- Move SETKLOC and CLEARKLOCK macros into uion.h.

- Set UN_ULOCK in union_lock() when UN_KLOCK is set.  Caller expects
  that vnode is locked correctly, and may call another function which
  expects locked vnode and may unlock the vnode.
- Do not assume the behavior of inside functions in FreeBSD's
  vfs_suber.c is same as 4.4BSD-Lite2.  Vnode may be locked in
  vget() even though flag is zero.  (Locked vnode is, of course,
  unlocked before returning from vget.)

3 files changed, 33 insertions, 10 deletions

diff --git a/sys/miscfs/union/union.h b/sys/miscfs/union/union.h
index 03e7033..f3bbb89 100644
--- a/sys/miscfs/union/union.h
+++ b/sys/miscfs/union/union.h
@@ -35,7 +35,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)union.h	8.9 (Berkeley) 12/10/94
- * $Id: union.h,v 1.8 1997/02/22 09:40:40 peter Exp $
+ * $Id: union.h,v 1.9 1997/11/18 15:07:34 phk Exp $
  */
 
 struct union_args {
@@ -94,6 +94,9 @@ struct union_node {
 #define UN_KLOCK	0x08		/* Keep upper node locked on vput */
 #define UN_CACHED	0x10		/* In union cache */
 
+#define	SETKLOCK(un)	(un)->un_flags |= UN_KLOCK
+#define	CLEARKLOCK(un)	(un)->un_flags &= ~UN_KLOCK
+
 extern int union_allocvp __P((struct vnode **, struct mount *,
 				struct vnode *, struct vnode *,
 				struct componentname *, struct vnode *,
diff --git a/sys/miscfs/union/union_subr.c b/sys/miscfs/union/union_subr.c
index 3b17f9c..87ba491 100644
--- a/sys/miscfs/union/union_subr.c
+++ b/sys/miscfs/union/union_subr.c
@@ -35,7 +35,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)union_subr.c	8.20 (Berkeley) 5/20/95
- * $Id: union_subr.c,v 1.22 1997/11/18 15:07:35 phk Exp $
+ * $Id: union_subr.c,v 1.23 1997/12/27 02:56:26 bde Exp $
  */
 
 #include <sys/param.h>
@@ -307,6 +307,7 @@ union_allocvp(vpp, mp, undvp, dvp, cnp, uppervp, lowervp, docache)
 	int hash;
 	int vflag;
 	int try;
+	int	klocked;
 
 	if (uppervp == NULLVP && lowervp == NULLVP)
 		panic("union: unidentifiable allocation");
@@ -362,11 +363,27 @@ loop:
 			    (un->un_uppervp == uppervp ||
 			     un->un_uppervp == NULLVP) &&
 			    (UNIONTOV(un)->v_mount == mp)) {
+				/*
+				 * Do not assume that vget() does not
+				 * lock the vnode even though flags
+				 * argument is 0.
+				 */
+				if ((un->un_uppervp != NULLVP) &&
+					((un->un_flags & UN_KLOCK) == 0)) {
+					SETKLOCK(un);
+					klocked = 1;
+				} else {
+					klocked = 0;
+				}
 				if (vget(UNIONTOV(un), 0,
 				    cnp ? cnp->cn_proc : NULL)) {
+					if (klocked)
+						CLEARKLOCK(un);
 					union_list_unlock(hash);
 					goto loop;
 				}
+				if (klocked)
+					CLEARKLOCK(un);
 				break;
 			}
 		}
diff --git a/sys/miscfs/union/union_vnops.c b/sys/miscfs/union/union_vnops.c
index 1c6b124..d856da2 100644
--- a/sys/miscfs/union/union_vnops.c
+++ b/sys/miscfs/union/union_vnops.c
@@ -35,7 +35,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)union_vnops.c	8.32 (Berkeley) 6/23/95
- * $Id: union_vnops.c,v 1.47 1998/01/18 07:56:41 kato Exp $
+ * $Id: union_vnops.c,v 1.48 1998/01/18 08:17:48 kato Exp $
  */
 
 #include <sys/param.h>
@@ -58,9 +58,6 @@
 	} \
 }
 
-#define	SETKLOCK(un)	(un)->un_flags |= UN_KLOCK
-#define	CLEARKLOCK(un)	(un)->un_flags &= ~UN_KLOCK
-
 static int	union_abortop __P((struct vop_abortop_args *ap));
 static int	union_access __P((struct vop_access_args *ap));
 static int	union_advlock __P((struct vop_advlock_args *ap));
@@ -1548,11 +1545,13 @@ start:
 	un = VTOUNION(vp);
 
 	if (un->un_uppervp != NULLVP) {
-		if (((un->un_flags & (UN_ULOCK | UN_KLOCK)) == 0) &&
+		if (((un->un_flags & UN_ULOCK) == 0) &&
 		    (vp->v_usecount != 0)) {
-			error = vn_lock(un->un_uppervp, flags, p);
-			if (error)
-				return (error);
+			if ((un->un_flags & UN_KLOCK) == 0) {
+				error = vn_lock(un->un_uppervp, flags, p);
+				if (error)
+					return (error);
+			}
 			un->un_flags |= UN_ULOCK;
 		}
 	}
@@ -1590,6 +1589,10 @@ start:
  *
  * If UN_KLOCK isn't set, then the upper vnode is unlocked here.
  */
+/*
+ * FreeBSD:  Do not cleark UN_KLOCK flag.  UN_KLOCK flag is tested
+ * in union_lock().
+ */
 static int
 union_unlock(ap)
 	struct vop_unlock_args /* {