[zfs.git] / cmd / ztest / ztest.c

/*
 * 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 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * The objective of this program is to provide a DMU/ZAP/SPA stress test
 * that runs entirely in userland, is easy to use, and easy to extend.
 *
 * The overall design of the ztest program is as follows:
 *
 * (1) For each major functional area (e.g. adding vdevs to a pool,
 *     creating and destroying datasets, reading and writing objects, etc)
 *     we have a simple routine to test that functionality.  These
 *     individual routines do not have to do anything "stressful".
 *
 * (2) We turn these simple functionality tests into a stress test by
 *     running them all in parallel, with as many threads as desired,
 *     and spread across as many datasets, objects, and vdevs as desired.
 *
 * (3) While all this is happening, we inject faults into the pool to
 *     verify that self-healing data really works.
 *
 * (4) Every time we open a dataset, we change its checksum and compression
 *     functions.  Thus even individual objects vary from block to block
 *     in which checksum they use and whether they're compressed.
 *
 * (5) To verify that we never lose on-disk consistency after a crash,
 *     we run the entire test in a child of the main process.
 *     At random times, the child self-immolates with a SIGKILL.
 *     This is the software equivalent of pulling the power cord.
 *     The parent then runs the test again, using the existing
 *     storage pool, as many times as desired.
 *
 * (6) To verify that we don't have future leaks or temporal incursions,
 *     many of the functional tests record the transaction group number
 *     as part of their data.  When reading old data, they verify that
 *     the transaction group number is less than the current, open txg.
 *     If you add a new test, please do this if applicable.
 *
 * When run with no arguments, ztest runs for about five minutes and
 * produces no output if successful.  To get a little bit of information,
 * specify -V.  To get more information, specify -VV, and so on.
 *
 * To turn this into an overnight stress test, use -T to specify run time.
 *
 * You can ask more more vdevs [-v], datasets [-d], or threads [-t]
 * to increase the pool capacity, fanout, and overall stress level.
 *
 * The -N(okill) option will suppress kills, so each child runs to completion.
 * This can be useful when you're trying to distinguish temporal incursions
 * from plain old race conditions.
 */

#include <sys/zfs_context.h>
#include <sys/spa.h>
#include <sys/dmu.h>
#include <sys/txg.h>
#include <sys/dbuf.h>
#include <sys/zap.h>
#include <sys/dmu_objset.h>
#include <sys/poll.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include <sys/resource.h>
#include <sys/zio.h>
#include <sys/zio_checksum.h>
#include <sys/zio_compress.h>
#include <sys/zil.h>
#include <sys/vdev_impl.h>
#include <sys/vdev_file.h>
#include <sys/spa_impl.h>
#include <sys/dsl_prop.h>
#include <sys/dsl_dataset.h>
#include <sys/refcount.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <umem.h>
#include <dlfcn.h>
#include <ctype.h>
#include <math.h>
#include <sys/fs/zfs.h>

static char cmdname[] = "ztest";
static char *zopt_pool = cmdname;

static uint64_t zopt_vdevs = 5;
static uint64_t zopt_vdevtime;
static int zopt_ashift = SPA_MINBLOCKSHIFT;
static int zopt_mirrors = 2;
static int zopt_raidz = 4;
static int zopt_raidz_parity = 1;
static size_t zopt_vdev_size = SPA_MINDEVSIZE;
static int zopt_datasets = 7;
static int zopt_threads = 23;
static uint64_t zopt_passtime = 60;     /* 60 seconds */
static uint64_t zopt_killrate = 70;     /* 70% kill rate */
static int zopt_verbose = 0;
static int zopt_init = 1;
static char *zopt_dir = "/tmp";
static uint64_t zopt_time = 300;        /* 5 minutes */
static int zopt_maxfaults;

typedef struct ztest_block_tag {
        uint64_t        bt_objset;
        uint64_t        bt_object;
        uint64_t        bt_offset;
        uint64_t        bt_txg;
        uint64_t        bt_thread;
        uint64_t        bt_seq;
} ztest_block_tag_t;

typedef struct ztest_args {
        char            za_pool[MAXNAMELEN];
        spa_t           *za_spa;
        objset_t        *za_os;
        zilog_t         *za_zilog;
        thread_t        za_thread;
        uint64_t        za_instance;
        uint64_t        za_random;
        uint64_t        za_diroff;
        uint64_t        za_diroff_shared;
        uint64_t        za_zil_seq;
        hrtime_t        za_start;
        hrtime_t        za_stop;
        hrtime_t        za_kill;
        /*
         * Thread-local variables can go here to aid debugging.
         */
        ztest_block_tag_t za_rbt;
        ztest_block_tag_t za_wbt;
        dmu_object_info_t za_doi;
        dmu_buf_t       *za_dbuf;
} ztest_args_t;

typedef void ztest_func_t(ztest_args_t *);

/*
 * Note: these aren't static because we want dladdr() to work.
 */
ztest_func_t ztest_dmu_read_write;
ztest_func_t ztest_dmu_read_write_zcopy;
ztest_func_t ztest_dmu_write_parallel;
ztest_func_t ztest_dmu_object_alloc_free;
ztest_func_t ztest_zap;
ztest_func_t ztest_zap_parallel;
ztest_func_t ztest_traverse;
ztest_func_t ztest_dsl_prop_get_set;
ztest_func_t ztest_dmu_objset_create_destroy;
ztest_func_t ztest_dmu_snapshot_create_destroy;
ztest_func_t ztest_dsl_dataset_promote_busy;
ztest_func_t ztest_spa_create_destroy;
ztest_func_t ztest_fault_inject;
ztest_func_t ztest_spa_rename;
ztest_func_t ztest_vdev_attach_detach;
ztest_func_t ztest_vdev_LUN_growth;
ztest_func_t ztest_vdev_add_remove;
ztest_func_t ztest_vdev_aux_add_remove;
ztest_func_t ztest_scrub;

typedef struct ztest_info {
        ztest_func_t    *zi_func;       /* test function */
        uint64_t        zi_iters;       /* iterations per execution */
        uint64_t        *zi_interval;   /* execute every <interval> seconds */
        uint64_t        zi_calls;       /* per-pass count */
        uint64_t        zi_call_time;   /* per-pass time */
        uint64_t        zi_call_total;  /* cumulative total */
        uint64_t        zi_call_target; /* target cumulative total */
} ztest_info_t;

uint64_t zopt_always = 0;               /* all the time */
uint64_t zopt_often = 1;                /* every second */
uint64_t zopt_sometimes = 10;           /* every 10 seconds */
uint64_t zopt_rarely = 60;              /* every 60 seconds */

ztest_info_t ztest_info[] = {
        { ztest_dmu_read_write,                 1,      &zopt_always    },
        { ztest_dmu_read_write_zcopy,           1,      &zopt_always    },
        { ztest_dmu_write_parallel,             30,     &zopt_always    },
        { ztest_dmu_object_alloc_free,          1,      &zopt_always    },
        { ztest_zap,                            30,     &zopt_always    },
        { ztest_zap_parallel,                   100,    &zopt_always    },
        { ztest_dsl_prop_get_set,               1,      &zopt_sometimes },
        { ztest_dmu_objset_create_destroy,      1,      &zopt_sometimes },
        { ztest_dmu_snapshot_create_destroy,    1,      &zopt_sometimes },
        { ztest_spa_create_destroy,             1,      &zopt_sometimes },
        { ztest_fault_inject,                   1,      &zopt_sometimes },
        { ztest_spa_rename,                     1,      &zopt_rarely    },
        { ztest_vdev_attach_detach,             1,      &zopt_rarely    },
        { ztest_vdev_LUN_growth,                1,      &zopt_rarely    },
        { ztest_dsl_dataset_promote_busy,       1,      &zopt_rarely    },
        { ztest_vdev_add_remove,                1,      &zopt_vdevtime  },
        { ztest_vdev_aux_add_remove,            1,      &zopt_vdevtime  },
        { ztest_scrub,                          1,      &zopt_vdevtime  },
};

#define ZTEST_FUNCS     (sizeof (ztest_info) / sizeof (ztest_info_t))

#define ZTEST_SYNC_LOCKS        16

/*
 * Stuff we need to share writably between parent and child.
 */
typedef struct ztest_shared {
        mutex_t         zs_vdev_lock;
        rwlock_t        zs_name_lock;
        uint64_t        zs_vdev_primaries;
        uint64_t        zs_vdev_aux;
        uint64_t        zs_enospc_count;
        hrtime_t        zs_start_time;
        hrtime_t        zs_stop_time;
        uint64_t        zs_alloc;
        uint64_t        zs_space;
        ztest_info_t    zs_info[ZTEST_FUNCS];
        mutex_t         zs_sync_lock[ZTEST_SYNC_LOCKS];
        uint64_t        zs_seq[ZTEST_SYNC_LOCKS];
} ztest_shared_t;

static char ztest_dev_template[] = "%s/%s.%llua";
static char ztest_aux_template[] = "%s/%s.%s.%llu";
static ztest_shared_t *ztest_shared;

static int ztest_random_fd;
static int ztest_dump_core = 1;

static uint64_t metaslab_sz;
static boolean_t ztest_exiting;

extern uint64_t metaslab_gang_bang;
extern uint64_t metaslab_df_alloc_threshold;

#define ZTEST_DIROBJ            1
#define ZTEST_MICROZAP_OBJ      2
#define ZTEST_FATZAP_OBJ        3

#define ZTEST_DIROBJ_BLOCKSIZE  (1 << 10)
#define ZTEST_DIRSIZE           256

static void usage(boolean_t) __NORETURN;

/*
 * These libumem hooks provide a reasonable set of defaults for the allocator's
 * debugging facilities.
 */
const char *
_umem_debug_init()
{
        return ("default,verbose"); /* $UMEM_DEBUG setting */
}

const char *
_umem_logging_init(void)
{
        return ("fail,contents"); /* $UMEM_LOGGING setting */
}

#define FATAL_MSG_SZ    1024

char *fatal_msg;

static void
fatal(int do_perror, char *message, ...)
{
        va_list args;
        int save_errno = errno;
        char buf[FATAL_MSG_SZ];

        (void) fflush(stdout);

        va_start(args, message);
        (void) sprintf(buf, "ztest: ");
        /* LINTED */
        (void) vsprintf(buf + strlen(buf), message, args);
        va_end(args);
        if (do_perror) {
                (void) snprintf(buf + strlen(buf), FATAL_MSG_SZ - strlen(buf),
                    ": %s", strerror(save_errno));
        }
        (void) fprintf(stderr, "%s\n", buf);
        fatal_msg = buf;                        /* to ease debugging */
        if (ztest_dump_core)
                abort();
        exit(3);
}

static int
str2shift(const char *buf)
{
        const char *ends = "BKMGTPEZ";
        int i;

        if (buf[0] == '\0')
                return (0);
        for (i = 0; i < strlen(ends); i++) {
                if (toupper(buf[0]) == ends[i])
                        break;
        }
        if (i == strlen(ends)) {
                (void) fprintf(stderr, "ztest: invalid bytes suffix: %s\n",
                    buf);
                usage(B_FALSE);
        }
        if (buf[1] == '\0' || (toupper(buf[1]) == 'B' && buf[2] == '\0')) {
                return (10*i);
        }
        (void) fprintf(stderr, "ztest: invalid bytes suffix: %s\n", buf);
        usage(B_FALSE);
        /* NOTREACHED */
}

static uint64_t
nicenumtoull(const char *buf)
{
        char *end;
        uint64_t val;

        val = strtoull(buf, &end, 0);
        if (end == buf) {
                (void) fprintf(stderr, "ztest: bad numeric value: %s\n", buf);
                usage(B_FALSE);
        } else if (end[0] == '.') {
                double fval = strtod(buf, &end);
                fval *= pow(2, str2shift(end));
                if (fval > UINT64_MAX) {
                        (void) fprintf(stderr, "ztest: value too large: %s\n",
                            buf);
                        usage(B_FALSE);
                }
                val = (uint64_t)fval;
        } else {
                int shift = str2shift(end);
                if (shift >= 64 || (val << shift) >> shift != val) {
                        (void) fprintf(stderr, "ztest: value too large: %s\n",
                            buf);
                        usage(B_FALSE);
                }
                val <<= shift;
        }
        return (val);
}

static void
usage(boolean_t requested)
{
        char nice_vdev_size[10];
        char nice_gang_bang[10];
        FILE *fp = requested ? stdout : stderr;

        nicenum(zopt_vdev_size, nice_vdev_size);
        nicenum(metaslab_gang_bang, nice_gang_bang);

        (void) fprintf(fp, "Usage: %s\n"
            "\t[-v vdevs (default: %llu)]\n"
            "\t[-s size_of_each_vdev (default: %s)]\n"
            "\t[-a alignment_shift (default: %d) (use 0 for random)]\n"
            "\t[-m mirror_copies (default: %d)]\n"
            "\t[-r raidz_disks (default: %d)]\n"
            "\t[-R raidz_parity (default: %d)]\n"
            "\t[-d datasets (default: %d)]\n"
            "\t[-t threads (default: %d)]\n"
            "\t[-g gang_block_threshold (default: %s)]\n"
            "\t[-i initialize pool i times (default: %d)]\n"
            "\t[-k kill percentage (default: %llu%%)]\n"
            "\t[-p pool_name (default: %s)]\n"
            "\t[-f file directory for vdev files (default: %s)]\n"
            "\t[-V(erbose)] (use multiple times for ever more blather)\n"
            "\t[-E(xisting)] (use existing pool instead of creating new one)\n"
            "\t[-T time] total run time (default: %llu sec)\n"
            "\t[-P passtime] time per pass (default: %llu sec)\n"
            "\t[-h] (print help)\n"
            "",
            cmdname,
            (u_longlong_t)zopt_vdevs,                   /* -v */
            nice_vdev_size,                             /* -s */
            zopt_ashift,                                /* -a */
            zopt_mirrors,                               /* -m */
            zopt_raidz,                                 /* -r */
            zopt_raidz_parity,                          /* -R */
            zopt_datasets,                              /* -d */
            zopt_threads,                               /* -t */
            nice_gang_bang,                             /* -g */
            zopt_init,                                  /* -i */
            (u_longlong_t)zopt_killrate,                /* -k */
            zopt_pool,                                  /* -p */
            zopt_dir,                                   /* -f */
            (u_longlong_t)zopt_time,                    /* -T */
            (u_longlong_t)zopt_passtime);               /* -P */
        exit(requested ? 0 : 1);
}

static uint64_t
ztest_random(uint64_t range)
{
        uint64_t r;

        if (range == 0)
                return (0);

        if (read(ztest_random_fd, &r, sizeof (r)) != sizeof (r))
                fatal(1, "short read from /dev/urandom");

        return (r % range);
}

/* ARGSUSED */
static void
ztest_record_enospc(char *s)
{
        ztest_shared->zs_enospc_count++;
}

static void
process_options(int argc, char **argv)
{
        int opt;
        uint64_t value;

        /* By default, test gang blocks for blocks 32K and greater */
        metaslab_gang_bang = 32 << 10;

        while ((opt = getopt(argc, argv,
            "v:s:a:m:r:R:d:t:g:i:k:p:f:VET:P:h")) != EOF) {
                value = 0;
                switch (opt) {
                case 'v':
                case 's':
                case 'a':
                case 'm':
                case 'r':
                case 'R':
                case 'd':
                case 't':
                case 'g':
                case 'i':
                case 'k':
                case 'T':
                case 'P':
                        value = nicenumtoull(optarg);
                }
                switch (opt) {
                case 'v':
                        zopt_vdevs = value;
                        break;
                case 's':
                        zopt_vdev_size = MAX(SPA_MINDEVSIZE, value);
                        break;
                case 'a':
                        zopt_ashift = value;
                        break;
                case 'm':
                        zopt_mirrors = value;
                        break;
                case 'r':
                        zopt_raidz = MAX(1, value);
                        break;
                case 'R':
                        zopt_raidz_parity = MIN(MAX(value, 1), 3);
                        break;
                case 'd':
                        zopt_datasets = MAX(1, value);
                        break;
                case 't':
                        zopt_threads = MAX(1, value);
                        break;
                case 'g':
                        metaslab_gang_bang = MAX(SPA_MINBLOCKSIZE << 1, value);
                        break;
                case 'i':
                        zopt_init = value;
                        break;
                case 'k':
                        zopt_killrate = value;
                        break;
                case 'p':
                        zopt_pool = strdup(optarg);
                        break;
                case 'f':
                        zopt_dir = strdup(optarg);
                        break;
                case 'V':
                        zopt_verbose++;
                        break;
                case 'E':
                        zopt_init = 0;
                        break;
                case 'T':
                        zopt_time = value;
                        break;
                case 'P':
                        zopt_passtime = MAX(1, value);
                        break;
                case 'h':
                        usage(B_TRUE);
                        break;
                case '?':
                default:
                        usage(B_FALSE);
                        break;
                }
        }

        zopt_raidz_parity = MIN(zopt_raidz_parity, zopt_raidz - 1);

        zopt_vdevtime = (zopt_vdevs > 0 ? zopt_time / zopt_vdevs : UINT64_MAX);
        zopt_maxfaults = MAX(zopt_mirrors, 1) * (zopt_raidz_parity + 1) - 1;
}

static uint64_t
ztest_get_ashift(void)
{
        if (zopt_ashift == 0)
                return (SPA_MINBLOCKSHIFT + ztest_random(3));
        return (zopt_ashift);
}

static nvlist_t *
make_vdev_file(char *path, char *aux, size_t size, uint64_t ashift)
{
        char pathbuf[MAXPATHLEN];
        uint64_t vdev;
        nvlist_t *file;

        if (ashift == 0)
                ashift = ztest_get_ashift();

        if (path == NULL) {
                path = pathbuf;

                if (aux != NULL) {
                        vdev = ztest_shared->zs_vdev_aux;
                        (void) sprintf(path, ztest_aux_template,
                            zopt_dir, zopt_pool, aux, vdev);
                } else {
                        vdev = ztest_shared->zs_vdev_primaries++;
                        (void) sprintf(path, ztest_dev_template,
                            zopt_dir, zopt_pool, vdev);
                }
        }

        if (size != 0) {
                int fd = open(path, O_RDWR | O_CREAT | O_TRUNC, 0666);
                if (fd == -1)
                        fatal(1, "can't open %s", path);
                if (ftruncate(fd, size) != 0)
                        fatal(1, "can't ftruncate %s", path);
                (void) close(fd);
        }

