fs/jbd2/recovery.c

   1 /*
   2  * linux/fs/jbd2/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/jbd2.h>
  22 #include <linux/errno.h>
  23 #include <linux/crc32.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
  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         while (--n >= 0)
  52                 brelse (b[n]);
  53 }
  54
  55
  56 /*
  57  * When reading from the journal, we are going through the block device
  58  * layer directly and so there is no readahead being done for us.  We
  59  * need to implement any readahead ourselves if we want it to happen at
  60  * all.  Recovery is basically one long sequential read, so make sure we
  61  * do the IO in reasonably large chunks.
  62  *
  63  * This is not so critical that we need to be enormously clever about
  64  * the readahead size, though.  128K is a purely arbitrary, good-enough
  65  * fixed value.
  66  */
  67
  68 #define MAXBUF 8
  69 static int do_readahead(journal_t *journal, unsigned int start)
  70 {
  71         int err;
  72         unsigned int max, nbufs, next;
  73         unsigned long long blocknr;
  74         struct buffer_head *bh;
  75
  76         struct buffer_head * bufs[MAXBUF];
  77
  78         /* Do up to 128K of readahead */
  79         max = start + (128 * 1024 / journal->j_blocksize);
  80         if (max > journal->j_maxlen)
  81                 max = journal->j_maxlen;
  82
  83         /* Do the readahead itself.  We'll submit MAXBUF buffer_heads at
  84          * a time to the block device IO layer. */
  85
  86         nbufs = 0;
  87
  88         for (next = start; next < max; next++) {
  89                 err = jbd2_journal_bmap(journal, next, &blocknr);
  90
  91                 if (err) {
  92                         printk (KERN_ERR "JBD: bad block at offset %u\n",
  93                                 next);
  94                         goto failed;
  95                 }
  96
  97                 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
  98                 if (!bh) {
  99                         err = -ENOMEM;
 100                         goto failed;
 101                 }
 102
 103                 if (!buffer_uptodate(bh) && !buffer_locked(bh)) {
 104                         bufs[nbufs++] = bh;
 105                         if (nbufs == MAXBUF) {
 106                                 ll_rw_block(READ, nbufs, bufs);
 107                                 journal_brelse_array(bufs, nbufs);
 108                                 nbufs = 0;
 109                         }
 110                 } else
 111                         brelse(bh);
 112         }
 113
 114         if (nbufs)
 115                 ll_rw_block(READ, nbufs, bufs);
 116         err = 0;
 117
 118 failed:
 119         if (nbufs)
 120                 journal_brelse_array(bufs, nbufs);
 121         return err;
 122 }
 123
 124 #endif /* __KERNEL__ */
 125
 126
 127 /*
 128  * Read a block from the journal
 129  */
 130
 131 static int jread(struct buffer_head **bhp, journal_t *journal,
 132                  unsigned int offset)
 133 {
 134         int err;
 135         unsigned long long blocknr;
 136         struct buffer_head *bh;
 137
 138         *bhp = NULL;
 139
 140         if (offset >= journal->j_maxlen) {
 141                 printk(KERN_ERR "JBD: corrupted journal superblock\n");
 142                 return -EIO;
 143         }
 144
 145         err = jbd2_journal_bmap(journal, offset, &blocknr);
 146
 147         if (err) {
 148                 printk (KERN_ERR "JBD: bad block at offset %u\n",
 149                         offset);
 150                 return err;
 151         }
 152
 153         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
 154         if (!bh)
 155                 return -ENOMEM;
 156
 157         if (!buffer_uptodate(bh)) {
 158                 /* If this is a brand new buffer, start readahead.
