Shove type into source_info

We can shove type into source info to save 8 bits in per cow operation.
We only need 4 bits inside of source_info to enumerate all the types of
Cow Operation:

static constexpr uint8_t kCowCopyOp = 1;
static constexpr uint8_t kCowReplaceOp = 2;
static constexpr uint8_t kCowZeroOp = 3;
static constexpr uint8_t kCowLabelOp = 4;
static constexpr uint8_t kCowClusterOp = 5;
static constexpr uint8_t kCowXorOp = 6;
static constexpr uint8_t kCowSequenceOp = 7;
static constexpr uint8_t kCowFooterOp = -1;

Test: critical ota paths on pixel
Change-Id: I22049db0b39a55bd8f863339f3751d3146d5c1e9
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
index 2beeb9f..bfa8f6b 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
@@ -149,9 +149,6 @@
 
 // The on disk format of cow (currently ==  CowOperation)
 struct CowOperationV3 {
-    // The operation code (see the constants and structures below).
-    uint8_t type;
-
     // If this operation reads from the data section of the COW, this contains
     // the length.
     uint16_t data_length;
@@ -159,6 +156,10 @@
     // The block of data in the new image that this operation modifies.
     uint32_t new_block;
 
+    // source_info with have the following layout
+    // |---4 bits ---| ---12 bits---| --- 48 bits ---|
+    // |--- type --- | -- unused -- | --- source --- |
+    //
     // The value of |source| depends on the operation code.
     //
     // CopyOp: a 32-bit block location in the source image.
@@ -167,8 +168,6 @@
     // ZeroOp: unused
     // LabelOp: a 64-bit opaque identifier.
     //
-    // For ops other than Label:
-    //  Bits 47-62 are reserved and must be zero.
     // A block is compressed if it’s data is < block_sz
     uint64_t source_info;
 } __attribute__((packed));
@@ -200,9 +199,21 @@
 static constexpr uint8_t kCowReadAheadInProgress = 1;
 static constexpr uint8_t kCowReadAheadDone = 2;
 
-static constexpr uint64_t kCowOpSourceInfoDataMask = (1ULL << 48) - 1;
+// this is a mask to grab the last 48 bits of a 64 bit integer
+static constexpr uint64_t kCowOpSourceInfoDataMask = (0x1ULL << 48) - 1;
+// this is a mask to grab the first 4 bits of a 64 bit integer
+static constexpr uint64_t kCowOpSourceInfoTypeBit = 60;
+static constexpr uint64_t kCowOpSourceInfoTypeNumBits = 4;
+static constexpr uint64_t kCowOpSourceInfoTypeMask = (1 << kCowOpSourceInfoTypeNumBits) - 1;
 
-static inline uint64_t GetCowOpSourceInfoData(const CowOperation& op) {
+static constexpr void SetCowOpSourceInfoType(CowOperation* op, const uint8_t type) {
+    op->source_info |= uint64_t(type) << kCowOpSourceInfoTypeBit;
+}
+static constexpr uint64_t GetCowOpSourceInfoType(const CowOperation& op) {
+    return (op.source_info >> kCowOpSourceInfoTypeBit) & kCowOpSourceInfoTypeMask;
+}
+
+static constexpr uint64_t GetCowOpSourceInfoData(const CowOperation& op) {
     return op.source_info & kCowOpSourceInfoDataMask;
 }
 
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_format.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_format.cpp
index 5ab4f7a..1be592d 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_format.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_format.cpp
@@ -81,16 +81,19 @@
 
