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=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 7ED24C43381 for ; Wed, 27 Mar 2019 22:29:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4EB322082F for ; Wed, 27 Mar 2019 22:29:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="E40OAaz3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728005AbfC0W2u (ORCPT ); Wed, 27 Mar 2019 18:28:50 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:38734 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725601AbfC0W2u (ORCPT ); Wed, 27 Mar 2019 18:28:50 -0400 Received: by mail-pg1-f196.google.com with SMTP id j26so8605838pgl.5 for ; Wed, 27 Mar 2019 15:28:49 -0700 (PDT) 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=v2fLDJLohMFc1kLJ2cYvqf1Mls9WFPVr5nSai/fXAlY=; b=E40OAaz39oi24C4XipMLcKBjEeNKFf/L1kN+YE5bI5PN65aB/H6N7XmfYL7ho04V9Q IaCx6pMrH5aiiIoHfS41QfxN0Ubi2tejW5CW0kvlJYhK6mY/weVkdgxqFhbym35PSoIG W15PTUPy2w9DbF5e3SxwQy/kc/ucjY/goaVq8= 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=v2fLDJLohMFc1kLJ2cYvqf1Mls9WFPVr5nSai/fXAlY=; b=Z/ql6kzZMYlXfoKH1Tgs0sX65GPw1hoPsx+2h7bJmMP0BPNwuw0BO2WiYoZ8f8SAsj +UjNKSP7Z8IH1zHyd5qgk857Os4cz89QMDOSJu9Lqu4niATdmWP7GooSY5YIKHUQdFWM EaOqY2gkX5Bf+T7P1BTbf6n92PBQXLx19KyFugqavFiVoW1bcwvgiumqEGqQ5UPSoWqW L+r5Xfzd4k0ixfxjQryHF//T76M4zrDa+wVwMwzJ7dL5ponxfOnoCIApRuWmyKf0GQo8 7Pxjsg1xHXBNuHIfGiEM/soKv8NyQmwqJNbQ8XwXhUXaajwAoErXN+/vHIRPe7IMUZ43 TBbA== X-Gm-Message-State: APjAAAWqpliIBlK1PaH2Ocbhn/a9FWA5/SHEHA2juKj6dpij4YdQyUqO VA46FX/R1S9zXglKCob/BCI03g== X-Google-Smtp-Source: APXvYqzOYGYcyq7u9JsK1QFKXSpeOZMUFw7T+Ftd9LLv12sNrFE8EoPQZmg0PsTgkzu89Y0iNxkvvA== X-Received: by 2002:a63:1247:: with SMTP id 7mr32325872pgs.352.1553725728973; Wed, 27 Mar 2019 15:28:48 -0700 (PDT) Received: from evgreen2.mtv.corp.google.com ([2620:15c:202:201:ffda:7716:9afc:1301]) by smtp.gmail.com with ESMTPSA id p88sm36928347pfa.80.2019.03.27.15.28.47 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 27 Mar 2019 15:28:48 -0700 (PDT) From: Evan Green To: Jens Axboe , Martin K Petersen Cc: Bart Van Assche , Gwendal Grignou , Alexis Savery , Ming Lei , Evan Green , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 0/2] loop: Better discard for block devices Date: Wed, 27 Mar 2019 15:28:39 -0700 Message-Id: <20190327222841.38650-1-evgreen@chromium.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@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. Changes in v3: - Updated tags - Updated commit description Changes in v2: - Unnested error if statement (Bart) Evan Green (2): loop: Report EOPNOTSUPP properly loop: Better discard support for block devices drivers/block/loop.c | 70 ++++++++++++++++++++++++++++++-------------- 1 file changed, 48 insertions(+), 22 deletions(-) -- 2.20.1