ceph: have get_authorizer methods return pointers

Have the get_authorizer auth_client method return a ceph_auth
pointer rather than an integer, pointer-encoding any returned
error value.  This is to pave the way for making use of the
returned value in an upcoming patch.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index e0532d5..ac27a2c 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -658,7 +658,7 @@
 	void *auth_buf;
 	int auth_len;
 	int auth_protocol;
-	int ret;
+	struct ceph_auth_handshake *auth;
 
 	if (!con->ops->get_authorizer) {
 		con->out_connect.authorizer_protocol = CEPH_AUTH_UNKNOWN;
@@ -674,13 +674,13 @@
 	auth_buf = NULL;
 	auth_len = 0;
 	auth_protocol = CEPH_AUTH_UNKNOWN;
-	ret = con->ops->get_authorizer(con, &auth_buf, &auth_len,
+	auth = con->ops->get_authorizer(con, &auth_buf, &auth_len,
 				&auth_protocol, &con->auth_reply_buf,
 				&con->auth_reply_buf_len, con->auth_retry);
 	mutex_lock(&con->mutex);
 
-	if (ret)
-		return ret;
+	if (IS_ERR(auth))
+		return PTR_ERR(auth);
 
 	if (test_bit(CLOSED, &con->state) || test_bit(OPENING, &con->state))
 		return -EAGAIN;