From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.fusionio.com ([66.114.96.31]:52438 "EHLO mx2.fusionio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752586Ab2JHNTP (ORCPT ); Mon, 8 Oct 2012 09:19:15 -0400 Date: Mon, 8 Oct 2012 09:19:12 -0400 From: Chris Mason To: Liu Bo CC: Chris Mason , Mitch Harder , "linux-btrfs@vger.kernel.org" , "dave@jikos.cz" Subject: Re: [PATCH 2/2 v3] Btrfs: snapshot-aware defrag Message-ID: <20121008131912.GA4132@shiny> References: <1347875936-14165-1-git-send-email-bo.li.liu@oracle.com> <1347875936-14165-2-git-send-email-bo.li.liu@oracle.com> <50625569.9040102@oracle.com> <20121003140259.GA4458@shiny> <5072C492.8040205@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" In-Reply-To: <5072C492.8040205@oracle.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Mon, Oct 08, 2012 at 06:18:26AM -0600, Liu Bo wrote: > On 10/03/2012 10:02 PM, Chris Mason wrote: > > On Tue, Sep 25, 2012 at 07:07:53PM -0600, Liu Bo wrote: > >> On 09/26/2012 01:39 AM, Mitch Harder wrote: > >>> On Mon, Sep 17, 2012 at 4:58 AM, Liu Bo wrote: > >>>> This comes from one of btrfs's project ideas, > >>>> As we defragment files, we break any sharing from other snapshots. > >>>> The balancing code will preserve the sharing, and defrag needs to grow this > >>>> as well. > >>>> > >>>> Now we're able to fill the blank with this patch, in which we make full use of > >>>> backref walking stuff. > >>>> > >>>> Here is the basic idea, > >>>> o set the writeback ranges started by defragment with flag EXTENT_DEFRAG > >>>> o at endio, after we finish updating fs tree, we use backref walking to find > >>>> all parents of the ranges and re-link them with the new COWed file layout by > >>>> adding corresponding backrefs. > >>>> > >>>> Originally patch by Li Zefan > >>>> Signed-off-by: Liu Bo > >>> > >>> I'm hitting the WARN_ON in record_extent_backrefs() indicating a > >>> problem with the return value from iterate_inodes_from_logical(). > > > > Me too. It triggers reliably with mount -o autodefrag, and then crashes > > a in the next function ;) > > > > -chris > > > > Hi Chris, Mitch, > > I'm afraid that I may need a little more time to fix all bugs in it because there seems to be > some backref walking bugs mixed in, and at least 4 different crashes make it harder to address bugs. > > I use an 1G random write fio job running in background, following by creating 20 snapshots in background, > and mount -o autodefrag. > > So if your crash is quite stable in one place, please let me know the steps. I have a notmuch mail database. I just receive mail with auto defrag on and it crashes. Chrome databases may do it as well. If it helps, I have compression too. -chris