[Ventoy.git] / Unix / ventoy_unix_src / FreeBSD / geom_ventoy_src / 12.x / sys / geom / ventoy / g_ventoy.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2020 longpanda <admin@ventoy.net>
 * Copyright (c) 2004-2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
 * All rights reserved.
 *
 * 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 AUTHORS 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 AUTHORS 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>
__FBSDID("$FreeBSD$");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/bio.h>
#include <sys/sbuf.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <geom/geom.h>
#include <geom/ventoy/g_ventoy.h>

FEATURE(geom_ventoy, "GEOM ventoy support");

static MALLOC_DEFINE(M_VENTOY, "ventoy_data", "GEOM_VENTOY Data");

SYSCTL_DECL(_kern_geom);
static SYSCTL_NODE(_kern_geom, OID_AUTO, ventoy, CTLFLAG_RW, 0,
    "GEOM_VENTOY stuff");
static u_int g_ventoy_debug = 0;
SYSCTL_UINT(_kern_geom_ventoy, OID_AUTO, debug, CTLFLAG_RWTUN, &g_ventoy_debug, 0,
    "Debug level");

extern int resource_string_value(const char *name, int unit, const char *resname, const char **result);
extern int resource_int_value(const char *name, int unit, const char *resname, int *result);

static int g_ventoy_destroy(struct g_ventoy_softc *sc, boolean_t force);
static int g_ventoy_destroy_geom(struct gctl_req *req, struct g_class *mp,
    struct g_geom *gp);

static g_taste_t g_ventoy_taste;
static g_ctl_req_t g_ventoy_config;
static g_dumpconf_t g_ventoy_dumpconf;

static char g_ventoy_disk_uuid[64];
static bool g_ventoy_tasted = false;
static off_t g_ventoy_disk_size = 0;
static off_t g_disk_map_start = 0;
static off_t g_disk_map_end = 0;

struct g_ventoy_map g_ventoy_map_data __attribute__((aligned (65536))) = 
{
    { VENTOY_UNIX_SEG_MAGIC0, VENTOY_UNIX_SEG_MAGIC1, VENTOY_UNIX_SEG_MAGIC2, VENTOY_UNIX_SEG_MAGIC3 },
    { 0, 0, 0, 0 },
    0, 0,
    { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
    { { 0, 0 } },
    { VENTOY_UNIX_SEG_MAGIC0, VENTOY_UNIX_SEG_MAGIC1, VENTOY_UNIX_SEG_MAGIC2, VENTOY_UNIX_SEG_MAGIC3 }
};

struct g_class g_ventoy_class = {
        .name = G_VENTOY_CLASS_NAME,
        .version = G_VERSION,
        .ctlreq = g_ventoy_config,
        .taste = g_ventoy_taste,
        .destroy_geom = g_ventoy_destroy_geom
};


/*
 * Greatest Common Divisor.
 */
static u_int
gcd(u_int a, u_int b)
{
        u_int c;

        while (b != 0) {
                c = a;
                a = b;
                b = (c % b);
        }
        return (a);
}

/*
 * Least Common Multiple.
 */
static u_int
lcm(u_int a, u_int b)
{

        return ((a * b) / gcd(a, b));
}

/*
 * Return the number of valid disks.
 */
static u_int
g_ventoy_nvalid(struct g_ventoy_softc *sc)
{
        u_int i, no;

        no = 0;
        for (i = 0; i < sc->sc_ndisks; i++) {
                if (sc->sc_disks[i].d_consumer != NULL)
                        no++;
        }

        return (no);
}

static void
g_ventoy_remove_disk(struct g_ventoy_disk *disk)
{
        struct g_consumer *cp;
        struct g_ventoy_softc *sc;

        g_topology_assert();
        KASSERT(disk->d_consumer != NULL, ("Non-valid disk in %s.", __func__));
        sc = disk->d_softc;
        cp = disk->d_consumer;

        if (!disk->d_removed) {
                G_VENTOY_DEBUG(0, "Disk %s removed from %s.",
                    cp->provider->name, sc->sc_name);
                disk->d_removed = 1;
        }

        if (sc->sc_provider != NULL) {
                G_VENTOY_DEBUG(0, "Device %s deactivated.",
                    sc->sc_provider->name);
                g_wither_provider(sc->sc_provider, ENXIO);
                sc->sc_provider = NULL;
        }

        if (cp->acr > 0 || cp->acw > 0 || cp->ace > 0)
                return;
        disk->d_consumer = NULL;
        g_detach(cp);
        g_destroy_consumer(cp);
        /* If there are no valid disks anymore, remove device. */
        if (LIST_EMPTY(&sc->sc_geom->consumer))
                g_ventoy_destroy(sc, 1);
}

