lustre/kernel_patches/patches/jbd-journal-chksum-2.6-sles10.patch

   1 Index: linux-2.6.16.53-0.16/fs/jbd/commit.c
   2 ===================================================================
   3 --- linux-2.6.16.53-0.16.orig/fs/jbd/commit.c
   4 +++ linux-2.6.16.53-0.16/fs/jbd/commit.c
   5 @@ -22,6 +22,7 @@
   6  #include <linux/pagemap.h>
   7  #include <linux/smp_lock.h>
   8  #include <linux/jiffies.h>
   9 +#include <linux/crc32.h>
  10
  11  /*
  12   * Default IO end handler for temporary BJ_IO buffer_heads.
  13 @@ -94,19 +95,23 @@ 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 @@ -118,21 +123,34 @@ 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 @@ -153,12 +171,84 @@ 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 -       return (ret == -EIO);
  99 +/*
 100 + * This function along with journal_submit_commit_record
 101 + * allows to write the commit record asynchronously.
 102 + */
 103 +static int journal_wait_on_commit_record(struct buffer_head *bh)
 104 +{
 105 +       int ret = 0;
 106 +
 107 +       clear_buffer_dirty(bh);
 108 +       wait_on_buffer(bh);
 109 +
 110 +       if (unlikely(!buffer_uptodate(bh)))
 111 +               ret = -EIO;
 112 +       put_bh(bh);            /* One for getblk() */
 113 +       journal_put_journal_head(bh2jh(bh));
 114 +
 115 +       return ret;
 116 +}
 117 +
 118 +/*
 119 + * Wait for all submitted IO to complete.
 120 + */
 121 +static int journal_wait_on_locked_list(journal_t *journal,
 122 +                                      transaction_t *commit_transaction)
 123 +{
 124 +       int ret = 0;
 125 +       struct journal_head *jh;
 126 +
 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 +static inline __u32 jbd_checksum_data(__u32 crc32_sum, struct buffer_head *bh)
 160 +{
 161 +       struct page *page = bh->b_page;
 162 +       char *addr;
 163 +       __u32 checksum;
 164 +
 165 +       addr = kmap(page);
 166 +       checksum = crc32_be(crc32_sum,
 167 +                           (void *)(addr + offset_in_page(bh->b_data)),
 168 +                           bh->b_size);
 169 +       kunmap(page);
 170 +       return checksum;
 171  }
 172
 173  /*
 174 @@ -184,6 +274,8 @@ void journal_commit_transaction(journal_
 175         int first_tag = 0;
 176         int tag_flag;
 177         int i;
 178 +       struct buffer_head *cbh = NULL; /* For transactional checksums */
 179 +       __u32 crc32_sum = ~0;
 180
 181         /*
 182          * First job: lock down the current transaction and wait for
 183 @@ -395,37 +487,14 @@ write_out_data:
 184         }
 185
 186         /*
 187 -        * Wait for all previously submitted IO to complete.
 188 +        * Wait for all previously submitted IO to complete if commit
 189 +        * record is to be written synchronously.
 190          */
 191 -       while (commit_transaction->t_locked_list) {
 192 -               struct buffer_head *bh;
 193 +       if (!JFS_HAS_INCOMPAT_FEATURE(journal,
 194 +               JFS_FEATURE_INCOMPAT_ASYNC_COMMIT))
 195 +               err = journal_wait_on_locked_list(journal,
 196 +                                                 commit_transaction);
 197
 198 -               jh = commit_transaction->t_locked_list->b_tprev;
 199 -               bh = jh2bh(jh);
 200 -               get_bh(bh);
 201 -               if (buffer_locked(bh)) {
 202 -                       spin_unlock(&journal->j_list_lock);
 203 -                       wait_on_buffer(bh);
 204 -                       if (unlikely(!buffer_uptodate(bh)))
 205 -                               err = -EIO;
 206 -                       spin_lock(&journal->j_list_lock);
 207 -               }
 208 -               if (!inverted_lock(journal, bh)) {
 209 -                       put_bh(bh);
 210 -                       spin_lock(&journal->j_list_lock);
 211 -                       continue;
 212 -               }
 213 -               if (buffer_jbd(bh) && jh->b_jlist == BJ_Locked) {
 214 -                       __journal_unfile_buffer(jh);
 215 -                       jbd_unlock_bh_state(bh);
 216 -                       journal_remove_journal_head(bh);
 217 -                       put_bh(bh);
 218 -               } else {
 219 -                       jbd_unlock_bh_state(bh);
 220 -               }
 221 -               put_bh(bh);
 222 -               cond_resched_lock(&journal->j_list_lock);
 223 -       }
 224         spin_unlock(&journal->j_list_lock);
 225
 226         if (err)
 227 @@ -598,6 +667,16 @@ write_out_data:
 228  start_journal_io:
 229                         for (i = 0; i < bufs; i++) {
 230                                 struct buffer_head *bh = wbuf[i];
 231 +                               /*
 232 +                                * Compute checksum.
