modules/zfs/zfs.c

	zfs.c revision ea8dc4b6d2251b437950c0056bc626b311c73c27
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <mdb/mdb_ctf.h>
#include <sys/zfs_context.h>
#include <sys/mdb_modapi.h>
#include <sys/dbuf.h>
#include <sys/dmu_objset.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_pool.h>
#include <sys/metaslab_impl.h>
#include <sys/space_map.h>
#include <sys/list.h>
#include <sys/spa_impl.h>
#include <sys/vdev_impl.h>
#include <sys/zio_compress.h>

#ifndef _KERNEL
#include "../genunix/list.h"
#endif

#ifdef _KERNEL
#define ZFS_OBJ_NAME    "zfs"
#else
#define ZFS_OBJ_NAME    "libzpool.so.1"
#endif

static char *
local_strdup(const char *s)
{
    char *s1 = mdb_alloc(strlen(s) + 1, UM_SLEEP);

    (void) strcpy(s1, s);
    return (s1);
}

static int
getmember(uintptr_t addr, const char *type, mdb_ctf_id_t *idp,
    const char *member, int len, void *buf)
{
    mdb_ctf_id_t id;
    ulong_t off;
    char name[64];

    if (idp == NULL) {
        if (mdb_ctf_lookup_by_name(type, &id) == -1) {
            mdb_warn("couldn't find type %s", type);
            return (DCMD_ERR);
        }
        idp = &id;
    } else {
        type = name;
        mdb_ctf_type_name(*idp, name, sizeof (name));
    }

    if (mdb_ctf_offsetof(*idp, member, &off) == -1) {
        mdb_warn("couldn't find member %s of type %s\n", member, type);
        return (DCMD_ERR);
    }
    if (off % 8 != 0) {
        mdb_warn("member %s of type %s is unsupported bitfield",
            member, type);
        return (DCMD_ERR);
    }
    off /= 8;

    if (mdb_vread(buf, len, addr + off) == -1) {
        mdb_warn("failed to read %s from %s at %p",
            member, type, addr + off);
        return (DCMD_ERR);
    }
    /* mdb_warn("read %s from %s at %p+%llx\n", member, type, addr, off); */

    return (0);
}

#define GETMEMB(addr, type, member, dest) \
    getmember(addr, #type, NULL, #member, sizeof (dest), &(dest))

#define GETMEMBID(addr, ctfid, member, dest) \
    getmember(addr, NULL, ctfid, #member, sizeof (dest), &(dest))

static int
getrefcount(uintptr_t addr, mdb_ctf_id_t *id,
    const char *member, uint64_t *rc)
{
    static int gotid;
    static mdb_ctf_id_t rc_id;
    ulong_t off;

    if (!gotid) {
        if (mdb_ctf_lookup_by_name("struct refcount", &rc_id) == -1) {
            mdb_warn("couldn't find struct refcount");
            return (DCMD_ERR);
        }
        gotid = TRUE;
    }

    if (mdb_ctf_offsetof(*id, member, &off) == -1) {
        char name[64];
        mdb_ctf_type_name(*id, name, sizeof (name));
        mdb_warn("couldn't find member %s of type %s\n", member, name);
        return (DCMD_ERR);
    }
    off /= 8;

    return (GETMEMBID(addr + off, &rc_id, rc_count, *rc));
}

static int
read_symbol(char *sym_name, void **bufp)
{
    GElf_Sym sym;

    if (mdb_lookup_by_obj(MDB_TGT_OBJ_EVERY, sym_name, &sym)) {
        mdb_warn("can't find symbol %s", sym_name);
        return (DCMD_ERR);
    }

    *bufp = mdb_alloc(sym.st_size, UM_SLEEP);

    if (mdb_vread(*bufp, sym.st_size, sym.st_value) == -1) {
        mdb_warn("can't read data for symbol %s", sym_name);
        mdb_free(*bufp, sym.st_size);
        return (DCMD_ERR);
    }

    return (DCMD_OK);
}

static int verbose;

static int
freelist_walk_init(mdb_walk_state_t *wsp)
{
    if (wsp->walk_addr == NULL) {
        mdb_warn("must supply starting address\n");
        return (WALK_ERR);
    }

    wsp->walk_data = 0;  /* Index into the freelist */
    return (WALK_NEXT);
}

static int
freelist_walk_step(mdb_walk_state_t *wsp)
{
    uint64_t entry;
    uintptr_t number = (uintptr_t)wsp->walk_data;
    char *ddata[] = { "ALLOC", "FREE", "CONDENSE", "INVALID" };
    int mapshift = SPA_MINBLOCKSHIFT;

    if (mdb_vread(&entry, sizeof (entry), wsp->walk_addr) == -1) {
        mdb_warn("failed to read freelist entry %p", wsp->walk_addr);
        return (WALK_DONE);
    }
    wsp->walk_addr += sizeof (entry);
    wsp->walk_data = (void *)(number + 1);

    if (SM_DEBUG_DECODE(entry)) {
        mdb_printf("DEBUG: %3u  %10s: txg=%llu  pass=%llu\n",
            number,
            ddata[SM_DEBUG_ACTION_DECODE(entry)],
            SM_DEBUG_TXG_DECODE(entry),
            SM_DEBUG_SYNCPASS_DECODE(entry));
    } else {
        mdb_printf("Entry: %3u  offsets=%08llx-%08llx  type=%c  "
            "size=%06llx", number,
            SM_OFFSET_DECODE(entry) << mapshift,
            (SM_OFFSET_DECODE(entry) + SM_RUN_DECODE(entry)) <<
            mapshift,
            SM_TYPE_DECODE(entry) == SM_ALLOC ? 'A' : 'F',
            SM_RUN_DECODE(entry) << mapshift);
        if (verbose)
            mdb_printf("      (raw=%012llx)\n", entry);
        mdb_printf("\n");
    }
    return (WALK_NEXT);
}

