Merge "Allow apps to process ProxyFDCallback asynchrnously." into oc-dev

am: 76c32a35a9

Change-Id: I9e17751f706f9e0869eefafb77bf1704335f5116

api/current.txt

@@ -31898,6 +31898,7 @@ package android.os.storage {
     method public boolean isObbMounted(java.lang.String);
     method public boolean mountObb(java.lang.String, java.lang.String, android.os.storage.OnObbStateChangeListener);
     method public android.os.ParcelFileDescriptor openProxyFileDescriptor(int, android.os.ProxyFileDescriptorCallback) throws java.io.IOException;
+    method public android.os.ParcelFileDescriptor openProxyFileDescriptor(int, android.os.ProxyFileDescriptorCallback, android.os.Handler) throws java.io.IOException;
     method public void setCacheBehaviorGroup(java.io.File, boolean) throws java.io.IOException;
     method public void setCacheBehaviorTombstone(java.io.File, boolean) throws java.io.IOException;
     method public boolean unmountObb(java.lang.String, boolean, android.os.storage.OnObbStateChangeListener);

api/system-current.txt

@@ -34731,6 +34731,7 @@ package android.os.storage {
     method public boolean isObbMounted(java.lang.String);
     method public boolean mountObb(java.lang.String, java.lang.String, android.os.storage.OnObbStateChangeListener);
     method public android.os.ParcelFileDescriptor openProxyFileDescriptor(int, android.os.ProxyFileDescriptorCallback) throws java.io.IOException;
+    method public android.os.ParcelFileDescriptor openProxyFileDescriptor(int, android.os.ProxyFileDescriptorCallback, android.os.Handler) throws java.io.IOException;
     method public void setCacheBehaviorGroup(java.io.File, boolean) throws java.io.IOException;
     method public void setCacheBehaviorTombstone(java.io.File, boolean) throws java.io.IOException;
     method public boolean unmountObb(java.lang.String, boolean, android.os.storage.OnObbStateChangeListener);

api/test-current.txt

@@ -32035,6 +32035,7 @@ package android.os.storage {
     method public boolean isObbMounted(java.lang.String);
     method public boolean mountObb(java.lang.String, java.lang.String, android.os.storage.OnObbStateChangeListener);
     method public android.os.ParcelFileDescriptor openProxyFileDescriptor(int, android.os.ProxyFileDescriptorCallback) throws java.io.IOException;
+    method public android.os.ParcelFileDescriptor openProxyFileDescriptor(int, android.os.ProxyFileDescriptorCallback, android.os.Handler) throws java.io.IOException;
     method public void setCacheBehaviorGroup(java.io.File, boolean) throws java.io.IOException;
     method public void setCacheBehaviorTombstone(java.io.File, boolean) throws java.io.IOException;
     method public boolean unmountObb(java.lang.String, boolean, android.os.storage.OnObbStateChangeListener);

core/java/android/os/storage/StorageManager.java

@@ -59,6 +59,8 @@ import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.logging.MetricsLogger;
 import com.android.internal.os.AppFuseMount;
 import com.android.internal.os.FuseAppLoop;
+import com.android.internal.os.FuseAppLoop.UnmountedException;
+import com.android.internal.os.FuseUnavailableMountException;
 import com.android.internal.os.RoSystemProperties;
 import com.android.internal.os.SomeArgs;
 import com.android.internal.util.Preconditions;
@@ -82,6 +84,7 @@ import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.atomic.AtomicInteger;
+import libcore.io.IoUtils;
 
 /**
  * StorageManager is the interface to the systems storage service. The storage
@@ -1390,53 +1393,52 @@ public class StorageManager {
     /** {@hide} */
     @VisibleForTesting
     public @NonNull ParcelFileDescriptor openProxyFileDescriptor(
-            int mode, ProxyFileDescriptorCallback callback, ThreadFactory factory)
+            int mode, ProxyFileDescriptorCallback callback, Handler handler, ThreadFactory factory)
                     throws IOException {
         MetricsLogger.count(mContext, "storage_open_proxy_file_descriptor", 1);
         // Retry is needed because the mount point mFuseAppLoop is using may be unmounted before
         // invoking StorageManagerService#openProxyFileDescriptor. In this case, we need to re-mount
         // the bridge by calling mountProxyFileDescriptorBridge.
-        int retry = 3;
+        while (true) {
-        while (retry-- > 0) {
             try {
                 synchronized (mFuseAppLoopLock) {
+                    boolean newlyCreated = false;
                     if (mFuseAppLoop == null) {
                         final AppFuseMount mount = mStorageManager.mountProxyFileDescriptorBridge();
                         if (mount == null) {
-                            Log.e(TAG, "Failed to open proxy file bridge.");
+                            throw new IOException("Failed to mount proxy bridge");
-                            throw new IOException("Failed to open proxy file bridge.");
                         }
-                        mFuseAppLoop = FuseAppLoop.open(mount.mountPointId, mount.fd, factory);
+                        mFuseAppLoop = new FuseAppLoop(mount.mountPointId, mount.fd, factory);
+                        newlyCreated = true;
+                    }
+                    if (handler == null) {
+                        handler = new Handler(Looper.getMainLooper());
                     }
-
                     try {
-                        final int fileId = mFuseAppLoop.registerCallback(callback);
+                        final int fileId = mFuseAppLoop.registerCallback(callback, handler);
-                        final ParcelFileDescriptor pfd =
+                        final ParcelFileDescriptor pfd = mStorageManager.openProxyFileDescriptor(
-                                mStorageManager.openProxyFileDescriptor(
                                 mFuseAppLoop.getMountPointId(), fileId, mode);
-                        if (pfd != null) {
+                        if (pfd == null) {
-                            return pfd;
-                        }
-                        // Probably the bridge is being unmounted but mFuseAppLoop has not been
-                        // noticed it yet.
                             mFuseAppLoop.unregisterCallback(fileId);
-                    } catch (FuseAppLoop.UnmountedException error) {
+                            throw new FuseUnavailableMountException(
-                        Log.d(TAG, "mFuseAppLoop has been already unmounted.");
+                                    mFuseAppLoop.getMountPointId());
+                        }
+                        return pfd;
+                    } catch (FuseUnavailableMountException exception) {
+                        // The bridge is being unmounted. Tried to recreate it unless the bridge was
+                        // just created.
+                        if (newlyCreated) {
+                            throw new IOException(exception);
+                        }
                         mFuseAppLoop = null;
                         continue;
                     }
                 }
-                try {
-                    Thread.sleep(100);
-                } catch (InterruptedException e) {
-                    break;
-                }
             } catch (RemoteException e) {
-                e.rethrowFromSystemServer();
+                // Cannot recover from remote exception.
+                throw new IOException(e);
             }
         }
-
-        throw new IOException("Failed to mount bridge.");
     }
 
