ib_umem_copy_from
ret = ib_umem_copy_from(buffer, umem, offset, first_copy_length);
ret = ib_umem_copy_from(buffer + first_copy_length, umem, wq->offset,
EXPORT_SYMBOL(ib_umem_copy_from);
int ib_umem_copy_from(void *dst, struct ib_umem *umem, size_t offset,