From nobody Tue Dec 16 13:00:30 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 1532964290208457.7340397624454; Mon, 30 Jul 2018 08:24:50 -0700 (PDT) Received: from localhost ([::1]:53225 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fkA2T-0005f9-0m for importer@patchew.org; Mon, 30 Jul 2018 11:24:49 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44159) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fk9oW-0003Og-Br for qemu-devel@nongnu.org; Mon, 30 Jul 2018 11:10:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fk9oV-0008Nr-Fg for qemu-devel@nongnu.org; Mon, 30 Jul 2018 11:10:24 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:38578 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fk9oN-0008IH-1Q; Mon, 30 Jul 2018 11:10:15 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9FEE57C6CA; Mon, 30 Jul 2018 15:10:14 +0000 (UTC) Received: from localhost.localdomain.com (ovpn-117-86.ams2.redhat.com [10.36.117.86]) by smtp.corp.redhat.com (Postfix) with ESMTP id C9207112D189; Mon, 30 Jul 2018 15:10:13 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Date: Mon, 30 Jul 2018 17:09:54 +0200 Message-Id: <20180730150958.14607-10-kwolf@redhat.com> In-Reply-To: <20180730150958.14607-1-kwolf@redhat.com> References: <20180730150958.14607-1-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Mon, 30 Jul 2018 15:10:14 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Mon, 30 Jul 2018 15:10:14 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'kwolf@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PULL 09/13] block: Fix documentation for BDRV_REQ_MAY_UNMAP 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, peter.maydell@linaro.org, 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" BDRV_REQ_MAY_UNMAP in a write_zeroes request does not only allow the driver to unmap the blocks, but it actively requests that the blocks be unmapped afterwards if at all possible. Signed-off-by: Kevin Wolf --- include/block/block.h | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/include/block/block.h b/include/block/block.h index f85e3a6ed3..4e0871aaf9 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -43,11 +43,12 @@ typedef struct BlockFragInfo { typedef enum { BDRV_REQ_COPY_ON_READ =3D 0x1, BDRV_REQ_ZERO_WRITE =3D 0x2, - /* The BDRV_REQ_MAY_UNMAP flag is used to indicate that the block driv= er - * is allowed to optimize a write zeroes request by unmapping (discard= ing) - * blocks if it is guaranteed that the result will read back as - * zeroes. The flag is only passed to the driver if the block device is - * opened with BDRV_O_UNMAP. + + /* + * The BDRV_REQ_MAY_UNMAP flag is used in write_zeroes requests to ind= icate + * that the block driver should unmap (discard) blocks if it is guaran= teed + * that the result will read back as zeroes. The flag is only passed t= o the + * driver if the block device is opened with BDRV_O_UNMAP. */ BDRV_REQ_MAY_UNMAP =3D 0x4, =20 --=20 2.13.6