static void
g_ventoy_orphan(struct g_consumer *cp)
{
        struct g_ventoy_softc *sc;
        struct g_ventoy_disk *disk;
        struct g_geom *gp;

        g_topology_assert();
        gp = cp->geom;
        sc = gp->softc;
        if (sc == NULL)
                return;

        disk = cp->private;
        if (disk == NULL)       /* Possible? */
                return;
        g_ventoy_remove_disk(disk);
}

static int
g_ventoy_access(struct g_provider *pp, int dr, int dw, int de)
{
        struct g_consumer *cp1, *cp2, *tmp;
        struct g_ventoy_disk *disk;
        struct g_geom *gp;
        int error;

    if (dw > 0) /* readonly */
                return (EPERM);

        g_topology_assert();
        gp = pp->geom;

        /* On first open, grab an extra "exclusive" bit */
        if (pp->acr == 0 && pp->acw == 0 && pp->ace == 0)
                de++;
        /* ... and let go of it on last close */
        if ((pp->acr + dr) == 0 && (pp->acw + dw) == 0 && (pp->ace + de) == 0)
                de--;

        LIST_FOREACH_SAFE(cp1, &gp->consumer, consumer, tmp) {
                error = g_access(cp1, dr, dw, de);
                if (error != 0)
                        goto fail;
                disk = cp1->private;
                if (cp1->acr == 0 && cp1->acw == 0 && cp1->ace == 0 &&
                    disk->d_removed) {
                        g_ventoy_remove_disk(disk); /* May destroy geom. */
                }
        }
        return (0);

fail:
        LIST_FOREACH(cp2, &gp->consumer, consumer) {
                if (cp1 == cp2)
                        break;
                g_access(cp2, -dr, -dw, -de);
        }
        return (error);
}

static void
g_ventoy_kernel_dump(struct bio *bp)
{
        struct g_ventoy_softc *sc;
        struct g_ventoy_disk *disk;
        struct bio *cbp;
        struct g_kerneldump *gkd;
        u_int i;

        sc = bp->bio_to->geom->softc;
        gkd = (struct g_kerneldump *)bp->bio_data;
        for (i = 0; i < sc->sc_ndisks; i++) {
                if (sc->sc_disks[i].d_start <= gkd->offset &&
                    sc->sc_disks[i].d_end > gkd->offset)
                        break;
        }
        if (i == sc->sc_ndisks)
                g_io_deliver(bp, EOPNOTSUPP);
        disk = &sc->sc_disks[i];
        gkd->offset -= disk->d_start;
        if (gkd->length > disk->d_end - disk->d_start - gkd->offset)
                gkd->length = disk->d_end - disk->d_start - gkd->offset;
        cbp = g_clone_bio(bp);
        if (cbp == NULL) {
                g_io_deliver(bp, ENOMEM);
                return;
        }
        cbp->bio_done = g_std_done;
        g_io_request(cbp, disk->d_consumer);
        G_VENTOY_DEBUG(1, "Kernel dump will go to %s.",
            disk->d_consumer->provider->name);
}

static void
g_ventoy_done(struct bio *bp)
{
        struct g_ventoy_softc *sc;
        struct bio *pbp;

        pbp = bp->bio_parent;
        sc = pbp->bio_to->geom->softc;
        mtx_lock(&sc->sc_lock);
        if (pbp->bio_error == 0)
                pbp->bio_error = bp->bio_error;
        pbp->bio_completed += bp->bio_completed;
        pbp->bio_inbed++;
        if (pbp->bio_children == pbp->bio_inbed) {
                mtx_unlock(&sc->sc_lock);
                g_io_deliver(pbp, pbp->bio_error);
        } else
                mtx_unlock(&sc->sc_lock);
        g_destroy_bio(bp);
}

static void
g_ventoy_flush(struct g_ventoy_softc *sc, struct bio *bp)
{
        struct bio_queue_head queue;
        struct g_consumer *cp;
        struct bio *cbp;
        u_int no;

        bioq_init(&queue);
        for (no = 0; no < sc->sc_ndisks; no++) {
                cbp = g_clone_bio(bp);
                if (cbp == NULL) {
                        while ((cbp = bioq_takefirst(&queue)) != NULL)
                                g_destroy_bio(cbp);
                        if (bp->bio_error == 0)
                                bp->bio_error = ENOMEM;
                        g_io_deliver(bp, bp->bio_error);
                        return;
                }
                bioq_insert_tail(&queue, cbp);
                cbp->bio_done = g_ventoy_done;
                cbp->bio_caller1 = sc->sc_disks[no].d_consumer;
                cbp->bio_to = sc->sc_disks[no].d_consumer->provider;
        }
        while ((cbp = bioq_takefirst(&queue)) != NULL) {
                G_VENTOY_LOGREQ(cbp, "Sending request.");
                cp = cbp->bio_caller1;
                cbp->bio_caller1 = NULL;
                g_io_request(cbp, cp);
        }
}

