jbd2/recovery.c

   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  */
  28 struct 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
  38 static int do_one_pass(journal_t *journal,
  39                                 struct recovery_info *info, enum passtype pass);
  40 static 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 */
  46 static 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
  66 static 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                                 bh_readahead_batch(nbufs, bufs, 0);
 104                                 journal_brelse_array(bufs, nbufs);
 105                                 nbufs = 0;
 106                         }
 107                 } else
 108                         brelse(bh);
 109         }
 110
 111         if (nbufs)
 112                 bh_readahead_batch(nbufs, bufs, 0);
 113         err = 0;
 114
 115 failed:
 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
 128 static 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                 /*
 156                  * If this is a brand new buffer, start readahead.
 157                  * Otherwise, we assume we are already reading it.
 158                  */
 159                 bool need_readahead = !buffer_req(bh);
 160
 161                 bh_read_nowait(bh, 0);
 162                 if (need_readahead)
 163                         do_readahead(journal, offset);
 164                 wait_on_buffer(bh);
 165         }
 166
 167         if (!buffer_uptodate(bh)) {
 168                 printk(KERN_ERR "JBD2: Failed to read block at offset %u\n",
 169                         offset);
 170                 brelse(bh);
 171                 return -EIO;
 172         }
 173
 174         *bhp = bh;
 175         return 0;
 176 }
 177
 178 static int jbd2_descriptor_block_csum_verify(journal_t *j, void *buf)
 179 {
 180         struct jbd2_journal_block_tail *tail;
 181         __be32 provided;
 182         __u32 calculated;
 183
 184         if (!jbd2_journal_has_csum_v2or3(j))
 185                 return 1;
 186
 187         tail = (struct jbd2_journal_block_tail *)((char *)buf +
 188                 j->j_blocksize - sizeof(struct jbd2_journal_block_tail));
 189         provided = tail->t_checksum;
 190         tail->t_checksum = 0;
 191         calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 192         tail->t_checksum = provided;
 193
 194         return provided == cpu_to_be32(calculated);
 195 }
 196
 197 /*
 198  * Count the number of in-use tags in a journal descriptor block.
 199  */
 200
 201 static 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_journal_has_csum_v2or3(journal))
 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                 memcpy(&tag, tagp, sizeof(tag));
 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)                                              \
 231 do {                                                                    \
 232         if (var >= (journal)->j_last)                                   \
 233                 var -= ((journal)->j_last - (journal)->j_first);        \
 234 } while (0)
 235
 236 static int fc_do_one_pass(journal_t *journal,
 237                           struct recovery_info *info, enum passtype pass)
 238 {
 239         unsigned int expected_commit_id = info->end_transaction;
 240         unsigned long next_fc_block;
 241         struct buffer_head *bh;
 242         int err = 0;
 243
 244         next_fc_block = journal->j_fc_first;
 245         if (!journal->j_fc_replay_callback)
 246                 return 0;
 247
 248         while (next_fc_block <= journal->j_fc_last) {
 249                 jbd2_debug(3, "Fast commit replay: next block %ld\n",
 250                           next_fc_block);
 251                 err = jread(&bh, journal, next_fc_block);
 252                 if (err) {
 253                         jbd2_debug(3, "Fast commit replay: read error\n");
 254                         break;
 255                 }
 256
 257                 err = journal->j_fc_replay_callback(journal, bh, pass,
 258                                         next_fc_block - journal->j_fc_first,
 259                                         expected_commit_id);
 260                 brelse(bh);
 261                 next_fc_block++;
 262                 if (err < 0 || err == JBD2_FC_REPLAY_STOP)
 263                         break;
 264                 err = 0;
 265         }
 266
 267         if (err)
 268                 jbd2_debug(3, "Fast commit replay failed, err = %d\n", err);
 269
 270         return err;
 271 }
 272
 273 /**
 274  * jbd2_journal_recover - recovers a on-disk journal
 275  * @journal: the journal to recover
 276  *
 277  * The primary function for recovering the log contents when mounting a
 278  * journaled device.
