From 66922efc83a670178b208dec2f5123ec85fb6ba3 Mon Sep 17 00:00:00 2001 From: Fam Zheng Date: Tue, 12 Jul 2011 19:56:29 +0800 Subject: [PATCH 03/12] VMDK: bugfix, align offset to cluster in get_whole_cluster 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 Reviewed-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- block/vmdk.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) --- a/block/vmdk.c +++ b/block/vmdk.c @@ -514,21 +514,23 @@ static int get_whole_cluster(BlockDriver /* 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) {