Also, the fs_ is redundant.

Since I've already given one example, my principle-of-least-surprise mind would expect the other accessors to be called:

```
fs_spec    -> spec (maybe specification ?)
fs_file    -> file
fs_vfstype -> virtual_fs_type (maybe virtual_type or vfs_type ?)
fs_mntopts -> mount_options
fs_freq    -> frequency
fs_passno  -> pass_number (maybe pass_num or pass ? ...I have no idea what this actually is)
```