f2fs: avoid lock debugging overhead

If CONFIG_F2FS_CHECK_FS is unset, we don't need to add any debugging overhead.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

fs/f2fs/f2fs.h

@@ -22,8 +22,10 @@
 
 #ifdef CONFIG_F2FS_CHECK_FS
 #define f2fs_bug_on(condition)	BUG_ON(condition)
+#define f2fs_down_write(x, y)	down_write_nest_lock(x, y)
 #else
 #define f2fs_bug_on(condition)
+#define f2fs_down_write(x, y)	down_write(x)
 #endif
 
 /*
@@ -556,7 +558,7 @@ static inline void f2fs_unlock_op(struct f2fs_sb_info *sbi)
 
 static inline void f2fs_lock_all(struct f2fs_sb_info *sbi)
 {
-	down_write_nest_lock(&sbi->cp_rwsem, &sbi->cp_mutex);
+	f2fs_down_write(&sbi->cp_rwsem, &sbi->cp_mutex);
 }
 
 static inline void f2fs_unlock_all(struct f2fs_sb_info *sbi)