Merge changes from topic "apex_earlymount_no_bionic_bindmount"

* changes:
  /bionic path is gone
  Revert "Handle adb sync with Bionic under /bionic"
  Don't bind-mount bionic files
diff --git a/adb/daemon/file_sync_service.cpp b/adb/daemon/file_sync_service.cpp
index 70deb31..29bd798 100644
--- a/adb/daemon/file_sync_service.cpp
+++ b/adb/daemon/file_sync_service.cpp
@@ -25,7 +25,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/mount.h>
 #include <sys/stat.h>
 #include <sys/time.h>
 #include <sys/types.h>
@@ -211,22 +210,6 @@
     return WriteFdExactly(s, &msg.dent, sizeof(msg.dent));
 }
 
-static bool is_mountpoint(const std::string& path, pid_t tid) {
-    const std::string mountinfo_path = "/proc/" + std::to_string(tid) + "/mountinfo";
-    std::string mountinfo;
-    if (!android::base::ReadFileToString(mountinfo_path, &mountinfo)) {
-        PLOG(ERROR) << "Failed to open " << mountinfo_path;
-        return false;
-    }
-    std::vector<std::string> lines = android::base::Split(mountinfo, "\n");
-    return std::find_if(lines.begin(), lines.end(), [&path](const auto& line) {
-               auto tokens = android::base::Split(line, " ");
-               // line format is ...
-               // mountid parentmountid major:minor sourcepath targetpath option ...
-               return tokens.size() >= 4 && tokens[4] == path;
-           }) != lines.end();
-}
-
 // Make sure that SendFail from adb_io.cpp isn't accidentally used in this file.
 #pragma GCC poison SendFail
 
@@ -432,18 +415,6 @@
     struct stat st;
     bool do_unlink = (lstat(path.c_str(), &st) == -1) || S_ISREG(st.st_mode) ||
                      (S_ISLNK(st.st_mode) && !S_ISLNK(mode));
-
-    // If the path is a file that is a mount point, don't unlink it, but instead
-    // truncate to zero. If unlinked, existing mounts on the path is all
-    // unmounted
-    if (S_ISREG(st.st_mode) && is_mountpoint(path, getpid())) {
-        do_unlink = false;
-        if (truncate(path.c_str(), 0) == -1) {
-            SendSyncFail(s, "truncate to zero failed");
-            return false;
-        }
-    }
-
     if (do_unlink) {
         adb_unlink(path.c_str());
     }
@@ -591,64 +562,7 @@
     return true;
 }
 
-#if defined(__ANDROID__)
-class FileSyncPreparer {
-  public:
-    FileSyncPreparer() : saved_ns_fd_(-1), rooted_(getuid() == 0) {
-        const std::string namespace_path = "/proc/" + std::to_string(gettid()) + "/ns/mnt";
-        const int ns_fd = adb_open(namespace_path.c_str(), O_RDONLY | O_CLOEXEC);
-        if (ns_fd == -1) {
-            if (rooted_) PLOG(ERROR) << "Failed to save mount namespace";
-            return;
-        }
-        saved_ns_fd_.reset(ns_fd);
-
-        // Note: this is for the current thread only
-        if (unshare(CLONE_NEWNS) != 0) {
-            if (rooted_) PLOG(ERROR) << "Failed to clone mount namespace";
-            return;
-        }
-
-        // Set the propagation type of / to private so that unmount below is
-        // not propagated to other mount namespaces.
-        if (mount(nullptr, "/", nullptr, MS_PRIVATE | MS_REC, nullptr) == -1) {
-            if (rooted_) PLOG(ERROR) << "Could not change propagation type of / to MS_PRIVATE";
-            return;
-        }
-
-        // unmount /bionic which is bind-mount to itself by init. Under /bionic,
-        // there are other bind mounts for the bionic files. By unmounting this,
-        // we unmount them all thus revealing the raw file system that is the
-        // same as the local file system seen by the adb client.
-        if (umount2("/bionic", MNT_DETACH) == -1 && errno != ENOENT) {
-            if (rooted_) PLOG(ERROR) << "Could not unmount /bionic to reveal raw filesystem";
-            return;
-        }
-    }
-
-    ~FileSyncPreparer() {
-        if (saved_ns_fd_.get() != -1) {
-            // In fact, this is not strictly required because this thread for file
-            // sync service will be destroyed after the current transfer is all
-            // done. However, let's restore the ns in case the same thread is
-            // reused by multiple transfers in the future refactoring.
-            if (setns(saved_ns_fd_, CLONE_NEWNS) == -1) {
-                PLOG(ERROR) << "Failed to restore saved mount namespace";
-            }
-        }
-    }
-
-  private:
-    unique_fd saved_ns_fd_;
-    bool rooted_;
-};
-#endif
-
 void file_sync_service(unique_fd fd) {
-#if defined(__ANDROID__)
-    FileSyncPreparer preparer;
-#endif
-
     std::vector<char> buffer(SYNC_DATA_MAX);
 
