Re: [PATCH] ocfs2: update seq_file index in ocfs2_dlm_seq_next

[Wengang Wang]

> On Nov 10, 2024, at 5:38 PM, Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx> wrote:
> 
> 
> 
> On 11/9/24 3:28 AM, Wengang Wang wrote:
>> The following INFO level message was seen:
>> 
>> seq_file: buggy .next function ocfs2_dlm_seq_next [ocfs2] did not
>> update position index
>> 
>> Fix:
>> Updata m->index to make seq_read_iter happy though the index its self makes
>> no sense to ocfs2_dlm_seq_next.
>> 
>> Signed-off-by: Wengang Wang <wen.gang.wang@xxxxxxxxxx>
>> ---
>> fs/ocfs2/dlmglue.c | 1 +
>> 1 file changed, 1 insertion(+)
>> 
>> diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
>> index 60df52e4c1f8..349d131369cf 100644
>> --- a/fs/ocfs2/dlmglue.c
>> +++ b/fs/ocfs2/dlmglue.c
>> @@ -3120,6 +3120,7 @@ static void *ocfs2_dlm_seq_next(struct seq_file *m, void *v, loff_t *pos)
>> }
>> spin_unlock(&ocfs2_dlm_tracking_lock);
>> 
>> + m->index++;
> 
> We can directly use '(*pos)++' instead.
> 

The input/output "pos” indicates more an offset into the file. Actually the output for an item is not really 1 byte in length, so incrementing the offset by 1 sounds a bit strange to me. Instead If we increment the “index”, It would be easier to understand it as  for next item. Though updating “index” or updating “*pos” instead makes no difference to binary running, the code understanding is different.  I know other seq_operations.next functions are directly incrementing the “*pos”, I think updating “index” is better. Well, if you persist (*pos)++, I will also let it go.

Thanks,
Wengang