ovl: port to vfs{g,u}id_t and associated helpers

A while ago we introduced a dedicated vfs{g,u}id_t type in commit
1e5267cd ("mnt_idmapping: add vfs{g,u}id_t"). We already switched
over a good part of the VFS. Ultimately we will remove all legacy
idmapped mount helpers that operate only on k{g,u}id_t in favor of the
new type safe helpers that operate on vfs{g,u}id_t.

Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs/overlayfs/util.c

@@ -1104,13 +1104,18 @@ void ovl_copyattr(struct inode *inode)
 	struct path realpath;
 	struct inode *realinode;
 	struct user_namespace *real_mnt_userns;
+	vfsuid_t vfsuid;
+	vfsgid_t vfsgid;
 
 	ovl_i_path_real(inode, &realpath);
 	realinode = d_inode(realpath.dentry);
 	real_mnt_userns = mnt_user_ns(realpath.mnt);
 
-	inode->i_uid = i_uid_into_mnt(real_mnt_userns, realinode);
-	inode->i_gid = i_gid_into_mnt(real_mnt_userns, realinode);
+	vfsuid = i_uid_into_vfsuid(real_mnt_userns, realinode);
+	vfsgid = i_gid_into_vfsgid(real_mnt_userns, realinode);
+
+	inode->i_uid = vfsuid_into_kuid(vfsuid);
+	inode->i_gid = vfsgid_into_kgid(vfsgid);
 	inode->i_mode = realinode->i_mode;
 	inode->i_atime = realinode->i_atime;
 	inode->i_mtime = realinode->i_mtime;