/* ARGSUSED */
static void
freelist_walk_fini(mdb_walk_state_t *wsp)
{
}

typedef struct dbuf_walk_data {
    dbuf_hash_table_t ht;
    int64_t bucket;
    uintptr_t dbp;
    dmu_buf_impl_t db;
} dbuf_walk_data_t;

static int
dbuf_walk_init(mdb_walk_state_t *wsp)
{
    dbuf_walk_data_t *dwd;

    if (wsp->walk_addr != NULL) {
        mdb_warn("must supply starting address\n");
        return (WALK_ERR);
    }

    dwd = mdb_alloc(sizeof (dbuf_walk_data_t), UM_SLEEP);

    if (mdb_readvar(&dwd->ht, "dbuf_hash_table") == -1) {
        mdb_warn("failed to read 'dbuf_hash_table'");
        mdb_free(dwd, sizeof (dbuf_walk_data_t));
        return (WALK_ERR);
    }
    dwd->bucket = -1;
    dwd->dbp = 0;
    wsp->walk_data = dwd;
    return (WALK_NEXT);
}

static int
dbuf_walk_step(mdb_walk_state_t *wsp)
{
    int status;
    dbuf_walk_data_t *dwd = wsp->walk_data;

    while (dwd->dbp == 0) {
        dwd->bucket++;
        if (dwd->bucket == dwd->ht.hash_table_mask+1)
            return (WALK_DONE);

        if (mdb_vread(&dwd->dbp, sizeof (void *),
            (uintptr_t)(dwd->ht.hash_table+dwd->bucket)) == -1) {
            mdb_warn("failed to read hash bucket %u at %p",
                dwd->bucket, dwd->ht.hash_table+dwd->bucket);
            return (WALK_DONE);
        }
    }

    wsp->walk_addr = dwd->dbp;
    if (mdb_vread(&dwd->db, sizeof (dmu_buf_impl_t),
        wsp->walk_addr) == -1) {
        mdb_warn("failed to read dbuf at %p", wsp->walk_addr);
        return (WALK_DONE);
    }
    status = wsp->walk_callback(wsp->walk_addr, &dwd->db, wsp->walk_cbdata);

    dwd->dbp = (uintptr_t)dwd->db.db_hash_next;
    return (status);
}

static void
dbuf_walk_fini(mdb_walk_state_t *wsp)
{
    dbuf_walk_data_t *dwd = wsp->walk_data;
    mdb_free(dwd, sizeof (dbuf_walk_data_t));
}

static int
dataset_name(uintptr_t addr, char *buf)
{
    static int gotid;
    static mdb_ctf_id_t dd_id;
    uintptr_t dd_parent;
    char dd_myname[MAXNAMELEN];

    if (!gotid) {
        if (mdb_ctf_lookup_by_name("struct dsl_dir",
            &dd_id) == -1) {
            mdb_warn("couldn't find struct dsl_dir");
            return (DCMD_ERR);
        }
        gotid = TRUE;
    }
    if (GETMEMBID(addr, &dd_id, dd_parent, dd_parent) ||
        GETMEMBID(addr, &dd_id, dd_myname, dd_myname)) {
        return (DCMD_ERR);
    }

    if (dd_parent) {
        if (dataset_name(dd_parent, buf))
            return (DCMD_ERR);
        strcat(buf, "/");
    }

    if (dd_myname[0])
        strcat(buf, dd_myname);
    else
        strcat(buf, "???");

    return (0);
}

static int
objset_name(uintptr_t addr, char *buf)
{
    static int gotid;
    static mdb_ctf_id_t osi_id, ds_id;
    uintptr_t os_dsl_dataset;
    char ds_snapname[MAXNAMELEN];
    uintptr_t ds_dir;

    buf[0] = '\0';

    if (!gotid) {
        if (mdb_ctf_lookup_by_name("struct objset_impl",
            &osi_id) == -1) {
            mdb_warn("couldn't find struct objset_impl");
            return (DCMD_ERR);
        }
        if (mdb_ctf_lookup_by_name("struct dsl_dataset",
            &ds_id) == -1) {
            mdb_warn("couldn't find struct dsl_dataset");
            return (DCMD_ERR);
        }

        gotid = TRUE;
    }

    if (GETMEMBID(addr, &osi_id, os_dsl_dataset, os_dsl_dataset))
        return (DCMD_ERR);

    if (os_dsl_dataset == 0) {
        strcat(buf, "mos");
        return (0);
    }

    if (GETMEMBID(os_dsl_dataset, &ds_id, ds_snapname, ds_snapname) ||
        GETMEMBID(os_dsl_dataset, &ds_id, ds_dir, ds_dir)) {
        return (DCMD_ERR);
    }

    if (ds_dir && dataset_name(ds_dir, buf))
        return (DCMD_ERR);

    if (ds_snapname[0]) {
        strcat(buf, "@");
        strcat(buf, ds_snapname);
    }
    return (0);
}

static void
enum_lookup(char *out, size_t size, mdb_ctf_id_t id, int val,
    const char *prefix)
{
    const char *cp;
    size_t len = strlen(prefix);

    if ((cp = mdb_ctf_enum_name(id, val)) != NULL) {
        if (strncmp(cp, prefix, len) == 0)
            cp += len;
        (void) strncpy(out, cp, size);
    } else {
        mdb_snprintf(out, size, "? (%d)", val);
    }
}

/* ARGSUSED */
static int
zio_pipeline(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
    mdb_ctf_id_t pipe_enum;
    int i;
    char stage[1024];

    if (mdb_ctf_lookup_by_name("enum zio_stage", &pipe_enum) == -1) {
        mdb_warn("Could not find enum zio_stage");
        return (DCMD_ERR);
    }

    for (i = 0; i < 32; i++) {
        if (addr & (1U << i)) {
            enum_lookup(stage, sizeof (stage), pipe_enum, i,
                "ZIO_STAGE_");
            mdb_printf("    %s\n", stage);
        }
    }

    return (DCMD_OK);
}

/* ARGSUSED */
static int
blkptr(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
    blkptr_t bp;
    dva_t *dva;
    dmu_object_type_info_t *doti;
    zio_compress_info_t *zct;
    zio_checksum_info_t *zci;
    int i;
    char buf[MAXPATHLEN];

    if (mdb_vread(&bp, sizeof (blkptr_t), addr) == -1) {
        mdb_warn("failed to read blkptr_t");
        return (DCMD_ERR);
    }

    if (read_symbol("dmu_ot", (void **)&doti) != DCMD_OK)
        return (DCMD_ERR);
    for (i = 0; i < DMU_OT_NUMTYPES; i++) {
        mdb_readstr(buf, sizeof (buf), (uintptr_t)doti[i].ot_name);
        doti[i].ot_name = local_strdup(buf);
    }

    if (read_symbol("zio_checksum_table", (void **)&zci) != DCMD_OK)
        return (DCMD_ERR);
    for (i = 0; i < ZIO_CHECKSUM_FUNCTIONS; i++) {
        mdb_readstr(buf, sizeof (buf), (uintptr_t)zci[i].ci_name);
        zci[i].ci_name = local_strdup(buf);
    }

    if (read_symbol("zio_compress_table", (void **)&zct) != DCMD_OK)
        return (DCMD_ERR);
    for (i = 0; i < ZIO_COMPRESS_FUNCTIONS; i++) {
        mdb_readstr(buf, sizeof (buf), (uintptr_t)zct[i].ci_name);
        zct[i].ci_name = local_strdup(buf);
    }

