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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6D99C433F5 for ; Tue, 14 Dec 2021 18:56:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237214AbhLNS4p (ORCPT ); Tue, 14 Dec 2021 13:56:45 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:51972 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237196AbhLNS4p (ORCPT ); Tue, 14 Dec 2021 13:56:45 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 1D1DAB81667 for ; Tue, 14 Dec 2021 18:56:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A9BD5C34600; Tue, 14 Dec 2021 18:56:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1639508202; bh=Jku8PD9u6YzING5IrsfqdnR2FiqVRc94gowzLrYhrMU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fw9jlfuXdFWgiyQU72FVE4aD8jsnJm4xaWFvKv5HNlAPPZXckXuxckbJO+7TvRYEc kftFJ8R0Wi7Qsk+YdUu7GHBp+4ScMp4jVYGudTnpDkDax06NwCNhtw3nWgsh/KqsO6 +WJnvMFbnuE0tOtQ5U6XR1raxzfSVNGaiHlhRkGnMQ4miKf0deVqu8lpRrIQcoSsh6 BX4FB+p3/JGdAxP6wAxQXYJhYtrLH66fYF5F1umuUKFpqRLhhjEsbRJTk80kgu7Ga7 +QVoFjp8/2ilTY9aosC1Ry83Icfakl2RT7sbND+bOuKAVhAMiHmXQ1G0Xc+QvoJt7J 0jM3H3lh1WEDg== Date: Tue, 14 Dec 2021 10:56:41 -0800 From: Jaegeuk Kim To: Chao Yu Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case Message-ID: References: <20210928151911.11189-1-chao@kernel.org> <65f6c366-9e5b-fe7f-7c38-061996d1882b@kernel.org> <3e653a3d-ddb9-e115-d871-3659a1ba5530@kernel.org> <96959788-73b2-6e9b-3aa7-b1e23e9da417@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <96959788-73b2-6e9b-3aa7-b1e23e9da417@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/12, Chao Yu wrote: > Ping, > > On 2021/10/30 11:02, Chao Yu wrote: > > On 2021/10/30 1:43, Jaegeuk Kim wrote: > > > On 10/29, Chao Yu wrote: > > > > Ping, > > > > > > > > On 2021/9/29 8:05, Chao Yu wrote: > > > > > On 2021/9/29 3:08, Jaegeuk Kim wrote: > > > > > > On 09/28, Chao Yu wrote: > > > > > > > In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to > > > > > > > check whethere it is overwrite case, for such case, we can skip > > > > > > > f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(), > > > > > > > which may be blocked by checkpoint() potentially. > > > > > > > > > > > > > > Signed-off-by: Chao Yu > > > > > > > --- > > > > > > >    fs/f2fs/file.c | 4 ++++ > > > > > > >    1 file changed, 4 insertions(+) > > > > > > > > > > > > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > > > > > > index 13deae03df06..51fecb2f4db5 100644 > > > > > > > --- a/fs/f2fs/file.c > > > > > > > +++ b/fs/f2fs/file.c > > > > > > > @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from) > > > > > > >            preallocated = true; > > > > > > >            target_size = iocb->ki_pos + iov_iter_count(from); > > > > > > > +        if (f2fs_overwrite_io(inode, iocb->ki_pos, > > > > > > > +                        iov_iter_count(from))) > > > > > > > +            goto write; > > > > > > > > > > > > This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte > > > > > > case. Do we have other benefit? > > > > > > > > > > f2fs_overwrite_io() will break for append write case w/ below check: > > > > > > > > > >       if (pos + len > i_size_read(inode)) > > > > >           return false; > > > > > > > > > > I guess we may only suffer double f2fs_map_blocks() for write hole > > > > > case, e.g. truncate to large size & write inside the filesize. For > > > > > this case, how about adding a condition to allow double f2fs_map_blocks() > > > > > only if write size is smaller than a threshold? > > > > > > I still don't see the benefit much to do double f2fs_map_blocks. What is the > > > problem here? > > > > There is potential hangtask happened during swapfile's writeback: > > > > - loop_kthread_worker_fn > >  - kthread_worker_fn > >   - loop_queue_work > >    - lo_rw_aio > >     - f2fs_file_write_iter > >      - f2fs_preallocate_blocks > >       - f2fs_map_blocks > >        - down_read > >         - rwsem_down_read_slowpath > >          - schedule > > > > I try to mitigate such issue by preallocating swapfile's block address and > > avoid f2fs_do_map_lock() as much as possible in swapfile's writeback path... How about checking i_blocks and i_size instead of checking the entire map? > > > > Thanks, > > > > > > > > > > > > > > > Thanks, > > > > > > > > > > > > > > > > > > + > > > > > > >            err = f2fs_preallocate_blocks(iocb, from); > > > > > > >            if (err) { > > > > > > >    out_err: > > > > > > > -- > > > > > > > 2.32.0 > > > > > > > > > > > > > > > _______________________________________________ > > > > > Linux-f2fs-devel mailing list > > > > > Linux-f2fs-devel@lists.sourceforge.net > > > > > https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Flinux-f2fs-devel&data=04%7C01%7Cchao.yu%40oppo.com%7Cbb41006c3f6d4e4d600a08d99b51cbcd%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637711597895400286%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=%2BlEAXWLpV5wGX2hL0Wj5p2qX0AqfUFI05Qiqdp8PK8g%3D&reserved=0 > > > > > > _______________________________________________ > > Linux-f2fs-devel mailing list > > Linux-f2fs-devel@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel