jbd: Move debug message into #ifdef area
[linux-3.10.git] / fs / jbd / recovery.c
1 /*
2  * linux/fs/jbd/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/jbd.h>
22 #include <linux/errno.h>
23 #endif
24
25 /*
26  * Maintain information about the progress of the recovery job, so that
27  * the different passes can carry information between them.
28  */
29 struct recovery_info
30 {
31         tid_t           start_transaction;
32         tid_t           end_transaction;
33
34         int             nr_replays;
35         int             nr_revokes;
36         int             nr_revoke_hits;
37 };
38
39 enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY};
40 static int do_one_pass(journal_t *journal,
41                                 struct recovery_info *info, enum passtype pass);
42 static int scan_revoke_records(journal_t *, struct buffer_head *,
43                                 tid_t, struct recovery_info *);
44
45 #ifdef __KERNEL__
46
47 /* Release readahead buffers after use */
48 static void journal_brelse_array(struct buffer_head *b[], int n)
49 {
50         while (--n >= 0)
51                 brelse (b[n]);
52 }
53
54
55 /*
56  * When reading from the journal, we are going through the block device
57  * layer directly and so there is no readahead being done for us.  We
58  * need to implement any readahead ourselves if we want it to happen at
59  * all.  Recovery is basically one long sequential read, so make sure we
60  * do the IO in reasonably large chunks.
61  *
62  * This is not so critical that we need to be enormously clever about
63  * the readahead size, though.  128K is a purely arbitrary, good-enough
64  * fixed value.
65  */
66
67 #define MAXBUF 8
68 static int do_readahead(journal_t *journal, unsigned int start)
69 {
70         int err;
71         unsigned int max, nbufs, next;
72         unsigned int blocknr;
73         struct buffer_head *bh;
74
75         struct buffer_head * bufs[MAXBUF];
76
77         /* Do up to 128K of readahead */
78         max = start + (128 * 1024 / journal->j_blocksize);
79         if (max > journal->j_maxlen)
80                 max = journal->j_maxlen;
81
82         /* Do the readahead itself.  We'll submit MAXBUF buffer_heads at
83          * a time to the block device IO layer. */
84
85         nbufs = 0;
86
87         for (next = start; next < max; next++) {
88                 err = journal_bmap(journal, next, &blocknr);
89
90                 if (err) {
91                         printk (KERN_ERR "JBD: bad block at offset %u\n",
92                                 next);
93                         goto failed;
94                 }
95
96                 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
97                 if (!bh) {
98                         err = -ENOMEM;
99                         goto failed;
100                 }
101
102                 if (!buffer_uptodate(bh) && !buffer_locked(bh)) {
103                         bufs[nbufs++] = bh;
104                         if (nbufs == MAXBUF) {
105                                 ll_rw_block(READ, nbufs, bufs);
106                                 journal_brelse_array(bufs, nbufs);
107                                 nbufs = 0;
108                         }
109                 } else
110                         brelse(bh);
111         }
112
113         if (nbufs)
114                 ll_rw_block(READ, nbufs, bufs);
115         err = 0;
116
117 failed:
118         if (nbufs)
119                 journal_brelse_array(bufs, nbufs);
120         return err;
121 }
122
123 #endif /* __KERNEL__ */
124
125
126 /*
127  * Read a block from the journal
128  */
129
130 static int jread(struct buffer_head **bhp, journal_t *journal,
131                  unsigned int offset)
132 {
133         int err;
134         unsigned int blocknr;
135         struct buffer_head *bh;
136
137         *bhp = NULL;
138
139         if (offset >= journal->j_maxlen) {
140                 printk(KERN_ERR "JBD: corrupted journal superblock\n");
141                 return -EIO;
142         }
143
144         err = journal_bmap(journal, offset, &blocknr);
145
146         if (err) {
147                 printk (KERN_ERR "JBD: bad block at offset %u\n",
148                         offset);
149                 return err;
150         }
151
152         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
153         if (!bh)
154                 return -ENOMEM;
155
156         if (!buffer_uptodate(bh)) {
157                 /* If this is a brand new buffer, start readahead.
158                    Otherwise, we assume we are already reading it.  */
159                 if (!buffer_req(bh))
160                         do_readahead(journal, offset);
161                 wait_on_buffer(bh);
162         }
163
164         if (!buffer_uptodate(bh)) {
165                 printk (KERN_ERR "JBD: Failed to read block at offset %u\n",
166                         offset);
167                 brelse(bh);
168                 return -EIO;
169         }
170
171         *bhp = bh;
172         return 0;
173 }
174
175
176 /*
177  * Count the number of in-use tags in a journal descriptor block.
