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                                 bh_readahead_batch(nbufs, bufs, 0);
 104                                 journal_brelse_array(bufs, nbufs);
 105                                 nbufs = 0;
 106                         }
 107                 } else
 108                         brelse(bh);
 109         }
 110
 111         if (nbufs)
 112                 bh_readahead_batch(nbufs, bufs, 0);
 113         err = 0;
 114
 115 failed:
 116         if (nbufs)
 117                 journal_brelse_array(bufs, nbufs);
 118         return err;
 119 }
 120
 121 #endif /* __KERNEL__ */
 122
 123
 124 /*
 125  * Read a block from the journal
 126  */
 127
 128 static int jread(struct buffer_head **bhp, journal_t *journal,
 129                  unsigned int offset)
 130 {
 131         int err;
 132         unsigned long long blocknr;
 133         struct buffer_head *bh;
 134
 135         *bhp = NULL;
 136
 137         if (offset >= journal->j_total_len) {
 138                 printk(KERN_ERR "JBD2: corrupted journal superblock\n");
 139                 return -EFSCORRUPTED;
 140         }
 141
 142         err = jbd2_journal_bmap(journal, offset, &blocknr);
 143
 144         if (err) {
 145                 printk(KERN_ERR "JBD2: bad block at offset %u\n",
 146                         offset);
 147                 return err;
 148         }
 149
 150         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
 151         if (!bh)
 152                 return -ENOMEM;
 153
 154         if (!buffer_uptodate(bh)) {
 155                 /*
 156                  * If this is a brand new buffer, start readahead.
 157                  * Otherwise, we assume we are already reading it.
 158                  */
 159                 bool need_readahead = !buffer_req(bh);
 160
 161                 bh_read_nowait(bh, 0);
 162                 if (need_readahead)
 163                         do_readahead(journal, offset);
 164                 wait_on_buffer(bh);
 165         }
 166
 167         if (!buffer_uptodate(bh)) {
 168                 printk(KERN_ERR "JBD2: Failed to read block at offset %u\n",
 169                         offset);
 170                 brelse(bh);
 171                 return -EIO;
 172         }
 173
 174         *bhp = bh;
 175         return 0;
 176 }
 177
 178 static int jbd2_descriptor_block_csum_verify(journal_t *j, void *buf)
 179 {
 180         struct jbd2_journal_block_tail *tail;
 181         __be32 provided;
 182         __u32 calculated;
 183
 184         if (!jbd2_journal_has_csum_v2or3(j))
 185                 return 1;
 186
 187         tail = (struct jbd2_journal_block_tail *)((char *)buf +
 188                 j->j_blocksize - sizeof(struct jbd2_journal_block_tail));
 189         provided = tail->t_checksum;
 190         tail->t_checksum = 0;
 191         calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 192         tail->t_checksum = provided;
 193
 194         return provided == cpu_to_be32(calculated);
 195 }
 196
 197 /*
 198  * Count the number of in-use tags in a journal descriptor block.
 199  */
 200
 201 static int count_tags(journal_t *journal, struct buffer_head *bh)
 202 {
 203         char *                  tagp;
 204         journal_block_tag_t     tag;
 205         int                     nr = 0, size = journal->j_blocksize;
 206         int                     tag_bytes = journal_tag_bytes(journal);
 207
 208         if (jbd2_journal_has_csum_v2or3(journal))
 209                 size -= sizeof(struct jbd2_journal_block_tail);
 210
 211         tagp = &bh->b_data[sizeof(journal_header_t)];
 212
 213         while ((tagp - bh->b_data + tag_bytes) <= size) {
 214                 memcpy(&tag, tagp, sizeof(tag));
 215
 216                 nr++;
 217                 tagp += tag_bytes;
 218                 if (!(tag.t_flags & cpu_to_be16(JBD2_FLAG_SAME_UUID)))
 219                         tagp += 16;
 220
 221                 if (tag.t_flags & cpu_to_be16(JBD2_FLAG_LAST_TAG))
 222                         break;
 223         }
 224
 225         return nr;
 226 }
 227
 228
 229 /* Make sure we wrap around the log correctly! */
 230 #define wrap(journal, var)                                              \
 231 do {                                                                    \
 232         unsigned long _wrap_last =                                      \
 233                 jbd2_has_feature_fast_commit(journal) ?                 \
 234                         (journal)->j_fc_last : (journal)->j_last;       \
 235                                                                         \
