diff --git a/fs_mgr/fs_mgr_fstab.cpp b/fs_mgr/fs_mgr_fstab.cpp
index 4dbacd7..e50f7c3 100644
--- a/fs_mgr/fs_mgr_fstab.cpp
+++ b/fs_mgr/fs_mgr_fstab.cpp
@@ -36,6 +36,7 @@
 
 #include "fs_mgr_priv.h"
 
+using android::base::EndsWith;
 using android::base::ParseByteCount;
 using android::base::ParseInt;
 using android::base::ReadFileToString;
@@ -598,7 +599,7 @@
     return boot_devices;
 }
 
-FstabEntry BuildGsiUserdataFstabEntry() {
+FstabEntry BuildDsuUserdataFstabEntry() {
     constexpr uint32_t kFlags = MS_NOATIME | MS_NOSUID | MS_NODEV;
 
     FstabEntry userdata = {
@@ -627,7 +628,12 @@
     return false;
 }
 
-void TransformFstabForGsi(Fstab* fstab) {
+}  // namespace
+
+void TransformFstabForDsu(Fstab* fstab, const std::vector<std::string>& dsu_partitions) {
+    static constexpr char kGsiKeys[] =
+            "/avb/q-gsi.avbpubkey:/avb/r-gsi.avbpubkey:/avb/s-gsi.avbpubkey";
+    // Convert userdata
     // Inherit fstab properties for userdata.
     FstabEntry userdata;
     if (FstabEntry* entry = GetEntryForMountPoint(fstab, "/data")) {
@@ -639,19 +645,75 @@
             userdata.key_dir += "/gsi";
         }
     } else {
-        userdata = BuildGsiUserdataFstabEntry();
-    }
-
-    if (EraseFstabEntry(fstab, "/system")) {
-        fstab->emplace_back(BuildGsiSystemFstabEntry());
+        userdata = BuildDsuUserdataFstabEntry();
     }
 
     if (EraseFstabEntry(fstab, "/data")) {
         fstab->emplace_back(userdata);
     }
-}
 
-}  // namespace
+    // Convert others
+    for (auto&& partition : dsu_partitions) {
+        if (!EndsWith(partition, gsi::kDsuPostfix)) {
+            continue;
+        }
+        // userdata has been handled
+        if (StartsWith(partition, "user")) {
+            continue;
+        }
+        // dsu_partition_name = corresponding_partition_name + kDsuPostfix
+        // e.g.
+        //    system_gsi for system
+        //    product_gsi for product
+        //    vendor_gsi for vendor
+        std::string lp_name = partition.substr(0, partition.length() - strlen(gsi::kDsuPostfix));
+        std::string mount_point = "/" + lp_name;
+        std::vector<FstabEntry*> entries = GetEntriesForMountPoint(fstab, mount_point);
+        if (entries.empty()) {
+            FstabEntry entry = {
+                    .blk_device = partition,
+                    .mount_point = mount_point,
+                    .fs_type = "ext4",
+                    .flags = MS_RDONLY,
+                    .fs_options = "barrier=1",
+                    .avb_keys = kGsiKeys,
+                    // .logical_partition_name is required to look up AVB Hashtree descriptors.
+                    .logical_partition_name = "system"};
+            entry.fs_mgr_flags.wait = true;
+            entry.fs_mgr_flags.logical = true;
+            entry.fs_mgr_flags.first_stage_mount = true;
+            // Use the system key which may be in the vbmeta or vbmeta_system
+            // TODO: b/141284191
+            entry.vbmeta_partition = "vbmeta";
+            fstab->emplace_back(entry);
+            entry.vbmeta_partition = "vbmeta_system";
+            fstab->emplace_back(entry);
+        } else {
+            // If the corresponding partition exists, transform all its Fstab
+            // by pointing .blk_device to the DSU partition.
+            for (auto&& entry : entries) {
+                entry->blk_device = partition;
+                if (entry->avb_keys.size() > 0) {
+                    entry->avb_keys += ":";
+                }
+                // If the DSU is signed by OEM, the original Fstab already has the information
+                // required by avb, otherwise the DSU is GSI and will need the avb_keys as listed
+                // below.
+                entry->avb_keys += kGsiKeys;
+            }
+            // Make sure the ext4 is included to support GSI.
+            auto partition_ext4 =
+                    std::find_if(fstab->begin(), fstab->end(), [&](const auto& entry) {
+                        return entry.mount_point == mount_point && entry.fs_type == "ext4";
+                    });
+            if (partition_ext4 == fstab->end()) {
+                auto new_entry = *GetEntryForMountPoint(fstab, mount_point);
+                new_entry.fs_type = "ext4";
+                fstab->emplace_back(new_entry);
+            }
+        }
+    }
+}
 
