cg_blks
cg_blks(&sblock, &acg, cbtocylno(&sblock, d))
cg_blks(&sblock, &acg, cbtocylno(&sblock, d))
cg_blks(&sblock, &acg, cbtocylno(&sblock, d))
cg_blks(fs, cgp, cylno)[cbtorpos(fs, bno)]--;
cg_blks(fs, cgp, i)[cbtorpos(fs, bno)]++;
cg_blks(fs, cgp, i)[cbtorpos(fs, bbase)]++;