On Thu, Apr 20, 2017 at 09:03:47AM +0800, Ming Lei wrote: > If we don't need to reserve tag for internal command, I am happy > to fix it in the interim. However, the mtip32xx driver has to > ask blk-mq to reserve the tag zero for internal command. Then > if we can't allow the driver to use that reserved tag, it looks > quite awkward, doesn't it? It doesn't. Just offset the hardware tags by 1 from the blk-mq tags. But I'm pretty sure the hardware wouldn't require a specific tag for the internal ops.