fix race condition in part_file

This commit is contained in:
arvidn 2018-06-18 17:40:07 +02:00 committed by Arvid Norberg
parent 81ce7aa4ab
commit 4ae262d2d4
3 changed files with 36 additions and 18 deletions

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@ -1,5 +1,5 @@
* fix race condition during part_file export * fix race condition in part_file
* fix part_file open mode compatibility test * fix part_file open mode compatibility test
* fixed race condition in random number generator * fixed race condition in random number generator
* fix race condition in stat_cache (disk storage) * fix race condition in stat_cache (disk storage)

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@ -115,7 +115,9 @@ namespace libtorrent
boost::unordered_map<int, int> m_piece_map; boost::unordered_map<int, int> m_piece_map;
// this is the file handle to the part file // this is the file handle to the part file
file m_file; // it's allocated on the heap and reference counted, to allow it to be
// closed and re-opened while other threads are still using it
boost::shared_ptr<file> m_file;
}; };
} }

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@ -94,13 +94,13 @@ namespace libtorrent
error_code ec; error_code ec;
std::string fn = combine_path(m_path, m_name); std::string fn = combine_path(m_path, m_name);
m_file.open(fn, file::read_only, ec); boost::shared_ptr<file> const f = boost::make_shared<file>(fn, file::read_only, boost::ref(ec));
if (!ec) if (!ec)
{ {
// parse header // parse header
boost::scoped_array<boost::uint32_t> header(new boost::uint32_t[m_header_size / 4]); boost::scoped_array<boost::uint32_t> header(new boost::uint32_t[m_header_size / 4]);
file::iovec_t b = {header.get(), size_t(m_header_size) }; file::iovec_t b = {header.get(), size_t(m_header_size) };
int n = m_file.readv(0, &b, 1, ec); int const n = f->readv(0, &b, 1, ec);
if (ec) return; if (ec) return;
// we don't have a full header. consider the file empty // we don't have a full header. consider the file empty
@ -142,8 +142,7 @@ namespace libtorrent
{ {
if (free_slots[i]) m_free_slots.push_back(i); if (free_slots[i]) m_free_slots.push_back(i);
} }
m_file = f;
m_file.close();
} }
} }
@ -186,8 +185,9 @@ namespace libtorrent
boost::unordered_map<int, int>::iterator const i = m_piece_map.find(piece); boost::unordered_map<int, int>::iterator const i = m_piece_map.find(piece);
int const slot = i == m_piece_map.end() ? allocate_slot(piece) : i->second; int const slot = i == m_piece_map.end() ? allocate_slot(piece) : i->second;
boost::shared_ptr<file> const f = m_file;
l.unlock(); l.unlock();
return m_file.writev(slot_offset(slot) + offset, bufs, num_bufs, ec); return f->writev(slot_offset(slot) + offset, bufs, num_bufs, ec);
} }
int part_file::readv(file::iovec_t const* bufs, int num_bufs int part_file::readv(file::iovec_t const* bufs, int num_bufs
@ -205,21 +205,25 @@ namespace libtorrent
int const slot = i->second; int const slot = i->second;
open_file(file::read_write | file::attribute_hidden, ec); open_file(file::read_only | file::attribute_hidden, ec);
if (ec) return -1; if (ec) return -1;
boost::shared_ptr<file> const f = m_file;
l.unlock(); l.unlock();
return m_file.readv(slot_offset(slot) + offset, bufs, num_bufs, ec); return f->readv(slot_offset(slot) + offset, bufs, num_bufs, ec);
} }
void part_file::open_file(int mode, error_code& ec) void part_file::open_file(int mode, error_code& ec)
{ {
if (m_file.is_open() && ((mode & file::rw_mask) == file::read_only TORRENT_ASSERT((mode & file::lock_file) == 0);
