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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/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 */
30struct 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
40enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY};
41static int do_one_pass(journal_t *journal,
42 struct recovery_info *info, enum passtype pass);
43static 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 */
49void 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
69static 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
118failed:
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
131static 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
181static int count_tags(struct buffer_head *bh, int size)
182{
183 char * tagp;
184 journal_block_tag_t * tag;
185 int nr = 0;
186
187 tagp = &bh->b_data[sizeof(journal_header_t)];
188
189 while ((tagp - bh->b_data + sizeof(journal_block_tag_t)) <= size) {
190 tag = (journal_block_tag_t *) tagp;
191
192 nr++;
193 tagp += sizeof(journal_block_tag_t);
194 if (!(tag->t_flags & cpu_to_be32(JFS_FLAG_SAME_UUID)))
195 tagp += 16;
196
197 if (tag->t_flags & cpu_to_be32(JFS_FLAG_LAST_TAG))
198 break;
199 }
200
201 return nr;
202}
203
204
205/* Make sure we wrap around the log correctly! */
206#define wrap(journal, var) \
207do { \
208 if (var >= (journal)->j_last) \
209 var -= ((journal)->j_last - (journal)->j_first); \
210} while (0)
211
212/**
Randy Dunlap6c8bec62005-11-07 01:01:04 -0800213 * journal_recover - recovers a on-disk journal
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 * @journal: the journal to recover
215 *
216 * The primary function for recovering the log contents when mounting a
217 * journaled device.
218 *
219 * Recovery is done in three passes. In the first pass, we look for the
220 * end of the log. In the second, we assemble the list of revoke
221 * blocks. In the third and final pass, we replay any un-revoked blocks
222 * in the log.
223 */
224int journal_recover(journal_t *journal)
225{
226 int err;
227 journal_superblock_t * sb;
228
229 struct recovery_info info;
230
231 memset(&info, 0, sizeof(info));
232 sb = journal->j_superblock;
233
234 /*
235 * The journal superblock's s_start field (the current log head)
236 * is always zero if, and only if, the journal was cleanly
237 * unmounted.
238 */
239
240 if (!sb->s_start) {
241 jbd_debug(1, "No recovery required, last transaction %d\n",
242 be32_to_cpu(sb->s_sequence));
243 journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
244 return 0;
245 }
246
247 err = do_one_pass(journal, &info, PASS_SCAN);
248 if (!err)
249 err = do_one_pass(journal, &info, PASS_REVOKE);
250 if (!err)
251 err = do_one_pass(journal, &info, PASS_REPLAY);
252
253 jbd_debug(0, "JBD: recovery, exit status %d, "
254 "recovered transactions %u to %u\n",
255 err, info.start_transaction, info.end_transaction);
256 jbd_debug(0, "JBD: Replayed %d and revoked %d/%d blocks\n",
257 info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
258
259 /* Restart the log at the next transaction ID, thus invalidating
260 * any existing commit records in the log. */
261 journal->j_transaction_sequence = ++info.end_transaction;
262
263 journal_clear_revoke(journal);
264 sync_blockdev(journal->j_fs_dev);
265 return err;
266}
267
268/**
Randy Dunlap6c8bec62005-11-07 01:01:04 -0800269 * journal_skip_recovery - Start journal and wipe exiting records
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270 * @journal: journal to startup
271 *
272 * Locate any valid recovery information from the journal and set up the
273 * journal structures in memory to ignore it (presumably because the
274 * caller has evidence that it is out of date).
275 * This function does'nt appear to be exorted..
276 *
277 * We perform one pass over the journal to allow us to tell the user how
278 * much recovery information is being erased, and to let us initialise
279 * the journal transaction sequence numbers to the next unused ID.
