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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 A752EC43387 for ; Sun, 13 Jan 2019 10:19:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 66C952064C for ; Sun, 13 Jan 2019 10:19:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="UXS7VtWu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726598AbfAMKTS (ORCPT ); Sun, 13 Jan 2019 05:19:18 -0500 Received: from mail-ed1-f68.google.com ([209.85.208.68]:44104 "EHLO mail-ed1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726578AbfAMKTS (ORCPT ); Sun, 13 Jan 2019 05:19:18 -0500 Received: by mail-ed1-f68.google.com with SMTP id y56so16388321edd.11 for ; Sun, 13 Jan 2019 02:19:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:from:subject:message-id:date:user-agent:mime-version :content-transfer-encoding:content-language; bh=7PZQ1PFQIeusPNOiYfiRrKLO8E8hfbTnNLyeFxm0bp0=; b=UXS7VtWuYcWLq+BTTdN+n2xEBx5VdaEG9Lu0Yj1ykNF2i0Ik3cntFXbNTWZUPhJ0fY kXtcbrEC/yrg/dOcGxrrXr73ki9oyyNlZBqvq6fHnbAduT6HzphTIc+Pwt3kLFd9iubl q/OeUhTeaWuAQ2b+XO1PXvPoNfg4v4QK7NWViDe7bQpyj0T3Vn5hN0GwS1r7qhzG7ZFE aUjPMl91b1j0aO1b5C4PfzX/xh0d40r2rlG7M1NaQCqL+0xxf/TypMum/gYYZkhqQHov zkypDy0uLTDvwRUdLsJ9aNBtE/5Rpaf63dxRwmF8RtGJ4M0FCFRDXPoVJduzlwViaNzo QjGg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:from:subject:message-id:date:user-agent :mime-version:content-transfer-encoding:content-language; bh=7PZQ1PFQIeusPNOiYfiRrKLO8E8hfbTnNLyeFxm0bp0=; b=NQ9t9e8D0liwgV1k3oIm22oX51R9YxMV5Xz0/DG/qGSn2wBqoeYcTOetmzNpjphYHW XheNpBJhEyVcWQZaDW0vsXcjTPhHTQn6xyi5ORBU2ZngmAaEob0ILMS+BcmyENC+H0xl kwr3WjmqBK/Bz3JPlAYI1wvYQOR27MO89Amp/MfMHOoUAi7z57nxXGD5oC+yPM6QOIML FaruHj/fl4hR/5o8RHfCGBr/kTevVv5R3zTJbl8tNu2UD0HocA7N24JnIpAMplJq+dvX w+sdIzgeK3lS3wAqWqWSOuavLOiEYuh7x3hWHTakauh+UGYBLYD/KzT1CHShp0LD/qx/ 1z1Q== X-Gm-Message-State: AJcUukeCcYf/vzKpoRZf9DR/iwJ6P6dhBFvu0oBPUXAlQLL3hJ3XN1l4 Q656eOXBxqxF6PzOuZr1znQksJ3U X-Google-Smtp-Source: ALg8bN5F5OyTaRr8zbIhlqkJw035YRBcaaGYxAPTifKhh8zn+8WW6XlkTNVVfBI6ouoUtrZIGbS3+Q== X-Received: by 2002:a50:b8e5:: with SMTP id l92mr18863293ede.294.1547374756145; Sun, 13 Jan 2019 02:19:16 -0800 (PST) Received: from [192.168.254.12] (ip5b42439c.dynamic.kabel-deutschland.de. [91.66.67.156]) by smtp.googlemail.com with ESMTPSA id c12sm3369286edi.52.2019.01.13.02.19.14 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 13 Jan 2019 02:19:15 -0800 (PST) To: "linux-btrfs@vger.kernel.org" From: Tobias Reinhard Subject: Retrieving Message-ID: <4472aad4-86cb-7ce2-6055-1ff8d6955969@gmail.com> Date: Sun, 13 Jan 2019 11:19:04 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.3.3 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-GB Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Hi, I want to read the complete CSUM-Tree from userspace. I tried it via the ioctl. This is what the code looks like: struct btrfs_sv2_args sv2_args; int fd = open(filename, O_RDONLY); sv2_args.key.tree_id = BTRFS_CSUM_TREE_OBJECTID; sv2_args.key.min_objectid = 0; sv2_args.key.max_objectid = -1; sv2_args.key.min_offset = 0; sv2_args.key.max_offset = -1; sv2_args.key.min_transid = 0; sv2_args.key.max_transid = -1; sv2_args.key.min_type = BTRFS_CSUM_ITEM_KEY; sv2_args.key.max_type = BTRFS_CSUM_ITEM_KEY; sv2_args.key.nr_items = -1; sv2_args.buf_size = sizeof(sv2_args.buf); ioctl(fd, BTRFS_IOC_TREE_SEARCH_V2, &sv2_args); But the device is not small and I hit the limit of the btrfs_sv2_args.buf which seems to be 16 MB. How can I get the *complete* CSUM-Tree? Limiting to offset does not work (My first idea was to do it this way and get it in chunks). Limiting to a single transid does not work as well because even one transid is larger than the limit. Kernel is 4.15. Any help would be appreciated. Best Regards Tobias