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Date:      Fri, 30 Mar 2001 15:38:10 -0800
From:      Cy Schubert - ITSD Open Systems Group <Cy.Schubert@uumail.gov.bc.ca>
To:        Kirk McKusick <mckusick@mckusick.com>
Cc:        Robert Watson <rwatson@FreeBSD.ORG>, arch@FreeBSD.ORG
Subject:   Re: Background Fsck 
Message-ID:  <200103302338.f2UNcTN08783@cwsys.cwsent.com>
In-Reply-To: Your message of "Fri, 30 Mar 2001 10:32:41 PST." <200103301832.KAA10132@beastie.mckusick.com> 

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In message <200103301832.KAA10132@beastie.mckusick.com>, Kirk McKusick 
writes:
> 	Date: Fri, 30 Mar 2001 09:05:10 -0500 (EST)
> 	From: Robert Watson <rwatson@freebsd.org>
> 	To: Kirk McKusick <mckusick@mckusick.com>
> 	cc: arch@freebsd.org
> 	Subject: Re: Background Fsck 
> 
> 	Kirk,
> 
> 	I haven't had a chance to look at the tunefs source lately,
> 	but quick question: does tunefs block the setting of the
> 	soft updates flag on a dirty file system?  It seems to me
> 	that, if it doesn't, a possible nasty sequence of events
> 	is: system does unclean shutdown without soft updates,
> 	administrator (possibly not realizing this) boots to
> 	single-user mode, and sets soft updates, then attempts to
> 	enter multi-user mode, where fsck says "ah, soft updates,
> 	doesn't matter if it's unclean, let's background fsck".
> 	Shortly thereafter, an inconsistency is discovered and the
> 	system panics.  As such, tunefs should only allow the
> 	setting of soft updates on a file system marked clean.  It
> 	may already do this, but figured I should ask.
> 
> 	Thanks!
> 
> 	Robert N M Watson             FreeBSD Core Team, TrustedBSD Project
> 	robert@fledge.watson.org      NAI Labs, Safeport Network Services
> 
> Your observation is absolutely correct. I have modified tunefs
> exactly as you suggest and will be checking in that change as 
> part of my next set of updates which enable background fsck. I
> will also note in passing that this is yet another reason why
> the setting of soft updates needs to be done in newfs and/or
> tunefs and not as an option in /etc/fstab.

I would think the integrity checking patch to tunefs(8) should be in 
-stable too.  Could this little change be MFC'd into -stable sometime 
soon?


Regards,                         Phone:  (250)387-8437
Cy Schubert                        Fax:  (250)387-5766
Team Leader, Sun/Alpha Team   Internet:  Cy.Schubert@osg.gov.bc.ca
Open Systems Group, ITSD, ISTA
Province of BC




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