/*
 * 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 "blk.h"
#include "blk-cgroup.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\n", var);
}

static ssize_t
queue_var_store(unsigned long *var, const char *page, size_t count)
{
	int err;
	unsigned long v;

	err = strict_strtoul(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)
{
	struct request_list *rl;
	unsigned long nr;
	int ret;

	if (!q->request_fn)
		return -EINVAL;

	ret = queue_var_store(&nr, page, count);
	if (ret < 0)
		return ret;

	if (nr < BLKDEV_MIN_RQ)
		nr = BLKDEV_MIN_RQ;

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

	/* congestion isn't cgroup aware and follows root blkcg for now */
	rl = &q->root_rl;

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

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

	blk_queue_for_each_rl(rl, q) {
		if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
			blk_set_rl_full(rl, BLK_RW_SYNC);
		} else {
			blk_clear_rl_full(rl, BLK_RW_SYNC);
			wake_up(&rl->wait[BLK_RW_SYNC]);
		}

		if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
			blk_set_rl_full(rl, BLK_RW_ASYNC);
		} else {
			blk_clear_rl_full(rl, BLK_RW_ASYNC);
			wake_up(&rl->wait[BLK_RW_ASYNC]);
		}
	}

	spin_unlock_irq(q->queue_lock);
	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\n",
		       (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\n",
		(unsigned long long)q->limits.max_write_same_sectors << 9);