[PATCH] slab: remove kmem_cache_t
[linux-3.10.git] / fs / jbd2 / journal.c
1 /*
2  * linux/fs/jbd2/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/jbd2.h>
29 #include <linux/errno.h>
30 #include <linux/slab.h>
31 #include <linux/smp_lock.h>
32 #include <linux/init.h>
33 #include <linux/mm.h>
34 #include <linux/suspend.h>
35 #include <linux/pagemap.h>
36 #include <linux/kthread.h>
37 #include <linux/poison.h>
38 #include <linux/proc_fs.h>
39
40 #include <asm/uaccess.h>
41 #include <asm/page.h>
42
43 EXPORT_SYMBOL(jbd2_journal_start);
44 EXPORT_SYMBOL(jbd2_journal_restart);
45 EXPORT_SYMBOL(jbd2_journal_extend);
46 EXPORT_SYMBOL(jbd2_journal_stop);
47 EXPORT_SYMBOL(jbd2_journal_lock_updates);
48 EXPORT_SYMBOL(jbd2_journal_unlock_updates);
49 EXPORT_SYMBOL(jbd2_journal_get_write_access);
50 EXPORT_SYMBOL(jbd2_journal_get_create_access);
51 EXPORT_SYMBOL(jbd2_journal_get_undo_access);
52 EXPORT_SYMBOL(jbd2_journal_dirty_data);
53 EXPORT_SYMBOL(jbd2_journal_dirty_metadata);
54 EXPORT_SYMBOL(jbd2_journal_release_buffer);
55 EXPORT_SYMBOL(jbd2_journal_forget);
56 #if 0
57 EXPORT_SYMBOL(journal_sync_buffer);
58 #endif
59 EXPORT_SYMBOL(jbd2_journal_flush);
60 EXPORT_SYMBOL(jbd2_journal_revoke);
61
62 EXPORT_SYMBOL(jbd2_journal_init_dev);
63 EXPORT_SYMBOL(jbd2_journal_init_inode);
64 EXPORT_SYMBOL(jbd2_journal_update_format);
65 EXPORT_SYMBOL(jbd2_journal_check_used_features);
66 EXPORT_SYMBOL(jbd2_journal_check_available_features);
67 EXPORT_SYMBOL(jbd2_journal_set_features);
68 EXPORT_SYMBOL(jbd2_journal_create);
69 EXPORT_SYMBOL(jbd2_journal_load);
70 EXPORT_SYMBOL(jbd2_journal_destroy);
71 EXPORT_SYMBOL(jbd2_journal_update_superblock);
72 EXPORT_SYMBOL(jbd2_journal_abort);
73 EXPORT_SYMBOL(jbd2_journal_errno);
74 EXPORT_SYMBOL(jbd2_journal_ack_err);
75 EXPORT_SYMBOL(jbd2_journal_clear_err);
76 EXPORT_SYMBOL(jbd2_log_wait_commit);
77 EXPORT_SYMBOL(jbd2_journal_start_commit);
78 EXPORT_SYMBOL(jbd2_journal_force_commit_nested);
79 EXPORT_SYMBOL(jbd2_journal_wipe);
80 EXPORT_SYMBOL(jbd2_journal_blocks_per_page);
81 EXPORT_SYMBOL(jbd2_journal_invalidatepage);
82 EXPORT_SYMBOL(jbd2_journal_try_to_free_buffers);
83 EXPORT_SYMBOL(jbd2_journal_force_commit);
84
85 static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *);
86 static void __journal_abort_soft (journal_t *journal, int errno);
87 static int jbd2_journal_create_jbd_slab(size_t slab_size);
88
89 /*
90  * Helper function used to manage commit timeouts
91  */
92
93 static void commit_timeout(unsigned long __data)
94 {
95         struct task_struct * p = (struct task_struct *) __data;
96
97         wake_up_process(p);
98 }
99
100 /*
101  * kjournald2: The main thread function used to manage a logging device
102  * journal.
103  *
104  * This kernel thread is responsible for two things:
105  *
106  * 1) COMMIT:  Every so often we need to commit the current state of the
107  *    filesystem to disk.  The journal thread is responsible for writing
108  *    all of the metadata buffers to disk.
109  *
110  * 2) CHECKPOINT: We cannot reuse a used section of the log file until all
111  *    of the data in that part of the log has been rewritten elsewhere on
112  *    the disk.  Flushing these old buffers to reclaim space in the log is
113  *    known as checkpointing, and this thread is responsible for that job.
114  */
115
116 static int kjournald2(void *arg)
117 {
118         journal_t *journal = arg;
119         transaction_t *transaction;
120
121         /*
122          * Set up an interval timer which can be used to trigger a commit wakeup
123          * after the commit interval expires
124          */
125         setup_timer(&journal->j_commit_timer, commit_timeout,
126                         (unsigned long)current);
127
128         /* Record that the journal thread is running */
129         journal->j_task = current;
130         wake_up(&journal->j_wait_done_commit);
131
132         printk(KERN_INFO "kjournald2 starting.  Commit interval %ld seconds\n",
133                         journal->j_commit_interval / HZ);
134
135         /*
136          * And now, wait forever for commit wakeup events.
137          */
138         spin_lock(&journal->j_state_lock);
139
140 loop:
141         if (journal->j_flags & JBD2_UNMOUNT)
142                 goto end_loop;
143
144         jbd_debug(1, "commit_sequence=%d, commit_request=%d\n",
145                 journal->j_commit_sequence, journal->j_commit_request);
146
147         if (journal->j_commit_sequence != journal->j_commit_request) {
148                 jbd_debug(1, "OK, requests differ\n");
149                 spin_unlock(&journal->j_state_lock);
150                 del_timer_sync(&journal->j_commit_timer);
151                 jbd2_journal_commit_transaction(journal);
152                 spin_lock(&journal->j_state_lock);
153                 goto loop;
154         }
155
156         wake_up(&journal->j_wait_done_commit);
157         if (freezing(current)) {
158                 /*
159                  * The simpler the better. Flushing journal isn't a
160                  * good idea, because that depends on threads that may
161                  * be already stopped.
162                  */
163                 jbd_debug(1, "Now suspending kjournald2\n");
164                 spin_unlock(&journal->j_state_lock);
165                 refrigerator();
166                 spin_lock(&journal->j_state_lock);
167         } else {
168                 /*
169                  * We assume on resume that commits are already there,
170                  * so we don't sleep
171                  */
172                 DEFINE_WAIT(wait);
173                 int should_sleep = 1;
174
175                 prepare_to_wait(&journal->j_wait_commit, &wait,
176                                 TASK_INTERRUPTIBLE);
177                 if (journal->j_commit_sequence != journal->j_commit_request)
178                         should_sleep = 0;
179                 transaction = journal->j_running_transaction;
180                 if (transaction && time_after_eq(jiffies,
181                                                 transaction->t_expires))
182                         should_sleep = 0;
183                 if (journal->j_flags & JBD2_UNMOUNT)
184                         should_sleep = 0;
185                 if (should_sleep) {
186                         spin_unlock(&journal->j_state_lock);
187                         schedule();
188                         spin_lock(&journal->j_state_lock);
189                 }
190                 finish_wait(&journal->j_wait_commit, &wait);
191         }
192
193         jbd_debug(1, "kjournald2 wakes\n");
194
195         /*
196          * Were we woken up by a commit wakeup event?
197          */
198         transaction = journal->j_running_transaction;
199         if (transaction && time_after_eq(jiffies, transaction->t_expires)) {
200                 journal->j_commit_request = transaction->t_tid;
201                 jbd_debug(1, "woke because of timeout\n");
202         }
203         goto loop;
204
205 end_loop:
206         spin_unlock(&journal->j_state_lock);
207         del_timer_sync(&journal->j_commit_timer);
208         journal->j_task = NULL;
209         wake_up(&journal->j_wait_done_commit);
210         jbd_debug(1, "Journal thread exiting.\n");
211         return 0;
212 }
213
214 static void jbd2_journal_start_thread(journal_t *journal)
215 {
216         kthread_run(kjournald2, journal, "kjournald2");
217         wait_event(journal->j_wait_done_commit, journal->j_task != 0);
218 }
219
220 static void journal_kill_thread(journal_t *journal)
221 {
222         spin_lock(&journal->j_state_lock);
223         journal->j_flags |= JBD2_UNMOUNT;
224
225         while (journal->j_task) {
226                 wake_up(&journal->j_wait_commit);
227                 spin_unlock(&journal->j_state_lock);
228                 wait_event(journal->j_wait_done_commit, journal->j_task == 0);
229                 spin_lock(&journal->j_state_lock);
230         }
231         spin_unlock(&journal->j_state_lock);
232 }
233
234 /*
235  * jbd2_journal_write_metadata_buffer: write a metadata buffer to the journal.
236  *
237  * Writes a metadata buffer to a given disk block.  The actual IO is not
238  * performed but a new buffer_head is constructed which labels the data
239  * to be written with the correct destination disk block.
240  *
241  * Any magic-number escaping which needs to be done will cause a
242  * copy-out here.  If the buffer happens to start with the
243  * JBD2_MAGIC_NUMBER, then we can't write it to the log directly: the
244  * magic number is only written to the log for descripter blocks.  In
245  * this case, we copy the data and replace the first word with 0, and we
246  * return a result code which indicates that this buffer needs to be
247  * marked as an escaped buffer in the corresponding log descriptor
248  * block.  The missing word can then be restored when the block is read
249  * during recovery.
