xref: /freebsd/sys/contrib/openzfs/cmd/zhack.c (revision 657729a89dd578d8cfc70d6616f5c65a48a8b33a)
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 <stdio.h>
34 #include <stdlib.h>
35 #include <ctype.h>
36 #include <sys/stat.h>
37 #include <sys/zfs_context.h>
38 #include <sys/spa.h>
39 #include <sys/spa_impl.h>
40 #include <sys/dmu.h>
41 #include <sys/zap.h>
42 #include <sys/zfs_znode.h>
43 #include <sys/dsl_synctask.h>
44 #include <sys/vdev.h>
45 #include <sys/vdev_impl.h>
46 #include <sys/fs/zfs.h>
47 #include <sys/dmu_objset.h>
48 #include <sys/dsl_pool.h>
49 #include <sys/zio_checksum.h>
50 #include <sys/zio_compress.h>
51 #include <sys/zfeature.h>
52 #include <sys/dmu_tx.h>
53 #include <zfeature_common.h>
54 #include <libzutil.h>
55 
56 static importargs_t g_importargs;
57 static char *g_pool;
58 static boolean_t g_readonly;
59 
60 static __attribute__((noreturn)) void
61 usage(void)
62 {
63 	(void) fprintf(stderr,
64 	    "Usage: zhack [-c cachefile] [-d dir] <subcommand> <args> ...\n"
65 	    "where <subcommand> <args> is one of the following:\n"
66 	    "\n");
67 
68 	(void) fprintf(stderr,
69 	    "    feature stat <pool>\n"
70 	    "        print information about enabled features\n"
71 	    "    feature enable [-r] [-d desc] <pool> <feature>\n"
72 	    "        add a new enabled feature to the pool\n"
73 	    "        -d <desc> sets the feature's description\n"
74 	    "        -r set read-only compatible flag for feature\n"
75 	    "    feature ref [-md] <pool> <feature>\n"
76 	    "        change the refcount on the given feature\n"
77 	    "        -d decrease instead of increase the refcount\n"
78 	    "        -m add the feature to the label if increasing refcount\n"
79 	    "\n"
80 	    "    <feature> : should be a feature guid\n"
81 	    "\n"
82 	    "    label repair <device>\n"
83 	    "        repair corrupted label checksums\n"
84 	    "\n"
85 	    "    <device> : path to vdev\n");
86 	exit(1);
87 }
88 
89 
90 static __attribute__((format(printf, 3, 4))) __attribute__((noreturn)) void
91 fatal(spa_t *spa, const void *tag, const char *fmt, ...)
92 {
93 	va_list ap;
94 
95 	if (spa != NULL) {
96 		spa_close(spa, tag);
97 		(void) spa_export(g_pool, NULL, B_TRUE, B_FALSE);
98 	}
99 
100 	va_start(ap, fmt);
101 	(void) fputs("zhack: ", stderr);
102 	(void) vfprintf(stderr, fmt, ap);
103 	va_end(ap);
104 	(void) fputc('\n', stderr);
105 
106 	exit(1);
107 }
108 
109 static int
110 space_delta_cb(dmu_object_type_t bonustype, const void *data,
111     zfs_file_info_t *zoi)
112 {
113 	(void) data, (void) zoi;
114 
115 	/*
116 	 * Is it a valid type of object to track?
117 	 */
118 	if (bonustype != DMU_OT_ZNODE && bonustype != DMU_OT_SA)
119 		return (ENOENT);
120 	(void) fprintf(stderr, "modifying object that needs user accounting");
121 	abort();
122 }
123 
124 /*
125  * Target is the dataset whose pool we want to open.
