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/slab.h>
  24 #include <linux/crc32.h>
  25 #endif
  26
  27 /*
  28  * Maintain information about the progress of the recovery job, so that
  29  * the different passes can carry information between them.
  30  */
  31 struct recovery_info
  32 {
  33         tid_t           start_transaction;
  34         tid_t           end_transaction;
  35
  36         int             nr_replays;
  37         int             nr_revokes;
  38         int             nr_revoke_hits;
  39 };
  40
  41 enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY};
  42 static int do_one_pass(journal_t *journal,
  43                                 struct recovery_info *info, enum passtype pass);
  44 static int scan_revoke_records(journal_t *, struct buffer_head *,
  45                                 tid_t, struct recovery_info *);
  46
  47 #ifdef __KERNEL__
  48
  49 /* Release readahead buffers after use */
  50 static void journal_brelse_array(struct buffer_head *b[], int n)
  51 {
  52         while (--n >= 0)
  53                 brelse (b[n]);
  54 }
  55
  56
  57 /*
  58  * When reading from the journal, we are going through the block device
  59  * layer directly and so there is no readahead being done for us.  We
  60  * need to implement any readahead ourselves if we want it to happen at
  61  * all.  Recovery is basically one long sequential read, so make sure we
  62  * do the IO in reasonably large chunks.
  63  *
  64  * This is not so critical that we need to be enormously clever about
  65  * the readahead size, though.  128K is a purely arbitrary, good-enough
  66  * fixed value.
  67  */
  68
  69 #define MAXBUF 8
  70 static int do_readahead(journal_t *journal, unsigned int start)
  71 {
  72         int err;
  73         unsigned int max, nbufs, next;
  74         unsigned long long blocknr;
  75         struct buffer_head *bh;
  76
  77         struct buffer_head * bufs[MAXBUF];
  78
  79         /* Do up to 128K of readahead */
  80         max = start + (128 * 1024 / journal->j_blocksize);
  81         if (max > journal->j_maxlen)
  82                 max = journal->j_maxlen;
  83
  84         /* Do the readahead itself.  We'll submit MAXBUF buffer_heads at
  85          * a time to the block device IO layer. */
  86
  87         nbufs = 0;
  88
  89         for (next = start; next < max; next++) {
  90                 err = jbd2_journal_bmap(journal, next, &blocknr);
  91
  92                 if (err) {
  93                         printk (KERN_ERR "JBD: bad block at offset %u\n",
  94                                 next);
  95                         goto failed;
  96                 }
  97
  98                 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
  99                 if (!bh) {
 100                         err = -ENOMEM;
 101                         goto failed;
 102                 }
 103
 104                 if (!buffer_uptodate(bh) && !buffer_locked(bh)) {
 105                         bufs[nbufs++] = bh;
 106                         if (nbufs == MAXBUF) {
 107                                 ll_rw_block(READ, nbufs, bufs);
 108                                 journal_brelse_array(bufs, nbufs);
 109                                 nbufs = 0;
 110                         }
 111                 } else
 112                         brelse(bh);
 113         }
 114
 115         if (nbufs)
 116                 ll_rw_block(READ, nbufs, bufs);
 117         err = 0;
 118
 119 failed:
 120         if (nbufs)
 121                 journal_brelse_array(bufs, nbufs);
 122         return err;
 123 }
 124
 125 #endif /* __KERNEL__ */
 126
 127
 128 /*
 129  * Read a block from the journal
 130  */
 131
 132 static int jread(struct buffer_head **bhp, journal_t *journal,
 133                  unsigned int offset)
 134 {
 135         int err;
 136         unsigned long long blocknr;
 137         struct buffer_head *bh;
 138
 139         *bhp = NULL;
 140
 141         if (offset >= journal->j_maxlen) {
 142                 printk(KERN_ERR "JBD: corrupted journal superblock\n");
 143                 return -EIO;
 144         }
 145
 146         err = jbd2_journal_bmap(journal, offset, &blocknr);
 147
 148         if (err) {
 149                 printk (KERN_ERR "JBD: bad block at offset %u\n",
 150                         offset);
 151                 return err;
 152         }
 153
 154         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
 155         if (!bh)
 156                 return -ENOMEM;
 157
 158         if (!buffer_uptodate(bh)) {
 159                 /* If this is a brand new buffer, start readahead.
