block/blk-sysfs.c - maze/linux - Git at Google

 /*
  * Functions related to sysfs handling
  */
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/bio.h>
 #include <linux/blkdev.h>
 #include <linux/blktrace_api.h>

 #include "blk.h"

 struct queue_sysfs_entry {
 	struct attribute attr;
 	ssize_t (*show)(struct request_queue *, char *);
 	ssize_t (*store)(struct request_queue *, const char *, size_t);
 };

 static ssize_t
 queue_var_show(unsigned int var, char *page)
 {
 	return sprintf(page, "%d\n", var);
 }

 static ssize_t
 queue_var_store(unsigned long *var, const char *page, size_t count)
 {
 	char *p = (char *) page;

 	*var = simple_strtoul(p, &p, 10);
 	return count;
 }

 static ssize_t queue_requests_show(struct request_queue *q, char *page)
 {
 	return queue_var_show(q->nr_requests, (page));
 }

 static ssize_t
 queue_requests_store(struct request_queue *q, const char *page, size_t count)
 {
 	struct request_list *rl = &q->rq;
 	unsigned long nr;
 	int ret = queue_var_store(&nr, page, count);
 	if (nr < BLKDEV_MIN_RQ)
 		nr = BLKDEV_MIN_RQ;

 	spin_lock_irq(q->queue_lock);
 	q->nr_requests = nr;
 	blk_queue_congestion_threshold(q);

 	if (rl->count[READ] >= queue_congestion_on_threshold(q))
 		blk_set_queue_congested(q, READ);
 	else if (rl->count[READ] < queue_congestion_off_threshold(q))
 		blk_clear_queue_congested(q, READ);

 	if (rl->count[WRITE] >= queue_congestion_on_threshold(q))
 		blk_set_queue_congested(q, WRITE);
 	else if (rl->count[WRITE] < queue_congestion_off_threshold(q))
 		blk_clear_queue_congested(q, WRITE);

 	if (rl->count[READ] >= q->nr_requests) {
 		blk_set_queue_full(q, READ);
 	} else if (rl->count[READ]+1 <= q->nr_requests) {
 		blk_clear_queue_full(q, READ);
 		wake_up(&rl->wait[READ]);
 	}

 	if (rl->count[WRITE] >= q->nr_requests) {
 		blk_set_queue_full(q, WRITE);
 	} else if (rl->count[WRITE]+1 <= q->nr_requests) {
 		blk_clear_queue_full(q, WRITE);
 		wake_up(&rl->wait[WRITE]);
 	}
 	spin_unlock_irq(q->queue_lock);
 	return ret;
 }

 static ssize_t queue_ra_show(struct request_queue *q, char *page)
 {
 	int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);

 	return queue_var_show(ra_kb, (page));
 }

 static ssize_t
 queue_ra_store(struct request_queue *q, const char *page, size_t count)
 {
 	unsigned long ra_kb;
 	ssize_t ret = queue_var_store(&ra_kb, page, count);

 	q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);

 	return ret;
 }

 static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
 {
 	int max_sectors_kb = q->max_sectors >> 1;

 	return queue_var_show(max_sectors_kb, (page));
 }

 static ssize_t queue_hw_sector_size_show(struct request_queue *q, char *page)
 {
 	return queue_var_show(q->hardsect_size, page);
 }

 static ssize_t
 queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
 {
 	unsigned long max_sectors_kb,
 			max_hw_sectors_kb = q->max_hw_sectors >> 1,
 			page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
 	ssize_t ret = queue_var_store(&max_sectors_kb, page, count);

 	if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
 		return -EINVAL;

 	spin_lock_irq(q->queue_lock);
 	q->max_sectors = max_sectors_kb << 1;
 	spin_unlock_irq(q->queue_lock);

 	return ret;
 }

 static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
 {
 	int max_hw_sectors_kb = q->max_hw_sectors >> 1;

 	return queue_var_show(max_hw_sectors_kb, (page));
 }

 static ssize_t queue_nonrot_show(struct request_queue *q, char *page)
 {
 	return queue_var_show(!blk_queue_nonrot(q), page);
 }

 static ssize_t queue_nonrot_store(struct request_queue *q, const char *page,
 				  size_t count)
 {
 	unsigned long nm;
 	ssize_t ret = queue_var_store(&nm, page, count);

 	spin_lock_irq(q->queue_lock);
 	if (nm)
 		queue_flag_clear(QUEUE_FLAG_NONROT, q);
 	else
 		queue_flag_set(QUEUE_FLAG_NONROT, q);
 	spin_unlock_irq(q->queue_lock);

 	return ret;
 }

 static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
 {
 	return queue_var_show(blk_queue_nomerges(q), page);
 }

 static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
 				    size_t count)
 {
 	unsigned long nm;
 	ssize_t ret = queue_var_store(&nm, page, count);

 	spin_lock_irq(q->queue_lock);
 	if (nm)
 		queue_flag_set(QUEUE_FLAG_NOMERGES, q);
 	else
 		queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
 	spin_unlock_irq(q->queue_lock);

 	return ret;
 }

 static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page)
 {
 	unsigned int set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);

 	return queue_var_show(set != 0, page);
 }

 static ssize_t
 queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
 {
 	ssize_t ret = -EINVAL;
 #if defined(CONFIG_USE_GENERIC_SMP_HELPERS)
 	unsigned long val;

 	ret = queue_var_store(&val, page, count);
 	spin_lock_irq(q->queue_lock);
 	if (val)
 		queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
 	else
 		queue_flag_clear(QUEUE_FLAG_SAME_COMP,  q);
 	spin_unlock_irq(q->queue_lock);
 #endif
 	return ret;
 }

 static struct queue_sysfs_entry queue_requests_entry = {
 	.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
 	.show = queue_requests_show,
 	.store = queue_requests_store,
 };

 static struct queue_sysfs_entry queue_ra_entry = {
 	.attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
 	.show = queue_ra_show,
 	.store = queue_ra_store,
 };

 static struct queue_sysfs_entry queue_max_sectors_entry = {
 	.attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
 	.show = queue_max_sectors_show,
 	.store = queue_max_sectors_store,
 };

 static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
 	.attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
 	.show = queue_max_hw_sectors_show,
 };

 static struct queue_sysfs_entry queue_iosched_entry = {
 	.attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
 	.show = elv_iosched_show,
 	.store = elv_iosched_store,
 };

 static struct queue_sysfs_entry queue_hw_sector_size_entry = {
 	.attr = {.name = "hw_sector_size", .mode = S_IRUGO },
 	.show = queue_hw_sector_size_show,
 };

 static struct queue_sysfs_entry queue_nonrot_entry = {
 	.attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR },
 	.show = queue_nonrot_show,
 	.store = queue_nonrot_store,
 };

 static struct queue_sysfs_entry queue_nomerges_entry = {
 	.attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
 	.show = queue_nomerges_show,
 	.store = queue_nomerges_store,
 };

 static struct queue_sysfs_entry queue_rq_affinity_entry = {
 	.attr = {.name = "rq_affinity", .mode = S_IRUGO | S_IWUSR },
 	.show = queue_rq_affinity_show,
 	.store = queue_rq_affinity_store,
 };

 static struct attribute *default_attrs[] = {
 	&queue_requests_entry.attr,
 	&queue_ra_entry.attr,
 	&queue_max_hw_sectors_entry.attr,
 	&queue_max_sectors_entry.attr,
 	&queue_iosched_entry.attr,
 	&queue_hw_sector_size_entry.attr,
 	&queue_nonrot_entry.attr,
 	&queue_nomerges_entry.attr,
 	&queue_rq_affinity_entry.attr,
 	NULL,
 };

