[PATCH 09/17] nvmet: prepare metadata request

[Max Gurtovoy <maxg@xxxxxxxxxxxx>]

From: Israel Rukshin <israelr@xxxxxxxxxxxx>

Allocate the metadata SGL buffers and set metadata fields for the
request. This is a preparation for adding metadata support over the
fabrics.

Signed-off-by: Israel Rukshin <israelr@xxxxxxxxxxxx>
Reviewed-by: Max Gurtovoy <maxg@xxxxxxxxxxxx>
---
 drivers/nvme/target/core.c  | 48 ++++++++++++++++++++++++++++++++++++++-------
 drivers/nvme/target/nvmet.h |  5 +++++
 2 files changed, 46 insertions(+), 7 deletions(-)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index b685f99d..3899b2b4 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -873,13 +873,17 @@ bool nvmet_req_init(struct nvmet_req *req, struct nvmet_cq *cq,
 	req->sq = sq;
 	req->ops = ops;
 	req->sg = NULL;
+	req->md_sg = NULL;
 	req->sg_cnt = 0;
+	req->md_sg_cnt = 0;
 	req->transfer_len = 0;
+	req->md_len = 0;
 	req->cqe->status = 0;
 	req->cqe->sq_head = 0;
 	req->ns = NULL;
 	req->error_loc = NVMET_NO_ERROR_LOC;
 	req->error_slba = 0;
+	req->use_md = false;
 
 	trace_nvmet_req_init(req, req->cmd);
 
@@ -962,6 +966,7 @@ bool nvmet_check_data_len_lte(struct nvmet_req *req, size_t data_len)
 int nvmet_req_alloc_sgl(struct nvmet_req *req)
 {
 	struct pci_dev *p2p_dev = NULL;
+	int data_len = req->transfer_len - req->md_len;
 
 	if (IS_ENABLED(CONFIG_PCI_P2PDMA)) {
 		if (req->sq->ctrl && req->ns)
@@ -971,11 +976,23 @@ int nvmet_req_alloc_sgl(struct nvmet_req *req)
 		req->p2p_dev = NULL;
 		if (req->sq->qid && p2p_dev) {
 			req->sg = pci_p2pmem_alloc_sgl(p2p_dev, &req->sg_cnt,
-						       req->transfer_len);
-			if (req->sg) {
-				req->p2p_dev = p2p_dev;
-				return 0;
+						       data_len);
+			if (!req->sg)
+				goto fallback;
+
+			if (req->md_len) {
+				req->md_sg =
+					pci_p2pmem_alloc_sgl(p2p_dev,
+							     &req->md_sg_cnt,
+							     req->md_len);
+				if (!req->md_sg) {
+					pci_p2pmem_free_sgl(req->p2p_dev,
+							    req->sg);
+					goto fallback;
+				}
 			}
+			req->p2p_dev = p2p_dev;
+			return 0;
 		}
 
 		/*
@@ -984,23 +1001,40 @@ int nvmet_req_alloc_sgl(struct nvmet_req *req)
 		 */
 	}
 
-	req->sg = sgl_alloc(req->transfer_len, GFP_KERNEL, &req->sg_cnt);
+fallback:
+	req->sg = sgl_alloc(data_len, GFP_KERNEL, &req->sg_cnt);
 	if (unlikely(!req->sg))
 		return -ENOMEM;
 
+	if (req->md_len) {
+		req->md_sg = sgl_alloc(req->md_len, GFP_KERNEL,
+					 &req->md_sg_cnt);
+		if (unlikely(!req->md_sg)) {
+			sgl_free(req->sg);
+			return -ENOMEM;
+		}
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(nvmet_req_alloc_sgl);
 
 void nvmet_req_free_sgl(struct nvmet_req *req)
 {
-	if (req->p2p_dev)
+	if (req->p2p_dev) {
 		pci_p2pmem_free_sgl(req->p2p_dev, req->sg);
-	else
+		if (req->md_sg)
+			pci_p2pmem_free_sgl(req->p2p_dev, req->md_sg);
+	} else {
 		sgl_free(req->sg);
+		if (req->md_sg)
+			sgl_free(req->md_sg);
+	}
 
 	req->sg = NULL;
+	req->md_sg = NULL;
 	req->sg_cnt = 0;
+	req->md_sg_cnt = 0;
 }
 EXPORT_SYMBOL_GPL(nvmet_req_free_sgl);
 
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 421dff3..8c75667 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -302,6 +302,7 @@ struct nvmet_req {
 	struct nvmet_cq		*cq;
 	struct nvmet_ns		*ns;
 	struct scatterlist	*sg;
+	struct scatterlist	*md_sg;
 	struct bio_vec		inline_bvec[NVMET_MAX_INLINE_BIOVEC];
 	union {
 		struct {
@@ -315,8 +316,10 @@ struct nvmet_req {
 		} f;
 	};
 	int			sg_cnt;
+	int			md_sg_cnt;
 	/* data length as parsed from the SGL descriptor: */
 	size_t			transfer_len;
+	size_t			md_len;
 
 	struct nvmet_port	*port;
 
@@ -327,6 +330,8 @@ struct nvmet_req {
 	struct device		*p2p_client;
 	u16			error_loc;
 	u64			error_slba;
+	/* Metadata support */
+	bool			use_md;
 };
 
 extern struct workqueue_struct *buffered_io_wq;
-- 
1.8.3.1