250  *
251  * If the source buffer has already been modified by a new transaction
252  * since we took the last commit snapshot, we use the frozen copy of
253  * that data for IO.  If we end up using the existing buffer_head's data
254  * for the write, then we *have* to lock the buffer to prevent anyone
255  * else from using and possibly modifying it while the IO is in
256  * progress.
257  *
258  * The function returns a pointer to the buffer_heads to be used for IO.
259  *
260  * We assume that the journal has already been locked in this function.
261  *
262  * Return value:
263  *  <0: Error
264  * >=0: Finished OK
265  *
266  * On success:
267  * Bit 0 set == escape performed on the data
268  * Bit 1 set == buffer copy-out performed (kfree the data after IO)
269  */
270
271 int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
272                                   struct journal_head  *jh_in,
273                                   struct journal_head **jh_out,
274                                   unsigned long long blocknr)
275 {
276         int need_copy_out = 0;
277         int done_copy_out = 0;
278         int do_escape = 0;
279         char *mapped_data;
280         struct buffer_head *new_bh;
281         struct journal_head *new_jh;
282         struct page *new_page;
283         unsigned int new_offset;
284         struct buffer_head *bh_in = jh2bh(jh_in);
285
286         /*
287          * The buffer really shouldn't be locked: only the current committing
288          * transaction is allowed to write it, so nobody else is allowed
289          * to do any IO.
290          *
291          * akpm: except if we're journalling data, and write() output is
292          * also part of a shared mapping, and another thread has
293          * decided to launch a writepage() against this buffer.
294          */
295         J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in));
296
297         new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL);
298
299         /*
300          * If a new transaction has already done a buffer copy-out, then
301          * we use that version of the data for the commit.
302          */
303         jbd_lock_bh_state(bh_in);
304 repeat:
305         if (jh_in->b_frozen_data) {
306                 done_copy_out = 1;
307                 new_page = virt_to_page(jh_in->b_frozen_data);
308                 new_offset = offset_in_page(jh_in->b_frozen_data);
309         } else {
310                 new_page = jh2bh(jh_in)->b_page;
311                 new_offset = offset_in_page(jh2bh(jh_in)->b_data);
312         }
313
314         mapped_data = kmap_atomic(new_page, KM_USER0);
315         /*
316          * Check for escaping
317          */
318         if (*((__be32 *)(mapped_data + new_offset)) ==
319                                 cpu_to_be32(JBD2_MAGIC_NUMBER)) {
320                 need_copy_out = 1;
321                 do_escape = 1;
322         }
323         kunmap_atomic(mapped_data, KM_USER0);
324
325         /*
326          * Do we need to do a data copy?
327          */
328         if (need_copy_out && !done_copy_out) {
329                 char *tmp;
330
331                 jbd_unlock_bh_state(bh_in);
332                 tmp = jbd2_slab_alloc(bh_in->b_size, GFP_NOFS);
333                 jbd_lock_bh_state(bh_in);
334                 if (jh_in->b_frozen_data) {
335                         jbd2_slab_free(tmp, bh_in->b_size);
336                         goto repeat;
337                 }
338
339                 jh_in->b_frozen_data = tmp;
340                 mapped_data = kmap_atomic(new_page, KM_USER0);
341                 memcpy(tmp, mapped_data + new_offset, jh2bh(jh_in)->b_size);
342                 kunmap_atomic(mapped_data, KM_USER0);
343
344                 new_page = virt_to_page(tmp);
345                 new_offset = offset_in_page(tmp);
346                 done_copy_out = 1;
347         }
348
349         /*
350          * Did we need to do an escaping?  Now we've done all the
351          * copying, we can finally do so.
352          */
353         if (do_escape) {
354                 mapped_data = kmap_atomic(new_page, KM_USER0);
355                 *((unsigned int *)(mapped_data + new_offset)) = 0;
356                 kunmap_atomic(mapped_data, KM_USER0);
357         }
358
359         /* keep subsequent assertions sane */
360         new_bh->b_state = 0;
361         init_buffer(new_bh, NULL, NULL);
362         atomic_set(&new_bh->b_count, 1);
363         jbd_unlock_bh_state(bh_in);
364
365         new_jh = jbd2_journal_add_journal_head(new_bh); /* This sleeps */
366
367         set_bh_page(new_bh, new_page, new_offset);
368         new_jh->b_transaction = NULL;
369         new_bh->b_size = jh2bh(jh_in)->b_size;
370         new_bh->b_bdev = transaction->t_journal->j_dev;
371         new_bh->b_blocknr = blocknr;
372         set_buffer_mapped(new_bh);
373         set_buffer_dirty(new_bh);
374
375         *jh_out = new_jh;
376
377         /*
378          * The to-be-written buffer needs to get moved to the io queue,
379          * and the original buffer whose contents we are shadowing or
380          * copying is moved to the transaction's shadow queue.
381          */
382         JBUFFER_TRACE(jh_in, "file as BJ_Shadow");
383         jbd2_journal_file_buffer(jh_in, transaction, BJ_Shadow);
384         JBUFFER_TRACE(new_jh, "file as BJ_IO");
385         jbd2_journal_file_buffer(new_jh, transaction, BJ_IO);
386
387         return do_escape | (done_copy_out << 1);
388 }
389
390 /*
391  * Allocation code for the journal file.  Manage the space left in the
392  * journal, so that we can begin checkpointing when appropriate.
393  */
394
395 /*
396  * __jbd2_log_space_left: Return the number of free blocks left in the journal.
397  *
398  * Called with the journal already locked.
399  *
400  * Called under j_state_lock
401  */
402
403 int __jbd2_log_space_left(journal_t *journal)
404 {
405         int left = journal->j_free;
406
407         assert_spin_locked(&journal->j_state_lock);
408
409         /*
410          * Be pessimistic here about the number of those free blocks which
411          * might be required for log descriptor control blocks.
412          */
413
414 #define MIN_LOG_RESERVED_BLOCKS 32 /* Allow for rounding errors */
415
416         left -= MIN_LOG_RESERVED_BLOCKS;
417
418         if (left <= 0)
419                 return 0;
420         left -= (left >> 3);
421         return left;
422 }
423
424 /*
425  * Called under j_state_lock.  Returns true if a transaction was started.
426  */
427 int __jbd2_log_start_commit(journal_t *journal, tid_t target)
428 {
429         /*
430          * Are we already doing a recent enough commit?
431          */
432         if (!tid_geq(journal->j_commit_request, target)) {
433                 /*
434                  * We want a new commit: OK, mark the request and wakup the
435                  * commit thread.  We do _not_ do the commit ourselves.
436                  */
437
438                 journal->j_commit_request = target;
439                 jbd_debug(1, "JBD: requesting commit %d/%d\n",
440                           journal->j_commit_request,
441                           journal->j_commit_sequence);
442                 wake_up(&journal->j_wait_commit);
443                 return 1;
444         }
445         return 0;
446 }
447
448 int jbd2_log_start_commit(journal_t *journal, tid_t tid)
449 {
450         int ret;
451
452         spin_lock(&journal->j_state_lock);
453         ret = __jbd2_log_start_commit(journal, tid);
454         spin_unlock(&journal->j_state_lock);
455         return ret;
456 }
457
458 /*
459  * Force and wait upon a commit if the calling process is not within
460  * transaction.  This is used for forcing out undo-protected data which contains
461  * bitmaps, when the fs is running out of space.
462  *
463  * We can only force the running transaction if we don't have an active handle;
464  * otherwise, we will deadlock.
465  *
466  * Returns true if a transaction was started.
467  */
468 int jbd2_journal_force_commit_nested(journal_t *journal)
469 {
470         transaction_t *transaction = NULL;
471         tid_t tid;
472
473         spin_lock(&journal->j_state_lock);
474         if (journal->j_running_transaction && !current->journal_info) {
475                 transaction = journal->j_running_transaction;
476                 __jbd2_log_start_commit(journal, transaction->t_tid);
477         } else if (journal->j_committing_transaction)
478                 transaction = journal->j_committing_transaction;
479
480         if (!transaction) {
481                 spin_unlock(&journal->j_state_lock);
482                 return 0;       /* Nothing to retry */
483         }
484
485         tid = transaction->t_tid;
486         spin_unlock(&journal->j_state_lock);
487         jbd2_log_wait_commit(journal, tid);
488         return 1;
489 }
490
491 /*
492  * Start a commit of the current running transaction (if any).  Returns true
493  * if a transaction was started, and fills its tid in at *ptid
494  */
495 int jbd2_journal_start_commit(journal_t *journal, tid_t *ptid)
496 {
497         int ret = 0;
498
499         spin_lock(&journal->j_state_lock);
500         if (journal->j_running_transaction) {
501                 tid_t tid = journal->j_running_transaction->t_tid;
502
503                 ret = __jbd2_log_start_commit(journal, tid);
504                 if (ret && ptid)
505                         *ptid = tid;
506         } else if (journal->j_committing_transaction && ptid) {
507                 /*
508                  * If ext3_write_super() recently started a commit, then we
509                  * have to wait for completion of that transaction
510                  */
511                 *ptid = journal->j_committing_transaction->t_tid;
512                 ret = 1;
513         }
514         spin_unlock(&journal->j_state_lock);
515         return ret;
516 }
517
518 /*
519  * Wait for a specified commit to complete.
520  * The caller may not hold the journal lock.
