From nobody Wed Dec 17 05:35:42 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.zoho.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; Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1487963102679162.63902384086316; Fri, 24 Feb 2017 11:05:02 -0800 (PST) Received: from localhost ([::1]:39457 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1chLAm-0007QK-M5 for importer@patchew.org; Fri, 24 Feb 2017 14:04:56 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49946) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1chKQr-0006Mu-DH for qemu-devel@nongnu.org; Fri, 24 Feb 2017 13:17:30 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1chKQq-0002m6-GF for qemu-devel@nongnu.org; Fri, 24 Feb 2017 13:17:29 -0500 Received: from mx1.redhat.com ([209.132.183.28]:56322) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1chKQm-0002iB-4p; Fri, 24 Feb 2017 13:17:24 -0500 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 60C6A4E4CF; Fri, 24 Feb 2017 18:17:24 +0000 (UTC) Received: from noname.redhat.com (ovpn-117-128.ams2.redhat.com [10.36.117.128]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id v1OIHDCG015460; Fri, 24 Feb 2017 13:17:23 -0500 From: Kevin Wolf To: qemu-block@nongnu.org Date: Fri, 24 Feb 2017 19:16:58 +0100 Message-Id: <1487960230-18054-8-git-send-email-kwolf@redhat.com> In-Reply-To: <1487960230-18054-1-git-send-email-kwolf@redhat.com> References: <1487960230-18054-1-git-send-email-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Fri, 24 Feb 2017 18:17:24 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 07/19] qemu-img: Improve documentation for PREALLOC_MODE_FALLOC 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-devel@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Nir Soffer Now that we are truncating the file in both PREALLOC_MODE_FULL and PREALLOC_MODE_OFF, not truncating in PREALLOC_MODE_FALLOC looks odd. Add a comment explaining why we do not truncate in this case. Signed-off-by: Nir Soffer Signed-off-by: Kevin Wolf --- block/file-posix.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/block/file-posix.c b/block/file-posix.c index d24e34b..4de1abd 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -1594,9 +1594,14 @@ static int raw_create(const char *filename, QemuOpts= *opts, Error **errp) switch (prealloc) { #ifdef CONFIG_POSIX_FALLOCATE case PREALLOC_MODE_FALLOC: - /* posix_fallocate() doesn't set errno. */ + /* + * Truncating before posix_fallocate() makes it about twice slower= on + * file systems that do not support fallocate(), trying to check i= f a + * block is allocated before allocating it, so don't do that here. + */ result =3D -posix_fallocate(fd, 0, total_size); if (result !=3D 0) { + /* posix_fallocate() doesn't set errno. */ error_setg_errno(errp, -result, "Could not preallocate data for the new file"= ); } --=20 1.8.3.1