+static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa,
+ pgoff_t index, unsigned int nr_pages)
+{
+ XA_STATE(xas, xa, index);
+ struct page *page;
+ unsigned int ret = 0;
+
+ rcu_read_lock();
+ for (page = xas_load(&xas); page; page = xas_next(&xas)) {
+ if (xas_retry(&xas, page))
+ continue;
+
+ /* Has the page moved or been split? */
+ if (unlikely(page != xas_reload(&xas))) {
+ xas_reset(&xas);
+ continue;
+ }
+
+ pages[ret] = find_subpage(page, xas.xa_index);
+ get_page(pages[ret]);
+ if (++ret == nr_pages)
+ break;
+ }
+ rcu_read_unlock();
+ return ret;
+}
+
+static ssize_t iter_xarray_get_pages(struct iov_iter *i,
+ struct page **pages, size_t maxsize,
+ unsigned maxpages, size_t *_start_offset)
+{
+ unsigned nr, offset;
+ pgoff_t index, count;
+ size_t size = maxsize, actual;
+ loff_t pos;
+
+ if (!size || !maxpages)
+ return 0;
+
+ pos = i->xarray_start + i->iov_offset;
+ index = pos >> PAGE_SHIFT;
+ offset = pos & ~PAGE_MASK;
+ *_start_offset = offset;
+
+ count = 1;
+ if (size > PAGE_SIZE - offset) {
+ size -= PAGE_SIZE - offset;
+ count += size >> PAGE_SHIFT;
+ size &= ~PAGE_MASK;
+ if (size)
+ count++;
+ }
+
+ if (count > maxpages)
+ count = maxpages;
+
+ nr = iter_xarray_populate_pages(pages, i->xarray, index, count);
+ if (nr == 0)
+ return 0;
+
+ actual = PAGE_SIZE * nr;
+ actual -= offset;
+ if (nr == count && size > 0) {
+ unsigned last_offset = (nr > 1) ? 0 : offset;
+ actual -= PAGE_SIZE - (last_offset + size);
+ }
+ return actual;
+}
+