libsnapshot: Implement CowWriterV3:EmitBlocks
Add in replace ops to WriterV3 without compression support (will be
added in later). CowReader also has to be changed since we no longer
have a CowFooter (our checks need to be updated correspondingly).
We need next_data_pos_ to be pointed to after the operation buffer. This
section is appended to incrementally as we write replace + xor
operations
Test: cow_api_test
Change-Id: Ie979c72f842edd04337d900fd43dac8031207517
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
index c20194d..93c31bb 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
@@ -601,8 +601,8 @@
bool CowReader::GetRawBytes(uint64_t offset, void* buffer, size_t len, size_t* read) {
// Validate the offset, taking care to acknowledge possible overflow of offset+len.
- if (offset < header_.prefix.header_size || offset >= fd_size_ - sizeof(CowFooter) ||
- len >= fd_size_ || offset + len > fd_size_ - sizeof(CowFooter)) {
+ if (offset < header_.prefix.header_size || offset >= fd_size_ || offset + len > fd_size_ ||
+ len >= fd_size_) {
LOG(ERROR) << "invalid data offset: " << offset << ", " << len << " bytes";
return false;
}
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp
index 07c1d4f..214eb1c 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp
@@ -51,6 +51,11 @@
std::unique_ptr<TemporaryFile> cow_;
};
+// Helper to check read sizes.
+static inline bool ReadData(CowReader& reader, const CowOperation* op, void* buffer, size_t size) {
+ return reader.ReadData(op, buffer, size) == size;
+}
+
TEST_F(CowTestV3, CowHeaderV2Test) {
CowOptions options;
options.cluster_ops = 5;
@@ -120,5 +125,86 @@
ASSERT_EQ(op->source_info, 0);
}
+TEST_F(CowTestV3, ReplaceOp) {
+ CowOptions options;
+ options.op_count_max = 20;
+ options.scratch_space = false;
+ auto writer = CreateCowWriter(3, options, GetCowFd());
+ std::string data = "This is some data, believe it";
+ data.resize(options.block_size, '\0');
+
+ ASSERT_TRUE(writer->AddRawBlocks(5, data.data(), data.size()));
+ ASSERT_TRUE(writer->Finalize());
+
+ CowReader reader;
+ ASSERT_TRUE(reader.Parse(cow_->fd));
+
+ const auto& header = reader.header_v3();
+ ASSERT_EQ(header.prefix.magic, kCowMagicNumber);
+ ASSERT_EQ(header.prefix.major_version, 3);
+ ASSERT_EQ(header.prefix.minor_version, kCowVersionMinor);
+ ASSERT_EQ(header.block_size, options.block_size);
+ ASSERT_EQ(header.op_count, 1);
+
+ auto iter = reader.GetOpIter();
+ ASSERT_NE(iter, nullptr);
+ ASSERT_FALSE(iter->AtEnd());
+
+ auto op = iter->Get();
+ std::string sink(data.size(), '\0');
+
+ ASSERT_EQ(op->type, kCowReplaceOp);
+ ASSERT_EQ(op->data_length, 4096);
+ ASSERT_EQ(op->new_block, 5);
+ ASSERT_TRUE(ReadData(reader, op, sink.data(), sink.size()));
+ ASSERT_EQ(sink, data);
+}
+
+TEST_F(CowTestV3, ConsecutiveReplaceOp) {
+ CowOptions options;
+ options.op_count_max = 20;
+ options.scratch_space = false;
+ auto writer = CreateCowWriter(3, options, GetCowFd());
+ std::string data;
+ data.resize(options.block_size * 5);
+ for (int i = 0; i < data.size(); i++) {
+ data[i] = char(rand() % 256);
+ }
+
+ ASSERT_TRUE(writer->AddRawBlocks(5, data.data(), data.size()));
+ ASSERT_TRUE(writer->Finalize());
+
+ CowReader reader;
+ ASSERT_TRUE(reader.Parse(cow_->fd));
+
+ const auto& header = reader.header_v3();
+ ASSERT_EQ(header.prefix.magic, kCowMagicNumber);
+ ASSERT_EQ(header.prefix.major_version, 3);
+ ASSERT_EQ(header.prefix.minor_version, kCowVersionMinor);
+ ASSERT_EQ(header.block_size, options.block_size);
+ ASSERT_EQ(header.op_count, 5);
+
+ auto iter = reader.GetOpIter();
+ ASSERT_NE(iter, nullptr);
+ ASSERT_FALSE(iter->AtEnd());
+
+ size_t i = 0;
+ std::string sink(data.size(), '\0');
+
+ while (!iter->AtEnd()) {
+ auto op = iter->Get();
+ ASSERT_EQ(op->type, kCowReplaceOp);