    for (i = 0; i < SPA_DVAS_PER_BP; i++) {
        dva = &bp.blk_dva[i];
        mdb_printf("DVA[%d]: vdev_id %lld / %llx\n", i,
            DVA_GET_VDEV(dva), DVA_GET_OFFSET(dva));
        mdb_printf("DVA[%d]:                    GRID:  %04x\t"
            "ASIZE: %llx\n", i, DVA_GET_GRID(dva), DVA_GET_ASIZE(dva));
    }
    mdb_printf("LSIZE:  %-16llx\t\tPSIZE: %llx\n",
        BP_GET_LSIZE(&bp), BP_GET_PSIZE(&bp));
    mdb_printf("ENDIAN: %6s             GANG:  %-5s\tTYPE:  %s\n",
        BP_GET_BYTEORDER(&bp) ? "LITTLE" : "BIG",
        DVA_GET_GANG(dva) ? "TRUE" : "FALSE",
        doti[BP_GET_TYPE(&bp)].ot_name);
    mdb_printf("BIRTH:  %-16llx   LEVEL: %-2d\tFILL:  %llx\n",
        bp.blk_birth, BP_GET_LEVEL(&bp), bp.blk_fill);
    mdb_printf("CKFUNC: %-16s\t\tCOMP:  %s\n",
        zci[BP_GET_CHECKSUM(&bp)].ci_name,
        zct[BP_GET_COMPRESS(&bp)].ci_name);
    mdb_printf("CKSUM:  %llx:%llx:%llx:%llx\n",
        bp.blk_cksum.zc_word[0],
        bp.blk_cksum.zc_word[1],
        bp.blk_cksum.zc_word[2],
        bp.blk_cksum.zc_word[3]);

    return (DCMD_OK);
}

/* ARGSUSED */
static int
dbuf(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
    mdb_ctf_id_t id;
    dmu_buf_t db;
    uintptr_t objset;
    uint8_t level;
    uint64_t blkid;
    uint64_t holds;
    char objectname[32];
    char blkidname[32];
    char path[MAXNAMELEN];

    if (DCMD_HDRSPEC(flags)) {
        mdb_printf("        addr object lvl blkid holds os\n");
    }

    if (mdb_ctf_lookup_by_name("struct dmu_buf_impl", &id) == -1) {
        mdb_warn("couldn't find struct dmu_buf_impl_t");
        return (DCMD_ERR);
    }

    if (GETMEMBID(addr, &id, db_objset, objset) ||
        GETMEMBID(addr, &id, db, db) ||
        GETMEMBID(addr, &id, db_level, level) ||
        GETMEMBID(addr, &id, db_blkid, blkid)) {
        return (WALK_ERR);
    }

    if (getrefcount(addr, &id, "db_holds", &holds)) {
        return (WALK_ERR);
    }

    if (db.db_object == DMU_META_DNODE_OBJECT)
        (void) strcpy(objectname, "mdn");
    else
        (void) mdb_snprintf(objectname, sizeof (objectname), "%llx",
            (u_longlong_t)db.db_object);

    if (blkid == DB_BONUS_BLKID)
        (void) strcpy(blkidname, "bonus");
    else
        (void) mdb_snprintf(blkidname, sizeof (blkidname), "%llx",
            (u_longlong_t)blkid);

    if (objset_name(objset, path)) {
        return (WALK_ERR);
    }

    mdb_printf("%p %8s %1u %9s %2llu %s\n",
        addr, objectname, level, blkidname, holds, path);

    return (DCMD_OK);
}

/* ARGSUSED */
static int
dbuf_stats(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
#define HISTOSZ 32
    uintptr_t dbp;
    dmu_buf_impl_t db;
    dbuf_hash_table_t ht;
    uint64_t bucket, ndbufs;
    uint64_t histo[HISTOSZ];
    uint64_t histo2[HISTOSZ];
    int i, maxidx;

    if (mdb_readvar(&ht, "dbuf_hash_table") == -1) {
        mdb_warn("failed to read 'dbuf_hash_table'");
        return (DCMD_ERR);
    }

    for (i = 0; i < HISTOSZ; i++) {
        histo[i] = 0;
        histo2[i] = 0;
    }

    ndbufs = 0;
    for (bucket = 0; bucket < ht.hash_table_mask+1; bucket++) {
        int len;

        if (mdb_vread(&dbp, sizeof (void *),
            (uintptr_t)(ht.hash_table+bucket)) == -1) {
            mdb_warn("failed to read hash bucket %u at %p",
                bucket, ht.hash_table+bucket);
            return (DCMD_ERR);
        }

        len = 0;
        while (dbp != 0) {
            if (mdb_vread(&db, sizeof (dmu_buf_impl_t),
                dbp) == -1) {
                mdb_warn("failed to read dbuf at %p", dbp);
                return (DCMD_ERR);
            }
            dbp = (uintptr_t)db.db_hash_next;
            for (i = MIN(len, HISTOSZ - 1); i >= 0; i--)
                histo2[i]++;
            len++;
            ndbufs++;
        }

        if (len >= HISTOSZ)
            len = HISTOSZ-1;
        histo[len]++;
    }

    mdb_printf("hash table has %llu buckets, %llu dbufs "
        "(avg %llu buckets/dbuf)\n",
        ht.hash_table_mask+1, ndbufs,
        (ht.hash_table_mask+1)/ndbufs);

    mdb_printf("\n");
    maxidx = 0;
    for (i = 0; i < HISTOSZ; i++)
        if (histo[i] > 0)
            maxidx = i;
    mdb_printf("hash chain length   number of buckets\n");
    for (i = 0; i <= maxidx; i++)
        mdb_printf("%u          %llu\n", i, histo[i]);

    mdb_printf("\n");
    maxidx = 0;
    for (i = 0; i < HISTOSZ; i++)
        if (histo2[i] > 0)
            maxidx = i;
    mdb_printf("hash chain depth    number of dbufs\n");
    for (i = 0; i <= maxidx; i++)
        mdb_printf("%u or more      %llu    %llu%%\n",
            i, histo2[i], histo2[i]*100/ndbufs);


    return (DCMD_OK);
}

typedef struct dbufs_data {
    mdb_ctf_id_t id;
    uint64_t objset;
    uint64_t object;
    uint64_t level;
    uint64_t blkid;
    char *osname;
} dbufs_data_t;

#define DBUFS_UNSET (0xbaddcafedeadbeefULL)

/* ARGSUSED */
static int
dbufs_cb(uintptr_t addr, const void *unknown, void *arg)
{
    dbufs_data_t *data = arg;
    uintptr_t objset;
    dmu_buf_t db;
    uint8_t level;
    uint64_t blkid;
    char osname[MAXNAMELEN];

    if (GETMEMBID(addr, &data->id, db_objset, objset) ||
        GETMEMBID(addr, &data->id, db, db) ||
        GETMEMBID(addr, &data->id, db_level, level) ||
        GETMEMBID(addr, &data->id, db_blkid, blkid)) {
        return (WALK_ERR);
    }

    if ((data->objset == DBUFS_UNSET || data->objset == objset) &&
        (data->osname == NULL || (objset_name(objset, osname) == 0 &&
        strcmp(data->osname, osname) == 0)) &&
        (data->object == DBUFS_UNSET || data->object == db.db_object) &&
        (data->level == DBUFS_UNSET || data->level == level) &&
        (data->blkid == DBUFS_UNSET || data->blkid == blkid)) {
        mdb_printf("%#lr\n", addr);
    }
    return (WALK_NEXT);
}

