l9p_sizeof_stat
uint16_t l9p_sizeof_stat(struct l9p_stat *stat, enum l9p_version version);
size = l9p_sizeof_stat(stat, version) - 2;
uint16_t size = l9p_sizeof_stat(&fcall->rstat.stat,
uint16_t size = l9p_sizeof_stat(st, conn->lc_version);