xref: /freebsd/stand/libsa/zfs/zfsimpl.c (revision 4e22eafc994140e0c0ddfb5688258ad819e1078e)
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 __FBSDID("$FreeBSD$");
29 
30 /*
31  *	Stand-alone ZFS file reader.
32  */
33 
34 #include <sys/endian.h>
35 #include <sys/stat.h>
36 #include <sys/stdint.h>
37 #include <sys/list.h>
38 #include <machine/_inttypes.h>
39 
40 #include "zfsimpl.h"
41 #include "zfssubr.c"
42 
43 
44 struct zfsmount {
45 	const spa_t	*spa;
46 	objset_phys_t	objset;
47 	uint64_t	rootobj;
48 };
49 static struct zfsmount zfsmount __unused;
50 
51 /*
52  * The indirect_child_t represents the vdev that we will read from, when we
53  * need to read all copies of the data (e.g. for scrub or reconstruction).
54  * For plain (non-mirror) top-level vdevs (i.e. is_vdev is not a mirror),
55  * ic_vdev is the same as is_vdev.  However, for mirror top-level vdevs,
56  * ic_vdev is a child of the mirror.
57  */
58 typedef struct indirect_child {
59 	void *ic_data;
60 	vdev_t *ic_vdev;
61 } indirect_child_t;
62 
63 /*
64  * The indirect_split_t represents one mapped segment of an i/o to the
65  * indirect vdev. For non-split (contiguously-mapped) blocks, there will be
66  * only one indirect_split_t, with is_split_offset==0 and is_size==io_size.
67  * For split blocks, there will be several of these.
68  */
69 typedef struct indirect_split {
70 	list_node_t is_node; /* link on iv_splits */
71 
72 	/*
73 	 * is_split_offset is the offset into the i/o.
74 	 * This is the sum of the previous splits' is_size's.
75 	 */
76 	uint64_t is_split_offset;
77 
78 	vdev_t *is_vdev; /* top-level vdev */
79 	uint64_t is_target_offset; /* offset on is_vdev */
80 	uint64_t is_size;
81 	int is_children; /* number of entries in is_child[] */
82 
83 	/*
84 	 * is_good_child is the child that we are currently using to
85 	 * attempt reconstruction.
86 	 */
87 	int is_good_child;
88 
89 	indirect_child_t is_child[1]; /* variable-length */
90 } indirect_split_t;
91 
92 /*
93  * The indirect_vsd_t is associated with each i/o to the indirect vdev.
94  * It is the "Vdev-Specific Data" in the zio_t's io_vsd.
95  */
96 typedef struct indirect_vsd {
97 	boolean_t iv_split_block;
98 	boolean_t iv_reconstruct;
99 
100 	list_t iv_splits; /* list of indirect_split_t's */
101 } indirect_vsd_t;
102 
103 /*
104  * List of all vdevs, chained through v_alllink.
105  */
106 static vdev_list_t zfs_vdevs;
107 
108 /*
109  * List of ZFS features supported for read
110  */
111 static const char *features_for_read[] = {
112 	"org.illumos:lz4_compress",
113 	"com.delphix:hole_birth",
114 	"com.delphix:extensible_dataset",
115 	"com.delphix:embedded_data",
116 	"org.open-zfs:large_blocks",
117 	"org.illumos:sha512",
118 	"org.illumos:skein",
119 	"org.zfsonlinux:large_dnode",
120 	"com.joyent:multi_vdev_crash_dump",
121 	"com.delphix:spacemap_histogram",
122 	"com.delphix:zpool_checkpoint",
123 	"com.delphix:spacemap_v2",
124 	"com.datto:encryption",
125 	"org.zfsonlinux:allocation_classes",
126 	"com.datto:resilver_defer",
127 	"com.delphix:device_removal",
128 	"com.delphix:obsolete_counts",
129 	"com.intel:allocation_classes",
130 	NULL
131 };
132 
133 /*
134  * List of all pools, chained through spa_link.
135  */
136 static spa_list_t zfs_pools;
137 
138 static const dnode_phys_t *dnode_cache_obj;
139 static uint64_t dnode_cache_bn;
140 static char *dnode_cache_buf;
141 
142 static int zio_read(const spa_t *spa, const blkptr_t *bp, void *buf);
143 static int zfs_get_root(const spa_t *spa, uint64_t *objid);
144 static int zfs_rlookup(const spa_t *spa, uint64_t objnum, char *result);
145 static int zap_lookup(const spa_t *spa, const dnode_phys_t *dnode,
146     const char *name, uint64_t integer_size, uint64_t num_integers,
147     void *value);
148 static int objset_get_dnode(const spa_t *, const objset_phys_t *, uint64_t,
149     dnode_phys_t *);
150 static int dnode_read(const spa_t *, const dnode_phys_t *, off_t, void *,
151     size_t);
152 static int vdev_indirect_read(vdev_t *, const blkptr_t *, void *, off_t,
153     size_t);
154 static int vdev_mirror_read(vdev_t *, const blkptr_t *, void *, off_t, size_t);
155 vdev_indirect_mapping_t *vdev_indirect_mapping_open(spa_t *, objset_phys_t *,
156     uint64_t);
157 vdev_indirect_mapping_entry_phys_t *
158     vdev_indirect_mapping_duplicate_adjacent_entries(vdev_t *, uint64_t,
159     uint64_t, uint64_t *);
160 
161 static void
162 zfs_init(void)
163 {
164 	STAILQ_INIT(&zfs_vdevs);
165 	STAILQ_INIT(&zfs_pools);
166 
167 	dnode_cache_buf = malloc(SPA_MAXBLOCKSIZE);
168 
169 	zfs_init_crc();
170 }
171 
172 static int
173 nvlist_check_features_for_read(nvlist_t *nvl)
174 {
175 	nvlist_t *features = NULL;
176 	nvs_data_t *data;
177 	nvp_header_t *nvp;
178 	nv_string_t *nvp_name;
179 	int rc;
180 
181 	rc = nvlist_find(nvl, ZPOOL_CONFIG_FEATURES_FOR_READ,
182 	    DATA_TYPE_NVLIST, NULL, &features, NULL);
183 	if (rc != 0)
184 		return (rc);
185 
186 	data = (nvs_data_t *)features->nv_data;
187 	nvp = &data->nvl_pair;	/* first pair in nvlist */
188 
189 	while (nvp->encoded_size != 0 && nvp->decoded_size != 0) {
190 		int i, found;
191 
192 		nvp_name = (nv_string_t *)((uintptr_t)nvp + sizeof(*nvp));
193 		found = 0;
194 
195 		for (i = 0; features_for_read[i] != NULL; i++) {
196 			if (memcmp(nvp_name->nv_data, features_for_read[i],
197 			    nvp_name->nv_size) == 0) {
198 				found = 1;
199 				break;
200 			}
201 		}
202 
203 		if (!found) {
204 			printf("ZFS: unsupported feature: %.*s\n",
205 			    nvp_name->nv_size, nvp_name->nv_data);
206 			rc = EIO;
207 		}
208 		nvp = (nvp_header_t *)((uint8_t *)nvp + nvp->encoded_size);
209 	}
210 	nvlist_destroy(features);
211 
212 	return (rc);
213 }
214 
215 static int
216 vdev_read_phys(vdev_t *vdev, const blkptr_t *bp, void *buf,
217     off_t offset, size_t size)
218 {
219 	size_t psize;
220 	int rc;
221 
222 	if (!vdev->v_phys_read)
223 		return (EIO);
224 
225 	if (bp) {
226 		psize = BP_GET_PSIZE(bp);
227 	} else {
228 		psize = size;
229 	}
230 
231 	rc = vdev->v_phys_read(vdev, vdev->v_read_priv, offset, buf, psize);
232 	if (rc == 0) {
233 		if (bp != NULL)
234 			rc = zio_checksum_verify(vdev->v_spa, bp, buf);
235 	}
236 
237 	return (rc);
238 }
239 
240 typedef struct remap_segment {
241 	vdev_t *rs_vd;
242 	uint64_t rs_offset;
243 	uint64_t rs_asize;
244 	uint64_t rs_split_offset;
245 	list_node_t rs_node;
246 } remap_segment_t;
247 
248 static remap_segment_t *
249 rs_alloc(vdev_t *vd, uint64_t offset, uint64_t asize, uint64_t split_offset)
250 {
251 	remap_segment_t *rs = malloc(sizeof (remap_segment_t));
252 
253 	if (rs != NULL) {
254 		rs->rs_vd = vd;
255 		rs->rs_offset = offset;
256 		rs->rs_asize = asize;
257 		rs->rs_split_offset = split_offset;
258 	}
259 
260 	return (rs);
261 }
262 
263 vdev_indirect_mapping_t *
264 vdev_indirect_mapping_open(spa_t *spa, objset_phys_t *os,
265     uint64_t mapping_object)
266 {
267 	vdev_indirect_mapping_t *vim;
268 	vdev_indirect_mapping_phys_t *vim_phys;
269 	int rc;
270 
271 	vim = calloc(1, sizeof (*vim));
272 	if (vim == NULL)
273 		return (NULL);
274 
275 	vim->vim_dn = calloc(1, sizeof (*vim->vim_dn));
276 	if (vim->vim_dn == NULL) {
277 		free(vim);
278 		return (NULL);
279 	}
280 
281 	rc = objset_get_dnode(spa, os, mapping_object, vim->vim_dn);
282 	if (rc != 0) {
283 		free(vim->vim_dn);
284 		free(vim);
285 		return (NULL);
286 	}
287 
288 	vim->vim_spa = spa;
289 	vim->vim_phys = malloc(sizeof (*vim->vim_phys));
290 	if (vim->vim_phys == NULL) {
291 		free(vim->vim_dn);
292 		free(vim);
293 		return (NULL);
294 	}
295 
296 	vim_phys = (vdev_indirect_mapping_phys_t *)DN_BONUS(vim->vim_dn);
297 	*vim->vim_phys = *vim_phys;
298 
299 	vim->vim_objset = os;
300 	vim->vim_object = mapping_object;
301 	vim->vim_entries = NULL;
302 
303 	vim->vim_havecounts =
304 	    (vim->vim_dn->dn_bonuslen > VDEV_INDIRECT_MAPPING_SIZE_V0);
305 
306 	return (vim);
307 }
308 
309 /*
310  * Compare an offset with an indirect mapping entry; there are three
311  * possible scenarios:
312  *
313  *     1. The offset is "less than" the mapping entry; meaning the
314  *        offset is less than the source offset of the mapping entry. In
315  *        this case, there is no overlap between the offset and the
316  *        mapping entry and -1 will be returned.
317  *
318  *     2. The offset is "greater than" the mapping entry; meaning the
319  *        offset is greater than the mapping entry's source offset plus
320  *        the entry's size. In this case, there is no overlap between
321  *        the offset and the mapping entry and 1 will be returned.
322  *
323  *        NOTE: If the offset is actually equal to the entry's offset
324  *        plus size, this is considered to be "greater" than the entry,
325  *        and this case applies (i.e. 1 will be returned). Thus, the
326  *        entry's "range" can be considered to be inclusive at its
327  *        start, but exclusive at its end: e.g. [src, src + size).
328  *
329  *     3. The last case to consider is if the offset actually falls
330  *        within the mapping entry's range. If this is the case, the
331  *        offset is considered to be "equal to" the mapping entry and
332  *        0 will be returned.
333  *
334  *        NOTE: If the offset is equal to the entry's source offset,
335  *        this case applies and 0 will be returned. If the offset is
336  *        equal to the entry's source plus its size, this case does
337  *        *not* apply (see "NOTE" above for scenario 2), and 1 will be
338  *        returned.
339  */
340 static int
341 dva_mapping_overlap_compare(const void *v_key, const void *v_array_elem)
342 {
343 	const uint64_t *key = v_key;
344 	const vdev_indirect_mapping_entry_phys_t *array_elem =
345 	    v_array_elem;
346 	uint64_t src_offset = DVA_MAPPING_GET_SRC_OFFSET(array_elem);
347 
348 	if (*key < src_offset) {
349 		return (-1);
350 	} else if (*key < src_offset + DVA_GET_ASIZE(&array_elem->vimep_dst)) {
351 		return (0);
352 	} else {
353 		return (1);
354 	}
355 }
356 
357 /*
358  * Return array entry.
359  */
360 static vdev_indirect_mapping_entry_phys_t *
361 vdev_indirect_mapping_entry(vdev_indirect_mapping_t *vim, uint64_t index)
362 {
363 	uint64_t size;
364 	off_t offset = 0;
365 	int rc;
366 
367 	if (vim->vim_phys->vimp_num_entries == 0)
368 		return (NULL);
369 
370 	if (vim->vim_entries == NULL) {
371 		uint64_t bsize;
372 
373 		bsize = vim->vim_dn->dn_datablkszsec << SPA_MINBLOCKSHIFT;
374 		size = vim->vim_phys->vimp_num_entries *
375 		    sizeof (*vim->vim_entries);
376 		if (size > bsize) {
377 			size = bsize / sizeof (*vim->vim_entries);
378 			size *= sizeof (*vim->vim_entries);
379 		}
380 		vim->vim_entries = malloc(size);
381 		if (vim->vim_entries == NULL)
382 			return (NULL);
383 		vim->vim_num_entries = size / sizeof (*vim->vim_entries);
384 		offset = index * sizeof (*vim->vim_entries);
385 	}
386 
387 	/* We have data in vim_entries */
388 	if (offset == 0) {
389 		if (index >= vim->vim_entry_offset &&
390 		    index <= vim->vim_entry_offset + vim->vim_num_entries) {
391 			index -= vim->vim_entry_offset;
392 			return (&vim->vim_entries[index]);
393 		}
394 		offset = index * sizeof (*vim->vim_entries);
395 	}
396 
397 	vim->vim_entry_offset = index;
398 	size = vim->vim_num_entries * sizeof (*vim->vim_entries);
399 	rc = dnode_read(vim->vim_spa, vim->vim_dn, offset, vim->vim_entries,
400 	    size);
401 	if (rc != 0) {
402 		/* Read error, invalidate vim_entries. */
403 		free(vim->vim_entries);
404 		vim->vim_entries = NULL;
405 		return (NULL);
406 	}
407 	index -= vim->vim_entry_offset;
408 	return (&vim->vim_entries[index]);
409 }
410 
411 /*
412  * Returns the mapping entry for the given offset.
413  *
414  * It's possible that the given offset will not be in the mapping table
415  * (i.e. no mapping entries contain this offset), in which case, the
416  * return value value depends on the "next_if_missing" parameter.
417  *
418  * If the offset is not found in the table and "next_if_missing" is
419  * B_FALSE, then NULL will always be returned. The behavior is intended
420  * to allow consumers to get the entry corresponding to the offset
421  * parameter, iff the offset overlaps with an entry in the table.
422  *
423  * If the offset is not found in the table and "next_if_missing" is
424  * B_TRUE, then the entry nearest to the given offset will be returned,
425  * such that the entry's source offset is greater than the offset
426  * passed in (i.e. the "next" mapping entry in the table is returned, if
427  * the offset is missing from the table). If there are no entries whose
428  * source offset is greater than the passed in offset, NULL is returned.
429  */
430 static vdev_indirect_mapping_entry_phys_t *
431 vdev_indirect_mapping_entry_for_offset(vdev_indirect_mapping_t *vim,
432     uint64_t offset)
433 {
434 	ASSERT(vim->vim_phys->vimp_num_entries > 0);
435 
436 	vdev_indirect_mapping_entry_phys_t *entry;
437 
438 	uint64_t last = vim->vim_phys->vimp_num_entries - 1;
439 	uint64_t base = 0;
440 
441 	/*
442 	 * We don't define these inside of the while loop because we use
443 	 * their value in the case that offset isn't in the mapping.
444 	 */
445 	uint64_t mid;
446 	int result;
447 
448 	while (last >= base) {
449 		mid = base + ((last - base) >> 1);
450 
451 		entry = vdev_indirect_mapping_entry(vim, mid);
452 		if (entry == NULL)
453 			break;
454 		result = dva_mapping_overlap_compare(&offset, entry);
455 
456 		if (result == 0) {
457 			break;
458 		} else if (result < 0) {
459 			last = mid - 1;
460 		} else {
461 			base = mid + 1;
462 		}
463 	}
464 	return (entry);
465 }
466 
467 /*
468  * Given an indirect vdev and an extent on that vdev, it duplicates the
469  * physical entries of the indirect mapping that correspond to the extent
470  * to a new array and returns a pointer to it. In addition, copied_entries
471  * is populated with the number of mapping entries that were duplicated.
