Return-Path: Received: from shutemov.name ([188.40.19.243]:43024 "EHLO shutemov.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755056Ab1ATLfx (ORCPT ); Thu, 20 Jan 2011 06:35:53 -0500 Date: Thu, 20 Jan 2011 13:35:52 +0200 From: "Kirill A. Shutemov" To: Rob Landley Cc: "Kirill A. Shutemov" , Trond Myklebust , "J. Bruce Fields" , Neil Brown , Pavel Emelyanov , linux-nfs@vger.kernel.org, "David S. Miller" , Al Viro , containers@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 00/16] make rpc_pipefs be mountable multiple time Message-ID: <20110120113552.GB24349@shutemov.name> References: <1295012954-7769-1-git-send-email-kas@openvz.org> <4D343658.1020205@parallels.com> Content-Type: text/plain; charset=us-ascii In-Reply-To: <4D343658.1020205@parallels.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Mon, Jan 17, 2011 at 06:30:16AM -0600, Rob Landley wrote: > On 01/14/2011 07:48 AM, Kirill A. Shutemov wrote: > > Prepare nfs/sunrpc stack to use multiple instances of rpc_pipefs. > > Only for client for now. > > Ok, Google is being really unhelpful here. It's better if you read the code. :) > > What is rpc_pipefs for? What uses it, and to do what exactly? Is it > used by nfs server code, or by the client code, or both? Is it a way > for userspace to talk to the kernel, or for the kernel to talk to > itself? Is it used at mount time, or during filesystem operation? Ok, It try to answer. Please correct me, if I'm wrong. rpc_pipefs is a userland/kernel interface (I don't see kernel-kernel usecases, but it's possible, I guess). There is client dir (nfs/clntX) in rpc_pipefs for every sunrpc client. Both client and server (see fs/nfsd/nfs4callback.c) can create sunrpc client. So we rpc_pipefs on both side. rpc_pipefs uses not only on mount time. See old idmapper, for example. > I'm interested in giving this patch series a much more thorough review, > but I can't figure out what the subsystem it's modifying actually _is_. > > (Maybe this is something to do with filesystems/nfs/rpc-cache.txt?) > > Rob -- Kirill A. Shutemov