Re: [PATCH v7 02/13] iov_iter: add iterator type for dmabuf maps

[Pavel Begunkov]

On 10/5/26 10:10, Christoph Hellwig wrote:
> On Mon, Sep 28, 2026 at 02:32:18PM +0100, Pavel Begunkov wrote:
> > Introduce a new iterator type for dmabuf maps. The map in an opaque
> > object with internals and format specific to the subsystem / driver, and
> > only it can use that subsystem / driver for issuing IO. The task of the
> > middle layers is to pass the map / iterator further down, maybe doing
> > basic splitting and length checking. The iterator can only be used by
> > operations of the file the associated map was created for.
> >
> > Suggested-by: Keith Busch <kbusch@xxxxxxxxxx>
> > Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> > Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
>
> FYI, I think the Sashiko complaint about iterate_and_advance2
> is correct here.  We don't really hit that in the series, but leaving
> iov_iter methods partially implemented and fall through to others
> seems dangerous.  At minimum that needs a WARN_ON to catch that case.

v7 already covers iterate_and_advance2(). It complains about
iterate_and_advance_kernel() but there are many types this one
doesn't support.

--
Pavel Begunkov