 236         if (var >= _wrap_last)                                          \
 237                 var -= (_wrap_last - (journal)->j_first);               \
 238 } while (0)
 239
 240 static int fc_do_one_pass(journal_t *journal,
 241                           struct recovery_info *info, enum passtype pass)
 242 {
 243         unsigned int expected_commit_id = info->end_transaction;
 244         unsigned long next_fc_block;
 245         struct buffer_head *bh;
 246         int err = 0;
 247
 248         next_fc_block = journal->j_fc_first;
 249         if (!journal->j_fc_replay_callback)
 250                 return 0;
 251
 252         while (next_fc_block <= journal->j_fc_last) {
 253                 jbd2_debug(3, "Fast commit replay: next block %ld\n",
 254                           next_fc_block);
 255                 err = jread(&bh, journal, next_fc_block);
 256                 if (err) {
 257                         jbd2_debug(3, "Fast commit replay: read error\n");
 258                         break;
 259                 }
 260
 261                 err = journal->j_fc_replay_callback(journal, bh, pass,
 262                                         next_fc_block - journal->j_fc_first,
 263                                         expected_commit_id);
 264                 brelse(bh);
 265                 next_fc_block++;
 266                 if (err < 0 || err == JBD2_FC_REPLAY_STOP)
 267                         break;
 268                 err = 0;
 269         }
 270
 271         if (err)
 272                 jbd2_debug(3, "Fast commit replay failed, err = %d\n", err);
 273
 274         return err;
 275 }
 276
 277 /**
 278  * jbd2_journal_recover - recovers a on-disk journal
 279  * @journal: the journal to recover
 280  *
 281  * The primary function for recovering the log contents when mounting a
 282  * journaled device.
 283  *
 284  * Recovery is done in three passes.  In the first pass, we look for the
 285  * end of the log.  In the second, we assemble the list of revoke
 286  * blocks.  In the third and final pass, we replay any un-revoked blocks
 287  * in the log.
 288  */
 289 int jbd2_journal_recover(journal_t *journal)
 290 {
 291         int                     err, err2;
 292         journal_superblock_t *  sb;
 293
 294         struct recovery_info    info;
 295
 296         memset(&info, 0, sizeof(info));
 297         sb = journal->j_superblock;
 298
 299         /*
 300          * The journal superblock's s_start field (the current log head)
 301          * is always zero if, and only if, the journal was cleanly
 302          * unmounted.
 303          */
 304
 305         if (!sb->s_start) {
 306                 jbd2_debug(1, "No recovery required, last transaction %d\n",
 307                           be32_to_cpu(sb->s_sequence));
 308                 journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
 309                 return 0;
 310         }
 311
 312         err = do_one_pass(journal, &info, PASS_SCAN);
 313         if (!err)
 314                 err = do_one_pass(journal, &info, PASS_REVOKE);
 315         if (!err)
 316                 err = do_one_pass(journal, &info, PASS_REPLAY);
 317
 318         jbd2_debug(1, "JBD2: recovery, exit status %d, "
 319                   "recovered transactions %u to %u\n",
 320                   err, info.start_transaction, info.end_transaction);
 321         jbd2_debug(1, "JBD2: Replayed %d and revoked %d/%d blocks\n",
 322                   info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
 323
 324         /* Restart the log at the next transaction ID, thus invalidating
 325          * any existing commit records in the log. */
 326         journal->j_transaction_sequence = ++info.end_transaction;
 327
 328         jbd2_journal_clear_revoke(journal);
 329         err2 = sync_blockdev(journal->j_fs_dev);
 330         if (!err)
 331                 err = err2;
 332         /* Make sure all replayed data is on permanent storage */
 333         if (journal->j_flags & JBD2_BARRIER) {
 334                 err2 = blkdev_issue_flush(journal->j_fs_dev);
 335                 if (!err)
 336                         err = err2;
 337         }
 338         return err;
 339 }
 340
 341 /**
 342  * jbd2_journal_skip_recovery - Start journal and wipe exiting records
 343  * @journal: journal to startup
 344  *
 345  * Locate any valid recovery information from the journal and set up the
 346  * journal structures in memory to ignore it (presumably because the
 347  * caller has evidence that it is out of date).
 348  * This function doesn't appear to be exported..