     while (handle_sync_command(fd.get(), buffer)) {
diff --git a/fs_mgr/fs_mgr_remount.cpp b/fs_mgr/fs_mgr_remount.cpp
index 5c4008c..e2a4d16 100644
--- a/fs_mgr/fs_mgr_remount.cpp
+++ b/fs_mgr/fs_mgr_remount.cpp
@@ -80,29 +80,6 @@
     return &(*it);
 }
 
-void try_unmount_bionic(android::fs_mgr::Fstab* mounts) {
-    static constexpr const char* kBionic = "/bionic";
-
-    auto entry = GetEntryForMountPoint(mounts, kBionic);
-    if (!entry) return;
-
-    struct statfs buf;
-    if (::statfs(kBionic, &buf) == -1) {
-        PLOG(ERROR) << "statfs of " << kBionic;
-        return;
-    }
-    if (buf.f_flags & MS_RDONLY) {
-        // /bionic is on a read-only partition; can happen for
-        // non-system-as-root-devices. Don' try to unmount.
-        return;
-    }
-    fs_mgr_set_blk_ro(entry->blk_device, false);
-    if (::mount(entry->blk_device.c_str(), entry->mount_point.c_str(), entry->fs_type.c_str(),
-                MS_REMOUNT, nullptr) == -1) {
-        PLOG(ERROR) << "remount of " << kBionic;
-    }
-}
-
 void MyLogger(android::base::LogId id, android::base::LogSeverity severity, const char* tag,
               const char* file, unsigned int line, const char* message) {
     static const char log_characters[] = "VD\0WEFF";
@@ -395,7 +372,5 @@
 
     if (reboot_later) reboot(false);
 
-    try_unmount_bionic(&mounts);
-
     return retval;
 }
diff --git a/init/builtins.cpp b/init/builtins.cpp
index 6511d29..8437e37 100644
--- a/init/builtins.cpp
+++ b/init/builtins.cpp
@@ -1118,14 +1118,6 @@
     }
 }
 
-static Result<Success> do_setup_runtime_bionic(const BuiltinArguments& args) {
-    if (SetupRuntimeBionic()) {
-        return Success();
-    } else {
-        return Error() << "Failed to setup runtime bionic";
-    }
-}
-
 static Result<Success> do_enter_default_mount_ns(const BuiltinArguments& args) {
     if (SwitchToDefaultMountNamespace()) {
         return Success();
@@ -1181,7 +1173,6 @@
         {"rmdir",                   {1,     1,    {true,   do_rmdir}}},
         {"setprop",                 {2,     2,    {true,   do_setprop}}},
         {"setrlimit",               {3,     3,    {false,  do_setrlimit}}},
-        {"setup_runtime_bionic",    {0,     0,    {false,  do_setup_runtime_bionic}}},
         {"start",                   {1,     1,    {false,  do_start}}},
         {"stop",                    {1,     1,    {false,  do_stop}}},
         {"swapon_all",              {1,     1,    {false,  do_swapon_all}}},
diff --git a/init/mount_namespace.cpp b/init/mount_namespace.cpp
index 4161df2..5305dc7 100644
--- a/init/mount_namespace.cpp
+++ b/init/mount_namespace.cpp
@@ -33,37 +33,6 @@
 namespace init {
 namespace {
 
