[$] Extended attributes for special files

The Linux extended-attribute mechanism allows the attachment of metadata tofiles within a filesystem. It tends to be little used - at least, in theabsence of a security module like SELinux. There is interest in how theseattributes work, though, as evidenced by the discussions that havefollowed the posting of revisions of thispatch by Vivek Goyal, which seeks to make a seemingly small change tothe rules regarding extended attributes and special files.