fdiscard
int fdiscard(int, off_t, off_t);
FILLOP(fdiscard, FDISCARD);
} else if (fdiscard(fd, first_byte, discard_size) != 0)
PUFFS_MSG_VARS(vn, fdiscard);
PUFFS_MSG_ALLOC(vn, fdiscard);
PUFFS_MSG_RELEASE(fdiscard);
__weak_alias(fdiscard,rump___sysimpl_fdiscard);