Line data Source code
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 1 :
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 0 : while (--n >= 0)
52 0 : brelse (b[n]);
53 0 : }
54 0 :
55 :
56 : /*
57 : * When reading from the journal, we are going through the block device
58 0 : * 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 0 : int err;
72 0 : unsigned int max, nbufs, next;
73 0 : unsigned int blocknr;
74 0 : struct buffer_head *bh;
75 0 :
76 0 : struct buffer_head * bufs[MAXBUF];
77 0 :
78 0 : /* Do up to 128K of readahead */
79 0 : max = start + (128 * 1024 / journal->j_blocksize);
80 0 : if (max > journal->j_maxlen)
81 0 : 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 0 : nbufs = 0;
87 :
88 0 : for (next = start; next < max; next++) {
89 0 : err = journal_bmap(journal, next, &blocknr);
90 0 :
91 0 : if (err) {
92 0 : printk (KERN_ERR "JBD: bad block at offset %u\n",
93 : next);
94 0 : goto failed;
95 : }
96 :
97 0 : bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
98 0 : if (!bh) {
99 0 : err = -ENOMEM;
100 0 : goto failed;
101 : }
102 :
103 0 : if (!buffer_uptodate(bh) && !buffer_locked(bh)) {
104 0 : bufs[nbufs++] = bh;
105 0 : if (nbufs == MAXBUF) {
106 0 : ll_rw_block(READ, nbufs, bufs);
107 0 : journal_brelse_array(bufs, nbufs);
108 0 : nbufs = 0;
109 : }
110 : } else
111 0 : brelse(bh);
112 : }
113 :
114 0 : if (nbufs)
115 0 : ll_rw_block(READ, nbufs, bufs);
116 0 : err = 0;
117 0 :
118 : failed:
119 0 : if (nbufs)
120 0 : journal_brelse_array(bufs, nbufs);
121 0 : 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 0 : {
134 0 : int err;
135 0 : unsigned int blocknr;
136 0 : struct buffer_head *bh;
137 0 :
138 0 : *bhp = NULL;
139 :
140 0 : if (offset >= journal->j_maxlen) {
141 0 : printk(KERN_ERR "JBD: corrupted journal superblock\n");
142 0 : return -EIO;
143 : }
144 :
145 0 : err = journal_bmap(journal, offset, &blocknr);
146 :
147 0 : if (err) {
148 0 : printk (KERN_ERR "JBD: bad block at offset %u\n",
149 : offset);
150 0 : return err;
151 : }
152 :
153 0 : bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
154 0 : if (!bh)
155 0 : return -ENOMEM;
156 :
157 0 : if (!buffer_uptodate(bh)) {
158 : /* If this is a brand new buffer, start readahead.
159 : Otherwise, we assume we are already reading it. */
160 0 : if (!buffer_req(bh))
161 0 : do_readahead(journal, offset);
162 0 : wait_on_buffer(bh);
163 : }
164 :
165 0 : if (!buffer_uptodate(bh)) {
166 0 : printk (KERN_ERR "JBD: Failed to read block at offset %u\n",
167 : offset);
168 0 : brelse(bh);
169 0 : return -EIO;
170 : }
171 :
172 0 : *bhp = bh;
173 0 : 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(struct buffer_head *bh, int size)
182 : {
183 0 : char * tagp;
184 0 : journal_block_tag_t * tag;
185 0 : int nr = 0;
186 :
187 0 : tagp = &bh->b_data[sizeof(journal_header_t)];
188 :
189 0 : while ((tagp - bh->b_data + sizeof(journal_block_tag_t)) <= size) {
190 0 : tag = (journal_block_tag_t *) tagp;
191 0 :
192 0 : nr++;
193 0 : tagp += sizeof(journal_block_tag_t);
194 0 : if (!(tag->t_flags & cpu_to_be32(JFS_FLAG_SAME_UUID)))
195 0 : tagp += 16;
196 :
197 0 : if (tag->t_flags & cpu_to_be32(JFS_FLAG_LAST_TAG))
198 0 : break;
199 : }
200 :
201 0 : return nr;
202 0 : }
203 :
204 :
205 : /* Make sure we wrap around the log correctly! */
206 : #define wrap(journal, var) \
207 : do { \
208 : if (var >= (journal)->j_last) \
209 : var -= ((journal)->j_last - (journal)->j_first); \
210 : } while (0)
211 :
212 : /**
213 : * journal_recover - recovers a on-disk journal
214 : * @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 : */
224 : int journal_recover(journal_t *journal)
225 : {
226 0 : int err, err2;
227 0 : journal_superblock_t * sb;
228 0 :
229 0 : struct recovery_info info;
230 0 :
231 0 : memset(&info, 0, sizeof(info));
