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 432C6C74A5B for ; Wed, 29 Mar 2023 18:41:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229747AbjC2SlU (ORCPT ); Wed, 29 Mar 2023 14:41:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44788 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229740AbjC2SlN (ORCPT ); Wed, 29 Mar 2023 14:41:13 -0400 Received: from mail-io1-xd2e.google.com (mail-io1-xd2e.google.com [IPv6:2607:f8b0:4864:20::d2e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 360C330D2 for ; Wed, 29 Mar 2023 11:41:11 -0700 (PDT) Received: by mail-io1-xd2e.google.com with SMTP id k17so7251870iob.1 for ; Wed, 29 Mar 2023 11:41:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; t=1680115270; x=1682707270; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=s4CO9nZAOAEco+zmBX+Z9tyoqzZd7VU/Gm6MZ2qt56o=; b=D/5ASckaf9bmeXQFyqcdTogslw5IeiU+xWykjuvsXK0mkhQvzu9TjlOnSrqsslmXiV YEYCJa3SS+i6eFCs5Tzs/Z3gciOEiFbUZ9OLlyijYb1jYMmwRWC092RVGt7YBwUHfdQ7 AQv2ndCagPn82WTvL6unRZmwFnHMuxAMNYxeTpARBHmI/yzTO9NgSIMKSDSCO/UW6vew TJbpVAf3i7CPneRozC0Rsir1My+hu7IfxreiYeQlk19Xq6dc7MqbWo1RlSiRF4t/LLxF U9EsyHsrVFhXIXaCykWeljjoIEisZ/hVrvAhS74g00y1FLwaOJEn5L0WKCQf+a46G/Bx 235A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680115270; x=1682707270; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=s4CO9nZAOAEco+zmBX+Z9tyoqzZd7VU/Gm6MZ2qt56o=; b=umDP8c1PRBbF9iiRcfdNVtJQ6OMgWMw50bVrpAefz3nXDBD3LJtMGQMVtbY31AjIm3 4YlfzwoI7Wc+/CYZdap/1vc3G11SVVnybd6aYsOwURtLXa1U91jf2L33Ji260jHJiCUU j/EF9BUif/vnU7NSewiChnpI0k1/zMEYKcs+MTr6fcmjAzHiVFA/qGmyFAS85dvumDO+ dFwuCobJH1vDoIHqyqDqnGNdYFCGqmcbiaj0/vFDu2lw77IoUOQElSnFeJAaxvW8OZ9X b6FH80//ErHmpoOB2/w9Xw516CHGTUY6vTjauQI5joTiDU0ZTligbXAVIbTWmSBwxd21 DyKw== X-Gm-Message-State: AO0yUKUHXErGkHZAkVbmlB2IKj0TjkuQ5OXEkB7Qsh+xDdJcbOJri4Hb QTQJhfWJR4jfkgGBPRDpaCgFOmaG0e9/fVdTShrHug== X-Google-Smtp-Source: AK7set8s6XH1rW3hkG7I+hLmnxVFSRTZwvgT9dcWQn8IU4XmhJybOycFMg7y2SAPkX/0pIZJEbZnag== X-Received: by 2002:a05:6602:72c:b0:719:6a2:99d8 with SMTP id g12-20020a056602072c00b0071906a299d8mr9141433iox.0.1680115270601; Wed, 29 Mar 2023 11:41:10 -0700 (PDT) Received: from localhost.localdomain ([96.43.243.2]) by smtp.gmail.com with ESMTPSA id m36-20020a056638272400b004063e6fb351sm10468087jav.89.2023.03.29.11.41.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Mar 2023 11:41:10 -0700 (PDT) From: Jens Axboe To: linux-fsdevel@vger.kernel.org Cc: torvalds@linux-foundation.org, brauner@kernel.org, viro@zeniv.linux.org.uk, Jens Axboe Subject: [PATCH 11/11] iov_iter: import single vector iovecs as ITER_UBUF Date: Wed, 29 Mar 2023 12:40:55 -0600 Message-Id: <20230329184055.1307648-12-axboe@kernel.dk> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230329184055.1307648-1-axboe@kernel.dk> References: <20230329184055.1307648-1-axboe@kernel.dk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Add a special case to __import_iovec(), which imports a single segment iovec as an ITER_UBUF rather than an ITER_IOVEC. ITER_UBUF is cheaper to iterate than ITER_IOVEC, and for a single segment iovec, there's no point in using a segmented iterator. Signed-off-by: Jens Axboe --- lib/iov_iter.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/lib/iov_iter.c b/lib/iov_iter.c index f411bda1171f..3e6c9bcfa612 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -1784,6 +1784,30 @@ struct iovec *iovec_from_user(const struct iovec __user *uvec, return iov; } +/* + * Single segment iovec supplied by the user, import it as ITER_UBUF. + */ +static ssize_t __import_iovec_ubuf(int type, const struct iovec __user *uvec, + struct iovec **iovp, struct iov_iter *i, + bool compat) +{ + struct iovec *iov = *iovp; + ssize_t ret; + + if (compat) + ret = copy_compat_iovec_from_user(iov, uvec, 1); + else + ret = copy_iovec_from_user(iov, uvec, 1); + if (unlikely(ret)) + return ret; + + ret = import_ubuf(type, iov->iov_base, iov->iov_len, i); + if (unlikely(ret)) + return ret; + *iovp = NULL; + return i->count; +} + ssize_t __import_iovec(int type, const struct iovec __user *uvec, unsigned nr_segs, unsigned fast_segs, struct iovec **iovp, struct iov_iter *i, bool compat) @@ -1792,6 +1816,9 @@ ssize_t __import_iovec(int type, const struct iovec __user *uvec, unsigned long seg; struct iovec *iov; + if (nr_segs == 1) + return __import_iovec_ubuf(type, uvec, iovp, i, compat); + iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat); if (IS_ERR(iov)) { *iovp = NULL; -- 2.39.2