mapped-devices: luks: Adjust to support extra arguments.

Fixes <https://issues.guix.gnu.org/70826>.

When using ‘luks-device-mapping-with-options’, procedures such as
‘operating-system-boot-mapped-devices’ would fail to identify LUKS
mapped devices because they would check whether the mapped device type
is ‘eq?’ to ‘luks-device-mapping’.

This addresses that by ensuring mapped devices are always of the
‘luks-device-mapping’ type, even when different options are used.

* gnu/system/mapped-devices.scm (close-luks-device): Add #:rest.
(luks-device-mapping-with-options): Deprecate.
* gnu/tests/install.scm (%encrypted-home-os-key-file): Update
accordingly.
* doc/guix.texi (Mapped Devices): Document use of the ‘arguments’ field
of ‘luks-device-mapping’.  Remove ‘luks-device-mapping-with-options’
documentation.
(Bootloader Configuration): Update example with key file in extra
initrd.

Change-Id: I5442908cb8ef4e3891dbb053cccf5e42b895486f
Reported-by: Tadhg McDonald-Jensen <tadhgmister@gmail.com>

doc/guix.texi

@@ -18641,6 +18641,9 @@ This must be a @code{mapped-device-kind} object, which specifies how
 @item arguments
 This is a list of arguments specific to @var{type} that are passed to
 its @code{open}, @code{close}, and @code{check} procedures.
+
+As an example, @code{luks-device-mapping} supports keyword
+arguments---see below for details.
 @end table
 @end deftp
 
@@ -18648,15 +18651,13 @@ its @code{open}, @code{close}, and @code{check} procedures.
 This 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 kernel module.
-@end defvar
 
-@deffn {Procedure} luks-device-mapping-with-options [#:key-file #:allow-discards?]
+The following options may be passed @i{via} the @code{arguments} field
-Return a @code{luks-device-mapping} object, which defines LUKS block
+of a mapped device:
-device encryption using the @command{cryptsetup} command from the
-package with the same name.  It relies on the @code{dm-crypt} Linux
-kernel module.
 
-If @code{key-file} is provided, unlocking is first attempted using that
+@table @code
+@item #:key-file
+If @code{file} is provided, unlocking is first attempted using that
 key file.  This has an advantage of not requiring a password entry, so
 it can be used (for example) to unlock RAID arrays automatically on
 boot.  If key file unlock fails, password unlock is attempted as well.
@@ -18669,19 +18670,19 @@ given location at the time of the unlock attempt.
 (mapped-device
  (source "/dev/sdb1)
  (target "data)
- (type (luks-device-mapping-with-options
+ (type luks-device-mapping)
-        #:key-file "/crypto.key")))
+ (arguments '(#:key-file "/crypto.key")))
 @end lisp
 
-
+@item #:allow-discards?
 @code{allow-discards?} allows the use of discard (TRIM) requests for the
 underlying device.  This is useful for solid state drives.  However,
 this option can have a negative security impact because it can make
 file system level operations visible on the physical device.  For more
 information, refer to the description of the @code{--allow-discards}
 option in the @code{cryptsetup-open(8)} man page.
-
+@end table
-@end deffn
+@end defvar
 
 @defvar raid-device-mapping
 This defines a RAID device, which is assembled using the @code{mdadm}
@@ -46200,19 +46201,19 @@ After it is created, you can use it in this manner:
 @lisp
 ;; Operating system with encrypted boot partition
 (operating-system
-  ...
+  @dots{}
   (bootloader (bootloader-configuration
                (bootloader grub-efi-bootloader)
                (targets '("/boot/efi"))
-               ;; Load the initrd with a key file
+               ;; Load the initrd with a key file...
                (extra-initrd "/key-file.cpio")))
   (mapped-devices
    (list (mapped-device
           (source (uuid "12345678-1234-1234-1234-123456789abc"))
           (target "my-root")
-          (type (luks-device-mapping-with-options
+          (type luks-device-mapping)
-                 ;; And use it to unlock the root device
+          ;; ... and use it to unlock the root device.
-                 #:key-file "/key-file.bin"))))))
+          (arguments '(#:key-file "/key-file.bin"))))))
 @end lisp
 
 Be careful when using this option, since pointing to a file that is not

gnu/system/mapped-devices.scm

@@ -256,7 +256,7 @@ requests is allowed for the underlying device."
                    (zero? (apply system*/tty cryptsetup
                                  cryptsetup-flags))))))))))
 
-(define (close-luks-device source targets)
+(define* (close-luks-device source targets #:rest _)
   "Return a gexp that closes TARGET, a LUKS device."
   (match targets
     ((target)
@@ -296,7 +296,9 @@ requests is allowed for the underlying device."
               ((gnu build file-systems)
                #:select (find-partition-by-luks-uuid system*/tty))))))
 
-(define* (luks-device-mapping-with-options #:key key-file allow-discards?)
+(define-deprecated (luks-device-mapping-with-options #:key
+                                                     key-file allow-discards?)
+  mapped-device-arguments
   "Return a luks-device-mapping object with open modified to pass the arguments
 into the open-luks-device procedure."
   (mapped-device-kind

gnu/tests/install.scm

@@ -1078,8 +1078,8 @@ launched as a shepherd service."
     (mapped-devices (list (mapped-device
                            (source (uuid "12345678-1234-1234-1234-123456789abc"))
                            (target "the-home-device")
-                           (type (luks-device-mapping-with-options
+                           (type luks-device-mapping)
-                                  #:key-file "/key-file.bin")))))
+                           (arguments '(#:key-file "/key-file.bin")))))
     (file-systems (cons* (file-system
                            (device (file-system-label "root-fs"))
                            (mount-point "/")