linux-kernel - [PATCH 1/3] f2fs: skip writing in ->writepages when no dirty pages exist

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Date:	Fri, 17 Jul 2015 18:02:39 +0800
From:	Chao Yu <chao2.yu@...sung.com>
To:	Jaegeuk Kim <jaegeuk@...nel.org>
Cc:	linux-f2fs-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] f2fs: skip writing in ->writepages when no dirty pages
 exist

When flushing comes from background, if there is no dirty page in the
mapping of inode, we'd better to skip seeking dirty page from mapping
for writebacking.

Signed-off-by: Chao Yu <chao2.yu@...sung.com>
---
 fs/f2fs/data.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index b621c08..5370a74 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1284,6 +1284,10 @@ static int f2fs_write_data_pages(struct address_space *mapping,
 	if (!mapping->a_ops->writepage)
 		return 0;
 
+	/* skip writing if there is no dirty page in this inode */
+	if (!get_dirty_pages(inode) && wbc->sync_mode == WB_SYNC_NONE)
+		return 0;
+
 	if (S_ISDIR(inode->i_mode) && wbc->sync_mode == WB_SYNC_NONE &&
 			get_dirty_pages(inode) < nr_pages_to_skip(sbi, DATA) &&
 			available_free_memory(sbi, DIRTY_DENTS))
-- 
2.4.2


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