[Cluster-devel] [PATCH dlm/next 1/5] fs: dlm: add comment about lkb IFL flags

[Alexander Aring <aahringo@redhat.com>]

This patch adds comments about the difference between the lower 2 bytes
of lkb flags and the 2 upper bytes of the lkb IFL flags. In short the
upper 2 bytes will be handled as internal flags whereas the lower 2
bytes are part of the DLM protocol and are used to exchange messages.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/dlm_internal.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index c03388a3875c..151f98fc3f22 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -207,6 +207,13 @@ struct dlm_args {
 #define DLM_IFL_TIMEOUT_CANCEL	0x00800000
 #define DLM_IFL_DEADLOCK_CANCEL	0x01000000
 #define DLM_IFL_STUB_MS		0x02000000 /* magic number for m_flags */
+/* least significant 2 bytes are message changed, they are full transmitted
+ * but at receive side only the 2 bytes LSB will be set.
+ *
+ * Even wireshark dlm dissector does only evaluate the lower bytes and note
+ * that they may not be used on transceiver side, we assume the higher bytes
+ * are for internal use or reserved so long they are parsed on receiver side.
+ */
 #define DLM_IFL_USER		0x00000001
 #define DLM_IFL_ORPHAN		0x00000002
 
-- 
2.31.1