fs/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                                 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
 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                 /* 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
 173 static 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 *)((char *)buf +
 183                 j->j_blocksize - 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
 196 static 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                 memcpy(&tag, tagp, sizeof(tag));
 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)                                              \
 226 do {                                                                    \
 227         if (var >= (journal)->j_last)                                   \
 228                 var -= ((journal)->j_last - (journal)->j_first);        \
 229 } while (0)
 230
 231 static int fc_do_one_pass(journal_t *journal,
 232                           struct recovery_info *info, enum passtype pass)
 233 {
 234         unsigned int expected_commit_id = info->end_transaction;
 235         unsigned long next_fc_block;
 236         struct buffer_head *bh;
 237         int err = 0;
 238
 239         next_fc_block = journal->j_fc_first;
 240         if (!journal->j_fc_replay_callback)
 241                 return 0;
 242
 243         while (next_fc_block <= journal->j_fc_last) {
 244                 jbd2_debug(3, "Fast commit replay: next block %ld\n",
 245                           next_fc_block);
 246                 err = jread(&bh, journal, next_fc_block);
 247                 if (err) {
 248                         jbd2_debug(3, "Fast commit replay: read error\n");
 249                         break;
 250                 }
 251
 252                 err = journal->j_fc_replay_callback(journal, bh, pass,
 253                                         next_fc_block - journal->j_fc_first,
 254                                         expected_commit_id);
 255                 brelse(bh);
 256                 next_fc_block++;
 257                 if (err < 0 || err == JBD2_FC_REPLAY_STOP)
 258                         break;
 259                 err = 0;
 260         }
 261
 262         if (err)
 263                 jbd2_debug(3, "Fast commit replay failed, err = %d\n", err);
 264
 265         return err;
 266 }
 267
 268 /**
 269  * jbd2_journal_recover - recovers a on-disk journal
 270  * @journal: the journal to recover
 271  *
 272  * The primary function for recovering the log contents when mounting a
 273  * journaled device.
 274  *
 275  * Recovery is done in three passes.  In the first pass, we look for the
 276  * end of the log.  In the second, we assemble the list of revoke
 277  * blocks.  In the third and final pass, we replay any un-revoked blocks
 278  * in the log.
 279  */
 280 int jbd2_journal_recover(journal_t *journal)
 281 {
 282         int                     err, err2;
 283         journal_superblock_t *  sb;
 284
 285         struct recovery_info    info;
 286
 287         memset(&info, 0, sizeof(info));
 288         sb = journal->j_superblock;
 289
 290         /*
 291          * The journal superblock's s_start field (the current log head)
 292          * is always zero if, and only if, the journal was cleanly
 293          * unmounted.
 294          */
 295
 296         if (!sb->s_start) {
 297                 jbd2_debug(1, "No recovery required, last transaction %d\n",
 298                           be32_to_cpu(sb->s_sequence));
 299                 journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
 300                 return 0;
 301         }
 302
 303         err = do_one_pass(journal, &info, PASS_SCAN);
 304         if (!err)
 305                 err = do_one_pass(journal, &info, PASS_REVOKE);
 306         if (!err)
 307                 err = do_one_pass(journal, &info, PASS_REPLAY);
 308
 309         jbd2_debug(1, "JBD2: recovery, exit status %d, "
 310                   "recovered transactions %u to %u\n",
 311                   err, info.start_transaction, info.end_transaction);
 312         jbd2_debug(1, "JBD2: Replayed %d and revoked %d/%d blocks\n",
 313                   info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
 314
 315         /* Restart the log at the next transaction ID, thus invalidating
 316          * any existing commit records in the log. */
 317         journal->j_transaction_sequence = ++info.end_transaction;
 318
 319         jbd2_journal_clear_revoke(journal);
 320         err2 = sync_blockdev(journal->j_fs_dev);
 321         if (!err)
 322                 err = err2;
 323         /* Make sure all replayed data is on permanent storage */
 324         if (journal->j_flags & JBD2_BARRIER) {
 325                 err2 = blkdev_issue_flush(journal->j_fs_dev);
 326                 if (!err)
 327                         err = err2;
 328         }
 329         return err;
 330 }
 331
 332 /**
 333  * jbd2_journal_skip_recovery - Start journal and wipe exiting records
 334  * @journal: journal to startup
 335  *
 336  * Locate any valid recovery information from the journal and set up the
 337  * journal structures in memory to ignore it (presumably because the
 338  * caller has evidence that it is out of date).
