nfs export causes a Failed to activate service 'org.freedesktop.UDisks2

[gebi]

Summary: udsiks2 automount failed to start after NFS export on an up to date 20.04.

Strange bug.
After installing the nfs-server with a simple export:

# /etc/exports: the access control list for filesystems which may be exported
# to NFS clients. See exports(5).
#
# Example for NFSv2 and NFSv3:
# /srv/homes hostname1(rw,sync,no_subtree_check) hostname2(ro,sync,no_subtree_check)
#
# Example for NFSv4:
# /srv/nfs4 gss/krb5i(rw,sync,fsid=0,crossmnt,no_subtree_check)
# /srv/nfs4/homes gss/krb5i(rw,sync,no_subtree_check)
#
/home/gebi/multimedia 192.168.0.1/24(rw,async)

the udisks2 daemon fails to start. With the result of a broken gnome-shell without automount:

 bus-daemon[1094]: [system] Failed to activate service 'org.freedesktop.UDisks2': timed out (service_start_timeout=25000ms)

here more in detail:

journalctl -b

Jul 31 20:30:27 gebi-desktop kernel: floppy: error 10 while reading block 0
Jul 31 20:30:29 gebi-desktop snapd[1129]: stateengine.go:150: state ensure error: persistent network error: Get https://api.snapcraft.io/api/v1/snaps/se>
Jul 31 20:30:32 gebi-desktop tracker-miner-fs[1278]: Error creating proxy: Error calling StartServiceByName for org.gtk.vfs.UDisks2VolumeMonitor: Timeou>
Jul 31 20:30:32 gebi-desktop dbus-daemon[1286]: [session uid=123 pid=1286] Activating via systemd: service name='org.gtk.vfs.GPhoto2VolumeMonitor' unit=>
Jul 31 20:30:32 gebi-desktop dbus-daemon[1094]: [system] Failed to activate service 'org.freedesktop.UDisks2': timed out (service_start_timeout=25000ms)
Jul 31 20:30:32 gebi-desktop gvfs-udisks2-vo[1816]: monitor says it's not supported
Jul 31 20:30:32 gebi-desktop gvfs-udisks2-vo[1330]: monitor says it's not supported
Jul 31 20:30:32 gebi-desktop dbus-daemon[1782]: [session uid=1000 pid=1782] Successfully activated service 'org.gtk.vfs.UDisks2VolumeMonitor'
Jul 31 20:30:32 gebi-desktop dbus-daemon[1286]: [session uid=123 pid=1286] Successfully activated service 'org.gtk.vfs.UDisks2VolumeMonitor'
Jul 31 20:30:32 gebi-desktop systemd[1254]: Starting Virtual filesystem service - digital camera monitor...
Jul 31 20:30:32 gebi-desktop systemd[1762]: Started Virtual filesystem service - disk device monitor.
Jul 31 20:30:32 gebi-desktop systemd[1254]: Started Virtual filesystem service - disk device monitor.
Jul 31 20:30:32 gebi-desktop gvfs-udisks2-vo[1816]: monitor says it's not supported
Jul 31 20:30:32 gebi-desktop gvfs-udisks2-vo[1330]: monitor says it's not supported
Jul 31 20:30:32 gebi-desktop gvfs-udisks2-vo[1816]: monitor says it's not supported
Jul 31 20:30:32 gebi-desktop gvfs-udisks2-vo[1816]: monitor says it's not supported
Jul 31 20:30:32 gebi-desktop gnome-shell[2120]: remote volume monitor with dbus name org.gtk.vfs.UDisks2VolumeMonitor is not supported
Jul 31 20:30:32 gebi-desktop tracker-extract[1277]: remote volume monitor with dbus name org.gtk.vfs.UDisks2VolumeMonitor is not supported
Jul 31 20:30:32 gebi-desktop tracker-miner-f[1779]: remote volume monitor with dbus name org.gtk.vfs.UDisks2VolumeMonitor is not supported
Jul 31 20:30:32 gebi-desktop tracker-extract[1778]: remote volume monitor with dbus name org.gtk.vfs.UDisks2VolumeMonitor is not supported
Jul 31 20:30:32 gebi-desktop dbus-daemon[1782]: [session uid=1000 pid=1782] Activating via systemd: service name='org.gtk.vfs.GPhoto2VolumeMonitor' unit>
Jul 31 20:30:32 gebi-desktop systemd[1762]: Starting Virtual filesystem service - digital camera monitor...
Jul 31 20:30:32 gebi-desktop dbus-daemon[1286]: [session uid=123 pid=1286] Successfully activated service 'org.gtk.vfs.GPhoto2VolumeMonitor'

Luckily I found the reason:

Jul 31 20:30:04 gebi-desktop blkmapd[421]: open pipe file /run/rpc_pipefs/nfs/blocklayout failed: No such file or directory

after masking this service with:

systemctl mask nfs-blkmap.service

No errors anymore and udisks2 works !???!

Seems to be realated to this:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=850464

Masking the blkmap service resolves this issue.

Thus, I suggest to set this as default.

IMHO: As novice user like I am, I needed hours to find this out and the "blkmapd - pNFS" feature is just needed in very special cases in an enterprise environment.