        VERIFY(nvlist_alloc(&file, NV_UNIQUE_NAME, 0) == 0);
        VERIFY(nvlist_add_string(file, ZPOOL_CONFIG_TYPE, VDEV_TYPE_FILE) == 0);
        VERIFY(nvlist_add_string(file, ZPOOL_CONFIG_PATH, path) == 0);
        VERIFY(nvlist_add_uint64(file, ZPOOL_CONFIG_ASHIFT, ashift) == 0);

        return (file);
}

static nvlist_t *
make_vdev_raidz(char *path, char *aux, size_t size, uint64_t ashift, int r)
{
        nvlist_t *raidz, **child;
        int c;

        if (r < 2)
                return (make_vdev_file(path, aux, size, ashift));
        child = umem_alloc(r * sizeof (nvlist_t *), UMEM_NOFAIL);

        for (c = 0; c < r; c++)
                child[c] = make_vdev_file(path, aux, size, ashift);

        VERIFY(nvlist_alloc(&raidz, NV_UNIQUE_NAME, 0) == 0);
        VERIFY(nvlist_add_string(raidz, ZPOOL_CONFIG_TYPE,
            VDEV_TYPE_RAIDZ) == 0);
        VERIFY(nvlist_add_uint64(raidz, ZPOOL_CONFIG_NPARITY,
            zopt_raidz_parity) == 0);
        VERIFY(nvlist_add_nvlist_array(raidz, ZPOOL_CONFIG_CHILDREN,
            child, r) == 0);

        for (c = 0; c < r; c++)
                nvlist_free(child[c]);

        umem_free(child, r * sizeof (nvlist_t *));

        return (raidz);
}

static nvlist_t *
make_vdev_mirror(char *path, char *aux, size_t size, uint64_t ashift,
        int r, int m)
{
        nvlist_t *mirror, **child;
        int c;

        if (m < 1)
                return (make_vdev_raidz(path, aux, size, ashift, r));

        child = umem_alloc(m * sizeof (nvlist_t *), UMEM_NOFAIL);

        for (c = 0; c < m; c++)
                child[c] = make_vdev_raidz(path, aux, size, ashift, r);

        VERIFY(nvlist_alloc(&mirror, NV_UNIQUE_NAME, 0) == 0);
        VERIFY(nvlist_add_string(mirror, ZPOOL_CONFIG_TYPE,
            VDEV_TYPE_MIRROR) == 0);
        VERIFY(nvlist_add_nvlist_array(mirror, ZPOOL_CONFIG_CHILDREN,
            child, m) == 0);

        for (c = 0; c < m; c++)
                nvlist_free(child[c]);

        umem_free(child, m * sizeof (nvlist_t *));

        return (mirror);
}

static nvlist_t *
make_vdev_root(char *path, char *aux, size_t size, uint64_t ashift,
        int log, int r, int m, int t)
{
        nvlist_t *root, **child;
        int c;

        ASSERT(t > 0);

        child = umem_alloc(t * sizeof (nvlist_t *), UMEM_NOFAIL);

        for (c = 0; c < t; c++) {
                child[c] = make_vdev_mirror(path, aux, size, ashift, r, m);
                VERIFY(nvlist_add_uint64(child[c], ZPOOL_CONFIG_IS_LOG,
                    log) == 0);
        }

        VERIFY(nvlist_alloc(&root, NV_UNIQUE_NAME, 0) == 0);
        VERIFY(nvlist_add_string(root, ZPOOL_CONFIG_TYPE, VDEV_TYPE_ROOT) == 0);
        VERIFY(nvlist_add_nvlist_array(root, aux ? aux : ZPOOL_CONFIG_CHILDREN,
            child, t) == 0);

        for (c = 0; c < t; c++)
                nvlist_free(child[c]);

        umem_free(child, t * sizeof (nvlist_t *));

        return (root);
}

static void
ztest_set_random_blocksize(objset_t *os, uint64_t object, dmu_tx_t *tx)
{
        int bs = SPA_MINBLOCKSHIFT +
            ztest_random(SPA_MAXBLOCKSHIFT - SPA_MINBLOCKSHIFT + 1);
        int ibs = DN_MIN_INDBLKSHIFT +
            ztest_random(DN_MAX_INDBLKSHIFT - DN_MIN_INDBLKSHIFT + 1);
        int error;

        error = dmu_object_set_blocksize(os, object, 1ULL << bs, ibs, tx);
        if (error) {
                char osname[300];
                dmu_objset_name(os, osname);
                fatal(0, "dmu_object_set_blocksize('%s', %llu, %d, %d) = %d",
                    osname, object, 1 << bs, ibs, error);
        }
}

static uint8_t
ztest_random_checksum(void)
{
        uint8_t checksum;

        do {
                checksum = ztest_random(ZIO_CHECKSUM_FUNCTIONS);
        } while (zio_checksum_table[checksum].ci_zbt);

        if (checksum == ZIO_CHECKSUM_OFF)
                checksum = ZIO_CHECKSUM_ON;

        return (checksum);
}

static uint8_t
ztest_random_compress(void)
{
        return ((uint8_t)ztest_random(ZIO_COMPRESS_FUNCTIONS));
}

static int
ztest_replay_create(objset_t *os, lr_create_t *lr, boolean_t byteswap)
{
        dmu_tx_t *tx;
        int error;

        if (byteswap)
                byteswap_uint64_array(lr, sizeof (*lr));

        tx = dmu_tx_create(os);
        dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                return (error);
        }

        error = dmu_object_claim(os, lr->lr_doid, lr->lr_mode, 0,
            DMU_OT_NONE, 0, tx);
        ASSERT3U(error, ==, 0);
        dmu_tx_commit(tx);

        if (zopt_verbose >= 5) {
                char osname[MAXNAMELEN];
                dmu_objset_name(os, osname);
                (void) printf("replay create of %s object %llu"
                    " in txg %llu = %d\n",
                    osname, (u_longlong_t)lr->lr_doid,
                    (u_longlong_t)dmu_tx_get_txg(tx), error);
        }

        return (error);
}

static int
ztest_replay_remove(objset_t *os, lr_remove_t *lr, boolean_t byteswap)
{
        dmu_tx_t *tx;
        int error;

        if (byteswap)
                byteswap_uint64_array(lr, sizeof (*lr));

        tx = dmu_tx_create(os);
        dmu_tx_hold_free(tx, lr->lr_doid, 0, DMU_OBJECT_END);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                return (error);
        }

        error = dmu_object_free(os, lr->lr_doid, tx);
        dmu_tx_commit(tx);

        return (error);
}

zil_replay_func_t *ztest_replay_vector[TX_MAX_TYPE] = {
        NULL,                   /* 0 no such transaction type */
        ztest_replay_create,    /* TX_CREATE */
        NULL,                   /* TX_MKDIR */
        NULL,                   /* TX_MKXATTR */
        NULL,                   /* TX_SYMLINK */
        ztest_replay_remove,    /* TX_REMOVE */
        NULL,                   /* TX_RMDIR */
        NULL,                   /* TX_LINK */
        NULL,                   /* TX_RENAME */
        NULL,                   /* TX_WRITE */
        NULL,                   /* TX_TRUNCATE */
        NULL,                   /* TX_SETATTR */
        NULL,                   /* TX_ACL */
};

/*
 * Verify that we can't destroy an active pool, create an existing pool,
 * or create a pool with a bad vdev spec.
 */
void
ztest_spa_create_destroy(ztest_args_t *za)
{
        int error;
        spa_t *spa;
        nvlist_t *nvroot;

        /*
         * Attempt to create using a bad file.
         */
        nvroot = make_vdev_root("/dev/bogus", NULL, 0, 0, 0, 0, 0, 1);
        error = spa_create("ztest_bad_file", nvroot, NULL, NULL, NULL);
        nvlist_free(nvroot);
        if (error != ENOENT)
                fatal(0, "spa_create(bad_file) = %d", error);

        /*
         * Attempt to create using a bad mirror.
         */
        nvroot = make_vdev_root("/dev/bogus", NULL, 0, 0, 0, 0, 2, 1);
        error = spa_create("ztest_bad_mirror", nvroot, NULL, NULL, NULL);
        nvlist_free(nvroot);
        if (error != ENOENT)
                fatal(0, "spa_create(bad_mirror) = %d", error);

        /*
         * Attempt to create an existing pool.  It shouldn't matter
         * what's in the nvroot; we should fail with EEXIST.
         */
        (void) rw_rdlock(&ztest_shared->zs_name_lock);
        nvroot = make_vdev_root("/dev/bogus", NULL, 0, 0, 0, 0, 0, 1);
        error = spa_create(za->za_pool, nvroot, NULL, NULL, NULL);
        nvlist_free(nvroot);
        if (error != EEXIST)
                fatal(0, "spa_create(whatever) = %d", error);

        error = spa_open(za->za_pool, &spa, FTAG);
        if (error)
                fatal(0, "spa_open() = %d", error);

        error = spa_destroy(za->za_pool);
        if (error != EBUSY)
                fatal(0, "spa_destroy() = %d", error);

        spa_close(spa, FTAG);
        (void) rw_unlock(&ztest_shared->zs_name_lock);
}

static vdev_t *
vdev_lookup_by_path(vdev_t *vd, const char *path)
{
        vdev_t *mvd;

        if (vd->vdev_path != NULL && strcmp(path, vd->vdev_path) == 0)
                return (vd);

        for (int c = 0; c < vd->vdev_children; c++)
                if ((mvd = vdev_lookup_by_path(vd->vdev_child[c], path)) !=
                    NULL)
                        return (mvd);

        return (NULL);
}

/*
 * Verify that vdev_add() works as expected.
 */
void
ztest_vdev_add_remove(ztest_args_t *za)
{
        spa_t *spa = za->za_spa;
        uint64_t leaves = MAX(zopt_mirrors, 1) * zopt_raidz;
        nvlist_t *nvroot;
        int error;

        (void) mutex_lock(&ztest_shared->zs_vdev_lock);

        spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);

        ztest_shared->zs_vdev_primaries =
            spa->spa_root_vdev->vdev_children * leaves;

        spa_config_exit(spa, SCL_VDEV, FTAG);

        /*
         * Make 1/4 of the devices be log devices.
         */
        nvroot = make_vdev_root(NULL, NULL, zopt_vdev_size, 0,
            ztest_random(4) == 0, zopt_raidz, zopt_mirrors, 1);

        error = spa_vdev_add(spa, nvroot);
        nvlist_free(nvroot);

        (void) mutex_unlock(&ztest_shared->zs_vdev_lock);

        if (error == ENOSPC)
                ztest_record_enospc("spa_vdev_add");
        else if (error != 0)
                fatal(0, "spa_vdev_add() = %d", error);
}

/*
 * Verify that adding/removing aux devices (l2arc, hot spare) works as expected.
 */
void
ztest_vdev_aux_add_remove(ztest_args_t *za)
{
        spa_t *spa = za->za_spa;
        vdev_t *rvd = spa->spa_root_vdev;
        spa_aux_vdev_t *sav;
        char *aux;
        uint64_t guid = 0;
        int error;

        if (ztest_random(2) == 0) {
                sav = &spa->spa_spares;
                aux = ZPOOL_CONFIG_SPARES;
        } else {
                sav = &spa->spa_l2cache;
                aux = ZPOOL_CONFIG_L2CACHE;
        }

        (void) mutex_lock(&ztest_shared->zs_vdev_lock);

        spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);

        if (sav->sav_count != 0 && ztest_random(4) == 0) {
                /*
                 * Pick a random device to remove.
                 */
                guid = sav->sav_vdevs[ztest_random(sav->sav_count)]->vdev_guid;
        } else {
                /*
                 * Find an unused device we can add.
                 */
                ztest_shared->zs_vdev_aux = 0;
                for (;;) {
                        char path[MAXPATHLEN];
                        int c;
                        (void) sprintf(path, ztest_aux_template, zopt_dir,
                            zopt_pool, aux, ztest_shared->zs_vdev_aux);
                        for (c = 0; c < sav->sav_count; c++)
                                if (strcmp(sav->sav_vdevs[c]->vdev_path,
                                    path) == 0)
                                        break;
                        if (c == sav->sav_count &&
                            vdev_lookup_by_path(rvd, path) == NULL)
                                break;
                        ztest_shared->zs_vdev_aux++;
                }
        }

        spa_config_exit(spa, SCL_VDEV, FTAG);

        if (guid == 0) {
                /*
                 * Add a new device.
                 */
                nvlist_t *nvroot = make_vdev_root(NULL, aux,
                    (zopt_vdev_size * 5) / 4, 0, 0, 0, 0, 1);
                error = spa_vdev_add(spa, nvroot);
                if (error != 0)
                        fatal(0, "spa_vdev_add(%p) = %d", nvroot, error);
                nvlist_free(nvroot);
        } else {
                /*
                 * Remove an existing device.  Sometimes, dirty its
                 * vdev state first to make sure we handle removal
                 * of devices that have pending state changes.
                 */
                if (ztest_random(2) == 0)
                        (void) vdev_online(spa, guid, 0, NULL);

                error = spa_vdev_remove(spa, guid, B_FALSE);
                if (error != 0 && error != EBUSY)
                        fatal(0, "spa_vdev_remove(%llu) = %d", guid, error);
        }

        (void) mutex_unlock(&ztest_shared->zs_vdev_lock);
}

/*
 * Verify that we can attach and detach devices.
 */
void
ztest_vdev_attach_detach(ztest_args_t *za)
{
        spa_t *spa = za->za_spa;
        spa_aux_vdev_t *sav = &spa->spa_spares;
        vdev_t *rvd = spa->spa_root_vdev;
        vdev_t *oldvd, *newvd, *pvd;
        nvlist_t *root;
        uint64_t leaves = MAX(zopt_mirrors, 1) * zopt_raidz;
        uint64_t leaf, top;
        uint64_t ashift = ztest_get_ashift();
        uint64_t oldguid, pguid;
        size_t oldsize, newsize;
        char oldpath[MAXPATHLEN], newpath[MAXPATHLEN];
        int replacing;
        int oldvd_has_siblings = B_FALSE;
        int newvd_is_spare = B_FALSE;
        int oldvd_is_log;
        int error, expected_error;

        (void) mutex_lock(&ztest_shared->zs_vdev_lock);

        spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);

        /*
         * Decide whether to do an attach or a replace.
         */
        replacing = ztest_random(2);

        /*
         * Pick a random top-level vdev.
         */
        top = ztest_random(rvd->vdev_children);

        /*
         * Pick a random leaf within it.
         */
        leaf = ztest_random(leaves);

        /*
         * Locate this vdev.
         */
        oldvd = rvd->vdev_child[top];
        if (zopt_mirrors >= 1) {
                ASSERT(oldvd->vdev_ops == &vdev_mirror_ops);
                ASSERT(oldvd->vdev_children >= zopt_mirrors);
                oldvd = oldvd->vdev_child[leaf / zopt_raidz];
        }
        if (zopt_raidz > 1) {
                ASSERT(oldvd->vdev_ops == &vdev_raidz_ops);
                ASSERT(oldvd->vdev_children == zopt_raidz);
                oldvd = oldvd->vdev_child[leaf % zopt_raidz];
        }

        /*
         * If we're already doing an attach or replace, oldvd may be a
         * mirror vdev -- in which case, pick a random child.
         */
        while (oldvd->vdev_children != 0) {
                oldvd_has_siblings = B_TRUE;
                ASSERT(oldvd->vdev_children >= 2);
                oldvd = oldvd->vdev_child[ztest_random(oldvd->vdev_children)];
        }

        oldguid = oldvd->vdev_guid;
        oldsize = vdev_get_min_asize(oldvd);
        oldvd_is_log = oldvd->vdev_top->vdev_islog;
        (void) strcpy(oldpath, oldvd->vdev_path);
        pvd = oldvd->vdev_parent;
        pguid = pvd->vdev_guid;

        /*
         * If oldvd has siblings, then half of the time, detach it.
         */
        if (oldvd_has_siblings && ztest_random(2) == 0) {
                spa_config_exit(spa, SCL_VDEV, FTAG);
                error = spa_vdev_detach(spa, oldguid, pguid, B_FALSE);
                if (error != 0 && error != ENODEV && error != EBUSY &&
                    error != ENOTSUP)
                        fatal(0, "detach (%s) returned %d", oldpath, error);
                (void) mutex_unlock(&ztest_shared->zs_vdev_lock);
                return;
        }