 339  * This function doesn't appear to be exported..
 340  *
 341  * We perform one pass over the journal to allow us to tell the user how
 342  * much recovery information is being erased, and to let us initialise
 343  * the journal transaction sequence numbers to the next unused ID.
 344  */
 345 int jbd2_journal_skip_recovery(journal_t *journal)
 346 {
 347         int                     err;
 348
 349         struct recovery_info    info;
 350
 351         memset (&info, 0, sizeof(info));
 352
 353         err = do_one_pass(journal, &info, PASS_SCAN);
 354
 355         if (err) {
 356                 printk(KERN_ERR "JBD2: error %d scanning journal\n", err);
 357                 ++journal->j_transaction_sequence;
 358         } else {
 359 #ifdef CONFIG_JBD2_DEBUG
 360                 int dropped = info.end_transaction -
 361                         be32_to_cpu(journal->j_superblock->s_sequence);
 362                 jbd2_debug(1,
 363                           "JBD2: ignoring %d transaction%s from the journal.\n",
 364                           dropped, (dropped == 1) ? "" : "s");
 365 #endif
 366                 journal->j_transaction_sequence = ++info.end_transaction;
 367         }
 368
 369         journal->j_tail = 0;
 370         return err;
 371 }
 372
 373 static inline unsigned long long read_tag_block(journal_t *journal,
 374                                                 journal_block_tag_t *tag)
 375 {
 376         unsigned long long block = be32_to_cpu(tag->t_blocknr);
 377         if (jbd2_has_feature_64bit(journal))
 378                 block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
 379         return block;
 380 }
 381
 382 /*
 383  * calc_chksums calculates the checksums for the blocks described in the
 384  * descriptor block.
 385  */
 386 static int calc_chksums(journal_t *journal, struct buffer_head *bh,
 387                         unsigned long *next_log_block, __u32 *crc32_sum)
 388 {
 389         int i, num_blks, err;
 390         unsigned long io_block;
 391         struct buffer_head *obh;
 392
 393         num_blks = count_tags(journal, bh);
 394         /* Calculate checksum of the descriptor block. */
 395         *crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
 396
 397         for (i = 0; i < num_blks; i++) {
 398                 io_block = (*next_log_block)++;
 399                 wrap(journal, *next_log_block);
 400                 err = jread(&obh, journal, io_block);
 401                 if (err) {
 402                         printk(KERN_ERR "JBD2: IO error %d recovering block "
 403                                 "%lu in log\n", err, io_block);
 404                         return 1;
 405                 } else {
 406                         *crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
 407                                      obh->b_size);
 408                 }
 409                 put_bh(obh);
 410         }
 411         return 0;
 412 }
 413
 414 static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
 415 {
 416         struct commit_header *h;
 417         __be32 provided;
 418         __u32 calculated;
 419
 420         if (!jbd2_journal_has_csum_v2or3(j))
 421                 return 1;
 422
 423         h = buf;
 424         provided = h->h_chksum[0];
 425         h->h_chksum[0] = 0;
 426         calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 427         h->h_chksum[0] = provided;
 428
 429         return provided == cpu_to_be32(calculated);
 430 }
 431
 432 static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
 433                                       journal_block_tag3_t *tag3,
 434                                       void *buf, __u32 sequence)
 435 {
 436         __u32 csum32;
 437         __be32 seq;
 438
 439         if (!jbd2_journal_has_csum_v2or3(j))
 440                 return 1;
 441
 442         seq = cpu_to_be32(sequence);
 443         csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
 444         csum32 = jbd2_chksum(j, csum32, buf, j->j_blocksize);
 445
 446         if (jbd2_has_feature_csum3(j))
 447                 return tag3->t_checksum == cpu_to_be32(csum32);
 448         else
 449                 return tag->t_checksum == cpu_to_be16(csum32);
 450 }
 451
 452 static int do_one_pass(journal_t *journal,
 453                         struct recovery_info *info, enum passtype pass)
 454 {
 455         unsigned int            first_commit_ID, next_commit_ID;
 456         unsigned long           next_log_block;
 457         int                     err, success = 0;
 458         journal_superblock_t *  sb;
 459         journal_header_t *      tmp;
 460         struct buffer_head *    bh;
 461         unsigned int            sequence;
 462         int                     blocktype;
 463         int                     tag_bytes = journal_tag_bytes(journal);
 464         __u32                   crc32_sum = ~0; /* Transactional Checksums */
 465         int                     descr_csum_size = 0;
 466         int                     block_error = 0;
 467         bool                    need_check_commit_time = false;
 468         __u64                   last_trans_commit_time = 0, commit_time;
 469
 470         /*
 471          * First thing is to establish what we expect to find in the log
 472          * (in terms of transaction IDs), and where (in terms of log
 473          * block offsets): query the superblock.
 474          */
 475
 476         sb = journal->j_superblock;
 477         next_commit_ID = be32_to_cpu(sb->s_sequence);
 478         next_log_block = be32_to_cpu(sb->s_start);
 479
 480         first_commit_ID = next_commit_ID;
 481         if (pass == PASS_SCAN)
 482                 info->start_transaction = first_commit_ID;
 483
 484         jbd2_debug(1, "Starting recovery pass %d\n", pass);
 485
 486         /*
 487          * Now we walk through the log, transaction by transaction,
 488          * making sure that each transaction has a commit block in the
 489          * expected place.  Each complete transaction gets replayed back
 490          * into the main filesystem.
 491          */
 492
 493         while (1) {
 494                 int                     flags;
 495                 char *                  tagp;
 496                 journal_block_tag_t     tag;
 497                 struct buffer_head *    obh;
 498                 struct buffer_head *    nbh;
 499
 500                 cond_resched();
 501
 502                 /* If we already know where to stop the log traversal,
 503                  * check right now that we haven't gone past the end of
 504                  * the log. */
 505
 506                 if (pass != PASS_SCAN)
 507                         if (tid_geq(next_commit_ID, info->end_transaction))
 508                                 break;
 509
 510                 jbd2_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
 511                           next_commit_ID, next_log_block, journal->j_last);
 512
 513                 /* Skip over each chunk of the transaction looking
 514                  * either the next descriptor block or the final commit
 515                  * record. */
 516
 517                 jbd2_debug(3, "JBD2: checking block %ld\n", next_log_block);
 518                 err = jread(&bh, journal, next_log_block);
 519                 if (err)
 520                         goto failed;
 521
 522                 next_log_block++;
 523                 wrap(journal, next_log_block);
 524
 525                 /* What kind of buffer is it?
 526                  *
 527                  * If it is a descriptor block, check that it has the
 528                  * expected sequence number.  Otherwise, we're all done
 529                  * here. */
 530
 531                 tmp = (journal_header_t *)bh->b_data;
 532
 533                 if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
 534                         brelse(bh);
 535                         break;
 536                 }
 537
 538                 blocktype = be32_to_cpu(tmp->h_blocktype);
 539                 sequence = be32_to_cpu(tmp->h_sequence);
 540                 jbd2_debug(3, "Found magic %d, sequence %d\n",
 541                           blocktype, sequence);
 542
 543                 if (sequence != next_commit_ID) {
 544                         brelse(bh);
 545                         break;
 546                 }
 547
 548                 /* OK, we have a valid descriptor block which matches
 549                  * all of the sequence number checks.  What are we going
 550                  * to do with it?  That depends on the pass... */
 551
 552                 switch(blocktype) {
 553                 case JBD2_DESCRIPTOR_BLOCK:
 554                         /* Verify checksum first */
 555                         if (jbd2_journal_has_csum_v2or3(journal))
 556                                 descr_csum_size =
 557                                         sizeof(struct jbd2_journal_block_tail);
 558                         if (descr_csum_size > 0 &&
 559                             !jbd2_descriptor_block_csum_verify(journal,
 560                                                                bh->b_data)) {
 561                                 /*
 562                                  * PASS_SCAN can see stale blocks due to lazy
 563                                  * journal init. Don't error out on those yet.
