xref: /titanic_41/usr/src/uts/common/fs/zfs/vdev_mirror.c (revision efe6bf490da92417f844e59983882a3b1c0b4915)
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, 2014 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
vdev_mirror_map_free(zio_t * zio)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 *
vdev_mirror_map_alloc(zio_t * zio)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
vdev_mirror_open(vdev_t * vd,uint64_t * asize,uint64_t * max_asize,uint64_t * ashift)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
vdev_mirror_close(vdev_t * vd)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
vdev_mirror_child_done(zio_t * zio)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
vdev_mirror_scrub_done(zio_t * zio)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
vdev_mirror_child_select(zio_t * zio)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 void
vdev_mirror_io_start(zio_t * zio)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 			zio_execute(zio);
289 			return;
290 		}
291 		/*
292 		 * For normal reads just pick one child.
293 		 */
294 		c = vdev_mirror_child_select(zio);
295 		children = (c >= 0);
296 	} else {
297 		ASSERT(zio->io_type == ZIO_TYPE_WRITE);
298 
299 		/*
300 		 * Writes go to all children.
301 		 */
302 		c = 0;
303 		children = mm->mm_children;
304 	}
305 
306 	while (children--) {
307 		mc = &mm->mm_child[c];
308 		zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
309 		    mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
310 		    zio->io_type, zio->io_priority, 0,
311 		    vdev_mirror_child_done, mc));
312 		c++;
313 	}
314 
315 	zio_execute(zio);
316 }
317 
318 static int
vdev_mirror_worst_error(mirror_map_t * mm)319 vdev_mirror_worst_error(mirror_map_t *mm)
320 {
321 	int error[2] = { 0, 0 };
322 
323 	for (int c = 0; c < mm->mm_children; c++) {
324 		mirror_child_t *mc = &mm->mm_child[c];
325 		int s = mc->mc_speculative;
326 		error[s] = zio_worst_error(error[s], mc->mc_error);
327 	}
328 
329 	return (error[0] ? error[0] : error[1]);
330 }
331 
332 static void
vdev_mirror_io_done(zio_t * zio)333 vdev_mirror_io_done(zio_t *zio)
334 {
335 	mirror_map_t *mm = zio->io_vsd;
336 	mirror_child_t *mc;
337 	int c;
338 	int good_copies = 0;
339 	int unexpected_errors = 0;
340 
341 	for (c = 0; c < mm->mm_children; c++) {
342 		mc = &mm->mm_child[c];
343 
344 		if (mc->mc_error) {
345 			if (!mc->mc_skipped)
346 				unexpected_errors++;
347 		} else if (mc->mc_tried) {
348 			good_copies++;
349 		}
350 	}
351 
352 	if (zio->io_type == ZIO_TYPE_WRITE) {
353 		/*
354 		 * XXX -- for now, treat partial writes as success.
355 		 *
356 		 * Now that we support write reallocation, it would be better
357 		 * to treat partial failure as real failure unless there are
358 		 * no non-degraded top-level vdevs left, and not update DTLs
359 		 * if we intend to reallocate.
360 		 */
361 		/* XXPOLICY */
362 		if (good_copies != mm->mm_children) {
363 			/*
364 			 * Always require at least one good copy.
365 			 *
366 			 * For ditto blocks (io_vd == NULL), require
367 			 * all copies to be good.
368 			 *
369 			 * XXX -- for replacing vdevs, there's no great answer.
370 			 * If the old device is really dead, we may not even
371 			 * be able to access it -- so we only want to
372 			 * require good writes to the new device.  But if
373 			 * the new device turns out to be flaky, we want
374 			 * to be able to detach it -- which requires all
375 			 * writes to the old device to have succeeded.
376 			 */
377 			if (good_copies == 0 || zio->io_vd == NULL)
378 				zio->io_error = vdev_mirror_worst_error(mm);
379 		}
380 		return;
381 	}
382 
383 	ASSERT(zio->io_type == ZIO_TYPE_READ);
384 
385 	/*
386 	 * If we don't have a good copy yet, keep trying other children.
