linux/fs/jbd2/recovery.c
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   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 */
  30struct 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
  40enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY};
  41static int do_one_pass(journal_t *journal,
  42                                struct recovery_info *info, enum passtype pass);
  43static 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 */
  49static 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
  69static 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
 118failed:
 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
 131static 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
 181static 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)                                              \
 208do {                                                                    \
 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 */
 225int 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 */
 285int 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
 314static 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 */
 326static 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
 354static 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
 715static 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}
 745
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