From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1755035Ab1K2Rau (ORCPT <rfc822;w@1wt.eu>);
	Tue, 29 Nov 2011 12:30:50 -0500
Received: from mail-vx0-f174.google.com ([209.85.220.174]:53690 "EHLO
	mail-vx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1753457Ab1K2Rat (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Tue, 29 Nov 2011 12:30:49 -0500
MIME-Version: 1.0
In-Reply-To: <1322587165.4174.20.camel@lade.trondhjem.org>
References: <20111129090754.20730.64567.stgit@localhost6.localdomain6>
 <20111129091037.20730.59391.stgit@localhost6.localdomain6>
 <F19688880B763E40B28B2B462677FBF805E3A4AFF2@MX09A.corp.emc.com>
 <4ED4CDCE.9080804@parallels.com> <F19688880B763E40B28B2B462677FBF805E3A4AFFD@MX09A.corp.emc.com>
 <2E1EB2CF9ED1CB4AA966F0EB76EAB4430C3CBC23@SACMVEXC2-PRD.hq.netapp.com>
 <CA+a=Yy5GKMu8rbh8y3fOtK6pmqygPNBr=a+p7LfcmTqtXFH3iA@mail.gmail.com>
 <1322579906.3619.1.camel@lade.trondhjem.org> <CA+a=Yy6kJe0NemSiRwM+t8gz5-UF5fOdwdS2so+q=nSYjBx--w@mail.gmail.com>
 <1322584830.4174.16.camel@lade.trondhjem.org> <20111129164252.GA19528@fieldses.org>
 <1322587165.4174.20.camel@lade.trondhjem.org>
From: Peng Tao <bergwolf@gmail.com>
Date: Wed, 30 Nov 2011 01:30:27 +0800
Message-ID: <CA+a=Yy4bEKaeUihjYLRzXVbjA3fc2EuZ3ToAkf0w-oL3PnZJKQ@mail.gmail.com>
Subject: Re: [PATCH 4/5] NFS: remove RPC PipeFS mount point reference from
 blocklayout routines
To: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>, tao.peng@emc.com,
        skinsbursky@parallels.com, linux-nfs@vger.kernel.org,
        xemul@parallels.com, neilb@suse.de, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, jbottomley@parallels.com,
        davem@davemloft.net, devel@openvz.org
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, Nov 30, 2011 at 1:19 AM, Trond Myklebust
<Trond.Myklebust@netapp.com> wrote:
> On Tue, 2011-11-29 at 11:42 -0500, J. Bruce Fields wrote:
>> On Tue, Nov 29, 2011 at 11:40:30AM -0500, Trond Myklebust wrote:
>> > I mean that I'm perfectly entitled to do
>> >
>> > 'modprobe -r blocklayoutdriver'
>> >
>> > and when I do that, then I expect blkmapd to close the rpc pipe and wait
>> > for a new one to be created just like rpc.idmapd and rpc.gssd do when I
>> > remove the nfs and sunrpc modules.
>>
>> The rpc pipefs mount doesn't hold a reference on the sunrpc module?
>
> I stand corrected: the mount does hold a reference to the sunrpc
> module.
> However nothing holds a reference to the blocklayoutdriver module, so
> the main point that the "blocklayout" pipe can disappear from underneath
> the blkmapd stands.
Thanks for the explanation and I agree it can cause problem if user
reload blocklayout module. I will look into a fix to blkmapd.

Best,
Tao