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 C1B92C433EF for ; Tue, 22 Mar 2022 02:50:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235620AbiCVCvk (ORCPT ); Mon, 21 Mar 2022 22:51:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38306 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235577AbiCVCvj (ORCPT ); Mon, 21 Mar 2022 22:51:39 -0400 Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8FEF64F9DE for ; Mon, 21 Mar 2022 19:50:12 -0700 (PDT) Received: by mail-pj1-x102a.google.com with SMTP id mr5-20020a17090b238500b001c67366ae93so1182679pjb.4 for ; Mon, 21 Mar 2022 19:50:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=B5PNzgEcp6v2BJNLNi+4zg0srfxRDwNVS+rv1yOEHhM=; b=vj3/jlOn1LkH2HdLUqdcTTxwa6jaGU2l8TDVIsP3ihBANaw05026klx9iMCtyYSnAR pXqdnfaewG5sMETf6wwYujb/6IZQAme5CwOSX+dVqEWmrGnMiY0GVZQ7YKeMS7BSoEI5 GVU4SpDC0dHxyunR556FFjyY9y1i26DC+qMReDfFfWsXNlzkgmTUSW6vOhqiEb2dJynP a0WuKlUCBtiEe3lfbw3DsYEGcIWRepZkrNmA8sVzty4AUWrIXDP7urA9XnWx1ZZA2wxJ IKv2E39Kvex9JT0z3kxxnoIMHwzalgfAxiE1ejEPlH7TNHqr7oLkMf2XKlXyR/Prt4b2 oLQw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=B5PNzgEcp6v2BJNLNi+4zg0srfxRDwNVS+rv1yOEHhM=; b=N9TruOw7ScvRVtN0sNpseVbG39VCyZCkEbOtg8YvID6z6klw5vVqWgQmPNji2kn05t U31vqIuL/xPQcOv6gYvI8LJHvBCsB0n87dPdWZVcJgb+3sBs9+Q+qSS0q/YewC46ktnS u9kjNFsPAjVtYmxnjH7eV+0PQh7fesJlOAl7DFLhSCl2otQXnCdomWGgO3SXfq9Rn5Vg mF+RJtdGY6KA4jxCMuo064uwxFlkXI+vsas+5ChYZb93WaII9LullGI+VZ1wvPdlnMbR 8xR90XzJ31RqSydKNoJNQWRwlujgnyvudIbpNCcS9HsVSQ0c117Vo4pu1Jkp5JMZuUS2 YRXQ== X-Gm-Message-State: AOAM530IzttJ90HcFv5uYv5rIYAKCgTomSnRKuKKkPWVSwdRvOXNch89 D8g7xF/xowkGo/JIEcg9QXUJYP5AZDbRboX2 X-Google-Smtp-Source: ABdhPJxnuAF867GdXqEmx0nbN2+jkI3LMCHKy+NOZAM2KjlwF9N/SMN/gmIFMS5eSeojO0P29YG02A== X-Received: by 2002:a17:90a:a591:b0:1bc:8015:4c9e with SMTP id b17-20020a17090aa59100b001bc80154c9emr2393380pjq.154.1647917411931; Mon, 21 Mar 2022 19:50:11 -0700 (PDT) Received: from [192.168.1.100] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id c18-20020a056a000ad200b004f0f9696578sm23169678pfl.141.2022.03.21.19.50.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 21 Mar 2022 19:50:11 -0700 (PDT) Message-ID: Date: Mon, 21 Mar 2022 20:50:10 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH 1/2] fs: remove kiocb.ki_hint Content-Language: en-US To: Matthew Wilcox Cc: Christoph Hellwig , linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <20220308060529.736277-1-hch@lst.de> <20220308060529.736277-2-hch@lst.de> <164678732353.405180.15951772868993926898.b4-ty@kernel.dk> From: Jens Axboe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 3/21/22 8:45 PM, Matthew Wilcox wrote: > On Mon, Mar 21, 2022 at 08:13:10PM -0600, Jens Axboe wrote: >> On 3/8/22 5:55 PM, Jens Axboe wrote: >>> On Tue, 8 Mar 2022 07:05:28 +0100, Christoph Hellwig wrote: >>>> This field is entirely unused now except for a tracepoint in f2fs, so >>>> remove it. >>>> >>>> >>> >>> Applied, thanks! >>> >>> [1/2] fs: remove kiocb.ki_hint >>> commit: 41d36a9f3e5336f5b48c3adba0777b8e217020d7 >>> [2/2] fs: remove fs.f_write_hint >>> commit: 7b12e49669c99f63bc12351c57e581f1f14d4adf >> >> Upon thinking about the EINVAL solution a bit more, I do have a one >> worry - if you're currently using write_hints in your application, >> nobody should expect upgrading the kernel to break it. It's a fine >> solution for anything else, but that particular point does annoy me. > > But if your application is run on an earlier kernel, it'll get > -EINVAL. So it must already be prepared to deal with that? Since support wasn't there, it's not unreasonable to expect that an application was written on a newer kernel. Might just be an in-house or application thing, who knows? But the point is that upgrading from 5.x to 5.x+1, nobody should expect their application to break. And it will with this change. If you downgrade a kernel and a feature didn't exist back then, it's reasonable to expect that things may break. Maybe this is being overly cautious, but... As a matter of principle, it's unquestionably wrong. We can just let Linus make the decision here, arming him with the info he needs to make it in terms of hardware support. I'll write that up in the pull request. -- Jens Axboe