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ocfs2: fix deadlock between o2hb thread and o2net_wq 

The following case may lead to o2net_wq and o2hb thread deadlock on
o2hb_callback_sem.
Currently there are 2 nodes say N1, N2 in the cluster. And N2 down, at
the same time, N3 tries to join the cluster. So N1 will handle node
down (N2) and join (N3) simultaneously.
    o2hb                               o2net_wq
    ->o2hb_do_disk_heartbeat
    ->o2hb_check_slot
    ->o2hb_run_event_list
    ->o2hb_fire_callbacks
    ->down_write(&o2hb_callback_sem)
    ->o2net_hb_node_down_cb
    ->flush_workqueue(o2net_wq)
                                       ->o2net_process_message
                                       ->dlm_query_join_handler
                                       ->o2hb_check_node_heartbeating
                                       ->o2hb_fill_node_map
                                       ->down_read(&o2hb_callback_sem)

No need to take o2hb_callback_sem in dlm_query_join_handler,
o2hb_live_lock is enough to protect live node map.

Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Cc: xMark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: jiangyiwen <jiangyiwen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Joseph Qi 2014-10-09 15:25:13 -07:00 committed by Linus Torvalds
parent 5046f18d5b
commit 70e82a12db
3 changed files with 21 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
fs/ocfs2/cluster/heartbeat.c
View File

@ -2572,6 +2572,25 @@ int o2hb_check_node_heartbeating(u8 node_num)
}
EXPORT_SYMBOL_GPL(o2hb_check_node_heartbeating);
int o2hb_check_node_heartbeating_no_sem(u8 node_num)
{
unsigned long testing_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
unsigned long flags;
spin_lock_irqsave(&o2hb_live_lock, flags);
o2hb_fill_node_map_from_callback(testing_map, sizeof(testing_map));
spin_unlock_irqrestore(&o2hb_live_lock, flags);
if (!test_bit(node_num, testing_map)) {
mlog(ML_HEARTBEAT,
"node (%u) does not have heartbeating enabled.\n",
node_num);
return 0;
}
return 1;
}
EXPORT_SYMBOL_GPL(o2hb_check_node_heartbeating_no_sem);
int o2hb_check_node_heartbeating_from_callback(u8 node_num)
{
unsigned long testing_map[BITS_TO_LONGS(O2NM_MAX_NODES)];

1
fs/ocfs2/cluster/heartbeat.h
View File

@ -80,6 +80,7 @@ void o2hb_fill_node_map(unsigned long *map,
void o2hb_exit(void);
int o2hb_init(void);
int o2hb_check_node_heartbeating(u8 node_num);
int o2hb_check_node_heartbeating_no_sem(u8 node_num);
int o2hb_check_node_heartbeating_from_callback(u8 node_num);
int o2hb_check_local_node_heartbeating(void);
void o2hb_stop_all_regions(void);

2
fs/ocfs2/dlm/dlmdomain.c
View File

@ -839,7 +839,7 @@ static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data,
* to back off and try again. This gives heartbeat a chance
* to catch up.
*/
if (!o2hb_check_node_heartbeating(query->node_idx)) {
if (!o2hb_check_node_heartbeating_no_sem(query->node_idx)) {
mlog(0, "node %u is not in our live map yet\n",
query->node_idx);