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 0B376C4320A for ; Fri, 23 Jul 2021 20:59:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EB17D60F23 for ; Fri, 23 Jul 2021 20:59:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231428AbhGWUSo (ORCPT ); Fri, 23 Jul 2021 16:18:44 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:41857 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231447AbhGWUSl (ORCPT ); Fri, 23 Jul 2021 16:18:41 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1627073953; 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=pFei+s+fWvJWvz6iB+WUaD924M10iRi+eomBo7E3jgU=; b=ZMYLassu/4GqQuk+yyq6t3kJP0OEIlt3y0bzG5WzUsw9c92QKfSt8acsyY+h6Ykw4BapuU R663MOT2aiuIZI9gUtpgTmQHhp9NSL4qJP2oTJQrUicR0LB7f9TAMK2kSmzBk7i+ahj8gG CR1nEQxKsMa7FEp4aL0tQZOpWiyoXBs= 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-225-X45yxMnRO86KqkwtcPyfmg-1; Fri, 23 Jul 2021 16:59:10 -0400 X-MC-Unique: X45yxMnRO86KqkwtcPyfmg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 04261801A92; Fri, 23 Jul 2021 20:59:09 +0000 (UTC) Received: from max.com (unknown [10.40.194.164]) by smtp.corp.redhat.com (Postfix) with ESMTP id E53CB10074FD; Fri, 23 Jul 2021 20:59:02 +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 v3 6/7] iov_iter: Introduce noio flag to disable page faults Date: Fri, 23 Jul 2021 22:58:39 +0200 Message-Id: <20210723205840.299280-7-agruenba@redhat.com> In-Reply-To: <20210723205840.299280-1-agruenba@redhat.com> References: <20210723205840.299280-1-agruenba@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 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 152b3605e86c..8de6354ade14 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 7221665f7ac4..a20426cedf60 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -509,6 +509,7 @@ 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, @@ -1519,13 +1520,17 @@ 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; @@ -1641,15 +1646,20 @@ 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