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 2009 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 #include <sys/zfs_context.h>
27 #include <sys/spa.h>
28 #include <sys/vdev_impl.h>
29 #include <sys/zio.h>
30 #include <sys/fs/zfs.h>
31
32 /*
33 * Virtual device vector for mirroring.
34 */
35
36 typedef struct mirror_child {
37 vdev_t *mc_vd;
38 uint64_t mc_offset;
39 int mc_error;
40 uint8_t mc_tried;
41 uint8_t mc_skipped;
42 uint8_t mc_speculative;
43 } mirror_child_t;
44
45 typedef struct mirror_map {
46 int mm_children;
47 int mm_replacing;
48 int mm_preferred;
49 int mm_root;
50 mirror_child_t mm_child[1];
51 } mirror_map_t;
52
53 int vdev_mirror_shift = 21;
54
55 static void
vdev_mirror_map_free(zio_t * zio)56 vdev_mirror_map_free(zio_t *zio)
57 {
58 mirror_map_t *mm = zio->io_vsd;
59
60 kmem_free(mm, offsetof(mirror_map_t, mm_child[mm->mm_children]));
61 }
62
63 static const zio_vsd_ops_t vdev_mirror_vsd_ops = {
64 vdev_mirror_map_free,
65 zio_vsd_default_cksum_report
66 };
67
68 static mirror_map_t *
vdev_mirror_map_alloc(zio_t * zio)69 vdev_mirror_map_alloc(zio_t *zio)
70 {
71 mirror_map_t *mm = NULL;
72 mirror_child_t *mc;
73 vdev_t *vd = zio->io_vd;
74 int c, d;
75
76 if (vd == NULL) {
77 dva_t *dva = zio->io_bp->blk_dva;
78 spa_t *spa = zio->io_spa;
79
80 c = BP_GET_NDVAS(zio->io_bp);
81
82 mm = kmem_zalloc(offsetof(mirror_map_t, mm_child[c]), KM_SLEEP);
83 mm->mm_children = c;
84 mm->mm_replacing = B_FALSE;
85 mm->mm_preferred = spa_get_random(c);
86 mm->mm_root = B_TRUE;
87
88 /*
89 * Check the other, lower-index DVAs to see if they're on
90 * the same vdev as the child we picked. If they are, use
91 * them since they are likely to have been allocated from
92 * the primary metaslab in use at the time, and hence are
93 * more likely to have locality with single-copy data.
94 */
95 for (c = mm->mm_preferred, d = c - 1; d >= 0; d--) {
96 if (DVA_GET_VDEV(&dva[d]) == DVA_GET_VDEV(&dva[c]))
97 mm->mm_preferred = d;
98 }
99
100 for (c = 0; c < mm->mm_children; c++) {
101 mc = &mm->mm_child[c];
102
103 mc->mc_vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[c]));
104 mc->mc_offset = DVA_GET_OFFSET(&dva[c]);
105 }
106 } else {
107 c = vd->vdev_children;
108
109 mm = kmem_zalloc(offsetof(mirror_map_t, mm_child[c]), KM_SLEEP);
110 mm->mm_children = c;
111 mm->mm_replacing = (vd->vdev_ops == &vdev_replacing_ops ||
112 vd->vdev_ops == &vdev_spare_ops);
113 mm->mm_preferred = mm->mm_replacing ? 0 :
114 (zio->io_offset >> vdev_mirror_shift) % c;
115 mm->mm_root = B_FALSE;
116
117 for (c = 0; c < mm->mm_children; c++) {
118 mc = &mm->mm_child[c];
119 mc->mc_vd = vd->vdev_child[c];
120 mc->mc_offset = zio->io_offset;
121 }
122 }
123
124 zio->io_vsd = mm;
125 zio->io_vsd_ops = &vdev_mirror_vsd_ops;
126 return (mm);
127 }
128
129 static int
vdev_mirror_open(vdev_t * vd,uint64_t * asize,uint64_t * ashift)130 vdev_mirror_open(vdev_t *vd, uint64_t *asize, uint64_t *ashift)
131 {
132 int numerrors = 0;
133 int lasterror = 0;