 233 +                                */
 234 +                               if (JFS_HAS_COMPAT_FEATURE(journal,
 235 +                                       JFS_FEATURE_COMPAT_CHECKSUM)) {
 236 +                                       crc32_sum =
 237 +                                               jbd_checksum_data(crc32_sum,
 238 +                                                                  bh);
 239 +                               }
 240 +
 241                                 lock_buffer(bh);
 242                                 clear_buffer_dirty(bh);
 243                                 set_buffer_uptodate(bh);
 244 @@ -614,6 +693,23 @@ start_journal_io:
 245                 }
 246         }
 247
 248 +       /* Done it all: now write the commit record asynchronously. */
 249 +
 250 +       if (JFS_HAS_INCOMPAT_FEATURE(journal,
 251 +               JFS_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
 252 +               err = journal_submit_commit_record(journal, commit_transaction,
 253 +                                                &cbh, crc32_sum);
 254 +               if (err)
 255 +                       __journal_abort_hard(journal);
 256 +
 257 +               spin_lock(&journal->j_list_lock);
 258 +               err = journal_wait_on_locked_list(journal,
 259 +                                               commit_transaction);
 260 +               spin_unlock(&journal->j_list_lock);
 261 +               if (err)
 262 +                       __journal_abort_hard(journal);
 263 +       }
 264 +
 265         /* Lo and behold: we have just managed to send a transaction to
 266             the log.  Before we can commit it, wait for the IO so far to
 267             complete.  Control buffers being written are on the
 268 @@ -712,9 +808,15 @@ wait_for_iobuf:
 269         }
 270
 271         jbd_debug(3, "JBD: commit phase 6\n");
 272 -
 273 -       if (journal_write_commit_record(journal, commit_transaction))
 274 -               err = -EIO;
 275 +
 276 +       if (!JFS_HAS_INCOMPAT_FEATURE(journal,
 277 +               JFS_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
 278 +               err = journal_submit_commit_record(journal, commit_transaction,
 279 +                                               &cbh, crc32_sum);
 280 +               if (err)
 281 +                       __journal_abort_hard(journal);
 282 +       }
 283 +       err = journal_wait_on_commit_record(cbh);
 284
 285         if (err)
 286                 __journal_abort_hard(journal);
 287 Index: linux-2.6.16.53-0.16/include/linux/jbd.h
 288 ===================================================================
 289 --- linux-2.6.16.53-0.16.orig/include/linux/jbd.h
 290 +++ linux-2.6.16.53-0.16/include/linux/jbd.h
 291 @@ -142,6 +142,29 @@ typedef struct journal_header_s
 292         __be32          h_sequence;
 293  } journal_header_t;
 294
 295 +/*
 296 + * Checksum types.
 297 + */
 298 +#define JFS_CRC32_CHKSUM   1
 299 +#define JFS_MD5_CHKSUM     2
 300 +#define JFS_SHA1_CHKSUM    3
 301 +
 302 +#define JFS_CRC32_CHKSUM_SIZE 4
 303 +
 304 +#define JFS_CHECKSUM_BYTES (32 / sizeof(u32))
 305 +/*
 306 + * Commit block header for storing transactional checksums:
 307 + */
 308 +struct commit_header
 309 +{
 310 +       __be32          h_magic;
 311 +       __be32          h_blocktype;
 312 +       __be32          h_sequence;
 313 +       unsigned char   h_chksum_type;
 314 +       unsigned char   h_chksum_size;
 315 +       unsigned char   h_padding[2];
 316 +       __be32          h_chksum[JFS_CHECKSUM_BYTES];
 317 +};
 318
 319  /*
 320   * The block tag: used to describe a single buffer in the journal
 321 @@ -228,12 +251,16 @@ typedef struct journal_superblock_s
 322         ((j)->j_format_version >= 2 &&                                  \
 323          ((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask))))
 324
 325 -#define JFS_FEATURE_INCOMPAT_REVOKE    0x00000001
 326 +#define JFS_FEATURE_COMPAT_CHECKSUM    0x00000001
 327 +
 328 +#define JFS_FEATURE_INCOMPAT_REVOKE            0x00000001
 329 +#define JFS_FEATURE_INCOMPAT_ASYNC_COMMIT      0x00000004
 330
 331  /* Features known to this kernel version: */
 332 -#define JFS_KNOWN_COMPAT_FEATURES      0
 333 +#define JFS_KNOWN_COMPAT_FEATURES      JFS_FEATURE_COMPAT_CHECKSUM
 334  #define JFS_KNOWN_ROCOMPAT_FEATURES    0
 335 -#define JFS_KNOWN_INCOMPAT_FEATURES    JFS_FEATURE_INCOMPAT_REVOKE
 336 +#define JFS_KNOWN_INCOMPAT_FEATURES    JFS_FEATURE_INCOMPAT_REVOKE | \
 337 +                                       JFS_FEATURE_INCOMPAT_ASYNC_COMMIT
 338
 339  #ifdef __KERNEL__
 340
 341 @@ -1041,6 +1068,8 @@ extern int           journal_check_available_fe
 342                    (journal_t *, unsigned long, unsigned long, unsigned long);
 343  extern int        journal_set_features
