[mirror_zfs.git] / module / zfs / vdev_mirror.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/zfs_context.h>
#include <sys/spa.h>
#include <sys/vdev_impl.h>
#include <sys/zio.h>
#include <sys/fs/zfs.h>

/*
 * Virtual device vector for mirroring.
 */

typedef struct mirror_child {
	vdev_t		*mc_vd;
	uint64_t	mc_offset;
	int		mc_error;
	uint8_t		mc_tried;
	uint8_t		mc_skipped;
	uint8_t		mc_speculative;
} mirror_child_t;

typedef struct mirror_map {
	int		mm_children;
	int		mm_replacing;
	int		mm_preferred;
	int		mm_root;
	mirror_child_t	mm_child[1];
} mirror_map_t;

int vdev_mirror_shift = 21;

static void
vdev_mirror_map_free(zio_t *zio)
{
	mirror_map_t *mm = zio->io_vsd;

	kmem_free(mm, offsetof(mirror_map_t, mm_child[mm->mm_children]));
}

static mirror_map_t *
vdev_mirror_map_alloc(zio_t *zio)
{
	mirror_map_t *mm = NULL;
	mirror_child_t *mc;
	vdev_t *vd = zio->io_vd;
	int c, d;

	if (vd == NULL) {
		dva_t *dva = zio->io_bp->blk_dva;
		spa_t *spa = zio->io_spa;

		c = BP_GET_NDVAS(zio->io_bp);

		mm = kmem_zalloc(offsetof(mirror_map_t, mm_child[c]), KM_SLEEP);
		mm->mm_children = c;
		mm->mm_replacing = B_FALSE;
		mm->mm_preferred = spa_get_random(c);
		mm->mm_root = B_TRUE;

		/*
		 * Check the other, lower-index DVAs to see if they're on
		 * the same vdev as the child we picked.  If they are, use
		 * them since they are likely to have been allocated from
		 * the primary metaslab in use at the time, and hence are
		 * more likely to have locality with single-copy data.
		 */
		for (c = mm->mm_preferred, d = c - 1; d >= 0; d--) {
			if (DVA_GET_VDEV(&dva[d]) == DVA_GET_VDEV(&dva[c]))
				mm->mm_preferred = d;
		}

		for (c = 0; c < mm->mm_children; c++) {
			mc = &mm->mm_child[c];

			mc->mc_vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[c]));
			mc->mc_offset = DVA_GET_OFFSET(&dva[c]);
		}
	} else {
		c = vd->vdev_children;

		mm = kmem_zalloc(offsetof(mirror_map_t, mm_child[c]), KM_SLEEP);
		mm->mm_children = c;
		mm->mm_replacing = (vd->vdev_ops == &vdev_replacing_ops ||
		    vd->vdev_ops == &vdev_spare_ops);
		mm->mm_preferred = mm->mm_replacing ? 0 :
		    (zio->io_offset >> vdev_mirror_shift) % c;
		mm->mm_root = B_FALSE;

		for (c = 0; c < mm->mm_children; c++) {
			mc = &mm->mm_child[c];
			mc->mc_vd = vd->vdev_child[c];
			mc->mc_offset = zio->io_offset;
		}
	}

	zio->io_vsd = mm;
	zio->io_vsd_free = vdev_mirror_map_free;
	return (mm);
}

static int
vdev_mirror_open(vdev_t *vd, uint64_t *asize, uint64_t *ashift)
{
	vdev_t *cvd;
	uint64_t c;
	int numerrors = 0;
	int ret, lasterror = 0;

	if (vd->vdev_children == 0) {
		vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
		return (EINVAL);
	}

	for (c = 0; c < vd->vdev_children; c++) {
		cvd = vd->vdev_child[c];

		if ((ret = vdev_open(cvd)) != 0) {
			lasterror = ret;
			numerrors++;
			continue;
		}