472  *
473  * Finally, since we are doing an allocation, it is up to the caller to
474  * free the array allocated in this function.
475  */
476 vdev_indirect_mapping_entry_phys_t *
477 vdev_indirect_mapping_duplicate_adjacent_entries(vdev_t *vd, uint64_t offset,
478     uint64_t asize, uint64_t *copied_entries)
479 {
480 	vdev_indirect_mapping_entry_phys_t *duplicate_mappings = NULL;
481 	vdev_indirect_mapping_t *vim = vd->v_mapping;
482 	uint64_t entries = 0;
483 
484 	vdev_indirect_mapping_entry_phys_t *first_mapping =
485 	    vdev_indirect_mapping_entry_for_offset(vim, offset);
486 	ASSERT3P(first_mapping, !=, NULL);
487 
488 	vdev_indirect_mapping_entry_phys_t *m = first_mapping;
489 	while (asize > 0) {
490 		uint64_t size = DVA_GET_ASIZE(&m->vimep_dst);
491 		uint64_t inner_offset = offset - DVA_MAPPING_GET_SRC_OFFSET(m);
492 		uint64_t inner_size = MIN(asize, size - inner_offset);
493 
494 		offset += inner_size;
495 		asize -= inner_size;
496 		entries++;
497 		m++;
498 	}
499 
500 	size_t copy_length = entries * sizeof (*first_mapping);
501 	duplicate_mappings = malloc(copy_length);
502 	if (duplicate_mappings != NULL)
503 		bcopy(first_mapping, duplicate_mappings, copy_length);
504 	else
505 		entries = 0;
506 
507 	*copied_entries = entries;
508 
509 	return (duplicate_mappings);
510 }
511 
512 static vdev_t *
513 vdev_lookup_top(spa_t *spa, uint64_t vdev)
514 {
515 	vdev_t *rvd;
516 	vdev_list_t *vlist;
517 
518 	vlist = &spa->spa_root_vdev->v_children;
519 	STAILQ_FOREACH(rvd, vlist, v_childlink)
520 		if (rvd->v_id == vdev)
521 			break;
522 
523 	return (rvd);
524 }
525 
526 /*
527  * This is a callback for vdev_indirect_remap() which allocates an
528  * indirect_split_t for each split segment and adds it to iv_splits.
529  */
530 static void
531 vdev_indirect_gather_splits(uint64_t split_offset, vdev_t *vd, uint64_t offset,
532     uint64_t size, void *arg)
533 {
534 	int n = 1;
535 	zio_t *zio = arg;
536 	indirect_vsd_t *iv = zio->io_vsd;
537 
538 	if (vd->v_read == vdev_indirect_read)
539 		return;
540 
541 	if (vd->v_read == vdev_mirror_read)
542 		n = vd->v_nchildren;
543 
544 	indirect_split_t *is =
545 	    malloc(offsetof(indirect_split_t, is_child[n]));
546 	if (is == NULL) {
547 		zio->io_error = ENOMEM;
548 		return;
549 	}
550 	bzero(is, offsetof(indirect_split_t, is_child[n]));
551 
552 	is->is_children = n;
553 	is->is_size = size;
554 	is->is_split_offset = split_offset;
555 	is->is_target_offset = offset;
556 	is->is_vdev = vd;
557 
558 	/*
559 	 * Note that we only consider multiple copies of the data for
560 	 * *mirror* vdevs.  We don't for "replacing" or "spare" vdevs, even
561 	 * though they use the same ops as mirror, because there's only one
562 	 * "good" copy under the replacing/spare.
563 	 */
564 	if (vd->v_read == vdev_mirror_read) {
565 		int i = 0;
566 		vdev_t *kid;
567 
568 		STAILQ_FOREACH(kid, &vd->v_children, v_childlink) {
569 			is->is_child[i++].ic_vdev = kid;
570 		}
571 	} else {
572 		is->is_child[0].ic_vdev = vd;
573 	}
574 
575 	list_insert_tail(&iv->iv_splits, is);
576 }
577 
578 static void
579 vdev_indirect_remap(vdev_t *vd, uint64_t offset, uint64_t asize, void *arg)
580 {
581 	list_t stack;
582 	spa_t *spa = vd->v_spa;
583 	zio_t *zio = arg;
584 	remap_segment_t *rs;
585 
586 	list_create(&stack, sizeof (remap_segment_t),
587 	    offsetof(remap_segment_t, rs_node));
588 
589 	rs = rs_alloc(vd, offset, asize, 0);
590 	if (rs == NULL) {
591 		printf("vdev_indirect_remap: out of memory.\n");
592 		zio->io_error = ENOMEM;
593 	}
594 	for (; rs != NULL; rs = list_remove_head(&stack)) {
595 		vdev_t *v = rs->rs_vd;
596 		uint64_t num_entries = 0;
597 		/* vdev_indirect_mapping_t *vim = v->v_mapping; */
598 		vdev_indirect_mapping_entry_phys_t *mapping =
599 		    vdev_indirect_mapping_duplicate_adjacent_entries(v,
600 		    rs->rs_offset, rs->rs_asize, &num_entries);
601 
602 		if (num_entries == 0)
603 			zio->io_error = ENOMEM;
604 
605 		for (uint64_t i = 0; i < num_entries; i++) {
606 			vdev_indirect_mapping_entry_phys_t *m = &mapping[i];
607 			uint64_t size = DVA_GET_ASIZE(&m->vimep_dst);
608 			uint64_t dst_offset = DVA_GET_OFFSET(&m->vimep_dst);
609 			uint64_t dst_vdev = DVA_GET_VDEV(&m->vimep_dst);
610 			uint64_t inner_offset = rs->rs_offset -
611 			    DVA_MAPPING_GET_SRC_OFFSET(m);
612 			uint64_t inner_size =
613 			    MIN(rs->rs_asize, size - inner_offset);
614 			vdev_t *dst_v = vdev_lookup_top(spa, dst_vdev);
615 
616 			if (dst_v->v_read == vdev_indirect_read) {
617 				remap_segment_t *o;
618 
619 				o = rs_alloc(dst_v, dst_offset + inner_offset,
620 				    inner_size, rs->rs_split_offset);
621 				if (o == NULL) {
622 					printf("vdev_indirect_remap: "
623 					    "out of memory.\n");
624 					zio->io_error = ENOMEM;
625 					break;
626 				}
627 
628 				list_insert_head(&stack, o);
629 			}
630 			vdev_indirect_gather_splits(rs->rs_split_offset, dst_v,
631 			    dst_offset + inner_offset,
632 			    inner_size, arg);
633 
634 			/*
635 			 * vdev_indirect_gather_splits can have memory
636 			 * allocation error, we can not recover from it.
637 			 */
638 			if (zio->io_error != 0)
639 				break;
640 			rs->rs_offset += inner_size;
641 			rs->rs_asize -= inner_size;
642 			rs->rs_split_offset += inner_size;
643 		}
644 
645 		free(mapping);
646 		free(rs);
647 		if (zio->io_error != 0)
648 			break;
649 	}
650 
651 	list_destroy(&stack);
652 }
653 
654 static void
655 vdev_indirect_map_free(zio_t *zio)
656 {
657 	indirect_vsd_t *iv = zio->io_vsd;
658 	indirect_split_t *is;
659 
660 	while ((is = list_head(&iv->iv_splits)) != NULL) {
661 		for (int c = 0; c < is->is_children; c++) {
662 			indirect_child_t *ic = &is->is_child[c];
663 			free(ic->ic_data);
664 		}
665 		list_remove(&iv->iv_splits, is);
666 		free(is);
667 	}
668 	free(iv);
669 }
670 
671 static int
672 vdev_indirect_read(vdev_t *vdev, const blkptr_t *bp, void *buf,
673     off_t offset, size_t bytes)
674 {
675 	zio_t zio;
676 	spa_t *spa = vdev->v_spa;
677 	indirect_vsd_t *iv;
678 	indirect_split_t *first;
679 	int rc = EIO;
680 
681 	iv = calloc(1, sizeof(*iv));
682 	if (iv == NULL)
683 		return (ENOMEM);
684 
685 	list_create(&iv->iv_splits,
686 	    sizeof (indirect_split_t), offsetof(indirect_split_t, is_node));
687 
688 	bzero(&zio, sizeof(zio));
689 	zio.io_spa = spa;
690 	zio.io_bp = (blkptr_t *)bp;
691 	zio.io_data = buf;
692 	zio.io_size = bytes;
693 	zio.io_offset = offset;
694 	zio.io_vd = vdev;
695 	zio.io_vsd = iv;
696 
697 	if (vdev->v_mapping == NULL) {
698 		vdev_indirect_config_t *vic;
699 
700 		vic = &vdev->vdev_indirect_config;
701 		vdev->v_mapping = vdev_indirect_mapping_open(spa,
702 		    &spa->spa_mos, vic->vic_mapping_object);
703 	}
704 
705 	vdev_indirect_remap(vdev, offset, bytes, &zio);
706 	if (zio.io_error != 0)
707 		return (zio.io_error);
708 
709 	first = list_head(&iv->iv_splits);
710 	if (first->is_size == zio.io_size) {
711 		/*
712 		 * This is not a split block; we are pointing to the entire
713 		 * data, which will checksum the same as the original data.
714 		 * Pass the BP down so that the child i/o can verify the
715 		 * checksum, and try a different location if available
716 		 * (e.g. on a mirror).
717 		 *
718 		 * While this special case could be handled the same as the
719 		 * general (split block) case, doing it this way ensures
720 		 * that the vast majority of blocks on indirect vdevs
721 		 * (which are not split) are handled identically to blocks
722 		 * on non-indirect vdevs.  This allows us to be less strict
723 		 * about performance in the general (but rare) case.
724 		 */
725 		rc = first->is_vdev->v_read(first->is_vdev, zio.io_bp,
726 		    zio.io_data, first->is_target_offset, bytes);
727 	} else {
728 		iv->iv_split_block = B_TRUE;
729 		/*
730 		 * Read one copy of each split segment, from the
731 		 * top-level vdev.  Since we don't know the
732 		 * checksum of each split individually, the child
733 		 * zio can't ensure that we get the right data.
734 		 * E.g. if it's a mirror, it will just read from a
735 		 * random (healthy) leaf vdev.  We have to verify
736 		 * the checksum in vdev_indirect_io_done().
737 		 */
738 		for (indirect_split_t *is = list_head(&iv->iv_splits);
739 		    is != NULL; is = list_next(&iv->iv_splits, is)) {
740 			char *ptr = zio.io_data;
741 
742 			rc = is->is_vdev->v_read(is->is_vdev, zio.io_bp,
743 			    ptr + is->is_split_offset, is->is_target_offset,
744 			    is->is_size);
745 		}
746 		if (zio_checksum_verify(spa, zio.io_bp, zio.io_data))
747 			rc = ECKSUM;
748 		else
749 			rc = 0;
750 	}
751 
752 	vdev_indirect_map_free(&zio);
753 	if (rc == 0)
754 		rc = zio.io_error;
755 
756 	return (rc);
757 }
758 
759 static int
760 vdev_disk_read(vdev_t *vdev, const blkptr_t *bp, void *buf,
761     off_t offset, size_t bytes)
762 {
763 
764 	return (vdev_read_phys(vdev, bp, buf,
765 	    offset + VDEV_LABEL_START_SIZE, bytes));
766 }
767 
768 static int
769 vdev_missing_read(vdev_t *vdev __unused, const blkptr_t *bp __unused,
770     void *buf __unused, off_t offset __unused, size_t bytes __unused)
771 {
772 
773 	return (ENOTSUP);
774 }
775 
776 static int
777 vdev_mirror_read(vdev_t *vdev, const blkptr_t *bp, void *buf,
778     off_t offset, size_t bytes)
779 {
780 	vdev_t *kid;
781 	int rc;
782 
783 	rc = EIO;
784 	STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) {
785 		if (kid->v_state != VDEV_STATE_HEALTHY)
786 			continue;
787 		rc = kid->v_read(kid, bp, buf, offset, bytes);
788 		if (!rc)
789 			return (0);
790 	}
791 
792 	return (rc);
793 }
794 
795 static int
796 vdev_replacing_read(vdev_t *vdev, const blkptr_t *bp, void *buf,
797     off_t offset, size_t bytes)
798 {
799 	vdev_t *kid;
800 
801 	/*
802 	 * Here we should have two kids:
803 	 * First one which is the one we are replacing and we can trust
804 	 * only this one to have valid data, but it might not be present.
805 	 * Second one is that one we are replacing with. It is most likely
806 	 * healthy, but we can't trust it has needed data, so we won't use it.
807 	 */
808 	kid = STAILQ_FIRST(&vdev->v_children);
809 	if (kid == NULL)
810 		return (EIO);
811 	if (kid->v_state != VDEV_STATE_HEALTHY)
812 		return (EIO);
813 	return (kid->v_read(kid, bp, buf, offset, bytes));
814 }
815 
816 static vdev_t *
817 vdev_find(uint64_t guid)
818 {
819 	vdev_t *vdev;
820 
821 	STAILQ_FOREACH(vdev, &zfs_vdevs, v_alllink)
822 		if (vdev->v_guid == guid)
823 			return (vdev);
824 
825 	return (0);
826 }
827 
828 static vdev_t *
829 vdev_create(uint64_t guid, vdev_read_t *_read)
830 {
831 	vdev_t *vdev;
832 	vdev_indirect_config_t *vic;
833 
834 	vdev = calloc(1, sizeof(vdev_t));
835 	if (vdev != NULL) {
836 		STAILQ_INIT(&vdev->v_children);
837 		vdev->v_guid = guid;
838 		vdev->v_read = _read;
839 
840 		/*
841 		 * root vdev has no read function, we use this fact to
842 		 * skip setting up data we do not need for root vdev.
843 		 * We only point root vdev from spa.
