Even though block cloning is much faster than regular copying,
it is not instantaneous - the file might be large and the recordsize
small. It would be nice to be able to interrupt it with a signal
(e.g., SIGINFO on FreeBSD to see the progress).
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Pawel Jakub Dawidek <pawel@dawidek.net>
Closes#16208