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