fs/jbd2/recovery.c

   1 /*
   2  * linux/fs/jbd2/recovery.c
   3  *
   4  * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
   5  *
   6  * Copyright 1999-2000 Red Hat Software --- All Rights Reserved
   7  *
   8  * This file is part of the Linux kernel and is made available under
   9  * the terms of the GNU General Public License, version 2, or at your
  10  * option, any later version, incorporated herein by reference.
  11  *
  12  * Journal recovery routines for the generic filesystem journaling code;
  13  * part of the ext2fs journaling system.
  14  */
  15
  16 #ifndef __KERNEL__
  17 #include "jfs_user.h"
  18 #else
  19 #include <linux/time.h>
  20 #include <linux/fs.h>
  21 #include <linux/jbd2.h>
  22 #include <linux/errno.h>
  23 #include <linux/slab.h>
  24 #endif
  25
  26 /*
  27  * Maintain information about the progress of the recovery job, so that
  28  * the different passes can carry information between them.
  29  */
  30 struct recovery_info
  31 {
  32         tid_t           start_transaction;
  33         tid_t           end_transaction;
  34
  35         int             nr_replays;
  36         int             nr_revokes;
  37         int             nr_revoke_hits;
  38 };
  39
  40 enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY};
  41 static int do_one_pass(journal_t *journal,
  42                                 struct recovery_info *info, enum passtype pass);
  43 static int scan_revoke_records(journal_t *, struct buffer_head *,
  44                                 tid_t, struct recovery_info *);
  45
  46 #ifdef __KERNEL__
  47
  48 /* Release readahead buffers after use */
  49 static void journal_brelse_array(struct buffer_head *b[], int n)
  50 {
  51         while (--n >= 0)
  52                 brelse (b[n]);
  53 }
  54
  55
  56 /*
  57  * When reading from the journal, we are going through the block device
  58  * layer directly and so there is no readahead being done for us.  We
  59  * need to implement any readahead ourselves if we want it to happen at
  60  * all.  Recovery is basically one long sequential read, so make sure we
  61  * do the IO in reasonably large chunks.
  62  *
  63  * This is not so critical that we need to be enormously clever about
  64  * the readahead size, though.  128K is a purely arbitrary, good-enough
  65  * fixed value.
  66  */
  67
  68 #define MAXBUF 8
  69 static int do_readahead(journal_t *journal, unsigned int start)
  70 {
  71         int err;
  72         unsigned int max, nbufs, next;
  73         unsigned long long blocknr;
  74         struct buffer_head *bh;
  75
  76         struct buffer_head * bufs[MAXBUF];
  77
  78         /* Do up to 128K of readahead */
  79         max = start + (128 * 1024 / journal->j_blocksize);
  80         if (max > journal->j_maxlen)
  81                 max = journal->j_maxlen;
  82
  83         /* Do the readahead itself.  We'll submit MAXBUF buffer_heads at
  84          * a time to the block device IO layer. */
  85
  86         nbufs = 0;
  87
  88         for (next = start; next < max; next++) {
  89                 err = jbd2_journal_bmap(journal, next, &blocknr);
  90
  91                 if (err) {
  92                         printk (KERN_ERR "JBD: bad block at offset %u\n",
  93                                 next);
  94                         goto failed;
  95                 }
  96
  97                 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
  98                 if (!bh) {
  99                         err = -ENOMEM;
 100                         goto failed;
 101                 }
 102
 103                 if (!buffer_uptodate(bh) && !buffer_locked(bh)) {
 104                         bufs[nbufs++] = bh;
 105                         if (nbufs == MAXBUF) {
 106                                 ll_rw_block(READ, nbufs, bufs);
 107                                 journal_brelse_array(bufs, nbufs);
 108                                 nbufs = 0;
 109                         }
 110                 } else
 111                         brelse(bh);
 112         }
 113
 114         if (nbufs)
 115                 ll_rw_block(READ, nbufs, bufs);
 116         err = 0;
 117
 118 failed:
 119         if (nbufs)
 120                 journal_brelse_array(bufs, nbufs);
 121         return err;
 122 }
 123
 124 #endif /* __KERNEL__ */
 125
 126
 127 /*
 128  * Read a block from the journal
 129  */
 130
 131 static int jread(struct buffer_head **bhp, journal_t *journal,
 132                  unsigned int offset)
 133 {
 134         int err;
 135         unsigned long long blocknr;
 136         struct buffer_head *bh;
 137
 138         *bhp = NULL;
 139
 140         if (offset >= journal->j_maxlen) {
 141                 printk(KERN_ERR "JBD: corrupted journal superblock\n");
 142                 return -EIO;
 143         }
 144
 145         err = jbd2_journal_bmap(journal, offset, &blocknr);
 146
 147         if (err) {
 148                 printk (KERN_ERR "JBD: bad block at offset %u\n",
 149                         offset);
 150                 return err;
 151         }
 152
 153         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
 154         if (!bh)
 155                 return -ENOMEM;
 156
 157         if (!buffer_uptodate(bh)) {
 158                 /* If this is a brand new buffer, start readahead.
