[PATCHv4 4/4] nvme: use return value from blk_execute_rq()

[Keith Busch]

We don't have an nvme status to report if the driver's .queue_rq()
returns an error without dispatching the requested nvme command. Check
the return value from blk_execute_rq() for all passthrough commands so
the caller may know their command was not successful.

If the command is from the target passthrough interface and fails to
dispatch, synthesize the response back to the host as a internal target
error.

Signed-off-by: Keith Busch <kbusch at kernel.org>
---
v2->v3:

  Combined request dispatch with the status decoding into single
  function

 drivers/nvme/host/core.c       | 35 ++++++++++++++++++++++++++--------
 drivers/nvme/host/ioctl.c      |  6 +-----
 drivers/nvme/host/nvme.h       |  2 +-
 drivers/nvme/target/passthru.c |  8 ++++----
 4 files changed, 33 insertions(+), 18 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 2b9deaffa4e1..f4a690808010 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -609,6 +609,7 @@ EXPORT_SYMBOL_NS_GPL(nvme_put_ns, NVME_TARGET_PASSTHRU);
 
 static inline void nvme_clear_nvme_request(struct request *req)
 {
+	nvme_req(req)->status = 0;
 	nvme_req(req)->retries = 0;
 	nvme_req(req)->flags = 0;
 	req->rq_flags |= RQF_DONTPREP;
@@ -1034,6 +1035,25 @@ blk_status_t nvme_setup_cmd(struct nvme_ns *ns, struct request *req)
 }
 EXPORT_SYMBOL_GPL(nvme_setup_cmd);
 
+/*
+ * Return values:
+ * 0:  success
+ * >0: nvme controller's cqe status response
+ * <0: kernel error in lieu of controller response
+ */
+static int nvme_execute_rq(struct gendisk *disk, struct request *rq,
+		bool at_head)
+{
+	blk_status_t status;
+
+	status = blk_execute_rq(disk, rq, at_head);
+	if (nvme_req(rq)->flags & NVME_REQ_CANCELLED)
+		return -EINTR;
+	if (nvme_req(rq)->status)
+		return nvme_req(rq)->status;
+	return blk_status_to_errno(status);
+}
+
 /*
  * Returns 0 on success.  If the result is negative, it's a Linux error code;
  * if the result is positive, it's an NVM Express status code
@@ -1062,13 +1082,9 @@ int __nvme_submit_sync_cmd(struct request_queue *q, struct nvme_command *cmd,
 			goto out;
 	}
 
-	blk_execute_rq(NULL, req, at_head);
-	if (result)
+	ret = nvme_execute_rq(NULL, req, at_head);
+	if (result && ret >= 0)
 		*result = nvme_req(req)->result;
-	if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
-		ret = -EINTR;
-	else
-		ret = nvme_req(req)->status;
  out:
 	blk_mq_free_request(req);
 	return ret;
@@ -1156,18 +1172,21 @@ static void nvme_passthru_end(struct nvme_ctrl *ctrl, u32 effects)
 	}
 }
 
-void nvme_execute_passthru_rq(struct request *rq)
+int nvme_execute_passthru_rq(struct request *rq)
 {
 	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;
 	u32 effects;
+	int  ret;
 
 	effects = nvme_passthru_start(ctrl, ns, cmd->common.opcode);
-	blk_execute_rq(disk, rq, 0);
+	ret = nvme_execute_rq(disk, rq, false);
 	if (effects) /* nothing to be done for zero cmd effects */
 		nvme_passthru_end(ctrl, effects);
+
+	return ret;
 }
 EXPORT_SYMBOL_NS_GPL(nvme_execute_passthru_rq, NVME_TARGET_PASSTHRU);
 
diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 2e7780ea0354..85cfad3dd692 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -93,11 +93,7 @@ static int nvme_submit_user_cmd(struct request_queue *q,
 		}
 	}
 
-	nvme_execute_passthru_rq(req);
-	if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
-		ret = -EINTR;
-	else
-		ret = nvme_req(req)->status;
+	ret = nvme_execute_passthru_rq(req);
 	if (result)
 		*result = le64_to_cpu(nvme_req(req)->result.u64);
 	if (meta && !ret && !write) {
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 499681bc0286..7557f3404615 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -871,7 +871,7 @@ static inline void nvme_hwmon_exit(struct nvme_ctrl *ctrl)
 
 u32 nvme_command_effects(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 			 u8 opcode);
-void nvme_execute_passthru_rq(struct request *rq);
+int nvme_execute_passthru_rq(struct request *rq);
 struct nvme_ctrl *nvme_ctrl_from_file(struct file *file);
 struct nvme_ns *nvme_find_get_ns(struct nvme_ctrl *ctrl, unsigned nsid);
 void nvme_put_ns(struct nvme_ns *ns);
diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
index 39b1473f7204..ba28ce42cb55 100644
--- a/drivers/nvme/target/passthru.c
+++ b/drivers/nvme/target/passthru.c
@@ -153,11 +153,10 @@ static void nvmet_passthru_execute_cmd_work(struct work_struct *w)
 {
 	struct nvmet_req *req = container_of(w, struct nvmet_req, p.work);
 	struct request *rq = req->p.rq;
-	u16 status;
+	int status;
 
-	nvme_execute_passthru_rq(rq);
+	status = nvme_execute_passthru_rq(rq);
 
-	status = nvme_req(rq)->status;
 	if (status == NVME_SC_SUCCESS &&
 	    req->cmd->common.opcode == nvme_admin_identify) {
 		switch (req->cmd->identify.cns) {
@@ -168,7 +167,8 @@ static void nvmet_passthru_execute_cmd_work(struct work_struct *w)
 			nvmet_passthru_override_id_ns(req);
 			break;
 		}
-	}
+	} else if (status < 0)
+		status = NVME_SC_INTERNAL;
 
 	req->cqe->result = nvme_req(rq)->result;
 	nvmet_req_complete(req, status);
-- 
2.25.4