Re: [PATCH v2 0/3] kernfs: Add inotify IN_DELETE_SELF, IN_IGNORED support for files

[Tejun Heo <tj@kernel.org>]

On Thu, Feb 12, 2026 at 01:58:11PM -0800, T.J. Mercier wrote:
> This series adds support for IN_DELETE_SELF and IN_IGNORED inotify
> events to kernfs files.
> 
> Currently, kernfs (used by cgroup and others) supports IN_MODIFY events
> but fails to notify watchers when the file is removed (e.g. during
> cgroup destruction). This forces userspace monitors to maintain resource
> intensive side-channels like pidfds, procfs polling, or redundant
> directory watches to detect when a cgroup dies and a watched file is
> removed.
> 
> By generating IN_DELETE_SELF events on destruction, we allow watchers to
> rely on a single watch descriptor for the entire lifecycle of the
> monitored file, reducing resource usage (file descriptors, CPU cycles)
> and complexity in userspace.
> 
> The series is structured as follows:
> Patch 1 refactors kernfs_elem_attr to support arbitrary event types.
> Patch 2 implements the logic to generate DELETE_SELF and IGNORED events
>         on file removal.
> Patch 3 adds selftests to verify the new behavior.

The patchset looks good to me.

Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun