block/copy-before-write: cbw_init(): use file child after attaching

In the next commit we'll get rid of source argument of cbw_init().
Prepare to it now, to make next commit simpler: move the code block
that uses source below attaching the child and use bs->file->bs instead
of source variable.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210824083856.17408-17-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index d7f1833efa0979281f9753d25c89c4e2d6baa6dd..4858dcf8ff53d4a5e3fd7ee254b342ff5bc5a6a3 100644 (file)
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -149,13 +149,6 @@ static int cbw_init(BlockDriverState *bs, BlockDriverState *source,
 {
     BDRVCopyBeforeWriteState *s = bs->opaque;
 
-    bs->total_sectors = source->total_sectors;
-    bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
-            (BDRV_REQ_FUA & source->supported_write_flags);
-    bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
-            ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) &
-             source->supported_zero_flags);
-
     bdrv_ref(target);
     s->target = bdrv_attach_child(bs, target, "target", &child_of_bds,
                                   BDRV_CHILD_DATA, errp);
@@ -173,6 +166,13 @@ static int cbw_init(BlockDriverState *bs, BlockDriverState *source,
         return -EINVAL;
     }
 
+    bs->total_sectors = bs->file->bs->total_sectors;
+    bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
+            (BDRV_REQ_FUA & bs->file->bs->supported_write_flags);
+    bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
+            ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) &
+             bs->file->bs->supported_zero_flags);
+
     s->bcs = block_copy_state_new(bs->file, s->target, false, compress, errp);
     if (!s->bcs) {
         error_prepend(errp, "Cannot create block-copy-state: ");