diff --git a/Makefile.in b/Makefile.in
index 1d37887..2822626 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -54,10 +54,9 @@ SOURCE=\
 	thin-provisioning/mapping_tree.cc \
 	thin-provisioning/metadata.cc \
 	thin-provisioning/metadata_checker.cc \
-	thin-provisioning/metadata_disk_structures.cc \
 	thin-provisioning/metadata_dumper.cc \
 	thin-provisioning/restore_emitter.cc \
-	thin-provisioning/superblock_checker.cc \
+	thin-provisioning/superblock.cc \
 	thin-provisioning/superblock_validator.cc \
 	thin-provisioning/thin_pool.cc \
 	thin-provisioning/xml_format.cc
@@ -139,8 +138,7 @@ THIN_CHECK_SOURCE=\
 	thin-provisioning/file_utils.cc \
 	thin-provisioning/metadata.cc \
 	thin-provisioning/metadata_checker.cc \
-	thin-provisioning/metadata_disk_structures.cc \
-	thin-provisioning/superblock_checker.cc \
+	thin-provisioning/superblock.cc \
 	thin-provisioning/superblock_validator.cc
 
 THIN_DEBUG_OBJECTS=$(subst .cc,.o,$(THIN_DEBUG_SOURCE))
diff --git a/persistent-data/data-structures/ref_counter.h b/persistent-data/data-structures/ref_counter.h
index f4ef791..88937e8 100644
--- a/persistent-data/data-structures/ref_counter.h
+++ b/persistent-data/data-structures/ref_counter.h
@@ -19,6 +19,8 @@
 #ifndef REF_COUNTER_H
 #define REF_COUNTER_H
 
+#include <boost/shared_ptr.hpp>
+
 //----------------------------------------------------------------
 
 namespace persistent_data {
diff --git a/thin-provisioning/metadata.cc b/thin-provisioning/metadata.cc
index 326bd3c..0639cc1 100644
--- a/thin-provisioning/metadata.cc
+++ b/thin-provisioning/metadata.cc
@@ -37,6 +37,8 @@ using namespace thin_provisioning;
 //----------------------------------------------------------------
 
 namespace {
+	using namespace superblock_detail;
+
 	unsigned const METADATA_CACHE_SIZE = 1024;
 
 	block_manager<>::ptr open_bm(string const &dev_path, bool writeable) {
diff --git a/thin-provisioning/metadata.h b/thin-provisioning/metadata.h
index 27df10c..3861827 100644
--- a/thin-provisioning/metadata.h
+++ b/thin-provisioning/metadata.h
@@ -25,9 +25,9 @@
 #include "persistent-data/space-maps/disk.h"
 #include "persistent-data/transaction_manager.h"
 
-#include "thin-provisioning/metadata_disk_structures.h"
 #include "thin-provisioning/device_tree.h"
 #include "thin-provisioning/mapping_tree.h"
+#include "thin-provisioning/superblock.h"
 
 //----------------------------------------------------------------
 
@@ -77,7 +77,7 @@ namespace thin_provisioning {
 
 
 		tm_ptr tm_;
-		superblock sb_;
+		superblock_detail::superblock sb_;
 
 		checked_space_map::ptr metadata_sm_;
 		checked_space_map::ptr data_sm_;
diff --git a/thin-provisioning/metadata_checker.cc b/thin-provisioning/metadata_checker.cc
index 1d064a7..548ea2f 100644
--- a/thin-provisioning/metadata_checker.cc
+++ b/thin-provisioning/metadata_checker.cc
@@ -25,7 +25,7 @@ using namespace persistent_data;
 using namespace thin_provisioning;
 
 //----------------------------------------------------------------
-
+#if 0
 void
 metadata_damage::set_message(std::string const &message)
 {
@@ -436,3 +436,4 @@ thin_provisioning::metadata_check(std::string const &dev_path)
 
