/*$NetBSD: dm_target_stripe.c,v 1.45 2024/09/08 09:36:50 rillig Exp $*/

/*
 * Copyright (c) 2009 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_stripe.c,v 1.45 2024/09/08 09:36:50 rillig Exp $");

/*
 * This file implements initial version of device-mapper stripe target.
 */
#include <sys/types.h>
#include <sys/param.h>
#include <sys/buf.h>
#include <sys/kmem.h>
#include <sys/lwp.h>

#include "dm.h"

typedef struct target_stripe_config {
#define DM_STRIPE_DEV_OFFSET 2
        struct target_linear_devs stripe_devs;
        uint8_t stripe_num;
        uint64_t stripe_chunksize;
} dm_target_stripe_config_t;

#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_stripe, NULL);

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

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

                dmt->version[0] = 1;
                dmt->version[1] = 0;
                dmt->version[2] = 0;
                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;

                r = dm_target_insert(dmt);

                break;

        case MODULE_CMD_FINI:
                r = dm_target_rem("striped");
                break;

        case MODULE_CMD_STAT:
                return ENOTTY;

        default:
                return ENOTTY;
        }

        return r;
}
#endif

static void
dm_target_stripe_fini(dm_target_stripe_config_t *tsc)
{
        dm_target_linear_config_t *tlc;

        if (tsc == NULL)
                return;

        while ((tlc = TAILQ_FIRST(&tsc->stripe_devs)) != NULL) {
                TAILQ_REMOVE(&tsc->stripe_devs, tlc, entries);
                dm_pdev_decr(tlc->pdev);
                kmem_free(tlc, sizeof(*tlc));
        }

        kmem_free(tsc, sizeof(*tsc));
}

/*
 * Init function called from dm_table_load_ioctl.
 * DM_STRIPE_DEV_OFFSET should always hold the index of the first device-offset
 * pair in the parameters.
 * Example line sent to dm from lvm tools when using striped target.
 * start length striped #stripes chunk_size device1 offset1 ... deviceN offsetN
 * 0 65536 striped 2 512 /dev/hda 0 /dev/hdb 0
 */
int
dm_target_stripe_init(dm_table_entry_t *table_en, int argc, char **argv)
{
        dm_target_linear_config_t *tlc;
        dm_target_stripe_config_t *tsc;
        int strpc, strpi;

        if (argc < 2) {
                printf("Stripe target takes at least 2 args, %d given\n", argc);
                return EINVAL;
        }

        printf("Stripe target init function called!!\n");
        printf("Stripe target chunk size %s number of stripes %s\n",
            argv[1], argv[0]);

        tsc = kmem_alloc(sizeof(*tsc), KM_SLEEP);

        /* Initialize linked list for striping devices */
        TAILQ_INIT(&tsc->stripe_devs);

        /* Save length of param string */
        tsc->stripe_chunksize = atoi64(argv[1]);
        tsc->stripe_num = (uint8_t) atoi64(argv[0]);

        strpc = DM_STRIPE_DEV_OFFSET + (tsc->stripe_num * 2);
        for (strpi = DM_STRIPE_DEV_OFFSET; strpi < strpc; strpi += 2) {
                printf("Stripe target device name %s -- offset %s\n",
                       argv[strpi], argv[strpi+1]);

                tlc = kmem_alloc(sizeof(*tlc), KM_SLEEP);
                if ((tlc->pdev = dm_pdev_insert(argv[strpi])) == NULL) {
                        kmem_free(tlc, sizeof(*tlc));
                        dm_target_stripe_fini(tsc);
                        return ENOENT;
                }
                tlc->offset = atoi64(argv[strpi+1]);
                dm_table_add_deps(table_en, tlc->pdev);

                /* Insert striping device to linked list. */
                TAILQ_INSERT_TAIL(&tsc->stripe_devs, tlc, entries);
        }

        table_en->target_config = tsc;

        return 0;
}

/* Info routine called to get params string. */
char *
dm_target_stripe_info(void *target_config)
{
        dm_target_linear_config_t *tlc;
        dm_target_stripe_config_t *tsc;
        char *params, *ptr, buf[256];
        int ret, i = 0;
        size_t len;

        tsc = target_config;

        len = DM_MAX_PARAMS_SIZE;
        params = kmem_alloc(len, KM_SLEEP);
        ptr = params;

        ret = snprintf(ptr, len, "%d ", tsc->stripe_num);
        ptr += ret;
        len -= ret;

        memset(buf, 0, sizeof(buf));
        TAILQ_FOREACH(tlc, &tsc->stripe_devs, entries) {
                ret = snprintf(ptr, len, "%s ", tlc->pdev->udev_name);
                if (0 /*tlc->num_error*/)
                        buf[i] = 'D';
                else
                        buf[i] = 'A';
                i++;
                ptr += ret;
                len -= ret;
        }

        ret = snprintf(ptr, len, "1 %s", buf);
        ptr += ret;
        len -= ret;

        return params;
}

/* Table routine called to get params string. */
char *
dm_target_stripe_table(void *target_config)
{
        dm_target_linear_config_t *tlc;
        dm_target_stripe_config_t *tsc;
        char *params, *tmp;

        tsc = target_config;

        params = kmem_alloc(DM_MAX_PARAMS_SIZE, KM_SLEEP);
        tmp = kmem_alloc(DM_MAX_PARAMS_SIZE, KM_SLEEP);

        snprintf(params, DM_MAX_PARAMS_SIZE, "%d %" PRIu64,
            tsc->stripe_num, tsc->stripe_chunksize);

