s390/mm: implement __get_user_pages_fast()

	return 1;

}

/*

 * Like get_user_pages_fast() except its IRQ-safe in that it won't fall

 * back to the regular GUP.

 */

int __get_user_pages_fast(unsigned long start, int nr_pages, int write,

			  struct page **pages)

{

	struct mm_struct *mm = current->mm;

	unsigned long addr, len, end;

	unsigned long next, flags;

	pgd_t *pgdp, pgd;

	int nr = 0;

	start &= PAGE_MASK;

	addr = start;

	len = (unsigned long) nr_pages << PAGE_SHIFT;

	end = start + len;

	if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ,

					(void __user *)start, len)))

		return 0;

	local_irq_save(flags);

	pgdp = pgd_offset(mm, addr);

	do {

		pgd = *pgdp;

		barrier();

		next = pgd_addr_end(addr, end);

		if (pgd_none(pgd))

			break;

		if (!gup_pud_range(pgdp, pgd, addr, next, write, pages, &nr))

			break;

	} while (pgdp++, addr = next, addr != end);

	local_irq_restore(flags);

	return nr;

}

/**

 * get_user_pages_fast() - pin user pages in memory

 * @start:	starting user address