 bool ReadFstabFromFile(const std::string& path, Fstab* fstab) {
     auto fstab_file = std::unique_ptr<FILE, decltype(&fclose)>{fopen(path.c_str(), "re"), fclose};
@@ -667,7 +729,9 @@
         return false;
     }
     if (!is_proc_mounts && !access(android::gsi::kGsiBootedIndicatorFile, F_OK)) {
-        TransformFstabForGsi(fstab);
+        std::string lp_names;
+        ReadFileToString(gsi::kGsiLpNamesFile, &lp_names);
+        TransformFstabForDsu(fstab, Split(lp_names, ","));
     }
 
     SkipMountingPartitions(fstab);
@@ -779,6 +843,21 @@
     return nullptr;
 }
 
+std::vector<FstabEntry*> GetEntriesForMountPoint(Fstab* fstab, const std::string& path) {
+    std::vector<FstabEntry*> entries;
+    if (fstab == nullptr) {
+        return entries;
+    }
+
+    for (auto& entry : *fstab) {
+        if (entry.mount_point == path) {
+            entries.emplace_back(&entry);
+        }
+    }
+
+    return entries;
+}
+
 std::set<std::string> GetBootDevices() {
     // First check the kernel commandline, then try the device tree otherwise
     std::string dt_file_name = get_android_dt_dir() + "/boot_devices";
@@ -798,23 +877,6 @@
     return ExtraBootDevices(fstab);
 }
 
-FstabEntry BuildGsiSystemFstabEntry() {
-    // .logical_partition_name is required to look up AVB Hashtree descriptors.
-    FstabEntry system = {
-            .blk_device = "system_gsi",
-            .mount_point = "/system",
-            .fs_type = "ext4",
-            .flags = MS_RDONLY,
-            .fs_options = "barrier=1",
-            // could add more keys separated by ':'.
-            .avb_keys = "/avb/q-gsi.avbpubkey:/avb/r-gsi.avbpubkey:/avb/s-gsi.avbpubkey",
-            .logical_partition_name = "system"};
-    system.fs_mgr_flags.wait = true;
-    system.fs_mgr_flags.logical = true;
-    system.fs_mgr_flags.first_stage_mount = true;
-    return system;
-}
-
 std::string GetVerityDeviceName(const FstabEntry& entry) {
     std::string base_device;
     if (entry.mount_point == "/") {
diff --git a/fs_mgr/include_fstab/fstab/fstab.h b/fs_mgr/include_fstab/fstab/fstab.h
index c7193ab..d999ae1 100644
--- a/fs_mgr/include_fstab/fstab/fstab.h
+++ b/fs_mgr/include_fstab/fstab/fstab.h
@@ -101,9 +101,18 @@
 bool SkipMountingPartitions(Fstab* fstab);
 
 FstabEntry* GetEntryForMountPoint(Fstab* fstab, const std::string& path);
+// The Fstab can contain multiple entries for the same mount point with different configurations.
+std::vector<FstabEntry*> GetEntriesForMountPoint(Fstab* fstab, const std::string& path);
 
-// Helper method to build a GSI fstab entry for mounting /system.
-FstabEntry BuildGsiSystemFstabEntry();
+// This method builds DSU fstab entries and transfer the fstab.
+//
+// fstab points to the unmodified fstab.
+//
+// dsu_partitions contains partition names, e.g.
+//     dsu_partitions[0] = "system_gsi"
+//     dsu_partitions[1] = "userdata_gsi"
+//     dsu_partitions[2] = ...
+void TransformFstabForDsu(Fstab* fstab, const std::vector<std::string>& dsu_partitions);
 
 std::set<std::string> GetBootDevices();
 
