xref: /freebsd/stand/libsa/zfs/zfsimpl.c (revision 734e82fe33aa764367791a7d603b383996c6b40b)
1 /*-
2  * Copyright (c) 2007 Doug Rabson
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 /*
29  *	Stand-alone ZFS file reader.
30  */
31 
32 #include <stdbool.h>
33 #include <sys/endian.h>
34 #include <sys/stat.h>
35 #include <sys/stdint.h>
36 #include <sys/list.h>
37 #include <sys/zfs_bootenv.h>
38 #include <machine/_inttypes.h>
39 
40 #include "zfsimpl.h"
41 #include "zfssubr.c"
42 
43 #ifdef HAS_ZSTD_ZFS
44 extern int zstd_init(void);
45 #endif
46 
47 struct zfsmount {
48 	char			*path;
49 	const spa_t		*spa;
50 	objset_phys_t		objset;
51 	uint64_t		rootobj;
52 	STAILQ_ENTRY(zfsmount)	next;
53 };
54 
55 typedef STAILQ_HEAD(zfs_mnt_list, zfsmount) zfs_mnt_list_t;
56 static zfs_mnt_list_t zfsmount = STAILQ_HEAD_INITIALIZER(zfsmount);
57 
58 /*
59  * The indirect_child_t represents the vdev that we will read from, when we
60  * need to read all copies of the data (e.g. for scrub or reconstruction).
61  * For plain (non-mirror) top-level vdevs (i.e. is_vdev is not a mirror),
62  * ic_vdev is the same as is_vdev.  However, for mirror top-level vdevs,
63  * ic_vdev is a child of the mirror.
64  */
65 typedef struct indirect_child {
66 	void *ic_data;
67 	vdev_t *ic_vdev;
68 } indirect_child_t;
69 
70 /*
71  * The indirect_split_t represents one mapped segment of an i/o to the
72  * indirect vdev. For non-split (contiguously-mapped) blocks, there will be
73  * only one indirect_split_t, with is_split_offset==0 and is_size==io_size.
74  * For split blocks, there will be several of these.
75  */
76 typedef struct indirect_split {
77 	list_node_t is_node; /* link on iv_splits */
78 
79 	/*
80 	 * is_split_offset is the offset into the i/o.
81 	 * This is the sum of the previous splits' is_size's.
82 	 */
83 	uint64_t is_split_offset;
84 
85 	vdev_t *is_vdev; /* top-level vdev */
86 	uint64_t is_target_offset; /* offset on is_vdev */
87 	uint64_t is_size;
88 	int is_children; /* number of entries in is_child[] */
89 
90 	/*
91 	 * is_good_child is the child that we are currently using to
92 	 * attempt reconstruction.
93 	 */
94 	int is_good_child;
95 
96 	indirect_child_t is_child[1]; /* variable-length */
97 } indirect_split_t;
98 
99 /*
100  * The indirect_vsd_t is associated with each i/o to the indirect vdev.
101  * It is the "Vdev-Specific Data" in the zio_t's io_vsd.
102  */
103 typedef struct indirect_vsd {
104 	boolean_t iv_split_block;
105 	boolean_t iv_reconstruct;
106 
107 	list_t iv_splits; /* list of indirect_split_t's */
108 } indirect_vsd_t;
109 
110 /*
111  * List of all vdevs, chained through v_alllink.
112  */
113 static vdev_list_t zfs_vdevs;
114 
115 /*
116  * List of ZFS features supported for read
117  */
118 static const char *features_for_read[] = {
119 	"com.datto:bookmark_v2",
120 	"com.datto:encryption",
121 	"com.datto:resilver_defer",
122 	"com.delphix:bookmark_written",
123 	"com.delphix:device_removal",
124 	"com.delphix:embedded_data",
125 	"com.delphix:extensible_dataset",
126 	"com.delphix:head_errlog",
127 	"com.delphix:hole_birth",
128 	"com.delphix:obsolete_counts",
129 	"com.delphix:spacemap_histogram",
130 	"com.delphix:spacemap_v2",
131 	"com.delphix:zpool_checkpoint",
132 	"com.intel:allocation_classes",
133 	"com.joyent:multi_vdev_crash_dump",
134 	"com.klarasystems:vdev_zaps_v2",
135 	"org.freebsd:zstd_compress",
136 	"org.illumos:lz4_compress",
137 	"org.illumos:sha512",
138 	"org.illumos:skein",
139 	"org.open-zfs:large_blocks",
140 	"org.openzfs:blake3",
141 	"org.zfsonlinux:allocation_classes",
142 	"org.zfsonlinux:large_dnode",
143 	NULL
144 };
145 
146 /*
147  * List of all pools, chained through spa_link.
148  */
149 static spa_list_t zfs_pools;
150 
151 static const dnode_phys_t *dnode_cache_obj;
152 static uint64_t dnode_cache_bn;
153 static char *dnode_cache_buf;
154 
155 static int zio_read(const spa_t *spa, const blkptr_t *bp, void *buf);
156 static int zfs_get_root(const spa_t *spa, uint64_t *objid);
157 static int zfs_rlookup(const spa_t *spa, uint64_t objnum, char *result);
158 static int zap_lookup(const spa_t *spa, const dnode_phys_t *dnode,
159     const char *name, uint64_t integer_size, uint64_t num_integers,
160     void *value);
161 static int objset_get_dnode(const spa_t *, const objset_phys_t *, uint64_t,
162     dnode_phys_t *);
163 static int dnode_read(const spa_t *, const dnode_phys_t *, off_t, void *,
164     size_t);
165 static int vdev_indirect_read(vdev_t *, const blkptr_t *, void *, off_t,
166     size_t);
167 static int vdev_mirror_read(vdev_t *, const blkptr_t *, void *, off_t, size_t);
168 vdev_indirect_mapping_t *vdev_indirect_mapping_open(spa_t *, objset_phys_t *,
169     uint64_t);
170 vdev_indirect_mapping_entry_phys_t *
171     vdev_indirect_mapping_duplicate_adjacent_entries(vdev_t *, uint64_t,
172     uint64_t, uint64_t *);
173 
174 static void
175 zfs_init(void)
176 {
177 	STAILQ_INIT(&zfs_vdevs);
178 	STAILQ_INIT(&zfs_pools);
179 
180 	dnode_cache_buf = malloc(SPA_MAXBLOCKSIZE);
181 
182 	zfs_init_crc();
183 #ifdef HAS_ZSTD_ZFS
184 	zstd_init();
185 #endif
186 }
187 
188 static int
189 nvlist_check_features_for_read(nvlist_t *nvl)
190 {
191 	nvlist_t *features = NULL;
192 	nvs_data_t *data;
193 	nvp_header_t *nvp;
194 	nv_string_t *nvp_name;
195 	int rc;
196 
197 	rc = nvlist_find(nvl, ZPOOL_CONFIG_FEATURES_FOR_READ,
198 	    DATA_TYPE_NVLIST, NULL, &features, NULL);
199 	switch (rc) {
200 	case 0:
201 		break;		/* Continue with checks */
202 
203 	case ENOENT:
204 		return (0);	/* All features are disabled */
205 
206 	default:
207 		return (rc);	/* Error while reading nvlist */
208 	}
209 
210 	data = (nvs_data_t *)features->nv_data;
211 	nvp = &data->nvl_pair;	/* first pair in nvlist */
212 
213 	while (nvp->encoded_size != 0 && nvp->decoded_size != 0) {
214 		int i, found;
215 
216 		nvp_name = (nv_string_t *)((uintptr_t)nvp + sizeof(*nvp));
217 		found = 0;
218 
219 		for (i = 0; features_for_read[i] != NULL; i++) {
220 			if (memcmp(nvp_name->nv_data, features_for_read[i],
221 			    nvp_name->nv_size) == 0) {
222 				found = 1;
223 				break;
224 			}
225 		}
226 
227 		if (!found) {
228 			printf("ZFS: unsupported feature: %.*s\n",
229 			    nvp_name->nv_size, nvp_name->nv_data);
230 			rc = EIO;
231 		}
232 		nvp = (nvp_header_t *)((uint8_t *)nvp + nvp->encoded_size);
233 	}
234 	nvlist_destroy(features);
235 
236 	return (rc);
237 }
238 
239 static int
240 vdev_read_phys(vdev_t *vdev, const blkptr_t *bp, void *buf,
241     off_t offset, size_t size)
242 {
243 	size_t psize;
244 	int rc;
245 
246 	if (vdev->v_phys_read == NULL)
247 		return (ENOTSUP);
248 
249 	if (bp) {
250 		psize = BP_GET_PSIZE(bp);
251 	} else {
252 		psize = size;
253 	}
254 
255 	rc = vdev->v_phys_read(vdev, vdev->v_priv, offset, buf, psize);
256 	if (rc == 0) {
257 		if (bp != NULL)
258 			rc = zio_checksum_verify(vdev->v_spa, bp, buf);
259 	}
260 
261 	return (rc);
262 }
263 
264 static int
265 vdev_write_phys(vdev_t *vdev, void *buf, off_t offset, size_t size)
266 {
267 	if (vdev->v_phys_write == NULL)
268 		return (ENOTSUP);
269 
270 	return (vdev->v_phys_write(vdev, offset, buf, size));
271 }
272 
273 typedef struct remap_segment {
274 	vdev_t *rs_vd;
275 	uint64_t rs_offset;
276 	uint64_t rs_asize;
277 	uint64_t rs_split_offset;
278 	list_node_t rs_node;
279 } remap_segment_t;
280 
281 static remap_segment_t *
282 rs_alloc(vdev_t *vd, uint64_t offset, uint64_t asize, uint64_t split_offset)
283 {
284 	remap_segment_t *rs = malloc(sizeof (remap_segment_t));
285 
286 	if (rs != NULL) {
287 		rs->rs_vd = vd;
288 		rs->rs_offset = offset;
289 		rs->rs_asize = asize;
290 		rs->rs_split_offset = split_offset;
291 	}
292 
293 	return (rs);
294 }
295 
296 vdev_indirect_mapping_t *
297 vdev_indirect_mapping_open(spa_t *spa, objset_phys_t *os,
298     uint64_t mapping_object)
299 {
300 	vdev_indirect_mapping_t *vim;
301 	vdev_indirect_mapping_phys_t *vim_phys;
302 	int rc;
303 
304 	vim = calloc(1, sizeof (*vim));
305 	if (vim == NULL)
306 		return (NULL);
307 
308 	vim->vim_dn = calloc(1, sizeof (*vim->vim_dn));
309 	if (vim->vim_dn == NULL) {
310 		free(vim);
311 		return (NULL);
312 	}
313 
314 	rc = objset_get_dnode(spa, os, mapping_object, vim->vim_dn);
315 	if (rc != 0) {
316 		free(vim->vim_dn);
317 		free(vim);
318 		return (NULL);
319 	}
320 
321 	vim->vim_spa = spa;
322 	vim->vim_phys = malloc(sizeof (*vim->vim_phys));
323 	if (vim->vim_phys == NULL) {
324 		free(vim->vim_dn);
325 		free(vim);
326 		return (NULL);
327 	}
328 
329 	vim_phys = (vdev_indirect_mapping_phys_t *)DN_BONUS(vim->vim_dn);
330 	*vim->vim_phys = *vim_phys;
331 
332 	vim->vim_objset = os;
333 	vim->vim_object = mapping_object;
334 	vim->vim_entries = NULL;
335 
336 	vim->vim_havecounts =
337 	    (vim->vim_dn->dn_bonuslen > VDEV_INDIRECT_MAPPING_SIZE_V0);
338 
339 	return (vim);
340 }
341 
342 /*
343  * Compare an offset with an indirect mapping entry; there are three
344  * possible scenarios:
345  *
346  *     1. The offset is "less than" the mapping entry; meaning the
347  *        offset is less than the source offset of the mapping entry. In
348  *        this case, there is no overlap between the offset and the
349  *        mapping entry and -1 will be returned.
350  *
351  *     2. The offset is "greater than" the mapping entry; meaning the
352  *        offset is greater than the mapping entry's source offset plus
353  *        the entry's size. In this case, there is no overlap between
354  *        the offset and the mapping entry and 1 will be returned.
355  *
356  *        NOTE: If the offset is actually equal to the entry's offset
357  *        plus size, this is considered to be "greater" than the entry,
358  *        and this case applies (i.e. 1 will be returned). Thus, the
359  *        entry's "range" can be considered to be inclusive at its
360  *        start, but exclusive at its end: e.g. [src, src + size).
361  *
362  *     3. The last case to consider is if the offset actually falls
363  *        within the mapping entry's range. If this is the case, the
364  *        offset is considered to be "equal to" the mapping entry and
365  *        0 will be returned.
366  *
367  *        NOTE: If the offset is equal to the entry's source offset,
368  *        this case applies and 0 will be returned. If the offset is
369  *        equal to the entry's source plus its size, this case does
370  *        *not* apply (see "NOTE" above for scenario 2), and 1 will be
371  *        returned.
372  */
373 static int
374 dva_mapping_overlap_compare(const void *v_key, const void *v_array_elem)
375 {
376 	const uint64_t *key = v_key;
377 	const vdev_indirect_mapping_entry_phys_t *array_elem =
378 	    v_array_elem;
379 	uint64_t src_offset = DVA_MAPPING_GET_SRC_OFFSET(array_elem);
380 
381 	if (*key < src_offset) {
382 		return (-1);
383 	} else if (*key < src_offset + DVA_GET_ASIZE(&array_elem->vimep_dst)) {
384 		return (0);
385 	} else {
386 		return (1);
387 	}
388 }
389 
390 /*
391  * Return array entry.
392  */
393 static vdev_indirect_mapping_entry_phys_t *
394 vdev_indirect_mapping_entry(vdev_indirect_mapping_t *vim, uint64_t index)
395 {
396 	uint64_t size;
397 	off_t offset = 0;
398 	int rc;
399 
400 	if (vim->vim_phys->vimp_num_entries == 0)
401 		return (NULL);
402 
403 	if (vim->vim_entries == NULL) {
404 		uint64_t bsize;
405 
406 		bsize = vim->vim_dn->dn_datablkszsec << SPA_MINBLOCKSHIFT;
407 		size = vim->vim_phys->vimp_num_entries *
408 		    sizeof (*vim->vim_entries);
409 		if (size > bsize) {
410 			size = bsize / sizeof (*vim->vim_entries);
411 			size *= sizeof (*vim->vim_entries);
412 		}
413 		vim->vim_entries = malloc(size);
414 		if (vim->vim_entries == NULL)
415 			return (NULL);
416 		vim->vim_num_entries = size / sizeof (*vim->vim_entries);
417 		offset = index * sizeof (*vim->vim_entries);
418 	}
419 
420 	/* We have data in vim_entries */
421 	if (offset == 0) {
422 		if (index >= vim->vim_entry_offset &&
423 		    index <= vim->vim_entry_offset + vim->vim_num_entries) {
424 			index -= vim->vim_entry_offset;
425 			return (&vim->vim_entries[index]);
426 		}
427 		offset = index * sizeof (*vim->vim_entries);
428 	}
429 
430 	vim->vim_entry_offset = index;
431 	size = vim->vim_num_entries * sizeof (*vim->vim_entries);
432 	rc = dnode_read(vim->vim_spa, vim->vim_dn, offset, vim->vim_entries,
433 	    size);
434 	if (rc != 0) {
435 		/* Read error, invalidate vim_entries. */
436 		free(vim->vim_entries);
437 		vim->vim_entries = NULL;
438 		return (NULL);
439 	}
440 	index -= vim->vim_entry_offset;
441 	return (&vim->vim_entries[index]);
442 }
443 
444 /*
445  * Returns the mapping entry for the given offset.
446  *
447  * It's possible that the given offset will not be in the mapping table
448  * (i.e. no mapping entries contain this offset), in which case, the
449  * return value depends on the "next_if_missing" parameter.
450  *
451  * If the offset is not found in the table and "next_if_missing" is
452  * B_FALSE, then NULL will always be returned. The behavior is intended
453  * to allow consumers to get the entry corresponding to the offset
454  * parameter, iff the offset overlaps with an entry in the table.
455  *
456  * If the offset is not found in the table and "next_if_missing" is
457  * B_TRUE, then the entry nearest to the given offset will be returned,
458  * such that the entry's source offset is greater than the offset
459  * passed in (i.e. the "next" mapping entry in the table is returned, if
460  * the offset is missing from the table). If there are no entries whose
461  * source offset is greater than the passed in offset, NULL is returned.
462  */
463 static vdev_indirect_mapping_entry_phys_t *
464 vdev_indirect_mapping_entry_for_offset(vdev_indirect_mapping_t *vim,
465     uint64_t offset)
466 {
467 	ASSERT(vim->vim_phys->vimp_num_entries > 0);
468 
469 	vdev_indirect_mapping_entry_phys_t *entry;
470 
471 	uint64_t last = vim->vim_phys->vimp_num_entries - 1;
472 	uint64_t base = 0;
473 
474 	/*
475 	 * We don't define these inside of the while loop because we use
476 	 * their value in the case that offset isn't in the mapping.
477 	 */
478 	uint64_t mid;
479 	int result;
480 
481 	while (last >= base) {
482 		mid = base + ((last - base) >> 1);
483 
484 		entry = vdev_indirect_mapping_entry(vim, mid);
485 		if (entry == NULL)
486 			break;
487 		result = dva_mapping_overlap_compare(&offset, entry);
488 
489 		if (result == 0) {
490 			break;
491 		} else if (result < 0) {
492 			last = mid - 1;
493 		} else {
494 			base = mid + 1;
495 		}
496 	}
497 	return (entry);
498 }
499 
500 /*
501  * Given an indirect vdev and an extent on that vdev, it duplicates the
502  * physical entries of the indirect mapping that correspond to the extent
503  * to a new array and returns a pointer to it. In addition, copied_entries
504  * is populated with the number of mapping entries that were duplicated.
505  *
506  * Finally, since we are doing an allocation, it is up to the caller to
507  * free the array allocated in this function.