        TAILQ_FOREACH(tlc, &tsc->stripe_devs, entries) {
                snprintf(tmp, DM_MAX_PARAMS_SIZE, " %s %" PRIu64,
                    tlc->pdev->udev_name, tlc->offset);
                strcat(params, tmp);
        }

        kmem_free(tmp, DM_MAX_PARAMS_SIZE);

        return params;
}

/* Strategy routine called from dm_strategy. */
int
dm_target_stripe_strategy(dm_table_entry_t *table_en, struct buf *bp)
{
        dm_target_linear_config_t *tlc;
        dm_target_stripe_config_t *tsc;
        struct buf *nestbuf;
        uint64_t blkno, blkoff;
        uint64_t stripe, stripe_blknr;
        uint32_t stripe_off, stripe_rest, num_blks, issue_blks;
        int i, stripe_devnr;

        tsc = table_en->target_config;
        if (tsc == NULL)
                return 0;

        /* calculate extent of request */
        KASSERT(bp->b_resid % DEV_BSIZE == 0);

        blkno = bp->b_blkno;
        blkoff = 0;
        num_blks = bp->b_resid / DEV_BSIZE;
        for (;;) {
                /* blockno to stripe piece nr */
                stripe = blkno / tsc->stripe_chunksize;
                stripe_off = blkno % tsc->stripe_chunksize;

                /* where we are inside the stripe */
                stripe_devnr = stripe % tsc->stripe_num;
                stripe_blknr = stripe / tsc->stripe_num;

                /* how much is left before we hit a boundary */
                stripe_rest = tsc->stripe_chunksize - stripe_off;

                /* issue this piece on stripe `stripe' */
                issue_blks = MIN(stripe_rest, num_blks);
                nestbuf = getiobuf(NULL, true);

                nestiobuf_setup(bp, nestbuf, blkoff, issue_blks * DEV_BSIZE);
                nestbuf->b_blkno = stripe_blknr * tsc->stripe_chunksize + stripe_off;

                tlc = TAILQ_FIRST(&tsc->stripe_devs);
                for (i = 0; i < stripe_devnr && tlc != NULL; i++)
                        tlc = TAILQ_NEXT(tlc, entries);

                /* by this point we should have a tlc */
                KASSERT(tlc != NULL);

                nestbuf->b_blkno += tlc->offset;

                VOP_STRATEGY(tlc->pdev->pdev_vnode, nestbuf);

                blkno += issue_blks;
                blkoff += issue_blks * DEV_BSIZE;
                num_blks -= issue_blks;

                if (num_blks <= 0)
                        break;
        }

        return 0;
}

/* Sync underlying disk caches. */
int
dm_target_stripe_sync(dm_table_entry_t *table_en)
{
        int cmd, err;
        dm_target_stripe_config_t *tsc;
        dm_target_linear_config_t *tlc;

        tsc = table_en->target_config;

        err = 0;
        cmd = 1;

        TAILQ_FOREACH(tlc, &tsc->stripe_devs, entries) {
                if ((err = VOP_IOCTL(tlc->pdev->pdev_vnode, DIOCCACHESYNC,
                            &cmd, FREAD|FWRITE, kauth_cred_get())) != 0)
                        return err;
        }

        return err;

}

/* Destroy target specific data. */
int
dm_target_stripe_destroy(dm_table_entry_t *table_en)
{

        dm_target_stripe_fini(table_en->target_config);

        /* Unbusy target so we can unload it */
        dm_target_unbusy(table_en->target);

        return 0;
}

#if 0
/* Unsupported for this target. */
int
dm_target_stripe_upcall(dm_table_entry_t *table_en, struct buf *bp)
{

        return 0;
}
#endif

/*
 * Compute physical block size
 * For a stripe target we chose the maximum sector size of all
 * stripe devices. For the supported power-of-2 sizes this is equivalent
 * to the least common multiple.
 */
int
dm_target_stripe_secsize(dm_table_entry_t *table_en, unsigned int *secsizep)
{
        dm_target_linear_config_t *tlc;
        dm_target_stripe_config_t *tsc;
        unsigned int secsize;

        secsize = 0;

        tsc = table_en->target_config;
        if (tsc != NULL) {
                TAILQ_FOREACH(tlc, &tsc->stripe_devs, entries) {
                        if (secsize < tlc->pdev->pdev_secsize)
                                secsize = tlc->pdev->pdev_secsize;
                }
        }

        *secsizep = secsize;

        return 0;
}