From mboxrd@z Thu Jan  1 00:00:00 1970
From: Chaitanya.Kulkarni@wdc.com (Chaitanya Kulkarni)
Date: Mon, 25 Mar 2019 05:27:17 +0000
Subject: [PATCH 10/15] nvme-pci: do not build a scatterlist to map metadata
References: <20190321231037.25104-1-hch@lst.de>
 <20190321231037.25104-11-hch@lst.de>
Message-ID: <SN6PR04MB4527703215979281EE3C18A9865E0@SN6PR04MB4527.namprd04.prod.outlook.com>

On 3/21/19 4:12 PM, Christoph Hellwig wrote:
> We always have exactly one segment, so we can simply call dma_map_bvec.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
>   drivers/nvme/host/pci.c | 23 ++++++++++-------------
>   1 file changed, 10 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index bc4ee869fe82..a7dad24e0406 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -221,7 +221,7 @@ struct nvme_iod {
>   	int npages;		/* In the PRP list. 0 means small pool in use */
>   	int nents;		/* Used in scatterlist */
>   	dma_addr_t first_dma;
> -	struct scatterlist meta_sg; /* metadata requires single contiguous buffer */
> +	dma_addr_t meta_dma;
>   	struct scatterlist *sg;
>   	struct scatterlist inline_sg[0];
>   };
> @@ -592,13 +592,16 @@ static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
>   	dma_addr_t dma_addr = iod->first_dma, next_dma_addr;
>   	int i;
>   
> +	if (blk_integrity_rq(req)) {
> +		dma_unmap_page(dev->dev, iod->meta_dma,
> +				rq_integrity_vec(req)->bv_len, dma_dir);
> +	}
> +
>   	if (iod->nents) {
>   		/* P2PDMA requests do not need to be unmapped */
>   		if (!is_pci_p2pdma_page(sg_page(iod->sg)))
>   			dma_unmap_sg(dev->dev, iod->sg, iod->nents, dma_dir);
>   
> -		if (blk_integrity_rq(req))
> -			dma_unmap_sg(dev->dev, &iod->meta_sg, 1, dma_dir);
>   	}
>   
>   	if (iod->npages == 0)
> @@ -861,17 +864,11 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
>   
>   	ret = BLK_STS_IOERR;
>   	if (blk_integrity_rq(req)) {
> -		if (blk_rq_count_integrity_sg(q, req->bio) != 1)
> -			goto out;
> -
> -		sg_init_table(&iod->meta_sg, 1);
> -		if (blk_rq_map_integrity_sg(q, req->bio, &iod->meta_sg) != 1)
> -			goto out;
> -
> -		if (!dma_map_sg(dev->dev, &iod->meta_sg, 1, dma_dir))
> +		iod->meta_dma = dma_map_bvec(dev->dev, rq_integrity_vec(req),
> +				dma_dir, 0);
> +		if (dma_mapping_error(dev->dev, iod->meta_dma))
>   			goto out;
> -
> -		cmnd->rw.metadata = cpu_to_le64(sg_dma_address(&iod->meta_sg));
> +		cmnd->rw.metadata = cpu_to_le64(iod->meta_dma);
>   	}
>   
>   	return BLK_STS_OK;
>

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>