PHP创建目录，linux服务器下，权限问题

$oldmask = umask(0);  
mkdir("picture/$class_name/$item_no/AD",0777,true);
mkdir("picture/$class_name/$item_no/SHOW",0777,true);
mkdir("picture/$class_name/$item_no/DISCRIPTION",0777,true);
mkdir("picture/$class_name/$item_no/AD200-AUTO",0777,true);
mkdir("picture/$class_name/$item_no/AD468-AUTO",0777,true);
mkdir("picture/$class_name/$item_no/SHOW200-AUTO",0777,true);
mkdir("picture/$class_name/$item_no/SHOW468-AUTO",0777,true);
umask($oldmask);