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=-9.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 48982C433F5 for ; Thu, 9 Sep 2021 23:51:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 21379610E9 for ; Thu, 9 Sep 2021 23:51:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229536AbhIIXwK (ORCPT ); Thu, 9 Sep 2021 19:52:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:60924 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229448AbhIIXwI (ORCPT ); Thu, 9 Sep 2021 19:52:08 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id CFE3961101; Thu, 9 Sep 2021 23:50:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1631231458; bh=DQNK28TOeDI5KHJpmRRR0Z4mB4pizyslewVn/qlEKPo=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=QRrio1fzenwWgX6Chhm0F9E6aA/MLYtTo/Gf9lc2XRxuYjHai/9/11KSIM3Hdx7Z+ 7fQ/ZDn/4Wq9jYQVu4OUoOOv+sQ3c2VmXdgtz1u+RrTZ6sRuLP/8ZD0qC7WV14Dw3c XvbN6ZZddtTBir/x6x+ZSRsBuB5JIpM3T76vl6COdqCfX/UY102tPl+mBdkkJqI3Au +l59v3N4bp3SXEQED1e/z2g+VDyw1mTdeGa8Kc0YMTKxVJPJz2TI3WyTGCQFvQT2jx D/yVRXXT+sDctnL5HeZfIwPWWxYU/DjZVopU4Hj3Nj2mfSIlGQa0N3d8UNlUCtmJqZ M6ulAt/tmp71Q== Subject: Re: [f2fs-dev] [PATCH v4] f2fs: introduce fragment allocation mode mount option To: Daeho Jeong Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com, Daeho Jeong References: <20210902172404.3517626-1-daeho43@gmail.com> <9ab17089-accc-c3a3-a5dc-007fc4eeaa20@kernel.org> <8f8e4695-4062-60c4-0f91-2a1f6a5b0a11@kernel.org> From: Chao Yu Message-ID: Date: Fri, 10 Sep 2021 07:50:57 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/9/8 2:12, Daeho Jeong wrote: > On Fri, Sep 3, 2021 at 11:45 PM Chao Yu wrote: >> >> On 2021/9/4 12:40, Daeho Jeong wrote: >>>> As a per curseg field. >>>> >>>>> Maybe, we run into the same race condition issue you told before for >>>>> fragment_remained_chunk. >>>>> Could you clarify this more? >>>> >>>> e.g. >>>> >>>> F2FS_OPTION(sbi).fs_mode = FS_MODE_FRAGMENT_FIXED_BLK >>>> fragment_chunk_size = 384 >>>> fragment_hole_size = 384 >>>> >>>> When creating hole: >>>> >>>> - f2fs_allocate_data_block >>>> - __refresh_next_blkoff >>>> chunk locates in [0, 383] of current segment >>>> seg->next_blkoff = 384 >>>> sbi->fragment_remained_chunk = 0 >>>> then we will reset sbi->fragment_remained_chunk to 384 >>>> and move seg->next_blkoff forward to 768 (384 + 384) >>>> - __has_curseg_space() returns false >>>> - allocate_segment() allocates new current segment >>>> >>>> So, for such case that hole may cross two segments, hole size may be truncated >>>> to left size of previous segment. >>> >>> First, sbi->fragment_remained_chunk should be seg->fragment_remained_chunk. >> >> Oh, correct. >> >>> I understand what you mean, so you mean we need to take the leftover >>> "hole" size over to the next segment? >>> In the example, the leftover hole size will be (384 - (512-384)). Do >>> you want to take this over to the next segment? >> >> Yes, the left 256 block-sized hole should be created before next chunk >> in next opened segment. >> > > Chao, > > Do you have any decent idea to pass the left hole size to the next > segment which will be allocated? Daeho, I guess we can record left hole size in seg->fragment_remained_hole. Thanks, > > Thanks, > >> Thanks, >> >>>