		*asize = MIN(*asize - 1, cvd->vdev_asize - 1) + 1;
		*ashift = MAX(*ashift, cvd->vdev_ashift);
	}

	if (numerrors == vd->vdev_children) {
		vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
		return (lasterror);
	}

	return (0);
}

static void
vdev_mirror_close(vdev_t *vd)
{
	uint64_t c;

	for (c = 0; c < vd->vdev_children; c++)
		vdev_close(vd->vdev_child[c]);
}

static void
vdev_mirror_child_done(zio_t *zio)
{
	mirror_child_t *mc = zio->io_private;

	mc->mc_error = zio->io_error;
	mc->mc_tried = 1;
	mc->mc_skipped = 0;
}

static void
vdev_mirror_scrub_done(zio_t *zio)
{
	mirror_child_t *mc = zio->io_private;

	if (zio->io_error == 0) {
		zio_t *pio;

		mutex_enter(&zio->io_lock);
		while ((pio = zio_walk_parents(zio)) != NULL) {
			mutex_enter(&pio->io_lock);
			ASSERT3U(zio->io_size, >=, pio->io_size);
			bcopy(zio->io_data, pio->io_data, pio->io_size);
			mutex_exit(&pio->io_lock);
		}
		mutex_exit(&zio->io_lock);
	}

	zio_buf_free(zio->io_data, zio->io_size);

	mc->mc_error = zio->io_error;
	mc->mc_tried = 1;
	mc->mc_skipped = 0;
}

/*
 * Try to find a child whose DTL doesn't contain the block we want to read.
 * If we can't, try the read on any vdev we haven't already tried.
 */
static int
vdev_mirror_child_select(zio_t *zio)
{
	mirror_map_t *mm = zio->io_vsd;
	mirror_child_t *mc;
	uint64_t txg = zio->io_txg;
	int i, c;

	ASSERT(zio->io_bp == NULL || zio->io_bp->blk_birth == txg);

	/*
	 * Try to find a child whose DTL doesn't contain the block to read.
	 * If a child is known to be completely inaccessible (indicated by
	 * vdev_readable() returning B_FALSE), don't even try.
	 */
	for (i = 0, c = mm->mm_preferred; i < mm->mm_children; i++, c++) {
		if (c >= mm->mm_children)
			c = 0;
		mc = &mm->mm_child[c];
		if (mc->mc_tried || mc->mc_skipped)
			continue;
		if (!vdev_readable(mc->mc_vd)) {
			mc->mc_error = ENXIO;
			mc->mc_tried = 1;	/* don't even try */
			mc->mc_skipped = 1;
			continue;
		}
		if (!vdev_dtl_contains(mc->mc_vd, DTL_MISSING, txg, 1))
			return (c);
		mc->mc_error = ESTALE;
		mc->mc_skipped = 1;
		mc->mc_speculative = 1;
	}

	/*
	 * Every device is either missing or has this txg in its DTL.
	 * Look for any child we haven't already tried before giving up.
	 */
	for (c = 0; c < mm->mm_children; c++)
		if (!mm->mm_child[c].mc_tried)
			return (c);

	/*
	 * Every child failed.  There's no place left to look.
	 */
	return (-1);
}

static int
vdev_mirror_io_start(zio_t *zio)
{
	mirror_map_t *mm;
	mirror_child_t *mc;
	int c, children;

	mm = vdev_mirror_map_alloc(zio);

	if (zio->io_type == ZIO_TYPE_READ) {
		if ((zio->io_flags & ZIO_FLAG_SCRUB) && !mm->mm_replacing) {
			/*
			 * For scrubbing reads we need to allocate a read
			 * buffer for each child and issue reads to all
			 * children.  If any child succeeds, it will copy its
			 * data into zio->io_data in vdev_mirror_scrub_done.
			 */
			for (c = 0; c < mm->mm_children; c++) {
				mc = &mm->mm_child[c];
				zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
				    mc->mc_vd, mc->mc_offset,
				    zio_buf_alloc(zio->io_size), zio->io_size,
				    zio->io_type, zio->io_priority, 0,
				    vdev_mirror_scrub_done, mc));
			}
			return (ZIO_PIPELINE_CONTINUE);
		}
		/*
		 * For normal reads just pick one child.
		 */
		c = vdev_mirror_child_select(zio);
		children = (c >= 0);
	} else {
		ASSERT(zio->io_type == ZIO_TYPE_WRITE);

