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 A7C40EE49AF for ; Mon, 21 Aug 2023 12:21:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234808AbjHUMVM (ORCPT ); Mon, 21 Aug 2023 08:21:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48658 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232733AbjHUMVL (ORCPT ); Mon, 21 Aug 2023 08:21:11 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 33784E2; Mon, 21 Aug 2023 05:21:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=5IiWcS1pGUM8RhlF+xFAzuOei17PLjfs94NmDiNvo6g=; b=MR/QHwNqCgmOxVS7c6EPkcvTOM ewCAH+I5VyIrZrxJzwYfZLZdCgL8s90TQvZ+npslaTk64GCHlebjy/zTEFSP1XKvpvz0F1mp04dGb Q4Mw4xNqTcDxevU3YZo9ZuZG7u7901KOLFAZQFBrfJj6DTvFoLmKqeOrbe9EGAWJD80G+5oUvjC9E GE7/tDN7WYGjkchDeLjeoEXqx63p+j9VqmffpAwOVP34B8h7G2NH+m2Ijbr5WZl9m60lEmymGlSTH 3KMB/ugwe8njVx8yVWKJI7O8kZmYJA5QdxgWpCri1u728bx/fA3oJh+UCaWAdHAzd3/DRUeZhFvtJ MESTOvHA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qY3tZ-00A7pc-KQ; Mon, 21 Aug 2023 12:20:33 +0000 Date: Mon, 21 Aug 2023 13:20:33 +0100 From: Matthew Wilcox To: Jan Kara Cc: Xueshi Hu , dan.j.williams@intel.com, vishal.l.verma@intel.com, dave.jiang@intel.com, jayalk@intworks.biz, daniel@ffwll.ch, deller@gmx.de, bcrl@kvack.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.com, tytso@mit.edu, adilger.kernel@dilger.ca, miklos@szeredi.hu, mike.kravetz@oracle.com, muchun.song@linux.dev, djwong@kernel.org, akpm@linux-foundation.org, hughd@google.com, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH] fs: clean up usage of noop_dirty_folio Message-ID: References: <20230819124225.1703147-1-xueshi.hu@smartx.com> <20230821111643.5vxtktznjqk42cak@quack3> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230821111643.5vxtktznjqk42cak@quack3> Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Mon, Aug 21, 2023 at 01:16:43PM +0200, Jan Kara wrote: > On Sat 19-08-23 20:42:25, Xueshi Hu wrote: > > In folio_mark_dirty(), it will automatically fallback to > > noop_dirty_folio() if a_ops->dirty_folio is not registered. > > > > As anon_aops, dev_dax_aops and fb_deferred_io_aops becames empty, remove > > them too. > > > > Signed-off-by: Xueshi Hu > > Yeah, looks sensible to me but for some callbacks we are oscilating between > all users having to provide some callback and providing some default > behavior for NULL callback. I don't have a strong opinion either way so > feel free to add: > > Reviewed-by: Jan Kara > > But I guess let's see what Matthew thinks about this and what plans he has > so that we don't switch back again in the near future. Matthew? I was hoping Christoph would weigh in ;-) I don't have a strong feeling here, but it seems to me that a NULL ->dirty_folio() should mean "do the noop thing" rather than "do the buffer_head thing" or "do the filemap thing". In 0af573780b0b, the buffer_head default was removed. I think enough time has passed that we're OK to change what a NULL ->dirty_folio means (plus we also changed the name of ->set_page_dirty() to ->dirty_folio()) So Ack to the concept. One minor change I'd request: -bool noop_dirty_folio(struct address_space *mapping, struct folio *folio) +static bool noop_dirty_folio(struct address_space *mapping, struct folio *folio) { if (!folio_test_dirty(folio)) return !folio_test_set_dirty(folio); return false; } -EXPORT_SYMBOL(noop_dirty_folio); Please inline this into folio_mark_dirty() instead of calling it.