jbd2: clean up how the journal device name is printed
[linux-2.6.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/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 #include <linux/debugfs.h>
39 #include <linux/seq_file.h>
40
41 #include <asm/uaccess.h>
42 #include <asm/page.h>
43
44 EXPORT_SYMBOL(jbd2_journal_start);
45 EXPORT_SYMBOL(jbd2_journal_restart);
46 EXPORT_SYMBOL(jbd2_journal_extend);
47 EXPORT_SYMBOL(jbd2_journal_stop);
48 EXPORT_SYMBOL(jbd2_journal_lock_updates);
49 EXPORT_SYMBOL(jbd2_journal_unlock_updates);
50 EXPORT_SYMBOL(jbd2_journal_get_write_access);
51 EXPORT_SYMBOL(jbd2_journal_get_create_access);
52 EXPORT_SYMBOL(jbd2_journal_get_undo_access);
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_abort);
72 EXPORT_SYMBOL(jbd2_journal_errno);
73 EXPORT_SYMBOL(jbd2_journal_ack_err);
74 EXPORT_SYMBOL(jbd2_journal_clear_err);
75 EXPORT_SYMBOL(jbd2_log_wait_commit);
76 EXPORT_SYMBOL(jbd2_journal_start_commit);
77 EXPORT_SYMBOL(jbd2_journal_force_commit_nested);
78 EXPORT_SYMBOL(jbd2_journal_wipe);
79 EXPORT_SYMBOL(jbd2_journal_blocks_per_page);
80 EXPORT_SYMBOL(jbd2_journal_invalidatepage);
81 EXPORT_SYMBOL(jbd2_journal_try_to_free_buffers);
82 EXPORT_SYMBOL(jbd2_journal_force_commit);
83 EXPORT_SYMBOL(jbd2_journal_file_inode);
84 EXPORT_SYMBOL(jbd2_journal_init_jbd_inode);
85 EXPORT_SYMBOL(jbd2_journal_release_jbd_inode);
86 EXPORT_SYMBOL(jbd2_journal_begin_ordered_truncate);
87
88 static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *);
89 static void __journal_abort_soft (journal_t *journal, int errno);
90
91 /*
92  * Helper function used to manage commit timeouts
93  */
94
95 static void commit_timeout(unsigned long __data)
96 {
97         struct task_struct * p = (struct task_struct *) __data;
98
99         wake_up_process(p);
100 }
101
102 /*
103  * kjournald2: The main thread function used to manage a logging device
104  * journal.
105  *
106  * This kernel thread is responsible for two things:
107  *
108  * 1) COMMIT:  Every so often we need to commit the current state of the
109  *    filesystem to disk.  The journal thread is responsible for writing
110  *    all of the metadata buffers to disk.
111  *
112  * 2) CHECKPOINT: We cannot reuse a used section of the log file until all
113  *    of the data in that part of the log has been rewritten elsewhere on
114  *    the disk.  Flushing these old buffers to reclaim space in the log is
115  *    known as checkpointing, and this thread is responsible for that job.
116  */
117
118 static int kjournald2(void *arg)
119 {
120         journal_t *journal = arg;
121         transaction_t *transaction;
122
123         /*
124          * Set up an interval timer which can be used to trigger a commit wakeup
125          * after the commit interval expires
126          */
127         setup_timer(&journal->j_commit_timer, commit_timeout,
128                         (unsigned long)current);
129
130         /* Record that the journal thread is running */
131         journal->j_task = current;
132         wake_up(&journal->j_wait_done_commit);
133
134         printk(KERN_INFO "kjournald2 starting.  Commit interval %ld seconds\n",
135                         journal->j_commit_interval / HZ);
136
137         /*
138          * And now, wait forever for commit wakeup events.
139          */
140         spin_lock(&journal->j_state_lock);
141
142 loop:
143         if (journal->j_flags & JBD2_UNMOUNT)
144                 goto end_loop;
145
146         jbd_debug(1, "commit_sequence=%d, commit_request=%d\n",
147                 journal->j_commit_sequence, journal->j_commit_request);
148
149         if (journal->j_commit_sequence != journal->j_commit_request) {
150                 jbd_debug(1, "OK, requests differ\n");
151                 spin_unlock(&journal->j_state_lock);
152                 del_timer_sync(&journal->j_commit_timer);
153                 jbd2_journal_commit_transaction(journal);
154                 spin_lock(&journal->j_state_lock);
155                 goto loop;
156         }
157
158         wake_up(&journal->j_wait_done_commit);
159         if (freezing(current)) {
160                 /*
161                  * The simpler the better. Flushing journal isn't a
162                  * good idea, because that depends on threads that may
163                  * be already stopped.
164                  */
165                 jbd_debug(1, "Now suspending kjournald2\n");
166                 spin_unlock(&journal->j_state_lock);
167                 refrigerator();
168                 spin_lock(&journal->j_state_lock);
169         } else {
170                 /*
171                  * We assume on resume that commits are already there,
172                  * so we don't sleep
173                  */
174                 DEFINE_WAIT(wait);
175                 int should_sleep = 1;
176
177                 prepare_to_wait(&journal->j_wait_commit, &wait,
178                                 TASK_INTERRUPTIBLE);
179                 if (journal->j_commit_sequence != journal->j_commit_request)
180                         should_sleep = 0;
181                 transaction = journal->j_running_transaction;
182                 if (transaction && time_after_eq(jiffies,
183                                                 transaction->t_expires))
184                         should_sleep = 0;
185                 if (journal->j_flags & JBD2_UNMOUNT)
186                         should_sleep = 0;
187                 if (should_sleep) {
188                         spin_unlock(&journal->j_state_lock);
189                         schedule();
190                         spin_lock(&journal->j_state_lock);
191                 }
192                 finish_wait(&journal->j_wait_commit, &wait);
193         }
194
195         jbd_debug(1, "kjournald2 wakes\n");
196
197         /*
198          * Were we woken up by a commit wakeup event?
199          */
200         transaction = journal->j_running_transaction;
201         if (transaction && time_after_eq(jiffies, transaction->t_expires)) {
202                 journal->j_commit_request = transaction->t_tid;
203                 jbd_debug(1, "woke because of timeout\n");
204         }
205         goto loop;
206
207 end_loop:
208         spin_unlock(&journal->j_state_lock);
209         del_timer_sync(&journal->j_commit_timer);
210         journal->j_task = NULL;
211         wake_up(&journal->j_wait_done_commit);
212         jbd_debug(1, "Journal thread exiting.\n");
213         return 0;
214 }
215
216 static int jbd2_journal_start_thread(journal_t *journal)
217 {
218         struct task_struct *t;
219
220         t = kthread_run(kjournald2, journal, "kjournald2");
221         if (IS_ERR(t))
222                 return PTR_ERR(t);
223
224         wait_event(journal->j_wait_done_commit, journal->j_task != NULL);
225         return 0;
226 }
227
228 static void journal_kill_thread(journal_t *journal)
229 {
230         spin_lock(&journal->j_state_lock);
231         journal->j_flags |= JBD2_UNMOUNT;
232
233         while (journal->j_task) {
234                 wake_up(&journal->j_wait_commit);
235                 spin_unlock(&journal->j_state_lock);
236                 wait_event(journal->j_wait_done_commit, journal->j_task == NULL);
237                 spin_lock(&journal->j_state_lock);
238         }
239         spin_unlock(&journal->j_state_lock);
240 }
241
242 /*
243  * jbd2_journal_write_metadata_buffer: write a metadata buffer to the journal.
244  *
245  * Writes a metadata buffer to a given disk block.  The actual IO is not
246  * performed but a new buffer_head is constructed which labels the data
247  * to be written with the correct destination disk block.
248  *
249  * Any magic-number escaping which needs to be done will cause a
250  * copy-out here.  If the buffer happens to start with the
251  * JBD2_MAGIC_NUMBER, then we can't write it to the log directly: the
252  * magic number is only written to the log for descripter blocks.  In
253  * this case, we copy the data and replace the first word with 0, and we
254  * return a result code which indicates that this buffer needs to be
255  * marked as an escaped buffer in the corresponding log descriptor
256  * block.  The missing word can then be restored when the block is read
257  * during recovery.
258  *
259  * If the source buffer has already been modified by a new transaction
260  * since we took the last commit snapshot, we use the frozen copy of
261  * that data for IO.  If we end up using the existing buffer_head's data
262  * for the write, then we *have* to lock the buffer to prevent anyone
263  * else from using and possibly modifying it while the IO is in
264  * progress.
265  *
266  * The function returns a pointer to the buffer_heads to be used for IO.
267  *
268  * We assume that the journal has already been locked in this function.
269  *
270  * Return value:
271  *  <0: Error
272  * >=0: Finished OK
273  *
274  * On success:
275  * Bit 0 set == escape performed on the data
276  * Bit 1 set == buffer copy-out performed (kfree the data after IO)
277  */
278
279 int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
280                                   struct journal_head  *jh_in,
281                                   struct journal_head **jh_out,
282                                   unsigned long long blocknr)
283 {
284         int need_copy_out = 0;
285         int done_copy_out = 0;
286         int do_escape = 0;
287         char *mapped_data;
288         struct buffer_head *new_bh;
289         struct journal_head *new_jh;
290         struct page *new_page;
291         unsigned int new_offset;
292         struct buffer_head *bh_in = jh2bh(jh_in);
293
294         /*
295          * The buffer really shouldn't be locked: only the current committing
296          * transaction is allowed to write it, so nobody else is allowed
297          * to do any IO.
298          *
299          * akpm: except if we're journalling data, and write() output is
300          * also part of a shared mapping, and another thread has
301          * decided to launch a writepage() against this buffer.
302          */
303         J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in));
304
305         new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL);
306
307         /*
308          * If a new transaction has already done a buffer copy-out, then
309          * we use that version of the data for the commit.
310          */
311         jbd_lock_bh_state(bh_in);
312 repeat:
313         if (jh_in->b_frozen_data) {
314                 done_copy_out = 1;
315                 new_page = virt_to_page(jh_in->b_frozen_data);
316                 new_offset = offset_in_page(jh_in->b_frozen_data);
317         } else {
318                 new_page = jh2bh(jh_in)->b_page;
319                 new_offset = offset_in_page(jh2bh(jh_in)->b_data);
320         }
321
322         mapped_data = kmap_atomic(new_page, KM_USER0);
323         /*
324          * Check for escaping
325          */
326         if (*((__be32 *)(mapped_data + new_offset)) ==
327                                 cpu_to_be32(JBD2_MAGIC_NUMBER)) {
328                 need_copy_out = 1;
329                 do_escape = 1;
330         }
331         kunmap_atomic(mapped_data, KM_USER0);
332
333         /*
334          * Do we need to do a data copy?