126  */
127 static void
128 zhack_import(char *target, boolean_t readonly)
129 {
130 	nvlist_t *config;
131 	nvlist_t *props;
132 	int error;
133 
134 	kernel_init(readonly ? SPA_MODE_READ :
135 	    (SPA_MODE_READ | SPA_MODE_WRITE));
136 
137 	dmu_objset_register_type(DMU_OST_ZFS, space_delta_cb);
138 
139 	g_readonly = readonly;
140 	g_importargs.can_be_active = readonly;
141 	g_pool = strdup(target);
142 
143 	libpc_handle_t lpch = {
144 		.lpc_lib_handle = NULL,
145 		.lpc_ops = &libzpool_config_ops,
146 		.lpc_printerr = B_TRUE
147 	};
148 	error = zpool_find_config(&lpch, target, &config, &g_importargs);
149 	if (error)
150 		fatal(NULL, FTAG, "cannot import '%s'", target);
151 
152 	props = NULL;
153 	if (readonly) {
154 		VERIFY(nvlist_alloc(&props, NV_UNIQUE_NAME, 0) == 0);
155 		VERIFY(nvlist_add_uint64(props,
156 		    zpool_prop_to_name(ZPOOL_PROP_READONLY), 1) == 0);
157 	}
158 
159 	zfeature_checks_disable = B_TRUE;
160 	error = spa_import(target, config, props,
161 	    (readonly ?  ZFS_IMPORT_SKIP_MMP : ZFS_IMPORT_NORMAL));
162 	fnvlist_free(config);
163 	zfeature_checks_disable = B_FALSE;
164 	if (error == EEXIST)
165 		error = 0;
166 
167 	if (error)
168 		fatal(NULL, FTAG, "can't import '%s': %s", target,
169 		    strerror(error));
170 }
171 
172 static void
173 zhack_spa_open(char *target, boolean_t readonly, const void *tag, spa_t **spa)
174 {
175 	int err;
176 
177 	zhack_import(target, readonly);
178 
179 	zfeature_checks_disable = B_TRUE;
180 	err = spa_open(target, spa, tag);
181 	zfeature_checks_disable = B_FALSE;
182 
183 	if (err != 0)
184 		fatal(*spa, FTAG, "cannot open '%s': %s", target,
185 		    strerror(err));
186 	if (spa_version(*spa) < SPA_VERSION_FEATURES) {
187 		fatal(*spa, FTAG, "'%s' has version %d, features not enabled",
188 		    target, (int)spa_version(*spa));
189 	}
190 }
191 
192 static void
193 dump_obj(objset_t *os, uint64_t obj, const char *name)
194 {
195 	zap_cursor_t zc;
196 	zap_attribute_t za;
197 
198 	(void) printf("%s_obj:\n", name);
199 
200 	for (zap_cursor_init(&zc, os, obj);
201 	    zap_cursor_retrieve(&zc, &za) == 0;
202 	    zap_cursor_advance(&zc)) {
203 		if (za.za_integer_length == 8) {
204 			ASSERT(za.za_num_integers == 1);
205 			(void) printf("\t%s = %llu\n",
206 			    za.za_name, (u_longlong_t)za.za_first_integer);
207 		} else {
208 			ASSERT(za.za_integer_length == 1);
209 			char val[1024];
210 			VERIFY(zap_lookup(os, obj, za.za_name,
211 			    1, sizeof (val), val) == 0);
212 			(void) printf("\t%s = %s\n", za.za_name, val);
213 		}
214 	}
215 	zap_cursor_fini(&zc);
216 }
217 
218 static void
219 dump_mos(spa_t *spa)
220 {
221 	nvlist_t *nv = spa->spa_label_features;
222 	nvpair_t *pair;
223 
224 	(void) printf("label config:\n");
225 	for (pair = nvlist_next_nvpair(nv, NULL);
226 	    pair != NULL;
227 	    pair = nvlist_next_nvpair(nv, pair)) {
228 		(void) printf("\t%s\n", nvpair_name(pair));
229 	}
230 }
231 
232 static void
233 zhack_do_feature_stat(int argc, char **argv)
234 {
235 	spa_t *spa;
236 	objset_t *os;
237 	char *target;
238 
239 	argc--;
240 	argv++;
241 
242 	if (argc < 1) {
243 		(void) fprintf(stderr, "error: missing pool name\n");
244 		usage();
245 	}
246 	target = argv[0];
247 
248 	zhack_spa_open(target, B_TRUE, FTAG, &spa);
249 	os = spa->spa_meta_objset;
250 
251 	dump_obj(os, spa->spa_feat_for_read_obj, "for_read");
252 	dump_obj(os, spa->spa_feat_for_write_obj, "for_write");
253 	dump_obj(os, spa->spa_feat_desc_obj, "descriptions");
254 	if (spa_feature_is_active(spa, SPA_FEATURE_ENABLED_TXG)) {
255 		dump_obj(os, spa->spa_feat_enabled_txg_obj, "enabled_txg");
256 	}
257 	dump_mos(spa);