 160                    Otherwise, we assume we are already reading it.  */
 161                 if (!buffer_req(bh))
 162                         do_readahead(journal, offset);
 163                 wait_on_buffer(bh);
 164         }
 165
 166         if (!buffer_uptodate(bh)) {
 167                 printk (KERN_ERR "JBD: Failed to read block at offset %u\n",
 168                         offset);
 169                 brelse(bh);
 170                 return -EIO;
 171         }
 172
 173         *bhp = bh;
 174         return 0;
 175 }
 176
 177
 178 /*
 179  * Count the number of in-use tags in a journal descriptor block.
 180  */
 181
 182 static int count_tags(journal_t *journal, struct buffer_head *bh)
 183 {
 184         char *                  tagp;
 185         journal_block_tag_t *   tag;
 186         int                     nr = 0, size = journal->j_blocksize;
 187         int                     tag_bytes = journal_tag_bytes(journal);
 188
 189         tagp = &bh->b_data[sizeof(journal_header_t)];
 190
 191         while ((tagp - bh->b_data + tag_bytes) <= size) {
 192                 tag = (journal_block_tag_t *) tagp;
 193
 194                 nr++;
 195                 tagp += tag_bytes;
 196                 if (!(tag->t_flags & cpu_to_be32(JBD2_FLAG_SAME_UUID)))
 197                         tagp += 16;
 198
 199                 if (tag->t_flags & cpu_to_be32(JBD2_FLAG_LAST_TAG))
 200                         break;
 201         }
 202
 203         return nr;
 204 }
 205
 206
 207 /* Make sure we wrap around the log correctly! */
 208 #define wrap(journal, var)                                              \
 209 do {                                                                    \
 210         if (var >= (journal)->j_last)                                   \
 211                 var -= ((journal)->j_last - (journal)->j_first);        \
 212 } while (0)
 213
 214 /**
 215  * jbd2_journal_recover - recovers a on-disk journal
 216  * @journal: the journal to recover
 217  *
 218  * The primary function for recovering the log contents when mounting a
 219  * journaled device.
 220  *
 221  * Recovery is done in three passes.  In the first pass, we look for the
 222  * end of the log.  In the second, we assemble the list of revoke
 223  * blocks.  In the third and final pass, we replay any un-revoked blocks
 224  * in the log.
 225  */
 226 int jbd2_journal_recover(journal_t *journal)
 227 {
 228         int                     err, err2;
 229         journal_superblock_t *  sb;
 230
 231         struct recovery_info    info;
 232
 233         memset(&info, 0, sizeof(info));
 234         sb = journal->j_superblock;
 235
 236         /*
 237          * The journal superblock's s_start field (the current log head)
 238          * is always zero if, and only if, the journal was cleanly
 239          * unmounted.
 240          */
 241
 242         if (!sb->s_start) {
 243                 jbd_debug(1, "No recovery required, last transaction %d\n",
 244                           be32_to_cpu(sb->s_sequence));
 245                 journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
 246                 return 0;
 247         }
 248
 249         err = do_one_pass(journal, &info, PASS_SCAN);
 250         if (!err)
 251                 err = do_one_pass(journal, &info, PASS_REVOKE);
 252         if (!err)
 253                 err = do_one_pass(journal, &info, PASS_REPLAY);
 254
 255         jbd_debug(1, "JBD: recovery, exit status %d, "
 256                   "recovered transactions %u to %u\n",
 257                   err, info.start_transaction, info.end_transaction);
 258         jbd_debug(1, "JBD: Replayed %d and revoked %d/%d blocks\n",
 259                   info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
 260
 261         /* Restart the log at the next transaction ID, thus invalidating
 262          * any existing commit records in the log. */
 263         journal->j_transaction_sequence = ++info.end_transaction;
 264
 265         jbd2_journal_clear_revoke(journal);
 266         err2 = sync_blockdev(journal->j_fs_dev);
 267         if (!err)
 268                 err = err2;
 269
 270         return err;
 271 }
 272
 273 /**
 274  * jbd2_journal_skip_recovery - Start journal and wipe exiting records
 275  * @journal: journal to startup
 276  *
 277  * Locate any valid recovery information from the journal and set up the
 278  * journal structures in memory to ignore it (presumably because the
 279  * caller has evidence that it is out of date).