335          */
336         if (need_copy_out && !done_copy_out) {
337                 char *tmp;
338
339                 jbd_unlock_bh_state(bh_in);
340                 tmp = jbd2_alloc(bh_in->b_size, GFP_NOFS);
341                 jbd_lock_bh_state(bh_in);
342                 if (jh_in->b_frozen_data) {
343                         jbd2_free(tmp, bh_in->b_size);
344                         goto repeat;
345                 }
346
347                 jh_in->b_frozen_data = tmp;
348                 mapped_data = kmap_atomic(new_page, KM_USER0);
349                 memcpy(tmp, mapped_data + new_offset, jh2bh(jh_in)->b_size);
350                 kunmap_atomic(mapped_data, KM_USER0);
351
352                 new_page = virt_to_page(tmp);
353                 new_offset = offset_in_page(tmp);
354                 done_copy_out = 1;
355         }
356
357         /*
358          * Did we need to do an escaping?  Now we've done all the
359          * copying, we can finally do so.
360          */
361         if (do_escape) {
362                 mapped_data = kmap_atomic(new_page, KM_USER0);
363                 *((unsigned int *)(mapped_data + new_offset)) = 0;
364                 kunmap_atomic(mapped_data, KM_USER0);
365         }
366
367         /* keep subsequent assertions sane */
368         new_bh->b_state = 0;
369         init_buffer(new_bh, NULL, NULL);
370         atomic_set(&new_bh->b_count, 1);
371         jbd_unlock_bh_state(bh_in);
372
373         new_jh = jbd2_journal_add_journal_head(new_bh); /* This sleeps */
374
375         set_bh_page(new_bh, new_page, new_offset);
376         new_jh->b_transaction = NULL;
377         new_bh->b_size = jh2bh(jh_in)->b_size;
378         new_bh->b_bdev = transaction->t_journal->j_dev;
379         new_bh->b_blocknr = blocknr;
380         set_buffer_mapped(new_bh);
381         set_buffer_dirty(new_bh);
382
383         *jh_out = new_jh;
384
385         /*
386          * The to-be-written buffer needs to get moved to the io queue,
387          * and the original buffer whose contents we are shadowing or
388          * copying is moved to the transaction's shadow queue.
389          */
390         JBUFFER_TRACE(jh_in, "file as BJ_Shadow");
391         jbd2_journal_file_buffer(jh_in, transaction, BJ_Shadow);
392         JBUFFER_TRACE(new_jh, "file as BJ_IO");
393         jbd2_journal_file_buffer(new_jh, transaction, BJ_IO);
394
395         return do_escape | (done_copy_out << 1);
396 }
397
398 /*
399  * Allocation code for the journal file.  Manage the space left in the
400  * journal, so that we can begin checkpointing when appropriate.
401  */
402
403 /*
404  * __jbd2_log_space_left: Return the number of free blocks left in the journal.
405  *
406  * Called with the journal already locked.
407  *
408  * Called under j_state_lock
409  */
410
411 int __jbd2_log_space_left(journal_t *journal)
412 {
413         int left = journal->j_free;
414
415         assert_spin_locked(&journal->j_state_lock);
416
417         /*
418          * Be pessimistic here about the number of those free blocks which
419          * might be required for log descriptor control blocks.
420          */
421
422 #define MIN_LOG_RESERVED_BLOCKS 32 /* Allow for rounding errors */
423
424         left -= MIN_LOG_RESERVED_BLOCKS;
425
426         if (left <= 0)
427                 return 0;
428         left -= (left >> 3);
429         return left;
430 }
431
432 /*
433  * Called under j_state_lock.  Returns true if a transaction was started.
434  */
435 int __jbd2_log_start_commit(journal_t *journal, tid_t target)
436 {
437         /*
438          * Are we already doing a recent enough commit?
439          */
440         if (!tid_geq(journal->j_commit_request, target)) {
441                 /*
442                  * We want a new commit: OK, mark the request and wakup the
443                  * commit thread.  We do _not_ do the commit ourselves.
444                  */
445
446                 journal->j_commit_request = target;
447                 jbd_debug(1, "JBD: requesting commit %d/%d\n",
448                           journal->j_commit_request,
449                           journal->j_commit_sequence);
450                 wake_up(&journal->j_wait_commit);
451                 return 1;
452         }
453         return 0;
454 }
455
456 int jbd2_log_start_commit(journal_t *journal, tid_t tid)
457 {
458         int ret;
459
460         spin_lock(&journal->j_state_lock);
461         ret = __jbd2_log_start_commit(journal, tid);
462         spin_unlock(&journal->j_state_lock);
463         return ret;
464 }
465
466 /*
467  * Force and wait upon a commit if the calling process is not within
468  * transaction.  This is used for forcing out undo-protected data which contains
469  * bitmaps, when the fs is running out of space.
470  *
471  * We can only force the running transaction if we don't have an active handle;
472  * otherwise, we will deadlock.
473  *
474  * Returns true if a transaction was started.
475  */
476 int jbd2_journal_force_commit_nested(journal_t *journal)
477 {
478         transaction_t *transaction = NULL;
479         tid_t tid;
480
481         spin_lock(&journal->j_state_lock);
482         if (journal->j_running_transaction && !current->journal_info) {
483                 transaction = journal->j_running_transaction;
484                 __jbd2_log_start_commit(journal, transaction->t_tid);
485         } else if (journal->j_committing_transaction)
486                 transaction = journal->j_committing_transaction;
487
488         if (!transaction) {
489                 spin_unlock(&journal->j_state_lock);
490                 return 0;       /* Nothing to retry */
491         }
492
493         tid = transaction->t_tid;
494         spin_unlock(&journal->j_state_lock);
495         jbd2_log_wait_commit(journal, tid);
496         return 1;
497 }
498
499 /*
500  * Start a commit of the current running transaction (if any).  Returns true
501  * if a transaction was started, and fills its tid in at *ptid
502  */
503 int jbd2_journal_start_commit(journal_t *journal, tid_t *ptid)
504 {
505         int ret = 0;
506
507         spin_lock(&journal->j_state_lock);
508         if (journal->j_running_transaction) {
509                 tid_t tid = journal->j_running_transaction->t_tid;
510
511                 ret = __jbd2_log_start_commit(journal, tid);
512                 if (ret && ptid)
513                         *ptid = tid;
514         } else if (journal->j_committing_transaction && ptid) {
515                 /*
516                  * If ext3_write_super() recently started a commit, then we
517                  * have to wait for completion of that transaction
518                  */
519                 *ptid = journal->j_committing_transaction->t_tid;
520                 ret = 1;
521         }
522         spin_unlock(&journal->j_state_lock);
523         return ret;
524 }
525
526 /*
527  * Wait for a specified commit to complete.
528  * The caller may not hold the journal lock.
529  */
530 int jbd2_log_wait_commit(journal_t *journal, tid_t tid)
531 {
532         int err = 0;
533
534 #ifdef CONFIG_JBD2_DEBUG
535         spin_lock(&journal->j_state_lock);
536         if (!tid_geq(journal->j_commit_request, tid)) {
537                 printk(KERN_EMERG
538                        "%s: error: j_commit_request=%d, tid=%d\n",
539                        __func__, journal->j_commit_request, tid);
540         }
541         spin_unlock(&journal->j_state_lock);
542 #endif
543         spin_lock(&journal->j_state_lock);
544         while (tid_gt(tid, journal->j_commit_sequence)) {
545                 jbd_debug(1, "JBD: want %d, j_commit_sequence=%d\n",
546                                   tid, journal->j_commit_sequence);
547                 wake_up(&journal->j_wait_commit);
548                 spin_unlock(&journal->j_state_lock);
549                 wait_event(journal->j_wait_done_commit,
550                                 !tid_gt(tid, journal->j_commit_sequence));
551                 spin_lock(&journal->j_state_lock);
552         }
553         spin_unlock(&journal->j_state_lock);
554
555         if (unlikely(is_journal_aborted(journal))) {
556                 printk(KERN_EMERG "journal commit I/O error\n");
557                 err = -EIO;
558         }
559         return err;
560 }
561
562 /*
563  * Log buffer allocation routines:
564  */
565
566 int jbd2_journal_next_log_block(journal_t *journal, unsigned long long *retp)
567 {
568         unsigned long blocknr;
569
570         spin_lock(&journal->j_state_lock);
571         J_ASSERT(journal->j_free > 1);
572
573         blocknr = journal->j_head;
574         journal->j_head++;
575         journal->j_free--;
576         if (journal->j_head == journal->j_last)
577                 journal->j_head = journal->j_first;
578         spin_unlock(&journal->j_state_lock);
579         return jbd2_journal_bmap(journal, blocknr, retp);
580 }
581
582 /*
583  * Conversion of logical to physical block numbers for the journal
584  *
585  * On external journals the journal blocks are identity-mapped, so
586  * this is a no-op.  If needed, we can use j_blk_offset - everything is
587  * ready.
588  */
589 int jbd2_journal_bmap(journal_t *journal, unsigned long blocknr,
590                  unsigned long long *retp)
591 {
592         int err = 0;
593         unsigned long long ret;
594
595         if (journal->j_inode) {
596                 ret = bmap(journal->j_inode, blocknr);
597                 if (ret)
598                         *retp = ret;
599                 else {
600                         printk(KERN_ALERT "%s: journal block not found "
601                                         "at offset %lu on %s\n",
602                                __func__, blocknr, journal->j_devname);
603                         err = -EIO;
604                         __journal_abort_soft(journal, err);
605                 }
606         } else {
607                 *retp = blocknr; /* +journal->j_blk_offset */
608         }
609         return err;
610 }
611
612 /*
613  * We play buffer_head aliasing tricks to write data/metadata blocks to
614  * the journal without copying their contents, but for journal
615  * descriptor blocks we do need to generate bona fide buffers.
616  *
617  * After the caller of jbd2_journal_get_descriptor_buffer() has finished modifying
618  * the buffer's contents they really should run flush_dcache_page(bh->b_page).
619  * But we don't bother doing that, so there will be coherency problems with
620  * mmaps of blockdevs which hold live JBD-controlled filesystems.
