upper layer. Until now, unionfs prevents to use that kind of
file system as upper layer. This time, I changed to allow
that kind of file system as upper layer. By this change, you
can use whiteout not supporting file system (e.g., especially
for tmpfs) as upper layer. It's very useful for combination of
tmpfs as upper layer and read only file system as lower layer.
By difinition, without whiteout support from the file system
backing the upper layer, there is no way that delete and rename
operations on lower layer objects can be done. EOPNOTSUPP is
returned for this kind of operations as generated by VOP_WHITEOUT()
along with any others which would make modifica tions to the
lower layer, such as chmod(1).
This change is suggested by ed.
Submitted by: ed
6f5cfa0928