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Commit 5b983274 authored by David Anderson's avatar David Anderson Committed by Gerrit Code Review
Browse files

Merge changes I5e93fcbf,I9d4c8bcf,Icd580aae,I7b2399a4 

* changes:
  libsnapshot: Implement merge flow.
  libsnapshot: Unmap COW devices when deleting snapshots.
  libsnapshot: Eliminate per-snapshot flocks.
  libsnapshot: Improve first test-run and test cleanup.
parents 2edc7a51 5312c466

fs_mgr/libdm/include/libdm/dm.h

+1 −0
Original line number Diff line number Diff line
@@ -197,6 +197,7 @@ class DeviceMapper final { 
    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) {}

    };

fs_mgr/libsnapshot/include/libsnapshot/snapshot.h

+65 −10
Original line number Diff line number Diff line
@@ -22,7 +22,8 @@ 
#include <vector>



#include <android-base/unique_fd.h>

#include <libdm/dm_target.h>

#include <libdm/dm.h>

#include <libfiemap/image_manager.h>



#ifndef FRIEND_TEST

#define FRIEND_TEST(test_set_name, individual_test) \
@@ -38,7 +39,7 @@ class IImageManager; 


namespace snapshot {



enum class UpdateState {

enum class UpdateState : unsigned int {

    // No update or merge is in progress.

    None,
@@ -51,6 +52,10 @@ enum class UpdateState { 
    // The kernel is merging in the background.

    Merging,



    // Post-merge cleanup steps could not be completed due to a transient

    // error, but the next reboot will finish any pending operations.

    MergeNeedsReboot,



    // Merging is complete, and needs to be acknowledged.

    MergeCompleted,
@@ -94,8 +99,23 @@ class SnapshotManager final { 


    // Wait for the current merge to finish, then perform cleanup when it

    // completes. It is necessary to call this after InitiateMerge(), or when

    // a merge is detected for the first time after boot.

    bool WaitForMerge();

    // a merge state is detected during boot.

    //

    // Note that after calling WaitForMerge(), GetUpdateState() may still return

    // that a merge is in progress:

    //   MergeFailed indicates that a fatal error occurred. WaitForMerge() may

    //   called any number of times again to attempt to make more progress, but

    //   we do not expect it to succeed if a catastrophic error occurred.

    //

    //   MergeNeedsReboot indicates that the merge has completed, but cleanup

    //   failed. This can happen if for some reason resources were not closed

    //   properly. In this case another reboot is needed before we can take

    //   another OTA. However, WaitForMerge() can be called again without

    //   rebooting, to attempt to finish cleanup anyway.

    //

    //   MergeCompleted indicates that the update has fully completed.

    //   GetUpdateState will return None, and a new update can begin.

    UpdateState WaitForMerge();



    // Find the status of the current update, if any.

    //
@@ -109,9 +129,14 @@ class SnapshotManager final { 
    FRIEND_TEST(SnapshotTest, CreateSnapshot);

    FRIEND_TEST(SnapshotTest, MapSnapshot);

    FRIEND_TEST(SnapshotTest, MapPartialSnapshot);

    FRIEND_TEST(SnapshotTest, NoMergeBeforeReboot);

    FRIEND_TEST(SnapshotTest, Merge);

    FRIEND_TEST(SnapshotTest, MergeCannotRemoveCow);

    friend class SnapshotTest;



    using DmTargetSnapshot = android::dm::DmTargetSnapshot;

    using IImageManager = android::fiemap::IImageManager;

    using TargetInfo = android::dm::DeviceMapper::TargetInfo;



    explicit SnapshotManager(IDeviceInfo* info);
@@ -126,16 +151,18 @@ class SnapshotManager final { 
    // this. It also serves as a proof-of-lock for some functions.

    class LockedFile final {

      public:

        LockedFile(const std::string& path, android::base::unique_fd&& fd)

            : path_(path), fd_(std::move(fd)) {}

        LockedFile(const std::string& path, android::base::unique_fd&& fd, int lock_mode)

            : path_(path), fd_(std::move(fd)), lock_mode_(lock_mode) {}

        ~LockedFile();



        const std::string& path() const { return path_; }

        int fd() const { return fd_; }

        int lock_mode() const { return lock_mode_; }



      private:

        std::string path_;

        android::base::unique_fd fd_;

        int lock_mode_;