/* ARGSUSED */
static int
dbufs(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
    dbufs_data_t data;
    char *object = NULL;
    char *blkid = NULL;

    data.objset = data.object = data.level = data.blkid = DBUFS_UNSET;
    data.osname = NULL;

    if (mdb_getopts(argc, argv,
        'O', MDB_OPT_UINT64, &data.objset,
        'n', MDB_OPT_STR, &data.osname,
        'o', MDB_OPT_STR, &object,
        'l', MDB_OPT_UINT64, &data.level,
        'b', MDB_OPT_STR, &blkid) != argc) {
        return (DCMD_USAGE);
    }

    if (object) {
        if (strcmp(object, "mdn") == 0) {
            data.object = DMU_META_DNODE_OBJECT;
        } else {
            data.object = mdb_strtoull(object);
        }
    }

    if (blkid) {
        if (strcmp(blkid, "bonus") == 0) {
            data.blkid = DB_BONUS_BLKID;
        } else {
            data.blkid = mdb_strtoull(blkid);
        }
    }

    if (mdb_ctf_lookup_by_name("struct dmu_buf_impl", &data.id) == -1) {
        mdb_warn("couldn't find struct dmu_buf_impl_t");
        return (DCMD_ERR);
    }

    if (mdb_pwalk("dbufs", dbufs_cb, &data, 0) != 0) {
        mdb_warn("can't walk dbufs");
        return (DCMD_ERR);
    }

    return (DCMD_OK);
}

typedef struct abuf_find_data {
    dva_t dva;
    mdb_ctf_id_t id;
} abuf_find_data_t;

/* ARGSUSED */
static int
abuf_find_cb(uintptr_t addr, const void *unknown, void *arg)
{
    abuf_find_data_t *data = arg;
    dva_t dva;

    if (GETMEMBID(addr, &data->id, b_dva, dva)) {
        return (WALK_ERR);
    }

    if (dva.dva_word[0] == data->dva.dva_word[0] &&
        dva.dva_word[1] == data->dva.dva_word[1]) {
        mdb_printf("%#lr\n", addr);
    }
    return (WALK_NEXT);
}

/* ARGSUSED */
static int
abuf_find(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
    abuf_find_data_t data;
    GElf_Sym sym;
    int i;
    const char *syms[] = {
        "ARC_mru_top",
        "ARC_mru_bot",
        "ARC_mfu_top",
        "ARC_mfu_bot",
    };

    if (argc != 2)
        return (DCMD_USAGE);

    for (i = 0; i < 2; i ++) {
        switch (argv[i].a_type) {
        case MDB_TYPE_STRING:
            data.dva.dva_word[i] = mdb_strtoull(argv[i].a_un.a_str);
            break;
        case MDB_TYPE_IMMEDIATE:
            data.dva.dva_word[i] = argv[i].a_un.a_val;
            break;
        default:
            return (DCMD_USAGE);
        }
    }

    if (mdb_ctf_lookup_by_name("struct arc_buf_hdr", &data.id) == -1) {
        mdb_warn("couldn't find struct arc_buf_hdr");
        return (DCMD_ERR);
    }

    for (i = 0; i < sizeof (syms) / sizeof (syms[0]); i++) {
        if (mdb_lookup_by_name(syms[i], &sym)) {
            mdb_warn("can't find symbol %s", syms[i]);
            return (DCMD_ERR);
        }

        if (mdb_pwalk("list", abuf_find_cb, &data, sym.st_value) != 0) {
            mdb_warn("can't walk %s", syms[i]);
            return (DCMD_ERR);
        }
    }

    return (DCMD_OK);
}

void
abuf_help(void)
{
    mdb_printf("::abuf_find dva_word[0] dva_word[1]\n");
}

/*
 * ::spa
 *
 *  -c  Print configuration information as well
 *  -v  Print vdev state
 *  -e  Print vdev error stats
 *
 * Print a summarized spa_t.  When given no arguments, prints out a table of all
 * active pools on the system.
 */
/* ARGSUSED */
static int
spa_print(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
    spa_t spa;
    char poolname[MAXNAMELEN];
    const char *statetab[] = { "ACTIVE", "EXPORTED", "DESTROYED",
        "UNINIT", "UNAVAIL" };
    const char *state;
    int config = FALSE;
    int vdevs = FALSE;
    int errors = FALSE;

    if (mdb_getopts(argc, argv,
        'c', MDB_OPT_SETBITS, TRUE, &config,
        'v', MDB_OPT_SETBITS, TRUE, &vdevs,
        'e', MDB_OPT_SETBITS, TRUE, &errors,
        NULL) != argc)
        return (DCMD_USAGE);

    if (!(flags & DCMD_ADDRSPEC)) {
        if (mdb_walk_dcmd("spa", "spa", argc, argv) == -1) {
            mdb_warn("can't walk spa");
            return (DCMD_ERR);
        }

        return (DCMD_OK);
    }

    if (flags & DCMD_PIPE_OUT) {
        mdb_printf("%#lr\n", addr);
        return (DCMD_OK);
    }

    if (DCMD_HDRSPEC(flags))
        mdb_printf("%<u>%-?s %9s %-*s%</u>\n", "ADDR", "STATE",
            sizeof (uintptr_t) == 4 ? 60 : 52, "NAME");

    if (mdb_vread(&spa, sizeof (spa), addr) == -1) {
        mdb_warn("failed to read spa_t at %p", addr);
        return (DCMD_ERR);
    }

    if (mdb_readstr(poolname, sizeof (poolname), (uintptr_t)spa.spa_name)
        == -1) {
        mdb_warn("failed to read pool name at %p", spa.spa_name);
        return (DCMD_ERR);
    }

    if (spa.spa_state < 0 || spa.spa_state > POOL_STATE_UNAVAIL)
        state = "UNKNOWN";
    else
        state = statetab[spa.spa_state];

    mdb_printf("%0?p %9s %s\n", addr, state, poolname);

    if (config) {
        mdb_printf("\n");
        mdb_inc_indent(4);
        if (mdb_call_dcmd("spa_config", addr, flags, 0,
            NULL) != DCMD_OK)
            return (DCMD_ERR);
        mdb_dec_indent(4);
    }

    if (vdevs || errors) {
        mdb_arg_t v;

        v.a_type = MDB_TYPE_STRING;
        v.a_un.a_str = "-e";

