/*        $NetBSD: dm_table.c,v 1.21 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_table.c,v 1.21 2021/08/21 22:23:33 andvar Exp $");

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

#include "dm.h"

/*
 * There are two types of users of this interface:
 *
 * a) Readers such as
 *    dmstrategy, dmgetdisklabel, dmsize, dm_dev_status_ioctl,
 *    dm_table_deps_ioctl, dm_table_status_ioctl, dm_table_reload_ioctl
 *
 * b) Writers such as
 *    dm_dev_remove_ioctl, dm_dev_resume_ioctl, dm_table_clear_ioctl
 *
 * Writers can work with table_head only when there are no readers. I
 * use reference counting on io_cnt.
 *
 */

static int dm_table_busy(dm_table_head_t *, uint8_t);
static void dm_table_unbusy(dm_table_head_t *);
static void dm_table_free_deps(dm_table_entry_t *);


/*
 * Function to increment table user reference counter. Return id
 * of table_id table.
 * DM_TABLE_ACTIVE will return active table id.
 * DM_TABLE_INACTIVE will return inactive table id.
 */
static int
dm_table_busy(dm_table_head_t *head, uint8_t table_id)
{
        uint8_t id;

        mutex_enter(&head->table_mtx);

        if (table_id == DM_TABLE_ACTIVE)
                id = head->cur_active_table;
        else
                id = 1 - head->cur_active_table;

        head->io_cnt++;

        mutex_exit(&head->table_mtx);
        return id;
}

/*
 * Function release table lock and eventually wakeup all waiters.
 */
static void
dm_table_unbusy(dm_table_head_t *head)
{

        KASSERT(head->io_cnt != 0);

        mutex_enter(&head->table_mtx);

        if (--head->io_cnt == 0)
                cv_broadcast(&head->table_cv);

        mutex_exit(&head->table_mtx);
}

/*
 * Return current active table to caller, increment io_cnt reference counter.
 */
dm_table_t *
dm_table_get_entry(dm_table_head_t *head, uint8_t table_id)
{
        uint8_t id;

        id = dm_table_busy(head, table_id);

        return &head->tables[id];
}
/*
 * Decrement io reference counter and wake up all callers, with table_head cv.
 */
void
dm_table_release(dm_table_head_t *head, uint8_t table_id)
{

        dm_table_unbusy(head);
}

/*
 * Switch table from inactive to active mode. Have to wait until io_cnt is 0.
 */
void
dm_table_switch_tables(dm_table_head_t *head)
{

        mutex_enter(&head->table_mtx);

        while (head->io_cnt != 0)
                cv_wait(&head->table_cv, &head->table_mtx);

        head->cur_active_table = 1 - head->cur_active_table;

        mutex_exit(&head->table_mtx);
}

/*
 * Destroy all table data. This function can run when there are no
 * readers on table lists.
 *
 * XXX Is it ok to call kmem_free and potentially VOP_CLOSE with held mutex ?xs
 */
int
dm_table_destroy(dm_table_head_t *head, uint8_t table_id)
{
        dm_table_t *tbl;
        dm_table_entry_t *table_en;
        uint8_t id;

        mutex_enter(&head->table_mtx);

        aprint_debug("dm_Table_destroy called with %d--%d\n", table_id, head->io_cnt);

        while (head->io_cnt != 0)
                cv_wait(&head->table_cv, &head->table_mtx);

        if (table_id == DM_TABLE_ACTIVE)
                id = head->cur_active_table;
        else
                id = 1 - head->cur_active_table;

        tbl = &head->tables[id];

        while ((table_en = SLIST_FIRST(tbl)) != NULL) {
                SLIST_REMOVE(tbl, table_en, dm_table_entry, next);
                if (table_en->target->destroy(table_en) == 0)
                        table_en->target_config = NULL;
                dm_table_free_deps(table_en);
                kmem_free(table_en, sizeof(*table_en));
        }
        KASSERT(SLIST_EMPTY(tbl));

        mutex_exit(&head->table_mtx);

        return 0;
}

/*
 * Return length of active table in device.
 */
static uint64_t
dm_table_size_impl(dm_table_head_t *head, int table)
{
        dm_table_t *tbl;
        dm_table_entry_t *table_en;
        uint64_t length;
        uint8_t id;

        length = 0;

        id = dm_table_busy(head, table);

        /* Select active table */
        tbl = &head->tables[id];