 349  *
 350  * We perform one pass over the journal to allow us to tell the user how
 351  * much recovery information is being erased, and to let us initialise
 352  * the journal transaction sequence numbers to the next unused ID.
 353  */
 354 int jbd2_journal_skip_recovery(journal_t *journal)
 355 {
 356         int                     err;
 357
 358         struct recovery_info    info;
 359
 360         memset (&info, 0, sizeof(info));
 361
 362         err = do_one_pass(journal, &info, PASS_SCAN);
 363
 364         if (err) {
 365                 printk(KERN_ERR "JBD2: error %d scanning journal\n", err);
 366                 ++journal->j_transaction_sequence;
 367         } else {
 368 #ifdef CONFIG_JBD2_DEBUG
 369                 int dropped = info.end_transaction -
 370                         be32_to_cpu(journal->j_superblock->s_sequence);
 371                 jbd2_debug(1,
 372                           "JBD2: ignoring %d transaction%s from the journal.\n",
 373                           dropped, (dropped == 1) ? "" : "s");
 374 #endif
 375                 journal->j_transaction_sequence = ++info.end_transaction;
 376         }
 377
 378         journal->j_tail = 0;
 379         return err;
 380 }
 381
 382 static inline unsigned long long read_tag_block(journal_t *journal,
 383                                                 journal_block_tag_t *tag)
 384 {
 385         unsigned long long block = be32_to_cpu(tag->t_blocknr);
 386         if (jbd2_has_feature_64bit(journal))
 387                 block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
 388         return block;
 389 }
 390
 391 /*
 392  * calc_chksums calculates the checksums for the blocks described in the
 393  * descriptor block.
 394  */
 395 static int calc_chksums(journal_t *journal, struct buffer_head *bh,
 396                         unsigned long *next_log_block, __u32 *crc32_sum)
 397 {
 398         int i, num_blks, err;
 399         unsigned long io_block;
 400         struct buffer_head *obh;
 401
 402         num_blks = count_tags(journal, bh);
 403         /* Calculate checksum of the descriptor block. */
 404         *crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
 405
 406         for (i = 0; i < num_blks; i++) {
 407                 io_block = (*next_log_block)++;
 408                 wrap(journal, *next_log_block);
 409                 err = jread(&obh, journal, io_block);
 410                 if (err) {
 411                         printk(KERN_ERR "JBD2: IO error %d recovering block "
 412                                 "%lu in log\n", err, io_block);
 413                         return 1;
 414                 } else {
 415                         *crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
 416                                      obh->b_size);
 417                 }
 418                 put_bh(obh);
 419         }
 420         return 0;
 421 }
 422
 423 static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
 424 {
 425         struct commit_header *h;
 426         __be32 provided;
 427         __u32 calculated;
 428
 429         if (!jbd2_journal_has_csum_v2or3(j))
 430                 return 1;
 431
 432         h = buf;
 433         provided = h->h_chksum[0];
 434         h->h_chksum[0] = 0;
 435         calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 436         h->h_chksum[0] = provided;
 437
 438         return provided == cpu_to_be32(calculated);
 439 }
 440
 441 static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
 442                                       journal_block_tag3_t *tag3,
 443                                       void *buf, __u32 sequence)
 444 {
 445         __u32 csum32;
 446         __be32 seq;
 447
 448         if (!jbd2_journal_has_csum_v2or3(j))
 449                 return 1;
 450
 451         seq = cpu_to_be32(sequence);
 452         csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
 453         csum32 = jbd2_chksum(j, csum32, buf, j->j_blocksize);
 454
 455         if (jbd2_has_feature_csum3(j))
 456                 return tag3->t_checksum == cpu_to_be32(csum32);
 457         else
 458                 return tag->t_checksum == cpu_to_be16(csum32);
 459 }
 460
 461 static int do_one_pass(journal_t *journal,
 462                         struct recovery_info *info, enum passtype pass)
 463 {
 464         unsigned int            first_commit_ID, next_commit_ID;
 465         unsigned long           next_log_block;
 466         int                     err, success = 0;
 467         journal_superblock_t *  sb;
 468         journal_header_t *      tmp;
 469         struct buffer_head *    bh;
 470         unsigned int            sequence;
 471         int                     blocktype;
 472         int                     tag_bytes = journal_tag_bytes(journal);
 473         __u32                   crc32_sum = ~0; /* Transactional Checksums */
 474         int                     descr_csum_size = 0;
 475         int                     block_error = 0;
 476         bool                    need_check_commit_time = false;
 477         __u64                   last_trans_commit_time = 0, commit_time;
 478
 479         /*
 480          * First thing is to establish what we expect to find in the log
 481          * (in terms of transaction IDs), and where (in terms of log
 482          * block offsets): query the superblock.
