/*
   * Functions related to sysfs handling
   */
  #include <linux/kernel.h>

  #include <linux/slab.h>

  #include <linux/module.h>
  #include <linux/bio.h>
  #include <linux/blkdev.h>
  #include <linux/blktrace_api.h>

  #include <linux/blk-mq.h>

  
  #include "blk.h"

  #include "blk-cgroup.h"

  #include "blk-mq.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 long var, char *page)

  {

  	return sprintf(page, "%lu
  ", var);

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

  	int err;
  	unsigned long v;

  	err = kstrtoul(page, 10, &v);

  	if (err || v > UINT_MAX)
  		return -EINVAL;
  
  	*var = v;

  	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)
  {

  	unsigned long nr;

  	int ret, err;

  	if (!q->request_fn && !q->mq_ops)

  		return -EINVAL;
  
  	ret = queue_var_store(&nr, page, count);

  	if (ret < 0)
  		return ret;

  	if (nr < BLKDEV_MIN_RQ)
  		nr = BLKDEV_MIN_RQ;

  	if (q->request_fn)
  		err = blk_update_nr_requests(q, nr);
  	else
  		err = blk_mq_update_nr_requests(q, nr);
  
  	if (err)
  		return err;

  	return ret;
  }
  
  static ssize_t queue_ra_show(struct request_queue *q, char *page)
  {

  	unsigned long 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);

  	if (ret < 0)
  		return ret;

  	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 = queue_max_sectors(q) >> 1;

  
  	return queue_var_show(max_sectors_kb, (page));
  }

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

  static ssize_t queue_max_integrity_segments_show(struct request_queue *q, char *page)
  {
  	return queue_var_show(q->limits.max_integrity_segments, (page));
  }

  static ssize_t queue_max_segment_size_show(struct request_queue *q, char *page)
  {

  	if (blk_queue_cluster(q))

  		return queue_var_show(queue_max_segment_size(q), (page));
  
  	return queue_var_show(PAGE_CACHE_SIZE, (page));
  }

  static ssize_t queue_logical_block_size_show(struct request_queue *q, char *page)

  {

  	return queue_var_show(queue_logical_block_size(q), page);

  }

  static ssize_t queue_physical_block_size_show(struct request_queue *q, char *page)
  {
  	return queue_var_show(queue_physical_block_size(q), page);
  }
  
  static ssize_t queue_io_min_show(struct request_queue *q, char *page)
  {
  	return queue_var_show(queue_io_min(q), page);
  }
  
  static ssize_t queue_io_opt_show(struct request_queue *q, char *page)
  {
  	return queue_var_show(queue_io_opt(q), page);

  }

  static ssize_t queue_discard_granularity_show(struct request_queue *q, char *page)
  {
  	return queue_var_show(q->limits.discard_granularity, page);
  }
  
  static ssize_t queue_discard_max_show(struct request_queue *q, char *page)
  {

  	return sprintf(page, "%llu
  ",
  		       (unsigned long long)q->limits.max_discard_sectors << 9);

  }

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

  static ssize_t queue_write_same_max_show(struct request_queue *q, char *page)
  {
  	return sprintf(page, "%llu
  ",
  		(unsigned long long)q->limits.max_write_same_sectors << 9);
  }

  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 = queue_max_hw_sectors(q) >> 1,

  			page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
  	ssize_t ret = queue_var_store(&max_sectors_kb, page, count);

  	if (ret < 0)
  		return ret;

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

  	spin_lock_irq(q->queue_lock);

  	q->limits.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 = queue_max_hw_sectors(q) >> 1;

  
  	return queue_var_show(max_hw_sectors_kb, (page));
  }

  #define QUEUE_SYSFS_BIT_FNS(name, flag, neg)				\
  static ssize_t								\
  queue_show_##name(struct request_queue *q, char *page)			\
  {									\
  	int bit;							\
  	bit = test_bit(QUEUE_FLAG_##flag, &q->queue_flags);		\
  	return queue_var_show(neg ? !bit : bit, page);			\
  }									\
  static ssize_t								\
  queue_store_##name(struct request_queue *q, const char *page, size_t count) \
  {									\
  	unsigned long val;						\
  	ssize_t ret;							\
  	ret = queue_var_store(&val, page, count);			\

  	if (ret < 0)							\
  		 return ret;						\

  	if (neg)							\
  		val = !val;						\
  									\
  	spin_lock_irq(q->queue_lock);					\
  	if (val)							\
  		queue_flag_set(QUEUE_FLAG_##flag, q);			\
  	else								\
  		queue_flag_clear(QUEUE_FLAG_##flag, q);			\
  	spin_unlock_irq(q->queue_lock);					\
  	return ret;							\