        mdb_printf("\n");
        mdb_inc_indent(4);
        if (mdb_call_dcmd("spa_vdevs", addr, flags, errors ? 1 : 0,
            &v) != DCMD_OK)
            return (DCMD_ERR);
        mdb_dec_indent(4);
    }

    return (DCMD_OK);
}

/*
 * ::spa_config
 *
 * Given a spa_t, print the configuration information stored in spa_config.
 * Since it's just an nvlist, format it as an indented list of name=value pairs.
 * We simply read the value of spa_config and pass off to ::nvlist.
 */
/* ARGSUSED */
static int
spa_print_config(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
    spa_t spa;

    if (argc != 0 || !(flags & DCMD_ADDRSPEC))
        return (DCMD_USAGE);

    if (mdb_vread(&spa, sizeof (spa), addr) == -1) {
        mdb_warn("failed to read spa_t at %p", addr);
        return (DCMD_ERR);
    }

    if (spa.spa_config == NULL) {
        mdb_printf("(none)\n");
        return (DCMD_OK);
    }

    return (mdb_call_dcmd("nvlist", (uintptr_t)spa.spa_config, flags,
        0, NULL));
}

void
vdev_help(void)
{
    mdb_printf("[vdev_t*]::vdev [-qr]\n"
        "\t-> -q display vdev_queue parameters\n"
        "\t-> -r recursive (visit all children)\n");
}

/*
 * ::vdev
 *
 * Print out a summarized vdev_t, in the following form:
 *
 * ADDR             STATE   AUX            DESC
 * fffffffbcde23df0 HEALTHY -              /dev/dsk/c0t0d0
 *
 * or with "-q" to print out a vdev_t's vdev_queue parameters:
 *
 *  vdev_t: c26ae4c0
 *     c26ae73c min pending         0x2
 *     c26ae744 max pending         0x23
 *     c26ae74c agg limit           0x20000
 *     c26ae754 time shift          0x4
 *     c26ae75c ramp rate           0x2
 *
 * If '-r' is specified, recursively visit all children.
 *
 * With '-e', the statistics associated with the vdev are printed as well.
 */
static int
do_print_vdev(uintptr_t addr, int flags, int depth, int queue, int stats,
    int recursive)
{
    vdev_t vdev;
    char desc[MAXNAMELEN];
    int c, children;
    uintptr_t *child;
    const char *state, *aux;

    if (mdb_vread(&vdev, sizeof (vdev), (uintptr_t)addr) == -1) {
        mdb_warn("failed to read vdev_t at %p\n", (uintptr_t)addr);
        return (DCMD_ERR);
    }

    if (flags & DCMD_PIPE_OUT) {
        mdb_printf("%#lr", addr);
    } else {
        if (vdev.vdev_path != NULL) {
            if (mdb_readstr(desc, sizeof (desc),
                (uintptr_t)vdev.vdev_path) == -1) {
                mdb_warn("failed to read vdev_path at %p\n",
                    vdev.vdev_path);
                return (DCMD_ERR);
            }
        } else if (vdev.vdev_ops != NULL) {
            vdev_ops_t ops;
            if (mdb_vread(&ops, sizeof (ops),
                (uintptr_t)vdev.vdev_ops) == -1) {
                mdb_warn("failed to read vdev_ops at %p\n",
                    vdev.vdev_ops);
                return (DCMD_ERR);
            }
            (void) strcpy(desc, ops.vdev_op_type);
        } else {
            (void) strcpy(desc, "<unknown>");
        }

        if (depth == 0 && DCMD_HDRSPEC(flags))
            mdb_printf("%<u>%-?s %-9s %-12s %-*s%</u>\n",
                "ADDR", "STATE", "AUX",
                sizeof (uintptr_t) == 4 ? 43 : 35,
                "DESCRIPTION");

        mdb_printf("%0?p ", addr);

        switch (vdev.vdev_state) {
        case VDEV_STATE_CLOSED:
            state = "CLOSED";
            break;
        case VDEV_STATE_OFFLINE:
            state = "OFFLINE";
            break;
        case VDEV_STATE_CANT_OPEN:
            state = "CANT_OPEN";
            break;
        case VDEV_STATE_DEGRADED:
            state = "DEGRADED";
            break;
        case VDEV_STATE_HEALTHY:
            state = "HEALTHY";
            break;
        default:
            state = "UNKNOWN";
            break;
        }

        switch (vdev.vdev_stat.vs_aux) {
        case VDEV_AUX_NONE:
            aux = "-";
            break;
        case VDEV_AUX_OPEN_FAILED:
            aux = "OPEN_FAILED";
            break;
        case VDEV_AUX_CORRUPT_DATA:
            aux = "CORRUPT_DATA";
            break;
        case VDEV_AUX_NO_REPLICAS:
            aux = "NO_REPLICAS";
            break;
        case VDEV_AUX_BAD_GUID_SUM:
            aux = "BAD_GUID_SUM";
            break;
        case VDEV_AUX_TOO_SMALL:
            aux = "TOO_SMALL";
            break;
        case VDEV_AUX_BAD_LABEL:
            aux = "BAD_LABEL";
            break;
        default:
            aux = "UNKNOWN";
            break;
        }

        mdb_printf("%-9s %-12s %*s%s\n", state, aux, depth, "", desc);

        if (queue) {
            mdb_inc_indent(4);
            mdb_printf("\n");
            mdb_printf("%p min pending      0x%llx\n",
                (uintptr_t)(addr + offsetof(vdev_t,
                vdev_queue.vq_min_pending)),
                vdev.vdev_queue.vq_min_pending);
            mdb_printf("%p max pending      0x%llx\n",
                (uintptr_t)(addr + offsetof(vdev_t,
                vdev_queue.vq_max_pending)),
                vdev.vdev_queue.vq_max_pending);
            mdb_printf("%p agg limit        0x%llx\n",
                (uintptr_t)(addr + offsetof(vdev_t,
                vdev_queue.vq_agg_limit)),
                vdev.vdev_queue.vq_agg_limit);
            mdb_printf("%p time shift       0x%llx\n",
                (uintptr_t)(addr + offsetof(vdev_t,
                vdev_queue.vq_time_shift)),
                vdev.vdev_queue.vq_time_shift);
            mdb_printf("%p ramp rate        0x%llx\n",
                (uintptr_t)(addr + offsetof(vdev_t,
                vdev_queue.vq_ramp_rate)),
                vdev.vdev_queue.vq_ramp_rate);
            mdb_dec_indent(4);
        }

        if (stats) {
            vdev_stat_t *vs = &vdev.vdev_stat;
            int i;

