142 lines
4.7 KiB
C++
142 lines
4.7 KiB
C++
// Copyright (C) 2020 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#pragma once
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#include <linux/types.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <csignal>
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#include <cstring>
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#include <iostream>
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#include <limits>
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#include <map>
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#include <string>
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#include <thread>
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#include <vector>
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#include <android-base/file.h>
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#include <android-base/logging.h>
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#include <android-base/stringprintf.h>
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#include <android-base/unique_fd.h>
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#include <libdm/dm.h>
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#include <libsnapshot/cow_reader.h>
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#include <libsnapshot/cow_writer.h>
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#include <libsnapshot/snapuserd_kernel.h>
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namespace android {
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namespace snapshot {
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using android::base::unique_fd;
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class BufferSink : public IByteSink {
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public:
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void Initialize(size_t size);
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void* GetBufPtr() { return buffer_.get(); }
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void Clear() { memset(GetBufPtr(), 0, buffer_size_); }
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void* GetPayloadBuffer(size_t size);
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void* GetBuffer(size_t requested, size_t* actual) override;
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void UpdateBufferOffset(size_t size) { buffer_offset_ += size; }
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struct dm_user_header* GetHeaderPtr();
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bool ReturnData(void*, size_t) override { return true; }
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void ResetBufferOffset() { buffer_offset_ = 0; }
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private:
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std::unique_ptr<uint8_t[]> buffer_;
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loff_t buffer_offset_;
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size_t buffer_size_;
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};
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class Snapuserd final {
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public:
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Snapuserd(const std::string& misc_name, const std::string& cow_device,
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const std::string& backing_device);
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bool InitBackingAndControlDevice();
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bool InitCowDevice();
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bool Run();
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const std::string& GetControlDevicePath() { return control_device_; }
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const std::string& GetMiscName() { return misc_name_; }
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uint64_t GetNumSectors() { return num_sectors_; }
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bool IsAttached() const { return ctrl_fd_ >= 0; }
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private:
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bool DmuserReadRequest();
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bool DmuserWriteRequest();
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bool ReadDmUserHeader();
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bool ReadDmUserPayload(void* buffer, size_t size);
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bool WriteDmUserPayload(size_t size);
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void ConstructKernelCowHeader();
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bool ReadMetadata();
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bool ZerofillDiskExceptions(size_t read_size);
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bool ReadDiskExceptions(chunk_t chunk, size_t size);
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int ReadUnalignedSector(sector_t sector, size_t size,
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std::map<sector_t, const CowOperation*>::iterator& it);
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int ReadData(sector_t sector, size_t size);
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bool IsChunkIdMetadata(chunk_t chunk);
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chunk_t GetNextAllocatableChunkId(chunk_t chunk_id);
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bool ProcessCowOp(const CowOperation* cow_op);
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bool ProcessReplaceOp(const CowOperation* cow_op);
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bool ProcessCopyOp(const CowOperation* cow_op);
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bool ProcessZeroOp();
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loff_t GetMergeStartOffset(void* merged_buffer, void* unmerged_buffer,
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int* unmerged_exceptions);
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int GetNumberOfMergedOps(void* merged_buffer, void* unmerged_buffer, loff_t offset,
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int unmerged_exceptions, bool* copy_op);
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bool ProcessMergeComplete(chunk_t chunk, void* buffer);
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sector_t ChunkToSector(chunk_t chunk) { return chunk << CHUNK_SHIFT; }
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chunk_t SectorToChunk(sector_t sector) { return sector >> CHUNK_SHIFT; }
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bool IsBlockAligned(int read_size) { return ((read_size & (BLOCK_SIZE - 1)) == 0); }
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std::string cow_device_;
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std::string backing_store_device_;
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std::string control_device_;
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std::string misc_name_;
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unique_fd cow_fd_;
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unique_fd backing_store_fd_;
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unique_fd ctrl_fd_;
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uint32_t exceptions_per_area_;
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uint64_t num_sectors_;
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std::unique_ptr<ICowOpIter> cowop_iter_;
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std::unique_ptr<ICowOpReverseIter> cowop_riter_;
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std::unique_ptr<CowReader> reader_;
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std::unique_ptr<CowWriter> writer_;
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// Vector of disk exception which is a
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// mapping of old-chunk to new-chunk
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std::vector<std::unique_ptr<uint8_t[]>> vec_;
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// Key - Sector
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// Value - cow operation
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//
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// chunk_map stores the pseudo mapping of sector
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// to COW operations. Each COW op is 4k; however,
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// we can get a read request which are as small
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// as 512 bytes. Hence, we need to binary search
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// in the chunk_map to find the nearest COW op.
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std::map<sector_t, const CowOperation*> chunk_map_;
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bool metadata_read_done_ = false;
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BufferSink bufsink_;
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};
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} // namespace snapshot
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} // namespace android
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