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=-6.5 required=3.0 tests=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 4D1CCC46475 for ; Wed, 24 Oct 2018 02:55:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 096B52082F for ; Wed, 24 Oct 2018 02:55:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 096B52082F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gmx.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-btrfs-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726409AbeJXLVh (ORCPT ); Wed, 24 Oct 2018 07:21:37 -0400 Received: from mout.gmx.net ([212.227.17.22]:37883 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726073AbeJXLVh (ORCPT ); Wed, 24 Oct 2018 07:21:37 -0400 Received: from [0.0.0.0] ([149.28.201.231]) by mail.gmx.com (mrgmx101 [212.227.17.174]) with ESMTPSA (Nemesis) id 0M0cs6-1fKONc0yvG-00uq3v; Wed, 24 Oct 2018 02:13:27 +0200 Received: from [0.0.0.0] ([149.28.201.231]) by mail.gmx.com (mrgmx101 [212.227.17.174]) with ESMTPSA (Nemesis) id 0M0cs6-1fKONc0yvG-00uq3v; Wed, 24 Oct 2018 02:13:27 +0200 Subject: Re: [PATCH 04/13] btrfs-progs: lowmem: fix false alert about the existence of gaps in the check_file_extent To: Su Yue , linux-btrfs@vger.kernel.org Cc: Lu Fengqi References: <20181023094147.7906-1-suy.fnst@cn.fujitsu.com> <20181023094147.7906-5-suy.fnst@cn.fujitsu.com> From: Qu Wenruo Openpgp: preference=signencrypt Autocrypt: addr=quwenruo.btrfs@gmx.com; prefer-encrypt=mutual; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNIlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT7CwJQEEwEIAD4CGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCWdWCnQUJCWYC bgAKCRDCPZHzoSX+qAR8B/94VAsSNygx1C6dhb1u1Wp1Jr/lfO7QIOK/nf1PF0VpYjTQ2au8 ihf/RApTna31sVjBx3jzlmpy+lDoPdXwbI3Czx1PwDbdhAAjdRbvBmwM6cUWyqD+zjVm4RTG rFTPi3E7828YJ71Vpda2qghOYdnC45xCcjmHh8FwReLzsV2A6FtXsvd87bq6Iw2axOHVUax2 FGSbardMsHrya1dC2jF2R6n0uxaIc1bWGweYsq0LXvLcvjWH+zDgzYCUB0cfb+6Ib/ipSCYp 3i8BevMsTs62MOBmKz7til6Zdz0kkqDdSNOq8LgWGLOwUTqBh71+lqN2XBpTDu1eLZaNbxSI ilaVzsBNBFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcga CbPEwhLj1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj /IrRUUka68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fN GSsRb+pKEKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0 q1eW4Jrv0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEv ABEBAAHCwHwEGAEIACYWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCWdWBrwIbDAUJA8JnAAAK CRDCPZHzoSX+qA3xB/4zS8zYh3Cbm3FllKz7+RKBw/ETBibFSKedQkbJzRlZhBc+XRwF61mi f0SXSdqKMbM1a98fEg8H5kV6GTo62BzvynVrf/FyT+zWbIVEuuZttMk2gWLIvbmWNyrQnzPl mnjK4AEvZGIt1pk+3+N/CMEfAZH5Aqnp0PaoytRZ/1vtMXNgMxlfNnb96giC3KMR6U0E+siA 4V7biIoyNoaN33t8m5FwEwd2FQDG9dAXWhG13zcm9gnk63BN3wyCQR+X5+jsfBaS4dvNzvQv h8Uq/YGjCoV1ofKYh3WKMY8avjq25nlrhzD/Nto9jHp8niwr21K//pXVA81R2qaXqGbql+zo Message-ID: <665a8b5f-c463-6dde-a5cc-959d84c44378@gmx.com> Date: Wed, 24 Oct 2018 08:13:21 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20181023094147.7906-5-suy.fnst@cn.fujitsu.