NFS: Clean up nfs4_find_state_owners_locked()

There's no longer a need to check the so_server field in the state
owner, because nowadays the RB tree we search for state owners
contains owners for that only server.

Make nfs4_find_state_owners_locked() use the same tree searching logic
as nfs4_insert_state_owner_locked().

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4state.c

@@ -377,31 +377,22 @@ nfs4_find_state_owner_locked(struct nfs_server *server, struct rpc_cred *cred)
 {
 	struct rb_node **p = &server->state_owners.rb_node,
 		       *parent = NULL;
-	struct nfs4_state_owner *sp, *res = NULL;
+	struct nfs4_state_owner *sp;
 
 	while (*p != NULL) {
 		parent = *p;
 		sp = rb_entry(parent, struct nfs4_state_owner, so_server_node);
 
-		if (server < sp->so_server) {
-			p = &parent->rb_left;
-			continue;
-		}
-		if (server > sp->so_server) {
-			p = &parent->rb_right;
-			continue;
-		}
 		if (cred < sp->so_cred)
 			p = &parent->rb_left;
 		else if (cred > sp->so_cred)
 			p = &parent->rb_right;
 		else {
 			atomic_inc(&sp->so_count);
-			res = sp;
-			break;
+			return sp;
 		}
 	}
-	return res;
+	return NULL;
 }
 
 static struct nfs4_state_owner *