diff --git a/fs_mgr/liblp/builder.cpp b/fs_mgr/liblp/builder.cpp
index c37d70e..dff31b0 100644
--- a/fs_mgr/liblp/builder.cpp
+++ b/fs_mgr/liblp/builder.cpp
@@ -31,6 +31,22 @@
 namespace android {
 namespace fs_mgr {
 
+std::ostream& operator<<(std::ostream& os, const Extent& extent) {
+    switch (extent.GetExtentType()) {
+        case ExtentType::kZero: {
+            os << "type: Zero";
+            break;
+        }
+        case ExtentType::kLinear: {
+            auto linear_extent = static_cast<const LinearExtent*>(&extent);
+            os << "type: Linear, physical sectors: " << linear_extent->physical_sector()
+               << ", end sectors: " << linear_extent->end_sector();
+            break;
+        }
+    }
+    return os;
+}
+
 bool LinearExtent::AddTo(LpMetadata* out) const {
     if (device_index_ >= out->block_devices.size()) {
         LERROR << "Extent references unknown block device.";
@@ -41,6 +57,17 @@
     return true;
 }
 
+bool LinearExtent::operator==(const android::fs_mgr::Extent& other) const {
+    if (other.GetExtentType() != ExtentType::kLinear) {
+        return false;
+    }
+
+    auto other_ptr = static_cast<const LinearExtent*>(&other);
+    return num_sectors_ == other_ptr->num_sectors_ &&
+           physical_sector_ == other_ptr->physical_sector_ &&
+           device_index_ == other_ptr->device_index_;
+}
+
 bool LinearExtent::OverlapsWith(const LinearExtent& other) const {
     if (device_index_ != other.device_index()) {
         return false;
@@ -64,6 +91,10 @@
     return true;
 }
 
+bool ZeroExtent::operator==(const android::fs_mgr::Extent& other) const {
+    return other.GetExtentType() == ExtentType::kZero && num_sectors_ == other.num_sectors();
+}
+
 Partition::Partition(std::string_view name, std::string_view group_name, uint32_t attributes)
     : name_(name), group_name_(group_name), attributes_(attributes), size_(0) {}
 
@@ -511,7 +542,7 @@
     return partitions_.back().get();
 }
 
-Partition* MetadataBuilder::FindPartition(std::string_view name) {
+Partition* MetadataBuilder::FindPartition(std::string_view name) const {
     for (const auto& partition : partitions_) {
         if (partition->name() == name) {
             return partition.get();
@@ -520,7 +551,7 @@
     return nullptr;
 }
 
-PartitionGroup* MetadataBuilder::FindGroup(std::string_view group_name) {
+PartitionGroup* MetadataBuilder::FindGroup(std::string_view group_name) const {
     for (const auto& group : groups_) {
         if (group->name() == group_name) {
             return group.get();
@@ -1263,5 +1294,50 @@
     return geometry_.logical_block_size;
 }
 
+bool MetadataBuilder::VerifyExtentsAgainstSourceMetadata(
+        const MetadataBuilder& source_metadata, uint32_t source_slot_number,
+        const MetadataBuilder& target_metadata, uint32_t target_slot_number,
+        const std::vector<std::string>& partitions) {
+    for (const auto& base_name : partitions) {
+        // Find the partition in metadata with the slot suffix.
+        auto target_partition_name = base_name + SlotSuffixForSlotNumber(target_slot_number);
+        const auto target_partition = target_metadata.FindPartition(target_partition_name);
+        if (!target_partition) {
+            LERROR << "Failed to find partition " << target_partition_name << " in metadata slot "
+                   << target_slot_number;
+            return false;
+        }
+
+        auto source_partition_name = base_name + SlotSuffixForSlotNumber(source_slot_number);
+        const auto source_partition = source_metadata.FindPartition(source_partition_name);
+        if (!source_partition) {
+            LERROR << "Failed to find partition " << source_partition << " in metadata slot "
+                   << source_slot_number;
+            return false;
+        }
+
+        // We expect the partitions in the target metadata to have the identical extents as the
+        // one in the source metadata. Because they are copied in NewForUpdate.
+        if (target_partition->extents().size() != source_partition->extents().size()) {
+            LERROR << "Extents count mismatch for partition " << base_name << " target slot has "
+                   << target_partition->extents().size() << ", source slot has "
+                   << source_partition->extents().size();
+            return false;
+        }
+
+        for (size_t i = 0; i < target_partition->extents().size(); i++) {
+            const auto& src_extent = *source_partition->extents()[i];
+            const auto& tgt_extent = *target_partition->extents()[i];
+            if (tgt_extent != src_extent) {
+                LERROR << "Extents " << i << " is different for partition " << base_name;
+                LERROR << "tgt extent " << tgt_extent << "; src extent " << src_extent;
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+
 }  // namespace fs_mgr
 }  // namespace android
diff --git a/fs_mgr/liblp/builder_test.cpp b/fs_mgr/liblp/builder_test.cpp
index 1a3250a..a21e09e 100644
--- a/fs_mgr/liblp/builder_test.cpp
+++ b/fs_mgr/liblp/builder_test.cpp
@@ -947,9 +947,10 @@
 }
 
