dax: Use new dax zero page method for zeroing a page

	return ret;

}

static bool dax_range_is_aligned(struct block_device *bdev,

				 unsigned int offset, unsigned int length)

{

	unsigned short sector_size = bdev_logical_block_size(bdev);

	if (!IS_ALIGNED(offset, sector_size))

		return false;

	if (!IS_ALIGNED(length, sector_size))

		return false;

	return true;

}

int __dax_zero_page_range(struct block_device *bdev,

		struct dax_device *dax_dev, sector_t sector,

		unsigned int offset, unsigned int size)

{

	if (dax_range_is_aligned(bdev, offset, size)) {

		sector_t start_sector = sector + (offset >> 9);

		return blkdev_issue_zeroout(bdev, start_sector,

				size >> 9, GFP_NOFS, 0);

	} else {

	pgoff_t pgoff;

	long rc, id;

	void *kaddr;

	bool page_aligned = false;

	if (IS_ALIGNED(sector << SECTOR_SHIFT, PAGE_SIZE) &&

	    IS_ALIGNED(size, PAGE_SIZE))

		page_aligned = true;

	rc = bdev_dax_pgoff(bdev, sector, PAGE_SIZE, &pgoff);

	if (rc)

		return rc;

	id = dax_read_lock();

	if (page_aligned)

		rc = dax_zero_page_range(dax_dev, pgoff, size >> PAGE_SHIFT);

	else

		rc = dax_direct_access(dax_dev, pgoff, 1, &kaddr, NULL);

	if (rc < 0) {

		dax_read_unlock(id);

		return rc;

	}

	if (!page_aligned) {

		memset(kaddr + offset, 0, size);

		dax_flush(dax_dev, kaddr + offset, size);

		dax_read_unlock(id);

	}

	dax_read_unlock(id);

	return 0;

}

EXPORT_SYMBOL_GPL(__dax_zero_page_range);