hardcoresushi/libcryfs
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Fix deadlock

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This commit is contained in:
Sebastian Messmer 2018-12-26 15:12:01 +01:00
parent fb792ec353
commit 2449cc0790
2 changed files with 33 additions and 22 deletions
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52
src/cryfs/filesystem/fsblobstore/DirBlob.cpp
View File

@ -29,18 +29,18 @@ namespace fsblobstore {
constexpr off_t DirBlob::DIR_LSTAT_SIZE;
DirBlob::DirBlob(FsBlobStore *fsBlobStore, unique_ref<Blob> blob, std::function<off_t (const blockstore::Key&)> getLstatSize) :
FsBlob(std::move(blob)), _fsBlobStore(fsBlobStore), _getLstatSize(getLstatSize), _entries(), _mutex(), _changed(false) {
FsBlob(std::move(blob)), _fsBlobStore(fsBlobStore), _getLstatSize(getLstatSize), _getLstatSizeMutex(), _entries(), _entriesAndChangedMutex(), _changed(false) {
ASSERT(baseBlob().blobType() == FsBlobView::BlobType::DIR, "Loaded blob is not a directory");
_readEntriesFromBlob();
}
DirBlob::~DirBlob() {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
_writeEntriesToBlob();
}
void DirBlob::flush() {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
_writeEntriesToBlob();
baseBlob().flush();
}
@ -66,17 +66,17 @@ void DirBlob::_readEntriesFromBlob() {
}
void DirBlob::AddChildDir(const std::string &name, const Key &blobKey, mode_t mode, uid_t uid, gid_t gid, timespec lastAccessTime, timespec lastModificationTime) {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
_addChild(name, blobKey, fspp::Dir::EntryType::DIR, mode, uid, gid, lastAccessTime, lastModificationTime);
}
void DirBlob::AddChildFile(const std::string &name, const Key &blobKey, mode_t mode, uid_t uid, gid_t gid, timespec lastAccessTime, timespec lastModificationTime) {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
_addChild(name, blobKey, fspp::Dir::EntryType::FILE, mode, uid, gid, lastAccessTime, lastModificationTime);
}
void DirBlob::AddChildSymlink(const std::string &name, const blockstore::Key &blobKey, uid_t uid, gid_t gid, timespec lastAccessTime, timespec lastModificationTime) {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
_addChild(name, blobKey, fspp::Dir::EntryType::SYMLINK, S_IFLNK | S_IRUSR | S_IWUSR | S_IXUSR | S_IRGRP | S_IWGRP | S_IXGRP | S_IROTH | S_IWOTH | S_IXOTH, uid, gid, lastAccessTime, lastModificationTime);
}
@ -89,41 +89,41 @@ void DirBlob::_addChild(const std::string &name, const Key &blobKey,
void DirBlob::AddOrOverwriteChild(const std::string &name, const Key &blobKey, fspp::Dir::EntryType entryType,
mode_t mode, uid_t uid, gid_t gid, timespec lastAccessTime, timespec lastModificationTime,
std::function<void (const blockstore::Key &key)> onOverwritten) {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
_entries.addOrOverwrite(name, blobKey, entryType, mode, uid, gid, lastAccessTime, lastModificationTime, onOverwritten);
_changed = true;
}
void DirBlob::RenameChild(const blockstore::Key &key, const std::string &newName, std::function<void (const blockstore::Key &key)> onOverwritten) {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
_entries.rename(key, newName, onOverwritten);
_changed = true;
}
boost::optional<const DirEntry&> DirBlob::GetChild(const string &name) const {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
return _entries.get(name);
}
boost::optional<const DirEntry&> DirBlob::GetChild(const Key &key) const {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
return _entries.get(key);
}
void DirBlob::RemoveChild(const string &name) {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
_entries.remove(name);
_changed = true;
}
void DirBlob::RemoveChild(const Key &key) {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
_entries.remove(key);
_changed = true;
}
void DirBlob::AppendChildrenTo(vector<fspp::Dir::Entry> *result) const {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
result->reserve(result->size() + _entries.size());
for (const auto &entry : _entries) {
result->emplace_back(entry.type(), entry.name());
@ -135,7 +135,17 @@ off_t DirBlob::lstat_size() const {
}
void DirBlob::statChild(const Key &key, struct ::stat *result) const {
result->st_size = _getLstatSize(key);
std::unique_lock<std::mutex> lock(_getLstatSizeMutex);
auto lstatSizeGetter = _getLstatSize;
// The following unlock is important to avoid deadlock.
// ParallelAccessFsBlobStore::load() causes a call to DirBlob::setLstatSizeGetter,
// so their lock ordering first locks the ParallelAccessStore::_mutex, then the DirBlob::_getLstatSizeMutex.
// this requires us to free DirBlob::_getLstatSizeMutex before calling into lstatSizeGetter(), because
// lstatSizeGetter can call ParallelAccessFsBlobStore::load().
lock.unlock();
result->st_size = lstatSizeGetter(key);
statChildWithSizeAlreadySet(key, result);
}
@ -159,43 +169,43 @@ void DirBlob::statChildWithSizeAlreadySet(const Key &key, struct ::stat *result)
}
void DirBlob::updateAccessTimestampForChild(const Key &key) {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
_entries.updateAccessTimestampForChild(key);
_changed = true;
}
void DirBlob::updateModificationTimestampForChild(const Key &key) {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
_entries.updateModificationTimestampForChild(key);
_changed = true;
}
void DirBlob::chmodChild(const Key &key, mode_t mode) {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
_entries.setMode(key, mode);
_changed = true;
}
void DirBlob::chownChild(const Key &key, uid_t uid, gid_t gid) {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
if(_entries.setUidGid(key, uid, gid)) {
_changed = true;
}
}
void DirBlob::utimensChild(const Key &key, timespec lastAccessTime, timespec lastModificationTime) {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
_entries.setAccessTimes(key, lastAccessTime, lastModificationTime);
_changed = true;
}
void DirBlob::setLstatSizeGetter(std::function<off_t(const blockstore::Key&)> getLstatSize) {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_getLstatSizeMutex);
_getLstatSize = getLstatSize;
}
cpputils::unique_ref<blobstore::Blob> DirBlob::releaseBaseBlob() {
std::unique_lock<std::mutex> lock(_mutex);
std::unique_lock<std::mutex> lock(_entriesAndChangedMutex);
_writeEntriesToBlob();
return FsBlob::releaseBaseBlob();
}

3
src/cryfs/filesystem/fsblobstore/DirBlob.h
View File

@ -82,8 +82,9 @@ namespace cryfs {
FsBlobStore *_fsBlobStore;
std::function<off_t (const blockstore::Key&)> _getLstatSize;
mutable std::mutex _getLstatSizeMutex;
DirEntryList _entries;
mutable std::mutex _mutex;
mutable std::mutex _entriesAndChangedMutex;
bool _changed;
DISALLOW_COPY_AND_ASSIGN(DirBlob);