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Date: Wed, 19 Apr 2017 21:54:08 -0700
From: Christoph Hellwig <hch@infradead.org>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@fb.com>, linux-block@vger.kernel.org,
        Christoph Hellwig <hch@infradead.org>,
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Subject: Re: [PATCH 0/4] blk-mq-sched: allow to use hw tag for sched
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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.