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 #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 */
journal_brelse_array(struct buffer_head * b[],int n)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
do_readahead(journal_t * journal,unsigned int start)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 = 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
jread(struct buffer_head ** bhp,journal_t * journal,unsigned int offset)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 = 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
count_tags(journal_t * journal,struct buffer_head * bh)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(JFS_FLAG_SAME_UUID)))
196 tagp += 16;
197
198 if (tag->t_flags & cpu_to_be32(JFS_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 * 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 */
journal_recover(journal_t * journal)225 int 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(1, "JBD: recovery, exit status %d, "
255 "recovered transactions %u to %u\n",
256 err, info.start_transaction, info.end_transaction);
257 jbd_debug(1, "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 journal_clear_revoke(journal);
265 sync_blockdev(journal->j_fs_dev);
266 return err;
267 }
268
269 /**
270 * 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 */
journal_skip_recovery(journal_t * journal)282 int journal_skip_recovery(journal_t *journal)
283 {
284 int err;
285 struct recovery_info info;
286
287 memset (&info, 0, sizeof(info));
288
289 err = do_one_pass(journal, &info, PASS_SCAN);
290
291 if (err) {
292 printk(KERN_ERR "JBD: error %d scanning journal\n", err);
293 ++journal->j_transaction_sequence;
294 } else {
295 #ifdef CONFIG_JBD_DEBUG
296 journal_superblock_t *sb = journal->j_superblock;
297
298 int dropped = info.end_transaction - be32_to_cpu(sb->s_sequence);
299 #endif
300 jbd_debug(1,
301 "JBD: ignoring %d transaction%s from the journal.\n",
302 dropped, (dropped == 1) ? "" : "s");
303 journal->j_transaction_sequence = ++info.end_transaction;
304 }
305
306 journal->j_tail = 0;
307 return err;
308 }
309
read_tag_block(int tag_bytes,journal_block_tag_t * tag)310 static inline unsigned long long read_tag_block(int tag_bytes, journal_block_tag_t *tag)
311 {
312 unsigned long long block = be32_to_cpu(tag->t_blocknr);
313 if (tag_bytes > JBD_TAG_SIZE32)
314 block |= (__u64)be32_to_cpu(tag->t_blocknr_high) << 32;
315 return block;
316 }
317
318 /*
319 * calc_chksums calculates the checksums for the blocks described in the
320 * descriptor block.
321 */
calc_chksums(journal_t * journal,struct buffer_head * bh,unsigned long long * next_log_block,__u32 * crc32_sum)322 static int calc_chksums(journal_t *journal, struct buffer_head *bh,
323 unsigned long long *next_log_block, __u32 *crc32_sum)
324 {
325 int i, num_blks, err;
326 unsigned long long io_block;
327 struct buffer_head *obh;
328
329 num_blks = count_tags(journal, bh);
330 /* Calculate checksum of the descriptor block. */
331 *crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
332
333 for (i = 0; i < num_blks; i++) {
334 io_block = (*next_log_block)++;
335 wrap(journal, *next_log_block);
336 err = jread(&obh, journal, io_block);
337 if (err) {
338 printk(KERN_ERR "JBD: IO error %d recovering block "
339 "%llu in log\n", err, io_block);
340 return 1;
341 } else {
342 *crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
343 obh->b_size);
344 }
345 brelse(obh);
346 }
347 return 0;
348 }
349
do_one_pass(journal_t * journal,struct recovery_info * info,enum passtype pass)350 static int do_one_pass(journal_t *journal,
351 struct recovery_info *info, enum passtype pass)
352 {
353 unsigned int first_commit_ID, next_commit_ID;
354 unsigned long long next_log_block;
355 int err, success = 0;
356 journal_superblock_t * sb;
357 journal_header_t * tmp;
358 struct buffer_head * bh;
359 unsigned int sequence;
360 int blocktype;
361 int tag_bytes = journal_tag_bytes(journal);
362 __u32 crc32_sum = ~0; /* Transactional Checksums */
363
364 /*
365 * First thing is to establish what we expect to find in the log
366 * (in terms of transaction IDs), and where (in terms of log
367 * block offsets): query the superblock.