 564                                  */
 565                                 if (pass != PASS_SCAN) {
 566                                         pr_err("JBD2: Invalid checksum recovering block %lu in log\n",
 567                                                next_log_block);
 568                                         err = -EFSBADCRC;
 569                                         brelse(bh);
 570                                         goto failed;
 571                                 }
 572                                 need_check_commit_time = true;
 573                                 jbd2_debug(1,
 574                                         "invalid descriptor block found in %lu\n",
 575                                         next_log_block);
 576                         }
 577
 578                         /* If it is a valid descriptor block, replay it
 579                          * in pass REPLAY; if journal_checksums enabled, then
 580                          * calculate checksums in PASS_SCAN, otherwise,
 581                          * just skip over the blocks it describes. */
 582                         if (pass != PASS_REPLAY) {
 583                                 if (pass == PASS_SCAN &&
 584                                     jbd2_has_feature_checksum(journal) &&
 585                                     !need_check_commit_time &&
 586                                     !info->end_transaction) {
 587                                         if (calc_chksums(journal, bh,
 588                                                         &next_log_block,
 589                                                         &crc32_sum)) {
 590                                                 put_bh(bh);
 591                                                 break;
 592                                         }
 593                                         put_bh(bh);
 594                                         continue;
 595                                 }
 596                                 next_log_block += count_tags(journal, bh);
 597                                 wrap(journal, next_log_block);
 598                                 put_bh(bh);
 599                                 continue;
 600                         }
 601
 602                         /* A descriptor block: we can now write all of
 603                          * the data blocks.  Yay, useful work is finally
 604                          * getting done here! */
 605
 606                         tagp = &bh->b_data[sizeof(journal_header_t)];
 607                         while ((tagp - bh->b_data + tag_bytes)
 608                                <= journal->j_blocksize - descr_csum_size) {
 609                                 unsigned long io_block;
 610
 611                                 memcpy(&tag, tagp, sizeof(tag));
 612                                 flags = be16_to_cpu(tag.t_flags);
 613
 614                                 io_block = next_log_block++;
 615                                 wrap(journal, next_log_block);
 616                                 err = jread(&obh, journal, io_block);
 617                                 if (err) {
 618                                         /* Recover what we can, but
 619                                          * report failure at the end. */
 620                                         success = err;
 621                                         printk(KERN_ERR
 622                                                 "JBD2: IO error %d recovering "
 623                                                 "block %ld in log\n",
 624                                                 err, io_block);
 625                                 } else {
 626                                         unsigned long long blocknr;
 627
 628                                         J_ASSERT(obh != NULL);
 629                                         blocknr = read_tag_block(journal,
 630                                                                  &tag);
 631
 632                                         /* If the block has been
 633                                          * revoked, then we're all done
 634                                          * here. */
 635                                         if (jbd2_journal_test_revoke
 636                                             (journal, blocknr,
 637                                              next_commit_ID)) {
 638                                                 brelse(obh);
 639                                                 ++info->nr_revoke_hits;
 640                                                 goto skip_write;
 641                                         }
 642
 643                                         /* Look for block corruption */
 644                                         if (!jbd2_block_tag_csum_verify(
 645                         journal, &tag, (journal_block_tag3_t *)tagp,
 646                         obh->b_data, be32_to_cpu(tmp->h_sequence))) {
 647                                                 brelse(obh);
 648                                                 success = -EFSBADCRC;
 649                                                 printk(KERN_ERR "JBD2: Invalid "
 650                                                        "checksum recovering "
 651                                                        "data block %llu in "
 652                                                        "log\n", blocknr);
 653                                                 block_error = 1;
 654                                                 goto skip_write;
 655                                         }
 656
 657                                         /* Find a buffer for the new
 658                                          * data being restored */
 659                                         nbh = __getblk(journal->j_fs_dev,
 660                                                         blocknr,
 661                                                         journal->j_blocksize);
 662                                         if (nbh == NULL) {
 663                                                 printk(KERN_ERR
 664                                                        "JBD2: Out of memory "
 665                                                        "during recovery.\n");
 666                                                 err = -ENOMEM;
 667                                                 brelse(bh);
 668                                                 brelse(obh);
 669                                                 goto failed;
 670                                         }
 671
 672                                         lock_buffer(nbh);
 673                                         memcpy(nbh->b_data, obh->b_data,
 674                                                         journal->j_blocksize);
 675                                         if (flags & JBD2_FLAG_ESCAPE) {
 676                                                 *((__be32 *)nbh->b_data) =
 677                                                 cpu_to_be32(JBD2_MAGIC_NUMBER);
 678                                         }
 679
 680                                         BUFFER_TRACE(nbh, "marking dirty");
 681                                         set_buffer_uptodate(nbh);
 682                                         mark_buffer_dirty(nbh);
 683                                         BUFFER_TRACE(nbh, "marking uptodate");
 684                                         ++info->nr_replays;
 685                                         /* ll_rw_block(WRITE, 1, &nbh); */
 686                                         unlock_buffer(nbh);
 687                                         brelse(obh);
 688                                         brelse(nbh);
 689                                 }
 690
 691                         skip_write:
 692                                 tagp += tag_bytes;
 693                                 if (!(flags & JBD2_FLAG_SAME_UUID))
 694                                         tagp += 16;
 695
 696                                 if (flags & JBD2_FLAG_LAST_TAG)
 697                                         break;
 698                         }
 699
 700                         brelse(bh);
 701                         continue;
 702
 703                 case JBD2_COMMIT_BLOCK:
 704                         /*     How to differentiate between interrupted commit
 705                          *               and journal corruption ?
