--- //depot/vendor/freebsd/src/sys/kern/vfs_bio.c	2008/03/22 09:16:15
+++ //depot/user/attilio/attilio_schedlock/kern/vfs_bio.c	2008/03/28 01:22:10
@@ -544,7 +544,6 @@
 		bp->b_qindex = QUEUE_EMPTY;
 		bp->b_vflags = 0;
 		bp->b_xflags = 0;
-		bp->b_waiters = 0;
 		LIST_INIT(&bp->b_dep);
 		BUF_LOCKINIT(bp);
 		TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
@@ -1183,7 +1182,7 @@
 			if (bp->b_bufsize)
 				allocbuf(bp, 0);
 			if (bp->b_vp)
-				(void) brelvp(bp);
+				brelvp(bp);
 		}
 	}
 
@@ -1324,7 +1323,7 @@
 		if (bp->b_bufsize != 0)
 			allocbuf(bp, 0);
 		if (bp->b_vp != NULL)
-			(void) brelvp(bp);
+			brelvp(bp);
 	}
 			
 	if (BUF_LOCKRECURSED(bp)) {
@@ -1388,7 +1387,7 @@
 		if (bp->b_flags & B_DELWRI)
 			bundirty(bp);
 		if (bp->b_vp)
-			(void) brelvp(bp);
+			brelvp(bp);
 	}
 
 	/*
@@ -1555,7 +1554,7 @@
 	bp->b_npages = 0;
 	bp->b_flags &= ~B_VMIO;
 	if (bp->b_vp)
-		(void) brelvp(bp);
+		brelvp(bp);
 }
 
 /*
@@ -1693,7 +1692,6 @@
 	struct buf *nbp;
 	int defrag = 0;
 	int nqindex;
-	int waiters = 0;
 	static int flushingbufs;
 
 	/*
@@ -1832,7 +1830,7 @@
 				vfs_vmio_release(bp);
 			}
 			if (bp->b_vp)
-				waiters = brelvp(bp);
+				brelvp(bp);
 		}
 
 		/*
@@ -1901,7 +1899,7 @@
 		 * Notify any waiters for the buffer lock about
 		 * identity change by freeing the buffer.
 		 */
-		if (qindex == QUEUE_CLEAN && waiters > 0) {
+		if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) {
 			bp->b_flags |= B_INVAL;
 			bfreekva(bp);
 			brelse(bp);
--- //depot/vendor/freebsd/src/sys/kern/vfs_subr.c	2008/03/24 04:26:30
+++ //depot/user/attilio/attilio_schedlock/kern/vfs_subr.c	2008/03/28 01:22:10
@@ -1527,12 +1527,11 @@
 /*
  * Disassociate a buffer from a vnode.
  */
-int
+void
 brelvp(struct buf *bp)
 {
 	struct bufobj *bo;
 	struct vnode *vp;
-	int waiters;
 
 	CTR3(KTR_BUF, "brelvp(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
 	KASSERT(bp->b_vp != NULL, ("brelvp: NULL"));
@@ -1557,11 +1556,8 @@
 	bp->b_flags &= ~B_NEEDSGIANT;
 	bp->b_vp = NULL;
 	bp->b_bufobj = NULL;
-	waiters = bp->b_waiters;
 	BO_UNLOCK(bo);
 	vdrop(vp);
-
-	return (waiters);
 }
 
 /*
--- //depot/vendor/freebsd/src/sys/sys/buf.h	2008/03/28 00:17:25
+++ //depot/user/attilio/attilio_schedlock/sys/buf.h	2008/03/28 01:24:06
@@ -139,7 +139,6 @@
 	void	*b_fsprivate2;
 	void	*b_fsprivate3;
 	int	b_pin_count;
-	int	b_waiters;		/* (V) waiters counter */
 };
 
 #define b_object	b_bufobj->bo_object
@@ -267,38 +266,18 @@
  *
  * Get a lock sleeping non-interruptably until it becomes available.
  */
-static __inline int
-_BUF_LOCK(struct buf *bp, int locktype, struct mtx *interlock, char *file,
-    int line)
-{
-	int res;
+#define	BUF_LOCK(bp, locktype, interlock)				\
+	_lockmgr_args(&(bp)->b_lock, (locktype), (interlock),		\
+	    LK_WMESG_DEFAULT, LK_PRIO_DEFAULT, LK_TIMO_DEFAULT,		\
+	    LOCK_FILE, LOCK_LINE)
 
