bootloader: grub: Allow booting from a Btrfs subvolume.

* gnu/bootloader/grub.scm (strip-mount-point): Remove procedure.
(normalize-file): Add procedure.
(grub-configuration-file): New BTRFS-SUBVOLUME-FILE-NAME parameter.  When
defined, prepend its value to the kernel and initrd file names, using the
NORMALIZE-FILE procedure.  Adjust the call to EYE-CANDY to pass the
BTRFS-SUBVOLUME-FILE-NAME argument.  Normalize the KEYMAP file as well.
(eye-candy): Add a BTRFS-SUBVOLUME-FILE-NAME parameter, and use it, along with
the NORMALIZE-FILE procedure, to normalize the FONT-FILE and IMAGE nested
variables.  Adjust doc.
* gnu/bootloader/depthcharge.scm (depthcharge-configuration-file): Adapt.
* gnu/bootloader/extlinux.scm (extlinux-configuration-file): Likewise.
* gnu/system/file-systems.scm (btrfs-subvolume?)
(btrfs-store-subvolume-file-name): New procedures.
* gnu/system.scm (operating-system-bootcfg): Specify the Btrfs
subvolume file name the store resides on to the
`operating-system-bootcfg' procedure, using the new
BTRFS-SUBVOLUME-FILE-NAME argument.
* doc/guix.texi (File Systems): Add a Btrfs subsection to document the use of
subvolumes.
* gnu/tests/install.scm (%btrfs-root-on-subvolume-os)
(%btrfs-root-on-subvolume-os-source)
(%btrfs-root-on-subvolume-installation-script)
(%test-btrfs-root-on-subvolume-os): New variables.

1 files changed, 45 insertions, 0 deletions

diff --git a/tests/file-systems.scm b/tests/file-systems.scm
index 41f1021067..7f7c373884 100644
--- a/tests/file-systems.scm
+++ b/tests/file-systems.scm
@@ -83,4 +83,49 @@
   #f
   (alist->file-system-options '()))
 
+
+;;;
+;;; Btrfs related.
+;;;
+
+(define %btrfs-root-subvolume
+  (file-system
+    (device (file-system-label "btrfs-pool"))
+    (mount-point "/")
+    (type "btrfs")
+    (options "subvol=rootfs,compress=zstd")))
+
+(define %btrfs-store-subvolid
+  (file-system
+    (device (file-system-label "btrfs-pool"))
+    (mount-point "/gnu/store")
+    (type "btrfs")
+    (options "subvolid=10,compress=zstd")
+    (dependencies (list %btrfs-root-subvolume))))
+
+(define %btrfs-store-subvolume
+  (file-system
+    (device (file-system-label "btrfs-pool"))
+    (mount-point "/gnu/store")
+    (type "btrfs")
+    (options "subvol=/some/nested/file/name")
+    (dependencies (list %btrfs-root-subvolume))))
+
+(test-assert "btrfs-subvolume? (subvol)"
+  (btrfs-subvolume? %btrfs-root-subvolume))
+
+(test-assert "btrfs-subvolume? (subvolid)"
+  (btrfs-subvolume? %btrfs-store-subvolid))
+
+(test-equal "btrfs-store-subvolume-file-name"
+  "/some/nested/file/name"
+  (parameterize ((%store-prefix "/gnu/store"))
+    (btrfs-store-subvolume-file-name (list %btrfs-root-subvolume
+                                           %btrfs-store-subvolume))))
+
+(test-error "btrfs-store-subvolume-file-name (subvolid)"
+            (parameterize ((%store-prefix "/gnu/store"))
+              (btrfs-store-subvolume-file-name (list %btrfs-root-subvolume
+                                                     %btrfs-store-subvolid))))
+
 (test-end)