From patchwork Fri Sep 25 06:17:29 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wen Congyang X-Patchwork-Id: 522639 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 1A35A140281 for ; Fri, 25 Sep 2015 16:19:07 +1000 (AEST) Received: from localhost ([::1]:40143 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZfMLZ-0007zy-45 for incoming@patchwork.ozlabs.org; Fri, 25 Sep 2015 02:19:05 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46665) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZfMKm-0006lX-Hn for qemu-devel@nongnu.org; Fri, 25 Sep 2015 02:18:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZfMKk-00040y-5V for qemu-devel@nongnu.org; Fri, 25 Sep 2015 02:18:16 -0400 Received: from [59.151.112.132] (port=3369 helo=heian.cn.fujitsu.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZfMKj-00040K-G7; Fri, 25 Sep 2015 02:18:14 -0400 X-IronPort-AV: E=Sophos;i="5.15,520,1432569600"; d="scan'208";a="101089645" Received: from unknown (HELO edo.cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 25 Sep 2015 14:20:54 +0800 Received: from G08CNEXCHPEKD01.g08.fujitsu.local (localhost.localdomain [127.0.0.1]) by edo.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id t8P6HpAS004591; Fri, 25 Sep 2015 14:17:51 +0800 Received: from G08FNSTD140052.g08.fujitsu.local (10.167.226.52) by G08CNEXCHPEKD01.g08.fujitsu.local (10.167.33.89) with Microsoft SMTP Server (TLS) id 14.3.181.6; Fri, 25 Sep 2015 14:18:10 +0800 From: Wen Congyang To: qemu devel , Fam Zheng , Max Reitz , Paolo Bonzini , Stefan Hajnoczi Date: Fri, 25 Sep 2015 14:17:29 +0800 Message-ID: <1443161858-20533-2-git-send-email-wency@cn.fujitsu.com> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1443161858-20533-1-git-send-email-wency@cn.fujitsu.com> References: <1443161858-20533-1-git-send-email-wency@cn.fujitsu.com> MIME-Version: 1.0 X-Originating-IP: [10.167.226.52] X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 59.151.112.132 Cc: Kevin Wolf , qemu block , Jiang Yunhong , Dong Eddie , "Dr. David Alan Gilbert" , "Michael R. Hines" , Gonglei , Yang Hongyang , zhanghailiang Subject: [Qemu-devel] [PATCH v10 01/10] allow writing to the backing file 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 For block replication, we have such backing chain: secondary disk <-- hidden disk <-- active disk secondary disk is top BDS(use bacing reference), so it can be opened in read-write mode. But hidden disk is read only, and we need to write to hidden disk(backup job will write data to it). TODO: support opening backing file in read-write mode if the BDS is created by QMP command blockdev-add. Signed-off-by: Wen Congyang Signed-off-by: zhanghailiang Signed-off-by: Gonglei --- block.c | 41 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-) diff --git a/block.c b/block.c index 073d8d6..328c52f 100644 --- a/block.c +++ b/block.c @@ -738,6 +738,15 @@ static const BdrvChildRole child_backing = { .inherit_flags = bdrv_backing_flags, }; +static int bdrv_backing_rw_flags(int flags) +{ + return bdrv_backing_flags(flags) | BDRV_O_RDWR; +} + +static const BdrvChildRole child_backing_rw = { + .inherit_flags = bdrv_backing_rw_flags, +}; + static int bdrv_open_flags(BlockDriverState *bs, int flags) { int open_flags = flags | BDRV_O_CACHE_WB; @@ -1150,6 +1159,20 @@ out: bdrv_refresh_limits(bs, NULL); } +#define ALLOW_WRITE_BACKING_FILE "allow-write-backing-file" +static QemuOptsList backing_file_opts = { + .name = "backing_file", + .head = QTAILQ_HEAD_INITIALIZER(backing_file_opts.head), + .desc = { + { + .name = ALLOW_WRITE_BACKING_FILE, + .type = QEMU_OPT_BOOL, + .help = "allow writes to backing file", + }, + { /* end of list */ } + }, +}; + /* * Opens the backing file for a BlockDriverState if not yet open * @@ -1164,6 +1187,9 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) int ret = 0; BlockDriverState *backing_hd; Error *local_err = NULL; + QemuOpts *opts = NULL; + bool child_rw = false; + const BdrvChildRole *child_role = NULL; if (bs->backing_hd != NULL) { QDECREF(options); @@ -1176,6 +1202,18 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) } bs->open_flags &= ~BDRV_O_NO_BACKING; + + opts = qemu_opts_create(&backing_file_opts, NULL, 0, &error_abort); + qemu_opts_absorb_qdict(opts, options, &local_err); + if (local_err) { + ret = -EINVAL; + error_propagate(errp, local_err); + QDECREF(options); + goto free_exit; + } + child_rw = qemu_opt_get_bool(opts, ALLOW_WRITE_BACKING_FILE, false); + child_role = child_rw ? &child_backing_rw : &child_backing; + if (qdict_haskey(options, "file.filename")) { backing_filename[0] = '\0'; } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) { @@ -1208,7 +1246,7 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) assert(bs->backing_hd == NULL); ret = bdrv_open_inherit(&backing_hd, *backing_filename ? backing_filename : NULL, - NULL, options, 0, bs, &child_backing, &local_err); + NULL, options, 0, bs, child_role, &local_err); if (ret < 0) { bdrv_unref(backing_hd); backing_hd = NULL; @@ -1222,6 +1260,7 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) bdrv_set_backing_hd(bs, backing_hd); free_exit: + qemu_opts_del(opts); g_free(backing_filename); return ret; }