---

yaml
---
r: 348979
b: refs/heads/master
c: a7fdffb
h: refs/heads/master
i:
  348977: acde059
  348975: a11519d
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: c01e54b770e69c65525295eb2668be3dc0822406
+refs/heads/master: a7fdffbd3ea4b3cc2993af006bde38a423b38b72

trunk/fs/f2fs/node.c

@@ -1124,24 +1124,29 @@ static int f2fs_write_node_page(struct page *page,
 	return 0;
 }
 
+/*
+ * It is very important to gather dirty pages and write at once, so that we can
+ * submit a big bio without interfering other data writes.
+ * Be default, 512 pages (2MB), a segment size, is quite reasonable.
+ */
+#define COLLECT_DIRTY_NODES	512
 static int f2fs_write_node_pages(struct address_space *mapping,
 			    struct writeback_control *wbc)
 {
 	struct f2fs_sb_info *sbi = F2FS_SB(mapping->host->i_sb);
 	struct block_device *bdev = sbi->sb->s_bdev;
 	long nr_to_write = wbc->nr_to_write;
 
-	if (wbc->for_kupdate)
-		return 0;
-
-	if (get_pages(sbi, F2FS_DIRTY_NODES) == 0)
-		return 0;
-
+	/* First check balancing cached NAT entries */
 	if (try_to_free_nats(sbi, NAT_ENTRY_PER_BLOCK)) {
 		write_checkpoint(sbi, false, false);
 		return 0;
 	}
 
+	/* collect a number of dirty node pages and write together */
+	if (get_pages(sbi, F2FS_DIRTY_NODES) < COLLECT_DIRTY_NODES)
+		return 0;
+
 	/* if mounting is failed, skip writing node pages */
 	wbc->nr_to_write = bio_get_nr_vecs(bdev);
 	sync_node_pages(sbi, 0, wbc);