device-mapper-persistent-data/device-mapper-persistent-data-0.2.1-thin_dump-support-metadata-snap-block.patch

diff --git a/thin-provisioning/metadata.cc b/thin-provisioning/metadata.cc
index c841614..771325a 100644
--- a/thin-provisioning/metadata.cc
+++ b/thin-provisioning/metadata.cc
@@ -57,15 +57,6 @@ namespace {
 		return tm;
 	}
 
-	superblock
-	read_superblock(block_manager<>::ptr bm, block_address location = SUPERBLOCK_LOCATION) {
-		superblock sb;
-		block_manager<>::read_ref r = bm->read_lock(location, superblock_validator());
-		superblock_disk const *sbd = reinterpret_cast<superblock_disk const *>(&r.data());
-		superblock_traits::unpack(*sbd, sb);
-		return sb;
-	}
-
 	void
 	copy_space_maps(space_map::ptr lhs, space_map::ptr rhs) {
 		for (block_address b = 0; b < rhs->get_nr_blocks(); b++) {
@@ -149,10 +140,10 @@ metadata::metadata(std::string const &dev_path, open_type ot,
 	}
 }
 
-metadata::metadata(std::string const &dev_path)
+metadata::metadata(std::string const &dev_path, block_address metadata_snap)
 {
 	tm_ = open_tm(open_bm(dev_path, false));
-	sb_ = read_superblock(tm_->get_bm());
+	sb_ = read_superblock(tm_->get_bm(), metadata_snap);
 
 	// We don't open the metadata sm for a held root
 	//metadata_sm_ = open_metadata_sm(tm_, &sb_.metadata_space_map_root_);
diff --git a/thin-provisioning/metadata.h b/thin-provisioning/metadata.h
index 250c216..9749acb 100644
--- a/thin-provisioning/metadata.h
+++ b/thin-provisioning/metadata.h
@@ -62,10 +62,11 @@ namespace thin_provisioning {
 		// Deprecated: it would be better if we passed in an already
 		// constructed block_manager.
 		metadata(std::string const &dev_path, open_type ot,
-			 sector_t data_block_size = 128,
+			 sector_t data_block_size = 128, // Only used if CREATE
 			 block_address nr_data_blocks = 0); // Only used if CREATE
 
-		metadata(std::string const &dev_path);
+		metadata(std::string const &dev_path,
+			 block_address metadata_snap = 0);
 
 		// ... use these instead ...
 		metadata(block_manager<>::ptr bm, open_type ot,
diff --git a/thin-provisioning/superblock.cc b/thin-provisioning/superblock.cc
index c23fbc1..bf9544b 100644
--- a/thin-provisioning/superblock.cc
+++ b/thin-provisioning/superblock.cc
@@ -126,17 +126,22 @@ namespace thin_provisioning {
 		}
 	}
 
-	superblock_detail::superblock read_superblock(block_manager<>::ptr bm)
+	superblock_detail::superblock read_superblock(block_manager<>::ptr bm, block_address location)
 	{
 		using namespace superblock_detail;
 
 		superblock sb;
-		auto r = bm->read_lock(SUPERBLOCK_LOCATION, superblock_validator());
+		auto r = bm->read_lock(location, superblock_validator());
 		superblock_disk const *sbd = reinterpret_cast<superblock_disk const *>(&r.data());
 		superblock_traits::unpack(*sbd, sb);
 		return sb;
 	}
 
+	superblock_detail::superblock read_superblock(block_manager<>::ptr bm)
+	{
+		return read_superblock(bm, SUPERBLOCK_LOCATION);
+	}
+
 	void
 	check_superblock(block_manager<>::ptr bm,
 			 superblock_detail::damage_visitor &visitor) {
diff --git a/thin-provisioning/superblock.h b/thin-provisioning/superblock.h
index e993497..a9377b0 100644
--- a/thin-provisioning/superblock.h
+++ b/thin-provisioning/superblock.h
@@ -123,6 +123,7 @@ namespace thin_provisioning {
 	persistent_data::block_manager<>::validator::ptr superblock_validator();
 
 	superblock_detail::superblock read_superblock(persistent_data::block_manager<>::ptr bm);
+	superblock_detail::superblock read_superblock(persistent_data::block_manager<>::ptr bm, persistent_data::block_address location);
 	void check_superblock(persistent_data::block_manager<>::ptr bm,
 			      superblock_detail::damage_visitor &visitor);
 }
diff --git a/thin-provisioning/thin_dump.cc b/thin-provisioning/thin_dump.cc
index a4bcf66..029a635 100644
--- a/thin-provisioning/thin_dump.cc
+++ b/thin-provisioning/thin_dump.cc
@@ -35,7 +35,7 @@ namespace {
 	int dump(string const &path, ostream &out, string const &format, bool repair,
 		 block_address metadata_snap = 0) {
 		try {
-			metadata::ptr md(new metadata(path, metadata::OPEN));
+			metadata::ptr md(metadata_snap ? new metadata(path, metadata_snap) : new metadata(path, metadata::OPEN, 0, 0));
 			emitter::ptr e;
 
 			if (format == "xml")
@@ -63,7 +63,7 @@ namespace {
 		    << "  {-h|--help}" << endl
 		    << "  {-f|--format} {xml|human_readable}" << endl
 		    << "  {-r|--repair}" << endl
-		    << "  {-m|--metadata-snap}" << endl
+		    << "  {-m|--metadata-snap} block#" << endl
 		    << "  {-o <xml file>}" << endl
 		    << "  {-V|--version}" << endl;
 	}