xref: /illumos-gate/usr/src/uts/common/fs/zfs/vdev.c (revision 8c69cc8fbe729fa7b091e901c4b50508ccc6bb33)
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 2017 Nexenta Systems, Inc.
26  * Copyright (c) 2014 Integros [integros.com]
27  * Copyright 2016 Toomas Soome <tsoome@me.com>
28  * Copyright 2017 Joyent, Inc.
29  */
30 
31 #include <sys/zfs_context.h>
32 #include <sys/fm/fs/zfs.h>
33 #include <sys/spa.h>
34 #include <sys/spa_impl.h>
35 #include <sys/dmu.h>
36 #include <sys/dmu_tx.h>
37 #include <sys/vdev_impl.h>
38 #include <sys/uberblock_impl.h>
39 #include <sys/metaslab.h>
40 #include <sys/metaslab_impl.h>
41 #include <sys/space_map.h>
42 #include <sys/space_reftree.h>
43 #include <sys/zio.h>
44 #include <sys/zap.h>
45 #include <sys/fs/zfs.h>
46 #include <sys/arc.h>
47 #include <sys/zil.h>
48 #include <sys/dsl_scan.h>
49 #include <sys/abd.h>
50 
51 /*
52  * Virtual device management.
53  */
54 
55 static vdev_ops_t *vdev_ops_table[] = {
56 	&vdev_root_ops,
57 	&vdev_raidz_ops,
58 	&vdev_mirror_ops,
59 	&vdev_replacing_ops,
60 	&vdev_spare_ops,
61 	&vdev_disk_ops,
62 	&vdev_file_ops,
63 	&vdev_missing_ops,
64 	&vdev_hole_ops,
65 	NULL
66 };
67 
68 /* maximum scrub/resilver I/O queue per leaf vdev */
69 int zfs_scrub_limit = 10;
70 
71 /*
72  * When a vdev is added, it will be divided into approximately (but no
73  * more than) this number of metaslabs.
74  */
75 int metaslabs_per_vdev = 200;
76 
77 /*
78  * Given a vdev type, return the appropriate ops vector.
79  */
80 static vdev_ops_t *
81 vdev_getops(const char *type)
82 {
83 	vdev_ops_t *ops, **opspp;
84 
85 	for (opspp = vdev_ops_table; (ops = *opspp) != NULL; opspp++)
86 		if (strcmp(ops->vdev_op_type, type) == 0)
87 			break;
88 
89 	return (ops);
90 }
91 
92 /*
93  * Default asize function: return the MAX of psize with the asize of
94  * all children.  This is what's used by anything other than RAID-Z.
95  */
96 uint64_t
97 vdev_default_asize(vdev_t *vd, uint64_t psize)
98 {
99 	uint64_t asize = P2ROUNDUP(psize, 1ULL << vd->vdev_top->vdev_ashift);
100 	uint64_t csize;
101 
102 	for (int c = 0; c < vd->vdev_children; c++) {
103 		csize = vdev_psize_to_asize(vd->vdev_child[c], psize);
104 		asize = MAX(asize, csize);
105 	}
106 
107 	return (asize);
108 }
109 
110 /*
111  * Get the minimum allocatable size. We define the allocatable size as
112  * the vdev's asize rounded to the nearest metaslab. This allows us to
113  * replace or attach devices which don't have the same physical size but
114  * can still satisfy the same number of allocations.
115  */
116 uint64_t
117 vdev_get_min_asize(vdev_t *vd)
118 {
119 	vdev_t *pvd = vd->vdev_parent;
120 
121 	/*
122 	 * If our parent is NULL (inactive spare or cache) or is the root,
123 	 * just return our own asize.
124 	 */
125 	if (pvd == NULL)
126 		return (vd->vdev_asize);
127 
128 	/*
129 	 * The top-level vdev just returns the allocatable size rounded
130 	 * to the nearest metaslab.
131 	 */
132 	if (vd == vd->vdev_top)
133 		return (P2ALIGN(vd->vdev_asize, 1ULL << vd->vdev_ms_shift));
134 
135 	/*
136 	 * The allocatable space for a raidz vdev is N * sizeof(smallest child),
137 	 * so each child must provide at least 1/Nth of its asize.
138 	 */
139 	if (pvd->vdev_ops == &vdev_raidz_ops)
140 		return ((pvd->vdev_min_asize + pvd->vdev_children - 1) /
141 		    pvd->vdev_children);
142 
143 	return (pvd->vdev_min_asize);
144 }
145 
146 void
147 vdev_set_min_asize(vdev_t *vd)
148 {
149 	vd->vdev_min_asize = vdev_get_min_asize(vd);
150 
151 	for (int c = 0; c < vd->vdev_children; c++)
152 		vdev_set_min_asize(vd->vdev_child[c]);
153 }
154 
155 vdev_t *
156 vdev_lookup_top(spa_t *spa, uint64_t vdev)
157 {
158 	vdev_t *rvd = spa->spa_root_vdev;
159 
160 	ASSERT(spa_config_held(spa, SCL_ALL, RW_READER) != 0);
161 
162 	if (vdev < rvd->vdev_children) {
163 		ASSERT(rvd->vdev_child[vdev] != NULL);
164 		return (rvd->vdev_child[vdev]);
165 	}
166 
167 	return (NULL);
168 }
169 
170 vdev_t *
171 vdev_lookup_by_guid(vdev_t *vd, uint64_t guid)
172 {
173 	vdev_t *mvd;
174 
175 	if (vd->vdev_guid == guid)
176 		return (vd);
177 
178 	for (int c = 0; c < vd->vdev_children; c++)
179 		if ((mvd = vdev_lookup_by_guid(vd->vdev_child[c], guid)) !=
180 		    NULL)
181 			return (mvd);
182 
183 	return (NULL);
184 }
185 
186 static int
187 vdev_count_leaves_impl(vdev_t *vd)
188 {
189 	int n = 0;
190 
191 	if (vd->vdev_ops->vdev_op_leaf)
192 		return (1);
193 
194 	for (int c = 0; c < vd->vdev_children; c++)
195 		n += vdev_count_leaves_impl(vd->vdev_child[c]);
196 
197 	return (n);
198 }
199 
200 int
201 vdev_count_leaves(spa_t *spa)
202 {
203 	return (vdev_count_leaves_impl(spa->spa_root_vdev));
204 }
205 
206 void
207 vdev_add_child(vdev_t *pvd, vdev_t *cvd)
208 {
209 	size_t oldsize, newsize;
210 	uint64_t id = cvd->vdev_id;
211 	vdev_t **newchild;
212 	spa_t *spa = cvd->vdev_spa;
213 
214 	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
215 	ASSERT(cvd->vdev_parent == NULL);
216 
217 	cvd->vdev_parent = pvd;
218 
219 	if (pvd == NULL)
220 		return;
221 
222 	ASSERT(id >= pvd->vdev_children || pvd->vdev_child[id] == NULL);
223 
224 	oldsize = pvd->vdev_children * sizeof (vdev_t *);
225 	pvd->vdev_children = MAX(pvd->vdev_children, id + 1);
226 	newsize = pvd->vdev_children * sizeof (vdev_t *);
227 
228 	newchild = kmem_zalloc(newsize, KM_SLEEP);
229 	if (pvd->vdev_child != NULL) {
230 		bcopy(pvd->vdev_child, newchild, oldsize);
231 		kmem_free(pvd->vdev_child, oldsize);
232 	}
233 
234 	pvd->vdev_child = newchild;
235 	pvd->vdev_child[id] = cvd;
236 
237 	cvd->vdev_top = (pvd->vdev_top ? pvd->vdev_top: cvd);
238 	ASSERT(cvd->vdev_top->vdev_parent->vdev_parent == NULL);
239 
240 	/*
241 	 * Walk up all ancestors to update guid sum.
242 	 */
243 	for (; pvd != NULL; pvd = pvd->vdev_parent)
244 		pvd->vdev_guid_sum += cvd->vdev_guid_sum;
245 }
246 
247 void
248 vdev_remove_child(vdev_t *pvd, vdev_t *cvd)
249 {
250 	int c;
251 	uint_t id = cvd->vdev_id;
252 
253 	ASSERT(cvd->vdev_parent == pvd);
254 
255 	if (pvd == NULL)
256 		return;
257 
258 	ASSERT(id < pvd->vdev_children);
259 	ASSERT(pvd->vdev_child[id] == cvd);
260 
261 	pvd->vdev_child[id] = NULL;
262 	cvd->vdev_parent = NULL;
263 
264 	for (c = 0; c < pvd->vdev_children; c++)
265 		if (pvd->vdev_child[c])
266 			break;
267 
268 	if (c == pvd->vdev_children) {
269 		kmem_free(pvd->vdev_child, c * sizeof (vdev_t *));
270 		pvd->vdev_child = NULL;
271 		pvd->vdev_children = 0;
272 	}
273 
274 	/*
275 	 * Walk up all ancestors to update guid sum.
276 	 */
277 	for (; pvd != NULL; pvd = pvd->vdev_parent)
278 		pvd->vdev_guid_sum -= cvd->vdev_guid_sum;
279 }
280 
281 /*
282  * Remove any holes in the child array.
283  */
284 void
285 vdev_compact_children(vdev_t *pvd)
286 {
287 	vdev_t **newchild, *cvd;
288 	int oldc = pvd->vdev_children;
289 	int newc;
290 
291 	ASSERT(spa_config_held(pvd->vdev_spa, SCL_ALL, RW_WRITER) == SCL_ALL);
292 
293 	for (int c = newc = 0; c < oldc; c++)
294 		if (pvd->vdev_child[c])
295 			newc++;
296 
297 	newchild = kmem_alloc(newc * sizeof (vdev_t *), KM_SLEEP);
298 
299 	for (int c = newc = 0; c < oldc; c++) {
300 		if ((cvd = pvd->vdev_child[c]) != NULL) {
301 			newchild[newc] = cvd;
302 			cvd->vdev_id = newc++;
303 		}
304 	}
305 
306 	kmem_free(pvd->vdev_child, oldc * sizeof (vdev_t *));
307 	pvd->vdev_child = newchild;
308 	pvd->vdev_children = newc;
309 }
310 
311 /*
312  * Allocate and minimally initialize a vdev_t.
313  */
314 vdev_t *
315 vdev_alloc_common(spa_t *spa, uint_t id, uint64_t guid, vdev_ops_t *ops)
316 {
317 	vdev_t *vd;
318 
319 	vd = kmem_zalloc(sizeof (vdev_t), KM_SLEEP);
320 
321 	if (spa->spa_root_vdev == NULL) {
322 		ASSERT(ops == &vdev_root_ops);
323 		spa->spa_root_vdev = vd;
324 		spa->spa_load_guid = spa_generate_guid(NULL);
325 	}
326 
327 	if (guid == 0 && ops != &vdev_hole_ops) {
328 		if (spa->spa_root_vdev == vd) {
329 			/*
330 			 * The root vdev's guid will also be the pool guid,
331 			 * which must be unique among all pools.
332 			 */
333 			guid = spa_generate_guid(NULL);
334 		} else {
335 			/*
336 			 * Any other vdev's guid must be unique within the pool.
337 			 */
338 			guid = spa_generate_guid(spa);
339 		}
340 		ASSERT(!spa_guid_exists(spa_guid(spa), guid));
341 	}
342 
343 	vd->vdev_spa = spa;
344 	vd->vdev_id = id;
345 	vd->vdev_guid = guid;
346 	vd->vdev_guid_sum = guid;
347 	vd->vdev_ops = ops;
348 	vd->vdev_state = VDEV_STATE_CLOSED;
349 	vd->vdev_ishole = (ops == &vdev_hole_ops);
350 
351 	mutex_init(&vd->vdev_dtl_lock, NULL, MUTEX_DEFAULT, NULL);
352 	mutex_init(&vd->vdev_stat_lock, NULL, MUTEX_DEFAULT, NULL);
353 	mutex_init(&vd->vdev_probe_lock, NULL, MUTEX_DEFAULT, NULL);
354 	mutex_init(&vd->vdev_queue_lock, NULL, MUTEX_DEFAULT, NULL);
355 	for (int t = 0; t < DTL_TYPES; t++) {
356 		vd->vdev_dtl[t] = range_tree_create(NULL, NULL,
357 		    &vd->vdev_dtl_lock);
358 	}
359 	txg_list_create(&vd->vdev_ms_list, spa,
360 	    offsetof(struct metaslab, ms_txg_node));
361 	txg_list_create(&vd->vdev_dtl_list, spa,
362 	    offsetof(struct vdev, vdev_dtl_node));
363 	vd->vdev_stat.vs_timestamp = gethrtime();
364 	vdev_queue_init(vd);
365 	vdev_cache_init(vd);
366 
367 	return (vd);
368 }
369 
370 /*
371  * Allocate a new vdev.  The 'alloctype' is used to control whether we are
372  * creating a new vdev or loading an existing one - the behavior is slightly
373  * different for each case.
374  */
375 int
376 vdev_alloc(spa_t *spa, vdev_t **vdp, nvlist_t *nv, vdev_t *parent, uint_t id,
377     int alloctype)
378 {
379 	vdev_ops_t *ops;
380 	char *type;
381 	uint64_t guid = 0, islog, nparity;
382 	vdev_t *vd;
383 
384 	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
385 
386 	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_TYPE, &type) != 0)
387 		return (SET_ERROR(EINVAL));
388 
389 	if ((ops = vdev_getops(type)) == NULL)
390 		return (SET_ERROR(EINVAL));
391 
392 	/*
393 	 * If this is a load, get the vdev guid from the nvlist.
394 	 * Otherwise, vdev_alloc_common() will generate one for us.
395 	 */
396 	if (alloctype == VDEV_ALLOC_LOAD) {
397 		uint64_t label_id;
398 
399 		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_ID, &label_id) ||
400 		    label_id != id)
401 			return (SET_ERROR(EINVAL));
402 
403 		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_GUID, &guid) != 0)
404 			return (SET_ERROR(EINVAL));
405 	} else if (alloctype == VDEV_ALLOC_SPARE) {
406 		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_GUID, &guid) != 0)
407 			return (SET_ERROR(EINVAL));
408 	} else if (alloctype == VDEV_ALLOC_L2CACHE) {
409 		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_GUID, &guid) != 0)
410 			return (SET_ERROR(EINVAL));
411 	} else if (alloctype == VDEV_ALLOC_ROOTPOOL) {
412 		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_GUID, &guid) != 0)
413 			return (SET_ERROR(EINVAL));
414 	}
415 
416 	/*
417 	 * The first allocated vdev must be of type 'root'.
418 	 */
419 	if (ops != &vdev_root_ops && spa->spa_root_vdev == NULL)
420 		return (SET_ERROR(EINVAL));
421 
422 	/*
423 	 * Determine whether we're a log vdev.
424 	 */
425 	islog = 0;
426 	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_IS_LOG, &islog);
427 	if (islog && spa_version(spa) < SPA_VERSION_SLOGS)
428 		return (SET_ERROR(ENOTSUP));
429 
430 	if (ops == &vdev_hole_ops && spa_version(spa) < SPA_VERSION_HOLES)
431 		return (SET_ERROR(ENOTSUP));
432 
433 	/*
434 	 * Set the nparity property for RAID-Z vdevs.
435 	 */
436 	nparity = -1ULL;
437 	if (ops == &vdev_raidz_ops) {
438 		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_NPARITY,
439 		    &nparity) == 0) {
440 			if (nparity == 0 || nparity > VDEV_RAIDZ_MAXPARITY)
441 				return (SET_ERROR(EINVAL));
442 			/*
443 			 * Previous versions could only support 1 or 2 parity
444 			 * device.
445 			 */
446 			if (nparity > 1 &&
447 			    spa_version(spa) < SPA_VERSION_RAIDZ2)
448 				return (SET_ERROR(ENOTSUP));
449 			if (nparity > 2 &&
450 			    spa_version(spa) < SPA_VERSION_RAIDZ3)
451 				return (SET_ERROR(ENOTSUP));
452 		} else {
453 			/*
454 			 * We require the parity to be specified for SPAs that
455 			 * support multiple parity levels.
456 			 */
457 			if (spa_version(spa) >= SPA_VERSION_RAIDZ2)
458 				return (SET_ERROR(EINVAL));
459 			/*
460 			 * Otherwise, we default to 1 parity device for RAID-Z.
461 			 */
462 			nparity = 1;
463 		}
464 	} else {
465 		nparity = 0;
466 	}
467 	ASSERT(nparity != -1ULL);
468 
469 	vd = vdev_alloc_common(spa, id, guid, ops);
470 
471 	vd->vdev_islog = islog;
472 	vd->vdev_nparity = nparity;
473 
474 	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_PATH, &vd->vdev_path) == 0)
475 		vd->vdev_path = spa_strdup(vd->vdev_path);
476 	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_DEVID, &vd->vdev_devid) == 0)
477 		vd->vdev_devid = spa_strdup(vd->vdev_devid);
478 	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_PHYS_PATH,
479 	    &vd->vdev_physpath) == 0)
480 		vd->vdev_physpath = spa_strdup(vd->vdev_physpath);
481 	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_FRU, &vd->vdev_fru) == 0)
482 		vd->vdev_fru = spa_strdup(vd->vdev_fru);
483 
484 	/*
485 	 * Set the whole_disk property.  If it's not specified, leave the value
486 	 * as -1.
487 	 */
488 	if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK,
489 	    &vd->vdev_wholedisk) != 0)
490 		vd->vdev_wholedisk = -1ULL;
491 
492 	/*
493 	 * Look for the 'not present' flag.  This will only be set if the device
494 	 * was not present at the time of import.
495 	 */
496 	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_NOT_PRESENT,
497 	    &vd->vdev_not_present);
498 
499 	/*
500 	 * Get the alignment requirement.
501 	 */
502 	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_ASHIFT, &vd->vdev_ashift);
503 
504 	/*
505 	 * Retrieve the vdev creation time.
506 	 */
507 	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_CREATE_TXG,
508 	    &vd->vdev_crtxg);
509 
510 	/*
511 	 * If we're a top-level vdev, try to load the allocation parameters.
