/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2006 Ruslan Ermilov <ru@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 AUTHOR 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 AUTHOR 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/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/sysctl.h>
#include <sys/malloc.h>
#include <sys/queue.h>
#include <sys/sbuf.h>
#include <sys/time.h>
#include <vm/uma.h>
#include <geom/geom.h>
#include <geom/geom_dbg.h>
#include <geom/cache/g_cache.h>

FEATURE(geom_cache, "GEOM cache module");

static MALLOC_DEFINE(M_GCACHE, "gcache_data", "GEOM_CACHE Data");

SYSCTL_DECL(_kern_geom);
static SYSCTL_NODE(_kern_geom, OID_AUTO, cache, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "GEOM_CACHE stuff");
static u_int g_cache_debug = 0;
SYSCTL_UINT(_kern_geom_cache, OID_AUTO, debug, CTLFLAG_RW, &g_cache_debug, 0,
    "Debug level");
static u_int g_cache_enable = 1;
SYSCTL_UINT(_kern_geom_cache, OID_AUTO, enable, CTLFLAG_RW, &g_cache_enable, 0,
    "");
static u_int g_cache_timeout = 10;
SYSCTL_UINT(_kern_geom_cache, OID_AUTO, timeout, CTLFLAG_RW, &g_cache_timeout,
    0, "");
static u_int g_cache_idletime = 5;
SYSCTL_UINT(_kern_geom_cache, OID_AUTO, idletime, CTLFLAG_RW, &g_cache_idletime,
    0, "");
static u_int g_cache_used_lo = 5;
static u_int g_cache_used_hi = 20;
static int
sysctl_handle_pct(SYSCTL_HANDLER_ARGS)
{
        u_int val = *(u_int *)arg1;
        int error;

        error = sysctl_handle_int(oidp, &val, 0, req);
        if (error || !req->newptr)
                return (error);
        if (val > 100)
                return (EINVAL);
        if ((arg1 == &g_cache_used_lo && val > g_cache_used_hi) ||
            (arg1 == &g_cache_used_hi && g_cache_used_lo > val))
                return (EINVAL);
        *(u_int *)arg1 = val;
        return (0);
}
SYSCTL_PROC(_kern_geom_cache, OID_AUTO, used_lo,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_MPSAFE, &g_cache_used_lo, 0,
    sysctl_handle_pct, "IU",
    "");
SYSCTL_PROC(_kern_geom_cache, OID_AUTO, used_hi,
    CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_MPSAFE, &g_cache_used_hi, 0,
    sysctl_handle_pct, "IU",
    "");

static int g_cache_destroy(struct g_cache_softc *sc, boolean_t force);
static g_ctl_destroy_geom_t g_cache_destroy_geom;

static g_taste_t g_cache_taste;
static g_ctl_req_t g_cache_config;
static g_dumpconf_t g_cache_dumpconf;

struct g_class g_cache_class = {
        .name = G_CACHE_CLASS_NAME,
        .version = G_VERSION,
        .ctlreq = g_cache_config,
        .taste = g_cache_taste,
        .destroy_geom = g_cache_destroy_geom
};

#define OFF2BNO(off, sc)        ((off) >> (sc)->sc_bshift)
#define BNO2OFF(bno, sc)        ((bno) << (sc)->sc_bshift)

static struct g_cache_desc *
g_cache_alloc(struct g_cache_softc *sc)
{
        struct g_cache_desc *dp;

        mtx_assert(&sc->sc_mtx, MA_OWNED);

        if (!TAILQ_EMPTY(&sc->sc_usedlist)) {
                dp = TAILQ_FIRST(&sc->sc_usedlist);
                TAILQ_REMOVE(&sc->sc_usedlist, dp, d_used);
                sc->sc_nused--;
                dp->d_flags = 0;
                LIST_REMOVE(dp, d_next);
                return (dp);
        }
        if (sc->sc_nent > sc->sc_maxent) {
                sc->sc_cachefull++;
                return (NULL);
        }
        dp = malloc(sizeof(*dp), M_GCACHE, M_NOWAIT | M_ZERO);
        if (dp == NULL)
                return (NULL);
        dp->d_data = uma_zalloc(sc->sc_zone, M_NOWAIT);
        if (dp->d_data == NULL) {
                free(dp, M_GCACHE);
                return (NULL);
        }
        sc->sc_nent++;
        return (dp);
}