621  */
622 struct journal_head *jbd2_journal_get_descriptor_buffer(journal_t *journal)
623 {
624         struct buffer_head *bh;
625         unsigned long long blocknr;
626         int err;
627
628         err = jbd2_journal_next_log_block(journal, &blocknr);
629
630         if (err)
631                 return NULL;
632
633         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
634         lock_buffer(bh);
635         memset(bh->b_data, 0, journal->j_blocksize);
636         set_buffer_uptodate(bh);
637         unlock_buffer(bh);
638         BUFFER_TRACE(bh, "return this buffer");
639         return jbd2_journal_add_journal_head(bh);
640 }
641
642 struct jbd2_stats_proc_session {
643         journal_t *journal;
644         struct transaction_stats_s *stats;
645         int start;
646         int max;
647 };
648
649 static void *jbd2_history_skip_empty(struct jbd2_stats_proc_session *s,
650                                         struct transaction_stats_s *ts,
651                                         int first)
652 {
653         if (ts == s->stats + s->max)
654                 ts = s->stats;
655         if (!first && ts == s->stats + s->start)
656                 return NULL;
657         while (ts->ts_type == 0) {
658                 ts++;
659                 if (ts == s->stats + s->max)
660                         ts = s->stats;
661                 if (ts == s->stats + s->start)
662                         return NULL;
663         }
664         return ts;
665
666 }
667
668 static void *jbd2_seq_history_start(struct seq_file *seq, loff_t *pos)
669 {
670         struct jbd2_stats_proc_session *s = seq->private;
671         struct transaction_stats_s *ts;
672         int l = *pos;
673
674         if (l == 0)
675                 return SEQ_START_TOKEN;
676         ts = jbd2_history_skip_empty(s, s->stats + s->start, 1);
677         if (!ts)
678                 return NULL;
679         l--;
680         while (l) {
681                 ts = jbd2_history_skip_empty(s, ++ts, 0);
682                 if (!ts)
683                         break;
684                 l--;
685         }
686         return ts;
687 }
688
689 static void *jbd2_seq_history_next(struct seq_file *seq, void *v, loff_t *pos)
690 {
691         struct jbd2_stats_proc_session *s = seq->private;
692         struct transaction_stats_s *ts = v;
693
694         ++*pos;
695         if (v == SEQ_START_TOKEN)
696                 return jbd2_history_skip_empty(s, s->stats + s->start, 1);
697         else
698                 return jbd2_history_skip_empty(s, ++ts, 0);
699 }
700
701 static int jbd2_seq_history_show(struct seq_file *seq, void *v)
702 {
703         struct transaction_stats_s *ts = v;
704         if (v == SEQ_START_TOKEN) {
705                 seq_printf(seq, "%-4s %-5s %-5s %-5s %-5s %-5s %-5s %-6s %-5s "
706                                 "%-5s %-5s %-5s %-5s %-5s\n", "R/C", "tid",
707                                 "wait", "run", "lock", "flush", "log", "hndls",
708                                 "block", "inlog", "ctime", "write", "drop",
709                                 "close");
710                 return 0;
711         }
712         if (ts->ts_type == JBD2_STATS_RUN)
713                 seq_printf(seq, "%-4s %-5lu %-5u %-5u %-5u %-5u %-5u "
714                                 "%-6lu %-5lu %-5lu\n", "R", ts->ts_tid,
715                                 jiffies_to_msecs(ts->u.run.rs_wait),
716                                 jiffies_to_msecs(ts->u.run.rs_running),
717                                 jiffies_to_msecs(ts->u.run.rs_locked),
718                                 jiffies_to_msecs(ts->u.run.rs_flushing),
719                                 jiffies_to_msecs(ts->u.run.rs_logging),
720                                 ts->u.run.rs_handle_count,
721                                 ts->u.run.rs_blocks,
722                                 ts->u.run.rs_blocks_logged);
723         else if (ts->ts_type == JBD2_STATS_CHECKPOINT)
724                 seq_printf(seq, "%-4s %-5lu %48s %-5u %-5lu %-5lu %-5lu\n",
725                                 "C", ts->ts_tid, " ",
726                                 jiffies_to_msecs(ts->u.chp.cs_chp_time),
727                                 ts->u.chp.cs_written, ts->u.chp.cs_dropped,
728                                 ts->u.chp.cs_forced_to_close);
729         else
730                 J_ASSERT(0);
731         return 0;
732 }
733
734 static void jbd2_seq_history_stop(struct seq_file *seq, void *v)
735 {
736 }
737
738 static struct seq_operations jbd2_seq_history_ops = {
739         .start  = jbd2_seq_history_start,
740         .next   = jbd2_seq_history_next,
741         .stop   = jbd2_seq_history_stop,
742         .show   = jbd2_seq_history_show,
743 };
744
745 static int jbd2_seq_history_open(struct inode *inode, struct file *file)
746 {
747         journal_t *journal = PDE(inode)->data;
748         struct jbd2_stats_proc_session *s;
749         int rc, size;
750
751         s = kmalloc(sizeof(*s), GFP_KERNEL);
752         if (s == NULL)
753                 return -ENOMEM;
754         size = sizeof(struct transaction_stats_s) * journal->j_history_max;
755         s->stats = kmalloc(size, GFP_KERNEL);
756         if (s->stats == NULL) {
757                 kfree(s);
758                 return -ENOMEM;
759         }
760         spin_lock(&journal->j_history_lock);
761         memcpy(s->stats, journal->j_history, size);
762         s->max = journal->j_history_max;
763         s->start = journal->j_history_cur % s->max;
764         spin_unlock(&journal->j_history_lock);
765
766         rc = seq_open(file, &jbd2_seq_history_ops);
767         if (rc == 0) {
768                 struct seq_file *m = file->private_data;
769                 m->private = s;
770         } else {
771                 kfree(s->stats);
772                 kfree(s);
773         }
774         return rc;
775
776 }
777
778 static int jbd2_seq_history_release(struct inode *inode, struct file *file)
779 {
780         struct seq_file *seq = file->private_data;
781         struct jbd2_stats_proc_session *s = seq->private;
782
783         kfree(s->stats);
784         kfree(s);
785         return seq_release(inode, file);
786 }
787
788 static struct file_operations jbd2_seq_history_fops = {
789         .owner          = THIS_MODULE,
790         .open           = jbd2_seq_history_open,
791         .read           = seq_read,
792         .llseek         = seq_lseek,
793         .release        = jbd2_seq_history_release,
794 };
795
796 static void *jbd2_seq_info_start(struct seq_file *seq, loff_t *pos)
797 {
798         return *pos ? NULL : SEQ_START_TOKEN;
799 }
800
801 static void *jbd2_seq_info_next(struct seq_file *seq, void *v, loff_t *pos)
802 {
803         return NULL;
804 }
805
806 static int jbd2_seq_info_show(struct seq_file *seq, void *v)
807 {
808         struct jbd2_stats_proc_session *s = seq->private;
809
810         if (v != SEQ_START_TOKEN)
811                 return 0;
812         seq_printf(seq, "%lu transaction, each upto %u blocks\n",
813                         s->stats->ts_tid,
814                         s->journal->j_max_transaction_buffers);
815         if (s->stats->ts_tid == 0)
816                 return 0;
817         seq_printf(seq, "average: \n  %ums waiting for transaction\n",
818             jiffies_to_msecs(s->stats->u.run.rs_wait / s->stats->ts_tid));
819         seq_printf(seq, "  %ums running transaction\n",
820             jiffies_to_msecs(s->stats->u.run.rs_running / s->stats->ts_tid));
821         seq_printf(seq, "  %ums transaction was being locked\n",
822             jiffies_to_msecs(s->stats->u.run.rs_locked / s->stats->ts_tid));
823         seq_printf(seq, "  %ums flushing data (in ordered mode)\n",
824             jiffies_to_msecs(s->stats->u.run.rs_flushing / s->stats->ts_tid));
825         seq_printf(seq, "  %ums logging transaction\n",
826             jiffies_to_msecs(s->stats->u.run.rs_logging / s->stats->ts_tid));
827         seq_printf(seq, "  %lu handles per transaction\n",
828             s->stats->u.run.rs_handle_count / s->stats->ts_tid);
829         seq_printf(seq, "  %lu blocks per transaction\n",
830             s->stats->u.run.rs_blocks / s->stats->ts_tid);
831         seq_printf(seq, "  %lu logged blocks per transaction\n",
832             s->stats->u.run.rs_blocks_logged / s->stats->ts_tid);
833         return 0;
834 }
835
836 static void jbd2_seq_info_stop(struct seq_file *seq, void *v)
837 {
838 }
839
840 static struct seq_operations jbd2_seq_info_ops = {
841         .start  = jbd2_seq_info_start,
842         .next   = jbd2_seq_info_next,
843         .stop   = jbd2_seq_info_stop,
844         .show   = jbd2_seq_info_show,
845 };
846
847 static int jbd2_seq_info_open(struct inode *inode, struct file *file)
848 {
849         journal_t *journal = PDE(inode)->data;
850         struct jbd2_stats_proc_session *s;
851         int rc, size;
852
853         s = kmalloc(sizeof(*s), GFP_KERNEL);
854         if (s == NULL)
855                 return -ENOMEM;
856         size = sizeof(struct transaction_stats_s);
857         s->stats = kmalloc(size, GFP_KERNEL);
858         if (s->stats == NULL) {
859                 kfree(s);
860                 return -ENOMEM;
861         }
862         spin_lock(&journal->j_history_lock);
863         memcpy(s->stats, &journal->j_stats, size);
864         s->journal = journal;
865         spin_unlock(&journal->j_history_lock);
866
867         rc = seq_open(file, &jbd2_seq_info_ops);
868         if (rc == 0) {
869                 struct seq_file *m = file->private_data;
870                 m->private = s;
871         } else {
872                 kfree(s->stats);
873                 kfree(s);
874         }
875         return rc;
876
877 }
878
879 static int jbd2_seq_info_release(struct inode *inode, struct file *file)
880 {
881         struct seq_file *seq = file->private_data;
882         struct jbd2_stats_proc_session *s = seq->private;
883         kfree(s->stats);
884         kfree(s);
885         return seq_release(inode, file);
886 }
887
888 static struct file_operations jbd2_seq_info_fops = {
889         .owner          = THIS_MODULE,
890         .open           = jbd2_seq_info_open,
891         .read           = seq_read,
892         .llseek         = seq_lseek,
893         .release        = jbd2_seq_info_release,
894 };
895
896 static struct proc_dir_entry *proc_jbd2_stats;
897
898 static void jbd2_stats_proc_init(journal_t *journal)
899 {
900         journal->j_proc_entry = proc_mkdir(journal->j_devname, proc_jbd2_stats);
901         if (journal->j_proc_entry) {
902                 proc_create_data("history", S_IRUGO, journal->j_proc_entry,
903                                  &jbd2_seq_history_fops, journal);
904                 proc_create_data("info", S_IRUGO, journal->j_proc_entry,
905                                  &jbd2_seq_info_fops, journal);
906         }
907 }
908
909 static void jbd2_stats_proc_exit(journal_t *journal)
910 {
911         remove_proc_entry("info", journal->j_proc_entry);
912         remove_proc_entry("history", journal->j_proc_entry);
913         remove_proc_entry(journal->j_devname, proc_jbd2_stats);
914 }
915
916 static void journal_init_stats(journal_t *journal)
917 {
918         int size;
919
920         if (!proc_jbd2_stats)
921                 return;
922
923         journal->j_history_max = 100;
924         size = sizeof(struct transaction_stats_s) * journal->j_history_max;
925         journal->j_history = kzalloc(size, GFP_KERNEL);
926         if (!journal->j_history) {
927                 journal->j_history_max = 0;
928                 return;
929         }
930         spin_lock_init(&journal->j_history_lock);
931 }
932
933 /*
934  * Management for journal control blocks: functions to create and
935  * destroy journal_t structures, and to initialise and read existing
936  * journal blocks from disk.  */
937
938 /* First: create and setup a journal_t object in memory.  We initialise
939  * very few fields yet: that has to wait until we have created the
940  * journal structures from from scratch, or loaded them from disk. */
941
942 static journal_t * journal_init_common (void)
943 {
944         journal_t *journal;
945         int err;
946
947         journal = kzalloc(sizeof(*journal), GFP_KERNEL|__GFP_NOFAIL);
948         if (!journal)
949                 goto fail;
950
951         init_waitqueue_head(&journal->j_wait_transaction_locked);
952         init_waitqueue_head(&journal->j_wait_logspace);
953         init_waitqueue_head(&journal->j_wait_done_commit);
954         init_waitqueue_head(&journal->j_wait_checkpoint);
955         init_waitqueue_head(&journal->j_wait_commit);
956         init_waitqueue_head(&journal->j_wait_updates);
957         mutex_init(&journal->j_barrier);
958         mutex_init(&journal->j_checkpoint_mutex);
959         spin_lock_init(&journal->j_revoke_lock);
960         spin_lock_init(&journal->j_list_lock);
961         spin_lock_init(&journal->j_state_lock);
962
963         journal->j_commit_interval = (HZ * JBD2_DEFAULT_MAX_COMMIT_AGE);
964
965         /* The journal is marked for error until we succeed with recovery! */
966         journal->j_flags = JBD2_ABORT;
967
968         /* Set up a default-sized revoke table for the new mount. */
969         err = jbd2_journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH);
970         if (err) {
971                 kfree(journal);
972                 goto fail;
973         }
974
975         journal_init_stats(journal);
976
977         return journal;
978 fail:
979         return NULL;
980 }
981
982 /* jbd2_journal_init_dev and jbd2_journal_init_inode:
983  *
984  * Create a journal structure assigned some fixed set of disk blocks to
985  * the journal.  We don't actually touch those disk blocks yet, but we
986  * need to set up all of the mapping information to tell the journaling
987  * system where the journal blocks are.
