
423  * The journal lock should not be held on entry.
424  */
425 void jbd2_journal_lock_updates(journal_t *journal)
426 {
427         DEFINE_WAIT(wait);
428
429         spin_lock(&journal->j_state_lock);
430         ++journal->j_barrier_count;
431
432         /* Wait until there are no running updates */
433         while (1) {
434                 transaction_t *transaction = journal->j_running_transaction;
435
436                 if (!transaction)
437                         break;
438
439                 spin_lock(&transaction->t_handle_lock);
440                 if (!transaction->t_updates) {
441                         spin_unlock(&transaction->t_handle_lock);
442                         break;
443                 }
444                 prepare_to_wait(&journal->j_wait_updates, &wait,
445                                 TASK_UNINTERRUPTIBLE);
446                 spin_unlock(&transaction->t_handle_lock);
447                 spin_unlock(&journal->j_state_lock);
448                 schedule();
449                 finish_wait(&journal->j_wait_updates, &wait);
450                 spin_lock(&journal->j_state_lock);
451         }
452         spin_unlock(&journal->j_state_lock);
453
454         /*
455          * We have now established a barrier against other normal updates, but
456          * we also need to barrier against other jbd2_journal_lock_updates() calls
457          * to make sure that we serialise special journal-locked operations
458          * too.
459          */
460         mutex_lock(&journal->j_barrier);
461 }
462
463 /**
464  * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier
465  * @journal:  Journal to release the barrier on.
466  *
467  * Release a transaction barrier obtained with jbd2_journal_lock_updates().
468  *
469  * Should be called without the journal lock held.
470  */
471 void jbd2_journal_unlock_updates (journal_t *journal)
472 {
473         J_ASSERT(journal->j_barrier_count != 0);
474
475         mutex_unlock(&journal->j_barrier);
476         spin_lock(&journal->j_state_lock);
477         --journal->j_barrier_count;
478         spin_unlock(&journal->j_state_lock);
479         wake_up(&journal->j_wait_transaction_locked);
480 }
481
482 /*
483  * Report any unexpected dirty buffers which turn up.  Normally those
484  * indicate an error, but they can occur if the user is running (say)
485  * tune2fs to modify the live filesystem, so we need the option of
486  * continuing as gracefully as possible.  #
487  *
488  * The caller should already hold the journal lock and
489  * j_list_lock spinlock: most callers will need those anyway
490  * in order to probe the buffer's journaling state safely.
491  */
492 static void jbd_unexpected_dirty_buffer(struct journal_head *jh)
493 {
494         int jlist;
495
496         /* If this buffer is one which might reasonably be dirty
497          * --- ie. data, or not part of this journal --- then
498          * we're OK to leave it alone, but otherwise we need to
499          * move the dirty bit to the journal's own internal
500          * JBDDirty bit. */
501         jlist = jh->b_jlist;
502
503         if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
504             jlist == BJ_Shadow || jlist == BJ_Forget) {
505                 struct buffer_head *bh = jh2bh(jh);
506
507                 if (test_clear_buffer_dirty(bh))
508                         set_buffer_jbddirty(bh);
509         }
510 }
511
512 /*
513  * If the buffer is already part of the current transaction, then there
514  * is nothing we need to do.  If it is already part of a prior
515  * transaction which we are still committing to disk, then we need to
516  * make sure that we do not overwrite the old copy: we do copy-out to
517  * preserve the copy going to disk.  We also account the buffer against
518  * the handle's metadata buffer credits (unless the buffer is already
519  * part of the transaction, that is).
520  *
521  */
522 static int
523 do_get_write_access(handle_t *handle, struct journal_head *jh,
524                         int force_copy)
525 {
526         struct buffer_head *bh;
527         transaction_t *transaction;
528         journal_t *journal;
529         int error;
530         char *frozen_buffer = NULL;
531         int need_copy = 0;
532
533         if (is_handle_aborted(handle))
534                 return -EROFS;
535
536         transaction = handle->h_transaction;
537         journal = transaction->t_journal;
538
539         jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy);
540
541         JBUFFER_TRACE(jh, "entry");
542 repeat:
543         bh = jh2bh(jh);
544
545         /* @@@ Need to check for errors here at some point. */
546
547         lock_buffer(bh);
548         jbd_lock_bh_state(bh);
549
550         /* We now hold the buffer lock so it is safe to query the buffer
551          * state.  Is the buffer dirty?
552          *
553          * If so, there are two possibilities.  The buffer may be
554          * non-journaled, and undergoing a quite legitimate writeback.
555          * Otherwise, it is journaled, and we don't expect dirty buffers
556          * in that state (the buffers should be marked JBD_Dirty
557          * instead.)  So either the IO is being done under our own
558          * control and this is a bug, or it's a third party IO such as
559          * dump(8) (which may leave the buffer scheduled for read ---
560          * ie. locked but not dirty) or tune2fs (which may actually have
561          * the buffer dirtied, ugh.)  */
562
563         if (buffer_dirty(bh)) {
564                 /*
565                  * First question: is this buffer already part of the current
566                  * transaction or the existing committing transaction?
567                  */
568                 if (jh->b_transaction) {
569                         J_ASSERT_JH(jh,
570                                 jh->b_transaction == transaction ||
571                                 jh->b_transaction ==
572                                         journal->j_committing_transaction);
573                         if (jh->b_next_transaction)
574                                 J_ASSERT_JH(jh, jh->b_next_transaction ==
575                                                         transaction);
576                 }
577                 /*
578                  * In any case we need to clean the dirty flag and we must
579                  * do it under the buffer lock to be sure we don't race
580                  * with running write-out.
581                  */
582                 JBUFFER_TRACE(jh, "Unexpected dirty buffer");
583                 jbd_unexpected_dirty_buffer(jh);
584         }
585
586         unlock_buffer(bh);
587
588         error = -EROFS;
589         if (is_handle_aborted(handle)) {
590                 jbd_unlock_bh_state(bh);
591                 goto out;
592         }
593         error = 0;
594
595         /*
596          * The buffer is already part of this transaction if b_transaction or
597          * b_next_transaction points to it
598          */
599         if (jh->b_transaction == transaction ||
600             jh->b_next_transaction == transaction)
601                 goto done;
602
603         /*
604          * If there is already a copy-out version of this buffer, then we don't
605          * need to make another one
606          */
607         if (jh->b_frozen_data) {
608                 JBUFFER_TRACE(jh, "has frozen data");
609                 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
610                 jh->b_next_transaction = transaction;
611                 goto done;
612         }
613
614         /* Is there data here we need to preserve? */
615
616         if (jh->b_transaction && jh->b_transaction != transaction) {
617                 JBUFFER_TRACE(jh, "owned by older transaction");
618                 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
619                 J_ASSERT_JH(jh, jh->b_transaction ==
620                                         journal->j_committing_transaction);
621
622                 /* There is one case we have to be very careful about.
623                  * If the committing transaction is currently writing
624                  * this buffer out to disk and has NOT made a copy-out,
625                  * then we cannot modify the buffer contents at all
626                  * right now.  The essence of copy-out is that it is the
627                  * extra copy, not the primary copy, which gets
628                  * journaled.  If the primary copy is already going to
629                  * disk then we cannot do copy-out here. */
630
631                 if (jh->b_jlist == BJ_Shadow) {
632                         DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
633                         wait_queue_head_t *wqh;
634
635                         wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
636
637                         JBUFFER_TRACE(jh, "on shadow: sleep");
638                         jbd_unlock_bh_state(bh);
639                         /* commit wakes up all shadow buffers after IO */
640                         for ( ; ; ) {
641                                 prepare_to_wait(wqh, &wait.wait,
642                                                 TASK_UNINTERRUPTIBLE);
643                                 if (jh->b_jlist != BJ_Shadow)
644                                         break;
645                                 schedule();
646                         }
647                         finish_wait(wqh, &wait.wait);
648                         goto repeat;
649                 }
650
651                 /* Only do the copy if the currently-owning transaction
652                  * still needs it.  If it is on the Forget list, the
653                  * committing transaction is past that stage.  The
654                  * buffer had better remain locked during the kmalloc,
655                  * but that should be true --- we hold the journal lock
656                  * still and the buffer is already on the BUF_JOURNAL
657                  * list so won't be flushed.
658                  *
659                  * Subtle point, though: if this is a get_undo_access,
660                  * then we will be relying on the frozen_data to contain
661                  * the new value of the committed_data record after the
662                  * transaction, so we HAVE to force the frozen_data copy
663                  * in that case. */
664
665                 if (jh->b_jlist != BJ_Forget || force_copy) {
666                         JBUFFER_TRACE(jh, "generate frozen data");
667                         if (!frozen_buffer) {
668                                 JBUFFER_TRACE(jh, "allocate memory for buffer");
669                                 jbd_unlock_bh_state(bh);
670                                 frozen_buffer =
671                                         jbd2_slab_alloc(jh2bh(jh)->b_size,
672                                                          GFP_NOFS);
673                                 if (!frozen_buffer) {
674                                         printk(KERN_EMERG
675                                                "%s: OOM for frozen_buffer\n",
676                                                __FUNCTION__);
677                                         JBUFFER_TRACE(jh, "oom!");
678                                         error = -ENOMEM;
679                                         jbd_lock_bh_state(bh);
680                                         goto done;
681                                 }
682                                 goto repeat;
683                         }
684                         jh->b_frozen_data = frozen_buffer;
685                         frozen_buffer = NULL;
686                         need_copy = 1;
687                 }
688                 jh->b_next_transaction = transaction;
689         }
690
691
692         /*
693          * Finally, if the buffer is not journaled right now, we need to make
694          * sure it doesn't get written to disk before the caller actually
695          * commits the new data
696          */
697         if (!jh->b_transaction) {
698                 JBUFFER_TRACE(jh, "no transaction");
699                 J_ASSERT_JH(jh, !jh->b_next_transaction);
700                 jh->b_transaction = transaction;
701                 JBUFFER_TRACE(jh, "file as BJ_Reserved");
702                 spin_lock(&journal->j_list_lock);
703                 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
704                 spin_unlock(&journal->j_list_lock);
705         }
706
707 done:
708         if (need_copy) {
709                 struct page *page;
710                 int offset;
711                 char *source;
712
713                 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
714                             "Possible IO failure.\n");
715                 page = jh2bh(jh)->b_page;
716                 offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK;
717                 source = kmap_atomic(page, KM_USER0);
718                 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
719                 kunmap_atomic(source, KM_USER0);
720         }
721         jbd_unlock_bh_state(bh);
722
723         /*
724          * If we are about to journal a buffer, then any revoke pending on it is
725          * no longer valid
726          */
727         jbd2_journal_cancel_revoke(handle, jh);
728
729 out:
730         if (unlikely(frozen_buffer))    /* It's usually NULL */
731                 jbd2_slab_free(frozen_buffer, bh->b_size);
732
733         JBUFFER_TRACE(jh, "exit");
734         return error;
735 }
736
737 /**
738  * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
739  * @handle: transaction to add buffer modifications to
740  * @bh:     bh to be used for metadata writes
741  * @credits: variable that will receive credits for the buffer
742  *
743  * Returns an error code or 0 on success.
744  *
745  * In full data journalling mode the buffer may be of type BJ_AsyncData,
746  * because we're write()ing a buffer which is also part of a shared mapping.
747  */
748
749 int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
750 {
751         struct journal_head *jh = jbd2_journal_add_journal_head(bh);
752         int rc;
753
754         /* We do not want to get caught playing with fields which the
755          * log thread also manipulates.  Make sure that the buffer
756          * completes any outstanding IO before proceeding. */
757         rc = do_get_write_access(handle, jh, 0);
758         jbd2_journal_put_journal_head(jh);
759         return rc;
760 }
761
762
763 /*
764  * When the user wants to journal a newly created buffer_head
765  * (ie. getblk() returned a new buffer and we are going to populate it
766  * manually rather than reading off disk), then we need to keep the
767  * buffer_head locked until it has been completely filled with new
768  * data.  In this case, we should be able to make the assertion that
769  * the bh is not already part of an existing transaction.
770  *
771  * The buffer should already be locked by the caller by this point.
772  * There is no lock ranking violation: it was a newly created,
773  * unlocked buffer beforehand. */
774
775 /**
776  * int jbd2_journal_get_create_access () - notify intent to use newly created bh
777  * @handle: transaction to new buffer to
778  * @bh: new buffer.
779  *
780  * Call this if you create a new bh.
781  */
782 int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
783 {
784         transaction_t *transaction = handle->h_transaction;
785         journal_t *journal = transaction->t_journal;
786         struct journal_head *jh = jbd2_journal_add_journal_head(bh);
787         int err;
788
789         jbd_debug(5, "journal_head %p\n", jh);
790         err = -EROFS;
791         if (is_handle_aborted(handle))
792                 goto out;
793         err = 0;
794
795         JBUFFER_TRACE(jh, "entry");
796         /*
797          * The buffer may already belong to this transaction due to pre-zeroing
798          * in the filesystem's new_block code.  It may also be on the previous,
799          * committing transaction's lists, but it HAS to be in Forget state in
800          * that case: the transaction must have deleted the buffer for it to be
801          * reused here.
802          */
803         jbd_lock_bh_state(bh);
804         spin_lock(&journal->j_list_lock);
805         J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
806                 jh->b_transaction == NULL ||
807                 (jh->b_transaction == journal->j_committing_transaction &&
808                           jh->b_jlist == BJ_Forget)));
809
810         J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
811         J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
812
813         if (jh->b_transaction == NULL) {
814                 jh->b_transaction = transaction;
815                 JBUFFER_TRACE(jh, "file as BJ_Reserved");
816                 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
817         } else if (jh->b_transaction == journal->j_committing_transaction) {
818                 JBUFFER_TRACE(jh, "set next transaction");
819                 jh->b_next_transaction = transaction;
820         }
821         spin_unlock(&journal->j_list_lock);
822         jbd_unlock_bh_state(bh);
823
824         /*
825          * akpm: I added this.  ext3_alloc_branch can pick up new indirect
826          * blocks which contain freed but then revoked metadata.  We need
827          * to cancel the revoke in case we end up freeing it yet again
828          * and the reallocating as data - this would cause a second revoke,
829          * which hits an assertion error.
830          */
831         JBUFFER_TRACE(jh, "cancelling revoke");
832         jbd2_journal_cancel_revoke(handle, jh);
833         jbd2_journal_put_journal_head(jh);
834 out:
835         return err;
836 }
837
838 /**
839  * int jbd2_journal_get_undo_access() -  Notify intent to modify metadata with
840  *     non-rewindable consequences
841  * @handle: transaction
842  * @bh: buffer to undo
843  * @credits: store the number of taken credits here (if not NULL)
844  *
845  * Sometimes there is a need to distinguish between metadata which has
846  * been committed to disk and that which has not.  The ext3fs code uses
847  * this for freeing and allocating space, we have to make sure that we
848  * do not reuse freed space until the deallocation has been committed,
849  * since if we overwrote that space we would make the delete
850  * un-rewindable in case of a crash.
