Function vdev_uberblock_sync

freebsd/contrib/openzfs/module/zfs/vdev_label.c:1634–1680

* Write the uberblock to all labels of all leaves of the specified vdev. */

 * Write the uberblock to all labels of all leaves of the specified vdev.
 */
static void
vdev_uberblock_sync(zio_t *zio, uint64_t *good_writes,
    uberblock_t *ub, vdev_t *vd, int flags)
{
	for (uint64_t c = 0; c < vd->vdev_children; c++) {
		vdev_uberblock_sync(zio, good_writes,
		    ub, vd->vdev_child[c], flags);
	}

	if (!vd->vdev_ops->vdev_op_leaf)
		return;

	if (!vdev_writeable(vd))
		return;

	/*
	 * There's no need to write uberblocks to a distributed spare, they
	 * are already stored on all the leaves of the parent dRAID.  For
	 * this same reason vdev_uberblock_load_impl() skips distributed
	 * spares when reading uberblocks.
	 */
	if (vd->vdev_ops == &vdev_draid_spare_ops)
		return;

	/* If the vdev was expanded, need to copy uberblock rings. */
	if (vd->vdev_state == VDEV_STATE_HEALTHY &&
	    vd->vdev_copy_uberblocks == B_TRUE) {
		vdev_copy_uberblocks(vd);
		vd->vdev_copy_uberblocks = B_FALSE;
	}

	int m = spa_multihost(vd->vdev_spa) ? MMP_BLOCKS_PER_LABEL : 0;
	int n = ub->ub_txg % (VDEV_UBERBLOCK_COUNT(vd) - m);

	/* Copy the uberblock_t into the ABD */
	abd_t *ub_abd = abd_alloc_for_io(VDEV_UBERBLOCK_SIZE(vd), B_TRUE);
	abd_zero(ub_abd, VDEV_UBERBLOCK_SIZE(vd));
	abd_copy_from_buf(ub_abd, ub, sizeof (uberblock_t));

	for (int l = 0; l < VDEV_LABELS; l++)
		vdev_label_write(zio, vd, l, ub_abd,
		    VDEV_UBERBLOCK_OFFSET(vd, n), VDEV_UBERBLOCK_SIZE(vd),
		    vdev_uberblock_sync_done, good_writes,
		    flags | ZIO_FLAG_DONT_PROPAGATE);

	abd_free(ub_abd);
}

/* Sync the uberblocks to all vdevs in svd[] */
static int