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Commit a6906972 authored by Matthew Wilcox's avatar Matthew Wilcox
Browse files

page cache; Convert find_get_pages_range_tag 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 3ece58a2

include/linux/pagemap.h

+2 −2
Original line number Diff line number Diff line
@@ -363,10 +363,10 @@ static inline unsigned find_get_pages(struct address_space *mapping, 
unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,

			       unsigned int nr_pages, struct page **pages);

unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,

			pgoff_t end, int tag, unsigned int nr_pages,

			pgoff_t end, xa_mark_t tag, unsigned int nr_pages,

			struct page **pages);

static inline unsigned find_get_pages_tag(struct address_space *mapping,

			pgoff_t *index, int tag, unsigned int nr_pages,

			pgoff_t *index, xa_mark_t tag, unsigned int nr_pages,

			struct page **pages)

{

	return find_get_pages_range_tag(mapping, index, (pgoff_t)-1, tag,

mm/filemap.c

+26 −42
Original line number Diff line number Diff line
@@ -1789,74 +1789,58 @@ EXPORT_SYMBOL(find_get_pages_contig); 
 * @tag.   We update @index to index the next page for the traversal.

 */

unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,

			pgoff_t end, int tag, unsigned int nr_pages,

			pgoff_t end, xa_mark_t tag, unsigned int nr_pages,

			struct page **pages)

{

	struct radix_tree_iter iter;

	void **slot;

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

	struct page *page;

	unsigned ret = 0;



	if (unlikely(!nr_pages))

		return 0;



	rcu_read_lock();

	radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, *index, tag) {

		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_marked(&xas, page, end, tag) {

		struct page *head;

		if (xas_retry(&xas, page))

			continue;

			}

		/*

			 * A shadow entry of a recently evicted page.

			 *

			 * Those entries should never be tagged, but

			 * this tree walk is lockless and the tags are

			 * looked up in bulk, one radix tree node at a

			 * time, so there is a sizable window for page

			 * reclaim to evict a page we saw tagged.

			 *

			 * Skip over it.

		 * Shadow entries should never be tagged, but this iteration

		 * is lockless so there is a window for page reclaim to evict

		 * a page we saw tagged.  Skip over it.

		 */

		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) {

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

			*index = page->index + 1;

			goto out;

		}

		continue;

put_page:

		put_page(head);

retry:

		xas_reset(&xas);

	}



	/*

	 * We come here when we got at @end. We take care to not overflow the

	 * We come here when we got to @end. We take care to not overflow the

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

	 * iteration when there is page at index -1 but that is already broken

	 * anyway.

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

	 * broken anyway.

	 */

	if (end == (pgoff_t)-1)

		*index = (pgoff_t)-1;