1 files changed, 480 insertions, 0 deletions

diff --git a/module/zfs/vdev_mirror.c b/module/zfs/vdev_mirror.c
new file mode 100644
index 000000000..c4629ff45
--- /dev/null
+++ b/module/zfs/vdev_mirror.c
@@ -0,0 +1,480 @@
+/*
+ * 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 2008 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 = zio->io_parent;
+		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);
+	}
+
+	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->vdev_dtl_map, 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);
+
+		/*
+		 * If this is a resilvering I/O to a replacing vdev,
+		 * only the last child should be written -- unless the
+		 * first child happens to have a DTL entry here as well.
+		 * All other writes go to all children.
+		 */
+		if ((zio->io_flags & ZIO_FLAG_RESILVER) && mm->mm_replacing &&
+		    !vdev_dtl_contains(&mm->mm_child[0].mc_vd->vdev_dtl_map,
+		    zio->io_txg, 1)) {
+			c = mm->mm_children - 1;
+			children = 1;
+		} else {
+			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_mode & FWRITE) &&
+	    (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->vdev_dtl_map,
+				    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, 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 */
+};