232 0 : 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 0 : if (!sb->s_start) {
241 : jbd_debug(1, "No recovery required, last transaction %d\n",
242 : be32_to_cpu(sb->s_sequence));
243 0 : journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
244 0 : return 0;
245 : }
246 :
247 0 : err = do_one_pass(journal, &info, PASS_SCAN);
248 0 : if (!err)
249 0 : err = do_one_pass(journal, &info, PASS_REVOKE);
250 0 : if (!err)
251 0 : err = do_one_pass(journal, &info, PASS_REPLAY);
252 :
253 : jbd_debug(1, "JBD: recovery, exit status %d, "
254 : "recovered transactions %u to %u\n",
255 : err, info.start_transaction, info.end_transaction);
256 : jbd_debug(1, "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 0 : journal->j_transaction_sequence = ++info.end_transaction;
262 :
263 0 : journal_clear_revoke(journal);
264 0 : err2 = sync_blockdev(journal->j_fs_dev);
265 0 : if (!err)
266 0 : err = err2;
267 :
268 0 : return err;
269 : }
270 :
271 : /**
272 : * journal_skip_recovery - Start journal and wipe exiting records
273 : * @journal: journal to startup
274 : *
275 : * Locate any valid recovery information from the journal and set up the
276 : * journal structures in memory to ignore it (presumably because the
277 : * caller has evidence that it is out of date).
278 : * This function does'nt appear to be exorted..
279 : *
280 : * We perform one pass over the journal to allow us to tell the user how
281 : * much recovery information is being erased, and to let us initialise
282 : * the journal transaction sequence numbers to the next unused ID.
283 : */
284 : int journal_skip_recovery(journal_t *journal)
285 : {
286 0 : int err;
287 0 : journal_superblock_t * sb;
288 0 :
289 : struct recovery_info info;
290 :
291 0 : memset (&info, 0, sizeof(info));
292 0 : sb = journal->j_superblock;
293 :
294 0 : err = do_one_pass(journal, &info, PASS_SCAN);
295 :
296 0 : if (err) {
297 0 : printk(KERN_ERR "JBD: error %d scanning journal\n", err);
298 0 : ++journal->j_transaction_sequence;
299 : } else {
300 : #ifdef CONFIG_JBD_DEBUG
301 : int dropped = info.end_transaction - be32_to_cpu(sb->s_sequence);
302 : #endif
303 : jbd_debug(1,
304 : "JBD: ignoring %d transaction%s from the journal.\n",
305 : dropped, (dropped == 1) ? "" : "s");
306 0 : journal->j_transaction_sequence = ++info.end_transaction;
307 : }
308 :
309 0 : journal->j_tail = 0;
310 0 : return err;
311 : }
312 :
313 : static int do_one_pass(journal_t *journal,
314 : struct recovery_info *info, enum passtype pass)
315 0 : {
316 0 : unsigned int first_commit_ID, next_commit_ID;
317 0 : unsigned int next_log_block;
318 0 : int err, success = 0;
319 0 : journal_superblock_t * sb;
320 0 : journal_header_t * tmp;
321 0 : struct buffer_head * bh;
322 0 : unsigned int sequence;
323 0 : int blocktype;
324 0 :
325 0 : /* Precompute the maximum metadata descriptors in a descriptor block */
326 0 : int MAX_BLOCKS_PER_DESC;
327 0 : MAX_BLOCKS_PER_DESC = ((journal->j_blocksize-sizeof(journal_header_t))
328 0 : / sizeof(journal_block_tag_t));
329 0 :
330 0 : /*
331 0 : * First thing is to establish what we expect to find in the log
332 0 : * (in terms of transaction IDs), and where (in terms of log
333 0 : * block offsets): query the superblock.
334 0 : */
335 0 :
336 0 : sb = journal->j_superblock;
337 0 : next_commit_ID = be32_to_cpu(sb->s_sequence);
338 0 : next_log_block = be32_to_cpu(sb->s_start);
339 0 :
340 0 : first_commit_ID = next_commit_ID;
341 0 : if (pass == PASS_SCAN)
342 0 : info->start_transaction = first_commit_ID;
343 0 :
344 : jbd_debug(1, "Starting recovery pass %d\n", pass);
345 :
346 0 : /*
347 : * Now we walk through the log, transaction by transaction,
348 : * making sure that each transaction has a commit block in the
349 : * expected place. Each complete transaction gets replayed back
350 : * into the main filesystem.
