1 files changed, 11 insertions, 1 deletions
diff --git a/sys/kern/vfs_cache.c b/sys/kern/vfs_cache.c
index 88ecc35..4dfbe93 100644
--- a/sys/kern/vfs_cache.c
+++ b/sys/kern/vfs_cache.c
@@ -493,8 +493,18 @@ cache_enter(dvp, vp, cnp)
 		if (cnp->cn_namelen == 1) {
 			return;
 		}
+		/*
+		 * For dotdot lookups only cache the v_dd pointer if the
+		 * directory has a link back to its parent via v_cache_dst.
+		 * Without this an unlinked directory would keep a soft
+		 * reference to its parent which could not be NULLd at
+		 * cache_purge() time.
+		 */
 		if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
-			dvp->v_dd = vp;
+			CACHE_LOCK();
+			if (!TAILQ_EMPTY(&dvp->v_cache_dst))
+				dvp->v_dd = vp;
+			CACHE_UNLOCK();
 			return;
 		}
 	}