qemu-img: Convert by cluster size if target is compressed

If target block driver forces compression, qemu-img convert needs to
write by cluster size as well as "-c" option.

Particularly, this applies for converting to VMDK streamOptimized
format.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/qemu-img.c b/qemu-img.c
index 317bc6c1cd..04ce02aeb4 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1502,6 +1502,7 @@ static int img_convert(int argc, char **argv)
             goto out;
         }
     } else {
+        compress = compress || bdi.needs_compressed_writes;
         cluster_sectors = bdi.cluster_size / BDRV_SECTOR_SIZE;
     }