#!/bin/bash

function clean_up {
umount mntpoint
rmdir mntpoint
losetup -d $DEV4
losetup -d $DEV3
losetup -d $DEV2
losetup -d $DEV1
rm disk1 disk2 disk3 disk4
exit
}

trap clean_up SIGHUP SIGINT SIGTERM EXIT

truncate -s 20G disk1 && \
truncate -s 20G disk2 && \
truncate -s 10G disk3 && \
truncate -s 10G disk4 && \
DEV1=$(losetup -f --show disk1) && \
DEV2=$(losetup -f --show disk2) && \
DEV3=$(losetup -f --show disk3) && \
DEV4=$(losetup -f --show disk4) && \
mkfs.btrfs -m raid1 -d raid1 $DEV1 $DEV2 && \
mkdir mntpoint && \
mount $DEV1 mntpoint -odevice=$DEV2 && \
dd if=/dev/zero of=mntpoint/testfile bs=1M count=17000 && \
umount mntpoint && \
btrfs filesystem show $DEV1 && \
losetup -d $DEV2 && \
mount $DEV1 mntpoint -odegraded && \
btrfs device add $DEV3 $DEV4 mntpoint && \
btrfs device delete missing mntpoint
btrfs filesystem show $DEV1