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         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
 235 static 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  */
 283 int 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  */
 348 int 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
 376 static 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  */
 389 static 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
 417 static 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
 435 static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
 436                                       journal_block_tag3_t *tag3,
 437                                       void *buf, __u32 sequence)
 438 {
 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
 455 static 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                                 memcpy(&tag, tagp, sizeof(tag));
 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, (journal_block_tag3_t *)tagp,
 651                         obh->b_data, 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                                 brelse(bh);
 764                                 goto done;
 765                         }
 766
 767                         /*
 768                          * Found an expected commit block: if checksums
 769                          * are present, verify them in PASS_SCAN; else not
 770                          * much to do other than move on to the next sequence
 771                          * number.
 772                          */
 773                         if (pass == PASS_SCAN &&
 774                             jbd2_has_feature_checksum(journal)) {
 775                                 struct commit_header *cbh =
 776                                         (struct commit_header *)bh->b_data;
 777                                 unsigned found_chksum =
 778                                         be32_to_cpu(cbh->h_chksum[0]);
 779
 780                                 if (info->end_transaction) {
 781                                         journal->j_failed_commit =
 782                                                 info->end_transaction;
 783                                         brelse(bh);
 784                                         break;
 785                                 }
 786
 787                                 /* Neither checksum match nor unused? */
 788                                 if (!((crc32_sum == found_chksum &&
 789                                        cbh->h_chksum_type ==
 790                                                 JBD2_CRC32_CHKSUM &&
 791                                        cbh->h_chksum_size ==
 792                                                 JBD2_CRC32_CHKSUM_SIZE) ||
 793                                       (cbh->h_chksum_type == 0 &&
 794                                        cbh->h_chksum_size == 0 &&
 795                                        found_chksum == 0)))
 796                                         goto chksum_error;
 797
 798                                 crc32_sum = ~0;
 799                         }
 800                         if (pass == PASS_SCAN &&
 801                             !jbd2_commit_block_csum_verify(journal,
 802                                                            bh->b_data)) {
 803                         chksum_error:
 804                                 if (commit_time < last_trans_commit_time)
 805                                         goto ignore_crc_mismatch;
 806                                 info->end_transaction = next_commit_ID;
 807
 808                                 if (!jbd2_has_feature_async_commit(journal)) {
 809                                         journal->j_failed_commit =
 810                                                 next_commit_ID;
 811                                         brelse(bh);
 812                                         break;
 813                                 }
 814                         }
 815                         if (pass == PASS_SCAN)
 816                                 last_trans_commit_time = commit_time;
 817                         brelse(bh);
 818                         next_commit_ID++;
 819                         continue;
 820
 821                 case JBD2_REVOKE_BLOCK:
 822                         /*
 823                          * Check revoke block crc in pass_scan, if csum verify
 824                          * failed, check commit block time later.
 825                          */
 826                         if (pass == PASS_SCAN &&
 827                             !jbd2_descriptor_block_csum_verify(journal,
 828                                                                bh->b_data)) {
 829                                 jbd_debug(1, "JBD2: invalid revoke block found in %lu\n",
 830                                           next_log_block);
 831                                 need_check_commit_time = true;
 832                         }
 833                         /* If we aren't in the REVOKE pass, then we can
 834                          * just skip over this block. */
 835                         if (pass != PASS_REVOKE) {
 836                                 brelse(bh);
 837                                 continue;
 838                         }
 839
 840                         err = scan_revoke_records(journal, bh,
 841                                                   next_commit_ID, info);
 842                         brelse(bh);
 843                         if (err)
 844                                 goto failed;
 845                         continue;
 846
 847                 default:
 848                         jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
 849                                   blocktype);
 850                         brelse(bh);
 851                         goto done;
 852                 }
 853         }
 854
 855  done:
 856         /*
 857          * We broke out of the log scan loop: either we came to the
 858          * known end of the log or we found an unexpected block in the
 859          * log.  If the latter happened, then we know that the "current"
 860          * transaction marks the end of the valid log.
 861          */
 862
 863         if (pass == PASS_SCAN) {
 864                 if (!info->end_transaction)
 865                         info->end_transaction = next_commit_ID;
 866         } else {
 867                 /* It's really bad news if different passes end up at
 868                  * different places (but possible due to IO errors). */
 869                 if (info->end_transaction != next_commit_ID) {
 870                         printk(KERN_ERR "JBD2: recovery pass %d ended at "
 871                                 "transaction %u, expected %u\n",
 872                                 pass, next_commit_ID, info->end_transaction);
 873                         if (!success)
 874                                 success = -EIO;
 875                 }
 876         }
 877
 878         if (jbd2_has_feature_fast_commit(journal) &&  pass != PASS_REVOKE) {
 879                 err = fc_do_one_pass(journal, info, pass);
 880                 if (err)
 881                         success = err;
 882         }
 883
 884         if (block_error && success == 0)
 885                 success = -EIO;
 886         return success;
 887
 888  failed:
 889         return err;
 890 }
 891
 892 /* Scan a revoke record, marking all blocks mentioned as revoked. */
 893
 894 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
 895                                tid_t sequence, struct recovery_info *info)
 896 {
 897         jbd2_journal_revoke_header_t *header;
 898         int offset, max;
 899         unsigned csum_size = 0;
 900         __u32 rcount;
 901         int record_len = 4;
 902
 903         header = (jbd2_journal_revoke_header_t *) bh->b_data;
 904         offset = sizeof(jbd2_journal_revoke_header_t);
 905         rcount = be32_to_cpu(header->r_count);
 906
 907         if (jbd2_journal_has_csum_v2or3(journal))
 908                 csum_size = sizeof(struct jbd2_journal_block_tail);
 909         if (rcount > journal->j_blocksize - csum_size)
 910                 return -EINVAL;
 911         max = rcount;
 912
 913         if (jbd2_has_feature_64bit(journal))
 914                 record_len = 8;
 915
 916         while (offset + record_len <= max) {
 917                 unsigned long long blocknr;
 918                 int err;
 919
 920                 if (record_len == 4)
 921                         blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
 922                 else
 923                         blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
 924                 offset += record_len;
 925                 err = jbd2_journal_set_revoke(journal, blocknr, sequence);
 926                 if (err)
 927                         return err;
 928                 ++info->nr_revokes;
 929         }
 930         return 0;
 931 }