From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: linux-nfs-owner@vger.kernel.org Received: from relay.parallels.com ([195.214.232.42]:53280 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752932Ab2IJIn6 convert rfc822-to-8bit (ORCPT ); Mon, 10 Sep 2012 04:43:58 -0400 Message-ID: <504DA833.60301@parallels.com> Date: Mon, 10 Sep 2012 12:43:31 +0400 From: Stanislav Kinsbursky MIME-Version: 1.0 To: "Myklebust, Trond" CC: Jeff Layton , "bfields@fieldses.org" , "linux-nfs@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "devel@openvz.org" Subject: Re: [PATCH v2] SUNRPC: check current nsproxy before set of node name on client creation References: <20120813113731.9629.31906.stgit@localhost.localdomain> <20120813081054.0ee39037@corrin.poochiereds.net> <4FA345DA4F4AE44899BD2B03EEEC2FA908F90888@SACEXCMBX04-PRD.hq.netapp.com> <504ADED9.2020607@parallels.com> <4FA345DA4F4AE44899BD2B03EEEC2FA908F914D4@SACEXCMBX04-PRD.hq.netapp.com> In-Reply-To: <4FA345DA4F4AE44899BD2B03EEEC2FA908F914D4@SACEXCMBX04-PRD.hq.netapp.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Sender: linux-nfs-owner@vger.kernel.org List-ID: 08.09.2012 18:33, Myklebust, Trond пишет: > On Sat, 2012-09-08 at 08:59 +0300, Stanislav Kinsbursky wrote: >> 08.09.2012 01:32, Myklebust, Trond пишет: >>> On Mon, 2012-08-13 at 08:10 -0400, Jeff Layton wrote: >>>> On Mon, 13 Aug 2012 15:37:31 +0400 >>>> Stanislav Kinsbursky wrote: >>>> >>>>> v2: >>>>> 1) rpc_clnt_set_nodename() prototype updated. >>>>> 2) fixed errors in comment. >>>>> >>>>> When child reaper exits, it can destroy mount namespace it belongs to, and if >>>>> there are NFS mounts inside, then it will try to umount them. But in this >>>>> point current->nsproxy is set to NULL and all namespaces will be destroyed one >>>>> by one. I.e. we can't dereference current->nsproxy to obtain uts namespace. >>>>> >>>>> Signed-off-by: Stanislav Kinsbursky >>>>> --- >>>>> net/sunrpc/clnt.c | 16 +++++++++++++--- >>>>> 1 files changed, 13 insertions(+), 3 deletions(-) >>>>> >>>>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c >>>>> index 9a9676e..8fbcbc8 100644 >>>>> --- a/net/sunrpc/clnt.c >>>>> +++ b/net/sunrpc/clnt.c >>>>> @@ -277,8 +277,18 @@ void rpc_clients_notifier_unregister(void) >>>>> return rpc_pipefs_notifier_unregister(&rpc_clients_block); >>>>> } >>>>> >>>>> -static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename) >>>>> +static void rpc_clnt_set_nodename(struct rpc_clnt *clnt) >>>>> { >>>>> + const char *nodename; >>>>> + >>>>> + /* >>>>> + * We have to protect against dying child reaper, which has released >>>>> + * its nsproxy already and is trying to destroy mount namespace. >>>>> + */ >>>>> + if (current->nsproxy == NULL) >>>>> + return; >>>>> + >>>>> + nodename = utsname()->nodename; >>>>> clnt->cl_nodelen = strlen(nodename); >>>>> if (clnt->cl_nodelen > UNX_MAXNODENAME) >>>>> clnt->cl_nodelen = UNX_MAXNODENAME; >>>>> @@ -365,7 +375,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru >>>>> } >>>>> >>>>> /* save the nodename */ >>>>> - rpc_clnt_set_nodename(clnt, utsname()->nodename); >>>>> + rpc_clnt_set_nodename(clnt); >>>>> rpc_register_client(clnt); >>>>> return clnt; >>>>> >>>>> @@ -524,7 +534,7 @@ rpc_clone_client(struct rpc_clnt *clnt) >>>>> err = rpc_setup_pipedir(new, clnt->cl_program->pipe_dir_name); >>>>> if (err != 0) >>>>> goto out_no_path; >>>>> - rpc_clnt_set_nodename(new, utsname()->nodename); >>>>> + rpc_clnt_set_nodename(new); >>>>> if (new->cl_auth) >>>>> atomic_inc(&new->cl_auth->au_count); >>>>> atomic_inc(&clnt->cl_count); >>>>> >>>>> -- >>>>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >>>>> the body of a message to majordomo@vger.kernel.org >>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> Acked-by: Jeff Layton >>> OK, colour me confused (again). >> >> What color? >> >>> Why should a umount trigger an >>> rpc_create() or rpc_clone_client()? >> >> It calls nsm_create(). >> Here is the trace (https://bugzilla.redhat.com/show_bug.cgi?id=830862, >> comment 68): > > Right, but if we're using NFSv3 lock monitoring, we know in advance that > we're going to need an nsm call to localhost. Why can't we just cache > the one that we used to start lock monitoring in the first place? > Do you suggest to cache the call or the client for the call? -- Best regards, Stanislav Kinsbursky