 std::ostream& operator<<(std::ostream& os, CowOperation const& op) {
     os << "CowOperation(";
-    EmitCowTypeString(os, op.type);
-    if (op.type == kCowReplaceOp || op.type == kCowXorOp || op.type == kCowSequenceOp) {
+    EmitCowTypeString(os, GetCowOpSourceInfoType(op));
+    if (GetCowOpSourceInfoType(op) == kCowReplaceOp || GetCowOpSourceInfoType(op) == kCowXorOp ||
+        GetCowOpSourceInfoType(op) == kCowSequenceOp) {
         os << ", data_length:" << op.data_length;
     }
-    if (op.type != kCowClusterOp && op.type != kCowSequenceOp && op.type != kCowLabelOp) {
+    if (GetCowOpSourceInfoType(op) != kCowClusterOp &&
+        GetCowOpSourceInfoType(op) != kCowSequenceOp && GetCowOpSourceInfoType(op) != kCowLabelOp) {
         os << ", new_block:" << op.new_block;
     }
-    if (op.type == kCowXorOp || op.type == kCowReplaceOp || op.type == kCowCopyOp) {
+    if (GetCowOpSourceInfoType(op) == kCowXorOp || GetCowOpSourceInfoType(op) == kCowReplaceOp ||
+        GetCowOpSourceInfoType(op) == kCowCopyOp) {
         os << ", source:" << (op.source_info & kCowOpSourceInfoDataMask);
-    } else if (op.type == kCowClusterOp) {
+    } else if (GetCowOpSourceInfoType(op) == kCowClusterOp) {
         os << ", cluster_data:" << (op.source_info & kCowOpSourceInfoDataMask);
     } else {
         os << ", label:0x" << android::base::StringPrintf("%" PRIx64, op.source_info);
@@ -120,7 +123,7 @@
 }
 
 bool IsMetadataOp(const CowOperation& op) {
-    switch (op.type) {
+    switch (GetCowOpSourceInfoType(op)) {
         case kCowLabelOp:
         case kCowClusterOp:
         case kCowFooterOp:
@@ -132,7 +135,7 @@
 }
 
 bool IsOrderedOp(const CowOperation& op) {
-    switch (op.type) {
+    switch (GetCowOpSourceInfoType(op)) {
         case kCowCopyOp:
         case kCowXorOp:
             return true;
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
index 85fd4c3..c52705c 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
@@ -24,6 +24,7 @@
 
 #include <android-base/file.h>
 #include <android-base/logging.h>
+#include <libsnapshot/cow_format.h>
 #include <libsnapshot/cow_reader.h>
 #include <zlib.h>
 
@@ -110,7 +111,7 @@
         const auto& v2_op = parser.ops()->at(i);
 
         auto& new_op = ops_->at(i);
-        new_op.type = v2_op.type;
+        SetCowOpSourceInfoType(&new_op, v2_op.type);
         new_op.data_length = v2_op.data_length;
 
         if (v2_op.new_block > std::numeric_limits<uint32_t>::max()) {
@@ -120,7 +121,7 @@
         new_op.new_block = v2_op.new_block;
 
         uint64_t source_info = v2_op.source;
-        if (new_op.type != kCowLabelOp) {
+        if (GetCowOpSourceInfoType(new_op) != kCowLabelOp) {
             source_info &= kCowOpSourceInfoDataMask;
             if (source_info != v2_op.source) {
                 LOG(ERROR) << "Out-of-range source value in COW op: " << v2_op;
@@ -137,7 +138,7 @@
                 return false;
             }
         }
-        new_op.source_info = source_info;
+        new_op.source_info |= source_info;
     }
 
     // If we're resuming a write, we're not ready to merge
@@ -260,7 +261,7 @@
     for (size_t i = 0; i < ops_->size(); i++) {
         auto& current_op = ops_->data()[i];
 
-        if (current_op.type == kCowSequenceOp) {
+        if (GetCowOpSourceInfoType(current_op) == kCowSequenceOp) {
             size_t seq_len = current_op.data_length / sizeof(uint32_t);
 
             merge_op_blocks->resize(merge_op_blocks->size() + seq_len);
@@ -572,7 +573,7 @@
 }
 
 bool CowReader::GetRawBytes(const CowOperation* op, void* buffer, size_t len, size_t* read) {
-    switch (op->type) {
+    switch (GetCowOpSourceInfoType(*op)) {
         case kCowSequenceOp:
         case kCowReplaceOp:
         case kCowXorOp:
@@ -665,7 +666,7 @@
     }
 
     uint64_t offset;
-    if (op->type == kCowXorOp) {
+    if (GetCowOpSourceInfoType(*op) == kCowXorOp) {
         offset = data_loc_->at(op->new_block);
     } else {
         offset = GetCowOpSourceInfoData(*op);
@@ -682,7 +683,7 @@
 }
 
 bool CowReader::GetSourceOffset(const CowOperation* op, uint64_t* source_offset) {
-    switch (op->type) {
+    switch (GetCowOpSourceInfoType(*op)) {
         case kCowCopyOp:
             *source_offset = GetCowOpSourceInfoData(*op) * header_.block_size;
             return true;
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp
index 83b5a12..aaaf20c 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp
@@ -26,6 +26,7 @@
 #include <android-base/logging.h>
 #include <android-base/unique_fd.h>
 #include <gflags/gflags.h>
+#include <libsnapshot/cow_format.h>
 #include <libsnapshot/cow_reader.h>
 #include "parser_v2.h"
 
