Date: Mon, 3 Mar 2008 18:49:54 +0100
From: Jens Axboe <jens.axboe@oracle.com>
To: Hannes Reinecke <hare@suse.de>
Cc: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>, linux-kernel@vger.kernel.org,
       linux-scsi@vger.kernel.org, dm-devel@redhat.com, j-nomura@ce.jp.nec.com
Subject: Re: [RFC PATCH 1/3] block: add rq->complete_io hook for request stacking
Message-ID: <20080303174953.GE6704@kernel.dk>
References: <20080215.172727.39155014.k-ueda@ct.jp.nec.com> <47CC2652.1080601@suse.de>
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On Mon, Mar 03 2008, Hannes Reinecke wrote:
> Hi Kiyoshi,
> 
> Kiyoshi Ueda wrote:
> > This patch adds ->complete_io() hook for request stacking.
> > Request stacking drivers (such as request-based dm) can set
> > a callback for completion.
> > (The hook is not called in blk_end_io(), since request-based dm uses
> >  it for clone completion in the following appendix patches.)
> > 
> [ .. ]
> I would rather have rq->complete_io() to be pointing to blk_end_io in the
> default case, this way rq->complete_io() would always be valid and we
> would be saving us the if() clause.

The whole point of this ->complete_io() thread is that we cannot use the
above approach, before all drivers are converted from using
__blk_end_request() to blk_end_request(). And that requires some work.

-- 
Jens Axboe

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