linux/fs/jbd2/recovery.c
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   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * linux/fs/jbd2/recovery.c
   4 *
   5 * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
   6 *
   7 * Copyright 1999-2000 Red Hat Software --- All Rights Reserved
   8 *
   9 * Journal recovery routines for the generic filesystem journaling code;
  10 * part of the ext2fs journaling system.
  11 */
  12
  13#ifndef __KERNEL__
  14#include "jfs_user.h"
  15#else
  16#include <linux/time.h>
  17#include <linux/fs.h>
  18#include <linux/jbd2.h>
  19#include <linux/errno.h>
  20#include <linux/crc32.h>
  21#include <linux/blkdev.h>
  22#endif
  23
  24/*
  25 * Maintain information about the progress of the recovery job, so that
  26 * the different passes can carry information between them.
  27 */
  28struct recovery_info
  29{
  30        tid_t           start_transaction;
  31        tid_t           end_transaction;
  32
  33        int             nr_replays;
  34        int             nr_revokes;
  35        int             nr_revoke_hits;
  36};
  37
  38static int do_one_pass(journal_t *journal,
  39                                struct recovery_info *info, enum passtype pass);
  40static int scan_revoke_records(journal_t *, struct buffer_head *,
  41                                tid_t, struct recovery_info *);
  42
  43#ifdef __KERNEL__
  44
  45/* Release readahead buffers after use */
  46static void journal_brelse_array(struct buffer_head *b[], int n)
  47{
  48        while (--n >= 0)
  49                brelse (b[n]);
  50}
  51
  52
  53/*
  54 * When reading from the journal, we are going through the block device
  55 * layer directly and so there is no readahead being done for us.  We
  56 * need to implement any readahead ourselves if we want it to happen at
  57 * all.  Recovery is basically one long sequential read, so make sure we
  58 * do the IO in reasonably large chunks.
  59 *
  60 * This is not so critical that we need to be enormously clever about
  61 * the readahead size, though.  128K is a purely arbitrary, good-enough
  62 * fixed value.
  63 */
  64
  65#define MAXBUF 8
  66static int do_readahead(journal_t *journal, unsigned int start)
  67{
  68        int err;
  69        unsigned int max, nbufs, next;
  70        unsigned long long blocknr;
  71        struct buffer_head *bh;
  72
  73        struct buffer_head * bufs[MAXBUF];
  74
  75        /* Do up to 128K of readahead */
  76        max = start + (128 * 1024 / journal->j_blocksize);
  77        if (max > journal->j_total_len)
  78                max = journal->j_total_len;
  79
  80        /* Do the readahead itself.  We'll submit MAXBUF buffer_heads at
  81         * a time to the block device IO layer. */
  82
  83        nbufs = 0;
  84
  85        for (next = start; next < max; next++) {
  86                err = jbd2_journal_bmap(journal, next, &blocknr);
  87
  88                if (err) {
  89                        printk(KERN_ERR "JBD2: bad block at offset %u\n",
  90                                next);
  91                        goto failed;
  92                }
  93
  94                bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
  95                if (!bh) {
  96                        err = -ENOMEM;
  97                        goto failed;
  98                }
  99
 100                if (!buffer_uptodate(bh) && !buffer_locked(bh)) {
 101                        bufs[nbufs++] = bh;
 102                        if (nbufs == MAXBUF) {
 103                                ll_rw_block(REQ_OP_READ, 0, nbufs, bufs);
 104                                journal_brelse_array(bufs, nbufs);
 105                                nbufs = 0;
 106                        }
 107                } else
 108                        brelse(bh);
 109        }
 110
 111        if (nbufs)
 112                ll_rw_block(REQ_OP_READ, 0, nbufs, bufs);
 113        err = 0;
 114
 115failed:
 116        if (nbufs)
 117                journal_brelse_array(bufs, nbufs);
 118        return err;
 119}
 120
 121#endif /* __KERNEL__ */
 122
 123
 124/*
 125 * Read a block from the journal
 126 */
 127
 128static int jread(struct buffer_head **bhp, journal_t *journal,
 129                 unsigned int offset)
 130{
 131        int err;
 132        unsigned long long blocknr;
 133        struct buffer_head *bh;
 134
 135        *bhp = NULL;
 136
 137        if (offset >= journal->j_total_len) {
 138                printk(KERN_ERR "JBD2: corrupted journal superblock\n");
 139                return -EFSCORRUPTED;
 140        }
 141
 142        err = jbd2_journal_bmap(journal, offset, &blocknr);
 143
 144        if (err) {
 145                printk(KERN_ERR "JBD2: bad block at offset %u\n",
 146                        offset);
 147                return err;
 148        }
 149
 150        bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
 151        if (!bh)
 152                return -ENOMEM;
 153
 154        if (!buffer_uptodate(bh)) {
 155                /* If this is a brand new buffer, start readahead.
