One more step closer to .bdrv_open(): use options instead of plain
arguments. Move to bdrv_open_child() calls, native for drive open
handlers.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/copy-before-write.c | 40 +++++++++++++++++++++++++--------------
 1 file changed, 26 insertions(+), 14 deletions(-)

diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index 4858dcf8ff..e889af7b80 100644
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -144,25 +144,21 @@ static void cbw_child_perm(BlockDriverState *bs, BdrvChild *c,
     }
 }
 
-static int cbw_init(BlockDriverState *bs, BlockDriverState *source,
-                    BlockDriverState *target, bool compress, Error **errp)
+static int cbw_init(BlockDriverState *bs, QDict *options, Error **errp)
 {
     BDRVCopyBeforeWriteState *s = bs->opaque;
+    bool compress;
 
-    bdrv_ref(target);
-    s->target = bdrv_attach_child(bs, target, "target", &child_of_bds,
-                                  BDRV_CHILD_DATA, errp);
-    if (!s->target) {
-        error_prepend(errp, "Cannot attach target child: ");
+    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
+                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
+                               false, errp);
+    if (!bs->file) {
         return -EINVAL;
     }
 
-    bdrv_ref(source);
-    bs->file = bdrv_attach_child(bs, source, "file", &child_of_bds,
-                                 BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                                 errp);
-    if (!bs->file) {
-        error_prepend(errp, "Cannot attach file child: ");
+    s->target = bdrv_open_child(NULL, options, "target", bs, &child_of_bds,
+                                BDRV_CHILD_DATA, false, errp);
+    if (!s->target) {
         return -EINVAL;
     }
 
@@ -173,6 +169,15 @@ static int cbw_init(BlockDriverState *bs, BlockDriverState *source,
             ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) &
              bs->file->bs->supported_zero_flags);
 
+    /*
+     * The option x-deprecated-compress is only for internal use, to support
+     * compress option of backup job. New users should instead use compress
+     * filter, if they want output to be compressed.
+     * Moreover compress option of backup should probably be deprecated too.
+     * So, x-deprecated-compress is not visible through QMP.
+     */
+    compress = qdict_get_try_bool(options, "x-deprecated-compress", false);
+    qdict_del(options, "x-deprecated-compress");
     s->bcs = block_copy_state_new(bs->file, s->target, false, compress, errp);
     if (!s->bcs) {
         error_prepend(errp, "Cannot create block-copy-state: ");
@@ -210,6 +215,7 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
     int ret;
     BDRVCopyBeforeWriteState *state;
     BlockDriverState *top;
+    QDict *opts;
 
     assert(source->total_sectors == target->total_sectors);
 
@@ -221,7 +227,13 @@ BlockDriverState *bdrv_cbw_append(BlockDriverState *source,
     }
     state = top->opaque;
 
-    ret = cbw_init(top, source, target, compress, errp);
+    opts = qdict_new();
+    qdict_put_str(opts, "file", bdrv_get_node_name(source));
+    qdict_put_str(opts, "target", bdrv_get_node_name(target));
+    qdict_put_bool(opts, "x-deprecated-compress", compress);
+
+    ret = cbw_init(top, opts, errp);
+    qobject_unref(opts);
     if (ret < 0) {
         goto fail;
     }
-- 
2.29.2

On 20.05.21 16:21, Vladimir Sementsov-Ogievskiy wrote:
> One more step closer to .bdrv_open(): use options instead of plain
> arguments. Move to bdrv_open_child() calls, native for drive open
> handlers.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>   block/copy-before-write.c | 40 +++++++++++++++++++++++++--------------
>   1 file changed, 26 insertions(+), 14 deletions(-)
>

Reviewed-by: Max Reitz <mreitz@redhat.com>