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 <[email protected]>, 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         unsigned long   head_block;
  33
  34         int             nr_replays;
  35         int             nr_revokes;
  36         int             nr_revoke_hits;
  37 };
  38
  39 static int do_one_pass(journal_t *journal,
  40                                 struct recovery_info *info, enum passtype pass);
  41 static int scan_revoke_records(journal_t *, struct buffer_head *,
  42                                 tid_t, struct recovery_info *);
  43
  44 #ifdef __KERNEL__
  45
  46 /* Release readahead buffers after use */
  47 static void journal_brelse_array(struct buffer_head *b[], int n)
  48 {
  49         while (--n >= 0)
  50                 brelse (b[n]);
  51 }
  52
  53
  54 /*
  55  * When reading from the journal, we are going through the block device
  56  * layer directly and so there is no readahead being done for us.  We
  57  * need to implement any readahead ourselves if we want it to happen at
  58  * all.  Recovery is basically one long sequential read, so make sure we
  59  * do the IO in reasonably large chunks.
  60  *
  61  * This is not so critical that we need to be enormously clever about
  62  * the readahead size, though.  128K is a purely arbitrary, good-enough
  63  * fixed value.
  64  */
  65
  66 #define MAXBUF 8
  67 static int do_readahead(journal_t *journal, unsigned int start)
  68 {
  69         int err;
  70         unsigned int max, nbufs, next;
  71         unsigned long long blocknr;
  72         struct buffer_head *bh;
  73
  74         struct buffer_head * bufs[MAXBUF];
  75
  76         /* Do up to 128K of readahead */
  77         max = start + (128 * 1024 / journal->j_blocksize);
  78         if (max > journal->j_total_len)
  79                 max = journal->j_total_len;
  80
  81         /* Do the readahead itself.  We'll submit MAXBUF buffer_heads at
  82          * a time to the block device IO layer. */
  83
  84         nbufs = 0;
  85
  86         for (next = start; next < max; next++) {
  87                 err = jbd2_journal_bmap(journal, next, &blocknr);
  88
  89                 if (err) {
  90                         printk(KERN_ERR "JBD2: bad block at offset %u\n",
  91                                 next);
  92                         goto failed;
  93                 }
  94
  95                 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
  96                 if (!bh) {
  97                         err = -ENOMEM;
  98                         goto failed;
  99                 }
 100
 101                 if (!buffer_uptodate(bh) && !buffer_locked(bh)) {
 102                         bufs[nbufs++] = bh;
 103                         if (nbufs == MAXBUF) {
 104                                 bh_readahead_batch(nbufs, bufs, 0);
 105                                 journal_brelse_array(bufs, nbufs);
 106                                 nbufs = 0;
 107                         }
 108                 } else
 109                         brelse(bh);
 110         }
 111
 112         if (nbufs)
 113                 bh_readahead_batch(nbufs, bufs, 0);
 114         err = 0;
 115
 116 failed:
 117         if (nbufs)
 118                 journal_brelse_array(bufs, nbufs);
 119         return err;
 120 }
 121
 122 #endif /* __KERNEL__ */
 123
 124
 125 /*
 126  * Read a block from the journal
 127  */
 128
 129 static int jread(struct buffer_head **bhp, journal_t *journal,
 130                  unsigned int offset)
 131 {
 132         int err;
 133         unsigned long long blocknr;
 134         struct buffer_head *bh;
 135
 136         *bhp = NULL;
 137
 138         if (offset >= journal->j_total_len) {
 139                 printk(KERN_ERR "JBD2: corrupted journal superblock\n");
 140                 return -EFSCORRUPTED;
 141         }
 142
 143         err = jbd2_journal_bmap(journal, offset, &blocknr);
 144
 145         if (err) {
 146                 printk(KERN_ERR "JBD2: bad block at offset %u\n",
 147                         offset);
 148                 return err;
 149         }
 150
 151         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
 152         if (!bh)
 153                 return -ENOMEM;
 154
 155         if (!buffer_uptodate(bh)) {
 156                 /*
 157                  * If this is a brand new buffer, start readahead.
 158                  * Otherwise, we assume we are already reading it.
