From 60b0b1aa18ca08bc1518625fdc548009fa5bf21b Mon Sep 17 00:00:00 2001
From: Tor Egge <tegge@FreeBSD.org>
Date: Wed, 20 Sep 2006 00:27:02 +0000
Subject: [PATCH] Don't try to obtain a reference to a nonexisting (NULL) mount
 structure in default VOP_GETWRITEMOUNT().

---
 sys/kern/vfs_default.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/sys/kern/vfs_default.c b/sys/kern/vfs_default.c
index bf33115407c..0232ff3e165 100644
--- a/sys/kern/vfs_default.c
+++ b/sys/kern/vfs_default.c
@@ -353,10 +353,12 @@ vop_stdgetwritemount(ap)
 	 * harmful to return with a ref to our previous mountpoint.
 	 */
 	mp = ap->a_vp->v_mount;
-	vfs_ref(mp);
-	if (mp != ap->a_vp->v_mount) {
-		vfs_rel(mp);
-		mp = NULL;
+	if (mp != NULL) {
+		vfs_ref(mp);
+		if (mp != ap->a_vp->v_mount) {
+			vfs_rel(mp);
+			mp = NULL;
+		}
 	}
 	*(ap->a_mpp) = mp;
 	return (0);