static void
g_cache_free(struct g_cache_softc *sc, struct g_cache_desc *dp)
{

        mtx_assert(&sc->sc_mtx, MA_OWNED);

        uma_zfree(sc->sc_zone, dp->d_data);
        free(dp, M_GCACHE);
        sc->sc_nent--;
}

static void
g_cache_free_used(struct g_cache_softc *sc)
{
        struct g_cache_desc *dp;
        u_int n;

        mtx_assert(&sc->sc_mtx, MA_OWNED);

        n = g_cache_used_lo * sc->sc_maxent / 100;
        while (sc->sc_nused > n) {
                KASSERT(!TAILQ_EMPTY(&sc->sc_usedlist), ("used list empty"));
                dp = TAILQ_FIRST(&sc->sc_usedlist);
                TAILQ_REMOVE(&sc->sc_usedlist, dp, d_used);
                sc->sc_nused--;
                LIST_REMOVE(dp, d_next);
                g_cache_free(sc, dp);
        }
}

static void
g_cache_deliver(struct g_cache_softc *sc, struct bio *bp,
    struct g_cache_desc *dp, int error)
{
        off_t off1, off, len;

        mtx_assert(&sc->sc_mtx, MA_OWNED);
        KASSERT(OFF2BNO(bp->bio_offset, sc) <= dp->d_bno, ("wrong entry"));
        KASSERT(OFF2BNO(bp->bio_offset + bp->bio_length - 1, sc) >=
            dp->d_bno, ("wrong entry"));

        off1 = BNO2OFF(dp->d_bno, sc);
        off = MAX(bp->bio_offset, off1);
        len = MIN(bp->bio_offset + bp->bio_length, off1 + sc->sc_bsize) - off;

        if (bp->bio_error == 0)
                bp->bio_error = error;
        if (bp->bio_error == 0) {
                bcopy(dp->d_data + (off - off1),
                    bp->bio_data + (off - bp->bio_offset), len);
        }
        bp->bio_completed += len;
        KASSERT(bp->bio_completed <= bp->bio_length, ("extra data"));
        if (bp->bio_completed == bp->bio_length) {
                if (bp->bio_error != 0)
                        bp->bio_completed = 0;
                g_io_deliver(bp, bp->bio_error);
        }

        if (dp->d_flags & D_FLAG_USED) {
                TAILQ_REMOVE(&sc->sc_usedlist, dp, d_used);
                TAILQ_INSERT_TAIL(&sc->sc_usedlist, dp, d_used);
        } else if (OFF2BNO(off + len, sc) > dp->d_bno) {
                TAILQ_INSERT_TAIL(&sc->sc_usedlist, dp, d_used);
                sc->sc_nused++;
                dp->d_flags |= D_FLAG_USED;
        }
        dp->d_atime = time_uptime;
}

static void
g_cache_done(struct bio *bp)
{
        struct g_cache_softc *sc;
        struct g_cache_desc *dp;
        struct bio *bp2, *tmpbp;

        sc = bp->bio_from->geom->softc;
        KASSERT(G_CACHE_DESC1(bp) == sc, ("corrupt bio_caller in g_cache_done()"));
        dp = G_CACHE_DESC2(bp);
        mtx_lock(&sc->sc_mtx);
        bp2 = dp->d_biolist;
        while (bp2 != NULL) {
                KASSERT(G_CACHE_NEXT_BIO1(bp2) == sc, ("corrupt bio_driver in g_cache_done()"));
                tmpbp = G_CACHE_NEXT_BIO2(bp2);
                g_cache_deliver(sc, bp2, dp, bp->bio_error);
                bp2 = tmpbp;
        }
        dp->d_biolist = NULL;
        if (dp->d_flags & D_FLAG_INVALID) {
                sc->sc_invalid--;
                g_cache_free(sc, dp);
        } else if (bp->bio_error) {
                LIST_REMOVE(dp, d_next);
                if (dp->d_flags & D_FLAG_USED) {
                        TAILQ_REMOVE(&sc->sc_usedlist, dp, d_used);
                        sc->sc_nused--;
                }
                g_cache_free(sc, dp);
        }
        mtx_unlock(&sc->sc_mtx);
        g_destroy_bio(bp);
}

