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.
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.
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]
22 * Copyright 2010 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
27 * Copyright (c) 2013 by Delphix. All rights reserved.
30 #include <sys/zfs_context.h>
32 #include <sys/vdev_impl.h>
34 #include <sys/fs/zfs.h>
37 * Virtual device vector for mirroring.
40 typedef struct mirror_child {
47 uint8_t mc_speculative;
50 typedef struct mirror_map {
55 mirror_child_t mm_child[1];
59 * When the children are equally busy queue incoming requests to a single
60 * child for N microseconds. This is done to maximize the likelihood that
61 * the Linux elevator will be able to merge requests while it is plugged.
62 * Otherwise, requests are queued to the least busy device.
64 * For rotational disks the Linux elevator will plug for 10ms which is
65 * why zfs_vdev_mirror_switch_us is set to 10ms by default. For non-
66 * rotational disks the elevator will not plug, but 10ms is still a small
67 * enough value that the requests will get spread over all the children.
69 * For fast SSDs it may make sense to decrease zfs_vdev_mirror_switch_us
70 * significantly to bound the worst case latencies. It would probably be
71 * ideal to calculate a decaying average of the last observed latencies and
72 * use that to dynamically adjust the zfs_vdev_mirror_switch_us time.
74 int zfs_vdev_mirror_switch_us = 10000;
77 vdev_mirror_map_free(zio_t *zio)
79 mirror_map_t *mm = zio->io_vsd;
81 kmem_free(mm, offsetof(mirror_map_t, mm_child[mm->mm_children]));
84 static const zio_vsd_ops_t vdev_mirror_vsd_ops = {
86 zio_vsd_default_cksum_report
90 vdev_mirror_pending(vdev_t *vd)
92 return (avl_numnodes(&vd->vdev_queue.vq_active_tree));
96 * Avoid inlining the function to keep vdev_mirror_io_start(), which
97 * is this functions only caller, as small as possible on the stack.
99 noinline static mirror_map_t *
100 vdev_mirror_map_alloc(zio_t *zio)
102 mirror_map_t *mm = NULL;
104 vdev_t *vd = zio->io_vd;
108 dva_t *dva = zio->io_bp->blk_dva;
109 spa_t *spa = zio->io_spa;
111 c = BP_GET_NDVAS(zio->io_bp);
113 mm = kmem_zalloc(offsetof(mirror_map_t, mm_child[c]),
116 mm->mm_replacing = B_FALSE;
117 mm->mm_preferred = spa_get_random(c);
118 mm->mm_root = B_TRUE;
121 * Check the other, lower-index DVAs to see if they're on
122 * the same vdev as the child we picked. If they are, use
123 * them since they are likely to have been allocated from
124 * the primary metaslab in use at the time, and hence are
125 * more likely to have locality with single-copy data.
127 for (c = mm->mm_preferred, d = c - 1; d >= 0; d--) {
128 if (DVA_GET_VDEV(&dva[d]) == DVA_GET_VDEV(&dva[c]))
129 mm->mm_preferred = d;
132 for (c = 0; c < mm->mm_children; c++) {
133 mc = &mm->mm_child[c];
135 mc->mc_vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[c]));
136 mc->mc_offset = DVA_GET_OFFSET(&dva[c]);
139 int lowest_pending = INT_MAX;
142 c = vd->vdev_children;
144 mm = kmem_zalloc(offsetof(mirror_map_t, mm_child[c]),
147 mm->mm_replacing = (vd->vdev_ops == &vdev_replacing_ops ||
148 vd->vdev_ops == &vdev_spare_ops);
149 mm->mm_preferred = 0;
150 mm->mm_root = B_FALSE;
152 for (c = 0; c < mm->mm_children; c++) {
153 mc = &mm->mm_child[c];
154 mc->mc_vd = vd->vdev_child[c];
155 mc->mc_offset = zio->io_offset;
157 if (mm->mm_replacing)
160 if (!vdev_readable(mc->mc_vd)) {
161 mc->mc_error = SET_ERROR(ENXIO);
164 mc->mc_pending = INT_MAX;
168 mc->mc_pending = vdev_mirror_pending(mc->mc_vd);
169 if (mc->mc_pending < lowest_pending) {
170 lowest_pending = mc->mc_pending;
172 } else if (mc->mc_pending == lowest_pending) {
