coda_readdir
struct coda_readdir_in coda_readdir;
struct coda_readdir_out coda_readdir;
DECL(coda_readdir); /* sets Isize & Osize */
ALLOC(coda_readdir); /* sets inp & outp */
{ &vop_readdir_desc, coda_readdir }, /* readdir */
int coda_readdir(void *);