Android平台mass storage相关代码

代码

frameworks/base/services/java/com/android/server/MountService.java

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

frameworks/base/core/java/android/os/storage/StorageVolume.java     

frameworks/base/services/java/com/android/server/usb/UsbDeviceManager.java

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

frameworks/base/services/core/java/com/android/server/NativeDaemonConnector.java

frameworks/base/packages/SystemUI/src/com/android/systemui/usb/StorageNotification.java

frameworks/base/packages/SystemUI/src/com/android/systemui/usb/UsbStorageActivity.java

system/vold

 

对于Mass Storage，上层软件（kernel之上）只做了两件事

1.  Set sys.usb.config=mass_storage

在Settings设置mtp后，代码执行

Usbanager.SetCurrentFunction()

    ->UsbService.SetCurrentFunction()

        ->UsbDeviceManager.setCurrentFunctions()

             -> mHandler.sendMessage(MSG_SET_CURRENT_FUNCTIONS)

                   ->setEnabledFunctions(functions, makeDefault);

                       ->SystemProperties.set("persist.sys.usb.config", functions);

 

2.  Write /dev/block/vold/majorid:minored  to /sys/class/android_usb/android0/f_mass_storage/lun/file.

这个调用还挺复杂的，这个UI做的实在不好，一般人估计找不到。这个UI完全可以放在UsbSettings.java里。只需在USB_STATE=configured时调用StorageManager.java的enableUsbMassStorage()    就行，只是要放在一个单独线程中进行。

frameworks/base/services/usb/java/com/android/server/usb/UsbDeviceManager.java

updateState  

    sendMessage(MSG_UPDATE_STATE);

      updateUsbState

        broadcast Intent(ACTION_USB_STATE);

 

frameworks/base/services/core/java/com/android/server/MountService.java 

        //if (primary != null && primary.allowMassStorage()) {

            Slog.i(TAG, "registerReceiver ACTION_USB_STATE");

            mContext.registerReceiver(

                    mUsbReceiver, new IntentFilter(UsbManager.ACTION_USB_STATE), null, mHandler);

        //}

 

  private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {

        @Override

        public void onReceive(Context context, Intent intent) {

            boolean available = (intent.getBooleanExtra(UsbManager.USB_CONNECTED, false) &&

                    intent.getBooleanExtra(UsbManager.USB_FUNCTION_MASS_STORAGE, false));

            notifyShareAvailabilityChange(available);

        }

    };

 

notifyShareAvailabilityChange ()

   bl.mListener.onUsbMassStorageConnectionChanged(avail);

 

 

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

private class MountServiceBinderListener extends IMountServiceListener.Stub {

   public void onUsbMassStorageConnectionChanged(boolean available) {

       final int size = mListeners.size();

       for (int i = 0; i < size; i++) {

           mListeners.get(i).sendShareAvailabilityChanged(available);

       }

   }

 

UmsConnectionChangedStorageEvent

  super(EVENT_UMS_CONNECTION_CHANGED);

 

     void sendShareAvailabilityChanged(boolean available) {

           UmsConnectionChangedStorageEvent e = new UmsConnectionChangedStorageEvent(available);

           mHandler.sendMessage(e.getMessage()); ->send StorageEvent.EVENT_UMS_CONNECTION_CHANGED

       }

 

if (msg.what == StorageEvent.EVENT_UMS_CONNECTION_CHANGED) {

    mStorageEventListener.onUsbMassStorageConnectionChanged(ev.available);

 

 

frameworks/base/packages/SystemUI/src/com/android/systemui/usb/StorageNotification.java

onUsbMassStorageConnectionChanged  

  onUsbMassStorageConnectionChangedAsync

    updateUsbMassStorageNotification(true)

       setUsbStorageNotification

 

frameworks/base/packages/SystemUI/src/com/android/systemui/usb/UsbStorageActivity.java

DLG_CONFIRM_KILL_STORAGE_USERS

   switchUsbMassStorage(true)

 

private void switchUsbMassStorage(final boolean on) 

                enableUsbMassStorage()     StorageManager.java

                  setUsbMassStorageEnabled()  MountService.java

                    UmsEnableCallBack 

                       handleFinished()