134
135 if (vd->vdev_children == 0) {
136 vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
137 return (EINVAL);
138 }
139
140 vdev_open_children(vd);
141
142 for (int c = 0; c < vd->vdev_children; c++) {
143 vdev_t *cvd = vd->vdev_child[c];
144
145 if (cvd->vdev_open_error) {
146 lasterror = cvd->vdev_open_error;
147 numerrors++;
148 continue;
149 }
150
151 *asize = MIN(*asize - 1, cvd->vdev_asize - 1) + 1;
152 *ashift = MAX(*ashift, cvd->vdev_ashift);
153 }
154
155 if (numerrors == vd->vdev_children) {
156 vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
157 return (lasterror);
158 }
159
160 return (0);
161 }
162
163 static void
vdev_mirror_close(vdev_t * vd)164 vdev_mirror_close(vdev_t *vd)
165 {
166 for (int c = 0; c < vd->vdev_children; c++)
167 vdev_close(vd->vdev_child[c]);
168 }
169
170 static void
vdev_mirror_child_done(zio_t * zio)171 vdev_mirror_child_done(zio_t *zio)
172 {
173 mirror_child_t *mc = zio->io_private;
174
175 mc->mc_error = zio->io_error;
176 mc->mc_tried = 1;
177 mc->mc_skipped = 0;
178 }
179
180 static void
vdev_mirror_scrub_done(zio_t * zio)181 vdev_mirror_scrub_done(zio_t *zio)
182 {
183 mirror_child_t *mc = zio->io_private;
184
185 if (zio->io_error == 0) {
186 zio_t *pio;
187
188 mutex_enter(&zio->io_lock);
189 while ((pio = zio_walk_parents(zio)) != NULL) {
190 mutex_enter(&pio->io_lock);
191 ASSERT3U(zio->io_size, >=, pio->io_size);
192 bcopy(zio->io_data, pio->io_data, pio->io_size);
193 mutex_exit(&pio->io_lock);
194 }
195 mutex_exit(&zio->io_lock);
196 }
197
198 zio_buf_free(zio->io_data, zio->io_size);
199
200 mc->mc_error = zio->io_error;
201 mc->mc_tried = 1;
202 mc->mc_skipped = 0;
203 }
204
205 /*
206 * Try to find a child whose DTL doesn't contain the block we want to read.
207 * If we can't, try the read on any vdev we haven't already tried.
208 */
209 static int
vdev_mirror_child_select(zio_t * zio)210 vdev_mirror_child_select(zio_t *zio)
211 {
212 mirror_map_t *mm = zio->io_vsd;
213 mirror_child_t *mc;
214 uint64_t txg = zio->io_txg;
215 int i, c;
216
217 ASSERT(zio->io_bp == NULL || BP_PHYSICAL_BIRTH(zio->io_bp) == txg);
218
219 /*
220 * Try to find a child whose DTL doesn't contain the block to read.
221 * If a child is known to be completely inaccessible (indicated by
222 * vdev_readable() returning B_FALSE), don't even try.
223 */
224 for (i = 0, c = mm->mm_preferred; i < mm->mm_children; i++, c++) {
225 if (c >= mm->mm_children)
226 c = 0;
227 mc = &mm->mm_child[c];
228 if (mc->mc_tried || mc->mc_skipped)
229 continue;
230 if (!vdev_readable(mc->mc_vd)) {
231 mc->mc_error = ENXIO;
232 mc->mc_tried = 1; /* don't even try */
233 mc->mc_skipped = 1;
234 continue;
235 }
236 if (!vdev_dtl_contains(mc->mc_vd, DTL_MISSING, txg, 1))
237 return (c);
238 mc->mc_error = ESTALE;
239 mc->mc_skipped = 1;
240 mc->mc_speculative = 1;
241 }
242
243 /*
244 * Every device is either missing or has this txg in its DTL.
245 * Look for any child we haven't already tried before giving up.
