From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759675AbZEKWPb (ORCPT ); Mon, 11 May 2009 18:15:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758102AbZEKWPQ (ORCPT ); Mon, 11 May 2009 18:15:16 -0400 Received: from e5.ny.us.ibm.com ([32.97.182.145]:43828 "EHLO e5.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757443AbZEKWPO (ORCPT ); Mon, 11 May 2009 18:15:14 -0400 Date: Mon, 11 May 2009 15:15:02 -0700 From: Sukadev Bhattiprolu To: Marc Dionne Cc: Eric Paris , Eric Paris , Christoph Hellwig , Andrew Morton , Alan Cox , serue@us.ibm.com, hpa@zytor.com, sukadev@us.ibm.com, linux-kernel@vger.kernel.org, jbacik@redhat.com Subject: Re: [v3][PATCH 5/5] Merge code for single andmultiple-instancemounts Message-ID: <20090511221502.GA32530@linux.vnet.ibm.com> References: <20090307180816.GA30072@us.ibm.com> <20090307181232.GF30072@us.ibm.com> <7e0fb38c0905071335g7ebe972xa82faa1161f7ff0b@mail.gmail.com> <20090507212429.GA24064@linux.vnet.ibm.com> <1241735609.2907.4.camel@dhcp231-142.rdu.redhat.com> <20090507231844.GA27609@linux.vnet.ibm.com> <20090507232110.GB27609@linux.vnet.ibm.com> <4A04F5D7.2050909@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A04F5D7.2050909@gmail.com> X-Operating-System: Linux 2.0.32 on an i486 User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Marc Dionne [marc.c.dionne@gmail.com] wrote: > On 05/07/2009 07:21 PM, Sukadev Bhattiprolu wrote: >> Er. I meant add following lines after the memset(). >> >> | opts->mode = DEVPTS_DEFAULT_MODE; >> | opts->ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; > > Adding those two lines (with . instead of ->) does fix the issue for me, > thanks. > > | > Of course we would still need to understand if/ > | > why this patch changes the settings. > > That particular patch changed things because the original memcpy in > new_pts_mount() did this: > > memcpy(&fsi->mount_opts, opts, sizeof(opts)); > > where opts was a pointer, not a structure. So only the first few bytes of > the blank opts actually got copied over. The patch moved this memcpy to > devpts_get_sb() and in the process fixed the sizeof error. Here is a cleaner fix - When user space (/etc/rc.sysinit on RHEL5) mounts devpts, this problem might be masked since the mount system call could pass a non-NULL 'data' parmeter to devpts_get_sb(). I tested this patch by directly calling the system call mount() with a NULL data parameter. If you/Eric/Peter can confirm that this works for you, I will send this patch to Andrew. Thanks, --- >>From 2f7746f4df78ff57125c4714f0cd64e739ccf804 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Mon, 11 May 2009 13:11:11 -0700 Subject: [PATCH] devpts: Correctly set default options devpts_get_sb() calls memset(0) to clear mount options and calls parse_mount_options() if user specified any mount options. The memset(0) is bogus since the 'mode' and 'ptmxmode' options are non-zero by default. parse_mount_options() restores options to default anyway and can properly deal with NULL mount options. So in devpts_get_sb() remove memset(0) and call parse_mount_options() even for NULL mount options. Bug reported by Eric Paris: http://lkml.org/lkml/2009/5/7/448. Signed-off-by: Sukadev Bhattiprolu (sukadev@us.ibm.com) --- fs/devpts/inode.c | 18 ++++++++++++------ 1 files changed, 12 insertions(+), 6 deletions(-) diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index 63a4a59..b7a954e 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -90,6 +90,15 @@ static inline struct super_block *pts_sb_from_inode(struct inode *inode) #define PARSE_MOUNT 0 #define PARSE_REMOUNT 1 +/* + * parse_mount_options(): + * Set @opts to mount options specified in @data. If an option is not + * specified in @data, set it to its default value. The exception is + * 'newinstance' option which can only be set/cleared on a mount (i.e. + * cannot be changed during remount). + * + * Note: @data may be NULL (in which case all options are set to default). + */ static int parse_mount_options(char *data, int op, struct pts_mount_opts *opts) { char *p; @@ -355,12 +364,9 @@ static int devpts_get_sb(struct file_system_type *fs_type, struct pts_mount_opts opts; struct super_block *s; - memset(&opts, 0, sizeof(opts)); - if (data) { - error = parse_mount_options(data, PARSE_MOUNT, &opts); - if (error) - return error; - } + error = parse_mount_options(data, PARSE_MOUNT, &opts); + if (error) + return error; if (opts.newinstance) s = sget(fs_type, NULL, set_anon_super, NULL);