851  *
852  * To deal with that, jbd2_journal_get_undo_access requests write access to a
853  * buffer for parts of non-rewindable operations such as delete
854  * operations on the bitmaps.  The journaling code must keep a copy of
855  * the buffer's contents prior to the undo_access call until such time
856  * as we know that the buffer has definitely been committed to disk.
857  *
858  * We never need to know which transaction the committed data is part
859  * of, buffers touched here are guaranteed to be dirtied later and so
860  * will be committed to a new transaction in due course, at which point
861  * we can discard the old committed data pointer.
862  *
863  * Returns error number or 0 on success.
864  */
865 int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
866 {
867         int err;
868         struct journal_head *jh = jbd2_journal_add_journal_head(bh);
869         char *committed_data = NULL;
870
871         JBUFFER_TRACE(jh, "entry");
872
873         /*
874          * Do this first --- it can drop the journal lock, so we want to
875          * make sure that obtaining the committed_data is done
876          * atomically wrt. completion of any outstanding commits.
877          */
878         err = do_get_write_access(handle, jh, 1);
879         if (err)
880                 goto out;
881
882 repeat:
883         if (!jh->b_committed_data) {
884                 committed_data = jbd2_slab_alloc(jh2bh(jh)->b_size, GFP_NOFS);
885                 if (!committed_data) {
886                         printk(KERN_EMERG "%s: No memory for committed data\n",
887                                 __FUNCTION__);
888                         err = -ENOMEM;
889                         goto out;
890                 }
891         }
892
893         jbd_lock_bh_state(bh);
894         if (!jh->b_committed_data) {
895                 /* Copy out the current buffer contents into the
896                  * preserved, committed copy. */
897                 JBUFFER_TRACE(jh, "generate b_committed data");
898                 if (!committed_data) {
899                         jbd_unlock_bh_state(bh);
900                         goto repeat;
901                 }
902
903                 jh->b_committed_data = committed_data;
904                 committed_data = NULL;
905                 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
906         }
907         jbd_unlock_bh_state(bh);
908 out:
909         jbd2_journal_put_journal_head(jh);
910         if (unlikely(committed_data))
911                 jbd2_slab_free(committed_data, bh->b_size);
912         return err;
913 }
914
915 /**
916  * int jbd2_journal_dirty_data() -  mark a buffer as containing dirty data which
917  *                             needs to be flushed before we can commit the
918  *                             current transaction.
919  * @handle: transaction
920  * @bh: bufferhead to mark
921  *
922  * The buffer is placed on the transaction's data list and is marked as
923  * belonging to the transaction.
924  *
925  * Returns error number or 0 on success.
926  *
927  * jbd2_journal_dirty_data() can be called via page_launder->ext3_writepage
928  * by kswapd.
929  */
930 int jbd2_journal_dirty_data(handle_t *handle, struct buffer_head *bh)
931 {
932         journal_t *journal = handle->h_transaction->t_journal;
933         int need_brelse = 0;
934         struct journal_head *jh;
935
936         if (is_handle_aborted(handle))
937                 return 0;
938
939         jh = jbd2_journal_add_journal_head(bh);
940         JBUFFER_TRACE(jh, "entry");
941
942         /*
943          * The buffer could *already* be dirty.  Writeout can start
944          * at any time.
945          */
946         jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
947
948         /*
949          * What if the buffer is already part of a running transaction?
950          *
951          * There are two cases:
952          * 1) It is part of the current running transaction.  Refile it,
953          *    just in case we have allocated it as metadata, deallocated
954          *    it, then reallocated it as data.
955          * 2) It is part of the previous, still-committing transaction.
956          *    If all we want to do is to guarantee that the buffer will be
957          *    written to disk before this new transaction commits, then
958          *    being sure that the *previous* transaction has this same
959          *    property is sufficient for us!  Just leave it on its old
960          *    transaction.
961          *
962          * In case (2), the buffer must not already exist as metadata
963          * --- that would violate write ordering (a transaction is free
964          * to write its data at any point, even before the previous
965          * committing transaction has committed).  The caller must
966          * never, ever allow this to happen: there's nothing we can do
967          * about it in this layer.
968          */
969         jbd_lock_bh_state(bh);
970         spin_lock(&journal->j_list_lock);
971
972         /* Now that we have bh_state locked, are we really still mapped? */
973         if (!buffer_mapped(bh)) {
974                 JBUFFER_TRACE(jh, "unmapped buffer, bailing out");
975                 goto no_journal;
976         }
977
978         if (jh->b_transaction) {
979                 JBUFFER_TRACE(jh, "has transaction");
980                 if (jh->b_transaction != handle->h_transaction) {
981                         JBUFFER_TRACE(jh, "belongs to older transaction");
982                         J_ASSERT_JH(jh, jh->b_transaction ==
983                                         journal->j_committing_transaction);
984
985                         /* @@@ IS THIS TRUE  ? */
986                         /*
987                          * Not any more.  Scenario: someone does a write()
988                          * in data=journal mode.  The buffer's transaction has
989                          * moved into commit.  Then someone does another
990                          * write() to the file.  We do the frozen data copyout
991                          * and set b_next_transaction to point to j_running_t.
992                          * And while we're in that state, someone does a
993                          * writepage() in an attempt to pageout the same area
994                          * of the file via a shared mapping.  At present that
995                          * calls jbd2_journal_dirty_data(), and we get right here.
996                          * It may be too late to journal the data.  Simply
997                          * falling through to the next test will suffice: the
998                          * data will be dirty and wil be checkpointed.  The
999                          * ordering comments in the next comment block still
1000                          * apply.
1001                          */
1002                         //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1003
1004                         /*
1005                          * If we're journalling data, and this buffer was
1006                          * subject to a write(), it could be metadata, forget
1007                          * or shadow against the committing transaction.  Now,
1008                          * someone has dirtied the same darn page via a mapping
1009                          * and it is being writepage()'d.
1010                          * We *could* just steal the page from commit, with some
1011                          * fancy locking there.  Instead, we just skip it -
1012                          * don't tie the page's buffers to the new transaction
1013                          * at all.
1014                          * Implication: if we crash before the writepage() data
1015                          * is written into the filesystem, recovery will replay
1016                          * the write() data.
1017                          */
1018                         if (jh->b_jlist != BJ_None &&
1019                                         jh->b_jlist != BJ_SyncData &&
1020                                         jh->b_jlist != BJ_Locked) {
1021                                 JBUFFER_TRACE(jh, "Not stealing");
1022                                 goto no_journal;
1023                         }
1024
1025                         /*
1026                          * This buffer may be undergoing writeout in commit.  We
1027                          * can't return from here and let the caller dirty it
1028                          * again because that can cause the write-out loop in
1029                          * commit to never terminate.
1030                          */
1031                         if (buffer_dirty(bh)) {
1032                                 get_bh(bh);
1033                                 spin_unlock(&journal->j_list_lock);
1034                                 jbd_unlock_bh_state(bh);
1035                                 need_brelse = 1;
1036                                 sync_dirty_buffer(bh);
1037                                 jbd_lock_bh_state(bh);
1038                                 spin_lock(&journal->j_list_lock);
1039                                 /* Since we dropped the lock... */
1040                                 if (!buffer_mapped(bh)) {
1041                                         JBUFFER_TRACE(jh, "buffer got unmapped");
1042                                         goto no_journal;
1043                                 }
1044                                 /* The buffer may become locked again at any
1045                                    time if it is redirtied */
1046                         }
1047
1048                         /* journal_clean_data_list() may have got there first */
1049                         if (jh->b_transaction != NULL) {
1050                                 JBUFFER_TRACE(jh, "unfile from commit");
1051                                 __jbd2_journal_temp_unlink_buffer(jh);
1052                                 /* It still points to the committing
1053                                  * transaction; move it to this one so
1054                                  * that the refile assert checks are
1055                                  * happy. */
1056                                 jh->b_transaction = handle->h_transaction;
1057                         }
1058                         /* The buffer will be refiled below */
1059
1060                 }
1061                 /*
1062                  * Special case --- the buffer might actually have been
1063                  * allocated and then immediately deallocated in the previous,
1064                  * committing transaction, so might still be left on that
1065                  * transaction's metadata lists.
