nvmet: clean up command parsing a bit

Move the special cases for fabrics commands and the discovery controller
to nvmet_parse_admin_cmd in preparation for adding passthrough support.
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/target/admin-cmd.c

@@ -879,6 +879,11 @@ u16 nvmet_parse_admin_cmd(struct nvmet_req *req)
 	struct nvme_command *cmd = req->cmd;
 	u16 ret;
 
+	if (nvme_is_fabrics(cmd))
+		return nvmet_parse_fabrics_cmd(req);
+	if (req->sq->ctrl->subsys->type == NVME_NQN_DISC)
+		return nvmet_parse_discovery_cmd(req);
+
 	ret = nvmet_check_ctrl_status(req, cmd);
 	if (unlikely(ret))
 		return ret;

drivers/nvme/target/core.c

@@ -892,14 +892,10 @@ bool nvmet_req_init(struct nvmet_req *req, struct nvmet_cq *cq,
 	}
 
 	if (unlikely(!req->sq->ctrl))
-		/* will return an error for any Non-connect command: */
+		/* will return an error for any non-connect command: */
 		status = nvmet_parse_connect_cmd(req);
 	else if (likely(req->sq->qid != 0))
 		status = nvmet_parse_io_cmd(req);
-	else if (nvme_is_fabrics(req->cmd))
-		status = nvmet_parse_fabrics_cmd(req);
-	else if (req->sq->ctrl->subsys->type == NVME_NQN_DISC)
-		status = nvmet_parse_discovery_cmd(req);
 	else
 		status = nvmet_parse_admin_cmd(req);