/*        $NetBSD: dm_target_delay.c,v 1.2 2020/01/21 16:27:53 tkusumi Exp $      */

/*
 * Copyright (c) 2020 The NetBSD Foundation, Inc.
 * Copyright (c) 2015 The DragonFly Project.  All rights reserved.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Tomohiro Kusumi <tkusumi@netbsd.org>.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: dm_target_delay.c,v 1.2 2020/01/21 16:27:53 tkusumi Exp $");

#include <sys/types.h>
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/buf.h>
#include <sys/kmem.h>
#include <sys/mutex.h>
#include <sys/queue.h>
#include <sys/callout.h>
#include <sys/pool.h>
#include <sys/kthread.h>

#include "dm.h"

struct dm_delay_buf {
        TAILQ_ENTRY(dm_delay_buf) entry;
        struct buf *bp;
        int expire;
};
TAILQ_HEAD(dm_delay_buf_list, dm_delay_buf);

struct dm_delay_info {
        dm_pdev_t *pdev;
        uint64_t offset;
        int delay;
        int count;
        int enabled;
        struct dm_delay_buf_list buf_list;
        struct callout cal;
        kmutex_t buf_mtx;
        kmutex_t cal_mtx;
        kmutex_t token; /* lwkt_token in DragonFly */
};

typedef struct target_delay_config {
        struct dm_delay_info read;
        struct dm_delay_info write;
        int argc; /* either 3 or 6 */
} dm_target_delay_config_t;

static int _init(struct dm_delay_info*, char**);
static int _table(struct dm_delay_info*, char*);
static void _strategy(struct dm_delay_info*, struct buf*);
static __inline void _submit(struct dm_delay_info*, struct buf*);
static void _destroy(struct dm_delay_info*);
static void _timeout(void*);
static void _thread(void*);
static __inline void _debug(struct dm_delay_info*, const char*);

static struct pool pool;
static bool pool_initialized = false;

#ifdef DM_TARGET_MODULE
/*
 * Every target can be compiled directly to dm driver or as a
 * separate module this part of target is used for loading targets
 * to dm driver.
 * Target can be unloaded from kernel only if there are no users of
 * it e.g. there are no devices which uses that target.
 */
#include <sys/kernel.h>
#include <sys/module.h>

MODULE(MODULE_CLASS_MISC, dm_target_delay, NULL);

static int
dm_target_delay_modcmd(modcmd_t cmd, void *arg)
{
        dm_target_t *dmt;
        int r;

        switch (cmd) {
        case MODULE_CMD_INIT:
                if ((dmt = dm_target_lookup("delay")) != NULL) {
                        dm_target_unbusy(dmt);
                        return EEXIST;
                }
                dmt = dm_target_alloc("delay");

                dmt->version[0] = 1;
                dmt->version[1] = 0;
                dmt->version[2] = 0;
                dmt->init = &dm_target_delay_init;
                dmt->table = &dm_target_delay_table;
                dmt->strategy = &dm_target_delay_strategy;
                dmt->sync = &dm_target_delay_sync;
                dmt->destroy = &dm_target_delay_destroy;
                //dmt->upcall = &dm_target_delay_upcall;
                dmt->secsize = &dm_target_delay_secsize;

                dm_target_delay_pool_create();
                r = dm_target_insert(dmt);

                break;

        case MODULE_CMD_FINI:
                r = dm_target_rem("delay");
                dm_target_delay_pool_destroy();
                break;

        case MODULE_CMD_STAT:
                return ENOTTY;

        default:
                return ENOTTY;
        }

        return r;
}
#endif

int
dm_target_delay_init(dm_table_entry_t *table_en, int argc, char **argv)
{
        dm_target_delay_config_t *tdc;
        int ret;

        if (argc != 3 && argc != 6) {
                printf("Delay target takes 3 or 6 args, %d given\n", argc);
                return EINVAL;
        }

        aprint_debug("Delay target init function called: argc=%d\n", argc);

        tdc = kmem_alloc(sizeof(dm_target_delay_config_t), KM_SLEEP);
        tdc->argc = argc;

        ret = _init(&tdc->read, argv);
        if (ret) {
                kmem_free(tdc, sizeof(*tdc));
                return ret;
        }

        if (argc == 6)
                argv += 3;

        ret = _init(&tdc->write, argv);
        if (ret) {
                dm_pdev_decr(tdc->read.pdev);
                kmem_free(tdc, sizeof(*tdc));
                return ret;
        }

        dm_table_add_deps(table_en, tdc->read.pdev);
        dm_table_add_deps(table_en, tdc->write.pdev);

        table_en->target_config = tdc;

        return 0;
}

static int
_init(struct dm_delay_info *di, char **argv)
{
        dm_pdev_t *dmp;
        int tmp;

        if (argv[0] == NULL)
                return EINVAL;
        if ((dmp = dm_pdev_insert(argv[0])) == NULL)
                return ENOENT;

        di->pdev = dmp;
        di->offset = atoi64(argv[1]);
        tmp = atoi64(argv[2]);
        di->delay = tmp * hz / 1000;
        di->count = 0;

