From nobody Sun May 10 13:21:22 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E5AAC433EF for ; Wed, 4 May 2022 06:09:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344802AbiEDGNN (ORCPT ); Wed, 4 May 2022 02:13:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41924 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232965AbiEDGNL (ORCPT ); Wed, 4 May 2022 02:13:11 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 597D014006; Tue, 3 May 2022 23:09:36 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E1B3D6122E; Wed, 4 May 2022 06:09:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2D33EC385A4; Wed, 4 May 2022 06:09:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1651644575; bh=N6t+QKrUH1bipYHnngO3FWlGNQptDbFS7bpC/zRcyR4=; h=From:To:Cc:Subject:Date:From; b=ocl16qj/RVszFhnHrjRHyWhFSbhZezxnhP2jdAguVrCxdDy/HgrQry5cFItiSyyCr B3/zZ8TjM/zLrt4tNY7l/+MdP/sKDBMzbB7u9d8egBR0xgU63q8cNNYTMfi77fBc8I tuULaFMw0TDqDUF5gFGUMOuHRvXyCX9I01Gjb4UZVqeG2zVR8tBtvUJiG7sq7EzOhI 4j1yfwmUTs0PBvwBPqOHJmcqleJKOQgEw0Dbx2vK71pwadwsPryxaIikVi+RGReFE/ YWtBaaJkoVhOBtw/VVm9USTe69NfxmBMuQD10j0PglSlSfDQtyDF2oeJXviRKBObIp k42XFAY5V+ypw== From: Chao Yu To: jaegeuk@kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Chao Yu , stable@vger.kernel.org, Ming Yan , Chao Yu Subject: [PATCH v3] f2fs: fix deadloop in foreground GC Date: Wed, 4 May 2022 14:09:22 +0800 Message-Id: <20220504060922.3527354-1-chao@kernel.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" As Yanming reported in bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=3D215914 The root cause is: in a very small sized image, it's very easy to exceed threshold of foreground GC, if we calculate free space and dirty data based on section granularity, in corner case, has_not_enough_free_secs() will always return true, result in deadloop in f2fs_gc(). So this patch refactors has_not_enough_free_secs() as below to fix this issue: 1. calculate needed space based on block granularity, and separate all blocks to two parts, section part, and block part, comparing section part to free section, and comparing block part to free space in openned log. 2. account F2FS_DIRTY_NODES, F2FS_DIRTY_IMETA and F2FS_DIRTY_DENTS as node block consumer; 3. account F2FS_DIRTY_DENTS as data block consumer; Cc: stable@vger.kernel.org Reported-by: Ming Yan Signed-off-by: Chao Yu --- v3: - fix incorrect calculation of 'need_upper' variable. fs/f2fs/segment.h | 32 ++++++++++++++++++++------------ 1 file changed, 20 insertions(+), 12 deletions(-) diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h index 8a591455d796..b1951bd30efa 100644 --- a/fs/f2fs/segment.h +++ b/fs/f2fs/segment.h @@ -575,11 +575,10 @@ static inline int reserved_sections(struct f2fs_sb_in= fo *sbi) return GET_SEC_FROM_SEG(sbi, reserved_segments(sbi)); } =20 -static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi) +static inline bool has_curseg_enough_space(struct f2fs_sb_info *sbi, + unsigned int node_blocks, unsigned int dent_blocks) { - unsigned int node_blocks =3D get_pages(sbi, F2FS_DIRTY_NODES) + - get_pages(sbi, F2FS_DIRTY_DENTS); - unsigned int dent_blocks =3D get_pages(sbi, F2FS_DIRTY_DENTS); + unsigned int segno, left_blocks; int i; =20 @@ -605,19 +604,28 @@ static inline bool has_curseg_enough_space(struct f2f= s_sb_info *sbi) static inline bool has_not_enough_free_secs(struct f2fs_sb_info *sbi, int freed, int needed) { - int node_secs =3D get_blocktype_secs(sbi, F2FS_DIRTY_NODES); - int dent_secs =3D get_blocktype_secs(sbi, F2FS_DIRTY_DENTS); - int imeta_secs =3D get_blocktype_secs(sbi, F2FS_DIRTY_IMETA); + unsigned int total_node_blocks =3D get_pages(sbi, F2FS_DIRTY_NODES) + + get_pages(sbi, F2FS_DIRTY_DENTS) + + get_pages(sbi, F2FS_DIRTY_IMETA); + unsigned int total_dent_blocks =3D get_pages(sbi, F2FS_DIRTY_DENTS); + unsigned int node_secs =3D total_node_blocks / BLKS_PER_SEC(sbi); + unsigned int dent_secs =3D total_dent_blocks / BLKS_PER_SEC(sbi); + unsigned int node_blocks =3D total_node_blocks % BLKS_PER_SEC(sbi); + unsigned int dent_blocks =3D total_dent_blocks % BLKS_PER_SEC(sbi); + unsigned int free, need_lower, need_upper; =20 if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING))) return false; =20 - if (free_sections(sbi) + freed =3D=3D reserved_sections(sbi) + needed && - has_curseg_enough_space(sbi)) + free =3D free_sections(sbi) + freed; + need_lower =3D node_secs + dent_secs + reserved_sections(sbi) + needed; + need_upper =3D need_lower + (node_blocks ? 1 : 0) + (dent_blocks ? 1 : 0); + + if (free > need_upper) return false; - return (free_sections(sbi) + freed) <=3D - (node_secs + 2 * dent_secs + imeta_secs + - reserved_sections(sbi) + needed); + else if (free <=3D need_lower) + return true; + return !has_curseg_enough_space(sbi, node_blocks, dent_blocks); } =20 static inline bool f2fs_is_checkpoint_ready(struct f2fs_sb_info *sbi) --=20 2.25.1