508  */
509 vdev_indirect_mapping_entry_phys_t *
510 vdev_indirect_mapping_duplicate_adjacent_entries(vdev_t *vd, uint64_t offset,
511     uint64_t asize, uint64_t *copied_entries)
512 {
513 	vdev_indirect_mapping_entry_phys_t *duplicate_mappings = NULL;
514 	vdev_indirect_mapping_t *vim = vd->v_mapping;
515 	uint64_t entries = 0;
516 
517 	vdev_indirect_mapping_entry_phys_t *first_mapping =
518 	    vdev_indirect_mapping_entry_for_offset(vim, offset);
519 	ASSERT3P(first_mapping, !=, NULL);
520 
521 	vdev_indirect_mapping_entry_phys_t *m = first_mapping;
522 	while (asize > 0) {
523 		uint64_t size = DVA_GET_ASIZE(&m->vimep_dst);
524 		uint64_t inner_offset = offset - DVA_MAPPING_GET_SRC_OFFSET(m);
525 		uint64_t inner_size = MIN(asize, size - inner_offset);
526 
527 		offset += inner_size;
528 		asize -= inner_size;
529 		entries++;
530 		m++;
531 	}
532 
533 	size_t copy_length = entries * sizeof (*first_mapping);
534 	duplicate_mappings = malloc(copy_length);
535 	if (duplicate_mappings != NULL)
536 		bcopy(first_mapping, duplicate_mappings, copy_length);
537 	else
538 		entries = 0;
539 
540 	*copied_entries = entries;
541 
542 	return (duplicate_mappings);
543 }
544 
545 static vdev_t *
546 vdev_lookup_top(spa_t *spa, uint64_t vdev)
547 {
548 	vdev_t *rvd;
549 	vdev_list_t *vlist;
550 
551 	vlist = &spa->spa_root_vdev->v_children;
552 	STAILQ_FOREACH(rvd, vlist, v_childlink)
553 		if (rvd->v_id == vdev)
554 			break;
555 
556 	return (rvd);
557 }
558 
559 /*
560  * This is a callback for vdev_indirect_remap() which allocates an
561  * indirect_split_t for each split segment and adds it to iv_splits.
562  */
563 static void
564 vdev_indirect_gather_splits(uint64_t split_offset, vdev_t *vd, uint64_t offset,
565     uint64_t size, void *arg)
566 {
567 	int n = 1;
568 	zio_t *zio = arg;
569 	indirect_vsd_t *iv = zio->io_vsd;
570 
571 	if (vd->v_read == vdev_indirect_read)
572 		return;
573 
574 	if (vd->v_read == vdev_mirror_read)
575 		n = vd->v_nchildren;
576 
577 	indirect_split_t *is =
578 	    malloc(offsetof(indirect_split_t, is_child[n]));
579 	if (is == NULL) {
580 		zio->io_error = ENOMEM;
581 		return;
582 	}
583 	bzero(is, offsetof(indirect_split_t, is_child[n]));
584 
585 	is->is_children = n;
586 	is->is_size = size;
587 	is->is_split_offset = split_offset;
588 	is->is_target_offset = offset;
589 	is->is_vdev = vd;
590 
591 	/*
592 	 * Note that we only consider multiple copies of the data for
593 	 * *mirror* vdevs.  We don't for "replacing" or "spare" vdevs, even
594 	 * though they use the same ops as mirror, because there's only one
595 	 * "good" copy under the replacing/spare.
596 	 */
597 	if (vd->v_read == vdev_mirror_read) {
598 		int i = 0;
599 		vdev_t *kid;
600 
601 		STAILQ_FOREACH(kid, &vd->v_children, v_childlink) {
602 			is->is_child[i++].ic_vdev = kid;
603 		}
604 	} else {
605 		is->is_child[0].ic_vdev = vd;
606 	}
607 
608 	list_insert_tail(&iv->iv_splits, is);
609 }
610 
611 static void
612 vdev_indirect_remap(vdev_t *vd, uint64_t offset, uint64_t asize, void *arg)
613 {
614 	list_t stack;
615 	spa_t *spa = vd->v_spa;
616 	zio_t *zio = arg;
617 	remap_segment_t *rs;
618 
619 	list_create(&stack, sizeof (remap_segment_t),
620 	    offsetof(remap_segment_t, rs_node));
621 
622 	rs = rs_alloc(vd, offset, asize, 0);
623 	if (rs == NULL) {
624 		printf("vdev_indirect_remap: out of memory.\n");
625 		zio->io_error = ENOMEM;
626 	}
627 	for (; rs != NULL; rs = list_remove_head(&stack)) {
628 		vdev_t *v = rs->rs_vd;
629 		uint64_t num_entries = 0;
630 		/* vdev_indirect_mapping_t *vim = v->v_mapping; */
631 		vdev_indirect_mapping_entry_phys_t *mapping =
632 		    vdev_indirect_mapping_duplicate_adjacent_entries(v,
633 		    rs->rs_offset, rs->rs_asize, &num_entries);
634 
635 		if (num_entries == 0)
636 			zio->io_error = ENOMEM;
637 
638 		for (uint64_t i = 0; i < num_entries; i++) {
639 			vdev_indirect_mapping_entry_phys_t *m = &mapping[i];
640 			uint64_t size = DVA_GET_ASIZE(&m->vimep_dst);
641 			uint64_t dst_offset = DVA_GET_OFFSET(&m->vimep_dst);
642 			uint64_t dst_vdev = DVA_GET_VDEV(&m->vimep_dst);
643 			uint64_t inner_offset = rs->rs_offset -
644 			    DVA_MAPPING_GET_SRC_OFFSET(m);
645 			uint64_t inner_size =
646 			    MIN(rs->rs_asize, size - inner_offset);
647 			vdev_t *dst_v = vdev_lookup_top(spa, dst_vdev);
648 
649 			if (dst_v->v_read == vdev_indirect_read) {
650 				remap_segment_t *o;
651 
652 				o = rs_alloc(dst_v, dst_offset + inner_offset,
653 				    inner_size, rs->rs_split_offset);
654 				if (o == NULL) {
655 					printf("vdev_indirect_remap: "
656 					    "out of memory.\n");
657 					zio->io_error = ENOMEM;
658 					break;
659 				}
660 
661 				list_insert_head(&stack, o);
662 			}
663 			vdev_indirect_gather_splits(rs->rs_split_offset, dst_v,
664 			    dst_offset + inner_offset,
665 			    inner_size, arg);
666 
667 			/*
668 			 * vdev_indirect_gather_splits can have memory
669 			 * allocation error, we can not recover from it.
670 			 */
671 			if (zio->io_error != 0)
672 				break;
673 			rs->rs_offset += inner_size;
674 			rs->rs_asize -= inner_size;
675 			rs->rs_split_offset += inner_size;
676 		}
677 
678 		free(mapping);
679 		free(rs);
680 		if (zio->io_error != 0)
681 			break;
682 	}
683 
684 	list_destroy(&stack);
685 }
686 
687 static void
688 vdev_indirect_map_free(zio_t *zio)
689 {
690 	indirect_vsd_t *iv = zio->io_vsd;
691 	indirect_split_t *is;
692 
693 	while ((is = list_head(&iv->iv_splits)) != NULL) {
694 		for (int c = 0; c < is->is_children; c++) {
695 			indirect_child_t *ic = &is->is_child[c];
696 			free(ic->ic_data);
697 		}
698 		list_remove(&iv->iv_splits, is);
699 		free(is);
700 	}
701 	free(iv);
702 }
703 
704 static int
705 vdev_indirect_read(vdev_t *vdev, const blkptr_t *bp, void *buf,
706     off_t offset, size_t bytes)
707 {
708 	zio_t zio;
709 	spa_t *spa = vdev->v_spa;
710 	indirect_vsd_t *iv;
711 	indirect_split_t *first;
712 	int rc = EIO;
713 
714 	iv = calloc(1, sizeof(*iv));
715 	if (iv == NULL)
716 		return (ENOMEM);
717 
718 	list_create(&iv->iv_splits,
719 	    sizeof (indirect_split_t), offsetof(indirect_split_t, is_node));
720 
721 	bzero(&zio, sizeof(zio));
722 	zio.io_spa = spa;
723 	zio.io_bp = (blkptr_t *)bp;
724 	zio.io_data = buf;
725 	zio.io_size = bytes;
726 	zio.io_offset = offset;
727 	zio.io_vd = vdev;
728 	zio.io_vsd = iv;
729 
730 	if (vdev->v_mapping == NULL) {
731 		vdev_indirect_config_t *vic;
732 
733 		vic = &vdev->vdev_indirect_config;
734 		vdev->v_mapping = vdev_indirect_mapping_open(spa,
735 		    spa->spa_mos, vic->vic_mapping_object);
736 	}
737 
738 	vdev_indirect_remap(vdev, offset, bytes, &zio);
739 	if (zio.io_error != 0)
740 		return (zio.io_error);
741 
742 	first = list_head(&iv->iv_splits);
743 	if (first->is_size == zio.io_size) {
744 		/*
745 		 * This is not a split block; we are pointing to the entire
746 		 * data, which will checksum the same as the original data.
747 		 * Pass the BP down so that the child i/o can verify the
748 		 * checksum, and try a different location if available
749 		 * (e.g. on a mirror).
750 		 *
751 		 * While this special case could be handled the same as the
752 		 * general (split block) case, doing it this way ensures
753 		 * that the vast majority of blocks on indirect vdevs
754 		 * (which are not split) are handled identically to blocks
755 		 * on non-indirect vdevs.  This allows us to be less strict
756 		 * about performance in the general (but rare) case.
757 		 */
758 		rc = first->is_vdev->v_read(first->is_vdev, zio.io_bp,
759 		    zio.io_data, first->is_target_offset, bytes);
760 	} else {
761 		iv->iv_split_block = B_TRUE;
762 		/*
763 		 * Read one copy of each split segment, from the
764 		 * top-level vdev.  Since we don't know the
765 		 * checksum of each split individually, the child
766 		 * zio can't ensure that we get the right data.
767 		 * E.g. if it's a mirror, it will just read from a
768 		 * random (healthy) leaf vdev.  We have to verify
769 		 * the checksum in vdev_indirect_io_done().
770 		 */
771 		for (indirect_split_t *is = list_head(&iv->iv_splits);
772 		    is != NULL; is = list_next(&iv->iv_splits, is)) {
773 			char *ptr = zio.io_data;
774 
775 			rc = is->is_vdev->v_read(is->is_vdev, zio.io_bp,
776 			    ptr + is->is_split_offset, is->is_target_offset,
777 			    is->is_size);
778 		}
779 		if (zio_checksum_verify(spa, zio.io_bp, zio.io_data))
780 			rc = ECKSUM;
781 		else
782 			rc = 0;
783 	}
784 
785 	vdev_indirect_map_free(&zio);
786 	if (rc == 0)
787 		rc = zio.io_error;
788 
789 	return (rc);
790 }
791 
792 static int
793 vdev_disk_read(vdev_t *vdev, const blkptr_t *bp, void *buf,
794     off_t offset, size_t bytes)
795 {
796 
797 	return (vdev_read_phys(vdev, bp, buf,
798 	    offset + VDEV_LABEL_START_SIZE, bytes));
799 }
800 
801 static int
802 vdev_missing_read(vdev_t *vdev __unused, const blkptr_t *bp __unused,
803     void *buf __unused, off_t offset __unused, size_t bytes __unused)
804 {
805 
806 	return (ENOTSUP);
807 }
808 
809 static int
810 vdev_mirror_read(vdev_t *vdev, const blkptr_t *bp, void *buf,
811     off_t offset, size_t bytes)
812 {
813 	vdev_t *kid;
814 	int rc;
815 
816 	rc = EIO;
817 	STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) {
818 		if (kid->v_state != VDEV_STATE_HEALTHY)
819 			continue;
820 		rc = kid->v_read(kid, bp, buf, offset, bytes);
821 		if (!rc)
822 			return (0);
823 	}
824 
825 	return (rc);
826 }
827 
828 static int
829 vdev_replacing_read(vdev_t *vdev, const blkptr_t *bp, void *buf,
830     off_t offset, size_t bytes)
831 {
832 	vdev_t *kid;
833 
834 	/*
835 	 * Here we should have two kids:
836 	 * First one which is the one we are replacing and we can trust
837 	 * only this one to have valid data, but it might not be present.
838 	 * Second one is that one we are replacing with. It is most likely
839 	 * healthy, but we can't trust it has needed data, so we won't use it.
840 	 */
841 	kid = STAILQ_FIRST(&vdev->v_children);
842 	if (kid == NULL)
843 		return (EIO);
844 	if (kid->v_state != VDEV_STATE_HEALTHY)
845 		return (EIO);
846 	return (kid->v_read(kid, bp, buf, offset, bytes));
847 }
848 
849 static vdev_t *
850 vdev_find(uint64_t guid)
851 {
852 	vdev_t *vdev;
853 
854 	STAILQ_FOREACH(vdev, &zfs_vdevs, v_alllink)
855 		if (vdev->v_guid == guid)
856 			return (vdev);
857 
858 	return (0);
859 }
860 
861 static vdev_t *
862 vdev_create(uint64_t guid, vdev_read_t *_read)
863 {
864 	vdev_t *vdev;
865 	vdev_indirect_config_t *vic;
866 
867 	vdev = calloc(1, sizeof(vdev_t));
868 	if (vdev != NULL) {
869 		STAILQ_INIT(&vdev->v_children);
870 		vdev->v_guid = guid;
871 		vdev->v_read = _read;
872 
873 		/*
874 		 * root vdev has no read function, we use this fact to
875 		 * skip setting up data we do not need for root vdev.
876 		 * We only point root vdev from spa.
877 		 */
878 		if (_read != NULL) {
879 			vic = &vdev->vdev_indirect_config;
880 			vic->vic_prev_indirect_vdev = UINT64_MAX;
881 			STAILQ_INSERT_TAIL(&zfs_vdevs, vdev, v_alllink);
882 		}
883 	}
884 
885 	return (vdev);
886 }
887 
888 static void
889 vdev_set_initial_state(vdev_t *vdev, const nvlist_t *nvlist)
890 {
891 	uint64_t is_offline, is_faulted, is_degraded, is_removed, isnt_present;
892 	uint64_t is_log;
893 
894 	is_offline = is_removed = is_faulted = is_degraded = isnt_present = 0;
895 	is_log = 0;
896 	(void) nvlist_find(nvlist, ZPOOL_CONFIG_OFFLINE, DATA_TYPE_UINT64, NULL,
897 	    &is_offline, NULL);
898 	(void) nvlist_find(nvlist, ZPOOL_CONFIG_REMOVED, DATA_TYPE_UINT64, NULL,
899 	    &is_removed, NULL);
900 	(void) nvlist_find(nvlist, ZPOOL_CONFIG_FAULTED, DATA_TYPE_UINT64, NULL,
901 	    &is_faulted, NULL);
902 	(void) nvlist_find(nvlist, ZPOOL_CONFIG_DEGRADED, DATA_TYPE_UINT64,
903 	    NULL, &is_degraded, NULL);
904 	(void) nvlist_find(nvlist, ZPOOL_CONFIG_NOT_PRESENT, DATA_TYPE_UINT64,
905 	    NULL, &isnt_present, NULL);
906 	(void) nvlist_find(nvlist, ZPOOL_CONFIG_IS_LOG, DATA_TYPE_UINT64, NULL,
907 	    &is_log, NULL);
908 
909 	if (is_offline != 0)
910 		vdev->v_state = VDEV_STATE_OFFLINE;
911 	else if (is_removed != 0)
912 		vdev->v_state = VDEV_STATE_REMOVED;
913 	else if (is_faulted != 0)
914 		vdev->v_state = VDEV_STATE_FAULTED;
915 	else if (is_degraded != 0)
916 		vdev->v_state = VDEV_STATE_DEGRADED;
917 	else if (isnt_present != 0)
918 		vdev->v_state = VDEV_STATE_CANT_OPEN;
919 
920 	vdev->v_islog = is_log != 0;
921 }
922 
923 static int
924 vdev_init(uint64_t guid, const nvlist_t *nvlist, vdev_t **vdevp)
925 {
926 	uint64_t id, ashift, asize, nparity;
927 	const char *path;
928 	const char *type;
929 	int len, pathlen;
930 	char *name;
931 	vdev_t *vdev;
932 
933 	if (nvlist_find(nvlist, ZPOOL_CONFIG_ID, DATA_TYPE_UINT64, NULL, &id,
934 	    NULL) ||
935 	    nvlist_find(nvlist, ZPOOL_CONFIG_TYPE, DATA_TYPE_STRING, NULL,
936 	    &type, &len)) {
937 		return (ENOENT);
938 	}
939 
940 	if (memcmp(type, VDEV_TYPE_MIRROR, len) != 0 &&
941 	    memcmp(type, VDEV_TYPE_DISK, len) != 0 &&
942 #ifdef ZFS_TEST
943 	    memcmp(type, VDEV_TYPE_FILE, len) != 0 &&
944 #endif
945 	    memcmp(type, VDEV_TYPE_RAIDZ, len) != 0 &&
946 	    memcmp(type, VDEV_TYPE_INDIRECT, len) != 0 &&
947 	    memcmp(type, VDEV_TYPE_REPLACING, len) != 0 &&
948 	    memcmp(type, VDEV_TYPE_HOLE, len) != 0) {
949 		printf("ZFS: can only boot from disk, mirror, raidz1, "
950 		    "raidz2 and raidz3 vdevs, got: %.*s\n", len, type);
951 		return (EIO);
952 	}
953 
954 	if (memcmp(type, VDEV_TYPE_MIRROR, len) == 0)
955 		vdev = vdev_create(guid, vdev_mirror_read);
956 	else if (memcmp(type, VDEV_TYPE_RAIDZ, len) == 0)
957 		vdev = vdev_create(guid, vdev_raidz_read);
958 	else if (memcmp(type, VDEV_TYPE_REPLACING, len) == 0)
959 		vdev = vdev_create(guid, vdev_replacing_read);
960 	else if (memcmp(type, VDEV_TYPE_INDIRECT, len) == 0) {
961 		vdev_indirect_config_t *vic;
962 
963 		vdev = vdev_create(guid, vdev_indirect_read);
964 		if (vdev != NULL) {
965 			vdev->v_state = VDEV_STATE_HEALTHY;
966 			vic = &vdev->vdev_indirect_config;
967 
968 			nvlist_find(nvlist,
969 			    ZPOOL_CONFIG_INDIRECT_OBJECT,
970 			    DATA_TYPE_UINT64,
971 			    NULL, &vic->vic_mapping_object, NULL);
972 			nvlist_find(nvlist,
973 			    ZPOOL_CONFIG_INDIRECT_BIRTHS,
974 			    DATA_TYPE_UINT64,
975 			    NULL, &vic->vic_births_object, NULL);
976 			nvlist_find(nvlist,
977 			    ZPOOL_CONFIG_PREV_INDIRECT_VDEV,
978 			    DATA_TYPE_UINT64,
979 			    NULL, &vic->vic_prev_indirect_vdev, NULL);
980 		}
981 	} else if (memcmp(type, VDEV_TYPE_HOLE, len) == 0) {
982 		vdev = vdev_create(guid, vdev_missing_read);
983 	} else {
984 		vdev = vdev_create(guid, vdev_disk_read);
985 	}
986 
987 	if (vdev == NULL)
988 		return (ENOMEM);
989 
990 	vdev_set_initial_state(vdev, nvlist);
991 	vdev->v_id = id;
992 	if (nvlist_find(nvlist, ZPOOL_CONFIG_ASHIFT,
993 	    DATA_TYPE_UINT64, NULL, &ashift, NULL) == 0)
994 		vdev->v_ashift = ashift;
995 
996 	if (nvlist_find(nvlist, ZPOOL_CONFIG_ASIZE,
997 	    DATA_TYPE_UINT64, NULL, &asize, NULL) == 0) {
998 		vdev->v_psize = asize +
999 		    VDEV_LABEL_START_SIZE + VDEV_LABEL_END_SIZE;
1000 	}
1001 
1002 	if (nvlist_find(nvlist, ZPOOL_CONFIG_NPARITY,
1003 	    DATA_TYPE_UINT64, NULL, &nparity, NULL) == 0)
1004 		vdev->v_nparity = nparity;
1005 
1006 	if (nvlist_find(nvlist, ZPOOL_CONFIG_PATH,
1007 	    DATA_TYPE_STRING, NULL, &path, &pathlen) == 0) {
1008 		char prefix[] = "/dev/";
1009 
1010 		len = strlen(prefix);
1011 		if (len < pathlen && memcmp(path, prefix, len) == 0) {
1012 			path += len;
1013 			pathlen -= len;
1014 		}
1015 		name = malloc(pathlen + 1);
1016 		bcopy(path, name, pathlen);
1017 		name[pathlen] = '\0';
1018 		vdev->v_name = name;
1019 	} else {
1020 		name = NULL;
1021 		if (memcmp(type, VDEV_TYPE_RAIDZ, len) == 0) {
1022 			if (vdev->v_nparity < 1 ||
1023 			    vdev->v_nparity > 3) {
1024 				printf("ZFS: invalid raidz parity: %d\n",
1025 				    vdev->v_nparity);
1026 				return (EIO);
1027 			}
1028 			(void) asprintf(&name, "%.*s%d-%" PRIu64, len, type,
1029 			    vdev->v_nparity, id);
1030 		} else {
1031 			(void) asprintf(&name, "%.*s-%" PRIu64, len, type, id);
1032 		}
1033 		vdev->v_name = name;
1034 	}
1035 	*vdevp = vdev;
1036 	return (0);
1037 }
1038 
1039 /*
1040  * Find slot for vdev. We return either NULL to signal to use
1041  * STAILQ_INSERT_HEAD, or we return link element to be used with
1042  * STAILQ_INSERT_AFTER.
