Function l2arc_dev_hdr_update

freebsd/contrib/openzfs/module/zfs/arc.c:10352–10390

* Creates a zio to update the device header on an l2arc device. */

 * Creates a zio to update the device header on an l2arc device.
 */
void
l2arc_dev_hdr_update(l2arc_dev_t *dev)
{
	l2arc_dev_hdr_phys_t	*l2dhdr = dev->l2ad_dev_hdr;
	const uint64_t		l2dhdr_asize = dev->l2ad_dev_hdr_asize;
	abd_t			*abd;
	int			err;

	VERIFY(spa_config_held(dev->l2ad_spa, SCL_STATE_ALL, RW_READER));

	l2dhdr->dh_magic = L2ARC_DEV_HDR_MAGIC;
	l2dhdr->dh_version = L2ARC_PERSISTENT_VERSION;
	l2dhdr->dh_spa_guid = spa_guid(dev->l2ad_vdev->vdev_spa);
	l2dhdr->dh_vdev_guid = dev->l2ad_vdev->vdev_guid;
	l2dhdr->dh_log_entries = dev->l2ad_log_entries;
	l2dhdr->dh_evict = dev->l2ad_evict;
	l2dhdr->dh_start = dev->l2ad_start;
	l2dhdr->dh_end = dev->l2ad_end;
	l2dhdr->dh_lb_asize = zfs_refcount_count(&dev->l2ad_lb_asize);
	l2dhdr->dh_lb_count = zfs_refcount_count(&dev->l2ad_lb_count);
	l2dhdr->dh_flags = 0;
	l2dhdr->dh_trim_action_time = dev->l2ad_vdev->vdev_trim_action_time;
	l2dhdr->dh_trim_state = dev->l2ad_vdev->vdev_trim_state;
	if (dev->l2ad_first)
		l2dhdr->dh_flags |= L2ARC_DEV_HDR_EVICT_FIRST;

	abd = abd_get_from_buf(l2dhdr, l2dhdr_asize);

	err = zio_wait(zio_write_phys(NULL, dev->l2ad_vdev,
	    VDEV_LABEL_START_SIZE, l2dhdr_asize, abd, ZIO_CHECKSUM_LABEL, NULL,
	    NULL, ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_CANFAIL, B_FALSE));

	abd_put(abd);

	if (err != 0) {
		zfs_dbgmsg("L2ARC IO error (%d) while writing device header, "
		    "vdev guid: %llu", err, dev->l2ad_vdev->vdev_guid);
	}
}

/*
 * Commits a log block to the L2ARC device. This routine is invoked from