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) 2013 by Delphix. All rights reserved.
28 * Copyright (c) 2013 Steven Hartland. All rights reserved.
29 */
30
31 #include <sys/zfs_context.h>
32 #include <sys/spa.h>
33 #include <sys/vdev_impl.h>
34 #include <sys/zio.h>
35 #include <sys/fs/zfs.h>
36
37 /*
38 * Virtual device vector for mirroring.
39 */
40
41 typedef struct mirror_child {
42 vdev_t *mc_vd;
43 uint64_t mc_offset;
44 int mc_error;
45 int mc_load;
46 uint8_t mc_tried;
47 uint8_t mc_skipped;
48 uint8_t mc_speculative;
49 } mirror_child_t;
50
51 typedef struct mirror_map {
52 int *mm_preferred;
53 int mm_preferred_cnt;
54 int mm_children;
55 boolean_t mm_replacing;
56 boolean_t mm_root;
57 mirror_child_t mm_child[];
58 } mirror_map_t;
59
60 static int vdev_mirror_shift = 21;
61
62 /*
63 * The load configuration settings below are tuned by default for
64 * the case where all devices are of the same rotational type.
65 *
66 * If there is a mixture of rotating and non-rotating media, setting
67 * non_rotating_seek_inc to 0 may well provide better results as it
68 * will direct more reads to the non-rotating vdevs which are more
69 * likely to have a higher performance.
70 */
71
72 /* Rotating media load calculation configuration. */
73 /* Rotating media load increment for non-seeking I/O's. */
74 static int rotating_inc = 0;
75
76 /* Rotating media load increment for seeking I/O's. */
77 static int rotating_seek_inc = 5;
78
79 /*
80 * Offset in bytes from the last I/O which triggers a reduced rotating media
81 * seek increment.
82 */
83 static int rotating_seek_offset = 1 * 1024 * 1024;
84
85 /* Non-rotating media load calculation configuration. */
86 /* Non-rotating media load increment for non-seeking I/O's. */
87 static int non_rotating_inc = 0;
88
89 /* Non-rotating media load increment for seeking I/O's. */
90 static int non_rotating_seek_inc = 1;
91
92 static inline size_t
93 vdev_mirror_map_size(int children)
94 {
95 return (offsetof(mirror_map_t, mm_child[children]) +
96 sizeof (int) * children);
97 }
98
99 static inline mirror_map_t *
100 vdev_mirror_map_alloc(int children, boolean_t replacing, boolean_t root)
101 {
102 mirror_map_t *mm;
103
104 mm = kmem_zalloc(vdev_mirror_map_size(children), KM_SLEEP);
105 mm->mm_children = children;
106 mm->mm_replacing = replacing;
107 mm->mm_root = root;
108 mm->mm_preferred = (int *)((uintptr_t)mm +
109 offsetof(mirror_map_t, mm_child[children]));
110
111 return (mm);
112 }
113
114 static void
115 vdev_mirror_map_free(zio_t *zio)
116 {
117 mirror_map_t *mm = zio->io_vsd;
118
119 kmem_free(mm, vdev_mirror_map_size(mm->mm_children));
120 }
121
122 static const zio_vsd_ops_t vdev_mirror_vsd_ops = {
123 vdev_mirror_map_free,
124 zio_vsd_default_cksum_report
125 };
126
127 static int
128 vdev_mirror_load(mirror_map_t *mm, vdev_t *vd, uint64_t zio_offset)
129 {
130 uint64_t lastoffset;
131 int load;
132
133 /* All DVAs have equal weight at the root. */
134 if (mm->mm_root)
135 return (INT_MAX);
136
137 /*
138 * We don't return INT_MAX if the device is resilvering i.e.
139 * vdev_resilver_txg != 0 as when tested performance was slightly
140 * worse overall when resilvering with compared to without.
141 */
142
143 /* Standard load based on pending queue length. */
144 load = vdev_queue_length(vd);
145 lastoffset = vdev_queue_lastoffset(vd);
146
147 if (vd->vdev_rotation_rate == VDEV_RATE_NON_ROTATING) {
148 /* Non-rotating media. */
149 if (lastoffset == zio_offset)
150 return (load + non_rotating_inc);
151
152 /*
153 * Apply a seek penalty even for non-rotating devices as
154 * sequential I/O'a can be aggregated into fewer operations
155 * on the device, thus avoiding unnecessary per-command
156 * overhead and boosting performance.
