jbd2: delay discarding buffers in journal_unmap_buffer
[linux-2.6.git] / fs / jbd2 / recovery.c
1 /*
2  * linux/fs/jbd2/recovery.c
3  *
4  * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
5  *
6  * Copyright 1999-2000 Red Hat Software --- 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  * Journal recovery routines for the generic filesystem journaling code;
13  * part of the ext2fs journaling system.
14  */
15
16 #ifndef __KERNEL__
17 #include "jfs_user.h"
18 #else
19 #include <linux/time.h>
20 #include <linux/fs.h>
21 #include <linux/jbd2.h>
22 #include <linux/errno.h>
23 #include <linux/slab.h>
24 #include <linux/crc32.h>
25 #endif
26
27 /*
28  * Maintain information about the progress of the recovery job, so that
29  * the different passes can carry information between them.
30  */
31 struct recovery_info
32 {
33         tid_t           start_transaction;
34         tid_t           end_transaction;
35
36         int             nr_replays;
37         int             nr_revokes;
38         int             nr_revoke_hits;
39 };
40
41 enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY};
42 static int do_one_pass(journal_t *journal,
43                                 struct recovery_info *info, enum passtype pass);
44 static int scan_revoke_records(journal_t *, struct buffer_head *,
45                                 tid_t, struct recovery_info *);
46
47 #ifdef __KERNEL__
48
49 /* Release readahead buffers after use */
50 static void journal_brelse_array(struct buffer_head *b[], int n)
51 {
52         while (--n >= 0)
53                 brelse (b[n]);
54 }
55
56
57 /*
58  * When reading from the journal, we are going through the block device
59  * layer directly and so there is no readahead being done for us.  We
60  * need to implement any readahead ourselves if we want it to happen at
61  * all.  Recovery is basically one long sequential read, so make sure we
62  * do the IO in reasonably large chunks.
63  *
64  * This is not so critical that we need to be enormously clever about
65  * the readahead size, though.  128K is a purely arbitrary, good-enough
66  * fixed value.
67  */
68
69 #define MAXBUF 8
70 static int do_readahead(journal_t *journal, unsigned int start)
71 {
72         int err;
73         unsigned int max, nbufs, next;
74         unsigned long long blocknr;
75         struct buffer_head *bh;
76
77         struct buffer_head * bufs[MAXBUF];
78
79         /* Do up to 128K of readahead */
80         max = start + (128 * 1024 / journal->j_blocksize);
81         if (max > journal->j_maxlen)
82                 max = journal->j_maxlen;
83
84         /* Do the readahead itself.  We'll submit MAXBUF buffer_heads at
85          * a time to the block device IO layer. */
86
87         nbufs = 0;
88
89         for (next = start; next < max; next++) {
90                 err = jbd2_journal_bmap(journal, next, &blocknr);
91
92                 if (err) {
93                         printk (KERN_ERR "JBD: bad block at offset %u\n",
94                                 next);
95                         goto failed;
96                 }
97
98                 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
99                 if (!bh) {
100                         err = -ENOMEM;
101                         goto failed;
102                 }
103
104                 if (!buffer_uptodate(bh) && !buffer_locked(bh)) {
105                         bufs[nbufs++] = bh;
106                         if (nbufs == MAXBUF) {
107                                 ll_rw_block(READ, nbufs, bufs);
108                                 journal_brelse_array(bufs, nbufs);
109                                 nbufs = 0;
110                         }
111                 } else
112                         brelse(bh);
113         }
114
115         if (nbufs)
116                 ll_rw_block(READ, nbufs, bufs);
117         err = 0;
118
119 failed:
120         if (nbufs)
121                 journal_brelse_array(bufs, nbufs);
122         return err;
123 }
124
125 #endif /* __KERNEL__ */
126
127
128 /*
129  * Read a block from the journal
130  */
131
132 static int jread(struct buffer_head **bhp, journal_t *journal,
133                  unsigned int offset)
134 {
135         int err;
136         unsigned long long blocknr;
137         struct buffer_head *bh;
138
139         *bhp = NULL;
140
141         if (offset >= journal->j_maxlen) {
142                 printk(KERN_ERR "JBD: corrupted journal superblock\n");
143                 return -EIO;
144         }
145
146         err = jbd2_journal_bmap(journal, offset, &blocknr);
147
148         if (err) {
149                 printk (KERN_ERR "JBD: bad block at offset %u\n",
150                         offset);
151                 return err;
152         }
153
154         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
155         if (!bh)
156                 return -ENOMEM;
157
158         if (!buffer_uptodate(bh)) {
159                 /* If this is a brand new buffer, start readahead.
