diff --git a/debuggerd/Android.bp b/debuggerd/Android.bp
index 31e284d..7d20995 100644
--- a/debuggerd/Android.bp
+++ b/debuggerd/Android.bp
@@ -32,9 +32,10 @@
     recovery_available: true,
     vendor_ramdisk_available: true,
     apex_available: [
+        "com.android.runtime",
         "com.android.virt",
         "//apex_available:platform",
-   ],
+    ],
 }
 
 cc_library_shared {
@@ -85,6 +86,7 @@
 
     export_header_lib_headers: ["libdebuggerd_common_headers"],
     export_include_dirs: ["tombstoned/include"],
+    apex_available: ["com.android.runtime"],
 }
 
 // Core implementation, linked into libdebuggerd_handler and the dynamic linker.
@@ -110,6 +112,9 @@
 
     export_header_lib_headers: ["libdebuggerd_common_headers"],
     export_include_dirs: ["include"],
+    apex_available: [
+        "com.android.runtime",
+    ],
 }
 
 // Implementation with a no-op fallback.
@@ -311,6 +316,9 @@
             header_libs: ["scudo_headers"],
         },
     },
+    apex_available: [
+        "com.android.runtime",
+    ],
 }
 
 cc_binary {
diff --git a/debuggerd/debuggerd_test.cpp b/debuggerd/debuggerd_test.cpp
index 8693fdd..c0522aa 100644
--- a/debuggerd/debuggerd_test.cpp
+++ b/debuggerd/debuggerd_test.cpp
@@ -2221,28 +2221,10 @@
   ASSERT_MATCH(result, match_str);
 }
 
-TEST(tombstoned, proto) {
-  const pid_t self = getpid();
-  unique_fd tombstoned_socket, text_fd, proto_fd;
-  ASSERT_TRUE(
-      tombstoned_connect(self, &tombstoned_socket, &text_fd, &proto_fd, kDebuggerdTombstoneProto));
-
-  tombstoned_notify_completion(tombstoned_socket.get());
-
-  ASSERT_NE(-1, text_fd.get());
-  ASSERT_NE(-1, proto_fd.get());
-
-  struct stat text_st;
-  ASSERT_EQ(0, fstat(text_fd.get(), &text_st));
-
-  // Give tombstoned some time to link the files into place.
-  std::this_thread::sleep_for(100ms * android::base::HwTimeoutMultiplier());
-
-  // Find the tombstone.
-  std::optional<std::string> tombstone_file;
+void CheckForTombstone(const struct stat& text_st, std::optional<std::string>& tombstone_file) {
+  static std::regex tombstone_re("tombstone_\\d+");
   std::unique_ptr<DIR, decltype(&closedir)> dir_h(opendir("/data/tombstones"), closedir);
   ASSERT_TRUE(dir_h != nullptr);
-  std::regex tombstone_re("tombstone_\\d+");
   dirent* entry;
   while ((entry = readdir(dir_h.get())) != nullptr) {
     if (!std::regex_match(entry->d_name, tombstone_re)) {
@@ -2260,8 +2242,38 @@
       break;
     }
   }
+}
 
-  ASSERT_TRUE(tombstone_file);
+TEST(tombstoned, proto) {
+  const pid_t self = getpid();
+  unique_fd tombstoned_socket, text_fd, proto_fd;
+  ASSERT_TRUE(
+      tombstoned_connect(self, &tombstoned_socket, &text_fd, &proto_fd, kDebuggerdTombstoneProto));
+
+  tombstoned_notify_completion(tombstoned_socket.get());
+
+  ASSERT_NE(-1, text_fd.get());
+  ASSERT_NE(-1, proto_fd.get());
+
+  struct stat text_st;
+  ASSERT_EQ(0, fstat(text_fd.get(), &text_st));
+
+  std::optional<std::string> tombstone_file;
+  // Allow up to 5 seconds for the tombstone to be written to the system.
+  const auto max_wait_time = std::chrono::seconds(5) * android::base::HwTimeoutMultiplier();
+  const auto start = std::chrono::high_resolution_clock::now();
+  while (true) {
+    std::this_thread::sleep_for(100ms);
+    CheckForTombstone(text_st, tombstone_file);
+    if (tombstone_file) {
+      break;
+    }
+    if (std::chrono::high_resolution_clock::now() - start > max_wait_time) {
+      break;
+    }
+  }
+
+  ASSERT_TRUE(tombstone_file) << "Timed out trying to find tombstone file.";
   std::string proto_path = tombstone_file.value() + ".pb";
 
   struct stat proto_fd_st;
diff --git a/fs_mgr/fs_mgr_remount.cpp b/fs_mgr/fs_mgr_remount.cpp
index 7ba4d2b..733ba2f 100644
--- a/fs_mgr/fs_mgr_remount.cpp
+++ b/fs_mgr/fs_mgr_remount.cpp
@@ -380,8 +380,8 @@
 
     // Now remount!
     for (const auto& mnt_point : {mount_point, entry.mount_point}) {
-        if (::mount(blk_device.c_str(), mnt_point.c_str(), entry.fs_type.c_str(), MS_REMOUNT,
-                    nullptr) == 0) {
+        if (::mount(blk_device.c_str(), mnt_point.c_str(), entry.fs_type.c_str(),
+                    MS_REMOUNT | MS_NOATIME, nullptr) == 0) {
             LOG(INFO) << "Remounted " << mnt_point << " as RW";
             return true;
         }
diff --git a/fs_mgr/libsnapshot/android/snapshot/snapshot.proto b/fs_mgr/libsnapshot/android/snapshot/snapshot.proto
index fa04c43..7e97dc0 100644
--- a/fs_mgr/libsnapshot/android/snapshot/snapshot.proto
+++ b/fs_mgr/libsnapshot/android/snapshot/snapshot.proto
@@ -114,6 +114,9 @@
 
     // Enable batching for COW writes
     bool batched_writes = 14;
+
+    // Size of v3 operation buffer. Needs to be determined during writer initialization
+    uint64 estimated_ops_buffer_size = 15;
 }
 
 // Next: 8
@@ -250,4 +253,7 @@
 
     // Whether this update attempt used io_uring.
     bool iouring_used = 13;
+
+    // Size of v3 operation buffer. Needs to be determined during writer initialization
+    uint64 estimated_op_count_max = 14;
 }
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
index 5b1e56c..7df976d 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
@@ -33,7 +33,10 @@
 
 namespace android {
 namespace snapshot {
-
+struct CowSizeInfo {
+    uint64_t cow_size;
+    uint64_t op_count_max;
+};
 struct CowOptions {
     uint32_t block_size = 4096;
     std::string compression;
@@ -56,7 +59,7 @@
     bool batch_write = false;
 
     // Size of the cow operation buffer; used in v3 only.
-    uint32_t op_count_max = 0;
+    uint64_t op_count_max = 0;
 };
 
 // Interface for writing to a snapuserd COW. All operations are ordered; merges
@@ -92,8 +95,9 @@
     // to ensure that the correct headers and footers are written.
     virtual bool Finalize() = 0;
 
-    // Return number of bytes the cow image occupies on disk.
-    virtual uint64_t GetCowSize() = 0;
+    // Return number of bytes the cow image occupies on disk + the size of sequence && ops buffer
+    // The latter two fields are used in v3 cow format and left as 0 for v2 cow format
+    virtual CowSizeInfo GetCowSizeInfo() const = 0;
 
     virtual uint32_t GetBlockSize() const = 0;
     virtual std::optional<uint32_t> GetMaxBlocks() const = 0;
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/mock_cow_writer.h b/fs_mgr/libsnapshot/include/libsnapshot/mock_cow_writer.h
index c58c654..8491fb0 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/mock_cow_writer.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/mock_cow_writer.h
@@ -24,8 +24,7 @@
     using FileDescriptor = chromeos_update_engine::FileDescriptor;
 
     MOCK_METHOD(bool, Finalize, (), (override));
-
-    MOCK_METHOD(uint64_t, GetCowSize, (), (override));
+    MOCK_METHOD(CowSizeInfo, GetCowSizeInfo, (), (const, override));
 
     MOCK_METHOD(bool, AddCopy, (uint64_t, uint64_t, uint64_t), (override));
     MOCK_METHOD(bool, AddRawBlocks, (uint64_t, const void*, size_t), (override));
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/test_v2.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/test_v2.cpp
index 49d86d8..1d1d24c 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/test_v2.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/test_v2.cpp
@@ -601,14 +601,14 @@
     ASSERT_TRUE(writer.AddCopy(10, 20));
     ASSERT_TRUE(writer.AddRawBlocks(50, data.data(), data.size()));
     ASSERT_TRUE(writer.AddZeroBlocks(51, 2));
-    auto size_before = writer.GetCowSize();
+    auto size_before = writer.GetCowSizeInfo().cow_size;
     ASSERT_TRUE(writer.Finalize());
-    auto size_after = writer.GetCowSize();
+    auto size_after = writer.GetCowSizeInfo().cow_size;
     ASSERT_EQ(size_before, size_after);
     struct stat buf;
 
     ASSERT_GE(fstat(cow_->fd, &buf), 0) << strerror(errno);
-    ASSERT_EQ(buf.st_size, writer.GetCowSize());
+    ASSERT_EQ(buf.st_size, writer.GetCowSizeInfo().cow_size);
 }
 