static struct g_cache_desc *
g_cache_lookup(struct g_cache_softc *sc, off_t bno)
{
        struct g_cache_desc *dp;

        mtx_assert(&sc->sc_mtx, MA_OWNED);

        LIST_FOREACH(dp, &sc->sc_desclist[G_CACHE_BUCKET(bno)], d_next)
                if (dp->d_bno == bno)
                        return (dp);
        return (NULL);
}

static int
g_cache_read(struct g_cache_softc *sc, struct bio *bp)
{
        struct bio *cbp;
        struct g_cache_desc *dp;

        mtx_lock(&sc->sc_mtx);
        dp = g_cache_lookup(sc,
            OFF2BNO(bp->bio_offset + bp->bio_completed, sc));
        if (dp != NULL) {
                /* Add to waiters list or deliver. */
                sc->sc_cachehits++;
                if (dp->d_biolist != NULL) {
                        G_CACHE_NEXT_BIO1(bp) = sc;
                        G_CACHE_NEXT_BIO2(bp) = dp->d_biolist;
                        dp->d_biolist = bp;
                } else
                        g_cache_deliver(sc, bp, dp, 0);
                mtx_unlock(&sc->sc_mtx);
                return (0);
        }

        /* Cache miss.  Allocate entry and schedule bio.  */
        sc->sc_cachemisses++;
        dp = g_cache_alloc(sc);
        if (dp == NULL) {
                mtx_unlock(&sc->sc_mtx);
                return (ENOMEM);
        }
        cbp = g_clone_bio(bp);
        if (cbp == NULL) {
                g_cache_free(sc, dp);
                mtx_unlock(&sc->sc_mtx);
                return (ENOMEM);
        }

        dp->d_bno = OFF2BNO(bp->bio_offset + bp->bio_completed, sc);
        G_CACHE_NEXT_BIO1(bp) = sc;
        G_CACHE_NEXT_BIO2(bp) = NULL;
        dp->d_biolist = bp;
        LIST_INSERT_HEAD(&sc->sc_desclist[G_CACHE_BUCKET(dp->d_bno)],
            dp, d_next);
        mtx_unlock(&sc->sc_mtx);

        G_CACHE_DESC1(cbp) = sc;
        G_CACHE_DESC2(cbp) = dp;
        cbp->bio_done = g_cache_done;
        cbp->bio_offset = BNO2OFF(dp->d_bno, sc);
        cbp->bio_data = dp->d_data;
        cbp->bio_length = sc->sc_bsize;
        g_io_request(cbp, LIST_FIRST(&bp->bio_to->geom->consumer));
        return (0);
}

static void
g_cache_invalidate(struct g_cache_softc *sc, struct bio *bp)
{
        struct g_cache_desc *dp;
        off_t bno, lim;

        mtx_lock(&sc->sc_mtx);
        bno = OFF2BNO(bp->bio_offset, sc);
        lim = OFF2BNO(bp->bio_offset + bp->bio_length - 1, sc);
        do {
                if ((dp = g_cache_lookup(sc, bno)) != NULL) {
                        LIST_REMOVE(dp, d_next);
                        if (dp->d_flags & D_FLAG_USED) {
                                TAILQ_REMOVE(&sc->sc_usedlist, dp, d_used);
                                sc->sc_nused--;
                        }
                        if (dp->d_biolist == NULL)
                                g_cache_free(sc, dp);
                        else {
                                dp->d_flags = D_FLAG_INVALID;
                                sc->sc_invalid++;
                        }
                }
                bno++;
        } while (bno <= lim);
        mtx_unlock(&sc->sc_mtx);
}

