[Qemu-devel] [PATCH v2 1/5] qemu-img: Convert by cluster size if target is compressed

[Fam Zheng <famz@redhat.com>]

If target block driver forces compression (bdi.is_compressed == true),
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>
---
 include/block/block.h | 1 +
 qemu-img.c            | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/include/block/block.h b/include/block/block.h
index 963a61f..826b5da 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -34,6 +34,7 @@ typedef struct BlockDriverInfo {
      * opened with BDRV_O_UNMAP flag for this to work.
      */
     bool can_write_zeroes_with_unmap;
+    bool is_compressed;
 } BlockDriverInfo;
 
 typedef struct BlockFragInfo {
diff --git a/qemu-img.c b/qemu-img.c
index c989850..859b927 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1425,11 +1425,14 @@ static int img_convert(int argc, char **argv)
     cluster_sectors = 0;
     ret = bdrv_get_info(out_bs, &bdi);
     if (ret < 0) {
+        /* We don't care whether bdrv_get_info() fails or not unless we are to
+         * compress */
         if (compress) {
             error_report("could not get block driver info");
             goto out;
         }
     } else {
+        compress = compress || bdi.is_compressed;
         cluster_sectors = bdi.cluster_size / BDRV_SECTOR_SIZE;
     }
 
-- 
1.8.5.4