Re: kern/37955: Kernel Panic NetBSD 4.0 blkfree

[David Holland <dholland-bugs%netbsd.org@localhost>]

On Wed, Mar 05, 2008 at 12:00:05PM +0000, Vincent van den Berg wrote:
 > From: Vincent van den Berg <vincent%mijnpostvak.in@localhost>
 > To: gnats-bugs%NetBSD.org@localhost
 > Subject: Re: kern/37955: Kernel Panic NetBSD 4.0 blkfree
 > Date: Wed, 05 Mar 2008 12:56:59 +0100
 > 
 >  It just happened again, with a clean file system while using rsnapshot! 
 >  I think this is a serious bug.

Just to check, when you say clean, you mean like this, right?
   # fsck -f /dev/rwd0f
   ** /dev/rwd0f
   ** File system is already clean
   ** Last mounted on /scratch
   ** Phase 1 - Check Blocks and Sizes
   ** Phase 2 - Check Pathnames
   ** Phase 3 - Check Connectivity
   ** Phase 4 - Check Reference Counts
   ** Phase 5 - Check Cyl groups
   1 files, 1 used, 253998 free (14 frags, 31748 blocks, 0.0% fragmentation)
   # 

That is, it fscks cleanly, rather than merely this:
   # fsck /dev/rwd0f
   ** /dev/rwd0f
   ** File system is clean; not checking
   # 

because the clean bit in the superblock only means the fs is correct
if there are no bugs in either the kernel or fsck. Which would be a
nice thing to be able to claim, but isn't true.

(And I believe if you mount a volume without fscking it and then
unmount it, it will subsequently purport to be clean, even though it
may in fact be nothing of the sort.)

-- 
David A. Holland
dholland%netbsd.org@localhost