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 * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
23 * Use is subject to license terms.
24 */
25
26/*
27 * Copyright (c) 2012, 2018 by Delphix. All rights reserved.
28 * Copyright 2019 Joyent, Inc.
29 */
30
31#include <sys/zfs_context.h>
32#include <sys/spa.h>
33#include <sys/spa_impl.h>
34#include <sys/dsl_pool.h>
35#include <sys/dsl_scan.h>
36#include <sys/vdev_impl.h>
37#include <sys/zio.h>
38#include <sys/abd.h>
39#include <sys/fs/zfs.h>
40
41/*
42 * Vdev mirror kstats
43 */
44static kstat_t *mirror_ksp = NULL;
45
46typedef struct mirror_stats {
47	kstat_named_t vdev_mirror_stat_rotating_linear;
48	kstat_named_t vdev_mirror_stat_rotating_offset;
49	kstat_named_t vdev_mirror_stat_rotating_seek;
50	kstat_named_t vdev_mirror_stat_non_rotating_linear;
51	kstat_named_t vdev_mirror_stat_non_rotating_seek;
52
53	kstat_named_t vdev_mirror_stat_preferred_found;
54	kstat_named_t vdev_mirror_stat_preferred_not_found;
55} mirror_stats_t;
56
57static mirror_stats_t mirror_stats = {
58	/* New I/O follows directly the last I/O */
59	{ "rotating_linear",			KSTAT_DATA_UINT64 },
60	/* New I/O is within zfs_vdev_mirror_rotating_seek_offset of the last */
61	{ "rotating_offset",			KSTAT_DATA_UINT64 },
62	/* New I/O requires random seek */
63	{ "rotating_seek",			KSTAT_DATA_UINT64 },
64	/* New I/O follows directly the last I/O  (nonrot) */
65	{ "non_rotating_linear",		KSTAT_DATA_UINT64 },
66	/* New I/O requires random seek (nonrot) */
67	{ "non_rotating_seek",			KSTAT_DATA_UINT64 },
68	/* Preferred child vdev found */
69	{ "preferred_found",			KSTAT_DATA_UINT64 },
70	/* Preferred child vdev not found or equal load  */
71	{ "preferred_not_found",		KSTAT_DATA_UINT64 },
72
73};
74
75#define	MIRROR_STAT(stat)		(mirror_stats.stat.value.ui64)
76#define	MIRROR_INCR(stat, val)		atomic_add_64(&MIRROR_STAT(stat), val)
77#define	MIRROR_BUMP(stat)		MIRROR_INCR(stat, 1)
78
79void
80vdev_mirror_stat_init(void)
81{
82	mirror_ksp = kstat_create("zfs", 0, "vdev_mirror_stats",
83	    "misc", KSTAT_TYPE_NAMED,
84	    sizeof (mirror_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL);
85	if (mirror_ksp != NULL) {
86		mirror_ksp->ks_data = &mirror_stats;
87		kstat_install(mirror_ksp);
88	}
89}
90
91void
92vdev_mirror_stat_fini(void)
93{
94	if (mirror_ksp != NULL) {
95		kstat_delete(mirror_ksp);
96		mirror_ksp = NULL;
97	}
98}
99
100/*
101 * Virtual device vector for mirroring.
102 */
103
104typedef struct mirror_child {
105	vdev_t		*mc_vd;
106	uint64_t	mc_offset;
107	int		mc_error;
108	int		mc_load;
109	uint8_t		mc_tried;
110	uint8_t		mc_skipped;
111	uint8_t		mc_speculative;
112} mirror_child_t;
113
114typedef struct mirror_map {
115	int		*mm_preferred;
116	int		mm_preferred_cnt;
117	int		mm_children;
118	int		mm_resilvering;
119	int		mm_root;
120	mirror_child_t	mm_child[];
121} mirror_map_t;
122
123int vdev_mirror_shift = 21;
124
125/*
126 * The load configuration settings below are tuned by default for
127 * the case where all devices are of the same rotational type.
128 *
129 * If there is a mixture of rotating and non-rotating media, setting
130 * zfs_vdev_mirror_non_rotating_seek_inc to 0 may well provide better results
131 * as it will direct more reads to the non-rotating vdevs which are more likely
132 * to have a higher performance.
133 */
134
135/* Rotating media load calculation configuration. */
136static int zfs_vdev_mirror_rotating_inc = 0;
137static int zfs_vdev_mirror_rotating_seek_inc = 5;
138static int zfs_vdev_mirror_rotating_seek_offset = 1 * 1024 * 1024;
139
140/* Non-rotating media load calculation configuration. */
141static int zfs_vdev_mirror_non_rotating_inc = 0;
142static int zfs_vdev_mirror_non_rotating_seek_inc = 1;
143
144static inline size_t
145vdev_mirror_map_size(int children)
146{
147	return (offsetof(mirror_map_t, mm_child[children]) +
148	    sizeof (int) * children);
149}
150
151static inline mirror_map_t *
152vdev_mirror_map_alloc(int children, boolean_t resilvering, boolean_t root)
153{
154	mirror_map_t *mm;
155
156	mm = kmem_zalloc(vdev_mirror_map_size(children), KM_SLEEP);
157	mm->mm_children = children;
158	mm->mm_resilvering = resilvering;
159	mm->mm_root = root;
160	mm->mm_preferred = (int *)((uintptr_t)mm +
161	    offsetof(mirror_map_t, mm_child[children]));
162
163	return (mm);
164}
165
166static void
167vdev_mirror_map_free(zio_t *zio)
168{
169	mirror_map_t *mm = zio->io_vsd;
170
171	kmem_free(mm, vdev_mirror_map_size(mm->mm_children));
172}
173
174static const zio_vsd_ops_t vdev_mirror_vsd_ops = {
175	.vsd_free = vdev_mirror_map_free,
176	.vsd_cksum_report = zio_vsd_default_cksum_report
177};
178
179static int
180vdev_mirror_load(mirror_map_t *mm, vdev_t *vd, uint64_t zio_offset)
181{
182	uint64_t last_offset;
183	int64_t offset_diff;
184	int load;
185
186	/* All DVAs have equal weight at the root. */
187	if (mm->mm_root)
188		return (INT_MAX);
189
190	/*
191	 * We don't return INT_MAX if the device is resilvering i.e.
192	 * vdev_resilver_txg != 0 as when tested performance was slightly
193	 * worse overall when resilvering with compared to without.
194	 */
195
196	/* Fix zio_offset for leaf vdevs */
197	if (vd->vdev_ops->vdev_op_leaf)
198		zio_offset += VDEV_LABEL_START_SIZE;
199
200	/* Standard load based on pending queue length. */
201	load = vdev_queue_length(vd);
202	last_offset = vdev_queue_last_offset(vd);
203
204	if (vd->vdev_nonrot) {
205		/* Non-rotating media. */
206		if (last_offset == zio_offset) {
207			MIRROR_BUMP(vdev_mirror_stat_non_rotating_linear);
208			return (load + zfs_vdev_mirror_non_rotating_inc);
209		}
210
211		/*
212		 * Apply a seek penalty even for non-rotating devices as
213		 * sequential I/O's can be aggregated into fewer operations on
214		 * the device, thus avoiding unnecessary per-command overhead
215		 * and boosting performance.
216		 */
217		MIRROR_BUMP(vdev_mirror_stat_non_rotating_seek);
218		return (load + zfs_vdev_mirror_non_rotating_seek_inc);
219	}
220
221	/* Rotating media I/O's which directly follow the last I/O. */
222	if (last_offset == zio_offset) {
223		MIRROR_BUMP(vdev_mirror_stat_rotating_linear);
224		return (load + zfs_vdev_mirror_rotating_inc);
225	}
226
227	/*
228	 * Apply half the seek increment to I/O's within seek offset
229	 * of the last I/O issued to this vdev as they should incur less
230	 * of a seek increment.