844 		 */
845 		if (_read != NULL) {
846 			vic = &vdev->vdev_indirect_config;
847 			vic->vic_prev_indirect_vdev = UINT64_MAX;
848 			STAILQ_INSERT_TAIL(&zfs_vdevs, vdev, v_alllink);
849 		}
850 	}
851 
852 	return (vdev);
853 }
854 
855 static void
856 vdev_set_initial_state(vdev_t *vdev, const nvlist_t *nvlist)
857 {
858 	uint64_t is_offline, is_faulted, is_degraded, is_removed, isnt_present;
859 	uint64_t is_log;
860 
861 	is_offline = is_removed = is_faulted = is_degraded = isnt_present = 0;
862 	is_log = 0;
863 	(void) nvlist_find(nvlist, ZPOOL_CONFIG_OFFLINE, DATA_TYPE_UINT64, NULL,
864 	    &is_offline, NULL);
865 	(void) nvlist_find(nvlist, ZPOOL_CONFIG_REMOVED, DATA_TYPE_UINT64, NULL,
866 	    &is_removed, NULL);
867 	(void) nvlist_find(nvlist, ZPOOL_CONFIG_FAULTED, DATA_TYPE_UINT64, NULL,
868 	    &is_faulted, NULL);
869 	(void) nvlist_find(nvlist, ZPOOL_CONFIG_DEGRADED, DATA_TYPE_UINT64,
870 	    NULL, &is_degraded, NULL);
871 	(void) nvlist_find(nvlist, ZPOOL_CONFIG_NOT_PRESENT, DATA_TYPE_UINT64,
872 	    NULL, &isnt_present, NULL);
873 	(void) nvlist_find(nvlist, ZPOOL_CONFIG_IS_LOG, DATA_TYPE_UINT64, NULL,
874 	    &is_log, NULL);
875 
876 	if (is_offline != 0)
877 		vdev->v_state = VDEV_STATE_OFFLINE;
878 	else if (is_removed != 0)
879 		vdev->v_state = VDEV_STATE_REMOVED;
880 	else if (is_faulted != 0)
881 		vdev->v_state = VDEV_STATE_FAULTED;
882 	else if (is_degraded != 0)
883 		vdev->v_state = VDEV_STATE_DEGRADED;
884 	else if (isnt_present != 0)
885 		vdev->v_state = VDEV_STATE_CANT_OPEN;
886 
887 	vdev->v_islog = is_log != 0;
888 }
889 
890 static int
891 vdev_init(uint64_t guid, const nvlist_t *nvlist, vdev_t **vdevp)
892 {
893 	uint64_t id, ashift, asize, nparity;
894 	const char *path;
895 	const char *type;
896 	int len, pathlen;
897 	char *name;
898 	vdev_t *vdev;
899 
900 	if (nvlist_find(nvlist, ZPOOL_CONFIG_ID, DATA_TYPE_UINT64, NULL, &id,
901 	    NULL) ||
902 	    nvlist_find(nvlist, ZPOOL_CONFIG_TYPE, DATA_TYPE_STRING, NULL,
903 	    &type, &len)) {
904 		return (ENOENT);
905 	}
906 
907 	if (memcmp(type, VDEV_TYPE_MIRROR, len) != 0 &&
908 	    memcmp(type, VDEV_TYPE_DISK, len) != 0 &&
909 #ifdef ZFS_TEST
910 	    memcmp(type, VDEV_TYPE_FILE, len) != 0 &&
911 #endif
912 	    memcmp(type, VDEV_TYPE_RAIDZ, len) != 0 &&
913 	    memcmp(type, VDEV_TYPE_INDIRECT, len) != 0 &&
914 	    memcmp(type, VDEV_TYPE_REPLACING, len) != 0 &&
915 	    memcmp(type, VDEV_TYPE_HOLE, len) != 0) {
916 		printf("ZFS: can only boot from disk, mirror, raidz1, "
917 		    "raidz2 and raidz3 vdevs, got: %.*s\n", len, type);
918 		return (EIO);
919 	}
920 
921 	if (memcmp(type, VDEV_TYPE_MIRROR, len) == 0)
922 		vdev = vdev_create(guid, vdev_mirror_read);
923 	else if (memcmp(type, VDEV_TYPE_RAIDZ, len) == 0)
924 		vdev = vdev_create(guid, vdev_raidz_read);
925 	else if (memcmp(type, VDEV_TYPE_REPLACING, len) == 0)
926 		vdev = vdev_create(guid, vdev_replacing_read);
927 	else if (memcmp(type, VDEV_TYPE_INDIRECT, len) == 0) {
928 		vdev_indirect_config_t *vic;
929 
930 		vdev = vdev_create(guid, vdev_indirect_read);
931 		if (vdev != NULL) {
932 			vdev->v_state = VDEV_STATE_HEALTHY;
933 			vic = &vdev->vdev_indirect_config;
934 
935 			nvlist_find(nvlist,
936 			    ZPOOL_CONFIG_INDIRECT_OBJECT,
937 			    DATA_TYPE_UINT64,
938 			    NULL, &vic->vic_mapping_object, NULL);
939 			nvlist_find(nvlist,
940 			    ZPOOL_CONFIG_INDIRECT_BIRTHS,
941 			    DATA_TYPE_UINT64,
942 			    NULL, &vic->vic_births_object, NULL);
943 			nvlist_find(nvlist,
944 			    ZPOOL_CONFIG_PREV_INDIRECT_VDEV,
945 			    DATA_TYPE_UINT64,
946 			    NULL, &vic->vic_prev_indirect_vdev, NULL);
947 		}
948 	} else if (memcmp(type, VDEV_TYPE_HOLE, len) == 0) {
949 		vdev = vdev_create(guid, vdev_missing_read);
950 	} else {
951 		vdev = vdev_create(guid, vdev_disk_read);
952 	}
953 
954 	if (vdev == NULL)
955 		return (ENOMEM);
956 
957 	vdev_set_initial_state(vdev, nvlist);
958 	vdev->v_id = id;
959 	if (nvlist_find(nvlist, ZPOOL_CONFIG_ASHIFT,
960 	    DATA_TYPE_UINT64, NULL, &ashift, NULL) == 0)
961 		vdev->v_ashift = ashift;
962 
963 	if (nvlist_find(nvlist, ZPOOL_CONFIG_ASIZE,
964 	    DATA_TYPE_UINT64, NULL, &asize, NULL) == 0) {
965 		vdev->v_psize = asize +
966 		    VDEV_LABEL_START_SIZE + VDEV_LABEL_END_SIZE;
967 	}
968 
969 	if (nvlist_find(nvlist, ZPOOL_CONFIG_NPARITY,
970 	    DATA_TYPE_UINT64, NULL, &nparity, NULL) == 0)
971 		vdev->v_nparity = nparity;
972 
973 	if (nvlist_find(nvlist, ZPOOL_CONFIG_PATH,
974 	    DATA_TYPE_STRING, NULL, &path, &pathlen) == 0) {
975 		char prefix[] = "/dev/";
976 
977 		len = strlen(prefix);
978 		if (len < pathlen && memcmp(path, prefix, len) == 0) {
979 			path += len;
980 			pathlen -= len;
981 		}
982 		name = malloc(pathlen + 1);
983 		bcopy(path, name, pathlen);
984 		name[pathlen] = '\0';
985 		vdev->v_name = name;
986 	} else {
987 		name = NULL;
988 		if (memcmp(type, VDEV_TYPE_RAIDZ, len) == 0) {
989 			if (vdev->v_nparity < 1 ||
990 			    vdev->v_nparity > 3) {
991 				printf("ZFS: invalid raidz parity: %d\n",
992 				    vdev->v_nparity);
993 				return (EIO);
994 			}
995 			(void) asprintf(&name, "%.*s%d-%" PRIu64, len, type,
996 			    vdev->v_nparity, id);
997 		} else {
998 			(void) asprintf(&name, "%.*s-%" PRIu64, len, type, id);
999 		}
1000 		vdev->v_name = name;
1001 	}
1002 	*vdevp = vdev;
1003 	return (0);
1004 }
1005 
1006 /*
1007  * Find slot for vdev. We return either NULL to signal to use
1008  * STAILQ_INSERT_HEAD, or we return link element to be used with
1009  * STAILQ_INSERT_AFTER.
1010  */
1011 static vdev_t *
1012 vdev_find_previous(vdev_t *top_vdev, vdev_t *vdev)
1013 {
1014 	vdev_t *v, *previous;
1015 
1016 	if (STAILQ_EMPTY(&top_vdev->v_children))
1017 		return (NULL);
1018 
1019 	previous = NULL;
1020 	STAILQ_FOREACH(v, &top_vdev->v_children, v_childlink) {
1021 		if (v->v_id > vdev->v_id)
1022 			return (previous);
1023 
1024 		if (v->v_id == vdev->v_id)
1025 			return (v);
1026 
1027 		if (v->v_id < vdev->v_id)
1028 			previous = v;
1029 	}
1030 	return (previous);
1031 }
1032 
1033 static size_t
1034 vdev_child_count(vdev_t *vdev)
1035 {
1036 	vdev_t *v;
1037 	size_t count;
1038 
1039 	count = 0;
1040 	STAILQ_FOREACH(v, &vdev->v_children, v_childlink) {
1041 		count++;
1042 	}
1043 	return (count);
1044 }
1045 
1046 /*
1047  * Insert vdev into top_vdev children list. List is ordered by v_id.
1048  */
1049 static void
1050 vdev_insert(vdev_t *top_vdev, vdev_t *vdev)
1051 {
1052 	vdev_t *previous;
1053 	size_t count;
1054 
1055 	/*
1056 	 * The top level vdev can appear in random order, depending how
1057 	 * the firmware is presenting the disk devices.
1058 	 * However, we will insert vdev to create list ordered by v_id,
1059 	 * so we can use either STAILQ_INSERT_HEAD or STAILQ_INSERT_AFTER
1060 	 * as STAILQ does not have insert before.
1061 	 */
1062 	previous = vdev_find_previous(top_vdev, vdev);
1063 
1064 	if (previous == NULL) {
1065 		STAILQ_INSERT_HEAD(&top_vdev->v_children, vdev, v_childlink);
1066 	} else if (previous->v_id == vdev->v_id) {
1067 		/*
1068 		 * This vdev was configured from label config,
1069 		 * do not insert duplicate.
1070 		 */
1071 		return;
1072 	} else {
1073 		STAILQ_INSERT_AFTER(&top_vdev->v_children, previous, vdev,
1074 		    v_childlink);
1075 	}
1076 
1077 	count = vdev_child_count(top_vdev);
1078 	if (top_vdev->v_nchildren < count)
1079 		top_vdev->v_nchildren = count;
1080 }
1081 
1082 static int
1083 vdev_from_nvlist(spa_t *spa, uint64_t top_guid, const nvlist_t *nvlist)
1084 {
1085 	vdev_t *top_vdev, *vdev;
1086 	nvlist_t *kids = NULL;
1087 	int rc, nkids;
1088 
1089 	/* Get top vdev. */
1090 	top_vdev = vdev_find(top_guid);
1091 	if (top_vdev == NULL) {
1092 		rc = vdev_init(top_guid, nvlist, &top_vdev);
1093 		if (rc != 0)
1094 			return (rc);
1095 		top_vdev->v_spa = spa;
1096 		top_vdev->v_top = top_vdev;
1097 		vdev_insert(spa->spa_root_vdev, top_vdev);
1098 	}
1099 
1100 	/* Add children if there are any. */
1101 	rc = nvlist_find(nvlist, ZPOOL_CONFIG_CHILDREN, DATA_TYPE_NVLIST_ARRAY,
1102 	    &nkids, &kids, NULL);
1103 	if (rc == 0) {
1104 		for (int i = 0; i < nkids; i++) {
1105 			uint64_t guid;
1106 
1107 			rc = nvlist_find(kids, ZPOOL_CONFIG_GUID,
1108 			    DATA_TYPE_UINT64, NULL, &guid, NULL);
1109 			if (rc != 0) {
1110 				nvlist_destroy(kids);
1111 				return (rc);
1112 			}
1113 			rc = vdev_init(guid, kids, &vdev);
1114 			if (rc != 0)
1115 				return (rc);
1116 
1117 			vdev->v_spa = spa;
1118 			vdev->v_top = top_vdev;
1119 			vdev_insert(top_vdev, vdev);
1120 
1121 			rc = nvlist_next(kids);
1122 		}
1123 	} else {
1124 		/*
1125 		 * When there are no children, nvlist_find() does return
1126 		 * error, reset it because leaf devices have no children.
1127 		 */
1128 		rc = 0;
1129 	}
1130 	nvlist_destroy(kids);
1131 
1132 	return (rc);
1133 }
1134 
1135 static int
1136 vdev_init_from_label(spa_t *spa, const nvlist_t *nvlist)
1137 {
1138 	uint64_t pool_guid, top_guid;
1139 	nvlist_t *vdevs;
1140 	int rc;
1141 
1142 	if (nvlist_find(nvlist, ZPOOL_CONFIG_POOL_GUID, DATA_TYPE_UINT64,
1143 	    NULL, &pool_guid, NULL) ||
1144 	    nvlist_find(nvlist, ZPOOL_CONFIG_TOP_GUID, DATA_TYPE_UINT64,
1145 	    NULL, &top_guid, NULL) ||
1146 	    nvlist_find(nvlist, ZPOOL_CONFIG_VDEV_TREE, DATA_TYPE_NVLIST,
1147 	    NULL, &vdevs, NULL)) {
1148 		printf("ZFS: can't find vdev details\n");
1149 		return (ENOENT);
1150 	}
1151 
1152 	rc = vdev_from_nvlist(spa, top_guid, vdevs);
1153 	nvlist_destroy(vdevs);
1154 	return (rc);
1155 }
1156 
1157 static void
1158 vdev_set_state(vdev_t *vdev)
1159 {
1160 	vdev_t *kid;
1161 	int good_kids;
1162 	int bad_kids;
1163 
1164 	STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) {
1165 		vdev_set_state(kid);
1166 	}
1167 
1168 	/*
1169 	 * A mirror or raidz is healthy if all its kids are healthy. A
1170 	 * mirror is degraded if any of its kids is healthy; a raidz
1171 	 * is degraded if at most nparity kids are offline.
1172 	 */
1173 	if (STAILQ_FIRST(&vdev->v_children)) {
1174 		good_kids = 0;
1175 		bad_kids = 0;
1176 		STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) {
1177 			if (kid->v_state == VDEV_STATE_HEALTHY)
1178 				good_kids++;
1179 			else
1180 				bad_kids++;
1181 		}
1182 		if (bad_kids == 0) {
1183 			vdev->v_state = VDEV_STATE_HEALTHY;
1184 		} else {
1185 			if (vdev->v_read == vdev_mirror_read) {
1186 				if (good_kids) {
1187 					vdev->v_state = VDEV_STATE_DEGRADED;
1188 				} else {
1189 					vdev->v_state = VDEV_STATE_OFFLINE;
1190 				}
1191 			} else if (vdev->v_read == vdev_raidz_read) {
1192 				if (bad_kids > vdev->v_nparity) {
1193 					vdev->v_state = VDEV_STATE_OFFLINE;
1194 				} else {
1195 					vdev->v_state = VDEV_STATE_DEGRADED;
1196 				}
1197 			}
1198 		}
1199 	}
1200 }
1201 
1202 static int
1203 vdev_update_from_nvlist(uint64_t top_guid, const nvlist_t *nvlist)
1204 {
1205 	vdev_t *vdev;
1206 	nvlist_t *kids = NULL;
1207 	int rc, nkids;
1208 
1209 	/* Update top vdev. */
1210 	vdev = vdev_find(top_guid);
1211 	if (vdev != NULL)
1212 		vdev_set_initial_state(vdev, nvlist);
1213 
1214 	/* Update children if there are any. */
1215 	rc = nvlist_find(nvlist, ZPOOL_CONFIG_CHILDREN, DATA_TYPE_NVLIST_ARRAY,
1216 	    &nkids, &kids, NULL);
1217 	if (rc == 0) {
1218 		for (int i = 0; i < nkids; i++) {
1219 			uint64_t guid;
1220 
1221 			rc = nvlist_find(kids, ZPOOL_CONFIG_GUID,
1222 			    DATA_TYPE_UINT64, NULL, &guid, NULL);
1223 			if (rc != 0)
1224 				break;
1225 
1226 			vdev = vdev_find(guid);
1227 			if (vdev != NULL)
1228 				vdev_set_initial_state(vdev, kids);
1229 
1230 			rc = nvlist_next(kids);
1231 		}
1232 	} else {
1233 		rc = 0;
1234 	}
1235 	nvlist_destroy(kids);
1236 
1237 	return (rc);
1238 }
1239 
1240 static int
1241 vdev_init_from_nvlist(spa_t *spa, const nvlist_t *nvlist)
1242 {
1243 	uint64_t pool_guid, vdev_children;
1244 	nvlist_t *vdevs = NULL, *kids = NULL;
1245 	int rc, nkids;
1246 
1247 	if (nvlist_find(nvlist, ZPOOL_CONFIG_POOL_GUID, DATA_TYPE_UINT64,
1248 	    NULL, &pool_guid, NULL) ||
1249 	    nvlist_find(nvlist, ZPOOL_CONFIG_VDEV_CHILDREN, DATA_TYPE_UINT64,
1250 	    NULL, &vdev_children, NULL) ||
1251 	    nvlist_find(nvlist, ZPOOL_CONFIG_VDEV_TREE, DATA_TYPE_NVLIST,
1252 	    NULL, &vdevs, NULL)) {
1253 		printf("ZFS: can't find vdev details\n");
1254 		return (ENOENT);
1255 	}
1256 
1257 	/* Wrong guid?! */
1258 	if (spa->spa_guid != pool_guid) {
1259 		nvlist_destroy(vdevs);
1260 		return (EINVAL);
1261 	}
1262 
1263 	spa->spa_root_vdev->v_nchildren = vdev_children;
1264 
1265 	rc = nvlist_find(vdevs, ZPOOL_CONFIG_CHILDREN, DATA_TYPE_NVLIST_ARRAY,
1266 	    &nkids, &kids, NULL);
1267 	nvlist_destroy(vdevs);
1268 
1269 	/*
1270 	 * MOS config has at least one child for root vdev.
