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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 949D5C3A5A9 for ; Tue, 5 May 2020 01:52:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6BDBC20705 for ; Tue, 5 May 2020 01:52:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588643574; bh=otlpl9kgwwzoyQGAsBIJNT4k36SElcRlfWNTe5IWlao=; h=Subject:To:References:From:Date:In-Reply-To:List-ID:From; b=vcuLYTPlhpUPs8beEPCVA41656aWiU55Af098mcTf/WOAVDAsXPNr/eQ4PG+Yp9pN Sj19M6iG1XQkXxAySvDazlkZ1F2tdBU3jX8HnUeFK2m+gGU5uX5JWGhLjCy4qSPcgq ugQL5n3qRxQuNrmEcA/xvCACqcujcmG+OvlUuRCQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727991AbgEEBwx (ORCPT ); Mon, 4 May 2020 21:52:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:54322 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726482AbgEEBwx (ORCPT ); Mon, 4 May 2020 21:52:53 -0400 Received: from [192.168.0.107] (unknown [58.213.210.203]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 66A34206C0; Tue, 5 May 2020 01:52:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588643572; bh=otlpl9kgwwzoyQGAsBIJNT4k36SElcRlfWNTe5IWlao=; h=Subject:To:References:From:Date:In-Reply-To:From; b=A40hyaPiyapzdGNG+jUJHa7VQ2T3Wjwrtw1OVfzgaDIfxIXeSTgA43oQ7r2Xbo4Ug SIC9g4ead+0Dv1uTmRsYZSLckqfSOPyHEMdOsg/iV4oMLuWBuxyZXCNw8uE5pl6l6h YsCiuNUTKhUjb0B6zitn1PKycvYpt3DcrwUGbaE0= Subject: Re: [f2fs-dev] [PATCH] f2fs: change maximum zstd compression buffer size To: Jaegeuk Kim , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com References: <20200504143039.155644-1-jaegeuk@kernel.org> From: Chao Yu Message-ID: <7177aab9-630e-e077-7005-0023c93134b3@kernel.org> Date: Tue, 5 May 2020 09:52:47 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20200504143039.155644-1-jaegeuk@kernel.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > 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; >