qcow2: Respect bdrv_truncate() error

bdrv_truncate() may fail and qcow2_write_compressed() should return the
error code in that case.

Cc: [email protected]
Signed-off-by: Max Reitz <[email protected]>
Reviewed-by: Kevin Wolf <[email protected]>
Signed-off-by: Kevin Wolf <[email protected]>
(cherry picked from commit 6a69b96)

Conflicts:
	block/qcow2.c

*removed context dependency on 75d3d21

Signed-off-by: Michael Roth <[email protected]>

Author: XanClic

block/qcow2.c

@@ -1960,8 +1960,7 @@ static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num,
            sector based I/Os */
         cluster_offset = bdrv_getlength(bs->file);
         cluster_offset = (cluster_offset + 511) & ~511;
-        bdrv_truncate(bs->file, cluster_offset);
-        return 0;
+        return bdrv_truncate(bs->file, cluster_offset);
     }
 
     if (nb_sectors != s->cluster_sectors) {