		/*
		 * Writes go to all children.
		 */
		c = 0;
		children = mm->mm_children;
	}

	while (children--) {
		mc = &mm->mm_child[c];
		zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
		    mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
		    zio->io_type, zio->io_priority, 0,
		    vdev_mirror_child_done, mc));
		c++;
	}

	return (ZIO_PIPELINE_CONTINUE);
}

static int
vdev_mirror_worst_error(mirror_map_t *mm)
{
	int error[2] = { 0, 0 };

	for (int c = 0; c < mm->mm_children; c++) {
		mirror_child_t *mc = &mm->mm_child[c];
		int s = mc->mc_speculative;
		error[s] = zio_worst_error(error[s], mc->mc_error);
	}

	return (error[0] ? error[0] : error[1]);
}

static void
vdev_mirror_io_done(zio_t *zio)
{
	mirror_map_t *mm = zio->io_vsd;
	mirror_child_t *mc;
	int c;
	int good_copies = 0;
	int unexpected_errors = 0;

	for (c = 0; c < mm->mm_children; c++) {
		mc = &mm->mm_child[c];

		if (mc->mc_error) {
			if (!mc->mc_skipped)
				unexpected_errors++;
		} else if (mc->mc_tried) {
			good_copies++;
		}
	}

	if (zio->io_type == ZIO_TYPE_WRITE) {
		/*
		 * XXX -- for now, treat partial writes as success.
		 *
		 * Now that we support write reallocation, it would be better
		 * to treat partial failure as real failure unless there are
		 * no non-degraded top-level vdevs left, and not update DTLs
		 * if we intend to reallocate.
		 */
		/* XXPOLICY */
		if (good_copies != mm->mm_children) {
			/*
			 * Always require at least one good copy.
			 *
			 * For ditto blocks (io_vd == NULL), require
			 * all copies to be good.
			 *
			 * XXX -- for replacing vdevs, there's no great answer.
			 * If the old device is really dead, we may not even
			 * be able to access it -- so we only want to
			 * require good writes to the new device.  But if
			 * the new device turns out to be flaky, we want
			 * to be able to detach it -- which requires all
			 * writes to the old device to have succeeded.
			 */
			if (good_copies == 0 || zio->io_vd == NULL)
				zio->io_error = vdev_mirror_worst_error(mm);
		}
		return;
	}

	ASSERT(zio->io_type == ZIO_TYPE_READ);

	/*
	 * If we don't have a good copy yet, keep trying other children.
	 */
	/* XXPOLICY */
	if (good_copies == 0 && (c = vdev_mirror_child_select(zio)) != -1) {
		ASSERT(c >= 0 && c < mm->mm_children);
		mc = &mm->mm_child[c];
		zio_vdev_io_redone(zio);
		zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
		    mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
		    ZIO_TYPE_READ, zio->io_priority, 0,
		    vdev_mirror_child_done, mc));
		return;
	}

