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>
return false;
}
+ /* If dataplane is (re-)enabled while the guest is running there could be
+ * block jobs that can conflict.
+ */
+ if (bdrv_in_use(blk->conf.bs)) {
+ error_report("cannot start dataplane thread while device is in use");
+ return false;
+ }
+
fd = raw_get_aio_fd(blk->conf.bs);
if (fd < 0) {
error_report("drive is incompatible with x-data-plane, "