Date: Sat, 7 Jun 2003 11:13:58 +1000 (EST) From: Bruce Evans <bde@zeta.org.au> To: Per Kristian Hove <Per.Hove@math.ntnu.no> Cc: freebsd-current@freebsd.org Subject: Re: geom_vol_ffs problems Message-ID: <20030607105610.R36915@gamplex.bde.org> In-Reply-To: <Pine.GSO.4.52.0306061813000.17732@abel.math.ntnu.no> References: <Pine.GSO.4.52.0306041435020.6491@abel.math.ntnu.no> <Pine.GSO.4.52.0306061813000.17732@abel.math.ntnu.no>
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On Fri, 6 Jun 2003, Per Kristian Hove wrote: > I've nailed it down to this: geom_vol_ffs assumes that a file system > is able to fill the partition completely. That's not a valid > assumption, since the file system size is a multiple of the file > system block size (in my case 16k bytes = 32 blocks), and the > partition size is/should be a multiple of the sectors/cylinder count > (in my case 1008). > > For this assumption to be valid, the sectors/cylinder count would have > to be a multiple of the file system block size (measured in blocks), > and there's no guarantee that that's the case. > > In my case, the size of the filesystem on ad0s3f (the one that does > not appear in /dev/vol/) is one block less than the size of ad0s3f > itself, so geom_vol_ffs refuses to create a provider for it (lines 96 > and 102 in geom_vol_ffs.c): > > if (fs->fs_old_size * fs->fs_fsize != > (int32_t) pp->mediasize) { > g_free(fs); > continue; > } Other bugs in this code include overflow for file systems larger than a whole 2GB, a bogus cast to give the correct result if the overflow is benign and the actual sizes don't differ by a multiple of 4G, and a style bug in the bogus cast (casts and sizeofs are not followed by a space). Bruce
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