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Linux/fs/jbd2/recovery.c

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  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, NULL);
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                                 int chksum_err, chksum_seen;
694                                 struct commit_header *cbh =
695                                         (struct commit_header *)bh->b_data;
696                                 unsigned found_chksum =
697                                         be32_to_cpu(cbh->h_chksum[0]);
698 
699                                 chksum_err = chksum_seen = 0;
700 
701                                 if (info->end_transaction) {
702                                         journal->j_failed_commit =
703                                                 info->end_transaction;
704                                         brelse(bh);
705                                         break;
706                                 }
707 
708                                 if (crc32_sum == found_chksum &&
709                                     cbh->h_chksum_type == JBD2_CRC32_CHKSUM &&
710                                     cbh->h_chksum_size ==
711                                                 JBD2_CRC32_CHKSUM_SIZE)
712                                        chksum_seen = 1;
713                                 else if (!(cbh->h_chksum_type == 0 &&
714                                              cbh->h_chksum_size == 0 &&
715                                              found_chksum == 0 &&
716                                              !chksum_seen))
717                                 /*
718                                  * If fs is mounted using an old kernel and then
719                                  * kernel with journal_chksum is used then we
720                                  * get a situation where the journal flag has
721                                  * checksum flag set but checksums are not
722                                  * present i.e chksum = 0, in the individual
723                                  * commit blocks.
724                                  * Hence to avoid checksum failures, in this
725                                  * situation, this extra check is added.
726                                  */
727                                                 chksum_err = 1;
728 
729                                 if (chksum_err) {
730                                         info->end_transaction = next_commit_ID;
731 
732                                         if (!jbd2_has_feature_async_commit(journal)) {
733                                                 journal->j_failed_commit =
734                                                         next_commit_ID;
735                                                 brelse(bh);
736                                                 break;
737                                         }
738                                 }
739                                 crc32_sum = ~0;
740                         }
741                         if (pass == PASS_SCAN &&
742                             !jbd2_commit_block_csum_verify(journal,
743                                                            bh->b_data)) {
744                                 info->end_transaction = next_commit_ID;
745 
746                                 if (!jbd2_has_feature_async_commit(journal)) {
747                                         journal->j_failed_commit =
748                                                 next_commit_ID;
749                                         brelse(bh);
750                                         break;
751                                 }
752                         }
753                         brelse(bh);
754                         next_commit_ID++;
755                         continue;
756 
757                 case JBD2_REVOKE_BLOCK:
758                         /* If we aren't in the REVOKE pass, then we can
759                          * just skip over this block. */
760                         if (pass != PASS_REVOKE) {
761                                 brelse(bh);
762                                 continue;
763                         }
764 
765                         err = scan_revoke_records(journal, bh,
766                                                   next_commit_ID, info);
767                         brelse(bh);
768                         if (err)
769                                 goto failed;
770                         continue;
771 
772                 default:
773                         jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
774                                   blocktype);
775                         brelse(bh);
776                         goto done;
777                 }
778         }
779 
780  done:
781         /*
782          * We broke out of the log scan loop: either we came to the
783          * known end of the log or we found an unexpected block in the
784          * log.  If the latter happened, then we know that the "current"
785          * transaction marks the end of the valid log.
786          */
787 
788         if (pass == PASS_SCAN) {
789                 if (!info->end_transaction)
790                         info->end_transaction = next_commit_ID;
791         } else {
792                 /* It's really bad news if different passes end up at
793                  * different places (but possible due to IO errors). */
794                 if (info->end_transaction != next_commit_ID) {
795                         printk(KERN_ERR "JBD2: recovery pass %d ended at "
796                                 "transaction %u, expected %u\n",
797                                 pass, next_commit_ID, info->end_transaction);
798                         if (!success)
799                                 success = -EIO;
800                 }
801         }
802         if (block_error && success == 0)
803                 success = -EIO;
804         return success;
805 
806  failed:
807         return err;
808 }
809 
810 /* Scan a revoke record, marking all blocks mentioned as revoked. */
811 
812 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
813                                tid_t sequence, struct recovery_info *info)
814 {
815         jbd2_journal_revoke_header_t *header;
816         int offset, max;
817         int csum_size = 0;
818         __u32 rcount;
819         int record_len = 4;
820 
821         header = (jbd2_journal_revoke_header_t *) bh->b_data;
822         offset = sizeof(jbd2_journal_revoke_header_t);
823         rcount = be32_to_cpu(header->r_count);
824 
825         if (!jbd2_descriptor_block_csum_verify(journal, header))
826                 return -EFSBADCRC;
827 
828         if (jbd2_journal_has_csum_v2or3(journal))
829                 csum_size = sizeof(struct jbd2_journal_block_tail);
830         if (rcount > journal->j_blocksize - csum_size)
831                 return -EINVAL;
832         max = rcount;
833 
834         if (jbd2_has_feature_64bit(journal))
835                 record_len = 8;
836 
837         while (offset + record_len <= max) {
838                 unsigned long long blocknr;
839                 int err;
840 
841                 if (record_len == 4)
842                         blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
843                 else
844                         blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
845                 offset += record_len;
846                 err = jbd2_journal_set_revoke(journal, blocknr, sequence);
847                 if (err)
848                         return err;
849                 ++info->nr_revokes;
850         }
851         return 0;
852 }
853 

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