cmd/zhack.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or https://opensource.org/licenses/CDDL-1.0.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
  24  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  25  */
  26
  27 /*
  28  * zhack is a debugging tool that can write changes to ZFS pool using libzpool
  29  * for testing purposes. Altering pools with zhack is unsupported and may
  30  * result in corrupted pools.
  31  */
  32
  33 #include <zfs_prop.h>
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <ctype.h>
  37 #include <sys/stat.h>
  38 #include <sys/zfs_context.h>
  39 #include <sys/spa.h>
  40 #include <sys/spa_impl.h>
  41 #include <sys/dmu.h>
  42 #include <sys/zap.h>
  43 #include <sys/zfs_znode.h>
  44 #include <sys/dsl_synctask.h>
  45 #include <sys/vdev.h>
  46 #include <sys/vdev_impl.h>
  47 #include <sys/fs/zfs.h>
  48 #include <sys/dmu_objset.h>
  49 #include <sys/dsl_pool.h>
  50 #include <sys/zio_checksum.h>
  51 #include <sys/zio_compress.h>
  52 #include <sys/zfeature.h>
  53 #include <sys/dmu_tx.h>
  54 #include <zfeature_common.h>
  55 #include <libzutil.h>
  56
  57 static importargs_t g_importargs;
  58 static char *g_pool;
  59 static boolean_t g_readonly;
  60
  61 static __attribute__((noreturn)) void
  62 usage(void)
  63 {
  64         (void) fprintf(stderr,
  65             "Usage: zhack [-c cachefile] [-d dir] <subcommand> <args> ...\n"
  66             "where <subcommand> <args> is one of the following:\n"
  67             "\n");
  68
  69         (void) fprintf(stderr,
  70             "    feature stat <pool>\n"
  71             "        print information about enabled features\n"
  72             "    feature enable [-r] [-d desc] <pool> <feature>\n"
  73             "        add a new enabled feature to the pool\n"
  74             "        -d <desc> sets the feature's description\n"
  75             "        -r set read-only compatible flag for feature\n"
  76             "    feature ref [-md] <pool> <feature>\n"
  77             "        change the refcount on the given feature\n"
  78             "        -d decrease instead of increase the refcount\n"
  79             "        -m add the feature to the label if increasing refcount\n"
  80             "\n"
  81             "    <feature> : should be a feature guid\n"
  82             "\n"
  83             "    label repair <device>\n"
  84             "        repair corrupted label checksums\n"
  85             "\n"
  86             "    <device> : path to vdev\n");
  87         exit(1);
  88 }
  89
  90
  91 static __attribute__((format(printf, 3, 4))) __attribute__((noreturn)) void
  92 fatal(spa_t *spa, const void *tag, const char *fmt, ...)
  93 {
  94         va_list ap;
  95
  96         if (spa != NULL) {
  97                 spa_close(spa, tag);
  98                 (void) spa_export(g_pool, NULL, B_TRUE, B_FALSE);
  99         }
 100
 101         va_start(ap, fmt);
 102         (void) fputs("zhack: ", stderr);
 103         (void) vfprintf(stderr, fmt, ap);
 104         va_end(ap);
 105         (void) fputc('\n', stderr);
 106
 107         exit(1);
 108 }
 109
 110 static int
 111 space_delta_cb(dmu_object_type_t bonustype, const void *data,
 112     zfs_file_info_t *zoi)
 113 {
 114         (void) data, (void) zoi;
 115
 116         /*
 117          * Is it a valid type of object to track?
 118          */
 119         if (bonustype != DMU_OT_ZNODE && bonustype != DMU_OT_SA)
 120                 return (ENOENT);
 121         (void) fprintf(stderr, "modifying object that needs user accounting");
 122         abort();
 123 }
 124
 125 /*
 126  * Target is the dataset whose pool we want to open.