@@ -198,7 +199,7 @@
 
         if (!FLAGS_silent && FLAGS_show_ops) std::cout << *op << "\n";
 
-        if ((FLAGS_decompress || extract_to >= 0) && op->type == kCowReplaceOp) {
+        if ((FLAGS_decompress || extract_to >= 0) && GetCowOpSourceInfoType(*op) == kCowReplaceOp) {
             if (reader.ReadData(op, buffer.data(), buffer.size()) < 0) {
                 std::cerr << "Failed to decompress for :" << *op << "\n";
                 success = false;
@@ -212,12 +213,13 @@
                     return false;
                 }
             }
-        } else if (extract_to >= 0 && !IsMetadataOp(*op) && op->type != kCowZeroOp) {
+        } else if (extract_to >= 0 && !IsMetadataOp(*op) &&
+                   GetCowOpSourceInfoType(*op) != kCowZeroOp) {
             PLOG(ERROR) << "Cannot extract op yet: " << *op;
             return false;
         }
 
-        if (op->type == kCowSequenceOp && FLAGS_show_merge_sequence) {
+        if (GetCowOpSourceInfoType(*op) == kCowSequenceOp && FLAGS_show_merge_sequence) {
             size_t read;
             std::vector<uint32_t> merge_op_blocks;
             size_t seq_len = op->data_length / sizeof(uint32_t);
@@ -235,13 +237,13 @@
             }
         }
 
-        if (op->type == kCowCopyOp) {
+        if (GetCowOpSourceInfoType(*op) == kCowCopyOp) {
             copy_ops++;
-        } else if (op->type == kCowReplaceOp) {
+        } else if (GetCowOpSourceInfoType(*op) == kCowReplaceOp) {
             replace_ops++;
-        } else if (op->type == kCowZeroOp) {
+        } else if (GetCowOpSourceInfoType(*op) == kCowZeroOp) {
             zero_ops++;
-        } else if (op->type == kCowXorOp) {
+        } else if (GetCowOpSourceInfoType(*op) == kCowXorOp) {
             xor_ops++;
         }
 
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/snapshot_reader.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/snapshot_reader.cpp
index a3e40d9..d7ee432 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/snapshot_reader.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/snapshot_reader.cpp
@@ -147,7 +147,7 @@
         op = ops_[chunk];
     }
 
-    if (!op || op->type == kCowCopyOp) {
+    if (!op || GetCowOpSourceInfoType(*op) == kCowCopyOp) {
         borrowed_fd fd = GetSourceFd();
         if (fd < 0) {
             // GetSourceFd sets errno.
@@ -169,15 +169,15 @@
             // ReadFullyAtOffset sets errno.
             return -1;
         }
-    } else if (op->type == kCowZeroOp) {
+    } else if (GetCowOpSourceInfoType(*op) == kCowZeroOp) {
         memset(buffer, 0, bytes_to_read);
-    } else if (op->type == kCowReplaceOp) {
+    } else if (GetCowOpSourceInfoType(*op) == kCowReplaceOp) {
         if (cow_->ReadData(op, buffer, bytes_to_read, start_offset) < bytes_to_read) {
             LOG(ERROR) << "CompressedSnapshotReader failed to read replace op";
             errno = EIO;
             return -1;
         }
-    } else if (op->type == kCowXorOp) {
+    } else if (GetCowOpSourceInfoType(*op) == kCowXorOp) {
         borrowed_fd fd = GetSourceFd();
         if (fd < 0) {
             // GetSourceFd sets errno.
@@ -208,7 +208,8 @@
             ((char*)buffer)[i] ^= data[i];
         }
     } else {
-        LOG(ERROR) << "CompressedSnapshotReader unknown op type: " << uint32_t(op->type);
+        LOG(ERROR) << "CompressedSnapshotReader unknown op type: "
+                   << uint32_t(GetCowOpSourceInfoType(*op));
         errno = EINVAL;
         return -1;
     }
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/test_v2.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/test_v2.cpp
index 35d74ba..d962875 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/test_v2.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/test_v2.cpp
@@ -25,6 +25,7 @@
 #include <libsnapshot/cow_reader.h>
 #include <libsnapshot/cow_writer.h>
 #include "cow_decompress.h"
+#include "libsnapshot/cow_format.h"
 #include "writer_v2.h"
 
