dlm: drop dlm_scand kthread and use timers

Currently the scand kthread acts like a garbage collection for expired
rsbs on toss list, to clean them up after a certain timeout. It triggers
every couple of seconds and iterates over the toss list while holding
ls_rsbtbl_lock for the whole hash bucket iteration.

To reduce the amount of time holding ls_rsbtbl_lock, we now handle the
disposal of expired rsbs using a per-lockspace timer that expires for the
earliest tossed rsb on the lockspace toss queue. This toss queue is
ordered according to the rsb res_toss_time with the earliest tossed rsb
as the first entry. The toss timer will only trylock() necessary locks,
since it is low priority garbage collection, and will rearm the timer
if trylock() fails. If the timer function does not find any expired
rsb's, it rearms the timer with the next earliest expired rsb.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/dlm/lock.h b/fs/dlm/lock.h
index b56a34802762..8de9dee4c058 100644
--- a/fs/dlm/lock.h
+++ b/fs/dlm/lock.h
@@ -11,6 +11,7 @@
 #ifndef __LOCK_DOT_H__
 #define __LOCK_DOT_H__
 
+void dlm_rsb_toss_timer(struct timer_list *timer);
 void dlm_dump_rsb(struct dlm_rsb *r);
 void dlm_dump_rsb_name(struct dlm_ls *ls, const char *name, int len);
 void dlm_print_lkb(struct dlm_lkb *lkb);
@@ -26,6 +27,7 @@ void dlm_scan_rsbs(struct dlm_ls *ls);
 int dlm_lock_recovery_try(struct dlm_ls *ls);
 void dlm_lock_recovery(struct dlm_ls *ls);
 void dlm_unlock_recovery(struct dlm_ls *ls);
+void dlm_timer_resume(struct dlm_ls *ls);
 
 int dlm_master_lookup(struct dlm_ls *ls, int from_nodeid, const char *name,
 		      int len, unsigned int flags, int *r_nodeid, int *result);