231	 */
232	offset_diff = (int64_t)(last_offset - zio_offset);
233	if (ABS(offset_diff) < zfs_vdev_mirror_rotating_seek_offset) {
234		MIRROR_BUMP(vdev_mirror_stat_rotating_offset);
235		return (load + (zfs_vdev_mirror_rotating_seek_inc / 2));
236	}
237
238	/* Apply the full seek increment to all other I/O's. */
239	MIRROR_BUMP(vdev_mirror_stat_rotating_seek);
240	return (load + zfs_vdev_mirror_rotating_seek_inc);
241}
242
243static mirror_map_t *
244vdev_mirror_map_init(zio_t *zio)
245{
246	mirror_map_t *mm = NULL;
247	mirror_child_t *mc;
248	vdev_t *vd = zio->io_vd;
249	int c;
250
251	if (vd == NULL) {
252		dva_t *dva = zio->io_bp->blk_dva;
253		spa_t *spa = zio->io_spa;
254		dsl_scan_t *scn = NULL;
255		dva_t dva_copy[SPA_DVAS_PER_BP];
256
257		if (spa->spa_dsl_pool != NULL) {
258			scn = spa->spa_dsl_pool->dp_scan;
259		}
260		/*
261		 * The sequential scrub code sorts and issues all DVAs
262		 * of a bp separately. Each of these IOs includes all
263		 * original DVA copies so that repairs can be performed
264		 * in the event of an error, but we only actually want
265		 * to check the first DVA since the others will be
266		 * checked by their respective sorted IOs. Only if we
267		 * hit an error will we try all DVAs upon retrying.
268		 *
269		 * Note: This check is safe even if the user switches
270		 * from a legacy scrub to a sequential one in the middle
271		 * of processing, since scn_is_sorted isn't updated until
272		 * all outstanding IOs from the previous scrub pass
273		 * complete.
274		 */
275		if ((zio->io_flags & ZIO_FLAG_SCRUB) &&
276		    !(zio->io_flags & ZIO_FLAG_IO_RETRY) &&
277		    scn != NULL &&
278		    scn->scn_is_sorted &&
279		    dsl_scan_scrubbing(spa->spa_dsl_pool)) {
280			c = 1;
281		} else {
282			c = BP_GET_NDVAS(zio->io_bp);
283		}
284
285		/*
286		 * If we do not trust the pool config, some DVAs might be
287		 * invalid or point to vdevs that do not exist. We skip them.
288		 */
289		if (!spa_trust_config(spa)) {
290			ASSERT3U(zio->io_type, ==, ZIO_TYPE_READ);
291			int j = 0;
292			for (int i = 0; i < c; i++) {
293				if (zfs_dva_valid(spa, &dva[i], zio->io_bp))
294					dva_copy[j++] = dva[i];
295			}
296			if (j == 0) {
297				zio->io_vsd = NULL;
298				zio->io_error = ENXIO;
299				return (NULL);
300			}
301			if (j < c) {
302				dva = dva_copy;
303				c = j;
304			}
305		}
306
307		mm = vdev_mirror_map_alloc(c, B_FALSE, B_TRUE);
308		for (c = 0; c < mm->mm_children; c++) {
309			mc = &mm->mm_child[c];
310
311			mc->mc_vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[c]));
312			mc->mc_offset = DVA_GET_OFFSET(&dva[c]);
313		}
314	} else {
315		/*
316		 * If we are resilvering, then we should handle scrub reads
317		 * differently; we shouldn't issue them to the resilvering
318		 * device because it might not have those blocks.
319		 *
320		 * We are resilvering iff:
321		 * 1) We are a replacing vdev (ie our name is "replacing-1" or
322		 *    "spare-1" or something like that), and
323		 * 2) The pool is currently being resilvered.
324		 *
325		 * We cannot simply check vd->vdev_resilver_txg, because it's
326		 * not set in this path.