512 	 */
513 	if (parent && !parent->vdev_parent &&
514 	    (alloctype == VDEV_ALLOC_LOAD || alloctype == VDEV_ALLOC_SPLIT)) {
515 		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_METASLAB_ARRAY,
516 		    &vd->vdev_ms_array);
517 		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_METASLAB_SHIFT,
518 		    &vd->vdev_ms_shift);
519 		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_ASIZE,
520 		    &vd->vdev_asize);
521 		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_REMOVING,
522 		    &vd->vdev_removing);
523 		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_VDEV_TOP_ZAP,
524 		    &vd->vdev_top_zap);
525 	} else {
526 		ASSERT0(vd->vdev_top_zap);
527 	}
528 
529 	if (parent && !parent->vdev_parent && alloctype != VDEV_ALLOC_ATTACH) {
530 		ASSERT(alloctype == VDEV_ALLOC_LOAD ||
531 		    alloctype == VDEV_ALLOC_ADD ||
532 		    alloctype == VDEV_ALLOC_SPLIT ||
533 		    alloctype == VDEV_ALLOC_ROOTPOOL);
534 		vd->vdev_mg = metaslab_group_create(islog ?
535 		    spa_log_class(spa) : spa_normal_class(spa), vd);
536 	}
537 
538 	if (vd->vdev_ops->vdev_op_leaf &&
539 	    (alloctype == VDEV_ALLOC_LOAD || alloctype == VDEV_ALLOC_SPLIT)) {
540 		(void) nvlist_lookup_uint64(nv,
541 		    ZPOOL_CONFIG_VDEV_LEAF_ZAP, &vd->vdev_leaf_zap);
542 	} else {
543 		ASSERT0(vd->vdev_leaf_zap);
544 	}
545 
546 	/*
547 	 * If we're a leaf vdev, try to load the DTL object and other state.
548 	 */
549 
550 	if (vd->vdev_ops->vdev_op_leaf &&
551 	    (alloctype == VDEV_ALLOC_LOAD || alloctype == VDEV_ALLOC_L2CACHE ||
552 	    alloctype == VDEV_ALLOC_ROOTPOOL)) {
553 		if (alloctype == VDEV_ALLOC_LOAD) {
554 			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_DTL,
555 			    &vd->vdev_dtl_object);
556 			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_UNSPARE,
557 			    &vd->vdev_unspare);
558 		}
559 
560 		if (alloctype == VDEV_ALLOC_ROOTPOOL) {
561 			uint64_t spare = 0;
562 
563 			if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_IS_SPARE,
564 			    &spare) == 0 && spare)
565 				spa_spare_add(vd);
566 		}
567 
568 		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_OFFLINE,
569 		    &vd->vdev_offline);
570 
571 		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_RESILVER_TXG,
572 		    &vd->vdev_resilver_txg);
573 
574 		/*
575 		 * When importing a pool, we want to ignore the persistent fault
576 		 * state, as the diagnosis made on another system may not be
577 		 * valid in the current context.  Local vdevs will
578 		 * remain in the faulted state.
579 		 */
580 		if (spa_load_state(spa) == SPA_LOAD_OPEN) {
581 			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_FAULTED,
582 			    &vd->vdev_faulted);
583 			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_DEGRADED,
584 			    &vd->vdev_degraded);
585 			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_REMOVED,
586 			    &vd->vdev_removed);
587 
588 			if (vd->vdev_faulted || vd->vdev_degraded) {
589 				char *aux;
590 
591 				vd->vdev_label_aux =
592 				    VDEV_AUX_ERR_EXCEEDED;
593 				if (nvlist_lookup_string(nv,
594 				    ZPOOL_CONFIG_AUX_STATE, &aux) == 0 &&
595 				    strcmp(aux, "external") == 0)
596 					vd->vdev_label_aux = VDEV_AUX_EXTERNAL;
597 			}
598 		}
599 	}
600 
601 	/*
602 	 * Add ourselves to the parent's list of children.
603 	 */
604 	vdev_add_child(parent, vd);
605 
606 	*vdp = vd;
607 
608 	return (0);
609 }
610 
611 void
612 vdev_free(vdev_t *vd)
613 {
614 	spa_t *spa = vd->vdev_spa;
615 
616 	/*
617 	 * vdev_free() implies closing the vdev first.  This is simpler than
618 	 * trying to ensure complicated semantics for all callers.
619 	 */
620 	vdev_close(vd);
621 
622 	ASSERT(!list_link_active(&vd->vdev_config_dirty_node));
623 	ASSERT(!list_link_active(&vd->vdev_state_dirty_node));
624 
625 	/*
626 	 * Free all children.
627 	 */
628 	for (int c = 0; c < vd->vdev_children; c++)
629 		vdev_free(vd->vdev_child[c]);
630 
631 	ASSERT(vd->vdev_child == NULL);
632 	ASSERT(vd->vdev_guid_sum == vd->vdev_guid);
633 
634 	/*
635 	 * Discard allocation state.
636 	 */
637 	if (vd->vdev_mg != NULL) {
638 		vdev_metaslab_fini(vd);
639 		metaslab_group_destroy(vd->vdev_mg);
640 	}
641 
642 	ASSERT0(vd->vdev_stat.vs_space);
643 	ASSERT0(vd->vdev_stat.vs_dspace);
644 	ASSERT0(vd->vdev_stat.vs_alloc);
645 
646 	/*
647 	 * Remove this vdev from its parent's child list.
648 	 */
649 	vdev_remove_child(vd->vdev_parent, vd);
650 
651 	ASSERT(vd->vdev_parent == NULL);
652 
653 	/*
654 	 * Clean up vdev structure.
655 	 */
656 	vdev_queue_fini(vd);
657 	vdev_cache_fini(vd);
658 
659 	if (vd->vdev_path)
660 		spa_strfree(vd->vdev_path);
661 	if (vd->vdev_devid)
662 		spa_strfree(vd->vdev_devid);
663 	if (vd->vdev_physpath)
664 		spa_strfree(vd->vdev_physpath);
665 	if (vd->vdev_fru)
666 		spa_strfree(vd->vdev_fru);
667 
668 	if (vd->vdev_isspare)
669 		spa_spare_remove(vd);
670 	if (vd->vdev_isl2cache)
671 		spa_l2cache_remove(vd);
672 
673 	txg_list_destroy(&vd->vdev_ms_list);
674 	txg_list_destroy(&vd->vdev_dtl_list);
675 
676 	mutex_enter(&vd->vdev_dtl_lock);
677 	space_map_close(vd->vdev_dtl_sm);
678 	for (int t = 0; t < DTL_TYPES; t++) {
679 		range_tree_vacate(vd->vdev_dtl[t], NULL, NULL);
680 		range_tree_destroy(vd->vdev_dtl[t]);
681 	}
682 	mutex_exit(&vd->vdev_dtl_lock);
683 
684 	mutex_destroy(&vd->vdev_queue_lock);
685 	mutex_destroy(&vd->vdev_dtl_lock);
686 	mutex_destroy(&vd->vdev_stat_lock);
687 	mutex_destroy(&vd->vdev_probe_lock);
688 
689 	if (vd == spa->spa_root_vdev)
690 		spa->spa_root_vdev = NULL;
691 
692 	kmem_free(vd, sizeof (vdev_t));
693 }
694 
695 /*
696  * Transfer top-level vdev state from svd to tvd.
697  */
698 static void
699 vdev_top_transfer(vdev_t *svd, vdev_t *tvd)
700 {
701 	spa_t *spa = svd->vdev_spa;
702 	metaslab_t *msp;
703 	vdev_t *vd;
704 	int t;
705 
706 	ASSERT(tvd == tvd->vdev_top);
707 
708 	tvd->vdev_ms_array = svd->vdev_ms_array;
709 	tvd->vdev_ms_shift = svd->vdev_ms_shift;
710 	tvd->vdev_ms_count = svd->vdev_ms_count;
711 	tvd->vdev_top_zap = svd->vdev_top_zap;
712 
713 	svd->vdev_ms_array = 0;
714 	svd->vdev_ms_shift = 0;
715 	svd->vdev_ms_count = 0;
716 	svd->vdev_top_zap = 0;
717 
718 	if (tvd->vdev_mg)
719 		ASSERT3P(tvd->vdev_mg, ==, svd->vdev_mg);
720 	tvd->vdev_mg = svd->vdev_mg;
721 	tvd->vdev_ms = svd->vdev_ms;
722 
723 	svd->vdev_mg = NULL;
724 	svd->vdev_ms = NULL;
725 
726 	if (tvd->vdev_mg != NULL)
727 		tvd->vdev_mg->mg_vd = tvd;
728 
729 	tvd->vdev_stat.vs_alloc = svd->vdev_stat.vs_alloc;
730 	tvd->vdev_stat.vs_space = svd->vdev_stat.vs_space;
731 	tvd->vdev_stat.vs_dspace = svd->vdev_stat.vs_dspace;
732 
733 	svd->vdev_stat.vs_alloc = 0;
734 	svd->vdev_stat.vs_space = 0;
735 	svd->vdev_stat.vs_dspace = 0;
736 
737 	for (t = 0; t < TXG_SIZE; t++) {
738 		while ((msp = txg_list_remove(&svd->vdev_ms_list, t)) != NULL)
739 			(void) txg_list_add(&tvd->vdev_ms_list, msp, t);
740 		while ((vd = txg_list_remove(&svd->vdev_dtl_list, t)) != NULL)
741 			(void) txg_list_add(&tvd->vdev_dtl_list, vd, t);
742 		if (txg_list_remove_this(&spa->spa_vdev_txg_list, svd, t))
743 			(void) txg_list_add(&spa->spa_vdev_txg_list, tvd, t);
744 	}
745 
746 	if (list_link_active(&svd->vdev_config_dirty_node)) {
747 		vdev_config_clean(svd);
748 		vdev_config_dirty(tvd);
749 	}
750 
751 	if (list_link_active(&svd->vdev_state_dirty_node)) {
752 		vdev_state_clean(svd);
753 		vdev_state_dirty(tvd);
754 	}
755 
756 	tvd->vdev_deflate_ratio = svd->vdev_deflate_ratio;
757 	svd->vdev_deflate_ratio = 0;
758 
759 	tvd->vdev_islog = svd->vdev_islog;
760 	svd->vdev_islog = 0;
761 }
762 
763 static void
764 vdev_top_update(vdev_t *tvd, vdev_t *vd)
765 {
766 	if (vd == NULL)
767 		return;
768 
769 	vd->vdev_top = tvd;
770 
771 	for (int c = 0; c < vd->vdev_children; c++)
772 		vdev_top_update(tvd, vd->vdev_child[c]);
773 }
774 
775 /*
776  * Add a mirror/replacing vdev above an existing vdev.
777  */
778 vdev_t *
779 vdev_add_parent(vdev_t *cvd, vdev_ops_t *ops)
780 {
781 	spa_t *spa = cvd->vdev_spa;
782 	vdev_t *pvd = cvd->vdev_parent;
783 	vdev_t *mvd;
784 
785 	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
786 
787 	mvd = vdev_alloc_common(spa, cvd->vdev_id, 0, ops);
788 
789 	mvd->vdev_asize = cvd->vdev_asize;
790 	mvd->vdev_min_asize = cvd->vdev_min_asize;
791 	mvd->vdev_max_asize = cvd->vdev_max_asize;
792 	mvd->vdev_ashift = cvd->vdev_ashift;
793 	mvd->vdev_state = cvd->vdev_state;
794 	mvd->vdev_crtxg = cvd->vdev_crtxg;
795 
796 	vdev_remove_child(pvd, cvd);
797 	vdev_add_child(pvd, mvd);
798 	cvd->vdev_id = mvd->vdev_children;
799 	vdev_add_child(mvd, cvd);
800 	vdev_top_update(cvd->vdev_top, cvd->vdev_top);
801 
802 	if (mvd == mvd->vdev_top)
803 		vdev_top_transfer(cvd, mvd);
804 
805 	return (mvd);
806 }
807 
808 /*
809  * Remove a 1-way mirror/replacing vdev from the tree.
810  */
811 void
812 vdev_remove_parent(vdev_t *cvd)
813 {
814 	vdev_t *mvd = cvd->vdev_parent;
815 	vdev_t *pvd = mvd->vdev_parent;
816 
817 	ASSERT(spa_config_held(cvd->vdev_spa, SCL_ALL, RW_WRITER) == SCL_ALL);
818 
819 	ASSERT(mvd->vdev_children == 1);
820 	ASSERT(mvd->vdev_ops == &vdev_mirror_ops ||
821 	    mvd->vdev_ops == &vdev_replacing_ops ||
822 	    mvd->vdev_ops == &vdev_spare_ops);
823 	cvd->vdev_ashift = mvd->vdev_ashift;
824 
825 	vdev_remove_child(mvd, cvd);
826 	vdev_remove_child(pvd, mvd);
827 
828 	/*
829 	 * If cvd will replace mvd as a top-level vdev, preserve mvd's guid.
830 	 * Otherwise, we could have detached an offline device, and when we
831 	 * go to import the pool we'll think we have two top-level vdevs,
832 	 * instead of a different version of the same top-level vdev.
833 	 */
834 	if (mvd->vdev_top == mvd) {
835 		uint64_t guid_delta = mvd->vdev_guid - cvd->vdev_guid;
836 		cvd->vdev_orig_guid = cvd->vdev_guid;
837 		cvd->vdev_guid += guid_delta;
838 		cvd->vdev_guid_sum += guid_delta;
839 	}
840 	cvd->vdev_id = mvd->vdev_id;
841 	vdev_add_child(pvd, cvd);
842 	vdev_top_update(cvd->vdev_top, cvd->vdev_top);
843 
844 	if (cvd == cvd->vdev_top)
845 		vdev_top_transfer(mvd, cvd);
846 
847 	ASSERT(mvd->vdev_children == 0);
848 	vdev_free(mvd);
849 }
850 
851 int
852 vdev_metaslab_init(vdev_t *vd, uint64_t txg)
853 {
854 	spa_t *spa = vd->vdev_spa;
855 	objset_t *mos = spa->spa_meta_objset;
856 	uint64_t m;
857 	uint64_t oldc = vd->vdev_ms_count;
858 	uint64_t newc = vd->vdev_asize >> vd->vdev_ms_shift;
859 	metaslab_t **mspp;
860 	int error;
861 
862 	ASSERT(txg == 0 || spa_config_held(spa, SCL_ALLOC, RW_WRITER));
863 
864 	/*
865 	 * This vdev is not being allocated from yet or is a hole.
866 	 */
867 	if (vd->vdev_ms_shift == 0)
868 		return (0);
869 
870 	ASSERT(!vd->vdev_ishole);
871 
872 	/*
873 	 * Compute the raidz-deflation ratio.  Note, we hard-code
874 	 * in 128k (1 << 17) because it is the "typical" blocksize.
875 	 * Even though SPA_MAXBLOCKSIZE changed, this algorithm can not change,
876 	 * otherwise it would inconsistently account for existing bp's.
877 	 */
878 	vd->vdev_deflate_ratio = (1 << 17) /
879 	    (vdev_psize_to_asize(vd, 1 << 17) >> SPA_MINBLOCKSHIFT);
880 
881 	ASSERT(oldc <= newc);
882 
883 	mspp = kmem_zalloc(newc * sizeof (*mspp), KM_SLEEP);
884 
885 	if (oldc != 0) {
886 		bcopy(vd->vdev_ms, mspp, oldc * sizeof (*mspp));
887 		kmem_free(vd->vdev_ms, oldc * sizeof (*mspp));
888 	}
889 
890 	vd->vdev_ms = mspp;
891 	vd->vdev_ms_count = newc;
892 
893 	for (m = oldc; m < newc; m++) {
894 		uint64_t object = 0;
895 
896 		if (txg == 0) {
897 			error = dmu_read(mos, vd->vdev_ms_array,
898 			    m * sizeof (uint64_t), sizeof (uint64_t), &object,
899 			    DMU_READ_PREFETCH);
900 			if (error)
901 				return (error);
902 		}
903 
904 		error = metaslab_init(vd->vdev_mg, m, object, txg,
905 		    &(vd->vdev_ms[m]));
906 		if (error)
907 			return (error);
908 	}
909 
910 	if (txg == 0)
911 		spa_config_enter(spa, SCL_ALLOC, FTAG, RW_WRITER);
912 
913 	/*
914 	 * If the vdev is being removed we don't activate
915 	 * the metaslabs since we want to ensure that no new
916 	 * allocations are performed on this device.
917 	 */
918 	if (oldc == 0 && !vd->vdev_removing)
919 		metaslab_group_activate(vd->vdev_mg);
920 
921 	if (txg == 0)
922 		spa_config_exit(spa, SCL_ALLOC, FTAG);
923 
924 	return (0);
925 }
926 
927 void
928 vdev_metaslab_fini(vdev_t *vd)
929 {
930 	uint64_t m;
931 	uint64_t count = vd->vdev_ms_count;
932 
933 	if (vd->vdev_ms != NULL) {
934 		metaslab_group_passivate(vd->vdev_mg);
935 		for (m = 0; m < count; m++) {
936 			metaslab_t *msp = vd->vdev_ms[m];
937 
938 			if (msp != NULL)
939 				metaslab_fini(msp);
940 		}
941 		kmem_free(vd->vdev_ms, count * sizeof (metaslab_t *));
942 		vd->vdev_ms = NULL;
943 	}
944 }
945 
946 typedef struct vdev_probe_stats {
947 	boolean_t	vps_readable;
948 	boolean_t	vps_writeable;
949 	int		vps_flags;
950 } vdev_probe_stats_t;
951 
952 static void
953 vdev_probe_done(zio_t *zio)
954 {
955 	spa_t *spa = zio->io_spa;
956 	vdev_t *vd = zio->io_vd;
957 	vdev_probe_stats_t *vps = zio->io_private;
958 
959 	ASSERT(vd->vdev_probe_zio != NULL);
960 
961 	if (zio->io_type == ZIO_TYPE_READ) {
962 		if (zio->io_error == 0)
963 			vps->vps_readable = 1;
964 		if (zio->io_error == 0 && spa_writeable(spa)) {
965 			zio_nowait(zio_write_phys(vd->vdev_probe_zio, vd,
966 			    zio->io_offset, zio->io_size, zio->io_abd,
967 			    ZIO_CHECKSUM_OFF, vdev_probe_done, vps,
968 			    ZIO_PRIORITY_SYNC_WRITE, vps->vps_flags, B_TRUE));
969 		} else {
970 			abd_free(zio->io_abd);
971 		}
972 	} else if (zio->io_type == ZIO_TYPE_WRITE) {
973 		if (zio->io_error == 0)
974 			vps->vps_writeable = 1;
975 		abd_free(zio->io_abd);
976 	} else if (zio->io_type == ZIO_TYPE_NULL) {
977 		zio_t *pio;
978 
979 		vd->vdev_cant_read |= !vps->vps_readable;
980 		vd->vdev_cant_write |= !vps->vps_writeable;
981 
982 		if (vdev_readable(vd) &&
983 		    (vdev_writeable(vd) || !spa_writeable(spa))) {
984 			zio->io_error = 0;
985 		} else {
986 			ASSERT(zio->io_error != 0);
987 			zfs_ereport_post(FM_EREPORT_ZFS_PROBE_FAILURE,
988 			    spa, vd, NULL, 0, 0);
989 			zio->io_error = SET_ERROR(ENXIO);
990 		}
991 
992 		mutex_enter(&vd->vdev_probe_lock);
993 		ASSERT(vd->vdev_probe_zio == zio);
994 		vd->vdev_probe_zio = NULL;
995 		mutex_exit(&vd->vdev_probe_lock);
996 
997 		zio_link_t *zl = NULL;
998 		while ((pio = zio_walk_parents(zio, &zl)) != NULL)
999 			if (!vdev_accessible(vd, pio))
1000 				pio->io_error = SET_ERROR(ENXIO);
1001 
1002 		kmem_free(vps, sizeof (*vps));
1003 	}
1004 }
1005 
1006 /*
1007  * Determine whether this device is accessible.