521  */
522 int jbd2_log_wait_commit(journal_t *journal, tid_t tid)
523 {
524         int err = 0;
525
526 #ifdef CONFIG_JBD_DEBUG
527         spin_lock(&journal->j_state_lock);
528         if (!tid_geq(journal->j_commit_request, tid)) {
529                 printk(KERN_EMERG
530                        "%s: error: j_commit_request=%d, tid=%d\n",
531                        __FUNCTION__, journal->j_commit_request, tid);
532         }
533         spin_unlock(&journal->j_state_lock);
534 #endif
535         spin_lock(&journal->j_state_lock);
536         while (tid_gt(tid, journal->j_commit_sequence)) {
537                 jbd_debug(1, "JBD: want %d, j_commit_sequence=%d\n",
538                                   tid, journal->j_commit_sequence);
539                 wake_up(&journal->j_wait_commit);
540                 spin_unlock(&journal->j_state_lock);
541                 wait_event(journal->j_wait_done_commit,
542                                 !tid_gt(tid, journal->j_commit_sequence));
543                 spin_lock(&journal->j_state_lock);
544         }
545         spin_unlock(&journal->j_state_lock);
546
547         if (unlikely(is_journal_aborted(journal))) {
548                 printk(KERN_EMERG "journal commit I/O error\n");
549                 err = -EIO;
550         }
551         return err;
552 }
553
554 /*
555  * Log buffer allocation routines:
556  */
557
558 int jbd2_journal_next_log_block(journal_t *journal, unsigned long long *retp)
559 {
560         unsigned long blocknr;
561
562         spin_lock(&journal->j_state_lock);
563         J_ASSERT(journal->j_free > 1);
564
565         blocknr = journal->j_head;
566         journal->j_head++;
567         journal->j_free--;
568         if (journal->j_head == journal->j_last)
569                 journal->j_head = journal->j_first;
570         spin_unlock(&journal->j_state_lock);
571         return jbd2_journal_bmap(journal, blocknr, retp);
572 }
573
574 /*
575  * Conversion of logical to physical block numbers for the journal
576  *
577  * On external journals the journal blocks are identity-mapped, so
578  * this is a no-op.  If needed, we can use j_blk_offset - everything is
579  * ready.
580  */
581 int jbd2_journal_bmap(journal_t *journal, unsigned long blocknr,
582                  unsigned long long *retp)
583 {
584         int err = 0;
585         unsigned long long ret;
586
587         if (journal->j_inode) {
588                 ret = bmap(journal->j_inode, blocknr);
589                 if (ret)
590                         *retp = ret;
591                 else {
592                         char b[BDEVNAME_SIZE];
593
594                         printk(KERN_ALERT "%s: journal block not found "
595                                         "at offset %lu on %s\n",
596                                 __FUNCTION__,
597                                 blocknr,
598                                 bdevname(journal->j_dev, b));
599                         err = -EIO;
600                         __journal_abort_soft(journal, err);
601                 }
602         } else {
603                 *retp = blocknr; /* +journal->j_blk_offset */
604         }
605         return err;
606 }
607
608 /*
609  * We play buffer_head aliasing tricks to write data/metadata blocks to
610  * the journal without copying their contents, but for journal
611  * descriptor blocks we do need to generate bona fide buffers.
612  *
613  * After the caller of jbd2_journal_get_descriptor_buffer() has finished modifying
614  * the buffer's contents they really should run flush_dcache_page(bh->b_page).
615  * But we don't bother doing that, so there will be coherency problems with
616  * mmaps of blockdevs which hold live JBD-controlled filesystems.
617  */
618 struct journal_head *jbd2_journal_get_descriptor_buffer(journal_t *journal)
619 {
620         struct buffer_head *bh;
621         unsigned long long blocknr;
622         int err;
623
624         err = jbd2_journal_next_log_block(journal, &blocknr);
625
626         if (err)
627                 return NULL;
628
629         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
630         lock_buffer(bh);
631         memset(bh->b_data, 0, journal->j_blocksize);
632         set_buffer_uptodate(bh);
633         unlock_buffer(bh);
634         BUFFER_TRACE(bh, "return this buffer");
635         return jbd2_journal_add_journal_head(bh);
636 }
637
638 /*
639  * Management for journal control blocks: functions to create and
640  * destroy journal_t structures, and to initialise and read existing
641  * journal blocks from disk.  */
642
643 /* First: create and setup a journal_t object in memory.  We initialise
644  * very few fields yet: that has to wait until we have created the
645  * journal structures from from scratch, or loaded them from disk. */
646
647 static journal_t * journal_init_common (void)
648 {
649         journal_t *journal;
650         int err;
651
652         journal = jbd_kmalloc(sizeof(*journal), GFP_KERNEL);
653         if (!journal)
654                 goto fail;
655         memset(journal, 0, sizeof(*journal));
656
657         init_waitqueue_head(&journal->j_wait_transaction_locked);
658         init_waitqueue_head(&journal->j_wait_logspace);
659         init_waitqueue_head(&journal->j_wait_done_commit);
660         init_waitqueue_head(&journal->j_wait_checkpoint);
661         init_waitqueue_head(&journal->j_wait_commit);
662         init_waitqueue_head(&journal->j_wait_updates);
663         mutex_init(&journal->j_barrier);
664         mutex_init(&journal->j_checkpoint_mutex);
665         spin_lock_init(&journal->j_revoke_lock);
666         spin_lock_init(&journal->j_list_lock);
667         spin_lock_init(&journal->j_state_lock);
668
669         journal->j_commit_interval = (HZ * JBD_DEFAULT_MAX_COMMIT_AGE);
670
671         /* The journal is marked for error until we succeed with recovery! */
672         journal->j_flags = JBD2_ABORT;
673
674         /* Set up a default-sized revoke table for the new mount. */
675         err = jbd2_journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH);
676         if (err) {
677                 kfree(journal);
678                 goto fail;
679         }
680         return journal;
681 fail:
682         return NULL;
683 }
684
685 /* jbd2_journal_init_dev and jbd2_journal_init_inode:
686  *
687  * Create a journal structure assigned some fixed set of disk blocks to
688  * the journal.  We don't actually touch those disk blocks yet, but we
689  * need to set up all of the mapping information to tell the journaling
690  * system where the journal blocks are.
691  *
692  */
693
694 /**
695  *  journal_t * jbd2_journal_init_dev() - creates an initialises a journal structure
696  *  @bdev: Block device on which to create the journal
697  *  @fs_dev: Device which hold journalled filesystem for this journal.
698  *  @start: Block nr Start of journal.
699  *  @len:  Length of the journal in blocks.
700  *  @blocksize: blocksize of journalling device
701  *  @returns: a newly created journal_t *
702  *
703  *  jbd2_journal_init_dev creates a journal which maps a fixed contiguous
704  *  range of blocks on an arbitrary block device.
705  *
706  */
707 journal_t * jbd2_journal_init_dev(struct block_device *bdev,
708                         struct block_device *fs_dev,
709                         unsigned long long start, int len, int blocksize)
710 {
711         journal_t *journal = journal_init_common();
712         struct buffer_head *bh;
713         int n;
714
715         if (!journal)
716                 return NULL;
717
718         /* journal descriptor can store up to n blocks -bzzz */
719         journal->j_blocksize = blocksize;
720         n = journal->j_blocksize / sizeof(journal_block_tag_t);
721         journal->j_wbufsize = n;
722         journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
723         if (!journal->j_wbuf) {
724                 printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
725                         __FUNCTION__);
726                 kfree(journal);
727                 journal = NULL;
728                 goto out;
729         }
730         journal->j_dev = bdev;
731         journal->j_fs_dev = fs_dev;
732         journal->j_blk_offset = start;
733         journal->j_maxlen = len;
734
735         bh = __getblk(journal->j_dev, start, journal->j_blocksize);
736         J_ASSERT(bh != NULL);
737         journal->j_sb_buffer = bh;
738         journal->j_superblock = (journal_superblock_t *)bh->b_data;
739 out:
740         return journal;
741 }
742
743 /**
744  *  journal_t * jbd2_journal_init_inode () - creates a journal which maps to a inode.
745  *  @inode: An inode to create the journal in
746  *
747  * jbd2_journal_init_inode creates a journal which maps an on-disk inode as
748  * the journal.  The inode must exist already, must support bmap() and
749  * must have all data blocks preallocated.
750  */
751 journal_t * jbd2_journal_init_inode (struct inode *inode)
752 {
753         struct buffer_head *bh;
754         journal_t *journal = journal_init_common();
755         int err;
756         int n;
757         unsigned long long blocknr;
758
759         if (!journal)
760                 return NULL;
761
762         journal->j_dev = journal->j_fs_dev = inode->i_sb->s_bdev;
763         journal->j_inode = inode;
764         jbd_debug(1,
765                   "journal %p: inode %s/%ld, size %Ld, bits %d, blksize %ld\n",
766                   journal, inode->i_sb->s_id, inode->i_ino,
767                   (long long) inode->i_size,
768                   inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize);
769
770         journal->j_maxlen = inode->i_size >> inode->i_sb->s_blocksize_bits;
771         journal->j_blocksize = inode->i_sb->s_blocksize;
772
773         /* journal descriptor can store up to n blocks -bzzz */
774         n = journal->j_blocksize / sizeof(journal_block_tag_t);
775         journal->j_wbufsize = n;
776         journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
777         if (!journal->j_wbuf) {
778                 printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
779                         __FUNCTION__);
780                 kfree(journal);
781                 return NULL;
782         }
783
784         err = jbd2_journal_bmap(journal, 0, &blocknr);
785         /* If that failed, give up */
786         if (err) {
787                 printk(KERN_ERR "%s: Cannnot locate journal superblock\n",
788                        __FUNCTION__);
789                 kfree(journal);
790                 return NULL;
791         }
792
793         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
794         J_ASSERT(bh != NULL);
795         journal->j_sb_buffer = bh;
796         journal->j_superblock = (journal_superblock_t *)bh->b_data;
797
798         return journal;
799 }
800
801 /*
802  * If the journal init or create aborts, we need to mark the journal
803  * superblock as being NULL to prevent the journal destroy from writing
804  * back a bogus superblock.
