gnu: eudev: Fix optical discs detection/auto-mounting.

* gnu/packages/patches/eudev-removable-devices-polling.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.
* gnu/packages/linux.scm (eudev-fixed): New fixed package.
(eudev) [replacement]: Use it.

Fixes: <https://issues.guix.gnu.org/35584>
Change-Id: I26045c99506eda1b748011825b2049057cd5394f

3 files changed, 52 insertions, 0 deletions

diff --git a/gnu/local.mk b/gnu/local.mk
index f6f95bbf10b..e25fcc115be 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1215,6 +1215,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/elm-ghc9.2.patch	\
   %D%/packages/patches/elm-offline-package-registry.patch	\
   %D%/packages/patches/elm-reactor-static-files.patch		\
+  %D%/packages/patches/eudev-removable-devices-polling.patch	\
   %D%/packages/patches/emacs-all-the-icons-remove-duplicate-rs.patch	\
   %D%/packages/patches/emacs-bash-completion-preserve-exit-code.patch	\
   %D%/packages/patches/emacs-bash-completion-preserve-ps1.patch	\
diff --git a/gnu/packages/linux.scm b/gnu/packages/linux.scm
index deb44029480..5903d4e7c11 100644
--- a/gnu/packages/linux.scm
+++ b/gnu/packages/linux.scm
@@ -4923,6 +4923,7 @@ to the in-kernel OOM killer.")
   (package
     (name "eudev")
     (version "3.2.14")
+    (replacement eudev-fixed)
     (source (origin
               (method git-fetch)
               (uri (git-reference (url "https://github.com/eudev-project/eudev")
@@ -5032,6 +5033,17 @@ device nodes from /dev/, handles hotplug events and loads drivers at boot
 time.")
     (license license:gpl2+)))
 
+(define eudev-fixed
+  (package
+    (inherit eudev)
+    (source
+     (let ((base-source (package-source eudev)))
+       (origin
+         (inherit base-source)
+         (patches
+          (append (search-patches "eudev-removable-devices-polling.patch")
+                  (origin-patches base-source))))))))
+
 (define-public python-evdev
   (package
     (name "python-evdev")
diff --git a/gnu/packages/patches/eudev-removable-devices-polling.patch b/gnu/packages/patches/eudev-removable-devices-polling.patch
new file mode 100644
index 00000000000..51a7f6a0be4
--- /dev/null
+++ b/gnu/packages/patches/eudev-removable-devices-polling.patch
@@ -0,0 +1,39 @@
+Upstream-status: https://github.com/systemd/systemd/pull/37336
+Upstream-status: https://github.com/eudev-project/eudev/pull/294
+
+The existing rule would only be effective when the block drivers are compiled
+as modules as opposed to being builtin.  On some systems such as Guix System,
+the 'sr_mod' driver for optical discs is builtin the kernel instead of a
+module, and the absence of polling means there are no uevents emitted for
+udisks to act on.
+
+This change was originally contributed to Debian by Martin Pitt to fix
+<https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=713877>, later removed as it
+was deemed no longer needed.  It appears still useful on eudev and elogind
+systems like Guix System and others.
+
+* rules.d/60-block.rules: Apply kernel polling to all removable devices instead
+of just those of the block category handled by a kernel module.
+---
+ rules.d/60-block.rules | 3 +--
+ 1 file changed, 1 insertion(+), 2 deletions(-)
+
+diff --git a/rules.d/60-block.rules b/rules.d/60-block.rules
+index c3bf32eb83..cc1eb7055e 100644
+--- a/rules/60-block.rules
++++ b/rules/60-block.rules
+@@ -1,8 +1,7 @@
+ # do not edit this file, it will be overwritten on update
+ 
+ # enable in-kernel media-presence polling
+-ACTION=="add", SUBSYSTEM=="module", KERNEL=="block", ATTR{parameters/events_dfl_poll_msecs}=="0", \
+-  ATTR{parameters/events_dfl_poll_msecs}="2000"
++ACTION=="add", ATTR{removable}=="1", ATTR{events_poll_msecs}=="-1", ATTR{events_poll_msecs}="2000"
+ 
+ # forward scsi device event to corresponding block device
+ ACTION=="change", SUBSYSTEM=="scsi", ENV{DEVTYPE}=="scsi_device", TEST=="block", ATTR{block/*/uevent}="change"
+
+base-commit: 0e0d3ed93a4e816f8ca5efb3760ceb640fea11bc
+-- 
+2.49.0
+