diff --git a/adb/adb_utils.cpp b/adb/adb_utils.cpp
index ad77064..6960345 100644
--- a/adb/adb_utils.cpp
+++ b/adb/adb_utils.cpp
@@ -293,6 +293,9 @@
     struct passwd pwent;
     struct passwd* result;
     int pwent_max = sysconf(_SC_GETPW_R_SIZE_MAX);
+    if (pwent_max == -1) {
+        pwent_max = 16384;
+    }
     std::vector<char> buf(pwent_max);
     int rc = getpwuid_r(getuid(), &pwent, buf.data(), buf.size(), &result);
     if (rc == 0 && result) {
diff --git a/adb/client/commandline.cpp b/adb/client/commandline.cpp
index 3124852..b5bed28 100644
--- a/adb/client/commandline.cpp
+++ b/adb/client/commandline.cpp
@@ -204,8 +204,8 @@
         " sideload OTAPACKAGE      sideload the given full OTA package\n"
         " root                     restart adbd with root permissions\n"
         " unroot                   restart adbd without root permissions\n"
-        " usb                      restart adb server listening on USB\n"
-        " tcpip PORT               restart adb server listening on TCP on PORT\n"
+        " usb                      restart adbd listening on USB\n"
+        " tcpip PORT               restart adbd listening on TCP on PORT\n"
         "\n"
         "internal debugging:\n"
         " start-server             ensure that there is a server running\n"
diff --git a/base/file.cpp b/base/file.cpp
index d6fe753..3834ed4 100644
--- a/base/file.cpp
+++ b/base/file.cpp
@@ -38,7 +38,6 @@
 #endif
 #if defined(_WIN32)
 #include <windows.h>
-#define O_CLOEXEC O_NOINHERIT
 #define O_NOFOLLOW 0
 #endif
 
diff --git a/base/include/android-base/file.h b/base/include/android-base/file.h
index 908690b..8f9bf80 100644
--- a/base/include/android-base/file.h
+++ b/base/include/android-base/file.h
@@ -21,11 +21,17 @@
 #include <string>
 
 #if !defined(_WIN32) && !defined(O_BINARY)
+/** Windows needs O_BINARY, but Unix never mangles line endings. */
 #define O_BINARY 0
 #endif
 
+#if defined(_WIN32) && !defined(O_CLOEXEC)
+/** Windows has O_CLOEXEC but calls it O_NOINHERIT for some reason. */
+#define O_CLOEXEC O_NOINHERIT
+#endif
+
 #if defined(__APPLE__)
-/* Mac OS has always had a 64-bit off_t, so it doesn't have off64_t. */
+/** Mac OS has always had a 64-bit off_t, so it doesn't have off64_t. */
 typedef off_t off64_t;
 #endif
 
diff --git a/base/include/android-base/macros.h b/base/include/android-base/macros.h
index 1748665..5abf514 100644
--- a/base/include/android-base/macros.h
+++ b/base/include/android-base/macros.h
@@ -75,46 +75,6 @@
 
 #define arraysize(array) (sizeof(ArraySizeHelper(array)))
 
-// ARRAYSIZE_UNSAFE performs essentially the same calculation as arraysize,
-// but can be used on anonymous types or types defined inside
-// functions.  It's less safe than arraysize as it accepts some
-// (although not all) pointers.  Therefore, you should use arraysize
-// whenever possible.
-//
-// The expression ARRAYSIZE_UNSAFE(a) is a compile-time constant of type
-// size_t.
-//
-// ARRAYSIZE_UNSAFE catches a few type errors.  If you see a compiler error
-//
-//   "warning: division by zero in ..."
-//
-// when using ARRAYSIZE_UNSAFE, you are (wrongfully) giving it a pointer.
-// You should only use ARRAYSIZE_UNSAFE on statically allocated arrays.
-//
-// The following comments are on the implementation details, and can
-// be ignored by the users.
-//
-// ARRAYSIZE_UNSAFE(arr) works by inspecting sizeof(arr) (the # of bytes in
-// the array) and sizeof(*(arr)) (the # of bytes in one array
-// element).  If the former is divisible by the latter, perhaps arr is
-// indeed an array, in which case the division result is the # of
-// elements in the array.  Otherwise, arr cannot possibly be an array,
-// and we generate a compiler error to prevent the code from
-// compiling.
-//
-// Since the size of bool is implementation-defined, we need to cast
-// !(sizeof(a) & sizeof(*(a))) to size_t in order to ensure the final
-// result has type size_t.
-//
-// This macro is not perfect as it wrongfully accepts certain
-// pointers, namely where the pointer size is divisible by the pointee
-// size.  Since all our code has to go through a 32-bit compiler,
-// where a pointer is 4 bytes, this means all pointers to a type whose
-// size is 3 or greater than 4 will be (righteously) rejected.
-#define ARRAYSIZE_UNSAFE(a)     \
-  ((sizeof(a) / sizeof(*(a))) / \
-    static_cast<size_t>(!(sizeof(a) % sizeof(*(a)))))
-
 #define SIZEOF_MEMBER(t, f) sizeof(std::declval<t>().f)
 
 // Changing this definition will cause you a lot of pain.  A majority of
@@ -153,23 +113,23 @@
 //    case 42:
 //      ...
 //
-//  As shown in the example above, the FALLTHROUGH_INTENDED macro should be
-//  followed by a semicolon. It is designed to mimic control-flow statements
-//  like 'break;', so it can be placed in most places where 'break;' can, but
-//  only if there are no statements on the execution path between it and the
-//  next switch label.
+// As shown in the example above, the FALLTHROUGH_INTENDED macro should be
+// followed by a semicolon. It is designed to mimic control-flow statements
+// like 'break;', so it can be placed in most places where 'break;' can, but
+// only if there are no statements on the execution path between it and the
+// next switch label.
 //
-//  When compiled with clang, the FALLTHROUGH_INTENDED macro is expanded to
-//  [[clang::fallthrough]] attribute, which is analysed when performing switch
-//  labels fall-through diagnostic ('-Wimplicit-fallthrough'). See clang
-//  documentation on language extensions for details:
-//  http://clang.llvm.org/docs/LanguageExtensions.html#clang__fallthrough
+// When compiled with clang, the FALLTHROUGH_INTENDED macro is expanded to
+// [[clang::fallthrough]] attribute, which is analysed when performing switch
+// labels fall-through diagnostic ('-Wimplicit-fallthrough'). See clang
+// documentation on language extensions for details:
+// http://clang.llvm.org/docs/LanguageExtensions.html#clang__fallthrough
 //
-//  When used with unsupported compilers, the FALLTHROUGH_INTENDED macro has no
-//  effect on diagnostics.
+// When used with unsupported compilers, the FALLTHROUGH_INTENDED macro has no
+// effect on diagnostics.
 //
-//  In either case this macro has no effect on runtime behavior and performance
-//  of code.
+// In either case this macro has no effect on runtime behavior and performance
+// of code.
 #ifndef FALLTHROUGH_INTENDED
 #define FALLTHROUGH_INTENDED [[clang::fallthrough]]  // NOLINT
 #endif
diff --git a/base/include/android-base/mapped_file.h b/base/include/android-base/mapped_file.h
index 52d11ed..667ba7e 100644
--- a/base/include/android-base/mapped_file.h
+++ b/base/include/android-base/mapped_file.h
@@ -16,6 +16,11 @@
 
 #pragma once
 
+#if __APPLE__
+/* Temporary Mac build fix for off64_t. TODO: refactor into `portability.h`. */
+#include "android-base/file.h"
+#endif
+
 #include "android-base/macros.h"
 
 #include <sys/types.h>
diff --git a/fastboot/fastboot.cpp b/fastboot/fastboot.cpp
index 925cac4..81350fd 100644
--- a/fastboot/fastboot.cpp
+++ b/fastboot/fastboot.cpp
@@ -79,10 +79,6 @@
 using android::base::Trim;
 using android::base::unique_fd;
 
-#if defined(_WIN32)
-#define O_CLOEXEC O_NOINHERIT
-#endif
-
 static const char* serial = nullptr;
 
 static bool g_long_listing = false;
@@ -1316,6 +1312,9 @@
     if (!is_userspace_fastboot()) {
         reboot_to_userspace_fastboot();
     }
+    if (!is_userspace_fastboot()) {
+        die("Failed to boot into userspace; one or more components might be unbootable.");
+    }
     fb->Download("super", fd, get_file_size(fd));
 
     std::string command = "update-super:super";
diff --git a/fs_mgr/fs_mgr_dm_linear.cpp b/fs_mgr/fs_mgr_dm_linear.cpp
index 804069a..6ddd5a8 100644
--- a/fs_mgr/fs_mgr_dm_linear.cpp
+++ b/fs_mgr/fs_mgr_dm_linear.cpp
@@ -33,6 +33,7 @@
 
 #include <sstream>
 
+#include <android-base/file.h>
 #include <android-base/logging.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
@@ -50,8 +51,21 @@
 using DmTargetZero = android::dm::DmTargetZero;
 using DmTargetLinear = android::dm::DmTargetLinear;
 
-static bool CreateDmTable(const std::string& block_device, const LpMetadata& metadata,
-                          const LpMetadataPartition& partition, DmTable* table) {
+bool GetPhysicalPartitionDevicePath(const LpMetadataBlockDevice& block_device,
+                                    std::string* result) {
+    // Note: device-mapper will not accept symlinks, so we must use realpath
+    // here.
+    std::string name = GetBlockDevicePartitionName(block_device);
+    std::string path = "/dev/block/by-name/" + name;
+    if (!android::base::Realpath(path, result)) {
+        PERROR << "realpath: " << path;
+        return false;
+    }
+    return true;
+}
+
+static bool CreateDmTable(const LpMetadata& metadata, const LpMetadataPartition& partition,
+                          DmTable* table) {
     uint64_t sector = 0;
     for (size_t i = 0; i < partition.num_extents; i++) {
         const auto& extent = metadata.extents[partition.first_extent_index + i];
@@ -60,10 +74,22 @@
             case LP_TARGET_TYPE_ZERO:
                 target = std::make_unique<DmTargetZero>(sector, extent.num_sectors);
                 break;
-            case LP_TARGET_TYPE_LINEAR:
-                target = std::make_unique<DmTargetLinear>(sector, extent.num_sectors, block_device,
+            case LP_TARGET_TYPE_LINEAR: {
+                auto block_device = GetMetadataSuperBlockDevice(metadata);
+                if (!block_device) {
+                    LOG(ERROR) << "Could not identify the super block device";
+                    return false;
+                }
+
+                std::string path;
+                if (!GetPhysicalPartitionDevicePath(*block_device, &path)) {
+                    LOG(ERROR) << "Unable to complete device-mapper table, unknown block device";
+                    return false;
+                }
+                target = std::make_unique<DmTargetLinear>(sector, extent.num_sectors, path,
                                                           extent.target_data);
                 break;
+            }
             default:
                 LOG(ERROR) << "Unknown target type in metadata: " << extent.target_type;
                 return false;
@@ -79,13 +105,13 @@
     return true;
 }
 
-static bool CreateLogicalPartition(const std::string& block_device, const LpMetadata& metadata,
-                                   const LpMetadataPartition& partition, bool force_writable,
-                                   const std::chrono::milliseconds& timeout_ms, std::string* path) {
+static bool CreateLogicalPartition(const LpMetadata& metadata, const LpMetadataPartition& partition,
+                                   bool force_writable, const std::chrono::milliseconds& timeout_ms,
+                                   std::string* path) {
     DeviceMapper& dm = DeviceMapper::Instance();
 
     DmTable table;
-    if (!CreateDmTable(block_device, metadata, partition, &table)) {
+    if (!CreateDmTable(metadata, partition, &table)) {
         return false;
     }
     if (force_writable) {
@@ -122,7 +148,7 @@
             continue;
         }
         std::string path;
-        if (!CreateLogicalPartition(block_device, *metadata.get(), partition, false, {}, &path)) {
+        if (!CreateLogicalPartition(*metadata.get(), partition, false, {}, &path)) {
             LERROR << "Could not create logical partition: " << GetPartitionName(partition);
             return false;
         }
@@ -140,8 +166,8 @@
     }
     for (const auto& partition : metadata->partitions) {
         if (GetPartitionName(partition) == partition_name) {
-            return CreateLogicalPartition(block_device, *metadata.get(), partition, force_writable,
-                                          timeout_ms, path);
+            return CreateLogicalPartition(*metadata.get(), partition, force_writable, timeout_ms,
+                                          path);
         }
     }
     LERROR << "Could not find any partition with name: " << partition_name;
diff --git a/fs_mgr/fs_mgr_overlayfs.cpp b/fs_mgr/fs_mgr_overlayfs.cpp
index 64e9fb4..ad488a9 100644
--- a/fs_mgr/fs_mgr_overlayfs.cpp
+++ b/fs_mgr/fs_mgr_overlayfs.cpp
@@ -590,6 +590,7 @@
 