351 : */
352 :
353 : while (1) {
354 : int flags;
355 : char * tagp;
356 : journal_block_tag_t * tag;
357 : struct buffer_head * obh;
358 : struct buffer_head * nbh;
359 :
360 0 : cond_resched();
361 :
362 : /* If we already know where to stop the log traversal,
363 : * check right now that we haven't gone past the end of
364 : * the log. */
365 :
366 0 : if (pass != PASS_SCAN)
367 0 : if (tid_geq(next_commit_ID, info->end_transaction))
368 0 : break;
369 :
370 : jbd_debug(2, "Scanning for sequence ID %u at %u/%u\n",
371 : next_commit_ID, next_log_block, journal->j_last);
372 :
373 : /* Skip over each chunk of the transaction looking
374 : * either the next descriptor block or the final commit
375 : * record. */
376 :
377 : jbd_debug(3, "JBD: checking block %u\n", next_log_block);
378 0 : err = jread(&bh, journal, next_log_block);
379 0 : if (err)
380 0 : goto failed;
381 :
382 0 : next_log_block++;
383 0 : wrap(journal, next_log_block);
384 :
385 : /* What kind of buffer is it?
386 : *
387 : * If it is a descriptor block, check that it has the
388 : * expected sequence number. Otherwise, we're all done
389 : * here. */
390 :
391 0 : tmp = (journal_header_t *)bh->b_data;
392 :
393 0 : if (tmp->h_magic != cpu_to_be32(JFS_MAGIC_NUMBER)) {
394 0 : brelse(bh);
395 0 : break;
396 : }
397 :
398 0 : blocktype = be32_to_cpu(tmp->h_blocktype);
399 0 : sequence = be32_to_cpu(tmp->h_sequence);
400 : jbd_debug(3, "Found magic %d, sequence %d\n",
401 : blocktype, sequence);
402 :
403 0 : if (sequence != next_commit_ID) {
404 0 : brelse(bh);
405 0 : break;
406 : }
407 :
408 : /* OK, we have a valid descriptor block which matches
409 : * all of the sequence number checks. What are we going
410 : * to do with it? That depends on the pass... */
411 :
412 : switch(blocktype) {
413 0 : case JFS_DESCRIPTOR_BLOCK:
414 : /* If it is a valid descriptor block, replay it
415 : * in pass REPLAY; otherwise, just skip over the
416 : * blocks it describes. */
417 0 : if (pass != PASS_REPLAY) {
418 0 : next_log_block +=
419 : count_tags(bh, journal->j_blocksize);
420 0 : wrap(journal, next_log_block);
421 0 : brelse(bh);
422 0 : continue;
423 : }
424 :
425 : /* A descriptor block: we can now write all of
426 : * the data blocks. Yay, useful work is finally
427 : * getting done here! */
428 :
429 0 : tagp = &bh->b_data[sizeof(journal_header_t)];
430 0 : while ((tagp - bh->b_data +sizeof(journal_block_tag_t))
431 0 : <= journal->j_blocksize) {
432 : unsigned int io_block;
433 0 :
434 0 : tag = (journal_block_tag_t *) tagp;
435 0 : flags = be32_to_cpu(tag->t_flags);
436 :
437 0 : io_block = next_log_block++;
438 0 : wrap(journal, next_log_block);
439 0 : err = jread(&obh, journal, io_block);
440 0 : if (err) {
441 : /* Recover what we can, but
442 : * report failure at the end. */
443 0 : success = err;
444 0 : printk (KERN_ERR
445 : "JBD: IO error %d recovering "
446 : "block %u in log\n",
447 : err, io_block);
448 : } else {
449 : unsigned int blocknr;
450 :
451 0 : J_ASSERT(obh != NULL);
452 0 : blocknr = be32_to_cpu(tag->t_blocknr);
453 :
454 : /* If the block has been
455 : * revoked, then we're all done
456 : * here. */
457 0 : if (journal_test_revoke
458 : (journal, blocknr,
459 : next_commit_ID)) {
460 0 : brelse(obh);
461 0 : ++info->nr_revoke_hits;
462 0 : goto skip_write;
463 : }
464 :
465 : /* Find a buffer for the new
466 : * data being restored */
467 0 : nbh = __getblk(journal->j_fs_dev,