 279  *
 280  * Recovery is done in three passes.  In the first pass, we look for the
 281  * end of the log.  In the second, we assemble the list of revoke
 282  * blocks.  In the third and final pass, we replay any un-revoked blocks
 283  * in the log.
 284  */
 285 int jbd2_journal_recover(journal_t *journal)
 286 {
 287         int                     err, err2;
 288         journal_superblock_t *  sb;
 289
 290         struct recovery_info    info;
 291         errseq_t                wb_err;
 292         struct address_space    *mapping;
 293
 294         memset(&info, 0, sizeof(info));
 295         sb = journal->j_superblock;
 296
 297         /*
 298          * The journal superblock's s_start field (the current log head)
 299          * is always zero if, and only if, the journal was cleanly
 300          * unmounted.
 301          */
 302
 303         if (!sb->s_start) {
 304                 jbd2_debug(1, "No recovery required, last transaction %d\n",
 305                           be32_to_cpu(sb->s_sequence));
 306                 journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
 307                 return 0;
 308         }
 309
 310         wb_err = 0;
 311         mapping = journal->j_fs_dev->bd_inode->i_mapping;
 312         errseq_check_and_advance(&mapping->wb_err, &wb_err);
 313         err = do_one_pass(journal, &info, PASS_SCAN);
 314         if (!err)
 315                 err = do_one_pass(journal, &info, PASS_REVOKE);
 316         if (!err)
 317                 err = do_one_pass(journal, &info, PASS_REPLAY);
 318
 319         jbd2_debug(1, "JBD2: recovery, exit status %d, "
 320                   "recovered transactions %u to %u\n",
 321                   err, info.start_transaction, info.end_transaction);
 322         jbd2_debug(1, "JBD2: Replayed %d and revoked %d/%d blocks\n",
 323                   info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
 324
 325         /* Restart the log at the next transaction ID, thus invalidating
 326          * any existing commit records in the log. */
 327         journal->j_transaction_sequence = ++info.end_transaction;
 328
 329         jbd2_journal_clear_revoke(journal);
 330         err2 = sync_blockdev(journal->j_fs_dev);
 331         if (!err)
 332                 err = err2;
 333         err2 = errseq_check_and_advance(&mapping->wb_err, &wb_err);
 334         if (!err)
 335                 err = err2;
 336         /* Make sure all replayed data is on permanent storage */
 337         if (journal->j_flags & JBD2_BARRIER) {
 338                 err2 = blkdev_issue_flush(journal->j_fs_dev);
 339                 if (!err)
 340                         err = err2;
 341         }
 342         return err;
 343 }
 344
 345 /**
 346  * jbd2_journal_skip_recovery - Start journal and wipe exiting records
 347  * @journal: journal to startup
 348  *
 349  * Locate any valid recovery information from the journal and set up the
 350  * journal structures in memory to ignore it (presumably because the
 351  * caller has evidence that it is out of date).
 352  * This function doesn't appear to be exported..
 353  *
 354  * We perform one pass over the journal to allow us to tell the user how
 355  * much recovery information is being erased, and to let us initialise
 356  * the journal transaction sequence numbers to the next unused ID.
 357  */
 358 int jbd2_journal_skip_recovery(journal_t *journal)
 359 {
 360         int                     err;
 361
 362         struct recovery_info    info;
 363
 364         memset (&info, 0, sizeof(info));
 365
 366         err = do_one_pass(journal, &info, PASS_SCAN);
 367
 368         if (err) {
 369                 printk(KERN_ERR "JBD2: error %d scanning journal\n", err);
 370                 ++journal->j_transaction_sequence;
 371         } else {
 372 #ifdef CONFIG_JBD2_DEBUG
 373                 int dropped = info.end_transaction -
 374                         be32_to_cpu(journal->j_superblock->s_sequence);
 375                 jbd2_debug(1,
 376                           "JBD2: ignoring %d transaction%s from the journal.\n",
 377                           dropped, (dropped == 1) ? "" : "s");
 378 #endif
 379                 journal->j_transaction_sequence = ++info.end_transaction;
 380         }
 381
 382         journal->j_tail = 0;
 383         return err;
 384 }
 385
 386 static inline unsigned long long read_tag_block(journal_t *journal,
 387                                                 journal_block_tag_t *tag)
 388 {
 389         unsigned long long block = be32_to_cpu(tag->t_blocknr);
 390         if (jbd2_has_feature_64bit(journal))
 391                 block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
 392         return block;
 393 }
 394
 395 /*
 396  * calc_chksums calculates the checksums for the blocks described in the
 397  * descriptor block.