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Provags-ID: V03:K1:klQyPemhNw6OSMP/o7PjWp3Lwo+HxhHO9A2RVeWFe6h86xpgy60 WovlMvFHlLFsG4mr9bfFNPajro6naR05HKzsMJoDxSTRXJ46XCggnP9NvoBbDXuo1DcQFOx uBD/a1eXLIDOuBRFLmK0EB05e7MRCGJgurUR/TRTC4kwnFPl/cixJ2U6B8yI9yozF9tzoYU 6F3DeiwlAm037HF8oGwJg== X-UI-Out-Filterresults: notjunk:1;V01:K0:11r/BBj5lZ8=:yGzc3t2Pth8SGbI/3KUpPT 3d8tQjr2Fw7U66RxlO5eh145FpHpv7JGoctjMn9PryNTA6CN0oGVnYbJdjUbAQgvKoFjqgr24 hLqVQoMHKhac6qFxarBGT+IAhgEi7VLL3cwKMWA/+1h5ppe0V5Z/bnM7dobIwodxSOovTmIMG SE8op2sBEDKrC60yQKPADz0FA/kf7OqBZewyJjgmfJxnvalwMbrNEgx8qPjpynaO8JKCqU8H4 06KJknBuSYX2YC6VaG5P0ZKT1azWXlS7ygewPVfyUSEvb6/34El5lJgsurzsVkW6KMiJzVjlz /6iYJz/wEvX57AkD3WzCXRadbclBRo3H73lmCKM/AySu5azNLioyAEEHhkZL9Fos4g0pebSDP moqHh1RTQ0nCF/L0o7M/K2x5B9ea7wVRQqbiS3HdHsOoeMus3Yx8GhJP+xU7aBwK2lbDr3Cz+ R3FRY2iIJz7e3/q3ytxi9U27VKCaEOhL/Q+LJYekSLAzZ+AZXuy++8FmqZNIk698W7Zd7o0rj 6UeP2q3GMsnFk2yiWqXAFURkqy+83Tt0ZGtI6wiacCDyxNIqkNgpW7EcHNsZy8GYjXeIBiouP 9Xrs0KUDtAwmxVPRaVDdeaU/QlgWK0PeYFgpLHxGTt9sq8wtEyl+eCeEypzXMOqqEb+fmGe92 ft9Ia/l3XDyt/KGu24jcd74k+hrfcakA3bFwg6rLC5mHofNuRFxQYXtGZQtX0snbmYDRdOK8i voO9CvPq9x/8VUwAuT29crUIpkOWc/jP0i8NGLad+dA284TwoOojvV8HRMW93A5twwWKktLMU VAZBHmZbQycm7aBIsxi+s31iroOPRwTAwRw6MPTZahjRjT+YOk= Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 2018/10/23 下午5:41, Su Yue wrote: > From: Lu Fengqi > > The 'end' parameter of check_file_extent tracks the ending offset of the > last checked extent. This is used to detect gaps between adjacent extents. > > Currently such gaps are wrongly detected since for regular extents only > the size of the extent is added to the 'end' parameter. This results in > wrongly considering all extents of a file as having gaps between them > when only 2 of them really have a gap as seen in the example below. > > Solution: > The extent_end variable should set to the sum of the offset and the > extent_num_bytes of the file extent. > > Example: > Suppose that lowmem check the following file extent of inode 257. > > item 6 key (257 EXTENT_DATA 0) itemoff 15813 itemsize 53 > generation 6 type 1 (regular) > extent data disk byte 13631488 nr 4096 > extent data offset 0 nr 4096 ram 4096 > extent compression 0 (none) > item 7 key (257 EXTENT_DATA 8192) itemoff 15760 itemsize 53 > generation 6 type 1 (regular) > extent data disk byte 13631488 nr 4096 > extent data offset 0 nr 4096 ram 4096 > extent compression 0 (none) > item 8 key (257 EXTENT_DATA 12288) itemoff 15707 itemsize 53 > generation 6 type 1 (regular) > extent data disk byte 13631488 nr 4096 > extent data offset 0 nr 4096 ram 4096 > extent compression 0 (none) > > For inode 257, check_inode_item set extent_end to 0, then call > check_file_extent to check item {6,7,8}. > item 6) > offset(0) == extent_end(0) > extent_end = extent_end(0) + extent_num_bytes(4096) > item 7) > offset(8192) != extent_end(4096) > extent_end = extent_end(4096) + extent_num_bytes(4096) > ^^^ The problem is all about a gap screwing up all later accounting. So it's indeed a problem. > The old extent_end should replace by offset(8192). > item 8) > offset(12288) != extent_end(8192) > ^^^ > But there is no gap between item {7,8}. > > Fixes: d88da10ddd42 ("btrfs-progs: check: introduce function to check file extent") > Signed-off-by: Lu Fengqi Reviewed-by: Qu Wenruo Thanks, Qu > --- > check/mode-lowmem.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/check/mode-lowmem.c b/check/mode-lowmem.c > index 769b3141de8b..35fe1adf58e6 100644 > --- a/check/mode-lowmem.c > +++ b/check/mode-lowmem.c > @@ -1985,7 +1985,7 @@ static int check_file_extent(struct btrfs_root *root, struct btrfs_path *path, > } > } > > - *end += extent_num_bytes; > + *end = fkey.offset + extent_num_bytes; > if (!is_hole) > *size += extent_num_bytes; > >