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\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                 brelse(bh);
 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         errseq_t                wb_err;
 291         struct address_space    *mapping;
 292
 293         memset(&info, 0, sizeof(info));
 294         sb = journal->j_superblock;
 295
 296         /*
 297          * The journal superblock's s_start field (the current log head)
 298          * is always zero if, and only if, the journal was cleanly
 299          * unmounted.
 300          */
 301
 302         if (!sb->s_start) {
 303                 jbd_debug(1, "No recovery required, last transaction %d\n",
 304                           be32_to_cpu(sb->s_sequence));
 305                 journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
 306                 return 0;
 307         }
 308
 309         wb_err = 0;
 310         mapping = journal->j_fs_dev->bd_inode->i_mapping;
 311         errseq_check_and_advance(&mapping->wb_err, &wb_err);
 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         jbd_debug(1, "JBD2: recovery, exit status %d, "
 319                   "recovered transactions %u to %u\n",
 320                   err, info.start_transaction, info.end_transaction);
 321         jbd_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         err2 = errseq_check_and_advance(&mapping->wb_err, &wb_err);
 333         if (!err)
 334                 err = err2;
 335         /* Make sure all replayed data is on permanent storage */
 336         if (journal->j_flags & JBD2_BARRIER) {
 337                 err2 = blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL);
 338                 if (!err)
 339                         err = err2;
 340         }
 341         return err;
 342 }
 343
 344 /**
 345  * jbd2_journal_skip_recovery - Start journal and wipe exiting records
 346  * @journal: journal to startup
 347  *
 348  * Locate any valid recovery information from the journal and set up the
 349  * journal structures in memory to ignore it (presumably because the
 350  * caller has evidence that it is out of date).
 351  * This function doesn't appear to be exported..
 352  *
 353  * We perform one pass over the journal to allow us to tell the user how
 354  * much recovery information is being erased, and to let us initialise
 355  * the journal transaction sequence numbers to the next unused ID.
 356  */
 357 int jbd2_journal_skip_recovery(journal_t *journal)
 358 {
 359         int                     err;
 360
 361         struct recovery_info    info;
 362
 363         memset (&info, 0, sizeof(info));
 364
 365         err = do_one_pass(journal, &info, PASS_SCAN);
 366
 367         if (err) {
 368                 printk(KERN_ERR "JBD2: error %d scanning journal\n", err);
 369                 ++journal->j_transaction_sequence;
 370         } else {
 371 #ifdef CONFIG_JBD2_DEBUG
 372                 int dropped = info.end_transaction -
 373                         be32_to_cpu(journal->j_superblock->s_sequence);
 374                 jbd_debug(1,
 375                           "JBD2: ignoring %d transaction%s from the journal.\n",
 376                           dropped, (dropped == 1) ? "" : "s");
 377 #endif
 378                 journal->j_transaction_sequence = ++info.end_transaction;
 379         }
 380
 381         journal->j_tail = 0;
 382         return err;
 383 }
 384
 385 static inline unsigned long long read_tag_block(journal_t *journal,
 386                                                 journal_block_tag_t *tag)
 387 {
 388         unsigned long long block = be32_to_cpu(tag->t_blocknr);
 389         if (jbd2_has_feature_64bit(journal))
 390                 block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
 391         return block;
 392 }
 393
 394 /*
 395  * calc_chksums calculates the checksums for the blocks described in the
 396  * descriptor block.