     /**
@@ -1448,16 +1450,37 @@ public class StorageManager {
      *     {@link ParcelFileDescriptor#MODE_WRITE_ONLY}, or
      *     {@link ParcelFileDescriptor#MODE_READ_WRITE}
      * @param callback Callback to process file operation requests issued on returned file
-     *     descriptor. The callback is invoked on a thread managed by the framework.
+     *     descriptor.
      * @return Seekable ParcelFileDescriptor.
      * @throws IOException
      */
     public @NonNull ParcelFileDescriptor openProxyFileDescriptor(
             int mode, ProxyFileDescriptorCallback callback)
                     throws IOException {
-        return openProxyFileDescriptor(mode, callback, null);
+        return openProxyFileDescriptor(mode, callback, null, null);
     }
 
+    /**
+     * Opens seekable ParcelFileDescriptor that routes file operation requests to
+     * ProxyFileDescriptorCallback.
+     *
+     * @param mode The desired access mode, must be one of
+     *     {@link ParcelFileDescriptor#MODE_READ_ONLY},
+     *     {@link ParcelFileDescriptor#MODE_WRITE_ONLY}, or
+     *     {@link ParcelFileDescriptor#MODE_READ_WRITE}
+     * @param callback Callback to process file operation requests issued on returned file
+     *     descriptor.
+     * @param handler Handler that invokes callback methods.
+     * @return Seekable ParcelFileDescriptor.
+     * @throws IOException
+     */
+    public @NonNull ParcelFileDescriptor openProxyFileDescriptor(
+            int mode, ProxyFileDescriptorCallback callback, Handler handler)
+                    throws IOException {
+        return openProxyFileDescriptor(mode, callback, handler, null);
+    }
+
+
     /** {@hide} */
     @VisibleForTesting
     public int getProxyFileDescriptorMountPointId() {

core/java/com/android/internal/os/FuseAppLoop.java

@@ -19,16 +19,16 @@ package com.android.internal.os;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.os.ProxyFileDescriptorCallback;
+import android.os.Handler;
 import android.os.ParcelFileDescriptor;
 import android.system.ErrnoException;
 import android.system.OsConstants;
 import android.util.Log;
 import android.util.SparseArray;
 import com.android.internal.annotations.GuardedBy;
-import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.util.Preconditions;
-
+import java.util.HashMap;
-import java.io.IOException;
+import java.util.Map;
 import java.util.concurrent.ThreadFactory;
 
 public class FuseAppLoop {
@@ -42,14 +42,21 @@ public class FuseAppLoop {
             return new Thread(r, TAG);
         }
     };
+    private static final int FUSE_OK = 0;
 
     private final Object mLock = new Object();
     private final int mMountPointId;
     private final Thread mThread;
+    private final Handler mDefaultHandler;
+
+    private static final int CMD_FSYNC = 1;
 
     @GuardedBy("mLock")
     private final SparseArray<CallbackEntry> mCallbackMap = new SparseArray<>();
 
+    @GuardedBy("mLock")
+    private final BytesMap mBytesMap = new BytesMap();
+
     /**
      * Sequential number can be used as file name and inode in AppFuse.
      * 0 is regarded as an error, 1 is mount point. So we start the number from 2.
@@ -57,38 +64,40 @@ public class FuseAppLoop {
     @GuardedBy("mLock")
     private int mNextInode = MIN_INODE;
 
-    private FuseAppLoop(
+    @GuardedBy("mLock")
+    private long mInstance;
+
+    public FuseAppLoop(
             int mountPointId, @NonNull ParcelFileDescriptor fd, @Nullable ThreadFactory factory) {
         mMountPointId = mountPointId;
-        final int rawFd = fd.detachFd();
         if (factory == null) {
             factory = sDefaultThreadFactory;
         }
-        mThread = factory.newThread(new Runnable() {
+        mInstance = native_new(fd.detachFd());
-            @Override
+        mThread = factory.newThread(() -> {
-            public void run() {
+            native_start(mInstance);
-                // rawFd is closed by native_start_loop. Java code does not need to close it.
+            synchronized (mLock) {
-                native_start_loop(rawFd);
+                native_delete(mInstance);
+                mInstance = 0;
+                mBytesMap.clear();
             }
         });
+        mThread.start();
+        mDefaultHandler = null;
     }
 
