ocfs2_dlm: disallow a domain join if node maps mismatch

There is a small window where a joining node may not see the node(s) that
just died but are still part of the domain. To fix this, we must disallow
join requests if the joining node has a different node map.

A new field node_map is added to dlm_query_join_request to send the current
nodes nodemap along with join request. On the receiving end the nodes that
are part of the cluster verifies if this new node sees all the nodes that
are still part of the cluster. They disallow the join if the maps mismatch.

Signed-off-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/ocfs2/dlm/dlmcommon.h b/fs/ocfs2/dlm/dlmcommon.h
index 2f4f5d4edb07..e90b92f9ece1 100644
--- a/fs/ocfs2/dlm/dlmcommon.h
+++ b/fs/ocfs2/dlm/dlmcommon.h
@@ -625,12 +625,16 @@ struct dlm_begin_reco
 };
 
 
+#define BITS_PER_BYTE 8
+#define BITS_TO_BYTES(bits) (((bits)+BITS_PER_BYTE-1)/BITS_PER_BYTE)
+
 struct dlm_query_join_request
 {
 	u8 node_idx;
 	u8 pad1[2];
 	u8 name_len;
 	u8 domain[O2NM_MAX_NAME_LEN];
+	u8 node_map[BITS_TO_BYTES(O2NM_MAX_NODES)];
 };
 
 struct dlm_assert_joined