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 */
29
30 #include <sys/zfs_context.h>
31 #include <sys/spa.h>
32 #include <sys/vdev_impl.h>
33 #include <sys/zio.h>
34 #include <sys/fs/zfs.h>
35
36 /*
37 * Virtual device vector for mirroring.
38 */
39
40 typedef struct mirror_child {
41 vdev_t *mc_vd;
42 uint64_t mc_offset;
43 int mc_error;
44 uint8_t mc_tried;
45 uint8_t mc_skipped;
46 uint8_t mc_speculative;
47 } mirror_child_t;
48
49 typedef struct mirror_map {
50 int mm_children;
51 int mm_replacing;
52 int mm_preferred;
53 int mm_root;
54 mirror_child_t mm_child[1];
55 } mirror_map_t;
56
57 int vdev_mirror_shift = 21;
58
59 static void
60 vdev_mirror_map_free(zio_t *zio)
61 {
62 mirror_map_t *mm = zio->io_vsd;
63
64 kmem_free(mm, offsetof(mirror_map_t, mm_child[mm->mm_children]));
65 }
66
67 static const zio_vsd_ops_t vdev_mirror_vsd_ops = {
68 vdev_mirror_map_free,
69 zio_vsd_default_cksum_report
70 };
71
72 static mirror_map_t *
73 vdev_mirror_map_alloc(zio_t *zio)
74 {
75 mirror_map_t *mm = NULL;
76 mirror_child_t *mc;
77 vdev_t *vd = zio->io_vd;
78 int c, d;
79
80 if (vd == NULL) {
81 dva_t *dva = zio->io_bp->blk_dva;
82 spa_t *spa = zio->io_spa;
83
84 c = BP_GET_NDVAS(zio->io_bp);
85
86 mm = kmem_zalloc(offsetof(mirror_map_t, mm_child[c]), KM_SLEEP);
87 mm->mm_children = c;
88 mm->mm_replacing = B_FALSE;
89 mm->mm_preferred = spa_get_random(c);
90 mm->mm_root = B_TRUE;
91
92 /*
93 * Check the other, lower-index DVAs to see if they're on
94 * the same vdev as the child we picked. If they are, use
95 * them since they are likely to have been allocated from
96 * the primary metaslab in use at the time, and hence are
97 * more likely to have locality with single-copy data.
98 */
99 for (c = mm->mm_preferred, d = c - 1; d >= 0; d--) {
100 if (DVA_GET_VDEV(&dva[d]) == DVA_GET_VDEV(&dva[c]))
101 mm->mm_preferred = d;
102 }
103
104 for (c = 0; c < mm->mm_children; c++) {
105 mc = &mm->mm_child[c];
106
107 mc->mc_vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[c]));
108 mc->mc_offset = DVA_GET_OFFSET(&dva[c]);
109 }
110 } else {
111 c = vd->vdev_children;
112
113 mm = kmem_zalloc(offsetof(mirror_map_t, mm_child[c]), KM_SLEEP);
114 mm->mm_children = c;
115 mm->mm_replacing = (vd->vdev_ops == &vdev_replacing_ops ||
116 vd->vdev_ops == &vdev_spare_ops);
117 mm->mm_preferred = mm->mm_replacing ? 0 :
118 (zio->io_offset >> vdev_mirror_shift) % c;
119 mm->mm_root = B_FALSE;
120
121 for (c = 0; c < mm->mm_children; c++) {
122 mc = &mm->mm_child[c];
123 mc->mc_vd = vd->vdev_child[c];
124 mc->mc_offset = zio->io_offset;
125 }
126 }
127
128 zio->io_vsd = mm;
129 zio->io_vsd_ops = &vdev_mirror_vsd_ops;
130 return (mm);
131 }
132
133 static int
134 vdev_mirror_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
135 uint64_t *ashift)
136 {
137 int numerrors = 0;
138 int lasterror = 0;
139
140 if (vd->vdev_children == 0) {
