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[Qemu-devel] [PATCH 1/3] vmdk: Fix COW
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH 1/3] vmdk: Fix COW |
Date: |
Fri, 16 Apr 2010 21:59:56 +0200 |
When trying to do COW, VMDK wrote the data back to the backing file. This
problem was revealed by the patch that made backing files read-only. This patch
does not only fix the problem, but also simplifies the VMDK code a bit.
This fixes the backing file qemu-iotests cases for VMDK.
Signed-off-by: Kevin Wolf <address@hidden>
---
block/vmdk.c | 35 +++++++++++------------------------
1 files changed, 11 insertions(+), 24 deletions(-)
diff --git a/block/vmdk.c b/block/vmdk.c
index 5ef4375..ae34121 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -87,14 +87,6 @@ typedef struct VmdkMetaData {
int valid;
} VmdkMetaData;
-typedef struct ActiveBDRVState{
- BlockDriverState *hd; // active image handler
- uint64_t cluster_offset; // current write offset
-}ActiveBDRVState;
-
-static ActiveBDRVState activeBDRV;
-
-
static int vmdk_probe(const uint8_t *buf, int buf_size, const char *filename)
{
uint32_t magic;
@@ -492,30 +484,28 @@ static uint64_t get_cluster_offset(BlockDriverState *bs,
VmdkMetaData *m_data,
static int get_whole_cluster(BlockDriverState *bs, uint64_t cluster_offset,
uint64_t offset, int allocate)
{
- uint64_t parent_cluster_offset;
BDRVVmdkState *s = bs->opaque;
uint8_t whole_grain[s->cluster_sectors*512]; // 128 sectors * 512
bytes each = grain size 64KB
// 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) {
- BDRVVmdkState *ps = bs->backing_hd->opaque;
+ int ret;
if (!vmdk_is_cid_valid(bs))
return -1;
- parent_cluster_offset = get_cluster_offset(bs->backing_hd, NULL,
- offset, allocate);
-
- if (parent_cluster_offset) {
- BDRVVmdkState *act_s = activeBDRV.hd->opaque;
-
- if (bdrv_pread(ps->hd, parent_cluster_offset, whole_grain,
ps->cluster_sectors*512) != ps->cluster_sectors*512)
- return -1;
+ ret = bdrv_read(bs->backing_hd, offset >> 9, whole_grain,
+ s->cluster_sectors);
+ if (ret < 0) {
+ return -1;
+ }
- //Write grain only into the active image
- if (bdrv_pwrite(act_s->hd, activeBDRV.cluster_offset << 9,
whole_grain, sizeof(whole_grain)) != sizeof(whole_grain))
- return -1;
+ //Write grain only into the active image
+ ret = bdrv_write(s->hd, cluster_offset, whole_grain,
+ s->cluster_sectors);
+ if (ret < 0) {
+ return -1;
}
}
return 0;
@@ -601,9 +591,6 @@ static uint64_t get_cluster_offset(BlockDriverState *bs,
VmdkMetaData *m_data,
cluster_offset >>= 9;
tmp = cpu_to_le32(cluster_offset);
l2_table[l2_index] = tmp;
- // Save the active image state
- activeBDRV.cluster_offset = cluster_offset;
- activeBDRV.hd = bs;
}
/* First of all we write grain itself, to avoid race condition
* that may to corrupt the image.
--
1.6.6.1