fusefs_file_open
error = fusefs_file_open(fmp, ip, fufh_type, flags, isdir, ap->a_p);
error = fusefs_file_open(fmp, ip, FUFH_RDONLY, O_RDONLY, 1, p);
int fusefs_file_open(struct fusefs_mnt *, struct fusefs_node *, enum fufh_type,