On Tue, Jun 05, 2018 at 02:10:24PM +0200, David Sterba wrote:
> On Mon, Jun 04, 2018 at 09:31:16PM +0200, Andreas Gruenbacher wrote:
> > @@ -1062,8 +1063,9 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
> > if (ret < 0)
> > iomap_dio_set_error(dio, ret);
> >
> > + smp_mb__before_atomic();
> > if (!atomic_dec_and_test(&dio->ref)) {
>
> The barrier should be documented. I tried to do a quick look around the
> code if it's clear why it's there but it's not. Thanks.
It doesn't really make sense. smp_mb__before_atomic is for relaxed
atomic operations, which atomic_dec_and_test is not.
