On Wed, Feb 14, 2018 at 02:48:14PM -0500, Andrew Bell wrote:
> Why not early return if size == 0 and avoid the call to __fwritex
> altogether?
>

Because it's a rare corner case? Here, there's also locking correctness
to consider: fwrite() has to block until f is unlocked, irrespective of
parameters. So there's no real benefit to doing an early return.