[Qemu-devel] [PATCH v2 0/2] Disallow snapshots if the overlay doesn't support backing files

[Alberto Garcia <berto@igalia.com>]

We are currently allowing snapshots in cases 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' } }

This patch forbids snapshots if the overlay node does not support
backing files.

Regards,

Berto

v2:
- Disallow snapshots if new_bs->drv->supports_backing is false [Max]

v1: https://lists.gnu.org/archive/html/qemu-devel/2015-10/msg06875.html
- Initial version.

Alberto Garcia (2):
  block: Disallow snapshots if the overlay doesn't support backing files
  block: test 'blockdev-snapshot' using a file BDS as the overlay

 blockdev.c                 |  5 +++++
 tests/qemu-iotests/085     | 12 +++++++++++-
 tests/qemu-iotests/085.out |  4 ++++
 3 files changed, 20 insertions(+), 1 deletion(-)

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2.6.1