1043  */
1044 static vdev_t *
1045 vdev_find_previous(vdev_t *top_vdev, vdev_t *vdev)
1046 {
1047 	vdev_t *v, *previous;
1048 
1049 	if (STAILQ_EMPTY(&top_vdev->v_children))
1050 		return (NULL);
1051 
1052 	previous = NULL;
1053 	STAILQ_FOREACH(v, &top_vdev->v_children, v_childlink) {
1054 		if (v->v_id > vdev->v_id)
1055 			return (previous);
1056 
1057 		if (v->v_id == vdev->v_id)
1058 			return (v);
1059 
1060 		if (v->v_id < vdev->v_id)
1061 			previous = v;
1062 	}
1063 	return (previous);
1064 }
1065 
1066 static size_t
1067 vdev_child_count(vdev_t *vdev)
1068 {
1069 	vdev_t *v;
1070 	size_t count;
1071 
1072 	count = 0;
1073 	STAILQ_FOREACH(v, &vdev->v_children, v_childlink) {
1074 		count++;
1075 	}
1076 	return (count);
1077 }
1078 
1079 /*
1080  * Insert vdev into top_vdev children list. List is ordered by v_id.
1081  */
1082 static void
1083 vdev_insert(vdev_t *top_vdev, vdev_t *vdev)
1084 {
1085 	vdev_t *previous;
1086 	size_t count;
1087 
1088 	/*
1089 	 * The top level vdev can appear in random order, depending how
1090 	 * the firmware is presenting the disk devices.
1091 	 * However, we will insert vdev to create list ordered by v_id,
1092 	 * so we can use either STAILQ_INSERT_HEAD or STAILQ_INSERT_AFTER
1093 	 * as STAILQ does not have insert before.
1094 	 */
1095 	previous = vdev_find_previous(top_vdev, vdev);
1096 
1097 	if (previous == NULL) {
1098 		STAILQ_INSERT_HEAD(&top_vdev->v_children, vdev, v_childlink);
1099 	} else if (previous->v_id == vdev->v_id) {
1100 		/*
1101 		 * This vdev was configured from label config,
1102 		 * do not insert duplicate.
1103 		 */
1104 		return;
1105 	} else {
1106 		STAILQ_INSERT_AFTER(&top_vdev->v_children, previous, vdev,
1107 		    v_childlink);
1108 	}
1109 
1110 	count = vdev_child_count(top_vdev);
1111 	if (top_vdev->v_nchildren < count)
1112 		top_vdev->v_nchildren = count;
1113 }
1114 
1115 static int
1116 vdev_from_nvlist(spa_t *spa, uint64_t top_guid, const nvlist_t *nvlist)
1117 {
1118 	vdev_t *top_vdev, *vdev;
1119 	nvlist_t **kids = NULL;
1120 	int rc, nkids;
1121 
1122 	/* Get top vdev. */
1123 	top_vdev = vdev_find(top_guid);
1124 	if (top_vdev == NULL) {
1125 		rc = vdev_init(top_guid, nvlist, &top_vdev);
1126 		if (rc != 0)
1127 			return (rc);
1128 		top_vdev->v_spa = spa;
1129 		top_vdev->v_top = top_vdev;
1130 		vdev_insert(spa->spa_root_vdev, top_vdev);
1131 	}
1132 
1133 	/* Add children if there are any. */
1134 	rc = nvlist_find(nvlist, ZPOOL_CONFIG_CHILDREN, DATA_TYPE_NVLIST_ARRAY,
1135 	    &nkids, &kids, NULL);
1136 	if (rc == 0) {
1137 		for (int i = 0; i < nkids; i++) {
1138 			uint64_t guid;
1139 
1140 			rc = nvlist_find(kids[i], ZPOOL_CONFIG_GUID,
1141 			    DATA_TYPE_UINT64, NULL, &guid, NULL);
1142 			if (rc != 0)
1143 				goto done;
1144 
1145 			rc = vdev_init(guid, kids[i], &vdev);
1146 			if (rc != 0)
1147 				goto done;
1148 
1149 			vdev->v_spa = spa;
1150 			vdev->v_top = top_vdev;
1151 			vdev_insert(top_vdev, vdev);
1152 		}
1153 	} else {
1154 		/*
1155 		 * When there are no children, nvlist_find() does return
1156 		 * error, reset it because leaf devices have no children.
1157 		 */
1158 		rc = 0;
1159 	}
1160 done:
1161 	if (kids != NULL) {
1162 		for (int i = 0; i < nkids; i++)
1163 			nvlist_destroy(kids[i]);
1164 		free(kids);
1165 	}
1166 
1167 	return (rc);
1168 }
1169 
1170 static int
1171 vdev_init_from_label(spa_t *spa, const nvlist_t *nvlist)
1172 {
1173 	uint64_t pool_guid, top_guid;
1174 	nvlist_t *vdevs;
1175 	int rc;
1176 
1177 	if (nvlist_find(nvlist, ZPOOL_CONFIG_POOL_GUID, DATA_TYPE_UINT64,
1178 	    NULL, &pool_guid, NULL) ||
1179 	    nvlist_find(nvlist, ZPOOL_CONFIG_TOP_GUID, DATA_TYPE_UINT64,
1180 	    NULL, &top_guid, NULL) ||
1181 	    nvlist_find(nvlist, ZPOOL_CONFIG_VDEV_TREE, DATA_TYPE_NVLIST,
1182 	    NULL, &vdevs, NULL)) {
1183 		printf("ZFS: can't find vdev details\n");
1184 		return (ENOENT);
1185 	}
1186 
1187 	rc = vdev_from_nvlist(spa, top_guid, vdevs);
1188 	nvlist_destroy(vdevs);
1189 	return (rc);
1190 }
1191 
1192 static void
1193 vdev_set_state(vdev_t *vdev)
1194 {
1195 	vdev_t *kid;
1196 	int good_kids;
1197 	int bad_kids;
1198 
1199 	STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) {
1200 		vdev_set_state(kid);
1201 	}
1202 
1203 	/*
1204 	 * A mirror or raidz is healthy if all its kids are healthy. A
1205 	 * mirror is degraded if any of its kids is healthy; a raidz
1206 	 * is degraded if at most nparity kids are offline.
1207 	 */
1208 	if (STAILQ_FIRST(&vdev->v_children)) {
1209 		good_kids = 0;
1210 		bad_kids = 0;
1211 		STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) {
1212 			if (kid->v_state == VDEV_STATE_HEALTHY)
1213 				good_kids++;
1214 			else
1215 				bad_kids++;
1216 		}
1217 		if (bad_kids == 0) {
1218 			vdev->v_state = VDEV_STATE_HEALTHY;
1219 		} else {
1220 			if (vdev->v_read == vdev_mirror_read) {
1221 				if (good_kids) {
1222 					vdev->v_state = VDEV_STATE_DEGRADED;
1223 				} else {
1224 					vdev->v_state = VDEV_STATE_OFFLINE;
1225 				}
1226 			} else if (vdev->v_read == vdev_raidz_read) {
1227 				if (bad_kids > vdev->v_nparity) {
1228 					vdev->v_state = VDEV_STATE_OFFLINE;
1229 				} else {
1230 					vdev->v_state = VDEV_STATE_DEGRADED;
1231 				}
1232 			}
1233 		}
1234 	}
1235 }
1236 
1237 static int
1238 vdev_update_from_nvlist(uint64_t top_guid, const nvlist_t *nvlist)
1239 {
1240 	vdev_t *vdev;
1241 	nvlist_t **kids = NULL;
1242 	int rc, nkids;
1243 
1244 	/* Update top vdev. */
1245 	vdev = vdev_find(top_guid);
1246 	if (vdev != NULL)
1247 		vdev_set_initial_state(vdev, nvlist);
1248 
1249 	/* Update children if there are any. */
1250 	rc = nvlist_find(nvlist, ZPOOL_CONFIG_CHILDREN, DATA_TYPE_NVLIST_ARRAY,
1251 	    &nkids, &kids, NULL);
1252 	if (rc == 0) {
1253 		for (int i = 0; i < nkids; i++) {
1254 			uint64_t guid;
1255 
1256 			rc = nvlist_find(kids[i], ZPOOL_CONFIG_GUID,
1257 			    DATA_TYPE_UINT64, NULL, &guid, NULL);
1258 			if (rc != 0)
1259 				break;
1260 
1261 			vdev = vdev_find(guid);
1262 			if (vdev != NULL)
1263 				vdev_set_initial_state(vdev, kids[i]);
1264 		}
1265 	} else {
1266 		rc = 0;
1267 	}
1268 	if (kids != NULL) {
1269 		for (int i = 0; i < nkids; i++)
1270 			nvlist_destroy(kids[i]);
1271 		free(kids);
1272 	}
1273 
1274 	return (rc);
1275 }
1276 
1277 static int
1278 vdev_init_from_nvlist(spa_t *spa, const nvlist_t *nvlist)
1279 {
1280 	uint64_t pool_guid, vdev_children;
1281 	nvlist_t *vdevs = NULL, **kids = NULL;
1282 	int rc, nkids;
1283 
1284 	if (nvlist_find(nvlist, ZPOOL_CONFIG_POOL_GUID, DATA_TYPE_UINT64,
1285 	    NULL, &pool_guid, NULL) ||
1286 	    nvlist_find(nvlist, ZPOOL_CONFIG_VDEV_CHILDREN, DATA_TYPE_UINT64,
1287 	    NULL, &vdev_children, NULL) ||
1288 	    nvlist_find(nvlist, ZPOOL_CONFIG_VDEV_TREE, DATA_TYPE_NVLIST,
1289 	    NULL, &vdevs, NULL)) {
1290 		printf("ZFS: can't find vdev details\n");
1291 		return (ENOENT);
1292 	}
1293 
1294 	/* Wrong guid?! */
1295 	if (spa->spa_guid != pool_guid) {
1296 		nvlist_destroy(vdevs);
1297 		return (EINVAL);
1298 	}
1299 
1300 	spa->spa_root_vdev->v_nchildren = vdev_children;
1301 
1302 	rc = nvlist_find(vdevs, ZPOOL_CONFIG_CHILDREN, DATA_TYPE_NVLIST_ARRAY,
1303 	    &nkids, &kids, NULL);
1304 	nvlist_destroy(vdevs);
1305 
1306 	/*
1307 	 * MOS config has at least one child for root vdev.
1308 	 */
1309 	if (rc != 0)
1310 		return (rc);
1311 
1312 	for (int i = 0; i < nkids; i++) {
1313 		uint64_t guid;
1314 		vdev_t *vdev;
1315 
1316 		rc = nvlist_find(kids[i], ZPOOL_CONFIG_GUID, DATA_TYPE_UINT64,
1317 		    NULL, &guid, NULL);
1318 		if (rc != 0)
1319 			break;
1320 		vdev = vdev_find(guid);
1321 		/*
1322 		 * Top level vdev is missing, create it.
1323 		 */
1324 		if (vdev == NULL)
1325 			rc = vdev_from_nvlist(spa, guid, kids[i]);
1326 		else
1327 			rc = vdev_update_from_nvlist(guid, kids[i]);
1328 		if (rc != 0)
1329 			break;
1330 	}
1331 	if (kids != NULL) {
1332 		for (int i = 0; i < nkids; i++)
1333 			nvlist_destroy(kids[i]);
1334 		free(kids);
1335 	}
1336 
1337 	/*
1338 	 * Re-evaluate top-level vdev state.
1339 	 */
1340 	vdev_set_state(spa->spa_root_vdev);
1341 
1342 	return (rc);
1343 }
1344 
1345 static spa_t *
1346 spa_find_by_guid(uint64_t guid)
1347 {
1348 	spa_t *spa;
1349 
1350 	STAILQ_FOREACH(spa, &zfs_pools, spa_link)
1351 		if (spa->spa_guid == guid)
1352 			return (spa);
1353 
1354 	return (NULL);
1355 }
1356 
1357 static spa_t *
1358 spa_find_by_name(const char *name)
1359 {
1360 	spa_t *spa;
1361 
1362 	STAILQ_FOREACH(spa, &zfs_pools, spa_link)
1363 		if (strcmp(spa->spa_name, name) == 0)
1364 			return (spa);
1365 
1366 	return (NULL);
1367 }
1368 
1369 static spa_t *
1370 spa_create(uint64_t guid, const char *name)
1371 {
1372 	spa_t *spa;
1373 
1374 	if ((spa = calloc(1, sizeof(spa_t))) == NULL)
1375 		return (NULL);
1376 	if ((spa->spa_name = strdup(name)) == NULL) {
1377 		free(spa);
1378 		return (NULL);
1379 	}
1380 	spa->spa_uberblock = &spa->spa_uberblock_master;
1381 	spa->spa_mos = &spa->spa_mos_master;
1382 	spa->spa_guid = guid;
1383 	spa->spa_root_vdev = vdev_create(guid, NULL);
1384 	if (spa->spa_root_vdev == NULL) {
1385 		free(spa->spa_name);
1386 		free(spa);
1387 		return (NULL);
1388 	}
1389 	spa->spa_root_vdev->v_name = strdup("root");
1390 	STAILQ_INSERT_TAIL(&zfs_pools, spa, spa_link);
1391 
1392 	return (spa);
1393 }
1394 
1395 static const char *
1396 state_name(vdev_state_t state)
1397 {
1398 	static const char *names[] = {
1399 		"UNKNOWN",
1400 		"CLOSED",
1401 		"OFFLINE",
1402 		"REMOVED",
1403 		"CANT_OPEN",
1404 		"FAULTED",
1405 		"DEGRADED",
1406 		"ONLINE"
1407 	};
1408 	return (names[state]);
1409 }
1410 
1411 #ifdef BOOT2
1412 
1413 #define pager_printf printf
1414 
1415 #else
1416 
1417 static int
1418 pager_printf(const char *fmt, ...)
