diff --git a/adb/client/adb_client.cpp b/adb/client/adb_client.cpp
index 4cf3a74..9fa827d 100644
--- a/adb/client/adb_client.cpp
+++ b/adb/client/adb_client.cpp
@@ -31,10 +31,12 @@
 
 #include <condition_variable>
 #include <mutex>
+#include <optional>
 #include <string>
 #include <thread>
 #include <vector>
 
+#include <android-base/file.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
 #include <android-base/thread_annotations.h>
@@ -214,15 +216,26 @@
     return adb_connect(nullptr, service, error);
 }
 
-int adb_connect(TransportId* transport, std::string_view service, std::string* error) {
-    // first query the adb server's version
+#if defined(__linux__)
+std::optional<std::string> adb_get_server_executable_path() {
+    int port;
+    std::string error;
+    if (!parse_tcp_socket_spec(__adb_server_socket_spec, nullptr, &port, nullptr, &error)) {
+        LOG(FATAL) << "failed to parse server socket spec: " << error;
+    }
+
+    return adb_get_android_dir_path() + OS_PATH_SEPARATOR + "adb." + std::to_string(port);
+}
+#endif
+
+static bool __adb_check_server_version(std::string* error) {
     unique_fd fd(_adb_connect("host:version", nullptr, error));
 
-    LOG(DEBUG) << "adb_connect: service: " << service;
-    if (fd == -2 && !is_local_socket_spec(__adb_server_socket_spec)) {
+    bool local = is_local_socket_spec(__adb_server_socket_spec);
+    if (fd == -2 && !local) {
         fprintf(stderr, "* cannot start server on remote host\n");
         // error is the original network connection error
-        return fd;
+        return false;
     } else if (fd == -2) {
         fprintf(stderr, "* daemon not running; starting now at %s\n", __adb_server_socket_spec);
     start_server:
@@ -232,7 +245,7 @@
             // return a generic error string about the overall adb_connect()
             // that the caller requested.
             *error = "cannot connect to daemon";
-            return -1;
+            return false;
         } else {
             fprintf(stderr, "* daemon started successfully\n");
         }
@@ -254,18 +267,39 @@
             if (sscanf(&version_string[0], "%04x", &version) != 1) {
                 *error = android::base::StringPrintf("cannot parse version string: %s",
                                                      version_string.c_str());
-                return -1;
+                return false;
             }
         } else {
             // If fd is -1 check for "unknown host service" which would
             // indicate a version of adb that does not support the
             // version command, in which case we should fall-through to kill it.
             if (*error != "unknown host service") {
-                return fd;
+                return false;
             }
         }
 
         if (version != ADB_SERVER_VERSION) {
+#if defined(__linux__)
+            if (version > ADB_SERVER_VERSION && local) {
+                // Try to re-exec the existing adb server's binary.
+                constexpr const char* adb_reexeced = "adb (re-execed)";
+                if (strcmp(adb_reexeced, *__adb_argv) != 0) {
+                    __adb_argv[0] = adb_reexeced;
+                    std::optional<std::string> server_path_path = adb_get_server_executable_path();
+                    std::string server_path;
+                    if (server_path_path &&
+                        android::base::ReadFileToString(*server_path_path, &server_path)) {
+                        if (execve(server_path.c_str(), const_cast<char**>(__adb_argv),
+                                   const_cast<char**>(__adb_envp)) == -1) {
+                            LOG(ERROR) << "failed to exec newer version at " << server_path;
+                        }
+
+                        // Fall-through to restarting the server.
+                    }
+                }
+            }
+#endif
+
             fprintf(stderr, "adb server version (%d) doesn't match this client (%d); killing...\n",
                     version, ADB_SERVER_VERSION);
             adb_kill_server();
@@ -273,12 +307,36 @@
         }
     }
 
+    return true;
+}
+
+bool adb_check_server_version(std::string* error) {
+    // Only check the version once per process, since this isn't atomic anyway.
+    static std::once_flag once;
+    static bool result;
+    static std::string* err;
+    std::call_once(once, []() {
+        err = new std::string();
+        result = __adb_check_server_version(err);
+    });
+    *error = *err;
+    return result;
+}
+
+int adb_connect(TransportId* transport, std::string_view service, std::string* error) {
+    LOG(DEBUG) << "adb_connect: service: " << service;
+
+    // Query the adb server's version.
+    if (!adb_check_server_version(error)) {
+        return -1;
+    }
+
     // if the command is start-server, we are done.
     if (service == "host:start-server") {
         return 0;
     }
 
