ACPI: thinkpad-acpi: keep track of module state
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / jbd2 / recovery.c
blobb50be8a044eb8d8bb8849bedc662d516bfa971bb
1 /*
2 * linux/fs/jbd2/recovery.c
4 * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
6 * Copyright 1999-2000 Red Hat Software --- All Rights Reserved
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.
12 * Journal recovery routines for the generic filesystem journaling code;
13 * part of the ext2fs journaling system.
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 #endif
27 * Maintain information about the progress of the recovery job, so that
28 * the different passes can carry information between them.
30 struct recovery_info
32 tid_t start_transaction;
33 tid_t end_transaction;
35 int nr_replays;
36 int nr_revokes;
37 int nr_revoke_hits;
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 *);
46 #ifdef __KERNEL__
48 /* Release readahead buffers after use */
49 static void journal_brelse_array(struct buffer_head *b[], int n)
51 while (--n >= 0)
52 brelse (b[n]);
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.
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.
68 #define MAXBUF 8
69 static int do_readahead(journal_t *journal, unsigned int start)
71 int err;
72 unsigned int max, nbufs, next;
73 unsigned long long blocknr;
74 struct buffer_head *bh;
76 struct buffer_head * bufs[MAXBUF];
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;
83 /* Do the readahead itself. We'll submit MAXBUF buffer_heads at
84 * a time to the block device IO layer. */
86 nbufs = 0;
88 for (next = start; next < max; next++) {
89 err = jbd2_journal_bmap(journal, next, &blocknr);
91 if (err) {
92 printk (KERN_ERR "JBD: bad block at offset %u\n",
93 next);
94 goto failed;
97 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
98 if (!bh) {
99 err = -ENOMEM;
100 goto failed;
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;
110 } else
111 brelse(bh);
114 if (nbufs)
115 ll_rw_block(READ, nbufs, bufs);
116 err = 0;
118 failed:
119 if (nbufs)
120 journal_brelse_array(bufs, nbufs);
121 return err;
124 #endif /* __KERNEL__ */
128 * Read a block from the journal
131 static int jread(struct buffer_head **bhp, journal_t *journal,
132 unsigned int offset)
134 int err;
135 unsigned long long blocknr;
136 struct buffer_head *bh;
138 *bhp = NULL;
140 if (offset >= journal->j_maxlen) {
141 printk(KERN_ERR "JBD: corrupted journal superblock\n");
142 return -EIO;
145 err = jbd2_journal_bmap(journal, offset, &blocknr);
147 if (err) {
148 printk (KERN_ERR "JBD: bad block at offset %u\n",
149 offset);
150 return err;
153 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
154 if (!bh)
155 return -ENOMEM;
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);
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;
172 *bhp = bh;
173 return 0;
178 * Count the number of in-use tags in a journal descriptor block.
181 static int count_tags(journal_t *journal, struct buffer_head *bh)
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);
188 tagp = &bh->b_data[sizeof(journal_header_t)];
190 while ((tagp - bh->b_data + tag_bytes) <= size) {
191 tag = (journal_block_tag_t *) tagp;
193 nr++;
194 tagp += tag_bytes;
195 if (!(tag->t_flags & cpu_to_be32(JBD2_FLAG_SAME_UUID)))
196 tagp += 16;
198 if (tag->t_flags & cpu_to_be32(JBD2_FLAG_LAST_TAG))
199 break;
202 return nr;
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)
214 * jbd2_journal_recover - recovers a on-disk journal
215 * @journal: the journal to recover
217 * The primary function for recovering the log contents when mounting a
218 * journaled device.
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.
225 int jbd2_journal_recover(journal_t *journal)
227 int err;
228 journal_superblock_t * sb;
230 struct recovery_info info;
232 memset(&info, 0, sizeof(info));
233 sb = journal->j_superblock;
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.
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;
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);
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);
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;
264 jbd2_journal_clear_revoke(journal);
265 sync_blockdev(journal->j_fs_dev);
266 return err;
270 * jbd2_journal_skip_recovery - Start journal and wipe exiting records
271 * @journal: journal to startup
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..
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.
