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

   1 Index: linux-2.6.16.46-0.14/fs/jbd/commit.c
   2 ===================================================================
   3 --- linux-2.6.16.46-0.14.orig/fs/jbd/commit.c
   4 +++ linux-2.6.16.46-0.14/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 @@ -153,15 +171,74 @@ 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 +
 160 +/*
 161   * journal_commit_transaction
 162   *
 163   * The primary function for committing a transaction to the log.  This
 164 @@ -184,6 +261,8 @@ void journal_commit_transaction(journal_
 165         int first_tag = 0;
 166         int tag_flag;
 167         int i;
 168 +       struct buffer_head *cbh = NULL; /* For transactional checksums */
 169 +       __u32 crc32_sum = ~0;
 170
 171         /*
 172          * First job: lock down the current transaction and wait for
 173 @@ -395,37 +474,14 @@ write_out_data:
 174         }
 175
 176         /*
 177 -        * Wait for all previously submitted IO to complete.
 178 +        * Wait for all previously submitted IO to complete if commit
 179 +        * record is to be written synchronously.
 180          */
 181 -       while (commit_transaction->t_locked_list) {
 182 -               struct buffer_head *bh;
 183 +       if (!JFS_HAS_INCOMPAT_FEATURE(journal,
 184 +               JFS_FEATURE_INCOMPAT_ASYNC_COMMIT))
 185 +               err = journal_wait_on_locked_list(journal,
 186 +                                                 commit_transaction);
 187
 188 -               jh = commit_transaction->t_locked_list->b_tprev;
 189 -               bh = jh2bh(jh);
 190 -               get_bh(bh);
 191 -               if (buffer_locked(bh)) {
 192 -                       spin_unlock(&journal->j_list_lock);
 193 -                       wait_on_buffer(bh);
 194 -                       if (unlikely(!buffer_uptodate(bh)))
 195 -                               err = -EIO;
 196 -                       spin_lock(&journal->j_list_lock);
 197 -               }
 198 -               if (!inverted_lock(journal, bh)) {
 199 -                       put_bh(bh);
 200 -                       spin_lock(&journal->j_list_lock);
 201 -                       continue;
 202 -               }
 203 -               if (buffer_jbd(bh) && jh->b_jlist == BJ_Locked) {
 204 -                       __journal_unfile_buffer(jh);
 205 -                       jbd_unlock_bh_state(bh);
 206 -                       journal_remove_journal_head(bh);
 207 -                       put_bh(bh);
 208 -               } else {
 209 -                       jbd_unlock_bh_state(bh);
 210 -               }
 211 -               put_bh(bh);
 212 -               cond_resched_lock(&journal->j_list_lock);
 213 -       }
 214         spin_unlock(&journal->j_list_lock);
 215
 216         if (err)
 217 @@ -598,6 +654,16 @@ write_out_data:
 218  start_journal_io:
 219                         for (i = 0; i < bufs; i++) {
 220                                 struct buffer_head *bh = wbuf[i];
 221 +                               /*
 222 +                                * Compute checksum.