 156                   Otherwise, we assume we are already reading it.  */
 157                if (!buffer_req(bh))
 158                        do_readahead(journal, offset);
 159                wait_on_buffer(bh);
 160        }
 161
 162        if (!buffer_uptodate(bh)) {
 163                printk(KERN_ERR "JBD2: Failed to read block at offset %u\n",
 164                        offset);
 165                brelse(bh);
 166                return -EIO;
 167        }
 168
 169        *bhp = bh;
 170        return 0;
 171}
 172
 173static int jbd2_descriptor_block_csum_verify(journal_t *j, void *buf)
 174{
 175        struct jbd2_journal_block_tail *tail;
 176        __be32 provided;
 177        __u32 calculated;
 178
 179        if (!jbd2_journal_has_csum_v2or3(j))
 180                return 1;
 181
 182        tail = (struct jbd2_journal_block_tail *)(buf + j->j_blocksize -
 183                        sizeof(struct jbd2_journal_block_tail));
 184        provided = tail->t_checksum;
 185        tail->t_checksum = 0;
 186        calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 187        tail->t_checksum = provided;
 188
 189        return provided == cpu_to_be32(calculated);
 190}
 191
 192/*
 193 * Count the number of in-use tags in a journal descriptor block.
 194 */
 195
 196static int count_tags(journal_t *journal, struct buffer_head *bh)
 197{
 198        char *                  tagp;
 199        journal_block_tag_t *   tag;
 200        int                     nr = 0, size = journal->j_blocksize;
 201        int                     tag_bytes = journal_tag_bytes(journal);
 202
 203        if (jbd2_journal_has_csum_v2or3(journal))
 204                size -= sizeof(struct jbd2_journal_block_tail);
 205
 206        tagp = &bh->b_data[sizeof(journal_header_t)];
 207
 208        while ((tagp - bh->b_data + tag_bytes) <= size) {
 209                tag = (journal_block_tag_t *) tagp;
 210
 211                nr++;
 212                tagp += tag_bytes;
 213                if (!(tag->t_flags & cpu_to_be16(JBD2_FLAG_SAME_UUID)))
 214                        tagp += 16;
 215
 216                if (tag->t_flags & cpu_to_be16(JBD2_FLAG_LAST_TAG))
 217                        break;
 218        }
 219
 220        return nr;
 221}
 222
 223
 224/* Make sure we wrap around the log correctly! */
 225#define wrap(journal, var)                                              \
 226do {                                                                    \
 227        unsigned long _wrap_last =                                      \
 228                jbd2_has_feature_fast_commit(journal) ?                 \
 229                        (journal)->j_fc_last : (journal)->j_last;       \
 230                                                                        \
 231        if (var >= _wrap_last)                                          \
 232                var -= (_wrap_last - (journal)->j_first);               \
 233} while (0)
 234
 235static int fc_do_one_pass(journal_t *journal,
 236                          struct recovery_info *info, enum passtype pass)
 237{
 238        unsigned int expected_commit_id = info->end_transaction;
 239        unsigned long next_fc_block;
 240        struct buffer_head *bh;
 241        int err = 0;
 242
 243        next_fc_block = journal->j_fc_first;
 244        if (!journal->j_fc_replay_callback)
 245                return 0;
 246
 247        while (next_fc_block <= journal->j_fc_last) {
 248                jbd_debug(3, "Fast commit replay: next block %ld\n",
 249                          next_fc_block);
 250                err = jread(&bh, journal, next_fc_block);
 251                if (err) {
 252                        jbd_debug(3, "Fast commit replay: read error\n");
 253                        break;
 254                }
 255
 256                err = journal->j_fc_replay_callback(journal, bh, pass,
 257                                        next_fc_block - journal->j_fc_first,
 258                                        expected_commit_id);
 259                next_fc_block++;
 260                if (err < 0 || err == JBD2_FC_REPLAY_STOP)
 261                        break;
 262                err = 0;
 263        }
 264
 265        if (err)
 266                jbd_debug(3, "Fast commit replay failed, err = %d\n", err);
 267
 268        return err;
 269}
 270
 271/**
 272 * jbd2_journal_recover - recovers a on-disk journal
 273 * @journal: the journal to recover
 274 *
 275 * The primary function for recovering the log contents when mounting a
 276 * journaled device.
