f2fs: add write latency stats for NAT and SIT blocks in f2fs_write_checkpoint

This patch adds separate write latency accounting for NAT and SIT blocks
in f2fs_write_checkpoint().

Signed-off-by: Yongpeng Yang <yangyongpeng@xiaomi.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Author: Yongpeng Yang

fs/f2fs/checkpoint.c

@@ -1839,6 +1839,7 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 			goto out;
 		}
 	}
+	stat_cp_time(cpc, CP_TIME_MERGE_WRITE);
 
 	/*
 	 * update checkpoint pack index
@@ -1855,10 +1856,11 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
 		f2fs_bug_on(sbi, !f2fs_cp_error(sbi));
 		goto stop;
 	}
+	stat_cp_time(cpc, CP_TIME_FLUSH_NAT);
 
 	f2fs_flush_sit_entries(sbi, cpc);
 
-	stat_cp_time(cpc, CP_TIME_FLUSH_META);
+	stat_cp_time(cpc, CP_TIME_FLUSH_SIT);
 
 	/* save inmem log status */
 	f2fs_save_inmem_curseg(sbi);

fs/f2fs/f2fs.h

@@ -319,7 +319,9 @@ enum cp_time {
 	CP_TIME_START,		/* begin */
 	CP_TIME_LOCK,		/* after cp_global_sem */
 	CP_TIME_OP_LOCK,	/* after block_operation */
-	CP_TIME_FLUSH_META,	/* after flush sit/nat */
+	CP_TIME_MERGE_WRITE,	/* after flush DATA/NODE/META */
+	CP_TIME_FLUSH_NAT,	/* after flush nat */
+	CP_TIME_FLUSH_SIT,	/* after flush sit */
 	CP_TIME_SYNC_META,	/* after sync_meta_pages */
 	CP_TIME_SYNC_CP_META,	/* after sync cp meta pages */
 	CP_TIME_WAIT_DIRTY_META,/* after wait on dirty meta */