-	if (locktype & LK_INTERLOCK)
-		bp->b_waiters++;
-	res = _lockmgr_args(&bp->b_lock, locktype, interlock, LK_WMESG_DEFAULT,
-	    LK_PRIO_DEFAULT, LK_TIMO_DEFAULT, file, line);
-	if (locktype & LK_INTERLOCK)
-		bp->b_waiters--;
-	return (res);
-}
-
 /*
  * Get a lock sleeping with specified interruptably and timeout.
  */
-static __inline int
-_BUF_TIMELOCK(struct buf *bp, int locktype, struct mtx *interlock,
-    const char *wmesg, int catch, int timo, char *file, int line)
-{
-	int res;
-
-	if (locktype & LK_INTERLOCK)
-		bp->b_waiters++;
-	res = _lockmgr_args(&bp->b_lock, locktype | LK_TIMELOCK, interlock,
-	    wmesg, (PRIBIO + 4) | catch, timo, file, line);
-	if (locktype & LK_INTERLOCK)
-		bp->b_waiters--;
-	return (res);
-}
+#define	BUF_TIMELOCK(bp, locktype, interlock, wmesg, catch, timo)	\
+	_lockmgr_args(&(bp)->b_lock, (locktype) | LK_TIMELOCK,		\
+	    (interlock), (wmesg), (PRIBIO + 4) | (catch), (timo),	\
+	    LOCK_FILE, LOCK_LINE)
 
 /*
  * Release a lock. Only the acquiring process may free the lock unless
@@ -331,15 +310,6 @@
 	lockdestroy(&(bp)->b_lock)
 
 /*
- * Use macro wrappers in order to exploit consumers tracking.
- */
-#define	BUF_LOCK(bp, locktype, interlock)				\
-	_BUF_LOCK((bp), (locktype), (interlock), LOCK_FILE, LOCK_LINE)
-#define	BUF_TIMELOCK(bp, locktype, interlock, wmesg, catch, timo)	\
-	_BUF_TIMELOCK((bp), (locktype), (interlock), (wmesg), (catch),	\
-	    (timo), LOCK_FILE, LOCK_LINE)
-
-/*
  * Buffer lock assertions.
  */
 #if defined(INVARIANTS) && defined(INVARIANT_SUPPORT)
@@ -373,6 +343,12 @@
 	_lockmgr_disown(&(bp)->b_lock, LOCK_FILE, LOCK_LINE)
 #endif
 
+/*
+ * Find out if the lock has waiters or not.
+ */
+#define	BUF_LOCKWAITERS(bp)						\
+	lockmgr_waiters(&(bp)->b_lock)
+
 #endif /* _KERNEL */
 
 struct buf_queue_head {
@@ -528,7 +504,7 @@
 int	vmapbuf(struct buf *);
 void	vunmapbuf(struct buf *);
 void	relpbuf(struct buf *, int *);
-int	brelvp(struct buf *);
+void	brelvp(struct buf *);
 void	bgetvp(struct vnode *, struct buf *);
 void	pbgetbo(struct bufobj *bo, struct buf *bp);
 void	pbgetvp(struct vnode *, struct buf *);
--- //depot/vendor/freebsd/src/sys/sys/lockmgr.h	2008/03/01 22:16:36
+++ //depot/user/attilio/attilio_schedlock/sys/lockmgr.h	2008/03/28 01:22:10
@@ -225,6 +225,8 @@
 	    LOCK_FILE, LOCK_LINE)
 #define	lockmgr_recursed(lkp)						\
 	((lkp)->lk_exclusivecount > 1)
+#define	lockmgr_waiters(lkp)						\
+	((lkp)->lk_waitcount != 0)
 #ifdef INVARIANTS
 #define	lockmgr_assert(lkp, what)					\
 	_lockmgr_assert((lkp), (what), LOCK_FILE, LOCK_LINE)