Kernel Extensions and Device Support Programming Concepts

Configuring a Virtual File System

The kernel maintains a table of active file system types. A file system implementation must be registered with the kernel before a request to mount a virtual file system (VFS) of that type can be honored. Two kernel services, gfsadd and gfsdel, are supplied for adding a file system type to the gfs file system table.

These are the steps that must be followed to get a file system configured.

1. A user-level routine must call the sysconfig subroutine requesting that the code for the virtual file system be loaded.
2. The user-level routine must then request, again by calling the sysconfig subroutine, that the virtual file system be configured. The name of a VFS-specific configuration routine must be specified.
3. The virtual file system-specific configuration routine calls the gfsadd kernel service to have the new file system added to the gfs table. The gfs table that the configuration routine passes to the gfsadd kernel service contains a pointer to an initialization routine. This routine is then called to do any further virtual file system-specific initialization.
4. The file system is now operational.