 223 +                                */
 224 +                               if (JFS_HAS_COMPAT_FEATURE(journal,
 225 +                                       JFS_FEATURE_COMPAT_CHECKSUM)) {
 226 +                                       crc32_sum = crc32_be(crc32_sum,
 227 +                                                       (void *)bh->b_data,
 228 +                                                       bh->b_size);
 229 +                               }
 230 +
 231                                 lock_buffer(bh);
 232                                 clear_buffer_dirty(bh);
 233                                 set_buffer_uptodate(bh);
 234 @@ -614,6 +680,23 @@ start_journal_io:
 235                 }
 236         }
 237
 238 +       /* Done it all: now write the commit record asynchronously. */
 239 +
 240 +       if (JFS_HAS_INCOMPAT_FEATURE(journal,
 241 +               JFS_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
 242 +               err = journal_submit_commit_record(journal, commit_transaction,
 243 +                                                &cbh, crc32_sum);
 244 +               if (err)
 245 +                       __journal_abort_hard(journal);
 246 +
 247 +               spin_lock(&journal->j_list_lock);
 248 +               err = journal_wait_on_locked_list(journal,
 249 +                                               commit_transaction);
 250 +               spin_unlock(&journal->j_list_lock);
 251 +               if (err)
 252 +                       __journal_abort_hard(journal);
 253 +       }
 254 +
 255         /* Lo and behold: we have just managed to send a transaction to
 256             the log.  Before we can commit it, wait for the IO so far to
 257             complete.  Control buffers being written are on the
 258 @@ -712,9 +795,15 @@ wait_for_iobuf:
 259         }
 260
 261         jbd_debug(3, "JBD: commit phase 6\n");
 262 -
 263 -       if (journal_write_commit_record(journal, commit_transaction))
 264 -               err = -EIO;
 265 +
 266 +       if (!JFS_HAS_INCOMPAT_FEATURE(journal,
 267 +               JFS_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
 268 +               err = journal_submit_commit_record(journal, commit_transaction,
 269 +                                               &cbh, crc32_sum);
 270 +               if (err)
 271 +                       __journal_abort_hard(journal);
 272 +       }
 273 +       err = journal_wait_on_commit_record(cbh);
 274
 275         if (err)
 276                 __journal_abort_hard(journal);
 277 Index: linux-2.6.16.46-0.14/include/linux/jbd.h
 278 ===================================================================
 279 --- linux-2.6.16.46-0.14.orig/include/linux/jbd.h
 280 +++ linux-2.6.16.46-0.14/include/linux/jbd.h
 281 @@ -142,6 +142,29 @@ typedef struct journal_header_s
 282         __be32          h_sequence;
 283  } journal_header_t;
 284
 285 +/*
 286 + * Checksum types.
 287 + */
 288 +#define JFS_CRC32_CHKSUM   1
 289 +#define JFS_MD5_CHKSUM     2
 290 +#define JFS_SHA1_CHKSUM    3
 291 +
 292 +#define JFS_CRC32_CHKSUM_SIZE 4
 293 +
 294 +#define JFS_CHECKSUM_BYTES (32 / sizeof(u32))
 295 +/*
 296 + * Commit block header for storing transactional checksums:
 297 + */
 298 +struct commit_header
 299 +{
 300 +       __be32          h_magic;
 301 +       __be32          h_blocktype;
 302 +       __be32          h_sequence;
 303 +       unsigned char   h_chksum_type;
 304 +       unsigned char   h_chksum_size;
 305 +       unsigned char   h_padding[2];
 306 +       __be32          h_chksum[JFS_CHECKSUM_BYTES];
 307 +};
 308
 309  /*
 310   * The block tag: used to describe a single buffer in the journal
 311 @@ -228,12 +251,16 @@ typedef struct journal_superblock_s
 312         ((j)->j_format_version >= 2 &&                                  \
 313          ((j)->j_superblock->s_feature_incompat & cpu_to_be32((mask))))
 314
 315 -#define JFS_FEATURE_INCOMPAT_REVOKE    0x00000001
 316 +#define JFS_FEATURE_COMPAT_CHECKSUM    0x00000001
 317 +
 318 +#define JFS_FEATURE_INCOMPAT_REVOKE            0x00000001
 319 +#define JFS_FEATURE_INCOMPAT_ASYNC_COMMIT      0x00000004
 320
 321  /* Features known to this kernel version: */
 322 -#define JFS_KNOWN_COMPAT_FEATURES      0
 323 +#define JFS_KNOWN_COMPAT_FEATURES      JFS_FEATURE_COMPAT_CHECKSUM
 324  #define JFS_KNOWN_ROCOMPAT_FEATURES    0
 325 -#define JFS_KNOWN_INCOMPAT_FEATURES    JFS_FEATURE_INCOMPAT_REVOKE
 326 +#define JFS_KNOWN_INCOMPAT_FEATURES    JFS_FEATURE_INCOMPAT_REVOKE | \
 327 +                                       JFS_FEATURE_INCOMPAT_ASYNC_COMMIT
 328
 329  #ifdef __KERNEL__
 330
 331 @@ -1041,6 +1068,8 @@ extern int           journal_check_available_fe
 332                    (journal_t *, unsigned long, unsigned long, unsigned long);
 333  extern int        journal_set_features
 334                    (journal_t *, unsigned long, unsigned long, unsigned long);
 335 +extern int        journal_clear_features
 336 +                  (journal_t *, unsigned long, unsigned long, unsigned long);
 337  extern int        journal_create     (journal_t *);
 338  extern int        journal_load       (journal_t *journal);
 339  extern void       journal_destroy    (journal_t *);
 340 Index: linux-2.6.16.46-0.14/fs/jbd/recovery.c
 341 ===================================================================
 342 --- linux-2.6.16.46-0.14.orig/fs/jbd/recovery.c
 343 +++ linux-2.6.16.46-0.14/fs/jbd/recovery.c
 344 @@ -21,6 +21,7 @@
 345  #include <linux/jbd.h>
 346  #include <linux/errno.h>
 347  #include <linux/slab.h>
 348 +#include <linux/crc32.h>
 349  #endif
 350
 351  /*
 352 @@ -307,6 +308,37 @@ int journal_skip_recovery(journal_t *jou
 353         return err;
 354  }
 355
 356 +/*
 357 + * calc_chksums calculates the checksums for the blocks described in the
 358 + * descriptor block.