 127  */
 128 static void
 129 zhack_import(char *target, boolean_t readonly)
 130 {
 131         nvlist_t *config;
 132         nvlist_t *props;
 133         int error;
 134
 135         kernel_init(readonly ? SPA_MODE_READ :
 136             (SPA_MODE_READ | SPA_MODE_WRITE));
 137
 138         dmu_objset_register_type(DMU_OST_ZFS, space_delta_cb);
 139
 140         g_readonly = readonly;
 141         g_importargs.can_be_active = readonly;
 142         g_pool = strdup(target);
 143
 144         libpc_handle_t lpch = {
 145                 .lpc_lib_handle = NULL,
 146                 .lpc_ops = &libzpool_config_ops,
 147                 .lpc_printerr = B_TRUE
 148         };
 149         error = zpool_find_config(&lpch, target, &config, &g_importargs);
 150         if (error)
 151                 fatal(NULL, FTAG, "cannot import '%s'", target);
 152
 153         props = NULL;
 154         if (readonly) {
 155                 VERIFY(nvlist_alloc(&props, NV_UNIQUE_NAME, 0) == 0);
 156                 VERIFY(nvlist_add_uint64(props,
 157                     zpool_prop_to_name(ZPOOL_PROP_READONLY), 1) == 0);
 158         }
 159
 160         zfeature_checks_disable = B_TRUE;
 161         error = spa_import(target, config, props,
 162             (readonly ?  ZFS_IMPORT_SKIP_MMP : ZFS_IMPORT_NORMAL));
 163         fnvlist_free(config);
 164         zfeature_checks_disable = B_FALSE;
 165         if (error == EEXIST)
 166                 error = 0;
 167
 168         if (error)
 169                 fatal(NULL, FTAG, "can't import '%s': %s", target,
 170                     strerror(error));
 171 }
 172
 173 static void
 174 zhack_spa_open(char *target, boolean_t readonly, const void *tag, spa_t **spa)
 175 {
 176         int err;
 177
 178         zhack_import(target, readonly);
 179
 180         zfeature_checks_disable = B_TRUE;
 181         err = spa_open(target, spa, tag);
 182         zfeature_checks_disable = B_FALSE;
 183
 184         if (err != 0)
 185                 fatal(*spa, FTAG, "cannot open '%s': %s", target,
 186                     strerror(err));
 187         if (spa_version(*spa) < SPA_VERSION_FEATURES) {
 188                 fatal(*spa, FTAG, "'%s' has version %d, features not enabled",
 189                     target, (int)spa_version(*spa));
 190         }
 191 }
 192
 193 static void
 194 dump_obj(objset_t *os, uint64_t obj, const char *name)
 195 {
 196         zap_cursor_t zc;
 197         zap_attribute_t za;
 198
 199         (void) printf("%s_obj:\n", name);
 200
 201         for (zap_cursor_init(&zc, os, obj);
 202             zap_cursor_retrieve(&zc, &za) == 0;
 203             zap_cursor_advance(&zc)) {
 204                 if (za.za_integer_length == 8) {
 205                         ASSERT(za.za_num_integers == 1);
 206                         (void) printf("\t%s = %llu\n",
 207                             za.za_name, (u_longlong_t)za.za_first_integer);
 208                 } else {
 209                         ASSERT(za.za_integer_length == 1);
 210                         char val[1024];
 211                         VERIFY(zap_lookup(os, obj, za.za_name,
 212                             1, sizeof (val), val) == 0);
 213                         (void) printf("\t%s = %s\n", za.za_name, val);
 214                 }
 215         }
 216         zap_cursor_fini(&zc);
 217 }
 218
 219 static void
 220 dump_mos(spa_t *spa)
 221 {
 222         nvlist_t *nv = spa->spa_label_features;
 223         nvpair_t *pair;
 224
 225         (void) printf("label config:\n");
 226         for (pair = nvlist_next_nvpair(nv, NULL);
 227             pair != NULL;
 228             pair = nvlist_next_nvpair(nv, pair)) {
 229                 (void) printf("\t%s\n", nvpair_name(pair));
 230         }
 231 }
 232
 233 static void
 234 zhack_do_feature_stat(int argc, char **argv)
 235 {
 236         spa_t *spa;
 237         objset_t *os;
 238         char *target;
 239
 240         argc--;
 241         argv++;
 242
 243         if (argc < 1) {
 244                 (void) fprintf(stderr, "error: missing pool name\n");
 245                 usage();
 246         }
 247         target = argv[0];
 248
 249         zhack_spa_open(target, B_TRUE, FTAG, &spa);
 250         os = spa->spa_meta_objset;
 251
 252         dump_obj(os, spa->spa_feat_for_read_obj, "for_read");
 253         dump_obj(os, spa->spa_feat_for_write_obj, "for_write");
 254         dump_obj(os, spa->spa_feat_desc_obj, "descriptions");
 255         if (spa_feature_is_active(spa, SPA_FEATURE_ENABLED_TXG)) {
 256                 dump_obj(os, spa->spa_feat_enabled_txg_obj, "enabled_txg");
 257         }
