DBPERVBLK
if (dskread(blkbuf, INO_TO_VBA(&fs, n, inode), DBPERVBLK))
u = (u_int)(lbn - UFS_NDADDR) / n * DBPERVBLK;
if (dskread(indbuf, vbaddr, DBPERVBLK))
vbaddr = fsbtodb(&fs, addr2) + (off >> VBLKSHIFT) * DBPERVBLK;
(((x) % (fs)->fs_ipg) / (ipervblk) * DBPERVBLK))
((off) / VBLKSIZE) * DBPERVBLK)