mm: Remove slab destructors from kmem_cache_create().
[linux-2.6.git] / fs / jbd / journal.c
1 /*
2  * linux/fs/jbd/journal.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 journal-writing code; part of the ext2fs
13  * journaling system.
14  *
15  * This file manages journals: areas of disk reserved for logging
16  * transactional updates.  This includes the kernel journaling thread
17  * which is responsible for scheduling updates to the log.
18  *
19  * We do not actually manage the physical storage of the journal in this
20  * file: that is left to a per-journal policy function, which allows us
21  * to store the journal within a filesystem-specified area for ext2
22  * journaling (ext2 can use a reserved inode for storing the log).
23  */
24
25 #include <linux/module.h>
26 #include <linux/time.h>
27 #include <linux/fs.h>
28 #include <linux/jbd.h>
29 #include <linux/errno.h>
30 #include <linux/slab.h>
31 #include <linux/init.h>
32 #include <linux/mm.h>
33 #include <linux/freezer.h>
34 #include <linux/pagemap.h>
35 #include <linux/kthread.h>
36 #include <linux/poison.h>
37 #include <linux/proc_fs.h>
38
39 #include <asm/uaccess.h>
40 #include <asm/page.h>
41
42 EXPORT_SYMBOL(journal_start);
43 EXPORT_SYMBOL(journal_restart);
44 EXPORT_SYMBOL(journal_extend);
45 EXPORT_SYMBOL(journal_stop);
46 EXPORT_SYMBOL(journal_lock_updates);
47 EXPORT_SYMBOL(journal_unlock_updates);
48 EXPORT_SYMBOL(journal_get_write_access);
49 EXPORT_SYMBOL(journal_get_create_access);
50 EXPORT_SYMBOL(journal_get_undo_access);
51 EXPORT_SYMBOL(journal_dirty_data);
52 EXPORT_SYMBOL(journal_dirty_metadata);
53 EXPORT_SYMBOL(journal_release_buffer);
54 EXPORT_SYMBOL(journal_forget);
55 #if 0
56 EXPORT_SYMBOL(journal_sync_buffer);
57 #endif
58 EXPORT_SYMBOL(journal_flush);
59 EXPORT_SYMBOL(journal_revoke);
60
61 EXPORT_SYMBOL(journal_init_dev);
62 EXPORT_SYMBOL(journal_init_inode);
63 EXPORT_SYMBOL(journal_update_format);
64 EXPORT_SYMBOL(journal_check_used_features);
65 EXPORT_SYMBOL(journal_check_available_features);
66 EXPORT_SYMBOL(journal_set_features);
67 EXPORT_SYMBOL(journal_create);
68 EXPORT_SYMBOL(journal_load);
69 EXPORT_SYMBOL(journal_destroy);
70 EXPORT_SYMBOL(journal_update_superblock);
71 EXPORT_SYMBOL(journal_abort);
72 EXPORT_SYMBOL(journal_errno);
73 EXPORT_SYMBOL(journal_ack_err);
74 EXPORT_SYMBOL(journal_clear_err);
75 EXPORT_SYMBOL(log_wait_commit);
76 EXPORT_SYMBOL(journal_start_commit);
77 EXPORT_SYMBOL(journal_force_commit_nested);
78 EXPORT_SYMBOL(journal_wipe);
79 EXPORT_SYMBOL(journal_blocks_per_page);
80 EXPORT_SYMBOL(journal_invalidatepage);
81 EXPORT_SYMBOL(journal_try_to_free_buffers);
82 EXPORT_SYMBOL(journal_force_commit);
83
84 static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *);
85 static void __journal_abort_soft (journal_t *journal, int errno);
86 static int journal_create_jbd_slab(size_t slab_size);
87
88 /*
89  * Helper function used to manage commit timeouts
90  */
91
92 static void commit_timeout(unsigned long __data)
93 {
94         struct task_struct * p = (struct task_struct *) __data;
95
96         wake_up_process(p);
97 }
98
99 /*
100  * kjournald: The main thread function used to manage a logging device
101  * journal.
102  *
103  * This kernel thread is responsible for two things:
104  *
105  * 1) COMMIT:  Every so often we need to commit the current state of the
106  *    filesystem to disk.  The journal thread is responsible for writing
107  *    all of the metadata buffers to disk.
108  *
109  * 2) CHECKPOINT: We cannot reuse a used section of the log file until all
110  *    of the data in that part of the log has been rewritten elsewhere on
111  *    the disk.  Flushing these old buffers to reclaim space in the log is
112  *    known as checkpointing, and this thread is responsible for that job.
113  */
114
115 static int kjournald(void *arg)
116 {
117         journal_t *journal = arg;
118         transaction_t *transaction;
119
120         /*
121          * Set up an interval timer which can be used to trigger a commit wakeup
122          * after the commit interval expires
123          */
124         setup_timer(&journal->j_commit_timer, commit_timeout,
125                         (unsigned long)current);
126
127         /* Record that the journal thread is running */
128         journal->j_task = current;
129         wake_up(&journal->j_wait_done_commit);
130
131         printk(KERN_INFO "kjournald starting.  Commit interval %ld seconds\n",
132                         journal->j_commit_interval / HZ);
133
134         /*
135          * And now, wait forever for commit wakeup events.
136          */
137         spin_lock(&journal->j_state_lock);
138
139 loop:
140         if (journal->j_flags & JFS_UNMOUNT)
141                 goto end_loop;
142
143         jbd_debug(1, "commit_sequence=%d, commit_request=%d\n",
144                 journal->j_commit_sequence, journal->j_commit_request);
145
146         if (journal->j_commit_sequence != journal->j_commit_request) {
147                 jbd_debug(1, "OK, requests differ\n");
148                 spin_unlock(&journal->j_state_lock);
149                 del_timer_sync(&journal->j_commit_timer);
150                 journal_commit_transaction(journal);
151                 spin_lock(&journal->j_state_lock);
152                 goto loop;
153         }
154
155         wake_up(&journal->j_wait_done_commit);
156         if (freezing(current)) {
157                 /*
158                  * The simpler the better. Flushing journal isn't a
159                  * good idea, because that depends on threads that may
160                  * be already stopped.
161                  */
162                 jbd_debug(1, "Now suspending kjournald\n");
163                 spin_unlock(&journal->j_state_lock);
164                 refrigerator();
165                 spin_lock(&journal->j_state_lock);
166         } else {
167                 /*
168                  * We assume on resume that commits are already there,
169                  * so we don't sleep
170                  */
171                 DEFINE_WAIT(wait);
172                 int should_sleep = 1;
173
174                 prepare_to_wait(&journal->j_wait_commit, &wait,
175                                 TASK_INTERRUPTIBLE);
176                 if (journal->j_commit_sequence != journal->j_commit_request)
177                         should_sleep = 0;
178                 transaction = journal->j_running_transaction;
179                 if (transaction && time_after_eq(jiffies,
180                                                 transaction->t_expires))
181                         should_sleep = 0;
182                 if (journal->j_flags & JFS_UNMOUNT)
183                         should_sleep = 0;
184                 if (should_sleep) {
185                         spin_unlock(&journal->j_state_lock);
186                         schedule();
187                         spin_lock(&journal->j_state_lock);
188                 }
189                 finish_wait(&journal->j_wait_commit, &wait);
190         }
191
192         jbd_debug(1, "kjournald wakes\n");
193
194         /*
195          * Were we woken up by a commit wakeup event?
196          */
197         transaction = journal->j_running_transaction;
198         if (transaction && time_after_eq(jiffies, transaction->t_expires)) {
199                 journal->j_commit_request = transaction->t_tid;
200                 jbd_debug(1, "woke because of timeout\n");
201         }
202         goto loop;
203
204 end_loop:
205         spin_unlock(&journal->j_state_lock);
206         del_timer_sync(&journal->j_commit_timer);
207         journal->j_task = NULL;
208         wake_up(&journal->j_wait_done_commit);
209         jbd_debug(1, "Journal thread exiting.\n");
210         return 0;
211 }
212
213 static int journal_start_thread(journal_t *journal)
214 {
215         struct task_struct *t;
216
217         t = kthread_run(kjournald, journal, "kjournald");
218         if (IS_ERR(t))
219                 return PTR_ERR(t);
220
221         wait_event(journal->j_wait_done_commit, journal->j_task != 0);
222         return 0;
223 }
224
225 static void journal_kill_thread(journal_t *journal)
226 {
227         spin_lock(&journal->j_state_lock);
228         journal->j_flags |= JFS_UNMOUNT;
229
230         while (journal->j_task) {
231                 wake_up(&journal->j_wait_commit);
232                 spin_unlock(&journal->j_state_lock);
233                 wait_event(journal->j_wait_done_commit, journal->j_task == 0);
234                 spin_lock(&journal->j_state_lock);
235         }
236         spin_unlock(&journal->j_state_lock);
237 }
238
239 /*
240  * journal_write_metadata_buffer: write a metadata buffer to the journal.
241  *
242  * Writes a metadata buffer to a given disk block.  The actual IO is not
243  * performed but a new buffer_head is constructed which labels the data
244  * to be written with the correct destination disk block.