        /*
         * For the new vdev, choose with equal probability between the two
         * standard paths (ending in either 'a' or 'b') or a random hot spare.
         */
        if (sav->sav_count != 0 && ztest_random(3) == 0) {
                newvd = sav->sav_vdevs[ztest_random(sav->sav_count)];
                newvd_is_spare = B_TRUE;
                (void) strcpy(newpath, newvd->vdev_path);
        } else {
                (void) snprintf(newpath, sizeof (newpath), ztest_dev_template,
                    zopt_dir, zopt_pool, top * leaves + leaf);
                if (ztest_random(2) == 0)
                        newpath[strlen(newpath) - 1] = 'b';
                newvd = vdev_lookup_by_path(rvd, newpath);
        }

        if (newvd) {
                newsize = vdev_get_min_asize(newvd);
        } else {
                /*
                 * Make newsize a little bigger or smaller than oldsize.
                 * If it's smaller, the attach should fail.
                 * If it's larger, and we're doing a replace,
                 * we should get dynamic LUN growth when we're done.
                 */
                newsize = 10 * oldsize / (9 + ztest_random(3));
        }

        /*
         * If pvd is not a mirror or root, the attach should fail with ENOTSUP,
         * unless it's a replace; in that case any non-replacing parent is OK.
         *
         * If newvd is already part of the pool, it should fail with EBUSY.
         *
         * If newvd is too small, it should fail with EOVERFLOW.
         */
        if (pvd->vdev_ops != &vdev_mirror_ops &&
            pvd->vdev_ops != &vdev_root_ops && (!replacing ||
            pvd->vdev_ops == &vdev_replacing_ops ||
            pvd->vdev_ops == &vdev_spare_ops))
                expected_error = ENOTSUP;
        else if (newvd_is_spare && (!replacing || oldvd_is_log))
                expected_error = ENOTSUP;
        else if (newvd == oldvd)
                expected_error = replacing ? 0 : EBUSY;
        else if (vdev_lookup_by_path(rvd, newpath) != NULL)
                expected_error = EBUSY;
        else if (newsize < oldsize)
                expected_error = EOVERFLOW;
        else if (ashift > oldvd->vdev_top->vdev_ashift)
                expected_error = EDOM;
        else
                expected_error = 0;

        spa_config_exit(spa, SCL_VDEV, FTAG);

        /*
         * Build the nvlist describing newpath.
         */
        root = make_vdev_root(newpath, NULL, newvd == NULL ? newsize : 0,
            ashift, 0, 0, 0, 1);

        error = spa_vdev_attach(spa, oldguid, root, replacing);

        nvlist_free(root);

        /*
         * If our parent was the replacing vdev, but the replace completed,
         * then instead of failing with ENOTSUP we may either succeed,
         * fail with ENODEV, or fail with EOVERFLOW.
         */
        if (expected_error == ENOTSUP &&
            (error == 0 || error == ENODEV || error == EOVERFLOW))
                expected_error = error;

        /*
         * If someone grew the LUN, the replacement may be too small.
         */
        if (error == EOVERFLOW || error == EBUSY)
                expected_error = error;

        /* XXX workaround 6690467 */
        if (error != expected_error && expected_error != EBUSY) {
                fatal(0, "attach (%s %llu, %s %llu, %d) "
                    "returned %d, expected %d",
                    oldpath, (longlong_t)oldsize, newpath,
                    (longlong_t)newsize, replacing, error, expected_error);
        }

        (void) mutex_unlock(&ztest_shared->zs_vdev_lock);
}

/*
 * Callback function which expands the physical size of the vdev.
 */
vdev_t *
grow_vdev(vdev_t *vd, void *arg)
{
        spa_t *spa = vd->vdev_spa;
        size_t *newsize = arg;
        size_t fsize;
        int fd;

        ASSERT(spa_config_held(spa, SCL_STATE, RW_READER) == SCL_STATE);
        ASSERT(vd->vdev_ops->vdev_op_leaf);

        if ((fd = open(vd->vdev_path, O_RDWR)) == -1)
                return (vd);

        fsize = lseek(fd, 0, SEEK_END);
        (void) ftruncate(fd, *newsize);

        if (zopt_verbose >= 6) {
                (void) printf("%s grew from %lu to %lu bytes\n",
                    vd->vdev_path, (ulong_t)fsize, (ulong_t)*newsize);
        }
        (void) close(fd);
        return (NULL);
}

/*
 * Callback function which expands a given vdev by calling vdev_online().
 */
/* ARGSUSED */
vdev_t *
online_vdev(vdev_t *vd, void *arg)
{
        spa_t *spa = vd->vdev_spa;
        vdev_t *tvd = vd->vdev_top;
        vdev_t *pvd = vd->vdev_parent;
        uint64_t guid = vd->vdev_guid;

        ASSERT(spa_config_held(spa, SCL_STATE, RW_READER) == SCL_STATE);
        ASSERT(vd->vdev_ops->vdev_op_leaf);

        /* Calling vdev_online will initialize the new metaslabs */
        spa_config_exit(spa, SCL_STATE, spa);
        (void) vdev_online(spa, guid, ZFS_ONLINE_EXPAND, NULL);
        spa_config_enter(spa, SCL_STATE, spa, RW_READER);

        /*
         * Since we dropped the lock we need to ensure that we're
         * still talking to the original vdev. It's possible this
         * vdev may have been detached/replaced while we were
         * trying to online it.
         */
        if (vd != vdev_lookup_by_guid(tvd, guid) || vd->vdev_parent != pvd) {
                if (zopt_verbose >= 6) {
                        (void) printf("vdev %p has disappeared, was "
                            "guid %llu\n", (void *)vd, (u_longlong_t)guid);
                }
                return (vd);
        }
        return (NULL);
}

/*
 * Traverse the vdev tree calling the supplied function.
 * We continue to walk the tree until we either have walked all
 * children or we receive a non-NULL return from the callback.
 * If a NULL callback is passed, then we just return back the first
 * leaf vdev we encounter.
 */
vdev_t *
vdev_walk_tree(vdev_t *vd, vdev_t *(*func)(vdev_t *, void *), void *arg)
{
        if (vd->vdev_ops->vdev_op_leaf) {
                if (func == NULL)
                        return (vd);
                else
                        return (func(vd, arg));
        }

        for (uint_t c = 0; c < vd->vdev_children; c++) {
                vdev_t *cvd = vd->vdev_child[c];
                if ((cvd = vdev_walk_tree(cvd, func, arg)) != NULL)
                        return (cvd);
        }
        return (NULL);
}

/*
 * Verify that dynamic LUN growth works as expected.
 */
void
ztest_vdev_LUN_growth(ztest_args_t *za)
{
        spa_t *spa = za->za_spa;
        vdev_t *vd, *tvd = NULL;
        size_t psize, newsize;
        uint64_t spa_newsize, spa_cursize, ms_count;

        (void) mutex_lock(&ztest_shared->zs_vdev_lock);
        mutex_enter(&spa_namespace_lock);
        spa_config_enter(spa, SCL_STATE, spa, RW_READER);

        while (tvd == NULL || tvd->vdev_islog) {
                uint64_t vdev;

                vdev = ztest_random(spa->spa_root_vdev->vdev_children);
                tvd = spa->spa_root_vdev->vdev_child[vdev];
        }

        /*
         * Determine the size of the first leaf vdev associated with
         * our top-level device.
         */
        vd = vdev_walk_tree(tvd, NULL, NULL);
        ASSERT3P(vd, !=, NULL);
        ASSERT(vd->vdev_ops->vdev_op_leaf);

        psize = vd->vdev_psize;

        /*
         * We only try to expand the vdev if it's less than 4x its
         * original size and it has a valid psize.
         */
        if (psize == 0 || psize >= 4 * zopt_vdev_size) {
                spa_config_exit(spa, SCL_STATE, spa);
                mutex_exit(&spa_namespace_lock);
                (void) mutex_unlock(&ztest_shared->zs_vdev_lock);
                return;
        }
        ASSERT(psize > 0);
        newsize = psize + psize / 8;
        ASSERT3U(newsize, >, psize);

        if (zopt_verbose >= 6) {
                (void) printf("Expanding vdev %s from %lu to %lu\n",
                    vd->vdev_path, (ulong_t)psize, (ulong_t)newsize);
        }

        spa_cursize = spa_get_space(spa);
        ms_count = tvd->vdev_ms_count;

        /*
         * Growing the vdev is a two step process:
         *      1). expand the physical size (i.e. relabel)
         *      2). online the vdev to create the new metaslabs
         */
        if (vdev_walk_tree(tvd, grow_vdev, &newsize) != NULL ||
            vdev_walk_tree(tvd, online_vdev, NULL) != NULL ||
            tvd->vdev_state != VDEV_STATE_HEALTHY) {
                if (zopt_verbose >= 5) {
                        (void) printf("Could not expand LUN because "
                            "some vdevs were not healthy\n");
                }
                (void) spa_config_exit(spa, SCL_STATE, spa);
                mutex_exit(&spa_namespace_lock);
                (void) mutex_unlock(&ztest_shared->zs_vdev_lock);
                return;
        }

        (void) spa_config_exit(spa, SCL_STATE, spa);
        mutex_exit(&spa_namespace_lock);

        /*
         * Expanding the LUN will update the config asynchronously,
         * thus we must wait for the async thread to complete any
         * pending tasks before proceeding.
         */
        mutex_enter(&spa->spa_async_lock);
        while (spa->spa_async_thread != NULL || spa->spa_async_tasks)
                cv_wait(&spa->spa_async_cv, &spa->spa_async_lock);
        mutex_exit(&spa->spa_async_lock);

        spa_config_enter(spa, SCL_STATE, spa, RW_READER);
        spa_newsize = spa_get_space(spa);

        /*
         * Make sure we were able to grow the pool.
         */
        if (ms_count >= tvd->vdev_ms_count ||
            spa_cursize >= spa_newsize) {
                (void) printf("Top-level vdev metaslab count: "
                    "before %llu, after %llu\n",
                    (u_longlong_t)ms_count,
                    (u_longlong_t)tvd->vdev_ms_count);
                fatal(0, "LUN expansion failed: before %llu, "
                    "after %llu\n", spa_cursize, spa_newsize);
        } else if (zopt_verbose >= 5) {
                char oldnumbuf[6], newnumbuf[6];

                nicenum(spa_cursize, oldnumbuf);
                nicenum(spa_newsize, newnumbuf);
                (void) printf("%s grew from %s to %s\n",
                    spa->spa_name, oldnumbuf, newnumbuf);
        }
        spa_config_exit(spa, SCL_STATE, spa);
        (void) mutex_unlock(&ztest_shared->zs_vdev_lock);
}

/* ARGSUSED */
static void
ztest_create_cb(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx)
{
        /*
         * Create the directory object.
         */
        VERIFY(dmu_object_claim(os, ZTEST_DIROBJ,
            DMU_OT_UINT64_OTHER, ZTEST_DIROBJ_BLOCKSIZE,
            DMU_OT_UINT64_OTHER, 5 * sizeof (ztest_block_tag_t), tx) == 0);

        VERIFY(zap_create_claim(os, ZTEST_MICROZAP_OBJ,
            DMU_OT_ZAP_OTHER, DMU_OT_NONE, 0, tx) == 0);

        VERIFY(zap_create_claim(os, ZTEST_FATZAP_OBJ,
            DMU_OT_ZAP_OTHER, DMU_OT_NONE, 0, tx) == 0);
}

static int
ztest_destroy_cb(char *name, void *arg)
{
        ztest_args_t *za = arg;
        objset_t *os;
        dmu_object_info_t *doi = &za->za_doi;
        int error;

        /*
         * Verify that the dataset contains a directory object.
         */
        error = dmu_objset_open(name, DMU_OST_OTHER,
            DS_MODE_USER | DS_MODE_READONLY, &os);
        ASSERT3U(error, ==, 0);
        error = dmu_object_info(os, ZTEST_DIROBJ, doi);
        if (error != ENOENT) {
                /* We could have crashed in the middle of destroying it */
                ASSERT3U(error, ==, 0);
                ASSERT3U(doi->doi_type, ==, DMU_OT_UINT64_OTHER);
                ASSERT3S(doi->doi_physical_blks, >=, 0);
        }
        dmu_objset_close(os);

        /*
         * Destroy the dataset.
         */
        error = dmu_objset_destroy(name, B_FALSE);
        if (error) {
                (void) dmu_objset_open(name, DMU_OST_OTHER,
                    DS_MODE_USER | DS_MODE_READONLY, &os);
                fatal(0, "dmu_objset_destroy(os=%p) = %d\n", &os, error);
        }
        return (0);
}

/*
 * Verify that dmu_objset_{create,destroy,open,close} work as expected.
 */
static uint64_t
ztest_log_create(zilog_t *zilog, dmu_tx_t *tx, uint64_t object, int mode)
{
        itx_t *itx;
        lr_create_t *lr;
        size_t namesize;
        char name[24];

        (void) sprintf(name, "ZOBJ_%llu", (u_longlong_t)object);
        namesize = strlen(name) + 1;

        itx = zil_itx_create(TX_CREATE, sizeof (*lr) + namesize +
            ztest_random(ZIL_MAX_BLKSZ));
        lr = (lr_create_t *)&itx->itx_lr;
        bzero(lr + 1, lr->lr_common.lrc_reclen - sizeof (*lr));
        lr->lr_doid = object;
        lr->lr_foid = 0;
        lr->lr_mode = mode;
        lr->lr_uid = 0;
        lr->lr_gid = 0;
        lr->lr_gen = dmu_tx_get_txg(tx);
        lr->lr_crtime[0] = time(NULL);
        lr->lr_crtime[1] = 0;
        lr->lr_rdev = 0;
        bcopy(name, (char *)(lr + 1), namesize);

        return (zil_itx_assign(zilog, itx, tx));
}

void
ztest_dmu_objset_create_destroy(ztest_args_t *za)
{
        int error;
        objset_t *os, *os2;
        char name[100];
        int basemode, expected_error;
        zilog_t *zilog;
        uint64_t seq;
        uint64_t objects;

        (void) rw_rdlock(&ztest_shared->zs_name_lock);
        (void) snprintf(name, 100, "%s/%s_temp_%llu", za->za_pool, za->za_pool,
            (u_longlong_t)za->za_instance);

        basemode = DS_MODE_TYPE(za->za_instance);
        if (basemode != DS_MODE_USER && basemode != DS_MODE_OWNER)
                basemode = DS_MODE_USER;

        /*
         * If this dataset exists from a previous run, process its replay log
         * half of the time.  If we don't replay it, then dmu_objset_destroy()
         * (invoked from ztest_destroy_cb() below) should just throw it away.
         */
        if (ztest_random(2) == 0 &&
            dmu_objset_open(name, DMU_OST_OTHER, DS_MODE_OWNER, &os) == 0) {
                zil_replay(os, os, ztest_replay_vector);
                dmu_objset_close(os);
        }

        /*
         * There may be an old instance of the dataset we're about to
         * create lying around from a previous run.  If so, destroy it
         * and all of its snapshots.
         */
        (void) dmu_objset_find(name, ztest_destroy_cb, za,
            DS_FIND_CHILDREN | DS_FIND_SNAPSHOTS);

        /*
         * Verify that the destroyed dataset is no longer in the namespace.
         */
        error = dmu_objset_open(name, DMU_OST_OTHER, basemode, &os);
        if (error != ENOENT)
                fatal(1, "dmu_objset_open(%s) found destroyed dataset %p",
                    name, os);

        /*
         * Verify that we can create a new dataset.
         */
        error = dmu_objset_create(name, DMU_OST_OTHER, NULL, 0,
            ztest_create_cb, NULL);
        if (error) {
                if (error == ENOSPC) {
                        ztest_record_enospc("dmu_objset_create");
                        (void) rw_unlock(&ztest_shared->zs_name_lock);
                        return;
                }
                fatal(0, "dmu_objset_create(%s) = %d", name, error);
        }

        error = dmu_objset_open(name, DMU_OST_OTHER, basemode, &os);
        if (error) {
                fatal(0, "dmu_objset_open(%s) = %d", name, error);
        }

        /*
         * Open the intent log for it.
         */
        zilog = zil_open(os, NULL);

        /*
         * Put a random number of objects in there.
         */
        objects = ztest_random(20);
        seq = 0;
        while (objects-- != 0) {
                uint64_t object;
                dmu_tx_t *tx = dmu_tx_create(os);
                dmu_tx_hold_write(tx, DMU_NEW_OBJECT, 0, sizeof (name));
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        dmu_tx_abort(tx);
                } else {
                        object = dmu_object_alloc(os, DMU_OT_UINT64_OTHER, 0,
                            DMU_OT_NONE, 0, tx);
                        ztest_set_random_blocksize(os, object, tx);
                        seq = ztest_log_create(zilog, tx, object,
                            DMU_OT_UINT64_OTHER);
                        dmu_write(os, object, 0, sizeof (name), name, tx);
                        dmu_tx_commit(tx);
                }
                if (ztest_random(5) == 0) {
                        zil_commit(zilog, seq, object);
                }
                if (ztest_random(100) == 0) {
                        error = zil_suspend(zilog);
                        if (error == 0) {
                                zil_resume(zilog);
                        }
                }
        }

        /*
         * Verify that we cannot create an existing dataset.
         */
        error = dmu_objset_create(name, DMU_OST_OTHER, NULL, 0, NULL, NULL);
        if (error != EEXIST)
                fatal(0, "created existing dataset, error = %d", error);

        /*
         * Verify that multiple dataset holds are allowed, but only when
         * the new access mode is compatible with the base mode.
         */
        if (basemode == DS_MODE_OWNER) {
                error = dmu_objset_open(name, DMU_OST_OTHER, DS_MODE_USER,
                    &os2);
                if (error)
                        fatal(0, "dmu_objset_open('%s') = %d", name, error);
                else
                        dmu_objset_close(os2);
        }
        error = dmu_objset_open(name, DMU_OST_OTHER, DS_MODE_OWNER, &os2);
        expected_error = (basemode == DS_MODE_OWNER) ? EBUSY : 0;
        if (error != expected_error)
                fatal(0, "dmu_objset_open('%s') = %d, expected %d",
                    name, error, expected_error);
        if (error == 0)
                dmu_objset_close(os2);

        zil_close(zilog);
        dmu_objset_close(os);

        error = dmu_objset_destroy(name, B_FALSE);
        if (error)
                fatal(0, "dmu_objset_destroy(%s) = %d", name, error);