805  */
806 static void journal_fail_superblock (journal_t *journal)
807 {
808         struct buffer_head *bh = journal->j_sb_buffer;
809         brelse(bh);
810         journal->j_sb_buffer = NULL;
811 }
812
813 /*
814  * Given a journal_t structure, initialise the various fields for
815  * startup of a new journaling session.  We use this both when creating
816  * a journal, and after recovering an old journal to reset it for
817  * subsequent use.
818  */
819
820 static int journal_reset(journal_t *journal)
821 {
822         journal_superblock_t *sb = journal->j_superblock;
823         unsigned long long first, last;
824
825         first = be32_to_cpu(sb->s_first);
826         last = be32_to_cpu(sb->s_maxlen);
827
828         journal->j_first = first;
829         journal->j_last = last;
830
831         journal->j_head = first;
832         journal->j_tail = first;
833         journal->j_free = last - first;
834
835         journal->j_tail_sequence = journal->j_transaction_sequence;
836         journal->j_commit_sequence = journal->j_transaction_sequence - 1;
837         journal->j_commit_request = journal->j_commit_sequence;
838
839         journal->j_max_transaction_buffers = journal->j_maxlen / 4;
840
841         /* Add the dynamic fields and write it to disk. */
842         jbd2_journal_update_superblock(journal, 1);
843         jbd2_journal_start_thread(journal);
844         return 0;
845 }
846
847 /**
848  * int jbd2_journal_create() - Initialise the new journal file
849  * @journal: Journal to create. This structure must have been initialised
850  *
851  * Given a journal_t structure which tells us which disk blocks we can
852  * use, create a new journal superblock and initialise all of the
853  * journal fields from scratch.
854  **/
855 int jbd2_journal_create(journal_t *journal)
856 {
857         unsigned long long blocknr;
858         struct buffer_head *bh;
859         journal_superblock_t *sb;
860         int i, err;
861
862         if (journal->j_maxlen < JBD2_MIN_JOURNAL_BLOCKS) {
863                 printk (KERN_ERR "Journal length (%d blocks) too short.\n",
864                         journal->j_maxlen);
865                 journal_fail_superblock(journal);
866                 return -EINVAL;
867         }
868
869         if (journal->j_inode == NULL) {
870                 /*
871                  * We don't know what block to start at!
872                  */
873                 printk(KERN_EMERG
874                        "%s: creation of journal on external device!\n",
875                        __FUNCTION__);
876                 BUG();
877         }
878
879         /* Zero out the entire journal on disk.  We cannot afford to
880            have any blocks on disk beginning with JBD2_MAGIC_NUMBER. */
881         jbd_debug(1, "JBD: Zeroing out journal blocks...\n");
882         for (i = 0; i < journal->j_maxlen; i++) {
883                 err = jbd2_journal_bmap(journal, i, &blocknr);
884                 if (err)
885                         return err;
886                 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
887                 lock_buffer(bh);
888                 memset (bh->b_data, 0, journal->j_blocksize);
889                 BUFFER_TRACE(bh, "marking dirty");
890                 mark_buffer_dirty(bh);
891                 BUFFER_TRACE(bh, "marking uptodate");
892                 set_buffer_uptodate(bh);
893                 unlock_buffer(bh);
894                 __brelse(bh);
895         }
896
897         sync_blockdev(journal->j_dev);
898         jbd_debug(1, "JBD: journal cleared.\n");
899
900         /* OK, fill in the initial static fields in the new superblock */
901         sb = journal->j_superblock;
902
903         sb->s_header.h_magic     = cpu_to_be32(JBD2_MAGIC_NUMBER);
904         sb->s_header.h_blocktype = cpu_to_be32(JBD2_SUPERBLOCK_V2);
905
906         sb->s_blocksize = cpu_to_be32(journal->j_blocksize);
907         sb->s_maxlen    = cpu_to_be32(journal->j_maxlen);
908         sb->s_first     = cpu_to_be32(1);
909
910         journal->j_transaction_sequence = 1;
911
912         journal->j_flags &= ~JBD2_ABORT;
913         journal->j_format_version = 2;
914
915         return journal_reset(journal);
916 }
917
918 /**
919  * void jbd2_journal_update_superblock() - Update journal sb on disk.
920  * @journal: The journal to update.
921  * @wait: Set to '0' if you don't want to wait for IO completion.
922  *
923  * Update a journal's dynamic superblock fields and write it to disk,
924  * optionally waiting for the IO to complete.
925  */
926 void jbd2_journal_update_superblock(journal_t *journal, int wait)
927 {
928         journal_superblock_t *sb = journal->j_superblock;
929         struct buffer_head *bh = journal->j_sb_buffer;
930
931         /*
932          * As a special case, if the on-disk copy is already marked as needing
933          * no recovery (s_start == 0) and there are no outstanding transactions
934          * in the filesystem, then we can safely defer the superblock update
935          * until the next commit by setting JBD2_FLUSHED.  This avoids
936          * attempting a write to a potential-readonly device.
937          */
938         if (sb->s_start == 0 && journal->j_tail_sequence ==
939                                 journal->j_transaction_sequence) {
940                 jbd_debug(1,"JBD: Skipping superblock update on recovered sb "
941                         "(start %ld, seq %d, errno %d)\n",
942                         journal->j_tail, journal->j_tail_sequence,
943                         journal->j_errno);
944                 goto out;
945         }
946
947         spin_lock(&journal->j_state_lock);
948         jbd_debug(1,"JBD: updating superblock (start %ld, seq %d, errno %d)\n",
949                   journal->j_tail, journal->j_tail_sequence, journal->j_errno);
950
951         sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
952         sb->s_start    = cpu_to_be32(journal->j_tail);
953         sb->s_errno    = cpu_to_be32(journal->j_errno);
954         spin_unlock(&journal->j_state_lock);
955
956         BUFFER_TRACE(bh, "marking dirty");
957         mark_buffer_dirty(bh);
958         if (wait)
959                 sync_dirty_buffer(bh);
960         else
961                 ll_rw_block(SWRITE, 1, &bh);
962
963 out:
964         /* If we have just flushed the log (by marking s_start==0), then
965          * any future commit will have to be careful to update the
966          * superblock again to re-record the true start of the log. */
967
968         spin_lock(&journal->j_state_lock);
969         if (sb->s_start)
970                 journal->j_flags &= ~JBD2_FLUSHED;
971         else
972                 journal->j_flags |= JBD2_FLUSHED;
973         spin_unlock(&journal->j_state_lock);
974 }
975
976 /*
977  * Read the superblock for a given journal, performing initial
978  * validation of the format.
979  */
980
981 static int journal_get_superblock(journal_t *journal)
982 {
983         struct buffer_head *bh;
984         journal_superblock_t *sb;
985         int err = -EIO;
986
987         bh = journal->j_sb_buffer;
988
989         J_ASSERT(bh != NULL);
990         if (!buffer_uptodate(bh)) {
991                 ll_rw_block(READ, 1, &bh);
992                 wait_on_buffer(bh);
993                 if (!buffer_uptodate(bh)) {
994                         printk (KERN_ERR
995                                 "JBD: IO error reading journal superblock\n");
996                         goto out;
997                 }
998         }
999
1000         sb = journal->j_superblock;
1001
1002         err = -EINVAL;
1003
1004         if (sb->s_header.h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER) ||
1005             sb->s_blocksize != cpu_to_be32(journal->j_blocksize)) {
1006                 printk(KERN_WARNING "JBD: no valid journal superblock found\n");
1007                 goto out;
1008         }
1009
1010         switch(be32_to_cpu(sb->s_header.h_blocktype)) {
1011         case JBD2_SUPERBLOCK_V1:
1012                 journal->j_format_version = 1;
1013                 break;
1014         case JBD2_SUPERBLOCK_V2:
1015                 journal->j_format_version = 2;
1016                 break;
1017         default:
1018                 printk(KERN_WARNING "JBD: unrecognised superblock format ID\n");
1019                 goto out;
1020         }
1021
1022         if (be32_to_cpu(sb->s_maxlen) < journal->j_maxlen)
1023                 journal->j_maxlen = be32_to_cpu(sb->s_maxlen);
1024         else if (be32_to_cpu(sb->s_maxlen) > journal->j_maxlen) {
1025                 printk (KERN_WARNING "JBD: journal file too short\n");
1026                 goto out;
1027         }
1028
1029         return 0;
1030
1031 out:
1032         journal_fail_superblock(journal);
1033         return err;
1034 }
1035
1036 /*
1037  * Load the on-disk journal superblock and read the key fields into the
1038  * journal_t.
1039  */
1040
1041 static int load_superblock(journal_t *journal)
1042 {
1043         int err;
1044         journal_superblock_t *sb;
1045
1046         err = journal_get_superblock(journal);
1047         if (err)
1048                 return err;
1049
1050         sb = journal->j_superblock;
1051
1052         journal->j_tail_sequence = be32_to_cpu(sb->s_sequence);
1053         journal->j_tail = be32_to_cpu(sb->s_start);
1054         journal->j_first = be32_to_cpu(sb->s_first);
1055         journal->j_last = be32_to_cpu(sb->s_maxlen);
1056         journal->j_errno = be32_to_cpu(sb->s_errno);
1057
1058         return 0;
1059 }
1060
1061
1062 /**
1063  * int jbd2_journal_load() - Read journal from disk.
