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[block-cache] fix potential file descriptor leak

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Encapsulate file descriptor into an object, to ensure that an fd will be
closed properly while exception raised, e.g., the block_cache throws
exception during the block_manager's construction.
This commit is contained in:
Ming-Hung Tsai
2020-02-22 17:37:22 +08:00
parent c85ea5ef76
commit 955e11bc28
9 changed files with 42 additions and 32 deletions
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28
base/file_utils.cc
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@@ -39,14 +39,16 @@ namespace {
//----------------------------------------------------------------
int
file_utils::open_file(string const &path, int flags) {
int fd = ::open(path.c_str(), OPEN_FLAGS | flags, DEFAULT_MODE);
if (fd < 0)
file_utils::file_descriptor::file_descriptor(string const &path, int flags) {
fd_ = ::open(path.c_str(), OPEN_FLAGS | flags, DEFAULT_MODE);
if (fd_ < 0)
syscall_failed("open",
"Note: you cannot run this tool with these options on live metadata.");
}
return fd;
file_utils::file_descriptor::~file_descriptor() {
close(fd_);
fd_ = -1;
}
bool
@@ -76,7 +78,7 @@ file_utils::check_file_exists(string const &file, bool must_be_regular_file) {
throw runtime_error("Not a regular file");
}
int
file_utils::file_descriptor
file_utils::create_block_file(string const &path, off_t file_size) {
if (file_exists(path)) {
ostringstream out;
@@ -84,16 +86,16 @@ file_utils::create_block_file(string const &path, off_t file_size) {
throw runtime_error(out.str());
}
int fd = open_file(path, O_CREAT | O_EXCL | O_RDWR);
file_descriptor fd(path, O_CREAT | O_EXCL | O_RDWR);
int r = ::ftruncate(fd, file_size);
int r = ::ftruncate(fd.fd_, file_size);
if (r < 0)
syscall_failed("ftruncate");
return fd;
}
int
file_utils::file_descriptor
file_utils::open_block_file(string const &path, off_t min_size, bool writeable, bool excl) {
if (!file_exists(path)) {
ostringstream out;
@@ -105,7 +107,7 @@ file_utils::open_block_file(string const &path, off_t min_size, bool writeable,
if (excl)
flags |= O_EXCL;
return open_file(path, flags);
return file_descriptor(path, flags);
}
uint64_t
@@ -146,17 +148,15 @@ file_utils::zero_superblock(std::string const &path)
{
char *buffer;
unsigned const SUPERBLOCK_SIZE = 4096;
int fd = open_block_file(path, SUPERBLOCK_SIZE, true, true);
file_descriptor fd = open_block_file(path, SUPERBLOCK_SIZE, true, true);
buffer = reinterpret_cast<char *>(aligned_alloc(SUPERBLOCK_SIZE, SUPERBLOCK_SIZE));
if (!buffer)
throw runtime_error("out of memory");
memset(buffer, 0, SUPERBLOCK_SIZE);
if (::write(fd, buffer, SUPERBLOCK_SIZE) != SUPERBLOCK_SIZE)
if (::write(fd.fd_, buffer, SUPERBLOCK_SIZE) != SUPERBLOCK_SIZE)
throw runtime_error("couldn't zero superblock");
::close(fd);
}
//----------------------------------------------------------------

15
base/file_utils.h
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@@ -8,11 +8,20 @@
//----------------------------------------------------------------
namespace file_utils {
int open_file(std::string const &path, int flags);
struct file_descriptor {
// file_descriptor is movable but not copyable
file_descriptor(file_descriptor &&) = default;
file_descriptor& operator=(file_descriptor &&) = default;
file_descriptor(std::string const &path, int flags);
virtual ~file_descriptor();
int fd_;
};
bool file_exists(std::string const &path);
void check_file_exists(std::string const &file, bool must_be_regular_file = true);
int create_block_file(std::string const &path, off_t file_size);
int open_block_file(std::string const &path, off_t min_size, bool writeable, bool excl = true);
file_descriptor create_block_file(std::string const &path, off_t file_size);
file_descriptor open_block_file(std::string const &path, off_t min_size, bool writeable, bool excl = true);
uint64_t get_file_length(std::string const &file);
void zero_superblock(std::string const &path);
}

