XB_BMASK
ASSERT((blk_off & XB_BMASK) == 0);
((((uintptr_t)((bp)->b_un.b_addr) & XB_BMASK) == 0) && \
(((bp)->b_bcount & XB_BMASK) == 0))
#define U_INVAL(u) (((u)->uio_loffset & (offset_t)(XB_BMASK)) || \
((u)->uio_iov->iov_len & (offset_t)(XB_BMASK)))