327		 *
328		 * Nor can we just check our vdev_ops; there are cases (such as
329		 * when a user types "zpool replace pool odev spare_dev" and
330		 * spare_dev is in the spare list, or when a spare device is
331		 * automatically used to replace a DEGRADED device) when
332		 * resilvering is complete but both the original vdev and the
333		 * spare vdev remain in the pool.  That behavior is intentional.
334		 * It helps implement the policy that a spare should be
335		 * automatically removed from the pool after the user replaces
336		 * the device that originally failed.
337		 */
338		boolean_t replacing = (vd->vdev_ops == &vdev_replacing_ops ||
339		    vd->vdev_ops == &vdev_spare_ops) &&
340		    spa_load_state(vd->vdev_spa) == SPA_LOAD_NONE &&
341		    dsl_scan_resilvering(vd->vdev_spa->spa_dsl_pool);
342		mm = vdev_mirror_map_alloc(vd->vdev_children, replacing,
343		    B_FALSE);
344		for (c = 0; c < mm->mm_children; c++) {
345			mc = &mm->mm_child[c];
346			mc->mc_vd = vd->vdev_child[c];
347			mc->mc_offset = zio->io_offset;
348		}
349	}
350
351	zio->io_vsd = mm;
352	zio->io_vsd_ops = &vdev_mirror_vsd_ops;
353	return (mm);
354}
355
356static int
357vdev_mirror_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
358    uint64_t *ashift)
359{
360	int numerrors = 0;
361	int lasterror = 0;
362
363	if (vd->vdev_children == 0) {
364		vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
365		return (SET_ERROR(EINVAL));
366	}
367
368	vdev_open_children(vd);
369
370	for (int c = 0; c < vd->vdev_children; c++) {
371		vdev_t *cvd = vd->vdev_child[c];
372
373		if (cvd->vdev_open_error) {
374			lasterror = cvd->vdev_open_error;
375			numerrors++;
376			continue;
377		}
378
379		*asize = MIN(*asize - 1, cvd->vdev_asize - 1) + 1;
380		*max_asize = MIN(*max_asize - 1, cvd->vdev_max_asize - 1) + 1;
381		*ashift = MAX(*ashift, cvd->vdev_ashift);
382	}
383
384	if (numerrors == vd->vdev_children) {
385		if (vdev_children_are_offline(vd))
386			vd->vdev_stat.vs_aux = VDEV_AUX_CHILDREN_OFFLINE;
387		else
388			vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
389		return (lasterror);
390	}
391
392	return (0);
393}
394
395static void
396vdev_mirror_close(vdev_t *vd)
397{
398	for (int c = 0; c < vd->vdev_children; c++)
399		vdev_close(vd->vdev_child[c]);
400}
401
402static void
403vdev_mirror_child_done(zio_t *zio)
404{
405	mirror_child_t *mc = zio->io_private;
406
407	mc->mc_error = zio->io_error;
408	mc->mc_tried = 1;
409	mc->mc_skipped = 0;
410}
411
412static void
413vdev_mirror_scrub_done(zio_t *zio)
414{
415	mirror_child_t *mc = zio->io_private;
416
417	if (zio->io_error == 0) {
418		zio_t *pio;
419		zio_link_t *zl = NULL;
420
421		mutex_enter(&zio->io_lock);
422		while ((pio = zio_walk_parents(zio, &zl)) != NULL) {
423			mutex_enter(&pio->io_lock);
424			ASSERT3U(zio->io_size, >=, pio->io_size);
425			abd_copy(pio->io_abd, zio->io_abd, pio->io_size);
426			mutex_exit(&pio->io_lock);
427		}
428		mutex_exit(&zio->io_lock);
429	}
430
431	abd_free(zio->io_abd);
432
433	mc->mc_error = zio->io_error;
434	mc->mc_tried = 1;
435	mc->mc_skipped = 0;
436}
437
438/*
439 * Check the other, lower-index DVAs to see if they're on the same
440 * vdev as the child we picked.  If they are, use them since they
441 * are likely to have been allocated from the primary metaslab in
442 * use at the time, and hence are more likely to have locality with
443 * single-copy data.