        /*
         * Find out what tables I want to select.
         * if length => rawblkno then we should used that table.
         */
        SLIST_FOREACH(table_en, tbl, next)
                length += table_en->length;

        dm_table_unbusy(head);

        return length;
}

/*
 * Return length of active table in device.
 */
uint64_t
dm_table_size(dm_table_head_t *head)
{

        return dm_table_size_impl(head, DM_TABLE_ACTIVE);
}

/*
 * Return length of active table in device.
 */
uint64_t
dm_inactive_table_size(dm_table_head_t *head)
{

        return dm_table_size_impl(head, DM_TABLE_INACTIVE);
}

/*
 * Return combined disk geometry
 */
void
dm_table_disksize(dm_table_head_t *head, uint64_t *numsecp,
    unsigned int *secsizep)
{
        dm_table_t *tbl;
        dm_table_entry_t *table_en;
        uint64_t length;
        unsigned int secsize, tsecsize;
        uint8_t id;

        length = 0;

        id = dm_table_busy(head, DM_TABLE_ACTIVE);

        /* Select active table */
        tbl = &head->tables[id];

        /*
         * Find out what tables I want to select.
         * if length => rawblkno then we should used that table.
         */
        secsize = 0;
        SLIST_FOREACH(table_en, tbl, next) {
                length += table_en->length;
                if (table_en->target->secsize)
                        table_en->target->secsize(table_en, &tsecsize);
                else
                        tsecsize = 0;
                if (secsize < tsecsize)
                        secsize = tsecsize;
        }

        if (numsecp)
                *numsecp = secsize > 0 ? dbtob(length) / secsize : 0;
        if (secsizep)
                *secsizep = secsize;

        dm_table_unbusy(head);
}

/*
 * Return > 0 if table is at least one table entry (returns number of entries)
 * and return 0 if there is not. Target count returned from this function
 * doesn't need to be true when userspace user receives it (after return
 * there can be dm_dev_resume_ioctl), therefore this is only informative.
 */
int
dm_table_get_target_count(dm_table_head_t *head, uint8_t table_id)
{
        dm_table_entry_t *table_en;
        dm_table_t *tbl;
        uint32_t target_count;
        uint8_t id;

        target_count = 0;

        id = dm_table_busy(head, table_id);
        tbl = &head->tables[id];

        SLIST_FOREACH(table_en, tbl, next)
                target_count++;

        dm_table_unbusy(head);

        return target_count;
}

/*
 * Initialize table_head structures, I'm trying to keep this structure as
 * opaque as possible.
 */
void
dm_table_head_init(dm_table_head_t *head)
{

        head->cur_active_table = 0;
        head->io_cnt = 0;

        /* Initialize tables. */
        SLIST_INIT(&head->tables[0]);
        SLIST_INIT(&head->tables[1]);

        mutex_init(&head->table_mtx, MUTEX_DEFAULT, IPL_NONE);
        cv_init(&head->table_cv, "dm_io");
}

/*
 * Destroy all variables in table_head
 */
void
dm_table_head_destroy(dm_table_head_t *head)
{

        KASSERT(!mutex_owned(&head->table_mtx));
        KASSERT(!cv_has_waiters(&head->table_cv));
        /* tables don't exist when I call this routine, therefore it
         * doesn't make sense to have io_cnt != 0 */
        KASSERT(head->io_cnt == 0);

        cv_destroy(&head->table_cv);
        mutex_destroy(&head->table_mtx);
}

int
dm_table_add_deps(dm_table_entry_t *table_en, dm_pdev_t *pdev)
{
        dm_table_head_t *head;
        dm_mapping_t *map;

        if (!pdev)
                return -1;

        head = &table_en->dm_dev->table_head;
        mutex_enter(&head->table_mtx);

        TAILQ_FOREACH(map, &table_en->pdev_maps, next) {
                if (map->data.pdev->pdev_vnode->v_rdev ==
                    pdev->pdev_vnode->v_rdev) {
                        mutex_exit(&head->table_mtx);
                        return -1;
                }
        }

        map = kmem_alloc(sizeof(*map), KM_SLEEP);
        map->data.pdev = pdev;
        aprint_debug("%s: %s\n", __func__, pdev->name);
        TAILQ_INSERT_TAIL(&table_en->pdev_maps, map, next);

        mutex_exit(&head->table_mtx);

        return 0;
}

/* caller must hold ->table_mtx */
static void
dm_table_free_deps(dm_table_entry_t *table_en)
{
        dm_mapping_t *map;

        while ((map = TAILQ_FIRST(&table_en->pdev_maps)) != NULL) {
                TAILQ_REMOVE(&table_en->pdev_maps, map, next);
                aprint_debug("%s: %s\n", __func__, map->data.pdev->name);
                kmem_free(map, sizeof(*map));
        }
        KASSERT(TAILQ_EMPTY(&table_en->pdev_maps));
}