Delete in Cloud Files API stopped working on Windows 21H1

Question

I am creating virtual drive using Windows Cloud Filter API. The delete callback stopped working as expected on Windows Home 21H1 19043.1165 (cldflt.sys 10.0.19041.1110). If I return an error code from the CF_CALLBACK_TYPE_NOTIFY_DELETE, the dehydrated placeholder is deleted anyway, regardless of the error code that I return:

void CALLBACK FakeCloudProvider::OnNotifyDelete(
    _In_ CONST CF_CALLBACK_INFO* callbackInfo,
    _In_ CONST CF_CALLBACK_PARAMETERS* callbackParameters)
{
    CF_OPERATION_INFO opInfo = { 0 };
    
    opInfo.StructSize = sizeof(CF_OPERATION_INFO);
    opInfo.Type = CF_OPERATION_TYPE_ACK_DELETE;
    opInfo.ConnectionKey = callbackInfo->ConnectionKey;
    opInfo.TransferKey = callbackInfo->TransferKey;
    opInfo.CorrelationVector = callbackInfo->CorrelationVector;
    opInfo.RequestKey = callbackInfo->RequestKey;

    CF_SYNC_STATUS_MSG* syncStatus = new CF_SYNC_STATUS_MSG;
    syncStatus->Code = STATUS_FILE_LOCKED_WITH_WRITERS;
    syncStatus->SetMsg(L"MY TEST");

    opInfo.SyncStatus = syncStatus;
    
    CF_OPERATION_PARAMETERS params = {0};
    params.ParamSize = sizeof(CF_OPERATION_PARAMETERS);
    params.AckDelete.Flags = CF_OPERATION_ACK_DELETE_FLAG_NONE;

    // I have also tested many other error codes.
    params.AckDelete.CompletionStatus = STATUS_FILE_LOCKED_WITH_WRITERS; 
    
    HRESULT res = CfExecute(&opInfo, &params);
}

I have tested delete from both Windows Explorer and from command prompt on Windows 21H1. The result is identical - placeholder is deleted.

I have also retested delete on the older version - Windows 10 Pro 1909 (18363.1556) (cldflt.sys 10.0.18362.1533) and everything worked as expected - if I return an error from the delete callback the file is NOT deleted.

I guess this is a bug in latest Windows update. Was anybody able to find a solution for this behavior?

Answer 1

This is a known issue in Windows cloud filter API. It affects Windows 20H1 and later versions. Here is the discussion about this issue: https://learn.microsoft.com/en-us/answers/questions/75240/bug-report-cfapi-ackdelete-borken-on-win10-2004.html There is no any real solution for now as far as I know. Returning any specific error code does not help. The only possible solution would be recreating the deleted file in the local file system during synchronization at some later time.

Answer 2

Just tested on Windows 11 (build 10.0.22000.194), it seems this bug has finally been fixed.