USB: r8a66597-hcd: fix NULL access
[linux-2.6] / 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 #endif
25
26 /*
27  * Maintain information about the progress of the recovery job, so that
28  * the different passes can carry information between them.
29  */
30 struct recovery_info
31 {
32         tid_t           start_transaction;
33         tid_t           end_transaction;
34
35         int             nr_replays;
36         int             nr_revokes;
37         int             nr_revoke_hits;
38 };
39
40 enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY};
41 static int do_one_pass(journal_t *journal,
42                                 struct recovery_info *info, enum passtype pass);
43 static int scan_revoke_records(journal_t *, struct buffer_head *,
44                                 tid_t, struct recovery_info *);
45
46 #ifdef __KERNEL__
47
48 /* Release readahead buffers after use */
49 static void journal_brelse_array(struct buffer_head *b[], int n)
50 {
51         while (--n >= 0)
52                 brelse (b[n]);
53 }
54
55
56 /*
57  * When reading from the journal, we are going through the block device
58  * layer directly and so there is no readahead being done for us.  We
59  * need to implement any readahead ourselves if we want it to happen at
60  * all.  Recovery is basically one long sequential read, so make sure we
61  * do the IO in reasonably large chunks.
62  *
63  * This is not so critical that we need to be enormously clever about
64  * the readahead size, though.  128K is a purely arbitrary, good-enough
65  * fixed value.
66  */
67
68 #define MAXBUF 8
69 static int do_readahead(journal_t *journal, unsigned int start)
70 {
71         int err;
72         unsigned int max, nbufs, next;
73         unsigned long long blocknr;
74         struct buffer_head *bh;
75
76         struct buffer_head * bufs[MAXBUF];
77
78         /* Do up to 128K of readahead */
79         max = start + (128 * 1024 / journal->j_blocksize);
80         if (max > journal->j_maxlen)
81                 max = journal->j_maxlen;
82
83         /* Do the readahead itself.  We'll submit MAXBUF buffer_heads at
84          * a time to the block device IO layer. */
85
86         nbufs = 0;
87
88         for (next = start; next < max; next++) {
89                 err = jbd2_journal_bmap(journal, next, &blocknr);
90
91                 if (err) {
92                         printk (KERN_ERR "JBD: bad block at offset %u\n",
93                                 next);
94                         goto failed;
95                 }
96
97                 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
98                 if (!bh) {
99                         err = -ENOMEM;
100                         goto failed;
101                 }
102
103                 if (!buffer_uptodate(bh) && !buffer_locked(bh)) {
104                         bufs[nbufs++] = bh;
105                         if (nbufs == MAXBUF) {
106                                 ll_rw_block(READ, nbufs, bufs);
107                                 journal_brelse_array(bufs, nbufs);
108                                 nbufs = 0;
109                         }
110                 } else
111                         brelse(bh);
112         }
113
114         if (nbufs)
115                 ll_rw_block(READ, nbufs, bufs);
116         err = 0;
117
118 failed:
119         if (nbufs)
120                 journal_brelse_array(bufs, nbufs);
121         return err;
122 }
123
124 #endif /* __KERNEL__ */
125
126
127 /*
128  * Read a block from the journal
129  */
130
131 static int jread(struct buffer_head **bhp, journal_t *journal,
132                  unsigned int offset)
133 {
134         int err;
135         unsigned long long blocknr;
136         struct buffer_head *bh;
137
138         *bhp = NULL;
139
140         if (offset >= journal->j_maxlen) {
141                 printk(KERN_ERR "JBD: corrupted journal superblock\n");
142                 return -EIO;
143         }
144
145         err = jbd2_journal_bmap(journal, offset, &blocknr);
146
147         if (err) {
148                 printk (KERN_ERR "JBD: bad block at offset %u\n",
149                         offset);
150                 return err;
151         }
152
153         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
154         if (!bh)
155                 return -ENOMEM;
156
157         if (!buffer_uptodate(bh)) {
158                 /* If this is a brand new buffer, start readahead.
159                    Otherwise, we assume we are already reading it.  */
160                 if (!buffer_req(bh))
161                         do_readahead(journal, offset);
162                 wait_on_buffer(bh);
163         }
164
165         if (!buffer_uptodate(bh)) {
166                 printk (KERN_ERR "JBD: Failed to read block at offset %u\n",
167                         offset);
168                 brelse(bh);
169                 return -EIO;
170         }
171
172         *bhp = bh;
173         return 0;
174 }
175
176
177 /*
178  * Count the number of in-use tags in a journal descriptor block.