444 */
445static int
446vdev_mirror_dva_select(zio_t *zio, int p)
447{
448	dva_t *dva = zio->io_bp->blk_dva;
449	mirror_map_t *mm = zio->io_vsd;
450	int preferred;
451	int c;
452
453	preferred = mm->mm_preferred[p];
454	for (p--; p >= 0; p--) {
455		c = mm->mm_preferred[p];
456		if (DVA_GET_VDEV(&dva[c]) == DVA_GET_VDEV(&dva[preferred]))
457			preferred = c;
458	}
459	return (preferred);
460}
461
462static int
463vdev_mirror_preferred_child_randomize(zio_t *zio)
464{
465	mirror_map_t *mm = zio->io_vsd;
466	int p;
467
468	if (mm->mm_root) {
469		p = spa_get_random(mm->mm_preferred_cnt);
470		return (vdev_mirror_dva_select(zio, p));
471	}
472
473	/*
474	 * To ensure we don't always favour the first matching vdev,
475	 * which could lead to wear leveling issues on SSD's, we
476	 * use the I/O offset as a pseudo random seed into the vdevs
477	 * which have the lowest load.
478	 */
479	p = (zio->io_offset >> vdev_mirror_shift) % mm->mm_preferred_cnt;
480	return (mm->mm_preferred[p]);
481}
482
483/*
484 * Try to find a vdev whose DTL doesn't contain the block we want to read
485 * prefering vdevs based on determined load.
486 *
487 * Try to find a child whose DTL doesn't contain the block we want to read.
488 * If we can't, try the read on any vdev we haven't already tried.
489 */
490static int
491vdev_mirror_child_select(zio_t *zio)
492{
493	mirror_map_t *mm = zio->io_vsd;
494	uint64_t txg = zio->io_txg;
495	int c, lowest_load;
496
497	ASSERT(zio->io_bp == NULL || BP_PHYSICAL_BIRTH(zio->io_bp) == txg);
498
499	lowest_load = INT_MAX;
500	mm->mm_preferred_cnt = 0;
501	for (c = 0; c < mm->mm_children; c++) {
502		mirror_child_t *mc;
503
504		mc = &mm->mm_child[c];
505		if (mc->mc_tried || mc->mc_skipped)
506			continue;
507
508		if (mc->mc_vd == NULL || !vdev_readable(mc->mc_vd)) {
509			mc->mc_error = SET_ERROR(ENXIO);
510			mc->mc_tried = 1;	/* don't even try */
511			mc->mc_skipped = 1;
512			continue;
513		}
514
515		if (vdev_dtl_contains(mc->mc_vd, DTL_MISSING, txg, 1)) {
516			mc->mc_error = SET_ERROR(ESTALE);
517			mc->mc_skipped = 1;
518			mc->mc_speculative = 1;
519			continue;
520		}
521
522		mc->mc_load = vdev_mirror_load(mm, mc->mc_vd, mc->mc_offset);
523		if (mc->mc_load > lowest_load)
524			continue;
525
526		if (mc->mc_load < lowest_load) {
527			lowest_load = mc->mc_load;
528			mm->mm_preferred_cnt = 0;
529		}
530		mm->mm_preferred[mm->mm_preferred_cnt] = c;
531		mm->mm_preferred_cnt++;
532	}
533
534	if (mm->mm_preferred_cnt == 1) {
535		MIRROR_BUMP(vdev_mirror_stat_preferred_found);
536		return (mm->mm_preferred[0]);
537	}
538
539	if (mm->mm_preferred_cnt > 1) {
540		MIRROR_BUMP(vdev_mirror_stat_preferred_not_found);
541		return (vdev_mirror_preferred_child_randomize(zio));
542	}
543
544	/*
545	 * Every device is either missing or has this txg in its DTL.