1064  * @journal: Journal to act on.
1065  *
1066  * Given a journal_t structure which tells us which disk blocks contain
1067  * a journal, read the journal from disk to initialise the in-memory
1068  * structures.
1069  */
1070 int jbd2_journal_load(journal_t *journal)
1071 {
1072         int err;
1073         journal_superblock_t *sb;
1074
1075         err = load_superblock(journal);
1076         if (err)
1077                 return err;
1078
1079         sb = journal->j_superblock;
1080         /* If this is a V2 superblock, then we have to check the
1081          * features flags on it. */
1082
1083         if (journal->j_format_version >= 2) {
1084                 if ((sb->s_feature_ro_compat &
1085                      ~cpu_to_be32(JBD2_KNOWN_ROCOMPAT_FEATURES)) ||
1086                     (sb->s_feature_incompat &
1087                      ~cpu_to_be32(JBD2_KNOWN_INCOMPAT_FEATURES))) {
1088                         printk (KERN_WARNING
1089                                 "JBD: Unrecognised features on journal\n");
1090                         return -EINVAL;
1091                 }
1092         }
1093
1094         /*
1095          * Create a slab for this blocksize
1096          */
1097         err = jbd2_journal_create_jbd_slab(be32_to_cpu(sb->s_blocksize));
1098         if (err)
1099                 return err;
1100
1101         /* Let the recovery code check whether it needs to recover any
1102          * data from the journal. */
1103         if (jbd2_journal_recover(journal))
1104                 goto recovery_error;
1105
1106         /* OK, we've finished with the dynamic journal bits:
1107          * reinitialise the dynamic contents of the superblock in memory
1108          * and reset them on disk. */
1109         if (journal_reset(journal))
1110                 goto recovery_error;
1111
1112         journal->j_flags &= ~JBD2_ABORT;
1113         journal->j_flags |= JBD2_LOADED;
1114         return 0;
1115
1116 recovery_error:
1117         printk (KERN_WARNING "JBD: recovery failed\n");
1118         return -EIO;
1119 }
1120
1121 /**
1122  * void jbd2_journal_destroy() - Release a journal_t structure.
1123  * @journal: Journal to act on.
1124  *
1125  * Release a journal_t structure once it is no longer in use by the
1126  * journaled object.
1127  */
1128 void jbd2_journal_destroy(journal_t *journal)
1129 {
1130         /* Wait for the commit thread to wake up and die. */
1131         journal_kill_thread(journal);
1132
1133         /* Force a final log commit */
1134         if (journal->j_running_transaction)
1135                 jbd2_journal_commit_transaction(journal);
1136
1137         /* Force any old transactions to disk */
1138
1139         /* Totally anal locking here... */
1140         spin_lock(&journal->j_list_lock);
1141         while (journal->j_checkpoint_transactions != NULL) {
1142                 spin_unlock(&journal->j_list_lock);
1143                 jbd2_log_do_checkpoint(journal);
1144                 spin_lock(&journal->j_list_lock);
1145         }
1146
1147         J_ASSERT(journal->j_running_transaction == NULL);
1148         J_ASSERT(journal->j_committing_transaction == NULL);
1149         J_ASSERT(journal->j_checkpoint_transactions == NULL);
1150         spin_unlock(&journal->j_list_lock);
1151
1152         /* We can now mark the journal as empty. */
1153         journal->j_tail = 0;
1154         journal->j_tail_sequence = ++journal->j_transaction_sequence;
1155         if (journal->j_sb_buffer) {
1156                 jbd2_journal_update_superblock(journal, 1);
1157                 brelse(journal->j_sb_buffer);
1158         }
1159
1160         if (journal->j_inode)
1161                 iput(journal->j_inode);
1162         if (journal->j_revoke)
1163                 jbd2_journal_destroy_revoke(journal);
1164         kfree(journal->j_wbuf);
1165         kfree(journal);
1166 }
1167
1168
1169 /**
1170  *int jbd2_journal_check_used_features () - Check if features specified are used.
1171  * @journal: Journal to check.
1172  * @compat: bitmask of compatible features
1173  * @ro: bitmask of features that force read-only mount
1174  * @incompat: bitmask of incompatible features
1175  *
1176  * Check whether the journal uses all of a given set of
1177  * features.  Return true (non-zero) if it does.
1178  **/
1179
1180 int jbd2_journal_check_used_features (journal_t *journal, unsigned long compat,
1181                                  unsigned long ro, unsigned long incompat)
1182 {
1183         journal_superblock_t *sb;
1184
1185         if (!compat && !ro && !incompat)
1186                 return 1;
1187         if (journal->j_format_version == 1)
1188                 return 0;
1189
1190         sb = journal->j_superblock;
1191
1192         if (((be32_to_cpu(sb->s_feature_compat) & compat) == compat) &&
1193             ((be32_to_cpu(sb->s_feature_ro_compat) & ro) == ro) &&
1194             ((be32_to_cpu(sb->s_feature_incompat) & incompat) == incompat))
1195                 return 1;
1196
1197         return 0;
1198 }
1199
1200 /**
1201  * int jbd2_journal_check_available_features() - Check feature set in journalling layer
1202  * @journal: Journal to check.
1203  * @compat: bitmask of compatible features
1204  * @ro: bitmask of features that force read-only mount
1205  * @incompat: bitmask of incompatible features
1206  *
1207  * Check whether the journaling code supports the use of
1208  * all of a given set of features on this journal.  Return true
1209  * (non-zero) if it can. */
1210
1211 int jbd2_journal_check_available_features (journal_t *journal, unsigned long compat,
1212                                       unsigned long ro, unsigned long incompat)
1213 {
1214         journal_superblock_t *sb;
1215
1216         if (!compat && !ro && !incompat)
1217                 return 1;
1218
1219         sb = journal->j_superblock;
1220
1221         /* We can support any known requested features iff the
1222          * superblock is in version 2.  Otherwise we fail to support any
1223          * extended sb features. */
1224
1225         if (journal->j_format_version != 2)
1226                 return 0;
1227
1228         if ((compat   & JBD2_KNOWN_COMPAT_FEATURES) == compat &&
1229             (ro       & JBD2_KNOWN_ROCOMPAT_FEATURES) == ro &&
1230             (incompat & JBD2_KNOWN_INCOMPAT_FEATURES) == incompat)
1231                 return 1;
1232
1233         return 0;
1234 }
1235
1236 /**
1237  * int jbd2_journal_set_features () - Mark a given journal feature in the superblock
1238  * @journal: Journal to act on.
1239  * @compat: bitmask of compatible features
1240  * @ro: bitmask of features that force read-only mount
1241  * @incompat: bitmask of incompatible features
1242  *
1243  * Mark a given journal feature as present on the
1244  * superblock.  Returns true if the requested features could be set.
1245  *
1246  */
1247
1248 int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
1249                           unsigned long ro, unsigned long incompat)
1250 {
1251         journal_superblock_t *sb;
1252
1253         if (jbd2_journal_check_used_features(journal, compat, ro, incompat))
1254                 return 1;
1255
1256         if (!jbd2_journal_check_available_features(journal, compat, ro, incompat))
1257                 return 0;
1258
1259         jbd_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n",
1260                   compat, ro, incompat);
1261
1262         sb = journal->j_superblock;
1263
1264         sb->s_feature_compat    |= cpu_to_be32(compat);
1265         sb->s_feature_ro_compat |= cpu_to_be32(ro);
1266         sb->s_feature_incompat  |= cpu_to_be32(incompat);
1267
1268         return 1;
1269 }
1270
1271
1272 /**
1273  * int jbd2_journal_update_format () - Update on-disk journal structure.
1274  * @journal: Journal to act on.
1275  *
1276  * Given an initialised but unloaded journal struct, poke about in the
1277  * on-disk structure to update it to the most recent supported version.
1278  */
1279 int jbd2_journal_update_format (journal_t *journal)
1280 {
1281         journal_superblock_t *sb;
1282         int err;
1283
1284         err = journal_get_superblock(journal);
1285         if (err)
1286                 return err;
1287
1288         sb = journal->j_superblock;
1289
1290         switch (be32_to_cpu(sb->s_header.h_blocktype)) {
1291         case JBD2_SUPERBLOCK_V2:
1292                 return 0;
1293         case JBD2_SUPERBLOCK_V1:
1294                 return journal_convert_superblock_v1(journal, sb);
1295         default:
1296                 break;
1297         }
1298         return -EINVAL;
1299 }
1300
1301 static int journal_convert_superblock_v1(journal_t *journal,
1302                                          journal_superblock_t *sb)
1303 {
1304         int offset, blocksize;
1305         struct buffer_head *bh;
1306
1307         printk(KERN_WARNING
1308                 "JBD: Converting superblock from version 1 to 2.\n");
1309
1310         /* Pre-initialise new fields to zero */
1311         offset = ((char *) &(sb->s_feature_compat)) - ((char *) sb);
1312         blocksize = be32_to_cpu(sb->s_blocksize);
1313         memset(&sb->s_feature_compat, 0, blocksize-offset);
1314
1315         sb->s_nr_users = cpu_to_be32(1);
1316         sb->s_header.h_blocktype = cpu_to_be32(JBD2_SUPERBLOCK_V2);
1317         journal->j_format_version = 2;
1318
1319         bh = journal->j_sb_buffer;
1320         BUFFER_TRACE(bh, "marking dirty");
1321         mark_buffer_dirty(bh);
1322         sync_dirty_buffer(bh);
1323         return 0;
1324 }
1325
1326
1327 /**
1328  * int jbd2_journal_flush () - Flush journal
1329  * @journal: Journal to act on.