 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)

 static ssize_t
 queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 {
 	struct queue_sysfs_entry *entry = to_queue(attr);
 	struct request_queue *q =
 		container_of(kobj, struct request_queue, kobj);
 	ssize_t res;

 	if (!entry->show)
 		return -EIO;
 	mutex_lock(&q->sysfs_lock);
 	if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
 		mutex_unlock(&q->sysfs_lock);
 		return -ENOENT;
 	}
 	res = entry->show(q, page);
 	mutex_unlock(&q->sysfs_lock);
 	return res;
 }

 static ssize_t
 queue_attr_store(struct kobject *kobj, struct attribute *attr,
 		    const char *page, size_t length)
 {
 	struct queue_sysfs_entry *entry = to_queue(attr);
 	struct request_queue *q;
 	ssize_t res;

 	if (!entry->store)
 		return -EIO;

 	q = container_of(kobj, struct request_queue, kobj);
 	mutex_lock(&q->sysfs_lock);
 	if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
 		mutex_unlock(&q->sysfs_lock);
 		return -ENOENT;
 	}
 	res = entry->store(q, page, length);
 	mutex_unlock(&q->sysfs_lock);
 	return res;
 }

 /**
  * blk_cleanup_queue: - release a &struct request_queue when it is no longer needed
  * @kobj:    the kobj belonging of the request queue to be released
  *
  * Description:
  *     blk_cleanup_queue is the pair to blk_init_queue() or
  *     blk_queue_make_request().  It should be called when a request queue is
  *     being released; typically when a block device is being de-registered.
  *     Currently, its primary task it to free all the &struct request
  *     structures that were allocated to the queue and the queue itself.
  *
  * Caveat:
  *     Hopefully the low level driver will have finished any
  *     outstanding requests first...
  **/
 static void blk_release_queue(struct kobject *kobj)
 {
 	struct request_queue *q =
 		container_of(kobj, struct request_queue, kobj);
 	struct request_list *rl = &q->rq;

 	blk_sync_queue(q);

 	if (rl->rq_pool)
 		mempool_destroy(rl->rq_pool);

 	if (q->queue_tags)
 		__blk_queue_free_tags(q);

 	blk_trace_shutdown(q);

 	bdi_destroy(&q->backing_dev_info);
 	kmem_cache_free(blk_requestq_cachep, q);
 }

 static struct sysfs_ops queue_sysfs_ops = {
 	.show	= queue_attr_show,
 	.store	= queue_attr_store,
 };

 struct kobj_type blk_queue_ktype = {
 	.sysfs_ops	= &queue_sysfs_ops,
 	.default_attrs	= default_attrs,
 	.release	= blk_release_queue,
 };

 int blk_register_queue(struct gendisk *disk)
 {
 	int ret;

 	struct request_queue *q = disk->queue;

 	if (WARN_ON(!q))
 		return -ENXIO;

 	if (!q->request_fn)
 		return 0;

 	ret = kobject_add(&q->kobj, kobject_get(&disk_to_dev(disk)->kobj),
 			  "%s", "queue");
 	if (ret < 0)
 		return ret;

 	kobject_uevent(&q->kobj, KOBJ_ADD);

 	ret = elv_register_queue(q);
 	if (ret) {
 		kobject_uevent(&q->kobj, KOBJ_REMOVE);
 		kobject_del(&q->kobj);
 		return ret;
 	}

 	return 0;
 }

 void blk_unregister_queue(struct gendisk *disk)
 {
 	struct request_queue *q = disk->queue;

 	if (WARN_ON(!q))
 		return;

 	if (q->request_fn) {
 		elv_unregister_queue(q);

 		kobject_uevent(&q->kobj, KOBJ_REMOVE);
 		kobject_del(&q->kobj);
 		kobject_put(&disk_to_dev(disk)->kobj);
 	}
 }
	/*
	* Functions related to sysfs handling
	*/
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/bio.h>
	#include <linux/blkdev.h>
	#include <linux/blktrace_api.h>

