ext2fs_truncate
int ext2fs_truncate(struct inode *, off_t, int, struct ucred *);
error = ext2fs_truncate(ip, (off_t)0, 0, NOCRED);
error = ext2fs_truncate(dp, (off_t)dp->i_endoff, IO_SYNC,
(void)ext2fs_truncate(ip, osize,
error = ext2fs_truncate(ip, (off_t)0, IO_SYNC, cnp->cn_cred);
error = ext2fs_truncate(ip, vap->va_size, 0, cred);
error = ext2fs_truncate(xp, (off_t)0, IO_SYNC,