nvmet: avoid duplicate qid in connect cmd

According to the NVMe specification, if the host sends a Connect command
specifying a queue id which has already been created, a status value of
NVME_SC_CMD_SEQ_ERROR is returned.
Signed-off-by: Amit Engel <amit.engel@dell.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/core.c

@@ -802,6 +802,7 @@ void nvmet_sq_destroy(struct nvmet_sq *sq)
 		 * controller teardown as a result of a keep-alive expiration.
 		 */
 		ctrl->reset_tbkas = true;
+		sq->ctrl->sqs[sq->qid] = NULL;
 		nvmet_ctrl_put(ctrl);
 		sq->ctrl = NULL; /* allows reusing the queue later */
 	}

drivers/nvme/target/fabrics-cmd.c

@@ -111,12 +111,6 @@ static u16 nvmet_install_queue(struct nvmet_ctrl *ctrl, struct nvmet_req *req)
 	struct nvmet_ctrl *old;
 	u16 ret;
 
-	old = cmpxchg(&req->sq->ctrl, NULL, ctrl);
-	if (old) {
-		pr_warn("queue already connected!\n");
-		req->error_loc = offsetof(struct nvmf_connect_command, opcode);
-		return NVME_SC_CONNECT_CTRL_BUSY | NVME_SC_DNR;
-	}
 	if (!sqsize) {
 		pr_warn("queue size zero!\n");
 		req->error_loc = offsetof(struct nvmf_connect_command, sqsize);
@@ -125,6 +119,19 @@ static u16 nvmet_install_queue(struct nvmet_ctrl *ctrl, struct nvmet_req *req)
 		goto err;
 	}
 
+	if (ctrl->sqs[qid] != NULL) {
+		pr_warn("qid %u has already been created\n", qid);
+		req->error_loc = offsetof(struct nvmf_connect_command, qid);
+		return NVME_SC_CMD_SEQ_ERROR | NVME_SC_DNR;
+	}
+
+	old = cmpxchg(&req->sq->ctrl, NULL, ctrl);
+	if (old) {
+		pr_warn("queue already connected!\n");
+		req->error_loc = offsetof(struct nvmf_connect_command, opcode);
+		return NVME_SC_CONNECT_CTRL_BUSY | NVME_SC_DNR;
+	}
+
 	/* note: convert queue size from 0's-based value to 1's-based value */
 	nvmet_cq_setup(ctrl, req->cq, qid, sqsize + 1);
 	nvmet_sq_setup(ctrl, req->sq, qid, sqsize + 1);
@@ -139,6 +146,7 @@ static u16 nvmet_install_queue(struct nvmet_ctrl *ctrl, struct nvmet_req *req)
 		if (ret) {
 			pr_err("failed to install queue %d cntlid %d ret %x\n",
 				qid, ctrl->cntlid, ret);
+			ctrl->sqs[qid] = NULL;
 			goto err;
 		}
 	}