nvme-pci: refactor nvme_unmap_data

Split out three helpers from nvme_unmap_data that will allow finer grained
unwinding from nvme_map_data.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Marc Orr <marcorr@google.com>

drivers/nvme/host/pci.c

@@ -543,50 +543,71 @@ static inline bool nvme_pci_use_sgls(struct nvme_dev *dev, struct request *req)
 	return true;
 }
 
-static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
+static void nvme_free_prps(struct nvme_dev *dev, struct request *req)
 {
-	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
 	const int last_prp = NVME_CTRL_PAGE_SIZE / sizeof(__le64) - 1;
-	dma_addr_t dma_addr = iod->first_dma, next_dma_addr;
+	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+	dma_addr_t dma_addr = iod->first_dma;
 	int i;
 
-	if (iod->dma_len) {
-		dma_unmap_page(dev->dev, dma_addr, iod->dma_len,
-			       rq_dma_dir(req));
-		return;
+	for (i = 0; i < iod->npages; i++) {
+		__le64 *prp_list = nvme_pci_iod_list(req)[i];
+		dma_addr_t next_dma_addr = le64_to_cpu(prp_list[last_prp]);
+
+		dma_pool_free(dev->prp_page_pool, prp_list, dma_addr);
+		dma_addr = next_dma_addr;
 	}
 
-	WARN_ON_ONCE(!iod->nents);
+}
+
+static void nvme_free_sgls(struct nvme_dev *dev, struct request *req)
+{
+	const int last_sg = SGES_PER_PAGE - 1;
+	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+	dma_addr_t dma_addr = iod->first_dma;
+	int i;
+
+	for (i = 0; i < iod->npages; i++) {
+		struct nvme_sgl_desc *sg_list = nvme_pci_iod_list(req)[i];
+		dma_addr_t next_dma_addr = le64_to_cpu((sg_list[last_sg]).addr);
+
+		dma_pool_free(dev->prp_page_pool, sg_list, dma_addr);
+		dma_addr = next_dma_addr;
+	}
+
+}
+
+static void nvme_unmap_sg(struct nvme_dev *dev, struct request *req)
+{
+	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
 
 	if (is_pci_p2pdma_page(sg_page(iod->sg)))
 		pci_p2pdma_unmap_sg(dev->dev, iod->sg, iod->nents,
 				    rq_dma_dir(req));
 	else
 		dma_unmap_sg(dev->dev, iod->sg, iod->nents, rq_dma_dir(req));
+}
 
+static void nvme_unmap_data(struct nvme_dev *dev, struct request *req)
+{
+	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
 
-	if (iod->npages == 0)
-		dma_pool_free(dev->prp_small_pool, nvme_pci_iod_list(req)[0],
-			dma_addr);
-
-	for (i = 0; i < iod->npages; i++) {
-		void *addr = nvme_pci_iod_list(req)[i];
-
-		if (iod->use_sgl) {
-			struct nvme_sgl_desc *sg_list = addr;
-
-			next_dma_addr =
-			    le64_to_cpu((sg_list[SGES_PER_PAGE - 1]).addr);
-		} else {
-			__le64 *prp_list = addr;
-
-			next_dma_addr = le64_to_cpu(prp_list[last_prp]);
+	if (iod->dma_len) {
+		dma_unmap_page(dev->dev, iod->first_dma, iod->dma_len,
+			       rq_dma_dir(req));
+		return;
 	}
 
-		dma_pool_free(dev->prp_page_pool, addr, dma_addr);
-		dma_addr = next_dma_addr;
-	}
+	WARN_ON_ONCE(!iod->nents);
 
+	nvme_unmap_sg(dev, req);
+	if (iod->npages == 0)
+		dma_pool_free(dev->prp_small_pool, nvme_pci_iod_list(req)[0],
+			      iod->first_dma);
+	else if (iod->use_sgl)
+		nvme_free_sgls(dev, req);
+	else
+		nvme_free_prps(dev, req);
 	mempool_free(iod->sg, dev->iod_mempool);
 }