And "Cleanly" Un-mount-able

When a file-system is unmounted, its "put_super" super-block operation is invoked. stamfs_put_super() does:

• Release the buffer_head-s we used for storing super-block related data (the super-block, the inode index block and the free list block).
• Free the memory used for storing the STAMFS super-block's meta-data.

Originally written by guy keren