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Jens Axboe authored
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. Reviewed-by:
Omar Sandoval <osandov@fb.com> Reviewed-by:
Ming Lei <ming.lei@redhat.com> Reviewed-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
Jens Axboe <axboe@kernel.dk>
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