 159                  */
 160                 bool need_readahead = !buffer_req(bh);
 161
 162                 bh_read_nowait(bh, 0);
 163                 if (need_readahead)
 164                         do_readahead(journal, offset);
 165                 wait_on_buffer(bh);
 166         }
 167
 168         if (!buffer_uptodate(bh)) {
 169                 printk(KERN_ERR "JBD2: Failed to read block at offset %u\n",
 170                         offset);
 171                 brelse(bh);
 172                 return -EIO;
 173         }
 174
 175         *bhp = bh;
 176         return 0;
 177 }
 178
 179 static int jbd2_descriptor_block_csum_verify(journal_t *j, void *buf)
 180 {
 181         struct jbd2_journal_block_tail *tail;
 182         __be32 provided;
 183         __u32 calculated;
 184
 185         if (!jbd2_journal_has_csum_v2or3(j))
 186                 return 1;
 187
 188         tail = (struct jbd2_journal_block_tail *)((char *)buf +
 189                 j->j_blocksize - sizeof(struct jbd2_journal_block_tail));
 190         provided = tail->t_checksum;
 191         tail->t_checksum = 0;
 192         calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 193         tail->t_checksum = provided;
 194
 195         return provided == cpu_to_be32(calculated);
 196 }
 197
 198 /*
 199  * Count the number of in-use tags in a journal descriptor block.
 200  */
 201
 202 static int count_tags(journal_t *journal, struct buffer_head *bh)
 203 {
 204         char *                  tagp;
 205         journal_block_tag_t     tag;
 206         int                     nr = 0, size = journal->j_blocksize;
 207         int                     tag_bytes = journal_tag_bytes(journal);
 208
 209         if (jbd2_journal_has_csum_v2or3(journal))
 210                 size -= sizeof(struct jbd2_journal_block_tail);
 211
 212         tagp = &bh->b_data[sizeof(journal_header_t)];
 213
 214         while ((tagp - bh->b_data + tag_bytes) <= size) {
 215                 memcpy(&tag, tagp, sizeof(tag));
 216
 217                 nr++;
 218                 tagp += tag_bytes;
 219                 if (!(tag.t_flags & cpu_to_be16(JBD2_FLAG_SAME_UUID)))
 220                         tagp += 16;
 221
 222                 if (tag.t_flags & cpu_to_be16(JBD2_FLAG_LAST_TAG))
 223                         break;
 224         }
 225
 226         return nr;
 227 }
 228
 229
 230 /* Make sure we wrap around the log correctly! */
 231 #define wrap(journal, var)                                              \
 232 do {                                                                    \
 233         if (var >= (journal)->j_last)                                   \
 234                 var -= ((journal)->j_last - (journal)->j_first);        \
 235 } while (0)
 236
 237 static int fc_do_one_pass(journal_t *journal,
 238                           struct recovery_info *info, enum passtype pass)
 239 {
 240         unsigned int expected_commit_id = info->end_transaction;
 241         unsigned long next_fc_block;
 242         struct buffer_head *bh;
 243         int err = 0;
 244
 245         next_fc_block = journal->j_fc_first;
 246         if (!journal->j_fc_replay_callback)
 247                 return 0;
 248
 249         while (next_fc_block <= journal->j_fc_last) {
 250                 jbd2_debug(3, "Fast commit replay: next block %ld\n",
 251                           next_fc_block);
 252                 err = jread(&bh, journal, next_fc_block);
 253                 if (err) {
 254                         jbd2_debug(3, "Fast commit replay: read error\n");
 255                         break;
 256                 }
 257
 258                 err = journal->j_fc_replay_callback(journal, bh, pass,
 259                                         next_fc_block - journal->j_fc_first,
 260                                         expected_commit_id);
 261                 brelse(bh);
 262                 next_fc_block++;
 263                 if (err < 0 || err == JBD2_FC_REPLAY_STOP)
 264                         break;
 265                 err = 0;
 266         }
 267
 268         if (err)
 269                 jbd2_debug(3, "Fast commit replay failed, err = %d\n", err);
 270
 271         return err;
 272 }
 273
 274 /**
 275  * jbd2_journal_recover - recovers a on-disk journal
 276  * @journal: the journal to recover
 277  *
 278  * The primary function for recovering the log contents when mounting a
 279  * journaled device.
