xref: /titanic_51/usr/src/uts/common/fs/zfs/vdev.c (revision 7f11fd00fc23e2af7ae21cc8837a2b86380dcfa7)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
24  * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
25  * Copyright 2015 Nexenta Systems, Inc.  All rights reserved.
26  * Copyright (c) 2014 Integros [integros.com]
27  */
28 
29 #include <sys/zfs_context.h>
30 #include <sys/fm/fs/zfs.h>
31 #include <sys/spa.h>
32 #include <sys/spa_impl.h>
33 #include <sys/dmu.h>
34 #include <sys/dmu_tx.h>
35 #include <sys/vdev_impl.h>
36 #include <sys/uberblock_impl.h>
37 #include <sys/metaslab.h>
38 #include <sys/metaslab_impl.h>
39 #include <sys/space_map.h>
40 #include <sys/space_reftree.h>
41 #include <sys/zio.h>
42 #include <sys/zap.h>
43 #include <sys/fs/zfs.h>
44 #include <sys/arc.h>
45 #include <sys/zil.h>
46 #include <sys/dsl_scan.h>
47 
48 /*
49  * Virtual device management.
50  */
51 
52 static vdev_ops_t *vdev_ops_table[] = {
53 	&vdev_root_ops,
54 	&vdev_raidz_ops,
55 	&vdev_mirror_ops,
56 	&vdev_replacing_ops,
57 	&vdev_spare_ops,
58 	&vdev_disk_ops,
59 	&vdev_file_ops,
60 	&vdev_missing_ops,
61 	&vdev_hole_ops,
62 	NULL
63 };
64 
65 /* maximum scrub/resilver I/O queue per leaf vdev */
66 int zfs_scrub_limit = 10;
67 
68 /*
69  * When a vdev is added, it will be divided into approximately (but no
70  * more than) this number of metaslabs.
71  */
72 int metaslabs_per_vdev = 200;
73 
74 /*
75  * Given a vdev type, return the appropriate ops vector.
76  */
77 static vdev_ops_t *
78 vdev_getops(const char *type)
79 {
80 	vdev_ops_t *ops, **opspp;
81 
82 	for (opspp = vdev_ops_table; (ops = *opspp) != NULL; opspp++)
83 		if (strcmp(ops->vdev_op_type, type) == 0)
84 			break;
85 
86 	return (ops);
87 }
88 
89 /*
90  * Default asize function: return the MAX of psize with the asize of
91  * all children.  This is what's used by anything other than RAID-Z.
92  */
93 uint64_t
94 vdev_default_asize(vdev_t *vd, uint64_t psize)
95 {
96 	uint64_t asize = P2ROUNDUP(psize, 1ULL << vd->vdev_top->vdev_ashift);
97 	uint64_t csize;
98 
99 	for (int c = 0; c < vd->vdev_children; c++) {
100 		csize = vdev_psize_to_asize(vd->vdev_child[c], psize);
101 		asize = MAX(asize, csize);
102 	}
103 
104 	return (asize);
105 }
106 
107 /*
108  * Get the minimum allocatable size. We define the allocatable size as
109  * the vdev's asize rounded to the nearest metaslab. This allows us to
110  * replace or attach devices which don't have the same physical size but
111  * can still satisfy the same number of allocations.
112  */
113 uint64_t
114 vdev_get_min_asize(vdev_t *vd)
115 {
116 	vdev_t *pvd = vd->vdev_parent;
117 
118 	/*
119 	 * If our parent is NULL (inactive spare or cache) or is the root,
120 	 * just return our own asize.
121 	 */
122 	if (pvd == NULL)
123 		return (vd->vdev_asize);
124 
125 	/*
126 	 * The top-level vdev just returns the allocatable size rounded
127 	 * to the nearest metaslab.
128 	 */
129 	if (vd == vd->vdev_top)
130 		return (P2ALIGN(vd->vdev_asize, 1ULL << vd->vdev_ms_shift));
131 
132 	/*
133 	 * The allocatable space for a raidz vdev is N * sizeof(smallest child),
134 	 * so each child must provide at least 1/Nth of its asize.
135 	 */
136 	if (pvd->vdev_ops == &vdev_raidz_ops)
137 		return (pvd->vdev_min_asize / pvd->vdev_children);
138 
139 	return (pvd->vdev_min_asize);
140 }
141 
142 void
143 vdev_set_min_asize(vdev_t *vd)
144 {
145 	vd->vdev_min_asize = vdev_get_min_asize(vd);
146 
147 	for (int c = 0; c < vd->vdev_children; c++)
148 		vdev_set_min_asize(vd->vdev_child[c]);
149 }
150 
151 vdev_t *
152 vdev_lookup_top(spa_t *spa, uint64_t vdev)
153 {
154 	vdev_t *rvd = spa->spa_root_vdev;
155 
156 	ASSERT(spa_config_held(spa, SCL_ALL, RW_READER) != 0);
157 
158 	if (vdev < rvd->vdev_children) {
159 		ASSERT(rvd->vdev_child[vdev] != NULL);
160 		return (rvd->vdev_child[vdev]);
161 	}
162 
163 	return (NULL);
164 }
165 
166 vdev_t *
167 vdev_lookup_by_guid(vdev_t *vd, uint64_t guid)
168 {
169 	vdev_t *mvd;
170 
171 	if (vd->vdev_guid == guid)
172 		return (vd);
173 
174 	for (int c = 0; c < vd->vdev_children; c++)
175 		if ((mvd = vdev_lookup_by_guid(vd->vdev_child[c], guid)) !=
176 		    NULL)
177 			return (mvd);
178 
179 	return (NULL);
180 }
181 
182 static int
183 vdev_count_leaves_impl(vdev_t *vd)
184 {
185 	int n = 0;
186 
187 	if (vd->vdev_ops->vdev_op_leaf)
188 		return (1);
189 
190 	for (int c = 0; c < vd->vdev_children; c++)
191 		n += vdev_count_leaves_impl(vd->vdev_child[c]);
192 
193 	return (n);
194 }
195 
196 int
197 vdev_count_leaves(spa_t *spa)
198 {
199 	return (vdev_count_leaves_impl(spa->spa_root_vdev));
200 }
201 
202 void
203 vdev_add_child(vdev_t *pvd, vdev_t *cvd)
204 {
205 	size_t oldsize, newsize;
206 	uint64_t id = cvd->vdev_id;
207 	vdev_t **newchild;
208 	spa_t *spa = cvd->vdev_spa;
209 
210 	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
211 	ASSERT(cvd->vdev_parent == NULL);
212 
213 	cvd->vdev_parent = pvd;
214 
215 	if (pvd == NULL)
216 		return;
217 
218 	ASSERT(id >= pvd->vdev_children || pvd->vdev_child[id] == NULL);
219 
220 	oldsize = pvd->vdev_children * sizeof (vdev_t *);
221 	pvd->vdev_children = MAX(pvd->vdev_children, id + 1);
222 	newsize = pvd->vdev_children * sizeof (vdev_t *);
223 
224 	newchild = kmem_zalloc(newsize, KM_SLEEP);
225 	if (pvd->vdev_child != NULL) {
226 		bcopy(pvd->vdev_child, newchild, oldsize);
227 		kmem_free(pvd->vdev_child, oldsize);
228 	}
229 
230 	pvd->vdev_child = newchild;
231 	pvd->vdev_child[id] = cvd;
232 
233 	cvd->vdev_top = (pvd->vdev_top ? pvd->vdev_top: cvd);
234 	ASSERT(cvd->vdev_top->vdev_parent->vdev_parent == NULL);
235 
236 	/*
237 	 * Walk up all ancestors to update guid sum.
238 	 */
239 	for (; pvd != NULL; pvd = pvd->vdev_parent)
240 		pvd->vdev_guid_sum += cvd->vdev_guid_sum;
241 }
242 
243 void
244 vdev_remove_child(vdev_t *pvd, vdev_t *cvd)
245 {
246 	int c;
247 	uint_t id = cvd->vdev_id;
248 
249 	ASSERT(cvd->vdev_parent == pvd);
250 
251 	if (pvd == NULL)
252 		return;
253 
254 	ASSERT(id < pvd->vdev_children);
255 	ASSERT(pvd->vdev_child[id] == cvd);
256 
257 	pvd->vdev_child[id] = NULL;
258 	cvd->vdev_parent = NULL;
259 
260 	for (c = 0; c < pvd->vdev_children; c++)
261 		if (pvd->vdev_child[c])
262 			break;
263 
264 	if (c == pvd->vdev_children) {
265 		kmem_free(pvd->vdev_child, c * sizeof (vdev_t *));
266 		pvd->vdev_child = NULL;
267 		pvd->vdev_children = 0;
268 	}
269 
270 	/*
271 	 * Walk up all ancestors to update guid sum.
272 	 */
273 	for (; pvd != NULL; pvd = pvd->vdev_parent)
274 		pvd->vdev_guid_sum -= cvd->vdev_guid_sum;
275 }
276 
277 /*
278  * Remove any holes in the child array.
279  */
280 void
281 vdev_compact_children(vdev_t *pvd)
282 {
283 	vdev_t **newchild, *cvd;
284 	int oldc = pvd->vdev_children;
285 	int newc;
286 
287 	ASSERT(spa_config_held(pvd->vdev_spa, SCL_ALL, RW_WRITER) == SCL_ALL);
288 
289 	for (int c = newc = 0; c < oldc; c++)
290 		if (pvd->vdev_child[c])
291 			newc++;
292 
293 	newchild = kmem_alloc(newc * sizeof (vdev_t *), KM_SLEEP);
294 
295 	for (int c = newc = 0; c < oldc; c++) {
296 		if ((cvd = pvd->vdev_child[c]) != NULL) {
297 			newchild[newc] = cvd;
298 			cvd->vdev_id = newc++;
299 		}
300 	}
301 
302 	kmem_free(pvd->vdev_child, oldc * sizeof (vdev_t *));
303 	pvd->vdev_child = newchild;
304 	pvd->vdev_children = newc;
305 }
306 
307 /*
308  * Allocate and minimally initialize a vdev_t.
309  */
310 vdev_t *
311 vdev_alloc_common(spa_t *spa, uint_t id, uint64_t guid, vdev_ops_t *ops)
312 {
313 	vdev_t *vd;
314 
315 	vd = kmem_zalloc(sizeof (vdev_t), KM_SLEEP);
316 
317 	if (spa->spa_root_vdev == NULL) {
318 		ASSERT(ops == &vdev_root_ops);
319 		spa->spa_root_vdev = vd;
320 		spa->spa_load_guid = spa_generate_guid(NULL);
321 	}
322 
323 	if (guid == 0 && ops != &vdev_hole_ops) {
324 		if (spa->spa_root_vdev == vd) {
325 			/*
326 			 * The root vdev's guid will also be the pool guid,
327 			 * which must be unique among all pools.
328 			 */
329 			guid = spa_generate_guid(NULL);
330 		} else {
331 			/*
332 			 * Any other vdev's guid must be unique within the pool.
333 			 */
334 			guid = spa_generate_guid(spa);
335 		}
336 		ASSERT(!spa_guid_exists(spa_guid(spa), guid));
337 	}
338 
339 	vd->vdev_spa = spa;
340 	vd->vdev_id = id;
341 	vd->vdev_guid = guid;
342 	vd->vdev_guid_sum = guid;
343 	vd->vdev_ops = ops;
344 	vd->vdev_state = VDEV_STATE_CLOSED;
345 	vd->vdev_ishole = (ops == &vdev_hole_ops);
346 
347 	mutex_init(&vd->vdev_dtl_lock, NULL, MUTEX_DEFAULT, NULL);
348 	mutex_init(&vd->vdev_stat_lock, NULL, MUTEX_DEFAULT, NULL);
349 	mutex_init(&vd->vdev_probe_lock, NULL, MUTEX_DEFAULT, NULL);
350 	for (int t = 0; t < DTL_TYPES; t++) {
351 		vd->vdev_dtl[t] = range_tree_create(NULL, NULL,
352 		    &vd->vdev_dtl_lock);
353 	}
354 	txg_list_create(&vd->vdev_ms_list,
355 	    offsetof(struct metaslab, ms_txg_node));
356 	txg_list_create(&vd->vdev_dtl_list,
357 	    offsetof(struct vdev, vdev_dtl_node));
358 	vd->vdev_stat.vs_timestamp = gethrtime();
359 	vdev_queue_init(vd);
360 	vdev_cache_init(vd);
361 
362 	return (vd);
363 }
364 
365 /*
366  * Allocate a new vdev.  The 'alloctype' is used to control whether we are
367  * creating a new vdev or loading an existing one - the behavior is slightly
368  * different for each case.
369  */
370 int
371 vdev_alloc(spa_t *spa, vdev_t **vdp, nvlist_t *nv, vdev_t *parent, uint_t id,
372     int alloctype)
373 {
374 	vdev_ops_t *ops;
375 	char *type;
376 	uint64_t guid = 0, islog, nparity;
377 	vdev_t *vd;
378 
379 	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
380 
381 	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_TYPE, &type) != 0)
382 		return (SET_ERROR(EINVAL));
383 
384 	if ((ops = vdev_getops(type)) == NULL)
385 		return (SET_ERROR(EINVAL));
386 
387 	/*
388 	 * If this is a load, get the vdev guid from the nvlist.
389 	 * Otherwise, vdev_alloc_common() will generate one for us.
390 	 */
391 	if (alloctype == VDEV_ALLOC_LOAD) {
392 		uint64_t label_id;
393 
394 		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_ID, &label_id) ||
395 		    label_id != id)
396 			return (SET_ERROR(EINVAL));
397 
398 		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_GUID, &guid) != 0)
399 			return (SET_ERROR(EINVAL));
400 	} else if (alloctype == VDEV_ALLOC_SPARE) {
401 		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_GUID, &guid) != 0)
402 			return (SET_ERROR(EINVAL));
403 	} else if (alloctype == VDEV_ALLOC_L2CACHE) {
404 		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_GUID, &guid) != 0)
405 			return (SET_ERROR(EINVAL));
406 	} else if (alloctype == VDEV_ALLOC_ROOTPOOL) {
407 		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_GUID, &guid) != 0)
408 			return (SET_ERROR(EINVAL));
409 	}
410 
411 	/*
412 	 * The first allocated vdev must be of type 'root'.
413 	 */
414 	if (ops != &vdev_root_ops && spa->spa_root_vdev == NULL)
415 		return (SET_ERROR(EINVAL));
416 
417 	/*
418 	 * Determine whether we're a log vdev.
419 	 */
420 	islog = 0;
421 	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_IS_LOG, &islog);
422 	if (islog && spa_version(spa) < SPA_VERSION_SLOGS)
423 		return (SET_ERROR(ENOTSUP));
424 
425 	if (ops == &vdev_hole_ops && spa_version(spa) < SPA_VERSION_HOLES)
426 		return (SET_ERROR(ENOTSUP));
427 
428 	/*
429 	 * Set the nparity property for RAID-Z vdevs.
430 	 */
431 	nparity = -1ULL;
432 	if (ops == &vdev_raidz_ops) {
433 		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_NPARITY,
434 		    &nparity) == 0) {
435 			if (nparity == 0 || nparity > VDEV_RAIDZ_MAXPARITY)
436 				return (SET_ERROR(EINVAL));
437 			/*
438 			 * Previous versions could only support 1 or 2 parity
439 			 * device.
440 			 */
441 			if (nparity > 1 &&
442 			    spa_version(spa) < SPA_VERSION_RAIDZ2)
443 				return (SET_ERROR(ENOTSUP));
444 			if (nparity > 2 &&
445 			    spa_version(spa) < SPA_VERSION_RAIDZ3)
446 				return (SET_ERROR(ENOTSUP));
447 		} else {
448 			/*
449 			 * We require the parity to be specified for SPAs that
450 			 * support multiple parity levels.
451 			 */
452 			if (spa_version(spa) >= SPA_VERSION_RAIDZ2)
453 				return (SET_ERROR(EINVAL));
454 			/*
455 			 * Otherwise, we default to 1 parity device for RAID-Z.
456 			 */
457 			nparity = 1;
458 		}
459 	} else {
460 		nparity = 0;
461 	}
462 	ASSERT(nparity != -1ULL);
463 
464 	vd = vdev_alloc_common(spa, id, guid, ops);
465 
466 	vd->vdev_islog = islog;
467 	vd->vdev_nparity = nparity;
468 
469 	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_PATH, &vd->vdev_path) == 0)
470 		vd->vdev_path = spa_strdup(vd->vdev_path);
471 	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_DEVID, &vd->vdev_devid) == 0)
472 		vd->vdev_devid = spa_strdup(vd->vdev_devid);
473 	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_PHYS_PATH,
474 	    &vd->vdev_physpath) == 0)
475 		vd->vdev_physpath = spa_strdup(vd->vdev_physpath);
476 	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_FRU, &vd->vdev_fru) == 0)
477 		vd->vdev_fru = spa_strdup(vd->vdev_fru);
478 
479 	/*
480 	 * Set the whole_disk property.  If it's not specified, leave the value
481 	 * as -1.
482 	 */
483 	if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK,
484 	    &vd->vdev_wholedisk) != 0)
485 		vd->vdev_wholedisk = -1ULL;
486 
487 	/*
488 	 * Look for the 'not present' flag.  This will only be set if the device
489 	 * was not present at the time of import.
490 	 */
491 	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_NOT_PRESENT,
492 	    &vd->vdev_not_present);
493 
494 	/*
495 	 * Get the alignment requirement.