387 	 */
388 	/* XXPOLICY */
389 	if (good_copies == 0 && (c = vdev_mirror_child_select(zio)) != -1) {
390 		ASSERT(c >= 0 && c < mm->mm_children);
391 		mc = &mm->mm_child[c];
392 		zio_vdev_io_redone(zio);
393 		zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
394 		    mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
395 		    ZIO_TYPE_READ, zio->io_priority, 0,
396 		    vdev_mirror_child_done, mc));
397 		return;
398 	}
399 
400 	/* XXPOLICY */
401 	if (good_copies == 0) {
402 		zio->io_error = vdev_mirror_worst_error(mm);
403 		ASSERT(zio->io_error != 0);
404 	}
405 
406 	if (good_copies && spa_writeable(zio->io_spa) &&
407 	    (unexpected_errors ||
408 	    (zio->io_flags & ZIO_FLAG_RESILVER) ||
409 	    ((zio->io_flags & ZIO_FLAG_SCRUB) && mm->mm_replacing))) {
410 		/*
411 		 * Use the good data we have in hand to repair damaged children.
412 		 */
413 		for (c = 0; c < mm->mm_children; c++) {
414 			/*
415 			 * Don't rewrite known good children.
416 			 * Not only is it unnecessary, it could
417 			 * actually be harmful: if the system lost
418 			 * power while rewriting the only good copy,
419 			 * there would be no good copies left!
420 			 */
421 			mc = &mm->mm_child[c];
422 
423 			if (mc->mc_error == 0) {
424 				if (mc->mc_tried)
425 					continue;
426 				if (!(zio->io_flags & ZIO_FLAG_SCRUB) &&
427 				    !vdev_dtl_contains(mc->mc_vd, DTL_PARTIAL,
428 				    zio->io_txg, 1))
429 					continue;
430 				mc->mc_error = SET_ERROR(ESTALE);
431 			}
432 
433 			zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
434 			    mc->mc_vd, mc->mc_offset,
435 			    zio->io_data, zio->io_size,
436 			    ZIO_TYPE_WRITE, ZIO_PRIORITY_ASYNC_WRITE,
437 			    ZIO_FLAG_IO_REPAIR | (unexpected_errors ?
438 			    ZIO_FLAG_SELF_HEAL : 0), NULL, NULL));
439 		}
440 	}
441 }
442 
443 static void
vdev_mirror_state_change(vdev_t * vd,int faulted,int degraded)444 vdev_mirror_state_change(vdev_t *vd, int faulted, int degraded)
445 {
446 	if (faulted == vd->vdev_children)
447 		vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
448 		    VDEV_AUX_NO_REPLICAS);
449 	else if (degraded + faulted != 0)
450 		vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
451 	else
452 		vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
453 }
454 
455 vdev_ops_t vdev_mirror_ops = {
456 	vdev_mirror_open,
457 	vdev_mirror_close,
458 	vdev_default_asize,
459 	vdev_mirror_io_start,
460 	vdev_mirror_io_done,
461 	vdev_mirror_state_change,
462 	NULL,
463 	NULL,
464 	VDEV_TYPE_MIRROR,	/* name of this vdev type */
465 	B_FALSE			/* not a leaf vdev */
466 };
467 
468 vdev_ops_t vdev_replacing_ops = {
469 	vdev_mirror_open,
470 	vdev_mirror_close,
471 	vdev_default_asize,
472 	vdev_mirror_io_start,
473 	vdev_mirror_io_done,
474 	vdev_mirror_state_change,
475 	NULL,
476 	NULL,
477 	VDEV_TYPE_REPLACING,	/* name of this vdev type */
478 	B_FALSE			/* not a leaf vdev */
479 };
480 
481 vdev_ops_t vdev_spare_ops = {
482 	vdev_mirror_open,
483 	vdev_mirror_close,
484 	vdev_default_asize,
485 	vdev_mirror_io_start,
486 	vdev_mirror_io_done,
487 	vdev_mirror_state_change,
488 	NULL,
489 	NULL,
490 	VDEV_TYPE_SPARE,	/* name of this vdev type */
491 	B_FALSE			/* not a leaf vdev */
492 };
493