1271 	 */
1272 	if (rc != 0)
1273 		return (rc);
1274 
1275 	for (int i = 0; i < nkids; i++) {
1276 		uint64_t guid;
1277 		vdev_t *vdev;
1278 
1279 		rc = nvlist_find(kids, ZPOOL_CONFIG_GUID, DATA_TYPE_UINT64,
1280 		    NULL, &guid, NULL);
1281 		if (rc != 0)
1282 			break;
1283 		vdev = vdev_find(guid);
1284 		/*
1285 		 * Top level vdev is missing, create it.
1286 		 */
1287 		if (vdev == NULL)
1288 			rc = vdev_from_nvlist(spa, guid, kids);
1289 		else
1290 			rc = vdev_update_from_nvlist(guid, kids);
1291 		if (rc != 0)
1292 			break;
1293 		nvlist_next(kids);
1294 	}
1295 	nvlist_destroy(kids);
1296 
1297 	/*
1298 	 * Re-evaluate top-level vdev state.
1299 	 */
1300 	vdev_set_state(spa->spa_root_vdev);
1301 
1302 	return (rc);
1303 }
1304 
1305 static spa_t *
1306 spa_find_by_guid(uint64_t guid)
1307 {
1308 	spa_t *spa;
1309 
1310 	STAILQ_FOREACH(spa, &zfs_pools, spa_link)
1311 		if (spa->spa_guid == guid)
1312 			return (spa);
1313 
1314 	return (NULL);
1315 }
1316 
1317 static spa_t *
1318 spa_find_by_name(const char *name)
1319 {
1320 	spa_t *spa;
1321 
1322 	STAILQ_FOREACH(spa, &zfs_pools, spa_link)
1323 		if (strcmp(spa->spa_name, name) == 0)
1324 			return (spa);
1325 
1326 	return (NULL);
1327 }
1328 
1329 #ifdef BOOT2
1330 static spa_t *
1331 spa_get_primary(void)
1332 {
1333 
1334 	return (STAILQ_FIRST(&zfs_pools));
1335 }
1336 
1337 static vdev_t *
1338 spa_get_primary_vdev(const spa_t *spa)
1339 {
1340 	vdev_t *vdev;
1341 	vdev_t *kid;
1342 
1343 	if (spa == NULL)
1344 		spa = spa_get_primary();
1345 	if (spa == NULL)
1346 		return (NULL);
1347 	vdev = spa->spa_root_vdev;
1348 	if (vdev == NULL)
1349 		return (NULL);
1350 	for (kid = STAILQ_FIRST(&vdev->v_children); kid != NULL;
1351 	    kid = STAILQ_FIRST(&vdev->v_children))
1352 		vdev = kid;
1353 	return (vdev);
1354 }
1355 #endif
1356 
1357 static spa_t *
1358 spa_create(uint64_t guid, const char *name)
1359 {
1360 	spa_t *spa;
1361 
1362 	if ((spa = calloc(1, sizeof(spa_t))) == NULL)
1363 		return (NULL);
1364 	if ((spa->spa_name = strdup(name)) == NULL) {
1365 		free(spa);
1366 		return (NULL);
1367 	}
1368 	spa->spa_guid = guid;
1369 	spa->spa_root_vdev = vdev_create(guid, NULL);
1370 	if (spa->spa_root_vdev == NULL) {
1371 		free(spa->spa_name);
1372 		free(spa);
1373 		return (NULL);
1374 	}
1375 	spa->spa_root_vdev->v_name = strdup("root");
1376 	STAILQ_INSERT_TAIL(&zfs_pools, spa, spa_link);
1377 
1378 	return (spa);
1379 }
1380 
1381 static const char *
1382 state_name(vdev_state_t state)
1383 {
1384 	static const char *names[] = {
1385 		"UNKNOWN",
1386 		"CLOSED",
1387 		"OFFLINE",
1388 		"REMOVED",
1389 		"CANT_OPEN",
1390 		"FAULTED",
1391 		"DEGRADED",
1392 		"ONLINE"
1393 	};
1394 	return (names[state]);
1395 }
1396 
1397 #ifdef BOOT2
1398 
1399 #define pager_printf printf
1400 
1401 #else
1402 
1403 static int
1404 pager_printf(const char *fmt, ...)
1405 {
1406 	char line[80];
1407 	va_list args;
1408 
1409 	va_start(args, fmt);
1410 	vsnprintf(line, sizeof(line), fmt, args);
1411 	va_end(args);
1412 	return (pager_output(line));
1413 }
1414 
1415 #endif
1416 
1417 #define	STATUS_FORMAT	"        %s %s\n"
1418 
1419 static int
1420 print_state(int indent, const char *name, vdev_state_t state)
1421 {
1422 	int i;
1423 	char buf[512];
1424 
1425 	buf[0] = 0;
1426 	for (i = 0; i < indent; i++)
1427 		strcat(buf, "  ");
1428 	strcat(buf, name);
1429 	return (pager_printf(STATUS_FORMAT, buf, state_name(state)));
1430 }
1431 
1432 static int
1433 vdev_status(vdev_t *vdev, int indent)
1434 {
1435 	vdev_t *kid;
1436 	int ret;
1437 
1438 	if (vdev->v_islog) {
1439 		(void) pager_output("        logs\n");
1440 		indent++;
1441 	}
1442 
1443 	ret = print_state(indent, vdev->v_name, vdev->v_state);
1444 	if (ret != 0)
1445 		return (ret);
1446 
1447 	STAILQ_FOREACH(kid, &vdev->v_children, v_childlink) {
1448 		ret = vdev_status(kid, indent + 1);
1449 		if (ret != 0)
1450 			return (ret);
1451 	}
1452 	return (ret);
1453 }
1454 
1455 static int
1456 spa_status(spa_t *spa)
1457 {
1458 	static char bootfs[ZFS_MAXNAMELEN];
1459 	uint64_t rootid;
1460 	vdev_list_t *vlist;
1461 	vdev_t *vdev;
1462 	int good_kids, bad_kids, degraded_kids, ret;
1463 	vdev_state_t state;
1464 
1465 	ret = pager_printf("  pool: %s\n", spa->spa_name);
1466 	if (ret != 0)
1467 		return (ret);
1468 
1469 	if (zfs_get_root(spa, &rootid) == 0 &&
1470 	    zfs_rlookup(spa, rootid, bootfs) == 0) {
1471 		if (bootfs[0] == '\0')
1472 			ret = pager_printf("bootfs: %s\n", spa->spa_name);
1473 		else
1474 			ret = pager_printf("bootfs: %s/%s\n", spa->spa_name,
1475 			    bootfs);
1476 		if (ret != 0)
1477 			return (ret);
1478 	}
1479 	ret = pager_printf("config:\n\n");
1480 	if (ret != 0)
1481 		return (ret);
1482 	ret = pager_printf(STATUS_FORMAT, "NAME", "STATE");
1483 	if (ret != 0)
1484 		return (ret);
1485 
1486 	good_kids = 0;
1487 	degraded_kids = 0;
1488 	bad_kids = 0;
1489 	vlist = &spa->spa_root_vdev->v_children;
1490 	STAILQ_FOREACH(vdev, vlist, v_childlink) {
1491 		if (vdev->v_state == VDEV_STATE_HEALTHY)
1492 			good_kids++;
1493 		else if (vdev->v_state == VDEV_STATE_DEGRADED)
1494 			degraded_kids++;
1495 		else
1496 			bad_kids++;
1497 	}
1498 
1499 	state = VDEV_STATE_CLOSED;
1500 	if (good_kids > 0 && (degraded_kids + bad_kids) == 0)
1501 		state = VDEV_STATE_HEALTHY;
1502 	else if ((good_kids + degraded_kids) > 0)
1503 		state = VDEV_STATE_DEGRADED;
1504 
1505 	ret = print_state(0, spa->spa_name, state);
1506 	if (ret != 0)
1507 		return (ret);
1508 
1509 	STAILQ_FOREACH(vdev, vlist, v_childlink) {
1510 		ret = vdev_status(vdev, 1);
1511 		if (ret != 0)
1512 			return (ret);
1513 	}
1514 	return (ret);
1515 }
1516 
1517 static int
1518 spa_all_status(void)
1519 {
1520 	spa_t *spa;
1521 	int first = 1, ret = 0;
1522 
1523 	STAILQ_FOREACH(spa, &zfs_pools, spa_link) {
1524 		if (!first) {
1525 			ret = pager_printf("\n");
1526 			if (ret != 0)
1527 				return (ret);
1528 		}
1529 		first = 0;
1530 		ret = spa_status(spa);
1531 		if (ret != 0)
1532 			return (ret);
1533 	}
1534 	return (ret);
1535 }
1536 
1537 static uint64_t
1538 vdev_label_offset(uint64_t psize, int l, uint64_t offset)
1539 {
1540 	uint64_t label_offset;
1541 
1542 	if (l < VDEV_LABELS / 2)
1543 		label_offset = 0;
1544 	else
1545 		label_offset = psize - VDEV_LABELS * sizeof (vdev_label_t);
1546 
1547 	return (offset + l * sizeof (vdev_label_t) + label_offset);
1548 }
1549 
1550 static int
1551 vdev_uberblock_compare(const uberblock_t *ub1, const uberblock_t *ub2)
1552 {
1553 	unsigned int seq1 = 0;
1554 	unsigned int seq2 = 0;
1555 	int cmp = AVL_CMP(ub1->ub_txg, ub2->ub_txg);
1556 
1557 	if (cmp != 0)
1558 		return (cmp);
1559 
1560 	cmp = AVL_CMP(ub1->ub_timestamp, ub2->ub_timestamp);
1561 	if (cmp != 0)
1562 		return (cmp);
1563 
1564 	if (MMP_VALID(ub1) && MMP_SEQ_VALID(ub1))
1565 		seq1 = MMP_SEQ(ub1);
1566 
1567 	if (MMP_VALID(ub2) && MMP_SEQ_VALID(ub2))
1568 		seq2 = MMP_SEQ(ub2);
1569 
1570 	return (AVL_CMP(seq1, seq2));
1571 }
1572 
1573 static int
1574 uberblock_verify(uberblock_t *ub)
1575 {
1576 	if (ub->ub_magic == BSWAP_64((uint64_t)UBERBLOCK_MAGIC)) {
1577 		byteswap_uint64_array(ub, sizeof (uberblock_t));
1578 	}
1579 
1580 	if (ub->ub_magic != UBERBLOCK_MAGIC ||
1581 	    !SPA_VERSION_IS_SUPPORTED(ub->ub_version))
1582 		return (EINVAL);
1583 
1584 	return (0);
1585 }
1586 
1587 static int
1588 vdev_label_read(vdev_t *vd, int l, void *buf, uint64_t offset,
1589     size_t size)
1590 {
1591 	blkptr_t bp;
1592 	off_t off;
1593 
1594 	off = vdev_label_offset(vd->v_psize, l, offset);
1595 
1596 	BP_ZERO(&bp);
1597 	BP_SET_LSIZE(&bp, size);
1598 	BP_SET_PSIZE(&bp, size);
1599 	BP_SET_CHECKSUM(&bp, ZIO_CHECKSUM_LABEL);
1600 	BP_SET_COMPRESS(&bp, ZIO_COMPRESS_OFF);
1601 	DVA_SET_OFFSET(BP_IDENTITY(&bp), off);
1602 	ZIO_SET_CHECKSUM(&bp.blk_cksum, off, 0, 0, 0);
1603 
1604 	return (vdev_read_phys(vd, &bp, buf, off, size));
1605 }
1606 
1607 static nvlist_t *
1608 vdev_label_read_config(vdev_t *vd, uint64_t txg)
1609 {
1610 	vdev_phys_t *label;
1611 	uint64_t best_txg = 0;
1612 	uint64_t label_txg = 0;
1613 	uint64_t asize;
1614 	nvlist_t *nvl = NULL, *tmp;
1615 	int error;
1616 
1617 	label = malloc(sizeof (vdev_phys_t));
1618 	if (label == NULL)
1619 		return (NULL);
1620 
1621 	for (int l = 0; l < VDEV_LABELS; l++) {
1622 		const unsigned char *nvlist;
1623 
1624 		if (vdev_label_read(vd, l, label,
1625 		    offsetof(vdev_label_t, vl_vdev_phys),
1626 		    sizeof (vdev_phys_t)))
1627 			continue;
1628 
1629 		nvlist = (const unsigned char *) label->vp_nvlist;
1630 		tmp = nvlist_import(nvlist + 4, nvlist[0], nvlist[1]);
1631 		if (tmp == NULL)
1632 			continue;
1633 
1634 		error = nvlist_find(tmp, ZPOOL_CONFIG_POOL_TXG,
1635 		    DATA_TYPE_UINT64, NULL, &label_txg, NULL);
1636 		if (error != 0 || label_txg == 0) {
1637 			nvlist_destroy(nvl);
1638 			nvl = tmp;
1639 			goto done;
1640 		}
1641 
1642 		if (label_txg <= txg && label_txg > best_txg) {
1643 			best_txg = label_txg;
1644 			nvlist_destroy(nvl);
1645 			nvl = tmp;
1646 			tmp = NULL;
1647 
1648 			/*
1649 			 * Use asize from pool config. We need this
1650 			 * because we can get bad value from BIOS.
1651 			 */
1652 			if (nvlist_find(nvl, ZPOOL_CONFIG_ASIZE,
1653 			    DATA_TYPE_UINT64, NULL, &asize, NULL) == 0) {
1654 				vd->v_psize = asize +
1655 				    VDEV_LABEL_START_SIZE + VDEV_LABEL_END_SIZE;
1656 			}
1657 		}
1658 		nvlist_destroy(tmp);
1659 	}
1660 
1661 	if (best_txg == 0) {
1662 		nvlist_destroy(nvl);
1663 		nvl = NULL;
1664 	}
1665 done:
1666 	free(label);
1667 	return (nvl);
1668 }
1669 
1670 static void
1671 vdev_uberblock_load(vdev_t *vd, uberblock_t *ub)
1672 {
1673 	uberblock_t *buf;
1674 
1675 	buf = malloc(VDEV_UBERBLOCK_SIZE(vd));
1676 	if (buf == NULL)
1677 		return;
1678 
1679 	for (int l = 0; l < VDEV_LABELS; l++) {
1680 		for (int n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) {
1681 			if (vdev_label_read(vd, l, buf,
1682 			    VDEV_UBERBLOCK_OFFSET(vd, n),
1683 			    VDEV_UBERBLOCK_SIZE(vd)))
1684 				continue;
1685 			if (uberblock_verify(buf) != 0)
1686 				continue;
1687 
1688 			if (vdev_uberblock_compare(buf, ub) > 0)
1689 				*ub = *buf;
1690 		}
1691 	}
1692 	free(buf);
1693 }
1694 
1695 static int
1696 vdev_probe(vdev_phys_read_t *_read, void *read_priv, spa_t **spap)
1697 {
1698 	vdev_t vtmp;
1699 	spa_t *spa;
1700 	vdev_t *vdev;
1701 	nvlist_t *nvl;
1702 	uint64_t val;
1703 	uint64_t guid, vdev_children;
1704 	uint64_t pool_txg, pool_guid;
1705 	const char *pool_name;
1706 	int rc, namelen;
1707 
1708 	/*
1709 	 * Load the vdev label and figure out which
1710 	 * uberblock is most current.