1008  *
1009  * Read and write to several known locations: the pad regions of each
1010  * vdev label but the first, which we leave alone in case it contains
1011  * a VTOC.
1012  */
1013 zio_t *
1014 vdev_probe(vdev_t *vd, zio_t *zio)
1015 {
1016 	spa_t *spa = vd->vdev_spa;
1017 	vdev_probe_stats_t *vps = NULL;
1018 	zio_t *pio;
1019 
1020 	ASSERT(vd->vdev_ops->vdev_op_leaf);
1021 
1022 	/*
1023 	 * Don't probe the probe.
1024 	 */
1025 	if (zio && (zio->io_flags & ZIO_FLAG_PROBE))
1026 		return (NULL);
1027 
1028 	/*
1029 	 * To prevent 'probe storms' when a device fails, we create
1030 	 * just one probe i/o at a time.  All zios that want to probe
1031 	 * this vdev will become parents of the probe io.
1032 	 */
1033 	mutex_enter(&vd->vdev_probe_lock);
1034 
1035 	if ((pio = vd->vdev_probe_zio) == NULL) {
1036 		vps = kmem_zalloc(sizeof (*vps), KM_SLEEP);
1037 
1038 		vps->vps_flags = ZIO_FLAG_CANFAIL | ZIO_FLAG_PROBE |
1039 		    ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_AGGREGATE |
1040 		    ZIO_FLAG_TRYHARD;
1041 
1042 		if (spa_config_held(spa, SCL_ZIO, RW_WRITER)) {
1043 			/*
1044 			 * vdev_cant_read and vdev_cant_write can only
1045 			 * transition from TRUE to FALSE when we have the
1046 			 * SCL_ZIO lock as writer; otherwise they can only
1047 			 * transition from FALSE to TRUE.  This ensures that
1048 			 * any zio looking at these values can assume that
1049 			 * failures persist for the life of the I/O.  That's
1050 			 * important because when a device has intermittent
1051 			 * connectivity problems, we want to ensure that
1052 			 * they're ascribed to the device (ENXIO) and not
1053 			 * the zio (EIO).
1054 			 *
1055 			 * Since we hold SCL_ZIO as writer here, clear both
1056 			 * values so the probe can reevaluate from first
1057 			 * principles.
1058 			 */
1059 			vps->vps_flags |= ZIO_FLAG_CONFIG_WRITER;
1060 			vd->vdev_cant_read = B_FALSE;
1061 			vd->vdev_cant_write = B_FALSE;
1062 		}
1063 
1064 		vd->vdev_probe_zio = pio = zio_null(NULL, spa, vd,
1065 		    vdev_probe_done, vps,
1066 		    vps->vps_flags | ZIO_FLAG_DONT_PROPAGATE);
1067 
1068 		/*
1069 		 * We can't change the vdev state in this context, so we
1070 		 * kick off an async task to do it on our behalf.
1071 		 */
1072 		if (zio != NULL) {
1073 			vd->vdev_probe_wanted = B_TRUE;
1074 			spa_async_request(spa, SPA_ASYNC_PROBE);
1075 		}
1076 	}
1077 
1078 	if (zio != NULL)
1079 		zio_add_child(zio, pio);
1080 
1081 	mutex_exit(&vd->vdev_probe_lock);
1082 
1083 	if (vps == NULL) {
1084 		ASSERT(zio != NULL);
1085 		return (NULL);
1086 	}
1087 
1088 	for (int l = 1; l < VDEV_LABELS; l++) {
1089 		zio_nowait(zio_read_phys(pio, vd,
1090 		    vdev_label_offset(vd->vdev_psize, l,
1091 		    offsetof(vdev_label_t, vl_pad2)), VDEV_PAD_SIZE,
1092 		    abd_alloc_for_io(VDEV_PAD_SIZE, B_TRUE),
1093 		    ZIO_CHECKSUM_OFF, vdev_probe_done, vps,
1094 		    ZIO_PRIORITY_SYNC_READ, vps->vps_flags, B_TRUE));
1095 	}
1096 
1097 	if (zio == NULL)
1098 		return (pio);
1099 
1100 	zio_nowait(pio);
1101 	return (NULL);
1102 }
1103 
1104 static void
1105 vdev_open_child(void *arg)
1106 {
1107 	vdev_t *vd = arg;
1108 
1109 	vd->vdev_open_thread = curthread;
1110 	vd->vdev_open_error = vdev_open(vd);
1111 	vd->vdev_open_thread = NULL;
1112 }
1113 
1114 boolean_t
1115 vdev_uses_zvols(vdev_t *vd)
1116 {
1117 	if (vd->vdev_path && strncmp(vd->vdev_path, ZVOL_DIR,
1118 	    strlen(ZVOL_DIR)) == 0)
1119 		return (B_TRUE);
1120 	for (int c = 0; c < vd->vdev_children; c++)
1121 		if (vdev_uses_zvols(vd->vdev_child[c]))
1122 			return (B_TRUE);
1123 	return (B_FALSE);
1124 }
1125 
1126 void
1127 vdev_open_children(vdev_t *vd)
1128 {
1129 	taskq_t *tq;
1130 	int children = vd->vdev_children;
1131 
1132 	/*
1133 	 * in order to handle pools on top of zvols, do the opens
1134 	 * in a single thread so that the same thread holds the
1135 	 * spa_namespace_lock
1136 	 */
1137 	if (vdev_uses_zvols(vd)) {
1138 		for (int c = 0; c < children; c++)
1139 			vd->vdev_child[c]->vdev_open_error =
1140 			    vdev_open(vd->vdev_child[c]);
1141 		return;
1142 	}
1143 	tq = taskq_create("vdev_open", children, minclsyspri,
1144 	    children, children, TASKQ_PREPOPULATE);
1145 
1146 	for (int c = 0; c < children; c++)
1147 		VERIFY(taskq_dispatch(tq, vdev_open_child, vd->vdev_child[c],
1148 		    TQ_SLEEP) != NULL);
1149 
1150 	taskq_destroy(tq);
1151 }
1152 
1153 /*
1154  * Prepare a virtual device for access.
1155  */
1156 int
1157 vdev_open(vdev_t *vd)
1158 {
1159 	spa_t *spa = vd->vdev_spa;
1160 	int error;
1161 	uint64_t osize = 0;
1162 	uint64_t max_osize = 0;
1163 	uint64_t asize, max_asize, psize;
1164 	uint64_t ashift = 0;
1165 
1166 	ASSERT(vd->vdev_open_thread == curthread ||
1167 	    spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
1168 	ASSERT(vd->vdev_state == VDEV_STATE_CLOSED ||
1169 	    vd->vdev_state == VDEV_STATE_CANT_OPEN ||
1170 	    vd->vdev_state == VDEV_STATE_OFFLINE);
1171 
1172 	vd->vdev_stat.vs_aux = VDEV_AUX_NONE;
1173 	vd->vdev_cant_read = B_FALSE;
1174 	vd->vdev_cant_write = B_FALSE;
1175 	vd->vdev_min_asize = vdev_get_min_asize(vd);
1176 
1177 	/*
1178 	 * If this vdev is not removed, check its fault status.  If it's
1179 	 * faulted, bail out of the open.
1180 	 */
1181 	if (!vd->vdev_removed && vd->vdev_faulted) {
1182 		ASSERT(vd->vdev_children == 0);
1183 		ASSERT(vd->vdev_label_aux == VDEV_AUX_ERR_EXCEEDED ||
1184 		    vd->vdev_label_aux == VDEV_AUX_EXTERNAL);
1185 		vdev_set_state(vd, B_TRUE, VDEV_STATE_FAULTED,
1186 		    vd->vdev_label_aux);
1187 		return (SET_ERROR(ENXIO));
1188 	} else if (vd->vdev_offline) {
1189 		ASSERT(vd->vdev_children == 0);
1190 		vdev_set_state(vd, B_TRUE, VDEV_STATE_OFFLINE, VDEV_AUX_NONE);
1191 		return (SET_ERROR(ENXIO));
1192 	}
1193 
1194 	error = vd->vdev_ops->vdev_op_open(vd, &osize, &max_osize, &ashift);
1195 
1196 	/*
1197 	 * Reset the vdev_reopening flag so that we actually close
1198 	 * the vdev on error.
1199 	 */
1200 	vd->vdev_reopening = B_FALSE;
1201 	if (zio_injection_enabled && error == 0)
1202 		error = zio_handle_device_injection(vd, NULL, ENXIO);
1203 
1204 	if (error) {
1205 		if (vd->vdev_removed &&
1206 		    vd->vdev_stat.vs_aux != VDEV_AUX_OPEN_FAILED)
1207 			vd->vdev_removed = B_FALSE;
1208 
1209 		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
1210 		    vd->vdev_stat.vs_aux);
1211 		return (error);
1212 	}
1213 
1214 	vd->vdev_removed = B_FALSE;
1215 
1216 	/*
1217 	 * Recheck the faulted flag now that we have confirmed that
1218 	 * the vdev is accessible.  If we're faulted, bail.
1219 	 */
1220 	if (vd->vdev_faulted) {
1221 		ASSERT(vd->vdev_children == 0);
1222 		ASSERT(vd->vdev_label_aux == VDEV_AUX_ERR_EXCEEDED ||
1223 		    vd->vdev_label_aux == VDEV_AUX_EXTERNAL);
1224 		vdev_set_state(vd, B_TRUE, VDEV_STATE_FAULTED,
1225 		    vd->vdev_label_aux);
1226 		return (SET_ERROR(ENXIO));
1227 	}
1228 
1229 	if (vd->vdev_degraded) {
1230 		ASSERT(vd->vdev_children == 0);
1231 		vdev_set_state(vd, B_TRUE, VDEV_STATE_DEGRADED,
1232 		    VDEV_AUX_ERR_EXCEEDED);
1233 	} else {
1234 		vdev_set_state(vd, B_TRUE, VDEV_STATE_HEALTHY, 0);
1235 	}
1236 
1237 	/*
1238 	 * For hole or missing vdevs we just return success.
1239 	 */
1240 	if (vd->vdev_ishole || vd->vdev_ops == &vdev_missing_ops)
1241 		return (0);
1242 
1243 	for (int c = 0; c < vd->vdev_children; c++) {
1244 		if (vd->vdev_child[c]->vdev_state != VDEV_STATE_HEALTHY) {
1245 			vdev_set_state(vd, B_TRUE, VDEV_STATE_DEGRADED,
1246 			    VDEV_AUX_NONE);
1247 			break;
1248 		}
1249 	}
1250 
1251 	osize = P2ALIGN(osize, (uint64_t)sizeof (vdev_label_t));
1252 	max_osize = P2ALIGN(max_osize, (uint64_t)sizeof (vdev_label_t));
1253 
1254 	if (vd->vdev_children == 0) {
1255 		if (osize < SPA_MINDEVSIZE) {
1256 			vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
1257 			    VDEV_AUX_TOO_SMALL);
1258 			return (SET_ERROR(EOVERFLOW));
1259 		}
1260 		psize = osize;
1261 		asize = osize - (VDEV_LABEL_START_SIZE + VDEV_LABEL_END_SIZE);
1262 		max_asize = max_osize - (VDEV_LABEL_START_SIZE +
1263 		    VDEV_LABEL_END_SIZE);
1264 	} else {
1265 		if (vd->vdev_parent != NULL && osize < SPA_MINDEVSIZE -
1266 		    (VDEV_LABEL_START_SIZE + VDEV_LABEL_END_SIZE)) {
1267 			vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
1268 			    VDEV_AUX_TOO_SMALL);
1269 			return (SET_ERROR(EOVERFLOW));
1270 		}
1271 		psize = 0;
1272 		asize = osize;
1273 		max_asize = max_osize;
1274 	}
1275 
1276 	vd->vdev_psize = psize;
1277 
1278 	/*
1279 	 * Make sure the allocatable size hasn't shrunk too much.
1280 	 */
1281 	if (asize < vd->vdev_min_asize) {
1282 		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
1283 		    VDEV_AUX_BAD_LABEL);
1284 		return (SET_ERROR(EINVAL));
1285 	}
1286 
1287 	if (vd->vdev_asize == 0) {
1288 		/*
1289 		 * This is the first-ever open, so use the computed values.
1290 		 * For testing purposes, a higher ashift can be requested.
1291 		 */
1292 		vd->vdev_asize = asize;
1293 		vd->vdev_max_asize = max_asize;
1294 		vd->vdev_ashift = MAX(ashift, vd->vdev_ashift);
1295 	} else {
1296 		/*
1297 		 * Detect if the alignment requirement has increased.
1298 		 * We don't want to make the pool unavailable, just
1299 		 * issue a warning instead.
1300 		 */
1301 		if (ashift > vd->vdev_top->vdev_ashift &&
1302 		    vd->vdev_ops->vdev_op_leaf) {
1303 			cmn_err(CE_WARN,
1304 			    "Disk, '%s', has a block alignment that is "
1305 			    "larger than the pool's alignment\n",
1306 			    vd->vdev_path);
1307 		}
1308 		vd->vdev_max_asize = max_asize;
1309 	}
1310 
1311 	/*
1312 	 * If all children are healthy we update asize if either:
1313 	 * The asize has increased, due to a device expansion caused by dynamic
1314 	 * LUN growth or vdev replacement, and automatic expansion is enabled;
1315 	 * making the additional space available.
1316 	 *
1317 	 * The asize has decreased, due to a device shrink usually caused by a
1318 	 * vdev replace with a smaller device. This ensures that calculations
1319 	 * based of max_asize and asize e.g. esize are always valid. It's safe
1320 	 * to do this as we've already validated that asize is greater than
1321 	 * vdev_min_asize.
1322 	 */
1323 	if (vd->vdev_state == VDEV_STATE_HEALTHY &&
1324 	    ((asize > vd->vdev_asize &&
1325 	    (vd->vdev_expanding || spa->spa_autoexpand)) ||
1326 	    (asize < vd->vdev_asize)))
1327 		vd->vdev_asize = asize;
1328 
1329 	vdev_set_min_asize(vd);
1330 
1331 	/*
1332 	 * Ensure we can issue some IO before declaring the
1333 	 * vdev open for business.
1334 	 */
1335 	if (vd->vdev_ops->vdev_op_leaf &&
1336 	    (error = zio_wait(vdev_probe(vd, NULL))) != 0) {
1337 		vdev_set_state(vd, B_TRUE, VDEV_STATE_FAULTED,
1338 		    VDEV_AUX_ERR_EXCEEDED);
1339 		return (error);
1340 	}
1341 
1342 	/*
1343 	 * Track the min and max ashift values for normal data devices.
1344 	 */
1345 	if (vd->vdev_top == vd && vd->vdev_ashift != 0 &&
1346 	    !vd->vdev_islog && vd->vdev_aux == NULL) {
1347 		if (vd->vdev_ashift > spa->spa_max_ashift)
1348 			spa->spa_max_ashift = vd->vdev_ashift;
1349 		if (vd->vdev_ashift < spa->spa_min_ashift)
1350 			spa->spa_min_ashift = vd->vdev_ashift;
1351 	}
1352 
1353 	/*
1354 	 * If a leaf vdev has a DTL, and seems healthy, then kick off a
1355 	 * resilver.  But don't do this if we are doing a reopen for a scrub,
1356 	 * since this would just restart the scrub we are already doing.
1357 	 */
1358 	if (vd->vdev_ops->vdev_op_leaf && !spa->spa_scrub_reopen &&
1359 	    vdev_resilver_needed(vd, NULL, NULL))
1360 		spa_async_request(spa, SPA_ASYNC_RESILVER);
1361 
1362 	return (0);
1363 }
1364 
1365 /*
1366  * Called once the vdevs are all opened, this routine validates the label
1367  * contents.  This needs to be done before vdev_load() so that we don't
1368  * inadvertently do repair I/Os to the wrong device.
1369  *
1370  * If 'strict' is false ignore the spa guid check. This is necessary because
1371  * if the machine crashed during a re-guid the new guid might have been written
1372  * to all of the vdev labels, but not the cached config. The strict check
1373  * will be performed when the pool is opened again using the mos config.
1374  *
1375  * This function will only return failure if one of the vdevs indicates that it
1376  * has since been destroyed or exported.  This is only possible if
1377  * /etc/zfs/zpool.cache was readonly at the time.  Otherwise, the vdev state
1378  * will be updated but the function will return 0.