	#include "blk.h"

	struct queue_sysfs_entry {
	struct attribute attr;
	ssize_t (show)(struct request_queue , char *);
	ssize_t (store)(struct request_queue , const char *, size_t);
	};

	static ssize_t
	queue_var_show(unsigned int var, char *page)
	{
	return sprintf(page, "%d\n", var);
	}

	static ssize_t
	queue_var_store(unsigned long var, const char page, size_t count)
	{
	char p = (char ) page;

	*var = simple_strtoul(p, &p, 10);
	return count;
	}

	static ssize_t queue_requests_show(struct request_queue q, char page)
	{
	return queue_var_show(q->nr_requests, (page));
	}

	static ssize_t
	queue_requests_store(struct request_queue q, const char page, size_t count)
	{
	struct request_list *rl = &q->rq;
	unsigned long nr;
	int ret = queue_var_store(&nr, page, count);
	if (nr < BLKDEV_MIN_RQ)
	nr = BLKDEV_MIN_RQ;

	spin_lock_irq(q->queue_lock);
	q->nr_requests = nr;
	blk_queue_congestion_threshold(q);

	if (rl->count[READ] >= queue_congestion_on_threshold(q))
	blk_set_queue_congested(q, READ);
	else if (rl->count[READ] < queue_congestion_off_threshold(q))
	blk_clear_queue_congested(q, READ);

	if (rl->count[WRITE] >= queue_congestion_on_threshold(q))
	blk_set_queue_congested(q, WRITE);
	else if (rl->count[WRITE] < queue_congestion_off_threshold(q))
	blk_clear_queue_congested(q, WRITE);

	if (rl->count[READ] >= q->nr_requests) {
	blk_set_queue_full(q, READ);
	} else if (rl->count[READ]+1 <= q->nr_requests) {
	blk_clear_queue_full(q, READ);
	wake_up(&rl->wait[READ]);
	}

	if (rl->count[WRITE] >= q->nr_requests) {
	blk_set_queue_full(q, WRITE);
	} else if (rl->count[WRITE]+1 <= q->nr_requests) {
	blk_clear_queue_full(q, WRITE);
	wake_up(&rl->wait[WRITE]);
	}
	spin_unlock_irq(q->queue_lock);
	return ret;
	}

	static ssize_t queue_ra_show(struct request_queue q, char page)
	{
	int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);

	return queue_var_show(ra_kb, (page));
	}

	static ssize_t
	queue_ra_store(struct request_queue q, const char page, size_t count)
	{
	unsigned long ra_kb;
	ssize_t ret = queue_var_store(&ra_kb, page, count);

	q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);

	return ret;
	}

	static ssize_t queue_max_sectors_show(struct request_queue q, char page)
	{
	int max_sectors_kb = q->max_sectors >> 1;

	return queue_var_show(max_sectors_kb, (page));
	}

	static ssize_t queue_hw_sector_size_show(struct request_queue q, char page)
	{
	return queue_var_show(q->hardsect_size, page);
	}

	static ssize_t
	queue_max_sectors_store(struct request_queue q, const char page, size_t count)
	{
	unsigned long max_sectors_kb,
	max_hw_sectors_kb = q->max_hw_sectors >> 1,
	page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
	ssize_t ret = queue_var_store(&max_sectors_kb, page, count);

	if (max_sectors_kb > max_hw_sectors_kb \|\| max_sectors_kb < page_kb)
	return -EINVAL;

	spin_lock_irq(q->queue_lock);
	q->max_sectors = max_sectors_kb << 1;
	spin_unlock_irq(q->queue_lock);

	return ret;
	}

	static ssize_t queue_max_hw_sectors_show(struct request_queue q, char page)
	{
	int max_hw_sectors_kb = q->max_hw_sectors >> 1;

	return queue_var_show(max_hw_sectors_kb, (page));
	}

	static ssize_t queue_nonrot_show(struct request_queue q, char page)
	{
	return queue_var_show(!blk_queue_nonrot(q), page);
	}

