From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [RFC PATCH 1/3] block: add rq->complete_io hook for request stacking Date: Mon, 3 Mar 2008 18:49:54 +0100 Message-ID: <20080303174953.GE6704@kernel.dk> References: <20080215.172727.39155014.k-ueda@ct.jp.nec.com> <47CC2652.1080601@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <47CC2652.1080601@suse.de> Sender: linux-kernel-owner@vger.kernel.org To: Hannes Reinecke Cc: Kiyoshi Ueda , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, dm-devel@redhat.com, j-nomura@ce.jp.nec.com List-Id: dm-devel.ids 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