static void
g_ventoy_start(struct bio *bp)
{
        struct bio_queue_head queue;
        struct g_ventoy_softc *sc;
        struct g_ventoy_disk *disk;
        struct g_provider *pp;
        off_t offset, end, length, off, len;
        struct bio *cbp;
        char *addr;
        u_int no;

        pp = bp->bio_to;
        sc = pp->geom->softc;
        /*
         * If sc == NULL, provider's error should be set and g_ventoy_start()
         * should not be called at all.
         */
        KASSERT(sc != NULL,
            ("Provider's error should be set (error=%d)(device=%s).",
            bp->bio_to->error, bp->bio_to->name));

        G_VENTOY_LOGREQ(bp, "Request received.");

        switch (bp->bio_cmd) {
        case BIO_READ:
        case BIO_WRITE:
        case BIO_DELETE:
                break;
        case BIO_FLUSH:
                g_ventoy_flush(sc, bp);
                return;
        case BIO_GETATTR:
                if (strcmp("GEOM::kerneldump", bp->bio_attribute) == 0) {
                        g_ventoy_kernel_dump(bp);
                        return;
                }
                /* To which provider it should be delivered? */
                /* FALLTHROUGH */
        default:
                g_io_deliver(bp, EOPNOTSUPP);
                return;
        }

        offset = bp->bio_offset;
        length = bp->bio_length;
        if ((bp->bio_flags & BIO_UNMAPPED) != 0)
                addr = NULL;
        else
                addr = bp->bio_data;
        end = offset + length;

        bioq_init(&queue);
        for (no = 0; no < sc->sc_ndisks; no++) {
                disk = &sc->sc_disks[no];
                if (disk->d_end <= offset)
                        continue;
                if (disk->d_start >= end)
                        break;

                off = offset - disk->d_start;
                len = MIN(length, disk->d_end - offset);
                length -= len;
                offset += len;

                cbp = g_clone_bio(bp);
                if (cbp == NULL) {
                        while ((cbp = bioq_takefirst(&queue)) != NULL)
                                g_destroy_bio(cbp);
                        if (bp->bio_error == 0)
                                bp->bio_error = ENOMEM;
                        g_io_deliver(bp, bp->bio_error);
                        return;
                }
                bioq_insert_tail(&queue, cbp);
                /*
                 * Fill in the component buf structure.
                 */
                if (len == bp->bio_length)
                        cbp->bio_done = g_std_done;
                else
                        cbp->bio_done = g_ventoy_done;
                cbp->bio_offset = off + disk->d_map_start;
                cbp->bio_length = len;
                if ((bp->bio_flags & BIO_UNMAPPED) != 0) {
                        cbp->bio_ma_offset += (uintptr_t)addr;
                        cbp->bio_ma += cbp->bio_ma_offset / PAGE_SIZE;
                        cbp->bio_ma_offset %= PAGE_SIZE;
                        cbp->bio_ma_n = round_page(cbp->bio_ma_offset +
                            cbp->bio_length) / PAGE_SIZE;
                } else
                        cbp->bio_data = addr;
                addr += len;
                cbp->bio_to = disk->d_consumer->provider;
                cbp->bio_caller1 = disk;

                if (length == 0)
                        break;
        }
        KASSERT(length == 0,
            ("Length is still greater than 0 (class=%s, name=%s).",
            bp->bio_to->geom->class->name, bp->bio_to->geom->name));
        while ((cbp = bioq_takefirst(&queue)) != NULL) {
                G_VENTOY_LOGREQ(cbp, "Sending request.");
                disk = cbp->bio_caller1;
                cbp->bio_caller1 = NULL;
                g_io_request(cbp, disk->d_consumer);
        }
}

static void
g_ventoy_check_and_run(struct g_ventoy_softc *sc)
{
        struct g_ventoy_disk *disk;
        struct g_provider *dp, *pp;
        u_int no, sectorsize = 0;
        off_t start;

        g_topology_assert();
        if (g_ventoy_nvalid(sc) != sc->sc_ndisks)
                return;

        pp = g_new_providerf(sc->sc_geom, "ventoy/%s", sc->sc_name);
        pp->flags |= G_PF_DIRECT_SEND | G_PF_DIRECT_RECEIVE |
            G_PF_ACCEPT_UNMAPPED;
        start = 0;
        for (no = 0; no < sc->sc_ndisks; no++) {
                disk = &sc->sc_disks[no];
                dp = disk->d_consumer->provider;
                disk->d_start = start;
                disk->d_end = disk->d_start + (disk->d_map_end - disk->d_map_start);
                if (sc->sc_type == G_VENTOY_TYPE_AUTOMATIC)
                        disk->d_end -= dp->sectorsize;
                start = disk->d_end;
                if (no == 0)
                        sectorsize = dp->sectorsize;
                else
                        sectorsize = lcm(sectorsize, dp->sectorsize);

