From patchwork Wed Jul 1 20:09:41 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11637211 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B95C013BD for ; Wed, 1 Jul 2020 20:24:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A06DF2085B for ; Wed, 1 Jul 2020 20:24:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="OKVqcm4q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727887AbgGAUYP (ORCPT ); Wed, 1 Jul 2020 16:24:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49314 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727838AbgGAUXU (ORCPT ); Wed, 1 Jul 2020 16:23:20 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CCDE3C08C5DC; Wed, 1 Jul 2020 13:23:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=RHUcUsvFM01nbSipjJ9wbpJn0M6zNebEekts07Aqyyk=; b=OKVqcm4qQdk5NaMWLBudEqHkLA J96QDK0UycV8OAw8rULwatZGK7JiINTEwwtOXCb1eBW8aXgFGaOCgcYFrdV+D6yz0Bzq4DDMwhNU8 ZZbgOLvvFO6dBUO4lQo5QUriGVHPiUltjpW4Avf2drtbEllrLG81fEg0M+yxzlEg/KFlp70v+NrCJ hzTJnvOIFxRqF093N1ec/Ewu2LbqlSABhspSLqJu0Xv1cEauyjLlsy6VBGwRQXj71IevHoCaR/hAR Dp4o1OKhA4J8xhvw3MffeMcr9wkXQaZ8nCywUKKucl28Bakxc7I8w81CwhdruE1hrLRR/1FEJU6c8 v5z1YtnA==; Received: from [2001:4bb8:18c:3b3b:379a:a079:66b5:89c3] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jqjGD-0002Qw-5x; Wed, 01 Jul 2020 20:23:13 +0000 From: Christoph Hellwig To: Al Viro , Linus Torvalds Cc: Luis Chamberlain , Matthew Wilcox , Kees Cook , Iurii Zaikin , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH 13/23] fs: don't change the address limit for ->read_iter in __kernel_read Date: Wed, 1 Jul 2020 22:09:41 +0200 Message-Id: <20200701200951.3603160-14-hch@lst.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200701200951.3603160-1-hch@lst.de> References: <20200701200951.3603160-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org If we read to a file that implements ->read_iter there is no need to change the address limit if we send a kvec down. Signed-off-by: Christoph Hellwig --- fs/read_write.c | 40 +++++++++++++++++++++++++--------------- 1 file changed, 25 insertions(+), 15 deletions(-) diff --git a/fs/read_write.c b/fs/read_write.c index 6a2170eaee64f9..8bec4418543994 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -421,7 +421,6 @@ static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, lo ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos) { - mm_segment_t old_fs = get_fs(); ssize_t ret; if (WARN_ON_ONCE(!(file->f_mode & FMODE_READ))) @@ -431,14 +430,25 @@ ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos) if (count > MAX_RW_COUNT) count = MAX_RW_COUNT; - set_fs(KERNEL_DS); - if (file->f_op->read) + if (file->f_op->read) { + mm_segment_t old_fs = get_fs(); + + set_fs(KERNEL_DS); ret = file->f_op->read(file, (void __user *)buf, count, pos); - else if (file->f_op->read_iter) - ret = new_sync_read(file, (void __user *)buf, count, pos); - else + set_fs(old_fs); + } else if (file->f_op->read_iter) { + struct kvec iov = { .iov_base = buf, .iov_len = count }; + struct kiocb kiocb; + struct iov_iter iter; + + init_sync_kiocb(&kiocb, file); + kiocb.ki_pos = *pos; + iov_iter_kvec(&iter, READ, &iov, 1, count); + ret = file->f_op->read_iter(&kiocb, &iter); + *pos = kiocb.ki_pos; + } else { ret = -EINVAL; - set_fs(old_fs); + } if (ret > 0) { fsnotify_access(file); add_rchar(current, ret); @@ -520,7 +530,14 @@ ssize_t __kernel_write(struct file *file, const void *buf, size_t count, if (count > MAX_RW_COUNT) count = MAX_RW_COUNT; - if (file->f_op->write_iter) { + if (file->f_op->write) { + mm_segment_t old_fs = get_fs(); + + set_fs(KERNEL_DS); + ret = file->f_op->write(file, (__force const char __user *)buf, + count, pos); + set_fs(old_fs); + } else if (file->f_op->write_iter) { struct kvec iov = { .iov_base = (void *)buf, .iov_len = count }; struct kiocb kiocb; struct iov_iter iter; @@ -531,13 +548,6 @@ ssize_t __kernel_write(struct file *file, const void *buf, size_t count, ret = file->f_op->write_iter(&kiocb, &iter); if (ret > 0) *pos = kiocb.ki_pos; - } else if (file->f_op->write) { - mm_segment_t old_fs = get_fs(); - - set_fs(KERNEL_DS); - ret = file->f_op->write(file, (__force const char __user *)buf, - count, pos); - set_fs(old_fs); } else { ret = -EINVAL; }