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#include <linux/blkdev.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 */
  31struct 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
  41enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY};
  42static int do_one_pass(journal_t *journal,
  43                                struct recovery_info *info, enum passtype pass);
  44static 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 */
  50static 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
  70static 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 "JBD2: 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
 119failed:
 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
 132static 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 "JBD2: 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 "JBD2: 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 "JBD2: 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
 177static int jbd2_descr_block_csum_verify(journal_t *j,
 178                                        void *buf)
 179{
 180        struct jbd2_journal_block_tail *tail;
 181        __u32 provided, calculated;
 182
 183        if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 184                return 1;
 185
 186        tail = (struct jbd2_journal_block_tail *)(buf + j->j_blocksize -
 187                        sizeof(struct jbd2_journal_block_tail));
 188        provided = tail->t_checksum;
 189        tail->t_checksum = 0;
 190        calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 191        tail->t_checksum = provided;
 192
 193        provided = be32_to_cpu(provided);
 194        return provided == calculated;
 195}
 196
 197/*
 198 * Count the number of in-use tags in a journal descriptor block.
 199 */
 200
 201static int count_tags(journal_t *journal, struct buffer_head *bh)
 202{
 203        char *                  tagp;
 204        journal_block_tag_t *   tag;
 205        int                     nr = 0, size = journal->j_blocksize;
 206        int                     tag_bytes = journal_tag_bytes(journal);
 207
 208        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 209                size -= sizeof(struct jbd2_journal_block_tail);
 210
 211        tagp = &bh->b_data[sizeof(journal_header_t)];
 212
 213        while ((tagp - bh->b_data + tag_bytes) <= size) {
 214                tag = (journal_block_tag_t *) tagp;
 215
 216                nr++;
 217                tagp += tag_bytes;
 218                if (!(tag->t_flags & cpu_to_be16(JBD2_FLAG_SAME_UUID)))
 219                        tagp += 16;
 220
 221                if (tag->t_flags & cpu_to_be16(JBD2_FLAG_LAST_TAG))
 222                        break;
 223        }
 224
 225        return nr;
 226}
 227
 228
 229/* Make sure we wrap around the log correctly! */
 230#define wrap(journal, var)                                              \
 231do {                                                                    \
 232        if (var >= (journal)->j_last)                                   \
 233                var -= ((journal)->j_last - (journal)->j_first);        \
 234} while (0)
 235
 236/**
 237 * jbd2_journal_recover - recovers a on-disk journal
 238 * @journal: the journal to recover
 239 *
 240 * The primary function for recovering the log contents when mounting a
 241 * journaled device.
 242 *
 243 * Recovery is done in three passes.  In the first pass, we look for the
 244 * end of the log.  In the second, we assemble the list of revoke
 245 * blocks.  In the third and final pass, we replay any un-revoked blocks
 246 * in the log.
 247 */
 248int jbd2_journal_recover(journal_t *journal)
 249{
 250        int                     err, err2;
 251        journal_superblock_t *  sb;
 252
 253        struct recovery_info    info;
 254
 255        memset(&info, 0, sizeof(info));
 256        sb = journal->j_superblock;
 257
 258        /*
 259         * The journal superblock's s_start field (the current log head)
 260         * is always zero if, and only if, the journal was cleanly
 261         * unmounted.
