[PATCH 0/3] NLM: Proposal for a timeout setting on blocking locks

[Mikael Davranche <mikael.davranche@free.fr>]

Hi,

When a lock blocks, the server sends us a BLOCKED message. When it releases, it
may sends us an NLM callback. When it does not (it depends on NLM
 implementations), the client waits for 30 seconds before attempting to reclaim
the lock again.

The 30 seconds time is hard-coded on fs/lockd/clntproc.c:
#define NLMCLNT_POLL_TIMEOUT   (30*HZ)

30 seconds is generally suitable, but in some cases, it is too much and it may
be set to less than that. I have this problem in my production env
ironment when an e-mail box receives more than 1 e-mail every 30 seconds. In
that particular case, the nlm_blocked list grows up and never reduce
s. Setting this time to less than 30 seconds resolves the problem.

This short series of patches enables the set of this timeout, setting a new
/proc entry named nlm_clnt_poll_timeout (this name is based on the NL
MCLNT_POLL_TIMEOUT define). Patches are based on the 2.6.24.3 version (is that a
problem? may I base them on the 2.6.25-rc5 one?).

What do you think about this? Any comments are very welcome.

Cheers, Mikael

-- 
Mikael Davranche
System Engineer
Atos Worldline, France