 397  */
 398 static int calc_chksums(journal_t *journal, struct buffer_head *bh,
 399                         unsigned long *next_log_block, __u32 *crc32_sum)
 400 {
 401         int i, num_blks, err;
 402         unsigned long io_block;
 403         struct buffer_head *obh;
 404
 405         num_blks = count_tags(journal, bh);
 406         /* Calculate checksum of the descriptor block. */
 407         *crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
 408
 409         for (i = 0; i < num_blks; i++) {
 410                 io_block = (*next_log_block)++;
 411                 wrap(journal, *next_log_block);
 412                 err = jread(&obh, journal, io_block);
 413                 if (err) {
 414                         printk(KERN_ERR "JBD2: IO error %d recovering block "
 415                                 "%lu in log\n", err, io_block);
 416                         return 1;
 417                 } else {
 418                         *crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
 419                                      obh->b_size);
 420                 }
 421                 put_bh(obh);
 422         }
 423         return 0;
 424 }
 425
 426 static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
 427 {
 428         struct commit_header *h;
 429         __be32 provided;
 430         __u32 calculated;
 431
 432         if (!jbd2_journal_has_csum_v2or3(j))
 433                 return 1;
 434
 435         h = buf;
 436         provided = h->h_chksum[0];
 437         h->h_chksum[0] = 0;
 438         calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 439         h->h_chksum[0] = provided;
 440
 441         return provided == cpu_to_be32(calculated);
 442 }
 443
 444 static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
 445                                       void *buf, __u32 sequence)
 446 {
 447         journal_block_tag3_t *tag3 = (journal_block_tag3_t *)tag;
 448         __u32 csum32;
 449         __be32 seq;
 450
 451         if (!jbd2_journal_has_csum_v2or3(j))
 452                 return 1;
 453
 454         seq = cpu_to_be32(sequence);
 455         csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
 456         csum32 = jbd2_chksum(j, csum32, buf, j->j_blocksize);
 457
 458         if (jbd2_has_feature_csum3(j))
 459                 return tag3->t_checksum == cpu_to_be32(csum32);
 460         else
 461                 return tag->t_checksum == cpu_to_be16(csum32);
 462 }
 463
 464 static int do_one_pass(journal_t *journal,
 465                         struct recovery_info *info, enum passtype pass)
 466 {
 467         unsigned int            first_commit_ID, next_commit_ID;
 468         unsigned long           next_log_block;
 469         int                     err, success = 0;
 470         journal_superblock_t *  sb;
 471         journal_header_t *      tmp;
 472         struct buffer_head *    bh;
 473         unsigned int            sequence;
 474         int                     blocktype;
 475         int                     tag_bytes = journal_tag_bytes(journal);
 476         __u32                   crc32_sum = ~0; /* Transactional Checksums */
 477         int                     descr_csum_size = 0;
 478         int                     block_error = 0;
 479         bool                    need_check_commit_time = false;
 480         __u64                   last_trans_commit_time = 0, commit_time;
 481
 482         /*
 483          * First thing is to establish what we expect to find in the log
 484          * (in terms of transaction IDs), and where (in terms of log
 485          * block offsets): query the superblock.
 486          */
 487
 488         sb = journal->j_superblock;
 489         next_commit_ID = be32_to_cpu(sb->s_sequence);
 490         next_log_block = be32_to_cpu(sb->s_start);
 491
 492         first_commit_ID = next_commit_ID;
 493         if (pass == PASS_SCAN)
 494                 info->start_transaction = first_commit_ID;
 495
 496         jbd_debug(1, "Starting recovery pass %d\n", pass);
 497
 498         /*
 499          * Now we walk through the log, transaction by transaction,
 500          * making sure that each transaction has a commit block in the
 501          * expected place.  Each complete transaction gets replayed back
 502          * into the main filesystem.
 503          */
 504
 505         while (1) {
 506                 int                     flags;
 507                 char *                  tagp;
 508                 journal_block_tag_t *   tag;
 509                 struct buffer_head *    obh;
 510                 struct buffer_head *    nbh;
 511
 512                 cond_resched();
 513
 514                 /* If we already know where to stop the log traversal,
 515                  * check right now that we haven't gone past the end of
 516                  * the log. */
 517
 518                 if (pass != PASS_SCAN)
 519                         if (tid_geq(next_commit_ID, info->end_transaction))
 520                                 break;
 521
 522                 jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
 523                           next_commit_ID, next_log_block,
 524                           jbd2_has_feature_fast_commit(journal) ?
