Hello Mark,
On 2016-7-29 6:12, Mark Fasheh wrote:
> On Thu, Jul 28, 2016 at 02:06:05PM -0700, Andrew Morton wrote:
>> From: piaojun <piao...@huawei.com>
>> Subject: ocfs2/dlm: solve a BUG when deref failed in dlm_drop_lockres_ref
>>
>> We found a BUG situation that lockres is migrated during deref described
>> below. To solve the BUG, we could purge lockres directly when other node
>> says I did not have a ref. Additionally, we'd better purge lockres if
>> master goes down, as no one will response deref done.
>>
>> Node 1 Node 2(old master) Node3(new master)
>> dlm_purge_lockres
>> send deref to N2
>>
>> leave domain
>> migrate lockres to N3
>> finish migration
>> send do assert
>> master to N1
>>
>> receive do assert msg
>> form N3, but can not
>> find lockres because
>> DROPPING_REF is set,
>> so the owner is still
>> N2.
>>
>> receive deref from N1
>> and response -EINVAL
>> because lockres is migrated
>>
>> BUG when receive -EINVAL
>> in dlm_drop_lockres_ref
>>
>> Fixes: 842b90b62461d ("ocfs2/dlm: return in progress if master can not clear
>> the refmap bit right now")
>>
>> Link: http://lkml.kernel.org/r/57845103.3070...@huawei.com
>> Signed-off-by: Jun Piao <piao...@huawei.com>
>> Reviewed-by: Joseph Qi <joseph...@huawei.com>
>> Reviewed-by: Jiufei Xue <xuejiu...@huawei.com>
>
> Reviewed-by: Mark Fasheh <mfas...@suse.de>
>
> The only thing is I wonder if those ML_NOTICE messages in this patch and
> the previous one will cause unnecessary end-user concern.
>
> The fixes though look good, thanks for those.
> --Mark
>
>
Those ML_NOTICE log just server as reminders for developer, I think
end-user usually care about ML_NOTICE log.
Thanks
Jun
>> Cc: Mark Fasheh <mfas...@suse.de>
>> Cc: Joel Becker <jl...@evilplan.org>
>> Cc: Junxiao Bi <junxiao...@oracle.com>
>> Signed-off-by: Andrew Morton <a...@linux-foundation.org>
>> ---
>>
>> fs/ocfs2/dlm/dlmmaster.c | 9 ++++++---
>> fs/ocfs2/dlm/dlmthread.c | 13 +++++++++++--
>> 2 files changed, 17 insertions(+), 5 deletions(-)
>>
>> diff -puN
>> fs/ocfs2/dlm/dlmmaster.c~ocfs2-dlm-solve-a-bug-when-deref-failed-in-dlm_drop_lockres_ref
>> fs/ocfs2/dlm/dlmmaster.c
>> ---
>> a/fs/ocfs2/dlm/dlmmaster.c~ocfs2-dlm-solve-a-bug-when-deref-failed-in-dlm_drop_lockres_ref
>> +++ a/fs/ocfs2/dlm/dlmmaster.c
>> @@ -2276,9 +2276,12 @@ int dlm_drop_lockres_ref(struct dlm_ctxt
>> mlog(ML_ERROR, "%s: res %.*s, DEREF to node %u got %d\n",
>> dlm->name, namelen, lockname, res->owner, r);
>> dlm_print_one_lock_resource(res);
>> - BUG();
>> - }
>> - return ret ? ret : r;
>> + if (r == -ENOMEM)
>> + BUG();
>> + } else
>> + ret = r;
>> +
>> + return ret;
>> }
>>
>> int dlm_deref_lockres_handler(struct o2net_msg *msg, u32 len, void *data,
>> diff -puN
>> fs/ocfs2/dlm/dlmthread.c~ocfs2-dlm-solve-a-bug-when-deref-failed-in-dlm_drop_lockres_ref
>> fs/ocfs2/dlm/dlmthread.c
>> ---
>> a/fs/ocfs2/dlm/dlmthread.c~ocfs2-dlm-solve-a-bug-when-deref-failed-in-dlm_drop_lockres_ref
>> +++ a/fs/ocfs2/dlm/dlmthread.c
>> @@ -175,6 +175,15 @@ static void dlm_purge_lockres(struct dlm
>> res->lockname.len, res->lockname.name, master);
>>
>> if (!master) {
>> + if (res->state & DLM_LOCK_RES_DROPPING_REF) {
>> + mlog(ML_NOTICE, "%s: res %.*s already in "
>> + "DLM_LOCK_RES_DROPPING_REF state\n",
>> + dlm->name, res->lockname.len,
>> + res->lockname.name);
>> + spin_unlock(&res->spinlock);
>> + return;
>> + }
>> +
>> res->state |= DLM_LOCK_RES_DROPPING_REF;
>> /* drop spinlock... retake below */
>> spin_unlock(&res->spinlock);
>> @@ -203,8 +212,8 @@ static void dlm_purge_lockres(struct dlm
>> dlm->purge_count--;
>> }
>>
>> - if (!master && ret != 0) {
>> - mlog(0, "%s: deref %.*s in progress or master goes down\n",
>> + if (!master && ret == DLM_DEREF_RESPONSE_INPROG) {
>> + mlog(0, "%s: deref %.*s in progress\n",
>> dlm->name, res->lockname.len, res->lockname.name);
>> spin_unlock(&res->spinlock);
>> return;
>> _
> --
> Mark Fasheh
>
> .
>
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