Re: [PATCH v2] fs: Fix page cache inconsistency when mixing buffered and AIO DIO

[Jan Kara <jack@suse.cz>]

On Tue 18-07-17 09:39:35, Lukas Czerner wrote:
> On Mon, Jul 17, 2017 at 11:39:09AM -0400, Jeff Moyer wrote:
> > Lukas Czerner <lczerner@redhat.com> writes:
> > 
> > > About the error case, is it not possible that some data has already been
> > > writtent to the disk despite the error ?
> > 
> > Yes, it's possible.  However, that data is in an inconsistent state, so
> > it shouldn't be read, anyway.
> 
> I think it can be read if we wrote into already allocated space.
> 
> > 
> > Now, in the non-async path, we do the invalidation unconditionally, so I
> > could go either way on this.  I don't think it's going to matter for
> > performance or data integrity.
> 
> That's part of the reason why I did it unconditionaly as well, however
> Jan is right that ret would be negative. The way to fix it would differ
> depending on whether I am right about reading partially written data
> from AIO that failed. We still want to invalidate in that case.

Frankly, I don't think it really matters so I'd go for not invalidating
anything on error just out of philosophy: "There's something weird going
on, bail out as quickly as you can."

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