[Libguestfs] Help: how to change default disk size when doing test

Hi Rich, I am developing a patch for btrfs enhancement: btrfs-convert. When I do test, run: make check tests, in dir libguestfs/tests/c-api, I got these error: 0/516 test_btrfs_convert_0 libguestfs: error: btrfs_convert: /dev/sda1: block size is too small conversion aborted. FAIL: test_btrfs_convert_0 I also ran "btrfs-convert" command to deal with a 100MB img file outside the guestfish, I got the same err msg, so it is a litmitation of btrfs-convert So my question is: How to changed the default disk size, when do: make check tests Yours sincerely, Pino