bug#37977: Mount options ignored for root file system

[Guillaume Le Vaillant]

The filesystem options declared for the root file system are apparently
ignored. This happens for a btrfs root filesystem on a LUKS volume.


Exerpt from '/etc/config.scm":

--8<---------------cut here---------------start------------->8---
(mapped-devices
  (list (mapped-device
          (source
            (uuid "ee90b2aa-97e8-4ae5-ac72-9bf9058cc949"))
          (target "cryptroot")
          (type luks-device-mapping))
        (mapped-device
          (source
            (uuid "ec9cd327-0370-4e20-baa4-254d03b1901e"))
          (target "cryptguillaume")
          (type luks-device-mapping))))
(file-systems
  (cons* (file-system
           (mount-point "/")
           (device "/dev/mapper/cryptroot")
           (type "btrfs")
           (options "autodefrag,compress=lzo")
           (dependencies mapped-devices))
         (file-system
           (mount-point "/home/guillaume")
           (device "/dev/mapper/cryptguillaume")
           (type "btrfs")
           (options "autodefrag,compress=lzo")
           (dependencies mapped-devices))
         %base-file-systems))
--8<---------------cut here---------------end--------------->8---


Exerpt from '/etc/fstab':

--8<---------------cut here---------------start------------->8---
/dev/mapper/cryptroot / btrfs autodefrag,compress=lzo   
/dev/mapper/cryptguillaume /home/guillaume btrfs autodefrag,compress=lzo
--8<---------------cut here---------------end--------------->8---


Exerpt from '/etc/mtab':

--8<---------------cut here---------------start------------->8---
/dev/mapper/cryptroot / btrfs
  rw,relatime,ssd,space_cache,subvolid=5,subvol=/
  0 0

/dev/mapper/cryptguillaume /home/guillaume btrfs
  rw,relatime,compress=lzo,ssd,space_cache,autodefrag,subvolid=5,subvol=/
  0 0

/dev/mapper/cryptroot /gnu/store btrfs
  ro,relatime,ssd,space_cache,subvolid=5,subvol=/gnu/store
  0 0
--8<---------------cut here---------------end--------------->8---

Here we see that the options 'autodefrag' and 'compress=lzo' have
disappeared on the root filesystem. Maybe it has something to do with
the new '/gnu/store' subvolume that appeared?