245  *
246  * Any magic-number escaping which needs to be done will cause a
247  * copy-out here.  If the buffer happens to start with the
248  * JFS_MAGIC_NUMBER, then we can't write it to the log directly: the
249  * magic number is only written to the log for descripter blocks.  In
250  * this case, we copy the data and replace the first word with 0, and we
251  * return a result code which indicates that this buffer needs to be
252  * marked as an escaped buffer in the corresponding log descriptor
253  * block.  The missing word can then be restored when the block is read
254  * during recovery.
255  *
256  * If the source buffer has already been modified by a new transaction
257  * since we took the last commit snapshot, we use the frozen copy of
258  * that data for IO.  If we end up using the existing buffer_head's data
259  * for the write, then we *have* to lock the buffer to prevent anyone
260  * else from using and possibly modifying it while the IO is in
261  * progress.
262  *
263  * The function returns a pointer to the buffer_heads to be used for IO.
264  *
265  * We assume that the journal has already been locked in this function.
266  *
267  * Return value:
268  *  <0: Error
269  * >=0: Finished OK
270  *
271  * On success:
272  * Bit 0 set == escape performed on the data
273  * Bit 1 set == buffer copy-out performed (kfree the data after IO)
274  */
275
276 int journal_write_metadata_buffer(transaction_t *transaction,
277                                   struct journal_head  *jh_in,
278                                   struct journal_head **jh_out,
279                                   unsigned long blocknr)
280 {
281         int need_copy_out = 0;
282         int done_copy_out = 0;
283         int do_escape = 0;
284         char *mapped_data;
285         struct buffer_head *new_bh;
286         struct journal_head *new_jh;
287         struct page *new_page;
288         unsigned int new_offset;
289         struct buffer_head *bh_in = jh2bh(jh_in);
290
291         /*
292          * The buffer really shouldn't be locked: only the current committing
293          * transaction is allowed to write it, so nobody else is allowed
294          * to do any IO.
295          *
296          * akpm: except if we're journalling data, and write() output is
297          * also part of a shared mapping, and another thread has
298          * decided to launch a writepage() against this buffer.
299          */
300         J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in));
301
302         new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL);
303
304         /*
305          * If a new transaction has already done a buffer copy-out, then
306          * we use that version of the data for the commit.
307          */
308         jbd_lock_bh_state(bh_in);
309 repeat:
310         if (jh_in->b_frozen_data) {
311                 done_copy_out = 1;
312                 new_page = virt_to_page(jh_in->b_frozen_data);
313                 new_offset = offset_in_page(jh_in->b_frozen_data);
314         } else {
315                 new_page = jh2bh(jh_in)->b_page;
316                 new_offset = offset_in_page(jh2bh(jh_in)->b_data);
317         }
318
319         mapped_data = kmap_atomic(new_page, KM_USER0);
320         /*
321          * Check for escaping
322          */
323         if (*((__be32 *)(mapped_data + new_offset)) ==
324                                 cpu_to_be32(JFS_MAGIC_NUMBER)) {
325                 need_copy_out = 1;
326                 do_escape = 1;
327         }
328         kunmap_atomic(mapped_data, KM_USER0);
329
330         /*
331          * Do we need to do a data copy?
332          */
333         if (need_copy_out && !done_copy_out) {
334                 char *tmp;
335
336                 jbd_unlock_bh_state(bh_in);
337                 tmp = jbd_slab_alloc(bh_in->b_size, GFP_NOFS);
338                 jbd_lock_bh_state(bh_in);
339                 if (jh_in->b_frozen_data) {
340                         jbd_slab_free(tmp, bh_in->b_size);
341                         goto repeat;
342                 }
343
344                 jh_in->b_frozen_data = tmp;
345                 mapped_data = kmap_atomic(new_page, KM_USER0);
346                 memcpy(tmp, mapped_data + new_offset, jh2bh(jh_in)->b_size);
347                 kunmap_atomic(mapped_data, KM_USER0);
348
349                 new_page = virt_to_page(tmp);
350                 new_offset = offset_in_page(tmp);
351                 done_copy_out = 1;
352         }
353
354         /*
355          * Did we need to do an escaping?  Now we've done all the
356          * copying, we can finally do so.
357          */
358         if (do_escape) {
359                 mapped_data = kmap_atomic(new_page, KM_USER0);
360                 *((unsigned int *)(mapped_data + new_offset)) = 0;
361                 kunmap_atomic(mapped_data, KM_USER0);
362         }
363
364         /* keep subsequent assertions sane */
365         new_bh->b_state = 0;
366         init_buffer(new_bh, NULL, NULL);
367         atomic_set(&new_bh->b_count, 1);
368         jbd_unlock_bh_state(bh_in);
369
370         new_jh = journal_add_journal_head(new_bh);      /* This sleeps */
371
372         set_bh_page(new_bh, new_page, new_offset);
373         new_jh->b_transaction = NULL;
374         new_bh->b_size = jh2bh(jh_in)->b_size;
375         new_bh->b_bdev = transaction->t_journal->j_dev;
376         new_bh->b_blocknr = blocknr;
377         set_buffer_mapped(new_bh);
378         set_buffer_dirty(new_bh);
379
380         *jh_out = new_jh;
381
382         /*
383          * The to-be-written buffer needs to get moved to the io queue,
384          * and the original buffer whose contents we are shadowing or
385          * copying is moved to the transaction's shadow queue.
386          */
387         JBUFFER_TRACE(jh_in, "file as BJ_Shadow");
388         journal_file_buffer(jh_in, transaction, BJ_Shadow);
389         JBUFFER_TRACE(new_jh, "file as BJ_IO");
390         journal_file_buffer(new_jh, transaction, BJ_IO);
391
392         return do_escape | (done_copy_out << 1);
393 }
394
395 /*
396  * Allocation code for the journal file.  Manage the space left in the
397  * journal, so that we can begin checkpointing when appropriate.
398  */
399
400 /*
401  * __log_space_left: Return the number of free blocks left in the journal.
402  *
403  * Called with the journal already locked.
404  *
405  * Called under j_state_lock
406  */
407
408 int __log_space_left(journal_t *journal)
409 {
410         int left = journal->j_free;
411
412         assert_spin_locked(&journal->j_state_lock);
413
414         /*
415          * Be pessimistic here about the number of those free blocks which
416          * might be required for log descriptor control blocks.
417          */
418
419 #define MIN_LOG_RESERVED_BLOCKS 32 /* Allow for rounding errors */
420
421         left -= MIN_LOG_RESERVED_BLOCKS;
422
423         if (left <= 0)
424                 return 0;
425         left -= (left >> 3);
426         return left;
427 }
428
429 /*
430  * Called under j_state_lock.  Returns true if a transaction was started.
431  */
432 int __log_start_commit(journal_t *journal, tid_t target)
433 {
434         /*
435          * Are we already doing a recent enough commit?
436          */
437         if (!tid_geq(journal->j_commit_request, target)) {
438                 /*
439                  * We want a new commit: OK, mark the request and wakup the
440                  * commit thread.  We do _not_ do the commit ourselves.
441                  */
442
443                 journal->j_commit_request = target;
444                 jbd_debug(1, "JBD: requesting commit %d/%d\n",
445                           journal->j_commit_request,
446                           journal->j_commit_sequence);
447                 wake_up(&journal->j_wait_commit);
448                 return 1;
449         }
450         return 0;
451 }
452
453 int log_start_commit(journal_t *journal, tid_t tid)
454 {
455         int ret;
456
457         spin_lock(&journal->j_state_lock);
458         ret = __log_start_commit(journal, tid);
459         spin_unlock(&journal->j_state_lock);
460         return ret;
461 }
462
463 /*
464  * Force and wait upon a commit if the calling process is not within
465  * transaction.  This is used for forcing out undo-protected data which contains
466  * bitmaps, when the fs is running out of space.
467  *
468  * We can only force the running transaction if we don't have an active handle;
469  * otherwise, we will deadlock.
470  *
471  * Returns true if a transaction was started.
472  */
473 int journal_force_commit_nested(journal_t *journal)
474 {
475         transaction_t *transaction = NULL;
476         tid_t tid;
477
478         spin_lock(&journal->j_state_lock);
479         if (journal->j_running_transaction && !current->journal_info) {
480                 transaction = journal->j_running_transaction;
481                 __log_start_commit(journal, transaction->t_tid);
482         } else if (journal->j_committing_transaction)
483                 transaction = journal->j_committing_transaction;
484
485         if (!transaction) {
486                 spin_unlock(&journal->j_state_lock);
487                 return 0;       /* Nothing to retry */
488         }
489
490         tid = transaction->t_tid;
491         spin_unlock(&journal->j_state_lock);
492         log_wait_commit(journal, tid);
493         return 1;
494 }
495
496 /*
497  * Start a commit of the current running transaction (if any).  Returns true
498  * if a transaction was started, and fills its tid in at *ptid
499  */
500 int journal_start_commit(journal_t *journal, tid_t *ptid)
501 {
502         int ret = 0;
503
504         spin_lock(&journal->j_state_lock);
505         if (journal->j_running_transaction) {
506                 tid_t tid = journal->j_running_transaction->t_tid;
507
508                 ret = __log_start_commit(journal, tid);
509                 if (ret && ptid)
510                         *ptid = tid;
511         } else if (journal->j_committing_transaction && ptid) {
512                 /*
513                  * If ext3_write_super() recently started a commit, then we
514                  * have to wait for completion of that transaction
515                  */
516                 *ptid = journal->j_committing_transaction->t_tid;
517                 ret = 1;
518         }
519         spin_unlock(&journal->j_state_lock);
520         return ret;
521 }
522
523 /*
524  * Wait for a specified commit to complete.
