blk_init_queue

struct request_queue * blk_init_queue (request_fn_proc *rfn, spinlock_t *lock)
{
	return blk_init_queue_node(rfn, lock, NUMA_NO_NODE);
}
EXPORT_SYMBOL(blk_init_queue);


struct request_queue *
blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
{
	struct request_queue *uninit_q, *q;


	uninit_q = blk_alloc_queue_node(GFP_KERNEL, node_id);
	if (!uninit_q)
		return NULL;


	q = blk_init_allocated_queue(uninit_q, rfn, lock);
	if (!q)
		blk_cleanup_queue(uninit_q);


	return q;
}
EXPORT_SYMBOL(blk_init_queue_node);

struct request_queue *
blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
			
{
	if (!q)
		return NULL;

	q->fq = blk_alloc_flush_queue(q, NUMA_NO_NODE, 0);
	if (!q->fq)
		return NULL;

	if (blk_init_rl(&q->root_rl, q, GFP_KERNEL))
		goto fail;

	INIT_WORK(&q->timeout_work, blk_timeout_work);
	q->request_fn		= rfn;
	q->prep_rq_fn		= NULL;
	q->unprep_rq_fn		= NULL;
	q->queue_flags		|= QUEUE_FLAG_DEFAULT;

	/* Override internal queue lock with supplied lock pointer */
	if (lock)
		q->queue_lock		= lock;
	/*
	 * This also sets hw/phys segments, boundary and size
	 */
	blk_queue_make_request(q, blk_queue_bio);

	q->sg_reserved_size = INT_MAX;

	/* Protect q->elevator from elevator_change */
	mutex_lock(&q->sysfs_lock);

/* init elevator */
	if (elevator_init(q, NULL)) {
		mutex_unlock(&q->sysfs_lock);
		goto fail;
	}

	mutex_unlock(&q->sysfs_lock);
	return q;
fail:
	blk_free_flush_queue(q->fq);
	return NULL;
}

struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
{
	struct request_queue *q;
	int err;


	q = kmem_cache_alloc_node(blk_requestq_cachep,
				gfp_mask | __GFP_ZERO, node_id);
	if (!q)
		return NULL;


	q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask);
	if (q->id < 0)
		goto fail_q;

	q->bio_split = bioset_create(BIO_POOL_SIZE, 0);
	if (!q->bio_split)
		goto fail_id;

	q->backing_dev_info.ra_pages =
			(VM_MAX_READAHEAD * 1024) / PAGE_SIZE;
	q->backing_dev_info.capabilities = BDI_CAP_CGROUP_WRITEBACK;
	q->backing_dev_info.name = "block";
	q->node = node_id;

	err = bdi_init(&q->backing_dev_info);
	if (err)
		goto fail_split;


	setup_timer(&q->backing_dev_info.laptop_mode_wb_timer,
		    laptop_mode_timer_fn, (unsigned long) q);
	setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
	INIT_LIST_HEAD(&q->queue_head);
	INIT_LIST_HEAD(&q->timeout_list);
	INIT_LIST_HEAD(&q->icq_list);
#ifdef CONFIG_BLK_CGROUP
	INIT_LIST_HEAD(&q->blkg_list);
#endif
	INIT_DELAYED_WORK(&q->delay_work, blk_delay_work);
	kobject_init(&q->kobj, &blk_queue_ktype);
	mutex_init(&q->sysfs_lock);
	spin_lock_init(&q->__queue_lock);
	/*
	 * By default initialize queue_lock to internal lock and driver can
	 * override it later if need be.
	 */
	q->queue_lock = &q->__queue_lock;


	/*
	 * A queue starts its life with bypass turned on to avoid
	 * unnecessary bypass on/off overhead and nasty surprises during
	 * init.  The initial bypass will be finished when the queue is
	 * registered by blk_register_queue().
	 */
	q->bypass_depth = 1;
	__set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags);
	init_waitqueue_head(&q->mq_freeze_wq);
	/*
	 * Init percpu_ref in atomic mode so that it's faster to shutdown.
	 * See blk_register_queue() for details.
	 */
	if (percpu_ref_init(&q->q_usage_counter,
				blk_queue_usage_counter_release,
				PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
		goto fail_bdi;


	if (blkcg_init_queue(q))
		goto fail_ref;
	return q;


fail_ref:
	percpu_ref_exit(&q->q_usage_counter);
fail_bdi:
	bdi_destroy(&q->backing_dev_info);
fail_split:
	bioset_free(q->bio_split);
fail_id:
	ida_simple_remove(&blk_queue_ida, q->id);
fail_q:
	kmem_cache_free(blk_requestq_cachep, q);
	return NULL;
}