tree: make nvme_subsystem_scan_namespace() idempotent

When issuing a rescan the list of namespaces is not cleared, so
just blindly adding new entries might not yield the expected result.
This patch clears out old entries from the subsystem namespace list
before adding new ones, ensuring that we only ever have one namespace
with a given name in the list of subsystem namespaces.

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

Author: hreinecke

src/nvme/tree.c

@@ -1890,7 +1890,7 @@ static void nvme_subsystem_set_ns_path(nvme_subsystem_t s, nvme_ns_t n)
 static int nvme_subsystem_scan_namespace(nvme_root_t r, nvme_subsystem_t s,
 		char *name, nvme_scan_filter_t f, void *f_args)
 {
-	struct nvme_ns *n;
+	struct nvme_ns *n, *_n, *__n;
 
 	nvme_msg(r, LOG_DEBUG, "scan subsystem %s namespace %s\n",
 		 s->name, name);
@@ -1904,6 +1904,19 @@ static int nvme_subsystem_scan_namespace(nvme_root_t r, nvme_subsystem_t s,
 		__nvme_free_ns(n);
 		return 0;
 	}
+	nvme_subsystem_for_each_ns_safe(s, _n, __n) {
+		struct nvme_path *p, *_p;
+
+		if (strcmp(n->name, _n->name))
+			continue;
+		/* Detach paths */
+		nvme_namespace_for_each_path_safe(_n, p, _p) {
+			list_del_init(&p->nentry);
+			p->n = NULL;
+		}
+		list_head_init(&_n->paths);
+		__nvme_free_ns(_n);
+	}
 	n->s = s;
 	list_add(&s->namespaces, &n->entry);
 	nvme_subsystem_set_ns_path(s, n);