An important thing to realize, if you wish to use xattr, you need a filesystem that has extended attributes functionalty and also has those enabled! I lost quite a bit of time with puzzling why xattr was not working with my ext4 system, until I found that the extended attributes, by default, are not enabled.
Adding user_xattr to the mounting configuration of the filesystem where I was working fixed the problem
/dev/sdb2 /home ext4 relatime,user_xattr 0 2