zfs_fuid_find_by_domain
extern int zfs_fuid_find_by_domain(zfsvfs_t *, const char *domain,
idx = zfs_fuid_find_by_domain(zfsvfs, domain, &kdomain, B_TRUE);
idx = zfs_fuid_find_by_domain(zfsvfs, domain, &kdomain, B_TRUE);
domainid = zfs_fuid_find_by_domain(zfsvfs, domain, NULL, addok);