bio_doread
bp = *bpp = bio_doread(vp, blkno, size, 0);
bp = *bpp = bio_doread(vp, blkno, size, 0);
(void) bio_doread(vp, rablks[i], rasizes[i], B_ASYNC);
*rbpp = bio_doread(vp, blkno, size, 0);
struct buf *bio_doread(struct vnode *, daddr_t, int, int);