 398  */
 399 static int calc_chksums(journal_t *journal, struct buffer_head *bh,
 400                         unsigned long *next_log_block, __u32 *crc32_sum)
 401 {
 402         int i, num_blks, err;
 403         unsigned long io_block;
 404         struct buffer_head *obh;
 405
 406         num_blks = count_tags(journal, bh);
 407         /* Calculate checksum of the descriptor block. */
 408         *crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
 409
 410         for (i = 0; i < num_blks; i++) {
 411                 io_block = (*next_log_block)++;
 412                 wrap(journal, *next_log_block);
 413                 err = jread(&obh, journal, io_block);
 414                 if (err) {
 415                         printk(KERN_ERR "JBD2: IO error %d recovering block "
 416                                 "%lu in log\n", err, io_block);
 417                         return 1;
 418                 } else {
 419                         *crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
 420                                      obh->b_size);
 421                 }
 422                 put_bh(obh);
 423         }
 424         return 0;
 425 }
 426
 427 static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
 428 {
 429         struct commit_header *h;
 430         __be32 provided;
 431         __u32 calculated;
 432
 433         if (!jbd2_journal_has_csum_v2or3(j))
 434                 return 1;
 435
 436         h = buf;
 437         provided = h->h_chksum[0];
 438         h->h_chksum[0] = 0;
 439         calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 440         h->h_chksum[0] = provided;
 441
 442         return provided == cpu_to_be32(calculated);
 443 }
 444
 445 static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
 446                                       journal_block_tag3_t *tag3,
 447                                       void *buf, __u32 sequence)
 448 {
 449         __u32 csum32;
 450         __be32 seq;
 451
 452         if (!jbd2_journal_has_csum_v2or3(j))
 453                 return 1;
 454
 455         seq = cpu_to_be32(sequence);
 456         csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
 457         csum32 = jbd2_chksum(j, csum32, buf, j->j_blocksize);
 458
 459         if (jbd2_has_feature_csum3(j))
 460                 return tag3->t_checksum == cpu_to_be32(csum32);
 461         else
 462                 return tag->t_checksum == cpu_to_be16(csum32);
 463 }
 464
 465 static int do_one_pass(journal_t *journal,
 466                         struct recovery_info *info, enum passtype pass)
 467 {
 468         unsigned int            first_commit_ID, next_commit_ID;
 469         unsigned long           next_log_block;
 470         int                     err, success = 0;
 471         journal_superblock_t *  sb;
 472         journal_header_t *      tmp;
 473         struct buffer_head *    bh;
 474         unsigned int            sequence;
 475         int                     blocktype;
 476         int                     tag_bytes = journal_tag_bytes(journal);
 477         __u32                   crc32_sum = ~0; /* Transactional Checksums */
 478         int                     descr_csum_size = 0;
 479         int                     block_error = 0;
 480         bool                    need_check_commit_time = false;
 481         __u64                   last_trans_commit_time = 0, commit_time;
 482
 483         /*
 484          * First thing is to establish what we expect to find in the log
 485          * (in terms of transaction IDs), and where (in terms of log
 486          * block offsets): query the superblock.
 487          */
 488
 489         sb = journal->j_superblock;
 490         next_commit_ID = be32_to_cpu(sb->s_sequence);
 491         next_log_block = be32_to_cpu(sb->s_start);
 492
 493         first_commit_ID = next_commit_ID;
 494         if (pass == PASS_SCAN)
 495                 info->start_transaction = first_commit_ID;
 496
 497         jbd2_debug(1, "Starting recovery pass %d\n", pass);
 498
 499         /*
 500          * Now we walk through the log, transaction by transaction,
 501          * making sure that each transaction has a commit block in the
 502          * expected place.  Each complete transaction gets replayed back
 503          * into the main filesystem.