 277 *
 278 * Recovery is done in three passes.  In the first pass, we look for the
 279 * end of the log.  In the second, we assemble the list of revoke
 280 * blocks.  In the third and final pass, we replay any un-revoked blocks
 281 * in the log.
 282 */
 283int jbd2_journal_recover(journal_t *journal)
 284{
 285        int                     err, err2;
 286        journal_superblock_t *  sb;
 287
 288        struct recovery_info    info;
 289
 290        memset(&info, 0, sizeof(info));
 291        sb = journal->j_superblock;
 292
 293        /*
 294         * The journal superblock's s_start field (the current log head)
 295         * is always zero if, and only if, the journal was cleanly
 296         * unmounted.
 297         */
 298
 299        if (!sb->s_start) {
 300                jbd_debug(1, "No recovery required, last transaction %d\n",
 301                          be32_to_cpu(sb->s_sequence));
 302                journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
 303                return 0;
 304        }
 305
 306        err = do_one_pass(journal, &info, PASS_SCAN);
 307        if (!err)
 308                err = do_one_pass(journal, &info, PASS_REVOKE);
 309        if (!err)
 310                err = do_one_pass(journal, &info, PASS_REPLAY);
 311
 312        jbd_debug(1, "JBD2: recovery, exit status %d, "
 313                  "recovered transactions %u to %u\n",
 314                  err, info.start_transaction, info.end_transaction);
 315        jbd_debug(1, "JBD2: Replayed %d and revoked %d/%d blocks\n",
 316                  info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
 317
 318        /* Restart the log at the next transaction ID, thus invalidating
 319         * any existing commit records in the log. */
 320        journal->j_transaction_sequence = ++info.end_transaction;
 321
 322        jbd2_journal_clear_revoke(journal);
 323        err2 = sync_blockdev(journal->j_fs_dev);
 324        if (!err)
 325                err = err2;
 326        /* Make sure all replayed data is on permanent storage */
 327        if (journal->j_flags & JBD2_BARRIER) {
 328                err2 = blkdev_issue_flush(journal->j_fs_dev);
 329                if (!err)
 330                        err = err2;
 331        }
 332        return err;
 333}
 334
 335/**
 336 * jbd2_journal_skip_recovery - Start journal and wipe exiting records
 337 * @journal: journal to startup
 338 *
 339 * Locate any valid recovery information from the journal and set up the
 340 * journal structures in memory to ignore it (presumably because the
 341 * caller has evidence that it is out of date).
 342 * This function doesn't appear to be exported..
 343 *
 344 * We perform one pass over the journal to allow us to tell the user how
 345 * much recovery information is being erased, and to let us initialise
 346 * the journal transaction sequence numbers to the next unused ID.
