lustre/kernel_patches/patches/jbd-journal-chksum-2.6.18-vanilla.patch

   1 Index: linux-2.6.18.8/fs/jbd/commit.c
   2 ===================================================================
   3 --- linux-2.6.18.8.orig/fs/jbd/commit.c
   4 +++ linux-2.6.18.8/fs/jbd/commit.c
   5 @@ -22,6 +22,7 @@
   6  #include <linux/mm.h>
   7  #include <linux/pagemap.h>
   8  #include <linux/smp_lock.h>
   9 +#include <linux/crc32.h>
  10
  11
  12  /*
  13 @@ -95,19 +96,23 @@ static int inverted_lock(journal_t *jour
  14         return 1;
  15  }
  16
  17 -/* Done it all: now write the commit record.  We should have
  18 +/*
  19 + * Done it all: now submit the commit record.  We should have
  20   * cleaned up our previous buffers by now, so if we are in abort
  21   * mode we can now just skip the rest of the journal write
  22   * entirely.
  23   *
  24   * Returns 1 if the journal needs to be aborted or 0 on success
  25   */
  26 -static int journal_write_commit_record(journal_t *journal,
  27 -                                       transaction_t *commit_transaction)
  28 +static int journal_submit_commit_record(journal_t *journal,
  29 +                                       transaction_t *commit_transaction,
  30 +                                       struct buffer_head **cbh,
  31 +                                       __u32 crc32_sum)
  32  {
  33         struct journal_head *descriptor;
  34 +       struct commit_header *tmp;
  35         struct buffer_head *bh;
  36 -       int i, ret;
  37 +       int ret;
  38         int barrier_done = 0;
  39
  40         if (is_journal_aborted(journal))
  41 @@ -119,21 +124,34 @@ static int journal_write_commit_record(j
  42
  43         bh = jh2bh(descriptor);
  44
  45 -       /* AKPM: buglet - add `i' to tmp! */
  46 -       for (i = 0; i < bh->b_size; i += 512) {
  47 -               journal_header_t *tmp = (journal_header_t*)bh->b_data;
  48 -               tmp->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER);
  49 -               tmp->h_blocktype = cpu_to_be32(JFS_COMMIT_BLOCK);
  50 -               tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid);
  51 +       tmp = (struct commit_header *)bh->b_data;
  52 +       tmp->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER);
  53 +       tmp->h_blocktype = cpu_to_be32(JFS_COMMIT_BLOCK);
  54 +       tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid);
  55 +
  56 +       if (JFS_HAS_COMPAT_FEATURE(journal,
  57 +                               JFS_FEATURE_COMPAT_CHECKSUM)) {
  58 +               tmp->h_chksum_type      = JFS_CRC32_CHKSUM;
  59 +               tmp->h_chksum_size      = JFS_CRC32_CHKSUM_SIZE;
  60 +               tmp->h_chksum[0]        = cpu_to_be32(crc32_sum);
  61         }
  62
  63 -       JBUFFER_TRACE(descriptor, "write commit block");
  64 +       JBUFFER_TRACE(descriptor, "submit commit block");
  65 +       lock_buffer(bh);
  66 +
  67         set_buffer_dirty(bh);
  68 -       if (journal->j_flags & JFS_BARRIER) {
  69 +       set_buffer_uptodate(bh);
  70 +       bh->b_end_io = journal_end_buffer_io_sync;
  71 +
  72 +       if (journal->j_flags & JFS_BARRIER &&
  73 +               !JFS_HAS_COMPAT_FEATURE(journal,
  74 +                                        JFS_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
  75 +
  76                 set_buffer_ordered(bh);
  77                 barrier_done = 1;
  78         }
  79 -       ret = sync_dirty_buffer(bh);
  80 +       ret = submit_bh(WRITE, bh);
  81 +
  82         /* is it possible for another commit to fail at roughly
  83          * the same time as this one?  If so, we don't want to
  84          * trust the barrier flag in the super, but instead want
  85 @@ -154,12 +172,70 @@ static int journal_write_commit_record(j
  86                 clear_buffer_ordered(bh);
  87                 set_buffer_uptodate(bh);
  88                 set_buffer_dirty(bh);
  89 -               ret = sync_dirty_buffer(bh);
  90 +               ret = submit_bh(WRITE, bh);
  91         }
  92 -       put_bh(bh);             /* One for getblk() */
  93 -       journal_put_journal_head(descriptor);
  94 +       *cbh = bh;
  95 +       return ret;
  96 +}
  97 +
  98 +/*
  99 + * This function along with journal_submit_commit_record
 100 + * allows to write the commit record asynchronously.
