When issuing a compressed write request the number of bytes must be a multiple of the cluster size.
With the current code such requests are allowed and we hit an assertion: $ qemu-img create -f qcow2 img.qcow2 1M $ qemu-io -c 'write -c 0 32k' img.qcow2 qemu-io: block/qcow2.c:4257: qcow2_co_pwritev_compressed_task: Assertion `bytes == s->cluster_size || (bytes < s->cluster_size && (offset + bytes == bs->total_sectors << BDRV_SECTOR_BITS))' failed. Aborted This patch fixes a regression introduced in 0d483dce38 Signed-off-by: Alberto Garcia <be...@igalia.com> --- block/qcow2.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/qcow2.c b/block/qcow2.c index 2bb536b014..923ad428f0 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -4345,7 +4345,7 @@ qcow2_co_pwritev_compressed_part(BlockDriverState *bs, return bdrv_co_truncate(bs->file, len, false, PREALLOC_MODE_OFF, NULL); } - if (offset_into_cluster(s, offset)) { + if (offset_into_cluster(s, offset | bytes)) { return -EINVAL; } -- 2.20.1