thin-provisioning-tools/persistent-data/block.tcc

// 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>

//----------------------------------------------------------------

namespace persistent_data {
	template <uint32_t BlockSize>
	block_manager<BlockSize>::read_ref::read_ref(block_cache::block &b)
		: b_(b)
	{
	}

	template <uint32_t BlockSize>
	block_manager<BlockSize>::read_ref::read_ref(read_ref const &rhs)
		: b_(rhs.b_)
	{
		b_.get();
	}

	template <uint32_t BlockSize>
	block_manager<BlockSize>::read_ref::~read_ref()
	{
		b_.put();
	}

	template <uint32_t BlockSize>
	block_address
	block_manager<BlockSize>::read_ref::get_location() const
	{
		return b_.get_index();
	}

	template <uint32_t BlockSize>
	void const *
	block_manager<BlockSize>::read_ref::data() const
	{
		return b_.get_data();
	}

	//--------------------------------

	template <uint32_t BlockSize>
	block_manager<BlockSize>::write_ref::write_ref(block_cache::block &b)
		: read_ref(b),
		  ref_count_(NULL)
	{
	}

	template <uint32_t BlockSize>
	block_manager<BlockSize>::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_)++;
	}

	template <uint32_t BlockSize>
	block_manager<BlockSize>::write_ref::write_ref(write_ref const &rhs)
		: read_ref(rhs),
		  ref_count_(rhs.ref_count_) {
		if (ref_count_)
			(*ref_count_)++;
	}

	template <uint32_t BlockSize>
	block_manager<BlockSize>::write_ref::~write_ref()
	{
		if (ref_count_) {
			if (!*ref_count_) {
				std::cerr << "write_ref ref_count going below zero";
				::exit(1);
			}

			(*ref_count_)--;
		}
	}

	template <uint32_t BlockSize>
	void *
	block_manager<BlockSize>::write_ref::data()
	{
		return read_ref::b_.get_data();
	}

	//----------------------------------------------------------------

	template <uint32_t BlockSize>
	uint64_t
	block_manager<BlockSize>::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, BlockSize * nr_blocks);
	}

	template <uint32_t BlockSize>
	block_manager<BlockSize>::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 * BlockSize, m, excl)),
		  bc_(fd_, BlockSize >> SECTOR_SHIFT, nr_blocks, choose_cache_size(nr_blocks)),
		  superblock_ref_count_(0)
	{
	}

	template <uint32_t BlockSize>
	file_utils::file_descriptor
	block_manager<BlockSize>::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");
		}
	}

	template <uint32_t BlockSize>
	typename block_manager<BlockSize>::read_ref
	block_manager<BlockSize>::read_lock(block_address location,
					    typename bcache::validator::ptr v) const
	{
		block_cache::block &b = bc_.get(location, 0, v);
		return read_ref(b);
	}

	template <uint32_t BlockSize>
	typename block_manager<BlockSize>::write_ref
	block_manager<BlockSize>::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);
	}

	template <uint32_t BlockSize>
	typename block_manager<BlockSize>::write_ref
	block_manager<BlockSize>::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);
	}

	template <uint32_t BlockSize>
	typename block_manager<BlockSize>::write_ref
	block_manager<BlockSize>::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_);
	}

	template <uint32_t BlockSize>
	typename block_manager<BlockSize>::write_ref
	block_manager<BlockSize>::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_);
	}

	template <uint32_t BlockSize>
	block_address
	block_manager<BlockSize>::get_nr_blocks() const
	{
		return bc_.get_nr_blocks();
	}

	template <uint32_t BlockSize>
	void
	block_manager<BlockSize>::prefetch(block_address b) const
	{
		bc_.prefetch(b);
	}

	template <uint32_t BlockSize>
	void
	block_manager<BlockSize>::flush() const
	{
		bc_.flush();
	}
}

//----------------------------------------------------------------