perform AIO-DIO and fcntl(F_SETFL) concurently. Unaligned AIO likely
results in synchronization which makes the race window wider.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>