xref: /openbmc/linux/fs/jbd2/recovery.c (revision f97769fd)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * linux/fs/jbd2/recovery.c
4  *
5  * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
6  *
7  * Copyright 1999-2000 Red Hat Software --- All Rights Reserved
8  *
9  * Journal recovery routines for the generic filesystem journaling code;
10  * part of the ext2fs journaling system.
11  */
12 
13 #ifndef __KERNEL__
14 #include "jfs_user.h"
15 #else
16 #include <linux/time.h>
17 #include <linux/fs.h>
18 #include <linux/jbd2.h>
19 #include <linux/errno.h>
20 #include <linux/crc32.h>
21 #include <linux/blkdev.h>
22 #endif
23 
24 /*
25  * Maintain information about the progress of the recovery job, so that
26  * the different passes can carry information between them.
27  */
28 struct recovery_info
29 {
30 	tid_t		start_transaction;
31 	tid_t		end_transaction;
32 
33 	int		nr_replays;
34 	int		nr_revokes;
35 	int		nr_revoke_hits;
36 };
37 
38 enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY};
39 static int do_one_pass(journal_t *journal,
40 				struct recovery_info *info, enum passtype pass);
41 static int scan_revoke_records(journal_t *, struct buffer_head *,
42 				tid_t, struct recovery_info *);
43 
44 #ifdef __KERNEL__
45 
46 /* Release readahead buffers after use */
47 static void journal_brelse_array(struct buffer_head *b[], int n)
48 {
49 	while (--n >= 0)
50 		brelse (b[n]);
51 }
52 
53 
54 /*
55  * When reading from the journal, we are going through the block device
56  * layer directly and so there is no readahead being done for us.  We
57  * need to implement any readahead ourselves if we want it to happen at
58  * all.  Recovery is basically one long sequential read, so make sure we
59  * do the IO in reasonably large chunks.
60  *
61  * This is not so critical that we need to be enormously clever about
62  * the readahead size, though.  128K is a purely arbitrary, good-enough
63  * fixed value.
64  */
65 
66 #define MAXBUF 8
67 static int do_readahead(journal_t *journal, unsigned int start)
68 {
69 	int err;
70 	unsigned int max, nbufs, next;
71 	unsigned long long blocknr;
72 	struct buffer_head *bh;
73 
74 	struct buffer_head * bufs[MAXBUF];
75 
76 	/* Do up to 128K of readahead */
77 	max = start + (128 * 1024 / journal->j_blocksize);
78 	if (max > journal->j_maxlen)
79 		max = journal->j_maxlen;
80 
81 	/* Do the readahead itself.  We'll submit MAXBUF buffer_heads at
82 	 * a time to the block device IO layer. */
83 
84 	nbufs = 0;
85 
86 	for (next = start; next < max; next++) {
87 		err = jbd2_journal_bmap(journal, next, &blocknr);
88 
89 		if (err) {
90 			printk(KERN_ERR "JBD2: bad block at offset %u\n",
91 				next);
92 			goto failed;
93 		}
94 
95 		bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
96 		if (!bh) {
97 			err = -ENOMEM;
98 			goto failed;
99 		}
100 
101 		if (!buffer_uptodate(bh) && !buffer_locked(bh)) {
102 			bufs[nbufs++] = bh;
103 			if (nbufs == MAXBUF) {
104 				ll_rw_block(REQ_OP_READ, 0, nbufs, bufs);
105 				journal_brelse_array(bufs, nbufs);
106 				nbufs = 0;
107 			}
108 		} else
109 			brelse(bh);
110 	}
111 
112 	if (nbufs)
113 		ll_rw_block(REQ_OP_READ, 0, nbufs, bufs);
114 	err = 0;
115 
116 failed:
117 	if (nbufs)
118 		journal_brelse_array(bufs, nbufs);
119 	return err;
120 }
121 
122 #endif /* __KERNEL__ */
123 
124 
125 /*
126  * Read a block from the journal
127  */
128 
129 static int jread(struct buffer_head **bhp, journal_t *journal,
130 		 unsigned int offset)
131 {
132 	int err;
133 	unsigned long long blocknr;
134 	struct buffer_head *bh;
135 
136 	*bhp = NULL;
137 
138 	if (offset >= journal->j_maxlen) {
139 		printk(KERN_ERR "JBD2: corrupted journal superblock\n");
140 		return -EFSCORRUPTED;
141 	}
142 
143 	err = jbd2_journal_bmap(journal, offset, &blocknr);
144 
145 	if (err) {
146 		printk(KERN_ERR "JBD2: bad block at offset %u\n",
147 			offset);
148 		return err;
149 	}
150 
151 	bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
152 	if (!bh)
153 		return -ENOMEM;
154 
155 	if (!buffer_uptodate(bh)) {
156 		/* If this is a brand new buffer, start readahead.
