From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dominique Martinet Subject: Re: [V9fs-developer] [RFC][PATCH] ovl: count subdirs to get the correct link count Date: Mon, 12 Oct 2015 18:15:28 +0200 Message-ID: <20151012161528.GA22376@nautica> References: <1444636874-16886-1-git-send-email-wenqing.lz@taobao.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Received: from nautica.notk.org ([91.121.71.147]:60893 "EHLO nautica.notk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752546AbbJLQPo (ORCPT ); Mon, 12 Oct 2015 12:15:44 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-unionfs-owner@vger.kernel.org List-Id: linux-unionfs@vger.kernel.org To: Miklos Szeredi Cc: Zheng Liu , v9fs-developer@lists.sourceforge.net, "linux-unionfs@vger.kernel.org" , Zheng Liu Miklos Szeredi wrote on Mon, Oct 12, 2015: > On Mon, Oct 12, 2015 at 10:01 AM, Zheng Liu wrote: > > This warning can be reproduced by the following steps. > > > > [In host os] > > 1. build a ROOTFS for booting up a vm using 9pfs > > 2. mount -t overlay -olowerdir=${lower},upperdir=${upper},workdir={work} none ${ROOTFS}/mnt > > 3. run a vm using 9pfs > > e.g. http://www.linux-kvm.org/page/9p_virtio > > [In guest os] > > 4. cd /mnt > > 5. mkdir 1 > > 6. rm -rf 1; mkdir 1 > > In the stack trace above I don'[t see overlayfs calls. So apparently > the mkdir goes directly to the 9p filesystem. So where's overlayfs in > all this? It's probably as he described: host os overlayfs mount exported by qemu as a 9P mount to a guest linux The warning is on the client (where 9P is mounted), basically complaining that the server, so qemu, is lying -- and it is because overlayfs apparently does. You won't see any new crash/warn with 9p and overlayfs mixed in because that broke in 4.2 (4bacc9 "overlayfs: Make f_path always point to the overlay and f_inode to the underlay"), and I never got any reply when asking how 9P could "pick" its inode/file struct. Maybe that's not possible and I should look for another way of fixing this, but I haven't had much time and no-one seems to care... Anyway, I don't mean to hijack this thread, sorry for disgressing. -- Dominique Martinet