Re: Union file system

Alan Cox (
Wed, 27 Nov 1996 23:15:28 +0000 (GMT)

> For any interested folks, there is a comprehensive discussion of Union
> file systems in the book "Unix Internals" by Uresh Vahalia
> (Prentice-Hall, 1996. ISBN 0-13-101908-2). This book is well worth
> owning as a reference for some of the deeper technical topics that pop

A union FS btw is _horrible_ to do well. Consider a process with an mmap
of a union FS object that is replaced by a file elsewhere and keeping
the mmap coherency correct. Now truncate the file at the same instant
and enjoy