 //----------------------------------------------------------------
 #endif
+#endif
diff --git a/thin-provisioning/metadata_checker.h b/thin-provisioning/metadata_checker.h
index 877f1b5..890b937 100644
--- a/thin-provisioning/metadata_checker.h
+++ b/thin-provisioning/metadata_checker.h
@@ -29,7 +29,18 @@
 //----------------------------------------------------------------
 
 namespace thin_provisioning {
-	class metadata_damage_visitor;
+	// FIXME: should take a block manager or transaction manager
+	void check_metadata(std::string const &path);
+
+
+
+
+
+
+
+
+
+#if 0
 
 	// Base class for all types of metadata damage.  Used in reporting.
 	class metadata_damage {
@@ -143,22 +154,7 @@ namespace thin_provisioning {
 
 	typedef std::deque<metadata_damage::ptr> damage_list;
 	typedef boost::shared_ptr<damage_list> damage_list_ptr;
-
-	//--------------------------------
-
-	class checker {
-	public:
-		typedef persistent_data::block_manager<> block_manager;
-		typedef boost::shared_ptr<checker> ptr;
-
-		checker(block_manager::ptr bm);
-
-		virtual ~checker() {};
-		virtual damage_list_ptr check() = 0;
-
-	protected:
-		block_manager::ptr bm_;
-	};
+#endif
 }
 
 //----------------------------------------------------------------
diff --git a/thin-provisioning/metadata_disk_structures.h b/thin-provisioning/metadata_disk_structures.h
deleted file mode 100644
index 0b1d978..0000000
--- a/thin-provisioning/metadata_disk_structures.h
+++ /dev/null
@@ -1,114 +0,0 @@
-// Copyright (C) 2011 Red Hat, Inc. All rights reserved.
-//
-// This file is part of the thin-provisioning-tools source.
-//
-// thin-provisioning-tools is free software: you can redistribute it
-// and/or modify it under the terms of the GNU General Public License
-// as published by the Free Software Foundation, either version 3 of
-// the License, or (at your option) any later version.
-//
-// thin-provisioning-tools is distributed in the hope that it will be
-// useful, but WITHOUT ANY WARRANTY; without even the implied warranty
-// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License along
-// with thin-provisioning-tools.  If not, see
-// <http://www.gnu.org/licenses/>.
-
-#ifndef METADATA_DISK_STRUCTURES_H
-#define METADATA_DISK_STRUCTURES_H
-
-#include "persistent-data/endian_utils.h"
-#include "persistent-data/data-structures/btree.h"
-
-//----------------------------------------------------------------
-
-namespace thin_provisioning {
-	using namespace base;	// FIXME: don't use namespaces in headers.
-
-	unsigned const SPACE_MAP_ROOT_SIZE = 128;
-
-	typedef unsigned char __u8;
-
-	struct superblock_disk {
-		le32 csum_;
-		le32 flags_;
-		le64 blocknr_;
-
-		__u8 uuid_[16];
-		le64 magic_;
-		le32 version_;
-		le32 time_;
-
-		le64 trans_id_;
-		/* root for userspace's transaction (for migration and friends) */
-		le64 metadata_snap_;
-
-		__u8 data_space_map_root_[SPACE_MAP_ROOT_SIZE];
-		__u8 metadata_space_map_root_[SPACE_MAP_ROOT_SIZE];
-
-		/* 2 level btree mapping (dev_id, (dev block, time)) -> data block */
-		le64 data_mapping_root_;
-
-		/* device detail root mapping dev_id -> device_details */
-		le64 device_details_root_;
-
-		le32 data_block_size_; /* in 512-byte sectors */
-
-		le32 metadata_block_size_; /* in 512-byte sectors */
-		le64 metadata_nr_blocks_;
-
-		le32 compat_flags_;
-		le32 compat_ro_flags_;
-		le32 incompat_flags_;
-	} __attribute__ ((packed));
-
-	struct superblock {
-		uint32_t csum_;
-		uint32_t flags_;
-		uint64_t blocknr_;
-
-		unsigned char uuid_[16];
-		uint64_t magic_;
-		uint32_t version_;
-		uint32_t time_;
-
-		uint64_t trans_id_;
-		/* root for userspace's transaction (for migration and friends) */
-		uint64_t metadata_snap_;
-
-		unsigned char data_space_map_root_[SPACE_MAP_ROOT_SIZE];
-		unsigned char metadata_space_map_root_[SPACE_MAP_ROOT_SIZE];
-
-		/* 2 level btree mapping (dev_id, (dev block, time)) -> data block */
-		uint64_t data_mapping_root_;
-
-		/* device detail root mapping dev_id -> device_details */
-		uint64_t device_details_root_;
-
-		uint32_t data_block_size_; /* in 512-byte sectors */
-
-		uint32_t metadata_block_size_; /* in 512-byte sectors */
-		uint64_t metadata_nr_blocks_;
-
-		uint32_t compat_flags_;
-		uint32_t compat_ro_flags_;
-		uint32_t incompat_flags_;
-	};
-
-	struct superblock_traits {
-		typedef superblock_disk disk_type;
-		typedef superblock value_type;
-		typedef no_op_ref_counter<superblock> ref_counter;
-
-		static void unpack(superblock_disk const &disk, superblock &core);
-		static void pack(superblock const &core, superblock_disk &disk);
-	};
-
-	block_address const SUPERBLOCK_LOCATION = 0;
-}
-
-//----------------------------------------------------------------
-
-#endif
diff --git a/thin-provisioning/restore_emitter.cc b/thin-provisioning/restore_emitter.cc
index 58b5c18..ecd2fe5 100644
--- a/thin-provisioning/restore_emitter.cc
+++ b/thin-provisioning/restore_emitter.cc
@@ -16,7 +16,8 @@
 // with thin-provisioning-tools.  If not, see
 // <http://www.gnu.org/licenses/>.
 
