From nobody Sat Nov 1 22:49:27 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=virtuozzo.com Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1527071552616544.1954162867692; Wed, 23 May 2018 03:32:32 -0700 (PDT) Received: from localhost ([::1]:60456 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fLR4B-0004Xh-5X for importer@patchew.org; Wed, 23 May 2018 06:32:23 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35956) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fLQxP-00083Y-NC for qemu-devel@nongnu.org; Wed, 23 May 2018 06:25:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fLQxK-0003tb-3N for qemu-devel@nongnu.org; Wed, 23 May 2018 06:25:23 -0400 Received: from relay.sw.ru ([185.231.240.75]:43776) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fLQwz-0003gg-Hr; Wed, 23 May 2018 06:24:57 -0400 Received: from msk-vpn.virtuozzo.com ([195.214.232.6] helo=kvm.sw.ru) by relay.sw.ru with esmtp (Exim 4.90_1) (envelope-from ) id 1fLQwt-0006Rs-49; Wed, 23 May 2018 13:24:51 +0300 From: Vladimir Sementsov-Ogievskiy To: qemu-block@nongnu.org, qemu-devel@nongnu.org Date: Wed, 23 May 2018 13:24:19 +0300 Message-Id: <20180523102419.28665-6-vsementsov@virtuozzo.com> X-Mailer: git-send-email 2.11.1 In-Reply-To: <20180523102419.28665-1-vsementsov@virtuozzo.com> References: <20180523102419.28665-1-vsementsov@virtuozzo.com> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 185.231.240.75 Subject: [Qemu-devel] [PATCH v3 5/5] docs/interop: add nbd.txt 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, vsementsov@virtuozzo.com, armbru@redhat.com, mreitz@redhat.com, den@openvz.org, pbonzini@redhat.com 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" Describe new metadata namespace: "qemu". Signed-off-by: Vladimir Sementsov-Ogievskiy --- docs/interop/nbd.txt | 37 +++++++++++++++++++++++++++++++++++++ MAINTAINERS | 1 + 2 files changed, 38 insertions(+) create mode 100644 docs/interop/nbd.txt diff --git a/docs/interop/nbd.txt b/docs/interop/nbd.txt new file mode 100644 index 0000000000..7366269fc0 --- /dev/null +++ b/docs/interop/nbd.txt @@ -0,0 +1,37 @@ +Qemu supports NBD protocol, and has internal NBD client (look at +block/nbd.c), internal NBD server (look at blockdev-nbd.c) as well as +external NBD server tool - qemu-nbd.c. The common code is placed in +nbd/*. + +NBD protocol is specified here: +https://github.com/NetworkBlockDevice/nbd/blob/master/doc/proto.md + +This following paragraphs describe some specific properties of NBD +protocol realization in Qemu. + + +=3D Metadata namespaces =3D + +Qemu supports "base:allocation" metadata context as defined in the NBD +protocol specification and defines own metadata namespace: "qemu". + + +=3D=3D "qemu" namespace =3D=3D + +For now, the only type of metadata context in the namespace is dirty +bitmap. All available metadata contexts have the following form: + + qemu:dirty-bitmap: + +Each dirty-bitmap metadata context defines the only one flag for +extents in reply for NBD_CMD_BLOCK_STATUS: + + bit 0: NBD_STATE_DIRTY, means that the extent is "dirty" + +For NBD_OPT_LIST_META_CONTEXT the following queries are supported +additionally to "qemu:dirty-bitmap:": + +* "qemu:" : returns list of all available metadata contexts in the + namespace. +* "qemu:dirty-bitmap:" : returns list of all available dirty-bitmap + metadata contexts. diff --git a/MAINTAINERS b/MAINTAINERS index e187b1f18f..887b479440 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -1923,6 +1923,7 @@ F: nbd/ F: include/block/nbd* F: qemu-nbd.* F: blockdev-nbd.c +F: docs/interop/nbd.txt T: git git://repo.or.cz/qemu/ericb.git nbd =20 NFS --=20 2.11.1