 using android::base::unique_fd;
@@ -85,7 +86,7 @@
     size_t i = 0;
     while (!iter->AtEnd()) {
         auto op = iter->Get();
-        ASSERT_EQ(op->type, kCowCopyOp);
+        ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowCopyOp);
         ASSERT_EQ(op->data_length, 0);
         ASSERT_EQ(op->new_block, 10 + i);
         ASSERT_EQ(GetCowOpSourceInfoData(*op), 1000 + i);
@@ -131,7 +132,7 @@
     ASSERT_FALSE(iter->AtEnd());
     auto op = iter->Get();
 
-    ASSERT_EQ(op->type, kCowCopyOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowCopyOp);
     ASSERT_EQ(op->data_length, 0);
     ASSERT_EQ(op->new_block, 10);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 20);
@@ -142,7 +143,7 @@
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
 
-    ASSERT_EQ(op->type, kCowReplaceOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowReplaceOp);
     ASSERT_EQ(op->data_length, 4096);
     ASSERT_EQ(op->new_block, 50);
     ASSERT_TRUE(ReadData(reader, op, sink.data(), sink.size()));
@@ -153,7 +154,7 @@
     op = iter->Get();
 
     // Note: the zero operation gets split into two blocks.
-    ASSERT_EQ(op->type, kCowZeroOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowZeroOp);
     ASSERT_EQ(op->data_length, 0);
     ASSERT_EQ(op->new_block, 51);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 0);
@@ -162,7 +163,7 @@
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
 
-    ASSERT_EQ(op->type, kCowZeroOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowZeroOp);
     ASSERT_EQ(op->data_length, 0);
     ASSERT_EQ(op->new_block, 52);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 0);
@@ -206,7 +207,7 @@
     ASSERT_FALSE(iter->AtEnd());
     auto op = iter->Get();
 
-    ASSERT_EQ(op->type, kCowCopyOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowCopyOp);
     ASSERT_EQ(op->data_length, 0);
     ASSERT_EQ(op->new_block, 10);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 20);
@@ -217,7 +218,7 @@
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
 
-    ASSERT_EQ(op->type, kCowXorOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowXorOp);
     ASSERT_EQ(op->data_length, 4096);
     ASSERT_EQ(op->new_block, 50);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 98314);  // 4096 * 24 + 10
@@ -229,7 +230,7 @@
     op = iter->Get();
 
     // Note: the zero operation gets split into two blocks.
-    ASSERT_EQ(op->type, kCowZeroOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowZeroOp);
     ASSERT_EQ(op->data_length, 0);
     ASSERT_EQ(op->new_block, 51);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 0);
@@ -238,7 +239,7 @@
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
 
-    ASSERT_EQ(op->type, kCowZeroOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowZeroOp);
     ASSERT_EQ(op->data_length, 0);
     ASSERT_EQ(op->new_block, 52);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 0);
@@ -273,7 +274,7 @@
 
     std::string sink(data.size(), '\0');
 
-    ASSERT_EQ(op->type, kCowReplaceOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowReplaceOp);
     ASSERT_EQ(op->data_length, 56);  // compressed!
     ASSERT_EQ(op->new_block, 50);
     ASSERT_TRUE(ReadData(reader, op, sink.data(), sink.size()));
@@ -325,7 +326,7 @@
     while (!iter->AtEnd()) {
         auto op = iter->Get();
 
-        if (op->type == kCowXorOp) {
+        if (GetCowOpSourceInfoType(*op) == kCowXorOp) {
             total_blocks += 1;
             std::string sink(xor_data.size(), '\0');
             ASSERT_EQ(op->new_block, 50);
@@ -334,7 +335,7 @@
             ASSERT_EQ(sink, xor_data);
         }
 