988  *
989  */
990
991 /**
992  *  journal_t * jbd2_journal_init_dev() - creates and initialises a journal structure
993  *  @bdev: Block device on which to create the journal
994  *  @fs_dev: Device which hold journalled filesystem for this journal.
995  *  @start: Block nr Start of journal.
996  *  @len:  Length of the journal in blocks.
997  *  @blocksize: blocksize of journalling device
998  *
999  *  Returns: a newly created journal_t *
1000  *
1001  *  jbd2_journal_init_dev creates a journal which maps a fixed contiguous
1002  *  range of blocks on an arbitrary block device.
1003  *
1004  */
1005 journal_t * jbd2_journal_init_dev(struct block_device *bdev,
1006                         struct block_device *fs_dev,
1007                         unsigned long long start, int len, int blocksize)
1008 {
1009         journal_t *journal = journal_init_common();
1010         struct buffer_head *bh;
1011         char *p;
1012         int n;
1013
1014         if (!journal)
1015                 return NULL;
1016
1017         /* journal descriptor can store up to n blocks -bzzz */
1018         journal->j_blocksize = blocksize;
1019         n = journal->j_blocksize / sizeof(journal_block_tag_t);
1020         journal->j_wbufsize = n;
1021         journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
1022         if (!journal->j_wbuf) {
1023                 printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
1024                         __func__);
1025                 kfree(journal);
1026                 journal = NULL;
1027                 goto out;
1028         }
1029         journal->j_dev = bdev;
1030         journal->j_fs_dev = fs_dev;
1031         journal->j_blk_offset = start;
1032         journal->j_maxlen = len;
1033         bdevname(journal->j_dev, journal->j_devname);
1034         p = journal->j_devname;
1035         while ((p = strchr(p, '/')))
1036                 *p = '!';
1037         jbd2_stats_proc_init(journal);
1038
1039         bh = __getblk(journal->j_dev, start, journal->j_blocksize);
1040         J_ASSERT(bh != NULL);
1041         journal->j_sb_buffer = bh;
1042         journal->j_superblock = (journal_superblock_t *)bh->b_data;
1043 out:
1044         return journal;
1045 }
1046
1047 /**
1048  *  journal_t * jbd2_journal_init_inode () - creates a journal which maps to a inode.
1049  *  @inode: An inode to create the journal in
1050  *
1051  * jbd2_journal_init_inode creates a journal which maps an on-disk inode as
1052  * the journal.  The inode must exist already, must support bmap() and
1053  * must have all data blocks preallocated.
1054  */
1055 journal_t * jbd2_journal_init_inode (struct inode *inode)
1056 {
1057         struct buffer_head *bh;
1058         journal_t *journal = journal_init_common();
1059         char *p;
1060         int err;
1061         int n;
1062         unsigned long long blocknr;
1063
1064         if (!journal)
1065                 return NULL;
1066
1067         journal->j_dev = journal->j_fs_dev = inode->i_sb->s_bdev;
1068         journal->j_inode = inode;
1069         bdevname(journal->j_dev, journal->j_devname);
1070         p = journal->j_devname;
1071         while ((p = strchr(p, '/')))
1072                 *p = '!';
1073         p = journal->j_devname + strlen(journal->j_devname);
1074         sprintf(p, ":%lu", journal->j_inode->i_ino);
1075         jbd_debug(1,
1076                   "journal %p: inode %s/%ld, size %Ld, bits %d, blksize %ld\n",
1077                   journal, inode->i_sb->s_id, inode->i_ino,
1078                   (long long) inode->i_size,
1079                   inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize);
1080
1081         journal->j_maxlen = inode->i_size >> inode->i_sb->s_blocksize_bits;
1082         journal->j_blocksize = inode->i_sb->s_blocksize;
1083         jbd2_stats_proc_init(journal);
1084
1085         /* journal descriptor can store up to n blocks -bzzz */
1086         n = journal->j_blocksize / sizeof(journal_block_tag_t);
1087         journal->j_wbufsize = n;
1088         journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
1089         if (!journal->j_wbuf) {
1090                 printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
1091                         __func__);
1092                 kfree(journal);
1093                 return NULL;
1094         }
1095
1096         err = jbd2_journal_bmap(journal, 0, &blocknr);
1097         /* If that failed, give up */
1098         if (err) {
1099                 printk(KERN_ERR "%s: Cannnot locate journal superblock\n",
1100                        __func__);
1101                 kfree(journal);
1102                 return NULL;
1103         }
1104
1105         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
1106         J_ASSERT(bh != NULL);
1107         journal->j_sb_buffer = bh;
1108         journal->j_superblock = (journal_superblock_t *)bh->b_data;
1109
1110         return journal;
1111 }
1112
1113 /*
1114  * If the journal init or create aborts, we need to mark the journal
1115  * superblock as being NULL to prevent the journal destroy from writing
1116  * back a bogus superblock.
1117  */
1118 static void journal_fail_superblock (journal_t *journal)
1119 {
1120         struct buffer_head *bh = journal->j_sb_buffer;
1121         brelse(bh);
1122         journal->j_sb_buffer = NULL;
1123 }
1124
1125 /*
1126  * Given a journal_t structure, initialise the various fields for
1127  * startup of a new journaling session.  We use this both when creating
1128  * a journal, and after recovering an old journal to reset it for
1129  * subsequent use.
1130  */
1131
1132 static int journal_reset(journal_t *journal)
1133 {
1134         journal_superblock_t *sb = journal->j_superblock;
1135         unsigned long long first, last;
1136
1137         first = be32_to_cpu(sb->s_first);
1138         last = be32_to_cpu(sb->s_maxlen);
1139
1140         journal->j_first = first;
1141         journal->j_last = last;
1142
1143         journal->j_head = first;
1144         journal->j_tail = first;
1145         journal->j_free = last - first;
1146
1147         journal->j_tail_sequence = journal->j_transaction_sequence;
1148         journal->j_commit_sequence = journal->j_transaction_sequence - 1;
1149         journal->j_commit_request = journal->j_commit_sequence;
1150
1151         journal->j_max_transaction_buffers = journal->j_maxlen / 4;
1152
1153         /* Add the dynamic fields and write it to disk. */
1154         jbd2_journal_update_superblock(journal, 1);
1155         return jbd2_journal_start_thread(journal);
1156 }
1157
1158 /**
1159  * int jbd2_journal_create() - Initialise the new journal file
1160  * @journal: Journal to create. This structure must have been initialised
1161  *
1162  * Given a journal_t structure which tells us which disk blocks we can
1163  * use, create a new journal superblock and initialise all of the
1164  * journal fields from scratch.
1165  **/
1166 int jbd2_journal_create(journal_t *journal)
1167 {
1168         unsigned long long blocknr;
1169         struct buffer_head *bh;
1170         journal_superblock_t *sb;
1171         int i, err;
1172
1173         if (journal->j_maxlen < JBD2_MIN_JOURNAL_BLOCKS) {
1174                 printk (KERN_ERR "Journal length (%d blocks) too short.\n",
1175                         journal->j_maxlen);
1176                 journal_fail_superblock(journal);
1177                 return -EINVAL;
1178         }
1179
1180         if (journal->j_inode == NULL) {
1181                 /*
1182                  * We don't know what block to start at!
1183                  */
1184                 printk(KERN_EMERG
1185                        "%s: creation of journal on external device!\n",
1186                        __func__);
1187                 BUG();
1188         }
1189
1190         /* Zero out the entire journal on disk.  We cannot afford to
1191            have any blocks on disk beginning with JBD2_MAGIC_NUMBER. */
1192         jbd_debug(1, "JBD: Zeroing out journal blocks...\n");
1193         for (i = 0; i < journal->j_maxlen; i++) {
1194                 err = jbd2_journal_bmap(journal, i, &blocknr);
1195                 if (err)
1196                         return err;
1197                 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
1198                 lock_buffer(bh);
1199                 memset (bh->b_data, 0, journal->j_blocksize);
1200                 BUFFER_TRACE(bh, "marking dirty");
1201                 mark_buffer_dirty(bh);
1202                 BUFFER_TRACE(bh, "marking uptodate");
1203                 set_buffer_uptodate(bh);
1204                 unlock_buffer(bh);
1205                 __brelse(bh);
1206         }
1207
1208         sync_blockdev(journal->j_dev);
1209         jbd_debug(1, "JBD: journal cleared.\n");
1210
1211         /* OK, fill in the initial static fields in the new superblock */
1212         sb = journal->j_superblock;
1213
1214         sb->s_header.h_magic     = cpu_to_be32(JBD2_MAGIC_NUMBER);
1215         sb->s_header.h_blocktype = cpu_to_be32(JBD2_SUPERBLOCK_V2);
1216
1217         sb->s_blocksize = cpu_to_be32(journal->j_blocksize);
1218         sb->s_maxlen    = cpu_to_be32(journal->j_maxlen);
1219         sb->s_first     = cpu_to_be32(1);
1220
1221         journal->j_transaction_sequence = 1;
1222
1223         journal->j_flags &= ~JBD2_ABORT;
1224         journal->j_format_version = 2;
1225
1226         return journal_reset(journal);
1227 }
1228
1229 /**
1230  * void jbd2_journal_update_superblock() - Update journal sb on disk.
