static int can_umount(const struct path *path, int flags)
{
	struct mount *mnt = real_mount(path->mnt);

	if (!may_mount())
		return -EPERM;
	if (path->dentry != path->mnt->mnt_root)
		return -EINVAL;
	if (!check_mnt(mnt))
		return -EINVAL;
	if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */
		return -EINVAL;
	if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN))
		return -EPERM;
	return 0;
}
static int can_umount(const struct path *path, int flags)
{
	struct mount *mnt = real_mount(path->mnt);

	if (!may_mount())
		return -EPERM;
	if (path->dentry != path->mnt->mnt_root)
		return -EINVAL;
	if (!check_mnt(mnt))
		return -EINVAL;
	if (mnt->mnt.mnt_flags & MNT_LOCKED)  
		return -EINVAL;
	if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN))
		return -EPERM;
	return 0;
}