 525                           journal->j_fc_last : journal->j_last);
 526
 527                 /* Skip over each chunk of the transaction looking
 528                  * either the next descriptor block or the final commit
 529                  * record. */
 530
 531                 jbd_debug(3, "JBD2: checking block %ld\n", next_log_block);
 532                 err = jread(&bh, journal, next_log_block);
 533                 if (err)
 534                         goto failed;
 535
 536                 next_log_block++;
 537                 wrap(journal, next_log_block);
 538
 539                 /* What kind of buffer is it?
 540                  *
 541                  * If it is a descriptor block, check that it has the
 542                  * expected sequence number.  Otherwise, we're all done
 543                  * here. */
 544
 545                 tmp = (journal_header_t *)bh->b_data;
 546
 547                 if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
 548                         brelse(bh);
 549                         break;
 550                 }
 551
 552                 blocktype = be32_to_cpu(tmp->h_blocktype);
 553                 sequence = be32_to_cpu(tmp->h_sequence);
 554                 jbd_debug(3, "Found magic %d, sequence %d\n",
 555                           blocktype, sequence);
 556
 557                 if (sequence != next_commit_ID) {
 558                         brelse(bh);
 559                         break;
 560                 }
 561
 562                 /* OK, we have a valid descriptor block which matches
 563                  * all of the sequence number checks.  What are we going
 564                  * to do with it?  That depends on the pass... */
 565
 566                 switch(blocktype) {
 567                 case JBD2_DESCRIPTOR_BLOCK:
 568                         /* Verify checksum first */
 569                         if (jbd2_journal_has_csum_v2or3(journal))
 570                                 descr_csum_size =
 571                                         sizeof(struct jbd2_journal_block_tail);
 572                         if (descr_csum_size > 0 &&
 573                             !jbd2_descriptor_block_csum_verify(journal,
 574                                                                bh->b_data)) {
 575                                 /*
 576                                  * PASS_SCAN can see stale blocks due to lazy
 577                                  * journal init. Don't error out on those yet.
 578                                  */
 579                                 if (pass != PASS_SCAN) {
 580                                         pr_err("JBD2: Invalid checksum recovering block %lu in log\n",
 581                                                next_log_block);
 582                                         err = -EFSBADCRC;
 583                                         brelse(bh);
 584                                         goto failed;
 585                                 }
 586                                 need_check_commit_time = true;
 587                                 jbd_debug(1,
 588                                         "invalid descriptor block found in %lu\n",
 589                                         next_log_block);
 590                         }
 591
 592                         /* If it is a valid descriptor block, replay it
 593                          * in pass REPLAY; if journal_checksums enabled, then
 594                          * calculate checksums in PASS_SCAN, otherwise,
 595                          * just skip over the blocks it describes. */
 596                         if (pass != PASS_REPLAY) {
 597                                 if (pass == PASS_SCAN &&
 598                                     jbd2_has_feature_checksum(journal) &&
 599                                     !need_check_commit_time &&
 600                                     !info->end_transaction) {
 601                                         if (calc_chksums(journal, bh,
 602                                                         &next_log_block,
 603                                                         &crc32_sum)) {
 604                                                 put_bh(bh);
 605                                                 break;
 606                                         }
 607                                         put_bh(bh);
 608                                         continue;
 609                                 }
 610                                 next_log_block += count_tags(journal, bh);
 611                                 wrap(journal, next_log_block);
 612                                 put_bh(bh);
 613                                 continue;
 614                         }
 615
 616                         /* A descriptor block: we can now write all of
 617                          * the data blocks.  Yay, useful work is finally
 618                          * getting done here! */
 619
 620                         tagp = &bh->b_data[sizeof(journal_header_t)];
 621                         while ((tagp - bh->b_data + tag_bytes)
 622                                <= journal->j_blocksize - descr_csum_size) {
 623                                 unsigned long io_block;
 624
 625                                 tag = (journal_block_tag_t *) tagp;
 626                                 flags = be16_to_cpu(tag->t_flags);
 627
 628                                 io_block = next_log_block++;
