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 */
journal_brelse_array(struct buffer_head * b[],int n)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
do_readahead(journal_t * journal,unsigned int start)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
jread(struct buffer_head ** bhp,journal_t * journal,unsigned int offset)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
count_tags(journal_t * journal,struct buffer_head * bh)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 */
jbd2_journal_recover(journal_t * journal)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 */
jbd2_journal_skip_recovery(journal_t * journal)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
read_tag_block(int tag_bytes,journal_block_tag_t * tag)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 */
calc_chksums(journal_t * journal,struct buffer_head * bh,unsigned long * next_log_block,__u32 * crc32_sum)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
do_one_pass(journal_t * journal,struct recovery_info * info,enum passtype pass)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
scan_revoke_records(journal_t * journal,struct buffer_head * bh,tid_t sequence,struct recovery_info * info)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 }
746