157                    Otherwise, we assume we are already reading it.  */
158 		if (!buffer_req(bh))
159 			do_readahead(journal, offset);
160 		wait_on_buffer(bh);
161 	}
162 
163 	if (!buffer_uptodate(bh)) {
164 		printk(KERN_ERR "JBD2: Failed to read block at offset %u\n",
165 			offset);
166 		brelse(bh);
167 		return -EIO;
168 	}
169 
170 	*bhp = bh;
171 	return 0;
172 }
173 
174 static int jbd2_descriptor_block_csum_verify(journal_t *j, void *buf)
175 {
176 	struct jbd2_journal_block_tail *tail;
177 	__be32 provided;
178 	__u32 calculated;
179 
180 	if (!jbd2_journal_has_csum_v2or3(j))
181 		return 1;
182 
183 	tail = (struct jbd2_journal_block_tail *)(buf + j->j_blocksize -
184 			sizeof(struct jbd2_journal_block_tail));
185 	provided = tail->t_checksum;
186 	tail->t_checksum = 0;
187 	calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
188 	tail->t_checksum = provided;
189 
190 	return provided == cpu_to_be32(calculated);
191 }
192 
193 /*
194  * Count the number of in-use tags in a journal descriptor block.
195  */
196 
197 static int count_tags(journal_t *journal, struct buffer_head *bh)
198 {
199 	char *			tagp;
200 	journal_block_tag_t *	tag;
201 	int			nr = 0, size = journal->j_blocksize;
202 	int			tag_bytes = journal_tag_bytes(journal);
203 
204 	if (jbd2_journal_has_csum_v2or3(journal))
205 		size -= sizeof(struct jbd2_journal_block_tail);
206 
207 	tagp = &bh->b_data[sizeof(journal_header_t)];
208 
209 	while ((tagp - bh->b_data + tag_bytes) <= size) {
210 		tag = (journal_block_tag_t *) tagp;
211 
212 		nr++;
213 		tagp += tag_bytes;
214 		if (!(tag->t_flags & cpu_to_be16(JBD2_FLAG_SAME_UUID)))
215 			tagp += 16;
216 
217 		if (tag->t_flags & cpu_to_be16(JBD2_FLAG_LAST_TAG))
218 			break;
219 	}
220 
221 	return nr;
222 }
223 
224 
225 /* Make sure we wrap around the log correctly! */
226 #define wrap(journal, var)						\
227 do {									\
228 	if (var >= (journal)->j_last)					\
229 		var -= ((journal)->j_last - (journal)->j_first);	\
230 } while (0)
231 
232 /**
233  * jbd2_journal_recover - recovers a on-disk journal
234  * @journal: the journal to recover
235  *
236  * The primary function for recovering the log contents when mounting a
237  * journaled device.
238  *
239  * Recovery is done in three passes.  In the first pass, we look for the
240  * end of the log.  In the second, we assemble the list of revoke
241  * blocks.  In the third and final pass, we replay any un-revoked blocks
242  * in the log.
