Bug#792002: lvm2-monitor service causes long delay at boot (encrypted root/swap)

[Josh Triplett]

Package: lvm2
Version: 2.02.122-1
Severity: grave
File: /lib/systemd/system/lvm2-monitor.service

On a laptop with encrypted root and swap, I now get a minutes-long delay at boot
time, due to lvm2-monitor.  Here's the complete set of messages at boot
(transcribed from a photo of the screen):

Loading, please wait...
  /run/lvm/lvmetad.socket: connect failed: No such file or directory
  WARNING: Failed to connect to lvmetad. Falling back to internal scanning.
  Volume group "data" not found
  Cannot process volume group data
Unable to find LVM volume data/root
  /run/lvm/lvmetad.socket: connect failed: No such file or directory
  WARNING: Failed to connect to lvmetad. Falling back to internal scanning.
  Volume group "data" not found
  Cannot process volume group data
Unable to find LVM volume data/swap
Please unlock disk sda2_crypt:
  /run/lvm/lvmetad.socket: connect failed: No such file or directory
  WARNING: Failed to connect to lvmetad. Falling back to internal scanning.
  Reading all physical volumes.  This may take a while...
  Found volume group "data" using metadata type lvm2
  /run/lvm/lvmetad.socket: connect failed: No such file or directory
  WARNING: Failed to connect to lvmetad. Falling back to internal scanning.
  2 logical volume(s) in volume group "data" now active
cryptsetup: sda2_crypt set up successfully
fsck from util-linux 2.26.2
/dev/mapper/data-root: clean, [...]
[      ] A start job is running for Monitoring of LVM2 mirrors, snapshots etc. using dmeventd or progress polling (59s / no limit)


That last line matches the description in lvm2-monitor.service.

(The preceeding lvm2 errors may or may not be related.  The recurring
two lines of lvmetad errors are new, as is the long delay on
lvm2-monitor.service; the errors before unlocking the disk about not
finding data/root and data/swap occurred with previous versions of
lvm2.)

- Josh Triplett

-- System Information:
Debian Release: stretch/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.0.0-2-amd64 (SMP w/4 CPU cores)
Locale: LANG=C.UTF-8, LC_CTYPE=C.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                  2:1.02.99-1
ii  dmsetup                   2:1.02.99-1
ii  init-system-helpers       1.23
ii  initscripts               2.88dsf-59.2
ii  libc6                     2.19-18
ii  libdevmapper-event1.02.1  2:1.02.99-1
ii  libdevmapper1.02.1        2:1.02.99-1
ii  libreadline5              5.2+dfsg-3
ii  libudev1                  222-1
ii  lsb-base                  4.1+Debian13+nmu1

lvm2 recommends no packages.

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

-- no debconf information