538 lines
13 KiB
C++
538 lines
13 KiB
C++
// Copyright (C) 2011 Red Hat, Inc. All rights reserved.
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//
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// This file is part of the thin-provisioning-tools source.
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//
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// thin-provisioning-tools is free software: you can redistribute it
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// and/or modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation, either version 3 of
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// the License, or (at your option) any later version.
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//
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// thin-provisioning-tools is distributed in the hope that it will be
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// useful, but WITHOUT ANY WARRANTY; without even the implied warranty
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// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License along
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// with thin-provisioning-tools. If not, see
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// <http://www.gnu.org/licenses/>.
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#include "block.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <string.h>
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#include <boost/bind.hpp>
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#include <stdexcept>
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#include <sstream>
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//----------------------------------------------------------------
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// FIXME: give this namesace a name
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namespace {
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using namespace std;
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int const DEFAULT_MODE = 0666;
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// FIXME: these will slow it down until we start doing async io.
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int const OPEN_FLAGS = O_DIRECT | O_SYNC;
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// FIXME: introduce a new exception for this, or at least lift this
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// to exception.h
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void syscall_failed(char const *call) {
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char buffer[128];
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char *msg = strerror_r(errno, buffer, sizeof(buffer));
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ostringstream out;
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out << "syscall '" << call << "' failed: " << msg;
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throw runtime_error(out.str());
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}
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int open_file(string const &path, int flags) {
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int fd = ::open(path.c_str(), OPEN_FLAGS | flags, DEFAULT_MODE);
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if (fd < 0)
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syscall_failed("open");
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return fd;
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}
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bool file_exists(string const &path) {
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struct ::stat info;
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int r = ::stat(path.c_str(), &info);
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if (r) {
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if (errno == ENOENT)
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return false;
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syscall_failed("stat");
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return false; // never get here
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} else
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return S_ISREG(info.st_mode) || S_ISBLK(info.st_mode);
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}
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int create_block_file(string const &path, off_t file_size) {
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if (file_exists(path)) {
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ostringstream out;
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out << __FUNCTION__ << ": file '" << path << "' already exists";
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throw runtime_error(out.str());
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}
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int fd = open_file(path, O_CREAT | O_RDWR);
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// fallocate didn't seem to work
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int r = ::lseek(fd, file_size, SEEK_SET);
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if (r < 0)
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syscall_failed("lseek");
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return fd;
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}
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int open_block_file(string const &path, off_t min_size, bool writeable) {
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if (!file_exists(path)) {
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ostringstream out;
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out << __FUNCTION__ << ": file '" << path << "' doesn't exist";
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throw runtime_error(out.str());
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}
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return open_file(path, writeable ? O_RDWR : O_RDONLY);
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}
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};
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namespace persistent_data {
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template <uint32_t BlockSize>
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block_io<BlockSize>::block_io(std::string const &path, block_address nr_blocks, mode m)
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: nr_blocks_(nr_blocks),
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mode_(m)
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{
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off_t file_size = nr_blocks * BlockSize;
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switch (m) {
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case READ_ONLY:
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fd_ = open_block_file(path, file_size, false);
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break;
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case READ_WRITE:
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fd_ = open_block_file(path, file_size, true);
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break;
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case CREATE:
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fd_ = create_block_file(path, file_size);
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break;
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default:
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throw runtime_error("unsupported mode");
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}
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}
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template <uint32_t BlockSize>
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block_io<BlockSize>::~block_io()
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{
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if (::close(fd_) < 0)
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syscall_failed("close");
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}
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template <uint32_t BlockSize>
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void
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block_io<BlockSize>::read_buffer(block_address location, buffer<BlockSize> &buffer) const
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{
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off_t r;
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r = ::lseek(fd_, BlockSize * location, SEEK_SET);
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if (r == (off_t) -1)
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throw std::runtime_error("lseek failed");
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ssize_t n;
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size_t remaining = BlockSize;
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unsigned char *buf = buffer.raw();
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do {
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n = ::read(fd_, buf, remaining);
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if (n > 0) {
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remaining -= n;
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buf += n;
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}
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} while (remaining && ((n > 0) || (n == EINTR) || (n == EAGAIN)));
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if (n < 0)
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throw std::runtime_error("read failed");
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}
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template <uint32_t BlockSize>
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void
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block_io<BlockSize>::write_buffer(block_address location, buffer<BlockSize> const &buffer)
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{
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off_t r;
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r = ::lseek(fd_, BlockSize * location, SEEK_SET);
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if (r == (off_t) -1)
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throw std::runtime_error("lseek failed");
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ssize_t n;
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size_t remaining = BlockSize;
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unsigned char const *buf = buffer.raw();
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do {
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n = ::write(fd_, buf, remaining);
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if (n > 0) {
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remaining -= n;
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buf += n;
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}
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} while (remaining && ((n > 0) || (n == EINTR) || (n == EAGAIN)));
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if (n < 0) {
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std::ostringstream out;
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out << "write failed to block " << location
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<< ", block size = " << BlockSize
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<< ", remaining = " << remaining
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<< ", n = " << n
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<< ", errno = " << errno
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<< ", fd_ = " << fd_
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<< std::endl;
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throw std::runtime_error(out.str());
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}
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}
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//----------------------------------------------------------------
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template <uint32_t BlockSize>
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block_manager<BlockSize>::block::block(typename block_io<BlockSize>::ptr io,
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block_address location,
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block_type bt,
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typename validator::ptr v,
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bool zero)
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: io_(io),
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location_(location),
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data_(new buffer<BlockSize>()),
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validator_(v),
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bt_(bt),
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dirty_(false)
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{
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if (zero) {
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// FIXME: duplicate memset
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memset(data_->raw(), 0, BlockSize);
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dirty_ = true; // redundant?