 262         */
 263
 264        if (!sb->s_start) {
 265                jbd_debug(1, "No recovery required, last transaction %d\n",
 266                          be32_to_cpu(sb->s_sequence));
 267                journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
 268                return 0;
 269        }
 270
 271        err = do_one_pass(journal, &info, PASS_SCAN);
 272        if (!err)
 273                err = do_one_pass(journal, &info, PASS_REVOKE);
 274        if (!err)
 275                err = do_one_pass(journal, &info, PASS_REPLAY);
 276
 277        jbd_debug(1, "JBD2: recovery, exit status %d, "
 278                  "recovered transactions %u to %u\n",
 279                  err, info.start_transaction, info.end_transaction);
 280        jbd_debug(1, "JBD2: Replayed %d and revoked %d/%d blocks\n",
 281                  info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
 282
 283        /* Restart the log at the next transaction ID, thus invalidating
 284         * any existing commit records in the log. */
 285        journal->j_transaction_sequence = ++info.end_transaction;
 286
 287        jbd2_journal_clear_revoke(journal);
 288        err2 = sync_blockdev(journal->j_fs_dev);
 289        if (!err)
 290                err = err2;
 291        /* Make sure all replayed data is on permanent storage */
 292        if (journal->j_flags & JBD2_BARRIER)
 293                blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL);
 294        return err;
 295}
 296
 297/**
 298 * jbd2_journal_skip_recovery - Start journal and wipe exiting records
 299 * @journal: journal to startup
 300 *
 301 * Locate any valid recovery information from the journal and set up the
 302 * journal structures in memory to ignore it (presumably because the
 303 * caller has evidence that it is out of date).
 304 * This function does'nt appear to be exorted..
 305 *
 306 * We perform one pass over the journal to allow us to tell the user how
 307 * much recovery information is being erased, and to let us initialise
 308 * the journal transaction sequence numbers to the next unused ID.
 309 */
 310int jbd2_journal_skip_recovery(journal_t *journal)
 311{
 312        int                     err;
 313
 314        struct recovery_info    info;
 315
 316        memset (&info, 0, sizeof(info));
 317
 318        err = do_one_pass(journal, &info, PASS_SCAN);
 319
 320        if (err) {
 321                printk(KERN_ERR "JBD2: error %d scanning journal\n", err);
 322                ++journal->j_transaction_sequence;
 323        } else {
 324#ifdef CONFIG_JBD2_DEBUG
 325                int dropped = info.end_transaction - 
 326                        be32_to_cpu(journal->j_superblock->s_sequence);
 327                jbd_debug(1,
 328                          "JBD2: ignoring %d transaction%s from the journal.\n",
 329                          dropped, (dropped == 1) ? "" : "s");
 330#endif
 331                journal->j_transaction_sequence = ++info.end_transaction;
 332        }
 333
 334        journal->j_tail = 0;
 335        return err;
 336}
 337
 338static inline unsigned long long read_tag_block(int tag_bytes, journal_block_tag_t *tag)
 339{
 340        unsigned long long block = be32_to_cpu(tag->t_blocknr);
 341        if (tag_bytes > JBD2_TAG_SIZE32)
 342                block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
 343        return block;
 344}
 345
 346/*
 347 * calc_chksums calculates the checksums for the blocks described in the
 348 * descriptor block.
 349 */
 350static int calc_chksums(journal_t *journal, struct buffer_head *bh,
 351                        unsigned long *next_log_block, __u32 *crc32_sum)
 352{
 353        int i, num_blks, err;
 354        unsigned long io_block;
 355        struct buffer_head *obh;
 356
 357        num_blks = count_tags(journal, bh);
 358        /* Calculate checksum of the descriptor block. */
 359        *crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
 360
 361        for (i = 0; i < num_blks; i++) {
 362                io_block = (*next_log_block)++;
 363                wrap(journal, *next_log_block);
 364                err = jread(&obh, journal, io_block);
 365                if (err) {
 366                        printk(KERN_ERR "JBD2: IO error %d recovering block "
 367                                "%lu in log\n", err, io_block);
 368                        return 1;
 369                } else {
 370                        *crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
 371                                     obh->b_size);
 372                }
 373                put_bh(obh);
 374        }
 375        return 0;
 376}
 377
 378static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
 379{
 380        struct commit_header *h;
 381        __u32 provided, calculated;
 382
 383        if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 384                return 1;
 385
 386        h = buf;
 387        provided = h->h_chksum[0];
 388        h->h_chksum[0] = 0;
 389        calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 390        h->h_chksum[0] = provided;
 391
 392        provided = be32_to_cpu(provided);
 393        return provided == calculated;
 394}
 395
 396static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
 397                                      void *buf, __u32 sequence)
 398{
 399        __u32 provided, calculated;
 400
 401        if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 402                return 1;
 403
 404        sequence = cpu_to_be32(sequence);
 405        calculated = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&sequence,
 406                                 sizeof(sequence));
 407        calculated = jbd2_chksum(j, calculated, buf, j->j_blocksize);
 408        provided = be32_to_cpu(tag->t_checksum);
 409
 410        return provided == cpu_to_be32(calculated);
 411}
 412
 413static int do_one_pass(journal_t *journal,
 414                        struct recovery_info *info, enum passtype pass)
 415{
 416        unsigned int            first_commit_ID, next_commit_ID;
 417        unsigned long           next_log_block;
 418        int                     err, success = 0;
 419        journal_superblock_t *  sb;
 420        journal_header_t *      tmp;
 421        struct buffer_head *    bh;
 422        unsigned int            sequence;
 423        int                     blocktype;
 424        int                     tag_bytes = journal_tag_bytes(journal);
 425        __u32                   crc32_sum = ~0; /* Transactional Checksums */
 426        int                     descr_csum_size = 0;
 427
 428        /*
 429         * First thing is to establish what we expect to find in the log
 430         * (in terms of transaction IDs), and where (in terms of log
 431         * block offsets): query the superblock.
