block: Add status callback to bdrv_amend_options()

Depending on the changed options and the image format,
bdrv_amend_options() may take a significant amount of time. In these
cases, a way to be informed about the operation's status is desirable.

Since the operation is rather complex and may fundamentally change the
image, implementing it as AIO or a coroutine does not seem feasible. On
the other hand, implementing it as a block job would be significantly
more difficult than a simple callback and would not add benefits other
than progress report to the amending operation, because it should not
actually be run as a block job at all.

A callback may not be very pretty, but it's very easy to implement and
perfectly fits its purpose here.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Benoît Canet <benoit.canet@nodalink.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 1414404776-4919-2-git-send-email-mreitz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/block/block_int.h b/include/block/block_int.h
index a293e92852..a1c17b9578 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -232,7 +232,8 @@ struct BlockDriver {
     int (*bdrv_check)(BlockDriverState* bs, BdrvCheckResult *result,
         BdrvCheckMode fix);
 
-    int (*bdrv_amend_options)(BlockDriverState *bs, QemuOpts *opts);
+    int (*bdrv_amend_options)(BlockDriverState *bs, QemuOpts *opts,
+                              BlockDriverAmendStatusCB *status_cb);
 
     void (*bdrv_debug_event)(BlockDriverState *bs, BlkDebugEvent event);