drm/udl: use gem get/put page helpers

static int udl_gem_get_pages(struct udl_gem_object *obj, gfp_t gfpmask)

{

	int page_count, i;

	struct page *page;

	struct inode *inode;

	struct address_space *mapping;

	struct page **pages;

	if (obj->pages)

		return 0;

	page_count = obj->base.size / PAGE_SIZE;

	BUG_ON(obj->pages != NULL);

	obj->pages = drm_malloc_ab(page_count, sizeof(struct page *));

	if (obj->pages == NULL)

		return -ENOMEM;

	inode = file_inode(obj->base.filp);

	mapping = inode->i_mapping;

	gfpmask |= mapping_gfp_mask(mapping);

	pages = drm_gem_get_pages(&obj->base, gfpmask);

	if (IS_ERR(pages))

		return PTR_ERR(pages);

	for (i = 0; i < page_count; i++) {

		page = shmem_read_mapping_page_gfp(mapping, i, gfpmask);

		if (IS_ERR(page))

			goto err_pages;

		obj->pages[i] = page;

	}

	obj->pages = pages;

	return 0;

err_pages:

	while (i--)

		page_cache_release(obj->pages[i]);

	drm_free_large(obj->pages);

	obj->pages = NULL;

	return PTR_ERR(page);

}

static void udl_gem_put_pages(struct udl_gem_object *obj)

{

	int page_count = obj->base.size / PAGE_SIZE;

	int i;

	if (obj->base.import_attach) {

		drm_free_large(obj->pages);

		obj->pages = NULL;

		return;

	}

	for (i = 0; i < page_count; i++)

		page_cache_release(obj->pages[i]);

	drm_free_large(obj->pages);

	drm_gem_put_pages(&obj->base, obj->pages, false, false);

	obj->pages = NULL;

}