nvmet: allow host connect even if no allowed subsystems are exported

It is perfectly valid that a host connects to a discovery subsystem
and gets an empty discovery log page since no subsystems are
provisioned to it. No reason to disallow connecting to the discovery
subsystem all together.
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Jay Sternberg <jay.e.sternberg@intel.com>
Reviewed-by: Phil Cayton <phil.cayton@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/target/core.c

@@ -1032,14 +1032,18 @@ u16 nvmet_check_ctrl_status(struct nvmet_req *req, struct nvme_command *cmd)
 	return 0;
 }
 
-static bool __nvmet_host_allowed(struct nvmet_subsys *subsys,
-		const char *hostnqn)
+bool nvmet_host_allowed(struct nvmet_subsys *subsys, const char *hostnqn)
 {
 	struct nvmet_host_link *p;
 
+	lockdep_assert_held(&nvmet_config_sem);
+
 	if (subsys->allow_any_host)
 		return true;
 
+	if (subsys->type == NVME_NQN_DISC) /* allow all access to disc subsys */
+		return true;
+
 	list_for_each_entry(p, &subsys->hosts, entry) {
 		if (!strcmp(nvmet_host_name(p->host), hostnqn))
 			return true;
@@ -1048,30 +1052,6 @@ static bool __nvmet_host_allowed(struct nvmet_subsys *subsys,
 	return false;
 }
 
-static bool nvmet_host_discovery_allowed(struct nvmet_req *req,
-		const char *hostnqn)
-{
-	struct nvmet_subsys_link *s;
-
-	list_for_each_entry(s, &req->port->subsystems, entry) {
-		if (__nvmet_host_allowed(s->subsys, hostnqn))
-			return true;
-	}
-
-	return false;
-}
-
-bool nvmet_host_allowed(struct nvmet_req *req, struct nvmet_subsys *subsys,
-		const char *hostnqn)
-{
-	lockdep_assert_held(&nvmet_config_sem);
-
-	if (subsys->type == NVME_NQN_DISC)
-		return nvmet_host_discovery_allowed(req, hostnqn);
-	else
-		return __nvmet_host_allowed(subsys, hostnqn);
-}
-
 /*
  * Note: ctrl->subsys->lock should be held when calling this function
  */
@@ -1122,7 +1102,7 @@ u16 nvmet_alloc_ctrl(const char *subsysnqn, const char *hostnqn,
 
 	status = NVME_SC_CONNECT_INVALID_PARAM | NVME_SC_DNR;
 	down_read(&nvmet_config_sem);
-	if (!nvmet_host_allowed(req, subsys, hostnqn)) {
+	if (!nvmet_host_allowed(subsys, hostnqn)) {
 		pr_info("connect by host %s for subsystem %s not allowed\n",
 			hostnqn, subsysnqn);
 		req->rsp->result.u32 = IPO_IATTR_CONNECT_DATA(hostnqn);

drivers/nvme/target/discovery.c

@@ -107,7 +107,7 @@ static void nvmet_execute_get_disc_log_page(struct nvmet_req *req)
 
 	down_read(&nvmet_config_sem);
 	list_for_each_entry(p, &req->port->subsystems, entry) {
-		if (!nvmet_host_allowed(req, p->subsys, ctrl->hostnqn))
+		if (!nvmet_host_allowed(p->subsys, ctrl->hostnqn))
 			continue;
 		if (residual_len >= entry_size) {
 			char traddr[NVMF_TRADDR_SIZE];

drivers/nvme/target/nvmet.h

@@ -468,8 +468,7 @@ extern u32 nvmet_ana_group_enabled[NVMET_MAX_ANAGRPS + 1];
 extern u64 nvmet_ana_chgcnt;
 extern struct rw_semaphore nvmet_ana_sem;
 
-bool nvmet_host_allowed(struct nvmet_req *req, struct nvmet_subsys *subsys,
-		const char *hostnqn);
+bool nvmet_host_allowed(struct nvmet_subsys *subsys, const char *hostnqn);
 
 int nvmet_bdev_ns_enable(struct nvmet_ns *ns);
 int nvmet_file_ns_enable(struct nvmet_ns *ns);