[PATCHv2 7/7] nvme: convert metadata mapping to dma iter

[Christoph Hellwig]

On Mon, Jul 21, 2025 at 07:15:41AM -0600, Keith Busch wrote:
> > This should probably just set up the linear metadata pointer instead
> > of a single-segment SGL.
> 
> Okay, but we should still use SGL with user passthrough commands for
> memory safety. Even if we have an iommu protecting access, there's still
> a possibility of corrupting adjacent iova's if using MPTR.

True.

> In this patch, the nr_meta_descriptors value matches the sg_list length.
> The only real reason I need this 'nr_' value is to distinguish the
> single data descriptor condition from the segment descriptor use, but I
> can just add an iod flag for that too and save some space.

Yes, that would be great.