160                    Otherwise, we assume we are already reading it.  */
161                 if (!buffer_req(bh))
162                         do_readahead(journal, offset);
163                 wait_on_buffer(bh);
164         }
165
166         if (!buffer_uptodate(bh)) {
167                 printk (KERN_ERR "JBD: Failed to read block at offset %u\n",
168                         offset);
169                 brelse(bh);
170                 return -EIO;
171         }
172
173         *bhp = bh;
174         return 0;
175 }
176
177
178 /*
179  * Count the number of in-use tags in a journal descriptor block.
180  */
181
182 static int count_tags(journal_t *journal, struct buffer_head *bh)
183 {
184         char *                  tagp;
185         journal_block_tag_t *   tag;
186         int                     nr = 0, size = journal->j_blocksize;
187         int                     tag_bytes = journal_tag_bytes(journal);
188
189         tagp = &bh->b_data[sizeof(journal_header_t)];
190
191         while ((tagp - bh->b_data + tag_bytes) <= size) {
192                 tag = (journal_block_tag_t *) tagp;
193
194                 nr++;
195                 tagp += tag_bytes;
196                 if (!(tag->t_flags & cpu_to_be32(JBD2_FLAG_SAME_UUID)))
197                         tagp += 16;
198
199                 if (tag->t_flags & cpu_to_be32(JBD2_FLAG_LAST_TAG))
200                         break;
201         }
202
203         return nr;
204 }
205
206
207 /* Make sure we wrap around the log correctly! */
208 #define wrap(journal, var)                                              \
209 do {                                                                    \
210         if (var >= (journal)->j_last)                                   \
211                 var -= ((journal)->j_last - (journal)->j_first);        \
212 } while (0)
213
214 /**
215  * jbd2_journal_recover - recovers a on-disk journal
216  * @journal: the journal to recover
217  *
218  * The primary function for recovering the log contents when mounting a
219  * journaled device.
220  *
221  * Recovery is done in three passes.  In the first pass, we look for the
222  * end of the log.  In the second, we assemble the list of revoke
223  * blocks.  In the third and final pass, we replay any un-revoked blocks
224  * in the log.
225  */
226 int jbd2_journal_recover(journal_t *journal)
227 {
228         int                     err, err2;
229         journal_superblock_t *  sb;
230
231         struct recovery_info    info;
232
233         memset(&info, 0, sizeof(info));
234         sb = journal->j_superblock;
235
236         /*
237          * The journal superblock's s_start field (the current log head)
238          * is always zero if, and only if, the journal was cleanly
239          * unmounted.
240          */
241
242         if (!sb->s_start) {
243                 jbd_debug(1, "No recovery required, last transaction %d\n",
244                           be32_to_cpu(sb->s_sequence));
245                 journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
246                 return 0;
247         }
248
249         err = do_one_pass(journal, &info, PASS_SCAN);
250         if (!err)
251                 err = do_one_pass(journal, &info, PASS_REVOKE);
252         if (!err)
253                 err = do_one_pass(journal, &info, PASS_REPLAY);
254
255         jbd_debug(1, "JBD: recovery, exit status %d, "
256                   "recovered transactions %u to %u\n",
257                   err, info.start_transaction, info.end_transaction);
258         jbd_debug(1, "JBD: Replayed %d and revoked %d/%d blocks\n",
259                   info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
260
261         /* Restart the log at the next transaction ID, thus invalidating
262          * any existing commit records in the log. */
263         journal->j_transaction_sequence = ++info.end_transaction;
264
265         jbd2_journal_clear_revoke(journal);
266         err2 = sync_blockdev(journal->j_fs_dev);
267         if (!err)
268                 err = err2;
269
270         return err;
271 }
272
273 /**
274  * jbd2_journal_skip_recovery - Start journal and wipe exiting records
275  * @journal: journal to startup
276  *
277  * Locate any valid recovery information from the journal and set up the
278  * journal structures in memory to ignore it (presumably because the
279  * caller has evidence that it is out of date).
