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, 1 insertions, 1 deletions

diff --git a/qemu-img.c b/qemu-img.c
index bd5a2ae22e..a095d42d30 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -2968,7 +2968,7 @@ static int img_amend(int argc, char **argv)
         goto out;
     }
 
-    ret = bdrv_amend_options(bs, opts);
+    ret = bdrv_amend_options(bs, opts, NULL);
     if (ret < 0) {
         error_report("Error while amending options: %s", strerror(-ret));
         goto out;