  }

  QUEUE_SYSFS_BIT_FNS(nonrot, NONROT, 1);
  QUEUE_SYSFS_BIT_FNS(random, ADD_RANDOM, 0);
  QUEUE_SYSFS_BIT_FNS(iostats, IO_STAT, 0);
  #undef QUEUE_SYSFS_BIT_FNS

  static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
  {

  	return queue_var_show((blk_queue_nomerges(q) << 1) |
  			       blk_queue_noxmerges(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);

  	if (ret < 0)
  		return ret;

  	spin_lock_irq(q->queue_lock);

  	queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
  	queue_flag_clear(QUEUE_FLAG_NOXMERGES, q);
  	if (nm == 2)

  		queue_flag_set(QUEUE_FLAG_NOMERGES, q);

  	else if (nm)
  		queue_flag_set(QUEUE_FLAG_NOXMERGES, q);

  	spin_unlock_irq(q->queue_lock);

  	return ret;
  }

  static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page)
  {

  	bool set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);

  	bool force = test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags);

  	return queue_var_show(set << force, page);

  }
  
  static ssize_t
  queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
  {
  	ssize_t ret = -EINVAL;

  #ifdef CONFIG_SMP

  	unsigned long val;
  
  	ret = queue_var_store(&val, page, count);

  	if (ret < 0)
  		return ret;

  	spin_lock_irq(q->queue_lock);

  	if (val == 2) {

  		queue_flag_set(QUEUE_FLAG_SAME_COMP, q);

  		queue_flag_set(QUEUE_FLAG_SAME_FORCE, q);
  	} else if (val == 1) {
  		queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
  		queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
  	} else if (val == 0) {

  		queue_flag_clear(QUEUE_FLAG_SAME_COMP, q);
  		queue_flag_clear(QUEUE_FLAG_SAME_FORCE, 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_max_segments_entry = {
  	.attr = {.name = "max_segments", .mode = S_IRUGO },
  	.show = queue_max_segments_show,
  };

  static struct queue_sysfs_entry queue_max_integrity_segments_entry = {
  	.attr = {.name = "max_integrity_segments", .mode = S_IRUGO },
  	.show = queue_max_integrity_segments_show,
  };

  static struct queue_sysfs_entry queue_max_segment_size_entry = {
  	.attr = {.name = "max_segment_size", .mode = S_IRUGO },
  	.show = queue_max_segment_size_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_logical_block_size_show,
  };
  
  static struct queue_sysfs_entry queue_logical_block_size_entry = {
  	.attr = {.name = "logical_block_size", .mode = S_IRUGO },
  	.show = queue_logical_block_size_show,

  };

  static struct queue_sysfs_entry queue_physical_block_size_entry = {
  	.attr = {.name = "physical_block_size", .mode = S_IRUGO },
  	.show = queue_physical_block_size_show,
  };
  
  static struct queue_sysfs_entry queue_io_min_entry = {
  	.attr = {.name = "minimum_io_size", .mode = S_IRUGO },
  	.show = queue_io_min_show,
  };
  
  static struct queue_sysfs_entry queue_io_opt_entry = {
  	.attr = {.name = "optimal_io_size", .mode = S_IRUGO },
  	.show = queue_io_opt_show,

  };

  static struct queue_sysfs_entry queue_discard_granularity_entry = {
  	.attr = {.name = "discard_granularity", .mode = S_IRUGO },
  	.show = queue_discard_granularity_show,
  };
  
  static struct queue_sysfs_entry queue_discard_max_entry = {
  	.attr = {.name = "discard_max_bytes", .mode = S_IRUGO },
  	.show = queue_discard_max_show,
  };

  static struct queue_sysfs_entry queue_discard_zeroes_data_entry = {
  	.attr = {.name = "discard_zeroes_data", .mode = S_IRUGO },
  	.show = queue_discard_zeroes_data_show,
  };

  static struct queue_sysfs_entry queue_write_same_max_entry = {
  	.attr = {.name = "write_same_max_bytes", .mode = S_IRUGO },
  	.show = queue_write_same_max_show,
  };

  static struct queue_sysfs_entry queue_nonrot_entry = {
  	.attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR },

  	.show = queue_show_nonrot,
  	.store = queue_store_nonrot,

  };

