[Cluster-devel] RFC: iomap write invalidation

[Christoph Hellwig]

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.