Re: Umount a filesystem fails, even if no proccesses are accessing it

[David Holland <dholland+netbsd%eecs.harvard.edu@localhost>]

On Fri, Jan 04, 2008 at 10:58:54PM +0100, Bernd Ernesti wrote:
 > > >  umount: /home/source: Device busy
 > 
 > [..]
 > 
 > > there are still handles open on /home/source.  "fstat -f /home/source"
 > > may reveal which processes which have them open.
 > 
 > I used fstat, but I can't remeber now if I used it with -f, where that flag
 > shouldn't make a difference since -f only narrows down the search to one
 > file system.
 > 
 > fstat didn't show any open file handles for /home/source

Unfortunately, fstat shows open files, and if the problem is a
refcounting bug on vnodes rather than open files, it is stale vnodes
that will be hanging around, and the results of fstat will be null or
even misleading.

Also unfortunately, refcounting bugs are notoriously hard to track
down.

There's probably an error case somwhere that's missing its vrele().

-- 
   - David A. Holland / dholland+netbsd%eecs.harvard.edu@localhost