157 */
158 return (load + non_rotating_seek_inc);
159 }
160
161 /* Rotating media I/O's which directly follow the last I/O. */
162 if (lastoffset == zio_offset)
163 return (load + rotating_inc);
164
165 /*
166 * Apply half the seek increment to I/O's within seek offset
167 * of the last I/O queued to this vdev as they should incure less
168 * of a seek increment.
169 */
170 if (ABS(lastoffset - zio_offset) < rotating_seek_offset)
171 return (load + (rotating_seek_inc / 2));
172
173 /* Apply the full seek increment to all other I/O's. */
174 return (load + rotating_seek_inc);
175 }
176
177
178 static mirror_map_t *
179 vdev_mirror_map_init(zio_t *zio)
180 {
181 mirror_map_t *mm = NULL;
182 mirror_child_t *mc;
183 vdev_t *vd = zio->io_vd;
184 int c;
185
186 if (vd == NULL) {
187 dva_t *dva = zio->io_bp->blk_dva;
188 spa_t *spa = zio->io_spa;
189
190 mm = vdev_mirror_map_alloc(BP_GET_NDVAS(zio->io_bp), B_FALSE,
191 B_TRUE);
192 for (c = 0; c < mm->mm_children; c++) {
193 mc = &mm->mm_child[c];
194 mc->mc_vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[c]));
195 mc->mc_offset = DVA_GET_OFFSET(&dva[c]);
196 }
197 } else {
198 mm = vdev_mirror_map_alloc(vd->vdev_children,
199 (vd->vdev_ops == &vdev_replacing_ops ||
200 vd->vdev_ops == &vdev_spare_ops), B_FALSE);
201 for (c = 0; c < mm->mm_children; c++) {
202 mc = &mm->mm_child[c];
203 mc->mc_vd = vd->vdev_child[c];
204 mc->mc_offset = zio->io_offset;
205 }
206 }
207
208 zio->io_vsd = mm;
209 zio->io_vsd_ops = &vdev_mirror_vsd_ops;
210 return (mm);
211 }
212
213 static int
214 vdev_mirror_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
215 uint64_t *ashift)
216 {
217 int numerrors = 0;
218 int lasterror = 0;
219
220 if (vd->vdev_children == 0) {
221 vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
222 return (SET_ERROR(EINVAL));
223 }
224
225 vdev_open_children(vd);
226
227 for (int c = 0; c < vd->vdev_children; c++) {
228 vdev_t *cvd = vd->vdev_child[c];
229
230 if (cvd->vdev_open_error) {
231 lasterror = cvd->vdev_open_error;
232 numerrors++;
233 continue;
234 }
235
236 *asize = MIN(*asize - 1, cvd->vdev_asize - 1) + 1;
237 *max_asize = MIN(*max_asize - 1, cvd->vdev_max_asize - 1) + 1;
238 *ashift = MAX(*ashift, cvd->vdev_ashift);
239 }
240
241 if (numerrors == vd->vdev_children) {
242 vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
243 return (lasterror);
244 }
245
246 return (0);
247 }
248
249 static void
250 vdev_mirror_close(vdev_t *vd)
251 {
252 for (int c = 0; c < vd->vdev_children; c++)
253 vdev_close(vd->vdev_child[c]);
254 }
255
256 static void
257 vdev_mirror_child_done(zio_t *zio)
258 {
259 mirror_child_t *mc = zio->io_private;
260
261 mc->mc_error = zio->io_error;
262 mc->mc_tried = 1;
263 mc->mc_skipped = 0;
264 }
265
266 static void
267 vdev_mirror_scrub_done(zio_t *zio)
268 {
269 mirror_child_t *mc = zio->io_private;
270
271 if (zio->io_error == 0) {
272 zio_t *pio;
273
274 mutex_enter(&zio->io_lock);
275 while ((pio = zio_walk_parents(zio)) != NULL) {
276 mutex_enter(&pio->io_lock);
277 ASSERT3U(zio->io_size, >=, pio->io_size);
278 bcopy(zio->io_data, pio->io_data, pio->io_size);
279 mutex_exit(&pio->io_lock);
280 }
281 mutex_exit(&zio->io_lock);
282 }
283
284 zio_buf_free(zio->io_data, zio->io_size);
285
286 mc->mc_error = zio->io_error;
287 mc->mc_tried = 1;
288 mc->mc_skipped = 0;
289 }
290
291 /*
292 * Check the other, lower-index DVAs to see if they're on the same
293 * vdev as the child we picked. If they are, use them since they
294 * are likely to have been allocated from the primary metaslab in
295 * use at the time, and hence are more likely to have locality with
296 * single-copy data.
