diff --git a/fastboot/Android.bp b/fastboot/Android.bp
index 43b2ddd..ce702a0 100644
--- a/fastboot/Android.bp
+++ b/fastboot/Android.bp
@@ -183,6 +183,7 @@
     ],
 
     static_libs: [
+        "libc++fs",
         "libgtest_prod",
         "libhealthhalutils",
         "libsnapshot_cow",
diff --git a/fs_mgr/libsnapshot/Android.bp b/fs_mgr/libsnapshot/Android.bp
index ea92d25..3cb4123 100644
--- a/fs_mgr/libsnapshot/Android.bp
+++ b/fs_mgr/libsnapshot/Android.bp
@@ -264,6 +264,7 @@
         "android.hardware.boot@1.0",
         "android.hardware.boot@1.1",
         "libbrotli",
+        "libc++fs",
         "libfs_mgr",
         "libgsi",
         "libgmock",
@@ -297,6 +298,7 @@
     ],
     static_libs: [
         "libbrotli",
+        "libc++fs",
         "libfstab",
         "libsnapshot",
         "libsnapshot_cow",
@@ -326,6 +328,7 @@
         "power_test.cpp",
     ],
     static_libs: [
+        "libc++fs",
         "libsnapshot",
         "update_metadata-protos",
     ],
@@ -355,6 +358,7 @@
     static_libs: [
         "libbase",
         "libbrotli",
+        "libc++fs",
         "libchrome",
         "libcrypto_static",
         "libcutils",
@@ -416,7 +420,7 @@
         "snapuserd_server.cpp",
         "snapuserd.cpp",
         "snapuserd_daemon.cpp",
-	"snapuserd_worker.cpp",
+        "snapuserd_worker.cpp",
     ],
 
     cflags: [
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
index 7e74fac..126e1a0 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/snapshot.h
@@ -493,6 +493,9 @@
     // Unmap a COW image device previously mapped with MapCowImage().
     bool UnmapCowImage(const std::string& name);
 
+    // Unmap a COW and remove it from a MetadataBuilder.
+    void UnmapAndDeleteCowPartition(MetadataBuilder* current_metadata);
+
     // Unmap and remove all known snapshots.
     bool RemoveAllSnapshots(LockedFile* lock);
 
@@ -738,6 +741,10 @@
     // Helper of UpdateUsesCompression
     bool UpdateUsesCompression(LockedFile* lock);
 
+    // Wrapper around libdm, with diagnostics.
+    bool DeleteDeviceIfExists(const std::string& name,
+                              const std::chrono::milliseconds& timeout_ms = {});
+
     std::string gsid_dir_;
     std::string metadata_dir_;
     std::unique_ptr<IDeviceInfo> device_;
diff --git a/fs_mgr/libsnapshot/snapshot.cpp b/fs_mgr/libsnapshot/snapshot.cpp
index a0a1e4f..c504355 100644
--- a/fs_mgr/libsnapshot/snapshot.cpp
+++ b/fs_mgr/libsnapshot/snapshot.cpp
@@ -21,6 +21,7 @@
 #include <sys/types.h>
 #include <sys/unistd.h>
 
+#include <filesystem>
 #include <optional>
 #include <thread>
 #include <unordered_set>
@@ -587,8 +588,7 @@
 bool SnapshotManager::UnmapSnapshot(LockedFile* lock, const std::string& name) {
     CHECK(lock);
 
-    auto& dm = DeviceMapper::Instance();
-    if (!dm.DeleteDeviceIfExists(name)) {
+    if (!DeleteDeviceIfExists(name)) {
         LOG(ERROR) << "Could not delete snapshot device: " << name;
         return false;
     }
@@ -1252,25 +1252,6 @@
     return true;
 }
 
-static bool DeleteDmDevice(const std::string& name, const std::chrono::milliseconds& timeout_ms) {
-    auto start = std::chrono::steady_clock::now();
-    auto& dm = DeviceMapper::Instance();
-    while (true) {
-        if (dm.DeleteDeviceIfExists(name)) {
-            break;
-        }
-        auto now = std::chrono::steady_clock::now();
-        auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(now - start);
-        if (elapsed >= timeout_ms) {
-            LOG(ERROR) << "DeleteDevice timeout: " << name;
-            return false;
-        }
-        std::this_thread::sleep_for(400ms);
-    }
-
-    return true;
-}
-
 bool SnapshotManager::CollapseSnapshotDevice(const std::string& name,
                                              const SnapshotStatus& status) {
     auto& dm = DeviceMapper::Instance();
@@ -1326,11 +1307,11 @@
         UnmapDmUserDevice(name);
     }
     auto base_name = GetBaseDeviceName(name);
-    if (!dm.DeleteDeviceIfExists(base_name)) {
+    if (!DeleteDeviceIfExists(base_name)) {
         LOG(ERROR) << "Unable to delete base device for snapshot: " << base_name;
     }
 
-    if (!DeleteDmDevice(GetSourceDeviceName(name), 4000ms)) {
+    if (!DeleteDeviceIfExists(GetSourceDeviceName(name), 4000ms)) {
         LOG(ERROR) << "Unable to delete source device for snapshot: " << GetSourceDeviceName(name);
     }
 
