rs = fc->fcp->slices_per_group - fc->fcp->data_slices_per_group;
ret = num_slices(vsst->header_len, fc->mps - FEC_HEADER_SIZE, rs);
if (ret < 0)
rs = fc->fcp->slices_per_group - fc->fcp->data_slices_per_group;
ret = num_slices(vsst->header_len, fc->mps - FEC_HEADER_SIZE, rs);
if (ret < 0)