368 */
369
370 sb = journal->j_superblock;
371 next_commit_ID = be32_to_cpu(sb->s_sequence);
372 next_log_block = be32_to_cpu(sb->s_start);
373
374 first_commit_ID = next_commit_ID;
375 if (pass == PASS_SCAN)
376 info->start_transaction = first_commit_ID;
377
378 jbd_debug(1, "Starting recovery pass %d\n", pass);
379
380 /*
381 * Now we walk through the log, transaction by transaction,
382 * making sure that each transaction has a commit block in the
383 * expected place. Each complete transaction gets replayed back
384 * into the main filesystem.
385 */
386
387 while (1) {
388 int flags;
389 char * tagp;
390 journal_block_tag_t * tag;
391 struct buffer_head * obh;
392 struct buffer_head * nbh;
393
394 cond_resched();
395
396 /* If we already know where to stop the log traversal,
397 * check right now that we haven't gone past the end of
398 * the log. */
399
400 if (pass != PASS_SCAN)
401 if (tid_geq(next_commit_ID, info->end_transaction))
402 break;
403
404 jbd_debug(2, "Scanning for sequence ID %u at %llu/%lu\n",
405 next_commit_ID, next_log_block, journal->j_last);
406
407 /* Skip over each chunk of the transaction looking
408 * either the next descriptor block or the final commit
409 * record. */
410
411 jbd_debug(3, "JBD: checking block %llu\n", next_log_block);
412 err = jread(&bh, journal, next_log_block);
413 if (err)
414 goto failed;
415
416 next_log_block++;
417 wrap(journal, next_log_block);
418
419 /* What kind of buffer is it?
420 *
421 * If it is a descriptor block, check that it has the
422 * expected sequence number. Otherwise, we're all done
423 * here. */
424
425 tmp = (journal_header_t *)bh->b_data;
426
427 if (tmp->h_magic != cpu_to_be32(JFS_MAGIC_NUMBER)) {
428 brelse(bh);
429 break;
430 }
431
432 blocktype = be32_to_cpu(tmp->h_blocktype);
433 sequence = be32_to_cpu(tmp->h_sequence);
434 jbd_debug(3, "Found magic %d, sequence %d\n",
435 blocktype, sequence);
436
437 if (sequence != next_commit_ID) {
438 brelse(bh);
439 break;
440 }
441
442 /* OK, we have a valid descriptor block which matches
443 * all of the sequence number checks. What are we going
444 * to do with it? That depends on the pass... */
445
446 switch(blocktype) {
447 case JFS_DESCRIPTOR_BLOCK:
448 /* If it is a valid descriptor block, replay it
449 * in pass REPLAY; if journal_checksums enabled, then
450 * calculate checksums in PASS_SCAN, otherwise,
451 * just skip over the blocks it describes. */
452 if (pass != PASS_REPLAY) {
453 if (pass == PASS_SCAN &&
454 JFS_HAS_COMPAT_FEATURE(journal,
455 JFS_FEATURE_COMPAT_CHECKSUM) &&
456 !info->end_transaction) {
457 if (calc_chksums(journal, bh,
458 &next_log_block,
459 &crc32_sum)) {
460 brelse(bh);
461 break;
462 }
463 brelse(bh);
464 continue;
465 }
466 next_log_block += count_tags(journal, bh);
467 wrap(journal, next_log_block);
468 brelse(bh);
469 continue;
470 }
471
472 /* A descriptor block: we can now write all of
473 * the data blocks. Yay, useful work is finally
474 * getting done here! */
475
476 tagp = &bh->b_data[sizeof(journal_header_t)];
477 while ((tagp - bh->b_data + tag_bytes)
478 <= journal->j_blocksize) {
479 unsigned long long io_block;
480
481 tag = (journal_block_tag_t *) tagp;
482 flags = be32_to_cpu(tag->t_flags);
483
484 io_block = next_log_block++;
485 wrap(journal, next_log_block);
486 err = jread(&obh, journal, io_block);
487 if (err) {
488 /* Recover what we can, but
489 * report failure at the end. */
490 success = err;
491 printk (KERN_ERR
492 "JBD: IO error %d recovering "
493 "block %llu in log\n",