 TEST_F(CowTest, AppendLabelSmall) {
@@ -637,7 +637,7 @@
 
     struct stat buf;
     ASSERT_EQ(fstat(cow_->fd, &buf), 0);
-    ASSERT_EQ(buf.st_size, writer->GetCowSize());
+    ASSERT_EQ(buf.st_size, writer->GetCowSizeInfo().cow_size);
 
     // Read back both operations, and label.
     CowReader reader;
@@ -690,7 +690,7 @@
     ASSERT_TRUE(writer->AddRawBlocks(50, data.data(), data.size()));
     ASSERT_TRUE(writer->AddLabel(1));
     // Drop the tail end of the last op header, corrupting it.
-    ftruncate(cow_->fd, writer->GetCowSize() - sizeof(CowFooter) - 3);
+    ftruncate(cow_->fd, writer->GetCowSizeInfo().cow_size - sizeof(CowFooter) - 3);
 
     ASSERT_EQ(lseek(cow_->fd, 0, SEEK_SET), 0);
 
@@ -705,7 +705,7 @@
 
     struct stat buf;
     ASSERT_EQ(fstat(cow_->fd, &buf), 0);
-    ASSERT_EQ(buf.st_size, writer->GetCowSize());
+    ASSERT_EQ(buf.st_size, writer->GetCowSizeInfo().cow_size);
 
     // Read back both operations.
     CowReader reader;
@@ -763,7 +763,7 @@
 
     struct stat buf;
     ASSERT_EQ(fstat(cow_->fd, &buf), 0);
-    ASSERT_EQ(buf.st_size, writer->GetCowSize());
+    ASSERT_EQ(buf.st_size, writer->GetCowSizeInfo().cow_size);
 
     // Read back all valid operations
     CowReader reader;
@@ -812,7 +812,7 @@
 
     struct stat buf;
     ASSERT_EQ(fstat(cow_->fd, &buf), 0);
-    ASSERT_EQ(buf.st_size, writer->GetCowSize());
+    ASSERT_EQ(buf.st_size, writer->GetCowSizeInfo().cow_size);
 
     // Read back all ops
     CowReader reader;
@@ -989,7 +989,7 @@
 
     struct stat buf;
     ASSERT_EQ(fstat(cow_->fd, &buf), 0);
-    ASSERT_EQ(buf.st_size, writer->GetCowSize());
+    ASSERT_EQ(buf.st_size, writer->GetCowSizeInfo().cow_size);
 
     // Read back both operations, plus cluster op at end
     CowReader reader;
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp
index 3383a58..8cf46f4 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp
@@ -658,14 +658,14 @@
     options.compression = "none";
     auto estimator = android::snapshot::CreateCowEstimator(3, options);
     ASSERT_TRUE(estimator->AddZeroBlocks(0, 1024 * 1024));
-    const auto cow_size = estimator->GetCowSize();
+    const auto cow_size = estimator->GetCowSizeInfo().cow_size;
     options.op_count_max = 1024 * 1024;
     options.max_blocks = 1024 * 1024;
     CowWriterV3 writer(options, GetCowFd());
     ASSERT_TRUE(writer.Initialize());
     ASSERT_TRUE(writer.AddZeroBlocks(0, 1024 * 1024));
 
-    ASSERT_LE(writer.GetCowSize(), cow_size);
+    ASSERT_LE(writer.GetCowSizeInfo().cow_size, cow_size);
 }
 
 TEST_F(CowTestV3, CopyOpMany) {
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/writer_v2.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/writer_v2.cpp
index f9a4e47..75cd111 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/writer_v2.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/writer_v2.cpp
@@ -576,12 +576,14 @@
     return Sync();
 }
 
-uint64_t CowWriterV2::GetCowSize() {
+CowSizeInfo CowWriterV2::GetCowSizeInfo() const {
+    CowSizeInfo info;
     if (current_data_size_ > 0) {
-        return next_data_pos_ + sizeof(footer_);
+        info.cow_size = next_data_pos_ + sizeof(footer_);
     } else {
-        return next_op_pos_ + sizeof(footer_);
+        info.cow_size = next_op_pos_ + sizeof(footer_);
     }
+    return info;
 }
 
 bool CowWriterV2::GetDataPos(uint64_t* pos) {
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/writer_v2.h b/fs_mgr/libsnapshot/libsnapshot_cow/writer_v2.h
index 50e635f..05de2ad 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/writer_v2.h
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/writer_v2.h
@@ -27,7 +27,7 @@
 
     bool Initialize(std::optional<uint64_t> label = {}) override;
     bool Finalize() override;
-    uint64_t GetCowSize() override;
+    CowSizeInfo GetCowSizeInfo() const override;
 
   protected:
     virtual bool EmitCopy(uint64_t new_block, uint64_t old_block, uint64_t num_blocks = 1) override;
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.cpp
index d99e6e6..be6b6da 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.cpp
@@ -34,6 +34,7 @@
 #include <zlib.h>
 