    };

    std::unique_ptr<LockedFile> OpenFile(const std::string& file, int open_flags, int lock_flags);

    bool Truncate(LockedFile* file);
@@ -189,6 +216,7 @@ class SnapshotManager final { 
    std::unique_ptr<LockedFile> LockExclusive();

    UpdateState ReadUpdateState(LockedFile* file);

    bool WriteUpdateState(LockedFile* file, UpdateState state);

    std::string GetStateFilePath() const;



    // This state is persisted per-snapshot in /metadata/ota/snapshots/.

    struct SnapshotStatus {
@@ -200,11 +228,38 @@ class SnapshotManager final { 
        uint64_t metadata_sectors = 0;

    };



    // Helpers for merging.

    bool SwitchSnapshotToMerge(LockedFile* lock, const std::string& name);

    bool RewriteSnapshotDeviceTable(const std::string& dm_name);

    bool MarkSnapshotMergeCompleted(LockedFile* snapshot_lock, const std::string& snapshot_name);

    void AcknowledgeMergeSuccess(LockedFile* lock);

    void AcknowledgeMergeFailure();



    // Note that these require the name of the device containing the snapshot,

    // which may be the "inner" device. Use GetsnapshotDeviecName().

    bool QuerySnapshotStatus(const std::string& dm_name, std::string* target_type,

                             DmTargetSnapshot::Status* status);

    bool IsSnapshotDevice(const std::string& dm_name, TargetInfo* target = nullptr);



    // Internal callback for when merging is complete.

    bool OnSnapshotMergeComplete(LockedFile* lock, const std::string& name,

                                 const SnapshotStatus& status);

    bool CollapseSnapshotDevice(const std::string& name, const SnapshotStatus& status);



    // Only the following UpdateStates are used here:

    //   UpdateState::Merging

    //   UpdateState::MergeCompleted

    //   UpdateState::MergeFailed

    //   UpdateState::MergeNeedsReboot

    UpdateState CheckMergeState();

    UpdateState CheckMergeState(LockedFile* lock);

    UpdateState CheckTargetMergeState(LockedFile* lock, const std::string& name);



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

    std::unique_ptr<LockedFile> OpenSnapshotStatusFile(const std::string& name, int open_flags,

                                                       int lock_flags);

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

    bool ReadSnapshotStatus(LockedFile* file, SnapshotStatus* status);

    bool WriteSnapshotStatus(LockedFile* lock, const std::string& name,

                             const SnapshotStatus& status);

    bool ReadSnapshotStatus(LockedFile* lock, const std::string& name, SnapshotStatus* status);

    std::string GetSnapshotStatusFilePath(const std::string& name);



    // Return the name of the device holding the "snapshot" or "snapshot-merge"

    // target. This may not be the final device presented via MapSnapshot(), if

fs_mgr/libsnapshot/snapshot.cpp

+589 −48

File changed.

Preview size limit exceeded, changes collapsed.

fs_mgr/libsnapshot/snapshot_test.cpp

+155 −7
Original line number Diff line number Diff line
@@ -22,13 +22,20 @@ 
#include <chrono>

#include <iostream>



#include <android-base/file.h>

#include <android-base/properties.h>

#include <android-base/strings.h>

#include <android-base/unique_fd.h>

#include <gtest/gtest.h>

#include <libdm/dm.h>

#include <libfiemap/image_manager.h>



namespace android {

namespace snapshot {



using android::base::unique_fd;

using android::dm::DeviceMapper;

using android::dm::DmDeviceState;

using namespace std::chrono_literals;

using namespace std::string_literals;
@@ -48,12 +55,15 @@ std::unique_ptr<SnapshotManager> sm; 
TestDeviceInfo* test_device = nullptr;



class SnapshotTest : public ::testing::Test {

  public:

    SnapshotTest() : dm_(DeviceMapper::Instance()) {}



  protected:

    void SetUp() override {

        test_device->set_is_running_snapshot(false);



        if (sm->GetUpdateState() != UpdateState::None) {

            ASSERT_TRUE(sm->CancelUpdate());

            CleanupTestArtifacts();