	/* XXPOLICY */
	if (good_copies == 0) {
		zio->io_error = vdev_mirror_worst_error(mm);
		ASSERT(zio->io_error != 0);
	}

	if (good_copies && spa_writeable(zio->io_spa) &&
	    (unexpected_errors ||
	    (zio->io_flags & ZIO_FLAG_RESILVER) ||
	    ((zio->io_flags & ZIO_FLAG_SCRUB) && mm->mm_replacing))) {
		/*
		 * Use the good data we have in hand to repair damaged children.
		 */
		for (c = 0; c < mm->mm_children; c++) {
			/*
			 * Don't rewrite known good children.
			 * Not only is it unnecessary, it could
			 * actually be harmful: if the system lost
			 * power while rewriting the only good copy,
			 * there would be no good copies left!
			 */
			mc = &mm->mm_child[c];

			if (mc->mc_error == 0) {
				if (mc->mc_tried)
					continue;
				if (!(zio->io_flags & ZIO_FLAG_SCRUB) &&
				    !vdev_dtl_contains(mc->mc_vd, DTL_PARTIAL,
				    zio->io_txg, 1))
					continue;
				mc->mc_error = ESTALE;
			}

			zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
			    mc->mc_vd, mc->mc_offset,
			    zio->io_data, zio->io_size,
			    ZIO_TYPE_WRITE, zio->io_priority,
			    ZIO_FLAG_IO_REPAIR | (unexpected_errors ?
			    ZIO_FLAG_SELF_HEAL : 0), NULL, NULL));
		}
	}
}

static void
vdev_mirror_state_change(vdev_t *vd, int faulted, int degraded)
{
	if (faulted == vd->vdev_children)
		vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
		    VDEV_AUX_NO_REPLICAS);
	else if (degraded + faulted != 0)
		vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
	else
		vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
}

vdev_ops_t vdev_mirror_ops = {
	vdev_mirror_open,
	vdev_mirror_close,
	vdev_default_asize,
	vdev_mirror_io_start,
	vdev_mirror_io_done,
	vdev_mirror_state_change,
	VDEV_TYPE_MIRROR,	/* name of this vdev type */
	B_FALSE			/* not a leaf vdev */
};

vdev_ops_t vdev_replacing_ops = {
	vdev_mirror_open,
	vdev_mirror_close,
	vdev_default_asize,
	vdev_mirror_io_start,
	vdev_mirror_io_done,
	vdev_mirror_state_change,
	VDEV_TYPE_REPLACING,	/* name of this vdev type */
	B_FALSE			/* not a leaf vdev */
};

