From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964857AbWD0Bnm (ORCPT ); Wed, 26 Apr 2006 21:43:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964873AbWD0Bnm (ORCPT ); Wed, 26 Apr 2006 21:43:42 -0400 Received: from rtr.ca ([64.26.128.89]:44952 "EHLO mail.rtr.ca") by vger.kernel.org with ESMTP id S964857AbWD0Bnl (ORCPT ); Wed, 26 Apr 2006 21:43:41 -0400 Message-ID: <445021B8.3070705@rtr.ca> Date: Wed, 26 Apr 2006 21:43:20 -0400 From: Mark Lord User-Agent: Thunderbird 1.5.0.2 (X11/20060420) MIME-Version: 1.0 To: Andrew Morton Cc: James.Bottomley@SteelEye.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Jens Axboe Subject: Re: [PATCH] drivers/scsi/sd.c: fix uninitialized variable in handling medium errors References: <200604261627.29419.lkml@rtr.ca> <1146092161.12914.3.camel@mulgrave.il.steeleye.com> <20060426161444.423a8296.akpm@osdl.org> <44500033.3010605@rtr.ca> <20060426163536.6f7bff77.akpm@osdl.org> In-Reply-To: <20060426163536.6f7bff77.akpm@osdl.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: > Mark Lord wrote: >>> That's if we think -stable needs this fixed. >> Let's say a bunch of read bio's get coalesced into a single >> 200+ sector request. This then fails on one single bad sector >> out of the 200+. Without the patch, there is a very good chance >> that sd.c will simply fail the entire request, all 200+ sectors. >> >> With the patch, it will fail the first block, and then retry >> the remaining blocks. And repeat this until something works, >> or until everything has failed one by one. > > Yowch. I have the feeling that this'll take our EIO-handling time from > far-too-long to far-too-long*200. That's how it always used to work (eg. SUSE9 2.6.5+ kernels; Jens?). >> What I need to have happen when a request is failed due to bad-media, >> is have it split the request into a sequence of single-block requests >> that are passed to the LLD one at a time. The ones with real bad >> sectors will then be independently failed, and the rest will get done. >> >> Much better. Much more complex. >> >> I'm thinking about something like that, just not sure whether to put it >> (initially) in libata, sd.c, or the block layer. > > block, I suspect. My DVD trauma was IDE-induced. Jens is mulling the > problem - I'd suggest you coordinate with him. I've been pinging Jens about it for a couple of weeks now; no response. > It would be a good thing to fix. > > It's moderately hard to test, though. Easy enough for DVDs and CDs, but > it's harder to take a marker pen to a hard drive. I have a bunch of "pre-marked" SATA drives here just for the purpose.. Cheers