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Commit 03e80345 authored by Akilesh Kailash's avatar Akilesh Kailash
Browse files

libsnapshot: No transition of snapuserd during second stage init 



When there is a transition of daemon from selinux stage, we observe
intermittent hangs during OTA. This is a workaround wherein
we don't do the transition and allow the daemon to continue which
was spawned during selinux stage.

Bug: 179331261
Test: Incremental OTA, full OTA on pixel
Signed-off-by: default avatarAkilesh Kailash <akailash@google.com>
Change-Id: I622a0ed8afcd404bac4919b1de00728de2c12eaf
parent cb9e1dec

fs_mgr/libsnapshot/snapshot.cpp

+30 −17
Original line number Diff line number Diff line
@@ -1234,6 +1234,25 @@ bool SnapshotManager::OnSnapshotMergeComplete(LockedFile* lock, const std::strin 
    return true;

}



static bool DeleteDmDevice(const std::string& name, const std::chrono::milliseconds& timeout_ms) {

    auto start = std::chrono::steady_clock::now();

    auto& dm = DeviceMapper::Instance();

    while (true) {

        if (dm.DeleteDeviceIfExists(name)) {

            break;

        }

        auto now = std::chrono::steady_clock::now();

        auto elapsed = std::chrono::duration_cast<std::chrono::milliseconds>(now - start);

        if (elapsed >= timeout_ms) {

            LOG(ERROR) << "DeleteDevice timeout: " << name;

            return false;

        }

        std::this_thread::sleep_for(250ms);

    }



    return true;

}



bool SnapshotManager::CollapseSnapshotDevice(const std::string& name,

                                             const SnapshotStatus& status) {

    auto& dm = DeviceMapper::Instance();
@@ -1292,10 +1311,11 @@ bool SnapshotManager::CollapseSnapshotDevice(const std::string& name, 
    if (!dm.DeleteDeviceIfExists(base_name)) {

        LOG(ERROR) << "Unable to delete base device for snapshot: " << base_name;

    }

    auto source_name = GetSourceDeviceName(name);

    if (!dm.DeleteDeviceIfExists(source_name)) {

        LOG(ERROR) << "Unable to delete source device for snapshot: " << source_name;



    if (!DeleteDmDevice(GetSourceDeviceName(name), 4000ms)) {

        LOG(ERROR) << "Unable to delete source device for snapshot: " << GetSourceDeviceName(name);

    }



    return true;

}
@@ -1387,9 +1407,6 @@ bool SnapshotManager::PerformInitTransition(InitTransition transition, 
        }



        auto misc_name = user_cow_name;

        if (transition == InitTransition::SELINUX_DETACH) {

            misc_name += "-selinux";

        }



        DmTable table;

        table.Emplace<DmTargetUser>(0, target.spec.length, misc_name);
@@ -2122,15 +2139,12 @@ bool SnapshotManager::UnmapCowDevices(LockedFile* lock, const std::string& name) 
    CHECK(lock);

    if (!EnsureImageManager()) return false;



    auto& dm = DeviceMapper::Instance();



    if (UpdateUsesCompression(lock) && !UnmapDmUserDevice(name)) {

        return false;

    }



    auto cow_name = GetCowName(name);

    if (!dm.DeleteDeviceIfExists(cow_name)) {

        LOG(ERROR) << "Cannot unmap " << cow_name;

    if (!DeleteDmDevice(GetCowName(name), 4000ms)) {

        LOG(ERROR) << "Cannot unmap: " << GetCowName(name);

        return false;

    }
@@ -2155,13 +2169,12 @@ bool SnapshotManager::UnmapDmUserDevice(const std::string& snapshot_name) { 
        return false;

    }



    if (!EnsureSnapuserdConnected()) {

        return false;

    }

    if (EnsureSnapuserdConnected()) {

        if (!snapuserd_client_->WaitForDeviceDelete(dm_user_name)) {

            LOG(ERROR) << "Failed to wait for " << dm_user_name << " control device to delete";

            return false;

        }

    }



    // Ensure the control device is gone so we don't run into ABA problems.

    auto control_device = "/dev/dm-user/" + dm_user_name;

fs_mgr/libsnapshot/snapuserd.cpp

+1 −1
Original line number Diff line number Diff line
@@ -534,7 +534,7 @@ bool Snapuserd::ReadMetadata() { 
    bool prev_copy_op = false;

    bool metadata_found = false;



    SNAP_LOG(DEBUG) << "ReadMetadata Start...";

    SNAP_LOG(DEBUG) << "ReadMetadata: Parsing cow file";



    if (!reader_->Parse(cow_fd_)) {

        SNAP_LOG(ERROR) << "Failed to parse";

fs_mgr/libsnapshot/snapuserd.h

+5 −0
Original line number Diff line number Diff line
@@ -70,6 +70,11 @@ class Snapuserd final { 
    const std::string& GetMiscName() { return misc_name_; }

    uint64_t GetNumSectors() { return num_sectors_; }

    bool IsAttached() const { return ctrl_fd_ >= 0; }

    void CloseFds() {

        ctrl_fd_ = {};

        cow_fd_ = {};

        backing_store_fd_ = {};

    }



  private:

    bool DmuserReadRequest();

fs_mgr/libsnapshot/snapuserd_server.cpp

+2 −0
Original line number Diff line number Diff line
@@ -210,6 +210,8 @@ void SnapuserdServer::RunThread(std::shared_ptr<DmUserHandler> handler) { 
        }

    }



    handler->snapuserd()->CloseFds();



    auto misc_name = handler->misc_name();

    LOG(INFO) << "Handler thread about to exit: " << misc_name;

init/init.cpp

+0 −32
Original line number Diff line number Diff line
@@ -723,37 +723,6 @@ void SendLoadPersistentPropertiesMessage() { 
    }

}



static Result<void> TransitionSnapuserdAction(const BuiltinArguments&) {

    if (!SnapshotManager::IsSnapshotManagerNeeded() ||

        !android::base::GetBoolProperty(android::snapshot::kVirtualAbCompressionProp, false)) {

        return {};

    }



    auto sm = SnapshotManager::New();

    if (!sm) {

        LOG(FATAL) << "Failed to create SnapshotManager, will not transition snapuserd";

        return {};

    }



    ServiceList& service_list = ServiceList::GetInstance();

    auto svc = service_list.FindService("snapuserd");

    if (!svc) {

        LOG(FATAL) << "Failed to find snapuserd service, aborting transition";

        return {};

    }

    svc->Start();

    svc->SetShutdownCritical();



    if (!sm->PerformSecondStageInitTransition()) {

        LOG(FATAL) << "Failed to transition snapuserd to second-stage";

    }



    if (auto pid = GetSnapuserdFirstStagePid()) {

        KillFirstStageSnapuserd(pid.value());

    }

    return {};

}



int SecondStageMain(int argc, char** argv) {

    if (REBOOT_BOOTLOADER_ON_PANIC) {

        InstallRebootSignalHandlers();
@@ -900,7 +869,6 @@ int SecondStageMain(int argc, char** argv) { 


    // Queue an action that waits for coldboot done so we know ueventd has set up all of /dev...

    am.QueueBuiltinAction(wait_for_coldboot_done_action, "wait_for_coldboot_done");

    am.QueueBuiltinAction(TransitionSnapuserdAction, "TransitionSnapuserd");

    // ... so that we can start queuing up actions that require stuff from /dev.

    am.QueueBuiltinAction(SetMmapRndBitsAction, "SetMmapRndBits");

    Keychords keychords;