# Test of live blockcopy using a live VM with the backing chain:
# base <- snap1 <- snap2
----------
1. Create a chain: base <-- snap1 <-- snap2
    $ qemu-img create -f qcow2 base.qcow2 1G
    $ qemu-img create -f qcow2 -b base.qcow2 \
        -o backing_fmt=qcow2 snap1.qcow2
    $ qemu-img create -f qcow2 -b snap1.qcow2 \
        -o backing_fmt=qcow2 snap2.qcow2
----------

1.1 Add some content (in each disk image):
----------
$ guestfish -a /path/disk.qcow2
><fs> run
><fs> part-disk /dev/sda mbr
><fs> mkfs ext4 /dev/sda1
><fs> list-filesystems 
><fs> mount /dev/sda1 /
><fs> touch /foo
><fs> touch /bar
><fs> ls /
bar
foo
lost+found
><fs>exit
----------


2. Provide appropriate SELinux context to the disk images.

    $ chcon -t svirt_image_t base.qcow2 snap1.qcow2 snap2.qcow2


3. Enumerate the backing chain information

    $ qemu-img info --backing-chain /export/vmimages/snap2.qcow2


4. Create a persistent libvirt domain:
----------
$ cat <<EOF > /etc/libvirt/qemu/vm1.xml
<domain type='kvm'>
  <name>vm1</name>
  <memory unit='MiB'>512</memory>
  <vcpu>1</vcpu>
  <os>
    <type arch='x86_64'>hvm</type>
  </os>
  <devices>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/export/blockcopy-test/snap2.qcow2'/>
      <target dev='vda' bus='virtio'/>
    </disk>
  </devices>
</domain>
EOF
----------

4.1 Define the above XML:

    $ virsh define /etc/libvirt/qemu/vm1.xml
    $ virsh start vm1

4.2 Take a backup of the guest XML, and make the domain transient:

    $ virsh dumpxml --inactive vm1 > /var/tmp/vm1.xml
    $ virsh undefine vm1

5. Create an existing destination file to which contents of snap2 can be
   copied:

    $ cp base.qcow2 snap1.qcow2 /export/backups/
    $ mv /export/backups/snap1.qcow2 /export/backups/copy-vm1.qcow2

6. Abort any block operations on the current block device:

    $ virsh blockjob --abort vm1 vda

7. Perform blockcopy (which should get contents of snap2 into snap1,
   OVERWRITING contents of snap1):

    $ virsh blockcopy --domain vm1 vda \
        /export/blockcopy-test/backups/copy-vm1.qcow2 --shallow \
        --reuse-external --wait --verbose --finish
    Block Copy: [100 %]
    Now in mirroring phase

    $ echo $?
    0

7.1 Make the domain persistent again:

    $ virsh define /var/tmp/vm1.xml

8. Enumerate the backing chain:

    $ qemu-img info --backing-chain ./backups/copy-vm1.qcow2 
    image: ./backups/copy-vm1.qcow2
    file format: qcow2
    virtual size: 193K (197120 bytes)
    disk size: 516K
    cluster_size: 65536
    backing file: base.qcow2 (actual path: ./backups/base.qcow2)
    backing file format: raw
    Format specific information:
        compat: 1.1
        lazy refcounts: false
    
    image: ./backups/base.qcow2
    file format: raw
    virtual size: 193K (197120 bytes)
    disk size: 196K

$ virsh blockjob --abort vm1 vda