misc/118160: unable to mount / rw while booting 7.0-BETA3
yuri at rawbw.com
Tue Nov 27 22:40:03 PST 2007
The following reply was made to PR bin/118160; it has been noted by GNATS.
From: Yuri <yuri at rawbw.com>
To: Bruce Evans <brde at optusnet.com.au>
Cc: Yuri <yuri at tsoft.com>, freebsd-gnats-submit at freebsd.org,
freebsd-bugs at freebsd.org
Subject: Re: misc/118160: unable to mount / rw while booting 7.0-BETA3
Date: Tue, 27 Nov 2007 22:36:28 -0800
Quoting Bruce Evans <brde at optusnet.com.au>:
> Using the 'c' partition is normally an error. Here it is a very large
> error. ad12s1b overlaps ad12s1c, so if swap on ad12s1b is actually
> used then it will normally clobber the file system on ad12s1c. It
> might be possible to make the clobbering harmless, e.g., by putting
> ad12s1b at the end of ad12s1c and not using all of ad12s1c for the
> file system, but this is harder to configure than a normal configuration
> and is supposed to be disallowed.
Having root mounted on ad12s1c is probably a result of my typo.
> This misbehaviour seems to be a result of the disallowment not being
> complete. Mounted file systems normally have exclusive write access
> to their device. However, for early root mounts, while the mount is
> only r/o, exclusive write access is given up so that fsck can work.
> There seems to be no exclusivity at all, so swapon on a different but
> overlapping device is granted write access. Then while swapon is on,
> it holds exclusive write access and r/w mounts of root are denied
> (correctly except for the wrong errno and other misleading things in
> the error message). Also, after the root mount becomes r/w, swapon
> fails (correctly except for the wrong errno).
Should this situation generate system log message, not only EPERM?
If it would have said: 'Attempt to mount already exclusively locked
partition' it would have been clear what the problem is right away.
So I would suggest such message to be added, otherwise this PR can be closed.
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