1231  * @journal: The journal to update.
1232  * @wait: Set to '0' if you don't want to wait for IO completion.
1233  *
1234  * Update a journal's dynamic superblock fields and write it to disk,
1235  * optionally waiting for the IO to complete.
1236  */
1237 void jbd2_journal_update_superblock(journal_t *journal, int wait)
1238 {
1239         journal_superblock_t *sb = journal->j_superblock;
1240         struct buffer_head *bh = journal->j_sb_buffer;
1241
1242         /*
1243          * As a special case, if the on-disk copy is already marked as needing
1244          * no recovery (s_start == 0) and there are no outstanding transactions
1245          * in the filesystem, then we can safely defer the superblock update
1246          * until the next commit by setting JBD2_FLUSHED.  This avoids
1247          * attempting a write to a potential-readonly device.
1248          */
1249         if (sb->s_start == 0 && journal->j_tail_sequence ==
1250                                 journal->j_transaction_sequence) {
1251                 jbd_debug(1,"JBD: Skipping superblock update on recovered sb "
1252                         "(start %ld, seq %d, errno %d)\n",
1253                         journal->j_tail, journal->j_tail_sequence,
1254                         journal->j_errno);
1255                 goto out;
1256         }
1257
1258         spin_lock(&journal->j_state_lock);
1259         jbd_debug(1,"JBD: updating superblock (start %ld, seq %d, errno %d)\n",
1260                   journal->j_tail, journal->j_tail_sequence, journal->j_errno);
1261
1262         sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
1263         sb->s_start    = cpu_to_be32(journal->j_tail);
1264         sb->s_errno    = cpu_to_be32(journal->j_errno);
1265         spin_unlock(&journal->j_state_lock);
1266
1267         BUFFER_TRACE(bh, "marking dirty");
1268         mark_buffer_dirty(bh);
1269         if (wait)
1270                 sync_dirty_buffer(bh);
1271         else
1272                 ll_rw_block(SWRITE, 1, &bh);
1273
1274 out:
1275         /* If we have just flushed the log (by marking s_start==0), then
1276          * any future commit will have to be careful to update the
1277          * superblock again to re-record the true start of the log. */
1278
1279         spin_lock(&journal->j_state_lock);
1280         if (sb->s_start)
1281                 journal->j_flags &= ~JBD2_FLUSHED;
1282         else
1283                 journal->j_flags |= JBD2_FLUSHED;
1284         spin_unlock(&journal->j_state_lock);
1285 }
1286
1287 /*
1288  * Read the superblock for a given journal, performing initial
1289  * validation of the format.
1290  */
1291
1292 static int journal_get_superblock(journal_t *journal)
1293 {
1294         struct buffer_head *bh;
1295         journal_superblock_t *sb;
1296         int err = -EIO;
1297
1298         bh = journal->j_sb_buffer;
1299
1300         J_ASSERT(bh != NULL);
1301         if (!buffer_uptodate(bh)) {
1302                 ll_rw_block(READ, 1, &bh);
1303                 wait_on_buffer(bh);
1304                 if (!buffer_uptodate(bh)) {
1305                         printk (KERN_ERR
1306                                 "JBD: IO error reading journal superblock\n");
1307                         goto out;
1308                 }
1309         }
1310
1311         sb = journal->j_superblock;
1312
1313         err = -EINVAL;
1314
1315         if (sb->s_header.h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER) ||
1316             sb->s_blocksize != cpu_to_be32(journal->j_blocksize)) {
1317                 printk(KERN_WARNING "JBD: no valid journal superblock found\n");
1318                 goto out;
1319         }
1320
1321         switch(be32_to_cpu(sb->s_header.h_blocktype)) {
1322         case JBD2_SUPERBLOCK_V1:
1323                 journal->j_format_version = 1;
1324                 break;
1325         case JBD2_SUPERBLOCK_V2:
1326                 journal->j_format_version = 2;
1327                 break;
1328         default:
1329                 printk(KERN_WARNING "JBD: unrecognised superblock format ID\n");
1330                 goto out;
1331         }
1332
1333         if (be32_to_cpu(sb->s_maxlen) < journal->j_maxlen)
1334                 journal->j_maxlen = be32_to_cpu(sb->s_maxlen);
1335         else if (be32_to_cpu(sb->s_maxlen) > journal->j_maxlen) {
1336                 printk (KERN_WARNING "JBD: journal file too short\n");
1337                 goto out;
1338         }
1339
1340         return 0;
1341
1342 out:
1343         journal_fail_superblock(journal);
1344         return err;
1345 }
1346
1347 /*
1348  * Load the on-disk journal superblock and read the key fields into the
1349  * journal_t.
1350  */
1351
1352 static int load_superblock(journal_t *journal)
1353 {
1354         int err;
1355         journal_superblock_t *sb;
1356
1357         err = journal_get_superblock(journal);
1358         if (err)
1359                 return err;
1360
1361         sb = journal->j_superblock;
1362
1363         journal->j_tail_sequence = be32_to_cpu(sb->s_sequence);
1364         journal->j_tail = be32_to_cpu(sb->s_start);
1365         journal->j_first = be32_to_cpu(sb->s_first);
1366         journal->j_last = be32_to_cpu(sb->s_maxlen);
1367         journal->j_errno = be32_to_cpu(sb->s_errno);
1368
1369         return 0;
1370 }
1371
1372
1373 /**
1374  * int jbd2_journal_load() - Read journal from disk.
1375  * @journal: Journal to act on.
1376  *
1377  * Given a journal_t structure which tells us which disk blocks contain
1378  * a journal, read the journal from disk to initialise the in-memory
1379  * structures.
1380  */
1381 int jbd2_journal_load(journal_t *journal)
1382 {
1383         int err;
1384         journal_superblock_t *sb;
1385
1386         err = load_superblock(journal);
1387         if (err)
1388                 return err;
1389
1390         sb = journal->j_superblock;
1391         /* If this is a V2 superblock, then we have to check the
1392          * features flags on it. */
1393
1394         if (journal->j_format_version >= 2) {
1395                 if ((sb->s_feature_ro_compat &
1396                      ~cpu_to_be32(JBD2_KNOWN_ROCOMPAT_FEATURES)) ||
1397                     (sb->s_feature_incompat &
1398                      ~cpu_to_be32(JBD2_KNOWN_INCOMPAT_FEATURES))) {
1399                         printk (KERN_WARNING
1400                                 "JBD: Unrecognised features on journal\n");
1401                         return -EINVAL;
1402                 }
1403         }
1404
1405         /* Let the recovery code check whether it needs to recover any
1406          * data from the journal. */
1407         if (jbd2_journal_recover(journal))
1408                 goto recovery_error;
1409
1410         /* OK, we've finished with the dynamic journal bits:
1411          * reinitialise the dynamic contents of the superblock in memory
1412          * and reset them on disk. */
1413         if (journal_reset(journal))
1414                 goto recovery_error;
1415
1416         journal->j_flags &= ~JBD2_ABORT;
1417         journal->j_flags |= JBD2_LOADED;
1418         return 0;
1419
1420 recovery_error:
1421         printk (KERN_WARNING "JBD: recovery failed\n");
1422         return -EIO;
1423 }
1424
1425 /**
1426  * void jbd2_journal_destroy() - Release a journal_t structure.
1427  * @journal: Journal to act on.
1428  *
1429  * Release a journal_t structure once it is no longer in use by the
1430  * journaled object.
1431  */
1432 void jbd2_journal_destroy(journal_t *journal)
1433 {
1434         /* Wait for the commit thread to wake up and die. */
1435         journal_kill_thread(journal);
1436
1437         /* Force a final log commit */
1438         if (journal->j_running_transaction)
1439                 jbd2_journal_commit_transaction(journal);
1440
1441         /* Force any old transactions to disk */
1442
1443         /* Totally anal locking here... */
1444         spin_lock(&journal->j_list_lock);
1445         while (journal->j_checkpoint_transactions != NULL) {
1446                 spin_unlock(&journal->j_list_lock);
1447                 jbd2_log_do_checkpoint(journal);
1448                 spin_lock(&journal->j_list_lock);
1449         }
1450
1451         J_ASSERT(journal->j_running_transaction == NULL);
1452         J_ASSERT(journal->j_committing_transaction == NULL);
1453         J_ASSERT(journal->j_checkpoint_transactions == NULL);
1454         spin_unlock(&journal->j_list_lock);
1455
1456         /* We can now mark the journal as empty. */
1457         journal->j_tail = 0;
1458         journal->j_tail_sequence = ++journal->j_transaction_sequence;
1459         if (journal->j_sb_buffer) {
1460                 jbd2_journal_update_superblock(journal, 1);
1461                 brelse(journal->j_sb_buffer);
1462         }
1463
1464         if (journal->j_proc_entry)
1465                 jbd2_stats_proc_exit(journal);
1466         if (journal->j_inode)
1467                 iput(journal->j_inode);
1468         if (journal->j_revoke)
1469                 jbd2_journal_destroy_revoke(journal);
1470         kfree(journal->j_wbuf);
1471         kfree(journal);
1472 }
1473
1474
1475 /**
1476  *int jbd2_journal_check_used_features () - Check if features specified are used.
1477  * @journal: Journal to check.
1478  * @compat: bitmask of compatible features
1479  * @ro: bitmask of features that force read-only mount
1480  * @incompat: bitmask of incompatible features
1481  *
1482  * Check whether the journal uses all of a given set of
1483  * features.  Return true (non-zero) if it does.
