ceph: add comments for handle_cap_flush_ack logic

	bool wake_mdsc = false;

	list_for_each_entry_safe(cf, tmp_cf, &ci->i_cap_flush_list, i_list) {

		/* Is this the one that was flushed? */

		if (cf->tid == flush_tid)

			cleaned = cf->caps;

		if (cf->caps == 0) /* capsnap */

		/* Is this a capsnap? */

		if (cf->caps == 0)

			continue;

		if (cf->tid <= flush_tid) {

			/*

			 * An earlier or current tid. The FLUSH_ACK should

			 * represent a superset of this flush's caps.

			 */

			wake_ci |= __detach_cap_flush_from_ci(ci, cf);

			list_add_tail(&cf->i_list, &to_remove);

		} else {

			/*

			 * This is a later one. Any caps in it are still dirty

			 * so don't count them as cleaned.

			 */

			cleaned &= ~cf->caps;

			if (!cleaned)

				break;