 629                                 wrap(journal, next_log_block);
 630                                 err = jread(&obh, journal, io_block);
 631                                 if (err) {
 632                                         /* Recover what we can, but
 633                                          * report failure at the end. */
 634                                         success = err;
 635                                         printk(KERN_ERR
 636                                                 "JBD2: IO error %d recovering "
 637                                                 "block %ld in log\n",
 638                                                 err, io_block);
 639                                 } else {
 640                                         unsigned long long blocknr;
 641
 642                                         J_ASSERT(obh != NULL);
 643                                         blocknr = read_tag_block(journal,
 644                                                                  tag);
 645
 646                                         /* If the block has been
 647                                          * revoked, then we're all done
 648                                          * here. */
 649                                         if (jbd2_journal_test_revoke
 650                                             (journal, blocknr,
 651                                              next_commit_ID)) {
 652                                                 brelse(obh);
 653                                                 ++info->nr_revoke_hits;
 654                                                 goto skip_write;
 655                                         }
 656
 657                                         /* Look for block corruption */
 658                                         if (!jbd2_block_tag_csum_verify(
 659                                                 journal, tag, obh->b_data,
 660                                                 be32_to_cpu(tmp->h_sequence))) {
 661                                                 brelse(obh);
 662                                                 success = -EFSBADCRC;
 663                                                 printk(KERN_ERR "JBD2: Invalid "
 664                                                        "checksum recovering "
 665                                                        "data block %llu in "
 666                                                        "log\n", blocknr);
 667                                                 block_error = 1;
 668                                                 goto skip_write;
 669                                         }
 670
 671                                         /* Find a buffer for the new
 672                                          * data being restored */
 673                                         nbh = __getblk(journal->j_fs_dev,
 674                                                         blocknr,
 675                                                         journal->j_blocksize);
 676                                         if (nbh == NULL) {
 677                                                 printk(KERN_ERR
 678                                                        "JBD2: Out of memory "
 679                                                        "during recovery.\n");
 680                                                 err = -ENOMEM;
 681                                                 brelse(bh);
 682                                                 brelse(obh);
 683                                                 goto failed;
 684                                         }
 685
 686                                         lock_buffer(nbh);
 687                                         memcpy(nbh->b_data, obh->b_data,
 688                                                         journal->j_blocksize);
 689                                         if (flags & JBD2_FLAG_ESCAPE) {
 690                                                 *((__be32 *)nbh->b_data) =
 691                                                 cpu_to_be32(JBD2_MAGIC_NUMBER);
 692                                         }
 693
 694                                         BUFFER_TRACE(nbh, "marking dirty");
 695                                         set_buffer_uptodate(nbh);
 696                                         mark_buffer_dirty(nbh);
 697                                         BUFFER_TRACE(nbh, "marking uptodate");
 698                                         ++info->nr_replays;
 699                                         /* ll_rw_block(WRITE, 1, &nbh); */
 700                                         unlock_buffer(nbh);
 701                                         brelse(obh);
 702                                         brelse(nbh);
 703                                 }
 704
 705                         skip_write:
 706                                 tagp += tag_bytes;
 707                                 if (!(flags & JBD2_FLAG_SAME_UUID))
 708                                         tagp += 16;
 709
 710                                 if (flags & JBD2_FLAG_LAST_TAG)
 711                                         break;
 712                         }
 713
 714                         brelse(bh);
 715                         continue;
 716
 717                 case JBD2_COMMIT_BLOCK:
 718                         /*     How to differentiate between interrupted commit
 719                          *               and journal corruption ?
