Pass bind mount storage data decision from java to zygote

Before we used store dirty data in system property to record
if FUSE for a user is mounted, and zygote uses it to determine
if storage mount is needed. It introduces performance issues and
not reliable.

This CL does the following changes:

- System server determines if storage dirs mount are needed, and store
the record inside system server.

- It passes the verdict to zygote so zygote just need to follow the
input.

- When emulated storage is mounted / unmounted, it will record if
FUSE for that user is ready to use, and will be used for determining
if storage dirs mount are needed when a new process starts.

- After emulated storage is mounted, it will create an async thread
to remount all storage dirs for existing app processes. As we have a
record of pids that storage dirs are not mounted yet, we can use it
directly without scanning the whole /proc in vold.

Bug: 149548518
Test: After flag is enabled, AdoptableHostTest still pass.
Change-Id: Ic99d027d42b2b9a1c7fd03070b36c44882c6e7c5

4 files changed, 27 insertions, 7 deletions

diff --git a/core/java/android/app/ActivityManagerInternal.java b/core/java/android/app/ActivityManagerInternal.java
index ec110435d95c..489a0de0518e 100644
--- a/core/java/android/app/ActivityManagerInternal.java
+++ b/core/java/android/app/ActivityManagerInternal.java
@@ -34,6 +34,7 @@ import android.os.TransactionTooLargeException;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
 
 /**
  * Activity manager local system service interface.
@@ -124,6 +125,12 @@ public abstract class ActivityManagerInternal {
     public abstract int getUidProcessState(int uid);
 
     /**
+     * Get a map of pid and package name that process of that pid Android/data and Android/obb
+     * directory is not mounted to lowerfs.
+     */
+    public abstract Map<Integer, String> getProcessesWithPendingBindMounts(int userId);
+
+    /**
      * @return {@code true} if system is ready, {@code false} otherwise.
      */
     public abstract boolean isSystemReady();
diff --git a/core/java/android/os/Process.java b/core/java/android/os/Process.java
index d7af1b9faa97..a557bd994c13 100644
--- a/core/java/android/os/Process.java
+++ b/core/java/android/os/Process.java
@@ -607,6 +607,7 @@ public class Process {
      *                             started.
      * @param pkgDataInfoMap Map from related package names to private data directory
      *                       volume UUID and inode number.
+     * @param bindMountAppStorageDirs whether zygote needs to mount Android/obb and Android/data.
      * @param zygoteArgs Additional arguments to supply to the zygote process.
      * @return An object that describes the result of the attempt to start the process.
      * @throws RuntimeException on fatal start failure
@@ -630,12 +631,13 @@ public class Process {
                                            @Nullable long[] disabledCompatChanges,
                                            @Nullable Map<String, Pair<String, Long>>
                                                    pkgDataInfoMap,
+                                           boolean bindMountAppStorageDirs,
                                            @Nullable String[] zygoteArgs) {
         return ZYGOTE_PROCESS.start(processClass, niceName, uid, gid, gids,
                     runtimeFlags, mountExternal, targetSdkVersion, seInfo,
                     abi, instructionSet, appDataDir, invokeWith, packageName,
                     zygotePolicyFlags, isTopApp, disabledCompatChanges,
-                    pkgDataInfoMap, zygoteArgs);
+                    pkgDataInfoMap, bindMountAppStorageDirs, zygoteArgs);
     }
 
     /** @hide */
@@ -659,7 +661,7 @@ public class Process {
                     runtimeFlags, mountExternal, targetSdkVersion, seInfo,
                     abi, instructionSet, appDataDir, invokeWith, packageName,
                     /*zygotePolicyFlags=*/ ZYGOTE_POLICY_FLAG_EMPTY, /*isTopApp=*/ false,
-                disabledCompatChanges, /* pkgDataInfoMap */ null, zygoteArgs);
+                disabledCompatChanges, /* pkgDataInfoMap */ null, false, zygoteArgs);
     }
 