546	 * Look for any child we haven't already tried before giving up.
547	 */
548	for (c = 0; c < mm->mm_children; c++) {
549		if (!mm->mm_child[c].mc_tried)
550			return (c);
551	}
552
553	/*
554	 * Every child failed.  There's no place left to look.
555	 */
556	return (-1);
557}
558
559static void
560vdev_mirror_io_start(zio_t *zio)
561{
562	mirror_map_t *mm;
563	mirror_child_t *mc;
564	int c, children;
565
566	mm = vdev_mirror_map_init(zio);
567
568	if (mm == NULL) {
569		ASSERT(!spa_trust_config(zio->io_spa));
570		ASSERT(zio->io_type == ZIO_TYPE_READ);
571		zio_execute(zio);
572		return;
573	}
574
575	if (zio->io_type == ZIO_TYPE_READ) {
576		if (zio->io_bp != NULL &&
577		    (zio->io_flags & ZIO_FLAG_SCRUB) && !mm->mm_resilvering) {
578			/*
579			 * For scrubbing reads (if we can verify the
580			 * checksum here, as indicated by io_bp being
581			 * non-NULL) we need to allocate a read buffer for
582			 * each child and issue reads to all children.  If
583			 * any child succeeds, it will copy its data into
584			 * zio->io_data in vdev_mirror_scrub_done.
585			 */
586			for (c = 0; c < mm->mm_children; c++) {
587				mc = &mm->mm_child[c];
588				zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
589				    mc->mc_vd, mc->mc_offset,
590				    abd_alloc_sametype(zio->io_abd,
591				    zio->io_size), zio->io_size,
592				    zio->io_type, zio->io_priority, 0,
593				    vdev_mirror_scrub_done, mc));
594			}
595			zio_execute(zio);
596			return;
597		}
598		/*
599		 * For normal reads just pick one child.
600		 */
601		c = vdev_mirror_child_select(zio);
602		children = (c >= 0);
603	} else {
604		ASSERT(zio->io_type == ZIO_TYPE_WRITE);
605
606		/*
607		 * Writes go to all children.
608		 */
609		c = 0;
610		children = mm->mm_children;
611	}
612
613	while (children--) {
614		mc = &mm->mm_child[c];
615		zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
616		    mc->mc_vd, mc->mc_offset, zio->io_abd, zio->io_size,
617		    zio->io_type, zio->io_priority, 0,
618		    vdev_mirror_child_done, mc));
619		c++;
620	}
621
622	zio_execute(zio);
623}
624
625static int
626vdev_mirror_worst_error(mirror_map_t *mm)
627{
628	int error[2] = { 0, 0 };
629
630	for (int c = 0; c < mm->mm_children; c++) {
631		mirror_child_t *mc = &mm->mm_child[c];
632		int s = mc->mc_speculative;
633		error[s] = zio_worst_error(error[s], mc->mc_error);
634	}
635
636	return (error[0] ? error[0] : error[1]);
637}
638
639static void
640vdev_mirror_io_done(zio_t *zio)
641{
642	mirror_map_t *mm = zio->io_vsd;
643	mirror_child_t *mc;
644	int c;
645	int good_copies = 0;
646	int unexpected_errors = 0;
647
648	if (mm == NULL)
649		return;
650
651	for (c = 0; c < mm->mm_children; c++) {
652		mc = &mm->mm_child[c];
653
654		if (mc->mc_error) {
655			if (!mc->mc_skipped)
656				unexpected_errors++;
657		} else if (mc->mc_tried) {
658			good_copies++;
659		}
660	}
661
662	if (zio->io_type == ZIO_TYPE_WRITE) {
663		/*
664		 * XXX -- for now, treat partial writes as success.
665		 *
666		 * Now that we support write reallocation, it would be better
667		 * to treat partial failure as real failure unless there are
668		 * no non-degraded top-level vdevs left, and not update DTLs
669		 * if we intend to reallocate.