1711 	 */
1712 	memset(&vtmp, 0, sizeof(vtmp));
1713 	vtmp.v_phys_read = _read;
1714 	vtmp.v_read_priv = read_priv;
1715 	vtmp.v_psize = P2ALIGN(ldi_get_size(read_priv),
1716 	    (uint64_t)sizeof (vdev_label_t));
1717 
1718 	/* Test for minimum device size. */
1719 	if (vtmp.v_psize < SPA_MINDEVSIZE)
1720 		return (EIO);
1721 
1722 	nvl = vdev_label_read_config(&vtmp, UINT64_MAX);
1723 	if (nvl == NULL)
1724 		return (EIO);
1725 
1726 	if (nvlist_find(nvl, ZPOOL_CONFIG_VERSION, DATA_TYPE_UINT64,
1727 	    NULL, &val, NULL) != 0) {
1728 		nvlist_destroy(nvl);
1729 		return (EIO);
1730 	}
1731 
1732 	if (!SPA_VERSION_IS_SUPPORTED(val)) {
1733 		printf("ZFS: unsupported ZFS version %u (should be %u)\n",
1734 		    (unsigned)val, (unsigned)SPA_VERSION);
1735 		nvlist_destroy(nvl);
1736 		return (EIO);
1737 	}
1738 
1739 	/* Check ZFS features for read */
1740 	rc = nvlist_check_features_for_read(nvl);
1741 	if (rc != 0) {
1742 		nvlist_destroy(nvl);
1743 		return (EIO);
1744 	}
1745 
1746 	if (nvlist_find(nvl, ZPOOL_CONFIG_POOL_STATE, DATA_TYPE_UINT64,
1747 	    NULL, &val, NULL) != 0) {
1748 		nvlist_destroy(nvl);
1749 		return (EIO);
1750 	}
1751 
1752 	if (val == POOL_STATE_DESTROYED) {
1753 		/* We don't boot only from destroyed pools. */
1754 		nvlist_destroy(nvl);
1755 		return (EIO);
1756 	}
1757 
1758 	if (nvlist_find(nvl, ZPOOL_CONFIG_POOL_TXG, DATA_TYPE_UINT64,
1759 	    NULL, &pool_txg, NULL) != 0 ||
1760 	    nvlist_find(nvl, ZPOOL_CONFIG_POOL_GUID, DATA_TYPE_UINT64,
1761 	    NULL, &pool_guid, NULL) != 0 ||
1762 	    nvlist_find(nvl, ZPOOL_CONFIG_POOL_NAME, DATA_TYPE_STRING,
1763 	    NULL, &pool_name, &namelen) != 0) {
1764 		/*
1765 		 * Cache and spare devices end up here - just ignore
1766 		 * them.
1767 		 */
1768 		nvlist_destroy(nvl);
1769 		return (EIO);
1770 	}
1771 
1772 	/*
1773 	 * Create the pool if this is the first time we've seen it.
1774 	 */
1775 	spa = spa_find_by_guid(pool_guid);
1776 	if (spa == NULL) {
1777 		char *name;
1778 
1779 		nvlist_find(nvl, ZPOOL_CONFIG_VDEV_CHILDREN,
1780 		    DATA_TYPE_UINT64, NULL, &vdev_children, NULL);
1781 		name = malloc(namelen + 1);
1782 		if (name == NULL) {
1783 			nvlist_destroy(nvl);
1784 			return (ENOMEM);
1785 		}
1786 		bcopy(pool_name, name, namelen);
1787 		name[namelen] = '\0';
1788 		spa = spa_create(pool_guid, name);
1789 		free(name);
1790 		if (spa == NULL) {
1791 			nvlist_destroy(nvl);
1792 			return (ENOMEM);
1793 		}
1794 		spa->spa_root_vdev->v_nchildren = vdev_children;
1795 	}
1796 	if (pool_txg > spa->spa_txg)
1797 		spa->spa_txg = pool_txg;
1798 
1799 	/*
1800 	 * Get the vdev tree and create our in-core copy of it.
1801 	 * If we already have a vdev with this guid, this must
1802 	 * be some kind of alias (overlapping slices, dangerously dedicated
1803 	 * disks etc).
1804 	 */
1805 	if (nvlist_find(nvl, ZPOOL_CONFIG_GUID, DATA_TYPE_UINT64,
1806 	    NULL, &guid, NULL) != 0) {
1807 		nvlist_destroy(nvl);
1808 		return (EIO);
1809 	}
1810 	vdev = vdev_find(guid);
1811 	/* Has this vdev already been inited? */
1812 	if (vdev && vdev->v_phys_read) {
1813 		nvlist_destroy(nvl);
1814 		return (EIO);
1815 	}
1816 
1817 	rc = vdev_init_from_label(spa, nvl);
1818 	nvlist_destroy(nvl);
1819 	if (rc != 0)
1820 		return (rc);
1821 
1822 	/*
1823 	 * We should already have created an incomplete vdev for this
1824 	 * vdev. Find it and initialise it with our read proc.
1825 	 */
1826 	vdev = vdev_find(guid);
1827 	if (vdev != NULL) {
1828 		vdev->v_phys_read = _read;
1829 		vdev->v_read_priv = read_priv;
1830 		vdev->v_psize = vtmp.v_psize;
1831 		/*
1832 		 * If no other state is set, mark vdev healthy.
1833 		 */
1834 		if (vdev->v_state == VDEV_STATE_UNKNOWN)
1835 			vdev->v_state = VDEV_STATE_HEALTHY;
1836 	} else {
1837 		printf("ZFS: inconsistent nvlist contents\n");
1838 		return (EIO);
1839 	}
1840 
1841 	if (vdev->v_islog)
1842 		spa->spa_with_log = vdev->v_islog;
1843 
1844 	/*
1845 	 * Re-evaluate top-level vdev state.
1846 	 */
1847 	vdev_set_state(vdev->v_top);
1848 
1849 	/*
1850 	 * Ok, we are happy with the pool so far. Lets find
1851 	 * the best uberblock and then we can actually access
1852 	 * the contents of the pool.
1853 	 */
1854 	vdev_uberblock_load(vdev, &spa->spa_uberblock);
1855 
1856 	if (spap != NULL)
1857 		*spap = spa;
1858 	return (0);
1859 }
1860 
1861 static int
1862 ilog2(int n)
1863 {
1864 	int v;
1865 
1866 	for (v = 0; v < 32; v++)
1867 		if (n == (1 << v))
1868 			return (v);
1869 	return (-1);
1870 }
1871 
1872 static int
1873 zio_read_gang(const spa_t *spa, const blkptr_t *bp, void *buf)
1874 {
1875 	blkptr_t gbh_bp;
1876 	zio_gbh_phys_t zio_gb;
1877 	char *pbuf;
1878 	int i;
1879 
1880 	/* Artificial BP for gang block header. */
1881 	gbh_bp = *bp;
1882 	BP_SET_PSIZE(&gbh_bp, SPA_GANGBLOCKSIZE);
1883 	BP_SET_LSIZE(&gbh_bp, SPA_GANGBLOCKSIZE);
1884 	BP_SET_CHECKSUM(&gbh_bp, ZIO_CHECKSUM_GANG_HEADER);
1885 	BP_SET_COMPRESS(&gbh_bp, ZIO_COMPRESS_OFF);
1886 	for (i = 0; i < SPA_DVAS_PER_BP; i++)
1887 		DVA_SET_GANG(&gbh_bp.blk_dva[i], 0);
1888 
1889 	/* Read gang header block using the artificial BP. */
1890 	if (zio_read(spa, &gbh_bp, &zio_gb))
1891 		return (EIO);
1892 
1893 	pbuf = buf;
1894 	for (i = 0; i < SPA_GBH_NBLKPTRS; i++) {
1895 		blkptr_t *gbp = &zio_gb.zg_blkptr[i];
1896 
1897 		if (BP_IS_HOLE(gbp))
1898 			continue;
1899 		if (zio_read(spa, gbp, pbuf))
1900 			return (EIO);
1901 		pbuf += BP_GET_PSIZE(gbp);
1902 	}
1903 
1904 	if (zio_checksum_verify(spa, bp, buf))
1905 		return (EIO);
1906 	return (0);
1907 }
1908 
1909 static int
1910 zio_read(const spa_t *spa, const blkptr_t *bp, void *buf)
1911 {
1912 	int cpfunc = BP_GET_COMPRESS(bp);
1913 	uint64_t align, size;
1914 	void *pbuf;
1915 	int i, error;
1916 
1917 	/*
1918 	 * Process data embedded in block pointer
1919 	 */
1920 	if (BP_IS_EMBEDDED(bp)) {
1921 		ASSERT(BPE_GET_ETYPE(bp) == BP_EMBEDDED_TYPE_DATA);
1922 
1923 		size = BPE_GET_PSIZE(bp);
1924 		ASSERT(size <= BPE_PAYLOAD_SIZE);
1925 
1926 		if (cpfunc != ZIO_COMPRESS_OFF)
1927 			pbuf = malloc(size);
1928 		else
1929 			pbuf = buf;
1930 
1931 		if (pbuf == NULL)
1932 			return (ENOMEM);
1933 
1934 		decode_embedded_bp_compressed(bp, pbuf);
1935 		error = 0;
1936 
1937 		if (cpfunc != ZIO_COMPRESS_OFF) {
1938 			error = zio_decompress_data(cpfunc, pbuf,
1939 			    size, buf, BP_GET_LSIZE(bp));
1940 			free(pbuf);
1941 		}
1942 		if (error != 0)
1943 			printf("ZFS: i/o error - unable to decompress "
1944 			    "block pointer data, error %d\n", error);
1945 		return (error);
1946 	}
1947 
1948 	error = EIO;
1949 
1950 	for (i = 0; i < SPA_DVAS_PER_BP; i++) {
1951 		const dva_t *dva = &bp->blk_dva[i];
1952 		vdev_t *vdev;
1953 		vdev_list_t *vlist;
1954 		uint64_t vdevid;
1955 		off_t offset;
1956 
1957 		if (!dva->dva_word[0] && !dva->dva_word[1])
1958 			continue;
1959 
1960 		vdevid = DVA_GET_VDEV(dva);
1961 		offset = DVA_GET_OFFSET(dva);
1962 		vlist = &spa->spa_root_vdev->v_children;
1963 		STAILQ_FOREACH(vdev, vlist, v_childlink) {
1964 			if (vdev->v_id == vdevid)
1965 				break;
1966 		}
1967 		if (!vdev || !vdev->v_read)
1968 			continue;
1969 
1970 		size = BP_GET_PSIZE(bp);
1971 		if (vdev->v_read == vdev_raidz_read) {
1972 			align = 1ULL << vdev->v_ashift;
1973 			if (P2PHASE(size, align) != 0)
1974 				size = P2ROUNDUP(size, align);
1975 		}
1976 		if (size != BP_GET_PSIZE(bp) || cpfunc != ZIO_COMPRESS_OFF)
1977 			pbuf = malloc(size);
1978 		else
1979 			pbuf = buf;
1980 
1981 		if (pbuf == NULL) {
1982 			error = ENOMEM;
1983 			break;
1984 		}
1985 
1986 		if (DVA_GET_GANG(dva))
1987 			error = zio_read_gang(spa, bp, pbuf);
1988 		else
1989 			error = vdev->v_read(vdev, bp, pbuf, offset, size);
1990 		if (error == 0) {
1991 			if (cpfunc != ZIO_COMPRESS_OFF)
1992 				error = zio_decompress_data(cpfunc, pbuf,
1993 				    BP_GET_PSIZE(bp), buf, BP_GET_LSIZE(bp));
1994 			else if (size != BP_GET_PSIZE(bp))
1995 				bcopy(pbuf, buf, BP_GET_PSIZE(bp));
1996 		} else {
1997 			printf("zio_read error: %d\n", error);
1998 		}
1999 		if (buf != pbuf)
2000 			free(pbuf);
2001 		if (error == 0)
2002 			break;
2003 	}
2004 	if (error != 0)
2005 		printf("ZFS: i/o error - all block copies unavailable\n");
2006 
2007 	return (error);
2008 }
2009 
2010 static int
2011 dnode_read(const spa_t *spa, const dnode_phys_t *dnode, off_t offset,
2012     void *buf, size_t buflen)
2013 {
2014 	int ibshift = dnode->dn_indblkshift - SPA_BLKPTRSHIFT;
2015 	int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
2016 	int nlevels = dnode->dn_nlevels;
2017 	int i, rc;
2018 
2019 	if (bsize > SPA_MAXBLOCKSIZE) {
2020 		printf("ZFS: I/O error - blocks larger than %llu are not "
2021 		    "supported\n", SPA_MAXBLOCKSIZE);
2022 		return (EIO);
2023 	}
2024 
2025 	/*
2026 	 * Note: bsize may not be a power of two here so we need to do an
2027 	 * actual divide rather than a bitshift.
2028 	 */
2029 	while (buflen > 0) {
2030 		uint64_t bn = offset / bsize;
2031 		int boff = offset % bsize;
2032 		int ibn;
2033 		const blkptr_t *indbp;
2034 		blkptr_t bp;
2035 
2036 		if (bn > dnode->dn_maxblkid)
2037 			return (EIO);
2038 
2039 		if (dnode == dnode_cache_obj && bn == dnode_cache_bn)
2040 			goto cached;
2041 
2042 		indbp = dnode->dn_blkptr;
2043 		for (i = 0; i < nlevels; i++) {
2044 			/*
2045 			 * Copy the bp from the indirect array so that
2046 			 * we can re-use the scratch buffer for multi-level
2047 			 * objects.
2048 			 */
2049 			ibn = bn >> ((nlevels - i - 1) * ibshift);
2050 			ibn &= ((1 << ibshift) - 1);
2051 			bp = indbp[ibn];
2052 			if (BP_IS_HOLE(&bp)) {
2053 				memset(dnode_cache_buf, 0, bsize);
2054 				break;
2055 			}
2056 			rc = zio_read(spa, &bp, dnode_cache_buf);
2057 			if (rc)
2058 				return (rc);
2059 			indbp = (const blkptr_t *) dnode_cache_buf;
2060 		}
2061 		dnode_cache_obj = dnode;
2062 		dnode_cache_bn = bn;
2063 	cached:
2064 
2065 		/*
2066 		 * The buffer contains our data block. Copy what we
2067 		 * need from it and loop.
2068 		 */
2069 		i = bsize - boff;
2070 		if (i > buflen) i = buflen;
2071 		memcpy(buf, &dnode_cache_buf[boff], i);
2072 		buf = ((char *)buf) + i;
2073 		offset += i;
2074 		buflen -= i;
2075 	}
2076 
2077 	return (0);
2078 }
2079 
2080 /*
2081  * Lookup a value in a microzap directory.
2082  */
2083 static int
2084 mzap_lookup(const mzap_phys_t *mz, size_t size, const char *name,
2085     uint64_t *value)
2086 {
2087 	const mzap_ent_phys_t *mze;
2088 	int chunks, i;
2089 
2090 	/*
2091 	 * Microzap objects use exactly one block. Read the whole
2092 	 * thing.
2093 	 */
2094 	chunks = size / MZAP_ENT_LEN - 1;
2095 	for (i = 0; i < chunks; i++) {
2096 		mze = &mz->mz_chunk[i];
2097 		if (strcmp(mze->mze_name, name) == 0) {
2098 			*value = mze->mze_value;
2099 			return (0);
2100 		}
2101 	}
2102 
2103 	return (ENOENT);
2104 }
2105 
2106 /*
2107  * Compare a name with a zap leaf entry. Return non-zero if the name
2108  * matches.
2109  */
2110 static int
2111 fzap_name_equal(const zap_leaf_t *zl, const zap_leaf_chunk_t *zc,
2112     const char *name)
2113 {
2114 	size_t namelen;
2115 	const zap_leaf_chunk_t *nc;
2116 	const char *p;
2117 
2118 	namelen = zc->l_entry.le_name_numints;
2119 
2120 	nc = &ZAP_LEAF_CHUNK(zl, zc->l_entry.le_name_chunk);
2121 	p = name;
2122 	while (namelen > 0) {
2123 		size_t len;
2124 
2125 		len = namelen;
2126 		if (len > ZAP_LEAF_ARRAY_BYTES)
2127 			len = ZAP_LEAF_ARRAY_BYTES;
2128 		if (memcmp(p, nc->l_array.la_array, len))
2129 			return (0);
2130 		p += len;
2131 		namelen -= len;
2132 		nc = &ZAP_LEAF_CHUNK(zl, nc->l_array.la_next);
2133 	}
2134 
2135 	return (1);
2136 }
2137 
2138 /*
2139  * Extract a uint64_t value from a zap leaf entry.
2140  */
2141 static uint64_t
2142 fzap_leaf_value(const zap_leaf_t *zl, const zap_leaf_chunk_t *zc)
2143 {
2144 	const zap_leaf_chunk_t *vc;
2145 	int i;
2146 	uint64_t value;
2147 	const uint8_t *p;
2148 
2149 	vc = &ZAP_LEAF_CHUNK(zl, zc->l_entry.le_value_chunk);
2150 	for (i = 0, value = 0, p = vc->l_array.la_array; i < 8; i++) {
2151 		value = (value << 8) | p[i];
2152 	}
2153 
2154 	return (value);
2155 }
2156 
2157 static void
2158 stv(int len, void *addr, uint64_t value)
2159 {
2160 	switch (len) {
2161 	case 1:
2162 		*(uint8_t *)addr = value;
2163 		return;
2164 	case 2:
2165 		*(uint16_t *)addr = value;
2166 		return;
2167 	case 4:
2168 		*(uint32_t *)addr = value;
2169 		return;
2170 	case 8:
2171 		*(uint64_t *)addr = value;
2172 		return;
2173 	}
2174 }
2175 
2176 /*
2177  * Extract a array from a zap leaf entry.