 483          */
 484
 485         sb = journal->j_superblock;
 486         next_commit_ID = be32_to_cpu(sb->s_sequence);
 487         next_log_block = be32_to_cpu(sb->s_start);
 488
 489         first_commit_ID = next_commit_ID;
 490         if (pass == PASS_SCAN)
 491                 info->start_transaction = first_commit_ID;
 492
 493         jbd2_debug(1, "Starting recovery pass %d\n", pass);
 494
 495         /*
 496          * Now we walk through the log, transaction by transaction,
 497          * making sure that each transaction has a commit block in the
 498          * expected place.  Each complete transaction gets replayed back
 499          * into the main filesystem.
 500          */
 501
 502         while (1) {
 503                 int                     flags;
 504                 char *                  tagp;
 505                 journal_block_tag_t     tag;
 506                 struct buffer_head *    obh;
 507                 struct buffer_head *    nbh;
 508
 509                 cond_resched();
 510
 511                 /* If we already know where to stop the log traversal,
 512                  * check right now that we haven't gone past the end of
 513                  * the log. */
 514
 515                 if (pass != PASS_SCAN)
 516                         if (tid_geq(next_commit_ID, info->end_transaction))
 517                                 break;
 518
 519                 jbd2_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
 520                           next_commit_ID, next_log_block,
 521                           jbd2_has_feature_fast_commit(journal) ?
 522                           journal->j_fc_last : journal->j_last);
 523
 524                 /* Skip over each chunk of the transaction looking
 525                  * either the next descriptor block or the final commit
 526                  * record. */
 527
 528                 jbd2_debug(3, "JBD2: checking block %ld\n", next_log_block);
 529                 err = jread(&bh, journal, next_log_block);
 530                 if (err)
 531                         goto failed;
 532
 533                 next_log_block++;
 534                 wrap(journal, next_log_block);
 535
 536                 /* What kind of buffer is it?
 537                  *
 538                  * If it is a descriptor block, check that it has the
 539                  * expected sequence number.  Otherwise, we're all done
 540                  * here. */
 541
 542                 tmp = (journal_header_t *)bh->b_data;
 543
 544                 if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
 545                         brelse(bh);
 546                         break;
 547                 }
 548
 549                 blocktype = be32_to_cpu(tmp->h_blocktype);
 550                 sequence = be32_to_cpu(tmp->h_sequence);
 551                 jbd2_debug(3, "Found magic %d, sequence %d\n",
 552                           blocktype, sequence);
 553
 554                 if (sequence != next_commit_ID) {
 555                         brelse(bh);
 556                         break;
 557                 }
 558
 559                 /* OK, we have a valid descriptor block which matches
 560                  * all of the sequence number checks.  What are we going
 561                  * to do with it?  That depends on the pass... */
 562
 563                 switch(blocktype) {
 564                 case JBD2_DESCRIPTOR_BLOCK:
 565                         /* Verify checksum first */
 566                         if (jbd2_journal_has_csum_v2or3(journal))
 567                                 descr_csum_size =
 568                                         sizeof(struct jbd2_journal_block_tail);
 569                         if (descr_csum_size > 0 &&
 570                             !jbd2_descriptor_block_csum_verify(journal,
 571                                                                bh->b_data)) {
 572                                 /*
 573                                  * PASS_SCAN can see stale blocks due to lazy
 574                                  * journal init. Don't error out on those yet.