 258         dump_mos(spa);
 259
 260         spa_close(spa, FTAG);
 261 }
 262
 263 static void
 264 zhack_feature_enable_sync(void *arg, dmu_tx_t *tx)
 265 {
 266         spa_t *spa = dmu_tx_pool(tx)->dp_spa;
 267         zfeature_info_t *feature = arg;
 268
 269         feature_enable_sync(spa, feature, tx);
 270
 271         spa_history_log_internal(spa, "zhack enable feature", tx,
 272             "name=%s flags=%u",
 273             feature->fi_guid, feature->fi_flags);
 274 }
 275
 276 static void
 277 zhack_do_feature_enable(int argc, char **argv)
 278 {
 279         int c;
 280         char *desc, *target;
 281         spa_t *spa;
 282         objset_t *mos;
 283         zfeature_info_t feature;
 284         const spa_feature_t nodeps[] = { SPA_FEATURE_NONE };
 285
 286         /*
 287          * Features are not added to the pool's label until their refcounts
 288          * are incremented, so fi_mos can just be left as false for now.
 289          */
 290         desc = NULL;
 291         feature.fi_uname = "zhack";
 292         feature.fi_flags = 0;
 293         feature.fi_depends = nodeps;
 294         feature.fi_feature = SPA_FEATURE_NONE;
 295
 296         optind = 1;
 297         while ((c = getopt(argc, argv, "+rd:")) != -1) {
 298                 switch (c) {
 299                 case 'r':
 300                         feature.fi_flags |= ZFEATURE_FLAG_READONLY_COMPAT;
 301                         break;
 302                 case 'd':
 303                         if (desc != NULL)
 304                                 free(desc);
 305                         desc = strdup(optarg);
 306                         break;
 307                 default:
 308                         usage();
 309                         break;
 310                 }
 311         }
 312
 313         if (desc == NULL)
 314                 desc = strdup("zhack injected");
 315         feature.fi_desc = desc;
 316
 317         argc -= optind;
 318         argv += optind;
 319
 320         if (argc < 2) {
 321                 (void) fprintf(stderr, "error: missing feature or pool name\n");
 322                 usage();
 323         }
 324         target = argv[0];
 325         feature.fi_guid = argv[1];
 326
 327         if (!zfeature_is_valid_guid(feature.fi_guid))
 328                 fatal(NULL, FTAG, "invalid feature guid: %s", feature.fi_guid);
 329
 330         zhack_spa_open(target, B_FALSE, FTAG, &spa);
 331         mos = spa->spa_meta_objset;
 332
 333         if (zfeature_is_supported(feature.fi_guid))
 334                 fatal(spa, FTAG, "'%s' is a real feature, will not enable",
 335                     feature.fi_guid);
 336         if (0 == zap_contains(mos, spa->spa_feat_desc_obj, feature.fi_guid))
 337                 fatal(spa, FTAG, "feature already enabled: %s",
 338                     feature.fi_guid);
 339
 340         VERIFY0(dsl_sync_task(spa_name(spa), NULL,
 341             zhack_feature_enable_sync, &feature, 5, ZFS_SPACE_CHECK_NORMAL));
 342
 343         spa_close(spa, FTAG);
 344
 345         free(desc);
 346 }
 347
 348 static void
 349 feature_incr_sync(void *arg, dmu_tx_t *tx)
 350 {
 351         spa_t *spa = dmu_tx_pool(tx)->dp_spa;
 352         zfeature_info_t *feature = arg;
 353         uint64_t refcount;
 354
 355         VERIFY0(feature_get_refcount_from_disk(spa, feature, &refcount));
 356         feature_sync(spa, feature, refcount + 1, tx);
 357         spa_history_log_internal(spa, "zhack feature incr", tx,
 358             "name=%s", feature->fi_guid);
 359 }
 360
 361 static void
 362 feature_decr_sync(void *arg, dmu_tx_t *tx)
 363 {
 364         spa_t *spa = dmu_tx_pool(tx)->dp_spa;
 365         zfeature_info_t *feature = arg;
 366         uint64_t refcount;
 367
 368         VERIFY0(feature_get_refcount_from_disk(spa, feature, &refcount));
 369         feature_sync(spa, feature, refcount - 1, tx);
 370         spa_history_log_internal(spa, "zhack feature decr", tx,
 371             "name=%s", feature->fi_guid);
 372 }
 373
 374 static void
 375 zhack_do_feature_ref(int argc, char **argv)
 376 {
 377         int c;
 378         char *target;
 379         boolean_t decr = B_FALSE;
 380         spa_t *spa;
 381         objset_t *mos;
 382         zfeature_info_t feature;
 383         const spa_feature_t nodeps[] = { SPA_FEATURE_NONE };
 384
 385         /*
 386          * fi_desc does not matter here because it was written to disk
 387          * when the feature was enabled, but we need to properly set the
 388          * feature for read or write based on the information we read off
 389          * disk later.
