ceph: zero unused message header, footer fields

We shouldn't leak any prior memory contents to other parties.  And random
data, particularly in the 'version' field, can cause problems down the
line.
Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/messenger.c

@@ -2085,15 +2085,19 @@ struct ceph_msg *ceph_msg_new(int type, int front_len,
 	kref_init(&m->kref);
 	INIT_LIST_HEAD(&m->list_head);
 
+	m->hdr.tid = 0;
 	m->hdr.type = cpu_to_le16(type);
+	m->hdr.priority = cpu_to_le16(CEPH_MSG_PRIO_DEFAULT);
+	m->hdr.version = 0;
 	m->hdr.front_len = cpu_to_le32(front_len);
 	m->hdr.middle_len = 0;
 	m->hdr.data_len = cpu_to_le32(page_len);
 	m->hdr.data_off = cpu_to_le16(page_off);
-	m->hdr.priority = cpu_to_le16(CEPH_MSG_PRIO_DEFAULT);
+	m->hdr.reserved = 0;
 	m->footer.front_crc = 0;
 	m->footer.middle_crc = 0;
 	m->footer.data_crc = 0;
+	m->footer.flags = 0;
 	m->front_max = front_len;
 	m->front_is_vmalloc = false;
 	m->more_to_follow = false;