243  */
244 int jbd2_journal_recover(journal_t *journal)
245 {
246 	int			err, err2;
247 	journal_superblock_t *	sb;
248 
249 	struct recovery_info	info;
250 
251 	memset(&info, 0, sizeof(info));
252 	sb = journal->j_superblock;
253 
254 	/*
255 	 * The journal superblock's s_start field (the current log head)
256 	 * is always zero if, and only if, the journal was cleanly
257 	 * unmounted.
258 	 */
259 
260 	if (!sb->s_start) {
261 		jbd_debug(1, "No recovery required, last transaction %d\n",
262 			  be32_to_cpu(sb->s_sequence));
263 		journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
264 		return 0;
265 	}
266 
267 	err = do_one_pass(journal, &info, PASS_SCAN);
268 	if (!err)
269 		err = do_one_pass(journal, &info, PASS_REVOKE);
270 	if (!err)
271 		err = do_one_pass(journal, &info, PASS_REPLAY);
272 
273 	jbd_debug(1, "JBD2: recovery, exit status %d, "
274 		  "recovered transactions %u to %u\n",
275 		  err, info.start_transaction, info.end_transaction);
276 	jbd_debug(1, "JBD2: Replayed %d and revoked %d/%d blocks\n",
277 		  info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
278 
279 	/* Restart the log at the next transaction ID, thus invalidating
280 	 * any existing commit records in the log. */
281 	journal->j_transaction_sequence = ++info.end_transaction;
282 
283 	jbd2_journal_clear_revoke(journal);
284 	err2 = sync_blockdev(journal->j_fs_dev);
285 	if (!err)
286 		err = err2;
287 	/* Make sure all replayed data is on permanent storage */
288 	if (journal->j_flags & JBD2_BARRIER) {
289 		err2 = blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL);
290 		if (!err)
291 			err = err2;
292 	}
293 	return err;
294 }
295 
296 /**
297  * jbd2_journal_skip_recovery - Start journal and wipe exiting records
298  * @journal: journal to startup
299  *
300  * Locate any valid recovery information from the journal and set up the
301  * journal structures in memory to ignore it (presumably because the
302  * caller has evidence that it is out of date).
303  * This function doesn't appear to be exported..
304  *
305  * We perform one pass over the journal to allow us to tell the user how
306  * much recovery information is being erased, and to let us initialise
307  * the journal transaction sequence numbers to the next unused ID.
308  */
309 int jbd2_journal_skip_recovery(journal_t *journal)
310 {
311 	int			err;
312 
313 	struct recovery_info	info;
314 
315 	memset (&info, 0, sizeof(info));
316 
317 	err = do_one_pass(journal, &info, PASS_SCAN);
318 
319 	if (err) {
320 		printk(KERN_ERR "JBD2: error %d scanning journal\n", err);
321 		++journal->j_transaction_sequence;
322 	} else {
323 #ifdef CONFIG_JBD2_DEBUG
324 		int dropped = info.end_transaction -
325 			be32_to_cpu(journal->j_superblock->s_sequence);
326 		jbd_debug(1,
327 			  "JBD2: ignoring %d transaction%s from the journal.\n",
328 			  dropped, (dropped == 1) ? "" : "s");
329 #endif
330 		journal->j_transaction_sequence = ++info.end_transaction;
331 	}
332 
333 	journal->j_tail = 0;
334 	return err;
335 }
336 
337 static inline unsigned long long read_tag_block(journal_t *journal,
338 						journal_block_tag_t *tag)
339 {
340 	unsigned long long block = be32_to_cpu(tag->t_blocknr);
341 	if (jbd2_has_feature_64bit(journal))
342 		block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
343 	return block;
344 }
345 
346 /*
347  * calc_chksums calculates the checksums for the blocks described in the
348  * descriptor block.
