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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 DAA47C4743D for ; Sun, 6 Jun 2021 19:11:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BA67B6120D for ; Sun, 6 Jun 2021 19:11:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230416AbhFFTNq (ORCPT ); Sun, 6 Jun 2021 15:13:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54088 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230155AbhFFTMp (ORCPT ); Sun, 6 Jun 2021 15:12:45 -0400 Received: from zeniv-ca.linux.org.uk (zeniv-ca.linux.org.uk [IPv6:2607:5300:60:148a::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 05890C061789; Sun, 6 Jun 2021 12:10:55 -0700 (PDT) Received: from viro by zeniv-ca.linux.org.uk with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1lpyAf-0056ak-VR; Sun, 06 Jun 2021 19:10:54 +0000 From: Al Viro To: Linus Torvalds Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, David Sterba , Miklos Szeredi , Anton Altaparmakov , David Howells , Matthew Wilcox , Pavel Begunkov Subject: [RFC PATCH 19/37] [xarray] iov_iter_npages(): just use DIV_ROUND_UP() Date: Sun, 6 Jun 2021 19:10:33 +0000 Message-Id: <20210606191051.1216821-19-viro@zeniv.linux.org.uk> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210606191051.1216821-1-viro@zeniv.linux.org.uk> References: <20210606191051.1216821-1-viro@zeniv.linux.org.uk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Compiler is capable of recognizing division by power of 2 and turning it into shifts. Signed-off-by: Al Viro --- lib/iov_iter.c | 16 ++-------------- 1 file changed, 2 insertions(+), 14 deletions(-) diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 04c81481d309..6a968d2ff081 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -1938,20 +1938,8 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages) return min(npages, maxpages); } if (iov_iter_is_xarray(i)) { - size_t size = i->count; - unsigned offset; - int npages; - - offset = (i->xarray_start + i->iov_offset) & ~PAGE_MASK; - - npages = 1; - if (size > PAGE_SIZE - offset) { - size -= PAGE_SIZE - offset; - npages += size >> PAGE_SHIFT; - size &= ~PAGE_MASK; - if (size) - npages++; - } + unsigned offset = (i->xarray_start + i->iov_offset) % PAGE_SIZE; + int npages = DIV_ROUND_UP(offset + i->count, PAGE_SIZE); return min(npages, maxpages); } return 0; -- 2.11.0