 347 */
 348int jbd2_journal_skip_recovery(journal_t *journal)
 349{
 350        int                     err;
 351
 352        struct recovery_info    info;
 353
 354        memset (&info, 0, sizeof(info));
 355
 356        err = do_one_pass(journal, &info, PASS_SCAN);
 357
 358        if (err) {
 359                printk(KERN_ERR "JBD2: error %d scanning journal\n", err);
 360                ++journal->j_transaction_sequence;
 361        } else {
 362#ifdef CONFIG_JBD2_DEBUG
 363                int dropped = info.end_transaction - 
 364                        be32_to_cpu(journal->j_superblock->s_sequence);
 365                jbd_debug(1,
 366                          "JBD2: ignoring %d transaction%s from the journal.\n",
 367                          dropped, (dropped == 1) ? "" : "s");
 368#endif
 369                journal->j_transaction_sequence = ++info.end_transaction;
 370        }
 371
 372        journal->j_tail = 0;
 373        return err;
 374}
 375
 376static inline unsigned long long read_tag_block(journal_t *journal,
 377                                                journal_block_tag_t *tag)
 378{
 379        unsigned long long block = be32_to_cpu(tag->t_blocknr);
 380        if (jbd2_has_feature_64bit(journal))
 381                block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
 382        return block;
 383}
 384
 385/*
 386 * calc_chksums calculates the checksums for the blocks described in the
 387 * descriptor block.
 388 */
 389static int calc_chksums(journal_t *journal, struct buffer_head *bh,
 390                        unsigned long *next_log_block, __u32 *crc32_sum)
 391{
 392        int i, num_blks, err;
 393        unsigned long io_block;
 394        struct buffer_head *obh;
 395
 396        num_blks = count_tags(journal, bh);
 397        /* Calculate checksum of the descriptor block. */
 398        *crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
 399
 400        for (i = 0; i < num_blks; i++) {
 401                io_block = (*next_log_block)++;
 402                wrap(journal, *next_log_block);
 403                err = jread(&obh, journal, io_block);
 404                if (err) {
 405                        printk(KERN_ERR "JBD2: IO error %d recovering block "
 406                                "%lu in log\n", err, io_block);
 407                        return 1;
 408                } else {
 409                        *crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
 410                                     obh->b_size);
 411                }
 412                put_bh(obh);
 413        }
 414        return 0;
 415}
 416
 417static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
 418{
 419        struct commit_header *h;
 420        __be32 provided;
 421        __u32 calculated;
 422
 423        if (!jbd2_journal_has_csum_v2or3(j))
 424                return 1;
 425
 426        h = buf;
 427        provided = h->h_chksum[0];
 428        h->h_chksum[0] = 0;
 429        calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 430        h->h_chksum[0] = provided;
 431
 432        return provided == cpu_to_be32(calculated);
 433}
 434
 435static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
 436                                      void *buf, __u32 sequence)
 437{
 438        journal_block_tag3_t *tag3 = (journal_block_tag3_t *)tag;
 439        __u32 csum32;
 440        __be32 seq;
 441
 442        if (!jbd2_journal_has_csum_v2or3(j))
 443                return 1;
 444
 445        seq = cpu_to_be32(sequence);
 446        csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
 447        csum32 = jbd2_chksum(j, csum32, buf, j->j_blocksize);
 448
 449        if (jbd2_has_feature_csum3(j))
 450                return tag3->t_checksum == cpu_to_be32(csum32);
 451        else
 452                return tag->t_checksum == cpu_to_be16(csum32);
 453}
 454
 455static int do_one_pass(journal_t *journal,
 456                        struct recovery_info *info, enum passtype pass)
 457{
 458        unsigned int            first_commit_ID, next_commit_ID;
 459        unsigned long           next_log_block;
 460        int                     err, success = 0;
 461        journal_superblock_t *  sb;
 462        journal_header_t *      tmp;
 463        struct buffer_head *    bh;
 464        unsigned int            sequence;
 465        int                     blocktype;
 466        int                     tag_bytes = journal_tag_bytes(journal);
 467        __u32                   crc32_sum = ~0; /* Transactional Checksums */
 468        int                     descr_csum_size = 0;
 469        int                     block_error = 0;
 470        bool                    need_check_commit_time = false;
 471        __u64                   last_trans_commit_time = 0, commit_time;
 472
 473        /*
 474         * First thing is to establish what we expect to find in the log
 475         * (in terms of transaction IDs), and where (in terms of log
 476         * block offsets): query the superblock.