349  */
350 static int calc_chksums(journal_t *journal, struct buffer_head *bh,
351 			unsigned long *next_log_block, __u32 *crc32_sum)
352 {
353 	int i, num_blks, err;
354 	unsigned long io_block;
355 	struct buffer_head *obh;
356 
357 	num_blks = count_tags(journal, bh);
358 	/* Calculate checksum of the descriptor block. */
359 	*crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
360 
361 	for (i = 0; i < num_blks; i++) {
362 		io_block = (*next_log_block)++;
363 		wrap(journal, *next_log_block);
364 		err = jread(&obh, journal, io_block);
365 		if (err) {
366 			printk(KERN_ERR "JBD2: IO error %d recovering block "
367 				"%lu in log\n", err, io_block);
368 			return 1;
369 		} else {
370 			*crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
371 				     obh->b_size);
372 		}
373 		put_bh(obh);
374 	}
375 	return 0;
376 }
377 
378 static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
379 {
380 	struct commit_header *h;
381 	__be32 provided;
382 	__u32 calculated;
383 
384 	if (!jbd2_journal_has_csum_v2or3(j))
385 		return 1;
386 
387 	h = buf;
388 	provided = h->h_chksum[0];
389 	h->h_chksum[0] = 0;
390 	calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
391 	h->h_chksum[0] = provided;
392 
393 	return provided == cpu_to_be32(calculated);
394 }
395 
396 static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
397 				      void *buf, __u32 sequence)
398 {
399 	journal_block_tag3_t *tag3 = (journal_block_tag3_t *)tag;
400 	__u32 csum32;
401 	__be32 seq;
402 
403 	if (!jbd2_journal_has_csum_v2or3(j))
404 		return 1;
405 
406 	seq = cpu_to_be32(sequence);
407 	csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
408 	csum32 = jbd2_chksum(j, csum32, buf, j->j_blocksize);
409 
410 	if (jbd2_has_feature_csum3(j))
411 		return tag3->t_checksum == cpu_to_be32(csum32);
412 	else
413 		return tag->t_checksum == cpu_to_be16(csum32);
414 }
415 
416 static int do_one_pass(journal_t *journal,
417 			struct recovery_info *info, enum passtype pass)
418 {
419 	unsigned int		first_commit_ID, next_commit_ID;
420 	unsigned long		next_log_block;
421 	int			err, success = 0;
422 	journal_superblock_t *	sb;
423 	journal_header_t *	tmp;
424 	struct buffer_head *	bh;
425 	unsigned int		sequence;
426 	int			blocktype;
427 	int			tag_bytes = journal_tag_bytes(journal);
428 	__u32			crc32_sum = ~0; /* Transactional Checksums */
429 	int			descr_csum_size = 0;
430 	int			block_error = 0;
431 
432 	/*
433 	 * First thing is to establish what we expect to find in the log
434 	 * (in terms of transaction IDs), and where (in terms of log
435 	 * block offsets): query the superblock.
436 	 */
437 
438 	sb = journal->j_superblock;
439 	next_commit_ID = be32_to_cpu(sb->s_sequence);
440 	next_log_block = be32_to_cpu(sb->s_start);
441 
442 	first_commit_ID = next_commit_ID;
443 	if (pass == PASS_SCAN)
444 		info->start_transaction = first_commit_ID;
445 
446 	jbd_debug(1, "Starting recovery pass %d\n", pass);
447 
448 	/*
449 	 * Now we walk through the log, transaction by transaction,
450 	 * making sure that each transaction has a commit block in the
451 	 * expected place.  Each complete transaction gets replayed back
452 	 * into the main filesystem.
453 	 */
454 
455 	while (1) {
456 		int			flags;
457 		char *			tagp;
458 		journal_block_tag_t *	tag;
459 		struct buffer_head *	obh;
460 		struct buffer_head *	nbh;
461 
462 		cond_resched();
463 
464 		/* If we already know where to stop the log traversal,
465 		 * check right now that we haven't gone past the end of
466 		 * the log. */
467 
468 		if (pass != PASS_SCAN)
469 			if (tid_geq(next_commit_ID, info->end_transaction))
470 				break;
471 
472 		jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
473 			  next_commit_ID, next_log_block, journal->j_last);
474 
475 		/* Skip over each chunk of the transaction looking
476 		 * either the next descriptor block or the final commit
477 		 * record. */
478 
479 		jbd_debug(3, "JBD2: checking block %ld\n", next_log_block);
480 		err = jread(&bh, journal, next_log_block);
481 		if (err)
482 			goto failed;
483 
484 		next_log_block++;
485 		wrap(journal, next_log_block);
486 
487 		/* What kind of buffer is it?
