#!/bin/bash

mylog() {
        echo "$(date) : $*"
}

my_losetup() {
        local idx=$1
        losetup | grep -q /dev/loop$idx || losetup /dev/loop$idx /backup/testing/disk$idx
}

btrfs_change() {

        umount /testbtrfs
        local add_nr=$1
        local del_nr=$2
        mylog "changing btrfs to enabled: $add_nr disabled: $del_nr"
        my_losetup $add_nr
        losetup -d /dev/loop$del_nr
        mount -o rw,degraded /dev/loop$add_nr /testbtrfs

}

btrfs_mount_clean() {
        umount /testbtrfs
        my_losetup 0
        my_losetup 1
        mount /dev/loop0 /testbtrfs
}

do_write() {
        echo "$(date) : v$1" >>/testbtrfs/testdir1/testfile
}

i=1
while :;do 
        btrfs_mount_clean
        btrfs_change 1 0
        do_write "$i"
        btrfs_mount_clean
        btrfs_change 0 1
        do_write "$((i+1))"
        ((i=i+2))
done