qemu-img: do not zero-pad the compressed write buffer
bdrv_write_compressed() does not allow requests that span the end of the
device. Therefore it is useless to zero-pad the last cluster and
thereby exceed the end of the device.
Let image formats handle zero-padding the final compressed cluster, if
necessary.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/qemu-img.c b/qemu-img.c
index 31627b0..cd096a1 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1425,12 +1425,8 @@
}
assert (remainder == 0);
- if (n < cluster_sectors) {
- memset(buf + n * 512, 0, cluster_size - n * 512);
- }
- if (!buffer_is_zero(buf, cluster_size)) {
- ret = bdrv_write_compressed(out_bs, sector_num, buf,
- cluster_sectors);
+ if (!buffer_is_zero(buf, n * BDRV_SECTOR_SIZE)) {
+ ret = bdrv_write_compressed(out_bs, sector_num, buf, n);
if (ret != 0) {
error_report("error while compressing sector %" PRId64
": %s", sector_num, strerror(-ret));