Comment # 2 on bug 1006952 from GuoQing Jiang

I tried with following cmds, seems it can't be reproduced from my side.

linux-3joh:~ # pvs
  PV         VG  Fmt  Attr PSize   PFree  
  /dev/loop1 vg1 lvm2 a--  996.00m 996.00m
  /dev/loop2 vg1 lvm2 a--    1.46g   1.46g
linux-3joh:~ # lvcreate -L 80M -n lvslow vg1 /dev/loop1
  Logical volume "lvslow" created.
linux-3joh:~ # lvcreate -L 40M -n lvfast vg1 /dev/loop2
  Logical volume "lvfast" created.
linux-3joh:~ # lvcreate -L 8M -n lvfastmeta vg1 /dev/loop2
  Logical volume "lvfastmeta" created.

linux-3joh:~ # lvconvert --type cache-pool --poolmetadata vg1/lvfastmeta
--cachemode writethrough vg1/lvfast
  WARNING: Converting logical volume vg1/lvfast and vg1/lvfastmeta to cache
pool's data and metadata volumes with metadata wiping.
  THIS WILL DESTROY CONTENT OF LOGICAL VOLUME (filesystem etc.)
Do you really want to convert vg1/lvfast and vg1/lvfastmeta? [y/n]: y
  Converted vg1/lvfast to cache pool.

linux-3joh:~ # lvs -o +cache_mode
  LV     VG  Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync
Convert CacheMode   
  lvfast vg1 Cwi---C--- 40.00m                                                 
   writethrough
  lvslow vg1 -wi-a----- 80.00m

linux-3joh:~ # uname -r
4.8.7-1-default
linux-3joh:~ # cat /etc/issue
Welcome to openSUSE Tumbleweed 20161116 - Kernel \r (\l).


Could you pls elaborated your steps? Thanks.