-        if (op->type == kCowReplaceOp) {
+        if (GetCowOpSourceInfoType(*op) == kCowReplaceOp) {
             total_blocks += 1;
             if (op->new_block == 100) {
                 data.resize(options.block_size);
@@ -399,7 +400,7 @@
     while (!iter->AtEnd()) {
         auto op = iter->Get();
 
-        if (op->type == kCowReplaceOp) {
+        if (GetCowOpSourceInfoType(*op) == kCowReplaceOp) {
             total_blocks += 1;
             if (op->new_block == 50) {
                 data.resize(options.block_size);
@@ -519,7 +520,7 @@
 
     std::string sink(data.size(), '\0');
 
-    ASSERT_EQ(op->type, kCowReplaceOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowReplaceOp);
     ASSERT_EQ(op->data_length, 56);  // compressed!
     ASSERT_EQ(op->new_block, 50);
     ASSERT_TRUE(ReadData(reader, op, sink.data(), sink.size()));
@@ -529,7 +530,7 @@
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
 
-    ASSERT_EQ(op->type, kCowClusterOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowClusterOp);
 
     iter->Next();
     ASSERT_FALSE(iter->AtEnd());
@@ -546,7 +547,7 @@
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
 
-    ASSERT_EQ(op->type, kCowClusterOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowClusterOp);
 
     iter->Next();
     ASSERT_TRUE(iter->AtEnd());
@@ -580,7 +581,7 @@
     std::string sink(options.block_size, '\0');
 
     auto op = iter->Get();
-    ASSERT_EQ(op->type, kCowReplaceOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowReplaceOp);
     ASSERT_EQ(op->new_block, 51);
     ASSERT_TRUE(ReadData(reader, op, sink.data(), sink.size()));
 }
@@ -653,7 +654,7 @@
 
     ASSERT_FALSE(iter->AtEnd());
     auto op = iter->Get();
-    ASSERT_EQ(op->type, kCowReplaceOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowReplaceOp);
     ASSERT_TRUE(ReadData(reader, op, sink.data(), sink.size()));
     ASSERT_EQ(sink, data);
 
@@ -663,14 +664,14 @@
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowLabelOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowLabelOp);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 3);
 
     iter->Next();
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowReplaceOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowReplaceOp);
     ASSERT_TRUE(ReadData(reader, op, sink.data(), sink.size()));
     ASSERT_EQ(sink, data2);
 
@@ -716,14 +717,14 @@
 
     ASSERT_FALSE(iter->AtEnd());
     auto op = iter->Get();
-    ASSERT_EQ(op->type, kCowLabelOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowLabelOp);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 0);
 
     iter->Next();
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowZeroOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowZeroOp);
 
     iter->Next();
 
@@ -774,7 +775,7 @@
 
     ASSERT_FALSE(iter->AtEnd());
     auto op = iter->Get();
-    ASSERT_EQ(op->type, kCowLabelOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowLabelOp);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 5);
 
     iter->Next();
@@ -825,7 +826,7 @@
 
     ASSERT_FALSE(iter->AtEnd());
     auto op = iter->Get();
-    ASSERT_EQ(op->type, kCowReplaceOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowReplaceOp);
     ASSERT_TRUE(ReadData(reader, op, sink.data(), sink.size()));
     ASSERT_EQ(sink, data.substr(0, options.block_size));
 
@@ -835,7 +836,7 @@
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowReplaceOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowReplaceOp);
     ASSERT_TRUE(ReadData(reader, op, sink.data(), sink.size()));
     ASSERT_EQ(sink, data.substr(options.block_size, 2 * options.block_size));
 
@@ -843,25 +844,25 @@
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowLabelOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowLabelOp);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 4);
 
     iter->Next();
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowZeroOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowZeroOp);
 
     iter->Next();
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowZeroOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowZeroOp);
 
     iter->Next();
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowLabelOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowLabelOp);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 5);
 
     iter->Next();
@@ -906,7 +907,7 @@
 
     ASSERT_FALSE(iter->AtEnd());
     auto op = iter->Get();
-    ASSERT_EQ(op->type, kCowReplaceOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowReplaceOp);
     ASSERT_TRUE(ReadData(reader, op, sink.data(), sink.size()));
     ASSERT_EQ(sink, data.substr(0, options.block_size));
 
