Return-Path: linux-nfs-owner@vger.kernel.org Received: from mailhub.sw.ru ([195.214.232.25]:30876 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754355Ab3FKOja (ORCPT ); Tue, 11 Jun 2013 10:39:30 -0400 Subject: [PATCH v2 2/4] SUNRPC: fix races on PipeFS MOUNT notifications To: Trond.Myklebust@netapp.com From: Stanislav Kinsbursky Cc: linux-nfs@vger.kernel.org, devel@openvz.org, linux-kernel@vger.kernel.org, jlayton@redhat.com Date: Tue, 11 Jun 2013 18:39:18 +0400 Message-ID: <20130611143917.16046.15791.stgit@localhost.localdomain> In-Reply-To: <20130611143725.16046.17279.stgit@localhost.localdomain> References: <20130611143725.16046.17279.stgit@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: Below are races, when RPC client can be created without PiepFS dentries CPU#0 CPU#1 ----------------------------- ----------------------------- rpc_new_client rpc_fill_super rpc_setup_pipedir mutex_lock(&sn->pipefs_sb_lock) rpc_get_sb_net == NULL (no per-net PipeFS superblock) sn->pipefs_sb = sb; notifier_call_chain(MOUNT) (client is not in the list) rpc_register_client (client without pipes dentries) To fix this patch: 1) makes PipeFS mount notification call with pipefs_sb_lock being held. 2) releases pipefs_sb_lock on new SUNRPC client creation only after registration. Signed-off-by: Stanislav Kinsbursky Cc: stable@vger.kernel.org --- net/sunrpc/clnt.c | 24 +++++++++++++----------- net/sunrpc/rpc_pipe.c | 3 +++ 2 files changed, 16 insertions(+), 11 deletions(-) diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 4bf2409..48888ee 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -157,20 +157,15 @@ static struct dentry *rpc_setup_pipedir_sb(struct super_block *sb, } static int -rpc_setup_pipedir(struct rpc_clnt *clnt, const char *dir_name) +rpc_setup_pipedir(struct rpc_clnt *clnt, const char *dir_name, + struct super_block *pipefs_sb) { - struct net *net = rpc_net_ns(clnt); - struct super_block *pipefs_sb; struct dentry *dentry; clnt->cl_dentry = NULL; if (dir_name == NULL) return 0; - pipefs_sb = rpc_get_sb_net(net); - if (!pipefs_sb) - return 0; dentry = rpc_setup_pipedir_sb(pipefs_sb, clnt, dir_name); - rpc_put_sb_net(net); if (IS_ERR(dentry)) return PTR_ERR(dentry); clnt->cl_dentry = dentry; @@ -294,11 +289,16 @@ static int rpc_client_register(const struct rpc_create_args *args, { const struct rpc_program *program = args->program; struct rpc_auth *auth; + struct net *net = rpc_net_ns(clnt); + struct super_block *pipefs_sb; int err = 0; - err = rpc_setup_pipedir(clnt, program->pipe_dir_name); - if (err < 0) - goto out; + pipefs_sb = rpc_get_sb_net(net); + if (pipefs_sb) { + err = rpc_setup_pipedir(clnt, program->pipe_dir_name, pipefs_sb); + if (err) + goto out; + } auth = rpcauth_create(args->authflavor, clnt); if (IS_ERR(auth)) { @@ -310,10 +310,12 @@ static int rpc_client_register(const struct rpc_create_args *args, rpc_register_client(clnt); out: + if (pipefs_sb) + rpc_put_sb_net(net); return err; err_auth: - rpc_clnt_remove_pipedir(clnt); + __rpc_clnt_remove_pipedir(clnt); goto out; } diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c index e7ce4b3..c512448 100644 --- a/net/sunrpc/rpc_pipe.c +++ b/net/sunrpc/rpc_pipe.c @@ -1126,6 +1126,7 @@ rpc_fill_super(struct super_block *sb, void *data, int silent) return -ENOMEM; dprintk("RPC: sending pipefs MOUNT notification for net %p%s\n", net, NET_NAME(net)); + mutex_lock(&sn->pipefs_sb_lock); sn->pipefs_sb = sb; err = blocking_notifier_call_chain(&rpc_pipefs_notifier_list, RPC_PIPEFS_MOUNT, @@ -1133,6 +1134,7 @@ rpc_fill_super(struct super_block *sb, void *data, int silent) if (err) goto err_depopulate; sb->s_fs_info = get_net(net); + mutex_unlock(&sn->pipefs_sb_lock); return 0; err_depopulate: @@ -1141,6 +1143,7 @@ err_depopulate: sb); sn->pipefs_sb = NULL; __rpc_depopulate(root, files, RPCAUTH_lockd, RPCAUTH_RootEOF); + mutex_unlock(&sn->pipefs_sb_lock); return err; }