Ocfs2 devel - Aug 2016 - [PATCH] A bug in the end of DLM recovery

Hi,

I found an issue in the end of DLM recovery.
When DLM recovery comes to the end of recovery procedure, it will remaster all
locks in other nodes.
Right after a request message is sent to a node A (say), the new master node
will wait for node A?s response forever.
But node A may die just after receiving the remaster request, not responses to
new master node yet.
That causes new master node waiting forever.
I think below patch can solve this problem. Please have a review!


Subject: [PATCH] interrupt waiting for node's response if node dies

Signed-off-by: gechangwei <ge.changwei at h3c.com>
---
dlm/dlmrecovery.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/dlm/dlmrecovery.c b/dlm/dlmrecovery.c
index 3d90ad7..5e455cb 100644
--- a/dlm/dlmrecovery.c
+++ b/dlm/dlmrecovery.c
@@ -679,6 +679,10 @@ static int dlm_remaster_locks(struct dlm_ctxt *dlm, u8
dead_node)
                                                 dlm->name,
ndata->node_num,
                                                
ndata->state==DLM_RECO_NODE_DATA_RECEIVING ?
                                                 "receiving" :
"requested");
+                                            if (dlm_is_node_dead(dlm,
ndata->node_num)) {
+                                                      mlog(0, "%s: node %u
died after requesting all locks.\n");
+                                                      ndata->state =
DLM_RECO_NODE_DATA_DONE;
+                                            }
                                            all_nodes_done = 0;
                                            break;
                                   case DLM_RECO_NODE_DATA_DONE:
--

BR.

Chauncey


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Hi,

On 08/06/2016 01:58 PM, Gechangwei wrote:
> Hi,
>
> I found an issue in the end of DLM recovery.
What's the detailed steps of reproduction?
> When DLM recovery comes to the end of recovery procedure, it will remaster
all locks in other nodes.
> Right after a request message is sent to a node A (say), the new master
node will wait for node A?s response forever.
> But node A may die just after receiving the remaster request, not responses
to new master node yet.
> That causes new master node waiting forever.
> I think below patch can solve this problem. Please have a review!
Sorry, I cannot understand your problem. Could you give a more specific
description
in the style such as this patch from Piaojun couple days ago:

ocfs2/dlm: disable BUG_ON when DLM_LOCK_RES_DROPPING_REF is cleared before 
dlm_deref_lockres_done_handler

Also, a patch should be for a real bug which can be produced, and a test for
this patch must
also be performed. I'm a little worried because this patch is seemingly
based on assumption.


BTW, the format of your patche isn't formal;-) Please
go through docs below:

[1]
https://github.com/torvalds/linux/blob/master/Documentation/SubmittingPatches
[2] https://github.com/torvalds/linux/blob/master/Documentation/SubmitChecklist

Eric
>
>
> Subject: [PATCH] interrupt waiting for node's response if node dies
>
> Signed-off-by: gechangwei <ge.changwei at h3c.com>
> ---
> dlm/dlmrecovery.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/dlm/dlmrecovery.c b/dlm/dlmrecovery.c
> index 3d90ad7..5e455cb 100644
> --- a/dlm/dlmrecovery.c
> +++ b/dlm/dlmrecovery.c
> @@ -679,6 +679,10 @@ static int dlm_remaster_locks(struct dlm_ctxt *dlm, u8
dead_node)
>                                                  dlm->name,
ndata->node_num,
>                                                 
ndata->state==DLM_RECO_NODE_DATA_RECEIVING ?
>                                                  "receiving" :
"requested");
> +                                            if (dlm_is_node_dead(dlm,
ndata->node_num)) {
> +                                                      mlog(0, "%s:
node %u died after requesting all locks.\n");
> +                                                      ndata->state =
DLM_RECO_NODE_DATA_DONE;
> +                                            }
>                                             all_nodes_done = 0;
>                                             break;
>                                    case DLM_RECO_NODE_DATA_DONE:
> --
>
> BR.
>
> Chauncey
>
>
>
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