static void
g_cache_start(struct bio *bp)
{
        struct g_cache_softc *sc;
        struct g_geom *gp;
        struct g_cache_desc *dp;
        struct bio *cbp;

        gp = bp->bio_to->geom;
        sc = gp->softc;
        G_CACHE_LOGREQ(bp, "Request received.");
        switch (bp->bio_cmd) {
        case BIO_READ:
                sc->sc_reads++;
                sc->sc_readbytes += bp->bio_length;
                if (!g_cache_enable)
                        break;
                if (bp->bio_offset + bp->bio_length > sc->sc_tail)
                        break;
                if (OFF2BNO(bp->bio_offset, sc) ==
                    OFF2BNO(bp->bio_offset + bp->bio_length - 1, sc)) {
                        sc->sc_cachereads++;
                        sc->sc_cachereadbytes += bp->bio_length;
                        if (g_cache_read(sc, bp) == 0)
                                return;
                        sc->sc_cachereads--;
                        sc->sc_cachereadbytes -= bp->bio_length;
                        break;
                } else if (OFF2BNO(bp->bio_offset, sc) + 1 ==
                    OFF2BNO(bp->bio_offset + bp->bio_length - 1, sc)) {
                        mtx_lock(&sc->sc_mtx);
                        dp = g_cache_lookup(sc, OFF2BNO(bp->bio_offset, sc));
                        if (dp == NULL || dp->d_biolist != NULL) {
                                mtx_unlock(&sc->sc_mtx);
                                break;
                        }
                        sc->sc_cachereads++;
                        sc->sc_cachereadbytes += bp->bio_length;
                        g_cache_deliver(sc, bp, dp, 0);
                        mtx_unlock(&sc->sc_mtx);
                        if (g_cache_read(sc, bp) == 0)
                                return;
                        sc->sc_cachereads--;
                        sc->sc_cachereadbytes -= bp->bio_length;
                        break;
                }
                break;
        case BIO_WRITE:
                sc->sc_writes++;
                sc->sc_wrotebytes += bp->bio_length;
                g_cache_invalidate(sc, bp);
                break;
        }
        cbp = g_clone_bio(bp);
        if (cbp == NULL) {
                g_io_deliver(bp, ENOMEM);
                return;
        }
        cbp->bio_done = g_std_done;
        G_CACHE_LOGREQ(cbp, "Sending request.");
        g_io_request(cbp, LIST_FIRST(&gp->consumer));
}

static void
g_cache_go(void *arg)
{
        struct g_cache_softc *sc = arg;
        struct g_cache_desc *dp;
        int i;

        mtx_assert(&sc->sc_mtx, MA_OWNED);

        /* Forcibly mark idle ready entries as used. */
        for (i = 0; i < G_CACHE_BUCKETS; i++) {
                LIST_FOREACH(dp, &sc->sc_desclist[i], d_next) {
                        if (dp->d_flags & D_FLAG_USED ||
                            dp->d_biolist != NULL ||
                            time_uptime - dp->d_atime < g_cache_idletime)
                                continue;
                        TAILQ_INSERT_TAIL(&sc->sc_usedlist, dp, d_used);
                        sc->sc_nused++;
                        dp->d_flags |= D_FLAG_USED;
                }
        }

        /* Keep the number of used entries low. */
        if (sc->sc_nused > g_cache_used_hi * sc->sc_maxent / 100)
                g_cache_free_used(sc);

        callout_reset(&sc->sc_callout, g_cache_timeout * hz, g_cache_go, sc);
}

static int
g_cache_access(struct g_provider *pp, int dr, int dw, int de)
{
        struct g_geom *gp;
        struct g_consumer *cp;
        int error;

        gp = pp->geom;
        cp = LIST_FIRST(&gp->consumer);
        error = g_access(cp, dr, dw, de);

        return (error);
}

static void
g_cache_orphan(struct g_consumer *cp)
{

        g_topology_assert();
        g_cache_destroy(cp->geom->softc, 1);
}

static struct g_cache_softc *
g_cache_find_device(struct g_class *mp, const char *name)
{
        struct g_geom *gp;