179  */
180
181 static int count_tags(journal_t *journal, struct buffer_head *bh)
182 {
183         char *                  tagp;
184         journal_block_tag_t *   tag;
185         int                     nr = 0, size = journal->j_blocksize;
186         int                     tag_bytes = journal_tag_bytes(journal);
187
188         tagp = &bh->b_data[sizeof(journal_header_t)];
189
190         while ((tagp - bh->b_data + tag_bytes) <= size) {
191                 tag = (journal_block_tag_t *) tagp;
192
193                 nr++;
194                 tagp += tag_bytes;
195                 if (!(tag->t_flags & cpu_to_be32(JBD2_FLAG_SAME_UUID)))
196                         tagp += 16;
197
198                 if (tag->t_flags & cpu_to_be32(JBD2_FLAG_LAST_TAG))
199                         break;
200         }
201
202         return nr;
203 }
204
205
206 /* Make sure we wrap around the log correctly! */
207 #define wrap(journal, var)                                              \
208 do {                                                                    \
209         if (var >= (journal)->j_last)                                   \
210                 var -= ((journal)->j_last - (journal)->j_first);        \
211 } while (0)
212
213 /**
214  * jbd2_journal_recover - recovers a on-disk journal
215  * @journal: the journal to recover
216  *
217  * The primary function for recovering the log contents when mounting a
218  * journaled device.
219  *
220  * Recovery is done in three passes.  In the first pass, we look for the
221  * end of the log.  In the second, we assemble the list of revoke
222  * blocks.  In the third and final pass, we replay any un-revoked blocks
223  * in the log.
224  */
225 int jbd2_journal_recover(journal_t *journal)
226 {
227         int                     err;
228         journal_superblock_t *  sb;
229
230         struct recovery_info    info;
231
232         memset(&info, 0, sizeof(info));
233         sb = journal->j_superblock;
234
235         /*
236          * The journal superblock's s_start field (the current log head)
237          * is always zero if, and only if, the journal was cleanly
238          * unmounted.
239          */
240
241         if (!sb->s_start) {
242                 jbd_debug(1, "No recovery required, last transaction %d\n",
243                           be32_to_cpu(sb->s_sequence));
244                 journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
245                 return 0;
246         }
247
248         err = do_one_pass(journal, &info, PASS_SCAN);
249         if (!err)
250                 err = do_one_pass(journal, &info, PASS_REVOKE);
251         if (!err)
252                 err = do_one_pass(journal, &info, PASS_REPLAY);
253
254         jbd_debug(0, "JBD: recovery, exit status %d, "
255                   "recovered transactions %u to %u\n",
256                   err, info.start_transaction, info.end_transaction);
257         jbd_debug(0, "JBD: Replayed %d and revoked %d/%d blocks\n",
258                   info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
259
260         /* Restart the log at the next transaction ID, thus invalidating
261          * any existing commit records in the log. */
262         journal->j_transaction_sequence = ++info.end_transaction;
263
264         jbd2_journal_clear_revoke(journal);
265         sync_blockdev(journal->j_fs_dev);
266         return err;
267 }
268
269 /**
270  * jbd2_journal_skip_recovery - Start journal and wipe exiting records
271  * @journal: journal to startup
272  *
273  * Locate any valid recovery information from the journal and set up the
274  * journal structures in memory to ignore it (presumably because the
275  * caller has evidence that it is out of date).
276  * This function does'nt appear to be exorted..
277  *
278  * We perform one pass over the journal to allow us to tell the user how
279  * much recovery information is being erased, and to let us initialise
280  * the journal transaction sequence numbers to the next unused ID.
281  */
282 int jbd2_journal_skip_recovery(journal_t *journal)
283 {
284         int                     err;
285         journal_superblock_t *  sb;
286
287         struct recovery_info    info;
288
289         memset (&info, 0, sizeof(info));
290         sb = journal->j_superblock;
291
292         err = do_one_pass(journal, &info, PASS_SCAN);
293
294         if (err) {
295                 printk(KERN_ERR "JBD: error %d scanning journal\n", err);
296                 ++journal->j_transaction_sequence;
297         } else {
298 #ifdef CONFIG_JBD_DEBUG
299                 int dropped = info.end_transaction - be32_to_cpu(sb->s_sequence);
300 #endif
301                 jbd_debug(0,
302                           "JBD: ignoring %d transaction%s from the journal.\n",
303                           dropped, (dropped == 1) ? "" : "s");
304                 journal->j_transaction_sequence = ++info.end_transaction;
305         }
306
307         journal->j_tail = 0;
308         return err;
309 }
310
311 static inline unsigned long long read_tag_block(int tag_bytes, journal_block_tag_t *tag)
312 {
313         unsigned long long block = be32_to_cpu(tag->t_blocknr);
314         if (tag_bytes > JBD_TAG_SIZE32)
315                 block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
316         return block;
317 }
318
319 static int do_one_pass(journal_t *journal,
320                         struct recovery_info *info, enum passtype pass)
321 {
322         unsigned int            first_commit_ID, next_commit_ID;
323         unsigned long           next_log_block;
324         int                     err, success = 0;
325         journal_superblock_t *  sb;
326         journal_header_t *      tmp;
327         struct buffer_head *    bh;
328         unsigned int            sequence;
329         int                     blocktype;
330         int                     tag_bytes = journal_tag_bytes(journal);
331
332         /* Precompute the maximum metadata descriptors in a descriptor block */
333         int                     MAX_BLOCKS_PER_DESC;
334         MAX_BLOCKS_PER_DESC = ((journal->j_blocksize-sizeof(journal_header_t))
335                                / tag_bytes);
336
337         /*
338          * First thing is to establish what we expect to find in the log
339          * (in terms of transaction IDs), and where (in terms of log
340          * block offsets): query the superblock.
