Store lz4 blocks as uncompressed if compression makes data larger
This will change cow size estimation. But since we haven't put lz4 on
SAC website yet, we can still change it.
Bug: 228478555
Test: th
Change-Id: Ifba7107954622ea04cbd25115700dfba50cec9c6
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_compress.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_compress.cpp
index e58f45a..0eb231b 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_compress.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_compress.cpp
@@ -84,7 +84,13 @@
<< ", compression bound: " << bound << ", ret: " << compressed_size;
return {};
}
- buffer.resize(compressed_size);
+ // Don't run compression if the compressed output is larger
+ if (compressed_size >= length) {
+ buffer.resize(length);
+ memcpy(buffer.data(), data, length);
+ } else {
+ buffer.resize(compressed_size);
+ }
return buffer;
}
default:
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.cpp
index a4d2277..139a29f 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.cpp
@@ -273,6 +273,18 @@
<< actual_buffer_size << " bytes";
return false;
}
+ // If input size is same as output size, then input is uncompressed.
+ if (stream_->Size() == output_size) {
+ size_t bytes_read = 0;
+ stream_->Read(output_buffer, output_size, &bytes_read);
+ if (bytes_read != output_size) {
+ LOG(ERROR) << "Failed to read all input at once. Expected: " << output_size
+ << " actual: " << bytes_read;
+ return false;
+ }
+ sink_->ReturnData(output_buffer, output_size);
+ return true;
+ }
std::string input_buffer;
input_buffer.resize(stream_->Size());
size_t bytes_read = 0;