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

static struct g_geom *
g_cache_create(struct g_class *mp, struct g_provider *pp,
    const struct g_cache_metadata *md, u_int type)
{
        struct g_cache_softc *sc;
        struct g_geom *gp;
        struct g_provider *newpp;
        struct g_consumer *cp;
        u_int bshift;
        int i;

        g_topology_assert();

        gp = NULL;
        newpp = NULL;
        cp = NULL;

        G_CACHE_DEBUG(1, "Creating device %s.", md->md_name);

        /* Cache size is minimum 100. */
        if (md->md_size < 100) {
                G_CACHE_DEBUG(0, "Invalid size for device %s.", md->md_name);
                return (NULL);
        }

        /* Block size restrictions. */
        bshift = ffs(md->md_bsize) - 1;
        if (md->md_bsize == 0 || md->md_bsize > maxphys ||
            md->md_bsize != 1 << bshift ||
            (md->md_bsize % pp->sectorsize) != 0) {
                G_CACHE_DEBUG(0, "Invalid blocksize for provider %s.", pp->name);
                return (NULL);
        }

        /* Check for duplicate unit. */
        if (g_cache_find_device(mp, (const char *)&md->md_name) != NULL) {
                G_CACHE_DEBUG(0, "Provider %s already exists.", md->md_name);
                return (NULL);
        }

        gp = g_new_geom(mp, md->md_name);
        sc = g_malloc(sizeof(*sc), M_WAITOK | M_ZERO);
        sc->sc_type = type;
        sc->sc_bshift = bshift;
        sc->sc_bsize = 1 << bshift;
        sc->sc_zone = uma_zcreate("gcache", sc->sc_bsize, NULL, NULL, NULL, NULL,
            UMA_ALIGN_PTR, 0);
        mtx_init(&sc->sc_mtx, "GEOM CACHE mutex", NULL, MTX_DEF);
        for (i = 0; i < G_CACHE_BUCKETS; i++)
                LIST_INIT(&sc->sc_desclist[i]);
        TAILQ_INIT(&sc->sc_usedlist);
        sc->sc_maxent = md->md_size;
        callout_init_mtx(&sc->sc_callout, &sc->sc_mtx, 0);
        gp->softc = sc;
        sc->sc_geom = gp;
        gp->start = g_cache_start;
        gp->orphan = g_cache_orphan;
        gp->access = g_cache_access;
        gp->dumpconf = g_cache_dumpconf;

        newpp = g_new_providerf(gp, "cache/%s", gp->name);
        newpp->sectorsize = pp->sectorsize;
        newpp->mediasize = pp->mediasize;
        if (type == G_CACHE_TYPE_AUTOMATIC)
                newpp->mediasize -= pp->sectorsize;
        sc->sc_tail = BNO2OFF(OFF2BNO(newpp->mediasize, sc), sc);

        cp = g_new_consumer(gp);
        if (g_attach(cp, pp) != 0) {
                G_CACHE_DEBUG(0, "Cannot attach to provider %s.", pp->name);
                g_destroy_consumer(cp);
                g_destroy_provider(newpp);
                mtx_destroy(&sc->sc_mtx);
                g_free(sc);
                g_destroy_geom(gp);
                return (NULL);
        }

        g_error_provider(newpp, 0);
        G_CACHE_DEBUG(0, "Device %s created.", gp->name);
        callout_reset(&sc->sc_callout, g_cache_timeout * hz, g_cache_go, sc);
        return (gp);
}

static int
g_cache_destroy(struct g_cache_softc *sc, boolean_t force)
{
        struct g_geom *gp;
        struct g_provider *pp;
        struct g_cache_desc *dp, *dp2;
        int i;

        g_topology_assert();
        if (sc == NULL)
                return (ENXIO);
        gp = sc->sc_geom;
        pp = LIST_FIRST(&gp->provider);
        if (pp != NULL && (pp->acr != 0 || pp->acw != 0 || pp->ace != 0)) {
                if (force) {
                        G_CACHE_DEBUG(0, "Device %s is still open, so it "
                            "can't be definitely removed.", pp->name);
                } else {
                        G_CACHE_DEBUG(1, "Device %s is still open (r%dw%de%d).",
                            pp->name, pp->acr, pp->acw, pp->ace);
                        return (EBUSY);
                }
        } else {
                G_CACHE_DEBUG(0, "Device %s removed.", gp->name);
        }
        callout_drain(&sc->sc_callout);
        mtx_lock(&sc->sc_mtx);
        for (i = 0; i < G_CACHE_BUCKETS; i++) {
                dp = LIST_FIRST(&sc->sc_desclist[i]);
                while (dp != NULL) {
                        dp2 = LIST_NEXT(dp, d_next);
                        g_cache_free(sc, dp);
                        dp = dp2;
                }
        }
        mtx_unlock(&sc->sc_mtx);
        mtx_destroy(&sc->sc_mtx);
        uma_zdestroy(sc->sc_zone);
        g_free(sc);
        gp->softc = NULL;
        g_wither_geom(gp, ENXIO);

        return (0);
}

static int
g_cache_destroy_geom(struct gctl_req *req, struct g_class *mp, struct g_geom *gp)
{

        return (g_cache_destroy(gp->softc, 0));
}

static int
g_cache_read_metadata(struct g_consumer *cp, struct g_cache_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. */
        cache_metadata_decode(buf, md);
        g_free(buf);

        return (0);
}

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

        g_topology_assert();

        error = g_access(cp, 0, 1, 0);
        if (error != 0)
                return (error);
        pp = cp->provider;
        buf = malloc((size_t)pp->sectorsize, M_GCACHE, M_WAITOK | M_ZERO);
        cache_metadata_encode(md, buf);
        g_topology_unlock();
        error = g_write_data(cp, pp->mediasize - pp->sectorsize, buf, pp->sectorsize);
        g_topology_lock();
        g_access(cp, 0, -1, 0);
        free(buf, M_GCACHE);

        return (error);
}

static struct g_geom *
g_cache_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
{
        struct g_cache_metadata md;
        struct g_consumer *cp;
        struct g_geom *gp;
        int error;

        g_trace(G_T_TOPOLOGY, "%s(%s, %s)", __func__, mp->name, pp->name);
        g_topology_assert();

        G_CACHE_DEBUG(3, "Tasting %s.", pp->name);

        gp = g_new_geom(mp, "cache:taste");
        gp->start = g_cache_start;
        gp->orphan = g_cache_orphan;
        gp->access = g_cache_access;
        cp = g_new_consumer(gp);
        cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE;
        error = g_attach(cp, pp);
        if (error == 0) {
                error = g_cache_read_metadata(cp, &md);
                g_detach(cp);
        }
        g_destroy_consumer(cp);
        g_destroy_geom(gp);
        if (error != 0)
                return (NULL);

        if (strcmp(md.md_magic, G_CACHE_MAGIC) != 0)
                return (NULL);
        if (md.md_version > G_CACHE_VERSION) {
                printf("geom_cache.ko module is too old to handle %s.\n",
                    pp->name);
                return (NULL);
        }
        if (md.md_provsize != pp->mediasize)
                return (NULL);

        gp = g_cache_create(mp, pp, &md, G_CACHE_TYPE_AUTOMATIC);
        if (gp == NULL) {
                G_CACHE_DEBUG(0, "Can't create %s.", md.md_name);
                return (NULL);
        }
        return (gp);
}

static void
g_cache_ctl_create(struct gctl_req *req, struct g_class *mp)
{
        struct g_cache_metadata md;
        struct g_provider *pp;
        struct g_geom *gp;
        intmax_t *bsize, *size;
        const char *name;
        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, "Invalid number of arguments.");
                return;
        }

        strlcpy(md.md_magic, G_CACHE_MAGIC, sizeof(md.md_magic));
        md.md_version = G_CACHE_VERSION;
        name = gctl_get_asciiparam(req, "arg0");
        if (name == NULL) {
                gctl_error(req, "No 'arg0' argument");
                return;
        }
        strlcpy(md.md_name, name, sizeof(md.md_name));

        size = gctl_get_paraml(req, "size", sizeof(*size));
        if (size == NULL) {
                gctl_error(req, "No '%s' argument", "size");
                return;
        }
        if ((u_int)*size < 100) {
                gctl_error(req, "Invalid '%s' argument", "size");
                return;
        }
        md.md_size = (u_int)*size;

        bsize = gctl_get_paraml(req, "blocksize", sizeof(*bsize));
        if (bsize == NULL) {
                gctl_error(req, "No '%s' argument", "blocksize");
                return;
        }
        if (*bsize < 0) {
                gctl_error(req, "Invalid '%s' argument", "blocksize");
                return;
        }
        md.md_bsize = (u_int)*bsize;