670		 */
671		/* XXPOLICY */
672		if (good_copies != mm->mm_children) {
673			/*
674			 * Always require at least one good copy.
675			 *
676			 * For ditto blocks (io_vd == NULL), require
677			 * all copies to be good.
678			 *
679			 * XXX -- for replacing vdevs, there's no great answer.
680			 * If the old device is really dead, we may not even
681			 * be able to access it -- so we only want to
682			 * require good writes to the new device.  But if
683			 * the new device turns out to be flaky, we want
684			 * to be able to detach it -- which requires all
685			 * writes to the old device to have succeeded.
686			 */
687			if (good_copies == 0 || zio->io_vd == NULL)
688				zio->io_error = vdev_mirror_worst_error(mm);
689		}
690		return;
691	}
692
693	ASSERT(zio->io_type == ZIO_TYPE_READ);
694
695	/*
696	 * If we don't have a good copy yet, keep trying other children.
697	 */
698	/* XXPOLICY */
699	if (good_copies == 0 && (c = vdev_mirror_child_select(zio)) != -1) {
700		ASSERT(c >= 0 && c < mm->mm_children);
701		mc = &mm->mm_child[c];
702		zio_vdev_io_redone(zio);
703		zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
704		    mc->mc_vd, mc->mc_offset, zio->io_abd, zio->io_size,
705		    ZIO_TYPE_READ, zio->io_priority, 0,
706		    vdev_mirror_child_done, mc));
707		return;
708	}
709
710	/* XXPOLICY */
711	if (good_copies == 0) {
712		zio->io_error = vdev_mirror_worst_error(mm);
713		ASSERT(zio->io_error != 0);
714	}
715
716	if (good_copies && spa_writeable(zio->io_spa) &&
717	    (unexpected_errors ||
718	    (zio->io_flags & ZIO_FLAG_RESILVER) ||
719	    ((zio->io_flags & ZIO_FLAG_SCRUB) && mm->mm_resilvering))) {
720		/*
721		 * Use the good data we have in hand to repair damaged children.
722		 */
723		for (c = 0; c < mm->mm_children; c++) {
724			/*
725			 * Don't rewrite known good children.
726			 * Not only is it unnecessary, it could
727			 * actually be harmful: if the system lost
728			 * power while rewriting the only good copy,
729			 * there would be no good copies left!
730			 */
731			mc = &mm->mm_child[c];
732
733			if (mc->mc_error == 0) {
734				if (mc->mc_tried)
735					continue;
736				/*
737				 * We didn't try this child.  We need to
738				 * repair it if:
739				 * 1. it's a scrub (in which case we have
740				 * tried everything that was healthy)
741				 *  - or -
742				 * 2. it's an indirect vdev (in which case
743				 * it could point to any other vdev, which
744				 * might have a bad DTL)
745				 *  - or -
746				 * 3. the DTL indicates that this data is
747				 * missing from this vdev
748				 */
749				if (!(zio->io_flags & ZIO_FLAG_SCRUB) &&
750				    mc->mc_vd->vdev_ops != &vdev_indirect_ops &&
751				    !vdev_dtl_contains(mc->mc_vd, DTL_PARTIAL,
752				    zio->io_txg, 1))
753					continue;
754				mc->mc_error = SET_ERROR(ESTALE);
