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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 0B8AFC55178 for ; Fri, 23 Oct 2020 11:13:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BB64E24631 for ; Fri, 23 Oct 2020 11:13:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Ie9QJ2wq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S462803AbgJWLNW (ORCPT ); Fri, 23 Oct 2020 07:13:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55452 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S462757AbgJWLNV (ORCPT ); Fri, 23 Oct 2020 07:13:21 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B23D3C0613CE; Fri, 23 Oct 2020 04:13:20 -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=L5+0ZOmshEWGRjYQbZQfyKQ/jkbENBN4GZDIbl9am3E=; b=Ie9QJ2wqfW+8LSUdxH/tSg8hAa 8C2mIC2GrZ8PI1MXKvN9BsfRilt8jYdEkGxyFOfAVDvy6Td3hQ9uBq6ez/h9E2ABxawDSJiOLHdJI LsZGNhEw0cC/ka2DrAdzFFZOie+px6AWbWK1jzCBTuyNuGJIbDc7Ua0tb1SKyYrwGa4R7W5BG1jO8 lxiEoi4nFgMohtN2CS2nX2Xcq7PIeN+Dvq+4Kp4WllzbqLpZqVP7tQsfMfzuy3e8gjTCMhW6FI+3k 4bz8a/7pem0jnI9l+DNScgPNKZTBfOKlV0f3hYQ2enHlqjYNexs64ubBaoTEtoMg6kzVaSt0292L4 yhh0jICQ==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kVv09-0005sV-5b; Fri, 23 Oct 2020 11:12:53 +0000 Date: Fri, 23 Oct 2020 12:12:53 +0100 From: "hch@infradead.org" To: Hannes Reinecke Cc: "hch@infradead.org" , Mike Snitzer , "jack@suse.cz" , "gustavo@embeddedor.com" , "linux-mm@kvack.org" , device-mapper development , "pavel@ucw.cz" , "steve@sk2.org" , "osandov@fb.com" , Alasdair G Kergon , "bvanassche@acm.org" , "Darrick J. Wong" , "len.brown@intel.com" , "linux-pm@vger.kernel.org" , "ming.lei@redhat.com" , "linux-block@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "viro@zeniv.linux.org.uk" , Sergei Shtepa , "koct9i@gmail.com" , "axboe@kernel.dk" , Damien Le Moal , Johannes Thumshirn , "rjw@rjwysocki.net" , "linux-kernel@vger.kernel.org" , "linux-xfs@vger.kernel.org" , "tj@kernel.org" , "akpm@linux-foundation.org" Subject: Re: [dm-devel] [PATCH 0/2] block layer filter and block device snapshot module Message-ID: <20201023111253.GA22468@infradead.org> References: <71926887-5707-04a5-78a2-ffa2ee32bd68@suse.de> <20201021141044.GF20749@veeam.com> <20201022094402.GA21466@veeam.com> <20201022135213.GB21466@veeam.com> <20201022151418.GR9832@magnolia> <20201023091346.GA25115@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Oct 23, 2020 at 12:31:05PM +0200, Hannes Reinecke wrote: > My thoughts went more into the direction of hooking into ->submit_bio, > seeing that it's a NULL pointer for most (all?) block drivers. > > But sure, I'll check how the interposer approach would turn out. submit_bio is owned by the underlying device, and for a good reason stored in a const struct..