thin-provisioning-tools/persistent-data/block.tcc
Joe Thornber e7816d2f43 [block] Open block files with O_DIRECT | O_SYNC.
Putting this back in.  Dumping metadata snapshots fails without.  So
there's more caching in the kernel than I expected.
2013-10-07 09:58:17 +01:00

538 lines
13 KiB
C++

// 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 <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <boost/bind.hpp>
#include <stdexcept>
#include <sstream>
//----------------------------------------------------------------
// FIXME: give this namesace a name
namespace {
using namespace std;
int const DEFAULT_MODE = 0666;
// FIXME: these will slow it down until we start doing async io.
int const OPEN_FLAGS = O_DIRECT | O_SYNC;
// FIXME: introduce a new exception for this, or at least lift this
// to exception.h
void syscall_failed(char const *call) {
char buffer[128];
char *msg = strerror_r(errno, buffer, sizeof(buffer));
ostringstream out;
out << "syscall '" << call << "' failed: " << msg;
throw runtime_error(out.str());
}
int open_file(string const &path, int flags) {
int fd = ::open(path.c_str(), OPEN_FLAGS | flags, DEFAULT_MODE);
if (fd < 0)
syscall_failed("open");
return fd;
}
bool file_exists(string const &path) {
struct ::stat info;
int r = ::stat(path.c_str(), &info);
if (r) {
if (errno == ENOENT)
return false;
syscall_failed("stat");
return false; // never get here
} else
return S_ISREG(info.st_mode) || S_ISBLK(info.st_mode);
}
int create_block_file(string const &path, off_t file_size) {
if (file_exists(path)) {
ostringstream out;
out << __FUNCTION__ << ": file '" << path << "' already exists";
throw runtime_error(out.str());
}
int fd = open_file(path, O_CREAT | O_RDWR);
// fallocate didn't seem to work
int r = ::lseek(fd, file_size, SEEK_SET);
if (r < 0)
syscall_failed("lseek");
return fd;
}
int open_block_file(string const &path, off_t min_size, bool writeable) {
if (!file_exists(path)) {
ostringstream out;
out << __FUNCTION__ << ": file '" << path << "' doesn't exist";
throw runtime_error(out.str());
}
return open_file(path, writeable ? O_RDWR : O_RDONLY);
}
};
namespace persistent_data {
template <uint32_t BlockSize>
block_io<BlockSize>::block_io(std::string const &path, block_address nr_blocks, mode m)
: nr_blocks_(nr_blocks),
mode_(m)
{
off_t file_size = nr_blocks * BlockSize;
switch (m) {
case READ_ONLY:
fd_ = open_block_file(path, file_size, false);
break;
case READ_WRITE:
fd_ = open_block_file(path, file_size, true);
break;
case CREATE:
fd_ = create_block_file(path, file_size);
break;
default:
throw runtime_error("unsupported mode");
}
}
template <uint32_t BlockSize>
block_io<BlockSize>::~block_io()
{
if (::close(fd_) < 0)
syscall_failed("close");
}
template <uint32_t BlockSize>
void
block_io<BlockSize>::read_buffer(block_address location, buffer<BlockSize> &buffer) const
{
off_t r;
r = ::lseek(fd_, BlockSize * location, SEEK_SET);
if (r == (off_t) -1)
throw std::runtime_error("lseek failed");
ssize_t n;
size_t remaining = BlockSize;
unsigned char *buf = buffer.raw();
do {
n = ::read(fd_, buf, remaining);
if (n > 0) {
remaining -= n;
buf += n;
}
} while (remaining && ((n > 0) || (n == EINTR) || (n == EAGAIN)));
if (n < 0)
throw std::runtime_error("read failed");
}
template <uint32_t BlockSize>
void
block_io<BlockSize>::write_buffer(block_address location, buffer<BlockSize> const &buffer)
{
off_t r;
r = ::lseek(fd_, BlockSize * location, SEEK_SET);
if (r == (off_t) -1)
throw std::runtime_error("lseek failed");
ssize_t n;
size_t remaining = BlockSize;
unsigned char const *buf = buffer.raw();
do {
n = ::write(fd_, buf, remaining);
if (n > 0) {
remaining -= n;
buf += n;
}
} while (remaining && ((n > 0) || (n == EINTR) || (n == EAGAIN)));
if (n < 0) {
std::ostringstream out;
out << "write failed to block " << location
<< ", block size = " << BlockSize
<< ", remaining = " << remaining
<< ", n = " << n
<< ", errno = " << errno
<< ", fd_ = " << fd_
<< std::endl;
throw std::runtime_error(out.str());
}
}
//----------------------------------------------------------------
template <uint32_t BlockSize>
block_manager<BlockSize>::block::block(typename block_io<BlockSize>::ptr io,
block_address location,
block_type bt,
typename validator::ptr v,
bool zero)
: io_(io),
location_(location),
data_(new buffer<BlockSize>()),
validator_(v),
bt_(bt),
dirty_(false)
{
if (zero) {
// FIXME: duplicate memset
memset(data_->raw(), 0, BlockSize);
dirty_ = true; // redundant?
