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Re: [lvm-devel] [PATCH] decrease expected_replies when remote node is down [V2]



Dne 31.3.2014 09:54, Dongmao Zhang napsal(a):
> dear list,
> 
> how about this patch?
> 
> any comments there?
> 


Yep - looks like there is a problem but the proposed patch seems to use
unprotected local_client_head list.

Let me think about possibilities we have here.

Zdenek


> 
> 于 2014年02月26日 19:20, dongmao zhang 写道:
>> dear list,
>> I think the last patch is broken, because
>> it has line:thisfd->bits.localsock.finished = 0
>> which may cause pre_post_thread ends.
>> This is the revised patch. So any comments?
>>
>>> when clvmd is waiting for remote node's relies, but
>>> the remote node could be possiblly closed at the same
>>> time. This could result in a request timeout in mainloop.
>>> The default timeout is 60 seconds. This is still too large.
>>>
>>> https://bugzilla.novell.com/show_bug.cgi?id=837538
>>> https://bugzilla.novell.com/show_bug.cgi?id=862633
>>> clvmd users usually meet this when they call LVM command(like vgscan)
>>> in one node, while other nodes's clvmd is closing.
>>>
>>> My solution to this is to decrement in-flight request's
>>> expected_replies. The command could finish much faster in this
>>> situation.
>> ---
>>    daemons/clvmd/clvmd-corosync.c |    7 ++++-
>>    daemons/clvmd/clvmd.c          |   52 +++++++++++++++++++++++++++++++++++++++-
>>    daemons/clvmd/clvmd.h          |    2 +
>>    3 files changed, 59 insertions(+), 2 deletions(-)
>>
>> diff --git a/daemons/clvmd/clvmd-corosync.c b/daemons/clvmd/clvmd-corosync.c
>> index e68cb73..8e642ca 100644
>> --- a/daemons/clvmd/clvmd-corosync.c
>> +++ b/daemons/clvmd/clvmd-corosync.c
>> @@ -251,11 +251,16 @@ static void corosync_cpg_confchg_callback(cpg_handle_t handle,
>>    		ninfo = dm_hash_lookup_binary(node_hash,
>>    					      (char *)&left_list[i].nodeid,
>>    					      COROSYNC_CSID_LEN);
>> -		if (ninfo)
>> +		if (ninfo) {
>>    			ninfo->state = NODE_DOWN;
>> +			char name[MAX_CLUSTER_MEMBER_NAME_LEN];
>> +			sprintf(name, "%x", ninfo->nodeid);
>> +			decrease_inflight_expected_reply(name);
>> +		}
>>    	}
>>    
>>    	num_nodes = member_list_entries;
>> +
>>    }
>>    
>>    static int _init_cluster(void)
>> diff --git a/daemons/clvmd/clvmd.c b/daemons/clvmd/clvmd.c
>> index fc8cf6e..bd056f2 100644
>> --- a/daemons/clvmd/clvmd.c
>> +++ b/daemons/clvmd/clvmd.c
>> @@ -1697,6 +1697,56 @@ static void process_remote_command(struct clvm_header *msg, int msglen, int fd,
>>    	free(replyargs);
>>    }
>>    
>> +void decrease_inflight_expected_reply(char *nodename)
>> +{
>> +	struct local_client * thisfd;
>> +	struct node_reply *reply;
>> +
>> +	DEBUGLOG("remote node %s down", nodename);
>> +
>> +	for (thisfd = &local_client_head; thisfd != NULL;
>> +	     thisfd = thisfd->next) {
>> +		/* in-flight request */
>> +		if (thisfd->type == LOCAL_SOCK
>> +		    && thisfd->bits.localsock.sent_out
>> +		    && thisfd->bits.localsock.in_progress
>> +		    && ! thisfd->bits.localsock.finished
>> +		    && thisfd->bits.localsock.expected_replies >
>> +		    thisfd->bits.localsock.num_replies) {
>> +
>> +			pthread_mutex_lock(&thisfd->bits.localsock.reply_mutex);
>> +
>> +			reply = thisfd->bits.localsock.replies;
>> +			while (reply && strcmp(reply->node, nodename) != 0) {
>> +				reply = reply->next;
>> +			}
>> +			/* if the remote down server has replies,do not decrease the expected_replies */
>> +			if (reply)
>> +				continue;
>> +
>> +			thisfd->bits.localsock.expected_replies--;
>> +			DEBUGLOG
>> +			    ("remote node down, decrement the expected replies to (%ld),num_replies(%ld)",
>> +			     thisfd->bits.localsock.expected_replies,
>> +			     thisfd->bits.localsock.num_replies)
>> +
>> +			if (thisfd->bits.localsock.expected_replies <= thisfd->bits.localsock.num_replies) {
>> +				/* tell pre_and_post thread to finish */
>> +				if (thisfd->bits.localsock.threadid) {
>> +					thisfd->bits.localsock.all_success = 0;
>> +					pthread_mutex_lock(&thisfd->bits.localsock.mutex);
>> +					thisfd->bits.localsock.state = POST_COMMAND;
>> +					pthread_cond_signal(&thisfd->bits.localsock.cond);
>> +					pthread_mutex_unlock(&thisfd->bits.localsock.mutex);
>> +				}
>> +			}
>> +			pthread_mutex_unlock(&thisfd->bits.localsock.reply_mutex);
>> +
>> +		}
>> +	}
>> +
>> +}
>> +
>>    /* Add a reply to a command to the list of replies for this client.
>>       If we have got a full set then send them to the waiting client down the local
>>       socket */
>> @@ -1738,7 +1788,7 @@ static void add_reply_to_list(struct local_client *client, int status,
>>    		 client->bits.localsock.expected_replies);
>>    
>>    	/* If we have the whole lot then do the post-process */
>> -	if (++client->bits.localsock.num_replies ==
>> +	if (++client->bits.localsock.num_replies >=
>>    	    client->bits.localsock.expected_replies) {
>>    		/* Post-process the command */
>>    		if (client->bits.localsock.threadid) {
>> diff --git a/daemons/clvmd/clvmd.h b/daemons/clvmd/clvmd.h
>> index 0f837dd..52e4e61 100644
>> --- a/daemons/clvmd/clvmd.h
>> +++ b/daemons/clvmd/clvmd.h
>> @@ -112,6 +112,8 @@ extern int do_post_command(struct local_client *client);
>>    extern void cmd_client_cleanup(struct local_client *client);
>>    extern int add_client(struct local_client *new_client);
>>    
>> +
>> +extern void decrease_inflight_expected_reply();
>>    extern void clvmd_cluster_init_completed(void);
>>    extern void process_message(struct local_client *client, char *buf,
>>    			    int len, const char *csid);
>>
> 
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