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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 1D132C433DF for ; Fri, 24 Jul 2020 09:42:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 00DEC206EB for ; Fri, 24 Jul 2020 09:42:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727058AbgGXJmO (ORCPT ); Fri, 24 Jul 2020 05:42:14 -0400 Received: from mx2.suse.de ([195.135.220.15]:54798 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726114AbgGXJmO (ORCPT ); Fri, 24 Jul 2020 05:42:14 -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 DDF4FAD46; Fri, 24 Jul 2020 09:42:20 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 9D4FADA791; Fri, 24 Jul 2020 11:41:45 +0200 (CEST) Date: Fri, 24 Jul 2020 11:41:45 +0200 From: David Sterba To: Qu Wenruo Cc: linux-btrfs@vger.kernel.org, stable@vger.kernel.org, David Sterba Subject: Re: [PATCH] btrfs: reloc: clear DEAD_RELOC_TREE bit for orphan roots -- for 5.7 to prevent runaway balance Message-ID: <20200724094145.GG3703@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Qu Wenruo , linux-btrfs@vger.kernel.org, stable@vger.kernel.org, David Sterba References: <20200724014640.20784-1-wqu@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200724014640.20784-1-wqu@suse.com> 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 Qu, you need to make the target version visible in the subject. The manual submissions to stable are processed by humans, while the CC: tag is for semi-automatic collection of patches that get merged to master. If you send 3 patches with same subjects it could be ignored as resends or it's required to read all the changelogs. On Fri, Jul 24, 2020 at 09:46:40AM +0800, Qu Wenruo wrote: > commit 1dae7e0e58b484eaa43d530f211098fdeeb0f404 upstream. > > [BUG] > There are several reported runaway balance, that balance is flooding the > log with "found X extents" where the X never changes. > > [CAUSE] > Commit d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after > merge_reloc_roots") introduced BTRFS_ROOT_DEAD_RELOC_TREE bit to > indicate that one subvolume has finished its tree blocks swap with its > reloc tree. > > However if balance is canceled or hits ENOSPC halfway, we didn't clear > the BTRFS_ROOT_DEAD_RELOC_TREE bit, leaving that bit hanging forever > until unmount. > > Any subvolume root with that bit, would cause backref cache to skip this > tree block, as it has finished its tree block swap. This would cause > all tree blocks of that root be ignored by balance, leading to runaway > balance. > > [FIX] > Fix the problem by also clearing the BTRFS_ROOT_DEAD_RELOC_TREE bit for > the original subvolume of orphan reloc root. > > Add an umount check for the stale bit still set. > > Fixes: d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots") > Cc: # 5.7.x > Signed-off-by: Qu Wenruo > Signed-off-by: David Sterba > --- > fs/btrfs/disk-io.c | 1 + > fs/btrfs/relocation.c | 2 ++ > 2 files changed, 3 insertions(+) > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index f71e4dbe1d8a..f00e64fee5dd 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -1998,6 +1998,7 @@ void btrfs_put_root(struct btrfs_root *root) > > if (refcount_dec_and_test(&root->refs)) { > WARN_ON(!RB_EMPTY_ROOT(&root->inode_tree)); > + WARN_ON(test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state)); > if (root->anon_dev) > free_anon_bdev(root->anon_dev); > btrfs_drew_lock_destroy(&root->snapshot_lock); > diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c > index 157452a5e110..f67d736c27a1 100644 > --- a/fs/btrfs/relocation.c > +++ b/fs/btrfs/relocation.c > @@ -2642,6 +2642,8 @@ void merge_reloc_roots(struct reloc_control *rc) > root->reloc_root = NULL; > btrfs_put_root(reloc_root); > } > + clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE, > + &root->state); > btrfs_put_root(root); > } > > -- > 2.27.0