	static ssize_t queue_nonrot_store(struct request_queue q, const char page,
	size_t count)
	{
	unsigned long nm;
	ssize_t ret = queue_var_store(&nm, page, count);

	spin_lock_irq(q->queue_lock);
	if (nm)
	queue_flag_clear(QUEUE_FLAG_NONROT, q);
	else
	queue_flag_set(QUEUE_FLAG_NONROT, q);
	spin_unlock_irq(q->queue_lock);

	return ret;
	}

	static ssize_t queue_nomerges_show(struct request_queue q, char page)
	{
	return queue_var_show(blk_queue_nomerges(q), page);
	}

	static ssize_t queue_nomerges_store(struct request_queue q, const char page,
	size_t count)
	{
	unsigned long nm;
	ssize_t ret = queue_var_store(&nm, page, count);

	spin_lock_irq(q->queue_lock);
	if (nm)
	queue_flag_set(QUEUE_FLAG_NOMERGES, q);
	else
	queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
	spin_unlock_irq(q->queue_lock);

	return ret;
	}

	static ssize_t queue_rq_affinity_show(struct request_queue q, char page)
	{
	unsigned int set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);

	return queue_var_show(set != 0, page);
	}

	static ssize_t
	queue_rq_affinity_store(struct request_queue q, const char page, size_t count)
	{
	ssize_t ret = -EINVAL;
	#if defined(CONFIG_USE_GENERIC_SMP_HELPERS)
	unsigned long val;

	ret = queue_var_store(&val, page, count);
	spin_lock_irq(q->queue_lock);
	if (val)
	queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
	else
	queue_flag_clear(QUEUE_FLAG_SAME_COMP, q);
	spin_unlock_irq(q->queue_lock);
	#endif
	return ret;
	}

	static struct queue_sysfs_entry queue_requests_entry = {
	.attr = {.name = "nr_requests", .mode = S_IRUGO \| S_IWUSR },
	.show = queue_requests_show,
	.store = queue_requests_store,
	};

	static struct queue_sysfs_entry queue_ra_entry = {
	.attr = {.name = "read_ahead_kb", .mode = S_IRUGO \| S_IWUSR },
	.show = queue_ra_show,
	.store = queue_ra_store,
	};

	static struct queue_sysfs_entry queue_max_sectors_entry = {
	.attr = {.name = "max_sectors_kb", .mode = S_IRUGO \| S_IWUSR },
	.show = queue_max_sectors_show,
	.store = queue_max_sectors_store,
	};

	static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
	.attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
	.show = queue_max_hw_sectors_show,
	};

	static struct queue_sysfs_entry queue_iosched_entry = {
	.attr = {.name = "scheduler", .mode = S_IRUGO \| S_IWUSR },
	.show = elv_iosched_show,
	.store = elv_iosched_store,
	};

	static struct queue_sysfs_entry queue_hw_sector_size_entry = {
	.attr = {.name = "hw_sector_size", .mode = S_IRUGO },
	.show = queue_hw_sector_size_show,
	};

	static struct queue_sysfs_entry queue_nonrot_entry = {
	.attr = {.name = "rotational", .mode = S_IRUGO \| S_IWUSR },
	.show = queue_nonrot_show,
	.store = queue_nonrot_store,
	};

	static struct queue_sysfs_entry queue_nomerges_entry = {
	.attr = {.name = "nomerges", .mode = S_IRUGO \| S_IWUSR },
	.show = queue_nomerges_show,
	.store = queue_nomerges_store,
	};

	static struct queue_sysfs_entry queue_rq_affinity_entry = {
	.attr = {.name = "rq_affinity", .mode = S_IRUGO \| S_IWUSR },
	.show = queue_rq_affinity_show,
	.store = queue_rq_affinity_store,
	};

	static struct attribute *default_attrs[] = {
	&queue_requests_entry.attr,
	&queue_ra_entry.attr,
	&queue_max_hw_sectors_entry.attr,
	&queue_max_sectors_entry.attr,
	&queue_iosched_entry.attr,
	&queue_hw_sector_size_entry.attr,
	&queue_nonrot_entry.attr,
	&queue_nomerges_entry.attr,
	&queue_rq_affinity_entry.attr,
	NULL,
	};

