Index: vfs_mount.c
===================================================================
RCS file: /usr/repo/src/sys/kern/vfs_mount.c,v
retrieving revision 1.190
diff -u -p -r1.190 vfs_mount.c
--- vfs_mount.c	19 Apr 2005 06:23:59 -0000	1.190
+++ vfs_mount.c	19 Apr 2005 12:26:49 -0000
@@ -1012,11 +1012,16 @@ struct root_hold_token {
 static LIST_HEAD(, root_hold_token)	root_holds =
     LIST_HEAD_INITIALIZER(&root_holds);
 
+static boolean_t root_mounted = 0;
+
 struct root_hold_token *
 root_mount_hold(const char *identifier)
 {
 	struct root_hold_token *h;
 
+	/* If root is already mounted, there is nothing to hold. */
+	if (root_mounted)
+		return (NULL);
 	h = malloc(sizeof *h, M_DEVBUF, M_ZERO | M_WAITOK);
 	h->who = identifier;
 	mtx_lock(&mountlist_mtx);
@@ -1029,6 +1034,9 @@ void
 root_mount_rel(struct root_hold_token *h)
 {
 
+	/* Ignore NULL tokens. */
+	if (h == NULL)
+		return;
 	mtx_lock(&mountlist_mtx);
 	LIST_REMOVE(h, list);
 	wakeup(&root_holds);
@@ -1330,6 +1338,8 @@ vfs_mountroot_try(const char *mountfrom)
 		} while (mp != NULL);
 
 		devfs_fixup(curthread);
+
+		root_mounted = 1;
 	}
 	return (error);
 }