[Ocfs2-devel] [PATCH] ocfs2/dlm: wait for dlm recovery done when migrating all lockres
Changwei Ge
ge.changwei at h3c.com
Wed Nov 1 00:13:19 PDT 2017
Hi Jun,
I probably get your point.
You mean that dlm finds no lock resource to be migrated and no more lock
resource is managed by its hash table. After that a node dies all of a
sudden and the dead node is put into dlm's recovery map, right?
Furthermore, a lock resource is migrated from other nodes and local node
has already asserted master to them.
If so, I want to suggest a easier way to solve it.
We don't have to add a new flag to dlm structure, just leverage existed
dlm status and bitmap.
It will bring a bonus - no lock resource will be marked with RECOVERING,
it's a safer way, I suppose.
Please take a review.
Thanks,
Changwei
Subject: [PATCH] ocfs2/dlm: a node can't be involved in recovery if it
is being shutdown
Signed-off-by: Changwei Ge <ge.changwei at h3c.com>
---
fs/ocfs2/dlm/dlmdomain.c | 4 ++++
fs/ocfs2/dlm/dlmrecovery.c | 3 +++
2 files changed, 7 insertions(+)
diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
index a2b19fbdcf46..5e9283e509a4 100644
--- a/fs/ocfs2/dlm/dlmdomain.c
+++ b/fs/ocfs2/dlm/dlmdomain.c
@@ -707,11 +707,15 @@ void dlm_unregister_domain(struct dlm_ctxt *dlm)
* want new domain joins to communicate with us at
* least until we've completed migration of our
* resources. */
+ spin_lock(&dlm->spinlock);
dlm->dlm_state = DLM_CTXT_IN_SHUTDOWN;
+ spin_unlock(&dlm->spinlock);
leave = 1;
}
spin_unlock(&dlm_domain_lock);
+ dlm_wait_for_recovery(dlm);
+
if (leave) {
mlog(0, "shutting down domain %s\n", dlm->name);
dlm_begin_exit_domain(dlm);
diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
index 74407c6dd592..764c95b2b35c 100644
--- a/fs/ocfs2/dlm/dlmrecovery.c
+++ b/fs/ocfs2/dlm/dlmrecovery.c
@@ -2441,6 +2441,9 @@ static void __dlm_hb_node_down(struct dlm_ctxt
*dlm, int idx)
{
assert_spin_locked(&dlm->spinlock);
+ if (dlm->dlm_state == DLM_CTXT_IN_SHUTDOWN)
+ return;
+
if (dlm->reco.new_master == idx) {
mlog(0, "%s: recovery master %d just died\n",
dlm->name, idx);
--
2.11.0
On 2017/11/1 13:53, piaojun wrote:
> Hi Changwei,
>
> On 2017/11/1 10:47, Changwei Ge wrote:
>> Hi Jun,
>>
>> Thanks for reporting.
>> I am very interesting in this issue. But, first of all, I want to make
>> this issue clear, so that I might be able to provide some comments.
>>
>>
>> On 2017/11/1 9:16, piaojun wrote:
>>> wait for dlm recovery done when migrating all lockres in case of new
>>> lockres to be left after leaving dlm domain.
>>
>> What do you mean by 'a new lock resource to be left after leaving
>> domain'? It means we leak a dlm lock resource if below situation happens.
>>
> a new lockres is the one collected by NodeA during recoverying for
> NodeB. It leaks a lockres indeed.
>>>
>>> NodeA NodeB NodeC
>>>
>>> umount and migrate
>>> all lockres
>>>
>>> node down
>>>
>>> do recovery for NodeB
>>> and collect a new lockres
>>> form other live nodes
>>
>> You mean a lock resource whose owner was NodeB is just migrated from
>> other cluster member nodes?
>>
> that is it.
>>>
>>> leave domain but the
>>> new lockres remains
>>>
>>> mount and join domain
>>>
>>> request for the owner
>>> of the new lockres, but
>>> all the other nodes said
>>> 'NO', so NodeC decide to
>>> the owner, and send do
>>> assert msg to other nodes.
>>>
>>> other nodes receive the msg
>>> and found two masters exist.
>>> at last cause BUG in
>>> dlm_assert_master_handler()
>>> -->BUG();
>>
>> If this issue truly exists, can we take some efforts in
>> dlm_exit_domain_handler? Or perhaps we should kick dlm's work queue
>> before migrating all lock resources.
>>
> If NodeA has entered dlm_leave_domain(), we can hardly go back
> migrating res. Perhaps more work will be needed in that way.
