From patchwork Thu Dec 15 11:34:26 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 9475871 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 3BC9560825 for ; Thu, 15 Dec 2016 11:43:01 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2ABFE2870F for ; Thu, 15 Dec 2016 11:43:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1FD5B2875E; Thu, 15 Dec 2016 11:43:01 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CD1032870F for ; Thu, 15 Dec 2016 11:43:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755793AbcLOLmu (ORCPT ); Thu, 15 Dec 2016 06:42:50 -0500 Received: from mx1.redhat.com ([209.132.183.28]:36894 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755789AbcLOLmt (ORCPT ); Thu, 15 Dec 2016 06:42:49 -0500 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AB8A0624B9; Thu, 15 Dec 2016 11:34:32 +0000 (UTC) Received: from tleilax.poochiereds.net (ovpn-116-139.rdu2.redhat.com [10.10.116.139]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uBFBYTZL023552; Thu, 15 Dec 2016 06:34:31 -0500 From: Jeff Layton To: ceph-devel@vger.kernel.org Cc: zyan@redhat.com, sage@redhat.com, idryomov@gmail.com, linux-fsdevel@vger.kernel.org, dhowells@redhat.com, viro@ZenIV.linux.org.uk Subject: [PATCH v4 2/5] ceph: clean up unsafe d_parent accesses in build_dentry_path Date: Thu, 15 Dec 2016 06:34:26 -0500 Message-Id: <1481801669-4916-3-git-send-email-jlayton@redhat.com> In-Reply-To: <1481801669-4916-1-git-send-email-jlayton@redhat.com> References: <1481801669-4916-1-git-send-email-jlayton@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Thu, 15 Dec 2016 11:34:32 +0000 (UTC) Sender: ceph-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP While we hold a reference to the dentry when build_dentry_path is called, we could end up racing with a rename that changes d_parent. Handle that situation correctly, by using the rcu_read_lock to ensure that the parent dentry and inode stick around long enough to safely check ceph_snap and ceph_ino. Link: http://tracker.ceph.com/issues/18148 Signed-off-by: Jeff Layton --- fs/ceph/mds_client.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 20b241aafcee..03c82953ac68 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -1799,13 +1799,18 @@ static int build_dentry_path(struct dentry *dentry, int *pfreepath) { char *path; + struct inode *dir; - if (ceph_snap(d_inode(dentry->d_parent)) == CEPH_NOSNAP) { - *pino = ceph_ino(d_inode(dentry->d_parent)); + rcu_read_lock(); + dir = d_inode_rcu(dentry->d_parent); + if (dir && ceph_snap(dir) == CEPH_NOSNAP) { + *pino = ceph_ino(dir); + rcu_read_unlock(); *ppath = dentry->d_name.name; *ppathlen = dentry->d_name.len; return 0; } + rcu_read_unlock(); path = ceph_mdsc_build_path(dentry, ppathlen, pino, 1); if (IS_ERR(path)) return PTR_ERR(path);