        TAILQ_INIT(&di->buf_list);
        callout_init(&di->cal, 0);
        mutex_init(&di->buf_mtx, MUTEX_DEFAULT, IPL_NONE);
        mutex_init(&di->cal_mtx, MUTEX_DEFAULT, IPL_NONE);
        mutex_init(&di->token, MUTEX_DEFAULT, IPL_NONE);

        di->enabled = 1;
        if (kthread_create(PRI_NONE, 0, NULL, _thread, di, NULL,
            "dmdlthread")) {
                printf("Failed to create delay target's kthread\n");
                /* XXX cleanup ? */
                return EINVAL;
        }

        _debug(di, "init");
        return 0;
}

char *
dm_target_delay_info(void *target_config)
{
        dm_target_delay_config_t *tdc;
        char *params;

        tdc = target_config;
        KASSERT(tdc != NULL);

        aprint_debug("Delay target info function called\n");

        params = kmem_alloc(DM_MAX_PARAMS_SIZE, KM_SLEEP);
        snprintf(params, DM_MAX_PARAMS_SIZE, "%d %d", tdc->read.count,
            tdc->write.count);

        return params;
}

char *
dm_target_delay_table(void *target_config)
{
        dm_target_delay_config_t *tdc;
        char *params, *p;

        tdc = target_config;
        KASSERT(tdc != NULL);

        aprint_debug("Delay target table function called\n");

        params = kmem_alloc(DM_MAX_PARAMS_SIZE, KM_SLEEP);
        p = params;
        p += _table(&tdc->read, p);
        if (tdc->argc == 6) {
                p += snprintf(p, DM_MAX_PARAMS_SIZE, " ");
                _table(&tdc->write, p);
        }

        return params;
}

static int
_table(struct dm_delay_info *di, char *p)
{

        return snprintf(p, DM_MAX_PARAMS_SIZE, "%s %" PRIu64 " %d",
            di->pdev->udev_name, di->offset, di->delay);
}

int
dm_target_delay_strategy(dm_table_entry_t *table_en, struct buf *bp)
{
        dm_target_delay_config_t *tdc;
        struct dm_delay_info *di;

        tdc = table_en->target_config;
        KASSERT(tdc != NULL);

        if (bp->b_flags & B_READ)
                di = &tdc->read;
        else
                di = &tdc->write;

        if (di) {
                if (di->delay) {
                        _strategy(di, bp);
                } else {
                        _submit(di, bp);
                }
        } else {
                struct vnode *vnode = tdc->write.pdev->pdev_vnode;
                KASSERT(0);
                VOP_STRATEGY(vnode, bp);
        }

        return 0;
}

static void
_strategy(struct dm_delay_info *di, struct buf *bp)
{
        struct dm_delay_buf *dp;

        dp = pool_get(&pool, PR_WAITOK);
        dp->bp = bp;
        dp->expire = tick + di->delay;

        mutex_enter(&di->buf_mtx);
        di->count++;
        TAILQ_INSERT_TAIL(&di->buf_list, dp, entry);
        mutex_exit(&di->buf_mtx);

        mutex_enter(&di->cal_mtx);
        if (!callout_pending(&di->cal))
                callout_reset(&di->cal, di->delay, _timeout, di);
        mutex_exit(&di->cal_mtx);
}

static __inline void
_submit(struct dm_delay_info *di, struct buf *bp)
{

        _debug(di, "submit");

        bp->b_blkno += di->offset;
        VOP_STRATEGY(di->pdev->pdev_vnode, bp);
}

static void
_submit_queue(struct dm_delay_info *di, int submit_all)
{
        struct dm_delay_buf *dp;
        struct dm_delay_buf_list tmp_list;
        int next = -1;
        int reset = 0;

