piaojun
2017-Nov-02 01:42 UTC
[Ocfs2-devel] [PATCH] ocfs2/dlm: wait for dlm recovery done when migrating all lockres
Hi Changwei, I had tried a solution like yours before, but failed to prevent the race just by 'dlm_state' and the existed variable as 'DLM_CTXT_IN_SHUTDOWN' contains many status. so I think we need introduce a 'migrate_done' to solve that problem. thanks, Jun On 2017/11/1 17:00, Changwei Ge wrote:> Hi Jun, > > On 2017/11/1 16:46, piaojun wrote: >> Hi Changwei, >> >> I do think we need follow the principle that use 'dlm_domain_lock' to >> protect 'dlm_state' as the NOTE says in 'dlm_ctxt': >> /* NOTE: Next three are protected by dlm_domain_lock */ >> >> deadnode won't be cleared from 'dlm->domain_map' if return from >> __dlm_hb_node_down(), and NodeA will retry migrating to NodeB forever >> if only NodeA and NodeB in domain. I suggest more testing needed in >> your solution. > > I agree, however, my patch is just a draft to indicate my comments. > > Perhaps we can figure out a better way to solve this, as your patch > can't clear DLM RECOVERING flag on lock resource. I am not sure if it is > reasonable, I suppose this may violate ocfs2/dlm design philosophy. > > Thanks, > Changwei >if res is marked as DLM RECOVERING, migrating process will wait for recoverying done. and DLM RECOVERING will be cleared after recoverying.>> >> thanks, >> Jun >> >> On 2017/11/1 16:11, Changwei Ge wrote: >>> Hi Jun, >>> >>> Thanks for reviewing. >>> I don't think we have to worry about misusing *dlm_domain_lock* and >>> *dlm::spinlock*. I admit my change may look a little different from most >>> of other code snippets where using these two spin locks. But our purpose >>> is to close the race between __dlm_hb_node_down and >>> dlm_unregister_domain, right? And my change meets that. :-) >>> >>> I suppose we can do it in a flexible way. >>> >>> Thanks, >>> Changwei >>> >>> >>> On 2017/11/1 15:57, piaojun wrote: >>>> Hi Changwei, >>>> >>>> thanks for reviewing, and I think waiting for recoverying done before >>>> migrating seems another solution, but I wonder if new problems will be >>>> invoked as following comments. >>>> >>>> thanks, >>>> Jun >>>> >>>> On 2017/11/1 15:13, Changwei Ge wrote: >>>>> 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? >>>> that is it. >>>>> 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); >>>> I guess there will be misuse of 'dlm->spinlock' and dlm_domain_lock. >>>>> 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; >>>>> + >>>> 'dlm->dlm_state' probably need be to protected by 'dlm_domain_lock'. >>>> and I wander if there is more work to be done when in >>>> 'DLM_CTXT_IN_SHUTDOWN'? >>>>> if (dlm->reco.new_master == idx) { >>>>> mlog(0, "%s: recovery master %d just died\n", >>>>> dlm->name, idx); >>>>> >>>> >>> >>> . >>> >> > > . >
Changwei Ge
2017-Nov-02 01:56 UTC
[Ocfs2-devel] [PATCH] ocfs2/dlm: wait for dlm recovery done when migrating all lockres
On 2017/11/2 9:44, piaojun wrote:> Hi Changwei, > > I had tried a solution like yours before, but failed to prevent the > race just by 'dlm_state' and the existed variable as > 'DLM_CTXT_IN_SHUTDOWN' contains many status. so I think we need > introduce a 'migrate_done' to solve that problem.Hi Jun, Yes, adding a new flag might be a direction, but I still think we need to clear other nodes' lock resources' flag - DLM_LOCK_RES_RECOVERING, which depends on NodeA's dlm recovering progress. Unfortunately, it is interrupted by the newly added flag ::migrate_done in your patch. :-( So no DLM_FINALIZE_RECO_MSG message will be sent out to other nodes, thus DLM_LOCK_RES_RECOVERING can't be cleared. As I know, if DLM_LOCK_RES_RECOVERING is set, all lock and unlock requests will be *hang*. Thanks, Changwei> > thanks, > Jun > > On 2017/11/1 17:00, Changwei Ge wrote: >> Hi Jun, >> >> On 2017/11/1 16:46, piaojun wrote: >>> Hi Changwei, >>> >>> I do think we need follow the principle that use 'dlm_domain_lock' to >>> protect 'dlm_state' as the NOTE says in 'dlm_ctxt': >>> /* NOTE: Next three are protected by dlm_domain_lock */ >>> >>> deadnode won't be cleared from 'dlm->domain_map' if return from >>> __dlm_hb_node_down(), and NodeA will retry migrating to NodeB forever >>> if only NodeA and NodeB in domain. I suggest more testing needed in >>> your solution. >> >> I agree, however, my patch is just a draft to indicate my comments. >> >> Perhaps we can figure out a better way to solve this, as your patch >> can't clear DLM RECOVERING flag on lock resource. I am not sure if it is >> reasonable, I suppose this may violate ocfs2/dlm design philosophy. >> >> Thanks, >> Changwei >> > > if res is marked as DLM RECOVERING, migrating process will wait for > recoverying done. and DLM RECOVERING will be cleared after recoverying. > >>> >>> thanks, >>> Jun >>> >>> On 2017/11/1 16:11, Changwei Ge wrote: >>>> Hi Jun, >>>> >>>> Thanks for reviewing. >>>> I don't think we have to worry about misusing *dlm_domain_lock* and >>>> *dlm::spinlock*. I admit my change may look a little different from most >>>> of other code snippets where using these two spin locks. But our purpose >>>> is to close the race between __dlm_hb_node_down and >>>> dlm_unregister_domain, right? And my change meets that. :-) >>>> >>>> I suppose we can do it in a flexible way. >>>> >>>> Thanks, >>>> Changwei >>>> >>>> >>>> On 2017/11/1 15:57, piaojun wrote: >>>>> Hi Changwei, >>>>> >>>>> thanks for reviewing, and I think waiting for recoverying done before >>>>> migrating seems another solution, but I wonder if new problems will be >>>>> invoked as following comments. >>>>> >>>>> thanks, >>>>> Jun >>>>> >>>>> On 2017/11/1 15:13, Changwei Ge wrote: >>>>>> 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? >>>>> that is it. >>>>>> 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); >>>>> I guess there will be misuse of 'dlm->spinlock' and dlm_domain_lock. >>>>>> 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; >>>>>> + >>>>> 'dlm->dlm_state' probably need be to protected by 'dlm_domain_lock'. >>>>> and I wander if there is more work to be done when in >>>>> 'DLM_CTXT_IN_SHUTDOWN'? >>>>>> if (dlm->reco.new_master == idx) { >>>>>> mlog(0, "%s: recovery master %d just died\n", >>>>>> dlm->name, idx); >>>>>> >>>>> >>>> >>>> . >>>> >>> >> >> . >> >