recovery: add --fsck_unshare_blocks option for adb remount

Allow "adb remount" on deduplicated filesystems to reboot into recovery
and run e2fsck to undo deduplication. The e2fsck binary is copied from
the system partition into tmpfs, and the system partition is unmounted
so e2fsck can run safely.

Bug: 64109868
Test: recovery with --fsck_unshare_blocks; adb remount
Change-Id: I7558749b018b58f3c4339e51a95831dbd5be1ae3

Android.mk

@@ -132,6 +132,7 @@ include $(CLEAR_VARS)
 
 LOCAL_SRC_FILES := \
     adb_install.cpp \
+    fsck_unshare_blocks.cpp \
     fuse_sdcard_provider.cpp \
     install.cpp \
     recovery.cpp \
@@ -192,6 +193,13 @@ LOCAL_REQUIRED_MODULES += \
 endif
 endif
 
+# e2fsck is needed for adb remount -R.
+ifeq ($(BOARD_EXT4_SHARE_DUP_BLOCKS),true)
+ifneq (,$(filter userdebug eng,$(TARGET_BUILD_VARIANT)))
+LOCAL_REQUIRED_MODULES += e2fsck_static
+endif
+endif
+
 ifeq ($(BOARD_CACHEIMAGE_PARTITION_SIZE),)
 LOCAL_REQUIRED_MODULES += \
     recovery-persist \

fsck_unshare_blocks.cpp

@@ -0,0 +1,163 @@
+/*
+ * 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 "fsck_unshare_blocks.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <spawn.h>
+#include <string.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include <algorithm>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <android-base/logging.h>
+#include <android-base/properties.h>
+#include <android-base/unique_fd.h>
+#include <fstab/fstab.h>
+
+#include "roots.h"
+
+static constexpr const char* SYSTEM_E2FSCK_BIN = "/system/bin/e2fsck_static";
+static constexpr const char* TMP_E2FSCK_BIN = "/tmp/e2fsck.bin";
+
+static bool copy_file(const char* source, const char* dest) {
+  android::base::unique_fd source_fd(open(source, O_RDONLY));
+  if (source_fd < 0) {
+    PLOG(ERROR) << "open %s failed" << source;
+    return false;
+  }
+
+  android::base::unique_fd dest_fd(open(dest, O_CREAT | O_WRONLY, S_IRWXU));
+  if (dest_fd < 0) {
+    PLOG(ERROR) << "open %s failed" << dest;
+    return false;
+  }
+
+  for (;;) {
+    char buf[4096];
+    ssize_t rv = read(source_fd, buf, sizeof(buf));
+    if (rv < 0) {
+      PLOG(ERROR) << "read failed";
+      return false;
+    }
+    if (rv == 0) {
+      break;
+    }
+    if (write(dest_fd, buf, rv) != rv) {
+      PLOG(ERROR) << "write failed";
+      return false;
+    }
+  }
+  return true;
+}
+
+static bool run_e2fsck(const std::string& partition) {
+  Volume* volume = volume_for_mount_point(partition);
+  if (!volume) {
+    LOG(INFO) << "No fstab entry for " << partition << ", skipping.";
+    return true;
+  }
+
+  LOG(INFO) << "Running e2fsck on device " << volume->blk_device;
+
+  std::vector<std::string> args = { TMP_E2FSCK_BIN, "-p", "-E", "unshare_blocks",
+                                    volume->blk_device };
+  std::vector<char*> argv(args.size());
+  std::transform(args.cbegin(), args.cend(), argv.begin(),
+                 [](const std::string& arg) { return const_cast<char*>(arg.c_str()); });
+  argv.push_back(nullptr);
+
+  pid_t child;
+  char* env[] = { nullptr };
+  if (posix_spawn(&child, argv[0], nullptr, nullptr, argv.data(), env)) {
+    PLOG(ERROR) << "posix_spawn failed";
+    return false;
+  }
+
+  int status = 0;
+  int ret = TEMP_FAILURE_RETRY(waitpid(child, &status, 0));
+  if (ret < 0) {
+    PLOG(ERROR) << "waitpid failed";
+    return false;
+  }
+  if (!WIFEXITED(status)) {
+    LOG(ERROR) << "e2fsck exited abnormally: " << status;
+    return false;
+  }
+  int return_code = WEXITSTATUS(status);
+  if (return_code >= 8) {
+    LOG(ERROR) << "e2fsck could not unshare blocks: " << return_code;
+    return false;
+  }
+
+  LOG(INFO) << "Successfully unshared blocks on " << partition;
+  return true;
+}
+
+static const char* get_system_root() {
+  if (android::base::GetBoolProperty("ro.build.system_root_image", false)) {
+    return "/system_root";
+  } else {
+    return "/system";
+  }
+}
+
+bool do_fsck_unshare_blocks() {
+  // List of partitions we will try to e2fsck -E unshare_blocks.
+  std::vector<std::string> partitions = { "/odm", "/oem", "/product", "/vendor" };
+
+  // Temporarily mount system so we can copy e2fsck_static.
+  bool mounted = false;
+  if (android::base::GetBoolProperty("ro.build.system_root_image", false)) {
+    mounted = ensure_path_mounted_at("/", "/system_root") != -1;
+    partitions.push_back("/");
+  } else {
+    mounted = ensure_path_mounted("/system") != -1;
+    partitions.push_back("/system");
+  }
+  if (!mounted) {
+    LOG(ERROR) << "Failed to mount system image.";
+    return false;
+  }
+  if (!copy_file(SYSTEM_E2FSCK_BIN, TMP_E2FSCK_BIN)) {
+    LOG(ERROR) << "Could not copy e2fsck to /tmp.";
+    return false;
+  }
+  if (umount(get_system_root()) < 0) {
+    PLOG(ERROR) << "umount failed";
+    return false;
+  }
+
+  bool ok = true;
+  for (const auto& partition : partitions) {
+    ok &= run_e2fsck(partition);
+  }
+
+  if (ok) {
+    LOG(INFO) << "Finished running e2fsck.";
+  } else {
+    LOG(ERROR) << "Finished running e2fsck, but not all partitions succceeded.";
+  }
+  return ok;
+}

