From nobody Sun Oct 5 21:14:36 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1542248134046932.2978243611312; Wed, 14 Nov 2018 18:15:34 -0800 (PST) Received: from localhost ([::1]:35664 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gN7Br-00032A-0t for importer@patchew.org; Wed, 14 Nov 2018 21:15:31 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53763) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gN70u-0002QC-OG for qemu-devel@nongnu.org; Wed, 14 Nov 2018 21:04:13 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gN70r-0005ky-Kl for qemu-devel@nongnu.org; Wed, 14 Nov 2018 21:04:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:32910) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gN70m-0005ft-Pg; Wed, 14 Nov 2018 21:04:04 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 820CE80F90; Thu, 15 Nov 2018 02:04:01 +0000 (UTC) Received: from red.redhat.com (ovpn-123-32.rdu2.redhat.com [10.10.123.32]) by smtp.corp.redhat.com (Postfix) with ESMTP id B5F0E60BF6; Thu, 15 Nov 2018 02:04:00 +0000 (UTC) From: Eric Blake To: qemu-devel@nongnu.org Date: Wed, 14 Nov 2018 20:03:31 -0600 Message-Id: <20181115020334.1189829-11-eblake@redhat.com> In-Reply-To: <20181115020334.1189829-1-eblake@redhat.com> References: <20181115020334.1189829-1-eblake@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Thu, 15 Nov 2018 02:04:01 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v2 10/13] file-posix: Audit for read/write 64-bit cleanness X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Any use of aio is inherently limited by size_t aio_nbytes in struct aiocb. read() is similarly limited to size_t bytes, although in practice, the ssize_t return means any read attempt on a 32-bit platform for more than 2G will likely return a short read (if that much memory was even available to begin with). And while preadv() can technically read more than size_t bytes by use of more than one iov, the fact that you can only pass a finite number of iov each of which is limited to size_t bytes is a limiting factor. While we already attempt other methods at populating a more reasonable max_transfer limit in the cases where the kernel makes that information available, it is important that we at least let the block layer know about our hard limitation of size_t bytes (mainly applicable to 32-bit compilation). At the same time, on 64-bit platforms, that means we are now advertising that we don't have any other unintended size-botching problems, if the block layer were to start handing us requests larger than 2G. Signed-off-by: Eric Blake --- block/file-posix.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/block/file-posix.c b/block/file-posix.c index 48ad3bb372a..4b43ff8cb5c 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -1073,6 +1073,9 @@ static void raw_refresh_limits(BlockDriverState *bs, = Error **errp) raw_probe_alignment(bs, s->fd, errp); bs->bl.min_mem_alignment =3D s->buf_align; bs->bl.opt_mem_alignment =3D MAX(s->buf_align, getpagesize()); + if (!bs->bl.max_transfer) { + bs->bl.max_transfer =3D SIZE_MAX; + } } static int check_for_dasd(int fd) --=20 2.17.2