Understanding Generic I-nodes (G-nodes)

A generic i-node (g-node) is the representation of an object in a file system implementation. There is a one-to-one correspondence between a g-node and an object in a file system implementation. Each g-node represents an object owned by the file system implementation.

Each file system implementation is responsible for allocating and destroying g-nodes. The g-node then serves as the interface between the logical file system and the file system implementation. Calls to the file system implementation serve as requests to perform an operation on a specific g-node.

A g-node is needed, in addition to the file system i-node, because some file system implementations may not include the concept of an i-node. Thus the g-node structure substitutes for whatever structure the file system implementation may have used to uniquely identify a file system object.

The logical file system relies on the file system implementation to provide valid data for the following fields in the g-node: