Function vdev_draid_metaslab_init

freebsd/contrib/openzfs/module/zfs/vdev_draid.c:1843–1859

* Align the start of the metaslab to the group width and slightly reduce * its size to a multiple of the group width. Since full stripe writes are * required by dRAID this space is unallocable. Furthermore, aligning the * metaslab start is important for vdev initialize and TRIM which both operate * on metaslab boundaries which vdev_xlate() expects to be aligned. */

 * on metaslab boundaries which vdev_xlate() expects to be aligned.
 */
static void
vdev_draid_metaslab_init(vdev_t *vd, uint64_t *ms_start, uint64_t *ms_size)
{
	vdev_draid_config_t *vdc = vd->vdev_tsd;

	ASSERT3P(vd->vdev_ops, ==, &vdev_draid_ops);

	uint64_t sz = vdc->vdc_groupwidth << vd->vdev_ashift;
	uint64_t astart = vdev_draid_get_astart(vd, *ms_start);
	uint64_t asize = ((*ms_size - (astart - *ms_start)) / sz) * sz;

	*ms_start = astart;
	*ms_size = asize;

	ASSERT0(*ms_start % sz);
	ASSERT0(*ms_size % sz);
}

/*
 * Add virtual dRAID spares to the list of valid spares. In order to accomplish