[PATCH 2/2 v2] UBI: Block: Add blk-mq support

[Christoph Hellwig]

> +	struct ubi_sgl usgl;

Btw, what's in struct ubi_sgl?  Can't find that in my tree.

> +static void ubiblock_do_work(struct work_struct *work)
> +{
> +	int ret;
> +	struct ubiblock_pdu *pdu = container_of(work, struct ubiblock_pdu, work);
> +	struct request *req = blk_mq_rq_from_pdu(pdu);
> +
> +	blk_mq_start_request(req);
> +	blk_rq_map_sg(req->q, req, pdu->usgl.sg);

blk_rq_map_sg returns the number of entries actually mapped, which
might be smaller than the number passed in due to merging.