Re: RFC: iomap write invalidation

Matthew Wilcox
2020-07-21T15:52:08Z

On Tue, Jul 21, 2020 at 05:42:40PM +0200, Christoph Hellwig wrote:
> On Tue, Jul 21, 2020 at 04:31:36PM +0100, Matthew Wilcox wrote:
> > > Umm, no. -ENOTBLK is internal - the file systems will retry using
> > > buffered I/O and the error shall never escape to userspace (or even the
> > > VFS for that matter).
> >
> > Ah, I made the mistake of believing the comments that I could see in
> > your patch instead of reading the code.
> >
> > Can I suggest deleting this comment:
> >
> > /*
> > * No fallback to buffered IO on errors for XFS, direct IO will either
> > * complete fully or fail.
> > */
> >
> > and rewording this one:
> >
> > /*
> > * Allow a directio write to fall back to a buffered
> > * write *only* in the case that we're doing a reflink
> > * CoW. In all other directio scenarios we do not
> > * allow an operation to fall back to buffered mode.
> > */
> >
> > as part of your revised patchset?
>
> That isn't actually true. In current mainline we only fallback on
> reflink RMW cases, but with this series we also fall back for
> invalidation failures.

... that's why I'm suggesting that you delete the first one and rewrite
the second one. Because they aren't true.