From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:57245 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932387AbdLVIwO (ORCPT ); Fri, 22 Dec 2017 03:52:14 -0500 Subject: Re: [PATCH 08/10] Btrfs: add WARN_ONCE to detect unexpected error from merge_extent_mapping To: Liu Bo , linux-btrfs@vger.kernel.org References: <20171221224256.18196-1-bo.li.liu@oracle.com> <20171221224256.18196-9-bo.li.liu@oracle.com> From: Nikolay Borisov Message-ID: <3fffd583-010a-8b84-3f93-e0a940eeb75e@suse.com> Date: Fri, 22 Dec 2017 10:52:11 +0200 MIME-Version: 1.0 In-Reply-To: <20171221224256.18196-9-bo.li.liu@oracle.com> Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 22.12.2017 00:42, Liu Bo wrote: > This is a subtle case, so in order to understand the problem, it'd be good to > know the content of existing and em when any error occurs. > > Signed-off-by: Liu Bo > --- > fs/btrfs/extent_map.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c > index d386cfb..a8b7e24 100644 > --- a/fs/btrfs/extent_map.c > +++ b/fs/btrfs/extent_map.c > @@ -550,17 +550,23 @@ int btrfs_add_extent_mapping(struct extent_map_tree *em_tree, > *em_in = existing; > ret = 0; > } else { > + u64 orig_start = em->start; > + u64 orig_len = em->len; > + > /* > * The existing extent map is the one nearest to > * the [start, start + len) range which overlaps > */ > ret = merge_extent_mapping(em_tree, existing, > em, start, len); > - free_extent_map(existing); > if (ret) { > free_extent_map(em); > *em_in = NULL; > + WARN_ONCE(ret, KERN_INFO "Unexpected error %d: merge existing(start %llu len %llu) with em(start %llu len %llu)\n", I think this KERN_INFO is spurious and should be removed? > + ret, existing->start, existing->len, > + orig_start, orig_len); > } > + free_extent_map(existing); > } > } > >