Bug#857142: lvm2: cache-pool un-checkable after crash because cache_check is not present

[Benjamin Cama]

Package: lvm2
Version: 2.02.111-2.2+deb8u1
Severity: important

Dear Maintainer,

I recently added a cache LV to cache my home LV, and had not rebooted
much since. After a kernel crash, I hard-rebooted but the system led me
into a recovery shell because my home LV could not be activated. When
trying to activate it, it gave:

  /usr/sbin/cache_check: execvp failed: Aucun fichier ou dossier de ce type
  Check of pool main/ssd-cache failed (status:2). Manual repair required!

(first message is “no such file or directory” in french). The cache
seemed corrupt, and indeed, cache_check is not present, and AFAIK not
present anywhere in the Debian repository (I searched in latest sid
packages). LVM sources tell me that it comes from
https://github.com/jthornber/thin-provisioning-tools and I was able to
check the cache and activate my home LV after compiling and running this
tool.

Still, as cache LVs seem activated and “supported” by Debian since 111,
it seems difficult not to distribute this tool. The configuration
example even says that it is executed each time a cached volume is
activated (I think I never rebooted normally once since activating it,
so I cannot confirm), but it looks quite necessary to make this feature
usable.

Could you try to include this tool in Debian, or at least give a big
warning that cache-pools are dangerous without it? Thanks.

-- System Information:
Debian Release: 8.7
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.8.0-0.bpo.2-amd64 (SMP w/4 CPU cores)
Locale: LANG=fr_FR.utf8, LC_CTYPE=fr_FR.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages lvm2 depends on:
ii  dmeventd                  2:1.02.90-2.2+deb8u1
ii  dmsetup                   2:1.02.90-2.2+deb8u1
ii  init-system-helpers       1.22
ii  initscripts               2.88dsf-59
ii  libc6                     2.19-18+deb8u7
ii  libdevmapper-event1.02.1  2:1.02.90-2.2+deb8u1
ii  libdevmapper1.02.1        2:1.02.90-2.2+deb8u1
ii  libreadline5              5.2+dfsg-2
ii  libudev1                  215-17+deb8u6
ii  lsb-base                  4.1+Debian13+nmu1

lvm2 recommends no packages.

Versions of packages lvm2 suggests:
pn  thin-provisioning-tools  <none>

-- no debconf information