297 */
298 static int
299 vdev_mirror_dva_select(zio_t *zio, int preferred)
300 {
301 dva_t *dva = zio->io_bp->blk_dva;
302 mirror_map_t *mm = zio->io_vsd;
303 int c;
304
305 for (c = preferred - 1; c >= 0; c--) {
306 if (DVA_GET_VDEV(&dva[c]) == DVA_GET_VDEV(&dva[preferred]))
307 preferred = c;
308 }
309 return (preferred);
310 }
311
312 static int
313 vdev_mirror_preferred_child_randomize(zio_t *zio)
314 {
315 mirror_map_t *mm = zio->io_vsd;
316 int p;
317
318 if (mm->mm_root) {
319 p = spa_get_random(mm->mm_preferred_cnt);
320 return (vdev_mirror_dva_select(zio, mm->mm_preferred[p]));
321 }
322
323 /*
324 * To ensure we don't always favour the first matching vdev,
325 * which could lead to wear leveling issues on SSD's, we
326 * use the I/O offset as a pseudo random seed into the vdevs
327 * which have the lowest load.
328 */
329 p = (zio->io_offset >> vdev_mirror_shift) % mm->mm_preferred_cnt;
330 return (mm->mm_preferred[p]);
331 }
332
333 /*
334 * Try to find a vdev whose DTL doesn't contain the block we want to read
335 * prefering vdevs based on determined load.
336 *
337 * If we can't, try the read on any vdev we haven't already tried.
338 */
339 static int
340 vdev_mirror_child_select(zio_t *zio)
341 {
342 mirror_map_t *mm = zio->io_vsd;
343 uint64_t txg = zio->io_txg;
344 int c, lowest_load;
345
346 ASSERT(zio->io_bp == NULL || BP_PHYSICAL_BIRTH(zio->io_bp) == txg);
347
348 lowest_load = INT_MAX;
349 mm->mm_preferred_cnt = 0;
350 for (c = 0; c < mm->mm_children; c++) {
351 mirror_child_t *mc;
352
353 mc = &mm->mm_child[c];
354 if (mc->mc_tried || mc->mc_skipped)
355 continue;
356
357 if (!vdev_readable(mc->mc_vd)) {
358 mc->mc_error = SET_ERROR(ENXIO);
359 mc->mc_tried = 1; /* don't even try */
360 mc->mc_skipped = 1;
361 continue;
362 }
363
364 if (vdev_dtl_contains(mc->mc_vd, DTL_MISSING, txg, 1)) {
365 mc->mc_error = SET_ERROR(ESTALE);
366 mc->mc_skipped = 1;
367 mc->mc_speculative = 1;
368 continue;
369 }
370
371 mc->mc_load = vdev_mirror_load(mm, mc->mc_vd, mc->mc_offset);
372 if (mc->mc_load > lowest_load)
373 continue;
374
375 if (mc->mc_load < lowest_load) {
376 lowest_load = mc->mc_load;
377 mm->mm_preferred_cnt = 0;
378 }
379 mm->mm_preferred[mm->mm_preferred_cnt] = c;
380 mm->mm_preferred_cnt++;
381 }
382
383 if (mm->mm_preferred_cnt == 1) {
384 vdev_queue_register_lastoffset(
385 mm->mm_child[mm->mm_preferred[0]].mc_vd, zio);
386 return (mm->mm_preferred[0]);
387 }
388
389 if (mm->mm_preferred_cnt > 1) {
390 int c = vdev_mirror_preferred_child_randomize(zio);
391
392 vdev_queue_register_lastoffset(mm->mm_child[c].mc_vd, zio);
393 return (c);
394 }
395
396 /*
397 * Every device is either missing or has this txg in its DTL.
