Dataplane must check whether a block device is in use before launching
the dataplane thread. This is necessary since the thread does not
synchronize with the main loop and I/O requests could cause corruption.
One example is when a drive is added and a block job is started before
hotplugging the virtio-blk-pci adapter. In this case we must not use
dataplane mode.
Cc: qemu-stable@nongnu.org
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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