Index: zfs_vfsops.c
===================================================================
--- zfs_vfsops.c	(revision 248210)
+++ zfs_vfsops.c	(working copy)
@@ -1880,6 +1880,28 @@
 	return (0);
 }
 
+/* Undo non-transient changes made by zfs_umount() on failure. */
+static void
+zfs_umount_failure(zfsvfs_t *zfsvfs, int fflag, boolean_t dropped)
+{
+	vnode_t *vp;
+
+	if (!zfsvfs->z_issnap && zfsvfs->z_ctldir == NULL) {
+		zfsctl_create(zfsvfs);
+		ASSERT(zfsvfs->z_ctldir != NULL);
+	}
+	if (dropped) {
+		/* restore the zfs_mount() reference if needed */
+		VERIFY(VFS_ROOT(zfsvfs->z_vfs, LK_EXCLUSIVE, &vp) == 0);
+		VOP_UNLOCK(vp, 0);
+	}
+	if (fflag & MS_FORCE) {
+		rrw_enter(&zfsvfs->z_teardown_lock, RW_WRITER, FTAG);
+		zfsvfs->z_unmounted = B_FALSE;
+		rrw_exit(&zfsvfs->z_teardown_lock, FTAG);
+	}
+}
+
 /*ARGSUSED*/
 static int
 zfs_umount(vfs_t *vfsp, int fflag)
@@ -1939,10 +1961,7 @@
 	 */
 	ret = vflush(vfsp, 1, (fflag & MS_FORCE) ? FORCECLOSE : 0, td);
 	if (ret != 0) {
-		if (!zfsvfs->z_issnap) {
-			zfsctl_create(zfsvfs);
-			ASSERT(zfsvfs->z_ctldir != NULL);
-		}
+		zfs_umount_failure(zfsvfs, fflag, /*dropped*/B_FALSE);
 		return (ret);
 	}
 
@@ -1959,12 +1978,16 @@
 		 */
 		if (zfsvfs->z_ctldir == NULL) {
 			if (vfsp->vfs_count > 1)
-				return (EBUSY);
+				ret = EBUSY;
 		} else {
 			if (vfsp->vfs_count > 2 ||
 			    zfsvfs->z_ctldir->v_count > 1)
-				return (EBUSY);
+				ret = EBUSY;
 		}
+		if (ret) {
+			zfs_umount_failure(zfsvfs, fflag, /*dropped*/B_TRUE);
+			return (ret);
+		}
 	}
 
 	VERIFY(zfsvfs_teardown(zfsvfs, B_TRUE) == 0);