vdev_ops_t vdev_spare_ops = {
	vdev_mirror_open,
	vdev_mirror_close,
	vdev_default_asize,
	vdev_mirror_io_start,
	vdev_mirror_io_done,
	vdev_mirror_state_change,
	VDEV_TYPE_SPARE,	/* name of this vdev type */
	B_FALSE			/* not a leaf vdev */
};
Commit	Line	Data
34dc7c2f BB	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	/*
d164b209	22	* Copyright 2009 Sun Microsystems, Inc. All rights reserved.
34dc7c2f BB	23	* Use is subject to license terms.
	24	*/
	25
34dc7c2f BB	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;
b128c09f BB	40	uint8_t mc_tried;
	41	uint8_t mc_skipped;
	42	uint8_t mc_speculative;
34dc7c2f BB	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
b128c09f BB	55	static void
	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
34dc7c2f BB	63	static mirror_map_t *
	64	vdev_mirror_map_alloc(zio_t *zio)
	65	{
	66	mirror_map_t *mm = NULL;
	67	mirror_child_t *mc;
	68	vdev_t *vd = zio->io_vd;
	69	int c, d;
	70
	71	if (vd == NULL) {
	72	dva_t *dva = zio->io_bp->blk_dva;
	73	spa_t *spa = zio->io_spa;
	74
	75	c = BP_GET_NDVAS(zio->io_bp);
	76
	77	mm = kmem_zalloc(offsetof(mirror_map_t, mm_child[c]), KM_SLEEP);
	78	mm->mm_children = c;
	79	mm->mm_replacing = B_FALSE;
	80	mm->mm_preferred = spa_get_random(c);
	81	mm->mm_root = B_TRUE;
	82
	83	/*
	84	* Check the other, lower-index DVAs to see if they're on
	85	* the same vdev as the child we picked. If they are, use
	86	* them since they are likely to have been allocated from
	87	* the primary metaslab in use at the time, and hence are
	88	* more likely to have locality with single-copy data.
	89	*/
	90	for (c = mm->mm_preferred, d = c - 1; d >= 0; d--) {
	91	if (DVA_GET_VDEV(&dva[d]) == DVA_GET_VDEV(&dva[c]))
	92	mm->mm_preferred = d;
	93	}
	94
	95	for (c = 0; c < mm->mm_children; c++) {
	96	mc = &mm->mm_child[c];
	97
	98	mc->mc_vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[c]));
	99	mc->mc_offset = DVA_GET_OFFSET(&dva[c]);
	100	}
	101	} else {
	102	c = vd->vdev_children;
	103
	104	mm = kmem_zalloc(offsetof(mirror_map_t, mm_child[c]), KM_SLEEP);
	105	mm->mm_children = c;
	106	mm->mm_replacing = (vd->vdev_ops == &vdev_replacing_ops \|\|
	107	vd->vdev_ops == &vdev_spare_ops);
	108	mm->mm_preferred = mm->mm_replacing ? 0 :
	109	(zio->io_offset >> vdev_mirror_shift) % c;
	110	mm->mm_root = B_FALSE;
	111
	112	for (c = 0; c < mm->mm_children; c++) {
	113	mc = &mm->mm_child[c];
	114	mc->mc_vd = vd->vdev_child[c];
	115	mc->mc_offset = zio->io_offset;
	116	}
	117	}
	118
	119	zio->io_vsd = mm;
b128c09f	120	zio->io_vsd_free = vdev_mirror_map_free;
34dc7c2f BB	121	return (mm);
	122	}
	123
34dc7c2f BB	124	static int
	125	vdev_mirror_open(vdev_t vd, uint64_t asize, uint64_t *ashift)
	126	{
	127	vdev_t *cvd;
	128	uint64_t c;
	129	int numerrors = 0;
	130	int ret, lasterror = 0;
	131
	132	if (vd->vdev_children == 0) {
	133	vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
	134	return (EINVAL);
	135	}
	136
	137	for (c = 0; c < vd->vdev_children; c++) {
	138	cvd = vd->vdev_child[c];
	139
	140	if ((ret = vdev_open(cvd)) != 0) {
	141	lasterror = ret;
	142	numerrors++;
	143	continue;
	144	}
	145
	146	asize = MIN(asize - 1, cvd->vdev_asize - 1) + 1;
	147	ashift = MAX(ashift, cvd->vdev_ashift);
	148	}
	149
	150	if (numerrors == vd->vdev_children) {