 159                    Otherwise, we assume we are already reading it.  */
 160                 if (!buffer_req(bh))
 161                         do_readahead(journal, offset);
 162                 wait_on_buffer(bh);
 163         }
 164
 165         if (!buffer_uptodate(bh)) {
 166                 printk (KERN_ERR "JBD: Failed to read block at offset %u\n",
 167                         offset);
 168                 brelse(bh);
 169                 return -EIO;
 170         }
 171
 172         *bhp = bh;
 173         return 0;
 174 }
 175
 176
 177 /*
 178  * Count the number of in-use tags in a journal descriptor block.
 179  */
 180
 181 static int count_tags(journal_t *journal, struct buffer_head *bh)
 182 {
 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);
 187
 188         tagp = &bh->b_data[sizeof(journal_header_t)];
 189
 190         while ((tagp - bh->b_data + tag_bytes) <= size) {
 191                 tag = (journal_block_tag_t *) tagp;
 192
 193                 nr++;
 194                 tagp += tag_bytes;
 195                 if (!(tag->t_flags & cpu_to_be32(JBD2_FLAG_SAME_UUID)))
 196                         tagp += 16;
 197
 198                 if (tag->t_flags & cpu_to_be32(JBD2_FLAG_LAST_TAG))
 199                         break;
 200         }
 201
 202         return nr;
 203 }
 204
 205
 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)
 212
 213 /**
 214  * jbd2_journal_recover - recovers a on-disk journal
 215  * @journal: the journal to recover
 216  *
 217  * The primary function for recovering the log contents when mounting a
 218  * journaled device.
 219  *
 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.
 224  */
 225 int jbd2_journal_recover(journal_t *journal)
 226 {
 227         int                     err, err2;
 228         journal_superblock_t *  sb;
 229
 230         struct recovery_info    info;
 231
 232         memset(&info, 0, sizeof(info));
 233         sb = journal->j_superblock;
 234
 235         /*
 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.
 239          */
 240
 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;
 246         }
 247
 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);
 253
 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);
 259
 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;
 263
 264         jbd2_journal_clear_revoke(journal);
 265         err2 = sync_blockdev(journal->j_fs_dev);
 266         if (!err)
 267                 err = err2;
 268
 269         return err;
 270 }
 271
 272 /**
 273  * jbd2_journal_skip_recovery - Start journal and wipe exiting records
 274  * @journal: journal to startup
 275  *
 276  * Locate any valid recovery information from the journal and set up the
 277  * journal structures in memory to ignore it (presumably because the
 278  * caller has evidence that it is out of date).
 279  * This function does'nt appear to be exorted..
 280  *
 281  * We perform one pass over the journal to allow us to tell the user how
 282  * much recovery information is being erased, and to let us initialise
 283  * the journal transaction sequence numbers to the next unused ID.
 284  */
 285 int jbd2_journal_skip_recovery(journal_t *journal)
 286 {
 287         int                     err;
 288         journal_superblock_t *  sb;
 289
 290         struct recovery_info    info;
 291
 292         memset (&info, 0, sizeof(info));
 293         sb = journal->j_superblock;
 294
 295         err = do_one_pass(journal, &info, PASS_SCAN);
 296
 297         if (err) {
 298                 printk(KERN_ERR "JBD: error %d scanning journal\n", err);
 299                 ++journal->j_transaction_sequence;
 300         } else {
 301 #ifdef CONFIG_JBD2_DEBUG
 302                 int dropped = info.end_transaction - be32_to_cpu(sb->s_sequence);
 303 #endif
 304                 jbd_debug(1,
 305                           "JBD: ignoring %d transaction%s from the journal.\n",
 306                           dropped, (dropped == 1) ? "" : "s");
 307                 journal->j_transaction_sequence = ++info.end_transaction;
 308         }
 309
 310         journal->j_tail = 0;
 311         return err;
 312 }
 313
 314 static inline unsigned long long read_tag_block(int tag_bytes, journal_block_tag_t *tag)
 315 {
 316         unsigned long long block = be32_to_cpu(tag->t_blocknr);
 317         if (tag_bytes > JBD2_TAG_SIZE32)
 318                 block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
 319         return block;
 320 }
 321
 322 /*
 323  * calc_chksums calculates the checksums for the blocks described in the
 324  * descriptor block.