 344                    (journal_t *, unsigned long, unsigned long, unsigned long);
 345 +extern int        journal_clear_features
 346 +                  (journal_t *, unsigned long, unsigned long, unsigned long);
 347  extern int        journal_create     (journal_t *);
 348  extern int        journal_load       (journal_t *journal);
 349  extern void       journal_destroy    (journal_t *);
 350 Index: linux-2.6.16.53-0.16/fs/jbd/recovery.c
 351 ===================================================================
 352 --- linux-2.6.16.53-0.16.orig/fs/jbd/recovery.c
 353 +++ linux-2.6.16.53-0.16/fs/jbd/recovery.c
 354 @@ -21,6 +21,7 @@
 355  #include <linux/jbd.h>
 356  #include <linux/errno.h>
 357  #include <linux/slab.h>
 358 +#include <linux/crc32.h>
 359  #endif
 360
 361  /*
 362 @@ -307,6 +308,37 @@ int journal_skip_recovery(journal_t *jou
 363         return err;
 364  }
 365
 366 +/*
 367 + * calc_chksums calculates the checksums for the blocks described in the
 368 + * descriptor block.
 369 + */
 370 +static int calc_chksums(journal_t *journal, struct buffer_head *bh,
 371 +                      unsigned long *next_log_block, __u32 *crc32_sum)
 372 +{
 373 +       int i, num_blks, err;
 374 +       unsigned io_block;
 375 +       struct buffer_head *obh;
 376 +
 377 +       num_blks = count_tags(bh, journal->j_blocksize);
 378 +       /* Calculate checksum of the descriptor block. */
 379 +       *crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
 380 +
 381 +       for (i = 0; i < num_blks; i++) {
 382 +               io_block = (*next_log_block)++;
 383 +               wrap(journal, *next_log_block);
 384 +               err = jread(&obh, journal, io_block);
 385 +               if (err) {
 386 +                       printk(KERN_ERR "JBD: IO error %d recovering block "
 387 +                               "%u in log\n", err, io_block);
 388 +                       return 1;
 389 +               } else {
 390 +                       *crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
 391 +                                    obh->b_size);
 392 +               }
 393 +       }
 394 +       return 0;
 395 +}
 396 +
 397  static int do_one_pass(journal_t *journal,
 398                         struct recovery_info *info, enum passtype pass)
 399  {
 400 @@ -318,6 +350,7 @@ static int do_one_pass(journal_t *journa
 401         struct buffer_head *    bh;
 402         unsigned int            sequence;
 403         int                     blocktype;
 404 +       __u32                   crc32_sum = ~0; /* Transactional Checksums */
 405
 406         /* Precompute the maximum metadata descriptors in a descriptor block */
 407         int                     MAX_BLOCKS_PER_DESC;
 408 @@ -409,9 +442,24 @@ static int do_one_pass(journal_t *journa
 409                 switch(blocktype) {
 410                 case JFS_DESCRIPTOR_BLOCK:
 411                         /* If it is a valid descriptor block, replay it
 412 -                        * in pass REPLAY; otherwise, just skip over the
 413 -                        * blocks it describes. */
 414 +                        * in pass REPLAY; if journal_checksums enabled, then
 415 +                        * calculate checksums in PASS_SCAN, otherwise,
 416 +                        * just skip over the blocks it describes. */
 417                         if (pass != PASS_REPLAY) {
 418 +                               if (pass == PASS_SCAN &&
 419 +                                   JFS_HAS_COMPAT_FEATURE(journal,
 420 +                                           JFS_FEATURE_COMPAT_CHECKSUM) &&
 421 +                                   !info->end_transaction) {
 422 +                                       if (calc_chksums(journal, bh,
 423 +                                                       &next_log_block,
 424 +                                                       &crc32_sum)) {
 425 +                                               brelse(bh);
 426 +                                               break;
 427 +                                       }
 428 +                                       brelse(bh);
 429 +                                       continue;
 430 +                               }
 431 +
 432                                 next_log_block +=
 433                                         count_tags(bh, journal->j_blocksize);
 434                                 wrap(journal, next_log_block);
 435 @@ -506,9 +554,97 @@ static int do_one_pass(journal_t *journa
 436                         continue;
 437
 438                 case JFS_COMMIT_BLOCK:
 439 -                       /* Found an expected commit block: not much to
 440 -                        * do other than move on to the next sequence
 441 +                       /*     How to differentiate between interrupted commit
 442 +                        *               and journal corruption ?
