xfs_dir_hook_add
int xfs_dir_hook_add(struct xfs_mount *mp, struct xfs_dir_hook *hook);
error = xfs_dir_hook_add(sc->mp, &rx->dhook);
error = xfs_dir_hook_add(sc->mp, &dl->dhook);
error = xfs_dir_hook_add(sc->mp, &pscan->dhook);
error = xfs_dir_hook_add(mp, &xnc->dhook);