494 err, io_block);
495 } else {
496 unsigned long long blocknr;
497
498 J_ASSERT(obh != NULL);
499 blocknr = read_tag_block(tag_bytes,
500 tag);
501
502 /* If the block has been
503 * revoked, then we're all done
504 * here. */
505 if (journal_test_revoke
506 (journal, blocknr,
507 next_commit_ID)) {
508 brelse(obh);
509 ++info->nr_revoke_hits;
510 goto skip_write;
511 }
512
513 /* Find a buffer for the new
514 * data being restored */
515 nbh = __getblk(journal->j_fs_dev,
516 blocknr,
517 journal->j_blocksize);
518 if (nbh == NULL) {
519 printk(KERN_ERR
520 "JBD: Out of memory "
521 "during recovery.\n");
522 err = -ENOMEM;
523 brelse(bh);
524 brelse(obh);
525 goto failed;
526 }
527
528 lock_buffer(nbh);
529 memcpy(nbh->b_data, obh->b_data,
530 journal->j_blocksize);
531 if (flags & JFS_FLAG_ESCAPE) {
532 journal_header_t *header;
533
534 header = (journal_header_t *) &nbh->b_data[0];
535 header->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER);
536 }
537
538 BUFFER_TRACE(nbh, "marking dirty");
539 set_buffer_uptodate(nbh);
540 mark_buffer_dirty(nbh);
541 BUFFER_TRACE(nbh, "marking uptodate");
542 ++info->nr_replays;
543 /* ll_rw_block(WRITE, 1, &nbh); */
544 unlock_buffer(nbh);
545 brelse(obh);
546 brelse(nbh);
547 }
548
549 skip_write:
550 tagp += tag_bytes;
551 if (!(flags & JFS_FLAG_SAME_UUID))
552 tagp += 16;
553
554 if (flags & JFS_FLAG_LAST_TAG)
555 break;
556 }
557
558 brelse(bh);
559 continue;
560
561 case JFS_COMMIT_BLOCK:
562 jbd_debug(3, "Commit block for #%u found\n",
563 next_commit_ID);
564 /* How to differentiate between interrupted commit
565 * and journal corruption ?
566 *
567 * {nth transaction}
568 * Checksum Verification Failed
569 * |
570 * ____________________
571 * | |
572 * async_commit sync_commit
573 * | |
574 * | GO TO NEXT "Journal Corruption"
575 * | TRANSACTION
576 * |
577 * {(n+1)th transanction}
578 * |
579 * _______|______________
580 * | |
581 * Commit block found Commit block not found
582 * | |
583 * "Journal Corruption" |
584 * _____________|_________
585 * | |
586 * nth trans corrupt OR nth trans
587 * and (n+1)th interrupted interrupted
588 * before commit block
589 * could reach the disk.
590 * (Cannot find the difference in above
591 * mentioned conditions. Hence assume
592 * "Interrupted Commit".)
593 */
594
595 /* Found an expected commit block: if checksums
596 * are present verify them in PASS_SCAN; else not
597 * much to do other than move on to the next sequence
598 * number. */
599 if (pass == PASS_SCAN &&
600 JFS_HAS_COMPAT_FEATURE(journal,
601 JFS_FEATURE_COMPAT_CHECKSUM)) {
602 int chksum_err, chksum_seen;
603 struct commit_header *cbh =
604 (struct commit_header *)bh->b_data;
605 unsigned found_chksum =
606 be32_to_cpu(cbh->h_chksum[0]);
607
608 chksum_err = chksum_seen = 0;
609
610 jbd_debug(3, "Checksums %x %x\n",
611 crc32_sum, found_chksum);
612 if (info->end_transaction) {
613 journal->j_failed_commit =
614 info->end_transaction;
615 brelse(bh);
616 break;
617 }
618
619 if (crc32_sum == found_chksum &&
620 cbh->h_chksum_type == JBD2_CRC32_CHKSUM &&
621 cbh->h_chksum_size ==
622 JBD2_CRC32_CHKSUM_SIZE)
623 chksum_seen = 1;
624 else if (!(cbh->h_chksum_type == 0 &&
625 cbh->h_chksum_size == 0 &&
626 found_chksum == 0 &&
627 !chksum_seen))
628 /*
629 * If fs is mounted using an old kernel and then
630 * kernel with journal_chksum is used then we
631 * get a situation where the journal flag has
632 * checksum flag set but checksums are not
633 * present i.e chksum = 0, in the individual
634 * commit blocks.