-    public static @NonNull FuseAppLoop open(int mountPointId, @NonNull ParcelFileDescriptor fd,
+    public int registerCallback(@NonNull ProxyFileDescriptorCallback callback,
-            @Nullable ThreadFactory factory) {
+            @NonNull Handler handler) throws FuseUnavailableMountException {
-        Preconditions.checkNotNull(fd);
-        final FuseAppLoop loop = new FuseAppLoop(mountPointId, fd, factory);
-        loop.mThread.start();
-        return loop;
-    }
-
-    public int registerCallback(@NonNull ProxyFileDescriptorCallback callback)
-            throws UnmountedException, IOException {
-        if (mThread.getState() == Thread.State.TERMINATED) {
-            throw new UnmountedException();
-        }
         synchronized (mLock) {
-            if (mCallbackMap.size() >= Integer.MAX_VALUE - MIN_INODE) {
+            Preconditions.checkNotNull(callback);
-                throw new IOException("Too many opened files.");
+            Preconditions.checkNotNull(handler);
+            Preconditions.checkState(
+                    mCallbackMap.size() < Integer.MAX_VALUE - MIN_INODE, "Too many opened files.");
+            Preconditions.checkArgument(
+                    Thread.currentThread().getId() != handler.getLooper().getThread().getId(),
+                    "Handler must be different from the current thread");
+            if (mInstance == 0) {
+                throw new FuseUnavailableMountException(mMountPointId);
             }
             int id;
             while (true) {
@@ -101,118 +110,171 @@ public class FuseAppLoop {
                     break;
                 }
             }
-            mCallbackMap.put(id, new CallbackEntry(callback));
+            mCallbackMap.put(id, new CallbackEntry(callback, handler));
             return id;
         }
     }
 
     public void unregisterCallback(int id) {
+        synchronized (mLock) {
             mCallbackMap.remove(id);
         }
+    }
 
     public int getMountPointId() {
         return mMountPointId;
     }
 
-    private CallbackEntry getCallbackEntryOrThrowLocked(long inode) throws ErrnoException {
+    // Defined in fuse.h
-        final CallbackEntry entry = mCallbackMap.get(checkInode(inode));
+    private static final int FUSE_LOOKUP = 1;
-        if (entry != null) {
+    private static final int FUSE_GETATTR = 3;
-            return entry;
+    private static final int FUSE_OPEN = 14;
-        } else {
+    private static final int FUSE_READ = 15;
-            throw new ErrnoException("getCallbackEntry", OsConstants.ENOENT);
+    private static final int FUSE_WRITE = 16;
-        }
+    private static final int FUSE_RELEASE = 18;
-    }
+    private static final int FUSE_FSYNC = 20;
+
+    // Defined in FuseBuffer.h
+    private static final int FUSE_MAX_WRITE = 256 * 1024;
 
     // Called by JNI.
     @SuppressWarnings("unused")
-    private long onGetSize(long inode) {
+    private void onCommand(int command, long unique, long inode, long offset, int size,
+            byte[] data) {
         synchronized(mLock) {
             try {
-                return getCallbackEntryOrThrowLocked(inode).callback.onGetSize();
+                final CallbackEntry entry = getCallbackEntryOrThrowLocked(inode);
-            } catch (ErrnoException exp) {
+                entry.postRunnable(() -> {
-                return getError(exp);
+                    try {
+                        switch (command) {
+                            case FUSE_LOOKUP: {
+                                final long fileSize = entry.callback.onGetSize();
+                                synchronized (mLock) {
+                                    if (mInstance != 0) {
+                                        native_replyLookup(mInstance, unique, inode, fileSize);
+                                    }
+                                }
+                                break;
+                            }
+                            case FUSE_GETATTR: {
+                                final long fileSize = entry.callback.onGetSize();
+                                synchronized (mLock) {
+                                    if (mInstance != 0) {
+                                        native_replyGetAttr(mInstance, unique, inode, fileSize);
+                                    }
+                                }
+                                break;
+                            }
+                            case FUSE_READ:
+                                final int readSize = entry.callback.onRead(offset, size, data);
+                                synchronized (mLock) {
+                                    if (mInstance != 0) {
+                                        native_replyRead(mInstance, unique, readSize, data);
+                                    }
+                                }
+                                break;
+                            case FUSE_WRITE:
+                                final int writeSize = entry.callback.onWrite(offset, size, data);
+                                synchronized (mLock) {
+                                    if (mInstance != 0) {
+                                        native_replyWrite(mInstance, unique, writeSize);
+                                    }
+                                }
+                                break;
+                            case FUSE_FSYNC:
+                                entry.callback.onFsync();
+                                synchronized (mLock) {
+                                    if (mInstance != 0) {
+                                        native_replySimple(mInstance, unique, FUSE_OK);
+                                    }
+                                }
+                                break;
+                            case FUSE_RELEASE:
+                                entry.callback.onRelease();
+                                synchronized (mLock) {
+                                    if (mInstance != 0) {
+                                        native_replySimple(mInstance, unique, FUSE_OK);
+                                    }
+                                    mBytesMap.stopUsing(entry.getThreadId());
+                                }
+                                break;
+                            default:
+                                throw new IllegalArgumentException(
+                                        "Unknown FUSE command: " + command);
+                        }
+                    } catch (Exception error) {
+                        Log.e(TAG, "", error);
+                        replySimple(unique, getError(error));
+                    }
+                });
+            } catch (ErrnoException error) {
+                Log.e(TAG, "", error);
+                replySimpleLocked(unique, getError(error));
             }
         }
     }
 
     // Called by JNI.
     @SuppressWarnings("unused")
-    private int onOpen(long inode) {
+    private byte[] onOpen(long unique, long inode) {
         synchronized (mLock) {
             try {
                 final CallbackEntry entry = getCallbackEntryOrThrowLocked(inode);
                 if (entry.opened) {
                     throw new ErrnoException("onOpen", OsConstants.EMFILE);
                 }
+                if (mInstance != 0) {
+                    native_replyOpen(mInstance, unique, /* fh */ inode);
                     entry.opened = true;
-                // Use inode as file handle. It's OK because AppFuse does not allow to open the same
+                    return mBytesMap.startUsing(entry.getThreadId());
-                // file twice.
-                return (int) inode;
-            } catch (ErrnoException exp) {
-                return getError(exp);
                 }
+            } catch (ErrnoException error) {
+                replySimpleLocked(unique, getError(error));
+            }
+            return null;
         }
     }
 