@@ -2083,15 +2064,14 @@
         return false;
     }
 
-    auto& dm = DeviceMapper::Instance();
     auto base_name = GetBaseDeviceName(target_partition_name);
-    if (!dm.DeleteDeviceIfExists(base_name)) {
+    if (!DeleteDeviceIfExists(base_name)) {
         LOG(ERROR) << "Cannot delete base device: " << base_name;
         return false;
     }
 
     auto source_name = GetSourceDeviceName(target_partition_name);
-    if (!dm.DeleteDeviceIfExists(source_name)) {
+    if (!DeleteDeviceIfExists(source_name)) {
         LOG(ERROR) << "Cannot delete source device: " << source_name;
         return false;
     }
@@ -2181,7 +2161,7 @@
         return false;
     }
 
-    if (!DeleteDmDevice(GetCowName(name), 4000ms)) {
+    if (!DeleteDeviceIfExists(GetCowName(name), 4000ms)) {
         LOG(ERROR) << "Cannot unmap: " << GetCowName(name);
         return false;
     }
@@ -2202,7 +2182,7 @@
         return true;
     }
 
-    if (!dm.DeleteDeviceIfExists(dm_user_name)) {
+    if (!DeleteDeviceIfExists(dm_user_name)) {
         LOG(ERROR) << "Cannot unmap " << dm_user_name;
         return false;
     }
@@ -2593,11 +2573,10 @@
     return true;
 }
 
-static void UnmapAndDeleteCowPartition(MetadataBuilder* current_metadata) {
-    auto& dm = DeviceMapper::Instance();
+void SnapshotManager::UnmapAndDeleteCowPartition(MetadataBuilder* current_metadata) {
     std::vector<std::string> to_delete;
     for (auto* existing_cow_partition : current_metadata->ListPartitionsInGroup(kCowGroupName)) {
-        if (!dm.DeleteDeviceIfExists(existing_cow_partition->name())) {
+        if (!DeleteDeviceIfExists(existing_cow_partition->name())) {
             LOG(WARNING) << existing_cow_partition->name()
                          << " cannot be unmapped and its space cannot be reclaimed";
             continue;
@@ -3626,5 +3605,71 @@
     stats->set_estimated_cow_size_bytes(estimated_cow_size);
 }
 
+bool SnapshotManager::DeleteDeviceIfExists(const std::string& name,
+                                           const std::chrono::milliseconds& timeout_ms) {
+    auto& dm = DeviceMapper::Instance();
+    auto start = std::chrono::steady_clock::now();
+    while (true) {
+        if (dm.DeleteDeviceIfExists(name)) {
+            return true;
+        }
+        auto now = std::chrono::steady_clock::now();
+        auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(now - start);
+        if (elapsed >= timeout_ms) {
+            break;
+        }
+        std::this_thread::sleep_for(400ms);
+    }
+
+    // Try to diagnose why this failed. First get the actual device path.
+    std::string full_path;
+    if (!dm.GetDmDevicePathByName(name, &full_path)) {
+        LOG(ERROR) << "Unable to diagnose DM_DEV_REMOVE failure.";
+        return false;
+    }
+
+    // Check for child dm-devices.
+    std::string block_name = android::base::Basename(full_path);
+    std::string sysfs_holders = "/sys/class/block/" + block_name + "/holders";
+
+    std::error_code ec;
+    std::filesystem::directory_iterator dir_iter(sysfs_holders, ec);
+    if (auto begin = std::filesystem::begin(dir_iter); begin != std::filesystem::end(dir_iter)) {
+        LOG(ERROR) << "Child device-mapper device still mapped: " << begin->path();
+        return false;
+    }
+
+    // Check for mounted partitions.
+    android::fs_mgr::Fstab fstab;
+    android::fs_mgr::ReadFstabFromFile("/proc/mounts", &fstab);
+    for (const auto& entry : fstab) {
+        if (android::base::Basename(entry.blk_device) == block_name) {
+            LOG(ERROR) << "Partition still mounted: " << entry.mount_point;
+            return false;
+        }
+    }
+
+    // Check for detached mounted partitions.
+    for (const auto& fs : std::filesystem::directory_iterator("/sys/fs", ec)) {
+        std::string fs_type = android::base::Basename(fs.path().c_str());
+        if (!(fs_type == "ext4" || fs_type == "f2fs")) {
+            continue;
+        }
+
+        std::string path = fs.path().c_str() + "/"s + block_name;
+        if (access(path.c_str(), F_OK) == 0) {
+            LOG(ERROR) << "Block device was lazily unmounted and is still in-use: " << full_path
+                       << "; possibly open file descriptor or attached loop device.";
+            return false;
+        }
+    }
+
+    LOG(ERROR) << "Device-mapper device " << name << "(" << full_path << ")"
+               << " still in use."
+               << "  Probably a file descriptor was leaked or held open, or a loop device is"
+               << " attached.";
+    return false;
+}
+
 }  // namespace snapshot
 }  // namespace android
diff --git a/init/init.cpp b/init/init.cpp
index 7264b22..a7325ca 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -849,21 +849,6 @@
     auto is_installed = android::gsi::IsGsiInstalled() ? "1" : "0";
     SetProperty(gsi::kGsiInstalledProp, is_installed);
 