341          */
342
343         sb = journal->j_superblock;
344         next_commit_ID = be32_to_cpu(sb->s_sequence);
345         next_log_block = be32_to_cpu(sb->s_start);
346
347         first_commit_ID = next_commit_ID;
348         if (pass == PASS_SCAN)
349                 info->start_transaction = first_commit_ID;
350
351         jbd_debug(1, "Starting recovery pass %d\n", pass);
352
353         /*
354          * Now we walk through the log, transaction by transaction,
355          * making sure that each transaction has a commit block in the
356          * expected place.  Each complete transaction gets replayed back
357          * into the main filesystem.
358          */
359
360         while (1) {
361                 int                     flags;
362                 char *                  tagp;
363                 journal_block_tag_t *   tag;
364                 struct buffer_head *    obh;
365                 struct buffer_head *    nbh;
366
367                 cond_resched();         /* We're under lock_kernel() */
368
369                 /* If we already know where to stop the log traversal,
370                  * check right now that we haven't gone past the end of
371                  * the log. */
372
373                 if (pass != PASS_SCAN)
374                         if (tid_geq(next_commit_ID, info->end_transaction))
375                                 break;
376
377                 jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
378                           next_commit_ID, next_log_block, journal->j_last);
379
380                 /* Skip over each chunk of the transaction looking
381                  * either the next descriptor block or the final commit
382                  * record. */
383
384                 jbd_debug(3, "JBD: checking block %ld\n", next_log_block);
385                 err = jread(&bh, journal, next_log_block);
386                 if (err)
387                         goto failed;
388
389                 next_log_block++;
390                 wrap(journal, next_log_block);
391
392                 /* What kind of buffer is it?
393                  *
394                  * If it is a descriptor block, check that it has the
395                  * expected sequence number.  Otherwise, we're all done
396                  * here. */
397
398                 tmp = (journal_header_t *)bh->b_data;
399
400                 if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
401                         brelse(bh);
402                         break;
403                 }
404
405                 blocktype = be32_to_cpu(tmp->h_blocktype);
406                 sequence = be32_to_cpu(tmp->h_sequence);
407                 jbd_debug(3, "Found magic %d, sequence %d\n",
408                           blocktype, sequence);
409
410                 if (sequence != next_commit_ID) {
411                         brelse(bh);
412                         break;
413                 }
414
415                 /* OK, we have a valid descriptor block which matches
416                  * all of the sequence number checks.  What are we going
417                  * to do with it?  That depends on the pass... */
418
419                 switch(blocktype) {
420                 case JBD2_DESCRIPTOR_BLOCK:
421                         /* If it is a valid descriptor block, replay it
422                          * in pass REPLAY; otherwise, just skip over the
423                          * blocks it describes. */
424                         if (pass != PASS_REPLAY) {
425                                 next_log_block += count_tags(journal, bh);
426                                 wrap(journal, next_log_block);
427                                 brelse(bh);
428                                 continue;
429                         }
430
431                         /* A descriptor block: we can now write all of
432                          * the data blocks.  Yay, useful work is finally
433                          * getting done here! */
434
435                         tagp = &bh->b_data[sizeof(journal_header_t)];
436                         while ((tagp - bh->b_data + tag_bytes)
437                                <= journal->j_blocksize) {
438                                 unsigned long io_block;
439
440                                 tag = (journal_block_tag_t *) tagp;
441                                 flags = be32_to_cpu(tag->t_flags);
442
443                                 io_block = next_log_block++;
444                                 wrap(journal, next_log_block);
445                                 err = jread(&obh, journal, io_block);
446                                 if (err) {
447                                         /* Recover what we can, but
448                                          * report failure at the end. */
449                                         success = err;
450                                         printk (KERN_ERR
451                                                 "JBD: IO error %d recovering "
452                                                 "block %ld in log\n",
453                                                 err, io_block);
454                                 } else {
455                                         unsigned long long blocknr;
456
457                                         J_ASSERT(obh != NULL);
458                                         blocknr = read_tag_block(tag_bytes,
459                                                                  tag);
460
461                                         /* If the block has been
462                                          * revoked, then we're all done
463                                          * here. */
464                                         if (jbd2_journal_test_revoke
465                                             (journal, blocknr,
466                                              next_commit_ID)) {
467                                                 brelse(obh);
468                                                 ++info->nr_revoke_hits;
469                                                 goto skip_write;
470                                         }
471
472                                         /* Find a buffer for the new
