[DLM] reject replies to old requests

When recoveries are aborted by other recoveries we can get replies to
status or names requests that we've given up on.  This can cause problems
if we're making another request and receive an old reply.  Add a sequence
number to status/names requests and reject replies that don't match.  A
field already exists for the seq number that's used in other message
types.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index ec7e4011..da75099 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -468,6 +468,7 @@
 	struct mutex		ls_requestqueue_mutex;
 	char			*ls_recover_buf;
 	int			ls_recover_nodeid; /* for debugging */
+	uint64_t		ls_rcom_seq;
 	struct list_head	ls_recover_list;
 	spinlock_t		ls_recover_list_lock;
 	int			ls_recover_list_count;