280  * This function does'nt appear to be exorted..
281  *
282  * We perform one pass over the journal to allow us to tell the user how
283  * much recovery information is being erased, and to let us initialise
284  * the journal transaction sequence numbers to the next unused ID.
285  */
286 int jbd2_journal_skip_recovery(journal_t *journal)
287 {
288         int                     err;
289         journal_superblock_t *  sb;
290
291         struct recovery_info    info;
292
293         memset (&info, 0, sizeof(info));
294         sb = journal->j_superblock;
295
296         err = do_one_pass(journal, &info, PASS_SCAN);
297
298         if (err) {
299                 printk(KERN_ERR "JBD: error %d scanning journal\n", err);
300                 ++journal->j_transaction_sequence;
301         } else {
302 #ifdef CONFIG_JBD2_DEBUG
303                 int dropped = info.end_transaction - be32_to_cpu(sb->s_sequence);
304 #endif
305                 jbd_debug(1,
306                           "JBD: ignoring %d transaction%s from the journal.\n",
307                           dropped, (dropped == 1) ? "" : "s");
308                 journal->j_transaction_sequence = ++info.end_transaction;
309         }
310
311         journal->j_tail = 0;
312         return err;
313 }
314
315 static inline unsigned long long read_tag_block(int tag_bytes, journal_block_tag_t *tag)
316 {
317         unsigned long long block = be32_to_cpu(tag->t_blocknr);
318         if (tag_bytes > JBD2_TAG_SIZE32)
319                 block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
320         return block;
321 }
322
323 /*
324  * calc_chksums calculates the checksums for the blocks described in the
325  * descriptor block.
326  */
327 static int calc_chksums(journal_t *journal, struct buffer_head *bh,
328                         unsigned long *next_log_block, __u32 *crc32_sum)
329 {
330         int i, num_blks, err;
331         unsigned long io_block;
332         struct buffer_head *obh;
333
334         num_blks = count_tags(journal, bh);
335         /* Calculate checksum of the descriptor block. */
336         *crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
337
338         for (i = 0; i < num_blks; i++) {
339                 io_block = (*next_log_block)++;
340                 wrap(journal, *next_log_block);
341                 err = jread(&obh, journal, io_block);
342                 if (err) {
343                         printk(KERN_ERR "JBD: IO error %d recovering block "
344                                 "%lu in log\n", err, io_block);
345                         return 1;
346                 } else {
347                         *crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
348                                      obh->b_size);
349                 }
350                 put_bh(obh);
351         }
352         return 0;
353 }
354
355 static int do_one_pass(journal_t *journal,
356                         struct recovery_info *info, enum passtype pass)
357 {
358         unsigned int            first_commit_ID, next_commit_ID;
359         unsigned long           next_log_block;
360         int                     err, success = 0;
361         journal_superblock_t *  sb;
362         journal_header_t *      tmp;
363         struct buffer_head *    bh;
364         unsigned int            sequence;
365         int                     blocktype;
366         int                     tag_bytes = journal_tag_bytes(journal);
367         __u32                   crc32_sum = ~0; /* Transactional Checksums */
368
369         /* Precompute the maximum metadata descriptors in a descriptor block */
370         int                     MAX_BLOCKS_PER_DESC;
371         MAX_BLOCKS_PER_DESC = ((journal->j_blocksize-sizeof(journal_header_t))
372                                / tag_bytes);
373
374         /*
375          * First thing is to establish what we expect to find in the log
376          * (in terms of transaction IDs), and where (in terms of log
377          * block offsets): query the superblock.
