kern/55993: getcwd() breaks on unionfs mounted directories

[David Schultz]

On Tue, Jan 27, 2004, Ryan Beasley wrote:
>  Use this link instead:
>  	http://docs.freebsd.org/cgi/mid.cgi?1015415443.3157.2.camel

This patch is probably hiding the problem because getcwd() is
using the cached lookup routine.  However, it seems to introduce a
cache consistency problem, because changes to the underlying
filesystem do not invalidate the appropriate cache entries in the
union layer.

(The email you referenced also mentions that the idea was taken
from nullfs, but I don't see it there.)