 280  *
 281  * Recovery is done in three passes.  In the first pass, we look for the
 282  * end of the log.  In the second, we assemble the list of revoke
 283  * blocks.  In the third and final pass, we replay any un-revoked blocks
 284  * in the log.
 285  */
 286 int jbd2_journal_recover(journal_t *journal)
 287 {
 288         int                     err, err2;
 289         journal_superblock_t *  sb;
 290
 291         struct recovery_info    info;
 292         errseq_t                wb_err;
 293         struct address_space    *mapping;
 294
 295         memset(&info, 0, sizeof(info));
 296         sb = journal->j_superblock;
 297
 298         /*
 299          * The journal superblock's s_start field (the current log head)
 300          * is always zero if, and only if, the journal was cleanly
 301          * unmounted.
 302          */
 303         if (!sb->s_start) {
 304                 jbd2_debug(1, "No recovery required, last transaction %d, head block %u\n",
 305                           be32_to_cpu(sb->s_sequence), be32_to_cpu(sb->s_head));
 306                 journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
 307                 journal->j_head = be32_to_cpu(sb->s_head);
 308                 return 0;
 309         }
 310
 311         wb_err = 0;
 312         mapping = journal->j_fs_dev->bd_inode->i_mapping;
 313         errseq_check_and_advance(&mapping->wb_err, &wb_err);
 314         err = do_one_pass(journal, &info, PASS_SCAN);
 315         if (!err)
 316                 err = do_one_pass(journal, &info, PASS_REVOKE);
 317         if (!err)
 318                 err = do_one_pass(journal, &info, PASS_REPLAY);
 319
 320         jbd2_debug(1, "JBD2: recovery, exit status %d, "
 321                   "recovered transactions %u to %u\n",
 322                   err, info.start_transaction, info.end_transaction);
 323         jbd2_debug(1, "JBD2: Replayed %d and revoked %d/%d blocks\n",
 324                   info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
 325
 326         /* Restart the log at the next transaction ID, thus invalidating
 327          * any existing commit records in the log. */
 328         journal->j_transaction_sequence = ++info.end_transaction;
 329         journal->j_head = info.head_block;
 330         jbd2_debug(1, "JBD2: last transaction %d, head block %lu\n",
 331                   journal->j_transaction_sequence, journal->j_head);
 332
 333         jbd2_journal_clear_revoke(journal);
 334         err2 = sync_blockdev(journal->j_fs_dev);
 335         if (!err)
 336                 err = err2;
 337         err2 = errseq_check_and_advance(&mapping->wb_err, &wb_err);
 338         if (!err)
 339                 err = err2;
 340         /* Make sure all replayed data is on permanent storage */
 341         if (journal->j_flags & JBD2_BARRIER) {
 342                 err2 = blkdev_issue_flush(journal->j_fs_dev);
 343                 if (!err)
 344                         err = err2;
 345         }
 346         return err;
 347 }
 348
 349 /**
 350  * jbd2_journal_skip_recovery - Start journal and wipe exiting records
 351  * @journal: journal to startup
 352  *
 353  * Locate any valid recovery information from the journal and set up the
 354  * journal structures in memory to ignore it (presumably because the
 355  * caller has evidence that it is out of date).
 356  * This function doesn't appear to be exported..
 357  *
 358  * We perform one pass over the journal to allow us to tell the user how
 359  * much recovery information is being erased, and to let us initialise
 360  * the journal transaction sequence numbers to the next unused ID.
