Date: Tue, 27 Nov 2007 22:36:28 -0800 From: Yuri <yuri@rawbw.com> To: Bruce Evans <brde@optusnet.com.au> Cc: Yuri <yuri@tsoft.com>, freebsd-gnats-submit@freebsd.org, freebsd-bugs@freebsd.org Subject: Re: misc/118160: unable to mount / rw while booting 7.0-BETA3 Message-ID: <1196231788.474d0c6c67e9b@webmail.rawbw.com> In-Reply-To: <20071128144615.T745@besplex.bde.org> References: <200711210234.lAL2Y7cU041129@www.freebsd.org> <20071121170349.X81263@delplex.bde.org> <1196219512.474cdc78837c1@webmail.rawbw.com> <20071128144615.T745@besplex.bde.org>
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Quoting Bruce Evans <brde@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. Yuri
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