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

[Kirill A. Shutemov]

On Fri, Jun 08, 2012 at 03:31:20PM -0700, Andrew Morton wrote:
> On Fri, 8 Jun 2012 23:27:34 +0100
> Al Viro <viro at 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?

Multiple inode caches? No.
Multiple caches with call_rcu() free? See btrfs or gfs2.

-- 
 Kirill A. Shutemov
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