From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755671AbYHGRPn (ORCPT ); Thu, 7 Aug 2008 13:15:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755203AbYHGRPQ (ORCPT ); Thu, 7 Aug 2008 13:15:16 -0400 Received: from fg-out-1718.google.com ([72.14.220.156]:24876 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755115AbYHGRPO (ORCPT ); Thu, 7 Aug 2008 13:15:14 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:subject:date:user-agent:cc:references:in-reply-to :mime-version:content-disposition:message-id:content-type :content-transfer-encoding; b=XTFFMbfOrbcp0mXEdFtex1JoYiCHDx2HPkC5Xumbuan/f578PCMlF3JveZe06Pw7y0 OnkNY4SAcq0knpEaiUF/wPnbiTJ8ZESe3jFCV/q2cNgBvlvl6tKweIgdzQH0TZFcRV6u 1gNDZYTS91hCL8Qcd8Wb/OENQPvesIr2Ql0xU= From: Bartlomiej Zolnierkiewicz To: petkovbb@gmail.com Subject: Re: [PATCH] ide-floppy: use scatterlists for pio transfers Date: Thu, 7 Aug 2008 18:57:09 +0200 User-Agent: KMail/1.9.9 Cc: linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org References: <20080805051113.GA15834@gollum.tnic> <200808061805.01126.bzolnier@gmail.com> <20080806193056.GA31312@gollum.tnic> In-Reply-To: <20080806193056.GA31312@gollum.tnic> MIME-Version: 1.0 Content-Disposition: inline Message-Id: <200808071857.09609.bzolnier@gmail.com> Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 06 August 2008, Borislav Petkov wrote: > On Wed, Aug 06, 2008 at 06:05:00PM +0200, Bartlomiej Zolnierkiewicz wrote: > > > > Hi, > > > > On Tuesday 05 August 2008, Borislav Petkov wrote: > > > Hi Bart, > > > > > > here's my first stab at using scatterlists in ide-floppy. I've adapted your > > > ide-scsi version to fit in here. The change here is that i use pc->b_count as > > > a sort-of completion counter to know when i'm at the end of the sg element and > > > be able to switch to the next/finish transfer. I've tested the patch with the > > > Iomega ZIP drive i have here - it works. We should do some more testing first > > > though, before sending it upstream. > > > > [...] > > > > > @@ -569,7 +577,7 @@ static void idefloppy_create_rw_cmd(idefloppy_floppy_t *floppy, > > > memcpy(rq->cmd, pc->c, 12); > > > > > > pc->rq = rq; > > > - pc->b_count = cmd == READ ? 0 : rq->bio->bi_size; > > > + pc->b_count = 0; > > > if (rq->cmd_flags & REQ_RW) > > > pc->flags |= PC_FLAG_WRITING; > > > pc->buf = NULL; > > > > Don't we also need to zero pc->b_count in idefloppy_blockpc_cmd()? > > > > [ idefloppy_init_pc() clears whole pc so ->b_count assignment > > to zero is not strictly necessary ] > > We probably should and i should've probably hit that during testing and maybe > hit an OOPS along that path but we don't do REQ_TYPE_BLOCK_PC in ide-floppy > yet, as it appears, and since idefloppy_blockpc_cmd() is only called when > blk_pc_request(rq) that's why this one doesn't matter here. We should consider > it though when we convert to using BLOCK_PC type rq's. Unless somebody tries to use SG_IO ioctl (however I don't know if anybody has actually ever tried so it as well may be that it hasn't worked before...). Anyway I applied the patch and fixed pc->b_count while at it (just-in-case).