/*        $NetBSD: dm_target.c,v 1.42 2021/08/21 22:23:33 andvar Exp $      */

/*
 * Copyright (c) 2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Adam Hamsik.
 *
 * 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.c,v 1.42 2021/08/21 22:23:33 andvar Exp $");

#include <sys/types.h>
#include <sys/param.h>
#include <sys/kmem.h>
#include <sys/module.h>

#include "netbsd-dm.h"
#include "dm.h"

static dm_target_t *dm_target_lookup_name(const char *);

TAILQ_HEAD(dm_target_head, dm_target);

static struct dm_target_head dm_target_list =
TAILQ_HEAD_INITIALIZER(dm_target_list);

static kmutex_t dm_target_mutex;

/*
 * Called indirectly from dm_table_load_ioctl to mark target as used.
 */
void
dm_target_busy(dm_target_t *target)
{

        atomic_inc_32(&target->ref_cnt);
}

/*
 * Release reference counter on target.
 */
void
dm_target_unbusy(dm_target_t *target)
{

        KASSERT(target->ref_cnt > 0);
        atomic_dec_32(&target->ref_cnt);
}

/*
 * Try to autoload target module if it was not found in current
 * target list.
 */
dm_target_t *
dm_target_autoload(const char *dm_target_name)
{
        char name[30];
        unsigned int gen;
        dm_target_t *dmt;

        snprintf(name, sizeof(name), "dm_target_%s", dm_target_name);
        name[29] = '\0';

        do {
                gen = module_gen;

                /* Try to autoload target module */
                module_autoload(name, MODULE_CLASS_MISC);
        } while (gen != module_gen);

        mutex_enter(&dm_target_mutex);
        dmt = dm_target_lookup_name(dm_target_name);
        if (dmt != NULL)
                dm_target_busy(dmt);
        mutex_exit(&dm_target_mutex);

        return dmt;
}

/*
 * Lookup for target in global target list.
 */
dm_target_t *
dm_target_lookup(const char *dm_target_name)
{
        dm_target_t *dmt;

        if (dm_target_name == NULL)
                return NULL;

        mutex_enter(&dm_target_mutex);

        dmt = dm_target_lookup_name(dm_target_name);
        if (dmt != NULL)
                dm_target_busy(dmt);

        mutex_exit(&dm_target_mutex);

        return dmt;
}

/*
 * Search for name in TAIL and return appropriate pointer.
 */
static dm_target_t *
dm_target_lookup_name(const char *dm_target_name)
{
        dm_target_t *dm_target;
        size_t dlen;
        size_t slen;

        slen = strlen(dm_target_name) + 1;

        TAILQ_FOREACH(dm_target, &dm_target_list, dm_target_next) {
                dlen = strlen(dm_target->name) + 1;
                if (dlen != slen)
                        continue;

                if (strncmp(dm_target_name, dm_target->name, slen) == 0)
                        return dm_target;
        }

        return NULL;
}

/*
 * Insert new target struct into the TAIL.
 * dm_target
 *   contains name, version, function pointer to specific target functions.
 */
int
dm_target_insert(dm_target_t *dm_target)
{
        dm_target_t *dmt;

        /* Sanity check for any missing function */
        if (dm_target->init == NULL) {
                printf("%s missing init\n", dm_target->name);
                return EINVAL;
        }
        if (dm_target->strategy == NULL) {
                printf("%s missing strategy\n", dm_target->name);
                return EINVAL;
        }
        if (dm_target->destroy == NULL) {
                printf("%s missing destroy\n", dm_target->name);
                return EINVAL;
        }
#if 0
        if (dm_target->upcall == NULL) {
                printf("%s missing upcall\n", dm_target->name);
                return EINVAL;
        }
#endif

        mutex_enter(&dm_target_mutex);

        dmt = dm_target_lookup_name(dm_target->name);
        if (dmt != NULL) {
                mutex_exit(&dm_target_mutex);
                return EEXIST;
        }
        TAILQ_INSERT_TAIL(&dm_target_list, dm_target, dm_target_next);

        mutex_exit(&dm_target_mutex);

        return 0;
}

/*
 * Remove target from TAIL, target is selected with its name.
 */
int
dm_target_rem(const char *dm_target_name)
{
        dm_target_t *dmt;

        KASSERT(dm_target_name != NULL);

        mutex_enter(&dm_target_mutex);

        dmt = dm_target_lookup_name(dm_target_name);
        if (dmt == NULL) {
                mutex_exit(&dm_target_mutex);
                return ENOENT;
        }
        if (dmt->ref_cnt > 0) {
                mutex_exit(&dm_target_mutex);
                return EBUSY;
        }
        TAILQ_REMOVE(&dm_target_list, dmt, dm_target_next);

        mutex_exit(&dm_target_mutex);

        kmem_free(dmt, sizeof(dm_target_t));

        return 0;
}

/*
 * Destroy all targets and remove them from queue.
 * This routine is called from dm_detach, before module
 * is unloaded.
 */
int
dm_target_destroy(void)
{
        dm_target_t *dm_target;

        mutex_enter(&dm_target_mutex);

        while ((dm_target = TAILQ_FIRST(&dm_target_list)) != NULL) {
                TAILQ_REMOVE(&dm_target_list, dm_target, dm_target_next);
                kmem_free(dm_target, sizeof(dm_target_t));
        }
        KASSERT(TAILQ_EMPTY(&dm_target_list));

        mutex_exit(&dm_target_mutex);

        mutex_destroy(&dm_target_mutex);
#if 0
        /* Target specific module destroy routine. */
        dm_target_delay_pool_destroy();
#endif
        return 0;
}

