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

# Arg 1: -rf
# Arg 2: /testbtrfs/backups/hourly.4/

# echo 1: $1  2: $@

# Try to delete the given path with btrfs subvolume delete first
# Check if inode number == 256 (all subvolumes have inode number 256)
if [  "$1" = "-rf"  -a  "$3" = "" -a $(stat --printf='%i' $2) -eq 256 ]; then
        # "trying to delete with btrfs"
        btrfs subvolume delete $2
        error=$?
        # if this fails fall back to normal rm (this shoudn't be needed anymore because of the inode check)
        if [ $error -eq 13 ]; then
                # EC 13 => The directory specified is no subvolume
                rm $@
        elif [ $error -ne 0 ]; then
                echo Error while deleting with btrfs $?
        fi
else
        rm $@
fi