	151	vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
	152	return (lasterror);
	153	}
	154
	155	return (0);
	156	}
	157
	158	static void
	159	vdev_mirror_close(vdev_t *vd)
	160	{
	161	uint64_t c;
	162
	163	for (c = 0; c < vd->vdev_children; c++)
	164	vdev_close(vd->vdev_child[c]);
	165	}
	166
	167	static void
	168	vdev_mirror_child_done(zio_t *zio)
	169	{
	170	mirror_child_t *mc = zio->io_private;
	171
	172	mc->mc_error = zio->io_error;
	173	mc->mc_tried = 1;
	174	mc->mc_skipped = 0;
	175	}
	176
	177	static void
	178	vdev_mirror_scrub_done(zio_t *zio)
	179	{
	180	mirror_child_t *mc = zio->io_private;
	181
	182	if (zio->io_error == 0) {
d164b209 BB	183	zio_t *pio;
	184
	185	mutex_enter(&zio->io_lock);
	186	while ((pio = zio_walk_parents(zio)) != NULL) {
	187	mutex_enter(&pio->io_lock);
	188	ASSERT3U(zio->io_size, >=, pio->io_size);
	189	bcopy(zio->io_data, pio->io_data, pio->io_size);
	190	mutex_exit(&pio->io_lock);
	191	}
	192	mutex_exit(&zio->io_lock);
34dc7c2f BB	193	}
	194
	195	zio_buf_free(zio->io_data, zio->io_size);
	196
	197	mc->mc_error = zio->io_error;
	198	mc->mc_tried = 1;
	199	mc->mc_skipped = 0;
	200	}
	201
34dc7c2f BB	202	/*
	203	* Try to find a child whose DTL doesn't contain the block we want to read.
	204	* If we can't, try the read on any vdev we haven't already tried.
	205	*/
	206	static int
	207	vdev_mirror_child_select(zio_t *zio)
	208	{
	209	mirror_map_t *mm = zio->io_vsd;
	210	mirror_child_t *mc;
	211	uint64_t txg = zio->io_txg;
	212	int i, c;
	213
	214	ASSERT(zio->io_bp == NULL \|\| zio->io_bp->blk_birth == txg);
	215
	216	/*
	217	* Try to find a child whose DTL doesn't contain the block to read.
	218	* If a child is known to be completely inaccessible (indicated by
	219	* vdev_readable() returning B_FALSE), don't even try.
	220	*/
	221	for (i = 0, c = mm->mm_preferred; i < mm->mm_children; i++, c++) {
	222	if (c >= mm->mm_children)
	223	c = 0;
	224	mc = &mm->mm_child[c];
	225	if (mc->mc_tried \|\| mc->mc_skipped)
	226	continue;
b128c09f	227	if (!vdev_readable(mc->mc_vd)) {
34dc7c2f BB	228	mc->mc_error = ENXIO;
	229	mc->mc_tried = 1; /* don't even try */
	230	mc->mc_skipped = 1;
	231	continue;
	232	}
fb5f0bc8	233	if (!vdev_dtl_contains(mc->mc_vd, DTL_MISSING, txg, 1))
34dc7c2f BB	234	return (c);
	235	mc->mc_error = ESTALE;
	236	mc->mc_skipped = 1;
b128c09f	237	mc->mc_speculative = 1;
34dc7c2f BB	238	}
	239
	240	/*
	241	* Every device is either missing or has this txg in its DTL.
	242	* Look for any child we haven't already tried before giving up.
	243	*/
	244	for (c = 0; c < mm->mm_children; c++)
	245	if (!mm->mm_child[c].mc_tried)
	246	return (c);
	247
	248	/*
	249	* Every child failed. There's no place left to look.
	250	*/
	251	return (-1);
	252	}
	253
	254	static int
	255	vdev_mirror_io_start(zio_t *zio)
	256	{
	257	mirror_map_t *mm;
	258	mirror_child_t *mc;
	259	int c, children;
	260
	261	mm = vdev_mirror_map_alloc(zio);
	262
	263	if (zio->io_type == ZIO_TYPE_READ) {
	264	if ((zio->io_flags & ZIO_FLAG_SCRUB) && !mm->mm_replacing) {
	265	/*
	266	* For scrubbing reads we need to allocate a read
	267	* buffer for each child and issue reads to all
	268	* children. If any child succeeds, it will copy its
	269	* data into zio->io_data in vdev_mirror_scrub_done.