1066                  */
1067                 if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
1068                         JBUFFER_TRACE(jh, "not on correct data list: unfile");
1069                         J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
1070                         __jbd2_journal_temp_unlink_buffer(jh);
1071                         jh->b_transaction = handle->h_transaction;
1072                         JBUFFER_TRACE(jh, "file as data");
1073                         __jbd2_journal_file_buffer(jh, handle->h_transaction,
1074                                                 BJ_SyncData);
1075                 }
1076         } else {
1077                 JBUFFER_TRACE(jh, "not on a transaction");
1078                 __jbd2_journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
1079         }
1080 no_journal:
1081         spin_unlock(&journal->j_list_lock);
1082         jbd_unlock_bh_state(bh);
1083         if (need_brelse) {
1084                 BUFFER_TRACE(bh, "brelse");
1085                 __brelse(bh);
1086         }
1087         JBUFFER_TRACE(jh, "exit");
1088         jbd2_journal_put_journal_head(jh);
1089         return 0;
1090 }
1091
1092 /**
1093  * int jbd2_journal_dirty_metadata() -  mark a buffer as containing dirty metadata
1094  * @handle: transaction to add buffer to.
1095  * @bh: buffer to mark
1096  *
1097  * mark dirty metadata which needs to be journaled as part of the current
1098  * transaction.
1099  *
1100  * The buffer is placed on the transaction's metadata list and is marked
1101  * as belonging to the transaction.
1102  *
1103  * Returns error number or 0 on success.
1104  *
1105  * Special care needs to be taken if the buffer already belongs to the
1106  * current committing transaction (in which case we should have frozen
1107  * data present for that commit).  In that case, we don't relink the
1108  * buffer: that only gets done when the old transaction finally
1109  * completes its commit.
1110  */
1111 int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1112 {
1113         transaction_t *transaction = handle->h_transaction;
1114         journal_t *journal = transaction->t_journal;
1115         struct journal_head *jh = bh2jh(bh);
1116
1117         jbd_debug(5, "journal_head %p\n", jh);
1118         JBUFFER_TRACE(jh, "entry");
1119         if (is_handle_aborted(handle))
1120                 goto out;
1121
1122         jbd_lock_bh_state(bh);
1123
1124         if (jh->b_modified == 0) {
1125                 /*
1126                  * This buffer's got modified and becoming part
1127                  * of the transaction. This needs to be done
1128                  * once a transaction -bzzz
1129                  */
1130                 jh->b_modified = 1;
1131                 J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
1132                 handle->h_buffer_credits--;
1133         }
1134
1135         /*
1136          * fastpath, to avoid expensive locking.  If this buffer is already
1137          * on the running transaction's metadata list there is nothing to do.
1138          * Nobody can take it off again because there is a handle open.
1139          * I _think_ we're OK here with SMP barriers - a mistaken decision will
1140          * result in this test being false, so we go in and take the locks.
1141          */
1142         if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1143                 JBUFFER_TRACE(jh, "fastpath");
1144                 J_ASSERT_JH(jh, jh->b_transaction ==
1145                                         journal->j_running_transaction);
1146                 goto out_unlock_bh;
1147         }
1148
1149         set_buffer_jbddirty(bh);
1150
1151         /*
1152          * Metadata already on the current transaction list doesn't
1153          * need to be filed.  Metadata on another transaction's list must
1154          * be committing, and will be refiled once the commit completes:
1155          * leave it alone for now.
1156          */
1157         if (jh->b_transaction != transaction) {
1158                 JBUFFER_TRACE(jh, "already on other transaction");
1159                 J_ASSERT_JH(jh, jh->b_transaction ==
1160                                         journal->j_committing_transaction);
1161                 J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
1162                 /* And this case is illegal: we can't reuse another
1163                  * transaction's data buffer, ever. */
1164                 goto out_unlock_bh;
1165         }
1166
1167         /* That test should have eliminated the following case: */
1168         J_ASSERT_JH(jh, jh->b_frozen_data == 0);
1169
1170         JBUFFER_TRACE(jh, "file as BJ_Metadata");
1171         spin_lock(&journal->j_list_lock);
1172         __jbd2_journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1173         spin_unlock(&journal->j_list_lock);
1174 out_unlock_bh:
1175         jbd_unlock_bh_state(bh);
1176 out:
1177         JBUFFER_TRACE(jh, "exit");
1178         return 0;
1179 }
1180
1181 /*
1182  * jbd2_journal_release_buffer: undo a get_write_access without any buffer
1183  * updates, if the update decided in the end that it didn't need access.
1184  *
1185  */
1186 void
1187 jbd2_journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1188 {
1189         BUFFER_TRACE(bh, "entry");
1190 }
1191
1192 /**
1193  * void jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1194  * @handle: transaction handle
1195  * @bh:     bh to 'forget'
1196  *
1197  * We can only do the bforget if there are no commits pending against the
1198  * buffer.  If the buffer is dirty in the current running transaction we
1199  * can safely unlink it.
1200  *
1201  * bh may not be a journalled buffer at all - it may be a non-JBD
1202  * buffer which came off the hashtable.  Check for this.
1203  *
1204  * Decrements bh->b_count by one.
1205  *
1206  * Allow this call even if the handle has aborted --- it may be part of
1207  * the caller's cleanup after an abort.
1208  */
1209 int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh)
1210 {
1211         transaction_t *transaction = handle->h_transaction;
1212         journal_t *journal = transaction->t_journal;
1213         struct journal_head *jh;
1214         int drop_reserve = 0;
1215         int err = 0;
1216
1217         BUFFER_TRACE(bh, "entry");
1218
1219         jbd_lock_bh_state(bh);
1220         spin_lock(&journal->j_list_lock);
1221
1222         if (!buffer_jbd(bh))
1223                 goto not_jbd;
1224         jh = bh2jh(bh);
1225
1226         /* Critical error: attempting to delete a bitmap buffer, maybe?
1227          * Don't do any jbd operations, and return an error. */
1228         if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1229                          "inconsistent data on disk")) {
1230                 err = -EIO;
1231                 goto not_jbd;
1232         }
1233
1234         /*
1235          * The buffer's going from the transaction, we must drop
1236          * all references -bzzz
1237          */
1238         jh->b_modified = 0;
1239
1240         if (jh->b_transaction == handle->h_transaction) {
1241                 J_ASSERT_JH(jh, !jh->b_frozen_data);
1242
1243                 /* If we are forgetting a buffer which is already part
1244                  * of this transaction, then we can just drop it from
1245                  * the transaction immediately. */
1246                 clear_buffer_dirty(bh);
1247                 clear_buffer_jbddirty(bh);
1248
1249                 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1250
1251                 drop_reserve = 1;
1252
1253                 /*
1254                  * We are no longer going to journal this buffer.
1255                  * However, the commit of this transaction is still
1256                  * important to the buffer: the delete that we are now
1257                  * processing might obsolete an old log entry, so by
1258                  * committing, we can satisfy the buffer's checkpoint.
1259                  *
1260                  * So, if we have a checkpoint on the buffer, we should
1261                  * now refile the buffer on our BJ_Forget list so that
1262                  * we know to remove the checkpoint after we commit.