 101 + */
 102 +static int journal_wait_on_commit_record(struct buffer_head *bh)
 103 +{
 104 +       int ret = 0;
 105 +
 106 +       clear_buffer_dirty(bh);
 107 +       wait_on_buffer(bh);
 108 +
 109 +       if (unlikely(!buffer_uptodate(bh)))
 110 +               ret = -EIO;
 111 +       put_bh(bh);            /* One for getblk() */
 112 +       journal_put_journal_head(bh2jh(bh));
 113 +
 114 +       return ret;
 115 +}
 116 +
 117 +/*
 118 + * Wait for all submitted IO to complete.
 119 + */
 120 +static int journal_wait_on_locked_list(journal_t *journal,
 121 +                                      transaction_t *commit_transaction)
 122 +{
 123 +       int ret = 0;
 124 +       struct journal_head *jh;
 125
 126 -       return (ret == -EIO);
 127 +       while (commit_transaction->t_locked_list) {
 128 +               struct buffer_head *bh;
 129 +
 130 +               jh = commit_transaction->t_locked_list->b_tprev;
 131 +               bh = jh2bh(jh);
 132 +               get_bh(bh);
 133 +               if (buffer_locked(bh)) {
 134 +                       spin_unlock(&journal->j_list_lock);
 135 +                       wait_on_buffer(bh);
 136 +                       if (unlikely(!buffer_uptodate(bh)))
 137 +                               ret = -EIO;
 138 +                       spin_lock(&journal->j_list_lock);
 139 +               }
 140 +               if (!inverted_lock(journal, bh)) {
 141 +                       put_bh(bh);
 142 +                       spin_lock(&journal->j_list_lock);
 143 +                       continue;
 144 +               }
 145 +               if (buffer_jbd(bh) && jh->b_jlist == BJ_Locked) {
 146 +                       __journal_unfile_buffer(jh);
 147 +                       jbd_unlock_bh_state(bh);
 148 +                       journal_remove_journal_head(bh);
 149 +                       put_bh(bh);
 150 +               } else {
 151 +                       jbd_unlock_bh_state(bh);
 152 +               }
 153 +               put_bh(bh);
 154 +               cond_resched_lock(&journal->j_list_lock);
 155 +       }
 156 +       return ret;
 157  }
 158
 159  void journal_do_submit_data(struct buffer_head **wbuf, int bufs)
 160 @@ -273,6 +349,20 @@ write_out_data:
 161         journal_do_submit_data(wbuf, bufs);
 162  }
 163
 164 +static inline __u32 jbd_checksum_data(__u32 crc32_sum, struct buffer_head *bh)
 165 +{
 166 +       struct page *page = bh->b_page;
 167 +       char *addr;
 168 +       __u32 checksum;
 169 +
 170 +       addr = kmap(page);
 171 +       checksum = crc32_be(crc32_sum,
 172 +                           (void *)(addr + offset_in_page(bh->b_data)),
 173 +                           bh->b_size);
 174 +       kunmap(page);
 175 +       return checksum;
 176 +}
 177 +
 178  /*
 179   * journal_commit_transaction
 180   *
 181 @@ -296,6 +386,8 @@ void journal_commit_transaction(journal_
 182         int first_tag = 0;
 183         int tag_flag;
 184         int i;
 185 +       struct buffer_head *cbh = NULL; /* For transactional checksums */
 186 +       __u32 crc32_sum = ~0;
 187
 188         /*
 189          * First job: lock down the current transaction and wait for
 190 @@ -439,38 +531,14 @@ void journal_commit_transaction(journal_
 191         journal_submit_data_buffers(journal, commit_transaction);
 192
 193         /*
 194 -        * Wait for all previously submitted IO to complete.