 static void AddPartition(const std::unique_ptr<MetadataBuilder>& builder,
-                         const std::string& partition_name, uint64_t num_sectors,
-                         uint64_t start_sector, std::vector<Interval>* intervals) {
-    Partition* p = builder->AddPartition(partition_name, "group", 0);
+                         const std::string& partition_name, const std::string& group_name,
+                         uint64_t num_sectors, uint64_t start_sector,
+                         std::vector<Interval>* intervals = nullptr) {
+    Partition* p = builder->AddPartition(partition_name, group_name, 0);
     ASSERT_NE(p, nullptr);
     ASSERT_TRUE(builder->AddLinearExtent(p, "super", num_sectors, start_sector));
     ASSERT_EQ(p->extents().size(), 1);
@@ -977,17 +978,17 @@
     ASSERT_TRUE(builder->AddGroup("group", 0));
 
     std::vector<Interval> old_intervals;
-    AddPartition(builder, "system", 10229008, 2048, &old_intervals);
-    AddPartition(builder, "test_a", 648, 12709888, &old_intervals);
-    AddPartition(builder, "test_b", 625184, 12711936, &old_intervals);
-    AddPartition(builder, "test_c", 130912, 13338624, &old_intervals);
-    AddPartition(builder, "test_d", 888, 13469696, &old_intervals);
-    AddPartition(builder, "test_e", 888, 13471744, &old_intervals);
-    AddPartition(builder, "test_f", 888, 13475840, &old_intervals);
-    AddPartition(builder, "test_g", 888, 13477888, &old_intervals);
+    AddPartition(builder, "system", "group", 10229008, 2048, &old_intervals);
+    AddPartition(builder, "test_a", "group", 648, 12709888, &old_intervals);
+    AddPartition(builder, "test_b", "group", 625184, 12711936, &old_intervals);
+    AddPartition(builder, "test_c", "group", 130912, 13338624, &old_intervals);
+    AddPartition(builder, "test_d", "group", 888, 13469696, &old_intervals);
+    AddPartition(builder, "test_e", "group", 888, 13471744, &old_intervals);
+    AddPartition(builder, "test_f", "group", 888, 13475840, &old_intervals);
+    AddPartition(builder, "test_g", "group", 888, 13477888, &old_intervals);
 
     // Don't track the first vendor interval, since it will get extended.
-    AddPartition(builder, "vendor", 2477920, 10231808, nullptr);
+    AddPartition(builder, "vendor", "group", 2477920, 10231808, nullptr);
 
     std::vector<Interval> new_intervals;
 
