f2fs: improve definition of statistic macros

With a recent addition of f2fs_lookup_extent_tree(), we get a warning about
the use of empty macros:

fs/f2fs/extent_cache.c: In function 'f2fs_lookup_extent_tree':
fs/f2fs/extent_cache.c:358:32: error: suggest braces around empty body in an 'else' statement [-Werror=empty-body]
   stat_inc_rbtree_node_hit(sbi);

A good way to avoid the warning and make the code more robust is to define
all no-op macros as 'do { } while (0)'.

Fixes: 54c2258 ("f2fs: extract rb-tree operation infrastructure")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reivewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -2532,35 +2532,35 @@ void f2fs_destroy_stats(struct f2fs_sb_info *sbi);
 int __init f2fs_create_root_stats(void);
 void f2fs_destroy_root_stats(void);
 #else
-#define stat_inc_cp_count(si)
-#define stat_inc_bg_cp_count(si)
-#define stat_inc_call_count(si)
-#define stat_inc_bggc_count(si)
-#define stat_inc_dirty_inode(sbi, type)
-#define stat_dec_dirty_inode(sbi, type)
-#define stat_inc_total_hit(sb)
-#define stat_inc_rbtree_node_hit(sb)
-#define stat_inc_largest_node_hit(sbi)
-#define stat_inc_cached_node_hit(sbi)
-#define stat_inc_inline_xattr(inode)
-#define stat_dec_inline_xattr(inode)
-#define stat_inc_inline_inode(inode)
-#define stat_dec_inline_inode(inode)
-#define stat_inc_inline_dir(inode)
-#define stat_dec_inline_dir(inode)
-#define stat_inc_atomic_write(inode)
-#define stat_dec_atomic_write(inode)
-#define stat_update_max_atomic_write(inode)
-#define stat_inc_volatile_write(inode)
-#define stat_dec_volatile_write(inode)
-#define stat_update_max_volatile_write(inode)
-#define stat_inc_seg_type(sbi, curseg)
-#define stat_inc_block_count(sbi, curseg)
-#define stat_inc_inplace_blocks(sbi)
-#define stat_inc_seg_count(sbi, type, gc_type)
-#define stat_inc_tot_blk_count(si, blks)
-#define stat_inc_data_blk_count(sbi, blks, gc_type)
-#define stat_inc_node_blk_count(sbi, blks, gc_type)
+#define stat_inc_cp_count(si)				do { } while (0)
+#define stat_inc_bg_cp_count(si)			do { } while (0)
+#define stat_inc_call_count(si)				do { } while (0)
+#define stat_inc_bggc_count(si)				do { } while (0)
+#define stat_inc_dirty_inode(sbi, type)			do { } while (0)
+#define stat_dec_dirty_inode(sbi, type)			do { } while (0)
+#define stat_inc_total_hit(sb)				do { } while (0)
+#define stat_inc_rbtree_node_hit(sb)			do { } while (0)
+#define stat_inc_largest_node_hit(sbi)			do { } while (0)
+#define stat_inc_cached_node_hit(sbi)			do { } while (0)
+#define stat_inc_inline_xattr(inode)			do { } while (0)
+#define stat_dec_inline_xattr(inode)			do { } while (0)
+#define stat_inc_inline_inode(inode)			do { } while (0)
+#define stat_dec_inline_inode(inode)			do { } while (0)
+#define stat_inc_inline_dir(inode)			do { } while (0)
+#define stat_dec_inline_dir(inode)			do { } while (0)
+#define stat_inc_atomic_write(inode)			do { } while (0)
+#define stat_dec_atomic_write(inode)			do { } while (0)
+#define stat_update_max_atomic_write(inode)		do { } while (0)
+#define stat_inc_volatile_write(inode)			do { } while (0)
+#define stat_dec_volatile_write(inode)			do { } while (0)
+#define stat_update_max_volatile_write(inode)		do { } while (0)
+#define stat_inc_seg_type(sbi, curseg)			do { } while (0)
+#define stat_inc_block_count(sbi, curseg)		do { } while (0)
+#define stat_inc_inplace_blocks(sbi)			do { } while (0)
+#define stat_inc_seg_count(sbi, type, gc_type)		do { } while (0)
+#define stat_inc_tot_blk_count(si, blks)		do { } while (0)
+#define stat_inc_data_blk_count(sbi, blks, gc_type)	do { } while (0)
+#define stat_inc_node_blk_count(sbi, blks, gc_type)	do { } while (0)
 
 static inline int f2fs_build_stats(struct f2fs_sb_info *sbi) { return 0; }
 static inline void f2fs_destroy_stats(struct f2fs_sb_info *sbi) { }