-#include "restore_emitter.h"
+#include "thin-provisioning/restore_emitter.h"
+#include "thin-provisioning/superblock.h"
 
 using namespace boost;
 using namespace std;
@@ -25,6 +26,8 @@ using namespace thin_provisioning;
 //----------------------------------------------------------------
 
 namespace {
+	using namespace superblock_detail;
+
 	class restorer : public emitter {
 	public:
 		restorer(metadata::ptr md)
diff --git a/thin-provisioning/metadata_disk_structures.cc b/thin-provisioning/superblock.cc
similarity index 72%
rename from thin-provisioning/metadata_disk_structures.cc
rename to thin-provisioning/superblock.cc
index f484763..c9c9751 100644
--- a/thin-provisioning/metadata_disk_structures.cc
+++ b/thin-provisioning/superblock.cc
@@ -1,26 +1,8 @@
-// Copyright (C) 2011 Red Hat, Inc. All rights reserved.
-//
-// This file is part of the thin-provisioning-tools source.
-//
-// thin-provisioning-tools is free software: you can redistribute it
-// and/or modify it under the terms of the GNU General Public License
-// as published by the Free Software Foundation, either version 3 of
-// the License, or (at your option) any later version.
-//
-// thin-provisioning-tools is distributed in the hope that it will be
-// useful, but WITHOUT ANY WARRANTY; without even the implied warranty
-// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License along
-// with thin-provisioning-tools.  If not, see
-// <http://www.gnu.org/licenses/>.
-
-#include "thin-provisioning/metadata_disk_structures.h"
-
-#include <string.h>
+#include "thin-provisioning/superblock.h"
+#include "thin-provisioning/superblock_validator.h"
 
 using namespace thin_provisioning;
+using namespace superblock_detail;
 
 //----------------------------------------------------------------
 
@@ -91,3 +73,40 @@ superblock_traits::pack(superblock const &value, superblock_disk &disk)
 }
 
