A btrfs-progs test case, showing a backup+sync setup between two (or more) PCs with an external drive.

057-reverse-receive_test.sh

#!/bin/bash
#
# Receive in reverse direction must not throw an error if it can find an earlier "sent" parent.
# In general, shows a backup+sync setup between two (or more) PCs with an external drive.

source "$TEST_TOP/common"

check_prereq mkfs.btrfs
check_prereq btrfs
check_global_prereq dd

declare -a roots
i_pc1=1
# An external drive used to backup and carry profile.
i_ext=2
i_pc2=3
roots[$i_pc1]="$TEST_MNT/pc1"
roots[$i_ext]="$TEST_MNT/external"
roots[$i_pc2]="$TEST_MNT/pc2"

setup_root_helper
mkdir -p ${roots[@]}
setup_loopdevs 3
prepare_loopdevs
for i in `seq 3`; do
	TEST_DEV=${loopdevs[$i]}
    TEST_MNT="${roots[$i]}"
    run_check_mkfs_test_dev
    run_check_mount_test_dev
    run_check $SUDO_HELPER mkdir -p "$TEST_MNT/.snapshots"
done

run_check_create_file()
{
    run_check $SUDO_HELPER dd if=/dev/urandom bs=2K count=1 "of=${roots[$1]}/profile/$2"
}
run_check_copy_snapshot_with_diff()
{
    _mktemp_local send.data
    run_check $SUDO_HELPER "$TOP/btrfs" send -f send.data -p "${roots[$1]}/.snapshots/$2" "${roots[$1]}/.snapshots/$3"
    run_check $SUDO_HELPER "$TOP/btrfs" receive -f send.data "${roots[$4]}/.snapshots"
}
run_check_backup_profile()
{
    run_check $SUDO_HELPER "$TOP/btrfs" subvolume snapshot -r "${roots[$1]}/profile" "${roots[$1]}/.snapshots/$3"
    run_check_copy_snapshot_with_diff $1 $2 $3 $i_ext
    # Don't keep old snapshot in pc
    run_check $SUDO_HELPER "$TOP/btrfs" subvolume delete "${roots[$1]}/.snapshots/$2"
}
run_check_restore_profile()
{
    run_check $SUDO_HELPER "$TOP/btrfs" subvolume snapshot "${roots[$1]}/.snapshots/$2" "${roots[$1]}/profile"
}
run_check_copy_fresh_backup_and_replace_profile()
{
    run_check_copy_snapshot_with_diff $i_ext $2 $3 $1
    # IRL, it would be a nice idea to make a backup snapshot before deleting.
    run_check $SUDO_HELPER "$TOP/btrfs" subvolume delete "${roots[$1]}/profile"
    run_check_restore_profile $1 $3
    # Don't keep old snapshot in pc
    run_check $SUDO_HELPER "$TOP/btrfs" subvolume delete "${roots[$1]}/.snapshots/$2"
}


run_check $SUDO_HELPER "$TOP/btrfs" subvolume create "${roots[$i_pc1]}/profile"
run_check_create_file $i_pc1 day1
run_check $SUDO_HELPER "$TOP/btrfs" subvolume snapshot -r "${roots[$i_pc1]}/profile" "${roots[$i_pc1]}/.snapshots/day1"
_mktemp_local send.data
run_check $SUDO_HELPER "$TOP/btrfs" send -f send.data "${roots[$i_pc1]}/.snapshots/day1"
run_check $SUDO_HELPER "$TOP/btrfs" receive -f send.data "${roots[$i_ext]}/.snapshots"

run_check_create_file $i_pc1 day2
run_check_backup_profile $i_pc1 day1 day2

_mktemp_local send.data
run_check $SUDO_HELPER "$TOP/btrfs" send -f send.data "${roots[$i_ext]}/.snapshots/day2"
run_check $SUDO_HELPER "$TOP/btrfs" receive -f send.data "${roots[$i_pc2]}/.snapshots"
run_check_restore_profile $i_pc2 day2
run_check_create_file $i_pc2 day3
run_check_backup_profile $i_pc2 day2 day3

run_check_create_file $i_pc2 day4
run_check_backup_profile $i_pc2 day3 day4

run_check_copy_fresh_backup_and_replace_profile $i_pc1 day2 day4
run_check_create_file $i_pc1 day5
run_check_backup_profile $i_pc1 day4 day5

run_check_copy_fresh_backup_and_replace_profile $i_pc2 day4 day5
run_check_create_file $i_pc2 day6
run_check_backup_profile $i_pc2 day5 day6

run_check_umount_test_dev ${loopdevs[@]}
rmdir ${roots[@]}
rm -f send.data
cleanup_loopdevs