 504          */
 505
 506         while (1) {
 507                 int                     flags;
 508                 char *                  tagp;
 509                 journal_block_tag_t     tag;
 510                 struct buffer_head *    obh;
 511                 struct buffer_head *    nbh;
 512
 513                 cond_resched();
 514
 515                 /* If we already know where to stop the log traversal,
 516                  * check right now that we haven't gone past the end of
 517                  * the log. */
 518
 519                 if (pass != PASS_SCAN)
 520                         if (tid_geq(next_commit_ID, info->end_transaction))
 521                                 break;
 522
 523                 jbd2_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
 524                           next_commit_ID, next_log_block, journal->j_last);
 525
 526                 /* Skip over each chunk of the transaction looking
 527                  * either the next descriptor block or the final commit
 528                  * record. */
 529
 530                 jbd2_debug(3, "JBD2: checking block %ld\n", next_log_block);
 531                 err = jread(&bh, journal, next_log_block);
 532                 if (err)
 533                         goto failed;
 534
 535                 next_log_block++;
 536                 wrap(journal, next_log_block);
 537
 538                 /* What kind of buffer is it?
 539                  *
 540                  * If it is a descriptor block, check that it has the
 541                  * expected sequence number.  Otherwise, we're all done
 542                  * here. */
 543
 544                 tmp = (journal_header_t *)bh->b_data;
 545
 546                 if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
 547                         brelse(bh);
 548                         break;
 549                 }
 550
 551                 blocktype = be32_to_cpu(tmp->h_blocktype);
 552                 sequence = be32_to_cpu(tmp->h_sequence);
 553                 jbd2_debug(3, "Found magic %d, sequence %d\n",
 554                           blocktype, sequence);
 555
 556                 if (sequence != next_commit_ID) {
 557                         brelse(bh);
 558                         break;
 559                 }
 560
 561                 /* OK, we have a valid descriptor block which matches
 562                  * all of the sequence number checks.  What are we going
 563                  * to do with it?  That depends on the pass... */
 564
 565                 switch(blocktype) {
 566                 case JBD2_DESCRIPTOR_BLOCK:
 567                         /* Verify checksum first */
 568                         if (jbd2_journal_has_csum_v2or3(journal))
 569                                 descr_csum_size =
 570                                         sizeof(struct jbd2_journal_block_tail);
 571                         if (descr_csum_size > 0 &&
 572                             !jbd2_descriptor_block_csum_verify(journal,
 573                                                                bh->b_data)) {
 574                                 /*
 575                                  * PASS_SCAN can see stale blocks due to lazy
 576                                  * journal init. Don't error out on those yet.
 577                                  */
 578                                 if (pass != PASS_SCAN) {
 579                                         pr_err("JBD2: Invalid checksum recovering block %lu in log\n",
 580                                                next_log_block);
 581                                         err = -EFSBADCRC;
 582                                         brelse(bh);
 583                                         goto failed;
 584                                 }
 585                                 need_check_commit_time = true;
 586                                 jbd2_debug(1,
 587                                         "invalid descriptor block found in %lu\n",
 588                                         next_log_block);
 589                         }
 590
 591                         /* If it is a valid descriptor block, replay it
 592                          * in pass REPLAY; if journal_checksums enabled, then
 593                          * calculate checksums in PASS_SCAN, otherwise,
 594                          * just skip over the blocks it describes. */
 595                         if (pass != PASS_REPLAY) {
 596                                 if (pass == PASS_SCAN &&
 597                                     jbd2_has_feature_checksum(journal) &&
 598                                     !need_check_commit_time &&
 599                                     !info->end_transaction) {
 600                                         if (calc_chksums(journal, bh,
 601                                                         &next_log_block,
 602                                                         &crc32_sum)) {
 603                                                 put_bh(bh);
 604                                                 break;
 605                                         }
 606                                         put_bh(bh);
 607                                         continue;
 608                                 }
 609                                 next_log_block += count_tags(journal, bh);
 610                                 wrap(journal, next_log_block);
 611                                 put_bh(bh);
 612                                 continue;
 613                         }
 614
 615                         /* A descriptor block: we can now write all of
 616                          * the data blocks.  Yay, useful work is finally
 617                          * getting done here! */
 618
 619                         tagp = &bh->b_data[sizeof(journal_header_t)];
