Add /usr to non-unmountable list

Debian's systemd has split-usr enabled as both Debian and in principle Apertis
support both a split and a merged-usr setup. This mostly adds search paths to
system (e.g. to look at both `/bin/` and `/usr/bin`) however it also means that
if `/usr` is a mountpoint system will try to unmount it.  Unfortunately this causes
issues at shutdown for systems with a merged-usr layout as basic libraries (e.g. libc)
are located in `/usr` making it impossible to unmount.

For Apertis we don't support `/usr` being a seperate partition, the only time
`/usr` is on a mountpoint is when using ostree images (where it is a bind mount
and which use a merged-usr layout). So also add `/usr` to the list of paths that
are considered unmountable even with split-usr support enabled in systemd.

Signed-off-by: Denis Pynkin <denis.pynkin@collabora.com>

debian/patches/apertis/Add-usr-to-non-unmountable-list.patch

+From 753dadfde295b15826a414757c664c6a760e979b Mon Sep 17 00:00:00 2001
+From: Denis Pynkin <denis.pynkin@collabora.com>
+Date: Wed, 10 Mar 2021 01:58:37 +0300
+Subject: [PATCH] Add /usr to non-unmountable list
+
+Debians systemd has split-usr enabled as both Debian and in principle Apertis
+support both a split and a merged-usr setup. This mostly adds search paths to
+system (e.g. to look at both `/bin/` and `/usr/bin`) however it also means that 
+if `/usr` is a mountpoint system will try to unmount it.  Unfortunately this causes
+issues at shutdown for systems with a merged-usr layout as basic libraries (e.g. libc)
+are located in `/usr` making it impossible to unmount.
+
+For Apertis we don't support `/usr` being a seperate partition, the only time 
+`/usr` is on a mountpoint is when using ostree images (where it is a bind mount
+and which use a merged-usr layout). So also add `/usr` to the list of paths that
+are considered unmountable even with split-usr support enabled in systemd.
+
+Adding `/usr` to the non-unmountable list allows to avoid problems with
+unmounting it for Apertis images.
+
+Signed-off-by: Denis Pynkin <denis.pynkin@collabora.com>
+---
+ src/core/umount.c | 2 --
+ 1 file changed, 2 deletions(-)
+
+diff --git a/src/core/umount.c b/src/core/umount.c
+index 7af0195..26f4c11 100644
+--- a/src/core/umount.c
++++ b/src/core/umount.c
+@@ -382,9 +382,7 @@ static int delete_dm(dev_t devnum) {
+ 
+ static bool nonunmountable_path(const char *path) {
+         return path_equal(path, "/")
+-#if ! HAVE_SPLIT_USR
+                 || path_equal(path, "/usr")
+-#endif
+                 || path_startswith(path, "/run/initramfs");
+ }
+ 
+-- 
+2.25.4
+

debian/patches/series

@@ -88,3 +88,4 @@ apertis/journalctl-add-new-relinquish-and-smart-relinquish-option.patch
 apertis/units-automatically-revert-to-run-logging-on-shutdown-if-.patch
 sd-boot-fix-menu-ordering-with-boot-counting.patch
 apertis/Force-the-call-of-systemd-journal-flush-before-var-u.patch
+apertis/Add-usr-to-non-unmountable-list.patch