lvmcache in writeback mode gets stuck flushing dirty blocks

[Lakshmi Narasimhan Sundararajan <lns@portworx.com>]

Hi Team,
A very good day to all.

I am using lvmcache in writeback mode. When there are dirty blocks still in the lv, and if needs to be destroyed or flushed, then
It seems to me that there are some conditions under which the dirty data flush gets stuck forever.


As an example:
root at pdc4-sm35:~# lvremove -f pwx0/pool
  367 blocks must still be flushed.
  367 blocks must still be flushed.
  367 blocks must still be flushed.
  367 blocks must still be flushed.
  367 blocks must still be flushed.
  367 blocks must still be flushed.
^C
root at pdc4-sm35:~#

I am running these version:
root at pdc4-sm35:~# lvm version
  LVM version:     2.02.133(2) (2015-10-30)
  Library version: 1.02.110 (2015-10-30)
  Driver version:  4.34.0
root at pdc4-sm35:~#


This issue seems old and reported multiple places. There have been some acknowledgement that this issue is resolved in 2.02.133, but still I see it. Also, I have seen some posts report it in 2.02.170+ as well (here: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=878441) (Package: lvm2 Version: 2.02.173-1 Severity: normal)

I filed one here myself, https://github.com/lvmteam/lvm2/issues/22, trying  to understand from you experts where we are on this?

I would sincerely appreciate your help in understanding the state of this issue in more detail.

Best regards
LN
Sent from Mail for Windows 10

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