Merge remote-tracking branch 'stefanha/block' into staging

Merge remote-tracking branch 'stefanha/block' into staging

# By Stefan Hajnoczi (4) and others
# Via Stefan Hajnoczi
* stefanha/block:
  dataplane: refuse to start if device is already in use
  dataplane: enable virtio-blk x-data-plane=on live migration
  migration: fix spice migration
  migration: notify migration state before starting thread
  block: Repair the throttling code.
  gluster: Add image resize support

Message-id: 1375112172-24863-1-git-send-email-stefanha@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>