        (void) rw_unlock(&ztest_shared->zs_name_lock);
}

/*
 * Verify that dmu_snapshot_{create,destroy,open,close} work as expected.
 */
void
ztest_dmu_snapshot_create_destroy(ztest_args_t *za)
{
        int error;
        objset_t *os = za->za_os;
        char snapname[100];
        char osname[MAXNAMELEN];

        (void) rw_rdlock(&ztest_shared->zs_name_lock);
        dmu_objset_name(os, osname);
        (void) snprintf(snapname, 100, "%s@%llu", osname,
            (u_longlong_t)za->za_instance);

        error = dmu_objset_destroy(snapname, B_FALSE);
        if (error != 0 && error != ENOENT)
                fatal(0, "dmu_objset_destroy() = %d", error);
        error = dmu_objset_snapshot(osname, strchr(snapname, '@')+1,
            NULL, FALSE);
        if (error == ENOSPC)
                ztest_record_enospc("dmu_take_snapshot");
        else if (error != 0 && error != EEXIST)
                fatal(0, "dmu_take_snapshot() = %d", error);
        (void) rw_unlock(&ztest_shared->zs_name_lock);
}

/*
 * Cleanup non-standard snapshots and clones.
 */
void
ztest_dsl_dataset_cleanup(char *osname, uint64_t curval)
{
        char snap1name[100];
        char clone1name[100];
        char snap2name[100];
        char clone2name[100];
        char snap3name[100];
        int error;

        (void) snprintf(snap1name, 100, "%s@s1_%llu", osname, curval);
        (void) snprintf(clone1name, 100, "%s/c1_%llu", osname, curval);
        (void) snprintf(snap2name, 100, "%s@s2_%llu", clone1name, curval);
        (void) snprintf(clone2name, 100, "%s/c2_%llu", osname, curval);
        (void) snprintf(snap3name, 100, "%s@s3_%llu", clone1name, curval);

        error = dmu_objset_destroy(clone2name, B_FALSE);
        if (error && error != ENOENT)
                fatal(0, "dmu_objset_destroy(%s) = %d", clone2name, error);
        error = dmu_objset_destroy(snap3name, B_FALSE);
        if (error && error != ENOENT)
                fatal(0, "dmu_objset_destroy(%s) = %d", snap3name, error);
        error = dmu_objset_destroy(snap2name, B_FALSE);
        if (error && error != ENOENT)
                fatal(0, "dmu_objset_destroy(%s) = %d", snap2name, error);
        error = dmu_objset_destroy(clone1name, B_FALSE);
        if (error && error != ENOENT)
                fatal(0, "dmu_objset_destroy(%s) = %d", clone1name, error);
        error = dmu_objset_destroy(snap1name, B_FALSE);
        if (error && error != ENOENT)
                fatal(0, "dmu_objset_destroy(%s) = %d", snap1name, error);
}

/*
 * Verify dsl_dataset_promote handles EBUSY
 */
void
ztest_dsl_dataset_promote_busy(ztest_args_t *za)
{
        int error;
        objset_t *os = za->za_os;
        objset_t *clone;
        dsl_dataset_t *ds;
        char snap1name[100];
        char clone1name[100];
        char snap2name[100];
        char clone2name[100];
        char snap3name[100];
        char osname[MAXNAMELEN];
        uint64_t curval = za->za_instance;

        (void) rw_rdlock(&ztest_shared->zs_name_lock);

        dmu_objset_name(os, osname);
        ztest_dsl_dataset_cleanup(osname, curval);

        (void) snprintf(snap1name, 100, "%s@s1_%llu", osname, curval);
        (void) snprintf(clone1name, 100, "%s/c1_%llu", osname, curval);
        (void) snprintf(snap2name, 100, "%s@s2_%llu", clone1name, curval);
        (void) snprintf(clone2name, 100, "%s/c2_%llu", osname, curval);
        (void) snprintf(snap3name, 100, "%s@s3_%llu", clone1name, curval);

        error = dmu_objset_snapshot(osname, strchr(snap1name, '@')+1,
            NULL, FALSE);
        if (error && error != EEXIST) {
                if (error == ENOSPC) {
                        ztest_record_enospc("dmu_take_snapshot");
                        goto out;
                }
                fatal(0, "dmu_take_snapshot(%s) = %d", snap1name, error);
        }

        error = dmu_objset_open(snap1name, DMU_OST_OTHER,
            DS_MODE_USER | DS_MODE_READONLY, &clone);
        if (error)
                fatal(0, "dmu_open_snapshot(%s) = %d", snap1name, error);

        error = dmu_objset_create(clone1name, DMU_OST_OTHER, clone, 0,
            NULL, NULL);
        dmu_objset_close(clone);
        if (error) {
                if (error == ENOSPC) {
                        ztest_record_enospc("dmu_objset_create");
                        goto out;
                }
                fatal(0, "dmu_objset_create(%s) = %d", clone1name, error);
        }

        error = dmu_objset_snapshot(clone1name, strchr(snap2name, '@')+1,
            NULL, FALSE);
        if (error && error != EEXIST) {
                if (error == ENOSPC) {
                        ztest_record_enospc("dmu_take_snapshot");
                        goto out;
                }
                fatal(0, "dmu_open_snapshot(%s) = %d", snap2name, error);
        }

        error = dmu_objset_snapshot(clone1name, strchr(snap3name, '@')+1,
            NULL, FALSE);
        if (error && error != EEXIST) {
                if (error == ENOSPC) {
                        ztest_record_enospc("dmu_take_snapshot");
                        goto out;
                }
                fatal(0, "dmu_open_snapshot(%s) = %d", snap3name, error);
        }

        error = dmu_objset_open(snap3name, DMU_OST_OTHER,
            DS_MODE_USER | DS_MODE_READONLY, &clone);
        if (error)
                fatal(0, "dmu_open_snapshot(%s) = %d", snap3name, error);

        error = dmu_objset_create(clone2name, DMU_OST_OTHER, clone, 0,
            NULL, NULL);
        dmu_objset_close(clone);
        if (error) {
                if (error == ENOSPC) {
                        ztest_record_enospc("dmu_objset_create");
                        goto out;
                }
                fatal(0, "dmu_objset_create(%s) = %d", clone2name, error);
        }

        error = dsl_dataset_own(snap1name, DS_MODE_READONLY, FTAG, &ds);
        if (error)
                fatal(0, "dsl_dataset_own(%s) = %d", snap1name, error);
        error = dsl_dataset_promote(clone2name);
        if (error != EBUSY)
                fatal(0, "dsl_dataset_promote(%s), %d, not EBUSY", clone2name,
                    error);
        dsl_dataset_disown(ds, FTAG);

out:
        ztest_dsl_dataset_cleanup(osname, curval);

        (void) rw_unlock(&ztest_shared->zs_name_lock);
}

/*
 * Verify that dmu_object_{alloc,free} work as expected.
 */
void
ztest_dmu_object_alloc_free(ztest_args_t *za)
{
        objset_t *os = za->za_os;
        dmu_buf_t *db;
        dmu_tx_t *tx;
        uint64_t batchobj, object, batchsize, endoff, temp;
        int b, c, error, bonuslen;
        dmu_object_info_t *doi = &za->za_doi;
        char osname[MAXNAMELEN];

        dmu_objset_name(os, osname);

        endoff = -8ULL;
        batchsize = 2;

        /*
         * Create a batch object if necessary, and record it in the directory.
         */
        VERIFY3U(0, ==, dmu_read(os, ZTEST_DIROBJ, za->za_diroff,
            sizeof (uint64_t), &batchobj, DMU_READ_PREFETCH));
        if (batchobj == 0) {
                tx = dmu_tx_create(os);
                dmu_tx_hold_write(tx, ZTEST_DIROBJ, za->za_diroff,
                    sizeof (uint64_t));
                dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        ztest_record_enospc("create a batch object");
                        dmu_tx_abort(tx);
                        return;
                }
                batchobj = dmu_object_alloc(os, DMU_OT_UINT64_OTHER, 0,
                    DMU_OT_NONE, 0, tx);
                ztest_set_random_blocksize(os, batchobj, tx);
                dmu_write(os, ZTEST_DIROBJ, za->za_diroff,
                    sizeof (uint64_t), &batchobj, tx);
                dmu_tx_commit(tx);
        }

        /*
         * Destroy the previous batch of objects.
         */
        for (b = 0; b < batchsize; b++) {
                VERIFY3U(0, ==, dmu_read(os, batchobj, b * sizeof (uint64_t),
                    sizeof (uint64_t), &object, DMU_READ_PREFETCH));
                if (object == 0)
                        continue;
                /*
                 * Read and validate contents.
                 * We expect the nth byte of the bonus buffer to be n.
                 */
                VERIFY(0 == dmu_bonus_hold(os, object, FTAG, &db));
                za->za_dbuf = db;

                dmu_object_info_from_db(db, doi);
                ASSERT(doi->doi_type == DMU_OT_UINT64_OTHER);
                ASSERT(doi->doi_bonus_type == DMU_OT_PLAIN_OTHER);
                ASSERT3S(doi->doi_physical_blks, >=, 0);

                bonuslen = doi->doi_bonus_size;

                for (c = 0; c < bonuslen; c++) {
                        if (((uint8_t *)db->db_data)[c] !=
                            (uint8_t)(c + bonuslen)) {
                                fatal(0,
                                    "bad bonus: %s, obj %llu, off %d: %u != %u",
                                    osname, object, c,
                                    ((uint8_t *)db->db_data)[c],
                                    (uint8_t)(c + bonuslen));
                        }
                }

                dmu_buf_rele(db, FTAG);
                za->za_dbuf = NULL;

                /*
                 * We expect the word at endoff to be our object number.
                 */
                VERIFY(0 == dmu_read(os, object, endoff,
                    sizeof (uint64_t), &temp, DMU_READ_PREFETCH));

                if (temp != object) {
                        fatal(0, "bad data in %s, got %llu, expected %llu",
                            osname, temp, object);
                }

                /*
                 * Destroy old object and clear batch entry.
                 */
                tx = dmu_tx_create(os);
                dmu_tx_hold_write(tx, batchobj,
                    b * sizeof (uint64_t), sizeof (uint64_t));
                dmu_tx_hold_free(tx, object, 0, DMU_OBJECT_END);
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        ztest_record_enospc("free object");
                        dmu_tx_abort(tx);
                        return;
                }
                error = dmu_object_free(os, object, tx);
                if (error) {
                        fatal(0, "dmu_object_free('%s', %llu) = %d",
                            osname, object, error);
                }
                object = 0;

                dmu_object_set_checksum(os, batchobj,
                    ztest_random_checksum(), tx);
                dmu_object_set_compress(os, batchobj,
                    ztest_random_compress(), tx);

                dmu_write(os, batchobj, b * sizeof (uint64_t),
                    sizeof (uint64_t), &object, tx);

                dmu_tx_commit(tx);
        }

        /*
         * Before creating the new batch of objects, generate a bunch of churn.
         */
        for (b = ztest_random(100); b > 0; b--) {
                tx = dmu_tx_create(os);
                dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        ztest_record_enospc("churn objects");
                        dmu_tx_abort(tx);
                        return;
                }
                object = dmu_object_alloc(os, DMU_OT_UINT64_OTHER, 0,
                    DMU_OT_NONE, 0, tx);
                ztest_set_random_blocksize(os, object, tx);
                error = dmu_object_free(os, object, tx);
                if (error) {
                        fatal(0, "dmu_object_free('%s', %llu) = %d",
                            osname, object, error);
                }
                dmu_tx_commit(tx);
        }

        /*
         * Create a new batch of objects with randomly chosen
         * blocksizes and record them in the batch directory.
         */
        for (b = 0; b < batchsize; b++) {
                uint32_t va_blksize;
                u_longlong_t va_nblocks;

                tx = dmu_tx_create(os);
                dmu_tx_hold_write(tx, batchobj, b * sizeof (uint64_t),
                    sizeof (uint64_t));
                dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
                dmu_tx_hold_write(tx, DMU_NEW_OBJECT, endoff,
                    sizeof (uint64_t));
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        ztest_record_enospc("create batchobj");
                        dmu_tx_abort(tx);
                        return;
                }
                bonuslen = (int)ztest_random(dmu_bonus_max()) + 1;

                object = dmu_object_alloc(os, DMU_OT_UINT64_OTHER, 0,
                    DMU_OT_PLAIN_OTHER, bonuslen, tx);

                ztest_set_random_blocksize(os, object, tx);

                dmu_object_set_checksum(os, object,
                    ztest_random_checksum(), tx);
                dmu_object_set_compress(os, object,
                    ztest_random_compress(), tx);

                dmu_write(os, batchobj, b * sizeof (uint64_t),
                    sizeof (uint64_t), &object, tx);

                /*
                 * Write to both the bonus buffer and the regular data.
                 */
                VERIFY(dmu_bonus_hold(os, object, FTAG, &db) == 0);
                za->za_dbuf = db;
                ASSERT3U(bonuslen, <=, db->db_size);

                dmu_object_size_from_db(db, &va_blksize, &va_nblocks);
                ASSERT3S(va_nblocks, >=, 0);

                dmu_buf_will_dirty(db, tx);

                /*
                 * See comments above regarding the contents of
                 * the bonus buffer and the word at endoff.
                 */
                for (c = 0; c < bonuslen; c++)
                        ((uint8_t *)db->db_data)[c] = (uint8_t)(c + bonuslen);

                dmu_buf_rele(db, FTAG);
                za->za_dbuf = NULL;

                /*
                 * Write to a large offset to increase indirection.
                 */
                dmu_write(os, object, endoff, sizeof (uint64_t), &object, tx);

                dmu_tx_commit(tx);
        }
}

/*
 * Verify that dmu_{read,write} work as expected.
 */
typedef struct bufwad {
        uint64_t        bw_index;
        uint64_t        bw_txg;
        uint64_t        bw_data;
} bufwad_t;

typedef struct dmu_read_write_dir {
        uint64_t        dd_packobj;
        uint64_t        dd_bigobj;
        uint64_t        dd_chunk;
} dmu_read_write_dir_t;

void
ztest_dmu_read_write(ztest_args_t *za)
{
        objset_t *os = za->za_os;
        dmu_read_write_dir_t dd;
        dmu_tx_t *tx;
        int i, freeit, error;
        uint64_t n, s, txg;
        bufwad_t *packbuf, *bigbuf, *pack, *bigH, *bigT;
        uint64_t packoff, packsize, bigoff, bigsize;
        uint64_t regions = 997;
        uint64_t stride = 123456789ULL;
        uint64_t width = 40;
        int free_percent = 5;

        /*
         * This test uses two objects, packobj and bigobj, that are always
         * updated together (i.e. in the same tx) so that their contents are
         * in sync and can be compared.  Their contents relate to each other
         * in a simple way: packobj is a dense array of 'bufwad' structures,
         * while bigobj is a sparse array of the same bufwads.  Specifically,
         * for any index n, there are three bufwads that should be identical:
         *
         *      packobj, at offset n * sizeof (bufwad_t)
         *      bigobj, at the head of the nth chunk
         *      bigobj, at the tail of the nth chunk
         *
         * The chunk size is arbitrary. It doesn't have to be a power of two,
         * and it doesn't have any relation to the object blocksize.
         * The only requirement is that it can hold at least two bufwads.
         *
         * Normally, we write the bufwad to each of these locations.
         * However, free_percent of the time we instead write zeroes to
         * packobj and perform a dmu_free_range() on bigobj.  By comparing
         * bigobj to packobj, we can verify that the DMU is correctly
         * tracking which parts of an object are allocated and free,
         * and that the contents of the allocated blocks are correct.
         */

        /*
         * Read the directory info.  If it's the first time, set things up.
         */
        VERIFY(0 == dmu_read(os, ZTEST_DIROBJ, za->za_diroff,
            sizeof (dd), &dd, DMU_READ_PREFETCH));
        if (dd.dd_chunk == 0) {
                ASSERT(dd.dd_packobj == 0);
                ASSERT(dd.dd_bigobj == 0);
                tx = dmu_tx_create(os);
                dmu_tx_hold_write(tx, ZTEST_DIROBJ, za->za_diroff, sizeof (dd));
                dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        ztest_record_enospc("create r/w directory");
                        dmu_tx_abort(tx);
                        return;
                }

                dd.dd_packobj = dmu_object_alloc(os, DMU_OT_UINT64_OTHER, 0,
                    DMU_OT_NONE, 0, tx);
                dd.dd_bigobj = dmu_object_alloc(os, DMU_OT_UINT64_OTHER, 0,
                    DMU_OT_NONE, 0, tx);
                dd.dd_chunk = (1000 + ztest_random(1000)) * sizeof (uint64_t);

                ztest_set_random_blocksize(os, dd.dd_packobj, tx);
                ztest_set_random_blocksize(os, dd.dd_bigobj, tx);

                dmu_write(os, ZTEST_DIROBJ, za->za_diroff, sizeof (dd), &dd,
                    tx);
                dmu_tx_commit(tx);
        }

        /*
         * Prefetch a random chunk of the big object.
         * Our aim here is to get some async reads in flight
         * for blocks that we may free below; the DMU should
         * handle this race correctly.
         */
        n = ztest_random(regions) * stride + ztest_random(width);
        s = 1 + ztest_random(2 * width - 1);
        dmu_prefetch(os, dd.dd_bigobj, n * dd.dd_chunk, s * dd.dd_chunk);