 720                          *
 721                          * {nth transaction}
 722                          *        Checksum Verification Failed
 723                          *                       |
 724                          *               ____________________
 725                          *              |                    |
 726                          *      async_commit             sync_commit
 727                          *              |                    |
 728                          *              | GO TO NEXT    "Journal Corruption"
 729                          *              | TRANSACTION
 730                          *              |
 731                          * {(n+1)th transanction}
 732                          *              |
 733                          *       _______|______________
 734                          *      |                     |
 735                          * Commit block found   Commit block not found
 736                          *      |                     |
 737                          * "Journal Corruption"       |
 738                          *               _____________|_________
 739                          *              |                       |
 740                          *      nth trans corrupt       OR   nth trans
 741                          *      and (n+1)th interrupted     interrupted
 742                          *      before commit block
 743                          *      could reach the disk.
 744                          *      (Cannot find the difference in above
 745                          *       mentioned conditions. Hence assume
 746                          *       "Interrupted Commit".)
 747                          */
 748                         commit_time = be64_to_cpu(
 749                                 ((struct commit_header *)bh->b_data)->h_commit_sec);
 750                         /*
 751                          * If need_check_commit_time is set, it means we are in
 752                          * PASS_SCAN and csum verify failed before. If
 753                          * commit_time is increasing, it's the same journal,
 754                          * otherwise it is stale journal block, just end this
 755                          * recovery.
 756                          */
 757                         if (need_check_commit_time) {
 758                                 if (commit_time >= last_trans_commit_time) {
 759                                         pr_err("JBD2: Invalid checksum found in transaction %u\n",
 760                                                next_commit_ID);
 761                                         err = -EFSBADCRC;
 762                                         brelse(bh);
 763                                         goto failed;
 764                                 }
 765                         ignore_crc_mismatch:
 766                                 /*
 767                                  * It likely does not belong to same journal,
 768                                  * just end this recovery with success.
 769                                  */
 770                                 jbd_debug(1, "JBD2: Invalid checksum ignored in transaction %u, likely stale data\n",
 771                                           next_commit_ID);
 772                                 err = 0;
 773                                 brelse(bh);
 774                                 goto done;
 775                         }
 776
 777                         /*
 778                          * Found an expected commit block: if checksums
 779                          * are present, verify them in PASS_SCAN; else not
 780                          * much to do other than move on to the next sequence
 781                          * number.
 782                          */
 783                         if (pass == PASS_SCAN &&
 784                             jbd2_has_feature_checksum(journal)) {
 785                                 struct commit_header *cbh =
 786                                         (struct commit_header *)bh->b_data;
 787                                 unsigned found_chksum =
 788                                         be32_to_cpu(cbh->h_chksum[0]);
 789
 790                                 if (info->end_transaction) {
 791                                         journal->j_failed_commit =
 792                                                 info->end_transaction;
 793                                         brelse(bh);
 794                                         break;
 795                                 }
 796
 797                                 /* Neither checksum match nor unused? */
 798                                 if (!((crc32_sum == found_chksum &&
 799                                        cbh->h_chksum_type ==
 800                                                 JBD2_CRC32_CHKSUM &&
 801                                        cbh->h_chksum_size ==
 802                                                 JBD2_CRC32_CHKSUM_SIZE) ||
 803                                       (cbh->h_chksum_type == 0 &&
 804                                        cbh->h_chksum_size == 0 &&
 805                                        found_chksum == 0)))
 806                                         goto chksum_error;
 807
 808                                 crc32_sum = ~0;
 809                         }
 810                         if (pass == PASS_SCAN &&
 811                             !jbd2_commit_block_csum_verify(journal,
 812                                                            bh->b_data)) {
 813                         chksum_error:
 814                                 if (commit_time < last_trans_commit_time)
 815                                         goto ignore_crc_mismatch;
 816                                 info->end_transaction = next_commit_ID;
 817
 818                                 if (!jbd2_has_feature_async_commit(journal)) {
 819                                         journal->j_failed_commit =
 820                                                 next_commit_ID;
 821                                         brelse(bh);
 822                                         break;
 823                                 }
 824                         }
 825                         if (pass == PASS_SCAN)
 826                                 last_trans_commit_time = commit_time;
 827                         brelse(bh);
 828                         next_commit_ID++;
 829                         continue;
 830
 831                 case JBD2_REVOKE_BLOCK:
 832                         /*
 833                          * Check revoke block crc in pass_scan, if csum verify
 834                          * failed, check commit block time later.