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} else {
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io_->read_buffer(location_, *data_);
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validator_->check(*data_, location_);
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}
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}
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template <uint32_t BlockSize>
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block_manager<BlockSize>::block::~block()
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{
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flush();
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}
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template <uint32_t BlockSize>
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void
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block_manager<BlockSize>::block::flush()
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{
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if (dirty_) {
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validator_->prepare(*data_, location_);
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io_->write_buffer(location_, *data_);
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dirty_ = false;
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}
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}
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template <uint32_t BlockSize>
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void
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block_manager<BlockSize>::block::change_validator(typename block_manager<BlockSize>::validator::ptr v,
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bool check)
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{
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if (v.get() != validator_.get()) {
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if (dirty_)
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// It may have already happened, by calling
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// this we ensure we're consistent.
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validator_->prepare(*data_, location_);
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validator_ = v;
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if (check)
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validator_->check(*data_, location_);
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}
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}
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//----------------------------------------------------------------
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template <uint32_t BlockSize>
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block_manager<BlockSize>::read_ref::read_ref(block_manager<BlockSize> const &bm,
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typename block::ptr b)
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: bm_(&bm),
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block_(b),
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holders_(new unsigned)
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{
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*holders_ = 1;
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}
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template <uint32_t BlockSize>
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block_manager<BlockSize>::read_ref::read_ref(read_ref const &rhs)
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: bm_(rhs.bm_),
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block_(rhs.block_),
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holders_(rhs.holders_)
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{
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(*holders_)++;
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}
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template <uint32_t BlockSize>
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block_manager<BlockSize>::read_ref::~read_ref()
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{
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if (!--(*holders_)) {
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if (block_->bt_ == BT_SUPERBLOCK) {
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bm_->flush();
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bm_->cache_.put(block_);
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bm_->flush();
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} else
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bm_->cache_.put(block_);
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bm_->tracker_.unlock(block_->location_);
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delete holders_;
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}
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}
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template <uint32_t BlockSize>
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typename block_manager<BlockSize>::read_ref const &
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block_manager<BlockSize>::read_ref::operator =(read_ref const &rhs)
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{
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if (this != &rhs) {
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block_ = rhs.block_;
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bm_ = rhs.bm_;
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holders_ = rhs.holders_;
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(*holders_)++;
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}
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return *this;
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}
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template <uint32_t BlockSize>
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block_address
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block_manager<BlockSize>::read_ref::get_location() const
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{
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return block_->location_;
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}
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template <uint32_t BlockSize>
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buffer<BlockSize> const &
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block_manager<BlockSize>::read_ref::data() const
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{
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return *block_->data_;
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}
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//--------------------------------
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template <uint32_t BlockSize>
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block_manager<BlockSize>::write_ref::write_ref(block_manager<BlockSize> const &bm,
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typename block::ptr b)
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: read_ref(bm, b)
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{
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b->dirty_ = true;
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}
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template <uint32_t BlockSize>
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buffer<BlockSize> &
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block_manager<BlockSize>::write_ref::data()
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{
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return *read_ref::block_->data_;
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}
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//----------------------------------------------------------------
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template <uint32_t BlockSize>
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block_manager<BlockSize>::block_manager(std::string const &path,
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block_address nr_blocks,
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unsigned max_concurrent_blocks,
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typename block_io<BlockSize>::mode mode)
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: io_(new block_io<BlockSize>(path, nr_blocks, mode)),
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cache_(max(1024u, max_concurrent_blocks)),
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tracker_(0, nr_blocks)
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{
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}
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template <uint32_t BlockSize>
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typename block_manager<BlockSize>::read_ref
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block_manager<BlockSize>::read_lock(block_address location,
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typename block_manager<BlockSize>::validator::ptr v) const
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{
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tracker_.read_lock(location);
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try {
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check(location);
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boost::optional<typename block::ptr> cached_block = cache_.get(location);
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if (cached_block) {
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typename block::ptr cb = *cached_block;
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cb->check_read_lockable();
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cb->change_validator(v);
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return read_ref(*this, *cached_block);
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}
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typename block::ptr b(new block(io_, location, BT_NORMAL, v));
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cache_.insert(b);
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return read_ref(*this, b);
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} catch (...) {
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tracker_.unlock(location);
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throw;
