From: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC, PATCH, RESEND] fs: push rcu_barrier() from
 deactivate_locked_super() to filesystems
Date: Fri, 8 Jun 2012 15:31:20 -0700
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Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
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To: Al Viro <viro@ZenIV.linux.org.uk>
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On Fri, 8 Jun 2012 23:27:34 +0100
Al Viro <viro@ZenIV.linux.org.uk> wrote:

> On Fri, Jun 08, 2012 at 03:25:50PM -0700, Andrew Morton wrote:
> 
> > A neater implementation might be to add a kmem_cache* argument to
> > unregister_filesystem().  If that is non-NULL, unregister_filesystem()
> > does the rcu_barrier() and destroys the cache.  That way we get to
> > delete (rather than add) a bunch of code from all filesystems and new
> > and out-of-tree filesystems cannot forget to perform the rcu_barrier().
> 
> There's often enough more than one cache, so that one is no-go.

kmem_cache** ;)

Which filesystems have multiple inode caches?