From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48041) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VZ4IV-0002Ab-Ez for qemu-devel@nongnu.org; Wed, 23 Oct 2013 15:40:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VZ4IP-00018W-Av for qemu-devel@nongnu.org; Wed, 23 Oct 2013 15:40:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:10196) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VZ4IP-00018N-3e for qemu-devel@nongnu.org; Wed, 23 Oct 2013 15:40:45 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r9NJeiwG013083 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 23 Oct 2013 15:40:44 -0400 From: Max Reitz Date: Wed, 23 Oct 2013 21:40:41 +0200 Message-Id: <1382557241-23117-1-git-send-email-mreitz@redhat.com> Subject: [Qemu-devel] [PATCH] qcow2: Flush image after creation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Stefan Hajnoczi , Max Reitz Opening the qcow2 image with BDRV_O_NO_FLUSH prevents any flushes during the image creation. This means that the image has not yet been flushed to disk when qemu-img create exits. This flush is delayed until the next operation on the image involving opening it without BDRV_O_NO_FLUSH and closing (or directly flushing) it. For large images and/or images with a small cluster size and preallocated metadata, this flush may take a significant amount of time and may occur unexpectedly. Reopening the image without BDRV_O_NO_FLUSH right before the end of qcow2_create2() results in preponing the potentially costly flush into the image creation, which is expected to take some time (whereas successive image operations may be not). Signed-off-by: Max Reitz --- block/qcow2.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/block/qcow2.c b/block/qcow2.c index c1abaff..8b98c3a 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1584,7 +1584,15 @@ static int qcow2_create2(const char *filename, int64_t total_size, } } - ret = 0; + bdrv_close(bs); + + /* Reopen the image without BDRV_O_NO_FLUSH to flush it before returning */ + ret = bdrv_open(bs, filename, NULL, + BDRV_O_RDWR | BDRV_O_CACHE_WB, drv, &local_err); + if (error_is_set(&local_err)) { + error_propagate(errp, local_err); + } + out: bdrv_unref(bs); return ret; -- 1.8.3.1