 390          */
 391         feature.fi_uname = "zhack";
 392         feature.fi_flags = 0;
 393         feature.fi_desc = NULL;
 394         feature.fi_depends = nodeps;
 395         feature.fi_feature = SPA_FEATURE_NONE;
 396
 397         optind = 1;
 398         while ((c = getopt(argc, argv, "+md")) != -1) {
 399                 switch (c) {
 400                 case 'm':
 401                         feature.fi_flags |= ZFEATURE_FLAG_MOS;
 402                         break;
 403                 case 'd':
 404                         decr = B_TRUE;
 405                         break;
 406                 default:
 407                         usage();
 408                         break;
 409                 }
 410         }
 411         argc -= optind;
 412         argv += optind;
 413
 414         if (argc < 2) {
 415                 (void) fprintf(stderr, "error: missing feature or pool name\n");
 416                 usage();
 417         }
 418         target = argv[0];
 419         feature.fi_guid = argv[1];
 420
 421         if (!zfeature_is_valid_guid(feature.fi_guid))
 422                 fatal(NULL, FTAG, "invalid feature guid: %s", feature.fi_guid);
 423
 424         zhack_spa_open(target, B_FALSE, FTAG, &spa);
 425         mos = spa->spa_meta_objset;
 426
 427         if (zfeature_is_supported(feature.fi_guid)) {
 428                 fatal(spa, FTAG,
 429                     "'%s' is a real feature, will not change refcount",
 430                     feature.fi_guid);
 431         }
 432
 433         if (0 == zap_contains(mos, spa->spa_feat_for_read_obj,
 434             feature.fi_guid)) {
 435                 feature.fi_flags &= ~ZFEATURE_FLAG_READONLY_COMPAT;
 436         } else if (0 == zap_contains(mos, spa->spa_feat_for_write_obj,
 437             feature.fi_guid)) {
 438                 feature.fi_flags |= ZFEATURE_FLAG_READONLY_COMPAT;
 439         } else {
 440                 fatal(spa, FTAG, "feature is not enabled: %s", feature.fi_guid);
 441         }
 442
 443         if (decr) {
 444                 uint64_t count;
 445                 if (feature_get_refcount_from_disk(spa, &feature,
 446                     &count) == 0 && count == 0) {
 447                         fatal(spa, FTAG, "feature refcount already 0: %s",
 448                             feature.fi_guid);
 449                 }
 450         }
 451
 452         VERIFY0(dsl_sync_task(spa_name(spa), NULL,
 453             decr ? feature_decr_sync : feature_incr_sync, &feature,
 454             5, ZFS_SPACE_CHECK_NORMAL));
 455
 456         spa_close(spa, FTAG);
 457 }
 458
 459 static int
 460 zhack_do_feature(int argc, char **argv)
 461 {
 462         char *subcommand;
 463
 464         argc--;
 465         argv++;
 466         if (argc == 0) {
 467                 (void) fprintf(stderr,
 468                     "error: no feature operation specified\n");
 469                 usage();
 470         }
 471
 472         subcommand = argv[0];
 473         if (strcmp(subcommand, "stat") == 0) {
 474                 zhack_do_feature_stat(argc, argv);
 475         } else if (strcmp(subcommand, "enable") == 0) {
 476                 zhack_do_feature_enable(argc, argv);
 477         } else if (strcmp(subcommand, "ref") == 0) {
 478                 zhack_do_feature_ref(argc, argv);
 479         } else {
 480                 (void) fprintf(stderr, "error: unknown subcommand: %s\n",
 481                     subcommand);
 482                 usage();
 483         }
 484
 485         return (0);
 486 }
 487
 488 static int
 489 zhack_repair_label_cksum(int argc, char **argv)
 490 {
 491         zio_checksum_info_t *ci = &zio_checksum_table[ZIO_CHECKSUM_LABEL];
 492         const char *cfg_keys[] = { ZPOOL_CONFIG_VERSION,
 493             ZPOOL_CONFIG_POOL_STATE, ZPOOL_CONFIG_GUID };