 477         */
 478
 479        sb = journal->j_superblock;
 480        next_commit_ID = be32_to_cpu(sb->s_sequence);
 481        next_log_block = be32_to_cpu(sb->s_start);
 482
 483        first_commit_ID = next_commit_ID;
 484        if (pass == PASS_SCAN)
 485                info->start_transaction = first_commit_ID;
 486
 487        jbd_debug(1, "Starting recovery pass %d\n", pass);
 488
 489        /*
 490         * Now we walk through the log, transaction by transaction,
 491         * making sure that each transaction has a commit block in the
 492         * expected place.  Each complete transaction gets replayed back
 493         * into the main filesystem.
 494         */
 495
 496        while (1) {
 497                int                     flags;
 498                char *                  tagp;
 499                journal_block_tag_t *   tag;
 500                struct buffer_head *    obh;
 501                struct buffer_head *    nbh;
 502
 503                cond_resched();
 504
 505                /* If we already know where to stop the log traversal,
 506                 * check right now that we haven't gone past the end of
 507                 * the log. */
 508
 509                if (pass != PASS_SCAN)
 510                        if (tid_geq(next_commit_ID, info->end_transaction))
 511                                break;
 512
 513                jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
 514                          next_commit_ID, next_log_block,
 515                          jbd2_has_feature_fast_commit(journal) ?
 516                          journal->j_fc_last : journal->j_last);
 517
 518                /* Skip over each chunk of the transaction looking
 519                 * either the next descriptor block or the final commit
 520                 * record. */
 521
 522                jbd_debug(3, "JBD2: checking block %ld\n", next_log_block);
 523                err = jread(&bh, journal, next_log_block);
 524                if (err)
 525                        goto failed;
 526
 527                next_log_block++;
 528                wrap(journal, next_log_block);
 529
 530                /* What kind of buffer is it?
 531                 *
 532                 * If it is a descriptor block, check that it has the
 533                 * expected sequence number.  Otherwise, we're all done
 534                 * here. */
 535
 536                tmp = (journal_header_t *)bh->b_data;
 537
 538                if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
 539                        brelse(bh);
 540                        break;
 541                }
 542
 543                blocktype = be32_to_cpu(tmp->h_blocktype);
 544                sequence = be32_to_cpu(tmp->h_sequence);
 545                jbd_debug(3, "Found magic %d, sequence %d\n",
 546                          blocktype, sequence);
 547
 548                if (sequence != next_commit_ID) {
 549                        brelse(bh);
 550                        break;
 551                }
 552
 553                /* OK, we have a valid descriptor block which matches
 554                 * all of the sequence number checks.  What are we going
 555                 * to do with it?  That depends on the pass... */
 556
 557                switch(blocktype) {
 558                case JBD2_DESCRIPTOR_BLOCK:
 559                        /* Verify checksum first */
 560                        if (jbd2_journal_has_csum_v2or3(journal))
 561                                descr_csum_size =
 562                                        sizeof(struct jbd2_journal_block_tail);
 563                        if (descr_csum_size > 0 &&
 564                            !jbd2_descriptor_block_csum_verify(journal,
 565                                                               bh->b_data)) {
 566                                /*
 567                                 * PASS_SCAN can see stale blocks due to lazy
 568                                 * journal init. Don't error out on those yet.