 706                          *
 707                          * {nth transaction}
 708                          *        Checksum Verification Failed
 709                          *                       |
 710                          *               ____________________
 711                          *              |                    |
 712                          *      async_commit             sync_commit
 713                          *              |                    |
 714                          *              | GO TO NEXT    "Journal Corruption"
 715                          *              | TRANSACTION
 716                          *              |
 717                          * {(n+1)th transanction}
 718                          *              |
 719                          *       _______|______________
 720                          *      |                     |
 721                          * Commit block found   Commit block not found
 722                          *      |                     |
 723                          * "Journal Corruption"       |
 724                          *               _____________|_________
 725                          *              |                       |
 726                          *      nth trans corrupt       OR   nth trans
 727                          *      and (n+1)th interrupted     interrupted
 728                          *      before commit block
 729                          *      could reach the disk.
 730                          *      (Cannot find the difference in above
 731                          *       mentioned conditions. Hence assume
 732                          *       "Interrupted Commit".)
 733                          */
 734                         commit_time = be64_to_cpu(
 735                                 ((struct commit_header *)bh->b_data)->h_commit_sec);
 736                         /*
 737                          * If need_check_commit_time is set, it means we are in
 738                          * PASS_SCAN and csum verify failed before. If
 739                          * commit_time is increasing, it's the same journal,
 740                          * otherwise it is stale journal block, just end this
 741                          * recovery.
 742                          */
 743                         if (need_check_commit_time) {
 744                                 if (commit_time >= last_trans_commit_time) {
 745                                         pr_err("JBD2: Invalid checksum found in transaction %u\n",
 746                                                next_commit_ID);
 747                                         err = -EFSBADCRC;
 748                                         brelse(bh);
 749                                         goto failed;
 750                                 }
 751                         ignore_crc_mismatch:
 752                                 /*
 753                                  * It likely does not belong to same journal,
 754                                  * just end this recovery with success.
 755                                  */
 756                                 jbd2_debug(1, "JBD2: Invalid checksum ignored in transaction %u, likely stale data\n",
 757                                           next_commit_ID);
 758                                 brelse(bh);
 759                                 goto done;
 760                         }
 761
 762                         /*
 763                          * Found an expected commit block: if checksums
 764                          * are present, verify them in PASS_SCAN; else not
 765                          * much to do other than move on to the next sequence
 766                          * number.
 767                          */
 768                         if (pass == PASS_SCAN &&
 769                             jbd2_has_feature_checksum(journal)) {
 770                                 struct commit_header *cbh =
 771                                         (struct commit_header *)bh->b_data;
 772                                 unsigned found_chksum =
 773                                         be32_to_cpu(cbh->h_chksum[0]);
 774
 775                                 if (info->end_transaction) {
 776                                         journal->j_failed_commit =
 777                                                 info->end_transaction;
 778                                         brelse(bh);
 779                                         break;
 780                                 }
 781
 782                                 /* Neither checksum match nor unused? */
 783                                 if (!((crc32_sum == found_chksum &&
 784                                        cbh->h_chksum_type ==
 785                                                 JBD2_CRC32_CHKSUM &&
 786                                        cbh->h_chksum_size ==
 787                                                 JBD2_CRC32_CHKSUM_SIZE) ||
 788                                       (cbh->h_chksum_type == 0 &&
 789                                        cbh->h_chksum_size == 0 &&
 790                                        found_chksum == 0)))
 791                                         goto chksum_error;
 792
 793                                 crc32_sum = ~0;
 794                         }
 795                         if (pass == PASS_SCAN &&
 796                             !jbd2_commit_block_csum_verify(journal,
 797                                                            bh->b_data)) {
 798                         chksum_error:
 799                                 if (commit_time < last_trans_commit_time)
 800                                         goto ignore_crc_mismatch;
 801                                 info->end_transaction = next_commit_ID;
 802
 803                                 if (!jbd2_has_feature_async_commit(journal)) {
 804                                         journal->j_failed_commit =
 805                                                 next_commit_ID;
 806                                         brelse(bh);
 807                                         break;
 808                                 }
 809                         }
 810                         if (pass == PASS_SCAN)
 811                                 last_trans_commit_time = commit_time;
 812                         brelse(bh);
 813                         next_commit_ID++;
 814                         continue;
 815
 816                 case JBD2_REVOKE_BLOCK:
 817                         /*
 818                          * Check revoke block crc in pass_scan, if csum verify
 819                          * failed, check commit block time later.
