This fixes bdrv_invalidate_cache_all() for some kinds of graphs where
part of the nodes are active and others are inactive. This is a scenario
that happens when libvirt takes an external snapshot with VM state.

This was reported in:
https://bugzilla.redhat.com/show_bug.cgi?id=1781637
('qemu crashed when do mem and disk snapshot')

Based-on: <20191216170857.11880-1-kwolf@redhat.com>
('iotests: Remove duplicated blockdev_create()')

Kevin Wolf (3):
  block: Activate recursively even for already active nodes
  hmp: Allow using qdev ID for qemu-io command
  iotests: Test external snapshot with VM state

 block.c                    | 50 +++++++++++------------
 monitor/hmp-cmds.c         | 28 ++++++++-----
 hmp-commands.hx            |  8 ++--
 tests/qemu-iotests/280     | 83 ++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/280.out | 50 +++++++++++++++++++++++
 tests/qemu-iotests/group   |  1 +
 6 files changed, 181 insertions(+), 39 deletions(-)
 create mode 100755 tests/qemu-iotests/280
 create mode 100644 tests/qemu-iotests/280.out

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2.20.1