migration: Report when bdrv_inactivate_all fails
If the bdrv_inactivate_all fails near the end of the migration,
the migration will fail and often the only diagnostics in the log
are an I/O error which you can't distinguish from an error on
the socket connection.
Add an error so we know when it's actually a block problem.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <
20170822170212.27347-1-dgilbert@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>