From f581f34be868201a1ea955178fd4e6ad932c9219 Mon Sep 17 00:00:00 2001
From: Joe Thornber <ejt@redhat.com>
Date: Tue, 7 Apr 2015 12:10:38 +0100
Subject: [PATCH] add comment explaining mtree_traits

---
 thin-provisioning/mapping_tree.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/thin-provisioning/mapping_tree.h b/thin-provisioning/mapping_tree.h
index be3bcf8..d417b47 100644
--- a/thin-provisioning/mapping_tree.h
+++ b/thin-provisioning/mapping_tree.h
@@ -54,6 +54,9 @@ namespace thin_provisioning {
 			transaction_manager::ptr tm_;
 		};
 
+		// This value type is itself a tree containing mappings.
+		// Used when manipulating the top level of the mapping
+		// tree.
 		struct mtree_traits {
 			typedef base::le64 disk_type;
 			typedef uint64_t value_type;