jiangyiwen
2015-Dec-09 10:19 UTC
[Ocfs2-devel] [PATCH] ocfs2/dlm: wait until DLM_LOCK_RES_SETREF_INPROG is cleared in dlm_deref_lockres_worker
commit f3f854648de6("ocfs2_dlm: Ensure correct ordering of set/clear
refmap bit on lockres") still exists a race which can't ensure the
ordering is exactly correct.
Node1 Node2 Node3
umount, migrate
lockres to Node2
migrate finished,
send migrate request
to Node3
received migrate request,
create a migration_mle,
respond to Node2.
set DLM_LOCK_RES_SETREF_INPROG
and send assert master to
Node3
delete migration_mle in
assert_master_handler,
Node3 umount without response
dlm_thread purge
this lockres, send drop
deref message to Node2
found the flag of
DLM_LOCK_RES_SETREF_INPROG
is set, dispatch
dlm_deref_lockres_worker to
clear refmap, but in function of
dlm_deref_lockres_worker,
only if node in refmap it wait
DLM_LOCK_RES_SETREF_INPROG
to be cleared. So worker is
done successfully
purge lockres, send
assert master response
to Node1, and finish umount
set Node3 in refmap, and it
won't be cleared forever, thus
lead to umount hung
so wait until DLM_LOCK_RES_SETREF_INPROG is cleared in
dlm_deref_lockres_worker.
Signed-off-by: Yiwen Jiang <jiangyiwen at huawei.com>
Reviewed-by: Joseph Qi <joseph.qi at huawei.com>
---
fs/ocfs2/dlm/dlmmaster.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index ce38b4c..666ea67 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -2388,8 +2388,8 @@ static void dlm_deref_lockres_worker(struct dlm_work_item
*item, void *data)
spin_lock(&res->spinlock);
BUG_ON(res->state & DLM_LOCK_RES_DROPPING_REF);
+ __dlm_wait_on_lockres_flags(res, DLM_LOCK_RES_SETREF_INPROG);
if (test_bit(node, res->refmap)) {
- __dlm_wait_on_lockres_flags(res, DLM_LOCK_RES_SETREF_INPROG);
dlm_lockres_clear_refmap_bit(dlm, res, node);
cleared = 1;
}
--
1.8.4.3
Junxiao Bi
2015-Dec-14 05:49 UTC
[Ocfs2-devel] [PATCH] ocfs2/dlm: wait until DLM_LOCK_RES_SETREF_INPROG is cleared in dlm_deref_lockres_worker
On 12/09/2015 06:19 PM, jiangyiwen wrote:> commit f3f854648de6("ocfs2_dlm: Ensure correct ordering of set/clear > refmap bit on lockres") still exists a race which can't ensure the > ordering is exactly correct. > > Node1 Node2 Node3 > umount, migrate > lockres to Node2 > migrate finished, > send migrate request > to Node3 > received migrate request, > create a migration_mle, > respond to Node2. > set DLM_LOCK_RES_SETREF_INPROG > and send assert master to > Node3 > delete migration_mle in > assert_master_handler, > Node3 umount without response > dlm_thread purge > this lockres, send drop > deref message to Node2 > found the flag of > DLM_LOCK_RES_SETREF_INPROG > is set, dispatch > dlm_deref_lockres_worker to > clear refmap, but in function of > dlm_deref_lockres_worker, > only if node in refmap it wait > DLM_LOCK_RES_SETREF_INPROG > to be cleared. So worker is > done successfully > > purge lockres, send > assert master response > to Node1, and finish umount > set Node3 in refmap, and it > won't be cleared forever, thus > lead to umount hung > > so wait until DLM_LOCK_RES_SETREF_INPROG is cleared in > dlm_deref_lockres_worker. > > Signed-off-by: Yiwen Jiang <jiangyiwen at huawei.com> > Reviewed-by: Joseph Qi <joseph.qi at huawei.com>Looks good. Reviewed-by: Junxiao Bi <junxiao.bi at oracle.com>> --- > fs/ocfs2/dlm/dlmmaster.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c > index ce38b4c..666ea67 100644 > --- a/fs/ocfs2/dlm/dlmmaster.c > +++ b/fs/ocfs2/dlm/dlmmaster.c > @@ -2388,8 +2388,8 @@ static void dlm_deref_lockres_worker(struct dlm_work_item *item, void *data) > > spin_lock(&res->spinlock); > BUG_ON(res->state & DLM_LOCK_RES_DROPPING_REF); > + __dlm_wait_on_lockres_flags(res, DLM_LOCK_RES_SETREF_INPROG); > if (test_bit(node, res->refmap)) { > - __dlm_wait_on_lockres_flags(res, DLM_LOCK_RES_SETREF_INPROG); > dlm_lockres_clear_refmap_bit(dlm, res, node); > cleared = 1; > } >