-    // Called by JNI.
+    private static int getError(@NonNull Exception error) {
-    @SuppressWarnings("unused")
+        if (error instanceof ErrnoException) {
-    private int onFsync(long inode) {
+            final int errno = ((ErrnoException) error).errno;
+            if (errno != OsConstants.ENOSYS) {
+                return -errno;
+            }
+        }
+        return -OsConstants.EBADF;
+    }
+
+    private CallbackEntry getCallbackEntryOrThrowLocked(long inode) throws ErrnoException {
+        final CallbackEntry entry = mCallbackMap.get(checkInode(inode));
+        if (entry == null) {
+            throw new ErrnoException("getCallbackEntryOrThrowLocked", OsConstants.ENOENT);
+        }
+        return entry;
+    }
+
+    private void replySimple(long unique, int result) {
         synchronized (mLock) {
-            try {
+            replySimpleLocked(unique, result);
-                getCallbackEntryOrThrowLocked(inode).callback.onFsync();
-                return 0;
-            } catch (ErrnoException exp) {
-                return getError(exp);
-            }
         }
     }
 
-    // Called by JNI.
+    private void replySimpleLocked(long unique, int result) {
-    @SuppressWarnings("unused")
+        if (mInstance != 0) {
-    private int onRelease(long inode) {
+            native_replySimple(mInstance, unique, result);
-        synchronized(mLock) {
-            try {
-                getCallbackEntryOrThrowLocked(inode).callback.onRelease();
-                return 0;
-            } catch (ErrnoException exp) {
-                return getError(exp);
-            } finally {
-                mCallbackMap.remove(checkInode(inode));
-            }
         }
     }
 
-    // Called by JNI.
+    native long native_new(int fd);
-    @SuppressWarnings("unused")
+    native void native_delete(long ptr);
-    private int onRead(long inode, long offset, int size, byte[] bytes) {
+    native void native_start(long ptr);
-        synchronized(mLock) {
-            try {
-                return getCallbackEntryOrThrowLocked(inode).callback.onRead(offset, size, bytes);
-            } catch (ErrnoException exp) {
-                return getError(exp);
-            }
-        }
-    }
 
-    // Called by JNI.
+    native void native_replySimple(long ptr, long unique, int result);
-    @SuppressWarnings("unused")
+    native void native_replyOpen(long ptr, long unique, long fh);
-    private int onWrite(long inode, long offset, int size, byte[] bytes) {
+    native void native_replyLookup(long ptr, long unique, long inode, long size);
-        synchronized(mLock) {
+    native void native_replyGetAttr(long ptr, long unique, long inode, long size);
-            try {
+    native void native_replyWrite(long ptr, long unique, int size);
-                return getCallbackEntryOrThrowLocked(inode).callback.onWrite(offset, size, bytes);
+    native void native_replyRead(long ptr, long unique, int size, byte[] bytes);
-            } catch (ErrnoException exp) {
-                return getError(exp);
-            }
-        }
-    }
-
-    private static int getError(@NonNull ErrnoException exp) {
-        // Should not return ENOSYS because the kernel stops
-        // dispatching the FUSE action once FUSE implementation returns ENOSYS for the action.
-        return exp.errno != OsConstants.ENOSYS ? -exp.errno : -OsConstants.EIO;
-    }
-
-    native boolean native_start_loop(int fd);
 
     private static int checkInode(long inode) {
         Preconditions.checkArgumentInRange(inode, MIN_INODE, Integer.MAX_VALUE, "checkInode");
@@ -223,10 +285,61 @@ public class FuseAppLoop {
 
     private static class CallbackEntry {
         final ProxyFileDescriptorCallback callback;
+        final Handler handler;
         boolean opened;
-        CallbackEntry(ProxyFileDescriptorCallback callback) {
+
-            Preconditions.checkNotNull(callback);
+        CallbackEntry(ProxyFileDescriptorCallback callback, Handler handler) {
-            this.callback = callback;
+            this.callback = Preconditions.checkNotNull(callback);
+            this.handler = Preconditions.checkNotNull(handler);
+        }
+
+        long getThreadId() {
+            return handler.getLooper().getThread().getId();
+        }
+
+        void postRunnable(Runnable runnable) throws ErrnoException {
+            final boolean result = handler.post(runnable);
+            if (!result) {
+                throw new ErrnoException("postRunnable", OsConstants.EBADF);
+            }
+        }
+    }
+
+    /**
+     * Entry for bytes map.
+     */
+    private static class BytesMapEntry {
+        int counter = 0;
+        byte[] bytes = new byte[FUSE_MAX_WRITE];
+    }
+
+    /**
+     * Map between Thread ID and byte buffer.
+     */
+    private static class BytesMap {
+        final Map<Long, BytesMapEntry> mEntries = new HashMap<>();
+
+        byte[] startUsing(long threadId) {
+            BytesMapEntry entry = mEntries.get(threadId);
+            if (entry == null) {
+                entry = new BytesMapEntry();
+                mEntries.put(threadId, entry);
+            }
+            entry.counter++;
+            return entry.bytes;
+        }
+
+        void stopUsing(long threadId) {
+            final BytesMapEntry entry = mEntries.get(threadId);
+            Preconditions.checkNotNull(entry);
+            entry.counter--;
+            if (entry.counter <= 0) {
+                mEntries.remove(threadId);
+            }
+        }
+
+        void clear() {
+            mEntries.clear();
         }
     }
 }

core/java/com/android/internal/os/FuseUnavailableMountException.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+package com.android.internal.os;
+
+/**
+ * Exception occurred when the mount point has already been unavailable.
+ */
+public class FuseUnavailableMountException extends Exception {
+    public FuseUnavailableMountException(int mountId) {
+        super("AppFuse mount point " + mountId + " is unavailable");
+    }
+}

core/jni/com_android_internal_os_FuseAppLoop.cpp

@@ -20,140 +20,214 @@
 #include <stdlib.h>
 #include <sys/stat.h>
 
+#include <map>
+#include <memory>
+
 #include <android_runtime/Log.h>
 #include <android-base/logging.h>
 #include <android-base/unique_fd.h>
 #include <jni.h>
 #include <libappfuse/FuseAppLoop.h>
 #include <nativehelper/ScopedLocalRef.h>
+#include <nativehelper/ScopedPrimitiveArray.h>
 
