[PATCHv5 1/8] blk-mq-dma: introduce blk_map_iter

[Christoph Hellwig]

> +struct blk_map_iter {
> +	phys_addr_t			paddr;
> +	u32				len;
> +	struct bvec_iter		iter;
> +	struct bio			*bio;
> +};

This now mixes the output previous in the phys_vec, and instead
of keeping it private to the implementation exposes it to all the
callers.  I could not find an explanation in the commit log, nor
something that makes use of it later in the series.

If possible I'd like to keep these separate and the output isolated
in blk-mq-dma.c.  But if there's a good reason to merge them, please
add it to the commit log, and also clearly document the usage of the
fields in the (public) structure.  Especially the len member could
very easily confuse.