From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932388AbWGLSRi (ORCPT ); Wed, 12 Jul 2006 14:17:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932398AbWGLSRi (ORCPT ); Wed, 12 Jul 2006 14:17:38 -0400 Received: from e36.co.us.ibm.com ([32.97.110.154]:25246 "EHLO e36.co.us.ibm.com") by vger.kernel.org with ESMTP id S932388AbWGLSRe (ORCPT ); Wed, 12 Jul 2006 14:17:34 -0400 Subject: [RFC][PATCH 27/27] honor r/w changes at do_remount() time To: viro@ftp.linux.org.uk Cc: serue@us.ibm.com, linux-kernel@vger.kernel.org, Dave Hansen From: Dave Hansen Date: Wed, 12 Jul 2006 11:17:29 -0700 References: <20060712181709.5C1A4353@localhost.localdomain> In-Reply-To: <20060712181709.5C1A4353@localhost.localdomain> Message-Id: <20060712181729.9A552320@localhost.localdomain> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Originally from: Herbert Poetzl This is the core of the read-only bind mount patch set. Note that this does _not_ add a "ro" option directly to the bind mount operation. If you require such a mount, you must first do the bind, then follow it up with a 'mount -o remount,ro' operation. Signed-off-by: Dave Hansen --- lxc-dave/fs/namespace.c | 28 ++++++++++++++++++++++++---- lxc-dave/fs/open.c | 2 +- 2 files changed, 25 insertions(+), 5 deletions(-) diff -puN fs/namespace.c~C-D8-actually-add-flags fs/namespace.c --- lxc/fs/namespace.c~C-D8-actually-add-flags 2006-07-12 11:09:44.000000000 -0700 +++ lxc-dave/fs/namespace.c 2006-07-12 11:09:45.000000000 -0700 @@ -381,6 +381,7 @@ static int show_vfsmnt(struct seq_file * char *set_str; char *unset_str; } fs_info[] = { + { MS_RDONLY, MNT_READONLY, "ro", "rw" }, { MS_SYNCHRONOUS, 0, ",sync", NULL }, { MS_DIRSYNC, 0, ",dirsync", NULL }, { MS_MANDLOCK, 0, ",mand", NULL }, @@ -396,17 +397,16 @@ static int show_vfsmnt(struct seq_file * seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); seq_putc(m, ' '); mangle(m, mnt->mnt_sb->s_type->name); - seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw"); + seq_putc(m, ' '); for (i = 0; i < ARRAY_SIZE(fs_info); i++) { struct proc_fs_info *fs_infop = &fs_info[i]; char *str = NULL; if ((mnt->mnt_sb->s_flags & fs_infop->s_flag) || - mnt_flag_set(mnt, fs_infop->mnt_flag)) + (mnt->mnt_flags & fs_infop->mnt_flag)) str = fs_infop->set_str; else str = fs_infop->unset_str; - if (mnt->mnt_flags & fs_infop->flag) if (str) seq_puts(m, str); } @@ -1024,6 +1024,23 @@ out: return err; } +static int change_mount_flags(struct vfsmount *mnt, int ms_flags) +{ + int error = 0; + int readonly_request = 0; + + if (ms_flags & MS_RDONLY) + readonly_request = 1; + if (readonly_request == __mnt_is_readonly(mnt)) + return 0; + + if (readonly_request) + error = mnt_make_readonly(mnt); + else + __mnt_unmake_readonly(mnt); + return error; +} + /* * change filesystem flags. dir should be a physical root of filesystem. * If you've mounted a non-root directory somewhere and want to do remount @@ -1045,7 +1062,10 @@ static int do_remount(struct nameidata * return -EINVAL; down_write(&sb->s_umount); - err = do_remount_sb(sb, flags, data, 0); + if (flags & MS_BIND) + err = change_mount_flags(nd->mnt, flags); + else + err = do_remount_sb(sb, flags, data, 0); if (!(sb->s_flags & MS_RDONLY)) mnt_flags |= MNT_SB_WRITABLE; if (!err) diff -puN fs/open.c~C-D8-actually-add-flags fs/open.c --- lxc/fs/open.c~C-D8-actually-add-flags 2006-07-12 11:09:38.000000000 -0700 +++ lxc-dave/fs/open.c 2006-07-12 11:09:45.000000000 -0700 @@ -546,7 +546,7 @@ asmlinkage long sys_faccessat(int dfd, c special_file(nd.dentry->d_inode->i_mode)) goto out_path_release; - if(IS_RDONLY(nd.dentry->d_inode)) + if(__mnt_is_readonly(nd.mnt) || IS_RDONLY(nd.dentry->d_inode)) res = -EROFS; out_path_release: _