ext2fs_truncate
int ext2fs_truncate(struct vnode *, off_t, int, kauth_cred_t);
error = ext2fs_truncate(vp, (off_t)0, 0, NOCRED);
(void) ext2fs_truncate(ovp, osize, ioflag & IO_SYNC,
error = ext2fs_truncate(dvp, (off_t)ulr->ulr_endoff, IO_SYNC,
(void) ext2fs_truncate(vp, osize, ioflag & IO_SYNC, cred);
error = ext2fs_truncate(tvp, (off_t)0, IO_SYNC, cred);
error = ext2fs_truncate(vp, vap->va_size, 0, cred);
error = ext2fs_truncate(vp, (off_t)0, IO_SYNC, cnp->cn_cred);