f2fs: add largest/cached stat in extent cache

This patch adds to stat the hit count of largest/cached node for showing
in debugfs.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
index bc215fd..1a1a4c6 100644
--- a/fs/f2fs/debug.c
+++ b/fs/f2fs/debug.c
@@ -33,6 +33,8 @@
 	int i;
 
 	/* validation check of the segment numbers */
+	si->hit_largest = atomic_read(&sbi->read_hit_largest);
+	si->hit_cached = atomic_read(&sbi->read_hit_cached);
 	si->hit_ext = atomic_read(&sbi->read_hit_ext);
 	si->total_ext = atomic_read(&sbi->total_hit_ext);
 	si->ext_tree = sbi->total_ext_tree;
@@ -279,8 +281,9 @@
 				si->bg_data_blks);
 		seq_printf(s, "  - node blocks : %d (%d)\n", si->node_blks,
 				si->bg_node_blks);
-		seq_printf(s, "\nExtent Hit Ratio: %d / %d\n",
-			   si->hit_ext, si->total_ext);
+		seq_printf(s, "\nExtent Hit Ratio: L1-1:%d L1-2:%d L2:%d / %d\n",
+				si->hit_largest, si->hit_cached,
+				si->hit_ext, si->total_ext);
 		seq_printf(s, "\nExtent Tree Count: %d\n", si->ext_tree);
 		seq_printf(s, "\nExtent Node Count: %d\n", si->ext_node);
 		seq_puts(s, "\nBalancing F2FS Async:\n");
@@ -371,6 +374,8 @@
 
 	atomic_set(&sbi->total_hit_ext, 0);
 	atomic_set(&sbi->read_hit_ext, 0);
+	atomic_set(&sbi->read_hit_largest, 0);
+	atomic_set(&sbi->read_hit_cached, 0);
 
 	atomic_set(&sbi->inline_xattr, 0);
 	atomic_set(&sbi->inline_inode, 0);