 195 +        * Wait for all previously submitted IO to complete if commit
 196 +        * record is to be written synchronously.
 197          */
 198         spin_lock(&journal->j_list_lock);
 199 -       while (commit_transaction->t_locked_list) {
 200 -               struct buffer_head *bh;
 201 -
 202 -               jh = commit_transaction->t_locked_list->b_tprev;
 203 -               bh = jh2bh(jh);
 204 -               get_bh(bh);
 205 -               if (buffer_locked(bh)) {
 206 -                       spin_unlock(&journal->j_list_lock);
 207 -                       wait_on_buffer(bh);
 208 -                       if (unlikely(!buffer_uptodate(bh)))
 209 -                               err = -EIO;
 210 -                       spin_lock(&journal->j_list_lock);
 211 -               }
 212 -               if (!inverted_lock(journal, bh)) {
 213 -                       put_bh(bh);
 214 -                       spin_lock(&journal->j_list_lock);
 215 -                       continue;
 216 -               }
 217 -               if (buffer_jbd(bh) && jh->b_jlist == BJ_Locked) {
 218 -                       __journal_unfile_buffer(jh);
 219 -                       jbd_unlock_bh_state(bh);
 220 -                       journal_remove_journal_head(bh);
 221 -                       put_bh(bh);
 222 -               } else {
 223 -                       jbd_unlock_bh_state(bh);
 224 -               }
 225 -               put_bh(bh);
 226 -               cond_resched_lock(&journal->j_list_lock);
 227 -       }
 228 +       if (!JFS_HAS_INCOMPAT_FEATURE(journal,
 229 +               JFS_FEATURE_INCOMPAT_ASYNC_COMMIT))
 230 +               err = journal_wait_on_locked_list(journal,
 231 +                                                 commit_transaction);
 232         spin_unlock(&journal->j_list_lock);
 233
 234         if (err)
 235 @@ -643,6 +711,16 @@ void journal_commit_transaction(journal_
 236  start_journal_io:
 237                         for (i = 0; i < bufs; i++) {
 238                                 struct buffer_head *bh = wbuf[i];
 239 +                               /*
 240 +                                * Compute checksum.
 241 +                                */
 242 +                               if (JFS_HAS_COMPAT_FEATURE(journal,
 243 +                                       JFS_FEATURE_COMPAT_CHECKSUM)) {
 244 +                                       crc32_sum =
 245 +                                               jbd_checksum_data(crc32_sum,
 246 +                                                                  bh);
 247 +                               }
 248 +
 249                                 lock_buffer(bh);
 250                                 clear_buffer_dirty(bh);
 251                                 set_buffer_uptodate(bh);
 252 @@ -659,6 +737,23 @@ start_journal_io:
 253                 }
 254         }
 255
 256 +       /* Done it all: now write the commit record asynchronously. */
 257 +
 258 +       if (JFS_HAS_INCOMPAT_FEATURE(journal,
 259 +               JFS_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
 260 +               err = journal_submit_commit_record(journal, commit_transaction,
 261 +                                                &cbh, crc32_sum);
 262 +               if (err)
 263 +                       __journal_abort_hard(journal);
 264 +
 265 +               spin_lock(&journal->j_list_lock);
 266 +               err = journal_wait_on_locked_list(journal,
 267 +                                               commit_transaction);
 268 +               spin_unlock(&journal->j_list_lock);
 269 +               if (err)
 270 +                       __journal_abort_hard(journal);
 271 +       }
 272 +
 273         /* Lo and behold: we have just managed to send a transaction to
 274             the log.  Before we can commit it, wait for the IO so far to
 275             complete.  Control buffers being written are on the
 276 @@ -757,9 +852,15 @@ wait_for_iobuf:
 277         }
 278
 279         jbd_debug(3, "JBD: commit phase 6\n");
 280 -
 281 -       if (journal_write_commit_record(journal, commit_transaction))
 282 -               err = -EIO;
 283 +
 284 +       if (!JFS_HAS_INCOMPAT_FEATURE(journal,
 285 +               JFS_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
 286 +               err = journal_submit_commit_record(journal, commit_transaction,
 287 +                                               &cbh, crc32_sum);
 288 +               if (err)
 289 +                       __journal_abort_hard(journal);
 290 +       }
 291 +       err = journal_wait_on_commit_record(cbh);
 292
 293         if (err)
 294                 __journal_abort_hard(journal);
 295 Index: linux-2.6.18.8/include/linux/jbd.h
 296 ===================================================================
 297 --- linux-2.6.18.8.orig/include/linux/jbd.h
 298 +++ linux-2.6.18.8/include/linux/jbd.h
 299 @@ -148,6 +148,29 @@ typedef struct journal_header_s
 300         __be32          h_sequence;
 301  } journal_header_t;
 302
 303 +/*
 304 + * Checksum types.