525  * The caller may not hold the journal lock.
526  */
527 int log_wait_commit(journal_t *journal, tid_t tid)
528 {
529         int err = 0;
530
531 #ifdef CONFIG_JBD_DEBUG
532         spin_lock(&journal->j_state_lock);
533         if (!tid_geq(journal->j_commit_request, tid)) {
534                 printk(KERN_EMERG
535                        "%s: error: j_commit_request=%d, tid=%d\n",
536                        __FUNCTION__, journal->j_commit_request, tid);
537         }
538         spin_unlock(&journal->j_state_lock);
539 #endif
540         spin_lock(&journal->j_state_lock);
541         while (tid_gt(tid, journal->j_commit_sequence)) {
542                 jbd_debug(1, "JBD: want %d, j_commit_sequence=%d\n",
543                                   tid, journal->j_commit_sequence);
544                 wake_up(&journal->j_wait_commit);
545                 spin_unlock(&journal->j_state_lock);
546                 wait_event(journal->j_wait_done_commit,
547                                 !tid_gt(tid, journal->j_commit_sequence));
548                 spin_lock(&journal->j_state_lock);
549         }
550         spin_unlock(&journal->j_state_lock);
551
552         if (unlikely(is_journal_aborted(journal))) {
553                 printk(KERN_EMERG "journal commit I/O error\n");
554                 err = -EIO;
555         }
556         return err;
557 }
558
559 /*
560  * Log buffer allocation routines:
561  */
562
563 int journal_next_log_block(journal_t *journal, unsigned long *retp)
564 {
565         unsigned long blocknr;
566
567         spin_lock(&journal->j_state_lock);
568         J_ASSERT(journal->j_free > 1);
569
570         blocknr = journal->j_head;
571         journal->j_head++;
572         journal->j_free--;
573         if (journal->j_head == journal->j_last)
574                 journal->j_head = journal->j_first;
575         spin_unlock(&journal->j_state_lock);
576         return journal_bmap(journal, blocknr, retp);
577 }
578
579 /*
580  * Conversion of logical to physical block numbers for the journal
581  *
582  * On external journals the journal blocks are identity-mapped, so
583  * this is a no-op.  If needed, we can use j_blk_offset - everything is
584  * ready.
585  */
586 int journal_bmap(journal_t *journal, unsigned long blocknr,
587                  unsigned long *retp)
588 {
589         int err = 0;
590         unsigned long ret;
591
592         if (journal->j_inode) {
593                 ret = bmap(journal->j_inode, blocknr);
594                 if (ret)
595                         *retp = ret;
596                 else {
597                         char b[BDEVNAME_SIZE];
598
599                         printk(KERN_ALERT "%s: journal block not found "
600                                         "at offset %lu on %s\n",
601                                 __FUNCTION__,
602                                 blocknr,
603                                 bdevname(journal->j_dev, b));
604                         err = -EIO;
605                         __journal_abort_soft(journal, err);
606                 }
607         } else {
608                 *retp = blocknr; /* +journal->j_blk_offset */
609         }
610         return err;
611 }
612
613 /*
614  * We play buffer_head aliasing tricks to write data/metadata blocks to
615  * the journal without copying their contents, but for journal
616  * descriptor blocks we do need to generate bona fide buffers.
617  *
618  * After the caller of journal_get_descriptor_buffer() has finished modifying
619  * the buffer's contents they really should run flush_dcache_page(bh->b_page).
620  * But we don't bother doing that, so there will be coherency problems with
621  * mmaps of blockdevs which hold live JBD-controlled filesystems.
622  */
623 struct journal_head *journal_get_descriptor_buffer(journal_t *journal)
624 {
625         struct buffer_head *bh;
626         unsigned long blocknr;
627         int err;
628
629         err = journal_next_log_block(journal, &blocknr);
630
631         if (err)
632                 return NULL;
633
634         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
635         lock_buffer(bh);
636         memset(bh->b_data, 0, journal->j_blocksize);
637         set_buffer_uptodate(bh);
638         unlock_buffer(bh);
639         BUFFER_TRACE(bh, "return this buffer");
640         return journal_add_journal_head(bh);
641 }
642
643 /*
644  * Management for journal control blocks: functions to create and
645  * destroy journal_t structures, and to initialise and read existing
646  * journal blocks from disk.  */
647
648 /* First: create and setup a journal_t object in memory.  We initialise
649  * very few fields yet: that has to wait until we have created the
650  * journal structures from from scratch, or loaded them from disk. */
651
652 static journal_t * journal_init_common (void)
653 {
654         journal_t *journal;
655         int err;
656
657         journal = jbd_kmalloc(sizeof(*journal), GFP_KERNEL);
658         if (!journal)
659                 goto fail;
660         memset(journal, 0, sizeof(*journal));
661
662         init_waitqueue_head(&journal->j_wait_transaction_locked);
663         init_waitqueue_head(&journal->j_wait_logspace);
664         init_waitqueue_head(&journal->j_wait_done_commit);
665         init_waitqueue_head(&journal->j_wait_checkpoint);
666         init_waitqueue_head(&journal->j_wait_commit);
667         init_waitqueue_head(&journal->j_wait_updates);
668         mutex_init(&journal->j_barrier);
669         mutex_init(&journal->j_checkpoint_mutex);
670         spin_lock_init(&journal->j_revoke_lock);
671         spin_lock_init(&journal->j_list_lock);
672         spin_lock_init(&journal->j_state_lock);
673
674         journal->j_commit_interval = (HZ * JBD_DEFAULT_MAX_COMMIT_AGE);
675
676         /* The journal is marked for error until we succeed with recovery! */
677         journal->j_flags = JFS_ABORT;
678
679         /* Set up a default-sized revoke table for the new mount. */
680         err = journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH);
681         if (err) {
682                 kfree(journal);
683                 goto fail;
684         }
685         return journal;
686 fail:
687         return NULL;
688 }
689
690 /* journal_init_dev and journal_init_inode:
691  *
692  * Create a journal structure assigned some fixed set of disk blocks to
693  * the journal.  We don't actually touch those disk blocks yet, but we
694  * need to set up all of the mapping information to tell the journaling
695  * system where the journal blocks are.
696  *
697  */
698
699 /**
700  *  journal_t * journal_init_dev() - creates an initialises a journal structure
701  *  @bdev: Block device on which to create the journal
702  *  @fs_dev: Device which hold journalled filesystem for this journal.
703  *  @start: Block nr Start of journal.
704  *  @len:  Length of the journal in blocks.
705  *  @blocksize: blocksize of journalling device
706  *  @returns: a newly created journal_t *
707  *
708  *  journal_init_dev creates a journal which maps a fixed contiguous
709  *  range of blocks on an arbitrary block device.
710  *
711  */
712 journal_t * journal_init_dev(struct block_device *bdev,
713                         struct block_device *fs_dev,
714                         int start, int len, int blocksize)
715 {
716         journal_t *journal = journal_init_common();
717         struct buffer_head *bh;
718         int n;
719
720         if (!journal)
721                 return NULL;
722
723         /* journal descriptor can store up to n blocks -bzzz */
724         journal->j_blocksize = blocksize;
725         n = journal->j_blocksize / sizeof(journal_block_tag_t);
726         journal->j_wbufsize = n;
727         journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
728         if (!journal->j_wbuf) {
729                 printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
730                         __FUNCTION__);
731                 kfree(journal);
732                 journal = NULL;
733                 goto out;
734         }
735         journal->j_dev = bdev;
736         journal->j_fs_dev = fs_dev;
737         journal->j_blk_offset = start;
738         journal->j_maxlen = len;
739
740         bh = __getblk(journal->j_dev, start, journal->j_blocksize);
741         J_ASSERT(bh != NULL);
742         journal->j_sb_buffer = bh;
743         journal->j_superblock = (journal_superblock_t *)bh->b_data;
744 out:
745         return journal;
746 }
747
748 /**
749  *  journal_t * journal_init_inode () - creates a journal which maps to a inode.
750  *  @inode: An inode to create the journal in
751  *
752  * journal_init_inode creates a journal which maps an on-disk inode as
753  * the journal.  The inode must exist already, must support bmap() and
754  * must have all data blocks preallocated.