                /* A provider underneath us doesn't support unmapped */
                if ((dp->flags & G_PF_ACCEPT_UNMAPPED) == 0) {
                        G_VENTOY_DEBUG(1, "Cancelling unmapped "
                            "because of %s.", dp->name);
                        pp->flags &= ~G_PF_ACCEPT_UNMAPPED;
                }
        }
        pp->sectorsize = sectorsize;
        /* We have sc->sc_disks[sc->sc_ndisks - 1].d_end in 'start'. */
        pp->mediasize = start;
        pp->stripesize = sc->sc_disks[0].d_consumer->provider->stripesize;
        pp->stripeoffset = sc->sc_disks[0].d_consumer->provider->stripeoffset;
        sc->sc_provider = pp;
        g_error_provider(pp, 0);

        G_VENTOY_DEBUG(0, "Device %s activated.", sc->sc_provider->name);
}

static int
g_ventoy_read_metadata(struct g_consumer *cp, struct g_ventoy_metadata *md)
{
        struct g_provider *pp;
        u_char *buf;
        int error;

        g_topology_assert();

        error = g_access(cp, 1, 0, 0);
        if (error != 0)
                return (error);
        pp = cp->provider;
        g_topology_unlock();
        buf = g_read_data(cp, pp->mediasize - pp->sectorsize, pp->sectorsize,
            &error);
        g_topology_lock();
        g_access(cp, -1, 0, 0);
        if (buf == NULL)
                return (error);

        /* Decode metadata. */
        ventoy_metadata_decode(buf, md);
        g_free(buf);

        return (0);
}

/*
 * Add disk to given device.
 */
static int
g_ventoy_add_disk(struct g_ventoy_softc *sc, struct g_provider *pp, u_int no)
{
        struct g_ventoy_disk *disk;
        struct g_consumer *cp, *fcp;
        struct g_geom *gp;
        int error;

        g_topology_assert();
        /* Metadata corrupted? */
        if (no >= sc->sc_ndisks)
                return (EINVAL);

        disk = &sc->sc_disks[no];
        /* Check if disk is not already attached. */
        if (disk->d_consumer != NULL)
                return (EEXIST);

        gp = sc->sc_geom;
        fcp = LIST_FIRST(&gp->consumer);

        cp = g_new_consumer(gp);
        cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE;
        error = g_attach(cp, pp);
        if (error != 0) {
                g_destroy_consumer(cp);
                return (error);
        }

        if (fcp != NULL && (fcp->acr > 0 || fcp->acw > 0 || fcp->ace > 0)) {
                error = g_access(cp, fcp->acr, fcp->acw, fcp->ace);
                if (error != 0) {
                        g_detach(cp);
                        g_destroy_consumer(cp);
                        return (error);
                }
        }
        if (sc->sc_type == G_VENTOY_TYPE_AUTOMATIC) {
                struct g_ventoy_metadata md;

                /* Re-read metadata. */
                error = g_ventoy_read_metadata(cp, &md);
                if (error != 0)
                        goto fail;

                if (strcmp(md.md_magic, G_VENTOY_MAGIC) != 0 ||
                    strcmp(md.md_name, sc->sc_name) != 0 ||
                    md.md_id != sc->sc_id) {
                        G_VENTOY_DEBUG(0, "Metadata on %s changed.", pp->name);
                        goto fail;
                }
        }

        cp->private = disk;
        disk->d_consumer = cp;
        disk->d_softc = sc;
        disk->d_start = 0;      /* not yet */
        disk->d_end = 0;        /* not yet */
        disk->d_removed = 0;
    
        disk->d_map_start = g_disk_map_start;
        disk->d_map_end = g_disk_map_end;

        G_VENTOY_DEBUG(0, "Disk %s attached to %s.", pp->name, sc->sc_name);

        g_ventoy_check_and_run(sc);

        return (0);
fail:
        if (fcp != NULL && (fcp->acr > 0 || fcp->acw > 0 || fcp->ace > 0))
                g_access(cp, -fcp->acr, -fcp->acw, -fcp->ace);
        g_detach(cp);
        g_destroy_consumer(cp);
        return (error);
}

static struct g_geom *
g_ventoy_create(struct g_class *mp, const struct g_ventoy_metadata *md,
    u_int type)
{
        struct g_ventoy_softc *sc;
        struct g_geom *gp;
        u_int no;