178  */
179
180 static int count_tags(struct buffer_head *bh, int size)
181 {
182         char *                  tagp;
183         journal_block_tag_t *   tag;
184         int                     nr = 0;
185
186         tagp = &bh->b_data[sizeof(journal_header_t)];
187
188         while ((tagp - bh->b_data + sizeof(journal_block_tag_t)) <= size) {
189                 tag = (journal_block_tag_t *) tagp;
190
191                 nr++;
192                 tagp += sizeof(journal_block_tag_t);
193                 if (!(tag->t_flags & cpu_to_be32(JFS_FLAG_SAME_UUID)))
194                         tagp += 16;
195
196                 if (tag->t_flags & cpu_to_be32(JFS_FLAG_LAST_TAG))
197                         break;
198         }
199
200         return nr;
201 }
202
203
204 /* Make sure we wrap around the log correctly! */
205 #define wrap(journal, var)                                              \
206 do {                                                                    \
207         if (var >= (journal)->j_last)                                   \
208                 var -= ((journal)->j_last - (journal)->j_first);        \
209 } while (0)
210
211 /**
212  * journal_recover - recovers a on-disk journal
213  * @journal: the journal to recover
214  *
215  * The primary function for recovering the log contents when mounting a
216  * journaled device.
217  *
218  * Recovery is done in three passes.  In the first pass, we look for the
219  * end of the log.  In the second, we assemble the list of revoke
220  * blocks.  In the third and final pass, we replay any un-revoked blocks
221  * in the log.
222  */
223 int journal_recover(journal_t *journal)
224 {
225         int                     err, err2;
226         journal_superblock_t *  sb;
227
228         struct recovery_info    info;
229
230         memset(&info, 0, sizeof(info));
231         sb = journal->j_superblock;
232
233         /*
234          * The journal superblock's s_start field (the current log head)
235          * is always zero if, and only if, the journal was cleanly
236          * unmounted.
237          */
238
239         if (!sb->s_start) {
240                 jbd_debug(1, "No recovery required, last transaction %d\n",
241                           be32_to_cpu(sb->s_sequence));
242                 journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
243                 return 0;
244         }
245
246         err = do_one_pass(journal, &info, PASS_SCAN);
247         if (!err)
248                 err = do_one_pass(journal, &info, PASS_REVOKE);
249         if (!err)
250                 err = do_one_pass(journal, &info, PASS_REPLAY);
251
252         jbd_debug(1, "JBD: recovery, exit status %d, "
253                   "recovered transactions %u to %u\n",
254                   err, info.start_transaction, info.end_transaction);
255         jbd_debug(1, "JBD: Replayed %d and revoked %d/%d blocks\n",
256                   info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
257
258         /* Restart the log at the next transaction ID, thus invalidating
259          * any existing commit records in the log. */
260         journal->j_transaction_sequence = ++info.end_transaction;
261
262         journal_clear_revoke(journal);
263         err2 = sync_blockdev(journal->j_fs_dev);
264         if (!err)
265                 err = err2;
266
267         return err;
268 }
269
270 /**
271  * journal_skip_recovery - Start journal and wipe exiting records
272  * @journal: journal to startup
273  *
274  * Locate any valid recovery information from the journal and set up the
275  * journal structures in memory to ignore it (presumably because the
276  * caller has evidence that it is out of date).
277  * This function does'nt appear to be exorted..
278  *
279  * We perform one pass over the journal to allow us to tell the user how
280  * much recovery information is being erased, and to let us initialise
281  * the journal transaction sequence numbers to the next unused ID.
282  */
283 int journal_skip_recovery(journal_t *journal)
284 {
285         int                     err;
286         struct recovery_info    info;
287
288         memset (&info, 0, sizeof(info));
289
290         err = do_one_pass(journal, &info, PASS_SCAN);
291
292         if (err) {
293                 printk(KERN_ERR "JBD: error %d scanning journal\n", err);
294                 ++journal->j_transaction_sequence;
295         } else {
296 #ifdef CONFIG_JBD_DEBUG
297                 int dropped = info.end_transaction -
298                               be32_to_cpu(journal->j_superblock->s_sequence);
299                 jbd_debug(1,
300                           "JBD: ignoring %d transaction%s from the journal.\n",
301                           dropped, (dropped == 1) ? "" : "s");
302 #endif
303                 journal->j_transaction_sequence = ++info.end_transaction;
304         }
305
306         journal->j_tail = 0;
307         return err;
308 }
309
310 static int do_one_pass(journal_t *journal,
311                         struct recovery_info *info, enum passtype pass)
312 {
313         unsigned int            first_commit_ID, next_commit_ID;
314         unsigned int            next_log_block;
315         int                     err, success = 0;
316         journal_superblock_t *  sb;
317         journal_header_t *      tmp;
318         struct buffer_head *    bh;
319         unsigned int            sequence;
320         int                     blocktype;
321
322         /*
323          * First thing is to establish what we expect to find in the log
324          * (in terms of transaction IDs), and where (in terms of log
325          * block offsets): query the superblock.
