#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/backing-dev.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/smp.h>

#include <linux/blk-mq.h>
#include "blk-mq.h"
#include "blk-mq-tag.h"

static void blk_mq_sysfs_release(struct kobject *kobj)
{
}

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

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

static ssize_t blk_mq_sysfs_show(struct kobject *kobj, struct attribute *attr,
				 char *page)
{
	struct blk_mq_ctx_sysfs_entry *entry;
	struct blk_mq_ctx *ctx;
	struct request_queue *q;
	ssize_t res;

	entry = container_of(attr, struct blk_mq_ctx_sysfs_entry, attr);
	ctx = container_of(kobj, struct blk_mq_ctx, kobj);
	q = ctx->queue;

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

	res = -ENOENT;
	mutex_lock(&q->sysfs_lock);
	if (!blk_queue_dying(q))
		res = entry->show(ctx, page);
	mutex_unlock(&q->sysfs_lock);
	return res;
}

static ssize_t blk_mq_sysfs_store(struct kobject *kobj, struct attribute *attr,
				  const char *page, size_t length)
{
	struct blk_mq_ctx_sysfs_entry *entry;
	struct blk_mq_ctx *ctx;
	struct request_queue *q;
	ssize_t res;

	entry = container_of(attr, struct blk_mq_ctx_sysfs_entry, attr);
	ctx = container_of(kobj, struct blk_mq_ctx, kobj);
	q = ctx->queue;

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

	res = -ENOENT;
	mutex_lock(&q->sysfs_lock);
	if (!blk_queue_dying(q))
		res = entry->store(ctx, page, length);
	mutex_unlock(&q->sysfs_lock);
	return res;
}

static ssize_t blk_mq_hw_sysfs_show(struct kobject *kobj,
				    struct attribute *attr, char *page)
{
	struct blk_mq_hw_ctx_sysfs_entry *entry;
	struct blk_mq_hw_ctx *hctx;
	struct request_queue *q;
	ssize_t res;

	entry = container_of(attr, struct blk_mq_hw_ctx_sysfs_entry, attr);
	hctx = container_of(kobj, struct blk_mq_hw_ctx, kobj);
	q = hctx->queue;

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

	res = -ENOENT;
	mutex_lock(&q->sysfs_lock);
	if (!blk_queue_dying(q))
		res = entry->show(hctx, page);
	mutex_unlock(&q->sysfs_lock);
	return res;
}

static ssize_t blk_mq_hw_sysfs_store(struct kobject *kobj,
				     struct attribute *attr, const char *page,
				     size_t length)
{
	struct blk_mq_hw_ctx_sysfs_entry *entry;
	struct blk_mq_hw_ctx *hctx;
	struct request_queue *q;
	ssize_t res;

	entry = container_of(attr, struct blk_mq_hw_ctx_sysfs_entry, attr);
	hctx = container_of(kobj, struct blk_mq_hw_ctx, kobj);
	q = hctx->queue;

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

	res = -ENOENT;
	mutex_lock(&q->sysfs_lock);
	if (!blk_queue_dying(q))
		res = entry->store(hctx, page, length);
	mutex_unlock(&q->sysfs_lock);
	return res;
}

static ssize_t blk_mq_sysfs_dispatched_show(struct blk_mq_ctx *ctx, char *page)
{
	return sprintf(page, "%lu %lu\n", ctx->rq_dispatched[1],
				ctx->rq_dispatched[0]);
}

static ssize_t blk_mq_sysfs_merged_show(struct blk_mq_ctx *ctx, char *page)
{
	return sprintf(page, "%lu\n", ctx->rq_merged);
}

static ssize_t blk_mq_sysfs_completed_show(struct blk_mq_ctx *ctx, char *page)
{
	return sprintf(page, "%lu %lu\n", ctx->rq_completed[1],
				ctx->rq_completed[0]);
}

static ssize_t sysfs_list_show(char *page, struct list_head *list, char *msg)
{
	char *start_page = page;
	struct request *rq;

	page += sprintf(page, "%s:\n", msg);

	list_for_each_entry(rq, list, queuelist)
		page += sprintf(page, "\t%p\n", rq);

	return page - start_page;
}

static ssize_t blk_mq_sysfs_rq_list_show(struct blk_mq_ctx *ctx, char *page)
{
	ssize_t ret;

	spin_lock(&ctx->lock);
	ret = sysfs_list_show(page, &ctx->rq_list, "CTX pending");
	spin_unlock(&ctx->lock);

	return ret;
}

static ssize_t blk_mq_hw_sysfs_queued_show(struct blk_mq_hw_ctx *hctx,
					   char *page)
{
	return sprintf(page, "%lu\n", hctx->queued);
}

static ssize_t blk_mq_hw_sysfs_run_show(struct blk_mq_hw_ctx *hctx, char *page)
{
	return sprintf(page, "%lu\n", hctx->run);
}

static ssize_t blk_mq_hw_sysfs_dispatched_show(struct blk_mq_hw_ctx *hctx,
					       char *page)
{
	char *start_page = page;
	int i;

	page += sprintf(page, "%8u\t%lu\n", 0U, hctx->dispatched[0]);

	for (i = 1; i < BLK_MQ_MAX_DISPATCH_ORDER; i++) {
		unsigned long d = 1U << (i - 1);

		page += sprintf(page, "%8lu\t%lu\n", d, hctx->dispatched[i]);
	}

	return page - start_page;
}

static ssize_t blk_mq_hw_sysfs_rq_list_show(struct blk_mq_hw_ctx *hctx,
					    char *page)
{
	ssize_t ret;

	spin_lock(&hctx->lock);
	ret = sysfs_list_show(page, &hctx->dispatch, "HCTX pending");
	spin_unlock(&hctx->lock);

	return ret;
}

static ssize_t blk_mq_hw_sysfs_ipi_show(struct blk_mq_hw_ctx *hctx, char *page)
{
	ssize_t ret;

	spin_lock(&hctx->lock);
	ret = sprintf(page, "%u\n", !!(hctx->flags & BLK_MQ_F_SHOULD_IPI));
	spin_unlock(&hctx->lock);

	return ret;
}

static ssize_t blk_mq_hw_sysfs_ipi_store(struct blk_mq_hw_ctx *hctx,
					 const char *page, size_t len)
{
	struct blk_mq_ctx *ctx;
	unsigned long ret;
	unsigned int i;

	if (kstrtoul(page, 10, &ret)) {
		pr_err("blk-mq-sysfs: invalid input '%s'\n", page);
		return -EINVAL;
	}

	spin_lock(&hctx->lock);
	if (ret)
		hctx->flags |= BLK_MQ_F_SHOULD_IPI;
	else
		hctx->flags &= ~BLK_MQ_F_SHOULD_IPI;
	spin_unlock(&hctx->lock);