Android 8.1 OTG U盘无法显示在系统文件管理的修改

文件：frameworks\base\services\core\java\com\android\server\StorageManagerService.java
函数：private void onVolumeCreatedLocked(VolumeInfo vol)

如下修改：

    private void onVolumeCreatedLocked(VolumeInfo vol) {
		......

        if (vol.type == VolumeInfo.TYPE_EMULATED) {
        
		......
		
        } else if (vol.type == VolumeInfo.TYPE_PUBLIC) {
			......

            // Adoptable public disks are visible to apps, since they meet
            // public API requirement of being in a stable location.
            /**********************************************************************/
            //if (vol.disk.isAdoptable()) {		//注释掉这个判断
                vol.mountFlags |= VolumeInfo.MOUNT_FLAG_VISIBLE;
            //}
            /**********************************************************************/

			......
    }

上面的修改，在U盘mount的时候会起作用：
文件：system/vold/PublicVolume.cpp
函数：status_t PublicVolume::doMount()

status_t PublicVolume::doMount() {
    // TODO: expand to support mounting other filesystems
    readMetadata();
    ......

    setInternalPath(mRawPath);
    if (getMountFlags() & MountFlags::kVisible) {	//这里有判断，使用storage挂载路径
        setPath(StringPrintf("/storage/%s", stableName.c_str()));
    } else {
        setPath(mRawPath);
    }

	......

    if (!(getMountFlags() & MountFlags::kVisible)) {	//这里也有判断，会继续执行后面的创建用户空间文件系统
        // Not visible to apps, so no need to spin up FUSE
        return OK;
    }

	......
    return OK;
}