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 <[e-mail]>

fs/dlm/ast.c

···
 *******************************************************************************
 **
 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
-**  Copyright (C) 2004-2005 Red Hat, Inc.  All rights reserved.
+**  Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
 **
 **  This copyrighted material is made available to anyone wishing to use,
 **  modify, copy, or redistribute it subject to the terms and conditions
···
 	spin_unlock(&ast_queue_lock);
 }
 
-void dlm_add_ast(struct dlm_lkb *lkb, int type)
+void dlm_add_ast(struct dlm_lkb *lkb, int type, int bastmode)
 {
 	if (lkb->lkb_flags & DLM_IFL_USER) {
-		dlm_user_add_ast(lkb, type);
+		dlm_user_add_ast(lkb, type, bastmode);
 		return;
 	}
 
···
 		list_add_tail(&lkb->lkb_astqueue, &ast_queue);
 	}
 	lkb->lkb_ast_type |= type;
+	if (bastmode)
+		lkb->lkb_bastmode = bastmode;
 	spin_unlock(&ast_queue_lock);
 
 	set_bit(WAKE_ASTS, &astd_wakeflags);
···
 	struct dlm_lkb *lkb;
 	void (*cast) (void *astparam);
 	void (*bast) (void *astparam, int mode);
-	int type = 0, found, bmode;
+	int type = 0, found, bastmode;
 
 	for (;;) {
 		found = 0;
···
 			list_del(&lkb->lkb_astqueue);
 			type = lkb->lkb_ast_type;
 			lkb->lkb_ast_type = 0;
+			bastmode = lkb->lkb_bastmode;
 			found = 1;
 			break;
 		}
···
 
 		cast = lkb->lkb_astfn;
 		bast = lkb->lkb_bastfn;
-		bmode = lkb->lkb_bastmode;
 
 		if ((type & AST_COMP) && cast)
 			cast(lkb->lkb_astparam);
 
 		if ((type & AST_BAST) && bast)
-			bast(lkb->lkb_astparam, bmode);
+			bast(lkb->lkb_astparam, bastmode);
 
 		/* this removes the reference added by dlm_add_ast
 		   and may result in the lkb being freed */

fs/dlm/ast.h

···
 /******************************************************************************
 *******************************************************************************
 **
-**  Copyright (C) 2005 Red Hat, Inc.  All rights reserved.
+**  Copyright (C) 2005-2008 Red Hat, Inc.  All rights reserved.
 **
 **  This copyrighted material is made available to anyone wishing to use,
 **  modify, copy, or redistribute it subject to the terms and conditions
···
 #ifndef __ASTD_DOT_H__
 #define __ASTD_DOT_H__
 
-void dlm_add_ast(struct dlm_lkb *lkb, int type);
+void dlm_add_ast(struct dlm_lkb *lkb, int type, int bastmode);
 void dlm_del_ast(struct dlm_lkb *lkb);
 
 void dlm_astd_wake(void);

fs/dlm/lock.c

···
 	lkb->lkb_lksb->sb_status = rv;
 	lkb->lkb_lksb->sb_flags = lkb->lkb_sbflags;
 
-	dlm_add_ast(lkb, AST_COMP);
+	dlm_add_ast(lkb, AST_COMP, 0);
 }
 
 static inline void queue_cast_overlap(struct dlm_rsb *r, struct dlm_lkb *lkb)
···
 {
 	if (is_master_copy(lkb))
 		send_bast(r, lkb, rqmode);
-	else {
-		lkb->lkb_bastmode = rqmode;
-		dlm_add_ast(lkb, AST_BAST);
-	}
+	else
+		dlm_add_ast(lkb, AST_BAST, rqmode);
 }
 
 /*

fs/dlm/user.c

···
 /* we could possibly check if the cancel of an orphan has resulted in the lkb
    being removed and then remove that lkb from the orphans list and free it */
 
-void dlm_user_add_ast(struct dlm_lkb *lkb, int type)
+void dlm_user_add_ast(struct dlm_lkb *lkb, int type, int bastmode)
 {
 	struct dlm_ls *ls;
 	struct dlm_user_args *ua;
···
 
 	ast_type = lkb->lkb_ast_type;
 	lkb->lkb_ast_type |= type;
+	if (bastmode)
+		lkb->lkb_bastmode = bastmode;
 
 	if (!ast_type) {
 		kref_get(&lkb->lkb_ref);

fs/dlm/user.h

···
 #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);