488 		 *
489 		 * If it is a descriptor block, check that it has the
490 		 * expected sequence number.  Otherwise, we're all done
491 		 * here. */
492 
493 		tmp = (journal_header_t *)bh->b_data;
494 
495 		if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
496 			brelse(bh);
497 			break;
498 		}
499 
500 		blocktype = be32_to_cpu(tmp->h_blocktype);
501 		sequence = be32_to_cpu(tmp->h_sequence);
502 		jbd_debug(3, "Found magic %d, sequence %d\n",
503 			  blocktype, sequence);
504 
505 		if (sequence != next_commit_ID) {
506 			brelse(bh);
507 			break;
508 		}
509 
510 		/* OK, we have a valid descriptor block which matches
511 		 * all of the sequence number checks.  What are we going
512 		 * to do with it?  That depends on the pass... */
513 
514 		switch(blocktype) {
515 		case JBD2_DESCRIPTOR_BLOCK:
516 			/* Verify checksum first */
517 			if (jbd2_journal_has_csum_v2or3(journal))
518 				descr_csum_size =
519 					sizeof(struct jbd2_journal_block_tail);
520 			if (descr_csum_size > 0 &&
521 			    !jbd2_descriptor_block_csum_verify(journal,
522 							       bh->b_data)) {
523 				printk(KERN_ERR "JBD2: Invalid checksum "
524 				       "recovering block %lu in log\n",
525 				       next_log_block);
526 				err = -EFSBADCRC;
527 				brelse(bh);
528 				goto failed;
529 			}
530 
531 			/* If it is a valid descriptor block, replay it
532 			 * in pass REPLAY; if journal_checksums enabled, then
533 			 * calculate checksums in PASS_SCAN, otherwise,
534 			 * just skip over the blocks it describes. */
535 			if (pass != PASS_REPLAY) {
536 				if (pass == PASS_SCAN &&
537 				    jbd2_has_feature_checksum(journal) &&
538 				    !info->end_transaction) {
539 					if (calc_chksums(journal, bh,
540 							&next_log_block,
541 							&crc32_sum)) {
542 						put_bh(bh);
543 						break;
544 					}
545 					put_bh(bh);
546 					continue;
547 				}
548 				next_log_block += count_tags(journal, bh);
549 				wrap(journal, next_log_block);
550 				put_bh(bh);
551 				continue;
552 			}
553 
554 			/* A descriptor block: we can now write all of
555 			 * the data blocks.  Yay, useful work is finally
556 			 * getting done here! */
557 
558 			tagp = &bh->b_data[sizeof(journal_header_t)];
559 			while ((tagp - bh->b_data + tag_bytes)
560 			       <= journal->j_blocksize - descr_csum_size) {
561 				unsigned long io_block;
562 
563 				tag = (journal_block_tag_t *) tagp;
564 				flags = be16_to_cpu(tag->t_flags);
565 
566 				io_block = next_log_block++;
567 				wrap(journal, next_log_block);
568 				err = jread(&obh, journal, io_block);
569 				if (err) {
570 					/* Recover what we can, but
571 					 * report failure at the end. */
572 					success = err;
573 					printk(KERN_ERR
574 						"JBD2: IO error %d recovering "
575 						"block %ld in log\n",
576 						err, io_block);
577 				} else {
578 					unsigned long long blocknr;
579 
580 					J_ASSERT(obh != NULL);
581 					blocknr = read_tag_block(journal,
582 								 tag);
583 
