Re: [PATCH v5 7/9] iomap/xfs: Eliminate the iomap_valid handler

Christoph Hellwig
2023-01-08T17:32:45Z

On Wed, Jan 04, 2023 at 07:08:17PM +0000, Matthew Wilcox wrote:
> On Wed, Jan 04, 2023 at 09:53:17AM -0800, Darrick J. Wong wrote:
> > I wonder if this should be reworked a bit to reduce indenting:
> >
> > if (PTR_ERR(folio) == -ESTALE) {
>
> FYI this is a bad habit to be in. The compiler can optimise
>
> if (folio == ERR_PTR(-ESTALE))
>
> better than it can optimise the other way around.

Yes. I think doing the recording that Darrick suggested combined
with this style would be best:

if (folio == ERR_PTR(-ESTALE)) {
iter->iomap.flags |= IOMAP_F_STALE;
return 0;
}
if (IS_ERR(folio))
return PTR_ERR(folio);