From: Peter Chubb <peter@chubb.wattle.id.au>

Add two new system calls, statfs64 and fstatfs64.  This has been needed
sincew the 64-bit sector_t merge - the current structures will overflow.

- Use a common interface (vfs_statfs) with the rest of the kernel,

- convert to 32-bit at (f)statfs time.

- New field f_frsize gives underlying fragment size for the filesystem.
  (Solaris has this, and the Open Group describe it).

- The old statfs syscalls will now return -EOVERFLOW if the device was
  too large to be represented inthe old data structures.

The new system calls take a size_t argument, which is the size of the
structure to be filled in (as requested by Ben LaHaise), to `futureproof' the
interface.

Has been reviewed by the arch maintainers and by Ulrich Drepper.