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From: Christoph Hellwig <hch@lst.de>
To: linux-mm@kvack.org
Cc: Matthew Wilcox <willy@infradead.org>,
	Jan Kara <jack@suse.com>,
	David Howells <dhowells@redhat.com>,
	Brian Foster <bfoster@redhat.com>,
	Christian Brauner <brauner@kernel.org>,
	"Darrick J. Wong" <djwong@kernel.org>,
	linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Jan Kara <jack@suse.cz>,
	Dave Chinner <dchinner@redhat.com>
Subject: [PATCH 11/13] writeback: Move the folio_prepare_writeback loop out of write_cache_pages()
Date: Sat,  3 Feb 2024 08:11:45 +0100
Message-Id: <20240203071147.862076-12-hch@lst.de>
In-Reply-To: <20240203071147.862076-1-hch@lst.de>
References: <20240203071147.862076-1-hch@lst.de>
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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: Brian Foster <bfoster@redhat.com>
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 095ba4db9dcc17..3abb053e70580e 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2411,6 +2411,7 @@ 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);
@@ -2418,8 +2419,17 @@ 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;
 }
 
@@ -2480,14 +2490,6 @@ int write_cache_pages(struct address_space *mapping,
 		if (!folio)
 			break;
 
-		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);
 		wbc->nr_to_write -= folio_nr_pages(folio);
 
-- 
2.39.2