     /**
diff --git a/core/java/android/os/ZygoteProcess.java b/core/java/android/os/ZygoteProcess.java
index 34cec061edcd..5f3f14facd75 100644
--- a/core/java/android/os/ZygoteProcess.java
+++ b/core/java/android/os/ZygoteProcess.java
@@ -333,6 +333,7 @@ public class ZygoteProcess {
      *                             started.
      * @param pkgDataInfoMap Map from related package names to private data directory
      *                       volume UUID and inode number.
+     * @param bindMountAppStorageDirs whether zygote needs to mount Android/obb and Android/data.
      *
      * @param zygoteArgs Additional arguments to supply to the Zygote process.
      * @return An object that describes the result of the attempt to start the process.
@@ -354,6 +355,7 @@ public class ZygoteProcess {
                                                   @Nullable long[] disabledCompatChanges,
                                                   @Nullable Map<String, Pair<String, Long>>
                                                           pkgDataInfoMap,
+                                                  boolean bindMountAppStorageDirs,
                                                   @Nullable String[] zygoteArgs) {
         // TODO (chriswailes): Is there a better place to check this value?
         if (fetchUsapPoolEnabledPropWithMinInterval()) {
@@ -365,7 +367,7 @@ public class ZygoteProcess {
                     runtimeFlags, mountExternal, targetSdkVersion, seInfo,
                     abi, instructionSet, appDataDir, invokeWith, /*startChildZygote=*/ false,
                     packageName, zygotePolicyFlags, isTopApp, disabledCompatChanges,
-                    pkgDataInfoMap, zygoteArgs);
+                    pkgDataInfoMap, bindMountAppStorageDirs, zygoteArgs);
         } catch (ZygoteStartFailedEx ex) {
             Log.e(LOG_TAG,
                     "Starting VM process through Zygote failed");
@@ -606,6 +608,7 @@ public class ZygoteProcess {
      * @param disabledCompatChanges a list of disabled compat changes for the process being started.
      * @param pkgDataInfoMap Map from related package names to private data directory volume UUID
      *                       and inode number.
+     * @param bindMountAppStorageDirs whether zygote needs to mount Android/obb and Android/data.
      * @param extraArgs Additional arguments to supply to the zygote process.
      * @return An object that describes the result of the attempt to start the process.
      * @throws ZygoteStartFailedEx if process start failed for any reason
@@ -628,6 +631,7 @@ public class ZygoteProcess {
                                                       @Nullable long[] disabledCompatChanges,
                                                       @Nullable Map<String, Pair<String, Long>>
                                                               pkgDataInfoMap,
+                                                      boolean bindMountAppStorageDirs,
                                                       @Nullable String[] extraArgs)
                                                       throws ZygoteStartFailedEx {
         ArrayList<String> argsForZygote = new ArrayList<>();
@@ -725,6 +729,10 @@ public class ZygoteProcess {
             argsForZygote.add(sb.toString());
         }
 
+        if (bindMountAppStorageDirs) {
+            argsForZygote.add(Zygote.BIND_MOUNT_APP_STORAGE_DIRS);
+        }
+
         if (disabledCompatChanges != null && disabledCompatChanges.length > 0) {
             StringBuilder sb = new StringBuilder();
             sb.append("--disabled-compat-changes=");
@@ -1282,7 +1290,9 @@ public class ZygoteProcess {
                     abi, instructionSet, null /* appDataDir */, null /* invokeWith */,
                     true /* startChildZygote */, null /* packageName */,
                     ZYGOTE_POLICY_FLAG_SYSTEM_PROCESS /* zygotePolicyFlags */, false /* isTopApp */,
-                    null /* disabledCompatChanges */, null /* pkgDataInfoMap */, extraArgs);
+                    null /* disabledCompatChanges */, null /* pkgDataInfoMap */,
+                    /* bindMountAppStorageDirs */ false, extraArgs);
+
         } catch (ZygoteStartFailedEx ex) {
             throw new RuntimeException("Starting child-zygote through Zygote failed", ex);
         }
diff --git a/core/java/android/os/storage/StorageManagerInternal.java b/core/java/android/os/storage/StorageManagerInternal.java
index a2def7fff2d2..f43a2523b5b3 100644
--- a/core/java/android/os/storage/StorageManagerInternal.java
+++ b/core/java/android/os/storage/StorageManagerInternal.java
@@ -100,10 +100,11 @@ public abstract class StorageManagerInternal {
     }
 
     /**
-     * Check if fuse is running in target user, if it's running then setup its obb directories.
-     * TODO: System server should store a list of active pids that obb is not mounted and use it.
+     * Create storage directories if it does not exist.
+     * Return true if the directories were setup correctly, otherwise false.
      */
-    public abstract void prepareObbDirs(int userId, Set<String> packageList, String processName);
+    public abstract boolean prepareStorageDirs(int userId, Set<String> packageList,
+            String processName);
 
     /**
      * Add a listener to listen to reset event in StorageManagerService.