On Tue, Sep 11, 2018 at 01:38:16PM +0800, Qu Wenruo wrote:
> Reloc tree doesn't contribute to qgroup numbers, as we have
> accounted them at balance time (check replace_path()).
>
> Skip such unneeded subtree trace should reduce some performance
> overhead.
>
> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
> ---
> fs/btrfs/extent-tree.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index de6f75f5547b..4588153f414c 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -8643,7 +8643,13 @@ static noinline int do_walk_down(struct btrfs_trans_handle *trans,
> parent = 0;
> }
>
> - if (need_account) {
> + /*
> + * Tree reloc tree doesn't contribute to qgroup numbers, and
As you're going to send another iteration, please update the 'tree reloc
tree' references here and in other patches too.
> + * we have already accounted them at merge time (replace_path),
> + * thus we could skip expensive subtree trace here.
> + */
> + if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
> + need_account) {
> ret = btrfs_qgroup_trace_subtree(trans, next,
> generation, level - 1);
> if (ret) {
> --
> 2.18.0