 325  */
 326 static int calc_chksums(journal_t *journal, struct buffer_head *bh,
 327                         unsigned long *next_log_block, __u32 *crc32_sum)
 328 {
 329         int i, num_blks, err;
 330         unsigned long io_block;
 331         struct buffer_head *obh;
 332
 333         num_blks = count_tags(journal, bh);
 334         /* Calculate checksum of the descriptor block. */
 335         *crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
 336
 337         for (i = 0; i < num_blks; i++) {
 338                 io_block = (*next_log_block)++;
 339                 wrap(journal, *next_log_block);
 340                 err = jread(&obh, journal, io_block);
 341                 if (err) {
 342                         printk(KERN_ERR "JBD: IO error %d recovering block "
 343                                 "%lu in log\n", err, io_block);
 344                         return 1;
 345                 } else {
 346                         *crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
 347                                      obh->b_size);
 348                 }
 349                 put_bh(obh);
 350         }
 351         return 0;
 352 }
 353
 354 static int do_one_pass(journal_t *journal,
 355                         struct recovery_info *info, enum passtype pass)
 356 {
 357         unsigned int            first_commit_ID, next_commit_ID;
 358         unsigned long           next_log_block;
 359         int                     err, success = 0;
 360         journal_superblock_t *  sb;
 361         journal_header_t *      tmp;
 362         struct buffer_head *    bh;
 363         unsigned int            sequence;
 364         int                     blocktype;
 365         int                     tag_bytes = journal_tag_bytes(journal);
 366         __u32                   crc32_sum = ~0; /* Transactional Checksums */
 367
 368         /* Precompute the maximum metadata descriptors in a descriptor block */
 369         int                     MAX_BLOCKS_PER_DESC;
 370         MAX_BLOCKS_PER_DESC = ((journal->j_blocksize-sizeof(journal_header_t))
 371                                / tag_bytes);
 372
 373         /*
 374          * First thing is to establish what we expect to find in the log
 375          * (in terms of transaction IDs), and where (in terms of log
 376          * block offsets): query the superblock.
 377          */
 378
 379         sb = journal->j_superblock;
 380         next_commit_ID = be32_to_cpu(sb->s_sequence);
 381         next_log_block = be32_to_cpu(sb->s_start);
 382
 383         first_commit_ID = next_commit_ID;
 384         if (pass == PASS_SCAN)
 385                 info->start_transaction = first_commit_ID;
 386
 387         jbd_debug(1, "Starting recovery pass %d\n", pass);
 388
 389         /*
 390          * Now we walk through the log, transaction by transaction,
 391          * making sure that each transaction has a commit block in the
 392          * expected place.  Each complete transaction gets replayed back
 393          * into the main filesystem.
 394          */
 395
 396         while (1) {
 397                 int                     flags;
 398                 char *                  tagp;
 399                 journal_block_tag_t *   tag;
 400                 struct buffer_head *    obh;
 401                 struct buffer_head *    nbh;
 402
 403                 cond_resched();
 404
 405                 /* If we already know where to stop the log traversal,
 406                  * check right now that we haven't gone past the end of
 407                  * the log. */
 408
 409                 if (pass != PASS_SCAN)
 410                         if (tid_geq(next_commit_ID, info->end_transaction))
 411                                 break;
 412
 413                 jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
 414                           next_commit_ID, next_log_block, journal->j_last);
 415
 416                 /* Skip over each chunk of the transaction looking
 417                  * either the next descriptor block or the final commit
 418                  * record. */
 419
 420                 jbd_debug(3, "JBD: checking block %ld\n", next_log_block);
 421                 err = jread(&bh, journal, next_log_block);
 422                 if (err)
 423                         goto failed;
 424
 425                 next_log_block++;
 426                 wrap(journal, next_log_block);
 427
 428                 /* What kind of buffer is it?
