On Tue 02-05-23 13:13:34, Peter Zijlstra wrote:
> On Tue, May 02, 2023 at 12:11:49AM +0100, Lorenzo Stoakes wrote:
> > +
> > + /*
> > + * Neither anonymous nor shmem-backed folios require
> > + * dirty tracking.
> > + */
> > + ret = folio_test_anon(folio) ||
> > + (mapping && shmem_mapping(mapping));
> > + } else {
> > + /* If the mapping is unstable, fallback to the slow path. */
> > + ret = false;
> > + }
> > +
> > + unlock_rcu();
> > +
> > + return ret;
>
> then becomes:
>
>
> if (folio_test_anon(folio))
> return true;
>
> /*
> * Having IRQs disabled (as per GUP-fast) also inhibits RCU
> * grace periods from making progress, IOW. they imply
> * rcu_read_lock().
> */
> lockdep_assert_irqs_disabled();
>
> /*
> * Inodes and thus address_space are RCU freed and thus safe to
> * access at this point.
> */
> mapping = folio_mapping(folio);
> if (mapping && shmem_mapping(mapping))
> return true;
>
> return false;
Yeah, that's even better.
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
