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From: Jörn Engel (joern_at_wohnheim.fh-wedel.de)
Date: Tue 03 Aug 2004 - 17:21:23 BST

On Tue, 3 August 2004 18:06:34 +0200, Herbert Poetzl wrote:
> sounds good, btw, I heard the copious locking was
> removed? (matt told so, if I got him right)

Yes, that was an interesting idea but turned out to be useless.

> addressed in linux-vserver. we are using something
> called immutable linkage invert or immutable unlink
> (or hundred other names folks invented ;) but it
> basically works like this:
> you create a hardlink of a file for several servers
> (sometimes to a template, sometimes just between
> the servers), then set the immutable attribute (which
> can not be reverted inside a virtual server), and
> an additional attribute (now called iunlink) which
> permits the user to unlink such an otherwise immutable
> hardlink reference ...
> this is sufficient for most package updates and
> similar but of course a smart solution (CoW*) would
> be appreciated ...

In other words, you use a hack just like everyone else. Madcow is a
hack as well, no doubt. My non-existing impementation of what's to a
great deal Pavel's design should be sane - finally.

> btw, the process of identifying identical files and
> combining them into an immutable but unlinkable hard
> reference is (here) called unification, and is done
> by some userspace tools ...

Great! I would have written something like that as well, but if it
already exists and the code is not unhealthy to look at... do you have
a url or something such?

> I'm willing to help where it is required, as much
> as my time permits ...

I appreciate that. First thing would be a comment on my interface
design. Will document that asap (but not today anymore).


Fools ignore complexity.  Pragmatists suffer it.
Some can avoid it.  Geniuses remove it.
-- Perlis's Programming Proverb #58, SIGPLAN Notices, Sept.  1982
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