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}
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}
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template <uint32_t BlockSize>
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typename block_manager<BlockSize>::write_ref
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block_manager<BlockSize>::write_lock(block_address location,
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typename block_manager<BlockSize>::validator::ptr v)
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{
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tracker_.write_lock(location);
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try {
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check(location);
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boost::optional<typename block::ptr> cached_block = cache_.get(location);
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if (cached_block) {
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typename block::ptr cb = *cached_block;
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cb->check_write_lockable();
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cb->change_validator(v);
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return write_ref(*this, *cached_block);
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}
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typename block::ptr b(new block(io_, location, BT_NORMAL, v));
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cache_.insert(b);
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return write_ref(*this, b);
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} catch (...) {
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tracker_.unlock(location);
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throw;
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}
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}
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template <uint32_t BlockSize>
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typename block_manager<BlockSize>::write_ref
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block_manager<BlockSize>::write_lock_zero(block_address location,
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typename block_manager<BlockSize>::validator::ptr v)
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{
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tracker_.write_lock(location);
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try {
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check(location);
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boost::optional<typename block::ptr> cached_block = cache_.get(location);
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if (cached_block) {
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typename block::ptr cb = *cached_block;
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cb->check_write_lockable();
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cb->change_validator(v, false);
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memset((*cached_block)->data_->raw(), 0, BlockSize);
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return write_ref(*this, *cached_block);
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}
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typename block::ptr b(new block(io_, location, BT_NORMAL, v, true));
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cache_.insert(b);
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return write_ref(*this, b);
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} catch (...) {
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tracker_.unlock(location);
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throw;
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}
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}
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template <uint32_t BlockSize>
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typename block_manager<BlockSize>::write_ref
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block_manager<BlockSize>::superblock(block_address location,
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typename block_manager<BlockSize>::validator::ptr v)
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{
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tracker_.superblock_lock(location);
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try {
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check(location);
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boost::optional<typename block::ptr> cached_block = cache_.get(location);
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if (cached_block) {
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typename block::ptr cb = *cached_block;
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cb->check_write_lockable();
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cb->bt_ = BT_SUPERBLOCK;
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cb->change_validator(v);
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return write_ref(*this, *cached_block);
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}
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typename block::ptr b(new block(io_, location, BT_SUPERBLOCK, v));
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cache_.insert(b);
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return write_ref(*this, b);
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} catch (...) {
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tracker_.unlock(location);
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throw;
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}
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}
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template <uint32_t BlockSize>
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typename block_manager<BlockSize>::write_ref
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block_manager<BlockSize>::superblock_zero(block_address location,
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typename block_manager<BlockSize>::validator::ptr v)
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{
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tracker_.superblock_lock(location);
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try {
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check(location);
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boost::optional<typename block::ptr> cached_block = cache_.get(location);
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if (cached_block) {
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typename block::ptr cb = *cached_block;
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cb->check_write_lockable();
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cb->bt_ = BT_SUPERBLOCK;
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cb->change_validator(v, false);
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memset(cb->data_->raw(), 0, BlockSize); // FIXME: add a zero method to buffer
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return write_ref(*this, *cached_block);
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}
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typename block::ptr b(new block(io_, location, BT_SUPERBLOCK, v, true));
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cache_.insert(b);
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return write_ref(*this, b);
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} catch (...) {
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tracker_.unlock(location);
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throw;
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}
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}
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template <uint32_t BlockSize>
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void
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block_manager<BlockSize>::check(block_address b) const
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{
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if (b >= io_->get_nr_blocks())
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throw std::runtime_error("block address out of bounds");
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}
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template <uint32_t BlockSize>
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block_address
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block_manager<BlockSize>::get_nr_blocks() const
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{
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return io_->get_nr_blocks();
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}
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template <uint32_t BlockSize>
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void
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block_manager<BlockSize>::write_block(typename block::ptr b) const
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{
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b->flush();
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}
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template <uint32_t BlockSize>
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void
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block_manager<BlockSize>::flush() const
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{
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cache_.iterate_unheld(
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boost::bind(&block_manager<BlockSize>::write_block, this, _1));
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}
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template <uint32_t BlockSize>
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bool
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block_manager<BlockSize>::is_locked(block_address b) const
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{
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return tracker_.is_locked(b);
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}
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}
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//----------------------------------------------------------------
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