From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754355Ab0I2Asg (ORCPT ); Tue, 28 Sep 2010 20:48:36 -0400 Received: from comms2.zx.nl ([194.187.76.142]:54779 "EHLO comms2.zx.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750943Ab0I2Asf (ORCPT ); Tue, 28 Sep 2010 20:48:35 -0400 MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-type: text/plain; CHARSET=US-ASCII Subject: Re: [PATCH 1/1] um: ubd: Fix data corruption From: Janjaap Bos To: Jens Axboe Cc: Chris Frey , Richard Weinberger , Andrew Morton , "linux-kernel@vger.kernel.org" , "jdike@addtoit.com" , "user-mode-linux-devel@lists.sourceforge.net" , "user-mode-linux-user@lists.sourceforge.net" , "geert@linux-m68k.org" , "martin.petersen@oracle.com" , "adobriyan@gmail.com" , "syzop@vulnscan.org" In-reply-to: <4CA275CE.6060401@fusionio.com> References: <1285710456-4435-1-git-send-email-richard@nod.at> <20100928150000.f007f43e.akpm@linux-foundation.org> <201009290013.11332.richard@nod.at> <20100928225202.GA30352@foursquare.net> <4CA275CE.6060401@fusionio.com> Date: Wed, 29 Sep 2010 02:48:28 +0200 Message-id: <1285721308.9775.3.camel@voyager> X-Mailer: Evolution 2.28.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2010-09-29 at 08:10 +0900, Jens Axboe wrote: > It looks like that if we need to restart the requeue, then > we use the initial position and not the current index. Does > this help? > > diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c > index 1bcd208..81ee063 100644 > --- a/arch/um/drivers/ubd_kern.c > +++ b/arch/um/drivers/ubd_kern.c > @@ -162,7 +162,7 @@ struct ubd { > spinlock_t lock; > struct scatterlist sg[MAX_SG]; > struct request *request; > - int start_sg, end_sg; > + int start_sg, end_sg, rq_off; > }; > > #define DEFAULT_COW { \ > @@ -187,6 +187,7 @@ struct ubd { > .request = NULL, \ > .start_sg = 0, \ > .end_sg = 0, \ > + .rq_off = 0, \ > } > > /* Protected by ubd_lock */ > @@ -1241,10 +1242,11 @@ static void do_ubd_request(struct request_queue *q) > dev->request = req; > dev->start_sg = 0; > dev->end_sg = blk_rq_map_sg(q, req, dev->sg); > + dev->rq_off = 0; > } > > req = dev->request; > - sector = blk_rq_pos(req); > + sector = blk_rq_pos(req) + dev->rq_off; > while(dev->start_sg < dev->end_sg){ > struct scatterlist *sg = &dev->sg[dev->start_sg]; > > @@ -1273,6 +1275,7 @@ static void do_ubd_request(struct request_queue *q) > } > > dev->start_sg++; > + dev->rq_off += sg->length >> 9; > } > dev->end_sg = 0; > dev->request = NULL; > Yes, this works. I quickly tested it on current git version, and it does not require the work-around. So far no corruption seen. Thanks! -Janjaap