Subject: [bug#77499] [PATCH] mapped-devices/luks: Support extra options.

From: Maxim Cournoyer <[email-masked]>
Date: Sat, 26 Apr 2025 22:16:43 +0900

Hi,

45mg <[email-masked]> writes:

> Allow passing extra options to the 'cryptsetup open' command.
>
> * gnu/system/mapped-devices.scm (luks-device-mapping-with-options):
> [#:extra-options]: New argument.
> (open-luks-device): Use it.
> * doc/guix.texi (Mapped Devices): Document it.
> * gnu/tests/install.scm (%test-encrypted-root-extra-options-os): New
> test for it, as well as the previously untested #:allow-discards?
> option.
> (%encrypted-root-extra-options-os): New os declaration for the test.

Sounds good.

> Change-Id: Ia9fd129d1c66cbf27abdd3064d59188083465247
> ---
> CCing everyone who worked on the allow-discards option - this change is very
> similar.
>
> %encrypted-root-extra-options-os is copied from %encrypted-root-os; only
> the mapped-devices field is changed. I wish I could avoid this code
> duplication by having `(inherit %encrypted-root-os)` in the os
> definition, but when I do that, the test fails with this error in the
> build log:
>
> /mnt/etc/config.scm:1:100: error: %encrypted-root-os: unbound variable
>
> Any chance you Guile wizards know how to make this work?

I think I've probably banged my head on this at some point but don't
have an immediate idea.

>
>  doc/guix.texi                 | 20 ++++++++++-
>  gnu/system/mapped-devices.scm | 25 ++++++++-----
>  gnu/tests/install.scm         | 68 +++++++++++++++++++++++++++++++++++
>  3 files changed, 104 insertions(+), 9 deletions(-)
>
> diff --git a/doc/guix.texi b/doc/guix.texi
> index bcb1f9d9cf..9cd1304522 100644
> --- a/doc/guix.texi
> +++ b/doc/guix.texi
> @@ -18461,7 +18461,7 @@ Mapped Devices
>  @code{dm-crypt} Linux kernel module.
>  @end defvar
>  
> -@deffn {Procedure} luks-device-mapping-with-options [#:key-file #:allow-discards?]
> +@deffn {Procedure} luks-device-mapping-with-options [#:key-file #:allow-discards? #:extra-options]

Was there a way to break a line in Texinfo?

>  Return a @code{luks-device-mapping} object, which defines LUKS block
>  device encryption using the @command{cryptsetup} command from the
>  package with the same name.  It relies on the @code{dm-crypt} Linux
> @@ -18492,6 +18492,24 @@ Mapped Devices
>  information, refer to the description of the @code{--allow-discards}
>  option in the @code{cryptsetup-open(8)} man page.
>  
> +@code{extra-options} may be used to specify a list of additional
> +command-line options for the @code{cryptsetup open} command.  See the
> +@code{cryptsetup-open(8)} man page for a list of supported options.
> +
> +For example, here is how you could specify the
> +@code{--perf-no_read_workqueue} and @code{--perf-no_write_workqueue}
> +options, along with @code{--allow-discards}:

For the command-line options, you can use @option{...}
(see: (info "(texinfo) @option")).

> +
> +@lisp
> +(mapped-device
> + (source "/dev/sdb1)
> + (target "data)

Your strings are double quoted only on the left side.

