nvmet: add nvmet_is_disc_subsys() helper

Add a helper function to determine if a given subsystem is a discovery
subsystem.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/admin-cmd.c

@@ -1008,7 +1008,7 @@ u16 nvmet_parse_admin_cmd(struct nvmet_req *req)
 
 	if (nvme_is_fabrics(cmd))
 		return nvmet_parse_fabrics_cmd(req);
-	if (nvmet_req_subsys(req)->type == NVME_NQN_DISC)
+	if (nvmet_is_disc_subsys(nvmet_req_subsys(req)))
 		return nvmet_parse_discovery_cmd(req);
 
 	ret = nvmet_check_ctrl_status(req);

drivers/nvme/target/core.c

@@ -1140,7 +1140,7 @@ static void nvmet_start_ctrl(struct nvmet_ctrl *ctrl)
 	 * should verify iosqes,iocqes are zeroed, however that
 	 * would break backwards compatibility, so don't enforce it.
 	 */
-	if (ctrl->subsys->type != NVME_NQN_DISC &&
+	if (!nvmet_is_disc_subsys(ctrl->subsys) &&
 	    (nvmet_cc_iosqes(ctrl->cc) != NVME_NVM_IOSQES ||
 	     nvmet_cc_iocqes(ctrl->cc) != NVME_NVM_IOCQES)) {
 		ctrl->csts = NVME_CSTS_CFS;
@@ -1281,7 +1281,7 @@ bool nvmet_host_allowed(struct nvmet_subsys *subsys, const char *hostnqn)
 	if (subsys->allow_any_host)
 		return true;
 
-	if (subsys->type == NVME_NQN_DISC) /* allow all access to disc subsys */
+	if (nvmet_is_disc_subsys(subsys)) /* allow all access to disc subsys */
 		return true;
 
 	list_for_each_entry(p, &subsys->hosts, entry) {
@@ -1413,7 +1413,7 @@ u16 nvmet_alloc_ctrl(const char *subsysnqn, const char *hostnqn,
 	 * Discovery controllers may use some arbitrary high value
 	 * in order to cleanup stale discovery sessions
 	 */
-	if ((ctrl->subsys->type == NVME_NQN_DISC) && !kato)
+	if (nvmet_is_disc_subsys(ctrl->subsys) && !kato)
 		kato = NVMET_DISC_KATO_MS;
 
 	/* keep-alive timeout in seconds */

drivers/nvme/target/nvmet.h

@@ -577,6 +577,11 @@ static inline struct nvmet_subsys *nvmet_req_subsys(struct nvmet_req *req)
 	return req->sq->ctrl->subsys;
 }
 
+static inline bool nvmet_is_disc_subsys(struct nvmet_subsys *subsys)
+{
+    return subsys->type == NVME_NQN_DISC;
+}
+
 #ifdef CONFIG_NVME_TARGET_PASSTHRU
 void nvmet_passthru_subsys_free(struct nvmet_subsys *subsys);
 int nvmet_passthru_ctrl_enable(struct nvmet_subsys *subsys);