|| (m_file.open_mode() & file::rw_mask) == file::read_write))
if (m_file && m_file->is_open()
&& ((mode & file::rw_mask) == file::read_only
|| (m_file->open_mode() & file::rw_mask) == file::read_write))
return; return;
std::string const fn = combine_path(m_path, m_name); std::string const fn = combine_path(m_path, m_name);
m_file.open(fn, mode, ec); boost::shared_ptr<file> f = boost::make_shared<file>(fn, mode, boost::ref(ec));
if (((mode & file::rw_mask) != file::read_only) if (((mode & file::rw_mask) != file::read_only)
&& ec == boost::system::errc::no_such_file_or_directory) && ec == boost::system::errc::no_such_file_or_directory)
{ {
@ -229,8 +233,9 @@ namespace libtorrent
create_directories(m_path, ec); create_directories(m_path, ec);
if (ec) return; if (ec) return;
m_file.open(fn, mode, ec); f = boost::make_shared<file>(fn, mode, boost::ref(ec));
} }
if (!ec) m_file = f;
} }
void part_file::free_piece(int piece) void part_file::free_piece(int piece)
@ -257,7 +262,10 @@ namespace libtorrent
flush_metadata_impl(ec); flush_metadata_impl(ec);
if (ec) return; if (ec) return;
m_file.close(); // we're only supposed to move part files from a fence job. i.e. no other
// disk jobs are supposed to be in-flight at this point
TORRENT_ASSERT(!m_file || m_file.unique());
m_file.reset();
if (!m_piece_map.empty()) if (!m_piece_map.empty())
{ {
@ -310,12 +318,16 @@ namespace libtorrent
{ {
int const slot = i->second; int const slot = i->second;
open_file(file::read_only, ec); open_file(file::read_only, ec);
boost::shared_ptr<file> const local_file = m_file;
if (ec) return; if (ec) return;
if (!buf) buf.reset(new char[m_piece_size]); if (!buf) buf.reset(new char[m_piece_size]);
// don't hold the lock during disk I/O
l.unlock();
file::iovec_t v = { buf.get(), size_t(block_to_copy) }; file::iovec_t v = { buf.get(), size_t(block_to_copy) };
v.iov_len = m_file.readv(slot_offset(slot) + piece_offset, &v, 1, ec); v.iov_len = local_file->readv(slot_offset(slot) + piece_offset, &v, 1, ec);
TORRENT_ASSERT(!ec); TORRENT_ASSERT(!ec);
if (ec || v.iov_len == 0) return; if (ec || v.iov_len == 0) return;
@ -323,6 +335,10 @@ namespace libtorrent
TORRENT_ASSERT(ec || ret == v.iov_len); TORRENT_ASSERT(ec || ret == v.iov_len);
if (ec || ret != v.iov_len) return; if (ec || ret != v.iov_len) return;
// we're done with the disk I/O, grab the lock again to update
// the slot map
l.lock();
if (block_to_copy == m_piece_size) if (block_to_copy == m_piece_size)
{ {
// since we released the lock, it's technically possible that // since we released the lock, it's technically possible that
@ -362,11 +378,11 @@ namespace libtorrent
if (m_piece_map.empty()) if (m_piece_map.empty())
{ {
m_file.close(); m_file.reset();
// if we don't have any pieces left in the // if we don't have any pieces left in the
// part file, remove it // part file, remove it
std::string p = combine_path(m_path, m_name); std::string const p = combine_path(m_path, m_name);
remove(p, ec); remove(p, ec);
if (ec == boost::system::errc::no_such_file_or_directory) if (ec == boost::system::errc::no_such_file_or_directory)
@ -400,7 +416,7 @@ namespace libtorrent
VALGRIND_CHECK_MEM_IS_DEFINED(header.get(), m_header_size); VALGRIND_CHECK_MEM_IS_DEFINED(header.get(), m_header_size);
#endif #endif
file::iovec_t b = {header.get(), size_t(m_header_size) }; file::iovec_t b = {header.get(), size_t(m_header_size) };
m_file.writev(0, &b, 1, ec); m_file->writev(0, &b, 1, ec);
if (ec) return; if (ec) return;
} }
} }