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[2620:137:e000::1:20]) by mx.google.com with ESMTP id oj2-20020a17090b4d8200b001d28bc0e241si17716222pjb.38.2022.04.25.06.30.26; Mon, 25 Apr 2022 06:30:54 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=temperror (no key for signature) header.i=@szeredi.hu header.s=google header.b=Yj5v2QNu; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236884AbiDYIoP (ORCPT + 99 others); Mon, 25 Apr 2022 04:44:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47656 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236844AbiDYIoK (ORCPT ); Mon, 25 Apr 2022 04:44:10 -0400 Received: from mail-ej1-x632.google.com (mail-ej1-x632.google.com [IPv6:2a00:1450:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 52B617CDC0 for ; Mon, 25 Apr 2022 01:40:59 -0700 (PDT) Received: by mail-ej1-x632.google.com with SMTP id u15so28116392ejf.11 for ; Mon, 25 Apr 2022 01:40:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=szeredi.hu; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=yo7vm9yRg/QAt1cNLA0IMYEFR0QnFkwTlujuFxJ6tig=; b=Yj5v2QNu+40yHuj9V96wK5Lk2PRlgVVxr+SlafzZ7eT6mKUsJEGiQPF9w+B+5CX7oH LoXOZtHd1okc62V7YZhvvG0vy6cbqi0Nxx7zPn2IhK4P8HppahbIB3U4Np3NxBkP1N81 HkdlYhhE9SpupA1RSfERLDb5m+NekQwnEyTKE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=yo7vm9yRg/QAt1cNLA0IMYEFR0QnFkwTlujuFxJ6tig=; b=IwMzRHqua4EndDzZ5lBpo1nUZOfRY6UbtPQ11MQzWsleORm3HrTUgoGUP1Ulyry4ek YlG9vTEYwuQXvNdxzr9Pqu/H51MZmVAYKz16hQsSS85+NdwJ/RyfOtNtLEgleZOQ8rad jxK9PI93BhEYG7H7d78JdT/q+NPvjfAcvUgOeo6c1nJT1rLVs6PL+uavZEm9VCMG0vYp S5/0WWNs4bqXH2Q3fTUj4+rGWr2XI+mCsLQ9NGntg3w3kp8ZY4FwJhySvLo0E/J4hDo7 06dL3bMG2uou5NUcx0wBlw6JcRlXRDLLwqtNlZbemluVsyVjBr2U3Qgtp/47dY4iFl8u W3wA== X-Gm-Message-State: AOAM5339LGPAS9xHh5CgS1F/IPlodKryJ2JAcPnKvIlPNvvGeQlFJfoV 6m46bv1HWE3+JZo3R6onD6GbcIAJkg2ug+bPFrTOVw== X-Received: by 2002:a17:906:8982:b0:6f3:95f4:4adf with SMTP id gg2-20020a170906898200b006f395f44adfmr3637776ejc.524.1650876057869; Mon, 25 Apr 2022 01:40:57 -0700 (PDT) MIME-Version: 1.0 References: <20220408061809.12324-1-dharamhans87@gmail.com> <20220408061809.12324-2-dharamhans87@gmail.com> <2c8e61de-54da-44da-3a7b-b95eabfb29f2@ddn.com> In-Reply-To: <2c8e61de-54da-44da-3a7b-b95eabfb29f2@ddn.com> From: Miklos Szeredi Date: Mon, 25 Apr 2022 10:40:46 +0200 Message-ID: Subject: Re: [PATCH 1/1] FUSE: Allow parallel direct writes on the same file To: Bernd Schubert Cc: Dharmendra Hans , linux-fsdevel@vger.kernel.org, fuse-devel , linux-kernel@vger.kernel.org, Dharmendra Singh Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 22 Apr 2022 at 17:20, Bernd Schubert wrote: > > > > On 4/22/22 16:48, Miklos Szeredi wrote: > > On Fri, 22 Apr 2022 at 16:30, Dharmendra Hans wrote: > >> > >> On Thu, Apr 21, 2022 at 8:52 PM Miklos Szeredi wrote: > >>> > >>> On Fri, 8 Apr 2022 at 08:18, Dharmendra Singh wrote: > >>>> > > > > That's true, but I still worry... Does your workload include > > non-append extending writes? Seems to me making those run in parallel > > is asking for trouble. > > Our main use case is MPIIO for now and I don't think it first sets the > file size and would then write to these sparse files. Fixing all the > different MPI implementations including closed source stacks is probably > out of question. Okay. > Given that MPIIO also supports direct calls into its stack we also do > support that for some MPIs, but not all stacks. Direct calls bypassing > the vfs also haas it's own issues, including security. So it would be > really great if we could find a way to avoid the inode lock. > > Would you mind to share what you worry about in detail? I worry about breaking the assumption about i_size does not change if inode lock is held (exclusive of shared). Maybe that's not an issue, but we'd need to look very carefully. Thanks, Miklos