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