Function vdev_copy_uberblocks

freebsd/contrib/openzfs/module/zfs/vdev_label.c:1568–1616

 */

static void
vdev_copy_uberblocks(vdev_t *vd)
{
	abd_t *ub_abd;
	zio_t *write_zio;
	int locks = (SCL_L2ARC | SCL_ZIO);
	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
	    ZIO_FLAG_SPECULATIVE;

	ASSERT(spa_config_held(vd->vdev_spa, SCL_STATE, RW_READER) ==
	    SCL_STATE);
	ASSERT(vd->vdev_ops->vdev_op_leaf);

	/*
	 * No uberblocks are stored on distributed spares, they may be
	 * safely skipped when expanding a leaf vdev.
	 */
	if (vd->vdev_ops == &vdev_draid_spare_ops)
		return;

	spa_config_enter(vd->vdev_spa, locks, FTAG, RW_READER);

	ub_abd = abd_alloc_linear(VDEV_UBERBLOCK_SIZE(vd), B_TRUE);

	write_zio = zio_root(vd->vdev_spa, NULL, NULL, flags);
	for (int n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) {
		const int src_label = 0;
		zio_t *zio;

		zio = zio_root(vd->vdev_spa, NULL, NULL, flags);
		vdev_label_read(zio, vd, src_label, ub_abd,
		    VDEV_UBERBLOCK_OFFSET(vd, n), VDEV_UBERBLOCK_SIZE(vd),
		    NULL, NULL, flags);

		if (zio_wait(zio) || uberblock_verify(abd_to_buf(ub_abd)))
			abd_zero(ub_abd, VDEV_UBERBLOCK_SIZE(vd));

		for (int l = 2; l < VDEV_LABELS; l++)
			vdev_label_write(write_zio, vd, l, ub_abd,
			    VDEV_UBERBLOCK_OFFSET(vd, n),
			    VDEV_UBERBLOCK_SIZE(vd), NULL, NULL,
			    flags | ZIO_FLAG_DONT_PROPAGATE);
	}
	(void) zio_wait(write_zio);

	spa_config_exit(vd->vdev_spa, locks, FTAG);

	abd_free(ub_abd);
}

/*
 * On success, increment root zio's count of good writes.