	270	*/
	271	for (c = 0; c < mm->mm_children; c++) {
	272	mc = &mm->mm_child[c];
	273	zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
	274	mc->mc_vd, mc->mc_offset,
	275	zio_buf_alloc(zio->io_size), zio->io_size,
b128c09f	276	zio->io_type, zio->io_priority, 0,
34dc7c2f BB	277	vdev_mirror_scrub_done, mc));
34dc7c2f BB	278	}
b128c09f	279	return (ZIO_PIPELINE_CONTINUE);
34dc7c2f BB	280	}
	281	/*
	282	* For normal reads just pick one child.
	283	*/
	284	c = vdev_mirror_child_select(zio);
	285	children = (c >= 0);
	286	} else {
	287	ASSERT(zio->io_type == ZIO_TYPE_WRITE);
	288
	289	/*
fb5f0bc8	290	* Writes go to all children.
34dc7c2f	291	*/
fb5f0bc8 BB	292	c = 0;
fb5f0bc8 BB	293	children = mm->mm_children;
34dc7c2f BB	294	}
	295
	296	while (children--) {
	297	mc = &mm->mm_child[c];
	298	zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
b128c09f BB	299	mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
	300	zio->io_type, zio->io_priority, 0,
	301	vdev_mirror_child_done, mc));
34dc7c2f BB	302	c++;
	303	}
	304
b128c09f	305	return (ZIO_PIPELINE_CONTINUE);
34dc7c2f BB	306	}
	307
	308	static int
b128c09f BB	309	vdev_mirror_worst_error(mirror_map_t *mm)
	310	{
	311	int error[2] = { 0, 0 };
	312
	313	for (int c = 0; c < mm->mm_children; c++) {
	314	mirror_child_t *mc = &mm->mm_child[c];
	315	int s = mc->mc_speculative;
	316	error[s] = zio_worst_error(error[s], mc->mc_error);
	317	}
	318
	319	return (error[0] ? error[0] : error[1]);
	320	}
	321
	322	static void
34dc7c2f BB	323	vdev_mirror_io_done(zio_t *zio)
	324	{
	325	mirror_map_t *mm = zio->io_vsd;
	326	mirror_child_t *mc;
	327	int c;
	328	int good_copies = 0;
	329	int unexpected_errors = 0;
	330
34dc7c2f BB	331	for (c = 0; c < mm->mm_children; c++) {
	332	mc = &mm->mm_child[c];
	333
34dc7c2f	334	if (mc->mc_error) {
34dc7c2f BB	335	if (!mc->mc_skipped)
34dc7c2f BB	336	unexpected_errors++;
b128c09f BB	337	} else if (mc->mc_tried) {
b128c09f BB	338	good_copies++;
34dc7c2f BB	339	}
	340	}
	341
	342	if (zio->io_type == ZIO_TYPE_WRITE) {
	343	/*
	344	* XXX -- for now, treat partial writes as success.
b128c09f BB	345	*
	346	* Now that we support write reallocation, it would be better
	347	* to treat partial failure as real failure unless there are
	348	* no non-degraded top-level vdevs left, and not update DTLs
	349	* if we intend to reallocate.
34dc7c2f BB	350	*/
34dc7c2f BB	351	/* XXPOLICY */
b128c09f BB	352	if (good_copies != mm->mm_children) {
	353	/*
	354	* Always require at least one good copy.
	355	*
	356	* For ditto blocks (io_vd == NULL), require
	357	* all copies to be good.
	358	*
	359	* XXX -- for replacing vdevs, there's no great answer.
	360	* If the old device is really dead, we may not even
	361	* be able to access it -- so we only want to
	362	* require good writes to the new device. But if
	363	* the new device turns out to be flaky, we want
	364	* to be able to detach it -- which requires all
	365	* writes to the old device to have succeeded.
	366	*/
	367	if (good_copies == 0 \|\| zio->io_vd == NULL)
	368	zio->io_error = vdev_mirror_worst_error(mm);
	369	}
	370	return;
34dc7c2f BB	371	}
	372
	373	ASSERT(zio->io_type == ZIO_TYPE_READ);
	374
	375	/*
	376	* If we don't have a good copy yet, keep trying other children.
