ovl: check for ->listxattr() support

We have decoupled vfs_listxattr() from IOP_XATTR. Instead we just need
to check whether inode->i_op->listxattr is implemented.

Cc: linux-unionfs@vger.kernel.org
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

fs/overlayfs/copy_up.c

@@ -81,8 +81,7 @@ int ovl_copy_xattr(struct super_block *sb, const struct path *oldpath, struct de
 	int error = 0;
 	size_t slen;
 
-	if (!(old->d_inode->i_opflags & IOP_XATTR) ||
-	    !(new->d_inode->i_opflags & IOP_XATTR))
+	if (!old->d_inode->i_op->listxattr || !new->d_inode->i_op->listxattr)
 		return 0;
 
 	list_size = vfs_listxattr(old, NULL, 0);