398 * Look for any child we haven't already tried before giving up.
399 */
400 for (c = 0; c < mm->mm_children; c++) {
401 if (!mm->mm_child[c].mc_tried) {
402 vdev_queue_register_lastoffset(mm->mm_child[c].mc_vd,
403 zio);
404 return (c);
405 }
406 }
407
408 /*
409 * Every child failed. There's no place left to look.
410 */
411 return (-1);
412 }
413
414 static int
415 vdev_mirror_io_start(zio_t *zio)
416 {
417 mirror_map_t *mm;
418 mirror_child_t *mc;
419 int c, children;
420
421 mm = vdev_mirror_map_init(zio);
422
423 if (zio->io_type == ZIO_TYPE_READ) {
424 if ((zio->io_flags & ZIO_FLAG_SCRUB) && !mm->mm_replacing) {
425 /*
426 * For scrubbing reads we need to allocate a read
427 * buffer for each child and issue reads to all
428 * children. If any child succeeds, it will copy its
429 * data into zio->io_data in vdev_mirror_scrub_done.
430 */
431 for (c = 0; c < mm->mm_children; c++) {
432 mc = &mm->mm_child[c];
433 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
434 mc->mc_vd, mc->mc_offset,
435 zio_buf_alloc(zio->io_size), zio->io_size,
436 zio->io_type, zio->io_priority, 0,
437 vdev_mirror_scrub_done, mc));
438 }
439 return (ZIO_PIPELINE_CONTINUE);
440 }
441 /*
442 * For normal reads just pick one child.
443 */
444 c = vdev_mirror_child_select(zio);
445 children = (c >= 0);
446 } else {
447 ASSERT(zio->io_type == ZIO_TYPE_WRITE);
448
449 /*
450 * Writes go to all children.
451 */
452 c = 0;
453 children = mm->mm_children;
454 }
455
456 while (children--) {
457 mc = &mm->mm_child[c];
458 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
459 mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
460 zio->io_type, zio->io_priority, 0,
461 vdev_mirror_child_done, mc));
462 c++;
463 }
464
465 return (ZIO_PIPELINE_CONTINUE);
466 }
467
468 static int
469 vdev_mirror_worst_error(mirror_map_t *mm)
470 {
471 int error[2] = { 0, 0 };
472
473 for (int c = 0; c < mm->mm_children; c++) {
474 mirror_child_t *mc = &mm->mm_child[c];
475 int s = mc->mc_speculative;
476 error[s] = zio_worst_error(error[s], mc->mc_error);
477 }
478
479 return (error[0] ? error[0] : error[1]);
480 }
481
482 static void
483 vdev_mirror_io_done(zio_t *zio)
484 {
485 mirror_map_t *mm = zio->io_vsd;
486 mirror_child_t *mc;
487 int c;
488 int good_copies = 0;
489 int unexpected_errors = 0;
490
491 for (c = 0; c < mm->mm_children; c++) {
492 mc = &mm->mm_child[c];
493
494 if (mc->mc_error) {
495 if (!mc->mc_skipped)
496 unexpected_errors++;
497 } else if (mc->mc_tried) {
498 good_copies++;
499 }
500 }
501
502 if (zio->io_type == ZIO_TYPE_WRITE) {
503 /*
504 * XXX -- for now, treat partial writes as success.
505 *
506 * Now that we support write reallocation, it would be better
507 * to treat partial failure as real failure unless there are
508 * no non-degraded top-level vdevs left, and not update DTLs
509 * if we intend to reallocate.
510 */
511 /* XXPOLICY */
512 if (good_copies != mm->mm_children) {
513 /*
514 * Always require at least one good copy.
515 *
516 * For ditto blocks (io_vd == NULL), require
517 * all copies to be good.
518 *
519 * XXX -- for replacing vdevs, there's no great answer.
520 * If the old device is really dead, we may not even
521 * be able to access it -- so we only want to
522 * require good writes to the new device. But if
523 * the new device turns out to be flaky, we want
524 * to be able to detach it -- which requires all
525 * writes to the old device to have succeeded.