 305 + */
 306 +#define JFS_CRC32_CHKSUM   1
 307 +#define JFS_MD5_CHKSUM     2
 308 +#define JFS_SHA1_CHKSUM    3
 309 +
 310 +#define JFS_CRC32_CHKSUM_SIZE 4
 311 +
 312 +#define JFS_CHECKSUM_BYTES (32 / sizeof(u32))
 313 +/*
 314 + * Commit block header for storing transactional checksums:
 315 + */
 316 +struct commit_header
 317 +{
 318 +       __be32          h_magic;
 319 +       __be32          h_blocktype;
 320 +       __be32          h_sequence;
 321 +       unsigned char   h_chksum_type;
 322 +       unsigned char   h_chksum_size;
 323 +       unsigned char   h_padding[2];
 324 +       __be32          h_chksum[JFS_CHECKSUM_BYTES];
 325 +};
 326
 327  /*
 328   * The block tag: used to describe a single buffer in the journal
 329 @@ -234,12 +257,16 @@ typedef struct journal_superblock_s
 330         ((j)->j_format_version >= 2 &&                                  \
 331          ((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask))))
 332
 333 -#define JFS_FEATURE_INCOMPAT_REVOKE    0x00000001
 334 +#define JFS_FEATURE_COMPAT_CHECKSUM    0x00000001
 335 +
 336 +#define JFS_FEATURE_INCOMPAT_REVOKE            0x00000001
 337 +#define JFS_FEATURE_INCOMPAT_ASYNC_COMMIT      0x00000004
 338
 339  /* Features known to this kernel version: */
 340 -#define JFS_KNOWN_COMPAT_FEATURES      0
 341 +#define JFS_KNOWN_COMPAT_FEATURES      JFS_FEATURE_COMPAT_CHECKSUM
 342  #define JFS_KNOWN_ROCOMPAT_FEATURES    0
 343 -#define JFS_KNOWN_INCOMPAT_FEATURES    JFS_FEATURE_INCOMPAT_REVOKE
 344 +#define JFS_KNOWN_INCOMPAT_FEATURES    JFS_FEATURE_INCOMPAT_REVOKE | \
 345 +                                       JFS_FEATURE_INCOMPAT_ASYNC_COMMIT
 346
 347  #ifdef __KERNEL__
 348
 349 @@ -1053,6 +1080,8 @@ extern int           journal_check_available_fe
 350                    (journal_t *, unsigned long, unsigned long, unsigned long);
 351  extern int        journal_set_features
 352                    (journal_t *, unsigned long, unsigned long, unsigned long);
 353 +extern int        journal_clear_features
 354 +                  (journal_t *, unsigned long, unsigned long, unsigned long);
 355  extern int        journal_create     (journal_t *);
 356  extern int        journal_load       (journal_t *journal);
 357  extern void       journal_destroy    (journal_t *);
 358 Index: linux-2.6.18.8/fs/jbd/recovery.c
 359 ===================================================================
 360 --- linux-2.6.18.8.orig/fs/jbd/recovery.c
 361 +++ linux-2.6.18.8/fs/jbd/recovery.c
 362 @@ -21,6 +21,7 @@
 363  #include <linux/jbd.h>
 364  #include <linux/errno.h>
 365  #include <linux/slab.h>
 366 +#include <linux/crc32.h>
 367  #endif
 368
 369  /*
 370 @@ -307,6 +308,37 @@ int journal_skip_recovery(journal_t *jou
 371         return err;
 372  }
 373
 374 +/*
 375 + * calc_chksums calculates the checksums for the blocks described in the
 376 + * descriptor block.