755  */
756 journal_t * journal_init_inode (struct inode *inode)
757 {
758         struct buffer_head *bh;
759         journal_t *journal = journal_init_common();
760         int err;
761         int n;
762         unsigned long blocknr;
763
764         if (!journal)
765                 return NULL;
766
767         journal->j_dev = journal->j_fs_dev = inode->i_sb->s_bdev;
768         journal->j_inode = inode;
769         jbd_debug(1,
770                   "journal %p: inode %s/%ld, size %Ld, bits %d, blksize %ld\n",
771                   journal, inode->i_sb->s_id, inode->i_ino,
772                   (long long) inode->i_size,
773                   inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize);
774
775         journal->j_maxlen = inode->i_size >> inode->i_sb->s_blocksize_bits;
776         journal->j_blocksize = inode->i_sb->s_blocksize;
777
778         /* journal descriptor can store up to n blocks -bzzz */
779         n = journal->j_blocksize / sizeof(journal_block_tag_t);
780         journal->j_wbufsize = n;
781         journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
782         if (!journal->j_wbuf) {
783                 printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
784                         __FUNCTION__);
785                 kfree(journal);
786                 return NULL;
787         }
788
789         err = journal_bmap(journal, 0, &blocknr);
790         /* If that failed, give up */
791         if (err) {
792                 printk(KERN_ERR "%s: Cannnot locate journal superblock\n",
793                        __FUNCTION__);
794                 kfree(journal);
795                 return NULL;
796         }
797
798         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
799         J_ASSERT(bh != NULL);
800         journal->j_sb_buffer = bh;
801         journal->j_superblock = (journal_superblock_t *)bh->b_data;
802
803         return journal;
804 }
805
806 /*
807  * If the journal init or create aborts, we need to mark the journal
808  * superblock as being NULL to prevent the journal destroy from writing
809  * back a bogus superblock.
810  */
811 static void journal_fail_superblock (journal_t *journal)
812 {
813         struct buffer_head *bh = journal->j_sb_buffer;
814         brelse(bh);
815         journal->j_sb_buffer = NULL;
816 }
817
818 /*
819  * Given a journal_t structure, initialise the various fields for
820  * startup of a new journaling session.  We use this both when creating
821  * a journal, and after recovering an old journal to reset it for
822  * subsequent use.
823  */
824
825 static int journal_reset(journal_t *journal)
826 {
827         journal_superblock_t *sb = journal->j_superblock;
828         unsigned long first, last;
829
830         first = be32_to_cpu(sb->s_first);
831         last = be32_to_cpu(sb->s_maxlen);
832
833         journal->j_first = first;
834         journal->j_last = last;
835
836         journal->j_head = first;
837         journal->j_tail = first;
838         journal->j_free = last - first;
839
840         journal->j_tail_sequence = journal->j_transaction_sequence;
841         journal->j_commit_sequence = journal->j_transaction_sequence - 1;
842         journal->j_commit_request = journal->j_commit_sequence;
843
844         journal->j_max_transaction_buffers = journal->j_maxlen / 4;
845
846         /* Add the dynamic fields and write it to disk. */
847         journal_update_superblock(journal, 1);
848         return journal_start_thread(journal);
849 }
850
851 /**
852  * int journal_create() - Initialise the new journal file
853  * @journal: Journal to create. This structure must have been initialised
854  *
855  * Given a journal_t structure which tells us which disk blocks we can
856  * use, create a new journal superblock and initialise all of the
857  * journal fields from scratch.
858  **/
859 int journal_create(journal_t *journal)
860 {
861         unsigned long blocknr;
862         struct buffer_head *bh;
863         journal_superblock_t *sb;
864         int i, err;
865
866         if (journal->j_maxlen < JFS_MIN_JOURNAL_BLOCKS) {
867                 printk (KERN_ERR "Journal length (%d blocks) too short.\n",
868                         journal->j_maxlen);
869                 journal_fail_superblock(journal);
870                 return -EINVAL;
871         }
872
873         if (journal->j_inode == NULL) {
874                 /*
875                  * We don't know what block to start at!
876                  */
877                 printk(KERN_EMERG
878                        "%s: creation of journal on external device!\n",
879                        __FUNCTION__);
880                 BUG();
881         }
882
883         /* Zero out the entire journal on disk.  We cannot afford to
884            have any blocks on disk beginning with JFS_MAGIC_NUMBER. */
885         jbd_debug(1, "JBD: Zeroing out journal blocks...\n");
886         for (i = 0; i < journal->j_maxlen; i++) {
887                 err = journal_bmap(journal, i, &blocknr);
888                 if (err)
889                         return err;
890                 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
891                 lock_buffer(bh);
892                 memset (bh->b_data, 0, journal->j_blocksize);
893                 BUFFER_TRACE(bh, "marking dirty");
894                 mark_buffer_dirty(bh);
895                 BUFFER_TRACE(bh, "marking uptodate");
896                 set_buffer_uptodate(bh);
897                 unlock_buffer(bh);
898                 __brelse(bh);
899         }
900
901         sync_blockdev(journal->j_dev);
902         jbd_debug(1, "JBD: journal cleared.\n");
903
904         /* OK, fill in the initial static fields in the new superblock */
905         sb = journal->j_superblock;
906
907         sb->s_header.h_magic     = cpu_to_be32(JFS_MAGIC_NUMBER);
908         sb->s_header.h_blocktype = cpu_to_be32(JFS_SUPERBLOCK_V2);
909
910         sb->s_blocksize = cpu_to_be32(journal->j_blocksize);
911         sb->s_maxlen    = cpu_to_be32(journal->j_maxlen);
912         sb->s_first     = cpu_to_be32(1);
913
914         journal->j_transaction_sequence = 1;
915
916         journal->j_flags &= ~JFS_ABORT;
917         journal->j_format_version = 2;
918
919         return journal_reset(journal);
920 }
921
922 /**
923  * void journal_update_superblock() - Update journal sb on disk.
924  * @journal: The journal to update.
925  * @wait: Set to '0' if you don't want to wait for IO completion.
926  *
927  * Update a journal's dynamic superblock fields and write it to disk,
928  * optionally waiting for the IO to complete.
929  */
930 void journal_update_superblock(journal_t *journal, int wait)
931 {
932         journal_superblock_t *sb = journal->j_superblock;
933         struct buffer_head *bh = journal->j_sb_buffer;
934
935         /*
936          * As a special case, if the on-disk copy is already marked as needing
937          * no recovery (s_start == 0) and there are no outstanding transactions
938          * in the filesystem, then we can safely defer the superblock update
939          * until the next commit by setting JFS_FLUSHED.  This avoids
940          * attempting a write to a potential-readonly device.
941          */
942         if (sb->s_start == 0 && journal->j_tail_sequence ==
943                                 journal->j_transaction_sequence) {
944                 jbd_debug(1,"JBD: Skipping superblock update on recovered sb "
945                         "(start %ld, seq %d, errno %d)\n",
946                         journal->j_tail, journal->j_tail_sequence,
947                         journal->j_errno);
948                 goto out;
949         }
950
951         spin_lock(&journal->j_state_lock);
952         jbd_debug(1,"JBD: updating superblock (start %ld, seq %d, errno %d)\n",
953                   journal->j_tail, journal->j_tail_sequence, journal->j_errno);
954
955         sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
956         sb->s_start    = cpu_to_be32(journal->j_tail);
957         sb->s_errno    = cpu_to_be32(journal->j_errno);
958         spin_unlock(&journal->j_state_lock);
959
960         BUFFER_TRACE(bh, "marking dirty");
961         mark_buffer_dirty(bh);
962         if (wait)
963                 sync_dirty_buffer(bh);
964         else
965                 ll_rw_block(SWRITE, 1, &bh);
966
967 out:
968         /* If we have just flushed the log (by marking s_start==0), then
969          * any future commit will have to be careful to update the
970          * superblock again to re-record the true start of the log. */
971
972         spin_lock(&journal->j_state_lock);
973         if (sb->s_start)
974                 journal->j_flags &= ~JFS_FLUSHED;
975         else
976                 journal->j_flags |= JFS_FLUSHED;
977         spin_unlock(&journal->j_state_lock);
978 }
979
980 /*
981  * Read the superblock for a given journal, performing initial
982  * validation of the format.
983  */
984
985 static int journal_get_superblock(journal_t *journal)
986 {
987         struct buffer_head *bh;
988         journal_superblock_t *sb;
989         int err = -EIO;
990
991         bh = journal->j_sb_buffer;
992
993         J_ASSERT(bh != NULL);
994         if (!buffer_uptodate(bh)) {
995                 ll_rw_block(READ, 1, &bh);
996                 wait_on_buffer(bh);
997                 if (!buffer_uptodate(bh)) {
998                         printk (KERN_ERR
999                                 "JBD: IO error reading journal superblock\n");
1000                         goto out;
1001                 }
1002         }
1003
1004         sb = journal->j_superblock;
1005
1006         err = -EINVAL;
1007
1008         if (sb->s_header.h_magic != cpu_to_be32(JFS_MAGIC_NUMBER) ||
1009             sb->s_blocksize != cpu_to_be32(journal->j_blocksize)) {
1010                 printk(KERN_WARNING "JBD: no valid journal superblock found\n");
1011                 goto out;
1012         }
1013
1014         switch(be32_to_cpu(sb->s_header.h_blocktype)) {
1015         case JFS_SUPERBLOCK_V1:
1016                 journal->j_format_version = 1;
1017                 break;
1018         case JFS_SUPERBLOCK_V2:
1019                 journal->j_format_version = 2;
1020                 break;
1021         default:
1022                 printk(KERN_WARNING "JBD: unrecognised superblock format ID\n");
1023                 goto out;
1024         }
1025
1026         if (be32_to_cpu(sb->s_maxlen) < journal->j_maxlen)
1027                 journal->j_maxlen = be32_to_cpu(sb->s_maxlen);
1028         else if (be32_to_cpu(sb->s_maxlen) > journal->j_maxlen) {
1029                 printk (KERN_WARNING "JBD: journal file too short\n");
1030                 goto out;
1031         }
1032
1033         return 0;
1034
1035 out:
1036         journal_fail_superblock(journal);
1037         return err;
1038 }
1039
1040 /*
1041  * Load the on-disk journal superblock and read the key fields into the
1042  * journal_t.