2178  */
2179 static void
2180 fzap_leaf_array(const zap_leaf_t *zl, const zap_leaf_chunk_t *zc,
2181     uint64_t integer_size, uint64_t num_integers, void *buf)
2182 {
2183 	uint64_t array_int_len = zc->l_entry.le_value_intlen;
2184 	uint64_t value = 0;
2185 	uint64_t *u64 = buf;
2186 	char *p = buf;
2187 	int len = MIN(zc->l_entry.le_value_numints, num_integers);
2188 	int chunk = zc->l_entry.le_value_chunk;
2189 	int byten = 0;
2190 
2191 	if (integer_size == 8 && len == 1) {
2192 		*u64 = fzap_leaf_value(zl, zc);
2193 		return;
2194 	}
2195 
2196 	while (len > 0) {
2197 		struct zap_leaf_array *la = &ZAP_LEAF_CHUNK(zl, chunk).l_array;
2198 		int i;
2199 
2200 		ASSERT3U(chunk, <, ZAP_LEAF_NUMCHUNKS(zl));
2201 		for (i = 0; i < ZAP_LEAF_ARRAY_BYTES && len > 0; i++) {
2202 			value = (value << 8) | la->la_array[i];
2203 			byten++;
2204 			if (byten == array_int_len) {
2205 				stv(integer_size, p, value);
2206 				byten = 0;
2207 				len--;
2208 				if (len == 0)
2209 					return;
2210 				p += integer_size;
2211 			}
2212 		}
2213 		chunk = la->la_next;
2214 	}
2215 }
2216 
2217 static int
2218 fzap_check_size(uint64_t integer_size, uint64_t num_integers)
2219 {
2220 
2221 	switch (integer_size) {
2222 	case 1:
2223 	case 2:
2224 	case 4:
2225 	case 8:
2226 		break;
2227 	default:
2228 		return (EINVAL);
2229 	}
2230 
2231 	if (integer_size * num_integers > ZAP_MAXVALUELEN)
2232 		return (E2BIG);
2233 
2234 	return (0);
2235 }
2236 
2237 static void
2238 zap_leaf_free(zap_leaf_t *leaf)
2239 {
2240 	free(leaf->l_phys);
2241 	free(leaf);
2242 }
2243 
2244 static int
2245 zap_get_leaf_byblk(fat_zap_t *zap, uint64_t blk, zap_leaf_t **lp)
2246 {
2247 	int bs = FZAP_BLOCK_SHIFT(zap);
2248 	int err;
2249 
2250 	*lp = malloc(sizeof(**lp));
2251 	if (*lp == NULL)
2252 		return (ENOMEM);
2253 
2254 	(*lp)->l_bs = bs;
2255 	(*lp)->l_phys = malloc(1 << bs);
2256 
2257 	if ((*lp)->l_phys == NULL) {
2258 		free(*lp);
2259 		return (ENOMEM);
2260 	}
2261 	err = dnode_read(zap->zap_spa, zap->zap_dnode, blk << bs, (*lp)->l_phys,
2262 	    1 << bs);
2263 	if (err != 0) {
2264 		zap_leaf_free(*lp);
2265 	}
2266 	return (err);
2267 }
2268 
2269 static int
2270 zap_table_load(fat_zap_t *zap, zap_table_phys_t *tbl, uint64_t idx,
2271     uint64_t *valp)
2272 {
2273 	int bs = FZAP_BLOCK_SHIFT(zap);
2274 	uint64_t blk = idx >> (bs - 3);
2275 	uint64_t off = idx & ((1 << (bs - 3)) - 1);
2276 	uint64_t *buf;
2277 	int rc;
2278 
2279 	buf = malloc(1 << zap->zap_block_shift);
2280 	if (buf == NULL)
2281 		return (ENOMEM);
2282 	rc = dnode_read(zap->zap_spa, zap->zap_dnode, (tbl->zt_blk + blk) << bs,
2283 	    buf, 1 << zap->zap_block_shift);
2284 	if (rc == 0)
2285 		*valp = buf[off];
2286 	free(buf);
2287 	return (rc);
2288 }
2289 
2290 static int
2291 zap_idx_to_blk(fat_zap_t *zap, uint64_t idx, uint64_t *valp)
2292 {
2293 	if (zap->zap_phys->zap_ptrtbl.zt_numblks == 0) {
2294 		*valp = ZAP_EMBEDDED_PTRTBL_ENT(zap, idx);
2295 		return (0);
2296 	} else {
2297 		return (zap_table_load(zap, &zap->zap_phys->zap_ptrtbl,
2298 		    idx, valp));
2299 	}
2300 }
2301 
2302 #define	ZAP_HASH_IDX(hash, n)	(((n) == 0) ? 0 : ((hash) >> (64 - (n))))
2303 static int
2304 zap_deref_leaf(fat_zap_t *zap, uint64_t h, zap_leaf_t **lp)
2305 {
2306 	uint64_t idx, blk;
2307 	int err;
2308 
2309 	idx = ZAP_HASH_IDX(h, zap->zap_phys->zap_ptrtbl.zt_shift);
2310 	err = zap_idx_to_blk(zap, idx, &blk);
2311 	if (err != 0)
2312 		return (err);
2313 	return (zap_get_leaf_byblk(zap, blk, lp));
2314 }
2315 
2316 #define	CHAIN_END	0xffff	/* end of the chunk chain */
2317 #define	LEAF_HASH(l, h) \
2318 	((ZAP_LEAF_HASH_NUMENTRIES(l)-1) & \
2319 	((h) >> \
2320 	(64 - ZAP_LEAF_HASH_SHIFT(l) - (l)->l_phys->l_hdr.lh_prefix_len)))
2321 #define	LEAF_HASH_ENTPTR(l, h)	(&(l)->l_phys->l_hash[LEAF_HASH(l, h)])
2322 
2323 static int
2324 zap_leaf_lookup(zap_leaf_t *zl, uint64_t hash, const char *name,
2325     uint64_t integer_size, uint64_t num_integers, void *value)
2326 {
2327 	int rc;
2328 	uint16_t *chunkp;
2329 	struct zap_leaf_entry *le;
2330 
2331 	/*
2332 	 * Make sure this chunk matches our hash.
2333 	 */
2334 	if (zl->l_phys->l_hdr.lh_prefix_len > 0 &&
2335 	    zl->l_phys->l_hdr.lh_prefix !=
2336 	    hash >> (64 - zl->l_phys->l_hdr.lh_prefix_len))
2337 		return (EIO);
2338 
2339 	rc = ENOENT;
2340 	for (chunkp = LEAF_HASH_ENTPTR(zl, hash);
2341 	    *chunkp != CHAIN_END; chunkp = &le->le_next) {
2342 		zap_leaf_chunk_t *zc;
2343 		uint16_t chunk = *chunkp;
2344 
2345 		le = ZAP_LEAF_ENTRY(zl, chunk);
2346 		if (le->le_hash != hash)
2347 			continue;
2348 		zc = &ZAP_LEAF_CHUNK(zl, chunk);
2349 		if (fzap_name_equal(zl, zc, name)) {
2350 			if (zc->l_entry.le_value_intlen > integer_size) {
2351 				rc = EINVAL;
2352 			} else {
2353 				fzap_leaf_array(zl, zc, integer_size,
2354 				    num_integers, value);
2355 				rc = 0;
2356 			}
2357 			break;
2358 		}
2359 	}
2360 	return (rc);
2361 }
2362 
2363 /*
2364  * Lookup a value in a fatzap directory.
2365  */
2366 static int
2367 fzap_lookup(const spa_t *spa, const dnode_phys_t *dnode, zap_phys_t *zh,
2368     const char *name, uint64_t integer_size, uint64_t num_integers,
2369     void *value)
2370 {
2371 	int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
2372 	fat_zap_t z;
2373 	zap_leaf_t *zl;
2374 	uint64_t hash;
2375 	int rc;
2376 
2377 	if (zh->zap_magic != ZAP_MAGIC)
2378 		return (EIO);
2379 
2380 	if ((rc = fzap_check_size(integer_size, num_integers)) != 0)
2381 		return (rc);
2382 
2383 	z.zap_block_shift = ilog2(bsize);
2384 	z.zap_phys = zh;
2385 	z.zap_spa = spa;
2386 	z.zap_dnode = dnode;
2387 
2388 	hash = zap_hash(zh->zap_salt, name);
2389 	rc = zap_deref_leaf(&z, hash, &zl);
2390 	if (rc != 0)
2391 		return (rc);
2392 
2393 	rc = zap_leaf_lookup(zl, hash, name, integer_size, num_integers, value);
2394 
2395 	zap_leaf_free(zl);
2396 	return (rc);
2397 }
2398 
2399 /*
2400  * Lookup a name in a zap object and return its value as a uint64_t.
2401  */
2402 static int
2403 zap_lookup(const spa_t *spa, const dnode_phys_t *dnode, const char *name,
2404     uint64_t integer_size, uint64_t num_integers, void *value)
2405 {
2406 	int rc;
2407 	zap_phys_t *zap;
2408 	size_t size = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
2409 
2410 	zap = malloc(size);
2411 	if (zap == NULL)
2412 		return (ENOMEM);
2413 
2414 	rc = dnode_read(spa, dnode, 0, zap, size);
2415 	if (rc)
2416 		goto done;
2417 
2418 	switch (zap->zap_block_type) {
2419 	case ZBT_MICRO:
2420 		rc = mzap_lookup((const mzap_phys_t *)zap, size, name, value);
2421 		break;
2422 	case ZBT_HEADER:
2423 		rc = fzap_lookup(spa, dnode, zap, name, integer_size,
2424 		    num_integers, value);
2425 		break;
2426 	default:
2427 		printf("ZFS: invalid zap_type=%" PRIx64 "\n",
2428 		    zap->zap_block_type);
2429 		rc = EIO;
2430 	}
2431 done:
2432 	free(zap);
2433 	return (rc);
2434 }
2435 
2436 /*
2437  * List a microzap directory.
2438  */
2439 static int
2440 mzap_list(const mzap_phys_t *mz, size_t size,
2441     int (*callback)(const char *, uint64_t))
2442 {
2443 	const mzap_ent_phys_t *mze;
2444 	int chunks, i, rc;
2445 
2446 	/*
2447 	 * Microzap objects use exactly one block. Read the whole
2448 	 * thing.
2449 	 */
2450 	rc = 0;
2451 	chunks = size / MZAP_ENT_LEN - 1;
2452 	for (i = 0; i < chunks; i++) {
2453 		mze = &mz->mz_chunk[i];
2454 		if (mze->mze_name[0]) {
2455 			rc = callback(mze->mze_name, mze->mze_value);
2456 			if (rc != 0)
2457 				break;
2458 		}
2459 	}
2460 
2461 	return (rc);
2462 }
2463 
2464 /*
2465  * List a fatzap directory.
2466  */
2467 static int
2468 fzap_list(const spa_t *spa, const dnode_phys_t *dnode, zap_phys_t *zh,
2469     int (*callback)(const char *, uint64_t))
2470 {
2471 	int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
2472 	fat_zap_t z;
2473 	uint64_t i;
2474 	int j, rc;
2475 
2476 	if (zh->zap_magic != ZAP_MAGIC)
2477 		return (EIO);
2478 
2479 	z.zap_block_shift = ilog2(bsize);
2480 	z.zap_phys = zh;
2481 
2482 	/*
2483 	 * This assumes that the leaf blocks start at block 1. The
2484 	 * documentation isn't exactly clear on this.
2485 	 */
2486 	zap_leaf_t zl;
2487 	zl.l_bs = z.zap_block_shift;
2488 	zl.l_phys = malloc(bsize);
2489 	if (zl.l_phys == NULL)
2490 		return (ENOMEM);
2491 
2492 	for (i = 0; i < zh->zap_num_leafs; i++) {
2493 		off_t off = ((off_t)(i + 1)) << zl.l_bs;
2494 		char name[256], *p;
2495 		uint64_t value;
2496 
2497 		if (dnode_read(spa, dnode, off, zl.l_phys, bsize)) {
2498 			free(zl.l_phys);
2499 			return (EIO);
2500 		}
2501 
2502 		for (j = 0; j < ZAP_LEAF_NUMCHUNKS(&zl); j++) {
2503 			zap_leaf_chunk_t *zc, *nc;
2504 			int namelen;
2505 
2506 			zc = &ZAP_LEAF_CHUNK(&zl, j);
2507 			if (zc->l_entry.le_type != ZAP_CHUNK_ENTRY)
2508 				continue;
2509 			namelen = zc->l_entry.le_name_numints;
2510 			if (namelen > sizeof(name))
2511 				namelen = sizeof(name);
2512 
2513 			/*
2514 			 * Paste the name back together.
2515 			 */
2516 			nc = &ZAP_LEAF_CHUNK(&zl, zc->l_entry.le_name_chunk);
2517 			p = name;
2518 			while (namelen > 0) {
2519 				int len;
2520 				len = namelen;
2521 				if (len > ZAP_LEAF_ARRAY_BYTES)
2522 					len = ZAP_LEAF_ARRAY_BYTES;
2523 				memcpy(p, nc->l_array.la_array, len);
2524 				p += len;
2525 				namelen -= len;
2526 				nc = &ZAP_LEAF_CHUNK(&zl, nc->l_array.la_next);
2527 			}
2528 
2529 			/*
2530 			 * Assume the first eight bytes of the value are
2531 			 * a uint64_t.
2532 			 */
2533 			value = fzap_leaf_value(&zl, zc);
2534 
2535 			/* printf("%s 0x%jx\n", name, (uintmax_t)value); */
2536 			rc = callback((const char *)name, value);
2537 			if (rc != 0) {
2538 				free(zl.l_phys);
2539 				return (rc);
2540 			}
2541 		}
2542 	}
2543 
2544 	free(zl.l_phys);
2545 	return (0);
2546 }
2547 
2548 static int zfs_printf(const char *name, uint64_t value __unused)
2549 {
2550 
2551 	printf("%s\n", name);
2552 
2553 	return (0);
2554 }
2555 
2556 /*
2557  * List a zap directory.
2558  */
2559 static int
2560 zap_list(const spa_t *spa, const dnode_phys_t *dnode)
2561 {
2562 	zap_phys_t *zap;
2563 	size_t size = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
2564 	int rc;
2565 
2566 	zap = malloc(size);
2567 	if (zap == NULL)
2568 		return (ENOMEM);
2569 
2570 	rc = dnode_read(spa, dnode, 0, zap, size);
2571 	if (rc == 0) {
2572 		if (zap->zap_block_type == ZBT_MICRO)
2573 			rc = mzap_list((const mzap_phys_t *)zap, size,
2574 			    zfs_printf);
2575 		else
2576 			rc = fzap_list(spa, dnode, zap, zfs_printf);
2577 	}
2578 	free(zap);
2579 	return (rc);
2580 }
2581 
2582 static int
2583 objset_get_dnode(const spa_t *spa, const objset_phys_t *os, uint64_t objnum,
2584     dnode_phys_t *dnode)
2585 {
2586 	off_t offset;
2587 
2588 	offset = objnum * sizeof(dnode_phys_t);
2589 	return dnode_read(spa, &os->os_meta_dnode, offset,
2590 		dnode, sizeof(dnode_phys_t));
2591 }
2592 
2593 /*
2594  * Lookup a name in a microzap directory.
2595  */
2596 static int
2597 mzap_rlookup(const mzap_phys_t *mz, size_t size, char *name, uint64_t value)
2598 {
2599 	const mzap_ent_phys_t *mze;
2600 	int chunks, i;
2601 
2602 	/*
2603 	 * Microzap objects use exactly one block. Read the whole
2604 	 * thing.
