f2fs: use atomic_t to record hit ratio info of extent cache

Variables for recording extent cache ratio info were updated without
protection, this patch tries to alter them to atomic_t type for more
accurate stat.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/debug.c

@@ -33,8 +33,8 @@ static void update_general_status(struct f2fs_sb_info *sbi)
 	int i;
 
 	/* validation check of the segment numbers */
-	si->hit_ext = sbi->read_hit_ext;
-	si->total_ext = sbi->total_hit_ext;
+	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;
 	si->ext_node = atomic_read(&sbi->total_ext_node);
 	si->ndirty_node = get_pages(sbi, F2FS_DIRTY_NODES);
@@ -369,6 +369,9 @@ int f2fs_build_stats(struct f2fs_sb_info *sbi)
 	si->sbi = sbi;
 	sbi->stat_info = si;
 
+	atomic_set(&sbi->total_hit_ext, 0);
+	atomic_set(&sbi->read_hit_ext, 0);
+
 	atomic_set(&sbi->inline_xattr, 0);
 	atomic_set(&sbi->inline_inode, 0);
 	atomic_set(&sbi->inline_dir, 0);

fs/f2fs/extent_cache.c

@@ -279,7 +279,7 @@ static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
 			et->largest.fofs + et->largest.len > pgofs) {
 		*ei = et->largest;
 		ret = true;
-		stat_inc_read_hit(sbi->sb);
+		stat_inc_read_hit(sbi);
 		goto out;
 	}
 
@@ -292,10 +292,10 @@ static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
 		et->cached_en = en;
 		spin_unlock(&sbi->extent_lock);
 		ret = true;
-		stat_inc_read_hit(sbi->sb);
+		stat_inc_read_hit(sbi);
 	}
 out:
-	stat_inc_total_hit(sbi->sb);
+	stat_inc_total_hit(sbi);
 	read_unlock(&et->lock);
 
 	trace_f2fs_lookup_extent_tree_end(inode, pgofs, ei);

fs/f2fs/f2fs.h

@@ -781,7 +781,8 @@ struct f2fs_sb_info {
 	unsigned int segment_count[2];		/* # of allocated segments */
 	unsigned int block_count[2];		/* # of allocated blocks */
 	atomic_t inplace_count;		/* # of inplace update */
-	int total_hit_ext, read_hit_ext;	/* extent cache hit ratio */
+	atomic_t total_hit_ext;			/* # of lookup extent cache */
+	atomic_t read_hit_ext;			/* # of hit extent cache */
 	atomic_t inline_xattr;			/* # of inline_xattr inodes */
 	atomic_t inline_inode;			/* # of inline_data inodes */
 	atomic_t inline_dir;			/* # of inline_dentry inodes */
@@ -1837,8 +1838,8 @@ static inline struct f2fs_stat_info *F2FS_STAT(struct f2fs_sb_info *sbi)
 #define stat_inc_bggc_count(sbi)	((sbi)->bg_gc++)
 #define stat_inc_dirty_dir(sbi)		((sbi)->n_dirty_dirs++)
 #define stat_dec_dirty_dir(sbi)		((sbi)->n_dirty_dirs--)
-#define stat_inc_total_hit(sb)		((F2FS_SB(sb))->total_hit_ext++)
-#define stat_inc_read_hit(sb)		((F2FS_SB(sb))->read_hit_ext++)
+#define stat_inc_total_hit(sbi)		(atomic_inc(&(sbi)->total_hit_ext))
+#define stat_inc_read_hit(sbi)		(atomic_inc(&(sbi)->read_hit_ext))
 #define stat_inc_inline_xattr(inode)					\
 	do {								\
 		if (f2fs_has_inline_xattr(inode))			\