nfsd: warn about impending removal of nfsdcld upcall

Let's shoot for removing the nfsdcld upcall in 3.10. Most likely,
no one is actually using it so I don't expect this warning to
fire often (except maybe on misconfigured systems).
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4recover.c

@@ -1166,6 +1166,9 @@ nfsd4_client_tracking_init(struct net *net)
 
 	/* Finally, try to use nfsdcld */
 	client_tracking_ops = &nfsd4_cld_tracking_ops;
+	printk(KERN_WARNING "NFSD: the nfsdcld client tracking upcall will be "
+			"removed in 3.10. Please transition to using "
+			"nfsdcltrack.\n");
 do_init:
 	status = client_tracking_ops->init(net);
 	if (status) {