nfsd: split nfsd4_callback initialization and use

Split out initializing the nfs4_callback structure from using it.  For
the NULL callback this gets rid of tons of pointless re-initializations.

Note that I don't quite understand what protects us from running multiple
NULL callbacks at the same time, but at least this chance doesn't make
it worse..

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 03d9f4f..d97e200 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -743,11 +743,6 @@
 
 static struct workqueue_struct *callback_wq;
 
-static void do_probe_callback(struct nfs4_client *clp)
-{
-	return nfsd4_cb(&clp->cl_cb_null, clp, NFSPROC4_CLNT_CB_NULL);
-}
-
 /*
  * Poke the callback thread to process any updates to the callback
  * parameters, and send a null probe.
@@ -756,7 +751,7 @@
 {
 	clp->cl_cb_state = NFSD4_CB_UNKNOWN;
 	set_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_flags);
-	do_probe_callback(clp);
+	nfsd4_run_cb(&clp->cl_cb_null);
 }
 
 void nfsd4_probe_callback_sync(struct nfs4_client *clp)
@@ -912,7 +907,7 @@
 	 * instead, nfsd4_run_cb_null() will detect the killed
 	 * client, destroy the rpc client, and stop:
 	 */
-	do_probe_callback(clp);
+	nfsd4_run_cb(&clp->cl_cb_null);
 	flush_workqueue(callback_wq);
 }
 
@@ -1025,7 +1020,7 @@
 	nfsd4_run_callback_rpc(cb);
 }
 
-void nfsd4_cb(struct nfsd4_callback *cb, struct nfs4_client *clp,
+void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp,
 		enum nfsd4_cb_op op)
 {
 	cb->cb_clp = clp;
@@ -1038,6 +1033,9 @@
 		cb->cb_ops = &nfsd4_cb_recall_ops;
 	INIT_LIST_HEAD(&cb->cb_per_client);
 	cb->cb_done = true;
+}
 
+void nfsd4_run_cb(struct nfsd4_callback *cb)
+{
 	queue_work(callback_wq, &cb->cb_work);
 }