+ | NTFSResize -> g#ntfsresize_opts ~force:ntfsresize_force target
+ | BtrfsFilesystemResize ->
+ (* Complicated ... Btrfs forces us to mount the filesystem
+ * in order to resize it.
+ *)
+ assert (Array.length (g#mounts ()) = 0);
+ g#mount_options "" target "/";
+ g#btrfs_filesystem_resize "/";
+ g#umount "/"