141 vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
142 return (SET_ERROR(EINVAL));
143 }
144
145 vdev_open_children(vd);
146
147 for (int c = 0; c < vd->vdev_children; c++) {
148 vdev_t *cvd = vd->vdev_child[c];
149
150 if (cvd->vdev_open_error) {
151 lasterror = cvd->vdev_open_error;
152 numerrors++;
153 continue;
154 }
155
156 *asize = MIN(*asize - 1, cvd->vdev_asize - 1) + 1;
157 *max_asize = MIN(*max_asize - 1, cvd->vdev_max_asize - 1) + 1;
158 *ashift = MAX(*ashift, cvd->vdev_ashift);
159 }
160
161 if (numerrors == vd->vdev_children) {
162 vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
163 return (lasterror);
164 }
165
166 return (0);
167 }
168
169 static void
170 vdev_mirror_close(vdev_t *vd)
171 {
172 for (int c = 0; c < vd->vdev_children; c++)
173 vdev_close(vd->vdev_child[c]);
174 }
175
176 static void
177 vdev_mirror_child_done(zio_t *zio)
178 {
179 mirror_child_t *mc = zio->io_private;
180
181 mc->mc_error = zio->io_error;
182 mc->mc_tried = 1;
183 mc->mc_skipped = 0;
184 }
185
186 static void
187 vdev_mirror_scrub_done(zio_t *zio)
188 {
189 mirror_child_t *mc = zio->io_private;
190
191 if (zio->io_error == 0) {
192 zio_t *pio;
193
194 mutex_enter(&zio->io_lock);
195 while ((pio = zio_walk_parents(zio)) != NULL) {
196 mutex_enter(&pio->io_lock);
197 ASSERT3U(zio->io_size, >=, pio->io_size);
198 bcopy(zio->io_data, pio->io_data, pio->io_size);
199 mutex_exit(&pio->io_lock);
200 }
201 mutex_exit(&zio->io_lock);
202 }
203
204 zio_buf_free(zio->io_data, zio->io_size);
205
206 mc->mc_error = zio->io_error;
207 mc->mc_tried = 1;
208 mc->mc_skipped = 0;
209 }
210
211 /*
212 * Try to find a child whose DTL doesn't contain the block we want to read.
213 * If we can't, try the read on any vdev we haven't already tried.
214 */
215 static int
216 vdev_mirror_child_select(zio_t *zio)
217 {
218 mirror_map_t *mm = zio->io_vsd;
219 mirror_child_t *mc;
220 uint64_t txg = zio->io_txg;
221 int i, c;
222
223 ASSERT(zio->io_bp == NULL || BP_PHYSICAL_BIRTH(zio->io_bp) == txg);
224
225 /*
226 * Try to find a child whose DTL doesn't contain the block to read.
227 * If a child is known to be completely inaccessible (indicated by
228 * vdev_readable() returning B_FALSE), don't even try.
229 */
230 for (i = 0, c = mm->mm_preferred; i < mm->mm_children; i++, c++) {
231 if (c >= mm->mm_children)
232 c = 0;
233 mc = &mm->mm_child[c];
234 if (mc->mc_tried || mc->mc_skipped)
235 continue;
236 if (!vdev_readable(mc->mc_vd)) {
237 mc->mc_error = SET_ERROR(ENXIO);
238 mc->mc_tried = 1; /* don't even try */
239 mc->mc_skipped = 1;
240 continue;
241 }
242 if (!vdev_dtl_contains(mc->mc_vd, DTL_MISSING, txg, 1))
243 return (c);
244 mc->mc_error = SET_ERROR(ESTALE);
245 mc->mc_skipped = 1;
246 mc->mc_speculative = 1;
247 }
248
249 /*
250 * Every device is either missing or has this txg in its DTL.
251 * Look for any child we haven't already tried before giving up.
