[block_manager] Hard code block size to 4k.

We're never going to use anything other than 4k, and by hard coding it we
avoid making block_manager a template.

persistent-data/block.cc

@@ -0,0 +1,203 @@
+// 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 "block.h"
+
+#include "base/error_string.h"
+#include "base/file_utils.h"
+#include "block-cache/io_engine.h"
+
+#include <boost/bind.hpp>
+#include <stdexcept>
+
+using namespace persistent_data;
+
+//----------------------------------------------------------------
+
+block_manager::read_ref::read_ref(block_cache::block &b)
+	: b_(b)
+{
+}
+
+block_manager::read_ref::read_ref(read_ref const &rhs)
+	: b_(rhs.b_)
+{
+	b_.get();
+}
+
+block_manager::read_ref::~read_ref()
+{
+	b_.put();
+}
+
+block_address
+block_manager::read_ref::get_location() const
+{
+	return b_.get_index();
+}
+
+void const *
+block_manager::read_ref::data() const
+{
+	return b_.get_data();
+}
+
+//--------------------------------
+
+block_manager::write_ref::write_ref(block_cache::block &b)
+	: read_ref(b),
+	  ref_count_(NULL)
+{
+}
+
+block_manager::write_ref::write_ref(block_cache::block &b, unsigned &ref_count)
+	: read_ref(b),
+	  ref_count_(&ref_count) {
+	if (*ref_count_)
+		throw std::runtime_error("superblock already locked");
+	(*ref_count_)++;
+}
+
+block_manager::write_ref::write_ref(write_ref const &rhs)
+	: read_ref(rhs),
+	  ref_count_(rhs.ref_count_) {
+	if (ref_count_)
+		(*ref_count_)++;
+}
+
+block_manager::write_ref::~write_ref()
+{
+	if (ref_count_) {
+		if (!*ref_count_) {
+			std::cerr << "write_ref ref_count going below zero";
+			::exit(1);
+		}
+
+		(*ref_count_)--;
+	}
+}
+
+void *
+block_manager::write_ref::data()
+{
+	return read_ref::b_.get_data();
+}
+
+//----------------------------------------------------------------
+
+uint64_t
+block_manager::choose_cache_size(block_address nr_blocks) const
+{
+	uint64_t const DEFAULT_CACHE_SIZE = 1024 * 1024 * 16;
+	return std::min<uint64_t>(DEFAULT_CACHE_SIZE, MD_BLOCK_SIZE * nr_blocks);
+}
+
+block_manager::block_manager(std::string const &path,
+					block_address nr_blocks,
+					unsigned max_concurrent_blocks,
+					mode m,
+					bool excl)
+	: fd_(open_or_create_block_file(path, nr_blocks * MD_BLOCK_SIZE, m, excl)),
+	  bc_(fd_, MD_BLOCK_SIZE >> SECTOR_SHIFT, nr_blocks, choose_cache_size(nr_blocks)),
+	  superblock_ref_count_(0)
+{
+}
+
+file_utils::file_descriptor
+block_manager::open_or_create_block_file(std::string const &path, off_t file_size, mode m, bool excl)
+{
+	switch (m) {
+	case READ_ONLY:
+		return file_utils::open_block_file(path, file_size, false, excl);
+
+	case READ_WRITE:
+		return file_utils::open_block_file(path, file_size, true, excl);
+
+	case CREATE:
+		return file_utils::create_block_file(path, file_size);
+
+	default:
+		throw std::runtime_error("unsupported mode");
+	}
+}
+
+block_manager::read_ref
+block_manager::read_lock(block_address location,
+			 typename bcache::validator::ptr v) const
+{
+	block_cache::block &b = bc_.get(location, 0, v);
+	return read_ref(b);
+}
+
+block_manager::write_ref
+block_manager::write_lock(block_address location,
+			  typename bcache::validator::ptr v)
+{
+	block_cache::block &b = bc_.get(location, block_cache::GF_DIRTY, v);
+	return write_ref(b);
+}
+
+block_manager::write_ref
+block_manager::write_lock_zero(block_address location,
+			       typename bcache::validator::ptr v)
+{
+	block_cache::block &b = bc_.get(location, block_cache::GF_ZERO, v);
+	return write_ref(b);
+}
+
+block_manager::write_ref
+block_manager::superblock(block_address location,
+			  typename bcache::validator::ptr v)
+{
+	if (bc_.get_nr_locked() > 0)
+		throw std::runtime_error("attempt to lock superblock while other locks are still held");
+
+	block_cache::block &b = bc_.get(location, block_cache::GF_DIRTY | block_cache::GF_BARRIER, v);
+	return write_ref(b, superblock_ref_count_);
+}
+
+block_manager::write_ref
+block_manager::superblock_zero(block_address location,
+			       typename bcache::validator::ptr v)
+{
+	if (bc_.get_nr_locked() > 0)
+		throw std::runtime_error("attempt to lock superblock while other locks are still held");
+
+	block_cache::block &b = bc_.get(location, block_cache::GF_ZERO | block_cache::GF_BARRIER, v);
+	return write_ref(b, superblock_ref_count_);
+}
+
+block_address
+block_manager::get_nr_blocks() const
+{
+	return bc_.get_nr_blocks();
+}
+
+void
+block_manager::prefetch(block_address b) const
+{
+	bc_.prefetch(b);
+}
+
+void
+block_manager::flush() const
+{
+	bc_.flush();
+}
+
+//----------------------------------------------------------------