246 */
247 for (c = 0; c < mm->mm_children; c++)
248 if (!mm->mm_child[c].mc_tried)
249 return (c);
250
251 /*
252 * Every child failed. There's no place left to look.
253 */
254 return (-1);
255 }
256
257 static int
vdev_mirror_io_start(zio_t * zio)258 vdev_mirror_io_start(zio_t *zio)
259 {
260 mirror_map_t *mm;
261 mirror_child_t *mc;
262 int c, children;
263
264 mm = vdev_mirror_map_alloc(zio);
265
266 if (zio->io_type == ZIO_TYPE_READ) {
267 if ((zio->io_flags & ZIO_FLAG_SCRUB) && !mm->mm_replacing) {
268 /*
269 * For scrubbing reads we need to allocate a read
270 * buffer for each child and issue reads to all
271 * children. If any child succeeds, it will copy its
272 * data into zio->io_data in vdev_mirror_scrub_done.
273 */
274 for (c = 0; c < mm->mm_children; c++) {
275 mc = &mm->mm_child[c];
276 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
277 mc->mc_vd, mc->mc_offset,
278 zio_buf_alloc(zio->io_size), zio->io_size,
279 zio->io_type, zio->io_priority, 0,
280 vdev_mirror_scrub_done, mc));
281 }
282 return (ZIO_PIPELINE_CONTINUE);
283 }
284 /*
285 * For normal reads just pick one child.
286 */
287 c = vdev_mirror_child_select(zio);
288 children = (c >= 0);
289 } else {
290 ASSERT(zio->io_type == ZIO_TYPE_WRITE);
291
292 /*
293 * Writes go to all children.
294 */
295 c = 0;
296 children = mm->mm_children;
297 }
298
299 while (children--) {
300 mc = &mm->mm_child[c];
301 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
302 mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
303 zio->io_type, zio->io_priority, 0,
304 vdev_mirror_child_done, mc));
305 c++;
306 }
307
308 return (ZIO_PIPELINE_CONTINUE);
309 }
310
311 static int
vdev_mirror_worst_error(mirror_map_t * mm)312 vdev_mirror_worst_error(mirror_map_t *mm)
313 {
314 int error[2] = { 0, 0 };
315
316 for (int c = 0; c < mm->mm_children; c++) {
317 mirror_child_t *mc = &mm->mm_child[c];
318 int s = mc->mc_speculative;
319 error[s] = zio_worst_error(error[s], mc->mc_error);
320 }
321
322 return (error[0] ? error[0] : error[1]);
323 }
324
325 static void
vdev_mirror_io_done(zio_t * zio)326 vdev_mirror_io_done(zio_t *zio)
327 {
328 mirror_map_t *mm = zio->io_vsd;
329 mirror_child_t *mc;
330 int c;
331 int good_copies = 0;
332 int unexpected_errors = 0;
333
334 for (c = 0; c < mm->mm_children; c++) {
335 mc = &mm->mm_child[c];
336
337 if (mc->mc_error) {
338 if (!mc->mc_skipped)
339 unexpected_errors++;
340 } else if (mc->mc_tried) {
341 good_copies++;
342 }
343 }
344
345 if (zio->io_type == ZIO_TYPE_WRITE) {
346 /*
347 * XXX -- for now, treat partial writes as success.
348 *
349 * Now that we support write reallocation, it would be better
350 * to treat partial failure as real failure unless there are
351 * no non-degraded top-level vdevs left, and not update DTLs
352 * if we intend to reallocate.
353 */
354 /* XXPOLICY */
355 if (good_copies != mm->mm_children) {
356 /*
357 * Always require at least one good copy.
358 *
359 * For ditto blocks (io_vd == NULL), require
360 * all copies to be good.
361 *
362 * XXX -- for replacing vdevs, there's no great answer.
363 * If the old device is really dead, we may not even
364 * be able to access it -- so we only want to
365 * require good writes to the new device. But if
366 * the new device turns out to be flaky, we want
367 * to be able to detach it -- which requires all
368 * writes to the old device to have succeeded.