            mdb_inc_indent(4);
            mdb_printf("\n");
            mdb_printf("%<u>       %12s %12s %12s %12s "
                "%12s%</u>\n", "READ", "WRITE", "FREE", "CLAIM",
                "IOCTL");
            mdb_printf("OPS     ");
            for (i = 1; i < ZIO_TYPES; i++)
                mdb_printf("%11#llx%s", vs->vs_ops[i],
                    i == ZIO_TYPES - 1 ? "" : "  ");
            mdb_printf("\n");
            mdb_printf("BYTES   ");
            for (i = 1; i < ZIO_TYPES; i++)
                mdb_printf("%11#llx%s", vs->vs_bytes[i],
                    i == ZIO_TYPES - 1 ? "" : "  ");


            mdb_printf("\n");
            mdb_printf("EREAD    %10#llx\n", vs->vs_read_errors);
            mdb_printf("EWRITE   %10#llx\n", vs->vs_write_errors);
            mdb_printf("ECKSUM   %10#llx\n",
                vs->vs_checksum_errors);
            mdb_dec_indent(4);
        }

        if (queue || stats)
            mdb_printf("\n");
    }

    children = vdev.vdev_children;

    if (children == 0 || !recursive)
        return (DCMD_OK);

    child = mdb_alloc(children * sizeof (void *), UM_SLEEP | UM_GC);
    if (mdb_vread(child, children * sizeof (void *),
        (uintptr_t)vdev.vdev_child) == -1) {
        mdb_warn("failed to read vdev children at %p", vdev.vdev_child);
        return (DCMD_ERR);
    }

    for (c = 0; c < children; c++) {
        if (do_print_vdev(child[c], flags, depth + 2, queue, stats,
            recursive))
            return (DCMD_ERR);
    }

    return (DCMD_OK);
}

static int
vdev_print(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
    int print_queue = FALSE;
    int recursive = FALSE;
    int stats = FALSE;

    if (mdb_getopts(argc, argv,
        'q', MDB_OPT_SETBITS, TRUE, &print_queue,
        'r', MDB_OPT_SETBITS, TRUE, &recursive,
        'e', MDB_OPT_SETBITS, TRUE, &stats,
        NULL) != argc)
        return (DCMD_USAGE);

    if (!(flags & DCMD_ADDRSPEC)) {
        mdb_warn("no vdev_t address given\n");
        return (DCMD_ERR);
    }

    return (do_print_vdev(addr, flags, 0, print_queue, stats, recursive));
}

typedef struct mdb_spa {
    uintptr_t spa_dsl_pool;
    uintptr_t spa_root_vdev;
} mdb_spa_t;

typedef struct mdb_dsl_dir {
    uintptr_t dd_phys;
    uint64_t dd_used_bytes;
    int64_t dd_space_towrite[TXG_SIZE];
} mdb_dsl_dir_t;

typedef struct mdb_dsl_dir_phys {
    uint64_t dd_used_bytes;
    uint64_t dd_compressed_bytes;
    uint64_t dd_uncompressed_bytes;
} mdb_dsl_dir_phys_t;

typedef struct mdb_vdev {
    uintptr_t vdev_parent;
    uintptr_t vdev_ms;
    uint64_t vdev_ms_count;
    vdev_stat_t vdev_stat;
} mdb_vdev_t;

typedef struct mdb_metaslab {
    space_map_t ms_allocmap[TXG_SIZE];
    space_map_t ms_freemap[TXG_SIZE];
    space_map_t ms_map;
    uint64_t ms_usable_space;
} mdb_metaslab_t;

/*
 * ::spa_space [-b]
 *
 * Given a spa_t, print out it's on-disk space usage and in-core
 * estimates of future usage.  If -b is given, print space in bytes.
 * Otherwise print in megabytes.
 */
/* ARGSUSED */
static int
spa_space(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
    mdb_spa_t spa;
    uintptr_t dp_root_dir;
    mdb_dsl_dir_t dd;
    mdb_dsl_dir_phys_t dsp;
    uint64_t children;
    uintptr_t childaddr;
    uintptr_t *child;
    uint64_t ms_allocmap[TXG_SIZE] = {0, 0, 0, 0};
    uint64_t ms_freemap[TXG_SIZE] = {0, 0, 0, 0};
    uint64_t ms_map = 0;
    uint64_t ms_usable_space = 0;
    int i, j;
    int havecompressed = TRUE;
    int shift = 20;
    char *suffix = "M";
    int bits = FALSE;

    if (mdb_getopts(argc, argv, 'b', MDB_OPT_SETBITS, TRUE, &bits, NULL) !=
        argc)
        return (DCMD_USAGE);
    if (!(flags & DCMD_ADDRSPEC))
        return (DCMD_USAGE);

    if (bits) {
        shift = 0;
        suffix = "";
    }

    if (GETMEMB(addr, struct spa, spa_dsl_pool, spa.spa_dsl_pool) ||
        GETMEMB(addr, struct spa, spa_root_vdev, spa.spa_root_vdev) ||
        GETMEMB(spa.spa_root_vdev, struct vdev, vdev_children, children) ||
        GETMEMB(spa.spa_root_vdev, struct vdev, vdev_child, childaddr) ||
        GETMEMB(spa.spa_dsl_pool, struct dsl_pool,
        dp_root_dir, dp_root_dir) ||
        GETMEMB(dp_root_dir, struct dsl_dir, dd_phys, dd.dd_phys) ||
        GETMEMB(dp_root_dir, struct dsl_dir,
        dd_used_bytes, dd.dd_used_bytes) ||
        GETMEMB(dp_root_dir, struct dsl_dir,
        dd_space_towrite, dd.dd_space_towrite) ||
        GETMEMB(dd.dd_phys, struct dsl_dir_phys,
        dd_used_bytes, dsp.dd_used_bytes)) {
        return (DCMD_ERR);
    }

    if (GETMEMB(dd.dd_phys, struct dsl_dir_phys,
        dd_compressed_bytes, dsp.dd_compressed_bytes) ||
        GETMEMB(dd.dd_phys, struct dsl_dir_phys,
        dd_uncompressed_bytes, dsp.dd_uncompressed_bytes)) {
        havecompressed = FALSE;
    }

    child = mdb_alloc(children * sizeof (void *), UM_SLEEP | UM_GC);
    if (mdb_vread(child, children * sizeof (void *), childaddr) == -1) {
        mdb_warn("failed to read root vdev children at %p", childaddr);
        return (DCMD_ERR);
    }

    mdb_printf("dd_space_towrite = %llu%s %llu%s %llu%s %llu%s\n",
        dd.dd_space_towrite[0] >> shift, suffix,
        dd.dd_space_towrite[1] >> shift, suffix,
        dd.dd_space_towrite[2] >> shift, suffix,
        dd.dd_space_towrite[3] >> shift, suffix);
    mdb_printf("dd_used_bytes = %llu%s\n",
        dd.dd_used_bytes >> shift, suffix);

    mdb_printf("dd_phys.dd_used_bytes = %llu%s\n",
        dsp.dd_used_bytes >> shift, suffix);
    if (havecompressed) {
        mdb_printf("dd_phys.dd_compressed_bytes = %llu%s\n",
            dsp.dd_compressed_bytes >> shift, suffix);
        mdb_printf("dd_phys.dd_uncompressed_bytes = %llu%s\n",
            dsp.dd_uncompressed_bytes >> shift, suffix);
    }

    for (i = 0; i < children; i++) {
        mdb_vdev_t vd;
        uintptr_t *vdev_ms;

        if (GETMEMB(child[i], struct vdev,
            vdev_parent, vd.vdev_parent) ||
            GETMEMB(child[i], struct vdev,
            vdev_stat, vd.vdev_stat) ||
            GETMEMB(child[i], struct vdev, vdev_ms, vd.vdev_ms) ||
            GETMEMB(child[i], struct vdev,
            vdev_ms_count, vd.vdev_ms_count)) {
            return (DCMD_ERR);
        }