 620                         while ((tagp - bh->b_data + tag_bytes)
 621                                <= journal->j_blocksize - descr_csum_size) {
 622                                 unsigned long io_block;
 623
 624                                 memcpy(&tag, tagp, sizeof(tag));
 625                                 flags = be16_to_cpu(tag.t_flags);
 626
 627                                 io_block = next_log_block++;
 628                                 wrap(journal, next_log_block);
 629                                 err = jread(&obh, journal, io_block);
 630                                 if (err) {
 631                                         /* Recover what we can, but
 632                                          * report failure at the end. */
 633                                         success = err;
 634                                         printk(KERN_ERR
 635                                                 "JBD2: IO error %d recovering "
 636                                                 "block %ld in log\n",
 637                                                 err, io_block);
 638                                 } else {
 639                                         unsigned long long blocknr;
 640
 641                                         J_ASSERT(obh != NULL);
 642                                         blocknr = read_tag_block(journal,
 643                                                                  &tag);
 644
 645                                         /* If the block has been
 646                                          * revoked, then we're all done
 647                                          * here. */
 648                                         if (jbd2_journal_test_revoke
 649                                             (journal, blocknr,
 650                                              next_commit_ID)) {
 651                                                 brelse(obh);
 652                                                 ++info->nr_revoke_hits;
 653                                                 goto skip_write;
 654                                         }
 655
 656                                         /* Look for block corruption */
 657                                         if (!jbd2_block_tag_csum_verify(
 658                         journal, &tag, (journal_block_tag3_t *)tagp,
 659                         obh->b_data, be32_to_cpu(tmp->h_sequence))) {
 660                                                 brelse(obh);
 661                                                 success = -EFSBADCRC;
 662                                                 printk(KERN_ERR "JBD2: Invalid "
 663                                                        "checksum recovering "
 664                                                        "data block %llu in "
 665                                                        "log\n", blocknr);
 666                                                 block_error = 1;
 667                                                 goto skip_write;
 668                                         }
 669
 670                                         /* Find a buffer for the new
 671                                          * data being restored */
 672                                         nbh = __getblk(journal->j_fs_dev,
 673                                                         blocknr,
 674                                                         journal->j_blocksize);
 675                                         if (nbh == NULL) {
 676                                                 printk(KERN_ERR
 677                                                        "JBD2: Out of memory "
 678                                                        "during recovery.\n");
 679                                                 err = -ENOMEM;
 680                                                 brelse(bh);
 681                                                 brelse(obh);
 682                                                 goto failed;
 683                                         }
 684
 685                                         lock_buffer(nbh);
 686                                         memcpy(nbh->b_data, obh->b_data,
 687                                                         journal->j_blocksize);
 688                                         if (flags & JBD2_FLAG_ESCAPE) {
 689                                                 *((__be32 *)nbh->b_data) =
 690                                                 cpu_to_be32(JBD2_MAGIC_NUMBER);
 691                                         }
 692
 693                                         BUFFER_TRACE(nbh, "marking dirty");
 694                                         set_buffer_uptodate(nbh);
 695                                         mark_buffer_dirty(nbh);
 696                                         BUFFER_TRACE(nbh, "marking uptodate");
 697                                         ++info->nr_replays;
 698                                         unlock_buffer(nbh);
 699                                         brelse(obh);
 700                                         brelse(nbh);
 701                                 }
 702
 703                         skip_write:
 704                                 tagp += tag_bytes;
 705                                 if (!(flags & JBD2_FLAG_SAME_UUID))
 706                                         tagp += 16;
 707
 708                                 if (flags & JBD2_FLAG_LAST_TAG)
 709                                         break;
 710                         }
 711
 712                         brelse(bh);
 713                         continue;
 714
 715                 case JBD2_COMMIT_BLOCK:
 716                         /*     How to differentiate between interrupted commit
 717                          *               and journal corruption ?
