diff options
| -rw-r--r-- | block/qcow2-cluster.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 4b5fc8c..a677ba9 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -1797,8 +1797,15 @@ int qcow2_cluster_zeroize(BlockDriverState *bs, uint64_t offset, assert(QEMU_IS_ALIGNED(end_offset, s->cluster_size) || end_offset >= bs->total_sectors << BDRV_SECTOR_BITS); - /* The zero flag is only supported by version 3 and newer */ + /* + * The zero flag is only supported by version 3 and newer. However, if we + * have no backing file, we can resort to discard in version 2. + */ if (s->qcow_version < 3) { + if (!bs->backing) { + return qcow2_cluster_discard(bs, offset, bytes, + QCOW2_DISCARD_REQUEST, false); + } return -ENOTSUP; } |