block: Convert bdrv_pwrite_compressed() to BdrvChild

Signed-off-by: NPavel Butsykin <pbutsykin@virtuozzo.com>
Signed-off-by: NDenis V. Lunev <den@openvz.org>
Reviewed-by: NEric Blake <eblake@redhat.com>
CC: Jeff Cody <jcody@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Eric Blake <eblake@redhat.com>
CC: John Snow <jsnow@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/block-backend.c

@@ -1493,7 +1493,7 @@ int blk_pwrite_compressed(BlockBackend *blk, int64_t offset, const void *buf,
         return ret;
     }
 
-    return bdrv_pwrite_compressed(blk_bs(blk), offset, buf, count);
+    return bdrv_pwrite_compressed(blk->root, offset, buf, count);
 }
 
 int blk_truncate(BlockBackend *blk, int64_t offset)

block/io.c

@@ -1868,9 +1868,10 @@ int bdrv_is_allocated_above(BlockDriverState *top,
     return 0;
 }
 
-int bdrv_pwrite_compressed(BlockDriverState *bs, int64_t offset,
+int bdrv_pwrite_compressed(BdrvChild *child, int64_t offset,
                            const void *buf, int bytes)
 {
+    BlockDriverState *bs = child->bs;
     BlockDriver *drv = bs->drv;
     int ret;
 

include/block/block.h

@@ -399,7 +399,7 @@ const char *bdrv_get_node_name(const BlockDriverState *bs);
 const char *bdrv_get_device_name(const BlockDriverState *bs);
 const char *bdrv_get_device_or_node_name(const BlockDriverState *bs);
 int bdrv_get_flags(BlockDriverState *bs);
-int bdrv_pwrite_compressed(BlockDriverState *bs, int64_t offset,
+int bdrv_pwrite_compressed(BdrvChild *child, int64_t offset,
                            const void *buf, int bytes);
 int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi);
 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs);