[pnfs] [PATCH] check that the owner is unlocking

[J. Bruce Fields]

On Fri, May 16, 2008 at 10:12:33AM -0700, Marc Eshel wrote:
> "J. Bruce Fields" <bfields at fieldses.org> wrote on 05/16/2008 09:59:35 AM:
> > Right, but I don't understand why the client_mutex_owner is needed, when
> > the struct mutex already has an owner field, and already uses it to do
> > the above check for us; see include/linux/mutex.h.  Looks like you need
> > CONFIG_DEBUG_MUTEXES defined (under Kernel Hacking->"Mutex debugging:
> > basic checks").
> 
> I am not sure if there is better way to implement 
> nfs4_lock_state_nested(),

Again, just look at the definition of struct mutex in
include/linux/mutex.h.  You can change the

	if (client_mutex_owner == current_thread_info())

to

	if (client_mutex.owner == current_thread_info())

and make NFS_V4_1 depend on CONFIG_DEBUG_MUTEXES.

In the longer term, I think we should work out how to get rid of
nfs4_lock_state_nested().

--b.

> I did not this routine but as long as this 
> routine is there it depend on that owner field.
> Marc.
>  
> > 
> > --b.
> > 
> > > so if some thread unlocks 
> > > a lock that it doesn't own it will reset the real owner to NULL which 
> will 
> > > confuse functions like nfs4_lock_state_nested().
>