__xfs_refcount_add
__xfs_refcount_add(tp, XFS_REFCOUNT_INCREASE, isrt, PREV->br_startblock,
__xfs_refcount_add(tp, XFS_REFCOUNT_DECREASE, isrt, PREV->br_startblock,
__xfs_refcount_add(tp, XFS_REFCOUNT_ALLOC_COW, isrt, fsb, len);
__xfs_refcount_add(tp, XFS_REFCOUNT_FREE_COW, isrt, fsb, len);