Re: [PATCH 07/17] proc/fd: In tid_fd_mode use fcheck_task

Christian Brauner
2020-08-18T10:37:00Z

On Mon, Aug 17, 2020 at 05:04:15PM -0500, Eric W. Biederman wrote:
> When discussing[1] exec and posix file locks it was realized that none
> of the callers of get_files_struct fundamentally needed to call
> get_files_struct, and that by switching them to helper functions
> instead it will both simplify their code and remove unnecessary
> increments of files_struct.count. Those unnecessary increments can
> result in exec unnecessarily unsharing files_struct which breaking
> posix locks, and it can result in fget_light having to fallback to
> fget reducing system performance.
>
> Using fcheck_task instead of get_files_struct clarifies tid_fd_mode by
> removing a step.
>
> [1] https://lkml.kernel.org/r/20180915160423.GA31461@redhat.com
> Suggested-by: Oleg Nesterov <oleg@redhat.com>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---

Acked-by: Christian Brauner <christian.brauner@ubuntu.com>