XFS_DEFER_OPS_NR_BUFS
BUILD_BUG_ON(NBBY * sizeof(dres->dr_ordered) < XFS_DEFER_OPS_NR_BUFS);
if (dres->dr_bufs >= XFS_DEFER_OPS_NR_BUFS) {
struct xfs_buf *dr_bp[XFS_DEFER_OPS_NR_BUFS];