-    fd.reset(_adb_connect(service, transport, error));
+    unique_fd fd(_adb_connect(service, transport, error));
     if (fd == -1) {
         D("_adb_connect error: %s", error->c_str());
     } else if(fd == -2) {
diff --git a/adb/client/adb_client.h b/adb/client/adb_client.h
index 0a73787..8d32c93 100644
--- a/adb/client/adb_client.h
+++ b/adb/client/adb_client.h
@@ -20,8 +20,14 @@
 #include "sysdeps.h"
 #include "transport.h"
 
+#include <optional>
 #include <string>
 
+// Explicitly check the adb server version.
+// All of the commands below do this implicitly.
+// Only the first invocation of this function will check the server version.
+bool adb_check_server_version(std::string* _Nonnull error);
+
 // Connect to adb, connect to the named service, and return a valid fd for
 // interacting with that service upon success or a negative number on failure.
 int adb_connect(std::string_view service, std::string* _Nonnull error);
@@ -65,3 +71,13 @@
 
 // Get the feature set of the current preferred transport.
 bool adb_get_feature_set(FeatureSet* _Nonnull feature_set, std::string* _Nonnull error);
+
+#if defined(__linux__)
+// Get the path of a file containing the path to the server executable, if the socket spec set via
+// adb_set_socket_spec is a local one.
+std::optional<std::string> adb_get_server_executable_path();
+#endif
+
+// Globally acccesible argv/envp, for the purpose of re-execing adb.
+extern const char* _Nullable * _Nullable __adb_argv;
+extern const char* _Nullable * _Nullable __adb_envp;
diff --git a/adb/client/commandline.cpp b/adb/client/commandline.cpp
index 3d5d9db..bb30ae5 100644
--- a/adb/client/commandline.cpp
+++ b/adb/client/commandline.cpp
@@ -1303,9 +1303,9 @@
     }
 }
 
-static int adb_connect_command(const std::string& command) {
+static int adb_connect_command(const std::string& command, TransportId* transport = nullptr) {
     std::string error;
-    unique_fd fd(adb_connect(command, &error));
+    unique_fd fd(adb_connect(transport, command, &error));
     if (fd < 0) {
         fprintf(stderr, "error: %s\n", error.c_str());
         return 1;
@@ -1394,9 +1394,9 @@
     TransportId transport_id = 0;
 
     while (argc > 0) {
-        if (!strcmp(argv[0],"server")) {
+        if (!strcmp(argv[0], "server")) {
             is_server = true;
-        } else if (!strcmp(argv[0],"nodaemon")) {
+        } else if (!strcmp(argv[0], "nodaemon")) {
             no_daemon = true;
         } else if (!strcmp(argv[0], "fork-server")) {
             /* this is a special flag used only when the ADB client launches the ADB Server */
@@ -1433,11 +1433,11 @@
             if (*id != '\0') {
                 error_exit("invalid transport id");
             }
-        } else if (!strcmp(argv[0],"-d")) {
+        } else if (!strcmp(argv[0], "-d")) {
             transport_type = kTransportUsb;
-        } else if (!strcmp(argv[0],"-e")) {
+        } else if (!strcmp(argv[0], "-e")) {
             transport_type = kTransportLocal;
-        } else if (!strcmp(argv[0],"-a")) {
+        } else if (!strcmp(argv[0], "-a")) {
             gListenAll = 1;
         } else if (!strncmp(argv[0], "-H", 2)) {
             if (argv[0][2] == '\0') {
@@ -1569,6 +1569,10 @@
         }
 
         std::string query = android::base::StringPrintf("host:%s%s", argv[0], listopt);
+        std::string error;
+        if (!adb_check_server_version(&error)) {
+            error_exit("failed to check server version: %s", error.c_str());
+        }
         printf("List of devices attached\n");
         return adb_query_command(query);
     }
diff --git a/adb/client/main.cpp b/adb/client/main.cpp
index 2ee81a9..0c5c28f 100644
--- a/adb/client/main.cpp
+++ b/adb/client/main.cpp
@@ -32,12 +32,16 @@
 
 #include "adb.h"
 #include "adb_auth.h"
+#include "adb_client.h"
 #include "adb_listeners.h"
 #include "adb_utils.h"
 #include "commandline.h"
 #include "sysdeps/chrono.h"
 #include "transport.h"
 
+const char** __adb_argv;
+const char** __adb_envp;
+
 static void setup_daemon_logging() {
     const std::string log_file_path(GetLogFilePath());
     int fd = unix_open(log_file_path, O_WRONLY | O_CREAT | O_APPEND, 0640);
@@ -191,13 +195,29 @@
         notify_thread.detach();
     }
 
