ceph: don't set WRITE_PENDING too early

prepare_write_connect() prepares a connect message, then sets
WRITE_PENDING on the connection.  Then *after* this, it calls
prepare_connect_authorizer(), which updates the content of the
connection buffer already queued for sending.  It's also possible it
will result in prepare_write_connect() returning -EAGAIN despite the
WRITE_PENDING big getting set.

Fix this by preparing the connect authorizer first, setting the
WRITE_PENDING bit only after that is done.

Partially addresses http://tracker.newdream.net/issues/2424

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>

net/ceph/messenger.c

@@ -697,6 +697,7 @@ static int prepare_write_connect(struct ceph_connection *con)
 {
 	unsigned global_seq = get_global_seq(con->msgr, 0);
 	int proto;
+	int ret;
 
 	switch (con->peer_name.type) {
 	case CEPH_ENTITY_TYPE_MON:
@@ -723,11 +724,14 @@ static int prepare_write_connect(struct ceph_connection *con)
 	con->out_connect.flags = 0;
 
 	ceph_con_out_kvec_add(con, sizeof (con->out_connect), &con->out_connect);
+	ret = prepare_connect_authorizer(con);
+	if (ret)
+		return ret;
 
 	con->out_more = 0;
 	set_bit(WRITE_PENDING, &con->state);
 
-	return prepare_connect_authorizer(con);
+	return 0;
 }
 
 /*