 159                    Otherwise, we assume we are already reading it.  */
 160                 if (!buffer_req(bh))
 161                         do_readahead(journal, offset);
 162                 wait_on_buffer(bh);
 163         }
 164
 165         if (!buffer_uptodate(bh)) {
 166                 printk (KERN_ERR "JBD: Failed to read block at offset %u\n",
 167                         offset);
 168                 brelse(bh);
 169                 return -EIO;
 170         }
 171
 172         *bhp = bh;
 173         return 0;
 174 }
 175
 176
 177 /*
 178  * Count the number of in-use tags in a journal descriptor block.
 179  */
 180
 181 static int count_tags(journal_t *journal, struct buffer_head *bh)
 182 {
 183         char *                  tagp;
 184         journal_block_tag_t *   tag;
 185         int                     nr = 0, size = journal->j_blocksize;
 186         int                     tag_bytes = journal_tag_bytes(journal);
 187
 188         tagp = &bh->b_data[sizeof(journal_header_t)];
 189
 190         while ((tagp - bh->b_data + tag_bytes) <= size) {
 191                 tag = (journal_block_tag_t *) tagp;
 192
 193                 nr++;
 194                 tagp += tag_bytes;
 195                 if (!(tag->t_flags & cpu_to_be32(JBD2_FLAG_SAME_UUID)))
 196                         tagp += 16;
 197
 198                 if (tag->t_flags & cpu_to_be32(JBD2_FLAG_LAST_TAG))
 199                         break;
 200         }
 201
 202         return nr;
 203 }
 204
 205
 206 /* Make sure we wrap around the log correctly! */
 207 #define wrap(journal, var)                                              \
 208 do {                                                                    \
 209         if (var >= (journal)->j_last)                                   \
 210                 var -= ((journal)->j_last - (journal)->j_first);        \
 211 } while (0)
 212
 213 /**
 214  * jbd2_journal_recover - recovers a on-disk journal
 215  * @journal: the journal to recover
 216  *
 217  * The primary function for recovering the log contents when mounting a
 218  * journaled device.
 219  *
 220  * Recovery is done in three passes.  In the first pass, we look for the
 221  * end of the log.  In the second, we assemble the list of revoke
 222  * blocks.  In the third and final pass, we replay any un-revoked blocks
 223  * in the log.
 224  */
 225 int jbd2_journal_recover(journal_t *journal)
 226 {
 227         int                     err;
 228         journal_superblock_t *  sb;
 229
 230         struct recovery_info    info;
 231
 232         memset(&info, 0, sizeof(info));
 233         sb = journal->j_superblock;
 234
 235         /*
 236          * The journal superblock's s_start field (the current log head)
 237          * is always zero if, and only if, the journal was cleanly
 238          * unmounted.
