Enable splitting mirrors with indirect vdevs

When a top-level vdev is removed from a pool it is converted to an
indirect vdev. Until now splitting such mirrored pools was not possible
with zpool split. This patch enables handling of indirect vdevs and
splitting of those pools with zpool split.

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: George Amanakis <gamanakis@gmail.com>
Closes #10283

lib/libzfs/libzfs_pool.c

@@ -3452,7 +3452,13 @@ zpool_vdev_split(zpool_handle_t *zhp, char *newname, nvlist_t **newroot,
 		lastlog = 0;
 		verify(nvlist_lookup_string(child[c], ZPOOL_CONFIG_TYPE, &type)
 		    == 0);
-		if (strcmp(type, VDEV_TYPE_MIRROR) != 0) {
+
+		if (strcmp(type, VDEV_TYPE_INDIRECT) == 0) {
+			vdev = child[c];
+			if (nvlist_dup(vdev, &varray[vcount++], 0) != 0)
+				goto out;
+			continue;
+		} else if (strcmp(type, VDEV_TYPE_MIRROR) != 0) {
 			zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
 			    "Source pool must be composed only of mirrors\n"));
 			retval = zfs_error(hdl, EZFS_INVALCONFIG, msg);

module/zfs/spa.c

@@ -7297,7 +7297,8 @@ spa_vdev_split_mirror(spa_t *spa, char *newname, nvlist_t *config,
 		vdev_t *vd = rvd->vdev_child[c];
 
 		/* don't count the holes & logs as children */
-		if (vd->vdev_islog || !vdev_is_concrete(vd)) {
+		if (vd->vdev_islog || (vd->vdev_ops != &vdev_indirect_ops &&
+		    !vdev_is_concrete(vd))) {
 			if (lastlog == 0)
 				lastlog = c;
 			continue;
@@ -7333,6 +7334,11 @@ spa_vdev_split_mirror(spa_t *spa, char *newname, nvlist_t *config,
 			}
 		}
 
+		/* deal with indirect vdevs */
+		if (spa->spa_root_vdev->vdev_child[c]->vdev_ops ==
+		    &vdev_indirect_ops)
+			continue;
+
 		/* which disk is going to be split? */
 		if (nvlist_lookup_uint64(child[c], ZPOOL_CONFIG_GUID,
 		    &glist[c]) != 0) {
@@ -7460,7 +7466,7 @@ spa_vdev_split_mirror(spa_t *spa, char *newname, nvlist_t *config,
 	    offsetof(vdev_t, vdev_trim_node));
 
 	for (c = 0; c < children; c++) {
-		if (vml[c] != NULL) {
+		if (vml[c] != NULL && vml[c]->vdev_ops != &vdev_indirect_ops) {
 			mutex_enter(&vml[c]->vdev_initialize_lock);
 			vdev_initialize_stop(vml[c],
 			    VDEV_INITIALIZE_ACTIVE, &vd_initialize_list);
@@ -7521,7 +7527,7 @@ spa_vdev_split_mirror(spa_t *spa, char *newname, nvlist_t *config,
 	if (error != 0)
 		dmu_tx_abort(tx);
 	for (c = 0; c < children; c++) {
-		if (vml[c] != NULL) {
+		if (vml[c] != NULL && vml[c]->vdev_ops != &vdev_indirect_ops) {
 			vdev_t *tvd = vml[c]->vdev_top;
 
 			/*

module/zfs/vdev_root.c

@@ -98,7 +98,8 @@ vdev_root_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
 	for (int c = 0; c < vd->vdev_children; c++) {
 		vdev_t *cvd = vd->vdev_child[c];
 
-		if (cvd->vdev_open_error && !cvd->vdev_islog) {
+		if (cvd->vdev_open_error && !cvd->vdev_islog &&
+		    cvd->vdev_ops != &vdev_indirect_ops) {
 			lasterror = cvd->vdev_open_error;
 			numerrors++;
 		}

tests/runfiles/common.run

@@ -442,7 +442,7 @@ tags = ['functional', 'cli_root', 'zpool_set']
 [tests/functional/cli_root/zpool_split]
 tests = ['zpool_split_cliargs', 'zpool_split_devices',
     'zpool_split_encryption', 'zpool_split_props', 'zpool_split_vdevs',
-    'zpool_split_resilver']
+    'zpool_split_resilver', 'zpool_split_indirect']
 tags = ['functional', 'cli_root', 'zpool_split']
 
 [tests/functional/cli_root/zpool_status]

tests/zfs-tests/tests/functional/cli_root/zpool_split/Makefile.am

@@ -11,7 +11,8 @@ dist_pkgdata_SCRIPTS = \
 	zpool_split_props.ksh \
 	zpool_split_vdevs.ksh \
 	zpool_split_resilver.ksh \
-	zpool_split_wholedisk.ksh
+	zpool_split_wholedisk.ksh \
+	zpool_split_indirect.ksh
 
 dist_pkgdata_DATA = \
 	zpool_split.cfg

tests/zfs-tests/tests/functional/cli_root/zpool_split/zpool_split_indirect.ksh

@@ -0,0 +1,68 @@
+#!/bin/ksh -p
+#
+# CDDL HEADER START
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2020, George Amanakis. All rights reserved.
+#
+
+. $STF_SUITE/include/libtest.shlib
+. $STF_SUITE/tests/functional/removal/removal.kshlib
+
+#
+# DESCRIPTION:
+#	'zpool split' should succeed on pools with indirect vdevs.
+#
+# STRATEGY:
+#	Create a mirrored pool, add a single device, remove it. `zpool split`
+#	should succeed.
+#
+
+verify_runnable "global"
+
+log_assert "'zpool split' works on pools with indirect VDEVs."
+
+function cleanup
+{
+	if poolexists $TESTPOOL ; then
+		destroy_pool $TESTPOOL
+	fi
+	if poolexists $TESTPOOL2 ; then
+		destroy_pool $TESTPOOL2
+	fi
+	rm -f $VDEV_*
+}
+log_onexit cleanup
+
+typeset vdev_m12_mb=400
+typeset vdev_temp_mb=$(( floor($vdev_m12_mb / 2) ))
+typeset VDEV_TEMP="$TEST_BASE_DIR/vdev_temp"
+typeset VDEV_M1="$TEST_BASE_DIR/vdev_m1"
+typeset VDEV_M2="$TEST_BASE_DIR/vdev_m2"
+typeset altroot="$TESTDIR/altroot-$TESTPOOL2"
+
+log_must truncate -s ${vdev_temp_mb}M $VDEV_TEMP
+log_must truncate -s ${vdev_m12_mb}M $VDEV_M1
+log_must truncate -s ${vdev_m12_mb}M $VDEV_M2
+
+log_must zpool create -f $TESTPOOL $VDEV_TEMP
+log_must zpool add -f $TESTPOOL mirror $VDEV_M1 $VDEV_M2
+log_must zpool remove $TESTPOOL $VDEV_TEMP
+log_must wait_for_removal $TESTPOOL
+log_must zpool split -R $altroot $TESTPOOL $TESTPOOL2
+log_must poolexists $TESTPOOL2
+log_must test "$(get_pool_prop 'altroot' $TESTPOOL2)" == "$altroot"
+
+log_pass "'zpool split' works on pools with indirect VDEVs."