*BSD News Article 67941


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From: j@uriah.heep.sax.de (J Wunsch)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: panic: update: rofs mod
Date: 7 May 1996 20:44:10 GMT
Organization: Private BSD site, Dresden
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References: <Dqr3JD.C4o.0.macbeth@cogsci.ed.ac.uk>
Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch)
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richard@cogsci.ed.ac.uk (Richard Tobin) wrote:

> I have a removeable disk containing a filesystem which can not be
> mounted read-write because it was not cleanly dismounted.  If I mount
> it read-only, when I umount it the system panics with the message
> "update: rofs mod".

You ought to fsck unclean file systems before mounting (regardless of
whether you mount it r/o or r/w -- it's only that the system tries to
protect itself by denied r/w for unclean file systems).

> It's possible that this is technically not a bug, because it's a file
> system that's been mounted under the Hurd, so who knows what
> non-standard extensions have been used.  On the other hand, I'm
> somewhat surprised that it produces this error.

For performance reasons, the system must rely on the file system being
in a consistent state.  It's impractical to check each and any cross-
reference, link counter, bitmap entry etc. just when it's being
referenced.  It's indeed a bit surprising that it tries to update a
r/o file system at all -- but i would only consider this a system bug
if it also happens for a clean file system.

-- 
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)