 239          */
 240
 241         if (!sb->s_start) {
 242                 jbd_debug(1, "No recovery required, last transaction %d\n",
 243                           be32_to_cpu(sb->s_sequence));
 244                 journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
 245                 return 0;
 246         }
 247
 248         err = do_one_pass(journal, &info, PASS_SCAN);
 249         if (!err)
 250                 err = do_one_pass(journal, &info, PASS_REVOKE);
 251         if (!err)
 252                 err = do_one_pass(journal, &info, PASS_REPLAY);
 253
 254         jbd_debug(1, "JBD: recovery, exit status %d, "
 255                   "recovered transactions %u to %u\n",
 256                   err, info.start_transaction, info.end_transaction);
 257         jbd_debug(1, "JBD: Replayed %d and revoked %d/%d blocks\n",
 258                   info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
 259
 260         /* Restart the log at the next transaction ID, thus invalidating
 261          * any existing commit records in the log. */
 262         journal->j_transaction_sequence = ++info.end_transaction;
 263
 264         jbd2_journal_clear_revoke(journal);
 265         sync_blockdev(journal->j_fs_dev);
 266         return err;
 267 }
 268
 269 /**
 270  * jbd2_journal_skip_recovery - Start journal and wipe exiting records
 271  * @journal: journal to startup
 272  *
 273  * Locate any valid recovery information from the journal and set up the
 274  * journal structures in memory to ignore it (presumably because the
 275  * caller has evidence that it is out of date).
 276  * This function does'nt appear to be exorted..
 277  *
 278  * We perform one pass over the journal to allow us to tell the user how
 279  * much recovery information is being erased, and to let us initialise
 280  * the journal transaction sequence numbers to the next unused ID.
 281  */
 282 int jbd2_journal_skip_recovery(journal_t *journal)
 283 {
 284         int                     err;
 285         journal_superblock_t *  sb;
 286
 287         struct recovery_info    info;
 288
 289         memset (&info, 0, sizeof(info));
 290         sb = journal->j_superblock;
 291
 292         err = do_one_pass(journal, &info, PASS_SCAN);
 293
 294         if (err) {
 295                 printk(KERN_ERR "JBD: error %d scanning journal\n", err);
 296                 ++journal->j_transaction_sequence;
 297         } else {
 298 #ifdef CONFIG_JBD2_DEBUG
 299                 int dropped = info.end_transaction - be32_to_cpu(sb->s_sequence);
 300 #endif
 301                 jbd_debug(1,
 302                           "JBD: ignoring %d transaction%s from the journal.\n",
 303                           dropped, (dropped == 1) ? "" : "s");
 304                 journal->j_transaction_sequence = ++info.end_transaction;
 305         }
 306
 307         journal->j_tail = 0;
 308         return err;
 309 }
 310
 311 static inline unsigned long long read_tag_block(int tag_bytes, journal_block_tag_t *tag)
 312 {
 313         unsigned long long block = be32_to_cpu(tag->t_blocknr);
 314         if (tag_bytes > JBD2_TAG_SIZE32)
 315                 block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
 316         return block;
 317 }
 318
 319 static int do_one_pass(journal_t *journal,
 320                         struct recovery_info *info, enum passtype pass)
 321 {
 322         unsigned int            first_commit_ID, next_commit_ID;
 323         unsigned long           next_log_block;
 324         int                     err, success = 0;
 325         journal_superblock_t *  sb;
 326         journal_header_t *      tmp;
 327         struct buffer_head *    bh;
 328         unsigned int            sequence;
 329         int                     blocktype;
 330         int                     tag_bytes = journal_tag_bytes(journal);
 331
 332         /* Precompute the maximum metadata descriptors in a descriptor block */
 333         int                     MAX_BLOCKS_PER_DESC;
 334         MAX_BLOCKS_PER_DESC = ((journal->j_blocksize-sizeof(journal_header_t))
 335                                / tag_bytes);
 336
 337         /*
 338          * First thing is to establish what we expect to find in the log
 339          * (in terms of transaction IDs), and where (in terms of log
 340          * block offsets): query the superblock.
 341          */
 342
 343         sb = journal->j_superblock;
 344         next_commit_ID = be32_to_cpu(sb->s_sequence);
 345         next_log_block = be32_to_cpu(sb->s_start);
 346
 347         first_commit_ID = next_commit_ID;
 348         if (pass == PASS_SCAN)
 349                 info->start_transaction = first_commit_ID;
 350
 351         jbd_debug(1, "Starting recovery pass %d\n", pass);
 352
 353         /*
 354          * Now we walk through the log, transaction by transaction,
 355          * making sure that each transaction has a commit block in the
 356          * expected place.  Each complete transaction gets replayed back
 357          * into the main filesystem.
