Now that block_resize acquires the AioContext we can safely allow
resizing the disk.
Reported-by: Andrey Korolyov <andrey@xdel.ru> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>