diff --git a/sys/fs/nullfs/null_vnops.c b/sys/fs/nullfs/null_vnops.c
--- a/sys/fs/nullfs/null_vnops.c
+++ b/sys/fs/nullfs/null_vnops.c
@@ -1127,6 +1127,23 @@
 	return (res);
 }
 
+static int
+null_getlowvnode(struct vop_getlowvnode_args *ap)
+{
+	struct vnode *vp, *vpl;
+
+	vp = ap->a_vp;
+	if (vn_lock(vp, LK_SHARED) != 0)
+		return (EBADF);
+
+	vpl = NULLVPTOLOWERVP(vp);
+	vhold(vpl);
+	VOP_UNLOCK(vp);
+	VOP_GETLOWVNODE(vpl, ap->a_vplp, ap->a_flags);
+	vdrop(vpl);
+	return (0);
+}
+
 /*
  * Global vfs data structures
  */
@@ -1139,6 +1156,7 @@
 	.vop_bmap =		VOP_EOPNOTSUPP,
 	.vop_stat =		null_stat,
 	.vop_getattr =		null_getattr,
+	.vop_getlowvnode =	null_getlowvnode,
 	.vop_getwritemount =	null_getwritemount,
 	.vop_inactive =		null_inactive,
 	.vop_need_inactive =	null_need_inactive,
diff --git a/sys/kern/vfs_default.c b/sys/kern/vfs_default.c
--- a/sys/kern/vfs_default.c
+++ b/sys/kern/vfs_default.c
@@ -82,6 +82,7 @@
 static int vop_stdread_pgcache(struct vop_read_pgcache_args *ap);
 static int vop_stdstat(struct vop_stat_args *ap);
 static int vop_stdvput_pair(struct vop_vput_pair_args *ap);
+static int vop_stdgetlowvnode(struct vop_getlowvnode_args *ap);
 
 /*
  * This vnode table stores what we want to do if the filesystem doesn't
@@ -112,6 +113,7 @@
 	.vop_fsync =		VOP_NULL,
 	.vop_stat =		vop_stdstat,
 	.vop_fdatasync =	vop_stdfdatasync,
+	.vop_getlowvnode = 	vop_stdgetlowvnode,
 	.vop_getpages =		vop_stdgetpages,
 	.vop_getpages_async =	vop_stdgetpages_async,
 	.vop_getwritemount = 	vop_stdgetwritemount,
@@ -1607,3 +1609,11 @@
 		vput(vp);
 	return (0);
 }
+
+static int
+vop_stdgetlowvnode(struct vop_getlowvnode_args *ap)
+{
+	vref(ap->a_vp);
+	*ap->a_vplp = ap->a_vp;
+	return (0);
+}
diff --git a/sys/kern/vnode_if.src b/sys/kern/vnode_if.src
--- a/sys/kern/vnode_if.src
+++ b/sys/kern/vnode_if.src
@@ -468,6 +468,13 @@
 	OUT struct mount **mpp;
 };
 
+%% getwritevnode vp	= = =
+
+vop_getlowvnode {
+	IN struct vnode *vp;
+	OUT struct vnode **vplp;
+	IN int flags;
+};
 
 %% print	vp	- - -