        G_VENTOY_DEBUG(1, "Creating device %s (id=%u).", md->md_name,
            md->md_id);

        /* One disks is minimum. */
        if (md->md_all < 1)
                return (NULL);

        /* Check for duplicate unit */
        LIST_FOREACH(gp, &mp->geom, geom) {
                sc = gp->softc;
                if (sc != NULL && strcmp(sc->sc_name, md->md_name) == 0) {
                        G_VENTOY_DEBUG(0, "Device %s already configured.",
                            gp->name);
                        return (NULL);
                }
        }
        gp = g_new_geomf(mp, "%s", md->md_name);
        sc = malloc(sizeof(*sc), M_VENTOY, M_WAITOK | M_ZERO);
        gp->start = g_ventoy_start;
        gp->spoiled = g_ventoy_orphan;
        gp->orphan = g_ventoy_orphan;
        gp->access = g_ventoy_access;
        gp->dumpconf = g_ventoy_dumpconf;

        sc->sc_id = md->md_id;
        sc->sc_ndisks = md->md_all;
        sc->sc_disks = malloc(sizeof(struct g_ventoy_disk) * sc->sc_ndisks,
            M_VENTOY, M_WAITOK | M_ZERO);
        for (no = 0; no < sc->sc_ndisks; no++)
                sc->sc_disks[no].d_consumer = NULL;
        sc->sc_type = type;
        mtx_init(&sc->sc_lock, "gventoy lock", NULL, MTX_DEF);

        gp->softc = sc;
        sc->sc_geom = gp;
        sc->sc_provider = NULL;

        G_VENTOY_DEBUG(0, "Device %s created (id=%u).", sc->sc_name, sc->sc_id);

        return (gp);
}

static int
g_ventoy_destroy(struct g_ventoy_softc *sc, boolean_t force)
{
        struct g_provider *pp;
        struct g_consumer *cp, *cp1;
        struct g_geom *gp;

        g_topology_assert();

        if (sc == NULL)
                return (ENXIO);

        pp = sc->sc_provider;
        if (pp != NULL && (pp->acr != 0 || pp->acw != 0 || pp->ace != 0)) {
                if (force) {
                        G_VENTOY_DEBUG(0, "Device %s is still open, so it "
                            "can't be definitely removed.", pp->name);
                } else {
                        G_VENTOY_DEBUG(1,
                            "Device %s is still open (r%dw%de%d).", pp->name,
                            pp->acr, pp->acw, pp->ace);
                        return (EBUSY);
                }
        }

        gp = sc->sc_geom;
        LIST_FOREACH_SAFE(cp, &gp->consumer, consumer, cp1) {
                g_ventoy_remove_disk(cp->private);
                if (cp1 == NULL)
                        return (0);     /* Recursion happened. */
        }
        if (!LIST_EMPTY(&gp->consumer))
                return (EINPROGRESS);

        gp->softc = NULL;
        KASSERT(sc->sc_provider == NULL, ("Provider still exists? (device=%s)",
            gp->name));
        free(sc->sc_disks, M_VENTOY);
        mtx_destroy(&sc->sc_lock);
        free(sc, M_VENTOY);

        G_VENTOY_DEBUG(0, "Device %s destroyed.", gp->name);
        g_wither_geom(gp, ENXIO);
        return (0);
}

static int
g_ventoy_destroy_geom(struct gctl_req *req __unused,
    struct g_class *mp __unused, struct g_geom *gp)
{
        struct g_ventoy_softc *sc;

        sc = gp->softc;
        return (g_ventoy_destroy(sc, 0));
}

static bool g_vtoy_check_disk(struct g_class *mp, struct g_provider *pp)
{
    int i;
    bool ret = true;
    uint8_t *buf;
    char uuid[64];
    const char *value;
    struct g_consumer *cp;
        struct g_geom *gp;
    uint8_t mbrdata[] = {
        0xEB, 0x63, 0x90, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,    
        0x56, 0x54, 0x00, 0x47, 0x65, 0x00, 0x48, 0x44, 0x00, 0x52, 0x64, 0x00, 0x20, 0x45, 0x72, 0x0D,
    };
    
    if (g_ventoy_disk_size == 0)
    {
        if (VENTOY_MAP_VALID(g_ventoy_map_data.magic2))
        {
            G_DEBUG("ventoy map data is valid. [OK]\n");

            for (i = 0; i < 16; i++)
            {
                sprintf(uuid + i * 2, "%02x", g_ventoy_map_data.diskuuid[i]);
            }
            snprintf(g_ventoy_disk_uuid, sizeof(g_ventoy_disk_uuid), "%s", uuid);
            g_ventoy_disk_size = g_ventoy_map_data.disksize;
            
