libceph: define CEPH_MSG_MAX_MIDDLE_LEN

This is probably unnecessary but the code read as if it were wrong
in read_partial_message().

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
diff --git a/include/linux/ceph/libceph.h b/include/linux/ceph/libceph.h
index 29818fc..5493d7b 100644
--- a/include/linux/ceph/libceph.h
+++ b/include/linux/ceph/libceph.h
@@ -66,6 +66,7 @@
 #define CEPH_OSD_IDLE_TTL_DEFAULT    60
 
 #define CEPH_MSG_MAX_FRONT_LEN	(16*1024*1024)
+#define CEPH_MSG_MAX_MIDDLE_LEN	(16*1024*1024)
 #define CEPH_MSG_MAX_DATA_LEN	(16*1024*1024)
 
 #define CEPH_AUTH_NAME_DEFAULT   "guest"