473                                          * data being restored */
474                                         nbh = __getblk(journal->j_fs_dev,
475                                                         blocknr,
476                                                         journal->j_blocksize);
477                                         if (nbh == NULL) {
478                                                 printk(KERN_ERR
479                                                        "JBD: Out of memory "
480                                                        "during recovery.\n");
481                                                 err = -ENOMEM;
482                                                 brelse(bh);
483                                                 brelse(obh);
484                                                 goto failed;
485                                         }
486
487                                         lock_buffer(nbh);
488                                         memcpy(nbh->b_data, obh->b_data,
489                                                         journal->j_blocksize);
490                                         if (flags & JBD2_FLAG_ESCAPE) {
491                                                 *((__be32 *)bh->b_data) =
492                                                 cpu_to_be32(JBD2_MAGIC_NUMBER);
493                                         }
494
495                                         BUFFER_TRACE(nbh, "marking dirty");
496                                         set_buffer_uptodate(nbh);
497                                         mark_buffer_dirty(nbh);
498                                         BUFFER_TRACE(nbh, "marking uptodate");
499                                         ++info->nr_replays;
500                                         /* ll_rw_block(WRITE, 1, &nbh); */
501                                         unlock_buffer(nbh);
502                                         brelse(obh);
503                                         brelse(nbh);
504                                 }
505
506                         skip_write:
507                                 tagp += tag_bytes;
508                                 if (!(flags & JBD2_FLAG_SAME_UUID))
509                                         tagp += 16;
510
511                                 if (flags & JBD2_FLAG_LAST_TAG)
512                                         break;
513                         }
514
515                         brelse(bh);
516                         continue;
517
518                 case JBD2_COMMIT_BLOCK:
519                         /* Found an expected commit block: not much to
520                          * do other than move on to the next sequence
521                          * number. */
522                         brelse(bh);
523                         next_commit_ID++;
524                         continue;
525
526                 case JBD2_REVOKE_BLOCK:
527                         /* If we aren't in the REVOKE pass, then we can
528                          * just skip over this block. */
529                         if (pass != PASS_REVOKE) {
530                                 brelse(bh);
531                                 continue;
532                         }
533
534                         err = scan_revoke_records(journal, bh,
535                                                   next_commit_ID, info);
536                         brelse(bh);
537                         if (err)
538                                 goto failed;
539                         continue;
540
541                 default:
542                         jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
543                                   blocktype);
544                         brelse(bh);
545                         goto done;
546                 }
547         }
548
549  done:
550         /*
551          * We broke out of the log scan loop: either we came to the
552          * known end of the log or we found an unexpected block in the
553          * log.  If the latter happened, then we know that the "current"
554          * transaction marks the end of the valid log.
555          */
556
557         if (pass == PASS_SCAN)
558                 info->end_transaction = next_commit_ID;
559         else {
560                 /* It's really bad news if different passes end up at
561                  * different places (but possible due to IO errors). */
562                 if (info->end_transaction != next_commit_ID) {
563                         printk (KERN_ERR "JBD: recovery pass %d ended at "
564                                 "transaction %u, expected %u\n",
565                                 pass, next_commit_ID, info->end_transaction);
566                         if (!success)
567                                 success = -EIO;
568                 }
569         }
570
571         return success;
572
573  failed:
574         return err;
575 }
576
577
578 /* Scan a revoke record, marking all blocks mentioned as revoked. */
579
580 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
581                                tid_t sequence, struct recovery_info *info)
582 {
583         jbd2_journal_revoke_header_t *header;
584         int offset, max;
585         int record_len = 4;
586
587         header = (jbd2_journal_revoke_header_t *) bh->b_data;
588         offset = sizeof(jbd2_journal_revoke_header_t);
589         max = be32_to_cpu(header->r_count);
590
591         if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
592                 record_len = 8;
593
594         while (offset + record_len <= max) {
595                 unsigned long long blocknr;
596                 int err;
597
598                 if (record_len == 4)
599                         blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
600                 else
601                         blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
602                 offset += record_len;
603                 err = jbd2_journal_set_revoke(journal, blocknr, sequence);
604                 if (err)
605                         return err;
606                 ++info->nr_revokes;
607         }
608         return 0;
609 }