        /* This field is not important here. */
        md.md_provsize = 0;

        pp = gctl_get_provider(req, "arg1");
        if (pp == NULL)
                return;
        gp = g_cache_create(mp, pp, &md, G_CACHE_TYPE_MANUAL);
        if (gp == NULL) {
                gctl_error(req, "Can't create %s.", md.md_name);
                return;
        }
}

static void
g_cache_ctl_configure(struct gctl_req *req, struct g_class *mp)
{
        struct g_cache_metadata md;
        struct g_cache_softc *sc;
        struct g_consumer *cp;
        intmax_t *bsize, *size;
        const char *name;
        int error, *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 != 1) {
                gctl_error(req, "Missing device.");
                return;
        }

        name = gctl_get_asciiparam(req, "arg0");
        if (name == NULL) {
                gctl_error(req, "No 'arg0' argument");
                return;
        }
        sc = g_cache_find_device(mp, name);
        if (sc == NULL) {
                G_CACHE_DEBUG(1, "Device %s is invalid.", name);
                gctl_error(req, "Device %s is invalid.", name);
                return;
        }

        size = gctl_get_paraml(req, "size", sizeof(*size));
        if (size == NULL) {
                gctl_error(req, "No '%s' argument", "size");
                return;
        }
        if ((u_int)*size != 0 && (u_int)*size < 100) {
                gctl_error(req, "Invalid '%s' argument", "size");
                return;
        }
        if ((u_int)*size != 0)
                sc->sc_maxent = (u_int)*size;

        bsize = gctl_get_paraml(req, "blocksize", sizeof(*bsize));
        if (bsize == NULL) {
                gctl_error(req, "No '%s' argument", "blocksize");
                return;
        }
        if (*bsize < 0) {
                gctl_error(req, "Invalid '%s' argument", "blocksize");
                return;
        }

        if (sc->sc_type != G_CACHE_TYPE_AUTOMATIC)
                return;

        strlcpy(md.md_name, name, sizeof(md.md_name));
        strlcpy(md.md_magic, G_CACHE_MAGIC, sizeof(md.md_magic));
        md.md_version = G_CACHE_VERSION;
        if ((u_int)*size != 0)
                md.md_size = (u_int)*size;
        else
                md.md_size = sc->sc_maxent;
        if ((u_int)*bsize != 0)
                md.md_bsize = (u_int)*bsize;
        else
                md.md_bsize = sc->sc_bsize;
        cp = LIST_FIRST(&sc->sc_geom->consumer);
        md.md_provsize = cp->provider->mediasize;
        error = g_cache_write_metadata(cp, &md);
        if (error == 0)
                G_CACHE_DEBUG(2, "Metadata on %s updated.", cp->provider->name);
        else
                G_CACHE_DEBUG(0, "Cannot update metadata on %s (error=%d).",
                    cp->provider->name, error);
}

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

        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 'force' argument");
                return;
        }

        for (i = 0; i < *nargs; i++) {
                snprintf(param, sizeof(param), "arg%d", i);
                name = gctl_get_asciiparam(req, param);
                if (name == NULL) {
                        gctl_error(req, "No 'arg%d' argument", i);
                        return;
                }
                sc = g_cache_find_device(mp, name);
                if (sc == NULL) {
                        G_CACHE_DEBUG(1, "Device %s is invalid.", name);
                        gctl_error(req, "Device %s is invalid.", name);
                        return;
                }
                error = g_cache_destroy(sc, *force);
                if (error != 0) {
                        gctl_error(req, "Cannot destroy device %s (error=%d).",
                            sc->sc_name, error);
                        return;
                }
        }
}