1043  */
1044
1045 static int load_superblock(journal_t *journal)
1046 {
1047         int err;
1048         journal_superblock_t *sb;
1049
1050         err = journal_get_superblock(journal);
1051         if (err)
1052                 return err;
1053
1054         sb = journal->j_superblock;
1055
1056         journal->j_tail_sequence = be32_to_cpu(sb->s_sequence);
1057         journal->j_tail = be32_to_cpu(sb->s_start);
1058         journal->j_first = be32_to_cpu(sb->s_first);
1059         journal->j_last = be32_to_cpu(sb->s_maxlen);
1060         journal->j_errno = be32_to_cpu(sb->s_errno);
1061
1062         return 0;
1063 }
1064
1065
1066 /**
1067  * int journal_load() - Read journal from disk.
1068  * @journal: Journal to act on.
1069  *
1070  * Given a journal_t structure which tells us which disk blocks contain
1071  * a journal, read the journal from disk to initialise the in-memory
1072  * structures.
1073  */
1074 int journal_load(journal_t *journal)
1075 {
1076         int err;
1077         journal_superblock_t *sb;
1078
1079         err = load_superblock(journal);
1080         if (err)
1081                 return err;
1082
1083         sb = journal->j_superblock;
1084         /* If this is a V2 superblock, then we have to check the
1085          * features flags on it. */
1086
1087         if (journal->j_format_version >= 2) {
1088                 if ((sb->s_feature_ro_compat &
1089                      ~cpu_to_be32(JFS_KNOWN_ROCOMPAT_FEATURES)) ||
1090                     (sb->s_feature_incompat &
1091                      ~cpu_to_be32(JFS_KNOWN_INCOMPAT_FEATURES))) {
1092                         printk (KERN_WARNING
1093                                 "JBD: Unrecognised features on journal\n");
1094                         return -EINVAL;
1095                 }
1096         }
1097
1098         /*
1099          * Create a slab for this blocksize
1100          */
1101         err = journal_create_jbd_slab(be32_to_cpu(sb->s_blocksize));
1102         if (err)
1103                 return err;
1104
1105         /* Let the recovery code check whether it needs to recover any
1106          * data from the journal. */
1107         if (journal_recover(journal))
1108                 goto recovery_error;
1109
1110         /* OK, we've finished with the dynamic journal bits:
1111          * reinitialise the dynamic contents of the superblock in memory
1112          * and reset them on disk. */
1113         if (journal_reset(journal))
1114                 goto recovery_error;
1115
1116         journal->j_flags &= ~JFS_ABORT;
1117         journal->j_flags |= JFS_LOADED;
1118         return 0;
1119
1120 recovery_error:
1121         printk (KERN_WARNING "JBD: recovery failed\n");
1122         return -EIO;
1123 }
1124
1125 /**
1126  * void journal_destroy() - Release a journal_t structure.
1127  * @journal: Journal to act on.
1128  *
1129  * Release a journal_t structure once it is no longer in use by the
1130  * journaled object.
1131  */
1132 void journal_destroy(journal_t *journal)
1133 {
1134         /* Wait for the commit thread to wake up and die. */
1135         journal_kill_thread(journal);
1136
1137         /* Force a final log commit */
1138         if (journal->j_running_transaction)
1139                 journal_commit_transaction(journal);
1140
1141         /* Force any old transactions to disk */
1142
1143         /* Totally anal locking here... */
1144         spin_lock(&journal->j_list_lock);
1145         while (journal->j_checkpoint_transactions != NULL) {
1146                 spin_unlock(&journal->j_list_lock);
1147                 log_do_checkpoint(journal);
1148                 spin_lock(&journal->j_list_lock);
1149         }
1150
1151         J_ASSERT(journal->j_running_transaction == NULL);
1152         J_ASSERT(journal->j_committing_transaction == NULL);
1153         J_ASSERT(journal->j_checkpoint_transactions == NULL);
1154         spin_unlock(&journal->j_list_lock);
1155
1156         /* We can now mark the journal as empty. */
1157         journal->j_tail = 0;
1158         journal->j_tail_sequence = ++journal->j_transaction_sequence;
1159         if (journal->j_sb_buffer) {
1160                 journal_update_superblock(journal, 1);
1161                 brelse(journal->j_sb_buffer);
1162         }
1163
1164         if (journal->j_inode)
1165                 iput(journal->j_inode);
1166         if (journal->j_revoke)
1167                 journal_destroy_revoke(journal);
1168         kfree(journal->j_wbuf);
1169         kfree(journal);
1170 }
1171
1172
1173 /**
1174  *int journal_check_used_features () - Check if features specified are used.
1175  * @journal: Journal to check.
1176  * @compat: bitmask of compatible features
1177  * @ro: bitmask of features that force read-only mount
1178  * @incompat: bitmask of incompatible features
1179  *
1180  * Check whether the journal uses all of a given set of
1181  * features.  Return true (non-zero) if it does.
1182  **/
1183
1184 int journal_check_used_features (journal_t *journal, unsigned long compat,
1185                                  unsigned long ro, unsigned long incompat)
1186 {
1187         journal_superblock_t *sb;
1188
1189         if (!compat && !ro && !incompat)
1190                 return 1;
1191         if (journal->j_format_version == 1)
1192                 return 0;
1193
1194         sb = journal->j_superblock;
1195
1196         if (((be32_to_cpu(sb->s_feature_compat) & compat) == compat) &&
1197             ((be32_to_cpu(sb->s_feature_ro_compat) & ro) == ro) &&
1198             ((be32_to_cpu(sb->s_feature_incompat) & incompat) == incompat))
1199                 return 1;
1200
1201         return 0;
1202 }
1203
1204 /**
1205  * int journal_check_available_features() - Check feature set in journalling layer
1206  * @journal: Journal to check.
1207  * @compat: bitmask of compatible features
1208  * @ro: bitmask of features that force read-only mount
1209  * @incompat: bitmask of incompatible features
1210  *
1211  * Check whether the journaling code supports the use of
1212  * all of a given set of features on this journal.  Return true
1213  * (non-zero) if it can. */
1214
1215 int journal_check_available_features (journal_t *journal, unsigned long compat,
1216                                       unsigned long ro, unsigned long incompat)
1217 {
1218         journal_superblock_t *sb;
1219
1220         if (!compat && !ro && !incompat)
1221                 return 1;
1222
1223         sb = journal->j_superblock;
1224
1225         /* We can support any known requested features iff the
1226          * superblock is in version 2.  Otherwise we fail to support any
1227          * extended sb features. */
1228
1229         if (journal->j_format_version != 2)
1230                 return 0;
1231
1232         if ((compat   & JFS_KNOWN_COMPAT_FEATURES) == compat &&
1233             (ro       & JFS_KNOWN_ROCOMPAT_FEATURES) == ro &&
1234             (incompat & JFS_KNOWN_INCOMPAT_FEATURES) == incompat)
1235                 return 1;
1236
1237         return 0;
1238 }
1239
1240 /**
1241  * int journal_set_features () - Mark a given journal feature in the superblock
1242  * @journal: Journal to act on.
1243  * @compat: bitmask of compatible features
1244  * @ro: bitmask of features that force read-only mount
1245  * @incompat: bitmask of incompatible features
1246  *
1247  * Mark a given journal feature as present on the
1248  * superblock.  Returns true if the requested features could be set.
1249  *
1250  */
1251
1252 int journal_set_features (journal_t *journal, unsigned long compat,
1253                           unsigned long ro, unsigned long incompat)
1254 {
1255         journal_superblock_t *sb;
1256
1257         if (journal_check_used_features(journal, compat, ro, incompat))
1258                 return 1;
1259
1260         if (!journal_check_available_features(journal, compat, ro, incompat))
1261                 return 0;
1262
1263         jbd_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n",
1264                   compat, ro, incompat);
1265
1266         sb = journal->j_superblock;
1267
1268         sb->s_feature_compat    |= cpu_to_be32(compat);
1269         sb->s_feature_ro_compat |= cpu_to_be32(ro);
1270         sb->s_feature_incompat  |= cpu_to_be32(incompat);
1271
1272         return 1;
1273 }
1274
1275
1276 /**
1277  * int journal_update_format () - Update on-disk journal structure.
1278  * @journal: Journal to act on.
1279  *
1280  * Given an initialised but unloaded journal struct, poke about in the
1281  * on-disk structure to update it to the most recent supported version.
