[PATCH container] fix #7271: exclude non-volume mountpoints from attribute preservation

[Daniel Kral <d.kral@proxmox.com>]

The commit 0db5595 (mountpoint_insert_staged: inherit attributes if
directory already exists) allows preserving attributes of the underlying
directory that is used as the mount target. Subsequently, the commit
abebdaa (fix #7267: do not inherit host attributes for rootfs) excludes
the rootdir with the $keep_attrs argument from this preservation.

As bind mountpoints might not support chaning the file permissions
and/or ownership, e.g. NFS shares, containers with such bind mounts fail
to start. Therefore, further exclude any non-volume mountpoints as these
are managed externally.

Signed-off-by: Daniel Kral <d.kral@proxmox.com>
---
Tested this with a debian container and a volume mountpoint, a
bind-mounted subdirectory on the host and a bind-mounted NFS share.

 src/PVE/LXC.pm            | 6 +++++-
 src/lxc-pve-prestart-hook | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/PVE/LXC.pm b/src/PVE/LXC.pm
index b45490b..6cdc80e 100644
--- a/src/PVE/LXC.pm
+++ b/src/PVE/LXC.pm
@@ -2473,7 +2473,11 @@ sub mountpoint_hotplug : prototype($$$$$) {
         chdir('/')
             or die "failed to change root directory within the container's mount namespace: $!\n";
 
-        mountpoint_insert_staged($mount_fd, undef, $mp->{mp}, $opt, $root_uid, $root_gid, 1);
+        my $keep_attrs = $mp->{type} eq 'volume';
+
+        mountpoint_insert_staged(
+            $mount_fd, undef, $mp->{mp}, $opt, $root_uid, $root_gid, $keep_attrs,
+        );
     });
 }
 
diff --git a/src/lxc-pve-prestart-hook b/src/lxc-pve-prestart-hook
index d264ab9..f900c12 100755
--- a/src/lxc-pve-prestart-hook
+++ b/src/lxc-pve-prestart-hook
@@ -100,7 +100,7 @@ PVE::LXC::Tools::lxc_hook(
                 # Mount relative to the rootdir fd.
                 $dest_base_fd = $rootdir_fd;
                 $dest_dir = './' . $mountpoint->{mp};
-                $keep_attrs = 1;
+                $keep_attrs = $mountpoint->{type} eq 'volume';
             } else {
                 # Assert that 'rootfs' is the first one:
                 die "foreach_mount() error\n" if $opt ne 'rootfs';
-- 
2.47.3