Implement WSLA API to unmount & detach disks (#13364)

* Implement WSLA API to unmount & detach disks

* Add WSL2_TEST_ONLY();

* Fix wslg path

src/linux/init/LSWInit.cpp

@@ -427,6 +427,18 @@ void HandleMessageImpl(wsl::shared::SocketChannel& Channel, const LSW_SIGNAL& Me
     Channel.SendResultMessage(result < 0 ? errno : 0);
 }
 
+void HandleMessageImpl(wsl::shared::SocketChannel& Channel, const LSW_UNMOUNT& Message, const gsl::span<gsl::byte>& Buffer)
+{
+    Channel.SendResultMessage<int32_t>(umount(Message.Buffer) == 0 ? 0 : errno);
+}
+
+void HandleMessageImpl(wsl::shared::SocketChannel& Channel, const LSW_DETACH& Message, const gsl::span<gsl::byte>& Buffer)
+{
+    sync();
+
+    Channel.SendResultMessage<int32_t>(DetachScsiDisk(Message.Lun));
+}
+
 template <typename TMessage, typename... Args>
 void HandleMessage(wsl::shared::SocketChannel& Channel, LX_MESSAGE_TYPE Type, const gsl::span<gsl::byte>& Buffer)
 {
@@ -461,7 +473,7 @@ void ProcessMessage(wsl::shared::SocketChannel& Channel, LX_MESSAGE_TYPE Type, c
 {
     try
     {
-        HandleMessage<LSW_GET_DISK, LSW_MOUNT, LSW_EXEC, LSW_FORK, LSW_CONNECT, LSW_WAITPID, LSW_SIGNAL, LSW_TTY_RELAY, LSW_PORT_RELAY>(
+        HandleMessage<LSW_GET_DISK, LSW_MOUNT, LSW_EXEC, LSW_FORK, LSW_CONNECT, LSW_WAITPID, LSW_SIGNAL, LSW_TTY_RELAY, LSW_PORT_RELAY, LSW_UNMOUNT, LSW_DETACH>(
             Channel, Type, Buffer);
     }
     catch (...)

src/shared/inc/lxinitshared.h

@@ -384,6 +384,8 @@ typedef enum _LX_MESSAGE_TYPE
     LxMessageLswMapPort,
     LxMessageLswConnectRelay,
     LxMessageLswPortRelay,
+    LxMessageLswUnmount,
+    LxMessageLswDetach,
 } LX_MESSAGE_TYPE,
     *PLX_MESSAGE_TYPE;
 
@@ -488,6 +490,8 @@ inline auto ToString(LX_MESSAGE_TYPE messageType)
         X(LxMessageLswMapPort)
         X(LxMessageLswConnectRelay)
         X(LxMessageLswPortRelay)
+        X(LxMessageLswUnmount)
+        X(LxMessageLswDetach)
     default:
         return "<unexpected LX_MESSAGE_TYPE>";
     }
@@ -1760,6 +1764,31 @@ struct LSW_PORT_RELAY
     PRETTY_PRINT(FIELD(Header));
 };
 
+struct LSW_UNMOUNT
+{
+    static inline auto Type = LxMessageLswUnmount;
+    using TResponse = RESULT_MESSAGE<int32_t>;
+
+    DECLARE_MESSAGE_CTOR(LSW_UNMOUNT);
+    MESSAGE_HEADER Header;
+
+    char Buffer[];
+
+    PRETTY_PRINT(FIELD(Header), FIELD(Buffer));
+};
+
+struct LSW_DETACH
+{
+    static inline auto Type = LxMessageLswDetach;
+    using TResponse = RESULT_MESSAGE<int32_t>;
+
+    DECLARE_MESSAGE_CTOR(LSW_DETACH);
+    MESSAGE_HEADER Header;
+    unsigned int Lun;
+
+    PRETTY_PRINT(FIELD(Header), FIELD(Lun));
+};
+
 typedef struct _LX_MINI_INIT_IMPORT_RESULT
 {
     static inline auto Type = LxMiniInitMessageImportResult;

src/windows/lswclient/DllMain.cpp

@@ -111,9 +111,9 @@ CATCH_RETURN();
 HRESULT WslAttachDisk(LSWVirtualMachineHandle VirtualMachine, const DiskAttachSettings* Settings, AttachedDiskInformation* AttachedDisk)
 {
     wil::unique_cotaskmem_ansistring device;
-    RETURN_IF_FAILED(reinterpret_cast<ILSWVirtualMachine*>(VirtualMachine)->AttachDisk(Settings->WindowsPath, Settings->ReadOnly, &device));
+    RETURN_IF_FAILED(reinterpret_cast<ILSWVirtualMachine*>(VirtualMachine)
+                         ->AttachDisk(Settings->WindowsPath, Settings->ReadOnly, &device, &AttachedDisk->ScsiLun));
 