            G_DEBUG("ventoy.disksize: %llu\n", (unsigned long long)g_ventoy_disk_size);
            G_DEBUG("ventoy.diskuuid: <%s>\n", g_ventoy_disk_uuid);
        }
        else
        {
            G_DEBUG("ventoy map data is invalid, get from resource\n");
        
            if (resource_string_value("ventoy", 0, "disksize", &value) == 0)
            {
                G_DEBUG("ventoy.disksize: %s\n", value);
                g_ventoy_disk_size = strtouq(value, NULL, 0);
            }

            if (resource_string_value("ventoy", 0, "diskuuid", &value) == 0)
            {
                snprintf(g_ventoy_disk_uuid, sizeof(g_ventoy_disk_uuid), "%s", value);
                G_DEBUG("ventoy.diskuuid: <%s>\n", value);
            }
        }
    }

    if (g_ventoy_disk_size != pp->mediasize)
    {
        return false;
    }

    if (strncmp(pp->name, "cd", 2) == 0 || strchr(pp->name, '/'))
    {
        return false;
    }

    /* read UUID from disk */
    gp = g_new_geomf(mp, "ventoy:taste");
        gp->start = NULL;
        gp->access = g_ventoy_access;
        gp->orphan = g_ventoy_orphan;
        cp = g_new_consumer(gp);
        g_attach(cp, pp);

    g_access(cp, 1, 0, 0);
        g_topology_unlock();
        buf = g_read_data(cp, 0, pp->sectorsize, NULL); 
        g_topology_lock();
        g_access(cp, -1, 0, 0);
    
    g_detach(cp);
        g_destroy_consumer(cp);
        g_destroy_geom(gp);
        gp = NULL;

    if (!buf)
    {
        return false;
    }

    for (i = 0; i < 16; i++)
    {
        sprintf(uuid + i * 2, "%02x", buf[0x180 + i]);
    }

    if (strncmp(g_ventoy_disk_uuid, uuid, 32))
    {
        ret = false;
    }

    if (memcmp(mbrdata, buf, 0x30) || memcmp(mbrdata + 0x30, buf + 0x190, 16))
    {
        ret = false;
    }

    g_free(buf);

    if (ret)
    {
        G_DEBUG("ventoy disk check OK\n");
    }

    return ret;
}

static struct g_geom *
g_ventoy_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
{
    int i;
        int error;
    int disknum;
    char *endpos;
    const char *value;
        struct g_geom *gp;
        struct g_ventoy_metadata md;
        struct g_ventoy_softc *sc;

    if (g_ventoy_tasted)
    {
        return NULL;
    }

        G_DEBUG("%s(%s, %s)\n", __func__, mp->name, pp->name);
        g_topology_assert();

        /* Skip providers that are already open for writing. */
        if (pp->acw > 0)
                return (NULL);

    if (!g_vtoy_check_disk(mp, pp))
    {
        return NULL;
    }

    g_ventoy_tasted = true;

    G_DEBUG("######### ventoy disk <%s> #############\n", pp->name);

    if (VENTOY_MAP_VALID(g_ventoy_map_data.magic2))
    {
        disknum = (int)g_ventoy_map_data.segnum;
        G_DEBUG("segnum from map data is:<%d>\n", disknum);
    }
    else
    {
        resource_int_value("ventoy", 0, "segnum", &disknum);
        G_DEBUG("segnum from resource is:<%d>\n", disknum);
    }

    strlcpy(md.md_magic, G_VENTOY_MAGIC, sizeof(md.md_magic));
        md.md_version = G_VENTOY_VERSION;
        strlcpy(md.md_name, "IMAGE", sizeof(md.md_name));
        md.md_id = arc4random();
        md.md_no = 0;
        md.md_all = (uint16_t)disknum;
        bzero(md.md_provider, sizeof(md.md_provider));
        /* This field is not important here. */
        md.md_provsize = 0;

        gp = g_ventoy_create(mp, &md, G_VENTOY_TYPE_MANUAL);
        if (gp == NULL) {
                G_VENTOY_DEBUG(0, "Cannot create device %s.",
                    md.md_name);
                return (NULL);
        }
        sc = gp->softc;