 280  * This function does'nt appear to be exorted..
 281  *
 282  * We perform one pass over the journal to allow us to tell the user how
 283  * much recovery information is being erased, and to let us initialise
 284  * the journal transaction sequence numbers to the next unused ID.
 285  */
 286 int jbd2_journal_skip_recovery(journal_t *journal)
 287 {
 288         int                     err;
 289         journal_superblock_t *  sb;
 290
 291         struct recovery_info    info;
 292
 293         memset (&info, 0, sizeof(info));
 294         sb = journal->j_superblock;
 295
 296         err = do_one_pass(journal, &info, PASS_SCAN);
 297
 298         if (err) {
 299                 printk(KERN_ERR "JBD: error %d scanning journal\n", err);
 300                 ++journal->j_transaction_sequence;
 301         } else {
 302 #ifdef CONFIG_JBD2_DEBUG
 303                 int dropped = info.end_transaction - be32_to_cpu(sb->s_sequence);
 304 #endif
 305                 jbd_debug(1,
 306                           "JBD: ignoring %d transaction%s from the journal.\n",
 307                           dropped, (dropped == 1) ? "" : "s");
 308                 journal->j_transaction_sequence = ++info.end_transaction;
 309         }
 310
 311         journal->j_tail = 0;
 312         return err;
 313 }
 314
 315 static inline unsigned long long read_tag_block(int tag_bytes, journal_block_tag_t *tag)
 316 {
 317         unsigned long long block = be32_to_cpu(tag->t_blocknr);
 318         if (tag_bytes > JBD2_TAG_SIZE32)
 319                 block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
 320         return block;
 321 }
 322
 323 /*
 324  * calc_chksums calculates the checksums for the blocks described in the
 325  * descriptor block.
 326  */
 327 static int calc_chksums(journal_t *journal, struct buffer_head *bh,
 328                         unsigned long *next_log_block, __u32 *crc32_sum)
 329 {
 330         int i, num_blks, err;
 331         unsigned long io_block;
 332         struct buffer_head *obh;
 333
 334         num_blks = count_tags(journal, bh);
 335         /* Calculate checksum of the descriptor block. */
 336         *crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
 337
 338         for (i = 0; i < num_blks; i++) {
 339                 io_block = (*next_log_block)++;
 340                 wrap(journal, *next_log_block);
 341                 err = jread(&obh, journal, io_block);
 342                 if (err) {
 343                         printk(KERN_ERR "JBD: IO error %d recovering block "
 344                                 "%lu in log\n", err, io_block);
 345                         return 1;
 346                 } else {
 347                         *crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
 348                                      obh->b_size);
 349                 }
 350                 put_bh(obh);
 351         }
 352         return 0;
 353 }
 354
 355 static int do_one_pass(journal_t *journal,
 356                         struct recovery_info *info, enum passtype pass)
 357 {
 358         unsigned int            first_commit_ID, next_commit_ID;
 359         unsigned long           next_log_block;
 360         int                     err, success = 0;
 361         journal_superblock_t *  sb;
 362         journal_header_t *      tmp;
 363         struct buffer_head *    bh;
 364         unsigned int            sequence;
 365         int                     blocktype;
 366         int                     tag_bytes = journal_tag_bytes(journal);
 367         __u32                   crc32_sum = ~0; /* Transactional Checksums */
 368
 369         /* Precompute the maximum metadata descriptors in a descriptor block */
 370         int                     MAX_BLOCKS_PER_DESC;
 371         MAX_BLOCKS_PER_DESC = ((journal->j_blocksize-sizeof(journal_header_t))
 372                                / tag_bytes);
 373
 374         /*
 375          * First thing is to establish what we expect to find in the log
 376          * (in terms of transaction IDs), and where (in terms of log
 377          * block offsets): query the superblock.
 378          */
 379
 380         sb = journal->j_superblock;
 381         next_commit_ID = be32_to_cpu(sb->s_sequence);
 382         next_log_block = be32_to_cpu(sb->s_start);
 383
 384         first_commit_ID = next_commit_ID;
 385         if (pass == PASS_SCAN)
 386                 info->start_transaction = first_commit_ID;
 387
 388         jbd_debug(1, "Starting recovery pass %d\n", pass);
 389
 390         /*
 391          * Now we walk through the log, transaction by transaction,
 392          * making sure that each transaction has a commit block in the
 393          * expected place.  Each complete transaction gets replayed back
 394          * into the main filesystem.