258 
259 	spa_close(spa, FTAG);
260 }
261 
262 static void
263 zhack_feature_enable_sync(void *arg, dmu_tx_t *tx)
264 {
265 	spa_t *spa = dmu_tx_pool(tx)->dp_spa;
266 	zfeature_info_t *feature = arg;
267 
268 	feature_enable_sync(spa, feature, tx);
269 
270 	spa_history_log_internal(spa, "zhack enable feature", tx,
271 	    "name=%s flags=%u",
272 	    feature->fi_guid, feature->fi_flags);
273 }
274 
275 static void
276 zhack_do_feature_enable(int argc, char **argv)
277 {
278 	int c;
279 	char *desc, *target;
280 	spa_t *spa;
281 	objset_t *mos;
282 	zfeature_info_t feature;
283 	const spa_feature_t nodeps[] = { SPA_FEATURE_NONE };
284 
285 	/*
286 	 * Features are not added to the pool's label until their refcounts
287 	 * are incremented, so fi_mos can just be left as false for now.
288 	 */
289 	desc = NULL;
290 	feature.fi_uname = "zhack";
291 	feature.fi_flags = 0;
292 	feature.fi_depends = nodeps;
293 	feature.fi_feature = SPA_FEATURE_NONE;
294 
295 	optind = 1;
296 	while ((c = getopt(argc, argv, "+rd:")) != -1) {
297 		switch (c) {
298 		case 'r':
299 			feature.fi_flags |= ZFEATURE_FLAG_READONLY_COMPAT;
300 			break;
301 		case 'd':
302 			if (desc != NULL)
303 				free(desc);
304 			desc = strdup(optarg);
305 			break;
306 		default:
307 			usage();
308 			break;
309 		}
310 	}
311 
312 	if (desc == NULL)
313 		desc = strdup("zhack injected");
314 	feature.fi_desc = desc;
315 
316 	argc -= optind;
317 	argv += optind;
318 
319 	if (argc < 2) {
320 		(void) fprintf(stderr, "error: missing feature or pool name\n");
321 		usage();
322 	}
323 	target = argv[0];
324 	feature.fi_guid = argv[1];
325 
326 	if (!zfeature_is_valid_guid(feature.fi_guid))
327 		fatal(NULL, FTAG, "invalid feature guid: %s", feature.fi_guid);
328 
329 	zhack_spa_open(target, B_FALSE, FTAG, &spa);
330 	mos = spa->spa_meta_objset;
331 
332 	if (zfeature_is_supported(feature.fi_guid))
333 		fatal(spa, FTAG, "'%s' is a real feature, will not enable",
334 		    feature.fi_guid);
335 	if (0 == zap_contains(mos, spa->spa_feat_desc_obj, feature.fi_guid))
336 		fatal(spa, FTAG, "feature already enabled: %s",
337 		    feature.fi_guid);
338 
339 	VERIFY0(dsl_sync_task(spa_name(spa), NULL,
340 	    zhack_feature_enable_sync, &feature, 5, ZFS_SPACE_CHECK_NORMAL));
341 
342 	spa_close(spa, FTAG);
343 
344 	free(desc);
345 }
346 
347 static void
348 feature_incr_sync(void *arg, dmu_tx_t *tx)
349 {
350 	spa_t *spa = dmu_tx_pool(tx)->dp_spa;
351 	zfeature_info_t *feature = arg;
352 	uint64_t refcount;
353 
354 	VERIFY0(feature_get_refcount_from_disk(spa, feature, &refcount));
355 	feature_sync(spa, feature, refcount + 1, tx);
356 	spa_history_log_internal(spa, "zhack feature incr", tx,
357 	    "name=%s", feature->fi_guid);
358 }
359 
360 static void
361 feature_decr_sync(void *arg, dmu_tx_t *tx)
362 {
363 	spa_t *spa = dmu_tx_pool(tx)->dp_spa;
364 	zfeature_info_t *feature = arg;
365 	uint64_t refcount;
366 
367 	VERIFY0(feature_get_refcount_from_disk(spa, feature, &refcount));
368 	feature_sync(spa, feature, refcount - 1, tx);
369 	spa_history_log_internal(spa, "zhack feature decr", tx,
370 	    "name=%s", feature->fi_guid);
371 }
372 
373 static void
374 zhack_do_feature_ref(int argc, char **argv)
375 {
376 	int c;
377 	char *target;
378 	boolean_t decr = B_FALSE;
379 	spa_t *spa;
380 	objset_t *mos;
381 	zfeature_info_t feature;
382 	const spa_feature_t nodeps[] = { SPA_FEATURE_NONE };
383 
384 	/*
385 	 * fi_desc does not matter here because it was written to disk
386 	 * when the feature was enabled, but we need to properly set the
387 	 * feature for read or write based on the information we read off
388 	 * disk later.