 359 + */
 360 +static int calc_chksums(journal_t *journal, struct buffer_head *bh,
 361 +                      unsigned long *next_log_block, __u32 *crc32_sum)
 362 +{
 363 +       int i, num_blks, err;
 364 +       unsigned io_block;
 365 +       struct buffer_head *obh;
 366 +
 367 +       num_blks = count_tags(bh, journal->j_blocksize);
 368 +       /* Calculate checksum of the descriptor block. */
 369 +       *crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
 370 +
 371 +       for (i = 0; i < num_blks; i++) {
 372 +               io_block = (*next_log_block)++;
 373 +               wrap(journal, *next_log_block);
 374 +               err = jread(&obh, journal, io_block);
 375 +               if (err) {
 376 +                       printk(KERN_ERR "JBD: IO error %d recovering block "
 377 +                               "%u in log\n", err, io_block);
 378 +                       return 1;
 379 +               } else {
 380 +                       *crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
 381 +                                    obh->b_size);
 382 +               }
 383 +       }
 384 +       return 0;
 385 +}
 386 +
 387  static int do_one_pass(journal_t *journal,
 388                         struct recovery_info *info, enum passtype pass)
 389  {
 390 @@ -318,6 +350,7 @@ static int do_one_pass(journal_t *journa
 391         struct buffer_head *    bh;
 392         unsigned int            sequence;
 393         int                     blocktype;
 394 +       __u32                   crc32_sum = ~0; /* Transactional Checksums */
 395
 396         /* Precompute the maximum metadata descriptors in a descriptor block */
 397         int                     MAX_BLOCKS_PER_DESC;
 398 @@ -409,9 +442,24 @@ static int do_one_pass(journal_t *journa
 399                 switch(blocktype) {
 400                 case JFS_DESCRIPTOR_BLOCK:
 401                         /* If it is a valid descriptor block, replay it
 402 -                        * in pass REPLAY; otherwise, just skip over the
 403 -                        * blocks it describes. */
 404 +                        * in pass REPLAY; if journal_checksums enabled, then
 405 +                        * calculate checksums in PASS_SCAN, otherwise,
 406 +                        * just skip over the blocks it describes. */
 407                         if (pass != PASS_REPLAY) {
 408 +                               if (pass == PASS_SCAN &&
 409 +                                   JFS_HAS_COMPAT_FEATURE(journal,
 410 +                                           JFS_FEATURE_COMPAT_CHECKSUM) &&
 411 +                                   !info->end_transaction) {
 412 +                                       if (calc_chksums(journal, bh,
 413 +                                                       &next_log_block,
 414 +                                                       &crc32_sum)) {
 415 +                                               brelse(bh);
 416 +                                               break;
 417 +                                       }
 418 +                                       brelse(bh);
 419 +                                       continue;
 420 +                               }
 421 +
 422                                 next_log_block +=
 423                                         count_tags(bh, journal->j_blocksize);
 424                                 wrap(journal, next_log_block);
 425 @@ -506,9 +554,97 @@ static int do_one_pass(journal_t *journa
 426                         continue;
 427
 428                 case JFS_COMMIT_BLOCK:
 429 -                       /* Found an expected commit block: not much to
 430 -                        * do other than move on to the next sequence
 431 +                       /*     How to differentiate between interrupted commit
 432 +                        *               and journal corruption ?
