From patchwork Thu Apr 2 23:05:06 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Trond Myklebust X-Patchwork-Id: 11471693 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 6F47281 for ; Thu, 2 Apr 2020 23:07:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3F27C2077D for ; Thu, 2 Apr 2020 23:07:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585868837; bh=tBe1xn5UtOjC6jEuHaEQeUMbqhQsKbohIVkjXsLrBXY=; h=From:To:Subject:Date:List-ID:From; b=dLtA9KBR1MQLorKMhM6jhkjLdf94ilYHyN8AIseWEyo4SQaPnSB0Q+LGrrSdMbbEy ycrO4RqRKkk7D0Val7UaGQ665BQo17KIG8arZtzBXGD73fNczWWl3wnOdT0WMJbbwF dPpoVcAXWd2Pq/GZbiwh3iE5dhSVRWT+wQI5MASk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389586AbgDBXHQ (ORCPT ); Thu, 2 Apr 2020 19:07:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:56166 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388715AbgDBXHQ (ORCPT ); Thu, 2 Apr 2020 19:07:16 -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 D78A32073B for ; Thu, 2 Apr 2020 23:07:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585868836; bh=tBe1xn5UtOjC6jEuHaEQeUMbqhQsKbohIVkjXsLrBXY=; h=From:To:Subject:Date:From; b=1N2AkPI4zkGEVhh8CJp4dioOVwQppS3nZgUkfvgFyzZ1roBiQmwOXUagkVcb5CWwF 7+AyT+PmiyRR6somp0GOqxsqTBqm0g/iNvv1wMMZLboiQgpvXLn5NuWhOz4cv5N2uh 5tqu6yS+w0gQyfaTYDDkfdN8OZ4maL0kc+TVrrpc= From: trondmy@kernel.org To: linux-nfs@vger.kernel.org Subject: [PATCH v2 1/2] NFS: finish_automount() requires us to hold 2 refs to the mount record Date: Thu, 2 Apr 2020 19:05:06 -0400 Message-Id: <20200402230507.795151-1-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 or zero 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..fe19ae280262 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)