diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 13b7415ce892..1a683315a8e7 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -3046,6 +3046,19 @@ vrefact(struct vnode *vp)
 #endif
 }
 
+void
+vrefactn(struct vnode *vp, u_int n)
+{
+
+	CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
+#ifdef INVARIANTS
+	int old = atomic_fetchadd_int(&vp->v_usecount, n);
+	VNASSERT(old > 0, vp, ("%s: wrong use count %d", __func__, old));
+#else
+	atomic_add_int(&vp->v_usecount, n);
+#endif
+}
+
 /*
  * Return reference count of a vnode.
  *
diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h
index 08c596c1e5a8..db95d351ae19 100644
--- a/sys/sys/vnode.h
+++ b/sys/sys/vnode.h
@@ -900,6 +900,7 @@ void	vrele(struct vnode *vp);
 void	vref(struct vnode *vp);
 void	vrefl(struct vnode *vp);
 void	vrefact(struct vnode *vp);
+void	vrefactn(struct vnode *vp, u_int n);
 int	vrefcnt(struct vnode *vp);
 void 	v_addpollinfo(struct vnode *vp);