From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:47298 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755155AbeEAO6k (ORCPT ); Tue, 1 May 2018 10:58:40 -0400 Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id A6EEAAF0B for ; Tue, 1 May 2018 14:58:39 +0000 (UTC) Date: Tue, 1 May 2018 16:56:04 +0200 From: David Sterba To: Qu Wenruo Cc: linux-btrfs@vger.kernel.org Subject: Re: [PATCH] btrfs: trace: Allow trace_qgroup_update_counters() to record old rfer/excl value Message-ID: <20180501145604.GV21272@twin.jikos.cz> Reply-To: dsterba@suse.cz References: <20180430070444.23837-1-wqu@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20180430070444.23837-1-wqu@suse.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Mon, Apr 30, 2018 at 03:04:44PM +0800, Qu Wenruo wrote: > Origin trace_qgroup_update_counters() only records qgroup id and its > reference count change. > > It's good enough to debug qgroup accounting change, but when rescan race > is involved, it's pretty hard to distinguish which modification belongs > to which rescan. > > So add old_rfer and old_excl trace output to help distinguishing > different rescan instance. > (Different rescan instance should reset its qgroup->rfer to 0) > > For trace event parameter, it just changes from u64 qgroup_id to struct > btrfs_qgroup *qgroup, so number of parameters is not changed at all. > > Signed-off-by: Qu Wenruo Reviewed-by: David Sterba