[Ocfs2-devel] [PATCH 1/7] Add dlm operations placeholders

[Goldwyn Rodrigues <rgoldwyn@suse.de>]

On 09/27/2013 01:59 PM, Joel Becker wrote:
> On Fri, Sep 27, 2013 at 12:06:47PM -0500, Goldwyn Rodrigues wrote:
>> Try locking with the new DLM semantics with the dlm operations.
>> If operation fails with EOPNOTSUPP, try the old semantics.
>> This would ensure that filesystems are mounted for those who
>> are upgrading the kernel but not the tools.
>> Users using old tools will be presented with a notice message
>> to upgrade the tools.
>>
>> recover_prep() is called when DLM understands a node is down.
>> recover_slot() is called once all nodes have acknowledged recover_prep and
>> recovery can begin.
>> recover_done() is called once the recovery is complete. It returns the
>> new membership.
>
> 	Can recover_prep() pause?

 From a locking/lockdep POV yes. However, you want to recover from a 
node failure soon, so not recommended.

 > What does the cluster do when not all nodes acknowledge the prep?

New membership.

> When they die during recover_slot()?

New membership.

> Which node recovers the slot?
recover_slot() and recover_done() is called on all nodes because it also 
has to relay the failing node and the new membership. So, any node can 
perform the recovery.

With this patch series, it is working just as it would before: All nodes 
call recovery. the one who locks the journal first performs the recovery.



>> ---
>>   fs/ocfs2/stack_user.c | 70 +++++++++++++++++++++++++++++++++++++--------------
>>   1 file changed, 51 insertions(+), 19 deletions(-)
>>
>> diff --git a/fs/ocfs2/stack_user.c b/fs/ocfs2/stack_user.c
>> index 286edf1..b44490b 100644
>> --- a/fs/ocfs2/stack_user.c
>> +++ b/fs/ocfs2/stack_user.c
>> @@ -799,14 +799,63 @@ static int fs_protocol_compare(struct ocfs2_protocol_version *existing,
>>   	return 0;
>>   }
>>
>> +static void user_recover_prep(void *arg)
>> +{
>> +}
>> +
>> +static void user_recover_slot(void *arg, struct dlm_slot *slot)
>> +{
>> +}
>> +
>> +static void user_recover_done(void *arg, struct dlm_slot *slots,
>> +			      int num_slots, int our_slot,
>> +			      uint32_t generation)
>> +{
>> +}
>> +
>> +const struct dlm_lockspace_ops ocfs2_ls_ops = {
>> +	.recover_prep = user_recover_prep,
>> +	.recover_slot = user_recover_slot,
>> +	.recover_done = user_recover_done,
>> +};
>> +
>> +static int user_cluster_disconnect(struct ocfs2_cluster_connection *conn)
>> +{
>> +	dlm_release_lockspace(conn->cc_lockspace, 2);
>> +	conn->cc_lockspace = NULL;
>> +	ocfs2_live_connection_drop(conn->cc_private);
>> +	conn->cc_private = NULL;
>> +	return 0;
>> +}
>> +
>>   static int user_cluster_connect(struct ocfs2_cluster_connection *conn)
>>   {
>>   	dlm_lockspace_t *fsdlm;
>>   	struct ocfs2_live_connection *uninitialized_var(control);
>> -	int rc = 0;
>> +	int rc = 0, ops_rv;
>>
>>   	BUG_ON(conn == NULL);
>>
>> +	rc = dlm_new_lockspace(conn->cc_name, NULL, DLM_LSFL_FS, DLM_LVB_LEN,
>> +				&ocfs2_ls_ops, conn, &ops_rv, &fsdlm);
>> +
>> +	if (rc)
>> +		goto out;
>> +
>> +	if (!ops_rv) {
>> +		/* DLM lockspace creation with newer new_lockspace successful */
>> +		goto out;
>> +	} else if (ops_rv != -EOPNOTSUPP) {
>> +		rc = ops_rv;
>> +		goto out;
>> +	}
>> +
>> +	conn->cc_lockspace = fsdlm;
>
> This code returns from !ops_rv before setting cc_lockspace, yet tries to
> reference it out in user_cluster_disconnect().  That looks like a
> crashing bug.
>
> Also, it looks like you call the new form of dlm_new_lockspace() before
> the callbacks are even implemented.  If I just apply this patch, the
> code does not work.  Please reorder the patch so that ocfs2 works at
> each patch.
>

Ok.

> Joel
>
>
>> +
>> +	printk(KERN_NOTICE "ocfs2: You seem to be using an older version "
>> +			"of dlm_controld and/or ocfs2-tools. Please consider "
>> +			"upgrading.\n");
>> +
>>   	rc = ocfs2_live_connection_new(conn, &control);
>>   	if (rc)
>>   		goto out;
>> @@ -823,32 +872,15 @@ static int user_cluster_connect(struct ocfs2_cluster_connection *conn)
>>   		       conn->cc_version.pv_major, conn->cc_version.pv_minor,
>>   		       running_proto.pv_major, running_proto.pv_minor);
>>   		rc = -EPROTO;
>> -		ocfs2_live_connection_drop(control);
>> -		goto out;
>> -	}
>> -
>> -	rc = dlm_new_lockspace(conn->cc_name, NULL, DLM_LSFL_FS, DLM_LVB_LEN,
>> -			       NULL, NULL, NULL, &fsdlm);
>> -	if (rc) {
>> -		ocfs2_live_connection_drop(control);
>> +		user_cluster_disconnect(conn);
>>   		goto out;
>>   	}
>>
>>   	conn->cc_private = control;
>> -	conn->cc_lockspace = fsdlm;
>>   out:
>>   	return rc;
>>   }
>>
>> -static int user_cluster_disconnect(struct ocfs2_cluster_connection *conn)
>> -{
>> -	dlm_release_lockspace(conn->cc_lockspace, 2);
>> -	conn->cc_lockspace = NULL;
>> -	ocfs2_live_connection_drop(conn->cc_private);
>> -	conn->cc_private = NULL;
>> -	return 0;
>> -}
>> -
>>   static int user_cluster_this_node(unsigned int *this_node)
>>   {
>>   	int rc;
>> --
>> 1.8.1.4
>>
>>
>> --
>> Goldwyn
>>
>> _______________________________________________
>> Ocfs2-devel mailing list
>> Ocfs2-devel at oss.oracle.com
>> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
>


-- 
Goldwyn