 432         */
 433
 434        sb = journal->j_superblock;
 435        next_commit_ID = be32_to_cpu(sb->s_sequence);
 436        next_log_block = be32_to_cpu(sb->s_start);
 437
 438        first_commit_ID = next_commit_ID;
 439        if (pass == PASS_SCAN)
 440                info->start_transaction = first_commit_ID;
 441
 442        jbd_debug(1, "Starting recovery pass %d\n", pass);
 443
 444        /*
 445         * Now we walk through the log, transaction by transaction,
 446         * making sure that each transaction has a commit block in the
 447         * expected place.  Each complete transaction gets replayed back
 448         * into the main filesystem.
 449         */
 450
 451        while (1) {
 452                int                     flags;
 453                char *                  tagp;
 454                journal_block_tag_t *   tag;
 455                struct buffer_head *    obh;
 456                struct buffer_head *    nbh;
 457
 458                cond_resched();
 459
 460                /* If we already know where to stop the log traversal,
 461                 * check right now that we haven't gone past the end of
 462                 * the log. */
 463
 464                if (pass != PASS_SCAN)
 465                        if (tid_geq(next_commit_ID, info->end_transaction))
 466                                break;
 467
 468                jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
 469                          next_commit_ID, next_log_block, journal->j_last);
 470
 471                /* Skip over each chunk of the transaction looking
 472                 * either the next descriptor block or the final commit
 473                 * record. */
 474
 475                jbd_debug(3, "JBD2: checking block %ld\n", next_log_block);
 476                err = jread(&bh, journal, next_log_block);
 477                if (err)
 478                        goto failed;
 479
 480                next_log_block++;
 481                wrap(journal, next_log_block);
 482
 483                /* What kind of buffer is it?
 484                 *
 485                 * If it is a descriptor block, check that it has the
 486                 * expected sequence number.  Otherwise, we're all done
 487                 * here. */
 488
 489                tmp = (journal_header_t *)bh->b_data;
 490
 491                if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
 492                        brelse(bh);
 493                        break;
 494                }
 495
 496                blocktype = be32_to_cpu(tmp->h_blocktype);
 497                sequence = be32_to_cpu(tmp->h_sequence);
 498                jbd_debug(3, "Found magic %d, sequence %d\n",
 499                          blocktype, sequence);
 500
 501                if (sequence != next_commit_ID) {
 502                        brelse(bh);
 503                        break;
 504                }
 505
 506                /* OK, we have a valid descriptor block which matches
 507                 * all of the sequence number checks.  What are we going
 508                 * to do with it?  That depends on the pass... */
 509
 510                switch(blocktype) {
 511                case JBD2_DESCRIPTOR_BLOCK:
 512                        /* Verify checksum first */
 513                        if (JBD2_HAS_INCOMPAT_FEATURE(journal,
 514                                        JBD2_FEATURE_INCOMPAT_CSUM_V2))
 515                                descr_csum_size =
 516                                        sizeof(struct jbd2_journal_block_tail);
 517                        if (descr_csum_size > 0 &&
 518                            !jbd2_descr_block_csum_verify(journal,
 519                                                          bh->b_data)) {
 520                                err = -EIO;
 521                                goto failed;
 522                        }
 523
 524                        /* If it is a valid descriptor block, replay it
 525                         * in pass REPLAY; if journal_checksums enabled, then
 526                         * calculate checksums in PASS_SCAN, otherwise,
 527                         * just skip over the blocks it describes. */
 528                        if (pass != PASS_REPLAY) {
 529                                if (pass == PASS_SCAN &&
 530                                    JBD2_HAS_COMPAT_FEATURE(journal,
 531                                            JBD2_FEATURE_COMPAT_CHECKSUM) &&
 532                                    !info->end_transaction) {
 533                                        if (calc_chksums(journal, bh,
 534                                                        &next_log_block,
 535                                                        &crc32_sum)) {
 536                                                put_bh(bh);
 537                                                break;
 538                                        }
 539                                        put_bh(bh);
 540                                        continue;
 541                                }
 542                                next_log_block += count_tags(journal, bh);
 543                                wrap(journal, next_log_block);
 544                                put_bh(bh);
 545                                continue;
 546                        }
 547
 548                        /* A descriptor block: we can now write all of
 549                         * the data blocks.  Yay, useful work is finally
 550                         * getting done here! */
 551
 552                        tagp = &bh->b_data[sizeof(journal_header_t)];
 553                        while ((tagp - bh->b_data + tag_bytes)
 554                               <= journal->j_blocksize - descr_csum_size) {
 555                                unsigned long io_block;
 556
 557                                tag = (journal_block_tag_t *) tagp;
 558                                flags = be16_to_cpu(tag->t_flags);
 559
 560                                io_block = next_log_block++;
 561                                wrap(journal, next_log_block);
 562                                err = jread(&obh, journal, io_block);
 563                                if (err) {
 564                                        /* Recover what we can, but
 565                                         * report failure at the end. */
 566                                        success = err;
 567                                        printk(KERN_ERR
 568                                                "JBD2: IO error %d recovering "
 569                                                "block %ld in log\n",
 570                                                err, io_block);
 571                                } else {
 572                                        unsigned long long blocknr;
 573
 574                                        J_ASSERT(obh != NULL);
 575                                        blocknr = read_tag_block(tag_bytes,
 576                                                                 tag);
 577
 578                                        /* If the block has been
 579                                         * revoked, then we're all done
 580                                         * here. */
 581                                        if (jbd2_journal_test_revoke
 582                                            (journal, blocknr,
 583                                             next_commit_ID)) {
 584                                                brelse(obh);
 585                                                ++info->nr_revoke_hits;
 586                                                goto skip_write;
 587                                        }
 588
 589                                        /* Look for block corruption */
 590                                        if (!jbd2_block_tag_csum_verify(
 591                                                journal, tag, obh->b_data,
 592                                                be32_to_cpu(tmp->h_sequence))) {
 593                                                brelse(obh);
 594                                                success = -EIO;
 595                                                printk(KERN_ERR "JBD: Invalid "
 596                                                       "checksum recovering "
 597                                                       "block %llu in log\n",
 598                                                       blocknr);
 599                                                continue;
 600                                        }
 601
 602                                        /* Find a buffer for the new
 603                                         * data being restored */
 604                                        nbh = __getblk(journal->j_fs_dev,
 605                                                        blocknr,
 606                                                        journal->j_blocksize);
 607                                        if (nbh == NULL) {
 608                                                printk(KERN_ERR
 609                                                       "JBD2: Out of memory "
 610                                                       "during recovery.\n");
 611                                                err = -ENOMEM;
 612                                                brelse(bh);
 613                                                brelse(obh);
 614                                                goto failed;
 615                                        }
 616
 617                                        lock_buffer(nbh);
 618                                        memcpy(nbh->b_data, obh->b_data,
 619                                                        journal->j_blocksize);
 620                                        if (flags & JBD2_FLAG_ESCAPE) {
 621                                                *((__be32 *)nbh->b_data) =
 622                                                cpu_to_be32(JBD2_MAGIC_NUMBER);
 623                                        }
 624
 625                                        BUFFER_TRACE(nbh, "marking dirty");
 626                                        set_buffer_uptodate(nbh);
 627                                        mark_buffer_dirty(nbh);
 628                                        BUFFER_TRACE(nbh, "marking uptodate");
 629                                        ++info->nr_replays;
 630                                        /* ll_rw_block(WRITE, 1, &nbh); */
 631                                        unlock_buffer(nbh);
 632                                        brelse(obh);
 633                                        brelse(nbh);
 634                                }
 635
 636                        skip_write:
 637                                tagp += tag_bytes;
 638                                if (!(flags & JBD2_FLAG_SAME_UUID))
 639                                        tagp += 16;
 640
 641                                if (flags & JBD2_FLAG_LAST_TAG)
 642                                        break;
 643                        }
 644
 645                        brelse(bh);
 646                        continue;
 647
 648                case JBD2_COMMIT_BLOCK:
 649                        /*     How to differentiate between interrupted commit
 650                         *               and journal corruption ?