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
index aeeb4aa..6130a10 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
@@ -19,6 +19,7 @@
 #include <chrono>
 #include <map>
 #include <memory>
+#include <ostream>
 #include <string>
 #include <string_view>
 #include <vector>
@@ -84,6 +85,7 @@
     // operation via fastboot. This state can only be returned by WaitForMerge.
     Cancelled
 };
+std::ostream& operator<<(std::ostream& os, UpdateState state);
 
 class SnapshotManager final {
     using CreateLogicalPartitionParams = android::fs_mgr::CreateLogicalPartitionParams;
@@ -125,8 +127,9 @@
     // will fail if GetUpdateState() != None.
     bool BeginUpdate();
 
-    // Cancel an update; any snapshots will be deleted. This will fail if the
-    // state != Initiated or None.
+    // Cancel an update; any snapshots will be deleted. This is allowed if the
+    // state == Initiated, None, or Unverified (before rebooting to the new
+    // slot).
     bool CancelUpdate();
 
     // Mark snapshot writes as having completed. After this, new snapshots cannot
@@ -393,6 +396,13 @@
     // The reverse of MapPartitionWithSnapshot.
     bool UnmapPartitionWithSnapshot(LockedFile* lock, const std::string& target_partition_name);
 
+    // If there isn't a previous update, return true. |needs_merge| is set to false.
+    // If there is a previous update but the device has not boot into it, tries to cancel the
+    //   update and delete any snapshots. Return true if successful. |needs_merge| is set to false.
+    // If there is a previous update and the device has boot into it, do nothing and return true.
+    //   |needs_merge| is set to true.
+    bool TryCancelUpdate(bool* needs_merge);
+
     std::string gsid_dir_;
     std::string metadata_dir_;
     std::unique_ptr<IDeviceInfo> device_;
diff --git a/fs_mgr/libsnapshot/snapshot.cpp b/fs_mgr/libsnapshot/snapshot.cpp
index b5b3af3..803bdb5 100644
--- a/fs_mgr/libsnapshot/snapshot.cpp
+++ b/fs_mgr/libsnapshot/snapshot.cpp
@@ -131,6 +131,16 @@
 }
 
 bool SnapshotManager::BeginUpdate() {
+    bool needs_merge = false;
+    if (!TryCancelUpdate(&needs_merge)) {
+        return false;
+    }
+    if (needs_merge) {
+        LOG(INFO) << "Wait for merge (if any) before beginning a new update.";
+        auto state = ProcessUpdateState();
+        LOG(INFO) << "Merged with state = " << state;
+    }
+
     auto file = LockExclusive();
     if (!file) return false;
 
@@ -143,6 +153,19 @@
 }
 
 bool SnapshotManager::CancelUpdate() {
+    bool needs_merge = false;
+    if (!TryCancelUpdate(&needs_merge)) {
+        return false;
+    }
+    if (needs_merge) {
+        LOG(ERROR) << "Cannot cancel update after it has completed or started merging";
+    }
+    return !needs_merge;
+}
+
+bool SnapshotManager::TryCancelUpdate(bool* needs_merge) {
+    *needs_merge = false;
+
     auto file = LockExclusive();
     if (!file) return false;
 
@@ -167,8 +190,8 @@
             return RemoveAllUpdateState(file.get());
         }
     }
-    LOG(ERROR) << "Cannot cancel update after it has completed or started merging";
-    return false;
+    *needs_merge = true;
+    return true;
 }
 
 bool SnapshotManager::RemoveAllUpdateState(LockedFile* lock) {
@@ -1526,34 +1549,33 @@
     }
 }
 
-bool SnapshotManager::WriteUpdateState(LockedFile* file, UpdateState state) {
-    std::string contents;
+std::ostream& operator<<(std::ostream& os, UpdateState state) {
     switch (state) {
         case UpdateState::None:
-            contents = "none";
-            break;
+            return os << "none";
         case UpdateState::Initiated:
-            contents = "initiated";
-            break;
+            return os << "initiated";
         case UpdateState::Unverified:
-            contents = "unverified";
-            break;
+            return os << "unverified";
         case UpdateState::Merging:
-            contents = "merging";
-            break;
+            return os << "merging";
         case UpdateState::MergeCompleted:
-            contents = "merge-completed";
-            break;
+            return os << "merge-completed";
         case UpdateState::MergeNeedsReboot:
-            contents = "merge-needs-reboot";
-            break;
+            return os << "merge-needs-reboot";
         case UpdateState::MergeFailed:
-            contents = "merge-failed";
-            break;
+            return os << "merge-failed";
         default:
             LOG(ERROR) << "Unknown update state";
-            return false;
+            return os;
     }
+}
+
+bool SnapshotManager::WriteUpdateState(LockedFile* file, UpdateState state) {
+    std::stringstream ss;
+    ss << state;
+    std::string contents = ss.str();
+    if (contents.empty()) return false;
 