1330  *
1331  * Flush all data for a given journal to disk and empty the journal.
1332  * Filesystems can use this when remounting readonly to ensure that
1333  * recovery does not need to happen on remount.
1334  */
1335
1336 int jbd2_journal_flush(journal_t *journal)
1337 {
1338         int err = 0;
1339         transaction_t *transaction = NULL;
1340         unsigned long old_tail;
1341
1342         spin_lock(&journal->j_state_lock);
1343
1344         /* Force everything buffered to the log... */
1345         if (journal->j_running_transaction) {
1346                 transaction = journal->j_running_transaction;
1347                 __jbd2_log_start_commit(journal, transaction->t_tid);
1348         } else if (journal->j_committing_transaction)
1349                 transaction = journal->j_committing_transaction;
1350
1351         /* Wait for the log commit to complete... */
1352         if (transaction) {
1353                 tid_t tid = transaction->t_tid;
1354
1355                 spin_unlock(&journal->j_state_lock);
1356                 jbd2_log_wait_commit(journal, tid);
1357         } else {
1358                 spin_unlock(&journal->j_state_lock);
1359         }
1360
1361         /* ...and flush everything in the log out to disk. */
1362         spin_lock(&journal->j_list_lock);
1363         while (!err && journal->j_checkpoint_transactions != NULL) {
1364                 spin_unlock(&journal->j_list_lock);
1365                 err = jbd2_log_do_checkpoint(journal);
1366                 spin_lock(&journal->j_list_lock);
1367         }
1368         spin_unlock(&journal->j_list_lock);
1369         jbd2_cleanup_journal_tail(journal);
1370
1371         /* Finally, mark the journal as really needing no recovery.
1372          * This sets s_start==0 in the underlying superblock, which is
1373          * the magic code for a fully-recovered superblock.  Any future
1374          * commits of data to the journal will restore the current
1375          * s_start value. */
1376         spin_lock(&journal->j_state_lock);
1377         old_tail = journal->j_tail;
1378         journal->j_tail = 0;
1379         spin_unlock(&journal->j_state_lock);
1380         jbd2_journal_update_superblock(journal, 1);
1381         spin_lock(&journal->j_state_lock);
1382         journal->j_tail = old_tail;
1383
1384         J_ASSERT(!journal->j_running_transaction);
1385         J_ASSERT(!journal->j_committing_transaction);
1386         J_ASSERT(!journal->j_checkpoint_transactions);
1387         J_ASSERT(journal->j_head == journal->j_tail);
1388         J_ASSERT(journal->j_tail_sequence == journal->j_transaction_sequence);
1389         spin_unlock(&journal->j_state_lock);
1390         return err;
1391 }
1392
1393 /**
1394  * int jbd2_journal_wipe() - Wipe journal contents
1395  * @journal: Journal to act on.
1396  * @write: flag (see below)
1397  *
1398  * Wipe out all of the contents of a journal, safely.  This will produce
1399  * a warning if the journal contains any valid recovery information.
1400  * Must be called between journal_init_*() and jbd2_journal_load().
1401  *
1402  * If 'write' is non-zero, then we wipe out the journal on disk; otherwise
1403  * we merely suppress recovery.
1404  */
1405
1406 int jbd2_journal_wipe(journal_t *journal, int write)
1407 {
1408         journal_superblock_t *sb;
1409         int err = 0;
1410
1411         J_ASSERT (!(journal->j_flags & JBD2_LOADED));
1412
1413         err = load_superblock(journal);
1414         if (err)
1415                 return err;
1416
1417         sb = journal->j_superblock;
1418
1419         if (!journal->j_tail)
1420                 goto no_recovery;
1421
1422         printk (KERN_WARNING "JBD: %s recovery information on journal\n",
1423                 write ? "Clearing" : "Ignoring");
1424
1425         err = jbd2_journal_skip_recovery(journal);
1426         if (write)
1427                 jbd2_journal_update_superblock(journal, 1);
1428
1429  no_recovery:
1430         return err;
1431 }
1432
1433 /*
1434  * journal_dev_name: format a character string to describe on what
1435  * device this journal is present.
1436  */
1437
1438 static const char *journal_dev_name(journal_t *journal, char *buffer)
1439 {
1440         struct block_device *bdev;
1441
1442         if (journal->j_inode)
1443                 bdev = journal->j_inode->i_sb->s_bdev;
1444         else
1445                 bdev = journal->j_dev;
1446
1447         return bdevname(bdev, buffer);
1448 }
1449
1450 /*
1451  * Journal abort has very specific semantics, which we describe
1452  * for journal abort.
1453  *
1454  * Two internal function, which provide abort to te jbd layer
1455  * itself are here.
1456  */
1457
1458 /*
1459  * Quick version for internal journal use (doesn't lock the journal).
1460  * Aborts hard --- we mark the abort as occurred, but do _nothing_ else,
1461  * and don't attempt to make any other journal updates.
1462  */
1463 void __jbd2_journal_abort_hard(journal_t *journal)
1464 {
1465         transaction_t *transaction;
1466         char b[BDEVNAME_SIZE];
1467
1468         if (journal->j_flags & JBD2_ABORT)
1469                 return;
1470
1471         printk(KERN_ERR "Aborting journal on device %s.\n",
1472                 journal_dev_name(journal, b));
1473
1474         spin_lock(&journal->j_state_lock);
1475         journal->j_flags |= JBD2_ABORT;
1476         transaction = journal->j_running_transaction;
1477         if (transaction)
1478                 __jbd2_log_start_commit(journal, transaction->t_tid);
1479         spin_unlock(&journal->j_state_lock);
1480 }
1481
1482 /* Soft abort: record the abort error status in the journal superblock,
1483  * but don't do any other IO. */
1484 static void __journal_abort_soft (journal_t *journal, int errno)
1485 {
1486         if (journal->j_flags & JBD2_ABORT)
1487                 return;
1488
1489         if (!journal->j_errno)
1490                 journal->j_errno = errno;
1491
1492         __jbd2_journal_abort_hard(journal);
1493
1494         if (errno)
1495                 jbd2_journal_update_superblock(journal, 1);
1496 }
1497
1498 /**
1499  * void jbd2_journal_abort () - Shutdown the journal immediately.
1500  * @journal: the journal to shutdown.
1501  * @errno:   an error number to record in the journal indicating
1502  *           the reason for the shutdown.
1503  *
1504  * Perform a complete, immediate shutdown of the ENTIRE
1505  * journal (not of a single transaction).  This operation cannot be
1506  * undone without closing and reopening the journal.
1507  *
1508  * The jbd2_journal_abort function is intended to support higher level error
1509  * recovery mechanisms such as the ext2/ext3 remount-readonly error
1510  * mode.
1511  *
1512  * Journal abort has very specific semantics.  Any existing dirty,
1513  * unjournaled buffers in the main filesystem will still be written to
1514  * disk by bdflush, but the journaling mechanism will be suspended
1515  * immediately and no further transaction commits will be honoured.
1516  *
1517  * Any dirty, journaled buffers will be written back to disk without
1518  * hitting the journal.  Atomicity cannot be guaranteed on an aborted
1519  * filesystem, but we _do_ attempt to leave as much data as possible
1520  * behind for fsck to use for cleanup.
1521  *
1522  * Any attempt to get a new transaction handle on a journal which is in
1523  * ABORT state will just result in an -EROFS error return.  A
1524  * jbd2_journal_stop on an existing handle will return -EIO if we have
1525  * entered abort state during the update.
1526  *
1527  * Recursive transactions are not disturbed by journal abort until the
1528  * final jbd2_journal_stop, which will receive the -EIO error.
1529  *
1530  * Finally, the jbd2_journal_abort call allows the caller to supply an errno
1531  * which will be recorded (if possible) in the journal superblock.  This
1532  * allows a client to record failure conditions in the middle of a
1533  * transaction without having to complete the transaction to record the
1534  * failure to disk.  ext3_error, for example, now uses this
1535  * functionality.
1536  *
1537  * Errors which originate from within the journaling layer will NOT
1538  * supply an errno; a null errno implies that absolutely no further
1539  * writes are done to the journal (unless there are any already in
1540  * progress).
1541  *
1542  */
1543
1544 void jbd2_journal_abort(journal_t *journal, int errno)
1545 {
1546         __journal_abort_soft(journal, errno);
1547 }
1548
1549 /**
1550  * int jbd2_journal_errno () - returns the journal's error state.
1551  * @journal: journal to examine.
1552  *
1553  * This is the errno numbet set with jbd2_journal_abort(), the last
1554  * time the journal was mounted - if the journal was stopped
1555  * without calling abort this will be 0.
1556  *
1557  * If the journal has been aborted on this mount time -EROFS will
1558  * be returned.
1559  */
1560 int jbd2_journal_errno(journal_t *journal)
1561 {
1562         int err;
1563
1564         spin_lock(&journal->j_state_lock);
1565         if (journal->j_flags & JBD2_ABORT)
1566                 err = -EROFS;
1567         else
1568                 err = journal->j_errno;
1569         spin_unlock(&journal->j_state_lock);
1570         return err;
1571 }
1572
1573 /**
1574  * int jbd2_journal_clear_err () - clears the journal's error state
1575  * @journal: journal to act on.