1282  */
1283 int journal_update_format (journal_t *journal)
1284 {
1285         journal_superblock_t *sb;
1286         int err;
1287
1288         err = journal_get_superblock(journal);
1289         if (err)
1290                 return err;
1291
1292         sb = journal->j_superblock;
1293
1294         switch (be32_to_cpu(sb->s_header.h_blocktype)) {
1295         case JFS_SUPERBLOCK_V2:
1296                 return 0;
1297         case JFS_SUPERBLOCK_V1:
1298                 return journal_convert_superblock_v1(journal, sb);
1299         default:
1300                 break;
1301         }
1302         return -EINVAL;
1303 }
1304
1305 static int journal_convert_superblock_v1(journal_t *journal,
1306                                          journal_superblock_t *sb)
1307 {
1308         int offset, blocksize;
1309         struct buffer_head *bh;
1310
1311         printk(KERN_WARNING
1312                 "JBD: Converting superblock from version 1 to 2.\n");
1313
1314         /* Pre-initialise new fields to zero */
1315         offset = ((char *) &(sb->s_feature_compat)) - ((char *) sb);
1316         blocksize = be32_to_cpu(sb->s_blocksize);
1317         memset(&sb->s_feature_compat, 0, blocksize-offset);
1318
1319         sb->s_nr_users = cpu_to_be32(1);
1320         sb->s_header.h_blocktype = cpu_to_be32(JFS_SUPERBLOCK_V2);
1321         journal->j_format_version = 2;
1322
1323         bh = journal->j_sb_buffer;
1324         BUFFER_TRACE(bh, "marking dirty");
1325         mark_buffer_dirty(bh);
1326         sync_dirty_buffer(bh);
1327         return 0;
1328 }
1329
1330
1331 /**
1332  * int journal_flush () - Flush journal
1333  * @journal: Journal to act on.
1334  *
1335  * Flush all data for a given journal to disk and empty the journal.
1336  * Filesystems can use this when remounting readonly to ensure that
1337  * recovery does not need to happen on remount.
1338  */
1339
1340 int journal_flush(journal_t *journal)
1341 {
1342         int err = 0;
1343         transaction_t *transaction = NULL;
1344         unsigned long old_tail;
1345
1346         spin_lock(&journal->j_state_lock);
1347
1348         /* Force everything buffered to the log... */
1349         if (journal->j_running_transaction) {
1350                 transaction = journal->j_running_transaction;
1351                 __log_start_commit(journal, transaction->t_tid);
1352         } else if (journal->j_committing_transaction)
1353                 transaction = journal->j_committing_transaction;
1354
1355         /* Wait for the log commit to complete... */
1356         if (transaction) {
1357                 tid_t tid = transaction->t_tid;
1358
1359                 spin_unlock(&journal->j_state_lock);
1360                 log_wait_commit(journal, tid);
1361         } else {
1362                 spin_unlock(&journal->j_state_lock);
1363         }
1364
1365         /* ...and flush everything in the log out to disk. */
1366         spin_lock(&journal->j_list_lock);
1367         while (!err && journal->j_checkpoint_transactions != NULL) {
1368                 spin_unlock(&journal->j_list_lock);
1369                 err = log_do_checkpoint(journal);
1370                 spin_lock(&journal->j_list_lock);
1371         }
1372         spin_unlock(&journal->j_list_lock);
1373         cleanup_journal_tail(journal);
1374
1375         /* Finally, mark the journal as really needing no recovery.
1376          * This sets s_start==0 in the underlying superblock, which is
1377          * the magic code for a fully-recovered superblock.  Any future
1378          * commits of data to the journal will restore the current
1379          * s_start value. */
1380         spin_lock(&journal->j_state_lock);
1381         old_tail = journal->j_tail;
1382         journal->j_tail = 0;
1383         spin_unlock(&journal->j_state_lock);
1384         journal_update_superblock(journal, 1);
1385         spin_lock(&journal->j_state_lock);
1386         journal->j_tail = old_tail;
1387
1388         J_ASSERT(!journal->j_running_transaction);
1389         J_ASSERT(!journal->j_committing_transaction);
1390         J_ASSERT(!journal->j_checkpoint_transactions);
1391         J_ASSERT(journal->j_head == journal->j_tail);
1392         J_ASSERT(journal->j_tail_sequence == journal->j_transaction_sequence);
1393         spin_unlock(&journal->j_state_lock);
1394         return err;
1395 }
1396
1397 /**
1398  * int journal_wipe() - Wipe journal contents
1399  * @journal: Journal to act on.
1400  * @write: flag (see below)
1401  *
1402  * Wipe out all of the contents of a journal, safely.  This will produce
1403  * a warning if the journal contains any valid recovery information.
1404  * Must be called between journal_init_*() and journal_load().
1405  *
1406  * If 'write' is non-zero, then we wipe out the journal on disk; otherwise
1407  * we merely suppress recovery.
1408  */
1409
1410 int journal_wipe(journal_t *journal, int write)
1411 {
1412         journal_superblock_t *sb;
1413         int err = 0;
1414
1415         J_ASSERT (!(journal->j_flags & JFS_LOADED));
1416
1417         err = load_superblock(journal);
1418         if (err)
1419                 return err;
1420
1421         sb = journal->j_superblock;
1422
1423         if (!journal->j_tail)
1424                 goto no_recovery;
1425
1426         printk (KERN_WARNING "JBD: %s recovery information on journal\n",
1427                 write ? "Clearing" : "Ignoring");
1428
1429         err = journal_skip_recovery(journal);
1430         if (write)
1431                 journal_update_superblock(journal, 1);
1432
1433  no_recovery:
1434         return err;
1435 }
1436
1437 /*
1438  * journal_dev_name: format a character string to describe on what
1439  * device this journal is present.
1440  */
1441
1442 static const char *journal_dev_name(journal_t *journal, char *buffer)
1443 {
1444         struct block_device *bdev;
1445
1446         if (journal->j_inode)
1447                 bdev = journal->j_inode->i_sb->s_bdev;
1448         else
1449                 bdev = journal->j_dev;
1450
1451         return bdevname(bdev, buffer);
1452 }
1453
1454 /*
1455  * Journal abort has very specific semantics, which we describe
1456  * for journal abort.
1457  *
1458  * Two internal function, which provide abort to te jbd layer
1459  * itself are here.
1460  */
1461
1462 /*
1463  * Quick version for internal journal use (doesn't lock the journal).
1464  * Aborts hard --- we mark the abort as occurred, but do _nothing_ else,
1465  * and don't attempt to make any other journal updates.
1466  */
1467 void __journal_abort_hard(journal_t *journal)
1468 {
1469         transaction_t *transaction;
1470         char b[BDEVNAME_SIZE];
1471
1472         if (journal->j_flags & JFS_ABORT)
1473                 return;
1474
1475         printk(KERN_ERR "Aborting journal on device %s.\n",
1476                 journal_dev_name(journal, b));
1477
1478         spin_lock(&journal->j_state_lock);
1479         journal->j_flags |= JFS_ABORT;
1480         transaction = journal->j_running_transaction;
1481         if (transaction)
1482                 __log_start_commit(journal, transaction->t_tid);
1483         spin_unlock(&journal->j_state_lock);
1484 }
1485
1486 /* Soft abort: record the abort error status in the journal superblock,
1487  * but don't do any other IO. */
1488 static void __journal_abort_soft (journal_t *journal, int errno)
1489 {
1490         if (journal->j_flags & JFS_ABORT)
1491                 return;
1492
1493         if (!journal->j_errno)
1494                 journal->j_errno = errno;
1495
1496         __journal_abort_hard(journal);
1497
1498         if (errno)
1499                 journal_update_superblock(journal, 1);
1500 }
1501
1502 /**
1503  * void journal_abort () - Shutdown the journal immediately.
1504  * @journal: the journal to shutdown.
1505  * @errno:   an error number to record in the journal indicating
1506  *           the reason for the shutdown.
1507  *
1508  * Perform a complete, immediate shutdown of the ENTIRE
1509  * journal (not of a single transaction).  This operation cannot be
1510  * undone without closing and reopening the journal.
1511  *
1512  * The journal_abort function is intended to support higher level error
1513  * recovery mechanisms such as the ext2/ext3 remount-readonly error
1514  * mode.
1515  *
1516  * Journal abort has very specific semantics.  Any existing dirty,
1517  * unjournaled buffers in the main filesystem will still be written to
1518  * disk by bdflush, but the journaling mechanism will be suspended
1519  * immediately and no further transaction commits will be honoured.
1520  *
1521  * Any dirty, journaled buffers will be written back to disk without
1522  * hitting the journal.  Atomicity cannot be guaranteed on an aborted
1523  * filesystem, but we _do_ attempt to leave as much data as possible
1524  * behind for fsck to use for cleanup.
1525  *
1526  * Any attempt to get a new transaction handle on a journal which is in
1527  * ABORT state will just result in an -EROFS error return.  A
1528  * journal_stop on an existing handle will return -EIO if we have
1529  * entered abort state during the update.
1530  *
1531  * Recursive transactions are not disturbed by journal abort until the
1532  * final journal_stop, which will receive the -EIO error.
1533  *
1534  * Finally, the journal_abort call allows the caller to supply an errno
1535  * which will be recorded (if possible) in the journal superblock.  This
1536  * allows a client to record failure conditions in the middle of a
1537  * transaction without having to complete the transaction to record the
1538  * failure to disk.  ext3_error, for example, now uses this
1539  * functionality.
1540  *
1541  * Errors which originate from within the journaling layer will NOT
1542  * supply an errno; a null errno implies that absolutely no further
1543  * writes are done to the journal (unless there are any already in
1544  * progress).
1545  *
1546  */
1547
1548 void journal_abort(journal_t *journal, int errno)
1549 {
1550         __journal_abort_soft(journal, errno);
1551 }
1552
1553 /**
1554  * int journal_errno () - returns the journal's error state.
1555  * @journal: journal to examine.
1556  *
1557  * This is the errno numbet set with journal_abort(), the last
1558  * time the journal was mounted - if the journal was stopped
1559  * without calling abort this will be 0.