 651                         *
 652                         * {nth transaction}
 653                         *        Checksum Verification Failed
 654                         *                       |
 655                         *               ____________________
 656                         *              |                    |
 657                         *      async_commit             sync_commit
 658                         *              |                    |
 659                         *              | GO TO NEXT    "Journal Corruption"
 660                         *              | TRANSACTION
 661                         *              |
 662                         * {(n+1)th transanction}
 663                         *              |
 664                         *       _______|______________
 665                         *      |                     |
 666                         * Commit block found   Commit block not found
 667                         *      |                     |
 668                         * "Journal Corruption"       |
 669                         *               _____________|_________
 670                         *              |                       |
 671                         *      nth trans corrupt       OR   nth trans
 672                         *      and (n+1)th interrupted     interrupted
 673                         *      before commit block
 674                         *      could reach the disk.
 675                         *      (Cannot find the difference in above
 676                         *       mentioned conditions. Hence assume
 677                         *       "Interrupted Commit".)
 678                         */
 679
 680                        /* Found an expected commit block: if checksums
 681                         * are present verify them in PASS_SCAN; else not
 682                         * much to do other than move on to the next sequence
 683                         * number. */
 684                        if (pass == PASS_SCAN &&
 685                            JBD2_HAS_COMPAT_FEATURE(journal,
 686                                    JBD2_FEATURE_COMPAT_CHECKSUM)) {
 687                                int chksum_err, chksum_seen;
 688                                struct commit_header *cbh =
 689                                        (struct commit_header *)bh->b_data;
 690                                unsigned found_chksum =
 691                                        be32_to_cpu(cbh->h_chksum[0]);
 692
 693                                chksum_err = chksum_seen = 0;
 694
 695                                if (info->end_transaction) {
 696                                        journal->j_failed_commit =
 697                                                info->end_transaction;
 698                                        brelse(bh);
 699                                        break;
 700                                }
 701
 702                                if (crc32_sum == found_chksum &&
 703                                    cbh->h_chksum_type == JBD2_CRC32_CHKSUM &&
 704                                    cbh->h_chksum_size ==
 705                                                JBD2_CRC32_CHKSUM_SIZE)
 706                                       chksum_seen = 1;
 707                                else if (!(cbh->h_chksum_type == 0 &&
 708                                             cbh->h_chksum_size == 0 &&
 709                                             found_chksum == 0 &&
 710                                             !chksum_seen))
 711                                /*
 712                                 * If fs is mounted using an old kernel and then
 713                                 * kernel with journal_chksum is used then we
 714                                 * get a situation where the journal flag has
 715                                 * checksum flag set but checksums are not
 716                                 * present i.e chksum = 0, in the individual
 717                                 * commit blocks.
 718                                 * Hence to avoid checksum failures, in this
 719                                 * situation, this extra check is added.
