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=-17.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 ED54CC4338F for ; Sat, 24 Jul 2021 19:35:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D5C4A60E98 for ; Sat, 24 Jul 2021 19:35:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230166AbhGXSzD (ORCPT ); Sat, 24 Jul 2021 14:55:03 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:29458 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229895AbhGXSyy (ORCPT ); Sat, 24 Jul 2021 14:54:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1627155325; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=68SOusRsRxqdSvo7E5qry5oQaFdTx1qIpjpB5XBw6qk=; b=L/wTDAkp7oMkwfC8YMZCM6e0619o5I4MJGWULvVp3YECTuPfMnfmJ4yt6SAbpNybEavhly 1UuAdtdtPUbBaU0QMNdnZgKBlWeR3CMOks7EjSeR/ECfJenPifp78+ZTfoOg9IXL0+u1p8 xA1wrSze/EbJ7mVBmNb/srXvR2fxpSs= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-210-ZYnvvgqKNo2CLIpgzKn1Zw-1; Sat, 24 Jul 2021 15:35:24 -0400 X-MC-Unique: ZYnvvgqKNo2CLIpgzKn1Zw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A1601801AEB; Sat, 24 Jul 2021 19:35:22 +0000 (UTC) Received: from max.com (unknown [10.40.194.164]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3DF7069320; Sat, 24 Jul 2021 19:35:20 +0000 (UTC) From: Andreas Gruenbacher To: Linus Torvalds , Alexander Viro , Christoph Hellwig , "Darrick J. Wong" Cc: Jan Kara , Matthew Wilcox , cluster-devel@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com, Andreas Gruenbacher Subject: [PATCH v4 7/8] iov_iter: Introduce noio flag to disable page faults Date: Sat, 24 Jul 2021 21:34:48 +0200 Message-Id: <20210724193449.361667-8-agruenba@redhat.com> In-Reply-To: <20210724193449.361667-1-agruenba@redhat.com> References: <20210724193449.361667-1-agruenba@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Introduce a new noio flag to indicate to get_user_pages to use the FOLL_FAST_ONLY flag. This will cause get_user_pages to fail when it would otherwise fault in a page. Currently, the noio flag is only checked in iov_iter_get_pages and iov_iter_get_pages_alloc. This is enough for iomaop_dio_rw, but it may make sense to check for this flag in other contexts as well. Signed-off-by: Andreas Gruenbacher --- include/linux/uio.h | 1 + lib/iov_iter.c | 20 +++++++++++++++----- 2 files changed, 16 insertions(+), 5 deletions(-) diff --git a/include/linux/uio.h b/include/linux/uio.h index 8e469b8b862f..83cc33465295 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -29,6 +29,7 @@ enum iter_type { struct iov_iter { u8 iter_type; + bool noio; bool data_source; size_t iov_offset; size_t count; diff --git a/lib/iov_iter.c b/lib/iov_iter.c index ccf1ee8d4edf..f0fa1b89fe9b 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -507,6 +507,7 @@ void iov_iter_init(struct iov_iter *i, unsigned int direction, WARN_ON(direction & ~(READ | WRITE)); *i = (struct iov_iter) { .iter_type = ITER_IOVEC, + .noio = false, .data_source = direction, .iov = iov, .nr_segs = nr_segs, @@ -1517,13 +1518,17 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, return 0; 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->noio) + gup_flags |= FOLL_FAST_ONLY; + addr = first_iovec_segment(i, &len, start, maxsize, maxpages); n = DIV_ROUND_UP(len, PAGE_SIZE); - res = get_user_pages_fast(addr, n, - iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0, - pages); + res = get_user_pages_fast(addr, n, gup_flags, pages); if (unlikely(res <= 0)) return res; return (res == n ? len : res * PAGE_SIZE) - *start; @@ -1639,15 +1644,20 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, return 0; 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->noio) + gup_flags |= FOLL_FAST_ONLY; + addr = first_iovec_segment(i, &len, start, maxsize, ~0U); n = DIV_ROUND_UP(len, PAGE_SIZE); p = get_pages_array(n); if (!p) return -ENOMEM; - res = get_user_pages_fast(addr, n, - iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0, p); + res = get_user_pages_fast(addr, n, gup_flags, p); if (unlikely(res <= 0)) { kvfree(p); *pages = ZERO_SIZE_PTR; -- 2.26.3