1379  */
1380 int
1381 vdev_validate(vdev_t *vd, boolean_t strict)
1382 {
1383 	spa_t *spa = vd->vdev_spa;
1384 	nvlist_t *label;
1385 	uint64_t guid = 0, top_guid;
1386 	uint64_t state;
1387 
1388 	for (int c = 0; c < vd->vdev_children; c++)
1389 		if (vdev_validate(vd->vdev_child[c], strict) != 0)
1390 			return (SET_ERROR(EBADF));
1391 
1392 	/*
1393 	 * If the device has already failed, or was marked offline, don't do
1394 	 * any further validation.  Otherwise, label I/O will fail and we will
1395 	 * overwrite the previous state.
1396 	 */
1397 	if (vd->vdev_ops->vdev_op_leaf && vdev_readable(vd)) {
1398 		uint64_t aux_guid = 0;
1399 		nvlist_t *nvl;
1400 		uint64_t txg = spa_last_synced_txg(spa) != 0 ?
1401 		    spa_last_synced_txg(spa) : -1ULL;
1402 
1403 		if ((label = vdev_label_read_config(vd, txg)) == NULL) {
1404 			vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
1405 			    VDEV_AUX_BAD_LABEL);
1406 			return (0);
1407 		}
1408 
1409 		/*
1410 		 * Determine if this vdev has been split off into another
1411 		 * pool.  If so, then refuse to open it.
1412 		 */
1413 		if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_SPLIT_GUID,
1414 		    &aux_guid) == 0 && aux_guid == spa_guid(spa)) {
1415 			vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
1416 			    VDEV_AUX_SPLIT_POOL);
1417 			nvlist_free(label);
1418 			return (0);
1419 		}
1420 
1421 		if (strict && (nvlist_lookup_uint64(label,
1422 		    ZPOOL_CONFIG_POOL_GUID, &guid) != 0 ||
1423 		    guid != spa_guid(spa))) {
1424 			vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
1425 			    VDEV_AUX_CORRUPT_DATA);
1426 			nvlist_free(label);
1427 			return (0);
1428 		}
1429 
1430 		if (nvlist_lookup_nvlist(label, ZPOOL_CONFIG_VDEV_TREE, &nvl)
1431 		    != 0 || nvlist_lookup_uint64(nvl, ZPOOL_CONFIG_ORIG_GUID,
1432 		    &aux_guid) != 0)
1433 			aux_guid = 0;
1434 
1435 		/*
1436 		 * If this vdev just became a top-level vdev because its
1437 		 * sibling was detached, it will have adopted the parent's
1438 		 * vdev guid -- but the label may or may not be on disk yet.
1439 		 * Fortunately, either version of the label will have the
1440 		 * same top guid, so if we're a top-level vdev, we can
1441 		 * safely compare to that instead.
1442 		 *
1443 		 * If we split this vdev off instead, then we also check the
1444 		 * original pool's guid.  We don't want to consider the vdev
1445 		 * corrupt if it is partway through a split operation.
1446 		 */
1447 		if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID,
1448 		    &guid) != 0 ||
1449 		    nvlist_lookup_uint64(label, ZPOOL_CONFIG_TOP_GUID,
1450 		    &top_guid) != 0 ||
1451 		    ((vd->vdev_guid != guid && vd->vdev_guid != aux_guid) &&
1452 		    (vd->vdev_guid != top_guid || vd != vd->vdev_top))) {
1453 			vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
1454 			    VDEV_AUX_CORRUPT_DATA);
1455 			nvlist_free(label);
1456 			return (0);
1457 		}
1458 
1459 		if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE,
1460 		    &state) != 0) {
1461 			vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
1462 			    VDEV_AUX_CORRUPT_DATA);
1463 			nvlist_free(label);
1464 			return (0);
1465 		}
1466 
1467 		nvlist_free(label);
1468 
1469 		/*
1470 		 * If this is a verbatim import, no need to check the
1471 		 * state of the pool.
1472 		 */
1473 		if (!(spa->spa_import_flags & ZFS_IMPORT_VERBATIM) &&
1474 		    spa_load_state(spa) == SPA_LOAD_OPEN &&
1475 		    state != POOL_STATE_ACTIVE)
1476 			return (SET_ERROR(EBADF));
1477 
1478 		/*
1479 		 * If we were able to open and validate a vdev that was
1480 		 * previously marked permanently unavailable, clear that state
1481 		 * now.
1482 		 */
1483 		if (vd->vdev_not_present)
1484 			vd->vdev_not_present = 0;
1485 	}
1486 
1487 	return (0);
1488 }
1489 
1490 /*
1491  * Close a virtual device.
1492  */
1493 void
1494 vdev_close(vdev_t *vd)
1495 {
1496 	spa_t *spa = vd->vdev_spa;
1497 	vdev_t *pvd = vd->vdev_parent;
1498 
1499 	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
1500 
1501 	/*
1502 	 * If our parent is reopening, then we are as well, unless we are
1503 	 * going offline.
1504 	 */
1505 	if (pvd != NULL && pvd->vdev_reopening)
1506 		vd->vdev_reopening = (pvd->vdev_reopening && !vd->vdev_offline);
1507 
1508 	vd->vdev_ops->vdev_op_close(vd);
1509 
1510 	vdev_cache_purge(vd);
1511 
1512 	/*
1513 	 * We record the previous state before we close it, so that if we are
1514 	 * doing a reopen(), we don't generate FMA ereports if we notice that
1515 	 * it's still faulted.
1516 	 */
1517 	vd->vdev_prevstate = vd->vdev_state;
1518 
1519 	if (vd->vdev_offline)
1520 		vd->vdev_state = VDEV_STATE_OFFLINE;
1521 	else
1522 		vd->vdev_state = VDEV_STATE_CLOSED;
1523 	vd->vdev_stat.vs_aux = VDEV_AUX_NONE;
1524 }
1525 
1526 void
1527 vdev_hold(vdev_t *vd)
1528 {
1529 	spa_t *spa = vd->vdev_spa;
1530 
1531 	ASSERT(spa_is_root(spa));
1532 	if (spa->spa_state == POOL_STATE_UNINITIALIZED)
1533 		return;
1534 
1535 	for (int c = 0; c < vd->vdev_children; c++)
1536 		vdev_hold(vd->vdev_child[c]);
1537 
1538 	if (vd->vdev_ops->vdev_op_leaf)
1539 		vd->vdev_ops->vdev_op_hold(vd);
1540 }
1541 
1542 void
1543 vdev_rele(vdev_t *vd)
1544 {
1545 	spa_t *spa = vd->vdev_spa;
1546 
1547 	ASSERT(spa_is_root(spa));
1548 	for (int c = 0; c < vd->vdev_children; c++)
1549 		vdev_rele(vd->vdev_child[c]);
1550 
1551 	if (vd->vdev_ops->vdev_op_leaf)
1552 		vd->vdev_ops->vdev_op_rele(vd);
1553 }
1554 
1555 /*
1556  * Reopen all interior vdevs and any unopened leaves.  We don't actually
1557  * reopen leaf vdevs which had previously been opened as they might deadlock
1558  * on the spa_config_lock.  Instead we only obtain the leaf's physical size.
1559  * If the leaf has never been opened then open it, as usual.
1560  */
1561 void
1562 vdev_reopen(vdev_t *vd)
1563 {
1564 	spa_t *spa = vd->vdev_spa;
1565 
1566 	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
1567 
1568 	/* set the reopening flag unless we're taking the vdev offline */
1569 	vd->vdev_reopening = !vd->vdev_offline;
1570 	vdev_close(vd);
1571 	(void) vdev_open(vd);
1572 
1573 	/*
1574 	 * Call vdev_validate() here to make sure we have the same device.
1575 	 * Otherwise, a device with an invalid label could be successfully
1576 	 * opened in response to vdev_reopen().
1577 	 */
1578 	if (vd->vdev_aux) {
1579 		(void) vdev_validate_aux(vd);
1580 		if (vdev_readable(vd) && vdev_writeable(vd) &&
1581 		    vd->vdev_aux == &spa->spa_l2cache &&
1582 		    !l2arc_vdev_present(vd))
1583 			l2arc_add_vdev(spa, vd);
1584 	} else {
1585 		(void) vdev_validate(vd, B_TRUE);
1586 	}
1587 
1588 	/*
1589 	 * Reassess parent vdev's health.
1590 	 */
1591 	vdev_propagate_state(vd);
1592 }
1593 
1594 int
1595 vdev_create(vdev_t *vd, uint64_t txg, boolean_t isreplacing)
1596 {
1597 	int error;
1598 
1599 	/*
1600 	 * Normally, partial opens (e.g. of a mirror) are allowed.
1601 	 * For a create, however, we want to fail the request if
1602 	 * there are any components we can't open.
1603 	 */
1604 	error = vdev_open(vd);
1605 
1606 	if (error || vd->vdev_state != VDEV_STATE_HEALTHY) {
1607 		vdev_close(vd);
1608 		return (error ? error : ENXIO);
1609 	}
1610 
1611 	/*
1612 	 * Recursively load DTLs and initialize all labels.
1613 	 */
1614 	if ((error = vdev_dtl_load(vd)) != 0 ||
1615 	    (error = vdev_label_init(vd, txg, isreplacing ?
1616 	    VDEV_LABEL_REPLACE : VDEV_LABEL_CREATE)) != 0) {
1617 		vdev_close(vd);
1618 		return (error);
1619 	}
1620 
1621 	return (0);
1622 }
1623 
1624 void
1625 vdev_metaslab_set_size(vdev_t *vd)
1626 {
1627 	/*
1628 	 * Aim for roughly metaslabs_per_vdev (default 200) metaslabs per vdev.
1629 	 */
1630 	vd->vdev_ms_shift = highbit64(vd->vdev_asize / metaslabs_per_vdev);
1631 	vd->vdev_ms_shift = MAX(vd->vdev_ms_shift, SPA_MAXBLOCKSHIFT);
1632 }
1633 
1634 void
1635 vdev_dirty(vdev_t *vd, int flags, void *arg, uint64_t txg)
1636 {
1637 	ASSERT(vd == vd->vdev_top);
1638 	ASSERT(!vd->vdev_ishole);
1639 	ASSERT(ISP2(flags));
1640 	ASSERT(spa_writeable(vd->vdev_spa));
1641 
1642 	if (flags & VDD_METASLAB)
1643 		(void) txg_list_add(&vd->vdev_ms_list, arg, txg);
1644 
1645 	if (flags & VDD_DTL)
1646 		(void) txg_list_add(&vd->vdev_dtl_list, arg, txg);
1647 
1648 	(void) txg_list_add(&vd->vdev_spa->spa_vdev_txg_list, vd, txg);
1649 }
1650 
1651 void
1652 vdev_dirty_leaves(vdev_t *vd, int flags, uint64_t txg)
1653 {
1654 	for (int c = 0; c < vd->vdev_children; c++)
1655 		vdev_dirty_leaves(vd->vdev_child[c], flags, txg);
1656 
1657 	if (vd->vdev_ops->vdev_op_leaf)
1658 		vdev_dirty(vd->vdev_top, flags, vd, txg);
1659 }
1660 
1661 /*
1662  * DTLs.
1663  *
1664  * A vdev's DTL (dirty time log) is the set of transaction groups for which
1665  * the vdev has less than perfect replication.  There are four kinds of DTL:
1666  *
1667  * DTL_MISSING: txgs for which the vdev has no valid copies of the data
1668  *
1669  * DTL_PARTIAL: txgs for which data is available, but not fully replicated
1670  *
1671  * DTL_SCRUB: the txgs that could not be repaired by the last scrub; upon
1672  *	scrub completion, DTL_SCRUB replaces DTL_MISSING in the range of
1673  *	txgs that was scrubbed.
1674  *
1675  * DTL_OUTAGE: txgs which cannot currently be read, whether due to
1676  *	persistent errors or just some device being offline.
1677  *	Unlike the other three, the DTL_OUTAGE map is not generally
1678  *	maintained; it's only computed when needed, typically to
1679  *	determine whether a device can be detached.
1680  *
1681  * For leaf vdevs, DTL_MISSING and DTL_PARTIAL are identical: the device
1682  * either has the data or it doesn't.
1683  *
1684  * For interior vdevs such as mirror and RAID-Z the picture is more complex.
1685  * A vdev's DTL_PARTIAL is the union of its children's DTL_PARTIALs, because
1686  * if any child is less than fully replicated, then so is its parent.
1687  * A vdev's DTL_MISSING is a modified union of its children's DTL_MISSINGs,
1688  * comprising only those txgs which appear in 'maxfaults' or more children;
1689  * those are the txgs we don't have enough replication to read.  For example,
1690  * double-parity RAID-Z can tolerate up to two missing devices (maxfaults == 2);
1691  * thus, its DTL_MISSING consists of the set of txgs that appear in more than
1692  * two child DTL_MISSING maps.
1693  *
1694  * It should be clear from the above that to compute the DTLs and outage maps
1695  * for all vdevs, it suffices to know just the leaf vdevs' DTL_MISSING maps.
1696  * Therefore, that is all we keep on disk.  When loading the pool, or after
1697  * a configuration change, we generate all other DTLs from first principles.
1698  */
1699 void
1700 vdev_dtl_dirty(vdev_t *vd, vdev_dtl_type_t t, uint64_t txg, uint64_t size)
1701 {
1702 	range_tree_t *rt = vd->vdev_dtl[t];
1703 
1704 	ASSERT(t < DTL_TYPES);
1705 	ASSERT(vd != vd->vdev_spa->spa_root_vdev);
1706 	ASSERT(spa_writeable(vd->vdev_spa));
1707 
1708 	mutex_enter(rt->rt_lock);
1709 	if (!range_tree_contains(rt, txg, size))
1710 		range_tree_add(rt, txg, size);
1711 	mutex_exit(rt->rt_lock);
1712 }
1713 
1714 boolean_t
1715 vdev_dtl_contains(vdev_t *vd, vdev_dtl_type_t t, uint64_t txg, uint64_t size)
1716 {
1717 	range_tree_t *rt = vd->vdev_dtl[t];
1718 	boolean_t dirty = B_FALSE;
1719 
1720 	ASSERT(t < DTL_TYPES);
1721 	ASSERT(vd != vd->vdev_spa->spa_root_vdev);
1722 
1723 	mutex_enter(rt->rt_lock);
1724 	if (range_tree_space(rt) != 0)
1725 		dirty = range_tree_contains(rt, txg, size);
1726 	mutex_exit(rt->rt_lock);
1727 
1728 	return (dirty);
1729 }
1730 
1731 boolean_t
1732 vdev_dtl_empty(vdev_t *vd, vdev_dtl_type_t t)
1733 {
1734 	range_tree_t *rt = vd->vdev_dtl[t];
1735 	boolean_t empty;
1736 
1737 	mutex_enter(rt->rt_lock);
1738 	empty = (range_tree_space(rt) == 0);
1739 	mutex_exit(rt->rt_lock);
1740 
1741 	return (empty);
1742 }
1743 
1744 /*
1745  * Returns the lowest txg in the DTL range.
1746  */
1747 static uint64_t
1748 vdev_dtl_min(vdev_t *vd)
1749 {
1750 	range_seg_t *rs;
1751 
1752 	ASSERT(MUTEX_HELD(&vd->vdev_dtl_lock));
1753 	ASSERT3U(range_tree_space(vd->vdev_dtl[DTL_MISSING]), !=, 0);
1754 	ASSERT0(vd->vdev_children);
1755 
1756 	rs = avl_first(&vd->vdev_dtl[DTL_MISSING]->rt_root);
1757 	return (rs->rs_start - 1);
1758 }
1759 
1760 /*
1761  * Returns the highest txg in the DTL.
1762  */
1763 static uint64_t
1764 vdev_dtl_max(vdev_t *vd)
1765 {
1766 	range_seg_t *rs;
1767 
1768 	ASSERT(MUTEX_HELD(&vd->vdev_dtl_lock));
1769 	ASSERT3U(range_tree_space(vd->vdev_dtl[DTL_MISSING]), !=, 0);
1770 	ASSERT0(vd->vdev_children);
1771 
1772 	rs = avl_last(&vd->vdev_dtl[DTL_MISSING]->rt_root);
1773 	return (rs->rs_end);
1774 }
1775 
1776 /*
1777  * Determine if a resilvering vdev should remove any DTL entries from
1778  * its range. If the vdev was resilvering for the entire duration of the
1779  * scan then it should excise that range from its DTLs. Otherwise, this
1780  * vdev is considered partially resilvered and should leave its DTL
1781  * entries intact. The comment in vdev_dtl_reassess() describes how we
1782  * excise the DTLs.
1783  */
1784 static boolean_t
1785 vdev_dtl_should_excise(vdev_t *vd)
1786 {
1787 	spa_t *spa = vd->vdev_spa;
1788 	dsl_scan_t *scn = spa->spa_dsl_pool->dp_scan;
1789 
1790 	ASSERT0(scn->scn_phys.scn_errors);
1791 	ASSERT0(vd->vdev_children);
1792 
1793 	if (vd->vdev_state < VDEV_STATE_DEGRADED)
1794 		return (B_FALSE);
1795 
1796 	if (vd->vdev_resilver_txg == 0 ||
1797 	    range_tree_space(vd->vdev_dtl[DTL_MISSING]) == 0)
1798 		return (B_TRUE);
1799 
1800 	/*
1801 	 * When a resilver is initiated the scan will assign the scn_max_txg
1802 	 * value to the highest txg value that exists in all DTLs. If this
1803 	 * device's max DTL is not part of this scan (i.e. it is not in
1804 	 * the range (scn_min_txg, scn_max_txg] then it is not eligible
1805 	 * for excision.
1806 	 */
1807 	if (vdev_dtl_max(vd) <= scn->scn_phys.scn_max_txg) {
1808 		ASSERT3U(scn->scn_phys.scn_min_txg, <=, vdev_dtl_min(vd));
1809 		ASSERT3U(scn->scn_phys.scn_min_txg, <, vd->vdev_resilver_txg);
1810 		ASSERT3U(vd->vdev_resilver_txg, <=, scn->scn_phys.scn_max_txg);
1811 		return (B_TRUE);
1812 	}
1813 	return (B_FALSE);
1814 }
1815 
1816 /*
1817  * Reassess DTLs after a config change or scrub completion.
