From patchwork Fri Jul 24 01:46:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qu Wenruo X-Patchwork-Id: 11681891 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 0D61713A4 for ; Fri, 24 Jul 2020 01:46:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F034122BEA for ; Fri, 24 Jul 2020 01:46:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726692AbgGXBqq (ORCPT ); Thu, 23 Jul 2020 21:46:46 -0400 Received: from mx2.suse.de ([195.135.220.15]:44372 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726430AbgGXBqq (ORCPT ); Thu, 23 Jul 2020 21:46:46 -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 A3D19AE39; Fri, 24 Jul 2020 01:46:52 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Cc: stable@vger.kernel.org, David Sterba Subject: [PATCH] btrfs: reloc: clear DEAD_RELOC_TREE bit for orphan roots to prevent runaway balance Date: Fri, 24 Jul 2020 09:46:40 +0800 Message-Id: <20200724014640.20784-1-wqu@suse.com> X-Mailer: git-send-email 2.27.0 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: # 5.7.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); }