Index: uspace/lib/fs/libfs.h
===================================================================
--- uspace/lib/fs/libfs.h	(revision c84146d3591766f01374dd9dbf6a71f9db5f7055)
+++ uspace/lib/fs/libfs.h	(revision b51cf2cfbf7533cc494e6a1795d62f5fbd481c87)
@@ -93,7 +93,7 @@
 	bool (* is_file)(fs_node_t *);
 	service_id_t (* service_get)(fs_node_t *);
-	uint32_t (* size_block)(service_id_t);
-	uint64_t (* total_block_count)(service_id_t);
-	uint64_t (* free_block_count)(service_id_t);
+	int (* size_block)(service_id_t, uint32_t *);
+	int (* total_block_count)(service_id_t, uint64_t *);
+	int (* free_block_count)(service_id_t, uint64_t *);
 } libfs_ops_t;