Translate the file-system identifier string fsname into a file-system type index.
2
Translate the file-system type index fs_index into a null-terminated file-system identifier string. This string will be written to the buffer pointed to by buf. Make sure that buf has enough space to accept the string.
3
Return the total number of file system types currently present in the kernel.
The numbering of the file-system type indexes begins with zero.