        /*
         * If this is the root vdev, its stats are the pool-wide stats.
         */
        if (vd.vdev_parent == NULL) {
            mdb_printf("pool_alloc = %llu%s\n",
                vd.vdev_stat.vs_alloc >> shift, suffix);
            mdb_printf("pool_space = %llu%s\n",
                vd.vdev_stat.vs_space >> shift, suffix);
        }

        /*
         * If this is not a top-level vdev, it doesn't have space.
         */
        if (vd.vdev_parent != spa.spa_root_vdev)
            continue;

        vdev_ms = mdb_alloc(vd.vdev_ms_count * sizeof (void*),
            UM_SLEEP | UM_GC);
        if (mdb_vread(vdev_ms, vd.vdev_ms_count * sizeof (void*),
            (uintptr_t)vd.vdev_ms) == -1) {
            mdb_warn("failed to read vdev_ms at %p", vd.vdev_ms);
            return (DCMD_ERR);
        }

        for (j = 0; j < vd.vdev_ms_count; j++) {
            mdb_metaslab_t ms;

            if (GETMEMB(vdev_ms[j], struct metaslab,
                ms_allocmap, ms.ms_allocmap) ||
                GETMEMB(vdev_ms[j], struct metaslab,
                ms_freemap, ms.ms_freemap) ||
                GETMEMB(vdev_ms[j], struct metaslab,
                ms_map, ms.ms_map) ||
                GETMEMB(vdev_ms[j], struct metaslab,
                ms_usable_space, ms.ms_usable_space)) {
                return (DCMD_ERR);
            }

            ms_allocmap[0] += ms.ms_allocmap[0].sm_space;
            ms_allocmap[1] += ms.ms_allocmap[1].sm_space;
            ms_allocmap[2] += ms.ms_allocmap[2].sm_space;
            ms_allocmap[3] += ms.ms_allocmap[3].sm_space;
            ms_freemap[0] += ms.ms_freemap[0].sm_space;
            ms_freemap[1] += ms.ms_freemap[1].sm_space;
            ms_freemap[2] += ms.ms_freemap[2].sm_space;
            ms_freemap[3] += ms.ms_freemap[3].sm_space;
            ms_map += ms.ms_map.sm_space;
            ms_usable_space += ms.ms_usable_space;
        }
    }

    mdb_printf("ms_allocmap = %llu%s %llu%s %llu%s %llu%s\n",
        ms_allocmap[0] >> shift, suffix,
        ms_allocmap[1] >> shift, suffix,
        ms_allocmap[2] >> shift, suffix,
        ms_allocmap[3] >> shift, suffix);
    mdb_printf("ms_freemap = %llu%s %llu%s %llu%s %llu%s\n",
        ms_freemap[0] >> shift, suffix,
        ms_freemap[1] >> shift, suffix,
        ms_freemap[2] >> shift, suffix,
        ms_freemap[3] >> shift, suffix);
    mdb_printf("ms_map = %llu%s\n", ms_map >> shift, suffix);
    mdb_printf("ms_usable_space = %llu%s\n",
        ms_usable_space >> shift, suffix);

    return (DCMD_OK);
}

/*
 * ::spa_verify
 *
 * Given a spa_t, verify that that the pool is self-consistent.
 * Currently, it only checks to make sure that the vdev tree exists.
 */
/* ARGSUSED */
static int
spa_verify(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
    spa_t spa;

    if (argc != 0 || !(flags & DCMD_ADDRSPEC))
        return (DCMD_USAGE);

    if (mdb_vread(&spa, sizeof (spa), addr) == -1) {
        mdb_warn("failed to read spa_t at %p", addr);
        return (DCMD_ERR);
    }

    if (spa.spa_root_vdev == NULL) {
        mdb_printf("no vdev tree present\n");
        return (DCMD_OK);
    }

    return (DCMD_OK);
}

/*
 * ::spa_vdevs
 *
 *  -e  Include error stats
 *
 * Print out a summarized list of vdevs for the given spa_t.
 * This is accomplished by invoking "::vdev -re" on the root vdev.
 */
/* ARGSUSED */
static int
spa_vdevs(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
    spa_t spa;
    mdb_arg_t v;
    int errors = FALSE;

    if (mdb_getopts(argc, argv,
        'e', MDB_OPT_SETBITS, TRUE, &errors,
        NULL) != argc)
        return (DCMD_USAGE);

    if (!(flags & DCMD_ADDRSPEC))
        return (DCMD_USAGE);

    if (mdb_vread(&spa, sizeof (spa), addr) == -1) {
        mdb_warn("failed to read spa_t at %p", addr);
        return (DCMD_ERR);
    }

    /*
     * Unitialized spa_t structures can have a NULL root vdev.
     */
    if (spa.spa_root_vdev == NULL) {
        mdb_printf("no associated vdevs\n");
        return (DCMD_OK);
    }

    v.a_type = MDB_TYPE_STRING;
    v.a_un.a_str = errors ? "-re" : "-r";

    return (mdb_call_dcmd("vdev", (uintptr_t)spa.spa_root_vdev,
        flags, 1, &v));
}

typedef struct txg_list_walk_data {
    uintptr_t lw_head[TXG_SIZE];
    int lw_txgoff;
    int lw_maxoff;
    size_t  lw_offset;
    void    *lw_obj;
} txg_list_walk_data_t;

static int
txg_list_walk_init_common(mdb_walk_state_t *wsp, int txg, int maxoff)
{
    txg_list_walk_data_t *lwd;
    txg_list_t list;
    int i;

    lwd = mdb_alloc(sizeof (txg_list_walk_data_t), UM_SLEEP | UM_GC);
    if (mdb_vread(&list, sizeof (txg_list_t), wsp->walk_addr) == -1) {
        mdb_warn("failed to read txg_list_t at %#lx", wsp->walk_addr);
        return (WALK_ERR);
    }

