From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BBE42C433E0 for ; Wed, 8 Jul 2020 14:27:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 92C01206DF for ; Wed, 8 Jul 2020 14:27:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="G3hM8ayu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729526AbgGHO1C (ORCPT ); Wed, 8 Jul 2020 10:27:02 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:43122 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729468AbgGHO1C (ORCPT ); Wed, 8 Jul 2020 10:27:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594218420; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KOVfaOphciy8vbgJGYYej3cFPI5a0So+QJK6ub8tUBM=; b=G3hM8ayuGJmBDdmdq4iPO2tUnPb0tbC1CDygZOX+jCa/s93PJlizCZVdQnNcQFGWCd6X2H T4s0kVyvQ9yeVPiKSrXFYTNb3m/36MpeyU8/t2nmFF20Y93y03jlNWa5wCi5OZbu5oGpyI HtyI78AGnvTN0W24EIN2SfChjRHQsxk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-82-9rIrnC-zOk-hEs5L0-RzYg-1; Wed, 08 Jul 2020 10:26:55 -0400 X-MC-Unique: 9rIrnC-zOk-hEs5L0-RzYg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4C3661005504; Wed, 8 Jul 2020 14:26:54 +0000 (UTC) Received: from horse.redhat.com (ovpn-115-128.rdu2.redhat.com [10.10.115.128]) by smtp.corp.redhat.com (Postfix) with ESMTP id 036AC5C1B2; Wed, 8 Jul 2020 14:26:54 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id 8DF08223B92; Wed, 8 Jul 2020 10:26:53 -0400 (EDT) Date: Wed, 8 Jul 2020 10:26:53 -0400 From: Vivek Goyal To: Amir Goldstein Cc: Miklos Szeredi , overlayfs , Fabian Subject: Re: overlayfs: issue with a replaced lower squashfs with export-table Message-ID: <20200708142653.GB103536@redhat.com> References: <20200707155159.GA48341@redhat.com> <20200707215309.GB48341@redhat.com> <20200708142353.GA103536@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200708142353.GA103536@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-unionfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org On Wed, Jul 08, 2020 at 10:23:53AM -0400, Vivek Goyal wrote: > On Wed, Jul 08, 2020 at 11:50:29AM +0300, Amir Goldstein wrote: > > On Wed, Jul 8, 2020 at 11:37 AM Miklos Szeredi wrote: > > > > > > On Wed, Jul 8, 2020 at 10:31 AM Amir Goldstein wrote: > > > > > > > > > > > 1) is not problematic IMO and the simple patch I posted may be applied > > > > for fixing the reported issue, but it only solved the special case of null uuid. > > > > The problem still exists with re-creating lower on xfs/ext4, e.g. by > > > > rm -rf and unpacking image tar. > > > > > > How so? st_ino may be reused but the fh is guaranteed to be unique. > > > > > > > Doh! You are right. I was talking nonsense. > > The only problem would be with re-creating an xfs/ext4 lower image > > with the same uuid maybe because a basic image is cloned. > > > > In any case, it's a corner of a corner of a corner. > > I will post the patch to fix null uuid. > > It will also be good if we can bring some clarity to the documentation > for future references in section "Sharing and copying layers". > > So if IIUC, > > - sharing layers should work with all features of overlayfs. > > - copying layers works only if index and nfs_export is not enabled. Even > if index is not enabled, copying layers will change inode number > reporting behavior (as origin verification will fail). We probably > say something about this. > > - Modifying/recreating lower layer only works when > metacopy/index/nfs_export are not enabled at any point of time. This > also will change inode number reporting behavior. Well, this is not entirely true. redirect might be broken if lower layers have been modified/recreated and that will have issues with directories. /me is again wondering what's the use case of modifying lower layer with an existing upper. Is it fair to say, no don't recreate/modify lower layers and use with existing upper. Thanks Vivek