Re: [PATCH v2 1/3] mm: kick writeback flusher instead of inline flush for IOCB_DONTCACHE

Jan Kara
2026-04-10T10:41:50Z

On Thu 09-04-26 07:21:22, Christoph Hellwig wrote:
> On Thu, Apr 09, 2026 at 09:21:36AM +0200, Jan Kara wrote:
> > > So I think you'll want a new WB_start_dontcache bit, a new
> > > get_nr_dontcache_pages() helper on a new node counter, etc.
> >
> > But I'm not sure how you imagine this would work without restricting
> > writeback to particular inodes. Maybe we could mark inodes which have
> > folios with dropbehind set and make flush worker only write such inodes?
>
> I'd only expedite writing by the number of pending dontcache folios.
> It would still write the least recently dirtied inodes.

So that may result in dontcache folios staying cached for quite some time
if DONTCACHE and normal writes are mixed. But I agree over longer time it
might just level out so maybe that's fine.

Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR