From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757698Ab2CWXPH (ORCPT ); Fri, 23 Mar 2012 19:15:07 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:41939 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753634Ab2CWXPF (ORCPT ); Fri, 23 Mar 2012 19:15:05 -0400 Date: Fri, 23 Mar 2012 16:15:04 -0700 From: Andrew Morton To: Vasiliy Kulikov Cc: Arkadiusz =?UTF-8?Q?Mi=C5=9Bkiewicz?= , linux-kernel@vger.kernel.org, Alexey Dobriyan Subject: Re: [PATCH] proc: fix mount -t proc -o AAA Message-Id: <20120323161504.dced28b9.akpm@linux-foundation.org> In-Reply-To: <20120323171058.GA3279@albatros> References: <201203220903.15360.a.miskiewicz@gmail.com> <20120323171058.GA3279@albatros> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 23 Mar 2012 21:10:58 +0400 Vasiliy Kulikov wrote: > proc_parse_options() inside of proc_mount() runs only once at the boot > time without any given options. So, following umount(2)+mount(2) ignore > mount options: proc_parse_options() is not called as ->s_root is already > initialized. To fix that parse mount options unconditionally. > > Signed-off-by: Vasiliy Kulikov > Reported-by: Arkadiusz Mi__kiewicz > --- > fs/proc/root.c | 9 +++++---- > 1 files changed, 5 insertions(+), 4 deletions(-) > > diff --git a/fs/proc/root.c b/fs/proc/root.c > index 46a15d8..eed44bf 100644 > --- a/fs/proc/root.c > +++ b/fs/proc/root.c > @@ -115,12 +115,13 @@ static struct dentry *proc_mount(struct file_system_type *fs_type, > if (IS_ERR(sb)) > return ERR_CAST(sb); > > + if (!proc_parse_options(options, ns)) { > + deactivate_locked_super(sb); > + return ERR_PTR(-EINVAL); > + } > + > if (!sb->s_root) { > sb->s_flags = flags; > - if (!proc_parse_options(options, ns)) { > - deactivate_locked_super(sb); > - return ERR_PTR(-EINVAL); > - } > err = proc_fill_super(sb); > if (err) { > deactivate_locked_super(sb); I'm surprised. "mount -o remount," doesn't work on a mounted procfs, and nobody noticed until now? The patch looks OK - has it been tested with both valid and invalid mount options? I redid the changelog: From: Vasiliy Kulikov Subject: proc: fix mount -t proc -o AAA The proc_parse_options() call from proc_mount() runs only once at boot time. So on any later mount attempt, any mount options are ignored because ->s_root is already initialized. As a consequence, "mount -o remount," will ignore the options. To fix this, parse the mount options unconditionally. Signed-off-by: Vasiliy Kulikov Reported-by: Arkadiusz Miskiewicz Cc: Alexey Dobriyan Cc: Al Viro Signed-off-by: Andrew Morton --- fs/proc/root.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff -puN fs/proc/root.c~proc-fix-mount-t-proc-o-aaa fs/proc/root.c --- a/fs/proc/root.c~proc-fix-mount-t-proc-o-aaa +++ a/fs/proc/root.c @@ -115,12 +115,13 @@ static struct dentry *proc_mount(struct if (IS_ERR(sb)) return ERR_CAST(sb); + if (!proc_parse_options(options, ns)) { + deactivate_locked_super(sb); + return ERR_PTR(-EINVAL); + } + if (!sb->s_root) { sb->s_flags = flags; - if (!proc_parse_options(options, ns)) { - deactivate_locked_super(sb); - return ERR_PTR(-EINVAL); - } err = proc_fill_super(sb); if (err) { deactivate_locked_super(sb); _