 //----------------------------------------------------------------
+
+
+#if 0
+superblock_checker::superblock_checker(block_manager::ptr bm)
+	: checker(bm)
+{
+}
+
+// FIXME: Other things to check:
+// - magic
+// - version
+// - 3 * flags (should be zero)
+// - in bounds: metadata_snap, data_mapping_root
+// - metadata_nr_blocks_ matches what we've been given.
+damage_list_ptr
+superblock_checker::check()
+{
+	superblock sb;
+
+	damage_list_ptr damage(new damage_list);
+
+	try {
+		block_manager::read_ref r = bm_->read_lock(SUPERBLOCK_LOCATION, superblock_validator());
+		superblock_disk const *sbd = reinterpret_cast<superblock_disk const *>(&r.data());
+		superblock_traits::unpack(*sbd, sb);
+
+	} catch (checksum_error const &e) {
+		metadata_damage::ptr err(new super_block_corruption);
+		err->set_message("checksum error");
+		damage->push_back(err);
+	}
+
+	return damage;
+}
+
+//----------------------------------------------------------------
+#endif
diff --git a/thin-provisioning/superblock.h b/thin-provisioning/superblock.h
new file mode 100644
index 0000000..ce69ef6
--- /dev/null
+++ b/thin-provisioning/superblock.h
@@ -0,0 +1,108 @@
+#ifndef THIN_SUPERBLOCK_H
+#define THIN_SUPERBLOCK_H
+
+#include "persistent-data/block.h"
+#include "persistent-data/endian_utils.h"
+#include "persistent-data/data-structures/ref_counter.h"
+
+//----------------------------------------------------------------
+
+namespace thin_provisioning {
+	namespace superblock_detail {
+		using namespace base;
+		using namespace persistent_data;
+
+		unsigned const SPACE_MAP_ROOT_SIZE = 128;
+
+		typedef unsigned char __u8;
+
+		struct superblock_disk {
+			le32 csum_;
+			le32 flags_;
+			le64 blocknr_;
+
+			__u8 uuid_[16];
+			le64 magic_;
+			le32 version_;
+			le32 time_;
+
+			le64 trans_id_;
+			/* root for userspace's transaction (for migration and friends) */
+			le64 metadata_snap_;
+
+			__u8 data_space_map_root_[SPACE_MAP_ROOT_SIZE];
+			__u8 metadata_space_map_root_[SPACE_MAP_ROOT_SIZE];
+
+			/* 2 level btree mapping (dev_id, (dev block, time)) -> data block */
+			le64 data_mapping_root_;
+
+			/* device detail root mapping dev_id -> device_details */
+			le64 device_details_root_;
+
+			le32 data_block_size_; /* in 512-byte sectors */
+
+			le32 metadata_block_size_; /* in 512-byte sectors */
+			le64 metadata_nr_blocks_;
+
+			le32 compat_flags_;
+			le32 compat_ro_flags_;
+			le32 incompat_flags_;
+		} __attribute__ ((packed));
+
+		struct superblock {
+			uint32_t csum_;
+			uint32_t flags_;
+			uint64_t blocknr_;
+
+			unsigned char uuid_[16];
+			uint64_t magic_;
+			uint32_t version_;
+			uint32_t time_;
+
+			uint64_t trans_id_;
+			/* root for userspace's transaction (for migration and friends) */
+			uint64_t metadata_snap_;
+
+			unsigned char data_space_map_root_[SPACE_MAP_ROOT_SIZE];
+			unsigned char metadata_space_map_root_[SPACE_MAP_ROOT_SIZE];
+
+			/* 2 level btree mapping (dev_id, (dev block, time)) -> data block */
+			uint64_t data_mapping_root_;
+
+			/* device detail root mapping dev_id -> device_details */
+			uint64_t device_details_root_;
+
+			uint32_t data_block_size_; /* in 512-byte sectors */
+
+			uint32_t metadata_block_size_; /* in 512-byte sectors */
+			uint64_t metadata_nr_blocks_;
+
+			uint32_t compat_flags_;
+			uint32_t compat_ro_flags_;
+			uint32_t incompat_flags_;
+		};
+
+		struct superblock_traits {
+			typedef superblock_disk disk_type;
+			typedef superblock value_type;
+			typedef no_op_ref_counter<superblock> ref_counter;
+
+			static void unpack(superblock_disk const &disk, superblock &core);
+			static void pack(superblock const &core, superblock_disk &disk);
+		};
+