1818  */
1819 void
1820 vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg, int scrub_done)
1821 {
1822 	spa_t *spa = vd->vdev_spa;
1823 	avl_tree_t reftree;
1824 	int minref;
1825 
1826 	ASSERT(spa_config_held(spa, SCL_ALL, RW_READER) != 0);
1827 
1828 	for (int c = 0; c < vd->vdev_children; c++)
1829 		vdev_dtl_reassess(vd->vdev_child[c], txg,
1830 		    scrub_txg, scrub_done);
1831 
1832 	if (vd == spa->spa_root_vdev || vd->vdev_ishole || vd->vdev_aux)
1833 		return;
1834 
1835 	if (vd->vdev_ops->vdev_op_leaf) {
1836 		dsl_scan_t *scn = spa->spa_dsl_pool->dp_scan;
1837 
1838 		mutex_enter(&vd->vdev_dtl_lock);
1839 
1840 		/*
1841 		 * If we've completed a scan cleanly then determine
1842 		 * if this vdev should remove any DTLs. We only want to
1843 		 * excise regions on vdevs that were available during
1844 		 * the entire duration of this scan.
1845 		 */
1846 		if (scrub_txg != 0 &&
1847 		    (spa->spa_scrub_started ||
1848 		    (scn != NULL && scn->scn_phys.scn_errors == 0)) &&
1849 		    vdev_dtl_should_excise(vd)) {
1850 			/*
1851 			 * We completed a scrub up to scrub_txg.  If we
1852 			 * did it without rebooting, then the scrub dtl
1853 			 * will be valid, so excise the old region and
1854 			 * fold in the scrub dtl.  Otherwise, leave the
1855 			 * dtl as-is if there was an error.
1856 			 *
1857 			 * There's little trick here: to excise the beginning
1858 			 * of the DTL_MISSING map, we put it into a reference
1859 			 * tree and then add a segment with refcnt -1 that
1860 			 * covers the range [0, scrub_txg).  This means
1861 			 * that each txg in that range has refcnt -1 or 0.
1862 			 * We then add DTL_SCRUB with a refcnt of 2, so that
1863 			 * entries in the range [0, scrub_txg) will have a
1864 			 * positive refcnt -- either 1 or 2.  We then convert
1865 			 * the reference tree into the new DTL_MISSING map.
1866 			 */
1867 			space_reftree_create(&reftree);
1868 			space_reftree_add_map(&reftree,
1869 			    vd->vdev_dtl[DTL_MISSING], 1);
1870 			space_reftree_add_seg(&reftree, 0, scrub_txg, -1);
1871 			space_reftree_add_map(&reftree,
1872 			    vd->vdev_dtl[DTL_SCRUB], 2);
1873 			space_reftree_generate_map(&reftree,
1874 			    vd->vdev_dtl[DTL_MISSING], 1);
1875 			space_reftree_destroy(&reftree);
1876 		}
1877 		range_tree_vacate(vd->vdev_dtl[DTL_PARTIAL], NULL, NULL);
1878 		range_tree_walk(vd->vdev_dtl[DTL_MISSING],
1879 		    range_tree_add, vd->vdev_dtl[DTL_PARTIAL]);
1880 		if (scrub_done)
1881 			range_tree_vacate(vd->vdev_dtl[DTL_SCRUB], NULL, NULL);
1882 		range_tree_vacate(vd->vdev_dtl[DTL_OUTAGE], NULL, NULL);
1883 		if (!vdev_readable(vd))
1884 			range_tree_add(vd->vdev_dtl[DTL_OUTAGE], 0, -1ULL);
1885 		else
1886 			range_tree_walk(vd->vdev_dtl[DTL_MISSING],
1887 			    range_tree_add, vd->vdev_dtl[DTL_OUTAGE]);
1888 
1889 		/*
1890 		 * If the vdev was resilvering and no longer has any
1891 		 * DTLs then reset its resilvering flag.
1892 		 */
1893 		if (vd->vdev_resilver_txg != 0 &&
1894 		    range_tree_space(vd->vdev_dtl[DTL_MISSING]) == 0 &&
1895 		    range_tree_space(vd->vdev_dtl[DTL_OUTAGE]) == 0)
1896 			vd->vdev_resilver_txg = 0;
1897 
1898 		mutex_exit(&vd->vdev_dtl_lock);
1899 
1900 		if (txg != 0)
1901 			vdev_dirty(vd->vdev_top, VDD_DTL, vd, txg);
1902 		return;
1903 	}
1904 
1905 	mutex_enter(&vd->vdev_dtl_lock);
1906 	for (int t = 0; t < DTL_TYPES; t++) {
1907 		/* account for child's outage in parent's missing map */
1908 		int s = (t == DTL_MISSING) ? DTL_OUTAGE: t;
1909 		if (t == DTL_SCRUB)
1910 			continue;			/* leaf vdevs only */
1911 		if (t == DTL_PARTIAL)
1912 			minref = 1;			/* i.e. non-zero */
1913 		else if (vd->vdev_nparity != 0)
1914 			minref = vd->vdev_nparity + 1;	/* RAID-Z */
1915 		else
1916 			minref = vd->vdev_children;	/* any kind of mirror */
1917 		space_reftree_create(&reftree);
1918 		for (int c = 0; c < vd->vdev_children; c++) {
1919 			vdev_t *cvd = vd->vdev_child[c];
1920 			mutex_enter(&cvd->vdev_dtl_lock);
1921 			space_reftree_add_map(&reftree, cvd->vdev_dtl[s], 1);
1922 			mutex_exit(&cvd->vdev_dtl_lock);
1923 		}
1924 		space_reftree_generate_map(&reftree, vd->vdev_dtl[t], minref);
1925 		space_reftree_destroy(&reftree);
1926 	}
1927 	mutex_exit(&vd->vdev_dtl_lock);
1928 }
1929 
1930 int
1931 vdev_dtl_load(vdev_t *vd)
1932 {
1933 	spa_t *spa = vd->vdev_spa;
1934 	objset_t *mos = spa->spa_meta_objset;
1935 	int error = 0;
1936 
1937 	if (vd->vdev_ops->vdev_op_leaf && vd->vdev_dtl_object != 0) {
1938 		ASSERT(!vd->vdev_ishole);
1939 
1940 		error = space_map_open(&vd->vdev_dtl_sm, mos,
1941 		    vd->vdev_dtl_object, 0, -1ULL, 0, &vd->vdev_dtl_lock);
1942 		if (error)
1943 			return (error);
1944 		ASSERT(vd->vdev_dtl_sm != NULL);
1945 
1946 		mutex_enter(&vd->vdev_dtl_lock);
1947 
1948 		/*
1949 		 * Now that we've opened the space_map we need to update
1950 		 * the in-core DTL.
1951 		 */
1952 		space_map_update(vd->vdev_dtl_sm);
1953 
1954 		error = space_map_load(vd->vdev_dtl_sm,
1955 		    vd->vdev_dtl[DTL_MISSING], SM_ALLOC);
1956 		mutex_exit(&vd->vdev_dtl_lock);
1957 
1958 		return (error);
1959 	}
1960 
1961 	for (int c = 0; c < vd->vdev_children; c++) {
1962 		error = vdev_dtl_load(vd->vdev_child[c]);
1963 		if (error != 0)
1964 			break;
1965 	}
1966 
1967 	return (error);
1968 }
1969 
1970 void
1971 vdev_destroy_unlink_zap(vdev_t *vd, uint64_t zapobj, dmu_tx_t *tx)
1972 {
1973 	spa_t *spa = vd->vdev_spa;
1974 
1975 	VERIFY0(zap_destroy(spa->spa_meta_objset, zapobj, tx));
1976 	VERIFY0(zap_remove_int(spa->spa_meta_objset, spa->spa_all_vdev_zaps,
1977 	    zapobj, tx));
1978 }
1979 
1980 uint64_t
1981 vdev_create_link_zap(vdev_t *vd, dmu_tx_t *tx)
1982 {
1983 	spa_t *spa = vd->vdev_spa;
1984 	uint64_t zap = zap_create(spa->spa_meta_objset, DMU_OTN_ZAP_METADATA,
1985 	    DMU_OT_NONE, 0, tx);
1986 
1987 	ASSERT(zap != 0);
1988 	VERIFY0(zap_add_int(spa->spa_meta_objset, spa->spa_all_vdev_zaps,
1989 	    zap, tx));
1990 
1991 	return (zap);
1992 }
1993 
1994 void
1995 vdev_construct_zaps(vdev_t *vd, dmu_tx_t *tx)
1996 {
1997 	if (vd->vdev_ops != &vdev_hole_ops &&
1998 	    vd->vdev_ops != &vdev_missing_ops &&
1999 	    vd->vdev_ops != &vdev_root_ops &&
2000 	    !vd->vdev_top->vdev_removing) {
2001 		if (vd->vdev_ops->vdev_op_leaf && vd->vdev_leaf_zap == 0) {
2002 			vd->vdev_leaf_zap = vdev_create_link_zap(vd, tx);
2003 		}
2004 		if (vd == vd->vdev_top && vd->vdev_top_zap == 0) {
2005 			vd->vdev_top_zap = vdev_create_link_zap(vd, tx);
2006 		}
2007 	}
2008 	for (uint64_t i = 0; i < vd->vdev_children; i++) {
2009 		vdev_construct_zaps(vd->vdev_child[i], tx);
2010 	}
2011 }
2012 
2013 void
2014 vdev_dtl_sync(vdev_t *vd, uint64_t txg)
2015 {
2016 	spa_t *spa = vd->vdev_spa;
2017 	range_tree_t *rt = vd->vdev_dtl[DTL_MISSING];
2018 	objset_t *mos = spa->spa_meta_objset;
2019 	range_tree_t *rtsync;
2020 	kmutex_t rtlock;
2021 	dmu_tx_t *tx;
2022 	uint64_t object = space_map_object(vd->vdev_dtl_sm);
2023 
2024 	ASSERT(!vd->vdev_ishole);
2025 	ASSERT(vd->vdev_ops->vdev_op_leaf);
2026 
2027 	tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
2028 
2029 	if (vd->vdev_detached || vd->vdev_top->vdev_removing) {
2030 		mutex_enter(&vd->vdev_dtl_lock);
2031 		space_map_free(vd->vdev_dtl_sm, tx);
2032 		space_map_close(vd->vdev_dtl_sm);
2033 		vd->vdev_dtl_sm = NULL;
2034 		mutex_exit(&vd->vdev_dtl_lock);
2035 
2036 		/*
2037 		 * We only destroy the leaf ZAP for detached leaves or for
2038 		 * removed log devices. Removed data devices handle leaf ZAP
2039 		 * cleanup later, once cancellation is no longer possible.
2040 		 */
2041 		if (vd->vdev_leaf_zap != 0 && (vd->vdev_detached ||
2042 		    vd->vdev_top->vdev_islog)) {
2043 			vdev_destroy_unlink_zap(vd, vd->vdev_leaf_zap, tx);
2044 			vd->vdev_leaf_zap = 0;
2045 		}
2046 
2047 		dmu_tx_commit(tx);
2048 		return;
2049 	}
2050 
2051 	if (vd->vdev_dtl_sm == NULL) {
2052 		uint64_t new_object;
2053 
2054 		new_object = space_map_alloc(mos, tx);
2055 		VERIFY3U(new_object, !=, 0);
2056 
2057 		VERIFY0(space_map_open(&vd->vdev_dtl_sm, mos, new_object,
2058 		    0, -1ULL, 0, &vd->vdev_dtl_lock));
2059 		ASSERT(vd->vdev_dtl_sm != NULL);
2060 	}
2061 
2062 	mutex_init(&rtlock, NULL, MUTEX_DEFAULT, NULL);
2063 
2064 	rtsync = range_tree_create(NULL, NULL, &rtlock);
2065 
2066 	mutex_enter(&rtlock);
2067 
2068 	mutex_enter(&vd->vdev_dtl_lock);
2069 	range_tree_walk(rt, range_tree_add, rtsync);
2070 	mutex_exit(&vd->vdev_dtl_lock);
2071 
2072 	space_map_truncate(vd->vdev_dtl_sm, tx);
2073 	space_map_write(vd->vdev_dtl_sm, rtsync, SM_ALLOC, tx);
2074 	range_tree_vacate(rtsync, NULL, NULL);
2075 
2076 	range_tree_destroy(rtsync);
2077 
2078 	mutex_exit(&rtlock);
2079 	mutex_destroy(&rtlock);
2080 
2081 	/*
2082 	 * If the object for the space map has changed then dirty
2083 	 * the top level so that we update the config.
2084 	 */
2085 	if (object != space_map_object(vd->vdev_dtl_sm)) {
2086 		zfs_dbgmsg("txg %llu, spa %s, DTL old object %llu, "
2087 		    "new object %llu", txg, spa_name(spa), object,
2088 		    space_map_object(vd->vdev_dtl_sm));
2089 		vdev_config_dirty(vd->vdev_top);
2090 	}
2091 
2092 	dmu_tx_commit(tx);
2093 
2094 	mutex_enter(&vd->vdev_dtl_lock);
2095 	space_map_update(vd->vdev_dtl_sm);
2096 	mutex_exit(&vd->vdev_dtl_lock);
2097 }
2098 
2099 /*
2100  * Determine whether the specified vdev can be offlined/detached/removed
2101  * without losing data.
2102  */
2103 boolean_t
2104 vdev_dtl_required(vdev_t *vd)
2105 {
2106 	spa_t *spa = vd->vdev_spa;
2107 	vdev_t *tvd = vd->vdev_top;
2108 	uint8_t cant_read = vd->vdev_cant_read;
2109 	boolean_t required;
2110 
2111 	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
2112 
2113 	if (vd == spa->spa_root_vdev || vd == tvd)
2114 		return (B_TRUE);
2115 
2116 	/*
2117 	 * Temporarily mark the device as unreadable, and then determine
2118 	 * whether this results in any DTL outages in the top-level vdev.
2119 	 * If not, we can safely offline/detach/remove the device.
2120 	 */
2121 	vd->vdev_cant_read = B_TRUE;
2122 	vdev_dtl_reassess(tvd, 0, 0, B_FALSE);
2123 	required = !vdev_dtl_empty(tvd, DTL_OUTAGE);
2124 	vd->vdev_cant_read = cant_read;
2125 	vdev_dtl_reassess(tvd, 0, 0, B_FALSE);
2126 
2127 	if (!required && zio_injection_enabled)
2128 		required = !!zio_handle_device_injection(vd, NULL, ECHILD);
2129 
2130 	return (required);
2131 }
2132 
2133 /*
2134  * Determine if resilver is needed, and if so the txg range.
2135  */
2136 boolean_t
2137 vdev_resilver_needed(vdev_t *vd, uint64_t *minp, uint64_t *maxp)
2138 {
2139 	boolean_t needed = B_FALSE;
2140 	uint64_t thismin = UINT64_MAX;
2141 	uint64_t thismax = 0;
2142 
2143 	if (vd->vdev_children == 0) {
2144 		mutex_enter(&vd->vdev_dtl_lock);
2145 		if (range_tree_space(vd->vdev_dtl[DTL_MISSING]) != 0 &&
2146 		    vdev_writeable(vd)) {
2147 
2148 			thismin = vdev_dtl_min(vd);
2149 			thismax = vdev_dtl_max(vd);
2150 			needed = B_TRUE;
2151 		}
2152 		mutex_exit(&vd->vdev_dtl_lock);
2153 	} else {
2154 		for (int c = 0; c < vd->vdev_children; c++) {
2155 			vdev_t *cvd = vd->vdev_child[c];
2156 			uint64_t cmin, cmax;
2157 
2158 			if (vdev_resilver_needed(cvd, &cmin, &cmax)) {
2159 				thismin = MIN(thismin, cmin);
2160 				thismax = MAX(thismax, cmax);
2161 				needed = B_TRUE;
2162 			}
2163 		}
2164 	}
2165 
2166 	if (needed && minp) {
2167 		*minp = thismin;
2168 		*maxp = thismax;
2169 	}
2170 	return (needed);
2171 }
2172 
2173 void
2174 vdev_load(vdev_t *vd)
2175 {
2176 	/*
2177 	 * Recursively load all children.
2178 	 */
2179 	for (int c = 0; c < vd->vdev_children; c++)
2180 		vdev_load(vd->vdev_child[c]);
2181 
2182 	/*
2183 	 * If this is a top-level vdev, initialize its metaslabs.
2184 	 */
2185 	if (vd == vd->vdev_top && !vd->vdev_ishole &&
2186 	    (vd->vdev_ashift == 0 || vd->vdev_asize == 0 ||
2187 	    vdev_metaslab_init(vd, 0) != 0))
2188 		vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
2189 		    VDEV_AUX_CORRUPT_DATA);
2190 
2191 	/*
2192 	 * If this is a leaf vdev, load its DTL.
2193 	 */
2194 	if (vd->vdev_ops->vdev_op_leaf && vdev_dtl_load(vd) != 0)
2195 		vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
2196 		    VDEV_AUX_CORRUPT_DATA);
2197 }
2198 
2199 /*
2200  * The special vdev case is used for hot spares and l2cache devices.  Its
2201  * sole purpose it to set the vdev state for the associated vdev.  To do this,
2202  * we make sure that we can open the underlying device, then try to read the
2203  * label, and make sure that the label is sane and that it hasn't been
2204  * repurposed to another pool.
2205  */
2206 int
2207 vdev_validate_aux(vdev_t *vd)
2208 {
2209 	nvlist_t *label;
2210 	uint64_t guid, version;
2211 	uint64_t state;
2212 
2213 	if (!vdev_readable(vd))
2214 		return (0);
2215 
2216 	if ((label = vdev_label_read_config(vd, -1ULL)) == NULL) {
2217 		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
2218 		    VDEV_AUX_CORRUPT_DATA);
2219 		return (-1);
2220 	}
2221 
2222 	if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_VERSION, &version) != 0 ||
2223 	    !SPA_VERSION_IS_SUPPORTED(version) ||
2224 	    nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID, &guid) != 0 ||
2225 	    guid != vd->vdev_guid ||
2226 	    nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE, &state) != 0) {
2227 		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
2228 		    VDEV_AUX_CORRUPT_DATA);
2229 		nvlist_free(label);
2230 		return (-1);
2231 	}
2232 
2233 	/*
2234 	 * We don't actually check the pool state here.  If it's in fact in
2235 	 * use by another pool, we update this fact on the fly when requested.
