From: =?ISO-8859-15?Q?Luk=E1=A8_Czerner?= Subject: Re: [PATCH v4 15/20] ext4: use ext4_zero_partial_blocks in punch_hole Date: Thu, 20 Jun 2013 11:12:02 +0200 (CEST) Message-ID: References: <1368549454-8930-1-git-send-email-lczerner@redhat.com> <1368549454-8930-16-git-send-email-lczerner@redhat.com> <20130614030154.GA18731@thunk.org> <20130619234243.GE24587@thunk.org> Mime-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="8323328-1096263112-1371719525=:1929" Cc: linux-ext4@vger.kernel.org, Ashish Sangwan To: "Theodore Ts'o" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:45868 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935296Ab3FTJMI (ORCPT ); Thu, 20 Jun 2013 05:12:08 -0400 In-Reply-To: <20130619234243.GE24587@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323328-1096263112-1371719525=:1929 Content-Type: TEXT/PLAIN; charset=utf-8 Content-Transfer-Encoding: 8BIT On Wed, 19 Jun 2013, Theodore Ts'o wrote: > Date: Wed, 19 Jun 2013 19:42:43 -0400 > From: Theodore Ts'o > To: Lukáš Czerner > Cc: linux-ext4@vger.kernel.org, Ashish Sangwan > Subject: Re: [PATCH v4 15/20] ext4: use ext4_zero_partial_blocks in punch_hole > > On Wed, Jun 19, 2013 at 06:37:53PM +0200, Lukáš Czerner wrote: > > > > I think I've got this. The problem actually is in > > ext4_zero_partial_blocks() where we would attempt to zero out page > > which has been previously released by truncate_pagecache_range(). > > This might happen when we're punching out just a single page because > > in ext4_zero_partial_blocks() we do not check whether we're dealing > > with the whole, or partial page. At the point we're going to zero it > > out it might have been already released and reused by someone else. > > > > This patch should fix this issue. And indeed with this applied I do > > not see the problem anymore but I am still testing. > > Thanks for finding this! I'm still doing testing of your trial patch > myself, but initial results seem to indicate that this also solves the > failures 269 and 270 which was apparently uncovered by Ashish's patch > "ext4: optimize extent selection for block removal in case of hole > punch". > > - Ted Hi Ted, from my testing I still see problems with test 269, however I've seen this even without the patch #15 so I am not sure that it's caused by this. I'll send a proper patch soon. Thanks! -Lukas --8323328-1096263112-1371719525=:1929--