177 d = gethrtime() / (NSEC_PER_USEC * zfs_vdev_mirror_switch_us);
178 d = (d % lowest_nr) + 1;
180 for (c = 0; c < mm->mm_children; c++) {
181 mc = &mm->mm_child[c];
183 if (mm->mm_child[c].mc_pending == lowest_pending) {
185 mm->mm_preferred = c;
193 zio->io_vsd_ops = &vdev_mirror_vsd_ops;
198 vdev_mirror_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
205 if (vd->vdev_children == 0) {
206 vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
207 return (SET_ERROR(EINVAL));
210 vdev_open_children(vd);
212 for (c = 0; c < vd->vdev_children; c++) {
213 vdev_t *cvd = vd->vdev_child[c];
215 if (cvd->vdev_open_error) {
216 lasterror = cvd->vdev_open_error;
221 *asize = MIN(*asize - 1, cvd->vdev_asize - 1) + 1;
222 *max_asize = MIN(*max_asize - 1, cvd->vdev_max_asize - 1) + 1;
223 *ashift = MAX(*ashift, cvd->vdev_ashift);
226 if (numerrors == vd->vdev_children) {
227 vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
235 vdev_mirror_close(vdev_t *vd)
239 for (c = 0; c < vd->vdev_children; c++)
240 vdev_close(vd->vdev_child[c]);
244 vdev_mirror_child_done(zio_t *zio)
246 mirror_child_t *mc = zio->io_private;
248 mc->mc_error = zio->io_error;
254 vdev_mirror_scrub_done(zio_t *zio)
256 mirror_child_t *mc = zio->io_private;
258 if (zio->io_error == 0) {
261 mutex_enter(&zio->io_lock);
262 while ((pio = zio_walk_parents(zio)) != NULL) {
263 mutex_enter(&pio->io_lock);
264 ASSERT3U(zio->io_size, >=, pio->io_size);
265 bcopy(zio->io_data, pio->io_data, pio->io_size);
266 mutex_exit(&pio->io_lock);
268 mutex_exit(&zio->io_lock);
271 zio_buf_free(zio->io_data, zio->io_size);
273 mc->mc_error = zio->io_error;
279 * Try to find a child whose DTL doesn't contain the block we want to read.
280 * If we can't, try the read on any vdev we haven't already tried.
283 vdev_mirror_child_select(zio_t *zio)
285 mirror_map_t *mm = zio->io_vsd;
287 uint64_t txg = zio->io_txg;
290 ASSERT(zio->io_bp == NULL || BP_PHYSICAL_BIRTH(zio->io_bp) == txg);
293 * Try to find a child whose DTL doesn't contain the block to read.
294 * If a child is known to be completely inaccessible (indicated by
295 * vdev_readable() returning B_FALSE), don't even try.
297 for (i = 0, c = mm->mm_preferred; i < mm->mm_children; i++, c++) {
298 if (c >= mm->mm_children)
300 mc = &mm->mm_child[c];
301 if (mc->mc_tried || mc->mc_skipped)
303 if (mc->mc_vd == NULL || !vdev_readable(mc->mc_vd)) {
304 mc->mc_error = SET_ERROR(ENXIO);
305 mc->mc_tried = 1; /* don't even try */
309 if (!vdev_dtl_contains(mc->mc_vd, DTL_MISSING, txg, 1))
311 mc->mc_error = SET_ERROR(ESTALE);
313 mc->mc_speculative = 1;
317 * Every device is either missing or has this txg in its DTL.
318 * Look for any child we haven't already tried before giving up.
320 for (c = 0; c < mm->mm_children; c++)
321 if (!mm->mm_child[c].mc_tried)
325 * Every child failed. There's no place left to look.
331 vdev_mirror_io_start(zio_t *zio)
337 mm = vdev_mirror_map_alloc(zio);
339 if (zio->io_type == ZIO_TYPE_READ) {
340 if ((zio->io_flags & ZIO_FLAG_SCRUB) && !mm->mm_replacing) {
342 * For scrubbing reads we need to allocate a read
343 * buffer for each child and issue reads to all
344 * children. If any child succeeds, it will copy its
345 * data into zio->io_data in vdev_mirror_scrub_done.
347 for (c = 0; c < mm->mm_children; c++) {
348 mc = &mm->mm_child[c];
349 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
350 mc->mc_vd, mc->mc_offset,
351 zio_buf_alloc(zio->io_size), zio->io_size,
352 zio->io_type, zio->io_priority, 0,
353 vdev_mirror_scrub_done, mc));
355 return (ZIO_PIPELINE_CONTINUE);
358 * For normal reads just pick one child.
360 c = vdev_mirror_child_select(zio);
363 ASSERT(zio->io_type == ZIO_TYPE_WRITE);
366 * Writes go to all children.