496 	 */
497 	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_ASHIFT, &vd->vdev_ashift);
498 
499 	/*
500 	 * Retrieve the vdev creation time.
501 	 */
502 	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_CREATE_TXG,
503 	    &vd->vdev_crtxg);
504 
505 	/*
506 	 * If we're a top-level vdev, try to load the allocation parameters.
507 	 */
508 	if (parent && !parent->vdev_parent &&
509 	    (alloctype == VDEV_ALLOC_LOAD || alloctype == VDEV_ALLOC_SPLIT)) {
510 		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_METASLAB_ARRAY,
511 		    &vd->vdev_ms_array);
512 		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_METASLAB_SHIFT,
513 		    &vd->vdev_ms_shift);
514 		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_ASIZE,
515 		    &vd->vdev_asize);
516 		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_REMOVING,
517 		    &vd->vdev_removing);
518 	}
519 
520 	if (parent && !parent->vdev_parent && alloctype != VDEV_ALLOC_ATTACH) {
521 		ASSERT(alloctype == VDEV_ALLOC_LOAD ||
522 		    alloctype == VDEV_ALLOC_ADD ||
523 		    alloctype == VDEV_ALLOC_SPLIT ||
524 		    alloctype == VDEV_ALLOC_ROOTPOOL);
525 		vd->vdev_mg = metaslab_group_create(islog ?
526 		    spa_log_class(spa) : spa_normal_class(spa), vd);
527 	}
528 
529 	/*
530 	 * If we're a leaf vdev, try to load the DTL object and other state.
531 	 */
532 	if (vd->vdev_ops->vdev_op_leaf &&
533 	    (alloctype == VDEV_ALLOC_LOAD || alloctype == VDEV_ALLOC_L2CACHE ||
534 	    alloctype == VDEV_ALLOC_ROOTPOOL)) {
535 		if (alloctype == VDEV_ALLOC_LOAD) {
536 			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_DTL,
537 			    &vd->vdev_dtl_object);
538 			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_UNSPARE,
539 			    &vd->vdev_unspare);
540 		}
541 
542 		if (alloctype == VDEV_ALLOC_ROOTPOOL) {
543 			uint64_t spare = 0;
544 
545 			if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_IS_SPARE,
546 			    &spare) == 0 && spare)
547 				spa_spare_add(vd);
548 		}
549 
550 		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_OFFLINE,
551 		    &vd->vdev_offline);
552 
553 		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_RESILVER_TXG,
554 		    &vd->vdev_resilver_txg);
555 
556 		/*
557 		 * When importing a pool, we want to ignore the persistent fault
558 		 * state, as the diagnosis made on another system may not be
559 		 * valid in the current context.  Local vdevs will
560 		 * remain in the faulted state.
561 		 */
562 		if (spa_load_state(spa) == SPA_LOAD_OPEN) {
563 			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_FAULTED,
564 			    &vd->vdev_faulted);
565 			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_DEGRADED,
566 			    &vd->vdev_degraded);
567 			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_REMOVED,
568 			    &vd->vdev_removed);
569 
570 			if (vd->vdev_faulted || vd->vdev_degraded) {
571 				char *aux;
572 
573 				vd->vdev_label_aux =
574 				    VDEV_AUX_ERR_EXCEEDED;
575 				if (nvlist_lookup_string(nv,
576 				    ZPOOL_CONFIG_AUX_STATE, &aux) == 0 &&
577 				    strcmp(aux, "external") == 0)
578 					vd->vdev_label_aux = VDEV_AUX_EXTERNAL;
579 			}
580 		}
581 	}
582 
583 	/*
584 	 * Add ourselves to the parent's list of children.
585 	 */
586 	vdev_add_child(parent, vd);
587 
588 	*vdp = vd;
589 
590 	return (0);
591 }
592 
593 void
594 vdev_free(vdev_t *vd)
595 {
596 	spa_t *spa = vd->vdev_spa;
597 
598 	/*
599 	 * vdev_free() implies closing the vdev first.  This is simpler than
600 	 * trying to ensure complicated semantics for all callers.
601 	 */
602 	vdev_close(vd);
603 
604 	ASSERT(!list_link_active(&vd->vdev_config_dirty_node));
605 	ASSERT(!list_link_active(&vd->vdev_state_dirty_node));
606 
607 	/*
608 	 * Free all children.
609 	 */
610 	for (int c = 0; c < vd->vdev_children; c++)
611 		vdev_free(vd->vdev_child[c]);
612 
613 	ASSERT(vd->vdev_child == NULL);
614 	ASSERT(vd->vdev_guid_sum == vd->vdev_guid);
615 
616 	/*
617 	 * Discard allocation state.
618 	 */
619 	if (vd->vdev_mg != NULL) {
620 		vdev_metaslab_fini(vd);
621 		metaslab_group_destroy(vd->vdev_mg);
622 	}
623 
624 	ASSERT0(vd->vdev_stat.vs_space);
625 	ASSERT0(vd->vdev_stat.vs_dspace);
626 	ASSERT0(vd->vdev_stat.vs_alloc);
627 
628 	/*
629 	 * Remove this vdev from its parent's child list.
630 	 */
631 	vdev_remove_child(vd->vdev_parent, vd);
632 
633 	ASSERT(vd->vdev_parent == NULL);
634 
635 	/*
636 	 * Clean up vdev structure.
637 	 */
638 	vdev_queue_fini(vd);
639 	vdev_cache_fini(vd);
640 
641 	if (vd->vdev_path)
642 		spa_strfree(vd->vdev_path);
643 	if (vd->vdev_devid)
644 		spa_strfree(vd->vdev_devid);
645 	if (vd->vdev_physpath)
646 		spa_strfree(vd->vdev_physpath);
647 	if (vd->vdev_fru)
648 		spa_strfree(vd->vdev_fru);
649 
650 	if (vd->vdev_isspare)
651 		spa_spare_remove(vd);
652 	if (vd->vdev_isl2cache)
653 		spa_l2cache_remove(vd);
654 
655 	txg_list_destroy(&vd->vdev_ms_list);
656 	txg_list_destroy(&vd->vdev_dtl_list);
657 
658 	mutex_enter(&vd->vdev_dtl_lock);
659 	space_map_close(vd->vdev_dtl_sm);
660 	for (int t = 0; t < DTL_TYPES; t++) {
661 		range_tree_vacate(vd->vdev_dtl[t], NULL, NULL);
662 		range_tree_destroy(vd->vdev_dtl[t]);
663 	}
664 	mutex_exit(&vd->vdev_dtl_lock);
665 
666 	mutex_destroy(&vd->vdev_dtl_lock);
667 	mutex_destroy(&vd->vdev_stat_lock);
668 	mutex_destroy(&vd->vdev_probe_lock);
669 
670 	if (vd == spa->spa_root_vdev)
671 		spa->spa_root_vdev = NULL;
672 
673 	kmem_free(vd, sizeof (vdev_t));
674 }
675 
676 /*
677  * Transfer top-level vdev state from svd to tvd.
678  */
679 static void
680 vdev_top_transfer(vdev_t *svd, vdev_t *tvd)
681 {
682 	spa_t *spa = svd->vdev_spa;
683 	metaslab_t *msp;
684 	vdev_t *vd;
685 	int t;
686 
687 	ASSERT(tvd == tvd->vdev_top);
688 
689 	tvd->vdev_ms_array = svd->vdev_ms_array;
690 	tvd->vdev_ms_shift = svd->vdev_ms_shift;
691 	tvd->vdev_ms_count = svd->vdev_ms_count;
692 
693 	svd->vdev_ms_array = 0;
694 	svd->vdev_ms_shift = 0;
695 	svd->vdev_ms_count = 0;
696 
697 	if (tvd->vdev_mg)
698 		ASSERT3P(tvd->vdev_mg, ==, svd->vdev_mg);
699 	tvd->vdev_mg = svd->vdev_mg;
700 	tvd->vdev_ms = svd->vdev_ms;
701 
702 	svd->vdev_mg = NULL;
703 	svd->vdev_ms = NULL;
704 
705 	if (tvd->vdev_mg != NULL)
706 		tvd->vdev_mg->mg_vd = tvd;
707 
708 	tvd->vdev_stat.vs_alloc = svd->vdev_stat.vs_alloc;
709 	tvd->vdev_stat.vs_space = svd->vdev_stat.vs_space;
710 	tvd->vdev_stat.vs_dspace = svd->vdev_stat.vs_dspace;
711 
712 	svd->vdev_stat.vs_alloc = 0;
713 	svd->vdev_stat.vs_space = 0;
714 	svd->vdev_stat.vs_dspace = 0;
715 
716 	for (t = 0; t < TXG_SIZE; t++) {
717 		while ((msp = txg_list_remove(&svd->vdev_ms_list, t)) != NULL)
718 			(void) txg_list_add(&tvd->vdev_ms_list, msp, t);
719 		while ((vd = txg_list_remove(&svd->vdev_dtl_list, t)) != NULL)
720 			(void) txg_list_add(&tvd->vdev_dtl_list, vd, t);
721 		if (txg_list_remove_this(&spa->spa_vdev_txg_list, svd, t))
722 			(void) txg_list_add(&spa->spa_vdev_txg_list, tvd, t);
723 	}
724 
725 	if (list_link_active(&svd->vdev_config_dirty_node)) {
726 		vdev_config_clean(svd);
727 		vdev_config_dirty(tvd);
728 	}
729 
730 	if (list_link_active(&svd->vdev_state_dirty_node)) {
731 		vdev_state_clean(svd);
732 		vdev_state_dirty(tvd);
733 	}
734 
735 	tvd->vdev_deflate_ratio = svd->vdev_deflate_ratio;
736 	svd->vdev_deflate_ratio = 0;
737 
738 	tvd->vdev_islog = svd->vdev_islog;
739 	svd->vdev_islog = 0;
740 }
741 
742 static void
743 vdev_top_update(vdev_t *tvd, vdev_t *vd)
744 {
745 	if (vd == NULL)
746 		return;
747 
748 	vd->vdev_top = tvd;
749 
750 	for (int c = 0; c < vd->vdev_children; c++)
751 		vdev_top_update(tvd, vd->vdev_child[c]);
752 }
753 
754 /*
755  * Add a mirror/replacing vdev above an existing vdev.
756  */
757 vdev_t *
758 vdev_add_parent(vdev_t *cvd, vdev_ops_t *ops)
759 {
760 	spa_t *spa = cvd->vdev_spa;
761 	vdev_t *pvd = cvd->vdev_parent;
762 	vdev_t *mvd;
763 
764 	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
765 
766 	mvd = vdev_alloc_common(spa, cvd->vdev_id, 0, ops);
767 
768 	mvd->vdev_asize = cvd->vdev_asize;
769 	mvd->vdev_min_asize = cvd->vdev_min_asize;
770 	mvd->vdev_max_asize = cvd->vdev_max_asize;
771 	mvd->vdev_ashift = cvd->vdev_ashift;
772 	mvd->vdev_state = cvd->vdev_state;
773 	mvd->vdev_crtxg = cvd->vdev_crtxg;
774 
775 	vdev_remove_child(pvd, cvd);
776 	vdev_add_child(pvd, mvd);
777 	cvd->vdev_id = mvd->vdev_children;
778 	vdev_add_child(mvd, cvd);
779 	vdev_top_update(cvd->vdev_top, cvd->vdev_top);
780 
781 	if (mvd == mvd->vdev_top)
782 		vdev_top_transfer(cvd, mvd);
783 
784 	return (mvd);
785 }
786 
787 /*
788  * Remove a 1-way mirror/replacing vdev from the tree.
789  */
790 void
791 vdev_remove_parent(vdev_t *cvd)
792 {
793 	vdev_t *mvd = cvd->vdev_parent;
794 	vdev_t *pvd = mvd->vdev_parent;
795 
796 	ASSERT(spa_config_held(cvd->vdev_spa, SCL_ALL, RW_WRITER) == SCL_ALL);
797 
798 	ASSERT(mvd->vdev_children == 1);
799 	ASSERT(mvd->vdev_ops == &vdev_mirror_ops ||
800 	    mvd->vdev_ops == &vdev_replacing_ops ||
801 	    mvd->vdev_ops == &vdev_spare_ops);
802 	cvd->vdev_ashift = mvd->vdev_ashift;
803 
804 	vdev_remove_child(mvd, cvd);
805 	vdev_remove_child(pvd, mvd);
806 
807 	/*
808 	 * If cvd will replace mvd as a top-level vdev, preserve mvd's guid.
809 	 * Otherwise, we could have detached an offline device, and when we
810 	 * go to import the pool we'll think we have two top-level vdevs,
811 	 * instead of a different version of the same top-level vdev.
812 	 */
813 	if (mvd->vdev_top == mvd) {
814 		uint64_t guid_delta = mvd->vdev_guid - cvd->vdev_guid;
815 		cvd->vdev_orig_guid = cvd->vdev_guid;
816 		cvd->vdev_guid += guid_delta;
817 		cvd->vdev_guid_sum += guid_delta;
818 	}
819 	cvd->vdev_id = mvd->vdev_id;
820 	vdev_add_child(pvd, cvd);
821 	vdev_top_update(cvd->vdev_top, cvd->vdev_top);
822 
823 	if (cvd == cvd->vdev_top)
824 		vdev_top_transfer(mvd, cvd);
825 
826 	ASSERT(mvd->vdev_children == 0);
827 	vdev_free(mvd);
828 }
829 
830 int
831 vdev_metaslab_init(vdev_t *vd, uint64_t txg)
832 {
833 	spa_t *spa = vd->vdev_spa;
834 	objset_t *mos = spa->spa_meta_objset;
835 	uint64_t m;
836 	uint64_t oldc = vd->vdev_ms_count;
837 	uint64_t newc = vd->vdev_asize >> vd->vdev_ms_shift;
838 	metaslab_t **mspp;
839 	int error;
840 
841 	ASSERT(txg == 0 || spa_config_held(spa, SCL_ALLOC, RW_WRITER));
842 
843 	/*
844 	 * This vdev is not being allocated from yet or is a hole.
845 	 */
846 	if (vd->vdev_ms_shift == 0)
847 		return (0);
848 
849 	ASSERT(!vd->vdev_ishole);
850 
851 	/*
852 	 * Compute the raidz-deflation ratio.  Note, we hard-code
853 	 * in 128k (1 << 17) because it is the "typical" blocksize.
854 	 * Even though SPA_MAXBLOCKSIZE changed, this algorithm can not change,
855 	 * otherwise it would inconsistently account for existing bp's.
856 	 */
857 	vd->vdev_deflate_ratio = (1 << 17) /
858 	    (vdev_psize_to_asize(vd, 1 << 17) >> SPA_MINBLOCKSHIFT);
859 
860 	ASSERT(oldc <= newc);
861 
862 	mspp = kmem_zalloc(newc * sizeof (*mspp), KM_SLEEP);
863 
864 	if (oldc != 0) {
865 		bcopy(vd->vdev_ms, mspp, oldc * sizeof (*mspp));
866 		kmem_free(vd->vdev_ms, oldc * sizeof (*mspp));
867 	}
868 
869 	vd->vdev_ms = mspp;
870 	vd->vdev_ms_count = newc;
871 
872 	for (m = oldc; m < newc; m++) {
873 		uint64_t object = 0;
874 
875 		if (txg == 0) {
876 			error = dmu_read(mos, vd->vdev_ms_array,
877 			    m * sizeof (uint64_t), sizeof (uint64_t), &object,
878 			    DMU_READ_PREFETCH);
879 			if (error)
880 				return (error);
881 		}
882 
883 		error = metaslab_init(vd->vdev_mg, m, object, txg,
884 		    &(vd->vdev_ms[m]));
885 		if (error)
886 			return (error);
887 	}
888 
889 	if (txg == 0)
890 		spa_config_enter(spa, SCL_ALLOC, FTAG, RW_WRITER);
891 
892 	/*
893 	 * If the vdev is being removed we don't activate
894 	 * the metaslabs since we want to ensure that no new
895 	 * allocations are performed on this device.