+ ASSERT_EQ(op->data_length, options.block_size);
+ ASSERT_EQ(op->new_block, 5 + i);
+ ASSERT_TRUE(
+ ReadData(reader, op, sink.data() + (i * options.block_size), options.block_size));
+ iter->Next();
+ i++;
+ }
+ ASSERT_EQ(sink, data);
+
+ ASSERT_EQ(i, 5);
+}
+
} // namespace snapshot
} // namespace android
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.cpp
index ecbf97e..d7aee13 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.cpp
@@ -161,6 +161,9 @@
LOG(ERROR) << "Header sync failed";
return false;
}
+ next_data_pos_ =
+ sizeof(CowHeaderV3) + header_.buffer_size + header_.op_count_max * sizeof(CowOperation);
+
return true;
}
@@ -171,10 +174,7 @@
}
bool CowWriterV3::EmitRawBlocks(uint64_t new_block_start, const void* data, size_t size) {
- LOG(ERROR) << __LINE__ << " " << __FILE__ << " <- function here should never be called";
-
- if (new_block_start || data || size) return false;
- return false;
+ return EmitBlocks(new_block_start, data, size, 0, 0, kCowReplaceOp);
}
bool CowWriterV3::EmitXorBlocks(uint32_t new_block_start, const void* data, size_t size,
@@ -184,6 +184,33 @@
return false;
}
+bool CowWriterV3::EmitBlocks(uint64_t new_block_start, const void* data, size_t size,
+ uint64_t old_block, uint16_t offset, uint8_t type) {
+ const uint8_t* iter = reinterpret_cast<const uint8_t*>(data);
+
+ // Placing here until we support XOR ops
+ CHECK_EQ(old_block, 0);
+ CHECK_EQ(offset, 0);
+
+ const size_t num_blocks = (size / header_.block_size);
+
+ for (size_t i = 0; i < num_blocks; i++) {
+ CowOperation op = {};
+ op.new_block = new_block_start + i;
+
+ op.type = type;
+ op.source_info = next_data_pos_;
+ op.data_length = static_cast<uint16_t>(header_.block_size);
+ if (!WriteOperation(op, iter, header_.block_size)) {
+ LOG(ERROR) << "AddRawBlocks: write failed";
+ return false;
+ }
+ iter += header_.block_size;
+ }
+
+ return true;
+}
+
bool CowWriterV3::EmitZeroBlocks(uint64_t new_block_start, uint64_t num_blocks) {
for (uint64_t i = 0; i < num_blocks; i++) {
CowOperationV3 op;
@@ -210,7 +237,7 @@
return false;
}
-bool CowWriterV3::WriteOperation(const CowOperationV3& op) {
+bool CowWriterV3::WriteOperation(const CowOperationV3& op, const void* data, size_t size) {
if (IsEstimating()) {
header_.op_count++;
header_.op_count_max++;
@@ -224,10 +251,20 @@
const off_t offset = GetOpOffset(header_.op_count);
if (!android::base::WriteFullyAtOffset(fd_, &op, sizeof(op), offset)) {
+ PLOG(ERROR) << "write failed for " << op << " at " << offset;
return false;
}
-
+ if (data && size > 0) {
+ if (!android::base::WriteFullyAtOffset(fd_, data, size, next_data_pos_)) {
+ PLOG(ERROR) << "write failed for data of size: " << size
+ << " at offset: " << next_data_pos_;
+ return false;
+ }
+ }
header_.op_count++;
+ next_data_pos_ += op.data_length;
+ next_op_pos_ += sizeof(CowOperationV3);
+
return true;
}
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.h b/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.h
index 8717c01..af71a03 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.h
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.h
@@ -43,7 +43,9 @@
void SetupHeaders();
bool ParseOptions();
bool OpenForWrite();
- bool WriteOperation(const CowOperationV3& op);
+ bool WriteOperation(const CowOperationV3& op, const void* data = nullptr, size_t size = 0);
+ bool EmitBlocks(uint64_t new_block_start, const void* data, size_t size, uint64_t old_block,
+ uint16_t offset, uint8_t type);
off_t GetOpOffset(uint32_t op_index) const {
CHECK_LT(op_index, header_.op_count_max);
@@ -55,6 +57,9 @@
CowHeaderV3 header_{};
CowCompression compression_;
+ uint64_t next_op_pos_ = 0;
+ uint64_t next_data_pos_ = 0;
+
// in the case that we are using one thread for compression, we can store and re-use the same
// compressor
int num_compress_threads_ = 1;