Requirements for a File System Implementation

File system implementations differ in how they implement the predefined operations.

However, the logical file system expects that a file system implementation meets the following criteria:

• All vfs and v-node operations must supply a return value:
  • A return value of 0 indicates the operation was successful.
  • A nonzero return value is interpreted as a valid error number (taken from the /usr/include/sys/errno.h file) and returned through the system call interface to the application program.
• All vfs operations must exist for each file system type, but can return an error upon startup. The following are the necessary vfs operations:
  • vfs_cntl
  • vfs_mount
  • vfs_root
  • vfs_statfs
  • vfs_sync
  • vfs_unmount
  • vfs_vget
  • vfs_quotactl

For a complete list of file system operations, see List of Virtual File System Operations.