        /*
         * Pick a random index and compute the offsets into packobj and bigobj.
         */
        n = ztest_random(regions) * stride + ztest_random(width);
        s = 1 + ztest_random(width - 1);

        packoff = n * sizeof (bufwad_t);
        packsize = s * sizeof (bufwad_t);

        bigoff = n * dd.dd_chunk;
        bigsize = s * dd.dd_chunk;

        packbuf = umem_alloc(packsize, UMEM_NOFAIL);
        bigbuf = umem_alloc(bigsize, UMEM_NOFAIL);

        /*
         * free_percent of the time, free a range of bigobj rather than
         * overwriting it.
         */
        freeit = (ztest_random(100) < free_percent);

        /*
         * Read the current contents of our objects.
         */
        error = dmu_read(os, dd.dd_packobj, packoff, packsize, packbuf,
            DMU_READ_PREFETCH);
        ASSERT3U(error, ==, 0);
        error = dmu_read(os, dd.dd_bigobj, bigoff, bigsize, bigbuf,
            DMU_READ_PREFETCH);
        ASSERT3U(error, ==, 0);

        /*
         * Get a tx for the mods to both packobj and bigobj.
         */
        tx = dmu_tx_create(os);

        dmu_tx_hold_write(tx, dd.dd_packobj, packoff, packsize);

        if (freeit)
                dmu_tx_hold_free(tx, dd.dd_bigobj, bigoff, bigsize);
        else
                dmu_tx_hold_write(tx, dd.dd_bigobj, bigoff, bigsize);

        error = dmu_tx_assign(tx, TXG_WAIT);

        if (error) {
                ztest_record_enospc("dmu r/w range");
                dmu_tx_abort(tx);
                umem_free(packbuf, packsize);
                umem_free(bigbuf, bigsize);
                return;
        }

        txg = dmu_tx_get_txg(tx);

        /*
         * For each index from n to n + s, verify that the existing bufwad
         * in packobj matches the bufwads at the head and tail of the
         * corresponding chunk in bigobj.  Then update all three bufwads
         * with the new values we want to write out.
         */
        for (i = 0; i < s; i++) {
                /* LINTED */
                pack = (bufwad_t *)((char *)packbuf + i * sizeof (bufwad_t));
                /* LINTED */
                bigH = (bufwad_t *)((char *)bigbuf + i * dd.dd_chunk);
                /* LINTED */
                bigT = (bufwad_t *)((char *)bigH + dd.dd_chunk) - 1;

                ASSERT((uintptr_t)bigH - (uintptr_t)bigbuf < bigsize);
                ASSERT((uintptr_t)bigT - (uintptr_t)bigbuf < bigsize);

                if (pack->bw_txg > txg)
                        fatal(0, "future leak: got %llx, open txg is %llx",
                            pack->bw_txg, txg);

                if (pack->bw_data != 0 && pack->bw_index != n + i)
                        fatal(0, "wrong index: got %llx, wanted %llx+%llx",
                            pack->bw_index, n, i);

                if (bcmp(pack, bigH, sizeof (bufwad_t)) != 0)
                        fatal(0, "pack/bigH mismatch in %p/%p", pack, bigH);

                if (bcmp(pack, bigT, sizeof (bufwad_t)) != 0)
                        fatal(0, "pack/bigT mismatch in %p/%p", pack, bigT);

                if (freeit) {
                        bzero(pack, sizeof (bufwad_t));
                } else {
                        pack->bw_index = n + i;
                        pack->bw_txg = txg;
                        pack->bw_data = 1 + ztest_random(-2ULL);
                }
                *bigH = *pack;
                *bigT = *pack;
        }

        /*
         * We've verified all the old bufwads, and made new ones.
         * Now write them out.
         */
        dmu_write(os, dd.dd_packobj, packoff, packsize, packbuf, tx);

        if (freeit) {
                if (zopt_verbose >= 6) {
                        (void) printf("freeing offset %llx size %llx"
                            " txg %llx\n",
                            (u_longlong_t)bigoff,
                            (u_longlong_t)bigsize,
                            (u_longlong_t)txg);
                }
                VERIFY(0 == dmu_free_range(os, dd.dd_bigobj, bigoff,
                    bigsize, tx));
        } else {
                if (zopt_verbose >= 6) {
                        (void) printf("writing offset %llx size %llx"
                            " txg %llx\n",
                            (u_longlong_t)bigoff,
                            (u_longlong_t)bigsize,
                            (u_longlong_t)txg);
                }
                dmu_write(os, dd.dd_bigobj, bigoff, bigsize, bigbuf, tx);
        }

        dmu_tx_commit(tx);

        /*
         * Sanity check the stuff we just wrote.
         */
        {
                void *packcheck = umem_alloc(packsize, UMEM_NOFAIL);
                void *bigcheck = umem_alloc(bigsize, UMEM_NOFAIL);

                VERIFY(0 == dmu_read(os, dd.dd_packobj, packoff,
                    packsize, packcheck, DMU_READ_PREFETCH));
                VERIFY(0 == dmu_read(os, dd.dd_bigobj, bigoff,
                    bigsize, bigcheck, DMU_READ_PREFETCH));

                ASSERT(bcmp(packbuf, packcheck, packsize) == 0);
                ASSERT(bcmp(bigbuf, bigcheck, bigsize) == 0);

                umem_free(packcheck, packsize);
                umem_free(bigcheck, bigsize);
        }

        umem_free(packbuf, packsize);
        umem_free(bigbuf, bigsize);
}

void
compare_and_update_pbbufs(uint64_t s, bufwad_t *packbuf, bufwad_t *bigbuf,
    uint64_t bigsize, uint64_t n, dmu_read_write_dir_t dd, uint64_t txg)
{
        uint64_t i;
        bufwad_t *pack;
        bufwad_t *bigH;
        bufwad_t *bigT;

        /*
         * For each index from n to n + s, verify that the existing bufwad
         * in packobj matches the bufwads at the head and tail of the
         * corresponding chunk in bigobj.  Then update all three bufwads
         * with the new values we want to write out.
         */
        for (i = 0; i < s; i++) {
                /* LINTED */
                pack = (bufwad_t *)((char *)packbuf + i * sizeof (bufwad_t));
                /* LINTED */
                bigH = (bufwad_t *)((char *)bigbuf + i * dd.dd_chunk);
                /* LINTED */
                bigT = (bufwad_t *)((char *)bigH + dd.dd_chunk) - 1;

                ASSERT((uintptr_t)bigH - (uintptr_t)bigbuf < bigsize);
                ASSERT((uintptr_t)bigT - (uintptr_t)bigbuf < bigsize);

                if (pack->bw_txg > txg)
                        fatal(0, "future leak: got %llx, open txg is %llx",
                            pack->bw_txg, txg);

                if (pack->bw_data != 0 && pack->bw_index != n + i)
                        fatal(0, "wrong index: got %llx, wanted %llx+%llx",
                            pack->bw_index, n, i);

                if (bcmp(pack, bigH, sizeof (bufwad_t)) != 0)
                        fatal(0, "pack/bigH mismatch in %p/%p", pack, bigH);

                if (bcmp(pack, bigT, sizeof (bufwad_t)) != 0)
                        fatal(0, "pack/bigT mismatch in %p/%p", pack, bigT);

                pack->bw_index = n + i;
                pack->bw_txg = txg;
                pack->bw_data = 1 + ztest_random(-2ULL);

                *bigH = *pack;
                *bigT = *pack;
        }
}

void
ztest_dmu_read_write_zcopy(ztest_args_t *za)
{
        objset_t *os = za->za_os;
        dmu_read_write_dir_t dd;
        dmu_tx_t *tx;
        uint64_t i;
        int error;
        uint64_t n, s, txg;
        bufwad_t *packbuf, *bigbuf;
        uint64_t packoff, packsize, bigoff, bigsize;
        uint64_t regions = 997;
        uint64_t stride = 123456789ULL;
        uint64_t width = 9;
        dmu_buf_t *bonus_db;
        arc_buf_t **bigbuf_arcbufs;
        dmu_object_info_t *doi = &za->za_doi;

        /*
         * This test uses two objects, packobj and bigobj, that are always
         * updated together (i.e. in the same tx) so that their contents are
         * in sync and can be compared.  Their contents relate to each other
         * in a simple way: packobj is a dense array of 'bufwad' structures,
         * while bigobj is a sparse array of the same bufwads.  Specifically,
         * for any index n, there are three bufwads that should be identical:
         *
         *      packobj, at offset n * sizeof (bufwad_t)
         *      bigobj, at the head of the nth chunk
         *      bigobj, at the tail of the nth chunk
         *
         * The chunk size is set equal to bigobj block size so that
         * dmu_assign_arcbuf() can be tested for object updates.
         */

        /*
         * Read the directory info.  If it's the first time, set things up.
         */
        VERIFY(0 == dmu_read(os, ZTEST_DIROBJ, za->za_diroff,
            sizeof (dd), &dd, DMU_READ_PREFETCH));
        if (dd.dd_chunk == 0) {
                ASSERT(dd.dd_packobj == 0);
                ASSERT(dd.dd_bigobj == 0);
                tx = dmu_tx_create(os);
                dmu_tx_hold_write(tx, ZTEST_DIROBJ, za->za_diroff, sizeof (dd));
                dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        ztest_record_enospc("create r/w directory");
                        dmu_tx_abort(tx);
                        return;
                }

                dd.dd_packobj = dmu_object_alloc(os, DMU_OT_UINT64_OTHER, 0,
                    DMU_OT_NONE, 0, tx);
                dd.dd_bigobj = dmu_object_alloc(os, DMU_OT_UINT64_OTHER, 0,
                    DMU_OT_NONE, 0, tx);
                ztest_set_random_blocksize(os, dd.dd_packobj, tx);
                ztest_set_random_blocksize(os, dd.dd_bigobj, tx);

                VERIFY(dmu_object_info(os, dd.dd_bigobj, doi) == 0);
                ASSERT(doi->doi_data_block_size >= 2 * sizeof (bufwad_t));
                ASSERT(ISP2(doi->doi_data_block_size));
                dd.dd_chunk = doi->doi_data_block_size;

                dmu_write(os, ZTEST_DIROBJ, za->za_diroff, sizeof (dd), &dd,
                    tx);
                dmu_tx_commit(tx);
        } else {
                VERIFY(dmu_object_info(os, dd.dd_bigobj, doi) == 0);
                VERIFY(ISP2(doi->doi_data_block_size));
                VERIFY(dd.dd_chunk == doi->doi_data_block_size);
                VERIFY(dd.dd_chunk >= 2 * sizeof (bufwad_t));
        }

        /*
         * Pick a random index and compute the offsets into packobj and bigobj.
         */
        n = ztest_random(regions) * stride + ztest_random(width);
        s = 1 + ztest_random(width - 1);

        packoff = n * sizeof (bufwad_t);
        packsize = s * sizeof (bufwad_t);

        bigoff = n * dd.dd_chunk;
        bigsize = s * dd.dd_chunk;

        packbuf = umem_zalloc(packsize, UMEM_NOFAIL);
        bigbuf = umem_zalloc(bigsize, UMEM_NOFAIL);

        VERIFY(dmu_bonus_hold(os, dd.dd_bigobj, FTAG, &bonus_db) == 0);

        bigbuf_arcbufs = umem_zalloc(2 * s * sizeof (arc_buf_t *), UMEM_NOFAIL);

        /*
         * Iteration 0 test zcopy for DB_UNCACHED dbufs.
         * Iteration 1 test zcopy to already referenced dbufs.
         * Iteration 2 test zcopy to dirty dbuf in the same txg.
         * Iteration 3 test zcopy to dbuf dirty in previous txg.
         * Iteration 4 test zcopy when dbuf is no longer dirty.
         * Iteration 5 test zcopy when it can't be done.
         * Iteration 6 one more zcopy write.
         */
        for (i = 0; i < 7; i++) {
                uint64_t j;
                uint64_t off;

                /*
                 * In iteration 5 (i == 5) use arcbufs
                 * that don't match bigobj blksz to test
                 * dmu_assign_arcbuf() when it can't directly
                 * assign an arcbuf to a dbuf.
                 */
                for (j = 0; j < s; j++) {
                        if (i != 5) {
                                bigbuf_arcbufs[j] =
                                    dmu_request_arcbuf(bonus_db,
                                    dd.dd_chunk);
                        } else {
                                bigbuf_arcbufs[2 * j] =
                                    dmu_request_arcbuf(bonus_db,
                                    dd.dd_chunk / 2);
                                bigbuf_arcbufs[2 * j + 1] =
                                    dmu_request_arcbuf(bonus_db,
                                    dd.dd_chunk / 2);
                        }
                }

                /*
                 * Get a tx for the mods to both packobj and bigobj.
                 */
                tx = dmu_tx_create(os);

                dmu_tx_hold_write(tx, dd.dd_packobj, packoff, packsize);
                dmu_tx_hold_write(tx, dd.dd_bigobj, bigoff, bigsize);

                if (ztest_random(100) == 0) {
                        error = -1;
                } else {
                        error = dmu_tx_assign(tx, TXG_WAIT);
                }

                if (error) {
                        if (error != -1) {
                                ztest_record_enospc("dmu r/w range");
                        }
                        dmu_tx_abort(tx);
                        umem_free(packbuf, packsize);
                        umem_free(bigbuf, bigsize);
                        for (j = 0; j < s; j++) {
                                if (i != 5) {
                                        dmu_return_arcbuf(bigbuf_arcbufs[j]);
                                } else {
                                        dmu_return_arcbuf(
                                            bigbuf_arcbufs[2 * j]);
                                        dmu_return_arcbuf(
                                            bigbuf_arcbufs[2 * j + 1]);
                                }
                        }
                        umem_free(bigbuf_arcbufs, 2 * s * sizeof (arc_buf_t *));
                        dmu_buf_rele(bonus_db, FTAG);
                        return;
                }

                txg = dmu_tx_get_txg(tx);

                /*
                 * 50% of the time don't read objects in the 1st iteration to
                 * test dmu_assign_arcbuf() for the case when there're no
                 * existing dbufs for the specified offsets.
                 */
                if (i != 0 || ztest_random(2) != 0) {
                        error = dmu_read(os, dd.dd_packobj, packoff,
                            packsize, packbuf, DMU_READ_PREFETCH);
                        ASSERT3U(error, ==, 0);
                        error = dmu_read(os, dd.dd_bigobj, bigoff, bigsize,
                            bigbuf, DMU_READ_PREFETCH);
                        ASSERT3U(error, ==, 0);
                }
                compare_and_update_pbbufs(s, packbuf, bigbuf, bigsize,
                    n, dd, txg);

                /*
                 * We've verified all the old bufwads, and made new ones.
                 * Now write them out.
                 */
                dmu_write(os, dd.dd_packobj, packoff, packsize, packbuf, tx);
                if (zopt_verbose >= 6) {
                        (void) printf("writing offset %llx size %llx"
                            " txg %llx\n",
                            (u_longlong_t)bigoff,
                            (u_longlong_t)bigsize,
                            (u_longlong_t)txg);
                }
                for (off = bigoff, j = 0; j < s; j++, off += dd.dd_chunk) {
                        dmu_buf_t *dbt;
                        if (i != 5) {
                                bcopy((caddr_t)bigbuf + (off - bigoff),
                                    bigbuf_arcbufs[j]->b_data, dd.dd_chunk);
                        } else {
                                bcopy((caddr_t)bigbuf + (off - bigoff),
                                    bigbuf_arcbufs[2 * j]->b_data,
                                    dd.dd_chunk / 2);
                                bcopy((caddr_t)bigbuf + (off - bigoff) +
                                    dd.dd_chunk / 2,
                                    bigbuf_arcbufs[2 * j + 1]->b_data,
                                    dd.dd_chunk / 2);
                        }

                        if (i == 1) {
                                VERIFY(dmu_buf_hold(os, dd.dd_bigobj, off,
                                    FTAG, &dbt) == 0);
                        }
                        if (i != 5) {
                                dmu_assign_arcbuf(bonus_db, off,
                                    bigbuf_arcbufs[j], tx);
                        } else {
                                dmu_assign_arcbuf(bonus_db, off,
                                    bigbuf_arcbufs[2 * j], tx);
                                dmu_assign_arcbuf(bonus_db,
                                    off + dd.dd_chunk / 2,
                                    bigbuf_arcbufs[2 * j + 1], tx);
                        }
                        if (i == 1) {
                                dmu_buf_rele(dbt, FTAG);
                        }
                }
                dmu_tx_commit(tx);

                /*
                 * Sanity check the stuff we just wrote.
                 */
                {
                        void *packcheck = umem_alloc(packsize, UMEM_NOFAIL);
                        void *bigcheck = umem_alloc(bigsize, UMEM_NOFAIL);

                        VERIFY(0 == dmu_read(os, dd.dd_packobj, packoff,
                            packsize, packcheck, DMU_READ_PREFETCH));
                        VERIFY(0 == dmu_read(os, dd.dd_bigobj, bigoff,
                            bigsize, bigcheck, DMU_READ_PREFETCH));

                        ASSERT(bcmp(packbuf, packcheck, packsize) == 0);
                        ASSERT(bcmp(bigbuf, bigcheck, bigsize) == 0);

                        umem_free(packcheck, packsize);
                        umem_free(bigcheck, bigsize);
                }
                if (i == 2) {
                        txg_wait_open(dmu_objset_pool(os), 0);
                } else if (i == 3) {
                        txg_wait_synced(dmu_objset_pool(os), 0);
                }
        }

        dmu_buf_rele(bonus_db, FTAG);
        umem_free(packbuf, packsize);
        umem_free(bigbuf, bigsize);
        umem_free(bigbuf_arcbufs, 2 * s * sizeof (arc_buf_t *));
}

void
ztest_dmu_check_future_leak(ztest_args_t *za)
{
        objset_t *os = za->za_os;
        dmu_buf_t *db;
        ztest_block_tag_t *bt;
        dmu_object_info_t *doi = &za->za_doi;