1560  *
1561  * If the journal has been aborted on this mount time -EROFS will
1562  * be returned.
1563  */
1564 int journal_errno(journal_t *journal)
1565 {
1566         int err;
1567
1568         spin_lock(&journal->j_state_lock);
1569         if (journal->j_flags & JFS_ABORT)
1570                 err = -EROFS;
1571         else
1572                 err = journal->j_errno;
1573         spin_unlock(&journal->j_state_lock);
1574         return err;
1575 }
1576
1577 /**
1578  * int journal_clear_err () - clears the journal's error state
1579  * @journal: journal to act on.
1580  *
1581  * An error must be cleared or Acked to take a FS out of readonly
1582  * mode.
1583  */
1584 int journal_clear_err(journal_t *journal)
1585 {
1586         int err = 0;
1587
1588         spin_lock(&journal->j_state_lock);
1589         if (journal->j_flags & JFS_ABORT)
1590                 err = -EROFS;
1591         else
1592                 journal->j_errno = 0;
1593         spin_unlock(&journal->j_state_lock);
1594         return err;
1595 }
1596
1597 /**
1598  * void journal_ack_err() - Ack journal err.
1599  * @journal: journal to act on.
1600  *
1601  * An error must be cleared or Acked to take a FS out of readonly
1602  * mode.
1603  */
1604 void journal_ack_err(journal_t *journal)
1605 {
1606         spin_lock(&journal->j_state_lock);
1607         if (journal->j_errno)
1608                 journal->j_flags |= JFS_ACK_ERR;
1609         spin_unlock(&journal->j_state_lock);
1610 }
1611
1612 int journal_blocks_per_page(struct inode *inode)
1613 {
1614         return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
1615 }
1616
1617 /*
1618  * Simple support for retrying memory allocations.  Introduced to help to
1619  * debug different VM deadlock avoidance strategies.
1620  */
1621 void * __jbd_kmalloc (const char *where, size_t size, gfp_t flags, int retry)
1622 {
1623         return kmalloc(size, flags | (retry ? __GFP_NOFAIL : 0));
1624 }
1625
1626 /*
1627  * jbd slab management: create 1k, 2k, 4k, 8k slabs as needed
1628  * and allocate frozen and commit buffers from these slabs.
1629  *
1630  * Reason for doing this is to avoid, SLAB_DEBUG - since it could
1631  * cause bh to cross page boundary.
1632  */
1633
1634 #define JBD_MAX_SLABS 5
1635 #define JBD_SLAB_INDEX(size)  (size >> 11)
1636
1637 static struct kmem_cache *jbd_slab[JBD_MAX_SLABS];
1638 static const char *jbd_slab_names[JBD_MAX_SLABS] = {
1639         "jbd_1k", "jbd_2k", "jbd_4k", NULL, "jbd_8k"
1640 };
1641
1642 static void journal_destroy_jbd_slabs(void)
1643 {
1644         int i;
1645
1646         for (i = 0; i < JBD_MAX_SLABS; i++) {
1647                 if (jbd_slab[i])
1648                         kmem_cache_destroy(jbd_slab[i]);
1649                 jbd_slab[i] = NULL;
1650         }
1651 }
1652
1653 static int journal_create_jbd_slab(size_t slab_size)
1654 {
1655         int i = JBD_SLAB_INDEX(slab_size);
1656
1657         BUG_ON(i >= JBD_MAX_SLABS);
1658
1659         /*
1660          * Check if we already have a slab created for this size
1661          */
1662         if (jbd_slab[i])
1663                 return 0;
1664
1665         /*
1666          * Create a slab and force alignment to be same as slabsize -
1667          * this will make sure that allocations won't cross the page
1668          * boundary.
1669          */
1670         jbd_slab[i] = kmem_cache_create(jbd_slab_names[i],
1671                                 slab_size, slab_size, 0, NULL);
1672         if (!jbd_slab[i]) {
1673                 printk(KERN_EMERG "JBD: no memory for jbd_slab cache\n");
1674                 return -ENOMEM;
1675         }
1676         return 0;
1677 }
1678
1679 void * jbd_slab_alloc(size_t size, gfp_t flags)
1680 {
1681         int idx;
1682
1683         idx = JBD_SLAB_INDEX(size);
1684         BUG_ON(jbd_slab[idx] == NULL);
1685         return kmem_cache_alloc(jbd_slab[idx], flags | __GFP_NOFAIL);
1686 }
1687
1688 void jbd_slab_free(void *ptr,  size_t size)
1689 {
1690         int idx;
1691
1692         idx = JBD_SLAB_INDEX(size);
1693         BUG_ON(jbd_slab[idx] == NULL);
1694         kmem_cache_free(jbd_slab[idx], ptr);
1695 }
1696
1697 /*
1698  * Journal_head storage management
1699  */
1700 static struct kmem_cache *journal_head_cache;
1701 #ifdef CONFIG_JBD_DEBUG
1702 static atomic_t nr_journal_heads = ATOMIC_INIT(0);
1703 #endif
1704
1705 static int journal_init_journal_head_cache(void)
1706 {
1707         int retval;
1708
1709         J_ASSERT(journal_head_cache == 0);
1710         journal_head_cache = kmem_cache_create("journal_head",
1711                                 sizeof(struct journal_head),
1712                                 0,              /* offset */
1713                                 0,              /* flags */
1714                                 NULL);          /* ctor */
1715         retval = 0;
1716         if (journal_head_cache == 0) {
1717                 retval = -ENOMEM;
1718                 printk(KERN_EMERG "JBD: no memory for journal_head cache\n");
1719         }
1720         return retval;
1721 }
1722
1723 static void journal_destroy_journal_head_cache(void)
1724 {
1725         J_ASSERT(journal_head_cache != NULL);
1726         kmem_cache_destroy(journal_head_cache);
1727         journal_head_cache = NULL;
1728 }
1729
1730 /*
1731  * journal_head splicing and dicing
1732  */
1733 static struct journal_head *journal_alloc_journal_head(void)
1734 {
1735         struct journal_head *ret;
1736         static unsigned long last_warning;
1737
1738 #ifdef CONFIG_JBD_DEBUG
1739         atomic_inc(&nr_journal_heads);
1740 #endif
1741         ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS);
1742         if (ret == 0) {
1743                 jbd_debug(1, "out of memory for journal_head\n");
1744                 if (time_after(jiffies, last_warning + 5*HZ)) {
1745                         printk(KERN_NOTICE "ENOMEM in %s, retrying.\n",
1746                                __FUNCTION__);
1747                         last_warning = jiffies;
1748                 }
1749                 while (ret == 0) {
1750                         yield();
1751                         ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS);
1752                 }
1753         }
1754         return ret;
1755 }
1756
1757 static void journal_free_journal_head(struct journal_head *jh)
1758 {
1759 #ifdef CONFIG_JBD_DEBUG
1760         atomic_dec(&nr_journal_heads);
1761         memset(jh, JBD_POISON_FREE, sizeof(*jh));
1762 #endif
1763         kmem_cache_free(journal_head_cache, jh);
1764 }
1765
1766 /*
1767  * A journal_head is attached to a buffer_head whenever JBD has an
1768  * interest in the buffer.
1769  *
1770  * Whenever a buffer has an attached journal_head, its ->b_state:BH_JBD bit
1771  * is set.  This bit is tested in core kernel code where we need to take
1772  * JBD-specific actions.  Testing the zeroness of ->b_private is not reliable
1773  * there.
1774  *
1775  * When a buffer has its BH_JBD bit set, its ->b_count is elevated by one.
1776  *
1777  * When a buffer has its BH_JBD bit set it is immune from being released by
1778  * core kernel code, mainly via ->b_count.
1779  *
1780  * A journal_head may be detached from its buffer_head when the journal_head's
1781  * b_transaction, b_cp_transaction and b_next_transaction pointers are NULL.
1782  * Various places in JBD call journal_remove_journal_head() to indicate that the
1783  * journal_head can be dropped if needed.
1784  *
1785  * Various places in the kernel want to attach a journal_head to a buffer_head
1786  * _before_ attaching the journal_head to a transaction.  To protect the
1787  * journal_head in this situation, journal_add_journal_head elevates the
1788  * journal_head's b_jcount refcount by one.  The caller must call
1789  * journal_put_journal_head() to undo this.
1790  *
1791  * So the typical usage would be:
1792  *
1793  *      (Attach a journal_head if needed.  Increments b_jcount)
1794  *      struct journal_head *jh = journal_add_journal_head(bh);
1795  *      ...
1796  *      jh->b_transaction = xxx;
1797  *      journal_put_journal_head(jh);
1798  *
1799  * Now, the journal_head's b_jcount is zero, but it is safe from being released
1800  * because it has a non-zero b_transaction.
1801  */
1802
1803 /*
1804  * Give a buffer_head a journal_head.
1805  *
1806  * Doesn't need the journal lock.
1807  * May sleep.
