From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mo-p00-ob.rzone.de ([81.169.146.160]:21647 "EHLO mo-p00-ob.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753657Ab3FGOkr (ORCPT ); Fri, 7 Jun 2013 10:40:47 -0400 Message-ID: <51B1F130.90401@giantdisaster.de> Date: Fri, 07 Jun 2013 16:41:52 +0200 From: Stefan Behrens MIME-Version: 1.0 To: Josef Bacik CC: "linux-btrfs@vger.kernel.org" Subject: Re: [PATCH v4 6/8] Btrfs: introduce uuid-tree-gen field References: <49cfd0aca92177345f59f3f700f6d43f8445f405.1370534938.git.sbehrens@giantdisaster.de> <20130607143916.GE29248@localhost.localdomain> In-Reply-To: <20130607143916.GE29248@localhost.localdomain> Content-Type: text/plain; charset=UTF-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 06/07/2013 16:39, Josef Bacik wrote: > On Fri, Jun 07, 2013 at 04:27:51AM -0600, Stefan Behrens wrote: >> In order to be able to detect the case that a filesystem is mounted >> with an old kernel, add a uuid-tree-gen field like the free space >> cache is doing it. It is part of the super block and written with >> each commit. Old kernels do not know this field and don't update it. >> > > So to get around the whole crashing before we finish creating the uuid tree > maybe set some flag or something that doesn't actually set the > super->uuid_tree_generation until _after_ it finishes populating the tree, and > then have the scan deal with having a half populated tree. Just an idea, but we > have to deal with it some way. Thanks, That's what the patch 7/8 is doing.