Re: [PATCH v8 06/10] iomap: fix iomap_dio_zero() for fs bs > system page size

Christoph Hellwig
2024-07-02T12:02:58Z

On Tue, Jul 02, 2024 at 10:15:56AM +0000, Pankaj Raghav (Samsung) wrote:
> Willy suggested we could use raw pages as we don't need the metadata
> from using a folio. [0]

Ok, that feels weird but I'll defer to his opinion in that case.

> > > + /*
> > > + * Max block size supported is 64k
> > > + */
> > > + WARN_ON_ONCE(len > ZERO_PAGE_64K_SIZE);
> >
> >
> > A WARN_ON without actually erroring out here is highly dangerous.
>
> I agree but I think we decided that we are safe with 64k for now as fs
> that uses iomap will not have a block size > 64k.
>
> But this function needs some changes when we decide to go beyond 64k
> by returning error instead of not returning anything.
> Until then WARN_ON_ONCE would be a good stop gap for people developing
> the feature to go beyond 64k block size[1].

Sure, but please make it return an error and return that instead of
just warning and going beyond the allocated page.