From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932990AbeCMMSN (ORCPT ); Tue, 13 Mar 2018 08:18:13 -0400 Received: from mail-wr0-f194.google.com ([209.85.128.194]:39023 "EHLO mail-wr0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932904AbeCMMSJ (ORCPT ); Tue, 13 Mar 2018 08:18:09 -0400 X-Google-Smtp-Source: AG47ELv/NesV5APlA4SZvi/0X4osd8vUPFbemJe/Bc5ZIpCvyLYdaRk4DO3dy3MuCoEPOCiqRBPtBQ== From: Christian Brauner To: viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org, ebiederm@xmission.com, torvalds@linux-foundation.org Cc: containers@lists.linux-foundation.org, Christian Brauner Subject: [PATCH 3/4 v5] devpts: comment devpts_mntget() Date: Tue, 13 Mar 2018 13:17:12 +0100 Message-Id: <20180313121713.32551-4-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20180313121713.32551-1-christian.brauner@ubuntu.com> References: <20180313121713.32551-1-christian.brauner@ubuntu.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Signed-off-by: Christian Brauner --- ChangeLog v4->v5: * patch added ChangeLog v3->v4: * patch not present ChangeLog v2->v3: * patch not present ChangeLog v1->v2: * patch not present ChangeLog v0->v1: * patch not present --- fs/devpts/inode.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index 542364bf923e..e072e955ce33 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -152,6 +152,24 @@ static int devpts_ptmx_path(struct path *path) return 0; } +/* + * Try to find a suitable devpts filesystem. We support the following + * scenarios: + * - The ptmx device node is located in the same directory as the devpts + * mount where the pts device nodes are located. + * This is e.g. the case when calling open on the /dev/pts/ptmx device + * node when the devpts filesystem is mounted at /dev/pts. + * - The ptmx device node is located outside the devpts filesystem mount + * where the pts device nodes are located. For example, the ptmx device + * is a symlink, separate device node, or bind-mount. + * A supported scenario is bind-mounting /dev/pts/ptmx to /dev/ptmx and + * then calling open on /dev/ptmx. In this case a suitable pts + * subdirectory can be found in the common parent directory /dev of the + * devpts mount and the ptmx bind-mount, after resolving the /dev/ptmx + * bind-mount. + * If no suitable pts subdirectory can be found this function will fail. + * This is e.g. the case when bind-mounting /dev/pts/ptmx to /ptmx. + */ struct vfsmount *devpts_mntget(struct file *filp, struct pts_fs_info *fsi) { struct path path; -- 2.15.1