xen/blkback: Don't trust the handle from the frontend.
The 'handle' is the device that the request is from. For the life-time of the ring we copy it from a request to a response so that the frontend is not surprised by it. But we do not need it - when we start processing I/Os we have our own 'struct phys_req' which has only most essential information about the request. In fact the 'vbd_translate' ends up over-writing the preq.dev with a value from the backend. This assignment of preq.dev with the 'handle' value is superfluous so lets not do it. Cc: firstname.lastname@example.org Acked-by: Jan Beulich <email@example.com> Acked-by: Ian Campbell <firstname.lastname@example.org> Signed-off-by: Konrad Rzeszutek Wilk <email@example.com>