block: Consistently call bdrv_activate() outside coroutine

Migration code can call bdrv_activate() in coroutine context, whereas
other callers call it outside of coroutines. As it calls other code that
is not supposed to run in coroutines, standardise on running outside of
coroutines.

This adds a no_co_wrapper to switch to the main loop before calling
bdrv_activate().

Cc: qemu-stable@nongnu.org
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20230504115750.54437-3-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit da4afaf)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(mjt: remove [no_]coroutine_fn markers which don't exist in 7.2)

block/block-backend.c

@@ -1959,7 +1959,15 @@ void blk_activate(BlockBackend *blk, Error **errp)
         return;
     }
 
-    bdrv_activate(bs, errp);
+    /*
+     * Migration code can call this function in coroutine context, so leave
+     * coroutine context if necessary.
+     */
+    if (qemu_in_coroutine()) {
+        bdrv_co_activate(bs, errp);
+    } else {
+        bdrv_activate(bs, errp);
+    }
 }
 
 bool blk_is_inserted(BlockBackend *blk)

include/block/block-global-state.h

@@ -138,6 +138,9 @@ BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs,
                                         const char *node_name, Error **errp);
 
 int bdrv_activate(BlockDriverState *bs, Error **errp);
+
+int bdrv_co_activate(BlockDriverState *bs, Error **errp);
+
 void bdrv_activate_all(Error **errp);
 int bdrv_inactivate_all(void);