 #include <fcntl.h>
+#include <libsnapshot/cow_compress.h>
 #include <libsnapshot_cow/parser_v3.h>
 #include <linux/fs.h>
 #include <sys/ioctl.h>
@@ -55,11 +56,35 @@
 
 using android::base::unique_fd;
 
+// Divide |x| by |y| and round up to the nearest integer.
+constexpr uint64_t DivRoundUp(uint64_t x, uint64_t y) {
+    return (x + y - 1) / y;
+}
+
 CowWriterV3::CowWriterV3(const CowOptions& options, unique_fd&& fd)
     : CowWriterBase(options, std::move(fd)), batch_size_(std::max<size_t>(options.cluster_ops, 1)) {
     SetupHeaders();
 }
 
+void CowWriterV3::InitWorkers() {
+    if (num_compress_threads_ <= 1) {
+        LOG_INFO << "Not creating new threads for compression.";
+        return;
+    }
+    compress_threads_.reserve(num_compress_threads_);
+    compress_threads_.clear();
+    threads_.reserve(num_compress_threads_);
+    threads_.clear();
+    for (size_t i = 0; i < num_compress_threads_; i++) {
+        std::unique_ptr<ICompressor> compressor =
+                ICompressor::Create(compression_, header_.block_size);
+        auto&& wt = compress_threads_.emplace_back(
+                std::make_unique<CompressWorker>(std::move(compressor), header_.block_size));
+        threads_.emplace_back(std::thread([wt = wt.get()]() { wt->RunThread(); }));
+    }
+    LOG(INFO) << num_compress_threads_ << " thread used for compression";
+}
+
 void CowWriterV3::SetupHeaders() {
     header_ = {};
     header_.prefix.magic = kCowMagicNumber;
@@ -135,10 +160,24 @@
     } else {
         LOG(INFO) << "Batch writes: disabled";
     }
+    if (android::base::GetBoolProperty("ro.virtual_ab.compression.threads", false) &&
+        options_.num_compress_threads) {
+        num_compress_threads_ = options_.num_compress_threads;
+    }
+    InitWorkers();
     return true;
 }
 
-CowWriterV3::~CowWriterV3() {}
+CowWriterV3::~CowWriterV3() {
+    for (const auto& t : compress_threads_) {
+        t->Finalize();
+    }
+    for (auto& t : threads_) {
+        if (t.joinable()) {
+            t.join();
+        }
+    }
+}
 
 bool CowWriterV3::Initialize(std::optional<uint64_t> label) {
     if (!InitFd() || !ParseOptions()) {
@@ -289,19 +328,24 @@
                    << " but compressor is uninitialized.";
         return false;
     }
+    const auto bytes = reinterpret_cast<const uint8_t*>(data);
     const size_t num_blocks = (size / header_.block_size);
 
     for (size_t i = 0; i < num_blocks;) {
         const auto blocks_to_write =
                 std::min<size_t>(batch_size_ - cached_data_.size(), num_blocks - i);
         size_t compressed_bytes = 0;
+        auto&& blocks = CompressBlocks(blocks_to_write, bytes + header_.block_size * i);
+        if (blocks.size() != blocks_to_write) {
+            LOG(ERROR) << "Failed to compress blocks " << new_block_start + i << ", "
+                       << blocks_to_write << ", actual number of blocks received from compressor "
+                       << blocks.size();
+            return false;
+        }
         for (size_t j = 0; j < blocks_to_write; j++) {
-            const uint8_t* const iter =
-                    reinterpret_cast<const uint8_t*>(data) + (header_.block_size * (i + j));
-
             CowOperation& op = cached_ops_.emplace_back();
             auto& vec = data_vec_.emplace_back();
-            auto& compressed_data = cached_data_.emplace_back();
+            auto& compressed_data = cached_data_.emplace_back(std::move(blocks[j]));
             op.new_block = new_block_start + i + j;
 
             op.set_type(type);
@@ -310,20 +354,6 @@
             } else {
                 op.set_source(next_data_pos_ + compressed_bytes);
             }
-            if (compression_.algorithm == kCowCompressNone) {
-                compressed_data.resize(header_.block_size);
-            } else {
-                compressed_data = compressor_->Compress(iter, header_.block_size);
-                if (compressed_data.empty()) {
-                    LOG(ERROR) << "Compression failed during EmitBlocks(" << new_block_start << ", "
-                               << num_blocks << ");";
-                    return false;
-                }
-            }
-            if (compressed_data.size() >= header_.block_size) {
-                compressed_data.resize(header_.block_size);
-                std::memcpy(compressed_data.data(), iter, header_.block_size);
-            }
             vec = {.iov_base = compressed_data.data(), .iov_len = compressed_data.size()};
             op.data_length = vec.iov_len;
             compressed_bytes += op.data_length;
@@ -392,7 +422,6 @@
 }
 
