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    Subject[09/34] ext4: fix possible recursive locking warning in EXT4_IOC_MOVE_EXT
    2.6.32-stable review patch.  If anyone has any objections, please let us know.

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

    (cherry picked from commit 49bd22bc4d603a2a4fc2a6a60e156cbea52eb494)

    If CONFIG_PROVE_LOCKING is enabled, the double_down_write_data_sem()
    will trigger a false-positive warning of a recursive lock. Since we
    take i_data_sem for the two inodes ordered by their inode numbers,
    this isn't a problem. Use of down_write_nested() will notify the lock
    dependency checker machinery that there is no problem here.

    This problem was reported by Brian Rogers:

    http://marc.info/?l=linux-ext4&m=125115356928011&w=1

    Reported-by: Brian Rogers <brian@xyzw.org>
    Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com>
    Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
    ---
    fs/ext4/move_extent.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/fs/ext4/move_extent.c
    +++ b/fs/ext4/move_extent.c
    @@ -189,7 +189,7 @@ double_down_write_data_sem(struct inode
    }

    down_write(&EXT4_I(first)->i_data_sem);
    - down_write(&EXT4_I(second)->i_data_sem);
    + down_write_nested(&EXT4_I(second)->i_data_sem, SINGLE_DEPTH_NESTING);
    }

    /**



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