diff --git a/fs/dcache.c b/fs/dcache.c
index ce5a7e6..761e31b 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1184,6 +1184,39 @@
 EXPORT_SYMBOL(have_submounts);
 
 /*
+ * Called by mount code to set a mountpoint and check if the mountpoint is
+ * reachable (e.g. NFS can unhash a directory dentry and then the complete
+ * subtree can become unreachable).
+ *
+ * Only one of check_submounts_and_drop() and d_set_mounted() must succeed.  For
+ * this reason take rename_lock and d_lock on dentry and ancestors.
+ */
+int d_set_mounted(struct dentry *dentry)
+{
+	struct dentry *p;
+	int ret = -ENOENT;
+	write_seqlock(&rename_lock);
+	for (p = dentry->d_parent; !IS_ROOT(p); p = p->d_parent) {
+		/* Need exclusion wrt. check_submounts_and_drop() */
+		spin_lock(&p->d_lock);
+		if (unlikely(d_unhashed(p))) {
+			spin_unlock(&p->d_lock);
+			goto out;
+		}
+		spin_unlock(&p->d_lock);
+	}
+	spin_lock(&dentry->d_lock);
+	if (!d_unlinked(dentry)) {
+		dentry->d_flags |= DCACHE_MOUNTED;
+		ret = 0;
+	}
+ 	spin_unlock(&dentry->d_lock);
+out:
+	write_sequnlock(&rename_lock);
+	return ret;
+}
+
+/*
  * Search the dentry child list of the specified parent,
  * and move any unused dentries to the end of the unused
  * list for prune_dcache(). We descend to the next level
diff --git a/fs/internal.h b/fs/internal.h
index 7c5f01c..d208937 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -126,6 +126,7 @@
  * dcache.c
  */
 extern struct dentry *__d_alloc(struct super_block *, const struct qstr *);
+extern int d_set_mounted(struct dentry *dentry);
 
 /*
  * read_write.c
diff --git a/fs/namespace.c b/fs/namespace.c
index ad8ea9b..5997887 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -611,6 +611,7 @@
 {
 	struct list_head *chain = mountpoint_hashtable + hash(NULL, dentry);
 	struct mountpoint *mp;
+	int ret;
 
 	list_for_each_entry(mp, chain, m_hash) {
 		if (mp->m_dentry == dentry) {
@@ -626,14 +627,12 @@
 	if (!mp)
 		return ERR_PTR(-ENOMEM);
 
-	spin_lock(&dentry->d_lock);
-	if (d_unlinked(dentry)) {
-		spin_unlock(&dentry->d_lock);
+	ret = d_set_mounted(dentry);
+	if (ret) {
 		kfree(mp);
-		return ERR_PTR(-ENOENT);
+		return ERR_PTR(ret);
 	}
-	dentry->d_flags |= DCACHE_MOUNTED;
-	spin_unlock(&dentry->d_lock);
+
 	mp->m_dentry = dentry;
 	mp->m_count = 1;
 	list_add(&mp->m_hash, chain);