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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 A2AC0C3F2C6 for ; Tue, 3 Mar 2020 15:34:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7DC892083E for ; Tue, 3 Mar 2020 15:34:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729581AbgCCPez (ORCPT ); Tue, 3 Mar 2020 10:34:55 -0500 Received: from mx2.suse.de ([195.135.220.15]:35456 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727972AbgCCPez (ORCPT ); Tue, 3 Mar 2020 10:34:55 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id DC01FB138; Tue, 3 Mar 2020 15:34:53 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id F31C4DA7AE; Tue, 3 Mar 2020 16:34:31 +0100 (CET) Date: Tue, 3 Mar 2020 16:34:31 +0100 From: David Sterba To: Josef Bacik Cc: dsterba@suse.cz, kernel-team@fb.com, linux-btrfs@vger.kernel.org Subject: Re: [PATCH 5/7] btrfs: clear BTRFS_ROOT_DEAD_RELOC_TREE before dropping the reloc root Message-ID: <20200303153431.GF2902@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Josef Bacik , kernel-team@fb.com, linux-btrfs@vger.kernel.org References: <20200302184757.44176-1-josef@toxicpanda.com> <20200302184757.44176-6-josef@toxicpanda.com> <20200302193120.GS2902@twin.jikos.cz> 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) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Mon, Mar 02, 2020 at 02:51:11PM -0500, Josef Bacik wrote: > On 3/2/20 2:31 PM, David Sterba wrote: > > On Mon, Mar 02, 2020 at 01:47:55PM -0500, Josef Bacik wrote: > >> We were doing the clear dance for the reloc root after doing the drop of > >> the reloc root, which means we have a giant window where we could miss > >> having BTRFS_ROOT_DEAD_RELOC_TREE unset and the reloc_root == NULL. > >> > >> Signed-off-by: Josef Bacik > >> --- > >> fs/btrfs/relocation.c | 13 +++++++------ > >> 1 file changed, 7 insertions(+), 6 deletions(-) > >> > >> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c > >> index e60450c44406..acd21c156378 100644 > >> --- a/fs/btrfs/relocation.c > >> +++ b/fs/btrfs/relocation.c > >> @@ -2291,18 +2291,19 @@ static int clean_dirty_subvols(struct reloc_control *rc) > >> > >> list_del_init(&root->reloc_dirty_list); > >> root->reloc_root = NULL; > >> - if (reloc_root) { > >> - > >> - ret2 = btrfs_drop_snapshot(reloc_root, NULL, 0, 1); > >> - if (ret2 < 0 && !ret) > >> - ret = ret2; > >> - } > >> /* > >> * Need barrier to ensure clear_bit() only happens after > >> * root->reloc_root = NULL. Pairs with have_reloc_root. > >> */ > >> smp_wmb(); > >> clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state); > >> + > >> + if (reloc_root) { > >> + > >> + ret2 = btrfs_drop_snapshot(reloc_root, NULL, 0, 1); > >> + if (ret2 < 0 && !ret) > >> + ret = ret2; > >> + } > > > > This reverts fix 1fac4a54374f7ef385938f3c6cf7649c0fe4f6cd that moved if > > (reloc_root) before the clear_bit. > > > > Hmm we should probably keep this and move the > > if (root->reloc_root) > > thing after the > > if (!rc || !rc->create_reloc_tree || > root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) > return 0; > > to properly fix this. I'll add this and send an updated series. Thanks, Also please update the changelog, it's too vague for a code that had several bugs regarding the reloc_root lifetime.