Commit fd1b3cee authored by Matthew Wilcox's avatar Matthew Wilcox
Browse files

page cache: Convert find_get_pages_range to XArray 



The 'end' parameter of the xas_for_each iterator avoids a useless
iteration at the end of the range.

Signed-off-by: default avatarMatthew Wilcox <willy@infradead.org>
parent f280bf09

mm/filemap.c

+19 −33
Original line number Diff line number Diff line
@@ -1650,64 +1650,50 @@ unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start, 
			      pgoff_t end, unsigned int nr_pages,

			      struct page **pages)

{

	struct radix_tree_iter iter;

	void **slot;

	XA_STATE(xas, &mapping->i_pages, *start);

	struct page *page;

	unsigned ret = 0;



	if (unlikely(!nr_pages))

		return 0;



	rcu_read_lock();

	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, *start) {

		struct page *head, *page;



		if (iter.index > end)

			break;

repeat:

		page = radix_tree_deref_slot(slot);

		if (unlikely(!page))

			continue;



		if (radix_tree_exception(page)) {

			if (radix_tree_deref_retry(page)) {

				slot = radix_tree_iter_retry(&iter);

	xas_for_each(&xas, page, end) {

		struct page *head;

		if (xas_retry(&xas, page))

			continue;

			}

			/*

			 * A shadow entry of a recently evicted page,

			 * or a swap entry from shmem/tmpfs.  Skip

			 * over it.

			 */

		/* Skip over shadow, swap and DAX entries */

		if (xa_is_value(page))

			continue;

		}



		head = compound_head(page);

		if (!page_cache_get_speculative(head))

			goto repeat;

			goto retry;



		/* The page was split under us? */

		if (compound_head(page) != head) {

			put_page(head);

			goto repeat;

		}

		if (compound_head(page) != head)

			goto put_page;



		/* Has the page moved? */

		if (unlikely(page != *slot)) {

			put_page(head);

			goto repeat;

		}

		if (unlikely(page != xas_reload(&xas)))

			goto put_page;



		pages[ret] = page;

		if (++ret == nr_pages) {

			*start = pages[ret - 1]->index + 1;

			*start = page->index + 1;

			goto out;

		}

		continue;

put_page:

		put_page(head);

retry:

		xas_reset(&xas);

	}



	/*

	 * We come here when there is no page beyond @end. We take care to not

	 * overflow the index @start as it confuses some of the callers. This

	 * breaks the iteration when there is page at index -1 but that is

	 * breaks the iteration when there is a page at index -1 but that is

	 * already broken anyway.

	 */

	if (end == (pgoff_t)-1)