Originally from: Herbert Poetzl <herbert at 13thfloor.at> 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 <haveblue at us.ibm.com> --- lxc-dave/fs/namespace.c | 24 ++++++++++++++++++++++-- lxc-dave/fs/open.c | 2 +- 2 files changed, 23 insertions(+), 3 deletions(-) diff -puN fs/namespace.c~23-24-honor-r-w-changes-at-do-remount-time fs/namespace.c --- lxc/fs/namespace.c~23-24-honor-r-w-changes-at-do-remount-time 2006-12-11 14:22:12.000000000 -0800 +++ lxc-dave/fs/namespace.c 2006-12-11 14:22:12.000000000 -0800 @@ -399,7 +399,7 @@ 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_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw"); for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { if (mnt->mnt_sb->s_flags & fs_infop->flag) seq_puts(m, fs_infop->str); @@ -1023,6 +1023,23 @@ out: } EXPORT_SYMBOL_GPL(mnt_want_write); +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 @@ -1044,7 +1061,10 @@ 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~23-24-honor-r-w-changes-at-do-remount-time fs/open.c --- lxc/fs/open.c~23-24-honor-r-w-changes-at-do-remount-time 2006-12-11 14:22:12.000000000 -0800 +++ lxc-dave/fs/open.c 2006-12-11 14:22:12.000000000 -0800 @@ -401,7 +401,7 @@ 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: _