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.
-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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