2605 	 */
2606 	chunks = size / MZAP_ENT_LEN - 1;
2607 	for (i = 0; i < chunks; i++) {
2608 		mze = &mz->mz_chunk[i];
2609 		if (value == mze->mze_value) {
2610 			strcpy(name, mze->mze_name);
2611 			return (0);
2612 		}
2613 	}
2614 
2615 	return (ENOENT);
2616 }
2617 
2618 static void
2619 fzap_name_copy(const zap_leaf_t *zl, const zap_leaf_chunk_t *zc, char *name)
2620 {
2621 	size_t namelen;
2622 	const zap_leaf_chunk_t *nc;
2623 	char *p;
2624 
2625 	namelen = zc->l_entry.le_name_numints;
2626 
2627 	nc = &ZAP_LEAF_CHUNK(zl, zc->l_entry.le_name_chunk);
2628 	p = name;
2629 	while (namelen > 0) {
2630 		size_t len;
2631 		len = namelen;
2632 		if (len > ZAP_LEAF_ARRAY_BYTES)
2633 			len = ZAP_LEAF_ARRAY_BYTES;
2634 		memcpy(p, nc->l_array.la_array, len);
2635 		p += len;
2636 		namelen -= len;
2637 		nc = &ZAP_LEAF_CHUNK(zl, nc->l_array.la_next);
2638 	}
2639 
2640 	*p = '\0';
2641 }
2642 
2643 static int
2644 fzap_rlookup(const spa_t *spa, const dnode_phys_t *dnode, zap_phys_t *zh,
2645     char *name, uint64_t value)
2646 {
2647 	int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
2648 	fat_zap_t z;
2649 	uint64_t i;
2650 	int j, rc;
2651 
2652 	if (zh->zap_magic != ZAP_MAGIC)
2653 		return (EIO);
2654 
2655 	z.zap_block_shift = ilog2(bsize);
2656 	z.zap_phys = zh;
2657 
2658 	/*
2659 	 * This assumes that the leaf blocks start at block 1. The
2660 	 * documentation isn't exactly clear on this.
2661 	 */
2662 	zap_leaf_t zl;
2663 	zl.l_bs = z.zap_block_shift;
2664 	zl.l_phys = malloc(bsize);
2665 	if (zl.l_phys == NULL)
2666 		return (ENOMEM);
2667 
2668 	for (i = 0; i < zh->zap_num_leafs; i++) {
2669 		off_t off = ((off_t)(i + 1)) << zl.l_bs;
2670 
2671 		rc = dnode_read(spa, dnode, off, zl.l_phys, bsize);
2672 		if (rc != 0)
2673 			goto done;
2674 
2675 		for (j = 0; j < ZAP_LEAF_NUMCHUNKS(&zl); j++) {
2676 			zap_leaf_chunk_t *zc;
2677 
2678 			zc = &ZAP_LEAF_CHUNK(&zl, j);
2679 			if (zc->l_entry.le_type != ZAP_CHUNK_ENTRY)
2680 				continue;
2681 			if (zc->l_entry.le_value_intlen != 8 ||
2682 			    zc->l_entry.le_value_numints != 1)
2683 				continue;
2684 
2685 			if (fzap_leaf_value(&zl, zc) == value) {
2686 				fzap_name_copy(&zl, zc, name);
2687 				goto done;
2688 			}
2689 		}
2690 	}
2691 
2692 	rc = ENOENT;
2693 done:
2694 	free(zl.l_phys);
2695 	return (rc);
2696 }
2697 
2698 static int
2699 zap_rlookup(const spa_t *spa, const dnode_phys_t *dnode, char *name,
2700     uint64_t value)
2701 {
2702 	zap_phys_t *zap;
2703 	size_t size = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
2704 	int rc;
2705 
2706 	zap = malloc(size);
2707 	if (zap == NULL)
2708 		return (ENOMEM);
2709 
2710 	rc = dnode_read(spa, dnode, 0, zap, size);
2711 	if (rc == 0) {
2712 		if (zap->zap_block_type == ZBT_MICRO)
2713 			rc = mzap_rlookup((const mzap_phys_t *)zap, size,
2714 			    name, value);
2715 		else
2716 			rc = fzap_rlookup(spa, dnode, zap, name, value);
2717 	}
2718 	free(zap);
2719 	return (rc);
2720 }
2721 
2722 static int
2723 zfs_rlookup(const spa_t *spa, uint64_t objnum, char *result)
2724 {
2725 	char name[256];
2726 	char component[256];
2727 	uint64_t dir_obj, parent_obj, child_dir_zapobj;
2728 	dnode_phys_t child_dir_zap, dataset, dir, parent;
2729 	dsl_dir_phys_t *dd;
2730 	dsl_dataset_phys_t *ds;
2731 	char *p;
2732 	int len;
2733 
2734 	p = &name[sizeof(name) - 1];
2735 	*p = '\0';
2736 
2737 	if (objset_get_dnode(spa, &spa->spa_mos, objnum, &dataset)) {
2738 		printf("ZFS: can't find dataset %ju\n", (uintmax_t)objnum);
2739 		return (EIO);
2740 	}
2741 	ds = (dsl_dataset_phys_t *)&dataset.dn_bonus;
2742 	dir_obj = ds->ds_dir_obj;
2743 
2744 	for (;;) {
2745 		if (objset_get_dnode(spa, &spa->spa_mos, dir_obj, &dir) != 0)
2746 			return (EIO);
2747 		dd = (dsl_dir_phys_t *)&dir.dn_bonus;
2748 
2749 		/* Actual loop condition. */
2750 		parent_obj = dd->dd_parent_obj;
2751 		if (parent_obj == 0)
2752 			break;
2753 
2754 		if (objset_get_dnode(spa, &spa->spa_mos, parent_obj,
2755 		    &parent) != 0)
2756 			return (EIO);
2757 		dd = (dsl_dir_phys_t *)&parent.dn_bonus;
2758 		child_dir_zapobj = dd->dd_child_dir_zapobj;
2759 		if (objset_get_dnode(spa, &spa->spa_mos, child_dir_zapobj,
2760 		    &child_dir_zap) != 0)
2761 			return (EIO);
2762 		if (zap_rlookup(spa, &child_dir_zap, component, dir_obj) != 0)
2763 			return (EIO);
2764 
2765 		len = strlen(component);
2766 		p -= len;
2767 		memcpy(p, component, len);
2768 		--p;
2769 		*p = '/';
2770 
2771 		/* Actual loop iteration. */
2772 		dir_obj = parent_obj;
2773 	}
2774 
2775 	if (*p != '\0')
2776 		++p;
2777 	strcpy(result, p);
2778 
2779 	return (0);
2780 }
2781 
2782 static int
2783 zfs_lookup_dataset(const spa_t *spa, const char *name, uint64_t *objnum)
2784 {
2785 	char element[256];
2786 	uint64_t dir_obj, child_dir_zapobj;
2787 	dnode_phys_t child_dir_zap, dir;
2788 	dsl_dir_phys_t *dd;
2789 	const char *p, *q;
2790 
2791 	if (objset_get_dnode(spa, &spa->spa_mos,
2792 	    DMU_POOL_DIRECTORY_OBJECT, &dir))
2793 		return (EIO);
2794 	if (zap_lookup(spa, &dir, DMU_POOL_ROOT_DATASET, sizeof (dir_obj),
2795 	    1, &dir_obj))
2796 		return (EIO);
2797 
2798 	p = name;
2799 	for (;;) {
2800 		if (objset_get_dnode(spa, &spa->spa_mos, dir_obj, &dir))
2801 			return (EIO);
2802 		dd = (dsl_dir_phys_t *)&dir.dn_bonus;
2803 
2804 		while (*p == '/')
2805 			p++;
2806 		/* Actual loop condition #1. */
2807 		if (*p == '\0')
2808 			break;
2809 
2810 		q = strchr(p, '/');
2811 		if (q) {
2812 			memcpy(element, p, q - p);
2813 			element[q - p] = '\0';
2814 			p = q + 1;
2815 		} else {
2816 			strcpy(element, p);
2817 			p += strlen(p);
2818 		}
2819 
2820 		child_dir_zapobj = dd->dd_child_dir_zapobj;
2821 		if (objset_get_dnode(spa, &spa->spa_mos, child_dir_zapobj,
2822 		    &child_dir_zap) != 0)
2823 			return (EIO);
2824 
2825 		/* Actual loop condition #2. */
2826 		if (zap_lookup(spa, &child_dir_zap, element, sizeof (dir_obj),
2827 		    1, &dir_obj) != 0)
2828 			return (ENOENT);
2829 	}
2830 
2831 	*objnum = dd->dd_head_dataset_obj;
2832 	return (0);
2833 }
2834 
2835 #ifndef BOOT2
2836 static int
2837 zfs_list_dataset(const spa_t *spa, uint64_t objnum/*, int pos, char *entry*/)
2838 {
2839 	uint64_t dir_obj, child_dir_zapobj;
2840 	dnode_phys_t child_dir_zap, dir, dataset;
2841 	dsl_dataset_phys_t *ds;
2842 	dsl_dir_phys_t *dd;
2843 
2844 	if (objset_get_dnode(spa, &spa->spa_mos, objnum, &dataset)) {
2845 		printf("ZFS: can't find dataset %ju\n", (uintmax_t)objnum);
2846 		return (EIO);
2847 	}
2848 	ds = (dsl_dataset_phys_t *)&dataset.dn_bonus;
2849 	dir_obj = ds->ds_dir_obj;
2850 
2851 	if (objset_get_dnode(spa, &spa->spa_mos, dir_obj, &dir)) {
2852 		printf("ZFS: can't find dirobj %ju\n", (uintmax_t)dir_obj);
2853 		return (EIO);
2854 	}
2855 	dd = (dsl_dir_phys_t *)&dir.dn_bonus;
2856 
2857 	child_dir_zapobj = dd->dd_child_dir_zapobj;
2858 	if (objset_get_dnode(spa, &spa->spa_mos, child_dir_zapobj,
2859 	    &child_dir_zap) != 0) {
2860 		printf("ZFS: can't find child zap %ju\n", (uintmax_t)dir_obj);
2861 		return (EIO);
2862 	}
2863 
2864 	return (zap_list(spa, &child_dir_zap) != 0);
2865 }
2866 
2867 int
2868 zfs_callback_dataset(const spa_t *spa, uint64_t objnum,
2869     int (*callback)(const char *, uint64_t))
2870 {
2871 	uint64_t dir_obj, child_dir_zapobj;
2872 	dnode_phys_t child_dir_zap, dir, dataset;
2873 	dsl_dataset_phys_t *ds;
2874 	dsl_dir_phys_t *dd;
2875 	zap_phys_t *zap;
2876 	size_t size;
2877 	int err;
2878 
2879 	err = objset_get_dnode(spa, &spa->spa_mos, objnum, &dataset);
2880 	if (err != 0) {
2881 		printf("ZFS: can't find dataset %ju\n", (uintmax_t)objnum);
2882 		return (err);
2883 	}
2884 	ds = (dsl_dataset_phys_t *)&dataset.dn_bonus;
2885 	dir_obj = ds->ds_dir_obj;
2886 
2887 	err = objset_get_dnode(spa, &spa->spa_mos, dir_obj, &dir);
2888 	if (err != 0) {
2889 		printf("ZFS: can't find dirobj %ju\n", (uintmax_t)dir_obj);
2890 		return (err);
2891 	}
2892 	dd = (dsl_dir_phys_t *)&dir.dn_bonus;
2893 
2894 	child_dir_zapobj = dd->dd_child_dir_zapobj;
2895 	err = objset_get_dnode(spa, &spa->spa_mos, child_dir_zapobj,
2896 	    &child_dir_zap);
2897 	if (err != 0) {
2898 		printf("ZFS: can't find child zap %ju\n", (uintmax_t)dir_obj);
2899 		return (err);
2900 	}
2901 
2902 	size = child_dir_zap.dn_datablkszsec << SPA_MINBLOCKSHIFT;
2903 	zap = malloc(size);
2904 	if (zap != NULL) {
2905 		err = dnode_read(spa, &child_dir_zap, 0, zap, size);
2906 		if (err != 0)
2907 			goto done;
2908 
2909 		if (zap->zap_block_type == ZBT_MICRO)
2910 			err = mzap_list((const mzap_phys_t *)zap, size,
2911 			    callback);
2912 		else
2913 			err = fzap_list(spa, &child_dir_zap, zap, callback);
2914 	} else {
2915 		err = ENOMEM;
2916 	}
2917 done:
2918 	free(zap);
2919 	return (err);
2920 }
2921 #endif
2922 
2923 /*
2924  * Find the object set given the object number of its dataset object
2925  * and return its details in *objset
2926  */
2927 static int
2928 zfs_mount_dataset(const spa_t *spa, uint64_t objnum, objset_phys_t *objset)
2929 {
2930 	dnode_phys_t dataset;
2931 	dsl_dataset_phys_t *ds;
2932 
2933 	if (objset_get_dnode(spa, &spa->spa_mos, objnum, &dataset)) {
2934 		printf("ZFS: can't find dataset %ju\n", (uintmax_t)objnum);
2935 		return (EIO);
2936 	}
2937 
2938 	ds = (dsl_dataset_phys_t *)&dataset.dn_bonus;
2939 	if (zio_read(spa, &ds->ds_bp, objset)) {
2940 		printf("ZFS: can't read object set for dataset %ju\n",
2941 		    (uintmax_t)objnum);
2942 		return (EIO);
2943 	}
2944 
2945 	return (0);
2946 }
2947 
2948 /*
2949  * Find the object set pointed to by the BOOTFS property or the root
2950  * dataset if there is none and return its details in *objset
2951  */
2952 static int
2953 zfs_get_root(const spa_t *spa, uint64_t *objid)
2954 {
2955 	dnode_phys_t dir, propdir;
2956 	uint64_t props, bootfs, root;
2957 
2958 	*objid = 0;
2959 
2960 	/*
2961 	 * Start with the MOS directory object.
2962 	 */
2963 	if (objset_get_dnode(spa, &spa->spa_mos,
2964 	    DMU_POOL_DIRECTORY_OBJECT, &dir)) {
2965 		printf("ZFS: can't read MOS object directory\n");
2966 		return (EIO);
2967 	}
2968 
2969 	/*
2970 	 * Lookup the pool_props and see if we can find a bootfs.
2971 	 */
2972 	if (zap_lookup(spa, &dir, DMU_POOL_PROPS,
2973 	    sizeof(props), 1, &props) == 0 &&
2974 	    objset_get_dnode(spa, &spa->spa_mos, props, &propdir) == 0 &&
2975 	    zap_lookup(spa, &propdir, "bootfs",
2976 	    sizeof(bootfs), 1, &bootfs) == 0 && bootfs != 0) {
2977 		*objid = bootfs;
2978 		return (0);
2979 	}
2980 	/*
2981 	 * Lookup the root dataset directory
2982 	 */
2983 	if (zap_lookup(spa, &dir, DMU_POOL_ROOT_DATASET,
2984 	    sizeof(root), 1, &root) ||
2985 	    objset_get_dnode(spa, &spa->spa_mos, root, &dir)) {
2986 		printf("ZFS: can't find root dsl_dir\n");
2987 		return (EIO);
2988 	}
2989 
2990 	/*
2991 	 * Use the information from the dataset directory's bonus buffer
2992 	 * to find the dataset object and from that the object set itself.
2993 	 */
2994 	dsl_dir_phys_t *dd = (dsl_dir_phys_t *)&dir.dn_bonus;
2995 	*objid = dd->dd_head_dataset_obj;
2996 	return (0);
2997 }
2998 
2999 static int
3000 zfs_mount(const spa_t *spa, uint64_t rootobj, struct zfsmount *mount)
3001 {
3002 
3003 	mount->spa = spa;
3004 
3005 	/*
3006 	 * Find the root object set if not explicitly provided
3007 	 */
3008 	if (rootobj == 0 && zfs_get_root(spa, &rootobj)) {
3009 		printf("ZFS: can't find root filesystem\n");
3010 		return (EIO);
3011 	}
3012 
3013 	if (zfs_mount_dataset(spa, rootobj, &mount->objset)) {
3014 		printf("ZFS: can't open root filesystem\n");
3015 		return (EIO);
3016 	}
3017 
3018 	mount->rootobj = rootobj;
3019 
3020 	return (0);
3021 }
3022 
3023 /*
3024  * callback function for feature name checks.
