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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 ACFFAC433E6 for ; Wed, 10 Mar 2021 08:38:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8259164FC0 for ; Wed, 10 Mar 2021 08:38:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229546AbhCJIhr (ORCPT ); Wed, 10 Mar 2021 03:37:47 -0500 Received: from verein.lst.de ([213.95.11.211]:35158 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232289AbhCJIh0 (ORCPT ); Wed, 10 Mar 2021 03:37:26 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 5F87968B05; Wed, 10 Mar 2021 09:37:23 +0100 (CET) Date: Wed, 10 Mar 2021 09:37:23 +0100 From: Christoph Hellwig To: Matthew Wilcox Cc: Christoph Hellwig , Al Viro , Andrew Morton , Daniel Vetter , Nadav Amit , "VMware, Inc." , "Michael S. Tsirkin" , David Hildenbrand , Minchan Kim , Nitin Gupta , Jason Gunthorpe , Alex Williamson , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, virtualization@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: make alloc_anon_inode more useful Message-ID: <20210310083723.GC5217@lst.de> References: <20210309155348.974875-1-hch@lst.de> <20210310040545.GM3479805@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210310040545.GM3479805@casper.infradead.org> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Mar 10, 2021 at 04:05:45AM +0000, Matthew Wilcox wrote: > On Tue, Mar 09, 2021 at 04:53:39PM +0100, Christoph Hellwig wrote: > > this series first renames the existing alloc_anon_inode to > > alloc_anon_inode_sb to clearly mark it as requiring a superblock. > > > > It then adds a new alloc_anon_inode that works on the anon_inode > > file system super block, thus removing tons of boilerplate code. > > > > The few remainig callers of alloc_anon_inode_sb all use alloc_file_pseudo > > later, but might also be ripe for some cleanup. > > On a somewhat related note, could I get you to look at > drivers/video/fbdev/core/fb_defio.c? > > As far as I can tell, there's no need for fb_deferred_io_aops to exist. > We could just set file->f_mapping->a_ops to NULL, and set_page_dirty() > would do the exact same thing this code does (except it would get the > return value correct). > But maybe that would make something else go wrong that distinguishes > between page->mapping being NULL and page->mapping->a_ops->foo being NULL? I can't find any place in the kernel that treats a NULL aops different from not having the method it is looking for. > Completely untested patch ... the patch looks mostly good to me. > } > -#ifdef CONFIG_FB_DEFERRED_IO > - if (info->fbdefio) > - fb_deferred_io_open(info, inode, file); > -#endif > + file->f_mapping->a_ops = NULL; But I'd also skip this. Drivers generally do not set aops, but if they do a funtion like this really should not override it. This will require an audit of the callers, though.