From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Chinner Subject: Re: [PATCH 3/4] fs: Remove i_size check from do_fallocate Date: Mon, 14 Apr 2014 09:39:58 +1000 Message-ID: <20140413233958.GB27694@dastard> References: <1397242665-2183-1-git-send-email-lczerner@redhat.com> <1397242665-2183-3-git-send-email-lczerner@redhat.com> <20140412135906.GC13837@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Lukas Czerner , linux-fsdevel@vger.kernel.org, ceph-devel@vger.kernel.org, linux-ext4@vger.kernel.org, xfs@oss.sgi.com To: Theodore Ts'o Return-path: Received: from ipmail06.adl6.internode.on.net ([150.101.137.145]:61892 "EHLO ipmail06.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750757AbaDMXkD (ORCPT ); Sun, 13 Apr 2014 19:40:03 -0400 Content-Disposition: inline In-Reply-To: <20140412135906.GC13837@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sat, Apr 12, 2014 at 09:59:06AM -0400, Theodore Ts'o wrote: > On Fri, Apr 11, 2014 at 08:57:44PM +0200, Lukas Czerner wrote: > > Currently in do_fallocate in collapse range case we're checking whether > > offset + len is not bigger than i_size. However there is nothing which > > would prevent i_size from changing so the check is pointless. It should > > be done in the file system itself and the file system needs to make sure > > that i_size is not going to change. > > > > As it is now we can easily crash kernel by having two processes doing > > truncate and fallocate collapse range at the same time. This can be > > reproduced on ext4 and it is theoretically possible on xfs even though I > > was not able to trigger it with this simple test. > > > > This commit removes the check from do_fallocate and adds it to the file > > system. > > > > Signed-off-by: Lukas Czerner > > --- > > fs/ext4/extents.c | 11 +++++++++-- > > fs/open.c | 8 -------- > > fs/xfs/xfs_file.c | 10 +++++++++- > > 3 files changed, 18 insertions(+), 11 deletions(-) > > Looks good to me. Do the xfs folks mind if I carry this in the ext4 > tree and push it to Linus shortly after -rc1? If so, please send me > an ack'ed by. No, go ahead. I was going to do the same thing, anyway, if nobody else beat me to it... Acked-by: Dave Chinner Cheers, Dave -- Dave Chinner david@fromorbit.com