How does disk locking work in RHEL Virtualization?

• How does libvirt locks the disks to prevent simultaneous access?
• What happens if a disk is setup as shared?
• Red Hat Enterprise Linux 7

To illustrate this, please read the following example:

Let's say we created a disk called shared.qcow2. At this time it is just a disk and is not attached to any VM.

Then we attach this disk to vm 'rhel7', and...