diff options
Diffstat (limited to 'block/qcow2.c')
| -rw-r--r-- | block/qcow2.c | 43 |
1 files changed, 34 insertions, 9 deletions
diff --git a/block/qcow2.c b/block/qcow2.c index d33fb3ecdd..970006fc1d 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -3104,18 +3104,43 @@ static int qcow2_truncate(BlockDriverState *bs, int64_t offset, } old_length = bs->total_sectors * 512; + new_l1_size = size_to_l1(s, offset); - /* shrinking is currently not supported */ if (offset < old_length) { - error_setg(errp, "qcow2 doesn't support shrinking images yet"); - return -ENOTSUP; - } + if (prealloc != PREALLOC_MODE_OFF) { + error_setg(errp, + "Preallocation can't be used for shrinking an image"); + return -EINVAL; + } - new_l1_size = size_to_l1(s, offset); - ret = qcow2_grow_l1_table(bs, new_l1_size, true); - if (ret < 0) { - error_setg_errno(errp, -ret, "Failed to grow the L1 table"); - return ret; + ret = qcow2_cluster_discard(bs, ROUND_UP(offset, s->cluster_size), + old_length - ROUND_UP(offset, + s->cluster_size), + QCOW2_DISCARD_ALWAYS, true); + if (ret < 0) { + error_setg_errno(errp, -ret, "Failed to discard cropped clusters"); + return ret; + } + + ret = qcow2_shrink_l1_table(bs, new_l1_size); + if (ret < 0) { + error_setg_errno(errp, -ret, + "Failed to reduce the number of L2 tables"); + return ret; + } + + ret = qcow2_shrink_reftable(bs); + if (ret < 0) { + error_setg_errno(errp, -ret, + "Failed to discard unused refblocks"); + return ret; + } + } else { + ret = qcow2_grow_l1_table(bs, new_l1_size, true); + if (ret < 0) { + error_setg_errno(errp, -ret, "Failed to grow the L1 table"); + return ret; + } } switch (prealloc) { |