BC_NOCACHE
if (ISSET(bp->b_cflags, BC_NOCACHE) || bp->b_error != 0)
CLR(bp->b_cflags, BC_AGE|BC_BUSY|BC_NOCACHE);
SET(bp->b_cflags, BC_NOCACHE);
KASSERT((bp->b_cflags & BC_NOCACHE) == 0);
KASSERT((bp->b_flags & BC_NOCACHE) == 0);
KDASSERT(!(bp->b_cflags & BC_NOCACHE));
brelse(bp, BC_NOCACHE);
if ((bp->b_flags & BC_NOCACHE) && fs->fs_bsize <= xfersize)
brelse(bp, BC_INVAL | BC_NOCACHE);
brelse(bp, BC_NOCACHE);
bp->b_cflags |= BC_BUSY | BC_NOCACHE;
KASSERT((bp->b_flags & B_LOCKED) || (bp->b_cflags & (BC_NOCACHE | BC_INVAL)));
(tbp->b_cflags & (BC_NOCACHE | BC_INVAL)));
bp->b_cflags = BC_BUSY | BC_NOCACHE;