[debbugs-tracker] bug#31889: closed (Filesystems must not depend on device mappings?)

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Your message dated Thu, 21 Jun 2018 23:55:27 +0200
with message-id <address@hidden>
and subject line Re: bug#31889: Filesystems must not depend on device mappings?
has caused the debbugs.gnu.org bug report #31889,
regarding Filesystems must not depend on device mappings?
to be marked as done.

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31889: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=31889
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--- Begin Message --- Subject: Filesystems must not depend on device mappings? Date: Mon, 18 Jun 2018 23:11:54 +0200

If in my OS config I define some luks mappings, and define the
corresponding filesystems with dependencies on the mapped devices,
I get an error on 'guix system reconfigure'.

Example:

  (operating-system
    ...
    (mapped-devices
      (list (mapped-device ... (target "root"))))
    (file-systems
      (list (file-system (mount-point "/")
                         ...
                         (dependencies mapped-devices))))
    ...)

This will yield an error like:

  file-system-/ depends on device-mapping-root, which is not
  provided by any service

Funnily enough, one only needs to remove the 'dependencies' field to
make it work.  But this contradicts the example at:

https://www.gnu.org/software/guix/manual/html_node/Using-the-Configuration-System.html


Taylan

--- End Message ---

> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#31889: Filesystems must not depend on device mappings?
>
>
>
>
> Date: 
>
> Thu, 21 Jun 2018 23:55:27 +0200
>
>
>
>
> User-agent: 
>
> Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux)
>
>
>
>
> Hi,
>
> Taylan Kammer <address@hidden> skribis:
>
> >      (mapped-devices
> >       (list (mapped-device
> >              (source (uuid "b3d059f8-1c4f-4569-88dd-5485825b4373"))
> >              (target "guixsd")
> >              (type luks-device-mapping))
> >             (mapped-device
> >              (source (uuid "550d9258-bbbb-488c-af27-6b1fefa190ee"))
> >              (target "home")
> >              (type luks-device-mapping))))
> >      
> >      (file-systems
> >       (append
> >        (list (file-system
> >               (device "/dev/mapper/guixsd")
> >               (mount-point "/")
> >               (type "ext4")
> >               (dependencies mapped-devices))
> >              (file-system
> >               (device "/dev/mapper/home")
> >               (mount-point "/home")
> >               (type "ext4")
> >               (dependencies mapped-devices)))
> >        %base-file-systems))
>
> [...]
>
> > It results in the error message:
> >
> >     guix system: error: service 'file-system-/home' requires
> >     'device-mapping-home', which is not provided by any service
>
> [...]
>
> > It works when both '(dependencies mapped-devices)' clauses are simply
> > removed.
>
> Yes, it’s “expected”: using “/dev/mapper/xyz” as the device is enough to
> express the dependency.
>
> When passing (dependencies mapped-devices), the effect was to each file
> system depend on *both* mapped devices.  This leads to an inconsistency
> because /dev/mapper/guixsd is “needed-for-boot” (i.e., set up from the
> initrd), whereas /dev/mapper/home is not (i.e., set up as a Shepherd
> service.)
>
> The solution is to either use the /dev/mapper/xyz names in the ‘device’
> field, or to specify only the relevant mapped device in ‘dependencies’.
>
> Anyway, commit 68a58775e071d4b0e000b93ad121b6e64d161b79 fixes it by
> doing exactly what this config asks for: setting up all the mapped
> devices in the initrd.
>
> Thanks,
> Ludo’.
>
>
> --- End Message ---