 #include "core_jni_helpers.h"
 
 namespace android {
-
 namespace {
-
 constexpr const char* CLASS_NAME = "com/android/internal/os/FuseAppLoop";
 
 jclass gFuseAppLoopClass;
-jmethodID gOnGetSizeMethod;
+jmethodID gOnCommandMethod;
 jmethodID gOnOpenMethod;
-jmethodID gOnFsyncMethod;
-jmethodID gOnReleaseMethod;
-jmethodID gOnReadMethod;
-jmethodID gOnWriteMethod;
 
 class Callback : public fuse::FuseAppLoopCallback {
 private:
-    static constexpr size_t kBufferSize = std::max(fuse::kFuseMaxWrite, fuse::kFuseMaxRead);
+    typedef ScopedLocalRef<jbyteArray> LocalBytes;
-    static_assert(kBufferSize <= INT32_MAX, "kBufferSize should be fit in int32_t.");
-
     JNIEnv* const mEnv;
     jobject const mSelf;
-    ScopedLocalRef<jbyteArray> mJniBuffer;
+    std::map<uint64_t, std::unique_ptr<LocalBytes>> mBuffers;
-
-    template <typename T>
-    T checkException(T result) const {
-        if (mEnv->ExceptionCheck()) {
-            LOGE_EX(mEnv, nullptr);
-            mEnv->ExceptionClear();
-            return -EIO;
-        }
-        return result;
-    }
 
 public:
     Callback(JNIEnv* env, jobject self) :
-        mEnv(env),
+        mEnv(env), mSelf(self) {}
-        mSelf(self),
-        mJniBuffer(env, nullptr) {}
 
-    bool Init() {
+    void OnLookup(uint64_t unique, uint64_t inode) override {
-        mJniBuffer.reset(mEnv->NewByteArray(kBufferSize));
+        mEnv->CallVoidMethod(mSelf, gOnCommandMethod, FUSE_LOOKUP, unique, inode, 0, 0, nullptr);
-        return mJniBuffer.get();
+        CHECK(!mEnv->ExceptionCheck());
     }
 
-    bool IsActive() override {
+    void OnGetAttr(uint64_t unique, uint64_t inode) override {
-        return true;
+        mEnv->CallVoidMethod(mSelf, gOnCommandMethod, FUSE_GETATTR, unique, inode, 0, 0, nullptr);
+        CHECK(!mEnv->ExceptionCheck());
     }
 
-    int64_t OnGetSize(uint64_t inode) override {
+    void OnOpen(uint64_t unique, uint64_t inode) override {
-        return checkException(mEnv->CallLongMethod(mSelf, gOnGetSizeMethod, inode));
+        const jbyteArray buffer = static_cast<jbyteArray>(mEnv->CallObjectMethod(
+                mSelf, gOnOpenMethod, unique, inode));
+        CHECK(!mEnv->ExceptionCheck());
+        if (buffer == nullptr) {
+            return;
         }
 
-    int32_t OnOpen(uint64_t inode) override {
+        mBuffers.insert(std::make_pair(inode, std::unique_ptr<LocalBytes>(
-        return checkException(mEnv->CallIntMethod(mSelf, gOnOpenMethod, inode));
+                new LocalBytes(mEnv, buffer))));
     }
 
-    int32_t OnFsync(uint64_t inode) override {
+    void OnFsync(uint64_t unique, uint64_t inode) override {
-        return checkException(mEnv->CallIntMethod(mSelf, gOnFsyncMethod, inode));
+        mEnv->CallVoidMethod(mSelf, gOnCommandMethod, FUSE_FSYNC, unique, inode, 0, 0, nullptr);
+        CHECK(!mEnv->ExceptionCheck());
     }
 
-    int32_t OnRelease(uint64_t inode) override {
+    void OnRelease(uint64_t unique, uint64_t inode) override {
-        return checkException(mEnv->CallIntMethod(mSelf, gOnReleaseMethod, inode));
+        mBuffers.erase(inode);
+        mEnv->CallVoidMethod(mSelf, gOnCommandMethod, FUSE_RELEASE, unique, inode, 0, 0, nullptr);
+        CHECK(!mEnv->ExceptionCheck());
     }
 
-    int32_t OnRead(uint64_t inode, uint64_t offset, uint32_t size, void* buffer) override {
+    void OnRead(uint64_t unique, uint64_t inode, uint64_t offset, uint32_t size) override {
-        CHECK_LE(size, static_cast<uint32_t>(kBufferSize));
+        CHECK_LE(size, static_cast<uint32_t>(fuse::kFuseMaxRead));
-        const int32_t result = checkException(mEnv->CallIntMethod(
+
-                mSelf, gOnReadMethod, inode, offset, size, mJniBuffer.get()));
+        auto it = mBuffers.find(inode);
-        if (result <= 0) {
+        CHECK(it != mBuffers.end());
-            return result;
+
-        }
+        mEnv->CallVoidMethod(
-        if (result > static_cast<int32_t>(size)) {
+                mSelf, gOnCommandMethod, FUSE_READ, unique, inode, offset, size,
-            LOG(ERROR) << "Returned size is too large.";
+                it->second->get());
-            return -EIO;
+        CHECK(!mEnv->ExceptionCheck());
     }
 
-        mEnv->GetByteArrayRegion(mJniBuffer.get(), 0, result, static_cast<jbyte*>(buffer));
+    void OnWrite(uint64_t unique, uint64_t inode, uint64_t offset, uint32_t size,
+            const void* buffer) override {
+        CHECK_LE(size, static_cast<uint32_t>(fuse::kFuseMaxWrite));
+
+        auto it = mBuffers.find(inode);
+        CHECK(it != mBuffers.end());
+
+        jbyteArray const javaBuffer = it->second->get();
+
+        mEnv->SetByteArrayRegion(javaBuffer, 0, size, static_cast<const jbyte*>(buffer));
         CHECK(!mEnv->ExceptionCheck());
 