 358          */
 359
 360         while (1) {
 361                 int                     flags;
 362                 char *                  tagp;
 363                 journal_block_tag_t *   tag;
 364                 struct buffer_head *    obh;
 365                 struct buffer_head *    nbh;
 366
 367                 cond_resched();         /* We're under lock_kernel() */
 368
 369                 /* If we already know where to stop the log traversal,
 370                  * check right now that we haven't gone past the end of
 371                  * the log. */
 372
 373                 if (pass != PASS_SCAN)
 374                         if (tid_geq(next_commit_ID, info->end_transaction))
 375                                 break;
 376
 377                 jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
 378                           next_commit_ID, next_log_block, journal->j_last);
 379
 380                 /* Skip over each chunk of the transaction looking
 381                  * either the next descriptor block or the final commit
 382                  * record. */
 383
 384                 jbd_debug(3, "JBD: checking block %ld\n", next_log_block);
 385                 err = jread(&bh, journal, next_log_block);
 386                 if (err)
 387                         goto failed;
 388
 389                 next_log_block++;
 390                 wrap(journal, next_log_block);
 391
 392                 /* What kind of buffer is it?
 393                  *
 394                  * If it is a descriptor block, check that it has the
 395                  * expected sequence number.  Otherwise, we're all done
 396                  * here. */
 397
 398                 tmp = (journal_header_t *)bh->b_data;
 399
 400                 if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
 401                         brelse(bh);
 402                         break;
 403                 }
 404
 405                 blocktype = be32_to_cpu(tmp->h_blocktype);
 406                 sequence = be32_to_cpu(tmp->h_sequence);
 407                 jbd_debug(3, "Found magic %d, sequence %d\n",
 408                           blocktype, sequence);
 409
 410                 if (sequence != next_commit_ID) {
 411                         brelse(bh);
 412                         break;
 413                 }
 414
 415                 /* OK, we have a valid descriptor block which matches
 416                  * all of the sequence number checks.  What are we going
 417                  * to do with it?  That depends on the pass... */
 418
 419                 switch(blocktype) {
 420                 case JBD2_DESCRIPTOR_BLOCK:
 421                         /* If it is a valid descriptor block, replay it
 422                          * in pass REPLAY; otherwise, just skip over the
 423                          * blocks it describes. */
 424                         if (pass != PASS_REPLAY) {
 425                                 next_log_block += count_tags(journal, bh);
 426                                 wrap(journal, next_log_block);
 427                                 brelse(bh);
 428                                 continue;
 429                         }
 430
 431                         /* A descriptor block: we can now write all of
 432                          * the data blocks.  Yay, useful work is finally
 433                          * getting done here! */
 434
 435                         tagp = &bh->b_data[sizeof(journal_header_t)];
 436                         while ((tagp - bh->b_data + tag_bytes)
 437                                <= journal->j_blocksize) {
 438                                 unsigned long io_block;
 439
 440                                 tag = (journal_block_tag_t *) tagp;
 441                                 flags = be32_to_cpu(tag->t_flags);
 442
 443                                 io_block = next_log_block++;
 444                                 wrap(journal, next_log_block);
 445                                 err = jread(&obh, journal, io_block);
 446                                 if (err) {
 447                                         /* Recover what we can, but
 448                                          * report failure at the end. */
 449                                         success = err;
 450                                         printk (KERN_ERR
 451                                                 "JBD: IO error %d recovering "
 452                                                 "block %ld in log\n",
 453                                                 err, io_block);
 454                                 } else {
 455                                         unsigned long long blocknr;
 456
 457                                         J_ASSERT(obh != NULL);
 458                                         blocknr = read_tag_block(tag_bytes,
 459                                                                  tag);
 460
 461                                         /* If the block has been
 462                                          * revoked, then we're all done
 463                                          * here. */
 464                                         if (jbd2_journal_test_revoke
 465                                             (journal, blocknr,
 466                                              next_commit_ID)) {
 467                                                 brelse(obh);
 468                                                 ++info->nr_revoke_hits;
 469                                                 goto skip_write;
 470                                         }
 471
 472                                         /* Find a buffer for the new
 473                                          * data being restored */
 474                                         nbh = __getblk(journal->j_fs_dev,
 475                                                         blocknr,
 476                                                         journal->j_blocksize);
