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=-0.8 required=3.0 tests=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 899F4C33CAE for ; Tue, 14 Jan 2020 00:14:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 670C92084D for ; Tue, 14 Jan 2020 00:14:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729271AbgANAOZ (ORCPT ); Mon, 13 Jan 2020 19:14:25 -0500 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:45697 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728641AbgANAOZ (ORCPT ); Mon, 13 Jan 2020 19:14:25 -0500 Received: from callcc.thunk.org (guestnat-104-133-0-111.corp.google.com [104.133.0.111] (may be forged)) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 00E0E7YN032266 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 13 Jan 2020 19:14:08 -0500 Received: by callcc.thunk.org (Postfix, from userid 15806) id AB74C4207DF; Mon, 13 Jan 2020 19:14:07 -0500 (EST) Date: Mon, 13 Jan 2020 19:14:07 -0500 From: "Theodore Y. Ts'o" To: Eric Biggers Cc: linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, Victor Hsieh , linux-f2fs-devel@lists.sourceforge.net Subject: Re: [PATCH v2] fs-verity: implement readahead of Merkle tree pages Message-ID: <20200114001407.GO76141@mit.edu> References: <20200106205533.137005-1-ebiggers@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200106205533.137005-1-ebiggers@kernel.org> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Jan 06, 2020 at 12:55:33PM -0800, Eric Biggers wrote: > From: Eric Biggers > > When fs-verity verifies data pages, currently it reads each Merkle tree > page synchronously using read_mapping_page(). > > Therefore, when the Merkle tree pages aren't already cached, fs-verity > causes an extra 4 KiB I/O request for every 512 KiB of data (assuming > that the Merkle tree uses SHA-256 and 4 KiB blocks). This results in > more I/O requests and performance loss than is strictly necessary. > > Therefore, implement readahead of the Merkle tree pages. Looks good. Feel free to add: Reviewed-by: Theodore Ts'o (for the ext4 and fs/verity bits)