From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [PATCH RFC 0/4] use scatter lists for all block pc requests and simplify hw handlers Date: Tue, 07 Jun 2005 15:38:38 -0400 Message-ID: <1118173118.4791.17.camel@mulgrave> References: <1117847972.23638.62.camel@mina> <20050607180716.GA8172@suse.de> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from stat16.steeleye.com ([209.192.50.48]:63173 "EHLO hancock.sc.steeleye.com") by vger.kernel.org with ESMTP id S261982AbVFGUnO (ORCPT ); Tue, 7 Jun 2005 16:43:14 -0400 In-Reply-To: <20050607180716.GA8172@suse.de> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Jens Axboe Cc: Mike Christie , device-mapper development , linux-scsi 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. I'm still not sure we have it entirely correct, though. Something still needs to be done about the queue alignment constraints, so bio_copy_... might need to be part of this API. Also, Jens, this looks wrong (from ll_rw_blk.c around line 2131): if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q))) The alignment surely wants to be only on the start buffer (otherwise we'll get spurious copies in variable length commands (like inquiries)? James