 575                                  */
 576                                 if (pass != PASS_SCAN) {
 577                                         pr_err("JBD2: Invalid checksum recovering block %lu in log\n",
 578                                                next_log_block);
 579                                         err = -EFSBADCRC;
 580                                         brelse(bh);
 581                                         goto failed;
 582                                 }
 583                                 need_check_commit_time = true;
 584                                 jbd2_debug(1,
 585                                         "invalid descriptor block found in %lu\n",
 586                                         next_log_block);
 587                         }
 588
 589                         /* If it is a valid descriptor block, replay it
 590                          * in pass REPLAY; if journal_checksums enabled, then
 591                          * calculate checksums in PASS_SCAN, otherwise,
 592                          * just skip over the blocks it describes. */
 593                         if (pass != PASS_REPLAY) {
 594                                 if (pass == PASS_SCAN &&
 595                                     jbd2_has_feature_checksum(journal) &&
 596                                     !need_check_commit_time &&
 597                                     !info->end_transaction) {
 598                                         if (calc_chksums(journal, bh,
 599                                                         &next_log_block,
 600                                                         &crc32_sum)) {
 601                                                 put_bh(bh);
 602                                                 break;
 603                                         }
 604                                         put_bh(bh);
 605                                         continue;
 606                                 }
 607                                 next_log_block += count_tags(journal, bh);
 608                                 wrap(journal, next_log_block);
 609                                 put_bh(bh);
 610                                 continue;
 611                         }
 612
 613                         /* A descriptor block: we can now write all of
 614                          * the data blocks.  Yay, useful work is finally
 615                          * getting done here! */
 616
 617                         tagp = &bh->b_data[sizeof(journal_header_t)];
 618                         while ((tagp - bh->b_data + tag_bytes)
 619                                <= journal->j_blocksize - descr_csum_size) {
 620                                 unsigned long io_block;
 621
 622                                 memcpy(&tag, tagp, sizeof(tag));
 623                                 flags = be16_to_cpu(tag.t_flags);
 624
 625                                 io_block = next_log_block++;
 626                                 wrap(journal, next_log_block);
 627                                 err = jread(&obh, journal, io_block);
 628                                 if (err) {
 629                                         /* Recover what we can, but
 630                                          * report failure at the end. */
 631                                         success = err;
 632                                         printk(KERN_ERR
 633                                                 "JBD2: IO error %d recovering "
 634                                                 "block %ld in log\n",
 635                                                 err, io_block);
 636                                 } else {
 637                                         unsigned long long blocknr;
 638
 639                                         J_ASSERT(obh != NULL);
 640                                         blocknr = read_tag_block(journal,
 641                                                                  &tag);
 642
 643                                         /* If the block has been
 644                                          * revoked, then we're all done
 645                                          * here. */
 646                                         if (jbd2_journal_test_revoke
 647                                             (journal, blocknr,
 648                                              next_commit_ID)) {
 649                                                 brelse(obh);
 650                                                 ++info->nr_revoke_hits;
 651                                                 goto skip_write;
 652                                         }
 653
 654                                         /* Look for block corruption */
 655                                         if (!jbd2_block_tag_csum_verify(
 656                         journal, &tag, (journal_block_tag3_t *)tagp,
 657                         obh->b_data, be32_to_cpu(tmp->h_sequence))) {
 658                                                 brelse(obh);
 659                                                 success = -EFSBADCRC;
 660                                                 printk(KERN_ERR "JBD2: Invalid "
 661                                                        "checksum recovering "
 662                                                        "data block %llu in "
 663                                                        "log\n", blocknr);
 664                                                 block_error = 1;
 665                                                 goto skip_write;
 666                                         }
 667
 668                                         /* Find a buffer for the new
 669                                          * data being restored */
 670                                         nbh = __getblk(journal->j_fs_dev,
 671                                                         blocknr,
 672                                                         journal->j_blocksize);
 673                                         if (nbh == NULL) {
 674                                                 printk(KERN_ERR
 675                                                        "JBD2: Out of memory "
 676                                                        "during recovery.\n");
 677                                                 err = -ENOMEM;
 678                                                 brelse(bh);
 679                                                 brelse(obh);
 680                                                 goto failed;
 681                                         }
 682
 683                                         lock_buffer(nbh);
 684                                         memcpy(nbh->b_data, obh->b_data,
 685                                                         journal->j_blocksize);
 686                                         if (flags & JBD2_FLAG_ESCAPE) {
 687                                                 *((__be32 *)nbh->b_data) =
 688                                                 cpu_to_be32(JBD2_MAGIC_NUMBER);
 689                                         }
 690
 691                                         BUFFER_TRACE(nbh, "marking dirty");
 692                                         set_buffer_uptodate(nbh);
 693                                         mark_buffer_dirty(nbh);
 694                                         BUFFER_TRACE(nbh, "marking uptodate");
 695                                         ++info->nr_replays;
 696                                         unlock_buffer(nbh);
 697                                         brelse(obh);
 698                                         brelse(nbh);
 699                                 }
 700
 701                         skip_write:
 702                                 tagp += tag_bytes;
 703                                 if (!(flags & JBD2_FLAG_SAME_UUID))
 704                                         tagp += 16;
 705
 706                                 if (flags & JBD2_FLAG_LAST_TAG)
 707                                         break;
 708                         }
 709
 710                         brelse(bh);
 711                         continue;
 712
 713                 case JBD2_COMMIT_BLOCK:
 714                         /*     How to differentiate between interrupted commit
 715                          *               and journal corruption ?
