[Devel] [PATCH rh9] ovl: Resurrect ability to mount overlayfs in nested userns

[Pavel Tikhomirov]

Looks good.

On 10.08.2022 19:25, Konstantin Khorenko wrote:
> In vz7 mounting overlayfs in nested userns was prohibited and
> we used FS_VIRTUALIZED | FS_VE_MOUNT fs_flags to allow mounting it
> inside top Container userns.
> 
> In vz9 kernel mounting overlayfs in nested userns is enabled already:
> ms commit 459c7c565ac3 ("ovl: unprivieged mounts")
> 
> So now we should not prohibit mounting ovl in nested user namespaces
> inside a Container.
> 
> Fixes: 568f747791c7 ("fs: Mask appropriate filesystems FS_VIRTUALIZED")
> Fixes: 90df7a5ce836 ("ve/fs/overlay: allow overlayfs to be used inside a
> Container")
> 

Reviewed-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>

> Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
> ---
>   fs/overlayfs/super.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index d85596325846..a2526825724c 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -2197,10 +2197,9 @@ static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
>   static struct file_system_type ovl_fs_type = {
>   	.owner		= THIS_MODULE,
>   	.name		= "overlay",
> -	.fs_flags	= FS_USERNS_MOUNT,
> +	.fs_flags	= FS_USERNS_MOUNT | FS_VIRTUALIZED,
>   	.mount		= ovl_mount,
>   	.kill_sb	= kill_anon_super,
> -	.fs_flags	= FS_VIRTUALIZED | FS_VE_MOUNT,
>   };
>   MODULE_ALIAS_FS("overlay");
>   

-- 
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.