[RFC PATCH v1 07/10] mm: add no_stats_accounting bitfield to wbc

[Joanne Koong <joannelkoong@gmail.com>]

Add a no_stats_accounting bitfield to wbc that callers can set. Hook
this up to __folio_clear_dirty_for_io() when preparing writeback.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
---
 include/linux/writeback.h | 3 +++
 mm/page-writeback.c       | 3 ++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 34afa6912a1c..000795a47cb3 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -72,6 +72,9 @@ struct writeback_control {
 	 */
 	unsigned no_cgroup_owner:1;
 
+	/* Do not do any stats accounting. The caller will do this themselves */
+	unsigned no_stats_accounting:1;
+
 	/* To enable batching of swap writes to non-block-device backends,
 	 * "plug" can be set point to a 'struct swap_iocb *'.  When all swap
 	 * writes have been submitted, if with swap_iocb is not NULL,
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 77a46bf8052f..c1fec76ee869 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2404,6 +2404,7 @@ void tag_pages_for_writeback(struct address_space *mapping,
 }
 EXPORT_SYMBOL(tag_pages_for_writeback);
 
+static bool __folio_clear_dirty_for_io(struct folio *folio, bool update_stats);
 static bool folio_prepare_writeback(struct address_space *mapping,
 		struct writeback_control *wbc, struct folio *folio)
 {
@@ -2430,7 +2431,7 @@ static bool folio_prepare_writeback(struct address_space *mapping,
 	}
 	BUG_ON(folio_test_writeback(folio));
 
-	if (!folio_clear_dirty_for_io(folio))
+	if (!__folio_clear_dirty_for_io(folio, !wbc->no_stats_accounting))
 		return false;
 
 	return true;
-- 
2.47.3