                          doShareUnshareVolume()

                    send(H_UNMOUNT_PM_UPDATE)

                       mPms.updateExternalMediaStatus(false, true);

                       mForceUnmounts.add(ucb)

                         

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

updateExternalMediaStatus()

   sendMessage(UPDATED_MEDIA_STATUS)

     PackageHelper.getMountService().finishMediaUpdate();

 

frameworks\base\services\core\java\com\android\server\MountService.java

finishMediaUpdate()

  sendEmptyMessage(H_UNMOUNT_PM_DONE);            

    H_UNMOUNT_PM_DONE

     sendMessage(H_UNMOUNT_MS)

       H_UNMOUNT_MS

                UnmountCallBack.handleFinished()

                         doUnmountVolume()

                               final Command cmd = new Command("volume", "unmount", path);

                               mConnector.execute(cmd);

                         doShareUnshareVolume()

            

MTP->Mass Storage，先通知其他packages要unmount SD卡，然后unmount SD卡，然后才shareVolume

 

    doShareUnshareVolume  MountService.java

       mConnector.execute("volume", enable ? "share" : "unshare", path, method);

           execute(int timeout, String cmd, Object... args)  NativeDaemonConnector.java

               CommandListener::VolumeCmd::runCommand   system/vold/CommandListener.cpp

                    rc = vm->shareVolume(argv[2], argv[3]);       system/vold/VolumeManager.cpp

                       fd = open(MASS_STORAGE_FILE_PATH, O_WRONLY))

                       write(fd, nodepath, strlen(nodepath)) < 0)

                       v->handleVolumeShared();

                           setState(Volume::State_Shared);  system/vold/DirectVolume.cpp

 

 

system/vold/VolumeManager.cpp

#define MASS_STORAGE_FILE_PATH  "/sys/class/android_usb/android0/f_mass_storage/lun/file"

#define UICC0_MASS_STORAGE_PATH  "/sys/class/android_usb/android0/f_mass_storage/uicc0/file"

snprintf(nodepath,sizeof(nodepath), "/dev/block/vold/%d:%d", major(d), minor(d));

 

MountService的启动

SystemServer

   mountService = new MountService(context);

       readStorageListLocked();

           addVolumeLocked()

       registerReceiver(UsbManager.ACTION_USB_STATE)

       create NativeDaemonConnector to communicate with vold  (listenToSocket() for handling information from vold; execute() send data to vold)

   ServiceManager.addService("mount", mountService);

 

readStorageListLocked()

Read from  storage_list.xml     document:http://source.android.com/tech/storage/

google:frameworks/base/core/res/res/xml/storage_list.xml    

 

 简单介绍下vold

main() in main.cpp

  vm->start()          volume manager

  process_config()

                  get fstable from fstab.qcom

                  addPath()  system/vold/DirectVolume.cpp

                     mPaths->push_back(strdup(path));  push to the end of the list

                  addVolume()  system/vold/VolumeManager.cpp

                     mVolumes->push_back(v);

                nm->start()          netlink manager

                cl->startListener()  command listener    

 

handleBlockEvent() in system\vold\DirectVolume.cpp

  receive NetlinkEvent::NlActionAdd from kernel

     createDeviceNode /dev/block/vold/179:64

     handleDiskAdded(dp, evt); (sdcard)

     handlePartitionAdded(dp, evt) (usb disk)

 

VoldResponseCode.VolumeUserLabelChange

handleSystemReady()

  doMountVolume()的调用

    mConnector.execute("volume", "mount", path); send to vold-commandlistener

      VolumeCmd::runCommand   system\vold\CommandListener.cpp

        vm->mountVolume(argv[2]);   system\vold\VolumeManager.cpp

          Volume->mountVol()    system\vold\Volume.cpp

            Fat::check     system/vold/Fat.cpp

            Fat::doMount   system/vold/Fat.cpp

               mount(fsPath, mountPoint, "vfat", flags, mountData);

                 bionic/libc/arch-arm/syscalls/mount.S (syscall kernel/arch/arm/kernel/calls.S)

                   vfat_mount   kernel/fs/fat/namei_vfat.c

                   msdos_mount  kernel/fs/fat/namei_msdos.c

                      mount_bdev  kernel/fs/super.c

 

注意两个配置文件

Fstab文件和storage_list.xml