        }

        ASSERT_TRUE(sm->BeginUpdate());

        ASSERT_TRUE(sm->EnsureImageManager());
@@ -65,13 +75,32 @@ class SnapshotTest : public ::testing::Test { 
    void TearDown() override {

        lock_ = nullptr;



        if (sm->GetUpdateState() != UpdateState::None) {

            ASSERT_TRUE(sm->CancelUpdate());

        CleanupTestArtifacts();

    }



    void CleanupTestArtifacts() {

        // Normally cancelling inside a merge is not allowed. Since these

        // are tests, we don't care, destroy everything that might exist.

        std::vector<std::string> snapshots = {"test-snapshot"};

        for (const auto& snapshot : snapshots) {

            DeleteSnapshotDevice(snapshot);

            temp_images_.emplace_back(snapshot + "-cow");



            auto status_file = sm->GetSnapshotStatusFilePath(snapshot);

            android::base::RemoveFileIfExists(status_file);

        }



        // Remove all images.

        temp_images_.emplace_back("test-snapshot-cow");

        for (const auto& temp_image : temp_images_) {

            image_manager_->UnmapImageDevice(temp_image);

            image_manager_->DeleteBackingImage(temp_image);

        }



        if (sm->GetUpdateState() != UpdateState::None) {

            auto state_file = sm->GetStateFilePath();

            unlink(state_file.c_str());

        }

    }



    bool AcquireLock() {
@@ -87,6 +116,17 @@ class SnapshotTest : public ::testing::Test { 
        return image_manager_->MapImageDevice(name, 10s, path);

    }



    bool DeleteSnapshotDevice(const std::string& snapshot) {

        if (dm_.GetState(snapshot) != DmDeviceState::INVALID) {

            if (!dm_.DeleteDevice(snapshot)) return false;

        }

        if (dm_.GetState(snapshot + "-inner") != DmDeviceState::INVALID) {

            if (!dm_.DeleteDevice(snapshot + "-inner")) return false;

        }

        return true;

    }



    DeviceMapper& dm_;

    std::unique_ptr<SnapshotManager::LockedFile> lock_;

    std::vector<std::string> temp_images_;

    android::fiemap::IImageManager* image_manager_ = nullptr;
@@ -106,11 +146,8 @@ TEST_F(SnapshotTest, CreateSnapshot) { 


    // Scope so delete can re-acquire the snapshot file lock.

    {

        auto file = sm->OpenSnapshotStatusFile("test-snapshot", O_RDONLY, LOCK_SH);

        ASSERT_NE(file, nullptr);



        SnapshotManager::SnapshotStatus status;

        ASSERT_TRUE(sm->ReadSnapshotStatus(file.get(), &status));

        ASSERT_TRUE(sm->ReadSnapshotStatus(lock_.get(), "test-snapshot", &status));

        ASSERT_EQ(status.state, "created");

        ASSERT_EQ(status.device_size, kDeviceSize);

        ASSERT_EQ(status.snapshot_size, kDeviceSize);
@@ -151,6 +188,117 @@ TEST_F(SnapshotTest, MapPartialSnapshot) { 
    ASSERT_TRUE(android::base::StartsWith(snap_device, "/dev/block/dm-"));

}



TEST_F(SnapshotTest, NoMergeBeforeReboot) {

    ASSERT_TRUE(AcquireLock());



    // Set the state to Unverified, as if we finished an update.

    ASSERT_TRUE(sm->WriteUpdateState(lock_.get(), UpdateState::Unverified));



    // Release the lock.

    lock_ = nullptr;



    // Merge should fail, since we didn't mark the device as rebooted.

    ASSERT_FALSE(sm->InitiateMerge());

}



TEST_F(SnapshotTest, Merge) {

    ASSERT_TRUE(AcquireLock());



    static const uint64_t kDeviceSize = 1024 * 1024;

    ASSERT_TRUE(sm->CreateSnapshot(lock_.get(), "test-snapshot", kDeviceSize, kDeviceSize,

                                   kDeviceSize));



    std::string base_device, snap_device;

    ASSERT_TRUE(CreateTempDevice("base-device", kDeviceSize, &base_device));

    ASSERT_TRUE(sm->MapSnapshot(lock_.get(), "test-snapshot", base_device, 10s, &snap_device));



    std::string test_string = "This is a test string.";

    {

        unique_fd fd(open(snap_device.c_str(), O_RDWR | O_CLOEXEC | O_SYNC));

        ASSERT_GE(fd, 0);

        ASSERT_TRUE(android::base::WriteFully(fd, test_string.data(), test_string.size()));

    }



    // Note: we know the name of the device is test-snapshot because we didn't

    // request a linear segment.