        _debug(di, "submitq");
        TAILQ_INIT(&tmp_list);

        mutex_enter(&di->buf_mtx);
        while ((dp = TAILQ_FIRST(&di->buf_list)) != NULL) {
                if (submit_all || tick > dp->expire) {
                        TAILQ_REMOVE(&di->buf_list, dp, entry);
                        TAILQ_INSERT_TAIL(&tmp_list, dp, entry);
                        di->count--;
                        continue;
                }
                if (reset == 0) {
                        reset = 1;
                        next = dp->expire;
                } else {
                        next = lmin(next, dp->expire);
                }
        }
        mutex_exit(&di->buf_mtx);

        if (reset) {
                mutex_enter(&di->cal_mtx);
                callout_reset(&di->cal, next - tick, _timeout, di);
                mutex_exit(&di->cal_mtx);
        }

        while ((dp = TAILQ_FIRST(&tmp_list)) != NULL) {
                TAILQ_REMOVE(&tmp_list, dp, entry);
                _submit(di, dp->bp);
                pool_put(&pool, dp);
        }
}

int
dm_target_delay_sync(dm_table_entry_t *table_en)
{
        dm_target_delay_config_t *tdc;
        int cmd;

        tdc = table_en->target_config;
        cmd = 1;

        return VOP_IOCTL(tdc->write.pdev->pdev_vnode, DIOCCACHESYNC, &cmd,
            FREAD | FWRITE, kauth_cred_get());
}

int
dm_target_delay_destroy(dm_table_entry_t *table_en)
{
        dm_target_delay_config_t *tdc;

        tdc = table_en->target_config;
        if (tdc == NULL)
                goto out;

        _destroy(&tdc->read);
        _destroy(&tdc->write);

        kmem_free(tdc, sizeof(*tdc));
out:
        /* Unbusy target so we can unload it */
        dm_target_unbusy(table_en->target);

        return 0;
}

static void
_destroy(struct dm_delay_info *di)
{

        _debug(di, "destroy");

        mutex_enter(&di->token);
        di->enabled = 0;

        mutex_enter(&di->cal_mtx);
        if (callout_pending(&di->cal))
                callout_halt(&di->cal, NULL);
        mutex_exit(&di->cal_mtx);

        _submit_queue(di, 1);
        mutex_exit(&di->token);
        wakeup(di);
        /* XXX race here (DragonFly uses lwkt_token instead of mutex) */
        tsleep(&di->enabled, 0, "dmdldestroy", 0);

        mutex_destroy(&di->token);
        mutex_destroy(&di->cal_mtx);
        mutex_destroy(&di->buf_mtx);

        dm_pdev_decr(di->pdev);
}

#if 0
int
dm_target_delay_upcall(dm_table_entry_t *table_en, struct buf *bp)
{

        return 0;
}
#endif

int
dm_target_delay_secsize(dm_table_entry_t *table_en, unsigned int *secsizep)
{
        dm_target_delay_config_t *tdc;
        unsigned int secsize;

        secsize = 0;

        tdc = table_en->target_config;
        if (tdc != NULL)
                secsize = tdc->write.pdev->pdev_secsize;

        *secsizep = secsize;

        return 0;
}

static void
_timeout(void *arg)
{
        struct dm_delay_info *di = arg;

        _debug(di, "timeout");
        wakeup(di);
}

static void
_thread(void *arg)
{
        struct dm_delay_info *di = arg;

        _debug(di, "thread init");
        mutex_enter(&di->token);

        while (di->enabled) {
                mutex_exit(&di->token);
                tsleep(di, 0, "dmdlthread", 0);
                _submit_queue(di, 0);
                mutex_enter(&di->token);
        }

        mutex_exit(&di->token);
        wakeup(&di->enabled);

        _debug(di, "thread exit");
        kthread_exit(0);
}

static __inline void
_debug(struct dm_delay_info *di, const char *msg)
{

        aprint_debug("%-8s: %d pdev=%s offset=%ju delay=%d count=%d\n",
            msg, di->enabled, di->pdev->name, (uintmax_t)di->offset, di->delay,
            di->count);
}

void
dm_target_delay_pool_create(void)
{

        if (!pool_initialized) {
                pool_init(&pool, sizeof(struct dm_delay_buf), 0, 0, 0,
                    "dmdlobj", &pool_allocator_nointr, IPL_NONE);
                pool_initialized = true;
                aprint_debug("Delay target pool initialized\n");
        }
}

void
dm_target_delay_pool_destroy(void)
{

        if (pool_initialized) {
                pool_destroy(&pool);
                pool_initialized = false;
                aprint_debug("Delay target pool destroyed\n");
        }
}