1576  *
1577  * An error must be cleared or Acked to take a FS out of readonly
1578  * mode.
1579  */
1580 int jbd2_journal_clear_err(journal_t *journal)
1581 {
1582         int err = 0;
1583
1584         spin_lock(&journal->j_state_lock);
1585         if (journal->j_flags & JBD2_ABORT)
1586                 err = -EROFS;
1587         else
1588                 journal->j_errno = 0;
1589         spin_unlock(&journal->j_state_lock);
1590         return err;
1591 }
1592
1593 /**
1594  * void jbd2_journal_ack_err() - Ack journal err.
1595  * @journal: journal to act on.
1596  *
1597  * An error must be cleared or Acked to take a FS out of readonly
1598  * mode.
1599  */
1600 void jbd2_journal_ack_err(journal_t *journal)
1601 {
1602         spin_lock(&journal->j_state_lock);
1603         if (journal->j_errno)
1604                 journal->j_flags |= JBD2_ACK_ERR;
1605         spin_unlock(&journal->j_state_lock);
1606 }
1607
1608 int jbd2_journal_blocks_per_page(struct inode *inode)
1609 {
1610         return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
1611 }
1612
1613 /*
1614  * helper functions to deal with 32 or 64bit block numbers.
1615  */
1616 size_t journal_tag_bytes(journal_t *journal)
1617 {
1618         if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
1619                 return JBD_TAG_SIZE64;
1620         else
1621                 return JBD_TAG_SIZE32;
1622 }
1623
1624 /*
1625  * Simple support for retrying memory allocations.  Introduced to help to
1626  * debug different VM deadlock avoidance strategies.
1627  */
1628 void * __jbd2_kmalloc (const char *where, size_t size, gfp_t flags, int retry)
1629 {
1630         return kmalloc(size, flags | (retry ? __GFP_NOFAIL : 0));
1631 }
1632
1633 /*
1634  * jbd slab management: create 1k, 2k, 4k, 8k slabs as needed
1635  * and allocate frozen and commit buffers from these slabs.
1636  *
1637  * Reason for doing this is to avoid, SLAB_DEBUG - since it could
1638  * cause bh to cross page boundary.
1639  */
1640
1641 #define JBD_MAX_SLABS 5
1642 #define JBD_SLAB_INDEX(size)  (size >> 11)
1643
1644 static struct kmem_cache *jbd_slab[JBD_MAX_SLABS];
1645 static const char *jbd_slab_names[JBD_MAX_SLABS] = {
1646         "jbd2_1k", "jbd2_2k", "jbd2_4k", NULL, "jbd2_8k"
1647 };
1648
1649 static void jbd2_journal_destroy_jbd_slabs(void)
1650 {
1651         int i;
1652
1653         for (i = 0; i < JBD_MAX_SLABS; i++) {
1654                 if (jbd_slab[i])
1655                         kmem_cache_destroy(jbd_slab[i]);
1656                 jbd_slab[i] = NULL;
1657         }
1658 }
1659
1660 static int jbd2_journal_create_jbd_slab(size_t slab_size)
1661 {
1662         int i = JBD_SLAB_INDEX(slab_size);
1663
1664         BUG_ON(i >= JBD_MAX_SLABS);
1665
1666         /*
1667          * Check if we already have a slab created for this size
1668          */
1669         if (jbd_slab[i])
1670                 return 0;
1671
1672         /*
1673          * Create a slab and force alignment to be same as slabsize -
1674          * this will make sure that allocations won't cross the page
1675          * boundary.
1676          */
1677         jbd_slab[i] = kmem_cache_create(jbd_slab_names[i],
1678                                 slab_size, slab_size, 0, NULL, NULL);
1679         if (!jbd_slab[i]) {
1680                 printk(KERN_EMERG "JBD: no memory for jbd_slab cache\n");
1681                 return -ENOMEM;
1682         }
1683         return 0;
1684 }
1685
1686 void * jbd2_slab_alloc(size_t size, gfp_t flags)
1687 {
1688         int idx;
1689
1690         idx = JBD_SLAB_INDEX(size);
1691         BUG_ON(jbd_slab[idx] == NULL);
1692         return kmem_cache_alloc(jbd_slab[idx], flags | __GFP_NOFAIL);
1693 }
1694
1695 void jbd2_slab_free(void *ptr,  size_t size)
1696 {
1697         int idx;
1698
1699         idx = JBD_SLAB_INDEX(size);
1700         BUG_ON(jbd_slab[idx] == NULL);
1701         kmem_cache_free(jbd_slab[idx], ptr);
1702 }
1703
1704 /*
1705  * Journal_head storage management
1706  */
1707 static struct kmem_cache *jbd2_journal_head_cache;
1708 #ifdef CONFIG_JBD_DEBUG
1709 static atomic_t nr_journal_heads = ATOMIC_INIT(0);
1710 #endif
1711
1712 static int journal_init_jbd2_journal_head_cache(void)
1713 {
1714         int retval;
1715
1716         J_ASSERT(jbd2_journal_head_cache == 0);
1717         jbd2_journal_head_cache = kmem_cache_create("jbd2_journal_head",
1718                                 sizeof(struct journal_head),
1719                                 0,              /* offset */
1720                                 0,              /* flags */
1721                                 NULL,           /* ctor */
1722                                 NULL);          /* dtor */
1723         retval = 0;
1724         if (jbd2_journal_head_cache == 0) {
1725                 retval = -ENOMEM;
1726                 printk(KERN_EMERG "JBD: no memory for journal_head cache\n");
1727         }
1728         return retval;
1729 }
1730
1731 static void jbd2_journal_destroy_jbd2_journal_head_cache(void)
1732 {
1733         J_ASSERT(jbd2_journal_head_cache != NULL);
1734         kmem_cache_destroy(jbd2_journal_head_cache);
1735         jbd2_journal_head_cache = NULL;
1736 }
1737
1738 /*
1739  * journal_head splicing and dicing
1740  */
1741 static struct journal_head *journal_alloc_journal_head(void)
1742 {
1743         struct journal_head *ret;
1744         static unsigned long last_warning;
1745
1746 #ifdef CONFIG_JBD_DEBUG
1747         atomic_inc(&nr_journal_heads);
1748 #endif
1749         ret = kmem_cache_alloc(jbd2_journal_head_cache, GFP_NOFS);
1750         if (ret == 0) {
1751                 jbd_debug(1, "out of memory for journal_head\n");
1752                 if (time_after(jiffies, last_warning + 5*HZ)) {
1753                         printk(KERN_NOTICE "ENOMEM in %s, retrying.\n",
1754                                __FUNCTION__);
1755                         last_warning = jiffies;
1756                 }
1757                 while (ret == 0) {
1758                         yield();
1759                         ret = kmem_cache_alloc(jbd2_journal_head_cache, GFP_NOFS);
1760                 }
1761         }
1762         return ret;
1763 }
1764
1765 static void journal_free_journal_head(struct journal_head *jh)
1766 {
1767 #ifdef CONFIG_JBD_DEBUG
1768         atomic_dec(&nr_journal_heads);
1769         memset(jh, JBD_POISON_FREE, sizeof(*jh));
1770 #endif
1771         kmem_cache_free(jbd2_journal_head_cache, jh);
1772 }
1773
1774 /*
1775  * A journal_head is attached to a buffer_head whenever JBD has an
1776  * interest in the buffer.
1777  *
1778  * Whenever a buffer has an attached journal_head, its ->b_state:BH_JBD bit
1779  * is set.  This bit is tested in core kernel code where we need to take
1780  * JBD-specific actions.  Testing the zeroness of ->b_private is not reliable
1781  * there.
1782  *
1783  * When a buffer has its BH_JBD bit set, its ->b_count is elevated by one.
1784  *
1785  * When a buffer has its BH_JBD bit set it is immune from being released by
1786  * core kernel code, mainly via ->b_count.
1787  *
1788  * A journal_head may be detached from its buffer_head when the journal_head's
1789  * b_transaction, b_cp_transaction and b_next_transaction pointers are NULL.
1790  * Various places in JBD call jbd2_journal_remove_journal_head() to indicate that the
1791  * journal_head can be dropped if needed.
1792  *
1793  * Various places in the kernel want to attach a journal_head to a buffer_head
1794  * _before_ attaching the journal_head to a transaction.  To protect the
1795  * journal_head in this situation, jbd2_journal_add_journal_head elevates the
1796  * journal_head's b_jcount refcount by one.  The caller must call
1797  * jbd2_journal_put_journal_head() to undo this.
1798  *
1799  * So the typical usage would be:
1800  *
1801  *      (Attach a journal_head if needed.  Increments b_jcount)
1802  *      struct journal_head *jh = jbd2_journal_add_journal_head(bh);
1803  *      ...
1804  *      jh->b_transaction = xxx;
1805  *      jbd2_journal_put_journal_head(jh);
1806  *
1807  * Now, the journal_head's b_jcount is zero, but it is safe from being released
1808  * because it has a non-zero b_transaction.
1809  */
1810
1811 /*
1812  * Give a buffer_head a journal_head.
1813  *
1814  * Doesn't need the journal lock.
1815  * May sleep.
