Return-Path: Received: from mx2.netapp.com ([216.240.18.37]:3933 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755963Ab1EBWCp convert rfc822-to-8bit (ORCPT ); Mon, 2 May 2011 18:02:45 -0400 Subject: Re: How does NFS handle notify? From: Trond Myklebust To: Stef Bon Cc: "J. Bruce Fields" , linux-nfs@vger.kernel.org In-Reply-To: References: <20110502140750.GA10885@fieldses.org> <1304347155.7830.7.camel@lade.trondhjem.org> <1304356699.7830.26.camel@lade.trondhjem.org> <1304367673.20876.1.camel@lade.trondhjem.org> Content-Type: text/plain; charset="UTF-8" Date: Mon, 02 May 2011 18:02:44 -0400 Message-ID: <1304373764.23069.17.camel@lade.trondhjem.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Mon, 2011-05-02 at 22:28 +0200, Stef Bon wrote: > 2011/5/2 Trond Myklebust : > > >> > >> So, what's your opinion? > > > > Your proposal requires NFS and CIFS protocol support and I just told you > > that there is none in NFS... > > Hi, > > yes I've read that. I also have read that there is possibly support > for in newer versions in NFS. As I said, there is support for dnotify-like functionality in NFSv4.1, but no support for inotify, and certainly not for fanotify. > I imagined that you (not only you but I mean all who are working on > NFS) are interested to find a good way to do this. You've proposed a 'solution', but I'm still not seeing what the problem is. 1. Why do we need to develop kernel support for dnotify+inotify+... in every networked filesystem + fuse? 2. What are the killer app use cases that we need to support and that cannot be supported with existing methods? Notifications on large distributed filesystems are a scalability nightmare (particularly so for inotify), so they need careful justification and need to be limited in scope. Just pulling out a solution from your magic hat isn't sufficient. -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@netapp.com www.netapp.com