range_tree_swap
range_tree_swap(&msp->ms_freeing, &msp->ms_freed);
range_tree_swap(&msp->ms_freed, defer_tree);
void range_tree_swap(range_tree_t **rtsrc, range_tree_t **rtdst);
range_tree_swap(&svd->vdev_obsolete_segments,
range_tree_swap(&msp->ms_trim, &trim_tree);