 361  */
 362 int jbd2_journal_skip_recovery(journal_t *journal)
 363 {
 364         int                     err;
 365
 366         struct recovery_info    info;
 367
 368         memset (&info, 0, sizeof(info));
 369
 370         err = do_one_pass(journal, &info, PASS_SCAN);
 371
 372         if (err) {
 373                 printk(KERN_ERR "JBD2: error %d scanning journal\n", err);
 374                 ++journal->j_transaction_sequence;
 375                 journal->j_head = journal->j_first;
 376         } else {
 377 #ifdef CONFIG_JBD2_DEBUG
 378                 int dropped = info.end_transaction -
 379                         be32_to_cpu(journal->j_superblock->s_sequence);
 380                 jbd2_debug(1,
 381                           "JBD2: ignoring %d transaction%s from the journal.\n",
 382                           dropped, (dropped == 1) ? "" : "s");
 383 #endif
 384                 journal->j_transaction_sequence = ++info.end_transaction;
 385                 journal->j_head = info.head_block;
 386         }
 387
 388         journal->j_tail = 0;
 389         return err;
 390 }
 391
 392 static inline unsigned long long read_tag_block(journal_t *journal,
 393                                                 journal_block_tag_t *tag)
 394 {
 395         unsigned long long block = be32_to_cpu(tag->t_blocknr);
 396         if (jbd2_has_feature_64bit(journal))
 397                 block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
 398         return block;
 399 }
 400
 401 /*
 402  * calc_chksums calculates the checksums for the blocks described in the
 403  * descriptor block.
 404  */
 405 static int calc_chksums(journal_t *journal, struct buffer_head *bh,
 406                         unsigned long *next_log_block, __u32 *crc32_sum)
 407 {
 408         int i, num_blks, err;
 409         unsigned long io_block;
 410         struct buffer_head *obh;
 411
 412         num_blks = count_tags(journal, bh);
 413         /* Calculate checksum of the descriptor block. */
 414         *crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
 415
 416         for (i = 0; i < num_blks; i++) {
 417                 io_block = (*next_log_block)++;
 418                 wrap(journal, *next_log_block);
 419                 err = jread(&obh, journal, io_block);
 420                 if (err) {
 421                         printk(KERN_ERR "JBD2: IO error %d recovering block "
 422                                 "%lu in log\n", err, io_block);
 423                         return 1;
 424                 } else {
 425                         *crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
 426                                      obh->b_size);
 427                 }
 428                 put_bh(obh);
 429         }
 430         return 0;
 431 }
 432
 433 static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
 434 {
 435         struct commit_header *h;
 436         __be32 provided;
 437         __u32 calculated;
 438
 439         if (!jbd2_journal_has_csum_v2or3(j))
 440                 return 1;
 441
 442         h = buf;
 443         provided = h->h_chksum[0];
 444         h->h_chksum[0] = 0;
 445         calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 446         h->h_chksum[0] = provided;
 447
 448         return provided == cpu_to_be32(calculated);
 449 }
 450
 451 static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
 452                                       journal_block_tag3_t *tag3,
 453                                       void *buf, __u32 sequence)
 454 {
 455         __u32 csum32;
 456         __be32 seq;
 457
 458         if (!jbd2_journal_has_csum_v2or3(j))
 459                 return 1;
 460
 461         seq = cpu_to_be32(sequence);
 462         csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
 463         csum32 = jbd2_chksum(j, csum32, buf, j->j_blocksize);
 464
 465         if (jbd2_has_feature_csum3(j))
 466                 return tag3->t_checksum == cpu_to_be32(csum32);
 467         else
 468                 return tag->t_checksum == cpu_to_be16(csum32);
 469 }
 470
 471 static int do_one_pass(journal_t *journal,
 472                         struct recovery_info *info, enum passtype pass)
 473 {
 474         unsigned int            first_commit_ID, next_commit_ID;
 475         unsigned long           next_log_block, head_block;
 476         int                     err, success = 0;
 477         journal_superblock_t *  sb;
 478         journal_header_t *      tmp;
 479         struct buffer_head *    bh;
 480         unsigned int            sequence;
 481         int                     blocktype;
 482         int                     tag_bytes = journal_tag_bytes(journal);
 483         __u32                   crc32_sum = ~0; /* Transactional Checksums */
 484         int                     descr_csum_size = 0;
 485         int                     block_error = 0;
 486         bool                    need_check_commit_time = false;
 487         __u64                   last_trans_commit_time = 0, commit_time;
 488
 489         /*
 490          * First thing is to establish what we expect to find in the log
 491          * (in terms of transaction IDs), and where (in terms of log
 492          * block offsets): query the superblock.
