nvme-pci: do not build a scatterlist to map metadata

We always have exactly one segment, so we can simply call dma_map_bvec.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 030ee94..0679ac7 100644 (file)
--- 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;