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Commit 95b3d2e6 authored by David Anderson's avatar David Anderson Committed by Automerger Merge Worker
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Merge "snapuserd: Fix race condition in MergeWorker::WaitForMergeBegin." into... 

Merge "snapuserd: Fix race condition in MergeWorker::WaitForMergeBegin." into main am: c718295a am: 90770499 am: d17c3ebb am: 0e051700

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2701653



Change-Id: I59d44fcd72c13fb9b6a954330d3a45bda966e83f
Signed-off-by: default avatarAutomerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
parents 75796fc7 0e051700

fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_transitions.cpp

+18 −21
Original line number Diff line number Diff line
@@ -189,36 +189,33 @@ void SnapshotHandler::InitiateMerge() { 
    cv.notify_all();

}



static inline bool IsMergeBeginError(MERGE_IO_TRANSITION io_state) {

    return io_state == MERGE_IO_TRANSITION::READ_AHEAD_FAILURE ||

           io_state == MERGE_IO_TRANSITION::IO_TERMINATED;

}



// Invoked by Merge thread - Waits on RA thread to resume merging. Will

// be waken up RA thread.

bool SnapshotHandler::WaitForMergeBegin() {

    {

    std::unique_lock<std::mutex> lock(lock_);

        while (!MergeInitiated()) {

            cv.wait(lock);



            if (io_state_ == MERGE_IO_TRANSITION::READ_AHEAD_FAILURE ||

                io_state_ == MERGE_IO_TRANSITION::IO_TERMINATED) {

    cv.wait(lock, [this]() -> bool { return MergeInitiated() || IsMergeBeginError(io_state_); });



    if (IsMergeBeginError(io_state_)) {

        SNAP_LOG(ERROR) << "WaitForMergeBegin failed with state: " << io_state_;

        return false;

    }

        }



        while (!(io_state_ == MERGE_IO_TRANSITION::MERGE_BEGIN ||

                 io_state_ == MERGE_IO_TRANSITION::READ_AHEAD_FAILURE ||

                 io_state_ == MERGE_IO_TRANSITION::IO_TERMINATED)) {

            cv.wait(lock);

        }

    cv.wait(lock, [this]() -> bool {

        return io_state_ == MERGE_IO_TRANSITION::MERGE_BEGIN || IsMergeBeginError(io_state_);

    });



        if (io_state_ == MERGE_IO_TRANSITION::READ_AHEAD_FAILURE ||

            io_state_ == MERGE_IO_TRANSITION::IO_TERMINATED) {

    if (IsMergeBeginError(io_state_)) {

        SNAP_LOG(ERROR) << "WaitForMergeBegin failed with state: " << io_state_;

        return false;

    }



    return true;

}

}



// Invoked by RA thread - Flushes the RA block to scratch space if necessary

// and then notifies the merge thread to resume merging