1484  **/
1485
1486 int jbd2_journal_check_used_features (journal_t *journal, unsigned long compat,
1487                                  unsigned long ro, unsigned long incompat)
1488 {
1489         journal_superblock_t *sb;
1490
1491         if (!compat && !ro && !incompat)
1492                 return 1;
1493         if (journal->j_format_version == 1)
1494                 return 0;
1495
1496         sb = journal->j_superblock;
1497
1498         if (((be32_to_cpu(sb->s_feature_compat) & compat) == compat) &&
1499             ((be32_to_cpu(sb->s_feature_ro_compat) & ro) == ro) &&
1500             ((be32_to_cpu(sb->s_feature_incompat) & incompat) == incompat))
1501                 return 1;
1502
1503         return 0;
1504 }
1505
1506 /**
1507  * int jbd2_journal_check_available_features() - Check feature set in journalling layer
1508  * @journal: Journal to check.
1509  * @compat: bitmask of compatible features
1510  * @ro: bitmask of features that force read-only mount
1511  * @incompat: bitmask of incompatible features
1512  *
1513  * Check whether the journaling code supports the use of
1514  * all of a given set of features on this journal.  Return true
1515  * (non-zero) if it can. */
1516
1517 int jbd2_journal_check_available_features (journal_t *journal, unsigned long compat,
1518                                       unsigned long ro, unsigned long incompat)
1519 {
1520         journal_superblock_t *sb;
1521
1522         if (!compat && !ro && !incompat)
1523                 return 1;
1524
1525         sb = journal->j_superblock;
1526
1527         /* We can support any known requested features iff the
1528          * superblock is in version 2.  Otherwise we fail to support any
1529          * extended sb features. */
1530
1531         if (journal->j_format_version != 2)
1532                 return 0;
1533
1534         if ((compat   & JBD2_KNOWN_COMPAT_FEATURES) == compat &&
1535             (ro       & JBD2_KNOWN_ROCOMPAT_FEATURES) == ro &&
1536             (incompat & JBD2_KNOWN_INCOMPAT_FEATURES) == incompat)
1537                 return 1;
1538
1539         return 0;
1540 }
1541
1542 /**
1543  * int jbd2_journal_set_features () - Mark a given journal feature in the superblock
1544  * @journal: Journal to act on.
1545  * @compat: bitmask of compatible features
1546  * @ro: bitmask of features that force read-only mount
1547  * @incompat: bitmask of incompatible features
1548  *
1549  * Mark a given journal feature as present on the
1550  * superblock.  Returns true if the requested features could be set.
1551  *
1552  */
1553
1554 int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
1555                           unsigned long ro, unsigned long incompat)
1556 {
1557         journal_superblock_t *sb;
1558
1559         if (jbd2_journal_check_used_features(journal, compat, ro, incompat))
1560                 return 1;
1561
1562         if (!jbd2_journal_check_available_features(journal, compat, ro, incompat))
1563                 return 0;
1564
1565         jbd_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n",
1566                   compat, ro, incompat);
1567
1568         sb = journal->j_superblock;
1569
1570         sb->s_feature_compat    |= cpu_to_be32(compat);
1571         sb->s_feature_ro_compat |= cpu_to_be32(ro);
1572         sb->s_feature_incompat  |= cpu_to_be32(incompat);
1573
1574         return 1;
1575 }
1576
1577 /*
1578  * jbd2_journal_clear_features () - Clear a given journal feature in the
1579  *                                  superblock
1580  * @journal: Journal to act on.
1581  * @compat: bitmask of compatible features
1582  * @ro: bitmask of features that force read-only mount
1583  * @incompat: bitmask of incompatible features
1584  *
1585  * Clear a given journal feature as present on the
1586  * superblock.
1587  */
1588 void jbd2_journal_clear_features(journal_t *journal, unsigned long compat,
1589                                 unsigned long ro, unsigned long incompat)
1590 {
1591         journal_superblock_t *sb;
1592
1593         jbd_debug(1, "Clear features 0x%lx/0x%lx/0x%lx\n",
1594                   compat, ro, incompat);
1595
1596         sb = journal->j_superblock;
1597
1598         sb->s_feature_compat    &= ~cpu_to_be32(compat);
1599         sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
1600         sb->s_feature_incompat  &= ~cpu_to_be32(incompat);
1601 }
1602 EXPORT_SYMBOL(jbd2_journal_clear_features);
1603
1604 /**
1605  * int jbd2_journal_update_format () - Update on-disk journal structure.
1606  * @journal: Journal to act on.
1607  *
1608  * Given an initialised but unloaded journal struct, poke about in the
1609  * on-disk structure to update it to the most recent supported version.
1610  */
1611 int jbd2_journal_update_format (journal_t *journal)
1612 {
1613         journal_superblock_t *sb;
1614         int err;
1615
1616         err = journal_get_superblock(journal);
1617         if (err)
1618                 return err;
1619
1620         sb = journal->j_superblock;
1621
1622         switch (be32_to_cpu(sb->s_header.h_blocktype)) {
1623         case JBD2_SUPERBLOCK_V2:
1624                 return 0;
1625         case JBD2_SUPERBLOCK_V1:
1626                 return journal_convert_superblock_v1(journal, sb);
1627         default:
1628                 break;
1629         }
1630         return -EINVAL;
1631 }
1632
1633 static int journal_convert_superblock_v1(journal_t *journal,
1634                                          journal_superblock_t *sb)
1635 {
1636         int offset, blocksize;
1637         struct buffer_head *bh;
1638
1639         printk(KERN_WARNING
1640                 "JBD: Converting superblock from version 1 to 2.\n");
1641
1642         /* Pre-initialise new fields to zero */
1643         offset = ((char *) &(sb->s_feature_compat)) - ((char *) sb);
1644         blocksize = be32_to_cpu(sb->s_blocksize);
1645         memset(&sb->s_feature_compat, 0, blocksize-offset);
1646
1647         sb->s_nr_users = cpu_to_be32(1);
1648         sb->s_header.h_blocktype = cpu_to_be32(JBD2_SUPERBLOCK_V2);
1649         journal->j_format_version = 2;
1650
1651         bh = journal->j_sb_buffer;
1652         BUFFER_TRACE(bh, "marking dirty");
1653         mark_buffer_dirty(bh);
1654         sync_dirty_buffer(bh);
1655         return 0;
1656 }
1657
1658
1659 /**
1660  * int jbd2_journal_flush () - Flush journal
1661  * @journal: Journal to act on.
1662  *
1663  * Flush all data for a given journal to disk and empty the journal.
1664  * Filesystems can use this when remounting readonly to ensure that
1665  * recovery does not need to happen on remount.
1666  */
1667
1668 int jbd2_journal_flush(journal_t *journal)
1669 {
1670         int err = 0;
1671         transaction_t *transaction = NULL;
1672         unsigned long old_tail;
1673
1674         spin_lock(&journal->j_state_lock);
1675
1676         /* Force everything buffered to the log... */
1677         if (journal->j_running_transaction) {
1678                 transaction = journal->j_running_transaction;
1679                 __jbd2_log_start_commit(journal, transaction->t_tid);
1680         } else if (journal->j_committing_transaction)
1681                 transaction = journal->j_committing_transaction;
1682
1683         /* Wait for the log commit to complete... */
1684         if (transaction) {
1685                 tid_t tid = transaction->t_tid;
1686
1687                 spin_unlock(&journal->j_state_lock);
1688                 jbd2_log_wait_commit(journal, tid);
1689         } else {
1690                 spin_unlock(&journal->j_state_lock);
1691         }
1692
1693         /* ...and flush everything in the log out to disk. */
1694         spin_lock(&journal->j_list_lock);
1695         while (!err && journal->j_checkpoint_transactions != NULL) {
1696                 spin_unlock(&journal->j_list_lock);
1697                 err = jbd2_log_do_checkpoint(journal);
1698                 spin_lock(&journal->j_list_lock);
1699         }
1700         spin_unlock(&journal->j_list_lock);
1701         jbd2_cleanup_journal_tail(journal);
1702
1703         /* Finally, mark the journal as really needing no recovery.
1704          * This sets s_start==0 in the underlying superblock, which is
1705          * the magic code for a fully-recovered superblock.  Any future
1706          * commits of data to the journal will restore the current
1707          * s_start value. */
1708         spin_lock(&journal->j_state_lock);
1709         old_tail = journal->j_tail;
1710         journal->j_tail = 0;
1711         spin_unlock(&journal->j_state_lock);
1712         jbd2_journal_update_superblock(journal, 1);
1713         spin_lock(&journal->j_state_lock);
1714         journal->j_tail = old_tail;
1715
1716         J_ASSERT(!journal->j_running_transaction);
1717         J_ASSERT(!journal->j_committing_transaction);
1718         J_ASSERT(!journal->j_checkpoint_transactions);
1719         J_ASSERT(journal->j_head == journal->j_tail);
1720         J_ASSERT(journal->j_tail_sequence == journal->j_transaction_sequence);
1721         spin_unlock(&journal->j_state_lock);
1722         return err;
1723 }
1724
1725 /**
1726  * int jbd2_journal_wipe() - Wipe journal contents
1727  * @journal: Journal to act on.
1728  * @write: flag (see below)
1729  *
1730  * Wipe out all of the contents of a journal, safely.  This will produce
1731  * a warning if the journal contains any valid recovery information.
1732  * Must be called between journal_init_*() and jbd2_journal_load().
1733  *
1734  * If 'write' is non-zero, then we wipe out the journal on disk; otherwise
1735  * we merely suppress recovery.
1736  */
1737
1738 int jbd2_journal_wipe(journal_t *journal, int write)
1739 {
1740         journal_superblock_t *sb;
1741         int err = 0;
1742
1743         J_ASSERT (!(journal->j_flags & JBD2_LOADED));
1744
1745         err = load_superblock(journal);
1746         if (err)
1747                 return err;
1748
1749         sb = journal->j_superblock;
1750
1751         if (!journal->j_tail)
1752                 goto no_recovery;
1753
1754         printk (KERN_WARNING "JBD: %s recovery information on journal\n",
1755                 write ? "Clearing" : "Ignoring");
1756
1757         err = jbd2_journal_skip_recovery(journal);
1758         if (write)
1759                 jbd2_journal_update_superblock(journal, 1);
1760
1761  no_recovery:
1762         return err;
1763 }
1764
1765 /*
1766  * Journal abort has very specific semantics, which we describe
1767  * for journal abort.
1768  *
1769  * Two internal function, which provide abort to te jbd layer
1770  * itself are here.
1771  */
1772
1773 /*
1774  * Quick version for internal journal use (doesn't lock the journal).
1775  * Aborts hard --- we mark the abort as occurred, but do _nothing_ else,
1776  * and don't attempt to make any other journal updates.