1263                  */
1264
1265                 if (jh->b_cp_transaction) {
1266                         __jbd2_journal_temp_unlink_buffer(jh);
1267                         __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1268                 } else {
1269                         __jbd2_journal_unfile_buffer(jh);
1270                         jbd2_journal_remove_journal_head(bh);
1271                         __brelse(bh);
1272                         if (!buffer_jbd(bh)) {
1273                                 spin_unlock(&journal->j_list_lock);
1274                                 jbd_unlock_bh_state(bh);
1275                                 __bforget(bh);
1276                                 goto drop;
1277                         }
1278                 }
1279         } else if (jh->b_transaction) {
1280                 J_ASSERT_JH(jh, (jh->b_transaction ==
1281                                  journal->j_committing_transaction));
1282                 /* However, if the buffer is still owned by a prior
1283                  * (committing) transaction, we can't drop it yet... */
1284                 JBUFFER_TRACE(jh, "belongs to older transaction");
1285                 /* ... but we CAN drop it from the new transaction if we
1286                  * have also modified it since the original commit. */
1287
1288                 if (jh->b_next_transaction) {
1289                         J_ASSERT(jh->b_next_transaction == transaction);
1290                         jh->b_next_transaction = NULL;
1291                         drop_reserve = 1;
1292                 }
1293         }
1294
1295 not_jbd:
1296         spin_unlock(&journal->j_list_lock);
1297         jbd_unlock_bh_state(bh);
1298         __brelse(bh);
1299 drop:
1300         if (drop_reserve) {
1301                 /* no need to reserve log space for this block -bzzz */
1302                 handle->h_buffer_credits++;
1303         }
1304         return err;
1305 }
1306
1307 /**
1308  * int jbd2_journal_stop() - complete a transaction
1309  * @handle: tranaction to complete.
1310  *
1311  * All done for a particular handle.
1312  *
1313  * There is not much action needed here.  We just return any remaining
1314  * buffer credits to the transaction and remove the handle.  The only
1315  * complication is that we need to start a commit operation if the
1316  * filesystem is marked for synchronous update.
1317  *
1318  * jbd2_journal_stop itself will not usually return an error, but it may
1319  * do so in unusual circumstances.  In particular, expect it to
1320  * return -EIO if a jbd2_journal_abort has been executed since the
1321  * transaction began.
1322  */
1323 int jbd2_journal_stop(handle_t *handle)
1324 {
1325         transaction_t *transaction = handle->h_transaction;
1326         journal_t *journal = transaction->t_journal;
1327         int old_handle_count, err;
1328         pid_t pid;
1329
1330         J_ASSERT(journal_current_handle() == handle);
1331
1332         if (is_handle_aborted(handle))
1333                 err = -EIO;
1334         else {
1335                 J_ASSERT(transaction->t_updates > 0);
1336                 err = 0;
1337         }
1338
1339         if (--handle->h_ref > 0) {
1340                 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1341                           handle->h_ref);
1342                 return err;
1343         }
1344
1345         jbd_debug(4, "Handle %p going down\n", handle);
1346
1347         /*
1348          * Implement synchronous transaction batching.  If the handle
1349          * was synchronous, don't force a commit immediately.  Let's
1350          * yield and let another thread piggyback onto this transaction.
1351          * Keep doing that while new threads continue to arrive.
1352          * It doesn't cost much - we're about to run a commit and sleep
1353          * on IO anyway.  Speeds up many-threaded, many-dir operations
1354          * by 30x or more...
1355          *
1356          * But don't do this if this process was the most recent one to
1357          * perform a synchronous write.  We do this to detect the case where a
1358          * single process is doing a stream of sync writes.  No point in waiting
1359          * for joiners in that case.
1360          */
1361         pid = current->pid;
1362         if (handle->h_sync && journal->j_last_sync_writer != pid) {
1363                 journal->j_last_sync_writer = pid;
1364                 do {
1365                         old_handle_count = transaction->t_handle_count;
1366                         schedule_timeout_uninterruptible(1);
1367                 } while (old_handle_count != transaction->t_handle_count);
1368         }
1369
1370         current->journal_info = NULL;
1371         spin_lock(&journal->j_state_lock);
1372         spin_lock(&transaction->t_handle_lock);
1373         transaction->t_outstanding_credits -= handle->h_buffer_credits;
1374         transaction->t_updates--;
1375         if (!transaction->t_updates) {
1376                 wake_up(&journal->j_wait_updates);
1377                 if (journal->j_barrier_count)
1378                         wake_up(&journal->j_wait_transaction_locked);
1379         }
1380
1381         /*
1382          * If the handle is marked SYNC, we need to set another commit
1383          * going!  We also want to force a commit if the current
1384          * transaction is occupying too much of the log, or if the
1385          * transaction is too old now.
1386          */
1387         if (handle->h_sync ||
1388                         transaction->t_outstanding_credits >
1389                                 journal->j_max_transaction_buffers ||
1390                         time_after_eq(jiffies, transaction->t_expires)) {
1391                 /* Do this even for aborted journals: an abort still
1392                  * completes the commit thread, it just doesn't write
1393                  * anything to disk. */
1394                 tid_t tid = transaction->t_tid;
1395
1396                 spin_unlock(&transaction->t_handle_lock);
1397                 jbd_debug(2, "transaction too old, requesting commit for "
1398                                         "handle %p\n", handle);
1399                 /* This is non-blocking */
1400                 __jbd2_log_start_commit(journal, transaction->t_tid);
1401                 spin_unlock(&journal->j_state_lock);
1402
1403                 /*
1404                  * Special case: JBD2_SYNC synchronous updates require us
1405                  * to wait for the commit to complete.
1406                  */
1407                 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1408                         err = jbd2_log_wait_commit(journal, tid);
1409         } else {
1410                 spin_unlock(&transaction->t_handle_lock);
1411                 spin_unlock(&journal->j_state_lock);
1412         }
1413
1414         jbd_free_handle(handle);
1415         return err;
1416 }
1417
1418 /**int jbd2_journal_force_commit() - force any uncommitted transactions
1419  * @journal: journal to force
1420  *
1421  * For synchronous operations: force any uncommitted transactions
1422  * to disk.  May seem kludgy, but it reuses all the handle batching
1423  * code in a very simple manner.
1424  */
1425 int jbd2_journal_force_commit(journal_t *journal)
1426 {
1427         handle_t *handle;
1428         int ret;
1429
1430         handle = jbd2_journal_start(journal, 1);
1431         if (IS_ERR(handle)) {
1432                 ret = PTR_ERR(handle);
1433         } else {
1434                 handle->h_sync = 1;
1435                 ret = jbd2_journal_stop(handle);
1436         }
1437         return ret;
1438 }
1439
1440 /*
1441  *
1442  * List management code snippets: various functions for manipulating the
1443  * transaction buffer lists.
1444  *
1445  */
1446
1447 /*
1448  * Append a buffer to a transaction list, given the transaction's list head
1449  * pointer.
1450  *
1451  * j_list_lock is held.
1452  *
1453  * jbd_lock_bh_state(jh2bh(jh)) is held.
1454  */
1455
1456 static inline void
1457 __blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1458 {
1459         if (!*list) {
1460                 jh->b_tnext = jh->b_tprev = jh;
1461                 *list = jh;
1462         } else {
1463                 /* Insert at the tail of the list to preserve order */
1464                 struct journal_head *first = *list, *last = first->b_tprev;
1465                 jh->b_tprev = last;
1466                 jh->b_tnext = first;
1467                 last->b_tnext = first->b_tprev = jh;
1468         }
1469 }
1470
1471 /*
1472  * Remove a buffer from a transaction list, given the transaction's list
1473  * head pointer.
1474  *
1475  * Called with j_list_lock held, and the journal may not be locked.
1476  *
1477  * jbd_lock_bh_state(jh2bh(jh)) is held.
