From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:15292 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754868Ab0JLTwJ (ORCPT ); Tue, 12 Oct 2010 15:52:09 -0400 Date: Tue, 12 Oct 2010 15:52:34 -0400 From: Jeff Layton To: Trond Myklebust Cc: Chuck Lever , Linux NFS Mailing List Subject: Re: whither NFS umount? Message-ID: <20101012155234.094a87c3@corrin.poochiereds.net> In-Reply-To: <1286912649.1956.19.camel@heimdal.trondhjem.org> References: <678C897C-DECE-49C1-AFC4-B57CF3A09385@oracle.com> <1286903046.24878.13.camel@heimdal.trondhjem.org> <20101012151826.76b75f52@corrin.poochiereds.net> <1286912649.1956.19.camel@heimdal.trondhjem.org> Content-Type: text/plain; charset=US-ASCII Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Tue, 12 Oct 2010 15:44:09 -0400 Trond Myklebust wrote: > On Tue, 2010-10-12 at 15:18 -0400, Jeff Layton wrote: > > > I think the part that causes problems is having userspace do this. In > > theory, if the kernel were in charge of sending the UMNT, then it's not > > really a problem since it knows when to do it. If we have code that > > sends a UMNT already, why not do a best-effort UMNT call from the > > kernel when we tear down the sb? > > Purely for the pleasure of allowing the server to maintain inaccurate > statistics about who is currently mounting what? I think not... > > You can get far more accurate results by replacing the MNT/UMNT state > counter with a purely server-based scheme to track who accessed one or > more files on each exported partition in the past 5 minutes or so. That > would even work with NFSv4... > True, but for better or worse, UMNT is part of the protocol. It seems like we ought to do our best to implement it, even if it is fundamentally flawed. -- Jeff Layton