[RFC, PATCH] fs: push rcu_barrier() from deactivate_locked_super() to filesystems

[Linus Torvalds]

On Fri, Jun 8, 2012 at 3:00 PM, Kirill A. Shutemov
<kirill.shutemov at linux.intel.com> wrote:
>
> IIUC, moving rcu_barrier() up should help, but I can't say that I fully
> understand SLAB_DESTROY_BY_RCU semantics.

.. hmm. I think you may be right. Even if we do move it up, we
probably shouldn't use it.

We don't even want SLAB_DESTROY_BY_RCU, since we do the delayed RCU
free for other reasons anyway, so it would duplicate the RCU delaying
and cause problems. I forgot about that little complication.

We could have a separate "RCU_BARRIER_ON_DESTROY" thing, but that's
just silly too.

Maybe your patch is the right thing.

            Linus