[RFC RESEND 16/16] nvme-pci: use blk_rq_dma_map() for NVMe SGL

[Keith Busch]

On Tue, Mar 05, 2024 at 01:18:47PM +0200, Leon Romanovsky wrote:
> @@ -236,7 +236,9 @@ struct nvme_iod {
>  	unsigned int dma_len;	/* length of single DMA segment mapping */
>  	dma_addr_t first_dma;
>  	dma_addr_t meta_dma;
> -	struct sg_table sgt;
> +	struct dma_iova_attrs iova;
> +	dma_addr_t dma_link_address[128];
> +	u16 nr_dma_link_address;
>  	union nvme_descriptor list[NVME_MAX_NR_ALLOCATIONS];
>  };

That's quite a lot of space to add to the iod. We preallocate one for
every request, and there could be millions of them.