[PATCH v2 1/2] writeback: Export folio_prepare_writeback()

[Jan Kara <jack@suse.cz>]

The sequence of operations done in folio_prepare_writeback() is needed
practically by every writeback method. UDF is unable to easily use
writeback_iter() for inodes with inline format (due to complexities with
racing conversion and fallback) so export folio_prepare_writeback() for
it instead of opencoding it in UDF. Later we can use this helper from
other filesystems as well.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 include/linux/writeback.h | 2 ++
 mm/page-writeback.c       | 4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index e530112c4b3a..3e5d215c8d27 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -357,6 +357,8 @@ bool wb_over_bg_thresh(struct bdi_writeback *wb);
 
 struct folio *writeback_iter(struct address_space *mapping,
 		struct writeback_control *wbc, struct folio *folio, int *error);
+bool folio_prepare_writeback(struct address_space *mapping,
+		struct writeback_control *wbc, struct folio *folio);
 
 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 void writeback_set_ratelimit(void);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 601a5e048d12..ceb78798fc00 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2358,7 +2358,7 @@ void tag_pages_for_writeback(struct address_space *mapping,
 }
 EXPORT_SYMBOL(tag_pages_for_writeback);
 
-static bool folio_prepare_writeback(struct address_space *mapping,
+bool folio_prepare_writeback(struct address_space *mapping,
 		struct writeback_control *wbc, struct folio *folio)
 {
 	/*
@@ -2389,7 +2389,7 @@ static bool folio_prepare_writeback(struct address_space *mapping,
 
 	return true;
 }
-
+EXPORT_SYMBOL_GPL(folio_prepare_writeback);
 
 static pgoff_t wbc_end(struct writeback_control *wbc)
 {
-- 
2.51.0