Unverified Commit a1d98e4f authored by Jens Axboe's avatar Jens Axboe Committed by Christian Brauner
Browse files

mm/filemap: unify dropbehind flag testing and clearing 



The read and write side does this a bit differently, unify it such that
the _{read,write} helpers check the bit before locking, and the generic
handler is in charge of clearing the bit and invalidating, once under
the folio lock.

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/20250527133255.452431-6-axboe@kernel.dk


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 1da7a06d

mm/filemap.c

+11 −10
Original line number Diff line number Diff line
@@ -1595,7 +1595,11 @@ static void filemap_end_dropbehind(struct folio *folio) 


	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);



	if (mapping && !folio_test_writeback(folio) && !folio_test_dirty(folio))

	if (folio_test_writeback(folio) || folio_test_dirty(folio))

		return;

	if (!folio_test_clear_dropbehind(folio))

		return;

	if (mapping)

		folio_unmap_invalidate(mapping, folio, 0);

}
@@ -1606,6 +1610,9 @@ static void filemap_end_dropbehind(struct folio *folio) 
 */

static void filemap_end_dropbehind_write(struct folio *folio)

{

	if (!folio_test_dropbehind(folio))

		return;



	/*

	 * Hitting !in_task() should not happen off RWF_DONTCACHE writeback,

	 * but can happen if normal writeback just happens to find dirty folios
@@ -1629,8 +1636,6 @@ static void filemap_end_dropbehind_write(struct folio *folio) 
 */

void folio_end_writeback(struct folio *folio)

{

	bool folio_dropbehind = false;



	VM_BUG_ON_FOLIO(!folio_test_writeback(folio), folio);



	/*
@@ -1652,14 +1657,11 @@ void folio_end_writeback(struct folio *folio) 
	 * reused before the folio_wake_bit().

	 */

	folio_get(folio);

	if (!folio_test_dirty(folio))

		folio_dropbehind = folio_test_clear_dropbehind(folio);

	if (__folio_end_writeback(folio))

		folio_wake_bit(folio, PG_writeback);

	acct_reclaim_writeback(folio);



	if (folio_dropbehind)

	filemap_end_dropbehind_write(folio);

	acct_reclaim_writeback(folio);

	folio_put(folio);

}

EXPORT_SYMBOL(folio_end_writeback);
@@ -2651,7 +2653,6 @@ static void filemap_end_dropbehind_read(struct folio *folio) 
	if (folio_test_writeback(folio) || folio_test_dirty(folio))

		return;

	if (folio_trylock(folio)) {

		if (folio_test_clear_dropbehind(folio))

		filemap_end_dropbehind(folio);

		folio_unlock(folio);

	}