-        return checkException(result);
+        mEnv->CallVoidMethod(
-    }
+                mSelf, gOnCommandMethod, FUSE_WRITE, unique, inode, offset, size, javaBuffer);
-
-    int32_t OnWrite(uint64_t inode, uint64_t offset, uint32_t size, const void* buffer) override {
-        CHECK_LE(size, static_cast<uint32_t>(kBufferSize));
-
-        mEnv->SetByteArrayRegion(mJniBuffer.get(), 0, size, static_cast<const jbyte*>(buffer));
         CHECK(!mEnv->ExceptionCheck());
-
-        return checkException(mEnv->CallIntMethod(
-                mSelf, gOnWriteMethod, inode, offset, size, mJniBuffer.get()));
     }
 };
 
-jboolean com_android_internal_os_FuseAppLoop_start_loop(JNIEnv* env, jobject self, jint jfd) {
+jlong com_android_internal_os_FuseAppLoop_new(JNIEnv* env, jobject self, jint jfd) {
-    base::unique_fd fd(jfd);
+    return reinterpret_cast<jlong>(new fuse::FuseAppLoop(base::unique_fd(jfd)));
-    Callback callback(env, self);
-
-    if (!callback.Init()) {
-        LOG(ERROR) << "Failed to init callback";
-        return JNI_FALSE;
 }
 
-    return fuse::StartFuseAppLoop(fd.release(), &callback);
+void com_android_internal_os_FuseAppLoop_delete(JNIEnv* env, jobject self, jlong ptr) {
+    delete reinterpret_cast<fuse::FuseAppLoop*>(ptr);
+}
+
+void com_android_internal_os_FuseAppLoop_start(JNIEnv* env, jobject self, jlong ptr) {
+    Callback callback(env, self);
+    reinterpret_cast<fuse::FuseAppLoop*>(ptr)->Start(&callback);
+}
+
+void com_android_internal_os_FuseAppLoop_replySimple(
+        JNIEnv* env, jobject self, jlong ptr, jlong unique, jint result) {
+    if (!reinterpret_cast<fuse::FuseAppLoop*>(ptr)->ReplySimple(unique, result)) {
+        reinterpret_cast<fuse::FuseAppLoop*>(ptr)->Break();
+    }
+}
+
+void com_android_internal_os_FuseAppLoop_replyOpen(
+        JNIEnv* env, jobject self, jlong ptr, jlong unique, jlong fh) {
+    if (!reinterpret_cast<fuse::FuseAppLoop*>(ptr)->ReplyOpen(unique, fh)) {
+        reinterpret_cast<fuse::FuseAppLoop*>(ptr)->Break();
+    }
+}
+
+void com_android_internal_os_FuseAppLoop_replyLookup(
+        JNIEnv* env, jobject self, jlong ptr, jlong unique, jlong inode, jint size) {
+    if (!reinterpret_cast<fuse::FuseAppLoop*>(ptr)->ReplyLookup(unique, inode, size)) {
+        reinterpret_cast<fuse::FuseAppLoop*>(ptr)->Break();
+    }
+}
+
+void com_android_internal_os_FuseAppLoop_replyGetAttr(
+        JNIEnv* env, jobject self, jlong ptr, jlong unique, jlong inode, jint size) {
+    if (!reinterpret_cast<fuse::FuseAppLoop*>(ptr)->ReplyGetAttr(
+            unique, inode, size, S_IFREG | 0777)) {
+        reinterpret_cast<fuse::FuseAppLoop*>(ptr)->Break();
+    }
+}
+
+void com_android_internal_os_FuseAppLoop_replyWrite(
+        JNIEnv* env, jobject self, jlong ptr, jlong unique, jint size) {
+    if (!reinterpret_cast<fuse::FuseAppLoop*>(ptr)->ReplyWrite(unique, size)) {
+        reinterpret_cast<fuse::FuseAppLoop*>(ptr)->Break();
+    }
+}
+
+void com_android_internal_os_FuseAppLoop_replyRead(
+        JNIEnv* env, jobject self, jlong ptr, jlong unique, jint size, jbyteArray data) {
+    ScopedByteArrayRO array(env, data);
+    CHECK(size >= 0);
+    CHECK(static_cast<size_t>(size) < array.size());
+    if (!reinterpret_cast<fuse::FuseAppLoop*>(ptr)->ReplyRead(unique, size, array.get())) {
+        reinterpret_cast<fuse::FuseAppLoop*>(ptr)->Break();
+    }
 }
 
 const JNINativeMethod methods[] = {
     {
-        "native_start_loop",
+        "native_new",
-        "(I)Z",
+        "(I)J",
-        (void *) com_android_internal_os_FuseAppLoop_start_loop
+        reinterpret_cast<void*>(com_android_internal_os_FuseAppLoop_new)
-    }
+    },
+    {
+        "native_delete",
+        "(J)V",
+        reinterpret_cast<void*>(com_android_internal_os_FuseAppLoop_delete)
+    },
+    {
+        "native_start",
+        "(J)V",
+        reinterpret_cast<void*>(com_android_internal_os_FuseAppLoop_start)
+    },
+    {
+        "native_replySimple",
+        "(JJI)V",
+        reinterpret_cast<void*>(com_android_internal_os_FuseAppLoop_replySimple)
+    },
+    {
+        "native_replyOpen",
+        "(JJJ)V",
+        reinterpret_cast<void*>(com_android_internal_os_FuseAppLoop_replyOpen)
+    },
+    {
+        "native_replyLookup",
+        "(JJJJ)V",
+        reinterpret_cast<void*>(com_android_internal_os_FuseAppLoop_replyLookup)
+    },
+    {
+        "native_replyGetAttr",
+        "(JJJJ)V",
+        reinterpret_cast<void*>(com_android_internal_os_FuseAppLoop_replyGetAttr)
+    },
+    {
+        "native_replyRead",
+        "(JJI[B)V",
+        reinterpret_cast<void*>(com_android_internal_os_FuseAppLoop_replyRead)
+    },
+    {
+        "native_replyWrite",
+        "(JJI)V",
+        reinterpret_cast<void*>(com_android_internal_os_FuseAppLoop_replyWrite)
+    },
 };
-
 }  // namespace
 