252 */
253 for (c = 0; c < mm->mm_children; c++)
254 if (!mm->mm_child[c].mc_tried)
255 return (c);
256
257 /*
258 * Every child failed. There's no place left to look.
259 */
260 return (-1);
261 }
262
263 static int
264 vdev_mirror_io_start(zio_t *zio)
265 {
266 mirror_map_t *mm;
267 mirror_child_t *mc;
268 int c, children;
269
270 mm = vdev_mirror_map_alloc(zio);
271
272 if (zio->io_type == ZIO_TYPE_READ) {
273 if ((zio->io_flags & ZIO_FLAG_SCRUB) && !mm->mm_replacing) {
274 /*
275 * For scrubbing reads we need to allocate a read
276 * buffer for each child and issue reads to all
277 * children. If any child succeeds, it will copy its
278 * data into zio->io_data in vdev_mirror_scrub_done.
279 */
280 for (c = 0; c < mm->mm_children; c++) {
281 mc = &mm->mm_child[c];
282 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
283 mc->mc_vd, mc->mc_offset,
284 zio_buf_alloc(zio->io_size), zio->io_size,
285 zio->io_type, zio->io_priority, 0,
286 vdev_mirror_scrub_done, mc));
287 }
288 return (ZIO_PIPELINE_CONTINUE);
289 }
290 /*
291 * For normal reads just pick one child.
292 */
293 c = vdev_mirror_child_select(zio);
294 children = (c >= 0);
295 } else {
296 ASSERT(zio->io_type == ZIO_TYPE_WRITE);
297
298 /*
299 * Writes go to all children.
300 */
301 c = 0;
302 children = mm->mm_children;
303 }
304
305 while (children--) {
306 mc = &mm->mm_child[c];
307 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
308 mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
309 zio->io_type, zio->io_priority, 0,
310 vdev_mirror_child_done, mc));
311 c++;
312 }
313
314 return (ZIO_PIPELINE_CONTINUE);
315 }
316
317 static int
318 vdev_mirror_worst_error(mirror_map_t *mm)
319 {
320 int error[2] = { 0, 0 };
321
322 for (int c = 0; c < mm->mm_children; c++) {
323 mirror_child_t *mc = &mm->mm_child[c];
324 int s = mc->mc_speculative;
325 error[s] = zio_worst_error(error[s], mc->mc_error);
326 }
327
328 return (error[0] ? error[0] : error[1]);
329 }
330
331 static void
332 vdev_mirror_io_done(zio_t *zio)
333 {
334 mirror_map_t *mm = zio->io_vsd;
335 mirror_child_t *mc;
336 int c;
337 int good_copies = 0;
338 int unexpected_errors = 0;
339
340 for (c = 0; c < mm->mm_children; c++) {
341 mc = &mm->mm_child[c];
342
343 if (mc->mc_error) {
344 if (!mc->mc_skipped)
345 unexpected_errors++;
346 } else if (mc->mc_tried) {
347 good_copies++;
348 }
349 }
350
351 if (zio->io_type == ZIO_TYPE_WRITE) {
352 /*
353 * XXX -- for now, treat partial writes as success.
354 *
355 * Now that we support write reallocation, it would be better
356 * to treat partial failure as real failure unless there are
357 * no non-degraded top-level vdevs left, and not update DTLs
358 * if we intend to reallocate.
359 */
360 /* XXPOLICY */
361 if (good_copies != mm->mm_children) {
362 /*
363 * Always require at least one good copy.
364 *
365 * For ditto blocks (io_vd == NULL), require
366 * all copies to be good.
367 *
368 * XXX -- for replacing vdevs, there's no great answer.
369 * If the old device is really dead, we may not even
370 * be able to access it -- so we only want to
371 * require good writes to the new device. But if
372 * the new device turns out to be flaky, we want
373 * to be able to detach it -- which requires all
374 * writes to the old device to have succeeded.