        /*
         * Make sure that, if there is a write record in the bonus buffer
         * of the ZTEST_DIROBJ, that the txg for this record is <= the
         * last synced txg of the pool.
         */
        VERIFY(dmu_bonus_hold(os, ZTEST_DIROBJ, FTAG, &db) == 0);
        za->za_dbuf = db;
        VERIFY(dmu_object_info(os, ZTEST_DIROBJ, doi) == 0);
        ASSERT3U(doi->doi_bonus_size, >=, sizeof (*bt));
        ASSERT3U(doi->doi_bonus_size, <=, db->db_size);
        ASSERT3U(doi->doi_bonus_size % sizeof (*bt), ==, 0);
        bt = (void *)((char *)db->db_data + doi->doi_bonus_size - sizeof (*bt));
        if (bt->bt_objset != 0) {
                ASSERT3U(bt->bt_objset, ==, dmu_objset_id(os));
                ASSERT3U(bt->bt_object, ==, ZTEST_DIROBJ);
                ASSERT3U(bt->bt_offset, ==, -1ULL);
                ASSERT3U(bt->bt_txg, <, spa_first_txg(za->za_spa));
        }
        dmu_buf_rele(db, FTAG);
        za->za_dbuf = NULL;
}

void
ztest_dmu_write_parallel(ztest_args_t *za)
{
        objset_t *os = za->za_os;
        ztest_block_tag_t *rbt = &za->za_rbt;
        ztest_block_tag_t *wbt = &za->za_wbt;
        const size_t btsize = sizeof (ztest_block_tag_t);
        dmu_buf_t *db;
        int b, error;
        int bs = ZTEST_DIROBJ_BLOCKSIZE;
        int do_free = 0;
        uint64_t off, txg, txg_how;
        mutex_t *lp;
        char osname[MAXNAMELEN];
        char iobuf[SPA_MAXBLOCKSIZE];
        blkptr_t blk = { 0 };
        uint64_t blkoff;
        zbookmark_t zb;
        dmu_tx_t *tx = dmu_tx_create(os);
        dmu_buf_t *bonus_db;
        arc_buf_t *abuf = NULL;

        dmu_objset_name(os, osname);

        /*
         * Have multiple threads write to large offsets in ZTEST_DIROBJ
         * to verify that having multiple threads writing to the same object
         * in parallel doesn't cause any trouble.
         */
        if (ztest_random(4) == 0) {
                /*
                 * Do the bonus buffer instead of a regular block.
                 * We need a lock to serialize resize vs. others,
                 * so we hash on the objset ID.
                 */
                b = dmu_objset_id(os) % ZTEST_SYNC_LOCKS;
                off = -1ULL;
                dmu_tx_hold_bonus(tx, ZTEST_DIROBJ);
        } else {
                b = ztest_random(ZTEST_SYNC_LOCKS);
                off = za->za_diroff_shared + (b << SPA_MAXBLOCKSHIFT);
                if (ztest_random(4) == 0) {
                        do_free = 1;
                        dmu_tx_hold_free(tx, ZTEST_DIROBJ, off, bs);
                } else {
                        dmu_tx_hold_write(tx, ZTEST_DIROBJ, off, bs);
                }
        }

        if (off != -1ULL && P2PHASE(off, bs) == 0 && !do_free &&
            ztest_random(8) == 0) {
                VERIFY(dmu_bonus_hold(os, ZTEST_DIROBJ, FTAG, &bonus_db) == 0);
                abuf = dmu_request_arcbuf(bonus_db, bs);
        }

        txg_how = ztest_random(2) == 0 ? TXG_WAIT : TXG_NOWAIT;
        error = dmu_tx_assign(tx, txg_how);
        if (error) {
                if (error == ERESTART) {
                        ASSERT(txg_how == TXG_NOWAIT);
                        dmu_tx_wait(tx);
                } else {
                        ztest_record_enospc("dmu write parallel");
                }
                dmu_tx_abort(tx);
                if (abuf != NULL) {
                        dmu_return_arcbuf(abuf);
                        dmu_buf_rele(bonus_db, FTAG);
                }
                return;
        }
        txg = dmu_tx_get_txg(tx);

        lp = &ztest_shared->zs_sync_lock[b];
        (void) mutex_lock(lp);

        wbt->bt_objset = dmu_objset_id(os);
        wbt->bt_object = ZTEST_DIROBJ;
        wbt->bt_offset = off;
        wbt->bt_txg = txg;
        wbt->bt_thread = za->za_instance;
        wbt->bt_seq = ztest_shared->zs_seq[b]++;        /* protected by lp */

        /*
         * Occasionally, write an all-zero block to test the behavior
         * of blocks that compress into holes.
         */
        if (off != -1ULL && ztest_random(8) == 0)
                bzero(wbt, btsize);

        if (off == -1ULL) {
                dmu_object_info_t *doi = &za->za_doi;
                char *dboff;

                VERIFY(dmu_bonus_hold(os, ZTEST_DIROBJ, FTAG, &db) == 0);
                za->za_dbuf = db;
                dmu_object_info_from_db(db, doi);
                ASSERT3U(doi->doi_bonus_size, <=, db->db_size);
                ASSERT3U(doi->doi_bonus_size, >=, btsize);
                ASSERT3U(doi->doi_bonus_size % btsize, ==, 0);
                dboff = (char *)db->db_data + doi->doi_bonus_size - btsize;
                bcopy(dboff, rbt, btsize);
                if (rbt->bt_objset != 0) {
                        ASSERT3U(rbt->bt_objset, ==, wbt->bt_objset);
                        ASSERT3U(rbt->bt_object, ==, wbt->bt_object);
                        ASSERT3U(rbt->bt_offset, ==, wbt->bt_offset);
                        ASSERT3U(rbt->bt_txg, <=, wbt->bt_txg);
                }
                if (ztest_random(10) == 0) {
                        int newsize = (ztest_random(db->db_size /
                            btsize) + 1) * btsize;

                        ASSERT3U(newsize, >=, btsize);
                        ASSERT3U(newsize, <=, db->db_size);
                        VERIFY3U(dmu_set_bonus(db, newsize, tx), ==, 0);
                        dboff = (char *)db->db_data + newsize - btsize;
                }
                dmu_buf_will_dirty(db, tx);
                bcopy(wbt, dboff, btsize);
                dmu_buf_rele(db, FTAG);
                za->za_dbuf = NULL;
        } else if (do_free) {
                VERIFY(dmu_free_range(os, ZTEST_DIROBJ, off, bs, tx) == 0);
        } else if (abuf == NULL) {
                dmu_write(os, ZTEST_DIROBJ, off, btsize, wbt, tx);
        } else {
                bcopy(wbt, abuf->b_data, btsize);
                dmu_assign_arcbuf(bonus_db, off, abuf, tx);
                dmu_buf_rele(bonus_db, FTAG);
        }

        (void) mutex_unlock(lp);

        if (ztest_random(1000) == 0)
                (void) poll(NULL, 0, 1); /* open dn_notxholds window */

        dmu_tx_commit(tx);

        if (ztest_random(10000) == 0)
                txg_wait_synced(dmu_objset_pool(os), txg);

        if (off == -1ULL || do_free)
                return;

        if (ztest_random(2) != 0)
                return;

        /*
         * dmu_sync() the block we just wrote.
         */
        (void) mutex_lock(lp);

        blkoff = P2ALIGN_TYPED(off, bs, uint64_t);
        error = dmu_buf_hold(os, ZTEST_DIROBJ, blkoff, FTAG, &db);
        za->za_dbuf = db;
        if (error) {
                (void) mutex_unlock(lp);
                return;
        }
        blkoff = off - blkoff;
        error = dmu_sync(NULL, db, &blk, txg, NULL, NULL);
        dmu_buf_rele(db, FTAG);
        za->za_dbuf = NULL;

        if (error) {
                (void) mutex_unlock(lp);
                return;
        }

        if (blk.blk_birth == 0) {       /* concurrent free */
                (void) mutex_unlock(lp);
                return;
        }

        txg_suspend(dmu_objset_pool(os));

        (void) mutex_unlock(lp);

        ASSERT(blk.blk_fill == 1);
        ASSERT3U(BP_GET_TYPE(&blk), ==, DMU_OT_UINT64_OTHER);
        ASSERT3U(BP_GET_LEVEL(&blk), ==, 0);
        ASSERT3U(BP_GET_LSIZE(&blk), ==, bs);

        /*
         * Read the block that dmu_sync() returned to make sure its contents
         * match what we wrote.  We do this while still txg_suspend()ed
         * to ensure that the block can't be reused before we read it.
         */
        zb.zb_objset = dmu_objset_id(os);
        zb.zb_object = ZTEST_DIROBJ;
        zb.zb_level = 0;
        zb.zb_blkid = off / bs;
        error = zio_wait(zio_read(NULL, za->za_spa, &blk, iobuf, bs,
            NULL, NULL, ZIO_PRIORITY_SYNC_READ, ZIO_FLAG_MUSTSUCCEED, &zb));
        ASSERT3U(error, ==, 0);

        txg_resume(dmu_objset_pool(os));

        bcopy(&iobuf[blkoff], rbt, btsize);

        if (rbt->bt_objset == 0)                /* concurrent free */
                return;

        if (wbt->bt_objset == 0)                /* all-zero overwrite */
                return;

        ASSERT3U(rbt->bt_objset, ==, wbt->bt_objset);
        ASSERT3U(rbt->bt_object, ==, wbt->bt_object);
        ASSERT3U(rbt->bt_offset, ==, wbt->bt_offset);

        /*
         * The semantic of dmu_sync() is that we always push the most recent
         * version of the data, so in the face of concurrent updates we may
         * see a newer version of the block.  That's OK.
         */
        ASSERT3U(rbt->bt_txg, >=, wbt->bt_txg);
        if (rbt->bt_thread == wbt->bt_thread)
                ASSERT3U(rbt->bt_seq, ==, wbt->bt_seq);
        else
                ASSERT3U(rbt->bt_seq, >, wbt->bt_seq);
}

/*
 * Verify that zap_{create,destroy,add,remove,update} work as expected.
 */
#define ZTEST_ZAP_MIN_INTS      1
#define ZTEST_ZAP_MAX_INTS      4
#define ZTEST_ZAP_MAX_PROPS     1000

void
ztest_zap(ztest_args_t *za)
{
        objset_t *os = za->za_os;
        uint64_t object;
        uint64_t txg, last_txg;
        uint64_t value[ZTEST_ZAP_MAX_INTS];
        uint64_t zl_ints, zl_intsize, prop;
        int i, ints;
        dmu_tx_t *tx;
        char propname[100], txgname[100];
        int error;
        char osname[MAXNAMELEN];
        char *hc[2] = { "s.acl.h", ".s.open.h.hyLZlg" };

        dmu_objset_name(os, osname);

        /*
         * Create a new object if necessary, and record it in the directory.
         */
        VERIFY(0 == dmu_read(os, ZTEST_DIROBJ, za->za_diroff,
            sizeof (uint64_t), &object, DMU_READ_PREFETCH));

        if (object == 0) {
                tx = dmu_tx_create(os);
                dmu_tx_hold_write(tx, ZTEST_DIROBJ, za->za_diroff,
                    sizeof (uint64_t));
                dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, TRUE, NULL);
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        ztest_record_enospc("create zap test obj");
                        dmu_tx_abort(tx);
                        return;
                }
                object = zap_create(os, DMU_OT_ZAP_OTHER, DMU_OT_NONE, 0, tx);
                if (error) {
                        fatal(0, "zap_create('%s', %llu) = %d",
                            osname, object, error);
                }
                ASSERT(object != 0);
                dmu_write(os, ZTEST_DIROBJ, za->za_diroff,
                    sizeof (uint64_t), &object, tx);
                /*
                 * Generate a known hash collision, and verify that
                 * we can lookup and remove both entries.
                 */
                for (i = 0; i < 2; i++) {
                        value[i] = i;
                        error = zap_add(os, object, hc[i], sizeof (uint64_t),
                            1, &value[i], tx);
                        ASSERT3U(error, ==, 0);
                }
                for (i = 0; i < 2; i++) {
                        error = zap_add(os, object, hc[i], sizeof (uint64_t),
                            1, &value[i], tx);
                        ASSERT3U(error, ==, EEXIST);
                        error = zap_length(os, object, hc[i],
                            &zl_intsize, &zl_ints);
                        ASSERT3U(error, ==, 0);
                        ASSERT3U(zl_intsize, ==, sizeof (uint64_t));
                        ASSERT3U(zl_ints, ==, 1);
                }
                for (i = 0; i < 2; i++) {
                        error = zap_remove(os, object, hc[i], tx);
                        ASSERT3U(error, ==, 0);
                }

                dmu_tx_commit(tx);
        }

        ints = MAX(ZTEST_ZAP_MIN_INTS, object % ZTEST_ZAP_MAX_INTS);

        prop = ztest_random(ZTEST_ZAP_MAX_PROPS);
        (void) sprintf(propname, "prop_%llu", (u_longlong_t)prop);
        (void) sprintf(txgname, "txg_%llu", (u_longlong_t)prop);
        bzero(value, sizeof (value));
        last_txg = 0;

        /*
         * If these zap entries already exist, validate their contents.
         */
        error = zap_length(os, object, txgname, &zl_intsize, &zl_ints);
        if (error == 0) {
                ASSERT3U(zl_intsize, ==, sizeof (uint64_t));
                ASSERT3U(zl_ints, ==, 1);

                VERIFY(zap_lookup(os, object, txgname, zl_intsize,
                    zl_ints, &last_txg) == 0);

                VERIFY(zap_length(os, object, propname, &zl_intsize,
                    &zl_ints) == 0);

                ASSERT3U(zl_intsize, ==, sizeof (uint64_t));
                ASSERT3U(zl_ints, ==, ints);

                VERIFY(zap_lookup(os, object, propname, zl_intsize,
                    zl_ints, value) == 0);

                for (i = 0; i < ints; i++) {
                        ASSERT3U(value[i], ==, last_txg + object + i);
                }
        } else {
                ASSERT3U(error, ==, ENOENT);
        }

        /*
         * Atomically update two entries in our zap object.
         * The first is named txg_%llu, and contains the txg
         * in which the property was last updated.  The second
         * is named prop_%llu, and the nth element of its value
         * should be txg + object + n.
         */
        tx = dmu_tx_create(os);
        dmu_tx_hold_zap(tx, object, TRUE, NULL);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                ztest_record_enospc("create zap entry");
                dmu_tx_abort(tx);
                return;
        }
        txg = dmu_tx_get_txg(tx);

        if (last_txg > txg)
                fatal(0, "zap future leak: old %llu new %llu", last_txg, txg);

        for (i = 0; i < ints; i++)
                value[i] = txg + object + i;

        error = zap_update(os, object, txgname, sizeof (uint64_t), 1, &txg, tx);
        if (error)
                fatal(0, "zap_update('%s', %llu, '%s') = %d",
                    osname, object, txgname, error);

        error = zap_update(os, object, propname, sizeof (uint64_t),
            ints, value, tx);
        if (error)
                fatal(0, "zap_update('%s', %llu, '%s') = %d",
                    osname, object, propname, error);

        dmu_tx_commit(tx);

        /*
         * Remove a random pair of entries.
         */
        prop = ztest_random(ZTEST_ZAP_MAX_PROPS);
        (void) sprintf(propname, "prop_%llu", (u_longlong_t)prop);
        (void) sprintf(txgname, "txg_%llu", (u_longlong_t)prop);

        error = zap_length(os, object, txgname, &zl_intsize, &zl_ints);

        if (error == ENOENT)
                return;

        ASSERT3U(error, ==, 0);

        tx = dmu_tx_create(os);
        dmu_tx_hold_zap(tx, object, TRUE, NULL);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                ztest_record_enospc("remove zap entry");
                dmu_tx_abort(tx);
                return;
        }
        error = zap_remove(os, object, txgname, tx);
        if (error)
                fatal(0, "zap_remove('%s', %llu, '%s') = %d",
                    osname, object, txgname, error);

        error = zap_remove(os, object, propname, tx);
        if (error)
                fatal(0, "zap_remove('%s', %llu, '%s') = %d",
                    osname, object, propname, error);

        dmu_tx_commit(tx);

        /*
         * Once in a while, destroy the object.
         */
        if (ztest_random(1000) != 0)
                return;

        tx = dmu_tx_create(os);
        dmu_tx_hold_write(tx, ZTEST_DIROBJ, za->za_diroff, sizeof (uint64_t));
        dmu_tx_hold_free(tx, object, 0, DMU_OBJECT_END);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                ztest_record_enospc("destroy zap object");
                dmu_tx_abort(tx);
                return;
        }
        error = zap_destroy(os, object, tx);
        if (error)
                fatal(0, "zap_destroy('%s', %llu) = %d",
                    osname, object, error);
        object = 0;
        dmu_write(os, ZTEST_DIROBJ, za->za_diroff, sizeof (uint64_t),
            &object, tx);
        dmu_tx_commit(tx);
}

void
ztest_zap_parallel(ztest_args_t *za)
{
        objset_t *os = za->za_os;
        uint64_t txg, object, count, wsize, wc, zl_wsize, zl_wc;
        dmu_tx_t *tx;
        int i, namelen, error;
        char name[20], string_value[20];
        void *data;

