It might be interesting to build a test harness using libgfapi
(specially the handle based APIs) to load a graph with the xlator to be
test (on top of posix) and using gfapi calls to bombard fops and
notifications and callbacks from multiple threads spawned by the testing
app/framework.
Along with a fault injection, we also need a "pedantic verifier"
translator (loaded both on top and blow the testing xlator) which
inspects all params of all calls and callbacks coming out of the xlator
to "conform" by the rules (e.g lookup_cbk op_ret is either -1 or 0 ONLY,
op_errno is one of the known standard values ONLY, struct stat does not
have mtime/ctime/atime from too far ahead into the future, mkdir_cbk's
struct stat has ia_type to be IA_IFDIR ONLY etc.)