 494         boolean_t labels_repaired[VDEV_LABELS] = {0};
 495         boolean_t repaired = B_FALSE;
 496         vdev_label_t labels[VDEV_LABELS] = {{{0}}};
 497         struct stat st;
 498         int fd;
 499
 500         abd_init();
 501
 502         argc -= 1;
 503         argv += 1;
 504
 505         if (argc < 1) {
 506                 (void) fprintf(stderr, "error: missing device\n");
 507                 usage();
 508         }
 509
 510         if ((fd = open(argv[0], O_RDWR)) == -1)
 511                 fatal(NULL, FTAG, "cannot open '%s': %s", argv[0],
 512                     strerror(errno));
 513
 514         if (stat(argv[0], &st) != 0)
 515                 fatal(NULL, FTAG, "cannot stat '%s': %s", argv[0],
 516                     strerror(errno));
 517
 518         for (int l = 0; l < VDEV_LABELS; l++) {
 519                 uint64_t label_offset, offset;
 520                 zio_cksum_t expected_cksum;
 521                 zio_cksum_t actual_cksum;
 522                 zio_cksum_t verifier;
 523                 zio_eck_t *eck;
 524                 nvlist_t *cfg;
 525                 int byteswap;
 526                 uint64_t val;
 527                 ssize_t err;
 528
 529                 vdev_label_t *vl = &labels[l];
 530
 531                 label_offset = vdev_label_offset(st.st_size, l, 0);
 532                 err = pread64(fd, vl, sizeof (vdev_label_t), label_offset);
 533                 if (err == -1) {
 534                         (void) fprintf(stderr, "error: cannot read "
 535                             "label %d: %s\n", l, strerror(errno));
 536                         continue;
 537                 } else if (err != sizeof (vdev_label_t)) {
 538                         (void) fprintf(stderr, "error: bad label %d read size "
 539                             "\n", l);
 540                         continue;
 541                 }
 542
 543                 err = nvlist_unpack(vl->vl_vdev_phys.vp_nvlist,
 544                     VDEV_PHYS_SIZE - sizeof (zio_eck_t), &cfg, 0);
 545                 if (err) {
 546                         (void) fprintf(stderr, "error: cannot unpack nvlist "
 547                             "label %d\n", l);
 548                         continue;
 549                 }
 550
 551                 for (int i = 0; i < ARRAY_SIZE(cfg_keys); i++) {
 552                         err = nvlist_lookup_uint64(cfg, cfg_keys[i], &val);
 553                         if (err) {
 554                                 (void) fprintf(stderr, "error: label %d: "
 555                                     "cannot find nvlist key %s\n",
 556                                     l, cfg_keys[i]);
 557                                 continue;
 558                         }
 559                 }
 560
 561                 void *data = (char *)vl + offsetof(vdev_label_t, vl_vdev_phys);
 562                 eck = (zio_eck_t *)((char *)(data) + VDEV_PHYS_SIZE) - 1;
 563
 564                 offset = label_offset + offsetof(vdev_label_t, vl_vdev_phys);
 565                 ZIO_SET_CHECKSUM(&verifier, offset, 0, 0, 0);
 566
 567                 byteswap = (eck->zec_magic == BSWAP_64(ZEC_MAGIC));
 568                 if (byteswap)
 569                         byteswap_uint64_array(&verifier, sizeof (zio_cksum_t));
 570
 571                 expected_cksum = eck->zec_cksum;
 572                 eck->zec_cksum = verifier;
 573
 574                 abd_t *abd = abd_get_from_buf(data, VDEV_PHYS_SIZE);
 575                 ci->ci_func[byteswap](abd, VDEV_PHYS_SIZE, NULL, &actual_cksum);
 576                 abd_free(abd);
 577
 578                 if (byteswap)
 579                         byteswap_uint64_array(&expected_cksum,
 580                             sizeof (zio_cksum_t));
 581
 582                 if (ZIO_CHECKSUM_EQUAL(actual_cksum, expected_cksum))
