cfq

static int __init cfq_init(void)
{
	int ret;


#ifdef CONFIG_CFQ_GROUP_IOSCHED
	ret = blkcg_policy_register(&blkcg_policy_cfq);
	if (ret)
		return ret;
#else
	cfq_group_idle = 0;
#endif


	ret = -ENOMEM;
	cfq_pool = KMEM_CACHE(cfq_queue, 0);
	if (!cfq_pool)
		goto err_pol_unreg;


	ret = elv_register(&iosched_cfq);
	if (ret)
		goto err_free_pool;


	return 0;


err_free_pool:
	kmem_cache_destroy(cfq_pool);
err_pol_unreg:
#ifdef CONFIG_CFQ_GROUP_IOSCHED
	blkcg_policy_unregister(&blkcg_policy_cfq);
#endif
	return ret;
}

static void __exit cfq_exit(void)
{
#ifdef CONFIG_CFQ_GROUP_IOSCHED
	blkcg_policy_unregister(&blkcg_policy_cfq);
#endif
	elv_unregister(&iosched_cfq);kmem_cache_destroy(cfq_pool);
}


module_init(cfq_init);
module_exit(cfq_exit);

#ifdef CONFIG_CFQ_GROUP_IOSCHED
static struct blkcg_policy blkcg_policy_cfq = {
	.dfl_cftypes		= cfq_blkcg_files,
	.legacy_cftypes		= cfq_blkcg_legacy_files,


	.cpd_alloc_fn		= cfq_cpd_alloc,
	.cpd_init_fn		= cfq_cpd_init,
	.cpd_free_fn		= cfq_cpd_free,
	.cpd_bind_fn		= cfq_cpd_bind,


	.pd_alloc_fn		= cfq_pd_alloc,
	.pd_init_fn		= cfq_pd_init,
	.pd_offline_fn		= cfq_pd_offline,
	.pd_free_fn		= cfq_pd_free,
	.pd_reset_stats_fn	= cfq_pd_reset_stats,
};
#endif

static struct elevator_type iosched_cfq = {
	.ops = {
		.elevator_merge_fn = 		cfq_merge,
		.elevator_merged_fn =		cfq_merged_request,
		.elevator_merge_req_fn =	cfq_merged_requests,
		.elevator_allow_bio_merge_fn =	cfq_allow_bio_merge,
		.elevator_allow_rq_merge_fn =	cfq_allow_rq_merge,
		.elevator_bio_merged_fn =	cfq_bio_merged,
		.elevator_dispatch_fn =		cfq_dispatch_requests,
		.elevator_add_req_fn =		cfq_insert_request,
		.elevator_activate_req_fn =	cfq_activate_request,
		.elevator_deactivate_req_fn =	cfq_deactivate_request,
		.elevator_completed_req_fn =	cfq_completed_request,
		.elevator_former_req_fn =	elv_rb_former_request,
		.elevator_latter_req_fn =	elv_rb_latter_request,
		.elevator_init_icq_fn =		cfq_init_icq,
		.elevator_exit_icq_fn =		cfq_exit_icq,
		.elevator_set_req_fn =		cfq_set_request,
		.elevator_put_req_fn =		cfq_put_request,
		.elevator_may_queue_fn =	cfq_may_queue,
		.elevator_init_fn =		cfq_init_queue,
		.elevator_exit_fn =		cfq_exit_queue,
		.elevator_registered_fn =	cfq_registered_queue,
	},
	.icq_size	=	sizeof(struct cfq_io_cq),
	.icq_align	=	__alignof__(struct cfq_io_cq),
	.elevator_attrs =	cfq_attrs,
	.elevator_name	=	"cfq",
	.elevator_owner =	THIS_MODULE,
};

#define CFQ_ATTR(name) \
	__ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)


static struct elv_fs_entry cfq_attrs[] = {
	CFQ_ATTR(quantum),
	CFQ_ATTR(fifo_expire_sync),
	CFQ_ATTR(fifo_expire_async),
	CFQ_ATTR(back_seek_max),
	CFQ_ATTR(back_seek_penalty),
	CFQ_ATTR(slice_sync),
	CFQ_ATTR(slice_sync_us),
	CFQ_ATTR(slice_async),
	CFQ_ATTR(slice_async_us),
	CFQ_ATTR(slice_async_rq),
	CFQ_ATTR(slice_idle),
	CFQ_ATTR(slice_idle_us),
	CFQ_ATTR(group_idle),
	CFQ_ATTR(group_idle_us),
	CFQ_ATTR(low_latency),
	CFQ_ATTR(target_latency),
	CFQ_ATTR(target_latency_us),
	__ATTR_NULL
};