In several sources of the "modules" module (i.e. vfs_audit.c, vfs_full_audit.c, vfs_extd_audit.c, vfs_cap.c SMB_VFS_NEXT_OPEN is used with 5 instead of 6 arguments as defined and there is at least one gcc version not forgiving and rejecting compilation.
Top-of-tree currently has the open operation defined as taking 5 arguments. I checked all the open operations in the various moduels and they are OK.