Return-Path: linux-nfs-owner@vger.kernel.org Received: from mx12.netapp.com ([216.240.18.77]:34310 "EHLO mx12.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755261Ab3JXPxl convert rfc822-to-8bit (ORCPT ); Thu, 24 Oct 2013 11:53:41 -0400 From: "Myklebust, Trond" To: Jeff Layton CC: Simo Sorce , Christoph Anton Mitterer , "" Subject: Re: XATTRs in NFS? Date: Thu, 24 Oct 2013 15:53:38 +0000 Message-ID: <1382630015.6430.6.camel@leira.trondhjem.org> References: <1382560643.6924.12.camel@heisenberg.scientia.net> <1382624000.6907.8.camel@heisenberg.scientia.net> <1382627225.899.76.camel@willson.li.ssimo.org> <1382627496.6430.2.camel@leira.trondhjem.org> <1382627770.899.79.camel@willson.li.ssimo.org> <20131024112319.7ad9fd27@tlielax.poochiereds.net> In-Reply-To: <20131024112319.7ad9fd27@tlielax.poochiereds.net> Content-Type: text/plain; charset="utf-7" MIME-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Thu, 2013-10-24 at 11:23 -0400, Jeff Layton wrote: +AD4- On Thu, 24 Oct 2013 11:16:10 -0400 +AD4- Simo Sorce +ADw-simo+AEA-redhat.com+AD4- wrote: +AD4- +AD4- +AD4- On Thu, 2013-10-24 at 15:11 +-0000, Myklebust, Trond wrote: +AD4- +AD4- +AD4- On Thu, 2013-10-24 at 11:07 -0400, Simo Sorce wrote: +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- Because the filesystem can do that when multiple applications are +AD4- +AD4- +AD4- +AD4- involved without having to change them all to talk to each other and +AD4- +AD4- +AD4- +AD4- invent custom protocol all the time just to keep some additional +AD4- +AD4- +AD4- +AD4- metadata associated to a file.. +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- +AD4- It's still a custom protocol. The applications need to agree on a data +AD4- +AD4- +AD4- format and store it somewhere. The portable way to do this is to write +AD4- +AD4- +AD4- an application library that they can link to. +AD4- +AD4- +AD4- +AD4- Perhaps I was unclear, you are never going to see that custom library +AD4- +AD4- linked into the 'mv' command. +AD4- +AD4- +AD4- +AD4- So your approach makes little sense if the object is to maintain data +AD4- +AD4- coherent when people need to handle files from random applications and +AD4- +AD4- scripts and general system maintenance. +AD4- +AD4- +AD4- +AD4- The data may be relevant only to a specific application. +AD4- +AD4- +AD4- +AD4- I am not saying you +ACo-have+ACo- to implement xattrs support, just saying that +AD4- +AD4- it is not a mere 'applications should synchronize data themselves' +AD4- +AD4- problem. +AD4- +AD4- +AD4- +AD4- I think the real solution if people need this is to lead an effort to +AD4- put xattrs into the spec. I think there is still time to get new +AD4- features into v4.3 if someone wants to champion it... +AD4- How would that help? Witness Oracle's success with named attributes, which are +AF8-also+AF8- a non-standard filesystem feature that was hastily pushed into the NFSv4 spec. If you really need this for use by applications (as opposed to by sysadmins - see labeled NFS), then get the functionality into POSIX first, then add it to the NFS spec. -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust+AEA-netapp.com www.netapp.com