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Commit efec0abf authored by David Anderson's avatar David Anderson
Browse files

libdm, libsnapshot: Add a virtual interface for DeviceMapper. 

It is difficult to test libsnapshot failures because there is no way to
inject failure scenarios into the kernel's device-mapper. Exposing a
virtual interface will allow this kind of testing via dependency
injection.

Bug: 199785546
Test: builds, tests pass
Change-Id: I5add0c7e24f7fa2853114eaeda7c479eaa4e0552
parent 7f994f4c

fs_mgr/libdm/include/libdm/dm.h

+34 −17
Original line number Diff line number Diff line
@@ -55,7 +55,33 @@ static constexpr uint64_t kSectorSize = 512; 
// that prefix.

std::optional<std::string> ExtractBlockDeviceName(const std::string& path);



class DeviceMapper final {

// This interface is for testing purposes. See DeviceMapper proper for what these methods do.

class IDeviceMapper {

  public:

    virtual ~IDeviceMapper() {}



    struct TargetInfo {

        struct dm_target_spec spec;

        std::string data;

        TargetInfo() {}

        TargetInfo(const struct dm_target_spec& spec, const std::string& data)

            : spec(spec), data(data) {}



        bool IsOverflowSnapshot() const;

    };



    virtual bool CreateDevice(const std::string& name, const DmTable& table, std::string* path,

                              const std::chrono::milliseconds& timeout_ms) = 0;

    virtual DmDeviceState GetState(const std::string& name) const = 0;

    virtual bool LoadTableAndActivate(const std::string& name, const DmTable& table) = 0;

    virtual bool GetTableInfo(const std::string& name, std::vector<TargetInfo>* table) = 0;

    virtual bool GetTableStatus(const std::string& name, std::vector<TargetInfo>* table) = 0;

    virtual bool GetDmDevicePathByName(const std::string& name, std::string* path) = 0;

    virtual bool GetDeviceString(const std::string& name, std::string* dev) = 0;

    virtual bool DeleteDeviceIfExists(const std::string& name) = 0;

};



class DeviceMapper final : public IDeviceMapper {

  public:

    class DmBlockDevice final {

      public:
@@ -95,7 +121,7 @@ class DeviceMapper final { 
    // Removes a device mapper device with the given name.

    // Returns 'true' on success, false otherwise.

    bool DeleteDevice(const std::string& name);

    bool DeleteDeviceIfExists(const std::string& name);

    bool DeleteDeviceIfExists(const std::string& name) override;

    // Removes a device mapper device with the given name and waits for |timeout_ms| milliseconds

    // for the corresponding block device to be deleted.

    bool DeleteDevice(const std::string& name, const std::chrono::milliseconds& timeout_ms);
@@ -114,7 +140,7 @@ class DeviceMapper final { 
    // Returns the current state of the underlying device mapper device

    // with given name.

    // One of INVALID, SUSPENDED or ACTIVE.

    DmDeviceState GetState(const std::string& name) const;

    DmDeviceState GetState(const std::string& name) const override;



    // Puts the given device to the specified status, which must be either:

    // - SUSPENDED: suspend the device, or
@@ -158,7 +184,7 @@ class DeviceMapper final { 
    // not |path| is available. It is the caller's responsibility to ensure

    // there are no races.

    bool CreateDevice(const std::string& name, const DmTable& table, std::string* path,

                      const std::chrono::milliseconds& timeout_ms);

                      const std::chrono::milliseconds& timeout_ms) override;



    // Create a device and activate the given table, without waiting to acquire

    // a valid path. If the caller will use GetDmDevicePathByName(), it should
@@ -170,7 +196,7 @@ class DeviceMapper final { 
    // process. A device with the given name must already exist.