 // Mount kScratchMountPoint
 bool fs_mgr_overlayfs_mount_scratch(const std::string& device_path, const std::string mnt_type) {
+    if (!fs_mgr_rw_access(device_path)) return false;
     if (setfscreatecon(kOverlayfsFileContext)) {
         PERROR << "setfscreatecon " << kOverlayfsFileContext;
     }
@@ -826,6 +827,19 @@
     if (change) *change = false;
     mount_point = fs_mgr_mount_point(mount_point);
     auto ret = true;
+    // If scratch exists, but is not mounted, lets gain access to clean
+    // specific override entries.
+    if ((mount_point != nullptr) && !fs_mgr_overlayfs_already_mounted(kScratchMountPoint, false)) {
+        auto scratch_device = fs_mgr_overlayfs_scratch_device();
+        if (scratch_device.empty()) {
+            auto slot_number = fs_mgr_overlayfs_slot_number();
+            auto super_device = fs_mgr_overlayfs_super_device(slot_number);
+            const auto partition_name = android::base::Basename(kScratchMountPoint);
+            CreateLogicalPartition(super_device, slot_number, partition_name, true, 0s,
+                                   &scratch_device);
+        }
+        fs_mgr_overlayfs_mount_scratch(scratch_device, fs_mgr_overlayfs_scratch_mount_type());
+    }
     for (const auto& overlay_mount_point : kOverlayMountPoints) {
         ret &= fs_mgr_overlayfs_teardown_one(overlay_mount_point, mount_point ?: "", change);
     }
diff --git a/fs_mgr/liblp/Android.bp b/fs_mgr/liblp/Android.bp
index 4953655..5689bdf 100644
--- a/fs_mgr/liblp/Android.bp
+++ b/fs_mgr/liblp/Android.bp
@@ -25,6 +25,7 @@
     srcs: [
         "builder.cpp",
         "images.cpp",
+        "partition_opener.cpp",
         "reader.cpp",
         "utility.cpp",
         "writer.cpp",
@@ -59,6 +60,7 @@
     srcs: [
         "builder_test.cpp",
         "io_test.cpp",
+        "test_partition_opener.cpp",
         "utility_test.cpp",
     ],
 }
diff --git a/fs_mgr/liblp/builder.cpp b/fs_mgr/liblp/builder.cpp
index 2c57a35..1b8ed57 100644
--- a/fs_mgr/liblp/builder.cpp
+++ b/fs_mgr/liblp/builder.cpp
@@ -16,11 +16,7 @@
 
 #include "liblp/builder.h"
 
-#if defined(__linux__)
-#include <linux/fs.h>
-#endif
 #include <string.h>
-#include <sys/ioctl.h>
 
 #include <algorithm>
 
@@ -33,43 +29,6 @@
 namespace android {
 namespace fs_mgr {
 
-bool GetBlockDeviceInfo(const std::string& block_device, BlockDeviceInfo* device_info) {
-#if defined(__linux__)
-    android::base::unique_fd fd(open(block_device.c_str(), O_RDONLY));
-    if (fd < 0) {
-        PERROR << __PRETTY_FUNCTION__ << "open '" << block_device << "' failed";
-        return false;
-    }
-    if (!GetDescriptorSize(fd, &device_info->size)) {
-        return false;
-    }
-    if (ioctl(fd, BLKIOMIN, &device_info->alignment) < 0) {
-        PERROR << __PRETTY_FUNCTION__ << "BLKIOMIN failed";
-        return false;
-    }
-
-    int alignment_offset;
-    if (ioctl(fd, BLKALIGNOFF, &alignment_offset) < 0) {
-        PERROR << __PRETTY_FUNCTION__ << "BLKIOMIN failed";
-        return false;
-    }
-    int logical_block_size;
-    if (ioctl(fd, BLKSSZGET, &logical_block_size) < 0) {
-        PERROR << __PRETTY_FUNCTION__ << "BLKSSZGET failed";
-        return false;
-    }
-
-    device_info->alignment_offset = static_cast<uint32_t>(alignment_offset);
-    device_info->logical_block_size = static_cast<uint32_t>(logical_block_size);
-    return true;
-#else
-    (void)block_device;
-    (void)device_info;
-    LERROR << __PRETTY_FUNCTION__ << ": Not supported on this operating system.";
-    return false;
-#endif
-}
-
 void LinearExtent::AddTo(LpMetadata* out) const {
     out->extents.push_back(LpMetadataExtent{num_sectors_, LP_TARGET_TYPE_LINEAR, physical_sector_});
 }
@@ -138,9 +97,10 @@
     return sectors * LP_SECTOR_SIZE;
 }
 
-std::unique_ptr<MetadataBuilder> MetadataBuilder::New(const std::string& block_device,
+std::unique_ptr<MetadataBuilder> MetadataBuilder::New(const IPartitionOpener& opener,
+                                                      const std::string& super_partition,
                                                       uint32_t slot_number) {
-    std::unique_ptr<LpMetadata> metadata = ReadMetadata(block_device.c_str(), slot_number);
+    std::unique_ptr<LpMetadata> metadata = ReadMetadata(opener, super_partition, slot_number);
     if (!metadata) {
         return nullptr;
     }
@@ -149,12 +109,17 @@
         return nullptr;
     }
     BlockDeviceInfo device_info;
-    if (fs_mgr::GetBlockDeviceInfo(block_device, &device_info)) {
+    if (opener.GetInfo(super_partition, &device_info)) {
         builder->UpdateBlockDeviceInfo(device_info);
     }
     return builder;
 }
 
+std::unique_ptr<MetadataBuilder> MetadataBuilder::New(const std::string& super_partition,
+                                                      uint32_t slot_number) {
+    return New(PartitionOpener(), super_partition, slot_number);
+}
+
 std::unique_ptr<MetadataBuilder> MetadataBuilder::New(const BlockDeviceInfo& device_info,
                                                       uint32_t metadata_max_size,
                                                       uint32_t metadata_slot_count) {
@@ -186,6 +151,7 @@
     header_.partitions.entry_size = sizeof(LpMetadataPartition);
     header_.extents.entry_size = sizeof(LpMetadataExtent);
     header_.groups.entry_size = sizeof(LpMetadataPartitionGroup);
+    header_.block_devices.entry_size = sizeof(LpMetadataBlockDevice);
 }
 
 bool MetadataBuilder::Init(const LpMetadata& metadata) {
@@ -198,6 +164,10 @@
         }
     }
 
+    for (const auto& block_device : metadata.block_devices) {
+        block_devices_.push_back(block_device);
+    }
+
     for (const auto& partition : metadata.partitions) {
         std::string group_name = GetPartitionGroupName(metadata.groups[partition.group_index]);
         Partition* builder =
@@ -259,9 +229,7 @@
     // We reserve a geometry block (4KB) plus space for each copy of the
     // maximum size of a metadata blob. Then, we double that space since
     // we store a backup copy of everything.
-    uint64_t reserved =
-            LP_METADATA_GEOMETRY_SIZE + (uint64_t(metadata_max_size) * metadata_slot_count);
-    uint64_t total_reserved = LP_PARTITION_RESERVED_BYTES + reserved * 2;
+    uint64_t total_reserved = GetTotalMetadataSize(metadata_max_size, metadata_slot_count);
     if (device_info.size < total_reserved) {
         LERROR << "Attempting to create metadata on a block device that is too small.";
         return false;
@@ -285,12 +253,16 @@
         return false;
     }
 
-    geometry_.first_logical_sector = first_sector;
+    block_devices_.push_back(LpMetadataBlockDevice{
+            first_sector,
+            device_info.alignment,
+            device_info.alignment_offset,
+            device_info.size,
+            "super",
+    });
+
     geometry_.metadata_max_size = metadata_max_size;
     geometry_.metadata_slot_count = metadata_slot_count;
-    geometry_.alignment = device_info.alignment;
-    geometry_.alignment_offset = device_info.alignment_offset;
-    geometry_.block_device_size = device_info.size;
     geometry_.logical_block_size = device_info.logical_block_size;
 
     if (!AddGroup("default", 0)) {
@@ -408,9 +380,10 @@
     }
 
     // Add 0-length intervals for the first and last sectors. This will cause
-    // ExtentsToFreeList() to treat the space in between as available.
-    uint64_t last_sector = geometry_.block_device_size / LP_SECTOR_SIZE;
-    extents.emplace_back(geometry_.first_logical_sector, geometry_.first_logical_sector);
+    // ExtentToFreeList() to treat the space in between as available.
+    uint64_t first_sector = super_device().first_logical_sector;
+    uint64_t last_sector = super_device().size / LP_SECTOR_SIZE;
+    extents.emplace_back(first_sector, first_sector);
     extents.emplace_back(last_sector, last_sector);
 
     std::sort(extents.begin(), extents.end());
@@ -547,14 +520,18 @@
         metadata->partitions.push_back(part);
     }
 
+    metadata->block_devices = block_devices_;
+
     metadata->header.partitions.num_entries = static_cast<uint32_t>(metadata->partitions.size());
     metadata->header.extents.num_entries = static_cast<uint32_t>(metadata->extents.size());
     metadata->header.groups.num_entries = static_cast<uint32_t>(metadata->groups.size());
+    metadata->header.block_devices.num_entries =
+            static_cast<uint32_t>(metadata->block_devices.size());
     return metadata;
 }
 
 uint64_t MetadataBuilder::AllocatableSpace() const {
-    return geometry_.block_device_size - (geometry_.first_logical_sector * LP_SECTOR_SIZE);
+    return super_device().size - (super_device().first_logical_sector * LP_SECTOR_SIZE);
 }
 
 uint64_t MetadataBuilder::UsedSpace() const {
@@ -569,22 +546,22 @@
     // Note: when reading alignment info from the Kernel, we don't assume it
     // is aligned to the sector size, so we round up to the nearest sector.
     uint64_t lba = sector * LP_SECTOR_SIZE;
-    uint64_t aligned = AlignTo(lba, geometry_.alignment, geometry_.alignment_offset);
+    uint64_t aligned = AlignTo(lba, super_device().alignment, super_device().alignment_offset);
     return AlignTo(aligned, LP_SECTOR_SIZE) / LP_SECTOR_SIZE;
 }
 
 bool MetadataBuilder::GetBlockDeviceInfo(BlockDeviceInfo* info) const {
-    info->size = geometry_.block_device_size;
-    info->alignment = geometry_.alignment;
-    info->alignment_offset = geometry_.alignment_offset;
+    info->size = super_device().size;
+    info->alignment = super_device().alignment;
+    info->alignment_offset = super_device().alignment_offset;
     info->logical_block_size = geometry_.logical_block_size;
     return true;
 }
 
 bool MetadataBuilder::UpdateBlockDeviceInfo(const BlockDeviceInfo& device_info) {
-    if (device_info.size != geometry_.block_device_size) {
+    if (device_info.size != super_device().size) {
         LERROR << "Device size does not match (got " << device_info.size << ", expected "
-               << geometry_.block_device_size << ")";
+               << super_device().size << ")";
         return false;
     }
     if (device_info.logical_block_size != geometry_.logical_block_size) {
@@ -596,10 +573,10 @@
     // The kernel does not guarantee these values are present, so we only
     // replace existing values if the new values are non-zero.
     if (device_info.alignment) {
-        geometry_.alignment = device_info.alignment;
+        super_device().alignment = device_info.alignment;
     }
     if (device_info.alignment_offset) {
-        geometry_.alignment_offset = device_info.alignment_offset;
+        super_device().alignment_offset = device_info.alignment_offset;
     }
     return true;
 }
diff --git a/fs_mgr/liblp/builder_test.cpp b/fs_mgr/liblp/builder_test.cpp
index 27ad250..c02242a 100644
--- a/fs_mgr/liblp/builder_test.cpp
+++ b/fs_mgr/liblp/builder_test.cpp
@@ -132,7 +132,9 @@
     ASSERT_NE(builder, nullptr);
     unique_ptr<LpMetadata> exported = builder->Export();
     ASSERT_NE(exported, nullptr);
-    EXPECT_EQ(exported->geometry.first_logical_sector, 1536);
+    auto super_device = GetMetadataSuperBlockDevice(*exported.get());
+    ASSERT_NE(super_device, nullptr);
+    EXPECT_EQ(super_device->first_logical_sector, 1536);
 
     // Test a large alignment offset thrown in.
     device_info.alignment_offset = 753664;
@@ -140,7 +142,9 @@
     ASSERT_NE(builder, nullptr);
     exported = builder->Export();
     ASSERT_NE(exported, nullptr);
-    EXPECT_EQ(exported->geometry.first_logical_sector, 1472);
+    super_device = GetMetadataSuperBlockDevice(*exported.get());
+    ASSERT_NE(super_device, nullptr);
+    EXPECT_EQ(super_device->first_logical_sector, 1472);
 
     // Alignment offset without alignment doesn't mean anything.
     device_info.alignment = 0;
@@ -154,7 +158,9 @@
     ASSERT_NE(builder, nullptr);
     exported = builder->Export();
     ASSERT_NE(exported, nullptr);
-    EXPECT_EQ(exported->geometry.first_logical_sector, 174);
+    super_device = GetMetadataSuperBlockDevice(*exported.get());
+    ASSERT_NE(super_device, nullptr);
+    EXPECT_EQ(super_device->first_logical_sector, 174);
 
     // Test a small alignment with no alignment offset.
     device_info.alignment = 11 * 1024;
@@ -162,7 +168,9 @@
     ASSERT_NE(builder, nullptr);
     exported = builder->Export();
     ASSERT_NE(exported, nullptr);
-    EXPECT_EQ(exported->geometry.first_logical_sector, 160);
+    super_device = GetMetadataSuperBlockDevice(*exported.get());
+    ASSERT_NE(super_device, nullptr);
+    EXPECT_EQ(super_device->first_logical_sector, 160);
 }
 
 TEST(liblp, InternalPartitionAlignment) {
@@ -292,6 +300,9 @@
     unique_ptr<LpMetadata> exported = builder->Export();
     EXPECT_NE(exported, nullptr);
 
