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 pages locally.
   8 This makes sure we don't have blocks outside inode.i_size during ENOSPC.
   9
  10 Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
  11 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  12 diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
  13 index 5a595af..a1e235d 100644
  14 --- a/fs/ext4/inode.c
  15 +++ b/fs/ext4/inode.c
  16 @@ -1391,6 +1391,13 @@ retry:
  17                 unlock_page(page);
  18                 ext4_journal_stop(handle);
  19                 page_cache_release(page);
  20 +               /*
  21 +                * block_write_begin may have instantiated a few blocks
  22 +                * outside i_size.  Trim these off again. Don't need
  23 +                * i_size_read because we hold i_mutex.
  24 +                */
  25 +               if (pos + len > inode->i_size)
  26 +                       vmtruncate(inode, inode->i_size);
  27         }
  28
  29         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
  30 @@ -2560,6 +2567,13 @@ retry:
  31                 unlock_page(page);
  32                 ext4_journal_stop(handle);
  33                 page_cache_release(page);
  34 +               /*
  35 +                * block_write_begin may have instantiated a few blocks
  36 +                * outside i_size.  Trim these off again. Don't need
  37 +                * i_size_read because we hold i_mutex.
  38 +                */
  39 +               if (pos + len > inode->i_size)
  40 +                       vmtruncate(inode, inode->i_size);
  41         }
  42
  43         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))