On Thu, Jan 10, 2019 at 02:07:14PM -0800, Suren Baghdasaryan wrote:

From: Johannes Weiner <hannes@cmpxchg.org>

Kernfs has a standardized poll/notification mechanism for waking all
pollers on all fds when a filesystem node changes. To allow polling
for custom events, add a .poll callback that can override the default.

This is in preparation for pollable cgroup pressure files which have
per-fd trigger configurations.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>