 583                         continue;
 584
 585                 eck->zec_cksum = actual_cksum;
 586
 587                 err = pwrite64(fd, data, VDEV_PHYS_SIZE, offset);
 588                 if (err == -1) {
 589                         (void) fprintf(stderr, "error: cannot write "
 590                             "label %d: %s\n", l, strerror(errno));
 591                         continue;
 592                 } else if (err != VDEV_PHYS_SIZE) {
 593                         (void) fprintf(stderr, "error: bad write size "
 594                             "label %d\n", l);
 595                         continue;
 596                 }
 597
 598                 fsync(fd);
 599
 600                 labels_repaired[l] = B_TRUE;
 601         }
 602
 603         close(fd);
 604
 605         abd_fini();
 606
 607         for (int l = 0; l < VDEV_LABELS; l++) {
 608                 (void) printf("label %d: %s\n", l,
 609                     labels_repaired[l] ? "repaired" : "skipped");
 610                 repaired |= labels_repaired[l];
 611         }
 612
 613         if (repaired)
 614                 return (0);
 615
 616         return (1);
 617 }
 618
 619 static int
 620 zhack_do_label(int argc, char **argv)
 621 {
 622         char *subcommand;
 623         int err;
 624
 625         argc--;
 626         argv++;
 627         if (argc == 0) {
 628                 (void) fprintf(stderr,
 629                     "error: no label operation specified\n");
 630                 usage();
 631         }
 632
 633         subcommand = argv[0];
 634         if (strcmp(subcommand, "repair") == 0) {
 635                 err = zhack_repair_label_cksum(argc, argv);
 636         } else {
 637                 (void) fprintf(stderr, "error: unknown subcommand: %s\n",
 638                     subcommand);
 639                 usage();
 640         }
 641
 642         return (err);
 643 }
 644
 645 #define MAX_NUM_PATHS 1024
 646
 647 int
 648 main(int argc, char **argv)
 649 {
 650         char *path[MAX_NUM_PATHS];
 651         const char *subcommand;
 652         int rv = 0;
 653         int c;
 654
 655         g_importargs.path = path;
 656
 657         dprintf_setup(&argc, argv);
 658         zfs_prop_init();
 659
 660         while ((c = getopt(argc, argv, "+c:d:")) != -1) {
 661                 switch (c) {
 662                 case 'c':
 663                         g_importargs.cachefile = optarg;
 664                         break;
 665                 case 'd':
 666                         assert(g_importargs.paths < MAX_NUM_PATHS);
 667                         g_importargs.path[g_importargs.paths++] = optarg;
 668                         break;
 669                 default:
 670                         usage();
 671                         break;
 672                 }
 673         }
 674
 675         argc -= optind;
 676         argv += optind;
 677         optind = 1;
 678
 679         if (argc == 0) {
 680                 (void) fprintf(stderr, "error: no command specified\n");
 681                 usage();
 682         }
 683
 684         subcommand = argv[0];
 685
 686         if (strcmp(subcommand, "feature") == 0) {
 687                 rv = zhack_do_feature(argc, argv);
 688         } else if (strcmp(subcommand, "label") == 0) {
 689                 return (zhack_do_label(argc, argv));
 690         } else {
 691                 (void) fprintf(stderr, "error: unknown subcommand: %s\n",
 692                     subcommand);
 693                 usage();
 694         }
 695
 696         if (!g_readonly && spa_export(g_pool, NULL, B_TRUE, B_FALSE) != 0) {
 697                 fatal(NULL, FTAG, "pool export failed; "
 698                     "changes may not be committed to disk\n");
 699         }
 700
 701         kernel_fini();
 702
 703         return (rv);
 704 }