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To: Ruslan Ermilov <ru@FreeBSD.org>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Wed, 15 Dec 2004 11:59:01 +0200."
             <20041215095901.GK25967@ip.net.ua> 
Date: Wed, 15 Dec 2004 11:46:18 +0100
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cc: current@FreeBSD.org
Subject: Re: Background fsck is broken 
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In message <20041215095901.GK25967@ip.net.ua>, Ruslan Ermilov writes:
>
>--KjSGHOmKKB2VUiQn
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>
>Hi,
>
>Here's another fsck(8) buglet.  While booting single-user, / is
>mounted read-only, and "fsck -p /" succeeds as expected.  While
>remounting / read-only (e.g., after shutting down from multi-user
>to single-user), it doesn't:

This is working as designed.

The way it works is that when you boot, the root filesystem opens
the device (r=1, w=0, e=0) thereby permitting fsck to open the
device for write.

When the root filesystem is upgraded to RW, the open is opgraded
to (r=1,w=1,e=1) and writing via /dev/mumble is no longer permitted.

Architecturally the way we fsck the root filesystem is highly bogus
and it would be much cleaner if mounted filesystems _always_ were
fsck'ed through a snapshot, but there are a unknown code to be written
to allow that to happen for the case where "unexpected softupdates
inconsistencies" are found.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.