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 E85D8C433EF for ; Mon, 7 Feb 2022 19:19:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237029AbiBGTSI (ORCPT ); Mon, 7 Feb 2022 14:18:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46690 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238377AbiBGTQH (ORCPT ); Mon, 7 Feb 2022 14:16:07 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 939D8C0401DA for ; Mon, 7 Feb 2022 11:16:06 -0800 (PST) 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 dfw.source.kernel.org (Postfix) with ESMTPS id AAE1161029 for ; Mon, 7 Feb 2022 19:16:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 03219C004E1; Mon, 7 Feb 2022 19:16:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644261365; bh=FX8ZhpIlZF+4RHH0iTaQPztnxFU3gZjZlumdpdlOJzg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nH2L/yXFXkWChhV3VCclL8E2NfMRs46hGDZfdUS+NeLk26ueq9blVUKofZcMxyJuv 4XSqNwJkk+WwgY36/WpUrWh4l08REKDiDGmOkITBFVgrOU1hLnvfQu6XYh5Y7pTpyB F7wIc2ybYsHimr8PEUjZt4aB44qTn40Bx2yZ9IUZxFYfx/kbZv+BR3SDHq9ZQ4c+rg 4+Y613Qu9HMtCaNlXYe/hQ+VIyrmoglIWRABM9RlbME4zgJ926w4K3T6Tg6OEyI8CX RlGyGXC6RTViKQ3aj80lNq4WqY8wlPQpNvTw9TU4oENNPiHPRf70MUg5/Em7N818wr PfXLlO3vAFlKg== Date: Mon, 7 Feb 2022 11:16:03 -0800 From: Jaegeuk Kim To: Chao Yu Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] f2fs: skip f2fs_preallocate_blocks() for overwrite case Message-ID: References: <20220204091005.49407-1-chao@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220204091005.49407-1-chao@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/04, Chao Yu wrote: > There is potential hangtask happened during swapfile's writeback: > > - loop_kthread_worker_fn - do_checkpoint > - kthread_worker_fn > - loop_queue_work > - lo_rw_aio > - f2fs_file_write_iter > - f2fs_preallocate_blocks > - f2fs_map_blocks > - down_write > - down_read > - rwsem_down_read_slowpath > - schedule > > One cause is f2fs_preallocate_blocks() will always be called no matter > the physical block addresses are allocated or not. > > This patch tries to check whether block addresses are all allocated with > i_size and i_blocks of inode, it's rough because blocks can be allocated > beyond i_size, however, we can afford skipping block preallocation in this > condition since it's not necessary to do preallocation all the time. > > Signed-off-by: Chao Yu > --- > v2: > - check overwrite case with i_size and i_blocks roughly. > fs/f2fs/file.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > index cfdc41f87f5d..09565d10611d 100644 > --- a/fs/f2fs/file.c > +++ b/fs/f2fs/file.c > @@ -4390,6 +4390,16 @@ static int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *iter, > int flag; > int ret; > > + /* > + * It tries to check whether block addresses are all allocated, > + * it's rough because blocks can be allocated beyond i_size, > + * however, we can afford skipping block preallocation since > + * it's not necessary all the time. > + */ > + if (F2FS_BLK_ALIGN(i_size_read(inode)) == > + SECTOR_TO_BLOCK(inode->i_blocks)) Do we count i_blocks only for data? > + return 0; > + > /* If it will be an out-of-place direct write, don't bother. */ > if (dio && f2fs_lfs_mode(sbi)) > return 0; > -- > 2.32.0