[PATCH v1 1/2] mm/filemap: Do not use is_partially_uptodate for entire folio

[Chi Zhiling]

From: Chi Zhiling <chizhiling@xxxxxxxxxx>

When a folio is marked as non-uptodate, it means the folio contains
some non-uptodate data. Therefore, calling is_partially_uptodate()
to recheck the entire folio is redundant.

If all data in a folio is actually up-to-date but the folio lacks the
uptodate flag, it will still be treated as non-uptodate in many other
places. Thus, there should be no special case handling for filemap.

Signed-off-by: Chi Zhiling <chizhiling@xxxxxxxxxx>
---
 mm/filemap.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/filemap.c b/mm/filemap.c
index 0e103fc99a8e..00c30f7f7dc3 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2447,6 +2447,9 @@ static bool filemap_range_uptodate(struct address_space *mapping,
 		pos -= folio_pos(folio);
 	}
 
+	if (pos == 0 && count >= folio_size(folio))
+		return false;
+
 	return mapping->a_ops->is_partially_uptodate(folio, pos, count);
 }
 
-- 
2.43.0