From patchwork Thu Apr 2 20:30:17 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Trond Myklebust X-Patchwork-Id: 11471481 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A7613159A for ; Thu, 2 Apr 2020 20:32:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7C73520678 for ; Thu, 2 Apr 2020 20:32:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585859553; bh=Gqme0TZgXCGLbqU2j6oV59NYlkYpiJ+m2BbRFkg5tE8=; h=From:To:Subject:Date:List-ID:From; b=i/Gecorae3KlowEyw1AQDihMz5dQVyYR8e8eyc478E46w7kvBm1l/Fy0pAwkeOLi8 s6TF27UG/Uk9sab89Omo0IZ62q/V1eTuNJ3ucidhoeNM4dV+5w0rFs/xMw1/eOnEWx Si1QnLvnsJBLY8UR814SZ7bcA3I+SNCSmBJbjwtA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730837AbgDBUcc (ORCPT ); Thu, 2 Apr 2020 16:32:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:42082 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728225AbgDBUcc (ORCPT ); Thu, 2 Apr 2020 16:32:32 -0400 Received: from localhost.localdomain (c-68-36-133-222.hsd1.mi.comcast.net [68.36.133.222]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 194BF20678 for ; Thu, 2 Apr 2020 20:32:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585859552; bh=Gqme0TZgXCGLbqU2j6oV59NYlkYpiJ+m2BbRFkg5tE8=; h=From:To:Subject:Date:From; b=knAxV0vrhYhg5FsICrQlZ7zRajye3jw5MicRSpUNokfC3a0cc+QbiEy8SWfSvVpG/ UFqaHk4grwssXT9bSXrw64yNjTQ5nQFKhDlJfKzsD5lUhoJ3uxKR+OA1nDVpJM8noU pKVj2UqJHizE7BJswtnZ1nJtjGz7LNOlvVF293MA= From: trondmy@kernel.org To: linux-nfs@vger.kernel.org Subject: [PATCH 1/2] NFS: finish_automount() requires us to hold 2 refs to the mount record Date: Thu, 2 Apr 2020 16:30:17 -0400 Message-Id: <20200402203018.385154-1-trondmy@kernel.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org From: Trond Myklebust We must not return from nfs_d_automount() without holding 2 references to the mount record. Doing so, will trigger the BUG() in finish_automount(). Also ensure that we don't try to reschedule the automount timer with a negative timeout value. Fixes: 22a1ae9a93fb ("NFS: If nfs_mountpoint_expiry_timeout < 0, do not expire submounts") Cc: stable@vger.kernel.org # v5.5+ Signed-off-by: Trond Myklebust --- fs/nfs/namespace.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c index da67820462f2..50b162dd88f5 100644 --- a/fs/nfs/namespace.c +++ b/fs/nfs/namespace.c @@ -145,6 +145,7 @@ struct vfsmount *nfs_d_automount(struct path *path) struct vfsmount *mnt = ERR_PTR(-ENOMEM); struct nfs_server *server = NFS_SERVER(d_inode(path->dentry)); struct nfs_client *client = server->nfs_client; + int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout); int ret; if (IS_ROOT(path->dentry)) @@ -190,12 +191,12 @@ struct vfsmount *nfs_d_automount(struct path *path) if (IS_ERR(mnt)) goto out_fc; - if (nfs_mountpoint_expiry_timeout < 0) + mntget(mnt); /* prevent immediate expiration */ + if (timeout < 0) goto out_fc; - mntget(mnt); /* prevent immediate expiration */ mnt_set_expiry(mnt, &nfs_automount_list); - schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); + schedule_delayed_work(&nfs_automount_task, timeout); out_fc: put_fs_context(fc); @@ -233,10 +234,11 @@ const struct inode_operations nfs_referral_inode_operations = { static void nfs_expire_automounts(struct work_struct *work) { struct list_head *list = &nfs_automount_list; + int timeout = READ_ONCE(nfs_mountpoint_expiry_timeout); mark_mounts_for_expiry(list); - if (!list_empty(list)) - schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout); + if (!list_empty(list) && timeout >= 0) + schedule_delayed_work(&nfs_automount_task, timeout); } void nfs_release_automount_timer(void)