 493          */
 494
 495         sb = journal->j_superblock;
 496         next_commit_ID = be32_to_cpu(sb->s_sequence);
 497         next_log_block = be32_to_cpu(sb->s_start);
 498         head_block = next_log_block;
 499
 500         first_commit_ID = next_commit_ID;
 501         if (pass == PASS_SCAN)
 502                 info->start_transaction = first_commit_ID;
 503
 504         jbd2_debug(1, "Starting recovery pass %d\n", pass);
 505
 506         /*
 507          * Now we walk through the log, transaction by transaction,
 508          * making sure that each transaction has a commit block in the
 509          * expected place.  Each complete transaction gets replayed back
 510          * into the main filesystem.
 511          */
 512
 513         while (1) {
 514                 int                     flags;
 515                 char *                  tagp;
 516                 journal_block_tag_t     tag;
 517                 struct buffer_head *    obh;
 518                 struct buffer_head *    nbh;
 519
 520                 cond_resched();
 521
 522                 /* If we already know where to stop the log traversal,
 523                  * check right now that we haven't gone past the end of
 524                  * the log. */
 525
 526                 if (pass != PASS_SCAN)
 527                         if (tid_geq(next_commit_ID, info->end_transaction))
 528                                 break;
 529
 530                 jbd2_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
 531                           next_commit_ID, next_log_block, journal->j_last);
 532
 533                 /* Skip over each chunk of the transaction looking
 534                  * either the next descriptor block or the final commit
 535                  * record. */
 536
 537                 jbd2_debug(3, "JBD2: checking block %ld\n", next_log_block);
 538                 err = jread(&bh, journal, next_log_block);
 539                 if (err)
 540                         goto failed;
 541
 542                 next_log_block++;
 543                 wrap(journal, next_log_block);
 544
 545                 /* What kind of buffer is it?
 546                  *
 547                  * If it is a descriptor block, check that it has the
 548                  * expected sequence number.  Otherwise, we're all done
 549                  * here. */
 550
 551                 tmp = (journal_header_t *)bh->b_data;
 552
 553                 if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
 554                         brelse(bh);
 555                         break;
 556                 }
 557
 558                 blocktype = be32_to_cpu(tmp->h_blocktype);
 559                 sequence = be32_to_cpu(tmp->h_sequence);
 560                 jbd2_debug(3, "Found magic %d, sequence %d\n",
 561                           blocktype, sequence);
 562
 563                 if (sequence != next_commit_ID) {
 564                         brelse(bh);
 565                         break;
 566                 }
 567
 568                 /* OK, we have a valid descriptor block which matches
 569                  * all of the sequence number checks.  What are we going
 570                  * to do with it?  That depends on the pass... */
 571
 572                 switch(blocktype) {
 573                 case JBD2_DESCRIPTOR_BLOCK:
 574                         /* Verify checksum first */
 575                         if (jbd2_journal_has_csum_v2or3(journal))
 576                                 descr_csum_size =
 577                                         sizeof(struct jbd2_journal_block_tail);
 578                         if (descr_csum_size > 0 &&
 579                             !jbd2_descriptor_block_csum_verify(journal,
 580                                                                bh->b_data)) {
 581                                 /*
 582                                  * PASS_SCAN can see stale blocks due to lazy
 583                                  * journal init. Don't error out on those yet.
