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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 6C2EAC43387 for ; Wed, 19 Dec 2018 07:11:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3A6C821852 for ; Wed, 19 Dec 2018 07:11:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="FKUYdz2A" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728249AbeLSHLw (ORCPT ); Wed, 19 Dec 2018 02:11:52 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:35420 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726716AbeLSHLv (ORCPT ); Wed, 19 Dec 2018 02:11:51 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=GbFsH92F8LYgPzCETeldoQ5SjmPUN4loEk5ARz1d5Lo=; b=FKUYdz2A7lD/wcAmN4VQB7ReZ Lgl8H/8o3qxyTy4Qrd0kzjFNfZgwEW/4A17spUy06+j1ZmKiCMGm/JqEVzULLFNVD6YgyV6A/T/wC fwJ14RzGklfd0d/VUx0k4aci1UnU9BMsLzEb6kvjWEKQqQ1Zf5xIb+E7pMp0xx6hs54HEmL8DbQHE 1KnXMPVGy4uoDSAMMFLpNVzxA6VH3qL69thOxAepoM9kB++VCMw9vauMuCiVtxdbYi/upISDr6vgt 2210gFBDEKBLzEst+J+w5wsWB+JVGqQlzfrwuOxPJT03+uI6708Oj4/J3MYcFl400o/mCRvvjJHF0 SyntpkbtA==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gZW1F-0002i2-MI; Wed, 19 Dec 2018 07:11:49 +0000 Date: Tue, 18 Dec 2018 23:11:49 -0800 From: Christoph Hellwig To: "Darrick J. Wong" Cc: Eric Biggers , Christoph Hellwig , 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: <20181219071149.GB2628@infradead.org> 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> <20181217200039.GD8111@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181217200039.GD8111@magnolia> User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Mon, Dec 17, 2018 at 12:00:39PM -0800, Darrick J. Wong wrote: > FWIW, if I were (hypothetically) working on an xfs implementation, I > likely would have settled on passing a reference to a merkle tree > through a (fd, length) pair, because that allows us plenty of options > on the back end: > > b) we could remap the tree into a new inode fork for merkle trees, or > a) remap it as posteof blocks like ext4/f2fs does, or > c) remap the blocks into the attribute fork as an (unusually large) > extended attribute value. > > If the merkle_fd isn't on the same filesystem as the fd we could at > least use generic_copy_file_range (i.e. page cache copying) to land the > merkle tree wherever we want. I think the fd would have to be on the same fs for this interface to make sense. But it could be an O_TMPFILE one. And given that ext4 already supports a variant of swapext this interface should also work with the existing ext4 on disk format.