Re: [PATCH container 1/2] make mount point attribute preservation configurable

["Fabian Grünbichler" <f.gruenbichler@proxmox.com>]

On February 11, 2026 12:06 pm, Filip Schauer wrote:
> The commit 0db559517ac6 (mountpoint_insert_staged: inherit attributes if
> directory already exists) introduced automatic propagation of uid, gid,
> and mode from the target directory to the mounted filesystem. While this
> improves compatibility with some OCI images, it also caused undesired
> ownership changes on some mount points.
> 
> Since attribute preservation is not always desired, make this behavior
> configurable via a new "keepattrs" mountpoint flag. Default to disabled
> to preserve historical behavior.
> 
> Signed-off-by: Filip Schauer <f.schauer@proxmox.com>

Reviewed-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>

> ---
>  src/PVE/LXC.pm            | 4 +---
>  src/PVE/LXC/Config.pm     | 6 ++++++
>  src/lxc-pve-prestart-hook | 2 +-
>  3 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/src/PVE/LXC.pm b/src/PVE/LXC.pm
> index 41ea991..2c02e9a 100644
> --- a/src/PVE/LXC.pm
> +++ b/src/PVE/LXC.pm
> @@ -2478,10 +2478,8 @@ sub mountpoint_hotplug : prototype($$$$$) {
>          chdir('/')
>              or die "failed to change root directory within the container's mount namespace: $!\n";
>  
> -        my $keep_attrs = $mp->{type} eq 'volume';
> -
>          mountpoint_insert_staged(
> -            $mount_fd, undef, $mp->{mp}, $opt, $root_uid, $root_gid, $keep_attrs,
> +            $mount_fd, undef, $mp->{mp}, $opt, $root_uid, $root_gid, $mp->{keepattrs},
>          );
>      });
>  }
> diff --git a/src/PVE/LXC/Config.pm b/src/PVE/LXC/Config.pm
> index 6f54e9f..0090d61 100644
> --- a/src/PVE/LXC/Config.pm
> +++ b/src/PVE/LXC/Config.pm
> @@ -987,6 +987,12 @@ my $mp_desc = {
>          verbose_description => "Path to the mount point as seen from inside the container.\n\n"
>              . "NOTE: Must not contain any symlinks for security reasons.",
>      },
> +    keepattrs => {
> +        type => 'boolean',
> +        description => 'Inherit attributes from the target path, if it exists already.',

nit: "target path" is not a term we've used here in the past.. the usual
term for this directory is "mountpoint". 

maybe s/target path/mountpoint directory/ here?

_maybe_ we could also spell out what "attributes" means here?

> +        optional => 1,
> +        default => 0,
> +    },
>  };
>  PVE::JSONSchema::register_format('pve-ct-mountpoint', $mp_desc);
>  
> diff --git a/src/lxc-pve-prestart-hook b/src/lxc-pve-prestart-hook
> index f900c12..9862509 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 = $mountpoint->{type} eq 'volume';
> +                $keep_attrs = $mountpoint->{keepattrs};
>              } else {
>                  # Assert that 'rootfs' is the first one:
>                  die "foreach_mount() error\n" if $opt ne 'rootfs';
> -- 
> 2.47.3
> 
> 
> 
> 
> 
>