 377 + */
 378 +static int calc_chksums(journal_t *journal, struct buffer_head *bh,
 379 +                      unsigned long *next_log_block, __u32 *crc32_sum)
 380 +{
 381 +       int i, num_blks, err;
 382 +       unsigned io_block;
 383 +       struct buffer_head *obh;
 384 +
 385 +       num_blks = count_tags(bh, journal->j_blocksize);
 386 +       /* Calculate checksum of the descriptor block. */
 387 +       *crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
 388 +
 389 +       for (i = 0; i < num_blks; i++) {
 390 +               io_block = (*next_log_block)++;
 391 +               wrap(journal, *next_log_block);
 392 +               err = jread(&obh, journal, io_block);
 393 +               if (err) {
 394 +                       printk(KERN_ERR "JBD: IO error %d recovering block "
 395 +                               "%u in log\n", err, io_block);
 396 +                       return 1;
 397 +               } else {
 398 +                       *crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
 399 +                                    obh->b_size);
 400 +               }
 401 +       }
 402 +       return 0;
 403 +}
 404 +
 405  static int do_one_pass(journal_t *journal,
 406                         struct recovery_info *info, enum passtype pass)
 407  {
 408 @@ -318,6 +350,7 @@ static int do_one_pass(journal_t *journa
 409         struct buffer_head *    bh;
 410         unsigned int            sequence;
 411         int                     blocktype;
 412 +       __u32                   crc32_sum = ~0; /* Transactional Checksums */
 413
 414         /* Precompute the maximum metadata descriptors in a descriptor block */
 415         int                     MAX_BLOCKS_PER_DESC;
 416 @@ -409,9 +442,24 @@ static int do_one_pass(journal_t *journa
 417                 switch(blocktype) {
 418                 case JFS_DESCRIPTOR_BLOCK:
 419                         /* If it is a valid descriptor block, replay it
 420 -                        * in pass REPLAY; otherwise, just skip over the
 421 -                        * blocks it describes. */
 422 +                        * in pass REPLAY; if journal_checksums enabled, then
 423 +                        * calculate checksums in PASS_SCAN, otherwise,
 424 +                        * just skip over the blocks it describes. */
 425                         if (pass != PASS_REPLAY) {
 426 +                               if (pass == PASS_SCAN &&
 427 +                                   JFS_HAS_COMPAT_FEATURE(journal,
 428 +                                           JFS_FEATURE_COMPAT_CHECKSUM) &&
 429 +                                   !info->end_transaction) {
 430 +                                       if (calc_chksums(journal, bh,
 431 +                                                       &next_log_block,
 432 +                                                       &crc32_sum)) {
 433 +                                               brelse(bh);
 434 +                                               break;
 435 +                                       }
 436 +                                       brelse(bh);
 437 +                                       continue;
 438 +                               }
 439 +
 440                                 next_log_block +=
 441                                         count_tags(bh, journal->j_blocksize);
 442                                 wrap(journal, next_log_block);
 443 @@ -506,9 +554,97 @@ static int do_one_pass(journal_t *journa
 444                         continue;
 445
 446                 case JFS_COMMIT_BLOCK:
 447 -                       /* Found an expected commit block: not much to
 448 -                        * do other than move on to the next sequence
 449 +                       /*     How to differentiate between interrupted commit
 450 +                        *               and journal corruption ?
