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https://github.com/facebook/sapling.git
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3b9a0310a1
Summary: If TreeInode::startLoadingInode() is in progress, and EdenServer::startTakeoverShutdown() is called, edenfs can deadlock: 1. Thread A: A FUSE request calls TreeInode::readdir() -> TreeInode::prefetch() -> TreeInode::startLoadingInode() on the children TreeInode-s -> RocksDbLocalStore::getFuture(). 2. Thread B: A takeover request calls EdenServer::performTakeoverShutdown() -> InodeMap::shutdown(). 3. Thread C: RocksDbLocalStore::getFuture() (called in step 1) completes -> TreeInode::inodeLoadComplete(). (The inodeLoadComplete continuation was registered by TreeInode::registerInodeLoadComplete().) 4. Thread C: After TreeInode::inodeLoadComplete() returns, the TreeInode's InodePtr is destructed, dropping the reference count to 0. 5. Thread C: InodeMap::onInodeUnreferenced() -> InodeMap::shutdownComplete() -> EdenMount::shutdown() (called in step 2) completes -> EdenServer::performTakeoverShutdown(). 6. Thread C: EdenServer::performTakeoverShutdown() -> localStore_.reset() -> RocksDbLocalStore::~RocksDbLocalStore(). 7. Thread C: RocksDbLocalStore::~RocksDbLocalStore() signals the thread pool to exit and waits for the pool's threads to exit. Because thread C is one of the threads managed by RocksDbLocalStore's thread pool, the signal is never handled and RocksDbLocalStore::~RocksDbLocalStore() never finishes. Fix this deadlock by executing EdenServer::shutdown()'s callback (in EdenServer::performTakeoverShutdown()) on a different thread. Reviewed By: simpkins Differential Revision: D14337058 fbshipit-source-id: 1d63b4e7d8f5103a2dde31e329150bf763be3db7
62 lines
1.9 KiB
C++
62 lines
1.9 KiB
C++
/*
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* Copyright (c) 2016-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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*/
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#pragma once
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#include "eden/fs/rocksdb/RocksHandles.h"
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#include "eden/fs/store/LocalStore.h"
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#include "eden/fs/utils/UnboundedQueueExecutor.h"
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namespace facebook {
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namespace eden {
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class FaultInjector;
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class ReloadableConfig;
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/** An implementation of LocalStore that uses RocksDB for the underlying
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* storage.
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*/
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class RocksDbLocalStore : public LocalStore {
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public:
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/**
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* The given FaultInjector must be valid during the lifetime of this
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* RocksDbLocalStore object.
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*/
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explicit RocksDbLocalStore(
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AbsolutePathPiece pathToRocksDb,
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FaultInjector*,
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std::shared_ptr<ReloadableConfig> config = nullptr);
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~RocksDbLocalStore();
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void close() override;
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void clearKeySpace(KeySpace keySpace) override;
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void compactKeySpace(KeySpace keySpace) override;
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StoreResult get(LocalStore::KeySpace keySpace, folly::ByteRange key)
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const override;
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FOLLY_NODISCARD folly::Future<StoreResult> getFuture(
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KeySpace keySpace,
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folly::ByteRange key) const override;
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FOLLY_NODISCARD folly::Future<std::vector<StoreResult>> getBatch(
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KeySpace keySpace,
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const std::vector<folly::ByteRange>& keys) const override;
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bool hasKey(LocalStore::KeySpace keySpace, folly::ByteRange key)
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const override;
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void put(
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LocalStore::KeySpace keySpace,
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folly::ByteRange key,
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folly::ByteRange value) override;
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std::unique_ptr<WriteBatch> beginWrite(size_t bufSize = 0) override;
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private:
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FaultInjector& faultInjector_;
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RocksHandles dbHandles_;
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mutable UnboundedQueueExecutor ioPool_;
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};
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} // namespace eden
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} // namespace facebook
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