writecache: enable use with thin pool data

. it's of little use since the thin pool cannot be extended
  while it's using writecache.

. lvconvert --splitcache on tdata isn't working, the writecache
  table doesn't get updated with the cleaner setting.

. adding writecache to existing tdata not yet implemented

test/shell/writecache-thin.sh

@@ -0,0 +1,198 @@
+#!/usr/bin/env bash
+
+# Copyright (C) 2018 Red Hat, Inc. All rights reserved.
+#
+# This copyrighted material is made available to anyone wishing to use,
+# modify, copy, or redistribute it subject to the terms and conditions
+# of the GNU General Public License v.2.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+
+SKIP_WITH_LVMPOLLD=1
+
+. lib/inittest
+
+mkfs_mount_unmount()
+{
+        lvt=$1
+
+        mkfs.xfs -f "$DM_DEV_DIR/$vg/$lvt"
+        mount "$DM_DEV_DIR/$vg/$lvt" "$mount_dir"
+        cp pattern1 "$mount_dir/pattern1"
+        umount "$mount_dir"
+}
+
+setup_thin_lvs()
+{
+	pool=$1
+
+	for i in $(seq 1 4); do
+		lvcreate --type thin -V1G -n th$i --thinpool $pool $vg
+		mkfs_mount_unmount th${i}
+		lvchange -an $vg/th${i}
+	done
+}
+
+diff_thin_lvs()
+{
+	for i in $(seq 1 4); do
+        	diff pattern1 "${mount_dir}_${i}/pattern1"
+        	diff pattern2 "${mount_dir}_${i}/pattern2"
+	done
+}
+
+mount_thin_lvs()
+{
+	for i in $(seq 1 4); do
+		lvchange -ay $vg/th$i
+		mount "$DM_DEV_DIR/$vg/th$i" "${mount_dir}_${i}"
+	done
+}
+
+unmount_thin_lvs()
+{
+	for i in $(seq 1 4); do
+		umount "${mount_dir}_${i}"
+		lvchange -an $vg/th${i}
+	done
+}
+
+write_thin_lvs()
+{
+	for i in $(seq 1 4); do
+        	cp pattern2 "${mount_dir}_${i}/pattern2"
+	done
+}
+
+aux have_writecache 1 0 0 || skip
+which mkfs.xfs || skip
+
+mount_dir="mnt"
+mount_dir_1="mnt1"
+mount_dir_2="mnt2"
+mount_dir_3="mnt3"
+mount_dir_4="mnt4"
+mkdir -p "$mount_dir"
+for i in $(seq 1 4); do
+	mkdir -p "${mount_dir}_${i}"
+done
+
+# generate random data
+dd if=/dev/urandom of=pattern1 bs=512K count=1
+dd if=/dev/urandom of=pattern2 bs=512 count=15
+
+aux prepare_devs 6 40
+
+vgcreate $SHARED $vg "$dev1" "$dev2" "$dev3" "$dev4" "$dev5" "$dev6"
+
+#
+# writecache as thin pool data
+# splitcache while inactive
+#
+
+# lv1 holds thin pool data and uses writecache
+# lv2 holds cachevol for writecache
+# lv3 holds thin pool metadata
+lvcreate -n $lv1 -l 16 -an $vg "$dev1" "$dev2"
+lvcreate -n $lv2 -l 2 -an $vg "$dev3"
+lvcreate -n $lv3 -l 2 -an $vg "$dev4"
+lvconvert -y --type writecache --cachevol $lv2 $vg/$lv1
+lvconvert -y --type thin-pool --poolmetadata $lv3 --poolmetadataspare n $vg/$lv1
+
+setup_thin_lvs $lv1
+mount_thin_lvs
+write_thin_lvs
+unmount_thin_lvs
+
+lvchange -an $vg/$lv1
+lvconvert --splitcache --cachesettings cleaner=0 $vg/${lv1}_tdata
+lvs -o segtype $vg/$lv2 | grep linear
+
+mount_thin_lvs
+diff_thin_lvs
+unmount_thin_lvs
+
+lvremove -y $vg/$lv1
+lvremove -y $vg/$lv2
+
+#
+# writecache as thin pool data
+# splitcache while active
+#
+
+# lv1 holds thin pool data and uses writecache
+# lv2 holds cachevol for writecache
+# lv3 holds thin pool metadata
+lvcreate -n $lv1 -l 16 -an $vg "$dev1" "$dev2"
+lvcreate -n $lv2 -l 2 -an $vg "$dev3"
+lvcreate -n $lv3 -l 2 -an $vg "$dev4"
+lvconvert -y --type writecache --cachevol $lv2 $vg/$lv1
+lvconvert -y --type thin-pool --poolmetadata $lv3 --poolmetadataspare n $vg/$lv1
+
+setup_thin_lvs $lv1
+mount_thin_lvs
+write_thin_lvs
+
+# FIXME: splitcache setting cleaner on tdata writecache doesn't work,
+# bypassing that with cleaner=0 here.
+
+lvconvert --splitcache --cachesettings cleaner=0 $vg/${lv1}_tdata
+lvs -o segtype $vg/$lv2 | grep linear
+
+diff_thin_lvs
+unmount_thin_lvs
+
+mount_thin_lvs
+diff_thin_lvs
+unmount_thin_lvs
+
+lvremove -y $vg/$lv1
+lvremove -y $vg/$lv2
+
+
+#
+# add writecache to raid, then use writecache for thin pool data
+#
+
+# lv1 holds thin pool data and uses writecache
+# lv2 holds cachevol for writecache
+# lv3 holds thin pool metadata
+lvcreate --type raid1 -m1 -n $lv1 -l 16 -an $vg "$dev1" "$dev2" "$dev5" "$dev6"
+lvcreate -n $lv2 -l 2 -an $vg "$dev3"
+lvcreate -n $lv3 -l 2 -an $vg "$dev4"
+lvconvert -y --type writecache --cachevol $lv2 $vg/$lv1
+lvconvert -y --type thin-pool --poolmetadata $lv3 --poolmetadataspare n $vg/$lv1
+
+setup_thin_lvs $lv1
+mount_thin_lvs
+write_thin_lvs
+
+lvconvert --splitcache --cachesettings cleaner=0 $vg/${lv1}_tdata
+lvs -o segtype $vg/$lv2 | grep linear
+
+diff_thin_lvs
+unmount_thin_lvs
+
+mount_thin_lvs
+diff_thin_lvs
+unmount_thin_lvs
+
+lvremove -y $vg/$lv1
+lvremove -y $vg/$lv2
+
+
+#
+# remove writecache from thin pool data when cachevol is missing
+#
+
+#
+# FIXME: add writecache to existing thin pool data
+#
+
+#
+# FIXME: thin pool data cannot be extended when it uses writecache
+#
+
+vgremove -ff $vg

tools/command-lines.in

@@ -512,7 +512,7 @@ RULE: all and lv_is_visible
 
 ---
 
-lvconvert --type thin-pool LV_linear_striped_raid_cache
+lvconvert --type thin-pool LV_linear_striped_raid_cache_writecache
 OO: --stripes_long Number, --stripesize SizeKB,
 --discards Discards, OO_LVCONVERT_POOL, OO_LVCONVERT
 OP: PV ...