 451 +                        *
 452 +                        * {nth transaction}
 453 +                        *        Checksum Verification Failed
 454 +                        *                       |
 455 +                        *               ____________________
 456 +                        *              |                    |
 457 +                        *      async_commit             sync_commit
 458 +                        *              |                    |
 459 +                        *              | GO TO NEXT    "Journal Corruption"
 460 +                        *              | TRANSACTION
 461 +                        *              |
 462 +                        * {(n+1)th transanction}
 463 +                        *              |
 464 +                        *       _______|______________
 465 +                        *      |                     |
 466 +                        * Commit block found   Commit block not found
 467 +                        *      |                     |
 468 +                        * "Journal Corruption"       |
 469 +                        *               _____________|__________
 470 +                        *              |                       |
 471 +                        *      nth trans corrupt       OR   nth trans
 472 +                        *      and (n+1)th interrupted     interrupted
 473 +                        *      before commit block
 474 +                        *      could reach the disk.
 475 +                        *      (Cannot find the difference in above
 476 +                        *       mentioned conditions. Hence assume
 477 +                        *       "Interrupted Commit".)
 478 +                        */
 479 +
 480 +                       /* Found an expected commit block: if checksums
 481 +                        * are present verify them in PASS_SCAN; else not
 482 +                        * much to do other than move on to the next sequence
 483                          * number. */
 484 +                       if (pass == PASS_SCAN &&
 485 +                           JFS_HAS_COMPAT_FEATURE(journal,
 486 +                                   JFS_FEATURE_COMPAT_CHECKSUM)) {
 487 +                               int chksum_err, chksum_seen;
 488 +                               struct commit_header *cbh =
 489 +                                       (struct commit_header *)bh->b_data;
 490 +                               unsigned found_chksum =
 491 +                                               be32_to_cpu(cbh->h_chksum[0]);
 492 +
 493 +                               chksum_err = chksum_seen = 0;
 494 +
 495 +                               if (info->end_transaction) {
 496 +                                       printk(KERN_ERR "JBD: Transaction %u "
 497 +                                               "found to be corrupt.\n",
 498 +                                               next_commit_ID - 1);
 499 +                                       brelse(bh);
 500 +                                       break;
 501 +                               }
 502 +
 503 +                               if (crc32_sum == found_chksum &&
 504 +                                   cbh->h_chksum_type == JFS_CRC32_CHKSUM &&
 505 +                                   cbh->h_chksum_size ==
 506 +                                               JFS_CRC32_CHKSUM_SIZE) {
 507 +                                      chksum_seen = 1;
 508 +                               } else if (!(cbh->h_chksum_type == 0 &&
 509 +                                            cbh->h_chksum_size == 0 &&
 510 +                                            found_chksum == 0 &&
 511 +                                            !chksum_seen)) {
 512 +                               /*
 513 +                                * If fs is mounted using an old kernel and then
 514 +                                * kernel with journal_chksum is used then we
 515 +                                * get a situation where the journal flag has
 516 +                                * checksum flag set but checksums are not
 517 +                                * present i.e chksum = 0, in the individual
 518 +                                * commit blocks.
 519 +                                * Hence to avoid checksum failures, in this
 520 +                                * situation, this extra check is added.
 521 +                                */
 522 +                                               chksum_err = 1;
 523 +                               }
 524 +
 525 +                               if (chksum_err) {
 526 +                                       info->end_transaction = next_commit_ID;
 527 +
 528 +                                       if (!JFS_HAS_COMPAT_FEATURE(journal,
 529 +                                           JFS_FEATURE_INCOMPAT_ASYNC_COMMIT)){
 530 +                                               printk(KERN_ERR
 531 +                                                      "JBD: Transaction %u "
 532 +                                                      "found to be corrupt.\n",
 533 +                                                      next_commit_ID);
 534 +                                               brelse(bh);
 535 +                                               break;
 536 +                                       }
 537 +                               }
 538 +                               crc32_sum = ~0;
 539 +                       }
 540                         brelse(bh);
 541                         next_commit_ID++;
 542                         continue;
 543 @@ -544,9 +680,10 @@ static int do_one_pass(journal_t *journa
 544          * transaction marks the end of the valid log.