        /*
         * Generate a random name of the form 'xxx.....' where each
         * x is a random printable character and the dots are dots.
         * There are 94 such characters, and the name length goes from
         * 6 to 20, so there are 94^3 * 15 = 12,458,760 possible names.
         */
        namelen = ztest_random(sizeof (name) - 5) + 5 + 1;

        for (i = 0; i < 3; i++)
                name[i] = '!' + ztest_random('~' - '!' + 1);
        for (; i < namelen - 1; i++)
                name[i] = '.';
        name[i] = '\0';

        if (ztest_random(2) == 0)
                object = ZTEST_MICROZAP_OBJ;
        else
                object = ZTEST_FATZAP_OBJ;

        if ((namelen & 1) || object == ZTEST_MICROZAP_OBJ) {
                wsize = sizeof (txg);
                wc = 1;
                data = &txg;
        } else {
                wsize = 1;
                wc = namelen;
                data = string_value;
        }

        count = -1ULL;
        VERIFY(zap_count(os, object, &count) == 0);
        ASSERT(count != -1ULL);

        /*
         * Select an operation: length, lookup, add, update, remove.
         */
        i = ztest_random(5);

        if (i >= 2) {
                tx = dmu_tx_create(os);
                dmu_tx_hold_zap(tx, object, TRUE, NULL);
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        ztest_record_enospc("zap parallel");
                        dmu_tx_abort(tx);
                        return;
                }
                txg = dmu_tx_get_txg(tx);
                bcopy(name, string_value, namelen);
        } else {
                tx = NULL;
                txg = 0;
                bzero(string_value, namelen);
        }

        switch (i) {

        case 0:
                error = zap_length(os, object, name, &zl_wsize, &zl_wc);
                if (error == 0) {
                        ASSERT3U(wsize, ==, zl_wsize);
                        ASSERT3U(wc, ==, zl_wc);
                } else {
                        ASSERT3U(error, ==, ENOENT);
                }
                break;

        case 1:
                error = zap_lookup(os, object, name, wsize, wc, data);
                if (error == 0) {
                        if (data == string_value &&
                            bcmp(name, data, namelen) != 0)
                                fatal(0, "name '%s' != val '%s' len %d",
                                    name, data, namelen);
                } else {
                        ASSERT3U(error, ==, ENOENT);
                }
                break;

        case 2:
                error = zap_add(os, object, name, wsize, wc, data, tx);
                ASSERT(error == 0 || error == EEXIST);
                break;

        case 3:
                VERIFY(zap_update(os, object, name, wsize, wc, data, tx) == 0);
                break;

        case 4:
                error = zap_remove(os, object, name, tx);
                ASSERT(error == 0 || error == ENOENT);
                break;
        }

        if (tx != NULL)
                dmu_tx_commit(tx);
}

void
ztest_dsl_prop_get_set(ztest_args_t *za)
{
        objset_t *os = za->za_os;
        int i, inherit;
        uint64_t value;
        const char *prop, *valname;
        char setpoint[MAXPATHLEN];
        char osname[MAXNAMELEN];
        int error;

        (void) rw_rdlock(&ztest_shared->zs_name_lock);

        dmu_objset_name(os, osname);

        for (i = 0; i < 2; i++) {
                if (i == 0) {
                        prop = "checksum";
                        value = ztest_random_checksum();
                        inherit = (value == ZIO_CHECKSUM_INHERIT);
                } else {
                        prop = "compression";
                        value = ztest_random_compress();
                        inherit = (value == ZIO_COMPRESS_INHERIT);
                }

                error = dsl_prop_set(osname, prop, sizeof (value),
                    !inherit, &value);

                if (error == ENOSPC) {
                        ztest_record_enospc("dsl_prop_set");
                        break;
                }

                ASSERT3U(error, ==, 0);

                VERIFY3U(dsl_prop_get(osname, prop, sizeof (value),
                    1, &value, setpoint), ==, 0);

                if (i == 0)
                        valname = zio_checksum_table[value].ci_name;
                else
                        valname = zio_compress_table[value].ci_name;

                if (zopt_verbose >= 6) {
                        (void) printf("%s %s = %s for '%s'\n",
                            osname, prop, valname, setpoint);
                }
        }

        (void) rw_unlock(&ztest_shared->zs_name_lock);
}

/*
 * Inject random faults into the on-disk data.
 */
void
ztest_fault_inject(ztest_args_t *za)
{
        int fd;
        uint64_t offset;
        uint64_t leaves = MAX(zopt_mirrors, 1) * zopt_raidz;
        uint64_t bad = 0x1990c0ffeedecade;
        uint64_t top, leaf;
        char path0[MAXPATHLEN];
        char pathrand[MAXPATHLEN];
        size_t fsize;
        spa_t *spa = za->za_spa;
        int bshift = SPA_MAXBLOCKSHIFT + 2;     /* don't scrog all labels */
        int iters = 1000;
        int maxfaults = zopt_maxfaults;
        vdev_t *vd0 = NULL;
        uint64_t guid0 = 0;

        ASSERT(leaves >= 1);

        /*
         * We need SCL_STATE here because we're going to look at vd0->vdev_tsd.
         */
        spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);

        if (ztest_random(2) == 0) {
                /*
                 * Inject errors on a normal data device.
                 */
                top = ztest_random(spa->spa_root_vdev->vdev_children);
                leaf = ztest_random(leaves);

                /*
                 * Generate paths to the first leaf in this top-level vdev,
                 * and to the random leaf we selected.  We'll induce transient
                 * write failures and random online/offline activity on leaf 0,
                 * and we'll write random garbage to the randomly chosen leaf.
                 */
                (void) snprintf(path0, sizeof (path0), ztest_dev_template,
                    zopt_dir, zopt_pool, top * leaves + 0);
                (void) snprintf(pathrand, sizeof (pathrand), ztest_dev_template,
                    zopt_dir, zopt_pool, top * leaves + leaf);

                vd0 = vdev_lookup_by_path(spa->spa_root_vdev, path0);
                if (vd0 != NULL && maxfaults != 1) {
                        /*
                         * Make vd0 explicitly claim to be unreadable,
                         * or unwriteable, or reach behind its back
                         * and close the underlying fd.  We can do this if
                         * maxfaults == 0 because we'll fail and reexecute,
                         * and we can do it if maxfaults >= 2 because we'll
                         * have enough redundancy.  If maxfaults == 1, the
                         * combination of this with injection of random data
                         * corruption below exceeds the pool's fault tolerance.
                         */
                        vdev_file_t *vf = vd0->vdev_tsd;

                        if (vf != NULL && ztest_random(3) == 0) {
                                (void) close(vf->vf_vnode->v_fd);
                                vf->vf_vnode->v_fd = -1;
                        } else if (ztest_random(2) == 0) {
                                vd0->vdev_cant_read = B_TRUE;
                        } else {
                                vd0->vdev_cant_write = B_TRUE;
                        }
                        guid0 = vd0->vdev_guid;
                }
        } else {
                /*
                 * Inject errors on an l2cache device.
                 */
                spa_aux_vdev_t *sav = &spa->spa_l2cache;

                if (sav->sav_count == 0) {
                        spa_config_exit(spa, SCL_STATE, FTAG);
                        return;
                }
                vd0 = sav->sav_vdevs[ztest_random(sav->sav_count)];
                guid0 = vd0->vdev_guid;
                (void) strcpy(path0, vd0->vdev_path);
                (void) strcpy(pathrand, vd0->vdev_path);

                leaf = 0;
                leaves = 1;
                maxfaults = INT_MAX;    /* no limit on cache devices */
        }

        spa_config_exit(spa, SCL_STATE, FTAG);

        if (maxfaults == 0)
                return;

        /*
         * If we can tolerate two or more faults, randomly online/offline vd0.
         */
        if (maxfaults >= 2 && guid0 != 0) {
                if (ztest_random(10) < 6) {
                        int flags = (ztest_random(2) == 0 ?
                            ZFS_OFFLINE_TEMPORARY : 0);
                        VERIFY(vdev_offline(spa, guid0, flags) != EBUSY);
                } else {
                        (void) vdev_online(spa, guid0, 0, NULL);
                }
        }

        /*
         * We have at least single-fault tolerance, so inject data corruption.
         */
        fd = open(pathrand, O_RDWR);

        if (fd == -1)   /* we hit a gap in the device namespace */
                return;

        fsize = lseek(fd, 0, SEEK_END);

        while (--iters != 0) {
                offset = ztest_random(fsize / (leaves << bshift)) *
                    (leaves << bshift) + (leaf << bshift) +
                    (ztest_random(1ULL << (bshift - 1)) & -8ULL);

                if (offset >= fsize)
                        continue;

                if (zopt_verbose >= 6)
                        (void) printf("injecting bad word into %s,"
                            " offset 0x%llx\n", pathrand, (u_longlong_t)offset);

                if (pwrite(fd, &bad, sizeof (bad), offset) != sizeof (bad))
                        fatal(1, "can't inject bad word at 0x%llx in %s",
                            offset, pathrand);
        }

        (void) close(fd);
}

/*
 * Scrub the pool.
 */
void
ztest_scrub(ztest_args_t *za)
{
        spa_t *spa = za->za_spa;

        (void) spa_scrub(spa, POOL_SCRUB_EVERYTHING);
        (void) poll(NULL, 0, 1000); /* wait a second, then force a restart */
        (void) spa_scrub(spa, POOL_SCRUB_EVERYTHING);
}

/*
 * Rename the pool to a different name and then rename it back.
 */
void
ztest_spa_rename(ztest_args_t *za)
{
        char *oldname, *newname;
        int error;
        spa_t *spa;

        (void) rw_wrlock(&ztest_shared->zs_name_lock);

        oldname = za->za_pool;
        newname = umem_alloc(strlen(oldname) + 5, UMEM_NOFAIL);
        (void) strcpy(newname, oldname);
        (void) strcat(newname, "_tmp");

        /*
         * Do the rename
         */
        error = spa_rename(oldname, newname);
        if (error)
                fatal(0, "spa_rename('%s', '%s') = %d", oldname,
                    newname, error);

        /*
         * Try to open it under the old name, which shouldn't exist
         */
        error = spa_open(oldname, &spa, FTAG);
        if (error != ENOENT)
                fatal(0, "spa_open('%s') = %d", oldname, error);

        /*
         * Open it under the new name and make sure it's still the same spa_t.
         */
        error = spa_open(newname, &spa, FTAG);
        if (error != 0)
                fatal(0, "spa_open('%s') = %d", newname, error);

        ASSERT(spa == za->za_spa);
        spa_close(spa, FTAG);

        /*
         * Rename it back to the original
         */
        error = spa_rename(newname, oldname);
        if (error)
                fatal(0, "spa_rename('%s', '%s') = %d", newname,
                    oldname, error);

        /*
         * Make sure it can still be opened
         */
        error = spa_open(oldname, &spa, FTAG);
        if (error != 0)
                fatal(0, "spa_open('%s') = %d", oldname, error);

        ASSERT(spa == za->za_spa);
        spa_close(spa, FTAG);

        umem_free(newname, strlen(newname) + 1);

        (void) rw_unlock(&ztest_shared->zs_name_lock);
}


/*
 * Completely obliterate one disk.
 */
static void
ztest_obliterate_one_disk(uint64_t vdev)
{
        int fd;
        char dev_name[MAXPATHLEN], copy_name[MAXPATHLEN];
        size_t fsize;

        if (zopt_maxfaults < 2)
                return;

        (void) sprintf(dev_name, ztest_dev_template, zopt_dir, zopt_pool, vdev);
        (void) snprintf(copy_name, MAXPATHLEN, "%s.old", dev_name);

        fd = open(dev_name, O_RDWR);

        if (fd == -1)
                fatal(1, "can't open %s", dev_name);

        /*
         * Determine the size.
         */
        fsize = lseek(fd, 0, SEEK_END);

        (void) close(fd);

        /*
         * Rename the old device to dev_name.old (useful for debugging).
         */
        VERIFY(rename(dev_name, copy_name) == 0);

        /*
         * Create a new one.
         */
        VERIFY((fd = open(dev_name, O_RDWR | O_CREAT | O_TRUNC, 0666)) >= 0);
        VERIFY(ftruncate(fd, fsize) == 0);
        (void) close(fd);
}

static void
ztest_replace_one_disk(spa_t *spa, uint64_t vdev)
{
        char dev_name[MAXPATHLEN];
        nvlist_t *root;
        int error;
        uint64_t guid;
        vdev_t *vd;

        (void) sprintf(dev_name, ztest_dev_template, zopt_dir, zopt_pool, vdev);

        /*
         * Build the nvlist describing dev_name.
         */
        root = make_vdev_root(dev_name, NULL, 0, 0, 0, 0, 0, 1);

        spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);
        if ((vd = vdev_lookup_by_path(spa->spa_root_vdev, dev_name)) == NULL)
                guid = 0;
        else
                guid = vd->vdev_guid;
        spa_config_exit(spa, SCL_VDEV, FTAG);
        error = spa_vdev_attach(spa, guid, root, B_TRUE);
        if (error != 0 &&
            error != EBUSY &&
            error != ENOTSUP &&
            error != ENODEV &&
            error != EDOM)
                fatal(0, "spa_vdev_attach(in-place) = %d", error);

        nvlist_free(root);
}

static void
ztest_verify_blocks(char *pool)
{
        int status;
        char zdb[MAXPATHLEN + MAXNAMELEN + 20];
        char zbuf[1024];
        char *bin;
        char *ztest;
        char *isa;
        int isalen;
        FILE *fp;

        (void) realpath(getexecname(), zdb);

        /* zdb lives in /usr/sbin, while ztest lives in /usr/bin */
        bin = strstr(zdb, "/usr/bin/");
        ztest = strstr(bin, "/ztest");
        isa = bin + 8;
        isalen = ztest - isa;
        isa = strdup(isa);
        /* LINTED */
        (void) sprintf(bin,
            "/usr/sbin%.*s/zdb -bcc%s%s -U /tmp/zpool.cache %s",
            isalen,
            isa,
            zopt_verbose >= 3 ? "s" : "",
            zopt_verbose >= 4 ? "v" : "",
            pool);
        free(isa);

        if (zopt_verbose >= 5)
                (void) printf("Executing %s\n", strstr(zdb, "zdb "));

        fp = popen(zdb, "r");

        while (fgets(zbuf, sizeof (zbuf), fp) != NULL)
                if (zopt_verbose >= 3)
                        (void) printf("%s", zbuf);

        status = pclose(fp);

        if (status == 0)
                return;

        ztest_dump_core = 0;
        if (WIFEXITED(status))
                fatal(0, "'%s' exit code %d", zdb, WEXITSTATUS(status));
        else
                fatal(0, "'%s' died with signal %d", zdb, WTERMSIG(status));
}

static void
ztest_walk_pool_directory(char *header)
{
        spa_t *spa = NULL;

        if (zopt_verbose >= 6)
                (void) printf("%s\n", header);

        mutex_enter(&spa_namespace_lock);
        while ((spa = spa_next(spa)) != NULL)
                if (zopt_verbose >= 6)
                        (void) printf("\t%s\n", spa_name(spa));
        mutex_exit(&spa_namespace_lock);
}

static void
ztest_spa_import_export(char *oldname, char *newname)
{
        nvlist_t *config, *newconfig;
        uint64_t pool_guid;
        spa_t *spa;
        int error;

        if (zopt_verbose >= 4) {
                (void) printf("import/export: old = %s, new = %s\n",
                    oldname, newname);
        }

        /*
         * Clean up from previous runs.
         */
        (void) spa_destroy(newname);

        /*
         * Get the pool's configuration and guid.
         */
        error = spa_open(oldname, &spa, FTAG);
        if (error)
                fatal(0, "spa_open('%s') = %d", oldname, error);

        /*
         * Kick off a scrub to tickle scrub/export races.
         */
        if (ztest_random(2) == 0)
                (void) spa_scrub(spa, POOL_SCRUB_EVERYTHING);

        pool_guid = spa_guid(spa);
        spa_close(spa, FTAG);

        ztest_walk_pool_directory("pools before export");

        /*
         * Export it.
         */
        error = spa_export(oldname, &config, B_FALSE, B_FALSE);
        if (error)
                fatal(0, "spa_export('%s') = %d", oldname, error);

        ztest_walk_pool_directory("pools after export");

        /*
         * Try to import it.
         */
        newconfig = spa_tryimport(config);
        ASSERT(newconfig != NULL);
        nvlist_free(newconfig);

        /*
         * Import it under the new name.
         */
        error = spa_import(newname, config, NULL);
        if (error)
                fatal(0, "spa_import('%s') = %d", newname, error);

        ztest_walk_pool_directory("pools after import");

        /*
         * Try to import it again -- should fail with EEXIST.
         */
        error = spa_import(newname, config, NULL);
        if (error != EEXIST)
                fatal(0, "spa_import('%s') twice", newname);

        /*
         * Try to import it under a different name -- should fail with EEXIST.
         */
        error = spa_import(oldname, config, NULL);
        if (error != EEXIST)
                fatal(0, "spa_import('%s') under multiple names", newname);

        /*
         * Verify that the pool is no longer visible under the old name.
         */
        error = spa_open(oldname, &spa, FTAG);
        if (error != ENOENT)
                fatal(0, "spa_open('%s') = %d", newname, error);

