+#define IOCB_HAS_META		(1 << 22)

.. METADATA?

Also the fs infrastructure should probably be split from io_uring.

+/*
+ * flags for integrity meta
+ */
+#define INTEGRITY_CHK_GUARD	(1U << 0) /* enforce guard check */
+#define INTEGRITY_CHK_APPTAG	(1U << 1) /* enforce app tag check */
+#define INTEGRITY_CHK_REFTAG	(1U << 2) /* enforce ref tag check */

This gets used all over the block layer.  I don't think it should be
in an io_uring specific header even if that is the initial user.

We might also gain a bit more flexibility by splitting the userspace
API from the in-kernel flags even if there is no strong needs for that
yet.