 545          */
 546
 547 -       if (pass == PASS_SCAN)
 548 -               info->end_transaction = next_commit_ID;
 549 -       else {
 550 +       if (pass == PASS_SCAN) {
 551 +               if (!info->end_transaction)
 552 +                       info->end_transaction = next_commit_ID;
 553 +       } else {
 554                 /* It's really bad news if different passes end up at
 555                  * different places (but possible due to IO errors). */
 556                 if (info->end_transaction != next_commit_ID) {
 557 Index: linux-2.6.18.8/fs/jbd/journal.c
 558 ===================================================================
 559 --- linux-2.6.18.8.orig/fs/jbd/journal.c
 560 +++ linux-2.6.18.8/fs/jbd/journal.c
 561 @@ -67,6 +67,7 @@ EXPORT_SYMBOL(journal_update_format);
 562  EXPORT_SYMBOL(journal_check_used_features);
 563  EXPORT_SYMBOL(journal_check_available_features);
 564  EXPORT_SYMBOL(journal_set_features);
 565 +EXPORT_SYMBOL(journal_clear_features);
 566  EXPORT_SYMBOL(journal_create);
 567  EXPORT_SYMBOL(journal_load);
 568  EXPORT_SYMBOL(journal_destroy);
 569 @@ -1573,6 +1574,33 @@ int journal_set_features (journal_t *jou
 570         return 1;
 571  }
 572
 573 +/**
 574 + * int journal_clear_features () - Clear a given journal feature in the superblock
 575 + * @journal: Journal to act on.
 576 + * @compat: bitmask of compatible features
 577 + * @ro: bitmask of features that force read-only mount
 578 + * @incompat: bitmask of incompatible features
 579 + *
 580 + * Clear a given journal feature as present on the
 581 + * superblock.  Returns true if the requested features could be reset.
 582 + *
 583 + */
 584 +int journal_clear_features (journal_t *journal, unsigned long compat,
 585 +                         unsigned long ro, unsigned long incompat)
 586 +{
 587 +       journal_superblock_t *sb;
 588 +
 589 +       jbd_debug(1, "Clear features 0x%lx/0x%lx/0x%lx\n",
 590 +                 compat, ro, incompat);
 591 +
 592 +       sb = journal->j_superblock;
 593 +
 594 +       sb->s_feature_compat    &= ~cpu_to_be32(compat);
 595 +       sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
 596 +       sb->s_feature_incompat  &= ~cpu_to_be32(incompat);
 597 +
 598 +       return 1;
 599 +}
 600
 601  /**
 602   * int journal_update_format () - Update on-disk journal structure.
 603 Index: linux-2.6.18.8/fs/Kconfig
 604 ===================================================================
 605 --- linux-2.6.18.8.orig/fs/Kconfig
 606 +++ linux-2.6.18.8/fs/Kconfig
 607 @@ -140,6 +140,7 @@ config EXT3_FS_SECURITY
 608
 609  config JBD
 610         tristate
 611 +       select CRC32
 612         help
 613           This is a generic journaling layer for block devices.  It is
 614           currently used by the ext3 and OCFS2 file systems, but it could
 615 Index: linux-2.6.18.8/Documentation/filesystems/ext3.txt
 616 ===================================================================
 617 --- linux-2.6.18.8.orig/Documentation/filesystems/ext3.txt
 618 +++ linux-2.6.18.8/Documentation/filesystems/ext3.txt
 619 @@ -14,6 +14,16 @@ Options
 620  When mounting an ext3 filesystem, the following option are accepted:
 621  (*) == default
 622
 623 +journal_checksum       Enable checksumming of the journal transactions.
 624 +                       This will allow the recovery code in e2fsck and the
 625 +                       kernel to detect corruption in the kernel.  It is a
 626 +                       compatible change and will be ignored by older kernels.
 627 +
 628 +journal_async_commit   Commit block can be written to disk without waiting
 629 +                       for descriptor blocks. If enabled older kernels cannot
 630 +                       mount the device. This will enable 'journal_checksum'
 631 +                       internally.
 632 +
 633  journal=update         Update the ext3 file system's journal to the current
 634                         format.
 635