 433 +                        *
 434 +                        * {nth transaction}
 435 +                        *        Checksum Verification Failed
 436 +                        *                       |
 437 +                        *               ____________________
 438 +                        *              |                    |
 439 +                        *      async_commit             sync_commit
 440 +                        *              |                    |
 441 +                        *              | GO TO NEXT    "Journal Corruption"
 442 +                        *              | TRANSACTION
 443 +                        *              |
 444 +                        * {(n+1)th transanction}
 445 +                        *              |
 446 +                        *       _______|______________
 447 +                        *      |                     |
 448 +                        * Commit block found   Commit block not found
 449 +                        *      |                     |
 450 +                        * "Journal Corruption"       |
 451 +                        *               _____________|__________
 452 +                        *              |                       |
 453 +                        *      nth trans corrupt       OR   nth trans
 454 +                        *      and (n+1)th interrupted     interrupted
 455 +                        *      before commit block
 456 +                        *      could reach the disk.
 457 +                        *      (Cannot find the difference in above
 458 +                        *       mentioned conditions. Hence assume
 459 +                        *       "Interrupted Commit".)
 460 +                        */
 461 +
 462 +                       /* Found an expected commit block: if checksums
 463 +                        * are present verify them in PASS_SCAN; else not
 464 +                        * much to do other than move on to the next sequence
 465                          * number. */
 466 +                       if (pass == PASS_SCAN &&
 467 +                           JFS_HAS_COMPAT_FEATURE(journal,
 468 +                                   JFS_FEATURE_COMPAT_CHECKSUM)) {
 469 +                               int chksum_err, chksum_seen;
 470 +                               struct commit_header *cbh =
 471 +                                       (struct commit_header *)bh->b_data;
 472 +                               unsigned found_chksum =
 473 +                                               be32_to_cpu(cbh->h_chksum[0]);
 474 +
 475 +                               chksum_err = chksum_seen = 0;
 476 +
 477 +                               if (info->end_transaction) {
 478 +                                       printk(KERN_ERR "JBD: Transaction %u "
 479 +                                               "found to be corrupt.\n",
 480 +                                               next_commit_ID - 1);
 481 +                                       brelse(bh);
 482 +                                       break;
 483 +                               }
 484 +
 485 +                               if (crc32_sum == found_chksum &&
 486 +                                   cbh->h_chksum_type == JFS_CRC32_CHKSUM &&
 487 +                                   cbh->h_chksum_size ==
 488 +                                               JFS_CRC32_CHKSUM_SIZE) {
 489 +                                      chksum_seen = 1;
 490 +                               } else if (!(cbh->h_chksum_type == 0 &&
 491 +                                            cbh->h_chksum_size == 0 &&
 492 +                                            found_chksum == 0 &&
 493 +                                            !chksum_seen)) {
 494 +                               /*
 495 +                                * If fs is mounted using an old kernel and then
 496 +                                * kernel with journal_chksum is used then we
 497 +                                * get a situation where the journal flag has
 498 +                                * checksum flag set but checksums are not
 499 +                                * present i.e chksum = 0, in the individual
 500 +                                * commit blocks.
 501 +                                * Hence to avoid checksum failures, in this
 502 +                                * situation, this extra check is added.
 503 +                                */
 504 +                                               chksum_err = 1;
 505 +                               }
 506 +
 507 +                               if (chksum_err) {
 508 +                                       info->end_transaction = next_commit_ID;
 509 +
 510 +                                       if (!JFS_HAS_COMPAT_FEATURE(journal,
 511 +                                           JFS_FEATURE_INCOMPAT_ASYNC_COMMIT)){
 512 +                                               printk(KERN_ERR
 513 +                                                      "JBD: Transaction %u "
 514 +                                                      "found to be corrupt.\n",
 515 +                                                      next_commit_ID);
 516 +                                               brelse(bh);
 517 +                                               break;
 518 +                                       }
 519 +                               }
 520 +                               crc32_sum = ~0;
 521 +                       }
 522                         brelse(bh);
 523                         next_commit_ID++;
 524                         continue;
 525 @@ -543,9 +679,10 @@ static int do_one_pass(journal_t *journa
 526          * transaction marks the end of the valid log.
