Function l2arc_add_vdev

freebsd/contrib/openzfs/module/zfs/arc.c:9466–9526

* Add a vdev for use by the L2ARC. By this point the spa has already * validated the vdev and opened it. */

 * validated the vdev and opened it.
 */
void
l2arc_add_vdev(spa_t *spa, vdev_t *vd)
{
	l2arc_dev_t		*adddev;
	uint64_t		l2dhdr_asize;

	ASSERT(!l2arc_vdev_present(vd));

	/*
	 * Create a new l2arc device entry.
	 */
	adddev = vmem_zalloc(sizeof (l2arc_dev_t), KM_SLEEP);
	adddev->l2ad_spa = spa;
	adddev->l2ad_vdev = vd;
	/* leave extra size for an l2arc device header */
	l2dhdr_asize = adddev->l2ad_dev_hdr_asize =
	    MAX(sizeof (*adddev->l2ad_dev_hdr), 1 << vd->vdev_ashift);
	adddev->l2ad_start = VDEV_LABEL_START_SIZE + l2dhdr_asize;
	adddev->l2ad_end = VDEV_LABEL_START_SIZE + vdev_get_min_asize(vd);
	ASSERT3U(adddev->l2ad_start, <, adddev->l2ad_end);
	adddev->l2ad_hand = adddev->l2ad_start;
	adddev->l2ad_evict = adddev->l2ad_start;
	adddev->l2ad_first = B_TRUE;
	adddev->l2ad_writing = B_FALSE;
	adddev->l2ad_trim_all = B_FALSE;
	list_link_init(&adddev->l2ad_node);
	adddev->l2ad_dev_hdr = kmem_zalloc(l2dhdr_asize, KM_SLEEP);

	mutex_init(&adddev->l2ad_mtx, NULL, MUTEX_DEFAULT, NULL);
	/*
	 * This is a list of all ARC buffers that are still valid on the
	 * device.
	 */
	list_create(&adddev->l2ad_buflist, sizeof (arc_buf_hdr_t),
	    offsetof(arc_buf_hdr_t, b_l2hdr.b_l2node));

	/*
	 * This is a list of pointers to log blocks that are still present
	 * on the device.
	 */
	list_create(&adddev->l2ad_lbptr_list, sizeof (l2arc_lb_ptr_buf_t),
	    offsetof(l2arc_lb_ptr_buf_t, node));

	vdev_space_update(vd, 0, 0, adddev->l2ad_end - adddev->l2ad_hand);
	zfs_refcount_create(&adddev->l2ad_alloc);
	zfs_refcount_create(&adddev->l2ad_lb_asize);
	zfs_refcount_create(&adddev->l2ad_lb_count);

	/*
	 * Add device to global list
	 */
	mutex_enter(&l2arc_dev_mtx);
	list_insert_head(l2arc_dev_list, adddev);
	atomic_inc_64(&l2arc_ndev);
	mutex_exit(&l2arc_dev_mtx);

	/*
	 * Decide if vdev is eligible for L2ARC rebuild