 584                                  */
 585                                 if (pass != PASS_SCAN) {
 586                                         pr_err("JBD2: Invalid checksum recovering block %lu in log\n",
 587                                                next_log_block);
 588                                         err = -EFSBADCRC;
 589                                         brelse(bh);
 590                                         goto failed;
 591                                 }
 592                                 need_check_commit_time = true;
 593                                 jbd2_debug(1,
 594                                         "invalid descriptor block found in %lu\n",
 595                                         next_log_block);
 596                         }
 597
 598                         /* If it is a valid descriptor block, replay it
 599                          * in pass REPLAY; if journal_checksums enabled, then
 600                          * calculate checksums in PASS_SCAN, otherwise,
 601                          * just skip over the blocks it describes. */
 602                         if (pass != PASS_REPLAY) {
 603                                 if (pass == PASS_SCAN &&
 604                                     jbd2_has_feature_checksum(journal) &&
 605                                     !need_check_commit_time &&
 606                                     !info->end_transaction) {
 607                                         if (calc_chksums(journal, bh,
 608                                                         &next_log_block,
 609                                                         &crc32_sum)) {
 610                                                 put_bh(bh);
 611                                                 break;
 612                                         }
 613                                         put_bh(bh);
 614                                         continue;
 615                                 }
 616                                 next_log_block += count_tags(journal, bh);
 617                                 wrap(journal, next_log_block);
 618                                 put_bh(bh);
 619                                 continue;
 620                         }
 621
 622                         /* A descriptor block: we can now write all of
 623                          * the data blocks.  Yay, useful work is finally
 624                          * getting done here! */
 625
 626                         tagp = &bh->b_data[sizeof(journal_header_t)];
 627                         while ((tagp - bh->b_data + tag_bytes)
 628                                <= journal->j_blocksize - descr_csum_size) {
 629                                 unsigned long io_block;
 630
 631                                 memcpy(&tag, tagp, sizeof(tag));
 632                                 flags = be16_to_cpu(tag.t_flags);
 633
 634                                 io_block = next_log_block++;
 635                                 wrap(journal, next_log_block);
 636                                 err = jread(&obh, journal, io_block);
 637                                 if (err) {
 638                                         /* Recover what we can, but
 639                                          * report failure at the end. */
 640                                         success = err;
 641                                         printk(KERN_ERR
 642                                                 "JBD2: IO error %d recovering "
 643                                                 "block %lu in log\n",
 644                                                 err, io_block);
 645                                 } else {
 646                                         unsigned long long blocknr;
 647
 648                                         J_ASSERT(obh != NULL);
 649                                         blocknr = read_tag_block(journal,
 650                                                                  &tag);
 651
 652                                         /* If the block has been
 653                                          * revoked, then we're all done
 654                                          * here. */
 655                                         if (jbd2_journal_test_revoke
 656                                             (journal, blocknr,
 657                                              next_commit_ID)) {
 658                                                 brelse(obh);
 659                                                 ++info->nr_revoke_hits;
 660                                                 goto skip_write;
 661                                         }
 662
 663                                         /* Look for block corruption */
 664                                         if (!jbd2_block_tag_csum_verify(
 665                         journal, &tag, (journal_block_tag3_t *)tagp,
 666                         obh->b_data, be32_to_cpu(tmp->h_sequence))) {
 667                                                 brelse(obh);
 668                                                 success = -EFSBADCRC;
 669                                                 printk(KERN_ERR "JBD2: Invalid "
 670                                                        "checksum recovering "
 671                                                        "data block %llu in "
 672                                                        "journal block %lu\n",
 673                                                        blocknr, io_block);
 674                                                 block_error = 1;
 675                                                 goto skip_write;
 676                                         }
 677
 678                                         /* Find a buffer for the new
 679                                          * data being restored */
 680                                         nbh = __getblk(journal->j_fs_dev,
 681                                                         blocknr,
 682                                                         journal->j_blocksize);
 683                                         if (nbh == NULL) {
 684                                                 printk(KERN_ERR
 685                                                        "JBD2: Out of memory "
 686                                                        "during recovery.\n");
 687                                                 err = -ENOMEM;
 688                                                 brelse(bh);
 689                                                 brelse(obh);
 690                                                 goto failed;
 691                                         }
 692
 693                                         lock_buffer(nbh);
 694                                         memcpy(nbh->b_data, obh->b_data,
 695                                                         journal->j_blocksize);
 696                                         if (flags & JBD2_FLAG_ESCAPE) {
 697                                                 *((__be32 *)nbh->b_data) =
 698                                                 cpu_to_be32(JBD2_MAGIC_NUMBER);
 699                                         }
 700
 701                                         BUFFER_TRACE(nbh, "marking dirty");
 702                                         set_buffer_uptodate(nbh);
 703                                         mark_buffer_dirty(nbh);
 704                                         BUFFER_TRACE(nbh, "marking uptodate");
 705                                         ++info->nr_replays;
 706                                         unlock_buffer(nbh);
 707                                         brelse(obh);
 708                                         brelse(nbh);
 709                                 }
 710
 711                         skip_write:
 712                                 tagp += tag_bytes;
 713                                 if (!(flags & JBD2_FLAG_SAME_UUID))
 714                                         tagp += 16;
 715
 716                                 if (flags & JBD2_FLAG_LAST_TAG)
 717                                         break;
 718                         }
 719
 720                         brelse(bh);
 721                         continue;
 722
 723                 case JBD2_COMMIT_BLOCK:
 724                         /*     How to differentiate between interrupted commit
 725                          *               and journal corruption ?
