Re: [PATCH v2 2/3] Btrfs: rescan for qgroups

[Jan Schmidt <mail@jan-o-sch.net>]

On Tue, April 16, 2013 at 12:08 (+0200), Wang Shilong wrote:
> Hello Jan,
>  
> 
>>  	slot = path->slots[0];
>>  	ptr = btrfs_item_ptr(l, slot, struct btrfs_qgroup_status_item);
>> +	spin_lock(&fs_info->qgroup_lock);
> 
> 
> Why we need hold qgroup_lock here? would you please explain...

It would have been easier for me if you had left the relevant context in there,
but I finally found it.

Thinking again about it, as update_qgroup_status_item is only called from
transaction commit context, we can do without a spinlock here. I meant to
protect fs_info->qgroup_flags and fs_info->qgroup_rescan_progress, but it seems
not required.

Thanks,
-Jan