-static constexpr const char* kLinkerMountPoint = "/bionic/bin/linker";
-static constexpr const char* kBootstrapLinkerPath = "/system/bin/bootstrap/linker";
-static constexpr const char* kRuntimeLinkerPath = "/apex/com.android.runtime/bin/linker";
-
-static constexpr const char* kBionicLibsMountPointDir = "/bionic/lib/";
-static constexpr const char* kBootstrapBionicLibsDir = "/system/lib/bootstrap/";
-static constexpr const char* kRuntimeBionicLibsDir = "/apex/com.android.runtime/lib/bionic/";
-
-static constexpr const char* kLinkerMountPoint64 = "/bionic/bin/linker64";
-static constexpr const char* kBootstrapLinkerPath64 = "/system/bin/bootstrap/linker64";
-static constexpr const char* kRuntimeLinkerPath64 = "/apex/com.android.runtime/bin/linker64";
-
-static constexpr const char* kBionicLibsMountPointDir64 = "/bionic/lib64/";
-static constexpr const char* kBootstrapBionicLibsDir64 = "/system/lib64/bootstrap/";
-static constexpr const char* kRuntimeBionicLibsDir64 = "/apex/com.android.runtime/lib64/bionic/";
-
-static const std::vector<std::string> kBionicLibFileNames = {"libc.so", "libm.so", "libdl.so"};
-
-static bool BindMount(const std::string& source, const std::string& mount_point,
-                      bool recursive = false) {
-    unsigned long mountflags = MS_BIND;
-    if (recursive) {
-        mountflags |= MS_REC;
-    }
-    if (mount(source.c_str(), mount_point.c_str(), nullptr, mountflags, nullptr) == -1) {
-        PLOG(ERROR) << "Could not bind-mount " << source << " to " << mount_point;
-        return false;
-    }
-    return true;
-}
-
 static bool MakeShared(const std::string& mount_point, bool recursive = false) {
     unsigned long mountflags = MS_SHARED;
     if (recursive) {
@@ -105,34 +74,6 @@
     return ret;
 }
 
-static bool BindMountBionic(const std::string& linker_source, const std::string& lib_dir_source,
-                            const std::string& linker_mount_point,
-                            const std::string& lib_mount_dir) {
-    if (access(linker_source.c_str(), F_OK) != 0) {
-        PLOG(INFO) << linker_source << " does not exist. skipping mounting bionic there.";
-        // This can happen for 64-bit bionic in 32-bit only device.
-        // It is okay to skip mounting the 64-bit bionic.
-        return true;
-    }
-    if (!BindMount(linker_source, linker_mount_point)) {
-        return false;
-    }
-    if (!MakePrivate(linker_mount_point)) {
-        return false;
-    }
-    for (const auto& libname : kBionicLibFileNames) {
-        std::string mount_point = lib_mount_dir + libname;
-        std::string source = lib_dir_source + libname;
-        if (!BindMount(source, mount_point)) {
-            return false;
-        }
-        if (!MakePrivate(mount_point)) {
-            return false;
-        }
-    }
-    return true;
-}
-
 static bool IsApexUpdatable() {
     static bool updatable = android::sysprop::ApexProperties::updatable().value_or(false);
     return updatable;
@@ -154,26 +95,7 @@
     // point to private.
     if (!MakeShared("/", true /*recursive*/)) return false;
 
-    // Since different files (bootstrap or runtime APEX) should be mounted to
-    // the same mount point paths (e.g. /bionic/bin/linker, /bionic/lib/libc.so,
-    // etc.) across the two mount namespaces, we create a private mount point at
-    // /bionic so that a mount event for the bootstrap bionic in the mount
-    // namespace for pre-apexd processes is not propagated to the other mount
-    // namespace for post-apexd process, and vice versa.
-    //
-    // Other mount points other than /bionic, however, are all still shared.
-    if (!BindMount("/bionic", "/bionic", true /*recursive*/)) return false;
-    if (!MakePrivate("/bionic")) return false;
-
-    // Bind-mount bootstrap bionic.
-    if (!BindMountBionic(kBootstrapLinkerPath, kBootstrapBionicLibsDir, kLinkerMountPoint,
-                         kBionicLibsMountPointDir))
-        return false;
-    if (!BindMountBionic(kBootstrapLinkerPath64, kBootstrapBionicLibsDir64, kLinkerMountPoint64,
-                         kBionicLibsMountPointDir64))
-        return false;
-
-    // /apex is also a private mountpoint to give different sets of APEXes for
+    // /apex is a private mountpoint to give different sets of APEXes for
     // the bootstrap and default mount namespaces. The processes running with
     // the bootstrap namespace get APEXes from the read-only partition.
     if (!(MakePrivate("/apex"))) return false;
@@ -181,12 +103,11 @@
     bootstrap_ns_fd.reset(OpenMountNamespace());
     bootstrap_ns_id = GetMountNamespaceId();
 