 bool CowWriterV3::EmitSequenceData(size_t num_ops, const uint32_t* data) {
-    // TODO: size sequence buffer based on options
     if (header_.op_count > 0 || !cached_ops_.empty()) {
         LOG(ERROR) << "There's " << header_.op_count << " operations written to disk and "
                    << cached_ops_.size()
@@ -400,8 +429,14 @@
                       "operation writes.";
         return false;
     }
+
     header_.sequence_data_count = num_ops;
+
+    // Ensure next_data_pos_ is updated as previously initialized + the newly added sequence buffer.
+    CHECK_EQ(next_data_pos_ + header_.sequence_data_count * sizeof(uint32_t),
+             GetDataOffset(header_));
     next_data_pos_ = GetDataOffset(header_);
+
     if (!android::base::WriteFullyAtOffset(fd_, data, sizeof(data[0]) * num_ops,
                                            GetSequenceOffset(header_))) {
         PLOG(ERROR) << "writing sequence buffer failed";
@@ -438,6 +473,57 @@
     return true;
 }
 
+std::vector<std::basic_string<uint8_t>> CowWriterV3::CompressBlocks(const size_t num_blocks,
+                                                                    const void* data) {
+    const size_t num_threads = (num_blocks == 1) ? 1 : num_compress_threads_;
+    const size_t blocks_per_thread = DivRoundUp(num_blocks, num_threads);
+    std::vector<std::basic_string<uint8_t>> compressed_buf;
+    compressed_buf.clear();
+    const uint8_t* const iter = reinterpret_cast<const uint8_t*>(data);
+    if (compression_.algorithm == kCowCompressNone) {
+        for (size_t i = 0; i < num_blocks; i++) {
+            auto& buf = compressed_buf.emplace_back();
+            buf.resize(header_.block_size);
+            std::memcpy(buf.data(), iter + i * header_.block_size, header_.block_size);
+        }
+        return compressed_buf;
+    }
+    if (num_threads <= 1) {
+        if (!CompressWorker::CompressBlocks(compressor_.get(), header_.block_size, data, num_blocks,
+                                            &compressed_buf)) {
+            return {};
+        }
+    } else {
+        // Submit the blocks per thread. The retrieval of
+        // compressed buffers has to be done in the same order.
+        // We should not poll for completed buffers in a different order as the
+        // buffers are tightly coupled with block ordering.
+        for (size_t i = 0; i < num_threads; i++) {
+            CompressWorker* worker = compress_threads_[i].get();
+            const auto blocks_in_batch =
+                    std::min(num_blocks - i * blocks_per_thread, blocks_per_thread);
+            worker->EnqueueCompressBlocks(iter + i * blocks_per_thread * header_.block_size,
+                                          blocks_in_batch);
+        }
+
+        for (size_t i = 0; i < num_threads; i++) {
+            CompressWorker* worker = compress_threads_[i].get();
+            if (!worker->GetCompressedBuffers(&compressed_buf)) {
+                return {};
+            }
+        }
+    }
+    for (size_t i = 0; i < num_blocks; i++) {
+        auto& block = compressed_buf[i];
+        if (block.size() >= header_.block_size) {
+            block.resize(header_.block_size);
+            std::memcpy(block.data(), iter + header_.block_size * i, header_.block_size);
+        }
+    }
+
+    return compressed_buf;
+}
+
 bool CowWriterV3::WriteOperation(std::basic_string_view<CowOperationV3> ops,
                                  std::basic_string_view<struct iovec> data) {
     const auto total_data_size =
@@ -491,8 +577,11 @@
     return Sync();
 }
 
-uint64_t CowWriterV3::GetCowSize() {
-    return next_data_pos_;
+CowSizeInfo CowWriterV3::GetCowSizeInfo() const {
+    CowSizeInfo info;
+    info.cow_size = next_data_pos_;
+    info.op_count_max = header_.op_count_max;
+    return info;
 }
 
 }  // namespace snapshot
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.h b/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.h
index 3a7b877..b19af60 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.h
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.h
@@ -16,6 +16,7 @@
 
 #include <android-base/logging.h>
 #include <string_view>
+#include <thread>
 #include <vector>
 