@@ -1066,3 +1067,30 @@
     ASSERT_NE(p, nullptr);
     ASSERT_FALSE(builder->ResizePartition(p, 18446744073709551615ULL));
 }
+
+TEST_F(BuilderTest, VerifyExtent) {
+    auto source_builder = MetadataBuilder::New(4096 * 50, 40960, 2);
+    ASSERT_NE(source_builder, nullptr);
+    ASSERT_TRUE(source_builder->AddGroup("test_group_a", 40960));
+    ASSERT_TRUE(source_builder->AddGroup("test_group_b", 40960));
+    AddPartition(source_builder, "system_a", "test_group_a", 8192, 2048);
+    AddPartition(source_builder, "vendor_a", "test_group_a", 10240, 10240);
+    AddPartition(source_builder, "system_b", "test_group_b", 8192, 20480);
+
+    auto target_builder = MetadataBuilder::New(4096 * 50, 40960, 2);
+    ASSERT_NE(target_builder, nullptr);
+    ASSERT_TRUE(target_builder->AddGroup("test_group_b", 40960));
+    AddPartition(target_builder, "system_b", "test_group_b", 8192, 2048);
+    AddPartition(target_builder, "vendor_b", "test_group_b", 10240, 10240);
+
+    ASSERT_TRUE(MetadataBuilder::VerifyExtentsAgainstSourceMetadata(
+            *source_builder, 0, *target_builder, 1, std::vector<std::string>{"system", "vendor"}));
+
+    target_builder->RemovePartition("vendor_b");
+    ASSERT_FALSE(target_builder->VerifyExtentsAgainstSourceMetadata(
+            *source_builder, 0, *target_builder, 1, std::vector<std::string>{"vendor"}));
+
+    AddPartition(target_builder, "vendor_b", "test_group_b", 1000, 10240);
+    ASSERT_FALSE(target_builder->VerifyExtentsAgainstSourceMetadata(
+            *source_builder, 0, *target_builder, 1, std::vector<std::string>{"vendor"}));
+}
diff --git a/fs_mgr/liblp/include/liblp/builder.h b/fs_mgr/liblp/include/liblp/builder.h
index 89a47b1..293e444 100644
--- a/fs_mgr/liblp/include/liblp/builder.h
+++ b/fs_mgr/liblp/include/liblp/builder.h
@@ -42,6 +42,11 @@
 // Name of the default group in a metadata.
 static constexpr std::string_view kDefaultGroup = "default";
 
+enum class ExtentType {
+    kZero,
+    kLinear,
+};
+
 // Abstraction around dm-targets that can be encoded into logical partition tables.
 class Extent {
   public:
@@ -50,6 +55,10 @@
 
     virtual bool AddTo(LpMetadata* out) const = 0;
     virtual LinearExtent* AsLinearExtent() { return nullptr; }
+    virtual ExtentType GetExtentType() const = 0;
+
+    virtual bool operator==(const Extent& other) const = 0;
+    virtual bool operator!=(const Extent& other) const { return !(*this == other); }
 
     uint64_t num_sectors() const { return num_sectors_; }
     void set_num_sectors(uint64_t num_sectors) { num_sectors_ = num_sectors; }
@@ -58,6 +67,8 @@
     uint64_t num_sectors_;
 };
 
+std::ostream& operator<<(std::ostream& os, const Extent& extent);
+
 // This corresponds to a dm-linear target.
 class LinearExtent final : public Extent {
   public:
@@ -66,6 +77,9 @@
 
     bool AddTo(LpMetadata* metadata) const override;
     LinearExtent* AsLinearExtent() override { return this; }
+    ExtentType GetExtentType() const override { return ExtentType::kLinear; }
+
+    bool operator==(const Extent& other) const override;
 
     uint64_t physical_sector() const { return physical_sector_; }
     uint64_t end_sector() const { return physical_sector_ + num_sectors_; }
@@ -87,6 +101,9 @@
     explicit ZeroExtent(uint64_t num_sectors) : Extent(num_sectors) {}
 
     bool AddTo(LpMetadata* out) const override;
+    ExtentType GetExtentType() const override { return ExtentType::kZero; }
+
+    bool operator==(const Extent& other) const override;
 };
 
 class PartitionGroup final {
@@ -241,6 +258,14 @@
         return New(device_info, metadata_max_size, metadata_slot_count);
     }
 
+    // Verifies that the given partitions in the metadata have the same extents as the source
+    // metadata.
+    static bool VerifyExtentsAgainstSourceMetadata(const MetadataBuilder& source_metadata,
+                                                   uint32_t source_slot_number,
+                                                   const MetadataBuilder& target_metadata,
+                                                   uint32_t target_slot_number,
+                                                   const std::vector<std::string>& partitions);
+
     // Define a new partition group. By default there is one group called
     // "default", with an unrestricted size. A non-zero size will restrict the
     // total space used by all partitions in the group.
@@ -265,10 +290,10 @@
     void RemovePartition(std::string_view name);
 
     // Find a partition by name. If no partition is found, nullptr is returned.
-    Partition* FindPartition(std::string_view name);
+    Partition* FindPartition(std::string_view name) const;
 
     // Find a group by name. If no group is found, nullptr is returned.
-    PartitionGroup* FindGroup(std::string_view name);
+    PartitionGroup* FindGroup(std::string_view name) const;
 
     // Add a predetermined extent to a partition.
     bool AddLinearExtent(Partition* partition, const std::string& block_device,