From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261793AbUEFGrk (ORCPT ); Thu, 6 May 2004 02:47:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261764AbUEFGq1 (ORCPT ); Thu, 6 May 2004 02:46:27 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:48586 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S261791AbUEFGqR (ORCPT ); Thu, 6 May 2004 02:46:17 -0400 Date: Thu, 6 May 2004 07:46:17 +0100 From: viro@parcelfarce.linux.theplanet.co.uk To: Tim Hockin Cc: linux-kernel@vger.kernel.org Subject: Re: lazy-umount cwd and .. Message-ID: <20040506064617.GQ17014@parcelfarce.linux.theplanet.co.uk> References: <20040506044433.GA13933@hockin.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040506044433.GA13933@hockin.org> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 05, 2004 at 09:44:33PM -0700, Tim Hockin wrote: > I notice that a process that is in a dir which gets lazy-unmounted > suddenly sees it's current dir change and its '..' dir points back to > itself. > > I'm not sure it's a huge deal, but we have a half-patch floating around > that changes the behavior such that the unmounted mnt->mnt_parent is > retained and unreferenced when the mnt is finally released. This seems to > make any process which is in the unmounted mount not see anything > different, but does not let any new processes into the mount. > > Minor, but friendly. > > Should I bother to polish this patch off and send it, or is it just not > something we want to care about? No. This is simply wrong - one of the situations when you want lazy-umount is getting a stuck filesystem (e.g. NFS mounted hard) and wanting to get it out of the way, so that stuff it's mounted on could be unmounted clean. So we definitely don't want to keep anything pinned down.