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=-3.8 required=3.0 tests=BAYES_00, 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 67B2CC433DB for ; Thu, 7 Jan 2021 18:22:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 167AB207C8 for ; Thu, 7 Jan 2021 18:22:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729082AbhAGSVw (ORCPT ); Thu, 7 Jan 2021 13:21:52 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:49937 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727058AbhAGSVw (ORCPT ); Thu, 7 Jan 2021 13:21:52 -0500 Received: from mail-wr1-f71.google.com ([209.85.221.71]) by youngberry.canonical.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1kxZuH-0007Ne-Qe for linux-block@vger.kernel.org; Thu, 07 Jan 2021 18:21:09 +0000 Received: by mail-wr1-f71.google.com with SMTP id o12so2963339wrq.13 for ; Thu, 07 Jan 2021 10:21:09 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=1yH8XJ+SsEmCmR1IemBhmlBy8uJA25p1sUW8hvVstic=; b=Lzz0hTQ9hMILZ8IBFJw2sEjZ2uKvpzwOrf2/y2kCxphg7H6X3+0cENYQEvtl7wlfmp zNaHf6qUpUs0xcz7PIBiDxlgg2b+Om/r33O3NKJJ9d+d04mSXnUZdXet8KKPvoVSa8Yr ZfB/ZBR9NCNZo4JNsj8SaNAwhtr1z1gJVHMyV/VMufITDfLB3zxNdRgLuKCM6POZeNqS dX7hfu+kIjSvL2KrPVcO9ZX1rcuRqlt5IoL1cAG8NnJAENAmZrglkb+OUUacreXScbI1 /K0hzxbiVaRAZb2m/OVmPyVVpIafC6o6Flm2NlA4HkDri2chj2x8KTUeGmuP8lj8Qfcz sXZQ== X-Gm-Message-State: AOAM531JiRQRS1YmYXn39uOPzl5zQI+DqwcT1HgfVJb/rimvfAEOXtAI jMVQ9uoq6thVPYZAT0oDL1UnrK0aU2XtWPcmCAlXadUU+hSeQTu3jFDguG8KjNw5rmygxqij1pQ cHNuzAXGyAtbt+nv7T1CQrK4B8SZ3WvMaOZNcJoliMh03mS/kNnO8oTt+ X-Received: by 2002:a1c:dc87:: with SMTP id t129mr9044714wmg.52.1610043669536; Thu, 07 Jan 2021 10:21:09 -0800 (PST) X-Google-Smtp-Source: ABdhPJz3c0mezv6YeA6BCMZ6z8n9194LaLFGX/ijTyEcry16Ek01hDA0K0VLFO5nuFasrESVg34HYsJbl4rvYNDEDHk= X-Received: by 2002:a1c:dc87:: with SMTP id t129mr9044701wmg.52.1610043669240; Thu, 07 Jan 2021 10:21:09 -0800 (PST) MIME-Version: 1.0 References: <20210105135419.68715-1-mfo@canonical.com> <20210106090758.GB3845805@T590> <20210107071055.GA3900112@T590> In-Reply-To: <20210107071055.GA3900112@T590> From: Mauricio Faria de Oliveira Date: Thu, 7 Jan 2021 15:20:58 -0300 Message-ID: Subject: Re: [PATCH v2] loop: fix I/O error on fsync() in detached loop devices To: Ming Lei Cc: Jens Axboe , linux-block@vger.kernel.org, Gabriel Krisman Bertazi , Eric Desrochers Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Jan 7, 2021 at 4:11 AM Ming Lei wrote: [snip] > OK, looks it is fine to disable writeback cache in __loop_clr_fd(). > > BTW, just wondering why don't you disable WC unconditionally in > __loop_clr_fd() or clear it in the following way because WC can be > changed via sysfs? > > if (test_bit(QUEUE_FLAG_WC, &q->queue_flags)) > blk_queue_write_cache(q, false, false); > Nice catch. Fixed that in v3. That was actually a bug, where a read-only loop device (losetup -r) that had write cache enabled via sysfs while attached, would not disable it, since it was checking only for the read-only bits, thus still suffering from the original issue. Thanks, > Thanks, > Ming > -- Mauricio Faria de Oliveira