Function vdev_label_init

freebsd/contrib/openzfs/module/zfs/vdev_label.c:964–1190

* Initialize a vdev label. We check to make sure each leaf device is not in * use, and writable. We put down an initial label which we will later * overwrite with a complete label. Note that it's important to do this * sequentially, not in parallel, so that we catch cases of multiple use of the * same leaf vdev in the vdev we're creating -- e.g. mirroring a disk with * itself. */

 * itself.
 */
int
vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
{
	spa_t *spa = vd->vdev_spa;
	nvlist_t *label;
	vdev_phys_t *vp;
	abd_t *vp_abd;
	abd_t *bootenv;
	uberblock_t *ub;
	abd_t *ub_abd;
	zio_t *zio;
	char *buf;
	size_t buflen;
	int error;
	uint64_t spare_guid = 0, l2cache_guid = 0;
	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;

	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);

	for (int c = 0; c < vd->vdev_children; c++)
		if ((error = vdev_label_init(vd->vdev_child[c],
		    crtxg, reason)) != 0)
			return (error);

	/* Track the creation time for this vdev */
	vd->vdev_crtxg = crtxg;

	if (!vd->vdev_ops->vdev_op_leaf || !spa_writeable(spa))
		return (0);

	/*
	 * Dead vdevs cannot be initialized.
	 */
	if (vdev_is_dead(vd))
		return (SET_ERROR(EIO));

	/*
	 * Determine if the vdev is in use.
	 */
	if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPLIT &&
	    vdev_inuse(vd, crtxg, reason, &spare_guid, &l2cache_guid))
		return (SET_ERROR(EBUSY));

	/*
	 * If this is a request to add or replace a spare or l2cache device
	 * that is in use elsewhere on the system, then we must update the
	 * guid (which was initialized to a random value) to reflect the
	 * actual GUID (which is shared between multiple pools).
	 */
	if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_L2CACHE &&
	    spare_guid != 0ULL) {
		uint64_t guid_delta = spare_guid - vd->vdev_guid;

		vd->vdev_guid += guid_delta;

		for (vdev_t *pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
			pvd->vdev_guid_sum += guid_delta;