Ocfs2 devel - May 2017 - [PATCH] ocfs2: give an obvious tip for dismatch cluster names

Hi Gang,

How can we confirm EBADR is only because cluster name mismatch?
Since the cluster stack may be o2cb(o2dlm) or user(fsdlm).

Thanks,
Joseph

On 17/5/18 14:35, Gang He wrote:
> This patch is used to add an obvious error message, due to
> dismatch cluster names between on-disk and in the current cluster.
> We can meet this case during OCFS2 cluster migration, if we can
> give the user an obvious tip for why they can not mount the file
> system after migration, they can quickly fix this dismatch problem.
> Second, also move printing ocfs2_fill_super() errno to the front
> of ocfs2_dismount_volume() function, since ocfs2_dismount_volume()
> will also print it's own message.
> 
> Signed-off-by: Gang He <ghe at suse.com>
> ---
>  fs/ocfs2/super.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
> index ca1646f..5575918 100644
> --- a/fs/ocfs2/super.c
> +++ b/fs/ocfs2/super.c
> @@ -1208,14 +1208,15 @@ static int ocfs2_fill_super(struct super_block *sb,
void *data, int silent)
>  read_super_error:
>  	brelse(bh);
>  
> +	if (status)
> +		mlog_errno(status);
> +
>  	if (osb) {
>  		atomic_set(&osb->vol_state, VOLUME_DISABLED);
>  		wake_up(&osb->osb_mount_event);
>  		ocfs2_dismount_volume(sb, 1);
>  	}
>  
> -	if (status)
> -		mlog_errno(status);
>  	return status;
>  }
>  
> @@ -1843,6 +1844,9 @@ static int ocfs2_mount_volume(struct super_block *sb)
>  	status = ocfs2_dlm_init(osb);
>  	if (status < 0) {
>  		mlog_errno(status);
> +		if (status == -EBADR)
> +			mlog(ML_ERROR, "couldn't mount because cluster name on"
> +			" disk does not match the running cluster name.\n");
>  		goto leave;
>  	}
>  
>

Hi Joseph,

>>> 
> Hi Gang,
> 
> How can we confirm EBADR is only because cluster name mismatch?
> Since the cluster stack may be o2cb(o2dlm) or user(fsdlm).
I looked through all the code of OCFS2 (include o2cb), there is not any place
which returns this error.
In fact, the function calling patch ocfs2_fill_super -> ocfs2_mount_volume
-> ocfs2_dlm_init -> dlm_new_lockspace
is very specific path, we can use this errorno to give the uses a more clear
tip,
since this case looks like a little common during cluster migration, but the
customer can quickly
get the failure cause if there is a error printing.
Also, I think there is not possible to add this errorno in o2cb path during
ocfs2_dlm_init, since o2cb code has been stable for
a long time.   

Thanks
Gang
> 
> Thanks,
> Joseph
> 
> On 17/5/18 14:35, Gang He wrote:
>> This patch is used to add an obvious error message, due to
>> dismatch cluster names between on-disk and in the current cluster.
>> We can meet this case during OCFS2 cluster migration, if we can
>> give the user an obvious tip for why they can not mount the file
>> system after migration, they can quickly fix this dismatch problem.
>> Second, also move printing ocfs2_fill_super() errno to the front
>> of ocfs2_dismount_volume() function, since ocfs2_dismount_volume()
>> will also print it's own message.
>> 
>> Signed-off-by: Gang He <ghe at suse.com>
>> ---
>>  fs/ocfs2/super.c | 8 ++++++--
>>  1 file changed, 6 insertions(+), 2 deletions(-)
>> 
>> diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
>> index ca1646f..5575918 100644
>> --- a/fs/ocfs2/super.c
>> +++ b/fs/ocfs2/super.c
>> @@ -1208,14 +1208,15 @@ static int ocfs2_fill_super(struct super_block
*sb,
> void *data, int silent)
>>  read_super_error:
>>  	brelse(bh);
>>  
>> +	if (status)
>> +		mlog_errno(status);
>> +
>>  	if (osb) {
>>  		atomic_set(&osb->vol_state, VOLUME_DISABLED);
>>  		wake_up(&osb->osb_mount_event);
>>  		ocfs2_dismount_volume(sb, 1);
>>  	}
>>  
>> -	if (status)
>> -		mlog_errno(status);
>>  	return status;
>>  }
>>  
>> @@ -1843,6 +1844,9 @@ static int ocfs2_mount_volume(struct super_block
*sb)
>>  	status = ocfs2_dlm_init(osb);
>>  	if (status < 0) {
>>  		mlog_errno(status);
>> +		if (status == -EBADR)
>> +			mlog(ML_ERROR, "couldn't mount because cluster name
on"
>> +			" disk does not match the running cluster name.\n");
>>  		goto leave;
>>  	}
>>  
>>