return nil, err
		}

		offset := ei.V2Obj.EcBSize * blockNum
		if offset >= m.size {
			return nil, fmt.Errorf("block %d out of range. offset %d > size %d", blockNum, offset, m.size)
		}
		m.blockOffset = offset
		m.blocks = (m.size + ei.V2Obj.EcBSize - 1) / ei.V2Obj.EcBSize
		if m.blocks > 0 {
			m.blocks--
		}
		if blockNum < m.blocks {
			m.size = ei.V2Obj.EcBSize
		} else {
			m.size -= offset
		}

				err = msgp.WrapError(err, "ErasureM")
				return
			}
		case "EcN":
			z.ErasureN, err = dc.ReadInt()
			if err != nil {
				err = msgp.WrapError(err, "ErasureN")
				return
			}
		case "EcBSize":
			z.ErasureBlockSize, err = dc.ReadInt64()
			if err != nil {
				err = msgp.WrapError(err, "ErasureBlockSize")
				return
			}
		case "EcIndex":
			z.ErasureIndex, err = dc.ReadInt()
			if err != nil {

	ErasureN           int               `json:"EcN" msg:"EcN"`                                  // Erasure parity blocks
	ErasureBlockSize   int64             `json:"EcBSize" msg:"EcBSize"`                          // Erasure block size
	ErasureIndex       int               `json:"EcIndex" msg:"EcIndex"`                          // Erasure disk index