  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 queue_sysfs_entry queue_iostats_entry = {
  	.attr = {.name = "iostats", .mode = S_IRUGO | S_IWUSR },

  	.show = queue_show_iostats,
  	.store = queue_store_iostats,

  };

  static struct queue_sysfs_entry queue_random_entry = {
  	.attr = {.name = "add_random", .mode = S_IRUGO | S_IWUSR },

  	.show = queue_show_random,
  	.store = queue_store_random,

  };

  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_max_segments_entry.attr,

  	&queue_max_integrity_segments_entry.attr,

  	&queue_max_segment_size_entry.attr,

  	&queue_iosched_entry.attr,

  	&queue_hw_sector_size_entry.attr,

  	&queue_logical_block_size_entry.attr,

  	&queue_physical_block_size_entry.attr,
  	&queue_io_min_entry.attr,
  	&queue_io_opt_entry.attr,

  	&queue_discard_granularity_entry.attr,
  	&queue_discard_max_entry.attr,

  	&queue_discard_zeroes_data_entry.attr,

  	&queue_write_same_max_entry.attr,

  	&queue_nonrot_entry.attr,

  	&queue_nomerges_entry.attr,

  	&queue_rq_affinity_entry.attr,

  	&queue_iostats_entry.attr,

  	&queue_random_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 (blk_queue_dying(q)) {

  		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 (blk_queue_dying(q)) {

  		mutex_unlock(&q->sysfs_lock);
  		return -ENOENT;
  	}
  	res = entry->store(q, page, length);
  	mutex_unlock(&q->sysfs_lock);
  	return res;
  }

  static void blk_free_queue_rcu(struct rcu_head *rcu_head)
  {
  	struct request_queue *q = container_of(rcu_head, struct request_queue,
  					       rcu_head);
  	kmem_cache_free(blk_requestq_cachep, q);
  }

  /**

   * blk_release_queue: - release a &struct request_queue when it is no longer needed
   * @kobj:    the kobj belonging to the request queue to be released

   *
   * Description:

   *     blk_release_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.
   *

   * Note:
   *     The low level driver must have finished any outstanding requests first
   *     via blk_cleanup_queue().

   **/
  static void blk_release_queue(struct kobject *kobj)
  {
  	struct request_queue *q =
  		container_of(kobj, struct request_queue, kobj);

  	blkcg_exit_queue(q);

  	if (q->elevator) {
  		spin_lock_irq(q->queue_lock);
  		ioc_clear_queue(q);
  		spin_unlock_irq(q->queue_lock);

  		elevator_exit(q->elevator);

  	}

  	blk_exit_rl(&q->root_rl);

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

  	if (!q->mq_ops)

  		blk_free_flush_queue(q->fq);

  	else
  		blk_mq_release(q);

  	blk_trace_shutdown(q);

  	ida_simple_remove(&blk_queue_ida, q->id);

  	call_rcu(&q->rcu_head, blk_free_queue_rcu);

  }

  static const 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 device *dev = disk_to_dev(disk);

  	struct request_queue *q = disk->queue;

  	if (WARN_ON(!q))

  		return -ENXIO;

  	/*

  	 * SCSI probing may synchronously create and destroy a lot of
  	 * request_queues for non-existent devices.  Shutting down a fully
  	 * functional queue takes measureable wallclock time as RCU grace
  	 * periods are involved.  To avoid excessive latency in these
  	 * cases, a request_queue starts out in a degraded mode which is
  	 * faster to shut down and is made fully functional here as
  	 * request_queues for non-existent devices never get registered.

  	 */

  	if (!blk_queue_init_done(q)) {
  		queue_flag_set_unlocked(QUEUE_FLAG_INIT_DONE, q);
  		blk_queue_bypass_end(q);

  		if (q->mq_ops)
  			blk_mq_finish_init(q);

  	}

  	ret = blk_trace_init_sysfs(dev);
  	if (ret)
  		return ret;

  	ret = kobject_add(&q->kobj, kobject_get(&dev->kobj), "%s", "queue");

  	if (ret < 0) {
  		blk_trace_remove_sysfs(dev);

  		return ret;

  	}

  
  	kobject_uevent(&q->kobj, KOBJ_ADD);

  	if (q->mq_ops)
  		blk_mq_register_disk(disk);

  	if (!q->request_fn)
  		return 0;

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

  		blk_trace_remove_sysfs(dev);

  		kobject_put(&dev->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->mq_ops)
  		blk_mq_unregister_disk(disk);

  	if (q->request_fn)

  		elv_unregister_queue(q);

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

  }