commit 08b24cfe3765f4b739700778814048e7d9a045fe
author Alberto Garcia <berto@igalia.com> Tue Nov 03 12:32:35 2015 +0200
committer Kevin Wolf <kwolf@redhat.com> Wed Nov 11 16:25:48 2015 +0100
tree ece881c5e0c550972730db1419cbc0c846335d6b
parent a0d64a61db602696f4f1895a890c65eda5b3b618

block: Disallow snapshots if the overlay doesn't support backing files

This addresses scenarios like this one:

  { 'execute': 'blockdev-add', 'arguments':
    { 'options': { 'driver': 'qcow2',
                   'node-name': 'new0',
                   'file': { 'driver': 'file',
                             'filename': 'new.qcow2',
                             'node-name': 'file0' } } } }

  { 'execute': 'blockdev-snapshot', 'arguments':
    { 'node': 'virtio0',
      'overlay': 'file0' } }

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>