 429                  *
 430                  * If it is a descriptor block, check that it has the
 431                  * expected sequence number.  Otherwise, we're all done
 432                  * here. */
 433
 434                 tmp = (journal_header_t *)bh->b_data;
 435
 436                 if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
 437                         brelse(bh);
 438                         break;
 439                 }
 440
 441                 blocktype = be32_to_cpu(tmp->h_blocktype);
 442                 sequence = be32_to_cpu(tmp->h_sequence);
 443                 jbd_debug(3, "Found magic %d, sequence %d\n",
 444                           blocktype, sequence);
 445
 446                 if (sequence != next_commit_ID) {
 447                         brelse(bh);
 448                         break;
 449                 }
 450
 451                 /* OK, we have a valid descriptor block which matches
 452                  * all of the sequence number checks.  What are we going
 453                  * to do with it?  That depends on the pass... */
 454
 455                 switch(blocktype) {
 456                 case JBD2_DESCRIPTOR_BLOCK:
 457                         /* If it is a valid descriptor block, replay it
 458                          * in pass REPLAY; if journal_checksums enabled, then
 459                          * calculate checksums in PASS_SCAN, otherwise,
 460                          * just skip over the blocks it describes. */
 461                         if (pass != PASS_REPLAY) {
 462                                 if (pass == PASS_SCAN &&
 463                                     JBD2_HAS_COMPAT_FEATURE(journal,
 464                                             JBD2_FEATURE_COMPAT_CHECKSUM) &&
 465                                     !info->end_transaction) {
 466                                         if (calc_chksums(journal, bh,
 467                                                         &next_log_block,
 468                                                         &crc32_sum)) {
 469                                                 put_bh(bh);
 470                                                 break;
 471                                         }
 472                                         put_bh(bh);
 473                                         continue;
 474                                 }
 475                                 next_log_block += count_tags(journal, bh);
 476                                 wrap(journal, next_log_block);
 477                                 put_bh(bh);
 478                                 continue;
 479                         }
 480
 481                         /* A descriptor block: we can now write all of
 482                          * the data blocks.  Yay, useful work is finally
 483                          * getting done here! */
 484
 485                         tagp = &bh->b_data[sizeof(journal_header_t)];
 486                         while ((tagp - bh->b_data + tag_bytes)
 487                                <= journal->j_blocksize) {
 488                                 unsigned long io_block;
 489
 490                                 tag = (journal_block_tag_t *) tagp;
 491                                 flags = be32_to_cpu(tag->t_flags);
 492
 493                                 io_block = next_log_block++;
 494                                 wrap(journal, next_log_block);
 495                                 err = jread(&obh, journal, io_block);
 496                                 if (err) {
 497                                         /* Recover what we can, but
 498                                          * report failure at the end. */
 499                                         success = err;
 500                                         printk (KERN_ERR
 501                                                 "JBD: IO error %d recovering "
 502                                                 "block %ld in log\n",
 503                                                 err, io_block);
 504                                 } else {
 505                                         unsigned long long blocknr;
 506
 507                                         J_ASSERT(obh != NULL);
 508                                         blocknr = read_tag_block(tag_bytes,
 509                                                                  tag);
 510
 511                                         /* If the block has been
 512                                          * revoked, then we're all done
 513                                          * here. */
 514                                         if (jbd2_journal_test_revoke
 515                                             (journal, blocknr,
 516                                              next_commit_ID)) {
 517                                                 brelse(obh);
 518                                                 ++info->nr_revoke_hits;
 519                                                 goto skip_write;
 520                                         }
 521
 522                                         /* Find a buffer for the new
 523                                          * data being restored */
 524                                         nbh = __getblk(journal->j_fs_dev,
 525                                                         blocknr,
 526                                                         journal->j_blocksize);
 527                                         if (nbh == NULL) {
 528                                                 printk(KERN_ERR
 529                                                        "JBD: Out of memory "
 530                                                        "during recovery.\n");
 531                                                 err = -ENOMEM;
 532                                                 brelse(bh);
 533                                                 brelse(obh);
 534                                                 goto failed;
