[PATCH] nvme-core: optimize process for error status NVME_SC_CMD_INTERRUPTED

[Chao Leng]

The protocol NVM-Express-1.4 define:
Command Interrupted: Command processing was interrupted and the
controller is unable to successfully complete the command. The host
should retry the command. If this status code is returned, then
the controller shall clear the Do Not Retry bit to ‘0’ in the Status
field of the CQE (refer to Figure 124). The controller shall not return
this status code unless the host has set the Advanced Command Retry
Enable (ACRE) field to 1h in the Host Behavior Support feature(refer to
section 5.21.1.22).

According the protocol define, NVME_SC_CMD_INTERRUPTED need retry.
The error code NVME_SC_CMD_INTERRUPTED should not translate to
BLK_STS_TARGET, because if the error code translate to BLK_STS_TARGET,
dm-multipah will return error to application. NVME_SC_CMD_INTERRUPTED
should translate to BLK_STS_IOERR by default, dm-multipath will fail
over to other path retry the io.

We need a mechanism for retry in the current path first in some
scenarios such as the target is dealing with an important emergency and
need host retry the io after a defined time, because dm-multipath can
not get Command Retry Delay (CRD) to control retry delay time.
according the protocol define, the error code NVME_SC_CMD_INTERRUPTED
is a good choice.

Signed-off-by: Chao Leng <lengchao at huawei.com>
---
 drivers/nvme/host/core.c | 3 +--
 drivers/nvme/host/nvme.h | 6 ++++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 66e6f7ca8947..b3307e317ece 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -211,7 +211,6 @@ static blk_status_t nvme_error_status(u16 status)
 	case NVME_SC_CAP_EXCEEDED:
 		return BLK_STS_NOSPC;
 	case NVME_SC_LBA_RANGE:
-	case NVME_SC_CMD_INTERRUPTED:
 	case NVME_SC_NS_NOT_READY:
 		return BLK_STS_TARGET;
 	case NVME_SC_BAD_ATTRIBUTES:
@@ -243,7 +242,7 @@ static blk_status_t nvme_error_status(u16 status)
 
 static inline bool nvme_req_needs_retry(struct request *req)
 {
-	if (blk_noretry_request(req))
+	if (!nvme_req_local_retry(req) && blk_noretry_request(req))
 		return false;
 	if (nvme_req(req)->status & NVME_SC_DNR)
 		return false;
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 1de3f9b827aa..3213aae8985c 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -725,4 +725,10 @@ void nvme_hwmon_init(struct nvme_ctrl *ctrl);
 static inline void nvme_hwmon_init(struct nvme_ctrl *ctrl) { }
 #endif
 
+static inline bool nvme_req_local_retry(struct request *req)
+{
+	if (nvme_req(req)->status == NVME_SC_CMD_INTERRUPTED)
+		return true;
+	return false;
+}
 #endif /* _NVME_H */
-- 
2.16.4