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@kernel.org Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Pavel Begunkov asml.silence@gmail.com

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.