@@ -914,51 +915,51 @@
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowLabelOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowLabelOp);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 4);
 
     iter->Next();
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowZeroOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowZeroOp);
 
     iter->Next();
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowClusterOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowClusterOp);
 
     iter->Next();
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowZeroOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowZeroOp);
 
     iter->Next();
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowLabelOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowLabelOp);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 5);
 
     iter->Next();
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowCopyOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowCopyOp);
 
     iter->Next();
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowClusterOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowClusterOp);
 
     iter->Next();
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowLabelOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowLabelOp);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 6);
 
     iter->Next();
@@ -1005,14 +1006,14 @@
 
     ASSERT_FALSE(iter->AtEnd());
     auto op = iter->Get();
-    ASSERT_EQ(op->type, kCowLabelOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowLabelOp);
     ASSERT_EQ(GetCowOpSourceInfoData(*op), 50);
 
     iter->Next();
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowReplaceOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowReplaceOp);
     ASSERT_TRUE(ReadData(reader, op, sink.data(), sink.size()));
     ASSERT_EQ(sink, data2);
 
@@ -1020,7 +1021,7 @@
 
     ASSERT_FALSE(iter->AtEnd());
     op = iter->Get();
-    ASSERT_EQ(op->type, kCowClusterOp);
+    ASSERT_EQ(GetCowOpSourceInfoType(*op), kCowClusterOp);
 
     iter->Next();
 
@@ -1117,12 +1118,12 @@
         num_in_cluster++;
         max_in_cluster = std::max(max_in_cluster, num_in_cluster);
 
-        if (op->type == kCowReplaceOp) {
+        if (GetCowOpSourceInfoType(*op) == kCowReplaceOp) {
             num_replace++;
 
             ASSERT_EQ(op->new_block, num_replace);
             ASSERT_TRUE(CompareDataBlock(&reader, op, "Block " + std::to_string(num_replace)));
-        } else if (op->type == kCowClusterOp) {
+        } else if (GetCowOpSourceInfoType(*op) == kCowClusterOp) {
             num_in_cluster = 0;
             num_clusters++;
         }
@@ -1178,12 +1179,12 @@
         num_in_cluster++;
         max_in_cluster = std::max(max_in_cluster, num_in_cluster);
 
-        if (op->type == kCowReplaceOp) {
+        if (GetCowOpSourceInfoType(*op) == kCowReplaceOp) {
             num_replace++;
 
             ASSERT_EQ(op->new_block, num_replace);
             ASSERT_TRUE(CompareDataBlock(&reader, op, "Block " + std::to_string(num_replace)));
-        } else if (op->type == kCowClusterOp) {
+        } else if (GetCowOpSourceInfoType(*op) == kCowClusterOp) {
             num_in_cluster = 0;
             num_clusters++;
         }
@@ -1229,12 +1230,12 @@
 
         num_in_cluster++;
         max_in_cluster = std::max(max_in_cluster, num_in_cluster);
-        if (op->type == kCowReplaceOp) {
+        if (GetCowOpSourceInfoType(*op) == kCowReplaceOp) {
             num_replace++;
 
             ASSERT_EQ(op->new_block, num_replace);
             ASSERT_TRUE(CompareDataBlock(&reader, op, "Block " + std::to_string(num_replace)));
-        } else if (op->type == kCowClusterOp) {
+        } else if (GetCowOpSourceInfoType(*op) == kCowClusterOp) {
             num_in_cluster = 0;
             num_clusters++;
         }
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp
index 2373d4d..a4d617f 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp
@@ -49,5 +49,14 @@
     std::unique_ptr<TemporaryFile> cow_;
 };
 
