// SPDX-License-Identifier: GPL-2.0
#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 "blk.h"
#include "blk-mq.h"

static void blk_mq_sysfs_release(struct kobject *kobj)
{
        struct blk_mq_ctxs *ctxs = container_of(kobj, struct blk_mq_ctxs, kobj);

        free_percpu(ctxs->queue_ctx);
        kfree(ctxs);
}

static void blk_mq_ctx_sysfs_release(struct kobject *kobj)
{
        struct blk_mq_ctx *ctx = container_of(kobj, struct blk_mq_ctx, kobj);

        /* ctx->ctxs won't be released until all ctx are freed */
        kobject_put(&ctx->ctxs->kobj);
}

static void blk_mq_hw_sysfs_release(struct kobject *kobj)
{
        struct blk_mq_hw_ctx *hctx = container_of(kobj, struct blk_mq_hw_ctx,
                                                  kobj);

        sbitmap_free(&hctx->ctx_map);
        free_cpumask_var(hctx->cpumask);
        kfree(hctx->ctxs);
        kfree(hctx);
}

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

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;

        mutex_lock(&q->elevator_lock);
        res = entry->show(hctx, page);
        mutex_unlock(&q->elevator_lock);
        return res;
}

static ssize_t blk_mq_hw_sysfs_nr_tags_show(struct blk_mq_hw_ctx *hctx,
                                            char *page)
{
        return sprintf(page, "%u\n", hctx->tags->nr_tags);
}

static ssize_t blk_mq_hw_sysfs_nr_reserved_tags_show(struct blk_mq_hw_ctx *hctx,
                                                     char *page)
{
        return sprintf(page, "%u\n", hctx->tags->nr_reserved_tags);
}

static ssize_t blk_mq_hw_sysfs_cpus_show(struct blk_mq_hw_ctx *hctx, char *page)
{
        const size_t size = PAGE_SIZE - 1;
        unsigned int i, first = 1;
        int ret = 0, pos = 0;

        for_each_cpu(i, hctx->cpumask) {
                if (first)
                        ret = snprintf(pos + page, size - pos, "%u", i);
                else
                        ret = snprintf(pos + page, size - pos, ", %u", i);

                if (ret >= size - pos)
                        break;

                first = 0;
                pos += ret;
        }

        ret = snprintf(pos + page, size + 1 - pos, "\n");
        return pos + ret;
}

static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_nr_tags = {
        .attr = {.name = "nr_tags", .mode = 0444 },
        .show = blk_mq_hw_sysfs_nr_tags_show,
};
static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_nr_reserved_tags = {
        .attr = {.name = "nr_reserved_tags", .mode = 0444 },
        .show = blk_mq_hw_sysfs_nr_reserved_tags_show,
};
static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_cpus = {
        .attr = {.name = "cpu_list", .mode = 0444 },
        .show = blk_mq_hw_sysfs_cpus_show,
};

static struct attribute *default_hw_ctx_attrs[] = {
        &blk_mq_hw_sysfs_nr_tags.attr,
        &blk_mq_hw_sysfs_nr_reserved_tags.attr,
        &blk_mq_hw_sysfs_cpus.attr,
        NULL,
};
ATTRIBUTE_GROUPS(default_hw_ctx);

static const struct sysfs_ops blk_mq_hw_sysfs_ops = {
        .show   = blk_mq_hw_sysfs_show,
};

static const struct kobj_type blk_mq_ktype = {
        .release        = blk_mq_sysfs_release,
};

static const struct kobj_type blk_mq_ctx_ktype = {
        .release        = blk_mq_ctx_sysfs_release,
};

static const struct kobj_type blk_mq_hw_ktype = {
        .sysfs_ops      = &blk_mq_hw_sysfs_ops,
        .default_groups = default_hw_ctx_groups,
        .release        = blk_mq_hw_sysfs_release,
};

static void blk_mq_unregister_hctx(struct blk_mq_hw_ctx *hctx)
{
        struct blk_mq_ctx *ctx;
        int i;

        if (!hctx->nr_ctx)
                return;

        hctx_for_each_ctx(hctx, ctx, i)
                if (ctx->kobj.state_in_sysfs)
                        kobject_del(&ctx->kobj);

