Date: Wed, 14 Oct 2009 15:35:26 +0200 (CEST) From: Alexander Best <alexbestms@math.uni-muenster.de> To: Andriy Gapon <avg@icyb.net.ua> Cc: freebsd-current@FreeBSD.org Subject: Re: panic when mounting device >= 2 times Message-ID: <permail-20091014133526f0889e840000348b-a_best01@message-id.uni-muenster.de> In-Reply-To: <4AD5BD00.4050700@icyb.net.ua>
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Andriy Gapon schrieb am 2009-10-14: > on 14/10/2009 14:21 Alexander Best said the following: > > could somebody have a look at this PR please: > > http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/108968 > > this still exists in -CURRENT. > This is because of serious and long-standing brokenness (probably > from time of > introduction of GEOM) in g_vfs_open/g_vfs_close. > The essence: > 1. we allow multiple concurrent read-only mounts of a device > 2. but even a read-only mount mangles bufobj of device vnode > 3. Bug! > Trivial fix with POLA violation - prohibit concurrent RO mounts. > Non-trivial fix - _somehow_ avoid changing or depending on device > vnode bufobj. > See this for even more evil example of this problem: > http://lists.freebsd.org/pipermail/freebsd-fs/2009-February/005676.html thanks a lot for the hint. unfortunately i'm not a programmer and thus won't be able to help with this problem. :-( cheers. alex
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