2236 	 */
2237 	nvlist_free(label);
2238 	return (0);
2239 }
2240 
2241 void
2242 vdev_remove(vdev_t *vd, uint64_t txg)
2243 {
2244 	spa_t *spa = vd->vdev_spa;
2245 	objset_t *mos = spa->spa_meta_objset;
2246 	dmu_tx_t *tx;
2247 
2248 	tx = dmu_tx_create_assigned(spa_get_dsl(spa), txg);
2249 	ASSERT(vd == vd->vdev_top);
2250 	ASSERT3U(txg, ==, spa_syncing_txg(spa));
2251 
2252 	if (vd->vdev_ms != NULL) {
2253 		metaslab_group_t *mg = vd->vdev_mg;
2254 
2255 		metaslab_group_histogram_verify(mg);
2256 		metaslab_class_histogram_verify(mg->mg_class);
2257 
2258 		for (int m = 0; m < vd->vdev_ms_count; m++) {
2259 			metaslab_t *msp = vd->vdev_ms[m];
2260 
2261 			if (msp == NULL || msp->ms_sm == NULL)
2262 				continue;
2263 
2264 			mutex_enter(&msp->ms_lock);
2265 			/*
2266 			 * If the metaslab was not loaded when the vdev
2267 			 * was removed then the histogram accounting may
2268 			 * not be accurate. Update the histogram information
2269 			 * here so that we ensure that the metaslab group
2270 			 * and metaslab class are up-to-date.
2271 			 */
2272 			metaslab_group_histogram_remove(mg, msp);
2273 
2274 			VERIFY0(space_map_allocated(msp->ms_sm));
2275 			space_map_free(msp->ms_sm, tx);
2276 			space_map_close(msp->ms_sm);
2277 			msp->ms_sm = NULL;
2278 			mutex_exit(&msp->ms_lock);
2279 		}
2280 
2281 		metaslab_group_histogram_verify(mg);
2282 		metaslab_class_histogram_verify(mg->mg_class);
2283 		for (int i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i++)
2284 			ASSERT0(mg->mg_histogram[i]);
2285 
2286 	}
2287 
2288 	if (vd->vdev_ms_array) {
2289 		(void) dmu_object_free(mos, vd->vdev_ms_array, tx);
2290 		vd->vdev_ms_array = 0;
2291 	}
2292 
2293 	if (vd->vdev_islog && vd->vdev_top_zap != 0) {
2294 		vdev_destroy_unlink_zap(vd, vd->vdev_top_zap, tx);
2295 		vd->vdev_top_zap = 0;
2296 	}
2297 	dmu_tx_commit(tx);
2298 }
2299 
2300 void
2301 vdev_sync_done(vdev_t *vd, uint64_t txg)
2302 {
2303 	metaslab_t *msp;
2304 	boolean_t reassess = !txg_list_empty(&vd->vdev_ms_list, TXG_CLEAN(txg));
2305 
2306 	ASSERT(!vd->vdev_ishole);
2307 
2308 	while (msp = txg_list_remove(&vd->vdev_ms_list, TXG_CLEAN(txg)))
2309 		metaslab_sync_done(msp, txg);
2310 
2311 	if (reassess)
2312 		metaslab_sync_reassess(vd->vdev_mg);
2313 }
2314 
2315 void
2316 vdev_sync(vdev_t *vd, uint64_t txg)
2317 {
2318 	spa_t *spa = vd->vdev_spa;
2319 	vdev_t *lvd;
2320 	metaslab_t *msp;
2321 	dmu_tx_t *tx;
2322 
2323 	ASSERT(!vd->vdev_ishole);
2324 
2325 	if (vd->vdev_ms_array == 0 && vd->vdev_ms_shift != 0) {
2326 		ASSERT(vd == vd->vdev_top);
2327 		tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
2328 		vd->vdev_ms_array = dmu_object_alloc(spa->spa_meta_objset,
2329 		    DMU_OT_OBJECT_ARRAY, 0, DMU_OT_NONE, 0, tx);
2330 		ASSERT(vd->vdev_ms_array != 0);
2331 		vdev_config_dirty(vd);
2332 		dmu_tx_commit(tx);
2333 	}
2334 
2335 	/*
2336 	 * Remove the metadata associated with this vdev once it's empty.
2337 	 */
2338 	if (vd->vdev_stat.vs_alloc == 0 && vd->vdev_removing)
2339 		vdev_remove(vd, txg);
2340 
2341 	while ((msp = txg_list_remove(&vd->vdev_ms_list, txg)) != NULL) {
2342 		metaslab_sync(msp, txg);
2343 		(void) txg_list_add(&vd->vdev_ms_list, msp, TXG_CLEAN(txg));
2344 	}
2345 
2346 	while ((lvd = txg_list_remove(&vd->vdev_dtl_list, txg)) != NULL)
2347 		vdev_dtl_sync(lvd, txg);
2348 
2349 	(void) txg_list_add(&spa->spa_vdev_txg_list, vd, TXG_CLEAN(txg));
2350 }
2351 
2352 uint64_t
2353 vdev_psize_to_asize(vdev_t *vd, uint64_t psize)
2354 {
2355 	return (vd->vdev_ops->vdev_op_asize(vd, psize));
2356 }
2357 
2358 /*
2359  * Mark the given vdev faulted.  A faulted vdev behaves as if the device could
2360  * not be opened, and no I/O is attempted.
2361  */
2362 int
2363 vdev_fault(spa_t *spa, uint64_t guid, vdev_aux_t aux)
2364 {
2365 	vdev_t *vd, *tvd;
2366 
2367 	spa_vdev_state_enter(spa, SCL_NONE);
2368 
2369 	if ((vd = spa_lookup_by_guid(spa, guid, B_TRUE)) == NULL)
2370 		return (spa_vdev_state_exit(spa, NULL, ENODEV));
2371 
2372 	if (!vd->vdev_ops->vdev_op_leaf)
2373 		return (spa_vdev_state_exit(spa, NULL, ENOTSUP));
2374 
2375 	tvd = vd->vdev_top;
2376 
2377 	/*
2378 	 * We don't directly use the aux state here, but if we do a
2379 	 * vdev_reopen(), we need this value to be present to remember why we
2380 	 * were faulted.
2381 	 */
2382 	vd->vdev_label_aux = aux;
2383 
2384 	/*
2385 	 * Faulted state takes precedence over degraded.
2386 	 */
2387 	vd->vdev_delayed_close = B_FALSE;
2388 	vd->vdev_faulted = 1ULL;
2389 	vd->vdev_degraded = 0ULL;
2390 	vdev_set_state(vd, B_FALSE, VDEV_STATE_FAULTED, aux);
2391 
2392 	/*
2393 	 * If this device has the only valid copy of the data, then
2394 	 * back off and simply mark the vdev as degraded instead.
2395 	 */
2396 	if (!tvd->vdev_islog && vd->vdev_aux == NULL && vdev_dtl_required(vd)) {
2397 		vd->vdev_degraded = 1ULL;
2398 		vd->vdev_faulted = 0ULL;
2399 
2400 		/*
2401 		 * If we reopen the device and it's not dead, only then do we
2402 		 * mark it degraded.
2403 		 */
2404 		vdev_reopen(tvd);
2405 
2406 		if (vdev_readable(vd))
2407 			vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, aux);
2408 	}
2409 
2410 	return (spa_vdev_state_exit(spa, vd, 0));
2411 }
2412 
2413 /*
2414  * Mark the given vdev degraded.  A degraded vdev is purely an indication to the
2415  * user that something is wrong.  The vdev continues to operate as normal as far
2416  * as I/O is concerned.
2417  */
2418 int
2419 vdev_degrade(spa_t *spa, uint64_t guid, vdev_aux_t aux)
2420 {
2421 	vdev_t *vd;
2422 
2423 	spa_vdev_state_enter(spa, SCL_NONE);
2424 
2425 	if ((vd = spa_lookup_by_guid(spa, guid, B_TRUE)) == NULL)
2426 		return (spa_vdev_state_exit(spa, NULL, ENODEV));
2427 
2428 	if (!vd->vdev_ops->vdev_op_leaf)
2429 		return (spa_vdev_state_exit(spa, NULL, ENOTSUP));
2430 
2431 	/*
2432 	 * If the vdev is already faulted, then don't do anything.
2433 	 */
2434 	if (vd->vdev_faulted || vd->vdev_degraded)
2435 		return (spa_vdev_state_exit(spa, NULL, 0));
2436 
2437 	vd->vdev_degraded = 1ULL;
2438 	if (!vdev_is_dead(vd))
2439 		vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED,
2440 		    aux);
2441 
2442 	return (spa_vdev_state_exit(spa, vd, 0));
2443 }
2444 
2445 /*
2446  * Online the given vdev.
2447  *
2448  * If 'ZFS_ONLINE_UNSPARE' is set, it implies two things.  First, any attached
2449  * spare device should be detached when the device finishes resilvering.
2450  * Second, the online should be treated like a 'test' online case, so no FMA
2451  * events are generated if the device fails to open.
2452  */
2453 int
2454 vdev_online(spa_t *spa, uint64_t guid, uint64_t flags, vdev_state_t *newstate)
2455 {
2456 	vdev_t *vd, *tvd, *pvd, *rvd = spa->spa_root_vdev;
2457 	boolean_t wasoffline;
2458 	vdev_state_t oldstate;
2459 
2460 	spa_vdev_state_enter(spa, SCL_NONE);
2461 
2462 	if ((vd = spa_lookup_by_guid(spa, guid, B_TRUE)) == NULL)
2463 		return (spa_vdev_state_exit(spa, NULL, ENODEV));
2464 
2465 	if (!vd->vdev_ops->vdev_op_leaf)
2466 		return (spa_vdev_state_exit(spa, NULL, ENOTSUP));
2467 
2468 	wasoffline = (vd->vdev_offline || vd->vdev_tmpoffline);
2469 	oldstate = vd->vdev_state;
2470 
2471 	tvd = vd->vdev_top;
2472 	vd->vdev_offline = B_FALSE;
2473 	vd->vdev_tmpoffline = B_FALSE;
2474 	vd->vdev_checkremove = !!(flags & ZFS_ONLINE_CHECKREMOVE);
2475 	vd->vdev_forcefault = !!(flags & ZFS_ONLINE_FORCEFAULT);
2476 
2477 	/* XXX - L2ARC 1.0 does not support expansion */
2478 	if (!vd->vdev_aux) {
2479 		for (pvd = vd; pvd != rvd; pvd = pvd->vdev_parent)
2480 			pvd->vdev_expanding = !!(flags & ZFS_ONLINE_EXPAND);
2481 	}
2482 
2483 	vdev_reopen(tvd);
2484 	vd->vdev_checkremove = vd->vdev_forcefault = B_FALSE;
2485 
2486 	if (!vd->vdev_aux) {
2487 		for (pvd = vd; pvd != rvd; pvd = pvd->vdev_parent)
2488 			pvd->vdev_expanding = B_FALSE;
2489 	}
2490 
2491 	if (newstate)
2492 		*newstate = vd->vdev_state;
2493 	if ((flags & ZFS_ONLINE_UNSPARE) &&
2494 	    !vdev_is_dead(vd) && vd->vdev_parent &&
2495 	    vd->vdev_parent->vdev_ops == &vdev_spare_ops &&
2496 	    vd->vdev_parent->vdev_child[0] == vd)
2497 		vd->vdev_unspare = B_TRUE;
2498 
2499 	if ((flags & ZFS_ONLINE_EXPAND) || spa->spa_autoexpand) {
2500 
2501 		/* XXX - L2ARC 1.0 does not support expansion */
2502 		if (vd->vdev_aux)
2503 			return (spa_vdev_state_exit(spa, vd, ENOTSUP));
2504 		spa_async_request(spa, SPA_ASYNC_CONFIG_UPDATE);
2505 	}
2506 
2507 	if (wasoffline ||
2508 	    (oldstate < VDEV_STATE_DEGRADED &&
2509 	    vd->vdev_state >= VDEV_STATE_DEGRADED))
2510 		spa_event_notify(spa, vd, NULL, ESC_ZFS_VDEV_ONLINE);
2511 
2512 	return (spa_vdev_state_exit(spa, vd, 0));
2513 }
2514 
2515 static int
2516 vdev_offline_locked(spa_t *spa, uint64_t guid, uint64_t flags)
2517 {
2518 	vdev_t *vd, *tvd;
2519 	int error = 0;
2520 	uint64_t generation;
2521 	metaslab_group_t *mg;
2522 
2523 top:
2524 	spa_vdev_state_enter(spa, SCL_ALLOC);
2525 
2526 	if ((vd = spa_lookup_by_guid(spa, guid, B_TRUE)) == NULL)
2527 		return (spa_vdev_state_exit(spa, NULL, ENODEV));
2528 
2529 	if (!vd->vdev_ops->vdev_op_leaf)
2530 		return (spa_vdev_state_exit(spa, NULL, ENOTSUP));
2531 
2532 	tvd = vd->vdev_top;
2533 	mg = tvd->vdev_mg;
2534 	generation = spa->spa_config_generation + 1;
2535 
2536 	/*
2537 	 * If the device isn't already offline, try to offline it.
2538 	 */
2539 	if (!vd->vdev_offline) {
2540 		/*
2541 		 * If this device has the only valid copy of some data,
2542 		 * don't allow it to be offlined. Log devices are always
2543 		 * expendable.
2544 		 */
2545 		if (!tvd->vdev_islog && vd->vdev_aux == NULL &&
2546 		    vdev_dtl_required(vd))
2547 			return (spa_vdev_state_exit(spa, NULL, EBUSY));
2548 
2549 		/*
2550 		 * If the top-level is a slog and it has had allocations
2551 		 * then proceed.  We check that the vdev's metaslab group
2552 		 * is not NULL since it's possible that we may have just
2553 		 * added this vdev but not yet initialized its metaslabs.
2554 		 */
2555 		if (tvd->vdev_islog && mg != NULL) {
2556 			/*
2557 			 * Prevent any future allocations.
2558 			 */
2559 			metaslab_group_passivate(mg);
2560 			(void) spa_vdev_state_exit(spa, vd, 0);
2561 
2562 			error = spa_offline_log(spa);
2563 
2564 			spa_vdev_state_enter(spa, SCL_ALLOC);
2565 
2566 			/*
2567 			 * Check to see if the config has changed.
2568 			 */
2569 			if (error || generation != spa->spa_config_generation) {
2570 				metaslab_group_activate(mg);
2571 				if (error)
2572 					return (spa_vdev_state_exit(spa,
2573 					    vd, error));
2574 				(void) spa_vdev_state_exit(spa, vd, 0);
2575 				goto top;
2576 			}
2577 			ASSERT0(tvd->vdev_stat.vs_alloc);
2578 		}
2579 
2580 		/*
2581 		 * Offline this device and reopen its top-level vdev.
2582 		 * If the top-level vdev is a log device then just offline
2583 		 * it. Otherwise, if this action results in the top-level
2584 		 * vdev becoming unusable, undo it and fail the request.
2585 		 */
2586 		vd->vdev_offline = B_TRUE;
2587 		vdev_reopen(tvd);
2588 
2589 		if (!tvd->vdev_islog && vd->vdev_aux == NULL &&
2590 		    vdev_is_dead(tvd)) {
2591 			vd->vdev_offline = B_FALSE;
2592 			vdev_reopen(tvd);
2593 			return (spa_vdev_state_exit(spa, NULL, EBUSY));
2594 		}
2595 
2596 		/*
2597 		 * Add the device back into the metaslab rotor so that
2598 		 * once we online the device it's open for business.
2599 		 */
2600 		if (tvd->vdev_islog && mg != NULL)
2601 			metaslab_group_activate(mg);
2602 	}
2603 
2604 	vd->vdev_tmpoffline = !!(flags & ZFS_OFFLINE_TEMPORARY);
2605 
2606 	return (spa_vdev_state_exit(spa, vd, 0));
2607 }
2608 
2609 int
2610 vdev_offline(spa_t *spa, uint64_t guid, uint64_t flags)
2611 {
2612 	int error;
2613 
2614 	mutex_enter(&spa->spa_vdev_top_lock);
2615 	error = vdev_offline_locked(spa, guid, flags);
2616 	mutex_exit(&spa->spa_vdev_top_lock);
2617 
2618 	return (error);
2619 }
2620 
2621 /*
2622  * Clear the error counts associated with this vdev.  Unlike vdev_online() and
2623  * vdev_offline(), we assume the spa config is locked.  We also clear all
2624  * children.  If 'vd' is NULL, then the user wants to clear all vdevs.
2625  */
2626 void
2627 vdev_clear(spa_t *spa, vdev_t *vd)
2628 {
2629 	vdev_t *rvd = spa->spa_root_vdev;
2630 
2631 	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
2632 
2633 	if (vd == NULL)
2634 		vd = rvd;
2635 
2636 	vd->vdev_stat.vs_read_errors = 0;
2637 	vd->vdev_stat.vs_write_errors = 0;
2638 	vd->vdev_stat.vs_checksum_errors = 0;
2639 
2640 	for (int c = 0; c < vd->vdev_children; c++)
2641 		vdev_clear(spa, vd->vdev_child[c]);
2642 
2643 	/*
2644 	 * If we're in the FAULTED state or have experienced failed I/O, then
2645 	 * clear the persistent state and attempt to reopen the device.  We
2646 	 * also mark the vdev config dirty, so that the new faulted state is
2647 	 * written out to disk.
2648 	 */
2649 	if (vd->vdev_faulted || vd->vdev_degraded ||
2650 	    !vdev_readable(vd) || !vdev_writeable(vd)) {
2651 
2652 		/*
2653 		 * When reopening in reponse to a clear event, it may be due to
2654 		 * a fmadm repair request.  In this case, if the device is
2655 		 * still broken, we want to still post the ereport again.
