diff --git a/sys/kern/vfs_lookup.c b/sys/kern/vfs_lookup.c
--- a/sys/kern/vfs_lookup.c
+++ b/sys/kern/vfs_lookup.c
@@ -161,40 +161,17 @@
  * gets allocated early. See nameiinit for the direct call below.
  */
 
-/*
- * Returns busied the mount point mounted on the passed vnode, if any.
- *
- * The vnode's lock must be held and may be released on output, as indicated by
- * '*unlocked'.  The caller must also have an active reference on the vnode
- * (vref() or vget()) which is preserved across the call.  On success, the
- * busied mount point is passed through 'mp'.
- *
- * If the vnode is not mounted-on, EJUSTRETURN is returned and '*mp' is set to
- * NULL.  Concurrent unmounts/remounts of the covering mount are handled
- * transparently by restarting the process (doing so is currently not really
- * necessary for correctness but is closer to the historical behavior where the
- * unmounts/remounts were prevented to happen in this case, and will be required
- * (but not enough) if we ever want to implement such things as atomic mount
- * substitutions).  ENOENT is returned if the vnode was doomed while trying to
- * determine its covering mount, and '*mp' is set to NULL.  Else, '*mp' is set
- * to the busied mount point and 0 is returned.
- */
+/* See vn_busy_mountedhere() in 'vnode.h'. */
 int
-vn_busy_mountedhere(struct vnode *vp, bool *unlocked, struct mount **mp)
+vn_busy_mountedhere_mounted(struct vnode *vp, bool *unlocked, struct mount **mp)
 {
 	int error;
 
 	ASSERT_VOP_LOCKED(vp, __func__);
 	ASSERT_VI_UNLOCKED(vp, __func__);
-
-	*unlocked = false;
-	*mp = NULL;
-
-	if (VN_IS_DOOMED(vp))
-		return (ENOENT);
-
-	if (__predict_true((vn_irflag_read(vp) & VIRF_MOUNTPOINT) == 0))
-		return (EJUSTRETURN);
+	VNASSERT(!VN_IS_DOOMED(vp), vp, ("Input vnode is doomed"));
+	VNASSERT((vn_irflag_read(vp) & VIRF_MOUNTPOINT) != 0, vp,
+	    ("Not a mount point"));
 
 	*mp = vp->v_mountedhere;
 	MPASS(*mp != NULL);
@@ -206,8 +183,10 @@
 	 * vfs_ref()/vfs_rel() calls.
 	 */
 	error = vfs_busy(*mp, MBF_NOWAIT);
-	if (__predict_true(error == 0))
+	if (__predict_true(error == 0)) {
+		*unlocked = false;
 		return (error);
+	}
 
 	/* Make sure '*mp' survives the unlock of 'vp'. */
 	vfs_ref(*mp);
diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h
--- a/sys/sys/vnode.h
+++ b/sys/sys/vnode.h
@@ -826,8 +826,8 @@
 int	vn_io_fault_pgmove(vm_page_t ma[], vm_offset_t offset, int xfersize,
 	    struct uio *uio);
 
-int	vn_busy_mountedhere(struct vnode *vp, bool *unlocked,
-	    struct mount **mp);
+static inline int
+vn_busy_mountedhere(struct vnode *vp, bool *unlocked, struct mount **mp);
 int	vn_cross_single_mount(struct vnode* vp, int root_lkflags,
 	    bool *unlocked, struct vnode **vpp);
 int	vn_cross_mounts(struct vnode* vp, int lkflags, struct vnode **vpp);
@@ -1092,6 +1092,46 @@
 int vnode_create_vobject(struct vnode *vp, off_t size, struct thread *td);
 void vnode_destroy_vobject(struct vnode *vp);
 
+/* Internal function to implement next function. */
+int	vn_busy_mountedhere_mounted(struct vnode *vp, bool *unlocked,
+	    struct mount **mp);
+
+/*
+ * Returns busied the mount point mounted on the passed vnode, if any.
+ *
+ * The vnode's lock must be held and may be released on output, as indicated by
+ * '*unlocked'.  The caller must also have an active reference on the vnode
+ * (vref() or vget()) which is preserved across the call.  The vnode must not
+ * have been doomed.  On success, the busied mount point is passed through 'mp'.
+ *
+ * If the vnode is not mounted-on, EJUSTRETURN is returned and '*mp' is set to
+ * NULL.  Concurrent unmounts/remounts of the covering mount are handled
+ * transparently by restarting the process (doing so is currently not really
+ * necessary for correctness but is closer to the historical behavior where the
+ * unmounts/remounts were prevented to happen in this case, and will be required
+ * (but not enough) if we ever want to implement such things as atomic mount
+ * substitutions).  ENOENT is returned if the vnode was doomed while trying to
+ * determine its covering mount (which can happen because its lock may have been
+ * released in the contended case), and '*mp' is set to NULL.  Else, '*mp' is
+ * set to the busied mount point and 0 is returned.
+ */
+static inline int
+vn_busy_mountedhere(struct vnode *vp, bool *unlocked, struct mount **mp)
+{
+	ASSERT_VOP_LOCKED(vp, __func__);
+	ASSERT_VI_UNLOCKED(vp, __func__);
+	VNASSERT(!VN_IS_DOOMED(vp), vp, ("Input vnode is doomed"));
+
+	if (__predict_true((vn_irflag_read(vp) & VIRF_MOUNTPOINT) == 0)) {
+		*unlocked = false;
+		*mp = NULL;
+		return (EJUSTRETURN);
+	}
+
+	return (vn_busy_mountedhere_mounted(vp, unlocked, mp));
+}
+
+
 extern struct vop_vector fifo_specops;
 extern struct vop_vector dead_vnodeops;
 extern struct vop_vector default_vnodeops;