	#define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)

	static ssize_t
	queue_attr_show(struct kobject kobj, struct attribute attr, char *page)
	{
	struct queue_sysfs_entry *entry = to_queue(attr);
	struct request_queue *q =
	container_of(kobj, struct request_queue, kobj);
	ssize_t res;

	if (!entry->show)
	return -EIO;
	mutex_lock(&q->sysfs_lock);
	if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
	mutex_unlock(&q->sysfs_lock);
	return -ENOENT;
	}
	res = entry->show(q, page);
	mutex_unlock(&q->sysfs_lock);
	return res;
	}

	static ssize_t
	queue_attr_store(struct kobject kobj, struct attribute attr,
	const char *page, size_t length)
	{
	struct queue_sysfs_entry *entry = to_queue(attr);
	struct request_queue *q;
	ssize_t res;

	if (!entry->store)
	return -EIO;

	q = container_of(kobj, struct request_queue, kobj);
	mutex_lock(&q->sysfs_lock);
	if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
	mutex_unlock(&q->sysfs_lock);
	return -ENOENT;
	}
	res = entry->store(q, page, length);
	mutex_unlock(&q->sysfs_lock);
	return res;
	}

	/**
	* blk_cleanup_queue: - release a &struct request_queue when it is no longer needed
	* @kobj: the kobj belonging of the request queue to be released
	*
	* Description:
	* blk_cleanup_queue is the pair to blk_init_queue() or
	* blk_queue_make_request(). It should be called when a request queue is
	* being released; typically when a block device is being de-registered.
	* Currently, its primary task it to free all the &struct request
	* structures that were allocated to the queue and the queue itself.
	*
	* Caveat:
	* Hopefully the low level driver will have finished any
	* outstanding requests first...
	**/
	static void blk_release_queue(struct kobject *kobj)
	{
	struct request_queue *q =
	container_of(kobj, struct request_queue, kobj);
	struct request_list *rl = &q->rq;

	blk_sync_queue(q);

	if (rl->rq_pool)
	mempool_destroy(rl->rq_pool);

	if (q->queue_tags)
	__blk_queue_free_tags(q);

	blk_trace_shutdown(q);

	bdi_destroy(&q->backing_dev_info);
	kmem_cache_free(blk_requestq_cachep, q);
	}

	static struct sysfs_ops queue_sysfs_ops = {
	.show = queue_attr_show,
	.store = queue_attr_store,
	};

	struct kobj_type blk_queue_ktype = {
	.sysfs_ops = &queue_sysfs_ops,
	.default_attrs = default_attrs,
	.release = blk_release_queue,
	};

	int blk_register_queue(struct gendisk *disk)
	{
	int ret;

	struct request_queue *q = disk->queue;

	if (WARN_ON(!q))
	return -ENXIO;

	if (!q->request_fn)
	return 0;

	ret = kobject_add(&q->kobj, kobject_get(&disk_to_dev(disk)->kobj),
	"%s", "queue");
	if (ret < 0)
	return ret;

	kobject_uevent(&q->kobj, KOBJ_ADD);

	ret = elv_register_queue(q);
	if (ret) {
	kobject_uevent(&q->kobj, KOBJ_REMOVE);
	kobject_del(&q->kobj);
	return ret;
	}

	return 0;
	}

	void blk_unregister_queue(struct gendisk *disk)
	{
	struct request_queue *q = disk->queue;

	if (WARN_ON(!q))
	return;

	if (q->request_fn) {
	elv_unregister_queue(q);

	kobject_uevent(&q->kobj, KOBJ_REMOVE);
	kobject_del(&q->kobj);
	kobject_put(&disk_to_dev(disk)->kobj);
	}
	}