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 93000C76196 for ; Tue, 28 Mar 2023 21:58:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230064AbjC1V6h (ORCPT ); Tue, 28 Mar 2023 17:58:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55588 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230039AbjC1V62 (ORCPT ); Tue, 28 Mar 2023 17:58:28 -0400 Received: from mail-pl1-x62e.google.com (mail-pl1-x62e.google.com [IPv6:2607:f8b0:4864:20::62e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3C6A22133 for ; Tue, 28 Mar 2023 14:58:26 -0700 (PDT) Received: by mail-pl1-x62e.google.com with SMTP id o11so13077131ple.1 for ; Tue, 28 Mar 2023 14:58:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; t=1680040705; x=1682632705; 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=VRuLnY8LfItYmha1a1+5ihq4yOs2ex342r7sq+hJ1lo=; b=MTVixB4gdxpihVL1VGQWs5h5wNMMUS/gfef/ejNAZ5guuyhHrUtFCx29PeOdr2y+HR hwkUgBoFc94Vw7bz2OErGxr9W3FJjDfKMARKDcAhlgr+PsNIAEnK7Ts5ay5Ab6B6Bp8c x5/N+E8clWHS1g5x+ekIdCgJUdO/r4VYc35V5SNwlN+4Z1JG/jAKNsZF8IbPm//o4fcj +AQec/iDjPlyDpq6FDHmnlx1+tAOOjrUtL5UCyVzRRAvNU1OfpZIjufmx2BJfVF5gtjy hK3RgITIWW7QNsO6rdBVmuL/E+cyYcpLVVkAKS711vog4GHDc4HoKv/QKcVmjj3UpENR cDMw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680040705; x=1682632705; 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=VRuLnY8LfItYmha1a1+5ihq4yOs2ex342r7sq+hJ1lo=; b=RBXwm4Lpyw0j0qYAqbud3gtKdjCK+N+nglsqPpyGVQnnNrEkMWwx2PwCafzI4+NHWt MIQdmfPW+ewjq1hrb4DZoiQKd/icCZ8qeDCtgC8kUf05fvekuDxyHzgO4/m2rNDaMcp3 Fu+HhwU4x0DL9kcUSVt0Hh20+93tb2u6v84etAj8XsTJFhmgNQ/F4VIDnZO3WfpqU85Z WY56qFc5sB3wi/A6gBDVN6vF+RsQGvfNrzLjFvMtqEQBh0bV1erp6+/yUI8251yOfkgW MvUSZmSvUxLkJvZSZ3De/VCGr3s2wxRWS71SyQOLrTwTWh6pGR2OE6JEOF9+TrbhKyzt PoxQ== X-Gm-Message-State: AAQBX9cBFhnQZu5Bwgye+A8rwZrBXXNJwsuUSUJa7SSDVch/M87+LETI KBhekOz2l3BCr7djydT6gyvl0L/MnvAkznJzeQIRGQ== X-Google-Smtp-Source: AKy350bTARPh+OLDk+YoaIZ1t9lgnmu5eizU5k8KG6Jqs5dOkgP1MDvtEeat17jk6NfcYDPjTEB/aA== X-Received: by 2002:a17:903:788:b0:1a1:bf37:7c2e with SMTP id kn8-20020a170903078800b001a1bf377c2emr14314208plb.4.1680040705379; Tue, 28 Mar 2023 14:58:25 -0700 (PDT) Received: from localhost.localdomain ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id t20-20020a1709028c9400b001a04b92ddffsm21560171plo.140.2023.03.28.14.58.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Mar 2023 14:58:24 -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 9/9] iov_iter: import single vector iovecs as ITER_UBUF Date: Tue, 28 Mar 2023 15:58:11 -0600 Message-Id: <20230328215811.903557-10-axboe@kernel.dk> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230328215811.903557-1-axboe@kernel.dk> References: <20230328215811.903557-1-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 fc82cc42ffe6..63cf9997bd50 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -1780,6 +1780,30 @@ 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) @@ -1788,6 +1812,9 @@ 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