389 	 */
390 	feature.fi_uname = "zhack";
391 	feature.fi_flags = 0;
392 	feature.fi_desc = NULL;
393 	feature.fi_depends = nodeps;
394 	feature.fi_feature = SPA_FEATURE_NONE;
395 
396 	optind = 1;
397 	while ((c = getopt(argc, argv, "+md")) != -1) {
398 		switch (c) {
399 		case 'm':
400 			feature.fi_flags |= ZFEATURE_FLAG_MOS;
401 			break;
402 		case 'd':
403 			decr = B_TRUE;
404 			break;
405 		default:
406 			usage();
407 			break;
408 		}
409 	}
410 	argc -= optind;
411 	argv += optind;
412 
413 	if (argc < 2) {
414 		(void) fprintf(stderr, "error: missing feature or pool name\n");
415 		usage();
416 	}
417 	target = argv[0];
418 	feature.fi_guid = argv[1];
419 
420 	if (!zfeature_is_valid_guid(feature.fi_guid))
421 		fatal(NULL, FTAG, "invalid feature guid: %s", feature.fi_guid);
422 
423 	zhack_spa_open(target, B_FALSE, FTAG, &spa);
424 	mos = spa->spa_meta_objset;
425 
426 	if (zfeature_is_supported(feature.fi_guid)) {
427 		fatal(spa, FTAG,
428 		    "'%s' is a real feature, will not change refcount",
429 		    feature.fi_guid);
430 	}
431 
432 	if (0 == zap_contains(mos, spa->spa_feat_for_read_obj,
433 	    feature.fi_guid)) {
434 		feature.fi_flags &= ~ZFEATURE_FLAG_READONLY_COMPAT;
435 	} else if (0 == zap_contains(mos, spa->spa_feat_for_write_obj,
436 	    feature.fi_guid)) {
437 		feature.fi_flags |= ZFEATURE_FLAG_READONLY_COMPAT;
438 	} else {
439 		fatal(spa, FTAG, "feature is not enabled: %s", feature.fi_guid);
440 	}
441 
442 	if (decr) {
443 		uint64_t count;
444 		if (feature_get_refcount_from_disk(spa, &feature,
445 		    &count) == 0 && count == 0) {
446 			fatal(spa, FTAG, "feature refcount already 0: %s",
447 			    feature.fi_guid);
448 		}
449 	}
450 
451 	VERIFY0(dsl_sync_task(spa_name(spa), NULL,
452 	    decr ? feature_decr_sync : feature_incr_sync, &feature,
453 	    5, ZFS_SPACE_CHECK_NORMAL));
454 
455 	spa_close(spa, FTAG);
456 }
457 
458 static int
459 zhack_do_feature(int argc, char **argv)
460 {
461 	char *subcommand;
462 
463 	argc--;
464 	argv++;
465 	if (argc == 0) {
466 		(void) fprintf(stderr,
467 		    "error: no feature operation specified\n");
468 		usage();
469 	}
470 
471 	subcommand = argv[0];
472 	if (strcmp(subcommand, "stat") == 0) {
473 		zhack_do_feature_stat(argc, argv);
474 	} else if (strcmp(subcommand, "enable") == 0) {
475 		zhack_do_feature_enable(argc, argv);
476 	} else if (strcmp(subcommand, "ref") == 0) {
477 		zhack_do_feature_ref(argc, argv);
478 	} else {
479 		(void) fprintf(stderr, "error: unknown subcommand: %s\n",
480 		    subcommand);
481 		usage();
482 	}
483 
484 	return (0);
485 }
486 
487 static int
488 zhack_repair_label_cksum(int argc, char **argv)
489 {
490 	zio_checksum_info_t *ci = &zio_checksum_table[ZIO_CHECKSUM_LABEL];