326          */
327
328         sb = journal->j_superblock;
329         next_commit_ID = be32_to_cpu(sb->s_sequence);
330         next_log_block = be32_to_cpu(sb->s_start);
331
332         first_commit_ID = next_commit_ID;
333         if (pass == PASS_SCAN)
334                 info->start_transaction = first_commit_ID;
335
336         jbd_debug(1, "Starting recovery pass %d\n", pass);
337
338         /*
339          * Now we walk through the log, transaction by transaction,
340          * making sure that each transaction has a commit block in the
341          * expected place.  Each complete transaction gets replayed back
342          * into the main filesystem.
343          */
344
345         while (1) {
346                 int                     flags;
347                 char *                  tagp;
348                 journal_block_tag_t *   tag;
349                 struct buffer_head *    obh;
350                 struct buffer_head *    nbh;
351
352                 cond_resched();
353
354                 /* If we already know where to stop the log traversal,
355                  * check right now that we haven't gone past the end of
356                  * the log. */
357
358                 if (pass != PASS_SCAN)
359                         if (tid_geq(next_commit_ID, info->end_transaction))
360                                 break;
361
362                 jbd_debug(2, "Scanning for sequence ID %u at %u/%u\n",
363                           next_commit_ID, next_log_block, journal->j_last);
364
365                 /* Skip over each chunk of the transaction looking
366                  * either the next descriptor block or the final commit
367                  * record. */
368
369                 jbd_debug(3, "JBD: checking block %u\n", next_log_block);
370                 err = jread(&bh, journal, next_log_block);
371                 if (err)
372                         goto failed;
373
374                 next_log_block++;
375                 wrap(journal, next_log_block);
376
377                 /* What kind of buffer is it?
378                  *
379                  * If it is a descriptor block, check that it has the
380                  * expected sequence number.  Otherwise, we're all done
381                  * here. */
382
383                 tmp = (journal_header_t *)bh->b_data;
384
385                 if (tmp->h_magic != cpu_to_be32(JFS_MAGIC_NUMBER)) {
386                         brelse(bh);
387                         break;
388                 }
389
390                 blocktype = be32_to_cpu(tmp->h_blocktype);
391                 sequence = be32_to_cpu(tmp->h_sequence);
392                 jbd_debug(3, "Found magic %d, sequence %d\n",
393                           blocktype, sequence);
394
395                 if (sequence != next_commit_ID) {
396                         brelse(bh);
397                         break;
398                 }
399
400                 /* OK, we have a valid descriptor block which matches
401                  * all of the sequence number checks.  What are we going
402                  * to do with it?  That depends on the pass... */
403
404                 switch(blocktype) {
405                 case JFS_DESCRIPTOR_BLOCK:
406                         /* If it is a valid descriptor block, replay it
407                          * in pass REPLAY; otherwise, just skip over the
408                          * blocks it describes. */
409                         if (pass != PASS_REPLAY) {
410                                 next_log_block +=
411                                         count_tags(bh, journal->j_blocksize);
412                                 wrap(journal, next_log_block);
413                                 brelse(bh);
414                                 continue;
415                         }
416
417                         /* A descriptor block: we can now write all of
418                          * the data blocks.  Yay, useful work is finally
419                          * getting done here! */
420
421                         tagp = &bh->b_data[sizeof(journal_header_t)];
422                         while ((tagp - bh->b_data +sizeof(journal_block_tag_t))
423                                <= journal->j_blocksize) {
424                                 unsigned int io_block;
425
426                                 tag = (journal_block_tag_t *) tagp;
427                                 flags = be32_to_cpu(tag->t_flags);
428
429                                 io_block = next_log_block++;
430                                 wrap(journal, next_log_block);
431                                 err = jread(&obh, journal, io_block);
432                                 if (err) {
433                                         /* Recover what we can, but
434                                          * report failure at the end. */
435                                         success = err;
436                                         printk (KERN_ERR
437                                                 "JBD: IO error %d recovering "
438                                                 "block %u in log\n",
439                                                 err, io_block);
440                                 } else {
441                                         unsigned int blocknr;
442
443                                         J_ASSERT(obh != NULL);
444                                         blocknr = be32_to_cpu(tag->t_blocknr);
445
446                                         /* If the block has been
447                                          * revoked, then we're all done
448                                          * here. */
449                                         if (journal_test_revoke
450                                             (journal, blocknr,
451                                              next_commit_ID)) {
452                                                 brelse(obh);
453                                                 ++info->nr_revoke_hits;