 726                          *
 727                          * {nth transaction}
 728                          *        Checksum Verification Failed
 729                          *                       |
 730                          *               ____________________
 731                          *              |                    |
 732                          *      async_commit             sync_commit
 733                          *              |                    |
 734                          *              | GO TO NEXT    "Journal Corruption"
 735                          *              | TRANSACTION
 736                          *              |
 737                          * {(n+1)th transanction}
 738                          *              |
 739                          *       _______|______________
 740                          *      |                     |
 741                          * Commit block found   Commit block not found
 742                          *      |                     |
 743                          * "Journal Corruption"       |
 744                          *               _____________|_________
 745                          *              |                       |
 746                          *      nth trans corrupt       OR   nth trans
 747                          *      and (n+1)th interrupted     interrupted
 748                          *      before commit block
 749                          *      could reach the disk.
 750                          *      (Cannot find the difference in above
 751                          *       mentioned conditions. Hence assume
 752                          *       "Interrupted Commit".)
 753                          */
 754                         commit_time = be64_to_cpu(
 755                                 ((struct commit_header *)bh->b_data)->h_commit_sec);
 756                         /*
 757                          * If need_check_commit_time is set, it means we are in
 758                          * PASS_SCAN and csum verify failed before. If
 759                          * commit_time is increasing, it's the same journal,
 760                          * otherwise it is stale journal block, just end this
 761                          * recovery.
 762                          */
 763                         if (need_check_commit_time) {
 764                                 if (commit_time >= last_trans_commit_time) {
 765                                         pr_err("JBD2: Invalid checksum found in transaction %u\n",
 766                                                next_commit_ID);
 767                                         err = -EFSBADCRC;
 768                                         brelse(bh);
 769                                         goto failed;
 770                                 }
 771                         ignore_crc_mismatch:
 772                                 /*
 773                                  * It likely does not belong to same journal,
 774                                  * just end this recovery with success.
 775                                  */
 776                                 jbd2_debug(1, "JBD2: Invalid checksum ignored in transaction %u, likely stale data\n",
 777                                           next_commit_ID);
 778                                 brelse(bh);
 779                                 goto done;
 780                         }
 781
 782                         /*
 783                          * Found an expected commit block: if checksums
 784                          * are present, verify them in PASS_SCAN; else not
 785                          * much to do other than move on to the next sequence
 786                          * number.
 787                          */
 788                         if (pass == PASS_SCAN &&
 789                             jbd2_has_feature_checksum(journal)) {
 790                                 struct commit_header *cbh =
 791                                         (struct commit_header *)bh->b_data;
 792                                 unsigned found_chksum =
 793                                         be32_to_cpu(cbh->h_chksum[0]);
 794
 795                                 if (info->end_transaction) {
 796                                         journal->j_failed_commit =
 797                                                 info->end_transaction;
 798                                         brelse(bh);
 799                                         break;
 800                                 }
 801
 802                                 /* Neither checksum match nor unused? */
 803                                 if (!((crc32_sum == found_chksum &&
 804                                        cbh->h_chksum_type ==
 805                                                 JBD2_CRC32_CHKSUM &&
 806                                        cbh->h_chksum_size ==
 807                                                 JBD2_CRC32_CHKSUM_SIZE) ||
 808                                       (cbh->h_chksum_type == 0 &&
 809                                        cbh->h_chksum_size == 0 &&
 810                                        found_chksum == 0)))
 811                                         goto chksum_error;
 812
 813                                 crc32_sum = ~0;
 814                         }
 815                         if (pass == PASS_SCAN &&
 816                             !jbd2_commit_block_csum_verify(journal,
 817                                                            bh->b_data)) {
 818                         chksum_error:
 819                                 if (commit_time < last_trans_commit_time)
 820                                         goto ignore_crc_mismatch;
 821                                 info->end_transaction = next_commit_ID;
 822                                 info->head_block = head_block;
 823
 824                                 if (!jbd2_has_feature_async_commit(journal)) {
 825                                         journal->j_failed_commit =
 826                                                 next_commit_ID;
 827                                         brelse(bh);
 828                                         break;
 829                                 }
 830                         }
 831                         if (pass == PASS_SCAN) {
 832                                 last_trans_commit_time = commit_time;
 833                                 head_block = next_log_block;
 834                         }
 835                         brelse(bh);
 836                         next_commit_ID++;
 837                         continue;
 838
 839                 case JBD2_REVOKE_BLOCK:
 840                         /*
 841                          * Check revoke block crc in pass_scan, if csum verify
 842                          * failed, check commit block time later.
