From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.cn.fujitsu.com ([183.91.158.132]:58208 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756138AbeDXFq4 (ORCPT ); Tue, 24 Apr 2018 01:46:56 -0400 Received: from G08CNEXCHPEKD03.g08.fujitsu.local (unknown [10.167.33.85]) by cn.fujitsu.com (Postfix) with ESMTP id 938B349F19D1 for ; Tue, 24 Apr 2018 13:46:50 +0800 (CST) From: Su Yue To: CC: Subject: [PATCH 3/3] btrfs-progs: do not merge tree block refs have different root_id Date: Tue, 24 Apr 2018 13:52:33 +0800 Message-ID: <20180424055233.6420-3-suy.fnst@cn.fujitsu.com> In-Reply-To: <20180424055233.6420-1-suy.fnst@cn.fujitsu.com> References: <20180424055233.6420-1-suy.fnst@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-btrfs-owner@vger.kernel.org List-ID: For an extent item which contains many tree block backrefs, like ================================================================= In 020-extent-ref-cases/keyed_block_ref.img item 10 key (29470720 METADATA_ITEM 0) itemoff 3450 itemsize 222 refs 23 gen 10 flags TREE_BLOCK tree block skinny level 0 tree block backref root 278 tree block backref root 277 tree block backref root 276 tree block backref root 275 tree block backref root 274 tree block backref root 273 tree block backref root 272 tree block backref root 271 tree block backref root 270 tree block backref root 269 tree block backref root 268 tree block backref root 267 tree block backref root 266 tree block backref root 265 tree block backref root 264 tree block backref root 263 tree block backref root 262 tree block backref root 261 tree block backref root 260 tree block backref root 259 tree block backref root 258 tree block backref root 257 ================================================================= In find_parent_nodes(), these refs's parents are 0, then __merge_refs will merge refs to one ref. It causes only one root to be returned. So, if both parents are 0, do not merge refs. Lowmem check calls find_parent_nodes frequently to decide whether. check an extent buffer or not. These bug influences bytes accounting. Signed-off-by: Su Yue --- backref.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/backref.c b/backref.c index 51553c702187..daadb6299c79 100644 --- a/backref.c +++ b/backref.c @@ -507,6 +507,8 @@ static void __merge_refs(struct pref_state *prefstate, int mode) } else { if (ref1->parent != ref2->parent) continue; + if (ref1->parent == 0) + continue; } eie = ref1->inode_list; -- 2.17.0