From patchwork Tue Jul 7 08:43:10 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wen Congyang X-Patchwork-Id: 492105 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 B4E661402BA for ; Tue, 7 Jul 2015 18:49:40 +1000 (AEST) Received: from localhost ([::1]:55837 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZCOZO-0005pT-UU for incoming@patchwork.ozlabs.org; Tue, 07 Jul 2015 04:49:38 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42257) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZCOSD-0001Nz-Ow for qemu-devel@nongnu.org; Tue, 07 Jul 2015 04:42:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZCOSA-0003RJ-DS for qemu-devel@nongnu.org; Tue, 07 Jul 2015 04:42:13 -0400 Received: from [59.151.112.132] (port=62005 helo=heian.cn.fujitsu.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZCOS6-0001Wo-Bk; Tue, 07 Jul 2015 04:42:10 -0400 X-IronPort-AV: E=Sophos;i="5.13,665,1427731200"; d="scan'208";a="98163946" Received: from unknown (HELO edo.cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 07 Jul 2015 16:43:41 +0800 Received: from G08CNEXCHPEKD02.g08.fujitsu.local (localhost.localdomain [127.0.0.1]) by edo.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id t678c5VX010470; Tue, 7 Jul 2015 16:38:05 +0800 Received: from G08FNSTD140052.g08.fujitsu.local (10.167.226.52) by G08CNEXCHPEKD02.g08.fujitsu.local (10.167.33.89) with Microsoft SMTP Server (TLS) id 14.3.181.6; Tue, 7 Jul 2015 16:39:46 +0800 From: Wen Congyang To: qemu devel , Fam Zheng , Max Reitz , Paolo Bonzini , Stefan Hajnoczi Date: Tue, 7 Jul 2015 16:43:10 +0800 Message-ID: <1436258596-1253-13-git-send-email-wency@cn.fujitsu.com> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1436258596-1253-1-git-send-email-wency@cn.fujitsu.com> References: <1436258596-1253-1-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 COLO-BLOCK v8 12/18] block: Allow references for backing files 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 Usage: -drive file=xxx,id=Y, \ -drive file=xxxx,id=X,backing.backing_reference=Y It will create such backing chain: {virtio-blk dev 'Y'} {virtio-blk dev 'X'} | | | | v v [base] <- [mid] <- ( Y ) <----------------- ( X ) Signed-off-by: Wen Congyang Signed-off-by: zhanghailiang Signed-off-by: Gonglei --- block.c | 39 +++++++++++++++++++++++++++++++++++---- include/block/block.h | 1 + 2 files changed, 36 insertions(+), 4 deletions(-) diff --git a/block.c b/block.c index 879ca75..f7192a3 100644 --- a/block.c +++ b/block.c @@ -1143,6 +1143,7 @@ out: } #define ALLOW_WRITE_BACKING_FILE "allow-write-backing-file" +#define BACKING_REFERENCE "backing_reference" static QemuOptsList backing_file_opts = { .name = "backing_file", .head = QTAILQ_HEAD_INITIALIZER(backing_file_opts.head), @@ -1152,6 +1153,11 @@ static QemuOptsList backing_file_opts = { .type = QEMU_OPT_BOOL, .help = "allow write to backing file", }, + { + .name = BACKING_REFERENCE, + .type = QEMU_OPT_STRING, + .help = "reference to the exsiting BDS", + }, { /* end of list */ } }, }; @@ -1168,11 +1174,12 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) { char *backing_filename = g_malloc0(PATH_MAX); int ret = 0; - BlockDriverState *backing_hd; + BlockDriverState *backing_hd = NULL; Error *local_err = NULL; QemuOpts *opts = NULL; bool child_rw = false; const BdrvChildRole *child_role = NULL; + const char *reference = NULL; if (bs->backing_hd != NULL) { QDECREF(options); @@ -1195,9 +1202,10 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) goto free_exit; } child_rw = qemu_opt_get_bool(opts, ALLOW_WRITE_BACKING_FILE, false); + reference = qemu_opt_get(opts, BACKING_REFERENCE); child_role = child_rw ? &child_backing_rw : &child_backing; - if (qdict_haskey(options, "file.filename")) { + if (qdict_haskey(options, "file.filename") || reference) { backing_filename[0] = '\0'; } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) { QDECREF(options); @@ -1220,7 +1228,9 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) goto free_exit; } - backing_hd = bdrv_new(); + if (!reference) { + backing_hd = bdrv_new(); + } if (bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) { qdict_put(options, "driver", qstring_from_str(bs->backing_format)); @@ -1229,7 +1239,7 @@ 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_role, + reference, options, 0, bs, child_role, NULL, &local_err); if (ret < 0) { bdrv_unref(backing_hd); @@ -1240,12 +1250,30 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp) error_free(local_err); goto free_exit; } + if (reference) { + if (bdrv_op_is_blocked(backing_hd, BLOCK_OP_TYPE_BACKING_REFERENCE, + errp)) { + ret = -EBUSY; + goto free_reference_exit; + } + if (backing_hd->blk && blk_disable_attach_dev(backing_hd->blk)) { + error_setg(errp, "backing_hd %s is used by the other device model", + reference); + ret = -EBUSY; + goto free_reference_exit; + } + } bdrv_set_backing_hd(bs, backing_hd); free_exit: qemu_opts_del(opts); g_free(backing_filename); return ret; + +free_reference_exit: + bdrv_unref(backing_hd); + bs->open_flags |= BDRV_O_NO_BACKING; + goto free_exit; } /* @@ -1899,6 +1927,9 @@ void bdrv_close(BlockDriverState *bs) if (bs->backing_hd) { BlockDriverState *backing_hd = bs->backing_hd; bdrv_set_backing_hd(bs, NULL); + if (backing_hd->blk) { + blk_enable_attach_dev(backing_hd->blk); + } bdrv_unref(backing_hd); } bs->drv->bdrv_close(bs); diff --git a/include/block/block.h b/include/block/block.h index cbe79bc..db52306 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -168,6 +168,7 @@ typedef enum BlockOpType { BLOCK_OP_TYPE_RESIZE, BLOCK_OP_TYPE_STREAM, BLOCK_OP_TYPE_REPLACE, + BLOCK_OP_TYPE_BACKING_REFERENCE, BLOCK_OP_TYPE_MAX, } BlockOpType;