635 * Hence to avoid checksum failures, in this
636 * situation, this extra check is added.
637 */
638 chksum_err = 1;
639
640 if (chksum_err) {
641 info->end_transaction = next_commit_ID;
642 jbd_debug(1, "Checksum_err %x %x\n",
643 crc32_sum, found_chksum);
644 if (!JFS_HAS_INCOMPAT_FEATURE(journal,
645 JFS_FEATURE_INCOMPAT_ASYNC_COMMIT)){
646 journal->j_failed_commit =
647 next_commit_ID;
648 brelse(bh);
649 break;
650 }
651 }
652 crc32_sum = ~0;
653 }
654 brelse(bh);
655 next_commit_ID++;
656 continue;
657
658 case JFS_REVOKE_BLOCK:
659 /* If we aren't in the REVOKE pass, then we can
660 * just skip over this block. */
661 if (pass != PASS_REVOKE) {
662 brelse(bh);
663 continue;
664 }
665
666 err = scan_revoke_records(journal, bh,
667 next_commit_ID, info);
668 brelse(bh);
669 if (err)
670 goto failed;
671 continue;
672
673 default:
674 jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
675 blocktype);
676 brelse(bh);
677 goto done;
678 }
679 }
680
681 done:
682 /*
683 * We broke out of the log scan loop: either we came to the
684 * known end of the log or we found an unexpected block in the
685 * log. If the latter happened, then we know that the "current"
686 * transaction marks the end of the valid log.
687 */
688
689 if (pass == PASS_SCAN) {
690 if (!info->end_transaction)
691 info->end_transaction = next_commit_ID;
692 } else {
693 /* It's really bad news if different passes end up at
694 * different places (but possible due to IO errors). */
695 if (info->end_transaction != next_commit_ID) {
696 printk (KERN_ERR "JBD: recovery pass %d ended at "
697 "transaction %u, expected %u\n",
698 pass, next_commit_ID, info->end_transaction);
699 if (!success)
700 success = -EIO;
701 }
702 }
703
704 return success;
705
706 failed:
707 return err;
708 }
709
710
711 /* Scan a revoke record, marking all blocks mentioned as revoked. */
712
scan_revoke_records(journal_t * journal,struct buffer_head * bh,tid_t sequence,struct recovery_info * info)713 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
714 tid_t sequence, struct recovery_info *info)
715 {
716 journal_revoke_header_t *header;
717 int offset, max;
718 int record_len = 4;
719
720 header = (journal_revoke_header_t *) bh->b_data;
721 offset = sizeof(journal_revoke_header_t);
722 max = be32_to_cpu(header->r_count);
723
724 if (JFS_HAS_INCOMPAT_FEATURE(journal, JFS_FEATURE_INCOMPAT_64BIT))
725 record_len = 8;
726
727 while (offset < max) {
728 unsigned long long blocknr;
729 int err;
730
731 if (record_len == 4) {
732 __be32 b;
733 memcpy(&b, bh->b_data + offset, sizeof(__be32));
734 blocknr = ext2fs_be32_to_cpu(b);
735 } else {
736 __be64 b;
737 memcpy(&b, bh->b_data + offset, sizeof(__be64));
738 blocknr = ext2fs_be64_to_cpu(b);
739 }
740
741 offset += record_len;
742 err = journal_set_revoke(journal, blocknr, sequence);
743 if (err)
744 return err;
745 ++info->nr_revokes;
746 }
747 return 0;
748 }
749