 716                          *
 717                          * {nth transaction}
 718                          *        Checksum Verification Failed
 719                          *                       |
 720                          *               ____________________
 721                          *              |                    |
 722                          *      async_commit             sync_commit
 723                          *              |                    |
 724                          *              | GO TO NEXT    "Journal Corruption"
 725                          *              | TRANSACTION
 726                          *              |
 727                          * {(n+1)th transanction}
 728                          *              |
 729                          *       _______|______________
 730                          *      |                     |
 731                          * Commit block found   Commit block not found
 732                          *      |                     |
 733                          * "Journal Corruption"       |
 734                          *               _____________|_________
 735                          *              |                       |
 736                          *      nth trans corrupt       OR   nth trans
 737                          *      and (n+1)th interrupted     interrupted
 738                          *      before commit block
 739                          *      could reach the disk.
 740                          *      (Cannot find the difference in above
 741                          *       mentioned conditions. Hence assume
 742                          *       "Interrupted Commit".)
 743                          */
 744                         commit_time = be64_to_cpu(
 745                                 ((struct commit_header *)bh->b_data)->h_commit_sec);
 746                         /*
 747                          * If need_check_commit_time is set, it means we are in
 748                          * PASS_SCAN and csum verify failed before. If
 749                          * commit_time is increasing, it's the same journal,
 750                          * otherwise it is stale journal block, just end this
 751                          * recovery.
 752                          */
 753                         if (need_check_commit_time) {
 754                                 if (commit_time >= last_trans_commit_time) {
 755                                         pr_err("JBD2: Invalid checksum found in transaction %u\n",
 756                                                next_commit_ID);
 757                                         err = -EFSBADCRC;
 758                                         brelse(bh);
 759                                         goto failed;
 760                                 }
 761                         ignore_crc_mismatch:
 762                                 /*
 763                                  * It likely does not belong to same journal,
 764                                  * just end this recovery with success.
 765                                  */
 766                                 jbd2_debug(1, "JBD2: Invalid checksum ignored in transaction %u, likely stale data\n",
 767                                           next_commit_ID);
 768                                 brelse(bh);
 769                                 goto done;
 770                         }
 771
 772                         /*
 773                          * Found an expected commit block: if checksums
 774                          * are present, verify them in PASS_SCAN; else not
 775                          * much to do other than move on to the next sequence
 776                          * number.
 777                          */
 778                         if (pass == PASS_SCAN &&
 779                             jbd2_has_feature_checksum(journal)) {
 780                                 struct commit_header *cbh =
 781                                         (struct commit_header *)bh->b_data;
 782                                 unsigned found_chksum =
 783                                         be32_to_cpu(cbh->h_chksum[0]);
 784
 785                                 if (info->end_transaction) {
 786                                         journal->j_failed_commit =
 787                                                 info->end_transaction;
 788                                         brelse(bh);
 789                                         break;
 790                                 }
 791
 792                                 /* Neither checksum match nor unused? */
 793                                 if (!((crc32_sum == found_chksum &&
 794                                        cbh->h_chksum_type ==
 795                                                 JBD2_CRC32_CHKSUM &&
 796                                        cbh->h_chksum_size ==
 797                                                 JBD2_CRC32_CHKSUM_SIZE) ||
 798                                       (cbh->h_chksum_type == 0 &&
 799                                        cbh->h_chksum_size == 0 &&
 800                                        found_chksum == 0)))
 801                                         goto chksum_error;
 802
 803                                 crc32_sum = ~0;
 804                         }
 805                         if (pass == PASS_SCAN &&
 806                             !jbd2_commit_block_csum_verify(journal,
 807                                                            bh->b_data)) {
 808                         chksum_error:
 809                                 if (commit_time < last_trans_commit_time)
 810                                         goto ignore_crc_mismatch;
 811                                 info->end_transaction = next_commit_ID;
 812
 813                                 if (!jbd2_has_feature_async_commit(journal)) {
 814                                         journal->j_failed_commit =
 815                                                 next_commit_ID;
 816                                         brelse(bh);
 817                                         break;
 818                                 }
 819                         }
 820                         if (pass == PASS_SCAN)
 821                                 last_trans_commit_time = commit_time;
 822                         brelse(bh);
 823                         next_commit_ID++;
 824                         continue;
 825
 826                 case JBD2_REVOKE_BLOCK:
 827                         /*
 828                          * Check revoke block crc in pass_scan, if csum verify
 829                          * failed, check commit block time later.