491 	const char *cfg_keys[] = { ZPOOL_CONFIG_VERSION,
492 	    ZPOOL_CONFIG_POOL_STATE, ZPOOL_CONFIG_GUID };
493 	boolean_t labels_repaired[VDEV_LABELS] = {0};
494 	boolean_t repaired = B_FALSE;
495 	vdev_label_t labels[VDEV_LABELS] = {{{0}}};
496 	struct stat st;
497 	int fd;
498 
499 	abd_init();
500 
501 	argc -= 1;
502 	argv += 1;
503 
504 	if (argc < 1) {
505 		(void) fprintf(stderr, "error: missing device\n");
506 		usage();
507 	}
508 
509 	if ((fd = open(argv[0], O_RDWR)) == -1)
510 		fatal(NULL, FTAG, "cannot open '%s': %s", argv[0],
511 		    strerror(errno));
512 
513 	if (stat(argv[0], &st) != 0)
514 		fatal(NULL, FTAG, "cannot stat '%s': %s", argv[0],
515 		    strerror(errno));
516 
517 	for (int l = 0; l < VDEV_LABELS; l++) {
518 		uint64_t label_offset, offset;
519 		zio_cksum_t expected_cksum;
520 		zio_cksum_t actual_cksum;
521 		zio_cksum_t verifier;
522 		zio_eck_t *eck;
523 		nvlist_t *cfg;
524 		int byteswap;
525 		uint64_t val;
526 		ssize_t err;
527 
528 		vdev_label_t *vl = &labels[l];
529 
530 		label_offset = vdev_label_offset(st.st_size, l, 0);
531 		err = pread64(fd, vl, sizeof (vdev_label_t), label_offset);
532 		if (err == -1) {
533 			(void) fprintf(stderr, "error: cannot read "
534 			    "label %d: %s\n", l, strerror(errno));
535 			continue;
536 		} else if (err != sizeof (vdev_label_t)) {
537 			(void) fprintf(stderr, "error: bad label %d read size "
538 			    "\n", l);
539 			continue;
540 		}
541 
542 		err = nvlist_unpack(vl->vl_vdev_phys.vp_nvlist,
543 		    VDEV_PHYS_SIZE - sizeof (zio_eck_t), &cfg, 0);
544 		if (err) {
545 			(void) fprintf(stderr, "error: cannot unpack nvlist "
546 			    "label %d\n", l);
547 			continue;
548 		}
549 
550 		for (int i = 0; i < ARRAY_SIZE(cfg_keys); i++) {
551 			err = nvlist_lookup_uint64(cfg, cfg_keys[i], &val);
552 			if (err) {
553 				(void) fprintf(stderr, "error: label %d: "
554 				    "cannot find nvlist key %s\n",
555 				    l, cfg_keys[i]);
556 				continue;
557 			}
558 		}
559 
560 		void *data = (char *)vl + offsetof(vdev_label_t, vl_vdev_phys);
561 		eck = (zio_eck_t *)((char *)(data) + VDEV_PHYS_SIZE) - 1;
562 
563 		offset = label_offset + offsetof(vdev_label_t, vl_vdev_phys);
564 		ZIO_SET_CHECKSUM(&verifier, offset, 0, 0, 0);
565 
566 		byteswap = (eck->zec_magic == BSWAP_64(ZEC_MAGIC));
567 		if (byteswap)
568 			byteswap_uint64_array(&verifier, sizeof (zio_cksum_t));
569 
570 		expected_cksum = eck->zec_cksum;
571 		eck->zec_cksum = verifier;
572 
573 		abd_t *abd = abd_get_from_buf(data, VDEV_PHYS_SIZE);
574 		ci->ci_func[byteswap](abd, VDEV_PHYS_SIZE, NULL, &actual_cksum);
575 		abd_free(abd);
576 
577 		if (byteswap)
578 			byteswap_uint64_array(&expected_cksum,
579 			    sizeof (zio_cksum_t));
580 
581 		if (ZIO_CHECKSUM_EQUAL(actual_cksum, expected_cksum))
