Index: uspace/lib/fs/libfs.c
===================================================================
--- uspace/lib/fs/libfs.c	(revision 925a21e74e0c2e08fbcb216e413237c0cb1ac3de)
+++ uspace/lib/fs/libfs.c	(revision b69e4c0e57c95841447ac2ff2a399e6f98d04b10)
@@ -877,4 +877,82 @@
 }
 
+static FIBRIL_MUTEX_INITIALIZE(instances_mutex);
+static LIST_INITIALIZE(instances_list);
+
+typedef struct {
+	service_id_t service_id;
+	link_t link;
+	void *data;
+} fs_instance_t;
+
+int fs_instance_create(service_id_t service_id, void *data)
+{
+	fs_instance_t *inst = malloc(sizeof(fs_instance_t));
+	if (!inst)
+		return ENOMEM;
+
+	link_initialize(&inst->link);
+	inst->service_id = service_id;
+	inst->data = data;
+
+	fibril_mutex_lock(&instances_mutex);
+	list_foreach(instances_list, link) {
+		fs_instance_t *cur = list_get_instance(link, fs_instance_t,
+		    link);
+
+		if (cur->service_id == service_id) {
+			fibril_mutex_unlock(&instances_mutex);
+			free(inst);
+			return EEXIST;
+		}
+
+		/* keep the list sorted */
+		if (cur->service_id < service_id) {
+			list_insert_before(&inst->link, &cur->link);
+			fibril_mutex_unlock(&instances_mutex);
+			return EOK;
+		}
+	}
+	list_append(&inst->link, &instances_list);
+	fibril_mutex_unlock(&instances_mutex);
+
+	return EOK;
+}
+
+int fs_instance_get(service_id_t service_id, void **idp)
+{
+	fibril_mutex_lock(&instances_mutex);
+	list_foreach(instances_list, link) {
+		fs_instance_t *inst = list_get_instance(link, fs_instance_t,
+		    link);
+
+		if (inst->service_id == service_id) {
+			*idp = inst->data;
+			fibril_mutex_unlock(&instances_mutex);
+			return EOK;
+		}
+	}
+	fibril_mutex_unlock(&instances_mutex);
+	return ENOENT;
+}
+
+int fs_instance_destroy(service_id_t service_id)
+{
+	fibril_mutex_lock(&instances_mutex);
+	list_foreach(instances_list, link) {
+		fs_instance_t *inst = list_get_instance(link, fs_instance_t,
+		    link);
+
+		if (inst->service_id == service_id) {
+			list_remove(&inst->link);
+			fibril_mutex_unlock(&instances_mutex);
+			free(inst);
+			return EOK;
+		}
+	}
+	fibril_mutex_unlock(&instances_mutex);
+	return ENOENT;
+}
+
 /** @}
  */
Index: uspace/lib/fs/libfs.h
===================================================================
--- uspace/lib/fs/libfs.h	(revision 925a21e74e0c2e08fbcb216e413237c0cb1ac3de)
+++ uspace/lib/fs/libfs.h	(revision b69e4c0e57c95841447ac2ff2a399e6f98d04b10)
@@ -105,4 +105,8 @@
 extern void fs_node_initialize(fs_node_t *);
 
+extern int fs_instance_create(service_id_t, void *);
+extern int fs_instance_get(service_id_t, void **);
+extern int fs_instance_destroy(service_id_t);
+
 #endif