 527          */
 528
 529 -       if (pass == PASS_SCAN)
 530 -               info->end_transaction = next_commit_ID;
 531 -       else {
 532 +       if (pass == PASS_SCAN) {
 533 +               if (!info->end_transaction)
 534 +                       info->end_transaction = next_commit_ID;
 535 +       } else {
 536                 /* It's really bad news if different passes end up at
 537                  * different places (but possible due to IO errors). */
 538                 if (info->end_transaction != next_commit_ID) {
 539 Index: linux-2.6.16.46-0.14/fs/jbd/journal.c
 540 ===================================================================
 541 --- linux-2.6.16.46-0.14.orig/fs/jbd/journal.c
 542 +++ linux-2.6.16.46-0.14/fs/jbd/journal.c
 543 @@ -64,6 +64,7 @@ EXPORT_SYMBOL(journal_update_format);
 544  EXPORT_SYMBOL(journal_check_used_features);
 545  EXPORT_SYMBOL(journal_check_available_features);
 546  EXPORT_SYMBOL(journal_set_features);
 547 +EXPORT_SYMBOL(journal_clear_features);
 548  EXPORT_SYMBOL(journal_create);
 549  EXPORT_SYMBOL(journal_load);
 550  EXPORT_SYMBOL(journal_destroy);
 551 @@ -1565,6 +1566,33 @@ int journal_set_features (journal_t *jou
 552         return 1;
 553  }
 554
 555 +/**
 556 + * int journal_clear_features () - Clear a given journal feature in the superblock
 557 + * @journal: Journal to act on.
 558 + * @compat: bitmask of compatible features
 559 + * @ro: bitmask of features that force read-only mount
 560 + * @incompat: bitmask of incompatible features
 561 + *
 562 + * Clear a given journal feature as present on the
 563 + * superblock.  Returns true if the requested features could be reset.
 564 + *
 565 + */
 566 +int journal_clear_features (journal_t *journal, unsigned long compat,
 567 +                         unsigned long ro, unsigned long incompat)
 568 +{
 569 +       journal_superblock_t *sb;
 570 +
 571 +       jbd_debug(1, "Clear features 0x%lx/0x%lx/0x%lx\n",
 572 +                 compat, ro, incompat);
 573 +
 574 +       sb = journal->j_superblock;
 575 +
 576 +       sb->s_feature_compat    &= ~cpu_to_be32(compat);
 577 +       sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
 578 +       sb->s_feature_incompat  &= ~cpu_to_be32(incompat);
 579 +
 580 +       return 1;
 581 +}
 582
 583  /**
 584   * int journal_update_format () - Update on-disk journal structure.
 585 Index: linux-2.6.16.46-0.14/fs/Kconfig
 586 ===================================================================
 587 --- linux-2.6.16.46-0.14.orig/fs/Kconfig
 588 +++ linux-2.6.16.46-0.14/fs/Kconfig
 589 @@ -140,6 +140,7 @@ config EXT3_FS_SECURITY
 590
 591  config JBD
 592         tristate
 593 +       select CRC32
 594         help
 595           This is a generic journaling layer for block devices.  It is
 596           currently used by the ext3 and OCFS2 file systems, but it could
 597 Index: linux-2.6.16.46-0.14/Documentation/filesystems/ext3.txt
 598 ===================================================================
 599 --- linux-2.6.16.46-0.14.orig/Documentation/filesystems/ext3.txt
 600 +++ linux-2.6.16.46-0.14/Documentation/filesystems/ext3.txt
 601 @@ -14,6 +14,16 @@ Options
 602  When mounting an ext3 filesystem, the following option are accepted:
 603  (*) == default
 604
 605 +journal_checksum       Enable checksumming of the journal transactions.
 606 +                       This will allow the recovery code in e2fsck and the
 607 +                       kernel to detect corruption in the kernel.  It is a
 608 +                       compatible change and will be ignored by older kernels.
 609 +
 610 +journal_async_commit   Commit block can be written to disk without waiting
 611 +                       for descriptor blocks. If enabled older kernels cannot
 612 +                       mount the device. This will enable 'journal_checksum'
 613 +                       internally.
 614 +
 615  journal=update         Update the ext3 file system's journal to the current
 616                         format.
 617