-    // TODO: wire LUN
     auto deviceSize = strlen(device.get());
     WI_VERIFY(deviceSize < sizeof(AttachedDiskInformation::Device));
 
@@ -285,6 +285,15 @@ try
 }
 CATCH_RETURN();
 
+HRESULT WslUnmount(LSWVirtualMachineHandle VirtualMachine, const char* Path)
+{
+    return reinterpret_cast<ILSWVirtualMachine*>(VirtualMachine)->Unmount(Path);
+}
+
+HRESULT WslDetachDisk(LSWVirtualMachineHandle VirtualMachine, ULONG Lun)
+{
+    return reinterpret_cast<ILSWVirtualMachine*>(VirtualMachine)->DetachDisk(Lun);
+}
 EXTERN_C BOOL STDAPICALLTYPE DllMain(_In_ HINSTANCE Instance, _In_ DWORD Reason, _In_opt_ LPVOID Reserved)
 {
     wil::DLLMain(Instance, Reason, Reserved);

src/windows/lswclient/LSWApi.h

@@ -179,6 +179,10 @@ HRESULT WslMapPort(LSWVirtualMachineHandle VirtualMachine, const struct PortMapp
 
 HRESULT WslUnmapPort(LSWVirtualMachineHandle VirtualMachine, const struct PortMappingSettings* Settings);
 
+HRESULT WslUnmount(LSWVirtualMachineHandle VirtualMachine, const char* Path);
+
+HRESULT WslDetachDisk(LSWVirtualMachineHandle VirtualMachine, ULONG Lun);
+
 enum WslInstallComponent
 {
     WslInstallComponentNone = 0,

src/windows/lswclient/lswclient.def

@@ -14,6 +14,8 @@ EXPORTS
     WslLaunchDebugShell
     WslMapPort
     WslUnmapPort
+    WslDetachDisk
+    WslUnmount
     WslQueryMissingComponents
     WslInstallComponents
-    WslSetPackageUrl
+    WslSetPackageUrl

src/windows/service/exe/LSWVirtualMachine.cpp

@@ -331,7 +331,7 @@ void LSWVirtualMachine::OnExit(_In_ const HCS_EVENT* Event)
     }
 }
 
-HRESULT LSWVirtualMachine::AttachDisk(_In_ PCWSTR Path, _In_ BOOL ReadOnly, _Out_ LPSTR* Device)
+HRESULT LSWVirtualMachine::AttachDisk(_In_ PCWSTR Path, _In_ BOOL ReadOnly, _Out_ LPSTR* Device, _Out_ ULONG* Lun)
 try
 {
     *Device = nullptr;
@@ -345,35 +345,35 @@ try
             wsl::windows::common::hcs::GrantVmAccess(m_vmIdString.c_str(), Path);
         }
 
-        ULONG lun = 0;
-        while (m_attachedDisks.find(lun) != m_attachedDisks.end())
+        *Lun = 0;
+        while (m_attachedDisks.find(*Lun) != m_attachedDisks.end())
         {
-            lun++;
+            (*Lun)++;
         }
 
         bool vhdAdded = false;
         auto cleanup = wil::scope_exit_log(WI_DIAGNOSTICS_INFO, [&]() {
             if (vhdAdded)
             {
-                wsl::windows::common::hcs::RemoveScsiDisk(m_computeSystem.get(), lun);
+                wsl::windows::common::hcs::RemoveScsiDisk(m_computeSystem.get(), *Lun);
             }
 
             wsl::windows::common::hcs::RevokeVmAccess(m_vmIdString.c_str(), Path);
         });
 
-        wsl::windows::common::hcs::AddVhd(m_computeSystem.get(), Path, lun, ReadOnly);
+        wsl::windows::common::hcs::AddVhd(m_computeSystem.get(), Path, *Lun, ReadOnly);
         vhdAdded = true;
 
         LSW_GET_DISK message{};
         message.Header.MessageSize = sizeof(message);
         message.Header.MessageType = LSW_GET_DISK::Type;
-        message.ScsiLun = lun;
+        message.ScsiLun = *Lun;
         const auto& response = m_initChannel.Transaction(message);
 
