From patchwork Thu May 15 03:20:15 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Cody X-Patchwork-Id: 349044 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id BBB65140094 for ; Thu, 15 May 2014 13:21:35 +1000 (EST) Received: from localhost ([::1]:55441 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WkmEf-0004Qp-ER for incoming@patchwork.ozlabs.org; Wed, 14 May 2014 23:21:33 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57397) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WkmDx-0003P7-AH for qemu-devel@nongnu.org; Wed, 14 May 2014 23:20:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WkmDp-0001rI-Ou for qemu-devel@nongnu.org; Wed, 14 May 2014 23:20:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:25726) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WkmDp-0001qU-Ey for qemu-devel@nongnu.org; Wed, 14 May 2014 23:20:41 -0400 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s4F3KdMg001382 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Wed, 14 May 2014 23:20:39 -0400 Received: from localhost (ovpn-112-27.phx2.redhat.com [10.3.112.27]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id s4F3Kbk7000972 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO); Wed, 14 May 2014 23:20:39 -0400 From: Jeff Cody To: qemu-devel@nongnu.org Date: Wed, 14 May 2014 23:20:15 -0400 Message-Id: In-Reply-To: References: In-Reply-To: References: X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: kwolf@redhat.com, benoit.canet@irqsave.net, pkrempa@redhat.com, famz@redhat.com, stefanha@redhat.com Subject: [Qemu-devel] [PATCH 1/5] block: Auto-generate node_names for each BDS entry X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Currently, node_name is only filled in when done so explicitly by the user. If no node_name is specified, then the node name field is not populated. If node_names are automatically generated when not specified, that means that all block job operations can be done by reference to the unique node_name field. This eliminates ambiguity in filename pathing (relative filenames, or file descriptors, symlinks, mounts, etc..) that qemu currently needs to deal with. If a node name is specified, then it will not be automatically generated for that BDS entry. If it is automatically generated, it will be prefaced with "__qemu##", followed by 8 characters of a unique number, followed by 8 random ASCII characters in the range of 'A-Z'. Some sample generated node-name strings: __qemu##00000000IAIYNXXR __qemu##00000002METXTRBQ __qemu##00000001FMBORDWG The prefix is to aid in identifying it as a qemu-generated name, the numeric portion is to guarantee uniqueness in a given qemu session, and the random characters are to further avoid any accidental collisions with user-specified node-names. Signed-off-by: Jeff Cody Reviewed-by: Eric Blake --- block.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/block.c b/block.c index c90c71a..81945d3 100644 --- a/block.c +++ b/block.c @@ -838,12 +838,26 @@ static int bdrv_open_flags(BlockDriverState *bs, int flags) return open_flags; } +#define GEN_NODE_NAME_PREFIX "__qemu##" +#define GEN_NODE_NAME_MAX_LEN (sizeof(GEN_NODE_NAME_PREFIX) + 8 + 8) static void bdrv_assign_node_name(BlockDriverState *bs, const char *node_name, Error **errp) { + char gen_node_name[GEN_NODE_NAME_MAX_LEN]; + static uint32_t counter; /* simple counter to guarantee uniqueness */ + + /* if node_name is NULL, auto-generate a node name */ if (!node_name) { - return; + int len; + snprintf(gen_node_name, GEN_NODE_NAME_MAX_LEN, + "%s%08x", GEN_NODE_NAME_PREFIX, counter++); + len = strlen(gen_node_name); + while (len < GEN_NODE_NAME_MAX_LEN - 1) { + gen_node_name[len++] = g_random_int_range('A', 'Z'); + } + gen_node_name[GEN_NODE_NAME_MAX_LEN - 1] = '\0'; + node_name = gen_node_name; } /* empty string node name is invalid */