[Devel] [PATCH RHEL9 COMMIT] ovl: Resurrect ability to mount overlayfs in nested userns

[Konstantin Khorenko]

The commit is pushed to "branch-rh9-5.14.0-70.13.1.vz9.16.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh9-5.14.0-70.13.1.vz9.16.7
------>
commit aa9eeb04e4929cac9bd12e68748645378ffc09eb
Author: Konstantin Khorenko <khorenko at virtuozzo.com>
Date:   Wed Aug 10 19:19:39 2022 +0300

    ovl: Resurrect ability to mount overlayfs in nested userns
    
    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")
    
    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");