dlm: improve how bast mode handling

The lkb bastmode value is set in the context of processing the
lock, and read by the dlm_astd thread.  Because it's accessed
in these two separate contexts, the writing/reading ought to
be done under a lock.  This is simple to do by setting it and
reading it when the lkb is added to and removed from dlm_astd's
callback list which is properly locked.

Signed-off-by: David Teigland <teigland@redhat.com>

fs/dlm/user.h

@@ -9,7 +9,7 @@
 #ifndef __USER_DOT_H__
 #define __USER_DOT_H__
 
-void dlm_user_add_ast(struct dlm_lkb *lkb, int type);
+void dlm_user_add_ast(struct dlm_lkb *lkb, int type, int bastmode);
 int dlm_user_init(void);
 void dlm_user_exit(void);
 int dlm_device_deregister(struct dlm_ls *ls);