This is a continuation of the nowait support which was incorporated a while back. We introduced REQ_NOWAIT which would return immediately if the call would block at the block layer. Request based-devices do not wait. However, bio based devices (the ones which exclusively call make_request_fn) need to be trained to handle REQ_NOWAIT. This effort covers the devices under MD and DM which would block for any reason. If there should be more devices or situations which need to be covered, please let me know. -- Goldwyn
