Function abd_alloc_linear

freebsd/contrib/openzfs/module/zfs/abd.c:248–272

* Allocate an ABD that must be linear, along with its own underlying data * buffer. Only use this when it would be very annoying to write your ABD * consumer with a scattered ABD. */

 * consumer with a scattered ABD.
 */
abd_t *
abd_alloc_linear(size_t size, boolean_t is_metadata)
{
	abd_t *abd = abd_alloc_struct(0);

	VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);

	abd->abd_flags = ABD_FLAG_LINEAR | ABD_FLAG_OWNER;
	if (is_metadata) {
		abd->abd_flags |= ABD_FLAG_META;
	}
	abd->abd_size = size;
	abd->abd_parent = NULL;
	zfs_refcount_create(&abd->abd_children);

	if (is_metadata) {
		ABD_LINEAR_BUF(abd) = zio_buf_alloc(size);
	} else {
		ABD_LINEAR_BUF(abd) = zio_data_buf_alloc(size);
	}

	abd_update_linear_stats(abd, ABDSTAT_INCR);

	return (abd);
}

static void
abd_free_linear(abd_t *abd)