896 	 */
897 	if (oldc == 0 && !vd->vdev_removing)
898 		metaslab_group_activate(vd->vdev_mg);
899 
900 	if (txg == 0)
901 		spa_config_exit(spa, SCL_ALLOC, FTAG);
902 
903 	return (0);
904 }
905 
906 void
907 vdev_metaslab_fini(vdev_t *vd)
908 {
909 	uint64_t m;
910 	uint64_t count = vd->vdev_ms_count;
911 
912 	if (vd->vdev_ms != NULL) {
913 		metaslab_group_passivate(vd->vdev_mg);
914 		for (m = 0; m < count; m++) {
915 			metaslab_t *msp = vd->vdev_ms[m];
916 
917 			if (msp != NULL)
918 				metaslab_fini(msp);
919 		}
920 		kmem_free(vd->vdev_ms, count * sizeof (metaslab_t *));
921 		vd->vdev_ms = NULL;
922 	}
923 }
924 
925 typedef struct vdev_probe_stats {
926 	boolean_t	vps_readable;
927 	boolean_t	vps_writeable;
928 	int		vps_flags;
929 } vdev_probe_stats_t;
930 
931 static void
932 vdev_probe_done(zio_t *zio)
933 {
934 	spa_t *spa = zio->io_spa;
935 	vdev_t *vd = zio->io_vd;
936 	vdev_probe_stats_t *vps = zio->io_private;
937 
938 	ASSERT(vd->vdev_probe_zio != NULL);
939 
940 	if (zio->io_type == ZIO_TYPE_READ) {
941 		if (zio->io_error == 0)
942 			vps->vps_readable = 1;
943 		if (zio->io_error == 0 && spa_writeable(spa)) {
944 			zio_nowait(zio_write_phys(vd->vdev_probe_zio, vd,
945 			    zio->io_offset, zio->io_size, zio->io_data,
946 			    ZIO_CHECKSUM_OFF, vdev_probe_done, vps,
947 			    ZIO_PRIORITY_SYNC_WRITE, vps->vps_flags, B_TRUE));
948 		} else {
949 			zio_buf_free(zio->io_data, zio->io_size);
950 		}
951 	} else if (zio->io_type == ZIO_TYPE_WRITE) {
952 		if (zio->io_error == 0)
953 			vps->vps_writeable = 1;
954 		zio_buf_free(zio->io_data, zio->io_size);
955 	} else if (zio->io_type == ZIO_TYPE_NULL) {
956 		zio_t *pio;
957 
958 		vd->vdev_cant_read |= !vps->vps_readable;
959 		vd->vdev_cant_write |= !vps->vps_writeable;
960 
961 		if (vdev_readable(vd) &&
962 		    (vdev_writeable(vd) || !spa_writeable(spa))) {
963 			zio->io_error = 0;
964 		} else {
965 			ASSERT(zio->io_error != 0);
966 			zfs_ereport_post(FM_EREPORT_ZFS_PROBE_FAILURE,
967 			    spa, vd, NULL, 0, 0);
968 			zio->io_error = SET_ERROR(ENXIO);
969 		}
970 
971 		mutex_enter(&vd->vdev_probe_lock);
972 		ASSERT(vd->vdev_probe_zio == zio);
973 		vd->vdev_probe_zio = NULL;
974 		mutex_exit(&vd->vdev_probe_lock);
975 
976 		while ((pio = zio_walk_parents(zio)) != NULL)
977 			if (!vdev_accessible(vd, pio))
978 				pio->io_error = SET_ERROR(ENXIO);
979 
980 		kmem_free(vps, sizeof (*vps));
981 	}
982 }
983 
984 /*
985  * Determine whether this device is accessible.
986  *
987  * Read and write to several known locations: the pad regions of each
988  * vdev label but the first, which we leave alone in case it contains
989  * a VTOC.
990  */
991 zio_t *
992 vdev_probe(vdev_t *vd, zio_t *zio)
993 {
994 	spa_t *spa = vd->vdev_spa;
995 	vdev_probe_stats_t *vps = NULL;
996 	zio_t *pio;
997 
998 	ASSERT(vd->vdev_ops->vdev_op_leaf);
999 
1000 	/*
1001 	 * Don't probe the probe.
1002 	 */
1003 	if (zio && (zio->io_flags & ZIO_FLAG_PROBE))
1004 		return (NULL);
1005 
1006 	/*
1007 	 * To prevent 'probe storms' when a device fails, we create
1008 	 * just one probe i/o at a time.  All zios that want to probe
1009 	 * this vdev will become parents of the probe io.
1010 	 */
1011 	mutex_enter(&vd->vdev_probe_lock);
1012 
1013 	if ((pio = vd->vdev_probe_zio) == NULL) {
1014 		vps = kmem_zalloc(sizeof (*vps), KM_SLEEP);
1015 
1016 		vps->vps_flags = ZIO_FLAG_CANFAIL | ZIO_FLAG_PROBE |
1017 		    ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_AGGREGATE |
1018 		    ZIO_FLAG_TRYHARD;
1019 
1020 		if (spa_config_held(spa, SCL_ZIO, RW_WRITER)) {
1021 			/*
1022 			 * vdev_cant_read and vdev_cant_write can only
1023 			 * transition from TRUE to FALSE when we have the
1024 			 * SCL_ZIO lock as writer; otherwise they can only
1025 			 * transition from FALSE to TRUE.  This ensures that
1026 			 * any zio looking at these values can assume that
1027 			 * failures persist for the life of the I/O.  That's
1028 			 * important because when a device has intermittent
1029 			 * connectivity problems, we want to ensure that
1030 			 * they're ascribed to the device (ENXIO) and not
1031 			 * the zio (EIO).
1032 			 *
1033 			 * Since we hold SCL_ZIO as writer here, clear both
1034 			 * values so the probe can reevaluate from first
1035 			 * principles.
1036 			 */
1037 			vps->vps_flags |= ZIO_FLAG_CONFIG_WRITER;
1038 			vd->vdev_cant_read = B_FALSE;
1039 			vd->vdev_cant_write = B_FALSE;
1040 		}
1041 
1042 		vd->vdev_probe_zio = pio = zio_null(NULL, spa, vd,
1043 		    vdev_probe_done, vps,
1044 		    vps->vps_flags | ZIO_FLAG_DONT_PROPAGATE);
1045 
1046 		/*
1047 		 * We can't change the vdev state in this context, so we
1048 		 * kick off an async task to do it on our behalf.
1049 		 */
1050 		if (zio != NULL) {
1051 			vd->vdev_probe_wanted = B_TRUE;
1052 			spa_async_request(spa, SPA_ASYNC_PROBE);
1053 		}
1054 	}
1055 
1056 	if (zio != NULL)
1057 		zio_add_child(zio, pio);
1058 
1059 	mutex_exit(&vd->vdev_probe_lock);
1060 
1061 	if (vps == NULL) {
1062 		ASSERT(zio != NULL);
1063 		return (NULL);
1064 	}
1065 
1066 	for (int l = 1; l < VDEV_LABELS; l++) {
1067 		zio_nowait(zio_read_phys(pio, vd,
1068 		    vdev_label_offset(vd->vdev_psize, l,
1069 		    offsetof(vdev_label_t, vl_pad2)),
1070 		    VDEV_PAD_SIZE, zio_buf_alloc(VDEV_PAD_SIZE),
1071 		    ZIO_CHECKSUM_OFF, vdev_probe_done, vps,
1072 		    ZIO_PRIORITY_SYNC_READ, vps->vps_flags, B_TRUE));
1073 	}
1074 
1075 	if (zio == NULL)
1076 		return (pio);
1077 
1078 	zio_nowait(pio);
1079 	return (NULL);
1080 }
1081 
1082 static void
1083 vdev_open_child(void *arg)
1084 {
1085 	vdev_t *vd = arg;
1086 
1087 	vd->vdev_open_thread = curthread;
1088 	vd->vdev_open_error = vdev_open(vd);
1089 	vd->vdev_open_thread = NULL;
1090 }
1091 
1092 boolean_t
1093 vdev_uses_zvols(vdev_t *vd)
1094 {
1095 	if (vd->vdev_path && strncmp(vd->vdev_path, ZVOL_DIR,
1096 	    strlen(ZVOL_DIR)) == 0)
1097 		return (B_TRUE);
1098 	for (int c = 0; c < vd->vdev_children; c++)
1099 		if (vdev_uses_zvols(vd->vdev_child[c]))
1100 			return (B_TRUE);
1101 	return (B_FALSE);
1102 }
1103 
1104 void
1105 vdev_open_children(vdev_t *vd)
1106 {
1107 	taskq_t *tq;
1108 	int children = vd->vdev_children;
1109 
1110 	/*
1111 	 * in order to handle pools on top of zvols, do the opens
1112 	 * in a single thread so that the same thread holds the
1113 	 * spa_namespace_lock
1114 	 */
1115 	if (vdev_uses_zvols(vd)) {
1116 		for (int c = 0; c < children; c++)
1117 			vd->vdev_child[c]->vdev_open_error =
1118 			    vdev_open(vd->vdev_child[c]);
1119 		return;
1120 	}
1121 	tq = taskq_create("vdev_open", children, minclsyspri,
1122 	    children, children, TASKQ_PREPOPULATE);
1123 
1124 	for (int c = 0; c < children; c++)
1125 		VERIFY(taskq_dispatch(tq, vdev_open_child, vd->vdev_child[c],
1126 		    TQ_SLEEP) != NULL);
1127 
1128 	taskq_destroy(tq);
1129 }
1130 
1131 /*
1132  * Prepare a virtual device for access.
1133  */
1134 int
1135 vdev_open(vdev_t *vd)
1136 {
1137 	spa_t *spa = vd->vdev_spa;
1138 	int error;
1139 	uint64_t osize = 0;
1140 	uint64_t max_osize = 0;
1141 	uint64_t asize, max_asize, psize;
1142 	uint64_t ashift = 0;
1143 
1144 	ASSERT(vd->vdev_open_thread == curthread ||
1145 	    spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
1146 	ASSERT(vd->vdev_state == VDEV_STATE_CLOSED ||
1147 	    vd->vdev_state == VDEV_STATE_CANT_OPEN ||
1148 	    vd->vdev_state == VDEV_STATE_OFFLINE);
1149 
1150 	vd->vdev_stat.vs_aux = VDEV_AUX_NONE;
1151 	vd->vdev_cant_read = B_FALSE;
1152 	vd->vdev_cant_write = B_FALSE;
1153 	vd->vdev_min_asize = vdev_get_min_asize(vd);
1154 
1155 	/*
1156 	 * If this vdev is not removed, check its fault status.  If it's
1157 	 * faulted, bail out of the open.
1158 	 */
1159 	if (!vd->vdev_removed && vd->vdev_faulted) {
1160 		ASSERT(vd->vdev_children == 0);
1161 		ASSERT(vd->vdev_label_aux == VDEV_AUX_ERR_EXCEEDED ||
1162 		    vd->vdev_label_aux == VDEV_AUX_EXTERNAL);
1163 		vdev_set_state(vd, B_TRUE, VDEV_STATE_FAULTED,
1164 		    vd->vdev_label_aux);
1165 		return (SET_ERROR(ENXIO));
1166 	} else if (vd->vdev_offline) {
1167 		ASSERT(vd->vdev_children == 0);
1168 		vdev_set_state(vd, B_TRUE, VDEV_STATE_OFFLINE, VDEV_AUX_NONE);
1169 		return (SET_ERROR(ENXIO));
1170 	}
1171 
1172 	error = vd->vdev_ops->vdev_op_open(vd, &osize, &max_osize, &ashift);
1173 
1174 	/*
1175 	 * Reset the vdev_reopening flag so that we actually close
1176 	 * the vdev on error.
1177 	 */
1178 	vd->vdev_reopening = B_FALSE;
1179 	if (zio_injection_enabled && error == 0)
1180 		error = zio_handle_device_injection(vd, NULL, ENXIO);
1181 
1182 	if (error) {
1183 		if (vd->vdev_removed &&
1184 		    vd->vdev_stat.vs_aux != VDEV_AUX_OPEN_FAILED)
1185 			vd->vdev_removed = B_FALSE;
1186 
1187 		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
1188 		    vd->vdev_stat.vs_aux);
1189 		return (error);
1190 	}
1191 
1192 	vd->vdev_removed = B_FALSE;
1193 
1194 	/*
1195 	 * Recheck the faulted flag now that we have confirmed that
1196 	 * the vdev is accessible.  If we're faulted, bail.
1197 	 */
1198 	if (vd->vdev_faulted) {
1199 		ASSERT(vd->vdev_children == 0);
1200 		ASSERT(vd->vdev_label_aux == VDEV_AUX_ERR_EXCEEDED ||
1201 		    vd->vdev_label_aux == VDEV_AUX_EXTERNAL);
1202 		vdev_set_state(vd, B_TRUE, VDEV_STATE_FAULTED,
1203 		    vd->vdev_label_aux);
1204 		return (SET_ERROR(ENXIO));
1205 	}
1206 
1207 	if (vd->vdev_degraded) {
1208 		ASSERT(vd->vdev_children == 0);
1209 		vdev_set_state(vd, B_TRUE, VDEV_STATE_DEGRADED,
1210 		    VDEV_AUX_ERR_EXCEEDED);
1211 	} else {
1212 		vdev_set_state(vd, B_TRUE, VDEV_STATE_HEALTHY, 0);
1213 	}
1214 
1215 	/*
1216 	 * For hole or missing vdevs we just return success.
1217 	 */
1218 	if (vd->vdev_ishole || vd->vdev_ops == &vdev_missing_ops)
1219 		return (0);
1220 
1221 	for (int c = 0; c < vd->vdev_children; c++) {
1222 		if (vd->vdev_child[c]->vdev_state != VDEV_STATE_HEALTHY) {
1223 			vdev_set_state(vd, B_TRUE, VDEV_STATE_DEGRADED,
1224 			    VDEV_AUX_NONE);
1225 			break;
1226 		}
1227 	}
1228 
1229 	osize = P2ALIGN(osize, (uint64_t)sizeof (vdev_label_t));
1230 	max_osize = P2ALIGN(max_osize, (uint64_t)sizeof (vdev_label_t));
1231 
1232 	if (vd->vdev_children == 0) {
1233 		if (osize < SPA_MINDEVSIZE) {
1234 			vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
1235 			    VDEV_AUX_TOO_SMALL);
1236 			return (SET_ERROR(EOVERFLOW));
1237 		}
1238 		psize = osize;
1239 		asize = osize - (VDEV_LABEL_START_SIZE + VDEV_LABEL_END_SIZE);
1240 		max_asize = max_osize - (VDEV_LABEL_START_SIZE +
1241 		    VDEV_LABEL_END_SIZE);
1242 	} else {
1243 		if (vd->vdev_parent != NULL && osize < SPA_MINDEVSIZE -
1244 		    (VDEV_LABEL_START_SIZE + VDEV_LABEL_END_SIZE)) {
1245 			vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
1246 			    VDEV_AUX_TOO_SMALL);
1247 			return (SET_ERROR(EOVERFLOW));
1248 		}
1249 		psize = 0;
1250 		asize = osize;
1251 		max_asize = max_osize;
1252 	}
1253 
1254 	vd->vdev_psize = psize;
1255 
1256 	/*
1257 	 * Make sure the allocatable size hasn't shrunk.
1258 	 */
1259 	if (asize < vd->vdev_min_asize) {
1260 		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
1261 		    VDEV_AUX_BAD_LABEL);
1262 		return (SET_ERROR(EINVAL));
1263 	}
1264 
1265 	if (vd->vdev_asize == 0) {
1266 		/*
1267 		 * This is the first-ever open, so use the computed values.
1268 		 * For testing purposes, a higher ashift can be requested.
1269 		 */
1270 		vd->vdev_asize = asize;
1271 		vd->vdev_max_asize = max_asize;
1272 		vd->vdev_ashift = MAX(ashift, vd->vdev_ashift);
1273 	} else {
1274 		/*
1275 		 * Detect if the alignment requirement has increased.
1276 		 * We don't want to make the pool unavailable, just
1277 		 * issue a warning instead.
1278 		 */
1279 		if (ashift > vd->vdev_top->vdev_ashift &&
1280 		    vd->vdev_ops->vdev_op_leaf) {
1281 			cmn_err(CE_WARN,
1282 			    "Disk, '%s', has a block alignment that is "
1283 			    "larger than the pool's alignment\n",
1284 			    vd->vdev_path);
1285 		}
1286 		vd->vdev_max_asize = max_asize;
1287 	}
1288 
1289 	/*
1290 	 * If all children are healthy and the asize has increased,
1291 	 * then we've experienced dynamic LUN growth.  If automatic
1292 	 * expansion is enabled then use the additional space.
1293 	 */
1294 	if (vd->vdev_state == VDEV_STATE_HEALTHY && asize > vd->vdev_asize &&
1295 	    (vd->vdev_expanding || spa->spa_autoexpand))
1296 		vd->vdev_asize = asize;
1297 
1298 	vdev_set_min_asize(vd);
1299 
1300 	/*
1301 	 * Ensure we can issue some IO before declaring the
1302 	 * vdev open for business.
1303 	 */
1304 	if (vd->vdev_ops->vdev_op_leaf &&
1305 	    (error = zio_wait(vdev_probe(vd, NULL))) != 0) {
1306 		vdev_set_state(vd, B_TRUE, VDEV_STATE_FAULTED,
1307 		    VDEV_AUX_ERR_EXCEEDED);
1308 		return (error);
1309 	}
1310 
1311 	/*
1312 	 * Track the min and max ashift values for normal data devices.
1313 	 */
1314 	if (vd->vdev_top == vd && vd->vdev_ashift != 0 &&
1315 	    !vd->vdev_islog && vd->vdev_aux == NULL) {
1316 		if (vd->vdev_ashift > spa->spa_max_ashift)
1317 			spa->spa_max_ashift = vd->vdev_ashift;
1318 		if (vd->vdev_ashift < spa->spa_min_ashift)
1319 			spa->spa_min_ashift = vd->vdev_ashift;
1320 	}
1321 
1322 	/*
1323 	 * If a leaf vdev has a DTL, and seems healthy, then kick off a
1324 	 * resilver.  But don't do this if we are doing a reopen for a scrub,
1325 	 * since this would just restart the scrub we are already doing.
1326 	 */
1327 	if (vd->vdev_ops->vdev_op_leaf && !spa->spa_scrub_reopen &&
1328 	    vdev_resilver_needed(vd, NULL, NULL))
1329 		spa_async_request(spa, SPA_ASYNC_RESILVER);
1330 
1331 	return (0);
1332 }
1333 
1334 /*
1335  * Called once the vdevs are all opened, this routine validates the label
1336  * contents.  This needs to be done before vdev_load() so that we don't
1337  * inadvertently do repair I/Os to the wrong device.
1338  *
1339  * If 'strict' is false ignore the spa guid check. This is necessary because
1340  * if the machine crashed during a re-guid the new guid might have been written
1341  * to all of the vdev labels, but not the cached config. The strict check
1342  * will be performed when the pool is opened again using the mos config.
