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From 66922efc83a670178b208dec2f5123ec85fb6ba3 Mon Sep 17 00:00:00 2001
From: Fam Zheng <famcool@gmail.com>
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 <famcool@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
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) {
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