 477                                         if (nbh == NULL) {
 478                                                 printk(KERN_ERR
 479                                                        "JBD: Out of memory "
 480                                                        "during recovery.\n");
 481                                                 err = -ENOMEM;
 482                                                 brelse(bh);
 483                                                 brelse(obh);
 484                                                 goto failed;
 485                                         }
 486
 487                                         lock_buffer(nbh);
 488                                         memcpy(nbh->b_data, obh->b_data,
 489                                                         journal->j_blocksize);
 490                                         if (flags & JBD2_FLAG_ESCAPE) {
 491                                                 *((__be32 *)bh->b_data) =
 492                                                 cpu_to_be32(JBD2_MAGIC_NUMBER);
 493                                         }
 494
 495                                         BUFFER_TRACE(nbh, "marking dirty");
 496                                         set_buffer_uptodate(nbh);
 497                                         mark_buffer_dirty(nbh);
 498                                         BUFFER_TRACE(nbh, "marking uptodate");
 499                                         ++info->nr_replays;
 500                                         /* ll_rw_block(WRITE, 1, &nbh); */
 501                                         unlock_buffer(nbh);
 502                                         brelse(obh);
 503                                         brelse(nbh);
 504                                 }
 505
 506                         skip_write:
 507                                 tagp += tag_bytes;
 508                                 if (!(flags & JBD2_FLAG_SAME_UUID))
 509                                         tagp += 16;
 510
 511                                 if (flags & JBD2_FLAG_LAST_TAG)
 512                                         break;
 513                         }
 514
 515                         brelse(bh);
 516                         continue;
 517
 518                 case JBD2_COMMIT_BLOCK:
 519                         /* Found an expected commit block: not much to
 520                          * do other than move on to the next sequence
 521                          * number. */
 522                         brelse(bh);
 523                         next_commit_ID++;
 524                         continue;
 525
 526                 case JBD2_REVOKE_BLOCK:
 527                         /* If we aren't in the REVOKE pass, then we can
 528                          * just skip over this block. */
 529                         if (pass != PASS_REVOKE) {
 530                                 brelse(bh);
 531                                 continue;
 532                         }
 533
 534                         err = scan_revoke_records(journal, bh,
 535                                                   next_commit_ID, info);
 536                         brelse(bh);
 537                         if (err)
 538                                 goto failed;
 539                         continue;
 540
 541                 default:
 542                         jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
 543                                   blocktype);
 544                         brelse(bh);
 545                         goto done;
 546                 }
 547         }
 548
 549  done:
 550         /*
 551          * We broke out of the log scan loop: either we came to the
 552          * known end of the log or we found an unexpected block in the
 553          * log.  If the latter happened, then we know that the "current"
 554          * transaction marks the end of the valid log.
 555          */
 556
 557         if (pass == PASS_SCAN)
 558                 info->end_transaction = next_commit_ID;
 559         else {
 560                 /* It's really bad news if different passes end up at
 561                  * different places (but possible due to IO errors). */
 562                 if (info->end_transaction != next_commit_ID) {
 563                         printk (KERN_ERR "JBD: recovery pass %d ended at "
 564                                 "transaction %u, expected %u\n",
 565                                 pass, next_commit_ID, info->end_transaction);
 566                         if (!success)
 567                                 success = -EIO;
 568                 }
 569         }
 570
 571         return success;
 572
 573  failed:
 574         return err;
 575 }
 576
 577
 578 /* Scan a revoke record, marking all blocks mentioned as revoked. */
 579
 580 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
 581                                tid_t sequence, struct recovery_info *info)
 582 {
 583         jbd2_journal_revoke_header_t *header;
 584         int offset, max;
 585         int record_len = 4;
 586
 587         header = (jbd2_journal_revoke_header_t *) bh->b_data;
 588         offset = sizeof(jbd2_journal_revoke_header_t);
 589         max = be32_to_cpu(header->r_count);
 590
 591         if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
 592                 record_len = 8;
 593
 594         while (offset + record_len <= max) {
 595                 unsigned long long blocknr;
 596                 int err;
 597
 598                 if (record_len == 4)
 599                         blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
 600                 else
 601                         blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
 602                 offset += record_len;
 603                 err = jbd2_journal_set_revoke(journal, blocknr, sequence);
 604                 if (err)
 605                         return err;
 606                 ++info->nr_revokes;
 607         }
 608         return 0;
 609 }