526 */
527 if (good_copies == 0 || zio->io_vd == NULL)
528 zio->io_error = vdev_mirror_worst_error(mm);
529 }
530 return;
531 }
532
533 ASSERT(zio->io_type == ZIO_TYPE_READ);
534
535 /*
536 * If we don't have a good copy yet, keep trying other children.
537 */
538 /* XXPOLICY */
539 if (good_copies == 0 && (c = vdev_mirror_child_select(zio)) != -1) {
540 ASSERT(c >= 0 && c < mm->mm_children);
541 mc = &mm->mm_child[c];
542 zio_vdev_io_redone(zio);
543 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
544 mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
545 ZIO_TYPE_READ, zio->io_priority, 0,
546 vdev_mirror_child_done, mc));
547 return;
548 }
549
550 /* XXPOLICY */
551 if (good_copies == 0) {
552 zio->io_error = vdev_mirror_worst_error(mm);
553 ASSERT(zio->io_error != 0);
554 }
555
556 if (good_copies && spa_writeable(zio->io_spa) &&
557 (unexpected_errors ||
558 (zio->io_flags & ZIO_FLAG_RESILVER) ||
559 ((zio->io_flags & ZIO_FLAG_SCRUB) && mm->mm_replacing))) {
560 /*
561 * Use the good data we have in hand to repair damaged children.
562 */
563 for (c = 0; c < mm->mm_children; c++) {
564 /*
565 * Don't rewrite known good children.
566 * Not only is it unnecessary, it could
567 * actually be harmful: if the system lost
568 * power while rewriting the only good copy,
569 * there would be no good copies left!
570 */
571 mc = &mm->mm_child[c];
572
573 if (mc->mc_error == 0) {
574 if (mc->mc_tried)
575 continue;
576 if (!(zio->io_flags & ZIO_FLAG_SCRUB) &&
577 !vdev_dtl_contains(mc->mc_vd, DTL_PARTIAL,
578 zio->io_txg, 1))
579 continue;
580 mc->mc_error = SET_ERROR(ESTALE);
581 }
582
583 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
584 mc->mc_vd, mc->mc_offset,
585 zio->io_data, zio->io_size,
586 ZIO_TYPE_WRITE, ZIO_PRIORITY_ASYNC_WRITE,
587 ZIO_FLAG_IO_REPAIR | (unexpected_errors ?
588 ZIO_FLAG_SELF_HEAL : 0), NULL, NULL));
589 }
590 }
591 }
592
593 static void
594 vdev_mirror_state_change(vdev_t *vd, int faulted, int degraded)
595 {
596 if (faulted == vd->vdev_children)
597 vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
598 VDEV_AUX_NO_REPLICAS);
599 else if (degraded + faulted != 0)
600 vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
601 else
602 vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
603 }
604
605 vdev_ops_t vdev_mirror_ops = {
606 vdev_mirror_open,
607 vdev_mirror_close,
608 vdev_default_asize,
609 vdev_mirror_io_start,
610 vdev_mirror_io_done,
611 vdev_mirror_state_change,
612 NULL,
613 NULL,
614 VDEV_TYPE_MIRROR, /* name of this vdev type */
615 B_FALSE /* not a leaf vdev */
616 };
617
618 vdev_ops_t vdev_replacing_ops = {
619 vdev_mirror_open,
620 vdev_mirror_close,
621 vdev_default_asize,
622 vdev_mirror_io_start,
623 vdev_mirror_io_done,
624 vdev_mirror_state_change,
625 NULL,
626 NULL,
627 VDEV_TYPE_REPLACING, /* name of this vdev type */
628 B_FALSE /* not a leaf vdev */
629 };
630
631 vdev_ops_t vdev_spare_ops = {
632 vdev_mirror_open,
633 vdev_mirror_close,
634 vdev_default_asize,
635 vdev_mirror_io_start,
636 vdev_mirror_io_done,
637 vdev_mirror_state_change,
638 NULL,
639 NULL,
640 VDEV_TYPE_SPARE, /* name of this vdev type */
641 B_FALSE /* not a leaf vdev */
642 };