/*$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;
}