[PATCH 2/7] sg_ring: use in virtio.

Using sg_rings, we can join together scatterlists returned by other subsystems, without needing to allocate an extra element for chaining. This helps the virtio_blk device which wants to prepend and append metadata to the request's scatterlist. As an added bonus, the old virtio layer used to pass

[PATCH 2/7] sg_ring: use in virtio.

Using sg_rings, we can join together scatterlists returned by other subsystems, without needing to allocate an extra element for chaining. This helps the virtio_blk device which wants to prepend and append metadata to the request's scatterlist. As an added bonus, the old virtio layer used to pass