[Cluster-devel] [PATCH 2/3] NLM per-ip grace period - core

Wendy Cheng wcheng at redhat.com
Fri Jan 25 05:17:30 UTC 2008


The logic is implemented on top of linux nfsd procfs with core functions 
residing in lockd kernel module. Entry function is nlmsvc_resume_ip() 
where it stores the requested ip interface into a linked-list 
nlm_failover_list. The list entry count is nlm_failover_cnt and access 
protection is done by nlm_failover_mutex. Entry in nlm_failover_ip_list 
is a "nlm_failover_struct", defined in: include/linux/lockd/lockd.h.

The list is kept in descending order (newer entry first) based on 
g_expire jiffies. For per ip grace period checking, the search goes thru 
the list. As soon as one match ip is found, the search stops. This 
implies older entries will not be used and always expire before new 
entry. This is to allow multiple entries (for the same ip) to be added 
into the list. The maximum size of the list entries is NLM_FO_MAX_GP_CNT 
(1024).

-- Wendy
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