     if (!Truncate(file)) return false;
     if (!android::base::WriteStringToFd(contents, file->fd())) {
diff --git a/fs_mgr/libsnapshot/snapshot_test.cpp b/fs_mgr/libsnapshot/snapshot_test.cpp
index 36982a9..bc764fd 100644
--- a/fs_mgr/libsnapshot/snapshot_test.cpp
+++ b/fs_mgr/libsnapshot/snapshot_test.cpp
@@ -761,8 +761,7 @@
 // Also test UnmapUpdateSnapshot unmaps everything.
 // Also test first stage mount and merge after this.
 TEST_F(SnapshotUpdateTest, FullUpdateFlow) {
-    // OTA client calls CancelUpdate then BeginUpdate before doing anything.
-    ASSERT_TRUE(sm->CancelUpdate());
+    // OTA client calls BeginUpdate before doing anything.
     ASSERT_TRUE(sm->BeginUpdate());
 
     // OTA client blindly unmaps all partitions that are possibly mapped.
diff --git a/init/first_stage_mount.cpp b/init/first_stage_mount.cpp
index 4a1bc5a..9121bac 100644
--- a/init/first_stage_mount.cpp
+++ b/init/first_stage_mount.cpp
@@ -50,12 +50,13 @@
 using android::fs_mgr::AvbHandleStatus;
 using android::fs_mgr::AvbHashtreeResult;
 using android::fs_mgr::AvbUniquePtr;
-using android::fs_mgr::BuildGsiSystemFstabEntry;
 using android::fs_mgr::Fstab;
 using android::fs_mgr::FstabEntry;
 using android::fs_mgr::ReadDefaultFstab;
 using android::fs_mgr::ReadFstabFromDt;
 using android::fs_mgr::SkipMountingPartitions;
+using android::fs_mgr::TransformFstabForDsu;
+using android::init::WriteFile;
 using android::snapshot::SnapshotManager;
 
 using namespace std::literals;
@@ -596,14 +597,14 @@
 }
 
 void FirstStageMount::UseGsiIfPresent() {
-    std::string metadata_file, error;
+    std::string error;
 
-    if (!android::gsi::CanBootIntoGsi(&metadata_file, &error)) {
+    if (!android::gsi::CanBootIntoGsi(&error)) {
         LOG(INFO) << "GSI " << error << ", proceeding with normal boot";
         return;
     }
 
-    auto metadata = android::fs_mgr::ReadFromImageFile(metadata_file.c_str());
+    auto metadata = android::fs_mgr::ReadFromImageFile(gsi::kDsuLpMetadataFile);
     if (!metadata) {
         LOG(ERROR) << "GSI partition layout could not be read";
         return;
@@ -627,14 +628,16 @@
         return;
     }
 
-    // Replace the existing system fstab entry.
-    auto system_partition = std::find_if(fstab_.begin(), fstab_.end(), [](const auto& entry) {
-        return entry.mount_point == "/system";
-    });
-    if (system_partition != fstab_.end()) {
-        fstab_.erase(system_partition);
+    std::string lp_names = "";
+    std::vector<std::string> dsu_partitions;
+    for (auto&& partition : metadata->partitions) {
+        auto name = fs_mgr::GetPartitionName(partition);
+        dsu_partitions.push_back(name);
+        lp_names += name + ",";
     }
-    fstab_.emplace_back(BuildGsiSystemFstabEntry());
+    // Publish the logical partition names for TransformFstabForDsu
+    WriteFile(gsi::kGsiLpNamesFile, lp_names);
+    TransformFstabForDsu(&fstab_, dsu_partitions);
     gsi_not_on_userdata_ = (super_name != "userdata");
 }
 
diff --git a/property_service/libpropertyinfoserializer/Android.bp b/property_service/libpropertyinfoserializer/Android.bp
index 51c1226..e12be31 100644
--- a/property_service/libpropertyinfoserializer/Android.bp
+++ b/property_service/libpropertyinfoserializer/Android.bp
@@ -10,6 +10,8 @@
     ],
     static_libs: [
         "libpropertyinfoparser",
+    ],
+    shared_libs: [
         "libbase",
     ],
 }