1777  */
1778 void __jbd2_journal_abort_hard(journal_t *journal)
1779 {
1780         transaction_t *transaction;
1781
1782         if (journal->j_flags & JBD2_ABORT)
1783                 return;
1784
1785         printk(KERN_ERR "Aborting journal on device %s.\n",
1786                journal->j_devname);
1787
1788         spin_lock(&journal->j_state_lock);
1789         journal->j_flags |= JBD2_ABORT;
1790         transaction = journal->j_running_transaction;
1791         if (transaction)
1792                 __jbd2_log_start_commit(journal, transaction->t_tid);
1793         spin_unlock(&journal->j_state_lock);
1794 }
1795
1796 /* Soft abort: record the abort error status in the journal superblock,
1797  * but don't do any other IO. */
1798 static void __journal_abort_soft (journal_t *journal, int errno)
1799 {
1800         if (journal->j_flags & JBD2_ABORT)
1801                 return;
1802
1803         if (!journal->j_errno)
1804                 journal->j_errno = errno;
1805
1806         __jbd2_journal_abort_hard(journal);
1807
1808         if (errno)
1809                 jbd2_journal_update_superblock(journal, 1);
1810 }
1811
1812 /**
1813  * void jbd2_journal_abort () - Shutdown the journal immediately.
1814  * @journal: the journal to shutdown.
1815  * @errno:   an error number to record in the journal indicating
1816  *           the reason for the shutdown.
1817  *
1818  * Perform a complete, immediate shutdown of the ENTIRE
1819  * journal (not of a single transaction).  This operation cannot be
1820  * undone without closing and reopening the journal.
1821  *
1822  * The jbd2_journal_abort function is intended to support higher level error
1823  * recovery mechanisms such as the ext2/ext3 remount-readonly error
1824  * mode.
1825  *
1826  * Journal abort has very specific semantics.  Any existing dirty,
1827  * unjournaled buffers in the main filesystem will still be written to
1828  * disk by bdflush, but the journaling mechanism will be suspended
1829  * immediately and no further transaction commits will be honoured.
1830  *
1831  * Any dirty, journaled buffers will be written back to disk without
1832  * hitting the journal.  Atomicity cannot be guaranteed on an aborted
1833  * filesystem, but we _do_ attempt to leave as much data as possible
1834  * behind for fsck to use for cleanup.
1835  *
1836  * Any attempt to get a new transaction handle on a journal which is in
1837  * ABORT state will just result in an -EROFS error return.  A
1838  * jbd2_journal_stop on an existing handle will return -EIO if we have
1839  * entered abort state during the update.
1840  *
1841  * Recursive transactions are not disturbed by journal abort until the
1842  * final jbd2_journal_stop, which will receive the -EIO error.
1843  *
1844  * Finally, the jbd2_journal_abort call allows the caller to supply an errno
1845  * which will be recorded (if possible) in the journal superblock.  This
1846  * allows a client to record failure conditions in the middle of a
1847  * transaction without having to complete the transaction to record the
1848  * failure to disk.  ext3_error, for example, now uses this
1849  * functionality.
1850  *
1851  * Errors which originate from within the journaling layer will NOT
1852  * supply an errno; a null errno implies that absolutely no further
1853  * writes are done to the journal (unless there are any already in
1854  * progress).
1855  *
1856  */
1857
1858 void jbd2_journal_abort(journal_t *journal, int errno)
1859 {
1860         __journal_abort_soft(journal, errno);
1861 }
1862
1863 /**
1864  * int jbd2_journal_errno () - returns the journal's error state.
1865  * @journal: journal to examine.
1866  *
1867  * This is the errno numbet set with jbd2_journal_abort(), the last
1868  * time the journal was mounted - if the journal was stopped
1869  * without calling abort this will be 0.
1870  *
1871  * If the journal has been aborted on this mount time -EROFS will
1872  * be returned.
1873  */
1874 int jbd2_journal_errno(journal_t *journal)
1875 {
1876         int err;
1877
1878         spin_lock(&journal->j_state_lock);
1879         if (journal->j_flags & JBD2_ABORT)
1880                 err = -EROFS;
1881         else
1882                 err = journal->j_errno;
1883         spin_unlock(&journal->j_state_lock);
1884         return err;
1885 }
1886
1887 /**
1888  * int jbd2_journal_clear_err () - clears the journal's error state
1889  * @journal: journal to act on.
1890  *
1891  * An error must be cleared or Acked to take a FS out of readonly
1892  * mode.
1893  */
1894 int jbd2_journal_clear_err(journal_t *journal)
1895 {
1896         int err = 0;
1897
1898         spin_lock(&journal->j_state_lock);
1899         if (journal->j_flags & JBD2_ABORT)
1900                 err = -EROFS;
1901         else
1902                 journal->j_errno = 0;
1903         spin_unlock(&journal->j_state_lock);
1904         return err;
1905 }
1906
1907 /**
1908  * void jbd2_journal_ack_err() - Ack journal err.
1909  * @journal: journal to act on.
1910  *
1911  * An error must be cleared or Acked to take a FS out of readonly
1912  * mode.
1913  */
1914 void jbd2_journal_ack_err(journal_t *journal)
1915 {
1916         spin_lock(&journal->j_state_lock);
1917         if (journal->j_errno)
1918                 journal->j_flags |= JBD2_ACK_ERR;
1919         spin_unlock(&journal->j_state_lock);
1920 }
1921
1922 int jbd2_journal_blocks_per_page(struct inode *inode)
1923 {
1924         return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
1925 }
1926
1927 /*
1928  * helper functions to deal with 32 or 64bit block numbers.
1929  */
1930 size_t journal_tag_bytes(journal_t *journal)
1931 {
1932         if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
1933                 return JBD2_TAG_SIZE64;
1934         else
1935                 return JBD2_TAG_SIZE32;
1936 }
1937
1938 /*
1939  * Journal_head storage management
1940  */
1941 static struct kmem_cache *jbd2_journal_head_cache;
1942 #ifdef CONFIG_JBD2_DEBUG
1943 static atomic_t nr_journal_heads = ATOMIC_INIT(0);
1944 #endif
1945
1946 static int journal_init_jbd2_journal_head_cache(void)
1947 {
1948         int retval;
1949
1950         J_ASSERT(jbd2_journal_head_cache == NULL);
1951         jbd2_journal_head_cache = kmem_cache_create("jbd2_journal_head",
1952                                 sizeof(struct journal_head),
1953                                 0,              /* offset */
1954                                 SLAB_TEMPORARY, /* flags */
1955                                 NULL);          /* ctor */
1956         retval = 0;
1957         if (!jbd2_journal_head_cache) {
1958                 retval = -ENOMEM;
1959                 printk(KERN_EMERG "JBD: no memory for journal_head cache\n");
1960         }
1961         return retval;
1962 }
1963
1964 static void jbd2_journal_destroy_jbd2_journal_head_cache(void)
1965 {
1966         if (jbd2_journal_head_cache) {
1967                 kmem_cache_destroy(jbd2_journal_head_cache);
1968                 jbd2_journal_head_cache = NULL;
1969         }
1970 }
1971
1972 /*
1973  * journal_head splicing and dicing
1974  */
1975 static struct journal_head *journal_alloc_journal_head(void)
1976 {
1977         struct journal_head *ret;
1978         static unsigned long last_warning;
1979
1980 #ifdef CONFIG_JBD2_DEBUG
1981         atomic_inc(&nr_journal_heads);
1982 #endif
1983         ret = kmem_cache_alloc(jbd2_journal_head_cache, GFP_NOFS);
1984         if (!ret) {
1985                 jbd_debug(1, "out of memory for journal_head\n");
1986                 if (time_after(jiffies, last_warning + 5*HZ)) {
1987                         printk(KERN_NOTICE "ENOMEM in %s, retrying.\n",
1988                                __func__);
1989                         last_warning = jiffies;
1990                 }
1991                 while (!ret) {
1992                         yield();
1993                         ret = kmem_cache_alloc(jbd2_journal_head_cache, GFP_NOFS);
1994                 }
1995         }
1996         return ret;
1997 }
1998
1999 static void journal_free_journal_head(struct journal_head *jh)
2000 {
2001 #ifdef CONFIG_JBD2_DEBUG
2002         atomic_dec(&nr_journal_heads);
2003         memset(jh, JBD2_POISON_FREE, sizeof(*jh));
2004 #endif
2005         kmem_cache_free(jbd2_journal_head_cache, jh);
2006 }
2007
2008 /*
2009  * A journal_head is attached to a buffer_head whenever JBD has an
2010  * interest in the buffer.
2011  *
2012  * Whenever a buffer has an attached journal_head, its ->b_state:BH_JBD bit
2013  * is set.  This bit is tested in core kernel code where we need to take
2014  * JBD-specific actions.  Testing the zeroness of ->b_private is not reliable
2015  * there.
2016  *
2017  * When a buffer has its BH_JBD bit set, its ->b_count is elevated by one.
2018  *
2019  * When a buffer has its BH_JBD bit set it is immune from being released by
2020  * core kernel code, mainly via ->b_count.
2021  *
2022  * A journal_head may be detached from its buffer_head when the journal_head's
2023  * b_transaction, b_cp_transaction and b_next_transaction pointers are NULL.
2024  * Various places in JBD call jbd2_journal_remove_journal_head() to indicate that the
2025  * journal_head can be dropped if needed.
2026  *
2027  * Various places in the kernel want to attach a journal_head to a buffer_head
2028  * _before_ attaching the journal_head to a transaction.  To protect the
2029  * journal_head in this situation, jbd2_journal_add_journal_head elevates the
2030  * journal_head's b_jcount refcount by one.  The caller must call
2031  * jbd2_journal_put_journal_head() to undo this.
2032  *
2033  * So the typical usage would be:
2034  *
2035  *      (Attach a journal_head if needed.  Increments b_jcount)
2036  *      struct journal_head *jh = jbd2_journal_add_journal_head(bh);
2037  *      ...
2038  *      jh->b_transaction = xxx;
2039  *      jbd2_journal_put_journal_head(jh);
2040  *
2041  * Now, the journal_head's b_jcount is zero, but it is safe from being released
2042  * because it has a non-zero b_transaction.
2043  */
2044
2045 /*
2046  * Give a buffer_head a journal_head.
2047  *
2048  * Doesn't need the journal lock.
2049  * May sleep.