 395          */
 396
 397         while (1) {
 398                 int                     flags;
 399                 char *                  tagp;
 400                 journal_block_tag_t *   tag;
 401                 struct buffer_head *    obh;
 402                 struct buffer_head *    nbh;
 403
 404                 cond_resched();
 405
 406                 /* If we already know where to stop the log traversal,
 407                  * check right now that we haven't gone past the end of
 408                  * the log. */
 409
 410                 if (pass != PASS_SCAN)
 411                         if (tid_geq(next_commit_ID, info->end_transaction))
 412                                 break;
 413
 414                 jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
 415                           next_commit_ID, next_log_block, journal->j_last);
 416
 417                 /* Skip over each chunk of the transaction looking
 418                  * either the next descriptor block or the final commit
 419                  * record. */
 420
 421                 jbd_debug(3, "JBD: checking block %ld\n", next_log_block);
 422                 err = jread(&bh, journal, next_log_block);
 423                 if (err)
 424                         goto failed;
 425
 426                 next_log_block++;
 427                 wrap(journal, next_log_block);
 428
 429                 /* What kind of buffer is it?
 430                  *
 431                  * If it is a descriptor block, check that it has the
 432                  * expected sequence number.  Otherwise, we're all done
 433                  * here. */
 434
 435                 tmp = (journal_header_t *)bh->b_data;
 436
 437                 if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
 438                         brelse(bh);
 439                         break;
 440                 }
 441
 442                 blocktype = be32_to_cpu(tmp->h_blocktype);
 443                 sequence = be32_to_cpu(tmp->h_sequence);
 444                 jbd_debug(3, "Found magic %d, sequence %d\n",
 445                           blocktype, sequence);
 446
 447                 if (sequence != next_commit_ID) {
 448                         brelse(bh);
 449                         break;
 450                 }
 451
 452                 /* OK, we have a valid descriptor block which matches
 453                  * all of the sequence number checks.  What are we going
 454                  * to do with it?  That depends on the pass... */
 455
 456                 switch(blocktype) {
 457                 case JBD2_DESCRIPTOR_BLOCK:
 458                         /* If it is a valid descriptor block, replay it
 459                          * in pass REPLAY; if journal_checksums enabled, then
 460                          * calculate checksums in PASS_SCAN, otherwise,
 461                          * just skip over the blocks it describes. */
 462                         if (pass != PASS_REPLAY) {
 463                                 if (pass == PASS_SCAN &&
 464                                     JBD2_HAS_COMPAT_FEATURE(journal,
 465                                             JBD2_FEATURE_COMPAT_CHECKSUM) &&
 466                                     !info->end_transaction) {
 467                                         if (calc_chksums(journal, bh,
 468                                                         &next_log_block,
 469                                                         &crc32_sum)) {
 470                                                 put_bh(bh);
 471                                                 break;
 472                                         }
 473                                         put_bh(bh);
 474                                         continue;
 475                                 }
 476                                 next_log_block += count_tags(journal, bh);
 477                                 wrap(journal, next_log_block);
 478                                 put_bh(bh);
 479                                 continue;
 480                         }
 481
 482                         /* A descriptor block: we can now write all of
 483                          * the data blocks.  Yay, useful work is finally
 484                          * getting done here! */
 485
 486                         tagp = &bh->b_data[sizeof(journal_header_t)];
 487                         while ((tagp - bh->b_data + tag_bytes)
 488                                <= journal->j_blocksize) {
 489                                 unsigned long io_block;
 490
 491                                 tag = (journal_block_tag_t *) tagp;
 492                                 flags = be32_to_cpu(tag->t_flags);
 493
 494                                 io_block = next_log_block++;
 495                                 wrap(journal, next_log_block);
 496                                 err = jread(&obh, journal, io_block);
 497                                 if (err) {
 498                                         /* Recover what we can, but
 499                                          * report failure at the end. */
 500                                         success = err;
 501                                         printk (KERN_ERR
 502                                                 "JBD: IO error %d recovering "
 503                                                 "block %ld in log\n",
 504                                                 err, io_block);
 505                                 } else {