/*
 * Allocate new target entry.
 */
dm_target_t *
dm_target_alloc(const char *name)
{
        dm_target_t *dmt;

        dmt = kmem_zalloc(sizeof(dm_target_t), KM_SLEEP);
        if (dmt == NULL)
                return NULL;

        if (name)
                strlcpy(dmt->name, name, sizeof(dmt->name));

        return dmt;
}

/*
 * Return prop_array of dm_target dictionaries.
 */
prop_array_t
dm_target_prop_list(void)
{
        prop_array_t target_array;
        dm_target_t *dm_target;

        target_array = prop_array_create();

        mutex_enter(&dm_target_mutex);

        TAILQ_FOREACH(dm_target, &dm_target_list, dm_target_next) {
                prop_array_t ver;
                prop_dictionary_t target_dict;
                int i;

                target_dict = prop_dictionary_create();
                ver = prop_array_create();
                prop_dictionary_set_string(target_dict, DM_TARGETS_NAME,
                    dm_target->name);

                for (i = 0; i < 3; i++)
                        prop_array_add_uint32(ver, dm_target->version[i]);

                prop_dictionary_set(target_dict, DM_TARGETS_VERSION, ver);
                prop_array_add(target_array, target_dict);

                prop_object_release(ver);
                prop_object_release(target_dict);
        }

        mutex_exit(&dm_target_mutex);

        return target_array;
}

/*
 * Initialize dm_target subsystem.
 */
int
dm_target_init(void)
{
        dm_target_t *dmt;

        mutex_init(&dm_target_mutex, MUTEX_DEFAULT, IPL_NONE);

        dmt = dm_target_alloc("linear");
        dmt->version[0] = 1;
        dmt->version[1] = 0;
        dmt->version[2] = 2;
        dmt->init = &dm_target_linear_init;
        dmt->table = &dm_target_linear_table;
        dmt->strategy = &dm_target_linear_strategy;
        dmt->sync = &dm_target_linear_sync;
        dmt->destroy = &dm_target_linear_destroy;
        //dmt->upcall = &dm_target_linear_upcall;
        dmt->secsize = &dm_target_linear_secsize;
        if (dm_target_insert(dmt))
                printf("Failed to insert linear\n");

        dmt = dm_target_alloc("striped");
        dmt->version[0] = 1;
        dmt->version[1] = 0;
        dmt->version[2] = 3;
        dmt->init = &dm_target_stripe_init;
        dmt->info = &dm_target_stripe_info;
        dmt->table = &dm_target_stripe_table;
        dmt->strategy = &dm_target_stripe_strategy;
        dmt->sync = &dm_target_stripe_sync;
        dmt->destroy = &dm_target_stripe_destroy;
        //dmt->upcall = &dm_target_stripe_upcall;
        dmt->secsize = &dm_target_stripe_secsize;
        if (dm_target_insert(dmt))
                printf("Failed to insert striped\n");

        dmt = dm_target_alloc("error");
        dmt->version[0] = 1;
        dmt->version[1] = 0;
        dmt->version[2] = 0;
        dmt->init = &dm_target_error_init;
        dmt->strategy = &dm_target_error_strategy;
        dmt->destroy = &dm_target_error_destroy;
        //dmt->upcall = &dm_target_error_upcall;
        if (dm_target_insert(dmt))
                printf("Failed to insert error\n");

        dmt = dm_target_alloc("zero");
        dmt->version[0] = 1;
        dmt->version[1] = 0;
        dmt->version[2] = 0;
        dmt->init = &dm_target_zero_init;
        dmt->strategy = &dm_target_zero_strategy;
        dmt->destroy = &dm_target_zero_destroy;
        //dmt->upcall = &dm_target_zero_upcall;
        if (dm_target_insert(dmt))
                printf("Failed to insert zero\n");
#if 0
        dmt = dm_target_alloc("delay");
        dmt->version[0] = 1;
        dmt->version[1] = 0;
        dmt->version[2] = 0;
        dmt->init = &dm_target_delay_init;
        dmt->info = &dm_target_delay_info;
        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;
        if (dm_target_insert(dmt))
                printf("Failed to insert delay\n");
        dm_target_delay_pool_create();

        dmt = dm_target_alloc("flakey");
        dmt->version[0] = 1;
        dmt->version[1] = 0;
        dmt->version[2] = 0;
        dmt->init = &dm_target_flakey_init;
        dmt->table = &dm_target_flakey_table;
        dmt->strategy = &dm_target_flakey_strategy;
        dmt->sync = &dm_target_flakey_sync;
        dmt->destroy = &dm_target_flakey_destroy;
        //dmt->upcall = &dm_target_flakey_upcall;
        dmt->secsize = &dm_target_flakey_secsize;
        if (dm_target_insert(dmt))
                printf("Failed to insert flakey\n");
#endif
        return 0;
}