+		block_address const SUPERBLOCK_LOCATION = 0;
+	}
+
+#if 0
+	class superblock_checker : public checker {
+	public:
+		superblock_checker(block_manager::ptr bm);
+		damage_list_ptr check();
+	};
+#endif
+}
+
+//----------------------------------------------------------------
+
+#endif
diff --git a/thin-provisioning/superblock_checker.cc b/thin-provisioning/superblock_checker.cc
deleted file mode 100644
index f2dd625..0000000
--- a/thin-provisioning/superblock_checker.cc
+++ /dev/null
@@ -1,43 +0,0 @@
-#include "thin-provisioning/superblock_checker.h"
-
-#include "thin-provisioning/metadata_disk_structures.h"
-#include "thin-provisioning/superblock_validator.h"
-
-
-using namespace thin_provisioning;
-
-//----------------------------------------------------------------
-
-superblock_checker::superblock_checker(block_manager::ptr bm)
-	: checker(bm)
-{
-}
-
-// FIXME: Other things to check:
-// - magic
-// - version
-// - 3 * flags (should be zero)
-// - in bounds: metadata_snap, data_mapping_root
-// - metadata_nr_blocks_ matches what we've been given.
-damage_list_ptr
-superblock_checker::check()
-{
-	superblock sb;
-
-	damage_list_ptr damage(new damage_list);
-
-	try {
-		block_manager::read_ref r = bm_->read_lock(SUPERBLOCK_LOCATION, superblock_validator());
-		superblock_disk const *sbd = reinterpret_cast<superblock_disk const *>(&r.data());
-		superblock_traits::unpack(*sbd, sb);
-
-	} catch (checksum_error const &e) {
-		metadata_damage::ptr err(new super_block_corruption);
-		err->set_message("checksum error");
-		damage->push_back(err);
-	}
-
-	return damage;
-}
-
-//----------------------------------------------------------------
diff --git a/thin-provisioning/superblock_checker.h b/thin-provisioning/superblock_checker.h
deleted file mode 100644
index fd50a5d..0000000
--- a/thin-provisioning/superblock_checker.h
+++ /dev/null
@@ -1,18 +0,0 @@
-#ifndef THIN_SUPERBLOCK_CHECKER_H
-#define THIN_SUPERBLOCK_CHECKER_H
-
-#include "thin-provisioning/metadata_checker.h"
-
-//----------------------------------------------------------------
-
-namespace thin_provisioning {
-	class superblock_checker : public checker {
-	public:
-		superblock_checker(block_manager::ptr bm);
-		damage_list_ptr check();
-	};
-}
-
-//----------------------------------------------------------------
-
-#endif
diff --git a/thin-provisioning/superblock_validator.cc b/thin-provisioning/superblock_validator.cc
index 2d59d65..1f5b561 100644
--- a/thin-provisioning/superblock_validator.cc
+++ b/thin-provisioning/superblock_validator.cc
@@ -1,12 +1,17 @@
-#include "thin-provisioning/superblock_validator.h"
+#include "persistent-data/checksum.h"
+#include "persistent-data/errors.h"
 
-#include "thin-provisioning/metadata_disk_structures.h"
+#include "thin-provisioning/superblock_validator.h"
+#include "thin-provisioning/superblock.h"
 
 using namespace thin_provisioning;
 
 //----------------------------------------------------------------
 
 namespace {
+	using namespace persistent_data;
+	using namespace superblock_detail;
+
         uint32_t const VERSION = 1;
         unsigned const SECTOR_TO_BLOCK_SHIFT = 3;
 	uint32_t const SUPERBLOCK_CSUM_SEED = 160774;
diff --git a/thin-provisioning/thin_check.cc b/thin-provisioning/thin_check.cc
index b183ead..c768c0d 100644
--- a/thin-provisioning/thin_check.cc
+++ b/thin-provisioning/thin_check.cc
@@ -29,6 +29,12 @@ using namespace std;
 using namespace thin_provisioning;
 
 namespace {
+	enum error_state {
+		NO_ERRORS,
+		NON_FATAL,	// eg, lost blocks
+		FATAL		// needs fixing before pool can be activated
+	};
+
 	int check(string const &path, bool quiet) {
 		try {
 			optional<error_set::ptr> maybe_errors = metadata_check(path);