+TEST_F(CowOperationV3Test, CowTypeTest) {
+    CowOperationV3 new_op;
+    CowOperationV2 old_op;
+    old_op.type = kCowReplaceOp;
+    ASSERT_NE(GetCowOpSourceInfoType(new_op), old_op.type);
+    SetCowOpSourceInfoType(&new_op, old_op.type);
+    ASSERT_EQ(GetCowOpSourceInfoType(new_op), old_op.type);
+}
+
 }  // namespace snapshot
 }  // namespace android
\ No newline at end of file
diff --git a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd.cpp b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd.cpp
index 6dc082e..0be6ff5 100644
--- a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd.cpp
@@ -25,6 +25,7 @@
 #include <csignal>
 #include <optional>
 #include <set>
+#include "libsnapshot/cow_format.h"
 
 #include <android-base/file.h>
 #include <android-base/logging.h>
@@ -406,9 +407,9 @@
             break;
         }
 
-        if (cow_op->type == kCowReplaceOp) {
+        if (GetCowOpSourceInfoType(*cow_op) == kCowReplaceOp) {
             replace_ops++;
-        } else if (cow_op->type == kCowZeroOp) {
+        } else if (GetCowOpSourceInfoType(*cow_op) == kCowZeroOp) {
             zero_ops++;
         }
 
@@ -540,7 +541,7 @@
             chunk_vec_.push_back(std::make_pair(ChunkToSector(data_chunk_id), cow_op));
             offset += sizeof(struct disk_exception);
             num_ops += 1;
-            if (cow_op->type == kCowCopyOp) {
+            if (GetCowOpSourceInfoType(*cow_op) == kCowCopyOp) {
                 copy_ops++;
             }
 
diff --git a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_readahead.cpp b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_readahead.cpp
index ab0b309..b2a4f2c 100644
--- a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_readahead.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_readahead.cpp
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include "libsnapshot/cow_format.h"
 #include "snapuserd.h"
 
 #include <csignal>
@@ -192,7 +193,7 @@
         const CowOperation* cow_op = GetRAOpIter();
         CHECK_NE(cow_op, nullptr);
         *source_offset = GetCowOpSourceInfoData(*cow_op);
-        if (cow_op->type == kCowCopyOp) {
+        if (GetCowOpSourceInfoData(*cow_op) == kCowCopyOp) {
             *source_offset *= BLOCK_SZ;
         }
         RAIterNext();
@@ -211,7 +212,7 @@
             const CowOperation* op = GetRAOpIter();
             CHECK_NE(op, nullptr);
             uint64_t next_offset = GetCowOpSourceInfoData(*op);
-            if (op->type == kCowCopyOp) {
+            if (GetCowOpSourceInfoData(*op) == kCowCopyOp) {
                 next_offset *= BLOCK_SZ;
             }
             if (next_offset + nr_consecutive * BLOCK_SZ != *source_offset) {
diff --git a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp
index 571b352..0930a5d 100644
--- a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include "libsnapshot/cow_format.h"
 #include "snapuserd.h"
 
 #include <csignal>
@@ -177,7 +178,7 @@
         return false;
     }
 
-    switch (cow_op->type) {
+    switch (GetCowOpSourceInfoType(*cow_op)) {
         case kCowReplaceOp: {
             return ProcessReplaceOp(cow_op);
         }
@@ -191,7 +192,8 @@
         }
 
         default: {
-            SNAP_LOG(ERROR) << "Unsupported operation-type found: " << cow_op->type;
+            SNAP_LOG(ERROR) << "Unsupported operation-type found: "
+                            << GetCowOpSourceInfoType(*cow_op);
         }
     }
     return false;
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/merge_worker.cpp b/fs_mgr/libsnapshot/snapuserd/user-space-merge/merge_worker.cpp
index 11b8d7c..d06ba58 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/merge_worker.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/merge_worker.cpp
@@ -17,6 +17,7 @@
 
 #include <pthread.h>
 
+#include "libsnapshot/cow_format.h"
 #include "snapuserd_core.h"
 #include "utility.h"
 
@@ -114,13 +115,13 @@
                 SNAP_LOG(ERROR) << "AcquireBuffer failed in MergeReplaceOps";
                 return false;
             }
-            if (cow_op->type == kCowReplaceOp) {
+            if (GetCowOpSourceInfoType(*cow_op) == kCowReplaceOp) {
                 if (!reader_->ReadData(cow_op, buffer, BLOCK_SZ)) {
                     SNAP_LOG(ERROR) << "Failed to read COW in merge";
                     return false;
                 }
             } else {
-                CHECK(cow_op->type == kCowZeroOp);
+                CHECK(GetCowOpSourceInfoType(*cow_op) == kCowZeroOp);
                 memset(buffer, 0, BLOCK_SZ);
             }
         }
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/read_worker.cpp b/fs_mgr/libsnapshot/snapuserd/user-space-merge/read_worker.cpp
index 5cb13e8..ffa23ea 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/read_worker.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/read_worker.cpp
@@ -18,6 +18,7 @@
 
