From patchwork Fri Jul 24 02:00:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qu Wenruo X-Patchwork-Id: 11681895 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 0911513B4 for ; Fri, 24 Jul 2020 02:00:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E582D20792 for ; Fri, 24 Jul 2020 02:00:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726737AbgGXCAh (ORCPT ); Thu, 23 Jul 2020 22:00:37 -0400 Received: from mx2.suse.de ([195.135.220.15]:46896 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726381AbgGXCAh (ORCPT ); Thu, 23 Jul 2020 22:00:37 -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 CB33BB130; Fri, 24 Jul 2020 02:00:43 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Cc: stable@vger.kernel.org, David Sterba Subject: [PATCH 2/2] btrfs: reloc: clear DEAD_RELOC_TREE bit for orphan roots to prevent runaway balance Date: Fri, 24 Jul 2020 10:00:26 +0800 Message-Id: <20200724020027.31751-2-wqu@suse.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200724020027.31751-1-wqu@suse.com> References: <20200724020027.31751-1-wqu@suse.com> MIME-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org 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: # 5.4.x Signed-off-by: Qu Wenruo [Manually solve the conflicts due to no btrfs root refs rework] Signed-off-by: David Sterba --- fs/btrfs/relocation.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 3f8c706d75ee..1b087ee338cc 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -2540,6 +2540,8 @@ void merge_reloc_roots(struct reloc_control *rc) if (!IS_ERR(root)) { if (root->reloc_root == reloc_root) root->reloc_root = NULL; + clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE, + &root->state); } list_del_init(&reloc_root->root_list);