 int register_com_android_internal_os_FuseAppLoop(JNIEnv* env) {
     gFuseAppLoopClass = MakeGlobalRefOrDie(env, FindClassOrDie(env, CLASS_NAME));
-    gOnGetSizeMethod = GetMethodIDOrDie(env, gFuseAppLoopClass, "onGetSize", "(J)J");
+    gOnCommandMethod = GetMethodIDOrDie(env, gFuseAppLoopClass, "onCommand", "(IJJJI[B)V");
-    gOnOpenMethod = GetMethodIDOrDie(env, gFuseAppLoopClass, "onOpen", "(J)I");
+    gOnOpenMethod = GetMethodIDOrDie(env, gFuseAppLoopClass, "onOpen", "(JJ)[B");
-    gOnFsyncMethod = GetMethodIDOrDie(env, gFuseAppLoopClass, "onFsync", "(J)I");
-    gOnReleaseMethod = GetMethodIDOrDie(env, gFuseAppLoopClass, "onRelease", "(J)I");
-    gOnReadMethod = GetMethodIDOrDie(env, gFuseAppLoopClass, "onRead", "(JJI[B)I");
-    gOnWriteMethod = GetMethodIDOrDie(env, gFuseAppLoopClass, "onWrite", "(JJI[B)I");
     RegisterMethodsOrDie(env, CLASS_NAME, methods, NELEM(methods));
     return 0;
 }
-
 }  // namespace android

core/tests/coretests/src/android/os/storage/StorageManagerIntegrationTest.java

@@ -264,7 +264,7 @@ public class StorageManagerIntegrationTest extends StorageManagerBaseTest {
         final MyThreadFactory factory = new MyThreadFactory();
         int firstMountId;
         try (final ParcelFileDescriptor fd = mSm.openProxyFileDescriptor(
-                ParcelFileDescriptor.MODE_READ_ONLY, callback, factory)) {
+                ParcelFileDescriptor.MODE_READ_ONLY, callback, null, factory)) {
             assertNotSame(Thread.State.TERMINATED, factory.thread.getState());
             firstMountId = mSm.getProxyFileDescriptorMountPointId();
             assertNotSame(-1, firstMountId);
@@ -276,7 +276,7 @@ public class StorageManagerIntegrationTest extends StorageManagerBaseTest {
 
         // StorageManager should mount another bridge on the next open request.
         try (final ParcelFileDescriptor fd = mSm.openProxyFileDescriptor(
-                ParcelFileDescriptor.MODE_WRITE_ONLY, callback, factory)) {
+                ParcelFileDescriptor.MODE_WRITE_ONLY, callback, null, factory)) {
             assertNotSame(Thread.State.TERMINATED, factory.thread.getState());
             assertNotSame(firstMountId, mSm.getProxyFileDescriptorMountPointId());
         }

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

@@ -98,6 +98,7 @@ import com.android.internal.annotations.GuardedBy;
 import com.android.internal.app.IMediaContainerService;
 import com.android.internal.os.AppFuseMount;
 import com.android.internal.os.FuseAppLoop;
+import com.android.internal.os.FuseUnavailableMountException;
 import com.android.internal.os.SomeArgs;
 import com.android.internal.os.Zygote;
 import com.android.internal.util.ArrayUtils;
@@ -3007,10 +3008,18 @@ class StorageManagerService extends IStorageManager.Stub
         }
     }
 
-    private ParcelFileDescriptor mountAppFuse(int uid, int mountId)
+    class AppFuseMountScope extends AppFuseBridge.MountScope {
-            throws NativeDaemonConnectorException {
+        boolean opened = false;
+
+        public AppFuseMountScope(int uid, int pid, int mountId) {
+            super(uid, pid, mountId);
+        }
+
+        @Override
+        public ParcelFileDescriptor open() throws NativeDaemonConnectorException {
             final NativeDaemonEvent event = StorageManagerService.this.mConnector.execute(
                     "appfuse", "mount", uid, Process.myPid(), mountId);
+            opened = true;
             if (event.getFileDescriptors() == null ||
                 event.getFileDescriptors().length == 0) {
                 throw new NativeDaemonConnectorException("Cannot obtain device FD");
@@ -3018,21 +3027,17 @@ class StorageManagerService extends IStorageManager.Stub
             return new ParcelFileDescriptor(event.getFileDescriptors()[0]);
         }
 
-    class AppFuseMountScope extends AppFuseBridge.MountScope {
-        public AppFuseMountScope(int uid, int pid, int mountId)
-                throws NativeDaemonConnectorException {
-            super(uid, pid, mountId, mountAppFuse(uid, mountId));
-        }
-
         @Override
         public void close() throws Exception {
-            super.close();
+            if (opened) {
                 mConnector.execute("appfuse", "unmount", uid, Process.myPid(), mountId);
+                opened = false;
+            }
         }
     }
 
     @Override
-    public AppFuseMount mountProxyFileDescriptorBridge() throws RemoteException {
+    public @Nullable AppFuseMount mountProxyFileDescriptorBridge() {
         Slog.v(TAG, "mountProxyFileDescriptorBridge");
         final int uid = Binder.getCallingUid();
         final int pid = Binder.getCallingPid();
@@ -3049,12 +3054,12 @@ class StorageManagerService extends IStorageManager.Stub
                     final int name = mNextAppFuseName++;
                     try {
                         return new AppFuseMount(
-                            name,
+                            name, mAppFuseBridge.addBridge(new AppFuseMountScope(uid, pid, name)));
-                            mAppFuseBridge.addBridge(new AppFuseMountScope(uid, pid, name)));
+                    } catch (FuseUnavailableMountException e) {
-                    } catch (AppFuseBridge.BridgeException e) {
                         if (newlyCreated) {
                             // If newly created bridge fails, it's a real error.
-                            throw new RemoteException(e.getMessage());
+                            Slog.e(TAG, "", e);
+                            return null;
                         }
                         // It seems the thread of mAppFuseBridge has already been terminated.
                         mAppFuseBridge = null;
@@ -3067,19 +3072,21 @@ class StorageManagerService extends IStorageManager.Stub
     }
 
