diff --git a/[refs] b/[refs]
index 82e11bcc2eb8..1c318f46e285 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 1472da5fdc65f0cd286c655758d629346001e126
+refs/heads/master: c56818d7dc976a7392be82e8e04fe26347d591f3
diff --git a/trunk/fs/quota/dquot.c b/trunk/fs/quota/dquot.c
index eb5a755718f6..cd6bb9a33c13 100644
--- a/trunk/fs/quota/dquot.c
+++ b/trunk/fs/quota/dquot.c
@@ -2164,7 +2164,9 @@ int vfs_quota_on_mount(struct super_block *sb, char *qf_name,
 	struct dentry *dentry;
 	int error;
 
+	mutex_lock(&sb->s_root->d_inode->i_mutex);
 	dentry = lookup_one_len(qf_name, sb->s_root, strlen(qf_name));
+	mutex_unlock(&sb->s_root->d_inode->i_mutex);
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);