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=-5.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 CD437C388F9 for ; Tue, 17 Nov 2020 03:17:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8638E24694 for ; Tue, 17 Nov 2020 03:17:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="YfWZvwi0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726339AbgKQDRe (ORCPT ); Mon, 16 Nov 2020 22:17:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51176 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726205AbgKQDRe (ORCPT ); Mon, 16 Nov 2020 22:17:34 -0500 Received: from mail-pg1-x543.google.com (mail-pg1-x543.google.com [IPv6:2607:f8b0:4864:20::543]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 25619C0613CF; Mon, 16 Nov 2020 19:17:34 -0800 (PST) Received: by mail-pg1-x543.google.com with SMTP id 34so11804623pgp.10; Mon, 16 Nov 2020 19:17:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:cc:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=6w6Y+KqzYbUwOj4A2p9Oz5OKTpIjMcQwiYg01iziPDg=; b=YfWZvwi04XQpIu88S35NvFhkwZGp3RXqeam0pIp4LMSrQLR9hpxk6Vt0AUwO+kYgzy 8sh6m6J+8VM9FQZEbEI/eMTe9SWwNinhS+3w5Pz7xktWA9SdSeKXv6NtupePZwX4YP6b 9Uuu/h4oQ2cYzaiOuZdsN8SOGixniVnP8AmslVlqtcRd1RH+4TszkR3yRwpqGZj5Dhal QytFRpteTeBUU4rOkeLaF5CXlKJSJFi6UjTpseAlI17oZtgn0nJyvVHcuz9XoCvh9vir Sxn6n1dwGYXGCfTdE9dGKFFrUVN5D0BeAUNJ3IKrO451MibByObzTtptHxJ4TjeQQzhw H07A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:cc:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=6w6Y+KqzYbUwOj4A2p9Oz5OKTpIjMcQwiYg01iziPDg=; b=gF/jB81kYxmk5f1I4jwh5g4ZqsgyJ99tm7JKVQ8vfZ7PTW/J2yRNvugqDJS4uFcq0b nIr8d2S2qhNXnS8SfTWc3XS3iyNj4HntJzUr85CIUc/9+5+clKWbmjidtcRsCmqA3Kcl vTTMqX4kiRJ8AdBIzBDQRI/H6wuyxI/vZc8bSjufhH5PZhhEFhzQ1yRSPnhBUjNhWpPf ZXZebCh1b4m/8iSMi6IRz1z5bGIQLWOaeY0uLb45r9KJiiUUoiLLC7akR8UaLfQj1gj2 3ZxZ5zFVidUnef2fbIvqLfDUQGfgjcpXr7AP/1MaA16X4i28GnWxQufr4Wlc20Ly6J15 HpsQ== X-Gm-Message-State: AOAM530p+gmIaYzt7mPIq56igiulc94wbKewuZpu9gG9wtIY64ogPF8w pxknsR4Lcb2Kz/kNJdY6Vw== X-Google-Smtp-Source: ABdhPJykU1tkk71gKf6j4um/95973o5WKsvcw7cpJ6eI6Gdfq+Q9J1aBfsjMElSOlmc3YNE4Z/pMNQ== X-Received: by 2002:a62:e516:0:b029:156:3b35:9423 with SMTP id n22-20020a62e5160000b02901563b359423mr16121769pff.19.1605583053709; Mon, 16 Nov 2020 19:17:33 -0800 (PST) Received: from [10.76.131.47] ([103.7.29.7]) by smtp.gmail.com with ESMTPSA id t26sm21393757pfl.72.2020.11.16.19.17.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Nov 2020 19:17:33 -0800 (PST) Subject: Re: [PATCH] btrfs: remove the useless value assignment in block_rsv_release_bytes To: dsterba@suse.cz, dsterba@suse.com References: <1605422363-14947-1-git-send-email-kaixuxia@tencent.com> <20201116151512.GJ6756@twin.jikos.cz> From: kaixuxia Cc: clm@fb.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, Kaixu Xia Message-ID: <104c5965-fbbe-b306-e835-5f2bbf60aa7f@gmail.com> Date: Tue, 17 Nov 2020 11:17:17 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.4.3 MIME-Version: 1.0 In-Reply-To: <20201116151512.GJ6756@twin.jikos.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/11/16 23:15, David Sterba wrote: > On Sun, Nov 15, 2020 at 02:39:23PM +0800, xiakaixu1987@gmail.com wrote: >> From: Kaixu Xia >> >> The variable qgroup_to_release is overwritten by the following if/else >> statement before it is used, so this assignment is useless. Remove it. > > Again this lacks explanation why removing it is correct. > Actually this assignment is redundant because the variable qgroup_to_release has been overwritten before it is used. The logic like this, static u64 block_rsv_release_bytes(...) { ... if (num_bytes == (u64)-1) { num_bytes = block_rsv->size; qgroup_to_release = block_rsv->qgroup_rsv_size; } //qgroup_to_release isn't used if (block_rsv->qgroup_rsv_reserved >= block_rsv->qgroup_rsv_size) { qgroup_to_release = block_rsv->qgroup_rsv_reserved - block_rsv->qgroup_rsv_size; block_rsv->qgroup_rsv_reserved = block_rsv->qgroup_rsv_size; } else { qgroup_to_release = 0; }//qgroup_to_release is overwritten ... } Thanks, Kaixu -- kaixuxia