f2fs: use percpu_counter for # of dirty pages in inode

This patch adds percpu_counter for # of dirty pages in inode.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/f2fs.h

@@ -436,7 +436,7 @@ struct f2fs_inode_info {
 	/* Use below internally in f2fs*/
 	unsigned long flags;		/* use to pass per-file flags */
 	struct rw_semaphore i_sem;	/* protect fi info */
-	atomic_t dirty_pages;		/* # of dirty pages */
+	struct percpu_counter dirty_pages;	/* # of dirty pages */
 	f2fs_hash_t chash;		/* hash value of given file name */
 	unsigned int clevel;		/* maximum level of given file name */
 	nid_t i_xattr_nid;		/* node id that contains xattrs */
@@ -1166,7 +1166,7 @@ static inline void inc_page_count(struct f2fs_sb_info *sbi, int count_type)
 
 static inline void inode_inc_dirty_pages(struct inode *inode)
 {
-	atomic_inc(&F2FS_I(inode)->dirty_pages);
+	percpu_counter_inc(&F2FS_I(inode)->dirty_pages);
 	inc_page_count(F2FS_I_SB(inode), S_ISDIR(inode->i_mode) ?
 				F2FS_DIRTY_DENTS : F2FS_DIRTY_DATA);
 }
@@ -1182,7 +1182,7 @@ static inline void inode_dec_dirty_pages(struct inode *inode)
 			!S_ISLNK(inode->i_mode))
 		return;
 
-	atomic_dec(&F2FS_I(inode)->dirty_pages);
+	percpu_counter_dec(&F2FS_I(inode)->dirty_pages);
 	dec_page_count(F2FS_I_SB(inode), S_ISDIR(inode->i_mode) ?
 				F2FS_DIRTY_DENTS : F2FS_DIRTY_DATA);
 }
@@ -1192,9 +1192,9 @@ static inline s64 get_pages(struct f2fs_sb_info *sbi, int count_type)
 	return percpu_counter_sum_positive(&sbi->nr_pages[count_type]);
 }
 
-static inline int get_dirty_pages(struct inode *inode)
+static inline s64 get_dirty_pages(struct inode *inode)
 {
-	return atomic_read(&F2FS_I(inode)->dirty_pages);
+	return percpu_counter_sum_positive(&F2FS_I(inode)->dirty_pages);
 }
 
 static inline int get_blocktype_secs(struct f2fs_sb_info *sbi, int block_type)

fs/f2fs/file.c

@@ -1419,7 +1419,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
 		goto out;
 
 	f2fs_msg(F2FS_I_SB(inode)->sb, KERN_WARNING,
-		"Unexpected flush for atomic writes: ino=%lu, npages=%u",
+		"Unexpected flush for atomic writes: ino=%lu, npages=%lld",
 					inode->i_ino, get_dirty_pages(inode));
 	ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX);
 	if (ret)

fs/f2fs/super.c

@@ -526,9 +526,13 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
 
 	init_once((void *) fi);
 
+	if (percpu_counter_init(&fi->dirty_pages, 0, GFP_NOFS)) {
+		kmem_cache_free(f2fs_inode_cachep, fi);
+		return NULL;
+	}
+
 	/* Initialize f2fs-specific inode info */
 	fi->vfs_inode.i_version = 1;
-	atomic_set(&fi->dirty_pages, 0);
 	fi->i_current_depth = 1;
 	fi->i_advise = 0;
 	init_rwsem(&fi->i_sem);
@@ -603,6 +607,7 @@ static void f2fs_i_callback(struct rcu_head *head)
 
 static void f2fs_destroy_inode(struct inode *inode)
 {
+	percpu_counter_destroy(&F2FS_I(inode)->dirty_pages);
 	call_rcu(&inode->i_rcu, f2fs_i_callback);
 }