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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 EC142C433E0 for ; Mon, 4 Jan 2021 16:19:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B17A820578 for ; Mon, 4 Jan 2021 16:19:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727988AbhADQTZ (ORCPT ); Mon, 4 Jan 2021 11:19:25 -0500 Received: from mx2.suse.de ([195.135.220.15]:44110 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727941AbhADQTZ (ORCPT ); Mon, 4 Jan 2021 11:19:25 -0500 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 C36D8ACAF; Mon, 4 Jan 2021 16:18:43 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 4BBB3DA882; Mon, 4 Jan 2021 17:16:55 +0100 (CET) Date: Mon, 4 Jan 2021 17:16:55 +0100 From: David Sterba To: Qu Wenruo Cc: linux-btrfs@vger.kernel.org, =?iso-8859-1?Q?St=E9phane?= Lesimple Subject: Re: [PATCH] btrfs: relocation: fix wrong file extent type check to avoid false -ENOENT error Message-ID: <20210104161655.GJ6430@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Qu Wenruo , linux-btrfs@vger.kernel.org, =?iso-8859-1?Q?St=E9phane?= Lesimple References: <20201229132934.117325-1-wqu@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20201229132934.117325-1-wqu@suse.com> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Tue, Dec 29, 2020 at 09:29:34PM +0800, Qu Wenruo wrote: > [BUG] > There are several bug reports about recent kernel unable to relocate > certain data block groups. > > Sometimes the error just go away, but there is one reporter who can > reproduce it reliably. > > The dmesg would look like: > [ 438.260483] BTRFS info (device dm-10): balance: start -dvrange=34625344765952..34625344765953 > [ 438.269018] BTRFS info (device dm-10): relocating block group 34625344765952 flags data|raid1 > [ 450.439609] BTRFS info (device dm-10): found 167 extents, stage: move data extents > [ 463.501781] BTRFS info (device dm-10): balance: ended with status: -2 > > [CAUSE] > The -ENOENT error is returned from the following chall chain: > > add_data_references() > |- delete_v1_space_cache(); > |- if (!found) > return -ENOENT; > > The variable @found is set to true if we find a data extent whose > disk bytenr matches parameter @data_bytes. > > With extra debug, the offending tree block looks like this: > leaf bytenr = 42676709441536, data_bytenr = 34626327621632 > > ctime 1567904822.739884119 (2019-09-08 03:07:02) > mtime 0.0 (1970-01-01 01:00:00) > otime 0.0 (1970-01-01 01:00:00) > item 27 key (51933 EXTENT_DATA 0) itemoff 9854 itemsize 53 > generation 1517381 type 2 (prealloc) > prealloc data disk byte 34626327621632 nr 262144 <<< > prealloc data offset 0 nr 262144 > item 28 key (52262 ROOT_ITEM 0) itemoff 9415 itemsize 439 > generation 2618893 root_dirid 256 bytenr 42677048360960 level 3 refs 1 > lastsnap 2618893 byte_limit 0 bytes_used 5557338112 flags 0x0(none) > uuid d0d4361f-d231-6d40-8901-fe506e4b2b53 > > Although item 27 has disk bytenr 34626327621632, which matches the > data_bytenr, its type is prealloc, not reg. > This makes the existing code skip that item, and return -ENOENT. > > [FIX] > The code is modified in commit 19b546d7a1b2 ("btrfs: relocation: Use > btrfs_find_all_leafs to locate data extent parent tree leaves"), before > that commit, we use something like > "if (type == BTRFS_FILE_EXTENT_INLINE) continue;". > > But in that offending commit, we use (type == BTRFS_FILE_EXTENT_REG), > ignoring BTRFS_FILE_EXTENT_PREALLOC. > > Fix it by also checking BTRFS_FILE_EXTENT_PREALLOC. > > Reported-by: Stéphane Lesimple > Fixes: 19b546d7a1b2 ("btrfs: relocation: Use btrfs_find_all_leafs to locate data extent parent tree leaves") > Signed-off-by: Qu Wenruo Thank you all for tracking down the bug, added to misc-next.