3025  */
3026 static int
3027 check_feature(const char *name, uint64_t value)
3028 {
3029 	int i;
3030 
3031 	if (value == 0)
3032 		return (0);
3033 	if (name[0] == '\0')
3034 		return (0);
3035 
3036 	for (i = 0; features_for_read[i] != NULL; i++) {
3037 		if (strcmp(name, features_for_read[i]) == 0)
3038 			return (0);
3039 	}
3040 	printf("ZFS: unsupported feature: %s\n", name);
3041 	return (EIO);
3042 }
3043 
3044 /*
3045  * Checks whether the MOS features that are active are supported.
3046  */
3047 static int
3048 check_mos_features(const spa_t *spa)
3049 {
3050 	dnode_phys_t dir;
3051 	zap_phys_t *zap;
3052 	uint64_t objnum;
3053 	size_t size;
3054 	int rc;
3055 
3056 	if ((rc = objset_get_dnode(spa, &spa->spa_mos, DMU_OT_OBJECT_DIRECTORY,
3057 	    &dir)) != 0)
3058 		return (rc);
3059 	if ((rc = zap_lookup(spa, &dir, DMU_POOL_FEATURES_FOR_READ,
3060 	    sizeof (objnum), 1, &objnum)) != 0) {
3061 		/*
3062 		 * It is older pool without features. As we have already
3063 		 * tested the label, just return without raising the error.
3064 		 */
3065 		return (0);
3066 	}
3067 
3068 	if ((rc = objset_get_dnode(spa, &spa->spa_mos, objnum, &dir)) != 0)
3069 		return (rc);
3070 
3071 	if (dir.dn_type != DMU_OTN_ZAP_METADATA)
3072 		return (EIO);
3073 
3074 	size = dir.dn_datablkszsec << SPA_MINBLOCKSHIFT;
3075 	zap = malloc(size);
3076 	if (zap == NULL)
3077 		return (ENOMEM);
3078 
3079 	if (dnode_read(spa, &dir, 0, zap, size)) {
3080 		free(zap);
3081 		return (EIO);
3082 	}
3083 
3084 	if (zap->zap_block_type == ZBT_MICRO)
3085 		rc = mzap_list((const mzap_phys_t *)zap, size, check_feature);
3086 	else
3087 		rc = fzap_list(spa, &dir, zap, check_feature);
3088 
3089 	free(zap);
3090 	return (rc);
3091 }
3092 
3093 static int
3094 load_nvlist(spa_t *spa, uint64_t obj, nvlist_t **value)
3095 {
3096 	dnode_phys_t dir;
3097 	size_t size;
3098 	int rc;
3099 	unsigned char *nv;
3100 
3101 	*value = NULL;
3102 	if ((rc = objset_get_dnode(spa, &spa->spa_mos, obj, &dir)) != 0)
3103 		return (rc);
3104 	if (dir.dn_type != DMU_OT_PACKED_NVLIST &&
3105 	    dir.dn_bonustype != DMU_OT_PACKED_NVLIST_SIZE) {
3106 		return (EIO);
3107 	}
3108 
3109 	if (dir.dn_bonuslen != sizeof (uint64_t))
3110 		return (EIO);
3111 
3112 	size = *(uint64_t *)DN_BONUS(&dir);
3113 	nv = malloc(size);
3114 	if (nv == NULL)
3115 		return (ENOMEM);
3116 
3117 	rc = dnode_read(spa, &dir, 0, nv, size);
3118 	if (rc != 0) {
3119 		free(nv);
3120 		nv = NULL;
3121 		return (rc);
3122 	}
3123 	*value = nvlist_import(nv + 4, nv[0], nv[1]);
3124 	free(nv);
3125 	return (rc);
3126 }
3127 
3128 static int
3129 zfs_spa_init(spa_t *spa)
3130 {
3131 	dnode_phys_t dir;
3132 	uint64_t config_object;
3133 	nvlist_t *nvlist;
3134 	int rc;
3135 
3136 	if (zio_read(spa, &spa->spa_uberblock.ub_rootbp, &spa->spa_mos)) {
3137 		printf("ZFS: can't read MOS of pool %s\n", spa->spa_name);
3138 		return (EIO);
3139 	}
3140 	if (spa->spa_mos.os_type != DMU_OST_META) {
3141 		printf("ZFS: corrupted MOS of pool %s\n", spa->spa_name);
3142 		return (EIO);
3143 	}
3144 
3145 	if (objset_get_dnode(spa, &spa->spa_mos, DMU_POOL_DIRECTORY_OBJECT,
3146 	    &dir)) {
3147 		printf("ZFS: failed to read pool %s directory object\n",
3148 		    spa->spa_name);
3149 		return (EIO);
3150 	}
3151 	/* this is allowed to fail, older pools do not have salt */
3152 	rc = zap_lookup(spa, &dir, DMU_POOL_CHECKSUM_SALT, 1,
3153 	    sizeof (spa->spa_cksum_salt.zcs_bytes),
3154 	    spa->spa_cksum_salt.zcs_bytes);
3155 
3156 	rc = check_mos_features(spa);
3157 	if (rc != 0) {
3158 		printf("ZFS: pool %s is not supported\n", spa->spa_name);
3159 		return (rc);
3160 	}
3161 
3162 	rc = zap_lookup(spa, &dir, DMU_POOL_CONFIG,
3163 	    sizeof (config_object), 1, &config_object);
3164 	if (rc != 0) {
3165 		printf("ZFS: can not read MOS %s\n", DMU_POOL_CONFIG);
3166 		return (EIO);
3167 	}
3168 	rc = load_nvlist(spa, config_object, &nvlist);
3169 	if (rc != 0)
3170 		return (rc);
3171 	/*
3172 	 * Update vdevs from MOS config. Note, we do skip encoding bytes
3173 	 * here. See also vdev_label_read_config().
3174 	 */
3175 	rc = vdev_init_from_nvlist(spa, nvlist);
3176 	nvlist_destroy(nvlist);
3177 	return (rc);
3178 }
3179 
3180 static int
3181 zfs_dnode_stat(const spa_t *spa, dnode_phys_t *dn, struct stat *sb)
3182 {
3183 
3184 	if (dn->dn_bonustype != DMU_OT_SA) {
3185 		znode_phys_t *zp = (znode_phys_t *)dn->dn_bonus;
3186 
3187 		sb->st_mode = zp->zp_mode;
3188 		sb->st_uid = zp->zp_uid;
3189 		sb->st_gid = zp->zp_gid;
3190 		sb->st_size = zp->zp_size;
3191 	} else {
3192 		sa_hdr_phys_t *sahdrp;
3193 		int hdrsize;
3194 		size_t size = 0;
3195 		void *buf = NULL;
3196 
3197 		if (dn->dn_bonuslen != 0)
3198 			sahdrp = (sa_hdr_phys_t *)DN_BONUS(dn);
3199 		else {
3200 			if ((dn->dn_flags & DNODE_FLAG_SPILL_BLKPTR) != 0) {
3201 				blkptr_t *bp = DN_SPILL_BLKPTR(dn);
3202 				int error;
3203 
3204 				size = BP_GET_LSIZE(bp);
3205 				buf = malloc(size);
3206 				if (buf == NULL)
3207 					error = ENOMEM;
3208 				else
3209 					error = zio_read(spa, bp, buf);
3210 
3211 				if (error != 0) {
3212 					free(buf);
3213 					return (error);
3214 				}
3215 				sahdrp = buf;
3216 			} else {
3217 				return (EIO);
3218 			}
3219 		}
3220 		hdrsize = SA_HDR_SIZE(sahdrp);
3221 		sb->st_mode = *(uint64_t *)((char *)sahdrp + hdrsize +
3222 		    SA_MODE_OFFSET);
3223 		sb->st_uid = *(uint64_t *)((char *)sahdrp + hdrsize +
3224 		    SA_UID_OFFSET);
3225 		sb->st_gid = *(uint64_t *)((char *)sahdrp + hdrsize +
3226 		    SA_GID_OFFSET);
3227 		sb->st_size = *(uint64_t *)((char *)sahdrp + hdrsize +
3228 		    SA_SIZE_OFFSET);
3229 		free(buf);
3230 	}
3231 
3232 	return (0);
3233 }
3234 
3235 static int
3236 zfs_dnode_readlink(const spa_t *spa, dnode_phys_t *dn, char *path, size_t psize)
3237 {
3238 	int rc = 0;
3239 
3240 	if (dn->dn_bonustype == DMU_OT_SA) {
3241 		sa_hdr_phys_t *sahdrp = NULL;
3242 		size_t size = 0;
3243 		void *buf = NULL;
3244 		int hdrsize;
3245 		char *p;
3246 
3247 		if (dn->dn_bonuslen != 0) {
3248 			sahdrp = (sa_hdr_phys_t *)DN_BONUS(dn);
3249 		} else {
3250 			blkptr_t *bp;
3251 
3252 			if ((dn->dn_flags & DNODE_FLAG_SPILL_BLKPTR) == 0)
3253 				return (EIO);
3254 			bp = DN_SPILL_BLKPTR(dn);
3255 
3256 			size = BP_GET_LSIZE(bp);
3257 			buf = malloc(size);
3258 			if (buf == NULL)
3259 				rc = ENOMEM;
3260 			else
3261 				rc = zio_read(spa, bp, buf);
3262 			if (rc != 0) {
3263 				free(buf);
3264 				return (rc);
3265 			}
3266 			sahdrp = buf;
3267 		}
3268 		hdrsize = SA_HDR_SIZE(sahdrp);
3269 		p = (char *)((uintptr_t)sahdrp + hdrsize + SA_SYMLINK_OFFSET);
3270 		memcpy(path, p, psize);
3271 		free(buf);
3272 		return (0);
3273 	}
3274 	/*
3275 	 * Second test is purely to silence bogus compiler
3276 	 * warning about accessing past the end of dn_bonus.
3277 	 */
3278 	if (psize + sizeof(znode_phys_t) <= dn->dn_bonuslen &&
3279 	    sizeof(znode_phys_t) <= sizeof(dn->dn_bonus)) {
3280 		memcpy(path, &dn->dn_bonus[sizeof(znode_phys_t)], psize);
3281 	} else {
3282 		rc = dnode_read(spa, dn, 0, path, psize);
3283 	}
3284 	return (rc);
3285 }
3286 
3287 struct obj_list {
3288 	uint64_t		objnum;
3289 	STAILQ_ENTRY(obj_list)	entry;
3290 };
3291 
3292 /*
3293  * Lookup a file and return its dnode.
3294  */
3295 static int
3296 zfs_lookup(const struct zfsmount *mount, const char *upath, dnode_phys_t *dnode)
3297 {
3298 	int rc;
3299 	uint64_t objnum;
3300 	const spa_t *spa;
3301 	dnode_phys_t dn;
3302 	const char *p, *q;
3303 	char element[256];
3304 	char path[1024];
3305 	int symlinks_followed = 0;
3306 	struct stat sb;
3307 	struct obj_list *entry, *tentry;
3308 	STAILQ_HEAD(, obj_list) on_cache = STAILQ_HEAD_INITIALIZER(on_cache);
3309 
3310 	spa = mount->spa;
3311 	if (mount->objset.os_type != DMU_OST_ZFS) {
3312 		printf("ZFS: unexpected object set type %ju\n",
3313 		    (uintmax_t)mount->objset.os_type);
3314 		return (EIO);
3315 	}
3316 
3317 	if ((entry = malloc(sizeof(struct obj_list))) == NULL)
3318 		return (ENOMEM);
3319 
3320 	/*
3321 	 * Get the root directory dnode.
3322 	 */
3323 	rc = objset_get_dnode(spa, &mount->objset, MASTER_NODE_OBJ, &dn);
3324 	if (rc) {
3325 		free(entry);
3326 		return (rc);
3327 	}
3328 
3329 	rc = zap_lookup(spa, &dn, ZFS_ROOT_OBJ, sizeof(objnum), 1, &objnum);
3330 	if (rc) {
3331 		free(entry);
3332 		return (rc);
3333 	}
3334 	entry->objnum = objnum;
3335 	STAILQ_INSERT_HEAD(&on_cache, entry, entry);
3336 
3337 	rc = objset_get_dnode(spa, &mount->objset, objnum, &dn);
3338 	if (rc != 0)
3339 		goto done;
3340 
3341 	p = upath;
3342 	while (p && *p) {
3343 		rc = objset_get_dnode(spa, &mount->objset, objnum, &dn);
3344 		if (rc != 0)
3345 			goto done;
3346 
3347 		while (*p == '/')
3348 			p++;
3349 		if (*p == '\0')
3350 			break;
3351 		q = p;
3352 		while (*q != '\0' && *q != '/')
3353 			q++;
3354 
3355 		/* skip dot */
3356 		if (p + 1 == q && p[0] == '.') {
3357 			p++;
3358 			continue;
3359 		}
3360 		/* double dot */
3361 		if (p + 2 == q && p[0] == '.' && p[1] == '.') {
3362 			p += 2;
3363 			if (STAILQ_FIRST(&on_cache) ==
3364 			    STAILQ_LAST(&on_cache, obj_list, entry)) {
3365 				rc = ENOENT;
3366 				goto done;
3367 			}
3368 			entry = STAILQ_FIRST(&on_cache);
3369 			STAILQ_REMOVE_HEAD(&on_cache, entry);
3370 			free(entry);
3371 			objnum = (STAILQ_FIRST(&on_cache))->objnum;
3372 			continue;
3373 		}
3374 		if (q - p + 1 > sizeof(element)) {
3375 			rc = ENAMETOOLONG;
3376 			goto done;
3377 		}
3378 		memcpy(element, p, q - p);
3379 		element[q - p] = 0;
3380 		p = q;
3381 
3382 		if ((rc = zfs_dnode_stat(spa, &dn, &sb)) != 0)
3383 			goto done;
3384 		if (!S_ISDIR(sb.st_mode)) {
3385 			rc = ENOTDIR;
3386 			goto done;
3387 		}
3388 
3389 		rc = zap_lookup(spa, &dn, element, sizeof (objnum), 1, &objnum);
3390 		if (rc)
3391 			goto done;
3392 		objnum = ZFS_DIRENT_OBJ(objnum);
3393 
3394 		if ((entry = malloc(sizeof(struct obj_list))) == NULL) {
3395 			rc = ENOMEM;
3396 			goto done;
3397 		}
3398 		entry->objnum = objnum;
3399 		STAILQ_INSERT_HEAD(&on_cache, entry, entry);
3400 		rc = objset_get_dnode(spa, &mount->objset, objnum, &dn);
3401 		if (rc)
3402 			goto done;
3403 
3404 		/*
3405 		 * Check for symlink.
3406 		 */
3407 		rc = zfs_dnode_stat(spa, &dn, &sb);
3408 		if (rc)
3409 			goto done;
3410 		if (S_ISLNK(sb.st_mode)) {
3411 			if (symlinks_followed > 10) {
3412 				rc = EMLINK;
3413 				goto done;
3414 			}
3415 			symlinks_followed++;
3416 
3417 			/*
3418 			 * Read the link value and copy the tail of our
3419 			 * current path onto the end.
3420 			 */
3421 			if (sb.st_size + strlen(p) + 1 > sizeof(path)) {
3422 				rc = ENAMETOOLONG;
3423 				goto done;
3424 			}
3425 			strcpy(&path[sb.st_size], p);
3426 
3427 			rc = zfs_dnode_readlink(spa, &dn, path, sb.st_size);
3428 			if (rc != 0)
3429 				goto done;
3430 
3431 			/*
3432 			 * Restart with the new path, starting either at
3433 			 * the root or at the parent depending whether or
3434 			 * not the link is relative.
3435 			 */
3436 			p = path;
3437 			if (*p == '/') {
3438 				while (STAILQ_FIRST(&on_cache) !=
3439 				    STAILQ_LAST(&on_cache, obj_list, entry)) {
3440 					entry = STAILQ_FIRST(&on_cache);
3441 					STAILQ_REMOVE_HEAD(&on_cache, entry);
3442 					free(entry);
3443 				}
3444 			} else {
3445 				entry = STAILQ_FIRST(&on_cache);
3446 				STAILQ_REMOVE_HEAD(&on_cache, entry);
3447 				free(entry);
3448 			}
3449 			objnum = (STAILQ_FIRST(&on_cache))->objnum;
3450 		}
3451 	}
3452 
3453 	*dnode = dn;
3454 done:
3455 	STAILQ_FOREACH_SAFE(entry, &on_cache, entry, tentry)
3456 		free(entry);
3457 	return (rc);
3458 }
3459