a small shell script that can be used within rsnapshot as cmd_rm. It provides snapshots generated with btrfs instead of hard-links

rsnapshot_plug_rm_btrfs

#!/bin/sh
# Original source: https://gist.github.com/wwerther/1306189
# Original documentation: http://web.archive.org/web/20190910001551/http://it.werther-web.de/2011/10/23/migrate-rsnapshot-based-backup-to-btrfs-snapshots
# Modified version: https://gist.github.com/zvpunry/af667816d63df089cd34f81458598b6f
#
# Arg 1: -rf
# Arg 2: /testbtrfs/backups/hourly.4/

# echo 1: $1  2: $@

PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

# Try to delete the given path with btrfs subvolume delete first
# if this fails fall back to normal rm
if test "$1" = "-rf" -a  -z "$3"
then
	btrfs property set -ts "$2" ro false
	btrfs subvolume delete -C "$2" > /dev/null || rm -rf "$2"
else
        rm "$@"
fi