[Intel-gfx] add remap_pfn_range_notrack instead of reinventing it in i915

[Christoph Hellwig]

On Mon, Mar 01, 2021 at 09:44:13AM +0100, Daniel Vetter wrote:
> On Mon, Mar 01, 2021 at 09:33:18AM +0100, Christoph Hellwig wrote:
> > Hi all,
> > 
> > i915 has some reason to want to avoid the track_pfn_remap overhead in
> > remap_pfn_range.  Add a function to the core VM to do just that rather
> > than reinventing the functionality poorly in the driver.
> 
> It's not _notrack it's "rely on the tracking established by the struct
> io_mapping". Exporting a _notrack version to drivers sounds like not
> something we want to ever do. So I think you want a helper which takes the
> io_mapping, and not something that encourages drivers to go full stupid.

As far as I can tell there is no struct io_mapping anywhere near
remap_io_sg.