1478  */
1479
1480 static inline void
1481 __blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1482 {
1483         if (*list == jh) {
1484                 *list = jh->b_tnext;
1485                 if (*list == jh)
1486                         *list = NULL;
1487         }
1488         jh->b_tprev->b_tnext = jh->b_tnext;
1489         jh->b_tnext->b_tprev = jh->b_tprev;
1490 }
1491
1492 /*
1493  * Remove a buffer from the appropriate transaction list.
1494  *
1495  * Note that this function can *change* the value of
1496  * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
1497  * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list.  If the caller
1498  * is holding onto a copy of one of thee pointers, it could go bad.
1499  * Generally the caller needs to re-read the pointer from the transaction_t.
1500  *
1501  * Called under j_list_lock.  The journal may not be locked.
1502  */
1503 void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
1504 {
1505         struct journal_head **list = NULL;
1506         transaction_t *transaction;
1507         struct buffer_head *bh = jh2bh(jh);
1508
1509         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1510         transaction = jh->b_transaction;
1511         if (transaction)
1512                 assert_spin_locked(&transaction->t_journal->j_list_lock);
1513
1514         J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1515         if (jh->b_jlist != BJ_None)
1516                 J_ASSERT_JH(jh, transaction != 0);
1517
1518         switch (jh->b_jlist) {
1519         case BJ_None:
1520                 return;
1521         case BJ_SyncData:
1522                 list = &transaction->t_sync_datalist;
1523                 break;
1524         case BJ_Metadata:
1525                 transaction->t_nr_buffers--;
1526                 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1527                 list = &transaction->t_buffers;
1528                 break;
1529         case BJ_Forget:
1530                 list = &transaction->t_forget;
1531                 break;
1532         case BJ_IO:
1533                 list = &transaction->t_iobuf_list;
1534                 break;
1535         case BJ_Shadow:
1536                 list = &transaction->t_shadow_list;
1537                 break;
1538         case BJ_LogCtl:
1539                 list = &transaction->t_log_list;
1540                 break;
1541         case BJ_Reserved:
1542                 list = &transaction->t_reserved_list;
1543                 break;
1544         case BJ_Locked:
1545                 list = &transaction->t_locked_list;
1546                 break;
1547         }
1548
1549         __blist_del_buffer(list, jh);
1550         jh->b_jlist = BJ_None;
1551         if (test_clear_buffer_jbddirty(bh))
1552                 mark_buffer_dirty(bh);  /* Expose it to the VM */
1553 }
1554
1555 void __jbd2_journal_unfile_buffer(struct journal_head *jh)
1556 {
1557         __jbd2_journal_temp_unlink_buffer(jh);
1558         jh->b_transaction = NULL;
1559 }
1560
1561 void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1562 {
1563         jbd_lock_bh_state(jh2bh(jh));
1564         spin_lock(&journal->j_list_lock);
1565         __jbd2_journal_unfile_buffer(jh);
1566         spin_unlock(&journal->j_list_lock);
1567         jbd_unlock_bh_state(jh2bh(jh));
1568 }
1569
1570 /*
1571  * Called from jbd2_journal_try_to_free_buffers().
1572  *
1573  * Called under jbd_lock_bh_state(bh)
1574  */
1575 static void
1576 __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1577 {
1578         struct journal_head *jh;
1579
1580         jh = bh2jh(bh);
1581
1582         if (buffer_locked(bh) || buffer_dirty(bh))
1583                 goto out;
1584
1585         if (jh->b_next_transaction != 0)
1586                 goto out;
1587
1588         spin_lock(&journal->j_list_lock);
1589         if (jh->b_transaction != 0 && jh->b_cp_transaction == 0) {
1590                 if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
1591                         /* A written-back ordered data buffer */
1592                         JBUFFER_TRACE(jh, "release data");
1593                         __jbd2_journal_unfile_buffer(jh);
1594                         jbd2_journal_remove_journal_head(bh);
1595                         __brelse(bh);
1596                 }
1597         } else if (jh->b_cp_transaction != 0 && jh->b_transaction == 0) {
1598                 /* written-back checkpointed metadata buffer */
1599                 if (jh->b_jlist == BJ_None) {
1600                         JBUFFER_TRACE(jh, "remove from checkpoint list");
1601                         __jbd2_journal_remove_checkpoint(jh);
1602                         jbd2_journal_remove_journal_head(bh);
1603                         __brelse(bh);
1604                 }
1605         }
1606         spin_unlock(&journal->j_list_lock);
1607 out:
1608         return;
1609 }
1610
1611
1612 /**
1613  * int jbd2_journal_try_to_free_buffers() - try to free page buffers.
1614  * @journal: journal for operation
1615  * @page: to try and free
1616  * @unused_gfp_mask: unused
1617  *
1618  *
1619  * For all the buffers on this page,
1620  * if they are fully written out ordered data, move them onto BUF_CLEAN
1621  * so try_to_free_buffers() can reap them.
1622  *
1623  * This function returns non-zero if we wish try_to_free_buffers()
1624  * to be called. We do this if the page is releasable by try_to_free_buffers().
1625  * We also do it if the page has locked or dirty buffers and the caller wants
1626  * us to perform sync or async writeout.
1627  *
1628  * This complicates JBD locking somewhat.  We aren't protected by the
1629  * BKL here.  We wish to remove the buffer from its committing or
1630  * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
1631  *
1632  * This may *change* the value of transaction_t->t_datalist, so anyone
1633  * who looks at t_datalist needs to lock against this function.
1634  *
1635  * Even worse, someone may be doing a jbd2_journal_dirty_data on this
1636  * buffer.  So we need to lock against that.  jbd2_journal_dirty_data()
1637  * will come out of the lock with the buffer dirty, which makes it
1638  * ineligible for release here.
1639  *
1640  * Who else is affected by this?  hmm...  Really the only contender
1641  * is do_get_write_access() - it could be looking at the buffer while
1642  * journal_try_to_free_buffer() is changing its state.  But that
1643  * cannot happen because we never reallocate freed data as metadata
1644  * while the data is part of a transaction.  Yes?
1645  */
1646 int jbd2_journal_try_to_free_buffers(journal_t *journal,
1647                                 struct page *page, gfp_t unused_gfp_mask)
1648 {
1649         struct buffer_head *head;
1650         struct buffer_head *bh;
1651         int ret = 0;
1652
1653         J_ASSERT(PageLocked(page));
1654
1655         head = page_buffers(page);
1656         bh = head;
1657         do {
1658                 struct journal_head *jh;
1659
1660                 /*
1661                  * We take our own ref against the journal_head here to avoid
1662                  * having to add tons of locking around each instance of
1663                  * jbd2_journal_remove_journal_head() and jbd2_journal_put_journal_head().
1664                  */
1665                 jh = jbd2_journal_grab_journal_head(bh);
1666                 if (!jh)
1667                         continue;
1668
1669                 jbd_lock_bh_state(bh);
1670                 __journal_try_to_free_buffer(journal, bh);
1671                 jbd2_journal_put_journal_head(jh);
1672                 jbd_unlock_bh_state(bh);
1673                 if (buffer_jbd(bh))
1674                         goto busy;
1675         } while ((bh = bh->b_this_page) != head);
1676         ret = try_to_free_buffers(page);
1677 busy:
1678         return ret;
1679 }
1680
1681 /*
1682  * This buffer is no longer needed.  If it is on an older transaction's
1683  * checkpoint list we need to record it on this transaction's forget list
1684  * to pin this buffer (and hence its checkpointing transaction) down until
1685  * this transaction commits.  If the buffer isn't on a checkpoint list, we
1686  * release it.
1687  * Returns non-zero if JBD no longer has an interest in the buffer.
