Index: uspace/srv/vfs/vfs.h
===================================================================
--- uspace/srv/vfs/vfs.h	(revision 203a0901aaf89da1f59fc324dbbee2c5b07eeed0)
+++ uspace/srv/vfs/vfs.h	(revision 319f4fb1956dc3c4cad77776580e58f8eaa107b2)
@@ -181,4 +181,6 @@
 extern vfs_node_t *vfs_node_get(vfs_lookup_res_t *);
 extern void vfs_node_put(vfs_node_t *);
+extern unsigned vfs_nodes_refcount_sum_get(fs_handle_t, dev_handle_t);
+
 
 #define MAX_OPEN_FILES	128
Index: uspace/srv/vfs/vfs_node.c
===================================================================
--- uspace/srv/vfs/vfs_node.c	(revision 203a0901aaf89da1f59fc324dbbee2c5b07eeed0)
+++ uspace/srv/vfs/vfs_node.c	(revision 319f4fb1956dc3c4cad77776580e58f8eaa107b2)
@@ -231,4 +231,37 @@
 }
 
+struct refcnt_data {
+	/** Sum of all reference counts for this file system instance. */
+	unsigned refcnt;
+	fs_handle_t fs_handle;
+	dev_handle_t dev_handle;
+};
+
+static void refcnt_visitor(link_t *item, void *arg)
+{
+	vfs_node_t *node = hash_table_get_instance(item, vfs_node_t, nh_link);
+	struct refcnt_data *rd = (void *) arg;
+
+	if ((node->fs_handle == rd->fs_handle) &&
+	    (node->dev_handle == rd->dev_handle))
+		rd->refcnt += node->refcnt;
+}
+
+unsigned
+vfs_nodes_refcount_sum_get(fs_handle_t fs_handle, dev_handle_t dev_handle)
+{
+	struct refcnt_data rd = {
+		.refcnt = 0,
+		.fs_handle = fs_handle,
+		.dev_handle = dev_handle
+	};
+
+	fibril_mutex_lock(&nodes_mutex);
+	hash_table_apply(&nodes, refcnt_visitor, &rd);
+	fibril_mutex_unlock(&nodes_mutex);
+
+	return rd.refcnt;
+}
+
 /**
  * @}