[RFC v2 18/21] nvme-pci: remove optimizations for single DMA entry

[Leon Romanovsky]

From: Leon Romanovsky <leonro at nvidia.com>

Future patches will remove SG table allocation from the NVMe PCI
code, which these single DMA entries tried to optimize. As a
preparation, let's remove them to unify the DMA mapping code.

Signed-off-by: Leon Romanovsky <leonro at nvidia.com>
---
 drivers/nvme/host/pci.c | 69 -----------------------------------------
 1 file changed, 69 deletions(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 6cd9395ba9ec..a9a66f184138 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -233,7 +233,6 @@ struct nvme_iod {
 	bool aborted;
 	s8 nr_allocations;	/* PRP list pool allocations. 0 means small
 				   pool in use */
-	unsigned int dma_len;	/* length of single DMA segment mapping */
 	dma_addr_t first_dma;
 	dma_addr_t meta_dma;
 	struct sg_table sgt;
@@ -541,12 +540,6 @@ static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
 {
 	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
 
-	if (iod->dma_len) {
-		dma_unmap_page(dev->dev, iod->first_dma, iod->dma_len,
-			       rq_dma_dir(req));
-		return;
-	}
-
 	WARN_ON_ONCE(!iod->sgt.nents);
 
 	dma_unmap_sgtable(dev->dev, &iod->sgt, rq_dma_dir(req), 0);
@@ -696,11 +689,6 @@ static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev,
 	/* setting the transfer type as SGL */
 	cmd->flags = NVME_CMD_SGL_METABUF;
 
-	if (entries == 1) {
-		nvme_pci_sgl_set_data(&cmd->dptr.sgl, sg);
-		return BLK_STS_OK;
-	}
-
 	if (entries <= (256 / sizeof(struct nvme_sgl_desc))) {
 		pool = dev->prp_small_pool;
 		iod->nr_allocations = 0;
@@ -727,45 +715,6 @@ static blk_status_t nvme_pci_setup_sgls(struct nvme_dev *dev,
 	return BLK_STS_OK;
 }
 
-static blk_status_t nvme_setup_prp_simple(struct nvme_dev *dev,
-		struct request *req, struct nvme_rw_command *cmnd,
-		struct bio_vec *bv)
-{
-	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
-	unsigned int offset = bv->bv_offset & (NVME_CTRL_PAGE_SIZE - 1);
-	unsigned int first_prp_len = NVME_CTRL_PAGE_SIZE - offset;
-
-	iod->first_dma = dma_map_bvec(dev->dev, bv, rq_dma_dir(req), 0);
-	if (dma_mapping_error(dev->dev, iod->first_dma))
-		return BLK_STS_RESOURCE;
-	iod->dma_len = bv->bv_len;
-
-	cmnd->dptr.prp1 = cpu_to_le64(iod->first_dma);
-	if (bv->bv_len > first_prp_len)
-		cmnd->dptr.prp2 = cpu_to_le64(iod->first_dma + first_prp_len);
-	else
-		cmnd->dptr.prp2 = 0;
-	return BLK_STS_OK;
-}
-
-static blk_status_t nvme_setup_sgl_simple(struct nvme_dev *dev,
-		struct request *req, struct nvme_rw_command *cmnd,
-		struct bio_vec *bv)
-{
-	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
-
-	iod->first_dma = dma_map_bvec(dev->dev, bv, rq_dma_dir(req), 0);
-	if (dma_mapping_error(dev->dev, iod->first_dma))
-		return BLK_STS_RESOURCE;
-	iod->dma_len = bv->bv_len;
-
-	cmnd->flags = NVME_CMD_SGL_METABUF;
-	cmnd->dptr.sgl.addr = cpu_to_le64(iod->first_dma);
-	cmnd->dptr.sgl.length = cpu_to_le32(iod->dma_len);
-	cmnd->dptr.sgl.type = NVME_SGL_FMT_DATA_DESC << 4;
-	return BLK_STS_OK;
-}
-
 static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
 		struct nvme_command *cmnd)
 {
@@ -773,24 +722,6 @@ static blk_status_t nvme_map_data(struct nvme_dev *dev, struct request *req,
 	blk_status_t ret = BLK_STS_RESOURCE;
 	int rc;
 
-	if (blk_rq_nr_phys_segments(req) == 1) {
-		struct nvme_queue *nvmeq = req->mq_hctx->driver_data;
-		struct bio_vec bv = req_bvec(req);
-
-		if (!is_pci_p2pdma_page(bv.bv_page)) {
-			if ((bv.bv_offset & (NVME_CTRL_PAGE_SIZE - 1)) +
-			     bv.bv_len <= NVME_CTRL_PAGE_SIZE * 2)
-				return nvme_setup_prp_simple(dev, req,
-							     &cmnd->rw, &bv);
-
-			if (nvmeq->qid && sgl_threshold &&
-			    nvme_ctrl_sgl_supported(&dev->ctrl))
-				return nvme_setup_sgl_simple(dev, req,
-							     &cmnd->rw, &bv);
-		}
-	}
-
-	iod->dma_len = 0;
 	iod->sgt.sgl = mempool_alloc(dev->iod_mempool, GFP_ATOMIC);
 	if (!iod->sgt.sgl)
 		return BLK_STS_RESOURCE;
-- 
2.46.0