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=-7.1 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 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 2366EC28CBC for ; Wed, 6 May 2020 14:56:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9DFF208DB for ; Wed, 6 May 2020 14:56:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588776971; bh=LEE9kaUuq3swcyipv2Z5cVdwEM6Qz9YdRajLpVMAeUs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=xaUjLLBeALmpRXcWWE4A4dBHTu9f/y5R0nOR4f94+H0fjoDPjoVHGIlFvDT52DtQD 7dDJxdLHkDB5Zu+OLdKn6barH/H1odjuyR1NQfJ6JsHH9N0xP9xMpT0mnq0l5G8ODf E7xZynqTOFSbD+BFNdYYIOxo6Xxxd79JO5PtSjtU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729367AbgEFO4K (ORCPT ); Wed, 6 May 2020 10:56:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:45746 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729078AbgEFO4J (ORCPT ); Wed, 6 May 2020 10:56:09 -0400 Received: from localhost (unknown [104.132.1.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2B32C208D5; Wed, 6 May 2020 14:56:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588776969; bh=LEE9kaUuq3swcyipv2Z5cVdwEM6Qz9YdRajLpVMAeUs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Xx0fK9FbNR3TwpC9RsM9U17z+Mt/rhgEorkbaAzNLrrJ5WXebxTK6DxpMb2Sts2Kt 2WZlLZ3Z4qZT1yyx73AZOjHrvnd1l+JnjbHu8P9OJ7Gz9mYE7Cx8da7oJKDsWObkY/ Ym2zOZ0YfaUYi7Ja/4gf4WIJLkZzi6HrVMsxYrx0= Date: Wed, 6 May 2020 07:56:08 -0700 From: Jaegeuk Kim To: Chao Yu Cc: Chao Yu , kernel-team@android.com, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [f2fs-dev] [PATCH] f2fs: change maximum zstd compression buffer size Message-ID: <20200506145608.GD107238@google.com> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9aaeac5e-4511-5c81-653c-23a85b3c335a@huawei.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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). > > 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 > > . > >