[Bug 1657646] Re: [20.04] Missing thin-provisioning-tools prevents VG with thin pool LV from being (de)activated, but not its creation

[Christian Ehrhardt ]

The MIR itself (bug 1828887) also got no update.

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Title:
  [20.04] Missing thin-provisioning-tools prevents VG with thin pool LV
  from being (de)activated, but not its creation

Status in The Ubuntu-power-systems project:
  Triaged
Status in lvm2 package in Ubuntu:
  Fix Released
Status in lvm2 package in Debian:
  New

Bug description:
  Creating a thin pool LV is allowed even when thin-provisioning-tools
  is not installed. But deactivating or activating that VG fails. Since
  deactivating the VG usually only happens at reboot, the user might
  fail to notice this big problem until then.

  I think the lvconvert tool, used to combine the two "thin LVs" into a
  thin pool LV, should refuse to run if thin-provisioning-tools, or the
  needed scripts, aren't installed.

  Steps to reproduce:
  root at 15-89:~# vgcreate vg /dev/vdb1
    Volume group "vg" successfully created

  root at 15-89:~# vgs
    VG   #PV #LV #SN Attr   VSize  VFree
    vg     1   0   0 wz--n- 40.00g 40.00g

  root at 15-89:~# lvcreate -n pool0 -l 90%VG vg
    Logical volume "pool0" created.

  root at 15-89:~# lvcreate -n pool0meta -l 5%VG vg
    Logical volume "pool0meta" created.

  root at 15-89:~# lvs
    LV        VG   Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
    pool0     vg   -wi-a----- 36.00g
    pool0meta vg   -wi-a-----  2.00g

  root at 15-89:~# ll /dev/mapper/
  total 0
  drwxr-xr-x  2 root root     100 Jun 21 14:15 ./
  drwxr-xr-x 20 root root    3820 Jun 21 14:15 ../
  crw-------  1 root root 10, 236 Jun 21 13:15 control
  lrwxrwxrwx  1 root root       7 Jun 21 14:14 vg-pool0 -> ../dm-0
  lrwxrwxrwx  1 root root       7 Jun 21 14:15 vg-pool0meta -> ../dm-1

  root at 15-89:~# lvconvert --type thin-pool --poolmetadata vg/pool0meta vg/pool0
    WARNING: Converting logical volume vg/pool0 and vg/pool0meta to pool's data and metadata volumes.
    THIS WILL DESTROY CONTENT OF LOGICAL VOLUME (filesystem etc.)
  Do you really want to convert vg/pool0 and vg/pool0meta? [y/n]: y
    Converted vg/pool0 to thin pool.

  root at 15-89:~# ll /dev/mapper/
  total 0
  drwxr-xr-x  2 root root     120 Jun 21 14:15 ./
  drwxr-xr-x 20 root root    3840 Jun 21 14:15 ../
  crw-------  1 root root 10, 236 Jun 21 13:15 control
  lrwxrwxrwx  1 root root       7 Jun 21 14:15 vg-pool0 -> ../dm-2
  lrwxrwxrwx  1 root root       7 Jun 21 14:15 vg-pool0_tdata -> ../dm-1
  lrwxrwxrwx  1 root root       7 Jun 21 14:15 vg-pool0_tmeta -> ../dm-0
  root at 15-89:~# lvs -a
    LV              VG   Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%S
  ync Convert
    [lvol0_pmspare] vg   ewi-------  2.00g
    pool0           vg   twi-a-tz-- 36.00g             0.00   0.01
    [pool0_tdata]   vg   Twi-ao---- 36.00g
    [pool0_tmeta]   vg   ewi-ao----  2.00g

  If you now reboot the system, all that is gone:
  root at 15-89:~# ll /dev/mapper/
  total 0
  drwxr-xr-x  2 root root      60 Jun 21 14:28 ./
  drwxr-xr-x 19 root root    3760 Jun 21 14:28 ../
  crw-------  1 root root 10, 236 Jun 21 14:28 control

  The same happens if you deactivate the VG (which the reboot
  undoubtedly triggers). It fails because of a missing
  /usr/sbin/thin_check which is provided by the thin-provisioning-tools
  package:

  root at 15-89:~# vgchange -a n
    /usr/sbin/thin_check: execvp failed: No such file or directory
    WARNING: Integrity check of metadata for pool vg/pool0 failed.
    0 logical volume(s) in volume group "vg" now active

  root at 15-89:~# ll /dev/mapper/
  total 0
  drwxr-xr-x  2 root root      60 Jun 21 14:29 ./
  drwxr-xr-x 19 root root    3760 Jun 21 14:29 ../
  crw-------  1 root root 10, 236 Jun 21 14:28 control

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