1419 {
1420 	char line[80];
1421 	va_list args;
1422 
1423 	va_start(args, fmt);
1424 	vsnprintf(line, sizeof(line), fmt, args);
1425 	va_end(args);
1426 	return (pager_output(line));
1427 }
1428 
1429 #endif
1430 
1431 #define	STATUS_FORMAT	"        %s %s\n"
1432 
1433 static int
1434 print_state(int indent, const char *name, vdev_state_t state)
1435 {
1436 	int i;
1437 	char buf[512];
1438 
1439 	buf[0] = 0;
1440 	for (i = 0; i < indent; i++)
1441 		strcat(buf, "  ");
1442 	strcat(buf, name);
1443 	return (pager_printf(STATUS_FORMAT, buf, state_name(state)));
1444 }
1445 
1446 static int
1447 vdev_status(vdev_t *vdev, int indent)
1448 {
1449 	vdev_t *kid;
1450 	int ret;
1451 
1452 	if (vdev->v_islog) {
1453 		(void) pager_output("        logs\n");
1454 		indent++;
1455 	}
1456 
1457 	ret = print_state(indent, vdev->v_name, vdev->v_state);
1458 	if (ret != 0)
1459 		return (ret);
1460 
1461 	STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) {
1462 		ret = vdev_status(kid, indent + 1);
1463 		if (ret != 0)
1464 			return (ret);
1465 	}
1466 	return (ret);
1467 }
1468 
1469 static int
1470 spa_status(spa_t *spa)
1471 {
1472 	static char bootfs[ZFS_MAXNAMELEN];
1473 	uint64_t rootid;
1474 	vdev_list_t *vlist;
1475 	vdev_t *vdev;
1476 	int good_kids, bad_kids, degraded_kids, ret;
1477 	vdev_state_t state;
1478 
1479 	ret = pager_printf("  pool: %s\n", spa->spa_name);
1480 	if (ret != 0)
1481 		return (ret);
1482 
1483 	if (zfs_get_root(spa, &rootid) == 0 &&
1484 	    zfs_rlookup(spa, rootid, bootfs) == 0) {
1485 		if (bootfs[0] == '\0')
1486 			ret = pager_printf("bootfs: %s\n", spa->spa_name);
1487 		else
1488 			ret = pager_printf("bootfs: %s/%s\n", spa->spa_name,
1489 			    bootfs);
1490 		if (ret != 0)
1491 			return (ret);
1492 	}
1493 	ret = pager_printf("config:\n\n");
1494 	if (ret != 0)
1495 		return (ret);
1496 	ret = pager_printf(STATUS_FORMAT, "NAME", "STATE");
1497 	if (ret != 0)
1498 		return (ret);
1499 
1500 	good_kids = 0;
1501 	degraded_kids = 0;
1502 	bad_kids = 0;
1503 	vlist = &spa->spa_root_vdev->v_children;
1504 	STAILQ_FOREACH(vdev, vlist, v_childlink) {
1505 		if (vdev->v_state == VDEV_STATE_HEALTHY)
1506 			good_kids++;
1507 		else if (vdev->v_state == VDEV_STATE_DEGRADED)
1508 			degraded_kids++;
1509 		else
1510 			bad_kids++;
1511 	}
1512 
1513 	state = VDEV_STATE_CLOSED;
1514 	if (good_kids > 0 && (degraded_kids + bad_kids) == 0)
1515 		state = VDEV_STATE_HEALTHY;
1516 	else if ((good_kids + degraded_kids) > 0)
1517 		state = VDEV_STATE_DEGRADED;
1518 
1519 	ret = print_state(0, spa->spa_name, state);
1520 	if (ret != 0)
1521 		return (ret);
1522 
1523 	STAILQ_FOREACH(vdev, vlist, v_childlink) {
1524 		ret = vdev_status(vdev, 1);
1525 		if (ret != 0)
1526 			return (ret);
1527 	}
1528 	return (ret);
1529 }
1530 
1531 static int
1532 spa_all_status(void)
1533 {
1534 	spa_t *spa;
1535 	int first = 1, ret = 0;
1536 
1537 	STAILQ_FOREACH(spa, &zfs_pools, spa_link) {
1538 		if (!first) {
1539 			ret = pager_printf("\n");
1540 			if (ret != 0)
1541 				return (ret);
1542 		}
1543 		first = 0;
1544 		ret = spa_status(spa);
1545 		if (ret != 0)
1546 			return (ret);
1547 	}
1548 	return (ret);
1549 }
1550 
1551 static uint64_t
1552 vdev_label_offset(uint64_t psize, int l, uint64_t offset)
1553 {
1554 	uint64_t label_offset;
1555 
1556 	if (l < VDEV_LABELS / 2)
1557 		label_offset = 0;
1558 	else
1559 		label_offset = psize - VDEV_LABELS * sizeof (vdev_label_t);
1560 
1561 	return (offset + l * sizeof (vdev_label_t) + label_offset);
1562 }
1563 
1564 static int
1565 vdev_uberblock_compare(const uberblock_t *ub1, const uberblock_t *ub2)
1566 {
1567 	unsigned int seq1 = 0;
1568 	unsigned int seq2 = 0;
1569 	int cmp = AVL_CMP(ub1->ub_txg, ub2->ub_txg);
1570 
1571 	if (cmp != 0)
1572 		return (cmp);
1573 
1574 	cmp = AVL_CMP(ub1->ub_timestamp, ub2->ub_timestamp);
1575 	if (cmp != 0)
1576 		return (cmp);
1577 
1578 	if (MMP_VALID(ub1) && MMP_SEQ_VALID(ub1))
1579 		seq1 = MMP_SEQ(ub1);
1580 
1581 	if (MMP_VALID(ub2) && MMP_SEQ_VALID(ub2))
1582 		seq2 = MMP_SEQ(ub2);
1583 
1584 	return (AVL_CMP(seq1, seq2));
1585 }
1586 
1587 static int
1588 uberblock_verify(uberblock_t *ub)
1589 {
1590 	if (ub->ub_magic == BSWAP_64((uint64_t)UBERBLOCK_MAGIC)) {
1591 		byteswap_uint64_array(ub, sizeof (uberblock_t));
1592 	}
1593 
1594 	if (ub->ub_magic != UBERBLOCK_MAGIC ||
1595 	    !SPA_VERSION_IS_SUPPORTED(ub->ub_version))
1596 		return (EINVAL);
1597 
1598 	return (0);
1599 }
1600 
1601 static int
1602 vdev_label_read(vdev_t *vd, int l, void *buf, uint64_t offset,
1603     size_t size)
1604 {
1605 	blkptr_t bp;
1606 	off_t off;
1607 
1608 	off = vdev_label_offset(vd->v_psize, l, offset);
1609 
1610 	BP_ZERO(&bp);
1611 	BP_SET_LSIZE(&bp, size);
1612 	BP_SET_PSIZE(&bp, size);
1613 	BP_SET_CHECKSUM(&bp, ZIO_CHECKSUM_LABEL);
1614 	BP_SET_COMPRESS(&bp, ZIO_COMPRESS_OFF);
1615 	DVA_SET_OFFSET(BP_IDENTITY(&bp), off);
1616 	ZIO_SET_CHECKSUM(&bp.blk_cksum, off, 0, 0, 0);
1617 
1618 	return (vdev_read_phys(vd, &bp, buf, off, size));
1619 }
1620 
1621 /*
1622  * We do need to be sure we write to correct location.
1623  * Our vdev label does consist of 4 fields:
1624  * pad1 (8k), reserved.
1625  * bootenv (8k), checksummed, previously reserved, may contian garbage.
1626  * vdev_phys (112k), checksummed
1627  * uberblock ring (128k), checksummed.
1628  *
1629  * Since bootenv area may contain garbage, we can not reliably read it, as
1630  * we can get checksum errors.
1631  * Next best thing is vdev_phys - it is just after bootenv. It still may
1632  * be corrupted, but in such case we will miss this one write.
1633  */
1634 static int
1635 vdev_label_write_validate(vdev_t *vd, int l, uint64_t offset)
1636 {
1637 	uint64_t off, o_phys;
1638 	void *buf;
1639 	size_t size = VDEV_PHYS_SIZE;
1640 	int rc;
1641 
1642 	o_phys = offsetof(vdev_label_t, vl_vdev_phys);
1643 	off = vdev_label_offset(vd->v_psize, l, o_phys);
1644 
1645 	/* off should be 8K from bootenv */
1646 	if (vdev_label_offset(vd->v_psize, l, offset) + VDEV_PAD_SIZE != off)
1647 		return (EINVAL);
1648 
1649 	buf = malloc(size);
1650 	if (buf == NULL)
1651 		return (ENOMEM);
1652 
1653 	/* Read vdev_phys */
1654 	rc = vdev_label_read(vd, l, buf, o_phys, size);
1655 	free(buf);
1656 	return (rc);
1657 }
1658 
1659 static int
1660 vdev_label_write(vdev_t *vd, int l, vdev_boot_envblock_t *be, uint64_t offset)
1661 {
1662 	zio_checksum_info_t *ci;
1663 	zio_cksum_t cksum;
1664 	off_t off;
1665 	size_t size = VDEV_PAD_SIZE;
1666 	int rc;
1667 
1668 	if (vd->v_phys_write == NULL)
1669 		return (ENOTSUP);
1670 
1671 	off = vdev_label_offset(vd->v_psize, l, offset);
1672 
1673 	rc = vdev_label_write_validate(vd, l, offset);
1674 	if (rc != 0) {
1675 		return (rc);
1676 	}
1677 
1678 	ci = &zio_checksum_table[ZIO_CHECKSUM_LABEL];
1679 	be->vbe_zbt.zec_magic = ZEC_MAGIC;
1680 	zio_checksum_label_verifier(&be->vbe_zbt.zec_cksum, off);
1681 	ci->ci_func[0](be, size, NULL, &cksum);
1682 	be->vbe_zbt.zec_cksum = cksum;
1683 
1684 	return (vdev_write_phys(vd, be, off, size));
1685 }
1686 
1687 static int
1688 vdev_write_bootenv_impl(vdev_t *vdev, vdev_boot_envblock_t *be)
1689 {
1690 	vdev_t *kid;
1691 	int rv = 0, rc;
1692 
1693 	STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) {
1694 		if (kid->v_state != VDEV_STATE_HEALTHY)
1695 			continue;
1696 		rc = vdev_write_bootenv_impl(kid, be);
1697 		if (rv == 0)
1698 			rv = rc;
1699 	}
1700 
1701 	/*
1702 	 * Non-leaf vdevs do not have v_phys_write.
1703 	 */
1704 	if (vdev->v_phys_write == NULL)
1705 		return (rv);
1706 
1707 	for (int l = 0; l < VDEV_LABELS; l++) {
1708 		rc = vdev_label_write(vdev, l, be,
1709 		    offsetof(vdev_label_t, vl_be));
1710 		if (rc != 0) {
1711 			printf("failed to write bootenv to %s label %d: %d\n",
1712 			    vdev->v_name ? vdev->v_name : "unknown", l, rc);
1713 			rv = rc;
1714 		}
1715 	}
1716 	return (rv);
1717 }
1718 
1719 int
1720 vdev_write_bootenv(vdev_t *vdev, nvlist_t *nvl)
1721 {
1722 	vdev_boot_envblock_t *be;
1723 	nvlist_t nv, *nvp;
1724 	uint64_t version;
1725 	int rv;
1726 
1727 	if (nvl->nv_size > sizeof(be->vbe_bootenv))
1728 		return (E2BIG);
1729 
1730 	version = VB_RAW;
1731 	nvp = vdev_read_bootenv(vdev);
1732 	if (nvp != NULL) {
1733 		nvlist_find(nvp, BOOTENV_VERSION, DATA_TYPE_UINT64, NULL,
1734 		    &version, NULL);
1735 		nvlist_destroy(nvp);
1736 	}
1737 
1738 	be = calloc(1, sizeof(*be));
1739 	if (be == NULL)
1740 		return (ENOMEM);
1741 
1742 	be->vbe_version = version;
1743 	switch (version) {
1744 	case VB_RAW:
1745 		/*
1746 		 * If there is no envmap, we will just wipe bootenv.
1747 		 */
1748 		nvlist_find(nvl, GRUB_ENVMAP, DATA_TYPE_STRING, NULL,
1749 		    be->vbe_bootenv, NULL);
1750 		rv = 0;
1751 		break;
1752 
1753 	case VB_NVLIST:
1754 		nv.nv_header = nvl->nv_header;
1755 		nv.nv_asize = nvl->nv_asize;
1756 		nv.nv_size = nvl->nv_size;
1757 
1758 		bcopy(&nv.nv_header, be->vbe_bootenv, sizeof(nv.nv_header));
1759 		nv.nv_data = be->vbe_bootenv + sizeof(nvs_header_t);
1760 		bcopy(nvl->nv_data, nv.nv_data, nv.nv_size);
1761 		rv = nvlist_export(&nv);
1762 		break;
1763 
1764 	default:
1765 		rv = EINVAL;
1766 		break;
1767 	}
1768 
1769 	if (rv == 0) {
1770 		be->vbe_version = htobe64(be->vbe_version);
1771 		rv = vdev_write_bootenv_impl(vdev, be);
1772 	}
1773 	free(be);
1774 	return (rv);
1775 }
1776 
1777 /*
1778  * Read the bootenv area from pool label, return the nvlist from it.
1779  * We return from first successful read.
1780  */
1781 nvlist_t *
1782 vdev_read_bootenv(vdev_t *vdev)
1783 {
1784 	vdev_t *kid;
1785 	nvlist_t *benv;
1786 	vdev_boot_envblock_t *be;
1787 	char *command;
1788 	bool ok;
1789 	int rv;
1790 
1791 	STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) {
1792 		if (kid->v_state != VDEV_STATE_HEALTHY)
1793 			continue;
1794 
1795 		benv = vdev_read_bootenv(kid);
1796 		if (benv != NULL)
1797 			return (benv);
1798 	}
1799 
1800 	be = malloc(sizeof (*be));
1801 	if (be == NULL)
1802 		return (NULL);
1803 
1804 	rv = 0;
1805 	for (int l = 0; l < VDEV_LABELS; l++) {
1806 		rv = vdev_label_read(vdev, l, be,
1807 		    offsetof(vdev_label_t, vl_be),
1808 		    sizeof (*be));
1809 		if (rv == 0)
1810 			break;
1811 	}
1812 	if (rv != 0) {
1813 		free(be);
1814 		return (NULL);
1815 	}
1816 
1817 	be->vbe_version = be64toh(be->vbe_version);
1818 	switch (be->vbe_version) {
1819 	case VB_RAW:
1820 		/*
1821 		 * we have textual data in vbe_bootenv, create nvlist
1822 		 * with key "envmap".
1823 		 */
1824 		benv = nvlist_create(NV_UNIQUE_NAME);
1825 		if (benv != NULL) {
1826 			if (*be->vbe_bootenv == '\0') {
1827 				nvlist_add_uint64(benv, BOOTENV_VERSION,
1828 				    VB_NVLIST);
1829 				break;
1830 			}
1831 			nvlist_add_uint64(benv, BOOTENV_VERSION, VB_RAW);
1832 			be->vbe_bootenv[sizeof (be->vbe_bootenv) - 1] = '\0';
1833 			nvlist_add_string(benv, GRUB_ENVMAP, be->vbe_bootenv);
1834 		}
1835 		break;
1836 
1837 	case VB_NVLIST:
1838 		benv = nvlist_import(be->vbe_bootenv, sizeof(be->vbe_bootenv));
1839 		break;
1840 
1841 	default:
1842 		command = (char *)be;
1843 		ok = false;
1844 
1845 		/* Check for legacy zfsbootcfg command string */
1846 		for (int i = 0; command[i] != '\0'; i++) {
1847 			if (iscntrl(command[i])) {
1848 				ok = false;
1849 				break;
1850 			} else {
1851 				ok = true;
1852 			}
1853 		}
1854 		benv = nvlist_create(NV_UNIQUE_NAME);
1855 		if (benv != NULL) {
1856 			if (ok)
1857 				nvlist_add_string(benv, FREEBSD_BOOTONCE,
1858 				    command);
1859 			else
1860 				nvlist_add_uint64(benv, BOOTENV_VERSION,
1861 				    VB_NVLIST);
1862 		}
1863 		break;
1864 	}
1865 	free(be);
1866 	return (benv);
1867 }
1868 
1869 static uint64_t
1870 vdev_get_label_asize(nvlist_t *nvl)
1871 {
1872 	nvlist_t *vdevs;
1873 	uint64_t asize;
1874 	const char *type;
1875 	int len;
1876 
1877 	asize = 0;
1878 	/* Get vdev tree */
1879 	if (nvlist_find(nvl, ZPOOL_CONFIG_VDEV_TREE, DATA_TYPE_NVLIST,
1880 	    NULL, &vdevs, NULL) != 0)
1881 		return (asize);
1882 
1883 	/*
1884 	 * Get vdev type. We will calculate asize for raidz, mirror and disk.
1885 	 * For raidz, the asize is raw size of all children.
1886 	 */
1887 	if (nvlist_find(vdevs, ZPOOL_CONFIG_TYPE, DATA_TYPE_STRING,
1888 	    NULL, &type, &len) != 0)
1889 		goto done;
1890 
1891 	if (memcmp(type, VDEV_TYPE_MIRROR, len) != 0 &&
1892 	    memcmp(type, VDEV_TYPE_DISK, len) != 0 &&
1893 	    memcmp(type, VDEV_TYPE_RAIDZ, len) != 0)
1894 		goto done;
1895 
1896 	if (nvlist_find(vdevs, ZPOOL_CONFIG_ASIZE, DATA_TYPE_UINT64,
1897 	    NULL, &asize, NULL) != 0)
1898 		goto done;
1899 
1900 	if (memcmp(type, VDEV_TYPE_RAIDZ, len) == 0) {
1901 		nvlist_t **kids;
1902 		int nkids;
1903 
1904 		if (nvlist_find(vdevs, ZPOOL_CONFIG_CHILDREN,
1905 		    DATA_TYPE_NVLIST_ARRAY, &nkids, &kids, NULL) != 0) {
1906 			asize = 0;
1907 			goto done;
1908 		}
1909 
1910 		asize /= nkids;
1911 		for (int i = 0; i < nkids; i++)
1912 			nvlist_destroy(kids[i]);
1913 		free(kids);
1914 	}
1915 
1916 	asize += VDEV_LABEL_START_SIZE + VDEV_LABEL_END_SIZE;
1917 done:
1918 	nvlist_destroy(vdevs);
1919 	return (asize);
1920 }
1921 
1922 static nvlist_t *
1923 vdev_label_read_config(vdev_t *vd, uint64_t txg)
1924 {
1925 	vdev_phys_t *label;
1926 	uint64_t best_txg = 0;
1927 	uint64_t label_txg = 0;
1928 	uint64_t asize;
1929 	nvlist_t *nvl = NULL, *tmp;
1930 	int error;
1931 
1932 	label = malloc(sizeof (vdev_phys_t));
1933 	if (label == NULL)
1934 		return (NULL);
1935 
1936 	for (int l = 0; l < VDEV_LABELS; l++) {
1937 		if (vdev_label_read(vd, l, label,
1938 		    offsetof(vdev_label_t, vl_vdev_phys),
1939 		    sizeof (vdev_phys_t)))
1940 			continue;
1941 
1942 		tmp = nvlist_import(label->vp_nvlist,
1943 		    sizeof(label->vp_nvlist));
1944 		if (tmp == NULL)
1945 			continue;
1946 
1947 		error = nvlist_find(tmp, ZPOOL_CONFIG_POOL_TXG,
1948 		    DATA_TYPE_UINT64, NULL, &label_txg, NULL);
1949 		if (error != 0 || label_txg == 0) {
1950 			nvlist_destroy(nvl);
1951 			nvl = tmp;
1952 			goto done;
1953 		}
1954 
1955 		if (label_txg <= txg && label_txg > best_txg) {
1956 			best_txg = label_txg;
1957 			nvlist_destroy(nvl);
1958 			nvl = tmp;
1959 			tmp = NULL;
1960 
1961 			/*
1962 			 * Use asize from pool config. We need this
1963 			 * because we can get bad value from BIOS.
