fix-unjournaled-bg-descriptor-while-initializing-inode-bitmap

   1 ext4: fix unjournalled bg descriptor while initializing inode bitmap
   2
   3 The first time that we allocate from an uninitialized inode allocation
   4 bitmap, if the block allocation bitmap is also uninitalized, we need
   5 to get write access to the block group descriptor before we start
   6 modifying the block group descriptor flags and updating the free block
   7 count, etc.  Otherwise, there is the potential of a bad journal
   8 checksum (if journal checksums are enabled), and of the file system
   9 becoming inconsistent if we crash at exactly the wrong time.
  10
  11 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  12 Cc: stable@vger.kernel.org
  13 ---
  14  fs/ext4/ialloc.c | 14 +++++++-------
  15  1 file changed, 7 insertions(+), 7 deletions(-)
  16
  17 diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
  18 index a87455d..0840bf3 100644
  19 --- a/fs/ext4/ialloc.c
  20 +++ b/fs/ext4/ialloc.c
  21 @@ -874,6 +874,13 @@ got:
  22                 goto out;
  23         }
  24
  25 +       BUFFER_TRACE(group_desc_bh, "get_write_access");
  26 +       err = ext4_journal_get_write_access(handle, group_desc_bh);
  27 +       if (err) {
  28 +               ext4_std_error(sb, err);
  29 +               goto out;
  30 +       }
  31 +
  32         /* We may have to initialize the block bitmap if it isn't already */
  33         if (ext4_has_group_desc_csum(sb) &&
  34             gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
  35 @@ -910,13 +917,6 @@ got:
  36                 }
  37         }
  38
  39 -       BUFFER_TRACE(group_desc_bh, "get_write_access");
  40 -       err = ext4_journal_get_write_access(handle, group_desc_bh);
  41 -       if (err) {
  42 -               ext4_std_error(sb, err);
  43 -               goto out;
  44 -       }
  45 -
  46         /* Update the relevant bg descriptor fields */
  47         if (ext4_has_group_desc_csum(sb)) {
  48                 int free;