 820                          */
 821                         if (pass == PASS_SCAN &&
 822                             !jbd2_descriptor_block_csum_verify(journal,
 823                                                                bh->b_data)) {
 824                                 jbd2_debug(1, "JBD2: invalid revoke block found in %lu\n",
 825                                           next_log_block);
 826                                 need_check_commit_time = true;
 827                         }
 828                         /* If we aren't in the REVOKE pass, then we can
 829                          * just skip over this block. */
 830                         if (pass != PASS_REVOKE) {
 831                                 brelse(bh);
 832                                 continue;
 833                         }
 834
 835                         err = scan_revoke_records(journal, bh,
 836                                                   next_commit_ID, info);
 837                         brelse(bh);
 838                         if (err)
 839                                 goto failed;
 840                         continue;
 841
 842                 default:
 843                         jbd2_debug(3, "Unrecognised magic %d, end of scan.\n",
 844                                   blocktype);
 845                         brelse(bh);
 846                         goto done;
 847                 }
 848         }
 849
 850  done:
 851         /*
 852          * We broke out of the log scan loop: either we came to the
 853          * known end of the log or we found an unexpected block in the
 854          * log.  If the latter happened, then we know that the "current"
 855          * transaction marks the end of the valid log.
 856          */
 857
 858         if (pass == PASS_SCAN) {
 859                 if (!info->end_transaction)
 860                         info->end_transaction = next_commit_ID;
 861         } else {
 862                 /* It's really bad news if different passes end up at
 863                  * different places (but possible due to IO errors). */
 864                 if (info->end_transaction != next_commit_ID) {
 865                         printk(KERN_ERR "JBD2: recovery pass %d ended at "
 866                                 "transaction %u, expected %u\n",
 867                                 pass, next_commit_ID, info->end_transaction);
 868                         if (!success)
 869                                 success = -EIO;
 870                 }
 871         }
 872
 873         if (jbd2_has_feature_fast_commit(journal) &&  pass != PASS_REVOKE) {
 874                 err = fc_do_one_pass(journal, info, pass);
 875                 if (err)
 876                         success = err;
 877         }
 878
 879         if (block_error && success == 0)
 880                 success = -EIO;
 881         return success;
 882
 883  failed:
 884         return err;
 885 }
 886
 887 /* Scan a revoke record, marking all blocks mentioned as revoked. */
 888
 889 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
 890                                tid_t sequence, struct recovery_info *info)
 891 {
 892         jbd2_journal_revoke_header_t *header;
 893         int offset, max;
 894         unsigned csum_size = 0;
 895         __u32 rcount;
 896         int record_len = 4;
 897
 898         header = (jbd2_journal_revoke_header_t *) bh->b_data;
 899         offset = sizeof(jbd2_journal_revoke_header_t);
 900         rcount = be32_to_cpu(header->r_count);
 901
 902         if (jbd2_journal_has_csum_v2or3(journal))
 903                 csum_size = sizeof(struct jbd2_journal_block_tail);
 904         if (rcount > journal->j_blocksize - csum_size)
 905                 return -EINVAL;
 906         max = rcount;
 907
 908         if (jbd2_has_feature_64bit(journal))
 909                 record_len = 8;
 910
 911         while (offset + record_len <= max) {
 912                 unsigned long long blocknr;
 913                 int err;
 914
 915                 if (record_len == 4)
 916                         blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
 917                 else
 918                         blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
 919                 offset += record_len;
 920                 err = jbd2_journal_set_revoke(journal, blocknr, sequence);
 921                 if (err)
 922                         return err;
 923                 ++info->nr_revokes;
 924         }
 925         return 0;
 926 }