378          */
379
380         sb = journal->j_superblock;
381         next_commit_ID = be32_to_cpu(sb->s_sequence);
382         next_log_block = be32_to_cpu(sb->s_start);
383
384         first_commit_ID = next_commit_ID;
385         if (pass == PASS_SCAN)
386                 info->start_transaction = first_commit_ID;
387
388         jbd_debug(1, "Starting recovery pass %d\n", pass);
389
390         /*
391          * Now we walk through the log, transaction by transaction,
392          * making sure that each transaction has a commit block in the
393          * expected place.  Each complete transaction gets replayed back
394          * into the main filesystem.
395          */
396
397         while (1) {
398                 int                     flags;
399                 char *                  tagp;
400                 journal_block_tag_t *   tag;
401                 struct buffer_head *    obh;
402                 struct buffer_head *    nbh;
403
404                 cond_resched();
405
406                 /* If we already know where to stop the log traversal,
407                  * check right now that we haven't gone past the end of
408                  * the log. */
409
410                 if (pass != PASS_SCAN)
411                         if (tid_geq(next_commit_ID, info->end_transaction))
412                                 break;
413
414                 jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
415                           next_commit_ID, next_log_block, journal->j_last);
416
417                 /* Skip over each chunk of the transaction looking
418                  * either the next descriptor block or the final commit
419                  * record. */
420
421                 jbd_debug(3, "JBD: checking block %ld\n", next_log_block);
422                 err = jread(&bh, journal, next_log_block);
423                 if (err)
424                         goto failed;
425
426                 next_log_block++;
427                 wrap(journal, next_log_block);
428
429                 /* What kind of buffer is it?
430                  *
431                  * If it is a descriptor block, check that it has the
432                  * expected sequence number.  Otherwise, we're all done
433                  * here. */
434
435                 tmp = (journal_header_t *)bh->b_data;
436
437                 if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
438                         brelse(bh);
439                         break;
440                 }
441
442                 blocktype = be32_to_cpu(tmp->h_blocktype);
443                 sequence = be32_to_cpu(tmp->h_sequence);
444                 jbd_debug(3, "Found magic %d, sequence %d\n",
445                           blocktype, sequence);
446
447                 if (sequence != next_commit_ID) {
448                         brelse(bh);
449                         break;
450                 }
451
452                 /* OK, we have a valid descriptor block which matches
453                  * all of the sequence number checks.  What are we going
454                  * to do with it?  That depends on the pass... */
455
456                 switch(blocktype) {
457                 case JBD2_DESCRIPTOR_BLOCK:
458                         /* If it is a valid descriptor block, replay it
459                          * in pass REPLAY; if journal_checksums enabled, then
460                          * calculate checksums in PASS_SCAN, otherwise,
461                          * just skip over the blocks it describes. */
462                         if (pass != PASS_REPLAY) {
463                                 if (pass == PASS_SCAN &&
464                                     JBD2_HAS_COMPAT_FEATURE(journal,
465                                             JBD2_FEATURE_COMPAT_CHECKSUM) &&
466                                     !info->end_transaction) {
467                                         if (calc_chksums(journal, bh,
468                                                         &next_log_block,
469                                                         &crc32_sum)) {
470                                                 put_bh(bh);
471                                                 break;
472                                         }
473                                         put_bh(bh);
474                                         continue;
475                                 }
476                                 next_log_block += count_tags(journal, bh);
477                                 wrap(journal, next_log_block);
478                                 put_bh(bh);
479                                 continue;
480                         }
481
482                         /* A descriptor block: we can now write all of
483                          * the data blocks.  Yay, useful work is finally
484                          * getting done here! */
485
486                         tagp = &bh->b_data[sizeof(journal_header_t)];
487                         while ((tagp - bh->b_data + tag_bytes)
488                                <= journal->j_blocksize) {
489                                 unsigned long io_block;
490
491                                 tag = (journal_block_tag_t *) tagp;
492                                 flags = be32_to_cpu(tag->t_flags);
493
494                                 io_block = next_log_block++;
495                                 wrap(journal, next_log_block);
496                                 err = jread(&obh, journal, io_block);
497                                 if (err) {
498                                         /* Recover what we can, but
499                                          * report failure at the end. */
500                                         success = err;