280 */
281int journal_skip_recovery(journal_t *journal)
282{
283 int err;
284 journal_superblock_t * sb;
285
286 struct recovery_info info;
287
288 memset (&info, 0, sizeof(info));
289 sb = journal->j_superblock;
290
291 err = do_one_pass(journal, &info, PASS_SCAN);
292
293 if (err) {
294 printk(KERN_ERR "JBD: error %d scanning journal\n", err);
295 ++journal->j_transaction_sequence;
296 } else {
297#ifdef CONFIG_JBD_DEBUG
298 int dropped = info.end_transaction - be32_to_cpu(sb->s_sequence);
299#endif
300 jbd_debug(0,
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
310static 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 long 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 /* Precompute the maximum metadata descriptors in a descriptor block */
323 int MAX_BLOCKS_PER_DESC;
324 MAX_BLOCKS_PER_DESC = ((journal->j_blocksize-sizeof(journal_header_t))
325 / sizeof(journal_block_tag_t));
326
327 /*
328 * First thing is to establish what we expect to find in the log
329 * (in terms of transaction IDs), and where (in terms of log
330 * block offsets): query the superblock.
331 */
332
333 sb = journal->j_superblock;
334 next_commit_ID = be32_to_cpu(sb->s_sequence);
335 next_log_block = be32_to_cpu(sb->s_start);
336
337 first_commit_ID = next_commit_ID;
338 if (pass == PASS_SCAN)
339 info->start_transaction = first_commit_ID;
340
341 jbd_debug(1, "Starting recovery pass %d\n", pass);
342
343 /*
344 * Now we walk through the log, transaction by transaction,
345 * making sure that each transaction has a commit block in the
346 * expected place. Each complete transaction gets replayed back
347 * into the main filesystem.
348 */
349
350 while (1) {
351 int flags;
352 char * tagp;
353 journal_block_tag_t * tag;
354 struct buffer_head * obh;
355 struct buffer_head * nbh;
356
357 cond_resched(); /* We're under lock_kernel() */
358
359 /* If we already know where to stop the log traversal,
360 * check right now that we haven't gone past the end of
361 * the log. */
362
363 if (pass != PASS_SCAN)
364 if (tid_geq(next_commit_ID, info->end_transaction))
365 break;
366
367 jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
368 next_commit_ID, next_log_block, journal->j_last);
369
370 /* Skip over each chunk of the transaction looking
371 * either the next descriptor block or the final commit
372 * record. */
373
374 jbd_debug(3, "JBD: checking block %ld\n", next_log_block);
375 err = jread(&bh, journal, next_log_block);
376 if (err)
377 goto failed;
378
379 next_log_block++;
380 wrap(journal, next_log_block);
381
382 /* What kind of buffer is it?
383 *
384 * If it is a descriptor block, check that it has the
385 * expected sequence number. Otherwise, we're all done
386 * here. */
387
388 tmp = (journal_header_t *)bh->b_data;
389
390 if (tmp->h_magic != cpu_to_be32(JFS_MAGIC_NUMBER)) {
391 brelse(bh);
392 break;
393 }
394
395 blocktype = be32_to_cpu(tmp->h_blocktype);
396 sequence = be32_to_cpu(tmp->h_sequence);
397 jbd_debug(3, "Found magic %d, sequence %d\n",
398 blocktype, sequence);
399
400 if (sequence != next_commit_ID) {
401 brelse(bh);
402 break;
403 }
404
405 /* OK, we have a valid descriptor block which matches
406 * all of the sequence number checks. What are we going
407 * to do with it? That depends on the pass... */
408
409 switch(blocktype) {
410 case JFS_DESCRIPTOR_BLOCK:
411 /* If it is a valid descriptor block, replay it
412 * in pass REPLAY; otherwise, just skip over the
413 * blocks it describes. */
414 if (pass != PASS_REPLAY) {
415 next_log_block +=
416 count_tags(bh, journal->j_blocksize);
417 wrap(journal, next_log_block);
418 brelse(bh);
419 continue;
420 }
421
422 /* A descriptor block: we can now write all of
423 * the data blocks. Yay, useful work is finally
424 * getting done here! */
425
426 tagp = &bh->b_data[sizeof(journal_header_t)];
427 while ((tagp - bh->b_data +sizeof(journal_block_tag_t))
428 <= journal->j_blocksize) {
429 unsigned long io_block;
