diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/vmdk.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/block/vmdk.c b/block/vmdk.c index fcd6b38d64..ab8eec1f27 100644 --- a/block/vmdk.c +++ b/block/vmdk.c @@ -1340,7 +1340,9 @@ static void vmdk_refresh_limits(BlockDriverState *bs, Error **errp) * get_whole_cluster * * Copy backing file's cluster that covers @sector_num, otherwise write zero, - * to the cluster at @cluster_sector_num. + * to the cluster at @cluster_sector_num. If @zeroed is true, we're overwriting + * a zeroed cluster in the current layer and must not copy data from the + * backing file. * * If @skip_start_sector < @skip_end_sector, the relative range * [@skip_start_sector, @skip_end_sector) is not copied or written, and leave @@ -1351,18 +1353,21 @@ static int get_whole_cluster(BlockDriverState *bs, uint64_t cluster_offset, uint64_t offset, uint64_t skip_start_bytes, - uint64_t skip_end_bytes) + uint64_t skip_end_bytes, + bool zeroed) { int ret = VMDK_OK; int64_t cluster_bytes; uint8_t *whole_grain; + bool copy_from_backing; /* For COW, align request sector_num to cluster start */ cluster_bytes = extent->cluster_sectors << BDRV_SECTOR_BITS; offset = QEMU_ALIGN_DOWN(offset, cluster_bytes); whole_grain = qemu_blockalign(bs, cluster_bytes); + copy_from_backing = bs->backing && !zeroed; - if (!bs->backing) { + if (!copy_from_backing) { memset(whole_grain, 0, skip_start_bytes); memset(whole_grain + skip_end_bytes, 0, cluster_bytes - skip_end_bytes); } @@ -1377,7 +1382,7 @@ static int get_whole_cluster(BlockDriverState *bs, /* Read backing data before skip range */ if (skip_start_bytes > 0) { - if (bs->backing) { + if (copy_from_backing) { /* qcow2 emits this on bs->file instead of bs->backing */ BLKDBG_EVENT(extent->file, BLKDBG_COW_READ); ret = bdrv_pread(bs->backing, offset, whole_grain, @@ -1397,7 +1402,7 @@ static int get_whole_cluster(BlockDriverState *bs, } /* Read backing data after skip range */ if (skip_end_bytes < cluster_bytes) { - if (bs->backing) { + if (copy_from_backing) { /* qcow2 emits this on bs->file instead of bs->backing */ BLKDBG_EVENT(extent->file, BLKDBG_COW_READ); ret = bdrv_pread(bs->backing, offset + skip_end_bytes, @@ -1631,7 +1636,8 @@ static int get_cluster_offset(BlockDriverState *bs, * or inappropriate VM shutdown. */ ret = get_whole_cluster(bs, extent, cluster_sector * BDRV_SECTOR_SIZE, - offset, skip_start_bytes, skip_end_bytes); + offset, skip_start_bytes, skip_end_bytes, + zeroed); if (ret) { return ret; } |