 569                                 */
 570                                if (pass != PASS_SCAN) {
 571                                        pr_err("JBD2: Invalid checksum recovering block %lu in log\n",
 572                                               next_log_block);
 573                                        err = -EFSBADCRC;
 574                                        brelse(bh);
 575                                        goto failed;
 576                                }
 577                                need_check_commit_time = true;
 578                                jbd_debug(1,
 579                                        "invalid descriptor block found in %lu\n",
 580                                        next_log_block);
 581                        }
 582
 583                        /* If it is a valid descriptor block, replay it
 584                         * in pass REPLAY; if journal_checksums enabled, then
 585                         * calculate checksums in PASS_SCAN, otherwise,
 586                         * just skip over the blocks it describes. */
 587                        if (pass != PASS_REPLAY) {
 588                                if (pass == PASS_SCAN &&
 589                                    jbd2_has_feature_checksum(journal) &&
 590                                    !need_check_commit_time &&
 591                                    !info->end_transaction) {
 592                                        if (calc_chksums(journal, bh,
 593                                                        &next_log_block,
 594                                                        &crc32_sum)) {
 595                                                put_bh(bh);
 596                                                break;
 597                                        }
 598                                        put_bh(bh);
 599                                        continue;
 600                                }
 601                                next_log_block += count_tags(journal, bh);
 602                                wrap(journal, next_log_block);
 603                                put_bh(bh);
 604                                continue;
 605                        }
 606
 607                        /* A descriptor block: we can now write all of
 608                         * the data blocks.  Yay, useful work is finally
 609                         * getting done here! */
 610
 611                        tagp = &bh->b_data[sizeof(journal_header_t)];
 612                        while ((tagp - bh->b_data + tag_bytes)
 613                               <= journal->j_blocksize - descr_csum_size) {
 614                                unsigned long io_block;
 615
 616                                tag = (journal_block_tag_t *) tagp;
 617                                flags = be16_to_cpu(tag->t_flags);
 618
 619                                io_block = next_log_block++;
 620                                wrap(journal, next_log_block);
 621                                err = jread(&obh, journal, io_block);
 622                                if (err) {
 623                                        /* Recover what we can, but
 624                                         * report failure at the end. */
 625                                        success = err;
 626                                        printk(KERN_ERR
 627                                                "JBD2: IO error %d recovering "
 628                                                "block %ld in log\n",
 629                                                err, io_block);
 630                                } else {
 631                                        unsigned long long blocknr;
 632
 633                                        J_ASSERT(obh != NULL);
 634                                        blocknr = read_tag_block(journal,
 635                                                                 tag);
 636
 637                                        /* If the block has been
 638                                         * revoked, then we're all done
 639                                         * here. */
 640                                        if (jbd2_journal_test_revoke
 641                                            (journal, blocknr,
 642                                             next_commit_ID)) {
 643                                                brelse(obh);
 644                                                ++info->nr_revoke_hits;
 645                                                goto skip_write;
 646                                        }
 647
 648                                        /* Look for block corruption */
 649                                        if (!jbd2_block_tag_csum_verify(
 650                                                journal, tag, obh->b_data,
 651                                                be32_to_cpu(tmp->h_sequence))) {
 652                                                brelse(obh);
 653                                                success = -EFSBADCRC;
 654                                                printk(KERN_ERR "JBD2: Invalid "
 655                                                       "checksum recovering "
 656                                                       "data block %llu in "
 657                                                       "log\n", blocknr);
 658                                                block_error = 1;
 659                                                goto skip_write;
 660                                        }
 661
 662                                        /* Find a buffer for the new
 663                                         * data being restored */
 664                                        nbh = __getblk(journal->j_fs_dev,
 665                                                        blocknr,
 666                                                        journal->j_blocksize);
 667                                        if (nbh == NULL) {
 668                                                printk(KERN_ERR
 669                                                       "JBD2: Out of memory "
 670                                                       "during recovery.\n");
 671                                                err = -ENOMEM;
 672                                                brelse(bh);
 673                                                brelse(obh);
 674                                                goto failed;
 675                                        }
 676
 677                                        lock_buffer(nbh);
 678                                        memcpy(nbh->b_data, obh->b_data,
 679                                                        journal->j_blocksize);
 680                                        if (flags & JBD2_FLAG_ESCAPE) {
 681                                                *((__be32 *)nbh->b_data) =
 682                                                cpu_to_be32(JBD2_MAGIC_NUMBER);
 683                                        }
 684
 685                                        BUFFER_TRACE(nbh, "marking dirty");
 686                                        set_buffer_uptodate(nbh);
 687                                        mark_buffer_dirty(nbh);
 688                                        BUFFER_TRACE(nbh, "marking uptodate");
 689                                        ++info->nr_replays;
 690                                        /* ll_rw_block(WRITE, 1, &nbh); */
 691                                        unlock_buffer(nbh);
 692                                        brelse(obh);
 693                                        brelse(nbh);
 694                                }
 695
 696                        skip_write:
 697                                tagp += tag_bytes;
 698                                if (!(flags & JBD2_FLAG_SAME_UUID))
 699                                        tagp += 16;
 700
 701                                if (flags & JBD2_FLAG_LAST_TAG)
 702                                        break;
 703                        }
 704
 705                        brelse(bh);
 706                        continue;
 707
 708                case JBD2_COMMIT_BLOCK:
 709                        /*     How to differentiate between interrupted commit
 710                         *               and journal corruption ?
