set_closure_fn
set_closure_fn(cl, bch_data_insert_error, op->wq);
set_closure_fn(cl, NULL, NULL);
set_closure_fn(&dc->disk.cl, cached_dev_flush, system_percpu_wq);
set_closure_fn(&d->cl, flash_dev_flush, system_percpu_wq);
set_closure_fn(&c->cl, cache_set_free, system_percpu_wq);
set_closure_fn(&c->caching, __cache_set_unregister, system_percpu_wq);
set_closure_fn(_cl, _fn, _wq); \
set_closure_fn(_cl, _fn, _wq); \
set_closure_fn(_cl, _destructor, NULL); \
set_closure_fn(cl, closure_sync_fn, NULL);