1964 			 */
1965 			asize = vdev_get_label_asize(nvl);
1966 			if (asize != 0) {
1967 				vd->v_psize = asize;
1968 			}
1969 		}
1970 		nvlist_destroy(tmp);
1971 	}
1972 
1973 	if (best_txg == 0) {
1974 		nvlist_destroy(nvl);
1975 		nvl = NULL;
1976 	}
1977 done:
1978 	free(label);
1979 	return (nvl);
1980 }
1981 
1982 static void
1983 vdev_uberblock_load(vdev_t *vd, uberblock_t *ub)
1984 {
1985 	uberblock_t *buf;
1986 
1987 	buf = malloc(VDEV_UBERBLOCK_SIZE(vd));
1988 	if (buf == NULL)
1989 		return;
1990 
1991 	for (int l = 0; l < VDEV_LABELS; l++) {
1992 		for (int n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) {
1993 			if (vdev_label_read(vd, l, buf,
1994 			    VDEV_UBERBLOCK_OFFSET(vd, n),
1995 			    VDEV_UBERBLOCK_SIZE(vd)))
1996 				continue;
1997 			if (uberblock_verify(buf) != 0)
1998 				continue;
1999 
2000 			if (vdev_uberblock_compare(buf, ub) > 0)
2001 				*ub = *buf;
2002 		}
2003 	}
2004 	free(buf);
2005 }
2006 
2007 static int
2008 vdev_probe(vdev_phys_read_t *_read, vdev_phys_write_t *_write, void *priv,
2009     spa_t **spap)
2010 {
2011 	vdev_t vtmp;
2012 	spa_t *spa;
2013 	vdev_t *vdev;
2014 	nvlist_t *nvl;
2015 	uint64_t val;
2016 	uint64_t guid, vdev_children;
2017 	uint64_t pool_txg, pool_guid;
2018 	const char *pool_name;
2019 	int rc, namelen;
2020 
2021 	/*
2022 	 * Load the vdev label and figure out which
2023 	 * uberblock is most current.
2024 	 */
2025 	memset(&vtmp, 0, sizeof(vtmp));
2026 	vtmp.v_phys_read = _read;
2027 	vtmp.v_phys_write = _write;
2028 	vtmp.v_priv = priv;
2029 	vtmp.v_psize = P2ALIGN(ldi_get_size(priv),
2030 	    (uint64_t)sizeof (vdev_label_t));
2031 
2032 	/* Test for minimum device size. */
2033 	if (vtmp.v_psize < SPA_MINDEVSIZE)
2034 		return (EIO);
2035 
2036 	nvl = vdev_label_read_config(&vtmp, UINT64_MAX);
2037 	if (nvl == NULL)
2038 		return (EIO);
2039 
2040 	if (nvlist_find(nvl, ZPOOL_CONFIG_VERSION, DATA_TYPE_UINT64,
2041 	    NULL, &val, NULL) != 0) {
2042 		nvlist_destroy(nvl);
2043 		return (EIO);
2044 	}
2045 
2046 	if (!SPA_VERSION_IS_SUPPORTED(val)) {
2047 		printf("ZFS: unsupported ZFS version %u (should be %u)\n",
2048 		    (unsigned)val, (unsigned)SPA_VERSION);
2049 		nvlist_destroy(nvl);
2050 		return (EIO);
2051 	}
2052 
2053 	/* Check ZFS features for read */
2054 	rc = nvlist_check_features_for_read(nvl);
2055 	if (rc != 0) {
2056 		nvlist_destroy(nvl);
2057 		return (EIO);
2058 	}
2059 
2060 	if (nvlist_find(nvl, ZPOOL_CONFIG_POOL_STATE, DATA_TYPE_UINT64,
2061 	    NULL, &val, NULL) != 0) {
2062 		nvlist_destroy(nvl);
2063 		return (EIO);
2064 	}
2065 
2066 	if (val == POOL_STATE_DESTROYED) {
2067 		/* We don't boot only from destroyed pools. */
2068 		nvlist_destroy(nvl);
2069 		return (EIO);
2070 	}
2071 
2072 	if (nvlist_find(nvl, ZPOOL_CONFIG_POOL_TXG, DATA_TYPE_UINT64,
2073 	    NULL, &pool_txg, NULL) != 0 ||
2074 	    nvlist_find(nvl, ZPOOL_CONFIG_POOL_GUID, DATA_TYPE_UINT64,
2075 	    NULL, &pool_guid, NULL) != 0 ||
2076 	    nvlist_find(nvl, ZPOOL_CONFIG_POOL_NAME, DATA_TYPE_STRING,
2077 	    NULL, &pool_name, &namelen) != 0) {
2078 		/*
2079 		 * Cache and spare devices end up here - just ignore
2080 		 * them.
2081 		 */
2082 		nvlist_destroy(nvl);
2083 		return (EIO);
2084 	}
2085 
2086 	/*
2087 	 * Create the pool if this is the first time we've seen it.
2088 	 */
2089 	spa = spa_find_by_guid(pool_guid);
2090 	if (spa == NULL) {
2091 		char *name;
2092 
2093 		nvlist_find(nvl, ZPOOL_CONFIG_VDEV_CHILDREN,
2094 		    DATA_TYPE_UINT64, NULL, &vdev_children, NULL);
2095 		name = malloc(namelen + 1);
2096 		if (name == NULL) {
2097 			nvlist_destroy(nvl);
2098 			return (ENOMEM);
2099 		}
2100 		bcopy(pool_name, name, namelen);
2101 		name[namelen] = '\0';
2102 		spa = spa_create(pool_guid, name);
2103 		free(name);
2104 		if (spa == NULL) {
2105 			nvlist_destroy(nvl);
2106 			return (ENOMEM);
2107 		}
2108 		spa->spa_root_vdev->v_nchildren = vdev_children;
2109 	}
2110 	if (pool_txg > spa->spa_txg)
2111 		spa->spa_txg = pool_txg;
2112 
2113 	/*
2114 	 * Get the vdev tree and create our in-core copy of it.
2115 	 * If we already have a vdev with this guid, this must
2116 	 * be some kind of alias (overlapping slices, dangerously dedicated
2117 	 * disks etc).
2118 	 */
2119 	if (nvlist_find(nvl, ZPOOL_CONFIG_GUID, DATA_TYPE_UINT64,
2120 	    NULL, &guid, NULL) != 0) {
2121 		nvlist_destroy(nvl);
2122 		return (EIO);
2123 	}
2124 	vdev = vdev_find(guid);
2125 	/* Has this vdev already been inited? */
2126 	if (vdev && vdev->v_phys_read) {
2127 		nvlist_destroy(nvl);
2128 		return (EIO);
2129 	}
2130 
2131 	rc = vdev_init_from_label(spa, nvl);
2132 	nvlist_destroy(nvl);
2133 	if (rc != 0)
2134 		return (rc);
2135 
2136 	/*
2137 	 * We should already have created an incomplete vdev for this
2138 	 * vdev. Find it and initialise it with our read proc.
2139 	 */
2140 	vdev = vdev_find(guid);
2141 	if (vdev != NULL) {
2142 		vdev->v_phys_read = _read;
2143 		vdev->v_phys_write = _write;
2144 		vdev->v_priv = priv;
2145 		vdev->v_psize = vtmp.v_psize;
2146 		/*
2147 		 * If no other state is set, mark vdev healthy.
2148 		 */
2149 		if (vdev->v_state == VDEV_STATE_UNKNOWN)
2150 			vdev->v_state = VDEV_STATE_HEALTHY;
2151 	} else {
2152 		printf("ZFS: inconsistent nvlist contents\n");
2153 		return (EIO);
2154 	}
2155 
2156 	if (vdev->v_islog)
2157 		spa->spa_with_log = vdev->v_islog;
2158 
2159 	/*
2160 	 * Re-evaluate top-level vdev state.
2161 	 */
2162 	vdev_set_state(vdev->v_top);
2163 
2164 	/*
2165 	 * Ok, we are happy with the pool so far. Lets find
2166 	 * the best uberblock and then we can actually access
2167 	 * the contents of the pool.
2168 	 */
2169 	vdev_uberblock_load(vdev, spa->spa_uberblock);
2170 
2171 	if (spap != NULL)
2172 		*spap = spa;
2173 	return (0);
2174 }
2175 
2176 static int
2177 ilog2(int n)
2178 {
2179 	int v;
2180 
2181 	for (v = 0; v < 32; v++)
2182 		if (n == (1 << v))
2183 			return (v);
2184 	return (-1);
2185 }
2186 
2187 static int
2188 zio_read_gang(const spa_t *spa, const blkptr_t *bp, void *buf)
2189 {
2190 	blkptr_t gbh_bp;
2191 	zio_gbh_phys_t zio_gb;
2192 	char *pbuf;
2193 	int i;
2194 
2195 	/* Artificial BP for gang block header. */
2196 	gbh_bp = *bp;
2197 	BP_SET_PSIZE(&gbh_bp, SPA_GANGBLOCKSIZE);
2198 	BP_SET_LSIZE(&gbh_bp, SPA_GANGBLOCKSIZE);
2199 	BP_SET_CHECKSUM(&gbh_bp, ZIO_CHECKSUM_GANG_HEADER);
2200 	BP_SET_COMPRESS(&gbh_bp, ZIO_COMPRESS_OFF);
2201 	for (i = 0; i < SPA_DVAS_PER_BP; i++)
2202 		DVA_SET_GANG(&gbh_bp.blk_dva[i], 0);
2203 
2204 	/* Read gang header block using the artificial BP. */
2205 	if (zio_read(spa, &gbh_bp, &zio_gb))
2206 		return (EIO);
2207 
2208 	pbuf = buf;
2209 	for (i = 0; i < SPA_GBH_NBLKPTRS; i++) {
2210 		blkptr_t *gbp = &zio_gb.zg_blkptr[i];
2211 
2212 		if (BP_IS_HOLE(gbp))
2213 			continue;
2214 		if (zio_read(spa, gbp, pbuf))
2215 			return (EIO);
2216 		pbuf += BP_GET_PSIZE(gbp);
2217 	}
2218 
2219 	if (zio_checksum_verify(spa, bp, buf))
2220 		return (EIO);
2221 	return (0);
2222 }
2223 
2224 static int
2225 zio_read(const spa_t *spa, const blkptr_t *bp, void *buf)
2226 {
2227 	int cpfunc = BP_GET_COMPRESS(bp);
2228 	uint64_t align, size;
2229 	void *pbuf;
2230 	int i, error;
2231 
2232 	/*
2233 	 * Process data embedded in block pointer
2234 	 */
2235 	if (BP_IS_EMBEDDED(bp)) {
2236 		ASSERT(BPE_GET_ETYPE(bp) == BP_EMBEDDED_TYPE_DATA);
2237 
2238 		size = BPE_GET_PSIZE(bp);
2239 		ASSERT(size <= BPE_PAYLOAD_SIZE);
2240 
2241 		if (cpfunc != ZIO_COMPRESS_OFF)
2242 			pbuf = malloc(size);
2243 		else
2244 			pbuf = buf;
2245 
2246 		if (pbuf == NULL)
2247 			return (ENOMEM);
2248 
2249 		decode_embedded_bp_compressed(bp, pbuf);
2250 		error = 0;
2251 
2252 		if (cpfunc != ZIO_COMPRESS_OFF) {
2253 			error = zio_decompress_data(cpfunc, pbuf,
2254 			    size, buf, BP_GET_LSIZE(bp));
2255 			free(pbuf);
2256 		}
2257 		if (error != 0)
2258 			printf("ZFS: i/o error - unable to decompress "
2259 			    "block pointer data, error %d\n", error);
2260 		return (error);
2261 	}
2262 
2263 	error = EIO;
2264 
2265 	for (i = 0; i < SPA_DVAS_PER_BP; i++) {
2266 		const dva_t *dva = &bp->blk_dva[i];
2267 		vdev_t *vdev;
2268 		vdev_list_t *vlist;
2269 		uint64_t vdevid;
2270 		off_t offset;
2271 
2272 		if (!dva->dva_word[0] && !dva->dva_word[1])
2273 			continue;
2274 
2275 		vdevid = DVA_GET_VDEV(dva);
2276 		offset = DVA_GET_OFFSET(dva);
2277 		vlist = &spa->spa_root_vdev->v_children;
2278 		STAILQ_FOREACH(vdev, vlist, v_childlink) {
2279 			if (vdev->v_id == vdevid)
2280 				break;
2281 		}
2282 		if (!vdev || !vdev->v_read)
2283 			continue;
2284 
2285 		size = BP_GET_PSIZE(bp);
2286 		if (vdev->v_read == vdev_raidz_read) {
2287 			align = 1ULL << vdev->v_ashift;
2288 			if (P2PHASE(size, align) != 0)
2289 				size = P2ROUNDUP(size, align);
2290 		}
2291 		if (size != BP_GET_PSIZE(bp) || cpfunc != ZIO_COMPRESS_OFF)
2292 			pbuf = malloc(size);
2293 		else
2294 			pbuf = buf;
2295 
2296 		if (pbuf == NULL) {
2297 			error = ENOMEM;
2298 			break;
2299 		}
2300 
2301 		if (DVA_GET_GANG(dva))
2302 			error = zio_read_gang(spa, bp, pbuf);
2303 		else
2304 			error = vdev->v_read(vdev, bp, pbuf, offset, size);
2305 		if (error == 0) {
2306 			if (cpfunc != ZIO_COMPRESS_OFF)
2307 				error = zio_decompress_data(cpfunc, pbuf,
2308 				    BP_GET_PSIZE(bp), buf, BP_GET_LSIZE(bp));
2309 			else if (size != BP_GET_PSIZE(bp))
2310 				bcopy(pbuf, buf, BP_GET_PSIZE(bp));
2311 		} else {
2312 			printf("zio_read error: %d\n", error);
2313 		}
2314 		if (buf != pbuf)
2315 			free(pbuf);
2316 		if (error == 0)
2317 			break;
2318 	}
2319 	if (error != 0)
2320 		printf("ZFS: i/o error - all block copies unavailable\n");
2321 
2322 	return (error);
2323 }
2324 
2325 static int
2326 dnode_read(const spa_t *spa, const dnode_phys_t *dnode, off_t offset,
2327     void *buf, size_t buflen)
2328 {
2329 	int ibshift = dnode->dn_indblkshift - SPA_BLKPTRSHIFT;
2330 	int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
2331 	int nlevels = dnode->dn_nlevels;
2332 	int i, rc;
2333 
2334 	if (bsize > SPA_MAXBLOCKSIZE) {
2335 		printf("ZFS: I/O error - blocks larger than %llu are not "
2336 		    "supported\n", SPA_MAXBLOCKSIZE);
2337 		return (EIO);
2338 	}
2339 
2340 	/*
2341 	 * Handle odd block sizes, mirrors dmu_read_impl().  Data can't exist
2342 	 * past the first block, so we'll clip the read to the portion of the
2343 	 * buffer within bsize and zero out the remainder.
2344 	 */
2345 	if (dnode->dn_maxblkid == 0) {
2346 		size_t newbuflen;
2347 
2348 		newbuflen = offset > bsize ? 0 : MIN(buflen, bsize - offset);
2349 		bzero((char *)buf + newbuflen, buflen - newbuflen);
2350 		buflen = newbuflen;
2351 	}
2352 
2353 	/*
2354 	 * Note: bsize may not be a power of two here so we need to do an
2355 	 * actual divide rather than a bitshift.
2356 	 */
2357 	while (buflen > 0) {
2358 		uint64_t bn = offset / bsize;
2359 		int boff = offset % bsize;
2360 		int ibn;
2361 		const blkptr_t *indbp;
2362 		blkptr_t bp;
2363 
2364 		if (bn > dnode->dn_maxblkid)
2365 			return (EIO);
2366 
2367 		if (dnode == dnode_cache_obj && bn == dnode_cache_bn)
2368 			goto cached;
2369 
2370 		indbp = dnode->dn_blkptr;
2371 		for (i = 0; i < nlevels; i++) {
2372 			/*
2373 			 * Copy the bp from the indirect array so that
2374 			 * we can re-use the scratch buffer for multi-level
2375 			 * objects.
2376 			 */
2377 			ibn = bn >> ((nlevels - i - 1) * ibshift);
2378 			ibn &= ((1 << ibshift) - 1);
2379 			bp = indbp[ibn];
2380 			if (BP_IS_HOLE(&bp)) {
2381 				memset(dnode_cache_buf, 0, bsize);
2382 				break;
2383 			}
2384 			rc = zio_read(spa, &bp, dnode_cache_buf);
2385 			if (rc)
2386 				return (rc);
2387 			indbp = (const blkptr_t *) dnode_cache_buf;
2388 		}
2389 		dnode_cache_obj = dnode;
2390 		dnode_cache_bn = bn;
2391 	cached:
2392 
2393 		/*
2394 		 * The buffer contains our data block. Copy what we
2395 		 * need from it and loop.
2396 		 */
2397 		i = bsize - boff;
2398 		if (i > buflen) i = buflen;
2399 		memcpy(buf, &dnode_cache_buf[boff], i);
2400 		buf = ((char *)buf) + i;
2401 		offset += i;
2402 		buflen -= i;
2403 	}
2404 
2405 	return (0);
2406 }
2407 
2408 /*
2409  * Lookup a value in a microzap directory.
2410  */
2411 static int
2412 mzap_lookup(const mzap_phys_t *mz, size_t size, const char *name,
2413     uint64_t *value)
2414 {
2415 	const mzap_ent_phys_t *mze;
2416 	int chunks, i;
2417 
2418 	/*
2419 	 * Microzap objects use exactly one block. Read the whole
2420 	 * thing.
2421 	 */
2422 	chunks = size / MZAP_ENT_LEN - 1;
2423 	for (i = 0; i < chunks; i++) {
2424 		mze = &mz->mz_chunk[i];
2425 		if (strcmp(mze->mze_name, name) == 0) {
2426 			*value = mze->mze_value;
2427 			return (0);
2428 		}
2429 	}
2430 
2431 	return (ENOENT);
2432 }
2433 
2434 /*
2435  * Compare a name with a zap leaf entry. Return non-zero if the name
2436  * matches.
2437  */
2438 static int
2439 fzap_name_equal(const zap_leaf_t *zl, const zap_leaf_chunk_t *zc,
2440     const char *name)
2441 {
2442 	size_t namelen;
2443 	const zap_leaf_chunk_t *nc;
2444 	const char *p;
2445 
2446 	namelen = zc->l_entry.le_name_numints;
2447 
2448 	nc = &ZAP_LEAF_CHUNK(zl, zc->l_entry.le_name_chunk);
2449 	p = name;
2450 	while (namelen > 0) {
2451 		size_t len;
2452 
2453 		len = namelen;
2454 		if (len > ZAP_LEAF_ARRAY_BYTES)
2455 			len = ZAP_LEAF_ARRAY_BYTES;
2456 		if (memcmp(p, nc->l_array.la_array, len))
2457 			return (0);
2458 		p += len;
2459 		namelen -= len;
2460 		nc = &ZAP_LEAF_CHUNK(zl, nc->l_array.la_next);
2461 	}
2462 
2463 	return (1);
2464 }
2465 
2466 /*
2467  * Extract a uint64_t value from a zap leaf entry.