 711                         *
 712                         * {nth transaction}
 713                         *        Checksum Verification Failed
 714                         *                       |
 715                         *               ____________________
 716                         *              |                    |
 717                         *      async_commit             sync_commit
 718                         *              |                    |
 719                         *              | GO TO NEXT    "Journal Corruption"
 720                         *              | TRANSACTION
 721                         *              |
 722                         * {(n+1)th transanction}
 723                         *              |
 724                         *       _______|______________
 725                         *      |                     |
 726                         * Commit block found   Commit block not found
 727                         *      |                     |
 728                         * "Journal Corruption"       |
 729                         *               _____________|_________
 730                         *              |                       |
 731                         *      nth trans corrupt       OR   nth trans
 732                         *      and (n+1)th interrupted     interrupted
 733                         *      before commit block
 734                         *      could reach the disk.
 735                         *      (Cannot find the difference in above
 736                         *       mentioned conditions. Hence assume
 737                         *       "Interrupted Commit".)
 738                         */
 739                        commit_time = be64_to_cpu(
 740                                ((struct commit_header *)bh->b_data)->h_commit_sec);
 741                        /*
 742                         * If need_check_commit_time is set, it means we are in
 743                         * PASS_SCAN and csum verify failed before. If
 744                         * commit_time is increasing, it's the same journal,
 745                         * otherwise it is stale journal block, just end this
 746                         * recovery.
 747                         */
 748                        if (need_check_commit_time) {
 749                                if (commit_time >= last_trans_commit_time) {
 750                                        pr_err("JBD2: Invalid checksum found in transaction %u\n",
 751                                               next_commit_ID);
 752                                        err = -EFSBADCRC;
 753                                        brelse(bh);
 754                                        goto failed;
 755                                }
 756                        ignore_crc_mismatch:
 757                                /*
 758                                 * It likely does not belong to same journal,
 759                                 * just end this recovery with success.
 760                                 */
 761                                jbd_debug(1, "JBD2: Invalid checksum ignored in transaction %u, likely stale data\n",
 762                                          next_commit_ID);
 763                                err = 0;
 764                                brelse(bh);
 765                                goto done;
 766                        }
 767
 768                        /*
 769                         * Found an expected commit block: if checksums
 770                         * are present, verify them in PASS_SCAN; else not
 771                         * much to do other than move on to the next sequence
 772                         * number.
 773                         */
 774                        if (pass == PASS_SCAN &&
 775                            jbd2_has_feature_checksum(journal)) {
 776                                struct commit_header *cbh =
 777                                        (struct commit_header *)bh->b_data;
 778                                unsigned found_chksum =
 779                                        be32_to_cpu(cbh->h_chksum[0]);
 780
 781                                if (info->end_transaction) {
 782                                        journal->j_failed_commit =
 783                                                info->end_transaction;
 784                                        brelse(bh);
 785                                        break;
 786                                }
 787
 788                                /* Neither checksum match nor unused? */
 789                                if (!((crc32_sum == found_chksum &&
 790                                       cbh->h_chksum_type ==
 791                                                JBD2_CRC32_CHKSUM &&
 792                                       cbh->h_chksum_size ==
 793                                                JBD2_CRC32_CHKSUM_SIZE) ||
 794                                      (cbh->h_chksum_type == 0 &&
 795                                       cbh->h_chksum_size == 0 &&
 796                                       found_chksum == 0)))
 797                                        goto chksum_error;
 798
 799                                crc32_sum = ~0;
 800                        }
 801                        if (pass == PASS_SCAN &&
 802                            !jbd2_commit_block_csum_verify(journal,
 803                                                           bh->b_data)) {
 804                        chksum_error:
 805                                if (commit_time < last_trans_commit_time)
 806                                        goto ignore_crc_mismatch;
 807                                info->end_transaction = next_commit_ID;
 808
 809                                if (!jbd2_has_feature_async_commit(journal)) {
 810                                        journal->j_failed_commit =
 811                                                next_commit_ID;
 812                                        brelse(bh);
 813                                        break;
 814                                }
 815                        }
 816                        if (pass == PASS_SCAN)
 817                                last_trans_commit_time = commit_time;
 818                        brelse(bh);
 819                        next_commit_ID++;
 820                        continue;
 821
 822                case JBD2_REVOKE_BLOCK:
 823                        /*
 824                         * Check revoke block crc in pass_scan, if csum verify
 825                         * failed, check commit block time later.
