From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:47553) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Qb2pO-0000O4-C9 for qemu-devel@nongnu.org; Sun, 26 Jun 2011 23:49:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Qb2pM-0007Vs-P5 for qemu-devel@nongnu.org; Sun, 26 Jun 2011 23:49:37 -0400 Received: from mail-iw0-f173.google.com ([209.85.214.173]:59042) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Qb2pM-0007Vj-9R for qemu-devel@nongnu.org; Sun, 26 Jun 2011 23:49:36 -0400 Received: by iwn3 with SMTP id 3so4689050iwn.4 for ; Sun, 26 Jun 2011 20:49:35 -0700 (PDT) From: Fam Zheng Date: Mon, 27 Jun 2011 11:48:28 +0800 Message-Id: <1309146518-8998-3-git-send-email-famcool@gmail.com> In-Reply-To: <1309146518-8998-1-git-send-email-famcool@gmail.com> References: <1309146518-8998-1-git-send-email-famcool@gmail.com> Subject: [Qemu-devel] [PATCH v3 02/12] VMDK: bugfix, align offset to cluster in get_whole_cluster List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, Fam Zheng , hch@lst.de, stefanha@gmail.com In get_whole_cluster, the offset is not aligned to cluster when reading from backing_hd. When the first write to child is not at the cluster boundary, wrong address data from parent is copied to child. Signed-off-by: Fam Zheng --- block/vmdk.c | 8 +++++--- 1 files changed, 5 insertions(+), 3 deletions(-) diff --git a/block/vmdk.c b/block/vmdk.c index c7246f0..0540ec5 100644 --- a/block/vmdk.c +++ b/block/vmdk.c @@ -485,21 +485,23 @@ static int get_whole_cluster(BlockDriverState *bs, /* 128 sectors * 512 bytes each = grain size 64KB */ uint8_t whole_grain[extent->cluster_sectors * 512]; - // we will be here if it's first write on non-exist grain(cluster). - // try to read from parent image, if exist + /* we will be here if it's first write on non-exist grain(cluster). + * try to read from parent image, if exist */ if (bs->backing_hd) { int ret; if (!vmdk_is_cid_valid(bs)) return -1; + /* floor offset to cluster */ + offset -= offset % (extent->cluster_sectors * 512); ret = bdrv_read(bs->backing_hd, offset >> 9, whole_grain, extent->cluster_sectors); if (ret < 0) { return -1; } - //Write grain only into the active image + /* Write grain only into the active image */ ret = bdrv_write(extent->file, cluster_offset, whole_grain, extent->cluster_sectors); if (ret < 0) {