From owner-freebsd-arch  Fri Mar 30 10:32:44 2001
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To: Robert Watson <rwatson@freebsd.org>
Subject: Re: Background Fsck 
Cc: arch@freebsd.org
In-Reply-To: Your message of "Fri, 30 Mar 2001 09:05:10 EST."
             <Pine.NEB.3.96L.1010330090228.2647I-100000@fledge.watson.org> 
Date: Fri, 30 Mar 2001 10:32:41 -0800
From: Kirk McKusick <mckusick@mckusick.com>
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	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.

	Kirk

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