2050  */
2051 struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh)
2052 {
2053         struct journal_head *jh;
2054         struct journal_head *new_jh = NULL;
2055
2056 repeat:
2057         if (!buffer_jbd(bh)) {
2058                 new_jh = journal_alloc_journal_head();
2059                 memset(new_jh, 0, sizeof(*new_jh));
2060         }
2061
2062         jbd_lock_bh_journal_head(bh);
2063         if (buffer_jbd(bh)) {
2064                 jh = bh2jh(bh);
2065         } else {
2066                 J_ASSERT_BH(bh,
2067                         (atomic_read(&bh->b_count) > 0) ||
2068                         (bh->b_page && bh->b_page->mapping));
2069
2070                 if (!new_jh) {
2071                         jbd_unlock_bh_journal_head(bh);
2072                         goto repeat;
2073                 }
2074
2075                 jh = new_jh;
2076                 new_jh = NULL;          /* We consumed it */
2077                 set_buffer_jbd(bh);
2078                 bh->b_private = jh;
2079                 jh->b_bh = bh;
2080                 get_bh(bh);
2081                 BUFFER_TRACE(bh, "added journal_head");
2082         }
2083         jh->b_jcount++;
2084         jbd_unlock_bh_journal_head(bh);
2085         if (new_jh)
2086                 journal_free_journal_head(new_jh);
2087         return bh->b_private;
2088 }
2089
2090 /*
2091  * Grab a ref against this buffer_head's journal_head.  If it ended up not
2092  * having a journal_head, return NULL
2093  */
2094 struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh)
2095 {
2096         struct journal_head *jh = NULL;
2097
2098         jbd_lock_bh_journal_head(bh);
2099         if (buffer_jbd(bh)) {
2100                 jh = bh2jh(bh);
2101                 jh->b_jcount++;
2102         }
2103         jbd_unlock_bh_journal_head(bh);
2104         return jh;
2105 }
2106
2107 static void __journal_remove_journal_head(struct buffer_head *bh)
2108 {
2109         struct journal_head *jh = bh2jh(bh);
2110
2111         J_ASSERT_JH(jh, jh->b_jcount >= 0);
2112
2113         get_bh(bh);
2114         if (jh->b_jcount == 0) {
2115                 if (jh->b_transaction == NULL &&
2116                                 jh->b_next_transaction == NULL &&
2117                                 jh->b_cp_transaction == NULL) {
2118                         J_ASSERT_JH(jh, jh->b_jlist == BJ_None);
2119                         J_ASSERT_BH(bh, buffer_jbd(bh));
2120                         J_ASSERT_BH(bh, jh2bh(jh) == bh);
2121                         BUFFER_TRACE(bh, "remove journal_head");
2122                         if (jh->b_frozen_data) {
2123                                 printk(KERN_WARNING "%s: freeing "
2124                                                 "b_frozen_data\n",
2125                                                 __func__);
2126                                 jbd2_free(jh->b_frozen_data, bh->b_size);
2127                         }
2128                         if (jh->b_committed_data) {
2129                                 printk(KERN_WARNING "%s: freeing "
2130                                                 "b_committed_data\n",
2131                                                 __func__);
2132                                 jbd2_free(jh->b_committed_data, bh->b_size);
2133                         }
2134                         bh->b_private = NULL;
2135                         jh->b_bh = NULL;        /* debug, really */
2136                         clear_buffer_jbd(bh);
2137                         __brelse(bh);
2138                         journal_free_journal_head(jh);
2139                 } else {
2140                         BUFFER_TRACE(bh, "journal_head was locked");
2141                 }
2142         }
2143 }
2144
2145 /*
2146  * jbd2_journal_remove_journal_head(): if the buffer isn't attached to a transaction
2147  * and has a zero b_jcount then remove and release its journal_head.   If we did
2148  * see that the buffer is not used by any transaction we also "logically"
2149  * decrement ->b_count.
2150  *
2151  * We in fact take an additional increment on ->b_count as a convenience,
2152  * because the caller usually wants to do additional things with the bh
2153  * after calling here.
2154  * The caller of jbd2_journal_remove_journal_head() *must* run __brelse(bh) at some
2155  * time.  Once the caller has run __brelse(), the buffer is eligible for
2156  * reaping by try_to_free_buffers().
2157  */
2158 void jbd2_journal_remove_journal_head(struct buffer_head *bh)
2159 {
2160         jbd_lock_bh_journal_head(bh);
2161         __journal_remove_journal_head(bh);
2162         jbd_unlock_bh_journal_head(bh);
2163 }
2164
2165 /*
2166  * Drop a reference on the passed journal_head.  If it fell to zero then try to
2167  * release the journal_head from the buffer_head.
2168  */
2169 void jbd2_journal_put_journal_head(struct journal_head *jh)
2170 {
2171         struct buffer_head *bh = jh2bh(jh);
2172
2173         jbd_lock_bh_journal_head(bh);
2174         J_ASSERT_JH(jh, jh->b_jcount > 0);
2175         --jh->b_jcount;
2176         if (!jh->b_jcount && !jh->b_transaction) {
2177                 __journal_remove_journal_head(bh);
2178                 __brelse(bh);
2179         }
2180         jbd_unlock_bh_journal_head(bh);
2181 }
2182
2183 /*
2184  * Initialize jbd inode head
2185  */
2186 void jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode)
2187 {
2188         jinode->i_transaction = NULL;
2189         jinode->i_next_transaction = NULL;
2190         jinode->i_vfs_inode = inode;
2191         jinode->i_flags = 0;
2192         INIT_LIST_HEAD(&jinode->i_list);
2193 }
2194
2195 /*
2196  * Function to be called before we start removing inode from memory (i.e.,
2197  * clear_inode() is a fine place to be called from). It removes inode from
2198  * transaction's lists.
2199  */
2200 void jbd2_journal_release_jbd_inode(journal_t *journal,
2201                                     struct jbd2_inode *jinode)
2202 {
2203         int writeout = 0;
2204
2205         if (!journal)
2206                 return;
2207 restart:
2208         spin_lock(&journal->j_list_lock);
2209         /* Is commit writing out inode - we have to wait */
2210         if (jinode->i_flags & JI_COMMIT_RUNNING) {
2211                 wait_queue_head_t *wq;
2212                 DEFINE_WAIT_BIT(wait, &jinode->i_flags, __JI_COMMIT_RUNNING);
2213                 wq = bit_waitqueue(&jinode->i_flags, __JI_COMMIT_RUNNING);
2214                 prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
2215                 spin_unlock(&journal->j_list_lock);
2216                 schedule();
2217                 finish_wait(wq, &wait.wait);
2218                 goto restart;
2219         }
2220
2221         /* Do we need to wait for data writeback? */
2222         if (journal->j_committing_transaction == jinode->i_transaction)
2223                 writeout = 1;
2224         if (jinode->i_transaction) {
2225                 list_del(&jinode->i_list);
2226                 jinode->i_transaction = NULL;
2227         }
2228         spin_unlock(&journal->j_list_lock);
2229 }
2230
2231 /*
2232  * debugfs tunables
2233  */
2234 #ifdef CONFIG_JBD2_DEBUG
2235 u8 jbd2_journal_enable_debug __read_mostly;
2236 EXPORT_SYMBOL(jbd2_journal_enable_debug);
2237
2238 #define JBD2_DEBUG_NAME "jbd2-debug"
2239
2240 static struct dentry *jbd2_debugfs_dir;
2241 static struct dentry *jbd2_debug;
2242
2243 static void __init jbd2_create_debugfs_entry(void)
2244 {
2245         jbd2_debugfs_dir = debugfs_create_dir("jbd2", NULL);
2246         if (jbd2_debugfs_dir)
2247                 jbd2_debug = debugfs_create_u8(JBD2_DEBUG_NAME, S_IRUGO,
2248                                                jbd2_debugfs_dir,
2249                                                &jbd2_journal_enable_debug);
2250 }
2251
2252 static void __exit jbd2_remove_debugfs_entry(void)
2253 {
2254         debugfs_remove(jbd2_debug);
2255         debugfs_remove(jbd2_debugfs_dir);
2256 }
2257
2258 #else
2259
2260 static void __init jbd2_create_debugfs_entry(void)
2261 {
2262 }
2263
2264 static void __exit jbd2_remove_debugfs_entry(void)
2265 {
2266 }
2267
2268 #endif
2269
2270 #ifdef CONFIG_PROC_FS
2271
2272 #define JBD2_STATS_PROC_NAME "fs/jbd2"
2273
2274 static void __init jbd2_create_jbd_stats_proc_entry(void)
2275 {
2276         proc_jbd2_stats = proc_mkdir(JBD2_STATS_PROC_NAME, NULL);
2277 }
2278
2279 static void __exit jbd2_remove_jbd_stats_proc_entry(void)
2280 {
2281         if (proc_jbd2_stats)
2282                 remove_proc_entry(JBD2_STATS_PROC_NAME, NULL);
2283 }
2284
2285 #else
2286
2287 #define jbd2_create_jbd_stats_proc_entry() do {} while (0)
2288 #define jbd2_remove_jbd_stats_proc_entry() do {} while (0)
2289
2290 #endif
2291
2292 struct kmem_cache *jbd2_handle_cache;
2293
2294 static int __init journal_init_handle_cache(void)
2295 {
2296         jbd2_handle_cache = kmem_cache_create("jbd2_journal_handle",
2297                                 sizeof(handle_t),
2298                                 0,              /* offset */
2299                                 SLAB_TEMPORARY, /* flags */
2300                                 NULL);          /* ctor */
2301         if (jbd2_handle_cache == NULL) {
2302                 printk(KERN_EMERG "JBD: failed to create handle cache\n");
2303                 return -ENOMEM;
2304         }
2305         return 0;
2306 }
2307
2308 static void jbd2_journal_destroy_handle_cache(void)
2309 {
2310         if (jbd2_handle_cache)
2311                 kmem_cache_destroy(jbd2_handle_cache);
2312 }
2313
2314 /*
2315  * Module startup and shutdown
2316  */
2317
2318 static int __init journal_init_caches(void)
2319 {
2320         int ret;
2321
2322         ret = jbd2_journal_init_revoke_caches();
2323         if (ret == 0)
2324                 ret = journal_init_jbd2_journal_head_cache();
2325         if (ret == 0)
2326                 ret = journal_init_handle_cache();
2327         return ret;
2328 }
2329
2330 static void jbd2_journal_destroy_caches(void)
2331 {
2332         jbd2_journal_destroy_revoke_caches();
2333         jbd2_journal_destroy_jbd2_journal_head_cache();
2334         jbd2_journal_destroy_handle_cache();
2335 }
2336
2337 static int __init journal_init(void)
2338 {
2339         int ret;
2340
2341         BUILD_BUG_ON(sizeof(struct journal_superblock_s) != 1024);
2342
2343         ret = journal_init_caches();
2344         if (ret == 0) {
2345                 jbd2_create_debugfs_entry();
2346                 jbd2_create_jbd_stats_proc_entry();
2347         } else {
2348                 jbd2_journal_destroy_caches();
2349         }
2350         return ret;
2351 }
2352
2353 static void __exit journal_exit(void)
2354 {
2355 #ifdef CONFIG_JBD2_DEBUG
2356         int n = atomic_read(&nr_journal_heads);
2357         if (n)
2358                 printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n);
2359 #endif
2360         jbd2_remove_debugfs_entry();
2361         jbd2_remove_jbd_stats_proc_entry();
2362         jbd2_journal_destroy_caches();
2363 }
2364
2365 MODULE_LICENSE("GPL");
2366 module_init(journal_init);
2367 module_exit(journal_exit);
2368