 #include <pthread.h>
 
+#include "libsnapshot/cow_format.h"
 #include "snapuserd_core.h"
 #include "utility.h"
 
@@ -63,7 +64,7 @@
                     << " Op: " << *cow_op;
     if (!android::base::ReadFullyAtOffset(backing_store_fd_, buffer, BLOCK_SZ, offset)) {
         std::string op;
-        if (cow_op->type == kCowCopyOp)
+        if (GetCowOpSourceInfoType(*cow_op) == kCowCopyOp)
             op = "Copy-op";
         else {
             op = "Xor-op";
@@ -133,7 +134,7 @@
         }
         case MERGE_GROUP_STATE::GROUP_MERGE_PENDING: {
             bool ret;
-            if (cow_op->type == kCowCopyOp) {
+            if (GetCowOpSourceInfoType(*cow_op) == kCowCopyOp) {
                 ret = ProcessCopyOp(cow_op, buffer);
             } else {
                 ret = ProcessXorOp(cow_op, buffer);
@@ -167,7 +168,7 @@
         return false;
     }
 
-    switch (cow_op->type) {
+    switch (GetCowOpSourceInfoType(*cow_op)) {
         case kCowReplaceOp: {
             return ProcessReplaceOp(cow_op, buffer);
         }
@@ -183,7 +184,7 @@
         }
 
         default: {
-            SNAP_LOG(ERROR) << "Unknown operation-type found: " << cow_op->type;
+            SNAP_LOG(ERROR) << "Unknown operation-type found: " << GetCowOpSourceInfoType(*cow_op);
         }
     }
     return false;
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.cpp b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.cpp
index e886ec3..536ff2f 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_core.cpp
@@ -24,6 +24,7 @@
 #include <android-base/strings.h>
 #include <snapuserd/dm_user_block_server.h>
 
+#include "libsnapshot/cow_format.h"
 #include "merge_worker.h"
 #include "read_worker.h"
 
@@ -196,13 +197,13 @@
     while (!cowop_iter->AtEnd()) {
         const CowOperation* cow_op = cowop_iter->Get();
 
-        if (cow_op->type == kCowCopyOp) {
+        if (GetCowOpSourceInfoType(*cow_op) == kCowCopyOp) {
             copy_ops += 1;
-        } else if (cow_op->type == kCowReplaceOp) {
+        } else if (GetCowOpSourceInfoType(*cow_op) == kCowReplaceOp) {
             replace_ops += 1;
-        } else if (cow_op->type == kCowZeroOp) {
+        } else if (GetCowOpSourceInfoType(*cow_op) == kCowZeroOp) {
             zero_ops += 1;
-        } else if (cow_op->type == kCowXorOp) {
+        } else if (GetCowOpSourceInfoType(*cow_op) == kCowXorOp) {
             xor_ops += 1;
         }
 
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.cpp b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.cpp
index 998d233..d7d43a6 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_readahead.cpp
@@ -18,6 +18,7 @@
 
 #include <pthread.h>
 
+#include "libsnapshot/cow_format.h"
 #include "snapuserd_core.h"
 #include "utility.h"
 
@@ -77,7 +78,7 @@
         SNAP_LOG(ERROR) << "PrepareNextReadAhead operation has no source offset: " << *cow_op;
         return nr_consecutive;
     }
-    if (cow_op->type == kCowXorOp) {
+    if (GetCowOpSourceInfoType(*cow_op) == kCowXorOp) {
         xor_op_vec.push_back(cow_op);
     }
 
@@ -106,7 +107,7 @@
             break;
         }
 
-        if (op->type == kCowXorOp) {
+        if (GetCowOpSourceInfoType(*op) == kCowXorOp) {
             xor_op_vec.push_back(op);
         }