 720                                 */
 721                                                chksum_err = 1;
 722
 723                                if (chksum_err) {
 724                                        info->end_transaction = next_commit_ID;
 725
 726                                        if (!JBD2_HAS_INCOMPAT_FEATURE(journal,
 727                                           JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)){
 728                                                journal->j_failed_commit =
 729                                                        next_commit_ID;
 730                                                brelse(bh);
 731                                                break;
 732                                        }
 733                                }
 734                                crc32_sum = ~0;
 735                        }
 736                        if (pass == PASS_SCAN &&
 737                            !jbd2_commit_block_csum_verify(journal,
 738                                                           bh->b_data)) {
 739                                info->end_transaction = next_commit_ID;
 740
 741                                if (!JBD2_HAS_INCOMPAT_FEATURE(journal,
 742                                     JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
 743                                        journal->j_failed_commit =
 744                                                next_commit_ID;
 745                                        brelse(bh);
 746                                        break;
 747                                }
 748                        }
 749                        brelse(bh);
 750                        next_commit_ID++;
 751                        continue;
 752
 753                case JBD2_REVOKE_BLOCK:
 754                        /* If we aren't in the REVOKE pass, then we can
 755                         * just skip over this block. */
 756                        if (pass != PASS_REVOKE) {
 757                                brelse(bh);
 758                                continue;
 759                        }
 760
 761                        err = scan_revoke_records(journal, bh,
 762                                                  next_commit_ID, info);
 763                        brelse(bh);
 764                        if (err)
 765                                goto failed;
 766                        continue;
 767
 768                default:
 769                        jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
 770                                  blocktype);
 771                        brelse(bh);
 772                        goto done;
 773                }
 774        }
 775
 776 done:
 777        /*
 778         * We broke out of the log scan loop: either we came to the
 779         * known end of the log or we found an unexpected block in the
 780         * log.  If the latter happened, then we know that the "current"
 781         * transaction marks the end of the valid log.
 782         */
 783
 784        if (pass == PASS_SCAN) {
 785                if (!info->end_transaction)
 786                        info->end_transaction = next_commit_ID;
 787        } else {
 788                /* It's really bad news if different passes end up at
 789                 * different places (but possible due to IO errors). */
 790                if (info->end_transaction != next_commit_ID) {
 791                        printk(KERN_ERR "JBD2: recovery pass %d ended at "
 792                                "transaction %u, expected %u\n",
 793                                pass, next_commit_ID, info->end_transaction);
 794                        if (!success)
 795                                success = -EIO;
 796                }
 797        }
 798
 799        return success;
 800
 801 failed:
 802        return err;
 803}
 804
 805static int jbd2_revoke_block_csum_verify(journal_t *j,
 806                                         void *buf)
 807{
 808        struct jbd2_journal_revoke_tail *tail;
 809        __u32 provided, calculated;
 810
 811        if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 812                return 1;
 813
 814        tail = (struct jbd2_journal_revoke_tail *)(buf + j->j_blocksize -
 815                        sizeof(struct jbd2_journal_revoke_tail));
 816        provided = tail->r_checksum;
 817        tail->r_checksum = 0;
 818        calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 819        tail->r_checksum = provided;
 820
 821        provided = be32_to_cpu(provided);
 822        return provided == calculated;
 823}
 824
 825/* Scan a revoke record, marking all blocks mentioned as revoked. */
 826
 827static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
 828                               tid_t sequence, struct recovery_info *info)
 829{
 830        jbd2_journal_revoke_header_t *header;
 831        int offset, max;
 832        int record_len = 4;
 833
 834        header = (jbd2_journal_revoke_header_t *) bh->b_data;
 835        offset = sizeof(jbd2_journal_revoke_header_t);
 836        max = be32_to_cpu(header->r_count);
 837
 838        if (!jbd2_revoke_block_csum_verify(journal, header))
 839                return -EINVAL;
 840
 841        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
 842                record_len = 8;
 843
 844        while (offset + record_len <= max) {
 845                unsigned long long blocknr;
 846                int err;
 847
 848                if (record_len == 4)
 849                        blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
 850                else
 851                        blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
 852                offset += record_len;
 853                err = jbd2_journal_set_revoke(journal, blocknr, sequence);
 854                if (err)
 855                        return err;
 856                ++info->nr_revokes;
 857        }
 858        return 0;
 859}
 860
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