if (atomic_read(&mnt->mnt_count) > 2) return -EBUSY; return 0;
int ret = 0; spin_lock(&vfsmount_lock); if (propagate_mount_busy(mnt, 2)) ret = -EBUSY; spin_unlock(&vfsmount_lock); return ret;
int may_umount(struct vfsmount *mnt){	if (atomic_read(&mnt->mnt_count) > 2)		return -EBUSY;	return 0;}