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 46662C3A59E for ; Mon, 2 Sep 2019 23:04:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 19FD221897 for ; Mon, 2 Sep 2019 23:04:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567465492; bh=6GZgqxv9ZdrRWETuEeOhYJh9DzHgCwcEevQnOpLNpuU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=n2qarMVLjUUZlfojctPBdbba8Tnus/Yu1GrSMADomZd5KZyAswYb0G+5Dyye00ZL5 muFxc3ypOZqzxrHbktiJRwf18cyIGuxOdFwbn449xVKbEeEAXfuuJ4gRzbwPx9JEO2 +VGXP924qCo/1BBi1LO8cROPBy1jU42rIZpXCTR8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727085AbfIBXEv (ORCPT ); Mon, 2 Sep 2019 19:04:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:50706 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726767AbfIBXEu (ORCPT ); Mon, 2 Sep 2019 19:04:50 -0400 Received: from localhost (unknown [104.132.0.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E79AE216C8; Mon, 2 Sep 2019 23:04:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567465490; bh=6GZgqxv9ZdrRWETuEeOhYJh9DzHgCwcEevQnOpLNpuU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=xlm3LQgQIxvu15+W1OTSs6m66X3i6ZSfdSx6wtgurwla+fwVinjVY1QaX0CcS3sEZ RROaSBjf5zbRVXp6WQhIx9H33bNQRkTKuub7PjGClfnOLsx5z+BhdAz8bsQkTOzJ4e n+DdGNL8H3QccEqOUnLPiGVp3SmpHhvxZ6S/fB/8= Date: Mon, 2 Sep 2019 16:04:49 -0700 From: Jaegeuk Kim To: Chao Yu Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, chao@kernel.org Subject: Re: [PATCH v4] f2fs: add bio cache for IPU Message-ID: <20190902230449.GD71929@jaegeuk-macbookpro.roam.corp.google.com> References: <20190219081529.5106-1-yuchao0@huawei.com> <20190901071757.GA49907@jaegeuk-macbookpro.roam.corp.google.com> <024fe351-8e25-35cd-47a7-9755498c73f4@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <024fe351-8e25-35cd-47a7-9755498c73f4@huawei.com> User-Agent: Mutt/1.8.2 (2017-04-18) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? > > struct f2fs_bio_info { > .... > struct list_head ipu_bio_list; /* track all ipu bio */ > spinlock_t ipu_bio_lock; /* protect ipu bio list */ > } > > > > >> > >> Thanks, > > . > >