B_VNCLEAN
if (bp->b_flags & (B_VNDIRTY | B_VNCLEAN | B_HASHED)) {
bp->b_flags |= B_VNCLEAN;
if (bp->b_flags & (B_VNDIRTY | B_VNCLEAN)) {
bp->b_flags &= ~(B_VNDIRTY | B_VNCLEAN);
if (bp->b_flags & B_VNCLEAN) {
bp->b_flags &= ~B_VNCLEAN;
if ((bp->b_flags & B_VNCLEAN) == 0) {
bp->b_flags |= B_VNCLEAN;
KKASSERT((bp->b_flags & (B_HASHED|B_DELWRI|B_VNCLEAN|B_VNDIRTY)) == 0);