468 : blocknr,
469 : journal->j_blocksize);
470 0 : if (nbh == NULL) {
471 0 : printk(KERN_ERR
472 : "JBD: Out of memory "
473 : "during recovery.\n");
474 0 : err = -ENOMEM;
475 0 : brelse(bh);
476 0 : brelse(obh);
477 0 : goto failed;
478 : }
479 :
480 0 : lock_buffer(nbh);
481 0 : memcpy(nbh->b_data, obh->b_data,
482 : journal->j_blocksize);
483 0 : if (flags & JFS_FLAG_ESCAPE) {
484 0 : *((__be32 *)nbh->b_data) =
485 : cpu_to_be32(JFS_MAGIC_NUMBER);
486 : }
487 :
488 : BUFFER_TRACE(nbh, "marking dirty");
489 0 : set_buffer_uptodate(nbh);
490 0 : mark_buffer_dirty(nbh);
491 : BUFFER_TRACE(nbh, "marking uptodate");
492 0 : ++info->nr_replays;
493 : /* ll_rw_block(WRITE, 1, &nbh); */
494 0 : unlock_buffer(nbh);
495 0 : brelse(obh);
496 0 : brelse(nbh);
497 : }
498 :
499 0 : skip_write:
500 0 : tagp += sizeof(journal_block_tag_t);
501 0 : if (!(flags & JFS_FLAG_SAME_UUID))
502 0 : tagp += 16;
503 :
504 0 : if (flags & JFS_FLAG_LAST_TAG)
505 0 : break;
506 : }
507 :
508 0 : brelse(bh);
509 0 : continue;
510 0 :
511 0 : case JFS_COMMIT_BLOCK:
512 : /* Found an expected commit block: not much to
513 : * do other than move on to the next sequence
514 : * number. */
515 0 : brelse(bh);
516 0 : next_commit_ID++;
517 0 : continue;
518 0 :
519 0 : case JFS_REVOKE_BLOCK:
520 : /* If we aren't in the REVOKE pass, then we can
521 : * just skip over this block. */
522 0 : if (pass != PASS_REVOKE) {
523 0 : brelse(bh);
524 0 : continue;
525 : }
526 :
527 0 : err = scan_revoke_records(journal, bh,
528 : next_commit_ID, info);
529 0 : brelse(bh);
530 0 : if (err)
531 0 : goto failed;
532 0 : continue;
533 0 :
534 0 : default:
535 0 : jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
536 : blocktype);
537 0 : brelse(bh);
538 0 : goto done;
539 : }
540 0 : }
541 0 :
542 0 : done:
543 : /*
544 : * We broke out of the log scan loop: either we came to the
545 : * known end of the log or we found an unexpected block in the
546 : * log. If the latter happened, then we know that the "current"
547 : * transaction marks the end of the valid log.
548 : */
549 :
550 0 : if (pass == PASS_SCAN)
551 0 : info->end_transaction = next_commit_ID;
552 : else {
553 : /* It's really bad news if different passes end up at
554 : * different places (but possible due to IO errors). */
555 0 : if (info->end_transaction != next_commit_ID) {
556 0 : printk (KERN_ERR "JBD: recovery pass %d ended at "
557 : "transaction %u, expected %u\n",
558 : pass, next_commit_ID, info->end_transaction);
559 0 : if (!success)
560 0 : success = -EIO;
561 : }
562 : }
563 :
564 0 : return success;
565 0 :
566 : failed:
567 0 : return err;
568 : }
569 :
570 :
571 : /* Scan a revoke record, marking all blocks mentioned as revoked. */
572 :
573 : static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
574 : tid_t sequence, struct recovery_info *info)
575 : {
576 0 : journal_revoke_header_t *header;
577 0 : int offset, max;
578 0 :
579 0 : header = (journal_revoke_header_t *) bh->b_data;
580 0 : offset = sizeof(journal_revoke_header_t);
581 0 : max = be32_to_cpu(header->r_count);
582 0 :
583 0 : while (offset < max) {
584 0 : unsigned int blocknr;
585 0 : int err;
586 :
587 0 : blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
588 0 : offset += 4;
589 0 : err = journal_set_revoke(journal, blocknr, sequence);
590 0 : if (err)
591 0 : return err;
592 0 : ++info->nr_revokes;
593 0 : }
594 0 : return 0;
595 : }
|