282 int jbd2_journal_skip_recovery(journal_t *journal)
284 int err;
285 journal_superblock_t * sb;
287 struct recovery_info info;
289 memset (&info, 0, sizeof(info));
290 sb = journal->j_superblock;
292 err = do_one_pass(journal, &info, PASS_SCAN);
294 if (err) {
295 printk(KERN_ERR "JBD: error %d scanning journal\n", err);
296 ++journal->j_transaction_sequence;
297 } else {
298 #ifdef CONFIG_JBD2_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;
307 journal->j_tail = 0;
308 return err;
311 static inline unsigned long long read_tag_block(int tag_bytes, journal_block_tag_t *tag)
313 unsigned long long block = be32_to_cpu(tag->t_blocknr);
314 if (tag_bytes > JBD_TAG_SIZE32)
315 block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
316 return block;
319 static int do_one_pass(journal_t *journal,
320 struct recovery_info *info, enum passtype pass)
322 unsigned int first_commit_ID, next_commit_ID;
323 unsigned long next_log_block;
324 int err, success = 0;
325 journal_superblock_t * sb;
326 journal_header_t * tmp;
327 struct buffer_head * bh;
328 unsigned int sequence;
329 int blocktype;
330 int tag_bytes = journal_tag_bytes(journal);
332 /* Precompute the maximum metadata descriptors in a descriptor block */
333 int MAX_BLOCKS_PER_DESC;
334 MAX_BLOCKS_PER_DESC = ((journal->j_blocksize-sizeof(journal_header_t))
335 / tag_bytes);
338 * First thing is to establish what we expect to find in the log
339 * (in terms of transaction IDs), and where (in terms of log
340 * block offsets): query the superblock.
343 sb = journal->j_superblock;
344 next_commit_ID = be32_to_cpu(sb->s_sequence);
345 next_log_block = be32_to_cpu(sb->s_start);
347 first_commit_ID = next_commit_ID;
348 if (pass == PASS_SCAN)
349 info->start_transaction = first_commit_ID;
351 jbd_debug(1, "Starting recovery pass %d\n", pass);
354 * Now we walk through the log, transaction by transaction,
355 * making sure that each transaction has a commit block in the
356 * expected place. Each complete transaction gets replayed back
357 * into the main filesystem.
360 while (1) {
361 int flags;
362 char * tagp;
363 journal_block_tag_t * tag;
364 struct buffer_head * obh;
365 struct buffer_head * nbh;
367 cond_resched(); /* We're under lock_kernel() */
369 /* If we already know where to stop the log traversal,
370 * check right now that we haven't gone past the end of
371 * the log. */
373 if (pass != PASS_SCAN)
374 if (tid_geq(next_commit_ID, info->end_transaction))
375 break;
377 jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
378 next_commit_ID, next_log_block, journal->j_last);
380 /* Skip over each chunk of the transaction looking
381 * either the next descriptor block or the final commit
382 * record. */
384 jbd_debug(3, "JBD: checking block %ld\n", next_log_block);
385 err = jread(&bh, journal, next_log_block);
386 if (err)
387 goto failed;
389 next_log_block++;
390 wrap(journal, next_log_block);
392 /* What kind of buffer is it?
394 * If it is a descriptor block, check that it has the
395 * expected sequence number. Otherwise, we're all done
396 * here. */
398 tmp = (journal_header_t *)bh->b_data;
400 if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
401 brelse(bh);
402 break;
405 blocktype = be32_to_cpu(tmp->h_blocktype);
406 sequence = be32_to_cpu(tmp->h_sequence);
407 jbd_debug(3, "Found magic %d, sequence %d\n",
408 blocktype, sequence);
410 if (sequence != next_commit_ID) {
411 brelse(bh);
412 break;
415 /* OK, we have a valid descriptor block which matches
416 * all of the sequence number checks. What are we going
417 * to do with it? That depends on the pass... */
419 switch(blocktype) {
420 case JBD2_DESCRIPTOR_BLOCK:
421 /* If it is a valid descriptor block, replay it
422 * in pass REPLAY; otherwise, just skip over the
423 * blocks it describes. */
424 if (pass != PASS_REPLAY) {
425 next_log_block += count_tags(journal, bh);
426 wrap(journal, next_log_block);
427 brelse(bh);
428 continue;
431 /* A descriptor block: we can now write all of
432 * the data blocks. Yay, useful work is finally
433 * getting done here! */