 535                                         }
 536
 537                                         lock_buffer(nbh);
 538                                         memcpy(nbh->b_data, obh->b_data,
 539                                                         journal->j_blocksize);
 540                                         if (flags & JBD2_FLAG_ESCAPE) {
 541                                                 *((__be32 *)nbh->b_data) =
 542                                                 cpu_to_be32(JBD2_MAGIC_NUMBER);
 543                                         }
 544
 545                                         BUFFER_TRACE(nbh, "marking dirty");
 546                                         set_buffer_uptodate(nbh);
 547                                         mark_buffer_dirty(nbh);
 548                                         BUFFER_TRACE(nbh, "marking uptodate");
 549                                         ++info->nr_replays;
 550                                         /* ll_rw_block(WRITE, 1, &nbh); */
 551                                         unlock_buffer(nbh);
 552                                         brelse(obh);
 553                                         brelse(nbh);
 554                                 }
 555
 556                         skip_write:
 557                                 tagp += tag_bytes;
 558                                 if (!(flags & JBD2_FLAG_SAME_UUID))
 559                                         tagp += 16;
 560
 561                                 if (flags & JBD2_FLAG_LAST_TAG)
 562                                         break;
 563                         }
 564
 565                         brelse(bh);
 566                         continue;
 567
 568                 case JBD2_COMMIT_BLOCK:
 569                         /*     How to differentiate between interrupted commit
 570                          *               and journal corruption ?
 571                          *
 572                          * {nth transaction}
 573                          *        Checksum Verification Failed
 574                          *                       |
 575                          *               ____________________
 576                          *              |                    |
 577                          *      async_commit             sync_commit
 578                          *              |                    |
 579                          *              | GO TO NEXT    "Journal Corruption"
 580                          *              | TRANSACTION
 581                          *              |
 582                          * {(n+1)th transanction}
 583                          *              |
 584                          *       _______|______________
 585                          *      |                     |
 586                          * Commit block found   Commit block not found
 587                          *      |                     |
 588                          * "Journal Corruption"       |
 589                          *               _____________|_________
 590                          *              |                       |
 591                          *      nth trans corrupt       OR   nth trans
 592                          *      and (n+1)th interrupted     interrupted
 593                          *      before commit block
 594                          *      could reach the disk.
 595                          *      (Cannot find the difference in above
 596                          *       mentioned conditions. Hence assume
 597                          *       "Interrupted Commit".)
 598                          */
 599
 600                         /* Found an expected commit block: if checksums
 601                          * are present verify them in PASS_SCAN; else not
 602                          * much to do other than move on to the next sequence
 603                          * number. */
 604                         if (pass == PASS_SCAN &&
 605                             JBD2_HAS_COMPAT_FEATURE(journal,
 606                                     JBD2_FEATURE_COMPAT_CHECKSUM)) {
 607                                 int chksum_err, chksum_seen;
 608                                 struct commit_header *cbh =
 609                                         (struct commit_header *)bh->b_data;
 610                                 unsigned found_chksum =
 611                                         be32_to_cpu(cbh->h_chksum[0]);
 612
 613                                 chksum_err = chksum_seen = 0;
 614
 615                                 if (info->end_transaction) {
 616                                         journal->j_failed_commit =
 617                                                 info->end_transaction;
 618                                         brelse(bh);
 619                                         break;
 620                                 }
 621
 622                                 if (crc32_sum == found_chksum &&
 623                                     cbh->h_chksum_type == JBD2_CRC32_CHKSUM &&
 624                                     cbh->h_chksum_size ==
 625                                                 JBD2_CRC32_CHKSUM_SIZE)
 626                                        chksum_seen = 1;
 627                                 else if (!(cbh->h_chksum_type == 0 &&
 628                                              cbh->h_chksum_size == 0 &&
 629                                              found_chksum == 0 &&
 630                                              !chksum_seen))
 631                                 /*
 632                                  * If fs is mounted using an old kernel and then
 633                                  * kernel with journal_chksum is used then we
 634                                  * get a situation where the journal flag has
 635                                  * checksum flag set but checksums are not
 636                                  * present i.e chksum = 0, in the individual
 637                                  * commit blocks.
