layer: ignore ENOTSUP on setxattr

This mirrors existing behaviour within Docker or similar tools, where we
ignore lsetxattr(2) failures because there's not much you can do if the
filesystem doesn't support it.

Signed-off-by: Aleksa Sarai <asarai@suse.de>

oci/layer/tar_extract.go

@@ -154,6 +154,13 @@ func (te *TarExtractor) restoreMetadata(path string, hdr *tar.Header) error {
 				log.Warnf("rootless{%s} ignoring (usually) harmless EPERM on setxattr %q", hdr.Name, name)
 				continue
 			}
+			// We cannot do much if we get an ENOTSUPP -- this usually means
+			// that extended attributes are simply unsupported by the
+			// underlying filesystem (such as AUFS or NFS).
+			if errors.Cause(err) == unix.ENOTSUP {
+				log.Warnf("xatt{%s} ignoring ENOTSUPP on setxattr %q", hdr.Name, name)
+				continue
+			}
 			return errors.Wrapf(err, "restore xattr metadata: %s", path)
 		}
 	}