fsck_unshare_blocks.h

@@ -0,0 +1,22 @@
+/*
+ * 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.
+ */
+
+#ifndef _FILESYSTEM_CMDS_H
+#define _FILESYSTEM_CMDS_H
+
+bool do_fsck_unshare_blocks();
+
+#endif  // _FILESYSTEM_CMDS_H

recovery.cpp

@@ -55,6 +55,7 @@
 #include "adb_install.h"
 #include "common.h"
 #include "device.h"
+#include "fsck_unshare_blocks.h"
 #include "fuse_sdcard_provider.h"
 #include "fuse_sideload.h"
 #include "install.h"
@@ -969,6 +970,7 @@ Device::BuiltinAction start_recovery(Device* device, const std::vector<std::stri
                  [](const std::string& arg) { return const_cast<char*>(arg.c_str()); });
 
   static constexpr struct option OPTIONS[] = {
+    { "fsck_unshare_blocks", no_argument, nullptr, 0 },
     { "just_exit", no_argument, nullptr, 'x' },
     { "locale", required_argument, nullptr, 0 },
     { "prompt_and_wipe_data", no_argument, nullptr, 0 },
@@ -997,6 +999,7 @@ Device::BuiltinAction start_recovery(Device* device, const std::vector<std::stri
   bool sideload_auto_reboot = false;
   bool just_exit = false;
   bool shutdown_after = false;
+  bool fsck_unshare_blocks = false;
   int retry_count = 0;
   bool security_update = false;
   std::string locale;
@@ -1014,7 +1017,9 @@ Device::BuiltinAction start_recovery(Device* device, const std::vector<std::stri
         break;
       case 0: {
         std::string option = OPTIONS[option_index].name;
-        if (option == "locale") {
+        if (option == "fsck_unshare_blocks") {
+          fsck_unshare_blocks = true;
+        } else if (option == "locale") {
           // Handled in recovery_main.cpp
         } else if (option == "prompt_and_wipe_data") {
           should_prompt_and_wipe_data = true;
@@ -1181,6 +1186,10 @@ Device::BuiltinAction start_recovery(Device* device, const std::vector<std::stri
     if (sideload_auto_reboot) {
       ui->Print("Rebooting automatically.\n");
     }
+  } else if (fsck_unshare_blocks) {
+    if (!do_fsck_unshare_blocks()) {
+      status = INSTALL_ERROR;
+    }
   } else if (!just_exit) {
     // If this is an eng or userdebug build, automatically turn on the text display if no command
     // is specified. Note that this should be called before setting the background to avoid