From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752218Ab0GAEWv (ORCPT ); Thu, 1 Jul 2010 00:22:51 -0400 Received: from sh.osrg.net ([192.16.179.4]:40259 "EHLO sh.osrg.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750718Ab0GAEWt (ORCPT ); Thu, 1 Jul 2010 00:22:49 -0400 Date: Thu, 1 Jul 2010 13:21:42 +0900 To: hch@lst.de Cc: snitzer@redhat.com, axboe@kernel.dk, dm-devel@redhat.com, James.Bottomley@suse.de, linux-kernel@vger.kernel.org, martin.petersen@oracle.com, akpm@linux-foundation.org, linux-scsi@vger.kernel.org Subject: Re: [PATCH 1/2] block: fix leaks associated with discard request payload From: FUJITA Tomonori In-Reply-To: <20100630205458C.fujita.tomonori@lab.ntt.co.jp> References: <20100628171218Q.fujita.tomonori@lab.ntt.co.jp> <20100628152536.GA16013@lst.de> <20100630205458C.fujita.tomonori@lab.ntt.co.jp> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-Id: <20100701132130F.fujita.tomonori@lab.ntt.co.jp> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-3.0 (sh.osrg.net [192.16.179.4]); Thu, 01 Jul 2010 13:21:44 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 30 Jun 2010 20:55:09 +0900 FUJITA Tomonori wrote: > On Mon, 28 Jun 2010 17:25:36 +0200 > Christoph Hellwig wrote: > > > On Mon, Jun 28, 2010 at 05:14:28PM +0900, FUJITA Tomonori wrote: > > > > While I see the problems with leaking ressources in that case I still > > > > can't quite explain the hang I see. > > > > > > Any way to reproduce the hang without ssd drives? > > > > Actually the SSDs don't fully hang, they just causes lots of I/O errors > > and hit the error handler hard. The hard hang is when running under > > qemu. Apply the patch below, then create an if=scsi drive that resides > > on an XFS filesystem, and you'll have scsi TP support in the guest: > > Ok, I figured out what's wrong. > > As I suspected, it's due to the partial completion. > > qemu scsi driver tells that the WRITE_SAME command was successful but > somehow the command has resid. So we retry it again and again (and > leak some memory). > > I don't know yet why qemu scsi driver is broken. Maybe there is a bug > in it or converting discard to FS sends broken commands to the driver. looks like your qemu WRITE_SAME patch isn't completed :) You implement WRITE_SAME as if it doesn't do any data transfer. So qemu scsi driver gets resid. The reason why WRITE_SAME works now is that scsi-ml doesn't care about resid with PC commands but it cares with FS commands. I confirmed that qemu scsi driver gets the identical command with both PC and FS commands and qemu calls xfsctl. > I've put a patch to complete discard command in the all-or-nothing > manner: > > git://git.kernel.org/pub/scm/linux/kernel/git/tomo/linux-2.6-misc.git discard Seems that I finished discard FS conversion. I'll update it on the top of James' uprep patchset soon.