    for (i = 0; i < TXG_SIZE; i++)
        lwd->lw_head[i] = (uintptr_t)list.tl_head[i];
    lwd->lw_offset = list.tl_offset;
    lwd->lw_obj = mdb_alloc(lwd->lw_offset + sizeof (txg_node_t),
        UM_SLEEP | UM_GC);
    lwd->lw_txgoff = txg;
    lwd->lw_maxoff = maxoff;

    wsp->walk_addr = lwd->lw_head[lwd->lw_txgoff];
    wsp->walk_data = lwd;

    return (WALK_NEXT);
}

static int
txg_list_walk_init(mdb_walk_state_t *wsp)
{
    return (txg_list_walk_init_common(wsp, 0, TXG_SIZE-1));
}

static int
txg_list0_walk_init(mdb_walk_state_t *wsp)
{
    return (txg_list_walk_init_common(wsp, 0, 0));
}

static int
txg_list1_walk_init(mdb_walk_state_t *wsp)
{
    return (txg_list_walk_init_common(wsp, 1, 1));
}

static int
txg_list2_walk_init(mdb_walk_state_t *wsp)
{
    return (txg_list_walk_init_common(wsp, 2, 2));
}

static int
txg_list3_walk_init(mdb_walk_state_t *wsp)
{
    return (txg_list_walk_init_common(wsp, 3, 3));
}

static int
txg_list_walk_step(mdb_walk_state_t *wsp)
{
    txg_list_walk_data_t *lwd = wsp->walk_data;
    uintptr_t addr;
    txg_node_t *node;
    int status;

    while (wsp->walk_addr == NULL && lwd->lw_txgoff < lwd->lw_maxoff) {
        lwd->lw_txgoff++;
        wsp->walk_addr = lwd->lw_head[lwd->lw_txgoff];
    }

    if (wsp->walk_addr == NULL)
        return (WALK_DONE);

    addr = wsp->walk_addr - lwd->lw_offset;

    if (mdb_vread(lwd->lw_obj,
        lwd->lw_offset + sizeof (txg_node_t), addr) == -1) {
        mdb_warn("failed to read list element at %#lx", addr);
        return (WALK_ERR);
    }

    status = wsp->walk_callback(addr, lwd->lw_obj, wsp->walk_cbdata);
    node = (txg_node_t *)((uintptr_t)lwd->lw_obj + lwd->lw_offset);
    wsp->walk_addr = (uintptr_t)node->tn_next[lwd->lw_txgoff];

    return (status);
}

/* ARGSUSED */
static void
txg_list_walk_fini(mdb_walk_state_t *wsp)
{
}

/*
 * ::walk spa
 *
 * Walk all named spa_t structures in the namespace.  This is nothing more than
 * a layered avl walk.
 */
static int
spa_walk_init(mdb_walk_state_t *wsp)
{
    GElf_Sym sym;

    if (wsp->walk_addr != NULL) {
        mdb_warn("spa walk only supports global walks\n");
        return (WALK_ERR);
    }

    if (mdb_lookup_by_obj(ZFS_OBJ_NAME, "spa_namespace_avl", &sym) == -1) {
        mdb_warn("failed to find symbol 'spa_namespace_avl'");
        return (WALK_ERR);
    }

    wsp->walk_addr = (uintptr_t)sym.st_value;

    if (mdb_layered_walk("avl", wsp) == -1) {
        mdb_warn("failed to walk 'avl'\n");
        return (WALK_ERR);
    }

    return (WALK_NEXT);
}

static int
spa_walk_step(mdb_walk_state_t *wsp)
{
    spa_t   spa;

    if (mdb_vread(&spa, sizeof (spa), wsp->walk_addr) == -1) {
        mdb_warn("failed to read spa_t at %p", wsp->walk_addr);
        return (WALK_ERR);
    }

    return (wsp->walk_callback(wsp->walk_addr, &spa, wsp->walk_cbdata));
}

/*
 * MDB module linkage information:
 *
 * We declare a list of structures describing our dcmds, and a function
 * named _mdb_init to return a pointer to our module information.
 */

static const mdb_dcmd_t dcmds[] = {
    { "blkptr", ":", "print blkptr_t", blkptr },
    { "dbuf", ":", "print dmu_buf_impl_t", dbuf },
    { "dbuf_stats", ":", "dbuf stats", dbuf_stats },
    { "dbufs",
    "\t[-O objset_t*] [-n objset_name | \"mos\"] [-o object | \"mdn\"] \n"
    "\t[-l level] [-b blkid | \"bonus\"]",
    "find dmu_buf_impl_t's that meet criterion", dbufs },
    { "abuf_find", "dva_word[0] dva_word[1]",
    "find arc_buf_hdr_t of a specified DVA",
    abuf_find },
    { "spa", "?[-cv]", "spa_t summary", spa_print },
    { "spa_config", ":", "print spa_t configuration", spa_print_config },
    { "spa_verify", ":", "verify spa_t consistency", spa_verify },
    { "spa_space", ":[-b]", "print spa_t on-disk space usage", spa_space },
    { "spa_vdevs", ":", "given a spa_t, print vdev summary", spa_vdevs },
    { "vdev", ":[-qre]", "vdev_t summary", vdev_print },
    { "zio_pipeline", ":", "decode a zio pipeline", zio_pipeline },
    { NULL }
};

static const mdb_walker_t walkers[] = {
    /*
     * In userland, there is no generic provider of list_t walkers, so we
     * need to add it.
     */
#ifndef _KERNEL
    { LIST_WALK_NAME, LIST_WALK_DESC,
        list_walk_init, list_walk_step, list_walk_fini },
#endif
    { "dbufs", "walk cached ZFS dbufs",
        dbuf_walk_init, dbuf_walk_step, dbuf_walk_fini },
    { "zms_freelist", "walk ZFS metaslab freelist",
        freelist_walk_init, freelist_walk_step, freelist_walk_fini },
    { "txg_list", "given any txg_list_t *, walk all entries in all txgs",
        txg_list_walk_init, txg_list_walk_step, txg_list_walk_fini },
    { "txg_list0", "given any txg_list_t *, walk all entries in txg 0",
        txg_list0_walk_init, txg_list_walk_step, txg_list_walk_fini },
    { "txg_list1", "given any txg_list_t *, walk all entries in txg 1",
        txg_list1_walk_init, txg_list_walk_step, txg_list_walk_fini },
    { "txg_list2", "given any txg_list_t *, walk all entries in txg 2",
        txg_list2_walk_init, txg_list_walk_step, txg_list_walk_fini },
    { "txg_list3", "given any txg_list_t *, walk all entries in txg 3",
        txg_list3_walk_init, txg_list_walk_step, txg_list_walk_fini },
    { "spa", "walk all spa_t entries in the namespace",
        spa_walk_init, spa_walk_step, NULL },
    { NULL }
};

static const mdb_modinfo_t modinfo = {
    MDB_API_VERSION, dcmds, walkers
};

const mdb_modinfo_t *
_mdb_init(void)
{
    return (&modinfo);
}