From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47528) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dmUCC-0000v0-IA for qemu-devel@nongnu.org; Mon, 28 Aug 2017 20:15:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dmUCA-0005Bf-ET for qemu-devel@nongnu.org; Mon, 28 Aug 2017 20:15:56 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:48696) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dmUCA-0005Af-3t for qemu-devel@nongnu.org; Mon, 28 Aug 2017 20:15:54 -0400 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v7T0E85d005466 for ; Mon, 28 Aug 2017 20:15:53 -0400 Received: from e12.ny.us.ibm.com (e12.ny.us.ibm.com [129.33.205.202]) by mx0a-001b2d01.pphosted.com with ESMTP id 2cmvjejk4c-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 28 Aug 2017 20:15:52 -0400 Received: from localhost by e12.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 28 Aug 2017 20:15:51 -0400 From: Michael Roth Date: Mon, 28 Aug 2017 19:13:54 -0500 In-Reply-To: <1503965694-10794-1-git-send-email-mdroth@linux.vnet.ibm.com> References: <1503965694-10794-1-git-send-email-mdroth@linux.vnet.ibm.com> Message-Id: <1503965694-10794-20-git-send-email-mdroth@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH 19/79] block: Reuse bs as backing hd for drive-backup sync=none List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Fam Zheng , Kevin Wolf From: Fam Zheng Opening the backing image for the second time is bad, especially here when it is also in use as the active image as the source. The drive-backup job itself doesn't read from target->backing for COW, instead it gets data from the write notifier, so it's not a big problem. However, exporting the target to NBD etc. won't work, because of the likely stale metadata cache. Use BDRV_O_NO_BACKING in this case and manually set up the backing BdrvChild. Cc: qemu-stable@nongnu.org Signed-off-by: Fam Zheng Signed-off-by: Kevin Wolf (cherry picked from commit fc0932fdcfc3e5cafa3641e361b681c07f639812) Signed-off-by: Michael Roth --- blockdev.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/blockdev.c b/blockdev.c index e2f9c1e..841200e 100644 --- a/blockdev.c +++ b/blockdev.c @@ -3170,6 +3170,7 @@ static BlockJob *do_drive_backup(DriveBackup *backup, BlockJobTxn *txn, Error *local_err = NULL; int flags; int64_t size; + bool set_backing_hd = false; if (!backup->has_speed) { backup->speed = 0; @@ -3220,6 +3221,8 @@ static BlockJob *do_drive_backup(DriveBackup *backup, BlockJobTxn *txn, } if (backup->sync == MIRROR_SYNC_MODE_NONE) { source = bs; + flags |= BDRV_O_NO_BACKING; + set_backing_hd = true; } size = bdrv_getlength(bs); @@ -3246,7 +3249,9 @@ static BlockJob *do_drive_backup(DriveBackup *backup, BlockJobTxn *txn, } if (backup->format) { - options = qdict_new(); + if (!options) { + options = qdict_new(); + } qdict_put_str(options, "driver", backup->format); } @@ -3257,6 +3262,14 @@ static BlockJob *do_drive_backup(DriveBackup *backup, BlockJobTxn *txn, bdrv_set_aio_context(target_bs, aio_context); + if (set_backing_hd) { + bdrv_set_backing_hd(target_bs, source, &local_err); + if (local_err) { + bdrv_unref(target_bs); + goto out; + } + } + if (backup->has_bitmap) { bmap = bdrv_find_dirty_bitmap(bs, backup->bitmap); if (!bmap) { -- 2.7.4