} else {
io_->read_buffer(location_, *data_);
validator_->check(*data_, location_);
}
}
template <uint32_t BlockSize>
block_manager<BlockSize>::block::~block()
{
flush();
}
template <uint32_t BlockSize>
void
block_manager<BlockSize>::block::flush()
{
if (dirty_) {
validator_->prepare(*data_, location_);
io_->write_buffer(location_, *data_);
dirty_ = false;
}
}
template <uint32_t BlockSize>
void
block_manager<BlockSize>::block::change_validator(typename block_manager<BlockSize>::validator::ptr v,
bool check)
{
if (v.get() != validator_.get()) {
if (dirty_)
// It may have already happened, by calling
// this we ensure we're consistent.
validator_->prepare(*data_, location_);
validator_ = v;
if (check)
validator_->check(*data_, location_);
}
}
//----------------------------------------------------------------
template <uint32_t BlockSize>
block_manager<BlockSize>::read_ref::read_ref(block_manager<BlockSize> const &bm,
typename block::ptr b)
: bm_(&bm),
block_(b),
holders_(new unsigned)
{
*holders_ = 1;
}
template <uint32_t BlockSize>
block_manager<BlockSize>::read_ref::read_ref(read_ref const &rhs)
: bm_(rhs.bm_),
block_(rhs.block_),
holders_(rhs.holders_)
{
(*holders_)++;
}
template <uint32_t BlockSize>
block_manager<BlockSize>::read_ref::~read_ref()
{
if (!--(*holders_)) {
if (block_->bt_ == BT_SUPERBLOCK) {
bm_->flush();
bm_->cache_.put(block_);
bm_->flush();
} else
bm_->cache_.put(block_);
bm_->tracker_.unlock(block_->location_);
delete holders_;
}
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::read_ref const &
block_manager<BlockSize>::read_ref::operator =(read_ref const &rhs)
{
if (this != &rhs) {
block_ = rhs.block_;
bm_ = rhs.bm_;
holders_ = rhs.holders_;
(*holders_)++;
}
return *this;
}
template <uint32_t BlockSize>
block_address
block_manager<BlockSize>::read_ref::get_location() const
{
return block_->location_;
}
template <uint32_t BlockSize>
buffer<BlockSize> const &
block_manager<BlockSize>::read_ref::data() const
{
return *block_->data_;
}
//--------------------------------
template <uint32_t BlockSize>
block_manager<BlockSize>::write_ref::write_ref(block_manager<BlockSize> const &bm,
typename block::ptr b)
: read_ref(bm, b)
{
b->dirty_ = true;
}
template <uint32_t BlockSize>
buffer<BlockSize> &
block_manager<BlockSize>::write_ref::data()
{
return *read_ref::block_->data_;
}
//----------------------------------------------------------------
template <uint32_t BlockSize>
block_manager<BlockSize>::block_manager(std::string const &path,
block_address nr_blocks,
unsigned max_concurrent_blocks,
typename block_io<BlockSize>::mode mode)
: io_(new block_io<BlockSize>(path, nr_blocks, mode)),
cache_(max(64u, max_concurrent_blocks)),
tracker_(0, nr_blocks)
{
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::read_ref
block_manager<BlockSize>::read_lock(block_address location,
typename block_manager<BlockSize>::validator::ptr v) const
{
tracker_.read_lock(location);
try {
check(location);
boost::optional<typename block::ptr> cached_block = cache_.get(location);
if (cached_block) {
typename block::ptr cb = *cached_block;
cb->check_read_lockable();
cb->change_validator(v);
return read_ref(*this, *cached_block);
}
typename block::ptr b(new block(io_, location, BT_NORMAL, v));
cache_.insert(b);
return read_ref(*this, b);
} catch (...) {
tracker_.unlock(location);
throw;
}
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::write_ref
block_manager<BlockSize>::write_lock(block_address location,