 638                                  * Hence to avoid checksum failures, in this
 639                                  * situation, this extra check is added.
 640                                  */
 641                                                 chksum_err = 1;
 642
 643                                 if (chksum_err) {
 644                                         info->end_transaction = next_commit_ID;
 645
 646                                         if (!JBD2_HAS_INCOMPAT_FEATURE(journal,
 647                                            JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)){
 648                                                 journal->j_failed_commit =
 649                                                         next_commit_ID;
 650                                                 brelse(bh);
 651                                                 break;
 652                                         }
 653                                 }
 654                                 crc32_sum = ~0;
 655                         }
 656                         brelse(bh);
 657                         next_commit_ID++;
 658                         continue;
 659
 660                 case JBD2_REVOKE_BLOCK:
 661                         /* If we aren't in the REVOKE pass, then we can
 662                          * just skip over this block. */
 663                         if (pass != PASS_REVOKE) {
 664                                 brelse(bh);
 665                                 continue;
 666                         }
 667
 668                         err = scan_revoke_records(journal, bh,
 669                                                   next_commit_ID, info);
 670                         brelse(bh);
 671                         if (err)
 672                                 goto failed;
 673                         continue;
 674
 675                 default:
 676                         jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
 677                                   blocktype);
 678                         brelse(bh);
 679                         goto done;
 680                 }
 681         }
 682
 683  done:
 684         /*
 685          * We broke out of the log scan loop: either we came to the
 686          * known end of the log or we found an unexpected block in the
 687          * log.  If the latter happened, then we know that the "current"
 688          * transaction marks the end of the valid log.
 689          */
 690
 691         if (pass == PASS_SCAN) {
 692                 if (!info->end_transaction)
 693                         info->end_transaction = next_commit_ID;
 694         } else {
 695                 /* It's really bad news if different passes end up at
 696                  * different places (but possible due to IO errors). */
 697                 if (info->end_transaction != next_commit_ID) {
 698                         printk (KERN_ERR "JBD: recovery pass %d ended at "
 699                                 "transaction %u, expected %u\n",
 700                                 pass, next_commit_ID, info->end_transaction);
 701                         if (!success)
 702                                 success = -EIO;
 703                 }
 704         }
 705
 706         return success;
 707
 708  failed:
 709         return err;
 710 }
 711
 712
 713 /* Scan a revoke record, marking all blocks mentioned as revoked. */
 714
 715 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
 716                                tid_t sequence, struct recovery_info *info)
 717 {
 718         jbd2_journal_revoke_header_t *header;
 719         int offset, max;
 720         int record_len = 4;
 721
 722         header = (jbd2_journal_revoke_header_t *) bh->b_data;
 723         offset = sizeof(jbd2_journal_revoke_header_t);
 724         max = be32_to_cpu(header->r_count);
 725
 726         if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
 727                 record_len = 8;
 728
 729         while (offset + record_len <= max) {
 730                 unsigned long long blocknr;
 731                 int err;
 732
 733                 if (record_len == 4)
 734                         blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
 735                 else
 736                         blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
 737                 offset += record_len;
 738                 err = jbd2_journal_set_revoke(journal, blocknr, sequence);
 739                 if (err)
 740                         return err;
 741                 ++info->nr_revokes;
 742         }
 743         return 0;
 744 }