1688  *
1689  * Called under j_list_lock.
1690  *
1691  * Called under jbd_lock_bh_state(bh).
1692  */
1693 static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1694 {
1695         int may_free = 1;
1696         struct buffer_head *bh = jh2bh(jh);
1697
1698         __jbd2_journal_unfile_buffer(jh);
1699
1700         if (jh->b_cp_transaction) {
1701                 JBUFFER_TRACE(jh, "on running+cp transaction");
1702                 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1703                 clear_buffer_jbddirty(bh);
1704                 may_free = 0;
1705         } else {
1706                 JBUFFER_TRACE(jh, "on running transaction");
1707                 jbd2_journal_remove_journal_head(bh);
1708                 __brelse(bh);
1709         }
1710         return may_free;
1711 }
1712
1713 /*
1714  * jbd2_journal_invalidatepage
1715  *
1716  * This code is tricky.  It has a number of cases to deal with.
1717  *
1718  * There are two invariants which this code relies on:
1719  *
1720  * i_size must be updated on disk before we start calling invalidatepage on the
1721  * data.
1722  *
1723  *  This is done in ext3 by defining an ext3_setattr method which
1724  *  updates i_size before truncate gets going.  By maintaining this
1725  *  invariant, we can be sure that it is safe to throw away any buffers
1726  *  attached to the current transaction: once the transaction commits,
1727  *  we know that the data will not be needed.
1728  *
1729  *  Note however that we can *not* throw away data belonging to the
1730  *  previous, committing transaction!
1731  *
1732  * Any disk blocks which *are* part of the previous, committing
1733  * transaction (and which therefore cannot be discarded immediately) are
1734  * not going to be reused in the new running transaction
1735  *
1736  *  The bitmap committed_data images guarantee this: any block which is
1737  *  allocated in one transaction and removed in the next will be marked
1738  *  as in-use in the committed_data bitmap, so cannot be reused until
1739  *  the next transaction to delete the block commits.  This means that
1740  *  leaving committing buffers dirty is quite safe: the disk blocks
1741  *  cannot be reallocated to a different file and so buffer aliasing is
1742  *  not possible.
1743  *
1744  *
1745  * The above applies mainly to ordered data mode.  In writeback mode we
1746  * don't make guarantees about the order in which data hits disk --- in
1747  * particular we don't guarantee that new dirty data is flushed before
1748  * transaction commit --- so it is always safe just to discard data
1749  * immediately in that mode.  --sct
1750  */
1751
1752 /*
1753  * The journal_unmap_buffer helper function returns zero if the buffer
1754  * concerned remains pinned as an anonymous buffer belonging to an older
1755  * transaction.
1756  *
1757  * We're outside-transaction here.  Either or both of j_running_transaction
1758  * and j_committing_transaction may be NULL.
1759  */
1760 static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1761 {
1762         transaction_t *transaction;
1763         struct journal_head *jh;
1764         int may_free = 1;
1765         int ret;
1766
1767         BUFFER_TRACE(bh, "entry");
1768
1769         /*
1770          * It is safe to proceed here without the j_list_lock because the
1771          * buffers cannot be stolen by try_to_free_buffers as long as we are
1772          * holding the page lock. --sct
1773          */
1774
1775         if (!buffer_jbd(bh))
1776                 goto zap_buffer_unlocked;
1777
1778         spin_lock(&journal->j_state_lock);
1779         jbd_lock_bh_state(bh);
1780         spin_lock(&journal->j_list_lock);
1781
1782         jh = jbd2_journal_grab_journal_head(bh);
1783         if (!jh)
1784                 goto zap_buffer_no_jh;
1785
1786         transaction = jh->b_transaction;
1787         if (transaction == NULL) {
1788                 /* First case: not on any transaction.  If it
1789                  * has no checkpoint link, then we can zap it:
1790                  * it's a writeback-mode buffer so we don't care
1791                  * if it hits disk safely. */
1792                 if (!jh->b_cp_transaction) {
1793                         JBUFFER_TRACE(jh, "not on any transaction: zap");
1794                         goto zap_buffer;
1795                 }
1796
1797                 if (!buffer_dirty(bh)) {
1798                         /* bdflush has written it.  We can drop it now */
1799                         goto zap_buffer;
1800                 }
1801
1802                 /* OK, it must be in the journal but still not
1803                  * written fully to disk: it's metadata or
1804                  * journaled data... */
1805
1806                 if (journal->j_running_transaction) {
1807                         /* ... and once the current transaction has
1808                          * committed, the buffer won't be needed any
1809                          * longer. */
1810                         JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1811                         ret = __dispose_buffer(jh,
1812                                         journal->j_running_transaction);
1813                         jbd2_journal_put_journal_head(jh);
1814                         spin_unlock(&journal->j_list_lock);
1815                         jbd_unlock_bh_state(bh);
1816                         spin_unlock(&journal->j_state_lock);
1817                         return ret;
1818                 } else {
1819                         /* There is no currently-running transaction. So the
1820                          * orphan record which we wrote for this file must have
1821                          * passed into commit.  We must attach this buffer to
1822                          * the committing transaction, if it exists. */
1823                         if (journal->j_committing_transaction) {
1824                                 JBUFFER_TRACE(jh, "give to committing trans");
1825                                 ret = __dispose_buffer(jh,
1826                                         journal->j_committing_transaction);
1827                                 jbd2_journal_put_journal_head(jh);
1828                                 spin_unlock(&journal->j_list_lock);
1829                                 jbd_unlock_bh_state(bh);
1830                                 spin_unlock(&journal->j_state_lock);
1831                                 return ret;
1832                         } else {
1833                                 /* The orphan record's transaction has
1834                                  * committed.  We can cleanse this buffer */
1835                                 clear_buffer_jbddirty(bh);
1836                                 goto zap_buffer;
1837                         }
1838                 }
1839         } else if (transaction == journal->j_committing_transaction) {
1840                 JBUFFER_TRACE(jh, "on committing transaction");
1841                 if (jh->b_jlist == BJ_Locked) {
1842                         /*
1843                          * The buffer is on the committing transaction's locked
1844                          * list.  We have the buffer locked, so I/O has
1845                          * completed.  So we can nail the buffer now.
1846                          */
1847                         may_free = __dispose_buffer(jh, transaction);
1848                         goto zap_buffer;
1849                 }
1850                 /*
1851                  * If it is committing, we simply cannot touch it.  We
1852                  * can remove it's next_transaction pointer from the
1853                  * running transaction if that is set, but nothing
1854                  * else. */
1855                 set_buffer_freed(bh);
1856                 if (jh->b_next_transaction) {
1857                         J_ASSERT(jh->b_next_transaction ==
1858                                         journal->j_running_transaction);
1859                         jh->b_next_transaction = NULL;
1860                 }
1861                 jbd2_journal_put_journal_head(jh);
1862                 spin_unlock(&journal->j_list_lock);
1863                 jbd_unlock_bh_state(bh);
1864                 spin_unlock(&journal->j_state_lock);
1865                 return 0;
1866         } else {
1867                 /* Good, the buffer belongs to the running transaction.
1868                  * We are writing our own transaction's data, not any
1869                  * previous one's, so it is safe to throw it away
1870                  * (remember that we expect the filesystem to have set
1871                  * i_size already for this truncate so recovery will not
1872                  * expose the disk blocks we are discarding here.) */
1873                 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
1874                 JBUFFER_TRACE(jh, "on running transaction");
1875                 may_free = __dispose_buffer(jh, transaction);
1876         }
1877
1878 zap_buffer:
1879         jbd2_journal_put_journal_head(jh);
1880 zap_buffer_no_jh:
1881         spin_unlock(&journal->j_list_lock);
1882         jbd_unlock_bh_state(bh);
1883         spin_unlock(&journal->j_state_lock);
1884 zap_buffer_unlocked:
1885         clear_buffer_dirty(bh);
1886         J_ASSERT_BH(bh, !buffer_jbddirty(bh));
1887         clear_buffer_mapped(bh);
1888         clear_buffer_req(bh);
1889         clear_buffer_new(bh);
1890         bh->b_bdev = NULL;
1891         return may_free;
1892 }
1893
1894 /**
1895  * void jbd2_journal_invalidatepage()
1896  * @journal: journal to use for flush...