    for (i = 0; i < disknum; i ++)
    {
        if (VENTOY_MAP_VALID(g_ventoy_map_data.magic2))
        {
            G_DEBUG("[map] ventoy segment%d: 0x%llx@0x%llx\n", i, 
                (long long)g_ventoy_map_data.seglist[i].seg_start_bytes,
                (long long)g_ventoy_map_data.seglist[i].seg_end_bytes);
            
            g_disk_map_start = (off_t)g_ventoy_map_data.seglist[i].seg_start_bytes;
            g_disk_map_end = (off_t)g_ventoy_map_data.seglist[i].seg_end_bytes;
        }
        else
        {
            if (resource_string_value("ventoy", i, "seg", &value) == 0)
            {
                g_disk_map_start = strtouq(value, &endpos, 0);
                g_disk_map_end = strtouq(endpos + 1, NULL, 0);
            }
            else
            {
                printf("Failed to parse ventoy seg %d\n", i);
                continue;
            }
            G_DEBUG("[resource] ventoy segment%d: %s\n", i, value);
        }
        
        G_VENTOY_DEBUG(1, "Adding disk %s to %s.", pp->name, gp->name);
        error = g_ventoy_add_disk(sc, pp, i);
        if (error != 0) {
                G_VENTOY_DEBUG(0,
                    "Cannot add disk %s to %s (error=%d).", pp->name,
                    gp->name, error);
                g_ventoy_destroy(sc, 1);
                return (NULL);
        }
        
        g_disk_map_start = 0;
        g_disk_map_end = 0;
    }

        return (gp);
}

static void
g_ventoy_ctl_create(struct gctl_req *req, struct g_class *mp)
{
        u_int attached, no;
        struct g_ventoy_metadata md;
        struct g_provider *pp;
        struct g_ventoy_softc *sc;
        struct g_geom *gp;
        struct sbuf *sb;
        const char *name;
        char param[16];
        int *nargs;

        g_topology_assert();
        nargs = gctl_get_paraml(req, "nargs", sizeof(*nargs));
        if (nargs == NULL) {
                gctl_error(req, "No '%s' argument.", "nargs");
                return;
        }
        if (*nargs < 2) {
                gctl_error(req, "Too few arguments.");
                return;
        }

        strlcpy(md.md_magic, G_VENTOY_MAGIC, sizeof(md.md_magic));
        md.md_version = G_VENTOY_VERSION;
        name = gctl_get_asciiparam(req, "arg0");
        if (name == NULL) {
                gctl_error(req, "No 'arg%u' argument.", 0);
                return;
        }
        strlcpy(md.md_name, name, sizeof(md.md_name));
        md.md_id = arc4random();
        md.md_no = 0;
        md.md_all = *nargs - 1;
        bzero(md.md_provider, sizeof(md.md_provider));
        /* This field is not important here. */
        md.md_provsize = 0;

        /* Check all providers are valid */
        for (no = 1; no < *nargs; no++) {
                snprintf(param, sizeof(param), "arg%u", no);
                name = gctl_get_asciiparam(req, param);
                if (name == NULL) {
                        gctl_error(req, "No 'arg%u' argument.", no);
                        return;
                }
                if (strncmp(name, "/dev/", strlen("/dev/")) == 0)
                        name += strlen("/dev/");
                pp = g_provider_by_name(name);
                if (pp == NULL) {
                        G_VENTOY_DEBUG(1, "Disk %s is invalid.", name);
                        gctl_error(req, "Disk %s is invalid.", name);
                        return;
                }
        }

        gp = g_ventoy_create(mp, &md, G_VENTOY_TYPE_MANUAL);
        if (gp == NULL) {
                gctl_error(req, "Can't configure %s.", md.md_name);
                return;
        }

        sc = gp->softc;
        sb = sbuf_new_auto();
        sbuf_printf(sb, "Can't attach disk(s) to %s:", gp->name);
        for (attached = 0, no = 1; no < *nargs; no++) {
                snprintf(param, sizeof(param), "arg%u", no);
                name = gctl_get_asciiparam(req, param);
                if (name == NULL) {
                        gctl_error(req, "No 'arg%d' argument.", no);
                        return;
                }
                if (strncmp(name, "/dev/", strlen("/dev/")) == 0)
                        name += strlen("/dev/");
                pp = g_provider_by_name(name);
                KASSERT(pp != NULL, ("Provider %s disappear?!", name));
                if (g_ventoy_add_disk(sc, pp, no - 1) != 0) {
                        G_VENTOY_DEBUG(1, "Disk %u (%s) not attached to %s.",
                            no, pp->name, gp->name);
                        sbuf_printf(sb, " %s", pp->name);
                        continue;
                }
                attached++;
        }
        sbuf_finish(sb);
        if (md.md_all != attached) {
                g_ventoy_destroy(gp->softc, 1);
                gctl_error(req, "%s", sbuf_data(sb));
        }
        sbuf_delete(sb);
}

static struct g_ventoy_softc *
g_ventoy_find_device(struct g_class *mp, const char *name)
{
        struct g_ventoy_softc *sc;
        struct g_geom *gp;