582 			continue;
583 
584 		eck->zec_cksum = actual_cksum;
585 
586 		err = pwrite64(fd, data, VDEV_PHYS_SIZE, offset);
587 		if (err == -1) {
588 			(void) fprintf(stderr, "error: cannot write "
589 			    "label %d: %s\n", l, strerror(errno));
590 			continue;
591 		} else if (err != VDEV_PHYS_SIZE) {
592 			(void) fprintf(stderr, "error: bad write size "
593 			    "label %d\n", l);
594 			continue;
595 		}
596 
597 		fsync(fd);
598 
599 		labels_repaired[l] = B_TRUE;
600 	}
601 
602 	close(fd);
603 
604 	abd_fini();
605 
606 	for (int l = 0; l < VDEV_LABELS; l++) {
607 		(void) printf("label %d: %s\n", l,
608 		    labels_repaired[l] ? "repaired" : "skipped");
609 		repaired |= labels_repaired[l];
610 	}
611 
612 	if (repaired)
613 		return (0);
614 
615 	return (1);
616 }
617 
618 static int
619 zhack_do_label(int argc, char **argv)
620 {
621 	char *subcommand;
622 	int err;
623 
624 	argc--;
625 	argv++;
626 	if (argc == 0) {
627 		(void) fprintf(stderr,
628 		    "error: no label operation specified\n");
629 		usage();
630 	}
631 
632 	subcommand = argv[0];
633 	if (strcmp(subcommand, "repair") == 0) {
634 		err = zhack_repair_label_cksum(argc, argv);
635 	} else {
636 		(void) fprintf(stderr, "error: unknown subcommand: %s\n",
637 		    subcommand);
638 		usage();
639 	}
640 
641 	return (err);
642 }
643 
644 #define	MAX_NUM_PATHS 1024
645 
646 int
647 main(int argc, char **argv)
648 {
649 	extern void zfs_prop_init(void);
650 
651 	char *path[MAX_NUM_PATHS];
652 	const char *subcommand;
653 	int rv = 0;
654 	int c;
655 
656 	g_importargs.path = path;
657 
658 	dprintf_setup(&argc, argv);
659 	zfs_prop_init();
660 
661 	while ((c = getopt(argc, argv, "+c:d:")) != -1) {
662 		switch (c) {
663 		case 'c':
664 			g_importargs.cachefile = optarg;
665 			break;
666 		case 'd':
667 			assert(g_importargs.paths < MAX_NUM_PATHS);
668 			g_importargs.path[g_importargs.paths++] = optarg;
669 			break;
670 		default:
671 			usage();
672 			break;
673 		}
674 	}
675 
676 	argc -= optind;
677 	argv += optind;
678 	optind = 1;
679 
680 	if (argc == 0) {
681 		(void) fprintf(stderr, "error: no command specified\n");
682 		usage();
683 	}
684 
685 	subcommand = argv[0];
686 
687 	if (strcmp(subcommand, "feature") == 0) {
688 		rv = zhack_do_feature(argc, argv);
689 	} else if (strcmp(subcommand, "label") == 0) {
690 		return (zhack_do_label(argc, argv));
691 	} else {
692 		(void) fprintf(stderr, "error: unknown subcommand: %s\n",
693 		    subcommand);
694 		usage();
695 	}
696 
697 	if (!g_readonly && spa_export(g_pool, NULL, B_TRUE, B_FALSE) != 0) {
698 		fatal(NULL, FTAG, "pool export failed; "
699 		    "changes may not be committed to disk\n");
700 	}
701 
702 	kernel_fini();
703 
704 	return (rv);
705 }
706