From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0ED03C4363D for ; Tue, 22 Sep 2020 15:28:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BA16C214F1 for ; Tue, 22 Sep 2020 15:28:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726662AbgIVP2t (ORCPT ); Tue, 22 Sep 2020 11:28:49 -0400 Received: from mx2.suse.de ([195.135.220.15]:59960 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726566AbgIVP2s (ORCPT ); Tue, 22 Sep 2020 11:28:48 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 9D541ABC4; Tue, 22 Sep 2020 15:29:24 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 84E05DA6E9; Tue, 22 Sep 2020 17:27:32 +0200 (CEST) Date: Tue, 22 Sep 2020 17:27:32 +0200 From: David Sterba To: Josef Bacik Cc: linux-btrfs@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH 1/2] btrfs: init device stats for seed devices Message-ID: <20200922152732.GF6756@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Josef Bacik , linux-btrfs@vger.kernel.org, kernel-team@fb.com References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Fri, Sep 18, 2020 at 04:44:32PM -0400, Josef Bacik wrote: > We recently started recording device stats across the fleet, and noticed > a large increase in messages such as this > > BTRFS warning (device dm-0): get dev_stats failed, not yet valid > > on our tiers that use seed devices for their root devices. This is > because we do not initialize the device stats for any seed devices if we > have a sprout device and mount using that sprout device. The basic > steps for reproducing are > > mkfs seed device > mount seed device > fill seed device > umount seed device > btrfstune -S 1 seed device > mount seed device > btrfs device add -f sprout device /mnt/wherever > umount /mnt/wherever > mount sprout device /mnt/wherever > btrfs device stats /mnt/wherever Please turn that into a fstest.