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@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 801b0b0b08f4c0ee3461aabb656327e2b26ab0b6..e4081fc91012e53731d230f56c0364acf161a2c4 100644 (file)
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1275,6 +1275,10 @@ 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))