1897  * @page:    page to flush
1898  * @offset:  length of page to invalidate.
1899  *
1900  * Reap page buffers containing data after offset in page.
1901  *
1902  */
1903 void jbd2_journal_invalidatepage(journal_t *journal,
1904                       struct page *page,
1905                       unsigned long offset)
1906 {
1907         struct buffer_head *head, *bh, *next;
1908         unsigned int curr_off = 0;
1909         int may_free = 1;
1910
1911         if (!PageLocked(page))
1912                 BUG();
1913         if (!page_has_buffers(page))
1914                 return;
1915
1916         /* We will potentially be playing with lists other than just the
1917          * data lists (especially for journaled data mode), so be
1918          * cautious in our locking. */
1919
1920         head = bh = page_buffers(page);
1921         do {
1922                 unsigned int next_off = curr_off + bh->b_size;
1923                 next = bh->b_this_page;
1924
1925                 if (offset <= curr_off) {
1926                         /* This block is wholly outside the truncation point */
1927                         lock_buffer(bh);
1928                         may_free &= journal_unmap_buffer(journal, bh);
1929                         unlock_buffer(bh);
1930                 }
1931                 curr_off = next_off;
1932                 bh = next;
1933
1934         } while (bh != head);
1935
1936         if (!offset) {
1937                 if (may_free && try_to_free_buffers(page))
1938                         J_ASSERT(!page_has_buffers(page));
1939         }
1940 }
1941
1942 /*
1943  * File a buffer on the given transaction list.
1944  */
1945 void __jbd2_journal_file_buffer(struct journal_head *jh,
1946                         transaction_t *transaction, int jlist)
1947 {
1948         struct journal_head **list = NULL;
1949         int was_dirty = 0;
1950         struct buffer_head *bh = jh2bh(jh);
1951
1952         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1953         assert_spin_locked(&transaction->t_journal->j_list_lock);
1954
1955         J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1956         J_ASSERT_JH(jh, jh->b_transaction == transaction ||
1957                                 jh->b_transaction == 0);
1958
1959         if (jh->b_transaction && jh->b_jlist == jlist)
1960                 return;
1961
1962         /* The following list of buffer states needs to be consistent
1963          * with __jbd_unexpected_dirty_buffer()'s handling of dirty
1964          * state. */
1965
1966         if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
1967             jlist == BJ_Shadow || jlist == BJ_Forget) {
1968                 if (test_clear_buffer_dirty(bh) ||
1969                     test_clear_buffer_jbddirty(bh))
1970                         was_dirty = 1;
1971         }
1972
1973         if (jh->b_transaction)
1974                 __jbd2_journal_temp_unlink_buffer(jh);
1975         jh->b_transaction = transaction;
1976
1977         switch (jlist) {
1978         case BJ_None:
1979                 J_ASSERT_JH(jh, !jh->b_committed_data);
1980                 J_ASSERT_JH(jh, !jh->b_frozen_data);
1981                 return;
1982         case BJ_SyncData:
1983                 list = &transaction->t_sync_datalist;
1984                 break;
1985         case BJ_Metadata:
1986                 transaction->t_nr_buffers++;
1987                 list = &transaction->t_buffers;
1988                 break;
1989         case BJ_Forget:
1990                 list = &transaction->t_forget;
1991                 break;
1992         case BJ_IO:
1993                 list = &transaction->t_iobuf_list;
1994                 break;
1995         case BJ_Shadow:
1996                 list = &transaction->t_shadow_list;
1997                 break;
1998         case BJ_LogCtl:
1999                 list = &transaction->t_log_list;
2000                 break;
2001         case BJ_Reserved:
2002                 list = &transaction->t_reserved_list;
2003                 break;
2004         case BJ_Locked:
2005                 list =  &transaction->t_locked_list;
2006                 break;
2007         }
2008
2009         __blist_add_buffer(list, jh);
2010         jh->b_jlist = jlist;
2011
2012         if (was_dirty)
2013                 set_buffer_jbddirty(bh);
2014 }
2015
2016 void jbd2_journal_file_buffer(struct journal_head *jh,
2017                                 transaction_t *transaction, int jlist)
2018 {
2019         jbd_lock_bh_state(jh2bh(jh));
2020         spin_lock(&transaction->t_journal->j_list_lock);
2021         __jbd2_journal_file_buffer(jh, transaction, jlist);
2022         spin_unlock(&transaction->t_journal->j_list_lock);
2023         jbd_unlock_bh_state(jh2bh(jh));
2024 }
2025
2026 /*
2027  * Remove a buffer from its current buffer list in preparation for
2028  * dropping it from its current transaction entirely.  If the buffer has
2029  * already started to be used by a subsequent transaction, refile the
2030  * buffer on that transaction's metadata list.
2031  *
2032  * Called under journal->j_list_lock
2033  *
2034  * Called under jbd_lock_bh_state(jh2bh(jh))
2035  */
2036 void __jbd2_journal_refile_buffer(struct journal_head *jh)
2037 {
2038         int was_dirty;
2039         struct buffer_head *bh = jh2bh(jh);
2040
2041         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2042         if (jh->b_transaction)
2043                 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2044
2045         /* If the buffer is now unused, just drop it. */
2046         if (jh->b_next_transaction == NULL) {
2047                 __jbd2_journal_unfile_buffer(jh);
2048                 return;
2049         }
2050
2051         /*
2052          * It has been modified by a later transaction: add it to the new
2053          * transaction's metadata list.
2054          */
2055
2056         was_dirty = test_clear_buffer_jbddirty(bh);
2057         __jbd2_journal_temp_unlink_buffer(jh);
2058         jh->b_transaction = jh->b_next_transaction;
2059         jh->b_next_transaction = NULL;
2060         __jbd2_journal_file_buffer(jh, jh->b_transaction,
2061                                 was_dirty ? BJ_Metadata : BJ_Reserved);
2062         J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2063
2064         if (was_dirty)
2065                 set_buffer_jbddirty(bh);
2066 }
2067
2068 /*
2069  * For the unlocked version of this call, also make sure that any
2070  * hanging journal_head is cleaned up if necessary.
2071  *
2072  * __jbd2_journal_refile_buffer is usually called as part of a single locked
2073  * operation on a buffer_head, in which the caller is probably going to
2074  * be hooking the journal_head onto other lists.  In that case it is up
2075  * to the caller to remove the journal_head if necessary.  For the
2076  * unlocked jbd2_journal_refile_buffer call, the caller isn't going to be
2077  * doing anything else to the buffer so we need to do the cleanup
2078  * ourselves to avoid a jh leak.
2079  *
2080  * *** The journal_head may be freed by this call! ***
2081  */
2082 void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2083 {
2084         struct buffer_head *bh = jh2bh(jh);
2085
2086         jbd_lock_bh_state(bh);
2087         spin_lock(&journal->j_list_lock);
2088
2089         __jbd2_journal_refile_buffer(jh);
2090         jbd_unlock_bh_state(bh);
2091         jbd2_journal_remove_journal_head(bh);
2092
2093         spin_unlock(&journal->j_list_lock);
2094         __brelse(bh);
2095 }