584 					/* If the block has been
585 					 * revoked, then we're all done
586 					 * here. */
587 					if (jbd2_journal_test_revoke
588 					    (journal, blocknr,
589 					     next_commit_ID)) {
590 						brelse(obh);
591 						++info->nr_revoke_hits;
592 						goto skip_write;
593 					}
594 
595 					/* Look for block corruption */
596 					if (!jbd2_block_tag_csum_verify(
597 						journal, tag, obh->b_data,
598 						be32_to_cpu(tmp->h_sequence))) {
599 						brelse(obh);
600 						success = -EFSBADCRC;
601 						printk(KERN_ERR "JBD2: Invalid "
602 						       "checksum recovering "
603 						       "data block %llu in "
604 						       "log\n", blocknr);
605 						block_error = 1;
606 						goto skip_write;
607 					}
608 
609 					/* Find a buffer for the new
610 					 * data being restored */
611 					nbh = __getblk(journal->j_fs_dev,
612 							blocknr,
613 							journal->j_blocksize);
614 					if (nbh == NULL) {
615 						printk(KERN_ERR
616 						       "JBD2: Out of memory "
617 						       "during recovery.\n");
618 						err = -ENOMEM;
619 						brelse(bh);
620 						brelse(obh);
621 						goto failed;
622 					}
623 
624 					lock_buffer(nbh);
625 					memcpy(nbh->b_data, obh->b_data,
626 							journal->j_blocksize);
627 					if (flags & JBD2_FLAG_ESCAPE) {
628 						*((__be32 *)nbh->b_data) =
629 						cpu_to_be32(JBD2_MAGIC_NUMBER);
630 					}
631 
632 					BUFFER_TRACE(nbh, "marking dirty");
633 					set_buffer_uptodate(nbh);
634 					mark_buffer_dirty(nbh);
635 					BUFFER_TRACE(nbh, "marking uptodate");
636 					++info->nr_replays;
637 					/* ll_rw_block(WRITE, 1, &nbh); */
638 					unlock_buffer(nbh);
639 					brelse(obh);
640 					brelse(nbh);
641 				}
642 
643 			skip_write:
644 				tagp += tag_bytes;
645 				if (!(flags & JBD2_FLAG_SAME_UUID))
646 					tagp += 16;
647 
648 				if (flags & JBD2_FLAG_LAST_TAG)
649 					break;
650 			}
651 
652 			brelse(bh);
653 			continue;
654 
655 		case JBD2_COMMIT_BLOCK:
656 			/*     How to differentiate between interrupted commit
657 			 *               and journal corruption ?
658 			 *
659 			 * {nth transaction}
660 			 *        Checksum Verification Failed
661 			 *			 |
662 			 *		 ____________________
663 			 *		|		     |
664 			 * 	async_commit             sync_commit
665 			 *     		|                    |
666 			 *		| GO TO NEXT    "Journal Corruption"
667 			 *		| TRANSACTION
668 			 *		|
669 			 * {(n+1)th transanction}
670 			 *		|
671 			 * 	 _______|______________
672 			 * 	|	 	      |
673 			 * Commit block found	Commit block not found
674 			 *      |		      |
675 			 * "Journal Corruption"       |
676 			 *		 _____________|_________
677 			 *     		|	           	|
678 			 *	nth trans corrupt	OR   nth trans
679 			 *	and (n+1)th interrupted     interrupted
680 			 *	before commit block
681 			 *      could reach the disk.
682 			 *	(Cannot find the difference in above
683 			 *	 mentioned conditions. Hence assume
684 			 *	 "Interrupted Commit".)