1343  *
1344  * This function will only return failure if one of the vdevs indicates that it
1345  * has since been destroyed or exported.  This is only possible if
1346  * /etc/zfs/zpool.cache was readonly at the time.  Otherwise, the vdev state
1347  * will be updated but the function will return 0.
1348  */
1349 int
1350 vdev_validate(vdev_t *vd, boolean_t strict)
1351 {
1352 	spa_t *spa = vd->vdev_spa;
1353 	nvlist_t *label;
1354 	uint64_t guid = 0, top_guid;
1355 	uint64_t state;
1356 
1357 	for (int c = 0; c < vd->vdev_children; c++)
1358 		if (vdev_validate(vd->vdev_child[c], strict) != 0)
1359 			return (SET_ERROR(EBADF));
1360 
1361 	/*
1362 	 * If the device has already failed, or was marked offline, don't do
1363 	 * any further validation.  Otherwise, label I/O will fail and we will
1364 	 * overwrite the previous state.
1365 	 */
1366 	if (vd->vdev_ops->vdev_op_leaf && vdev_readable(vd)) {
1367 		uint64_t aux_guid = 0;
1368 		nvlist_t *nvl;
1369 		uint64_t txg = spa_last_synced_txg(spa) != 0 ?
1370 		    spa_last_synced_txg(spa) : -1ULL;
1371 
1372 		if ((label = vdev_label_read_config(vd, txg)) == NULL) {
1373 			vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
1374 			    VDEV_AUX_BAD_LABEL);
1375 			return (0);
1376 		}
1377 
1378 		/*
1379 		 * Determine if this vdev has been split off into another
1380 		 * pool.  If so, then refuse to open it.
1381 		 */
1382 		if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_SPLIT_GUID,
1383 		    &aux_guid) == 0 && aux_guid == spa_guid(spa)) {
1384 			vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
1385 			    VDEV_AUX_SPLIT_POOL);
1386 			nvlist_free(label);
1387 			return (0);
1388 		}
1389 
1390 		if (strict && (nvlist_lookup_uint64(label,
1391 		    ZPOOL_CONFIG_POOL_GUID, &guid) != 0 ||
1392 		    guid != spa_guid(spa))) {
1393 			vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
1394 			    VDEV_AUX_CORRUPT_DATA);
1395 			nvlist_free(label);
1396 			return (0);
1397 		}
1398 
1399 		if (nvlist_lookup_nvlist(label, ZPOOL_CONFIG_VDEV_TREE, &nvl)
1400 		    != 0 || nvlist_lookup_uint64(nvl, ZPOOL_CONFIG_ORIG_GUID,
1401 		    &aux_guid) != 0)
1402 			aux_guid = 0;
1403 
1404 		/*
1405 		 * If this vdev just became a top-level vdev because its
1406 		 * sibling was detached, it will have adopted the parent's
1407 		 * vdev guid -- but the label may or may not be on disk yet.
1408 		 * Fortunately, either version of the label will have the
1409 		 * same top guid, so if we're a top-level vdev, we can
1410 		 * safely compare to that instead.
1411 		 *
1412 		 * If we split this vdev off instead, then we also check the
1413 		 * original pool's guid.  We don't want to consider the vdev
1414 		 * corrupt if it is partway through a split operation.
1415 		 */
1416 		if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID,
1417 		    &guid) != 0 ||
1418 		    nvlist_lookup_uint64(label, ZPOOL_CONFIG_TOP_GUID,
1419 		    &top_guid) != 0 ||
1420 		    ((vd->vdev_guid != guid && vd->vdev_guid != aux_guid) &&
1421 		    (vd->vdev_guid != top_guid || vd != vd->vdev_top))) {
1422 			vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
1423 			    VDEV_AUX_CORRUPT_DATA);
1424 			nvlist_free(label);
1425 			return (0);
1426 		}
1427 
1428 		if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE,
1429 		    &state) != 0) {
1430 			vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
1431 			    VDEV_AUX_CORRUPT_DATA);
1432 			nvlist_free(label);
1433 			return (0);
1434 		}
1435 
1436 		nvlist_free(label);
1437 
1438 		/*
1439 		 * If this is a verbatim import, no need to check the
1440 		 * state of the pool.
1441 		 */
1442 		if (!(spa->spa_import_flags & ZFS_IMPORT_VERBATIM) &&
1443 		    spa_load_state(spa) == SPA_LOAD_OPEN &&
1444 		    state != POOL_STATE_ACTIVE)
1445 			return (SET_ERROR(EBADF));
1446 
1447 		/*
1448 		 * If we were able to open and validate a vdev that was
1449 		 * previously marked permanently unavailable, clear that state
1450 		 * now.
1451 		 */
1452 		if (vd->vdev_not_present)
1453 			vd->vdev_not_present = 0;
1454 	}
1455 
1456 	return (0);
1457 }
1458 
1459 /*
1460  * Close a virtual device.
1461  */
1462 void
1463 vdev_close(vdev_t *vd)
1464 {
1465 	spa_t *spa = vd->vdev_spa;
1466 	vdev_t *pvd = vd->vdev_parent;
1467 
1468 	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
1469 
1470 	/*
1471 	 * If our parent is reopening, then we are as well, unless we are
1472 	 * going offline.
1473 	 */
1474 	if (pvd != NULL && pvd->vdev_reopening)
1475 		vd->vdev_reopening = (pvd->vdev_reopening && !vd->vdev_offline);
1476 
1477 	vd->vdev_ops->vdev_op_close(vd);
1478 
1479 	vdev_cache_purge(vd);
1480 
1481 	/*
1482 	 * We record the previous state before we close it, so that if we are
1483 	 * doing a reopen(), we don't generate FMA ereports if we notice that
1484 	 * it's still faulted.
1485 	 */
1486 	vd->vdev_prevstate = vd->vdev_state;
1487 
1488 	if (vd->vdev_offline)
1489 		vd->vdev_state = VDEV_STATE_OFFLINE;
1490 	else
1491 		vd->vdev_state = VDEV_STATE_CLOSED;
1492 	vd->vdev_stat.vs_aux = VDEV_AUX_NONE;
1493 }
1494 
1495 void
1496 vdev_hold(vdev_t *vd)
1497 {
1498 	spa_t *spa = vd->vdev_spa;
1499 
1500 	ASSERT(spa_is_root(spa));
1501 	if (spa->spa_state == POOL_STATE_UNINITIALIZED)
1502 		return;
1503 
1504 	for (int c = 0; c < vd->vdev_children; c++)
1505 		vdev_hold(vd->vdev_child[c]);
1506 
1507 	if (vd->vdev_ops->vdev_op_leaf)
1508 		vd->vdev_ops->vdev_op_hold(vd);
1509 }
1510 
1511 void
1512 vdev_rele(vdev_t *vd)
1513 {
1514 	spa_t *spa = vd->vdev_spa;
1515 
1516 	ASSERT(spa_is_root(spa));
1517 	for (int c = 0; c < vd->vdev_children; c++)
1518 		vdev_rele(vd->vdev_child[c]);
1519 
1520 	if (vd->vdev_ops->vdev_op_leaf)
1521 		vd->vdev_ops->vdev_op_rele(vd);
1522 }
1523 
1524 /*
1525  * Reopen all interior vdevs and any unopened leaves.  We don't actually
1526  * reopen leaf vdevs which had previously been opened as they might deadlock
1527  * on the spa_config_lock.  Instead we only obtain the leaf's physical size.
1528  * If the leaf has never been opened then open it, as usual.
1529  */
1530 void
1531 vdev_reopen(vdev_t *vd)
1532 {
1533 	spa_t *spa = vd->vdev_spa;
1534 
1535 	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
1536 
1537 	/* set the reopening flag unless we're taking the vdev offline */
1538 	vd->vdev_reopening = !vd->vdev_offline;
1539 	vdev_close(vd);
1540 	(void) vdev_open(vd);
1541 
1542 	/*
1543 	 * Call vdev_validate() here to make sure we have the same device.
1544 	 * Otherwise, a device with an invalid label could be successfully
1545 	 * opened in response to vdev_reopen().
1546 	 */
1547 	if (vd->vdev_aux) {
1548 		(void) vdev_validate_aux(vd);
1549 		if (vdev_readable(vd) && vdev_writeable(vd) &&
1550 		    vd->vdev_aux == &spa->spa_l2cache &&
1551 		    !l2arc_vdev_present(vd))
1552 			l2arc_add_vdev(spa, vd);
1553 	} else {
1554 		(void) vdev_validate(vd, B_TRUE);
1555 	}
1556 
1557 	/*
1558 	 * Reassess parent vdev's health.
1559 	 */
1560 	vdev_propagate_state(vd);
1561 }
1562 
1563 int
1564 vdev_create(vdev_t *vd, uint64_t txg, boolean_t isreplacing)
1565 {
1566 	int error;
1567 
1568 	/*
1569 	 * Normally, partial opens (e.g. of a mirror) are allowed.
1570 	 * For a create, however, we want to fail the request if
1571 	 * there are any components we can't open.
1572 	 */
1573 	error = vdev_open(vd);
1574 
1575 	if (error || vd->vdev_state != VDEV_STATE_HEALTHY) {
1576 		vdev_close(vd);
1577 		return (error ? error : ENXIO);
1578 	}
1579 
1580 	/*
1581 	 * Recursively load DTLs and initialize all labels.
1582 	 */
1583 	if ((error = vdev_dtl_load(vd)) != 0 ||
1584 	    (error = vdev_label_init(vd, txg, isreplacing ?
1585 	    VDEV_LABEL_REPLACE : VDEV_LABEL_CREATE)) != 0) {
1586 		vdev_close(vd);
1587 		return (error);
1588 	}
1589 
1590 	return (0);
1591 }
1592 
1593 void
1594 vdev_metaslab_set_size(vdev_t *vd)
1595 {
1596 	/*
1597 	 * Aim for roughly metaslabs_per_vdev (default 200) metaslabs per vdev.
1598 	 */
1599 	vd->vdev_ms_shift = highbit64(vd->vdev_asize / metaslabs_per_vdev);
1600 	vd->vdev_ms_shift = MAX(vd->vdev_ms_shift, SPA_MAXBLOCKSHIFT);
1601 }
1602 
1603 void
1604 vdev_dirty(vdev_t *vd, int flags, void *arg, uint64_t txg)
1605 {
1606 	ASSERT(vd == vd->vdev_top);
1607 	ASSERT(!vd->vdev_ishole);
1608 	ASSERT(ISP2(flags));
1609 	ASSERT(spa_writeable(vd->vdev_spa));
1610 
1611 	if (flags & VDD_METASLAB)
1612 		(void) txg_list_add(&vd->vdev_ms_list, arg, txg);
1613 
1614 	if (flags & VDD_DTL)
1615 		(void) txg_list_add(&vd->vdev_dtl_list, arg, txg);
1616 
1617 	(void) txg_list_add(&vd->vdev_spa->spa_vdev_txg_list, vd, txg);
1618 }
1619 
1620 void
1621 vdev_dirty_leaves(vdev_t *vd, int flags, uint64_t txg)
1622 {
1623 	for (int c = 0; c < vd->vdev_children; c++)
1624 		vdev_dirty_leaves(vd->vdev_child[c], flags, txg);
1625 
1626 	if (vd->vdev_ops->vdev_op_leaf)
1627 		vdev_dirty(vd->vdev_top, flags, vd, txg);
1628 }
1629 
1630 /*
1631  * DTLs.
1632  *
1633  * A vdev's DTL (dirty time log) is the set of transaction groups for which
1634  * the vdev has less than perfect replication.  There are four kinds of DTL:
1635  *
1636  * DTL_MISSING: txgs for which the vdev has no valid copies of the data
1637  *
1638  * DTL_PARTIAL: txgs for which data is available, but not fully replicated
1639  *
1640  * DTL_SCRUB: the txgs that could not be repaired by the last scrub; upon
1641  *	scrub completion, DTL_SCRUB replaces DTL_MISSING in the range of
1642  *	txgs that was scrubbed.
1643  *
1644  * DTL_OUTAGE: txgs which cannot currently be read, whether due to
1645  *	persistent errors or just some device being offline.
1646  *	Unlike the other three, the DTL_OUTAGE map is not generally
1647  *	maintained; it's only computed when needed, typically to
1648  *	determine whether a device can be detached.
1649  *
1650  * For leaf vdevs, DTL_MISSING and DTL_PARTIAL are identical: the device
1651  * either has the data or it doesn't.
1652  *
1653  * For interior vdevs such as mirror and RAID-Z the picture is more complex.
1654  * A vdev's DTL_PARTIAL is the union of its children's DTL_PARTIALs, because
1655  * if any child is less than fully replicated, then so is its parent.
1656  * A vdev's DTL_MISSING is a modified union of its children's DTL_MISSINGs,
1657  * comprising only those txgs which appear in 'maxfaults' or more children;
1658  * those are the txgs we don't have enough replication to read.  For example,
1659  * double-parity RAID-Z can tolerate up to two missing devices (maxfaults == 2);
1660  * thus, its DTL_MISSING consists of the set of txgs that appear in more than
1661  * two child DTL_MISSING maps.
1662  *
1663  * It should be clear from the above that to compute the DTLs and outage maps
1664  * for all vdevs, it suffices to know just the leaf vdevs' DTL_MISSING maps.
1665  * Therefore, that is all we keep on disk.  When loading the pool, or after
1666  * a configuration change, we generate all other DTLs from first principles.
1667  */
1668 void
1669 vdev_dtl_dirty(vdev_t *vd, vdev_dtl_type_t t, uint64_t txg, uint64_t size)
1670 {
1671 	range_tree_t *rt = vd->vdev_dtl[t];
1672 
1673 	ASSERT(t < DTL_TYPES);
1674 	ASSERT(vd != vd->vdev_spa->spa_root_vdev);
1675 	ASSERT(spa_writeable(vd->vdev_spa));
1676 
1677 	mutex_enter(rt->rt_lock);
1678 	if (!range_tree_contains(rt, txg, size))
1679 		range_tree_add(rt, txg, size);
1680 	mutex_exit(rt->rt_lock);
1681 }
1682 
1683 boolean_t
1684 vdev_dtl_contains(vdev_t *vd, vdev_dtl_type_t t, uint64_t txg, uint64_t size)
1685 {
1686 	range_tree_t *rt = vd->vdev_dtl[t];
1687 	boolean_t dirty = B_FALSE;
1688 
1689 	ASSERT(t < DTL_TYPES);
1690 	ASSERT(vd != vd->vdev_spa->spa_root_vdev);
1691 
1692 	mutex_enter(rt->rt_lock);
1693 	if (range_tree_space(rt) != 0)
1694 		dirty = range_tree_contains(rt, txg, size);
1695 	mutex_exit(rt->rt_lock);
1696 
1697 	return (dirty);
1698 }
1699 
1700 boolean_t
1701 vdev_dtl_empty(vdev_t *vd, vdev_dtl_type_t t)
1702 {
1703 	range_tree_t *rt = vd->vdev_dtl[t];
1704 	boolean_t empty;
1705 
1706 	mutex_enter(rt->rt_lock);
1707 	empty = (range_tree_space(rt) == 0);
1708 	mutex_exit(rt->rt_lock);
1709 
1710 	return (empty);
1711 }
1712 
1713 /*
1714  * Returns the lowest txg in the DTL range.
1715  */
1716 static uint64_t
1717 vdev_dtl_min(vdev_t *vd)
1718 {
1719 	range_seg_t *rs;
1720 
1721 	ASSERT(MUTEX_HELD(&vd->vdev_dtl_lock));
1722 	ASSERT3U(range_tree_space(vd->vdev_dtl[DTL_MISSING]), !=, 0);
1723 	ASSERT0(vd->vdev_children);
1724 
1725 	rs = avl_first(&vd->vdev_dtl[DTL_MISSING]->rt_root);
1726 	return (rs->rs_start - 1);
1727 }
1728 
1729 /*
1730  * Returns the highest txg in the DTL.
1731  */
1732 static uint64_t
1733 vdev_dtl_max(vdev_t *vd)
1734 {
1735 	range_seg_t *rs;
1736 
1737 	ASSERT(MUTEX_HELD(&vd->vdev_dtl_lock));
1738 	ASSERT3U(range_tree_space(vd->vdev_dtl[DTL_MISSING]), !=, 0);
1739 	ASSERT0(vd->vdev_children);
1740 
1741 	rs = avl_last(&vd->vdev_dtl[DTL_MISSING]->rt_root);
1742 	return (rs->rs_end);
1743 }
1744 
1745 /*
1746  * Determine if a resilvering vdev should remove any DTL entries from
1747  * its range. If the vdev was resilvering for the entire duration of the
1748  * scan then it should excise that range from its DTLs. Otherwise, this
1749  * vdev is considered partially resilvered and should leave its DTL
1750  * entries intact. The comment in vdev_dtl_reassess() describes how we
1751  * excise the DTLs.
1752  */
1753 static boolean_t
1754 vdev_dtl_should_excise(vdev_t *vd)
1755 {
1756 	spa_t *spa = vd->vdev_spa;
1757 	dsl_scan_t *scn = spa->spa_dsl_pool->dp_scan;
1758 
1759 	ASSERT0(scn->scn_phys.scn_errors);
1760 	ASSERT0(vd->vdev_children);
1761 
1762 	if (vd->vdev_resilver_txg == 0 ||
1763 	    range_tree_space(vd->vdev_dtl[DTL_MISSING]) == 0)
1764 		return (B_TRUE);
1765 
1766 	/*
1767 	 * When a resilver is initiated the scan will assign the scn_max_txg
1768 	 * value to the highest txg value that exists in all DTLs. If this
1769 	 * device's max DTL is not part of this scan (i.e. it is not in
1770 	 * the range (scn_min_txg, scn_max_txg] then it is not eligible
1771 	 * for excision.