 843                          */
 844                         if (pass == PASS_SCAN &&
 845                             !jbd2_descriptor_block_csum_verify(journal,
 846                                                                bh->b_data)) {
 847                                 jbd2_debug(1, "JBD2: invalid revoke block found in %lu\n",
 848                                           next_log_block);
 849                                 need_check_commit_time = true;
 850                         }
 851                         /* If we aren't in the REVOKE pass, then we can
 852                          * just skip over this block. */
 853                         if (pass != PASS_REVOKE) {
 854                                 brelse(bh);
 855                                 continue;
 856                         }
 857
 858                         err = scan_revoke_records(journal, bh,
 859                                                   next_commit_ID, info);
 860                         brelse(bh);
 861                         if (err)
 862                                 goto failed;
 863                         continue;
 864
 865                 default:
 866                         jbd2_debug(3, "Unrecognised magic %d, end of scan.\n",
 867                                   blocktype);
 868                         brelse(bh);
 869                         goto done;
 870                 }
 871         }
 872
 873  done:
 874         /*
 875          * We broke out of the log scan loop: either we came to the
 876          * known end of the log or we found an unexpected block in the
 877          * log.  If the latter happened, then we know that the "current"
 878          * transaction marks the end of the valid log.
 879          */
 880
 881         if (pass == PASS_SCAN) {
 882                 if (!info->end_transaction)
 883                         info->end_transaction = next_commit_ID;
 884                 if (!info->head_block)
 885                         info->head_block = head_block;
 886         } else {
 887                 /* It's really bad news if different passes end up at
 888                  * different places (but possible due to IO errors). */
 889                 if (info->end_transaction != next_commit_ID) {
 890                         printk(KERN_ERR "JBD2: recovery pass %d ended at "
 891                                 "transaction %u, expected %u\n",
 892                                 pass, next_commit_ID, info->end_transaction);
 893                         if (!success)
 894                                 success = -EIO;
 895                 }
 896         }
 897
 898         if (jbd2_has_feature_fast_commit(journal) &&  pass != PASS_REVOKE) {
 899                 err = fc_do_one_pass(journal, info, pass);
 900                 if (err)
 901                         success = err;
 902         }
 903
 904         if (block_error && success == 0)
 905                 success = -EIO;
 906         return success;
 907
 908  failed:
 909         return err;
 910 }
 911
 912 /* Scan a revoke record, marking all blocks mentioned as revoked. */
 913
 914 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
 915                                tid_t sequence, struct recovery_info *info)
 916 {
 917         jbd2_journal_revoke_header_t *header;
 918         int offset, max;
 919         unsigned csum_size = 0;
 920         __u32 rcount;
 921         int record_len = 4;
 922
 923         header = (jbd2_journal_revoke_header_t *) bh->b_data;
 924         offset = sizeof(jbd2_journal_revoke_header_t);
 925         rcount = be32_to_cpu(header->r_count);
 926
 927         if (jbd2_journal_has_csum_v2or3(journal))
 928                 csum_size = sizeof(struct jbd2_journal_block_tail);
 929         if (rcount > journal->j_blocksize - csum_size)
 930                 return -EINVAL;
 931         max = rcount;
 932
 933         if (jbd2_has_feature_64bit(journal))
 934                 record_len = 8;
 935
 936         while (offset + record_len <= max) {
 937                 unsigned long long blocknr;
 938                 int err;
 939
 940                 if (record_len == 4)
 941                         blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
 942                 else
 943                         blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
 944                 offset += record_len;
 945                 err = jbd2_journal_set_revoke(journal, blocknr, sequence);
 946                 if (err)
 947                         return err;
 948                 ++info->nr_revokes;
 949         }
 950         return 0;
 951 }