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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EA423E9271B for ; Thu, 5 Oct 2023 17:18:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229891AbjJERSg (ORCPT ); Thu, 5 Oct 2023 13:18:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46090 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230466AbjJERRt (ORCPT ); Thu, 5 Oct 2023 13:17:49 -0400 Received: from mail-pf1-f176.google.com (mail-pf1-f176.google.com [209.85.210.176]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 86D8F271F; Thu, 5 Oct 2023 10:10:48 -0700 (PDT) Received: by mail-pf1-f176.google.com with SMTP id d2e1a72fcca58-694f3444f94so1023701b3a.2; Thu, 05 Oct 2023 10:10:48 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696525848; x=1697130648; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Mau3Ytqwy7TZu9wwYpopAHbH4XlNKRL4d1UxE9xBpfw=; b=an0tRdeZR8L82BbTIXPQpuym7qXuraJsgB6jec+r9avljTJrywnf5bxAvKZvN+RaFL 1IOxRUHqDNqO0HjCx8a4Cn++qr6f8C47fM+zlrpwQOwxDXF7LKKrlLmYLBLruad+e/4w yChHYbMonF+VPwbrN8Fv7OzbrOyrdKowNaG5ln++F0oPOg9UHpD6YMyt5v2N+DPFyLCx ToR0Fo7Of7qWsS8yxefsnzvb7UWu/QF/KCAywDdJ6t+PbUE5qIil+SyKPbpF4rLLXop7 ye/Cp4TBjuTt/V45gJb5nC4VcYuA2olgH2xnew0UphcDHDla+vzsqyLddhGPRo/QZ75n 9tBg== X-Gm-Message-State: AOJu0YzA3AHjB+UzjywzPsjodr4qGObGPpdsdruSfWx05rf+rt4gxe+g fGX9KWE9PC4KgtOK8CNnEvA= X-Google-Smtp-Source: AGHT+IGnVdp8oICK4V8pUUfksO9nmUjiTQt7WLAzT5URUjUrgm7Kl0ihNxBLzaBBJ2yggv4nt+XNYg== X-Received: by 2002:a05:6a00:1410:b0:68b:eb3d:8030 with SMTP id l16-20020a056a00141000b0068beb3d8030mr6024179pfu.1.1696525847811; Thu, 05 Oct 2023 10:10:47 -0700 (PDT) Received: from ?IPV6:2620:15c:211:201:ca3e:70ef:bad:2f? ([2620:15c:211:201:ca3e:70ef:bad:2f]) by smtp.gmail.com with ESMTPSA id t16-20020a63b250000000b00565eb4fa8d1sm1641495pgo.16.2023.10.05.10.10.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 05 Oct 2023 10:10:47 -0700 (PDT) Message-ID: Date: Thu, 5 Oct 2023 10:10:45 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 10/21] block: Add fops atomic write support Content-Language: en-US To: "Martin K. Petersen" Cc: John Garry , axboe@kernel.dk, kbusch@kernel.org, hch@lst.de, sagi@grimberg.me, jejb@linux.ibm.com, djwong@kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org, chandan.babu@oracle.com, dchinner@redhat.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, tytso@mit.edu, jbongio@google.com, linux-api@vger.kernel.org References: <20230929102726.2985188-1-john.g.garry@oracle.com> <20230929102726.2985188-11-john.g.garry@oracle.com> <17ee1669-5830-4ead-888d-a6a4624b638a@acm.org> <5d26fa3b-ec34-bc39-ecfe-4616a04977ca@oracle.com> <34c08488-a288-45f9-a28f-a514a408541d@acm.org> From: Bart Van Assche In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On 10/4/23 11:17, Martin K. Petersen wrote: > > Hi Bart! > >> In other words, also for the above example it is guaranteed that >> writes of a single logical block (512 bytes) are atomic, no matter >> what value is reported as the ATOMIC TRANSFER LENGTH GRANULARITY. > > There is no formal guarantee that a disk drive sector > read-modify-write operation results in a readable sector after a > power failure. We have definitely seen blocks being mangled in the > field. Aren't block devices expected to use a capacitor that provides enough power to handle power failures cleanly? How about blacklisting block devices that mangle blocks if a power failure occurs? I think such block devices are not compatible with journaling filesystems nor with log-structured filesystems. Thanks, Bart.