"panic: snapblkfree: inconsistent block type" on FreeBSD 9.0 RELEASE

[Jose Garcia Juanino]

El lunes 04 de junio a las 14:07:58 CEST, Ronald Klop escribió:
> On Sun, 03 Jun 2012 20:08:07 +0200, José García Juanino  
> <jjuanino at gmail.com> wrote:
> 
> > On 3 June 2012 14:16, José García Juanino <jjuanino at gmail.com> wrote:
> >> Hi,
> >>
> >> I am getting a lot of "snapblkfree: inconsistent block type" panics on
> >> my FreeBSD 9.0-RELEASE. My file systems have not any inconsistencies,
> >> I am checked them with fsck. But I have some snapshots with softupdate
> >> inconsistencies  (fsck_ffs /path/to/snapshot), and I suspect that may
> >> be the cause of the panics. I have several questions:
> >>
> >> 1- Snapshots with fsck inconsistencies might be the cause of my panics?
> >> 2- Should I remove any of such "corrupt" snapshots?
> >>
> >> If someone is interested, I can provide a full backtrace. Kernel is
> >> GENERIC, with no tweaks. File system are been created with normal
> >> "newfs -U". No special setting is using.
> >
> > I have three full core dumps:
> >
> > http://www.mipaginapersonal.movistar.es/web3/jjuanino/core.txt.1
> > http://www.mipaginapersonal.movistar.es/web3/jjuanino/core.txt.2
> > http://www.mipaginapersonal.movistar.es/web3/jjuanino/core.txt.3
> >
> > The relevant code is, in the three examples:
> >
> > #3  0xffffffff80a40124 in ffs_snapblkfree (fs=0xfffffe0002deb000,
> > devvp=Variable "devvp" is not available.
> > )
> >     at /usr/src/sys/ufs/ffs/ffs_snapshot.c:1799
> >
> > Regards
> 
> I don't know about the internals of FFS, but I know there were some fixes  
> to FFS + snapshots ( + journal (SUJ) ??) after 9.0-RELEASE. So maybe you  
> can test updating to and running with 9-STABLE.

Thanks for your reply. I cannot upgrade to 9-STABLE; it is a production
environment and only can run -RELEASE. In the other hand, I removed the
unclean snapshots (checked with fsck_ffs), but unfortunately did not
help and I got a new "snapblkfree: inconsistent block type" panic a few
hours later. At this moment, the overall of filesystems and snapshots
were clean (checked again with fsck).

When the system started up again, I decided remove all the snapshots,
but while I am doing this work, the computer again raised a new panic:
"ffs_blkfree_cg: freeing free block". Related this panic, I found this
post on freebsd-current:

http://lists.freebsd.org/pipermail/freebsd-current/2011-October/028860.html

I am almost sure I have not hardware failures. Indeed, after that panic,
I definitively removed all the remaining snapshots, and did a new fsck on
the filesystems. The system now goes smoothly, and the computer does not
panic anymore.

My advices, after this experiences: never keep snapshots (clean or
unclean) if your filesystem was not clean at some previous stage. The
overall of panics I have suffered are related with a previous dirty
mounted filesystem and several taken snapshots IMHO.

Regards, and excuse me if my english is not clear enough.
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