From mboxrd@z Thu Jan 1 00:00:00 1970 From: Douglas Gilbert Subject: Re: [PATCH RFC 0/4] use scatter lists for all block pc requests and simplify hw handlers Date: Wed, 08 Jun 2005 13:00:45 +1000 Message-ID: <42A65F5D.6060805@torque.net> References: <1117847972.23638.62.camel@mina> <20050607180716.GA8172@suse.de> <1118173118.4791.17.camel@mulgrave> Reply-To: dougg@torque.net Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from zorg.st.net.au ([203.16.233.9]:56220 "EHLO borg.st.net.au") by vger.kernel.org with ESMTP id S262078AbVFHDAZ (ORCPT ); Tue, 7 Jun 2005 23:00:25 -0400 In-Reply-To: <1118173118.4791.17.camel@mulgrave> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: Jens Axboe , Mike Christie , linux-scsi , Kai.Makisara@kolumbus.fi James Bottomley wrote: > On Tue, 2005-06-07 at 20:07 +0200, Jens Axboe wrote: > >>I've slowly been doing the same thing in other places in the kernel and >>this bit has been talked about between James and I for at least a year >>or two. > > > Yes, it's long been a dream of mine to eliminate at least struct > scsi_request and just use block struct request for everything in the > SCSI layer. > > The most pleasing aspect of this will be getting rid of the dma mapping > duplications in st and sg. James, A "char_uld" library that st, sg, ch and the proposed OSD ULDs could tap into, would cut the duplication. As you can see, Kai and I have shared implementations in this area but had no mechanism for sharing the actual code. An idea I had was to flag what mechanism inserted a command onto a request queue and when a blk_pc_request() follows a blk_pc_request() then use FIFO order for the second one. Doug Gilbert