The block_set_io_throttle command can look up BlockBackends by the
attached qdev device ID. virtio-blk-pci is a special case because the
actual VirtIOBlock device is the "/virtio-backend" child of the PCI
adapter device.
Add a QMP schema example so clients will know how to use
block_set_io_throttle on the virtio-blk-pci device.
The alternative is to implement some sort of aliasing for qmp_get_blk()
but that is likely to cause confusion and could break future use cases.
Let's not go there.
Cc: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20180117090700.25811-1-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>