2468  */
2469 static uint64_t
2470 fzap_leaf_value(const zap_leaf_t *zl, const zap_leaf_chunk_t *zc)
2471 {
2472 	const zap_leaf_chunk_t *vc;
2473 	int i;
2474 	uint64_t value;
2475 	const uint8_t *p;
2476 
2477 	vc = &ZAP_LEAF_CHUNK(zl, zc->l_entry.le_value_chunk);
2478 	for (i = 0, value = 0, p = vc->l_array.la_array; i < 8; i++) {
2479 		value = (value << 8) | p[i];
2480 	}
2481 
2482 	return (value);
2483 }
2484 
2485 static void
2486 stv(int len, void *addr, uint64_t value)
2487 {
2488 	switch (len) {
2489 	case 1:
2490 		*(uint8_t *)addr = value;
2491 		return;
2492 	case 2:
2493 		*(uint16_t *)addr = value;
2494 		return;
2495 	case 4:
2496 		*(uint32_t *)addr = value;
2497 		return;
2498 	case 8:
2499 		*(uint64_t *)addr = value;
2500 		return;
2501 	}
2502 }
2503 
2504 /*
2505  * Extract a array from a zap leaf entry.
2506  */
2507 static void
2508 fzap_leaf_array(const zap_leaf_t *zl, const zap_leaf_chunk_t *zc,
2509     uint64_t integer_size, uint64_t num_integers, void *buf)
2510 {
2511 	uint64_t array_int_len = zc->l_entry.le_value_intlen;
2512 	uint64_t value = 0;
2513 	uint64_t *u64 = buf;
2514 	char *p = buf;
2515 	int len = MIN(zc->l_entry.le_value_numints, num_integers);
2516 	int chunk = zc->l_entry.le_value_chunk;
2517 	int byten = 0;
2518 
2519 	if (integer_size == 8 && len == 1) {
2520 		*u64 = fzap_leaf_value(zl, zc);
2521 		return;
2522 	}
2523 
2524 	while (len > 0) {
2525 		struct zap_leaf_array *la = &ZAP_LEAF_CHUNK(zl, chunk).l_array;
2526 		int i;
2527 
2528 		ASSERT3U(chunk, <, ZAP_LEAF_NUMCHUNKS(zl));
2529 		for (i = 0; i < ZAP_LEAF_ARRAY_BYTES && len > 0; i++) {
2530 			value = (value << 8) | la->la_array[i];
2531 			byten++;
2532 			if (byten == array_int_len) {
2533 				stv(integer_size, p, value);
2534 				byten = 0;
2535 				len--;
2536 				if (len == 0)
2537 					return;
2538 				p += integer_size;
2539 			}
2540 		}
2541 		chunk = la->la_next;
2542 	}
2543 }
2544 
2545 static int
2546 fzap_check_size(uint64_t integer_size, uint64_t num_integers)
2547 {
2548 
2549 	switch (integer_size) {
2550 	case 1:
2551 	case 2:
2552 	case 4:
2553 	case 8:
2554 		break;
2555 	default:
2556 		return (EINVAL);
2557 	}
2558 
2559 	if (integer_size * num_integers > ZAP_MAXVALUELEN)
2560 		return (E2BIG);
2561 
2562 	return (0);
2563 }
2564 
2565 static void
2566 zap_leaf_free(zap_leaf_t *leaf)
2567 {
2568 	free(leaf->l_phys);
2569 	free(leaf);
2570 }
2571 
2572 static int
2573 zap_get_leaf_byblk(fat_zap_t *zap, uint64_t blk, zap_leaf_t **lp)
2574 {
2575 	int bs = FZAP_BLOCK_SHIFT(zap);
2576 	int err;
2577 
2578 	*lp = malloc(sizeof(**lp));
2579 	if (*lp == NULL)
2580 		return (ENOMEM);
2581 
2582 	(*lp)->l_bs = bs;
2583 	(*lp)->l_phys = malloc(1 << bs);
2584 
2585 	if ((*lp)->l_phys == NULL) {
2586 		free(*lp);
2587 		return (ENOMEM);
2588 	}
2589 	err = dnode_read(zap->zap_spa, zap->zap_dnode, blk << bs, (*lp)->l_phys,
2590 	    1 << bs);
2591 	if (err != 0) {
2592 		zap_leaf_free(*lp);
2593 	}
2594 	return (err);
2595 }
2596 
2597 static int
2598 zap_table_load(fat_zap_t *zap, zap_table_phys_t *tbl, uint64_t idx,
2599     uint64_t *valp)
2600 {
2601 	int bs = FZAP_BLOCK_SHIFT(zap);
2602 	uint64_t blk = idx >> (bs - 3);
2603 	uint64_t off = idx & ((1 << (bs - 3)) - 1);
2604 	uint64_t *buf;
2605 	int rc;
2606 
2607 	buf = malloc(1 << zap->zap_block_shift);
2608 	if (buf == NULL)
2609 		return (ENOMEM);
2610 	rc = dnode_read(zap->zap_spa, zap->zap_dnode, (tbl->zt_blk + blk) << bs,
2611 	    buf, 1 << zap->zap_block_shift);
2612 	if (rc == 0)
2613 		*valp = buf[off];
2614 	free(buf);
2615 	return (rc);
2616 }
2617 
2618 static int
2619 zap_idx_to_blk(fat_zap_t *zap, uint64_t idx, uint64_t *valp)
2620 {
2621 	if (zap->zap_phys->zap_ptrtbl.zt_numblks == 0) {
2622 		*valp = ZAP_EMBEDDED_PTRTBL_ENT(zap, idx);
2623 		return (0);
2624 	} else {
2625 		return (zap_table_load(zap, &zap->zap_phys->zap_ptrtbl,
2626 		    idx, valp));
2627 	}
2628 }
2629 
2630 #define	ZAP_HASH_IDX(hash, n)	(((n) == 0) ? 0 : ((hash) >> (64 - (n))))
2631 static int
2632 zap_deref_leaf(fat_zap_t *zap, uint64_t h, zap_leaf_t **lp)
2633 {
2634 	uint64_t idx, blk;
2635 	int err;
2636 
2637 	idx = ZAP_HASH_IDX(h, zap->zap_phys->zap_ptrtbl.zt_shift);
2638 	err = zap_idx_to_blk(zap, idx, &blk);
2639 	if (err != 0)
2640 		return (err);
2641 	return (zap_get_leaf_byblk(zap, blk, lp));
2642 }
2643 
2644 #define	CHAIN_END	0xffff	/* end of the chunk chain */
2645 #define	LEAF_HASH(l, h) \
2646 	((ZAP_LEAF_HASH_NUMENTRIES(l)-1) & \
2647 	((h) >> \
2648 	(64 - ZAP_LEAF_HASH_SHIFT(l) - (l)->l_phys->l_hdr.lh_prefix_len)))
2649 #define	LEAF_HASH_ENTPTR(l, h)	(&(l)->l_phys->l_hash[LEAF_HASH(l, h)])
2650 
2651 static int
2652 zap_leaf_lookup(zap_leaf_t *zl, uint64_t hash, const char *name,
2653     uint64_t integer_size, uint64_t num_integers, void *value)
2654 {
2655 	int rc;
2656 	uint16_t *chunkp;
2657 	struct zap_leaf_entry *le;
2658 
2659 	/*
2660 	 * Make sure this chunk matches our hash.
2661 	 */
2662 	if (zl->l_phys->l_hdr.lh_prefix_len > 0 &&
2663 	    zl->l_phys->l_hdr.lh_prefix !=
2664 	    hash >> (64 - zl->l_phys->l_hdr.lh_prefix_len))
2665 		return (EIO);
2666 
2667 	rc = ENOENT;
2668 	for (chunkp = LEAF_HASH_ENTPTR(zl, hash);
2669 	    *chunkp != CHAIN_END; chunkp = &le->le_next) {
2670 		zap_leaf_chunk_t *zc;
2671 		uint16_t chunk = *chunkp;
2672 
2673 		le = ZAP_LEAF_ENTRY(zl, chunk);
2674 		if (le->le_hash != hash)
2675 			continue;
2676 		zc = &ZAP_LEAF_CHUNK(zl, chunk);
2677 		if (fzap_name_equal(zl, zc, name)) {
2678 			if (zc->l_entry.le_value_intlen > integer_size) {
2679 				rc = EINVAL;
2680 			} else {
2681 				fzap_leaf_array(zl, zc, integer_size,
2682 				    num_integers, value);
2683 				rc = 0;
2684 			}
2685 			break;
2686 		}
2687 	}
2688 	return (rc);
2689 }
2690 
2691 /*
2692  * Lookup a value in a fatzap directory.
2693  */
2694 static int
2695 fzap_lookup(const spa_t *spa, const dnode_phys_t *dnode, zap_phys_t *zh,
2696     const char *name, uint64_t integer_size, uint64_t num_integers,
2697     void *value)
2698 {
2699 	int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
2700 	fat_zap_t z;
2701 	zap_leaf_t *zl;
2702 	uint64_t hash;
2703 	int rc;
2704 
2705 	if (zh->zap_magic != ZAP_MAGIC)
2706 		return (EIO);
2707 
2708 	if ((rc = fzap_check_size(integer_size, num_integers)) != 0) {
2709 		return (rc);
2710 	}
2711 
2712 	z.zap_block_shift = ilog2(bsize);
2713 	z.zap_phys = zh;
2714 	z.zap_spa = spa;
2715 	z.zap_dnode = dnode;
2716 
2717 	hash = zap_hash(zh->zap_salt, name);
2718 	rc = zap_deref_leaf(&z, hash, &zl);
2719 	if (rc != 0)
2720 		return (rc);
2721 
2722 	rc = zap_leaf_lookup(zl, hash, name, integer_size, num_integers, value);
2723 
2724 	zap_leaf_free(zl);
2725 	return (rc);
2726 }
2727 
2728 /*
2729  * Lookup a name in a zap object and return its value as a uint64_t.
2730  */
2731 static int
2732 zap_lookup(const spa_t *spa, const dnode_phys_t *dnode, const char *name,
2733     uint64_t integer_size, uint64_t num_integers, void *value)
2734 {
2735 	int rc;
2736 	zap_phys_t *zap;
2737 	size_t size = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
2738 
2739 	zap = malloc(size);
2740 	if (zap == NULL)
2741 		return (ENOMEM);
2742 
2743 	rc = dnode_read(spa, dnode, 0, zap, size);
2744 	if (rc)
2745 		goto done;
2746 
2747 	switch (zap->zap_block_type) {
2748 	case ZBT_MICRO:
2749 		rc = mzap_lookup((const mzap_phys_t *)zap, size, name, value);
2750 		break;
2751 	case ZBT_HEADER:
2752 		rc = fzap_lookup(spa, dnode, zap, name, integer_size,
2753 		    num_integers, value);
2754 		break;
2755 	default:
2756 		printf("ZFS: invalid zap_type=%" PRIx64 "\n",
2757 		    zap->zap_block_type);
2758 		rc = EIO;
2759 	}
2760 done:
2761 	free(zap);
2762 	return (rc);
2763 }
2764 
2765 /*
2766  * List a microzap directory.
2767  */
2768 static int
2769 mzap_list(const mzap_phys_t *mz, size_t size,
2770     int (*callback)(const char *, uint64_t))
2771 {
2772 	const mzap_ent_phys_t *mze;
2773 	int chunks, i, rc;
2774 
2775 	/*
2776 	 * Microzap objects use exactly one block. Read the whole
2777 	 * thing.
2778 	 */
2779 	rc = 0;
2780 	chunks = size / MZAP_ENT_LEN - 1;
2781 	for (i = 0; i < chunks; i++) {
2782 		mze = &mz->mz_chunk[i];
2783 		if (mze->mze_name[0]) {
2784 			rc = callback(mze->mze_name, mze->mze_value);
2785 			if (rc != 0)
2786 				break;
2787 		}
2788 	}
2789 
2790 	return (rc);
2791 }
2792 
2793 /*
2794  * List a fatzap directory.
2795  */
2796 static int
2797 fzap_list(const spa_t *spa, const dnode_phys_t *dnode, zap_phys_t *zh,
2798     int (*callback)(const char *, uint64_t))
2799 {
2800 	int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
2801 	fat_zap_t z;
2802 	uint64_t i;
2803 	int j, rc;
2804 
2805 	if (zh->zap_magic != ZAP_MAGIC)
2806 		return (EIO);
2807 
2808 	z.zap_block_shift = ilog2(bsize);
2809 	z.zap_phys = zh;
2810 
2811 	/*
2812 	 * This assumes that the leaf blocks start at block 1. The
2813 	 * documentation isn't exactly clear on this.
2814 	 */
2815 	zap_leaf_t zl;
2816 	zl.l_bs = z.zap_block_shift;
2817 	zl.l_phys = malloc(bsize);
2818 	if (zl.l_phys == NULL)
2819 		return (ENOMEM);
2820 
2821 	for (i = 0; i < zh->zap_num_leafs; i++) {
2822 		off_t off = ((off_t)(i + 1)) << zl.l_bs;
2823 		char name[256], *p;
2824 		uint64_t value;
2825 
2826 		if (dnode_read(spa, dnode, off, zl.l_phys, bsize)) {
2827 			free(zl.l_phys);
2828 			return (EIO);
2829 		}
2830 
2831 		for (j = 0; j < ZAP_LEAF_NUMCHUNKS(&zl); j++) {
2832 			zap_leaf_chunk_t *zc, *nc;
2833 			int namelen;
2834 
2835 			zc = &ZAP_LEAF_CHUNK(&zl, j);
2836 			if (zc->l_entry.le_type != ZAP_CHUNK_ENTRY)
2837 				continue;
2838 			namelen = zc->l_entry.le_name_numints;
2839 			if (namelen > sizeof(name))
2840 				namelen = sizeof(name);
2841 
2842 			/*
2843 			 * Paste the name back together.
2844 			 */
2845 			nc = &ZAP_LEAF_CHUNK(&zl, zc->l_entry.le_name_chunk);
2846 			p = name;
2847 			while (namelen > 0) {
2848 				int len;
2849 				len = namelen;
2850 				if (len > ZAP_LEAF_ARRAY_BYTES)
2851 					len = ZAP_LEAF_ARRAY_BYTES;
2852 				memcpy(p, nc->l_array.la_array, len);
2853 				p += len;
2854 				namelen -= len;
2855 				nc = &ZAP_LEAF_CHUNK(&zl, nc->l_array.la_next);
2856 			}
2857 
2858 			/*
2859 			 * Assume the first eight bytes of the value are
2860 			 * a uint64_t.
2861 			 */
2862 			value = fzap_leaf_value(&zl, zc);
2863 
2864 			/* printf("%s 0x%jx\n", name, (uintmax_t)value); */
2865 			rc = callback((const char *)name, value);
2866 			if (rc != 0) {
2867 				free(zl.l_phys);
2868 				return (rc);
2869 			}
2870 		}
2871 	}
2872 
2873 	free(zl.l_phys);
2874 	return (0);
2875 }
2876 
2877 static int zfs_printf(const char *name, uint64_t value __unused)
2878 {
2879 
2880 	printf("%s\n", name);
2881 
2882 	return (0);
2883 }
2884 
2885 /*
2886  * List a zap directory.
2887  */
2888 static int
2889 zap_list(const spa_t *spa, const dnode_phys_t *dnode)
2890 {
2891 	zap_phys_t *zap;
2892 	size_t size = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
2893 	int rc;
2894 
2895 	zap = malloc(size);
2896 	if (zap == NULL)
2897 		return (ENOMEM);
2898 
2899 	rc = dnode_read(spa, dnode, 0, zap, size);
2900 	if (rc == 0) {
2901 		if (zap->zap_block_type == ZBT_MICRO)
2902 			rc = mzap_list((const mzap_phys_t *)zap, size,
2903 			    zfs_printf);
2904 		else
2905 			rc = fzap_list(spa, dnode, zap, zfs_printf);
2906 	}
2907 	free(zap);
2908 	return (rc);
2909 }
2910 
2911 static int
2912 objset_get_dnode(const spa_t *spa, const objset_phys_t *os, uint64_t objnum,
2913     dnode_phys_t *dnode)
2914 {
2915 	off_t offset;
2916 
2917 	offset = objnum * sizeof(dnode_phys_t);
2918 	return dnode_read(spa, &os->os_meta_dnode, offset,
2919 		dnode, sizeof(dnode_phys_t));
2920 }
2921 
2922 /*
2923  * Lookup a name in a microzap directory.
2924  */
2925 static int
2926 mzap_rlookup(const mzap_phys_t *mz, size_t size, char *name, uint64_t value)
2927 {
2928 	const mzap_ent_phys_t *mze;
2929 	int chunks, i;
2930 
2931 	/*
2932 	 * Microzap objects use exactly one block. Read the whole
2933 	 * thing.
2934 	 */
2935 	chunks = size / MZAP_ENT_LEN - 1;
2936 	for (i = 0; i < chunks; i++) {
2937 		mze = &mz->mz_chunk[i];
2938 		if (value == mze->mze_value) {
2939 			strcpy(name, mze->mze_name);
2940 			return (0);
2941 		}
2942 	}
2943 
2944 	return (ENOENT);
2945 }
2946 
2947 static void
2948 fzap_name_copy(const zap_leaf_t *zl, const zap_leaf_chunk_t *zc, char *name)
2949 {
2950 	size_t namelen;
2951 	const zap_leaf_chunk_t *nc;
2952 	char *p;
2953 
2954 	namelen = zc->l_entry.le_name_numints;
2955 
2956 	nc = &ZAP_LEAF_CHUNK(zl, zc->l_entry.le_name_chunk);
2957 	p = name;
2958 	while (namelen > 0) {
2959 		size_t len;
2960 		len = namelen;
2961 		if (len > ZAP_LEAF_ARRAY_BYTES)
2962 			len = ZAP_LEAF_ARRAY_BYTES;
2963 		memcpy(p, nc->l_array.la_array, len);
2964 		p += len;
2965 		namelen -= len;
2966 		nc = &ZAP_LEAF_CHUNK(zl, nc->l_array.la_next);
2967 	}
2968 
2969 	*p = '\0';
2970 }
2971 
2972 static int
2973 fzap_rlookup(const spa_t *spa, const dnode_phys_t *dnode, zap_phys_t *zh,
2974     char *name, uint64_t value)
2975 {
2976 	int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
2977 	fat_zap_t z;
2978 	uint64_t i;
2979 	int j, rc;
2980 
2981 	if (zh->zap_magic != ZAP_MAGIC)
2982 		return (EIO);
2983 
2984 	z.zap_block_shift = ilog2(bsize);
2985 	z.zap_phys = zh;
2986 
2987 	/*
2988 	 * This assumes that the leaf blocks start at block 1. The
2989 	 * documentation isn't exactly clear on this.
