Looks the above change isn't needed since this blk_mq_start_stopped_hw_queues()
should have been the counterpart of blk_mq_stop_hw_queue() in
blkif_queue_rq().
Removed the patch altogether in v2 as I'm not convinced it is needed.
I've only started reading the series, but to me it seems like the
two places where xen-blkfront currently calls blk_mq_stop_hw_queues
should probably converted, as they are the same category as the other
calls converted in your series.
I'm not familiar enough with the code, I can restore a correct version
of it if it makes sense to you guys...