-    /*
-     * For debug builds of S launching devices, init mounts debugfs for
-     * enabling vendor debug data collection setup at boot time. Init will unmount it on
-     * boot-complete after vendor code has performed the required initializations
-     * during boot. Dumpstate will then mount debugfs in order to read data
-     * from the same using the dumpstate HAL during bugreport creation.
-     * Dumpstate will also unmount debugfs after bugreport creation.
-     * first_api_level comparison is done here instead
-     * of init.rc since init.rc parser does not support >/< operators.
-     */
-    auto api_level = android::base::GetIntProperty("ro.product.first_api_level", 0);
-    bool is_debuggable = android::base::GetBoolProperty("ro.debuggable", false);
-    auto mount_debugfs = (is_debuggable && (api_level >= 31)) ? "1" : "0";
-    SetProperty("init.mount_debugfs", mount_debugfs);
-
     am.QueueBuiltinAction(SetupCgroupsAction, "SetupCgroups");
     am.QueueBuiltinAction(SetKptrRestrictAction, "SetKptrRestrict");
     am.QueueBuiltinAction(TestPerfEventSelinuxAction, "TestPerfEventSelinux");
diff --git a/libutils/String8.cpp b/libutils/String8.cpp
index 3dc2026..fad130b 100644
--- a/libutils/String8.cpp
+++ b/libutils/String8.cpp
@@ -415,50 +415,28 @@
 
 void String8::toLower()
 {
-    toLower(0, size());
-}
+    const size_t length = size();
+    if (length == 0) return;
 
-void String8::toLower(size_t start, size_t length)
-{
-    const size_t len = size();
-    if (start >= len) {
-        return;
-    }
-    if (start+length > len) {
-        length = len-start;
-    }
-    char* buf = lockBuffer(len);
-    buf += start;
-    while (length > 0) {
+    char* buf = lockBuffer(length);
+    for (size_t i = length; i > 0; --i) {
         *buf = static_cast<char>(tolower(*buf));
         buf++;
-        length--;
     }
-    unlockBuffer(len);
+    unlockBuffer(length);
 }
 
 void String8::toUpper()
 {
-    toUpper(0, size());
-}
+    const size_t length = size();
+    if (length == 0) return;
 
-void String8::toUpper(size_t start, size_t length)
-{
-    const size_t len = size();
-    if (start >= len) {
-        return;
-    }
-    if (start+length > len) {
-        length = len-start;
-    }
-    char* buf = lockBuffer(len);
-    buf += start;
-    while (length > 0) {
+    char* buf = lockBuffer(length);
+    for (size_t i = length; i > 0; --i) {
         *buf = static_cast<char>(toupper(*buf));
         buf++;
-        length--;
     }
-    unlockBuffer(len);
+    unlockBuffer(length);
 }
 
 // ---------------------------------------------------------------------------
diff --git a/libutils/include/utils/String8.h b/libutils/include/utils/String8.h
index 0bcb716..84f14d0 100644
--- a/libutils/include/utils/String8.h
+++ b/libutils/include/utils/String8.h
@@ -130,9 +130,7 @@
             bool                removeAll(const char* other);
 
             void                toLower();
-            void                toLower(size_t start, size_t numChars);
             void                toUpper();
-            void                toUpper(size_t start, size_t numChars);
 
 
     /*
diff --git a/rootdir/etc/linker.config.json b/rootdir/etc/linker.config.json
index 83cb6ff..d9f5526 100644
--- a/rootdir/etc/linker.config.json
+++ b/rootdir/etc/linker.config.json
@@ -1,8 +1,7 @@
 {
   "requireLibs": [
-    // Keep in sync with the "platform" namespace in art/build/apex/ld.config.txt.
-    "libdexfile_external.so",
-    "libdexfiled_external.so",
+    "libdexfile.so",
+    "libdexfiled.so",
     "libnativebridge.so",
     "libnativehelper.so",
     "libnativeloader.so",
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 9a30ead..5a9cc99 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -985,7 +985,7 @@
     write /proc/sys/vm/dirty_expire_centisecs 200
     write /proc/sys/vm/dirty_background_ratio  5
 
-on property:sys.boot_completed=1 && property:init.mount_debugfs=1
+on property:sys.boot_completed=1 && property:ro.product.enforce_debugfs_restrictions=true
    umount /sys/kernel/debug
 
 on boot
@@ -1263,7 +1263,7 @@
 on property:sys.boot_completed=1 && property:sys.init.userspace_reboot.in_progress=1
   setprop sys.init.userspace_reboot.in_progress ""
 
-on early-init && property:init.mount_debugfs=1
+on early-init && property:ro.product.enforce_debugfs_restrictions=true
     mount debugfs debugfs /sys/kernel/debug
     chmod 0755 /sys/kernel/debug