NFS: file too large

[Rick Macklem]

> 
> BTW, why not make away with the test altogether?
> 
Well, since a server specifies the maximum file size it can
handle, it seems good form to check for that in the client.
(Although I'd agree that a server shouldn't crash if a read/write
 that goes beyond that limit.)

Also, as Matt notes, off_t is signed. As such, it looks to me like
the check could mess up if uio_offset it right near 0x7fffffffffffffff,
so that uio->ui_offset + uio->uio_resid ends up negative. I think the
check a little above that for uio_offset < 0 should also check
uio_offset + uio_resid < 0 to avoid this.

rick