 506                                         unsigned long long blocknr;
 507
 508                                         J_ASSERT(obh != NULL);
 509                                         blocknr = read_tag_block(tag_bytes,
 510                                                                  tag);
 511
 512                                         /* If the block has been
 513                                          * revoked, then we're all done
 514                                          * here. */
 515                                         if (jbd2_journal_test_revoke
 516                                             (journal, blocknr,
 517                                              next_commit_ID)) {
 518                                                 brelse(obh);
 519                                                 ++info->nr_revoke_hits;
 520                                                 goto skip_write;
 521                                         }
 522
 523                                         /* Find a buffer for the new
 524                                          * data being restored */
 525                                         nbh = __getblk(journal->j_fs_dev,
 526                                                         blocknr,
 527                                                         journal->j_blocksize);
 528                                         if (nbh == NULL) {
 529                                                 printk(KERN_ERR
 530                                                        "JBD: Out of memory "
 531                                                        "during recovery.\n");
 532                                                 err = -ENOMEM;
 533                                                 brelse(bh);
 534                                                 brelse(obh);
 535                                                 goto failed;
 536                                         }
 537
 538                                         lock_buffer(nbh);
 539                                         memcpy(nbh->b_data, obh->b_data,
 540                                                         journal->j_blocksize);
 541                                         if (flags & JBD2_FLAG_ESCAPE) {
 542                                                 *((__be32 *)nbh->b_data) =
 543                                                 cpu_to_be32(JBD2_MAGIC_NUMBER);
 544                                         }
 545
 546                                         BUFFER_TRACE(nbh, "marking dirty");
 547                                         set_buffer_uptodate(nbh);
 548                                         mark_buffer_dirty(nbh);
 549                                         BUFFER_TRACE(nbh, "marking uptodate");
 550                                         ++info->nr_replays;
 551                                         /* ll_rw_block(WRITE, 1, &nbh); */
 552                                         unlock_buffer(nbh);
 553                                         brelse(obh);
 554                                         brelse(nbh);
 555                                 }
 556
 557                         skip_write:
 558                                 tagp += tag_bytes;
 559                                 if (!(flags & JBD2_FLAG_SAME_UUID))
 560                                         tagp += 16;
 561
 562                                 if (flags & JBD2_FLAG_LAST_TAG)
 563                                         break;
 564                         }
 565
 566                         brelse(bh);
 567                         continue;
 568
 569                 case JBD2_COMMIT_BLOCK:
 570                         /*     How to differentiate between interrupted commit
 571                          *               and journal corruption ?
 572                          *
 573                          * {nth transaction}
 574                          *        Checksum Verification Failed
 575                          *                       |
 576                          *               ____________________
 577                          *              |                    |
 578                          *      async_commit             sync_commit
 579                          *              |                    |
 580                          *              | GO TO NEXT    "Journal Corruption"
 581                          *              | TRANSACTION
 582                          *              |
 583                          * {(n+1)th transanction}
 584                          *              |
 585                          *       _______|______________
 586                          *      |                     |
 587                          * Commit block found   Commit block not found
 588                          *      |                     |
 589                          * "Journal Corruption"       |
 590                          *               _____________|_________
 591                          *              |                       |
 592                          *      nth trans corrupt       OR   nth trans
 593                          *      and (n+1)th interrupted     interrupted
 594                          *      before commit block
 595                          *      could reach the disk.
 596                          *      (Cannot find the difference in above
 597                          *       mentioned conditions. Hence assume
 598                          *       "Interrupted Commit".)
