Re: [PATCH 4/5] ceph: fix improper use of smp_mb__before_atomic()

Andrea Parri
2019-05-09T20:55:55Z

On Tue, Apr 30, 2019 at 05:08:43PM +0800, Yan, Zheng wrote:
> On Tue, Apr 30, 2019 at 4:26 PM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > On Mon, Apr 29, 2019 at 10:15:00PM +0200, Andrea Parri wrote:
> > > This barrier only applies to the read-modify-write operations; in
> > > particular, it does not apply to the atomic64_set() primitive.
> > >
> > > Replace the barrier with an smp_mb().
> > >
> >
> > > @@ -541,7 +541,7 @@ static inline void __ceph_dir_set_complete(struct ceph_inode_info *ci,
> > > long long release_count,
> > > long long ordered_count)
> > > {
> > > - smp_mb__before_atomic();
> >
> > same
> > /*
> > * XXX: the comment that explain this barrier goes here.
> > */
> >
>
> makes sure operations that setup readdir cache (update page cache and
> i_size) are strongly ordered with following atomic64_set.

Thanks for the suggestion, Yan.

To be clear: would you like me to integrate your comment and resend?
any other suggestions?

Thanx,
Andrea

>
> > > + smp_mb();
> >
> > > atomic64_set(&ci->i_complete_seq[0], release_count);
> > > atomic64_set(&ci->i_complete_seq[1], ordered_count);
> > > }
> > > --
> > > 2.7.4
> > >