$ zfs create -quota=1T data/timemachine

[global]
  workgroup = WORKGROUP
  security = user
  netbios name = backup
  server string = backup.your-local-domain.invalid
  hostname lookups = yes

  load printers = no
  show add printer wizard = no
  time server = yes
  map to guest = Bad User
  use mmap = yes

  dos charset = 850
  unix charset = UTF-8
  mangled names = no

  log level = 0
  vfs objects = fruit streams_xattr zfsacl

  fruit:model = MacPro
  fruit:resource = file
  fruit:metadata = netatalk

; time machines
[macbook]
  path = /data/timemachine
  read only = no
  use sendfile = yes
  browseable = no
  hosts allow = macbook.your-local-domain.invalid fe80::/10
  fruit:time machine = yes
  fruit:time machine max size = 500G
  valid users = tm

Then we can set our Macbook Pro to use the timemachine:

sudo tmutil setdestination 'smb://user:password@ip/macbook'