     @Override
-    public ParcelFileDescriptor openProxyFileDescriptor(int mountId, int fileId, int mode)
+    public @Nullable ParcelFileDescriptor openProxyFileDescriptor(
-            throws RemoteException {
+            int mountId, int fileId, int mode) {
-        Slog.v(TAG, "mountProxyFileDescriptorBridge");
+        Slog.v(TAG, "mountProxyFileDescriptor");
         final int pid = Binder.getCallingPid();
         try {
             synchronized (mAppFuseLock) {
                 if (mAppFuseBridge == null) {
-                    throw new RemoteException("Cannot find mount point");
+                    Slog.e(TAG, "FuseBridge has not been created");
+                    return null;
                 }
                 return mAppFuseBridge.openFile(pid, mountId, fileId, mode);
             }
-        } catch (FileNotFoundException | SecurityException | InterruptedException error) {
+        } catch (FuseUnavailableMountException | InterruptedException error) {
-            throw new RemoteException(error.getMessage());
+            Slog.v(TAG, "The mount point has already been invalid", error);
+            return null;
         }
     }
 

services/core/java/com/android/server/storage/AppFuseBridge.java

@@ -21,7 +21,9 @@ import android.system.ErrnoException;
 import android.system.Os;
 import android.util.SparseArray;
 import com.android.internal.annotations.GuardedBy;
+import com.android.internal.os.FuseUnavailableMountException;
 import com.android.internal.util.Preconditions;
+import com.android.server.NativeDaemonConnectorException;
 import libcore.io.IoUtils;
 import java.io.File;
 import java.io.FileNotFoundException;
@@ -54,17 +56,17 @@ public class AppFuseBridge implements Runnable {
     }
 
     public ParcelFileDescriptor addBridge(MountScope mountScope)
-            throws BridgeException {
+            throws FuseUnavailableMountException, NativeDaemonConnectorException {
         try {
             synchronized (this) {
                 Preconditions.checkArgument(mScopes.indexOfKey(mountScope.mountId) < 0);
                 if (mNativeLoop == 0) {
-                    throw new BridgeException("The thread has already been terminated");
+                    throw new FuseUnavailableMountException(mountScope.mountId);
                 }
                 final int fd = native_add_bridge(
-                        mNativeLoop, mountScope.mountId, mountScope.deviceFd.detachFd());
+                        mNativeLoop, mountScope.mountId, mountScope.open().detachFd());
                 if (fd == -1) {
-                    throw new BridgeException("Failed to invoke native_add_bridge");
+                    throw new FuseUnavailableMountException(mountScope.mountId);
                 }
                 final ParcelFileDescriptor result = ParcelFileDescriptor.adoptFd(fd);
                 mScopes.put(mountScope.mountId, mountScope);
@@ -86,12 +88,12 @@ public class AppFuseBridge implements Runnable {
     }
 
     public ParcelFileDescriptor openFile(int pid, int mountId, int fileId, int mode)
-            throws FileNotFoundException, SecurityException, InterruptedException {
+            throws FuseUnavailableMountException, InterruptedException {
         final MountScope scope;
         synchronized (this) {
             scope = mScopes.get(mountId);
             if (scope == null) {
-                throw new FileNotFoundException("Cannot find mount point");
+                throw new FuseUnavailableMountException(mountId);
             }
         }
         if (scope.pid != pid) {
@@ -99,17 +101,14 @@ public class AppFuseBridge implements Runnable {
         }
         final boolean result = scope.waitForMount();
         if (result == false) {
-            throw new FileNotFoundException("Mount failed");
+            throw new FuseUnavailableMountException(mountId);
         }
         try {
-            if (Os.stat(scope.mountPoint.getPath()).st_ino != 1) {
+            return ParcelFileDescriptor.open(
-                throw new FileNotFoundException("Could not find bridge mount point.");
+                    new File(scope.mountPoint, String.valueOf(fileId)), mode);
+        } catch (FileNotFoundException error) {
+            throw new FuseUnavailableMountException(mountId);
         }
-        } catch (ErrnoException e) {
-            throw new FileNotFoundException(
-                    "Failed to stat mount point: " + scope.mountPoint.getParent());
-        }
-        return ParcelFileDescriptor.open(new File(scope.mountPoint, String.valueOf(fileId)), mode);
     }
 
     // Used by com_android_server_storage_AppFuse.cpp.
@@ -130,20 +129,18 @@ public class AppFuseBridge implements Runnable {
         }
     }
 
-    public static class MountScope implements AutoCloseable {
+    public static abstract class MountScope implements AutoCloseable {
         public final int uid;
         public final int pid;
         public final int mountId;
-        public final ParcelFileDescriptor deviceFd;
         public final File mountPoint;
         private final CountDownLatch mMounted = new CountDownLatch(1);
         private boolean mMountResult = false;
 
-        public MountScope(int uid, int pid, int mountId, ParcelFileDescriptor deviceFd) {
+        public MountScope(int uid, int pid, int mountId) {
             this.uid = uid;
             this.pid = pid;
             this.mountId = mountId;
-            this.deviceFd = deviceFd;
             this.mountPoint = new File(String.format(APPFUSE_MOUNT_NAME_TEMPLATE,  uid, mountId));
         }
 
@@ -161,16 +158,7 @@ public class AppFuseBridge implements Runnable {
             return mMountResult;
         }
 
-        @Override
+        public abstract ParcelFileDescriptor open() throws NativeDaemonConnectorException;
-        public void close() throws Exception {
-            deviceFd.close();
-        }
-    }
-
-    public static class BridgeException extends Exception {
-        public BridgeException(String message) {
-            super(message);
-        }
     }
 
     private native long native_new();