Re: [Vserver] vhashify on Debian / CoW links not breaking on chmod/chown?

From: Grzegorz Nosek <grzegorz.nosek_at_gmail.com>
Date: Thu 02 Feb 2006 - 12:02:51 GMT
Message-ID: <121a28810602020402s2db61e2ei@mail.gmail.com>

2006/2/1, Herbert Poetzl <herbert@13thfloor.at>:
> > - If I modify a file's contents the CoW link is broken properly but
> > after a chmod or chown the link is not broken and I get -EPERM (as the
> > files are marked immutable) - is this expected behaviour? In such a
> > situation the links aren't exactly CoW...
>
> interesting observation, well, strictly speaking
> chmod or chow are no writes, so CoW is not involved,
> but I will look into extending the CoW behaviour
> to those operations in the future ...
>

Yeah, I know chown isn't really a write but I thought (or maybe I
felt) that unification shouldn't ever cause an -EPERM error (just
break the link instead).

It definitely isn't a show stopper for me as I found this behaviour
after unifying a bit too much of the test vservers but it would be a
nice feature to have. I came across this when one of my postinstall
scripts barfed when it tried to sanitise permissions on some files
(just a blind chown/chmod without prior testing).

BTW, how does the unification react to files owned by different users?
i.e. /some/file is totally identical between two vservers (wrt.
contents, timestamps and access mode) but is owned by different users
(e.g. root:admin on both but on one group admin is gid 7000 and on the
other it is 8000 or whatever). AIUI it won't be unified at all, right?

Best regards,
 Grzegorz Nosek
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Received on Thu Feb 2 12:03:32 2006

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