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Re: kern/50070: fsck OK but mount: incorrect super block
The following reply was made to PR kern/50070; it has been noted by GNATS.
From: "J. Hannken-Illjes" <hannken%eis.cs.tu-bs.de@localhost>
To: Maxime Villard <max%M00nBSD.net@localhost>
Cc: Martin Husemann <martin%duskware.de@localhost>,
Subject: Re: kern/50070: fsck OK but mount: incorrect super block
Date: Thu, 22 Oct 2015 12:02:35 +0200
On 22 Oct 2015, at 10:24, Maxime Villard <max%M00nBSD.net@localhost> wrote:
> Le 22/10/2015 09:37, Martin Husemann a =E9crit :
>> J. Hannken-Illjes wrote:
>>> This cgsize test from ffs_superblock_validate() is wrong. Newfs =
>>> fs_cgsize to fragment size:
>>> sblock.fs_cgsize =3D ffs_fragroundup(&sblock, CGSIZE(&sblock));
> And so does ffs_superblock_validate(), doesn't it? Can you elaborate
> a bit?
>>> All we should test here is
>>> fs->fs_cgsize >=3D sizeof(struct cg)
>>> fs->fs_cgsize <=3D fs->fs_bsize
> The only bug I can see currently in ffs_vfsops.c is that the =
> is validated before ffs_oldfscompat_read() is called, which means that
> FFSv1+!FS_FLAGS_UPDATED disks may not mount correctly. This is not the
> case in that PR, since "fslevel 4" means FFSv1+FS_FLAGS_UPDATED.
As already noted in this PR the first bug is to assume CGSIZE() returns
an exact value. It is just a guess, newfs(8) uses it as a starting
point and reduces it to be less than fs_bsize.
We will read cylinder groups with size fs_cgsize so this value has to
be greater than sizeof(cg) and less or equal fs_bsize.
If we want to check the cylinder groups, we have to check the pointers
from struct cg against fs_cgsize and we have to do this check on every
call to cg_chkmagic().
J. Hannken-Illjes - hannken%eis.cs.tu-bs.de@localhost - TU Braunschweig (Germany)
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