nvme: enable retries for authentication commands

Authentication commands might trigger a lengthy computation on the
controller or even a callout to an external entity.
In these cases the controller might return a status without the DNR
bit set, indicating that the command should be retried.
This patch enables retries for authentication commands  by setting
NVME_SUBMIT_RETRY for __nvme_submit_sync_cmd().
Reported-by: Martin George <marting@netapp.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>

drivers/nvme/host/auth.c

@@ -58,7 +58,7 @@ static int nvme_auth_submit(struct nvme_ctrl *ctrl, int qid,
 			    void *data, size_t data_len, bool auth_send)
 {
 	struct nvme_command cmd = {};
-	nvme_submit_flags_t flags = 0;
+	nvme_submit_flags_t flags = NVME_SUBMIT_RETRY;
 	struct request_queue *q = ctrl->fabrics_q;
 	int ret;
 

drivers/nvme/host/core.c

@@ -1070,6 +1070,8 @@ int __nvme_submit_sync_cmd(struct request_queue *q, struct nvme_command *cmd,
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 	nvme_init_request(req, cmd);
+	if (flags & NVME_SUBMIT_RETRY)
+		req->cmd_flags &= ~REQ_FAILFAST_DRIVER;
 
 	if (buffer && bufflen) {
 		ret = blk_rq_map_kern(q, req, buffer, bufflen, GFP_KERNEL);

drivers/nvme/host/nvme.h

@@ -849,6 +849,8 @@ enum {
 	NVME_SUBMIT_NOWAIT = (__force nvme_submit_flags_t)(1 << 1),
 	/* Set BLK_MQ_REQ_RESERVED when allocating request */
 	NVME_SUBMIT_RESERVED = (__force nvme_submit_flags_t)(1 << 2),
+	/* Retry command when NVME_SC_DNR is not set in the result */
+	NVME_SUBMIT_RETRY = (__force nvme_submit_flags_t)(1 << 3),
 };
 
 int nvme_submit_sync_cmd(struct request_queue *q, struct nvme_command *cmd,