ext4: release bh in make_indexed_dir

commit e81d44778d1d57bbaef9e24c4eac7c8a7a401d40 upstream.

The commit 6050d47a: "ext4: bail out from make_indexed_dir() on
first error" could end up leaking bh2 in the error path.

[ Also avoid renaming bh2 to bh, which just confuses things --tytso ]

Signed-off-by: yangsheng <yngsion@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>