[RFC PATCH v3 2/3] nvme: keep nvme_command instead of pointer to it

[Kanchan Joshi <joshi.k@xxxxxxxxxxx>]

nvme_req structure originally contained a pointer to nvme_command.
Change nvme_req structure to keep the command itself.
This helps in avoiding hot-path memory-allocation for async-passthrough.

Signed-off-by: Anuj Gupta <anuj20.g@xxxxxxxxxxx>
Signed-off-by: Kanchan Joshi <joshi.k@xxxxxxxxxxx>
---
 drivers/nvme/host/core.c     |  6 +++---
 drivers/nvme/host/fabrics.c  |  4 ++--
 drivers/nvme/host/lightnvm.c | 16 +++++-----------
 drivers/nvme/host/nvme.h     |  2 +-
 4 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index e68a8c4ac5a6..46c1bb7a89f0 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -596,7 +596,7 @@ static inline void nvme_init_request(struct request *req,
 
 	req->cmd_flags |= REQ_FAILFAST_DRIVER;
 	nvme_clear_nvme_request(req);
-	nvme_req(req)->cmd = cmd;
+	nvme_req(req)->cmd = *cmd;
 }
 
 struct request *nvme_alloc_request(struct request_queue *q,
@@ -728,7 +728,7 @@ static void nvme_assign_write_stream(struct nvme_ctrl *ctrl,
 static void nvme_setup_passthrough(struct request *req,
 		struct nvme_command *cmd)
 {
-	memcpy(cmd, nvme_req(req)->cmd, sizeof(*cmd));
+	memcpy(cmd, &nvme_req(req)->cmd, sizeof(*cmd));
 	/* passthru commands should let the driver set the SGL flags */
 	cmd->common.flags &= ~NVME_CMD_SGL_ALL;
 }
@@ -1128,7 +1128,7 @@ static void nvme_passthru_end(struct nvme_ctrl *ctrl, u32 effects)
 
 void nvme_execute_passthru_rq(struct request *rq)
 {
-	struct nvme_command *cmd = nvme_req(rq)->cmd;
+	struct nvme_command *cmd = &nvme_req(rq)->cmd;
 	struct nvme_ctrl *ctrl = nvme_req(rq)->ctrl;
 	struct nvme_ns *ns = rq->q->queuedata;
 	struct gendisk *disk = ns ? ns->disk : NULL;
diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c
index 5dfd806fc2d2..c374dcf6595e 100644
--- a/drivers/nvme/host/fabrics.c
+++ b/drivers/nvme/host/fabrics.c
@@ -578,8 +578,8 @@ bool __nvmf_check_ready(struct nvme_ctrl *ctrl, struct request *rq,
 	 */
 	switch (ctrl->state) {
 	case NVME_CTRL_CONNECTING:
-		if (blk_rq_is_passthrough(rq) && nvme_is_fabrics(req->cmd) &&
-		    req->cmd->fabrics.fctype == nvme_fabrics_type_connect)
+		if (blk_rq_is_passthrough(rq) && nvme_is_fabrics(&req->cmd) &&
+		    req->cmd.fabrics.fctype == nvme_fabrics_type_connect)
 			return true;
 		break;
 	default:
diff --git a/drivers/nvme/host/lightnvm.c b/drivers/nvme/host/lightnvm.c
index b705988629f2..5f4d7f0f5d8d 100644
--- a/drivers/nvme/host/lightnvm.c
+++ b/drivers/nvme/host/lightnvm.c
@@ -640,7 +640,6 @@ static void nvme_nvm_end_io(struct request *rq, blk_status_t status)
 	rqd->error = nvme_req(rq)->status;
 	nvm_end_io(rqd);
 
-	kfree(nvme_req(rq)->cmd);
 	blk_mq_free_request(rq);
 }
 
@@ -672,25 +671,21 @@ static int nvme_nvm_submit_io(struct nvm_dev *dev, struct nvm_rq *rqd,
 {
 	struct nvm_geo *geo = &dev->geo;
 	struct request_queue *q = dev->q;
-	struct nvme_nvm_command *cmd;
+	struct nvme_nvm_command cmd;
 	struct request *rq;
 	int ret;
 
-	cmd = kzalloc(sizeof(struct nvme_nvm_command), GFP_KERNEL);
-	if (!cmd)
-		return -ENOMEM;
-
-	rq = nvme_nvm_alloc_request(q, rqd, cmd);
+	rq = nvme_nvm_alloc_request(q, rqd, &cmd);
 	if (IS_ERR(rq)) {
 		ret = PTR_ERR(rq);
-		goto err_free_cmd;
+		goto err_cmd;
 	}
 
 	if (buf) {
 		ret = blk_rq_map_kern(q, rq, buf, geo->csecs * rqd->nr_ppas,
 				GFP_KERNEL);
 		if (ret)
-			goto err_free_cmd;
+			goto err_cmd;
 	}
 
 	rq->end_io_data = rqd;
@@ -699,8 +694,7 @@ static int nvme_nvm_submit_io(struct nvm_dev *dev, struct nvm_rq *rqd,
 
 	return 0;
 
-err_free_cmd:
-	kfree(cmd);
+err_cmd:
 	return ret;
 }
 
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 07b34175c6ce..0254aa611dfa 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -157,7 +157,7 @@ enum nvme_quirks {
  * this structure as the first member of their request-private data.
  */
 struct nvme_request {
-	struct nvme_command	*cmd;
+	struct nvme_command	cmd;
 	union nvme_result	result;
 	u8			retries;
 	u8			flags;
-- 
2.25.1