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

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

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);