[PATCH 3.16 074/233] ext4: keep existing extra fields when inode expands

[Ben Hutchings]

3.16.48-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Konstantin Khlebnikov <khlebni...@yandex-team.ru>

commit 887a9730614727c4fff7cb756711b190593fc1df upstream.

ext4_expand_extra_isize() should clear only space between old and new
size.

Fixes: 6dd4ee7cab7e # v2.6.23
Signed-off-by: Konstantin Khlebnikov <khlebni...@yandex-team.ru>
Signed-off-by: Theodore Ts'o <ty...@mit.edu>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 fs/ext4/inode.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5055,8 +5055,9 @@ static int ext4_expand_extra_isize(struc
        /* No extended attributes present */
        if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR) ||
            header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) {
-               memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE, 0,
-                       new_extra_isize);
+               memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE +
+                      EXT4_I(inode)->i_extra_isize, 0,
+                      new_extra_isize - EXT4_I(inode)->i_extra_isize);
                EXT4_I(inode)->i_extra_isize = new_extra_isize;
                return 0;
        }