+    auto super_device = GetMetadataSuperBlockDevice(*exported.get());
+    ASSERT_NE(super_device, nullptr);
+
     // Verify geometry. Some details of this may change if we change the
     // metadata structures. So in addition to checking the exact values, we
     // also check that they are internally consistent after.
@@ -300,11 +311,11 @@
     EXPECT_EQ(geometry.struct_size, sizeof(geometry));
     EXPECT_EQ(geometry.metadata_max_size, 1024);
     EXPECT_EQ(geometry.metadata_slot_count, 2);
-    EXPECT_EQ(geometry.first_logical_sector, 32);
+    EXPECT_EQ(super_device->first_logical_sector, 32);
 
     static const size_t kMetadataSpace =
             ((kMetadataSize * kMetadataSlots) + LP_METADATA_GEOMETRY_SIZE) * 2;
-    EXPECT_GE(geometry.first_logical_sector * LP_SECTOR_SIZE, kMetadataSpace);
+    EXPECT_GE(super_device->first_logical_sector * LP_SECTOR_SIZE, kMetadataSpace);
 
     // Verify header.
     const LpMetadataHeader& header = exported->header;
@@ -413,13 +424,10 @@
                                                                fs_mgr_free_fstab);
     ASSERT_NE(fstab, nullptr);
 
-    // This should read from the "super" partition once we have a well-defined
-    // way to access it.
-    struct fstab_rec* rec = fs_mgr_get_entry_for_mount_point(fstab.get(), "/data");
-    ASSERT_NE(rec, nullptr);
+    PartitionOpener opener;
 
     BlockDeviceInfo device_info;
-    ASSERT_TRUE(GetBlockDeviceInfo(rec->blk_device, &device_info));
+    ASSERT_TRUE(opener.GetInfo(fs_mgr_get_super_partition_name(), &device_info));
 
     // Sanity check that the device doesn't give us some weird inefficient
     // alignment.
diff --git a/fs_mgr/liblp/images.cpp b/fs_mgr/liblp/images.cpp
index dfa37fe..46bdfa4 100644
--- a/fs_mgr/liblp/images.cpp
+++ b/fs_mgr/liblp/images.cpp
@@ -99,11 +99,12 @@
       block_size_(block_size),
       file_(nullptr, sparse_file_destroy),
       images_(images) {
+    uint64_t total_size = GetTotalSuperPartitionSize(metadata);
     if (block_size % LP_SECTOR_SIZE != 0) {
         LERROR << "Block size must be a multiple of the sector size, " << LP_SECTOR_SIZE;
         return;
     }
-    if (metadata.geometry.block_device_size % block_size != 0) {
+    if (total_size % block_size != 0) {
         LERROR << "Device size must be a multiple of the block size, " << block_size;
         return;
     }
@@ -120,7 +121,7 @@
         return;
     }
 
-    uint64_t num_blocks = metadata.geometry.block_device_size % block_size;
+    uint64_t num_blocks = total_size % block_size;
     if (num_blocks >= UINT_MAX) {
         // libsparse counts blocks in unsigned 32-bit integers, so we check to
         // make sure we're not going to overflow.
@@ -128,7 +129,10 @@
         return;
     }
 
-    file_.reset(sparse_file_new(block_size_, geometry_.block_device_size));
+    file_.reset(sparse_file_new(block_size_, total_size));
+    if (!file_) {
+        LERROR << "Could not allocate sparse file of size " << total_size;
+    }
 }
 
 bool SparseBuilder::Export(const char* file) {
@@ -333,14 +337,7 @@
 bool WriteToSparseFile(const char* file, const LpMetadata& metadata, uint32_t block_size,
                        const std::map<std::string, std::string>& images) {
     SparseBuilder builder(metadata, block_size, images);
-    if (!builder.IsValid()) {
-        LERROR << "Could not allocate sparse file of size " << metadata.geometry.block_device_size;
-        return false;
-    }
-    if (!builder.Build()) {
-        return false;
-    }
-    return builder.Export(file);
+    return builder.IsValid() && builder.Build() && builder.Export(file);
 }
 
 }  // namespace fs_mgr
diff --git a/fs_mgr/liblp/include/liblp/builder.h b/fs_mgr/liblp/include/liblp/builder.h
index 7e07df4..a090889 100644
--- a/fs_mgr/liblp/include/liblp/builder.h
+++ b/fs_mgr/liblp/include/liblp/builder.h
@@ -24,6 +24,7 @@
 #include <memory>
 
 #include "liblp.h"
+#include "partition_opener.h"
 
 namespace android {
 namespace fs_mgr {
@@ -34,27 +35,6 @@
 static const uint32_t kDefaultPartitionAlignment = 1024 * 1024;
 static const uint32_t kDefaultBlockSize = 4096;
 
-struct BlockDeviceInfo {
-    BlockDeviceInfo() : size(0), alignment(0), alignment_offset(0), logical_block_size(0) {}
-    BlockDeviceInfo(uint64_t size, uint32_t alignment, uint32_t alignment_offset,
-                    uint32_t logical_block_size)
-        : size(size),
-          alignment(alignment),
-          alignment_offset(alignment_offset),
-          logical_block_size(logical_block_size) {}
-    // Size of the block device, in bytes.
-    uint64_t size;
-    // Optimal target alignment, in bytes. Partition extents will be aligned to
-    // this value by default. This value must be 0 or a multiple of 512.
-    uint32_t alignment;
-    // Alignment offset to parent device (if any), in bytes. The sector at
-    // |alignment_offset| on the target device is correctly aligned on its
-    // parent device. This value must be 0 or a multiple of 512.
-    uint32_t alignment_offset;
-    // Block size, for aligning extent sizes and partition sizes.
-    uint32_t logical_block_size;
-};
-
 // Abstraction around dm-targets that can be encoded into logical partition tables.
 class Extent {
   public:
@@ -157,7 +137,12 @@
     // Import an existing table for modification. This reads metadata off the
     // given block device and imports it. It also adjusts alignment information
     // based on run-time values in the operating system.
-    static std::unique_ptr<MetadataBuilder> New(const std::string& block_device,
+    static std::unique_ptr<MetadataBuilder> New(const IPartitionOpener& opener,
+                                                const std::string& super_partition,
+                                                uint32_t slot_number);
+
+    // Same as above, but use the default PartitionOpener.
+    static std::unique_ptr<MetadataBuilder> New(const std::string& super_partition,
                                                 uint32_t slot_number);
 
     // Import an existing table for modification. If the table is not valid, for
@@ -254,10 +239,14 @@
     void ExtentsToFreeList(const std::vector<Interval>& extents,
                            std::vector<Interval>* free_regions) const;
 
+    const LpMetadataBlockDevice& super_device() const { return block_devices_[0]; }
+    LpMetadataBlockDevice& super_device() { return block_devices_[0]; }
+
     LpMetadataGeometry geometry_;
     LpMetadataHeader header_;
     std::vector<std::unique_ptr<Partition>> partitions_;
     std::vector<std::unique_ptr<PartitionGroup>> groups_;
+    std::vector<LpMetadataBlockDevice> block_devices_;
 };
 
 // Read BlockDeviceInfo for a given block device. This always returns false
diff --git a/fs_mgr/liblp/include/liblp/liblp.h b/fs_mgr/liblp/include/liblp/liblp.h
index 5f95dca..4669cea 100644
--- a/fs_mgr/liblp/include/liblp/liblp.h
+++ b/fs_mgr/liblp/include/liblp/liblp.h
@@ -24,7 +24,10 @@
 #include <memory>
 #include <string>
 
+#include <android-base/unique_fd.h>
+
 #include "metadata_format.h"
+#include "partition_opener.h"
 
 namespace android {
 namespace fs_mgr {
@@ -37,13 +40,15 @@
     std::vector<LpMetadataPartition> partitions;
     std::vector<LpMetadataExtent> extents;
     std::vector<LpMetadataPartitionGroup> groups;
+    std::vector<LpMetadataBlockDevice> block_devices;
 };
 
 // Place an initial partition table on the device. This will overwrite the
 // existing geometry, and should not be used for normal partition table
 // updates. False can be returned if the geometry is incompatible with the
 // block device or an I/O error occurs.
-bool FlashPartitionTable(const std::string& block_device, const LpMetadata& metadata);
+bool FlashPartitionTable(const IPartitionOpener& opener, const std::string& super_partition,
+                         const LpMetadata& metadata);
 
 // Update the partition table for a given metadata slot number. False is
 // returned if an error occurs, which can include:
@@ -51,12 +56,19 @@
 //  - I/O error.
 //  - Corrupt or missing metadata geometry on disk.
 //  - Incompatible geometry.
-bool UpdatePartitionTable(const std::string& block_device, const LpMetadata& metadata,
-                          uint32_t slot_number);
+bool UpdatePartitionTable(const IPartitionOpener& opener, const std::string& super_partition,
+                          const LpMetadata& metadata, uint32_t slot_number);
 
 // Read logical partition metadata from its predetermined location on a block
 // device. If readback fails, we also attempt to load from a backup copy.
-std::unique_ptr<LpMetadata> ReadMetadata(const char* block_device, uint32_t slot_number);
+std::unique_ptr<LpMetadata> ReadMetadata(const IPartitionOpener& opener,
+                                         const std::string& super_partition, uint32_t slot_number);
+
+// Helper functions that use the default PartitionOpener.
+bool FlashPartitionTable(const std::string& super_partition, const LpMetadata& metadata);
+bool UpdatePartitionTable(const std::string& super_partition, const LpMetadata& metadata,
+                          uint32_t slot_number);
+std::unique_ptr<LpMetadata> ReadMetadata(const std::string& super_partition, uint32_t slot_number);
 
 // Read/Write logical partition metadata to an image file, for diagnostics or
 // flashing.
@@ -69,6 +81,14 @@
 // Helper to extract safe C++ strings from partition info.
 std::string GetPartitionName(const LpMetadataPartition& partition);
 std::string GetPartitionGroupName(const LpMetadataPartitionGroup& group);
+std::string GetBlockDevicePartitionName(const LpMetadataBlockDevice& block_device);
+
+// Return the block device that houses the super partition metadata; returns
+// null on failure.
+const LpMetadataBlockDevice* GetMetadataSuperBlockDevice(const LpMetadata& metadata);
+
+// Return the total size of all partitions comprising the super partition.
+uint64_t GetTotalSuperPartitionSize(const LpMetadata& metadata);
 
 // Helper to return a slot number for a slot suffix.
 uint32_t SlotNumberForSlotSuffix(const std::string& suffix);
diff --git a/fs_mgr/liblp/include/liblp/metadata_format.h b/fs_mgr/liblp/include/liblp/metadata_format.h
index 89b219c..8a309be 100644
--- a/fs_mgr/liblp/include/liblp/metadata_format.h
+++ b/fs_mgr/liblp/include/liblp/metadata_format.h
@@ -38,7 +38,7 @@
 #define LP_METADATA_HEADER_MAGIC 0x414C5030
 
 /* Current metadata version. */
-#define LP_METADATA_MAJOR_VERSION 6
+#define LP_METADATA_MAJOR_VERSION 7
 #define LP_METADATA_MINOR_VERSION 0
 
 /* Attributes for the LpMetadataPartition::attributes field.
@@ -103,42 +103,10 @@
      */
     uint32_t metadata_slot_count;
 
-    /* 48: First usable sector for allocating logical partitions. this will be
-     * the first sector after the initial geometry blocks, followed by the
-     * space consumed by metadata_max_size*metadata_slot_count*2.
-     */
-    uint64_t first_logical_sector;
-
-    /* 64: Alignment for defining partitions or partition extents. For example,
-     * an alignment of 1MiB will require that all partitions have a size evenly
-     * divisible by 1MiB, and that the smallest unit the partition can grow by
-     * is 1MiB.
-     *
-     * Alignment is normally determined at runtime when growing or adding
-     * partitions. If for some reason the alignment cannot be determined, then
-     * this predefined alignment in the geometry is used instead. By default
-     * it is set to 1MiB.
-     */
-    uint32_t alignment;
-
-    /* 68: Alignment offset for "stacked" devices. For example, if the "super"
-     * partition itself is not aligned within the parent block device's
-     * partition table, then we adjust for this in deciding where to place
-     * |first_logical_sector|.
-     *
-     * Similar to |alignment|, this will be derived from the operating system.
-     * If it cannot be determined, it is assumed to be 0.
-     */
-    uint32_t alignment_offset;
-
-    /* 72: Block device size, as specified when the metadata was created. This
-     * can be used to verify the geometry against a target device.
-     */
-    uint64_t block_device_size;
-
-    /* 76: Logical block size of the super partition block device. This is the
-     * minimal alignment for partition and extent sizes, and it must be a
-     * multiple of LP_SECTOR_SIZE.
+    /* 48: Logical block size. This is the minimal alignment for partition and
+     * extent sizes, and it must be a multiple of LP_SECTOR_SIZE. Note that
+     * this must be equal across all LUNs that comprise the super partition,
+     * and thus this field is stored in the geometry, not per-device.
      */
     uint32_t logical_block_size;
 } __attribute__((packed)) LpMetadataGeometry;
@@ -217,6 +185,8 @@
     LpMetadataTableDescriptor extents;
     /* 104: Updateable group descriptor. */
     LpMetadataTableDescriptor groups;
+    /* 116: Block device table. */
+    LpMetadataTableDescriptor block_devices;
 } __attribute__((packed)) LpMetadataHeader;
 
 /* This struct defines a logical partition entry, similar to what would be
@@ -285,6 +255,47 @@
     uint64_t maximum_size;
 } LpMetadataPartitionGroup;
 
