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 22B5EC433EF for ; Sun, 27 Feb 2022 21:57:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231982AbiB0V6Z (ORCPT ); Sun, 27 Feb 2022 16:58:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54806 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231540AbiB0V6X (ORCPT ); Sun, 27 Feb 2022 16:58:23 -0500 Received: from mail-pf1-x430.google.com (mail-pf1-x430.google.com [IPv6:2607:f8b0:4864:20::430]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4C07625CD for ; Sun, 27 Feb 2022 13:57:46 -0800 (PST) Received: by mail-pf1-x430.google.com with SMTP id d17so9376731pfl.0 for ; Sun, 27 Feb 2022 13:57:46 -0800 (PST) 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=CLKjOtFJJy2kdF/MZbdbOY3TGf+go0L7UkS+pL1ZdSs=; b=a+VXPxxtKf7qC6FgyozL/hPV3uHnQL2GjIZxJVqNNODJTAFsvyIgElZl+LG419S28x f9wL6FgvIwC9ty1lMG3XL46p/3F2EF8LlKBGEf2WnL+OFF47WIBBnMag1SuxI4I1gc/v kvDougQh2j0dcwW9fjZoO/H78Ew3KD9Lh5BztY4xA9GMQxAfd4saaLKbrl41vBkaDStf zx90qfA9HAVf6imn8s5KejRlYjPIOxdeQ60sPQdP9+31wC5xhSvPY5OR4ViMYfb9cZOf Wbw55PTgVU2bZq4HdpGHTuMoByn1oqlw14N226EPhezkVFwI6DpKW2ZypDzmmbywqdng 3CTg== 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=CLKjOtFJJy2kdF/MZbdbOY3TGf+go0L7UkS+pL1ZdSs=; b=0Nru7cE+Tp6iin10ywkf5Lw+UMmcFBj76odokKK4A5otocgYKwA0pazR1qN7yuqz/e N+sTpjL2BCIZI8kkr9eH+0u2ohYBi8nBXhIm/V1Dk6Qg7Zy9K9qwxXnu8tUGPrpaTm3n 9ryZd3QAm/9nuAzrPH2EzV2dueKNcxSADKM2rrPLIa1Or5LhFOPrR1Ak8faS8JLtoqa/ 1wwEvTjc8w8dyDKPT5NleEQerYTDG3rylFmQLGMxoWMwUQ/JTrVuFQc6FmPTNiP4llvV jehXNRLwcCh1ZpA8TdnB+GTb2Yu46XyPRA+1EeIcks7o0mZxeFdPm9Xx4zpRIhZ2p9Cl zRCg== X-Gm-Message-State: AOAM532jczUQQmuqW3nDpa/15KlEInoE7I2+WjLqqCo+6De+2BNjKsIq /ClsM+5VHuoIjfX/ZuDd1PiLFA== X-Google-Smtp-Source: ABdhPJzIFa6TYJsLnCkUEIz+oCSZ+CKQlbxKYEKU/adzUzLJf7qo4n0bWIhWzBsHpTAnkOqmk8Ppug== X-Received: by 2002:a63:cf01:0:b0:374:2979:8407 with SMTP id j1-20020a63cf01000000b0037429798407mr14430181pgg.521.1645999065747; Sun, 27 Feb 2022 13:57:45 -0800 (PST) Received: from [192.168.4.166] (cpe-72-132-29-68.dc.res.rr.com. [72.132.29.68]) by smtp.gmail.com with ESMTPSA id f9-20020a056a00228900b004f3ba7d177csm10816506pfe.54.2022.02.27.13.57.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 27 Feb 2022 13:57:45 -0800 (PST) Message-ID: <06469550-a679-145f-b16e-2f1ffc0b07af@kernel.dk> Date: Sun, 27 Feb 2022 14:57:43 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:91.0) Gecko/20100101 Thunderbird/91.6.1 Subject: Re: [PATCH 2/6] iov_iter: new iov_iter_pin_pages*(), for FOLL_PIN pages Content-Language: en-US To: jhubbard.send.patches@gmail.com, Jan Kara , Christoph Hellwig , Dave Chinner , "Darrick J . Wong" , Theodore Ts'o , Alexander Viro , Miklos Szeredi , Andrew Morton , Chaitanya Kulkarni Cc: linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, LKML , John Hubbard References: <20220227093434.2889464-1-jhubbard@nvidia.com> <20220227093434.2889464-3-jhubbard@nvidia.com> From: Jens Axboe In-Reply-To: <20220227093434.2889464-3-jhubbard@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org > +ssize_t iov_iter_pin_pages(struct iov_iter *i, > + struct page **pages, size_t maxsize, unsigned int maxpages, > + size_t *start) > +{ > + size_t len; > + int n, res; > + > + if (maxsize > i->count) > + maxsize = i->count; > + if (!maxsize) > + return 0; > + > + WARN_ON_ONCE(!iter_is_iovec(i)); > + > + if (likely(iter_is_iovec(i))) { > + unsigned int gup_flags = 0; > + unsigned long addr; > + > + if (iov_iter_rw(i) != WRITE) > + gup_flags |= FOLL_WRITE; > + if (i->nofault) > + gup_flags |= FOLL_NOFAULT; > + > + addr = first_iovec_segment(i, &len, start, maxsize, maxpages); > + n = DIV_ROUND_UP(len, PAGE_SIZE); > + res = pin_user_pages_fast(addr, n, gup_flags, pages); > + if (unlikely(res <= 0)) > + return res; > + return (res == n ? len : res * PAGE_SIZE) - *start; Trying to be clever like that just makes the code a lot less readable. I should not have to reason about a return value. Same in the other function. -- Jens Axboe