2990 	 */
2991 	zap_leaf_t zl;
2992 	zl.l_bs = z.zap_block_shift;
2993 	zl.l_phys = malloc(bsize);
2994 	if (zl.l_phys == NULL)
2995 		return (ENOMEM);
2996 
2997 	for (i = 0; i < zh->zap_num_leafs; i++) {
2998 		off_t off = ((off_t)(i + 1)) << zl.l_bs;
2999 
3000 		rc = dnode_read(spa, dnode, off, zl.l_phys, bsize);
3001 		if (rc != 0)
3002 			goto done;
3003 
3004 		for (j = 0; j < ZAP_LEAF_NUMCHUNKS(&zl); j++) {
3005 			zap_leaf_chunk_t *zc;
3006 
3007 			zc = &ZAP_LEAF_CHUNK(&zl, j);
3008 			if (zc->l_entry.le_type != ZAP_CHUNK_ENTRY)
3009 				continue;
3010 			if (zc->l_entry.le_value_intlen != 8 ||
3011 			    zc->l_entry.le_value_numints != 1)
3012 				continue;
3013 
3014 			if (fzap_leaf_value(&zl, zc) == value) {
3015 				fzap_name_copy(&zl, zc, name);
3016 				goto done;
3017 			}
3018 		}
3019 	}
3020 
3021 	rc = ENOENT;
3022 done:
3023 	free(zl.l_phys);
3024 	return (rc);
3025 }
3026 
3027 static int
3028 zap_rlookup(const spa_t *spa, const dnode_phys_t *dnode, char *name,
3029     uint64_t value)
3030 {
3031 	zap_phys_t *zap;
3032 	size_t size = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
3033 	int rc;
3034 
3035 	zap = malloc(size);
3036 	if (zap == NULL)
3037 		return (ENOMEM);
3038 
3039 	rc = dnode_read(spa, dnode, 0, zap, size);
3040 	if (rc == 0) {
3041 		if (zap->zap_block_type == ZBT_MICRO)
3042 			rc = mzap_rlookup((const mzap_phys_t *)zap, size,
3043 			    name, value);
3044 		else
3045 			rc = fzap_rlookup(spa, dnode, zap, name, value);
3046 	}
3047 	free(zap);
3048 	return (rc);
3049 }
3050 
3051 static int
3052 zfs_rlookup(const spa_t *spa, uint64_t objnum, char *result)
3053 {
3054 	char name[256];
3055 	char component[256];
3056 	uint64_t dir_obj, parent_obj, child_dir_zapobj;
3057 	dnode_phys_t child_dir_zap, snapnames_zap, dataset, dir, parent;
3058 	dsl_dir_phys_t *dd;
3059 	dsl_dataset_phys_t *ds;
3060 	char *p;
3061 	int len;
3062 	boolean_t issnap = B_FALSE;
3063 
3064 	p = &name[sizeof(name) - 1];
3065 	*p = '\0';
3066 
3067 	if (objset_get_dnode(spa, spa->spa_mos, objnum, &dataset)) {
3068 		printf("ZFS: can't find dataset %ju\n", (uintmax_t)objnum);
3069 		return (EIO);
3070 	}
3071 	ds = (dsl_dataset_phys_t *)&dataset.dn_bonus;
3072 	dir_obj = ds->ds_dir_obj;
3073 	if (ds->ds_snapnames_zapobj == 0)
3074 		issnap = B_TRUE;
3075 
3076 	for (;;) {
3077 		if (objset_get_dnode(spa, spa->spa_mos, dir_obj, &dir) != 0)
3078 			return (EIO);
3079 		dd = (dsl_dir_phys_t *)&dir.dn_bonus;
3080 
3081 		/* Actual loop condition. */
3082 		parent_obj = dd->dd_parent_obj;
3083 		if (parent_obj == 0)
3084 			break;
3085 
3086 		if (objset_get_dnode(spa, spa->spa_mos, parent_obj,
3087 		    &parent) != 0)
3088 			return (EIO);
3089 		dd = (dsl_dir_phys_t *)&parent.dn_bonus;
3090 		if (issnap == B_TRUE) {
3091 			/*
3092 			 * The dataset we are looking up is a snapshot
3093 			 * the dir_obj is the parent already, we don't want
3094 			 * the grandparent just yet. Reset to the parent.
3095 			 */
3096 			dd = (dsl_dir_phys_t *)&dir.dn_bonus;
3097 			/* Lookup the dataset to get the snapname ZAP */
3098 			if (objset_get_dnode(spa, spa->spa_mos,
3099 			    dd->dd_head_dataset_obj, &dataset))
3100 				return (EIO);
3101 			ds = (dsl_dataset_phys_t *)&dataset.dn_bonus;
3102 			if (objset_get_dnode(spa, spa->spa_mos,
3103 			    ds->ds_snapnames_zapobj, &snapnames_zap) != 0)
3104 				return (EIO);
3105 			/* Get the name of the snapshot */
3106 			if (zap_rlookup(spa, &snapnames_zap, component,
3107 			    objnum) != 0)
3108 				return (EIO);
3109 			len = strlen(component);
3110 			p -= len;
3111 			memcpy(p, component, len);
3112 			--p;
3113 			*p = '@';
3114 			issnap = B_FALSE;
3115 			continue;
3116 		}
3117 
3118 		child_dir_zapobj = dd->dd_child_dir_zapobj;
3119 		if (objset_get_dnode(spa, spa->spa_mos, child_dir_zapobj,
3120 		    &child_dir_zap) != 0)
3121 			return (EIO);
3122 		if (zap_rlookup(spa, &child_dir_zap, component, dir_obj) != 0)
3123 			return (EIO);
3124 
3125 		len = strlen(component);
3126 		p -= len;
3127 		memcpy(p, component, len);
3128 		--p;
3129 		*p = '/';
3130 
3131 		/* Actual loop iteration. */
3132 		dir_obj = parent_obj;
3133 	}
3134 
3135 	if (*p != '\0')
3136 		++p;
3137 	strcpy(result, p);
3138 
3139 	return (0);
3140 }
3141 
3142 static int
3143 zfs_lookup_dataset(const spa_t *spa, const char *name, uint64_t *objnum)
3144 {
3145 	char element[256];
3146 	uint64_t dir_obj, child_dir_zapobj;
3147 	dnode_phys_t child_dir_zap, snapnames_zap, dir, dataset;
3148 	dsl_dir_phys_t *dd;
3149 	dsl_dataset_phys_t *ds;
3150 	const char *p, *q;
3151 	boolean_t issnap = B_FALSE;
3152 
3153 	if (objset_get_dnode(spa, spa->spa_mos,
3154 	    DMU_POOL_DIRECTORY_OBJECT, &dir))
3155 		return (EIO);
3156 	if (zap_lookup(spa, &dir, DMU_POOL_ROOT_DATASET, sizeof (dir_obj),
3157 	    1, &dir_obj))
3158 		return (EIO);
3159 
3160 	p = name;
3161 	for (;;) {
3162 		if (objset_get_dnode(spa, spa->spa_mos, dir_obj, &dir))
3163 			return (EIO);
3164 		dd = (dsl_dir_phys_t *)&dir.dn_bonus;
3165 
3166 		while (*p == '/')
3167 			p++;
3168 		/* Actual loop condition #1. */
3169 		if (*p == '\0')
3170 			break;
3171 
3172 		q = strchr(p, '/');
3173 		if (q) {
3174 			memcpy(element, p, q - p);
3175 			element[q - p] = '\0';
3176 			p = q + 1;
3177 		} else {
3178 			strcpy(element, p);
3179 			p += strlen(p);
3180 		}
3181 
3182 		if (issnap == B_TRUE) {
3183 		        if (objset_get_dnode(spa, spa->spa_mos,
3184 			    dd->dd_head_dataset_obj, &dataset))
3185 		                return (EIO);
3186 			ds = (dsl_dataset_phys_t *)&dataset.dn_bonus;
3187 			if (objset_get_dnode(spa, spa->spa_mos,
3188 			    ds->ds_snapnames_zapobj, &snapnames_zap) != 0)
3189 				return (EIO);
3190 			/* Actual loop condition #2. */
3191 			if (zap_lookup(spa, &snapnames_zap, element,
3192 			    sizeof (dir_obj), 1, &dir_obj) != 0)
3193 				return (ENOENT);
3194 			*objnum = dir_obj;
3195 			return (0);
3196 		} else if ((q = strchr(element, '@')) != NULL) {
3197 			issnap = B_TRUE;
3198 			element[q - element] = '\0';
3199 			p = q + 1;
3200 		}
3201 		child_dir_zapobj = dd->dd_child_dir_zapobj;
3202 		if (objset_get_dnode(spa, spa->spa_mos, child_dir_zapobj,
3203 		    &child_dir_zap) != 0)
3204 			return (EIO);
3205 
3206 		/* Actual loop condition #2. */
3207 		if (zap_lookup(spa, &child_dir_zap, element, sizeof (dir_obj),
3208 		    1, &dir_obj) != 0)
3209 			return (ENOENT);
3210 	}
3211 
3212 	*objnum = dd->dd_head_dataset_obj;
3213 	return (0);
3214 }
3215 
3216 #ifndef BOOT2
3217 static int
3218 zfs_list_dataset(const spa_t *spa, uint64_t objnum/*, int pos, char *entry*/)
3219 {
3220 	uint64_t dir_obj, child_dir_zapobj;
3221 	dnode_phys_t child_dir_zap, dir, dataset;
3222 	dsl_dataset_phys_t *ds;
3223 	dsl_dir_phys_t *dd;
3224 
3225 	if (objset_get_dnode(spa, spa->spa_mos, objnum, &dataset)) {
3226 		printf("ZFS: can't find dataset %ju\n", (uintmax_t)objnum);
3227 		return (EIO);
3228 	}
3229 	ds = (dsl_dataset_phys_t *)&dataset.dn_bonus;
3230 	dir_obj = ds->ds_dir_obj;
3231 
3232 	if (objset_get_dnode(spa, spa->spa_mos, dir_obj, &dir)) {
3233 		printf("ZFS: can't find dirobj %ju\n", (uintmax_t)dir_obj);
3234 		return (EIO);
3235 	}
3236 	dd = (dsl_dir_phys_t *)&dir.dn_bonus;
3237 
3238 	child_dir_zapobj = dd->dd_child_dir_zapobj;
3239 	if (objset_get_dnode(spa, spa->spa_mos, child_dir_zapobj,
3240 	    &child_dir_zap) != 0) {
3241 		printf("ZFS: can't find child zap %ju\n", (uintmax_t)dir_obj);
3242 		return (EIO);
3243 	}
3244 
3245 	return (zap_list(spa, &child_dir_zap) != 0);
3246 }
3247 
3248 int
3249 zfs_callback_dataset(const spa_t *spa, uint64_t objnum,
3250     int (*callback)(const char *, uint64_t))
3251 {
3252 	uint64_t dir_obj, child_dir_zapobj;
3253 	dnode_phys_t child_dir_zap, dir, dataset;
3254 	dsl_dataset_phys_t *ds;
3255 	dsl_dir_phys_t *dd;
3256 	zap_phys_t *zap;
3257 	size_t size;
3258 	int err;
3259 
3260 	err = objset_get_dnode(spa, spa->spa_mos, objnum, &dataset);
3261 	if (err != 0) {
3262 		printf("ZFS: can't find dataset %ju\n", (uintmax_t)objnum);
3263 		return (err);
3264 	}
3265 	ds = (dsl_dataset_phys_t *)&dataset.dn_bonus;
3266 	dir_obj = ds->ds_dir_obj;
3267 
3268 	err = objset_get_dnode(spa, spa->spa_mos, dir_obj, &dir);
3269 	if (err != 0) {
3270 		printf("ZFS: can't find dirobj %ju\n", (uintmax_t)dir_obj);
3271 		return (err);
3272 	}
3273 	dd = (dsl_dir_phys_t *)&dir.dn_bonus;
3274 
3275 	child_dir_zapobj = dd->dd_child_dir_zapobj;
3276 	err = objset_get_dnode(spa, spa->spa_mos, child_dir_zapobj,
3277 	    &child_dir_zap);
3278 	if (err != 0) {
3279 		printf("ZFS: can't find child zap %ju\n", (uintmax_t)dir_obj);
3280 		return (err);
3281 	}
3282 
3283 	size = child_dir_zap.dn_datablkszsec << SPA_MINBLOCKSHIFT;
3284 	zap = malloc(size);
3285 	if (zap != NULL) {
3286 		err = dnode_read(spa, &child_dir_zap, 0, zap, size);
3287 		if (err != 0)
3288 			goto done;
3289 
3290 		if (zap->zap_block_type == ZBT_MICRO)
3291 			err = mzap_list((const mzap_phys_t *)zap, size,
3292 			    callback);
3293 		else
3294 			err = fzap_list(spa, &child_dir_zap, zap, callback);
3295 	} else {
3296 		err = ENOMEM;
3297 	}
3298 done:
3299 	free(zap);
3300 	return (err);
3301 }
3302 #endif
3303 
3304 /*
3305  * Find the object set given the object number of its dataset object
3306  * and return its details in *objset
3307  */
3308 static int
3309 zfs_mount_dataset(const spa_t *spa, uint64_t objnum, objset_phys_t *objset)
3310 {
3311 	dnode_phys_t dataset;
3312 	dsl_dataset_phys_t *ds;
3313 
3314 	if (objset_get_dnode(spa, spa->spa_mos, objnum, &dataset)) {
3315 		printf("ZFS: can't find dataset %ju\n", (uintmax_t)objnum);
3316 		return (EIO);
3317 	}
3318 
3319 	ds = (dsl_dataset_phys_t *)&dataset.dn_bonus;
3320 	if (zio_read(spa, &ds->ds_bp, objset)) {
3321 		printf("ZFS: can't read object set for dataset %ju\n",
3322 		    (uintmax_t)objnum);
3323 		return (EIO);
3324 	}
3325 
3326 	return (0);
3327 }
3328 
3329 /*
3330  * Find the object set pointed to by the BOOTFS property or the root
3331  * dataset if there is none and return its details in *objset
3332  */
3333 static int
3334 zfs_get_root(const spa_t *spa, uint64_t *objid)
3335 {
3336 	dnode_phys_t dir, propdir;
3337 	uint64_t props, bootfs, root;
3338 
3339 	*objid = 0;
3340 
3341 	/*
3342 	 * Start with the MOS directory object.
3343 	 */
3344 	if (objset_get_dnode(spa, spa->spa_mos,
3345 	    DMU_POOL_DIRECTORY_OBJECT, &dir)) {
3346 		printf("ZFS: can't read MOS object directory\n");
3347 		return (EIO);
3348 	}
3349 
3350 	/*
3351 	 * Lookup the pool_props and see if we can find a bootfs.
3352 	 */
3353 	if (zap_lookup(spa, &dir, DMU_POOL_PROPS,
3354 	    sizeof(props), 1, &props) == 0 &&
3355 	    objset_get_dnode(spa, spa->spa_mos, props, &propdir) == 0 &&
3356 	    zap_lookup(spa, &propdir, "bootfs",
3357 	    sizeof(bootfs), 1, &bootfs) == 0 && bootfs != 0) {
3358 		*objid = bootfs;
3359 		return (0);
3360 	}
3361 	/*
3362 	 * Lookup the root dataset directory
3363 	 */
3364 	if (zap_lookup(spa, &dir, DMU_POOL_ROOT_DATASET,
3365 	    sizeof(root), 1, &root) ||
3366 	    objset_get_dnode(spa, spa->spa_mos, root, &dir)) {
3367 		printf("ZFS: can't find root dsl_dir\n");
3368 		return (EIO);
3369 	}
3370 
3371 	/*
3372 	 * Use the information from the dataset directory's bonus buffer
3373 	 * to find the dataset object and from that the object set itself.
3374 	 */
3375 	dsl_dir_phys_t *dd = (dsl_dir_phys_t *)&dir.dn_bonus;
3376 	*objid = dd->dd_head_dataset_obj;
3377 	return (0);
3378 }
3379 
3380 static int
3381 zfs_mount_impl(const spa_t *spa, uint64_t rootobj, struct zfsmount *mount)
3382 {
3383 
3384 	mount->spa = spa;
3385 
3386 	/*
3387 	 * Find the root object set if not explicitly provided
3388 	 */
3389 	if (rootobj == 0 && zfs_get_root(spa, &rootobj)) {
3390 		printf("ZFS: can't find root filesystem\n");
3391 		return (EIO);
3392 	}
3393 
3394 	if (zfs_mount_dataset(spa, rootobj, &mount->objset)) {
3395 		printf("ZFS: can't open root filesystem\n");
3396 		return (EIO);
3397 	}
3398 
3399 	mount->rootobj = rootobj;
3400 
3401 	return (0);
3402 }
3403 
3404 /*
3405  * callback function for feature name checks.
3406  */
3407 static int
3408 check_feature(const char *name, uint64_t value)
3409 {
3410 	int i;
3411 
3412 	if (value == 0)
3413 		return (0);
3414 	if (name[0] == '\0')
3415 		return (0);
3416 
3417 	for (i = 0; features_for_read[i] != NULL; i++) {
3418 		if (strcmp(name, features_for_read[i]) == 0)
3419 			return (0);
3420 	}
3421 	printf("ZFS: unsupported feature: %s\n", name);
3422 	return (EIO);
3423 }
3424 
3425 /*
3426  * Checks whether the MOS features that are active are supported.
3427  */
3428 static int
3429 check_mos_features(const spa_t *spa)
3430 {
3431 	dnode_phys_t dir;
3432 	zap_phys_t *zap;
3433 	uint64_t objnum;
3434 	size_t size;
3435 	int rc;
3436 
3437 	if ((rc = objset_get_dnode(spa, spa->spa_mos, DMU_OT_OBJECT_DIRECTORY,
3438 	    &dir)) != 0)
3439 		return (rc);
3440 	if ((rc = zap_lookup(spa, &dir, DMU_POOL_FEATURES_FOR_READ,
3441 	    sizeof (objnum), 1, &objnum)) != 0) {
3442 		/*
3443 		 * It is older pool without features. As we have already
3444 		 * tested the label, just return without raising the error.
