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

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