From 6fcda37dbce87c3b654f3939c7b5a949d487c466 Mon Sep 17 00:00:00 2001
From: Joe Thornber <ejt@redhat.com>
Date: Tue, 21 May 2013 14:01:17 +0100
Subject: [PATCH] superblock damage visitor

---
 thin-provisioning/metadata.cc         |  1 -
 thin-provisioning/metadata_checker.cc |  1 -
 thin-provisioning/superblock.cc       | 34 ++++++++++++++++++++++++++-
 thin-provisioning/superblock.h        | 28 ++++++++++++++++++++++
 4 files changed, 61 insertions(+), 3 deletions(-)

diff --git a/thin-provisioning/metadata.cc b/thin-provisioning/metadata.cc
index 0639cc1..08b0773 100644
--- a/thin-provisioning/metadata.cc
+++ b/thin-provisioning/metadata.cc
@@ -19,7 +19,6 @@
 #include "thin-provisioning/device_tree.h"
 #include "thin-provisioning/file_utils.h"
 #include "thin-provisioning/metadata.h"
-#include "thin-provisioning/superblock_validator.h"
 
 #include "persistent-data/math_utils.h"
 #include "persistent-data/space-maps/core.h"
diff --git a/thin-provisioning/metadata_checker.cc b/thin-provisioning/metadata_checker.cc
index 548ea2f..ae8a6c9 100644
--- a/thin-provisioning/metadata_checker.cc
+++ b/thin-provisioning/metadata_checker.cc
@@ -19,7 +19,6 @@
 #include "thin-provisioning/file_utils.h"
 #include "thin-provisioning/metadata.h"
 #include "thin-provisioning/metadata_checker.h"
-#include "thin-provisioning/superblock_validator.h"
 
 using namespace persistent_data;
 using namespace thin_provisioning;
diff --git a/thin-provisioning/superblock.cc b/thin-provisioning/superblock.cc
index 5c00d8a..96cecac 100644
--- a/thin-provisioning/superblock.cc
+++ b/thin-provisioning/superblock.cc
@@ -1,7 +1,6 @@
 #include "persistent-data/checksum.h"
 #include "persistent-data/errors.h"
 #include "thin-provisioning/superblock.h"
-#include "thin-provisioning/superblock_validator.h"
 
 using namespace thin_provisioning;
 using namespace superblock_detail;
@@ -109,3 +108,36 @@ thin_provisioning::superblock_validator()
 }
 
 //----------------------------------------------------------------
+
+namespace thin_provisioning {
+	namespace superblock_detail {
+		superblock_corruption::superblock_corruption(std::string const &desc)
+			: desc_(desc) {
+		}
+
+		void
+		superblock_corruption::visit(damage_visitor &v) const {
+			v.visit(*this);
+		}
+
+		void
+		damage_visitor::visit(damage const &d) {
+			d.visit(*this);
+		}
+	}
+
+	void
+	check_superblock(block_manager<>::ptr bm,
+			 superblock_detail::damage_visitor &visitor) {
+		using namespace superblock_detail;
+
+		try {
+			bm->read_lock(SUPERBLOCK_LOCATION, superblock_validator());
+
+		} catch (std::exception const &e) {
+			visitor.visit(superblock_corruption(e.what()));
+		}
+	}
+}
+
+//----------------------------------------------------------------
diff --git a/thin-provisioning/superblock.h b/thin-provisioning/superblock.h
index c71967d..19d8d79 100644
--- a/thin-provisioning/superblock.h
+++ b/thin-provisioning/superblock.h
@@ -93,9 +93,37 @@ namespace thin_provisioning {
 
 		block_address const SUPERBLOCK_LOCATION = 0;
 		uint32_t const SUPERBLOCK_MAGIC = 27022010;
+
+		//--------------------------------
+
+		class damage_visitor;
+
+		struct damage {
+			virtual ~damage() {}
+			virtual void visit(damage_visitor &v) const = 0;
+		};
+
+		struct superblock_corruption : public damage {
+			superblock_corruption(std::string const &desc);
+			void visit(damage_visitor &v) const;
+
+			std::string desc_;
+		};
+
+		class damage_visitor {
+		public:
+			virtual ~damage_visitor() {}
+
+			void visit(damage const &d);
+
+			virtual void visit(superblock_corruption const &d) = 0;
+		};
 	}
 
 	block_manager<>::validator::ptr superblock_validator();
+
+	void check_superblock(block_manager<>::ptr bm,
+			      superblock_detail::damage_visitor &visitor);
 }
 
 //----------------------------------------------------------------