vfs: switch i_dentry/d_alias to hlist

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 17fd887..f06db6b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -826,7 +826,7 @@
 	struct list_head	i_lru;		/* inode LRU list */
 	struct list_head	i_sb_list;
 	union {
-		struct list_head	i_dentry;
+		struct hlist_head	i_dentry;
 		struct rcu_head		i_rcu;
 	};
 	u64			i_version;