        LIST_FOREACH(gp, &mp->geom, geom) {
                sc = gp->softc;
                if (sc == NULL)
                        continue;
                if (strcmp(sc->sc_name, name) == 0)
                        return (sc);
        }
        return (NULL);
}

static void
g_ventoy_ctl_destroy(struct gctl_req *req, struct g_class *mp)
{
        struct g_ventoy_softc *sc;
        int *force, *nargs, error;
        const char *name;
        char param[16];
        u_int i;

        g_topology_assert();

        nargs = gctl_get_paraml(req, "nargs", sizeof(*nargs));
        if (nargs == NULL) {
                gctl_error(req, "No '%s' argument.", "nargs");
                return;
        }
        if (*nargs <= 0) {
                gctl_error(req, "Missing device(s).");
                return;
        }
        force = gctl_get_paraml(req, "force", sizeof(*force));
        if (force == NULL) {
                gctl_error(req, "No '%s' argument.", "force");
                return;
        }

        for (i = 0; i < (u_int)*nargs; i++) {
                snprintf(param, sizeof(param), "arg%u", i);
                name = gctl_get_asciiparam(req, param);
                if (name == NULL) {
                        gctl_error(req, "No 'arg%u' argument.", i);
                        return;
                }
                sc = g_ventoy_find_device(mp, name);
                if (sc == NULL) {
                        gctl_error(req, "No such device: %s.", name);
                        return;
                }
                error = g_ventoy_destroy(sc, *force);
                if (error != 0) {
                        gctl_error(req, "Cannot destroy device %s (error=%d).",
                            sc->sc_name, error);
                        return;
                }
        }
}

static void
g_ventoy_config(struct gctl_req *req, struct g_class *mp, const char *verb)
{
        uint32_t *version;

    return;
    
        g_topology_assert();
    
        version = gctl_get_paraml(req, "version", sizeof(*version));
        if (version == NULL) {
                gctl_error(req, "No '%s' argument.", "version");
                return;
        }
        if (*version != G_VENTOY_VERSION) {
                gctl_error(req, "Userland and kernel parts are out of sync.");
                return;
        }

        if (strcmp(verb, "create") == 0) {
                g_ventoy_ctl_create(req, mp);
                return;
        } else if (strcmp(verb, "destroy") == 0 ||
            strcmp(verb, "stop") == 0) {
                g_ventoy_ctl_destroy(req, mp);
                return;
        }
        gctl_error(req, "Unknown verb.");
}

static void
g_ventoy_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp,
    struct g_consumer *cp, struct g_provider *pp)
{
        struct g_ventoy_softc *sc;

        g_topology_assert();
        sc = gp->softc;
        if (sc == NULL)
                return;
        if (pp != NULL) {
                /* Nothing here. */
        } else if (cp != NULL) {
                struct g_ventoy_disk *disk;

                disk = cp->private;
                if (disk == NULL)
                        return;
                sbuf_printf(sb, "%s<End>%jd</End>\n", indent,
                    (intmax_t)disk->d_end);
                sbuf_printf(sb, "%s<Start>%jd</Start>\n", indent,
                    (intmax_t)disk->d_start);
        } else {
                sbuf_printf(sb, "%s<ID>%u</ID>\n", indent, (u_int)sc->sc_id);
                sbuf_printf(sb, "%s<Type>", indent);
                switch (sc->sc_type) {
                case G_VENTOY_TYPE_AUTOMATIC:
                        sbuf_cat(sb, "AUTOMATIC");
                        break;
                case G_VENTOY_TYPE_MANUAL:
                        sbuf_cat(sb, "MANUAL");
                        break;
                default:
                        sbuf_cat(sb, "UNKNOWN");
                        break;
                }
                sbuf_cat(sb, "</Type>\n");
                sbuf_printf(sb, "%s<Status>Total=%u, Online=%u</Status>\n",
                    indent, sc->sc_ndisks, g_ventoy_nvalid(sc));
                sbuf_printf(sb, "%s<State>", indent);
                if (sc->sc_provider != NULL && sc->sc_provider->error == 0)
                        sbuf_cat(sb, "UP");
                else
                        sbuf_cat(sb, "DOWN");
                sbuf_cat(sb, "</State>\n");
        }
}

DECLARE_GEOM_CLASS(g_ventoy_class, g_ventoy);
//MODULE_VERSION(geom_ventoy, 0);