If ocfs2_is_overwrite failed, ocfs2_direct_IO_write mays till return
success to the caller.
Signed-off-by: Norton.Zhu <norton.zhu@huawei.com> Cc: Mark Fasheh <mfasheh@suse.de> Cc: Joel Becker <jlbec@evilplan.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>