Re: [PATCH] vfs: Speed up deactivate_super for non-modularfilesystems

[Paul E. McKenney]

On Mon, May 07, 2012 at 11:17:06PM +0100, Al Viro wrote:
> On Mon, May 07, 2012 at 02:51:08PM -0700, Eric W. Biederman wrote:
> 
> > /proc and similar non-modular filesystems do not need a rcu_barrier
> > in deactivate_locked_super.  Being non-modular there is no danger
> > of the rcu callback running after the module is unloaded.
> 
> There's more than just a module unload there, though - actual freeing
> struct super_block also happens past that rcu_barrier()...

Is there anything in there for which synchronous operation is required?
If not, one approach would be to drop the rcu_barrier() calls to a
workqueue or something similar.

							Thanx, Paul

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