async_xor
EXPORT_SYMBOL_GPL(async_xor);
tx = async_xor(dest, blocks, 0, count, bytes, &submit);
async_xor(dst_page, src_pages, pl_offset, 2, this_step, &submit);
tx = async_xor(sh->ppl_page, srcs, 0, count, PAGE_SIZE,
tx = async_xor(page1, xor_srcs, 0, 2, size, &submit);
async_xor(struct page *dest, struct page **src_list, unsigned int offset,