RPC: stops the release_pipe() funtion from being called twice

 This patch stops the release_pipe() funtion from being called
 twice by invalidating the ops pointer in the rpc_inode
 when rpc_pipe_release() is called.

 Signed-off-by: Steve Dickson <steved@redhat.com>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c
index ded6c63..649d609 100644
--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -177,6 +177,8 @@
 		__rpc_purge_upcall(inode, -EPIPE);
 	if (rpci->ops->release_pipe)
 		rpci->ops->release_pipe(inode);
+	if (!rpci->nreaders && !rpci->nwriters)
+		rpci->ops = NULL;
 out:
 	up(&inode->i_sem);
 	return 0;