Re: RFC: iomap write invalidation

Matthew Wilcox
2020-07-21T15:31:43Z

On Tue, Jul 21, 2020 at 05:16:16PM +0200, Christoph Hellwig wrote:
> On Tue, Jul 21, 2020 at 04:14:37PM +0100, Matthew Wilcox wrote:
> > On Tue, Jul 21, 2020 at 05:06:15PM +0200, Christoph Hellwig wrote:
> > > On Tue, Jul 21, 2020 at 04:04:32PM +0100, Matthew Wilcox wrote:
> > > > I thought you were going to respin this with EREMCHG changed to ENOTBLK?
> > >
> > > Oh, true. I'll do that ASAP.
> >
> > Michael, could we add this to manpages?
>
> 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?