         THROW_HR_IF_MSG(E_FAIL, response.Result != 0, "Failed to attach disk, init returned: %lu", response.Result);
 
         cleanup.release();
-        m_attachedDisks.emplace(lun, AttachedDisk{Path, response.Buffer});
+        m_attachedDisks.emplace(*Lun, AttachedDisk{Path, response.Buffer});
 
         *Device = wil::make_unique_ansistring<wil::unique_cotaskmem_ansistring>(response.Buffer).release();
     });
@@ -431,6 +431,49 @@ try
 }
 CATCH_RETURN();
 
+HRESULT LSWVirtualMachine::Unmount(_In_ const char* Path)
+try
+{
+    auto [pid, _, subChannel] = Fork(LSW_FORK::Thread);
+
+    wsl::shared::MessageWriter<LSW_UNMOUNT> message;
+    message.WriteString(Path);
+
+    const auto& response = subChannel.Transaction<LSW_UNMOUNT>(message.Span());
+
+    // TODO: Return errno to caller
+    THROW_HR_IF(E_FAIL, response.Result != 0);
+
+    return S_OK;
+}
+CATCH_RETURN()
+
+HRESULT LSWVirtualMachine::DetachDisk(_In_ ULONG Lun)
+try
+{
+    std::lock_guard lock{m_lock};
+
+    // Find the disk
+    auto it = m_attachedDisks.find(Lun);
+    RETURN_HR_IF(HRESULT_FROM_WIN32(ERROR_NOT_FOUND), it == m_attachedDisks.end());
+
+    // Detach it from the guest
+    LSW_DETACH message;
+    message.Lun = Lun;
+    const auto& response = m_initChannel.Transaction(message);
+
+    // TODO: Return errno to caller
+    THROW_HR_IF(E_FAIL, response.Result != 0);
+
+    // Remove it from the VM
+    m_attachedDisks.erase(it);
+
+    hcs::RemoveScsiDisk(m_computeSystem.get(), Lun);
+
+    return S_OK;
+}
+CATCH_RETURN()
+
 std::tuple<int32_t, int32_t, wsl::shared::SocketChannel> LSWVirtualMachine::Fork(enum LSW_FORK::ForkType Type)
 {
     std::lock_guard lock{m_lock};

src/windows/service/exe/LSWVirtualMachine.h

@@ -28,7 +28,7 @@ public:
 
     void Start();
 
-    IFACEMETHOD(AttachDisk(_In_ PCWSTR Path, _In_ BOOL ReadOnly, _Out_ LPSTR* Device)) override;
+    IFACEMETHOD(AttachDisk(_In_ PCWSTR Path, _In_ BOOL ReadOnly, _Out_ LPSTR* Device, _Out_ ULONG* Lun)) override;
     IFACEMETHOD(Mount(_In_ LPCSTR Source, _In_ LPCSTR Target, _In_ LPCSTR Type, _In_ LPCSTR Options, _In_ ULONG Flags)) override;
     IFACEMETHOD(CreateLinuxProcess(
         _In_ const LSW_CREATE_PROCESS_OPTIONS* Options, _In_ ULONG FdCount, _In_ LSW_PROCESS_FD* Fd, _Out_ HANDLE* Handles, _Out_ LSW_CREATE_PROCESS_RESULT* Result)) override;
@@ -38,6 +38,8 @@ public:
     IFACEMETHOD(RegisterCallback(_In_ ITerminationCallback* callback)) override;
     IFACEMETHOD(GetDebugShellPipe(_Out_ LPWSTR* pipePath)) override;
     IFACEMETHOD(MapPort(_In_ int Family, _In_ short WindowsPort, _In_ short LinuxPort, _In_ BOOL Remove)) override;
+    IFACEMETHOD(Unmount(_In_ const char* Path)) override;
+    IFACEMETHOD(DetachDisk(_In_ ULONG Lun)) override;
 
 private:
     static void CALLBACK s_OnExit(_In_ HCS_EVENT* Event, _In_opt_ void* Context);