-    // When bionic is updatable via the runtime APEX, we create separate mount
+    // When APEXes are updatable (e.g. not-flattened), we create separate mount
     // namespaces for processes that are started before and after the APEX is
-    // activated by apexd. In the namespace for pre-apexd processes, the bionic
-    // from the /system partition (that we call bootstrap bionic) is
-    // bind-mounted. In the namespace for post-apexd processes, the bionic from
-    // the runtime APEX is bind-mounted.
+    // activated by apexd. In the namespace for pre-apexd processes, small
+    // number of essential APEXes (e.g. com.android.runtime) are activated.
+    // In the namespace for post-apexd processes, all APEXes are activated.
     bool success = true;
     if (IsApexUpdatable() && !IsRecoveryMode()) {
         // Creating a new namespace by cloning, saving, and switching back to
@@ -198,15 +119,6 @@
         default_ns_fd.reset(OpenMountNamespace());
         default_ns_id = GetMountNamespaceId();
 
-        // By this unmount, the bootstrap bionic are not mounted in the default
-        // mount namespace.
-        if (umount2("/bionic", MNT_DETACH) == -1) {
-            PLOG(ERROR) << "Cannot unmount /bionic";
-            // Don't return here. We have to switch back to the bootstrap
-            // namespace.
-            success = false;
-        }
-
         if (setns(bootstrap_ns_fd.get(), CLONE_NEWNS) == -1) {
             PLOG(ERROR) << "Cannot switch back to bootstrap mount namespace";
             return false;
@@ -237,28 +149,6 @@
     return true;
 }
 
-// TODO(jiyong): remove this when /system/lib/libc.so becomes
-// a symlink to /apex/com.android.runtime/lib/bionic/libc.so
-bool SetupRuntimeBionic() {
-    if (IsRecoveryMode()) {
-        // We don't have multiple namespaces in recovery mode
-        return true;
-    }
-    // Bind-mount bionic from the runtime APEX since it is now available. Note
-    // that in case of IsApexUpdatable() == false, these mounts are over the
-    // existing existing bind mounts for the bootstrap bionic, which effectively
-    // becomes hidden.
-    if (!BindMountBionic(kRuntimeLinkerPath, kRuntimeBionicLibsDir, kLinkerMountPoint,
-                         kBionicLibsMountPointDir))
-        return false;
-    if (!BindMountBionic(kRuntimeLinkerPath64, kRuntimeBionicLibsDir64, kLinkerMountPoint64,
-                         kBionicLibsMountPointDir64))
-        return false;
-
-    LOG(INFO) << "Runtime bionic is set up";
-    return true;
-}
-
 bool SwitchToBootstrapMountNamespaceIfNeeded() {
     if (IsRecoveryMode()) {
         // we don't have multiple namespaces in recovery mode
diff --git a/init/mount_namespace.h b/init/mount_namespace.h
index 4eef785..c41a449 100644
--- a/init/mount_namespace.h
+++ b/init/mount_namespace.h
@@ -20,7 +20,6 @@
 namespace init {
 
 bool SetupMountNamespaces();
-bool SetupRuntimeBionic();
 bool SwitchToDefaultMountNamespace();
 bool SwitchToBootstrapMountNamespaceIfNeeded();
 
diff --git a/rootdir/etc/ld.config.txt b/rootdir/etc/ld.config.txt
index 552d685..641a536 100644
--- a/rootdir/etc/ld.config.txt
+++ b/rootdir/etc/ld.config.txt
@@ -83,7 +83,7 @@
 namespace.default.permitted.paths += /%PRODUCT_SERVICES%/priv-app
 namespace.default.permitted.paths += /data
 namespace.default.permitted.paths += /mnt/expand
-namespace.default.permitted.paths += /bionic/${LIB}
+namespace.default.permitted.paths += /apex/com.android.runtime/${LIB}/bionic
 namespace.default.permitted.paths += /system/${LIB}/bootstrap
 
 namespace.default.asan.search.paths  = /data/asan/system/${LIB}
@@ -119,7 +119,7 @@
 namespace.default.asan.permitted.paths += /%PRODUCT_SERVICES%/app
 namespace.default.asan.permitted.paths += /%PRODUCT_SERVICES%/priv-app
 namespace.default.asan.permitted.paths += /mnt/expand
-namespace.default.asan.permitted.paths += /bionic/${LIB}
+namespace.default.asan.permitted.paths += /apex/com.android.runtime/${LIB}/bionic
 namespace.default.asan.permitted.paths += /system/${LIB}/bootstrap
 
 # Keep in sync with ld.config.txt in the com.android.runtime APEX.
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 3854c73..4c52596 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -578,8 +578,6 @@
 
     # Wait for apexd to finish activating APEXes before starting more processes.
     wait_for_prop apexd.status ready
-    # TODO(jiyong): remove setup_runtime_bionic
-    setup_runtime_bionic
     parse_apex_configs
 
     init_user0