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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 13B7EC28CBC for ; Thu, 7 May 2020 02:48:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D480021835 for ; Thu, 7 May 2020 02:48:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728066AbgEGCsv (ORCPT ); Wed, 6 May 2020 22:48:51 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:3829 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726529AbgEGCsv (ORCPT ); Wed, 6 May 2020 22:48:51 -0400 Received: from DGGEMS407-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 1DE0E82E181631CA2E78; Thu, 7 May 2020 10:48:50 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.207) with Microsoft SMTP Server (TLS) id 14.3.487.0; Thu, 7 May 2020 10:48:48 +0800 Subject: Re: [f2fs-dev] [PATCH] f2fs: change maximum zstd compression buffer size To: Jaegeuk Kim CC: Chao Yu , , , References: <20200504143039.155644-1-jaegeuk@kernel.org> <7177aab9-630e-e077-7005-0023c93134b3@kernel.org> <20200505230559.GA203407@google.com> <9aaeac5e-4511-5c81-653c-23a85b3c335a@huawei.com> <20200506145608.GD107238@google.com> From: Chao Yu Message-ID: <96140ec8-0fa9-9e4d-4459-1f26737865bf@huawei.com> Date: Thu, 7 May 2020 10:48:48 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20200506145608.GD107238@google.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/5/6 22:56, Jaegeuk Kim wrote: > On 05/06, Chao Yu wrote: >> On 2020/5/6 7:05, Jaegeuk Kim wrote: >>> On 05/05, Chao Yu wrote: >>>> On 2020-5-4 22:30, Jaegeuk Kim wrote: >>>>> From: Daeho Jeong >>>>> >>>>> Current zstd compression buffer size is one page and header size less >>>>> than cluster size. By this, zstd compression always succeeds even if >>>>> the real compression data is failed to fit into the buffer size, and >>>>> eventually reading the cluster returns I/O error with the corrupted >>>>> compression data. >>>> >>>> What's the root cause of this issue? I didn't get it. >>>> >>>>> >>>>> Signed-off-by: Daeho Jeong >>>>> --- >>>>> fs/f2fs/compress.c | 4 ++-- >>>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>>> >>>>> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c >>>>> index 4c7eaeee52336..a9fa8049b295f 100644 >>>>> --- a/fs/f2fs/compress.c >>>>> +++ b/fs/f2fs/compress.c >>>>> @@ -313,7 +313,7 @@ static int zstd_init_compress_ctx(struct compress_ctx *cc) >>>>> cc->private = workspace; >>>>> cc->private2 = stream; >>>>> >>>>> - cc->clen = cc->rlen - PAGE_SIZE - COMPRESS_HEADER_SIZE; >>>>> + cc->clen = ZSTD_compressBound(PAGE_SIZE << cc->log_cluster_size); >>>> >>>> In my machine, the value is 66572 which is much larger than size of dst >>>> buffer, so, in where we can tell the real size of dst buffer to zstd >>>> compressor? Otherwise, if compressed data size is larger than dst buffer >>>> size, when we flush compressed data into dst buffer, we may suffer overflow. >>> >>> Could you give it a try compress_log_size=2 and check decompression works? >> >> I tried some samples before submitting the patch, did you encounter app's data >> corruption when using zstd algorithm? If so, let me check this issue. > > Daeho reported: > 1. cp -a src_file comp_dir/dst_file (comp_dir is a directory for compression) > 2. sync comp_dir/dst_file > 3. echo 3 > /proc/sys/vm/drop_caches > 4. cat comp_dir/dst_file > dump (it returns I/O error depending on the file). Let me check this issue. Thanks, > >> >> Thanks, >> >>> >>>> >>>>> return 0; >>>>> } >>>>> >>>>> @@ -330,7 +330,7 @@ static int zstd_compress_pages(struct compress_ctx *cc) >>>>> ZSTD_inBuffer inbuf; >>>>> ZSTD_outBuffer outbuf; >>>>> int src_size = cc->rlen; >>>>> - int dst_size = src_size - PAGE_SIZE - COMPRESS_HEADER_SIZE; >>>>> + int dst_size = cc->clen; >>>>> int ret; >>>>> >>>>> inbuf.pos = 0; >>>>> >>> >>> >>> _______________________________________________ >>> Linux-f2fs-devel mailing list >>> Linux-f2fs-devel@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel >>> . >>> > . >