From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from szxga04-in.huawei.com ([45.249.212.190]:5476 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751152AbdH1KAT (ORCPT ); Mon, 28 Aug 2017 06:00:19 -0400 Subject: Re: [PATCH] f2fs: discard small invalid blocks in current active segments To: Yunlong Song , , , CC: , , , , References: <1503751772-158812-1-git-send-email-yunlong.song@huawei.com> From: Chao Yu Message-ID: Date: Mon, 28 Aug 2017 17:59:52 +0800 MIME-Version: 1.0 In-Reply-To: <1503751772-158812-1-git-send-email-yunlong.song@huawei.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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; >