501                                         printk (KERN_ERR
502                                                 "JBD: IO error %d recovering "
503                                                 "block %ld in log\n",
504                                                 err, io_block);
505                                 } else {
506                                         unsigned long long blocknr;
507
508                                         J_ASSERT(obh != NULL);
509                                         blocknr = read_tag_block(tag_bytes,
510                                                                  tag);
511
512                                         /* If the block has been
513                                          * revoked, then we're all done
514                                          * here. */
515                                         if (jbd2_journal_test_revoke
516                                             (journal, blocknr,
517                                              next_commit_ID)) {
518                                                 brelse(obh);
519                                                 ++info->nr_revoke_hits;
520                                                 goto skip_write;
521                                         }
522
523                                         /* Find a buffer for the new
524                                          * data being restored */
525                                         nbh = __getblk(journal->j_fs_dev,
526                                                         blocknr,
527                                                         journal->j_blocksize);
528                                         if (nbh == NULL) {
529                                                 printk(KERN_ERR
530                                                        "JBD: Out of memory "
531                                                        "during recovery.\n");
532                                                 err = -ENOMEM;
533                                                 brelse(bh);
534                                                 brelse(obh);
535                                                 goto failed;
536                                         }
537
538                                         lock_buffer(nbh);
539                                         memcpy(nbh->b_data, obh->b_data,
540                                                         journal->j_blocksize);
541                                         if (flags & JBD2_FLAG_ESCAPE) {
542                                                 *((__be32 *)nbh->b_data) =
543                                                 cpu_to_be32(JBD2_MAGIC_NUMBER);
544                                         }
545
546                                         BUFFER_TRACE(nbh, "marking dirty");
547                                         set_buffer_uptodate(nbh);
548                                         mark_buffer_dirty(nbh);
549                                         BUFFER_TRACE(nbh, "marking uptodate");
550                                         ++info->nr_replays;
551                                         /* ll_rw_block(WRITE, 1, &nbh); */
552                                         unlock_buffer(nbh);
553                                         brelse(obh);
554                                         brelse(nbh);
555                                 }
556
557                         skip_write:
558                                 tagp += tag_bytes;
559                                 if (!(flags & JBD2_FLAG_SAME_UUID))
560                                         tagp += 16;
561
562                                 if (flags & JBD2_FLAG_LAST_TAG)
563                                         break;
564                         }
565
566                         brelse(bh);
567                         continue;
568
569                 case JBD2_COMMIT_BLOCK:
570                         /*     How to differentiate between interrupted commit
571                          *               and journal corruption ?
572                          *
573                          * {nth transaction}
574                          *        Checksum Verification Failed
575                          *                       |
576                          *               ____________________
577                          *              |                    |
578                          *      async_commit             sync_commit
579                          *              |                    |
580                          *              | GO TO NEXT    "Journal Corruption"
581                          *              | TRANSACTION
582                          *              |
583                          * {(n+1)th transanction}
584                          *              |
585                          *       _______|______________
586                          *      |                     |
587                          * Commit block found   Commit block not found
588                          *      |                     |
589                          * "Journal Corruption"       |
590                          *               _____________|_________
591                          *              |                       |
592                          *      nth trans corrupt       OR   nth trans
593                          *      and (n+1)th interrupted     interrupted
594                          *      before commit block
595                          *      could reach the disk.
596                          *      (Cannot find the difference in above
597                          *       mentioned conditions. Hence assume
598                          *       "Interrupted Commit".)
