[PATCH 13/19] writeback: Move the folio_prepare_writeback loop out of write_cache_pages()

Christoph Hellwig
2024-01-25T08:58:56Z

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

Move the loop for should-we-write-this-folio to writeback_get_folio.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
[hch: folded the loop into the existing helper instead of a separate one
as suggested by Jan Kara]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Dave Chinner <dchinner@redhat.com>
---
mm/page-writeback.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index ae9f659e6796ac..d170dab07402ce 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2434,6 +2434,7 @@ static struct folio *writeback_get_folio(struct address_space *mapping,
{
struct folio *folio;

+retry:
folio = folio_batch_next(&wbc->fbatch);
if (!folio) {
folio_batch_release(&wbc->fbatch);
@@ -2441,8 +2442,17 @@ static struct folio *writeback_get_folio(struct address_space *mapping,
filemap_get_folios_tag(mapping, &wbc->index, wbc_end(wbc),
wbc_to_tag(wbc), &wbc->fbatch);
folio = folio_batch_next(&wbc->fbatch);
+ if (!folio)
+ return NULL;
}

+ folio_lock(folio);
+ if (unlikely(!folio_prepare_writeback(mapping, wbc, folio))) {
+ folio_unlock(folio);
+ goto retry;
+ }
+
+ trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
return folio;
}

@@ -2505,14 +2515,6 @@ int write_cache_pages(struct address_space *mapping,
folio = writeback_get_folio(mapping, wbc)) {
unsigned long nr;

- folio_lock(folio);
- if (!folio_prepare_writeback(mapping, wbc, folio)) {
- folio_unlock(folio);
- continue;
- }
-
- trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
-
error = writepage(folio, wbc, data);
nr = folio_nr_pages(folio);
wbc->nr_to_write -= nr;
--
2.39.2