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=-3.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,USER_AGENT_GIT 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 AAF8AC169C4 for ; Thu, 31 Jan 2019 22:13:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A3082087F for ; Thu, 31 Jan 2019 22:13:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="UGD/7t3D" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727920AbfAaWNr (ORCPT ); Thu, 31 Jan 2019 17:13:47 -0500 Received: from mail-pl1-f195.google.com ([209.85.214.195]:33477 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726994AbfAaWNr (ORCPT ); Thu, 31 Jan 2019 17:13:47 -0500 Received: by mail-pl1-f195.google.com with SMTP id z23so2126756plo.0 for ; Thu, 31 Jan 2019 14:13:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=CcXvSDSPy9bgfIgUOH90Lcwdn7ixN1lGbyJwaRTlUHQ=; b=UGD/7t3D1sqs0Oxwzkugt+4GoJENoEhdkE18BCxu3b0cI4I8HAWmQTLcf9JCOR+KbN YHJrVVaixW/p7AliIQpmYaVsMrMzVsGZKaCBAnKnh1vxBLWug7VyP4ZBNiafbPq+mECp nEu4worV26FAaMW4F+XIGAnJX31wvNkBzgtGk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=CcXvSDSPy9bgfIgUOH90Lcwdn7ixN1lGbyJwaRTlUHQ=; b=WC+prA8JzKxIeW4JCXjKxiY2+zKYNmW9Oj44kcQQwRUZfhPXO2mKOIv/7kuNwpdv7D d75Kq4BtQVzmnwnZz3rFmAcpFylp7NACzuzJTfr4etYVbAdkOca21hh6PTg6pkQlW3w8 Vr1jKmiTbUvArdbFlnTpZnrfuvNxTTwoSf5Ud4k8fkDoBgJzQiNhCgK4ypXwFD9g1Da4 MOdpcFHgFvUdjc7b81APgWDtdLPb+p7gNbqrPhYDkBwvOU9hW3VFIG25+tkMsdi9zGK4 YgcBbZxLk+KqrItXiwEJzH+VcxSkDlm4m10j1L6Yq1qwWPbl6Zxh3uMJWnQX0avkb3aJ YBbA== X-Gm-Message-State: AJcUukeKkaJuRKB3HWS+jVyUNT8TfOZdd/xclE0klP4B5VTWzrmb75ZQ RRlg+DALJGXd0CClPtSybeUnww== X-Google-Smtp-Source: ALg8bN4Y4LTCygc9vt2/BX+K3QfXCkG+pjXFtGSxIJ5tI9AehBxJJj9uDvPFN4bg2iPrTbFIZxCf5A== X-Received: by 2002:a17:902:264:: with SMTP id 91mr36941880plc.108.1548972826464; Thu, 31 Jan 2019 14:13:46 -0800 (PST) Received: from evgreen2.mtv.corp.google.com ([2620:15c:202:201:ffda:7716:9afc:1301]) by smtp.gmail.com with ESMTPSA id z10sm7961681pfg.120.2019.01.31.14.13.45 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 31 Jan 2019 14:13:45 -0800 (PST) From: Evan Green To: Jens Axboe Cc: Gwendal Grignou , Martin K Peterson , Alexis Savery , Ming Lei , Evan Green , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RESEND PATCH 0/2] loop: Better discard for block devices Date: Thu, 31 Jan 2019 14:13:26 -0800 Message-Id: <20190131221328.85343-1-evgreen@chromium.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This series addresses some errors seen when using the loop device directly backed by a block device. The first change plumbs out the correct error message, and the second change prevents the error from occurring in many cases. The errors look like this: [ 90.880875] print_req_error: I/O error, dev loop5, sector 0 The errors occur when trying to do a discard or write zeroes operation on a loop device backed by a block device that does not support discard. Firstly, the error itself is incorrectly reported as I/O error, but is actually EOPNOTSUPP. The first patch plumbs out EOPNOTSUPP to properly report the error. The second patch prevents these errors from occurring by mirroring the discard capabilities of the underlying block device into the loop device. Before this change, discard was always reported as being supported, and the loop device simply turns around and does a discard operation on the backing device. After this change, backing block devices that do support discard will continue to work as before, and continue to get all the benefits of doing that. Backing devices that do not support discard will fail earlier, avoiding hitting the loop device at all and ultimately avoiding this error in the logs. I can also confirm that this fixes test block/003 in the blktests, when running blktests on a loop device backed by a block device. Evan Green (2): loop: Report EOPNOTSUPP properly loop: Better discard support for block devices drivers/block/loop.c | 75 ++++++++++++++++++++++++++++++-------------- 1 file changed, 52 insertions(+), 23 deletions(-) -- 2.20.1