11
block-cache/block_cache.cc
View File

@@ -15,6 +15,7 @@
#include <sstream>
using namespace bcache;
using namespace file_utils;
//----------------------------------------------------------------
@@ -290,7 +291,7 @@ block_cache::setup_control_block(block &b)
size_t block_size_bytes = block_size_ << SECTOR_SHIFT;
memset(cb, 0, sizeof(*cb));
cb->aio_fildes = fd_;
cb->aio_fildes = fd_.fd_;
cb->u.c.buf = b.data_;
cb->u.c.offset = block_size_bytes * b.index_;
@@ -371,8 +372,9 @@ block_cache::calc_nr_buckets(unsigned nr_blocks)
return r;
}
block_cache::block_cache(int fd, sector_t block_size, uint64_t on_disk_blocks, size_t mem)
: nr_locked_(0),
block_cache::block_cache(file_descriptor &fd, sector_t block_size, uint64_t on_disk_blocks, size_t mem)
: fd_(fd),
nr_locked_(0),
nr_dirty_(0),
nr_io_pending_(0),
read_hits_(0),
@@ -386,7 +388,6 @@ block_cache::block_cache(int fd, sector_t block_size, uint64_t on_disk_blocks, s
int r;
unsigned nr_cache_blocks = calc_nr_cache_blocks(mem, block_size);
fd_ = fd;
block_size_ = block_size;
nr_data_blocks_ = on_disk_blocks;
nr_cache_blocks_ = nr_cache_blocks;
@@ -418,8 +419,6 @@ block_cache::~block_cache()
if (aio_context_)
io_destroy(aio_context_);
::close(fd_);
#if 0
std::cerr << "\nblock cache stats\n"
<< "=================\n"

5
block-cache/block_cache.h
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@@ -2,6 +2,7 @@
#define BLOCK_CACHE_H
#include "base/container_of.h"
#include "base/file_utils.h"
#include <boost/intrusive/list.hpp>
#include <boost/intrusive/set.hpp>
@@ -185,7 +186,7 @@ namespace bcache {
//--------------------------------
block_cache(int fd, sector_t block_size,
block_cache(file_utils::file_descriptor &fd, sector_t block_size,
uint64_t max_nr_blocks, size_t mem);
~block_cache();
@@ -247,7 +248,7 @@ namespace bcache {
//--------------------------------
int fd_;
file_utils::file_descriptor &fd_;
sector_t block_size_;
uint64_t nr_data_blocks_;
uint64_t nr_cache_blocks_;

7
persistent-data/block.h
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@@ -136,11 +136,12 @@ namespace persistent_data {
private:
uint64_t choose_cache_size(block_address nr_blocks) const;
int open_or_create_block_file(std::string const &path, off_t file_size,
mode m, bool excl);
file_utils::file_descriptor open_or_create_block_file(std::string const &path,
off_t file_size,
mode m, bool excl);
void check(block_address b) const;
int fd_;
file_utils::file_descriptor fd_;
mutable block_cache bc_;
unsigned superblock_ref_count_;
};

2
persistent-data/block.tcc
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@@ -154,7 +154,7 @@ namespace persistent_data {
}
template <uint32_t BlockSize>
int
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) {

2
thin-provisioning/cache_stream.cc
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@@ -18,7 +18,7 @@ cache_stream::cache_stream(string const &path,
// hack because cache uses LRU rather than MRU
cache_blocks_((cache_mem / block_size) / 2u),
fd_(file_utils::open_file(path, O_RDONLY | O_EXCL)),
fd_(path, O_RDONLY | O_EXCL),
v_(new bcache::noop_validator()),
cache_(new block_cache(fd_, block_size / 512, nr_blocks_, cache_mem)),
current_index_(0) {

2
thin-provisioning/cache_stream.h
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@@ -38,7 +38,7 @@ namespace thin_provisioning {
block_address nr_blocks_;
block_address cache_blocks_;
int fd_;
file_utils::file_descriptor fd_;
validator::ptr v_;
std::unique_ptr<block_cache> cache_;

2
unit-tests/bcache_t.cc
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@@ -38,7 +38,7 @@ TEST(BCacheTests, cleaned_on_demand)
unsigned const NR_BLOCKS = 16;
temp_file tmp("bcache_t", 1);
int fd = open(tmp.get_path().c_str(), O_RDWR | O_DIRECT, 0666);
file_utils::file_descriptor fd(tmp.get_path().c_str(), O_RDWR | O_DIRECT);
uint64_t bs = 8;
block_cache bc(fd, bs, 64, (bs << SECTOR_SHIFT) * NR_BLOCKS);