Re: panic: vput: negative ref cnt

From: Mark Powell <M.S.Powell_at_salford.ac.uk>
Date: Sun, 5 Apr 2009 12:15:04 +0100 (BST)
On Sun, 5 Apr 2009, Stefan Bethke wrote:

Stefan,
   Thanks for the input.

> Am 04.04.2009 um 13:55 schrieb Mark Powell:
>> My script takes a zfs snapshot, mounts the snapshot, backs it up using 
>> star, then umounts the snapshot. The panic seems to occur on the umount.
>
> This is a different panic from the one I was getting, but appears to occur 
> under the same circumstances.
>
> I managed to avoid the panic by keeping the snapshot until the next run of my 
> backup script, and not unmounting anything.

   Yeah, I got around it by avoiding the unmount.
   My script dates from 7-STABLE days, where a zfs bug caused the 
automounted snapdir e.g. .zfs/snapshot/star_L0_2009-04-04-16:57, to be 
missing a '..' entry. That prevented star from detecting that I was 
performing a true full backup.  Thus my script directly mounted the 
snapshot to get a proper fs with a '..' entry and unmounted it when 
finished.
   Now the included version of zfs in 8-CURRENT doesn't have that bug any 
longer. So I've reverted to backing up the automounted snapdir. 
Consequently as I don't perform a mount I don't have to unmount either, 
effectively working around the bug.

> See 
> <http://lists.freebsd.org/pipermail/freebsd-current/2009-February/003513.html>

Do you know if a PR has been submitted for this one?
   Cheers.

-- 
Mark Powell - UNIX System Administrator - The University of Salford
Information & Learning Services, Clifford Whitworth Building,
Salford University, Manchester, M5 4WT, UK.
Tel: +44 161 295 6843  Fax: +44 161 295 5888  www.pgp.com for PGP key
Received on Sun Apr 05 2009 - 09:15:09 UTC

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