The simplest way to ensure that a filesystem listed in fstab is really mounted is to include the attribute _netdev in the relevant line. Unfortunately it doesn't always work! If the mount operation depends on something else being already mounted, the _netdev attribute is insufficient. This situation is discussed a length in how to setup ubuntu that fstab runs after network is connected?.
But that solution looks fairly complex to me. So is there a simple way to check if a filesystem is surely mounted that works under all circumstances -- in other words, provides a foolproof way of achieving what _netdev tries to achieve?