f2fs: use percpu_counter for total_valid_inode_count

This patch uses percpu_counter to avoid stat_lock.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -801,7 +801,6 @@ struct f2fs_sb_info {
 	unsigned int total_sections;		/* total section count */
 	unsigned int total_node_count;		/* total node block count */
 	unsigned int total_valid_node_count;	/* valid node block count */
-	unsigned int total_valid_inode_count;	/* valid inode count */
 	loff_t max_file_blocks;			/* max block index of file */
 	int active_logs;			/* # of active logs */
 	int dir_level;				/* directory level */
@@ -818,6 +817,9 @@ struct f2fs_sb_info {
 	/* # of allocated blocks */
 	struct percpu_counter alloc_valid_block_count;
 
+	/* valid inode count */
+	struct percpu_counter total_valid_inode_count;
+
 	struct f2fs_mount_info mount_opt;	/* mount options */
 
 	/* for cleaning operations */
@@ -1325,23 +1327,17 @@ static inline unsigned int valid_node_count(struct f2fs_sb_info *sbi)
 
 static inline void inc_valid_inode_count(struct f2fs_sb_info *sbi)
 {
-	spin_lock(&sbi->stat_lock);
-	f2fs_bug_on(sbi, sbi->total_valid_inode_count == sbi->total_node_count);
-	sbi->total_valid_inode_count++;
-	spin_unlock(&sbi->stat_lock);
+	percpu_counter_inc(&sbi->total_valid_inode_count);
 }
 
 static inline void dec_valid_inode_count(struct f2fs_sb_info *sbi)
 {
-	spin_lock(&sbi->stat_lock);
-	f2fs_bug_on(sbi, !sbi->total_valid_inode_count);
-	sbi->total_valid_inode_count--;
-	spin_unlock(&sbi->stat_lock);
+	percpu_counter_dec(&sbi->total_valid_inode_count);
 }
 
-static inline unsigned int valid_inode_count(struct f2fs_sb_info *sbi)
+static inline s64 valid_inode_count(struct f2fs_sb_info *sbi)
 {
-	return sbi->total_valid_inode_count;
+	return percpu_counter_sum_positive(&sbi->total_valid_inode_count);
 }
 
 static inline struct page *f2fs_grab_cache_page(struct address_space *mapping,

fs/f2fs/super.c

@@ -618,6 +618,7 @@ static void destroy_percpu_info(struct f2fs_sb_info *sbi)
 	for (i = 0; i < NR_COUNT_TYPE; i++)
 		percpu_counter_destroy(&sbi->nr_pages[i]);
 	percpu_counter_destroy(&sbi->alloc_valid_block_count);
+	percpu_counter_destroy(&sbi->total_valid_inode_count);
 }
 
 static void f2fs_put_super(struct super_block *sb)
@@ -1384,7 +1385,11 @@ static int init_percpu_info(struct f2fs_sb_info *sbi)
 			return err;
 	}
 
-	return percpu_counter_init(&sbi->alloc_valid_block_count, 0,
+	err = percpu_counter_init(&sbi->alloc_valid_block_count, 0, GFP_KERNEL);
+	if (err)
+		return err;
+
+	return percpu_counter_init(&sbi->total_valid_inode_count, 0,
 								GFP_KERNEL);
 }
 
@@ -1598,8 +1603,8 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 
 	sbi->total_valid_node_count =
 				le32_to_cpu(sbi->ckpt->valid_node_count);
-	sbi->total_valid_inode_count =
-				le32_to_cpu(sbi->ckpt->valid_inode_count);
+	percpu_counter_set(&sbi->total_valid_inode_count,
+				le32_to_cpu(sbi->ckpt->valid_inode_count));
 	sbi->user_block_count = le64_to_cpu(sbi->ckpt->user_block_count);
 	sbi->total_valid_block_count =
 				le64_to_cpu(sbi->ckpt->valid_block_count);