454                                                 goto skip_write;
455                                         }
456
457                                         /* Find a buffer for the new
458                                          * data being restored */
459                                         nbh = __getblk(journal->j_fs_dev,
460                                                         blocknr,
461                                                         journal->j_blocksize);
462                                         if (nbh == NULL) {
463                                                 printk(KERN_ERR
464                                                        "JBD: Out of memory "
465                                                        "during recovery.\n");
466                                                 err = -ENOMEM;
467                                                 brelse(bh);
468                                                 brelse(obh);
469                                                 goto failed;
470                                         }
471
472                                         lock_buffer(nbh);
473                                         memcpy(nbh->b_data, obh->b_data,
474                                                         journal->j_blocksize);
475                                         if (flags & JFS_FLAG_ESCAPE) {
476                                                 *((__be32 *)nbh->b_data) =
477                                                 cpu_to_be32(JFS_MAGIC_NUMBER);
478                                         }
479
480                                         BUFFER_TRACE(nbh, "marking dirty");
481                                         set_buffer_uptodate(nbh);
482                                         mark_buffer_dirty(nbh);
483                                         BUFFER_TRACE(nbh, "marking uptodate");
484                                         ++info->nr_replays;
485                                         /* ll_rw_block(WRITE, 1, &nbh); */
486                                         unlock_buffer(nbh);
487                                         brelse(obh);
488                                         brelse(nbh);
489                                 }
490
491                         skip_write:
492                                 tagp += sizeof(journal_block_tag_t);
493                                 if (!(flags & JFS_FLAG_SAME_UUID))
494                                         tagp += 16;
495
496                                 if (flags & JFS_FLAG_LAST_TAG)
497                                         break;
498                         }
499
500                         brelse(bh);
501                         continue;
502
503                 case JFS_COMMIT_BLOCK:
504                         /* Found an expected commit block: not much to
505                          * do other than move on to the next sequence
506                          * number. */
507                         brelse(bh);
508                         next_commit_ID++;
509                         continue;
510
511                 case JFS_REVOKE_BLOCK:
512                         /* If we aren't in the REVOKE pass, then we can
513                          * just skip over this block. */
514                         if (pass != PASS_REVOKE) {
515                                 brelse(bh);
516                                 continue;
517                         }
518
519                         err = scan_revoke_records(journal, bh,
520                                                   next_commit_ID, info);
521                         brelse(bh);
522                         if (err)
523                                 goto failed;
524                         continue;
525
526                 default:
527                         jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
528                                   blocktype);
529                         brelse(bh);
530                         goto done;
531                 }
532         }
533
534  done:
535         /*
536          * We broke out of the log scan loop: either we came to the
537          * known end of the log or we found an unexpected block in the
538          * log.  If the latter happened, then we know that the "current"
539          * transaction marks the end of the valid log.
540          */
541
542         if (pass == PASS_SCAN)
543                 info->end_transaction = next_commit_ID;
544         else {
545                 /* It's really bad news if different passes end up at
546                  * different places (but possible due to IO errors). */
547                 if (info->end_transaction != next_commit_ID) {
548                         printk (KERN_ERR "JBD: recovery pass %d ended at "
549                                 "transaction %u, expected %u\n",
550                                 pass, next_commit_ID, info->end_transaction);
551                         if (!success)
552                                 success = -EIO;
553                 }
554         }
555
556         return success;
557
558  failed:
559         return err;
560 }
561
562
563 /* Scan a revoke record, marking all blocks mentioned as revoked. */
564
565 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
566                                tid_t sequence, struct recovery_info *info)
567 {
568         journal_revoke_header_t *header;
569         int offset, max;
570
571         header = (journal_revoke_header_t *) bh->b_data;
572         offset = sizeof(journal_revoke_header_t);
573         max = be32_to_cpu(header->r_count);
574
575         while (offset < max) {
576                 unsigned int blocknr;
577                 int err;
578
579                 blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
580                 offset += 4;
581                 err = journal_set_revoke(journal, blocknr, sequence);
582                 if (err)
583                         return err;
584                 ++info->nr_revokes;
585         }
586         return 0;
587 }