        if (hctx->kobj.state_in_sysfs)
                kobject_del(&hctx->kobj);
}

static int blk_mq_register_hctx(struct blk_mq_hw_ctx *hctx)
{
        struct request_queue *q = hctx->queue;
        struct blk_mq_ctx *ctx;
        int i, j, ret;

        if (!hctx->nr_ctx)
                return 0;

        ret = kobject_add(&hctx->kobj, q->mq_kobj, "%u", hctx->queue_num);
        if (ret)
                return ret;

        hctx_for_each_ctx(hctx, ctx, i) {
                ret = kobject_add(&ctx->kobj, &hctx->kobj, "cpu%u", ctx->cpu);
                if (ret)
                        goto out;
        }

        return 0;
out:
        hctx_for_each_ctx(hctx, ctx, j) {
                if (j < i)
                        kobject_del(&ctx->kobj);
        }
        kobject_del(&hctx->kobj);
        return ret;
}

void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx)
{
        kobject_init(&hctx->kobj, &blk_mq_hw_ktype);
}

void blk_mq_sysfs_deinit(struct request_queue *q)
{
        struct blk_mq_ctx *ctx;
        int cpu;

        for_each_possible_cpu(cpu) {
                ctx = per_cpu_ptr(q->queue_ctx, cpu);
                kobject_put(&ctx->kobj);
        }
        kobject_put(q->mq_kobj);
}

void blk_mq_sysfs_init(struct request_queue *q)
{
        struct blk_mq_ctx *ctx;
        int cpu;

        kobject_init(q->mq_kobj, &blk_mq_ktype);

        for_each_possible_cpu(cpu) {
                ctx = per_cpu_ptr(q->queue_ctx, cpu);

                kobject_get(q->mq_kobj);
                kobject_init(&ctx->kobj, &blk_mq_ctx_ktype);
        }
}

int blk_mq_sysfs_register(struct gendisk *disk)
{
        struct request_queue *q = disk->queue;
        struct blk_mq_hw_ctx *hctx;
        unsigned long i, j;
        int ret;

        ret = kobject_add(q->mq_kobj, &disk_to_dev(disk)->kobj, "mq");
        if (ret < 0)
                return ret;

        kobject_uevent(q->mq_kobj, KOBJ_ADD);

        mutex_lock(&q->tag_set->tag_list_lock);
        queue_for_each_hw_ctx(q, hctx, i) {
                ret = blk_mq_register_hctx(hctx);
                if (ret)
                        goto out_unreg;
        }
        mutex_unlock(&q->tag_set->tag_list_lock);
        return 0;

out_unreg:
        queue_for_each_hw_ctx(q, hctx, j) {
                if (j < i)
                        blk_mq_unregister_hctx(hctx);
        }
        mutex_unlock(&q->tag_set->tag_list_lock);

        kobject_uevent(q->mq_kobj, KOBJ_REMOVE);
        kobject_del(q->mq_kobj);
        return ret;
}

void blk_mq_sysfs_unregister(struct gendisk *disk)
{
        struct request_queue *q = disk->queue;
        struct blk_mq_hw_ctx *hctx;
        unsigned long i;

        mutex_lock(&q->tag_set->tag_list_lock);
        queue_for_each_hw_ctx(q, hctx, i)
                blk_mq_unregister_hctx(hctx);
        mutex_unlock(&q->tag_set->tag_list_lock);

        kobject_uevent(q->mq_kobj, KOBJ_REMOVE);
        kobject_del(q->mq_kobj);
}

void blk_mq_sysfs_unregister_hctxs(struct request_queue *q)
{
        struct blk_mq_hw_ctx *hctx;
        unsigned long i;

        if (!blk_queue_registered(q))
                return;

        queue_for_each_hw_ctx(q, hctx, i)
                blk_mq_unregister_hctx(hctx);
}

int blk_mq_sysfs_register_hctxs(struct request_queue *q)
{
        struct blk_mq_hw_ctx *hctx;
        unsigned long i;
        int ret = 0;

        if (!blk_queue_registered(q))
                goto out;

        queue_for_each_hw_ctx(q, hctx, i) {
                ret = blk_mq_register_hctx(hctx);
                if (ret)
                        break;
        }

out:
        return ret;
}