Ceph » rgw

the relevant block of code in RGWPutObj::execute():

    /* do we need this operation to be synchronous? if we're dealing with an object with immutable
     * head, e.g., multipart object we need to make sure we're the first one writing to this object
     */
    bool need_to_wait = (ofs == 0) && multipart;

    bufferlist orig_data;

    if (need_to_wait) {
      orig_data = data;
    }

    op_ret = put_data_and_throttle(filter, data, ofs, need_to_wait);
    if (op_ret < 0) {
      if (!need_to_wait || op_ret != -EEXIST) {
        ldout(s->cct, 20) << "processor->thottle_data() returned ret=" 
                          << op_ret << dendl;
        goto done;
      }
      /* need_to_wait == true and op_ret == -EEXIST */
      ldout(s->cct, 5) << "NOTICE: processor->throttle_data() returned -EEXIST, need to restart write" << dendl;

for uncompressed objects, the first rados write will always start at ofs=0. when compression is enabled, we fit more than one chunk into the first rados write and will see an ofs > 0. this leads to need_to_wait=false, where the EEXIST error is treated as fatal instead of restarting the write to a different object

attached a python script to reproduce this failure:

~/ceph/build $ ./resend_part.py cosbench-0.4.2.c4.tar                                                                                                            
Traceback (most recent call last):          
  File "./resend_part.py", line 34, in <module>                                         
    p = part.upload(Body=body)              
  File "/usr/lib/python2.7/site-packages/boto3/resources/factory.py", line 520, in do_action                                                                                     
    response = action(self, *args, **kwargs)                                            
  File "/usr/lib/python2.7/site-packages/boto3/resources/action.py", line 83, in __call__                                                                                        
    response = getattr(parent.meta.client, operation_name)(**params)                    
  File "/usr/lib/python2.7/site-packages/botocore/client.py", line 317, in _api_call    
    return self._make_api_call(operation_name, kwargs)                                  
  File "/usr/lib/python2.7/site-packages/botocore/client.py", line 615, in _make_api_call                                                                                        
    raise error_class(parsed_response, operation_name)                                  
botocore.errorfactory.BucketAlreadyExists: An error occurred (BucketAlreadyExists) when calling the UploadPart operation: Unknown

https://github.com/ceph/ceph/pull/23033