Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751230AbdH1NWR (ORCPT ); Mon, 28 Aug 2017 09:22:17 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:5027 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751152AbdH1NWQ (ORCPT ); Mon, 28 Aug 2017 09:22:16 -0400 Subject: Re: [PATCH] f2fs: discard small invalid blocks in current active segments To: Chao Yu , , , CC: , , , , References: <1503751772-158812-1-git-send-email-yunlong.song@huawei.com> From: Yunlong Song Message-ID: <61d97244-c4e5-0008-ab30-fc52a05e0b24@huawei.com> Date: Mon, 28 Aug 2017 21:21:29 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.111.220.140] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A0B0208.59A418FC.0141,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 15448908f034fea056a27799911d6ef6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1474 Lines: 47 How? Can the invalid blocks of file A be discarded, if file B is alive all the time and fggc_threshold is 507 ? On 2017/8/28 17:59, Chao Yu wrote: > On 2017/8/26 20:49, Yunlong Song wrote: >> 1. write file A with 5 blocks to current empty active segment >> 2. remove file A >> 3. write checkpoint >> 4. write file B with 507 blocks to the same active segment >> >> If file B is alive all the time, the blocks used by file A will never be >> discarded. So current active segment should also be treated as a candidate >> for small discards. > I don't think that would be a big issue, since there will not be any freezing > log headers, once log header moves, later invalid blocks could be discarded. > > Thanks, > >> Signed-off-by: Yunlong Song >> --- >> fs/f2fs/segment.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c >> index 8375257..a2e7c8f 100644 >> --- a/fs/f2fs/segment.c >> +++ b/fs/f2fs/segment.c >> @@ -1339,7 +1339,9 @@ static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc, >> return false; >> >> if (!force) { >> - if (!test_opt(sbi, DISCARD) || !se->valid_blocks || >> + if (!test_opt(sbi, DISCARD) || >> + (!se->valid_blocks && >> + !IS_CURSEG(sbi, cpc->trim_start)) || >> SM_I(sbi)->dcc_info->nr_discards >= >> SM_I(sbi)->dcc_info->max_discards) >> return false; >> > > . > -- Thanks, Yunlong Song