+/* This struct defines an entry in the block_devices table. There must be
+ * exactly one device, corresponding to the super partition.
+ */
+typedef struct LpMetadataBlockDevice {
+    /* 0: First usable sector for allocating logical partitions. this will be
+     * the first sector after the initial geometry blocks, followed by the
+     * space consumed by metadata_max_size*metadata_slot_count*2.
+     */
+    uint64_t first_logical_sector;
+
+    /* 8: Alignment for defining partitions or partition extents. For example,
+     * an alignment of 1MiB will require that all partitions have a size evenly
+     * divisible by 1MiB, and that the smallest unit the partition can grow by
+     * is 1MiB.
+     *
+     * Alignment is normally determined at runtime when growing or adding
+     * partitions. If for some reason the alignment cannot be determined, then
+     * this predefined alignment in the geometry is used instead. By default
+     * it is set to 1MiB.
+     */
+    uint32_t alignment;
+
+    /* 12: Alignment offset for "stacked" devices. For example, if the "super"
+     * partition itself is not aligned within the parent block device's
+     * partition table, then we adjust for this in deciding where to place
+     * |first_logical_sector|.
+     *
+     * Similar to |alignment|, this will be derived from the operating system.
+     * If it cannot be determined, it is assumed to be 0.
+     */
+    uint32_t alignment_offset;
+
+    /* 16: Block device size, as specified when the metadata was created. This
+     * can be used to verify the geometry against a target device.
+     */
+    uint64_t size;
+
+    /* 24: Partition name in the GPT. Any unused characters must be 0. */
+    char partition_name[36];
+} LpMetadataBlockDevice;
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
diff --git a/fs_mgr/liblp/include/liblp/partition_opener.h b/fs_mgr/liblp/include/liblp/partition_opener.h
new file mode 100644
index 0000000..fe61b9c
--- /dev/null
+++ b/fs_mgr/liblp/include/liblp/partition_opener.h
@@ -0,0 +1,73 @@
+//
+// Copyright (C) 2018 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 <stdint.h>
+
+#include <string>
+
+#include <android-base/unique_fd.h>
+
+namespace android {
+namespace fs_mgr {
+
+struct BlockDeviceInfo {
+    BlockDeviceInfo() : size(0), alignment(0), alignment_offset(0), logical_block_size(0) {}
+    BlockDeviceInfo(uint64_t size, uint32_t alignment, uint32_t alignment_offset,
+                    uint32_t logical_block_size)
+        : size(size),
+          alignment(alignment),
+          alignment_offset(alignment_offset),
+          logical_block_size(logical_block_size) {}
+    // Size of the block device, in bytes.
+    uint64_t size;
+    // Optimal target alignment, in bytes. Partition extents will be aligned to
+    // this value by default. This value must be 0 or a multiple of 512.
+    uint32_t alignment;
+    // Alignment offset to parent device (if any), in bytes. The sector at
+    // |alignment_offset| on the target device is correctly aligned on its
+    // parent device. This value must be 0 or a multiple of 512.
+    uint32_t alignment_offset;
+    // Block size, for aligning extent sizes and partition sizes.
+    uint32_t logical_block_size;
+};
+
+// Test-friendly interface for interacting with partitions.
+class IPartitionOpener {
+  public:
+    virtual ~IPartitionOpener() = default;
+
+    // Open the given named physical partition with the provided open() flags.
+    // The name can be an absolute path if the full path is already known.
+    virtual android::base::unique_fd Open(const std::string& partition_name, int flags) const = 0;
+
+    // Return block device information about the given named physical partition.
+    // The name can be an absolute path if the full path is already known.
+    virtual bool GetInfo(const std::string& partition_name, BlockDeviceInfo* info) const = 0;
+};
+
+// Helper class to implement IPartitionOpener. If |partition_name| is not an
+// absolute path, /dev/block/by-name/ will be prepended.
+class PartitionOpener : public IPartitionOpener {
+  public:
+    virtual android::base::unique_fd Open(const std::string& partition_name,
+                                          int flags) const override;
+    virtual bool GetInfo(const std::string& partition_name, BlockDeviceInfo* info) const override;
+};
+
+}  // namespace fs_mgr
+}  // namespace android
diff --git a/fs_mgr/liblp/io_test.cpp b/fs_mgr/liblp/io_test.cpp
index 2aa41f3..9c675fe 100644
--- a/fs_mgr/liblp/io_test.cpp
+++ b/fs_mgr/liblp/io_test.cpp
@@ -26,6 +26,7 @@
 
 #include "images.h"
 #include "reader.h"
+#include "test_partition_opener.h"
 #include "utility.h"
 #include "writer.h"
 
@@ -101,7 +102,9 @@
     if (!exported) {
         return {};
     }
-    if (!FlashPartitionTable(fd, *exported.get())) {
+
+    TestPartitionOpener opener({{"super", fd}});
+    if (!FlashPartitionTable(opener, "super", *exported.get())) {
         return {};
     }
     return fd;
@@ -116,8 +119,10 @@
     ASSERT_TRUE(GetDescriptorSize(fd, &size));
     ASSERT_EQ(size, kDiskSize);
 
+    TestPartitionOpener opener({{"super", fd}});
+
     // Verify that we can't read unwritten metadata.
-    ASSERT_EQ(ReadMetadata(fd, 1), nullptr);
+    ASSERT_EQ(ReadMetadata(opener, "super", 1), nullptr);
 }
 
 // Flashing metadata should not work if the metadata was created for a larger
@@ -133,7 +138,9 @@
     unique_fd fd = CreateFakeDisk();
     ASSERT_GE(fd, 0);
 
-    EXPECT_FALSE(FlashPartitionTable(fd, *exported.get()));
+    TestPartitionOpener opener({{"super", fd}});
+
+    EXPECT_FALSE(FlashPartitionTable(opener, "super", *exported.get()));
 }
 
 // Test the basics of flashing a partition and reading it back.
@@ -145,22 +152,23 @@
     unique_fd fd = CreateFakeDisk();
     ASSERT_GE(fd, 0);
 
+    TestPartitionOpener opener({{"super", fd}});
+
     // Export and flash.
     unique_ptr<LpMetadata> exported = builder->Export();
     ASSERT_NE(exported, nullptr);
-    ASSERT_TRUE(FlashPartitionTable(fd, *exported.get()));
+    ASSERT_TRUE(FlashPartitionTable(opener, "super", *exported.get()));
 
     // Read back. Note that some fields are only filled in during
     // serialization, so exported and imported will not be identical. For
     // example, table sizes and checksums are computed in WritePartitionTable.
     // Therefore we check on a field-by-field basis.
-    unique_ptr<LpMetadata> imported = ReadMetadata(fd, 0);
+    unique_ptr<LpMetadata> imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
 
     // Check geometry and header.
     EXPECT_EQ(exported->geometry.metadata_max_size, imported->geometry.metadata_max_size);
     EXPECT_EQ(exported->geometry.metadata_slot_count, imported->geometry.metadata_slot_count);
-    EXPECT_EQ(exported->geometry.first_logical_sector, imported->geometry.first_logical_sector);
     EXPECT_EQ(exported->header.major_version, imported->header.major_version);
     EXPECT_EQ(exported->header.minor_version, imported->header.minor_version);
     EXPECT_EQ(exported->header.header_size, imported->header.header_size);
@@ -178,6 +186,11 @@
     EXPECT_EQ(exported->extents[0].num_sectors, imported->extents[0].num_sectors);
     EXPECT_EQ(exported->extents[0].target_type, imported->extents[0].target_type);
     EXPECT_EQ(exported->extents[0].target_data, imported->extents[0].target_data);
+
+    // Check block devices table.
+    ASSERT_EQ(exported->block_devices.size(), imported->block_devices.size());
+    EXPECT_EQ(exported->block_devices[0].first_logical_sector,
+              imported->block_devices[0].first_logical_sector);
 }
 
 // Test that we can update metadata slots without disturbing others.
@@ -185,35 +198,40 @@
     unique_fd fd = CreateFlashedDisk();
     ASSERT_GE(fd, 0);
 
-    unique_ptr<LpMetadata> imported = ReadMetadata(fd, 0);
+    TestPartitionOpener opener({{"super", fd}});
+
+    unique_ptr<LpMetadata> imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
     ASSERT_EQ(imported->partitions.size(), 1);
     EXPECT_EQ(GetPartitionName(imported->partitions[0]), "system");
 
     // Change the name before writing to the next slot.
     strncpy(imported->partitions[0].name, "vendor", sizeof(imported->partitions[0].name));
-    ASSERT_TRUE(UpdatePartitionTable(fd, *imported.get(), 1));
+    ASSERT_TRUE(UpdatePartitionTable(opener, "super", *imported.get(), 1));
 
     // Read back the original slot, make sure it hasn't changed.
-    imported = ReadMetadata(fd, 0);
+    imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
     ASSERT_EQ(imported->partitions.size(), 1);
     EXPECT_EQ(GetPartitionName(imported->partitions[0]), "system");
 
     // Now read back the new slot, and verify that it has a different name.
-    imported = ReadMetadata(fd, 1);
+    imported = ReadMetadata(opener, "super", 1);
     ASSERT_NE(imported, nullptr);
     ASSERT_EQ(imported->partitions.size(), 1);
     EXPECT_EQ(GetPartitionName(imported->partitions[0]), "vendor");
 
-    uint64_t last_sector = imported->geometry.block_device_size / LP_SECTOR_SIZE;
+    auto super_device = GetMetadataSuperBlockDevice(*imported.get());
+    ASSERT_NE(super_device, nullptr);
+
+    uint64_t last_sector = super_device->size / LP_SECTOR_SIZE;
 
     // Verify that we didn't overwrite anything in the logical paritition area.
     // We expect the disk to be filled with 0xcc on creation so we can read
     // this back and compare it.
     char expected[LP_SECTOR_SIZE];
     memset(expected, 0xcc, sizeof(expected));
-    for (uint64_t i = imported->geometry.first_logical_sector; i < last_sector; i++) {
+    for (uint64_t i = super_device->first_logical_sector; i < last_sector; i++) {
         char buffer[LP_SECTOR_SIZE];
         ASSERT_GE(lseek(fd, i * LP_SECTOR_SIZE, SEEK_SET), 0);
         ASSERT_TRUE(android::base::ReadFully(fd, buffer, sizeof(buffer)));
@@ -225,15 +243,17 @@
     unique_fd fd = CreateFlashedDisk();
     ASSERT_GE(fd, 0);
 
+    TestPartitionOpener opener({{"super", fd}});
+
     // Make sure all slots are filled.
-    unique_ptr<LpMetadata> metadata = ReadMetadata(fd, 0);
+    unique_ptr<LpMetadata> metadata = ReadMetadata(opener, "super", 0);
     ASSERT_NE(metadata, nullptr);
     for (uint32_t i = 1; i < kMetadataSlots; i++) {
-        ASSERT_TRUE(UpdatePartitionTable(fd, *metadata.get(), i));
+        ASSERT_TRUE(UpdatePartitionTable(opener, "super", *metadata.get(), i));
     }
 
     // Verify that we can't read unavailable slots.
-    EXPECT_EQ(ReadMetadata(fd, kMetadataSlots), nullptr);
+    EXPECT_EQ(ReadMetadata(opener, "super", kMetadataSlots), nullptr);
 }
 
 // Test that updating a metadata slot does not allow it to be computed based
@@ -242,24 +262,27 @@
     unique_fd fd = CreateFlashedDisk();
     ASSERT_GE(fd, 0);
 
-    unique_ptr<LpMetadata> imported = ReadMetadata(fd, 0);
+    TestPartitionOpener opener({{"super", fd}});
+
+    unique_ptr<LpMetadata> imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
-    ASSERT_TRUE(UpdatePartitionTable(fd, *imported.get(), 1));
+    ASSERT_TRUE(UpdatePartitionTable(opener, "super", *imported.get(), 1));
 
     imported->geometry.metadata_max_size += LP_SECTOR_SIZE;
-    ASSERT_FALSE(UpdatePartitionTable(fd, *imported.get(), 1));
+    ASSERT_FALSE(UpdatePartitionTable(opener, "super", *imported.get(), 1));
 
-    imported = ReadMetadata(fd, 0);
+    imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
     imported->geometry.metadata_slot_count++;
-    ASSERT_FALSE(UpdatePartitionTable(fd, *imported.get(), 1));
+    ASSERT_FALSE(UpdatePartitionTable(opener, "super", *imported.get(), 1));
 
-    imported = ReadMetadata(fd, 0);
+    imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
-    imported->geometry.first_logical_sector++;
-    ASSERT_FALSE(UpdatePartitionTable(fd, *imported.get(), 1));
+    ASSERT_EQ(imported->block_devices.size(), 1);
+    imported->block_devices[0].first_logical_sector++;
+    ASSERT_FALSE(UpdatePartitionTable(opener, "super", *imported.get(), 1));
 
-    imported = ReadMetadata(fd, 0);
+    imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
 }
 
@@ -268,6 +291,8 @@
     unique_fd fd = CreateFlashedDisk();
     ASSERT_GE(fd, 0);
 
+    TestPartitionOpener opener({{"super", fd}});
+
     LpMetadataGeometry geometry;
     ASSERT_GE(lseek(fd, 0, SEEK_SET), 0);
     ASSERT_TRUE(android::base::ReadFully(fd, &geometry, sizeof(geometry)));
@@ -276,7 +301,7 @@
     bad_geometry.metadata_slot_count++;
     ASSERT_TRUE(android::base::WriteFully(fd, &bad_geometry, sizeof(bad_geometry)));
 
-    unique_ptr<LpMetadata> metadata = ReadMetadata(fd, 0);
+    unique_ptr<LpMetadata> metadata = ReadMetadata(opener, "super", 0);
     ASSERT_NE(metadata, nullptr);
     EXPECT_EQ(metadata->geometry.metadata_slot_count, 2);
 }
@@ -285,25 +310,29 @@
     unique_fd fd = CreateFlashedDisk();
     ASSERT_GE(fd, 0);
 
+    TestPartitionOpener opener({{"super", fd}});
+
     char corruption[LP_METADATA_GEOMETRY_SIZE];
     memset(corruption, 0xff, sizeof(corruption));
 
     // Corrupt the primary geometry.
     ASSERT_GE(lseek(fd, GetPrimaryGeometryOffset(), SEEK_SET), 0);
     ASSERT_TRUE(android::base::WriteFully(fd, corruption, sizeof(corruption)));
-    EXPECT_NE(ReadMetadata(fd, 0), nullptr);
+    EXPECT_NE(ReadMetadata(opener, "super", 0), nullptr);
 
     // Corrupt the backup geometry.
     ASSERT_GE(lseek(fd, GetBackupGeometryOffset(), SEEK_SET), 0);
     ASSERT_TRUE(android::base::WriteFully(fd, corruption, sizeof(corruption)));
-    EXPECT_EQ(ReadMetadata(fd, 0), nullptr);
+    EXPECT_EQ(ReadMetadata(opener, "super", 0), nullptr);
 }
 
 TEST(liblp, ReadBackupMetadata) {
     unique_fd fd = CreateFlashedDisk();
     ASSERT_GE(fd, 0);
 
-    unique_ptr<LpMetadata> metadata = ReadMetadata(fd, 0);
+    TestPartitionOpener opener({{"super", fd}});
+
+    unique_ptr<LpMetadata> metadata = ReadMetadata(opener, "super", 0);
 
     char corruption[kMetadataSize];
     memset(corruption, 0xff, sizeof(corruption));
@@ -312,14 +341,14 @@
 
     ASSERT_GE(lseek(fd, offset, SEEK_SET), 0);
     ASSERT_TRUE(android::base::WriteFully(fd, corruption, sizeof(corruption)));
-    EXPECT_NE(ReadMetadata(fd, 0), nullptr);
+    EXPECT_NE(ReadMetadata(opener, "super", 0), nullptr);
 
     offset = GetBackupMetadataOffset(metadata->geometry, 0);
 
     // Corrupt the backup metadata.
     ASSERT_GE(lseek(fd, offset, SEEK_SET), 0);
     ASSERT_TRUE(android::base::WriteFully(fd, corruption, sizeof(corruption)));
-    EXPECT_EQ(ReadMetadata(fd, 0), nullptr);
+    EXPECT_EQ(ReadMetadata(opener, "super", 0), nullptr);
 }
 
 // Test that we don't attempt to write metadata if it would overflow its
@@ -329,9 +358,11 @@
     ASSERT_NE(builder, nullptr);
 
     // Compute the maximum number of partitions we can fit in 512 bytes of
-    // metadata. By default there is the header, and one partition group.
-    static const size_t kMaxPartitionTableSize =
-            kMetadataSize - sizeof(LpMetadataHeader) - sizeof(LpMetadataPartitionGroup);
+    // metadata. By default there is the header, one partition group, and a
+    // block device entry.
+    static const size_t kMaxPartitionTableSize = kMetadataSize - sizeof(LpMetadataHeader) -
+                                                 sizeof(LpMetadataPartitionGroup) -
+                                                 sizeof(LpMetadataBlockDevice);
     size_t max_partitions = kMaxPartitionTableSize / sizeof(LpMetadataPartition);
 
     // Add this number of partitions.
@@ -347,8 +378,10 @@
     unique_fd fd = CreateFakeDisk();
     ASSERT_GE(fd, 0);
 
+    TestPartitionOpener opener({{"super", fd}});
+
     // Check that we are able to write our table.
-    ASSERT_TRUE(FlashPartitionTable(fd, *exported.get()));
+    ASSERT_TRUE(FlashPartitionTable(opener, "super", *exported.get()));
 
     // Check that adding one more partition overflows the metadata allotment.
     partition = builder->AddPartition("final", LP_PARTITION_ATTR_NONE);
@@ -358,14 +391,17 @@
     ASSERT_NE(exported, nullptr);
 
     // The new table should be too large to be written.
-    ASSERT_FALSE(UpdatePartitionTable(fd, *exported.get(), 1));
+    ASSERT_FALSE(UpdatePartitionTable(opener, "super", *exported.get(), 1));
+
+    auto super_device = GetMetadataSuperBlockDevice(*exported.get());
+    ASSERT_NE(super_device, nullptr);
 
     // Check that the first and last logical sectors weren't touched when we
     // wrote this almost-full metadata.
     char expected[LP_SECTOR_SIZE];
     memset(expected, 0xcc, sizeof(expected));
     char buffer[LP_SECTOR_SIZE];
-    ASSERT_GE(lseek(fd, exported->geometry.first_logical_sector * LP_SECTOR_SIZE, SEEK_SET), 0);
+    ASSERT_GE(lseek(fd, super_device->first_logical_sector * LP_SECTOR_SIZE, SEEK_SET), 0);
     ASSERT_TRUE(android::base::ReadFully(fd, buffer, sizeof(buffer)));
     EXPECT_EQ(memcmp(expected, buffer, LP_SECTOR_SIZE), 0);
 }
@@ -451,23 +487,25 @@
     unique_fd fd = CreateFlashedDisk();
     ASSERT_GE(fd, 0);
 
+    TestPartitionOpener opener({{"super", fd}});
+
     BadWriter writer;
 
     // Read and write it back.
     writer.FailOnWrite(1);
-    unique_ptr<LpMetadata> imported = ReadMetadata(fd, 0);
+    unique_ptr<LpMetadata> imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
-    ASSERT_FALSE(UpdatePartitionTable(fd, *imported.get(), 0, writer));
+    ASSERT_FALSE(UpdatePartitionTable(opener, "super", *imported.get(), 0, writer));
 
     // We should still be able to read the backup copy.
-    imported = ReadMetadata(fd, 0);
+    imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
 
     // Flash again, this time fail the backup copy. We should still be able
     // to read the primary.
     writer.FailOnWrite(3);
-    ASSERT_FALSE(UpdatePartitionTable(fd, *imported.get(), 0, writer));
-    imported = ReadMetadata(fd, 0);
+    ASSERT_FALSE(UpdatePartitionTable(opener, "super", *imported.get(), 0, writer));
+    imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
 }
 
@@ -477,23 +515,25 @@
     unique_fd fd = CreateFlashedDisk();
     ASSERT_GE(fd, 0);
 
+    TestPartitionOpener opener({{"super", fd}});
+
     BadWriter writer;
 
     // Read and write it back.
     writer.FailOnWrite(2);
-    unique_ptr<LpMetadata> imported = ReadMetadata(fd, 0);
+    unique_ptr<LpMetadata> imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
-    ASSERT_FALSE(UpdatePartitionTable(fd, *imported.get(), 0, writer));
+    ASSERT_FALSE(UpdatePartitionTable(opener, "super", *imported.get(), 0, writer));
 
     // We should still be able to read the primary copy.
-    imported = ReadMetadata(fd, 0);
+    imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
 
     // Flash again, this time fail the primary copy. We should still be able
     // to read the primary.
     writer.FailOnWrite(2);
-    ASSERT_FALSE(UpdatePartitionTable(fd, *imported.get(), 0, writer));
-    imported = ReadMetadata(fd, 0);
+    ASSERT_FALSE(UpdatePartitionTable(opener, "super", *imported.get(), 0, writer));
+    imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
 }
 
@@ -504,20 +544,22 @@
     unique_fd fd = CreateFlashedDisk();
     ASSERT_GE(fd, 0);
 
+    TestPartitionOpener opener({{"super", fd}});
+
     BadWriter writer;
 
     // Change the name of the existing partition.
-    unique_ptr<LpMetadata> new_table = ReadMetadata(fd, 0);
+    unique_ptr<LpMetadata> new_table = ReadMetadata(opener, "super", 0);
     ASSERT_NE(new_table, nullptr);
     ASSERT_GE(new_table->partitions.size(), 1);
     new_table->partitions[0].name[0]++;
 
     // Flash it, but fail to write the backup copy.
     writer.FailAfterWrite(2);
-    ASSERT_FALSE(UpdatePartitionTable(fd, *new_table.get(), 0, writer));
+    ASSERT_FALSE(UpdatePartitionTable(opener, "super", *new_table.get(), 0, writer));
 
     // When we read back, we should get the updated primary copy.
-    unique_ptr<LpMetadata> imported = ReadMetadata(fd, 0);
+    unique_ptr<LpMetadata> imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
     ASSERT_GE(new_table->partitions.size(), 1);
     ASSERT_EQ(GetPartitionName(new_table->partitions[0]), GetPartitionName(imported->partitions[0]));
@@ -526,9 +568,9 @@
     // Note that the sync step should have used the primary to sync, not
     // the backup.
     writer.Reset();
-    ASSERT_TRUE(UpdatePartitionTable(fd, *new_table.get(), 0, writer));
+    ASSERT_TRUE(UpdatePartitionTable(opener, "super", *new_table.get(), 0, writer));
 
-    imported = ReadMetadata(fd, 0);
+    imported = ReadMetadata(opener, "super", 0);
     ASSERT_NE(imported, nullptr);
     ASSERT_GE(new_table->partitions.size(), 1);
     ASSERT_EQ(GetPartitionName(new_table->partitions[0]), GetPartitionName(imported->partitions[0]));
diff --git a/fs_mgr/liblp/partition_opener.cpp b/fs_mgr/liblp/partition_opener.cpp
new file mode 100644
index 0000000..7381eed
--- /dev/null
+++ b/fs_mgr/liblp/partition_opener.cpp
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2018 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 "liblp/partition_opener.h"
+
+#if defined(__linux__)
+#include <linux/fs.h>
+#endif
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "utility.h"
+
+namespace android {
+namespace fs_mgr {
+
+using android::base::unique_fd;
+
+namespace {
+
+std::string GetPartitionAbsolutePath(const std::string& path) {
+    if (path[0] == '/') {
+        return path;
+    }
+    return "/dev/block/by-name/" + path;
+}
+
+bool GetBlockDeviceInfo(const std::string& block_device, BlockDeviceInfo* device_info) {
+#if defined(__linux__)
+    unique_fd fd(open(block_device.c_str(), O_RDONLY));
+    if (fd < 0) {
+        PERROR << __PRETTY_FUNCTION__ << "open '" << block_device << "' failed";
+        return false;
+    }
+    if (!GetDescriptorSize(fd, &device_info->size)) {
+        return false;
+    }
+    if (ioctl(fd, BLKIOMIN, &device_info->alignment) < 0) {
+        PERROR << __PRETTY_FUNCTION__ << "BLKIOMIN failed";
+        return false;
+    }
+
+    int alignment_offset;
+    if (ioctl(fd, BLKALIGNOFF, &alignment_offset) < 0) {
+        PERROR << __PRETTY_FUNCTION__ << "BLKIOMIN failed";
+        return false;
+    }
+    int logical_block_size;
+    if (ioctl(fd, BLKSSZGET, &logical_block_size) < 0) {
+        PERROR << __PRETTY_FUNCTION__ << "BLKSSZGET failed";
+        return false;
+    }
+
+    device_info->alignment_offset = static_cast<uint32_t>(alignment_offset);
+    device_info->logical_block_size = static_cast<uint32_t>(logical_block_size);
+    return true;
+#else
+    (void)block_device;
+    (void)device_info;
+    LERROR << __PRETTY_FUNCTION__ << ": Not supported on this operating system.";
+    return false;
+#endif
+}
+
+}  // namespace
+
+unique_fd PartitionOpener::Open(const std::string& partition_name, int flags) const {
+    std::string path = GetPartitionAbsolutePath(partition_name);
+    return unique_fd{open(path.c_str(), flags)};
+}
+
+bool PartitionOpener::GetInfo(const std::string& partition_name, BlockDeviceInfo* info) const {
+    std::string path = GetPartitionAbsolutePath(partition_name);
+    return GetBlockDeviceInfo(path, info);
+}
+
+}  // namespace fs_mgr
+}  // namespace android
diff --git a/fs_mgr/liblp/reader.cpp b/fs_mgr/liblp/reader.cpp
index 43d8076..070573c 100644
--- a/fs_mgr/liblp/reader.cpp
+++ b/fs_mgr/liblp/reader.cpp
@@ -108,15 +108,6 @@
         LERROR << "Metadata max size is not sector-aligned.";
         return false;
     }
-
-    // Check that the metadata area and logical partition areas don't overlap.
-    int64_t end_of_metadata =
-            GetPrimaryMetadataOffset(*geometry, geometry->metadata_slot_count - 1) +
-            geometry->metadata_max_size;
-    if (uint64_t(end_of_metadata) > geometry->first_logical_sector * LP_SECTOR_SIZE) {
-        LERROR << "Logical partition metadata overlaps with logical partition contents.";
-        return false;
-    }
     return true;
 }
 
@@ -195,7 +186,8 @@
     }
     if (!ValidateTableBounds(header, header.partitions) ||
         !ValidateTableBounds(header, header.extents) ||
-        !ValidateTableBounds(header, header.groups)) {
+        !ValidateTableBounds(header, header.groups) ||
+        !ValidateTableBounds(header, header.block_devices)) {
         LERROR << "Logical partition metadata has invalid table bounds.";
         return false;
     }
@@ -294,6 +286,28 @@
         metadata->groups.push_back(group);
     }
 
+    cursor = buffer.get() + header.block_devices.offset;
+    for (size_t i = 0; i < header.block_devices.num_entries; i++) {
+        LpMetadataBlockDevice device = {};
+        memcpy(&device, cursor, sizeof(device));
+        cursor += header.block_devices.entry_size;
+
+        metadata->block_devices.push_back(device);
+    }
+
+    const LpMetadataBlockDevice* super_device = GetMetadataSuperBlockDevice(*metadata.get());
+    if (!super_device) {
+        LERROR << "Metadata does not specify a super device.";
+        return nullptr;
+    }
+
+    // Check that the metadata area and logical partition areas don't overlap.
+    uint64_t metadata_region =
+            GetTotalMetadataSize(geometry.metadata_max_size, geometry.metadata_slot_count);
+    if (metadata_region > super_device->first_logical_sector * LP_SECTOR_SIZE) {
+        LERROR << "Logical partition metadata overlaps with logical partition contents.";
+        return nullptr;
+    }
     return metadata;
 }
 
@@ -328,7 +342,14 @@
     return ParseMetadata(geometry, fd);
 }
 
-std::unique_ptr<LpMetadata> ReadMetadata(int fd, uint32_t slot_number) {
+std::unique_ptr<LpMetadata> ReadMetadata(const IPartitionOpener& opener,
+                                         const std::string& super_partition, uint32_t slot_number) {
+    android::base::unique_fd fd = opener.Open(super_partition, O_RDONLY);
+    if (fd < 0) {
+        PERROR << __PRETTY_FUNCTION__ << " open failed: " << super_partition;
+        return nullptr;
+    }
+
     LpMetadataGeometry geometry;
     if (!ReadLogicalPartitionGeometry(fd, &geometry)) {
         return nullptr;
@@ -347,13 +368,8 @@
     return ReadBackupMetadata(fd, geometry, slot_number);
 }
 
-std::unique_ptr<LpMetadata> ReadMetadata(const char* block_device, uint32_t slot_number) {
-    android::base::unique_fd fd(open(block_device, O_RDONLY));
-    if (fd < 0) {
-        PERROR << __PRETTY_FUNCTION__ << " open failed: " << block_device;
-        return nullptr;
-    }
-    return ReadMetadata(fd, slot_number);
+std::unique_ptr<LpMetadata> ReadMetadata(const std::string& super_partition, uint32_t slot_number) {
+    return ReadMetadata(PartitionOpener(), super_partition, slot_number);
 }
 
 static std::string NameFromFixedArray(const char* name, size_t buffer_size) {
@@ -374,5 +390,9 @@
     return NameFromFixedArray(group.name, sizeof(group.name));
 }
 
+std::string GetBlockDevicePartitionName(const LpMetadataBlockDevice& block_device) {
+    return NameFromFixedArray(block_device.partition_name, sizeof(block_device.partition_name));
+}
+
 }  // namespace fs_mgr
 }  // namespace android
diff --git a/fs_mgr/liblp/reader.h b/fs_mgr/liblp/reader.h
index 24b2611..d5d5188 100644
--- a/fs_mgr/liblp/reader.h
+++ b/fs_mgr/liblp/reader.h
@@ -31,7 +31,6 @@
 bool ParseGeometry(const void* buffer, LpMetadataGeometry* geometry);
 
 // Helper functions for manually reading geometry and metadata.
-std::unique_ptr<LpMetadata> ReadMetadata(int fd, uint32_t slot_number);
 std::unique_ptr<LpMetadata> ParseMetadata(const LpMetadataGeometry& geometry, int fd);
 std::unique_ptr<LpMetadata> ParseMetadata(const LpMetadataGeometry& geometry, const void* buffer,
                                           size_t size);
diff --git a/fs_mgr/liblp/test_partition_opener.cpp b/fs_mgr/liblp/test_partition_opener.cpp
new file mode 100644
index 0000000..c796f6c
--- /dev/null
+++ b/fs_mgr/liblp/test_partition_opener.cpp
@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2018 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 "test_partition_opener.h"
+
+#include <errno.h>
+
+namespace android {
+namespace fs_mgr {
+
+using android::base::unique_fd;
+
+TestPartitionOpener::TestPartitionOpener(
+        const std::map<std::string, int>& partition_map,
+        const std::map<std::string, BlockDeviceInfo>& partition_info)
+    : partition_map_(partition_map), partition_info_(partition_info) {}
+
+unique_fd TestPartitionOpener::Open(const std::string& partition_name, int flags) const {
+    auto iter = partition_map_.find(partition_name);
+    if (iter == partition_map_.end()) {
+        errno = ENOENT;
+        return {};
+    }
+    return unique_fd{dup(iter->second)};
+}
+
+bool TestPartitionOpener::GetInfo(const std::string& partition_name, BlockDeviceInfo* info) const {
+    auto iter = partition_info_.find(partition_name);
+    if (iter == partition_info_.end()) {
+        errno = ENOENT;
+        return false;
+    }
+    *info = iter->second;
+    return true;
+}
+
+}  // namespace fs_mgr
+}  // namespace android
diff --git a/fs_mgr/liblp/test_partition_opener.h b/fs_mgr/liblp/test_partition_opener.h
new file mode 100644
index 0000000..b90fee7
--- /dev/null
+++ b/fs_mgr/liblp/test_partition_opener.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2018 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 <map>
+#include <string>
+
+#include <android-base/unique_fd.h>
+#include <liblp/partition_opener.h>
+
+namespace android {
+namespace fs_mgr {
+
+class TestPartitionOpener : public PartitionOpener {
+  public:
+    explicit TestPartitionOpener(const std::map<std::string, int>& partition_map,
+                                 const std::map<std::string, BlockDeviceInfo>& partition_info = {});
+
+    android::base::unique_fd Open(const std::string& partition_name, int flags) const override;
+    bool GetInfo(const std::string& partition_name, BlockDeviceInfo* info) const override;
+
+  private:
+    std::map<std::string, int> partition_map_;
+    std::map<std::string, BlockDeviceInfo> partition_info_;
+};
+
+}  // namespace fs_mgr
+}  // namespace android
diff --git a/fs_mgr/liblp/utility.cpp b/fs_mgr/liblp/utility.cpp
index 0556833..742ad82 100644
--- a/fs_mgr/liblp/utility.cpp
+++ b/fs_mgr/liblp/utility.cpp
@@ -16,7 +16,6 @@
 
 #include <fcntl.h>
 #include <stdint.h>
-#include <sys/ioctl.h>
 #include <sys/stat.h>
 #include <unistd.h>
 
@@ -66,11 +65,8 @@
 
 int64_t GetPrimaryMetadataOffset(const LpMetadataGeometry& geometry, uint32_t slot_number) {
     CHECK(slot_number < geometry.metadata_slot_count);
-
     int64_t offset = LP_PARTITION_RESERVED_BYTES + (LP_METADATA_GEOMETRY_SIZE * 2) +
                      geometry.metadata_max_size * slot_number;
-    CHECK(offset + geometry.metadata_max_size <=
-          int64_t(geometry.first_logical_sector * LP_SECTOR_SIZE));
     return offset;
 }
 
@@ -81,6 +77,18 @@
     return start + int64_t(geometry.metadata_max_size * slot_number);
 }
 
+uint64_t GetTotalMetadataSize(uint32_t metadata_max_size, uint32_t max_slots) {
+    return LP_PARTITION_RESERVED_BYTES +
+           (LP_METADATA_GEOMETRY_SIZE + metadata_max_size * max_slots) * 2;
+}
+
+const LpMetadataBlockDevice* GetMetadataSuperBlockDevice(const LpMetadata& metadata) {
+    if (metadata.block_devices.empty()) {
+        return nullptr;
+    }
+    return &metadata.block_devices[0];
+}
+
 void SHA256(const void* data, size_t length, uint8_t out[32]) {
     SHA256_CTX c;
     SHA256_Init(&c);
@@ -100,5 +108,13 @@
     return suffix[1] - 'a';
 }
 
+uint64_t GetTotalSuperPartitionSize(const LpMetadata& metadata) {
+    uint64_t size = 0;
+    for (const auto& block_device : metadata.block_devices) {
+        size += block_device.size;
+    }
+    return size;
+}
+
 }  // namespace fs_mgr
 }  // namespace android
diff --git a/fs_mgr/liblp/utility.h b/fs_mgr/liblp/utility.h
index 61e7d31..65e643b 100644
--- a/fs_mgr/liblp/utility.h
+++ b/fs_mgr/liblp/utility.h
@@ -23,7 +23,7 @@
 
 #include <android-base/logging.h>
 
-#include "liblp/metadata_format.h"
+#include "liblp/liblp.h"
 
 #define LP_TAG "[liblp]"
 #define LWARN LOG(WARNING) << LP_TAG
@@ -50,6 +50,10 @@
 // device.
 int64_t GetBackupMetadataOffset(const LpMetadataGeometry& geometry, uint32_t slot_number);
 
+// Return the total space at the start of the super partition that must be set
+// aside from headers/metadata and backups.
+uint64_t GetTotalMetadataSize(uint32_t metadata_max_size, uint32_t max_slots);
+
 // Cross-platform helper for lseek64().
 int64_t SeekFile64(int fd, int64_t offset, int whence);
 
diff --git a/fs_mgr/liblp/utility_test.cpp b/fs_mgr/liblp/utility_test.cpp
index 8baf9e7..bdf6dfd 100644
--- a/fs_mgr/liblp/utility_test.cpp
+++ b/fs_mgr/liblp/utility_test.cpp
@@ -36,10 +36,6 @@
                                    {0},
                                    16384,
                                    4,
-                                   10000,
-                                   0,
-                                   0,
-                                   1024 * 1024,
                                    4096};
     static const uint64_t start = LP_PARTITION_RESERVED_BYTES;
     EXPECT_EQ(GetPrimaryMetadataOffset(geometry, 0), start + 8192);
diff --git a/fs_mgr/liblp/writer.cpp b/fs_mgr/liblp/writer.cpp
index f857d8c..c740bd4 100644
--- a/fs_mgr/liblp/writer.cpp
+++ b/fs_mgr/liblp/writer.cpp
@@ -43,9 +43,7 @@
 static bool CompareGeometry(const LpMetadataGeometry& g1, const LpMetadataGeometry& g2) {
     return g1.metadata_max_size == g2.metadata_max_size &&
            g1.metadata_slot_count == g2.metadata_slot_count &&
-           g1.block_device_size == g2.block_device_size &&
-           g1.logical_block_size == g2.logical_block_size &&
-           g1.first_logical_sector == g2.first_logical_sector;
+           g1.logical_block_size == g2.logical_block_size;
 }
 
 std::string SerializeMetadata(const LpMetadata& input) {
@@ -59,15 +57,18 @@
                         metadata.extents.size() * sizeof(LpMetadataExtent));
     std::string groups(reinterpret_cast<const char*>(metadata.groups.data()),
                        metadata.groups.size() * sizeof(LpMetadataPartitionGroup));
+    std::string block_devices(reinterpret_cast<const char*>(metadata.block_devices.data()),
+                              metadata.block_devices.size() * sizeof(LpMetadataBlockDevice));
 
     // Compute positions of tables.
     header.partitions.offset = 0;
     header.extents.offset = header.partitions.offset + partitions.size();
     header.groups.offset = header.extents.offset + extents.size();
-    header.tables_size = header.groups.offset + groups.size();
+    header.block_devices.offset = header.groups.offset + groups.size();
+    header.tables_size = header.block_devices.offset + block_devices.size();
 
     // Compute payload checksum.
-    std::string tables = partitions + extents + groups;
+    std::string tables = partitions + extents + groups + block_devices;
     SHA256(tables.data(), tables.size(), header.tables_checksum);
 
     // Compute header checksum.
@@ -105,14 +106,20 @@
                              uint64_t(geometry.metadata_max_size) * geometry.metadata_slot_count;
     uint64_t total_reserved = reserved_size * 2;
 
+    const LpMetadataBlockDevice* super_device = GetMetadataSuperBlockDevice(metadata);
+    if (!super_device) {
+        LERROR << "Logical partition metadata does not have a super block device.";
+        return false;
+    }
+
     if (total_reserved > blockdevice_size ||
-        total_reserved > geometry.first_logical_sector * LP_SECTOR_SIZE) {
+        total_reserved > super_device->first_logical_sector * LP_SECTOR_SIZE) {
         LERROR << "Not enough space to store all logical partition metadata slots.";
         return false;
     }
-    if (blockdevice_size != metadata.geometry.block_device_size) {
+    if (blockdevice_size != super_device->size) {
         LERROR << "Block device size " << blockdevice_size
-               << " does not match metadata requested size " << metadata.geometry.block_device_size;
+               << " does not match metadata requested size " << super_device->size;
         return false;
     }
 
@@ -125,11 +132,11 @@
     }
 
     // Make sure all linear extents have a valid range.
-    uint64_t last_sector = geometry.block_device_size / LP_SECTOR_SIZE;
+    uint64_t last_sector = super_device->size / LP_SECTOR_SIZE;
     for (const auto& extent : metadata.extents) {
         if (extent.target_type == LP_TARGET_TYPE_LINEAR) {
             uint64_t physical_sector = extent.target_data;
-            if (physical_sector < geometry.first_logical_sector ||
+            if (physical_sector < super_device->first_logical_sector ||
                 physical_sector + extent.num_sectors > last_sector) {
                 LERROR << "Extent table entry is out of bounds.";
                 return false;
@@ -139,10 +146,28 @@
     return true;
 }
 
-static bool WritePrimaryMetadata(int fd, const LpMetadataGeometry& geometry, uint32_t slot_number,
+// Check that the given region is within metadata bounds.
+static bool ValidateMetadataRegion(const LpMetadata& metadata, uint64_t start, size_t size) {
+    const LpMetadataBlockDevice* super_device = GetMetadataSuperBlockDevice(metadata);
+    if (!super_device) {
+        LERROR << __PRETTY_FUNCTION__ << " could not locate super block device in metadata";
+        return false;
+    }
+    if (start + size >= super_device->first_logical_sector * LP_SECTOR_SIZE) {
+        LERROR << __PRETTY_FUNCTION__ << " write of " << size << " bytes at " << start
+               << " overlaps with logical partition contents";
+        return false;
+    }
+    return true;
+}
+
+static bool WritePrimaryMetadata(int fd, const LpMetadata& metadata, uint32_t slot_number,
                                  const std::string& blob,
                                  const std::function<bool(int, const std::string&)>& writer) {
-    int64_t primary_offset = GetPrimaryMetadataOffset(geometry, slot_number);
+    int64_t primary_offset = GetPrimaryMetadataOffset(metadata.geometry, slot_number);
+    if (!ValidateMetadataRegion(metadata, primary_offset, blob.size())) {
+        return false;
+    }
     if (SeekFile64(fd, primary_offset, SEEK_SET) < 0) {
         PERROR << __PRETTY_FUNCTION__ << " lseek failed: offset " << primary_offset;
         return false;
@@ -154,18 +179,15 @@
     return true;
 }
 
-static bool WriteBackupMetadata(int fd, const LpMetadataGeometry& geometry, uint32_t slot_number,
+static bool WriteBackupMetadata(int fd, const LpMetadata& metadata, uint32_t slot_number,
                                 const std::string& blob,
                                 const std::function<bool(int, const std::string&)>& writer) {
-    int64_t backup_offset = GetBackupMetadataOffset(geometry, slot_number);
-    int64_t abs_offset = SeekFile64(fd, backup_offset, SEEK_SET);
-    if (abs_offset == (int64_t)-1) {
-        PERROR << __PRETTY_FUNCTION__ << " lseek failed: offset " << backup_offset;
+    int64_t backup_offset = GetBackupMetadataOffset(metadata.geometry, slot_number);
+    if (!ValidateMetadataRegion(metadata, backup_offset, blob.size())) {
         return false;
     }
-    if (abs_offset >= int64_t(geometry.first_logical_sector) * LP_SECTOR_SIZE) {
-        PERROR << __PRETTY_FUNCTION__ << " backup offset " << abs_offset
-               << " is within logical partition bounds, sector " << geometry.first_logical_sector;
+    if (SeekFile64(fd, backup_offset, SEEK_SET) < 0) {
+        PERROR << __PRETTY_FUNCTION__ << " lseek failed: offset " << backup_offset;
         return false;
     }
     if (!writer(fd, blob)) {
@@ -175,18 +197,18 @@
     return true;
 }
 
-static bool WriteMetadata(int fd, const LpMetadataGeometry& geometry, uint32_t slot_number,
+static bool WriteMetadata(int fd, const LpMetadata& metadata, uint32_t slot_number,
                           const std::string& blob,
                           const std::function<bool(int, const std::string&)>& writer) {
     // Make sure we're writing to a valid metadata slot.
-    if (slot_number >= geometry.metadata_slot_count) {
+    if (slot_number >= metadata.geometry.metadata_slot_count) {
         LERROR << "Invalid logical partition metadata slot number.";
         return false;
     }
-    if (!WritePrimaryMetadata(fd, geometry, slot_number, blob, writer)) {
+    if (!WritePrimaryMetadata(fd, metadata, slot_number, blob, writer)) {
         return false;
     }
-    if (!WriteBackupMetadata(fd, geometry, slot_number, blob, writer)) {
+    if (!WriteBackupMetadata(fd, metadata, slot_number, blob, writer)) {
         return false;
     }
     return true;
@@ -196,7 +218,14 @@
     return android::base::WriteFully(fd, blob.data(), blob.size());
 }
 
-bool FlashPartitionTable(int fd, const LpMetadata& metadata) {
+bool FlashPartitionTable(const IPartitionOpener& opener, const std::string& super_partition,
+                         const LpMetadata& metadata) {
+    android::base::unique_fd fd = opener.Open(super_partition, O_RDWR | O_SYNC);
+    if (fd < 0) {
+        PERROR << __PRETTY_FUNCTION__ << " open failed: " << super_partition;
+        return false;
+    }
+
     // Before writing geometry and/or logical partition tables, perform some
     // basic checks that the geometry and tables are coherent, and will fit
     // on the given block device.
@@ -216,6 +245,8 @@
         return false;
     }
 
+    LWARN << "Flashing new logical partition geometry to " << super_partition;
+
     // Write geometry to the primary and backup locations.
     std::string blob = SerializeGeometry(metadata.geometry);
     if (SeekFile64(fd, GetPrimaryGeometryOffset(), SEEK_SET) < 0) {
@@ -237,18 +268,29 @@
 
     bool ok = true;
     for (size_t i = 0; i < metadata.geometry.metadata_slot_count; i++) {
-        ok &= WriteMetadata(fd, metadata.geometry, i, metadata_blob, DefaultWriter);
+        ok &= WriteMetadata(fd, metadata, i, metadata_blob, DefaultWriter);
     }
     return ok;
 }
 
+bool FlashPartitionTable(const std::string& super_partition, const LpMetadata& metadata) {
+    return FlashPartitionTable(PartitionOpener(), super_partition, metadata);
+}
+
 static bool CompareMetadata(const LpMetadata& a, const LpMetadata& b) {
     return !memcmp(a.header.header_checksum, b.header.header_checksum,
                    sizeof(a.header.header_checksum));
 }
 
-bool UpdatePartitionTable(int fd, const LpMetadata& metadata, uint32_t slot_number,
+bool UpdatePartitionTable(const IPartitionOpener& opener, const std::string& super_partition,
+                          const LpMetadata& metadata, uint32_t slot_number,
                           const std::function<bool(int, const std::string&)>& writer) {
+    android::base::unique_fd fd = opener.Open(super_partition, O_RDWR | O_SYNC);
+    if (fd < 0) {
+        PERROR << __PRETTY_FUNCTION__ << " open failed: " << super_partition;
+        return false;
+    }
+
     // Before writing geometry and/or logical partition tables, perform some
     // basic checks that the geometry and tables are coherent, and will fit
     // on the given block device.
@@ -289,7 +331,7 @@
             LERROR << "Error serializing primary metadata to repair corrupted backup";
             return false;
         }
-        if (!WriteBackupMetadata(fd, geometry, slot_number, old_blob, writer)) {
+        if (!WriteBackupMetadata(fd, metadata, slot_number, old_blob, writer)) {
             LERROR << "Error writing primary metadata to repair corrupted backup";
             return false;
         }
@@ -301,46 +343,31 @@
             LERROR << "Error serializing primary metadata to repair corrupted backup";
             return false;
         }
-        if (!WritePrimaryMetadata(fd, geometry, slot_number, old_blob, writer)) {
+        if (!WritePrimaryMetadata(fd, metadata, slot_number, old_blob, writer)) {
             LERROR << "Error writing primary metadata to repair corrupted backup";
             return false;
         }
     }
 
     // Both copies should now be in sync, so we can continue the update.
-    return WriteMetadata(fd, geometry, slot_number, blob, writer);
-}
+    if (!WriteMetadata(fd, metadata, slot_number, blob, writer)) {
+        return false;
+    }
 
-bool FlashPartitionTable(const std::string& block_device, const LpMetadata& metadata) {
-    android::base::unique_fd fd(open(block_device.c_str(), O_RDWR | O_SYNC));
-    if (fd < 0) {
-        PERROR << __PRETTY_FUNCTION__ << " open failed: " << block_device;
-        return false;
-    }
-    if (!FlashPartitionTable(fd, metadata)) {
-        return false;
-    }
-    LWARN << "Flashed new logical partition geometry to " << block_device;
-    return true;
-}
-
-bool UpdatePartitionTable(const std::string& block_device, const LpMetadata& metadata,
-                          uint32_t slot_number) {
-    android::base::unique_fd fd(open(block_device.c_str(), O_RDWR | O_SYNC));
-    if (fd < 0) {
-        PERROR << __PRETTY_FUNCTION__ << " open failed: " << block_device;
-        return false;
-    }
-    if (!UpdatePartitionTable(fd, metadata, slot_number)) {
-        return false;
-    }
     LINFO << "Updated logical partition table at slot " << slot_number << " on device "
-          << block_device;
+          << super_partition;
     return true;
 }
 
-bool UpdatePartitionTable(int fd, const LpMetadata& metadata, uint32_t slot_number) {
-    return UpdatePartitionTable(fd, metadata, slot_number, DefaultWriter);
+bool UpdatePartitionTable(const IPartitionOpener& opener, const std::string& super_partition,
+                          const LpMetadata& metadata, uint32_t slot_number) {
+    return UpdatePartitionTable(opener, super_partition, metadata, slot_number, DefaultWriter);
+}
+
+bool UpdatePartitionTable(const std::string& super_partition, const LpMetadata& metadata,
+                          uint32_t slot_number) {
+    PartitionOpener opener;
+    return UpdatePartitionTable(opener, super_partition, metadata, slot_number, DefaultWriter);
 }
 
 }  // namespace fs_mgr
diff --git a/fs_mgr/liblp/writer.h b/fs_mgr/liblp/writer.h
index ab18d45..6f1da0f 100644
--- a/fs_mgr/liblp/writer.h
+++ b/fs_mgr/liblp/writer.h
@@ -30,10 +30,8 @@
 
 // These variants are for testing only. The path-based functions should be used
 // for actual operation, so that open() is called with the correct flags.
-bool FlashPartitionTable(int fd, const LpMetadata& metadata);
-bool UpdatePartitionTable(int fd, const LpMetadata& metadata, uint32_t slot_number);
-
-bool UpdatePartitionTable(int fd, const LpMetadata& metadata, uint32_t slot_number,
+bool UpdatePartitionTable(const IPartitionOpener& opener, const std::string& super_partition,
+                          const LpMetadata& metadata, uint32_t slot_number,
                           const std::function<bool(int, const std::string&)>& writer);
 
 }  // namespace fs_mgr
diff --git a/libmetricslogger/Android.bp b/libmetricslogger/Android.bp
index 1551b5b..2d327ee 100644
--- a/libmetricslogger/Android.bp
+++ b/libmetricslogger/Android.bp
@@ -11,7 +11,11 @@
 
     export_include_dirs: ["include"],
     local_include_dirs: ["include"],
-    shared_libs: ["liblog"],
+    shared_libs: [
+        "libbase",
+        "liblog",
+        "libstatssocket",
+    ],
     whole_static_libs: ["libgtest_prod"],
 
     cflags: [
@@ -23,17 +27,20 @@
 
 // metricslogger shared library
 // -----------------------------------------------------------------------------
-cc_library_shared {
+cc_library {
     name: "libmetricslogger",
     srcs: metricslogger_lib_src_files,
     defaults: ["metricslogger_defaults"],
+    export_shared_lib_headers: ["libstatssocket"],
 }
 
 // static version of libmetricslogger, needed by a few art static binaries
+// TODO(b/117829226): Remove once dependencies are cleaned up.
 cc_library_static {
     name: "libmetricslogger_static",
     srcs: metricslogger_lib_src_files,
     defaults: ["metricslogger_defaults"],
+    export_shared_lib_headers: ["libstatssocket"],
 }
 
 // metricslogger shared library, debug
diff --git a/libmetricslogger/include/metricslogger/metrics_logger.h b/libmetricslogger/include/metricslogger/metrics_logger.h
index c305db2..56bd6c4 100644
--- a/libmetricslogger/include/metricslogger/metrics_logger.h
+++ b/libmetricslogger/include/metricslogger/metrics_logger.h
@@ -15,6 +15,7 @@
  */
 
 #include <log/log_event_list.h>
+#include <stats_event_list.h>
 #include <cstdint>
 #include <string>
 
@@ -43,6 +44,7 @@
 class ComplexEventLogger {
   private:
     android_log_event_list logger;
+    stats_event_list stats_logger;
 
   public:
     // Create a complex event with category|category|.
diff --git a/libmetricslogger/metrics_logger.cpp b/libmetricslogger/metrics_logger.cpp
index 6a32153..2a1b137 100644
--- a/libmetricslogger/metrics_logger.cpp
+++ b/libmetricslogger/metrics_logger.cpp
@@ -18,11 +18,15 @@
 
 #include <cstdlib>
 
+#include <android-base/chrono_utils.h>
 #include <log/event_tag_map.h>
-#include <log/log_event_list.h>
+
+using namespace android;
 
 namespace {
 
+const static int kStatsEventTag = 1937006964;
+const static int kKeyValuePairAtomId = 83;
 #ifdef __ANDROID__
 EventTagMap* kEventTagMap = android_openEventTagMap(nullptr);
 const int kSysuiMultiActionTag = android_lookupEventTagNum(
@@ -32,6 +36,12 @@
 const int kSysuiMultiActionTag = 0;
 #endif
 
+int64_t getElapsedTimeNanoSinceBoot() {
+    return std::chrono::duration_cast<std::chrono::nanoseconds>(
+                   android::base::boot_clock::now().time_since_epoch())
+            .count();
+}
+
 }  // namespace
 
 namespace android {
@@ -42,6 +52,12 @@
     android_log_event_list log(kSysuiMultiActionTag);
     log << LOGBUILDER_CATEGORY << LOGBUILDER_HISTOGRAM << LOGBUILDER_NAME << event
         << LOGBUILDER_BUCKET << data << LOGBUILDER_VALUE << 1 << LOG_ID_EVENTS;
+
+    stats_event_list stats_log(kStatsEventTag);
+    stats_log << getElapsedTimeNanoSinceBoot() << kKeyValuePairAtomId << LOGBUILDER_CATEGORY
+              << LOGBUILDER_HISTOGRAM << LOGBUILDER_NAME << event << LOGBUILDER_BUCKET << data
+              << LOGBUILDER_VALUE << 1;
+    stats_log.write(LOG_ID_STATS);
 }
 
 // Mirror com.android.internal.logging.MetricsLogger#count().
@@ -49,6 +65,11 @@
     android_log_event_list log(kSysuiMultiActionTag);
     log << LOGBUILDER_CATEGORY << LOGBUILDER_COUNTER << LOGBUILDER_NAME << name << LOGBUILDER_VALUE
         << val << LOG_ID_EVENTS;
+
+    stats_event_list stats_log(kStatsEventTag);
+    stats_log << getElapsedTimeNanoSinceBoot() << kKeyValuePairAtomId << LOGBUILDER_CATEGORY
+              << LOGBUILDER_COUNTER << LOGBUILDER_NAME << name << LOGBUILDER_VALUE << val;
+    stats_log.write(LOG_ID_STATS);
 }
 
 // Mirror com.android.internal.logging.MetricsLogger#action().
@@ -56,34 +77,48 @@
     android_log_event_list log(kSysuiMultiActionTag);
     log << LOGBUILDER_CATEGORY << category << LOGBUILDER_TYPE << TYPE_ACTION
         << field << value << LOG_ID_EVENTS;
+
+    stats_event_list stats_log(kStatsEventTag);
+    stats_log << getElapsedTimeNanoSinceBoot() << kKeyValuePairAtomId << LOGBUILDER_CATEGORY
+              << category << LOGBUILDER_TYPE << TYPE_ACTION << field << value;
+    stats_log.write(LOG_ID_STATS);
 }
 
-ComplexEventLogger::ComplexEventLogger(int category) : logger(kSysuiMultiActionTag) {
+ComplexEventLogger::ComplexEventLogger(int category)
+    : logger(kSysuiMultiActionTag), stats_logger(kStatsEventTag) {
     logger << LOGBUILDER_CATEGORY << category;
+    stats_logger << getElapsedTimeNanoSinceBoot() << kKeyValuePairAtomId << LOGBUILDER_CATEGORY
+                 << category;
 }
 
 void ComplexEventLogger::SetPackageName(const std::string& package_name) {
     logger << LOGBUILDER_PACKAGENAME << package_name;
+    stats_logger << LOGBUILDER_PACKAGENAME << package_name;
 }
 
 void ComplexEventLogger::AddTaggedData(int tag, int32_t value) {
     logger << tag << value;
+    stats_logger << tag << value;
 }
 
 void ComplexEventLogger::AddTaggedData(int tag, const std::string& value) {
     logger << tag << value;
+    stats_logger << tag << value;
 }
 
 void ComplexEventLogger::AddTaggedData(int tag, int64_t value) {
     logger << tag << value;
+    stats_logger << tag << value;
 }
 
 void ComplexEventLogger::AddTaggedData(int tag, float value) {
     logger << tag << value;
+    stats_logger << tag << value;
 }
 
 void ComplexEventLogger::Record() {
     logger << LOG_ID_EVENTS;
+    stats_logger.write(LOG_ID_STATS);
 }
 
 }  // namespace metricslogger
diff --git a/libstats/Android.bp b/libstats/Android.bp
index d58f294..f5ee1da 100644
--- a/libstats/Android.bp
+++ b/libstats/Android.bp
@@ -17,12 +17,13 @@
 // ==========================================================
 // Native library to write stats log to statsd socket
 // ==========================================================
-cc_library_static {
+cc_library {
     name: "libstatssocket",
     srcs: [
         "stats_event_list.c",
         "statsd_writer.c",
     ],
+    host_supported: true,
     cflags: [
         "-Wall",
         "-Werror",
@@ -32,6 +33,7 @@
     ],
     export_include_dirs: ["include"],
     shared_libs: [
+        "libcutils",
         "liblog",
     ],
 }
diff --git a/libstats/stats_event_list.c b/libstats/stats_event_list.c
index 8eedc60..72770d4 100644
--- a/libstats/stats_event_list.c
+++ b/libstats/stats_event_list.c
@@ -17,6 +17,7 @@
 #include "include/stats_event_list.h"
 
 #include <string.h>
+#include <sys/time.h>
 #include "statsd_writer.h"
 
 #define MAX_EVENT_PAYLOAD (LOGGER_ENTRY_MAX_PAYLOAD - sizeof(int32_t))
@@ -156,7 +157,14 @@
     }
 
     save_errno = errno;
+#if defined(__ANDROID__)
     clock_gettime(CLOCK_REALTIME, &ts);
+#else
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    ts.tv_sec = tv.tv_sec;
+    ts.tv_nsec = tv.tv_usec * 1000;
+#endif
 
     int ret = (int)(*statsdLoggerWrite.write)(&ts, vec, nr);
     errno = save_errno;
diff --git a/libstats/statsd_writer.c b/libstats/statsd_writer.c
index afe401f..88f7d44 100644
--- a/libstats/statsd_writer.c
+++ b/libstats/statsd_writer.c
@@ -15,8 +15,9 @@
  */
 #include "statsd_writer.h"
 
+#include <cutils/fs.h>
 #include <cutils/sockets.h>
-#include <endian.h>
+#include <cutils/threads.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <inttypes.h>
@@ -37,6 +38,14 @@
 /* branchless on many architectures. */
 #define min(x, y) ((y) ^ (((x) ^ (y)) & -((x) < (y))))
 
+#ifndef htole32
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+#define htole32(x) (x)
+#else
+#define htole32(x) __bswap_32(x)
+#endif
+#endif
+
 static pthread_mutex_t log_init_lock = PTHREAD_MUTEX_INITIALIZER;
 static atomic_int dropped = 0;
 
@@ -78,7 +87,14 @@
 
     i = atomic_load(&statsdLoggerWrite.sock);
     if (i < 0) {
-        int sock = TEMP_FAILURE_RETRY(socket(PF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0));
+        int flags = SOCK_DGRAM;
+#ifdef SOCK_CLOEXEC
+        flags |= SOCK_CLOEXEC;
+#endif
+#ifdef SOCK_NONBLOCK
+        flags |= SOCK_NONBLOCK;
+#endif
+        int sock = TEMP_FAILURE_RETRY(socket(PF_UNIX, flags, 0));
         if (sock < 0) {
             ret = -errno;
         } else {
diff --git a/lmkd/include/lmkd.h b/lmkd/include/lmkd.h
index e8f51da..e72d159 100644
--- a/lmkd/include/lmkd.h
+++ b/lmkd/include/lmkd.h
@@ -31,6 +31,7 @@
     LMK_PROCPRIO,    /* Register a process and set its oom_adj_score */
     LMK_PROCREMOVE,  /* Unregister a process */
     LMK_PROCPURGE,   /* Purge all registered processes */
+    LMK_GETKILLCNT,  /* Get number of kills */
 };
 
 /*
@@ -152,6 +153,44 @@
     return sizeof(int);
 }
 
+/* LMK_GETKILLCNT packet payload */
+struct lmk_getkillcnt {
+    int min_oomadj;
+    int max_oomadj;
+};
+
+/*
+ * For LMK_GETKILLCNT packet get its payload.
+ * Warning: no checks performed, caller should ensure valid parameters.
+ */
+inline void lmkd_pack_get_getkillcnt(LMKD_CTRL_PACKET packet,
+                                   struct lmk_getkillcnt *params) {
+    params->min_oomadj = ntohl(packet[1]);
+    params->max_oomadj = ntohl(packet[2]);
+}
+
+/*
+ * Prepare LMK_GETKILLCNT packet and return packet size in bytes.
+ * Warning: no checks performed, caller should ensure valid parameters.
+ */
+inline size_t lmkd_pack_set_getkillcnt(LMKD_CTRL_PACKET packet,
+                                       struct lmk_getkillcnt *params) {
+    packet[0] = htonl(LMK_GETKILLCNT);
+    packet[1] = htonl(params->min_oomadj);
+    packet[2] = htonl(params->max_oomadj);
+    return 3 * sizeof(int);
+}
+
+/*
+ * Prepare LMK_GETKILLCNT reply packet and return packet size in bytes.
+ * Warning: no checks performed, caller should ensure valid parameters.
+ */
+inline size_t lmkd_pack_set_getkillcnt_repl(LMKD_CTRL_PACKET packet, int kill_cnt) {
+    packet[0] = htonl(LMK_GETKILLCNT);
+    packet[1] = htonl(kill_cnt);
+    return 2 * sizeof(int);
+}
+
 __END_DECLS
 
 #endif /* _LMKD_H_ */
diff --git a/lmkd/lmkd.c b/lmkd/lmkd.c
index 0a469e8..e3c4ccc 100644
--- a/lmkd/lmkd.c
+++ b/lmkd/lmkd.c
@@ -313,7 +313,20 @@
 #define pid_hashfn(x) ((((x) >> 8) ^ (x)) & (PIDHASH_SZ - 1))
 
 #define ADJTOSLOT(adj) ((adj) + -OOM_SCORE_ADJ_MIN)
-static struct adjslot_list procadjslot_list[ADJTOSLOT(OOM_SCORE_ADJ_MAX) + 1];
+#define ADJTOSLOT_COUNT (ADJTOSLOT(OOM_SCORE_ADJ_MAX) + 1)
+static struct adjslot_list procadjslot_list[ADJTOSLOT_COUNT];
+
+#define MAX_DISTINCT_OOM_ADJ 32
+#define KILLCNT_INVALID_IDX 0xFF
+/*
+ * Because killcnt array is sparse a two-level indirection is used
+ * to keep the size small. killcnt_idx stores index of the element in
+ * killcnt array. Index KILLCNT_INVALID_IDX indicates an unused slot.
+ */
+static uint8_t killcnt_idx[ADJTOSLOT_COUNT];
+static uint16_t killcnt[MAX_DISTINCT_OOM_ADJ];
+static int killcnt_free_idx = 0;
+static uint32_t killcnt_total = 0;
 
 /* PAGE_SIZE / 1024 */
 static long page_k;
@@ -644,6 +657,67 @@
     memset(&pidhash[0], 0, sizeof(pidhash));
 }
 
+static void inc_killcnt(int oomadj) {
+    int slot = ADJTOSLOT(oomadj);
+    uint8_t idx = killcnt_idx[slot];
+
+    if (idx == KILLCNT_INVALID_IDX) {
+        /* index is not assigned for this oomadj */
+        if (killcnt_free_idx < MAX_DISTINCT_OOM_ADJ) {
+            killcnt_idx[slot] = killcnt_free_idx;
+            killcnt[killcnt_free_idx] = 1;
+            killcnt_free_idx++;
+        } else {
+            ALOGW("Number of distinct oomadj levels exceeds %d",
+                MAX_DISTINCT_OOM_ADJ);
+        }
+    } else {
+        /*
+         * wraparound is highly unlikely and is detectable using total
+         * counter because it has to be equal to the sum of all counters
+         */
+        killcnt[idx]++;
+    }
+    /* increment total kill counter */
+    killcnt_total++;
+}
+
+static int get_killcnt(int min_oomadj, int max_oomadj) {
+    int slot;
+    int count = 0;
+
+    if (min_oomadj > max_oomadj)
+        return 0;
+
+    /* special case to get total kill count */
+    if (min_oomadj > OOM_SCORE_ADJ_MAX)
+        return killcnt_total;
+
+    while (min_oomadj <= max_oomadj &&
+           (slot = ADJTOSLOT(min_oomadj)) < ADJTOSLOT_COUNT) {
+        uint8_t idx = killcnt_idx[slot];
+        if (idx != KILLCNT_INVALID_IDX) {
+            count += killcnt[idx];
+        }
+        min_oomadj++;
+    }
+
+    return count;
+}
+
+static int cmd_getkillcnt(LMKD_CTRL_PACKET packet) {
+    struct lmk_getkillcnt params;
+
+    if (use_inkernel_interface) {
+        /* kernel driver does not expose this information */
+        return 0;
+    }
+
+    lmkd_pack_get_getkillcnt(packet, &params);
+
+    return get_killcnt(params.min_oomadj, params.max_oomadj);
+}
+
 static void cmd_target(int ntargets, LMKD_CTRL_PACKET packet) {
     int i;
     struct lmk_target target;
@@ -748,12 +822,28 @@
     return ret;
 }
 
+static int ctrl_data_write(int dsock_idx, char *buf, size_t bufsz) {
+    int ret = 0;
+
+    ret = TEMP_FAILURE_RETRY(write(data_sock[dsock_idx].sock, buf, bufsz));
+
+    if (ret == -1) {
+        ALOGE("control data socket write failed; errno=%d", errno);
+    } else if (ret == 0) {
+        ALOGE("Got EOF on control data socket");
+        ret = -1;
+    }
+
+    return ret;
+}
+
 static void ctrl_command_handler(int dsock_idx) {
     LMKD_CTRL_PACKET packet;
     int len;
     enum lmk_cmd cmd;
     int nargs;
     int targets;
+    int kill_cnt;
 
     len = ctrl_data_read(dsock_idx, (char *)packet, CTRL_PACKET_MAX_SIZE);
     if (len <= 0)
@@ -791,6 +881,14 @@
             goto wronglen;
         cmd_procpurge();
         break;
+    case LMK_GETKILLCNT:
+        if (nargs != 2)
+            goto wronglen;
+        kill_cnt = cmd_getkillcnt(packet);
+        len = lmkd_pack_set_getkillcnt_repl(packet, kill_cnt);
+        if (ctrl_data_write(dsock_idx, (char *)packet, len) != len)
+            return;
+        break;
     default:
         ALOGE("Received unknown command code %d", cmd);
         return;
@@ -1200,6 +1298,7 @@
 
     /* CAP_KILL required */
     r = kill(pid, SIGKILL);
+    inc_killcnt(procp->oomadj);
     ALOGI("Kill '%s' (%d), uid %d, oom_adj %d to free %ldkB",
         taskname, pid, uid, procp->oomadj, tasksize * page_k);
 
@@ -1700,6 +1799,8 @@
         procadjslot_list[i].prev = &procadjslot_list[i];
     }
 
+    memset(killcnt_idx, KILLCNT_INVALID_IDX, sizeof(killcnt_idx));
+
     return 0;
 }