Merge "Check and create data and obb dirs after starting zygote process." into sc-dev

core/java/android/os/storage/StorageManagerInternal.java

@@ -51,6 +51,11 @@ public abstract class StorageManagerInternal {
         void onReset(IVold vold);
     }
 
+    /**
+     * Return true if fuse is mounted.
+     */
+    public abstract boolean isFuseMounted(int userId);
+
     /**
      * Create storage directories if it does not exist.
      * Return true if the directories were setup correctly, otherwise false.

core/jni/com_android_internal_os_Zygote.cpp

@@ -184,6 +184,17 @@ static constexpr int PROCESS_PRIORITY_MIN = 19;
 /** The numeric value for the normal priority a process should have. */
 static constexpr int PROCESS_PRIORITY_DEFAULT = 0;
 
+/** Exponential back off parameters for storage dir check. */
+static constexpr unsigned int STORAGE_DIR_CHECK_RETRY_MULTIPLIER = 2;
+static constexpr unsigned int STORAGE_DIR_CHECK_INIT_INTERVAL_US = 50;
+static constexpr unsigned int STORAGE_DIR_CHECK_MAX_INTERVAL_US = 1000;
+/**
+ * Lower bound time we allow storage dir check to sleep.
+ * If it exceeds 2s, PROC_START_TIMEOUT_MSG will kill the starting app anyway,
+ * so it's fine to assume max retries is 5 mins.
+ */
+static constexpr int STORAGE_DIR_CHECK_TIMEOUT_US = 1000 * 60 * 5;
+
 /**
  * A helper class containing accounting information for USAPs.
  */
@@ -1458,6 +1469,31 @@ static void isolateJitProfile(JNIEnv* env, jobjectArray pkg_data_info_list,
   }
 }
 
+static void WaitUntilDirReady(const std::string& target, fail_fn_t fail_fn) {
+  unsigned int sleepIntervalUs = STORAGE_DIR_CHECK_INIT_INTERVAL_US;
+
+  // This is just an approximate value as it doesn't need to be very accurate.
+  unsigned int sleepTotalUs = 0;
+
+  const char* dir_path = target.c_str();
+  while (sleepTotalUs < STORAGE_DIR_CHECK_TIMEOUT_US) {
+    if (access(dir_path, F_OK) == 0) {
+      return;
+    }
+    // Failed, so we add exponential backoff and retry
+    usleep(sleepIntervalUs);
+    sleepTotalUs += sleepIntervalUs;
+    sleepIntervalUs = std::min<unsigned int>(
+        sleepIntervalUs * STORAGE_DIR_CHECK_RETRY_MULTIPLIER,
+        STORAGE_DIR_CHECK_MAX_INTERVAL_US);
+  }
+  // Last chance and get the latest errno if it fails.
+  if (access(dir_path, F_OK) == 0) {
+    return;
+  }
+  fail_fn(CREATE_ERROR("Error dir is not ready %s: %s", dir_path, strerror(errno)));
+}
+
 static void BindMountStorageToLowerFs(const userid_t user_id, const uid_t uid,
     const char* dir_name, const char* package, fail_fn_t fail_fn) {
     bool hasSdcardFs = IsSdcardfsUsed();
@@ -1468,6 +1504,10 @@ static void BindMountStorageToLowerFs(const userid_t user_id, const uid_t uid,
         source = StringPrintf("/mnt/pass_through/%d/emulated/%d/%s/%s", user_id, user_id, dir_name,
                               package);
     }
+
+  // Directory might be not ready, as prepareStorageDirs() is running asynchronously in ProcessList,
+  // so wait until dir is created.
+  WaitUntilDirReady(source, fail_fn);
   std::string target = StringPrintf("/storage/emulated/%d/%s/%s", user_id, dir_name, package);
 
   // As the parent is mounted as tmpfs, we need to create the target dir here.

services/core/java/com/android/server/StorageManagerService.java

@@ -4553,6 +4553,13 @@ class StorageManagerService extends IStorageManager.Stub
         private final List<StorageManagerInternal.ResetListener> mResetListeners =
                 new ArrayList<>();
 
+        @Override
+        public boolean isFuseMounted(int userId) {
+            synchronized (mLock) {
+                return mFuseMountedUser.contains(userId);
+            }
+        }
+
         /**
          * Check if fuse is running in target user, if it's running then setup its storage dirs.
          * Return true if storage dirs are mounted.

services/core/java/com/android/server/am/ProcessList.java

@@ -2315,11 +2315,12 @@ public final class ProcessList {
             StorageManagerInternal storageManagerInternal = LocalServices.getService(
                     StorageManagerInternal.class);
             if (needsStorageDataIsolation(storageManagerInternal, app)) {
-                bindMountAppStorageDirs = true;
-                if (pkgDataInfoMap == null ||
-                        !storageManagerInternal.prepareStorageDirs(userId, pkgDataInfoMap.keySet(),
-                        app.processName)) {
-                    // Cannot prepare Android/app and Android/obb directory or inode == 0,
+                // We will run prepareStorageDirs() after we trigger zygote fork, so it won't
+                // slow down app starting speed as those dirs might not be cached.
+                if (pkgDataInfoMap != null && storageManagerInternal.isFuseMounted(userId)) {
+                    bindMountAppStorageDirs = true;
+                } else {
+                    // Fuse is not mounted or inode == 0,
                     // so we won't mount it in zygote, but resume the mount after unlocking device.
                     app.setBindMountPending(true);
                     bindMountAppStorageDirs = false;
@@ -2367,6 +2368,13 @@ public final class ProcessList {
                         allowlistedAppDataInfoMap, bindMountAppsData, bindMountAppStorageDirs,
                         new String[]{PROC_START_SEQ_IDENT + app.getStartSeq()});
             }
+            // This runs after Process.start() as this method may block app process starting time
+            // if dir is not cached. Running this method after Process.start() can make it
+            // cache the dir asynchronously, so zygote can use it without waiting for it.
+            if (bindMountAppStorageDirs) {
+                storageManagerInternal.prepareStorageDirs(userId, pkgDataInfoMap.keySet(),
+                        app.processName);
+            }
             checkSlow(startTime, "startProcess: returned from zygote!");
             return startResult;
         } finally {