[PATCH] mm: skip dirty file folios during isolation

["zhaoyang.huang" <zhaoyang.huang@unisoc.com>]

From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>

Since dirty file folios are no longer writeout in reclaiming after
'commit 84798514db50 ("mm: Remove swap_writepage() and
shmem_writepage()")', there is no need to isolate them from LRU which
could help to improve the scan efficiency.

Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
---
 mm/vmscan.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 10f1e7d716ca..3a029dede5ce 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4507,6 +4507,7 @@ static bool sort_folio(struct lruvec *lruvec, struct folio *folio, struct scan_c
 static bool isolate_folio(struct lruvec *lruvec, struct folio *folio, struct scan_control *sc)
 {
 	bool success;
+	struct address_space *mapping = folio_mapping(folio);
 
 	/* swap constrained */
 	if (!(sc->gfp_mask & __GFP_IO) &&
@@ -4514,6 +4515,11 @@ static bool isolate_folio(struct lruvec *lruvec, struct folio *folio, struct sca
 	     (folio_test_anon(folio) && !folio_test_swapcache(folio))))
 		return false;
 
+	/* skip dirty file pages since they can't be writeout */
+	if (mapping && !shmem_mapping(mapping) &&
+		!folio_test_anon(folio) && folio_test_dirty(folio))
+		return false;
+
 	/* raced with release_pages() */
 	if (!folio_try_get(folio))
 		return false;
-- 
2.25.1