430
431 tag = (journal_block_tag_t *) tagp;
432 flags = be32_to_cpu(tag->t_flags);
433
434 io_block = next_log_block++;
435 wrap(journal, next_log_block);
436 err = jread(&obh, journal, io_block);
437 if (err) {
438 /* Recover what we can, but
439 * report failure at the end. */
440 success = err;
441 printk (KERN_ERR
442 "JBD: IO error %d recovering "
443 "block %ld in log\n",
444 err, io_block);
445 } else {
446 unsigned long blocknr;
447
448 J_ASSERT(obh != NULL);
449 blocknr = be32_to_cpu(tag->t_blocknr);
450
451 /* If the block has been
452 * revoked, then we're all done
453 * here. */
454 if (journal_test_revoke
455 (journal, blocknr,
456 next_commit_ID)) {
457 brelse(obh);
458 ++info->nr_revoke_hits;
459 goto skip_write;
460 }
461
462 /* Find a buffer for the new
463 * data being restored */
464 nbh = __getblk(journal->j_fs_dev,
465 blocknr,
466 journal->j_blocksize);
467 if (nbh == NULL) {
468 printk(KERN_ERR
469 "JBD: Out of memory "
470 "during recovery.\n");
471 err = -ENOMEM;
472 brelse(bh);
473 brelse(obh);
474 goto failed;
475 }
476
477 lock_buffer(nbh);
478 memcpy(nbh->b_data, obh->b_data,
479 journal->j_blocksize);
480 if (flags & JFS_FLAG_ESCAPE) {
481 *((__be32 *)bh->b_data) =
482 cpu_to_be32(JFS_MAGIC_NUMBER);
483 }
484
485 BUFFER_TRACE(nbh, "marking dirty");
486 set_buffer_uptodate(nbh);
487 mark_buffer_dirty(nbh);
488 BUFFER_TRACE(nbh, "marking uptodate");
489 ++info->nr_replays;
490 /* ll_rw_block(WRITE, 1, &nbh); */
491 unlock_buffer(nbh);
492 brelse(obh);
493 brelse(nbh);
494 }
495
496 skip_write:
497 tagp += sizeof(journal_block_tag_t);
498 if (!(flags & JFS_FLAG_SAME_UUID))
499 tagp += 16;
500
501 if (flags & JFS_FLAG_LAST_TAG)
502 break;
503 }
504
505 brelse(bh);
506 continue;
507
508 case JFS_COMMIT_BLOCK:
509 /* Found an expected commit block: not much to
510 * do other than move on to the next sequence
511 * number. */
512 brelse(bh);
513 next_commit_ID++;
514 continue;
515
516 case JFS_REVOKE_BLOCK:
517 /* If we aren't in the REVOKE pass, then we can
518 * just skip over this block. */
519 if (pass != PASS_REVOKE) {
520 brelse(bh);
521 continue;
522 }
523
524 err = scan_revoke_records(journal, bh,
525 next_commit_ID, info);
526 brelse(bh);
527 if (err)
528 goto failed;
529 continue;
530
531 default:
532 jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
533 blocktype);
Theodore Ts'oe8f1c622006-06-25 05:47:51 -0700534 brelse(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 goto done;
536 }
537 }
538
539 done:
540 /*
541 * We broke out of the log scan loop: either we came to the
542 * known end of the log or we found an unexpected block in the
543 * log. If the latter happened, then we know that the "current"
544 * transaction marks the end of the valid log.
545 */
546
547 if (pass == PASS_SCAN)
548 info->end_transaction = next_commit_ID;
549 else {
550 /* It's really bad news if different passes end up at
551 * different places (but possible due to IO errors). */
552 if (info->end_transaction != next_commit_ID) {
553 printk (KERN_ERR "JBD: recovery pass %d ended at "
554 "transaction %u, expected %u\n",
555 pass, next_commit_ID, info->end_transaction);
556 if (!success)
557 success = -EIO;
558 }
559 }
560
561 return success;
562
563 failed:
564 return err;
565}
566
567
568/* Scan a revoke record, marking all blocks mentioned as revoked. */
569
570static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
571 tid_t sequence, struct recovery_info *info)
572{
573 journal_revoke_header_t *header;
574 int offset, max;
575
576 header = (journal_revoke_header_t *) bh->b_data;
577 offset = sizeof(journal_revoke_header_t);
578 max = be32_to_cpu(header->r_count);
579
580 while (offset < max) {
581 unsigned long blocknr;
582 int err;
583
584 blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
585 offset += 4;
586 err = journal_set_revoke(journal, blocknr, sequence);
587 if (err)
588 return err;
589 ++info->nr_revokes;
590 }
591 return 0;
592}