[PATCH 5.15.y 1/4] ovl: add ovl_upper_mnt_userns() wrapper

[Sasha Levin <sashal@kernel.org>]

From: Christian Brauner <brauner@kernel.org>

[ Upstream commit b65c20acef23cea2989c9f23414930149d38962f ]

Add a tiny wrapper to retrieve the upper mount's idmapping. Have it
return the initial idmapping until we have prepared and converted all
places to take the relevant idmapping into account. Then we can switch
on idmapped layer support by having ovl_upper_mnt_userns() return the
upper mount's idmapping.

Suggested-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Stable-dep-of: 755b5c5c9277 ("ovl: do not copy up an xattr value that was never read")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/overlayfs/ovl_entry.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index 08031638bbeec..e319e9969c3a6 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -99,6 +99,11 @@ static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)
 	return ofs->layers[0].mnt;
 }
 
+static inline struct user_namespace *ovl_upper_mnt_userns(struct ovl_fs *ofs)
+{
+	return &init_user_ns;
+}
+
 static inline struct ovl_fs *OVL_FS(struct super_block *sb)
 {
 	return (struct ovl_fs *)sb->s_fs_info;
-- 
2.53.0