Android 14 vold 分析（2）VolumeManager 和 NetlinkManger
3. VolumeManager::Instance() 和 VolumeManager::start()
system/vold/VolumeManager.cpp
3.1 Instance()没啥好说的 非常简单
112 VolumeManager* VolumeManager::Instance() {113 if (!sInstance) sInstance = new VolumeManager();114 return sInstance;115 }116 117 VolumeManager::VolumeManager() {118 mDebug = false;119 mNextObbId = 0;120 mNextStubId = 0;121 // For security reasons, assume that a secure keyguard is122 // showing until we hear otherwise123 mSecureKeyguardShowing = true;124 } 3.2 VolumeManager::start()
174 int VolumeManager::start() {175 ATRACE_NAME("VolumeManager::start");176 177 // Always start from a clean slate by unmounting everything in178 // directories that we own, in case we crashed.179 unmountAll(); -----> 全部 unmount ， 这里的unmount似乎并不是全部所有分区， 全部的话那还了得180 181 Loop::destroyAll();182 183 // Assume that we always have an emulated volume on internal184 // storage; the framework will decide if it should be mounted.185 CHECK(mInternalEmulatedVolumes.empty());186 187 auto vol = std::shared_ptr<android::vold::VolumeBase>(188 new android::vold::EmulatedVolume("/data/media", 0)); ---> 创建 EmulatedVolume189 vol->setMountUserId(0);190 vol->create();191 mInternalEmulatedVolumes.push_back(vol);192 193 // Consider creating a virtual disk194 updateVirtualDisk();195 196 return 0;197 }4. NetlinkManger::Instance() 和 NetlinkManger::start()
system/vold/NetlinkManager.cpp
4.1 NetlinkManger::Instance() 很简单 不需要赘述
36 NetlinkManager* NetlinkManager::Instance() {37 if (!sInstance) sInstance = new NetlinkManager();38 return sInstance;39 }40 41 NetlinkManager::NetlinkManager() {42 mBroadcaster = NULL;43 }
4.2 NetlinkManger::start()
47 int NetlinkManager::start() {48 struct sockaddr_nl nladdr;49 int sz = 64 * 1024;50 int on = 1;51 52 memset(&nladdr, 0, sizeof(nladdr));53 nladdr.nl_family = AF_NETLINK;54 nladdr.nl_pid = getpid();55 nladdr.nl_groups = 0xffffffff;56 57 if ((mSock = socket(PF_NETLINK, SOCK_DGRAM | SOCK_CLOEXEC, NETLINK_KOBJECT_UEVENT)) < 0) { ---> 创建socket client58 PLOG(ERROR) << "Unable to create uevent socket";59 return -1;60 }61 62 // When running in a net/user namespace, SO_RCVBUFFORCE will fail because63 // it will check for the CAP_NET_ADMIN capability in the root namespace.64 // Try using SO_RCVBUF if that fails.65 if ((setsockopt(mSock, SOL_SOCKET, SO_RCVBUFFORCE, &sz, sizeof(sz)) < 0) &&66 (setsockopt(mSock, SOL_SOCKET, SO_RCVBUF, &sz, sizeof(sz)) < 0)) {67 PLOG(ERROR) << "Unable to set uevent socket SO_RCVBUF/SO_RCVBUFFORCE option";68 goto out;69 }70 71 if (setsockopt(mSock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) {72 PLOG(ERROR) << "Unable to set uevent socket SO_PASSCRED option";73 goto out;74 }75 76 if (bind(mSock, (struct sockaddr*)&nladdr, sizeof(nladdr)) < 0) { --> socket bind77 PLOG(ERROR) << "Unable to bind uevent socket";78 goto out;79 }80 81 mHandler = new NetlinkHandler(mSock); --> 创建 new NetlinkHandler82 if (mHandler->start()) { --> 创建 new NetlinkHandler.start() 见4.383 PLOG(ERROR) << "Unable to start NetlinkHandler";84 goto out;85 }86 87 return 0;88 89 out:90 close(mSock);91 return -1;92 }4.3 new NetlinkHandler and start()
这有个继承关系NetlinkHandler : NetlinkListener : SocketListener
2 int NetlinkHandler::start() {33 return this->startListener(); ------> 实际就是SocketListener poll监听，是否有POLLIN 产生, onDataAvailable -> onEvent34 }35 36 void NetlinkHandler::onEvent(NetlinkEvent* evt) { ---> 收到了uevent37 VolumeManager* vm = VolumeManager::Instance();38 const char* subsys = evt->getSubsystem();39 40 if (!subsys) {41 LOG(WARNING) << "No subsystem found in netlink event";42 return;43 }44 45 if (std::string(subsys) == "block") { ------> 只有uevent的subsys是block才会处理的46 vm->handleBlockEvent(evt); ------> VolumeManager处理 block device uevent 见 4.447 }48 }
4.4 VolumeManager::handleBlockEvent()