 718                          *
 719                          * {nth transaction}
 720                          *        Checksum Verification Failed
 721                          *                       |
 722                          *               ____________________
 723                          *              |                    |
 724                          *      async_commit             sync_commit
 725                          *              |                    |
 726                          *              | GO TO NEXT    "Journal Corruption"
 727                          *              | TRANSACTION
 728                          *              |
 729                          * {(n+1)th transanction}
 730                          *              |
 731                          *       _______|______________
 732                          *      |                     |
 733                          * Commit block found   Commit block not found
 734                          *      |                     |
 735                          * "Journal Corruption"       |
 736                          *               _____________|_________
 737                          *              |                       |
 738                          *      nth trans corrupt       OR   nth trans
 739                          *      and (n+1)th interrupted     interrupted
 740                          *      before commit block
 741                          *      could reach the disk.
 742                          *      (Cannot find the difference in above
 743                          *       mentioned conditions. Hence assume
 744                          *       "Interrupted Commit".)
 745                          */
 746                         commit_time = be64_to_cpu(
 747                                 ((struct commit_header *)bh->b_data)->h_commit_sec);
 748                         /*
 749                          * If need_check_commit_time is set, it means we are in
 750                          * PASS_SCAN and csum verify failed before. If
 751                          * commit_time is increasing, it's the same journal,
 752                          * otherwise it is stale journal block, just end this
 753                          * recovery.
 754                          */
 755                         if (need_check_commit_time) {
 756                                 if (commit_time >= last_trans_commit_time) {
 757                                         pr_err("JBD2: Invalid checksum found in transaction %u\n",
 758                                                next_commit_ID);
 759                                         err = -EFSBADCRC;
 760                                         brelse(bh);
 761                                         goto failed;
 762                                 }
 763                         ignore_crc_mismatch:
 764                                 /*
 765                                  * It likely does not belong to same journal,
 766                                  * just end this recovery with success.
 767                                  */
 768                                 jbd2_debug(1, "JBD2: Invalid checksum ignored in transaction %u, likely stale data\n",
 769                                           next_commit_ID);
 770                                 brelse(bh);
 771                                 goto done;
 772                         }
 773
 774                         /*
 775                          * Found an expected commit block: if checksums
 776                          * are present, verify them in PASS_SCAN; else not
 777                          * much to do other than move on to the next sequence
 778                          * number.
 779                          */
 780                         if (pass == PASS_SCAN &&
 781                             jbd2_has_feature_checksum(journal)) {
 782                                 struct commit_header *cbh =
 783                                         (struct commit_header *)bh->b_data;
 784                                 unsigned found_chksum =
 785                                         be32_to_cpu(cbh->h_chksum[0]);
 786
 787                                 if (info->end_transaction) {
 788                                         journal->j_failed_commit =
 789                                                 info->end_transaction;
 790                                         brelse(bh);
 791                                         break;
 792                                 }
 793
 794                                 /* Neither checksum match nor unused? */
 795                                 if (!((crc32_sum == found_chksum &&
 796                                        cbh->h_chksum_type ==
 797                                                 JBD2_CRC32_CHKSUM &&
 798                                        cbh->h_chksum_size ==
 799                                                 JBD2_CRC32_CHKSUM_SIZE) ||
 800                                       (cbh->h_chksum_type == 0 &&
 801                                        cbh->h_chksum_size == 0 &&
 802                                        found_chksum == 0)))
 803                                         goto chksum_error;
 804
 805                                 crc32_sum = ~0;
 806                         }
 807                         if (pass == PASS_SCAN &&
 808                             !jbd2_commit_block_csum_verify(journal,
 809                                                            bh->b_data)) {
 810                         chksum_error:
 811                                 if (commit_time < last_trans_commit_time)
 812                                         goto ignore_crc_mismatch;
 813                                 info->end_transaction = next_commit_ID;
 814
 815                                 if (!jbd2_has_feature_async_commit(journal)) {
 816                                         journal->j_failed_commit =
 817                                                 next_commit_ID;
 818                                         brelse(bh);
 819                                         break;
 820                                 }
 821                         }
 822                         if (pass == PASS_SCAN)
 823                                 last_trans_commit_time = commit_time;
 824                         brelse(bh);
 825                         next_commit_ID++;
 826                         continue;
 827
 828                 case JBD2_REVOKE_BLOCK:
 829                         /*
 830                          * Check revoke block crc in pass_scan, if csum verify
 831                          * failed, check commit block time later.
