#!/usr/bin/python3

import btrfs
import sys

if len(sys.argv) < 2:
    print("Usage: {} <mountpoint>".format(sys.argv[0]))
    sys.exit(1)


def subvolumes_inside(fs, parent_tree):
    min_key = btrfs.ctree.Key(parent_tree, btrfs.ctree.ROOT_REF_KEY, 0)
    max_key = btrfs.ctree.Key(parent_tree, btrfs.ctree.ROOT_REF_KEY + 1, 0) - 1
    for header, data in btrfs.ioctl.search_v2(fs.fd, 1, min_key, max_key):
        ref = btrfs.ctree.RootRef(header, data)
        path = (btrfs.ioctl.ino_lookup(fs.fd, ref.parent_tree, ref.dirid).name_bytes +
                ref.name).decode()
        yield ref.tree, path


def print_subvolumes_inside(fs, parent_tree, parent_path):
    for tree, path in subvolumes_inside(fs, parent_tree):
        sub_path = "{}/{}".format(parent_path, path)
        print("ID {} parent {} path {}".format(tree, parent_tree, sub_path))
        print_subvolumes_inside(fs, tree, sub_path)


with btrfs.FileSystem(sys.argv[1]) as fs:
    print_subvolumes_inside(fs, 5, '')