+#if defined(__linux__)
+    // Write our location to .android/adb.$PORT, so that older clients can exec us.
+    std::string path;
+    if (!android::base::Readlink("/proc/self/exe", &path)) {
+        PLOG(ERROR) << "failed to readlink /proc/self/exe";
+    }
+
+    std::optional<std::string> server_executable_path = adb_get_server_executable_path();
+    if (server_executable_path) {
+      if (!android::base::WriteStringToFile(path, *server_executable_path)) {
+          PLOG(ERROR) << "failed to write server path to " << path;
+      }
+    }
+#endif
+
     D("Event loop starting");
     fdevent_loop();
-
     return 0;
 }
 
-int main(int argc, char** argv) {
+int main(int argc, char* argv[], char* envp[]) {
+    __adb_argv = const_cast<const char**>(argv);
+    __adb_envp = const_cast<const char**>(envp);
     adb_trace_init(argv);
     return adb_commandline(argc - 1, const_cast<const char**>(argv + 1));
 }
diff --git a/adb/socket_spec.h b/adb/socket_spec.h
index 687d751..7cc2fac 100644
--- a/adb/socket_spec.h
+++ b/adb/socket_spec.h
@@ -29,6 +29,5 @@
                          std::string* error);
 int socket_spec_listen(std::string_view spec, std::string* error, int* resolved_tcp_port = nullptr);
 
-// Exposed for testing.
 bool parse_tcp_socket_spec(std::string_view spec, std::string* hostname, int* port,
                            std::string* serial, std::string* error);
diff --git a/init/Android.bp b/init/Android.bp
index 9aeb837..8a0bb55 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -110,6 +110,7 @@
         "init.cpp",
         "keychords.cpp",
         "modalias_handler.cpp",
+        "mount_handler.cpp",
         "mount_namespace.cpp",
         "parser.cpp",
         "persistent_properties.cpp",
diff --git a/init/README.md b/init/README.md
index f0e5d55..b2039b4 100644
--- a/init/README.md
+++ b/init/README.md
@@ -660,12 +660,19 @@
 
 Properties
 ----------
-Init provides information about the services that it is responsible
-for via the below properties.
+Init provides state information with the following properties.
 
 `init.svc.<name>`
 > State of a named service ("stopped", "stopping", "running", "restarting")
 
+`dev.mnt.blk.<mount_point>`
+> Block device base name associated with a *mount_point*.
+  The *mount_point* has / replaced by . and if referencing the root mount point
+  "/", it will use "/root", specifically `dev.mnt.blk.root`.
+  Meant for references to `/sys/device/block/${dev.mnt.blk.<mount_point>}/` and
+  `/sys/fs/ext4/${dev.mnt.blk.<mount_point>}/` to tune the block device
+  characteristics in a device agnostic manner.
+
 
 Boot timing
 -----------
diff --git a/init/init.cpp b/init/init.cpp
index 7182fda..a5f4549 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -57,6 +57,7 @@
 #include "first_stage_mount.h"
 #include "import_parser.h"
 #include "keychords.h"
+#include "mount_handler.h"
 #include "mount_namespace.h"
 #include "property_service.h"
 #include "reboot.h"
@@ -686,6 +687,7 @@
     fs_mgr_vendor_overlay_mount_all();
     export_oem_lock_status();
     StartPropertyService(&epoll);
+    MountHandler mount_handler(&epoll);
     set_usb_controller();
 