 832                          */
 833                         if (pass == PASS_SCAN &&
 834                             !jbd2_descriptor_block_csum_verify(journal,
 835                                                                bh->b_data)) {
 836                                 jbd2_debug(1, "JBD2: invalid revoke block found in %lu\n",
 837                                           next_log_block);
 838                                 need_check_commit_time = true;
 839                         }
 840                         /* If we aren't in the REVOKE pass, then we can
 841                          * just skip over this block. */
 842                         if (pass != PASS_REVOKE) {
 843                                 brelse(bh);
 844                                 continue;
 845                         }
 846
 847                         err = scan_revoke_records(journal, bh,
 848                                                   next_commit_ID, info);
 849                         brelse(bh);
 850                         if (err)
 851                                 goto failed;
 852                         continue;
 853
 854                 default:
 855                         jbd2_debug(3, "Unrecognised magic %d, end of scan.\n",
 856                                   blocktype);
 857                         brelse(bh);
 858                         goto done;
 859                 }
 860         }
 861
 862  done:
 863         /*
 864          * We broke out of the log scan loop: either we came to the
 865          * known end of the log or we found an unexpected block in the
 866          * log.  If the latter happened, then we know that the "current"
 867          * transaction marks the end of the valid log.
 868          */
 869
 870         if (pass == PASS_SCAN) {
 871                 if (!info->end_transaction)
 872                         info->end_transaction = next_commit_ID;
 873         } else {
 874                 /* It's really bad news if different passes end up at
 875                  * different places (but possible due to IO errors). */
 876                 if (info->end_transaction != next_commit_ID) {
 877                         printk(KERN_ERR "JBD2: recovery pass %d ended at "
 878                                 "transaction %u, expected %u\n",
 879                                 pass, next_commit_ID, info->end_transaction);
 880                         if (!success)
 881                                 success = -EIO;
 882                 }
 883         }
 884
 885         if (jbd2_has_feature_fast_commit(journal) &&  pass != PASS_REVOKE) {
 886                 err = fc_do_one_pass(journal, info, pass);
 887                 if (err)
 888                         success = err;
 889         }
 890
 891         if (block_error && success == 0)
 892                 success = -EIO;
 893         return success;
 894
 895  failed:
 896         return err;
 897 }
 898
 899 /* Scan a revoke record, marking all blocks mentioned as revoked. */
 900
 901 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
 902                                tid_t sequence, struct recovery_info *info)
 903 {
 904         jbd2_journal_revoke_header_t *header;
 905         int offset, max;
 906         unsigned csum_size = 0;
 907         __u32 rcount;
 908         int record_len = 4;
 909
 910         header = (jbd2_journal_revoke_header_t *) bh->b_data;
 911         offset = sizeof(jbd2_journal_revoke_header_t);
 912         rcount = be32_to_cpu(header->r_count);
 913
 914         if (jbd2_journal_has_csum_v2or3(journal))
 915                 csum_size = sizeof(struct jbd2_journal_block_tail);
 916         if (rcount > journal->j_blocksize - csum_size)
 917                 return -EINVAL;
 918         max = rcount;
 919
 920         if (jbd2_has_feature_64bit(journal))
 921                 record_len = 8;
 922
 923         while (offset + record_len <= max) {
 924                 unsigned long long blocknr;
 925                 int err;
 926
 927                 if (record_len == 4)
 928                         blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
 929                 else
 930                         blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
 931                 offset += record_len;
 932                 err = jbd2_journal_set_revoke(journal, blocknr, sequence);
 933                 if (err)
 934                         return err;
 935                 ++info->nr_revokes;
 936         }
 937         return 0;
 938 }