369 children = mm->mm_children;
373 mc = &mm->mm_child[c];
374 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
375 mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
376 zio->io_type, zio->io_priority, 0,
377 vdev_mirror_child_done, mc));
381 return (ZIO_PIPELINE_CONTINUE);
385 vdev_mirror_worst_error(mirror_map_t *mm)
387 int c, error[2] = { 0, 0 };
389 for (c = 0; c < mm->mm_children; c++) {
390 mirror_child_t *mc = &mm->mm_child[c];
391 int s = mc->mc_speculative;
392 error[s] = zio_worst_error(error[s], mc->mc_error);
395 return (error[0] ? error[0] : error[1]);
399 vdev_mirror_io_done(zio_t *zio)
401 mirror_map_t *mm = zio->io_vsd;
405 int unexpected_errors = 0;
407 for (c = 0; c < mm->mm_children; c++) {
408 mc = &mm->mm_child[c];
413 } else if (mc->mc_tried) {
418 if (zio->io_type == ZIO_TYPE_WRITE) {
420 * XXX -- for now, treat partial writes as success.
422 * Now that we support write reallocation, it would be better
423 * to treat partial failure as real failure unless there are
424 * no non-degraded top-level vdevs left, and not update DTLs
425 * if we intend to reallocate.
428 if (good_copies != mm->mm_children) {
430 * Always require at least one good copy.
432 * For ditto blocks (io_vd == NULL), require
433 * all copies to be good.
435 * XXX -- for replacing vdevs, there's no great answer.
436 * If the old device is really dead, we may not even
437 * be able to access it -- so we only want to
438 * require good writes to the new device. But if
439 * the new device turns out to be flaky, we want
440 * to be able to detach it -- which requires all
441 * writes to the old device to have succeeded.
443 if (good_copies == 0 || zio->io_vd == NULL)
444 zio->io_error = vdev_mirror_worst_error(mm);
449 ASSERT(zio->io_type == ZIO_TYPE_READ);
452 * If we don't have a good copy yet, keep trying other children.
455 if (good_copies == 0 && (c = vdev_mirror_child_select(zio)) != -1) {
456 ASSERT(c >= 0 && c < mm->mm_children);
457 mc = &mm->mm_child[c];
458 zio_vdev_io_redone(zio);
459 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
460 mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
461 ZIO_TYPE_READ, zio->io_priority, 0,
462 vdev_mirror_child_done, mc));
467 if (good_copies == 0) {
468 zio->io_error = vdev_mirror_worst_error(mm);
469 ASSERT(zio->io_error != 0);
472 if (good_copies && spa_writeable(zio->io_spa) &&
473 (unexpected_errors ||
474 (zio->io_flags & ZIO_FLAG_RESILVER) ||
475 ((zio->io_flags & ZIO_FLAG_SCRUB) && mm->mm_replacing))) {
477 * Use the good data we have in hand to repair damaged children.
479 for (c = 0; c < mm->mm_children; c++) {
481 * Don't rewrite known good children.
482 * Not only is it unnecessary, it could
483 * actually be harmful: if the system lost
484 * power while rewriting the only good copy,
485 * there would be no good copies left!
487 mc = &mm->mm_child[c];
489 if (mc->mc_error == 0) {
492 if (!(zio->io_flags & ZIO_FLAG_SCRUB) &&
493 !vdev_dtl_contains(mc->mc_vd, DTL_PARTIAL,
496 mc->mc_error = SET_ERROR(ESTALE);
499 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
500 mc->mc_vd, mc->mc_offset,
501 zio->io_data, zio->io_size,
502 ZIO_TYPE_WRITE, ZIO_PRIORITY_ASYNC_WRITE,
503 ZIO_FLAG_IO_REPAIR | (unexpected_errors ?
504 ZIO_FLAG_SELF_HEAL : 0), NULL, NULL));
510 vdev_mirror_state_change(vdev_t *vd, int faulted, int degraded)
512 if (faulted == vd->vdev_children)
513 vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
514 VDEV_AUX_NO_REPLICAS);
515 else if (degraded + faulted != 0)
516 vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
518 vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
521 vdev_ops_t vdev_mirror_ops = {
525 vdev_mirror_io_start,
527 vdev_mirror_state_change,
530 VDEV_TYPE_MIRROR, /* name of this vdev type */
531 B_FALSE /* not a leaf vdev */
534 vdev_ops_t vdev_replacing_ops = {
538 vdev_mirror_io_start,
540 vdev_mirror_state_change,
543 VDEV_TYPE_REPLACING, /* name of this vdev type */
544 B_FALSE /* not a leaf vdev */
547 vdev_ops_t vdev_spare_ops = {
551 vdev_mirror_io_start,
553 vdev_mirror_state_change,
556 VDEV_TYPE_SPARE, /* name of this vdev type */
557 B_FALSE /* not a leaf vdev */
560 #if defined(_KERNEL) && defined(HAVE_SPL)
561 module_param(zfs_vdev_mirror_switch_us, int, 0644);
562 MODULE_PARM_DESC(zfs_vdev_mirror_switch_us, "Switch mirrors every N usecs");