 #include "writer_base.h"
@@ -30,7 +31,7 @@
 
     bool Initialize(std::optional<uint64_t> label = {}) override;
     bool Finalize() override;
-    uint64_t GetCowSize() override;
+    CowSizeInfo GetCowSizeInfo() const override;
 
   protected:
     virtual bool EmitCopy(uint64_t new_block, uint64_t old_block, uint64_t num_blocks = 1) override;
@@ -51,12 +52,14 @@
                         std::basic_string_view<struct iovec> data);
     bool EmitBlocks(uint64_t new_block_start, const void* data, size_t size, uint64_t old_block,
                     uint16_t offset, CowOperationType type);
-    bool CompressBlocks(size_t num_blocks, const void* data);
     bool CheckOpCount(size_t op_count);
 
   private:
+    std::vector<std::basic_string<uint8_t>> CompressBlocks(const size_t num_blocks,
+                                                           const void* data);
     bool ReadBackVerification();
     bool FlushCacheOps();
+    void InitWorkers();
     CowHeaderV3 header_{};
     CowCompression compression_;
     // in the case that we are using one thread for compression, we can store and re-use the same
@@ -75,6 +78,8 @@
     std::vector<CowOperationV3> cached_ops_;
     std::vector<std::basic_string<uint8_t>> cached_data_;
     std::vector<struct iovec> data_vec_;
+
+    std::vector<std::thread> threads_;
 };
 
 }  // namespace snapshot
diff --git a/fs_mgr/libsnapshot/partition_cow_creator.cpp b/fs_mgr/libsnapshot/partition_cow_creator.cpp
index 5bc7e65..c0d2073 100644
--- a/fs_mgr/libsnapshot/partition_cow_creator.cpp
+++ b/fs_mgr/libsnapshot/partition_cow_creator.cpp
@@ -217,6 +217,7 @@
 
     if (update && update->has_estimate_cow_size()) {
         ret.snapshot_status.set_estimated_cow_size(update->estimate_cow_size());
+        ret.snapshot_status.set_estimated_ops_buffer_size(update->estimate_op_count_max());
     }
 
     if (ret.snapshot_status.snapshot_size() == 0) {
diff --git a/fs_mgr/libsnapshot/snapshot.cpp b/fs_mgr/libsnapshot/snapshot.cpp
index e33bdff..9eb41b2 100644
--- a/fs_mgr/libsnapshot/snapshot.cpp
+++ b/fs_mgr/libsnapshot/snapshot.cpp
@@ -3551,6 +3551,9 @@
                 options.scratch_space = false;
             }
             options.compression = it->second.compression_algorithm();
+            if (cow_version >= 3) {
+                options.op_count_max = it->second.estimated_ops_buffer_size();
+            }
 
             auto writer = CreateCowWriter(cow_version, options, std::move(fd));
             if (!writer->Finalize()) {
@@ -3662,9 +3665,7 @@
     cow_options.max_blocks = {status.device_size() / cow_options.block_size};
     cow_options.batch_write = status.batched_writes();
     cow_options.num_compress_threads = status.enable_threading() ? 2 : 1;
-    // TODO(b/313962438) Improve op_count estimate. For now, use number of
-    // blocks as an upper bound.
-    cow_options.op_count_max = status.device_size() / cow_options.block_size;
+    cow_options.op_count_max = status.estimated_ops_buffer_size();
     // Disable scratch space for vts tests
     if (device()->IsTestDevice()) {
         cow_options.scratch_space = false;
diff --git a/init/Android.bp b/init/Android.bp
index e5512e6..a781d8b 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -188,7 +188,6 @@
         "libfs_mgr",
         "libgsi",
         "libhidl-gen-utils",
-        "libkeyutils",
         "liblog",
         "liblogwrap",
         "liblp",
diff --git a/init/builtins.cpp b/init/builtins.cpp
index a95a4a3..606ea8c 100644
--- a/init/builtins.cpp
+++ b/init/builtins.cpp
@@ -592,9 +592,6 @@
     } else if (code == FS_MGR_MNTALL_DEV_FILE_ENCRYPTED ||
                code == FS_MGR_MNTALL_DEV_IS_METADATA_ENCRYPTED ||
                code == FS_MGR_MNTALL_DEV_NEEDS_METADATA_ENCRYPTION) {
-        if (!FscryptInstallKeyring()) {
-            return Error() << "FscryptInstallKeyring() failed";
-        }
         SetProperty("ro.crypto.state", "encrypted");
 
         // Although encrypted, vold has already set the device up, so we do not need to
diff --git a/init/fscrypt_init_extensions.cpp b/init/fscrypt_init_extensions.cpp
index fbd8189..6a561e5 100644
--- a/init/fscrypt_init_extensions.cpp
+++ b/init/fscrypt_init_extensions.cpp
@@ -34,28 +34,12 @@
 #include <cutils/properties.h>
 #include <cutils/sockets.h>
 #include <fscrypt/fscrypt.h>
-#include <keyutils.h>
 #include <logwrap/logwrap.h>
 
 #define TAG "fscrypt"
 
 using namespace android::fscrypt;
 