 826                         */
 827                        if (pass == PASS_SCAN &&
 828                            !jbd2_descriptor_block_csum_verify(journal,
 829                                                               bh->b_data)) {
 830                                jbd_debug(1, "JBD2: invalid revoke block found in %lu\n",
 831                                          next_log_block);
 832                                need_check_commit_time = true;
 833                        }
 834                        /* If we aren't in the REVOKE pass, then we can
 835                         * just skip over this block. */
 836                        if (pass != PASS_REVOKE) {
 837                                brelse(bh);
 838                                continue;
 839                        }
 840
 841                        err = scan_revoke_records(journal, bh,
 842                                                  next_commit_ID, info);
 843                        brelse(bh);
 844                        if (err)
 845                                goto failed;
 846                        continue;
 847
 848                default:
 849                        jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
 850                                  blocktype);
 851                        brelse(bh);
 852                        goto done;
 853                }
 854        }
 855
 856 done:
 857        /*
 858         * We broke out of the log scan loop: either we came to the
 859         * known end of the log or we found an unexpected block in the
 860         * log.  If the latter happened, then we know that the "current"
 861         * transaction marks the end of the valid log.
 862         */
 863
 864        if (pass == PASS_SCAN) {
 865                if (!info->end_transaction)
 866                        info->end_transaction = next_commit_ID;
 867        } else {
 868                /* It's really bad news if different passes end up at
 869                 * different places (but possible due to IO errors). */
 870                if (info->end_transaction != next_commit_ID) {
 871                        printk(KERN_ERR "JBD2: recovery pass %d ended at "
 872                                "transaction %u, expected %u\n",
 873                                pass, next_commit_ID, info->end_transaction);
 874                        if (!success)
 875                                success = -EIO;
 876                }
 877        }
 878
 879        if (jbd2_has_feature_fast_commit(journal) &&  pass != PASS_REVOKE) {
 880                err = fc_do_one_pass(journal, info, pass);
 881                if (err)
 882                        success = err;
 883        }
 884
 885        if (block_error && success == 0)
 886                success = -EIO;
 887        return success;
 888
 889 failed:
 890        return err;
 891}
 892
 893/* Scan a revoke record, marking all blocks mentioned as revoked. */
 894
 895static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
 896                               tid_t sequence, struct recovery_info *info)
 897{
 898        jbd2_journal_revoke_header_t *header;
 899        int offset, max;
 900        int csum_size = 0;
 901        __u32 rcount;
 902        int record_len = 4;
 903
 904        header = (jbd2_journal_revoke_header_t *) bh->b_data;
 905        offset = sizeof(jbd2_journal_revoke_header_t);
 906        rcount = be32_to_cpu(header->r_count);
 907
 908        if (jbd2_journal_has_csum_v2or3(journal))
 909                csum_size = sizeof(struct jbd2_journal_block_tail);
 910        if (rcount > journal->j_blocksize - csum_size)
 911                return -EINVAL;
 912        max = rcount;
 913
 914        if (jbd2_has_feature_64bit(journal))
 915                record_len = 8;
 916
 917        while (offset + record_len <= max) {
 918                unsigned long long blocknr;
 919                int err;
 920
 921                if (record_len == 4)
 922                        blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
 923                else
 924                        blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
 925                offset += record_len;
 926                err = jbd2_journal_set_revoke(journal, blocknr, sequence);
 927                if (err)
 928                        return err;
 929                ++info->nr_revokes;
 930        }
 931        return 0;
 932}
 933