755			}
756
757			zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
758			    mc->mc_vd, mc->mc_offset,
759			    zio->io_abd, zio->io_size,
760			    ZIO_TYPE_WRITE, ZIO_PRIORITY_ASYNC_WRITE,
761			    ZIO_FLAG_IO_REPAIR | (unexpected_errors ?
762			    ZIO_FLAG_SELF_HEAL : 0), NULL, NULL));
763		}
764	}
765}
766
767static void
768vdev_mirror_state_change(vdev_t *vd, int faulted, int degraded)
769{
770	if (faulted == vd->vdev_children) {
771		if (vdev_children_are_offline(vd)) {
772			vdev_set_state(vd, B_FALSE, VDEV_STATE_OFFLINE,
773			    VDEV_AUX_CHILDREN_OFFLINE);
774		} else {
775			vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
776			    VDEV_AUX_NO_REPLICAS);
777		}
778	} else if (degraded + faulted != 0) {
779		vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
780	} else {
781		vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
782	}
783}
784
785static int
786vdev_mirror_dumpio(vdev_t *vd, caddr_t data, size_t size,
787    uint64_t offset, uint64_t origoffset, boolean_t doread, boolean_t isdump)
788{
789	uint64_t numerrors;
790	int err = EIO;
791
792	for (uint64_t c = 0; c < vd->vdev_children; c++) {
793		vdev_t *cvd = vd->vdev_child[c];
794
795		if (cvd->vdev_ops->vdev_op_dumpio == NULL) {
796			err = EINVAL;
797		} else {
798			err = cvd->vdev_ops->vdev_op_dumpio(cvd, data, size,
799			    offset, origoffset, doread, isdump);
800		}
801		if (err != 0) {
802			numerrors++;
803		} else if (doread) {
804			break;
805		}
806	}
807	if (err != 0) {
808		return (SET_ERROR(err));
809	}
810
811	return (0);
812}
813
814vdev_ops_t vdev_mirror_ops = {
815	.vdev_op_open = vdev_mirror_open,
816	.vdev_op_close = vdev_mirror_close,
817	.vdev_op_asize = vdev_default_asize,
818	.vdev_op_io_start = vdev_mirror_io_start,
819	.vdev_op_io_done = vdev_mirror_io_done,
820	.vdev_op_state_change = vdev_mirror_state_change,
821	.vdev_op_need_resilver = NULL,
822	.vdev_op_hold = NULL,
823	.vdev_op_rele = NULL,
824	.vdev_op_remap = NULL,
825	.vdev_op_xlate = vdev_default_xlate,
826	.vdev_op_dumpio = vdev_mirror_dumpio,
827	.vdev_op_type = VDEV_TYPE_MIRROR,	/* name of this vdev type */
828	.vdev_op_leaf = B_FALSE			/* not a leaf vdev */
829};
830
831vdev_ops_t vdev_replacing_ops = {
832	.vdev_op_open = vdev_mirror_open,
833	.vdev_op_close = vdev_mirror_close,
834	.vdev_op_asize = vdev_default_asize,
835	.vdev_op_io_start = vdev_mirror_io_start,
836	.vdev_op_io_done = vdev_mirror_io_done,
837	.vdev_op_state_change = vdev_mirror_state_change,
838	.vdev_op_need_resilver = NULL,
839	.vdev_op_hold = NULL,
840	.vdev_op_rele = NULL,
841	.vdev_op_remap = NULL,
842	.vdev_op_xlate = vdev_default_xlate,
843	.vdev_op_dumpio = vdev_mirror_dumpio,
844	.vdev_op_type = VDEV_TYPE_REPLACING,	/* name of this vdev type */
845	.vdev_op_leaf = B_FALSE			/* not a leaf vdev */
846};
847
848vdev_ops_t vdev_spare_ops = {
849	.vdev_op_open = vdev_mirror_open,
850	.vdev_op_close = vdev_mirror_close,
851	.vdev_op_asize = vdev_default_asize,
852	.vdev_op_io_start = vdev_mirror_io_start,
853	.vdev_op_io_done = vdev_mirror_io_done,
854	.vdev_op_state_change = vdev_mirror_state_change,
855	.vdev_op_need_resilver = NULL,
856	.vdev_op_hold = NULL,
857	.vdev_op_rele = NULL,
858	.vdev_op_remap = NULL,
859	.vdev_op_xlate = vdev_default_xlate,
860	.vdev_op_dumpio = vdev_mirror_dumpio,
861	.vdev_op_type = VDEV_TYPE_SPARE,	/* name of this vdev type */
862	.vdev_op_leaf = B_FALSE			/* not a leaf vdev */
863};
864