        /*
         * Verify that we can open and close the pool using the new name.
         */
        error = spa_open(newname, &spa, FTAG);
        if (error)
                fatal(0, "spa_open('%s') = %d", newname, error);
        ASSERT(pool_guid == spa_guid(spa));
        spa_close(spa, FTAG);

        nvlist_free(config);
}

static void
ztest_resume(spa_t *spa)
{
        if (spa_suspended(spa)) {
                spa_vdev_state_enter(spa);
                vdev_clear(spa, NULL);
                (void) spa_vdev_state_exit(spa, NULL, 0);
                (void) zio_resume(spa);
        }
}

static void *
ztest_resume_thread(void *arg)
{
        spa_t *spa = arg;

        while (!ztest_exiting) {
                (void) poll(NULL, 0, 1000);
                ztest_resume(spa);
        }
        return (NULL);
}

static void *
ztest_thread(void *arg)
{
        ztest_args_t *za = arg;
        ztest_shared_t *zs = ztest_shared;
        hrtime_t now, functime;
        ztest_info_t *zi;
        int f, i;

        while ((now = gethrtime()) < za->za_stop) {
                /*
                 * See if it's time to force a crash.
                 */
                if (now > za->za_kill) {
                        zs->zs_alloc = spa_get_alloc(za->za_spa);
                        zs->zs_space = spa_get_space(za->za_spa);
                        (void) kill(getpid(), SIGKILL);
                }

                /*
                 * Pick a random function.
                 */
                f = ztest_random(ZTEST_FUNCS);
                zi = &zs->zs_info[f];

                /*
                 * Decide whether to call it, based on the requested frequency.
                 */
                if (zi->zi_call_target == 0 ||
                    (double)zi->zi_call_total / zi->zi_call_target >
                    (double)(now - zs->zs_start_time) / (zopt_time * NANOSEC))
                        continue;

                atomic_add_64(&zi->zi_calls, 1);
                atomic_add_64(&zi->zi_call_total, 1);

                za->za_diroff = (za->za_instance * ZTEST_FUNCS + f) *
                    ZTEST_DIRSIZE;
                za->za_diroff_shared = (1ULL << 63);

                for (i = 0; i < zi->zi_iters; i++)
                        zi->zi_func(za);

                functime = gethrtime() - now;

                atomic_add_64(&zi->zi_call_time, functime);

                if (zopt_verbose >= 4) {
                        Dl_info dli;
                        (void) dladdr((void *)zi->zi_func, &dli);
                        (void) printf("%6.2f sec in %s\n",
                            (double)functime / NANOSEC, dli.dli_sname);
                }

                /*
                 * If we're getting ENOSPC with some regularity, stop.
                 */
                if (zs->zs_enospc_count > 10)
                        break;
        }

        return (NULL);
}

/*
 * Kick off threads to run tests on all datasets in parallel.
 */
static void
ztest_run(char *pool)
{
        int t, d, error;
        ztest_shared_t *zs = ztest_shared;
        ztest_args_t *za;
        spa_t *spa;
        char name[100];
        thread_t resume_tid;

        ztest_exiting = B_FALSE;

        (void) _mutex_init(&zs->zs_vdev_lock, USYNC_THREAD, NULL);
        (void) rwlock_init(&zs->zs_name_lock, USYNC_THREAD, NULL);

        for (t = 0; t < ZTEST_SYNC_LOCKS; t++)
                (void) _mutex_init(&zs->zs_sync_lock[t], USYNC_THREAD, NULL);

        /*
         * Destroy one disk before we even start.
         * It's mirrored, so everything should work just fine.
         * This makes us exercise fault handling very early in spa_load().
         */
        ztest_obliterate_one_disk(0);

        /*
         * Verify that the sum of the sizes of all blocks in the pool
         * equals the SPA's allocated space total.
         */
        ztest_verify_blocks(pool);

        /*
         * Kick off a replacement of the disk we just obliterated.
         */
        kernel_init(FREAD | FWRITE);
        VERIFY(spa_open(pool, &spa, FTAG) == 0);
        ztest_replace_one_disk(spa, 0);
        if (zopt_verbose >= 5)
                show_pool_stats(spa);
        spa_close(spa, FTAG);
        kernel_fini();

        kernel_init(FREAD | FWRITE);

        /*
         * Verify that we can export the pool and reimport it under a
         * different name.
         */
        if (ztest_random(2) == 0) {
                (void) snprintf(name, 100, "%s_import", pool);
                ztest_spa_import_export(pool, name);
                ztest_spa_import_export(name, pool);
        }

        /*
         * Verify that we can loop over all pools.
         */
        mutex_enter(&spa_namespace_lock);
        for (spa = spa_next(NULL); spa != NULL; spa = spa_next(spa)) {
                if (zopt_verbose > 3) {
                        (void) printf("spa_next: found %s\n", spa_name(spa));
                }
        }
        mutex_exit(&spa_namespace_lock);

        /*
         * Open our pool.
         */
        VERIFY(spa_open(pool, &spa, FTAG) == 0);

        /*
         * We don't expect the pool to suspend unless maxfaults == 0,
         * in which case ztest_fault_inject() temporarily takes away
         * the only valid replica.
         */
        if (zopt_maxfaults == 0)
                spa->spa_failmode = ZIO_FAILURE_MODE_WAIT;
        else
                spa->spa_failmode = ZIO_FAILURE_MODE_PANIC;

        /*
         * Create a thread to periodically resume suspended I/O.
         */
        VERIFY(thr_create(0, 0, ztest_resume_thread, spa, THR_BOUND,
            &resume_tid) == 0);

        /*
         * Verify that we can safely inquire about about any object,
         * whether it's allocated or not.  To make it interesting,
         * we probe a 5-wide window around each power of two.
         * This hits all edge cases, including zero and the max.
         */
        for (t = 0; t < 64; t++) {
                for (d = -5; d <= 5; d++) {
                        error = dmu_object_info(spa->spa_meta_objset,
                            (1ULL << t) + d, NULL);
                        ASSERT(error == 0 || error == ENOENT ||
                            error == EINVAL);
                }
        }

        /*
         * Now kick off all the tests that run in parallel.
         */
        zs->zs_enospc_count = 0;

        za = umem_zalloc(zopt_threads * sizeof (ztest_args_t), UMEM_NOFAIL);

        if (zopt_verbose >= 4)
                (void) printf("starting main threads...\n");

        za[0].za_start = gethrtime();
        za[0].za_stop = za[0].za_start + zopt_passtime * NANOSEC;
        za[0].za_stop = MIN(za[0].za_stop, zs->zs_stop_time);
        za[0].za_kill = za[0].za_stop;
        if (ztest_random(100) < zopt_killrate)
                za[0].za_kill -= ztest_random(zopt_passtime * NANOSEC);

        for (t = 0; t < zopt_threads; t++) {
                d = t % zopt_datasets;

                (void) strcpy(za[t].za_pool, pool);
                za[t].za_os = za[d].za_os;
                za[t].za_spa = spa;
                za[t].za_zilog = za[d].za_zilog;
                za[t].za_instance = t;
                za[t].za_random = ztest_random(-1ULL);
                za[t].za_start = za[0].za_start;
                za[t].za_stop = za[0].za_stop;
                za[t].za_kill = za[0].za_kill;

                if (t < zopt_datasets) {
                        int test_future = FALSE;
                        (void) rw_rdlock(&ztest_shared->zs_name_lock);
                        (void) snprintf(name, 100, "%s/%s_%d", pool, pool, d);
                        error = dmu_objset_create(name, DMU_OST_OTHER, NULL, 0,
                            ztest_create_cb, NULL);
                        if (error == EEXIST) {
                                test_future = TRUE;
                        } else if (error == ENOSPC) {
                                zs->zs_enospc_count++;
                                (void) rw_unlock(&ztest_shared->zs_name_lock);
                                break;
                        } else if (error != 0) {
                                fatal(0, "dmu_objset_create(%s) = %d",
                                    name, error);
                        }
                        error = dmu_objset_open(name, DMU_OST_OTHER,
                            DS_MODE_USER, &za[d].za_os);
                        if (error)
                                fatal(0, "dmu_objset_open('%s') = %d",
                                    name, error);
                        (void) rw_unlock(&ztest_shared->zs_name_lock);
                        if (test_future)
                                ztest_dmu_check_future_leak(&za[t]);
                        zil_replay(za[d].za_os, za[d].za_os,
                            ztest_replay_vector);
                        za[d].za_zilog = zil_open(za[d].za_os, NULL);
                }

                VERIFY(thr_create(0, 0, ztest_thread, &za[t], THR_BOUND,
                    &za[t].za_thread) == 0);
        }

        while (--t >= 0) {
                VERIFY(thr_join(za[t].za_thread, NULL, NULL) == 0);
                if (t < zopt_datasets) {
                        zil_close(za[t].za_zilog);
                        dmu_objset_close(za[t].za_os);
                }
        }

        if (zopt_verbose >= 3)
                show_pool_stats(spa);

        txg_wait_synced(spa_get_dsl(spa), 0);

        zs->zs_alloc = spa_get_alloc(spa);
        zs->zs_space = spa_get_space(spa);

        /*
         * If we had out-of-space errors, destroy a random objset.
         */
        if (zs->zs_enospc_count != 0) {
                (void) rw_rdlock(&ztest_shared->zs_name_lock);
                d = (int)ztest_random(zopt_datasets);
                (void) snprintf(name, 100, "%s/%s_%d", pool, pool, d);
                if (zopt_verbose >= 3)
                        (void) printf("Destroying %s to free up space\n", name);

                /* Cleanup any non-standard clones and snapshots */
                ztest_dsl_dataset_cleanup(name, za[d].za_instance);

                (void) dmu_objset_find(name, ztest_destroy_cb, &za[d],
                    DS_FIND_SNAPSHOTS | DS_FIND_CHILDREN);
                (void) rw_unlock(&ztest_shared->zs_name_lock);
        }

        txg_wait_synced(spa_get_dsl(spa), 0);

        umem_free(za, zopt_threads * sizeof (ztest_args_t));

        /* Kill the resume thread */
        ztest_exiting = B_TRUE;
        VERIFY(thr_join(resume_tid, NULL, NULL) == 0);
        ztest_resume(spa);

        /*
         * Right before closing the pool, kick off a bunch of async I/O;
         * spa_close() should wait for it to complete.
         */
        for (t = 1; t < 50; t++)
                dmu_prefetch(spa->spa_meta_objset, t, 0, 1 << 15);

        spa_close(spa, FTAG);

        kernel_fini();
}

void
print_time(hrtime_t t, char *timebuf)
{
        hrtime_t s = t / NANOSEC;
        hrtime_t m = s / 60;
        hrtime_t h = m / 60;
        hrtime_t d = h / 24;

        s -= m * 60;
        m -= h * 60;
        h -= d * 24;

        timebuf[0] = '\0';

        if (d)
                (void) sprintf(timebuf,
                    "%llud%02lluh%02llum%02llus", d, h, m, s);
        else if (h)
                (void) sprintf(timebuf, "%lluh%02llum%02llus", h, m, s);
        else if (m)
                (void) sprintf(timebuf, "%llum%02llus", m, s);
        else
                (void) sprintf(timebuf, "%llus", s);
}

/*
 * Create a storage pool with the given name and initial vdev size.
 * Then create the specified number of datasets in the pool.
 */
static void
ztest_init(char *pool)
{
        spa_t *spa;
        int error;
        nvlist_t *nvroot;

        kernel_init(FREAD | FWRITE);

        /*
         * Create the storage pool.
         */
        (void) spa_destroy(pool);
        ztest_shared->zs_vdev_primaries = 0;
        nvroot = make_vdev_root(NULL, NULL, zopt_vdev_size, 0,
            0, zopt_raidz, zopt_mirrors, 1);
        error = spa_create(pool, nvroot, NULL, NULL, NULL);
        nvlist_free(nvroot);

        if (error)
                fatal(0, "spa_create() = %d", error);
        error = spa_open(pool, &spa, FTAG);
        if (error)
                fatal(0, "spa_open() = %d", error);

        metaslab_sz = 1ULL << spa->spa_root_vdev->vdev_child[0]->vdev_ms_shift;

        if (zopt_verbose >= 3)
                show_pool_stats(spa);

        spa_close(spa, FTAG);

        kernel_fini();
}

int
main(int argc, char **argv)
{
        int kills = 0;
        int iters = 0;
        int i, f;
        ztest_shared_t *zs;
        ztest_info_t *zi;
        char timebuf[100];
        char numbuf[6];

        (void) setvbuf(stdout, NULL, _IOLBF, 0);

        /* Override location of zpool.cache */
        spa_config_path = "/tmp/zpool.cache";

        ztest_random_fd = open("/dev/urandom", O_RDONLY);

        process_options(argc, argv);

        /*
         * Blow away any existing copy of zpool.cache
         */
        if (zopt_init != 0)
                (void) remove("/tmp/zpool.cache");

        zs = ztest_shared = (void *)mmap(0,
            P2ROUNDUP(sizeof (ztest_shared_t), getpagesize()),
            PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);

        if (zopt_verbose >= 1) {
                (void) printf("%llu vdevs, %d datasets, %d threads,"
                    " %llu seconds...\n",
                    (u_longlong_t)zopt_vdevs, zopt_datasets, zopt_threads,
                    (u_longlong_t)zopt_time);
        }

        /*
         * Create and initialize our storage pool.
         */
        for (i = 1; i <= zopt_init; i++) {
                bzero(zs, sizeof (ztest_shared_t));
                if (zopt_verbose >= 3 && zopt_init != 1)
                        (void) printf("ztest_init(), pass %d\n", i);
                ztest_init(zopt_pool);
        }

        /*
         * Initialize the call targets for each function.
         */
        for (f = 0; f < ZTEST_FUNCS; f++) {
                zi = &zs->zs_info[f];

                *zi = ztest_info[f];

                if (*zi->zi_interval == 0)
                        zi->zi_call_target = UINT64_MAX;
                else
                        zi->zi_call_target = zopt_time / *zi->zi_interval;
        }

        zs->zs_start_time = gethrtime();
        zs->zs_stop_time = zs->zs_start_time + zopt_time * NANOSEC;

        /*
         * Run the tests in a loop.  These tests include fault injection
         * to verify that self-healing data works, and forced crashes
         * to verify that we never lose on-disk consistency.
         */
        while (gethrtime() < zs->zs_stop_time) {
                int status;
                pid_t pid;
                char *tmp;

                /*
                 * Initialize the workload counters for each function.
                 */
                for (f = 0; f < ZTEST_FUNCS; f++) {
                        zi = &zs->zs_info[f];
                        zi->zi_calls = 0;
                        zi->zi_call_time = 0;
                }

                /* Set the allocation switch size */
                metaslab_df_alloc_threshold = ztest_random(metaslab_sz / 4) + 1;

                pid = fork();

                if (pid == -1)
                        fatal(1, "fork failed");

                if (pid == 0) { /* child */
                        struct rlimit rl = { 1024, 1024 };
                        (void) setrlimit(RLIMIT_NOFILE, &rl);
                        (void) enable_extended_FILE_stdio(-1, -1);
                        ztest_run(zopt_pool);
                        exit(0);
                }

                while (waitpid(pid, &status, 0) != pid)
                        continue;

                if (WIFEXITED(status)) {
                        if (WEXITSTATUS(status) != 0) {
                                (void) fprintf(stderr,
                                    "child exited with code %d\n",
                                    WEXITSTATUS(status));
                                exit(2);
                        }
                } else if (WIFSIGNALED(status)) {
                        if (WTERMSIG(status) != SIGKILL) {
                                (void) fprintf(stderr,
                                    "child died with signal %d\n",
                                    WTERMSIG(status));
                                exit(3);
                        }
                        kills++;
                } else {
                        (void) fprintf(stderr, "something strange happened "
                            "to child\n");
                        exit(4);
                }

                iters++;

                if (zopt_verbose >= 1) {
                        hrtime_t now = gethrtime();

                        now = MIN(now, zs->zs_stop_time);
                        print_time(zs->zs_stop_time - now, timebuf);
                        nicenum(zs->zs_space, numbuf);

                        (void) printf("Pass %3d, %8s, %3llu ENOSPC, "
                            "%4.1f%% of %5s used, %3.0f%% done, %8s to go\n",
                            iters,
                            WIFEXITED(status) ? "Complete" : "SIGKILL",
                            (u_longlong_t)zs->zs_enospc_count,
                            100.0 * zs->zs_alloc / zs->zs_space,
                            numbuf,
                            100.0 * (now - zs->zs_start_time) /
                            (zopt_time * NANOSEC), timebuf);
                }

                if (zopt_verbose >= 2) {
                        (void) printf("\nWorkload summary:\n\n");
                        (void) printf("%7s %9s   %s\n",
                            "Calls", "Time", "Function");
                        (void) printf("%7s %9s   %s\n",
                            "-----", "----", "--------");
                        for (f = 0; f < ZTEST_FUNCS; f++) {
                                Dl_info dli;

                                zi = &zs->zs_info[f];
                                print_time(zi->zi_call_time, timebuf);
                                (void) dladdr((void *)zi->zi_func, &dli);
                                (void) printf("%7llu %9s   %s\n",
                                    (u_longlong_t)zi->zi_calls, timebuf,
                                    dli.dli_sname);
                        }
                        (void) printf("\n");
                }

                /*
                 * It's possible that we killed a child during a rename test, in
                 * which case we'll have a 'ztest_tmp' pool lying around instead
                 * of 'ztest'.  Do a blind rename in case this happened.
                 */
                tmp = umem_alloc(strlen(zopt_pool) + 5, UMEM_NOFAIL);
                (void) strcpy(tmp, zopt_pool);
                (void) strcat(tmp, "_tmp");
                kernel_init(FREAD | FWRITE);
                (void) spa_rename(tmp, zopt_pool);
                kernel_fini();
                umem_free(tmp, strlen(tmp) + 1);
        }

        ztest_verify_blocks(zopt_pool);

        if (zopt_verbose >= 1) {
                (void) printf("%d killed, %d completed, %.0f%% kill rate\n",
                    kills, iters - kills, (100.0 * kills) / MAX(1, iters));
        }

        return (0);
}