[Samba] Issues accessing ZFS-shares on Linux

[John Doe]

Hi,

I am having a really strange problem with my Samba shares on Debian
Buster. None of the users can access any shares, which reside on
ZFS-filesystem. Any other share works just fine. For example, if I
create a normal folder to /home with same permissions and replace a
ZFS-share with that, it works fine.

When accessing any ZFS-shares the following error is recorded:
Jan 08 22:39:56 punishedkorppu smbd[27893]: [2018/01/08 22:39:56.075343,
 0] ../source3/smbd/service.c:774(make_connection_snum)
Jan 08 22:39:56 punishedkorppu smbd[27893]:   canonicalize_connect_path
failed for service rex, path /tank/rex

The system in use is Debian Buster with Samba 2:4.7.3+dfsg-1 and ZoL
0.7.4-1 from Debian repo. Selinux is disabled and apparmor too.

Any ideas what might be wrong with this setup?


--- information ---

The mountpoint really is /tank/rex according to zfs list. It can also be
accessed by any user locally.

NAME                        USED  AVAIL  REFER  MOUNTPOINT
tank                       7.74T  7.24T   222K  /tank
tank/homedir               96.8G  7.24T   222K  /tank/homedir
tank/mei                   5.98G  7.24T  5.98G  /tank/mei
tank/rex                   7.64T  7.24T  11.1G  /tank/rex

Folder permissions ls -hal /tank
drwxr-xr-x  7 root  root    7 Jan  8 19:04 ./
drwxr-xr-x  1 root  root  284 Jan  8 21:07 ../
drwx------  2 rex   root    2 Jul 30 06:22 davtmp/
drwx---r-x 13 root  root   13 Sep  6 23:13 homedir/
drwxrwx--- 11 root  mei    11 Dec 24 18:35 mei/
drwxrwxrwx 12 rex   rex    20 Dec 24 19:09 rex/

smb.conf from testparm -s:

# Global parameters
[global]
        async smb echo handler = Yes
        dns proxy = No
        log file = /var/log/samba/log.%m
        map to guest = Bad User
        max log size = 1000
        obey pam restrictions = Yes
        pam password change = Yes
        panic action = /usr/share/samba/panic-action %d
        passwd chat = *Enter\snew\s*\spassword:* %n\n
*Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* .
        passwd program = /usr/bin/passwd %u
        server role = standalone server
        unix password sync = Yes
        idmap config * : backend = tdb
        aio read size = 1
        aio write size = 1
        use sendfile = Yes


[rex]
        comment = REX
        create mask = 0660
        force create mode = 0660
        force directory mode = 0770
        force group = rex
        path = /tank/rex
        read only = No
        valid users = @rex


[mei]
        comment = MEI
        create mask = 0660
        force create mode = 0660
        force directory mode = 0770
        force group = mei
        path = /tank/mei
        read only = No
        valid users = @mei


[homedir]
        comment = Homedir
        create mask = 0600
        force directory mode = 0700
        path = /tank/homedir
        read only = No