From mboxrd@z Thu Jan 1 00:00:00 1970 From: Artem Bityutskiy Subject: [RFC] [PATCH] vfs: remount all file-systems R/O on emergency remount. Date: Fri, 24 Aug 2012 10:26:06 +0300 Message-ID: <1345793166-14230-1-git-send-email-dedekind1@gmail.com> Cc: Linux FS Maling List , Linux Kernel Maling List , Alexander Stein To: Al Viro Return-path: Received: from mga01.intel.com ([192.55.52.88]:16952 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750827Ab2HXHZz (ORCPT ); Fri, 24 Aug 2012 03:25:55 -0400 Sender: linux-fsdevel-owner@vger.kernel.org List-ID: From: Artem Bityutskiy Currently the emergency remount (triggered by Sysrq-u) re-mounting only those file-systems R/O, which have an associated block device (sb->s_bdev). This does not work for file-systems like UBIFS and JFFS2 which work on top of MTD devices (character devices) and always have sb->s_bdev = NULL. This also does not work for tmpfs. Most probably the intention was to avoid re-mounting R/O file-systems like procfs, sysfs, cgroup, and debugfs. However, I do not really see why not to remount them R/O as well in case of emergency. This patch removes the 'sb->s_bdev != NULL' check from 'do_emergency_remount()', so _all_ file-systems will be re-mounted R/O. Tested in Fedora - all file-systems (ext4, ubifs, procfs, sysfs, cgroup, and debugfs) become R/O on Sysrq-u with this patch. Signed-off-by: Artem Bityutskiy --- fs/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/super.c b/fs/super.c index 0902cfa..95cf173 100644 --- a/fs/super.c +++ b/fs/super.c @@ -812,7 +812,7 @@ static void do_emergency_remount(struct work_struct *work) sb->s_count++; spin_unlock(&sb_lock); down_write(&sb->s_umount); - if (sb->s_root && sb->s_bdev && (sb->s_flags & MS_BORN) && + if (sb->s_root && (sb->s_flags & MS_BORN) && !(sb->s_flags & MS_RDONLY)) { /* * What lock protects sb->s_flags?? -- 1.7.10.4