Hello Jan,
> On Tue, May 07, 2013 at 08:15 (+0200), Wang Shilong wrote:
>> If qgroup_rescan worker is in progress, we should ignore
>> the extent that has not been dealt with qgroup_rescan worker,just
>> let them dealt later otherwise we may get wrong qgroup accounting.
>>
>> However, we have checked this before find_all_roots() without spin_lock.
>> When doing qgroup accounting, we don't have to check it again, because
>> during this period,qgroup_rescan worker can deal with more extents and
>> qgroup_rescan_extent->objectid can only go larger, so here the check
>> is unnecessary.
>>
>> Just remove this check, so that we don't need hold qgroup_rescan_lock
>> when doing qgroup accounting.
>
> NAK.
>
> After a discussion on that lock the last thing in this thread I see is ...
>
> On Wed, May 01, 2013 at 13:57 (+0200), Jan Schmidt wrote:
>> Now I see what you mean. The second check is only required when we start
>> a rescan operation after the initial check in btrfs_qgroup_account_ref.
>
> Please continue on that argument, your commit message doesn't explain at all why
> we should be safe to remove this check.
You are right!
Thanks,
Wang
>
> -Jan
>
>> Signed-off-by: Wang Shilong <wangsl-fnst@xxxxxxxxxxxxxx>
>> ---
>> fs/btrfs/qgroup.c | 9 ---------
>> 1 files changed, 0 insertions(+), 9 deletions(-)
>>
>> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
>> index d059d86..2710784 100644
>> --- a/fs/btrfs/qgroup.c
>> +++ b/fs/btrfs/qgroup.c
>> @@ -1445,15 +1445,7 @@ int btrfs_qgroup_account_ref(struct btrfs_trans_handle *trans,
>> if (ret < 0)
>> return ret;
>>
>> - mutex_lock(&fs_info->qgroup_rescan_lock);
>> spin_lock(&fs_info->qgroup_lock);
>> - if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
>> - if (fs_info->qgroup_rescan_progress.objectid <= node->bytenr) {
>> - ret = 0;
>> - goto unlock;
>> - }
>> - }
>> -
>> quota_root = fs_info->quota_root;
>> if (!quota_root)
>> goto unlock;
>> @@ -1492,7 +1484,6 @@ int btrfs_qgroup_account_ref(struct btrfs_trans_handle *trans,
>>
>> unlock:
>> spin_unlock(&fs_info->qgroup_lock);
>> - mutex_unlock(&fs_info->qgroup_rescan_lock);
>> ulist_free(roots);
>>
>> return ret;
>>
>
>
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