1772 	 */
1773 	if (vdev_dtl_max(vd) <= scn->scn_phys.scn_max_txg) {
1774 		ASSERT3U(scn->scn_phys.scn_min_txg, <=, vdev_dtl_min(vd));
1775 		ASSERT3U(scn->scn_phys.scn_min_txg, <, vd->vdev_resilver_txg);
1776 		ASSERT3U(vd->vdev_resilver_txg, <=, scn->scn_phys.scn_max_txg);
1777 		return (B_TRUE);
1778 	}
1779 	return (B_FALSE);
1780 }
1781 
1782 /*
1783  * Reassess DTLs after a config change or scrub completion.
1784  */
1785 void
1786 vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg, int scrub_done)
1787 {
1788 	spa_t *spa = vd->vdev_spa;
1789 	avl_tree_t reftree;
1790 	int minref;
1791 
1792 	ASSERT(spa_config_held(spa, SCL_ALL, RW_READER) != 0);
1793 
1794 	for (int c = 0; c < vd->vdev_children; c++)
1795 		vdev_dtl_reassess(vd->vdev_child[c], txg,
1796 		    scrub_txg, scrub_done);
1797 
1798 	if (vd == spa->spa_root_vdev || vd->vdev_ishole || vd->vdev_aux)
1799 		return;
1800 
1801 	if (vd->vdev_ops->vdev_op_leaf) {
1802 		dsl_scan_t *scn = spa->spa_dsl_pool->dp_scan;
1803 
1804 		mutex_enter(&vd->vdev_dtl_lock);
1805 
1806 		/*
1807 		 * If we've completed a scan cleanly then determine
1808 		 * if this vdev should remove any DTLs. We only want to
1809 		 * excise regions on vdevs that were available during
1810 		 * the entire duration of this scan.
1811 		 */
1812 		if (scrub_txg != 0 &&
1813 		    (spa->spa_scrub_started ||
1814 		    (scn != NULL && scn->scn_phys.scn_errors == 0)) &&
1815 		    vdev_dtl_should_excise(vd)) {
1816 			/*
1817 			 * We completed a scrub up to scrub_txg.  If we
1818 			 * did it without rebooting, then the scrub dtl
1819 			 * will be valid, so excise the old region and
1820 			 * fold in the scrub dtl.  Otherwise, leave the
1821 			 * dtl as-is if there was an error.
1822 			 *
1823 			 * There's little trick here: to excise the beginning
1824 			 * of the DTL_MISSING map, we put it into a reference
1825 			 * tree and then add a segment with refcnt -1 that
1826 			 * covers the range [0, scrub_txg).  This means
1827 			 * that each txg in that range has refcnt -1 or 0.
1828 			 * We then add DTL_SCRUB with a refcnt of 2, so that
1829 			 * entries in the range [0, scrub_txg) will have a
1830 			 * positive refcnt -- either 1 or 2.  We then convert
1831 			 * the reference tree into the new DTL_MISSING map.
1832 			 */
1833 			space_reftree_create(&reftree);
1834 			space_reftree_add_map(&reftree,
1835 			    vd->vdev_dtl[DTL_MISSING], 1);
1836 			space_reftree_add_seg(&reftree, 0, scrub_txg, -1);
1837 			space_reftree_add_map(&reftree,
1838 			    vd->vdev_dtl[DTL_SCRUB], 2);
1839 			space_reftree_generate_map(&reftree,
1840 			    vd->vdev_dtl[DTL_MISSING], 1);
1841 			space_reftree_destroy(&reftree);
1842 		}
1843 		range_tree_vacate(vd->vdev_dtl[DTL_PARTIAL], NULL, NULL);
1844 		range_tree_walk(vd->vdev_dtl[DTL_MISSING],
1845 		    range_tree_add, vd->vdev_dtl[DTL_PARTIAL]);
1846 		if (scrub_done)
1847 			range_tree_vacate(vd->vdev_dtl[DTL_SCRUB], NULL, NULL);
1848 		range_tree_vacate(vd->vdev_dtl[DTL_OUTAGE], NULL, NULL);
1849 		if (!vdev_readable(vd))
1850 			range_tree_add(vd->vdev_dtl[DTL_OUTAGE], 0, -1ULL);
1851 		else
1852 			range_tree_walk(vd->vdev_dtl[DTL_MISSING],
1853 			    range_tree_add, vd->vdev_dtl[DTL_OUTAGE]);
1854 
1855 		/*
1856 		 * If the vdev was resilvering and no longer has any
1857 		 * DTLs then reset its resilvering flag.
1858 		 */
1859 		if (vd->vdev_resilver_txg != 0 &&
1860 		    range_tree_space(vd->vdev_dtl[DTL_MISSING]) == 0 &&
1861 		    range_tree_space(vd->vdev_dtl[DTL_OUTAGE]) == 0)
1862 			vd->vdev_resilver_txg = 0;
1863 
1864 		mutex_exit(&vd->vdev_dtl_lock);
1865 
1866 		if (txg != 0)
1867 			vdev_dirty(vd->vdev_top, VDD_DTL, vd, txg);
1868 		return;
1869 	}
1870 
1871 	mutex_enter(&vd->vdev_dtl_lock);
1872 	for (int t = 0; t < DTL_TYPES; t++) {
1873 		/* account for child's outage in parent's missing map */
1874 		int s = (t == DTL_MISSING) ? DTL_OUTAGE: t;
1875 		if (t == DTL_SCRUB)
1876 			continue;			/* leaf vdevs only */
1877 		if (t == DTL_PARTIAL)
1878 			minref = 1;			/* i.e. non-zero */
1879 		else if (vd->vdev_nparity != 0)
1880 			minref = vd->vdev_nparity + 1;	/* RAID-Z */
1881 		else
1882 			minref = vd->vdev_children;	/* any kind of mirror */
1883 		space_reftree_create(&reftree);
1884 		for (int c = 0; c < vd->vdev_children; c++) {
1885 			vdev_t *cvd = vd->vdev_child[c];
1886 			mutex_enter(&cvd->vdev_dtl_lock);
1887 			space_reftree_add_map(&reftree, cvd->vdev_dtl[s], 1);
1888 			mutex_exit(&cvd->vdev_dtl_lock);
1889 		}
1890 		space_reftree_generate_map(&reftree, vd->vdev_dtl[t], minref);
1891 		space_reftree_destroy(&reftree);
1892 	}
1893 	mutex_exit(&vd->vdev_dtl_lock);
1894 }
1895 
1896 int
1897 vdev_dtl_load(vdev_t *vd)
1898 {
1899 	spa_t *spa = vd->vdev_spa;
1900 	objset_t *mos = spa->spa_meta_objset;
1901 	int error = 0;
1902 
1903 	if (vd->vdev_ops->vdev_op_leaf && vd->vdev_dtl_object != 0) {
1904 		ASSERT(!vd->vdev_ishole);
1905 
1906 		error = space_map_open(&vd->vdev_dtl_sm, mos,
1907 		    vd->vdev_dtl_object, 0, -1ULL, 0, &vd->vdev_dtl_lock);
1908 		if (error)
1909 			return (error);
1910 		ASSERT(vd->vdev_dtl_sm != NULL);
1911 
1912 		mutex_enter(&vd->vdev_dtl_lock);
1913 
1914 		/*
1915 		 * Now that we've opened the space_map we need to update
1916 		 * the in-core DTL.
1917 		 */
1918 		space_map_update(vd->vdev_dtl_sm);
1919 
1920 		error = space_map_load(vd->vdev_dtl_sm,
1921 		    vd->vdev_dtl[DTL_MISSING], SM_ALLOC);
1922 		mutex_exit(&vd->vdev_dtl_lock);
1923 
1924 		return (error);
1925 	}
1926 
1927 	for (int c = 0; c < vd->vdev_children; c++) {
1928 		error = vdev_dtl_load(vd->vdev_child[c]);
1929 		if (error != 0)
1930 			break;
1931 	}
1932 
1933 	return (error);
1934 }
1935 
1936 void
1937 vdev_dtl_sync(vdev_t *vd, uint64_t txg)
1938 {
1939 	spa_t *spa = vd->vdev_spa;
1940 	range_tree_t *rt = vd->vdev_dtl[DTL_MISSING];
1941 	objset_t *mos = spa->spa_meta_objset;
1942 	range_tree_t *rtsync;
1943 	kmutex_t rtlock;
1944 	dmu_tx_t *tx;
1945 	uint64_t object = space_map_object(vd->vdev_dtl_sm);
1946 
1947 	ASSERT(!vd->vdev_ishole);
1948 	ASSERT(vd->vdev_ops->vdev_op_leaf);
1949 
1950 	tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
1951 
1952 	if (vd->vdev_detached || vd->vdev_top->vdev_removing) {
1953 		mutex_enter(&vd->vdev_dtl_lock);
1954 		space_map_free(vd->vdev_dtl_sm, tx);
1955 		space_map_close(vd->vdev_dtl_sm);
1956 		vd->vdev_dtl_sm = NULL;
1957 		mutex_exit(&vd->vdev_dtl_lock);
1958 		dmu_tx_commit(tx);
1959 		return;
1960 	}
1961 
1962 	if (vd->vdev_dtl_sm == NULL) {
1963 		uint64_t new_object;
1964 
1965 		new_object = space_map_alloc(mos, tx);
1966 		VERIFY3U(new_object, !=, 0);
1967 
1968 		VERIFY0(space_map_open(&vd->vdev_dtl_sm, mos, new_object,
1969 		    0, -1ULL, 0, &vd->vdev_dtl_lock));
1970 		ASSERT(vd->vdev_dtl_sm != NULL);
1971 	}
1972 
1973 	mutex_init(&rtlock, NULL, MUTEX_DEFAULT, NULL);
1974 
1975 	rtsync = range_tree_create(NULL, NULL, &rtlock);
1976 
1977 	mutex_enter(&rtlock);
1978 
1979 	mutex_enter(&vd->vdev_dtl_lock);
1980 	range_tree_walk(rt, range_tree_add, rtsync);
1981 	mutex_exit(&vd->vdev_dtl_lock);
1982 
1983 	space_map_truncate(vd->vdev_dtl_sm, tx);
1984 	space_map_write(vd->vdev_dtl_sm, rtsync, SM_ALLOC, tx);
1985 	range_tree_vacate(rtsync, NULL, NULL);
1986 
1987 	range_tree_destroy(rtsync);
1988 
1989 	mutex_exit(&rtlock);
1990 	mutex_destroy(&rtlock);
1991 
1992 	/*
1993 	 * If the object for the space map has changed then dirty
1994 	 * the top level so that we update the config.
1995 	 */
1996 	if (object != space_map_object(vd->vdev_dtl_sm)) {
1997 		zfs_dbgmsg("txg %llu, spa %s, DTL old object %llu, "
1998 		    "new object %llu", txg, spa_name(spa), object,
1999 		    space_map_object(vd->vdev_dtl_sm));
2000 		vdev_config_dirty(vd->vdev_top);
2001 	}
2002 
2003 	dmu_tx_commit(tx);
2004 
2005 	mutex_enter(&vd->vdev_dtl_lock);
2006 	space_map_update(vd->vdev_dtl_sm);
2007 	mutex_exit(&vd->vdev_dtl_lock);
2008 }
2009 
2010 /*
2011  * Determine whether the specified vdev can be offlined/detached/removed
2012  * without losing data.
2013  */
2014 boolean_t
2015 vdev_dtl_required(vdev_t *vd)
2016 {
2017 	spa_t *spa = vd->vdev_spa;
2018 	vdev_t *tvd = vd->vdev_top;
2019 	uint8_t cant_read = vd->vdev_cant_read;
2020 	boolean_t required;
2021 
2022 	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
2023 
2024 	if (vd == spa->spa_root_vdev || vd == tvd)
2025 		return (B_TRUE);
2026 
2027 	/*
2028 	 * Temporarily mark the device as unreadable, and then determine
2029 	 * whether this results in any DTL outages in the top-level vdev.
2030 	 * If not, we can safely offline/detach/remove the device.
2031 	 */
2032 	vd->vdev_cant_read = B_TRUE;
2033 	vdev_dtl_reassess(tvd, 0, 0, B_FALSE);
2034 	required = !vdev_dtl_empty(tvd, DTL_OUTAGE);
2035 	vd->vdev_cant_read = cant_read;
2036 	vdev_dtl_reassess(tvd, 0, 0, B_FALSE);
2037 
2038 	if (!required && zio_injection_enabled)
2039 		required = !!zio_handle_device_injection(vd, NULL, ECHILD);
2040 
2041 	return (required);
2042 }
2043 
2044 /*
2045  * Determine if resilver is needed, and if so the txg range.
2046  */
2047 boolean_t
2048 vdev_resilver_needed(vdev_t *vd, uint64_t *minp, uint64_t *maxp)
2049 {
2050 	boolean_t needed = B_FALSE;
2051 	uint64_t thismin = UINT64_MAX;
2052 	uint64_t thismax = 0;
2053 
2054 	if (vd->vdev_children == 0) {
2055 		mutex_enter(&vd->vdev_dtl_lock);
2056 		if (range_tree_space(vd->vdev_dtl[DTL_MISSING]) != 0 &&
2057 		    vdev_writeable(vd)) {
2058 
2059 			thismin = vdev_dtl_min(vd);
2060 			thismax = vdev_dtl_max(vd);
2061 			needed = B_TRUE;
2062 		}
2063 		mutex_exit(&vd->vdev_dtl_lock);
2064 	} else {
2065 		for (int c = 0; c < vd->vdev_children; c++) {
2066 			vdev_t *cvd = vd->vdev_child[c];
2067 			uint64_t cmin, cmax;
2068 
2069 			if (vdev_resilver_needed(cvd, &cmin, &cmax)) {
2070 				thismin = MIN(thismin, cmin);
2071 				thismax = MAX(thismax, cmax);
2072 				needed = B_TRUE;
2073 			}
2074 		}
2075 	}
2076 
2077 	if (needed && minp) {
2078 		*minp = thismin;
2079 		*maxp = thismax;
2080 	}
2081 	return (needed);
2082 }
2083 
2084 void
2085 vdev_load(vdev_t *vd)
2086 {
2087 	/*
2088 	 * Recursively load all children.
2089 	 */
2090 	for (int c = 0; c < vd->vdev_children; c++)
2091 		vdev_load(vd->vdev_child[c]);
2092 
2093 	/*
2094 	 * If this is a top-level vdev, initialize its metaslabs.
2095 	 */
2096 	if (vd == vd->vdev_top && !vd->vdev_ishole &&
2097 	    (vd->vdev_ashift == 0 || vd->vdev_asize == 0 ||
2098 	    vdev_metaslab_init(vd, 0) != 0))
2099 		vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
2100 		    VDEV_AUX_CORRUPT_DATA);
2101 
2102 	/*
2103 	 * If this is a leaf vdev, load its DTL.
2104 	 */
2105 	if (vd->vdev_ops->vdev_op_leaf && vdev_dtl_load(vd) != 0)
2106 		vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
2107 		    VDEV_AUX_CORRUPT_DATA);
2108 }
2109 
2110 /*
2111  * The special vdev case is used for hot spares and l2cache devices.  Its
2112  * sole purpose it to set the vdev state for the associated vdev.  To do this,
2113  * we make sure that we can open the underlying device, then try to read the
2114  * label, and make sure that the label is sane and that it hasn't been
2115  * repurposed to another pool.
2116  */
2117 int
2118 vdev_validate_aux(vdev_t *vd)
2119 {
2120 	nvlist_t *label;
2121 	uint64_t guid, version;
2122 	uint64_t state;
2123 
2124 	if (!vdev_readable(vd))
2125 		return (0);
2126 
2127 	if ((label = vdev_label_read_config(vd, -1ULL)) == NULL) {
2128 		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
2129 		    VDEV_AUX_CORRUPT_DATA);
2130 		return (-1);
2131 	}
2132 
2133 	if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_VERSION, &version) != 0 ||
2134 	    !SPA_VERSION_IS_SUPPORTED(version) ||
2135 	    nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID, &guid) != 0 ||
2136 	    guid != vd->vdev_guid ||
2137 	    nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE, &state) != 0) {
2138 		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
2139 		    VDEV_AUX_CORRUPT_DATA);
2140 		nvlist_free(label);
2141 		return (-1);
2142 	}
2143 
2144 	/*
2145 	 * We don't actually check the pool state here.  If it's in fact in
2146 	 * use by another pool, we update this fact on the fly when requested.
2147 	 */
2148 	nvlist_free(label);
2149 	return (0);
2150 }
2151 
2152 void
2153 vdev_remove(vdev_t *vd, uint64_t txg)
2154 {
2155 	spa_t *spa = vd->vdev_spa;
2156 	objset_t *mos = spa->spa_meta_objset;
2157 	dmu_tx_t *tx;
2158 
2159 	tx = dmu_tx_create_assigned(spa_get_dsl(spa), txg);
2160 
2161 	if (vd->vdev_ms != NULL) {
2162 		metaslab_group_t *mg = vd->vdev_mg;
2163 
2164 		metaslab_group_histogram_verify(mg);
2165 		metaslab_class_histogram_verify(mg->mg_class);
2166 
2167 		for (int m = 0; m < vd->vdev_ms_count; m++) {
2168 			metaslab_t *msp = vd->vdev_ms[m];
2169 
2170 			if (msp == NULL || msp->ms_sm == NULL)
2171 				continue;
2172 
2173 			mutex_enter(&msp->ms_lock);
2174 			/*
2175 			 * If the metaslab was not loaded when the vdev
2176 			 * was removed then the histogram accounting may
2177 			 * not be accurate. Update the histogram information
2178 			 * here so that we ensure that the metaslab group
2179 			 * and metaslab class are up-to-date.
