[PATCH v2 3/4] block: Add blk_make_empty()

[Max Reitz <mreitz@redhat.com>]

Two callers of BlockDriver.bdrv_make_empty() remain that should not call
this method directly.  Both do not have access to a BdrvChild, but they
can use a BlockBackend, so we add this function that lets them use it.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 include/sysemu/block-backend.h |  2 ++
 block/block-backend.c          | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index 0917663d89..8203d7f6f9 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -266,4 +266,6 @@ int coroutine_fn blk_co_copy_range(BlockBackend *blk_in, int64_t off_in,
 
 const BdrvChild *blk_root(BlockBackend *blk);
 
+int blk_make_empty(BlockBackend *blk, Error **errp);
+
 #endif
diff --git a/block/block-backend.c b/block/block-backend.c
index f4944861fa..47bd56244d 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -2402,3 +2402,13 @@ const BdrvChild *blk_root(BlockBackend *blk)
 {
     return blk->root;
 }
+
+int blk_make_empty(BlockBackend *blk, Error **errp)
+{
+    if (!blk_is_available(blk)) {
+        error_setg(errp, "No medium inserted");
+        return -ENOMEDIUM;
+    }
+
+    return bdrv_make_empty(blk->root, errp);
+}
-- 
2.25.4