    //

    // Returns 'true' on success, false otherwise.

    bool LoadTableAndActivate(const std::string& name, const DmTable& table);

    bool LoadTableAndActivate(const std::string& name, const DmTable& table) override;



    // Returns true if a list of available device mapper targets registered in the kernel was

    // successfully read and stored in 'targets'. Returns 'false' otherwise.
@@ -216,7 +242,7 @@ class DeviceMapper final { 


    // Returns a major:minor string for the named device-mapper node, that can

    // be used as inputs to DmTargets that take a block device.

    bool GetDeviceString(const std::string& name, std::string* dev);

    bool GetDeviceString(const std::string& name, std::string* dev) override;



    // The only way to create a DeviceMapper object.

    static DeviceMapper& Instance();
@@ -231,20 +257,11 @@ class DeviceMapper final { 
    // contain one TargetInfo for each target in the table. If the device does

    // not exist, or there were too many targets, the call will fail and return

    // false.

    struct TargetInfo {

        struct dm_target_spec spec;

        std::string data;

        TargetInfo() {}

        TargetInfo(const struct dm_target_spec& spec, const std::string& data)

            : spec(spec), data(data) {}



        bool IsOverflowSnapshot() const;

    };

    bool GetTableStatus(const std::string& name, std::vector<TargetInfo>* table);

    bool GetTableStatus(const std::string& name, std::vector<TargetInfo>* table) override;



    // Identical to GetTableStatus, except also retrives the active table for the device

    // mapper device from the kernel.

    bool GetTableInfo(const std::string& name, std::vector<TargetInfo>* table);

    bool GetTableInfo(const std::string& name, std::vector<TargetInfo>* table) override;



    static std::string GetTargetType(const struct dm_target_spec& spec);

fs_mgr/libfs_avb/Android.bp

+1 −0
Original line number Diff line number Diff line
@@ -152,6 +152,7 @@ cc_test { 
    static_libs: [

        "libavb",

        "libdm",

        "libext2_uuid",

        "libfs_avb",

        "libfstab",

    ],

fs_mgr/libsnapshot/device_info.cpp

+4 −0
Original line number Diff line number Diff line
@@ -139,5 +139,9 @@ std::unique_ptr<android::fiemap::IImageManager> ISnapshotManager::IDeviceInfo::O 
    }

}



android::dm::IDeviceMapper& DeviceInfo::GetDeviceMapper() {

    return android::dm::DeviceMapper::Instance();

}



}  // namespace snapshot

}  // namespace android

fs_mgr/libsnapshot/device_info.h

+1 −0
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ class DeviceInfo final : public SnapshotManager::IDeviceInfo { 
    bool IsRecovery() const override;

    std::unique_ptr<IImageManager> OpenImageManager() const override;

    bool IsFirstStageInit() const override;

    android::dm::IDeviceMapper& GetDeviceMapper() override;



    void set_first_stage_init(bool value) { first_stage_init_ = value; }

fs_mgr/libsnapshot/include/libsnapshot/snapshot.h

+11 −2
Original line number Diff line number Diff line
@@ -110,6 +110,7 @@ class ISnapshotManager { 
        virtual bool IsTestDevice() const { return false; }

        virtual bool IsFirstStageInit() const = 0;

        virtual std::unique_ptr<IImageManager> OpenImageManager() const = 0;

        virtual android::dm::IDeviceMapper& GetDeviceMapper() = 0;



        // Helper method for implementing OpenImageManager.

        std::unique_ptr<IImageManager> OpenImageManager(const std::string& gsid_dir) const;
@@ -611,6 +612,14 @@ class SnapshotManager final : public ISnapshotManager { 
    MergeFailureCode CheckMergeConsistency(LockedFile* lock, const std::string& name,

                                           const SnapshotStatus& update_status);



    // Get status or table information about a device-mapper node with a single target.

    enum class TableQuery {

        Table,

        Status,

    };

    bool GetSingleTarget(const std::string& dm_name, TableQuery query,

                         android::dm::DeviceMapper::TargetInfo* target);



    // Interact with status files under /metadata/ota/snapshots.

    bool WriteSnapshotStatus(LockedFile* lock, const SnapshotStatus& status);

    bool ReadSnapshotStatus(LockedFile* lock, const std::string& name, SnapshotStatus* status);
@@ -773,9 +782,9 @@ class SnapshotManager final : public ISnapshotManager { 
    bool DeleteDeviceIfExists(const std::string& name,

                              const std::chrono::milliseconds& timeout_ms = {});



    std::string gsid_dir_;

    std::string metadata_dir_;

    android::dm::IDeviceMapper& dm_;

    std::unique_ptr<IDeviceInfo> device_;

    std::string metadata_dir_;

    std::unique_ptr<IImageManager> images_;

    bool use_first_stage_snapuserd_ = false;

    bool in_factory_data_reset_ = false;