	377	*/
	378	/* XXPOLICY */
	379	if (good_copies == 0 && (c = vdev_mirror_child_select(zio)) != -1) {
	380	ASSERT(c >= 0 && c < mm->mm_children);
	381	mc = &mm->mm_child[c];
34dc7c2f BB	382	zio_vdev_io_redone(zio);
	383	zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
	384	mc->mc_vd, mc->mc_offset, zio->io_data, zio->io_size,
b128c09f	385	ZIO_TYPE_READ, zio->io_priority, 0,
34dc7c2f	386	vdev_mirror_child_done, mc));
b128c09f	387	return;
34dc7c2f BB	388	}
	389
	390	/* XXPOLICY */
b128c09f BB	391	if (good_copies == 0) {
b128c09f BB	392	zio->io_error = vdev_mirror_worst_error(mm);
34dc7c2f	393	ASSERT(zio->io_error != 0);
b128c09f	394	}
34dc7c2f	395
fb5f0bc8	396	if (good_copies && spa_writeable(zio->io_spa) &&
34dc7c2f BB	397	(unexpected_errors \|\|
	398	(zio->io_flags & ZIO_FLAG_RESILVER) \|\|
	399	((zio->io_flags & ZIO_FLAG_SCRUB) && mm->mm_replacing))) {
34dc7c2f BB	400	/*
34dc7c2f BB	401	* Use the good data we have in hand to repair damaged children.
34dc7c2f	402	*/
34dc7c2f BB	403	for (c = 0; c < mm->mm_children; c++) {
	404	/*
	405	* Don't rewrite known good children.
	406	* Not only is it unnecessary, it could
	407	* actually be harmful: if the system lost
	408	* power while rewriting the only good copy,
	409	* there would be no good copies left!
	410	*/
	411	mc = &mm->mm_child[c];
	412
	413	if (mc->mc_error == 0) {
	414	if (mc->mc_tried)
	415	continue;
	416	if (!(zio->io_flags & ZIO_FLAG_SCRUB) &&
fb5f0bc8	417	!vdev_dtl_contains(mc->mc_vd, DTL_PARTIAL,
34dc7c2f BB	418	zio->io_txg, 1))
	419	continue;
	420	mc->mc_error = ESTALE;
	421	}
	422
b128c09f BB	423	zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
	424	mc->mc_vd, mc->mc_offset,
	425	zio->io_data, zio->io_size,
34dc7c2f	426	ZIO_TYPE_WRITE, zio->io_priority,
fb5f0bc8 BB	427	ZIO_FLAG_IO_REPAIR \| (unexpected_errors ?
fb5f0bc8 BB	428	ZIO_FLAG_SELF_HEAL : 0), NULL, NULL));
34dc7c2f	429	}
34dc7c2f	430	}
34dc7c2f BB	431	}
	432
	433	static void
	434	vdev_mirror_state_change(vdev_t *vd, int faulted, int degraded)
	435	{
	436	if (faulted == vd->vdev_children)
	437	vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
	438	VDEV_AUX_NO_REPLICAS);
	439	else if (degraded + faulted != 0)
	440	vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
	441	else
	442	vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
	443	}
	444
	445	vdev_ops_t vdev_mirror_ops = {
	446	vdev_mirror_open,
	447	vdev_mirror_close,
34dc7c2f BB	448	vdev_default_asize,
	449	vdev_mirror_io_start,
	450	vdev_mirror_io_done,
	451	vdev_mirror_state_change,
	452	VDEV_TYPE_MIRROR, /* name of this vdev type */
	453	B_FALSE /* not a leaf vdev */
	454	};
	455
	456	vdev_ops_t vdev_replacing_ops = {
	457	vdev_mirror_open,
	458	vdev_mirror_close,
34dc7c2f BB	459	vdev_default_asize,
	460	vdev_mirror_io_start,
	461	vdev_mirror_io_done,
	462	vdev_mirror_state_change,
	463	VDEV_TYPE_REPLACING, /* name of this vdev type */
	464	B_FALSE /* not a leaf vdev */
	465	};
	466
	467	vdev_ops_t vdev_spare_ops = {
	468	vdev_mirror_open,
	469	vdev_mirror_close,
34dc7c2f BB	470	vdev_default_asize,
	471	vdev_mirror_io_start,
	472	vdev_mirror_io_done,
	473	vdev_mirror_state_change,
	474	VDEV_TYPE_SPARE, /* name of this vdev type */
	475	B_FALSE /* not a leaf vdev */
	476	};