as part of the 1989 kernel, ken wrote its beginnings with a pattern that involved a lot of repetitive typing but had the basic structure. each function had to define local pieces. i took his idea and wrapped it into the structure that's there now, which made it easier to get right in practice. i'm not certain but i remember ken's version was in the fs kernel; mine was in the regular kernel (although retrofitted to fs) and introduced the way the errors fit into system calls.
-rob
