[Cluster-devel] cluster4 dlm: startup notification for systemd

[Jacek Konieczny <jajcus@jajcus.net>]

Hello,

The two patches:

   [PATCH 1/2] --foreground option added to dlm_controld
   [PATCH 2/2] Startup notification by sd_notify()

add startup notification for the systemd service unit. This way startup
of services depending on DLM can be properly serialized.

Currently dlm_controld forks immediately and the parent exits befor the DLM
subsystem is properly initialized. If clvmd is started next, it will fail
with some cryptic error messages (like 'dlm: no local IP address has been
set'). With the startup notification clvmd startup can be delayed until
dlm_controld reports it is ready.

Similar thing could be implemented with forking and no external dependency, ?
but that is a bit more complicated, as requires communication between the
parent and child process or moving the initialization code before fork().

sd_notify() could also be used to provide status information during the
start-up phase too, but I am not familiar enough with what is happening there
to provide reasonable status messages.

Greets,
	Jacek