diff -Nur btrfs-progs-0.18/btrfsctl.c btrfs-progs-0.18.patched/btrfsctl.c
--- btrfs-progs-0.18/btrfsctl.c	2009-01-17 02:08:19.000000000 +0100
+++ btrfs-progs-0.18.patched/btrfsctl.c	2009-01-18 14:16:25.000000000 +0100
@@ -189,6 +189,10 @@
 
 	if (command == BTRFS_IOC_SCAN_DEV) {
 		fd = open("/dev/btrfs-control", O_RDWR);
+		if (fd < 0) {
+                	fprintf(stderr, "failed to open /dev/btrfs-control\n");
+                       exit(1);
+	        }
 		name = fname;
 	 } else {
 		fd = open_file_or_dir(fname);