-bool FscryptInstallKeyring() {
-    if (keyctl_search(KEY_SPEC_SESSION_KEYRING, "keyring", "fscrypt", 0) != -1) {
-        LOG(INFO) << "Keyring is already created";
-        return true;
-    }
-    key_serial_t device_keyring = add_key("keyring", "fscrypt", 0, 0, KEY_SPEC_SESSION_KEYRING);
-
-    if (device_keyring == -1) {
-        PLOG(ERROR) << "Failed to create keyring";
-        return false;
-    }
-    LOG(INFO) << "Keyring created with id " << device_keyring << " in process " << getpid();
-    return true;
-}
-
 // TODO(b/139378601): use a single central implementation of this.
 static void delete_dir_contents(const std::string& dir) {
     char* const paths[2] = {const_cast<char*>(dir.c_str()), nullptr};
diff --git a/init/fscrypt_init_extensions.h b/init/fscrypt_init_extensions.h
index d357bb2..5e0269a 100644
--- a/init/fscrypt_init_extensions.h
+++ b/init/fscrypt_init_extensions.h
@@ -25,6 +25,5 @@
     kDeleteIfNecessary,
 };
 
-bool FscryptInstallKeyring();
 bool FscryptSetDirectoryPolicy(const std::string& ref_basename, FscryptAction action,
                                const std::string& dir);
diff --git a/init/fuzzer/Android.bp b/init/fuzzer/Android.bp
index 856ca8c..9916246 100644
--- a/init/fuzzer/Android.bp
+++ b/init/fuzzer/Android.bp
@@ -32,7 +32,6 @@
         "libbase",
         "libfs_mgr",
         "libhidl-gen-utils",
-        "libkeyutils",
         "liblog",
         "libprocessgroup",
         "libselinux",
diff --git a/init/init.cpp b/init/init.cpp
index aeccd66..19e909f 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -54,7 +54,6 @@
 #include <android-base/thread_annotations.h>
 #include <fs_avb/fs_avb.h>
 #include <fs_mgr_vendor_overlay.h>
-#include <keyutils.h>
 #include <libavb/libavb.h>
 #include <libgsi/libgsi.h>
 #include <libsnapshot/snapshot.h>
@@ -971,11 +970,6 @@
                    << " to /proc/1/oom_score_adj: " << result.error();
     }
 
-    // Set up a session keyring that all processes will have access to. It
-    // will hold things like FBE encryption keys. No process should override
-    // its session keyring.
-    keyctl_get_keyring_ID(KEY_SPEC_SESSION_KEYRING, 1);
-
     // Indicate that booting is in progress to background fw loaders, etc.
     close(open("/dev/.booting", O_WRONLY | O_CREAT | O_CLOEXEC, 0000));
 