375 */
376 if (good_copies == 0 || zio->io_vd == NULL)
377 zio->io_error = vdev_mirror_worst_error(mm);
378 }
379 return;
380 }
381
382 ASSERT(zio->io_type == ZIO_TYPE_READ);
383
384 /*
385 * If we don't have a good copy yet, keep trying other children.
386 */
387 /* XXPOLICY */
388 if (good_copies == 0 && (c = vdev_mirror_child_select(zio)) != -1) {
389 ASSERT(c >= 0 && c < mm->mm_children);
390 mc = &mm->mm_child[c];
391 zio_vdev_io_redone(zio);
392 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
393 mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
394 ZIO_TYPE_READ, zio->io_priority, 0,
395 vdev_mirror_child_done, mc));
396 return;
397 }
398
399 /* XXPOLICY */
400 if (good_copies == 0) {
401 zio->io_error = vdev_mirror_worst_error(mm);
402 ASSERT(zio->io_error != 0);
403 }
404
405 if (good_copies && spa_writeable(zio->io_spa) &&
406 (unexpected_errors ||
407 (zio->io_flags & ZIO_FLAG_RESILVER) ||
408 ((zio->io_flags & ZIO_FLAG_SCRUB) && mm->mm_replacing))) {
409 /*
410 * Use the good data we have in hand to repair damaged children.
411 */
412 for (c = 0; c < mm->mm_children; c++) {
413 /*
414 * Don't rewrite known good children.
415 * Not only is it unnecessary, it could
416 * actually be harmful: if the system lost
417 * power while rewriting the only good copy,
418 * there would be no good copies left!
419 */
420 mc = &mm->mm_child[c];
421
422 if (mc->mc_error == 0) {
423 if (mc->mc_tried)
424 continue;
425 if (!(zio->io_flags & ZIO_FLAG_SCRUB) &&
426 !vdev_dtl_contains(mc->mc_vd, DTL_PARTIAL,
427 zio->io_txg, 1))
428 continue;
429 mc->mc_error = SET_ERROR(ESTALE);
430 }
431
432 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
433 mc->mc_vd, mc->mc_offset,
434 zio->io_data, zio->io_size,
435 ZIO_TYPE_WRITE, zio->io_priority,
436 ZIO_FLAG_IO_REPAIR | (unexpected_errors ?
437 ZIO_FLAG_SELF_HEAL : 0), NULL, NULL));
438 }
439 }
440 }
441
442 static void
443 vdev_mirror_state_change(vdev_t *vd, int faulted, int degraded)
444 {
445 if (faulted == vd->vdev_children)
446 vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
447 VDEV_AUX_NO_REPLICAS);
448 else if (degraded + faulted != 0)
449 vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
450 else
451 vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
452 }
453
454 vdev_ops_t vdev_mirror_ops = {
455 vdev_mirror_open,
456 vdev_mirror_close,
457 vdev_default_asize,
458 vdev_mirror_io_start,
459 vdev_mirror_io_done,
460 vdev_mirror_state_change,
461 NULL,
462 NULL,
463 VDEV_TYPE_MIRROR, /* name of this vdev type */
464 B_FALSE /* not a leaf vdev */
465 };
466
467 vdev_ops_t vdev_replacing_ops = {
468 vdev_mirror_open,
469 vdev_mirror_close,
470 vdev_default_asize,
471 vdev_mirror_io_start,
472 vdev_mirror_io_done,
473 vdev_mirror_state_change,
474 NULL,
475 NULL,
476 VDEV_TYPE_REPLACING, /* name of this vdev type */
477 B_FALSE /* not a leaf vdev */
478 };
479
480 vdev_ops_t vdev_spare_ops = {
481 vdev_mirror_open,
482 vdev_mirror_close,
483 vdev_default_asize,
484 vdev_mirror_io_start,
485 vdev_mirror_io_done,
486 vdev_mirror_state_change,
487 NULL,
488 NULL,
489 VDEV_TYPE_SPARE, /* name of this vdev type */
490 B_FALSE /* not a leaf vdev */
491 };