[PATCH 4/6] filemap: Convert __readahead_batch() to use a folio

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

Extract folios from i_mapping, not pages.  Removes a hidden call to
compound_head(), a use of thp_nr_pages() and an unnecessary assertion
that we didn't find a tail page in the page cache.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/pagemap.h | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index e51c0febd036..f4b875b561e5 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -1449,7 +1449,7 @@ static inline unsigned int __readahead_batch(struct readahead_control *rac,
 {
 	unsigned int i = 0;
 	XA_STATE(xas, &rac->mapping->i_pages, 0);
-	struct page *page;
+	struct folio *folio;
 
 	BUG_ON(rac->_batch_count > rac->_nr_pages);
 	rac->_nr_pages -= rac->_batch_count;
@@ -1458,13 +1458,12 @@ static inline unsigned int __readahead_batch(struct readahead_control *rac,
 
 	xas_set(&xas, rac->_index);
 	rcu_read_lock();
-	xas_for_each(&xas, page, rac->_index + rac->_nr_pages - 1) {
-		if (xas_retry(&xas, page))
+	xas_for_each(&xas, folio, rac->_index + rac->_nr_pages - 1) {
+		if (xas_retry(&xas, folio))
 			continue;
-		VM_BUG_ON_PAGE(!PageLocked(page), page);
-		VM_BUG_ON_PAGE(PageTail(page), page);
-		array[i++] = page;
-		rac->_batch_count += thp_nr_pages(page);
+		VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
+		array[i++] = folio_page(folio, 0);
+		rac->_batch_count += folio_nr_pages(folio);
 		if (i == array_sz)
 			break;
 	}
-- 
2.47.2