I think that this is off-topic now, so I won't respond further in this thread.
Which is to say, the file owner is irrelevant to the
quota system, only
the pathname matters.
Indeed, *because that's the only way you can do it without quotas*, which was my
whole point.
Again, how can any of this be corrupted by free
chown-ing?
For instance imagine I want to pass some customer data to which I have access to you, who
con't have access, for purposes of malice. I know that leaving a world-readable file
will be spotted. So I put them in a file which is 600 in /tmp, and chown it to you. Not
only can't this be easily spotted without system-call auditing (which people
generally do not do), but if it is spotted it looks like it's your fault since you
own the file. File ownership does matter.