 443 +                        *
 444 +                        * {nth transaction}
 445 +                        *        Checksum Verification Failed
 446 +                        *                       |
 447 +                        *               ____________________
 448 +                        *              |                    |
 449 +                        *      async_commit             sync_commit
 450 +                        *              |                    |
 451 +                        *              | GO TO NEXT    "Journal Corruption"
 452 +                        *              | TRANSACTION
 453 +                        *              |
 454 +                        * {(n+1)th transanction}
 455 +                        *              |
 456 +                        *       _______|______________
 457 +                        *      |                     |
 458 +                        * Commit block found   Commit block not found
 459 +                        *      |                     |
 460 +                        * "Journal Corruption"       |
 461 +                        *               _____________|__________
 462 +                        *              |                       |
 463 +                        *      nth trans corrupt       OR   nth trans
 464 +                        *      and (n+1)th interrupted     interrupted
 465 +                        *      before commit block
 466 +                        *      could reach the disk.
 467 +                        *      (Cannot find the difference in above
 468 +                        *       mentioned conditions. Hence assume
 469 +                        *       "Interrupted Commit".)
 470 +                        */
 471 +
 472 +                       /* Found an expected commit block: if checksums
 473 +                        * are present verify them in PASS_SCAN; else not
 474 +                        * much to do other than move on to the next sequence
 475                          * number. */
 476 +                       if (pass == PASS_SCAN &&
 477 +                           JFS_HAS_COMPAT_FEATURE(journal,
 478 +                                   JFS_FEATURE_COMPAT_CHECKSUM)) {
 479 +                               int chksum_err, chksum_seen;
 480 +                               struct commit_header *cbh =
 481 +                                       (struct commit_header *)bh->b_data;
 482 +                               unsigned found_chksum =
 483 +                                               be32_to_cpu(cbh->h_chksum[0]);
 484 +
 485 +                               chksum_err = chksum_seen = 0;
 486 +
 487 +                               if (info->end_transaction) {
 488 +                                       printk(KERN_ERR "JBD: Transaction %u "
 489 +                                               "found to be corrupt.\n",
 490 +                                               next_commit_ID - 1);
 491 +                                       brelse(bh);
 492 +                                       break;
 493 +                               }
 494 +
 495 +                               if (crc32_sum == found_chksum &&
 496 +                                   cbh->h_chksum_type == JFS_CRC32_CHKSUM &&
 497 +                                   cbh->h_chksum_size ==
 498 +                                               JFS_CRC32_CHKSUM_SIZE) {
 499 +                                      chksum_seen = 1;
 500 +                               } else if (!(cbh->h_chksum_type == 0 &&
 501 +                                            cbh->h_chksum_size == 0 &&
 502 +                                            found_chksum == 0 &&
 503 +                                            !chksum_seen)) {
 504 +                               /*
 505 +                                * If fs is mounted using an old kernel and then
 506 +                                * kernel with journal_chksum is used then we
 507 +                                * get a situation where the journal flag has
 508 +                                * checksum flag set but checksums are not
 509 +                                * present i.e chksum = 0, in the individual
 510 +                                * commit blocks.
 511 +                                * Hence to avoid checksum failures, in this
 512 +                                * situation, this extra check is added.
 513 +                                */
 514 +                                               chksum_err = 1;
 515 +                               }
 516 +
 517 +                               if (chksum_err) {
 518 +                                       info->end_transaction = next_commit_ID;
 519 +
 520 +                                       if (!JFS_HAS_COMPAT_FEATURE(journal,
 521 +                                           JFS_FEATURE_INCOMPAT_ASYNC_COMMIT)){
 522 +                                               printk(KERN_ERR
 523 +                                                      "JBD: Transaction %u "
 524 +                                                      "found to be corrupt.\n",
 525 +                                                      next_commit_ID);
 526 +                                               brelse(bh);
 527 +                                               break;
 528 +                                       }
 529 +                               }
 530 +                               crc32_sum = ~0;
 531 +                       }
 532                         brelse(bh);
 533                         next_commit_ID++;
 534                         continue;
 535 @@ -543,9 +679,10 @@ static int do_one_pass(journal_t *journa
 536          * transaction marks the end of the valid log.