2180 			 */
2181 			metaslab_group_histogram_remove(mg, msp);
2182 
2183 			VERIFY0(space_map_allocated(msp->ms_sm));
2184 			space_map_free(msp->ms_sm, tx);
2185 			space_map_close(msp->ms_sm);
2186 			msp->ms_sm = NULL;
2187 			mutex_exit(&msp->ms_lock);
2188 		}
2189 
2190 		metaslab_group_histogram_verify(mg);
2191 		metaslab_class_histogram_verify(mg->mg_class);
2192 		for (int i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i++)
2193 			ASSERT0(mg->mg_histogram[i]);
2194 
2195 	}
2196 
2197 	if (vd->vdev_ms_array) {
2198 		(void) dmu_object_free(mos, vd->vdev_ms_array, tx);
2199 		vd->vdev_ms_array = 0;
2200 	}
2201 	dmu_tx_commit(tx);
2202 }
2203 
2204 void
2205 vdev_sync_done(vdev_t *vd, uint64_t txg)
2206 {
2207 	metaslab_t *msp;
2208 	boolean_t reassess = !txg_list_empty(&vd->vdev_ms_list, TXG_CLEAN(txg));
2209 
2210 	ASSERT(!vd->vdev_ishole);
2211 
2212 	while (msp = txg_list_remove(&vd->vdev_ms_list, TXG_CLEAN(txg)))
2213 		metaslab_sync_done(msp, txg);
2214 
2215 	if (reassess)
2216 		metaslab_sync_reassess(vd->vdev_mg);
2217 }
2218 
2219 void
2220 vdev_sync(vdev_t *vd, uint64_t txg)
2221 {
2222 	spa_t *spa = vd->vdev_spa;
2223 	vdev_t *lvd;
2224 	metaslab_t *msp;
2225 	dmu_tx_t *tx;
2226 
2227 	ASSERT(!vd->vdev_ishole);
2228 
2229 	if (vd->vdev_ms_array == 0 && vd->vdev_ms_shift != 0) {
2230 		ASSERT(vd == vd->vdev_top);
2231 		tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
2232 		vd->vdev_ms_array = dmu_object_alloc(spa->spa_meta_objset,
2233 		    DMU_OT_OBJECT_ARRAY, 0, DMU_OT_NONE, 0, tx);
2234 		ASSERT(vd->vdev_ms_array != 0);
2235 		vdev_config_dirty(vd);
2236 		dmu_tx_commit(tx);
2237 	}
2238 
2239 	/*
2240 	 * Remove the metadata associated with this vdev once it's empty.
2241 	 */
2242 	if (vd->vdev_stat.vs_alloc == 0 && vd->vdev_removing)
2243 		vdev_remove(vd, txg);
2244 
2245 	while ((msp = txg_list_remove(&vd->vdev_ms_list, txg)) != NULL) {
2246 		metaslab_sync(msp, txg);
2247 		(void) txg_list_add(&vd->vdev_ms_list, msp, TXG_CLEAN(txg));
2248 	}
2249 
2250 	while ((lvd = txg_list_remove(&vd->vdev_dtl_list, txg)) != NULL)
2251 		vdev_dtl_sync(lvd, txg);
2252 
2253 	(void) txg_list_add(&spa->spa_vdev_txg_list, vd, TXG_CLEAN(txg));
2254 }
2255 
2256 uint64_t
2257 vdev_psize_to_asize(vdev_t *vd, uint64_t psize)
2258 {
2259 	return (vd->vdev_ops->vdev_op_asize(vd, psize));
2260 }
2261 
2262 /*
2263  * Mark the given vdev faulted.  A faulted vdev behaves as if the device could
2264  * not be opened, and no I/O is attempted.
2265  */
2266 int
2267 vdev_fault(spa_t *spa, uint64_t guid, vdev_aux_t aux)
2268 {
2269 	vdev_t *vd, *tvd;
2270 
2271 	spa_vdev_state_enter(spa, SCL_NONE);
2272 
2273 	if ((vd = spa_lookup_by_guid(spa, guid, B_TRUE)) == NULL)
2274 		return (spa_vdev_state_exit(spa, NULL, ENODEV));
2275 
2276 	if (!vd->vdev_ops->vdev_op_leaf)
2277 		return (spa_vdev_state_exit(spa, NULL, ENOTSUP));
2278 
2279 	tvd = vd->vdev_top;
2280 
2281 	/*
2282 	 * We don't directly use the aux state here, but if we do a
2283 	 * vdev_reopen(), we need this value to be present to remember why we
2284 	 * were faulted.
2285 	 */
2286 	vd->vdev_label_aux = aux;
2287 
2288 	/*
2289 	 * Faulted state takes precedence over degraded.
2290 	 */
2291 	vd->vdev_delayed_close = B_FALSE;
2292 	vd->vdev_faulted = 1ULL;
2293 	vd->vdev_degraded = 0ULL;
2294 	vdev_set_state(vd, B_FALSE, VDEV_STATE_FAULTED, aux);
2295 
2296 	/*
2297 	 * If this device has the only valid copy of the data, then
2298 	 * back off and simply mark the vdev as degraded instead.
2299 	 */
2300 	if (!tvd->vdev_islog && vd->vdev_aux == NULL && vdev_dtl_required(vd)) {
2301 		vd->vdev_degraded = 1ULL;
2302 		vd->vdev_faulted = 0ULL;
2303 
2304 		/*
2305 		 * If we reopen the device and it's not dead, only then do we
2306 		 * mark it degraded.
2307 		 */
2308 		vdev_reopen(tvd);
2309 
2310 		if (vdev_readable(vd))
2311 			vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, aux);
2312 	}
2313 
2314 	return (spa_vdev_state_exit(spa, vd, 0));
2315 }
2316 
2317 /*
2318  * Mark the given vdev degraded.  A degraded vdev is purely an indication to the
2319  * user that something is wrong.  The vdev continues to operate as normal as far
2320  * as I/O is concerned.
2321  */
2322 int
2323 vdev_degrade(spa_t *spa, uint64_t guid, vdev_aux_t aux)
2324 {
2325 	vdev_t *vd;
2326 
2327 	spa_vdev_state_enter(spa, SCL_NONE);
2328 
2329 	if ((vd = spa_lookup_by_guid(spa, guid, B_TRUE)) == NULL)
2330 		return (spa_vdev_state_exit(spa, NULL, ENODEV));
2331 
2332 	if (!vd->vdev_ops->vdev_op_leaf)
2333 		return (spa_vdev_state_exit(spa, NULL, ENOTSUP));
2334 
2335 	/*
2336 	 * If the vdev is already faulted, then don't do anything.
2337 	 */
2338 	if (vd->vdev_faulted || vd->vdev_degraded)
2339 		return (spa_vdev_state_exit(spa, NULL, 0));
2340 
2341 	vd->vdev_degraded = 1ULL;
2342 	if (!vdev_is_dead(vd))
2343 		vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED,
2344 		    aux);
2345 
2346 	return (spa_vdev_state_exit(spa, vd, 0));
2347 }
2348 
2349 /*
2350  * Online the given vdev.
2351  *
2352  * If 'ZFS_ONLINE_UNSPARE' is set, it implies two things.  First, any attached
2353  * spare device should be detached when the device finishes resilvering.
2354  * Second, the online should be treated like a 'test' online case, so no FMA
2355  * events are generated if the device fails to open.
2356  */
2357 int
2358 vdev_online(spa_t *spa, uint64_t guid, uint64_t flags, vdev_state_t *newstate)
2359 {
2360 	vdev_t *vd, *tvd, *pvd, *rvd = spa->spa_root_vdev;
2361 	boolean_t postevent = B_FALSE;
2362 
2363 	spa_vdev_state_enter(spa, SCL_NONE);
2364 
2365 	if ((vd = spa_lookup_by_guid(spa, guid, B_TRUE)) == NULL)
2366 		return (spa_vdev_state_exit(spa, NULL, ENODEV));
2367 
2368 	if (!vd->vdev_ops->vdev_op_leaf)
2369 		return (spa_vdev_state_exit(spa, NULL, ENOTSUP));
2370 
2371 	postevent =
2372 	    (vd->vdev_offline == B_TRUE || vd->vdev_tmpoffline == B_TRUE) ?
2373 	    B_TRUE : B_FALSE;
2374 
2375 	tvd = vd->vdev_top;
2376 	vd->vdev_offline = B_FALSE;
2377 	vd->vdev_tmpoffline = B_FALSE;
2378 	vd->vdev_checkremove = !!(flags & ZFS_ONLINE_CHECKREMOVE);
2379 	vd->vdev_forcefault = !!(flags & ZFS_ONLINE_FORCEFAULT);
2380 
2381 	/* XXX - L2ARC 1.0 does not support expansion */
2382 	if (!vd->vdev_aux) {
2383 		for (pvd = vd; pvd != rvd; pvd = pvd->vdev_parent)
2384 			pvd->vdev_expanding = !!(flags & ZFS_ONLINE_EXPAND);
2385 	}
2386 
2387 	vdev_reopen(tvd);
2388 	vd->vdev_checkremove = vd->vdev_forcefault = B_FALSE;
2389 
2390 	if (!vd->vdev_aux) {
2391 		for (pvd = vd; pvd != rvd; pvd = pvd->vdev_parent)
2392 			pvd->vdev_expanding = B_FALSE;
2393 	}
2394 
2395 	if (newstate)
2396 		*newstate = vd->vdev_state;
2397 	if ((flags & ZFS_ONLINE_UNSPARE) &&
2398 	    !vdev_is_dead(vd) && vd->vdev_parent &&
2399 	    vd->vdev_parent->vdev_ops == &vdev_spare_ops &&
2400 	    vd->vdev_parent->vdev_child[0] == vd)
2401 		vd->vdev_unspare = B_TRUE;
2402 
2403 	if ((flags & ZFS_ONLINE_EXPAND) || spa->spa_autoexpand) {
2404 
2405 		/* XXX - L2ARC 1.0 does not support expansion */
2406 		if (vd->vdev_aux)
2407 			return (spa_vdev_state_exit(spa, vd, ENOTSUP));
2408 		spa_async_request(spa, SPA_ASYNC_CONFIG_UPDATE);
2409 	}
2410 
2411 	if (postevent)
2412 		spa_event_notify(spa, vd, ESC_ZFS_VDEV_ONLINE);
2413 
2414 	return (spa_vdev_state_exit(spa, vd, 0));
2415 }
2416 
2417 static int
2418 vdev_offline_locked(spa_t *spa, uint64_t guid, uint64_t flags)
2419 {
2420 	vdev_t *vd, *tvd;
2421 	int error = 0;
2422 	uint64_t generation;
2423 	metaslab_group_t *mg;
2424 
2425 top:
2426 	spa_vdev_state_enter(spa, SCL_ALLOC);
2427 
2428 	if ((vd = spa_lookup_by_guid(spa, guid, B_TRUE)) == NULL)
2429 		return (spa_vdev_state_exit(spa, NULL, ENODEV));
2430 
2431 	if (!vd->vdev_ops->vdev_op_leaf)
2432 		return (spa_vdev_state_exit(spa, NULL, ENOTSUP));
2433 
2434 	tvd = vd->vdev_top;
2435 	mg = tvd->vdev_mg;
2436 	generation = spa->spa_config_generation + 1;
2437 
2438 	/*
2439 	 * If the device isn't already offline, try to offline it.
2440 	 */
2441 	if (!vd->vdev_offline) {
2442 		/*
2443 		 * If this device has the only valid copy of some data,
2444 		 * don't allow it to be offlined. Log devices are always
2445 		 * expendable.
2446 		 */
2447 		if (!tvd->vdev_islog && vd->vdev_aux == NULL &&
2448 		    vdev_dtl_required(vd))
2449 			return (spa_vdev_state_exit(spa, NULL, EBUSY));
2450 
2451 		/*
2452 		 * If the top-level is a slog and it has had allocations
2453 		 * then proceed.  We check that the vdev's metaslab group
2454 		 * is not NULL since it's possible that we may have just
2455 		 * added this vdev but not yet initialized its metaslabs.
2456 		 */
2457 		if (tvd->vdev_islog && mg != NULL) {
2458 			/*
2459 			 * Prevent any future allocations.
2460 			 */
2461 			metaslab_group_passivate(mg);
2462 			(void) spa_vdev_state_exit(spa, vd, 0);
2463 
2464 			error = spa_offline_log(spa);
2465 
2466 			spa_vdev_state_enter(spa, SCL_ALLOC);
2467 
2468 			/*
2469 			 * Check to see if the config has changed.
2470 			 */
2471 			if (error || generation != spa->spa_config_generation) {
2472 				metaslab_group_activate(mg);
2473 				if (error)
2474 					return (spa_vdev_state_exit(spa,
2475 					    vd, error));
2476 				(void) spa_vdev_state_exit(spa, vd, 0);
2477 				goto top;
2478 			}
2479 			ASSERT0(tvd->vdev_stat.vs_alloc);
2480 		}
2481 
2482 		/*
2483 		 * Offline this device and reopen its top-level vdev.
2484 		 * If the top-level vdev is a log device then just offline
2485 		 * it. Otherwise, if this action results in the top-level
2486 		 * vdev becoming unusable, undo it and fail the request.
2487 		 */
2488 		vd->vdev_offline = B_TRUE;
2489 		vdev_reopen(tvd);
2490 
2491 		if (!tvd->vdev_islog && vd->vdev_aux == NULL &&
2492 		    vdev_is_dead(tvd)) {
2493 			vd->vdev_offline = B_FALSE;
2494 			vdev_reopen(tvd);
2495 			return (spa_vdev_state_exit(spa, NULL, EBUSY));
2496 		}
2497 
2498 		/*
2499 		 * Add the device back into the metaslab rotor so that
2500 		 * once we online the device it's open for business.
2501 		 */
2502 		if (tvd->vdev_islog && mg != NULL)
2503 			metaslab_group_activate(mg);
2504 	}
2505 
2506 	vd->vdev_tmpoffline = !!(flags & ZFS_OFFLINE_TEMPORARY);
2507 
2508 	return (spa_vdev_state_exit(spa, vd, 0));
2509 }
2510 
2511 int
2512 vdev_offline(spa_t *spa, uint64_t guid, uint64_t flags)
2513 {
2514 	int error;
2515 
2516 	mutex_enter(&spa->spa_vdev_top_lock);
2517 	error = vdev_offline_locked(spa, guid, flags);
2518 	mutex_exit(&spa->spa_vdev_top_lock);
2519 
2520 	return (error);
2521 }
2522 
2523 /*
2524  * Clear the error counts associated with this vdev.  Unlike vdev_online() and
2525  * vdev_offline(), we assume the spa config is locked.  We also clear all
2526  * children.  If 'vd' is NULL, then the user wants to clear all vdevs.
2527  */
2528 void
2529 vdev_clear(spa_t *spa, vdev_t *vd)
2530 {
2531 	vdev_t *rvd = spa->spa_root_vdev;
2532 
2533 	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
2534 
2535 	if (vd == NULL)
2536 		vd = rvd;
2537 
2538 	vd->vdev_stat.vs_read_errors = 0;
2539 	vd->vdev_stat.vs_write_errors = 0;
2540 	vd->vdev_stat.vs_checksum_errors = 0;
2541 
2542 	for (int c = 0; c < vd->vdev_children; c++)
2543 		vdev_clear(spa, vd->vdev_child[c]);
2544 
2545 	/*
2546 	 * If we're in the FAULTED state or have experienced failed I/O, then
2547 	 * clear the persistent state and attempt to reopen the device.  We
2548 	 * also mark the vdev config dirty, so that the new faulted state is
2549 	 * written out to disk.
2550 	 */
2551 	if (vd->vdev_faulted || vd->vdev_degraded ||
2552 	    !vdev_readable(vd) || !vdev_writeable(vd)) {
2553 
2554 		/*
2555 		 * When reopening in reponse to a clear event, it may be due to
2556 		 * a fmadm repair request.  In this case, if the device is
2557 		 * still broken, we want to still post the ereport again.
2558 		 */
2559 		vd->vdev_forcefault = B_TRUE;
2560 
2561 		vd->vdev_faulted = vd->vdev_degraded = 0ULL;
2562 		vd->vdev_cant_read = B_FALSE;
2563 		vd->vdev_cant_write = B_FALSE;
2564 
2565 		vdev_reopen(vd == rvd ? rvd : vd->vdev_top);
2566 
2567 		vd->vdev_forcefault = B_FALSE;
2568 
2569 		if (vd != rvd && vdev_writeable(vd->vdev_top))
2570 			vdev_state_dirty(vd->vdev_top);
2571 
2572 		if (vd->vdev_aux == NULL && !vdev_is_dead(vd))
2573 			spa_async_request(spa, SPA_ASYNC_RESILVER);
2574 
2575 		spa_event_notify(spa, vd, ESC_ZFS_VDEV_CLEAR);
2576 	}
2577 
2578 	/*
2579 	 * When clearing a FMA-diagnosed fault, we always want to
2580 	 * unspare the device, as we assume that the original spare was
2581 	 * done in response to the FMA fault.
2582 	 */
2583 	if (!vdev_is_dead(vd) && vd->vdev_parent != NULL &&
2584 	    vd->vdev_parent->vdev_ops == &vdev_spare_ops &&
2585 	    vd->vdev_parent->vdev_child[0] == vd)
2586 		vd->vdev_unspare = B_TRUE;
2587 }
2588 
2589 boolean_t
2590 vdev_is_dead(vdev_t *vd)
2591 {
2592 	/*
2593 	 * Holes and missing devices are always considered "dead".
2594 	 * This simplifies the code since we don't have to check for
2595 	 * these types of devices in the various code paths.
2596 	 * Instead we rely on the fact that we skip over dead devices
2597 	 * before issuing I/O to them.
2598 	 */
2599 	return (vd->vdev_state < VDEV_STATE_DEGRADED || vd->vdev_ishole ||
2600 	    vd->vdev_ops == &vdev_missing_ops);
2601 }
2602 
2603 boolean_t
2604 vdev_readable(vdev_t *vd)
2605 {
2606 	return (!vdev_is_dead(vd) && !vd->vdev_cant_read);
2607 }
2608 
2609 boolean_t
2610 vdev_writeable(vdev_t *vd)
2611 {
2612 	return (!vdev_is_dead(vd) && !vd->vdev_cant_write);
2613 }
2614 
2615 boolean_t
2616 vdev_allocatable(vdev_t *vd)
2617 {
2618 	uint64_t state = vd->vdev_state;
2619 
2620 	/*
2621 	 * We currently allow allocations from vdevs which may be in the
2622 	 * process of reopening (i.e. VDEV_STATE_CLOSED). If the device
2623 	 * fails to reopen then we'll catch it later when we're holding
2624 	 * the proper locks.  Note that we have to get the vdev state
2625 	 * in a local variable because although it changes atomically,
2626 	 * we're asking two separate questions about it.
2627 	 */
2628 	return (!(state < VDEV_STATE_DEGRADED && state != VDEV_STATE_CLOSED) &&
2629 	    !vd->vdev_cant_write && !vd->vdev_ishole);
2630 }
2631 
2632 boolean_t
2633 vdev_accessible(vdev_t *vd, zio_t *zio)
2634 {
2635 	ASSERT(zio->io_vd == vd);
2636 
2637 	if (vdev_is_dead(vd) || vd->vdev_remove_wanted)
2638 		return (B_FALSE);
2639 
2640 	if (zio->io_type == ZIO_TYPE_READ)
2641 		return (!vd->vdev_cant_read);
2642 
2643 	if (zio->io_type == ZIO_TYPE_WRITE)
2644 		return (!vd->vdev_cant_write);
2645 
2646 	return (B_TRUE);
2647 }
2648 
2649 /*
2650  * Get statistics for the given vdev.
2651  */
2652 void
2653 vdev_get_stats(vdev_t *vd, vdev_stat_t *vs)
2654 {
2655 	spa_t *spa = vd->vdev_spa;
2656 	vdev_t *rvd = spa->spa_root_vdev;
2657 
2658 	ASSERT(spa_config_held(spa, SCL_ALL, RW_READER) != 0);
2659 
2660 	mutex_enter(&vd->vdev_stat_lock);
2661 	bcopy(&vd->vdev_stat, vs, sizeof (*vs));
2662 	vs->vs_timestamp = gethrtime() - vs->vs_timestamp;
2663 	vs->vs_state = vd->vdev_state;
2664 	vs->vs_rsize = vdev_get_min_asize(vd);
2665 	if (vd->vdev_ops->vdev_op_leaf)
2666 		vs->vs_rsize += VDEV_LABEL_START_SIZE + VDEV_LABEL_END_SIZE;
2667 	vs->vs_esize = vd->vdev_max_asize - vd->vdev_asize;
2668 	if (vd->vdev_aux == NULL && vd == vd->vdev_top && !vd->vdev_ishole) {
2669 		vs->vs_fragmentation = vd->vdev_mg->mg_fragmentation;
2670 	}
2671 
2672 	/*
2673 	 * If we're getting stats on the root vdev, aggregate the I/O counts
2674 	 * over all top-level vdevs (i.e. the direct children of the root).
2675 	 */
2676 	if (vd == rvd) {
2677 		for (int c = 0; c < rvd->vdev_children; c++) {
2678 			vdev_t *cvd = rvd->vdev_child[c];
2679 			vdev_stat_t *cvs = &cvd->vdev_stat;
2680 
2681 			for (int t = 0; t < ZIO_TYPES; t++) {
2682 				vs->vs_ops[t] += cvs->vs_ops[t];
2683 				vs->vs_bytes[t] += cvs->vs_bytes[t];
2684 			}
2685 			cvs->vs_scan_removing = cvd->vdev_removing;
2686 		}
2687 	}
2688 	mutex_exit(&vd->vdev_stat_lock);
2689 }
2690 
2691 void
2692 vdev_clear_stats(vdev_t *vd)
2693 {
2694 	mutex_enter(&vd->vdev_stat_lock);
2695 	vd->vdev_stat.vs_space = 0;
2696 	vd->vdev_stat.vs_dspace = 0;
2697 	vd->vdev_stat.vs_alloc = 0;
2698 	mutex_exit(&vd->vdev_stat_lock);
2699 }
2700 
2701 void
2702 vdev_scan_stat_init(vdev_t *vd)
2703 {
2704 	vdev_stat_t *vs = &vd->vdev_stat;
2705 
2706 	for (int c = 0; c < vd->vdev_children; c++)
2707 		vdev_scan_stat_init(vd->vdev_child[c]);
2708 
2709 	mutex_enter(&vd->vdev_stat_lock);
2710 	vs->vs_scan_processed = 0;
2711 	mutex_exit(&vd->vdev_stat_lock);
2712 }
2713 
2714 void
2715 vdev_stat_update(zio_t *zio, uint64_t psize)
2716 {
2717 	spa_t *spa = zio->io_spa;
2718 	vdev_t *rvd = spa->spa_root_vdev;
2719 	vdev_t *vd = zio->io_vd ? zio->io_vd : rvd;
2720 	vdev_t *pvd;
2721 	uint64_t txg = zio->io_txg;
2722 	vdev_stat_t *vs = &vd->vdev_stat;
2723 	zio_type_t type = zio->io_type;
2724 	int flags = zio->io_flags;
2725 
2726 	/*
2727 	 * If this i/o is a gang leader, it didn't do any actual work.
2728 	 */
2729 	if (zio->io_gang_tree)
2730 		return;
2731 
2732 	if (zio->io_error == 0) {
2733 		/*
2734 		 * If this is a root i/o, don't count it -- we've already
2735 		 * counted the top-level vdevs, and vdev_get_stats() will
2736 		 * aggregate them when asked.  This reduces contention on
2737 		 * the root vdev_stat_lock and implicitly handles blocks
2738 		 * that compress away to holes, for which there is no i/o.
2739 		 * (Holes never create vdev children, so all the counters
2740 		 * remain zero, which is what we want.)
2741 		 *
2742 		 * Note: this only applies to successful i/o (io_error == 0)
2743 		 * because unlike i/o counts, errors are not additive.
2744 		 * When reading a ditto block, for example, failure of
2745 		 * one top-level vdev does not imply a root-level error.
2746 		 */
2747 		if (vd == rvd)
2748 			return;
2749 
2750 		ASSERT(vd == zio->io_vd);
2751 
2752 		if (flags & ZIO_FLAG_IO_BYPASS)
2753 			return;
2754 
2755 		mutex_enter(&vd->vdev_stat_lock);
2756 
2757 		if (flags & ZIO_FLAG_IO_REPAIR) {
2758 			if (flags & ZIO_FLAG_SCAN_THREAD) {
2759 				dsl_scan_phys_t *scn_phys =
2760 				    &spa->spa_dsl_pool->dp_scan->scn_phys;
2761 				uint64_t *processed = &scn_phys->scn_processed;
2762 
2763 				/* XXX cleanup? */
2764 				if (vd->vdev_ops->vdev_op_leaf)
2765 					atomic_add_64(processed, psize);
2766 				vs->vs_scan_processed += psize;
2767 			}
2768 
2769 			if (flags & ZIO_FLAG_SELF_HEAL)
2770 				vs->vs_self_healed += psize;
2771 		}
2772 
2773 		vs->vs_ops[type]++;
2774 		vs->vs_bytes[type] += psize;
2775 
2776 		mutex_exit(&vd->vdev_stat_lock);
2777 		return;
2778 	}
2779 
2780 	if (flags & ZIO_FLAG_SPECULATIVE)
2781 		return;
2782 
2783 	/*
2784 	 * If this is an I/O error that is going to be retried, then ignore the
2785 	 * error.  Otherwise, the user may interpret B_FAILFAST I/O errors as
2786 	 * hard errors, when in reality they can happen for any number of
2787 	 * innocuous reasons (bus resets, MPxIO link failure, etc).
2788 	 */
2789 	if (zio->io_error == EIO &&
2790 	    !(zio->io_flags & ZIO_FLAG_IO_RETRY))
2791 		return;
2792 
2793 	/*
2794 	 * Intent logs writes won't propagate their error to the root
2795 	 * I/O so don't mark these types of failures as pool-level
2796 	 * errors.
2797 	 */
2798 	if (zio->io_vd == NULL && (zio->io_flags & ZIO_FLAG_DONT_PROPAGATE))
2799 		return;
2800 
2801 	mutex_enter(&vd->vdev_stat_lock);
2802 	if (type == ZIO_TYPE_READ && !vdev_is_dead(vd)) {
2803 		if (zio->io_error == ECKSUM)
2804 			vs->vs_checksum_errors++;
2805 		else
2806 			vs->vs_read_errors++;
2807 	}
2808 	if (type == ZIO_TYPE_WRITE && !vdev_is_dead(vd))
2809 		vs->vs_write_errors++;
2810 	mutex_exit(&vd->vdev_stat_lock);
2811 
2812 	if (type == ZIO_TYPE_WRITE && txg != 0 &&
2813 	    (!(flags & ZIO_FLAG_IO_REPAIR) ||
2814 	    (flags & ZIO_FLAG_SCAN_THREAD) ||
2815 	    spa->spa_claiming)) {
2816 		/*
2817 		 * This is either a normal write (not a repair), or it's
2818 		 * a repair induced by the scrub thread, or it's a repair
2819 		 * made by zil_claim() during spa_load() in the first txg.
2820 		 * In the normal case, we commit the DTL change in the same
2821 		 * txg as the block was born.  In the scrub-induced repair
2822 		 * case, we know that scrubs run in first-pass syncing context,
2823 		 * so we commit the DTL change in spa_syncing_txg(spa).
2824 		 * In the zil_claim() case, we commit in spa_first_txg(spa).
2825 		 *
2826 		 * We currently do not make DTL entries for failed spontaneous
2827 		 * self-healing writes triggered by normal (non-scrubbing)
2828 		 * reads, because we have no transactional context in which to
2829 		 * do so -- and it's not clear that it'd be desirable anyway.
2830 		 */
2831 		if (vd->vdev_ops->vdev_op_leaf) {
2832 			uint64_t commit_txg = txg;
2833 			if (flags & ZIO_FLAG_SCAN_THREAD) {
2834 				ASSERT(flags & ZIO_FLAG_IO_REPAIR);
2835 				ASSERT(spa_sync_pass(spa) == 1);
2836 				vdev_dtl_dirty(vd, DTL_SCRUB, txg, 1);
2837 				commit_txg = spa_syncing_txg(spa);
2838 			} else if (spa->spa_claiming) {
2839 				ASSERT(flags & ZIO_FLAG_IO_REPAIR);
2840 				commit_txg = spa_first_txg(spa);
2841 			}
2842 			ASSERT(commit_txg >= spa_syncing_txg(spa));
2843 			if (vdev_dtl_contains(vd, DTL_MISSING, txg, 1))
2844 				return;
2845 			for (pvd = vd; pvd != rvd; pvd = pvd->vdev_parent)
2846 				vdev_dtl_dirty(pvd, DTL_PARTIAL, txg, 1);
2847 			vdev_dirty(vd->vdev_top, VDD_DTL, vd, commit_txg);
2848 		}
2849 		if (vd != rvd)
2850 			vdev_dtl_dirty(vd, DTL_MISSING, txg, 1);
2851 	}
2852 }
2853 
2854 /*
2855  * Update the in-core space usage stats for this vdev, its metaslab class,
2856  * and the root vdev.
2857  */
2858 void
2859 vdev_space_update(vdev_t *vd, int64_t alloc_delta, int64_t defer_delta,
2860     int64_t space_delta)
2861 {
2862 	int64_t dspace_delta = space_delta;
2863 	spa_t *spa = vd->vdev_spa;
2864 	vdev_t *rvd = spa->spa_root_vdev;
2865 	metaslab_group_t *mg = vd->vdev_mg;
2866 	metaslab_class_t *mc = mg ? mg->mg_class : NULL;
2867 
2868 	ASSERT(vd == vd->vdev_top);
2869 
2870 	/*
2871 	 * Apply the inverse of the psize-to-asize (ie. RAID-Z) space-expansion
2872 	 * factor.  We must calculate this here and not at the root vdev
2873 	 * because the root vdev's psize-to-asize is simply the max of its
2874 	 * childrens', thus not accurate enough for us.
2875 	 */
2876 	ASSERT((dspace_delta & (SPA_MINBLOCKSIZE-1)) == 0);
2877 	ASSERT(vd->vdev_deflate_ratio != 0 || vd->vdev_isl2cache);
2878 	dspace_delta = (dspace_delta >> SPA_MINBLOCKSHIFT) *
2879 	    vd->vdev_deflate_ratio;
2880 
2881 	mutex_enter(&vd->vdev_stat_lock);
2882 	vd->vdev_stat.vs_alloc += alloc_delta;
2883 	vd->vdev_stat.vs_space += space_delta;
2884 	vd->vdev_stat.vs_dspace += dspace_delta;
2885 	mutex_exit(&vd->vdev_stat_lock);
2886 
2887 	if (mc == spa_normal_class(spa)) {
2888 		mutex_enter(&rvd->vdev_stat_lock);
2889 		rvd->vdev_stat.vs_alloc += alloc_delta;
2890 		rvd->vdev_stat.vs_space += space_delta;
2891 		rvd->vdev_stat.vs_dspace += dspace_delta;
2892 		mutex_exit(&rvd->vdev_stat_lock);
2893 	}
2894 
2895 	if (mc != NULL) {
2896 		ASSERT(rvd == vd->vdev_parent);
2897 		ASSERT(vd->vdev_ms_count != 0);
2898 
2899 		metaslab_class_space_update(mc,
2900 		    alloc_delta, defer_delta, space_delta, dspace_delta);
2901 	}
2902 }
2903 
2904 /*
2905  * Mark a top-level vdev's config as dirty, placing it on the dirty list
2906  * so that it will be written out next time the vdev configuration is synced.
2907  * If the root vdev is specified (vdev_top == NULL), dirty all top-level vdevs.
2908  */
2909 void
2910 vdev_config_dirty(vdev_t *vd)
2911 {
2912 	spa_t *spa = vd->vdev_spa;
2913 	vdev_t *rvd = spa->spa_root_vdev;
2914 	int c;
2915 
2916 	ASSERT(spa_writeable(spa));
2917 
2918 	/*
2919 	 * If this is an aux vdev (as with l2cache and spare devices), then we
2920 	 * update the vdev config manually and set the sync flag.
2921 	 */
2922 	if (vd->vdev_aux != NULL) {
2923 		spa_aux_vdev_t *sav = vd->vdev_aux;
2924 		nvlist_t **aux;
2925 		uint_t naux;
2926 
2927 		for (c = 0; c < sav->sav_count; c++) {
2928 			if (sav->sav_vdevs[c] == vd)
2929 				break;
2930 		}
2931 
2932 		if (c == sav->sav_count) {
2933 			/*
2934 			 * We're being removed.  There's nothing more to do.
2935 			 */
2936 			ASSERT(sav->sav_sync == B_TRUE);
2937 			return;
2938 		}
2939 
2940 		sav->sav_sync = B_TRUE;
2941 
2942 		if (nvlist_lookup_nvlist_array(sav->sav_config,
2943 		    ZPOOL_CONFIG_L2CACHE, &aux, &naux) != 0) {
2944 			VERIFY(nvlist_lookup_nvlist_array(sav->sav_config,
2945 			    ZPOOL_CONFIG_SPARES, &aux, &naux) == 0);
2946 		}
2947 
2948 		ASSERT(c < naux);
2949 
2950 		/*
2951 		 * Setting the nvlist in the middle if the array is a little
2952 		 * sketchy, but it will work.
2953 		 */
2954 		nvlist_free(aux[c]);
2955 		aux[c] = vdev_config_generate(spa, vd, B_TRUE, 0);
2956 
2957 		return;
2958 	}
2959 
2960 	/*
2961 	 * The dirty list is protected by the SCL_CONFIG lock.  The caller
2962 	 * must either hold SCL_CONFIG as writer, or must be the sync thread
2963 	 * (which holds SCL_CONFIG as reader).  There's only one sync thread,
2964 	 * so this is sufficient to ensure mutual exclusion.