369 */
370 if (good_copies == 0 || zio->io_vd == NULL)
371 zio->io_error = vdev_mirror_worst_error(mm);
372 }
373 return;
374 }
375
376 ASSERT(zio->io_type == ZIO_TYPE_READ);
377
378 /*
379 * If we don't have a good copy yet, keep trying other children.
380 */
381 /* XXPOLICY */
382 if (good_copies == 0 && (c = vdev_mirror_child_select(zio)) != -1) {
383 ASSERT(c >= 0 && c < mm->mm_children);
384 mc = &mm->mm_child[c];
385 zio_vdev_io_redone(zio);
386 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
387 mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
388 ZIO_TYPE_READ, zio->io_priority, 0,
389 vdev_mirror_child_done, mc));
390 return;
391 }
392
393 /* XXPOLICY */
394 if (good_copies == 0) {
395 zio->io_error = vdev_mirror_worst_error(mm);
396 ASSERT(zio->io_error != 0);
397 }
398
399 if (good_copies && spa_writeable(zio->io_spa) &&
400 (unexpected_errors ||
401 (zio->io_flags & ZIO_FLAG_RESILVER) ||
402 ((zio->io_flags & ZIO_FLAG_SCRUB) && mm->mm_replacing))) {
403 /*
404 * Use the good data we have in hand to repair damaged children.
405 */
406 for (c = 0; c < mm->mm_children; c++) {
407 /*
408 * Don't rewrite known good children.
409 * Not only is it unnecessary, it could
410 * actually be harmful: if the system lost
411 * power while rewriting the only good copy,
412 * there would be no good copies left!
413 */
414 mc = &mm->mm_child[c];
415
416 if (mc->mc_error == 0) {
417 if (mc->mc_tried)
418 continue;
419 if (!(zio->io_flags & ZIO_FLAG_SCRUB) &&
420 !vdev_dtl_contains(mc->mc_vd, DTL_PARTIAL,
421 zio->io_txg, 1))
422 continue;
423 mc->mc_error = ESTALE;
424 }
425
426 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
427 mc->mc_vd, mc->mc_offset,
428 zio->io_data, zio->io_size,
429 ZIO_TYPE_WRITE, zio->io_priority,
430 ZIO_FLAG_IO_REPAIR | (unexpected_errors ?
431 ZIO_FLAG_SELF_HEAL : 0), NULL, NULL));
432 }
433 }
434 }
435
436 static void
vdev_mirror_state_change(vdev_t * vd,int faulted,int degraded)437 vdev_mirror_state_change(vdev_t *vd, int faulted, int degraded)
438 {
439 if (faulted == vd->vdev_children)
440 vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
441 VDEV_AUX_NO_REPLICAS);
442 else if (degraded + faulted != 0)
443 vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
444 else
445 vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
446 }
447
448 vdev_ops_t vdev_mirror_ops = {
449 vdev_mirror_open,
450 vdev_mirror_close,
451 vdev_default_asize,
452 vdev_mirror_io_start,
453 vdev_mirror_io_done,
454 vdev_mirror_state_change,
455 VDEV_TYPE_MIRROR, /* name of this vdev type */
456 B_FALSE /* not a leaf vdev */
457 };
458
459 vdev_ops_t vdev_replacing_ops = {
460 vdev_mirror_open,
461 vdev_mirror_close,
462 vdev_default_asize,
463 vdev_mirror_io_start,
464 vdev_mirror_io_done,
465 vdev_mirror_state_change,
466 VDEV_TYPE_REPLACING, /* name of this vdev type */
467 B_FALSE /* not a leaf vdev */
468 };
469
470 vdev_ops_t vdev_spare_ops = {
471 vdev_mirror_open,
472 vdev_mirror_close,
473 vdev_default_asize,
474 vdev_mirror_io_start,
475 vdev_mirror_io_done,
476 vdev_mirror_state_change,
477 VDEV_TYPE_SPARE, /* name of this vdev type */
478 B_FALSE /* not a leaf vdev */
479 };
480