435 tagp = &bh->b_data[sizeof(journal_header_t)];
436 while ((tagp - bh->b_data + tag_bytes)
437 <= journal->j_blocksize) {
438 unsigned long io_block;
440 tag = (journal_block_tag_t *) tagp;
441 flags = be32_to_cpu(tag->t_flags);
443 io_block = next_log_block++;
444 wrap(journal, next_log_block);
445 err = jread(&obh, journal, io_block);
446 if (err) {
447 /* Recover what we can, but
448 * report failure at the end. */
449 success = err;
450 printk (KERN_ERR
451 "JBD: IO error %d recovering "
452 "block %ld in log\n",
453 err, io_block);
454 } else {
455 unsigned long long blocknr;
457 J_ASSERT(obh != NULL);
458 blocknr = read_tag_block(tag_bytes,
459 tag);
461 /* If the block has been
462 * revoked, then we're all done
463 * here. */
464 if (jbd2_journal_test_revoke
465 (journal, blocknr,
466 next_commit_ID)) {
467 brelse(obh);
468 ++info->nr_revoke_hits;
469 goto skip_write;
472 /* Find a buffer for the new
473 * data being restored */
474 nbh = __getblk(journal->j_fs_dev,
475 blocknr,
476 journal->j_blocksize);
477 if (nbh == NULL) {
478 printk(KERN_ERR
479 "JBD: Out of memory "
480 "during recovery.\n");
481 err = -ENOMEM;
482 brelse(bh);
483 brelse(obh);
484 goto failed;
487 lock_buffer(nbh);
488 memcpy(nbh->b_data, obh->b_data,
489 journal->j_blocksize);
490 if (flags & JBD2_FLAG_ESCAPE) {
491 *((__be32 *)bh->b_data) =
492 cpu_to_be32(JBD2_MAGIC_NUMBER);
495 BUFFER_TRACE(nbh, "marking dirty");
496 set_buffer_uptodate(nbh);
497 mark_buffer_dirty(nbh);
498 BUFFER_TRACE(nbh, "marking uptodate");
499 ++info->nr_replays;
500 /* ll_rw_block(WRITE, 1, &nbh); */
501 unlock_buffer(nbh);
502 brelse(obh);
503 brelse(nbh);
506 skip_write:
507 tagp += tag_bytes;
508 if (!(flags & JBD2_FLAG_SAME_UUID))
509 tagp += 16;
511 if (flags & JBD2_FLAG_LAST_TAG)
512 break;
515 brelse(bh);
516 continue;
518 case JBD2_COMMIT_BLOCK:
519 /* Found an expected commit block: not much to
520 * do other than move on to the next sequence
521 * number. */
522 brelse(bh);
523 next_commit_ID++;
524 continue;
526 case JBD2_REVOKE_BLOCK:
527 /* If we aren't in the REVOKE pass, then we can
528 * just skip over this block. */
529 if (pass != PASS_REVOKE) {
530 brelse(bh);
531 continue;
534 err = scan_revoke_records(journal, bh,
535 next_commit_ID, info);
536 brelse(bh);
537 if (err)
538 goto failed;
539 continue;
541 default:
542 jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
543 blocktype);
544 brelse(bh);
545 goto done;
549 done:
551 * We broke out of the log scan loop: either we came to the
552 * known end of the log or we found an unexpected block in the
553 * log. If the latter happened, then we know that the "current"
554 * transaction marks the end of the valid log.
557 if (pass == PASS_SCAN)
558 info->end_transaction = next_commit_ID;
559 else {
560 /* It's really bad news if different passes end up at
561 * different places (but possible due to IO errors). */
562 if (info->end_transaction != next_commit_ID) {
563 printk (KERN_ERR "JBD: recovery pass %d ended at "
564 "transaction %u, expected %u\n",
565 pass, next_commit_ID, info->end_transaction);
566 if (!success)
567 success = -EIO;
571 return success;
573 failed:
574 return err;
578 /* Scan a revoke record, marking all blocks mentioned as revoked. */
580 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
581 tid_t sequence, struct recovery_info *info)
583 jbd2_journal_revoke_header_t *header;
584 int offset, max;
585 int record_len = 4;
587 header = (jbd2_journal_revoke_header_t *) bh->b_data;
588 offset = sizeof(jbd2_journal_revoke_header_t);
589 max = be32_to_cpu(header->r_count);
591 if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
592 record_len = 8;
594 while (offset + record_len <= max) {
595 unsigned long long blocknr;
596 int err;
598 if (record_len == 4)
599 blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
600 else
601 blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
602 offset += record_len;
603 err = jbd2_journal_set_revoke(journal, blocknr, sequence);
604 if (err)
605 return err;
606 ++info->nr_revokes;
608 return 0;