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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), 2);
                  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, B_FALSE, 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_rsize(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_rsize(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);
}

/*
 * Verify that dynamic LUN growth works as expected.
 */
void
ztest_vdev_LUN_growth(ztest_args_t *za)
{
      spa_t *spa = za->za_spa;
      char dev_name[MAXPATHLEN];
      uint64_t leaves = MAX(zopt_mirrors, 1) * zopt_raidz;
      uint64_t vdev;
      size_t fsize;
      int fd;

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

      /*
       * Pick a random leaf vdev.
       */
      spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);
      vdev = ztest_random(spa->spa_root_vdev->vdev_children * leaves);
      spa_config_exit(spa, SCL_VDEV, FTAG);

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

      if ((fd = open(dev_name, O_RDWR)) != -1) {
            /*
             * Determine the size.
             */
            fsize = lseek(fd, 0, SEEK_END);

            /*
             * If it's less than 2x the original size, grow by around 3%.
             */
            if (fsize < 2 * zopt_vdev_size) {
                  size_t newsize = fsize + ztest_random(fsize / 32);
                  (void) ftruncate(fd, newsize);
                  if (zopt_verbose >= 6) {
                        (void) printf("%s grew from %lu to %lu bytes\n",
                            dev_name, (ulong_t)fsize, (ulong_t)newsize);
                  }
            }
            (void) close(fd);
      }

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

      error = dmu_objset_destroy(clone2name);
      if (error && error != ENOENT)
            fatal(0, "dmu_objset_destroy(%s) = %d", clone2name, error);
      error = dmu_objset_destroy(snap3name);
      if (error && error != ENOENT)
            fatal(0, "dmu_objset_destroy(%s) = %d", snap3name, error);
      error = dmu_objset_destroy(snap2name);
      if (error && error != ENOENT)
            fatal(0, "dmu_objset_destroy(%s) = %d", snap2name, error);
      error = dmu_objset_destroy(clone1name);
      if (error && error != ENOENT)
            fatal(0, "dmu_objset_destroy(%s) = %d", clone1name, error);
      error = dmu_objset_destroy(snap1name);
      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, (long long unsigned int) curval);
      (void) snprintf(clone1name, 100, "%s/c1_%llu", osname, (long long unsigned int) curval);
      (void) snprintf(snap2name, 100, "%s@s2_%llu", clone1name, (long long unsigned int) curval);
      (void) snprintf(clone2name, 100, "%s/c2_%llu", osname, (long long unsigned int) curval);
      (void) snprintf(snap3name, 100, "%s@s3_%llu", clone1name, (long long unsigned int) 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];  
      FILE *fp;   

      /* zfs-fuse: ztest is never installed, so zdb should be in ../zdb/ */
      /* LINTED */      

      (void) sprintf(zdb,
          "../zdb/zdb -bc%s%s -U /tmp/zpool.cache  %s",
          zopt_verbose >= 3 ? "s" : "",
          zopt_verbose >= 4 ? "v" : "",
          pool);

      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);
}

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