3445 		 */
3446 		return (0);
3447 	}
3448 
3449 	if ((rc = objset_get_dnode(spa, spa->spa_mos, objnum, &dir)) != 0)
3450 		return (rc);
3451 
3452 	if (dir.dn_type != DMU_OTN_ZAP_METADATA)
3453 		return (EIO);
3454 
3455 	size = dir.dn_datablkszsec << SPA_MINBLOCKSHIFT;
3456 	zap = malloc(size);
3457 	if (zap == NULL)
3458 		return (ENOMEM);
3459 
3460 	if (dnode_read(spa, &dir, 0, zap, size)) {
3461 		free(zap);
3462 		return (EIO);
3463 	}
3464 
3465 	if (zap->zap_block_type == ZBT_MICRO)
3466 		rc = mzap_list((const mzap_phys_t *)zap, size, check_feature);
3467 	else
3468 		rc = fzap_list(spa, &dir, zap, check_feature);
3469 
3470 	free(zap);
3471 	return (rc);
3472 }
3473 
3474 static int
3475 load_nvlist(spa_t *spa, uint64_t obj, nvlist_t **value)
3476 {
3477 	dnode_phys_t dir;
3478 	size_t size;
3479 	int rc;
3480 	char *nv;
3481 
3482 	*value = NULL;
3483 	if ((rc = objset_get_dnode(spa, spa->spa_mos, obj, &dir)) != 0)
3484 		return (rc);
3485 	if (dir.dn_type != DMU_OT_PACKED_NVLIST &&
3486 	    dir.dn_bonustype != DMU_OT_PACKED_NVLIST_SIZE) {
3487 		return (EIO);
3488 	}
3489 
3490 	if (dir.dn_bonuslen != sizeof (uint64_t))
3491 		return (EIO);
3492 
3493 	size = *(uint64_t *)DN_BONUS(&dir);
3494 	nv = malloc(size);
3495 	if (nv == NULL)
3496 		return (ENOMEM);
3497 
3498 	rc = dnode_read(spa, &dir, 0, nv, size);
3499 	if (rc != 0) {
3500 		free(nv);
3501 		nv = NULL;
3502 		return (rc);
3503 	}
3504 	*value = nvlist_import(nv, size);
3505 	free(nv);
3506 	return (rc);
3507 }
3508 
3509 static int
3510 zfs_spa_init(spa_t *spa)
3511 {
3512 	struct uberblock checkpoint;
3513 	dnode_phys_t dir;
3514 	uint64_t config_object;
3515 	nvlist_t *nvlist;
3516 	int rc;
3517 
3518 	if (zio_read(spa, &spa->spa_uberblock->ub_rootbp, spa->spa_mos)) {
3519 		printf("ZFS: can't read MOS of pool %s\n", spa->spa_name);
3520 		return (EIO);
3521 	}
3522 	if (spa->spa_mos->os_type != DMU_OST_META) {
3523 		printf("ZFS: corrupted MOS of pool %s\n", spa->spa_name);
3524 		return (EIO);
3525 	}
3526 
3527 	if (objset_get_dnode(spa, &spa->spa_mos_master,
3528 	    DMU_POOL_DIRECTORY_OBJECT, &dir)) {
3529 		printf("ZFS: failed to read pool %s directory object\n",
3530 		    spa->spa_name);
3531 		return (EIO);
3532 	}
3533 	/* this is allowed to fail, older pools do not have salt */
3534 	rc = zap_lookup(spa, &dir, DMU_POOL_CHECKSUM_SALT, 1,
3535 	    sizeof (spa->spa_cksum_salt.zcs_bytes),
3536 	    spa->spa_cksum_salt.zcs_bytes);
3537 
3538 	rc = check_mos_features(spa);
3539 	if (rc != 0) {
3540 		printf("ZFS: pool %s is not supported\n", spa->spa_name);
3541 		return (rc);
3542 	}
3543 
3544 	rc = zap_lookup(spa, &dir, DMU_POOL_CONFIG,
3545 	    sizeof (config_object), 1, &config_object);
3546 	if (rc != 0) {
3547 		printf("ZFS: can not read MOS %s\n", DMU_POOL_CONFIG);
3548 		return (EIO);
3549 	}
3550 	rc = load_nvlist(spa, config_object, &nvlist);
3551 	if (rc != 0)
3552 		return (rc);
3553 
3554 	rc = zap_lookup(spa, &dir, DMU_POOL_ZPOOL_CHECKPOINT,
3555 	    sizeof(uint64_t), sizeof(checkpoint) / sizeof(uint64_t),
3556 	    &checkpoint);
3557 	if (rc == 0 && checkpoint.ub_checkpoint_txg != 0) {
3558 		memcpy(&spa->spa_uberblock_checkpoint, &checkpoint,
3559 		    sizeof(checkpoint));
3560 		if (zio_read(spa, &spa->spa_uberblock_checkpoint.ub_rootbp,
3561 		    &spa->spa_mos_checkpoint)) {
3562 			printf("ZFS: can not read checkpoint data.\n");
3563 			return (EIO);
3564 		}
3565 	}
3566 
3567 	/*
3568 	 * Update vdevs from MOS config. Note, we do skip encoding bytes
3569 	 * here. See also vdev_label_read_config().
3570 	 */
3571 	rc = vdev_init_from_nvlist(spa, nvlist);
3572 	nvlist_destroy(nvlist);
3573 	return (rc);
3574 }
3575 
3576 static int
3577 zfs_dnode_stat(const spa_t *spa, dnode_phys_t *dn, struct stat *sb)
3578 {
3579 
3580 	if (dn->dn_bonustype != DMU_OT_SA) {
3581 		znode_phys_t *zp = (znode_phys_t *)dn->dn_bonus;
3582 
3583 		sb->st_mode = zp->zp_mode;
3584 		sb->st_uid = zp->zp_uid;
3585 		sb->st_gid = zp->zp_gid;
3586 		sb->st_size = zp->zp_size;
3587 	} else {
3588 		sa_hdr_phys_t *sahdrp;
3589 		int hdrsize;
3590 		size_t size = 0;
3591 		void *buf = NULL;
3592 
3593 		if (dn->dn_bonuslen != 0)
3594 			sahdrp = (sa_hdr_phys_t *)DN_BONUS(dn);
3595 		else {
3596 			if ((dn->dn_flags & DNODE_FLAG_SPILL_BLKPTR) != 0) {
3597 				blkptr_t *bp = DN_SPILL_BLKPTR(dn);
3598 				int error;
3599 
3600 				size = BP_GET_LSIZE(bp);
3601 				buf = malloc(size);
3602 				if (buf == NULL)
3603 					error = ENOMEM;
3604 				else
3605 					error = zio_read(spa, bp, buf);
3606 
3607 				if (error != 0) {
3608 					free(buf);
3609 					return (error);
3610 				}
3611 				sahdrp = buf;
3612 			} else {
3613 				return (EIO);
3614 			}
3615 		}
3616 		hdrsize = SA_HDR_SIZE(sahdrp);
3617 		sb->st_mode = *(uint64_t *)((char *)sahdrp + hdrsize +
3618 		    SA_MODE_OFFSET);
3619 		sb->st_uid = *(uint64_t *)((char *)sahdrp + hdrsize +
3620 		    SA_UID_OFFSET);
3621 		sb->st_gid = *(uint64_t *)((char *)sahdrp + hdrsize +
3622 		    SA_GID_OFFSET);
3623 		sb->st_size = *(uint64_t *)((char *)sahdrp + hdrsize +
3624 		    SA_SIZE_OFFSET);
3625 		free(buf);
3626 	}
3627 
3628 	return (0);
3629 }
3630 
3631 static int
3632 zfs_dnode_readlink(const spa_t *spa, dnode_phys_t *dn, char *path, size_t psize)
3633 {
3634 	int rc = 0;
3635 
3636 	if (dn->dn_bonustype == DMU_OT_SA) {
3637 		sa_hdr_phys_t *sahdrp = NULL;
3638 		size_t size = 0;
3639 		void *buf = NULL;
3640 		int hdrsize;
3641 		char *p;
3642 
3643 		if (dn->dn_bonuslen != 0) {
3644 			sahdrp = (sa_hdr_phys_t *)DN_BONUS(dn);
3645 		} else {
3646 			blkptr_t *bp;
3647 
3648 			if ((dn->dn_flags & DNODE_FLAG_SPILL_BLKPTR) == 0)
3649 				return (EIO);
3650 			bp = DN_SPILL_BLKPTR(dn);
3651 
3652 			size = BP_GET_LSIZE(bp);
3653 			buf = malloc(size);
3654 			if (buf == NULL)
3655 				rc = ENOMEM;
3656 			else
3657 				rc = zio_read(spa, bp, buf);
3658 			if (rc != 0) {
3659 				free(buf);
3660 				return (rc);
3661 			}
3662 			sahdrp = buf;
3663 		}
3664 		hdrsize = SA_HDR_SIZE(sahdrp);
3665 		p = (char *)((uintptr_t)sahdrp + hdrsize + SA_SYMLINK_OFFSET);
3666 		memcpy(path, p, psize);
3667 		free(buf);
3668 		return (0);
3669 	}
3670 	/*
3671 	 * Second test is purely to silence bogus compiler
3672 	 * warning about accessing past the end of dn_bonus.
3673 	 */
3674 	if (psize + sizeof(znode_phys_t) <= dn->dn_bonuslen &&
3675 	    sizeof(znode_phys_t) <= sizeof(dn->dn_bonus)) {
3676 		memcpy(path, &dn->dn_bonus[sizeof(znode_phys_t)], psize);
3677 	} else {
3678 		rc = dnode_read(spa, dn, 0, path, psize);
3679 	}
3680 	return (rc);
3681 }
3682 
3683 struct obj_list {
3684 	uint64_t		objnum;
3685 	STAILQ_ENTRY(obj_list)	entry;
3686 };
3687 
3688 /*
3689  * Lookup a file and return its dnode.
3690  */
3691 static int
3692 zfs_lookup(const struct zfsmount *mount, const char *upath, dnode_phys_t *dnode)
3693 {
3694 	int rc;
3695 	uint64_t objnum;
3696 	const spa_t *spa;
3697 	dnode_phys_t dn;
3698 	const char *p, *q;
3699 	char element[256];
3700 	char path[1024];
3701 	int symlinks_followed = 0;
3702 	struct stat sb;
3703 	struct obj_list *entry, *tentry;
3704 	STAILQ_HEAD(, obj_list) on_cache = STAILQ_HEAD_INITIALIZER(on_cache);
3705 
3706 	spa = mount->spa;
3707 	if (mount->objset.os_type != DMU_OST_ZFS) {
3708 		printf("ZFS: unexpected object set type %ju\n",
3709 		    (uintmax_t)mount->objset.os_type);
3710 		return (EIO);
3711 	}
3712 
3713 	if ((entry = malloc(sizeof(struct obj_list))) == NULL)
3714 		return (ENOMEM);
3715 
3716 	/*
3717 	 * Get the root directory dnode.
3718 	 */
3719 	rc = objset_get_dnode(spa, &mount->objset, MASTER_NODE_OBJ, &dn);
3720 	if (rc) {
3721 		free(entry);
3722 		return (rc);
3723 	}
3724 
3725 	rc = zap_lookup(spa, &dn, ZFS_ROOT_OBJ, sizeof(objnum), 1, &objnum);
3726 	if (rc) {
3727 		free(entry);
3728 		return (rc);
3729 	}
3730 	entry->objnum = objnum;
3731 	STAILQ_INSERT_HEAD(&on_cache, entry, entry);
3732 
3733 	rc = objset_get_dnode(spa, &mount->objset, objnum, &dn);
3734 	if (rc != 0)
3735 		goto done;
3736 
3737 	p = upath;
3738 	while (p && *p) {
3739 		rc = objset_get_dnode(spa, &mount->objset, objnum, &dn);
3740 		if (rc != 0)
3741 			goto done;
3742 
3743 		while (*p == '/')
3744 			p++;
3745 		if (*p == '\0')
3746 			break;
3747 		q = p;
3748 		while (*q != '\0' && *q != '/')
3749 			q++;
3750 
3751 		/* skip dot */
3752 		if (p + 1 == q && p[0] == '.') {
3753 			p++;
3754 			continue;
3755 		}
3756 		/* double dot */
3757 		if (p + 2 == q && p[0] == '.' && p[1] == '.') {
3758 			p += 2;
3759 			if (STAILQ_FIRST(&on_cache) ==
3760 			    STAILQ_LAST(&on_cache, obj_list, entry)) {
3761 				rc = ENOENT;
3762 				goto done;
3763 			}
3764 			entry = STAILQ_FIRST(&on_cache);
3765 			STAILQ_REMOVE_HEAD(&on_cache, entry);
3766 			free(entry);
3767 			objnum = (STAILQ_FIRST(&on_cache))->objnum;
3768 			continue;
3769 		}
3770 		if (q - p + 1 > sizeof(element)) {
3771 			rc = ENAMETOOLONG;
3772 			goto done;
3773 		}
3774 		memcpy(element, p, q - p);
3775 		element[q - p] = 0;
3776 		p = q;
3777 
3778 		if ((rc = zfs_dnode_stat(spa, &dn, &sb)) != 0)
3779 			goto done;
3780 		if (!S_ISDIR(sb.st_mode)) {
3781 			rc = ENOTDIR;
3782 			goto done;
3783 		}
3784 
3785 		rc = zap_lookup(spa, &dn, element, sizeof (objnum), 1, &objnum);
3786 		if (rc)
3787 			goto done;
3788 		objnum = ZFS_DIRENT_OBJ(objnum);
3789 
3790 		if ((entry = malloc(sizeof(struct obj_list))) == NULL) {
3791 			rc = ENOMEM;
3792 			goto done;
3793 		}
3794 		entry->objnum = objnum;
3795 		STAILQ_INSERT_HEAD(&on_cache, entry, entry);
3796 		rc = objset_get_dnode(spa, &mount->objset, objnum, &dn);
3797 		if (rc)
3798 			goto done;
3799 
3800 		/*
3801 		 * Check for symlink.
3802 		 */
3803 		rc = zfs_dnode_stat(spa, &dn, &sb);
3804 		if (rc)
3805 			goto done;
3806 		if (S_ISLNK(sb.st_mode)) {
3807 			if (symlinks_followed > 10) {
3808 				rc = EMLINK;
3809 				goto done;
3810 			}
3811 			symlinks_followed++;
3812 
3813 			/*
3814 			 * Read the link value and copy the tail of our
3815 			 * current path onto the end.
3816 			 */
3817 			if (sb.st_size + strlen(p) + 1 > sizeof(path)) {
3818 				rc = ENAMETOOLONG;
3819 				goto done;
3820 			}
3821 			strcpy(&path[sb.st_size], p);
3822 
3823 			rc = zfs_dnode_readlink(spa, &dn, path, sb.st_size);
3824 			if (rc != 0)
3825 				goto done;
3826 
3827 			/*
3828 			 * Restart with the new path, starting either at
3829 			 * the root or at the parent depending whether or
3830 			 * not the link is relative.
3831 			 */
3832 			p = path;
3833 			if (*p == '/') {
3834 				while (STAILQ_FIRST(&on_cache) !=
3835 				    STAILQ_LAST(&on_cache, obj_list, entry)) {
3836 					entry = STAILQ_FIRST(&on_cache);
3837 					STAILQ_REMOVE_HEAD(&on_cache, entry);
3838 					free(entry);
3839 				}
3840 			} else {
3841 				entry = STAILQ_FIRST(&on_cache);
3842 				STAILQ_REMOVE_HEAD(&on_cache, entry);
3843 				free(entry);
3844 			}
3845 			objnum = (STAILQ_FIRST(&on_cache))->objnum;
3846 		}
3847 	}
3848 
3849 	*dnode = dn;
3850 done:
3851 	STAILQ_FOREACH_SAFE(entry, &on_cache, entry, tentry)
3852 		free(entry);
3853 	return (rc);
3854 }
3855 
3856 /*
3857  * Return either a cached copy of the bootenv, or read each of the vdev children
3858  * looking for the bootenv. Cache what's found and return the results. Returns 0
3859  * when benvp is filled in, and some errno when not.
3860  */
3861 static int
3862 zfs_get_bootenv_spa(spa_t *spa, nvlist_t **benvp)
3863 {
3864 	vdev_t *vd;
3865 	nvlist_t *benv = NULL;
3866 
3867 	if (spa->spa_bootenv == NULL) {
3868 		STAILQ_FOREACH(vd, &spa->spa_root_vdev->v_children,
3869 		    v_childlink) {
3870 			benv = vdev_read_bootenv(vd);
3871 
3872 			if (benv != NULL)
3873 				break;
3874 		}
3875 		spa->spa_bootenv = benv;
3876 	}
3877 	benv = spa->spa_bootenv;
3878 
3879 	if (benv == NULL)
3880 		return (ENOENT);
3881 
3882 	*benvp = benv;
3883 	return (0);
3884 }
3885 
3886 /*
3887  * Store nvlist to pool label bootenv area. Also updates cached pointer in spa.
3888  */
3889 static int
3890 zfs_set_bootenv_spa(spa_t *spa, nvlist_t *benv)
3891 {
3892 	vdev_t *vd;
3893 
3894 	STAILQ_FOREACH(vd, &spa->spa_root_vdev->v_children, v_childlink) {
3895 		vdev_write_bootenv(vd, benv);
3896 	}
3897 
3898 	spa->spa_bootenv = benv;
3899 	return (0);
3900 }
3901 
3902 /*
3903  * Get bootonce value by key. The bootonce <key, value> pair is removed from the
3904  * bootenv nvlist and the remaining nvlist is committed back to disk. This process
3905  * the bootonce flag since we've reached the point in the boot that we've 'used'
3906  * the BE. For chained boot scenarios, we may reach this point multiple times (but
3907  * only remove it and return 0 the first time).
3908  */
3909 static int
3910 zfs_get_bootonce_spa(spa_t *spa, const char *key, char *buf, size_t size)
3911 {
3912 	nvlist_t *benv;
3913 	char *result = NULL;
3914 	int result_size, rv;
3915 
3916 	if ((rv = zfs_get_bootenv_spa(spa, &benv)) != 0)
3917 		return (rv);
3918 
3919 	if ((rv = nvlist_find(benv, key, DATA_TYPE_STRING, NULL,
3920 	    &result, &result_size)) == 0) {
3921 		if (result_size == 0) {
3922 			/* ignore empty string */
3923 			rv = ENOENT;
3924 		} else if (buf != NULL) {
3925 			size = MIN((size_t)result_size + 1, size);
3926 			strlcpy(buf, result, size);
3927 		}
3928 		(void)nvlist_remove(benv, key, DATA_TYPE_STRING);
3929 		(void)zfs_set_bootenv_spa(spa, benv);
3930 	}
3931 
3932 	return (rv);
3933 }
3934