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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 23A10C433EF for ; Fri, 29 Oct 2021 17:43:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0EF906108F for ; Fri, 29 Oct 2021 17:43:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230119AbhJ2Rp6 (ORCPT ); Fri, 29 Oct 2021 13:45:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:56948 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230075AbhJ2Rp4 (ORCPT ); Fri, 29 Oct 2021 13:45:56 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 92B7A61040; Fri, 29 Oct 2021 17:43:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1635529407; bh=rsaoqoFMJRkFW8HbI1/g5SAhlNrxOJ2ODlLw2rtjQVw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TWI+jjY0ML1p9Nw0Dtl1KOyq5HJqk87BImQU70Cl4KdrO+WFa4/1eXJxAHGo0I3B1 P/NvnMbfHSuOP2R46KsW2PdDpFH+Ejzgy2WcXm8VdW+MoO8hklvBq403DcDAKYxGDV mHxsKA5ZC4yWlQanMq8jCrM8qWeXEku+Kg22esQqwvs1SMJSMjIlaZ5R1n656tYy3b Lx5l4t9du+GMlRyUCeJsgwxECQ88Oq1feTNOL4xZBJ0gQ0YwGpafGfCWUZB7L8YPix ksi7CCHYMIS34CwUiqSHNy3RC+DlXPwoPjbQWjjzyX44QJPRpzSWY2aJhdtHO45LE4 YcDzGXpMmMTQA== Date: Fri, 29 Oct 2021 10:43:26 -0700 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> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? > > > > 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%7C421c06812eba4f922b0908d982dcdcc5%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637684707374940190%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=u22eEWDAPaAZCyISyjTUOtQDLDuyKxTnNCI3eSwwWro%3D&reserved=0