2965 	 */
2966 	ASSERT(spa_config_held(spa, SCL_CONFIG, RW_WRITER) ||
2967 	    (dsl_pool_sync_context(spa_get_dsl(spa)) &&
2968 	    spa_config_held(spa, SCL_CONFIG, RW_READER)));
2969 
2970 	if (vd == rvd) {
2971 		for (c = 0; c < rvd->vdev_children; c++)
2972 			vdev_config_dirty(rvd->vdev_child[c]);
2973 	} else {
2974 		ASSERT(vd == vd->vdev_top);
2975 
2976 		if (!list_link_active(&vd->vdev_config_dirty_node) &&
2977 		    !vd->vdev_ishole)
2978 			list_insert_head(&spa->spa_config_dirty_list, vd);
2979 	}
2980 }
2981 
2982 void
2983 vdev_config_clean(vdev_t *vd)
2984 {
2985 	spa_t *spa = vd->vdev_spa;
2986 
2987 	ASSERT(spa_config_held(spa, SCL_CONFIG, RW_WRITER) ||
2988 	    (dsl_pool_sync_context(spa_get_dsl(spa)) &&
2989 	    spa_config_held(spa, SCL_CONFIG, RW_READER)));
2990 
2991 	ASSERT(list_link_active(&vd->vdev_config_dirty_node));
2992 	list_remove(&spa->spa_config_dirty_list, vd);
2993 }
2994 
2995 /*
2996  * Mark a top-level vdev's state as dirty, so that the next pass of
2997  * spa_sync() can convert this into vdev_config_dirty().  We distinguish
2998  * the state changes from larger config changes because they require
2999  * much less locking, and are often needed for administrative actions.
3000  */
3001 void
3002 vdev_state_dirty(vdev_t *vd)
3003 {
3004 	spa_t *spa = vd->vdev_spa;
3005 
3006 	ASSERT(spa_writeable(spa));
3007 	ASSERT(vd == vd->vdev_top);
3008 
3009 	/*
3010 	 * The state list is protected by the SCL_STATE lock.  The caller
3011 	 * must either hold SCL_STATE as writer, or must be the sync thread
3012 	 * (which holds SCL_STATE as reader).  There's only one sync thread,
3013 	 * so this is sufficient to ensure mutual exclusion.
3014 	 */
3015 	ASSERT(spa_config_held(spa, SCL_STATE, RW_WRITER) ||
3016 	    (dsl_pool_sync_context(spa_get_dsl(spa)) &&
3017 	    spa_config_held(spa, SCL_STATE, RW_READER)));
3018 
3019 	if (!list_link_active(&vd->vdev_state_dirty_node) && !vd->vdev_ishole)
3020 		list_insert_head(&spa->spa_state_dirty_list, vd);
3021 }
3022 
3023 void
3024 vdev_state_clean(vdev_t *vd)
3025 {
3026 	spa_t *spa = vd->vdev_spa;
3027 
3028 	ASSERT(spa_config_held(spa, SCL_STATE, RW_WRITER) ||
3029 	    (dsl_pool_sync_context(spa_get_dsl(spa)) &&
3030 	    spa_config_held(spa, SCL_STATE, RW_READER)));
3031 
3032 	ASSERT(list_link_active(&vd->vdev_state_dirty_node));
3033 	list_remove(&spa->spa_state_dirty_list, vd);
3034 }
3035 
3036 /*
3037  * Propagate vdev state up from children to parent.
3038  */
3039 void
3040 vdev_propagate_state(vdev_t *vd)
3041 {
3042 	spa_t *spa = vd->vdev_spa;
3043 	vdev_t *rvd = spa->spa_root_vdev;
3044 	int degraded = 0, faulted = 0;
3045 	int corrupted = 0;
3046 	vdev_t *child;
3047 
3048 	if (vd->vdev_children > 0) {
3049 		for (int c = 0; c < vd->vdev_children; c++) {
3050 			child = vd->vdev_child[c];
3051 
3052 			/*
3053 			 * Don't factor holes into the decision.
3054 			 */
3055 			if (child->vdev_ishole)
3056 				continue;
3057 
3058 			if (!vdev_readable(child) ||
3059 			    (!vdev_writeable(child) && spa_writeable(spa))) {
3060 				/*
3061 				 * Root special: if there is a top-level log
3062 				 * device, treat the root vdev as if it were
3063 				 * degraded.
3064 				 */
3065 				if (child->vdev_islog && vd == rvd)
3066 					degraded++;
3067 				else
3068 					faulted++;
3069 			} else if (child->vdev_state <= VDEV_STATE_DEGRADED) {
3070 				degraded++;
3071 			}
3072 
3073 			if (child->vdev_stat.vs_aux == VDEV_AUX_CORRUPT_DATA)
3074 				corrupted++;
3075 		}
3076 
3077 		vd->vdev_ops->vdev_op_state_change(vd, faulted, degraded);
3078 
3079 		/*
3080 		 * Root special: if there is a top-level vdev that cannot be
3081 		 * opened due to corrupted metadata, then propagate the root
3082 		 * vdev's aux state as 'corrupt' rather than 'insufficient
3083 		 * replicas'.
3084 		 */
3085 		if (corrupted && vd == rvd &&
3086 		    rvd->vdev_state == VDEV_STATE_CANT_OPEN)
3087 			vdev_set_state(rvd, B_FALSE, VDEV_STATE_CANT_OPEN,
3088 			    VDEV_AUX_CORRUPT_DATA);
3089 	}
3090 
3091 	if (vd->vdev_parent)
3092 		vdev_propagate_state(vd->vdev_parent);
3093 }
3094 
3095 /*
3096  * Set a vdev's state.  If this is during an open, we don't update the parent
3097  * state, because we're in the process of opening children depth-first.
3098  * Otherwise, we propagate the change to the parent.
3099  *
3100  * If this routine places a device in a faulted state, an appropriate ereport is
3101  * generated.
3102  */
3103 void
3104 vdev_set_state(vdev_t *vd, boolean_t isopen, vdev_state_t state, vdev_aux_t aux)
3105 {
3106 	uint64_t save_state;
3107 	spa_t *spa = vd->vdev_spa;
3108 
3109 	if (state == vd->vdev_state) {
3110 		vd->vdev_stat.vs_aux = aux;
3111 		return;
3112 	}
3113 
3114 	save_state = vd->vdev_state;
3115 
3116 	vd->vdev_state = state;
3117 	vd->vdev_stat.vs_aux = aux;
3118 
3119 	/*
3120 	 * If we are setting the vdev state to anything but an open state, then
3121 	 * always close the underlying device unless the device has requested
3122 	 * a delayed close (i.e. we're about to remove or fault the device).
3123 	 * Otherwise, we keep accessible but invalid devices open forever.
3124 	 * We don't call vdev_close() itself, because that implies some extra
3125 	 * checks (offline, etc) that we don't want here.  This is limited to
3126 	 * leaf devices, because otherwise closing the device will affect other
3127 	 * children.
3128 	 */
3129 	if (!vd->vdev_delayed_close && vdev_is_dead(vd) &&
3130 	    vd->vdev_ops->vdev_op_leaf)
3131 		vd->vdev_ops->vdev_op_close(vd);
3132 
3133 	/*
3134 	 * If we have brought this vdev back into service, we need
3135 	 * to notify fmd so that it can gracefully repair any outstanding
3136 	 * cases due to a missing device.  We do this in all cases, even those
3137 	 * that probably don't correlate to a repaired fault.  This is sure to
3138 	 * catch all cases, and we let the zfs-retire agent sort it out.  If
3139 	 * this is a transient state it's OK, as the retire agent will
3140 	 * double-check the state of the vdev before repairing it.
3141 	 */
3142 	if (state == VDEV_STATE_HEALTHY && vd->vdev_ops->vdev_op_leaf &&
3143 	    vd->vdev_prevstate != state)
3144 		zfs_post_state_change(spa, vd);
3145 
3146 	if (vd->vdev_removed &&
3147 	    state == VDEV_STATE_CANT_OPEN &&
3148 	    (aux == VDEV_AUX_OPEN_FAILED || vd->vdev_checkremove)) {
3149 		/*
3150 		 * If the previous state is set to VDEV_STATE_REMOVED, then this
3151 		 * device was previously marked removed and someone attempted to
3152 		 * reopen it.  If this failed due to a nonexistent device, then
3153 		 * keep the device in the REMOVED state.  We also let this be if
3154 		 * it is one of our special test online cases, which is only
3155 		 * attempting to online the device and shouldn't generate an FMA
3156 		 * fault.
3157 		 */
3158 		vd->vdev_state = VDEV_STATE_REMOVED;
3159 		vd->vdev_stat.vs_aux = VDEV_AUX_NONE;
3160 	} else if (state == VDEV_STATE_REMOVED) {
3161 		vd->vdev_removed = B_TRUE;
3162 	} else if (state == VDEV_STATE_CANT_OPEN) {
3163 		/*
3164 		 * If we fail to open a vdev during an import or recovery, we
3165 		 * mark it as "not available", which signifies that it was
3166 		 * never there to begin with.  Failure to open such a device
3167 		 * is not considered an error.
3168 		 */
3169 		if ((spa_load_state(spa) == SPA_LOAD_IMPORT ||
3170 		    spa_load_state(spa) == SPA_LOAD_RECOVER) &&
3171 		    vd->vdev_ops->vdev_op_leaf)
3172 			vd->vdev_not_present = 1;
3173 
3174 		/*
3175 		 * Post the appropriate ereport.  If the 'prevstate' field is
3176 		 * set to something other than VDEV_STATE_UNKNOWN, it indicates
3177 		 * that this is part of a vdev_reopen().  In this case, we don't
3178 		 * want to post the ereport if the device was already in the
3179 		 * CANT_OPEN state beforehand.
3180 		 *
3181 		 * If the 'checkremove' flag is set, then this is an attempt to
3182 		 * online the device in response to an insertion event.  If we
3183 		 * hit this case, then we have detected an insertion event for a
3184 		 * faulted or offline device that wasn't in the removed state.
3185 		 * In this scenario, we don't post an ereport because we are
3186 		 * about to replace the device, or attempt an online with
3187 		 * vdev_forcefault, which will generate the fault for us.
3188 		 */
3189 		if ((vd->vdev_prevstate != state || vd->vdev_forcefault) &&
3190 		    !vd->vdev_not_present && !vd->vdev_checkremove &&
3191 		    vd != spa->spa_root_vdev) {
3192 			const char *class;
3193 
3194 			switch (aux) {
3195 			case VDEV_AUX_OPEN_FAILED:
3196 				class = FM_EREPORT_ZFS_DEVICE_OPEN_FAILED;
3197 				break;
3198 			case VDEV_AUX_CORRUPT_DATA:
3199 				class = FM_EREPORT_ZFS_DEVICE_CORRUPT_DATA;
3200 				break;
3201 			case VDEV_AUX_NO_REPLICAS:
3202 				class = FM_EREPORT_ZFS_DEVICE_NO_REPLICAS;
3203 				break;
3204 			case VDEV_AUX_BAD_GUID_SUM:
3205 				class = FM_EREPORT_ZFS_DEVICE_BAD_GUID_SUM;
3206 				break;
3207 			case VDEV_AUX_TOO_SMALL:
3208 				class = FM_EREPORT_ZFS_DEVICE_TOO_SMALL;
3209 				break;
3210 			case VDEV_AUX_BAD_LABEL:
3211 				class = FM_EREPORT_ZFS_DEVICE_BAD_LABEL;
3212 				break;
3213 			default:
3214 				class = FM_EREPORT_ZFS_DEVICE_UNKNOWN;
3215 			}
3216 
3217 			zfs_ereport_post(class, spa, vd, NULL, save_state, 0);
3218 		}
3219 
3220 		/* Erase any notion of persistent removed state */
3221 		vd->vdev_removed = B_FALSE;
3222 	} else {
3223 		vd->vdev_removed = B_FALSE;
3224 	}
3225 
3226 	if (!isopen && vd->vdev_parent)
3227 		vdev_propagate_state(vd->vdev_parent);
3228 }
3229 
3230 /*
3231  * Check the vdev configuration to ensure that it's capable of supporting
3232  * a root pool. Currently, we do not support RAID-Z or partial configuration.
3233  * In addition, only a single top-level vdev is allowed and none of the leaves
3234  * can be wholedisks.
3235  */
3236 boolean_t
3237 vdev_is_bootable(vdev_t *vd)
3238 {
3239 	if (!vd->vdev_ops->vdev_op_leaf) {
3240 		char *vdev_type = vd->vdev_ops->vdev_op_type;
3241 
3242 		if (strcmp(vdev_type, VDEV_TYPE_ROOT) == 0 &&
3243 		    vd->vdev_children > 1) {
3244 			return (B_FALSE);
3245 		} else if (strcmp(vdev_type, VDEV_TYPE_RAIDZ) == 0 ||
3246 		    strcmp(vdev_type, VDEV_TYPE_MISSING) == 0) {
3247 			return (B_FALSE);
3248 		}
3249 	}
3250 
3251 	for (int c = 0; c < vd->vdev_children; c++) {
3252 		if (!vdev_is_bootable(vd->vdev_child[c]))
3253 			return (B_FALSE);
3254 	}
3255 	return (B_TRUE);
3256 }
3257 
3258 /*
3259  * Load the state from the original vdev tree (ovd) which
3260  * we've retrieved from the MOS config object. If the original
3261  * vdev was offline or faulted then we transfer that state to the
3262  * device in the current vdev tree (nvd).
3263  */
3264 void
3265 vdev_load_log_state(vdev_t *nvd, vdev_t *ovd)
3266 {
3267 	spa_t *spa = nvd->vdev_spa;
3268 
3269 	ASSERT(nvd->vdev_top->vdev_islog);
3270 	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
3271 	ASSERT3U(nvd->vdev_guid, ==, ovd->vdev_guid);
3272 
3273 	for (int c = 0; c < nvd->vdev_children; c++)
3274 		vdev_load_log_state(nvd->vdev_child[c], ovd->vdev_child[c]);
3275 
3276 	if (nvd->vdev_ops->vdev_op_leaf) {
3277 		/*
3278 		 * Restore the persistent vdev state
3279 		 */
3280 		nvd->vdev_offline = ovd->vdev_offline;
3281 		nvd->vdev_faulted = ovd->vdev_faulted;
3282 		nvd->vdev_degraded = ovd->vdev_degraded;
3283 		nvd->vdev_removed = ovd->vdev_removed;
3284 	}
3285 }
3286 
3287 /*
3288  * Determine if a log device has valid content.  If the vdev was
3289  * removed or faulted in the MOS config then we know that
3290  * the content on the log device has already been written to the pool.
3291  */
3292 boolean_t
3293 vdev_log_state_valid(vdev_t *vd)
3294 {
3295 	if (vd->vdev_ops->vdev_op_leaf && !vd->vdev_faulted &&
3296 	    !vd->vdev_removed)
3297 		return (B_TRUE);
3298 
3299 	for (int c = 0; c < vd->vdev_children; c++)
3300 		if (vdev_log_state_valid(vd->vdev_child[c]))
3301 			return (B_TRUE);
3302 
3303 	return (B_FALSE);
3304 }
3305 
3306 /*
3307  * Expand a vdev if possible.
3308  */
3309 void
3310 vdev_expand(vdev_t *vd, uint64_t txg)
3311 {
3312 	ASSERT(vd->vdev_top == vd);
3313 	ASSERT(spa_config_held(vd->vdev_spa, SCL_ALL, RW_WRITER) == SCL_ALL);
3314 
3315 	if ((vd->vdev_asize >> vd->vdev_ms_shift) > vd->vdev_ms_count) {
3316 		VERIFY(vdev_metaslab_init(vd, txg) == 0);
3317 		vdev_config_dirty(vd);
3318 	}
3319 }
3320 
3321 /*
3322  * Split a vdev.
3323  */
3324 void
3325 vdev_split(vdev_t *vd)
3326 {
3327 	vdev_t *cvd, *pvd = vd->vdev_parent;
3328 
3329 	vdev_remove_child(pvd, vd);
3330 	vdev_compact_children(pvd);
3331 
3332 	cvd = pvd->vdev_child[0];
3333 	if (pvd->vdev_children == 1) {
3334 		vdev_remove_parent(cvd);
3335 		cvd->vdev_splitting = B_TRUE;
3336 	}
3337 	vdev_propagate_state(cvd);
3338 }
3339 
3340 void
3341 vdev_deadman(vdev_t *vd)
3342 {
3343 	for (int c = 0; c < vd->vdev_children; c++) {
3344 		vdev_t *cvd = vd->vdev_child[c];
3345 
3346 		vdev_deadman(cvd);
3347 	}
3348 
3349 	if (vd->vdev_ops->vdev_op_leaf) {
3350 		vdev_queue_t *vq = &vd->vdev_queue;
3351 
3352 		mutex_enter(&vq->vq_lock);
3353 		if (avl_numnodes(&vq->vq_active_tree) > 0) {
3354 			spa_t *spa = vd->vdev_spa;
3355 			zio_t *fio;
3356 			uint64_t delta;
3357 
3358 			/*
3359 			 * Look at the head of all the pending queues,
3360 			 * if any I/O has been outstanding for longer than
3361 			 * the spa_deadman_synctime we panic the system.
3362 			 */
3363 			fio = avl_first(&vq->vq_active_tree);
3364 			delta = gethrtime() - fio->io_timestamp;
3365 			if (delta > spa_deadman_synctime(spa)) {
3366 				zfs_dbgmsg("SLOW IO: zio timestamp %lluns, "
3367 				    "delta %lluns, last io %lluns",
3368 				    fio->io_timestamp, delta,
3369 				    vq->vq_io_complete_ts);
3370 				fm_panic("I/O to pool '%s' appears to be "
3371 				    "hung.", spa_name(spa));
3372 			}
3373 		}
3374 		mutex_exit(&vq->vq_lock);
3375 	}
3376 }
3377