199 void VolumeManager::handleBlockEvent(NetlinkEvent* evt) {200 std::lock_guard<std::mutex> lock(mLock);201 202 if (mDebug) {203 LOG(DEBUG) << "----------------";204 LOG(DEBUG) << "handleBlockEvent with action " << (int)evt->getAction(); ---> 这里是vold.debug控制的，打印具体的action205 evt->dump();206 }207 208 std::string eventPath(evt->findParam("DEVPATH") ? evt->findParam("DEVPATH") : "");209 std::string devType(evt->findParam("DEVTYPE") ? evt->findParam("DEVTYPE") : "");210 211 if (devType != "disk") return; ---> devType不是disk还不处理， 真是牛逼哄哄212 213 int major = std::stoi(evt->findParam("MAJOR"));214 int minor = std::stoi(evt->findParam("MINOR"));215 dev_t device = makedev(major, minor); ---> 创建block device组合216 217 switch (evt->getAction()) {218 case NetlinkEvent::Action::kAdd: { ---> uevent action为add 具体见4.5219 for (const auto& source : mDiskSources) { ---> 之前添加的两个disksource，还记得吗，只支持sd卡和U盘220 if (source->matches(eventPath)) {221 // For now, assume that MMC and virtio-blk (the latter is222 // specific to virtual platforms; see Utils.cpp for details)223 // devices are SD, and that everything else is USB224 int flags = source->getFlags();225 if (major == kMajorBlockMmc || IsVirtioBlkDevice(major)) {226 flags |= android::vold::Disk::Flags::kSd; ---> SD卡227 } else {228 flags |= android::vold::Disk::Flags::kUsb; ---> usb storage, 通过otg插入的229 }230 231 auto disk =232 new android::vold::Disk(eventPath, device, source->getNickname(), flags); ---> 创建一个disk设备节点mknod233 handleDiskAdded(std::shared_ptr<android::vold::Disk>(disk)); --> 真正的处理234 break;235 }236 }237 break;238 }239 case NetlinkEvent::Action::kChange: { --> uevent action为add 具体见4.6240 LOG(VERBOSE) << "Disk at " << major << ":" << minor << " changed";241 handleDiskChanged(device);242 break;243 }244 case NetlinkEvent::Action::kRemove: { --> uevent action为add 具体见4.7245 handleDiskRemoved(device);246 break;247 }248 default: {249 LOG(WARNING) << "Unexpected block event action " << (int)evt->getAction();250 break;251 }252 }253 } 4.5 new android::vold::Disk()和handleDiskAdded()
system/vold/model/Disk.cpp
4.5.1 new android::vold::Disk()
Disk::Disk(const std::string& eventPath, dev_t device, const std::string& nickname, int flags)95 : mDevice(device),96 mSize(-1),97 mNickname(nickname),98 mFlags(flags),99 mCreated(false),100 mJustPartitioned(false) {101 mId = StringPrintf("disk:%u,%u", major(device), minor(device));102 mEventPath = eventPath;103 mSysPath = StringPrintf("/sys/%s", eventPath.c_str());104 mDevPath = StringPrintf("/dev/block/vold/%s", mId.c_str());105 CreateDeviceNode(mDevPath, mDevice); ---------> 创建block device 的设备节点mknod106 } 4.5.2 handleDiskAdded()
255 void VolumeManager::handleDiskAdded(const std::shared_ptr<android::vold::Disk>& disk) {256 // For security reasons, if secure keyguard is showing, wait257 // until the user unlocks the device to actually touch it258 // Additionally, wait until user 0 is actually started, since we need259 // the user to be up before we can mount a FUSE daemon to handle the disk.260 bool userZeroStarted = mStartedUsers.find(0) != mStartedUsers.end();261 if (mSecureKeyguardShowing) {262 LOG(INFO) << "Found disk at " << disk->getEventPath()263 << " but delaying scan due to secure keyguard";264 mPendingDisks.push_back(disk);265 } else if (!userZeroStarted) {266 LOG(INFO) << "Found disk at " << disk->getEventPath()267 << " but delaying scan due to user zero not having started";268 mPendingDisks.push_back(disk);269 } else {270 disk->create(); ---------> disk->create()271 mDisks.push_back(disk);272 }273 }146 status_t Disk::create() {147 CHECK(!mCreated);148 mCreated = true;149 150 auto listener = VolumeManager::Instance()->getListener(); ---------> StorageManaerService通信151 if (listener) listener->onDiskCreated(getId(), mFlags); ------> StorageManaerService->onDiskCreated()152 153 if (isStub()) {154 createStubVolume();155 return OK;156 }157 readMetadata(); --------> listener->onDiskMetadataChanged(getId(), mSize, mLabel, mSysPath);158 readPartitions(); --------> Disk::createPublicVolume() listener->onVolumeCreated()and listener->onDiskScanned()159 return OK;160 }思考， vold比mount service启动的早，那开机时vold获取到的listener为空，也就是说虽然disk创建了但是不会mount，那什么时候才会mount呢？ 我们下一篇文章解答