 830                          */
 831                         if (pass == PASS_SCAN &&
 832                             !jbd2_descriptor_block_csum_verify(journal,
 833                                                                bh->b_data)) {
 834                                 jbd2_debug(1, "JBD2: invalid revoke block found in %lu\n",
 835                                           next_log_block);
 836                                 need_check_commit_time = true;
 837                         }
 838                         /* If we aren't in the REVOKE pass, then we can
 839                          * just skip over this block. */
 840                         if (pass != PASS_REVOKE) {
 841                                 brelse(bh);
 842                                 continue;
 843                         }
 844
 845                         err = scan_revoke_records(journal, bh,
 846                                                   next_commit_ID, info);
 847                         brelse(bh);
 848                         if (err)
 849                                 goto failed;
 850                         continue;
 851
 852                 default:
 853                         jbd2_debug(3, "Unrecognised magic %d, end of scan.\n",
 854                                   blocktype);
 855                         brelse(bh);
 856                         goto done;
 857                 }
 858         }
 859
 860  done:
 861         /*
 862          * We broke out of the log scan loop: either we came to the
 863          * known end of the log or we found an unexpected block in the
 864          * log.  If the latter happened, then we know that the "current"
 865          * transaction marks the end of the valid log.
 866          */
 867
 868         if (pass == PASS_SCAN) {
 869                 if (!info->end_transaction)
 870                         info->end_transaction = next_commit_ID;
 871         } else {
 872                 /* It's really bad news if different passes end up at
 873                  * different places (but possible due to IO errors). */
 874                 if (info->end_transaction != next_commit_ID) {
 875                         printk(KERN_ERR "JBD2: recovery pass %d ended at "
 876                                 "transaction %u, expected %u\n",
 877                                 pass, next_commit_ID, info->end_transaction);
 878                         if (!success)
 879                                 success = -EIO;
 880                 }
 881         }
 882
 883         if (jbd2_has_feature_fast_commit(journal) &&  pass != PASS_REVOKE) {
 884                 err = fc_do_one_pass(journal, info, pass);
 885                 if (err)
 886                         success = err;
 887         }
 888
 889         if (block_error && success == 0)
 890                 success = -EIO;
 891         return success;
 892
 893  failed:
 894         return err;
 895 }
 896
 897 /* Scan a revoke record, marking all blocks mentioned as revoked. */
 898
 899 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
 900                                tid_t sequence, struct recovery_info *info)
 901 {
 902         jbd2_journal_revoke_header_t *header;
 903         int offset, max;
 904         unsigned csum_size = 0;
 905         __u32 rcount;
 906         int record_len = 4;
 907
 908         header = (jbd2_journal_revoke_header_t *) bh->b_data;
 909         offset = sizeof(jbd2_journal_revoke_header_t);
 910         rcount = be32_to_cpu(header->r_count);
 911
 912         if (jbd2_journal_has_csum_v2or3(journal))
 913                 csum_size = sizeof(struct jbd2_journal_block_tail);
 914         if (rcount > journal->j_blocksize - csum_size)
 915                 return -EINVAL;
 916         max = rcount;
 917
 918         if (jbd2_has_feature_64bit(journal))
 919                 record_len = 8;
 920
 921         while (offset + record_len <= max) {
 922                 unsigned long long blocknr;
 923                 int err;
 924
 925                 if (record_len == 4)
 926                         blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
 927                 else
 928                         blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
 929                 offset += record_len;
 930                 err = jbd2_journal_set_revoke(journal, blocknr, sequence);
 931                 if (err)
 932                         return err;
 933                 ++info->nr_revokes;
 934         }
 935         return 0;
 936 }