 835                          */
 836                         if (pass == PASS_SCAN &&
 837                             !jbd2_descriptor_block_csum_verify(journal,
 838                                                                bh->b_data)) {
 839                                 jbd_debug(1, "JBD2: invalid revoke block found in %lu\n",
 840                                           next_log_block);
 841                                 need_check_commit_time = true;
 842                         }
 843                         /* If we aren't in the REVOKE pass, then we can
 844                          * just skip over this block. */
 845                         if (pass != PASS_REVOKE) {
 846                                 brelse(bh);
 847                                 continue;
 848                         }
 849
 850                         err = scan_revoke_records(journal, bh,
 851                                                   next_commit_ID, info);
 852                         brelse(bh);
 853                         if (err)
 854                                 goto failed;
 855                         continue;
 856
 857                 default:
 858                         jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
 859                                   blocktype);
 860                         brelse(bh);
 861                         goto done;
 862                 }
 863         }
 864
 865  done:
 866         /*
 867          * We broke out of the log scan loop: either we came to the
 868          * known end of the log or we found an unexpected block in the
 869          * log.  If the latter happened, then we know that the "current"
 870          * transaction marks the end of the valid log.
 871          */
 872
 873         if (pass == PASS_SCAN) {
 874                 if (!info->end_transaction)
 875                         info->end_transaction = next_commit_ID;
 876         } else {
 877                 /* It's really bad news if different passes end up at
 878                  * different places (but possible due to IO errors). */
 879                 if (info->end_transaction != next_commit_ID) {
 880                         printk(KERN_ERR "JBD2: recovery pass %d ended at "
 881                                 "transaction %u, expected %u\n",
 882                                 pass, next_commit_ID, info->end_transaction);
 883                         if (!success)
 884                                 success = -EIO;
 885                 }
 886         }
 887
 888         if (jbd2_has_feature_fast_commit(journal) &&  pass != PASS_REVOKE) {
 889                 err = fc_do_one_pass(journal, info, pass);
 890                 if (err)
 891                         success = err;
 892         }
 893
 894         if (block_error && success == 0)
 895                 success = -EIO;
 896         return success;
 897
 898  failed:
 899         return err;
 900 }
 901
 902 /* Scan a revoke record, marking all blocks mentioned as revoked. */
 903
 904 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
 905                                tid_t sequence, struct recovery_info *info)
 906 {
 907         jbd2_journal_revoke_header_t *header;
 908         int offset, max;
 909         int csum_size = 0;
 910         __u32 rcount;
 911         int record_len = 4;
 912
 913         header = (jbd2_journal_revoke_header_t *) bh->b_data;
 914         offset = sizeof(jbd2_journal_revoke_header_t);
 915         rcount = be32_to_cpu(header->r_count);
 916
 917         if (jbd2_journal_has_csum_v2or3(journal))
 918                 csum_size = sizeof(struct jbd2_journal_block_tail);
 919         if (rcount > journal->j_blocksize - csum_size)
 920                 return -EINVAL;
 921         max = rcount;
 922
 923         if (jbd2_has_feature_64bit(journal))
 924                 record_len = 8;
 925
 926         while (offset + record_len <= max) {
 927                 unsigned long long blocknr;
 928                 int err;
 929
 930                 if (record_len == 4)
 931                         blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
 932                 else
 933                         blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
 934                 offset += record_len;
 935                 err = jbd2_journal_set_revoke(journal, blocknr, sequence);
 936                 if (err)
 937                         return err;
 938                 ++info->nr_revokes;
 939         }
 940         return 0;
 941 }