On 11/28/18 12:16 AM, Christoph Hellwig wrote: > On Mon, Nov 26, 2018 at 09:35:51AM -0700, Jens Axboe wrote: >> blk-mq passes information to the hardware about any given request being >> the last that we will issue in this sequence. The point is that hardware >> can defer costly doorbell type writes to the last request. But if we run >> into errors issuing a sequence of requests, we may never send the request >> with bd->last == true set. For that case, we need a hook that tells the >> hardware that nothing else is coming right now. >> >> For failures returned by the drivers ->queue_rq() hook, the driver is >> responsible for flushing pending requests, if it uses bd->last to >> optimize that part. This works like before, no changes there. >> >> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> > > This looks fine, but normally I would only add the method together with > the actual user.. I included the two hunks from patch 7 in this one, so there's a real use (and fix) with it. -- Jens Axboe