src/windows/service/inc/wslservice.idl

@@ -449,7 +449,7 @@ interface ITerminationCallback : IUnknown
 ]
 interface ILSWVirtualMachine : IUnknown
 {
-    HRESULT AttachDisk([in] LPCWSTR Path, [in] BOOL ReadOnly, [out] LPSTR* Device);
+    HRESULT AttachDisk([in] LPCWSTR Path, [in] BOOL ReadOnly, [out] LPSTR* Device, [out] ULONG* Lun);
     HRESULT Mount([in, unique] LPCSTR Source, [in] LPCSTR Target, [in] LPCSTR Type, [in] LPCSTR Options, [in] ULONG Flags); 
     HRESULT CreateLinuxProcess([in] const LSW_CREATE_PROCESS_OPTIONS* Options, [in] ULONG FdCount, [in, unique, size_is(FdCount)] LSW_PROCESS_FD* Fds, [out, size_is(FdCount)] HVSOCKET_HANDLE* Handles, [out] LSW_CREATE_PROCESS_RESULT* Result);
     HRESULT WaitPid([in] LONG Pid, [in] ULONGLONG TimeoutMs,  [out] ULONG* State, [out] int* Code);
@@ -458,6 +458,8 @@ interface ILSWVirtualMachine : IUnknown
     HRESULT RegisterCallback([in] ITerminationCallback* terminationCallback);
     HRESULT GetDebugShellPipe([out] LPWSTR* pipePath);
     HRESULT MapPort([in] int Family, [in] short WindowsPort, [in] short LinuxPort, [in] BOOL Remove);
+    HRESULT Unmount([in] LPCSTR Path);
+    HRESULT DetachDisk([in] ULONG Lun);
 }
 
 typedef

test/windows/LSWTests.cpp

@@ -122,6 +122,64 @@ class LSWTests
         return vm;
     }
 
+    TEST_METHOD(AttachDetach)
+    {
+        WSL2_TEST_ONLY();
+
+        VirtualMachineSettings settings{};
+        settings.CPU.CpuCount = 4;
+        settings.DisplayName = L"LSW";
+        settings.Memory.MemoryMb = 1024;
+        settings.Options.BootTimeoutMs = 30000;
+        auto vm = CreateVm(&settings);
+
+#ifdef WSL_DEV_INSTALL_PATH
+
+        auto vhdPath = std::filesystem::path(WSL_DEV_INSTALL_PATH) / "system.vhd";
+#else
+
+        auto msiPath = wsl::windows::common::wslutil::GetMsiPackagePath();
+        VERIFY_IS_TRUE(msiPath.has_value());
+
+        auto vhdPath = std::filesystem::path(msiPath.value()) / "system.vhd";
+
+#endif
+
+        auto blockDeviceExists = [&](ULONG Lun) {
+            std::string device = std::format("/sys/bus/scsi/devices/0:0:0:{}", Lun);
+            std::vector<const char*> cmd{"/usr/bin/test", "-d", device.c_str()};
+            return RunCommand(vm.get(), cmd) == 0;
+        };
+
+        // Attach the disk.
+        DiskAttachSettings attachSettings{vhdPath.c_str(), true};
+        AttachedDiskInformation attachedDisk{};
+        VERIFY_SUCCEEDED(WslAttachDisk(vm.get(), &attachSettings, &attachedDisk));
+        VERIFY_IS_TRUE(blockDeviceExists(attachedDisk.ScsiLun));
+
+        // Mount it to /mnt.
+        MountSettings mountSettings{attachedDisk.Device, "/mnt", "ext4", "ro"};
+        VERIFY_SUCCEEDED(WslMount(vm.get(), &mountSettings));
+
+        // Validate that the mountpoint is present.
+        std::vector<const char*> cmd{"/usr/bin/mountpoint", "/mnt"};
+        VERIFY_ARE_EQUAL(RunCommand(vm.get(), cmd), 0L);
+
+        // Unmount /mnt.
+        VERIFY_SUCCEEDED(WslUnmount(vm.get(), "/mnt"));
+        VERIFY_ARE_EQUAL(RunCommand(vm.get(), cmd), 32L);
+
+        // Verify that unmount fails now.
+        VERIFY_ARE_EQUAL(WslUnmount(vm.get(), "/mnt"), E_FAIL);
+
+        // Detach the disk
+        VERIFY_SUCCEEDED(WslDetachDisk(vm.get(), attachedDisk.ScsiLun));
+        VERIFY_IS_FALSE(blockDeviceExists(attachedDisk.ScsiLun));
+
+        // Verify that disk can't be detached twice
+        VERIFY_ARE_EQUAL(WslDetachDisk(vm.get(), attachedDisk.ScsiLun), HRESULT_FROM_WIN32(ERROR_NOT_FOUND));
+    }
+
     TEST_METHOD(CustomDmesgOutput)
     {
         WSL2_TEST_ONLY();