typename block_manager<BlockSize>::validator::ptr v)
{
tracker_.write_lock(location);
try {
check(location);
boost::optional<typename block::ptr> cached_block = cache_.get(location);
if (cached_block) {
typename block::ptr cb = *cached_block;
cb->check_write_lockable();
cb->change_validator(v);
return write_ref(*this, *cached_block);
}
typename block::ptr b(new block(io_, location, BT_NORMAL, v));
cache_.insert(b);
return write_ref(*this, b);
} catch (...) {
tracker_.unlock(location);
throw;
}
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::write_ref
block_manager<BlockSize>::write_lock_zero(block_address location,
typename block_manager<BlockSize>::validator::ptr v)
{
tracker_.write_lock(location);
try {
check(location);
boost::optional<typename block::ptr> cached_block = cache_.get(location);
if (cached_block) {
typename block::ptr cb = *cached_block;
cb->check_write_lockable();
cb->change_validator(v, false);
memset((*cached_block)->data_->raw(), 0, BlockSize);
return write_ref(*this, *cached_block);
}
typename block::ptr b(new block(io_, location, BT_NORMAL, v, true));
cache_.insert(b);
return write_ref(*this, b);
} catch (...) {
tracker_.unlock(location);
throw;
}
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::write_ref
block_manager<BlockSize>::superblock(block_address location,
typename block_manager<BlockSize>::validator::ptr v)
{
tracker_.superblock_lock(location);
try {
check(location);
boost::optional<typename block::ptr> cached_block = cache_.get(location);
if (cached_block) {
typename block::ptr cb = *cached_block;
cb->check_write_lockable();
cb->bt_ = BT_SUPERBLOCK;
cb->change_validator(v);
return write_ref(*this, *cached_block);
}
typename block::ptr b(new block(io_, location, BT_SUPERBLOCK, v));
cache_.insert(b);
return write_ref(*this, b);
} catch (...) {
tracker_.unlock(location);
throw;
}
}
template <uint32_t BlockSize>
typename block_manager<BlockSize>::write_ref
block_manager<BlockSize>::superblock_zero(block_address location,
typename block_manager<BlockSize>::validator::ptr v)
{
tracker_.superblock_lock(location);
try {
check(location);
boost::optional<typename block::ptr> cached_block = cache_.get(location);
if (cached_block) {
typename block::ptr cb = *cached_block;
cb->check_write_lockable();
cb->bt_ = BT_SUPERBLOCK;
cb->change_validator(v, false);
memset(cb->data_->raw(), 0, BlockSize); // FIXME: add a zero method to buffer
return write_ref(*this, *cached_block);
}
typename block::ptr b(new block(io_, location, BT_SUPERBLOCK, v, true));
cache_.insert(b);
return write_ref(*this, b);
} catch (...) {
tracker_.unlock(location);
throw;
}
}
template <uint32_t BlockSize>
void
block_manager<BlockSize>::check(block_address b) const
{
if (b >= io_->get_nr_blocks())
throw std::runtime_error("block address out of bounds");
}
template <uint32_t BlockSize>
block_address
block_manager<BlockSize>::get_nr_blocks() const
{
return io_->get_nr_blocks();
}
template <uint32_t BlockSize>
void
block_manager<BlockSize>::write_block(typename block::ptr b) const
{
b->flush();
}
template <uint32_t BlockSize>
void
block_manager<BlockSize>::flush() const
{
cache_.iterate_unheld(
boost::bind(&block_manager<BlockSize>::write_block, this, _1));
}
template <uint32_t BlockSize>
bool
block_manager<BlockSize>::is_locked(block_address b) const
{
return tracker_.is_locked(b);
}
}
//----------------------------------------------------------------