Notify sysfs about changes of a nvme controller so user-space can watch the
file via poll() or select() in order to react to a state change.
Userspace has no business polling for the state.
Please consider this patch. At least upstream multipath-tools is using the sysfs state now:
[1] https://git.opensvc.com/gitweb.cgi?p=multipath-tools/.git;a=commitdiff;h=29c3b0446c4d919859f9e87b291563d483aab594
[2] https://git.opensvc.com/gitweb.cgi?p=multipath-tools/.git;a=commitdiff;h=d2561442cc0b444e8a728bac2c1466468816ee9d