static void
g_cache_ctl_reset(struct gctl_req *req, struct g_class *mp)
{
        struct g_cache_softc *sc;
        const char *name;
        char param[16];
        int i, *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 <= 0) {
                gctl_error(req, "Missing device(s).");
                return;
        }

        for (i = 0; i < *nargs; i++) {
                snprintf(param, sizeof(param), "arg%d", i);
                name = gctl_get_asciiparam(req, param);
                if (name == NULL) {
                        gctl_error(req, "No 'arg%d' argument", i);
                        return;
                }
                sc = g_cache_find_device(mp, name);
                if (sc == NULL) {
                        G_CACHE_DEBUG(1, "Device %s is invalid.", name);
                        gctl_error(req, "Device %s is invalid.", name);
                        return;
                }
                sc->sc_reads = 0;
                sc->sc_readbytes = 0;
                sc->sc_cachereads = 0;
                sc->sc_cachereadbytes = 0;
                sc->sc_cachehits = 0;
                sc->sc_cachemisses = 0;
                sc->sc_cachefull = 0;
                sc->sc_writes = 0;
                sc->sc_wrotebytes = 0;
        }
}

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

        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_CACHE_VERSION) {
                gctl_error(req, "Userland and kernel parts are out of sync.");
                return;
        }

        if (strcmp(verb, "create") == 0) {
                g_cache_ctl_create(req, mp);
                return;
        } else if (strcmp(verb, "configure") == 0) {
                g_cache_ctl_configure(req, mp);
                return;
        } else if (strcmp(verb, "destroy") == 0 ||
            strcmp(verb, "stop") == 0) {
                g_cache_ctl_destroy(req, mp);
                return;
        } else if (strcmp(verb, "reset") == 0) {
                g_cache_ctl_reset(req, mp);
                return;
        }

        gctl_error(req, "Unknown verb.");
}

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

        if (pp != NULL || cp != NULL)
                return;
        sc = gp->softc;
        sbuf_printf(sb, "%s<Size>%u</Size>\n", indent, sc->sc_maxent);
        sbuf_printf(sb, "%s<BlockSize>%u</BlockSize>\n", indent, sc->sc_bsize);
        sbuf_printf(sb, "%s<TailOffset>%ju</TailOffset>\n", indent,
            (uintmax_t)sc->sc_tail);
        sbuf_printf(sb, "%s<Entries>%u</Entries>\n", indent, sc->sc_nent);
        sbuf_printf(sb, "%s<UsedEntries>%u</UsedEntries>\n", indent,
            sc->sc_nused);
        sbuf_printf(sb, "%s<InvalidEntries>%u</InvalidEntries>\n", indent,
            sc->sc_invalid);
        sbuf_printf(sb, "%s<Reads>%ju</Reads>\n", indent, sc->sc_reads);
        sbuf_printf(sb, "%s<ReadBytes>%ju</ReadBytes>\n", indent,
            sc->sc_readbytes);
        sbuf_printf(sb, "%s<CacheReads>%ju</CacheReads>\n", indent,
            sc->sc_cachereads);
        sbuf_printf(sb, "%s<CacheReadBytes>%ju</CacheReadBytes>\n", indent,
            sc->sc_cachereadbytes);
        sbuf_printf(sb, "%s<CacheHits>%ju</CacheHits>\n", indent,
            sc->sc_cachehits);
        sbuf_printf(sb, "%s<CacheMisses>%ju</CacheMisses>\n", indent,
            sc->sc_cachemisses);
        sbuf_printf(sb, "%s<CacheFull>%ju</CacheFull>\n", indent,
            sc->sc_cachefull);
        sbuf_printf(sb, "%s<Writes>%ju</Writes>\n", indent, sc->sc_writes);
        sbuf_printf(sb, "%s<WroteBytes>%ju</WroteBytes>\n", indent,
            sc->sc_wrotebytes);
}

DECLARE_GEOM_CLASS(g_cache_class, g_cache);
MODULE_VERSION(geom_cache, 0);