tree: rework nvme_scan_subsystem()

The nvme subsystem does not have a 'hostnqn' sysfs entry, so we
cannot infer from the nvme subsystem sysfs entry to which host
it relates. And really, the subsystem should already have been
created by the previous call to nvme_scan_ctrl().
So do not call nvme_lookup_subsystem() in nvme_scan_subystem(),
but rather just validate the sysfs subsystem entries and create
any missing subsystems.

Signed-off-by: Hannes Reinecke <[email protected]>

Author: hreinecke

src/nvme/tree.c

@@ -516,9 +516,8 @@ static int nvme_init_subsystem(nvme_subsystem_t s, const char *name)
 static int nvme_scan_subsystem(struct nvme_root *r, const char *name,
 			       nvme_scan_filter_t f)
 {
-	struct nvme_subsystem *s;
+	struct nvme_subsystem *s = NULL, *_s;
 	char *path, *subsysnqn;
-	char *hostnqn, *hostid = NULL;
 	nvme_host_t h = NULL;
 	int ret;
 
@@ -527,42 +526,50 @@ static int nvme_scan_subsystem(struct nvme_root *r, const char *name,
 	if (ret < 0)
 		return ret;
 
-	hostnqn = nvme_get_attr(path, "hostnqn");
-	if (hostnqn) {
-		hostid = nvme_get_attr(path, "hostid");
-		h = nvme_lookup_host(r, hostnqn, hostid);
-		free(hostnqn);
-		if (hostid)
-			free(hostid);
-		if (h) {
-			if (h->dhchap_key)
-				free(h->dhchap_key);
-			h->dhchap_key = nvme_get_attr(path, "dhchap_secret");
-			if (h->dhchap_key && !strcmp(h->dhchap_key, "none")) {
-				free(h->dhchap_key);
-				h->dhchap_key = NULL;
-			}
-		}
-	}
-	if (!h)
-		h = nvme_default_host(r);
-	if (!h) {
-		free(path);
-		errno = ENOMEM;
-		return -1;
-	}
 	subsysnqn = nvme_get_attr(path, "subsysnqn");
 	free(path);
 	if (!subsysnqn) {
 		errno = ENODEV;
 		return -1;
 	}
-	s = nvme_lookup_subsystem(h, name, subsysnqn);
-	free(subsysnqn);
+	nvme_for_each_host(r, h) {
+		nvme_for_each_subsystem(h, _s) {
+			/*
+			 * We are always called after nvme_scan_ctrl(),
+			 * so any subsystem we're interested at _must_
+			 * have a name.
+			 */
+			if (!_s->name)
+				continue;
+			if (strcmp(_s->name, name))
+				continue;
+			s = _s;
+		}
+	}
 	if (!s) {
-		errno = ENOMEM;
+		/*
+		 * Subsystem with non-matching controller. odd.
+		 * Create a subsystem with the default host
+		 * and hope for the best.
+		 */
+		nvme_msg(r, LOG_DEBUG, "creating detached subsystem '%s'\n",
+			 name);
+		h = nvme_default_host(r);
+		s = nvme_alloc_subsystem(h, name, subsysnqn);
+		if (!s) {
+			errno = ENOMEM;
+		}
+	} else if (strcmp(s->subsysnqn, subsysnqn)) {
+		nvme_msg(r, LOG_WARNING, "NQN mismatch for subsystem '%s'\n",
+			 name);
+		s = NULL;
+		errno = EINVAL;
 		return -1;
 	}
+	free(subsysnqn);
+	if (!s)
+		return -1;
+
 	nvme_subsystem_scan_namespaces(r, s);
 
 	if (f && !f(s)) {