> + (type (luks-device-mapping-with-options
> +        #:allow-discards? #t
> +        #:extra-options '("--perf-no_read_workqueue"
> +                          "--perf-no_write_workqueue"))))
> +@end lisp
> +
>  @end deffn
>  
>  @defvar raid-device-mapping
> diff --git a/gnu/system/mapped-devices.scm b/gnu/system/mapped-devices.scm
> index 667a495570..520ade9ef8 100644
> --- a/gnu/system/mapped-devices.scm
> +++ b/gnu/system/mapped-devices.scm
> @@ -194,10 +194,12 @@ (define (check-device-initrd-modules device linux-modules location)
>  ;;; Common device mappings.
>  ;;;
>  
> -(define* (open-luks-device source targets #:key key-file allow-discards?)
> +(define* (open-luks-device source targets
> +                           #:key key-file allow-discards? extra-options)
>    "Return a gexp that maps SOURCE to TARGET as a LUKS device, using
>  'cryptsetup'.  When ALLOW-DISCARDS? is true, the use of discard (TRIM)
> -requests is allowed for the underlying device."
> +requests is allowed for the underlying device.  EXTRA-OPTIONS is a list of
> +additional options to be passed to the 'cryptsetup open' command."
>    (with-imported-modules (source-module-closure
>                            '((gnu build file-systems)
>                              (guix build utils))) ;; For mkdir-p
> @@ -238,10 +240,15 @@ (define* (open-luks-device source targets #:key key-file allow-discards?)
>               (let ((cryptsetup #$(file-append cryptsetup-static
>                                                "/sbin/cryptsetup"))
>                     (cryptsetup-flags (cons*
> -                                      "open" "--type" "luks" partition #$target
> -                                      (if #$allow-discards?
> -                                          '("--allow-discards")
> -                                          '()))))
> +                                      "open" "--type" "luks"
> +                                      (append
> +                                       (if #$allow-discards?
> +                                           '("--allow-discards")
> +                                           '())
> +                                       (if (pair? '#$extra-options)
> +                                           '#$extra-options
> +                                           '())
> +                                       (list partition #$target)))))
>                 ;; We want to fallback to the password unlock if the keyfile
>                 ;; fails.
>                 (or (and keyfile
> @@ -290,7 +297,8 @@ (define luks-device-mapping
>                ((gnu build file-systems)
>                 #:select (find-partition-by-luks-uuid system*/tty))))))
>  
> -(define* (luks-device-mapping-with-options #:key key-file allow-discards?)
> +(define* (luks-device-mapping-with-options
> +          #:key key-file allow-discards? extra-options)
>    "Return a luks-device-mapping object with open modified to pass the arguments
>  into the open-luks-device procedure."
>    (mapped-device-kind
> @@ -298,7 +306,8 @@ (define* (luks-device-mapping-with-options #:key key-file allow-discards?)
>     (open (λ (source targets)
>             (open-luks-device source targets
>                               #:key-file key-file
> -                             #:allow-discards? allow-discards?)))))
> +                             #:allow-discards? allow-discards?
> +                             #:extra-options extra-options)))))
>  
>  (define (open-raid-device sources targets)
>    "Return a gexp that assembles SOURCES (a list of devices) to the RAID device
> diff --git a/gnu/tests/install.scm b/gnu/tests/install.scm
> index a837637b18..fd9f17eb4d 100644
> --- a/gnu/tests/install.scm
> +++ b/gnu/tests/install.scm
> @@ -68,6 +68,7 @@ (define-module (gnu tests install)
>              %test-separate-home-os
>              %test-raid-root-os
>              %test-encrypted-root-os
> +            %test-encrypted-root-extra-options-os
>              %test-encrypted-home-os
>              %test-encrypted-home-os-key-file
>              %test-encrypted-root-not-boot-os
> @@ -843,6 +844,73 @@ (define %test-encrypted-root-os
>        (run-basic-test %encrypted-root-os command "encrypted-root-os"
>                        #:initialization enter-luks-passphrase)))))
>  
> +
> +;;;
> +;;; LUKS-encrypted root with extra options: --allow-discards,
> +;;; --perf-no_read_workqueue and --perf-no_write_workqueue
> +;;;
> +
> +;; Except for the 'mapped-devices' field, this is exactly the same as
> +;; %encrypted-root-os.
> +(define-os-with-source (%encrypted-root-extra-options-os
> +                        %encrypted-root-extra-options-os-source)
> +  ;; The OS we want to install.
> +  (use-modules (gnu) (gnu tests) (srfi srfi-1))
> +
> +  (operating-system
> +    (host-name "liberigilo")
> +    (timezone "Europe/Paris")
> +    (locale "en_US.UTF-8")
> +
> +    (bootloader (bootloader-configuration
> +                 (bootloader grub-bootloader)
> +                 (targets '("/dev/vdb"))))
> +
> +    ;; Note: Do not pass "console=ttyS0" so we can use our passphrase prompt
> +    ;; detection logic in 'enter-luks-passphrase'.
> +
> +    (mapped-devices (list (mapped-device
> +                           (source (uuid "12345678-1234-1234-1234-123456789abc"))
> +                           (target "the-root-device")
> +                           (type (luks-device-mapping-with-options
> +                                  #:allow-discards? #t
> +                                  #:extra-options
> +                                  '("--perf-no_read_workqueue"
> +                                    "--perf-no_write_workqueue"))))))
> +    (file-systems (cons (file-system
> +                          (device "/dev/mapper/the-root-device")
> +                          (mount-point "/")
> +                          (type "ext4"))
> +                        %base-file-systems))
> +    (users (cons (user-account
> +                  (name "charlie")
> +                  (group "users")
> +                  (supplementary-groups '("wheel" "audio" "video")))
> +                 %base-user-accounts))
> +    (services (cons (service marionette-service-type
> +                             (marionette-configuration
> +                              (imported-modules '((gnu services herd)
> +                                                  (guix combinators)))))
> +                    %base-services))))
> +
> +(define %test-encrypted-root-extra-options-os
> +  (system-test
> +   (name "encrypted-root-extra-options-os")
> +   (description
> +    "Test basic functionality of an OS installed like one would do by hand,
> +with an LUKS-encrypted root partition opened with extra options
> +(--allow-discards, --perf-no_read_workqueue and --perf-no_write_workqueue).
> +This test is expensive in terms of CPU and storage usage since we need to
> +build (current-guix) and then store a couple of full system images.")
> +   (value
> +    (mlet* %store-monad ((images (run-install %encrypted-root-extra-options-os
> +                                              %encrypted-root-extra-options-os-source
> +                                              #:script
> +                                              %encrypted-root-installation-script))
> +                         (command (qemu-command* images)))
> +      (run-basic-test %encrypted-root-os command "encrypted-root-extra-options-os"
> +                      #:initialization enter-luks-passphrase)))))

Looks good to me.  I haven't tried running it yet; if you send a v2 with
the small problem I've seen above I'll happily try it and if it passes
merge it.

-- 
Thanks,
Maxim