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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 3DBE6ECDFB0 for ; Fri, 13 Jul 2018 03:29:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E79A620870 for ; Fri, 13 Jul 2018 03:28:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E79A620870 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387888AbeGMDld (ORCPT ); Thu, 12 Jul 2018 23:41:33 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:55779 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2387722AbeGMDld (ORCPT ); Thu, 12 Jul 2018 23:41:33 -0400 Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 8CD5B7C89A07E; Fri, 13 Jul 2018 11:28:53 +0800 (CST) Received: from [127.0.0.1] (10.111.220.140) by DGGEMS414-HUB.china.huawei.com (10.3.19.214) with Microsoft SMTP Server id 14.3.382.0; Fri, 13 Jul 2018 11:28:48 +0800 Subject: Re: [PATCH 2/5] f2fs: clear the remaining prefree_map of the section To: Chao Yu , , , CC: , , , , , References: <1531408170-45758-1-git-send-email-yunlong.song@huawei.com> <1531408170-45758-3-git-send-email-yunlong.song@huawei.com> From: Yunlong Song Message-ID: <75dc9cad-8166-82c5-e085-88c9623f5c5e@huawei.com> Date: Fri, 13 Jul 2018 11:28:22 +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 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org round 1: section bitmap : 1 1 1 1 1, all valid, prefree_map: 0 0 0 0 0 then rm data block NO.2, block NO.2 becomes invalid, prefree_map: 0 0 1 0 0 write_checkpoint: section bitmap: 1 1 0 1 1, prefree_map: 0 0 0 0 0, prefree of NO.2 is cleared, and no discard issued round2: rm data block NO.0, NO.1, NO.3, NO.4 all invalid, but prefree bit of NO.2 is set and cleared in round1, then prefree_map: 1 1 0 1 1 write_checkpoint: section bitmap: 0 0 0 0 0, prefree_map: 0 0 0 1 1, no valid blocks of this section, so discard issued but this time prefree bit of NO.3 and NO.4 is skipped... round3: write_checkpoint: section bitmap: 0 0 0 0 0, prefree_map: 0 0 0 1 1 - > 0 0 0 0 0, no valid blocks of this section, so discard issued this time prefree bit of NO.3 and NO.4 is cleared, but the discard of this section is sent again... On 2018/7/13 11:13, Chao Yu wrote: > On 2018/7/12 23:09, Yunlong Song wrote: >> For the case when sbi->segs_per_sec > 1, take section:segment = 5 for >> example, if the section prefree_map is ...previous section | current >> section (1 1 0 1 1) | next section..., then the start = x, end = x + 1, >> after start = start_segno + sbi->segs_per_sec, start = x + 5, then it >> will skip x + 3 and x + 4, but their bitmap is still set, which will >> cause duplicated f2fs_issue_discard of this same section in the next >> write_checkpoint, so fix it. > I didn't get it, if # 2 segment is not prefree state, so it still has valid > blocks there, so we won't issue discard due to below condition, right? > > if (!IS_CURSEC(sbi, secno) && > !get_valid_blocks(sbi, start, true)) > > Thanks, > >> Signed-off-by: Yunlong Song >> --- >> fs/f2fs/segment.c | 19 +++++++++++++++++-- >> 1 file changed, 17 insertions(+), 2 deletions(-) >> >> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c >> index 47b6595..fd38b61 100644 >> --- a/fs/f2fs/segment.c >> +++ b/fs/f2fs/segment.c >> @@ -1684,8 +1684,23 @@ void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi, >> start = start_segno + sbi->segs_per_sec; >> if (start < end) >> goto next; >> - else >> - end = start - 1; >> + else { >> + start_segno = start; >> + >> + while (1) { >> + start = find_next_bit(prefree_map, start_segno, >> + end + 1); >> + if (start >= start_segno) >> + break; >> + end = find_next_zero_bit(prefree_map, start_segno, >> + start + 1); >> + for (i = start; i < end; i++) >> + clear_bit(i, prefree_map); >> + dirty_i->nr_dirty[PRE] -= end - start; >> + } >> + >> + end = start_segno - 1; >> + } >> } >> mutex_unlock(&dirty_i->seglist_lock); >> >> > > . > -- Thanks, Yunlong Song