1816  */
1817 struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh)
1818 {
1819         struct journal_head *jh;
1820         struct journal_head *new_jh = NULL;
1821
1822 repeat:
1823         if (!buffer_jbd(bh)) {
1824                 new_jh = journal_alloc_journal_head();
1825                 memset(new_jh, 0, sizeof(*new_jh));
1826         }
1827
1828         jbd_lock_bh_journal_head(bh);
1829         if (buffer_jbd(bh)) {
1830                 jh = bh2jh(bh);
1831         } else {
1832                 J_ASSERT_BH(bh,
1833                         (atomic_read(&bh->b_count) > 0) ||
1834                         (bh->b_page && bh->b_page->mapping));
1835
1836                 if (!new_jh) {
1837                         jbd_unlock_bh_journal_head(bh);
1838                         goto repeat;
1839                 }
1840
1841                 jh = new_jh;
1842                 new_jh = NULL;          /* We consumed it */
1843                 set_buffer_jbd(bh);
1844                 bh->b_private = jh;
1845                 jh->b_bh = bh;
1846                 get_bh(bh);
1847                 BUFFER_TRACE(bh, "added journal_head");
1848         }
1849         jh->b_jcount++;
1850         jbd_unlock_bh_journal_head(bh);
1851         if (new_jh)
1852                 journal_free_journal_head(new_jh);
1853         return bh->b_private;
1854 }
1855
1856 /*
1857  * Grab a ref against this buffer_head's journal_head.  If it ended up not
1858  * having a journal_head, return NULL
1859  */
1860 struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh)
1861 {
1862         struct journal_head *jh = NULL;
1863
1864         jbd_lock_bh_journal_head(bh);
1865         if (buffer_jbd(bh)) {
1866                 jh = bh2jh(bh);
1867                 jh->b_jcount++;
1868         }
1869         jbd_unlock_bh_journal_head(bh);
1870         return jh;
1871 }
1872
1873 static void __journal_remove_journal_head(struct buffer_head *bh)
1874 {
1875         struct journal_head *jh = bh2jh(bh);
1876
1877         J_ASSERT_JH(jh, jh->b_jcount >= 0);
1878
1879         get_bh(bh);
1880         if (jh->b_jcount == 0) {
1881                 if (jh->b_transaction == NULL &&
1882                                 jh->b_next_transaction == NULL &&
1883                                 jh->b_cp_transaction == NULL) {
1884                         J_ASSERT_JH(jh, jh->b_jlist == BJ_None);
1885                         J_ASSERT_BH(bh, buffer_jbd(bh));
1886                         J_ASSERT_BH(bh, jh2bh(jh) == bh);
1887                         BUFFER_TRACE(bh, "remove journal_head");
1888                         if (jh->b_frozen_data) {
1889                                 printk(KERN_WARNING "%s: freeing "
1890                                                 "b_frozen_data\n",
1891                                                 __FUNCTION__);
1892                                 jbd2_slab_free(jh->b_frozen_data, bh->b_size);
1893                         }
1894                         if (jh->b_committed_data) {
1895                                 printk(KERN_WARNING "%s: freeing "
1896                                                 "b_committed_data\n",
1897                                                 __FUNCTION__);
1898                                 jbd2_slab_free(jh->b_committed_data, bh->b_size);
1899                         }
1900                         bh->b_private = NULL;
1901                         jh->b_bh = NULL;        /* debug, really */
1902                         clear_buffer_jbd(bh);
1903                         __brelse(bh);
1904                         journal_free_journal_head(jh);
1905                 } else {
1906                         BUFFER_TRACE(bh, "journal_head was locked");
1907                 }
1908         }
1909 }
1910
1911 /*
1912  * jbd2_journal_remove_journal_head(): if the buffer isn't attached to a transaction
1913  * and has a zero b_jcount then remove and release its journal_head.   If we did
1914  * see that the buffer is not used by any transaction we also "logically"
1915  * decrement ->b_count.
1916  *
1917  * We in fact take an additional increment on ->b_count as a convenience,
1918  * because the caller usually wants to do additional things with the bh
1919  * after calling here.
1920  * The caller of jbd2_journal_remove_journal_head() *must* run __brelse(bh) at some
1921  * time.  Once the caller has run __brelse(), the buffer is eligible for
1922  * reaping by try_to_free_buffers().
1923  */
1924 void jbd2_journal_remove_journal_head(struct buffer_head *bh)
1925 {
1926         jbd_lock_bh_journal_head(bh);
1927         __journal_remove_journal_head(bh);
1928         jbd_unlock_bh_journal_head(bh);
1929 }
1930
1931 /*
1932  * Drop a reference on the passed journal_head.  If it fell to zero then try to
1933  * release the journal_head from the buffer_head.
1934  */
1935 void jbd2_journal_put_journal_head(struct journal_head *jh)
1936 {
1937         struct buffer_head *bh = jh2bh(jh);
1938
1939         jbd_lock_bh_journal_head(bh);
1940         J_ASSERT_JH(jh, jh->b_jcount > 0);
1941         --jh->b_jcount;
1942         if (!jh->b_jcount && !jh->b_transaction) {
1943                 __journal_remove_journal_head(bh);
1944                 __brelse(bh);
1945         }
1946         jbd_unlock_bh_journal_head(bh);
1947 }
1948
1949 /*
1950  * /proc tunables
1951  */
1952 #if defined(CONFIG_JBD_DEBUG)
1953 int jbd2_journal_enable_debug;
1954 EXPORT_SYMBOL(jbd2_journal_enable_debug);
1955 #endif
1956
1957 #if defined(CONFIG_JBD_DEBUG) && defined(CONFIG_PROC_FS)
1958
1959 static struct proc_dir_entry *proc_jbd_debug;
1960
1961 static int read_jbd_debug(char *page, char **start, off_t off,
1962                           int count, int *eof, void *data)
1963 {
1964         int ret;
1965
1966         ret = sprintf(page + off, "%d\n", jbd2_journal_enable_debug);
1967         *eof = 1;
1968         return ret;
1969 }
1970
1971 static int write_jbd_debug(struct file *file, const char __user *buffer,
1972                            unsigned long count, void *data)
1973 {
1974         char buf[32];
1975
1976         if (count > ARRAY_SIZE(buf) - 1)
1977                 count = ARRAY_SIZE(buf) - 1;
1978         if (copy_from_user(buf, buffer, count))
1979                 return -EFAULT;
1980         buf[ARRAY_SIZE(buf) - 1] = '\0';
1981         jbd2_journal_enable_debug = simple_strtoul(buf, NULL, 10);
1982         return count;
1983 }
1984
1985 #define JBD_PROC_NAME "sys/fs/jbd2-debug"
1986
1987 static void __init create_jbd_proc_entry(void)
1988 {
1989         proc_jbd_debug = create_proc_entry(JBD_PROC_NAME, 0644, NULL);
1990         if (proc_jbd_debug) {
1991                 /* Why is this so hard? */
1992                 proc_jbd_debug->read_proc = read_jbd_debug;
1993                 proc_jbd_debug->write_proc = write_jbd_debug;
1994         }
1995 }
1996
1997 static void __exit jbd2_remove_jbd_proc_entry(void)
1998 {
1999         if (proc_jbd_debug)
2000                 remove_proc_entry(JBD_PROC_NAME, NULL);
2001 }
2002
2003 #else
2004
2005 #define create_jbd_proc_entry() do {} while (0)
2006 #define jbd2_remove_jbd_proc_entry() do {} while (0)
2007
2008 #endif
2009
2010 struct kmem_cache *jbd2_handle_cache;
2011
2012 static int __init journal_init_handle_cache(void)
2013 {
2014         jbd2_handle_cache = kmem_cache_create("jbd2_journal_handle",
2015                                 sizeof(handle_t),
2016                                 0,              /* offset */
2017                                 0,              /* flags */
2018                                 NULL,           /* ctor */
2019                                 NULL);          /* dtor */
2020         if (jbd2_handle_cache == NULL) {
2021                 printk(KERN_EMERG "JBD: failed to create handle cache\n");
2022                 return -ENOMEM;
2023         }
2024         return 0;
2025 }
2026
2027 static void jbd2_journal_destroy_handle_cache(void)
2028 {
2029         if (jbd2_handle_cache)
2030                 kmem_cache_destroy(jbd2_handle_cache);
2031 }
2032
2033 /*
2034  * Module startup and shutdown
2035  */
2036
2037 static int __init journal_init_caches(void)
2038 {
2039         int ret;
2040
2041         ret = jbd2_journal_init_revoke_caches();
2042         if (ret == 0)
2043                 ret = journal_init_jbd2_journal_head_cache();
2044         if (ret == 0)
2045                 ret = journal_init_handle_cache();
2046         return ret;
2047 }
2048
2049 static void jbd2_journal_destroy_caches(void)
2050 {
2051         jbd2_journal_destroy_revoke_caches();
2052         jbd2_journal_destroy_jbd2_journal_head_cache();
2053         jbd2_journal_destroy_handle_cache();
2054         jbd2_journal_destroy_jbd_slabs();
2055 }
2056
2057 static int __init journal_init(void)
2058 {
2059         int ret;
2060
2061         BUILD_BUG_ON(sizeof(struct journal_superblock_s) != 1024);
2062
2063         ret = journal_init_caches();
2064         if (ret != 0)
2065                 jbd2_journal_destroy_caches();
2066         create_jbd_proc_entry();
2067         return ret;
2068 }
2069
2070 static void __exit journal_exit(void)
2071 {
2072 #ifdef CONFIG_JBD_DEBUG
2073         int n = atomic_read(&nr_journal_heads);
2074         if (n)
2075                 printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n);
2076 #endif
2077         jbd2_remove_jbd_proc_entry();
2078         jbd2_journal_destroy_caches();
2079 }
2080
2081 MODULE_LICENSE("GPL");
2082 module_init(journal_init);
2083 module_exit(journal_exit);
2084