From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benny Halevy Subject: Re: [PATCH] sg: increase sglist_len of the sg_scatter_hold structure Date: Thu, 09 Aug 2007 10:33:20 +0300 Message-ID: <46BAC340.4060402@panasas.com> References: <46B600F4.7020601@torque.net> <20070806130944R.fujita.tomonori@lab.ntt.co.jp> <46B8A845.4080106@cs.wisc.edu> <20070808073801U.fujita.tomonori@lab.ntt.co.jp> <46B9F626.9020200@cs.wisc.edu> <46B9FB6B.70501@cs.wisc.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from gw-colo-pa.panasas.com ([66.238.117.130]:21577 "EHLO cassoulet.panasas.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1764900AbXHIHfy (ORCPT ); Thu, 9 Aug 2007 03:35:54 -0400 In-Reply-To: <46B9FB6B.70501@cs.wisc.edu> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Mike Christie Cc: FUJITA Tomonori , dougg@torque.net, tomof@acm.org, linux-scsi@vger.kernel.org, James.Bottomley@SteelEye.com, jens.axboe@oracle.com Mike Christie wrote: > Mike Christie wrote: >> For drivers like sg and st, do mean the the sg list that is passed to >> functions like scsi_execute_async? If we kill that argument, and instead >> have sg.c and other scsi_execute_async callers just call blk helpers >> like blk_rq_map_user then we would not have to worry about drivers like >> sg needing to know about chaining right? I mean sg.c would not every >> interact with a scatterlist. It would just interact with a request and >> the blk helpers map data for it. > > There should be a return there. > > The scatterlist that sg and st interact >> with is bogus. It gets thrown away in scsi_execute_async and is only >> used for book keeping. > > I mean currently the scatterlist that sg and st use is bogus and gets > thrown away. If we convert sg and st to use blk_rq_map_user then those > drivers will not have to interact with a scatterlist at all. I'm not familiar with the dire details but this sounds like a good idea. Benny