>>>
>>> Fixes: bc9838c4d44a ("dlm: allow dlm do recovery during shutdown")
>>>
>>> Signed-off-by: Jun Piao <piaojun at huawei.com>
>>> Reviewed-by: Alex Chen <alex.chen at huawei.com>
>>> Reviewed-by: Yiwen Jiang <jiangyiwen at huawei.com>
>>> ---
>>> fs/ocfs2/dlm/dlmcommon.h | 1 +
>>> fs/ocfs2/dlm/dlmdomain.c | 14 ++++++++++++++
>>> fs/ocfs2/dlm/dlmrecovery.c | 12 +++++++++---
>>> 3 files changed, 24 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/fs/ocfs2/dlm/dlmcommon.h b/fs/ocfs2/dlm/dlmcommon.h
>>> index e9f3705..999ab7d 100644
>>> --- a/fs/ocfs2/dlm/dlmcommon.h
>>> +++ b/fs/ocfs2/dlm/dlmcommon.h
>>> @@ -140,6 +140,7 @@ struct dlm_ctxt
>>> u8 node_num;
>>> u32 key;
>>> u8 joining_node;
>>> + u8 migrate_done; /* set to 1 means node has migrated all lockres */
>>> wait_queue_head_t dlm_join_events;
>>> unsigned long live_nodes_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
>>> unsigned long domain_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
>>> diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
>>> index e1fea14..98a8f56 100644
>>> --- a/fs/ocfs2/dlm/dlmdomain.c
>>> +++ b/fs/ocfs2/dlm/dlmdomain.c
>>> @@ -461,6 +461,18 @@ static int dlm_migrate_all_locks(struct dlm_ctxt *dlm)
>>> cond_resched_lock(&dlm->spinlock);
>>> num += n;
>>> }
>>> +
>>> + if (!num) {
>>> + if (dlm->reco.state & DLM_RECO_STATE_ACTIVE) {
>>> + mlog(0, "%s: perhaps there are more lock resources need to "
>>> + "be migrated after dlm recovery\n", dlm->name);
>>
>> If dlm is mark with DLM_RECO_STATE_ACTIVE, then a lock resource must
>> already be marked with DLM_LOCK_RES_RECOVERING which can't be migrated.
>> So code will goto redo_bucket in function dlm_migrate_all_locks.
>> So I don't understand why a judgement is added here?
>>
>>
>>
> because we have done migrating before recoverying. the judgement here
> is to avoid the following potential recoverying.
>>> + ret = -EAGAIN;
>>> + } else {
>>> + mlog(0, "%s: we won't do dlm recovery after migrating all lockres",
>>> + dlm->name);
>>> + dlm->migrate_done = 1;
>>> + }
>>> + }
>>> spin_unlock(&dlm->spinlock);
>>> wake_up(&dlm->dlm_thread_wq);
>>>
>>> @@ -2052,6 +2064,8 @@ static struct dlm_ctxt *dlm_alloc_ctxt(const char *domain,
>>> dlm->joining_node = DLM_LOCK_RES_OWNER_UNKNOWN;
>>> init_waitqueue_head(&dlm->dlm_join_events);
>>>
>>> + dlm->migrate_done = 0;
>>> +
>>> dlm->reco.new_master = O2NM_INVALID_NODE_NUM;
>>> dlm->reco.dead_node = O2NM_INVALID_NODE_NUM;
>>>
>>> diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
>>> index 74407c6..3106332 100644
>>> --- a/fs/ocfs2/dlm/dlmrecovery.c
>>> +++ b/fs/ocfs2/dlm/dlmrecovery.c
>>> @@ -423,12 +423,11 @@ void dlm_wait_for_recovery(struct dlm_ctxt *dlm)
>>>
>>> static void dlm_begin_recovery(struct dlm_ctxt *dlm)
>>> {
>>> - spin_lock(&dlm->spinlock);
>>> + assert_spin_locked(&dlm->spinlock);
>>> BUG_ON(dlm->reco.state & DLM_RECO_STATE_ACTIVE);
>>> printk(KERN_NOTICE "o2dlm: Begin recovery on domain %s for node %u\n",
>>> dlm->name, dlm->reco.dead_node);
>>> dlm->reco.state |= DLM_RECO_STATE_ACTIVE;
>>> - spin_unlock(&dlm->spinlock);
>>> }
>>>
>>> static void dlm_end_recovery(struct dlm_ctxt *dlm)
>>> @@ -456,6 +455,12 @@ static int dlm_do_recovery(struct dlm_ctxt *dlm)
>>>
>>> spin_lock(&dlm->spinlock);
>>>
>>> + if (dlm->migrate_done) {
>>> + mlog(0, "%s: no need do recovery after migrating all lockres\n",
>>> + dlm->name);
>>
>> Don't we need unlock above spin_lock before return?
>>
>> And if we just return here, how dlm lock resource can clear its
>> REDISCOVERING flag. I suppose this may cause cluster hang.
>>
>> And I cc this to ocfs2 maintainers.
>>
>> Thanks,
>> Changwei
>>
> oh, good catch, I missed spin_unlock(&dlm->spinlock);
>>> + return 0;
>>> + }
>>> +
>>> /* check to see if the new master has died */
>>> if (dlm->reco.new_master != O2NM_INVALID_NODE_NUM &&
>>> test_bit(dlm->reco.new_master, dlm->recovery_map)) {
>>> @@ -490,12 +495,13 @@ static int dlm_do_recovery(struct dlm_ctxt *dlm)
>>> mlog(0, "%s(%d):recovery thread found node %u in the recovery map!\n",
>>> dlm->name, task_pid_nr(dlm->dlm_reco_thread_task),
>>> dlm->reco.dead_node);
>>> - spin_unlock(&dlm->spinlock);
>>>
>>> /* take write barrier */
>>> /* (stops the list reshuffling thread, proxy ast handling) */
>>> dlm_begin_recovery(dlm);
>>>
>>> + spin_unlock(&dlm->spinlock);
>>> +
>>> if (dlm->reco.new_master == dlm->node_num)
>>> goto master_here;
>>>
>>
>> .
>>
>
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