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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 6BE80C3A59E for ; Mon, 2 Sep 2019 23:35:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3B63C21897 for ; Mon, 2 Sep 2019 23:35:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567467300; bh=F9/9OqcGcQEtIqJp2H7jCpVfE3oPKJOonibTvF9TjfM=; h=Subject:To:Cc:References:From:Date:In-Reply-To:List-ID:From; b=S8CmzabRXa6UPJ81pgQcoEaNPlbu0bZmiTjh6+NGO81XganMDhKDko4DPMztg/s2w FRPKhtMrBPP1gPJ3KAtaWaYqCkMr5yoFZBEYjMUyyhls6zi3Z51nhn1KUDHIwewbQX 94OODpkSqXN8RmPnEBInjpyCNL8gcpGCeMdPnJUk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727850AbfIBXe7 (ORCPT ); Mon, 2 Sep 2019 19:34:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:33026 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726975AbfIBXe7 (ORCPT ); Mon, 2 Sep 2019 19:34:59 -0400 Received: from [192.168.0.102] (unknown [180.111.100.101]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0D7E2204EC; Mon, 2 Sep 2019 23:34:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567467297; bh=F9/9OqcGcQEtIqJp2H7jCpVfE3oPKJOonibTvF9TjfM=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=Vr1+k3iGVD46bLwn/jETtwy5lV4TZtL4Mpt9XVqsL2JZiaTIEK3zG6VKP1Jok2yJU RwT/ZeAvU7cQ42ZN3f7GvxXgvXR1SzQBfs7UQMaxSxBMtBZr4Avm1b/p+beTEgdpyb eacGXZpTyB2fnFJ3Ii/rCuYaMuzvo3OnvMLQbHeQ= Subject: Re: [PATCH v4] f2fs: add bio cache for IPU To: Jaegeuk Kim , Chao Yu Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org References: <20190219081529.5106-1-yuchao0@huawei.com> <20190901071757.GA49907@jaegeuk-macbookpro.roam.corp.google.com> <024fe351-8e25-35cd-47a7-9755498c73f4@huawei.com> <20190902230449.GD71929@jaegeuk-macbookpro.roam.corp.google.com> From: Chao Yu Message-ID: <969f59f7-a171-f303-8a4a-ee1430036b27@kernel.org> Date: Tue, 3 Sep 2019 07:34:53 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190902230449.GD71929@jaegeuk-macbookpro.roam.corp.google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-9-3 7:04, Jaegeuk Kim wrote: > On 09/02, Chao Yu wrote: >> On 2019/9/1 15:17, Jaegeuk Kim wrote: >>> On 08/31, Chao Yu wrote: >>>> On 2019/2/19 16:15, Chao Yu wrote: >>>>> @@ -1976,10 +2035,13 @@ static int __write_data_page(struct page *page, bool *submitted, >>>>> } >>>>> >>>>> unlock_page(page); >>>>> - if (!S_ISDIR(inode->i_mode) && !IS_NOQUOTA(inode)) >>>>> + if (!S_ISDIR(inode->i_mode) && !IS_NOQUOTA(inode)) { >>>>> + f2fs_submit_ipu_bio(sbi, bio, page); >>>>> f2fs_balance_fs(sbi, need_balance_fs); >>>>> + } >>>> >>>> Above bio submission was added to avoid below deadlock: >>>> >>>> - __write_data_page >>>> - f2fs_do_write_data_page >>>> - set_page_writeback ---- set writeback flag >>>> - f2fs_inplace_write_data >>>> - f2fs_balance_fs >>>> - f2fs_gc >>>> - do_garbage_collect >>>> - gc_data_segment >>>> - move_data_page >>>> - f2fs_wait_on_page_writeback >>>> - wait_on_page_writeback --- wait writeback >>>> >>>> However, it breaks the merge of IPU IOs, to solve this issue, it looks we need >>>> to add global bio cache for such IPU merge case, then later >>>> f2fs_wait_on_page_writeback can check whether writebacked page is cached or not, >>>> and do the submission if necessary. >>>> >>>> Jaegeuk, any thoughts? >>> >>> How about calling f2fs_submit_ipu_bio() when we need to do GC in the same >>> context? >> >> However it also could happen in race case: >> >> Thread A Thread B >> - __write_data_page (inode x, page y) >> - f2fs_do_write_data_page >> - set_page_writeback ---- set writeback flag in page y >> - f2fs_inplace_write_data >> - f2fs_balance_fs >> - lock gc_mutex >> - lock gc_mutex >> - f2fs_gc >> - do_garbage_collect >> - gc_data_segment >> - move_data_page >> - f2fs_wait_on_page_writeback >> - wait_on_page_writeback --- wait writeback of page y >> >> So it needs a global bio cache for merged IPU pages, how about adding a list to >> link all ipu bios in struct f2fs_bio_info? > > Hmm, I can't think of better solution than adding a list. In this case, blk_plug > doesn't work well? Only submitted bio will be taken care of plug, for our case, the bio is still pending though, I guess plug won't help. Thanks, > >> >> struct f2fs_bio_info { >> .... >> struct list_head ipu_bio_list; /* track all ipu bio */ >> spinlock_t ipu_bio_lock; /* protect ipu bio list */ >> } >> >>> >>>> >>>> Thanks, >>> . >>>