 599                          */
 600
 601                         /* Found an expected commit block: if checksums
 602                          * are present verify them in PASS_SCAN; else not
 603                          * much to do other than move on to the next sequence
 604                          * number. */
 605                         if (pass == PASS_SCAN &&
 606                             JBD2_HAS_COMPAT_FEATURE(journal,
 607                                     JBD2_FEATURE_COMPAT_CHECKSUM)) {
 608                                 int chksum_err, chksum_seen;
 609                                 struct commit_header *cbh =
 610                                         (struct commit_header *)bh->b_data;
 611                                 unsigned found_chksum =
 612                                         be32_to_cpu(cbh->h_chksum[0]);
 613
 614                                 chksum_err = chksum_seen = 0;
 615
 616                                 if (info->end_transaction) {
 617                                         journal->j_failed_commit =
 618                                                 info->end_transaction;
 619                                         brelse(bh);
 620                                         break;
 621                                 }
 622
 623                                 if (crc32_sum == found_chksum &&
 624                                     cbh->h_chksum_type == JBD2_CRC32_CHKSUM &&
 625                                     cbh->h_chksum_size ==
 626                                                 JBD2_CRC32_CHKSUM_SIZE)
 627                                        chksum_seen = 1;
 628                                 else if (!(cbh->h_chksum_type == 0 &&
 629                                              cbh->h_chksum_size == 0 &&
 630                                              found_chksum == 0 &&
 631                                              !chksum_seen))
 632                                 /*
 633                                  * If fs is mounted using an old kernel and then
 634                                  * kernel with journal_chksum is used then we
 635                                  * get a situation where the journal flag has
 636                                  * checksum flag set but checksums are not
 637                                  * present i.e chksum = 0, in the individual
 638                                  * commit blocks.
 639                                  * Hence to avoid checksum failures, in this
 640                                  * situation, this extra check is added.
 641                                  */
 642                                                 chksum_err = 1;
 643
 644                                 if (chksum_err) {
 645                                         info->end_transaction = next_commit_ID;
 646
 647                                         if (!JBD2_HAS_INCOMPAT_FEATURE(journal,
 648                                            JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)){
 649                                                 journal->j_failed_commit =
 650                                                         next_commit_ID;
 651                                                 brelse(bh);
 652                                                 break;
 653                                         }
 654                                 }
 655                                 crc32_sum = ~0;
 656                         }
 657                         brelse(bh);
 658                         next_commit_ID++;
 659                         continue;
 660
 661                 case JBD2_REVOKE_BLOCK:
 662                         /* If we aren't in the REVOKE pass, then we can
 663                          * just skip over this block. */
 664                         if (pass != PASS_REVOKE) {
 665                                 brelse(bh);
 666                                 continue;
 667                         }
 668
 669                         err = scan_revoke_records(journal, bh,
 670                                                   next_commit_ID, info);
 671                         brelse(bh);
 672                         if (err)
 673                                 goto failed;
 674                         continue;
 675
 676                 default:
 677                         jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
 678                                   blocktype);
 679                         brelse(bh);
 680                         goto done;
 681                 }
 682         }
 683
 684  done:
 685         /*
 686          * We broke out of the log scan loop: either we came to the
 687          * known end of the log or we found an unexpected block in the
 688          * log.  If the latter happened, then we know that the "current"
 689          * transaction marks the end of the valid log.
 690          */
 691
 692         if (pass == PASS_SCAN) {
 693                 if (!info->end_transaction)
 694                         info->end_transaction = next_commit_ID;
 695         } else {
 696                 /* It's really bad news if different passes end up at
 697                  * different places (but possible due to IO errors). */
 698                 if (info->end_transaction != next_commit_ID) {
 699                         printk (KERN_ERR "JBD: recovery pass %d ended at "
 700                                 "transaction %u, expected %u\n",
 701                                 pass, next_commit_ID, info->end_transaction);
 702                         if (!success)
 703                                 success = -EIO;
 704                 }
 705         }
 706
 707         return success;
 708
 709  failed:
 710         return err;
 711 }
 712
 713
 714 /* Scan a revoke record, marking all blocks mentioned as revoked. */
 715
 716 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
 717                                tid_t sequence, struct recovery_info *info)
 718 {
 719         jbd2_journal_revoke_header_t *header;
 720         int offset, max;
 721         int record_len = 4;
 722
 723         header = (jbd2_journal_revoke_header_t *) bh->b_data;
 724         offset = sizeof(jbd2_journal_revoke_header_t);
 725         max = be32_to_cpu(header->r_count);
 726
 727         if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
 728                 record_len = 8;
 729
 730         while (offset + record_len <= max) {
 731                 unsigned long long blocknr;
 732                 int err;
 733
 734                 if (record_len == 4)
 735                         blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
 736                 else
 737                         blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
 738                 offset += record_len;
 739                 err = jbd2_journal_set_revoke(journal, blocknr, sequence);
 740                 if (err)
 741                         return err;
 742                 ++info->nr_revokes;
 743         }
 744         return 0;
 745 }