2656 		 */
2657 		vd->vdev_forcefault = B_TRUE;
2658 
2659 		vd->vdev_faulted = vd->vdev_degraded = 0ULL;
2660 		vd->vdev_cant_read = B_FALSE;
2661 		vd->vdev_cant_write = B_FALSE;
2662 
2663 		vdev_reopen(vd == rvd ? rvd : vd->vdev_top);
2664 
2665 		vd->vdev_forcefault = B_FALSE;
2666 
2667 		if (vd != rvd && vdev_writeable(vd->vdev_top))
2668 			vdev_state_dirty(vd->vdev_top);
2669 
2670 		if (vd->vdev_aux == NULL && !vdev_is_dead(vd))
2671 			spa_async_request(spa, SPA_ASYNC_RESILVER);
2672 
2673 		spa_event_notify(spa, vd, NULL, ESC_ZFS_VDEV_CLEAR);
2674 	}
2675 
2676 	/*
2677 	 * When clearing a FMA-diagnosed fault, we always want to
2678 	 * unspare the device, as we assume that the original spare was
2679 	 * done in response to the FMA fault.
2680 	 */
2681 	if (!vdev_is_dead(vd) && vd->vdev_parent != NULL &&
2682 	    vd->vdev_parent->vdev_ops == &vdev_spare_ops &&
2683 	    vd->vdev_parent->vdev_child[0] == vd)
2684 		vd->vdev_unspare = B_TRUE;
2685 }
2686 
2687 boolean_t
2688 vdev_is_dead(vdev_t *vd)
2689 {
2690 	/*
2691 	 * Holes and missing devices are always considered "dead".
2692 	 * This simplifies the code since we don't have to check for
2693 	 * these types of devices in the various code paths.
2694 	 * Instead we rely on the fact that we skip over dead devices
2695 	 * before issuing I/O to them.
2696 	 */
2697 	return (vd->vdev_state < VDEV_STATE_DEGRADED || vd->vdev_ishole ||
2698 	    vd->vdev_ops == &vdev_missing_ops);
2699 }
2700 
2701 boolean_t
2702 vdev_readable(vdev_t *vd)
2703 {
2704 	return (!vdev_is_dead(vd) && !vd->vdev_cant_read);
2705 }
2706 
2707 boolean_t
2708 vdev_writeable(vdev_t *vd)
2709 {
2710 	return (!vdev_is_dead(vd) && !vd->vdev_cant_write);
2711 }
2712 
2713 boolean_t
2714 vdev_allocatable(vdev_t *vd)
2715 {
2716 	uint64_t state = vd->vdev_state;
2717 
2718 	/*
2719 	 * We currently allow allocations from vdevs which may be in the
2720 	 * process of reopening (i.e. VDEV_STATE_CLOSED). If the device
2721 	 * fails to reopen then we'll catch it later when we're holding
2722 	 * the proper locks.  Note that we have to get the vdev state
2723 	 * in a local variable because although it changes atomically,
2724 	 * we're asking two separate questions about it.
2725 	 */
2726 	return (!(state < VDEV_STATE_DEGRADED && state != VDEV_STATE_CLOSED) &&
2727 	    !vd->vdev_cant_write && !vd->vdev_ishole &&
2728 	    vd->vdev_mg->mg_initialized);
2729 }
2730 
2731 boolean_t
2732 vdev_accessible(vdev_t *vd, zio_t *zio)
2733 {
2734 	ASSERT(zio->io_vd == vd);
2735 
2736 	if (vdev_is_dead(vd) || vd->vdev_remove_wanted)
2737 		return (B_FALSE);
2738 
2739 	if (zio->io_type == ZIO_TYPE_READ)
2740 		return (!vd->vdev_cant_read);
2741 
2742 	if (zio->io_type == ZIO_TYPE_WRITE)
2743 		return (!vd->vdev_cant_write);
2744 
2745 	return (B_TRUE);
2746 }
2747 
2748 /*
2749  * Get statistics for the given vdev.
2750  */
2751 void
2752 vdev_get_stats(vdev_t *vd, vdev_stat_t *vs)
2753 {
2754 	spa_t *spa = vd->vdev_spa;
2755 	vdev_t *rvd = spa->spa_root_vdev;
2756 	vdev_t *tvd = vd->vdev_top;
2757 
2758 	ASSERT(spa_config_held(spa, SCL_ALL, RW_READER) != 0);
2759 
2760 	mutex_enter(&vd->vdev_stat_lock);
2761 	bcopy(&vd->vdev_stat, vs, sizeof (*vs));
2762 	vs->vs_timestamp = gethrtime() - vs->vs_timestamp;
2763 	vs->vs_state = vd->vdev_state;
2764 	vs->vs_rsize = vdev_get_min_asize(vd);
2765 	if (vd->vdev_ops->vdev_op_leaf)
2766 		vs->vs_rsize += VDEV_LABEL_START_SIZE + VDEV_LABEL_END_SIZE;
2767 	/*
2768 	 * Report expandable space on top-level, non-auxillary devices only.
2769 	 * The expandable space is reported in terms of metaslab sized units
2770 	 * since that determines how much space the pool can expand.
2771 	 */
2772 	if (vd->vdev_aux == NULL && tvd != NULL) {
2773 		vs->vs_esize = P2ALIGN(vd->vdev_max_asize - vd->vdev_asize -
2774 		    spa->spa_bootsize, 1ULL << tvd->vdev_ms_shift);
2775 	}
2776 	if (vd->vdev_aux == NULL && vd == vd->vdev_top && !vd->vdev_ishole) {
2777 		vs->vs_fragmentation = vd->vdev_mg->mg_fragmentation;
2778 	}
2779 
2780 	/*
2781 	 * If we're getting stats on the root vdev, aggregate the I/O counts
2782 	 * over all top-level vdevs (i.e. the direct children of the root).
2783 	 */
2784 	if (vd == rvd) {
2785 		for (int c = 0; c < rvd->vdev_children; c++) {
2786 			vdev_t *cvd = rvd->vdev_child[c];
2787 			vdev_stat_t *cvs = &cvd->vdev_stat;
2788 
2789 			for (int t = 0; t < ZIO_TYPES; t++) {
2790 				vs->vs_ops[t] += cvs->vs_ops[t];
2791 				vs->vs_bytes[t] += cvs->vs_bytes[t];
2792 			}
2793 			cvs->vs_scan_removing = cvd->vdev_removing;
2794 		}
2795 	}
2796 	mutex_exit(&vd->vdev_stat_lock);
2797 }
2798 
2799 void
2800 vdev_clear_stats(vdev_t *vd)
2801 {
2802 	mutex_enter(&vd->vdev_stat_lock);
2803 	vd->vdev_stat.vs_space = 0;
2804 	vd->vdev_stat.vs_dspace = 0;
2805 	vd->vdev_stat.vs_alloc = 0;
2806 	mutex_exit(&vd->vdev_stat_lock);
2807 }
2808 
2809 void
2810 vdev_scan_stat_init(vdev_t *vd)
2811 {
2812 	vdev_stat_t *vs = &vd->vdev_stat;
2813 
2814 	for (int c = 0; c < vd->vdev_children; c++)
2815 		vdev_scan_stat_init(vd->vdev_child[c]);
2816 
2817 	mutex_enter(&vd->vdev_stat_lock);
2818 	vs->vs_scan_processed = 0;
2819 	mutex_exit(&vd->vdev_stat_lock);
2820 }
2821 
2822 void
2823 vdev_stat_update(zio_t *zio, uint64_t psize)
2824 {
2825 	spa_t *spa = zio->io_spa;
2826 	vdev_t *rvd = spa->spa_root_vdev;
2827 	vdev_t *vd = zio->io_vd ? zio->io_vd : rvd;
2828 	vdev_t *pvd;
2829 	uint64_t txg = zio->io_txg;
2830 	vdev_stat_t *vs = &vd->vdev_stat;
2831 	zio_type_t type = zio->io_type;
2832 	int flags = zio->io_flags;
2833 
2834 	/*
2835 	 * If this i/o is a gang leader, it didn't do any actual work.
2836 	 */
2837 	if (zio->io_gang_tree)
2838 		return;
2839 
2840 	if (zio->io_error == 0) {
2841 		/*
2842 		 * If this is a root i/o, don't count it -- we've already
2843 		 * counted the top-level vdevs, and vdev_get_stats() will
2844 		 * aggregate them when asked.  This reduces contention on
2845 		 * the root vdev_stat_lock and implicitly handles blocks
2846 		 * that compress away to holes, for which there is no i/o.
2847 		 * (Holes never create vdev children, so all the counters
2848 		 * remain zero, which is what we want.)
2849 		 *
2850 		 * Note: this only applies to successful i/o (io_error == 0)
2851 		 * because unlike i/o counts, errors are not additive.
2852 		 * When reading a ditto block, for example, failure of
2853 		 * one top-level vdev does not imply a root-level error.
2854 		 */
2855 		if (vd == rvd)
2856 			return;
2857 
2858 		ASSERT(vd == zio->io_vd);
2859 
2860 		if (flags & ZIO_FLAG_IO_BYPASS)
2861 			return;
2862 
2863 		mutex_enter(&vd->vdev_stat_lock);
2864 
2865 		if (flags & ZIO_FLAG_IO_REPAIR) {
2866 			if (flags & ZIO_FLAG_SCAN_THREAD) {
2867 				dsl_scan_phys_t *scn_phys =
2868 				    &spa->spa_dsl_pool->dp_scan->scn_phys;
2869 				uint64_t *processed = &scn_phys->scn_processed;
2870 
2871 				/* XXX cleanup? */
2872 				if (vd->vdev_ops->vdev_op_leaf)
2873 					atomic_add_64(processed, psize);
2874 				vs->vs_scan_processed += psize;
2875 			}
2876 
2877 			if (flags & ZIO_FLAG_SELF_HEAL)
2878 				vs->vs_self_healed += psize;
2879 		}
2880 
2881 		vs->vs_ops[type]++;
2882 		vs->vs_bytes[type] += psize;
2883 
2884 		mutex_exit(&vd->vdev_stat_lock);
2885 		return;
2886 	}
2887 
2888 	if (flags & ZIO_FLAG_SPECULATIVE)
2889 		return;
2890 
2891 	/*
2892 	 * If this is an I/O error that is going to be retried, then ignore the
2893 	 * error.  Otherwise, the user may interpret B_FAILFAST I/O errors as
2894 	 * hard errors, when in reality they can happen for any number of
2895 	 * innocuous reasons (bus resets, MPxIO link failure, etc).
2896 	 */
2897 	if (zio->io_error == EIO &&
2898 	    !(zio->io_flags & ZIO_FLAG_IO_RETRY))
2899 		return;
2900 
2901 	/*
2902 	 * Intent logs writes won't propagate their error to the root
2903 	 * I/O so don't mark these types of failures as pool-level
2904 	 * errors.
2905 	 */
2906 	if (zio->io_vd == NULL && (zio->io_flags & ZIO_FLAG_DONT_PROPAGATE))
2907 		return;
2908 
2909 	mutex_enter(&vd->vdev_stat_lock);
2910 	if (type == ZIO_TYPE_READ && !vdev_is_dead(vd)) {
2911 		if (zio->io_error == ECKSUM)
2912 			vs->vs_checksum_errors++;
2913 		else
2914 			vs->vs_read_errors++;
2915 	}
2916 	if (type == ZIO_TYPE_WRITE && !vdev_is_dead(vd))
2917 		vs->vs_write_errors++;
2918 	mutex_exit(&vd->vdev_stat_lock);
2919 
2920 	if (type == ZIO_TYPE_WRITE && txg != 0 &&
2921 	    (!(flags & ZIO_FLAG_IO_REPAIR) ||
2922 	    (flags & ZIO_FLAG_SCAN_THREAD) ||
2923 	    spa->spa_claiming)) {
2924 		/*
2925 		 * This is either a normal write (not a repair), or it's
2926 		 * a repair induced by the scrub thread, or it's a repair
2927 		 * made by zil_claim() during spa_load() in the first txg.
2928 		 * In the normal case, we commit the DTL change in the same
2929 		 * txg as the block was born.  In the scrub-induced repair
2930 		 * case, we know that scrubs run in first-pass syncing context,
2931 		 * so we commit the DTL change in spa_syncing_txg(spa).
2932 		 * In the zil_claim() case, we commit in spa_first_txg(spa).
2933 		 *
2934 		 * We currently do not make DTL entries for failed spontaneous
2935 		 * self-healing writes triggered by normal (non-scrubbing)
2936 		 * reads, because we have no transactional context in which to
2937 		 * do so -- and it's not clear that it'd be desirable anyway.
2938 		 */
2939 		if (vd->vdev_ops->vdev_op_leaf) {
2940 			uint64_t commit_txg = txg;
2941 			if (flags & ZIO_FLAG_SCAN_THREAD) {
2942 				ASSERT(flags & ZIO_FLAG_IO_REPAIR);
2943 				ASSERT(spa_sync_pass(spa) == 1);
2944 				vdev_dtl_dirty(vd, DTL_SCRUB, txg, 1);
2945 				commit_txg = spa_syncing_txg(spa);
2946 			} else if (spa->spa_claiming) {
2947 				ASSERT(flags & ZIO_FLAG_IO_REPAIR);
2948 				commit_txg = spa_first_txg(spa);
2949 			}
2950 			ASSERT(commit_txg >= spa_syncing_txg(spa));
2951 			if (vdev_dtl_contains(vd, DTL_MISSING, txg, 1))
2952 				return;
2953 			for (pvd = vd; pvd != rvd; pvd = pvd->vdev_parent)
2954 				vdev_dtl_dirty(pvd, DTL_PARTIAL, txg, 1);
2955 			vdev_dirty(vd->vdev_top, VDD_DTL, vd, commit_txg);
2956 		}
2957 		if (vd != rvd)
2958 			vdev_dtl_dirty(vd, DTL_MISSING, txg, 1);
2959 	}
2960 }
2961 
2962 /*
2963  * Update the in-core space usage stats for this vdev, its metaslab class,
2964  * and the root vdev.
2965  */
2966 void
2967 vdev_space_update(vdev_t *vd, int64_t alloc_delta, int64_t defer_delta,
2968     int64_t space_delta)
2969 {
2970 	int64_t dspace_delta = space_delta;
2971 	spa_t *spa = vd->vdev_spa;
2972 	vdev_t *rvd = spa->spa_root_vdev;
2973 	metaslab_group_t *mg = vd->vdev_mg;
2974 	metaslab_class_t *mc = mg ? mg->mg_class : NULL;
2975 
2976 	ASSERT(vd == vd->vdev_top);
2977 
2978 	/*
2979 	 * Apply the inverse of the psize-to-asize (ie. RAID-Z) space-expansion
2980 	 * factor.  We must calculate this here and not at the root vdev
2981 	 * because the root vdev's psize-to-asize is simply the max of its
2982 	 * childrens', thus not accurate enough for us.
2983 	 */
2984 	ASSERT((dspace_delta & (SPA_MINBLOCKSIZE-1)) == 0);
2985 	ASSERT(vd->vdev_deflate_ratio != 0 || vd->vdev_isl2cache);
2986 	dspace_delta = (dspace_delta >> SPA_MINBLOCKSHIFT) *
2987 	    vd->vdev_deflate_ratio;
2988 
2989 	mutex_enter(&vd->vdev_stat_lock);
2990 	vd->vdev_stat.vs_alloc += alloc_delta;
2991 	vd->vdev_stat.vs_space += space_delta;
2992 	vd->vdev_stat.vs_dspace += dspace_delta;
2993 	mutex_exit(&vd->vdev_stat_lock);
2994 
2995 	if (mc == spa_normal_class(spa)) {
2996 		mutex_enter(&rvd->vdev_stat_lock);
2997 		rvd->vdev_stat.vs_alloc += alloc_delta;
2998 		rvd->vdev_stat.vs_space += space_delta;
2999 		rvd->vdev_stat.vs_dspace += dspace_delta;
3000 		mutex_exit(&rvd->vdev_stat_lock);
3001 	}
3002 
3003 	if (mc != NULL) {
3004 		ASSERT(rvd == vd->vdev_parent);
3005 		ASSERT(vd->vdev_ms_count != 0);
3006 
3007 		metaslab_class_space_update(mc,
3008 		    alloc_delta, defer_delta, space_delta, dspace_delta);
3009 	}
3010 }
3011 
3012 /*
3013  * Mark a top-level vdev's config as dirty, placing it on the dirty list
3014  * so that it will be written out next time the vdev configuration is synced.
3015  * If the root vdev is specified (vdev_top == NULL), dirty all top-level vdevs.
3016  */
3017 void
3018 vdev_config_dirty(vdev_t *vd)
3019 {
3020 	spa_t *spa = vd->vdev_spa;
3021 	vdev_t *rvd = spa->spa_root_vdev;
3022 	int c;
3023 
3024 	ASSERT(spa_writeable(spa));
3025 
3026 	/*
3027 	 * If this is an aux vdev (as with l2cache and spare devices), then we
3028 	 * update the vdev config manually and set the sync flag.
3029 	 */
3030 	if (vd->vdev_aux != NULL) {
3031 		spa_aux_vdev_t *sav = vd->vdev_aux;
3032 		nvlist_t **aux;
3033 		uint_t naux;
3034 
3035 		for (c = 0; c < sav->sav_count; c++) {
3036 			if (sav->sav_vdevs[c] == vd)
3037 				break;
3038 		}
3039 
3040 		if (c == sav->sav_count) {
3041 			/*
3042 			 * We're being removed.  There's nothing more to do.
3043 			 */
3044 			ASSERT(sav->sav_sync == B_TRUE);
3045 			return;
3046 		}
3047 
3048 		sav->sav_sync = B_TRUE;
3049 
3050 		if (nvlist_lookup_nvlist_array(sav->sav_config,
3051 		    ZPOOL_CONFIG_L2CACHE, &aux, &naux) != 0) {
3052 			VERIFY(nvlist_lookup_nvlist_array(sav->sav_config,
3053 			    ZPOOL_CONFIG_SPARES, &aux, &naux) == 0);
3054 		}
3055 
3056 		ASSERT(c < naux);
3057 
3058 		/*
3059 		 * Setting the nvlist in the middle if the array is a little
3060 		 * sketchy, but it will work.