     const BuiltinFunctionMap function_map;
diff --git a/init/mount_handler.cpp b/init/mount_handler.cpp
new file mode 100644
index 0000000..12dfc6d
--- /dev/null
+++ b/init/mount_handler.cpp
@@ -0,0 +1,140 @@
+/*
+ * Copyright (C) 2019 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 "mount_handler.h"
+
+#include <ctype.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/epoll.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <algorithm>
+#include <string>
+#include <utility>
+
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/properties.h>
+#include <android-base/strings.h>
+#include <fs_mgr.h>
+#include <fstab/fstab.h>
+
+#include "epoll.h"
+#include "property_service.h"
+
+namespace android {
+namespace init {
+
+namespace {
+
+MountHandlerEntry ParseMount(const std::string& line) {
+    auto fields = android::base::Split(line, " ");
+    while (fields.size() < 3) fields.emplace_back("");
+    if (fields[0] == "/dev/root") {
+        if (android::fs_mgr::Fstab fstab; android::fs_mgr::ReadDefaultFstab(&fstab)) {
+            if (auto entry = GetEntryForMountPoint(&fstab, "/")) {
+                fields[0] = entry->blk_device;
+            }
+        }
+    }
+    if (android::base::StartsWith(fields[0], "/dev/")) {
+        if (std::string link; android::base::Readlink(fields[0], &link)) {
+            fields[0] = link;
+        }
+    }
+    return MountHandlerEntry(fields[0], fields[1], fields[2]);
+}
+
+void SetMountProperty(const MountHandlerEntry& entry, bool add) {
+    static constexpr char devblock[] = "/dev/block/";
+    if (!android::base::StartsWith(entry.blk_device, devblock)) return;
+    std::string value;
+    if (add) {
+        value = entry.blk_device.substr(strlen(devblock));
+        if (android::base::StartsWith(value, "sd")) {
+            // All sd partitions inherit their queue characteristics
+            // from the whole device reference.  Strip partition number.
+            auto it = std::find_if(value.begin(), value.end(), [](char c) { return isdigit(c); });
+            if (it != value.end()) value.erase(it, value.end());
+        }
+        auto queue = "/sys/block/" + value + "/queue";
+        struct stat sb;
+        if (stat(queue.c_str(), &sb) || !S_ISDIR(sb.st_mode)) value = "";
+        if (stat(entry.mount_point.c_str(), &sb) || !S_ISDIR(sb.st_mode)) value = "";
+        // Skip the noise associated with APEX until there is a need
+        if (android::base::StartsWith(value, "loop")) value = "";
+    }
+    std::string property =
+            "dev.mnt.blk" + ((entry.mount_point == "/") ? "/root" : entry.mount_point);
+    std::replace(property.begin(), property.end(), '/', '.');
+    if (value.empty() && android::base::GetProperty(property, "").empty()) return;
+    property_set(property, value);
+}
+
+}  // namespace
+
+MountHandlerEntry::MountHandlerEntry(const std::string& blk_device, const std::string& mount_point,
+                                     const std::string& fs_type)
+    : blk_device(blk_device), mount_point(mount_point), fs_type(fs_type) {}
+
+bool MountHandlerEntry::operator<(const MountHandlerEntry& r) const {
+    if (blk_device < r.blk_device) return true;
+    if (blk_device > r.blk_device) return false;
+    if (mount_point < r.mount_point) return true;
+    if (mount_point > r.mount_point) return false;
+    return fs_type < r.fs_type;
+}
+
+MountHandler::MountHandler(Epoll* epoll) : epoll_(epoll), fp_(fopen("/proc/mounts", "re"), fclose) {
+    if (!fp_) PLOG(FATAL) << "Could not open /proc/mounts";
+    auto result = epoll->RegisterHandler(
+            fileno(fp_.get()), [this]() { this->MountHandlerFunction(); }, EPOLLERR | EPOLLPRI);
+    if (!result) LOG(FATAL) << result.error();
+}
+
+MountHandler::~MountHandler() {
+    if (fp_) epoll_->UnregisterHandler(fileno(fp_.get())).IgnoreError();
+}
+
+void MountHandler::MountHandlerFunction() {
+    rewind(fp_.get());
+    char* buf = nullptr;
+    size_t len = 0;
+    auto untouched = mounts_;
+    while (getline(&buf, &len, fp_.get()) != -1) {
+        auto entry = ParseMount(std::string(buf, len));
+        auto match = untouched.find(entry);
+        if (match == untouched.end()) {
+            SetMountProperty(entry, true);
+            mounts_.emplace(std::move(entry));
+        } else {
+            untouched.erase(match);
+        }
+    }
+    free(buf);
+    for (auto entry : untouched) {
+        auto match = mounts_.find(entry);
+        if (match == mounts_.end()) continue;
+        mounts_.erase(match);
+        SetMountProperty(entry, false);
+    }
+}
+
+}  // namespace init
+}  // namespace android
diff --git a/init/mount_handler.h b/init/mount_handler.h
new file mode 100644
index 0000000..e524a74
--- /dev/null
+++ b/init/mount_handler.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2019 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 <stdio.h>
+
+#include <memory>
+#include <set>
+#include <string>
+
+#include "epoll.h"
+
+namespace android {
+namespace init {
+
+struct MountHandlerEntry {
+    MountHandlerEntry(const std::string& blk_device, const std::string& mount_point,
+                      const std::string& fs_type);
+
+    bool operator<(const MountHandlerEntry& r) const;
+
+    const std::string blk_device;
+    const std::string mount_point;
+    const std::string fs_type;
+};
+
+class MountHandler {
+  public:
+    explicit MountHandler(Epoll* epoll);
+    MountHandler(const MountHandler&) = delete;
+    MountHandler(MountHandler&&) = delete;
+    MountHandler& operator=(const MountHandler&) = delete;
+    MountHandler& operator=(MountHandler&&) = delete;
+    ~MountHandler();
+
+  private:
+    void MountHandlerFunction();
+
+    Epoll* epoll_;
+    std::unique_ptr<FILE, decltype(&fclose)> fp_;
+    std::set<MountHandlerEntry> mounts_;
+};
+
+}  // namespace init
+}  // namespace android