1 files changed, 19 insertions, 17 deletions

diff --git a/mm/readahead.c b/mm/readahead.c
index 20d36d6b055e..406756d34309 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -457,7 +457,7 @@ static inline int ra_alloc_folio(struct readahead_control *ractl, pgoff_t index,
 }
 
 void page_cache_ra_order(struct readahead_control *ractl,
-		struct file_ra_state *ra, unsigned int new_order)
+		struct file_ra_state *ra)
 {
 	struct address_space *mapping = ractl->mapping;
 	pgoff_t start = readahead_index(ractl);
@@ -468,24 +468,21 @@ void page_cache_ra_order(struct readahead_control *ractl,
 	unsigned int nofs;
 	int err = 0;
 	gfp_t gfp = readahead_gfp_mask(mapping);
-	unsigned int min_ra_size = max(4, mapping_min_folio_nrpages(mapping));
+	unsigned int new_order = ra->order;
 
-	/*
-	 * Fallback when size < min_nrpages as each folio should be
-	 * at least min_nrpages anyway.
-	 */
-	if (!mapping_large_folio_support(mapping) || ra->size < min_ra_size)
+	if (!mapping_large_folio_support(mapping)) {
+		ra->order = 0;
 		goto fallback;
+	}
 
 	limit = min(limit, index + ra->size - 1);
 
-	if (new_order < mapping_max_folio_order(mapping))
-		new_order += 2;
-
 	new_order = min(mapping_max_folio_order(mapping), new_order);
 	new_order = min_t(unsigned int, new_order, ilog2(ra->size));
 	new_order = max(new_order, min_order);
 
+	ra->order = new_order;
+
 	/* See comment in page_cache_ra_unbounded() */
 	nofs = memalloc_nofs_save();
 	filemap_invalidate_lock_shared(mapping);
@@ -617,8 +614,9 @@ void page_cache_sync_ra(struct readahead_control *ractl,
 	ra->size = min(contig_count + req_count, max_pages);
 	ra->async_size = 1;
 readit:
+	ra->order = 0;
 	ractl->_index = ra->start;
-	page_cache_ra_order(ractl, ra, 0);
+	page_cache_ra_order(ractl, ra);
 }
 EXPORT_SYMBOL_GPL(page_cache_sync_ra);
 
@@ -628,8 +626,7 @@ void page_cache_async_ra(struct readahead_control *ractl,
 	unsigned long max_pages;
 	struct file_ra_state *ra = ractl->ra;
 	pgoff_t index = readahead_index(ractl);
-	pgoff_t expected, start;
-	unsigned int order = folio_order(folio);
+	pgoff_t expected, start, end, aligned_end, align;
 
 	/* no readahead */
 	if (!ra->ra_pages)
@@ -652,7 +649,7 @@ void page_cache_async_ra(struct readahead_control *ractl,
 	 * Ramp up sizes, and push forward the readahead window.
 	 */
 	expected = round_down(ra->start + ra->size - ra->async_size,
-			1UL << order);
+			folio_nr_pages(folio));
 	if (index == expected) {
 		ra->start += ra->size;
 		/*
@@ -660,7 +657,6 @@ void page_cache_async_ra(struct readahead_control *ractl,
 		 * the readahead window.
 		 */
 		ra->size = max(ra->size, get_next_ra_size(ra, max_pages));
-		ra->async_size = ra->size;
 		goto readit;
 	}
 
@@ -681,10 +677,16 @@ void page_cache_async_ra(struct readahead_control *ractl,
 	ra->size = start - index;	/* old async_size */
 	ra->size += req_count;
 	ra->size = get_next_ra_size(ra, max_pages);
-	ra->async_size = ra->size;
 readit:
+	ra->order += 2;
+	align = 1UL << min(ra->order, ffs(max_pages) - 1);
+	end = ra->start + ra->size;
+	aligned_end = round_down(end, align);
+	if (aligned_end > ra->start)
+		ra->size -= end - aligned_end;
+	ra->async_size = ra->size;
 	ractl->_index = ra->start;
-	page_cache_ra_order(ractl, ra, order);
+	page_cache_ra_order(ractl, ra);
 }
 EXPORT_SYMBOL_GPL(page_cache_async_ra);