1808  */
1809 struct journal_head *journal_add_journal_head(struct buffer_head *bh)
1810 {
1811         struct journal_head *jh;
1812         struct journal_head *new_jh = NULL;
1813
1814 repeat:
1815         if (!buffer_jbd(bh)) {
1816                 new_jh = journal_alloc_journal_head();
1817                 memset(new_jh, 0, sizeof(*new_jh));
1818         }
1819
1820         jbd_lock_bh_journal_head(bh);
1821         if (buffer_jbd(bh)) {
1822                 jh = bh2jh(bh);
1823         } else {
1824                 J_ASSERT_BH(bh,
1825                         (atomic_read(&bh->b_count) > 0) ||
1826                         (bh->b_page && bh->b_page->mapping));
1827
1828                 if (!new_jh) {
1829                         jbd_unlock_bh_journal_head(bh);
1830                         goto repeat;
1831                 }
1832
1833                 jh = new_jh;
1834                 new_jh = NULL;          /* We consumed it */
1835                 set_buffer_jbd(bh);
1836                 bh->b_private = jh;
1837                 jh->b_bh = bh;
1838                 get_bh(bh);
1839                 BUFFER_TRACE(bh, "added journal_head");
1840         }
1841         jh->b_jcount++;
1842         jbd_unlock_bh_journal_head(bh);
1843         if (new_jh)
1844                 journal_free_journal_head(new_jh);
1845         return bh->b_private;
1846 }
1847
1848 /*
1849  * Grab a ref against this buffer_head's journal_head.  If it ended up not
1850  * having a journal_head, return NULL
1851  */
1852 struct journal_head *journal_grab_journal_head(struct buffer_head *bh)
1853 {
1854         struct journal_head *jh = NULL;
1855
1856         jbd_lock_bh_journal_head(bh);
1857         if (buffer_jbd(bh)) {
1858                 jh = bh2jh(bh);
1859                 jh->b_jcount++;
1860         }
1861         jbd_unlock_bh_journal_head(bh);
1862         return jh;
1863 }
1864
1865 static void __journal_remove_journal_head(struct buffer_head *bh)
1866 {
1867         struct journal_head *jh = bh2jh(bh);
1868
1869         J_ASSERT_JH(jh, jh->b_jcount >= 0);
1870
1871         get_bh(bh);
1872         if (jh->b_jcount == 0) {
1873                 if (jh->b_transaction == NULL &&
1874                                 jh->b_next_transaction == NULL &&
1875                                 jh->b_cp_transaction == NULL) {
1876                         J_ASSERT_JH(jh, jh->b_jlist == BJ_None);
1877                         J_ASSERT_BH(bh, buffer_jbd(bh));
1878                         J_ASSERT_BH(bh, jh2bh(jh) == bh);
1879                         BUFFER_TRACE(bh, "remove journal_head");
1880                         if (jh->b_frozen_data) {
1881                                 printk(KERN_WARNING "%s: freeing "
1882                                                 "b_frozen_data\n",
1883                                                 __FUNCTION__);
1884                                 jbd_slab_free(jh->b_frozen_data, bh->b_size);
1885                         }
1886                         if (jh->b_committed_data) {
1887                                 printk(KERN_WARNING "%s: freeing "
1888                                                 "b_committed_data\n",
1889                                                 __FUNCTION__);
1890                                 jbd_slab_free(jh->b_committed_data, bh->b_size);
1891                         }
1892                         bh->b_private = NULL;
1893                         jh->b_bh = NULL;        /* debug, really */
1894                         clear_buffer_jbd(bh);
1895                         __brelse(bh);
1896                         journal_free_journal_head(jh);
1897                 } else {
1898                         BUFFER_TRACE(bh, "journal_head was locked");
1899                 }
1900         }
1901 }
1902
1903 /*
1904  * journal_remove_journal_head(): if the buffer isn't attached to a transaction
1905  * and has a zero b_jcount then remove and release its journal_head.   If we did
1906  * see that the buffer is not used by any transaction we also "logically"
1907  * decrement ->b_count.
1908  *
1909  * We in fact take an additional increment on ->b_count as a convenience,
1910  * because the caller usually wants to do additional things with the bh
1911  * after calling here.
1912  * The caller of journal_remove_journal_head() *must* run __brelse(bh) at some
1913  * time.  Once the caller has run __brelse(), the buffer is eligible for
1914  * reaping by try_to_free_buffers().
1915  */
1916 void journal_remove_journal_head(struct buffer_head *bh)
1917 {
1918         jbd_lock_bh_journal_head(bh);
1919         __journal_remove_journal_head(bh);
1920         jbd_unlock_bh_journal_head(bh);
1921 }
1922
1923 /*
1924  * Drop a reference on the passed journal_head.  If it fell to zero then try to
1925  * release the journal_head from the buffer_head.
1926  */
1927 void journal_put_journal_head(struct journal_head *jh)
1928 {
1929         struct buffer_head *bh = jh2bh(jh);
1930
1931         jbd_lock_bh_journal_head(bh);
1932         J_ASSERT_JH(jh, jh->b_jcount > 0);
1933         --jh->b_jcount;
1934         if (!jh->b_jcount && !jh->b_transaction) {
1935                 __journal_remove_journal_head(bh);
1936                 __brelse(bh);
1937         }
1938         jbd_unlock_bh_journal_head(bh);
1939 }
1940
1941 /*
1942  * /proc tunables
1943  */
1944 #if defined(CONFIG_JBD_DEBUG)
1945 int journal_enable_debug;
1946 EXPORT_SYMBOL(journal_enable_debug);
1947 #endif
1948
1949 #if defined(CONFIG_JBD_DEBUG) && defined(CONFIG_PROC_FS)
1950
1951 static struct proc_dir_entry *proc_jbd_debug;
1952
1953 static int read_jbd_debug(char *page, char **start, off_t off,
1954                           int count, int *eof, void *data)
1955 {
1956         int ret;
1957
1958         ret = sprintf(page + off, "%d\n", journal_enable_debug);
1959         *eof = 1;
1960         return ret;
1961 }
1962
1963 static int write_jbd_debug(struct file *file, const char __user *buffer,
1964                            unsigned long count, void *data)
1965 {
1966         char buf[32];
1967
1968         if (count > ARRAY_SIZE(buf) - 1)
1969                 count = ARRAY_SIZE(buf) - 1;
1970         if (copy_from_user(buf, buffer, count))
1971                 return -EFAULT;
1972         buf[ARRAY_SIZE(buf) - 1] = '\0';
1973         journal_enable_debug = simple_strtoul(buf, NULL, 10);
1974         return count;
1975 }
1976
1977 #define JBD_PROC_NAME "sys/fs/jbd-debug"
1978
1979 static void __init create_jbd_proc_entry(void)
1980 {
1981         proc_jbd_debug = create_proc_entry(JBD_PROC_NAME, 0644, NULL);
1982         if (proc_jbd_debug) {
1983                 /* Why is this so hard? */
1984                 proc_jbd_debug->read_proc = read_jbd_debug;
1985                 proc_jbd_debug->write_proc = write_jbd_debug;
1986         }
1987 }
1988
1989 static void __exit remove_jbd_proc_entry(void)
1990 {
1991         if (proc_jbd_debug)
1992                 remove_proc_entry(JBD_PROC_NAME, NULL);
1993 }
1994
1995 #else
1996
1997 #define create_jbd_proc_entry() do {} while (0)
1998 #define remove_jbd_proc_entry() do {} while (0)
1999
2000 #endif
2001
2002 struct kmem_cache *jbd_handle_cache;
2003
2004 static int __init journal_init_handle_cache(void)
2005 {
2006         jbd_handle_cache = kmem_cache_create("journal_handle",
2007                                 sizeof(handle_t),
2008                                 0,              /* offset */
2009                                 0,              /* flags */
2010                                 NULL);          /* ctor */
2011         if (jbd_handle_cache == NULL) {
2012                 printk(KERN_EMERG "JBD: failed to create handle cache\n");
2013                 return -ENOMEM;
2014         }
2015         return 0;
2016 }
2017
2018 static void journal_destroy_handle_cache(void)
2019 {
2020         if (jbd_handle_cache)
2021                 kmem_cache_destroy(jbd_handle_cache);
2022 }
2023
2024 /*
2025  * Module startup and shutdown
2026  */
2027
2028 static int __init journal_init_caches(void)
2029 {
2030         int ret;
2031
2032         ret = journal_init_revoke_caches();
2033         if (ret == 0)
2034                 ret = journal_init_journal_head_cache();
2035         if (ret == 0)
2036                 ret = journal_init_handle_cache();
2037         return ret;
2038 }
2039
2040 static void journal_destroy_caches(void)
2041 {
2042         journal_destroy_revoke_caches();
2043         journal_destroy_journal_head_cache();
2044         journal_destroy_handle_cache();
2045         journal_destroy_jbd_slabs();
2046 }
2047
2048 static int __init journal_init(void)
2049 {
2050         int ret;
2051
2052         BUILD_BUG_ON(sizeof(struct journal_superblock_s) != 1024);
2053
2054         ret = journal_init_caches();
2055         if (ret != 0)
2056                 journal_destroy_caches();
2057         create_jbd_proc_entry();
2058         return ret;
2059 }
2060
2061 static void __exit journal_exit(void)
2062 {
2063 #ifdef CONFIG_JBD_DEBUG
2064         int n = atomic_read(&nr_journal_heads);
2065         if (n)
2066                 printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n);
2067 #endif
2068         remove_jbd_proc_entry();
2069         journal_destroy_caches();
2070 }
2071
2072 MODULE_LICENSE("GPL");
2073 module_init(journal_init);
2074 module_exit(journal_exit);
2075