> 
>        - There is one issue with cifs-utils left for further
>          investigation: Two fstab-mounted (remote) samba 4.2 shares,
>          formerly writable, have turned read-only - while my ascii
>          desktop has still r/w access. (As first client-side attempts
>          have not been successful yet, I will look at it another day,
>          together with the server.)

Finally I came back to my beowulf cifs issue and, as actually expected,
it was easily solvable at the client. From beowulf mount.cifs(8) for
the "SMB protocol version" option:

    The default since v4.13.5 is for the client and server to
    negotiate the highest possible version greater than or equal to
    2.1. In kernels prior to v4.13,  the  default was 1.0. For
    kernels between v4.13 and v4.13.5 the default is 3.0.

The upgrade was from kernel v4.9 to v4.19; forcing the former default
version 1.0 (vers=1.0) on mount made the shares writable again. 

Staying with the new default SMB version 3.0 (I /thought/ that I had
tried this before), mount.cifs requires the "noperm" option to pass on
the write permissions.

lessons: 1. RTFM
     2. slack configuration strikes back


lulz & libre Grüße,
Florian


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