diff --git a/libvendorsupport/Android.bp b/libvendorsupport/Android.bp
new file mode 100644
index 0000000..16a4c4c
--- /dev/null
+++ b/libvendorsupport/Android.bp
@@ -0,0 +1,35 @@
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+cc_library {
+    name: "libvendorsupport",
+    native_bridge_supported: true,
+    llndk: {
+        symbol_file: "libvendorsupport.map.txt",
+    },
+    srcs: ["version_props.c"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
+    local_include_dirs: ["include/vendorsupport"],
+    export_include_dirs: ["include"],
+    shared_libs: [
+        "liblog",
+    ],
+}
diff --git a/libvendorsupport/OWNERS b/libvendorsupport/OWNERS
new file mode 100644
index 0000000..2ab18eb
--- /dev/null
+++ b/libvendorsupport/OWNERS
@@ -0,0 +1,2 @@
+jiyong@google.com
+justinyun@google.com
diff --git a/libvendorsupport/TEST_MAPPING b/libvendorsupport/TEST_MAPPING
new file mode 100644
index 0000000..5bd09ba
--- /dev/null
+++ b/libvendorsupport/TEST_MAPPING
@@ -0,0 +1,7 @@
+{
+  "postsubmit": [
+    {
+      "name": "libvendorsupport-tests"
+    }
+  ]
+}
diff --git a/libvendorsupport/include/vendorsupport/api_level.h b/libvendorsupport/include/vendorsupport/api_level.h
new file mode 100644
index 0000000..ba1a6b8
--- /dev/null
+++ b/libvendorsupport/include/vendorsupport/api_level.h
@@ -0,0 +1,51 @@
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include <android/api-level.h>
+
+#define __ANDROID_VENDOR_API_MAX__ 1000000
+#define __INVALID_API_LEVEL -1
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Find corresponding vendor API level from an SDK API version.
+ *
+ * @details
+ * SDK API versions and vendor API levels are not compatible and not
+ * convertible. However, this function can be used to compare the two versions
+ * to know which one is newer than the other.
+ *
+ * @param sdk_api_level The SDK version int. This must be less than 10000.
+ * @return The corresponding vendor API level of the SDK version. -1 if the SDK
+ * version is invalid or 10000.
+ */
+int vendor_api_level_of(int sdk_api_level);
+
+/**
+ * @brief Find corresponding SDK API version from a vendor API level.
+ *
+ * @param vendor_api_level The vendor API level int.
+ * @return The corresponding SDK API version of the vendor API level. -1 if the
+ * vendor API level is invalid.
+ */
+int sdk_api_level_of(int vendor_api_level);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/libvendorsupport/libvendorsupport.map.txt b/libvendorsupport/libvendorsupport.map.txt
new file mode 100644
index 0000000..9a23b94
--- /dev/null
+++ b/libvendorsupport/libvendorsupport.map.txt
@@ -0,0 +1,7 @@
+LIBVENDORSUPPORT {
+  global:
+    vendor_api_level_of; # llndk systemapi
+    sdk_api_level_of; # llndk systemapi
+  local:
+    *;
+};
diff --git a/libvendorsupport/tests/Android.bp b/libvendorsupport/tests/Android.bp
new file mode 100644
index 0000000..42e3371
--- /dev/null
+++ b/libvendorsupport/tests/Android.bp
@@ -0,0 +1,33 @@
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+cc_test {
+    name: "libvendorsupport-tests",
+    srcs: [
+        "version_props_test.cpp",
+    ],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
+    shared_libs: [
+        "libvendorsupport",
+    ],
+    test_suites: ["general-tests"],
+}
+
diff --git a/libvendorsupport/tests/version_props_test.cpp b/libvendorsupport/tests/version_props_test.cpp
new file mode 100644
index 0000000..538a2e2
--- /dev/null
+++ b/libvendorsupport/tests/version_props_test.cpp
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <gtest/gtest.h>
+
+#include <vendorsupport/api_level.h>
+
+using namespace std;
+
+namespace {
+
+TEST(vendorsupport, get_corresponding_vendor_api_level) {
+    ASSERT_EQ(__ANDROID_API_U__, vendor_api_level_of(__ANDROID_API_U__));
+    ASSERT_EQ(202404, vendor_api_level_of(__ANDROID_API_V__));
+    ASSERT_EQ(__INVALID_API_LEVEL, vendor_api_level_of(__ANDROID_API_FUTURE__));
+}
+
+TEST(vendorsupport, get_corresponding_sdk_api_level) {
+    ASSERT_EQ(__ANDROID_API_U__, sdk_api_level_of(__ANDROID_API_U__));
+    ASSERT_EQ(__ANDROID_API_V__, sdk_api_level_of(202404));
+    ASSERT_EQ(__INVALID_API_LEVEL, sdk_api_level_of(__ANDROID_VENDOR_API_MAX__));
+    ASSERT_EQ(__INVALID_API_LEVEL, sdk_api_level_of(35));
+}
+
+}  // namespace
\ No newline at end of file
diff --git a/libvendorsupport/version_props.c b/libvendorsupport/version_props.c
new file mode 100644
index 0000000..4d0e45e
--- /dev/null
+++ b/libvendorsupport/version_props.c
@@ -0,0 +1,41 @@
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "api_level.h"
+
+#include <log/log.h>
+
+int vendor_api_level_of(int sdk_api_level) {
+    if (sdk_api_level < __ANDROID_API_V__) {
+        return sdk_api_level;
+    }
+    // In Android V, vendor API level started with version 202404.
+    // The calculation assumes that the SDK api level bumps once a year.
+    if (sdk_api_level < __ANDROID_API_FUTURE__) {
+        return 202404 + ((sdk_api_level - __ANDROID_API_V__) * 100);
+    }
+    ALOGE("The SDK version must be less than 10000: %d", sdk_api_level);
+    return __INVALID_API_LEVEL;
+}
+
+int sdk_api_level_of(int vendor_api_level) {
+    if (vendor_api_level < __ANDROID_API_V__) {
+        return vendor_api_level;
+    }
+    if (vendor_api_level >= 202404 && vendor_api_level < __ANDROID_VENDOR_API_MAX__) {
+        return (vendor_api_level - 202404) / 100 + __ANDROID_API_V__;
+    }
+    ALOGE("Unexpected vendor api level: %d", vendor_api_level);
+    return __INVALID_API_LEVEL;
+}
diff --git a/property_service/libpropertyinfoparser/Android.bp b/property_service/libpropertyinfoparser/Android.bp
index 87646f9..b4a16d3 100644
--- a/property_service/libpropertyinfoparser/Android.bp
+++ b/property_service/libpropertyinfoparser/Android.bp
@@ -25,4 +25,8 @@
         },
     },
     export_include_dirs: ["include"],
+    apex_available: [
+        "//apex_available:platform",
+        "com.android.runtime",
+    ],
 }