 537          */
 538
 539 -       if (pass == PASS_SCAN)
 540 -               info->end_transaction = next_commit_ID;
 541 -       else {
 542 +       if (pass == PASS_SCAN) {
 543 +               if (!info->end_transaction)
 544 +                       info->end_transaction = next_commit_ID;
 545 +       } else {
 546                 /* It's really bad news if different passes end up at
 547                  * different places (but possible due to IO errors). */
 548                 if (info->end_transaction != next_commit_ID) {
 549 Index: linux-2.6.16.53-0.16/fs/jbd/journal.c
 550 ===================================================================
 551 --- linux-2.6.16.53-0.16.orig/fs/jbd/journal.c
 552 +++ linux-2.6.16.53-0.16/fs/jbd/journal.c
 553 @@ -64,6 +64,7 @@ EXPORT_SYMBOL(journal_update_format);
 554  EXPORT_SYMBOL(journal_check_used_features);
 555  EXPORT_SYMBOL(journal_check_available_features);
 556  EXPORT_SYMBOL(journal_set_features);
 557 +EXPORT_SYMBOL(journal_clear_features);
 558  EXPORT_SYMBOL(journal_create);
 559  EXPORT_SYMBOL(journal_load);
 560  EXPORT_SYMBOL(journal_destroy);
 561 @@ -1565,6 +1566,33 @@ int journal_set_features (journal_t *jou
 562         return 1;
 563  }
 564
 565 +/**
 566 + * int journal_clear_features () - Clear a given journal feature in the superblock
 567 + * @journal: Journal to act on.
 568 + * @compat: bitmask of compatible features
 569 + * @ro: bitmask of features that force read-only mount
 570 + * @incompat: bitmask of incompatible features
 571 + *
 572 + * Clear a given journal feature as present on the
 573 + * superblock.  Returns true if the requested features could be reset.
 574 + *
 575 + */
 576 +int journal_clear_features (journal_t *journal, unsigned long compat,
 577 +                         unsigned long ro, unsigned long incompat)
 578 +{
 579 +       journal_superblock_t *sb;
 580 +
 581 +       jbd_debug(1, "Clear features 0x%lx/0x%lx/0x%lx\n",
 582 +                 compat, ro, incompat);
 583 +
 584 +       sb = journal->j_superblock;
 585 +
 586 +       sb->s_feature_compat    &= ~cpu_to_be32(compat);
 587 +       sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
 588 +       sb->s_feature_incompat  &= ~cpu_to_be32(incompat);
 589 +
 590 +       return 1;
 591 +}
 592
 593  /**
 594   * int journal_update_format () - Update on-disk journal structure.
 595 Index: linux-2.6.16.53-0.16/fs/Kconfig
 596 ===================================================================
 597 --- linux-2.6.16.53-0.16.orig/fs/Kconfig
 598 +++ linux-2.6.16.53-0.16/fs/Kconfig
 599 @@ -140,6 +140,7 @@ config EXT3_FS_SECURITY
 600
 601  config JBD
 602         tristate
 603 +       select CRC32
 604         help
 605           This is a generic journaling layer for block devices.  It is
 606           currently used by the ext3 and OCFS2 file systems, but it could
 607 Index: linux-2.6.16.53-0.16/Documentation/filesystems/ext3.txt
 608 ===================================================================
 609 --- linux-2.6.16.53-0.16.orig/Documentation/filesystems/ext3.txt
 610 +++ linux-2.6.16.53-0.16/Documentation/filesystems/ext3.txt
 611 @@ -14,6 +14,16 @@ Options
 612  When mounting an ext3 filesystem, the following option are accepted:
 613  (*) == default
 614
 615 +journal_checksum       Enable checksumming of the journal transactions.
 616 +                       This will allow the recovery code in e2fsck and the
 617 +                       kernel to detect corruption in the kernel.  It is a
 618 +                       compatible change and will be ignored by older kernels.
 619 +
 620 +journal_async_commit   Commit block can be written to disk without waiting
 621 +                       for descriptor blocks. If enabled older kernels cannot
 622 +                       mount the device. This will enable 'journal_checksum'
 623 +                       internally.
 624 +
 625  journal=update         Update the ext3 file system's journal to the current
 626                         format.
 627