From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net ([212.227.17.22]:63392 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755294Ab3CaJWy (ORCPT ); Sun, 31 Mar 2013 05:22:54 -0400 Received: from mailout-de.gmx.net ([10.1.76.29]) by mrigmx.server.lan (mrigmx002) with ESMTP (Nemesis) id 0LiZta-1UuTtR1ZfQ-00ckZg for ; Sun, 31 Mar 2013 11:22:53 +0200 Message-ID: <515800BB.50102@gmx.net> Date: Sun, 31 Mar 2013 11:24:11 +0200 From: Arne Jansen MIME-Version: 1.0 To: Wang Shilong CC: "list.btrfs@jan-o-sch.net Schmidt" , "linux-btrfs@vger.kernel.org" Subject: Re: [BUG] btrfs quota References: <1DF9A68C-FBA2-460F-921F-CBF94A06CD6B@gmail.com> In-Reply-To: <1DF9A68C-FBA2-460F-921F-CBF94A06CD6B@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hello Wang, On 03/31/13 03:44, Wang Shilong wrote: > Hello Arne, Jan, > > When i run stresstest with quota enabled, i hit a panic where > btrfs_find_all_roots() is called. Would you please double check it. > On what kernel version do you hit this (git commit id preferred)? Can you send us the message from dmesg? Thanks, arne > stresstest -n 10000 -t 4. > > Maybe there is still race condition when walking backref trees, Jan > would you please check the backref.c .. > btrfs_find_all_roots() is called in btrfs_qgroup_account_ref () to find > all roots that reference a extent. I think this is called because > > we introduce referenced/exclusive concepts. The point is that i think > this concept's disadvantages outweigh the advantages: > <1> > walking backref tree is really time-consuming. > <2> referenced/exclusive makes it really complex when snapshot happens. > <3> quota has a high coupling with other module. > I'd prefer to just keep referenced value, it is not be elegant, but > it helps more. > > Thanks, > Wang > > > > >