Re: ufs_wapbl_rename

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

On Thu, Jul 14, 2011 at 09:01:00AM +0000, David Holland wrote:
 > New patch for wapbl_ufs_rename:
 > 
 >    http://www.eecs.harvard.edu/~dholland/tmp/netbsd/rename-candidate.diff
 > 
 > this is smaller and less directly intrusive than the old patch set,
 > but it has the same problem:
 > 
 > ufs_direnter: reached 4.2-only block, not supposed to happen
 > panic: kernel diagnostic assertion "vp->v_size == ip->i_size" failed: file 
 > "../../../../ufs/ufs/ufs_lookup.c", line 1460

Ok, I think this was caused when the rename to-parent (tdvp) was
rmdir'd during the wobbly vfs-level locking, and this wasn't being
adequately detected. The URL above has been updated with a new
candidate patch (still for ufs_wapbl_rename only) which I believe
works.

I will commit it later after an anita run if I don't find any more
problems.

Note that when pounding on rename I am occasionally seeing:

   panic: lockdebug_barrier: holding 1 shared locks

but I don't think this is anything I did, because vnode locks aren't
shared except in a few cases pertaining to getdents, which should be
entirely uninvolved. Also there appears to be no way whatsoever to
debug this; if anyone has suggestions please share.

Regardless things are much more stable with the patch than without so
I think I will commit anyway.

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