From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932611Ab2EVUcy (ORCPT ); Tue, 22 May 2012 16:32:54 -0400 Received: from mx2.netapp.com ([216.240.18.37]:38955 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755921Ab2EVUcw (ORCPT ); Tue, 22 May 2012 16:32:52 -0400 X-IronPort-AV: E=Sophos;i="4.75,640,1330934400"; d="scan'208";a="649546604" From: "Myklebust, Trond" To: Stanislav Kinsbursky CC: "linux-nfs@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "devel@openvz.org" Subject: Re: [PATCH] NFS: init client before declaration Thread-Topic: [PATCH] NFS: init client before declaration Thread-Index: AQHNOBgchN+45TnxmEuX3jdeWgHLc5bWU9EAgAAIiACAAAgtgIAABjUAgAAHbgCAAAb8AIAAQCGA Date: Tue, 22 May 2012 20:32:51 +0000 Message-ID: <1337718771.4269.29.camel@lade.trondhjem.org> References: <20120522124018.338.20817.stgit@localhost.localdomain> <1337696984.4269.4.camel@lade.trondhjem.org> <1337698816.4269.15.camel@lade.trondhjem.org> <4FBBB0DB.6050708@parallels.com> <1337701904.4269.16.camel@lade.trondhjem.org> <4FBBBC4C.5010103@parallels.com> <1337705000.4269.23.camel@lade.trondhjem.org> In-Reply-To: <1337705000.4269.23.camel@lade.trondhjem.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.104.60.115] Content-Type: text/plain; charset="utf-8" Content-ID: <6E62AFCB2BB9D643B62F15DC0E480065@tahoe.netapp.com> MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by nfs id q4MKX2jE019768 On Tue, 2012-05-22 at 12:43 -0400, Trond Myklebust wrote: > On Tue, 2012-05-22 at 20:18 +0400, Stanislav Kinsbursky wrote: > > We have another problem here. > > nfs4_init_client() will try to create pipe dentries prior to set of NFS_CS_READY > > to the client. And dentries will be created since semaphore is dropped and > > per-net superblock variable is initialized already. > > But __rpc_pipefs_event() relays on the fact, that no dentries present. > > Looks like the problem was introduced by me in aad9487c... > > So maybe we should not call "continue" instead "__rpc_pipefs_event()", when > > client becomes ready? > > Looks like this will allow us to handle such races. > > Let me rework this patch a bit... The following is ugly, but it should be demonstrably correct, and will ensure that __rpc_pipefs_event() will only be called for fully initialised nfs_clients... 8<--------------------------------------------------------------------- >>From 90c3b9fe9faeae32c8f629e8b6cbf5f50bb9b295 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Tue, 22 May 2012 16:22:50 -0400 Subject: [PATCH 1/2] NFSv4: Fix a race in the net namespace mount notification Since the struct nfs_client gets added to the global nfs_client_list before it is initialised, it is possible that rpc_pipefs_event can end up trying to create idmapper entries on such a thing. The solution is to have the mount notification wait for the initialisation of each nfs_client to complete, and then to skip any entries for which the it failed. Reported-by: Stanislav Kinsbursky Signed-off-by: Trond Myklebust --- fs/nfs/client.c | 10 ++++++++++ fs/nfs/idmap.c | 15 +++++++++++++++ fs/nfs/internal.h | 1 + 3 files changed, 26 insertions(+), 0 deletions(-) diff --git a/fs/nfs/client.c b/fs/nfs/client.c index 60f7e4e..d3c8553 100644 --- a/fs/nfs/client.c +++ b/fs/nfs/client.c @@ -583,6 +583,16 @@ found_client: return clp; } +static bool nfs_client_ready(const struct nfs_client *clp) +{ + return clp->cl_cons_state <= NFS_CS_READY; +} + +int nfs_wait_client_ready(const struct nfs_client *clp) +{ + return wait_event_killable(nfs_client_active_wq, nfs_client_ready(clp)); +} + /* * Mark a server as ready or failed */ diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c index 3e8edbe..c0753c5 100644 --- a/fs/nfs/idmap.c +++ b/fs/nfs/idmap.c @@ -530,9 +530,24 @@ static struct nfs_client *nfs_get_client_for_event(struct net *net, int event) struct nfs_net *nn = net_generic(net, nfs_net_id); struct dentry *cl_dentry; struct nfs_client *clp; + int err; +restart: spin_lock(&nn->nfs_client_lock); list_for_each_entry(clp, &nn->nfs_client_list, cl_share_link) { + /* Wait for initialisation to finish */ + if (clp->cl_cons_state > NFS_CS_READY) { + atomic_inc(&clp->cl_count); + spin_unlock(&nn->nfs_client_lock); + err = nfs_wait_client_ready(clp); + nfs_put_client(clp); + if (err) + return NULL; + goto restart; + } + /* Skip nfs_clients that failed to initialise */ + if (clp->cl_cons_state < 0) + continue; if (clp->rpc_ops != &nfs_v4_clientops) continue; cl_dentry = clp->cl_idmap->idmap_pipe->dentry; diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h index b777bda..3ee4040 100644 --- a/fs/nfs/internal.h +++ b/fs/nfs/internal.h @@ -168,6 +168,7 @@ extern struct nfs_server *nfs_clone_server(struct nfs_server *, struct nfs_fattr *, rpc_authflavor_t); extern void nfs_mark_client_ready(struct nfs_client *clp, int state); +extern int nfs_wait_client_ready(const struct nfs_client *clp); extern int nfs4_check_client_ready(struct nfs_client *clp); extern struct nfs_client *nfs4_set_ds_client(struct nfs_client* mds_clp, const struct sockaddr *ds_addr, -- 1.7.7.6 -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@netapp.com www.netapp.com {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I