clrbit
#define clrbmap(blkno) clrbit(blockmap, blkno)
#define clrbusy(blkno) clrbit(busymap, blkno)
#define clrbmap(blkno) clrbit(blockmap, blkno)
clrbit(cg_inosused(cgp), ino % sblock.fs_ipg);
clrbit(cg_blksfree(cgp),
clrbit(cg_blksfree(&acg), bit+j);
clrbit(cg_blksfree(&acg), cfp->ofrag - cgbase(&sblock, 0));
clrbit(bitmap, rel);
clrbit(blksfree, bno + i);
clrbit(iused, inot);
clrbit(blksfree, bno + i);
clrbit(asc->asc_keymap, keyix);
clrbit(asc->asc_keymap, keyix+64);
clrbit(asc->asc_keymap, keyix+32);
clrbit(asc->asc_keymap, keyix+32+64);