ext4_truncate_block_allocated_on_a_failed_ext4_write_begin.patch

   1 ext4: truncate block allocated on a failed ext4_write_begin
   2
   3 From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   4
   5 For blocksize < pagesize we need to remove blocks that got allocated in
   6 block_write_begin() if we fail with ENOSPC for later blocks.
   7 block_write_begin() internally does this if it allocated page
   8 locally. This makes sure we don't have blocks outside inode.i_size
   9 during ENOSPC.
  10
  11 Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
  12 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  13
  14 diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
  15 index 5a595af..6cfe142 100644
  16 --- a/fs/ext4/inode.c
  17 +++ b/fs/ext4/inode.c
  18 @@ -1391,6 +1391,13 @@ retry:
  19                 unlock_page(page);
  20                 ext4_journal_stop(handle);
  21                 page_cache_release(page);
  22 +               /*
  23 +                * block_write_begin may have instantiated a few blocks
  24 +                * outside i_size.  Trim these off again. Don't need
  25 +                * i_size_read because we hold i_mutex.
  26 +                */
  27 +               if (pos + len > inode->i_size)
  28 +                       vmtruncate(inode, inode->i_size);
  29         }
  30
  31         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))