f2fs: call f2fs_balance_fs for setattr

If inode becomes dirty, we need to check the # of dirty inodes whether or not
further checkpoint would be required.
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -694,7 +694,6 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr)
 			err = f2fs_truncate(inode);
 			if (err)
 				return err;
-			f2fs_balance_fs(F2FS_I_SB(inode), true);
 		} else {
 			/*
 			 * do not trim all blocks after i_size if target size is
@@ -723,6 +722,10 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr)
 	}
 
 	f2fs_mark_inode_dirty_sync(inode);
+
+	/* inode change will produce dirty node pages flushed by checkpoint */
+	f2fs_balance_fs(F2FS_I_SB(inode), true);
+
 	return err;
 }