685 			 */
686 
687 			/* Found an expected commit block: if checksums
688 			 * are present verify them in PASS_SCAN; else not
689 			 * much to do other than move on to the next sequence
690 			 * number. */
691 			if (pass == PASS_SCAN &&
692 			    jbd2_has_feature_checksum(journal)) {
693 				struct commit_header *cbh =
694 					(struct commit_header *)bh->b_data;
695 				unsigned found_chksum =
696 					be32_to_cpu(cbh->h_chksum[0]);
697 
698 				if (info->end_transaction) {
699 					journal->j_failed_commit =
700 						info->end_transaction;
701 					brelse(bh);
702 					break;
703 				}
704 
705 				/* Neither checksum match nor unused? */
706 				if (!((crc32_sum == found_chksum &&
707 				       cbh->h_chksum_type ==
708 						JBD2_CRC32_CHKSUM &&
709 				       cbh->h_chksum_size ==
710 						JBD2_CRC32_CHKSUM_SIZE) ||
711 				      (cbh->h_chksum_type == 0 &&
712 				       cbh->h_chksum_size == 0 &&
713 				       found_chksum == 0)))
714 					goto chksum_error;
715 
716 				crc32_sum = ~0;
717 			}
718 			if (pass == PASS_SCAN &&
719 			    !jbd2_commit_block_csum_verify(journal,
720 							   bh->b_data)) {
721 			chksum_error:
722 				info->end_transaction = next_commit_ID;
723 
724 				if (!jbd2_has_feature_async_commit(journal)) {
725 					journal->j_failed_commit =
726 						next_commit_ID;
727 					brelse(bh);
728 					break;
729 				}
730 			}
731 			brelse(bh);
732 			next_commit_ID++;
733 			continue;
734 
735 		case JBD2_REVOKE_BLOCK:
736 			/* If we aren't in the REVOKE pass, then we can
737 			 * just skip over this block. */
738 			if (pass != PASS_REVOKE) {
739 				brelse(bh);
740 				continue;
741 			}
742 
743 			err = scan_revoke_records(journal, bh,
744 						  next_commit_ID, info);
745 			brelse(bh);
746 			if (err)
747 				goto failed;
748 			continue;
749 
750 		default:
751 			jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
752 				  blocktype);
753 			brelse(bh);
754 			goto done;
755 		}
756 	}
757 
758  done:
759 	/*
760 	 * We broke out of the log scan loop: either we came to the
761 	 * known end of the log or we found an unexpected block in the
762 	 * log.  If the latter happened, then we know that the "current"
763 	 * transaction marks the end of the valid log.
764 	 */
765 
766 	if (pass == PASS_SCAN) {
767 		if (!info->end_transaction)
768 			info->end_transaction = next_commit_ID;
769 	} else {
770 		/* It's really bad news if different passes end up at
771 		 * different places (but possible due to IO errors). */
772 		if (info->end_transaction != next_commit_ID) {
773 			printk(KERN_ERR "JBD2: recovery pass %d ended at "
774 				"transaction %u, expected %u\n",
775 				pass, next_commit_ID, info->end_transaction);
776 			if (!success)
777 				success = -EIO;
778 		}
779 	}
780 	if (block_error && success == 0)
781 		success = -EIO;
782 	return success;
783 
784  failed:
785 	return err;
786 }
787 
788 /* Scan a revoke record, marking all blocks mentioned as revoked. */
789 
790 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
791 			       tid_t sequence, struct recovery_info *info)
792 {
793 	jbd2_journal_revoke_header_t *header;
794 	int offset, max;
795 	int csum_size = 0;
796 	__u32 rcount;
797 	int record_len = 4;
798 
799 	header = (jbd2_journal_revoke_header_t *) bh->b_data;
800 	offset = sizeof(jbd2_journal_revoke_header_t);
801 	rcount = be32_to_cpu(header->r_count);
802 
803 	if (!jbd2_descriptor_block_csum_verify(journal, header))
804 		return -EFSBADCRC;
805 
806 	if (jbd2_journal_has_csum_v2or3(journal))
807 		csum_size = sizeof(struct jbd2_journal_block_tail);
808 	if (rcount > journal->j_blocksize - csum_size)
809 		return -EINVAL;
810 	max = rcount;
811 
812 	if (jbd2_has_feature_64bit(journal))
813 		record_len = 8;
814 
815 	while (offset + record_len <= max) {
816 		unsigned long long blocknr;
817 		int err;
818 
819 		if (record_len == 4)
820 			blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
821 		else
822 			blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
823 		offset += record_len;
824 		err = jbd2_journal_set_revoke(journal, blocknr, sequence);
825 		if (err)
826 			return err;
827 		++info->nr_revokes;
828 	}
829 	return 0;
830 }
831