add defrag ioctl
diff --git a/btrfsctl.c b/btrfsctl.c
index ae2f27b..4dfc42b 100644
--- a/btrfsctl.c
+++ b/btrfsctl.c
@@ -77,6 +77,12 @@
 				exit(1);
 			}
 			command = BTRFS_IOC_SNAP_CREATE;
+		} else if (strcmp(av[i], "-d") == 0) {
+			if (i >= ac - 1) {
+				fprintf(stderr, "-d requires an arg");
+				print_usage();
+			}
+			command = BTRFS_IOC_DEFRAG;
 		}
 	}
 	if (command == 0) {
@@ -102,7 +108,10 @@
 		perror("open");
 		exit(1);
 	}
-	strcpy(args.name, name);
+	if (name)
+		strcpy(args.name, name);
+	else
+		args.name[0] = '\0';
 	ret = ioctl(fd, command, &args);
 	printf("ioctl returns %d\n", ret);
 	return 0;
diff --git a/ioctl.h b/ioctl.h
index 23bed48..8bc47de 100644
--- a/ioctl.h
+++ b/ioctl.h
@@ -28,6 +28,6 @@
 
 #define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \
 				   struct btrfs_ioctl_vol_args)
-#define BTRFS_IOC_ADD_DISK _IOW(BTRFS_IOCTL_MAGIC, 2, \
+#define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, \
 				   struct btrfs_ioctl_vol_args)
 #endif
diff --git a/mkfs.c b/mkfs.c
index ac99049..bd66467 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -225,6 +225,7 @@
 	btrfs_set_inode_nblocks(inode_item, 1);
 	btrfs_set_inode_mode(inode_item, S_IFDIR | 0755);
 
+	// memset(&root_item, 0, sizeof(root_item));
 	btrfs_set_root_dirid(&root_item, 0);
 	btrfs_set_root_refs(&root_item, 1);
 	btrfs_set_disk_key_offset(&item.key, 0);
diff --git a/print-tree.c b/print-tree.c
index 9df4379..60deda5 100644
--- a/print-tree.c
+++ b/print-tree.c
@@ -96,6 +96,16 @@
 				(unsigned long long)btrfs_root_blocknr(ri),
 				(unsigned long long)btrfs_root_dirid(ri),
 				btrfs_root_refs(ri));
+			if (1 || btrfs_root_refs(ri) == 0) {
+				struct btrfs_key drop_key;
+				btrfs_disk_key_to_cpu(&drop_key,
+						      &ri->drop_progress);
+				printf("\t\tdrop key %Lu %x %Lu level %d\n",
+				       (unsigned long long)drop_key.objectid,
+				       drop_key.flags,
+				       (unsigned long long)drop_key.offset,
+				       ri->drop_level);
+			}
 			break;
 		case BTRFS_EXTENT_ITEM_KEY:
 			ei = btrfs_item_ptr(l, i, struct btrfs_extent_item);