3061 		 */
3062 		nvlist_free(aux[c]);
3063 		aux[c] = vdev_config_generate(spa, vd, B_TRUE, 0);
3064 
3065 		return;
3066 	}
3067 
3068 	/*
3069 	 * The dirty list is protected by the SCL_CONFIG lock.  The caller
3070 	 * must either hold SCL_CONFIG as writer, or must be the sync thread
3071 	 * (which holds SCL_CONFIG as reader).  There's only one sync thread,
3072 	 * so this is sufficient to ensure mutual exclusion.
3073 	 */
3074 	ASSERT(spa_config_held(spa, SCL_CONFIG, RW_WRITER) ||
3075 	    (dsl_pool_sync_context(spa_get_dsl(spa)) &&
3076 	    spa_config_held(spa, SCL_CONFIG, RW_READER)));
3077 
3078 	if (vd == rvd) {
3079 		for (c = 0; c < rvd->vdev_children; c++)
3080 			vdev_config_dirty(rvd->vdev_child[c]);
3081 	} else {
3082 		ASSERT(vd == vd->vdev_top);
3083 
3084 		if (!list_link_active(&vd->vdev_config_dirty_node) &&
3085 		    !vd->vdev_ishole)
3086 			list_insert_head(&spa->spa_config_dirty_list, vd);
3087 	}
3088 }
3089 
3090 void
3091 vdev_config_clean(vdev_t *vd)
3092 {
3093 	spa_t *spa = vd->vdev_spa;
3094 
3095 	ASSERT(spa_config_held(spa, SCL_CONFIG, RW_WRITER) ||
3096 	    (dsl_pool_sync_context(spa_get_dsl(spa)) &&
3097 	    spa_config_held(spa, SCL_CONFIG, RW_READER)));
3098 
3099 	ASSERT(list_link_active(&vd->vdev_config_dirty_node));
3100 	list_remove(&spa->spa_config_dirty_list, vd);
3101 }
3102 
3103 /*
3104  * Mark a top-level vdev's state as dirty, so that the next pass of
3105  * spa_sync() can convert this into vdev_config_dirty().  We distinguish
3106  * the state changes from larger config changes because they require
3107  * much less locking, and are often needed for administrative actions.
3108  */
3109 void
3110 vdev_state_dirty(vdev_t *vd)
3111 {
3112 	spa_t *spa = vd->vdev_spa;
3113 
3114 	ASSERT(spa_writeable(spa));
3115 	ASSERT(vd == vd->vdev_top);
3116 
3117 	/*
3118 	 * The state list is protected by the SCL_STATE lock.  The caller
3119 	 * must either hold SCL_STATE as writer, or must be the sync thread
3120 	 * (which holds SCL_STATE as reader).  There's only one sync thread,
3121 	 * so this is sufficient to ensure mutual exclusion.
3122 	 */
3123 	ASSERT(spa_config_held(spa, SCL_STATE, RW_WRITER) ||
3124 	    (dsl_pool_sync_context(spa_get_dsl(spa)) &&
3125 	    spa_config_held(spa, SCL_STATE, RW_READER)));
3126 
3127 	if (!list_link_active(&vd->vdev_state_dirty_node) && !vd->vdev_ishole)
3128 		list_insert_head(&spa->spa_state_dirty_list, vd);
3129 }
3130 
3131 void
3132 vdev_state_clean(vdev_t *vd)
3133 {
3134 	spa_t *spa = vd->vdev_spa;
3135 
3136 	ASSERT(spa_config_held(spa, SCL_STATE, RW_WRITER) ||
3137 	    (dsl_pool_sync_context(spa_get_dsl(spa)) &&
3138 	    spa_config_held(spa, SCL_STATE, RW_READER)));
3139 
3140 	ASSERT(list_link_active(&vd->vdev_state_dirty_node));
3141 	list_remove(&spa->spa_state_dirty_list, vd);
3142 }
3143 
3144 /*
3145  * Propagate vdev state up from children to parent.
3146  */
3147 void
3148 vdev_propagate_state(vdev_t *vd)
3149 {
3150 	spa_t *spa = vd->vdev_spa;
3151 	vdev_t *rvd = spa->spa_root_vdev;
3152 	int degraded = 0, faulted = 0;
3153 	int corrupted = 0;
3154 	vdev_t *child;
3155 
3156 	if (vd->vdev_children > 0) {
3157 		for (int c = 0; c < vd->vdev_children; c++) {
3158 			child = vd->vdev_child[c];
3159 
3160 			/*
3161 			 * Don't factor holes into the decision.
3162 			 */
3163 			if (child->vdev_ishole)
3164 				continue;
3165 
3166 			if (!vdev_readable(child) ||
3167 			    (!vdev_writeable(child) && spa_writeable(spa))) {
3168 				/*
3169 				 * Root special: if there is a top-level log
3170 				 * device, treat the root vdev as if it were
3171 				 * degraded.
3172 				 */
3173 				if (child->vdev_islog && vd == rvd)
3174 					degraded++;
3175 				else
3176 					faulted++;
3177 			} else if (child->vdev_state <= VDEV_STATE_DEGRADED) {
3178 				degraded++;
3179 			}
3180 
3181 			if (child->vdev_stat.vs_aux == VDEV_AUX_CORRUPT_DATA)
3182 				corrupted++;
3183 		}
3184 
3185 		vd->vdev_ops->vdev_op_state_change(vd, faulted, degraded);
3186 
3187 		/*
3188 		 * Root special: if there is a top-level vdev that cannot be
3189 		 * opened due to corrupted metadata, then propagate the root
3190 		 * vdev's aux state as 'corrupt' rather than 'insufficient
3191 		 * replicas'.
3192 		 */
3193 		if (corrupted && vd == rvd &&
3194 		    rvd->vdev_state == VDEV_STATE_CANT_OPEN)
3195 			vdev_set_state(rvd, B_FALSE, VDEV_STATE_CANT_OPEN,
3196 			    VDEV_AUX_CORRUPT_DATA);
3197 	}
3198 
3199 	if (vd->vdev_parent)
3200 		vdev_propagate_state(vd->vdev_parent);
3201 }
3202 
3203 /*
3204  * Set a vdev's state.  If this is during an open, we don't update the parent
3205  * state, because we're in the process of opening children depth-first.
3206  * Otherwise, we propagate the change to the parent.
3207  *
3208  * If this routine places a device in a faulted state, an appropriate ereport is
3209  * generated.
3210  */
3211 void
3212 vdev_set_state(vdev_t *vd, boolean_t isopen, vdev_state_t state, vdev_aux_t aux)
3213 {
3214 	uint64_t save_state;
3215 	spa_t *spa = vd->vdev_spa;
3216 
3217 	if (state == vd->vdev_state) {
3218 		vd->vdev_stat.vs_aux = aux;
3219 		return;
3220 	}
3221 
3222 	save_state = vd->vdev_state;
3223 
3224 	vd->vdev_state = state;
3225 	vd->vdev_stat.vs_aux = aux;
3226 
3227 	/*
3228 	 * If we are setting the vdev state to anything but an open state, then
3229 	 * always close the underlying device unless the device has requested
3230 	 * a delayed close (i.e. we're about to remove or fault the device).
3231 	 * Otherwise, we keep accessible but invalid devices open forever.
3232 	 * We don't call vdev_close() itself, because that implies some extra
3233 	 * checks (offline, etc) that we don't want here.  This is limited to
3234 	 * leaf devices, because otherwise closing the device will affect other
3235 	 * children.
3236 	 */
3237 	if (!vd->vdev_delayed_close && vdev_is_dead(vd) &&
3238 	    vd->vdev_ops->vdev_op_leaf)
3239 		vd->vdev_ops->vdev_op_close(vd);
3240 
3241 	/*
3242 	 * If we have brought this vdev back into service, we need
3243 	 * to notify fmd so that it can gracefully repair any outstanding
3244 	 * cases due to a missing device.  We do this in all cases, even those
3245 	 * that probably don't correlate to a repaired fault.  This is sure to
3246 	 * catch all cases, and we let the zfs-retire agent sort it out.  If
3247 	 * this is a transient state it's OK, as the retire agent will
3248 	 * double-check the state of the vdev before repairing it.
3249 	 */
3250 	if (state == VDEV_STATE_HEALTHY && vd->vdev_ops->vdev_op_leaf &&
3251 	    vd->vdev_prevstate != state)
3252 		zfs_post_state_change(spa, vd);
3253 
3254 	if (vd->vdev_removed &&
3255 	    state == VDEV_STATE_CANT_OPEN &&
3256 	    (aux == VDEV_AUX_OPEN_FAILED || vd->vdev_checkremove)) {
3257 		/*
3258 		 * If the previous state is set to VDEV_STATE_REMOVED, then this
3259 		 * device was previously marked removed and someone attempted to
3260 		 * reopen it.  If this failed due to a nonexistent device, then
3261 		 * keep the device in the REMOVED state.  We also let this be if
3262 		 * it is one of our special test online cases, which is only
3263 		 * attempting to online the device and shouldn't generate an FMA
3264 		 * fault.
3265 		 */
3266 		vd->vdev_state = VDEV_STATE_REMOVED;
3267 		vd->vdev_stat.vs_aux = VDEV_AUX_NONE;
3268 	} else if (state == VDEV_STATE_REMOVED) {
3269 		vd->vdev_removed = B_TRUE;
3270 	} else if (state == VDEV_STATE_CANT_OPEN) {
3271 		/*
3272 		 * If we fail to open a vdev during an import or recovery, we
3273 		 * mark it as "not available", which signifies that it was
3274 		 * never there to begin with.  Failure to open such a device
3275 		 * is not considered an error.
3276 		 */
3277 		if ((spa_load_state(spa) == SPA_LOAD_IMPORT ||
3278 		    spa_load_state(spa) == SPA_LOAD_RECOVER) &&
3279 		    vd->vdev_ops->vdev_op_leaf)
3280 			vd->vdev_not_present = 1;
3281 
3282 		/*
3283 		 * Post the appropriate ereport.  If the 'prevstate' field is
3284 		 * set to something other than VDEV_STATE_UNKNOWN, it indicates
3285 		 * that this is part of a vdev_reopen().  In this case, we don't
3286 		 * want to post the ereport if the device was already in the
3287 		 * CANT_OPEN state beforehand.
3288 		 *
3289 		 * If the 'checkremove' flag is set, then this is an attempt to
3290 		 * online the device in response to an insertion event.  If we
3291 		 * hit this case, then we have detected an insertion event for a
3292 		 * faulted or offline device that wasn't in the removed state.
3293 		 * In this scenario, we don't post an ereport because we are
3294 		 * about to replace the device, or attempt an online with
3295 		 * vdev_forcefault, which will generate the fault for us.
3296 		 */
3297 		if ((vd->vdev_prevstate != state || vd->vdev_forcefault) &&
3298 		    !vd->vdev_not_present && !vd->vdev_checkremove &&
3299 		    vd != spa->spa_root_vdev) {
3300 			const char *class;
3301 
3302 			switch (aux) {
3303 			case VDEV_AUX_OPEN_FAILED:
3304 				class = FM_EREPORT_ZFS_DEVICE_OPEN_FAILED;
3305 				break;
3306 			case VDEV_AUX_CORRUPT_DATA:
3307 				class = FM_EREPORT_ZFS_DEVICE_CORRUPT_DATA;
3308 				break;
3309 			case VDEV_AUX_NO_REPLICAS:
3310 				class = FM_EREPORT_ZFS_DEVICE_NO_REPLICAS;
3311 				break;
3312 			case VDEV_AUX_BAD_GUID_SUM:
3313 				class = FM_EREPORT_ZFS_DEVICE_BAD_GUID_SUM;
3314 				break;
3315 			case VDEV_AUX_TOO_SMALL:
3316 				class = FM_EREPORT_ZFS_DEVICE_TOO_SMALL;
3317 				break;
3318 			case VDEV_AUX_BAD_LABEL:
3319 				class = FM_EREPORT_ZFS_DEVICE_BAD_LABEL;
3320 				break;
3321 			default:
3322 				class = FM_EREPORT_ZFS_DEVICE_UNKNOWN;
3323 			}
3324 
3325 			zfs_ereport_post(class, spa, vd, NULL, save_state, 0);
3326 		}
3327 
3328 		/* Erase any notion of persistent removed state */
3329 		vd->vdev_removed = B_FALSE;
3330 	} else {
3331 		vd->vdev_removed = B_FALSE;
3332 	}
3333 
3334 	if (!isopen && vd->vdev_parent)
3335 		vdev_propagate_state(vd->vdev_parent);
3336 }
3337 
3338 /*
3339  * Check the vdev configuration to ensure that it's capable of supporting
3340  * a root pool. We do not support partial configuration.
3341  * In addition, only a single top-level vdev is allowed.
3342  */
3343 boolean_t
3344 vdev_is_bootable(vdev_t *vd)
3345 {
3346 	if (!vd->vdev_ops->vdev_op_leaf) {
3347 		char *vdev_type = vd->vdev_ops->vdev_op_type;
3348 
3349 		if (strcmp(vdev_type, VDEV_TYPE_ROOT) == 0 &&
3350 		    vd->vdev_children > 1) {
3351 			return (B_FALSE);
3352 		} else if (strcmp(vdev_type, VDEV_TYPE_MISSING) == 0) {
3353 			return (B_FALSE);
3354 		}
3355 	}
3356 
3357 	for (int c = 0; c < vd->vdev_children; c++) {
3358 		if (!vdev_is_bootable(vd->vdev_child[c]))
3359 			return (B_FALSE);
3360 	}
3361 	return (B_TRUE);
3362 }
3363 
3364 /*
3365  * Load the state from the original vdev tree (ovd) which
3366  * we've retrieved from the MOS config object. If the original
3367  * vdev was offline or faulted then we transfer that state to the
3368  * device in the current vdev tree (nvd).
3369  */
3370 void
3371 vdev_load_log_state(vdev_t *nvd, vdev_t *ovd)
3372 {
3373 	spa_t *spa = nvd->vdev_spa;
3374 
3375 	ASSERT(nvd->vdev_top->vdev_islog);
3376 	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
3377 	ASSERT3U(nvd->vdev_guid, ==, ovd->vdev_guid);
3378 
3379 	for (int c = 0; c < nvd->vdev_children; c++)
3380 		vdev_load_log_state(nvd->vdev_child[c], ovd->vdev_child[c]);
3381 
3382 	if (nvd->vdev_ops->vdev_op_leaf) {
3383 		/*
3384 		 * Restore the persistent vdev state
3385 		 */
3386 		nvd->vdev_offline = ovd->vdev_offline;
3387 		nvd->vdev_faulted = ovd->vdev_faulted;
3388 		nvd->vdev_degraded = ovd->vdev_degraded;
3389 		nvd->vdev_removed = ovd->vdev_removed;
3390 	}
3391 }
3392 
3393 /*
3394  * Determine if a log device has valid content.  If the vdev was
3395  * removed or faulted in the MOS config then we know that
3396  * the content on the log device has already been written to the pool.
3397  */
3398 boolean_t
3399 vdev_log_state_valid(vdev_t *vd)
3400 {
3401 	if (vd->vdev_ops->vdev_op_leaf && !vd->vdev_faulted &&
3402 	    !vd->vdev_removed)
3403 		return (B_TRUE);
3404 
3405 	for (int c = 0; c < vd->vdev_children; c++)
3406 		if (vdev_log_state_valid(vd->vdev_child[c]))
3407 			return (B_TRUE);
3408 
3409 	return (B_FALSE);
3410 }
3411 
3412 /*
3413  * Expand a vdev if possible.
3414  */
3415 void
3416 vdev_expand(vdev_t *vd, uint64_t txg)
3417 {
3418 	ASSERT(vd->vdev_top == vd);
3419 	ASSERT(spa_config_held(vd->vdev_spa, SCL_ALL, RW_WRITER) == SCL_ALL);
3420 
3421 	if ((vd->vdev_asize >> vd->vdev_ms_shift) > vd->vdev_ms_count) {
3422 		VERIFY(vdev_metaslab_init(vd, txg) == 0);
3423 		vdev_config_dirty(vd);
3424 	}
3425 }
3426 
3427 /*
3428  * Split a vdev.
3429  */
3430 void
3431 vdev_split(vdev_t *vd)
3432 {
3433 	vdev_t *cvd, *pvd = vd->vdev_parent;
3434 
3435 	vdev_remove_child(pvd, vd);
3436 	vdev_compact_children(pvd);
3437 
3438 	cvd = pvd->vdev_child[0];
3439 	if (pvd->vdev_children == 1) {
3440 		vdev_remove_parent(cvd);
3441 		cvd->vdev_splitting = B_TRUE;
3442 	}
3443 	vdev_propagate_state(cvd);
3444 }
3445 
3446 void
3447 vdev_deadman(vdev_t *vd)
3448 {
3449 	for (int c = 0; c < vd->vdev_children; c++) {
3450 		vdev_t *cvd = vd->vdev_child[c];
3451 
3452 		vdev_deadman(cvd);
3453 	}
3454 
3455 	if (vd->vdev_ops->vdev_op_leaf) {
3456 		vdev_queue_t *vq = &vd->vdev_queue;
3457 
3458 		mutex_enter(&vq->vq_lock);
3459 		if (avl_numnodes(&vq->vq_active_tree) > 0) {
3460 			spa_t *spa = vd->vdev_spa;
3461 			zio_t *fio;
3462 			uint64_t delta;
3463 
3464 			/*
3465 			 * Look at the head of all the pending queues,
3466 			 * if any I/O has been outstanding for longer than
3467 			 * the spa_deadman_synctime we panic the system.
3468 			 */
3469 			fio = avl_first(&vq->vq_active_tree);
3470 			delta = gethrtime() - fio->io_timestamp;
3471 			if (delta > spa_deadman_synctime(spa)) {
3472 				zfs_dbgmsg("SLOW IO: zio timestamp %lluns, "
3473 				    "delta %lluns, last io %lluns",
3474 				    fio->io_timestamp, delta,
3475 				    vq->vq_io_complete_ts);
3476 				fm_panic("I/O to pool '%s' appears to be "
3477 				    "hung.", spa_name(spa));
3478 			}
3479 		}
3480 		mutex_exit(&vq->vq_lock);
3481 	}
3482 }
3483