Bug#885660: lvm2: vgchange -ay has a race condition in symlink creation

[Karl O. Pinc]

Package: lvm2
Version: 2.02.168-2
Severity: normal

Hi,

After upgrade from Jessie to Stretch I now see a race condition in
'vgchange -ay'.

I've a shell script that does a 'vgchange -ay' and on success proceeds
to mount the newly active logical volumes.  Now, about 1 in 10 times,
the symlinks in /dev/$VGNAME/$LVNAME (and
/dev/mapper/${VGNAME}-${LVNAME}, I've tried both) do not yet exist
after vgchange exits and the mount commands fail.  Looking at /dev/
afterwards shows the symlinks do exist, hence a race condition.

The workaround I am trying is to sleep 1 second after vgchange.
(This is lame.  Other suggestions would be appreciated. :)

See also Bug#795867.

-- System Information:
Debian Release: 9.3
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.9.0-4-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages lvm2 depends on:
ii  dmeventd                  2:1.02.137-2
ii  dmsetup                   2:1.02.137-2
ii  init-system-helpers       1.48
ii  libblkid1                 2.29.2-1
ii  libc6                     2.24-11+deb9u1
ii  libdevmapper-event1.02.1  2:1.02.137-2
ii  libdevmapper1.02.1        2:1.02.137-2
ii  liblvm2app2.2             2.02.168-2
ii  libreadline5              5.2+dfsg-3+b1
ii  libudev1                  232-25+deb9u1
ii  lsb-base                  9.20161125

lvm2 recommends no packages.

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

-- no debconf information