[v4,14/34] block: Add child_of_bds

Commit Message

Max Reitz May 13, 2020, 11:05 a.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]>
---
 include/block/block_int.h |  1 +
 block.c                   | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+)

Comments

Eric Blake May 13, 2020, 8:29 p.m. UTC | #1

On 5/13/20 6:05 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]>
> ---
>   include/block/block_int.h |  1 +
>   block.c                   | 24 ++++++++++++++++++++++++
>   2 files changed, 25 insertions(+)
> 

Reviewed-by: Eric Blake <[e-mail]>

Patch

diff --git a/include/block/block_int.h b/include/block/block_int.h
index 6245d8a18d..54df821d61 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;
diff --git a/block.c b/block.c
index f63417c06d..be9bfa9d46 100644
--- a/block.c
+++ b/block.c
@@ -1429,6 +1429,30 @@  static void bdrv_child_cb_detach(BdrvChild *child)
     bdrv_unapply_subtree_drain(child, bs);
 }
 
+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,
+};
+
 static int bdrv_open_flags(BlockDriverState *bs, int flags)
 {
     int open_flags = flags;