releases/2.6.32.17/0006-ext4-Ensure-zeroout-blocks-have-no-dirty-metadata.patch

   1 From 436e2704a8b589fb1217add4f9e5be480773ca6c Mon Sep 17 00:00:00 2001
   2 From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   3 Date: Sun, 30 May 2010 22:49:20 -0400
   4 Subject: ext4: Ensure zeroout blocks have no dirty metadata
   5
   6 commit 515f41c33a9d44a964264c9511ad2c869af1fac3 upstream (as of v2.6.33-rc3)
   7
   8 This fixes a bug (found by Curt Wohlgemuth) in which new blocks
   9 returned from an extent created with ext4_ext_zeroout() can have dirty
  10 metadata still associated with them.
  11
  12 Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
  13 Signed-off-by: Curt Wohlgemuth <curtw@google.com>
  14 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  15 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  16 ---
  17  fs/ext4/extents.c |   20 ++++++++++++++++++++
  18  1 file changed, 20 insertions(+)
  19
  20 --- a/fs/ext4/extents.c
  21 +++ b/fs/ext4/extents.c
  22 @@ -3029,6 +3029,14 @@ out:
  23         return err;
  24  }
  25
  26 +static void unmap_underlying_metadata_blocks(struct block_device *bdev,
  27 +                       sector_t block, int count)
  28 +{
  29 +       int i;
  30 +       for (i = 0; i < count; i++)
  31 +                unmap_underlying_metadata(bdev, block + i);
  32 +}
  33 +
  34  static int
  35  ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
  36                         ext4_lblk_t iblock, unsigned int max_blocks,
  37 @@ -3104,6 +3112,18 @@ out:
  38         } else
  39                 allocated = ret;
  40         set_buffer_new(bh_result);
  41 +       /*
  42 +        * if we allocated more blocks than requested
  43 +        * we need to make sure we unmap the extra block
  44 +        * allocated. The actual needed block will get
  45 +        * unmapped later when we find the buffer_head marked
  46 +        * new.
  47 +        */
  48 +       if (allocated > max_blocks) {
  49 +               unmap_underlying_metadata_blocks(inode->i_sb->s_bdev,
  50 +                                       newblock + max_blocks,
  51 +                                       allocated - max_blocks);
  52 +       }
  53  map_out:
  54         set_buffer_mapped(bh_result);
  55  out1: