From patchwork Mon Jun 10 14:40:01 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stanislav Kinsbursky X-Patchwork-Id: 2697811 Return-Path: X-Original-To: patchwork-linux-nfs@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id 2FA02DFF68 for ; Mon, 10 Jun 2013 14:41:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753658Ab3FJOkX (ORCPT ); Mon, 10 Jun 2013 10:40:23 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:35829 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753634Ab3FJOkV (ORCPT ); Mon, 10 Jun 2013 10:40:21 -0400 Received: from localhost.localdomain ([10.30.16.179]) by relay.sw.ru (8.13.4/8.13.4) with ESMTP id r5AEe1h2010471; Mon, 10 Jun 2013 18:40:02 +0400 (MSK) Subject: [PATCH 1/3] SUNRPC: fix races on PipeFS UMOUNT 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: Mon, 10 Jun 2013 18:40:01 +0400 Message-ID: <20130610144001.7498.41629.stgit@localhost.localdomain> In-Reply-To: <20130610143725.7498.72391.stgit@localhost.localdomain> References: <20130610143725.7498.72391.stgit@localhost.localdomain> User-Agent: StGit/0.16 MIME-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org 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 | 7 ++++++- net/sunrpc/rpc_pipe.c | 3 +++ 2 files changed, 9 insertions(+), 1 deletions(-) -- 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 diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 5a750b9..cf5b226 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -170,7 +170,10 @@ rpc_setup_pipedir(struct rpc_clnt *clnt, const char *dir_name) if (!pipefs_sb) return 0; dentry = rpc_setup_pipedir_sb(pipefs_sb, clnt, dir_name); - rpc_put_sb_net(net); + /* + * PipeFS superblock will be put after client registration to prevent + * races with PipeFS mount call. + */ if (IS_ERR(dentry)) return PTR_ERR(dentry); clnt->cl_dentry = dentry; @@ -369,11 +372,13 @@ 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_register_client(clnt); + rpc_put_sb_net(xprt->xprt_net); return clnt; out_no_auth: rpc_clnt_remove_pipedir(clnt); out_no_path: + rpc_put_sb_net(xprt->xprt_net); kfree(clnt->cl_principal); out_no_principal: rpc_free_iostats(clnt->cl_metrics); 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; }