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=0.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FSL_HELO_FAKE,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 E81A1C43387 for ; Mon, 17 Dec 2018 18:32:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A244A21783 for ; Mon, 17 Dec 2018 18:32:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1545071531; bh=Bxiyt5TOcJIJkJoYK7dLeb0fzlyUfhwcb+24gPm5SNE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=SFBx3xRaK2urRSL4wqIMkaJ26VtRmBJq1y5zB1aLm1KOOHNFAo1IH96nwq4NSTumG fuRIkAqL5q8CoQoYIifW1y8RcHq+XcuXycS56hL9aSci/OUvAiYAaXiTa+lqU+75ka RkarEcq5k4oax7oo0pg7RfAdSG5Ckw2YyPbWJM7w= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388852AbeLQScK (ORCPT ); Mon, 17 Dec 2018 13:32:10 -0500 Received: from mail.kernel.org ([198.145.29.99]:35330 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388003AbeLQScJ (ORCPT ); Mon, 17 Dec 2018 13:32:09 -0500 Received: from gmail.com (unknown [104.132.1.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 149A42086C; Mon, 17 Dec 2018 18:32:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1545071528; bh=Bxiyt5TOcJIJkJoYK7dLeb0fzlyUfhwcb+24gPm5SNE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=NSVyw5XpbTy8ovSwZCEx5mTh14apiTsZjgfIyqsYIMFJ/Z7UNOmBuFjRkcD9Vu9LS R40NnWZe36t9AIUV/pDVxySaOa2TbETpIB+Gkr3aixCj4Q9TL1VJaDK55jp8DiNPzE eh2j1PkNdgTMO44v4f+Tt4skGG3SME6vc1v7zPjE= Date: Mon, 17 Dec 2018 10:32:06 -0800 From: Eric Biggers To: Christoph Hellwig Cc: linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra , Linus Torvalds Subject: Re: [PATCH v2 01/12] fs-verity: add a documentation file Message-ID: <20181217183205.GA141684@gmail.com> References: <20181101225230.88058-1-ebiggers@kernel.org> <20181101225230.88058-2-ebiggers@kernel.org> <20181212091406.GA31723@infradead.org> <20181212202609.GA193967@gmail.com> <20181213202249.GA3797@infradead.org> <20181214044802.GA681@sol.localdomain> <20181217164949.GA18626@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181217164949.GA18626@infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 17, 2018 at 08:49:49AM -0800, Christoph Hellwig wrote: > > > > Given that you alread use an ioctl as the interface what is the problem > > > of passing this data through the ioctl? > > > > Do you mean pass the verity metadata in a buffer? That cannot work in general, > > because it may be too large to fit into memory. > > Have a pointer in the ioctl and do get_user_pages on it. I don't see how that helps. The Merkle tree can still be too large to fit in memory. In the worst case, it might not even fit in the address space. And I don't see how get_user_pages() helps either over just copy_from_user(); what are you proposing to do with the pages after getting them, exactly? - Eric