[v2,13/33] block: Add child_of_bds

Commit Message

Max Reitz Feb. 4, 2020, 5:08 p.m. UTC

Any current user of child_file, child_format, and child_backing can and
should use this generic BdrvChildClass instead, as it can handle all of
these cases.  However, to be able to do so, the users must pass the
appropriate BdrvChildRole when the child is created/attached.  (The
following commits will take care of that.)

Signed-off-by: Max Reitz <[e-mail]>
---
 block.c                   | 27 +++++++++++++++++++++++++++
 include/block/block_int.h |  1 +
 2 files changed, 28 insertions(+)

Comments

Eric Blake Feb. 5, 2020, 8:33 p.m. UTC | #1

On 2/4/20 11:08 AM, Max Reitz wrote:
> Any current user of child_file, child_format, and child_backing can and
> should use this generic BdrvChildClass instead, as it can handle all of
> these cases.  However, to be able to do so, the users must pass the
> appropriate BdrvChildRole when the child is created/attached.  (The
> following commits will take care of that.)
> 
> Signed-off-by: Max Reitz <[e-mail]>
> ---
>   block.c                   | 27 +++++++++++++++++++++++++++
>   include/block/block_int.h |  1 +
>   2 files changed, 28 insertions(+)
> 
Reviewed-by: Eric Blake <[e-mail]>

Patch

diff --git a/block.c b/block.c
index 46fc08e227..1816e92674 100644
--- a/block.c
+++ b/block.c
@@ -1072,6 +1072,33 @@  static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format,
     *child_flags = flags;
 }
 
+static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base,
+                                        const char *filename, Error **errp);
+
+static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base,
+                                         const char *filename, Error **errp)
+{
+    if (c->role & BDRV_CHILD_COW) {
+        return bdrv_backing_update_filename(c, base, filename, errp);
+    }
+    return 0;
+}
+
+const BdrvChildClass child_of_bds = {
+    .parent_is_bds   = true,
+    .get_parent_desc = bdrv_child_get_parent_desc,
+    .inherit_options = bdrv_inherited_options,
+    .drained_begin   = bdrv_child_cb_drained_begin,
+    .drained_poll    = bdrv_child_cb_drained_poll,
+    .drained_end     = bdrv_child_cb_drained_end,
+    .attach          = bdrv_child_cb_attach,
+    .detach          = bdrv_child_cb_detach,
+    .inactivate      = bdrv_child_cb_inactivate,
+    .can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx,
+    .set_aio_ctx     = bdrv_child_cb_set_aio_ctx,
+    .update_filename = bdrv_child_cb_update_filename,
+};
+
 /*
  * Returns the options and flags that bs->file should get if a protocol driver
  * is expected, based on the given options and flags for the parent BDS
diff --git a/include/block/block_int.h b/include/block/block_int.h
index f4c673620f..91883c1e80 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -740,6 +740,7 @@  struct BdrvChildClass {
     void (*set_aio_ctx)(BdrvChild *child, AioContext *ctx, GSList **ignore);
 };
 
+extern const BdrvChildClass child_of_bds;
 extern const BdrvChildClass child_file;
 extern const BdrvChildClass child_format;
 extern const BdrvChildClass child_backing;