599                          */
600
601                         /* Found an expected commit block: if checksums
602                          * are present verify them in PASS_SCAN; else not
603                          * much to do other than move on to the next sequence
604                          * number. */
605                         if (pass == PASS_SCAN &&
606                             JBD2_HAS_COMPAT_FEATURE(journal,
607                                     JBD2_FEATURE_COMPAT_CHECKSUM)) {
608                                 int chksum_err, chksum_seen;
609                                 struct commit_header *cbh =
610                                         (struct commit_header *)bh->b_data;
611                                 unsigned found_chksum =
612                                         be32_to_cpu(cbh->h_chksum[0]);
613
614                                 chksum_err = chksum_seen = 0;
615
616                                 if (info->end_transaction) {
617                                         journal->j_failed_commit =
618                                                 info->end_transaction;
619                                         brelse(bh);
620                                         break;
621                                 }
622
623                                 if (crc32_sum == found_chksum &&
624                                     cbh->h_chksum_type == JBD2_CRC32_CHKSUM &&
625                                     cbh->h_chksum_size ==
626                                                 JBD2_CRC32_CHKSUM_SIZE)
627                                        chksum_seen = 1;
628                                 else if (!(cbh->h_chksum_type == 0 &&
629                                              cbh->h_chksum_size == 0 &&
630                                              found_chksum == 0 &&
631                                              !chksum_seen))
632                                 /*
633                                  * If fs is mounted using an old kernel and then
634                                  * kernel with journal_chksum is used then we
635                                  * get a situation where the journal flag has
636                                  * checksum flag set but checksums are not
637                                  * present i.e chksum = 0, in the individual
638                                  * commit blocks.
639                                  * Hence to avoid checksum failures, in this
640                                  * situation, this extra check is added.
641                                  */
642                                                 chksum_err = 1;
643
644                                 if (chksum_err) {
645                                         info->end_transaction = next_commit_ID;
646
647                                         if (!JBD2_HAS_INCOMPAT_FEATURE(journal,
648                                            JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)){
649                                                 journal->j_failed_commit =
650                                                         next_commit_ID;
651                                                 brelse(bh);
652                                                 break;
653                                         }
654                                 }
655                                 crc32_sum = ~0;
656                         }
657                         brelse(bh);
658                         next_commit_ID++;
659                         continue;
660
661                 case JBD2_REVOKE_BLOCK:
662                         /* If we aren't in the REVOKE pass, then we can
663                          * just skip over this block. */
664                         if (pass != PASS_REVOKE) {
665                                 brelse(bh);
666                                 continue;
667                         }
668
669                         err = scan_revoke_records(journal, bh,
670                                                   next_commit_ID, info);
671                         brelse(bh);
672                         if (err)
673                                 goto failed;
674                         continue;
675
676                 default:
677                         jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
678                                   blocktype);
679                         brelse(bh);
680                         goto done;
681                 }
682         }
683
684  done:
685         /*
686          * We broke out of the log scan loop: either we came to the
687          * known end of the log or we found an unexpected block in the
688          * log.  If the latter happened, then we know that the "current"
689          * transaction marks the end of the valid log.
690          */
691
692         if (pass == PASS_SCAN) {
693                 if (!info->end_transaction)
694                         info->end_transaction = next_commit_ID;
695         } else {
696                 /* It's really bad news if different passes end up at
697                  * different places (but possible due to IO errors). */
698                 if (info->end_transaction != next_commit_ID) {
699                         printk (KERN_ERR "JBD: recovery pass %d ended at "
700                                 "transaction %u, expected %u\n",
701                                 pass, next_commit_ID, info->end_transaction);
702                         if (!success)
703                                 success = -EIO;
704                 }
705         }
706
707         return success;
708
709  failed:
710         return err;
711 }
712
713
714 /* Scan a revoke record, marking all blocks mentioned as revoked. */
715
716 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
717                                tid_t sequence, struct recovery_info *info)
718 {
719         jbd2_journal_revoke_header_t *header;
720         int offset, max;
721         int record_len = 4;
722
723         header = (jbd2_journal_revoke_header_t *) bh->b_data;
724         offset = sizeof(jbd2_journal_revoke_header_t);
725         max = be32_to_cpu(header->r_count);
726
727         if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
728                 record_len = 8;
729
730         while (offset + record_len <= max) {
731                 unsigned long long blocknr;
732                 int err;
733
734                 if (record_len == 4)
735                         blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
736                 else
737                         blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
738                 offset += record_len;
739                 err = jbd2_journal_set_revoke(journal, blocknr, sequence);
740                 if (err)
741                         return err;
742                 ++info->nr_revokes;
743         }
744         return 0;
745 }