    DeviceMapper::TargetInfo target;

    ASSERT_TRUE(sm->IsSnapshotDevice("test-snapshot", &target));

    ASSERT_EQ(DeviceMapper::GetTargetType(target.spec), "snapshot");



    // Set the state to Unverified, as if we finished an update.

    ASSERT_TRUE(sm->WriteUpdateState(lock_.get(), UpdateState::Unverified));



    // Release the lock.

    lock_ = nullptr;



    test_device->set_is_running_snapshot(true);

    ASSERT_TRUE(sm->InitiateMerge());



    // The device should have been switched to a snapshot-merge target.

    ASSERT_TRUE(sm->IsSnapshotDevice("test-snapshot", &target));

    ASSERT_EQ(DeviceMapper::GetTargetType(target.spec), "snapshot-merge");



    // We should not be able to cancel an update now.

    ASSERT_FALSE(sm->CancelUpdate());



    ASSERT_EQ(sm->WaitForMerge(), UpdateState::MergeCompleted);

    ASSERT_EQ(sm->GetUpdateState(), UpdateState::None);



    // The device should no longer be a snapshot or snapshot-merge.

    ASSERT_FALSE(sm->IsSnapshotDevice("test-snapshot"));



    // Test that we can read back the string we wrote to the snapshot.

    unique_fd fd(open(base_device.c_str(), O_RDONLY | O_CLOEXEC));

    ASSERT_GE(fd, 0);



    std::string buffer(test_string.size(), '\0');

    ASSERT_TRUE(android::base::ReadFully(fd, buffer.data(), buffer.size()));

    ASSERT_EQ(test_string, buffer);

}



TEST_F(SnapshotTest, MergeCannotRemoveCow) {

    ASSERT_TRUE(AcquireLock());



    static const uint64_t kDeviceSize = 1024 * 1024;

    ASSERT_TRUE(sm->CreateSnapshot(lock_.get(), "test-snapshot", kDeviceSize, kDeviceSize,

                                   kDeviceSize));



    std::string base_device, snap_device;

    ASSERT_TRUE(CreateTempDevice("base-device", kDeviceSize, &base_device));

    ASSERT_TRUE(sm->MapSnapshot(lock_.get(), "test-snapshot", base_device, 10s, &snap_device));



    // Keep an open handle to the cow device. This should cause the merge to

    // be incomplete.

    auto cow_path = android::base::GetProperty("gsid.mapped_image.test-snapshot-cow", "");

    unique_fd fd(open(cow_path.c_str(), O_RDONLY | O_CLOEXEC));

    ASSERT_GE(fd, 0);



    // Set the state to Unverified, as if we finished an update.

    ASSERT_TRUE(sm->WriteUpdateState(lock_.get(), UpdateState::Unverified));



    // Release the lock.

    lock_ = nullptr;



    test_device->set_is_running_snapshot(true);

    ASSERT_TRUE(sm->InitiateMerge());



    // COW cannot be removed due to open fd, so expect a soft failure.

    ASSERT_EQ(sm->WaitForMerge(), UpdateState::MergeNeedsReboot);



    // Forcefully delete the snapshot device, so it looks like we just rebooted.

    ASSERT_TRUE(DeleteSnapshotDevice("test-snapshot"));



    // Map snapshot should fail now, because we're in a merge-complete state.

    ASSERT_TRUE(AcquireLock());

    ASSERT_FALSE(sm->MapSnapshot(lock_.get(), "test-snapshot", base_device, 10s, &snap_device));



    // Release everything and now the merge should complete.

    fd = {};

    lock_ = nullptr;



    ASSERT_EQ(sm->WaitForMerge(), UpdateState::MergeCompleted);

}



}  // namespace snapshot

}  // namespace android